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Sample records for ag volume fraction

  1. Soot Volume Fraction Imaging

    NASA Technical Reports Server (NTRS)

    Greenberg, Paul S.; Ku, Jerry C.

    1994-01-01

    A new technique is described for the full-field determination of soot volume fractions via laser extinction measurements. This technique differs from previously reported point-wise methods in that a two-dimensional array (i.e., image) of data is acquired simultaneously. In this fashion, the net data rate is increased, allowing the study of time-dependent phenomena and the investigation of spatial and temporal correlations. A telecentric imaging configuration is employed to provide depth-invariant magnification and to permit the specification of the collection angle for scattered light. To improve the threshold measurement sensitivity, a method is employed to suppress undesirable coherent imaging effects. A discussion of the tomographic inversion process is provided, including the results obtained from numerical simulation. Results obtained with this method from an ethylene diffusion flame are shown to be in close agreement with those previously obtained by sequential point-wise interrogation.

  2. Volume Fraction Effects in Electroacoustic Measurements.

    PubMed

    Rasmusson, Mikael

    2001-08-15

    We measured the dynamic mobility of a polystyrene latex at 1 MHz as a function of volume fraction using the ESA-8000. The volume fraction dependence is compared with a semiempirical equation as well as with some theoretical predictions. It turns out that our polystyrene latex exhibits a volume fraction dependence much weaker than that predicted by any of the theories. This suggests that (polystyrene) latices may not be the ideal model system and that the centrifugation process may influence the surface structure of the particles. We also measured the dynamic mobility spectrum of a silica sol as a function of volume fraction using the Acoustosizer. The experimental spectrum of the silica sol was found to agree reasonably well with the semiempirical and theoretical spectra, especially below φ=0.144. At higher volume fractions we observed positive phase angles that were not predicted by the semiempirical method nor the cell model. Copyright 2001 Academic Press. PMID:11482951

  3. Absorbed fractions for electrons in ellipsoidal volumes.

    PubMed

    Amato, E; Lizio, D; Baldari, S

    2011-01-21

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as (90)Y and to (131)I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  4. Absorbed fractions for electrons in ellipsoidal volumes

    NASA Astrophysics Data System (ADS)

    Amato, E.; Lizio, D.; Baldari, S.

    2011-01-01

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  5. Lamb Wave Assessment of Fiber Volume Fraction in Composites

    NASA Technical Reports Server (NTRS)

    Seale, Michael D.; Smith, Barry T.; Prosser, W. H.; Zalameda, Joseph N.

    1998-01-01

    Among the various techniques available, ultrasonic Lamb waves offer a convenient method of examining composite materials. Since the Lamb wave velocity depends on the elastic properties of a material, an effective tool exists to evaluate composites by measuring the velocity of these waves. Lamb waves can propagate over long distances and are sensitive to the desired in-plane elastic properties of the material. This paper discusses a study in which Lamb waves were used to examine fiber volume fraction variations of approximately 0.40-0.70 in composites. The Lamb wave measurements were compared to fiber volume fractions obtained from acid digestion tests. Additionally, a model to predict the fiber volume fraction from Lamb wave velocity values was evaluated.

  6. Method and apparatus for probing relative volume fractions

    DOEpatents

    Jandrasits, W.G.; Kikta, T.J.

    1998-03-17

    A relative volume fraction probe particularly for use in a multiphase fluid system includes two parallel conductive paths defining therebetween a sample zone within the system. A generating unit generates time varying electrical signals which are inserted into one of the two parallel conductive paths. A time domain reflectometer receives the time varying electrical signals returned by the second of the two parallel conductive paths and, responsive thereto, outputs a curve of impedance versus distance. An analysis unit then calculates the area under the curve, subtracts the calculated area from an area produced when the sample zone consists entirely of material of a first fluid phase, and divides this calculated difference by the difference between an area produced when the sample zone consists entirely of material of the first fluid phase and an area produced when the sample zone consists entirely of material of a second fluid phase. The result is the volume fraction. 9 figs.

  7. Method and apparatus for probing relative volume fractions

    DOEpatents

    Jandrasits, Walter G.; Kikta, Thomas J.

    1998-01-01

    A relative volume fraction probe particularly for use in a multiphase fluid system includes two parallel conductive paths defining therebetween a sample zone within the system. A generating unit generates time varying electrical signals which are inserted into one of the two parallel conductive paths. A time domain reflectometer receives the time varying electrical signals returned by the second of the two parallel conductive paths and, responsive thereto, outputs a curve of impedance versus distance. An analysis unit then calculates the area under the curve, subtracts the calculated area from an area produced when the sample zone consists entirely of material of a first fluid phase, and divides this calculated difference by the difference between an area produced when the sample zone consists entirely of material of the first fluid phase and an area produced when the sample zone consists entirely of material of a second fluid phase. The result is the volume fraction.

  8. Nuclear Volume-Dependent Fractionation of Uranium Isotopes

    NASA Astrophysics Data System (ADS)

    Weyer, S.; Schauble, E. A.; Anbar, A. D.

    2007-12-01

    Chemical reactions can fractionate isotopes because the magnitudes of equilibrium and rate constants are subtly sensitive to nuclear mass. Geoscientists have exploited this fact to learn about modern environmental processes and past environmental conditions by precisely measuring variations in the isotope compositions of a wide range of elements in natural materials. Here we present evidence from natural terrestrial samples that processes related to ¡°nuclear volume¡± rather than ¡°nuclear mass¡± significantly fractionate the isotope composition of the heaviest primordial element ¨C uranium. The isotopic composition of U in nature is generally assumed to be invariant. Here, we report variations of the 238U/235U isotope ratio in natural samples (basalts, granites, seawater, corals, black shales, suboxic sediments, ferro-manganese crusts/nodules and BIFs), which span a range of δ238U values of ~ 1.3 ‰, exceeding by far the analytical precision of our method (¡Ö 0.06‰, 2SD, based on replicate measurements of individual samples). The largest isotope variations found in our survey are between oxidized and reduced depositional environments, with seawater and suboxic sediments falling in between. U isotopes were analyzed with MC-ICP-MS. A mixed 236U-233U isotopic tracer (double spike) was used to correct for isotope fractionation during sample purification and instrumental mass bias. Sediments formed in oxic environments, such as manganese crusts from the Atlantic and Pacific oceans, display δ238U of -0.54 to -0.62 ‰, slightly lighter than that of seawater (-0.41 ‰). However, sediments from reducing environments, such as black shales from the Black Sea (unit I and unit II) and the Cariaco basin, display heavy U isotope compositions with δ238U of up to +0.43 ‰ (0.84 ‰ heavier than seawater). Uranium enrichment in these sediments probably occurred during the reduction of soluble U(VI) (from seawater) to insoluble U(IV). Intriguingly, isotope

  9. VOFI - A library to initialize the volume fraction scalar field

    NASA Astrophysics Data System (ADS)

    Bnà, S.; Manservisi, S.; Scardovelli, R.; Yecko, P.; Zaleski, S.

    2016-03-01

    The VOFI library has been developed to accurately calculate the volume fraction field demarcated by implicitly-defined fluid interfaces in Cartesian grids with cubic cells. The method enlists a number of algorithms to compute the integration limits and the local height function, that is the integrand of a double Gauss-Legendre integration with a variable number of nodes. Tests in two and three dimensions are presented to demonstrate the accuracy of the method and are provided in the software distribution with C/C++ and FORTRAN interfaces.

  10. Effect of volume fraction on granular avalanche dynamics.

    PubMed

    Gravish, Nick; Goldman, Daniel I

    2014-09-01

    We study the evolution and failure of a granular slope as a function of prepared volume fraction, ϕ(0). We rotated an initially horizontal layer of granular material (0.3-mm-diam glass spheres) to a 45° angle while we monitor the motion of grains from the side and top with high-speed video cameras. The dynamics of grain motion during the tilt process depended sensitively on ϕ(0)∈[0.58-0.63] and differed above or below the granular critical state, ϕ(c), defined as the onset of dilation as a function of increasing volume fraction. For ϕ(0)-ϕ(c)<0, slopes experienced short, rapid, precursor compaction events prior to the onset of a sustained avalanche. Precursor compaction events began at an initial angle θ(0)=7.7±1.4° and occurred intermittently prior to the onset of an avalanche. Avalanches occurred at the maximal slope angle θ(m)=28.5±1.0°. Granular material at ϕ(0)-ϕ(c)>0 did not experience precursor compaction prior to avalanche flow, and instead experienced a single dilational motion at θ(0)=32.1±1.5° prior to the onset of an avalanche at θ(m)=35.9±0.7°. Both θ(0) and θ(m) increased with ϕ(0) and approached the same value in the limit of random close packing. The angle at which avalanching grains came to rest, θ(R)=22±2°, was independent of ϕ(0). From side-view high-speed video, we measured the velocity field of intermittent and avalanching flow. We found that flow direction, depth, and duration were affected by ϕ(0), with ϕ(0)-ϕ(c)<0 precursor flow extending deeper into the granular bed and occurring more rapidly than precursor flow at ϕ(0)-ϕ(c)>0. Our study elucidates how initial conditions-including volume fraction-are important determinants of granular slope stability and the onset of avalanches. PMID:25314432

  11. Influence of volume fraction on the dynamics of granular impact

    NASA Astrophysics Data System (ADS)

    Umbanhowar, Paul; Yang, Ding; Goldman, Daniel

    2008-11-01

    Variation of the volume fraction φ of non-cohesive granular media causes disproportionate changes in the forces exerted on impacting objects and, consequently, the impact kinematics. In our experiments, a computer controlled air fluidized granular bed is used to vary φ from 0.58 (low) to 0.62 (high) for 0.3 mm diameter glass spheres and 1̃ mm poppy seeds. An accelerometer attached to a 4.0 cm diameter steel sphere measures collision forces for initial impact velocities ranging from 0.5 to 3.5 m/s. As an example of the dramatic changes produced by varying φ, time series of the force during impact with poppy seeds at an impact velocity of 1 m/s change from monotonically increasing with slope 100 N/s at φ=0.59 to monotonically decreasing with slope -100 N/s at φ=0.62; glass beads show similar behavior. Increasing φ from low to high at fixed collision velocity causes the penetration depth to decrease monotonically by approximately 50%. However, for the same parameters, the collision duration changes little, decreasing by 10% as φ is increased from 0.58 to 0.6 and then increasing by about 3% as φ is increased to 0.63. Our impact simulations exhibit the same collision dynamics vs. φ and reveal qualitative differences in grain velocity fields and local volume fraction changes between low and high φ states. Support by the Burroughs Wellcome Fund and the Army Research Lab MAST CTA.

  12. Extracellular volume fraction in coronary chronic total occlusion patients.

    PubMed

    Chen, Yin Yin; Zhang, Wei Guo; Yang, Shan; Yun, Hong; Deng, Sheng Ming; Fu, Cai Xia; Zeng, Meng Su; Jin, Hang; Guo, Liang

    2015-08-01

    (1) To assess extracellular volume fraction (ECV) and regional systolic function in patients presenting with coronary chronic total occlusion (CTO) in areas without significant late gadolinium enhancement (LGE), and (2) to investigate the correlation between angiography collateral flow and ECV in territories supplied by CTO vessels. A total of 50 angiographically documented CTO patients and 15 age- and sex-matched normal controls were recruited to the study. Myocardial ECV, was calculated in infarcted, global non-infarcted and the entire myocardium respectively. Segmental ECV was calculated from myocardial segments within the perfusion territory of a CTO vessel. The global and regional systolic function was evaluated using ejection fraction and percent systolic thickening. ECVs in global myocardium and global non-infarcted myocardium were significantly elevated in comparison with that in controls (29.1 ± 4.2% and 26.6 ± 2.6% vs. 23.3 ± 2.0%, all P < 0.005). Global ECV significantly correlated with LV ejection fraction (r = -0.56, P < 0.001) and ECV inversely correlated with systolic thickening in global non-infarcted myocardium (r = -0.31, P < 0.05). The lower segmental ECV was associated with the presence of well-developed collaterals (P = 0.004), and multivariate binary logistic analysis demonstrated that mean segmental ECV and course of disease were the independent discriminator of collateral flow with overall diagnostic accuracy of 74.4%. In patients with CTO, ECV is found to be increased beyond that observed with LGE, and correlates with LV regional wall motion abnormality, which appears to reflect diffuse myocardial fibrosis. Mean segmental ECV value, combined with course of disease, may serve as good predictors of collateral flow. PMID:25985941

  13. Effect of volume fraction on granular avalanche dynamics

    NASA Astrophysics Data System (ADS)

    Gravish, Nick; Goldman, Daniel I.

    2014-09-01

    We study the evolution and failure of a granular slope as a function of prepared volume fraction, ϕ0. We rotated an initially horizontal layer of granular material (0.3-mm-diam glass spheres) to a 45∘ angle while we monitor the motion of grains from the side and top with high-speed video cameras. The dynamics of grain motion during the tilt process depended sensitively on ϕ0∈[0.58-0.63] and differed above or below the granular critical state, ϕc, defined as the onset of dilation as a function of increasing volume fraction. For ϕ0-ϕc<0, slopes experienced short, rapid, precursor compaction events prior to the onset of a sustained avalanche. Precursor compaction events began at an initial angle θ0=7.7±1.4∘ and occurred intermittently prior to the onset of an avalanche. Avalanches occurred at the maximal slope angle θm=28.5±1.0∘. Granular material at ϕ0-ϕc>0 did not experience precursor compaction prior to avalanche flow, and instead experienced a single dilational motion at θ0=32.1±1.5∘ prior to the onset of an avalanche at θm=35.9±0.7∘. Both θ0 and θm increased with ϕ0 and approached the same value in the limit of random close packing. The angle at which avalanching grains came to rest, θR=22±2∘, was independent of ϕ0. From side-view high-speed video, we measured the velocity field of intermittent and avalanching flow. We found that flow direction, depth, and duration were affected by ϕ0, with ϕ0-ϕc<0 precursor flow extending deeper into the granular bed and occurring more rapidly than precursor flow at ϕ0-ϕc>0. Our study elucidates how initial conditions—including volume fraction—are important determinants of granular slope stability and the onset of avalanches.

  14. Coarsening in high volume fraction nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Nathal, M. V.

    1990-01-01

    The coarsening behavior of the gamma-prime precipitate has been examined in high volume fraction nickel-base alloys aged at elevated temperatures for times of up to 5000 h. Although the cube rate law was observed during coarsening, none of the presently available coarsening theories showed complete agreement with the experimental particle size distributions (PSDs). These discrepancies were thought to be due to elastic coherency strains which were not considered by the available models. Increasing the Mo content significantly influenced the PSDs and decreased the coarsening rate of the gamma-prime cubes, as a result of increasing the magnitude of the lattice mismatch. After extended aging times, the gamma-prime cubes underwent massive coalescence into plates at a rate which was much faster than the cuboidal coarsening rate. Once the gamma-prime plates were formed, further coarsening was not observed, and this stabilization of the microstructure was attributed to the development of dislocation networks at the gamma-gamma-prime interfaces.

  15. Accuracy of cancellous bone volume fraction measured by micro-CT scanning.

    PubMed

    Ding, M; Odgaard, A; Hvid, I

    1999-03-01

    Volume fraction, the single most important parameter in describing trabecular microstructure, can easily be calculated from three-dimensional reconstructions of micro-CT images. This study sought to quantify the accuracy of this measurement. One hundred and sixty human cancellous bone specimens which covered a large range of volume fraction (9.8-39.8%) were produced. The specimens were micro-CT scanned, and the volume fraction based on Archimedes' principle was determined as a reference. After scanning, all micro-CT data were segmented using individual thresholds determined by the scanner supplied algorithm (method I). A significant deviation of volume fraction from method I was found: both the y-intercept and the slope of the regression line were significantly different from those of the Archimedes-based volume fraction (p < 0.001). New individual thresholds were determined based on a calibration of volume fraction to the Archimedes-based volume fractions (method II). The mean thresholds of the two methods were applied to segment 20 randomly selected specimens. The results showed that volume fraction using the mean threshold of method I was underestimated by 4% (p = 0.001), whereas the mean threshold of method II yielded accurate values. The precision of the measurement was excellent. Our data show that care must be taken when applying thresholds in generating 3-D data, and that a fixed threshold may be used to obtain reliable volume fraction data. This fixed threshold may be determined from the Archimedes-based volume fraction of a subgroup of specimens. The threshold may vary between different materials, and so it should be determined whenever a study series is performed. PMID:10093033

  16. Iodization of rf sputter induced disordered Ag thin films reveals volume plasmon-exciton 'transition'

    SciTech Connect

    Bharathi Mohan, D.; Sunandana, C. S.

    2006-09-15

    Quasiamorphous Ag films of thicknesses ranging from 5 to 30 nm were prepared using rf magnetron sputtering technique and their controlled iodization was carried out for selected durations in the range of 15 min-60 h at room temperature. As deposited Ag and iodized films were characterized using x-ray diffraction (XRD), atomic force microscope (AFM), and optical absorption techniques. From XRD, {gamma} and {beta}+{gamma} (mixed) phases of AgI nanoparticles have been observed for 5-10 and 20-30 nm thick films, respectively. Lattice parameters (a and c) and average strain ({epsilon}) were calculated versus iodization time for {gamma} and {beta}-AgI nanoparticles. Uniform and nonuniform spherically shaped AgI nanoparticles ({approx}20-130 nm) are realized through AFM for 5-10 and 20-30 nm thick films. Optical absorption shows volume plasmons (classified as PR1) for short duration iodization, which ''decay'' upon further iodization to convert to Z{sub 1,2} and Z{sub 3} excitons at 420 and 330 nm, respectively, in the manner of a metal-semiconductor/dielectric phase transition. Ag 'colloidal' particles (classified as PR2) are formed for 5-10 nm thick films and thereby control the {gamma} phase--a significant and applicable effect attributed to critical film thickness. With increasing thickness, a surface strain field lifting the degeneracy of the valence band results in Z{sub 1,2} and Z{sub 3} exciton formation at room temperature. Blueshift in the exciton absorption with decreasing film thickness implies the progressive quantum confinement due to decrease in the particle size. A thickness induced phase transition from {gamma}-AgI to {beta}-AgI is discussed by means of x-ray diffraction and optical absorption studies.

  17. Modeling of soft interfacial volume fraction in composite materials with complex convex particles.

    PubMed

    Xu, Wenxiang; Chen, Wen; Chen, Huisu

    2014-01-21

    The influence of the soft interfacial volume fraction on physical properties of composite materials has been found to be significant. However, the soft interfacial volume fraction is difficultly determined by traditional experimental methods and simple models proposed so far. This article addresses the problem by means of theoretical and numerical approaches that start at a microscopic scale of composite materials, which are regarded as a three-phase composite structure with polydisperse convex particles, soft interfaces, and a matrix. A theoretical scheme for the soft interfacial volume fraction is proposed by a theory of the nearest-surface distribution functions and geometrical configurations of polydisperse convex particles. The theoretical scheme represents a generalized model for the soft interfacial volume fraction in that it cannot only determine the interfacial volume fraction around convex polyhedral particles but also to derive that around ellipsoidal and spherical particles. In order to test the theoretical scheme, a numerical model that adopts the three-phase composite structure and a numerical Monte Carlo integration scheme is presented. Also, theoretical and numerical results of the soft interfacial volume fraction around ellipsoidal and spherical particles in the literature are further compared. By way of application, it is shown that the developed model provides a quantitative means to evaluate the dependence of the soft interfacial volume fraction on various factors, such as geometrical configurations of particles and the interfacial thickness.

  18. Imaging air volume fraction in sea ice using non-destructive X-ray tomography

    NASA Astrophysics Data System (ADS)

    Crabeck, Odile; Galley, Ryan; Delille, Bruno; Else, Brent; Geilfus, Nicolas-Xavier; Lemes, Marcos; Des Roches, Mathieu; Francus, Pierre; Tison, Jean-Louis; Rysgaard, Søren

    2016-05-01

    Although the presence of a gas phase in sea ice creates the potential for gas exchange with the atmosphere, the distribution of gas bubbles and transport of gases within the sea ice are still poorly understood. Currently no straightforward technique exists to measure the vertical distribution of air volume fraction in sea ice. Here, we present a new fast and non-destructive X-ray computed tomography technique to quantify the air volume fraction and produce separate images of air volume inclusions in sea ice. The technique was performed on relatively thin (4-22 cm) sea ice collected from an experimental ice tank. While most of the internal layers showed air volume fractions < 2 %, the ice-air interface (top 2 cm) systematically showed values up to 5 %. We suggest that the air volume fraction is a function of both the bulk ice gas saturation factor and the brine volume fraction. We differentiate micro bubbles (Ø < 1 mm), large bubbles (1 mm < Ø < 5 mm) and macro bubbles (Ø > 5 mm). While micro bubbles were the most abundant type of gas bubbles, most of the air porosity observed resulted from the presence of large and macro bubbles. The ice texture (granular and columnar) as well as the permeability state of ice are important factors controlling the air volume fraction. The technique developed is suited for studies related to gas transport and bubble migration.

  19. Variability in the fractionation of Cu, Ag, and Zn among cytosolic proteins in the bivalve Macoma balthica

    USGS Publications Warehouse

    Johansson, C.; Cain, Daniel J.; Luoma, Samuel N.

    1986-01-01

    Gel filtration chromatographs of cytosols from the clam Macorna balthica analysed from both field and laboratory treated specimens showed that uptake of Cu, Ag, and Zn in the metallothionein-like protein (MLP) pool follows exposure both in nature and in the laboratory. Specimens collected from San Francisco Bay over 18 mo showed strong temporal variability in the fractionation of the metals among cytosolic proteins. A marked increase in Cu, Ag, and Zn in a very low molecular weight pool occurred when concentrations were highest In the MLP pool. The correlation between total cytosollc metal and MLP-metal also appeared to approach a hyperbolic character at the highest concentrations.

  20. Inter-Fraction Tumor Volume Response during Lung Stereotactic Body Radiation Therapy Correlated to Patient Variables

    PubMed Central

    Ayan, Ahmet S.; Mo, Xiaokui; Williams, Terence M.; Mayr, Nina A.; Grecula, John C.; Chakravarti, Arnab; Xu-Welliver, Meng

    2016-01-01

    Purpose Analyze inter-fraction volumetric changes of lung tumors treated with stereotactic body radiation therapy (SBRT) and determine if the volume changes during treatment can be predicted and thus considered in treatment planning. Methods and Materials Kilo-voltage cone-beam CT (kV-CBCT) images obtained immediately prior to each fraction were used to monitor inter-fraction volumetric changes of 15 consecutive patients (18 lung nodules) treated with lung SBRT at our institution (45–54 Gy in 3–5 fractions) in the year of 2011–2012. Spearman's (ρ) correlation and Spearman's partial correlation analysis was performed with respect to patient/tumor and treatment characteristics. Multiple hypothesis correction was performed using False Discovery Rate (FDR) and q-values were reported. Results All tumors studied experienced volume change during treatment. Tumor increased in volume by an average of 15% and regressed by an average of 11%. The overall volume increase during treatment is contained within the planning target volume (PTV) for all tumors. Larger tumors increased in volume more than smaller tumors during treatment (q = 0.0029). The volume increase on CBCT was correlated to the treatment planning gross target volume (GTV) as well as internal target volumes (ITV) (q = 0.0085 and q = 0.0039 respectively) and could be predicted for tumors with a GTV less than 22 mL. The volume increase was correlated to the integral dose (ID) in the ITV at every fraction (q = 0.0049). The peak inter-fraction volume occurred at an earlier fraction in younger patients (q = 0.0122). Conclusions We introduced a new analysis method to follow inter-fraction tumor volume changes and determined that the observed changes during lung SBRT treatment are correlated to the initial tumor volume, integral dose (ID), and patient age. Furthermore, the volume increase during treatment of tumors less than 22mL can be predicted during treatment planning. The volume increase remained

  1. Multilayer piezocomposite structures with piezoceramic volume fractions determined by mathematical optimisation.

    PubMed

    Abrar, A; Cochran, S

    2004-04-01

    Piezocomposite materials are now widely used in broadband underwater sonar for ultrasound generation and detection because of their recognised advantages over piezoceramic devices. However, it is difficult to make single-layer piezocomposite devices to operate effectively at frequencies below 100 kHz. Instead, multilayer composite stacks can be used. If this solution is adopted, interesting effects can be achieved by choosing appropriate ceramic volume fractions for different layers in the stack, as volume fraction plays a key role in achieving the desired performance. In this paper we describe a theoretical study of 1-3 piezocomposite transducers with five layers each with a different volume fraction. Our work is based mainly on our own special purpose computer code which solves the one-dimensional wave equation by matrix manipulation, with additional support from the PZ Flex finite element analysis package. The choice of volume fractions is difficult because of the multifaceted nature of the problem, with a very large number of possible combinations and complex dependence of material properties, and hence transducer sensitivity and frequency response on the volume fractions. Therefore, we have used the stochastic optimisation technique of simulated annealing implemented in MATLAB code to determine the volume fraction of each layer. The optimisation cost function we have used is maximisation of gain-bandwidth product. We have found that significant increases in gain-bandwidth product can be achieved compared with the use of the same volume fraction in each layer, far exceeding the 35% reported previously with trial-and-error volume fraction adjustment. This suggests that improvements in practical device performance are possible.

  2. Correlation of cell volume fractions with cell concentrations in fermentation media.

    PubMed

    Ju, L K; Ho, C S

    1988-06-20

    Cell volume fractions and cell concentrations were measured in submerged cultures of Saccharomyces cerevisiae, Escherichia coli, and Penicillium chrysogenum. Correlations for cell volume fractions with cell concentrations in fermentation media of the microorganisms were established accordingly. Other key properties of microorganisms, such as cell water content, wet cell density, and dry cell density, can also be obtained with the use of the current method. The results are in good agreement with data available in the literature.

  3. The optimal fiber volume fraction and fiber-matrix property compatibility in fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Pan, Ning

    1992-01-01

    Although the question of minimum or critical fiber volume fraction beyond which a composite can then be strengthened due to addition of fibers has been dealt with by several investigators for both continuous and short fiber composites, a study of maximum or optimal fiber volume fraction at which the composite reaches its highest strength has not been reported yet. The present analysis has investigated this issue for short fiber case based on the well-known shear lag (the elastic stress transfer) theory as the first step. Using the relationships obtained, the minimum spacing between fibers is determined upon which the maximum fiber volume fraction can be calculated, depending on the fiber packing forms within the composites. The effects on the value of this maximum fiber volume fraction due to such factors as fiber and matrix properties, fiber aspect ratio and fiber packing forms are discussed. Furthermore, combined with the previous analysis on the minimum fiber volume fraction, this maximum fiber volume fraction can be used to examine the property compatibility of fiber and matrix in forming a composite. This is deemed to be useful for composite design. Finally some examples are provided to illustrate the results.

  4. Fractional volume integration in two-dimensional NMR spectra: CAKE, a Monte Carlo approach.

    PubMed

    Romano, Rocco; Paris, Debora; Acernese, Fausto; Barone, Fabrizio; Motta, Andrea

    2008-06-01

    Quantitative information from multi-dimensional NMR experiments can be obtained by peak volume integration. The standard procedure (selection of a region around the chosen peak and addition of all values) is often biased by poor peak definition because of peak overlap. Here we describe a simple method, called CAKE, for volume integration of (partially) overlapping peaks. Assuming the axial symmetry of two-dimensional NMR peaks, as it occurs in NOESY and TOCSY when Lorentz-Gauss transformation of the signals is carried out, CAKE estimates the peak volume by multiplying a volume fraction by a factor R. It represents a proportionality ratio between the total and the fractional volume, which is identified as a slice in an exposed region of the overlapping peaks. The volume fraction is obtained via Monte Carlo Hit-or-Miss technique, which proved to be the most efficient because of the small region and the limited number of points within the selected area. Tests on simulated and experimental peaks, with different degrees of overlap and signal-to-noise ratios, show that CAKE results in improved volume estimates. A main advantage of CAKE is that the volume fraction can be flexibly chosen so as to minimize the effect of overlap, frequently observed in two-dimensional spectra. PMID:18396078

  5. Fractional volume integration in two-dimensional NMR spectra: CAKE, a Monte Carlo approach

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Paris, Debora; Acernese, Fausto; Barone, Fabrizio; Motta, Andrea

    2008-06-01

    Quantitative information from multi-dimensional NMR experiments can be obtained by peak volume integration. The standard procedure (selection of a region around the chosen peak and addition of all values) is often biased by poor peak definition because of peak overlap. Here we describe a simple method, called CAKE, for volume integration of (partially) overlapping peaks. Assuming the axial symmetry of two-dimensional NMR peaks, as it occurs in NOESY and TOCSY when Lorentz-Gauss transformation of the signals is carried out, CAKE estimates the peak volume by multiplying a volume fraction by a factor R. It represents a proportionality ratio between the total and the fractional volume, which is identified as a slice in an exposed region of the overlapping peaks. The volume fraction is obtained via Monte Carlo Hit-or-Miss technique, which proved to be the most efficient because of the small region and the limited number of points within the selected area. Tests on simulated and experimental peaks, with different degrees of overlap and signal-to-noise ratios, show that CAKE results in improved volume estimates. A main advantage of CAKE is that the volume fraction can be flexibly chosen so as to minimize the effect of overlap, frequently observed in two-dimensional spectra.

  6. Fractional volume integration in two-dimensional NMR spectra: CAKE, a Monte Carlo approach

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Paris, Debora; Motta, Andrea; Barone, Fabrizio

    2009-03-01

    Quantitative information from multidimensional NMR experiments can be obtained by peak volume integration. The standard procedure (selection of a region around the chosen peak and addition of all values) is often biased by poor peak definition because of peak overlap. Here we describe a simple method, called CAKE, for volume integration of (partially) overlapping peaks. Assuming the axial symmetry of two-dimensional NMR peaks, as it occurs in NOESY and TOCSY when Lorentz-Gauss transformation of the signals is carried out, CAKE estimates the peak volume by multiplying a volume fraction by a factor R. It represents a proportionality ratio between the total and the fractional volume, which is identified as a slice in an exposed region of the overlapping peaks. The volume fraction is obtained via Monte Carlo Hit-or-Miss technique, which proved to be the most efficient because of the small region and the limited number of points within the selected area. Tests on simulated and experimental peaks, with different degrees of overlap and signal-to-noise ratios, show that CAKE results in improved volume estimates. A main advantage of CAKE is that the volume fraction can be flexibly chosen so as to minimize the effect of overlap, frequently observed in two-dimensional spectra.

  7. The coupled effect of fiber volume fraction and void fraction on hydraulic fluid absorption of quartz/BMI laminates

    NASA Astrophysics Data System (ADS)

    Hurdelbrink, Keith R.; Anderson, Jacob P.; Siddique, Zahed; Altan, M. Cengiz

    2016-03-01

    Bismaleimide (BMI) resin with quartz (AQ581) fiber reinforcement is a composite material frequently used in aerospace applications, such as engine cowlings and radomes. Various composite components used in aircrafts are exposed to different types of hydraulic fluids, which may lead to anomalous absorption behavior over the service life of the composite. Accurate predictive models for absorption of liquid penetrants are particularly important as the composite components are often exposed to long-term degradation due to absorbed moisture, hydraulic fluids, or similar liquid penetrants. Microstructural features such as fiber volume fraction and void fraction can have a significant effect on the absorption behavior of fiber-reinforced composites. In this paper, hydraulic fluid absorption characteristics of quartz/BMI laminates fabricated from prepregs preconditioned at different relative humidity and subsequently cured at different pressures are presented. The composite samples are immersed into hydraulic fluid at room temperature, and were not subjected to any prior degradation. To generate process-induced microvoids, prepregs were conditioned in an environmental chamber at 2% or 99% relative humidity at room temperature for a period of 24 hours prior to laminate fabrication. To alter the fiber volume fraction, the laminates were fabricated at cure pressures of 68.9 kPa (10 psi) or 482.6 kPa (70 psi) via a hot-press. The laminates are shown to have different levels of microvoids and fiber volume fractions, which were observed to affect the absorption dynamics considerably and exhibited clear non-Fickian behavior. A one-dimensional hindered diffusion model (HDM) was shown to be successful in predicting the hydraulic fluid absorption. Model prediction indicates that as the fabrication pressure increased from 68.9 kPa to 482.6 kPa, the maximum fluid content (M∞) decreased from 8.0% wt. to 1.0% wt. The degree of non-Fickian behavior, measured by hindrance coefficient (

  8. Effects of Retained Austenite Stability and Volume Fraction on Deformation Behaviors of TRIP Steels

    SciTech Connect

    Choi, Kyoo Sil; Soulami, Ayoub; Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.

    2010-10-02

    In this paper, the separate effects of austenite stability and its volume fraction on the deformation behaviors of transformation-induced plasticity (TRIP) steels are investigated based on the microstructure-based finite element modeling method. The effects of austenite stability on the strength, ductility and formability of TRIP steels are first examined based on the microstructure of a commercial TRIP 800 steel. Then, the separate effects of the austenite volume fraction on the overall deformation behaviors of TRIP steels are examined based on the various representative volume elements (RVEs). The computational results suggest that the higher austenite stability is helpful to increase the ductility and formability, but not the UTS. However, the increase of austenite volume fraction alone is not helpful in improving the performance of TRIP steels. This may indicate that various other material factors should also be concurrently adjusted during thermo-mechanical manufacturing process in a way to increase the performance of TRIP steels, which needs further investigation.

  9. In Situ Void Fraction and Gas Volume in Hanford Tank 241-SY-101 as Measured with the Void Fraction Instrument

    SciTech Connect

    CW Stewart; G Chen; JM Alzheimer; PA Meyer

    1998-11-10

    The void fraction instrument (WI) was deployed in Tank 241-SY-101 three times in 1998 to confm and locate the retained gas (void) postulated to be causing the accelerating waste level rise observed since 1995. The design, operation, and data reduction model of the WI are described along with validation testing and potential sources of uncertainty. The test plans, field observations and void measurements are described in detail, including the total gas volume calculations and the gas volume model. Based on 1998 data, the void fraction averaged 0.013 i 0.001 in the mixed slurry and 0.30 ~ 0.04 in the crust. This gives gas volumes (at standard pressure and temperature) of 87 t 9 scm in the slurry and 138 ~ 22 scm in the crust for a total retained gas volume of221 *25 scm. This represents an increase of about 74 scm in the crust and a decrease of about 34 scm in the slurry from 1994/95 results. The overall conclusion is that the gas retention is occurring mainly in the crust layer and there is very little gas in the mixed slurry and loosely settled layers below. New insights on crust behavior are also revealed.

  10. The relative impact of circumferential and longitudinal shortening on left ventricular ejection fraction and stroke volume

    PubMed Central

    MacIver, David H

    2012-01-01

    In vivo data have been unable to provide conclusive results with regard to the relative impact of circumferential and longitudinal shortening on stroke volume. The objective of the present study was to assess the relative contribution of circumferential and longitudinal myocardial shortening to left ventricular stroke volume and ejection fraction, and to evaluate the effect of left ventricular hypertrophy. A two-shell, three-dimensional mathematical model was used to assess the individual contributions of longitudinal and midwall circumferential shortening (or strain) to stroke volume and ejection fraction. Reducing either circumferential or longitudinal shortening resulted in a reduced ejection fraction and stroke volume. The stroke volume fell by 43% when circumferential strain was reduced from −20% to −5%, but only by 19% when longitudinal strain was similarly reduced. The sole contribution of circumferential and longitudinal shortening to stroke volume was 67% and 33%, respectively. These proportions were independent of wall thickness. The present study demonstrated that both longitudinal and midwall circumferential shortening contribute to different extents depending on the degree of abnormality of myocardial shortening. Contrary to most previous studies, the present study shows that circumferential shortening has a relatively greater contribution to stroke volume (ie, two-thirds) and ejection fraction than longitudinal shortening. These observations have important clinical and research implications in the assessment of left ventricular function. PMID:23204893

  11. Measuring local volume fraction, long-wavelength correlations, and fractionation in a phase-separating polydisperse fluid

    SciTech Connect

    Williamson, J. J.; Evans, R. M. L.

    2014-10-28

    We dynamically simulate fractionation (partitioning of particle species) during spinodal gas-liquid separation of a size-polydisperse colloid, using polydispersity up to ∼40% and a skewed parent size distribution. We introduce a novel coarse-grained Voronoi method to minimise size bias in measuring local volume fraction, along with a variety of spatial correlation functions which detect fractionation without requiring a clear distinction between the phases. These can be applied whether or not a system is phase separated, to determine structural correlations in particle size, and generalise easily to other kinds of polydispersity (charge, shape, etc.). We measure fractionation in both mean size and polydispersity between the phases, its direction differing between model interaction potentials which are identical in the monodisperse case. These qualitative features are predicted by a perturbative theory requiring only a monodisperse reference as input. The results show that intricate fractionation takes place almost from the start of phase separation, so can play a role even in nonequilibrium arrested states. The methods for characterisation of inhomogeneous polydisperse systems could in principle be applied to experiment as well as modelling.

  12. Volume fraction dependent magnetic behaviour of ferrofluids for rotating seal applications

    NASA Astrophysics Data System (ADS)

    Schinteie, G.; Palade, P.; Vekas, L.; Iacob, N.; Bartha, C.; Kuncser, V.

    2013-10-01

    Ferrofluid samples consisting of magnetite nanoparticles (NPs) coated with oleic acid and dispersed in a non-polar organic solvent have been synthesized by chemical routes. Different volume fractions, φ, of magnetic NPs were considered. The overall structural characterization of NPs has been performed by x-ray diffractometry, with lattice parameters and average coherence lengths evaluated via Rietveld refinements. The magnetic properties of different samples have been analysed by SQUID magnetometry and temperature-dependent Mössbauer spectroscopy and finally explained by adequate magnetic relaxation mechanisms. Zero field cooling-field cooling protocols provided useful information about specific volume fraction dependent magnetic relaxation and de-freezing processes, the lack of the Verwey transition and stronger dipolar interactions at higher volume fractions. Anisotropy energies as obtained by both temperature dependent Mössbauer spectroscopy and magnetometry data are compared and a new procedure for a quantitative characterization of the dipolar interactions is proposed.

  13. Reconstruction of soot temperature and volume fraction profiles of an asymmetric flame using stereoscopic tomography

    SciTech Connect

    Huang, Qun-xing; Wang, Fei; Liu, Dong; Ma, Zeng-yi; Yan, Jian-hua; Chi, Yong; Cen, Ke-fa

    2009-03-15

    The present study attempts to reconstruct soot temperature and volume fraction distributions for the asymmetric diffusive flame using a tomography technique. A high-resolution camera equipped with a stereo adapter was employed to capture stereoscopic flame images, which were used to obtain monochromatic line-of-sight flame emission projections within the visible range. A matrix-decomposition-based least squares algorithm was introduced to reconstruct the emission intensity distributions in the flame sections. The retrieved intensities were used to infer local soot temperature and volume fraction. Numerical assessments show that for soot volume fraction measurement, the system signal-to-noise ratio should be larger than 62.5 dB. The proposed tomography system was found to be capable of symmetric and asymmetric flame measurements. (author)

  14. A Novel Semiautomated Fractional Limb Volume Tool for Rapid and Reproducible Fetal Soft Tissue Assessment.

    PubMed

    Mack, Lauren M; Kim, Sung Yoon; Lee, Sungmin; Sangi-Haghpeykar, Haleh; Lee, Wesley

    2016-07-01

    The purpose of this study was to document the reproducibility and efficiency of a semiautomated image analysis tool that rapidly provides fetal fractional limb volume measurements. Fifty pregnant women underwent 3-dimensional sonographic examinations for fractional arm and thigh volumes at a mean menstrual age of 31.3 weeks. Manual and semiautomated fractional limb volume measurements were calculated, with the semiautomated measurements calculated by novel software (5D Limb Vol; Samsung Medison, Seoul, Korea). The software applies an image transformation method based on the major axis length, minor axis length, and limb center coordinates. A transformed image is used to perform a global optimization technique for determination of an optimal limb soft tissue boundary. Bland-Altman analysis defined bias with 95% limits of agreement (LOA) between methods, and timing differences between manual versus automated methods were compared by a paired t test. Bland-Altman analysis indicated an acceptable bias with 95% LOA between the manual and semiautomated methods: mean arm volume ± SD, 1.7% ± 4.6% (95% LOA, -7.3% to 10.7%); and mean thigh volume, 0.0% ± 3.8% (95% LOA, -7.5% to 7.5%). The computer-assisted software completed measurements about 5 times faster compared to manual tracings. In conclusion, semiautomated fractional limb volume measurements are significantly faster to calculate when compared to a manual procedure. These results are reproducible and are likely to reduce operator dependency. The addition of computer-assisted fractional limb volume to standard biometry may improve the precision of estimated fetal weight by adding a soft tissue component to the weight estimation process. PMID:27269002

  15. A Novel Semiautomated Fractional Limb Volume Tool for Rapid and Reproducible Fetal Soft Tissue Assessment.

    PubMed

    Mack, Lauren M; Kim, Sung Yoon; Lee, Sungmin; Sangi-Haghpeykar, Haleh; Lee, Wesley

    2016-07-01

    The purpose of this study was to document the reproducibility and efficiency of a semiautomated image analysis tool that rapidly provides fetal fractional limb volume measurements. Fifty pregnant women underwent 3-dimensional sonographic examinations for fractional arm and thigh volumes at a mean menstrual age of 31.3 weeks. Manual and semiautomated fractional limb volume measurements were calculated, with the semiautomated measurements calculated by novel software (5D Limb Vol; Samsung Medison, Seoul, Korea). The software applies an image transformation method based on the major axis length, minor axis length, and limb center coordinates. A transformed image is used to perform a global optimization technique for determination of an optimal limb soft tissue boundary. Bland-Altman analysis defined bias with 95% limits of agreement (LOA) between methods, and timing differences between manual versus automated methods were compared by a paired t test. Bland-Altman analysis indicated an acceptable bias with 95% LOA between the manual and semiautomated methods: mean arm volume ± SD, 1.7% ± 4.6% (95% LOA, -7.3% to 10.7%); and mean thigh volume, 0.0% ± 3.8% (95% LOA, -7.5% to 7.5%). The computer-assisted software completed measurements about 5 times faster compared to manual tracings. In conclusion, semiautomated fractional limb volume measurements are significantly faster to calculate when compared to a manual procedure. These results are reproducible and are likely to reduce operator dependency. The addition of computer-assisted fractional limb volume to standard biometry may improve the precision of estimated fetal weight by adding a soft tissue component to the weight estimation process.

  16. Hippocampal volume and cingulum bundle fractional anisotropy are independently associated with verbal memory in older adults.

    PubMed

    Ezzati, Ali; Katz, Mindy J; Lipton, Michael L; Zimmerman, Molly E; Lipton, Richard B

    2016-09-01

    The objective of this study was to investigate the relationship of medial temporal lobe and posterior cingulate cortex (PCC) volumetrics as well as fractional anisotropy of the cingulum angular bundle (CAB) and the cingulum cingulate gyrus (CCG) bundle to performance on measures of verbal memory in non-demented older adults. The participants were 100 non-demented adults over the age of 70 years from the Einstein Aging Study. Volumetric data were estimated from T1-weighted images. The entire cingulum was reconstructed using diffusion tensor MRI and probabilistic tractography. Association between verbal episodic memory and MRI measures including volume of hippocampus (HIP), entorhinal cortex (ERC), PCC and fractional anisotropy of CAB and CCG bundle were modeled using linear regression. Relationships between atrophy of these structures and regional cingulum fractional anisotropy were also explored. Decreased HIP volume on the left and decreased fractional anisotropy of left CAB were associated with lower memory performance. Volume changes in ERC, PCC and CCG disruption were not associated with memory performance. In regression models, left HIP volume and left CAB-FA were each independently associated with episodic memory. The results suggest that microstructural changes in the left CAB and decreased left HIP volume independently influence episodic memory performance in older adults without dementia. The importance of these findings in age and illness-related memory decline require additional exploration. PMID:26424564

  17. Two-dimensional echocardiographic assessment of left ventricular volumes and ejection fraction in children

    SciTech Connect

    Mercier, J.C.; DiSessa, T.G.; Jarmakani, J.M.; Nakanishi, T.; Hiraishi, S.; Isabel-Jones, J.; Friedman, W.F.

