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Sample records for active grain density

  1. Density functional calculation of activation energies for lattice and grain boundary diffusion in alumina

    NASA Astrophysics Data System (ADS)

    Lei, Yinkai; Gong, Yu; Duan, Zhiyao; Wang, Guofeng

    2013-06-01

    To acquire knowledge on the lattice and grain boundary diffusion processes in alumina, we have determined the activation energies of elementary O and Al diffusive jumps in the bulk crystal, Σ3(0001) grain boundaries, and Σ3(101¯0) grain boundaries of α-Al2O3 using the first-principles density functional theory method. Specifically, we calculated the activation energies for four elementary jumps of both O and Al lattice diffusion in alumina. It was predicted that the activation energy of O lattice diffusion varied from 3.58 to 5.03 eV, while the activation energy of Al lattice diffusion ranged from 1.80 to 3.17 eV. As compared with experimental measurements, the theoretical predictions of the activation energy for lattice diffusion were lower and thus implied that there might be other high-energy diffusive jumps in the experimental alumina samples. Moreover, our results suggested that the Al lattice diffusion was faster than the O lattice diffusion in alumina, in agreement with experiment observations. Furthermore, it was found from our calculations for α-Al2O3 that the activation energies of O and Al grain boundary diffusion in the high-energy Σ3(0001) grain boundaries were significantly lower than those of the lattice diffusion. In contrast, the activation energies of O and Al grain boundary diffusion in the low-energy Σ3(101¯0) grain boundaries could be even higher than those of the lattice diffusion.

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

    DOE PAGES

    Ott, R. T.; Geng, J.; Besser, M. F.; ...

    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. 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.

  5. Critical Technology Assessment: Fine Grain, High Density Graphite

    DTIC Science & Technology

    2010-04-01

    Control Classification Number ( ECCN ) 1C107.a on the Commerce Control List (CCL). The parameters of 1C107.a stem from controls established by the Missile...Technology Control Regime (MTCR). In this assessment, BIS specifically examined: • The application of ECCN 1C107.a and related licensing...export licensing process for fine grain, high density graphite controlled by ECCN 1C107.a, especially to China, requires more license conditions and

  6. Grain-based activated carbons for natural gas storage.

    PubMed

    Zhang, Tengyan; Walawender, Walter P; Fan, L T

    2010-03-01

    Natural gas has emerged as a potential alternative to gasoline due to the increase in global energy demand and environmental concerns. An investigation was undertaken to explore the technical feasibility of implementing the adsorbed natural gas (ANG) storage in the fuel tanks of motor vehicles with activated carbons from biomass, e.g., sorghum and wheat. The grain-based activated carbons were prepared by chemical activation; the experimental parameters were varied to identify the optimum conditions. The porosity of the resultant activated carbons was evaluated through nitrogen adsorption; and the storage capacity, through methane adsorption. A comparative study was also carried out with commercial activated carbons from charcoal. The highest storage factor attained was 89 for compacted grain-based activated carbons from grain sorghum with a bulk density of 0.65 g/cm(3), and the highest storage factor attained is 106 for compacted commercial activated carbons (Calgon) with a bulk density of 0.70 g/cm(3). The storage factor was found to increase approximately linearly with increasing bulk density and to be independent of the extent of compaction. This implies that the grain-based activated carbons are the ideal candidates for the ANG storage.

  7. Single and large grain activities at Fermilab

    SciTech Connect

    Antoine, Claire; /Fermilab

    2006-01-01

    This paper describes the ongoing activities at Fermilab for large grains and monocrystalline niobium. In addition to acquisition of local fabrication expertise, we plan to develop an R&D program dedicated to evidence the possible influence of crystal orientation on physical and chemical properties of niobium, such as mechanical properties, magnetic properties or surface contamination. Some considerations are also given about the morphology at grain boundaries and its role on the behavior of superconducting cavities.

  8. 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.

  9. Method for Assessing Grain Boundary Density in High-Strength, High-Toughness Ferritic Weld Metal

    NASA Astrophysics Data System (ADS)

    Lei, Xuanwei; Huang, Jihua; Chen, Shuhai; Zhao, Xingke

    2017-01-01

    A method for measuring peak values on the maxlength-area fraction curve and the perimeter-area fraction curve with morphological photos using Image Pro Plus 6.0 Soft for assessing grain boundary density in high-strength, high-toughness ferritic weld metals is developed. Results show the sizes of the peak values have a tough relationship with grain boundary densities in that a larger peak value stands for a larger grain boundary density. As ferrite transforms into a certain orientation relationship, this semi-empirical method provides handy references for judging the sizes of effective grain boundary densities.

  10. Principles for microwave moisture and density measurement in grain and seed.

    PubMed

    Nelson, Stuart O; Trabelsi, Samir

    2004-01-01

    The importance of cereal grain moisture content in determining time of harvest and in preserving grain quality is described. Techniques for moisture measurement, including electronic moisture meters, are also discussed briefly, and the need for better moisture sensing techniques for modern agricultural on-line moisture monitoring is described. Principles of microwave free-space measurements involving attenuation and phase-shift determination are explained, and density-independent functions of the grain permittivity are presented that permit reliable moisture sensing applicable to moving grain in which bulk density variation occurs. Three different approaches are discussed for determining moisture content and bulk density of grain from microwave measurement of the dielectric properties. A new moisture calibration function, based on complex-plane plots of dielectric constant and loss factor, each divided by bulk density, is described, which promises a universal calibration for different types of grain and seed. This important advantage should encourage commercial development for practical use.

  11. The Effect of Current Density on CNx Crystal Grain Growth in Electrochemical Deposition

    NASA Astrophysics Data System (ADS)

    Yu, Wei-Feng; Cao, Rong-Gen; Tian, Yu; Wang, Jian-Zhong; Ning, Xi-Jing

    2011-02-01

    The effect of charge current density on the growth of CNx films by electrolysis of a methanol-urea solution is investigated experimentally. It is seen that the C-C3N4 phase grains in the films are about 200-300 nm for a density of 55 mA/cm2 and dendrite growth takes place with grains as large as 7 μm formed when density is about 70 mA/cm2.

  12. Predicting stored grain insect population densities using an electronic probe trap.

    PubMed

    Flinn, P W; Opit, G P; Throne, J E

    2009-08-01

    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 OPI Insector electronic grain probes in two bins, each containing 32.6 tonnes of wheat, Triticum aestivum L., over a 2-yr period. We developed new statistical models to convert Insector catch into insects per kilogram. We compared grain sample estimates of insect density (insects per kilogram of wheat) taken near each Insector to the model-predicted insect density by using Insector counts. An existing expert system, Stored Grain Advisor Pro, was modified to automatically read the Insector database and use the appropriate model to estimate Cryptolestes ferrugineus (Stephens), Rhyzopertha dominica (F.), and Tribolium castaneum (Herbst) density from trap catch counts. Management decisions using Insector trap-catch estimates for insect density were similar to those made using grain sample estimates of insect density for most sampling dates. However, because of the similarity in size of R. dominica and T. castaneum, the software was unable to differentiate counts between these two species. In the central and southern portions of the United States, where both species frequently occur, it may be necessary to determine the proportion of each species present in the grain by manual inspection of trap catch. The combination of SGA Pro with the OPI Insector system should prove to be a useful tool for automatic monitoring of insect pests in stored grain.

  13. 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.

  14. 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.

  15. Active Free Surface Density Maps

    NASA Astrophysics Data System (ADS)

    Çelen, S.

    2016-10-01

    Percolation problems were occupied to many physical problems after their establishment in 1957 by Broadbent and Hammersley. They can be used to solve complex systems such as bone remodeling. Volume fraction method was adopted to set some algorithms in the literature. However, different rate of osteoporosis could be observed for different microstructures which have the same mass density, mechanical stimuli, hormonal stimuli and nutrition. Thus it was emphasized that the bone might have identical porosity with different specific surfaces. Active free surface density of bone refers the used total area for its effective free surface. The purpose of this manuscript is to consolidate a mathematical approach which can be called as “active free surface density maps” for different surface patterns and derive their formulations. Active free surface density ratios were calculated for different Archimedean lattice models according to Helmholtz free energy and they were compared with their site and bond percolation thresholds from the background studies to derive their potential probability for bone remodeling.

  16. 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

  17. 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.

  18. The detection of QTLs in barley associated with endosperm hardness, grain density, grain size and malting quality using rapid phenotyping tools.

    PubMed

    Walker, Cassandra K; Ford, Rebecca; Muñoz-Amatriaín, María; Panozzo, Joe F

    2013-10-01

    Using a barley mapping population, 'Vlamingh' × 'Buloke' (V × B), whole grain analyses were undertaken for physical seed traits and malting quality. Grain density and size were predicted by digital image analysis (DIA), while malt extract and protein content were predicted using near infrared (NIR) analysis. Validation of DIA and NIR algorithms confirmed that data for QTL analysis was highly correlated (R (2) > 0.82), with high RPD values (the ratio of the standard error of prediction to the standard deviation, 2.31-9.06). Endosperm hardness was measured on this mapping population using the single kernel characterisation system. Grain density and endosperm hardness were significantly inter-correlated in all three environments (r > 0.22, P < 0.001); however, other grain components were found to interact with the traits. QTL for these traits were also found on different genomic regions, for example, grain density QTLs were found on chromosomes 2H and 6H, whereas endosperm hardness QTLs were found on 1H, 5H, and 7H. In this study, the majority of the genomic regions associated with grain texture were also coincident with QTLs for grain size, yield, flowering date and/or plant development genes. This study highlights the complexity of genomic regions associated with the variation of endosperm hardness and grain density, and their relationships with grain size traits, agronomic-related traits, and plant development loci.

  19. 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.

  20. 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...

  1. Point defect absorption by grain boundaries in α -iron by atomic density function modeling

    NASA Astrophysics Data System (ADS)

    Kapikranian, O.; Zapolsky, H.; Patte, R.; Pareige, C.; Radiguet, B.; Pareige, P.

    2015-12-01

    Using the atomic density function theory (ADFT), we examine the point defect absorption at [110] symmetrical tilt grain boundaries in body-centered cubic iron. It is found that the sink strength strongly depends on misorientation angle. We also show that the ADFT is able to reproduce reasonably well the elastic properties and the point defect formation volume in α -iron.

  2. 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.

  3. 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

  4. Comparison of barley and sorghum grain processed at different densities for lactating dairy cows.

    PubMed

    Santos, F A; Huber, J T; Theurer, C B; Swingle, R S; Wu, Z; Simas, J M; Chen, K H; Chan, S C; Santos, J; DePeters, E J

    1997-09-01

    To vary ruminally degradable starch, sorghum grain was dry-rolled or steam-flaked to different densities and compared with dry-rolled barley in total mixed diets fed to 40 lactating cows (111 d of lactation) assigned to five dietary treatments. Diets contained (percentage of dry matter) 35% alfalfa hay, 4.1% cottonseed hulls, 10% whole cottonseed, 2% fish meal, 4% soybean meal, and 4.9% of a molasses, mineral, and vitamin supplement. Treatments were 40% sorghum grain either dry-rolled or steam-processed at flake densities of 437, 360, and 283 g/L. A fifth diet containing 42% dry-rolled barley was fed. Cows were blocked according to pretreatment (14 d) milk yield and received experimental diets for 56 d. Increasing ruminal starch degradability by including steam-flaked sorghum grain or barley in the diet did not increase milk yield or milk protein percentage and yield, as was shown in eight previous studies. Steam-flaked sorghum or dry-rolled barley in the diet decreased dry matter intake, resulting in a 10 to 19% higher efficiency of conversion of feed dry matter to milk than that for dry-rolled sorghum. Milk urea N was decreased, and milk casein yield tended to be increased, by steam-flaking sorghum at the moderate density compared with dry-rolling or fine flaking. Dietary protein was more efficiently converted to milk protein and casein from flaked sorghum and dry-rolled barley than from dry-rolled sorghum. In this study, increasing ruminal starch degradability resulted in higher feed efficiency and lower feed intakes, bu optimal flake densities for steam-processed sorghum gain to maximize milk and milk protein yield were not clarified.

  5. 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).

  6. An investigation of nanoscale grain boundary electrical activity and electrical properties in a model electroceramic: Niobium-doped strontium titanate

    NASA Astrophysics Data System (ADS)

    Johnson, Kevin David

    2000-12-01

    This thesis presents an integrated approach towards understanding grain boundary electrical properties in electroceramics by examining the effects of doping and annealing conditions on macroscopic electrical measurements, nanoscale potentials, and defect distributions at grain boundaries. The varistor behavior of a model electroceramic system, bicrystals of Nb bulk doped SrTiO 3, has been investigated as a basis for correlating grain boundary properties through a simplified microstructure. Although these bicrystals only have a single grain boundary, AC and DC electrical measurements have revealed a four order of magnitude increase in resistance for the isolated grain boundary. Characteristic of varistor behavior, this grain boundary resistance was demonstrated to rapidly decline above a switch-on voltage, indicating nonlinear grain boundary barrier breakdown. For the same bicrystals that showed varistor behavior, the characteristics of the grain boundary barrier were examined as a function of doping and heat treatment. SrTiO3 bicrystals, doped with donors (Nb) and acceptors (Mn), were examined with high resolution transmission electron microscopy techniques to observe changes in the local grain boundary chemistry and structure. Although Nb does not strongly segregate, through a Mn grain boundary doping procedure, highly doped grain boundaries were achieved. In both cases, electron holograms revealed the presence of potentials at these grain boundaries, indicative of the underlying charge density distributions. Another major contribution of this research has been the development of a unique procedure for incorporating in situ applied current with electron holography. This approach has enabled for the first time dynamic changes in grain boundary potentials to be directly observed as a function of applied bias. Although there remain many open-ended questions regarding the electrical activity of grain boundaries in even this simple electroceramic system, the thesis

  7. 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...

  8. Negligible effect of grain boundaries on the supercurrent density in polycrystalline MgB 2

    NASA Astrophysics Data System (ADS)

    Kim, Kijoon H. P.; Kang, W. N.; Kim, Mun-Seog; Jung, C. U.; Kim, Hyeong-Jin; Choi, Eun-Mi; Park, Min-Seok; Lee, Sung-Ik

    2002-04-01

    We used dc magnetization and transport measurement to estimate the superconducting critical current densities ( Jc) of polycrystalline MgB 2 sintered under high temperature and high pressure. We measured the current-voltage ( I-V) characteristics and found the existence of a vortex-glass phase in the field-temperature ( H-T) plane. This is notable in that the vortex-glass phase can be observed even in a polycrystalline specimen, which suggests that the supercurrent is not sensitive to the grain boundaries. Moreover, the transport (intergrain) Jc seems to be comparable to a magnetic (intragrain) Jc.

  9. Modulation of solar flare particles and track density profiles in gas-rich meteorite grains

    NASA Technical Reports Server (NTRS)

    Lee, M. A.

    1976-01-01

    A solution is presented to the problem concerning the time-averaged solar flare particle flux as a function of kinetic energy and distance from the sun for a given particle injection spectrum at the sun within the framework of standard diffusion-convection-adiabatic deceleration theory with the diffusion coefficient independent of distance from the sun. Results of the calculations which give best agreement with observations at 1 AU are presented and discussed, with particular reference to their implications for gas-rich meteorites. Normalization at the orbit of earth is achieved via observed track density versus depth profiles in lunar vug crystals. It is shown that if gas-rich meteorite grains were irradiated in the asteroid belt and if source and modulation parameters have changed little since irradiation, the track density should be 'harder' than the lunar vug profile by about 0.2-0.3 in the index. Quantitative estimation of solar flare particle exposure ages is discussed.

  10. Response of lactating dairy cows to various densities of sorghum grain.

    PubMed

    Santos, F A; Huber, J T; Theurer, C B; Swingle, R S; Simas, J M

    1997-06-01

    To examine the effects of various densities of sorghum grain resulting in graded levels of ruminally degradable starch on lactational performance, 32 lactating Holstein cows (90 d in milk [DIM]) were assigned to four treatments for 58 d. Diets contained 37% alfalfa hay, 3% cottonseed hulls, 10% whole cottonseed, 6% soybean meal, 5% of a molasses-mineral-vitamin supplement, and 39% sorghum grain. Treatments were dry-rolled sorghum (DRS) at 643 g/L or stream-flaked sorghum (SF) at 437, 360, and 283 g/L. Dry matter intake was highest for DRS followed by SF360, with the linear (P < .01) and cubic (P < .05) effects significant. The linear decrease in milk (P < .05) and 3.5% fat corrected milk (FCM, P < .025) with decreased density of sorghum was because of large decreases on SF283. Steam-flaking increased total tract digestibilities of DM, OM, CP, starch, and ADF when compared with dry-rolling. Efficiency of conversion of feed DM to FCM and feed CP to milk protein were greater for sorghum flaked at 437 and 360 g/L than for DRS or the 283 g/L flake. The 283 g/L flake decreased DMI, milk yield, and milk fat percentage. Addition of buffer (1% NaHCO3) tended to ameliorate the decrease in DMI. These data show greater efficiency of feed utilization and conversion of feed CP to milk protein in cows fed sorghum grain flaked at 437 and 360 g/L compared with those fed dry-rolled sorghum or that flaked at 283 g/L.

  11. Sorghum grain flake density and source of roughage in feedlot cattle diets.

    PubMed

    Theurer, C B; Swingle, R S; Wanderley, R C; Kattnig, R M; Urias, A; Ghenniwa, G

    1999-05-01

    Feedlot performance was studied in a 262-d trial using 126 crossbred beef steers (182 kg initial BW) to determine whether source of dietary roughage influences performance and carcass characteristics by steers fed growing (112 d) and finishing (150 d) diets with various flake densities (FD) of steam-processed sorghum grain. A 3 x 3 arrangement of treatments (two pens of seven steers each) was used, with dietary roughages being chopped alfalfa hay or 50:50 mixtures (equal NDF basis) of cotton-seed hulls or chopped wheat straw with alfalfa hay; sorghum grain was steam-flaked to densities of 386, 322, and 257 g/L (SF30, SF25, and SF20, reflecting bushel weight in pounds). The effects of these same FD on nutrient digestibilities were determined in three experiments with 24 crossbred steers fed finishing diets containing each of the roughage sources. No interactions between FD and roughage type were detected in any performance or carcass measurements (P > .10). Intake of DM decreased linearly (P < .05) in response to decreased FD. Daily rate and efficiency of gain were not altered (P >.10) by FD. Decreasing FD decreased linearly (P < .05) dressing percentage and fat thickness, but not other carcass measurements. Dietary roughage did not affect (P >.10) daily gains or carcass measurements, but DM intake was lower and feed efficiencies were superior (P < .05) when alfalfa hay was the sole source of roughage. Cottonseed hulls and wheat straw were relatively less valuable in the low roughage finishing diets than in higher roughage growing diets. Digestibilities of starch increased linearly as FD was decreased (P = .02) when steers were fed diets containing wheat straw, but not for alfalfa hay or cottonseed hull diets. Digestibilities of DM did not vary with changes in FD; however, changes in CP, NDF, and ADF digestibilities due to FD seemed to differ among experiments. In conclusion, performance and carcass measurement responses by growing-finishing steers to differences in

  12. Effect of the fused quartz particle density on nucleation and grain control of high-performance multicrystalline silicon ingots

    NASA Astrophysics Data System (ADS)

    Ding, Junjing; Yu, Yunyang; Chen, Wenliang; Zhou, Xucheng; Wu, Zhiyong; Zhong, Genxiang; Huang, Xinming

    2016-11-01

    The nucleation process of high-performance multicrystalline silicon (HP mc-Si) growth seeded by fused quartz particles (FQP) through directional solidification is crucial for the ingot quality. To determine the optimal density of FQP and obtain a better nucleation process and the grain growth, we cast ingots using four different densities of FQP fixed on the bottom of the four quartz crucibles and covered them with a certain thickness of Si3N4 coating. FQP sizes of 30-50 mesh were used, and the influence of the fused quartz particle density on the nucleation mechanism, initial grain uniformity, grain size, density of dislocation clusters, and cell efficiency were analyzed. Compared with the ingots seeded with other three densities of FQP, the 220 particles/cm2 of FQP seeded ingot showed better uniformity of nucleation and initial grains. A large number of small uniform Si grains with lower density of dislocation clusters in the bottom of the ingot were observed. The average conversion efficiency of p-type solar cells manufactured with the 220 particles/cm2 seeded ingot (18.28%) was 0.19% higher than that manufactured with the 120 particles/cm2 seeded ingot (18.09%).

  13. [Effects of tillage and straw returning on microorganism quantity, enzyme activities in soils and grain yield].

    PubMed

    Zhao, Ya-li; Guo, Hai-bin; Xue, Zhi-wei; Mu, Xin-yuan; Li, Chao-hai

    2015-06-01

    A two-year field study with split plot design was conducted to investigate the effects of different soil tillage (conventional tillage, CT; deep tillage, DT; subsoil tillage, ST) and straw returning (all straw retention, AS; no straw returning, NS) on microorganism quantity, enzyme activities in soil and grain yield. The results showed that, deep or subsoil tillage and straw returning not only reduced the soil bulk density and promoted the content of organic carbon in soil, but increased the soil microbial quantity, soil enzyme activities and grain yield. Furthermore, such influences in maize season were greater than that in wheat season. Compared with CT+NS, DT+AS and ST+AS decreased the soil bulk density at 20-30 cm depth by 8.5% and 6.6%, increased the content of soil organic carbon by 14.8% and 12.4%, increased the microorganism quantity by 45.9% and 33.9%, increased the soil enzyme activities by 34.1% and 25.5%, increased the grain yield by 18.0% and 19.3%, respectively. No significant difference was observed between DT+AS and ST+AS. We concluded that retaining crop residue and deep or subsoil tillage improved soil microorganism quantity, enzyme activities and crop yield.

  14. 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...

  15. Downstream lightening and upward heavying, sorting of sediments of uniform grain size but differing in density

    NASA Astrophysics Data System (ADS)

    Viparelli, E.; Solari, L.; Hill, K. M.

    2014-12-01

    Downstream fining, i.e. the tendency for a gradual decrease in grain size in the downstream direction, has been observed and studied in alluvial rivers and in laboratory flumes. Laboratory experiments and field observations show that the vertical sorting pattern over a small Gilbert delta front is characterized by an upward fining profile, with preferential deposition of coarse particles in the lowermost part of the deposit. The present work is an attempt to answer the following questions. Are there analogous sorting patterns in mixtures of sediment particles having the same grain size but differing density? To investigate this, we performed experiments at the Hydrosystems Laboratory at the University of Illinois at Urbana-Champaign. During the experiments a Gilbert delta formed and migrated downstream allowing for the study of transport and sorting processes on the surface and within the deposit. The experimental results show 1) preferential deposition of heavy particles in the upstream part of the deposit associated with a pattern of "downstream lightening"; and 2) a vertical sorting pattern over the delta front characterized by a pattern of "upward heavying" with preferential deposition of light particles in the lowermost part of the deposit. The observed downstream lightening is analogous of the downstream fining with preferential deposition of heavy (coarse) particles in the upstream part of the deposit. The observed upward heavying was unexpected because, considering the particle mass alone, the heavy (coarse) particles should have been preferentially deposited in the lowermost part of the deposit. Further, the application of classical fractional bedload transport relations suggests that in the case of mixtures of particles of uniform size and different densities equal mobility is not approached. We hypothesize that granular physics mechanisms traditionally associated with sheared granular flows may be responsible for the observed upward heavying and for the

  16. Increasing density leads to generalization in both coarse-grained habitat selection and fine-grained resource selection in a large mammal.

    PubMed

    van Beest, Floris M; Uzal, Antonio; Vander Wal, Eric; Laforge, Michel P; Contasti, Adrienne L; Colville, David; McLoughlin, Philip D

    2014-01-01

    Density is a fundamental driver of many ecological processes including habitat selection. Theory on density-dependent habitat selection predicts that animals should be distributed relative to profitability of habitat, resulting in reduced specialization in selection (i.e. generalization) as density increases and competition intensifies. Despite mounting empirical support for density-dependent habitat selection using isodars to describe coarse-grained (interhabitat) animal movements, we know little of how density affects fine-grained resource selection of animals within habitats [e.g. using resource selection functions (RSFs)]. Using isodars and RSFs, we tested whether density simultaneously modified habitat selection and within-habitat resource selection in a rapidly growing population of feral horses (Equus ferus caballus Linnaeus; Sable Island, Nova Scotia, Canada; 42% increase in population size from 2008 to 2012). Among three heterogeneous habitat zones on Sable Island describing population clusters distributed along a west-east resource gradient (west-central-east), isodars revealed that horses used available habitat in a density-dependent manner. Intercepts and slopes of isodars demonstrated a pattern of habitat selection that first favoured the west, which generalized to include central and east habitats with increasing population size consistent with our understanding of habitat quality on Sable Island. Resource selection functions revealed that horses selected for vegetation associations similarly at two scales of extent (total island and within-habitat zone). When densities were locally low, horses were able to select for sites of the most productive forage (grasslands) relative to those of poorer quality. However, as local carrying capacity was approached, selection for the best of available forage types weakened while selection for lower-quality vegetation increased (and eventually exceeded that of grasslands). Isodars can effectively describe coarse-grained

  17. 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).

  18. Related physicochemical properties to microstructure of hard and soft wheat grains with different kernel thickness and specific density.

    PubMed

    Li, Yinian; Wang, Jun; Xie, Weizhong; Lu, Daxin; Ding, Weimin

    2013-10-01

    Physicochemical properties of wheat grains with largest kernel thickness always was lowest than the other sections, examination of microstructure of wheat grains can help us understand this phenomena. Two varieties of wheat, soft white winter wheat Yangmai 11 and hard white winter wheat Zhengmai 9023, were fractionated into five sections by kernel thickness. Then the fractionated wheat grains in 2.7-3.0 mm section were separated into three fractions by kernel specific density sequentially. Microstructure of the fractured surface were evaluated at different scale level to two varieties wheat with different kernel thickness and specific density by using environmental scanning electron microscopy. Compactness and size of endosperm cell tended to decrease with decreasing wheat kernel thickness and specific density. Protein matrix tended to increase with decreasing wheat kernel thickness and specific density. Size of starch granules and proportion for different type starch granules also varied with different wheat kernel thickness and specific density. Those microstructure properties of the fractured surface, formation of endosperm cells, protein matrix and starch granules were close related to rheological properties and pasting properties of wheat grains.

  19. 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.

  20. Measurement of magnetic characteristics along arbitrary directions of grain-oriented silicon steel up to high flux densities

    SciTech Connect

    Nakata, T.; Takahashi, N.; Fujiwara, K.; Nakano, M. . Dept. of Electrical Engineering)

    1993-11-01

    A new technique for measuring B-H curves of grain-oriented silicon steel along arbitrary directions has been developed. As the control of waveform is not necessary in the new technique, it is possible to measure B-H curves up to high flux densities which are required for calculating flux distribution using the finite element method.

  1. 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).

  2. 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).

  3. Density of steam-flaked sorghum grain, roughage level, and feeding regimen for feedlot steers.

    PubMed

    Xiong, Y; Bartle, S J; Preston, R L

    1991-04-01

    Two hundred fifty-two steers (366 kg) were assigned to a 3 x 2 x 2 factorial arrangement of three densities of steam-flaked sorghum grain (bulk [flake] density of 437, 360, and 283 g/liter, B34, B28, and B22, respectively), two roughage levels (9 [R9] and 18% [R18]) and two feeding strategies (ad libitum [AD] or multiple of maintenance [MM], 2.3, 2.5, and 2.7 MM for wk 1, 2, and 3, and 2.9 MM thereafter). Steers fed R18-AD gained faster than steers fed R18-MM (1.59 vs 1.52 kg/d, P = .10); for R9 diets, no difference (P greater than .25) was found between steers fed AD and MM (interaction, P = .07). Flake density did not affect ADG (1.53 kg, P greater than .2). Dry matter intake decreased (9.8, 9.3, and 9.0 kg/d, linear, P less than .001) and gain efficiency (G/DMI, kg of gain/100 kg of DMI) increased (15.7, 16.5, and 16.9, linear, P less than .001; quadratic, P = .19) as processing degree increased (B34 to B22). Percentage of choice carcasses for B34 (67.0%) was higher (linear, P = .05) than for B28 (51.9%) and B22 (52.3%). Fecal starch and pH were 10.8, 5.7, and 4.0%, and 6.11, 6.23, and 6.37 for B34, B28, and B22, respectively (linear, P less than .001). The correlation between fecal starch and pH was -.51 (P less than .001, n = 252). Enzymatic glucose release, in vitro 6-h gas production, microbial protein synthesis, and protein degradability were 375, 483, and 559 mg/g; 24.7, 28.2, and 31.1 ml/.2 g; 6.15, 6.88, and 7.84 g/100g; and 61.4, 56.6, and 42.2% for B34, B28, and B22, respectively (linear, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Stress-free states of continuum dislocation fields: Rotations, grain boundaries, and the Nye dislocation density tensor

    NASA Astrophysics Data System (ADS)

    Limkumnerd, Surachate; Sethna, James P.

    2007-06-01

    We derive general relations between grain boundaries, rotational deformations, and stress-free states for the mesoscale continuum Nye dislocation density tensor. Dislocations generally are associated with long-range stress fields. We provide the general form for dislocation density fields whose stress fields vanish. We explain that a grain boundary (a dislocation wall satisfying Frank’s formula) has vanishing stress in the continuum limit. We show that the general stress-free state can be written explicitly as a (perhaps continuous) superposition of flat Frank walls. We show that the stress-free states are also naturally interpreted as configurations generated by a general spatially dependent rotational deformation. Finally, we propose a least-squares definition for the spatially dependent rotation field of a general (stressful) dislocation density field.

  5. Estimation of critical current density and grain connectivity in superconducting MgB 2 bulk using Campbell’s method

    NASA Astrophysics Data System (ADS)

    Ni, B.; Morita, Y.; Liu, Z.; Liu, C.; Himeki, K.; Otabe, E. S.; Kiuchi, M.; Matsushita, T.

    2008-09-01

    Many recent reports on the critical current density ( Jc) in superconducting MgB 2 bulks indicated that improving the grain connectivity is important, since the obtained Jc values were generally much lower than those in other metallic superconductors and it was ascribed to the poor connectivity between grains in polycrystalline MgB 2. In this study, we focused on the estimation of the global critical current density, super-current path, grain connectivity and their relationships with the faults volume fraction in the MgB 2 bulks prepared by a modified PIT (powder in tube) method. Campbell’s method was applied for the purpose of obtaining the penetrating AC flux profile and the characteristic of AC magnetic field vs. penetration depth from the sample’s surface. A computer simulation on the penetrating AC flux profile in MgB 2 bulks with randomly distributed voids, oxidized grains and other faults was also carried out. Jc obtained by Campbell’s method turned out to be smaller than that obtained from the SQUID measurement, implying that the global super-current was reduced by the existence of various faults and the lack of the electrical connectivity. It was verified that the relationship between the global critical current characteristics and the faults contained in MgB 2 samples can be quantitatively clarified by comparing the simulated critical current densities and other factors with the experimental results.

  6. 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

  7. Technical Note: Stored grain volume measurement using a low density point cloud

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mass of stored grain is often determined from volume measurements by crop insurers, government auditors, and stored grain managers conducting inventories. Recent increases in bin size have accentuated the difficulty of accounting for irregularities and variations in surface conditions in calcula...

  8. 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.

  9. Bioactive Components and Functional Properties of Biologically Activated Cereal Grains: A Bibliographic Review.

    PubMed

    Singh, Arashdeep; Sharma, Savita

    2015-10-14

    Whole grains provide energy, nutrients, fibres and bioactive compounds that may synergistically contribute to their protective effects. A wide range of these compounds is affected by germination. While some compounds, such as β-glucans are degraded, others, like antioxidants and total phenolics are increased by means of biological activation of grains. The water and oil absorption capacity as well as emulsion and foaming capacity of biologically activated grains are also improved. Application of biological activation of grains is of emerging interest, which may significantly enhance the nutritional, functional and bioactive content of grains, as well as improve palatability of grain foods in a natural way. Therefore, biological activation of cereals can be a way to produce food grains enriched with health promoting compounds and enhanced functional attributes.

  10. Hole density and capture of stored-product insect pests in grain probe traps.

    PubMed

    Epsky, Nancy D; Shuman, Dennis

    2002-12-01

    The relationship between number of holes in a grain probe trap body and capture of stored-grain pests was determined in laboratory tests using adults of the rice weevil, Sitophilus oryzae (L.), the sawtoothed grain beetle, Oryzaephilus surinamensis (L.), and the red flour beetle, Tribolium castaneum (Herbst). 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 60-492 holes, tested at 71 insects per kg in 2.8 kg of soft wheat in cylindrical mini-silos, sawtoothed grain beetle and rice weevil captures were directly related to number of holes in the probe trap body, but there was no relationship for red flour beetle capture. Subsequent tests were conducted comparing sawtoothed grain beetle and rice weevil captures in a PVC probe body with 210 holes over a 40-cm long trapping surface with two commercially available probe traps, a polycarbonate (Lexan) probe trap with 180 holes over a 14-cm long trapping surface and a polyethylene (WBII) probe trap with 750 holes over a 34-cm long trapping surface. The highest percentage capture of both species was in the WBII probe trap, but the 210-hole PVC probe body was as effective as the Lexan probe body for rice weevils and sawtoothed grain beetles at 71 and 17 insects per kg of wheat, respectively.

  11. 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.

  12. Dependence of grain size and defect density on the magnetic properties of mechanically alloyed Fe90W10 powder

    NASA Astrophysics Data System (ADS)

    Yamoah, N. K.; Koten, M. A.; Thompson, D.; Nannuri, C.; Narayan, J.; Shield, J. E.; Kumar, D.

    2016-10-01

    Mechanical alloying was used to synthesize nanocrystalline Fe90W10 powders from high purity Fe and W powders. X-ray diffraction measurements showed that the formation of BCC Fe-W solid solution occurred after 32 h of milling. The Scherrer-Debye and Williamson-Hall equations revealed that grain size reduction and defect creation were achieved during the milling process. There is a decrease of grain size from about 53 nm to about 6 nm after 80 h of milling. Williamson and Smallman's equation was also used to calculate the dislocation density. The result shows an increase in the dislocation density with increasing milling time. The grain size and defect characteristics were correlated with magnetic measurements. Magnetization versus magnetic field curves recorded using a vibrating sample magnetometer were utilized to obtain coercivity and saturation magnetization at different temperatures. As W is continually dissolved in the Fe lattice, the change in coercivity seems to be minimal until the completion of solid solution when there is a sudden increase in coercivity. The increase in coercivity is explained by an increase in anisotropy due to an additional source of anisotropy arising from strain during the milling process. There was also a decrease in saturation magnetization as a result of the grain size reduction.

  13. 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.

  14. 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...

  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 i...

  16. Correlation Between Grain and Grain-Boundary Critical Current Densities in ex situ Coated Conductors with Variable YBa2Cu3O7- δ Layer Thickness

    SciTech Connect

    Palau, A.; Puig, T.; Obradors, X.; Feenstra, Roeland; Gapud, Albert Agcaoili

    2006-01-01

    The dependence of the percolative critical current density at low magnetic fields on YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) layer thickness is studied by comparing grain, J{sub c}{sup G}, and grain-boundary, J{sub c}{sup GB}, critical current densities for a series of ex situ processed YBCO films on a RABiTS template. Both critical current densities decrease as a function of thickness and the values of J{sub c}{sup G} and J{sub c}{sup GB} show a clear correlation which suggests the existence of an interaction between Abrikosov-Josephson vortices on the grain boundaries and Abrikosov vortices in the bulk of the grains. This opens the possibility to improve J{sub c}{sup GB} by optimizing the pinning capabilities of the grains.

  17. 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.

  18. 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

  19. 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

  20. 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...

  1. 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...

  2. Effects of Seeding Rates and Rice Water Weevil (Coleoptera: Curculionidae) Density on Damage in Two Medium Grain Varieties of Rice.

    PubMed

    Aghaee, Mohammad-Amir; Espino, Luis; Goding, Kevin; Goldman, Evan; Godfrey, Larry D

    2016-04-01

    Rice water weevil (Lissorhoptrus oryzophilus Kuschel) is a common pest of rice production in the United States whose larvae cause yield loss by feeding on the roots. We conducted studies from 2011–2013 on M-202 and M-206, two commonly grown California medium grain rice varieties, to determine if M-206 demonstrated tolerance to rice water weevil damage. Observations from field studies suggested the possibility of a level of tolerance in M-206 that was more prevalent at high seeding rates. We did this study using two different experimental units, open and ring plots. In both units, we quantified grain yields across four levels, 56, 112, 168, and 224 kg/ha, of seeding rates to detect potential yield recovery by M-206. In the open plots, we used naturally occurring weevil populations compared with controls that reduced the populations with insecticides. In the ring plots, we tested three levels of weevil infestation, none, low, and high, to look at the weevil density effects on yield and scarred plants. Our studies showed that M-206 and M-202 had generally similar densities of immature weevils and yield. Compensation for yield loss did not occur at higher seeding rates. These results suggest that M-206 does not have the ability to tolerate rice water weevil damage better than M-202. There was weak evidence that the number of scarred plants increased as plant density was reduced. The results are discussed in relation to the utility of this study to grower choices of varieties for long-term rice water weevil management.

  3. Synchrotron radiation as a tool for in situ investigation of extraterrestrial grains in low-density collectors: application to the analyses of the PIE polymid foams targets

    NASA Astrophysics Data System (ADS)

    Borg, J.; Quirico, E.; Simionovici, A.; Raynal, P.-I.; Chevallier, P.; Langevin, Y.

    2002-08-01

    The Particle Impact Experiment (PIE) was flown for 11 months outside the MIR station in 1996-97. The grains, both of extraterrestrial and terrestrial origins, captured in the low-density foam collectors, were investigated for using Synchrotron X-ray microfluorescence (SXμF) techniques, developed at LURE (Orsay, France) and ESRF (Grenoble, France). The positions of grains a few microns large are known at better than 10 μm. Chemical identification is arduous; only Z>20 elements are identified and, for the heavy elements, only a rough estimate of their abundances inside the grains can be given. We use the Fe/Ni ratio as the criterion allowing to distinguish between terrestrial orbital debris (OD) and extraterrestrial grains. In the 60 cm2 of foam analyzed by this technique, we identified two or three probable extraterrestrial grains and confirmed the existence of an OD cloud, rich in Fe-Ni alloys, crossed by the MIR station. SXμF is a powerful, non-destructive, technique of in situ identification of absorbing grains trapped in a material otherwise transparent to X-rays. It is the only analytical procedure for foams, opaque to visible light. For aerogels, exposed in many space missions and used as grain collectors in the STARDUST mission, the grains positions can be known after an optical scanning; SXμF appears as the last step for the high resolution in situ identification (size, shape, chemical composition) of the grain before its eventual extraction by microtunneling techniques.