    1982-05-01

    The ability of two-dimensional echocardiography to measure left ventricular volumes and ejection fraction was evaluated in 25 children with congenital heart disease. Dimensions and planimetered areas were obtained in the short-axis view at the mitral valve and high and low papillary muscle levels and in the apical two- and four-chamber views. Eight algorithms using five geometric models were assessed. Left ventricular end-diastolic volume, end-systolic volume and ejection fraction were compared with data from biplane cineangiocardiograms. The correlation varied with the algorithm used. Algorithms using short-axis views appeared superior to those using only apical long-axis views. Four algorithms estimated left ventricular volumes with equal accuracy (Simpson's rule, assuming the ventricle to be a truncated cone; Simpson's rule, algorithm that best estimated left ventricular ejection fraction was the ellipsoid biplane formula using the short-axis view at the papillary muscle level (r = 0.91, slope = 0.94, SEE = 6.7%). Thus, two-dimensional echocardiography can accurately assess left ventricular volumes and ejection fraction in children with congenital heart disease.

  18. Effect of Oil Palm Fibres Volume Fraction on Mechanical Properties of Polyester Composites

    NASA Astrophysics Data System (ADS)

    Yousif, B. F.

    The effect of two types of oil palm fibres (bunch and fruit) on mechanical properties of polyester composites is examined in the current work considering different volume fractions. Tensile, compression, and flexural properties of the composites were investigated. In addition to that, tensile strengths were calculated theoretically using Hirsch model. Scanning electron microscope (SEM) was used to observe the fracture mechanism of the specimens. Single fibre pull-out tests were performed to determine the interfacial shear strength between polyester resin and both types of oil palm fibres. Results revealed that both types of oil palm fibres enhanced the mechanical performance of polyester composites. At a higher volume fraction (40-50%), tensile strength of the polyester composite was improved, i.e., 2.5 times improvement in the tensile strength value. Experimental tensile strength values of oil palm bunch/polyester composites have a good correlation with the theoretical results, especially at low volume fractions of fibre. Flexural strength of polyester worsened with oil palm fibres at all volume fractions of fibre.

  19. Planar measurements of soot volume fraction and OH in a JP-8 pool fire

    SciTech Connect

    Henriksen, Tara L.; Ring, Terry A.; Eddings, Eric G.; Nathan, Graham J.; Alwahabi, Zeyad T.; Qamar, Nader

    2009-07-15

    The simultaneous measurement of soot volume fraction by laser induced incandescence (LII) and qualitative imaging of OH by laser induced fluorescence (LIF) was performed in a JP-8 pool fire contained in a 152 mm diameter pan. Line of sight extinction was used to calibrate the LII system in a laminar flame, and to provide an independent method of measuring average soot volume fraction in the turbulent flame. The presence of soot in the turbulent flame was found to be approximately 50% probable, resulting in high levels of optical extinction, which increased slightly through the flame from approximately 30% near the base, to approximately 50% at the tip. This high soot loading pushes both techniques toward their detection limit. Nevertheless, useful accuracy was obtained, with the LII measurement of apparent extinction in the turbulent flame being approximately 21% lower than a direct measurement, consistent with the influence of signal trapping. The axial and radial distributions of soot volume fraction are presented, along with PDFs of volume fraction, and new insight into the behavior of soot sheets in pool fires are sought from the simultaneous measurements of OH and LII. (author)

  20. Fractionation of Saprolegnia diclina (Oomycetes) satelite DNAs by AgNO3/Cs2SO4 density gradient centrifugation.

    PubMed

    Neish, G A; Green, B R

    1977-12-14

    Saprolegnia diclina DNA has been fractionated using preparative AgNO3/Cs2SO4 and CsCl density gradients. In addition to the previously identified major satellite DNA, there are two minor DNA components banding at 1.682 and 1.701 g - cm(-3) in CsCl. Purified major satellite DNA bands at 1.707 g - cm(-3) giving a base composition of 48% G + C in good agreement with 47% G + C calculated from its Tm value. The nuclear DNA base composition is 58% G + C by both methods. The base composition of the major satellite DNA suggests that it may represent ribosomal DNA cistrons.

  1. Volume Fraction Determination in Cast Superalloys and DS Eutectic Alloys by a New Practice for Manual Point Counting

    NASA Technical Reports Server (NTRS)

    Andrews, C. W.

    1976-01-01

    Volume fraction of a constituent or phase was estimated in six specimens of conventional and DS-eutectic superalloys, using ASTM E562-76, a new standard recommended practice for determining volume fraction by systematic manual point count. Volume fractions determined ranged from 0.086 to 0.36, and with one exception, the 95 percent relative confidence limits were approximately 10 percent of the determined volume fractions. Since the confidence-limit goal of 10 percent, which had been arbitrarily chosen previously, was achieved in all but one case, this application of the new practice was considered successful.

  2. Determination of volume fractions in two-phase flows from sound speed measurement

    SciTech Connect

    Chaudhuri, Anirban; Sinha, Dipen N.; Osterhoudt, Curtis F.

    2012-08-15

    Accurate measurement of the composition of oil-water emulsions within the process environment is a challenging problem in the oil industry. Ultrasonic techniques are promising because they are non-invasive and can penetrate optically opaque mixtures. This paper presents a method of determining the volume fractions of two immiscible fluids in a homogenized two-phase flow by measuring the speed of sound through the composite fluid along with the instantaneous temperature. Two separate algorithms are developed by representing the composite density as (i) a linear combination of the two densities, and (ii) a non-linear fractional formulation. Both methods lead to a quadratic equation with temperature dependent coefficients, the root of which yields the volume fraction. The densities and sound speeds are calibrated at various temperatures for each fluid component, and the fitted polynomial is used in the final algorithm. We present results when the new algorithm is applied to mixtures of crude oil and process water from two different oil fields, and a comparison of our results with a Coriolis meter; the difference between mean values is less than 1%. Analytical and numerical studies of sensitivity of the calculated volume fraction to temperature changes and calibration errors are also presented.

  3. Tumor classification using perfusion volume fractions in breast DCE-MRI

    NASA Astrophysics Data System (ADS)

    Lee, Sang Ho; Kim, Jong Hyo; Park, Jeong Seon; Park, Sang Joon; Jung, Yun Sub; Song, Jung Joo; Moon, Woo Kyung

    2008-03-01

    This study was designed to classify contrast enhancement curves using both three-time-points (3TP) method and clustering approach at full-time points, and to introduce a novel evaluation method using perfusion volume fractions for differentiation of malignant and benign lesions. DCE-MRI was applied to 24 lesions (12 malignant, 12 benign). After region growing segmentation for each lesion, hole-filling and 3D morphological erosion and dilation were performed for extracting final lesion volume. 3TP method and k-means clustering at full-time points were applied for classifying kinetic curves into six classes. Intratumoral volume fraction for each class was calculated. ROC and linear discriminant analyses were performed with distributions of the volume fractions for each class, pairwise and whole classes, respectively. The best performance in each class showed accuracy (ACC), 84.7% (sensitivity (SE), 100%; specificity (SP), 66.7% to a single class) to 3TP method, whereas ACC, 73.6% (SE, 41.7%; SP, 100% to a single class) to k-means clustering. The best performance in pairwise classes showed ACC, 75% (SE, 83.3%; SP, 66.7% to four class pairs and SE, 58.3%; SP, 91.7% to a single class pair) to 3TP method and ACC, 75% (SE, 75%; SP, 75% to a single class pair and SE, 66.7%; SP, 83.3% to three class pairs) to k-means clustering. The performance in whole classes showed ACC, 75% (SE, 83.3%; SP, 66.7%) to 3TP method and ACC, 75% (SE, 91.7%; 58.3%) to k-means clustering. The results indicate that tumor classification using perfusion volume fractions is helpful in selecting meaningful kinetic patterns for differentiation of malignant and benign lesions, and that two different classification methods are complementary to each other.

  4. The equivalent electrical permittivity of gas-solid mixtures at intermediate solid volume fractions.

    SciTech Connect

    Torczynski, John Robert; Ceccio, Steven Louis; Tortora, Paul Richard

    2005-07-01

    Several mixture models are evaluated for their suitability in predicting the equivalent permittivity of dielectric particles in a dielectric medium for intermediate solid volume fractions (0.4 to 0.6). Predictions of the Maxwell, Rayleigh, Bottcher and Bruggeman models are compared to computational simulations of several arrangements of solid particles in a gas and to the experimentally determined permittivity of a static particle bed. The experiment uses spherical glass beads in air, so air and glass permittivity values (1 and 7, respectively) are used with all of the models and simulations. The experimental system used to measure the permittivity of the static particle bed and its calibration are described. The Rayleigh model is found to be suitable for predicting permittivity over the entire range of solid volume fractions (0-0.6).

  5. Damping behavior of polymer composites with high volume fraction of NiMnGa powders

    NASA Astrophysics Data System (ADS)

    Sun, Xiaogang; Song, Jie; Jiang, Hong; Zhang, Xiaoning; Xie, Chaoying

    2011-03-01

    Polymer composites inserted with high volume fraction (up to 70 Vol%) of NiMnGa powders were fabricated and their damping behavior was investigated by dynamic mechanical analysis. It is found that the polymer matrix has little influence on the transformation temperatures of NiMnGa powders. A damping peak appears for NiMnGa/epoxy resin (EP) composites accompanying with the martensitic transformation or reverse martensitic transformation of NiMnGa powders during cooling or heating. The damping capacity for NiMnGa/EP composites increases linearly with the increase of volume fraction of NiMnGa powders and, decreases dramatically as the test frequency increases. The fracture strain of NiMnGa/EP composites decrease with the increase of NiMnGa powders.

  6. Influence of Martensite Volume Fraction on Impact Properties of Triple Phase (TP) Steels

    NASA Astrophysics Data System (ADS)

    Zare, Ahmad; Ekrami, A.

    2013-03-01

    Ferrite-bainite-martensite triple phase (TP) microstructures with different volume fractions of martensite were obtained by changing heat treatment time during austempering at 300 °C. Room temperature impact properties of TP steels with different martensite volume fractions ( V M) were determined by means of Charpy impact testing. The effects of test temperature on impact properties were also investigated for two selected microstructures containing 0 (the DP steel) and 8.5 vol.% martensite. Test results showed reduction in toughness with increasing V M in TP steels. Fracture toughness values for the DP and TP steels with 8.5 vol.% martensite were obtained from correlation between fracture toughness and the Charpy impact energy. Fractography of Charpy specimens confirmed decrease in TP steels' toughness with increasing V M by considering and comparing radial marks and crack initiation regions at the fracture surfaces of the studied steels.

  7. Sparger Effects on Gas Volume Fraction Distributions in Vertical Bubble-Column Flows as Measured by Gamma-Densitometry Tomography

    SciTech Connect

    GEORGE,DARIN L.; SHOLLENBERGER,KIM ANN; TORCZYNSKI,JOHN R.

    2000-01-18

    Gamma-densitometry tomography is applied to study the effect of sparger hole geometry, gas flow rate, column pressure, and phase properties on gas volume fraction profiles in bubble columns. Tests are conducted in a column 0.48 m in diameter, using air and mineral oil, superficial gas velocities ranging from 5 to 30 cm s{sup -1}, and absolute column pressures from 103 to 517 kPa. Reconstructed gas volume fraction profiles from two sparger geometries are presented. The development length of the gas volume fraction profile is found to increase with gas flow rate and column pressure. Increases in gas flow rate increase the local gas volume fraction preferentially on the column axis, whereas increases in column pressure produce a uniform rise in gas volume fraction across the column. A comparison of results from the two spargers indicates a significant change in development length with the number and size of sparger holes.

  8. Effect of Martensite Volume Fraction on Forming Limit Diagrams of Dual-Phase Steel

    NASA Astrophysics Data System (ADS)

    Zaeimi, Mohammad; Basti, Ali; Alitavoli, Majid

    2015-05-01

    Prediction of the onset of failure due to localized necking has an important role on the determination of the formability of sheet metal, especially dual-phase steels, because of their increasing applications in the automotive industry. In the present study, a new application of the M-K model and theoretical forming limit diagram has been proposed. It is shown that this model can be useful in predicting the effect of microstructural aspects on the formability of dual-phase steels. For this purpose, the limiting strains of the dual-phase (ferrite-martensite) steel under different martensite volume fractions have been calculated. Furthermore, the effect of the heating rate on the formability of the DP samples has been predicted. To solve the non-linear system of equations, the modified Newton-Raphson method has been used. The results show that the limiting strains decrease by increasing the amount of martensite volume fractions. Furthermore, by increasing the heating rate, the dependence of the forming limit curves on the martensite volume fraction will be decreased.

  9. A framework to measure myocardial extracellular volume fraction using dual-phase low dose CT images

    SciTech Connect

    Liu, Yixun; Summers, Ronald M.; Yao, Jianhua; Liu, Songtao; Sibley, Christopher T.; Bluemke, David A.; Nacif, Marcelo S.

    2013-10-15

    Purpose: Myocardial extracellular volume fraction (ECVF) is a surrogate imaging biomarker of diffuse myocardial fibrosis, a hallmark of pathologic ventricular remodeling. Low dose cardiac CT is emerging as a promising modality to detect diffuse interstitial myocardial fibrosis due to its fast acquisition and low radiation; however, the insufficient contrast in the low dose CT images poses great challenge to measure ECVF from the image. Methods: To deal with this difficulty, the authors present a complete ECVF measurement framework including a point-guided myocardial modeling, a deformable model-based myocardium segmentation, nonrigid registration of pre- and post-CT, and ECVF calculation. Results: The proposed method was evaluated on 20 patients by two observers. Compared to the manually delineated reference segmentations, the accuracy of our segmentation in terms of true positive volume fraction (TPVF), false positive volume fraction (FPVF), and average surface distance (ASD), were 92.18% ± 3.52%, 0.31% ± 0.10%, 0.69 ± 0.14 mm, respectively. The interobserver variability measured by concordance correlation coefficient regarding TPVF, FPVF, and ASD were 0.95, 0.90, 0.94, respectively, demonstrating excellent agreement. Bland-Altman method showed 95% limits of agreement between ECVF at CT and ECVF at MR. Conclusions: The proposed framework demonstrates its efficiency, accuracy, and noninvasiveness in ECVF measurement and dramatically advances the ECVF at cardiac CT toward its clinical use.

  10. Soot volume fraction in a piloted turbulent jet non-premixed flame of natural gas

    SciTech Connect

    Qamar, N.H.; Alwahabi, Z.T.; King, K.D.; Chan, Q.N.; Nathan, G.J.; Roekaerts, D.

    2009-07-15

    Planar laser-induced incandescence (LII) has been used to measure soot volume fraction in a well-characterised, piloted, turbulent non-premixed flame known as the ''Delft Flame III''. Simulated Dutch natural gas was used as the fuel to produce a flame closely matching those in which a wide range of previous investigations, both experimental and modelling, have been performed. The LII method was calibrated using a Santoro-style burner with ethylene as the fuel. Instantaneous and time-averaged data of the axial and radial soot volume fraction distributions of the flame are presented here along with the Probability Density Functions (PDFs) and intermittency. The PDFs were found to be well-characterised by a single exponential distribution function. The distribution of soot was found to be highly intermittent, with intermittency typically exceeding 97%, which increases measurement uncertainty. The instantaneous values of volume fraction are everywhere less than the values in strained laminar flames. This is consistent with the soot being found locally in strained flame sheets that are convected and distorted by the flow. (author)

  11. Fiber Volume Fraction Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

    NASA Astrophysics Data System (ADS)

    Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

    2016-06-01

    Liquid resin is injected into the tapered injection chamber through the injection slots to completely wetout the fiber reinforcements in a resin injection pultrusion process. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the centerline causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to effectively penetrate through the fibers and achieve complete wetout. Fiber volume fraction in the final pultruded composite is a key to decide the mechanical and/or chemical properties of the composite. If the fiber volume fraction is too high, more fibers are squeezed together creating a fiber lean region near the wall and fiber rich region away from the wall. Also, the design of the injection chamber significantly affects the minimum injection pressure required to completely wet the fibers. A tapered injection chamber is considered such that wetout occurs at lower injection pressures due to the taper angle of the injection chamber. In this study, the effect of fiber volume fraction on the fiber reinforcement compaction and complete fiber wetout for a tapered injection chamber is investigated.

  12. [Volume fraction of gas vesicle and floating characteristics of cyanobacteria in Taihu Lake under different pressures].

    PubMed

    Wang, Wei; Cong, Hai-Bing; Xu, Ya-Jun; Chen, Wen-Jing; Xu, Si-Tao; Wu, Jun; Jiang, Xin-Yue

    2014-08-01

    In order to ascertain the volumetric change of gas vesicles in cyanobacteria and the floating characteristics, capillary pressure method and image analysis method were used to study burst situation and remanent volume fraction of gas vesicles in cyanobacteria under different pressures. The reform situation after pressuring was also analyzed in this research. The results showed that the volume fraction of gas vesicles in Taihu Lake were 29.52%, 5.73%, 4.43%, 2.71%, 2.46%, 2.19% under 0 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa determined by the image analysis, and were 10.93%, 1.14%, 0.90%, 0.27%, 0.14%, 0.04% determined by the capillary pressure method; cyanobacteria sank due to the gas vesicles' bursting when the pressure was greater than 0.4 MPa. Gas vesicles and structure after pressure were reformed with the lapse of time, under 1 000 lx, 25 degrees C, after 8 h, 24 h, 48 h, the reformed gas vesicles accounted for 31.02%, 45.68%, 81.05% of total gas vesicles before pressuring. Image analysis method is more accurate in the determination for cyanobacteria gas vesicles' volume, while the volume is smaller measured by traditional capillary pressure method.

  13. White matter microstructure asymmetry: effects of volume asymmetry on fractional anisotropy asymmetry.

    PubMed

    Takao, H; Hayashi, N; Ohtomo, K

    2013-02-12

    Diffusion tensor imaging (DTI) provides information regarding white matter microstructure; however, macroscopic fiber architectures can affect DTI measures. A larger brain (fiber tract) has a 'relatively' smaller voxel size, and the voxels are less likely to contain more than one fiber orientation and more likely to have higher fractional anisotropy (FA). Previous DTI studies report left-to-right differences in the white matter; however, these may reflect true microscopic differences or be caused purely by volume differences. Using tract-based spatial statistics, we investigated left-to-right differences in white matter microstructure across the whole brain. Voxel-wise analysis revealed a large number of white matter volume asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. In many white matter regions, FA asymmetry was positively correlated with volume asymmetry. Voxel-wise analysis with adjustment for volume asymmetry revealed many white matter FA asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. The voxel-wise analysis showed a reduced number of regions with significant FA asymmetry compared with analysis performed without adjustment for volume asymmetry; however, the overall trend of the results was unchanged. The results of the present study suggest that these FA asymmetries are not caused by volume differences and reflect microscopic differences in the white matter.

  14. Physical aging and structural recovery in a colloidal glass subjected to volume-fraction jump conditions.

    PubMed

    Peng, Xiaoguang; McKenna, Gregory B

    2016-04-01

    Three important kinetic phenomena have been cataloged by Kovacs in the investigation of molecular glasses during structural recovery or physical aging. These are responses to temperature-jump histories referred to as intrinsic isotherms, asymmetry of approach, and memory effect. Here we use a thermosensitive polystyrene-poly (N-isopropylacrylamide)-poly (acrylic acid) core-shell particle-based dispersion as a colloidal model and by working at a constant number concentration of particles we use temperature changes to create volume-fraction changes. This imposes conditions similar to those defined by Kovacs on the colloidal system. We use creep experiments to probe the physical aging and structural recovery behavior of colloidal glasses in the Kovacs-type histories and compare the results with those seen in molecular glasses. We find that there are similarities in aging dynamics between molecular glasses and colloidal glasses, but differences also persist. For the intrinsic isotherms, the times t_{eq} needed for relaxing or evolving into the equilibrium (or stationary) state are relatively insensitive to the volume fraction and the values of t_{eq} are longer than the α-relaxation time τ_{α} at the same volume fraction. On the other hand, both of these times grow at least exponentially with decreasing temperature in molecular glasses. For the asymmetry of approach, similar nonlinear behavior is observed for both colloidal and molecular glasses. However, the equilibration time t_{eq} is the same for both volume-fraction up-jump and down-jump experiments, different from the finding in molecular glasses that it takes longer for the structure to evolve into equilibrium for the temperature up-jump condition than for the temperature down-jump condition. For the two-step volume-fraction jumps, a memory response is observed that is different from observations of structural recovery in two-step temperature histories in molecular glasses. The concentration dependence of the

  15. Physical aging and structural recovery in a colloidal glass subjected to volume-fraction jump conditions

    NASA Astrophysics Data System (ADS)

    Peng, Xiaoguang; McKenna, Gregory B.

    2016-04-01

    Three important kinetic phenomena have been cataloged by Kovacs in the investigation of molecular glasses during structural recovery or physical aging. These are responses to temperature-jump histories referred to as intrinsic isotherms, asymmetry of approach, and memory effect. Here we use a thermosensitive polystyrene-poly (N -isopropylacrylamide)-poly (acrylic acid) core-shell particle-based dispersion as a colloidal model and by working at a constant number concentration of particles we use temperature changes to create volume-fraction changes. This imposes conditions similar to those defined by Kovacs on the colloidal system. We use creep experiments to probe the physical aging and structural recovery behavior of colloidal glasses in the Kovacs-type histories and compare the results with those seen in molecular glasses. We find that there are similarities in aging dynamics between molecular glasses and colloidal glasses, but differences also persist. For the intrinsic isotherms, the times teq needed for relaxing or evolving into the equilibrium (or stationary) state are relatively insensitive to the volume fraction and the values of teq are longer than the α -relaxation time τα at the same volume fraction. On the other hand, both of these times grow at least exponentially with decreasing temperature in molecular glasses. For the asymmetry of approach, similar nonlinear behavior is observed for both colloidal and molecular glasses. However, the equilibration time teq is the same for both volume-fraction up-jump and down-jump experiments, different from the finding in molecular glasses that it takes longer for the structure to evolve into equilibrium for the temperature up-jump condition than for the temperature down-jump condition. For the two-step volume-fraction jumps, a memory response is observed that is different from observations of structural recovery in two-step temperature histories in molecular glasses. The concentration dependence of the dynamics

  16. A novel optical method for estimating the near-wall volume fraction in granular flows

    NASA Astrophysics Data System (ADS)

    Sarno, Luca; Nicolina Papa, Maria; Carleo, Luigi; Tai, Yih-Chin

    2016-04-01

    Geophysical phenomena, such as debris flows, pyroclastic flows and rock avalanches, involve the rapid flow of granular mixtures. Today the dynamics of these flows is far from being deeply understood, due to their huge complexity compared to clear water or monophasic fluids. To this regard, physical models at laboratory scale represent important tools for understanding the still unclear properties of granular flows and their constitutive laws, under simplified experimental conditions. Beside the velocity and the shear rate, the volume fraction is also strongly interlinked with the rheology of granular materials. Yet, a reliable estimation of this quantity is not easy through non-invasive techniques. In this work a novel cost-effective optical method for estimating the near-wall volume fraction is presented and, then, applied to a laboratory study on steady-state granular flows. A preliminary numerical investigation, through Monte-Carlo generations of grain distributions under controlled illumination conditions, allowed to find the stochastic relationship between the near-wall volume fraction, c3D, and a measurable quantity (the two-dimensional volume fraction), c2D, obtainable through an appropriate binarization of gray-scale images captured by a camera placed in front of the transparent boundary. Such a relation can be well described by c3D = aexp(bc2D), with parameters only depending on the angle of incidence of light, ζ. An experimental validation of the proposed approach is carried out on dispersions of white plastic grains, immersed in various ambient fluids. The mixture, confined in a box with a transparent window, is illuminated by a flickering-free LED lamp, placed so as to form a given ζ with the measuring surface, and is photographed by a camera, placed in front of the same window. The predicted exponential law is found to be in sound agreement with experiments for a wide range of ζ (10° <ζ<45°). The technique is, then, applied to steady-state dry

  17. Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead.

    PubMed

    Yang, Sha; Liu, Yun

    2015-01-01

    The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wave function. Equilibrium (202)Hg/(198)Hg, (205)Tl/(203)Tl, (207)Pb/(206)Pb and (208)Pb/(206)Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of [formula in text] for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb(4+)-bearing species are found can enrich heavier Pb isotopes than Pb(2+)-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of (208)Pb/(206)Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb(2+)-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., [formula in text]) and odd-mass MIFs (i.e., [formula in text) are almost the same but with opposite signs. PMID:26224248

  18. Mapping mean axon diameter and axonal volume fraction by MRI using temporal diffusion spectroscopy

    PubMed Central

    Xu, Junzhong; Li, Hua; Harkins, Kevin D.; Jiang, Xiaoyu; Xie, Jingping; Kang, Hakmook; Does, Mark D.; Gore, John C.

    2014-01-01

    Mapping mean axon diameter and intra-axonal volume fraction may have significant clinical potential because nerve conduction velocity is directly dependent on axon diameter, and several neurodegenerative diseases affect axons of specific sizes and alter axon counts. Diffusion-weighted MRI methods based on the pulsed gradient spin echo (PGSE) sequence have been reported to be able to assess axon diameter and volume fraction non-invasively. However, due to the relatively long diffusion times used, e.g. > 20 ms, the sensitivity to small axons (diameter < 2 µm) is low, and the derived mean axon diameter has been reported to be overestimated. In the current study, oscillating gradient spin echo (OGSE) diffusion sequences with variable frequency gradients were used to assess rat spinal white matter tracts with relatively short effective diffusion times (1 – 5 ms). In contrast to previous PGSE-based methods, the extra-axonal diffusion cannot be modeled as hindered (Gaussian) diffusion when short diffusion times are used. Appropriate frequency-dependent rates are therefore incorporated into our analysis and validated by histology-based computer simulation of water diffusion. OGSE data were analyzed to derive mean axon diameters and intra-axonal volume fractions of rat spinal white matter tracts (mean axon diameter ~ 1.27 – 5.54 µm). The estimated values were in good agreement with histology, including the small axon diameters (< 2.5 µm). This study establishes a framework for quantification of nerve morphology using the OGSE method with high sensitivity to small axons. PMID:25225002

  19. Variation of bone layer thicknesses and trabecular volume fraction in the adult male human calvarium.

    PubMed

    Boruah, Sourabh; Paskoff, Glenn R; Shender, Barry S; Subit, Damien L; Salzar, Robert S; Crandall, Jeff R

    2015-08-01

    The human calvarium is a sandwich structure with two dense layers of cortical bone separated by porous cancellous bone. The variation of the three dimensional geometry, including the layer thicknesses and the volume fraction of the cancellous layer across the population, is unavailable in the current literature. This information is of particular importance to mathematical models of the human head used to simulate mechanical response. Although the target geometry for these models is the median geometry of the population, the best attempt so far has been the scaling of a unique geometry based on a few median anthropometric measurements of the head. However, this method does not represent the median geometry. This paper reports the average three dimensional geometry of the calvarium from X-ray computed tomography (CT) imaging and layer thickness and trabecular volume fraction from micro CT (μCT) imaging of ten adult male post-mortem human surrogates (PMHS). Skull bone samples have been obtained and μCT imaging was done at a resolution of 30 μm. Monte Carlo simulation was done to estimate the variance in these measurements due to the uncertainty in image segmentation. The layer thickness data has been averaged over areas of 5mm(2). The outer cortical layer was found to be significantly (p < 0.01; Student's t test) thicker than the inner layer (median of thickness ratio 1.68). Although there was significant location to location difference in all the layer thicknesses and volume fraction measurements, there was no trend. Average distribution and the variance of these metrics on the calvarium have been shown. The findings have been reported as colormaps on a 2D projection of the cranial vault. PMID:25920690

  20. Study of the free volume fraction in polylactic acid (PLA) by thermal analysis

    NASA Astrophysics Data System (ADS)

    Abdallah, A.; Benrekaa, N.

    2015-10-01

    The poly (lactic acid) or polylactide (PLA) is a biodegradable polymer with high modulus, strength and thermoplastic properties. In this work, the evolution of various properties of PLA is studied, such as glass transition temperature, mechanical modules and elongation percentage with the aim of investigating the free volume fraction. To do so, two thermal techniques have been used: the dynamic mechanical analysis (DMA) and dilatometry. The results obtained by these techniques are combined to go back to the structural properties of the studied material.

  1. Cup-Drawing Behavior of High-Strength Steel Sheets Containing Different Volume Fractions of Martensite

    NASA Astrophysics Data System (ADS)

    Choi, Shi-Hoon; Kim, Dae-Wan; Yang, Hoe-Seok; Han, Seong-Ho; Yoon, Jeong Whan

    2010-06-01

    Planar anisotropy and cup-drawing behavior were investigated for high-strength steel sheets containing different volume fractions of martensite. Macrotexture analysis using XRD was conducted to capture the effect of crystallographic orientation on the planar anisotropy of high-strength steel sheets. A phenomenological yield function, Yld96, which accounts for the anisotropy of yield stress and r-values, was implemented into ABAQUS using the user subroutine UMAT. Cup drawing of high-strength steel sheets was simulated using the FEM code. The profiles of earing and thickness strain were compared with the experimentally measured results.

  2. Solid volume fraction estimation of bone:marrow replica models using ultrasound transit time spectroscopy.

    PubMed

    Wille, Marie-Luise; Langton, Christian M

    2016-02-01

    The acceptance of broadband ultrasound attenuation (BUA) for the assessment of osteoporosis suffers from a limited understanding of both ultrasound wave propagation through cancellous bone and its exact dependence upon the material and structural properties. It has recently been proposed that ultrasound wave propagation in cancellous bone may be described by a concept of parallel sonic rays; the transit time of each ray defined by the proportion of bone and marrow propagated. A Transit Time Spectrum (TTS) describes the proportion of sonic rays having a particular transit time, effectively describing the lateral inhomogeneity of transit times over the surface aperture of the receive ultrasound transducer. The aim of this study was to test the hypothesis that the solid volume fraction (SVF) of simplified bone:marrow replica models may be reliably estimated from the corresponding ultrasound transit time spectrum. Transit time spectra were derived via digital deconvolution of the experimentally measured input and output ultrasonic signals, and compared to predicted TTS based on the parallel sonic ray concept, demonstrating agreement in both position and amplitude of spectral peaks. Solid volume fraction was calculated from the TTS; agreement between true (geometric calculation) with predicted (computer simulation) and experimentally-derived values were R(2)=99.9% and R(2)=97.3% respectively. It is therefore envisaged that ultrasound transit time spectroscopy (UTTS) offers the potential to reliably estimate bone mineral density and hence the established T-score parameter for clinical osteoporosis assessment.

  3. Solid volume fraction estimation of bone:marrow replica models using ultrasound transit time spectroscopy.

    PubMed

    Wille, Marie-Luise; Langton, Christian M

    2016-02-01

    The acceptance of broadband ultrasound attenuation (BUA) for the assessment of osteoporosis suffers from a limited understanding of both ultrasound wave propagation through cancellous bone and its exact dependence upon the material and structural properties. It has recently been proposed that ultrasound wave propagation in cancellous bone may be described by a concept of parallel sonic rays; the transit time of each ray defined by the proportion of bone and marrow propagated. A Transit Time Spectrum (TTS) describes the proportion of sonic rays having a particular transit time, effectively describing the lateral inhomogeneity of transit times over the surface aperture of the receive ultrasound transducer. The aim of this study was to test the hypothesis that the solid volume fraction (SVF) of simplified bone:marrow replica models may be reliably estimated from the corresponding ultrasound transit time spectrum. Transit time spectra were derived via digital deconvolution of the experimentally measured input and output ultrasonic signals, and compared to predicted TTS based on the parallel sonic ray concept, demonstrating agreement in both position and amplitude of spectral peaks. Solid volume fraction was calculated from the TTS; agreement between true (geometric calculation) with predicted (computer simulation) and experimentally-derived values were R(2)=99.9% and R(2)=97.3% respectively. It is therefore envisaged that ultrasound transit time spectroscopy (UTTS) offers the potential to reliably estimate bone mineral density and hence the established T-score parameter for clinical osteoporosis assessment. PMID:26455950

  4. Effects of Mass and Volume Fraction Skewness in Variable Density Mixing Processes

    NASA Astrophysics Data System (ADS)

    Wachtor, Adam J.; Bakosi, Jozsef; Ristorcelli, Raymond

    2015-11-01

    Among the parameters characterizing mixing by variable density turbulence of fluids involving density variations of a factor of 5 to 10 are the Atwood, Froude, Schmidt, and Reynolds numbers. There is evidence that the amount of each fluid present when the two pure fluids mix, as described by the probability density function of the mass or molar (volume) fraction, also strongly affects the mixing process. To investigate this phenomena, implicit large-eddy simulations (ILES) are performed for binary fluid mixtures in statistically homogenous environments under constant acceleration. These coarse grained simulations are used as data for theory validation and mix model development. ILES has been demonstrated to accurately capture the mixing behavior of a passive scalar field through stirring and advection by a turbulent velocity field. The present work advances that research and studies the extent to which an under-resolved active scalar drives the subsequent fluid motion and determines the nature of the mixing process. Effects of initial distributions of the mass and molar (volume) fraction probability density function on the resulting variable density turbulence and mixing are investigated and compared to direct numerical simulations from the Johns Hopkins Turbulence Database. Funded by the LANL LDRD-ER on ``Inserting Nonlinear N-Material Coupling PDF Information into Turbulent Mixing Models'' through exploratory research project number 20150498ER.

  5. Theoretical investigations of uranium isotope fractionation caused by nuclear volume effects

    NASA Astrophysics Data System (ADS)

    Yang, S.

    2015-12-01

    Because the half-life times of uranium isotopes are all very long, e.g., 4.5Ga for 238U and 0.7Ga for 235U, people actually treat uranium isotope system as a stable one in many young geologic systems (e.g., Bopp et al., 2010; Basu et al., 2014). There is an increasing trend of using U isotope method to study surface geochemistry problems. For example, people start to use U isotopes as a new tracer to determine the change of redox conditions (Holmden et al., 2015; Wang et al., 2015). However, there are only a few equilibrium U isotope fractionation factors available right now. The new enterprise of U isotope method requires a much expanded data-base of equilibrium U isotope fractionation factor. Many evidences showed that heavy isotope systems could be significantly fractionated as the consequence of the nuclear volume effect (NVE) or so-called nuclear field shift effect,which is a driving force of mass-independent fractionation induced by differences in nuclear size and nuclear shape of isotopes. Here we theoretically estimate the magnitude of equilibrium isotope fractionation factors of U-bearing gaseous and solid compounds caused by NVE via density functional theory (DFT) quantum chemistry methods with careful evaluation on quantum relativistic effects. Our calculation results show the NVE drives 238U/235U fractionations can be up to -4.43‰ between U(VI) and U(IV) species, or can be up to -1.68‰ between U(IV) and U(III) species, at room temperature. The U4+-bearing species or phases tend to enrich heavier isotopes (i.e., 238U) relative to the oxidized phases (U6+-bearing), and enrich lighter isotopes (i.e., 235U) relative to the reduced U(III) phases (U3+-bearing), which generally agree with the recent experimental results (Wang et al., 2015). Our results provide a base for broad applications of equilibrium U isotope fractionation in surface environments.

  6. Fractionated Mercury Isotopes in Fish: The Effects of Nuclear Mass, Spin, and Volume

    NASA Astrophysics Data System (ADS)

    Das, R.; Odom, A. L.

    2007-12-01

    .3, and thus more than one mass-independent isotope effect is inferred. MIF of mercury can be caused by the nuclear volume effect. Schauble, 2007 has calculated nuclear volume fractionation scaling factors for a number of common mercury chemical species in equilibrium with Hg° vapor. From his calculations the nuclear field shift effect is larger in Δ199Hg than in Δ201Hg by approximately a factor of two. The predominant mercury chemical species in fish is methylmercury cysteine. From the experimental studies of Buchachenko and others (2004) on the reaction of methylmercury chloride with creatine kinase it seems reasonable to predicted that the thiol functional groups of cysteine gets enriched in 199Hg and 201Hg. Here the magnetic isotope effect (MIE) produces a kinetic partial separation of isotopes with non-zero nuclear spin quantum numbers from the even-N isotopes. The ratio of enrichment of Δ201Hg /Δ199Hg is predicted from theory to be 1.11, which is the ratio of the magnetic moments of 199Hg and 201Hg. Because mercury possesses two odd-N isotopes, it is possible to detect and evaluate the effects of two distinct, mass-independent isotope fractionating processes. From the data obtained on fish samples, we can deconvolute the contributions of the isotope effects of nuclear mass, spin and volume. For these samples the role of spin or the magnetic isotope effect is the most dominant.

  7. Validation of quantitative estimation of tissue oxygen extraction fraction and deoxygenated blood volume fraction in phantom and in vivo experiments by using MRI.

    PubMed

    Sedlacik, Jan; Reichenbach, Jürgen R

    2010-04-01

    The blood oxygenation level dependent signal of cerebral tissue can be theoretically derived using a network model formed by randomly oriented infinitely long cylinders. The validation of this model by phantom and in vivo experiments is still an object of research. A network phantom was constructed of solid polypropylene strings immersed in silicone oil, which essentially eliminated the effect of spin diffusion. The volume fraction and magnetic property of the string network was predetermined by independent methods. Ten healthy volunteers were measured for in vivo demonstration. The gradient echo sampled spin echo signal was evaluated with the cylinder network model. We found a strong interdependency between the two network characterizing parameters deoxygenated blood volume and oxygen extraction fraction. Here, different sets of deoxygenated blood volume/oxygen extraction fraction values were able to describe the measured signal equally well. However, by setting one parameter constant to a predetermined value, reasonable estimates of the other parameter were obtained. The same behavior was found for the in vivo demonstration. The signal theory of the cylinder network was validated by a well-characterized phantom. However, the found interdependency that was found between deoxygenated blood volume and oxygen extraction fraction requires an independent estimation of one variable to determine reliable values of the other parameter. PMID:20373392

  8. Applying Linear and Non-Linear Methods for Parallel Prediction of Volume of Distribution and Fraction of Unbound Drug

    PubMed Central

    del Amo, Eva M.; Ghemtio, Leo; Xhaard, Henri; Yliperttula, Marjo; Urtti, Arto; Kidron, Heidi

    2013-01-01

    Volume of distribution and fraction unbound are two key parameters in pharmacokinetics. The fraction unbound describes the portion of free drug in plasma that may extravasate, while volume of distribution describes the tissue access and binding of a drug. Reliable in silico predictions of these pharmacokinetic parameters would benefit the early stages of drug discovery, as experimental measuring is not feasible for screening purposes. We have applied linear and nonlinear multivariate approaches to predict these parameters: linear partial least square regression and non-linear recursive partitioning classification. The volume of distribution and fraction of unbound drug in plasma are predicted in parallel within the model, since the two are expected to be affected by similar physicochemical drug properties. Predictive models for both parameters were built and the performance of the linear models compared to models included in the commercial software Volsurf+. Our models performed better in predicting the unbound fraction (Q2 0.54 for test set compared to 0.38 with Volsurf+ model), but prediction accuracy of the volume of distribution was comparable to the Volsurf+ model (Q2 of 0.70 for test set compared to 0.71 with Volsurf+ model). The nonlinear classification models were able to identify compounds with a high or low volume of distribution (sensitivity 0.81 and 0.71, respectively, for test set), while classification of fraction unbound was less successful. The interrelationship between the volume of distribution and fraction unbound is investigated and described in terms of physicochemical descriptors. Lipophilicity and solubility descriptors were found to have a high influence on both volume of distribution and fraction unbound, but with an inverse relationship. PMID:24116008

  9. High-Pressure Torsion of Ti: Synchrotron characterization of phase volume fraction and domain sizes

    NASA Astrophysics Data System (ADS)

    Bolmaro, Raúl E.; Sordi, Vitor L.; Ferrante, Maurizio; Brokmeier, Heinz-Günter; Kawasaki, Megumi; Langdon, Terence G.

    2014-08-01

    Rods of grade 2 Ti were processed by Equal-Channel Angular Pressing (ECAP) (phi = 120° at 573 K) employing 2, 4 and 6 passes. The same billets were further deformed by High- Pressure Torsion (HPT) at room temperature, varying both the hydrostatic pressure (1 and 6 GPa) and the number of rotations (n = 1 and 5). The ECAP and HPT samples were studied by synchrotron radiation at DESY-Petra III GEMS line. On the ECAP samples, textures were thus determined while for both ECAP and HPT samples the measurements were further analyzed by MAUD. Domain sizes and phase volume fractions were determined as a function of the radial direction of the samples. Alpha and Omega phases were detected in different amounts depending mostly on hydrostatic pressure and shear deformation. These transition phases can be pressure-induced during HPT processing and the results of Vickers microhardness measurements were related to the processing parameters and to the amounts of these phases.

  10. In situ synthesis of calcium phosphate-polycaprolactone nanocomposites with high ceramic volume fractions.

    PubMed

    Makarov, C; Gotman, I; Jiang, X; Fuchs, S; Kirkpatrick, C J; Gutmanas, E Y

    2010-06-01

    Biodegradable calcium phosphate-PCL nanocomposite powders with unusually high ceramic volume fractions (80-95%) and uniform PCL distribution were synthesized by a non-aqueous chemical reaction in the presence of the dissolved polymer. No visible polymer separation occurred during processing. Depending on the reagents combination, either dicalcium phosphate (DCP) or Ca-deficient HA (CDHA) was obtained. CDHA-PCL composite powders were high pressure consolidated at room temperature yielding dense materials with high compressive strengths. Such densification route provides the possibility of incorporating drug and proteins without damaging their biological activity. The CDHA-PCL composites were tested in osteoblastic and endothelial cell line cultures and were found to support the attachment and proliferation of both cell types.

  11. Effect of cooling rate on leucite volume fraction in dental porcelains.

    PubMed

    Mackert, J R; Evans, A L

    1991-02-01

    Prasad et al. (1988) have shown that slow cooling of dental porcelain produces increases in thermal expansion sufficient to make a compatible metal-porcelain system incompatible. The present study was undertaken to determine whether the increase in porcelain thermal expansion might be attributable to crystallization of additional leucite during slow cooling of the porcelain. Eight x-ray diffraction specimens for each of six commercial dental porcelains and for the Component No. 1 frit of the Weinstein and Weinstein (1962) and Weinstein et al. (1962) patents were fabricated and divided into two groups. Specimens in the first group (termed fast-cooled) were cooled in the conventional manner by removing them from the furnace at the maximum firing temperature immediately into room air. Specimens in the second group (termed slow-cooled) were cooled slowly by interrupting power to the furnace muffle and allowing them to cool inside the closed furnace. Quantitative x-ray diffraction was performed on the fast- and slow-cooled porcelain specimens with standards containing leucite volume fractions of 0.111, 0.223, 0.334, and 0.445. Unpaired, one-tailed t tests were performed on the fast- and slow-cool data, and a significant increase (p less than 0.05) in the amount of leucite (as a function of the slow cooling) was found for each of the porcelains. The increases in the leucite volume fractions resulting from the slow cooling ranged from a low of 8.5% to a high of 55.8%, with an average increase of 26.9%.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1991871

  12. A transient method for measuring the gas volume fraction in a mixed gas-liquid flow using acoustic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Dehua; Wang, Xiuming; Che, Chengxuan; Cong, Jiansheng; Xu, Delong; Wang, Xiaomin

    2010-08-01

    In this paper, the feasibility of measuring the gas volume fraction in a mixed gas-liquid flow by using an acoustic resonant spectroscopy (ARS) method in a transient way is studied theoretically and experimentally. Firstly, the effects of sizes and locations of a single air bubble in a cylindrical cavity with two open ends on resonant frequencies are investigated numerically. Then, a transient measurement system for ARS is established, and the trends of the resonant frequencies (RFs) and resonant amplitudes (RAs) in the cylindrical cavity with gas flux inside are investigated experimentally. The measurement results by the proposed transient method are compared with those by steady-state ones and numerical ones. The numerical results show that the RFs of the cavity are highly sensitive to the volume of the single air bubble. A tiny bubble volume perturbation may cause a prominent RF shift even though the volume of the air bubble is smaller than 0.1% of that of the cavity. When the small air bubble moves, the RF shift will change and reach its maximum value as it is located at the middle of the cavity. As the gas volume fraction of the two-phase flow is low, both the RFs and RAs from the measurement results decrease dramatically with the increasing gas volume, and this decreasing trend gradually becomes even as the gas volume fraction increases further. These experimental results agree with the theoretical ones qualitatively. In addition, the transient method for ARS is more suitable for measuring the gas volume fraction with randomness and instantaneity than the steady-state one, because the latter could not reflect the random and instant characteristics of the mixed fluid due to the time consumption for frequency sweeping. This study will play a very important role in the quantitative measurement of the gas volume fraction of multiphase flows.

  13. Applicability of ultrasonic testing for the determination of volume fraction of particulates in alumina-reinforced aluminum matrix composites

    SciTech Connect

    Fang, C.K.; Fang, R.L.; Weng, W.P.; Chuang, T.H.

    1999-10-01

    An ultrasonic testing technique was employed to determine the volume fraction of alumina particulate reinforcement in 6061 aluminum matrix composites. this study was performed on various composites with Al{sub 2}O{sub 3} nominal volume fractions of 10, 15, and 20%. For comparison, other techniques were employed as well, including the Archimedes method, metallographic image analysis, X-ray diffraction, and acid dissolution. Observations indicated that ultrasonic testing and acid dissolution methods are more reliable than the other techniques, while ultrasonic testing is faster than the acid dissolution method.

  14. Rheological modelling of complex fluids. I. The concept of effective volume fraction revisited

    NASA Astrophysics Data System (ADS)

    Quemada, D.

    1998-01-01

    Number of complex fluids (as slurries, drilling muds, paints and coatings, many foods, cosmetics, biofluids...) can approximately be described as concentrated dispersions of Structural Units (SUs). Due to shear forces, SUs are assumed to be approximately spherical in shape and uniform in size under steady flow conditions, so that a complex fluid can be considered as a roughly monodisperse dispersion of roughly spherical SUs (with a shear-dependent mean radius), what allows to generalize hard sphere models of monodisperse suspensions to complex fluids. A rheological model of such dispersions of SUs is based on the concept of the effective volume fraction, φ_{eff} which depends on flow conditions. Indeed, in competition with particle interactions, hydrodynamic forces can modify (i) S, the number fraction of particles that all SUs contain, (ii) both SUs arrangements and their internal structure, especially the SU's compactness, \\varphi. As a structural variable, S is governed by a kinetic equation. Through the shear-dependent kinetic rates involved in the latter, the general solution S depends on Γ, a dimensionless shear variable, leading to φ_{eff}(t, Γ; \\varphi). The structural modelling is achieved by introducing this expression of φ_{eff} into a well-established viscosity model of hard sphere suspensions. Using the steady state solution of the kinetic equation, S_{eq}(Γ ), allows to model non-Newtonian behaviors of complex fluids under steady shear conditions, as pseudo-plastic, plastic, dilatant ... ones. In this model, the ratio of high shear to low shear limiting viscosities appears as a key variable. Different examples of application will be discussed.

  15. Effects of an artificial gravity countermeasure on orthostatic tolerance, blood volumes and aerobic power after short-term bed rest (BR-AG1).

    PubMed

    Linnarsson, Dag; Hughson, Richard L; Fraser, Katelyn S; Clément, Gilles; Karlsson, Lars L; Mulder, Edwin; Paloski, William H; Rittweger, Jörn; Wuyts, Floris L; Zange, Jochen

    2015-01-01

    Exposure to artificial gravity (AG) in a short-arm centrifuge has potential benefits for maintaining human performance during long-term space missions. Eleven subjects were investigated during three campaigns of 5 days head-down bed rest: 1) bed rest without countermeasures (control), 2) bed rest and 30 min of AG (AG1) daily, and 3) bed rest and six periods of 5 min AG (AG2) daily. During centrifugation, the supine subjects were exposed to AG in the head-to-feet direction with 1 G at the center of mass. Subjects participated in the three campaigns in random order. The cardiovascular effects of bed rest and countermeasures were determined from changes in tolerance to a head-up tilt test with superimposed lower body negative pressure (HUT), from changes in plasma volume (PV) and from changes in maximum aerobic power (V̇o2 peak) during upright work on a cycle ergometer. Complete data sets were obtained in eight subjects. After bed rest, HUT tolerance times were 36, 64, and 78% of pre-bed rest baseline during control, AG1 and AG2, respectively, with a significant difference between AG2 and control. PV and V̇o2 peak decreased to 85 and 95% of pre-bed rest baseline, respectively, with no differences between the treatments. It was concluded that the AG2 countermeasure should be further investigated during future long-term bed rest studies, especially as it was better tolerated than AG1. The superior effect of AG2 on orthostatic tolerance could not be related to concomitant changes in PV or aerobic power. PMID:25342708

  16. Enlarged Thalamic Volumes and Increased Fractional Anisotropy in the Thalamic Radiations in Veterans with Suicide Behaviors

    PubMed Central

    Lopez-Larson, Melissa; King, Jace B.; McGlade, Erin; Bueler, Elliott; Stoeckel, Amanda; Epstein, Daniel J.; Yurgelun-Todd, Deborah

    2013-01-01

    Post-mortem studies have suggested a link between the thalamus, psychiatric disorders, and suicide. We evaluated the thalamus and anterior thalamic radiations (ATR) in a group of Veterans with and without a history of suicidal behavior (SB) to determine if thalamic abnormalities were associated with an increased risk of SB. Forty Veterans with mild traumatic brain injury (TBI) and no SB (TBI-SB), 19 Veterans with mild TBI and a history of SB (TB + SB), and 15 healthy controls (HC) underwent magnetic resonance imaging scanning including a structural and diffusion tensor imaging scan. SBs were evaluated utilizing the Columbia Suicide Rating Scale and impulsivity was measured using the Barratt Impulsiveness Scale (BIS). Differences in thalamic volumes and ATR fractional anisotropy (FA) were examined between (1) TBI + SB versus HC and (2) TBI + SB versus combined HC and TBI-SB and (3) between TBI + SB and TBI-SB. Left and right thalamic volumes were significantly increased in those with TBI + SB compared to the HC, TBI-SB, and the combined group. Veterans with TBI + SB had increased FA bilaterally compared to the HC, HC and TBI-SB group, and the TBI-SB only group. Significant positive associations were found for bilateral ATR and BIS in the TBI + SB group. Our findings of thalamic enlargement and increased FA in individuals with TBI + SB suggest that this region may be a biomarker for suicide risk. Our findings are consistent with previous evidence indicating that suicide may be associated with behavioral disinhibition and frontal-thalamic-limbic dysfunction and suggest a neurobiologic mechanism that may increase vulnerability to suicide. PMID:23964245

  17. Segmentation-based method incorporating fractional volume analysis for quantification of brain atrophy on magnetic resonance images

    NASA Astrophysics Data System (ADS)

    Wang, Deming; Doddrell, David M.

    2001-07-01

    Partial volume effect is a major problem in brain tissue segmentation on digital images such as magnetic resonance (MR) images. In this paper, special attention has been paid to partial volume effect when developing a method for quantifying brain atrophy. Specifically, partial volume effect is minimized in the process of parameter estimation prior to segmentation by identifying and excluding those voxels with possible partial volume effect. A quantitative measure for partial volume effect was also introduced through developing a model that calculates fractional volumes for voxels with mixtures of two different tissues. For quantifying cerebrospinal fluid (CSF) volumes, fractional volumes are calculated for two classes of mixture involving gray matter and CSF, and white matter and CSF. Tissue segmentation is carried out using 1D and 2D thresholding techniques after images are intensity- corrected. Threshold values are estimated using the minimum error method. Morphological processing and region identification analysis are used extensively in the algorithm. As an application, the method was employed for evaluating rates of brain atrophy based on serially acquired structural brain MR images. Consistent and accurate rates of brain atrophy have been obtained for patients with Alzheimer's disease as well as for elderly subjects due to normal aging process.

  18. Quantification of Left Ventricular Volumes, Mass and Ejection Fraction using Cine Displacement Encoding with Stimulated Echoes (DENSE) MRI

    PubMed Central

    Haggerty, Christopher M.; Kramer, Sage P.; Skrinjar, Oskar; Binkley, Cassi M.; Powell, David K.; Mattingly, Andrea C.; Epstein, Frederick H.; Fornwalt, Brandon K.

    2014-01-01

    Purpose To test the hypothesis that magnitude images from cine Displacement Encoding with Stimulated Echoes (DENSE) MRI can accurately quantify left ventricular (LV) volumes, mass, and ejection fraction. Materials and Methods Thirteen mice (C57BL/6J) were imaged using a 7T ClinScan MRI. A short-axis stack of cine T2-weighted black blood (BB) images was acquired for calculation of left ventricular volumes, mass, and ejection fraction (EF) using the gold standard sum-of-slices methodology. DENSE images were acquired during the same imaging session in three short-axis (basal, mid, apical) and two long-axis orientations. A custom surface fitting algorithm was applied to epicardial and endocardial borders from the DENSE magnitude images to calculate volumes, mass, and EF. Agreement between the DENSE-derived measures and BB-derived measures was assessed via coefficient of variation (CoV). Results 3D surface reconstruction was completed on the order of seconds from segmented images, and required fewer slices to be segmented. Volumes, mass, and EF from DENSE-derived surfaces matched well with BB data (CoVs ≤11%). Conclusion LV mass, volumes, and ejection fraction in mice can be quantified through sparse (5 slices) sampling with DENSE. This consolidation significantly reduces the time required to assess both mass/volume-based measures of cardiac function and advanced cardiac mechanics. PMID:24923710

  19. Spinal Cord Tolerance to Single-Fraction Partial-Volume Irradiation: A Swine Model

    SciTech Connect

    Medin, Paul M.; Foster, Ryan D.; Kogel, Albert J. van der; Sayre, James W.; McBride, William H.; Solberg, Timothy D.

    2011-01-01

    Purpose: To determine the spinal cord tolerance to single-fraction, partial-volume irradiation in swine. Methods and Materials: A 5-cm-long cervical segment was irradiated in 38-47-week-old Yucatan minipigs using a dedicated, image-guided radiosurgery linear accelerator. The radiation was delivered to a cylindrical volume approximately 5 cm in length and 2 cm in diameter that was positioned lateral to the cervical spinal cord, resulting in a dose distribution with the 90%, 50%, and 10% isodose lines traversing the ipsilateral, central, and contralateral spinal cord, respectively. The dose was prescribed to the 90% isodose line. A total of 26 pigs were stratified into eight dose groups of 12-47 Gy. The mean maximum spinal cord dose was 16.9 {+-} 0.1, 18.9 {+-} 0.1, 21.0 {+-} 0.1, 23.0 {+-} 0.2, and 25.3 {+-} 0.3 Gy in the 16-, 18-, 20-, 22-, and 24-Gy dose groups, respectively. The mean percentage of spinal cord volumes receiving {>=}10 Gy for the same groups were 43% {+-} 3%, 48% {+-} 4%, 51% {+-} 2%, 57% {+-} 2%, and 59% {+-} 4%. The study endpoint was motor neurologic deficit determined by a change in gait during a 1-year follow-up period. Results: A steep dose-response curve was observed with a median effective dose for the maximum dose point of 20.0 Gy (95% confidence interval, 18.3-21.7). Excellent agreement was observed between the occurrence of neurologic change and the presence of histologic change. All the minipigs with motor deficits showed some degree of demyelination and focal white matter necrosis on the irradiated side, with relative sparing of the gray matter. The histologic findings were unremarkable in the minipigs with normal neurologic status. Conclusions: Our results have indicated that for a dose distribution with a steep lateral gradient, the pigs had a lower median effective dose for paralysis than has been observed in rats and more closely resembles that for rats, mice, and guinea pigs receiving uniform spinal cord irradiation.

  20. Properties of High Volume Fraction Fly Ash/Al Alloy Composites Produced by Infiltration Process

    NASA Astrophysics Data System (ADS)

    Kountouras, D. T.; Stergioudi, F.; Tsouknidas, A.; Vogiatzis, C. A.; Skolianos, S. M.

    2015-09-01

    In the present study, pressure infiltration is employed to synthesize aluminum alloy 7075-fly ash composites. The microstructure and chemical composition of the fly ash and the produced composite material was examined using optical and scanning electron microscopy, as well as x-ray diffraction. Several properties of the produced composite material were examined and evaluated including macro-hardness, wear, thermal expansion, and corrosion behavior. The wear characteristics of the composite, in the as-cast conditions, were studied by dry sliding wear tests. The corrosion behavior of composite material was evaluated by means of potentiodynamic corrosion experiments in a 3.5 wt.% NaCl solution. The composite specimens exhibit a homogeneous distribution of fly ash particles and present enhanced hardness values, compared to the matrix material. The high volume fraction of the fly ash reinforcement (>40%) in the composite material led to increased wear rates, attributed to the fragmentation of the fly ash particles. However, the presence of fly ash particles in the Al alloy matrix considerably decreased the coefficiency of thermal expansion, while resulting in an altered corrosion mechanism of the composite material with respect to the matrix alloy.

  1. Soft nanostructured films with an ultra-low volume fraction of percolating hard phase.

    PubMed

    Chenal, Marion; Rieger, Jutta; Véchambre, Cyril; Chenal, Jean-Marc; Chazeau, Laurent; Creton, Costantino; Bouteiller, Laurent

    2013-10-01

    In this study, aqueous emulsion polymerization of n-butyl acrylate is performed in batch conditions without surfactants using a poly(acrylic acid)-trithiocarbonate macro-RAFT agent to control the polymerization and to stabilize the emulsion. According to the polymerization-induced self-assembly (PISA) approach, well-defined amphiphilic PAA-b-PBA diblock copolymers form and self-assemble during synthesis to yield highly stable core-shell particles with an extremely thin hard PAA shell. For the first time, we report here the specific properties of films obtained from these particular latexes. After drying the aqueous dispersion, tough and transparent films are obtained. Although the films are not chemically cross-linked, they do not dissolve in good solvents for PBA. Moreover, they remain transparent even after immersion in water. Rheology shows that the films are both stiff and ductile, thanks to the nanostructured but very low volume fraction (less than 3 wt%) of PAA forming a percolating network in the soft PBA. Compared with conventional core-shell-based films, this approach affords for the first time a route to a thin percolating honeycomb nanostructure with a sharp and strong interface between the two phases. The versatility of the synthetic procedure opens perspectives for a large range of functional materials.

  2. A Volume-Fraction Based Two-Phase Constitutive Model for Blood

    SciTech Connect

    Zhao, Rui; Massoudi, Mehrdad; Hund, S.J.; •Antaki, J.F.

    2008-06-01

    Mechanically-induced blood trauma such as hemolysis and thrombosis often occurs at microscopic channels, steps and crevices within cardiovascular devices. A predictive mathematical model based on a broad understanding of hemodynamics at micro scale is needed to mitigate these effects, and is the motivation of this research project. Platelet transport and surface deposition is important in thrombosis. Microfluidic experiments have previously revealed a significant impact of red blood cell (RBC)-plasma phase separation on platelet transport [5], whereby platelet localized concentration can be enhanced due to a non-uniform distribution of RBCs of blood flow in a capillary tube and sudden expansion. However, current platelet deposition models either totally ignored RBCs in the fluid by assuming a zero sample hematocrit or treated them as being evenly distributed. As a result, those models often underestimated platelet advection and deposition to certain areas [2]. The current study aims to develop a two-phase blood constitutive model that can predict phase separation in a RBC-plasma mixture at the micro scale. The model is based on a sophisticated theory known as theory of interacting continua, i.e., mixture theory. The volume fraction is treated as a field variable in this model, which allows the prediction of concentration as well as velocity profiles of both RBC and plasma phases. The results will be used as the input of successive platelet deposition models.

  3. Monomer volume fraction profiles in pH responsive planar polyelectrolyte brushes

    DOE PAGES

    Mahalik, Jyoti P.; Yang, Yubo; Deodhar, Chaitra V.; Ankner, John Francis; Lokitz, Bradley S.; Kilbey, II, S. Michael; Sumpter, Bobby G.; Kumar, Rajeev

    2016-03-06

    Spatial dependencies of monomer volume fraction profiles of pH responsive polyelectrolyte brushes were investigated using field theories and neutron reflectivity experiments. In particular, planar polyelectrolyte brushes in good solvent were studied and direct comparisons between predictions of the theories and experimental measurements are presented. The comparisons between the theories and the experimental data reveal that solvent entropy and ion-pairs resulting from adsorption of counterions from the added salt play key roles in affecting the monomer distribution and must be taken into account in modeling polyelectrolyte brushes. Furthermore, the utility of this physics-based approach based on these theories for the predictionmore » and interpretation of neutron reflectivity profiles in the context of pH responsive planar polyelectrolyte brushes such as polybasic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and polyacidic poly(methacrylic acid) (PMAA) brushes is demonstrated. The approach provides a quantitative way of estimating molecular weights of the polymers polymerized using surface-initiated atom transfer radical polymerization.« less

  4. A framework of whole heart extracellular volume fraction estimation for low dose cardiac CT images

    NASA Astrophysics Data System (ADS)

    Chen, Xinjian; Summers, Ronald M.; Nacif, Marcelo Souto; Liu, Songtao; Bluemke, David A.; Yao, Jianhua

    2012-02-01

    Cardiac magnetic resonance imaging (CMRI) has been well validated and allows quantification of myocardial fibrosis in comparison to overall mass of the myocardium. Unfortunately, CMRI is relatively expensive and is contraindicated in patients with intracardiac devices. Cardiac CT (CCT) is widely available and has been validated for detection of scar and myocardial stress/rest perfusion. In this paper, we sought to evaluate the potential of low dose CCT for the measurement of myocardial whole heart extracellular volume (ECV) fraction. A novel framework was proposed for CCT whole heart ECV estimation, which consists of three main steps. First, a shape constrained graph cut (GC) method was proposed for myocardium and blood pool segmentation for post-contrast image. Second, the symmetric Demons deformable registrations method was applied to register pre-contrast to post-contrast images. Finally, the whole heart ECV value was computed. The proposed method was tested on 7 clinical low dose CCT datasets with pre-contrast and post-contrast images. The preliminary results demonstrated the feasibility and efficiency of the proposed method.

  5. Role of cardiac CTA in estimating left ventricular volumes and ejection fraction

    PubMed Central

    Singh, Robin Man; Singh, Balkrishna Man; Mehta, Jawahar Lal

    2014-01-01

    Left ventricular ejection fraction (LVEF) is an important predictor of cardiac outcome and helps in making important diagnostic and therapeutic decisions such as the treatment of different types of congestive heart failure or implantation of devices like cardiac resynchronization therapy-defibrillator. LVEF can be measured by various techniques such as transthoracic echocardiography, contrast ventriculography, radionuclide techniques, cardiac magnetic resonance imaging and cardiac computed tomographic angiography (CTA). The development of cardiac CTA using multi-detector row CT (MDCT) has seen a very rapid improvement in the technology for identifying coronary artery stenosis and coronary artery disease in the last decade. During the acquisition, processing and analysis of data to study coronary anatomy, MDCT provides a unique opportunity to measure left ventricular volumes and LVEF simultaneously with the same data set without the need for additional contrast or radiation exposure. The development of semi-automated and automated software to measure LVEF has now added uniformity, efficiency and reproducibility of practical value in clinical practice rather than just being a research tool. This article will address the feasibility, the accuracy and the limitations of MDCT in measuring LVEF. PMID:25276310

  6. Quantitative BOLD: Mapping of Human Cerebral Deoxygenated Blood Volume and Oxygen Extraction Fraction: Default State

    PubMed Central

    He, Xiang; Yablonskiy, Dmitriy A.

    2014-01-01

    Since Ogawa et al. (Proc Natl Acad Sci USA 1990;87:9868–9872) made the fundamental discovery of blood oxygenation level-dependent (BOLD) contrast in MRI, most efforts have been directed toward the study of dynamic BOLD (i.e., temporal changes in the MRI signal during changes in brain activity). However, very little progress has been made in elucidating the nature of BOLD contrast during the resting or baseline state of the brain, which is important for understanding normal human performance because it accounts for most of the enormous energy budget of the brain. It is also crucial for deciphering the consequences of baseline-state impairment by cerebral vascular diseases. The objective of this study was to develop a BOLD MR-based method that allows quantitative evaluation of tissue hemodynamic parameters, such as the blood volume, deoxyhemoglobin concentration, and oxygen extraction fraction (OEF). The proposed method, which we have termed quantitative BOLD (qBOLD), is based on an MR signal model that incorporates prior knowledge about brain tissue composition and considers signals from gray matter (GM), white matter (WM), cerebrospinal fluid (CSF), and blood. A 2D gradient-echo sampling of spin-echo (GESSE) pulse sequence is used for the acquisition of the MRI signal. The method is applied to estimate the hemodynamic parameters of the normal human brain in the baseline state. PMID:17191227

  7. Analytical and modeling investigations of volume fraction of interfacial layers around ellipsoidal aggregate particles in multiphase materials

    NASA Astrophysics Data System (ADS)

    Xu, W. X.; Chen, H. S.

    2013-01-01

    The determination of the volume fraction of interfacial layers is very significant for assessing the quantitative relationship between the microstructure and macroscopic physical properties of complex multiphase materials. In this work, based on a three-phase composite structure, an approximate analytical model for the volume fraction of interfacial layers around ellipsoidal aggregate particles is presented in detail. To verify the accuracy and reliability of the derived analytical model, a numerical model is introduced by means of random packing of polydispersed ellipsoidal aggregate particles, in which the relative spatial position between an arbitrary point and an ellipsoidal particle is precisely and conveniently determined. With the analytical and numerical models applied, the dependence of the volume fraction of interfacial layers on various factors, such as the particle shape, the volume fraction and the maximum particle size of aggregates, and the thickness of the interfacial layers, is evaluated. Furthermore, the results from the analytical model and the numerical model with these factors are compared. It is found that the theoretical results are favorably consistent with the simulated results.

  8. High density matter in AGS, SPS and RHIC collisions: Proceedings. Volume 9

    SciTech Connect

    1998-12-01

    This 1-day workshop focused on phenomenological models regarding the specific question of the maximum energy density achievable in collisions at AGS, SPS and RHIC. The idea was to have 30-minute (or less) presentations of each model--but not the model as a whole, rather then that strongly narrowed to the above physics question. The key topics addressed were: (1) to estimate the energy density in heavy-ion collisions within a model, and to discuss its physical implications; (2) to suggest experimental observables that may confirm the correctness of a model approach--with respect to the energy density estimate; (3) to compare with existing data from AGS and SPS heavy-ion collisions, and to give predictions for the future RHIC experiments. G. Ogilvie started up the workshop with a critical summary of experimental manifestations of high-density matter at the AGS, and gave a personal outlook on RHIC physics. R. Mattiello talked about his newly developed hadron cascade model for applications to AGS and SPS collisions. Next, D. Kharzeev gave a nice introduction of the Glauber approach to high-energy collisions and illustrated the predictive power of this approach in nucleus-nucleus collisions at the SPS. It followed S. Vance with a presentation of the baryon-junction model to explain the observed baryon stopping phenomenon in collisions of heavy nuclei. S. Bass continued with a broad perspective of the UrQMD model, and provided insight into the details of the microscopic dynamical features of nuclear collisions at high energy. J. Sandweiss and J. Kapusta addressed the interesting aspect of photon production in peripherical nuclear collisions due to intense electromagnetic bremstrahlung by the highly charged, fast moving ions. Finally, H. Sorge closed up the one-day workshop with a presentation of his recent work with the RQMD model. This report consists of a summary and vugraphs of the presentations.

  9. AgRISTARS: Foreign Commodity production forecasting. Project procedures designation and description document, volume 1

    NASA Technical Reports Server (NTRS)

    Waggoner, J. T.; Phinney, D. E. (Principal Investigator)

    1981-01-01

    The crop estimation analysis procedures documentation of the AgRISTARS - Foreign Commodity Production Forecasting Project (FCPF) is presented. Specifically it includes the technical/management documentation of the remote sensing data analysis procedures prepared in accordance with the guidelines provided in the FCPF communication/documentation standards manual. Standard documentation sets are given arranged by procedural type and level then by crop types or other technically differentiating categories.

  10. Predicting Rectal and Bladder Overdose During the Course of Prostate Radiotherapy Using Dose-Volume Data From Initial Treatment Fractions

    SciTech Connect

    Murthy, Vedang; Shukla, Pragya; Adurkar, Pranjal; Master, Zubin; Mahantshetty, Umesh; Shrivastava, Shyamkishore

    2012-09-01

    Purpose: To evaluate whether information from the initial fractions can determine which patients are likely to consistently exceed their planning dose-volume constraints during the course of radiotherapy for prostate cancer. Methods and Materials: Ten patients with high-risk prostate cancer were treated with helical tomotherapy to a dose of 60 Gy in 20 fractions. The prostate, rectum, and bladder were recontoured on their daily megavoltage computed tomography scans and the dose was recalculated. The bladder and rectal volumes (in mL) receiving {>=}100% and {>=}70% of the prescribed dose in each fraction and in the original plans were recorded. A fraction for which the difference between planned and delivered was more than 2 mL was considered a volume failure. Similarly if the difference in the planned and delivered maximum dose (D{sub max}) was {>=}1% for the rectum and bladder, the fraction was considered a dose failure. Each patient's first 3 to 5 fractions were analyzed to determine if they correctly identified those patients who would consistently fail (i.e., {>=}20% of fractions) during the course of their radiotherapy. Results: Six parameters were studied; the rectal volume (RV) and bladder volumes (BV) (in mL) received {>=}100% and {>=}70% of the prescribed dose and maximum dose to 2 mL of the rectum and bladder. This was given by RV{sub 100}, RV{sub 70}, BV{sub 100}, BV{sub 70}, RD{sub max}, and BD{sub max}, respectively. When more than 1 of the first 3 fractions exceed the planning constraint as defined, it accurately predicts consistent failures through the course of the treatment. This method is able to correctly identify the consistent failures about 80% (RV{sub 70}, BV{sub 100}, and RV{sub 100}), 90% (BV{sub 70}), and 100% (RD{sub max} and BD{sub max}) of the times. Conclusions: This study demonstrates the feasibility of a method accurately identifying patients who are likely to consistently exceed the planning constraints during the course of their

  11. ECG-gated blood pool tomography in the determination of left ventricular volume, ejection fraction, and wall motion

    SciTech Connect

    Underwood, S.R.; Ell, P.J.; Jarritt, P.H.; Emanuel, R.W.; Swanton, R.H.

    1984-01-01

    ECG-gated blood pool tomography promises to provide a ''gold standard'' for noninvasive measurement of left ventricular volume, ejection fraction, and wall motion. This study compares these measurements with those from planar radionuclide imaging and contrast ventriculography. End diastolic and end systolic blood pool images were acquired tomographically using an IGE400A rotating gamma camera and Star computer, and slices were reconstructed orthogonal to the long axis of the heart. Left ventricular volume was determined by summing the areas of the slices, and wall motion was determined by comparison of end diastolic and end systolic contours. In phantom experiments this provided an accurate measurement of volume (r=0.98). In 32 subjects who were either normal or who had coronary artery disease left ventricular volume (r=0.83) and ejection fraction (r=0.89) correlated well with those using a counts based planar technique. In 16 of 18 subjects who underwent right anterior oblique X-ray contrast ventriculography, tomographic wall motion agreed for anterior, apical, and inferior walls, but abnormal septal motion which was not apparent by contrast ventriculography, was seen in 12 subjects tomographically. All 12 had disease of the left anterior descending coronary artery and might have been expected to have abnormal septal motion. ECG-gated blood pool tomography can thus determine left ventricular volume and ejection fraction accurately, and provides a global description of wall motion in a way that is not possible from any single planar image.

  12. Effect of particle volume fraction on the settling velocity of volcanic ash particles: implications for ash dispersion models

    NASA Astrophysics Data System (ADS)

    Del Bello, E.; Taddeucci, J.; De'Michieli Vitturi, M.; Scarlato, P.; Andronico, D.; Scollo, S.; Kueppers, U.

    2015-12-01

    We present the first report of experimental measurements of the enhanced settling velocity of volcanic particles as function of particle volume fraction. In order to investigate the differences in the aerodynamic behavior of ash particles when settling individually or in mass, we performed systematic large-scale ash settling experiments using natural basaltic and phonolitic ash. By releasing ash particles at different, controlled volumetric flow rates, in an unconstrained open space and at minimal air movement, we measured their terminal velocity, size, and particle volume fraction with a high-speed camera at 2000 fps. Enhanced settling velocities of individual particles increase with increasing particle volume fraction. This suggests that particle clustering during fallout may be one reason explaining larger than theoretical depletion rates of fine particles from volcanic ash clouds. We provide a quantitative empirical model that allows to calculate, from a given particle size and density, the enhanced velocity resulting from a given particle volume fraction. The proposed model has the potential to serve as a simple tool for the prediction of the terminal velocity of ash of an hypothetical distribution of ash of known particle size and volume fraction. This is of particular importance for advection-diffusion transport model of ash where generally a one-way coupling is adopted, considering only the flow effects on particles. To better quantify the importance of the enhanced settling velocity in ash dispersal, we finally introduced the new formulation in a Lagrangian model calculating for realistic eruptive conditions the resulting ash concentration in the atmosphere and on the ground.

  13. Predicting trabecular bone elastic properties from measures of bone volume fraction and fabric on the basis of micromagnetic resonance images.

    PubMed

    Wald, Michael J; Magland, Jeremy F; Rajapakse, Chamith S; Bhagat, Yusuf A; Wehrli, Felix W

    2012-08-01

    The relationship between fabric (a measure of structural anisotropy) and elastic properties of trabecular bone was examined by invoking morphology and homogenization theory on the basis of micromagnetic resonance images from the distal tibia in specimens (N = 30) and human subjects (N = 16) acquired at a 160 × 160 × 160 μm(3) voxel size. The fabric tensor was mapped in 7.5 × 7.5 × 7.5 mm(3) cubic subvolumes by a three-dimensional mean-intercept-length method. Elastic constants (three Young's and three shear moduli) were derived from linear microfinite element simulations of three-dimensional grayscale bone volume fraction-mapped images. In the specimen data, moduli fit power laws of bone volume fraction (bone volume/total volume) for all three test directions and subvolumes (R(2) = 0.92-0.98) with exponents ranging from 1.3 to 1.8. Weaker linear relationships were found for the in vivo data because of a narrower range in bone volume/total volume. When pooling the data for all test directions and subvolumes, bone volume/total volume predicted elastic moduli less well in the specimens (mean R(2) = 0.74) and not at all in vivo. A model of bone volume/total volume and fabric was highly predictive of microfinite element-derived Young's moduli: mean R(2) s of 0.98 and 0.82 (in vivo). The results show that fabric, an important predictor of bone mechanical properties, can be assessed in the limited resolution and signal-to-noise ratio regime of micromagnetic resonance images.

  14. Specimen Preparation for Metal Matrix Composites with a High Volume Fraction of Reinforcing Particles for EBSD Analysis

    NASA Astrophysics Data System (ADS)

    Smirnov, A. S.; Belozerov, G. A.; Smirnova, E. O.; Konovalov, A. V.; Shveikin, V. P.; Muizemnek, O. Yu.

    2016-07-01

    The paper deals with a procedure of preparing a specimen surface for the EBSD analysis of a metal matrix composite (MMC) with a high volume fraction of reinforcing particles. Unlike standard procedures of preparing a specimen surface for the EBSD analysis, the proposed procedure is iterative with consecutive application of mechanical and electrochemical polishing. This procedure significantly improves the results of an indexed MMC matrix in comparison with the standard procedure of specimen preparation. The procedure was verified on a MMC with pure aluminum (99.8% Al) as the matrix, SiC particles being used as reinforcing elements. The average size of the SiC particles is 14 μm, and their volume fraction amounts to 50% of the total volume of the composite. It has been experimentally found that, for making the EBSD analysis of a material matrix near reinforcing particles, the difference in height between the particles and the matrix should not exceed 2 µm.

  15. Nucleation and growth of micellar polycrystals under time-dependent volume fraction conditions

    NASA Astrophysics Data System (ADS)

    Louhichi, Ameur; Tamborini, Elisa; Ghofraniha, Neda; Caton, François; Roux, Denis; Oberdisse, Julian; Cipelletti, Luca; Ramos, Laurence

    2013-03-01

    We study the freezing kinetics of colloidal polycrystals made of micelles of Pluronic F108, a thermosensitive copolymer, to which a small amount of silica nanoparticles of a size comparable to that of the micelles are added. We use rheology and calorimetry to measure Tc, the crystallization temperature, and find that Tc increases with the heating rate Ṫ used to crystallize the sample. To rationalize our results, we first use viscosity measurements to establish a linear mapping between temperature T and the effective volume fraction, φ, of the micelles, treated as hard spheres. Next, we reproduce the experimental Ṫ dependence of the crystallization temperature with numerical calculations based on standard models for the nucleation and growth of hard-sphere crystals, classical nucleation theory and the Johnson-Mehl-Avrami-Kolmogorov theory. The models have been adapted to account for the peculiarities of our experiments: the presence of nanoparticles that are expelled in the grain boundaries and the steady increase of T and, hence, φ during the experiment. We moreover show that the polycrystal grain size obtained from the calculations is in good agreement with light microscopy data. Finally, we find that the φ dependence of the nucleation rate for the micellar polycrystal is in remarkable quantitative agreement with that found in previous experiments on colloidal hard spheres. These results suggests that deep analogies exist between hard-sphere colloidal crystals and Pluronics micellar crystals, in spite of the difference in particle softness. More generally, our results demonstrate that crystallization processes can be quantitatively probed using standard rheometry.

  16. SU-E-T-429: Uncertainties of Cell Surviving Fractions Derived From Tumor-Volume Variation Curves

    SciTech Connect

    Chvetsov, A

    2014-06-01

    Purpose: To evaluate uncertainties of cell surviving fraction reconstructed from tumor-volume variation curves during radiation therapy using sensitivity analysis based on linear perturbation theory. Methods: The time dependent tumor-volume functions V(t) have been calculated using a twolevel cell population model which is based on the separation of entire tumor cell population in two subpopulations: oxygenated viable and lethally damaged cells. The sensitivity function is defined as S(t)=[δV(t)/V(t)]/[δx/x] where δV(t)/V(t) is the time dependent relative variation of the volume V(t) and δx/x is the relative variation of the radiobiological parameter x. The sensitivity analysis was performed using direct perturbation method where the radiobiological parameter x was changed by a certain error and the tumor-volume was recalculated to evaluate the corresponding tumor-volume variation. Tumor volume variation curves and sensitivity functions have been computed for different values of cell surviving fractions from the practically important interval S{sub 2}=0.1-0.7 using the two-level cell population model. Results: The sensitivity functions of tumor-volume to cell surviving fractions achieved a relatively large value of 2.7 for S{sub 2}=0.7 and then approached zero as S{sub 2} is approaching zero Assuming a systematic error of 3-4% we obtain that the relative error in S{sub 2} is less that 20% in the range S2=0.4-0.7. This Resultis important because the large values of S{sub 2} are associated with poor treatment outcome should be measured with relatively small uncertainties. For the very small values of S2<0.3, the relative error can be larger than 20%; however, the absolute error does not increase significantly. Conclusion: Tumor-volume curves measured during radiotherapy can be used for evaluation of cell surviving fractions usually observed in radiation therapy with conventional fractionation.

  17. A preconditioned fast finite volume scheme for a fractional differential equation discretized on a locally refined composite mesh

    NASA Astrophysics Data System (ADS)

    Jia, Jinhong; Wang, Hong

    2015-10-01

    Numerical methods for fractional differential equations generate full stiffness matrices, which were traditionally solved via Gaussian type direct solvers that require O (N3) of computational work and O (N2) of memory to store where N is the number of spatial grid points in the discretization. We develop a preconditioned fast Krylov subspace iterative method for the efficient and faithful solution of finite volume schemes defined on a locally refined composite mesh for fractional differential equations to resolve boundary layers of the solutions. Numerical results are presented to show the utility of the method.

  18. Mechanical behaviors of the dispersion nuclear fuel plates induced by fuel particle swelling and thermal effect I: Effects of variations of the fuel particle volume fractions

    NASA Astrophysics Data System (ADS)

    Wang, Qiming; Yan, Xiaoqing; Ding, Shurong; Huo, Yongzhong

    2010-05-01

    A new method of modeling the in-pile mechanical behaviors of dispersion nuclear fuel elements is proposed. Considering the irradiation swelling together with the thermal effect, numerical simulations of the in-pile mechanical behaviors are performed with the developed finite element models for different fuel particle volume fractions of the fuel meat. The effects of the particle volume fractions on the mechanical performances of the fuel element are studied. The research results indicate that: (1) the maximum Mises stresses and equivalent plastic strains at the matrix increase with the particle volume fractions at each burnup; the locations of the maximum first principal stresses shift with increasing burnup; at low burnups, the maximum first principal stresses increase with the particle volume fractions; while at high burnups, the 20% volume fraction case holds the lowest value; (2) at the cladding, the maximum equivalent plastic strains and the tensile principal stresses increase with the particle volume fractions; while the maximum Mises stresses do not follow this order at high burnups; (3) the maximum Mises stresses at the fuel particles increase with the particle volume fractions, and the particles will engender plastic strains until the particle volume fraction reaches high enough.

  19. Expanded Lever Rule for Phase Volume Fraction Calculation of High-Strength Low-Alloy Steel in Thermal Simulation

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    The principle of the lever rule on the dilatation curve and its application to the corresponding differential dilatation curve were introduced in a nonoverlapped two-phase continuous cooling process. The lever rule was further expanded in the case of an overlapped two-phase process. The application of the expanded lever rule was based on the approximate symmetry treatment on the differential dilatation curve, which shows reasonably both on the theoretical calculation and in the experimental results. High-strength low-alloy steels were thermal simulated with Gleeble 3500. The transformed phase volume fractions in different cooling processes were calculated by the expanded lever rule and metallography analysis. The results showed the expanded lever rule could calculate reliable phase volume fractions as metallography analysis.

  20. FAST TRACK COMMUNICATION: Enhanced dc conductivity of low volume-fraction nano-particulate suspensions in silicone and perfluorinated oils

    NASA Astrophysics Data System (ADS)

    Wilson, S. A.; Libor, Z.; Skordos, A. A.; Zhang, Q.

    2009-03-01

    The dc conductivities of several different types of nanoparticles (nickel, barium titanate and magnetite) suspended in both silicone and perfluorinated oils have been measured and contrasted. Enhanced dc conductivity through interaction between the particles and the fluid has been demonstrated, even at quite moderate fields, and different types of nanoparticles have been shown to exhibit different behavioural trends. Whilst the dc enhancement is partly related to the concentration (or spatial arrangement) of the particles as expected, there is clear evidence that energy-activated (electric field activated) processes also play a major role. It can be said that effective-medium theories based solely on the electrical properties and volume fractions of the component materials have limited applicability when assessing the dc conductivities of these nanoparticle-fluid combinations at low volume fractions.

  1. Confidence bounds for the estimation of the volume phase fraction from a single image in a nickel base superalloy.

    PubMed

    Blanc, Rémi; Baylou, Pierre; Germain, Christian; Da Costa, Jean-Pierre

    2010-06-01

    We propose an image-based framework to evaluate the uncertainty in the estimation of the volume fraction of specific microstructures based on the observation of a single section. These microstructures consist of cubes organized on a cubic mesh, such as monocrystalline nickel base superalloys. The framework is twofold: a model-based stereological analysis allows relating two-dimensional image observations to three-dimensional microstructure features, and a spatial statistical analysis allows computing approximate confidence bounds while assessing the representativeness of the image. The reliability of the method is assessed on synthetic models. Volume fraction estimation variances and approximate confidence intervals are computed on real superalloy images in the context of material characterization. PMID:20350338

  2. Confidence bounds for the estimation of the volume phase fraction from a single image in a nickel base superalloy.

    PubMed

    Blanc, Rémi; Baylou, Pierre; Germain, Christian; Da Costa, Jean-Pierre

    2010-06-01

    We propose an image-based framework to evaluate the uncertainty in the estimation of the volume fraction of specific microstructures based on the observation of a single section. These microstructures consist of cubes organized on a cubic mesh, such as monocrystalline nickel base superalloys. The framework is twofold: a model-based stereological analysis allows relating two-dimensional image observations to three-dimensional microstructure features, and a spatial statistical analysis allows computing approximate confidence bounds while assessing the representativeness of the image. The reliability of the method is assessed on synthetic models. Volume fraction estimation variances and approximate confidence intervals are computed on real superalloy images in the context of material characterization.

  3. Diffraction efficiency of unbleached phase and amplitude holograms as a function of volume fraction of metallic silver

    NASA Astrophysics Data System (ADS)

    Madrigal, R. F.; Blaya, L. Carretero S.; Ulibarrena, M.; Beléndez, A.; Fimia, A.

    2002-01-01

    In this paper we present the theoretical and experimental study of diffraction efficiency of unbleached holograms, showing that the volume fraction of metallic silver inside the gelatin after development ( q) is the main parameter in the behavior of the holographic grating properties. Using this fact, and the obtained relationship between pH and q, we have found values of diffraction efficiencies near 30% with a developing time of 3 min without bleaching step.

  4. Blood volume, heart rate, and left ventricular ejection fraction changes in dogs before and after exercise during endurance training

    SciTech Connect

    Mackintosh, I.C.; Dormehl, I.C.; van Gelder, A.L.; du Plessis, M.

    1983-10-01

    In Beagles after 7 weeks' endurance training, resting blood volume increased by an average of 13.1%. Resting heart rates were not significantly affected, but heart rates measured 2 minutes after exercise were significantly lower after the endurance training than before. Left ventricular ejection fractions determined by radionuclide angiography from 2 minutes after exercise showed no significant changes in response to a single exercise period or over the 50 days' training.

  5. Fractionation in normal tissues: the (α/β)eff concept can account for dose heterogeneity and volume effects.

    PubMed

    Hoffmann, Aswin L; Nahum, Alan E

    2013-10-01

    The simple Linear-Quadratic (LQ)-based Withers iso-effect formula (WIF) is widely used in external-beam radiotherapy to derive a new tumour dose prescription such that there is normal-tissue (NT) iso-effect when changing the fraction size and/or number. However, as conventionally applied, the WIF is invalid unless the normal-tissue response is solely determined by the tumour dose. We propose a generalized WIF (gWIF) which retains the tumour prescription dose, but replaces the intrinsic fractionation sensitivity measure (α/β) by a new concept, the normal-tissue effective fractionation sensitivity, [Formula: see text], which takes into account both the dose heterogeneity in, and the volume effect of, the late-responding normal-tissue in question. Closed-form analytical expressions for [Formula: see text] ensuring exact normal-tissue iso-effect are derived for: (i) uniform dose, and (ii) arbitrary dose distributions with volume-effect parameter n = 1 from the normal-tissue dose-volume histogram. For arbitrary dose distributions and arbitrary n, a numerical solution for [Formula: see text] exhibits a weak dependence on the number of fractions. As n is increased, [Formula: see text] increases from its intrinsic value at n = 0 (100% serial normal-tissue) to values close to or even exceeding the tumour (α/β) at n = 1 (100% parallel normal-tissue), with the highest values of [Formula: see text] corresponding to the most conformal dose distributions. Applications of this new concept to inverse planning and to highly conformal modalities are discussed, as is the effect of possible deviations from LQ behaviour at large fraction sizes. PMID:24029492

  6. A filtration and column-adsorption system for onsite concentration and fractionation of organic substances from large volumes of water

    USGS Publications Warehouse

    Leenheer, J.A.; Noyes, T.I.

    1984-01-01

    A portable filtration and column-adsorption system which can concentrate suspended sediment and dissolved-aqueous organic substances onsite was developed. Organic solutes also are fractionated into hydrophobic- and hydrophilic-acid, base, and neutral fractions. Subsequent isolation of organic solutes from fraction concentrates and extraction of organic constituents in suspended sediment entrained on filter tubes is performed by a variety of procedures in the laboratory. Three surface-water samples and one ground-water sample ranging in volume from 300 to 1,100 liters were processed through the filtration and column-adsorption system, yielding from about 0.8 to 3.0 grams of recovered organic carbon per sample.