  4. 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

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

    PubMed

    Hämmerle, Martin; Höfle, Bernhard

    2014-12-16

    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.

  6. Reduced SnO2 Porous Nanowires with a High Density of Grain Boundaries as Catalysts for Efficient Electrochemical CO2 -into-HCOOH Conversion.

    PubMed

    Kumar, Bijandra; Atla, Veerendra; Brian, J Patrick; Kumari, Sudesh; Nguyen, Tu Quang; Sunkara, Mahendra; Spurgeon, Joshua M

    2017-03-20

    Electrochemical conversion of CO2 into energy-dense liquids, such as formic acid, is desirable as a hydrogen carrier and a chemical feedstock. SnOx is one of the few catalysts that reduce CO2 into formic acid with high selectivity but at high overpotential and low current density. We show that an electrochemically reduced SnO2 porous nanowire catalyst (Sn-pNWs) with a high density of grain boundaries (GBs) exhibits an energy conversion efficiency of CO2 -into-HCOOH higher than analogous catalysts. HCOOH formation begins at lower overpotential (350 mV) and reaches a steady Faradaic efficiency of ca. 80 % at only -0.8 V vs. RHE. A comparison with commercial SnO2 nanoparticles confirms that the improved CO2 reduction performance of Sn-pNWs is due to the density of GBs within the porous structure, which introduce new catalytically active sites. Produced with a scalable plasma synthesis technology, the catalysts have potential for application in the CO2 conversion industry.

  7. Critical current density and grain connectivity of Bi-2223 added MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Tripathi, D.; Dey, T. K.

    2014-04-01

    Polycrystalline MgB2 with addition of 0, 1, 3, and 5 wt. % of Bi-2223(Bi1.8Pb0.26Sr2Ca2Cu3O10+x) powder has been synthesized by solid reaction process. The effect of Bi-2223 addition on current transport and superconducting properties of polycrystalline MgB2 superconductor is discussed. Four probe DC resistivity measurement shows that low level of Bi-2223 addition hardly affects the superconducting transition temperature, Tc of MgB2. The modified Bloch- Gruneisen (B-G) analysis of normal state resistivity data reveals a decrease in intergrain connectivity and increase in intragrain connectivity of MgB2 by Bi-2223 addition. The critical current density of present set of samples is estimated from M- H hysteresis loop in the light of Bean's model. MgB2 added with 1 wt. % of Bi- 2223 added gives the best performance (˜ 2 times enhancement in Jc) amongst the studied samples.

  8. Microtwins and their effect on accumulation of excess dislocation density in grains with different types of crystal lattice bending in deformed austenitic steel

    SciTech Connect

    Gibert, Ivan; Kiseleva, Svetlana Popova, Natalya Koneva, Nina Kozlov, Eduard

    2016-01-15

    The investigation of excess dislocation density accumulation in the deformed polycrystalline austenitic steel was carried out using transmission electron microscopy (TEM). The distributions of the excess dislocation density in the grains of the deformed austenitic steel with different bending types were obtained and plotted. It was established that in the austenitic polycrystalline steel at the deformation degrees ε = 14 and 25 % the distributions of the excess dislocation density are multimodal. In both cases the grain with compound bending is more stressed. The values of the average excess dislocation density in the grains with the compound and simple bending are less at ε = 25 % than that at ε = 14 %. This is explained by a significant relaxation of the internal stresses in steel with the increase of the deformation degree from 14 % to 25 %. The increase of the number of twinning systems and the material volume fraction covered by twinning leads to the internal stress relaxation and consequently to the increase of the excess dislocation density. The presence of microtwins in the deformed material has an influence on the distribution of the excess dislocation density. In the deformed polycrystalline austenitic steel the number of grains with compound bending is increased with the increase of the plastic deformation degree.

  9. 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.

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

    PubMed

    de los Santos, Francisco; Franzese, Giancarlo

    2011-12-08

    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.

  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. 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.

  13. 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...

  14. Coarse-grained density functional theories for metallic alloys: Generalized coherent-potential approximations and charge-excess functional theory

    NASA Astrophysics Data System (ADS)

    Bruno, Ezio; Mammano, Francesco; Fiorino, Antonino; Morabito, Emanuela V.

    2008-04-01

    The class of the generalized coherent-potential approximations (GCPAs) to the density functional theory (DFT) is introduced within the multiple scattering theory formalism with the aim of dealing with ordered or disordered metallic alloys. All GCPA theories are based on a common ansatz for the kinetic part of the Hohenberg-Kohn functional and each theory of the class is specified by an external model concerning the potential reconstruction. Most existing DFT implementations of CPA-based theories belong to the GCPA class. The analysis of the formal properties of the density functional defined by GCPA theories shows that it consists of marginally coupled local contributions. Furthermore, it is shown that the GCPA functional does not depend on the details of the charge density and that it can be exactly rewritten as a function of the appropriate charge multipole moments to be associated with each lattice site. A general procedure based on the integration of the qV laws is described that allows for the explicit construction of the same function. The coarse-grained nature of the GCPA density functional implies a great deal of computational advantages and is connected with the O(N) scalability of GCPA algorithms. Moreover, it is shown that a convenient truncated series expansion of the GCPA functional leads to the charge-excess functional (CEF) theory [E. Bruno , Phys. Rev. Lett. 91, 166401 (2003)], which here is offered in a generalized version that includes multipolar interactions. CEF and the GCPA numerical results are compared with status of art linearized augmented plane wave (LAPW) full-potential density functional calculations for 62 bcc- and fcc-based ordered CuZn alloys, in all the range of concentrations. Two facts clearly emerge from these extensive tests. In the first place, the discrepancies between GCPA and CEF results are always within the numerical accuracy of the calculations, both for the site charges and the total energies. In the second place, the

  15. 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

    2014-07-01

    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.

  16. Increased grain boundary critical current density Jcgb by Pr-doping in pulsed laser-deposited Y1-xPrxBCO thin films

    NASA Astrophysics Data System (ADS)

    Irjala, M.; Huhtinen, H.; Awana, V. P. S.; Falter, M.; Paturi, P.

    2011-12-01

    A comparative study has been performed on Pr-doped Y1-x PrxBCO (x =0-0.20) thin films deposited by pulsed laser deposition on MgO and buffered NiW substrates to study the effect of Pr-doping on the grain boundary critical current density (Jcgb). Our earlier work on bulk materials and SrTiO3 substrates indicated that, whereas Pr increases Jc in bulk samples, it does not increase Jc in film samples without grain boundaries. In this work, we present increased Jc in low concentrations of Pr3+-doping (x < 0.04) at temperatures above 60 K in film samples on MgO substrates and at all temperatures and fields in film samples on buffered NiW substrates. Results indicate that Pr segregates into grain boundary regions, improving the local hole concentration and carrier density, hence, increasing Jcgb.

  17. 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 ...

  18. 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.

  19. The synthesis of lamellar nano MgB2 grains with nanoimpurities, flux pinning centers and their significantly improved critical current density.

    PubMed

    Ma, Zongqing; Liu, Yongchang; Cai, Qi

    2012-03-21

    MgB(2) superconductors with unique microstructures were rapidly fabricated at low temperatures, and exhibited significantly improved critical current density (J(c)). According to the microstructure observations, the prepared samples consisted of lamellar nano MgB(2) grains with many embedded nanoimpurities (about 10 nm). The formation of these lamellar nano MgB(2) grains is associated with the presence of a local Mg-Cu liquid at sintering temperatures as low as 575 °C. The ball milling treatment of the original powders also plays a positive role in the growth of lamellar grains. Based on an analysis of the relationship between resistivity and temperature, the lamellar nano MgB(2) grains in the prepared sample possess better grain connectivity than the typical morphology of MgB(2) samples prepared by traditional high-temperature sintering. Furthermore, the presence of many nano MgB(2) grain boundaries and nano impurities in the prepared sample can obviously increase the flux pinning centers in accordance with the analysis of flux pinning behavior. Both factors mentioned above contribute to the significant improvement in J(c) from low field to relative high field. The method developed in the present work is an effective and low-cost way to further enhance J(c) in MgB(2) superconductors across a wide range of applied magnetic fields without using expensive nanometer-sized dopants.

  20. 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

  1. 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.

  2. Evolution of grain structure and recombination active dislocations in extraordinary tall conventional and high performance multi-crystalline silicon ingots

    NASA Astrophysics Data System (ADS)

    Trempa, M.; Kupka, I.; Kranert, C.; Lehmann, T.; Reimann, C.; Friedrich, J.

    2017-02-01

    In this work one high performance multi-crystalline silicon ingot and one conventional multi-crystalline silicon ingot, each with an extraordinary ingot height of 710 mm, were replicated by the successive growth of eight G1 ingots to evaluate the potential advantage of extraordinary tall HPM ingots in industrial production. By analyzing different grain structure parameters like mean grain size, grain orientation and grain boundary type distribution as well as the recombination active dislocation area over the complete ingot height, it was observed that the material properties strongly differ in the initial state of growth for the two material types. However, at ingot heights above 350 mm, the difference has vanished and the grain structure properties for both materials appear similar. It is shown that the evolution of the grain structure in both material types can be explained by the same grain selection and grain boundary generation/annihilation mechanisms whereas the current grain structure determines which mechanisms are the most dominant at a specific ingot height. Since the grain structure directly influences the dislocation content in the silicon material, also the recombination active dislocation area becomes equal in high performance and conventional multi-crystalline silicon material at ingot heights above 350 mm. From these results it is concluded that the advantage of high performance silicon material is limited to the first grown 350 mm of the ingot.

  3. 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…

  4. 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.

  5. 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.

  6. 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.

  7. Roles of grain boundaries in improving fracture toughness of ultrafine-grained metals

    NASA Astrophysics Data System (ADS)

    Shimokawa, T.; Tanaka, M.; Kinoshita, K.; Higashida, K.

    2011-06-01

    In order to improve the fracture toughness in ultrafine-grained metals, we investigate the interactions among crack tips, dislocations, and grain boundaries in aluminum bicrystal models containing a crack and <112> tilt grain boundaries using molecular dynamics simulations. The results of previous computer simulations showed that grain refinement makes materials brittle if grain boundaries behave as obstacles to dislocation movement. However, it is actually well known that grain refinement increases fracture toughness of materials. Thus, the role of grain boundaries as dislocation sources should be essential to elucidate fracture phenomena in ultrafine-grained metals. A proposed mechanism to express the improved fracture toughness in ultrafine-grained metals is the disclination shielding effect on the crack tip mechanical field. Disclination shielding can be activated when two conditions are present. First, a transition of dislocation sources from crack tips to grain boundaries must occur. Second, the transformation of grain-boundary structure into a neighboring energetically stable boundary must occur as dislocations are emitted from the grain boundary. The disclination shielding effect becomes more pronounced as antishielding dislocations are continuously emitted from the grain boundary without dislocation emissions from crack tips, and then ultrafine-grained metals can sustain large plastic deformation without fracture with the drastic increase of the mobile dislocation density. Consequently, it can be expected that the disclination shielding effect can improve the fracture toughness in ultrafine-grained metals.

  8. 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.

  9. 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.

  10. ON THE ACTIVE REGION BRIGHT GRAINS OBSERVED IN THE TRANSITION REGION IMAGING CHANNELS OF IRIS

    SciTech Connect

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

    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{sup −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.

  11. Dust Grains and the Luminosity of Circumnuclear Water Masers in Active Galaxies

    NASA Technical Reports Server (NTRS)

    Collison, Alan J.; Watson, William D.

    1995-01-01

    In previous calculations for the luminosities of 22 GHz water masers, the pumping is reduced and ultimately quenched with increasing depth into the gas because of trapping of the infrared (approximately equals 30-150 micrometers), spectral line radiation of the water molecule. When the absorption (and reemission) of infrared radiation by dust grains is included, we demonstrate that the pumping is no longer quenched but remains constant with increasing optical depth. A temperature difference between the grains and the gas is required. Such conditions are expected to occur, for example, in the circumnuclear masing environments created by X-rays in active galaxies. Here, the calculated 22 GHz maser luminosities are increased by more than an order of magnitude. Application to the well-studied, circumnuclear masing disk in the galaxy NGC 4258 yields a maser luminosity near that inferred from observations if the observed X-ray flux is assumed to be incident onto only the inner surface of the disk.

  12. 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

  13. Photospheric Magnetic Free Energy Density of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Zhang, Hongqi

    2016-12-01

    We present the photospheric energy density of magnetic fields in two solar active regions (one of them recurrent) inferred from observational vector magnetograms, and compare it with other available differently defined energy parameters of magnetic fields in the photosphere. We analyze the magnetic fields in Active Regions NOAA 6580-6619-6659 and 11158. The quantity 1/4π{B}n\\cdot{B}p is an important energy parameter that reflects the contribution of magnetic shear to the difference between the potential (Bp) and the non-potential magnetic field (Bn), and also the contribution to the free magnetic energy near the magnetic neutral lines in the active regions. It is found that the photospheric mean magnetic energy density shows clear changes before the powerful solar flares in Active Region NOAA 11158, which is consistent with the change in magnetic fields in the flaring lower atmosphere.

  14. Density of Plutonium Turnings Generated from Machining Activities

    SciTech Connect

    Gonzales, John Robert; Vigil, Duane M.; Jachimowski, Thomas A.; Archuleta, Alonso; Arellano, Gerald Joseph; Melton, Vince Lee

    2016-10-20

    The purpose of this project was to determine the density of plutonium (Pu) turnings generated from the range of machining activities, using both surrogate material and machined Pu turnings. Verify that 500 grams (g) of plutonium will fit in a one quart container using a surrogate equivalent volume and that 100 grams of Pu will fit in a one quart Savy container.

  15. Flag leaf photosynthesis and stomatal function of grain sorghum as influenced by changing photosynthetic photon flux densities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data on physiological parameters of A, gs, Em, Ci, and IWUE in grain sorghum (Sorghum bicolor L. Moench) is limited. Flag leaves from three plants of two hybrids, grown using added N fertilizer rates of 0.0, 112, and 224 kg ha-1 near Elizabeth, MS were field sampled for these parameters at growth s...

  16. Density and Temperature Measurements in a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Winebarger, Amy R.

    2003-10-01

    We present electron density and temperature measurements from an active region observed above the limb with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory. Density-sensitive line ratios from Si VIII and S X indicate densities greater than 108 cm-3 as high as 200" (or 145 Mm) above the limb. At these heights, static, uniformly heated loop models predict densities close to 107 cm-3. Differential emission measure analysis shows that the observed plasma is nearly isothermal with a mean temperature of about 1.5 MK and a dispersion of about 0.2 MK. Both the differential emission measure and the Si XI/Si VIII line ratios indicate only small variations in the temperature at the heights observed. These measurements confirm recent observations from the Transition Region and Coronal Explorer of ``overdense'' plasma at temperatures near 1 MK in solar active regions. Time-dependent hydrodynamic simulations suggest that impulsive heating models can account for the large densities, but they have a difficult time reproducing the narrow range of observed temperatures. The observations of overdense, nearly isothermal plasma in the solar corona provide a significant challenge to theories of coronal heating.

  17. Antioxidant Activity of Individual Steryl Ferulates from Various Cereal Grain Sources.

    PubMed

    Zhu, Dan; Sánchez-Ferrer, Antoni; Nyström, Laura

    2016-02-26

    Steryl ferulates (SFs) are a subclass of bioactive lipids contributing to the health-promoting effects of whole grains. Most related studies focus on γ-oryzanol, a SF mixture from rice, since individual steryl ferulates are not commercially available. There is little evidence that individual SFs may vary in their bioactivity. The aim of this study was to evaluate the antioxidant activity of eight individual SFs by determining their radical scavenging capacity. Additional molecular properties of the individual SFs were determined by molecular simulation in order to identify correlations with their antioxidant activities. Our study demonstrates that individual SFs exhibit 1,1-diphenyl-2-picrylhydrazyl radical, hydroxyl radical, and superoxide anion radical scavenging abilities with subtle differences that were highly dependent on the kind of reaction taking place. The grouping of SFs by principle component analysis was mainly attributed to molecular properties, not antioxidant activities. Solvation energy was significantly correlated with some experimental observations. To our knowledge, this is the first study to evaluate the antioxidant activity of eight individual steryl ferulates from different sources. Results of this work will provide better insight into the antioxidant activity of SFs and the health benefits of whole grains.

  18. Reduction of pyruvate orthophosphate dikinase activity is associated with high temperature-induced chalkiness in rice grains.

    PubMed

    Wang, Zhen-mei; Li, Hai-xia; Liu, Xiong-feng; He, Ying; Zeng, Han-lai

    2015-04-01

    Global warming affects both rice (Oryza sativa) yields and grain quality. Rice chalkiness due to high temperature during grain filling would lower the grain quality. The biochemical and molecular mechanisms responsible for the increased occurrence of chalkiness under high temperature are not fully understood. Previous research suggested that cytosolic pyruvate orthophosphate dikinase (cyPPDK, EC 2.7.9.1) in rice modulates carbon metabolism. The objective of this study was to determine the relationship between cyPPDK and high temperature-induced chalkiness. High temperature treatments were applied during the grain filling of two rice cultivars (9311 and TXZ-25) which had different sensitivity of chalkiness to high temperature. Chalkiness was increased significantly under high temperature treatment, especially for TXZ-25. A shortened grain filling duration and a decreased grain weight in both cultivars were caused by high temperature treatment. A reduction in PPDK activities due to high temperature was observed during the middle and late grain filling periods, accompanied by down regulated cyPPDK mRNA and protein levels. The temperature effects on the developmental regulation of PPDK activity were confirmed at transcription, translation and post-translational levels. PPDK activities were insensitive to variation in PPDK levels, suggesting the rapid phosphorylation mechanism of this protein. The two varieties showed similar responses to the high temperature treatment in both PPDK activities and chalkiness. We concluded that high temperature-induced chalkiness was associated with the reduction of PPDK activity.

  19. 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.

  20. Density functional theory metadynamics of silver, caesium and palladium diffusion at β-SiC grain boundaries

    NASA Astrophysics Data System (ADS)

    Rabone, Jeremy; López-Honorato, Eddie

    2015-03-01

    The use of silicon carbide in coated nuclear fuel particles relies on this materials impermeability towards fission products under normal operating conditions. Determining the underlying factors that control the rate at which radionuclides such as Silver-110m and Caesium-137 can cross the silicon carbide barrier layers, and at which fission products such as palladium could compromise or otherwise alter the nature of this layer, are of paramount importance for the safety of this fuel. To this end, DFT-based metadynamics simulations are applied to the atomic diffusion of silver, caesium and palladium along a Σ5 grain boundary and to palladium along a carbon-rich Σ3 grain boundary in cubic silicon carbide at 1500 K. For silver, the calculated diffusion coefficients lie in a similar range (7.04 × 10-19-3.69 × 10-17 m2 s-1) as determined experimentally. For caesium, the calculated diffusion rates are very much slower (3.91 × 10-23-2.15 × 10-21 m2 s-1) than found experimentally, suggesting a different mechanism to the simulation. Conversely, the calculated atomic diffusion of palladium is very much faster (7.96 × 10-11-7.26 × 10-9 m2 s-1) than the observed penetration rate of palladium nodules. This points to the slow dissolution and rapid regrowth of palladium nodules as a possible ingress mechanism in addition to the previously suggested migration of entire nodules along grain boundaries. The diffusion rate of palladium along the Σ3 grain boundary was calculated to be slightly slower (2.38 × 10-11-8.24 × 10-10 m2 s-1) than along the Σ5 grain boundary. Rather than diffusing along the precise plane of the boundary, the palladium atom moves through the bulk layer immediately adjacent to the boundary as there is greater freedom to move.

  1. Antioxidative activities and phenolic compounds of pumpkin (Cucurbita pepo) seeds and amaranth (Amaranthus caudatus) grain extracts.

    PubMed

    Peiretti, Pier Giorgio; Meineri, Giorgia; Gai, Francesco; Longato, Erica; Amarowicz, Ryszard

    2017-01-23

    Phenolic compounds were extracted from pumpkin (Cucurbita pepo) seed and amaranth (Amaranthus caudatus) grain into 80% (v/v) methanol. The extracts obtained were characterised by the contents of total phenolic compounds (TPC), trolox equivalent antioxidant capacity (TEAC), ferric-reducing antioxidant power (FRAP) and antiradical activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH(·)) radical. The content of individual phenolic compounds was determined by HPLC-DAD method. Pumpkin seeds showed the higher content of TPC than that from amaranth. The TEAC values of both extracts were similar each other. The lower value of FRAP was observed for pumpkin seed. Phenolic compound present in amaranth grain exhibited strongest antiradical properties against DPPH radical. Several peaks were present on the HPLC chromatograms of two extracts. The UV-DAD spectra confirmed the presence of vanillic acid derivatives in the amaranth grain. The three main phenolic compound present in pumpkin seed were characterised by UV-DAD spectra with maximum at 258, 266 and 278 nm.

  2. Slip Activity in Single Grains Extracted from Polycrystalline Specimen by X-Ray Line Broadening (Preprint)

    DTIC Science & Technology

    2010-01-01

    4 6 8 0.005 0.010 -101-3 -110-2 1-10-2F W H M [ 1 /n m ] K [ 1/nm ] Gr #44 Gr #50 Gr #72 -101-1 1-101 (a...0 2 4 6 0.000 0.005 0.010 (b) K2Ccalc [ 1/nm ] FW H M [ 1 /n m ] Gr #44 Gr #50 Gr #72 17 Figure 5. The FWHM (in 1/nm scales) in...Preprint 01 January 2010 – 01 January 2010 4 . TITLE AND SUBTITLE SLIP ACTIVITY IN SINGLE GRAINS EXTRACTED FROM POLYCRYSTALLINE SPECIMEN BY X-RAY

  3. Mold-inhibitory activity of different yeast species during airtight storage of wheat grain.

    PubMed

    Adel Druvefors, Ulrika; Schnürer, Johan

    2005-02-01

    The yeast Pichia anomala J121 inhibits spoilage by Penicillium roqueforti in laboratory and pilot studies with high-moisture wheat in malfunctioning airtight storage. We tested the biocontrol ability of an additional 57 yeast species in a grain mini silo system. Most yeast species grew to CFU levels comparable to that of P. anomala J121 after 14 days of incubation (>10(6) CFU g(-1)). Of the 58 species, 38 (63 strains) had no mold-inhibitory effects (Pen. roqueforti levels >10(5) CFU g(-1)). Among these were 11 species (18 strains) that did not grow on the wheat grain. Several of the non-inhibiting yeast species have previously been reported as biocontrol agents in other postharvest environments. Weak inhibitory activity, reducing Pen. roqueforti levels to between 10(4) and 10(5) CFU g(-1), was observed with 11 species (12 strains). Candida silvicola and Pichia guillermondii reduced Pen. roqueforti to <10(4) CFU g(-1). Candida fennica, Candida pelliculosa, Candida silvicultrix, P. anomala (29 strains), Pichia burtonii, Pichia farinosa and Pichia membranifaciens strongly inhibited Pen. roqueforti (<10(3) CFU g(-1)) in the mini silos, but none had higher biocontrol activity than P. anomala strain J121. This report is the first of biocontrol activity of C. fennica and C. silvicultrix. The ability of 27 yeast species to grow to high CFU values without inhibiting mold growth suggests that nutrient competition may not be the main mode of action of P. anomala J121.

  4. NADPH oxidase activity in allergenic pollen grains of different plant species.

    PubMed

    Wang, Xiao-Ling; Takai, Toshiro; Kamijo, Seiji; Gunawan, Hendra; Ogawa, Hideoki; Okumura, Ko

    2009-09-25

    Pollen is an important trigger of allergic diseases. Recent studies have shown that ragweed pollen NAD(P)H oxidase generates reactive oxygen species (ROS) and plays a prominent role in the pathogenesis of allergies in mouse models. Here, we demonstrated that allergenic pollen grains showed NAD(P)H oxidase activity that differed in intensity and localization according to the plant families. The activity occurred at the surface or in the cytoplasm in pollen of grasses, birch, and ragweed; in subpollen particles released from ragweed pollen; and at the inner surface or in the cytoplasm but not on the outer wall, which was sloughed off after the rupture, of pollen of Japanese cedar and Japanese cypress. The activity was mostly concentrated within insoluble fractions, suggesting that it facilitates the exposure of tissues to ROS generated by this enzyme. The extent of exposure to pollen-generated ROS could differ among the plant families.

  5. Release and Activity of Bound beta-Amylase in a Germinating Barley Grain.

    PubMed

    Sopanen, T; Laurière, C

    1989-01-01

    In resting grains of Triumph barley (Hordeum vulgare L. cv Triumph) about 40% of the beta-amylase could be extracted with a saline solution, the remaining 60% being in a bound form. During seedling growth (20 degrees C), the bound form was released mainly between days 1 and 3. When a preparation containing bound beta-amylase was incubated with an extract made of endosperms separated from germinating grains, release of bound beta-amylase took place and could be studied in vitro. The release was almost completely prevented by leupeptin and antipain, specific inhibitors of a group of SH-proteinases, but it was not inhibited by pepstatin A or EDTA, which inhibit some other barley proteinases. It is thus very likely that in a whole grain, at least the bulk of the bound beta-amylase is released by the proteolytic action of one or several SH-proteinases. When the bound beta-amylase was released by papain, its molecular weight was about 5000 daltons smaller than that of beta-amylase released by dithiothreitol. This indicates that the release is due to removal of a sequence of beta-amylase itself. A similar decrease in size took place during seedling growth. Bound beta-amylase showed some activity against native starch and it hydrolyzed maltotetraose at a rate that was about 70% of the rate the same amount of bound beta-amylase gave after release. Bound beta-amylase is thus not inactive and it is likely that the slower rate of hydrolysis is due to steric hindrances which prevent substrates from reaching the active site.

  6. 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).

  7. 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.

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

    PubMed

    Nilthong, Somrudee; Graybosch, R A; Baenziger, P S

    2012-12-01

    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 markers, PPO18, PPO29 and STS01, were used to identify lines with putative alleles at the Ppo-A1 and Ppo-D1 loci conditioning low or high PPO activity. ANOVA showed significant genotypic effects on PPO activity (P < 0.0001) in all populations. The generations and generation × genotype effects were not significant in any population. A putative third (null) genotype at Ppo-A1 (no PCR fragments for PPO18) was discovered in NW07OR1066 and NW07OR1070 derived populations, and these had the lowest mean PPO activities. Results demonstrated that both Ppo-A1 and Ppo-D1 loci affect the kernel PPO activity, but the Ppo-A1 has the major effect. In three populations, contrary results were observed to those predicted from previous work with Ppo-D1 alleles, suggesting the markers for Ppo-D1 allele might give erroneous results in some genetic backgrounds or lineages. Results suggest that selection for low or null alleles only at Ppo-A1 might allow development of low PPO wheat cultivars.

  9. 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.

  10. 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

  11. Infection of Ustilaginoidea virens intercepts rice seed formation but activates grain-filling-related genes.

    PubMed

    Fan, Jing; Guo, Xiao-Yi; Li, Liang; Huang, Fu; Sun, Wen-Xian; Li, Yan; Huang, Yan-Yan; Xu, Yong-Ju; Shi, Jun; Lei, Yang; Zheng, Ai-Ping; Wang, Wen-Ming

    2015-06-01

    Rice false smut has become an increasingly serious disease in rice (Oryza sativa L.) production worldwide. The typical feature of this disease is that the fungal pathogen Ustilaginoidea virens (Uv) specifically infects rice flower and forms false smut ball, the ustiloxin-containing ball-like fungal colony, of which the size is usually several times larger than that of a mature rice seed. However, the underlying mechanisms of Uv-rice interaction are poorly understood. Here, we applied time-course microscopic and transcriptional approaches to investigate rice responses to Uv infection. The results demonstrated that the flower-opening process and expression of associated transcription factors, including ARF6 and ARF8, were inhibited in Uv-infected spikelets. The ovaries in infected spikelets were interrupted in fertilization and thus were unable to set seeds. However, a number of grain-filling-related genes, including seed storage protein genes, starch anabolism genes and endosperm-specific transcription factors (RISBZ1 and RPBF), were highly transcribed as if the ovaries were fertilized. In addition, critical defense-related genes like NPR1 and PR1 were downregulated by Uv infection. Our data imply that Uv may hijack host nutrient reservoir by activation of the grain-filling network because of growth and formation of false smut balls.

  12. 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.

  13. 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.

  14. Cytokinin activity increases stomatal density and transpiration rate in tomato

    PubMed Central

    Farber, Mika; Attia, Ziv; Weiss, David

    2016-01-01

    Previous studies on cytokinin (CK) and drought have suggested that the hormone has positive and negative effects on plant adaptation to restrictive conditions. This study examined the effect of CK on transpiration, stomatal activity, and response to drought in tomato (Solanum lycopersicum) plants. Transgenic tomato plants overexpressing the Arabidopsis thaliana CK-degrading enzyme CK oxidase/dehydrogenase 3 (CKX3) maintained higher leaf water status under drought conditions due to reduced whole-plant transpiration. The reduced transpiration could be attributed to smaller leaf area and reduced stomatal density. CKX3-overexpressing plants contained fewer and larger pavement cells and fewer stomata per leaf area than wild-type plants. In addition, wild-type leaves treated with CK exhibited enhanced transpiration and had more pavement cells and increased numbers of stomata per leaf area than untreated leaves. Manipulation of CK levels did not affect stomatal movement or abscisic acid-induced stomatal closure. Moreover, we found no correlation between stomatal aperture and the activity of the CK-induced promoter Two-Component Signaling Sensor (TCS) in guard cells. Previous studies have shown that drought reduces CK levels, and we propose this to be a mechanism of adaptation to water deficiency: the reduced CK levels suppress growth and reduce stomatal density, both of which reduce transpiration, thereby increasing tolerance to prolonged drought conditions. PMID:27811005

  15. Cytokinin activity increases stomatal density and transpiration rate in tomato.

    PubMed

    Farber, Mika; Attia, Ziv; Weiss, David

    2016-12-01

    Previous studies on cytokinin (CK) and drought have suggested that the hormone has positive and negative effects on plant adaptation to restrictive conditions. This study examined the effect of CK on transpiration, stomatal activity, and response to drought in tomato (Solanum lycopersicum) plants. Transgenic tomato plants overexpressing the Arabidopsis thaliana CK-degrading enzyme CK oxidase/dehydrogenase 3 (CKX3) maintained higher leaf water status under drought conditions due to reduced whole-plant transpiration. The reduced transpiration could be attributed to smaller leaf area and reduced stomatal density. CKX3-overexpressing plants contained fewer and larger pavement cells and fewer stomata per leaf area than wild-type plants. In addition, wild-type leaves treated with CK exhibited enhanced transpiration and had more pavement cells and increased numbers of stomata per leaf area than untreated leaves. Manipulation of CK levels did not affect stomatal movement or abscisic acid-induced stomatal closure. Moreover, we found no correlation between stomatal aperture and the activity of the CK-induced promoter Two-Component Signaling Sensor (TCS) in guard cells. Previous studies have shown that drought reduces CK levels, and we propose this to be a mechanism of adaptation to water deficiency: the reduced CK levels suppress growth and reduce stomatal density, both of which reduce transpiration, thereby increasing tolerance to prolonged drought conditions.

  16. Antioxidant activity in barley (Hordeum Vulgare L.) grains roasted in a microwave oven under conditions optimized using response surface methodology.

    PubMed

    Omwamba, Mary; Hu, Qiuhui

    2010-01-01

    Microwave processing and cooking of foods is a recent development that is gaining momentum in household as well as large-scale food applications. Barley contains phenol compounds which possess antioxidant activity. In this study the microwave oven roasting condition was optimized to obtain grains with high antioxidant activity measured as the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. Antioxidant activity of grains roasted under optimum conditions was assessed based on DPPH radical scavenging activity, reducing power and inhibition of oxidation in linoleic acid system. The optimum condition for obtaining roasted barley with high antioxidant activity (90.5% DPPH inhibition) was found to be at 600 W microwave power, 8.5 min roasting time, and 61.5 g or 2 layers of grains. The roasting condition influenced antioxidant activity both individually and interactively. Statistical analysis showed that the model was significant (P < 0.0001). The acetone extract had significantly high inhibition of lipid peroxidation and DPPH radical scavenging activity compared to the aqueous extract and alpha-tocopherol. The reducing power of acetone extracts was not significantly different from alpha-tocopherol. The acetone extract had twice the amount of phenol content compared to the aqueous extract indicating its high extraction efficiency. GC-MS analysis revealed the presence of phenol acids, amino phenols, and quinones. The aqueous extract did not contain 3,4-dihydroxybenzaldehyde and 4-hydroxycinnamic acid which are phenol compounds reported to contribute to antioxidant activity in barley grain.

  17. 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

  18. 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

    2015-07-07

    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.

  19. Factors affecting laboratory bioassays with diatomaceous earth on stored wheat: effect of insect density, grain quantity, and cracked kernel containment.

    PubMed

    Kavallieratos, Nickolas G; Athanassiou, Christos G; Mpakou, Flora D; Mpassoukou, Argyro E

    2007-10-01

    Laboratory bioassays were carried out to evaluate the effect of insect density (10, 30, 60, and 100 adults), wheat quantity (10, 30, 60, and 100 g), and cracked kernel containment (5, 15, 30, and 50%) on the efficacy of diatomaceous earth (DE). Three beetle species, Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Tribolium confusum Jacquelin du Val, as well as two DE formulations, Insecto and SilicoSec, and one DE enhanced with pyrethrum, PyriSec (all commercially available) were tested. In the first two series of bioassays, the three DE formulations were applied at three dose rates, 500, 1000 and 1,500 ppm. In the third series, the dose rates used were 500 and 1,000 ppm. Dead adults were counted 14 d later. For insect density, wheat quantity, and cracked kernel containment, significant differences were noted in mortality levels of the tested species among the three DE formulations and among doses. No significant differences were noted in the mortality levels among the four adult densities of any of the insects tested. The increase of wheat quantity used in the bioassays increased significantly adult mortality of T. confusum. The increase of cracked wheat containment decreased significantly adult mortality of S. oryzae.

  20. 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.

  1. Steam-processed corn and sorghum grain flaked at different densities alter ruminal, small intestinal, and total tract digestibility of starch by steers.

    PubMed

    Theurer, C B; Lozano, O; Alio, A; Delgado-Elorduy, A; Sadik, M; Huber, J T; Zinn, R A

    1999-10-01

    Crossbred steers (n = 7; 400 kg BW), fitted with T-type cannulas in the duodenum and ileum, were used to examine the effects of processing method, dry-rolled (DR) vs. steam-flaked (SF) sorghum grain, and degree of processing (flake density; FD) of SF corn (SFC) and SF sorghum (SFS) grain on site and extent of DM, starch, and N digestibilities and to measure extent of microbial N flow to the duodenum. In Exp. 1, diets contained 77% DRS or 77% SFS with FD of 437, 360, and 283 g/L (SF34, SF28, and SF22). In Exp. 2, diets contained 77% SFC with FD of SF34 or SF22. For sorghum and corn diets, respective average daily intakes were as follows: DM, 6.7 and 8.1 kg; starch, 3.8 and 4.7 kg; N, 136 and 149 g. Steers fed SFS vs. DRS increased (P = .01) starch digestibilities (percentage of intake) in the rumen (82 vs. 67%) and total tract (98.9 vs. 96.5%) and decreased digestibilities in the small intestine (16 vs. 28%; P = .01) and large intestine (.5 vs 1.2%; P = .05). As a percentage of starch entering the segment, digestibility was increased (P = .01) within the small intestine (91 vs. 85%) but was not altered within the large intestine by steers fed SFS vs. DRS. Decreasing FD of SFS and of SFC, respectively, linearly increased starch digestibilities (percentage of intake) in the rumen (P = .03, .02) and total tract (P = .03, .09) and linearly diminished starch digestibilities in the small intestine (P = .04, .09). Starch digestibilities (percentage of entry) within the small or large intestine were not changed by FD. The percentage of dietary corn or sorghum starch digested in the large intestine was very small, less than 2% of intake. Microbial N flow to the duodenum was not altered by SFS compared to DRS, or by decreasing FD of SFS and SFC. Reducing FD of SFS, but not of SFC, tended to decrease (P = .07) microbial efficiency linearly and tended to increase (P = .06) total tract N digestibilities linearly. Steam flaking compared to dry rolling of sorghum grain and

  2. 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

  3. Dust grains in the coma of 67P/Churyumov-Gerasimenko - link with surface properties and cometary activity

    NASA Astrophysics Data System (ADS)

    Capria, Maria Teresa; Ivanovski, Stavro; Zakharov, Vladimir; Capaccioni, Fabrizio; Filacchione, Gianrico; De Sanctis, Maria Cristina; rotundi, alessandra; della corte, vincenzo; Longobardo, Andrea; Palomba, Ernesto; colangeli, luigi; Bockelee-Morvan, Dominique; Érard, Stéphane; Leyrat, Cedric; VIRTIS, GIADA

    2016-10-01

    The imaging spectrometer VIRTIS and the dust analyzer GIADA, onboard Rosetta, made an extensive observation of the dust particles in the coma of the comet 67P/Churyumov-Gerasimenko. From the analysis of GIADA data, two different kind of particles have been revealed, compact and fluffy with different compositions and dynamical properties. Compact particles are characterized by densities of about 103 kg/m3, while fluffy particles have an almost fractal nature, with densities less than 1 kg/m3.In this work we present the initial results of a model linking the dust flux distribution, as obtained from a theoretical thermal nucleus model, with a model describing the dynamics of aspherical grains in the coma. The results are discussed in the context of the latest observations from VIRTIS and GIADA instruments.The 2D nucleus thermal model, when applied to the real shape of the comet, provides the size distribution and physical properties of the emitted grains at different times and location on the surface. The thermal model can simulate grains of various size distribution, composition and physical properties. This information is used as an input for the dust dynamical model that follows the emitted particles in the coma. The main source of heating is the solar illumination. In the dust dynamical model, the grain trajectory of emitted particles remains in a plane perpendicular to the rotational axis and the direction of illumination is taken to be in the same plane (i.e. does not cause transversal forces). The dust particles are assumed to be isothermal convex bodies and temperature changes only induce modest changes in the aerodynamic force (twice higher temperature changes aerodynamic force less than ~30%). This study reviews the theoretical values at which temperature difference starts to play a role on the dynamics. We discuss to what extent the particle's temperature affects the terminal velocities of the dust grains in the 67P coma in dependence on their mass and

  4. Bio-oil and bio-char from low temperature pyrolysis of spent grains using activated alumina.

    PubMed

    Sanna, Aimaro; Li, Sujing; Linforth, Rob; Smart, Katherine A; Andrésen, John M

    2011-11-01

    The pyrolysis of wheat and barley spent grains resulting from bio-ethanol and beer production respectively was investigated at temperatures between 460 and 540 °C using an activated alumina bed. The results showed that the bio-oil yield and quality depend principally on the applied temperature where pyrolysis at 460 °C leaves a bio-oil with lower nitrogen content in comparison with the original spent grains and low oxygen content. The viscosity profile of the spent grains indicated that activated alumina could promote liquefaction and prevent charring of the structure between 400 and 460 °C. The biochar contains about 10-12% of original carbon and 13-20% of starting nitrogen resulting very attractive as a soil amendment and for carbon sequestration. Overall, value can be added to the spent grains opening a new market in bio-fuel production without the needs of external energy. The bio-oil from spent grains could meet about 9% of the renewable obligation in the UK.