  7. Modeling the collagen fibril network of biological tissues as a nonlinearly elastic material using a continuous volume fraction distribution function

    PubMed Central

    Shirazi, Reza; Vena, Pasquale; Sah, Robert L.; Klisch, Stephen M.

    2012-01-01

    Despite distinct mechanical functions, biological soft tissues have a common microstructure in which a ground matrix is reinforced by a collagen fibril network. The microstructural properties of the collagen network contribute to continuum mechanical tissue properties that are strongly anisotropic with tensile-compressive asymmetry. In this study, a novel approach based on a continuous distribution of collagen fibril volume fractions is developed to model fibril reinforced soft tissues as a nonlinearly elastic and anisotropic material. Compared with other approaches that use a normalized number of fibrils for the definition of the distribution function, this representation is based on a distribution parameter (i.e. volume fraction) that is commonly measured experimentally while also incorporating pre-stress of the collagen fibril network in a tissue natural configuration. After motivating the form of the collagen strain energy function, examples are provided for two volume fraction distribution functions. Consequently, collagen second-Piola Kirchhoff stress and elasticity tensors are derived, first in general form and then specifically for a model that may be used for immature bovine articular cartilage. It is shown that the proposed strain energy is a convex function of the deformation gradient tensor and, thus, is suitable for the formation of a polyconvex tissue strain energy function. PMID:23390357

  8. The Effect of Fiber Strength Stochastics and Local Fiber Volume Fraction on Multiscale Progressive Failure of Composites

    NASA Technical Reports Server (NTRS)

    Ricks, Trenton M.; Lacy, Jr., Thomas E.; Bednarcyk, Brett A.; Arnold, Steven M.

    2013-01-01

    Continuous fiber unidirectional polymer matrix composites (PMCs) can exhibit significant local variations in fiber volume fraction as a result of processing conditions that can lead to further local differences in material properties and failure behavior. In this work, the coupled effects of both local variations in fiber volume fraction and the empirically-based statistical distribution of fiber strengths on the predicted longitudinal modulus and local tensile strength of a unidirectional AS4 carbon fiber/ Hercules 3502 epoxy composite were investigated using the special purpose NASA Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC); local effective composite properties were obtained by homogenizing the material behavior over repeating units cells (RUCs). The predicted effective longitudinal modulus was relatively insensitive to small (8%) variations in local fiber volume fraction. The composite tensile strength, however, was highly dependent on the local distribution in fiber strengths. The RUC-averaged constitutive response can be used to characterize lower length scale material behavior within a multiscale analysis framework that couples the NASA code FEAMAC and the ABAQUS finite element solver. Such an approach can be effectively used to analyze the progressive failure of PMC structures whose failure initiates at the RUC level. Consideration of the effect of local variations in constituent properties and morphologies on progressive failure of PMCs is a central aspect of the application of Integrated Computational Materials Engineering (ICME) principles for composite materials.

  9. Effects of Retained Austenite Volume Fraction, Morphology, and Carbon Content on Strength and Ductility of Nanostructured TRIP-assisted Steels

    SciTech Connect

    Shen, Yongfeng; Qiu, LN; Sun, Xin; Zuo, Liang; Liaw, Peter K.; Raabe, Dierk

    2015-06-01

    With a suite of multi-modal and multi-scale characterization techniques, the present study unambiguously proves that a substantially-improved combination of ultrahigh strength and good ductility can be achieved by tailoring the volume fraction, morphology, and carbon content of the retained austenite (RA) in a transformation-induced-plasticity (TRIP) steel with the nominal chemical composition of 0.19C-0.30Si-1.76Mn-1.52Al (weight percent, wt.%). After intercritical annealing and bainitic holding, a combination ultimate tensile strength (UTS) of 1,100 MPa and true strain of 50% has been obtained, as a result of the ultrafine RA lamellae, which are alternately arranged in the bainitic ferrite around junction regions of ferrite grains. For reference, specimens with a blocky RA, prepared without the bainitic holding, yield a low ductility (35%) and a low UTS (800 MPa). The volume fraction, morphology, and carbon content of RA have been characterized using various techniques, including magnetic probing, scanning electron microscopy (SEM), electron-backscatter-diffraction (EBSD), and transmission electron microscopy (TEM). Interrupted tensile tests, mapped using EBSD in conjunction with the kernel average misorientation (KAM) analysis, reveal that the lamellar RA is the governingmicrostructure component responsible for the higher mechanical stability, compared to the blocky one. By coupling these various techniques, we quantitatively demonstrate that in addition to the RA volume fraction, its morphology and carbon content are equally important in optimizing the strength and ductility of TRIP-assisted steels.

  10. Insight into interfacial effect on effective physical properties of fibrous materials. I. The volume fraction of soft interfaces around anisotropic fibers

    NASA Astrophysics Data System (ADS)

    Xu, Wenxiang; Wang, Han; Niu, Yanze; Bai, Jingtao

    2016-01-01

    With advances in interfacial properties characterization technologies, the interfacial volume fraction is a feasible parameter for evaluating effective physical properties of materials. However, there is a need to determine the interfacial volume fraction around anisotropic fibers and a need to assess the influence of such the interfacial property on effective properties of fibrous materials. Either ways, the accurate prediction of interfacial volume fraction is required. Towards this end, we put forward both theoretical and numerical schemes to determine the interfacial volume fraction in fibrous materials, which are considered as a three-phase composite structure consisting of matrix, anisotropic hard spherocylinder fibers, and soft interfacial layers with a constant dimension coated on the surface of each fiber. The interfacial volume fraction actually represents the fraction of space not occupied by all hard fibers and matrix. The theoretical scheme that adopts statistical geometry and stereological theories is essentially an analytic continuation from spherical inclusions. By simulating such three-phase chopped fibrous materials, we numerically derive the interfacial volume fraction. The theoretical and numerical schemes provide a quantitative insight that the interfacial volume fraction depends strongly on the fiber geometries like fiber shape, geometric size factor, and fiber size distribution. As a critical interfacial property, the present contribution can be further drawn into assessing effective physical properties of fibrous materials, which will be demonstrated in another paper (Part II) of this series.

  11. Insight into interfacial effect on effective physical properties of fibrous materials. I. The volume fraction of soft interfaces around anisotropic fibers.

    PubMed

    Xu, Wenxiang; Wang, Han; Niu, Yanze; Bai, Jingtao

    2016-01-01

    With advances in interfacial properties characterization technologies, the interfacial volume fraction is a feasible parameter for evaluating effective physical properties of materials. However, there is a need to determine the interfacial volume fraction around anisotropic fibers and a need to assess the influence of such the interfacial property on effective properties of fibrous materials. Either ways, the accurate prediction of interfacial volume fraction is required. Towards this end, we put forward both theoretical and numerical schemes to determine the interfacial volume fraction in fibrous materials, which are considered as a three-phase composite structure consisting of matrix, anisotropic hard spherocylinder fibers, and soft interfacial layers with a constant dimension coated on the surface of each fiber. The interfacial volume fraction actually represents the fraction of space not occupied by all hard fibers and matrix. The theoretical scheme that adopts statistical geometry and stereological theories is essentially an analytic continuation from spherical inclusions. By simulating such three-phase chopped fibrous materials, we numerically derive the interfacial volume fraction. The theoretical and numerical schemes provide a quantitative insight that the interfacial volume fraction depends strongly on the fiber geometries like fiber shape, geometric size factor, and fiber size distribution. As a critical interfacial property, the present contribution can be further drawn into assessing effective physical properties of fibrous materials, which will be demonstrated in another paper (Part II) of this series. PMID:26747814

  12. [Automatic calculation of left ventricular volume and ejection fraction from gated myocardial perfusion SPECT--basic evaluation using phantom].

    PubMed

    Kinoshita, Y; Nanbu, I; Tohyama, J; Ooba, S

    1998-02-01

    We evaluated accuracy of Quantitative Gated SPECT Program that enabled calculation of the left ventricular (LV) volume and ejection fraction by automatically tracing the contour of the cardiac surface. Cardiac phantoms filled with 99mTc-solution were used. Data acquisition was made by 180-degree projection in L type and 360-degree projection in opposed type. Automatic calculation could be done in all processes, which required 3-4 minutes. Reproducibility was sufficient. The adequate cut off value of a prefilter was 0.45. At this value LV volume was 93% of the actual volume in L type acquisition and 95.9% in opposed type acquisition. The LV volume obtained in L type was smaller than that obtained in opposed type (p < 0.05). The tracing of the defects was fair, on the cardiac phantoms with all of 90-degree defects and 180-degree defects of the septal and lateral wall. The LV volume was estimated to be larger on the phantom with 180-degree defect of the anterior wall, and to be smaller on the phantom of 180-degree defect of the inferoposterior wall. Because tracing was deviated anteriorly at the defects. In the patients with similar conditions to 180-degree defect of the anterior wall or inferoposterior wall, the LV volume should be carefully evaluated.

  13. Numerical simulation of effects of sand grain diameters and volume fractions on mass transferring from the water-liquid to the water-vapor

    NASA Astrophysics Data System (ADS)

    Zhao, Weiguo; Han, Xiangdong; Liu, Ming; Zheng, Yingjie

    2016-05-01

    The paper analyzed the effects of sand grain diameters and volume fractions on the mass transferring from the water-liquid to the water-vapor in a two-dimensional nozzle. Based on the mixture model, k-ɛ turbulence model and Schnerr-Sauer cavitation model, the solid-liquid-vapor three phases’ cavitation flows were simulated. When the grain mean diameters were defined as constants, volume fractions were changed to investigate the effects of them. The grain mean diameters were 0.013mm, 0.025mm and 0.05mm. Volume fractions were 0.02, 0.04, 0.05, 0.07 and 0.10. Results indicated that cavitation occurred at the beginning spots of the narrow part of the nozzle, low pressure regions. With the different grain mean diameters and volume fractions, effects of the sand on the mass transferring from the water-liquid to the water-vapor were diverse, proved by the curves of the cavitation numbers with the volume fractions of the sand and the curves of the volume fractions of the water-vapor with the volume fractions of the sand, reflecting the distinctions of interactions between the bubbles and the sand grains.

  14. Effective thermal conductivity of metal and non-metal particulate composites with interfacial thermal resistance at high volume fraction of nano to macro-sized spheres

    SciTech Connect

    Faroughi, Salah Aldin; Huber, Christian

    2015-02-07

    In this study, we propose a theoretical model to compute the effective thermal conductivity of metal and dielectric spherical particle reinforced composites with interfacial thermal resistance. We consider a wide range of filler volume fraction with sizes ranging from nano- to macro-scale. The model, based on the differential effective medium theory, accounts for particle interactions through two sets of volume fraction corrections. The first correction accounts for a finite volume of composite and the second correction introduces a self-crowding factor that allows us to develop an accurate model for particle interaction even for high volume fraction of fillers. The model is examined to other published models, experiments, and numerical simulations for different types of composites. We observe an excellent agreement between the model and published datasets over a wide range of particle volume fractions and material properties of the composite constituents.

  15. The Volume Regulation Graph versus the Ejection Fraction as Metrics of Left Ventricular Performance in Heart Failure with and without a Preserved Ejection Fraction: A Mathematical Model Study

    PubMed Central

    Faes, Theo JC; Kerkhof, Peter LM

    2015-01-01

    In left ventricular heart failure, often a distinction is made between patients with a reduced and a preserved ejection fraction (EF). As EF is a composite metric of both the end-diastolic volume (EDV) and the end-systolic ventricular volume (ESV), the lucidity of the EF is sometimes questioned. As an alternative, the ESV–EDV graph is advocated. This study identifies the dependence of the EF and the EDV–ESV graph on the major determinants of ventricular performance. Numerical simulations were made using a model of the systemic circulation, consisting of an atrium–ventricle valves combination; a simple constant pressure as venous filling system; and a three-element Windkessel extended with a venous system. ESV–EDV graphs and EFs were calculated using this model while varying one by one the filling pressure, diastolic and systolic ventricular elastances, and diastolic pressure in the aorta. In conclusion, the ESV–EDV graph separates between diastolic and systolic dysfunction while the EF encompasses these two pathologies. Therefore, the ESV–EDV graph can provide an advantage over EF in heart failure studies. PMID:26052232

  16. Optimization of the fractionated irradiation scheme considering physical doses to tumor and organ at risk based on dose–volume histograms

    SciTech Connect

    Sugano, Yasutaka; Mizuta, Masahiro; Takao, Seishin; Shirato, Hiroki; Sutherland, Kenneth L.; Date, Hiroyuki

    2015-11-15

    Purpose: Radiotherapy of solid tumors has been performed with various fractionation regimens such as multi- and hypofractionations. However, the ability to optimize the fractionation regimen considering the physical dose distribution remains insufficient. This study aims to optimize the fractionation regimen, in which the authors propose a graphical method for selecting the optimal number of fractions (n) and dose per fraction (d) based on dose–volume histograms for tumor and normal tissues of organs around the tumor. Methods: Modified linear-quadratic models were employed to estimate the radiation effects on the tumor and an organ at risk (OAR), where the repopulation of the tumor cells and the linearity of the dose-response curve in the high dose range of the surviving fraction were considered. The minimization problem for the damage effect on the OAR was solved under the constraint that the radiation effect on the tumor is fixed by a graphical method. Here, the damage effect on the OAR was estimated based on the dose–volume histogram. Results: It was found that the optimization of fractionation scheme incorporating the dose–volume histogram is possible by employing appropriate cell surviving models. The graphical method considering the repopulation of tumor cells and a rectilinear response in the high dose range enables them to derive the optimal number of fractions and dose per fraction. For example, in the treatment of prostate cancer, the optimal fractionation was suggested to lie in the range of 8–32 fractions with a daily dose of 2.2–6.3 Gy. Conclusions: It is possible to optimize the number of fractions and dose per fraction based on the physical dose distribution (i.e., dose–volume histogram) by the graphical method considering the effects on tumor and OARs around the tumor. This method may stipulate a new guideline to optimize the fractionation regimen for physics-guided fractionation.

  17. Fractional watt Vuillemier cryogenic refrigerator program engineering notebook. Volume 1: Thermal analysis

    NASA Technical Reports Server (NTRS)

    Miller, W. S.

    1974-01-01

    The cryogenic refrigerator thermal design calculations establish design approach and basic sizing of the machine's elements. After the basic design is defined, effort concentrates on matching the thermodynamic design with that of the heat transfer devices (heat exchangers and regenerators). Typically, the heat transfer device configurations and volumes are adjusted to improve their heat transfer and pressure drop characteristics. These adjustments imply that changes be made to the active displaced volumes, compensating for the influence of the heat transfer devices on the thermodynamic processes of the working fluid. Then, once the active volumes are changed, the heat transfer devices require adjustment to account for the variations in flows, pressure levels, and heat loads. This iterative process is continued until the thermodynamic cycle parameters match the design of the heat transfer devices. By examing several matched designs, a near-optimum refrigerator is selected.

  18. An improved method for simultaneous determination of frictional pressure drop and vapor volume fraction in vertical flow boiling

    NASA Technical Reports Server (NTRS)

    Klausner, J. F.; Chao, B. T.; Soo, S. L.

    1990-01-01

    The two-phase frictional pressure drop and vapor volume fraction in the vertical boiling and adiabatic flow of the refrigerant, R11, have been simultaneously measured by a liquid balancing column and differential magnetic reluctance pressure transducers. An account is given of the experimental apparatus and procedure, data acquisition and analysis, and error estimation employed. All values of two-phase multipliers evaluated on the basis of the measured frictional pressure drop data in vertical upflow fall in the range bounded by the predictions of the Chisholm correlation and the homogeneous model.

  19. Dose-Volume Response Relationship for Brain Metastases Treated with Frameless Single-Fraction Linear Accelerator-Based Stereotactic Radiosurgery

    PubMed Central

    Pan, Jianmin; Yusuf, Mehran B; Dragun, Anthony; Dunlap, Neal; Guan, Timothy; Boling, Warren; Rai, Shesh; Woo, Shiao

    2016-01-01

    Background: Our aim was to identify a dose-volume response relationship for brain metastases treated with frameless stereotactic radiosurgery (SRS). Methods: We reviewed patients who underwent frameless single-fraction linear accelerator SRS for brain metastases between 2007 and 2013 from an institutional database. Proportional hazards modeling was used to identify predictors of outcome. A ratio of maximum lesion dose per mm-diameter (Gy/mm) was constructed to establish a dose-volume relationship. Results: There were 316 metastases evaluated in 121 patients (2 - 33 mm in the largest diameter). The median peripheral dose was 18.0 Gy (range: 10.0 – 24.0 Gy). Local control was 84.8% for all lesions and was affected by location, peripheral dose, maximum dose, and lesion size (p values < 0.050). A dose-volume response relationship was constructed using the maximum dose and lesion size. A unit increase in Gy/mm was associated with decreased local failure (p = 0.005). Local control of 80%, 85%, and 90% corresponded to maximum doses per millimeter of 1.67 Gy/mm, 2.86 Gy/mm, and 4.4 Gy/mm, respectively. Toxicity was uncommon and only 1.0% of lesions developed radionecrosis requiring surgery. Conclusions: For brain metastases less than 3 cm, a dose-volume response relationship exists between maximum radiosurgical dose and lesion size, which is predictive of local control. PMID:27284495

  20. Extracellular Volume Fraction Is More Closely Associated With Altered Regional Left Ventricular Velocities Than Left Ventricular Ejection Fraction in Non-Ischemic Cardiomyopathy

    PubMed Central

    Collins, Jeremy; Sommerville, Cort; Magrath, Patrick; Spottiswoode, Bruce; Freed, Benjamin H; Benzuly, Keith H; Gordon, Robert; Vidula, Himabindu; Lee, Dan C; Yancy, Clyde; Carr, James; Markl, Michael

    2014-01-01

    Background Non-ischemic cardiomyopathy (NICM) is a common cause of left ventricular (LV) dysfunction and myocardial fibrosis. The purpose of this study was to non-invasively evaluate changes in segmental LV extracellular volume fraction (ECV), LV velocities, myocardial scar, and wall motion in NICM patients. Methods and Results Cardiac MRI including pre- and post-contrast myocardial T1-mapping and velocity quantification (tissue phase mapping, TPM) of the LV (basal, mid-ventricular, apical short axis) was applied in 31 patients with NICM (50±18years). Analysis based on the 16-segment AHA model was employed to evaluate the segmental distribution of ECV, peak systolic and diastolic myocardial velocities, scar determined by late gadolinium enhancement (LGE), and wall motion abnormalities. LV segments with scar or impaired wall motion were significantly associated with elevated ECV (r=0.26, p<0.001) and reduced peak systolic radial velocities (r=−0.43, p<0.001). Regional myocardial velocities and ECV were similar for patients with reduced (n=12, ECV=0.28±0.06) and preserved LV ejection fraction (LVEF) (n=19, ECV=0.30±0.09). Patients with preserved LVEF showed significant relationships between increasing ECV and reduced systolic (r=−0.19, r=−0.30) and diastolic (r=0.34, r=0.26) radial and long-axis peak velocities (p<0.001). Even after excluding myocardial segments with LGE, significant relationships between ECV and segmental LV velocities were maintained indicating the potential of elevated ECV to identify regional diffuse fibrosis not visible by LGE which was associated with impaired regional LV function Conclusions Regionally elevated ECV negatively impacted myocardial velocities. The association of elevated regional ECV with reduced myocardial velocities independent of LVEF suggests a structure-function relationship between altered ECV and segmental myocardial function in NICM. PMID:25552491

  1. Transmission electron microscopy convergent beam measurement of S-phase volume fraction in Al-Li-Cu-Mg-Zr alloy (8090)

    SciTech Connect

    Martin, J.W. ): Xiaoxin, X. )

    1990-12-01

    A statistical study of S-phase particle distribution in thin foils, measuring foil thickness by a transmission electron microscopy convergent beam technique, has shown the change of S-phase average length and volume fraction by varying treatments prior to artificial aging. The investigation shows that the average length and volume fraction of S-phase particles increases with increasing degrees of predeformation in the Al-Li-Cu-Mg-Zr alloy studied.

  2. A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multifrequency EM

    NASA Astrophysics Data System (ADS)

    Hoppmann, Mario; Hunkeler, Priska A.; Hendricks, Stefan; Kalscheuer, Thomas; Gerdes, Rüdiger

    2016-04-01

    In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise, accumulate beneath nearby sea ice, and subsequently form a several meter thick, porous sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator of the health of an ice shelf. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions within the platelet layer using Archie's Law. The thickness results agreed well with drillhole validation datasets within the uncertainty range, and the ice-volume fraction yielded results comparable to other studies. Both parameters together enable an estimation of the total ice volume within the platelet layer, which was found to be comparable to the volume of landfast sea ice in this region, and corresponded to more than a quarter of the annual basal melt volume of the nearby Ekström Ice Shelf. Our findings show that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties, with important implications for research into ocean/ice-shelf/sea-ice interactions. However, a successful application of this

  3. Rheological Properties of Nanoparticle Silica-Surfactant Stabilized Crude Oil Emulsions: Influence of Temperature, Nanoparticle Concentration and Water Volume Fraction"

    NASA Astrophysics Data System (ADS)

    Kinsey, Erin; Pales, Ashley; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe

    2016-04-01

    Oil in water emulsions occur during oil extraction due to the presence of water, naturally-occurring surface-active agents and mechanical mixing in pipelines or from oil spillage. Emulsions present difficulties for use of oil in fuel and their rheological properties are important to treat environmental impacts of spills. The objective of this study is to assess the rheological characteristics of oil in water emulsions stabilized by 5% NaCl brine, Tween 20 surfactant and silica nanoparticles to gain knowledge about the behavior of oil flow in pipelines and characterize them for environmental applications. Rheological behaviors such as shear rate, shear stress, and viscosity of Prudhoe Bay crude oil emulsions were analyzed with varying percent of water volume fractions (12.5, 25 and 50%), varying weight percent of silica nanoparticles (0.001, 0.01 and 0.1 weight %), with and without 2 CMC Tween 20 nonionic surfactant. Emulsions with varying water volume fractions were analyzed at 20, 40 and 60 degrees Celsius. Flow curve analysis of the emulsions was performed using an Anton-Paar rheometer. Preliminary findings indicate that increased temperature and increasing the concentration of nanoparticles both produced lower shear stress and that the addition of surfactant decreased the viscosity and shear stress of the emulsions.

  4. A Review of Thermal Conductivity of Polymer Matrix Syntactic Foams—Effect of Hollow Particle Wall Thickness and Volume Fraction

    NASA Astrophysics Data System (ADS)

    Gupta, Nikhil; Pinisetty, Dinesh

    2013-02-01

    Hollow-particle-filled composites called syntactic foams are lightweight particulate composites that are useful in weight-sensitive applications such as aerospace and marine structures. Extensive literature is now available on the mechanical properties of syntactic foams. The upcoming applications for syntactic foams in aerospace structures require understanding of their thermal properties, such as the thermal conductivity. The present review article summarizes the available experimental results and theoretical models related to the thermal conductivity of syntactic foams. Experimental results are available for only a few compositions of syntactic foams. Basic understating of the relationship between thermal conductivity of syntactic foams and the material parameters, such as hollow particle volume fraction and wall thickness, is not available through experimental results at this point. Four theoretical models are tested with the experimental data and found to provide close predictions. These models are used to conduct parametric studies. It is observed that the thermal conductivity of syntactic foams decreases as the volume fraction of thin-walled particles is increased. An inverse relationship is observed for thick-walled, hollow-particle-filled syntactic foams. These models can help in designing syntactic foams with required thermal conductivity.

  5. A probabilistic method for determining the volume fraction of pre-embedded capsules in self-healing materials

    NASA Astrophysics Data System (ADS)

    Lv, Zhong; Chen, Huisu

    2014-10-01

    Autonomous healing of cracks using pre-embedded capsules containing healing agent is becoming a promising approach to restore the strength of damaged structures. In addition to the material properties, the size and volume fraction of capsules influence crack healing in the matrix. Understanding the crack and capsule interaction is critical in the development and design of structures made of self-healing materials. Assuming that the pre-embedded capsules are randomly dispersed we theoretically model flat ellipsoidal crack interaction with capsules and determine the probability of a crack intersecting the pre-embedded capsules i.e. the self-healing probability. We also develop a probabilistic model of a crack simultaneously meeting with capsules and catalyst carriers in two-component self-healing system matrix. Using a risk-based healing approach, we determine the volume fraction and size of the pre-embedded capsules that are required to achieve a certain self-healing probability. To understand the effect of the shape of the capsules on self-healing we theoretically modeled crack interaction with spherical and cylindrical capsules. We compared the results of our theoretical model with Monte-Carlo simulations of crack interaction with capsules. The formulae presented in this paper will provide guidelines for engineers working with self-healing structures in material selection and sustenance.

  6. SU-E-T-427: Cell Surviving Fractions Derived From Tumor-Volume Variation During Radiotherapy for Non-Small Cell Lung Cancer: Comparison with Predictive Assays

    SciTech Connect

    Chvetsov, A; Schwartz, J; Mayr, N; Yartsev, S

    2014-06-01

    Purpose: To show that a distribution of cell surviving fractions S{sub 2} in a heterogeneous group of patients can be derived from tumor-volume variation curves during radiotherapy for non-small cell lung cancer. Methods: Our analysis was based on two data sets of tumor-volume variation curves for heterogeneous groups of 17 patients treated for nonsmall cell lung cancer with conventional dose fractionation. The data sets were obtained previously at two independent institutions by using megavoltage (MV) computed tomography (CT). Statistical distributions of cell surviving fractions S{sup 2} and cell clearance half-lives of lethally damaged cells T1/2 have been reconstructed in each patient group by using a version of the two-level cell population tumor response model and a simulated annealing algorithm. The reconstructed statistical distributions of the cell surviving fractions have been compared to the distributions measured using predictive assays in vitro. Results: Non-small cell lung cancer presents certain difficulties for modeling surviving fractions using tumor-volume variation curves because of relatively large fractional hypoxic volume, low gradient of tumor-volume response, and possible uncertainties due to breathing motion. Despite these difficulties, cell surviving fractions S{sub 2} for non-small cell lung cancer derived from tumor-volume variation measured at different institutions have similar probability density functions (PDFs) with mean values of 0.30 and 0.43 and standard deviations of 0.13 and 0.18, respectively. The PDFs for cell surviving fractions S{sup 2} reconstructed from tumor volume variation agree with the PDF measured in vitro. Comparison of the reconstructed cell surviving fractions with patient survival data shows that the patient survival time decreases as the cell surviving fraction increases. Conclusion: The data obtained in this work suggests that the cell surviving fractions S{sub 2} can be reconstructed from the tumor volume

  7. NiAl-base composite containing high volume fraction of AlN for advanced engines

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan (Inventor); Whittenbeger, John D. (Inventor); Lowell, Carl F. (Inventor)

    1994-01-01

    A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 to 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAlY, and FeAl.

  8. SU-E-T-480: Radiobiological Dose Comparison of Single Fraction SRS, Multi-Fraction SRT and Multi-Stage SRS of Large Target Volumes Using the Linear-Quadratic Formula

    SciTech Connect

    Ding, C; Hrycushko, B; Jiang, S; Meyer, J; Timmerman, R

    2014-06-01

    Purpose: To compare the radiobiological effect on large tumors and surrounding normal tissues from single fraction SRS, multi-fractionated SRT, and multi-staged SRS treatment. Methods: An anthropomorphic head phantom with a centrally located large volume target (18.2 cm{sup 3}) was scanned using a 16 slice large bore CT simulator. Scans were imported to the Multiplan treatment planning system where a total prescription dose of 20Gy was used for a single, three staged and three fractionated treatment. Cyber Knife treatment plans were inversely optimized for the target volume to achieve at least 95% coverage of the prescription dose. For the multistage plan, the target was segmented into three subtargets having similar volume and shape. Staged plans for individual subtargets were generated based on a planning technique where the beam MUs of the original plan on the total target volume are changed by weighting the MUs based on projected beam lengths within each subtarget. Dose matrices for each plan were export in DICOM format and used to calculate equivalent dose distributions in 2Gy fractions using an alpha beta ratio of 10 for the target and 3 for normal tissue. Results: Singe fraction SRS, multi-stage plan and multi-fractionated SRT plans had an average 2Gy dose equivalent to the target of 62.89Gy, 37.91Gy and 33.68Gy, respectively. The normal tissue within 12Gy physical dose region had an average 2Gy dose equivalent of 29.55Gy, 16.08Gy and 13.93Gy, respectively. Conclusion: The single fraction SRS plan had the largest predicted biological effect for the target and the surrounding normal tissue. The multi-stage treatment provided for a more potent biologically effect on target compared to the multi-fraction SRT treatments with less biological normal tissue than single-fraction SRS treatment.

  9. Quantitative sodium MRI of the human brain at 9.4 T provides assessment of tissue sodium concentration and cell volume fraction during normal aging.

    PubMed

    Thulborn, Keith; Lui, Elaine; Guntin, Jonathan; Jamil, Saad; Sun, Ziqi; Claiborne, Theodore C; Atkinson, Ian C

    2016-02-01

    Sodium ion homeostasis is a fundamental property of viable tissue, allowing the tissue sodium concentration to be modeled as the tissue cell volume fraction. The modern neuropathology literature using ex vivo tissue from selected brain regions indicates that human brain cell density remains constant during normal aging and attributes the volume loss that occurs with advancing age to changes in neuronal size and dendritic arborization. Quantitative sodium MRI performed with the enhanced sensitivity of ultrahigh-field 9.4 T has been used to investigate tissue cell volume fraction during normal aging. This cross-sectional study (n = 49; 21-80 years) finds that the in vivo tissue cell volume fraction remains constant in all regions of the brain with advancing age in individuals who remain cognitively normal, extending the ex vivo literature reporting constant neuronal cell density across the normal adult age range. Cell volume fraction, as measured by quantitative sodium MRI, is decreased in diseases of cell loss, such as stroke, on a time scale of minutes to hours, and in response to treatment of brain tumors on a time scale of days to weeks. Neurodegenerative diseases often have prodromal periods of decades in which regional neuronal cell loss occurs prior to clinical presentation. If tissue cell volume fraction can detect such early pathology, this quantitative parameter may permit the objective measurement of preclinical disease progression. This current study in cognitively normal aging individuals provides the basis for the pursuance of investigations directed towards such neurodegenerative diseases.

  10. The Basic Program of Vocational Agriculture in Louisiana. Ag I and Ag II (9th and 10th Grades). Volume I. Bulletin 1690-I.

    ERIC Educational Resources Information Center

    Louisiana State Dept. of Education, Baton Rouge. Div. of Vocational Education.

    This document is the first volume of a state curriculum guide on vocational agriculture for use in the 9th and 10th grades in Louisiana. Three instructional areas are profiled in this volume: orientation to vocational agriculture, agricultural leadership, and soil science. The three units of the orientation area cover introducing beginning…

  11. Nial-base composite containing high volume fraction of AlN for advanced engines

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G. (Inventor); Whittenberger, John D. (Inventor); Lowell, Carl E. (Inventor)

    1997-01-01

    A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 mm to about 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAY and FeAl.

  12. Pseudosolid, shear-thinning gel formation in binary dispersions of metal oxide nanoparticles at low volume fractions.

    PubMed

    Weston, J S; Venkataramani, D; Aichele, C P; Grady, B P; Harwell, J; Resasco, D

    2014-12-16

    Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonated depending on solution pH, changing both the magnitude and sign of the nps' surface charge. Binary mixtures of fumed metal oxide nps, dispersed in water at a solution pH where one species is positively charged and the other is negatively charged, form pseudosolid gels at volume fractions as low as 1.5 vol %. This work maps out regions of gel formation for binary mixtures of silica and alumina nps, silica and titania nps, and alumina and titania nps. The microscopic structure of these gels is investigated using transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), acoustic spectroscopy, and light microscopy.

  13. MRI measurement of oxygen extraction fraction, mean vessel size and cerebral blood volume using serial hyperoxia and hypercapnia.

    PubMed

    Germuska, Michael; Bulte, Daniel P

    2014-05-15

    Functional magnetic resonance imaging measures signal increases arising from a variety of interrelated effects and physiological sources. Recently there has been some success in disentangling this signal in order to quantify baseline physiological parameters, including the resting oxygen extraction fraction (OEF), cerebral blood volume (CBV) and mean vessel size. However, due to the complicated nature of the signal, each of these methods relies on certain physiological assumptions to derive a solution. In this work we present a framework for the simultaneous, voxelwise measurement of these three parameters. The proposed method removes the assumption of a fixed vessel size from the quantification of OEF and CBV, while simultaneously removing the need for an assumed OEF in the calculation of vessel size. The new framework is explored through simulations and validated with a pilot study in healthy volunteers. The MRI protocol uses a combined hyperoxia and hypercapnia paradigm with a modified spin labelling sequence collecting multi-slice gradient echo and spin echo data.

  14. Effect of fiber volume fraction on the off-crack-plane fracture energy in strain-hardening engineered cementitious composites

    SciTech Connect

    Maalej, M.; Hashida, Toshiyuki; Li, V.C.

    1995-12-01

    In this paper, the results of an experimental study on the effect of fiber volume fraction on the off-crack-plane fracture energy in a strain-hardening engineered cementitious composite (ECC) are presented. Unlike the well-known quasi-brittle behavior of fiber-reinforced concrete, ECC exhibits quasi-ductile response by developing a large damage zone prior to fracture localization. In the damage zone, the material is microcracked but continues to strain-harden locally. The areal dimension of the damage zone has been observed to be on the order of 1,000 cm{sup 2} in double cantilever beam specimens. The energy absorption of the off-crack-plane inelastic deformation process has been measured to be more than 50% of the total fracture energy of up to 34 kJ/m{sup 2}. This magnitude of fracture energy is the highest ever reported for a fiber cementitious composite.

  15. Quantifying uncertainty in soot volume fraction estimates using Bayesian inference of auto-correlated laser-induced incandescence measurements

    NASA Astrophysics Data System (ADS)

    Hadwin, Paul J.; Sipkens, T. A.; Thomson, K. A.; Liu, F.; Daun, K. J.

    2016-01-01

    Auto-correlated laser-induced incandescence (AC-LII) infers the soot volume fraction (SVF) of soot particles by comparing the spectral incandescence from laser-energized particles to the pyrometrically inferred peak soot temperature. This calculation requires detailed knowledge of model parameters such as the absorption function of soot, which may vary with combustion chemistry, soot age, and the internal structure of the soot. This work presents a Bayesian methodology to quantify such uncertainties. This technique treats the additional "nuisance" model parameters, including the soot absorption function, as stochastic variables and incorporates the current state of knowledge of these parameters into the inference process through maximum entropy priors. While standard AC-LII analysis provides a point estimate of the SVF, Bayesian techniques infer the posterior probability density, which will allow scientists and engineers to better assess the reliability of AC-LII inferred SVFs in the context of environmental regulations and competing diagnostics.

  16. Local shear stress and its correlation with local volume fraction in concentrated non-Brownian suspensions: lattice Boltzmann simulation.

    PubMed

    Lee, Young Ki; Ahn, Kyung Hyun; Lee, Seung Jong

    2014-12-01

    The local shear stress of non-Brownian suspensions was investigated using the lattice Boltzmann method coupled with the smoothed profile method. Previous studies have only focused on the bulk rheology of complex fluids because the local rheology of complex fluids was not accessible due to technical limitations. In this study, the local shear stress of two-dimensional solid particle suspensions in Couette flow was investigated with the method of planes to correlate non-Newtonian fluid behavior with the structural evolution of concentrated particle suspensions. Shear thickening was successfully captured for highly concentrated suspensions at high particle Reynolds number, and both the local rheology and local structure of the suspensions were analyzed. It was also found that the linear correlation between the local particle stress and local particle volume fraction was dramatically reduced during shear thickening. These results clearly show how the change in local structure of suspensions influences the local and bulk rheology of the suspensions. PMID:25615103

  17. Determination of left ventricular volume, ejection fraction, and myocardial mass by real-time three-dimensional echocardiography

    NASA Technical Reports Server (NTRS)

    Qin, J. X.; Shiota, T.; Thomas, J. D.

    2000-01-01

    Reconstructed three-dimensional (3-D) echocardiography is an accurate and reproducible method of assessing left ventricular (LV) functions. However, it has limitations for clinical study due to the requirement of complex computer and echocardiographic analysis systems, electrocardiographic/respiratory gating, and prolonged imaging times. Real-time 3-D echocardiography has a major advantage of conveniently visualizing the entire cardiac anatomy in three dimensions and of potentially accurately quantifying LV volumes, ejection fractions, and myocardial mass in patients even in the presence of an LV aneurysm. Although the image quality of the current real-time 3-D echocardiographic methods is not optimal, its widespread clinical application is possible because of the convenient and fast image acquisition. We review real-time 3-D echocardiographic image acquisition and quantitative analysis for the evaluation of LV function and LV mass.

  18. Quantifying axon diameter and intra-cellular volume fraction in excised mouse spinal cord with q-space imaging

    PubMed Central

    Ong, Henry H.; Wehrli, Felix W.

    2010-01-01

    Q-space magnetic resonance imaging (QSI) can quantify white matter (WM) axonal architecture at the cellular level non-destructively, unlike histology, but currently has several limitations. First, current methodology does not differentiate between diffusing molecules occupying extra- or intra-cellular spaces (ECS and ICS, respectively). Second, accurate assessment of axonal architecture requires high-gradient amplitudes not clinically available. Third, the only direct QSI marker of axonal architecture has been mean axon diameter (MAD), even though other direct markers would be valuable as well. The objective was to investigate three QSI-based methods that address the above limitations. Method 1 employs a two-compartment model to account for signal from ECS and ICS. Method 2 uses data only from low q-values thereby obviating the need for high-gradient amplitudes. Method 3 empirically estimates ICS volume fraction and provides an additional metric of axonal architecture. We implemented each method on data from excised healthy adult mouse spinal cords collected previously using a home-built 50T/m z-gradient yielding sub-micron displacement resolution. Through comparison with histology, each method was evaluated for accuracy in assessing axonal architecture. MAD measured with Methods 1 and 2 showed good correlation with histology (R2=0.99 (p<0.0001), and 0.77 (p<0.01), respectively) and Bland-Altman analysis indicates that measurements from the two methods are not significantly different from histology. The third method measured ICS volume fractions (0.64±0.07) that were highly correlated (R2=0.92, p<0.05) with measurements from histology (0.68±0.07). These methods may provide insight into axonal architecture in normal and abnormal WM tissue but additional validation with more samples will be needed. PMID:20350604

  19. End-systolic Pressure–Volume Relation, Ejection Fraction, and Heart Failure: Theoretical Aspect and Clinical Applications

    PubMed Central

    Shoucri, Rachad M

    2015-01-01

    A mathematical formalism describing the nonlinear end-systolic pressure–volume relation (ESPVR) is used to derive new indexes that can be used to assess the performance of the heart left ventricle by using the areas under the ESPVR (units of energy), the ordinates of the ESPVR (units of pressure), or from slopes of the curvilinear ESPVR. New relations between the ejection fraction (EF) and the parameters describing the ESPVR give some insight into the problem of heart failure (HF) with normal or preserved ejection fraction. Relations between percentage occurrence of HF and indexes derived from the ESPVR are also discussed. When ratios of pressures are used, calculation can be done in a noninvasive way with the possibility of interesting applications in routine clinical work. Applications to five groups of clinical data are given and discussed (normal group, aortic stenosis, aortic valvular regurgitation, mitral valvular regurgitation, miscellaneous cardiomyopathies). No one index allows a perfect segregation between all clinical groups, it is shown that appropriate use of two indexes (bivariate analysis) can lead to better separation of different clinical groups. PMID:26244035

  20. Recent achievements in measurements of soot volume fraction and temperatures in a coflow, diffuse Ethylene-air flame by visible image processing

    NASA Astrophysics Data System (ADS)

    Zhou, Huai-Chun; Lou, Chun; Lu, Jing

    2009-02-01

    In this review paper, the recent achievements in measurements of soot volume fraction and temperatures in a coflow, diffuse Ethylene-air flame by visible image processing are briefly outlined. For the inverse analysis of the radiative properties and temperatures, different methods show different features. The least-squares method, a regularization method and a linear programming method are all suitable for this problem, and a linear programming method can give more reasonable results. The red, green and blue flame images, which can be captured by some colour CCD camera, can be taken approximately as monochromatic images, and can be used to reconstruct temperature and soot volume fraction. But more ideal is the true monochromatic images filtered by filters at certain wavelengths. Finally, the optically-thin assumption, which is adopted widely, will cause large errors, about 100 K for temperature and 50% for soot volume fraction, as the absorption of the flame medium is neglected.

  1. The Basic Program of Vocational Agriculture in Louisiana. Ag I and Ag II (9th and 10th Grades). Volume III. Bulletin 1690-III.

    ERIC Educational Resources Information Center

    Louisiana State Dept. of Education, Baton Rouge. Div. of Vocational Education.

    This curriculum guide, the third volume of the series, outlines the basic program of vocational agriculture for Louisiana students in the ninth and tenth grades. Covered in the five units on plant science are growth processes of plants, cultural practices for plants, insects affecting plants, seed and plant selection, and diseases that affect…

  2. Quality-assured evaluation of effective porosity using fit-for-purpose estimates of clay-mineral volume fraction

    NASA Astrophysics Data System (ADS)

    Worthington, Paul F.

    2010-05-01

    Reservoirs that contain dispersed clay minerals traditionally have been evaluated petrophysically using either the effective or the total porosity system. The major weakness of the former is its reliance on "shale" volume fraction ( Vsh) as a clay-mineral indicator in the determination of effective porosity from well logs. Downhole clay-mineral indicators have usually delivered overestimates of fractional clay-mineral volume ( Vcm) because they use as a reference nearby shale beds that are often assumed to comprise clay minerals exclusively, whereas those beds also include quartzitic silts and other detritus. For this reason, effective porosity is often underestimated significantly, and this shortfall transmits to computed hydrocarbons in place and thence to estimates of ultimate recovery. The problem is overcome here by using, as proxy groundtruths, core porosities that have been upscaled to match the spatial resolutions of porosity logs. Matrix and fluid properties are established over clean intervals in the usual way. Log-derived values of Vsh are tuned so that, on average, the resulting log-derived porosities match the corresponding core porosities over an evaluation interval. In this way, Vsh is rendered fit for purpose as an indicator of clay-mineral content Vcm for purposes of evaluating effective porosity. The method is conditioned to deliver a value of effective porosity that shows overall agreement with core porosity to within the limits of uncertainty of the laboratory measurements. This is achieved through function-, reservoir- and tool-specific Vsh reduction factors that can be applied to downhole estimates of clay-mineral content over uncored intervals of similar reservoir character. As expected, the reduction factors can also vary for different measurement conditions. The reduction factors lie in the range of 0.29-0.80, which means that in its raw form, log-derived Vsh can overestimate the clay-mineral content by more than a factor of three. This

  3. Volume fraction and location of voids and gaps in ultraconservative restorations by X-ray computed micro-tomography

    PubMed Central

    Lagouvardos, Panagiotis; Nikolinakos, Nick; Oulis, Constantine

    2015-01-01

    Background: Volume fraction (Vf) and location of internal voids and gaps in relation to material type and cavity dimensions in ultraconservative restorations were investigated in this study. Materials and Methods: Forty-eight round cavities of 1.3 mm mean diameter and 2.6 mm mean depth were made on buccal and lingual surfaces of recently extracted human teeth. These were filled and thermocycled with two low viscosity composites (AeliteFlo LV [AF], PermaFlo [PF]), one high viscosity composite (Aelite aesthetic enamel [AA]) and one glass-ionomer (GCFuji IX GP). X-ray microtomography, following a specific procedure, was applied to all cavities before and after their restoration, using SkyScan-1072 microtomographer. Vf percent (Vf%) and location of voids and gaps were recorded and analysed statistically at a = 0.05. Kruskal-Wallis nonparametric analysis of variance, post-hoc analysis, Mann-Whitney test, Spearman's correlation analysis were used to analyze data. Results: Cavities filled with AF and PF showed significantly lower Vf % of voids and gaps than all other restorations (P < 0.05). Only for the cavities filled with AA, cavity width and depth was significantly correlated with Vf % (P < 0.05). 50-75% of the filled cavities contained internal voids regardless of the restorative material (P > 0.05). The proportion of cavities with gaps at the bottom and side walls was lower in those filled with AF and PF (P < 0.05). Conclusion: Cavities filled with low viscosity composites presented the lowest amount of internal voids and gaps. Glass-ionomer and high viscosity composite restorative materials showed the highest amount of interfacial gaps. Only in the high viscosity composite restorations the amount of voids and gaps correlated with the cavity depth, width and volume. PMID:26759587

  4. Simulation on simultaneous estimation of non-uniform temperature and soot volume fraction distributions in axisymmetric sooting flames

    NASA Astrophysics Data System (ADS)

    Ai, Yu-hua; Zhou, Huai-chun

    2005-02-01

    For visualizing non-uniform absorbing, emitting, non-scattering, axisymmetric sooting flames, because conventional two-color emission methods are no longer suitable, a three-color emission method for the simultaneous estimation of temperature and soot volume fraction distributions in these flames is studied in this paper. The spectral radiation intensities at wavelengths of red, green, and blue, which may be derived from color flame images, are simulated for the inverse analysis. Then the simultaneous estimation is carried out from the spectral radiation intensities by using a Newton-type iteration algorithm and the least-squares method. In this method, a factor is used to balance the wide variation of spectral radiation intensities due to both the wide ranges of temperature and wavelength of the flame radiation. The results indicate that the three-color method is suited for the reconstruction of flame structures with single or double peaks with small difference between the peak and valley. For a double-peaked flame structure with larger peak and valley difference, reasonable result can be obtained just when the mean square deviations of measurement data are small, for example, not more than 0.01.

  5. Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles.

    PubMed

    Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

    2015-01-01

    Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials.

  6. Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles

    PubMed Central

    Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

    2015-01-01

    Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials. PMID:26522701

  7. Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles.

    PubMed

    Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

    2015-01-01

    Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials. PMID:26522701

  8. Bone volume fraction and fabric anisotropy are better determinants of trabecular bone stiffness than other morphological variables.

    PubMed

    Maquer, Ghislain; Musy, Sarah N; Wandel, Jasmin; Gross, Thomas; Zysset, Philippe K

    2015-06-01

    As our population ages, more individuals suffer from osteoporosis. This disease leads to impaired trabecular architecture and increased fracture risk. It is essential to understand how morphological and mechanical properties of the cancellous bone are related. Morphology-elasticity relationships based on bone volume fraction (BV/TV) and fabric anisotropy explain up to 98% of the variation in elastic properties. Yet, other morphological variables such as individual trabeculae segmentation (ITS) and trabecular bone score (TBS) could improve the stiffness predictions. A total of 743 micro-computed tomography (μCT) reconstructions of cubic trabecular bone samples extracted from femur, radius, vertebrae, and iliac crest were analyzed. Their morphology was assessed via 25 variables and their stiffness tensor (CFE) was computed from six independent load cases using micro finite element (μFE) analyses. Variance inflation factors were calculated to evaluate collinearity between morphological variables and decide upon their inclusion in morphology-elasticity relationships. The statistically admissible morphological variables were included in a multiple linear regression model of the dependent variable CFE. The contribution of each independent variable was evaluated (ANOVA). Our results show that BV/TV is the best determinant of CFE(r(2) adj  = 0.889), especially in combination with fabric anisotropy (r(2) adj  = 0.968). Including the other independent predictors hardly affected the amount of variance explained by the model (r(2) adj  = 0.975). Across all anatomical sites, BV/TV explained 87% of the variance of the bone elastic properties. Fabric anisotropy further described 10% of the bone stiffness, but the improvement in variance explanation by adding other independent factors was marginal (<1%). These findings confirm that BV/TV and fabric anisotropy are the best determinants of trabecular bone stiffness and show, against common belief, that other

  9. Effects of Cr and B Contents on Volume Fraction of (Cr,Fe)2B and Hardness in Fe-Based Alloys Used for Powder Injection Molding

    NASA Astrophysics Data System (ADS)

    Do, Jeonghyeon; Lee, Hyuk-Joong; Jeon, Changwoo; Ha, Dae Jin; Kim, Choongnyun Paul; Lee, Byeong-Joo; Lee, Sunghak; Shin, Yang Su

    2012-07-01

    In the current study, Fe-based alloys were used for powder injection molding (PIM) parts with various qualities and hardness ranges by varying chemical compositions according to thermodynamically calculated phase diagrams. Their microstructure and hardness values were analyzed and compared with those of the PIM specimens made from conventional Fe-based alloy powders or stainless steel powders. The Cr-to-B ratio ( X Cr/ X B) and the sum of Fe, Cr, and B content ( X Fe+ X Cr+ X B) were varied to design nine Fe-based alloy compositions based on the composition of Armacor "M" alloy powders (Liquidmetal Technologies, Lake Forest, CA). According to the microstructural analysis results of the cast and heat-treated Fe-based alloys, large amounts of (Cr,Fe)2B were formed in the tempered martensite matrix. The volume fraction of (Cr,Fe)2B was varied from 42 pct to 91 pct with alloy compositions, and these results were well matched with the thermodynamically calculated volume fractions of (Cr,Fe)2B. The hardness of the fabricated alloys was varied from 300 VHN to 1600 VHN with alloy compositions, and this value increased linearly with the increasing volume fraction of (Cr,Fe)2B. From the correlation data between the volume fraction of (Cr,Fe)2B and hardness, the high-temperature equilibrium phase diagram, which could be used for the design of Fe-based alloys with various fractions and hardness values of (Cr,Fe)2B, was made.

  10. Hypervelocity Impact (HVI). Volume 8; Tile Small Targets A-1, Ag-1, B-1, and Bg-1

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Targets A-1, Ag-1, B-1, and Bg-1 was to study hypervelocity impacts on the reinforced Shuttle Heat Shield Tiles of the Wing. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  11. Assessment of vasodilator therapy in patients with severe congestive heart failure: limitations of measurements of left ventricular ejection fraction and volumes

    SciTech Connect

    Firth, B.G.; Dehmer, G.J.; Markham, R.V. Jr.; Willerson, J.T.; Hillis, L.D.

    1982-11-01

    Although noninvasive techniques are often used to assess the effect of vasodilator therapy in patients with congestive heart failure, it is unknown whether changes in noninvasively determined left ventricular ejection fraction, volume, or dimension reliably reflect alterations in intracardiac pressure and flow. Accordingly, we compared the acute effect of sodium nitroprusside on left ventricular volume and ejection fraction (determined scintigraphically) with its effect on intracardiac pressure and forward cardiac index (determined by thermodilution) in 12 patients with severe, chronic congestive heart failure and a markedly dilated left ventricle. Nitroprusside (infused at 1.3 +/- 1.1 (mean +/- standard deviation) microgram/kg/min) caused a decrease in mean systemic arterial, mean pulmonary arterial, and mean pulmonary capillary wedge pressure as well as a concomitant increase in forward cardiac index. Simultaneously, left ventricular end-diastolic and end-systolic volume indexes decreased, but the scintigraphically determined cardiac index did not change significantly. Left ventricular ejection fraction averaged 0.19 +/- 0.05 before nitroprusside administration and increased by less than 0.05 units in response to nitroprusside in 11 of 12 patients. The only significant correlation between scintigraphically and invasively determined variables was that between the percent change in end-diastolic volume index and the percent change in pulmonary capillary wedge pressure (r . 0.68, p . 0.01). Although nitroprusside produced changes in scintigraphically determined left ventricular ejection fraction, end-systolic volume index, and cardiac index, these alterations bore no predictable relation to changes in intracardiac pressure, forward cardiac index, or vascular resistance. Furthermore, nitroprusside produced a considerably greater percent change in the invasively measured variables than in the scintigraphically determined ones.

  12. A study of fiber volume fraction effects in notched unidirectional SCS-6/Ti-15V-3Cr-3Al-3Sn composite. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Covey, Steven J.

    1993-01-01

    Notched unidirectional SCS-6/Ti-15-3 composite of three different fiber volume fractions (vf = 0.15, 0.37, and 0.41) was investigated for various room temperature microstructural and material properties including: fatigue crack initiation, fatigue crack growth, and fracture toughness. While the matrix hardness is similar for all fiber volume fractions, the fiber/matrix interfacial shear strength and matrix residual stress increases with fiber volume fraction. The composite fatigue crack initiation stress is shown to be matrix controlled and occurs when the net maximum matrix stress approaches the endurance limit stress of the matrix. A model is presented which includes residual stresses and presents the composite initiation stress as a function of fiber volume fraction. This model predicts a maximum composite initiation stress at vf approximately 0.15 which agrees with the experimental data. The applied composite stress levels were increased as necessary for continued crack growth. The applied Delta(K) values at crack arrest increase with fiber volume fraction by an amount better approximated using an energy based formulation rather than when scaled linear with modulus. After crack arrest, the crack growth rate exponents for vf37 and vf41 were much lower and toughness much higher, when compared to the unreinforced matrix, because of the bridged region which parades with the propagating fatigue crack. However, the vf15 material exhibited a higher crack growth rate exponent and lower toughness than the unreinforced matrix because once the bridged fibers nearest the crack mouth broke, the stress redistribution broke all bridged fibers, leaving an unbridged crack. Degraded, unbridged behavior is modeled using the residual stress state in the matrix ahead of the crack tip. Plastic zone sizes were directly measured using a metallographic technique and allow prediction of an effective matrix stress intensity which agrees with the fiber pressure model if residual stresses

  13. Simultaneous, noninvasive measurements of convective heat transfer and solid volume fraction at the wall of an entrained gas-solid suspension

    SciTech Connect

    Griffith, A. Elizabeth; Louge, Michel; Mohd-Yusof, Jamaludin

    2000-07-01

    We describe an instrument for local, instantaneous, noninvasive, simultaneous measurements of solid volume fraction and convective heat transfer at the wall of a vertical tube containing a relatively dense, entrained suspension of gas and fine solids. The instrument combines a small platinum coil and a guarded capacitance sensor. The capacitance sensor records instantaneous solid volume fraction in the near vicinity of the wall. The coil is maintained at constant temperature by a rapid anemometer bridge circuit. The vessel is wrapped in electric heaters to avoid artificially high rates associated with developing heat transfer and to minimize conduction losses from the coil. Using a model capturing these losses, convective heat transfer rates are inferred from the power input to the coil. The instrument is tested in a cold circulating fluidized bed riser. The temporal response of the thermal sensor is faster than 30 ms. (c) 2000 American Institute of Physics.

  14. Nanoparticle volume fraction with heat and mass transfer on MHD mixed convection flow in a nanofluid in the presence of thermo-diffusion under convective boundary condition

    NASA Astrophysics Data System (ADS)

    Kandasamy, R.; Jeyabalan, C.; Sivagnana Prabhu, K. K.

    2016-02-01

    This article examines the influence of thermophoresis, Brownian motion of the nanoparticles with variable stream conditions in the presence of magnetic field on mixed convection heat and mass transfer in the boundary layer region of a semi-infinite porous vertical plate in a nanofluid under the convective boundary conditions. The transformed boundary layer ordinary differential equations are solved numerically using Maple 18 software with fourth-fifth order Runge-Kutta-Fehlberg method. Numerical results are presented both in tabular and graphical forms illustrating the effects of these parameters with magnetic field on momentum, thermal, nanoparticle volume fraction and solutal concentration boundary layers. The numerical results obtained for the velocity, temperature, volume fraction, and concentration profiles reveal interesting phenomenon, some of these qualitative results are presented through plots. It is interesting to note that the magnetic field plays a dominant role on nanofluid flow under the convective boundary conditions.

  15. Wear Behavior of Al-Mg2Si Cast In-situ Composite: Effect of Mg2Si Different Volume Fractions

    NASA Astrophysics Data System (ADS)

    Ghiasinejad, J.; Emamy, M.; Ghorbani, M. R.; Malekan, A.

    2010-06-01

    Al-Mg2Si in situ composites are great candidates for automobile brake discs due to their low density, reasonably high young's modulus and low thermal expansion coefficient. Thus, understanding wear properties of this composite is of a great importance. In this study wear behavior of an in-situ Al-Mg2Si composite, prepared from a simple casting route, has been investigated using a pin-on-disc configuration concerning the effect of Mg2Si volume fractions, 15, 20 and 25% respectively. It was found that the weight loss increases with increase in reinforce volume fraction which can be due to a coarse morphology of primary Mg2Si particles. It was found that the variations of weight loss with sliding distance comprise different regimes of which the mechanisms are discussed.

  16. Adjustable magnetoelectric effect of self-assembled vertical multiferroic nanocomposite films by the in-plane misfit strain and ferromagnetic volume fraction

    SciTech Connect

    Wu, Huaping; Chai, Guozhong; Zhou, Ting; Zhang, Zheng; Kitamura, Takayuki; Zhou, Haomiao

    2014-03-21

    The strain-mediated magnetoelectric (ME) property of self-assembled vertical multiferroic nanocomposite films epitaxially grown on cubic substrates was calculated by a nonlinear thermodynamic theory combined with the elastic theory. The dependent relations of phase state of ferroelectric films with the in-plane misfit strain, out-of-plane misfit strain, temperature, and volume fraction of ferromagnetic phase were confirmed. The effects of in-plane misfit strain and ferromagnetic volume fraction on the polarization and dielectric constant of ferroelectric films at room temperature were elaborately analyzed for the vertical BaTiO{sub 3}-CoFe{sub 2}O{sub 4} and PbTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films. Our calculated results confirmed the relationship among ME effect and in-plane misfit strain and ferromagnetic volume fraction in the nanocomposite films. The ME voltage coefficients of vertical BaTiO{sub 3}-CoFe{sub 2}O{sub 4} and PbTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films displayed various maximums and abrupt points at special phases and phase transition boundaries. The ME voltage coefficients of lead-free BaTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films epitaxially grown on different substrates could reach a comparative value of ∼2 V·cm{sup −1}·Oe{sup −1} under the controllable in-plane misfit strain induced by substrate clamping. Our results provided an available method for the optimal design of vertical multiferroic nanocomposites with adjustable ME effect by optimizing the ferromagnetic volume fraction and substrate type.

  17. Soot volume fraction measurement in low-pressure methane flames by combining laser-induced incandescence and cavity ring-down spectroscopy: Effect of pressure on soot formation

    SciTech Connect

    Desgroux, P.; Mercier, X.; Lefort, B.; Lemaire, R.; Therssen, E.; Pauwels, J.F.

    2008-10-15

    Soot volume fraction (f{sub v}) profiles are recorded in low-pressure methane/oxygen/nitrogen flat flames using laser-induced incandescence (LII). Experiments are performed from 20 to 28 kPa in flames having the same equivalence ratio (2.32). Calibration is performed by cavity ring-down spectroscopy (CRDS) and indicates a very weak soot volume fraction (0.066 ppb at 21.33 kPa and 0.8 ppb at 26.66 kPa in the burnt gases). Soot volume fraction is found to increase continuously after a given distance above the burner (HAB) and tends to level off in the burnt gases. The reaction time resolution available in low-pressure flames makes it possible to examine the early steps of soot formation. The variation of the LII signal with laser energy before the LII ''plateau'' region is much weaker at the beginning of soot formation than after a given reaction time. The LII time decays are nearly constant within the first millimetres, whereas an increase in the decay, correlated with the growth of the primary soot particle, is observed later. The growth of soot volume fraction is then analysed by considering the variation of the derivative function df{sub v}/dt with f{sub v}. Three regimes having respectively a positive slope, a constant slope, and a negative slope are observed and are interpreted with respect to the soot inception process. Finally, a very important sensitivity of f{sub v} with pressure P (at 30 mm HAB) is observed, leading to a power law, f{sub v}=KP{sup 11}, confirmed by extinction measurements (by CRDS). The observed dependence of f{sub v} with pressure could be a result of the prominence of the early soot inception process in the investigated low-pressure flames. (author)

  18. [Effect of SO2 volume fraction in flue gas on the adsorption behaviors adsorbed by ZL50 activated carbon and kinetic analysis].

    PubMed

    Gao, Ji-xian; Wang, Tie-feng; Wang, Jin-fu

    2010-05-01

    The influence of SO2 dynamic adsorption behaviors using ZL50 activated carbon for flue gas desulphurization and denitrification under different SO2 volume fraction was investigated experimentally, and the kinetic analysis was conducted by kinetic models. With the increase of SO2 volume fraction in flue gas, the SO2 removal ratio and the activity ratio of ZL50 activated carbon decreased, respectively, and SO2 adsorption rate and capacity increased correspondingly. The calculated results indicate that Bangham model has the best prediction effect, the chemisorption processes of SO2 was significantly affected by catalytic oxidative reaction. The adsorption rate constant of Lagergren's pseudo first order model increased with the increase of inlet SO, volume fraction, which indicated that catalytic oxidative reaction of SO2 adsorbed by ZL50 activated carbon may be the rate controlling step in earlier adsorption stage. The Lagergren's and Bangham's initial adsorption rate were deduced and defined, respectively. The Ho's and Elovich's initial adsorption rate were also deduced in this paper. The Bangham's initial adsorption rate values were defined in good agreement with those of experiments. The defined Bangham's adsorptive reaction kinetic model can describe the SO2 dynamic adsorption rate well. The studied results indicated that the SO2 partial order of initial reaction rate was one or adjacent to one, while the O2 and water vapor partial order of initial reaction rate were constants ranging from 0.15-0.20 and 0.45-0.50, respectively.

  19. Microcomputed tomographic analysis of human condyles in unilateral condylar hyperplasia: increased cortical porosity and trabecular bone volume fraction with reduced mineralisation.

    PubMed

    Karssemakers, L H E; Nolte, J W; Tuinzing, D B; Langenbach, G E J; Raijmakers, P G; Becking, A G

    2014-12-01

    Unilateral condylar hyperplasia or hyperactivity is a disorder of growth that affects the mandible, and our aim was to visualise the 3-dimensional bony microstructure of resected mandibular condyles of affected patients. We prospectively studied 17 patients with a clinical presentation of progressive mandibular asymmetry and an abnormal single-photon emission computed tomographic (SPECT) scan. All patients were treated by condylectomy to arrest progression. The resected condyles were scanned with micro-CT (18 μm resolution). Rectangular volumes of interest were selected in 4 quadrants (lateromedial and superoinferior) of the trabecular bone of each condyle. Variables of bone architecture (volume fraction, trabecular number, thickness, and separation, degree of mineralisation, and degree of structural anisotrophy) were calculated with routine morphometric software. Eight of the 17 resected condyles showed clear destruction of the subchondral layer of cortical bone. There was a significant superoinferior gradient for all trabecular variables. Mean (SD) bone volume fraction (25.1 (6) %), trabecular number (1.69 (0.26) mm(-1)), trabecular thickness (0.17 (0.03) mm), and degree of mineralisation (695.39 (39.83) mg HA/cm(3)) were higher in the superior region. Trabecular separation (0.6 (0.16) mm) and structural anisotropy (1.84 (0.28)) were higher in the inferior region. The micro-CT analysis showed increased cortical porosity in many of the condyles studied. It also showed a higher bone volume fraction, greater trabecular thickness and trabecular separation, greater trabecular number, and less mineralisation in the condyles of the 17 patients compared with the known architecture of unaffected mandibular condyles. PMID:25219775

  20. Global fractional anisotropy and mean diffusivity together with segmented brain volumes assemble a predictive discriminant model for young and elderly healthy brains: a pilot study at 3T

    PubMed Central

    Garcia-Lazaro, Haydee Guadalupe; Becerra-Laparra, Ivonne; Cortez-Conradis, David; Roldan-Valadez, Ernesto

    2016-01-01

    Summary Several parameters of brain integrity can be derived from diffusion tensor imaging. These include fractional anisotropy (FA) and mean diffusivity (MD). Combination of these variables using multivariate analysis might result in a predictive model able to detect the structural changes of human brain aging. Our aim was to discriminate between young and older healthy brains by combining structural and volumetric variables from brain MRI: FA, MD, and white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF) volumes. This was a cross-sectional study in 21 young (mean age, 25.71±3.04 years; range, 21–34 years) and 10 elderly (mean age, 70.20±4.02 years; range, 66–80 years) healthy volunteers. Multivariate discriminant analysis, with age as the dependent variable and WM, GM and CSF volumes, global FA and MD, and gender as the independent variables, was used to assemble a predictive model. The resulting model was able to differentiate between young and older brains: Wilks’ λ = 0.235, χ2 (6) = 37.603, p = .000001. Only global FA, WM volume and CSF volume significantly discriminated between groups. The total accuracy was 93.5%; the sensitivity, specificity and positive and negative predictive values were 91.30%, 100%, 100% and 80%, respectively. Global FA, WM volume and CSF volume are parameters that, when combined, reliably discriminate between young and older brains. A decrease in FA is the strongest predictor of membership of the older brain group, followed by an increase in WM and CSF volumes. Brain assessment using a predictive model might allow the follow-up of selected cases that deviate from normal aging. PMID:27027893

  1. {sup 11}C-methionine PET improves the target volume delineation of meningiomas treated with stereotactic fractionated radiotherapy

    SciTech Connect

    Grosu, Anca-Ligia . E-mail: anca-ligia.grosu@lrz.tum.de; Weber, Wolfgang A.; Astner, Sabrina T.; Adam, Markus; Krause, Bernd J.; Schwaiger, Markus; Molls, Michael; Nieder, Carsten

    2006-10-01

    Purpose: To evaluate the role of {sup 11}C-methionine positron emission tomography (MET-PET) in target volume delineation for meningiomas and to determine the interobserver variability. Methods and Materials: Two independent observers performed treatment planning in 10 patients according to a prospective written protocol. In the first step, they used coregistered computed tomography (CT) and magnetic resonance imaging (MRI). In the second step, MET-PET was added to CT/MRI (image fusion based on mutual information). Results: The correlation between gross tumor volume (GTVs) delineated by the two observers based on CT/MRI was r = 0.855 (Spearman's correlation coefficient, p = 0.002) and r = 0.988 (p = 0.000) when MET-PET/CT/MRI were used. The number of patients with agreement in more then 80% of the outlined volume increased with the availability of MET-PET from 1 in 10 to 5 in 10. The median volume of intersection between the regions delineated by two observers increased significantly from 69% (from the composite volume) to 79%, by the addition of MET-PET (p = 0.005). The information of MET-PET was useful to delineate GTV in the area of cavernous sinus, orbit, and base of the skull. Conclusions: The hypothesis-generating findings of potential normal tissue sparing and reduced interobserver variability provide arguments for invasive studies of the correlation between MET-PET images and histologic tumor extension and for prospective trials of target volume delineation with CT/MRI/MET-PET image fusion.

  2. Particle velocity and solid volume fraction measurements with a new capacitive flowmeter at the Solid/Gas Flow Test Facility. [Glass beads

    SciTech Connect

    Bobis, J.P.; Porges, K.G.A.; Raptis, A.C.; Brewer, W.E.; Bernovich, L.T.

    1986-08-01

    The performance of a new capacitive flowmeter has been assessed experimentally in a gas-entrained solid flow stream at the Argonne National Laboratory (ANL) Solid/Gas Flow Test Facility (S/GFTF) for solid feedrates in the range of 0.5 to 2 kg/s and solid-gas loadings up to 22, corresponding to a range of solid volume fractions extending from 0.004 to 0.016. Two types of nonintrusive instruments using the capacitive principle were fabricated at ANL and installed in the horizontal leg of a 12.3 m test section to sense the solids. An improved electrode geometry designed to maximize the coverage of the duct interior while minimizing the readout error due to a nonuniform electric field, was incorporated for one spoolpiece with the sensing electrodes on the outside surface of a ceramic liner and for another spoolpiece with the sensing electrodes mounted flush with the duct inside surface. The capacitive instruments measured the solid volume fraction and the average particle velocity. The results are compared with time-of-flight measurements of short-lived radioactive particles that duplicate closely the size and density of the 1000..mu.. glass beads used in these flow tests. Results show that the solid volume fraction measurements agree with the theoretical models presented and that the particle velocity deduced from the cross-correlation scheme agreed to within 5% of the irradiated particle velocity technique for the 21 to 31 m/s range generated with the S/GFTF. 43 refs., 36 figs., 19 tabs.

  3. Effect of volume fraction and size of fine-gamma prime particles on raising the creep strength of a DS nickel-base superalloy

    NASA Technical Reports Server (NTRS)

    Lin, D. L.; Yao, D. L.; Lin, X. J.; Sun, C. Q.

    1986-01-01

    The creep behavior of a directionally solidifified nickel-base superalloy, DKS3, has been investigated as a function of the volume fraction and size of the gamma-prime phase at 760 and 950 C. The dislocation structure and morphology of gamma-prime was examined by transmission electron microscopy at the primary, secondary and tertiary creep stages at 73.8 kgf/sq mm. Experimental results are described in terms of a high temperature creep model in the range of temperatures and applied stresses where shearing of the gamma-prime phase does not control the straining process.

  4. Thermal Cycle Stability of a Novel Glass-Mica Composite Seal for Solid Oxide Fuel Cells: Effect of Glass Volume Fraction and Stresses

    SciTech Connect

    Chou, Y S.; Stevenson, Jeffry W.; Singh, Prabhakar

    2005-12-01

    A novel glass-mica composite seal was developed based on a previously of ''infiltrated'' mica seals for solid oxide fuel cells. Ba-Al-Ca silicate sealing glass-mica composite seals. The seals were leak tested for short-term thermal cyfunction of glass volume fraction. Composite seals with 10 v% and 20 v% glatested under compressive stresses from 3 psi to 100 psi and voltage tests on dense 8YSZ electrolyte with the glas-mica composite seal showed very good thermal cycle stability.

  5. On the influence of local fluctuations in volume fraction of constituents on the effective properties of nonlinear composites. Application to porous materials

    NASA Astrophysics Data System (ADS)

    Gărăjeu, M.; Suquet, P.

    2007-04-01

    Composite materials often exhibit local fluctuations in the volume fraction of their individual constituents. This paper studies the influence of such small fluctuations on the effective properties of composites. A general asymptotic expansion of these properties in terms of powers of the amplitude of the fluctuations is given first. Then, this general result is applied to porous materials. As is well-known, the effective yield surface of ductile voided materials is accurately described by Gurson's criterion. Suitable extensions for viscoplastic solids have also been proposed. The question addressed in the present study pertains to nonuniform distributions of voids in a typical volume element or in other words to the presence of matrix-rich and pore-rich zones in the material. It is shown numerically and analytically that such deviations from a uniform distribution result in a weakening of the macroscopic carrying capacity of the material.

  6. Do X-ray determined cardiac volume and signs of congestive heart failure provide additional prognostic information after myocardial infarction if the left ventricular ejection fraction is known?

    PubMed

    Rollag, A; Mangschau, A; Jonsbu, J; Aase, O; Nerdrum, H J; Erikssen, J

    1989-04-01

    Cardiac volume (CV) was measured and indices of pulmonary congestion (PCG) were judged from routine chest films taken post myocardial infarction (AMI) in a consecutive series of 477 patients (340 first and 137 recurrent AMIs). Cardiac volume (CV) and signs of PCG were compared to left ventricular ejection fraction (LVEF), measured with isotope technique, and the prognostic value of all the parameters was assessed after 1 and 5 years. The accuracy of CV and PCG in predicting impaired LVEF was low (62% and 50% respectively). Although specificity is suboptimal, however, these parameters provided valuable prognostic information. For example, patients with signs of PCG had a very high 1 and 5 years' mortality, and two-thirds of those who died during the first year of observation had enlarged CV. The independent value of LVEF determination was mainly observed in re-AMI patients. A more restricted use of this expensive procedure may therefore be recommended. PMID:2498456

  7. Effects of particle size distribution, shape and volume fraction of aggregates on the wall effect of concrete via random sequential packing of polydispersed ellipsoidal particles

    NASA Astrophysics Data System (ADS)

    Xu, W. X.; Lv, Z.; Chen, H. S.

    2013-02-01

    Concrete can be viewed as granular materials at the mesoscopic level. A specific distribution of aggregate particles in boundary layers, known as the wall effect, plays an important role in the mechanical properties and durability of concrete. However, the detailed and systematic experimental and simulated data about the wall effect of concrete is hardly adequate yet. Specially, the modeling study of spherical and two-dimensional (2D) elliptical aggregates distribution for the wall effect has been focused on in previous work, little is known about three-dimensional (3D) ellipsoidal aggregates. In the present work, based on a mesostructure model of concrete, the wall effect of concrete is quantified by configuration parameters such as the volume fraction, the specific surface area and the meaning free spacing of the solid phase. In addition, the influences of ellipsoidal particle size distribution (EPSD), shape and volume fraction (Vf) of ellipsoidal aggregates on the configuration parameters are evaluated by stereological methods and serial section analysis technique. Furthermore, the effect mechanisms of EPSD, shape and Vf are analyzed and discussed in this paper. The reliability of the statistical results is verified by experimental data and theoretical analytical results.

  8. A novel local thresholding algorithm for trabecular bone volume fraction mapping in the limited spatial resolution regime of in vivo MRI.

    PubMed

    Vasilic, Branimir; Wehrli, Felix W

    2005-12-01

    Recent advances in micro-magnetic resonance imaging have shown the possibility of in vivo assessment of trabecular bone architecture. However, the small feature size and relatively low signal-to-noise ratio (SNR) achievable in vivo cause the intensity histogram to be unimodal. The critical first step in the processing of these images is the extraction of bone volume fraction for each voxel. Here, we propose a local threshold algorithm (LTA) that determines the marrow intensity value in the neighborhood of each voxel based on nearest-neighbor statistics. Using the local marrow intensities we threshold the image and scale the intensities of voxels partially occupied by bone to produce a marrow volume fraction map of the trabecular bone region. We show that structural parameters derived with the LTA are highly correlated with those obtained with the previously published histogram deconvolution algorithm (HDA) and that the LTA is robust to image noise corruption. The LTA is found to correctly identify trabeculae with a significantly higher reliability than HDA. Finally, we demonstrate that the LTA is superior in preserving connectivity by showing for 75 in vivo images that the genus of the trabecular bone surface is always higher than when processed with the HDA.

  9. Impact of Volume Fraction and Size of Reinforcement Particles on the Grain Size in Metal-Matrix Micro and Nanocomposites

    NASA Astrophysics Data System (ADS)

    Ferguson, J. B.; Lopez, Hugo F.; Rohatgi, Pradeep K.; Cho, Kyu; Kim, Chang-Soo

    2014-08-01

    In metal-matrix micro and nanocomposites (MMCs and MMNCs), the presence and interactions of various strengthening mechanisms are not well understood, but grain boundary strengthening is considered as one of the primary means of improving the yield strength of composites. Owing to the importance of grain size on mechanical properties, it is necessary to be able to describe how incorporation of nanoparticles (NPs) in both powder metallurgy (PM) and solidification processing (SP) affects this critical property. In the present work, we provide a basis for an empirical equation that relates particle fraction and particle size to MMNC grain size for both PM and SP synthesis methods. The model suggests that NPs retard grain coarsening in PM MMNCs and also seems to describe the effect of reinforcement concentration on grain size in SP MMCs and MMNCs.

  10. A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multi-frequency EM

    NASA Astrophysics Data System (ADS)

    Hendricks, S.; Hoppmann, M.; Hunkeler, P. A.; Kalscheuer, T.; Gerdes, R.

    2015-12-01

    In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise and accumulate beneath nearby sea ice to form a several meter thick sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator for ice - ocean interactions. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and sub-ice platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions from platelet-layer conductivities using Archie's Law. The thickness results agreed well with drill-hole validation datasets within the uncertainty range, and the ice-volume fraction also yielded plausible results. Our findings imply that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties. However, we emphasize that the successful application of this technique requires a break with traditional EM sensor calibration strategies due to the need of absolute calibration with respect to a physical forward model.

  11. Comparison of transesophageal echocardiographic and scintigraphic estimates of left ventricular end-diastolic volume index and ejection fraction in patients following coronary artery bypass grafting

    SciTech Connect

    Urbanowicz, J.H.; Shaaban, M.J.; Cohen, N.H.; Cahalan, M.K.; Botvinick, E.H.; Chatterjee, K.; Schiller, N.B.; Dae, M.W.; Matthay, M.A. )

    1990-04-01

    Transesophageal echocardiography (TEE) has become a commonly used monitor of left ventricular (LV) function and filling during cardiac surgery. Its use is based on the assumption that changes in LV short-axis ID reflect changes in LV volume. To study the ability of TEE to estimate LV volume and ejection immediately following CABG, 10 patients were studied using blood pool scintigraphy, TEE, and thermodilution cardiac output (CO). A single TEE short-axis cross-sectional image of the LV at the midpapillary muscle level was used for area analysis. Between 1 and 5 h postoperatively, simultaneous data sets (scintigraphy, TEE, and CO) were obtained three to five times in each patient. End-diastolic (EDa) and end-systolic (ESa) areas were measured by light pen. Ejection fraction area (EFa) was calculated (EFa = (EDa - ESa)/EDa). When EFa was compared with EF by scintigraphy, correlation was good (r = 0.82 SEE = 0.07). EDa was taken as an indicator of LV volume and compared with LVEDVI which was derived from EF by scintigraphy and CO. Correlation between EDa and LVEDVI was fair (r = 0.74 SEE = 3.75). The authors conclude that immediately following CABG, a single cross-sectional TEE image provides a reasonable estimate of EF but not LVEDVI.

  12. How do jet time, pressure and bone volume fraction influence the drilling depth when waterjet drilling in porcine bone?

    PubMed

    den Dunnen, Steven; Dankelman, Jenny; Kerkhoffs, Gino M M J; Tuijthof, Gabrielle J M

    2016-09-01

    Using water jets for orthopedic procedures that require bone drilling can be beneficial due to the absence of thermal damage and the always sharp cut. Previously, the influence of the water jet diameter and bone architectural properties on the drilling depth have been determined. To develop water jet instruments that can safely drill in orthopedic surgery, the impact of the two remaining primary factors were determined: the jet time (tjet [s]) and pressure (P [MPa]). To this end, 84 holes were drilled in porcine tali and femora with water jets using Ø 0.4mm nozzle. tjet was varied between 1, 3 and 5s and P between 50 and 70MPa. Drilling depths Lhole (mm), diameters Dhole (mm) and the volume of mineralized bone per unit volume (BV/TV) were determined with microCT scans. A non-linear regression analysis resulted in the predictive equation: Lhole= 0.22 * tjet(0.18) * (1.2-BV/TV) * (P-29) (R(2)=0.904). The established relation between the machine settings and drilling depth allows surgeons to adjust jet time and pressure for the patient׳s BV/TV to drill holes at a predetermined depth. For developers, the relation allows design decisions to be made that influence the dimensions, flexibility and accuracy of water jet instruments. For a pressure of 50MPa, the potential hole depth spread indicated by the 95% confidence interval is <1.6mm for all tested jet times. This maximum variance is smaller than the accuracy required for bone debridement treatments (2-4mm deep), which confirms that water jet drilling can be applied in orthopedic surgery to drill holes in bone with controlled depth.

  13. How do jet time, pressure and bone volume fraction influence the drilling depth when waterjet drilling in porcine bone?

    PubMed

    den Dunnen, Steven; Dankelman, Jenny; Kerkhoffs, Gino M M J; Tuijthof, Gabrielle J M

    2016-09-01

    Using water jets for orthopedic procedures that require bone drilling can be beneficial due to the absence of thermal damage and the always sharp cut. Previously, the influence of the water jet diameter and bone architectural properties on the drilling depth have been determined. To develop water jet instruments that can safely drill in orthopedic surgery, the impact of the two remaining primary factors were determined: the jet time (tjet [s]) and pressure (P [MPa]). To this end, 84 holes were drilled in porcine tali and femora with water jets using Ø 0.4mm nozzle. tjet was varied between 1, 3 and 5s and P between 50 and 70MPa. Drilling depths Lhole (mm), diameters Dhole (mm) and the volume of mineralized bone per unit volume (BV/TV) were determined with microCT scans. A non-linear regression analysis resulted in the predictive equation: Lhole= 0.22 * tjet(0.18) * (1.2-BV/TV) * (P-29) (R(2)=0.904). The established relation between the machine settings and drilling depth allows surgeons to adjust jet time and pressure for the patient׳s BV/TV to drill holes at a predetermined depth. For developers, the relation allows design decisions to be made that influence the dimensions, flexibility and accuracy of water jet instruments. For a pressure of 50MPa, the potential hole depth spread indicated by the 95% confidence interval is <1.6mm for all tested jet times. This maximum variance is smaller than the accuracy required for bone debridement treatments (2-4mm deep), which confirms that water jet drilling can be applied in orthopedic surgery to drill holes in bone with controlled depth. PMID:27288662

  14. Temperature, Oxygen, and Soot-Volume-Fraction Measurements in a Turbulent C2H4-Fueled Jet Flame

    SciTech Connect

    Kearney, Sean P.; Guildenbecher, Daniel Robert; Winters, Caroline; Farias, Paul Abraham; Grasser, Thomas W.; Hewson, John C.

    2015-09-01

    We present a detailed set of measurements from a piloted, sooting, turbulent C 2 H 4 - fueled diffusion flame. Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (CARS) is used to monitor temperature and oxygen, while laser-induced incandescence (LII) is applied for imaging of the soot volume fraction in the challenging jet-flame environment at Reynolds number, Re = 20,000. Single-laser shot results are used to map the mean and rms statistics, as well as probability densities. LII data from the soot-growth region of the flame are used to benchmark the soot source term for one-dimensional turbulence (ODT) modeling of this turbulent flame. The ODT code is then used to predict temperature and oxygen fluctuations higher in the soot oxidation region higher in the flame.

  15. Variability in the edible fraction content of 60Co, 99Tc, 110mAg, 137Cs and 241Am between individual crabs and lobsters from Sellafield (north eastern Irish Sea).

    PubMed

    Swift, D J; Nicholson, M D

    2001-01-01

    We investigated the variability of anthropogenic radionuclide content of the edible fractions of individual edible crabs (Cancer pagurus L.) and European lobsters (Homarus gammarus L.) caught commercially in the Sellafield offshore area. Sixteen female and 18 male crabs and 20 female and 17 male lobsters were selected from commercial catches made between 25 May and 5 June 1997. Each gender group was selected to be within the known weight range for commercially caught crustacea from the area. Four artificial radionuclides (60Co, 110mAg, 137Cs or 241Am) were detected by gamma-spectrometry. The edible fraction content of these radionuclides between males and females for either species were not statistically significantly different. 99Tc was analysed by chemical separation and beta-counting. 99Tc concentrations in female crabs tended to be higher (172 +/- 205 (16) Bq kg-1(wet); mean +/- standard deviation (n samples)) than those in males (85 +/- 58 (18) Bq kg-1 (wet)), although this was not a statistically significant difference. For both male and female crabs, 99Tc concentrations tended to decrease with increasing whole live weights. For 99Tc in lobsters the picture is less clear. Female lobsters contained more activity (14800 +/- 7400 (20) Bq kg-1 (wet)) than males (7100 +/- 3900 (17) Bq kg-1 (wet)). The results were used to discuss the implications for sampling and monitoring. PMID:11381940

  16. Effects of nano anatase-rutile TiO2 volume fraction with natural dye containing anthocyanin on the dye sensitized solar cell performance

    NASA Astrophysics Data System (ADS)

    Agustini, S.; Wahyuono, R. A.; Sawitri, D.; Risanti, D. D.

    2013-09-01

    Since its first development, efforts to improve efficiency of Dye Sensitized Solar Cell (DSSC) are continuously carried out, either through selection of dye materials, the type of semiconductor, counter electrode design or the sandwiched structure. It is widely known that anatase and rutile are phases of TiO2 that often being used for fabrication of DSSC. Rutile is thermodynamically more stable phase having band-gap suitable for absorption of sunlight spectrum. On the other hand, anatase has higher electrical conductivity, capability to adsorp dye as well as higher electron diffusion coefficient than those of rutile. Present research uses mangosteen pericarp and Rhoeo spathacea extracted in ethanol as natural dye containing anthocyanin. These dyes were characterized by using UV-Vis and FTIR, showing that the absorption maxima peaks obtained at 389 nm and 413 nm, for mangosteen and Rhoeo spathacea, respectively. The nano TiO2 was prepared by means of co-precipitation method. The particle size were 9-11 nm and 54.5 nm for anatase and rutile, respectively, according to Scherrer's equation. DSSCs were fabricated in various volume fractions of anatase and rutile TiO2. The fabricated DSSCs were tested under 17 mW/cm2 of solar irradiation. The current-voltage (I-V) characteristic of DSSCs employing 75%: 25% volume fraction of anatase and rutile TiO2 have outstanding result than others. The highest conversion efficiencies of 0.037% and 0.013% are obtained for DSSC employing natural dye extract from mangosteen pericarp and Rhoeo spathacea, respectively.

  17. Measurement of Mechanical Coherency Temperature and Solid Volume Fraction in Al-Zn Alloys Using In Situ X-ray Diffraction During Casting

    NASA Astrophysics Data System (ADS)

    Drezet, Jean-Marie; Mireux, Bastien; Kurtuldu, Güven; Magdysyuk, Oxana; Drakopoulos, Michael

    2015-09-01

    During solidification of metallic alloys, coalescence leads to the formation of solid bridges between grains or grain clusters when both solid and liquid phases are percolated. As such, it represents a key transition with respect to the mechanical behavior of solidifying alloys and to the prediction of solidification cracking. Coalescence starts at the coherency point when the grains begin to touch each other, but are unable to sustain any tensile loads. It ends up at mechanical coherency when the solid phase is sufficiently coalesced to transmit macroscopic tensile strains and stresses. Temperature at mechanical coherency is a major input parameter in numerical modeling of solidification processes as it defines the point at which thermally induced deformations start to generate internal stresses in a casting. This temperature has been determined for Al-Zn alloys using in situ X-ray diffraction during casting in a dog-bone-shaped mold. This setup allows the sample to build up internal stress naturally as its contraction is prevented. The cooling on both extremities of the mold induces a hot spot at the middle of the sample which is irradiated by X-ray. Diffraction patterns were recorded every 0.5 seconds using a detector covering a 426 × 426 mm2 area. The change of diffraction angles allowed measuring the general decrease of the lattice parameter of the fcc aluminum phase. At high solid volume fraction, a succession of strain/stress build up and release is explained by the formation of hot tears. Mechanical coherency temperatures, 829 K to 866 K (556 °C to 593 °C), and solid volume fractions, ca. 98 pct, are shown to depend on solidification time for grain refined Al-6.2 wt pct Zn alloys.

  18. A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore-fluid pressure

    USGS Publications Warehouse

    George, David L.; Iverson, Richard M.

    2011-01-01

    Pore-fluid pressure plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. Pore-pressure feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further effects of this feedback by formulating a new, depth-averaged mathematical model that simulates coupled evolution of granular dilatancy, solid and fluid volume fractions, pore-fluid pressure, and flow depth and velocity during all stages of debris-flow motion. To illustrate implications of the model, we use a finite-volume method to compute one-dimensional motion of a debris flow descending a rigid, uniformly inclined slope, and we compare model predictions with data obtained in large-scale experiments at the USGS debris-flow flume. Predictions for the first 1 s of motion show that increasing pore pressures (due to debris contraction) cause liquefaction that enhances flow acceleration. As acceleration continues, however, debris dilation causes dissipation of pore pressures, and this dissipation helps stabilize debris-flow motion. Our numerical predictions of this process match experimental data reasonably well, but predictions might be improved by accounting for the effects of grain-size segregation.

  19. Stereology of backscatter electron images of etched surfaces for characterization of particle size distributions and volume fractions: Estimation of imaging bias via Monte Carlo simulations

    SciTech Connect

    Payton, E.J. Mills, M.J.