  5. 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...

  6. 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).

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Shabalin, M.; Fuks, D.

    2015-05-01

    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.

  9. Thermally activated step motion observed by HREM at a (113) symmetric tilt grain boundary in Al.

    SciTech Connect

    Merkle, K. L.; Thompson, L. J.; Phillipp, F.; Materials Science Division; Max-Planck-Inst.

    2002-11-01

    Grain-boundary migration is demonstrated to proceed by lateral propagation of a small step in a (113), [110] symmetric Al tilt grain-boundary. In-situ high-resolution (transmission) electron microscopy (HREM) at 523K allowed the study of atomic-scale detail at video rates during the migration process. The grain-boundary translational states on both sides of the step are identical, which leads to a step dislocation. This defect can move laterally by a combination of climb and glide. Dynamic HREM images indicate considerable atomic agitation within the dislocation core. A detailed temporal analysis of the step movements shows small random displacements of the dislocation core.

  10. 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

  11. Effect of a Compressive Uniaxial Strain on the Critical Current Density of Grain Boundaries in Superconducting YBa2Cu3O7-delta Films (POSTPRINT)

    DTIC Science & Technology

    2010-03-01

    composition by doping the grains [10] or the grain boundaries [11]. One of the most striking results is obtained by use of calcium doping in YBa2Cu3O7 (YBCO... Doping affects both the charge carrier concentra- tion and the strain fields at grain boundaries, which makes it hard to determine to what extent the...laser depo- sition onto single-crystal and bicrystalline SrTiO3 (STO) substrates. The bicrystalline substrates had symmetric [001]-tilt grain boundaries

  12. Platelet high-density lipoprotein activates transferrin-derived phagocytosis activators, MAPPs, following thrombin digestion.

    PubMed

    Sakamoto, Haruhiko; Wu, Bin; Nagai, Yumiko; Tanaka, Sumiko; Onodera, Masayuki; Ogawa, Takafumi; Ueno, Masaki

    2011-01-01

    Macromolecular activators of phagocytosis from platelets (MAPPs), transferrin-derived phagocytosis activators released from platelets, activate leukocytic phagocytosis via Fcγ receptors. It has been found that MAPPs can be prepared using stored platelets or their lysate. Using this artificial MAPP production system, it has been found that they can be produced from precursors (tetrameric and dimeric transferrins) following reaction with a low-molecular-weight (LMW) activator of MAPPs, which is liberated from a high-molecular-weight activator of MAPP (HMW activator) by reaction with thrombin. In this study, the HMW activator in platelet lysate was characterized by assaying phagocytosis of washed neutrophils. In an ultracentrifugation study of the platelet lysate, HMW activator activity was observed in the fraction corresponding to the density of high-density lipoprotein (HDL). The activity was observed in the apolipoproteins obtained from the HDL fraction. Among the apolipoproteins tested only apolipoprotein CIII showed the activity to produce MAPP in vitro. Affinity chromatography of the apolipoproteins from the HDL fraction of the platelet lysate using an anti-apolipoprotein CIII column revealed that the substance that binds with the antibody showed MAPP-forming activity. In a gel filtration study of thrombin-treated apolipoprotein CIII, a peak of LMW activator activity was observed for fractions with a molecular size smaller than that of apolipoprotein CIII. Finally, MAPP-forming activity of HDL obtained from the plasma was examined. MAPP was formed only when delipidized HDL was used. In conclusion, it is suggested that platelet HDL is the HMW activator and that this activation is achieved via apolipoprotein CIII after thrombin reaction in platelets.

  13. Active sensing: An innovative tool for evaluating grain yield and nitrogen use efficiency of multiple wheat genotypes

    NASA Astrophysics Data System (ADS)

    Naser, Mohammed Abdulridha

    Precision agricultural practices have significantly contributed to the improvement of crop productivity and profitability. Remote sensing based indices, such as Normalized Difference Vegetative Index (NDVI) have been used to obtain crop information. It is used to monitor crop development and to provide rapid and nondestructive estimates of plant biomass, nitrogen (N) content and grain yield. Remote sensing tools are helping improve nitrogen use efficiency (NUE) through nitrogen management and could also be useful for high NUE genotype selection. The objectives of this study were: (i) to determine if active sensor based NDVI readings can differentiate wheat genotypes, (ii) to determine if NDVI readings can be used to classify wheat genotypes into grain yield productivity classes, (iii) to identify and quantify the main sources of variation in NUE across wheat genotypes, and (iv) to determine if normalized difference vegetation index (NDVI) could characterize variability in NUE across wheat genotypes. This study was conducted in north eastern Colorado for two years, 2010 and 2011. The NDVI readings were taken weekly during the winter wheat growing season from March to late June, in 2010 and 2011 and NUE were calculated as partial factor productivity and as partial nitrogen balance at the end of the season. For objectives i and ii, the correlation between NDVI and grain yield was determined using Pearson's product-moment correlation coefficient (r) and linear regression analysis was used to explain the relationship between NDVI and grain yield. The K-means clustering algorithm was used to classify mean NDVI and mean grain yield into three classes. For objectives iii and iv, the parameters related to NUE were also calculated to measure their relative importance in genotypic variation of NUE and power regression analysis between NDVI and NUE was used to characterize the relationship between NDVI and NUE. The results indicate more consistent association between grain

  14. 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

  15. Antiaflatoxigenic property of food grade antioxidants under different conditions of water activity in peanut grains.

    PubMed

    Passone, María A; Resnik, Silvia; Etcheverry, Miriam G

    2007-08-15

    Analytical grade (AG) and industrial grade (IG) of three-food grade antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propyl paraben (PP) were analyzed to prove their fungitoxic effect on Aspergillus section Flavi strains. The effect of interactions among 10 antioxidant treatments at water activity levels (0.982, 0.955, 0.937 a(W)) for 11 and 35 days of incubation and at 25 degrees C in peanut grains on mycelial growth (CFU g(-1)) and aflatoxin B(1) (AFB(1)) accumulation were evaluated. Both antioxidant grade treatments had a significant effect (P<0.001) on fungal count. All antioxidant treatments showed the highest effectiveness on control of growth of peanut aflatoxigenic strains at 0.937 a(W) and at 11 days of incubation. Overall, AG and IG binary mixtures M3 (20+10 mM), M4 (20+20 mM) and ternary mixtures M5 (10+10+10 mM), M6 (10+20+10 mM), M7 (20+10+10 mM) and M8 (20+20+10 mM) were the treatments most effective at inhibiting growth of Aspergillus section Flavi strains. Industrial grade BHA 10 and 20 mM, binary mixtures M1 (10+10 mM), M2 (10+20 mM), M3 (20+10 mM), M4 (20+20 mM) and ternary mixtures M5 (10+10+10 mM), M6 (10+20+10 mM), M7 (20+10+10 mM) and M8 (20+20+10 mM) completely inhibited AFB(1) production. The studied results suggest that IG antioxidant mixtures have potential for controlling growth of these mycotoxigenic species and prevent aflatoxin accumulation at the peanut storage system.

  16. Aromatic plants essential oils activity on Fusarium verticillioides Fumonisin B(1) production in corn grain.

    PubMed

    López, A G; Theumer, M G; Zygadlo, J A; Rubinstein, H R

    2004-10-01

    The minimum inhibitory concentration (MIC) of Origanum vulgare, Aloysia triphylla, Aloysia polystachya and Mentha piperita essential oils (EOs) against Fusarium verticillioides M 7075 (F. moniliforme, Sheldon) were assessed, using the semisolid agar antifungal susceptibility (SAAS) technique. O. vulgare, A. triphylla, A. polystachya and M. piperita EOs were evaluated at final concentrations of 10, 20, 40, 50, 100, 200, 250, 500, 1000 and 1500 epsilonl per litre (epsilonl/l) of culture medium. A. triphylla and O. vulgare EOs showed the highest inhibitory effects on F. verticillioides mycelial development. This inhibition was observed at 250 and 500 epsilonl/l for EOs coming from Aloysia triphylla and O. vulgare, respectively. Thus, the effects of EOs on FB(1) production were evaluated using corn grain (Zea mays) as substrate. The EOs were inserted on the 5th, 10th, 15th and 20th day of maize postinoculation with a conidia suspension of F. verticillioides. O. vulgare and A. triphylla were applied to give final concentrations of 30 ppm and 45 ppm, respectively. Different effects were observed in the toxicogenicity at the 20th day treatment. The O. vulgare EO decreased the production level of FB(1) (P < 0.01) while A. triphyla EO increased it (P < 0.001) with respect to those obtained in the inoculated maize, not EOs treated. Results obtained in the present work indicate that fumonisin production could be inhibited or stimulated by some constituents of EOs coming from aromatic plants. Further studies should be performed to identify the components of EOs with modulatory activity on the growth and fumonisins production of Fusarium verticillioides.

  17. Coarse-grained time-dependent density functional simulation of charge transfer in complex systems: application to hole transfer in DNA.

    PubMed

    Kubar, Tomás; Elstner, Marcus

    2010-09-02

    We present a coarse-grained tight-binding method based on density functional theory (DFT) for the simulation of charge transfer in complex materials. The charge-transfer parameters are computed using a fragment-orbital approach combined with the approximative DFT method self-consistent charge density functional tight binding (SCC-DFTB), which allows to follow the dynamics of excess charge along nanosecond MD trajectories, still accounting for the important impact of structural fluctuations and solvent effects. Since DFT suffers from the self-interaction error, which would lead to a delocalization of the hole charge over the entire system, we study the effect of an empirical self-interaction correction in detail. The wave function of the excess charge is propagated within the framework of time-dependent DFT, where the electron (hole) and the atomic system are propagated simultaneously according to the derived coupled equations of motion. In the case of DNA, the solvent polarization effects are a dominant factor affecting the hole transport. The hole charge polarizes the surrounding water, which in turn supports a localization of the hole charge--a water polaron is formed, extended dynamically over several nucleobases. As this polarization of water accompanies the migrating hole, the motion of hole is significantly slowed down due to the solvent reorganization energy involved. The estimated hopping rate between neighboring adenines in poly(A)-DNA is in the order of 100 ns(-1), and our simulations clearly show that the charge transfer occurs in a nonadiabatic fashion, due to the small average electronic coupling of around 0.06 eV.

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

    PubMed

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

    2014-06-01

    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.

  19. Improved critical current density in ex situ processed MgB2 tapes by the size reduction of grains and crystallites by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Fujii, Hiroki; Ishitoya, Akira; Itoh, Shinji; Ozawa, Kiyoshi; Kitaguchi, Hitoshi

    2017-03-01

    We have fabricated Fe-sheathed MgB2 tapes through an ex situ process in a powder-in-tube (PIT) technique using powders ball milled under various conditions. Although the ex situ processed wires and tapes using the high-energy ball milled MgB2 powders have been studied and the decrease of grain and crystallite sizes of MgB2 and the critical current density (Jc) improvement of those conductors were reported so far, the use of filling powders milled at a higher rotation speed than previously reported further decreases the crystallite size and improves the Jc properties. The improved Jc values at 4.2 K and 10 T were nearly twice as large as those previously reported. Those milled powders and hence as-rolled tapes easily receive contamination in air. Thus, the transport Jc properties are easily deteriorated and scattered unless the samples are handled with care. The optimized heat treatment temperature (Topt) of those tape samples at which best performance in the Jc property is obtained decreases by more than 100 °C, compared with that of tapes using the as-received MgB2 powder.

  20. 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

  1. Active removal of orbital debris by induced hypervelocity impact of injected dust grains

    NASA Astrophysics Data System (ADS)

    Ganguli, G.; Crabtree, C.; Velikovich, A.; Rudakov, L.; Chappie, S.

    2014-02-01

    Collisions of an active satellite with a small (1mm - cm) untrackable orbital debris can be mission ending. It has been recently established that we are at the tipping point for collisional cascade of larger objects to exponential growth of small orbital debris. This will make access to near-Earth space hazardous without first clearing the existing debris from this region. We present a concept for elimination of small debris by deploying micron scale dust to artificially enhance the drag on the debris. The key physics that makes this technique viable is the possibility of large momentum boost realized through hypervelocity dust/debris collision. By deploying high mass density micron scale dust in a narrow altitude band temporarily it is possible to artificially enhance drag on debris spread over a very large volume and force rapid reentry. The injected dust will also reenter the atmosphere leaving no permanent residue in space.

  2. Diffusion length and grain boundary recombination activity determination by means of induced current methods

    NASA Astrophysics Data System (ADS)

    Shabelnikova, Yana; Yakimov, Eugene

    2016-11-01

    The application of induced current methods for a quantitative description of multicrystalline silicon solar cell properties is demonstrated. For the minority carriers' diffusion length (L) and grain boundary recombination velocity (Vs) determination three types of measurements were used. They included the measurement of EBIC signal dependence on electron beam energy and of EBIC and XBIC grain boundary contrast profiles. The L and Vs values obtained by means of minimization the residual function between measured and model induced current curves are presented. The inaccuracy of obtained parameters is discussed for each of three types of measurements.

  3. Biological activity of ethanolic extract fractions of Dracaena arborea against infestation of stored grains by two storage insect pests.

    PubMed

    Epidi, T T; Udo, I O

    2009-07-01

    As part of on-going efforts to use eco-friendly alternatives to chemical pesticides, ethanolic extract of dried leaves of Dracaena arborea (Willd.) Link (Dragon tree; Dracaenaceae) dissolved in distilled water and partitioned between equal volumes of n-hexane, chloroform, ethyl acetate and butanol was assessed in the laboratory against infestation by Sitophillus zeamais Motsch. and Callosobruchus maculatus Walp. in stored maize and cowpea, respectively. One hundred grams each of maize grains and cowpea seeds were treated with 400 mg kg(-1) of each extract fraction to evaluate contact toxicity, damage assessment, effect on eggs and immature stages and progeny production in both insect species. Contact toxicity by topical application, toxicity upon filter paper application and repellency using area preference method were carried out on the two insect species. Results showed that the extract fraction caused significant (p < or = 0.05) mortality of both insect pests with a high residual contact activity against S. zeamais. Grain damage was significantly (p < or = 0.01) reduced, while progeny production and development of eggs within grains were inhibited. The extract fractions evoked a strong repellent action against S. zeamais but moderate action against C. maculatus. The full potentials of using extract fractions of D. arborea as grain protectant against infestation by insect pests is discussed.

  4. Dust grains in the coma of 67P/Churyumov-Gerasimenko - link with surface properties and cometary activity

    NASA Astrophysics Data System (ADS)

    Capria, M. T.; Ivanovski, S.; Zakharov, W.; Capaccioni, F.; Filacchione, G.; De Sanctis, M. C.; Rotundi, A.; Della Corte, V.; Longobardo, A.; Palomba, E.; Colangeli, L.; Bockelee-Morvan, D.; Erard, S.; Leyrat, C.

    2016-11-01

    The imaging spectrometer VIRTIS and the dust analyzer GIADA, onboard Rosetta, made an extensive observation of the dust particles in the coma of the comet 67P/Churyumov-Gerasimenko. From the analysis of GIADA data, two different kind of particles have been revealed, compact and fluffy with different compositions and dynamical properties. Compact particles are characterized by densities of about 10E3 kg/m3, while fluffy particles have an almost fractal nature, with densities less than 1 kg/m3. In this work we present the initial results of a model linking the dust flux distribution, as obtained from a theoretical thermal nucleus model, with a model describing the dynamics of aspherical grains in the coma. The results are discussed in the context of the latest observations from VIRTIS and GIADA instruments. The 2D nucleus thermal model, when applied to the real shape of the comet, provides the size distribution and physical properties of the emitted grains at different times and location on the surface. The thermal model can simulate grains of various size distribution, composition and physical properties. This information is used as an input for the dust dynamical model that follows the emitted particles in the coma. The main source of heating is the solar illumination. In the dust dynamical model, the grain trajectory of emitted particles remains in a plane perpendicular to the rotational axis and the direction of illumination is taken to be in the same plane (i.e. does not cause transversal forces). The dust particles are assumed to be isothermal convex bodies and temperature changes only induce modest changes in the aerodynamic force (twice higher temperature changes aerodynamic force less than 30%). This study reviews the theoretical values at which temperature difference starts to play a role on the dynamics. We discuss to what extent the particle's temperature affects the terminal velocities of the dust grains in the 67P coma in dependence on their mass and

  5. 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.

  6. Effect of a Compressive Uniaxial Strain on the Critical Current Density of Grain Boundaries in Superconducting YBa2Cu3O7-delta Films

    DTIC Science & Technology

    2009-07-09

    the chemical composition by doping the grains [10] or the grain boundaries [11]. One of the most striking results is obtained by use of calcium doping ...increase in Jc;GB [12–14]. Doping affects both the charge carrier concentra- tion and the strain fields at grain boundaries, which makes it hard to...deposited by pulsed-laser depo- sition onto single-crystal and bicrystalline SrTiO3 (STO) substrates. The bicrystalline substrates had symmetric [001

  7. 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)

  8. 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.

  9. Facies architecture of submarine channel deposits on the western Niger Delta slope: Implications for grain-size and density stratification in turbidity currents

    NASA Astrophysics Data System (ADS)

    Jobe, Zane; Sylvester, Zoltán.; Pittaluga, Michele Bolla; Frascati, Alessandro; Pirmez, Carlos; Minisini, Daniel; Howes, Nick; Cantelli, Alessandro

    2017-02-01

    High-resolution bathymetry, seismic reflection, and piston core data from a submarine channel on the western Niger Delta slope demonstrate that thick, coarse-grained, amalgamated sands in the channel thalweg/axis transition to thin, fine-grained, bedded sands and muds in the channel margin. Radiocarbon ages indicate that axis and margin deposits are coeval. Core data show that bed thickness, grain size, and deposition rate strongly decrease with increasing height above channel thalweg and/or distance from channel centerline. A 5 times decrease in bed thickness and 1-2 ψ decrease in grain size are evident over a 20 m elevation change (approximately the elevation difference between axis and margin). A simplified in-channel sedimentation model that solves vertical concentration and velocity profiles of turbidity currents accurately reproduces the vertical trends in grain size and bed thickness shown in the core data set. The close match between data and model suggests that the vertical distribution of grain size and bed thickness shown in this study is widely applicable and can be used to predict grain size and facies variation in data-poor areas (e.g., subsurface cores). This study emphasizes that facies models for submarine channel deposits should recognize that grain-size and thickness trends within contemporaneous axis-margin packages require a change in elevation above the thalweg. The transition from thick-bedded, amalgamated, coarser-grained sands to thin-bedded, nonamalgamated, finer-grained successions is primarily a reflection of a change in elevation. Even a relatively small elevation change (e.g., 1 m) is enough to result in a significant change in grain size, bed thickness, and facies.

  10. Certain Grain Foods Can Be Meaningful Contributors to Nutrient Density in the Diets of U.S. Children and Adolescents: Data from the National Health and Nutrition Examination Survey, 2009–2012

    PubMed Central

    Papanikolaou, Yanni; Fulgoni, Victor L.

    2017-01-01

    Grain foods may play an important role in delivering nutrients to the diet of children and adolescents. The present study determined grain food sources of energy/nutrients in U.S. children and adolescents using data from the National Health and Nutrition Examination Survey, 2009–2012. Analyses of grain food sources were conducted using a 24-h recall in participants 2–18 years old (N = 6109). Sources of nutrients contained in grain foods were determined using U.S. Department of Agriculture nutrient composition databases and excluded mixed dishes. Mean energy and nutrient intakes from the total diet and from various grain foods were adjusted for the sample design using appropriate weights. All grains provided 14% ± 0.2% kcal/day (263 ± 5 kcal/day), 22.5% ± 0.3% (3 ± 0.1 g/day) dietary fiber, 39.3% ± 0.5% (238 ± 7 dietary folate equivalents (DFE)/day) folate and 34.9% ± 0.5% (5.6 ± 0.1 mg/day) iron in the total diet in children and adolescents. The current analyses showed that certain grain foods, in particular breads, rolls and tortillas, ready-to-eat cereals and quick breads and bread products, are meaningful contributors of folate, iron, thiamin, niacin and dietary fiber, a nutrient of public health concern as outlined by the 2015–2020 Dietary Guidelines for Americans. Thus, specific grain foods contribute to nutrient density and have the potential to increase the consumption of several under-consumed nutrients in children and adolescents. PMID:28230731

  11. Optimization of processing conditions to improve antioxidant activities of apple juice and whey based novel beverage fermented by kefir grains.

    PubMed

    Sabokbar, Nayereh; Khodaiyan, Faramarz; Moosavi-Nasab, Marzieh

    2015-06-01

    A central composite design (CCD) was used to evaluate the effects of fermentation temperature (20-30 ºC) and kefir grains amount (2-8%w/v) on total phenolic content and antioxidant activities of apple juice and whey based novel beverage fermented by kefir grains. The response surface methodology (RSM) showed that the significant second-order polynomial regression equation with high R(2) (>0.86) was successfully fitted for all response as function of independent variable. The overall optimum region was found to be at the combined level of 7.56%w/v kefir grains and temperature of 24.82 ºC with the highest value for total phenolic content (TPC) and antioxidant activities. At this optimum point TPC, 1, 1-Diphenyl-2-picrylhydrazyl radical scavenging, metal chelating effect, reducing power, inhibition of linoleic acid autoxidation and inhibition of ascorbate autoxidation were 165.02 mgGA/l, 0.38 ml/1 ml, 0.757 (absorbance at 700 nm), 46.12 %, 65.33 % and 21 %, respectively. No significant difference (p < 0.05) was found between actual values and predicated values.

  12. 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…

  13. 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.

  14. Stochastic modeling of grain-fabric formation

    NASA Astrophysics Data System (ADS)

    Naruse, H.

    2011-12-01

    In this study, we developed a stochastic model of the grain-fabric formation, and performed flume experiments and field observations to examine the model predictions. It has been suggested that the grain fabric (preferred orientation of grain long axes) of sand/sandstone provides significant sedimentological information such as paleocurrent direction, sediment-transport processes, and depositional environments . Grains orient along preferred directions because of interactions between fluids and sediment particles , and it has been known that there are two types of preferred grain orientations-a(p)a(i) and a(t)b(i). a(t)b(i)- and a(p)a(i)-type fabrics are preferred grain orientations that are perpendicular and parallel to the flow direction, respectively. River gravels tend to exhibit the a(t)b(i) fabric, whereas turbidite sandstones often exhibit the a(p)a(i) fabric; nonetheless, there exist many exceptions, and the grain-fabric tendency often fluctuates even in a single bed. The cause of the two types of grain fabric currently unknown, and the flow parameters that influence the fabric type have not yet been determined . Toward this end, we developed a stochastic model of grain-fabric formation that consider probabilistic density functions (PDFs) of the orientations of both influx and outflux grains to an active layer of surface sediments. Flume experiments using rice grains provided the PDFs of both influx and outflux grain orientation that can be well approximated by the von Mises distribution. On average, the orientations of influx and outflux grains were both perpendicular to the flow direction. This is because the projection area of a grain to the flow direction is maximized when the grain orients perpendicular to the flow. The proposed model predicts that larger grains or weaker flow (low Shields dimensionless stress) produces the a(t)b(i) fabric whereas an intense flow (high Shields dimensionless stress) produces the a(p)a(i) fabric. It also predicts that

  15. Copper indium gallium (di)selenide: Electronic activities of grain boundaries and solar cell fabrication studies

    NASA Astrophysics Data System (ADS)

    Erkan, Mehmet Eray

    This dissertation is composed of three studies related to chalcopyrite solar cells. The first study is on electronic activities of grain boundaries (GBs) in CuInSe2 (CIS). Despite being polycrystalline, chalcopyrite thin film solar cells have reached record power conversion efficiencies. This is against the classical understanding on the effect of GBs in semiconductor materials. Because GBs are expected to be recombination centers and barriers against the carrier flow, reducing the device efficiency. Therefore, a complete understanding on the electronic behavior of chalcopyrite GBs is missing. Moreover, the high efficiency chalcopyrite solar cells are grown with Na impurities which positively affect the performance of the solar cell, so-called sodium effect. Research on chalcopyrite GBs has been coupled with the effect of Na impurities, because Na has been found segregated at the GBs. The study presented in this dissertation was performed on GBs in a Na-free CIS. It is important to study the GBs in a Na-free chalcopyrite to avoid any uncontrolled effects of Na segregation at the GBs, for instance a possible Na-related secondary phase formation which would affect the conclusions drawn on the natural behavior of chalcopyrite GBs. In addition, it is known that Sigma3 GBs in chalcopyrite solar cells are abundant; therefore, it is meaningful to investigate the differences between Sigma3 and non-Sigma3 GBs. For this purpose, Sigma3, close to Sigma3 and Sigma9 GBs in a Bridgman-grown multicrystalline Na-free CIS wafer were identified by electron backscatter diffraction and their electronic properties were investigated by Kelvin probe force microscope and cathodoluminescence in scanning electron microscope. It is shown that the Sigma3 GB is neutral and it does not behave as a recombination center, whereas once the geometry of a GB deviates from the Sigma3 geometry, such as close to Sigma3 and Sigma9 GBs, the GB becomes charged and behaves as a recombination center. This

  16. Self-Polarizing Microswimmers in Active Density Waves

    NASA Astrophysics Data System (ADS)

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio

    2017-02-01

    An artificial microswimmer drifts in response to spatio-temporal modulations of an activating suspension medium. We consider two competing mechanisms capable of influencing its tactic response: angular fluctuations, which help it explore its surroundings and thus diffuse faster toward more active regions, and self-polarization, a mechanism inherent to self-propulsion, which tends to orient the swimmer’s velocity parallel or antiparallel to the local activation gradients. We investigate, both numerically and analytically, the combined action of such two mechanisms. By determining their relative magnitude, we characterize the selective transport of artificial microswimmers in inhomogeneous activating media.

  17. Self-Polarizing Microswimmers in Active Density Waves.

    PubMed

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio

    2017-02-09

    An artificial microswimmer drifts in response to spatio-temporal modulations of an activating suspension medium. We consider two competing mechanisms capable of influencing its tactic response: angular fluctuations, which help it explore its surroundings and thus diffuse faster toward more active regions, and self-polarization, a mechanism inherent to self-propulsion, which tends to orient the swimmer's velocity parallel or antiparallel to the local activation gradients. We investigate, both numerically and analytically, the combined action of such two mechanisms. By determining their relative magnitude, we characterize the selective transport of artificial microswimmers in inhomogeneous activating media.

  18. Self-Polarizing Microswimmers in Active Density Waves

    PubMed Central

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio

    2017-01-01

    An artificial microswimmer drifts in response to spatio-temporal modulations of an activating suspension medium. We consider two competing mechanisms capable of influencing its tactic response: angular fluctuations, which help it explore its surroundings and thus diffuse faster toward more active regions, and self-polarization, a mechanism inherent to self-propulsion, which tends to orient the swimmer’s velocity parallel or antiparallel to the local activation gradients. We investigate, both numerically and analytically, the combined action of such two mechanisms. By determining their relative magnitude, we characterize the selective transport of artificial microswimmers in inhomogeneous activating media. PMID:28181504

  19. No Evidence for Activity Adjustment in Response to Increased Density in Daphnia magna

    PubMed Central

    Sereni, Laura; Einum, Sigurd

    2015-01-01

    Increased population density may lead to a decrease in energy available for growth and reproduction via effects on the activity level of individuals. Whilst this may be of particular importance for organisms that compete for defendable resources and/or have a high frequency of social interactions, it is less obvious how individual activity should covary with population density when food resources are not defendable or direct interactions among individuals are negligible. Based on observations that there is a general negative relationship between population density and metabolism it has been suggested that organisms actively reduce activity under increased density to accommodate an expected decrease in food availability. However, in the absence of direct activity measurements the validity of this hypothesis is unclear. Here we test for such anticipatory adjustments of activity levels in the planktonic cladoceran Daphnia magna Straus, a filter feeder whose food resources are not defendable, meaning that density responses can be evaluated in the absence of direct interactions. We tested for changes in activity in response to two separate density cues, one being the direct physical and visual stimuli resulting from being in the vicinity of conspecifics (‘direct density experiment’), and the other being the detection of olfactory cues in their environment (‘olfactory cue experiment’). Ten genetically distinct clones were used to evaluate the potential for genetic variation in these responses. Our measures of activity were highly repeatable, and there was significant variation in activity among clones. Furthermore, this clonal variation was consistent in the ‘direct density’ and ‘olfactory cue’ experiments. The estimated evolvability of the trait (1.3–3.2%) was within the range typically observed in behavioural traits. However, there was no indication that the activity level of individuals respond to population density, either directly to actual density

  20. 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.

  1. Prospects for Improving the Critical Current Density of Superconducting Nb3Sn Strands via Optimization of Nb3Sn Fraction, Stoichiometry, and Grain Size

    NASA Astrophysics Data System (ADS)

    Xu, Xingchen

    Superconducting Nb3Sn strands are the key building blocks of high-field (>10 T) magnets. There are multiple figures of merit defining the quality of a Nb3Sn strand, such as critical current density (Jc), residual resistivity ratio (RRR), and effective subelement size (deff). Among these the high-field Jc is the key factor for the application of Nb3Sn strands in magnets, because the supercurrent-carrying capability of Nb 3Sn strands essentially determines the limit of the magnetic field that can be generated in a given magnet design. It is the primary goal of this dissertation to explore ways to improve the high-field non-matrix Jc of Nb3Sn strands without sacrificing other factors (e.g., RRR and deff). A green-state Nb3Sn wire is composed of precursor metals or alloys, which transform to superconducting Nb3Sn phase through a diffusion reaction process during a heat treatment at typically 600-800 °C. The high-field non-matrix Jc of Nb 3Sn strands was improved significantly due to the extensive efforts by the scientists of the Nb3Sn community. These improvements in Jc were mainly driven by three aspects: improvement of the subelement design (i.e., optimizing the subelement architecture and the precursor amounts, e.g., enhancing the Nb and Sn fractions in subelements), use of the right type and amount of dopants, and optimization of the heat treatment schedules. However, the improvement in Jc of Nb3Sn strands has plateaued since 2002, with the rod-restack-process (RRP) strands pushing the 4.2 K, 12 T non-matrix Jc to ˜3000 A/mm2, and the 15 T value to ˜1600 A/mm 2. Given the plateau of Jc improvement over the last decade, researchers have been asking this question: how to further improve the high-field Jc of Nb3Sn strands? This is also the question that this dissertation aims to answer. For this goal, a literature review of the factors determining non-Cu Jc of Nb3Sn conductors is given in chapter 1. It is seen that the non-matrix Jc of Nb 3Sn strands are mainly

  2. 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.

  3. Can phosphatidylserine enhance atheroprotective activities of high-density lipoprotein?

    PubMed

    Darabi, Maryam; Kontush, Anatol

    2016-01-01

    Although high-density lipoprotein (HDL) is well known to be protective against atherosclerotic cardiovascular disease, therapeutic interventions to raise HDL-cholesterol levels do not translate into reduction in cardiovascular risk. Due to the compositional complexity of HDL particles, molecular determinants of their atheroprotective function still remain to be clarified. Recent structural and functional data identify phospholipid as a major bioactive component of HDL. Such a role has recently been specifically evidenced for phosphatidylserine (PS); indeed, HDL content of PS displayed positive correlations with all metrics of HDL functionality assessed. This review summarizes current knowledge about HDL-associated PS; possible mechanisms for its atheroprotective role are discussed and potential applications of PS to HDL-based therapies are highlighted.

  4. 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

  5. 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

  6. Grain fever syndrome induced by inhalation of airborne grain dust.

    PubMed

    doPico, G A; Flaherty, D; Bhansali, P; Chavaje, N

    1982-05-01

    To study the clinical and physiologic manifestations of the grain fever syndrome and the potentially pathogenic role of complement activation, 12 subjects (six grain workers and six healthy non-grain workers) underwent inhalation provocations with airborne grain dust. The clinical response was characterized by facial warmth, headache, malaise, myalgias, feverish sensation, chilliness, throat and tracheal burning sensation, chest tightness, dyspnea, cough, and expectoration. Fever developed in four grain workers and two controls. Leukocytosis, ranging between 11,700 and 24,300 leukocytes/mm3 with left shift, developed in five grain workers and five controls. There was no evidence of complement activation by the classical or alternate pathway. None of the subjects had serum precipitins to grain dust. The pulmonary response was characterized by a decrease in FEV1, FVC, MMF, Vmax50, and Vmax75, with significant rise in pulmonary resistance and consistent change in dynamic compliance but without changes in static compliance or diffusing capacity. Hence, grain dust inhalation induced diffuse airways obstruction without detectable parenchymal reaction. The airways response to high concentrations of grain dust inhalation were unrelated to the presence of immediate skin hypersensitivity. Although we cannot exclude the etiopathogenetic role of an immunologic reaction to grain dust, our data do not support the hypothesis that the grain fever syndrome is a precipitin-mediated allergic pneumonitis. More likely, the manifestations of grain fever probably reflect the host reaction to grain dust bacterial endotoxins and/or nonallergic mediator release by grain or grain dust constituents.

  7. Temperature and density structure of a recurring active region jet

    NASA Astrophysics Data System (ADS)

    Mulay, Sargam M.; Zanna, Giulio Del; Mason, Helen

    2017-01-01

    Aims: We present a study of a recurring jet observed on October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on board the Solar Dynamic Observatory, the X-ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the physical parameters of the jet that are obtained using imaging and spectroscopic observations, such as density, differential emission measure, peak temperature, velocity, and filling factor. Methods: A differential emission measure (DEM) analysis was performed at the region of the jet spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The resulting EIS DEM curves were compared to those obtained with AIA-XRT. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The predicted total count rates for each AIA channel were compared with the observed count rates. The effects of varying elemental abundances and the temperature range for the DEM inversion were investigated. Spectroscopic diagnostics were used to obtain an electron number density distribution for the jet spire and the jet footpoint. Results: The plasma along the line of sight in the jet spire and jet footpoint was found to be peak at 2.0 MK (log T [K] = 6.3). We calculated electron densities using the Fe XII (λ186/λ195) line ratio in the region of the spire (Ne = 7.6 × 1010 cm-3) and the footpoint (1.1 × 1011 cm-3). The plane-of-sky velocity of the jet is found to be 524 km s-1. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. The synthetic spectra contributing to each AIA channel confirms the multi-thermal nature of the AIA channels in both regions. There is no indication of high temperatures, such as emission from Fe XVII (λ254.87) (log T [K] = 6.75) seen in the jet spire. In the case of the jet footpoint, synthetic spectra predict weak contributions from Ca XVII (λ192.85) and Fe XVII (λ254.87). With further investigation, we confirmed

  8. 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.

  9. Cupressaceae pollen grains modulate dendritic cell response and exhibit IgE-inducing adjuvant activity in vivo.

    PubMed

    Kamijo, Seiji; Takai, Toshiro; Kuhara, Takatoshi; Tokura, Tomoko; Ushio, Hiroko; Ota, Mikiko; Harada, Norihiro; Ogawa, Hideoki; Okumura, Ko

    2009-11-15

    Pollen is considered a source of not only allergens but also immunomodulatory substances, which could play crucial roles in sensitization and/or the exacerbation of allergies. We investigated how allergenic pollens from different plant species (Japanese cedar and Japanese cypress, which belong to the Cupressaceae family, and birch, ragweed, and grass) modulate murine bone marrow-derived dendritic cell (DC) responses and examined the effect of Cupressaceae pollen in vivo using mice. DCs were stimulated with pollen extracts or grains in the presence or absence of LPS. Cell maturation and cytokine production in DCs were analyzed by flow cytometry, ELISA, and/or quantitative PCR. Pollen extracts suppressed LPS-induced IL-12 production and the effect was greatest for birch and grass. Without LPS, pollen grains induced DC maturation and cytokine production without IL-12 secretion and the response, for which TLR 4 was dispensable, was greatest for the Cupressaceae family. Intranasal administration of Cupressaceae pollen in mice induced an elevation of serum IgE levels and airway eosinophil infiltration. Coadministration of ovalbumin with Cupressaceae pollen grains induced ovalbumin-specific IgE responses associated with eosinophil infiltration. The results suggest that modulation of DC responses by pollen differs among the plant families via (1) the promotion of DC maturation and cytokine production by direct contact and/or (2) the inhibition of IL-12 production by soluble factors. The strong DC stimulatory activity in vitro and IgE-inducing activity in mice support the clinical relevance of Cupressaceae pollen to allergies in humans.

  10. 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.

  11. Preliminary Results of Activated Sintering Mechanism and Grain Boundary Prewetting/premelting in Nickel-doped Tungsten

    SciTech Connect

    Gupta, V K; Yoon, D H; Luo, Jian; Meyer III, Harry M

    2005-01-01

    Supported by prior lattice-gas and phase-field simulations, we proposed that nanoscale intergranular and surficial amorphous films in multicomponent ceramic materials can be treated as a case of combined interfacial prewetting and premelting. Consequently, a class of parallel interfacial phenomena, i.e., coupled interfacial adsorption and disordering, is anticipated to occur in multicomponent metallic alloys. An exploratory study was carried out wherein grain boundary segregation in a model binary metallic alloy (Ni-doped W) was characterized as a function of temperature and dopant concentration. Doped specimens were prepared using high purity chemicals, sintered in flowing H2/N2 mixture, and examined using Auger spectroscopy and electron microscopy. Preliminary results are presented and discussed with respect to a prewetting/premelting model versus the classical Langmuir-McLean and BET models. An additional goal of this study is to resolve the long-standing mystery of solid-state activated sintering mechanism for nickel-doped tungsten. Use of ultra-pure materials confirmed the occurrence of nickel activated sintering of tungsten in the solid-state. We demonstrated that, contrary to the previous belief, Ni-rich secondary bulk phase does not penetrate along GBs and the solid-state activator should be a nanoscale interfacial phase that does not appear in the bulk phase diagram. The solid-state activated sintering in the model metallic system of Ni-doped W is therefore attributed to the enhance diffusion in a coupled grain boundary disordering and adsorption region, analogous to activated sintering via accelerated mass transport in nanoscale intergranular and surficial amorphous film in the model oxide system of Bi2O3-doped ZnO.