    2011-06-15

    On metallic specimens in which a secondary phase has been selectively removed by a chemical etchant, the use of backscatter electron (BSE) imaging yields images that are more readily segmented with image processing algorithms than other modes of imaging in the scanning electron microscope. The contrast mechanisms in this imaging mode, however, produce a bias in the observation of particle sizes and volume fractions due to the effects of the electron interaction volume in the specimen. This stereological bias is quantified using Monte Carlo (MC) simulation of backscatter images. It is observed that the overprojection of features with centroids residing beneath the plane of polish is largely canceled out by the reduced segmentation size of features with centroids residing above the plane of polish. - Research Highlights: {yields} Backscatter imaging of selectively-etched surfaces can facilitate segmentation. {yields} Backscatter imaging of voids is simulated to estimate imaging/observation biases. {yields} The biases are quantified and incorporated into the stereological calculation. {yields} Systematic errors and imaging biases are observed to counteract one another. {yields} Results are illustrated using a bimodal gamma prime distribution in a Ni superalloy.

  20. T2’-Imaging to Assess Cerebral Oxygen Extraction Fraction in Carotid Occlusive Disease: Influence of Cerebral Autoregulation and Cerebral Blood Volume

    PubMed Central

    Deichmann, Ralf; Pfeilschifter, Waltraud; Hattingen, Elke; Singer, Oliver C.; Wagner, Marlies

    2016-01-01

    Purpose Quantitative T2'-mapping detects regional changes of the relation of oxygenated and deoxygenated hemoglobin (Hb) by using their different magnetic properties in gradient echo imaging and might therefore be a surrogate marker of increased oxygen extraction fraction (OEF) in cerebral hypoperfusion. Since elevations of cerebral blood volume (CBV) with consecutive accumulation of Hb might also increase the fraction of deoxygenated Hb and, through this, decrease the T2’-values in these patients we evaluated the relationship between T2’-values and CBV in patients with unilateral high-grade large-artery stenosis. Materials and Methods Data from 16 patients (13 male, 3 female; mean age 53 years) with unilateral symptomatic or asymptomatic high-grade internal carotid artery (ICA) or middle cerebral artery (MCA) stenosis/occlusion were analyzed. MRI included perfusion-weighted imaging and high-resolution T2’-mapping. Representative relative (r)CBV-values were analyzed in areas of decreased T2’ with different degrees of perfusion delay and compared to corresponding contralateral areas. Results No significant elevations in cerebral rCBV were detected within areas with significantly decreased T2’-values. In contrast, rCBV was significantly decreased (p<0.05) in regions with severe perfusion delay and decreased T2’. Furthermore, no significant correlation between T2’- and rCBV-values was found. Conclusions rCBV is not significantly increased in areas of decreased T2’ and in areas of restricted perfusion in patients with unilateral high-grade stenosis. Therefore, T2’ should only be influenced by changes of oxygen metabolism, regarding our patient collective especially by an increase of the OEF. T2’-mapping is suitable to detect altered oxygen consumption in chronic cerebrovascular disease. PMID:27560515

  1. Simultaneous changes in gray matter volume and white matter fractional anisotropy in Alzheimer's disease revealed by multimodal CCA and joint ICA.

    PubMed

    Ouyang, X; Chen, K; Yao, L; Hu, B; Wu, X; Ye, Q; Guo, X

    2015-08-20

    The prominent morphometric alterations of Alzheimer's disease (AD) occur both in gray matter and in white matter. Multimodal fusion can examine joint information by combining multiple neuroimaging datasets to identify the covariant morphometric alterations in AD in greater detail. In the current study, we conducted a multimodal canonical correlation analysis and joint independent component analysis to identify the covariance patterns of the gray and white matter by fusing structural magnetic resonance imaging and diffusion tensor imaging data of 39 AD patients (23 males and 16 females, mean age: 74.91±8.13years) and 41 normal controls (NCs) (20 males and 21 females, mean age: 73.97±6.34years) derived from the Alzheimer's Disease Neuroimaging Initiative database. The results revealed 25 joint independent components (ICs), of which three joint ICs exhibited strong links between the gray matter volume and the white matter fractional anisotropy (FA) and significant differences between the AD and NC group. The joint IC maps revealed that the simultaneous changes in the gray matter and FA values primarily involved the following areas: (1) the temporal lobe/hippocampus-cingulum, (2) the frontal/cingulate gyrus-corpus callosum, and (3) the temporal/occipital/parietal lobe-corpus callosum/corona radiata. Our findings suggest that gray matter atrophy is associated with reduced white matter fiber integrity in AD and possibly expand the understanding of the neuropathological mechanisms in AD.

  2. Performance of a hydrogen burner to simulate air entering scramjet combustors. [simulation of total temperature, total pressure, and volume fraction of oxygen of air at flight conditions

    NASA Technical Reports Server (NTRS)

    Russin, W. R.

    1974-01-01

    Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.

  3. Large-scale three-dimensional phase-field simulations for phase coarsening at ultrahigh volume fraction on high-performance architectures

    NASA Astrophysics Data System (ADS)

    Yan, Hui; Wang, K. G.; Jones, Jim E.

    2016-06-01

    A parallel algorithm for large-scale three-dimensional phase-field simulations of phase coarsening is developed and implemented on high-performance architectures. From the large-scale simulations, a new kinetics in phase coarsening in the region of ultrahigh volume fraction is found. The parallel implementation is capable of harnessing the greater computer power available from high-performance architectures. The parallelized code enables increase in three-dimensional simulation system size up to a 5123 grid cube. Through the parallelized code, practical runtime can be achieved for three-dimensional large-scale simulations, and the statistical significance of the results from these high resolution parallel simulations are greatly improved over those obtainable from serial simulations. A detailed performance analysis on speed-up and scalability is presented, showing good scalability which improves with increasing problem size. In addition, a model for prediction of runtime is developed, which shows a good agreement with actual run time from numerical tests.

  4. Effect of anatomical noise on the detectability of cone beam CT images with different slice direction, slice thickness, and volume glandular fraction.

    PubMed

    Han, Minah; Park, Subok; Baek, Jongduk

    2016-08-22

    We investigate the effect of anatomical noise on the detectability of cone beam CT (CBCT) images with different slice directions, slice thicknesses, and volume glandular fractions (VGFs). Anatomical noise is generated using a power law spectrum of breast anatomy, and spherical objects with diameters from 1mm to 11mm are used as breast masses. CBCT projection images are simulated and reconstructed using the FDK algorithm. A channelized Hotelling observer (CHO) with Laguerre-Gauss (LG) channels is used to evaluate detectability for the signal-known-exactly (SKE) binary detection task. Detectability is calculated for various slice thicknesses in the transverse and longitudinal planes for 15%, 30% and 60% VGFs. The optimal slice thicknesses that maximize the detectability of the objects are determined. The results show that the β value increases as the slice thickness increases, but that thicker slices yield higher detectability in the transverse and longitudinal planes, except for the case of a 1mm diameter spherical object. It is also shown that the longitudinal plane with a 0.1mm slice thickness provides higher detectability than the transverse plane, despite its higher β value. With optimal slice thicknesses, the longitudinal plane exhibits better detectability for all VGFs and spherical objects. PMID:27557168

  5. Accuracy of relocation, evaluation of geometric uncertainties and clinical target volume (CTV) to planning target volume (PTV) margin in fractionated stereotactic radiotherapy for intracranial tumors using relocatable Gill-Thomas-Cosman (GTC) frame.

    PubMed

    Das, Saikat; Isiah, Rajesh; Rajesh, B; Ravindran, B Paul; Singh, Rabi Raja; Backianathan, Selvamani; Subhashini, J

    2011-01-01

    The present study is aimed at determination of accuracy of relocation of Gill-Thomas-Cosman frame during fractionated stereotactic radiotherapy. The study aims to quantitatively determine the magnitudes of error in anteroposterior, mediolateral and craniocaudal directions, and determine the margin between clinical target volume to planning target volume based on systematic and random errors. Daily relocation error was measured using depth helmet and measuring probe. Based on the measurements, translational displacements in anteroposterior (z), mediolateral (x), and craniocaudal (y) directions were calculated. Based on the displacements in x, y and z directions, systematic and random error were calculated and three-dimensional radial displacement vector was determined. Systematic and random errors were used to derive CTV to PTV margin. The errors were within ± 2 mm in 99.2% cases in anteroposterior direction (AP), in 99.6% cases in mediolateral direction (ML), and in 97.6% cases in craniocaudal direction (CC). In AP, ML and CC directions, systematic errors were 0.56, 0.38, 0.42 mm and random errors were 1.86, 1.36 and 0.73 mm, respectively. Mean radial displacement was 1.03 mm ± 0.34. CTV to PTV margins calculated by ICRU formula were 1.86, 1.45 and 0.93 mm; by Stroom's formula they were 2.42, 1.74 and 1.35 mm; by van Herk's formula they were 2.7, 1.93 and 1.56 mm (AP, ML and CC directions). Depth helmet with measuring probe provides a clinically viable way for assessing the relocation accuracy of GTC frame. The errors were within ± 2 mm in all directions. Systematic and random errors were more along the anteroposterior axes. According to the ICRU formula, a margin of 2 mm around the tumor seems to be adequate. PMID:21587166

  6. Correction to "What is a fractional derivative?" by Ortigueira and Machado [Journal of Computational Physics, Volume 293, 15 July 2015, Pages 4-13. Special issue on Fractional PDEs

    NASA Astrophysics Data System (ADS)

    Katugampola, Udita N.

    2016-09-01

    There is a debate among contemporary mathematicians about what it really means by a fractional derivative. The question arose as a consequence of introducing a 'new' definition of a fractional derivative in [1]. In a reply, Ortigueira and Machado [2] came up with several very important criteria to determine whether a given derivative is a fractional derivative. According to their criterion, the new fractional derivative, called conformable fractional derivative, introduced by Khalil et al. [1] turns out not to be a fractional derivative, but rather a controlled or conformable derivative. In proving the claim the authors in [2] use an example [2, p. 6]. It turns out that the explanation given there needs some corrections and it is the sole purpose of this note.

  7. Characterization of the intermediate-range order in new superionic conducting AgI-Ag2S-AgPO3 glasses by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Kartini, E.; Kennedy, S. J.; Itoh, K.; Fukunaga, T.; Suminta, S.; Kamiyama, T.

    Superionic conducting glasses are of considerable technological interest because of their use in batteries, sensors, and displays. We have investigated the new ternary systems AgI-Ag2S-AgPO3 where the ratio AgI:Ag2S is 1:1. The system (AgI)x(Ag2S)x(AgPO3)1-2x, for a AgI+Ag2S fraction less than 82mol%, yields glasses. We have used a neutron-diffraction technique to obtain the total scattering structure factor S(Q) of this system at room temperature by using the HIT spectrometer at the High Energy Accelerator (KEK), Tsukuba, Japan. As for AgI-AgPO3 glasses, S(Q) shows a peak at anomalously low Q in the range from 0.6 to 0.9 Å-1. This peak is not observed in the corresponding glass Ag2S-AgPO3 or pure AgPO3. The peak depends strongly on the dopant salt. Its intensity increases as the amount of (AgI+Ag2S) increases and its position shifts to lower Q, while the number density of the glasses decreases with x. This peak can be associated with an intermediate structure of particles lying inside a continuous host with the characteristic length between 5 and 10 Å [1].

  8. Comparison of ejection fraction and pulmonary blood volume ratio as markers of left ventricular dysfunction with single vessel coronary disease before and after PTCA

    SciTech Connect

    Liu, P.; Kiess, M.; Okada, R.D.; Boucher, C.A.; Strauss, H.W.

    1984-01-01

    Exercise induced increases in pulmonary blood volume (PBV) have been shown to correlate with transient exercised-induced increase in left ventricular (LV) filling pressure. To analyze the impact of single vessel disease on LV function, ejection fraction (EF) and PBV were measured by serial supine exercise gated scans (GBPS) on 53 patients with left anterior descending artery disease undergoing coronary angioplasty (PTCA). EF was defined by standard methods. The PBV ratio was taken as the exercise to rest counts from the lung regions of interest as previously reported. Regional wall motion (WM) was quantified by averaging the results of 5-point score system in each region from 3 observers. Normal was defined as: rest EF greater than or equal to .50 and increase in EF with exercise, PBV less than or equal to 1.06 and no deterioration in WM on exercise. Of the 53 patients, 54% were found to be abnormal by EF, but 83% by PBV (p<.01). Abnormal PBV ratio was also highly associated with exercise induced deterioration in WM on GBPS (p<.05). After PTCA, the proportion of patients with abnormal EF remained unchanged (50%), whereas those with abnormal PBV ratio decreased significantly (to 38%, p<0.01). The authors conclude: (1) PBV ratio (filling pressures) is more frequently abnormal than EF (systolic function) in single vessel disease; (2) There is a significant improvement of PBV ratio after PTGA; (3) This discordance of parameters of systolic and diastolic function suggests that PBV (and hence diastolic function) is a more sensitive indicator of changes in ventricular function following an intervention than EF.

  9. Myocardial Extracellular Volume Fraction with Dual-Energy Equilibrium Contrast-enhanced Cardiac CT in Nonischemic Cardiomyopathy: A Prospective Comparison with Cardiac MR Imaging.

    PubMed

    Lee, Hye-Jeong; Im, Dong Jin; Youn, Jong-Chan; Chang, Suyon; Suh, Young Joo; Hong, Yoo Jin; Kim, Young Jin; Hur, Jin; Choi, Byoung Wook

    2016-07-01

    Purpose To evaluate the feasibility of equilibrium contrast material-enhanced dual-energy cardiac computed tomography (CT) to determine extracellular volume fraction (ECV) in nonischemic cardiomyopathy (CMP) compared with magnetic resonance (MR) imaging. Materials and Methods This study was approved by the institutional review board; informed consent was obtained. Seven healthy subjects and 23 patients (six with hypertrophic CMP, nine with dilated CMP, four with amyloidosis, and four with sarcoidosis) (mean age ± standard deviation, 57.33 years ± 14.82; 19 male participants [63.3%]) were prospectively enrolled. Twelve minutes after contrast material injection (1.8 mL/kg at 3 mL/sec), dual-energy cardiac CT was performed. ECV was measured by two observers independently. Hematocrit levels were compared between healthy subjects and patients with the Mann-Whitney U test. In per-subject analysis, interobserver agreement for CT was assessed with the intraclass correlation coefficient (ICC), and intertest agreement between MR imaging and CT was assessed with Bland-Altman analysis. In per-segment analysis, Student t tests in the linear mixed model were used to compare ECV on CT images between healthy subjects and patients. Results Hematocrit level was 43.44% ± 1.80 for healthy subjects and 41.23% ± 5.61 for patients with MR imaging (P = .16) and 43.50% ± 1.92 for healthy subjects and 41.35% ± 5.92 for patients with CT (P = .15). For observer 1 in per-subject analysis, ECV was 34.18% ± 8.98 for MR imaging and 34.48% ± 8.97 for CT. For observer 2, myocardial ECV was 34.42% ± 9.03 for MR imaging and 33.98% ± 9.05 for CT. Interobserver agreement for ECV at CT was excellent (ICC = 0.987). Bland-Altman analysis between MR imaging and CT showed a small bias (-0.06%), with 95% limits of agreement of -1.19 and 1.79. Compared with healthy subjects, patients with hypertrophic CMP, dilated CMP, amyloidosis, and sarcoidosis had significantly higher myocardial ECV at dual

  10. Myocardial Extracellular Volume Fraction with Dual-Energy Equilibrium Contrast-enhanced Cardiac CT in Nonischemic Cardiomyopathy: A Prospective Comparison with Cardiac MR Imaging.

    PubMed

    Lee, Hye-Jeong; Im, Dong Jin; Youn, Jong-Chan; Chang, Suyon; Suh, Young Joo; Hong, Yoo Jin; Kim, Young Jin; Hur, Jin; Choi, Byoung Wook

    2016-07-01

    Purpose To evaluate the feasibility of equilibrium contrast material-enhanced dual-energy cardiac computed tomography (CT) to determine extracellular volume fraction (ECV) in nonischemic cardiomyopathy (CMP) compared with magnetic resonance (MR) imaging. Materials and Methods This study was approved by the institutional review board; informed consent was obtained. Seven healthy subjects and 23 patients (six with hypertrophic CMP, nine with dilated CMP, four with amyloidosis, and four with sarcoidosis) (mean age ± standard deviation, 57.33 years ± 14.82; 19 male participants [63.3%]) were prospectively enrolled. Twelve minutes after contrast material injection (1.8 mL/kg at 3 mL/sec), dual-energy cardiac CT was performed. ECV was measured by two observers independently. Hematocrit levels were compared between healthy subjects and patients with the Mann-Whitney U test. In per-subject analysis, interobserver agreement for CT was assessed with the intraclass correlation coefficient (ICC), and intertest agreement between MR imaging and CT was assessed with Bland-Altman analysis. In per-segment analysis, Student t tests in the linear mixed model were used to compare ECV on CT images between healthy subjects and patients. Results Hematocrit level was 43.44% ± 1.80 for healthy subjects and 41.23% ± 5.61 for patients with MR imaging (P = .16) and 43.50% ± 1.92 for healthy subjects and 41.35% ± 5.92 for patients with CT (P = .15). For observer 1 in per-subject analysis, ECV was 34.18% ± 8.98 for MR imaging and 34.48% ± 8.97 for CT. For observer 2, myocardial ECV was 34.42% ± 9.03 for MR imaging and 33.98% ± 9.05 for CT. Interobserver agreement for ECV at CT was excellent (ICC = 0.987). Bland-Altman analysis between MR imaging and CT showed a small bias (-0.06%), with 95% limits of agreement of -1.19 and 1.79. Compared with healthy subjects, patients with hypertrophic CMP, dilated CMP, amyloidosis, and sarcoidosis had significantly higher myocardial ECV at dual

  11. Effect of thermal annealing on the phase evolution of silver tungstate in Ag/WO₃ films.

    PubMed

    Bose, R Jolly; Sreedharan, R Sreeja; Krishnan, R Resmi; Reddy, V R; Gupta, Mukul; Ganesan, V; Sudheer, S K; Pillai, V P Mahadevan

    2015-06-15

    Silver/tungsten oxide multi-layer films are deposited over quartz substrates by RF magnetron sputtering technique and the films are annealed at temperatures 200, 400 and 600°C. The effect of thermal annealing on the phase evolution of silver tungstate phase in Ag/WO3 films is studied extensively using techniques like X-ray diffraction, micro-Raman analysis, atomic force microscopy and photoluminescence studies. The XRD pattern of the as-deposited film shows only the peaks of cubic phase of silver. The film annealed at 200°C shows the presence of XRD peaks corresponding to orthorhombic phase of Ag2WO4 and peaks corresponding to cubic phase of silver with reduced intensity. It is found that, as annealing temperature increases, the volume fraction of Ag decreases and that of Ag2WO4 phase increases and becomes highest at a temperature of 400°C. When the temperature increases beyond 400°C, the volume fraction of Ag2WO4 decreases, due to its decomposition into silver and oxygen deficient phase Ag2W4O13. The micro-Raman spectra of the annealed films show the characteristic bands of tungstate phase which is in agreement with XRD analysis. The surface morphology of the films studied by atomic force microscopy reveals that the particle size and r.m.s roughness are highest for the sample annealed at 400°C. In the photoluminescence study, the films with silver tungstate phase show an emission peak in blue region centered around the wavelength 441 nm (excitation wavelength 256 nm).

  12. Synthesis and Optical Responses of Ag@Au/Ag@Au Double Shells

    NASA Astrophysics Data System (ADS)

    Li, Ying-Ying; Liu, Xiao-Li; Yang, Da-Jie; Hao, Zhong-Hua; Wang, Qu-Quan

    2015-02-01

    We synthesize hollow-structured Ag@Au nanoparticles with single porous shell and Ag@Au/Ag@Au double shells by using the galvanic replacement reaction and investigate their linear and nonlinear optical properties. Our results show that the surface plasmon resonance wavelength of the hollow porous nanoparticles could be easily tuned in a wide range in the visible and near infrared region by controlling the volume of HAuCl4. The nonlinear optical refraction of the double-shelled Ag@Au/Ag@Au nanoparticles is prominently enhanced by the plasmon resonance. Our findings may find applications in biosensors and nonlinear optical nanodevices.

  13. A method to estimate the fractional fat volume within a ROI of a breast biopsy for WAXS applications: Animal tissue evaluation

    SciTech Connect

    Tang, Robert Y.; McDonald, Nancy Laamanen, Curtis; LeClair, Robert J.

    2014-11-01

    Purpose: To develop a method to estimate the mean fractional volume of fat (ν{sup ¯}{sub fat}) within a region of interest (ROI) of a tissue sample for wide-angle x-ray scatter (WAXS) applications. A scatter signal from the ROI was obtained and use of ν{sup ¯}{sub fat} in a WAXS fat subtraction model provided a way to estimate the differential linear scattering coefficient μ{sub s} of the remaining fatless tissue. Methods: The efficacy of the method was tested using animal tissue from a local butcher shop. Formalin fixed samples, 5 mm in diameter 4 mm thick, were prepared. The two main tissue types were fat and meat (fibrous). Pure as well as composite samples consisting of a mixture of the two tissue types were analyzed. For the latter samples, ν{sub fat} for the tissue columns of interest were extracted from corresponding pixels in CCD digital x-ray images using a calibration curve. The means ν{sup ¯}{sub fat} were then calculated for use in a WAXS fat subtraction model. For the WAXS measurements, the samples were interrogated with a 2.7 mm diameter 50 kV beam and the 6° scattered photons were detected with a CdTe detector subtending a solid angle of 7.75 × 10{sup −5} sr. Using the scatter spectrum, an estimate of the incident spectrum, and a scatter model, μ{sub s} was determined for the tissue in the ROI. For the composite samples, a WAXS fat subtraction model was used to estimate the μ{sub s} of the fibrous tissue in the ROI. This signal was compared to μ{sub s} of fibrous tissue obtained using a pure fibrous sample. Results: For chicken and beef composites, ν{sup ¯}{sub fat}=0.33±0.05 and 0.32 ± 0.05, respectively. The subtractions of these fat components from the WAXS composite signals provided estimates of μ{sub s} for chicken and beef fibrous tissue. The differences between the estimates and μ{sub s} of fibrous obtained with a pure sample were calculated as a function of the momentum transfer x. A t-test showed that the mean of the

  14. AGS 20th anniversary celebration

    SciTech Connect

    Baggett, N.V.

    1980-05-22

    On May 22, 1980, a symposium was held at Brookhaven to celebrate the 20th birthday of the AGS, to recall its beginnings, and to review major discoveries that have been made with its beams. The talks at the symposium are recorded in this volume.

  15. Optimization and evaluation of asymmetric flow field-flow fractionation of silver nanoparticles.

    PubMed

    Loeschner, Katrin; Navratilova, Jana; Legros, Samuel; Wagner, Stephan; Grombe, Ringo; Snell, James; von der Kammer, Frank; Larsen, Erik H

    2013-01-11

    Asymmetric flow field-flow fractionation (AF(4)) in combination with on-line optical detection and mass spectrometry is one of the most promising methods for separation and quantification of nanoparticles (NPs) in complex matrices including food. However, to obtain meaningful results regarding especially the NP size distribution a number of parameters influencing the separation need to be optimized. This paper describes the development of a separation method for polyvinylpyrrolidone-stabilized silver nanoparticles (AgNPs) in aqueous suspension. Carrier liquid composition, membrane material, cross flow rate and spacer height were shown to have a significant influence on the recoveries and retention times of the nanoparticles. Focus time and focus flow rate were optimized with regard to minimum elution of AgNPs in the void volume. The developed method was successfully tested for injected masses of AgNPs from 0.2 to 5.0 μg. The on-line combination of AF(4) with detection methods including ICP-MS, light absorbance and light scattering was helpful because each detector provided different types of information about the eluting NP fraction. Differences in the time-resolved appearance of the signals obtained by the three detection methods were explained based on the physical origin of the signal. Two different approaches for conversion of retention times of AgNPs to their corresponding sizes and size distributions were tested and compared, namely size calibration with polystyrene nanoparticles (PSNPs) and calculations of size based on AF(4) theory. Fraction collection followed by transmission electron microscopy was performed to confirm the obtained size distributions and to obtain further information regarding the AgNP shape. Characteristics of the absorbance spectra were used to confirm the presence of non-spherical AgNP. PMID:23261297

  16. Investigation of difficult component effects on finite element model vibration prediction for the Bell AG-1G helicopter. Volume 2: Correlation results

    NASA Technical Reports Server (NTRS)

    Dompka, R. V.

    1989-01-01

    Under the NASA-sponsored DAMVIBS (Design Analysis Methods for VIBrationS) program, a series of ground vibration tests and NASTRAN finite element model (FEM) correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Previous correlations of the AG-1G showed good agreement between NASTRAN and tests through 15 to 20 Hz, but poor agreement in the higher frequency range of 20 to 30 Hz. Thus, this effort emphasized the higher frequency airframe vibration response correlations and identified areas that need further R and T work. To conduct the investigations, selected difficult components (main rotor pylon, secondary structure, nonstructural doors/panels, landing gear, engine, furl, etc.) were systematically removed to quantify their effects on overall vibratory response of the airframe. The entire effort was planned and documented, and the results reviewed by NASA and industry experts in order to ensure scientific control of the testing, analysis, and correlation exercise. In particular, secondary structure and damping had significant effects on the frequency response of the airframe above 15 Hz. Also, the nonlinear effects of thrust stiffening and elastomer mounts were significant on the low frequency pylon modes below main rotor 1p (5.4 Hz). The results of the NASTRAN FEM correlations are given.

  17. Comparison of Echocardiographic and Cardiac Magnetic Resonance Imaging Measurements of Functional Single Ventricular Volumes, Mass, and Ejection Fraction (From the Pediatric Heart Network Multicenter Fontan Cross-Sectional Study)

    PubMed Central

    Margossian, Renee; Schwartz, Marcy L.; Prakash, Ashwin; Wruck, Lisa; Colan, Steven D.; Atz, Andrew M.; Bradley, Timothy J.; Fogel, Mark A.; Hurwitz, Lynne M.; Marcus, Edward; Powell, Andrew J.; Printz, Beth F.; Puchalski, Michael D.; Rychik, Jack; Shirali, Girish; Williams, Richard; Yoo, Shi-Joon; Geva, Tal

    2009-01-01

    Assessment of the size and function of the functional single ventricle (FSV) is a key element in the management of patients following the Fontan procedure. Measurement variability of ventricular mass, volume and ejection fraction between observers by echocardiography and CMR and their reproducibility between readers in these patients has not been described. From the 546 patients enrolled in the Pediatric Heart Network Fontan Cross-Sectional Study (mean age 11.9±3.4 years), 100 echocardiograms and 50 CMR studies were assessed for measurement reproducibility; 124 subjects with paired studies were selected for comparison between modalities. Inter-observer agreement for qualitative grading of ventricular function by echocardiography was modest for left ventricular (LV) morphology (kappa= 0.42) and weak for right ventricular (RV) morphology (kappa= 0.12). For quantitative assessment, high intra-class correlation coefficients (ICC) were found for echocardiographic inter-observer (LV= 0.87–0.92; RV= 0.82–0.85) agreement of systolic and diastolic volumes, respectively. In contrast, ICCs for LV and RV mass were moderate (LV= 0.78; RV= 0.72). The corresponding ICCs by CMR were high (LV= 0.96; RV= 0.85). Volumes by echocardiography averaged 70% of CMR values. Interobserver reproducibility of EF was similar for both modalities. Although the absolute mean difference between modalities for ejection fraction was small (<2%), 95% limits of agreement were wide. In conclusion, agreement between observers of qualitative FSV function by echocardiography is modest. Measurements of FSV volume by 2D echocardiography underestimate CMR measurements but their reproducibility is high. Echocardiographic and CMR measurements of FSV EF demonstrate similar interobserver reproducibility whereas measurements of FSV mass and LV diastolic volume are more reproducible by CMR. PMID:19616678

  18. 40 CFR 63.2854 - How do I determine the weighted average volume fraction of HAP in the actual solvent loss?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Hazardous Air Pollutants: Solvent Extraction for Vegetable Oil Production Compliance Requirements § 63.2854... fraction of HAP in extraction solvent received for use in your vegetable oil production process. By the end... recovered from off-site oil. To determine the HAP content of the material in each delivery of solvent,...

  19. 40 CFR 63.2854 - How do I determine the weighted average volume fraction of HAP in the actual solvent loss?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Hazardous Air Pollutants: Solvent Extraction for Vegetable Oil Production Compliance Requirements § 63.2854... fraction of HAP in extraction solvent received for use in your vegetable oil production process. By the end... recovered from off-site oil. To determine the HAP content of the material in each delivery of solvent,...

  20. AGS II

    SciTech Connect

    Palmer, R.B.

    1984-01-01

    Interest in rare K decays, neutrino oscillations and other fields have generated an increasing demand for running, and improved intensity and duty cycle, at the AGS. Current projects include acceleration of polarized protons and light ions (up to mass 32). Future plans are for a booster to increase intensity and allow heavy ions (up to mass 200), and a stretcher to give 100% duty cycle. A later upgrade could yield an average current of 32 ..mu.. amps. 6 figures, 2 tables.

  1. Changes of the transverse diameter and volume and dosimetry before the 25th fraction during the course of intensity-modulated radiation therapy (IMRT) for patients with nasopharyngeal carcinoma

    SciTech Connect

    Yang Haihua; Hu Wei; Ding Weijun; Shan Guoping; Wang Wei; Yu Changhui; Wang Biyun; Shao Minghai; Wang Jianhua; Yang Weifang

    2012-07-01

    To quantify changes of the transverse diameter and volume and dosimetry, and to illustrate the inferiority of non-replanning during intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) patients. Fifty-three NPC patients who received IMRT in 33 fractions were enrolled in this prospective trial. Before the 25th fraction, a new simulation computed tomography (CT) scan was acquired for all patients. The dose-volume histograms of the phantom plan were compared with the initial plan. Significant reduction of the transverse diameter of the nasopharyngeal, the neck, and 2 parotid glands volume was observed on second CT compared with the first CT (mean reduction 7.48 {+-} 4.45 mm, 6.80 {+-} 15.14 mm, 5.70 {+-} 6.26 mL, and 5.04 {+-} 5.85 mL, respectively; p < 0.01). The maximum dose and V-40 of the spinal cord, mean dose, and V30 of the left and right parotid, and V-50 of the brain stem were increased significantly in the phantom plan compared with the initial plan (mean increase 4.75 {+-} 5.55 Gy, 7.18 {+-} 10.07%, 4.51 {+-} 8.55 Gy, 6.59 {+-} 17.82%, 5.33 {+-} 8.55 Gy, 11.68 {+-} 17.11% and 1.48 {+-} 3.67%, respectively; p < 0.01). On the basis of dose constraint criterion in the RTOG0225 protocol, the dose of the normal critical structures for 52.83% (28/53) of the phantom plans were out of limit compared with 1.89% (1/53) of the initial plans (p < 0.0001). Because of the significant change in anatomy and dose before the 25th fraction during IMRT, replanning should be necessary during IMRT with NPC.

  2. Fractional randomness

    NASA Astrophysics Data System (ADS)

    Tapiero, Charles S.; Vallois, Pierre

    2016-11-01

    The premise of this paper is that a fractional probability distribution is based on fractional operators and the fractional (Hurst) index used that alters the classical setting of random variables. For example, a random variable defined by its density function might not have a fractional density function defined in its conventional sense. Practically, it implies that a distribution's granularity defined by a fractional kernel may have properties that differ due to the fractional index used and the fractional calculus applied to define it. The purpose of this paper is to consider an application of fractional calculus to define the fractional density function of a random variable. In addition, we provide and prove a number of results, defining the functional forms of these distributions as well as their existence. In particular, we define fractional probability distributions for increasing and decreasing functions that are right continuous. Examples are used to motivate the usefulness of a statistical approach to fractional calculus and its application to economic and financial problems. In conclusion, this paper is a preliminary attempt to construct statistical fractional models. Due to the breadth and the extent of such problems, this paper may be considered as an initial attempt to do so.

  3. Exposure-dependent Ag+ release from silver nanoparticles and its complexation in AgS2 sites in primary murine macrophages

    NASA Astrophysics Data System (ADS)

    Veronesi, G.; Aude-Garcia, C.; Kieffer, I.; Gallon, T.; Delangle, P.; Herlin-Boime, N.; Rabilloud, T.; Carrière, M.

    2015-04-01

    Silver nanoparticle (AgNP) toxicity is related to their dissolution in biological environments and to the binding of the released Ag+ ions in cellulo; the chemical environment of recombined Ag+ ions is responsible for their toxicological outcome, moreover it is indicative of the cellular response to AgNP exposure, and can therefore shed light on the mechanisms governing AgNP toxicity. This study probes the chemistry of Ag species in primary murine macrophages exposed to AgNPs by making use of X-ray Absorption Fine Structure spectroscopy under cryogenic conditions: the linear combination analysis of the near-edge region of the spectra provides the fraction of Ag+ ions released from the AgNPs under a given exposure condition and highlights their complexation with thiolate groups; the ab initio modelling of the extended spectra allows measuring the Ag-S bond length in cellulo. Dissolution rates depend on the exposure scenario, chronicity leading to higher Ag+ release than acute exposure; Ag-S bond lengths are 2.41 +/- 0.03 Å and 2.38 +/- 0.01 Å in acute and chronic exposure respectively, compatible with digonal AgS2 coordination. Glutathione is identified as the most likely putative ligand for Ag+. The proposed method offers a scope for the investigation of metallic nanoparticle dissolution and recombination in cellular models.Silver nanoparticle (AgNP) toxicity is related to their dissolution in biological environments and to the binding of the released Ag+ ions in cellulo; the chemical environment of recombined Ag+ ions is responsible for their toxicological outcome, moreover it is indicative of the cellular response to AgNP exposure, and can therefore shed light on the mechanisms governing AgNP toxicity. This study probes the chemistry of Ag species in primary murine macrophages exposed to AgNPs by making use of X-ray Absorption Fine Structure spectroscopy under cryogenic conditions: the linear combination analysis of the near-edge region of the spectra provides

  4. Functional analysis of the α-1,3-glucan synthase genes agsA and agsB in Aspergillus nidulans: agsB is the major α-1,3-glucan synthase in this fungus.

    PubMed

    Yoshimi, Akira; Sano, Motoaki; Inaba, Azusa; Kokubun, Yuko; Fujioka, Tomonori; Mizutani, Osamu; Hagiwara, Daisuke; Fujikawa, Takashi; Nishimura, Marie; Yano, Shigekazu; Kasahara, Shin; Shimizu, Kiminori; Yamaguchi, Masashi; Kawakami, Kazuyoshi; Abe, Keietsu

    2013-01-01

    Although α-1,3-glucan is one of the major cell wall polysaccharides in filamentous fungi, the physiological roles of α-1,3-glucan remain unclear. The model fungus Aspergillus nidulans possesses two α-1,3-glucan synthase (AGS) genes, agsA and agsB. For functional analysis of these genes, we constructed several mutant strains in A. nidulans: agsA disruption, agsB disruption, and double-disruption strains. We also constructed several CagsB strains in which agsB expression was controlled by the inducible alcA promoter, with or without the agsA-disrupting mutation. The agsA disruption strains did not show markedly different phenotypes from those of the wild-type strain. The agsB disruption strains formed dispersed hyphal cells under liquid culture conditions, regardless of the agsA genetic background. Dispersed hyphal cells were also observed in liquid culture of the CagsB strains when agsB expression was repressed, whereas these strains grew normally in plate culture even under the agsB-repressed conditions. Fractionation of the cell wall based on the alkali solubility of its components, quantification of sugars, and (13)C-NMR spectroscopic analysis revealed that α-1,3-glucan was the main component of the alkali-soluble fraction in the wild-type and agsA disruption strains, but almost no α-1,3-glucan was found in the alkali-soluble fraction derived from either the agsB disruption strain or the CagsB strain under the agsB-repressed conditions, regardless of the agsA genetic background. Taken together, our data demonstrate that the two AGS genes are dispensable in A. nidulans, but that AgsB is required for normal growth characteristics under liquid culture conditions and is the major AGS in this species.

  5. A study of the microstructure, thermal properties and wetting kinetics of Sn-3Ag- xZn lead-free solders

    NASA Astrophysics Data System (ADS)

    Li, Yulong; Yu, Xiao; Sekulic, Dusan P.; Hu, Xiaowu; Yan, Ming; Hu, Ronghua

    2016-06-01

    Microstructure, thermal properties and wetting kinetics of Sn-3Ag- xZn solders ( x = 0.4, 0.6, 0.8, 1, 2 and 4 wt%) were systematically investigated. The results indicate that a small amount of Zn (Zn wt% ≤ 1 wt%) has a rather moderate effect on the microstructure morphology of the Sn-3Ag- xZn solders. The microstructures are composed of a β-Sn phase and the mixture of Ag3Sn and ζ-AgZn particles. However, the β-Sn phase reduces its volume fraction in the entire microstructure and the intermetallic compounds population increases with the increasing of Zn content. The microstructure is dramatically changed with a further increase in the Zn content. The γ-AgZn phase is formed in a Sn-3Ag-2Zn solder. The ɛ-AgZn phase is formed in a Sn-3Ag-4Zn solder. The melting temperature and the undercooling of the Sn-3Ag- xZn solder alloys decrease with the increase in Zn content, reach to a minimum value when the content of Zn is 1 wt%, and then increase with further increase in Zn content. The Sn-3Ag-1Zn demonstrates the minimum value of 228.13 °C in the melting temperature and 13.87 °C in undercooling. The wetting kinetics of the main spreading stage features the power law of R n ~ t ( n = 1), which is controlled by chemical reactions at the triple line.

  6. Development of the FMT chemical transport simulator: Advective transport sensitivity to aqueous density and mineral volume fraction coupled to phase compositions

    SciTech Connect

    Novak, C.F.

    1993-12-31

    The Fracture-Matrix Transport (FMT) code couples saturated porous media advection and diffusion with mechanistic chemical models for speciation and interphase reactions. FMT is being developed to support actinide solubility and retardation studies for the Waste Isolation Pilot Plant (WIPP), USDOE facility for demonstrating safe disposal of transuranic waste. Hydrologic studies of water-bearing units above the WIPP indicate double-porosity transport behavior in some locations, with groundwater concentrations ranging which potable to highly concentrated. Previously, FMT simulated such systems in two-dimensions on the continuum from advection- to diffusion-dominated, with a user-specified velocity field that allows double-porosity transport. However, aqueous density was assumed constant, and reactive minerals were assumed to occupy negligible volume. Both of these assumptions can be considered poor for evaporite systems, where large changes in porosity and aqueous density can result from high mineral solubilities. Therefore, further development of FMT has relaxed these restrictions, allowing aqueous density to vary with phase composition, and allowing void volume to change as minerals dissolve and precipitate. This paper describes the additional mathematical complexity required to simulate such systems. The sensitivity of advection-dominated transport to these variables is explored through an extended example.

  7. Finite-volume energy spectrum, fractionalized strings, and low-energy effective field theory for the quantum dimer model on the square lattice

    NASA Astrophysics Data System (ADS)

    Banerjee, D.; Bögli, M.; Hofmann, C. P.; Jiang, F.-J.; Widmer, P.; Wiese, U.-J.

    2016-09-01

    We present detailed analytic calculations of finite-volume energy spectra, mean-field theory, as well as a systematic low-energy effective field theory for the square lattice quantum dimer model. An emergent approximate spontaneously broken SO(2 ) symmetry gives rise to a pseudo-Goldstone boson. Remarkably, this soft phononlike excitation, which is massless at the Rokhsar-Kivelson (RK) point, exists far beyond this point. The Goldstone physics is captured by a systematic low-energy effective field theory. We determine its low-energy parameters by matching the analytic effective field theory with exact diagonalization results. This confirms that the model exists in the columnar (and not in a plaquette or mixed) phase all the way to the RK point.

  8. A Coupled Mean Field / Gurson-Tvergaard Micromechanical Model For Ductile Fracture In Multiphase Materials With Large Volume Fraction of Voids

    NASA Astrophysics Data System (ADS)

    Van Hoof, Thibaut; Piérard, Olivier; Lani, Frédéric

    2007-04-01

    In the framework of the European project PROHIPP (New design and manufacturing processes for high pressure fluid power product — NMP 2-CT-2004-50546), CENAERO develops a library of constitutive models used to predict the mechanical response of a family of cast iron. The present contribution focuses on one particular microstructure, corresponding to a ferrite matrix containing spheroidal graphite and isolated inclusions of pearlite. An incremental mean field homogenisation scheme such as the one developed by Doghri and Ouaar is used. In the present application, the ferrite matrix is described by a Gurson type constitutive law (porous plasticity) while the pearlite inclusions are assumed to obey the classical isotropic J2 plasticity. The predictions of the micromechanical model are compared to the results of Finite Element simulations performed on three-dimensional representative volume elements (RVEs).

  9. Preparation, characterization, and photocatalytic activity of porous AgBr@Ag and AgBrI@Ag plasmonic photocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Tian, Baozhu; Zhang, Jinlong; Xiong, Tianqing; Wang, Tingting

    2014-02-01

    Porous AgBr@Ag and AgBrI@Ag plasmonic photocatalysts were synthesized by a multistep route, including a dealloying method to prepare porous Ag, a transformation from Ag to AgBr and AgBrI, and a photo-reduction process to form Ag nanoparticles on the surface of AgBr and AgBrI. It was found that the porous structure kept unchanged during Ag was transferred into AgBr, AgBrI, AgBr@Ag, and AgBrI@Ag. Both porous AgBr@Ag and porous AgBrI@Ag showed much higher visible-light photocatalytic activity than cubic AgBr@Ag for the degradation of methyl orange, which is because the interconnected pore channels not only provide more reactive sites but also favor the transportation of photo-generated electrons and holes. For AgBrI@Ag, AgBrI solid solution formed at the interface of AgBr and AgI, and the phase junction can effectively separate the photo-generated electrons and holes, favorable to the improvement of photocatalytic activity. The optimal I content for obtaining the highest activity is ∼10 at.%.

  10. High Dose-Per-Fraction Irradiation of Limited Lung Volumes Using an Image-Guided, Highly Focused Irradiator: Simulating Stereotactic Body Radiotherapy Regimens in a Small-Animal Model

    SciTech Connect

    Cho, Jaeho; Kodym, Reinhard; Seliounine, Serguei

    2010-07-01

    Purpose: To investigate the underlying biology associated with stereotactic body radiotherapy (SBRT), both in vivo models and image-guided, highly focal irradiation systems are necessary. Here, we describe such an irradiation system and use it to examine normal tissue toxicity in a small-animal model at lung volumes similar to those associated with human therapy. Methods and Materials: High-dose radiation was delivered to a small volume of the left lung of C3H/HeJCr mice using a small-animal stereotactic irradiator. The irradiator has a collimation mechanism to produce focal radiation beams, an imaging subsystem consisting of a fluorescent screen coupled to a charge-coupled device camera, and a manual positioning stage. Histopathologic examination and micro-CT were used to evaluate the radiation response. Results: Focal obliteration of the alveoli by fibrous connective tissue, hyperplasia of the bronchiolar epithelium, and presence of a small number of inflammatory cells are the main reactions to low-volume/high-dose irradiation of the mouse lung. The tissue response suggested a radiation dose threshold for early phase fibrosis lying between 40 and 100 Gy. The irradiation system satisfied our requirements of high-dose-rate, small beam diameter, and precise localization and verification. Conclusions: We have established an experimental model and image-guided animal irradiation system for the study of high dose per fraction irradiations such as those used with SBRT at volumes analogous to those used in human beings. It will also allow the targeting of specific anatomical structures of the thorax or ultimately, orthotopic tumors of the lung.

  11. Comparison of Multi-Echo Dixon Methods with Volume Interpolated Breath-Hold Gradient Echo Magnetic Resonance Imaging in Fat-Signal Fraction Quantification of Paravertebral Muscle

    PubMed Central

    Yoo, Yeon Hwa; Kim, Hak-Sun; Lee, Young Han; Yoon, Choon-Sik; Paek, Mun Young; Yoo, Hanna; Kannengiesser, Stephan; Chung, Tae-Sub; Song, Ho-Taek; Suh, Jin-Suck

    2015-01-01

    Objective To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2* estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2*-corrected two-echo Dixon or T2*-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. Materials and Methods Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2*-corrected Dixon technique with two (non-T2*-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. Results A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. Conclusion T2*-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification. PMID:26357503

  12. Stereotactic Body Radiotherapy for Primary Lung Cancer at a Dose of 50 Gy Total in Five Fractions to the Periphery of the Planning Target Volume Calculated Using a Superposition Algorithm

    SciTech Connect

    Takeda, Atsuya; Sanuki, Naoko; Kunieda, Etsuo Ohashi, Toshio; Oku, Yohei; Takeda, Toshiaki; Shigematsu, Naoyuki; Kubo, Atsushi

    2009-02-01

    Purpose: To retrospectively analyze the clinical outcomes of stereotactic body radiotherapy (SBRT) for patients with Stages 1A and 1B non-small-cell lung cancer. Methods and Materials: We reviewed the records of patients with non-small-cell lung cancer treated with curative intent between Dec 2001 and May 2007. All patients had histopathologically or cytologically confirmed disease, increased levels of tumor markers, and/or positive findings on fluorodeoxyglucose positron emission tomography. Staging studies identified their disease as Stage 1A or 1B. Performance status was 2 or less according to World Health Organization guidelines in all cases. The prescribed dose of 50 Gy total in five fractions, calculated by using a superposition algorithm, was defined for the periphery of the planning target volume. Results: One hundred twenty-one patients underwent SBRT during the study period, and 63 were eligible for this analysis. Thirty-eight patients had Stage 1A (T1N0M0) and 25 had Stage 1B (T2N0M0). Forty-nine patients were not appropriate candidates for surgery because of chronic pulmonary disease. Median follow-up of these 49 patients was 31 months (range, 10-72 months). The 3-year local control, disease-free, and overall survival rates in patients with Stages 1A and 1B were 93% and 96% (p = 0.86), 76% and 77% (p = 0.83), and 90% and 63% (p = 0.09), respectively. No acute toxicity was observed. Grade 2 or higher radiation pneumonitis was experienced by 3 patients, and 1 of them had fatal bacterial pneumonia. Conclusions: The SBRT at 50 Gy total in five fractions to the periphery of the planning target volume calculated by using a superposition algorithm is feasible. High local control rates were achieved for both T2 and T1 tumors.

  13. Impact of Epoetin Alfa on LV Structure, Function, and Pressure-Volume Relations as Assessed by Cardiac Magnetic Resonance – The Heart Failure Preserved Ejection Fraction (HFPEF) Anemia Trial

    PubMed Central

    Green, Philip; Babu, Benson A.; Teruya, Sergio; Helmke, Stephen; Prince, Martin; Maurer, Mathew S.

    2013-01-01

    Background Anemia, a common co-morbidity in older adults with heart failure and a preserved ejection fraction (HFPEF), is associated with worse outcomes. We quantified the effect of anemia treatment on left ventricular (LV) structure and function as measured by cardiac magnetic resonance (CMR) imaging. Methods Prospective, randomized single blind clinical trial (NCT NCT00286182) comparing the safety and efficacy of epoetin alfa versus placebo for 24 weeks in which a sub-group (n=22) had cardiac MRI at baseline and after 3 and 6 months to evaluate changes in cardiac structure and function. Pressure volume (PV) indices were derived from MRI measures of ventricular volume coupled with sphygmomanometer-measured pressure and Doppler estimates of filling pressure. The end-systolic and end-diastolic PV relations and the area between them as a function of end-diastolic pressure, the isovolumic PV area (PVAiso), were calculated Results Subjects (75±10 years, 64% female) with HFPEF (EF=63±15%) with average hemoglobin of 10.3±1.1 gm/dl were treated with epoetin alfa using a dose adjusted algorithm that increased hemoglobin compared to placebo (p<0.0001). As compared to baseline, there were no significant changes in end diastolic (−7±8 vs. −3±8 ml, p=0.81) or end systolic (−0.4±2 vs. −0.7±5 ml, p= 0.96) volumes at 6 month follow-up between epoetin alfa compared with placebo. LV function as measured based on EF (−1.5±1.6% vs.−2.6±3.3%, p= 0.91) and pressure volume indices (PVa-iso-EDP at 30 mm Hg, −5071±4308 vs. −1662±4140 p=0.58) did not differ between epoetin alfa and placebo. Conclusion Administration of epoetin alfa to older adult patients with HFPEF resulted in a significant increase in hemoglobin, without evident change in LV structure, function, or pressure volume relationships as measured quantitatively using CMR. PMID:23517485

  14. Feasibility study of stereotactic body radiotherapy for peripheral lung tumors with a maximum dose of 100 Gy in five fractions and a heterogeneous dose distribution in the planning target volume.

    PubMed

    Takeda, Atsuya; Oku, Yohei; Sanuki, Naoko; Eriguchi, Takahisa; Aoki, Yousuke; Enomoto, Tatsuji; Kaneko, Takeshi; Nishimura, Shuichi; Kunieda, Etsuo

    2014-09-01

    We evaluated toxicity and outcomes for patients with peripheral lung tumors treated with stereotactic body radiation therapy (SBRT) in a dose-escalation and dose-convergence study. A total of 15 patients were enrolled. SBRT was performed with 60 Gy in 5 fractions (fr.) prescribed to the 60% isodose line of maximum dose, which was 100 Gy in 5 fr., covering the planning target volume (PTV) surface (60 Gy/5 fr. - (60%-isodose)) using dynamic conformal multiple arc therapy (DCMAT). The primary endpoint was radiation pneumonitis (RP) ≥ Grade 2 within 6 months. Toxicities were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. Using dose-volumetric analysis, the trial regimen of 60 Gy/5 fr. - (60%-isodose) was compared with our institutional conventional regimen of 50 Gy/5 fr. - (80%-isodose). The enrolled consecutive patients had either a solitary peripheral tumor or two ipsilateral tumors. The median follow-up duration was 22.0 (12.0-27.0) months. After 6 months post-SBRT, the respective number of RP Grade 0, 1 and 2 cases was 5, 9 and 1. In the Grade 2 RP patient, the image showed an organizing pneumonia pattern at 6.0 months post-SBRT. No other toxicity was found. At last follow-up, there was no evidence of recurrence of the treated tumors. The target volumes of 60 Gy/ 5 fr. - (60%-isodose) were irradiated with a significantly higher dose than those of 50 Gy/5 fr. - (80%-isodose), while the former dosimetric parameters of normal lung were almost equivalent to the latter. SBRT with 60 Gy/5 fr. - (60%-isodose) using DCMAT allowed the delivery of very high and convergent doses to peripheral lung tumors with feasibility in the acute and subacute phases. Further follow-up is required to assess for late toxicity.

  15. Fraction Reduction through Continued Fractions

    ERIC Educational Resources Information Center

    Carley, Holly

    2011-01-01

    This article presents a method of reducing fractions without factoring. The ideas presented may be useful as a project for motivated students in an undergraduate number theory course. The discussion is related to the Euclidean Algorithm and its variations may lead to projects or early examples involving efficiency of an algorithm.

  16. Transport of silver nanoparticles (AgNPs) in soil.

    PubMed

    Sagee, Omer; Dror, Ishai; Berkowitz, Brian

    2012-07-01

    The effect of soil properties on the transport of silver nanoparticles (AgNPs) was studied in a set of laboratory column experiments, using different combinations of size fractions of a Mediterranean sandy clay soil. The AgNPs with average size of ~30nm yielded a stable suspension in water with zeta potential of -39mV. Early breakthrough of AgNPs in soil was observed in column transport experiments. AgNPs were found to have high mobility in soil with outlet relative concentrations ranging from 30% to 70%, depending on experimental conditions. AgNP mobility through the column decreased when the fraction of smaller soil aggregates was larger. The early breakthrough pattern was not observed for AgNPs in pure quartz columns nor for bromide tracer in soil columns, suggesting that early breakthrough is related to the nature of AgNP transport in natural soils. Micro-CT and image analysis used to investigate structural features of the soil, suggest that soil aggregate size strongly affects AgNP transport in natural soil. The retention of AgNPs in the soil column was reduced when humic acid was added to the leaching solution, while a lower flow rate (Darcy velocity of 0.17cm/min versus 0.66cm/min) resulted in higher retention of AgNPs in the soil. When soil residual chloride was exchanged by nitrate prior to column experiments, significantly improved mobility of AgNPs was observed in the soil column. These findings point to the importance of AgNP-soil chemical interactions as a retention mechanism, and demonstrate the need to employ natural soils rather than glass beads or quartz in representative experimental investigations.

  17. AGS experiments - 1994, 1995, 1996

    SciTech Connect

    Depken, J.C.

    1997-01-01

    This report contains the following information on the Brookhaven AGS Accelerator complex: FY 1996 AGS schedule as run; FY 1997 AGS schedule (working copy); AGS beams 1997; AGS experimental area FY 1994 physics program; AGS experimental area FY 1995 physics program; AGS experimental area FY 1996 physics program; AGS experimental area FY 1997 physics program (in progress); a listing of experiments by number; two-phage summaries of each experiment begin here, also ordered by number; listing of publications of AGS experiments begins here; and listing of AGS experimenters begins here.

  18. Measurement and Modeling of Resistivity as a Microscale Tool to Quantify the Volume Fraction of Lenticular (alpha)' Particles in a Partially Transformed (delta)-phase Pu-Ga Matrix

    SciTech Connect

    Haslam, J J; Wall, M A; Johnson, D L; Mayhall, D J; Schwartz, A J

    2005-07-13

    We have measured and modeled the change in electrical resistivity due to partial transformation to the martensitic {alpha}{prime}-phase in a {delta}-phase Pu-Ga matrix. The primary objective is to relate the change in resistance, measured with a 4-probe technique during the transformation, to the volume fraction of the {alpha}{prime} phase created in the microstructure. Analysis by finite element methods suggests that considerable differences in the resistivity may be anticipated depending on the orientational and morphological configurations of the {alpha}{prime} particles. Finite element analysis of the computed resistance of an assembly of lenticular shaped particles indicates that series resistor or parallel resistor approximations are inaccurate and can lead to an underestimation of the predicted amount of {alpha}{prime} in the sample by 15% or more. Comparison of the resistivity of a simulated network of partially transformed grains or portions of grains suggests that a correction to the measured resistivity allows quantification of the amount of {alpha}{prime} phase in the microstructure with minimal consideration of how the {alpha}{prime} morphology may evolve. It is found that the average of the series and parallel resistor approximations provide the most accurate relationship between the measured resistivity and the amount of {alpha}{prime} phase. The methods described here are applicable to any evolving two-phase microstructure in which the resistance difference between the two phases is measurable.

  19. Electromigration Behaviors of Cu Reinforced Sn-3.5Ag Composite Solder Joints

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Han, Jing; Ma, Limin; Zuo, Yong; Guo, Fu

    2016-09-01

    The composite approach, by incorporating small amounts of reinforcement particles in the solder matrix, has proven to be one of the effective ways to improve the reliability of solder joints. The effects of Cu addition on electromigration were investigated in this study by incorporating 2% volume fraction Cu particles into Sn-3.5Ag eutectic solder paste by the in situ process. The one-dimensional solder joints, designed to prevent the current crowding effect, were stressed under a constant current density of 104 A/cm2 at room temperature, and the temperature of the sample could reach 105 ± 5°C due to the Joule heating effect. Doping 2 vol.% Cu was found to retard the electromigration phenomenon effectively. After electric current stressing for 528 h, the growth rate of an interfacial intermetallic compound (IMC) layer at the anode decreased 73% in contrast to that of Sn-3.5Ag solder joints, and the IMC layer at the cathode was almost unchanged. The polarization effect of Cu reinforced composite solder joints was also apparently mitigated. In addition, the surface damage of the composite solder joints was relieved by incorporating 2 vol.% Cu particles. Compared to Sn-3.5Ag solder joints, which had protruded Cu6Sn5 and wrinkles of Sn-solder matrix on the surface, the solder joints with Cu addition had a more even surface.

  20. Release Fraction Evaluation

    SciTech Connect

    Bamberger, Judith A.; Glissmeyer, John A.

    2004-01-01

    This document presents results of experiments conducted to measure release fractions during certain tank retrieval processes. The tests were performed in a 1/4 scale model of a waste storage tank. The retrieval processes simulated were: (1) Discharging liquid or slurry from the mouth of a vertically oriented two-in. Schedule 40 pipe. The discharging material was in free-fall from the mouth of the pipe near the top of the tank into a liquid or slurry pool at the bottom of the tank. (2) The jet from a 9/16-in.-diameter nozzle transferring liquid or slurry waste from one side of the tank to the other. The discharging liquid was aimed at the opposite side of the tank from the nozzle and either impacted the tank wall or fell into a liquid or slurry pool in the bottom of the tank. (3) A high pressure fan jet of liquid striking a steel plate or simulated waste from a stand-off distance of a few inches. For each process, a water-soluble fluorescent dye was added to the liquid fraction as a tracer. Kaolin clay was used to represent the solids. The tank was covered and there was no forced ventilation in the tank during the tests. Six air samples were collected during each test. The air samples were collected at fixed positions in the tank. The air sample filters were dried and weighed to determine the solids collection. The fluorescent dye was then leached from each filter and quantified with a fluorometer to determine the collection of liquid. Samples of the slurry and liquid simulants were also collected to determine the quantities of simulant used in each test. To calculate the release fraction, the quantity collected on each air sample was adjusted for the fraction of the tank volume sampled and divided by the quantity of material exposed in the simulation. The method was not as sensitive for the solids content as it was for the liquid content, but in those instances where a solids release fraction was determined, it was in relatively good agreement with that of the

  1. The Structure and Electrical Properties of the Ag2Se + Ga2Se3 + GeSe2 Glass System

    NASA Astrophysics Data System (ADS)

    Marple, Maxwell Adam Thomas

    Silver containing homogeneous chalcogenide glasses in the ternary system Ag2Se-Ga2Se3-GeSe2 (AGGS) are synthesized and their atomic structure-property relationships are investigated. Structural studies are carried out using Raman, 77Se, 71Ga, 69Ga, and 109Ag nuclear magnetic resonance (NMR) spectroscopy. The structure of these glasses consists primarily of a network of corner sharing (Ga/Ge)Se4/2 tetrahedra with a small fraction of homopolar Se-Se bonds. Compositional modification of the atomic structure follows the charge compensated network model developed in the literature for aluminosilicate glasses. Ag2Se acts as a network modifier, forming non-bridging Se in glasses with Ag/Ga >1, while Ga 2Se3 plays the role of a network intermediate similar to Al2O3 in oxide glasses. The network favors the formation of homopolar Ge-Ge bonding in glasses with Ag/Ga <1, to accommodate the Se deficiency brought by the incorporation of Ga2Se3 with Ga being tetrahedrally coordinated to Se. This structural model is consistent with the variation in the glass transition temperatures and molar volume. Electrical Impedance Spectroscopy (EIS) reveals the ionic conductivity of the AGGS glasses to be quite high at ambient temperature, reaching up to 10 --4 S/cm for glasses with the highest Ag content. Increasing Se deficiency with respect to stoichiometry can enhance the conductivity further to ˜3x10--4 S/cm . Transference number measurements using the electromotive force (EMF) method as well as variable temperature 109Ag NMR line shape studies indicate that the conductivity is predominantly ionic in nature and results from fast hopping dynamics of Ag ions. The high ionic conductivity can be related to a heavily modified structural network that results in a potential energy landscape with many suitable hopping sites for the Ag ions. These structural characteristics and electrical properties of the glasses in the AGGS system may guide in the development of next generation fast ion

  2. AgRISTARS

    NASA Technical Reports Server (NTRS)

    1984-01-01

    An introduction to the overall AgRISTARS program, a general statement on progress, and separate summaries of the activities of each project, with emphasis on the technical highlights are presented. Organizational and management information on AgRISTARS is included in the appendices, as is a complete bibliography of publication and reports.

  3. AGS experiments: 1993 - 1994 - 1995

    SciTech Connect

    Depken, J.C.

    1996-04-01

    This report contains: FY 1995 AGS Schedule as Run; FY 1996-97 AGE Schedule (working copy); AGS Beams 1995; AGS Experimental Area FY 1993 Physics Program; AGS Experimental Area FY 1994 Physics Program; AGS Experimental Area FY 1995 Physics Program; AGS Experimental Area FY 1996 Physics Program (In progress); A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Listing of publications of AGS experiments begins here; and Listing of AGS experimenters begins here. This is the twelfth edition.

  4. Rapidly solidified Ag-Cu eutectics: A comparative study using drop-tube and melt fluxing techniques

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Mullis, A. M.; Cochrane, R. F.

    2016-03-01

    A comparative study of rapid solidification of Ag-Cu eutectic alloy processed via melt fluxing and drop-tube techniques is presented. A computational model is used to estimate the cooling rate and undercooling of the free fall droplets as this cannot be determined directly. SEM micrographs show that both materials consist of lamellar and anomalous eutectic structures. However, below the critical undercooling the morphologies of each are different in respect of the distribution and volume of anomalous eutectic. The anomalous eutectic in flux- undercooled samples preferentially forms at cell boundaries around the lamellar eutectic in the cell body. In drop-tube processed samples it tends to distribute randomly inside the droplets and at much smaller volume fractions. That the formation of the anomalous eutectic can, at least in part, be suppressed in the drop-tube is strongly suggestive that the formation of anomalous eutectic occurs via remelting process, which is suppressed by rapid cooling during solidification.

  5. A Convenient Method for Comparison of Efficiency of Fractionating Columns.

    ERIC Educational Resources Information Center

    Higgins, Robert H.

    1990-01-01

    Presented is a method for demonstrating the use of various fractionating columns to resolve mixtures into individual components and to correlate the resolving powers of column packings to their "hold-up" volumes. Fractions were analyzed using refractive indices. (KR)

  6. Transport of engineered silver (Ag) nanoparticles through partially fractured sandstones.

    PubMed

    Neukum, Christoph; Braun, Anika; Azzam, Rafig

    2014-08-01

    Transport behavior and fate of engineered silver nanoparticles (AgNP) in the subsurface is of major interest concerning soil and groundwater protection in order to avoid groundwater contamination of vital resources. Sandstone aquifers are important groundwater resources which are frequently used for public water supply in many regions of the world. The objective of this study is to get a better understanding of AgNP transport behavior in partially fractured sandstones. We executed AgNP transport studies on partially fissured sandstone drilling cores in laboratory experiments. The AgNP concentration and AgNP size in the effluent were analyzed using flow field-flow fractionation mainly. We employed inverse mathematical models on the measured AgNP breakthrough curves to identify and quantify relevant transport processes. Physicochemical filtration, time-dependent blocking due to filling of favorable attachment sites and colloid-facilitated transport were identified as the major processes for AgNP mobility. Physicochemical filtration was found to depend on solute chemistry, mineralogy, pore size distribution and probably on physical and chemical heterogeneity. Compared to AgNP transport in undisturbed sandstone matrix reported in the literature, their mobility in partially fissured sandstone is enhanced probably due to larger void spaces and higher hydraulic conductivity.

  7. Ramification of variable thickness on MHD TiO2 and Ag nanofluid flow over a slendering stretching sheet using NDM

    NASA Astrophysics Data System (ADS)

    Acharya, Nilankush; Das, Kalidas; Kumar Kundu, Prabir

    2016-09-01

    The present investigation reveals the effect of variable thickness on the steady two-dimensional boundary layer flows of a TiO2-water and Ag-water nanofluid through a slendering stretching sheet. The whole analysis has been performed in the presence of variable magnetic field and variable surface temperature. Similarity transformation has been introduced to renovate the non-linear partial differential equations into ordinary ones and then they were solved using the innovative technique of Natural decomposition method (NDM). The influence of pertinent parameters on velocity and temperature distribution has been illustrated by means of graphs and tables approach. Our analysis conveys that the temperature of the nanofluid reduces due to enhancing of the variable thickness parameter. The rate of heat transfer is significantly reduced for the Ag-water nanofluid with the positive impact of nanoparticle volume fraction.

  8. Atomic oxygen flux determined by mixed-phase Ag/Ag2O deposition

    SciTech Connect

    Kaspar, Tiffany C.; Droubay, Timothy C.; Chambers, Scott A.

    2010-11-01

    The flux of atomic oxygen generated in a electron cyclotron resonance (ECR) microwave plasma source was quantified by two different methods. The commonly applied approach of monitoring the frequency change of a silver-coated quartz crystal microbalance (QCM) deposition rate monitor as the silver is oxidized was found to underestimate the atomic oxygen flux by an order of magnitude compared to a more direct deposition approach. In the mixed-phase Ag/Ag2O deposition method, silver films were deposited in the presence of the plasma such that the films were partially oxidized to Ag2O; x-ray photoelectron spectroscopy (XPS) was utilized for quantification of the oxidized fraction. The inaccuracy of the QCM oxidation method was tentatively attributed to efficient catalytic recombination of O atoms on the silver surface.

  9. Optical Property Trends in Metal/Polymer (Ag/PVDF) Nanocomposites: A Computational Study

    NASA Astrophysics Data System (ADS)

    Rowan, Christopher Kenneth

    Metal-polymer nanocomposite materials were found to have highly tunable optical properties. Density functional theory-based calculations were employed to study trends in Ag/polyvinylidene fluoride nanocomposite optical properties. The frequency-dependent imaginary part of the dielectric constant was calculated from dipolar inter-band transitions. The metallic inclusion introduced both occupied and unoccupied states into the large polymer band gap. Thus, higher inclusion volume fractions generally led to stronger composite optical response. Spectra from monodisperse systems correlated well with nanoparticle quantum confinement models. A polydisperse system exhibited optical properties that correlated best with interparticle distances along the field direction. Nanodisk and nanorod-shaped inclusions had tunable response from field polarization, aspect ratio, crystallographic projections, and nanorod end-cap morphology.

  10. Impedance studies of the cell Ag/AgI/Ag beta alumina/AgI/Ag. Technical report No. 15, August 1987-August 1988

    SciTech Connect

    Breiter, M.W.; Drstak, H.; Maly-Schreiber, M.

    1988-07-01

    The construction of the cell Ag/AgI/Ag beta alumina/AgI/Ag is described. The impedance of this cell was measured between .001 and 10000 Hz at temperatures between 20 and 550 C. At temperatures below 100 C the cell impedance is determined to a large extent by the bulk resistance of the AgI layer and to a smaller extent by the impedance of the interface Ag/Agi. At temperatures between 160 and 350 C the impedance is controlled by the bulk resistance of the Ag beta alumina and an impedance due to contact problems between Ag and AgI. The bulk resistance of the beta' alumina becomes predominant between 350 and 550 C. A hindrance due to the transfer of silver ions from AgI to Ag beta' alumina was not observable in the whole temperature range.

  11. Fractionating nanosilver: importance for determining toxicity to aquatic test organisms.

    PubMed

    Kennedy, Alan J; Hull, Matthew S; Bednar, Anthony J; Goss, Jennifer D; Gunter, Jonas C; Bouldin, Jennifer L; Vikesland, Peter J; Steevens, Jeffery A

    2010-12-15

    This investigation applied novel techniques for characterizing and fractionating nanosilver particles and aggregates and relating these measurements to toxicological endpoints. The acute toxicity of eight nanosilver suspensions of varying primary particle sizes (10-80 nm) and coatings (citrate, polyvinylpyrrolidone, EDTA, proprietary) was assessed using three aquatic test organisms (Daphnia magna, Pimephales promelas, Pseudokirchneriella subcapitata). When 48-h lethal median concentrations (LC50) were expressed as total silver, both D. magna and P. promelas were significantly more sensitive to ionic silver (Ag(+)) as AgNO(3) (mean LC50 = 1.2 and 6.3 μg/L, respectively) relative to a wide range in LC50 values determined for the nanosilver suspensions (2 -126 μg/L). However, when LC50 values for nanosilver suspensions were expressed as fractionated nanosilver (Ag(+) and/or <4 nm particles), determined by ultracentrifugation of particles and confirmed field-flow-fractograms, the LC50 values (0.3-5.6 μg/L) were comparable to the values obtained for ionic Ag(+) as AgNO(3). These results suggest that dissolved Ag(+) plays a critical role in acute toxicity and underscores the importance of characterizing dissolved fractions in nanometal suspensions.

  12. Exposure of activated sludge to nanosilver and silver ion: Inhibitory effects and binding to the fractions of extracellular polymeric substances.

    PubMed

    Geyik, Ayse Gul; Çeçen, Ferhan

    2016-07-01

    The main aim of the study was to determine the inhibitory effects of Ag(+) and AgNP (commercial and synthesized) on activated sludge by using respirometry. Along with this aim, also the changes taking place in extracellular polymeric substances (EPS) were studied. Additionally, the binding of Ag(+) or AgNP to the different fractions in EPS was assessed using voltammetry. Synthesized AgNP led to an obvious inhibition whereas commercial AgNP had no effect on activated sludge. For Ag(+) and AgNP, IC50 values were found between 2.3-3.0mg/L and 3.2-11.1mg/L, respectively. Thus, AgNP was less inhibitory than silver ion, since the release of free silver from AgNP was very small. The protein and carbohydrate content of EPS generally increased when Ag(+) was added. Both tightly- and loosely bound fractions in EPS could bind Ag(+) and AgNP. Silver binding capacity of EPS was seen to depend on the molecular weight of proteins.

  13. Mechanistic Prediction of the Effect of Microstructural Coarsening on Creep Response of SnAgCu Solder Joints

    NASA Astrophysics Data System (ADS)

    Mukherjee, S.; Chauhan, P.; Osterman, M.; Dasgupta, A.; Pecht, M.

    2016-07-01

    Mechanistic microstructural models have been developed to capture the effect of isothermal aging on time dependent viscoplastic response of Sn3.0Ag0.5Cu (SAC305) solders. SnAgCu (SAC) solders undergo continuous microstructural coarsening during both storage and service because of their high homologous temperature. The microstructures of these low melting point alloys continuously evolve during service. This results in evolution of creep properties of the joint over time, thereby influencing the long term reliability of microelectronic packages. It is well documented that isothermal aging degrades the creep resistance of SAC solder. SAC305 alloy is aged for (24-1000) h at (25-100)°C (~0.6-0.8 × T melt). Cross-sectioning and image processing techniques were used to periodically quantify the effect of isothermal aging on phase coarsening and evolution. The parameters monitored during isothermal aging include size, area fraction, and inter-particle spacing of nanoscale Ag3Sn intermetallic compounds (IMCs) and the volume fraction of micronscale Cu6Sn5 IMCs, as well as the area fraction of pure tin dendrites. Effects of microstructural evolution on secondary creep constitutive response of SAC305 solder joints were then modeled using a mechanistic multiscale creep model. The mechanistic phenomena modeled include: (1) dispersion strengthening by coarsened nanoscale Ag3Sn IMCs in the eutectic phase; and (2) load sharing between pro-eutectic Sn dendrites and the surrounding coarsened eutectic Sn-Ag phase and microscale Cu6Sn5 IMCs. The coarse-grained polycrystalline Sn microstructure in SAC305 solder was not captured in the above model because isothermal aging does not cause any significant change in the initial grain size and orientation of SAC305 solder joints. The above mechanistic model can successfully capture the drop in creep resistance due to the influence of isothermal aging on SAC305 single crystals. Contribution of grain boundary sliding to the creep strain of

  14. Matrix fractional systems

    NASA Astrophysics Data System (ADS)

    Tenreiro Machado, J. A.

    2015-08-01

    This paper addresses the matrix representation of dynamical systems in the perspective of fractional calculus. Fractional elements and fractional systems are interpreted under the light of the classical Cole-Cole, Davidson-Cole, and Havriliak-Negami heuristic models. Numerical simulations for an electrical circuit enlighten the results for matrix based models and high fractional orders. The conclusions clarify the distinction between fractional elements and fractional systems.

  15. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles.

    PubMed

    Chaffin, Elise; O'Connor, Ryan T; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ∼410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods. PMID:27497571

  16. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Chaffin, Elise; O'Connor, Ryan T.; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ˜410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods.

  17. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles.

    PubMed

    Chaffin, Elise; O'Connor, Ryan T; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ∼410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods.

  18. Effect of Ag nanoparticle concentration on the electrical and ferroelectric properties of Ag/P(VDF-TrFE) composite films

    PubMed Central

    Paik, Haemin; Choi, Yoon-Young; Hong, Seungbum; No, Kwangsoo

    2015-01-01

    We investigated the effect of the Ag nanoparticles on the ferroelectric and piezoelectric properties of Ag/poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) composite films. We found that the remanent polarization and direct piezoelectric coefficient increased up to 12.14 μC/cm2 and 20.23 pC/N when the Ag concentration increased up to 0.005 volume percent (v%) and decreased down to 9.38 μC/cm2 and 13.45 pC/N when it increased up to 0.01 v%. Further increase in Ag concentration resulted in precipitation of Ag phase and significant leakage current that hindered any meaningful measurement of the ferroelectric and piezoelectric properties. 46% increase of the remanent polarization value and 27% increase of the direct piezoelectric coefficient were observed in the film with the 0.005 v% of the Ag nanoparticles added without significant changes to the crystalline structure confirmed by both X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) experiments. These enhancements of both the ferroelectric and piezoelectric properties are attributed to the increase in the effective electric field induced by the reduction in the effective volume of P(VDF-TrFE) that results in more aligned dipoles. PMID:26336795

  19. Effect of Ag nanoparticle concentration on the electrical and ferroelectric properties of Ag/P(VDF-TrFE) composite films

    DOE PAGES

    Paik, Haemin; Choi, Yoon -Young; Hong, Seungbum; No, Kwangsoo

    2015-09-04

    We investigated the effect of the Ag nanoparticles on the ferroelectric and piezoelectric properties of Ag/poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) composite films. We found that the remanent polarization and direct piezoelectric coefficient increased up to 12.14 μC/cm2 and 20.23 pC/N when the Ag concentration increased up to 0.005 volume percent (v%) and decreased down to 9.38 μC/cm2 and 13.45 pC/N when it increased up to 0.01 v%. Further increase in Ag concentration resulted in precipitation of Ag phase and significant leakage current that hindered any meaningful measurement of the ferroelectric and piezoelectric properties. 46% increase of the remanent polarization value and 27% increasemore » of the direct piezoelectric coefficient were observed in the film with the 0.005 v% of the Ag nanoparticles added without significant changes to the crystalline structure confirmed by both X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) experiments. The enhancements of both the ferroelectric and piezoelectric properties are attributed to the increase in the effective electric field induced by the reduction in the effective volume of P(VDF-TrFE) that results in more aligned dipoles.« less

  20. Effect of Ag nanoparticle concentration on the electrical and ferroelectric properties of Ag/P(VDF-TrFE) composite films

    SciTech Connect

    Paik, Haemin; Choi, Yoon -Young; Hong, Seungbum; No, Kwangsoo

    2015-09-04

    We investigated the effect of the Ag nanoparticles on the ferroelectric and piezoelectric properties of Ag/poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) composite films. We found that the remanent polarization and direct piezoelectric coefficient increased up to 12.14 μC/cm2 and 20.23 pC/N when the Ag concentration increased up to 0.005 volume percent (v%) and decreased down to 9.38 μC/cm2 and 13.45 pC/N when it increased up to 0.01 v%. Further increase in Ag concentration resulted in precipitation of Ag phase and significant leakage current that hindered any meaningful measurement of the ferroelectric and piezoelectric properties. 46% increase of the remanent polarization value and 27% increase of the direct piezoelectric coefficient were observed in the film with the 0.005 v% of the Ag nanoparticles added without significant changes to the crystalline structure confirmed by both X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) experiments. The enhancements of both the ferroelectric and piezoelectric properties are attributed to the increase in the effective electric field induced by the reduction in the effective volume of P(VDF-TrFE) that results in more aligned dipoles.

  1. Restructuring hollow Au–Ag nanostructures for improved SERS activity

    NASA Astrophysics Data System (ADS)

    Jiji, S. G.; Gopchandran, K. G.

    2016-10-01

    Hollow Au–Ag nanostructures with improved SERS performance were prepared by using a modified galvanic replacement reaction. The plasmon characteristics of the hollow structures are found to be highly sensitive to the volume of cathode, whether or not a co-reductant was used in the synthesis. It is found that the presence of a co-reductant viz., ascorbic acid (AA) during the reaction make the hollow structures capable to maintain its physical structure even after addition of excess cathode and also it transformes sacrificial templates into highly efficient hollow Au–Ag SERS substrates. In the galvanic replacement reaction conducted in presence of AA, where on one side the removal of Ag atoms make cavities to occur and on the other side a coating on the surface with Au and Ag atoms due to co-reduction take place simultaneously. Morphological observations indicated that it is possible to control the competition between these two mechanisms and to make Au–Ag hollow structures in tune with applications by optimizing the volume of cathode or AA. The SERS activity of these substrates were tested with crystal violet molecule as probe, using two different laser lines, 514 and 784.8 nm. In this report, the enhancement observed for hollow structures fabricated under optimum conditions are in the order of 106. SERS measurements have shown that for a specific volume of cathode, substrates fabricated in presence of AA are superior to the other type and also the increase in enhancement factor is ∼10 fold.

  2. Liter - Metric Volume.

    ERIC Educational Resources Information Center

    Sisk, Diane

    This autoinstructional program, developed as part of a general science course, is offered for students in the middle schools. Mathematics of fractions and decimals is considered to be prerequisite knowledge. The behavioral objectives are directed toward mastery of determining volumes of solid objects using the water displacement method as well as…

  3. Effect of Ag and Pb Addition on Microstructural and Mechanical Properties of SAC 105 Solders

    NASA Astrophysics Data System (ADS)

    Molnar, Aliz; Janovszky, Dora; Kardos, Ibolya; Molnar, Istvan; Gacsi, Zoltan

    2015-10-01

    Melting and crystallization processes of lead-free and lead-contaminated alloys in near-equilibrium state were investigated. In addition, the effect of silver content up to 4 wt.% on the microstructure of Sn-Ag-Cu alloys was studied. The volume fraction of β-Sn decreased by half owing to 4 wt.% Ag content. Furthermore, contamination by lead strongly influences the properties of the solidified microstructure. The Pb grains appear as a result of two processes when the Pb content is equal to 0.5 wt.% or higher: Pb phase solidifies in the quaternary eutectic at 176°C, and Pb grains precipitate from the primary β-Sn solid solution grain during a solid state reaction. The freezing range enlarges to 51°C due to 2 wt.% Pb content owing to quaternary eutectic. Above 1 wt.% Pb content, the mechanical properties also improve due to grains of quaternary eutectic Pb and precipitated Pb grains with a size <1 μm.

  4. Annealing behaviour of c-SiO 2 implanted layer distributed with high density Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Zhengxin; Wang, Honghong

    1997-01-01

    High volume density Ag nanoparticles embedded in c-SiO 2 matrix have been prepared by Ag ion implantation at an energy of 200 keV and a current density of about 20 μA/cm 2 to a nominal dose of 6.7 × 10 16ions/cm 2 at RT. Bright-field transmission electron microscopy (TEM) image indicates that Ag nanoparticles show two groups of sizes: the larger diameter is about 25 nm and the smaller is less than 10 nm. RBS spectra show that the distribution of implanted Ag atoms is bimodal which is associated with the two groups of nanoparticles above. Thermal stability of the implanted layer which consists of Ag nanoparticles, dissolved Ag atoms and c-SiO 2 matrix has been investigated by RBS, TEM and Raman spectroscopy. RBS spectra prove that little migration of Ag atoms is found and Ag nanoparticles are considerably stable at 300°C annealing. Though the obvious change in the distribution of Ag is observed at 400°C annealing in RBS spectra, TEM image identifies that both the larger and the smaller Ag nanoparticles still exist at relatively stable state. Following 750°C annealing, Ag atoms drastically move, and furthermore, the bimodal character of the distribution disappears. On the other hand, the amorphized SiO 2 implanted layer recrystal after 300°C, 400°C annealing.

  5. Initialized Fractional Calculus

    NASA Technical Reports Server (NTRS)

    Lorenzo, Carl F.; Hartley, Tom T.

    2000-01-01

    This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.

  6. Grain boundary diffusion of Ag through polycrystalline SiC in TRISO fuel particles

    NASA Astrophysics Data System (ADS)

    Deng, Jie; Ko, Hyunseok; Demkowicz, Paul; Morgan, Dane; Szlufarska, Izabela

    2015-12-01

    The effective diffusivity and release fraction of Ag in polycrystalline SiC are evaluated using a kinetic Monte Carlo model. The effects of various grain boundary network properties on the transport of Ag across the SiC layer have been examined, including fraction of grain boundary type, spread in grain boundary diffusivities and distribution of grain boundary types. It is shown that the effective diffusivity and release fraction of Ag can exhibit a large variability due to changes in the GB structure of SiC, and this variability is almost independent of temperature fluctuation. The present results suggest that the variation in properties of grain boundary networks in SiC may contribute to the spread in the Ag diffusivity and release fraction measured in TRISO particles. It is also found that the grain boundary diffusion alone may be insufficient to account for the Ag diffusivities and release fractions measured in integral release experiments. Additional factors such as irradiation and temperature distribution may also play an important role in Ag transport across the SiC layer.

  7. Ag Division States Philosophy

    ERIC Educational Resources Information Center

    American Vocational Journal, 1976

    1976-01-01

    The discussion which took place during the American Vocational Association's (AVA) Agriculture Division meeting at the 1975 AVA Convention is summarized, and the statement of vo-ag education philosophy (including 13 key concepts), which was passed during the convention, is presented. (AJ)

  8. Tempered fractional calculus

    NASA Astrophysics Data System (ADS)

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  9. Tempered fractional calculus

    SciTech Connect

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-15

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  10. Freeze-dried PVP-Ag+ precursors to novel AgBr/AgCl-Ag hybrid nanocrystals for visible-light-driven photodegradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Chen, Deliang; Chen, Qianqian; Zhang, Wenjie; Ge, Lianfang; Shao, Gang; Fan, Bingbing; Lu, Hongxia; Zhang, Rui; Yang, Daoyuan; Shao, Guosheng

    2015-04-01

    AgBr/AgCl-Ag nanocrystals with various molar Br-to-Ag ratios (RBr/Ag = 0, 1/3, 1/2, 2/3, 1) and different photoreduction times (0-20 min) were synthesized via stepwise liquid-solid reactions using the freeze-dried PVP-Ag+ hybrid as the Ag source, followed by a photoreduction reaction. The AgBr/AgCl-Ag7.5(1:2) nanocrystals obtained take on a spherical morphology with a particle-size range of 58 ± 15 nm. The photocatalytic performance of AgBr/AgCl-Ag nanocrystals was evaluated by photodegrading organic dyes, 4-chlorophenol and isopropanol under artificial visible light (λ ⩾ 420 nm, 100 mW cm-2). For the decomposition of rhodamine B, the AgBr/AgCl-Ag7.5(1:2) nanocrystals has a photodegradation rate of ∼0.87 min-1, ∼159 times higher than that (∼0.0054 min-1) of TiO2 (P25), whereas the AgCl-Ag and AgBr-Ag nanocrystals have photodegradation rates of 0.35 min-1 and 0.45 min-1, respectively. The efficient separation of photogenerated electron-hole pairs in the ternary system consisting of AgBr, AgCl and Ag species plays a key role in the enhancement of photocatalytic performance.

  11. AGS experiments -- 1995, 1996 and 1997

    SciTech Connect

    Depken, J.C.; Presti, P.L.

    1997-12-01

    This report contains (1) FY 1995 AGS schedule as run; (2) FY 1996 AGS schedule as run; (3) FY 1997 AGS schedule as run; (4) FY 1998--1999 AGS schedule (proposed); (5) AGS beams 1997; (6) AGS experimental area FY 1995 physics program; (7) AGS experimental area FY 1996 physics program; (8) AGS experimental area FY 1997 physics program; (9) AGS experimental area FY 1998--1999 physics program (proposed); (10) a listing of experiments by number; (11) two-page summaries of each experiment, in order by number; and (12) listing of publications of AGS experiments.

  12. AGS experiments -- 1991, 1992, 1993. Tenth edition

    SciTech Connect

    Depken, J.C.

    1994-04-01

    This report contains: (1) FY 1993 AGS schedule as run; (2) FY 1994--95 AGS schedule; (3) AGS experiments {ge} FY 1993 (as of 30 March 1994); (4) AGS beams 1993; (5) AGS experimental area FY 1991 physics program; (6) AGS experimental area FY 1992 physics program; (7) AGS experimental area FY 1993 physics program; (8) AGS experimental area FY 1994 physics program (planned); (9) a listing of experiments by number; (10) two-page summaries of each experiment; (11) listing of publications of AGS experiments; and (12) listing of AGS experiments.

  13. TEMPERED FRACTIONAL CALCULUS

    PubMed Central

    MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA

    2014-01-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series. PMID:26085690

  14. Destabilization of Ag nanoislands on Ag(100) by adsorbed sulfur

    SciTech Connect

    Shen, Mingmin; Russell, Selena M.; Liu, Da-Jiang; Thiel, Patricia A.

    2011-10-17

    Sulfur accelerates coarsening of Ag nanoislands on Ag(100) at 300 K, and this effect is enhanced with increasing sulfur coverage over a range spanning a few hundredths of a monolayer, to nearly 0.25 monolayers. We propose that acceleration of coarsening in this system is tied to the formation of AgS{sub 2} clusters primarily at step edges. These clusters can transport Ag more efficiently than can Ag adatoms (due to a lower diffusion barrier and comparable formation energy). The mobility of isolated sulfur on Ag(100) is very low so that formation of the complex is kinetically limited at low sulfur coverages, and thus enhancement is minimal. However, higher sulfur coverages force the population of sites adjacent to step edges, so that formation of the cluster is no longer limited by diffusion of sulfur across terraces. Sulfur exerts a much weaker effect on the rate of coarsening on Ag(100) than it does on Ag(111). This is consistent with theory, which shows that the difference between the total energy barrier for coarsening with and without sulfur is also much smaller on Ag(100) than on Ag(111).

  15. Columbia River Basin Seasonal Volumes and Statistics, 1928-1989. 1990 Level Modified Streamflows Computed Seasonal Volumes 61-Year Statistics.

    SciTech Connect

    A.G. Crook Company

    1993-04-01

    This report was prepared by the A.G. Crook Company, under contract to Bonneville Power Administration, and provides statistics of seasonal volumes and streamflow for 28 selected sites in the Columbia River Basin.

  16. AGS preinjector improvement

    SciTech Connect

    Alessi, J.G.; Brennan, J.M.; Brown, H.N.; Brodowski, J.; Gough, R.; Kponou, A.; Prelec, K.; Staples, J.; Tanabe, J.; Witkover, R.

    1987-01-01

    In 1984, a polarized H/sup -/ source was installed to permit the acceleration of polarized protons in the AGS, using a low current, 750 keV RFQ Linear Accelerator as the preinjector. This RFQ was designed by LANL and has proved to be quite satisfactory and reliable. In order to improve the reliability and simplify maintenance of the overall AGS operations, it has been decided to replace one of the two 750 keV Cockcroft-Waltons (C-W) with an RFQ. The design of a new high current RFQ has been carried out by LBL and is also being constructed there. This paper describes the preinjector improvement project, centered around that RFQ, which is underway at BNL.

  17. Activity and stability studies of titanates and titanate-carbon nanotubes supported Ag anode catalysts for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Mohamed, Mohamed Mokhtar; Khairy, M.; Eid, Salah

    2016-02-01

    Titanate-SWCNT; synthesized via exploiting the interaction between TiO2 anatase with oxygen functionalized SWCNT, supported Ag nanoparticles and Ag/titanate are characterized using XRD, TEM-EDX-SAED, N2 adsorption, Photoluminescence, Raman and FTIR spectroscopy. These samples are tested for methanol electrooxidation via using cyclic voltammetry (CV) and impedance measurements. It is shown that Ag/titanate nanotubes exhibited superior electrocatalytic performance for methanol oxidation (4.2 mA cm-2) than titanate-SWCNT, Ag/titanate-SWCNT and titanate. This study reveals the existence of a strong metal-support interaction in Ag/titanate as explored via formation of Ti-O-Ag bond at 896 cm-1 and increasing surface area and pore volume (103 m2 g-1, 0.21 cm3 g-1) compared to Ag/titanate-SWCNT (71 m2 g-1, 0.175 cm3 g-1) that suffers perturbation and defects following incorporation of SWCNT and Ag. Embedding Ag preferably in SWCNT rather than titanate in Ag/titanate-SWCNT disturbs the electron transfer compared to Ag/titanate. Charge transfer resistance depicted from Nyquist impedance plots is found in the order of titanate > Ag/titanate-SWCNT > titanate-SWCNT > Ag/titanate. Accordingly, Ag/titanate indicates a slower current degradation over time compared to rest of catalysts. Conductivity measurements indicate that it follows the order Ag/titanate > Ag/titanate-SWCNT > titanate > titanate-SWCNT declaring that SWCNT affects seriously the conductivity of Ag(titanate) due to perturbations caused in titanate and sinking of electrons committed by Ago through SWCNT.