  12. On the relationship between grain-boundary migration and grain-boundary diffusion by molecular-dynamics simulation

    SciTech Connect

    Schoenfelder, B. |; Keblinski, P.; Wolf, D.; Phillpot, S.R.

    1998-07-01

    A molecular-dynamics method for the simulation of the intrinsic migration behavior of individual, flat grain boundaries is presented. A constant driving force for grain-boundary migration is generated by imposing an anisotropic elastic strain on a bicrystal such that the elastic-energy densities in its two halves are different. For the model case of the large-planar-unit-cell, high-angle (001) twist boundary in Cu the authors demonstrate that the drift velocity is proportional to the applied driving force, thus enabling determination of the boundary mobility. The activation energy for grain-boundary migration is found to be distinctly lower than that for grain-boundary self-diffusion. A decrease in the related activation energies with increasing temperature is shown to arise from a crossover in the underlying mechanisms, from solid-like at low temperatures to liquid-like at high-temperatures that is accompanied by an underlying grain-boundary structural transition.

  13. [Diurnal biting activity and seasonal density of Lutzomyia (C) orestes (Diptera: Psychodidae)].

    PubMed

    Lugo Mendoza, J; Aldecoa Gilí, T; Miqueli Negrín, E; Luis Pelegrino, J

    1991-01-01

    Daily bite activity and season density of Lutzomyia (C) orestes were recorded by means of the human bait technique in the Don Martin Cave, west of Havana Province, during one year. A correlation matrix test was carried out between density, temperature, relative humidity and rainfall.

  14. 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

  15. [Tannins, phytic phosphorus, phytase activity in the seed of 12 sorghum grain hybrids (Sorghum bicolor (L) Moench)].

    PubMed

    Ojeda, Alvaro; Frías, Amarayma; González, Rafael; Linares, Zoraida; Pizzani, Pablo

    2010-03-01

    In order to evaluate the variability in concentration of secondary metabolites among grains from different sorghum hybrids (Sorghum bicolor (L) Moench) and provide some information for rational use in animal feeds, grain samples were collected from 12 hybrids (Criollo 1, Criollo 27, Chaguaramas III, Chaguaramas VII, Cristiani Burkard H-8046-2, Guanipa 95, Himeca 101, Himeca 400, Pioneer 81-G67, Pioneer 83-G88, Pioneer 86-P42 y Tecsem 120) sowed on 2008 in the Turén municipality, Portuguesa State-Venezuela. Using standardized analytical methods, hybrids showed polyphenolics compounds contents (0.92 +/- 0.37% TaE), total (0.61 +/- 0.29% TaE) and condensed tannins (0.95 +/- 0.65% LeuE), phytic phosphorus (0.17 +/- 0.03%) and intrinsic phytase activity (12.3 +/- 6.74 U/kg) in the ranges described in the literature, with an important variation among hybrids that must be considered for their inclusion levels in the formulation of balanced feeds, as well as plant breeding programs.

  16. 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

  17. Multiday thermospheric density oscillations associated with variations in solar radiation and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Xu, Jiyao; Wang, Wenbin; Zhang, Shunrong; Liu, Xiao; Yuan, Wei

    2015-05-01

    Thermospheric densities observed by Challenging Minisatellite Payload and Gravity Recovery and Climate Experiment satellites during 2002-2010 and the globally averaged thermospheric densities from 1967 to 2007 have been used to investigate latitudinal, longitudinal, and height dependences of the multiday oscillations of thermospheric densities. The data show that the main multiday oscillations in thermospheric densities are 27, 13.5, 9, and 7 day oscillations. The high-correlation coefficients between the density oscillations and the F10.7 or Ap index indicate that these oscillations are externally driven. The 27 day density oscillation, being the strongest, is induced by variations in solar radiation, as well as recurrent geomagnetic activity that is the result of corotating interaction regions (CIRs) and high-speed solar wind streams of coronal hole origin. Density oscillations at periods of 13.5, 9, and 7 days at solar minimum and during the declining phase are stronger than those at solar maximum. These oscillations are mainly associated with recurrent geomagnetic activity due to coronal hole high-speed streams and CIRs. The multiday, periodic oscillations of thermospheric density exhibit strong latitudinal and longitudinal variations in the geomagnetic coordinate and oscillate synchronously at different heights. Oscillations with zonal wave number 0 oscillate globally, whereas those with nonzero wave numbers are strong at high geomagnetic latitudes, and hemispherically asymmetric. They are stronger in the Southern Hemisphere. The spectral distributions of thermospheric densities at different heights have almost the same latitude and longitude structures, but the spectral magnitudes increase with height.

  18. Insecticidal activity of the root extract of Decalepis hamiltonii against stored-product insect pests and its application in grain protection.

    PubMed

    Rajashekar, Y; Gunasekaran, N; Shivanandappa, T

    2010-06-01

    Root extracts of Decalepis hamiltonii were tested for insecticidal activity against the stored products pests, Rhyzopertha domonica, Sitophilus oryzae, Stigobium pancieum, Tribolium castaneum and Callosobruchus chinensis, in residual and contact toxicity bioassays. Methanolic extract showed LC50 value of 0.14 mg/cm(2) for all the test species in a filter paper residual bioassay. The extract was effective as a grain protectant for wheat and green gram. Reduction of F1 progeny was observed in treated grain stored for 3-4 months. The extract did not affect the germination of the treated grains. Our results indicate that methanolic extracts of D. hamiltonii has a potential to control stored product pests and could serve as a natural grain protectant.

  19. 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.

  20. 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

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

    PubMed

    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.

  2. 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

  3. 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.

  4. Effects of zinc on CarE activities and its gene transcript level in the English grain aphid, Sitobion avenae.

    PubMed

    Gao, Huan-Huan; Zhao, Hui-Yan; Yang, Jie; Zhang, Li; Bai, Xiao-Hui; Hu, Zu-Qing; Hu, Xiang-Shun

    2014-05-15

    As a selective stress, heavy metals play an important role in inducing the adaptive adjustments of insects to changing environments. Carboxylesterase (CarE) is one kind of biomarker that could help us to explore the adaptation mechanism of aphids to heavy metal stress. In this study, CarE activity and gene expression level were investigated in English grain aphids, Sitobion avenae (F.) (Hemiptera: Aphididae), exposed to Zn2+ at concentrations of 0, 400, and 1600 mg/kg for 5, 15, 25, and 30 generations. The results showed that the CarE activity was significantly different between different Zn2+ concentrations and different generations. The CarE activity significantly decreased with increasing generations. In the higher generations, the CarE activity was strongly inhibited by the 1600 mg/kg of Zn2+. Realtime quantitative PCR revealed that the CarE gene expression pattern in S. avenae was up-regulated under the condition of 400 mg/kg and 1600 mg/kg of Zn2+, but a significant difference was not found after long-term exposure to high concentrations of Zn2+. It was concluded that CarE could be the sensitive biomarker for S. avenae response to the presence of Zn2+. In order to adapt to heavy metal Zn2+ stress, S. avenae had particular patterns of gene expression under long-term stress.

  5. The Effects of Atmosphere on the Sintering of Ultrafine-Grained Tungsten with Ti

    NASA Astrophysics Data System (ADS)

    Ren, Chai; Koopman, Mark; Fang, Z. Zak; Zhang, Huan

    2016-11-01

    Tungsten (W) is a brittle material at room temperature making it very difficult to fabricate. Although the lack of ductility remains a difficult challenge, nano-sized and ultrafine-grained (UFG) structures offer the potential to overcome tungsten's room-temperature brittleness. One way to manufacture UFG W is to compact and sinter nano-sized W powder. It is challenging, however, to control grain growth during sintering. As one method to inhibit grain growth, the effect of Ti-based additives on the densification and grain growth of nano-W powders was investigated in this study. Addition of 1% Ti into tungsten led to more than a 63% decrease in average grain size of sintered samples at comparable density levels. It was found that sintering in Ar yielded a finer grain size than sintering in H2 at similar densities. The active diffusion mechanisms during sintering were different for W-1% Ti nano powders sintered in Ar and H2.

  6. 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

  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. Exploiting the Magnetic Origin of Solar Activity in Forecasting Thermospheric Density Variations

    DTIC Science & Technology

    2014-09-01

    Exploiting the Magnetic Origin of Solar Activity in Forecasting Thermospheric Density Variations Harry Warren Naval Research Laboratory, Space...Science Division, Washington, DC John Emmert Naval Research Laboratory, Space Science Division, Washington, DC Abstract A detailed understanding of solar ...drag. Current operational models rely on forecasts of proxies for solar activity based on autoregression. The forecasts from these models generally

  9. 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...

  10. 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

  11. 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

  12. 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.

  13. Bioturbation effects of Corophium volutator: Importance of density and behavioural activity

    NASA Astrophysics Data System (ADS)

    De Backer, A.; Van Coillie, F.; Montserrat, F.; Provoost, P.; Van Colen, C.; Vincx, M.; Degraer, S.

    2011-01-01

    Bioturbation is one of the major processes influencing ecosystem functioning. Population parameters such as species density, burrow density and species-specific life modes, determine the impact of bioturbation on the ecosystem. A laboratory experiment was developed, using microcosms mimicking a marine intertidal sediment-water interface which allowed for quantification of different population parameters. The vertical redistribution, bioturbation rate and maximum penetration depth of two sizes (41 and 129 μm) of luminophores were measured in five treatments (control, low density of burrows with and without Corophium (1989 ind./m 2), and high density of burrows with and without Corophium (14,921 ind./m 2)) after 1, 7 and 14 days. Results indicate that the behavioural activities of Corophium are of the utmost importance in sediment reworking, since they contributed to a five-fold increase in bioturbation rate compared to the passive transport induced by the static structure of the burrows. Furthermore, density is an important parameter because only high densities play a prominent role in particle transport and hence in organic matter processing, while the role of low Corophium densities is limited in sediment reworking. No evidence for differentiation in sediment size fractions was observed. Finally, bioturbation rates in this study were low compared to other studies, and these results suggest an influence of the tidal rhythmicity in the behavioural activity of Corophium on the bioturbation rate.

  14. The QTL GNP1 Encodes GA20ox1, Which Increases Grain Number and Yield by Increasing Cytokinin Activity in Rice Panicle Meristems

    PubMed Central

    Mi, Xue-Fei; Shan, Jun-Xiang; Xu, Jian-Long

    2016-01-01

    Cytokinins and gibberellins (GAs) play antagonistic roles in regulating reproductive meristem activity. Cytokinins have positive effects on meristem activity and maintenance. During inflorescence meristem development, cytokinin biosynthesis is activated via a KNOX-mediated pathway. Increased cytokinin activity leads to higher grain number, whereas GAs negatively affect meristem activity. The GA biosynthesis genes GA20oxs are negatively regulated by KNOX proteins. KNOX proteins function as modulators, balancing cytokinin and GA activity in the meristem. However, little is known about the crosstalk among cytokinin and GA regulators together with KNOX proteins and how KNOX-mediated dynamic balancing of hormonal activity functions. Through map-based cloning of QTLs, we cloned a GA biosynthesis gene, Grain Number per Panicle1 (GNP1), which encodes rice GA20ox1. The grain number and yield of NIL-GNP1TQ were significantly higher than those of isogenic control (Lemont). Sequence variations in its promoter region increased the levels of GNP1 transcripts, which were enriched in the apical regions of inflorescence meristems in NIL-GNP1TQ. We propose that cytokinin activity increased due to a KNOX-mediated transcriptional feedback loop resulting from the higher GNP1 transcript levels, in turn leading to increased expression of the GA catabolism genes GA2oxs and reduced GA1 and GA3 accumulation. This rebalancing process increased cytokinin activity, thereby increasing grain number and grain yield in rice. These findings uncover important, novel roles of GAs in rice florescence meristem development and provide new insights into the crosstalk between cytokinin and GA underlying development process. PMID:27764111

  15. The effect of electronic energy loss on irradiation-induced grain growth in nanocrystalline oxides.

    PubMed

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

    2014-05-07

    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 irradiation-induced 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.

  16. Effects of cell density, light intensity and mixing on Undaria pinnatifida gametophyte activity in a photobioreactor.

    PubMed

    Zou, Ning; Zhou, Baicheng; Li, Bingjun; Sun, Donghong; Zeng, Chengkui

    2003-07-01

    An on-line controlled 7 l sterilizable photobioreactor was used for the optimisation of a culture of gametophytes of Undaria pinnatifida. The gametophytes, which had been stored for three years in a culture cabinet at 16 degrees C, could rapidly grow in the photobioreactor under controlled conditions. The rate of increase of dissolved oxygen and pH were used to monitor the photosynthetic activity. Optimal gametophytes density changed varying the light intensity. The optimal cell densities were 3.24 and 3.45 g FW l(-1) when the cultures were exposed to 61.7 and 82.3 microE m(-2) s(-1), respectively. The optimal cell density was higher under a high photon flux density (PFD) than under low PFD. On the other hand, the optimal light intensities were different for different cell density cultures. The light saturation point was higher at high cell density cultures than at low cell density cultures. The optimal rotational speed was 150 rpm for high cell density culture in the photobioreactor.

  17. Global exospheric temperatures and densities under active solar conditions. [measured by OGO-6

    NASA Technical Reports Server (NTRS)

    Wydra, B. J.

    1975-01-01

    Temperatures measured by the OGO-6 satellite using the 6300 A airglow spectrum are compared with temperatures derived from total densities and N2 densities. It is shown that while the variation of the total densities with latitude and magnetic activity agree well with values used for CIRA (1972), the temperature behavior is very different. While the temperatures derived from the N2 density were in much better agreement there were several important differences which radically affect the pressure gradients. The variation of temperature with magnetic activity indicated a seasonal and local time effect and also a latitude and delay time variation different from previous density derived temperatures. A new magnetic index is proposed that is better correlated with the observed temperatures. The temperature variations at high latitudes were examined for three levels of magnetic activity for both solstices and equinox conditions. A temperature maximum in the pre-midnight sector and a minimum in the noon sector were noted and seasonal and geomagnetic time and latitude effects discussed. Neutral temperature, density, pressure and boundary oxygen variations for the great storm of March 8, 1970 are presented.

  18. Grains of paradise (Aframomum melegueta) extract activates brown adipose tissue and increases whole-body energy expenditure in men.

    PubMed

    Sugita, Jun; Yoneshiro, Takeshi; Hatano, Takuya; Aita, Sayuri; Ikemoto, Takeshi; Uchiwa, Hideyo; Iwanaga, Toshihiko; Kameya, Toshimitsu; Kawai, Yuko; Saito, Masayuki

    2013-08-01

    Brown adipose tissue (BAT) is responsible for cold- and diet-induced thermogenesis, and thereby contributes to the control of whole-body energy expenditure (EE) and body fat content. BAT activity can be assessed by fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET) in human subjects. Grains of paradise (GP, Aframomum melegueta), a species of the ginger family, contain pungent, aromatic ketones such as 6-paradol, 6-gingerol and 6-shogaol. An alcohol extract of GP seeds and 6-paradol are known to activate BAT thermogenesis in small rodents. The present study aimed to examine the effects of the GP extract on whole-body EE and to analyse its relation to BAT activity in men. A total of nineteen healthy male volunteers aged 20-32 years underwent FDG-PET after 2 h of exposure to cold at 19°C with light clothing. A total of twelve subjects showed marked FDG uptake into the adipose tissue of the supraclavicular and paraspinal regions (BAT positive). The remaining seven showed no detectable uptake (BAT negative). Within 4 weeks after the FDG-PET examination, whole-body EE was measured at 27°C before and after oral ingestion of GP extract (40 mg) in a single-blind, randomised, placebo-controlled, crossover design. The resting EE of the BAT-positive group did not differ from that of the BAT-negative group. After GP extract ingestion, the EE of the BAT-positive group increased within 2 h to a significantly greater (P<0·01) level than that of the BAT-negative group. Placebo ingestion produced no significant change in EE. These results suggest that oral ingestion of GP extract increases whole-body EE through the activation of BAT in human subjects.

  19. Activity of Schinus areira (Anacardiaceae) essential oils against the grain storage pest Tribolium castaneum.

    PubMed

    Descamps, Lilian R; Sánchez Chopa, Carolina; Ferrero, Adriana A

    2011-06-01

    Essential oils extracted from leaves and fruits of Schinus areira (Anacardiaceae) were tested for their repellent, toxic and feeding deterrent properties against Tribolium castaneum (Coleoptera: Tenebrionidae) larvae and adults. A topical application assay was employed for the contact toxicity study and filter paper impregnation for the fumigant assay. A treated diet was also used to evaluate the repellent activity and a flour disk bioassay for the feeding deterrent action and nutritional index alteration. The essential oil of the leaves contained mainly monoterpenoids, with alpha-phellandrene, 3-carene and camphene predominant, whereas that from the fruits contained mainly alpha-phellandrene, 3-carene and beta-myrcene. The leaf essential oil showed repellent effects, whereas that from the fruit was an attractant. Both oils produced mortality against larvae in topical and fumigant bioassays, but fumigant toxicity was not found against adults. Moreover, both essential oils produced some alterations in nutritional index. These results show that the essential oils from S. areira could be applicable to the management of populations of Tribolium castaneum.

  20. Chemical composition and insecticidal activity of the essential oil of Illicium pachyphyllum fruits against two grain storage insects.

    PubMed

    Liu, Peng; Liu, Xin-Chao; Dong, Hui-Wen; Liu, Zhi-Long; Du, Shu-Shan; Deng, Zhi-Wei

    2012-12-13

    The aim of this research was to determine chemical composition and insecticidal activity of the essential oil of Illicium pachyphyllum fruits against two grain storage insects, Sitophilus zeamais and Tribolium castaneum, and to isolate any insecticidal constituents from the essential oil. The essential oil of I. pachyphyllum fruits was obtained by hydrodistillation and analyzed by GC-MS. A total of 36 components of the essential oil were identified, with the principal compounds in the essential oil being trans-ρ-mentha-1(7),8-dien-2-ol (24.56%), D-limonene (9.79%), caryophyllene oxide (9.32%), and cis-carveol (5.26%) followed by β-caryophyllene (4.63%) and bornyl acetate. Based on bioactivity-guided fractionation, the three active constituents were isolated and identified as trans-ρ-mentha-1(7),8-dien-2-ol, D-limonene and caryophyllene oxide. The essential oil of I. pachyphyllum fruits exhibited contact toxicity against S. zeamais and T. castaneum adults, with LD(50) values of 17.33 μg/adult and 28.94 μg/adult, respectively. trans-p-Mentha-1(7),8-dien-2-ol (LD(50) = 8.66 μg/adult and 13.66 μg/adult, respectively) exhibited stronger acute toxicity against S. zeamais and T. castaneum adults than either caryophyllene oxide (LD(50) = 34.09 μg/adult and 45.56 μg/adult) and D-limonene (LD(50) = 29.86 μg/adult and 20.14 μg/adult). The essential oil of I. pachyphyllum possessed fumigant toxicity against S. zeamais and T. castaneum adults with LC(50) values of 11.49 mg/L and 15.08 mg/L, respectively. trans-p-Mentha-1(7),8-dien-2-ol exhibited stronger fumigant toxicity against S. zeamais and T. castaneum adults, respectively, with LC(50) values of 6.01 mg/L and 8.14 mg/L, than caryophyllene oxide (LC(50) = 17.02 mg/L and 15.98 mg/L) and D-limonene (LC(50) = 33.71 mg/L and 21.24 mg/L). The results indicate that the essential oil of I. pachyphyllum fruits and its constituent compounds have potential for development into natural insecticides or fumigants for the

  1. Critical behavior of subcellular density organization during neutrophil activation and migration

    PubMed Central

    Baker-Groberg, Sandra M.; Phillips, Kevin G.; Healy, Laura D.; Itakura, Asako; Porter, Juliana E.; Newton, Paul K.; Nan, Xiaolin; McCarty, Owen J.T.

    2015-01-01

    Physical theories of active matter continue to provide a quantitative understanding of dynamic cellular phenomena, including cell locomotion. Although various investigations of the rheology of cells have identified important viscoelastic and traction force parameters for use in these theoretical approaches, a key variable has remained elusive both in theoretical and experimental approaches: the spatiotemporal behavior of the subcellular density. The evolution of the subcellular density has been qualitatively observed for decades as it provides the source of image contrast in label-free imaging modalities (e.g., differential interference contrast, phase contrast) used to investigate cellular specimens. While these modalities directly visualize cell structure, they do not provide quantitative access to the structures being visualized. We present an established quantitative imaging approach, non-interferometric quantitative phase microscopy, to elucidate the subcellular density dynamics in neutrophils undergoing chemokinesis following uniform bacterial peptide stimulation. Through this approach, we identify a power law dependence of the neutrophil mean density on time with a critical point, suggesting a critical density is required for motility on 2D substrates. Next we elucidate a continuum law relating mean cell density, area, and total mass that is conserved during neutrophil polarization and migration. Together, our approach and quantitative findings will enable investigators to define the physics coupling cytoskeletal dynamics with subcellular density dynamics during cell migration. PMID:26640599

  2. 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.

  3. Grain Physics and Infrared Dust Emission in Active Galactic Nucleus Environments

    NASA Astrophysics Data System (ADS)

    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 1046 erg s-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 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 (sime 100 K) from dense dusty gas within <=1 kpc reradiating the AGN UV emission.

  4. Seasonal and solar activity variability of D-region electron density at 69°N

    NASA Astrophysics Data System (ADS)

    Singer, Werner; Latteck, Ralph; Friedrich, Martin; Wakabayashi, Makato; Rapp, Markus

    2011-06-01

    A narrow beam Doppler radar operating at 3.17 MHz and installed close to the Andøya Rocket Range in Andenes, Norway, (69.3°N, 16.0°E) has been providing electron densities in the lower ionosphere since summer 2003. The experiment utilizes partial reflection of ordinary and extraordinary component waves from scatterers in the altitude range 50-95 km to estimate electron densities from differential absorption and differential phase measurements. These ground-based observations are in good agreement with concurrent rocket-borne radio wave propagation measurements at Andenes. Results of the diurnal and seasonal variability of electron densities and the response of D-region electron densities to solar activity storms are presented.

  5. Natural leaf senescence: probed by chlorophyll fluorescence, CO2 photosynthetic rate and antioxidant enzyme activities during grain filling in different rice cultivars.

    PubMed

    Panda, Debabrata; Sarkar, Ramani Kumar

    2013-01-01

    Natural leaf senescence was investigated in four rainfed lowland rice cultivars, FR 13A (tolerant to submergence), Sabita and Sarala (adapted to medium depth, 0-50 cm stagnant flooding) and Dengi (conventional farmers' cultivar). Changes in the levels of pigment content, CO2 photosynthetic rate, photosystem II photochemistry and anti-oxidant enzyme activities of flag leaves during grain-filling stage were investigated. Chlorophyll content, photochemical efficiency of photosystem II and CO2 photosynthetic rate decreased significantly with the progress of grain-filling. Likely, the activities of antioxidant enzymes namely, superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase decreased with progress of grain-filling. A substantial difference was observed among the four cultivars for the sustainability index (SI) of different photosynthetic parameters and antioxidant enzyme activities; SIs of those parameters, in general, were lower in low yielding cultivar FR 13A compared to the other three cultivars. Among the four cultivars Sabita gave maximum grain yield. Yet, SI of Pn was greater in Sarala and Dengi compared to the Sabita. SIs of electron transport (ETo/CS), maximal photochemical efficiency (Fv/Fm), area above Fo and Fm, catalase and ascorbate peroxidase were also greater in Sarala and Dengi. The data showed that among the different Chl a fluorescence parameters, PI could be used with greater accuracy to distinguish slow and fast senescence rice cultivars during grain-filling period. It was concluded that maintaining the vitality of rice plants during grain-filling gave guarantee to synthesize carbohydrate, however greater yield could be realized provided superior yield attributing parameters are present.

  6. Unc-51 controls active zone density and protein composition by downregulating ERK signaling.

    PubMed

    Wairkar, Yogesh P; Toda, Hirofumi; Mochizuki, Hiroaki; Furukubo-Tokunaga, Katsuo; Tomoda, Toshifumi; Diantonio, Aaron

    2009-01-14

    Efficient synaptic transmission requires the apposition of neurotransmitter release sites opposite clusters of postsynaptic neurotransmitter receptors. Transmitter is released at active zones, which are composed of a large complex of proteins necessary for synaptic development and function. Many active zone proteins have been identified, but little is known of the mechanisms that ensure that each active zone receives the proper complement of proteins. Here we use a genetic analysis in Drosophila to demonstrate that the serine threonine kinase Unc-51 acts in the presynaptic motoneuron to regulate the localization of the active zone protein Bruchpilot opposite to glutamate receptors at each synapse. In the absence of Unc-51, many glutamate receptor clusters are unapposed to Bruchpilot, and ultrastructural analysis demonstrates that fewer active zones contain dense body T-bars. In addition to the presence of these aberrant synapses, there is also a decrease in the density of all synapses. This decrease in synaptic density and abnormal active zone composition is associated with impaired evoked transmitter release. Mechanistically, Unc-51 inhibits the activity of the MAP kinase ERK to promote synaptic development. In the unc-51 mutant, increased ERK activity leads to the decrease in synaptic density and the absence of Bruchpilot from many synapses. Hence, activated ERK negatively regulates synapse formation, resulting in either the absence of active zones or the formation of active zones without their proper complement of proteins. The Unc-51-dependent inhibition of ERK activity provides a potential mechanism for synapse-specific control of active zone protein composition and release probability.

  7. 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.

  8. 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

  9. Altitude variations in the thermosphere mass density response to geomagnetic activity during the recent solar minimum

    NASA Astrophysics Data System (ADS)

    Liu, X.; Thayer, J. P.; Burns, A.; Wang, W.; Sutton, E.

    2014-03-01

    Accelerometer data from coplanar orbits of Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites were used to study the complex altitude and latitude variations of the thermosphere mass density response to geomagnetic activity during 1-10 December 2008 near 09 LT. Helium number densities near 500 km altitude were extracted from the CHAMP and GRACE measurements and clearly show the presence of a winter hemisphere helium bulge. This recent extreme solar minimum indicates that wintertime helium concentrations exceed NRLMSISE-00 model estimates by 30%-70% during quiet geomagnetic activity after adjusting F10.7 input into MSIS. The perturbation in mass density from quiet to active conditions is found to be less enhanced in the winter hemisphere at the higher GRACE altitudes (25%) than at the lower CHAMP altitudes (60%) and is attributed to dynamic behavior in the helium/oxygen transition. The investigation revealed the maximum storm time density perturbation to occur near the He/O transition region with a much weaker maximum near the O/N2 transition region. The altitude of maximum density perturbation occurs where the perturbation in the weighted pressure scale height is equal and opposite to the perturbation in the weighted mean molecular weight scale height. The altitude structure of density scale height perturbation is significantly influenced by the changes in the molecular weight scale height and can account for 50% of the change in mass density scale height in a region correspondingly close to the He/O transition during the 2008 solar minimum period.

  10. Quantitative control of active targeting of nanocarriers to tumor cells through optimization of folate ligand density.

    PubMed

    Tang, Zhaomin; Li, Dan; Sun, Huili; Guo, Xing; Chen, Yuping; Zhou, Shaobing

    2014-09-01

    The active targeting delivery system has been widely studied in cancer therapy by utilizing folate (FA) ligands to generate specific interaction between nanocarriers and folate receptors (FRs) on tumor cell. However, there is little work that has been published to investigate the influence of the definite density of the FA ligands on the active targeting of nanocarriers. In this study, we have combined magnetic-guided iron oxide nanoparticles with FA ligands, adjusted the FA ligand density and then studied the resulting effects on the active targeting ability of this dual-targeting drug delivery system to tumor cells. We have also optimized the FA ligand density of the drug delivery system for their active targeting to FR-overexpressing tumor cells in vitro. Prussian blue staining, semi-thin section of cells observed with transmission electron microscopy (TEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) have shown that the optimal FA density is from 2.3 × 10(18) to 2.5 × 10(18) per gram nanoparticles ((g·NPs)(-1)). We have further tried to qualitatively and quantitatively control the active targeting and delivering of drugs to tumors on 4T1-bearing BALB/c mice. As expected, the in vivo experimental results have also demonstrated that the FA density of the magnetic nanoparticles (MNPs) could be optimized for a more easily binding to tumor cells via the multivalent linkages and more readily internalization through the FR-mediated endocytosis. Our study can provide a strategy to quantitatively control the active targeting of nanocarriers to tumor cells for cancer therapy.

  11. Evaluating the addition of activated carbon to heat-treated mushroom casing for grain-based and compost-based substrates.

    PubMed

    Bechara, Mark A; Heinemann, P H; Walker, P N; Demirci, A; Romaine, C P

    2009-10-01

    Two substrates, a non-composted grain spawn substrate and a traditional composted substrate, each covered with peat-based casing that contained varying amounts of activated carbon (AC) and each receiving different heat-treatment durations, were tested for Agaricus bisporus mushroom production. The amounts of AC were 0, 5, 10, 15, and 20% v/v, and the heat treatments were 0, 60, and 180 min at 121 degrees C and 103.4 kPa. Overall, the addition of AC up to 10-15% of casing for a grain spawn substrate increased mushroom yield. However, the addition of AC to the casing for compost substrates had no significant effect on yield, whereas heat-treating the casing increased yield. The onset of fruiting was retarded in grain spawn treatments not receiving AC with heat-treatment durations of 60 and 180 min, whereas this effect was not as apparent for the compost substrates. On average, mushroom yield was greater for the grain spawn substrate (366 g) than for compost substrate (287 g). For grain spawn substrate, the results show that the addition of AC ranging from 5% to 10% was adequate for maximum mushroom production.

  12. 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.

  13. 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.

  14. Direct effects of tillage on the activity density of ground beetle (Coleoptera: Carabidae) weed seed predators.

    PubMed

    Shearin, A F; Reberg-Horton, S C; Gallandt, E R

    2007-10-01

    Ground beetles are well known as beneficial organisms in agroecosystems, contributing to the predation of a wide range of animal pests and weed seeds. Tillage has generally been shown to have a negative effect on ground beetles, but it is not known whether this is because of direct mortality or the result of indirect losses resulting from dispersal caused by habitat deterioration. In 2005, field experiments measured direct, tillage-induced mortality, of four carabid weed seed predators, Harpalus rufipes DeGeer, Agonum muelleri Herbst, Anisodactylus merula Germar, and Amara cupreolata Putzeys, and one arthropod predator, Pterostichus melanarius Illiger, common to agroecosystems in the northeastern United States. Three tillage treatments (moldboard plow, chisel plow, and rotary tillage) were compared with undisturbed controls at two sites (Stillwater and Presque Isle) and at two dates (July and August) in Maine. Carabid activity density after disturbance was measured using fenced pitfall traps installed immediately after tillage to remove any effects of dispersal. Rotary tillage and moldboard plowing reduced weed seed predator activity density 52 and 54%, respectively. Carabid activity density after chisel plowing was similar to the undisturbed control. This trend was true for each of the weed seed predator species studied. However, activity density of the arthropod predator P. melanarius was reduced by all tillage types, indicating a greater sensitivity to tillage than the four weed seed predator species. These results confirm the need to consider both direct and indirect effects of management in studies of invertebrate seed predators.

  15. Electron-density descriptors as predictors in quantitative structure--activity/property relationships and drug design.

    PubMed

    Matta, Chérif F; Arabi, Alya A

    2011-06-01

    The use of electron density-based molecular descriptors in drug research, particularly in quantitative structure--activity relationships/quantitative structure--property relationships studies, is reviewed. The exposition starts by a discussion of molecular similarity and transferability in terms of the underlying electron density, which leads to a qualitative introduction to the quantum theory of atoms in molecules (QTAIM). The starting point of QTAIM is the topological analysis of the molecular electron-density distributions to extract atomic and bond properties that characterize every atom and bond in the molecule. These atomic and bond properties have considerable potential as bases for the construction of robust quantitative structure--activity/property relationships models as shown by selected examples in this review. QTAIM is applicable to the electron density calculated from quantum-chemical calculations and/or that obtained from ultra-high resolution x-ray diffraction experiments followed by nonspherical refinement. Atomic and bond properties are introduced followed by examples of application of each of these two families of descriptors. The review ends with a study whereby the molecular electrostatic potential, uniquely determined by the density, is used in conjunction with atomic properties to elucidate the reasons for the biological similarity of bioisosteres.

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

    PubMed Central

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

    2015-01-01

    [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

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

    NASA Astrophysics Data System (ADS)

    DeCost, Brian L.; Holm, Elizabeth A.

    2016-07-01

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

  18. Replacing with whole grains and legumes reduces Lp-PLA2 activities in plasma and PBMCs in patients with prediabetes or T2D.

    PubMed

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

    2014-08-01

    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.

  19. Erosion and deposition by supercritical density flows during channel avulsion and backfilling: Field examples from coarse-grained deepwater channel-levée complexes (Sandino Forearc Basin, southern Central America)

    NASA Astrophysics Data System (ADS)

    Lang, Jörg; Brandes, Christian; Winsemann, Jutta

    2017-03-01

    Erosion and deposition by supercritical density flows can strongly impact the facies distribution and architecture of submarine fans. Field examples from coarse-grained channel-levée complexes from the Sandino Forearc Basin (southern Central America) show that cyclic-step and antidune deposits represent common sedimentary facies of these depositional systems and relate to the different stages of avulsion, bypass, levée construction and channel backfilling. During channel avulsion, large-scale scour-fill complexes (18 to 29 m deep, 18 to 25 m wide, 60 to > 120 m long) were incised by supercritical density flows. The multi-storey infill of the large-scale scour-fill complexes comprises amalgamated massive, normally coarse-tail graded or widely spaced subhorizontally stratified conglomerates and pebbly sandstones, interpreted as deposits of the hydraulic-jump zone of cyclic steps. The large-scale scour-fill complexes can be distinguished from small-scale channel fills based on the preservation of a steep upper margin and a coarse-grained infill comprising mainly amalgamated hydraulic-jump zone deposits. Channel fills include repeated successions deposited by cyclic steps with superimposed antidunes. The deposits of the hydraulic-jump zone of cyclic steps comprise regularly spaced scours (0.2 to 2.6 m deep, 0.8 to 23 m long) infilled by intraclast-rich conglomerates or pebbly sandstones, displaying normal coarse-tail grading or backsets. These deposits are laterally and vertically associated with subhorizontally stratified, low-angle cross-stratified or sinusoidally stratified sandstones and pebbly sandstones, which were deposited by antidunes on the stoss side of the cyclic steps during flow re-acceleration. The field examples indicate that so-called spaced stratified deposits may commonly represent antidune deposits with varying stratification styles controlled by the aggradation rate, grain-size distribution and amalgamation. The deposits of small-scale cyclic

  20. 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.

  1. 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.

  2. North-south asymmetry in activity on the Sun and cosmic ray density gradients

    NASA Technical Reports Server (NTRS)

    Swinson, D. B.; Shea, M. A.; Humble, J. E.

    1985-01-01

    The marked N-S asymmetry in solar activity (with predominant activity in the Sun's Northern Hemisphere) during the 1960's could certainly account for a S-pointing cosmic ray gradient. It is also clear from the data that the response to this change in solar activity asymmetry, and the related change in the perpendicular cosmic ray density gradient, is different for cosmic ray telescopes in the Earth's Northern and Southern Hemispheres. Northern Hemisphere detectors see a S-pointing gradient in the 60's and a N-pointing gradient after 1971, while Southern Hemisphere telescopes see a S-pointing gradient both before and after the reversal.

  3. 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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. 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

  7. 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.

  8. Presolar Grains

    NASA Astrophysics Data System (ADS)

    Zinner, E. K.

    2003-12-01

    Traditionally, astronomers have studied the stars by using, with rare exception, electromagnetic radiation received by telescopes on and above the Earth. Since the mid-1980s, an additional observational window has been opened in the form of microscopic presolar grains found in primitive meteorites. These grains had apparently formed in stellar outflows of late-type stars and in the ejecta of stellar explosions and had survived the formation of the solar system. They can be located in and extracted from their parent meteorites and studied in detail in the laboratory. Their stellar origin is recognized by their isotopic compositions, which are completely different from those of the solar system and, for some elements, cover extremely wide ranges, leaving little doubt that the grains are ancient stardust.By the 1950s it had been conclusively established that the elements from carbon on up are produced by nuclear reactions in stars and the classic papers by Burbidge et al. (1957) and Cameron (1957) provided a theoretical framework for stellar nucleosynthesis. According to these authors, nuclear processes produce elements with very different isotopic compositions, depending on the specific stellar source. The newly produced elements are injected into the interstellar medium (ISM) by stellar winds or as supernova (SN) ejecta, enriching the galaxy in "metals" (all elements heavier than helium) and after a long galactic history the solar system is believed to have formed from a mix of this material. In fact, the original work by Burbidge et al. and Cameron was stimulated by the observation of regularities in the abundance of the nuclides in the solar system as obtained by the study of meteorites (Suess and Urey, 1956). Although providing only a grand average of many stellar sources, the solar system abundances of the elements and isotopes ( Anders and Grevesse, 1989; Grevesse et al., 1996; see Chapter 1.03; Lodders, 2003) remained an important test for nucleosynthesis

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Activated Carbon Fiber Paper Based Electrodes with High Electrocatalytic Activity for Vanadium Flow Batteries with Improved Power Density.

    PubMed

    Liu, Tao; Li, Xianfeng; Xu, Chi; Zhang, Huamin

    2017-02-08

    Vanadium flow batteries (VFBs) have received high attention for large-scale energy storage due to their advantages of flexibility design, long cycle life, high efficiency, and high safety. However, commercial progress of VFBs has so far been limited by its high cost induced by its low power density. Ultrathin carbon paper is believed to be a very promising electrode for VFB because it illustrates super-low ohmic polarization, however, is limited by its low electrocatalytic activity. In this paper, a kind of carbon paper (CP) with super-high electrocatalytic activity was fabricated via a universal and simple CO2 activation method. The porosity and oxygen functional groups can be easily tuned via this method. The charge transfer resistance (denoting the electrochemical polarization) of a VFB with CP electrode after CO2 activation decreased dramatically from 970 to 120 mΩcm(2). Accordingly, the energy efficiency of a VFB with activated carbon paper as the electrode increased by 13% as compared to one without activation and reaches nearly 80% when the current density is 140 mAcm(-2). This paper provides an effective way to prepare high-performance porous carbon electrodes for VFBs and even for other battery systems.

  14. 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.

  15. 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.

  16. Selective regulation of current densities underlies spontaneous changes in the activity of cultured neurons.

    PubMed

    Turrigiano, G; LeMasson, G; Marder, E

    1995-05-01

    We study the electrical activity patterns and the expression of conductances in adult stomatogastric ganglion (STG) neurons as a function of time in primary cell culture. When first plated in culture, these neurons had few active properties. After 1 d in culture they produced small action potentials that rapidly inactivated during maintained depolarization. After 2 d in culture they fired large action potentials tonically when depolarized, and their properties resembled very closely the properties of STG neurons pharmacologically isolated in the ganglion. After 3-4 d in culture, however, their electrical properties changed and they fired in bursts when depolarized. We characterized the currents expressed by these neurons in culture. They included two TTX-sensitive sodium currents, a calcium current, a delayed-rectifier-like current, a calcium-dependent potassium current, and two A-type currents. The changes in firing properties with time in culture were accompanied by an increase in inward and decrease in outward current densities. A single-compartment conductance-based model of an STG neuron was constructed by fitting the currents measured in the biological neurons. When the current densities in the model neuron were matched to those measured for the biological neurons in each activity state, the model neuron closely reproduced each state, indicating that the changes in current densities are sufficient to account for the changes in intrinsic properties. These data indicate that STG neurons isolated in culture change their intrinsic electrical properties by selectively adjusting the magnitudes of their ionic conductances.

  17. 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.

  18. 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.

  19. 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.

  20. The physics of grain-grain collisions and gas-grain sputtering in interstellar shocks

    NASA Technical Reports Server (NTRS)

    Tielens, A. G. G. M.; Mckee, C. F.; Seab, C. G.; Hollenbach, D. J.

    1994-01-01

    Grain-grain collisions and ion sputtering destroy dust grains in interstellar shocks. An analytical theory is developed for the propagation of shock waves in solids driven by grain-grain collisions, which compares very favorably with detailed numerical calculations. This theory is used to determine the fraction of grain vaporized by a grain-grain collision. Our results predict much less vaporization of colliding grains in interstellar shocks than previous estimates. This theory can also be used to determine the fraction of a colliding grain that melts, shatter, or undergoes a phase transformation to a higher density phase. In particular, the latter two processes can be much more important in interstellar shocks than vaporization. The sputtering of grains by impacting gas ions is reanalyzed based upon extensive laboratory studies and a theoretically derived 'universal'sputtering relation. The analytical results are compared to available experimental studies of sputtering of graphite/amorphous carbon, SiO2, SiC, Fe, and H2O. Sputtering yields for astrophysically relevant materials as a function of impact energy and ion mass are derived. These yields are also averaged over thermal impact spectrum and simple polynomial fits to the resulting yields as a function of temperature are presented. The derived sputtering yields are similar to those adopted in previous studies, except for graphite near threshold where the new yields are much larger due to a lower adopted binding energy. The ion bombardment will amorphitize the surface layers of interstellar grains. It will also convert graphite into hydrogenated amorphous carbon (HAC) to a depth of 10-20 A. It is suggested that these HAC surfaces are the carriers of the 3.4 micrometer absorption feature in the interstellar medium.

  1. 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

  2. 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.

  3. Enhanced detection of lipid transfer inhibitor protein activity by an assay involving only low density lipoprotein.

    PubMed

    Morton, R E; Greene, D J

    1994-11-01

    Lipid transfer inhibitor protein (LTIP) activity has been typically quantitated by its ability to suppress lipid transfer protein-mediated lipid movement between low density lipoprotein (LDL) and high density lipoprotein (HDL). In an attempt to establish an LTIP activity assay that is more sensitive, we have exploited the reported preference of the inhibitor protein to interact with LDL. A lipid transfer assay was established that involves LDL as both the donor and the acceptor; LDL in one of these two pools was biotinylated to facilitate its removal with immobilized avidin. Compared to the standard LDL to HDL assay, LTIP inhibited lipid transfer from radiolabeled LDL to biotin-LDL 7-fold more. In the absence of LTIP, lipid transfer activity was the same in both assays. An added benefit of this assay was the near linearity (up to 85%) of the inhibitory response, in contrast to the highly curvilinear response of LTIP in LDL to HDL transfer assays. The high sensitivity of the LDL to biotin-LDL transfer assay in measuring LTIP activity could not be duplicated by other transfer assays including assays containing only HDL (HDL to biotin-HDL), assays between liposomes and LDL, or assays between LDL and HDL where the concentration of lipoproteins was reduced 10-fold. Thus, LTIP activity is most effectively measured in homologous lipid transfer assays involving only LDL (and its biotin derivative). This increased sensitivity to LTIP suggests that the inhibitor binds more avidly to the LDL surface than does lipid transfer protein.

  4. Screening of active metals for reactive adsorption desulfurization adsorbent using density functional theory

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Zhao, Liang; Xu, Chunming; Wang, Yuxian; Gao, Jinsen

    2017-03-01

    To explore characteristics of active metals for reactive adsorption desulfurization (RADS) technology, the adsorption of thiophene on M (100) (M = Cr, Mo, Co, Ni, Cu, Au, and Ag) surfaces was systematically studied by density functional theory with vdW correction (DFT + D3). We found that, in all case, the most stable molecular adsorption site was the hollow site and adsorptive capabilities of thiophene followed the order: Cr > Mo > Co ≈ Ni > Cu > Au ≈ Ag. By analyzing the nature of binding between thiophene and corresponding metals and the electronic structure of metals, the excessive activities of Cr and Mo were found to have a negative regeneration, the passive activities of Au and Ag were found to have an inactive adsorption for RADS adsorbent alone, while Ni and Co have appropriate characteristics as the active metals for RADS, followed by Cu.

  5. Living Clusters and Crystals from Low-Density Suspensions of Active Colloids

    NASA Astrophysics Data System (ADS)

    Mognetti, B. M.; Šarić, A.; Angioletti-Uberti, S.; Cacciuto, A.; Valeriani, C.; Frenkel, D.

    2013-12-01

    Recent studies aimed at investigating artificial analogs of bacterial colonies have shown that low-density suspensions of self-propelled particles confined in two dimensions can assemble into finite aggregates that merge and split, but have a typical size that remains constant (living clusters). In this Letter, we address the problem of the formation of living clusters and crystals of active particles in three dimensions. We study two systems: self-propelled particles interacting via a generic attractive potential and colloids that can move toward each other as a result of active agents (e.g., by molecular motors). In both cases, fluidlike “living” clusters form. We explain this general feature in terms of the balance between active forces and regression to thermodynamic equilibrium. This balance can be quantified in terms of a dimensionless number that allows us to collapse the observed clustering behavior onto a universal curve. We also discuss how active motion affects the kinetics of crystal formation.

  6. Experimental characterization of active acoustic metamaterial cell with controllable dynamic density

    NASA Astrophysics Data System (ADS)

    Akl, Wael; Baz, Amr

    2012-10-01

    Controlling wave propagation pattern within acoustic fluid domains has been the motivation for the acoustic metamaterials developments to target applications ranging from acoustic cloaking to passive noise control techniques. Currently, various numerical and analytical approaches exist to predict the fluid domain material properties necessary for specific propagation pattern. Physical attempts to realize such material properties have revealed engineered material constructions that are focused on predefined wave propagation patterns. In the current paper, coupled fluid-structure one-dimensional metamaterial cell, in which piezoelectric active ingredient has been introduced, is manufactured to achieve controllable dynamic density. The density-controllable cell has been manufactured by coupling a water-filled cavity with piezoelectric elements in a cell of 4.5 cm length and 4.1 cm diameter subject to impulse excitation. A finite element model of the cell has been developed and its predictions are validated against the experimental results. The validated model is utilized to predict the changes in the pressure gradient inside the developed cell which is a direct measure of the changes introduced to the dynamic density of the acoustic metamaterial domain. With such predictions, it is demonstrated that densities as high as 3.2 gm/cm3 and as low as 0.72 gm/cm3 can be achieved experimentally for excitation frequencies ranging between 100 Hz and 500 Hz.

  7. Quantitative analysis of axonal fiber activation evoked by deep brain stimulation via activation density heat maps

    PubMed Central

    Hartmann, Christian J.; Chaturvedi, Ashutosh; Lujan, J. Luis

    2015-01-01

    Background: Cortical modulation is likely to be involved in the various therapeutic effects of deep brain stimulation (DBS). However, it is currently difficult to predict the changes of cortical modulation during clinical adjustment of DBS. Therefore, we present a novel quantitative approach to estimate anatomical regions of DBS-evoked cortical modulation. Methods: Four different models of the subthalamic nucleus (STN) DBS were created to represent variable electrode placements (model I: dorsal border of the posterolateral STN; model II: central posterolateral STN; model III: central anteromedial STN; model IV: dorsal border of the anteromedial STN). Axonal fibers of passage near each electrode location were reconstructed using probabilistic tractography and modeled using multi-compartment cable models. Stimulation-evoked activation of local axon fibers and corresponding cortical projections were modeled and quantified. Results: Stimulation at the border of the STN (models I and IV) led to a higher degree of fiber activation and associated cortical modulation than stimulation deeply inside the STN (models II and III). A posterolateral target (models I and II) was highly connected to cortical areas representing motor function. Additionally, model I was also associated with strong activation of fibers projecting to the cerebellum. Finally, models III and IV showed a dorsoventral difference of preferentially targeted prefrontal areas (models III: middle frontal gyrus; model IV: inferior frontal gyrus). Discussion: The method described herein allows characterization of cortical modulation across different electrode placements and stimulation parameters. Furthermore, knowledge of anatomical distribution of stimulation-evoked activation targeting cortical regions may help predict efficacy and potential side effects, and therefore can be used to improve the therapeutic effectiveness of individual adjustments in DBS patients. PMID:25713510

  8. Shear-Coupled Grain Growth and Texture Development in a Nanocrystalline Ni-Fe Alloy during Cold Rolling

    NASA Astrophysics Data System (ADS)

    Li, Li; Ungár, Tamás; Toth, Laszlo S.; Skrotzki, Werner; Wang, Yan Dong; Ren, Yang; Choo, Hahn; Fogarassy, Zsolt; Zhou, X. T.; Liaw, Peter K.

    2016-12-01

    The evolution of texture, grain size, grain shape, dislocation, and twin density has been determined by synchrotron X-ray diffraction and line profile analysis in a nanocrystalline Ni-Fe alloy after cold rolling along different directions related to the initial fiber and the long axis of grains. The texture evolution has been simulated by the Taylor-type relaxed-constraints viscoplastic polycrystal model. The simulations were based on the activity of partial dislocations in correlation with the experimental results of dislocation density determination. The concept of stress-induced shear coupling is supported and strengthened by both the texture simulations and the experimentally determined evolution of the microstructure parameters. Grain growth and texture evolution are shown to proceed by the shear coupling mechanism supported by dislocation activity as long as the grain size is not smaller than about 20 nm.

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

    PubMed

    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.

  10. 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.

  11. Thermospheric topside neutral density, ionospheric anomalous electric field and resistivity measurements by active experiment at EISCAT

    NASA Astrophysics Data System (ADS)

    Kosch, Michael; Ogawa, Yasunobu; Rietveld, Michael; Blagoveshchenskaya, Nataly; Yamazaki, Yosuke

    2016-07-01

    We have developed an active ground-based technique to estimate the topside thermospheric neutral density as well as topside ionospheric anomalous electric field and resistivity at EISCAT, combining the EISCAT UHF radar, HF heater and optics. When pumping the ionosphere the F-region electron temperature is significantly raised, increasing the upward plasma pressure gradient in the topside ionosphere, resulting in observed ion up-flow along the magnetic field line. Simultaneously, pump-induced suprathermal electrons produce artificial optical emissions. Using the modified ion-momentum equation, the thermospheric neutral density is estimated. Alternatively, using the MSIS model the field-aligned anomalous electric field is estimated. From the optical data the suprathermal electron flux is estimated, giving an estimate of the anomalous resistivity. Results from recent observations at EISCAT are presented.

  12. 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.

  13. 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.

  14. Tissue-type plasminogen activator suppresses activated stellate cells through low-density lipoprotein receptor-related protein 1

    PubMed Central

    Kang, Liang-I; Isse, Kumiko; Koral, Kelly; Bowen, William C; Muratoglu, Selen; Strickland, Dudley K; Michalopoulos, George K; Mars, Wendy M

    2015-01-01

    Hepatic stellate cell (HSC) activation and trans-differentiation into myofibroblast (MFB)-like cells is key for fibrogenesis after liver injury and a potential therapeutic target. Recent studies demonstrated that low-density lipoprotein receptor-related protein 1 (LRP1)-dependent signaling by tissue-type plasminogen activator (t-PA) is a pro-fibrotic regulator of the MFB phenotype in kidney. This study investigated whether LRP1 signaling by t-PA is also relevant to HSC activation following injury. Primary and immortalized rat HSCs were treated with t-PA and assayed by western blot, MTT, and TUNEL. In vitro results were then verified using an in vivo, acute carbon tetrachloride (CCl4) injury model that examined the phenotype and recovery kinetics of MFBs from wild-type animals vs mice with a global (t-PA) or HSC-targeted (LRP1) deletion. In vitro, in contrast to kidney MFBs, exogenous, proteolytically inactive t-PA suppressed, rather than induced, activation markers in HSCs following phosphorylation of LRP1. This process was mediated by LRP1 as inhibition of t-PA binding to LRP1 blocked the effects of t-PA. In vivo, following acute injury, phosphorylation of LRP1 on activated HSCs occurred immediately prior to their disappearance. Mice lacking t-PA or LRP1 retained higher densities of activated HSCs for a longer time period compared with control mice after injury cessation. Hence, t-PA, an FDA-approved drug, contributes to the suppression of activated HSCs following injury repair via signaling through LRP1. This renders t-PA a potential target for exploitation in treating patients with fibrosis. PMID:26237273

  15. Lysine-poly(2-hydroxyethyl methacrylate) modified polyurethane surface with high lysine density and fibrinolytic activity.

    PubMed

    Li, Dan; Chen, Hong; Wang, Shasha; Wu, Zhaoqiang; Brash, John L

    2011-03-01

    We have developed a potentially fibrinolytic surface in which a bioinert polymer is used as a spacer to immobilize lysine such that the ε-amino group is free to capture plasminogen when in contact with blood. Adsorbed plasminogen can be activated to plasmin and potentially dissolve nascent clots formed on the surface. In previous work lysine was immobilized through a poly(ethylene glycol) (PEG) spacer; however, the graft density of PEG was limited and the resulting adsorbed quantity of plasminogen was insufficient to dissolve clots efficiently. The aim of the present work was to optimize the surface using graft-polymerized poly(2-hydroxyethyl methacrylate) (poly(HEMA)) as a spacer to increase the grafting density of lysine. Such a poly(HEMA)-lysine modified polyurethane (PU) surface is expected to have increased plasminogen binding capacity and clot lysing efficiency compared with PEG-lysine modified PU. A lysine density of 2.81 nmol cm(-2) was measured on the PU-poly(HEMA)-Lys surface vs. 0.76 nmol cm(-2) on a comparable PU-PEG-Lys surface reported previously. The poly(HEMA)-lysine-modified surface was shown to reduce non-specific (fibrinogen) adsorption while binding plasminogen from plasma with high affinity. With increased plasminogen binding capacity these surfaces showed more rapid clot lysis (20 min) in a standard in vitro assay than the corresponding PEG-lysine system (40 min). The data suggest that poly(HEMA) is superior to PEG when used as a spacer in the immobilization of bioactive molecules at high density. This method of modification may also provide a generic approach for preparing bioactive PU surfaces of high activity and low non-specific adsorption of proteins.

  16. Enabling High Energy Density Li-Ion Batteries through Li{sub 2}O Activation.

    SciTech Connect

    Abouimrane, Ali; Cui, Yanjie; Chen, Zonghai; Belharouak, Ilias; Yahia, Hamdi B.; Wu, Huiming; Assary, Rajeev; Curtiss, Larry A.; Amine, Khalil

    2016-09-01

    Lithium oxide (Li2O) is activated in the presence of a layered composite cathode material (HEM) significantly increasing the energy density of lithium-ion batteries. The degree of activation depends on the current rate, electrolyte salt, and anode type. In full-cell tests, the Li2O was used as a lithium source to counter the first-cycle irreversibility of high-capacity composite alloy anodes. When Li2O is mixed with HEM to serve as a cathode, the electrochemical performance was improved in a full cell having an SiO-SnCoC composite as an anode. The mechanism behind the Li2O activation could also explain the first charge plateau and the abnormal high capacity associated with these high energy cathode materials.

  17. Nano-analysis of grain boundary and triple junction transport in nanocrystalline Ni/Cu.

    PubMed

    Reda Chellali, Mohammed; Balogh, Zoltan; Schmitz, Guido

    2013-09-01

    Nanocrystalline materials are distinguished by a high density of structural defects and grain boundaries. Due to the small grain size, a particular defect of the grain boundary topology, the so-called triple junction takes a dominant role for grain growth and atomic transport. We demonstrate by atom probe tomography that triple junctions in nanocrystalline Cu have 100-300 times higher diffusivity of Ni than standard high angle grain boundaries. Also, a previously unexpected systematic variation of the grain boundary width with temperature is detected. The impurity segregation layer at the grain boundaries grows from the 0.7 nm at 563 K to 2.5 nm at 643 K. This variation is clearly not controlled by simple bulk diffusion. Taking this effect into consideration, the activation energies for Ni diffusion in triple junctions and grain boundaries in Cu can be determined to be (83 ± 10) and (120 ± 15) kJ/mol, respectively. Thus, triple junctions are distinguished by considerably lower activation energy with respect to grain boundaries.

  18. RIM determines Ca2+ channel density and vesicle docking at the presynaptic active zone

    PubMed Central

    Han, Yunyun; Kaeser, Pascal S.; Südhof, Thomas C.; Schneggenburger, Ralf

    2012-01-01

    At presynaptic active zones, neurotransmitter release is initiated by the opening of voltage-gated Ca2+ channels close to docked vesicles. The mechanisms that enrich Ca2+ channels at active zones are, however, largely unknown, possibly because of the limited presynaptic accessibility of most synapses. Here, we have established a Cre-lox based conditional knock-out approach at a presynaptically accessible CNS synapse, the calyx of Held, to directly study the functions of RIM proteins. Removal of all RIM1/2 isoforms strongly reduced the presynaptic Ca2+ channel density, revealing a new role of RIM proteins in Ca2+ channel targeting. Removal of RIMs also reduced the readily-releasable pool, paralleled by a similar reduction of the number of docked vesicles, and the Ca2+ channel - vesicle coupling was decreased. Thus, RIM proteins co-ordinately regulate key functions for fast transmitter release: enabling a high presynaptic Ca2+ channel density, and vesicle docking at the active zone. PMID:21262468

  19. Ceruloplasmin as low-density lipoprotein oxidase: activation by ascorbate and dehydroascorbate.

    PubMed

    Feichtenhofer, S; Fabjan, J S; Abuja, P M

    2001-07-13

    The ability of ceruloplasmin (Cp) to oxidize low-density lipoproteins (LDL) in the presence of water-soluble antioxidants was investigated and a reaction mechanism proposed. Ascorbate strongly enhanced LDL oxidation, but only after its rapid consumption. Dehydroascorbate enhanced Cp-mediated LDL oxidation even more strongly. Lipid-soluble antioxidants and water-soluble peroxides did not show noticeable activation. However, loading of LDL with lipid hydroperoxides increased the initial oxidation rate. We conclude that Cp mediates a localized redox cycle, where reduction of Cp-Cu2+ is effected by water-soluble reductants and reoxidation by liposoluble hydroperoxides.

  20. A High Power Density Single-Phase PWM Rectifier with Active Ripple Energy Storage

    SciTech Connect

    Ning, Puqi; Wang, Ruxi; Wang, Fei; Boroyevich, Dushan

    2010-01-01

    It is well known that there exist second-order harmonic current and corresponding ripple voltage on dc bus for single phase PWM rectifiers. The low frequency harmonic current is normally filtered using a bulk capacitor in the bus which results in low power density. This paper proposed an active ripple energy storage method that can effectively reduce the energy storage capacitance. The feed-forward control method and design considerations are provided. Simulation and 15 kW experimental results are provided for verification purposes.

  1. 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…

  2. 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

  3. 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.

  4. 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

  5. Spatially resolved modeling of the combined effect of dislocations and grain boundaries on minority carrier lifetime in multicrystalline silicon

    NASA Astrophysics Data System (ADS)

    Stokkan, G.; Riepe, S.; Lohne, O.; Warta, W.

    2007-03-01

    A model for the combined effect of dislocations and grain boundaries on minority carrier lifetime has been developed. Lifetime varies with dislocation density, grain boundary misorientation, and the coincidence site lattice (CSL) nature of the boundaries. Minority carrier lifetime was measured with high spatial resolution (50 μm) using the carrier density imaging (CDI) technique on a silicon nitride passivated multicrystalline sample. Dislocation density was measured on the same sample by image recognition of optical microscope pictures of a Secco etched surface. Grain boundaries were then mapped and characterized by electron backscatter diffraction (EBSD). Lifetime was simulated based on the dislocation and grain boundary measurements. Parameters were chosen to match closely the simulated and measured maps. Very good two-dimensional (2D) correlation was obtained by assigning roughly equal importance to recombination at dislocations and grain boundaries. The value for the capture cross section, which gives the best correlation, is 4×10-14 cm-3. This is in the range of values reported for interstitial transition metals like, for instance, iron. It appears necessary to include also the effect of grain boundaries to explain recombination in low lifetime areas. Sub grain boundaries were particularly recombination active and are dominating the number of active grain boundaries.

  6. Ion density and temperature variations at altitude of 500 km during moderate seismic activity

    NASA Astrophysics Data System (ADS)

    Bardhan, Ananna; Khurana, M. S.; Bahal, B. M.; Aggarwal, Malini; Sharma, D. K.

    2017-02-01

    Ionospheric ions (O+ and H+) and temperature (Ti) as precursory parameters to seismic activity have been analysed from year 1995 till 1998, using SROSS-C2 (average altitude range of ∼500 km) satellite measurements for moderate magnitude earthquakes. The details of seismic events during this period are downloaded from United State Geological Survey (USGS) and National Earthquake Information Centre (NEIC) website. 13 seismic events of moderate magnitude (M = 4-5.5) from 1995 to 1998, using SROSS-C2 satellite measurements have been analysed. During seismic affected period, considerable decrease in the density of heavier ion - O+ and increase in the ion temperature (Ti) is observed during all the selected events. Lighter ion - H+ doesn't show any significant change. Electric field and electromagnetic emissions generated due to seismogenic activity could be the plausible initializing agents responsible for change in ion concentration and temperature values during these events.

  7. Activation volume of selected liquid crystals in the density scaling regime

    NASA Astrophysics Data System (ADS)

    Grzybowski, A.; Urban, S.; Mroz, S.; Paluch, M.

    2017-02-01

    In this paper, we demonstrate and thoroughly analyze the activation volumetric properties of selected liquid crystals in the nematic and crystalline E phases in comparison with those reported for glass-forming liquids. In the analysis, we have employed and evaluated two entropic models (based on either total or configurational entropies) to describe the longitudinal relaxation times of the liquid crystals in the density scaling regime. In this study, we have also exploited two equations of state: volumetric and activation volumetric ones. As a result, we have established that the activation volumetric properties of the selected liquid crystals are quite opposite to such typical properties of glass-forming materials, i.e., the activation volume decreases and the isothermal bulk modulus increases when a liquid crystal is isothermally compressed. Using the model based on the configurational entropy, we suggest that the increasing pressure dependences of the activation volume in isothermal conditions and the negative curvature of the pressure dependences of isothermal longitudinal relaxation times can be related to the formation of antiparallel doublets in the examined liquid crystals. A similar pressure effect on relaxation dynamics may be also observed for other material groups in case of systems, the molecules of which form some supramolecular structures.

  8. 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.

  9. Activation volume of selected liquid crystals in the density scaling regime

    PubMed Central

    Grzybowski, A.; Urban, S.; Mroz, S.; Paluch, M.

    2017-01-01

    In this paper, we demonstrate and thoroughly analyze the activation volumetric properties of selected liquid crystals in the nematic and crystalline E phases in comparison with those reported for glass-forming liquids. In the analysis, we have employed and evaluated two entropic models (based on either total or configurational entropies) to describe the longitudinal relaxation times of the liquid crystals in the density scaling regime. In this study, we have also exploited two equations of state: volumetric and activation volumetric ones. As a result, we have established that the activation volumetric properties of the selected liquid crystals are quite opposite to such typical properties of glass-forming materials, i.e., the activation volume decreases and the isothermal bulk modulus increases when a liquid crystal is isothermally compressed. Using the model based on the configurational entropy, we suggest that the increasing pressure dependences of the activation volume in isothermal conditions and the negative curvature of the pressure dependences of isothermal longitudinal relaxation times can be related to the formation of antiparallel doublets in the examined liquid crystals. A similar pressure effect on relaxation dynamics may be also observed for other material groups in case of systems, the molecules of which form some supramolecular structures. PMID:28181530

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. Cholesteryl Ester Hydroperoxides Are Biologically Active Components of Minimally Oxidized Low Density Lipoprotein*S⃞

    PubMed Central

    Harkewicz, Richard; Hartvigsen, Karsten; Almazan, Felicidad; Dennis, Edward A.; Witztum, Joseph L.; Miller, Yury I.

    2008-01-01

    Oxidation of low density lipoprotein (LDL) occurs in vivo and significantly contributes to the development of atherosclerosis. An important mechanism of LDL oxidation in vivo is its modification with 12/15-lipoxygenase (LO). We have developed a model of minimally oxidized LDL (mmLDL) in which native LDL is modified by cells expressing 12/15LO. This mmLDL activates macrophages inducing membrane ruffling and cell spreading, activation of ERK1/2 and Akt signaling, and secretion of proinflammatory cytokines. In this study, we found that many of the biological activities of mmLDL were associated with cholesteryl ester (CE) hydroperoxides and were diminished by ebselen, a reducing agent. Liquid chromatography coupled with mass spectroscopy demonstrated the presence of many mono- and polyoxygenated CE species in mmLDL but not in native LDL. Nonpolar lipid extracts of mmLDL activated macrophages, although to a lesser degree than intact mmLDL. The macrophage responses were also induced by LDL directly modified with immobilized 12/15LO, and the nonpolar lipids extracted from 12/15LO-modified LDL contained a similar set of oxidized CE. Cholesteryl arachidonate modified with 12/15LO also activated macrophages and contained a similar collection of oxidized CE molecules. Remarkably, many of these oxidized CE were found in the extracts of atherosclerotic lesions isolated from hyperlipidemic apoE–/– mice. These results suggest that CE hydroperoxides constitute a class of biologically active components of mmLDL that may be relevant to proinflammatory activation of macrophages in atherosclerotic lesions. PMID:18263582

  16. 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.

  17. 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

  18. Determination of active oxide trap density and 1/f noise mechanism in RESURF LDMOS transistors

    NASA Astrophysics Data System (ADS)

    Çelik-Butler, Z.; Mahmud, M. I.; Hao, P.; Hou, F.; Amey, B. L.; Pendharkar, S.

    2015-09-01

    The physical origin of majority charge carrier fluctuations in the SiO2 interface of Si at accumulation has been investigated and analyzed for differently processed and voltage-rated reduced surface field (RESURF), lateral-double-diffused MOS (LDMOS) transistors. Surface carrier mobility fluctuation due to remote Coulomb scattering by the trapped charge in the gate oxide is identified as the dominant physical mechanism for LDMOS 1/f noise irrespective of process technologies. A significant contribution to the measured noise has been noted from the surface majority carrier mobility fluctuation due to trapped charge at the accumulation region of the extended drain region, dominant over other sources including the surface minority charge carrier fluctuations in the channel. Active oxide trap density was characterized spatially and for the first time up to ∼0.4 eV above the conduction band-edge of Si. The interface trap density in the unstressed devices (∼8 × 106 cm-2) increased more than an order of magnitude (∼1 × 108 cm-2) after the devices were stressed for 10,000 sec at their individual worst drain current and on-resistance degradation conditions. The extracted Si/SiO2 interface trap density above the silicon conduction band edge was found to be several orders of magnitude lower than that reported for silicon mid-gap energies, even after stressing. Since the traps near the quasi-Fermi level for electrons are active in trapping-detrapping, and the Fermi level is energetically positioned above the conduction band edge of Si in the investigated devices as compared to the previously reported observations, the lower trap density obtained here is an indication for reversal of the well-known exponential trap energy distribution beyond the conduction band-edge of Si. These findings shift the focus from the channel to the gate overlap section of the extended drain and the quality of the Si/SiO2 interface in that region.

  19. 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.

  20. Characterization of ichthyocidal activity of Pfiesteria piscicida: dependence on the dinospore cell density.

    PubMed

    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.

  1. Accelerating wavefunction in density-functional-theory embedding by truncating the active basis set

    NASA Astrophysics Data System (ADS)

    Bennie, Simon J.; Stella, Martina; Miller, Thomas F.; Manby, Frederick R.

    2015-07-01

    Methods where an accurate wavefunction is embedded in a density-functional description of the surrounding environment have recently been simplified through the use of a projection operator to ensure orthogonality of orbital subspaces. Projector embedding already offers significant performance gains over conventional post-Hartree-Fock methods by reducing the number of correlated occupied orbitals. However, in our first applications of the method, we used the atomic-orbital basis for the full system, even for the correlated wavefunction calculation in a small, active subsystem. Here, we further develop our method for truncating the atomic-orbital basis to include only functions within or close to the active subsystem. The number of atomic orbitals in a calculation on a fixed active subsystem becomes asymptotically independent of the size of the environment, producing the required O ( N 0 ) scaling of cost of the calculation in the active subsystem, and accuracy is controlled by a single parameter. The applicability of this approach is demonstrated for the embedded many-body expansion of binding energies of water hexamers and calculation of reaction barriers of SN2 substitution of fluorine by chlorine in α-fluoroalkanes.

  2. Impact of dietary intake, education, and physical activity on bone mineral density among North Indian women.

    PubMed

    Kumar, Ashok; Mittal, Soniya; Orito, Seiya; Ishitani, Ken; Ohta, Hiroaki

    2010-03-01

    The aim of the study was to determine the relationship of dietary nutrients and bone mineral density (BMD) in North Indian women. This cross-sectional study was conducted from April 2006 to March 2008. Subjects included 255 healthy women, aged 20-69 years, who were relatives of patients being admitted in the hospital. Various demographic characteristics including socioeconomic status and serum parameters in relationship to BMD were evaluated. In addition, the daily dietary intake of energy, protein, fat, and calcium and the amount of physical activity were assessed. BMD at the lumbar spine, femoral neck, and Ward's triangle was measured by dual-energy X-ray absorptiometry (DXA). Body mass index (BMI), physical activity, and educational level were positively correlated with BMD. The daily intakes of energy (1563.4 +/- 267.2 kcal) and protein (48.7 +/- 8.7 g) were below the recommended dietary allowance. Daily dietary energy, protein, and calcium intakes were correlated with BMD at the lumbar spine. Stepwise multiple linear regression analyses showed that age, BMI, and physical activity were significant predictors for BMD at all sites. In addition, energy intake was also a predictor for BMD at the lumbar spine. The protein intake was associated with BMD at the spine (P = 0.02 and beta = 0.163) even after making adjustments for energy intake. Thus, dietary pattern coupled with higher education levels and greater physical activity favored bone health.

  3. Antibodies toward high-density lipoprotein components inhibit paraoxonase activity in patients with systemic lupus erythematosus.

    PubMed

    Batuca, J R; Ames, P R J; Isenberg, D A; Alves, J Delgado

    2007-06-01

    Patients with systemic lupus erythematosus (SLE) have an increased incidence of vascular disease, and oxidative stress is recognized as an important feature in this condition, despite the underlying mechanisms not being fully understood. In these patients, an interaction between lipoproteins and the immune system has been suggested, but most studies have only looked at antibodies against oxidized low-density lipoproteins. This study was undertaken to determine the presence of antibodies directed against high-density lipoproteins (HDL) and to identify a possible association between these antibodies and paraoxonase (PON), an antioxidant enzyme present in HDL. Plasma from 55 patients with SLE was collected and IgG aHDL and antiapolipoprotein A-I (aApo A-I) antibodies were assessed by enzyme-linked immunosorbent assay. Standardization of the method was performed in a control population of 150 healthy subjects. Plasma levels above 5 standard deviations of the mean of the control population were considered positive. PON activity was assessed by quantification of p-nitrophenol formation (micromol/mL/min). Patients with SLE had higher titers of aHDL (P < 0.0001) and aApo A-I (P < 0.0001) antibodies, and lower PON activity (P < 0.0001) than healthy controls. There was also a direct correlation between the titers of aHDL and aApo A-I antibodies (r = 0.61; P < 0.0001). PON activity was inversely correlated with aApo A-I (P = 0.0129) antibody levels. Anti-HDL and aApo A-I antibodies from patients with high titers were isolated and subsequently incubated with human HDL. These antibodies reduced PON activity up to a maximum of 70.2% and 78.4%, respectively. This study showed the presence of aHDL and aApo A-I antibodies in patients with SLE. These antibodies were associated with reduced PON activity in plasma, and the in vitro inhibition assay confirmed a direct inhibition of the enzyme activity.

  4. Effect of particle surface area on ice active site densities retrieved from droplet freezing spectra

    NASA Astrophysics Data System (ADS)

    Beydoun, Hassan; Polen, Michael; Sullivan, Ryan C.

    2016-10-01

    Heterogeneous ice nucleation remains one of the outstanding problems in cloud physics and atmospheric science. Experimental challenges in properly simulating particle-induced freezing processes under atmospherically relevant conditions have largely contributed to the absence of a well-established parameterization of immersion freezing properties. Here, we formulate an ice active, surface-site-based stochastic model of heterogeneous freezing with the unique feature of invoking a continuum assumption on the ice nucleating activity (contact angle) of an aerosol particle's surface that requires no assumptions about the size or number of active sites. The result is a particle-specific property g that defines a distribution of local ice nucleation rates. Upon integration, this yields a full freezing probability function for an ice nucleating particle. Current cold plate droplet freezing measurements provide a valuable and inexpensive resource for studying the freezing properties of many atmospheric aerosol systems. We apply our g framework to explain the observed dependence of the freezing temperature of droplets in a cold plate on the concentration of the particle species investigated. Normalizing to the total particle mass or surface area present to derive the commonly used ice nuclei active surface (INAS) density (ns) often cannot account for the effects of particle concentration, yet concentration is typically varied to span a wider measurable freezing temperature range. A method based on determining what is denoted an ice nucleating species' specific critical surface area is presented and explains the concentration dependence as a result of increasing the variability in ice nucleating active sites between droplets. By applying this method to experimental droplet freezing data from four different systems, we demonstrate its ability to interpret immersion freezing temperature spectra of droplets containing variable particle concentrations. It is shown that general

  5. Cell Density-Dependent Increase in Tyrosine-Monophosphorylated ERK2 in MDCK Cells Expressing Active Ras or Raf

    PubMed Central

    Kawabata, Noriyuki; Matsuda, Michiyuki

    2016-01-01

    The extracellular signal-regulated kinase (ERK) is one of the principal hub proteins that transmit growth signals from upstream oncogene products including Ras and BRaf to downstream effector proteins. However, there are both reports supporting and refuting the increase in ERK activity in cancer tissues expressing the active Ras and BRaf proteins. We considered that the cell density might account for this discrepancy. To examine this possibility, we prepared Madin-Darby canine kidney (MDCK) cells that expressed an active HRas, NRas, KRas, or BRaf and an ERK biosensor based on the principle of Förster resonance energy transfer (FRET). As we anticipated, expression of the active Ras or BRaf increased ERK activity at low cell densities. However, the ERK activity was markedly suppressed at high cell densities irrespective of the expression of the active Ras or BRaf. Western blotting analysis with Phos-tag gel revealed the decrease of tyrosine and threonine-diphosphorylated active ERK and the increase of tyrosine-monophosphorylated inactive ERK at high cell density. In addition, we found that calyculin A, an inhibitor for PPP-subfamily protein serine/threonine phosphatases, decreased the tyrosine-monophosphorylated ERK. Our study suggests that PPP-subfamily phosphatases may be responsible for cell density-dependent ERK dephosphorylation in cancer cells expressing active Ras or BRaf protein. PMID:27936234

  6. Charge density and optical properties of multicomponent crystals containing active pharmaceutical ingredients or their analogues.

    PubMed

    Gryl, Marlena

    2015-08-01

    Active pharmaceutical ingredients (APIs), through their favourable donor/acceptor spatial distribution and synthon formation flexibility, are attractive building blocks in modern materials crystallography. The optical properties of a crystal strongly depend on two factors, i.e. the spatial distribution of molecules in the crystal structure and the electronic properties of molecular building blocks (dipole moments, polarizabilities, hyperpolarizabilities). Although the latter are easy to predict through ab initio calculations, the former are not. Only a combination of experimental and theoretical charge density studies together with prediction and measurement of optical properties enable full analysis of the obtained functional material in terms of its usefulness in practical applications. This article presents design strategies of optical materials based on selected pharmaceutical molecules. Factors that contribute to molecular recognition in the four selected polar/chiral crystal phases (derived through charge density and Hirshfeld surfaces analysis) have been determined. Theoretically predicted optical properties of the molecular/ionic building blocks as well as bulk effects have been confirmed experimentally. This research is a first step in the design of novel optical materials based on push-pull molecules and APIs.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. CF₃I synthesis catalyzed by activated carbon: a density functional theory study.

    PubMed

    Hu, Yingjie; Wu, Taiping; Liu, Weizhou; Zhang, Liyang; Pan, Renming

    2014-03-13

    A revised reaction mechanism of CF3I synthesis catalyzed by activated carbon is investigated with quantum chemistry methods using density functional theory (DFT). The adsorption configurations of possible intermediates are carefully examined. The reaction pathway and related transition states are also analyzed. According to our calculations, first, the dehydrofluorination of CHF3 is catalyzed by -COOH groups, which possesses the highest barrier and is accordingly identified as the rate-determining step. Second, the difluorocarbene disproportionation over graphite (001) surface proceeds instead of dimerization. The next reaction steps involving the association of fluoromethine and trifluoromethyl, the fluorine abstractions between intermediates and the iodine abstractions by the desorbed CF3 and CF2CF3 from molecular iodine are also feasible over graphite (001) surfaces. It is also found that the coke deposition in experiments is due to the fluorine abstraction from fluoromethine. This revised mechanism is in agreement with available experimental data and our theoretical computations.

  13. Mechanistic considerations on contact-active antimicrobial surfaces with controlled functional group densities.

    PubMed

    Bieser, Arno M; Tiller, Joerg C

    2011-04-08

    A series of N-alkyl-N,N-dimethyldeoxyammonium celluloses is synthesized by converting tosyl celluloses with DBA and DDA, respectively. Surface coatings with these water-insoluble derivatives contain well-defined densities of quaternary ammonium functions and nonactive hydrophobic and hydrophilic groups. It is shown that the antimicrobial activity of such surfaces against S. aureus requires a delicate balance between DDA, BDA, and hydrophobic groups. A mechanism is proposed that involves the selective adhesion of anionic phospholipids from the bacterial cell membrane. This so-called phospholipid sponge effect is supported by the fact that all coatings could be deactivated by treatment with SDS or negatively charged phospholipids, but not with neutral phospholipids.

  14. High-density EMG E-textile systems for the control of active prostheses.

    PubMed

    Farina, Dario; Lorrain, Thomas; Negro, Francesco; Jiang, Ning

    2010-01-01

    Myoelectric control of active prostheses requires electrode systems that are easy to apply for daily repositioning of the electrodes by the user. In this study we propose the use of Smart Fabric and Interactive Textile (SFIT) systems as an alternative solution for recording high-density EMG signals for myoelectric control. A sleeve covering the upper and lower arm, which contains 100 electrodes arranged in four grids of 5 × 5 electrodes, was used to record EMG signals in 3 subjects during the execution of 9 tasks of the wrist and hand. The signals were analyzed by extracting wavelet coefficients which were classified with linear discriminant analysis. The average classification accuracy for the nine tasks was 89.1 ± 1.9 %. These results show that SFIT systems can be used as an effective way for muscle-machine interfacing.

  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. 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

  18. 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.

  19. 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.

  20. Regulation of cell cycle activity in the embryo of barley seeds during germination as related to grain hydration.

    PubMed

    Gendreau, Emmanuel; Romaniello, Sébastien; Barad, Sophie; Leymarie, Juliette; Benech-Arnold, Roberto; Corbineau, Françoise

    2008-01-01

    Various studies indicate that cell division is a post-germination phenomenon, with radicle protrusion occurring by cell elongation, while others demonstrate that induction of the cell cycle occurs in osmo-conditioned seeds prior to radicle growth. The aim of the present work was to investigate the occurrence of the cell cycle during germination as related to grain hydration, using: (i) a flow cytometry technique to estimate the percentage of cell nuclei in G(1) and G(2) phases of the cell cycle; and (ii) reverse transcription-PCR (RT-PCR) in order to characterize the expression of the genes encoding cyclin-dependent kinases (CDKA1, CDKB1, and CDKD1) and cyclins (CYCA3, CYCB1, and CYCD4), the main genes involved in the cell cycle and its regulation. Radicle tips of embryos were isolated from seeds placed for various times on water at 30 degrees C and from grains partially hydrated at moisture contents ranging from 11% to 51% fresh weight (FW), which prevent radicle elongation. Abscisic acid (ABA) contents of the embryos during seed germination at 30 degrees C and after 48 h of partial hydration were also measured. In dry embryos, cells are mostly arrested in the G(1) phase of the cell cycle (82%), the remaining cells being in the G(2) phase, and the ABA content of the embryo was 432.7 ng g(-1) dry weight (DW). Seed imbibition was associated with a sharp decrease in ABA content as early as 5 h, while the cell cycle reactivation was a late process taking place approximately 4-6 h prior to radicle protrusion. Hydration of seeds resulted in a decrease in embryo ABA content, but it remained at a high level (207-273 ng g(-1) DW) even after 48 h at 0.41-0.51 g H2O g(-1) FW. The cell population of the radicle tips in the G(2) phase of the cell cycle, i.e. 4C nuclei, increased from 9% up to 34% at a moisture content of 51% FW. In dry seeds, CDKA1 and CDKD1 mRNAs were present at low levels, but transcripts of CDKB1, CYCA3, CYCB1, and CYCD4 were not detected. Radicle

  1. 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

  2. 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.

  3. 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…

  4. 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

  5. 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.

  6. Is the peptide bond formation activated by Cu(2+) interactions? Insights from density functional calculations.

    PubMed

    Rimola, A; Rodríguez-Santiago, L; Ugliengo, P; Sodupe, M

    2007-05-24

    The catalytic role that Cu(2+) cations play in the peptide bond formation has been addressed by means of density functional calculations. First, the Cu(2+)-(glycine)2 --> Cu(2+)-(glycylglycine) + H2O reaction was investigated since mass spectrometry low collision activated dissociation (CAD) spectra of Cu(2+)-(glycine)2 led to the elimination of a water molecule, which suggested that an intracomplex peptide bond formation might have occurred. Results show that this intracomplex condensation is associated to a very high free energy barrier (97 kcal mol(-1)) and reaction free energy (66 kcal mol(-1)) because of the loss of metal coordination during the reaction. Second, on the basis of the salt-induced peptide formation theory, the condensation reaction between two glycines was studied in aqueous solution using discrete water molecules and the conductor polarized continuum model (CPCM) continuous method. It is found that the synergy between the interaction of glycines with Cu(2+) and the presence of water molecules acting as proton-transfer helpers significantly lower the activation barrier (from 55 kcal/mol for the uncatalyzed system to 20 kcal/mol for the Cu(2+) solvated system) which largely favors the formation of the peptide bond.

  7. Absolute Power Spectral Density Changes in the Magnetoencephalographic Activity During the Transition from Childhood to Adulthood.

    PubMed

    Gómez, Carlos M; Rodríguez-Martínez, Elena I; Fernández, Alberto; Maestú, Fernando; Poza, Jesús; Gómez, Carlos

    2017-01-01

    The aim of this study was to define the pattern of reduction in absolute power spectral density (PSD) of magnetoencephalography (MEG) signals throughout development. Specifically, we wanted to explore whether the human skull's high permeability for electromagnetic fields would allow us to question whether the pattern of absolute PSD reduction observed in the human electroencephalogram is due to an increase in the skull's resistive properties with age. Furthermore, the topography of the MEG signals during maturation was explored, providing additional insights about the areas and brain rhythms related to late maturation in the human brain. To attain these goals, spontaneous MEG activity was recorded from 148 sensors in a sample of 59 subjects divided into three age groups: children/adolescents (7-14 years), young adults (17-20 years) and adults (21-26 years). Statistical testing was carried out by means of an analysis of variance (ANOVA), with "age group" as between-subject factor and "sensor group" as within-subject factor. Additionally, correlations of absolute PSD with age were computed to assess the influence of age on the spectral content of MEG signals. Results showed a broadband PSD decrease in frontal areas, which suggests the late maturation of this region, but also a mild increase in high frequency PSD with age in posterior areas. These findings suggest that the intensity of the neural sources during spontaneous brain activity decreases with age, which may be related to synaptic pruning.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Fmrp Interacts with Adar and Regulates RNA Editing, Synaptic Density and Locomotor Activity in Zebrafish

    PubMed Central

    Porath, Hagit T.; Barak, Michal; Pinto, Yishay; Wachtel, Chaim; Zilberberg, Alona; Lerer-Goldshtein, Tali; Efroni, Sol; Levanon, Erez Y.; Appelbaum, Lior

    2015-01-01

    Fragile X syndrome (FXS) is the most frequent inherited form of mental retardation. The cause for this X-linked disorder is the silencing of the fragile X mental retardation 1 (fmr1) gene and the absence of the fragile X mental retardation protein (Fmrp). The RNA-binding protein Fmrp represses protein translation, particularly in synapses. In Drosophila, Fmrp interacts with the adenosine deaminase acting on RNA (Adar) enzymes. Adar enzymes convert adenosine to inosine (A-to-I) and modify the sequence of RNA transcripts. Utilizing the fmr1 zebrafish mutant (fmr1-/-), we studied Fmrp-dependent neuronal circuit formation, behavior, and Adar-mediated RNA editing. By combining behavior analyses and live imaging of single axons and synapses, we showed hyperlocomotor activity, as well as increased axonal branching and synaptic density, in fmr1-/- larvae. We identified thousands of clustered RNA editing sites in the zebrafish transcriptome and showed that Fmrp biochemically interacts with the Adar2a protein. The expression levels of the adar genes and Adar2 protein increased in fmr1-/- zebrafish. Microfluidic-based multiplex PCR coupled with deep sequencing showed a mild increase in A-to-I RNA editing levels in evolutionarily conserved neuronal and synaptic Adar-targets in fmr1-/- larvae. These findings suggest that loss of Fmrp results in increased Adar-mediated RNA editing activity on target-specific RNAs, which, in turn, might alter neuronal circuit formation and behavior in FXS. PMID:26637167

  13. Affects of mining activities on Cd pollution to the paddy soils and rice grain in Hunan province, Central South China.

    PubMed

    Du, Yan; Hu, Xue-Feng; Wu, Xiao-Hong; Shu, Ying; Jiang, Ying; Yan, Xiao-Juan

    2013-12-01

    Located in Central South China, Hunan province is rich in mineral resources. To study the influence of mining on Cd pollution to local agricultural eco-system, the paddy soils and rice grain of Y county in northern Hunan province were intensively monitored. The results were as follows: (1) Total Cd (T-Cd) content in the soils of the county ranges from 0.13 to 6.02 mg kg(-1), with a mean of 0.64 mg kg(-1), of which 57.5% exceed the allowable limit specified by the China Soil Environmental Quality Standards. T-Cd in the soils varies largely, with the coefficient of variation reaching 146.4%. The spatial distribution of T-Cd in the soils quite matches with that of mining and industries. The content of HCl-extractable Cd (HCl-Cd) in the soils ranges from 0.02 to 2.17 mg kg(-1), with a mean of 0.24 mg kg(-1). A significant positive correlation exists between T-Cd and HCl-Cd in the soils (r = 0.770, ρ < 0.01). (2) Cd content in the rice produced in Y county ranges from 0.01 to 2.77 mg kg(-1), with a mean of 0.46 mg kg(-1). The rate of rice with Cd exceeding the allowable limit specified by the Chinese Grain Security Standards reaches 59.6%; that with Cd exceeding 1 mg kg(-1), called as "Cd rice," reaches 11.1%. (3) Cd content in the rice of Y county is positively significantly correlated with HCl-Cd (r = 0.177, ρ < 0.05) but not significantly with T-Cd in the soils (r = 0.091, ρ > 0.05), which suggests that the amount of Cd accumulating in the rice is more affected by its availability in the soils, rather than the total content. (4) The dietary intake of Cd via rice consumption in Y county is estimated to be 179.9 μg day(-1) person(-1) on average, which is far beyond the allowable limit specified by FAO/WHO and the target hazard quotients of Cd much higher than 1, suggesting the high risk on human health from Cd exposure.

  14. Factors determining accumulation of mycotoxin producers in cereal grain during harvesting.

    PubMed

    Lugauskas, Albinas; Raila, Algirdas; Zvicevicius, Egidijus; Railiene, Marija; Novosinskas, Henrikas

    2007-01-01

    During the meteorologically contrasting period of 2003-2005, the contamination of winter wheat, malt barley and fodder barley grain with micromycetes during grain harvesting and preparation for storage was investigated. Micromycetes of over 70 species ascribed to 16 genera were isolated and identified, the density of their populations in grain was determined. Micromycetes with a population density of >50% were attributed to dominant species. Short biological characteristic, ecological peculiarities of the dominating micromycetes are provided; factors determining intensity of their development and abilities to synthesise and excrete toxic metabolites are indicated. The importance of grain drying for stabilisation of its contamination with micromycete propagules is highlighted. It is noted that in grain dried in shaft dryer using air at 90 degrees C the number of cfu (colony forming units) was reduced from 2.2 to 8.2 times. When active ventilation is applied, conditions favourable for the development of micromycetes remain longest in the upper layers of the mound. The airflow passing through the layer of damp grain inhibits the development of micromycetes, but an increase of comparative air flow for more than 500 m3x(txh)(-1) did not reduce the abundance of micromycete cfu. After drying Alternaria alternata, Fusarium avenaceum, F. culmorum, Penicillum verrucosum dominated in wheat grain; Aspergillus flavus, Bipolaris sorokiniana, Fusarium chlamydosporum, F. culmorum, F. tricinctum in malts barley grain; Fusarium avenaceum, F. culmorum, F. tricinctum, Alternaria alternata in fodder barley grain. It has been determined that all micromycetes recorded on grain after drying are potential producers of toxic metabolites, i.e. are hazardous to human health.

  15. Nano-XRF Analysis of Metal Impurities Distribution at PL Active Grain Boundaries During mc-Silicon Solar Cell Processing

    SciTech Connect

    Bernardini, Simone; Johnston, Steve; West, Bradley; Naerland, Tine U.; Stuckelberger, Michael; Lai, Barry; Bertoni, Mariana I.

    2017-01-01

    Metal impurities are known to hinder the performance of commercial Si-based solar cells by inducing bulk recombination, increasing leakage current, and causing direct shunting. Recently, a set of photoluminescence (PL) images of neighboring multicrystalline silicon wafers taken from a cell production line at different processing stages has been acquired. Both band-to-band PL and sub-bandgap PL (subPL) images showed various regions with different PL signal intensity. Interestingly, in several of these regions a reversal of the subPL intensity was observed right after the deposition of the antireflective coating. In this paper, we present the results of the synchrotron-based nano-X-ray fluorescence imaging performed in areas characterized by the subPL reversal to evaluate the possible role of metal decoration in this uncommon behavior. Furthermore, the acquisition of a statistically meaningful set of data for samples taken at different stages of the solar cell manufacturing allows us to shine a light on the precipitation and rediffusion mechanisms of metal impurities at these grain boundaries.

  16. Methylcholine-activated eccrine sweat gland density and output as a function of age.

    PubMed

    Kenney, W L; Fowler, S R

    1988-09-01

    The purpose of this investigation was to examine eccrine sweat gland responsiveness to intradermal injections of methylcholine (MCh) across three age groups of men [young (Y) = 22-24; middle (M) = 33-40; older (O) = 58-67 yr old, n = 5 per group]. Subjects were matched with respect to maximum O2 consumption, body size, and body composition, and were thoroughly heat acclimated before participation. Randomly ordered concentrations of acetyl-beta-methylcholine chloride ranging from 0% (saline) to 0.1% (5 x 10(-3) M) were injected into the skin of the dorsal thigh in a thermoneutral environment, and activated sweat glands were photographed at 30-s intervals for the next 8 min. Density of MCh-activated glands was independent of both age and [MCh] (e.g., 2 min after injection of 5 x 10(-3) M [MCh]: Y = 45 +/- 7, M = 46 +/- 12, O = 42 +/- 5 glands/cm2). However, sweat gland output (SGO) per active gland was significantly lower for the O group and failed to increase with increasing [MCh] above 5 x 10(-4) M. When MCh (5 x 10(-3) M) was injected after 1 h of exercise in the heat, higher SGO's were elicited in each group; however, the SGO of the O group was again significantly lower than that of the Y group (91 +/- 11 vs. 39 +/- 4 ng/gland, P less than 0.02) with the M group intermediate (69 +/- 11 nl/gland; 2 min postinjection data).(ABSTRACT TRUNCATED AT 250 WORDS)

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

    PubMed

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

    2013-01-07

    Ceria (CeO(2)) is a promising catalyst for the reduction of carbon dioxide (CO(2)) to liquid fuels and commodity chemicals, in part because of its high oxygen storage capacity, yet the fundamentals of CO(2) 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 CO(2) on stoichiometric and reduced ceria (110), the latter with either an in-plane oxygen vacancy or a split oxygen vacancy. We find that CO(2) 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 CO(2) adsorbed parallel to the reduced ceria (110) surface at a split oxygen vacancy. Structural changes in the CO(2) 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 CO(2) adsorption at the in-plane vacancy. Also, we analyze the pathways for CO(2) conversion to CO on reduced ceria (110). The subtle difference in the energies of activation for the elementary steps suggest that CO(2) 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 CO(2) activation and reduction.

  18. Defect recombination induced by density-activated carrier diffusion in nonpolar InGaN quantum wells

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Zhang, Chunfeng; Shi, Chentian; Joo Park, Min; Seop Kwak, Joon; Jung, Sukkoo; Choi, Yoon-Ho; Wu, Xuewei; Wang, Xiaoyong; Xiao, Min

    2013-09-01

    We report on the observation of carrier-diffusion-induced defect emission at high excitation density in a-plane InGaN single quantum wells. When increasing excitation density in a relatively high regime, we observed the emergence of defect-related emission together with a significant efficiency reduction of bandedge emission. The experimental results can be well explained with the density-activated carrier diffusion from localized states to defect states. Such a scenario of density-activated defect recombination, as confirmed by the dependences of photoluminescence on the excitation photon energy and temperature, is a plausible origin of efficiency droop in a-plane InGaN quantum-well light-emitting diodes.

  19. Application of hybrid supercapacitor using granule Li4Ti5O12/activated carbon with variation of current density

    NASA Astrophysics Data System (ADS)

    Lee, Byung-Gwan; Lee, Seung-Hwan

    2017-03-01

    We report the electrochemical performance of asymmetric hybrid supercapacitors composed of granule Li4Ti5O12 as an anode and activated carbon as a cathode with different current densities. It is demonstrated that the hybrid supercapacitors show good initial discharge capacities were ranged from 39.8 to 46.4 F g-1 in the current densities range of 0.3-1 A g-1. The performance degradation is proportional to the current density due to quick gassing, resulting from H2O and HF formation. In particular, the hybrid supercapacitors show the pretty good cycling stability of 97.4%, even at the high current density of 0.8 A g-1, which are among most important performance in the real application for energy storage devices. Therefore, we believe that hybrid supercapacitors using granule Li4Ti5O12/activated carbon are eligible for the promising next generation energy devices.

  20. 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.

  1. 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…

  2. 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.

  3. 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.

  4. Insecticidal activity of essential oil of Carum Carvi fruits from China and its main components against two grain storage insects.

    PubMed

    Fang, Rui; Jiang, Cai Hong; Wang, Xiu Yi; Zhang, Hai Ming; Liu, Zhi Long; Zhou, Ligang; Du, Shu Shan; Deng, Zhi Wei

    2010-12-20

    During our screening program for agrochemicals from Chinese medicinal herbs and wild plants, the essential oil of Carum carvi fruits was found to possess strong contact toxicity against Sitophilus zeamais and Tribolium castaneum adults, with LD₅₀ values of 3.07 and 3.29 μg/adult, respectively, and also showed strong fumigant toxicity against the two grain storage insects with LC₅₀ values of 3.37 and 2.53 mg/L, respectively. The essential oil obtained by hydrodistillation was investigated by GC and GC-MS. The main components of the essential oil were identified to be (R)-carvone (37.98%) and D-limonene (26.55%) followed by α-pinene (5.21), cis-carveol (5.01%) and β-myrcene (4.67%). (R)-Carvone and D-limonene were separated and purified by silica gel column chromatography and preparative thin layer chromatography, and further identified by means of physicochemical and spectrometric analysis. (R)-Carvone and D-limonene showed strong contact toxicity against S. zeamais (LD₅₀ = 2.79 and 29.86 μg/adult) and T. castaneum (LD₅₀ = 2.64 and 20.14 μg/adult). (R)-Carvone and D-limonene also possessed strong fumigant toxicity against S. zeamais (LC₅₀ = 2.76 and 48.18 mg/L) and T. castaneum adults (LC₅₀ = 1.96 and 19.10 mg/L).

  5. 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.

  6. Oxidized low density lipoprotein increases acetylcholinesterase activity correlating with reactive oxygen species production.

    PubMed

    Yamchuen, Panit; Aimjongjun, Sathid; Limpeanchob, Nanteetip

    2014-12-01

    Hyperlipidemia, low density lipoproteins (LDL) and their oxidized forms, and oxidative stress are suspected to be a key combination in the onset of AD and acetylcholinesterase (AChE) plays a part in this pathology. The present study aimed to link these parameters using differentiated SH-SY5Y human neuroblastoma cells in culture. Both mildly and fully oxidized human LDL (mox- and fox-LDL), but not native (non-oxidized) LDL were cytotoxic in dose- and time-dependent patterns and this was accompanied by an increased production of intracellular reactive oxygen species (ROS). Oxidized LDL (10-200 μg/mL) augmented AChE activity after 4 and 24h treatments, respectively while the native LDL was without effect. The increased AChE with oxidized LDLs was accompanied by a proportionate increase in intracellular ROS formation (R=0.904). These findings support the notion that oxidized LDLs are cytotoxic and that their action on AChE may reduce central cholinergic transmission in AD and affirm AChE as a continued rational for anticholinesterase therapy but in conjunction with antioxidant/antihyperlipidemic cotreatments.

  7. 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.

  8. 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.

  9. Strain energy density gradients in bone marrow predict osteoblast and osteoclast activity: a finite element study.

    PubMed

    Webster, Duncan; Schulte, Friederike A; Lambers, Floor M; Kuhn, Gisela; Müller, Ralph

    2015-03-18

    Huiskes et al. hypothesized that mechanical strains sensed by osteocytes residing in trabecular bone dictate the magnitude of load-induced bone formation. More recently, the mechanical environment in bone marrow has also been implicated in bone׳s response to mechanical stimulation. In this study, we hypothesize that trabecular load-induced bone formation can be predicted by mechanical signals derived from an integrative µFE model, incorporating a description of both the bone and marrow phase. Using the mouse tail loading model in combination with in vivo micro-computed tomography (µCT) we tracked load induced changes in the sixth caudal vertebrae of C57BL/6 mice to quantify the amount of newly mineralized and eroded bone volumes. To identify the mechanical signals responsible for adaptation, local morphometric changes were compared to micro-finite element (µFE) models of vertebrae prior to loading. The mechanical parameters calculated were strain energy density (SED) on trabeculae at bone forming and resorbing surfaces, SED in the marrow at the boundary between bone forming and resorbing surfaces, along with SED in the trabecular bone and marrow volumes. The gradients of each parameter were also calculated. Simple regression analysis showed mean SED gradients in the trabecular bone matrix to significantly correlate with newly mineralized and eroded bone volumes R(2)=0.57 and 0.41, respectively, p<0.001). Nevertheless, SED gradients in the marrow were shown to be the best predictor of osteoblastic and osteoclastic activity (R(2)=0.83 and 0.60, respectively, p<0.001). These data suggest that the mechanical environment of the bone marrow plays a significant role in determining osteoblast and osteoclast activity.

  10. 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.

  11. Density, activity, and diversity of bacteria indigenous to a karstic aquifer.

    PubMed

    Rusterholtz, K J; Mallory, L M

    1994-07-01

    The microbial ecology of karstic ground water is largely unknown. The density, activity, and diversity of bacteria indigenous to subsurface karstic material in Mammoth Cave National Park, Mammoth Cave, Kentucky were studied using minimally disruptive, on-site procedures. Two sites, located 100 m below the surface and consisting of saturated fine to coarse sand in pooled water, were examined. Samples were taken aseptically using modified, sterile 60-cc syringes. Total cell and total respiring cell densities were determined using an acridine orange/p-iodonitrotetrazolium violet (AO/INT) staining procedure. Cells in selected cores were stained with INT and incubated in the cave for 4 h prior to fixing with glutaraldehyde and subsequent transport to the laboratory. Cells were stained with AO in the laboratory. Low- and high-nutrient media were used to determine viable cell counts. Plates were incubated in the cave for 1 day at ambient temperature prior to transportation to the laboratory in an insulated cooler. Viable cell counts ranged from 1.0 × 106 to 8.1 × 106 cells wet g(-1) of sediment. Total direct counts were 3.9 × 106 and 1.4 × 107 cells wet g(-1) for the Olivia's Dome and the Catherine's Dome sites, respectively. Viable cell counts were highly similar to respiring cell counts at both sites. At the Olivia's Dome site, viable cell counts represented 26-31% of the direct cell counts, while 58% of the total cell count were actively respiring. At the Catherine's Dome site, viable cell counts represented 11-58% of the direct counts, while 53% of the cells were actively respiring. A total of 237 strains recovered from low- and high-nutrient media at both Olivia's and Catherine's Domes, and 10 reference strains were examined for 117 morphological, biochemical, and physiological characteristics. Results were coded in a binary fashion and analyzed using numerical taxonomic techniques. Similarity values were calculated using a simple matching coefficient. Fifty

  12. 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.

  13. Growth model and metabolic activity of brewing yeast biofilm on the surface of spent grains: a biocatalyst for continuous beer fermentation.

    PubMed

    Brányik, Tomás; Vicente, António A; Kuncová, Gabriela; Podrazký, Ondrej; Dostálek, Pavel; Teixeira, José A

    2004-01-01

    In the continuous systems, such as continuous beer fermentation, immobilized cells are kept inside the bioreactor for long periods of time. Thus an important factor in the design and performance of the immobilized yeast reactor is immobilized cell viability and physiology. Both the decreasing specific glucose consumption rate (q(im)) and intracellular redox potential of the cells immobilized to spent grains during continuous cultivation in bubble-column reactor implied alterations in cell physiology. It was hypothesized that the changes of the physiological state of the immobilized brewing yeast were due to the aging process to which the immobilized yeast are exposed in the continuous reactor. The amount of an actively growing fraction (X(im)act) of the total immobilized biomass (X(im)) was subsequently estimated at approximately X(im)act = 0.12 g(IB) g(C)(-1) (IB = dry immobilized biomass, C = dry carrier). A mathematical model of the immobilized yeast biofilm growth on the surface of spent grain particles based on cell deposition (cell-to-carrier adhesion and cell-to-cell attachment), immobilized cell growth, and immobilized biomass detachment (cell outgrowth, biofilm abrasion) was formulated. The concept of the active fraction of immobilized biomass (X(im)act) and the maximum attainable biomass load (X(im)max) was included into the model. Since the average biofilm thickness was estimated at ca. 10 microm, the limitation of the diffusion of substrates inside the yeast biofilm could be neglected. The model successfully predicted the dynamics of the immobilized cell growth, maximum biomass load, free cell growth, and glucose consumption under constant hydrodynamic conditions in a bubble-column reactor. Good agreement between model simulations and experimental data was achieved.

  14. 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.

  15. Electrical conduction of intrinsic grain and grain boundary in Mn-Co-Ni-O thin film thermistors: Grain size influence

    NASA Astrophysics Data System (ADS)

    He, L.; Ling, Z. Y.

    2011-11-01

    Mn1.85Co0.3Ni0.85O4 (MCN) thin films with pure spinel phase and different grain size were prepared on Al2O3 substrates by chemical deposition method. Temperature dependent ac impedance spectroscopy was employed to analyze the grain size influence on the electrical conduction of intrinsic grain and grain boundary (GB) in MCN thin films. The conduction mechanisms of grain and GB both followed the small-polaron hopping model. It was found that the hopping types of GB (nearest-neighbor-hopping (NNH)) and grain (a transition from variable-range-hopping (VRH) to NNH) were not affected by the grain size, while the resistance, characteristic temperature, and activation energy of grain and GB were affected by the grain size in varying degrees. Additionally, the mechanisms concerning the dependence of electrical conduction of grain and GB on the grain size of MCN thin films were discussed in detail. These studies will also provide a comprehensive understanding of the conduction behaviors of a system with mixed NNH and VRH.

  16. 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)

  17. The impact of helium on thermosphere mass density response to geomagnetic activity during the recent solar minimum

    NASA Astrophysics Data System (ADS)

    Thayer, J. P.; Liu, X.; Lei, J.; Pilinski, M.; Burns, A. G.

    2012-07-01

    High-resolution mass density observations inferred from accelerometer measurements on the CHAMP and GRACE satellites are employed to investigate the thermosphere mass density response with latitude and altitude to geomagnetic activity during the recent solar minimum. Coplanar orbital periods in February 2007 and December 2008 revealed the altitude and latitude response in thermosphere mass density for their respective winter hemispheres was influenced by the relative amount of helium and oxygen present. The CHAMP-to-GRACE (C/G) mass density ratio depends on two terms; the first proportional to the ratio of the mean molecular weight to temperature and the second proportional to the vertical gradient of the logarithmic mean molecular weight. For the relative levels of helium and oxygen in February 2007, the winter hemisphere C/G mass density response to geomagnetic activity, although similar to the summer hemisphere, was caused predominantly by changes in the vertical gradient of the logarithmic mean molecular weight. In December 2008, the significant presence of helium caused the mean molecular weight changes to exceed temperature changes in the winter hemisphere leading to an increase in the C/G ratio with increasing geomagnetic activity, in opposition to the decrease observed in the summer hemisphere that was caused primarily by temperature changes. The observed behavior is indicative of composition effects influencing the mass density response and the dynamic action of the oxygen to helium transition region in both latitude and altitude will lead to complex behaviors in the mass density at GRACE altitudes throughout the extended solar minimum from 2007 to 2010.

  18. Reversal in the Size Dependence of Grain Rotation

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoling; Tamura, Nobumichi; Mi, Zhongying; Lei, Jialin; Yan, Jinyuan; Zhang, Lingkong; Deng, Wen; Ke, Feng; Yue, Binbin; Chen, Bin

    2017-03-01

    The conventional belief, based on the Read-Shockley model for the grain rotation mechanism, has been that smaller grains rotate more under stress due to the motion of grain boundary dislocations. However, in our high-pressure synchrotron Laue x-ray microdiffraction experiments, 70 nm nickel particles are found to rotate more than any other grain size. We infer that the reversal in the size dependence of the grain rotation arises from the crossover between the grain boundary dislocation-mediated and grain interior dislocation-mediated deformation mechanisms. The dislocation activities in the grain interiors are evidenced by the deformation texture of nickel nanocrystals. This new finding reshapes our view on the mechanism of grain rotation and helps us to better understand the plastic deformation of nanomaterials, particularly of the competing effects of grain boundary and grain interior dislocations.

  19. 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

  20. [Low density lipoprotein rich in triglycerides and hepatic lipase activity in insulin-dependent diabetic patients].

    PubMed

    Rosental, S B; Schreier, L E; Halperin, H; Berg, G; Paglione, A M; Ruiz, M; Wikinski, R L

    1995-01-01

    Genetic hepatic lipase (HL) deficiency is associated with low density lipoprotein (LDL) rich in triglycerides (TG), whose affinity for B:E receptors is decreased. In rats, experimental hypoinsulinemia produces HL deficiency. However, the relation between human insulin-dependent Diabetes Mellitus (IDDM), HL activity and the characteristics of LDL have not been studied. The objective of our study is to evaluate the relation between HL activity and the chemical composition of LDL in treated IDDM patients. Subjects were 15 IDDM patients and 15 controls (C), matched for sex and body mass index (BMI). The IDDM patients were classified by the WHO criteria, were free of nephropathy and hypothyroidism, and received no medication except insulin. Controls were clinically healthy and normolipidemic with no family history of diabetes. The IDDM group was divided into two subgroups: subgroup IDDM-A (n = 9) with HL values > or = 4.3 and IDDM-B (n = 6) with HL < or = than 4.2 mumoles glycerol/ml h. the HL in IDDM was lower than in C (p < 0.001). Table 1 shows clinical data. Blood samples were drawn after 12 h fasting. Percentage of HbA1c and plasma concentrations of glucose, total cholesterol, LDL-cholesterol, HDL-cholesterol and TG were assayed. LDL was separated by sequential ultracentrifugation at densities of 1.019-1.063 g/ml and its chemical composition was analyzed. The most relevant results were: plasma TG concentration was higher in IDDM than in C (p < 0.05) (Table 2), although average values DMID not exceed the reference values of 200 mg/dl. The TG-LDL were higher in IDDM than in C: 24.8 +/- 2.7 vs 17.5 +/- 1.1 mg/dl plasma, media +/- SE, (p < 0.02). This difference reflected the values of IDDM-B, whose plasma concentrations of TG-LDL were higher than in C: 32.3 +/- 3.6 vs 17.5 +/- 1.1 mg/dl (p < 0.001), and also higher than in IDDM-A (p < 0.02). (Table 3). The chemical composition of LDL in IDDM-B contained a higher percentage of TG than C: 8.5 +/- 0.7 vs 6.8 +/- 0.3% (p

  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. 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.

  3. 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…

  4. 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…

  5. Comparative analysis of dose rates in bricks determined by neutron activation analysis, alpha counting and X-ray fluorescence analysis for the thermoluminescence fine grain dating method

    NASA Astrophysics Data System (ADS)

    Bártová, H.; Kučera, J.; Musílek, L.; Trojek, T.

    2014-11-01

    In order to evaluate the age from the equivalent dose and to obtain an optimized and efficient procedure for thermoluminescence (TL) dating, it is necessary to obtain the values of both the internal and the external dose rates from dated samples and from their environment. The measurements described and compared in this paper refer to bricks from historic buildings and a fine-grain dating method. The external doses are therefore negligible, if the samples are taken from a sufficient depth in the wall. However, both the alpha dose rate and the beta and gamma dose rates must be taken into account in the internal dose. The internal dose rate to fine-grain samples is caused by the concentrations of natural radionuclides 238U, 235U, 232Th and members of their decay chains, and by 40K concentrations. Various methods can be used for determining trace concentrations of these natural radionuclides and their contributions to the dose rate. The dose rate fraction from 238U and 232Th can be calculated, e.g., from the alpha count rate, or from the concentrations of 238U and 232Th, measured by neutron activation analysis (NAA). The dose rate fraction from 40K can be calculated from the concentration of potassium measured, e.g., by X-ray fluorescence analysis (XRF) or by NAA. Alpha counting and XRF are relatively simple and are accessible for an ordinary laboratory. NAA can be considered as a more accurate method, but it is more demanding regarding time and costs, since it needs a nuclear reactor as a neutron source. A comparison of these methods allows us to decide whether the time- and cost-saving simpler techniques introduce uncertainty that is still acceptable.

  6. Effect of long-term unilateral activity on bone mineral density of female junior tennis players.

    PubMed

    Haapasalo, H; Kannus, P; Sievänen, H; Pasanen, M; Uusi-Rasi, K; Heinonen, A; Oja, P; Vuori, I

    1998-02-01

    distal radius), no significant BMD differences were found between the players and controls in any Tanner stage. In the correlation analysis, the Tanner I and II players (mean ages 9.4 and 10.8 years) showed no significant associations between any of the predictive variables and the side-to-side BMD differences, while in Tanner stages III, IV, and V, such associations could be found; the total amount of training hours during the playing career and the number of training sessions per week showed a significant and systematic correlation (rs ranging from 0.43 to 0.80) with the side-to-side BMD differences in several measured bone sites. In conclusion, this study suggests that in a majority of female junior tennis players, the benefit of unilateral activity on bone density does not become clearly evident until the adolescent growth spurt or Tanner stage III. The total amount of training during the player's career and the current training frequency (sessions per week) seem to best explain the training effect on bone tissue, leaving, however, room for speculation on the still unknown factors that modulate the loading response of a growing bone.

  7. Antifungal activity of essential oil of Ziziphora clinopodioides and the inhibition of aflatoxin B1 production in maize grain.

    PubMed

    Moghadam, Hediyeh Davoudi; Sani, Ali Mohamadi; Sangatash, Masoomeh Mehraban

    2016-03-01

    The aim of this study was to determine the antifungal effect of the essential oil obtained from Ziziphora clinopodioides L on two fungi species including Aspergillus flavus and Aspergillus parasiticus using microdilution method. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined for the essential oil at 10 different concentrations (i.e. 25,000, 12,500, 6250, 3125, 1562.5, 781.25, 390.625, 195.31, 97.65, and 48.82 µg/ml). Finally, the effect of the essential oil at six levels (6250, 3125, 1600, 800, 400, and 196 µg/ml) was investigated on the growth and activity of A. flavus and A. parasiticus, and also toxin production of these species in maize at 0.97 aw and 25°C after 29 days. Aflatoxin B1 (AFB1) content was assayed by enzyme linked immuno-sorbent assay technique. Results showed that essential oil of Z. clinopodioides was found more effective on A. parasiticus than A. flavus in both in vitro and in vivo conditions. Z. clinopodioides oil exhibited the same MIC value in the liquid medium against all fungal strains (48.82 µg/ml), while it showed different activity against A. flavus and A. parasiticus with MFC values of 781.25 and 390.625 µg/ml respectively. Under storage condition in maize, AFB1 production was significantly (p < 0.05) repressed at the concentration of 6250 µg/ml for A. flavus and 6250 and 3125 µg/ml for A. parasiticus. At the lower concentrations, the AFB1 production increased gradually. The results of the present study indicated that the essential oil of Z. clinopodioides had significant antifungal activity (p < 0.05); therefore, it can be used as an antifungal agent in the food and medicinal industries.

  8. Spatial distribution of allochthonous fine-grained sediments from drilling activities in the deepwater Ulleung Basin, Korea

    NASA Astrophysics Data System (ADS)

    Chun, Jong-Hwa; Um, In-Kwon; Bahk, Jang-Jun; Kim, Yuri; Ryu, Byong-Jae

    2015-04-01

    The marine sediments in deepwater basins can be used as sedimentologic, stratigraphic, paleoceanographic, and paleoclimatologic tools to interpret the various scientific topics in the world. As a result, many drilling and coring activities were performed by international ocean drilling programs in deepwater basins during the last 50 years. In the deepwater Ulleung Basin, the Second Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2) was conducted to perform the gas hydrate R&D in 2010. During the UBGH2, drilling and coring activities were successfully accomplished in 13 sites ranging from 898 m to 2,156 m water depth. The three major sediment facies in the Ulleung Basin are composed of light-colored bioturbated hemipelagic muds under a highly oxygenated bottom-water conditions, dark-colored crudely laminated muds under a poorly oxygenated bottom-water conditions, and laminated/massive sand with turbidites. The present seafloor sediments commonly consist of 1-2 thick light-colored bioturbated hemipelagic muds in the deepwater Ulleung Basin. We observed the UBGH2 drilling holes using by Ultra-short Baseline (USBL)-guided KIGAM Seafloor Observation System (KISOS) in 2013. The UBGH2 drilling holes were found on the seafloor with partially collapse of the margin. We also found the multi-colored sediment patches on the seafloor due to allochthonous sediment input. We analyzed the elements using a non-destructive Itrax X-ray fluorescence (XRF) core scanner for split core. The sediment patches have relatively low concentrations of Fe, Ba, Mn and Pb compared to the element concentrations of the present seafloor sediments. The concentrations of K, Ca, and Ti are higher than the present seafloor sediments. The patch sediments are observed no more than 50 m away from the UBGH2 drilling holes. The allochthonous sediments occur at depth of about 6 cm below seafloor in the observed drilling holes. The origin of allochthonous sediments on the seafloor is interpreted as drilling

  9. 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.

  10. 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.

  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. 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.

  13. Osmoregulation in Lilium pollen grains occurs via modulation of the plasma membrane H+ ATPase activity by 14-3-3 proteins.

    PubMed

    Pertl, Heidi; Pöckl, Magdalena; Blaschke, Christian; Obermeyer, Gerhard

    2010-12-01

    To allow successful germination and growth of a pollen tube, mature and dehydrated pollen grains (PGs) take up water and have to adjust their turgor pressure according to the water potential of the surrounding stigma surface. The turgor pressure of PGs of lily (Lilium longiflorum) was measured with a modified pressure probe for simultaneous recordings of turgor pressure and membrane potential to investigate the relation between water and electrogenic ion transport in osmoregulation. Upon hyperosmolar shock, the turgor pressure decreased, and the plasma membrane (PM) hyperpolarizes in parallel, whereas depolarization of the PM was observed with hypoosmolar treatment. An acidification and alkalinization of the external medium was monitored after hyper- and hypoosmotic treatments, respectively, and pH changes were blocked by vanadate, indicating a putative role of the PM H(+) ATPase. Indeed, an increase in PM-associated 14-3-3 proteins and an increase in PM H(+) ATPase activity were detected in PGs challenged by hyperosmolar medium. We therefore suggest that in PGs the PM H(+) ATPase via modulation of its activity by 14-3-3 proteins is involved in the regulation of turgor pressure.

  14. Osmoregulation in Lilium Pollen Grains Occurs via Modulation of the Plasma Membrane H+ ATPase Activity by 14-3-3 Proteins1[C][W][OA

    PubMed Central

    Pertl, Heidi; Pöckl, Magdalena; Blaschke, Christian; Obermeyer, Gerhard

    2010-01-01

    To allow successful germination and growth of a pollen tube, mature and dehydrated pollen grains (PGs) take up water and have to adjust their turgor pressure according to the water potential of the surrounding stigma surface. The turgor pressure of PGs of lily (Lilium longiflorum) was measured with a modified pressure probe for simultaneous recordings of turgor pressure and membrane potential to investigate the relation between water and electrogenic ion transport in osmoregulation. Upon hyperosmolar shock, the turgor pressure decreased, and the plasma membrane (PM) hyperpolarizes in parallel, whereas depolarization of the PM was observed with hypoosmolar treatment. An acidification and alkalinization of the external medium was monitored after hyper- and hypoosmotic treatments, respectively, and pH changes were blocked by vanadate, indicating a putative role of the PM H+ ATPase. Indeed, an increase in PM-associated 14-3-3 proteins and an increase in PM H+ ATPase activity were detected in PGs challenged by hyperosmolar medium. We therefore suggest that in PGs the PM H+ ATPase via modulation of its activity by 14-3-3 proteins is involved in the regulation of turgor pressure. PMID:20974894

  15. Activation of 15-lipoxygenase by low density lipoprotein in vascular endothelial cells. Relationship to the oxidative modification of low density lipoprotein.

    PubMed

    Derian, C K; Lewis, D F

    1992-01-01

    Oxidatively-modified low density lipoprotein (LDL) is thought to play a significant role in the formation of lipid-laden macrophages, the primary cellular component of atherosclerotic fatty lesions. Recently, lipoxygenases have been implicated as a major enzymatic pathway involved in rabbit endothelial cell-mediated LDL modification. We investigated the effect of LDL on porcine aortic endothelial cell (PAEC) and human umbilical vein (HUVEC) and aortic endothelial cell (HAEC) lipoxygenase activity. By thin layer chromatography, we observed that human LDL stimulated the metabolism of radiolabeled arachidonic acid to 12 + 15-hydroxyeicosatetraenoic acid (HETE) in indomethacin-treated PAEC. Furthermore, radiolabeled linoleic acid, a specific substrate for the 15-lipoxygenase, was metabolized to its respective product 13-hydroxyoctadecadienoic acid (13-HODE) in the presence of LDL. Increased product formation in both studies was inhibited by the lipoxygenase blockers nordihydroguaiaretic acid (NDGA) and RG 6866. 15-HETE was confirmed as the predominant HETE product in LDL-treated cells by high performance liquid chromatography. Both porcine- and human-derived LDL stimulated the CL release of 15-HETE from cells as determined by radioimmunoassay. Release of immunoreactive 15-HETE was inhibited by NDGA, RG 6866, and 5,8,11,14-eicosatetraynoic acid (ETYA) but not by the selective 5-lipoxygenase inhibitor RG 5901. These lipoxygenase inhibitors had similar effects on the modification of LDL. Our results suggest that the oxidative modification of LDL by endothelial cells may be mediated in part through activation of 15-lipoxygenase.

  16. Effect of Methionine Restriction on Bone Density and NK Cell Activity

    PubMed Central

    Dong, Jingming

    2016-01-01

    Methionine restriction (MR) is proven to increase the lifespan; and it also affects the bone density and the innate immune system. The aim of this study is to explore the effect of methionine restriction on bone density and natural killer (NK) cells. C57BL/6J mice were subjected to either basal diet (BD, containing 0.80% methionine) or methionine-restricted diet (containing 0.14% methionine). Mice with MR diet displayed reduced bone mass and decrease in the cytotoxicity of NK from the spleen, compared to BD animals. Also, mice with MR diet had an inferior body weight (P < 0.05) and higher plasma levels of adiponectin and FGF21 (P < 0.05) but lower concentrations of leptin and IGF-1 (P < 0.05). Overall, the investigation shows that methionine affects bone density and NK cell cytotoxicity. PMID:27882323

  17. Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds.

    PubMed

    Saska, P; van der Werf, W; de Vries, E; Westerman, P R

    2008-04-01

    Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a field.

  18. 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.

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

    DOE PAGES

    Dey, Sanchita; Mardinly, John; Wang, Yongqiang; ...

    2016-05-27

    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, in this study, we tested this concept in nanocrystalline zirconia doped with lanthanum. Although the dopant is observedmore » 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.« less

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

    SciTech Connect

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

    2016-05-27

    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, in this study, 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.

  1. 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.

  2. On the interaction of solutes with grain boundaries

    DOE PAGES

    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

  3. Grain-filling problem in 'super' rice.

    PubMed

    Yang, Jianchang; Zhang, Jianhua

    2010-01-01

    Modern rice (Oryza sativa L.) cultivars, especially the newly bred 'super' rice, have numerous spikelets on a panicle with a large yield capacity. However, these cultivars often fail to achieve their high yield potential due to poor grain-filling of later-flowering inferior spikelets (in contrast to the earlier-flowering superior spikelets). Conventional thinking to explain the poor grain-filling is the consequence of carbon limitation. Recent studies, however, have shown that carbohydrate supply should not be the major problem because they have adequate sucrose at their initial grain-filling stage. The low activities of key enzymes in carbon metabolism may contribute to the poor grain-filling. Proper field practices, such as moderate soil drying during mid- and late grain-filling stages, could solve some problems in poor grain-filling. Further studies are needed by molecular approaches to investigate the signal transport, the hormonal action, the gene expressions, and the biochemical processes in inferior spikelets.

  4. 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

  5. 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.

  6. 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.

  7. Solar Cycle Variations of the F Corona Brightness Resulting from the Interaction of Dust Grains with CMEs

    NASA Astrophysics Data System (ADS)

    Ragot, B.; Kahler, S.

    2002-12-01

    The density of interplanetary dust increases sunward to reach its maximum in the F corona, where its scattered white-light intensity dominates that of the electron K corona above about 4 Rs. We consider the effects of interactions between the dust and the particles and fields of coronal mass ejections (CMEs). The dominant forces, with and without CMEs, acting on the dust close to the Sun are calculated for dust grain radii ranging from 0.01 to 100 microns. Dust grain orbits are then computed to compare the drift rates from assumed grain injections at 5 Rs to lower orbits for periods of minimum and maximum solar activity, where a simple CME model is adopted to distinguish the two periods. The CMEs result in significantly shorter drift times of the large (> 3 microns) dust grains, hence faster depletion rates and lower dust grain densities, at solar maxima. This would explain a relatively strong (> 30%) solar cycle variation of the near infrared brightness close to the dust plane of symmetry. While trapping the smallest of the grains, the CMEs also help scatter in latitude the grains of intermediate size (0.1 to 3 microns). The consequences for the optical brightness should be a time variation correlated to the solar cycle, not to exceed 10% at high latitude with a better isotropy reached at solar maxima. Limits on the dust size spectra are set from the basic features of the optical and infrared brightness distributions and variations.

  8. Effects of Cooling Rate and Solute Content on the Grain Refinement of Mg-Gd-Y Alloys by Aluminum

    NASA Astrophysics Data System (ADS)

    Dai, Jichun; Easton, Mark A.; Zhang, Mingxing; Qiu, Dong; Xiong, Xiangyuan; Liu, Wencai; Wu, Guohua

    2014-09-01

    The effect of Al additions on grain refinement of Mg-Gd-Y alloys with different solute contents at different cooling rates has been investigated. For all alloys, significant grain refinement was due to the formation of Al2(Gd x Y1- x ) nucleant particles. The number density and size distribution of Al2(Gd x Y1- x ) were affected by both solute content and the cooling rate. Grain sizes ( d gs) of Mg-Gd-Y base alloys and of Mg-Gd-Y-Al alloys were related to solute content (defined by the growth restriction factor, Q), cooling rate (), and area number density ( ρ ns) and size ( d p) of nucleant particles that can be activated. It is found that grain sizes of Mg-Gd-Y base alloys follow the relationship , while grain sizes of Al-refined samples follow the relationship , where a, b, a', and b' were constants. In addition, the grain refinement effect of Al additions was more susceptible to solute content and the cooling rate than that of Zr which is regarded as the most efficient grain refiner for Mg alloys.

  9. 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

    2013-10-21

    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.

  10. 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

  11. Modeling of complex antibody elution behavior under high protein load densities in ion exchange chromatography using an asymmetric activity coefficient.

    PubMed

    Huuk, Thiemo C; Hahn, Tobias; Doninger, Katharina; Griesbach, Jan; Hepbildikler, Stefan; Hubbuch, Jürgen

    2017-03-01

    A main requirement for the implementation of model-based process development in industry is the capability of the model to predict high protein load densities. The frequently used steric mass action isotherm assumes a thermodynamically ideal system and, hence constant activity coefficients. In this manuscript, an industrial antibody purification problem under high load conditions is considered where this assumption does not hold. The high protein load densities, as commonly applied in industrial downstream processing, may lead to complex elution peak shapes. Using Mollerup's generalized ion-exchange isotherm (GIEX), the observed elution peak shapes could be modeled. To this end, the GIEX isotherm introduced two additional parameters to approximate the asymmetric activity coefficient. The effects of these two parameters on the curvature of the adsorption isotherm and the resulting chromatogram are investigated. It could be shown that they can be determined by inverse peak fitting and conform with the mechanistic demands of model-based process development.

  12. 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.

  13. 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.

  14. Cortical current density oscillations in the motor cortex are correlated with muscular activity during pedaling exercise.

    PubMed

    Schneider, S; Rouffet, D M; Billaut, F; Strüder, H K

    2013-01-03

    Despite modern imaging techniques, assessing and localizing changes in brain activity during whole-body exercise is still challenging. Using an active electroencephalography (EEG) system in combination with source localization algorithms, this study aimed to localize brain cortical oscillations patterns in the motor cortex and to correlate these with surface electromyography (EMG)-detected muscular activity during pedaling exercise. Eight subjects performed 2-min isokinetic (90 rpm) cycling bouts at intensities ranging from 1 to 5 Wkg(-1) body mass on a cycle ergometer. These bouts were interspersed by a minimum of 2 min of passive rest to limit to development of peripheral muscle fatigue. Brain cortical activity within the motor cortex was analyzed using a 32-channel active EEG system combined with source localization algorithms. EMG activity was recorded from seven muscles on each lower limb. EEG and EMG activity revealed comparatively stable oscillations across the different exercise intensities. More importantly, the oscillations in cortical activity within the motor cortex were significantly correlated with EMG activity during the high-intensity cycling bouts. This study demonstrates that it is possible to localize oscillations in brain cortical activity during moderate- to high-intensity cycling exercise using EEG in combination with source localization algorithms, and that these oscillations match the activity of the active muscles in time and amplitude. Results of this study might help to further evaluate the effects of central vs. peripheral fatigue during exercise.

  15. 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).

  16. Study of the process of dust grain discharging in the afterglow of an RF discharge

    SciTech Connect

    Filatova, I. I.; Trukhachev, F. M.; Chubrik, N. I.

    2011-12-15

    The process of decay of dust structures formed of polydisperse grains injected into an RF discharge is investigated. The dust grain velocities after switching-off of the discharge are measured. The number density, dimensions, and residual charges of dust grains are estimated from the balance of forces acting on the grains after discharge is switched off.

  17. Comparison of polar cap electron density enhancement due to solar illumination and geomagnetic activity as measured by IMAGE/RPI

    NASA Astrophysics Data System (ADS)

    Nsumei, P.; Reinisch, B.; Song, P.; Tu, J.; Huang, X.

    2007-12-01

    Polar cap electron density (Ne) measurements made between the years 2000 - 2005 by the radio plasma imager (RPI) on board the IMAGE spacecraft are used to study the density enhancements resulting from changes in solar illumination and geomagnetic activity level. This study covers a geocentric distance, R = 1.4 - 5.0 RE and the polar cap is defined by an empirical boundary model that takes into account the dynamic nature of the location and size of the polar cap. The average polar cap electron density profile depends on geomagnetic activity level e.g., measured by the Kp index and solar illumination (solar zenith angle) at the footprints of the geomagnetic field lines. Our analysis of RPI Ne data shows that increase in geomagnetic activity leads to an enhancement in Ne. This enhancement in Ne is found to increase with altitude. At geocentric distance of R = 4.5 RE, an increase in the geomagnetic activity level from Kp < 2 to ~5 results in an Ne increase by a factor of ~5. On the other hand, a strong solar illumination control of Ne at lower altitudes, and not at higher is observed. At geocentric distance of ~ 2 RE, the average Ne is larger on the sunlit side than on the dark side by a factor of 3 - 4 both for quiet and disturbed conditions. At geocentric distance of about 2.5 RE the effects of these two factors on Ne appear to be comparable. Similar to previous polar cap density models, a functional representation of RPI Ne that takes the form of a power law is proposed. While in the previous Ne functional representations the power index is a constant, the power index in our representation of Ne distribution is found to correlate with (and hence is a function of) the Kp index and the solar zenith angle (SZA).

  18. The role of grain size in He bubble formation: Implications for swelling resistance

    NASA Astrophysics Data System (ADS)

    El-Atwani, O.; Nathaniel, J. E.; Leff, A. C.; Muntifering, B. R.; Baldwin, J. K.; Hattar, K.; Taheri, M. L.

    2017-02-01

    Nanocrystalline metals are postulated as radiation resistant materials due to their high defect and particle (e.g. Helium) sink density. Here, the performance of nanocrystalline iron films is investigated in-situ in a transmission electron microscope (TEM) using He irradiation at 700 K. Automated crystal orientation mapping is used in concert with in-situ TEM to explore the role of grain orientation and grain boundary character on bubble density trends. Bubble density as a function of three key grain size regimes is demonstrated. While the overall trend revealed an increase in bubble density up to a saturation value, grains with areas ranging from 3000 to 7500 nm2 show a scattered distribution. An extrapolated swelling resistance based on bubble size and areal density indicated that grains with sizes less than 2000 nm2 possess the greatest apparent resistance. Moreover, denuded zones are found to be independent of grain size, grain orientation, and grain boundary misorientation angle.

  19. 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

  20. Using a Differential Emission Measure and Density Measurements in an Active Region Core to Test a Steady Heating Model

    NASA Astrophysics Data System (ADS)

    Winebarger, Amy R.; Schmelz, Joan T.; Warren, Harry P.; Saar, Steve H.; Kashyap, Vinay L.

    2011-10-01

    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.

  1. Host density and human activities mediate increased parasite prevalence and richness in primates threatened by habitat loss and fragmentation.

    PubMed

    Mbora, David N M; McPeek, Mark A

    2009-01-01

    1. Habitat loss and fragmentation are the principal causes of the loss of biological diversity. In addition, parasitic diseases are an emerging threat to many animals. Nevertheless, relatively few studies have tested how habitat loss and fragmentation influence the prevalence and richness of parasites in animals. 2. Several studies of nonhuman primates have shown that measures of human activity and forest fragmentation correlate with parasitism in primates. However, these studies have not tested for the ecological mechanism(s) by which human activities or forest fragmentation influence the prevalence and richness of parasites. 3. We tested the hypothesis that increased host density due to forest fragmentation and loss mediates increases in the prevalence and richness of gastrointestinal parasites in two forest primates, the Tana River red colobus (Procolobus rufomitratus, Peters 1879) and mangabey (Cercocebus galeritus galeritus, Peters 1879). We focused on population density because epidemiological theory states that host density is a key determinant of the prevalence and richness of directly transmitted parasites in animals. 4. The Tana River red colobus and mangabey are endemic to a highly fragmented forest ecosystem in eastern Kenya where habitat changes are caused by a growing human population increasingly dependent on forest resources and on clearing forest for cultivation. 5. We found that the prevalence of parasites in the two monkeys was very high compared to primates elsewhere. Density of monkeys was positively associated with forest area and disturbance in forests. In turn, the prevalence and richness of parasites was significantly associated with monkey density, and attributes indicative of human disturbance in forests. 6. We also found significant differences in the patterns of parasitism between the colobus and the mangabey possibly attributable to differences in their behavioural ecology. Colobus are arboreal folivores while mangabeys are terrestrial

  2. New light on the Co-C bond activation in B 12-dependent enzymes from density functional theory

    NASA Astrophysics Data System (ADS)

    Andruniow, Tadeusz; Zgierski, Marek Z.; Kozlowski, Pawel M.

    2000-12-01

    Density functional theory (DFT) is applied to the calculation of activation of the Co-C R bond in models of vitamin B 12, B-[Co III(corrin)]-R. It is shown that there is a positive correlation of the bond lengths between the Co atom and the two axial ligands, B and R. The electron donation from axial ligands to the cobalt atom either by electron donating substituents or by a properly oriented external electric field caused by external electric charges is argued to be the main trigger for the activation of the Co-C R bond.

  3. 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.

  4. Density: A Discovery Approach.

    ERIC Educational Resources Information Center

    Rieck, William

    1994-01-01

    Describes an activity that allows students to discover the concept of density and that density is a determining physical property of a pure substance. Makes suggestions to further enhance students' understanding of density. (ZWH)

  5. 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.

  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 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.

  7. 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.

  8. Microstructural changes in beta-silicon nitride grains upon crystallizing the grain-boundary glass

    NASA Technical Reports Server (NTRS)

    Lee, William E.; Hilmas, Gregory E.

    1989-01-01

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

  9. 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.

  10. Grain Boundary (GB) Studies in Nano- and Micro- Crystalline Materials

    NASA Astrophysics Data System (ADS)

    Tanju, Sohanazaman

    2011-12-01

    Polycrystalline materials are composed of grains and grain boundaries. The total volume of occupied grain boundaries in polycrystalline material depends on the grain size. When grain size decreases the volume fraction of grain boundaries increases. For example, when grain size is 10 nm grain boundary volume fraction is ˜ 25%. In polycrystalline materials, different properties (mechanical, electrical, optical, magnetic) are affected by the size of their grains and by the atomic structure of their grain boundaries. Nanocrystalline materials have unique properties compared to coarse grain counterpart because of the presence of more grain boundaries. Increased understanding of the role of grain boundaries play in nanocrystalline materials promotes the tunning of materials properties. In order to study the grain boundaries in different materials, fully dense bulk materials are processed using Current Activated Pressure Assisted Densification (CAPAD) technique. CAPAD is a unique technique for materials processing. It offers faster processing of nanoscale materials compared to traditional sintering technique. Joule heating and pressure are used to densify the materials in CAPAD system. X-ray analysis, Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) are used to characterize the materials. There are three different parts in this dissertation: (1) Affect of grain size on grain boundary curvature on different materials; for example, nano and micro crystalline aluminum (metallic bond), silicon (covalent bond) and iron oxide (ionic bond); (2) Grain boundary geometry analysis of nanocrystalline materials and (3) Grain size dependent electrical and optical property investigation. In the first part of the dissertation, the effect of grain size on the grain boundary curvature is investigated. Several different types of materials were chosen, such as, micro and nano crystalline aluminum (Al), silicon (Si) and iron oxide (Fe2O3). It is found that the

  11. Modeling and design of two-dimensional membrane-type active acoustic metamaterials with tunable anisotropic density.

    PubMed

    Allam, Ahmed; Elsabbagh, Adel; Akl, Wael

    2016-11-01

    A two-dimensional active acoustic metamaterial with controllable anisotropic density is introduced. The material consists of composite lead-lead zirconate titanate plates clamped to an aluminum structure with air as the background fluid. The effective anisotropic density of the material is controlled, independently for two orthogonal directions, by means of an external static electric voltage signal. The material is used in the construction of a reconfigurable waveguide capable of controlling the direction of the acoustic waves propagating through it. An analytic model based on the acoustic two-port theory, the theory of piezoelectricity, the laminated pre-stressed plate theory, and the S-parameters retrieval method is developed to predict the behavior of the material. The results are verified using the finite element method. Excellent agreement is found between both models for the studied frequency and voltage ranges. The results show that, below 1600 Hz, the density is controllable within orders of magnitude relative to the uncontrolled case. The results also suggest that simple controllers could be used to program the material density toward full control of the directivity and dispersion characteristics of acoustic waves.

  12. [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

  13. 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…

  14. Effect of TiO2 on Sintering and Grain Growth Kinetics of MgO from MgCl2·6H2O

    NASA Astrophysics Data System (ADS)

    Huang, Qiong-Zhu; Lu, Gui-Min; Sun, Ze; Song, Xing-Fu; Yu, Jian-Guo

    2013-04-01

    The effect of TiO2 on the grain growth kinetics of MgO prepared from MgCl2·6H2O was studied by the tradition phenomenological rate equation. The results showed that the addition of TiO2 decreased the activation energy of MgO grain growth, accelerated the growth rate of MgO grain, and markedly promoted the sintering of MgO. Without TiO2 addition, the MgO grain growth exponent n was 3, the grain growth activation energy Q was 556.9 kJ·mol-1, and the process was considered as volume diffusion controlled. With 0.2 wt pct TiO2 addition, the MgO grain growth exponent n was 2, the grain growth activation energy Q was 272.8 kJ·mol-1, and the process was considered as interface diffusion controlled. The apparent and closed porosities of MgO-0.2 wt pct TiO2 sample were decreased significantly, and the bulk density increased to 3.49 g·cm-3 (relative density is 97.5 pct). The main mechanism of TiO2 promoting the sintering of MgO was that TiO2 solubilized in MgO to form unequivalence substitutional solid solutions and cation vacancies that were favorable to cation diffusion.

  15. Topside ionosphere bubbles, seen as He+ density depletions: connection with ESF, vertical plasma drift, thermosphere wind and solar activity

    NASA Astrophysics Data System (ADS)

    Sidorova, Larissa

    He+ density depletions, considered as originating from equatorial plasma bubbles (PB), or as possible fossil bubble signatures, were involved in this study. He+ density depletions were observed during a high solar activity (1978-79, F10.7 200) at the topside ionosphere altitudes deeply inside the plasmasphere (L 1.3-3) (Karpachev and Sidorova, ASR, 2002; Sidorova, ASR, 2004, 2007). It is suggested that the equatorial F region irregularities, their post sunset development, evolution, and decay processes are controlled by the sunset electrodynamics of the equatorial region. The He+ density depletion peculiarities were considered in connection with equatorial F-spread (ESF) and vertical plasma drift. The depletion values as function of local time (evening-night hours) were compared with the vertical plasma drift velocity variations, obtained for the same periods (1978-79, F10.7 200; AE-E, IS radar, Jicamarca). Striking similarity in development dynamics was revealed for the different seasons. The monthly mean PB occurrence probability, plotted in local time versus month, was compared with the similar plots for global ESF occurrence probability, derived from ISS-b data (1978-79). Good seasonal correlation (R=0.6) was obtained. Moreover, the comparison of the regional maps, derived from ground-based ionograms, obtained over Brazilian regions (Abdu et al., ASR, 2000) for period with the similar solar activity (1980-81, F10.7 230), shows very well correlation (R=0.67). It is also suggested, that the PBs, produced by Rayleigh-Taylor (R-T) instability at the bottomside of ionosphere and transported up to the topside ionosphere/plasmasphere, could be strong affected by meridional wind during a generation due to inhibiting the growth of R-T instability and flux tube integrated conductivity. For better understanding competing/complementary roles of thermospheric winds in the development of PBs, seen as He+ density depletions, the evaluation of the possible influence of the

  16. Density matrix renormalization group (DMRG) method as a common tool for large active-space CASSCF/CASPT2 calculations

    NASA Astrophysics Data System (ADS)

    Nakatani, Naoki; Guo, Sheng

    2017-03-01

    This paper describes an interface between the density matrix renormalization group (DMRG) method and the complete active-space self-consistent field (CASSCF) method and its analytical gradient, as well as an extension to the second-order perturbation theory (CASPT2) method. This interfacing allows large active-space multi-reference computations to be easily performed. The interface and its extension are both implemented in terms of reduced density matrices (RDMs) which can be efficiently computed via the DMRG sweep algorithm. We also present benchmark results showing that, in practice, the DMRG-CASSCF calculations scale with active-space size in a polynomial manner in the case of quasi-1D systems. Geometry optimization of a binuclear iron-sulfur cluster using the DMRG-CASSCF analytical gradient is demonstrated, indicating that the inclusion of the valence p-orbitals of sulfur and double-shell d-orbitals of iron lead to non-negligible changes in the geometry compared to the results of small active-space calculations. With the exception of the selection of M values, many computational settings in these practical DMRG calculations have been tuned and black-boxed in our interface, and so the resulting DMRG-CASSCF and DMRG-CASPT2 calculations are now available to novice users as a common tool to compute strongly correlated electronic wavefunctions.

  17. Antioxidant activity of thiocholesterol on copper-induced oxidation of low-density lipoprotein.

    PubMed

    Tanaka, M; Nakagawa, M

    1995-04-01

    The effect of thiocholesterol (SH-Chol) on the copper-induced in vitro oxidation of low-density lipoprotein (LDL; 1.019 < d < 1.063) was investigated. Among the antioxidants tested, including cysteine, glutathione, 2-mercaptoethanol, dithiothreitol, probucol, thiopalmitic acid, and SH-Chol, SH-Chol was the most effective antioxidant in copper-induced LDL oxidation. Also, SH-Chol completely inhibited the formation of oxysterols, i.e., 7-hydroxycholesterol and 7-ketocholesterol, in LDL particles and reduced 1,1-diphenyl-2-picrylhydrazyl used as stable free-radical model. Moreover, SH-Chol suppressed the degradation of endogenous alpha-tocopherol in LDL particles. These findings indicate that SH-Chol acts as antioxidant in the oxidative damage of LDL in vitro and as a free-radical scavenger in lipid peroxidation.

  18. 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

  19. 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.

  20. 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.

  1. The role of secondary phase precipitation on grain boundary electrical activity in Cu2ZnSnS4 (CZTS) photovoltaic absorber layer material

    NASA Astrophysics Data System (ADS)

    Mendis, Budhika G.; Goodman, Max C. J.; Major, Jonathan D.; Taylor, Aidan A.; Durose, Ken; Halliday, Douglas P.

    2012-12-01

    Cathodoluminescence is used to measure the recombination velocity of the heterointerfaces between Cu2ZnSnS4 (CZTS) and CuxSnySz, SnS secondary phases precipitated along the grain boundaries as well as ZnS precipitated within the CZTS grain interiors. The CZTS/CuxSnySz and CZTS/ZnS heterointerfaces had recombination velocities smaller than the bulk carrier diffusion velocity while the opposite is true for the CZTS/SnS heterointerface. Secondary phases having crystal structures compatible with CZTS (e.g., ZnS, Cu2SnS3) are likely to form heterointerfaces with small misfit strain and hence low interfacial recombination velocity. The precipitation of such secondary phases along grain boundaries in CZTS provides a novel mechanism for grain boundary passivation. However, it is not known if grain boundary passivating secondary phases would necessarily increase the overall photovoltaic device efficiency since other factors, such as the band gap of the secondary phase compared to the Shockley-Queisser ideal value and the nature of the heterointerface between CZTS (i.e., type-I vs type-II), also affect device operation and must therefore be taken into consideration.

  2. 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.

  3. Loading dose of physical activity is related to muscle strength and bone density in middle-aged women.

    PubMed

    Chahal, Jaswinder; Lee, Raymond; Luo, Jin

    2014-10-01

    The aim of the current study was to investigate the association between loading dose of physical activity, muscle strength and bone density in middle-aged women. Thirty four healthy women (mean age=49.8±7.5years) were recruited. They were requested to wear an accelerometer for a period of 10h (from 9am to 7pm) on a day to record the acceleration. On a separate day their knee extension torque (KET) was measured using an isokinetic dynamometer and broadband ultrasound attenuation (BUA) at the heel by an ultrasound bone scanner. The loading dose of physical activity was calculated at four intensity categories - very light, light, moderate, and vigorous (intensities of <5BW/s, 5-10BW/s, 10-15BW/s and >15BW/s) and for three frequency bands - 0.1-2Hz, 2-4Hz, and 4-6Hz. Correlation analysis was used to examine the association between loading dose and age, KET, and BUA. With the increase of age, there tended to be a decrease in the loading dose of vigorous activity in 2-4 and 4-6Hz frequency bands (Kendall's tau=-.22, p<.1). The increase of loading dose in all three frequency bands in moderate or vigorous activity was associated with higher BUA (Kendall's tau=.27-.41, p<.05). The increase of loading dose in all frequency bands in light, moderate, or vigorous activity was associated with higher KET (Kendall's tau=.30-.45, p<.05). It is concluded that physical activity, especially that at high intensity level and high frequency range, may have beneficial effect on muscle strength and bone density in middle-aged women.

  4. Effect of the Heat-exposure on Peripheral Sudomotor Activity Including the Density of Active Sweat Glands and Single Sweat Gland Output.

    PubMed

    Lee, Jeong-Beom; Kim, Tae-Wook; Shin, Young-Oh; Min, Young-Ki; Yang, Hun-Mo

    2010-10-01

    Tropical inhabitants are able to tolerate heat through permanent residence in hot and often humid tropical climates. The goal of this study was to clarify the peripheral mechanisms involved in thermal sweating pre and post exposure (heat-acclimatization over 10 days) by studying the sweating responses to acetylcholine (ACh), a primary neurotransmitter of sudomotor activity, in healthy subjects (n=12). Ten percent ACh was administered on the inner forearm skin for iontophoresis. Quantitative sudomotor axon reflex testing, after iontophoresis (2 mA for 5 min) with ACH, was performed to determine directly activated (DIR) and axon reflex-mediated (AXR) sweating during ACh iontophoresis. The sweat rate, activated sweat gland density, sweat gland output per single gland activated, as well as oral and skin temperature changes were measured. The post exposure activity had a short onset time (p<0.01), higher active sweat rate [(AXR (p<0.001) and DIR (p<0.001)], higher sweat output per gland (p<0.001) and higher transepidermal water loss (p<0.001) compared to the pre-exposure measurements. The activated sweat rate in the sudomotor activity increased the output for post-exposure compared to the pre-exposure measurements. The results suggested that post-exposure activity showed a higher active sweat gland output due to the combination of a higher AXR (DIR) sweat rate and a shorter onset time. Therefore, higher sudomotor responses to ACh receptors indicate accelerated sympathetic nerve responsiveness to ACh sensitivity by exposure to environmental conditions.

  5. Relationship between grain boundary complexion and grain growth kinetics in alumina

    NASA Astrophysics Data System (ADS)

    Dillon, Shen J.

    2007-12-01

    This work investigated the effect of different grain boundary phases (complexions) on the grain growth kinetics of doped and undoped aluminas. This was achieved by relating quantitative grain growth kinetics to high-resolution electron microscopy of the grain boundaries. It was found that there are 6 different regimes into which the grain growth kinetics may be categorized. These regimes corresponded to the existence of six different grain boundary complexions. Grain boundaries in alumina were observed to show sub-monolayer adsorption, 'clean' intrinsic behavior, bilayer adsorption, multilayer adsorption, equilibrium thickness intergranular films, and wetting intergranular films. These different grain boundary types are listed in order of increasing grain boundary mobility. In general there is an increase in grain boundary mobility with an increase in the disorder within the core of the grain boundary. This broad range of grain boundaries produces a multiplicity of different microstructural effects that until now have been difficult to understand experimentally or theoretically. For example, abnormal grain growth in alumina simply results from the coexistence of two or more different complexions within the same microstructure. Therefore, there may be multiple distinct types of normal and abnormal grain growth behavior. Transitions from one type of boundary to another are chemically and thermally activated, and depend on the crystallography of the adjacent grains. It is found that the number of transitions that occur increases linearly with increasing grain size, and exponentially with temperature. In this regard, different dopants produce very different effects, which appear to be the major role of most dopants in affecting the grain boundary transport kinetics. Low energy planes and grain boundaries are the least likely to undergo such transitions. This experimental data compliments some theoretical derivations within the literature and has provided new insight

  6. Constitutive activation of CREB in mice enhances temporal association learning and increases hippocampal CA1 neuronal spine density and complexity

    PubMed Central

    Serita, Tatsurou; Fukushima, Hotaka; Kida, Satoshi

    2017-01-01

    Transcription factor CREB is believed to play essential roles in the formation of long-term memory (LTM), but not in learning and short-term memory (STM). Surprisingly, we previously showed that transgenic mice expressing a dominant active mutant of CREB (DIEDML) in the forebrain (DIEDML mice) demonstrated enhanced STM and LTM in hippocampal-dependent, rapid, one-trial learning tasks. Here we show that constitutive activation of CREB enhances hippocampal-dependent learning of temporal association in trace fear conditioning and delayed matching-to-place tasks. We then show that in DIEDML mice the apical tuft dendrites of hippocampal CA1 pyramidal neurons, required for temporal association learning, display increased spine density, especially of thin spines and of Homer1-negative spines. In contrast, the basal and apical oblique dendrites of CA1 neurons, required for rapid one-trial learning, show increased density of thin, stubby, and mushroom spines and of Homer1-positive spines. Furthermore, DIEDML mice showed increased dendritic complexity in the proximal portion of apical CA1 dendrites to the soma. In contrast, forebrain overexpression of CaMKIV, leading to enhanced LTM but not STM, show normal learning and CA1 neuron morphology. These findings suggest that dendritic region-specific morphological changes in CA1 neurons by constitutive activation of CREB may contribute to improved learning and STM. PMID:28195219

  7. Seasonal Variation in Population Density and Heterotrophic Activity of Attached and Free-Living Bacteria in Coastal Waters

    PubMed Central

    Iriberri, Juan; Unanue, Marian; Barcina, Isabel; Egea, Luis

    1987-01-01

    The abundance and heterotrophic activity of attached and free-living bacteria were examined seasonally in coastal water. Heterotrophic activity was determined by the uptake of [14C]glucose. The density of attached bacteria was always minor, not showing a seasonal variation, whereas the free-living bacteria were more numerous and showed a marked seasonal variation, their density being higher under warmer conditions. The contribution of the attached bacteria to the total assimilation of [14C]glucose (from 10 to 38%) was lower than that of the free-living bacteria, neither of them showing a seasonal variation. On a cellular basis, attached bacteria were more active, since they assimilated more [14C]glucose and showed, under warmer conditions, a higher cellular volume (0.102 versus 0.047 μm3). We consider that the factors responsible for these observations were the amount and quality of the particulate material, the different availability of organic matter for the two types of bacteria, and in a fundamental way, the variation in water temperature. PMID:16347451

  8. Constitutive activation of CREB in mice enhances temporal association learning and increases hippocampal CA1 neuronal spine density and complexity.

    PubMed

    Serita, Tatsurou; Fukushima, Hotaka; Kida, Satoshi

    2017-02-14

    Transcription factor CREB is believed to play essential roles in the formation of long-term memory (LTM), but not in learning and short-term memory (STM). Surprisingly, we previously showed that transgenic mice expressing a dominant active mutant of CREB (DIEDML) in the forebrain (DIEDML mice) demonstrated enhanced STM and LTM in hippocampal-dependent, rapid, one-trial learning tasks. Here we show that constitutive activation of CREB enhances hippocampal-dependent learning of temporal association in trace fear conditioning and delayed matching-to-place tasks. We then show that in DIEDML mice the apical tuft dendrites of hippocampal CA1 pyramidal neurons, required for temporal association learning, display increased spine density, especially of thin spines and of Homer1-negative spines. In contrast, the basal and apical oblique dendrites of CA1 neurons, required for rapid one-trial learning, show increased density of thin, stubby, and mushroom spines and of Homer1-positive spines. Furthermore, DIEDML mice showed increased dendritic complexity in the proximal portion of apical CA1 dendrites to the soma. In contrast, forebrain overexpression of CaMKIV, leading to enhanced LTM but not STM, show normal learning and CA1 neuron morphology. These findings suggest that dendritic region-specific morphological changes in CA1 neurons by constitutive activation of CREB may contribute to improved learning and STM.

  9. Using Passive and Active Acoustics to Examine Relationships of Cetacean and Prey Densities

    DTIC Science & Technology

    2015-09-30

    mounted on a glider running on two California Cooperative Oceanic Fisheries Investigations (CalCOFI) lines and passive as well as active acoustic...Southwest Fisheries Science Center. WORK COMPLETED A preliminary experiment was carried out (see section Results) that documented sound production

  10. [Effect of preparations exhibiting cytokinin-like activity on the specific density of leaf in grasses].

    PubMed

    Cherniad'ev, I I

    2002-01-01

    The effects of synthetic preparations exhibiting cytokinin-like activity (6-benzylaminopurine, Thidiazuron, and kartolin-2) on the specific leaf area (SLA) were studied in plants of the family Gramineae (wheat, Triticum aestivum L.; meadow fescue, Festuca pratensis Huds.; and reed fescue, F. arindinacea Schreb.). At the early stages of ontogeny (until the leaf area reached 50-60% of the maximum value), treatment of plants of the three species with cytokinin-like preparations caused an increase in SLA. The SLA value in these plants was correlated with the rate of photosynthetic assimilation of carbon dioxide and activities of carbon metabolism enzymes: ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), NAD-malate dehydrogenase (EC 1.1.1.37), and NADP-glyceraldehydrophosphate dehydrogenase complex, which includes phosphoglycerate kinase (EC 2.7.2.3) and glyceraldehydrophosphate dehydrogenase (EC 1.2.1.13). However, there was no correlation of SLA with the activity of phospho(enol)pyruvate carboxylase (EC 4.1.1.31), an anaplerotic carboxylation enzyme of grasses. SLA is suggested to reflect the state and activity of the photosynthetic apparatus and can be recommended as a characteristic of photosynthesis variability (e.g., caused by cytokinin-like preparations).

  11. 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

  12. Early Left Parietal Activity Elicited by Direct Gaze: A High-Density EEG Study

    PubMed Central

    Burra, Nicolas; Kerzel, Dirk; George, Nathalie

    2016-01-01

    Gaze is one of the most important cues for human communication and social interaction. In particular, gaze contact is the most primary form of social contact and it is thought to capture attention. A very early-differentiated brain response to direct versus averted gaze has been hypothesized. Here, we used high-density electroencephalography to test this hypothesis. Topographical analysis allowed us to uncover a very early topographic modulation (40–80 ms) of event-related responses to faces with direct as compared to averted gaze. This modulation was obtained only in the condition where intact broadband faces–as opposed to high-pass or low-pas filtered faces–were presented. Source estimation indicated that this early modulation involved the posterior parietal region, encompassing the left precuneus and inferior parietal lobule. This supports the idea that it reflected an early orienting response to direct versus averted gaze. Accordingly, in a follow-up behavioural experiment, we found faster response times to the direct gaze than to the averted gaze broadband faces. In addition, classical evoked potential analysis showed that the N170 peak amplitude was larger for averted gaze than for direct gaze. Taken together, these results suggest that direct gaze may be detected at a very early processing stage, involving a parallel route to the ventral occipito-temporal route of face perceptual analysis. PMID:27880776

  13. Giant-amplitude, high-work density microactuators with phase transition activated nanolayer bimorphs.

    PubMed

    Liu, Kai; Cheng, Chun; Cheng, Zhenting; Wang, Kevin; Ramesh, Ramamoorthy; Wu, Junqiao

    2012-12-12

    Various mechanisms are currently exploited to transduce a wide range of stimulating sources into mechanical motion. At the microscale, simultaneously high amplitude, high work output, and high speed in actuation are hindered by limitations of these actuation mechanisms. Here we demonstrate a set of microactuators fabricated by a simple microfabrication process, showing simultaneously high performance by these metrics, operated on the structural phase transition in vanadium dioxide responding to diverse stimuli of heat, electric current, and light. In both ambient and aqueous conditions, the actuators bend with exceedingly high displacement-to-length ratios up to 1 in the sub-100 μm length scale, work densities over 0.63 J/cm(3), and at frequencies up to 6 kHz. The functionalities of actuation can be further enriched with integrated designs of planar as well as three-dimensional geometries. Combining the superior performance, high durability, diversity in responsive stimuli, versatile working environments, and microscale manufacturability, these actuators offer potential applications in microelectromechanical systems, microfluidics, robotics, drug delivery, and artificial muscles.

  14. 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.

  15. High-density tiling microarray analysis of the full transcriptional activity of yeast.

    PubMed

    David, Lior; Clauder-Münster, Sandra; Steinmetz, Lars M

    2014-01-01

    Understanding the relationship between DNA sequence variation and phenotypic variation in complex or quantitative traits is one of the major challenges in modern biology. We are witnessing a deluge of DNA sequence information and association studies of genetic polymorphisms with phenotypes of interest in families and populations. In addition, it has become clear that large portions of eukaryotic genomes beyond protein-coding genes are transcribed, generating numerous noncoding RNA (ncRNA) molecules whose functions remain mostly unknown.DNA oligonucleotide microarrays constitute a powerful technology for studying the expression of genes in different organisms. The Saccharomyces cerevisiae tiling array presents a significant advance over previous array-based platforms. It has a high density of overlapping probes that start on average every 8 bp along each strand of the genome, enabling precise definition of transcript structure. Furthermore, the array includes probes specific for the polymorphic positions of another, distantly related yeast strain, allowing accurate measurement of allele-specific expression in a hybrid of the two strains. This technology thus allows high-resolution, quantitative, strand- and allele-specific measurements of transcription from a full eukaryotic genome. In this chapter, we describe the methods for extracting RNA, synthesizing first-strand cDNA, fragmenting, and labeling of samples for hybridization to the tiling array. Combining genome-wide information on variation in DNA sequence with variation in transcript structure and levels promises to increase our understanding of the genotype-to-phenotype relationship.

  16. Grain boundary behavior in varistor-capacitor TiO2-rich CaCu3Ti4O12 ceramics

    NASA Astrophysics Data System (ADS)

    Lin, Yuan-Hua; Cai, Jingnan; Li, Ming; Nan, Ce-Wen; He, Jinliang

    2008-04-01

    We prepared TiO2-rich CaCu3Ti4O12 (CCTO) ceramics by a solid-state sintering process and observed large nonlinear electrical and high dielectric behaviors. Microstructure and phase composition analyses show that CCTO grain-amorphous/TiO2 nanograin boundary-CCTO grain junction structures exist in these TiO2-rich CCTO ceramics, which leads to the nonlinear electrical and high dielectric properties. The temperature dependence of impedance spectroscopy and relationships between electrical current density versus applied electrical field indicate that the activation energy of the grain boundary for the TiO2-rich CCTO ceramics is almost the same as the potential barrier height and both of them are weakly independent of the doped concentration of TiO2, which supports the internal barrier layer capacitor model of Schottky barriers at the grain boundaries between semiconducting CCTO grains.

  17. Auroral electrodynamics I: 1. preliminary electron density profile and 2. vehicle potential changes during an active beam experiment. Memorandum report

    SciTech Connect

    Walker, D.N.; Holmes, J.C.; Szuszczewicz, E.P.

    1980-05-19

    The report presents preliminary findings obtained by a pulsed plasma probe aboard a payload launched by a Terrier-Malemute sounding rocket from the Poker Flat Research Range. Results are outlined both during passive and active (i.e., an Argon plasma gun) experiments. Modifications to the design of the pulsed probe circuitry which allow tracking of the vehicle potential are described. The vehicle potential deduced from the analog records is plotted during times of interest (gun pulsing periods). An electron density profile with gun pulsing times indicated is also provided.

  18. Effects of whole grains on coronary heart disease risk.

    PubMed

    Harris, Kristina A; Kris-Etherton, Penny M

    2010-11-01

    Characterizing which types of carbohydrates, including whole grains, reduce the risk for coronary heart disease (CHD) is challenging. Whole grains are characterized as being high in resistant carbohydrates as compared with refined grains, meaning they typically are high in fiber, nutrients, and bound antioxidants. Whole grain intake consistently has been associated with improved cardiovascular disease outcomes, but also with healthy lifestyles, in large observational studies. Intervention studies that assess the effects of whole grains on biomarkers for CHD have mixed results. Due to the varying nutrient compositions of different whole grains, each could potentially affect CHD risk via different mechanisms. Whole grains high in viscous fiber (oats, barley) decrease serum low-density lipoprotein cholesterol and blood pressure and improve glucose and insulin responses. Grains high in insoluble fiber (wheat) moderately lower glucose and blood pressure but also have a prebiotic effect. Obesity is inversely related to whole grain intake, but intervention studies with whole grains have not produced weight loss. Visceral fat, however, may be affected favorably. Grain processing improves palatability and can have varying effects on nutrition (e.g., the process of milling and grinding flour increases glucose availability and decreases phytochemical content whereas thermal processing increases available antioxidants). Understanding how individual grains, in both natural and processed states, affect CHD risk can inform nutrition recommendations and policies and ultimately benefit public health.

  19. 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

  20. 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.

  1. Studies of High Power Density, Pico-Second Rise-Time Light Activated Semiconductor Switch

    DTIC Science & Technology

    1988-12-31

    34 Proceedings of the IEEE, vol.55, pp.2192-2193, 1967. 3. McKay, K., K. McAfee, "Electron Multiplication in Silicon and Germanium ," Physical Review...Conwell, E., "Properties of Silicon and Germanium : II," Proceedings of the Institute of Radio Engineers. vol.46, pp.1281-1300, 1958. 6. Zucker, 0...light activated semiconductor switches made of silicon junction diode have been demonstrated. A novel optical delay line has been designed in sampling

  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. The density-of-states concept versus the experimentally determined distribution of activation energies

    SciTech Connect

    Adriaenssens, G.J.; Arkhipov, V.I.

    1996-12-31

    Random fluctuations of localized state energies will result in thermal release of carriers trapped in those states at shorter times than would be observed from a stationary distribution of the same energies. An experimentally observed distribution of activation energies will hence differ from the distribution of average energies of the states involved. It will also be temperature-dependent. In a-Si:H, low-frequency fluctuations with a spectrum comparable to the one of 1/f noise, can account for the measured temperature dependence of the distribution. They also explain the apparent shift in localized-state energy under steady-state illumination.

  4. What Controls Ooid Grain Size?

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  5. 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...

  6. Charging time for dust grain on surface exposed to plasma

    SciTech Connect

    Sheridan, T. E.

    2013-04-14

    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.

  7. Accretion growth of water-ice grains in astrophysically-relevant dusty plasma experiment

    NASA Astrophysics Data System (ADS)

    Chai, Kil-Byoung; Marshall, Ryan; Bellan, Paul

    2016-10-01

    The grain growth process in the Caltech water-ice dusty plasma experiment has been studied using a high-speed camera equipped with a long-distance microscope lens. It is found that (i) the ice grain number density decreases four-fold as the average grain length increases from 20 to 80 um, (ii) the ice grain length has a log-normal distribution rather than a power-law dependence, and (iii) no collisions between ice grains are apparent. The grains have a large negative charge so the agglomeration growth is prevented by their strong mutual repulsion. It is concluded that direct accretion of water molecules is in good agreement with the observed ice grain growth. The volumetric packing factor of the ice grains must be less than 0.25 in order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains; this conclusion is consistent with ice grain images showing a fractal character.

  8. Density functional theory study on activity of α-Fe 2O 3 in chemical-looping combustion system

    NASA Astrophysics Data System (ADS)

    Dong, Changqing; Sheng, Shuhui; Qin, Wu; Lu, Qiang; Zhao, Ying; Wang, Xiaoqiang; Zhang, Junjiao

    2011-08-01

    The dominant growth planes (0 0 0 1) and (1 1 0 2) have been used to investigate the activity of the natural α-Fe 2O 3 in chemical-looping combustion system based on density functional theory (DFT) calculations. In the chemical-looping combustion system, CO is selected as the probe fuel gas to detect the activities of the different surfaces. CO interacts stronger to Fe 2O 3 (1 1 0 2) than Fe 2O 3 (0 0 0 1). CO can be oxidized into CO 2 species directly on Fe 2O 3 (1 1 0 2) rather than Fe 2O 3 (0 0 0 1). The formation of CO 2 accompanying with a transformation from hematite to magnetite acted as the key step for the reduction process of hematite.

  9. Practical steady-state temperature prediction of active embedded chips into high density electronic board

    NASA Astrophysics Data System (ADS)

    Monier-Vinard, Eric; Rogie, Brice; Nguyen, Nhat-Minh; Laraqi, Najib; Bissuel, Valentin; Daniel, Olivier

    2016-09-01

    Printed Wiring Board die embedding technology is an innovative packaging alternative to address a very high degree of integration by stacking multiple core layers housing active chips. Nevertheless this increases the thermal management challenges by concentrating heat dissipation at the heart of the substrate and exacerbates the need of adequate cooling. In order to allow the electronic designers to early analyse the limits of the in-layer power dissipation, depending on the chip location inside the board, various analytical thermal modelling approaches were investigated. Therefore the buried active chips can be represented using surface or volumetric heating sources according with the expected accuracy. Moreover the current work describes the comparison of the volumetric heating source analytical model with the state-of-art numerical detailed models of several embedded chips configurations, and debates about the need or not to simulate in full details the embedded chips as well as the surrounding layers and micro-via structures of the substrate. The results highlight that the thermal behaviour predictions of the analytical model are found to be within ±5% of relative error and so demonstrate their relevance to model an embedded chip and its neighbouring heating chips or components. Further this predictive model proves to be in good agreement with an experimental characterization performed on a thermal test vehicle. To summarize, the developed analytical approach promotes several practical solutions to achieve a more efficient design and to early identify the potential issues of board cooling.

  10. Stress-activated protein kinases are negatively regulated by cell density.

    PubMed Central

    Lallemand, D; Ham, J; Garbay, S; Bakiri, L; Traincard, F; Jeannequin, O; Pfarr, C M; Yaniv, M

    1998-01-01

    Stimulation by UV irradiation, TNFalpha, as well as PDGF or EGF activates the JNK/SAPK signalling pathway in mouse fibroblasts. This results in the phosphorylation of the N-terminal domain of c-Jun, increasing its transactivation potency. Using an antibody that specifically recognizes c-Jun phosphorylated at Ser63, we show that culture confluency drastically inhibited c-Jun N-terminal phosphorylation due to the inhibition of the JNK/SAPK pathway. Transfection experiments demonstrate that the inhibition occurs at the same level as, or upstream of, the small G-proteins cdc42 and Rac1. In contrast, the classical MAPK pathway was insensitive to confluency. The inhibition of JNK/SAPK activation depended on the integrity of the actin microfilament network. These results were confirmed and extended in monolayer wounding experiments. After PDGF, EGF or UV stimulation, c-Jun was predominantly phosphorylated in cells bordering the wound, which are the cells that move to occupy the wounded area. Thus, modulation of the stress-dependent signal cascade by confluency will restrict c-Jun N-terminal phosphorylation in response to mitogenic or chemotactic agents to cells that border a wounded area. PMID:9755162

  11. Convection in grain refining

    NASA Technical Reports Server (NTRS)

    Flemings, M. C.; Szekely, J.

    1982-01-01

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

  12. Hydrothermal quartz formation during fluctuations of brittle shear-zone activity and fluid flow: grain growth and deformation structures of the Pfahl shear zone (Germany)

    NASA Astrophysics Data System (ADS)

    Yilmaz, T.; Prosser, G.; Liotta, D.; Kruhl, J. H.

    2012-12-01

    , crosscutting the first generations of fine-grained quartz mass and the wall rocks, in connection to intense fracturing and brecciation. The complex geometry of the vein sets points to multiple fluid injections and brecciation, as additionally indicated by coarse quartz with different inclusion and CL intensity. Temporal changes of strain rate are indicated by crystal plastic deformation structures in quartz, which overprint brittle structures. (iv) The fourth quartz generation occurs in mm- to dm-thick quartz veins, partly open as geodes, filling N-S oriented cm- to dm-spaced fractures that crosscut the earlier quartz masses and veins and extend at least several meters into the wall rock. They indicate the last activity of the shear-zone in a constant kinematic framework. Summarizing, the Pfahl shear zone shows brittle-ductile deformation during the long-term activity of a large-scale hydrothermal system. Consequently, it represents an excellent example where different generations of quartz precipitation can be connected to fluctuations of fluid flow and strain rate.

  13. 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.

  14. 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.

  15. Activated expression of an Arabidopsis HD-START protein confers drought tolerance with improved root system and reduced stomatal density.

    PubMed

    Yu, Hong; Chen, Xi; Hong, Yuan-Yuan; Wang, Yao; Xu, Ping; Ke, Sheng-Dong; Liu, Hai-Yan; Zhu, Jian-Kang; Oliver, David J; Xiang, Cheng-Bin

    2008-04-01

    Drought is one of the most important environmental constraints limiting plant growth and agricultural productivity. To understand the underlying mechanism of drought tolerance and to identify genes for improving this important trait, we conducted a gain-of-function genetic screen for improved drought tolerance in Arabidopsis thaliana. One mutant with improved drought tolerance was isolated and designated as enhanced drought tolerance1. The mutant has a more extensive root system than the wild type, with deeper roots and more lateral roots, and shows a reduced leaf stomatal density. The mutant had higher levels of abscisic acid and Pro than the wild type and demonstrated an increased resistance to oxidative stress and high levels of superoxide dismutase. Molecular genetic analysis and recapitulation experiments showed that the enhanced drought tolerance is caused by the activated expression of a T-DNA tagged gene that encodes a putative homeodomain-START transcription factor. Moreover, overexpressing the cDNA of the transcription factor in transgenic tobacco also conferred drought tolerance associated with improved root architecture and reduced leaf stomatal density. Therefore, we have revealed functions of the homeodomain-START factor that were gained upon altering its expression pattern by activation tagging and provide a key regulator that may be used to improve drought tolerance in plants.

  16. 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.

  17. 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 ...

  18. Advantageous grain boundaries in iron pnictide superconductors

    PubMed Central

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

    2011-01-01

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

  19. 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

  20. Whole Grains and Fiber

    MedlinePlus

    ... Oct 11,2016 Any food made from wheat, rice, oats, corn, or another cereal is a grain ... wheat, oats/oatmeal, rye, barley, corn, popcorn, brown rice, wild rice, buckwheat, triticale, bulgur (cracked wheat), millet, ...

  1. Implications of Saito's coronal density model on the polar solar wind flow and heavy ion abundances. [mathematical models of proton flux density and solar activity

    NASA Technical Reports Server (NTRS)

    Feldman, W. C.

    1976-01-01

    A comparison of polar solar wind proton flux upper limits derived using a coronal density model, with Lyman alpha measurements of the length of the neutral H tail of comet Bennet at high latitudes, shows that either extended heating beyond 2 solar radii is necessary some of the time or that the model's polar densities are too low. Whichever possibility is the case, the fact that the solar wind particle flux does not appear to decrease with increasing latitude indicates that the heavy element content of the high latitude wind may be similar to that observed in the ecliptic. It was then shown that solar wind heavy ion observations at high latitudes allow a determination of the electron temperature at heights which bracket the nominal location of the coronal temperature maximum thus providing information concerning the magnitude and extent of mechanical dissipation in the intermediate corona.

  2. High capacitance of coarse-grained carbide derived carbon electrodes

    DOE PAGES

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; ...

    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

  3. 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.

  4. 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.

  5. 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.

  6. Muscle-tendon units localization and activation level analysis based on high-density surface EMG array and NMF algorithm

    NASA Astrophysics Data System (ADS)

    Huang, Chengjun; Chen, Xiang; Cao, Shuai; Zhang, Xu

    2016-12-01

    Objective. Some skeletal muscles can be subdivided into smaller segments called muscle-tendon units (MTUs). The purpose of this paper is to propose a framework to locate the active region of the corresponding MTUs within a single skeletal muscle and to analyze the activation level varieties of different MTUs during a dynamic motion task. Approach. Biceps brachii and gastrocnemius were selected as targeted muscles and three dynamic motion tasks were designed and studied. Eight healthy male subjects participated in the data collection experiments, and 128-channel surface electromyographic (sEMG) signals were collected with a high-density sEMG electrode grid (a grid consists of 8 rows and 16 columns). Then the sEMG envelopes matrix was factorized into a matrix of weighting vectors and a matrix of time-varying coefficients by nonnegative matrix factorization algorithm. Main results. The experimental results demonstrated that the weightings vectors, which represent invariant pattern of muscle activity across all channels, could be used to estimate the location of MTUs and the time-varying coefficients could be used to depict the variation of MTUs activation level during dynamic motion task. Significance. The proposed method provides one way to analyze in-depth the functional state of MTUs during dynamic tasks and thus can be employed on multiple noteworthy sEMG-based applications such as muscle force estimation, muscle fatigue research and the control of myoelectric prostheses. This work was supported by the National Nature Science Foundation of China under Grant 61431017 and 61271138.

  7. A new approach to grain boundary engineering for nanocrystalline materials

    PubMed Central

    Tsurekawa, Sadahiro; Watanabe, Tadao

    2016-01-01

    A new approach to grain boundary engineering (GBE) for high performance nanocrystalline materials, especially those produced by electrodeposition and sputtering, is discussed on the basis of some important findings from recently available results on GBE for nanocrystalline materials. In order to optimize their utility, the beneficial effects of grain boundary microstructures have been seriously considered according to the almost established approach to GBE. This approach has been increasingly recognized for the development of high performance nanocrystalline materials with an extremely high density of grain boundaries and triple junctions. The effectiveness of precisely controlled grain boundary microstructures (quantitatively characterized by the grain boundary character distribution (GBCD) and grain boundary connectivity associated with triple junctions) has been revealed for recent achievements in the enhancement of grain boundary strengthening, hardness, and the control of segregation-induced intergranular brittleness and intergranular fatigue fracture in electrodeposited nickel and nickel alloys with initial submicrometer-grained structure. A new approach to GBE based on fractal analysis of grain boundary connectivity is proposed to produce high performance nanocrystalline or submicrometer-grained materials with desirable mechanical properties such as enhanced fracture resistance. Finally, the potential power of GBE is demonstrated for high performance functional materials like gold thin films through precise control of electrical resistance based on the fractal analysis of the grain boundary microstructure. PMID:28144533

  8. A new approach to grain boundary engineering for nanocrystalline materials.

    PubMed

    Kobayashi, Shigeaki; Tsurekawa, Sadahiro; Watanabe, Tadao

    2016-01-01

    A new approach to grain boundary engineering (GBE) for high performance nanocrystalline materials, especially those produced by electrodeposition and sputtering, is discussed on the basis of some important findings from recently available results on GBE for nanocrystalline materials. In order to optimize their utility, the beneficial effects of grain boundary microstructures have been seriously considered according to the almost established approach to GBE. This approach has been increasingly recognized for the development of high performance nanocrystalline materials with an extremely high density of grain boundaries and triple junctions. The effectiveness of precisely controlled grain boundary microstructures (quantitatively characterized by the grain boundary character distribution (GBCD) and grain boundary connectivity associated with triple junctions) has been revealed for recent achievements in the enhancement of grain boundary strengthening, hardness, and the control of segregation-induced intergranular brittleness and intergranular fatigue fracture in electrodeposited nickel and nickel alloys with initial submicrometer-grained structure. A new approach to GBE based on fractal analysis of grain boundary connectivity is proposed to produce high performance nanocrystalline or submicrometer-grained materials with desirable mechanical properties such as enhanced fracture resistance. Finally, the potential power of GBE is demonstrated for high performance functional materials like gold thin films through precise control of electrical resistance based on the fractal analysis of the grain boundary microstructure.

  9. 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

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

    PubMed

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

    2015-10-05

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

  11. Ultrathin amorphous coatings on lunar dust grains.

    PubMed

    Bibring, J P; Duraud, J P; Durrieu, L; Jouret, C; Maurette, M; Meunier, R

    1972-02-18

    UItrathin amorphous coatings have been observed by high-voltage electron microscopy on micrometer-sized dust grains from the Apollo 11, Apollo 12, Apollo 14, and Luna 16 missions. Calibration experiments show that these coatings result from an "ancient" implantation of solar wind ions in the grains. This phenomenon has interdisciplinary applications concerning the past activity of the sun, the lunar albedo, the ancient lunar atmosphere and magnetic field, the carbon content of lunar soils, and lunar dynamic processes.

  12. Effect of platelet activating factor-acetylhydrolase on the formation and action of minimally oxidized low density lipoprotein.

    PubMed Central

    Watson, A D; Navab, M; Hama, S Y; Sevanian, A; Prescott, S M; Stafforini, D M; McIntyre, T M; Du, B N; Fogelman, A M; Berliner, J A

    1995-01-01

    Mildly oxidized low density lipoprotein (MM-LDL) produced by oxidative enzymes or cocultures of human artery wall cells induces endothelial cells to produce monocyte chemotactic protein-1 and to bind monocytes. HDL prevents the formation of MM-LDL by cocultures of artery wall cells. Using albumin treatment and HPLC we have isolated and partially characterized bioactive oxidized phospholipids in MM-LDL. Platelet activating factor-acetylhydrolase (PAF-AH), a serine esterase, hydrolyzes short chain acyl groups esterified to the sn-2 position of phospholipids such as PAF and particular oxidatively fragmented phospholipids. Treatment of MM-LDL with PAF-AH (2-4 x 10(-2) U/ml) eliminated the ability of MM-LDL to induce endothelial cells to bind monocytes. When HDL protected against the formation of MM-LDL by cocultures, lysophosphatidylcholine was detected in HDL; whereas when HDL was pretreated with diisopropyl fluorophosphate, HDL was no longer protective and lysophosphatidylcholine was undetectable. HPLC analysis also revealed that the active oxidized phospholipid species in MM-LDL had been destroyed after PAF-AH treatment. In addition, treatment of MM-LDL with albumin removed polar phospholipids that, when reisolated, induced monocyte binding to endothelial cells. These polar phospholipids, when treated with PAF-AH, lost biological activity and were no longer detected by HPLC. These results suggest that PAF-AH in HDL protects against the production and activity of MM-LDL by facilitating hydrolysis of active oxidized phospholipids to lysolipids, thereby destroying the biologically active lipids in MM-LDL. PMID:7860760

  13. Senescence-induced ectopic expression of the A. tumefaciens ipt gene in wheat delays leaf senescence, increases cytokinin content, nitrate influx, and nitrate reductase activity, but does not affect grain yield.

    PubMed

    Sykorová, Blanka; Kuresová, Gabriela; Daskalova, Sasha; Trcková, Marie; Hoyerová, Klára; Raimanová, Ivana; Motyka, Václav; Trávnícková, Alena; Elliott, Malcolm C; Kamínek, Miroslav

    2008-01-01

    The manipulation of cytokinin levels by senescence-regulated expression of the Agrobacterium tumefaciens ipt gene through its control by the Arabidopsis SAG12 (senescence-associated gene 12) promoter is an efficient tool for the prolongation of leaf photosynthetic activity which potentially can affect plant productivity. In the present study, the efficiency of this approach was tested on wheat (Triticum aestivum L.)-a monocarpic plant characterized by a fast switch from vegetative to reproductive growth, and rapid translocation of metabolites from leaves to developing grains after anthesis. When compared with the wild-type (WT) control plants, the SAG12::ipt wheat plants exhibited delayed chlorophyll degradation only when grown under limited nitrogen (N) supply. Ten days after anthesis the content of chlorophyll and bioactive cytokinins of the first (flag) leaf of the transgenic plants was 32% and 65% higher, respectively, than that of the control. There was a progressive increase in nitrate influx and nitrate reductase activity. However, the SAG12::ipt and the WT plants did not show differences in yield-related parameters including number of grains and grain weight. These results suggest that the delay of leaf senescence in wheat also delays the translocation of metabolites from leaves to developing grains, as indicated by higher accumulation of ((15)N-labelled) N in spikes of control compared with transgenic plants prior to anthesis. This delay interferes with the wheat reproductive strategy that is based on a fast programmed translocation of metabolites from the senescing leaves to the reproductive sinks shortly after anthesis.

  14. Influence of Body Composition, Oral Contraceptive Use, and Physical Activity on Bone Mineral Density in Premenopausal Women.

    PubMed

    Sherk, Vanessa D; Howard, Clint D; Bemben, Michael G; Bemben, Debra A

    In premenopausal women, low bone density may reflect attainment of a lower peak bone mass which can increase risk of osteoporosis after menopause. The purpose of this study was to examine the relationship between total body, lumbar spine, and proximal femur bone mineral density (BMD) and body composition and oral contraceptive (OC) use in 18-30 year old women. Sixty-five healthy women, split into groups of oral contraceptive users (OC, n = 36) and non oral contraceptive users (Non-OC, n = 29), completed Baecke physical activity, calcium intake, and menstrual history questionnaires. Total body, AP lumbar spine, and dual proximal femur scans were performed using Dual Energy X-Ray Absorptiometry (DXA). Body composition measures were obtained from the total body scan analysis. No significant differences were found for BMD in OC users and non-users. Bone free lean body mass (BFLBM) and weight were positively correlated to all BMD sites, and fat mass was related to total body and L1-L4 spine BMD (p < 0.05). Stepwise regression analyses determined that weight was a significant predictor for all BMD sites (p < 0.05). When separating the two components of body weight, BFLBM was a significant predictor for all BMD sites, and fat mass only predicted total body BMD. In conclusion, this study indicates that weight and BFLBM are significant contributors to BMD in young healthy premenopausal women, and OC use did not influence the relationship between BMD and BFLBM.

  15. Effects of Season and Host Physiological State on the Diversity, Density, and Activity of the Arctic Ground Squirrel Cecal Microbiota

    PubMed Central

    Stevenson, Timothy J.; Duddleston, Khrystyne N.

    2014-01-01

    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

  16. Optimizations of particle size and pulp density for solubilization of rock phosphate by a microbial consortium from activated sludge.

    PubMed

    Xiao, Chunqiao; Wu, Xiaoyan; Liu, Tingting; Xu, Guang; Chi, Ruan

    2016-12-29

    Microbial solubilization of rock phosphate is getting more and more attention recently. However, the microorganisms used in previous studies were mostly single or known species, and seldom studies focused on the mixed microorganisms or microbial consortia from natural environments. In this study, a microbial consortium taken from activated sludge was used to solubilize two different mid-low-grade rock phosphates. The results showed that the microbial consortium could effectively solubilize the rock phosphates in National Botanical Research Institute's phosphate growth medium and released soluble phosphorus in the broth. The biomass increased gradually, whereas the pH decreased sharply during the solubilizing process. The maximum phosphorus solubilization was recorded at particle size of 150 µm. Higher or lower than this optimal particle size, the phosphorus solubilization decreased. The phosphorus solubilization gradually decreased with a larger pulp density from 1 to 5%, and the optimal pulp density was 1%. The solubilization level of microbial consortium varied with different rock phosphates. The results revealed that the soluble phosphorus released from high-silicon ore was higher than which from high-magnesium ore. A strong positive correlation between biomass and phosphorus solubilization in the broth was observed from regression analysis results, and the phosphorus solubilization also had a significant negative correlation with pH in the broth.

  17. 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.

  18. Electron density and height at the F 1 region minimum gradient at low solar activity for an equatorial station

    NASA Astrophysics Data System (ADS)

    Adeniyi, J. O.; Radicella, Sandro M.

    1997-09-01

    The presence of a ledge of ionization between the E and F2 laver maximum electron density, either with a distinct critical frequency (fOF1) or in the form of an inflection point, is found to be a persistent feature of the equatorial ionosphere from 0700 to 1800 LT at low solar activity. The electron density NF1, and the height hF1, at the position of minimum gradient in ionospheric profiles were investigated for Ouagadougou, Burkina Faso, an equatorial station. NF1 was found to exhibit a clear diurnal variation, which depends on solar zenith angle (x). The cos(x) power was found to be 0.34. An obvious seasonal variation in NF1 was not found. The height hF1 shows neither a diurnal nor seasonal dependence, and has an average value of (166 ± 6) km. NF1 and hF1 were compared at 1000, 1200 and 1400 LT in the months of January and July, for Ouagadougou and Ibadan, Nigeria, another equatorial station. The comparison shows that there is no significant difference in hF1 for both stations, but some differences were found in NF1.

  19. 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

    2016-06-03

    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.

  20. Geomorphological activity at a rock glacier front detected with a 3D density-based clustering algorithm

    NASA Astrophysics Data System (ADS)

    Micheletti, Natan; Tonini, Marj; Lane, Stuart N.

    2017-02-01

    Acquisition of high density point clouds using terrestrial laser scanners (TLSs) has become commonplace in geomorphic science. The derived point clouds are often interpolated onto regular grids and the grids compared to detect change (i.e. erosion and deposition/advancement movements). This procedure is necessary for some applications (e.g. digital terrain analysis), but it inevitably leads to a certain loss of potentially valuable information contained within the point clouds. In the present study, an alternative methodology for geomorphological analysis and feature detection from point clouds is proposed. It rests on the use of the Density-Based Spatial Clustering of Applications with Noise (DBSCAN), applied to TLS data for a rock glacier front slope in the Swiss Alps. The proposed methods allowed the detection and isolation of movements directly from point clouds which yield to accuracies in the following computation of volumes that depend only on the actual registered distance between points. We demonstrated that these values are more conservative than volumes computed with the traditional DEM comparison. The results are illustrated for the summer of 2015, a season of enhanced geomorphic activity associated with exceptionally high temperatures.

  1. Insecticidal activity of Ageratum conyzoides L., Coleus aromaticus Benth. and Hyptis suaveolens (L.) Poit essential oils as fumigant against storage grain insect Tribolium castaneum Herbst.

    PubMed

    Jaya; Singh, Priyanka; Prakash, Bhanu; Dubey, N K

    2014-09-01

    Essential oils (EOs) from Ageratum conyzoides L., Coleus aromaticus Benth. and Hyptis suaveolens (L.) Poit were extracted and tested against Tribolium castaneum Herbst, the storage grain insect. The EOs were found effective against Tribolium castaneum during in vitro as well as in vivo fumigant testing. The EOs of H. suaveolens and A. conyzoides showed 100 % mortality of test insect at 250 ppm while C. aromaticus at 350 ppm. During in vivo fumigant testing of wheat samples against Tribolium castaneum, the essential oils of A. conyzoides and C. aromaticus completely checked the damage of wheat grains by the insect at 1000 ppm while essential oil of H. suaveolens checked the grain damage completely even at 500 ppm concentration. There was no adverse effect on seed germination as well as on seedling growth of EOs treated seeds showing non-phytotoxic nature of the oils. Hence, these EOs may be recommended as botanical insecticide against insect invasion of stored food commodities, thereby enhancing their shelf life.

  2. Connectivity between electrical conduction and thermally activated grain size evolution in Ho-doped CoFe2O4 ferrite

    NASA Astrophysics Data System (ADS)

    Panneer Muthuselvam, I.; Bhowmik, R. N.

    2010-11-01

    Ho-doped CoFe2O4 spinel ferrite has been synthesized by a combination of mechanical alloying and subsequent annealing of the alloyed powder in the temperature range 950 °C <= TAN <= 1200 °C. The grains of the nanocrystalline samples have been found in the single domain/pseudo-single domain state for TAN <= 1050 °C and multi-domain state for TAN >= 1100 °C. The room temperature Fourier transform infrared spectroscopy spectrum of the samples indicated substantial changes in the tetrahedral sites of the cubic spinel structure while the alloyed powder was annealed at different temperatures. Ac conductivity of the nano-grained samples has been studied in the frequency range 1 Hz-3 MHz and temperature range 303-523 K. This work has been specifically designed to highlight the properties of electrical conductivity in the annealed samples. Experimental results revealed a strong connectivity between electrical conduction and the single domain and multi-domain states of the grains.

  3. Understanding the conformational flexibility and electrostatic properties of curcumin in the active site of rhAChE via molecular docking, molecular dynamics, and charge density analysis.

    PubMed

    Saravanan, Kandasamy; Kalaiarasi, Chinnasamy; Kumaradhas, Poomani

    2017-01-04

    Acetylcholinesterase (AChE) is an important enzyme responsible for Alzheimer's disease, as per report, keto-enol form of curcumin inhibits this enzyme. The present study aims to understand the binding mechanism of keto-enol curcumin with the recombinant human Acetylcholinesterase (rhAChE) from its conformational flexibility, intermolecular interactions, charge density distribution, and the electrostatic properties at the active site of rhAChE. To accomplish this, a molecular docking analysis of curcumin with the rhAChE was performed, which gives the structure and conformation of curcumin in the active site of rhAChE. Further, the charge density distribution and the electrostatic properties of curcumin molecule (lifted from the active site of rhAChE) were determined from the high level density functional theory (DFT) calculations coupled with the charge density analysis. On the other hand, the curcumin molecule was optimized (gas phase) using DFT method and further, the structure and charge density analysis were also carried out. On comparing the conformation, charge density distribution and the electrostatic potential of the active site form of curcumin with the corresponding gas phase form reveals that the above said properties are significantly altered when curcumin is present in the active site of rhAChE. The conformational stability and the interaction of curcumin in the active site are also studied using molecular dynamics simulation, which shows a large variation in the conformational geometry of curcumin as well as the intermolecular interactions.

  4. 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.

  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. 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.

  7. 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.

  8. Para-aminobenzamidine linked regenerated cellulose membranes for plasminogen activator purification: effect of spacer arm length and ligand density.

    PubMed

    Fasoli, Ezio; Reyes, Yiaslin Ruiz; Guzman, Osiris Martinez; Rosado, Alexandra; Cruz, Vivian Rodriguez; Borges, Amaris; Martinez, Edmarie; Bansal, Vibha

    2013-07-01

    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 (5-25nmol/cm(2)). 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 nmoles 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 mono-component 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±1.0nmol/cm(2)) 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.

  9. 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.

  10. Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model.

    PubMed

    Fitzgerald, James E; Robinson, Robert L; Gasem, Khaled 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 CO2 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 CO2 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 CO2 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.

  11. Saturation deficit and deer density affect questing activity and local abundance of Ixodes ricinus (Acari, Ixodidae) in Italy.

    PubMed

    Tagliapietra, V; Rosà, R; Arnoldi, D; Cagnacci, F; Capelli, G; Montarsi, F; Hauffe, H C; Rizzoli, A

    2011-12-29

    The wood tick Ixodes ricinus, one of the most common arthropod-borne disease vectors, is of increasing relevance for human and animal health in Europe. The aim of this study was to determine the relative contribution of several abiotic and biotic factors potentially affecting questing activity and local abundance of I. ricinus in Italy, considering the scale at which these factors interact with the host-seeking ticks. Within EDEN, a large-scale EU collaborative project on eco-epidemiology of vector-borne diseases, we collected questing ticks for three consecutive years using a standard protocol at eleven sites in the Italian Alps and Apennines. A total of 25 447 I. ricinus were collected. All sites showed the same annual pattern of tick activity (bimodal for nymphs and unimodal for larvae and adults), although the abundance of nymphs was statistically different between sites and years. A Generalized Linear Mixed Model and a Linear Mixed Model fitted to data for nymphs, showed that while the principal variables affecting the local abundance of questing ticks were saturation deficit (an index combining temperature and relative humidity) and red deer density, the most important variable affecting questing nymph activity was saturation deficit. As for the timing of seasonal emergence, we confirmed that the threshold temperature at this latitude for larvae is 10°C (mean maximum) while that for nymphs is 8°C.

  12. 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.

  13. 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 th