  18. Free volume under shear

    NASA Astrophysics Data System (ADS)

    Maiti, Moumita; Vinutha, H. A.; Sastry, Srikanth; Heussinger, Claus

    2015-10-01

    Using an athermal quasistatic simulation protocol, we study the distribution of free volumes in sheared hard-particle packings close to, but below, the random-close packing threshold. We show that under shear, and independent of volume fraction, the free volumes develop features similar to close-packed systems — particles self-organize in a manner as to mimick the isotropically jammed state. We compare athermally sheared packings with thermalized packings and show that thermalization leads to an erasure of these structural features. The temporal evolution in particular the opening-up and the closing of free-volume patches is associated with the single-particle dynamics, showing a crossover from ballistic to diffusive behavior.

  19. Free volume under shear.

    PubMed

    Maiti, Moumita; Vinutha, H A; Sastry, Srikanth; Heussinger, Claus

    2015-10-14

    Using an athermal quasistatic simulation protocol, we study the distribution of free volumes in sheared hard-particle packings close to, but below, the random-close packing threshold. We show that under shear, and independent of volume fraction, the free volumes develop features similar to close-packed systems - particles self-organize in a manner as to mimick the isotropically jammed state. We compare athermally sheared packings with thermalized packings and show that thermalization leads to an erasure of these structural features. The temporal evolution in particular the opening-up and the closing of free-volume patches is associated with the single-particle dynamics, showing a crossover from ballistic to diffusive behavior.

  20. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles. Part 1. Aggregation and dissolution.

    PubMed

    Unrine, Jason M; Colman, Benjamin P; Bone, Audrey J; Gondikas, Andreas P; Matson, Cole W

    2012-07-01

    To better understand their fate and toxicity in aquatic environments, we compared the aggregation and dissolution behavior of gum arabic (GA) and polyvinylpyrrolidone (PVP) coated Ag nanoparticles (NPs) in aquatic microcosms. There were four microcosm types: surface water; water and sediment; water and aquatic plants; or water, sediment, and aquatic plants. Dissolution and aggregation behavior of AgNPs were examined using ultracentrifugation, ultrafiltration, and asymmetrical flow field flow fractionation coupled to ultraviolet-visible spectroscopy, dynamic and static laser light scattering, and inductively coupled plasma mass spectrometry. Plants released dissolved organic matter (DOM) into the water column either through active or passive processes in response to Ag exposure. This organic matter fraction readily bound Ag ions. The plant-derived DOM had the effect of stabilizing PVP-AgNPs as primary particles, but caused GA-AgNPs to be removed from the water column, likely by dissolution and binding of released Ag ions on sediment and plant surfaces. The destabilization of the GA-AgNPs also corresponded with X-ray absorption near edge spectroscopy results which suggest that 22-28% of the particulate Ag was associated with thiols and 5-14% was present as oxides. The results highlight the potential complexities of nanomaterial behavior in response to biotic and abiotic modifications in ecosystems, and may help to explain differences in toxicity of Ag observed in realistic exposure media compared to simplified laboratory exposures.

  1. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  2. Bipolar Ag-Zn battery

    NASA Technical Reports Server (NTRS)

    Giltner, L. John

    1994-01-01

    The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected

  3. Ag-Air Service

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Econ, Inc.'s agricultural aerial application, "ag-air," involves more than 10,000 aircraft spreading insecticides, herbicides, fertilizer, seed and other materials over millions of acres of farmland. Difficult for an operator to estimate costs accurately and decide what to charge or which airplane can handle which assignment most efficiently. Computerized service was designed to improve business efficiency in choice of aircraft and determination of charge rates based on realistic operating cost data. Each subscriber fills out a detailed form which pertains to his needs and then receives a custom-tailored computer printout best suited to his particular business mix.

  4. Communication: Structure, formation, and equilibration of ensembles of Ag-S complexes on an Ag surface

    SciTech Connect

    Russell, Selena M.; Kim, Yousoo; Liu, Da-Jiang; Evans, J. W.; Thiel, P. A.

    2013-02-15

    We have utilized conditions of very low temperature (4.7 K) and very low sulfur coverage to isolate and identify Ag-S complexes that exist on the Ag(111) surface. The experimental conditions are such that the complexes form at temperatures above the temperature of observation. These complexes can be regarded as polymeric chains of varying length, with an Ag4S pyramid at the core of each monomeric unit. Steps may catalyze the formation of the chains and this mechanism may be reflected in the chain length distribution.

  5. Dividing Fractions: A Pedagogical Technique

    ERIC Educational Resources Information Center

    Lewis, Robert

    2016-01-01

    When dividing one fraction by a second fraction, invert, that is, flip the second fraction, then multiply it by the first fraction. To multiply fractions, simply multiply across the denominators, and multiply across the numerators to get the resultant fraction. So by inverting the division of fractions it is turned into an easy multiplication of…

  6. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  7. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule ``as run``; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  8. Toward full spectrum speciation of silver nanoparticles and ionic silver by on-line coupling of hollow fiber flow field-flow fractionation and minicolumn concentration with multiple detectors.

    PubMed

    Tan, Zhi-Qiang; Liu, Jing-Fu; Guo, Xiao-Ru; Yin, Yong-Guang; Byeon, Seul Kee; Moon, Myeong Hee; Jiang, Gui-Bin

    2015-08-18

    The intertransformation of silver nanoparticles (AgNPs) and ionic silver (Ag(I)) in the environment determines their transport, uptake, and toxicity, demanding methods to simultaneously separate and quantify AgNPs and Ag(I). For the first time, hollow fiber flow field-flow fractionation (HF5) and minicolumn concentration were on-line coupled together with multiple detectors (including UV-vis spectrometry, dynamic light scattering, and inductively coupled plasma mass spectrometry) for full spectrum separation, characterization, and quantification of various Ag(I) species (i.e., free Ag(I), weak and strong Ag(I) complexes) and differently sized AgNPs. While HF5 was employed for filtration and fractionation of AgNPs (>2 nm), the minicolumn packed with Amberlite IR120 resin functioned to trap free Ag(I) or weak Ag(I) complexes coming from the radial flow of HF5 together with the strong Ag(I) complexes and tiny AgNPs (<2 nm), which were further discriminated in a second run of focusing by oxidizing >90% of tiny AgNPs to free Ag(I) and trapped in the minicolumn. The excellent performance was verified by the good agreement of the characterization results of AgNPs determined by this method with that by transmission electron microscopy, and the satisfactory recoveries (70.7-108%) for seven Ag species, including Ag(I), the adduct of Ag(I) and cysteine, and five AgNPs with nominal diameters of 1.4 nm, 10 nm, 20 nm, 40 nm, and 60 nm in surface water samples. PMID:26222150

  9. Bioaccumulation of Zn and Ag Nanoparticles in the Earthworms (Eisenia fetida)

    NASA Astrophysics Data System (ADS)

    Ha, Lee Seung; Sung-Dae, Kim; Yi, Yang Song; Byeong-Gweon, Lee

    2014-05-01

    present mainly in HSP (heat-sensitive protein) while cellullar Ag from Ag ion and AgNPs (Ag/PVP, Ag/citrate) treatments were found mostly in cellular debris. No statistical difference in partitioning of metals among different subcelluar pools was found between the metal forms. Zn from ZnO contaminated solis was found largely in carbonate fraction (41%), while Zn from Zn ion treatment was found in Fe-Mn Oxide (29%). Association of Zn to mobile fractions (ZnO; 65%, Zn ion; 35%) suggest that Zn from ZnO contaminated soil would be more bioavailable than that from Zn ion treatment. However, the BAFs for Zn in the animals did not follow this prediction. Majority of Ag from AgNPs or Ag ion contaminated soil was bound mainly to biologically inert fractions mainly in organic matter, surphide fractions, and residual fractions. Consistent with these findings, the BAFs of Ag in the worms exposed to Ag contaminated soils were generally lower than those for Zn treatments.

  10. Estimation of the fractional coverage of rainfall in climate models

    NASA Technical Reports Server (NTRS)

    Eltahir, E. A. B.; Bras, R. L.

    1993-01-01

    The fraction of the grid cell area covered by rainfall, mu, is an essential parameter in descriptions of land surface hydrology in climate models. A simple procedure is presented for estimating this fraction, based on extensive observations of storm areas and rainfall volumes. Storm area and rainfall volume are often linearly related; this relation can be used to compute the storm area from the volume of rainfall simulated by a climate model. A formula is developed for computing mu, which describes the dependence of the fractional coverage of rainfall on the season of the year, the geographical region, rainfall volume, and the spatial and temporal resolution of the model. The new formula is applied in computing mu over the Amazon region. Significant temporal variability in the fractional coverage of rainfall is demonstrated. The implications of this variability for the modeling of land surface hydrology in climate models are discussed.

  11. An Appetite for Fractions

    ERIC Educational Resources Information Center

    Wilkerson, Trena L.; Bryan, Tommy; Curry, Jane

    2012-01-01

    This article describes how using candy bars as models gives sixth-grade students a taste for learning to represent fractions whose denominators are factors of twelve. Using paper models of the candy bars, students explored and compared fractions. They noticed fewer different representations for one-third than for one-half. The authors conclude…

  12. (Carbon isotope fractionation inplants)

    SciTech Connect

    O'Leary, M.H.

    1990-01-01

    The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

  13. The Future of Fractions

    ERIC Educational Resources Information Center

    Usiskin, Zalman P.

    2007-01-01

    In the 1970s, the movement to the metric system (which has still not completely occurred in the United States) and the advent of hand-held calculators led some to speculate that decimal representation of numbers would render fractions obsolete. This provocative proposition stimulated Zalman Usiskin to write "The Future of Fractions" in 1979. He…

  14. New Enzyme Immunoassay for Detection of Hepatitis B Virus Core Antigen (HBcAg) and Relation between Levels of HBcAg and HBV DNA

    PubMed Central

    Kimura, Tatsuji; Rokuhara, Akinori; Matsumoto, Akihiro; Yagi, Shintaro; Tanaka, Eiji; Kiyosawa, Kendo; Maki, Noboru

    2003-01-01

    A new enzyme immunoassay specific for hepatitis B virus (HBV) core antigen (HBcAg) was developed. In order to detect HBcAg, specimens were pretreated with detergents to release HBcAg from the HBV virion and disassemble it to dimers, and simultaneously, the treatment inactivated anti-HBc antibodies. HBcAg detected by the assay peaked with HBV DNA in density gradient fractions of HBV-positive sera. The assay showed a wide detection range from 2 to 100,000 pg/ml. We observed no interference from anti-HBc antibody or blood components, but the assay was inhibited by very high concentrations (>1 μg/ml; corresponding to 80 signal/cutoff) of HBeAg. When the cutoff value was tentatively set at 4 pg/ml, all healthy control (HBsAg and HBV DNA negative, n = 160) and anti-hepatitis C virus-positive (n = 55) sera were identified as negative. HBcAg concentrations correlated very closely with HBV DNA (r = 0.946, n = 145) in 216 samples from 72 hepatitis B patients. In seroconversion panels, HBcAg concentrations changed in parallel with HBV DNA levels. The assay, therefore, offers a simple method for monitoring hepatitis B patients. With a series of sera during lamivudine therapy, HBV DNA levels fell sharply and the HBcAg concentration also decreased, but the change in HBcAg was smaller and more gradual. The supposed mechanism of these changes and their clinical significance are discussed. PMID:12734224

  15. The AGS-Booster lattice

    SciTech Connect

    Lee, Y.Y.; Barton, D.S.; Claus, J.; Cottingham, J.G.; Courant, E.D.; Danby, G.T.; Dell, G.F.; Forsyth, E.B.; Gupta, R.C.; Kats, J.

    1987-01-01

    The AGS Booster has three objectives. They are to increase the space charge limit of the AGS, to increase the intensity of the polarized proton beam by accumulating many linac pulses (since the intensity is limited by the polarized ion source), and to reaccelerate heavy ions from the BNL Tandem Van de Graaff before injection into the AGS. The machine is capable of accelerating protons at 7.5 Hertz from 200 MeV to 1.5 GeV or to lower final energies at faster repetition rates. The machine will also be able to accelerate heavy ions from as low as 1 MeV/nucleon to a magnetic rigidity as high as 17.6 Tesla-meters with a one second repetition rate. As an accumulator for polarized protons, the Booster should be able to store the protons at 200 MeV for several seconds. We expect that the Booster will increase the AGS proton intensity by a factor of four, polarized proton intensity by a factor of twenty to thirty, and will also enable the AGS to accelerate all species of heavy ions (at present the AGS heavy ion program is limited to the elements lighter than sulfur because it can only accelerate fully stripped ions). The construction project started in FY 1985 and is expected to be completed in 1989. The purpose of this paper is to provide a future reference for the AGS Booster lattice.

  16. Antinociceptive Activity of the Ethanolic Extract, Fractions, and Aggregatin D Isolated from Sinningia aggregata Tubers

    PubMed Central

    Souza, Geórgea V.; Bastos-Pereira, Amanda L.; Frois, Gisele R. A.; Ribas, João L. C.; Verdan, Maria H.; Kassuya, Cândida A. L.; Stefanello, Maria E.; Zampronio, Aleksander R.

    2015-01-01

    The present study investigated the effects of the ethanolic extract (ESa), fractions, and compounds isolated from Sinningia aggregata in male Swiss mice on carrageenan-induced paw edema, neutrophil migration, mechanical hyperalgesia, formalin-induced nociception, and lipopolysaccharide-induced fever. The ESa did not alter edema, neutrophil migration, or fever at any of the doses tested. However, the ESa reduced phase II of formalin-induced nociception and carrageenan-induced mechanical hyperalgesia. The petroleum ether (PE) and ethyl acetate (EA) fractions and aggregatin D (AgD; isolated from the EA fraction) reduced formalin-induced nociception. Anthraquinones from the PE fraction were ineffective. AgD also inhibited carrageenan-induced mechanical hyperalgesia. Neither the ESa nor AgD altered thermal nociception or motor performance. Local administration of AgD also reduced hyperalgesia induced by carrageenan, bradykinin, tumor necrosis factor-α, interleukin-1β, cytokine-induced neutrophil chemoattractant, prostaglandin E2, and dopamine but not hyperalgesia induced by forskolin or dibutyryl cyclic adenosine monophosphate. The positive control dipyrone reduced the response induced by all of the stimuli. Additionally, glibenclamide abolished the analgesic effect of dipyrone but not the one induced by AgD. AgD did not change lipopolysaccharide-induced nitric oxide production by macrophages or the nociception induced by capsaicin, cinnamaldehyde, acidified saline, or menthol. These results suggest that the ESa has important antinociceptive activity, and this activity results at least partially from the presence of AgD. AgD reduced mechanical hyperalgesia induced by several inflammatory mediators through mechanisms that are different from classic analgesic drugs. PMID:25719394

  17. Fractional calculus in bioengineering.

    PubMed

    Magin, Richard L

    2004-01-01

    Fractional calculus (integral and differential operations of noninteger order) is not often used to model biological systems. Although the basic mathematical ideas were developed long ago by the mathematicians Leibniz (1695), Liouville (1834), Riemann (1892), and others and brought to the attention of the engineering world by Oliver Heaviside in the 1890s, it was not until 1974 that the first book on the topic was published by Oldham and Spanier. Recent monographs and symposia proceedings have highlighted the application of fractional calculus in physics, continuum mechanics, signal processing, and electromagnetics, but with few examples of applications in bioengineering. This is surprising because the methods of fractional calculus, when defined as a Laplace or Fourier convolution product, are suitable for solving many problems in biomedical research. For example, early studies by Cole (1933) and Hodgkin (1946) of the electrical properties of nerve cell membranes and the propagation of electrical signals are well characterized by differential equations of fractional order. The solution involves a generalization of the exponential function to the Mittag-Leffler function, which provides a better fit to the observed cell membrane data. A parallel application of fractional derivatives to viscoelastic materials establishes, in a natural way, hereditary integrals and the power law (Nutting/Scott Blair) stress-strain relationship for modeling biomaterials. In this review, I will introduce the idea of fractional operations by following the original approach of Heaviside, demonstrate the basic operations of fractional calculus on well-behaved functions (step, ramp, pulse, sinusoid) of engineering interest, and give specific examples from electrochemistry, physics, bioengineering, and biophysics. The fractional derivative accurately describes natural phenomena that occur in such common engineering problems as heat transfer, electrode/electrolyte behavior, and sub

  18. Fractional calculus in bioengineering.

    PubMed

    Magin, Richard L

    2004-01-01

    Fractional calculus (integral and differential operations of noninteger order) is not often used to model biological systems. Although the basic mathematical ideas were developed long ago by the mathematicians Leibniz (1695), Liouville (1834), Riemann (1892), and others and brought to the attention of the engineering world by Oliver Heaviside in the 1890s, it was not until 1974 that the first book on the topic was published by Oldham and Spanier. Recent monographs and symposia proceedings have highlighted the application of fractional calculus in physics, continuum mechanics, signal processing, and electromagnetics, but with few examples of applications in bioengineering. This is surprising because the methods of fractional calculus, when defined as a Laplace or Fourier convolution product, are suitable for solving many problems in biomedical research. For example, early studies by Cole (1933) and Hodgkin (1946) of the electrical properties of nerve cell membranes and the propagation of electrical signals are well characterized by differential equations of fractional order. The solution involves a generalization of the exponential function to the Mittag-Leffler function, which provides a better fit to the observed cell membrane data. A parallel application of fractional derivatives to viscoelastic materials establishes, in a natural way, hereditary integrals and the power law (Nutting/Scott Blair) stress-strain relationship for modeling biomaterials. In this review, I will introduce the idea of fractional operations by following the original approach of Heaviside, demonstrate the basic operations of fractional calculus on well-behaved functions (step, ramp, pulse, sinusoid) of engineering interest, and give specific examples from electrochemistry, physics, bioengineering, and biophysics. The fractional derivative accurately describes natural phenomena that occur in such common engineering problems as heat transfer, electrode/electrolyte behavior, and sub

  19. Low temperature vitrification of radioiodine using AgI-Ag{sub 2}O-P{sub 2}O{sub 5} glass system

    SciTech Connect

    Fujihara, H.; Murase, T.; Nishi, T.; Noshita, K. Yoshida, T.; Matsuda, M.

    1999-07-01

    A new vitrification process for radioiodine has been developed for safe disposal of the spent iodine adsorbent generated from reprocessing off-gas systems. The proposed process consists of the following two steps: (1) separation of radioiodine as AgI from spent iodine adsorbent and (2) vitrification of the separated AgI with silver phosphate. An AgI-Ag{sub 2}O-P{sub 2}O{sub 5} glass system can homogeneously contain up to 60 mol% AgI, which leads to high volume reduction efficiency (approximately 1/25). It also can vitrify the AgI without volatilization of iodine because of its low melting temperature (below 400 C). The leachabilities of iodine from simulated vitrified waste forms were evaluated by the MCC-1 static leach test in an anaerobically controlled glove box, which was purged by nitrogen gas with 3% hydrogen. The leaching behavior of the AgI-Ag{sub 2}O-P{sub 2}O{sub 5} glass system was influenced by the composition of the actual glass, type of leachant, and redox conditions. When the leach test was carried out using simulated ground water originating from rainfall, the leach rate of iodine from 3AgI-Ag{sub 4}P{sub 2}O{sub 7} glass was 6 x 10{sup {minus}8}g/cm{sup 2}/d in the early period of the leach test at 35 C under the reducing condition, after which it decreased to 3 x 10{sup {minus}9}g/cm{sup 2}/d. This glass showed a lower leach rate in the simulated ground water originating from sea water or cement saturated water, since a precipitation layer was formed on the surface.

  20. Spin dynamics simulations at AGS

    SciTech Connect

    Huang, H.; MacKay, W.W.; Meot, F.; Roser, T.

    2010-05-23

    To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electromagnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.

  1. Multielement analysis of metal-binding proteins in cytosol fractions.

    PubMed

    Bray, J T; Webb, L A; Reilly, F J

    1983-06-01

    The distribution of 24 elements among the cytosol protein fractions was determined for specimens of the bivalve mollusc Macoma balthica obtained from three estuarine locations subject to varying levels of metal pollution and on specimens of Rangia cuneata from three areas subject to varying degrees of thermal pollution. Of the 24 elements examined 15 occurred at levels above detection limits and in association with one or more of four distinct protein fractions. Levels of Ag and Cu associated with high molecular weight proteins and with "metallothionein-like" proteins permitted identification of those Macoma balthica specimens exposed to the greatest degree of metal stress.

  2. High-performance polyimide nanocomposites with core-shell AgNWs@BN for electronic packagings

    NASA Astrophysics Data System (ADS)

    Zhou, Yongcun; Liu, Feng

    2016-08-01

    The increasing density of electronic devices underscores the need for efficient thermal management. Silver nanowires (AgNWs), as one-dimensional nanostructures, possess a high aspect ratio and intrinsic thermal conductivity. However, high electrical conductivity of AgNWs limits their application for electronic packaging. We synthesized boron nitride-coated silver nanowires (AgNWs@BN) using a flexible and fast method followed by incorporation into synthetic polyimide (PI) for enhanced thermal conductivity and dielectric properties of nanocomposites. The thinner boron nitride intermediate nanolayer on AgNWs not only alleviated the mismatch between AgNWs and PI but also enhanced their interfacial interaction. Hence, the maximum thermal conductivity of an AgNWs@BN/PI composite with a filler loading up to 20% volume was increased to 4.33 W/m K, which is an enhancement by nearly 23.3 times compared with that of the PI matrix. The relative permittivity and dielectric loss were about 9.89 and 0.015 at 1 MHz, respectively. Compared with AgNWs@SiO2/PI and Ag@BN/PI composites, boron nitride-coated core-shell structures effectively increased the thermal conductivity and reduced the permittivity of nanocomposites. The relative mechanism was studied and discussed. This study enables the identification of appropriate modifier fillers for polymer matrix nanocomposites.

  3. Stable Chlorine Isotope Fractionation

    NASA Astrophysics Data System (ADS)

    Sharp, Z.

    2006-12-01

    Chlorine isotope partitioning between different phases is not well understood. Pore fluids can have δ37Cl values as low as -8‰, with neoform sediments having strongly positive values. Most strikingly, volcanic gases have δ37Cl values that cover a range in excess of 14‰ (Barnes et al., this meeting). The large range is difficult to explain in terms of equilibrium fractionation, which, although calculated to be very large for Cl in different oxidation states, should be less than 2‰ between chloride species (Schauble et al., 2003, GCA). To address the discrepancy between Nature and theory, we have measured Cl isotope fractionation for selected equilibrium and disequilibrium experiments in order to identify mechanisms that might lead to large fractionations. 1) NaCl (s,l) NaCl (v): NaCl was sealed in an evacuated silica tube and heated at one end, causing vaporization and reprecipitation of NaCl (v) at the cool end of the tube. The fractionation is 0.2‰ at 700°C (halite-vapor) and 0.7‰ at 800°C (liquid-vapor), respectively. The larger fractionation at higher temperature may be related to equilibrium fractionation between liquid and gas vs. `stripping' of the solid in the lower T experiments. 2) Sodalite NaCl(l): Nepheline and excess NaCl were sealed in a Pt crucible at 825°C for 48 hrs producing sodalite. The measured newly-formed sodalite-NaCl fractionation is -0.2‰. 3) Volatilization of HCl: Dry inert gas was bubbled through HCl solutions and the vapor was collected in a downstream water trap. There was no fractionation for 12.4M HCl (HCl fuming) vapor at 25°C. For a 1 M boiling HCl solution, the HCl-vapor fractionation was ~9‰. The difference is probably related to the degree of dissociation in the acid, with HCl dissolved in water for the highly acidic solutions, and dissociated H3O+ and Cl- for lower concentrations. The HCl volatilization experiments are in contrast to earlier vapor-liquid experiments in NaCl-H2O system, where fractionation was

  4. The adjuvant use of stromal vascular fraction and platelet-rich fibrin for autologous adipose tissue transplantation.

    PubMed

    Liu, Bin; Tan, Xin-Ying; Liu, Yan-Pu; Xu, Xiao-Fang; Li, Long; Xu, Hai-Yan; An, Ran; Chen, Fa-Ming

    2013-01-01

    Autologous adipose transplantation is rapidly gaining popularity for the restoration of soft tissue defects and lipoatrophy as well as for aesthetic improvements (e.g., facial reconstruction and rejuvenation). However, the current technique is crude that suffers from serious demerits, particularly the long-term unpredictability of volume maintenance due to resorption of the grafted adipose tissue and limited adipogenesis. We hypothesized that the adjuvant use of patient-derived adipose stromal vascular fraction (SVF) and platelet-rich fibrin (PRF) may enhance the overall outcome of autologous fat grafting in plastic and reconstructive surgery. Autologous SVF, with a mean cell number of (4.8±3.79)×10⁷ cells/mL and a mean cell viability of 71.8%, and autologous PRF, with sustained release of multiple angiogenic growth factors, were created before surgical use. The following adipose tissue implants were injected subcutaneously into a rabbit ear's auricula according to the following study design: 2 mL adipose granules and 0.2 mL normal saline solution (AG+NS group), 2 mL adipose granules and 0.2 mL SVF (AG+SVF group), 2 mL adipose granules and 0.2 mL PRF (AG+PRF group), or 2 mL adipose granules combined with 0.1 mL SVF and 0.1 mL PRF (AG+SVF+PRF group). Histological examinations showed that the implanted adipose granules were well engrafted in the AG+SVF+PRF group, with a higher microvessel density 4 weeks postimplantation compared with the other three groups (p<0.01). Twenty-four weeks postimplantation, the resorption rates of implanted tissue in each group were 49.39%±9.47%, 27.25%±4.37%, 36.41%±8.47%, and 17.37%±6.22%, respectively, and were significantly different (p<0.01). The results demonstrated that the efficacy of adipose tissue implantation can be enhanced by using autologous PRF and SVF as therapeutic adjuvants, offering a clinically translatable strategy for soft tissue augmentation and reconstruction.

  5. Intracellular Cadmium Isotope Fractionation

    NASA Astrophysics Data System (ADS)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  6. Chromatographic methods of fractionation.

    PubMed

    Friesen, A D

    1987-01-01

    Chromatography's functional versatility, separation efficiency, gentle non-denaturing separating process and ease of automation and scale-up make it attractive for industrial scale protein purification. The Winnipeg Rh Institute's new Plasma Fractionation facility is an example of the use of chromatography for the large scale purification of plasma protein fractions. The fractionation facility has a capacity to process 800 litres of plasma per batch into blood clotting factor VIII and IX, albumin and intravenous immune serum globulin (i.v. ISG). Albumin and i.v. ISG are purified using ion exchange columns of DEAE-Sepharose (230 litre size), DEAE-Biogel (150 litre size) and CM-Sepharose (150 litre size). The chromatographic process is automated using a Modicon 584 Programmable Logic Controller to regulate valves, pumps and sensors which control plasma flow during fractionation. The stainless steel tanks and piping are automatically cleaned-in-place. The high degree of automation and cleaning provides efficient operation and sanitary processing. Chromatographic methods (DEAE-Sepharose and metal chelation) are also being used at the pilot scale to purify the human blood products superoxide dismutase and hemoglobin from outdated red blood cells. Characterization of the protein fractions produced by chromatography has shown them to be of equal or higher quality than fractions produced by other techniques.

  7. Oxygen isotope fractionation in phosphates: the role of dissolved complex anions in isotope exchange.

    PubMed

    Zheng, Yong-Fei

    2016-01-01

    Oxygen isotope fractionation factors for phosphates were calculated by means of the increment method. The results suggest that Ag3PO4 and BiPO4 are enriched in (18)O relative to AgPO4, and the three phosphates are consistently depleted in (18)O relative to Ba3[PO4]2; fluorapatite and chlorapatite exhibit a similar behaviour of oxygen isotope fractionation with consistent enrichment of (18)O relative to hydroxyapatite. The valence, radii and coordination of metal cations play a quantitative role in dictating the (18)O/(16)O partitioning in these phosphates of different compositions. The calculated fractionation factors for the Ag3PO4-H2O system are in agreement with experimental determinations derived from enzyme-catalysed isotope exchange between dissolved inorganic phosphate and water at the longest reaction durations at low temperatures. This demonstrates that the precipitated Ag3PO4 has completely captured the oxygen isotope fractionation in the dissolved inorganic phosphate. The calculated fractionation factors for the F/Cl-apatite-water systems are in agreement with the enzyme-catalysed experimental fractionations for the dissolved phosphate-water system at the longest reaction durations but larger than fractionations derived from bacteria-facilitated exchange and inorganic precipitation experiments as well as natural observations. For the experimental calibrations of oxygen isotope fractionation involving the precipitation of dissolved phosphate species from aqueous solutions, the fractionation between precipitate and water is primarily dictated by the isotope equilibration between the dissolved complex anions and water prior to the precipitation. Therefore, the present results provide a quantitative means to interpret the temperature dependence of oxygen isotope fractionation in inorganic and biogenic phosphates.

  8. Fire-through Ag contact formation for crystalline Si solar cells using single-step inkjet printing.

    PubMed

    Kim, Hyun-Gang; Cho, Sung-Bin; Chung, Bo-Mook; Huh, Joo-Youl; Yoon, Sam S

    2012-04-01

    Inkjet-printed Ag metallization is a promising method of forming front-side contacts on Si solar cells due to its non-contact printing nature and fine grid resolution. However, conventional Ag inks are unable to punch through the SiN(x) anti-reflection coating (ARC) layer on emitter Si surfaces. In this study, a novel formulation of Ag ink is examined for the formation of fire-through contacts on a SiN(x)-coated Si substrate using the single-step printing of Ag ink, followed by rapid thermal annealing at 800 degrees C. In order to formulate Ag inks with fire-through contact formation capabilities, a liquid etching agent was first formulated by dissolving metal nitrates in an organic solvent and then mixing the resulting solution with a commercial Ag nanoparticle ink at various volume ratios. During the firing process, the dissolved metal nitrates decomposed into metal oxides and acted in a similar manner to the glass frit contained in Ag pastes for screen-printed Ag metallization. The newly formulated ink with a 1 wt% loading ratio of metal oxides to Ag formed finely distributed Ag crystallites on the Si substrate after firing at 800 degrees C for 1 min.

  9. Synthesis of Ag(2) S-Ag nanoprisms and their use as DNA hybridization probes.

    PubMed

    Liu, Bing; Ma, Zhanfang

    2011-06-01

    A simple synthetic route to prepare Ag(2) S-Ag nanoprisms consists of the facile addition of Na(2) S to a solution of triangular Ag nanoprisms. The resulting Ag(2) S-Ag nanoparticles are more stable in solution than the original Ag nanoprisms, and two surface plasmon resonance (SPR) bands of the original Ag nanoprisms still remain. In addition, the SPR bands of the Ag(2) S-Ag nanoprisms are tunable over a wide range. The Ag(2) S-Ag nanoprisms can be directly bioconjugated via well-established stable Ag(2) S surface chemistry with readily available sulfur coupling agents. The nanoprisms are used in the hybridization of functionalized oligonucleotides, and show promise as probes for future biosensing applications. PMID:21538868

  10. soil organic matter fractionation

    NASA Astrophysics Data System (ADS)

    Osat, Maryam; Heidari, Ahmad

    2010-05-01

    Carbon is essential for plant growth, due to its effects on other soil properties like aggregation. Knowledge of dynamics of organic matter in different locations in the soil matrix can provide valuable information which affects carbon sequestration and soil the other soil properties. Extraction of soil organic matter (SOM) fractions has been a long standing approach to elucidating the roles of soil organic matter in soil processes. Several kind fractionation methods are used and all provide information on soil organic matter function. Physical fractionation capture the effects on SOM dynamics of the spatial arrangement of primary and secondary organomineral particles in soil while chemical fractionation can not consider the spatial arrangement but their organic fractions are suitable for advanced chemical characterization. Three method of physical separation of soil have been used, sieving, sedimentation and densitometry. The distribution of organic matter within physical fractions of the soil can be assessed by sieving. Sieving separates soil particles based strictly on size. The study area is located on north central Iran, between 35° 41'- 36° 01' N and 50° 42'- 51° 14' E. Mean annual precipitation about 243.8 mm and mean annual air temperature is about 14.95 °C. The soil moisture and temperature regime vary between aridic-thermic in lower altitudes to xeric-mesic in upper altitudes. More than 36 surface soil samples (0-20 cm) were collected according to land-use map units. After preliminary analyzing of samples 10 samples were selected for further analyses in five size fractions and three different time intervals in September, January and April 2008. Fractionation carried out by dry sieving in five classes, 1-2 mm, 0.5-1 mm, 270 μm-0.5mm, 53-270 μm and <53 μm. Organic matter and C/N ratio were determined for all fractions at different time intervals. Chemical fractionation of organic matter also carried out according to Tan (2003), also Mineralogical

  11. Fractional Noether Theorem Based on Extended Exponentially Fractional Integral

    NASA Astrophysics Data System (ADS)

    Long, Zi-Xuan; Zhang, Yi

    2013-10-01

    Based on the new type of fractional integral definition, namely extended exponentially fractional integral introduced by EI-Nabulsi, we study the fractional Noether symmetries and conserved quantities for both holonomic system and nonholonomic system. First, the fractional variational problem under the sense of extended exponentially fractional integral is established, the fractional d'Alembert-Lagrange principle is deduced, then the fractional Euler-Lagrange equations of holonomic system and the fractional Routh equations of nonholonomic system are given; secondly, the invariance of fractional Hamilton action under infinitesimal transformations of group is also discussed, the corresponding definitions and criteria of fractional Noether symmetric transformations and quasi-symmetric transformations are established; finally, the fractional Noether theorems for both holonomic system and nonholonomic system are explored. What's more, the relationship between the fractional Noether symmetry and conserved quantity are revealed.

  12. Stable silver isotope fractionation in the natural transformation process of silver nanoparticles.

    PubMed

    Lu, Dawei; Liu, Qian; Zhang, Tuoya; Cai, Yong; Yin, Yongguang; Jiang, Guibin

    2016-08-01

    Nanoparticles in the environment can form by natural processes or be released due to human activities. Owing to limited analytical methods, the behaviour of nanoparticles in the natural environment is poorly understood and until now they have only been described by the variations in the nanoparticle size or the concentration of the element of interest. Here we show that by using inductively coupled plasma mass spectrometry to measure silver (Ag) isotope ratios it is possible to understand the transformation processes of silver nanoparticles (AgNPs) in the environment. We found that the formation and dissolution of AgNPs under natural conditions caused significant variations in the ratio of natural Ag isotopes ((107)Ag and (109)Ag) with an isotopic enrichment factor (ε) up to 0.86‰. Furthermore, we show that engineered AgNPs have distinctly different isotope fractionation effects to their naturally formed counterparts. Further studies will be needed to understand whether isotope analysis can be used to reveal the sources of AgNPs in the environment.

  13. Stable silver isotope fractionation in the natural transformation process of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Lu, Dawei; Liu, Qian; Zhang, Tuoya; Cai, Yong; Yin, Yongguang; Jiang, Guibin

    2016-08-01

    Nanoparticles in the environment can form by natural processes or be released due to human activities. Owing to limited analytical methods, the behaviour of nanoparticles in the natural environment is poorly understood and until now they have only been described by the variations in the nanoparticle size or the concentration of the element of interest. Here we show that by using inductively coupled plasma mass spectrometry to measure silver (Ag) isotope ratios it is possible to understand the transformation processes of silver nanoparticles (AgNPs) in the environment. We found that the formation and dissolution of AgNPs under natural conditions caused significant variations in the ratio of natural Ag isotopes (107Ag and 109Ag) with an isotopic enrichment factor (ε) up to 0.86‰. Furthermore, we show that engineered AgNPs have distinctly different isotope fractionation effects to their naturally formed counterparts. Further studies will be needed to understand whether isotope analysis can be used to reveal the sources of AgNPs in the environment.

  14. Study of the oxygen transport through Ag (110), Ag (poly), and Ag 2.0 Zr

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Wu, D.; Davidson, M. R.; Hoflund, Gar B.

    1992-01-01

    The transport of oxygen through high-purity membranes of Ag (110), Ag (poly), Ag (nano), and Ag 2.0 Zr has been studied by an ultrahigh vacuum permeation method over the temperature range of 400-800 C. The data show that there are substantial deviations from ordinary diffusion-controlled transport. A surface limitation has been confirmed by glow-discharge studies where the upstream O2 supply has been partially converted to atoms, which, for the same temperature and pressure, gave rise to over an order of magnitude increase in transport flux. Further, the addition of 2.0 wt percent Zr to the Ag has provided increased dissociative adsorption rates, which, in turn, increased the transport flux by a factor of 2. It was also observed that below a temperature of 630 C, the diffusivity exhibits an increase in activation energy of over 4 kcal/mol, which has been attributed to trapping of the atomic oxygen and/or kinetic barriers at the surface and subsurface of the vacuum interface. Above 630 C, the activation barrier decreases to the accepted value of about 11 kcal/mol for Ag (poly), consistent with zero concentration at the vacuum interface.

  15. High Volume Fraction Carbon Nanotube Composites for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Siochi, E. J.; Kim, J.-W.; Sauti, G.; Cano, R. J.; Wincheski, R. A.; Ratcliffe, J. G.; Czabaj, M.

    2016-01-01

    Reported mechanical properties of carbon nanotubes (CNTs) at the nanoscale suggest their potential to enable significantly lighter structures of interest for space applications. However, their utility depends on the retention of these properties in bulk material formats that permit practical fabrication of large structures. This presentation summarizes recent progress made to produce carbon nanotube composites with specific tensile properties that begin to rival those of carbon fiber reinforced polymer composites. CNT content in these nanocomposites was greater than 70% by weight. Tested nanocomposite specimens were fabricated from kilometers or tens of square meters of CNT, depending on the starting material format. Processing methods to yield these results, and characterization and testing to evaluate the performance of these composites will be discussed. The final objective is the demonstration of a CNT composite overwrapped pressure vessel to be flight tested in the Fall of 2016.

  16. High Volume Fraction Carbon Nanotube Composites for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Siochi, Emilie J.; Kim, Jae-Woo; Sauti, Godfrey; Cano, Roberto J.; Wincheski, Russell A.; Ratcliffe, James G.; Czabaj, Michael; Jensen, Benjamin D.; Wise, Kristopher E.

    2015-01-01

    Reported nanoscale mechanical properties of carbon nanotubes (CNTs) suggest that their use may enable the fabrication of significantly lighter structures for use in space applications. To be useful in the fabrication of large structures, however, their attractive nanoscale properties must be retained as they are scaled up to bulk materials and converted into practically useful forms. Advances in CNT production have significantly increased the quantities available for use in manufacturing processes, but challenges remain with the retention of nanoscale properties in larger assemblies of CNTs. This work summarizes recent progress in producing carbon nanotube composites with tensile properties approaching those of carbon fiber reinforced polymer composites. These advances were achieved in nanocomposites with CNT content of 70% by weight. The processing methods explored to yield these CNT composite properties will be discussed, as will the characterization and test methods that were developed to provide insight into the factors that contribute to the enhanced tensile properties. Technology maturation was guided by parallel advancements in computational modeling tools that aided in the interpretation of experimental data.

  17. Laser Doppler Velocimetry and full-field soot volume fraction

    NASA Technical Reports Server (NTRS)

    Greenberg, Paul S.

    1995-01-01

    Since its introduction in the mid-sixties, Laser Doppler Velocimetry (LDV) has become one of the most widely used methods for the measurement of flows. Its remote and essentially non-intrusive nature provides an invaluable tool for a variety of difficult measurement situations which would be otherwise inaccessible. The high spatial resolution and rapid temporal response afforded by this technique are well suited to the determination of spatial and temporal details of flow fields, as well as characterization of turbulence. Advances in the understanding of the properties of LDV signals, accompanied by technological advances in coherent laser sources, detectors of high sensitivity and low noise, optical fabrication techniques and high-speed digital signal processing architectures have resulted in systems of increased accuracy and flexibility. As will be shown, recent progress in solid-state lasers and photo-detectors has been beneficial insofar as the compatibility of this method with the unique and severe constraints inherent in microgravity combustion science experiments.

  18. Water dynamics in different biochar fractions.

    PubMed

    Conte, Pellegrino; Nestle, Nikolaus

    2015-09-01

    Biochar is a carbonaceous porous material deliberately applied to soil to improve its fertility. The mechanisms through which biochar acts on fertility are still poorly understood. The effect of biochar texture size on water dynamics was investigated here in order to provide information to address future research on nutrient mobility towards plant roots as biochar is applied as soil amendment. A poplar biochar has been stainless steel fractionated in three different textured fractions (1.0-2.0 mm, 0.3-1.0 mm and <0.3 mm, respectively). Water-saturated fractions were analyzed by fast field cycling (FFC) NMR relaxometry. Results proved that 3D exchange between bound and bulk water predominantly occurred in the coarsest fraction. However, as porosity decreased, water motion was mainly associated to a restricted 2D diffusion among the surface-site pores and the bulk-site ones. The X-ray μ-CT imaging analyses on the dry fractions revealed the lowest surface/volume ratio for the coarsest fraction, thereby corroborating the 3D water exchange mechanism hypothesized by FFC NMR relaxometry. However, multi-micrometer porosity was evidenced in all the samples. The latter finding suggested that the 3D exchange mechanism cannot even be neglected in the finest fraction as previously excluded only on the basis of NMR relaxometry results. X-ray μ-CT imaging showed heterogeneous distribution of inorganic materials inside all the fractions. The mineral components may contribute to the water relaxation mechanisms by FFC NMR relaxometry. Further studies are needed to understand the role of the inorganic particles on water dynamics. PMID:25594163

  19. Effect of Aging Treatment on Fatigue Behavior of an Al-Cu-Mg-Ag Alloy

    NASA Astrophysics Data System (ADS)

    Burba, M. E.; Caton, M. J.; Jha, S. K.; Szczepanski, C. J.

    2013-11-01

    An investigation of the fatigue properties of an Al-Cu-Mg-Ag alloy with two different heat treatments—peak aged (T6), and peak aged interrupted (T6I4)—has been conducted. While the strength levels resulting from the two heat treatments were similar, the main difference between the microstructures was that the peak aged interrupted material contained a higher volume fraction of the θ' precipitates. This study specifically focused on the effects of these treatments on the fatigue lifetime distribution, and the role of crack initiation vs the small crack growth behavior. Several total fatigue lifetime tests were completed at room temperature and at a given stress level to characterize the distribution in fatigue lifetimes. Fatigue results indicate that there is almost no difference in the mean lifetime for either heat treatment, but there is a significant difference in the minimum lifetimes, where the peak aged condition exhibited a higher propensity for life-limiting failure mechanisms. The small crack growth behavior of the two aging treatments was studied both at room temperature and elevated temperature by means of a standard acetate replication method. The small crack growth rates at both temperatures were largely unaffected by the different aging treatments. Based on the given number of tests, results suggest that the life-limiting fatigue failures of the two aging treatments are primarily governed by different crack initiation mechanisms due to the differences seen in the density of θ' precipitates.

  20. Role of polarity fractions of effluent organic matter in binding and toxicity of silver and copper.

    PubMed

    Yoo, Jisu; Shim, Taeyong; Hur, Jin; Jung, Jinho

    2016-11-01

    This study evaluates the effect of the physicochemical properties of effluent organic matter (EfOM) from industrial and sewage wastewater treatment plants (WWTPs) on the binding and toxicity of Ag and Cu. EfOM was isolated into hydrophobic, transphilic, and hydrophilic fractions depending on its polarity, and was characterized by elemental, specific ultraviolet absorbance, and fluorescence excitation-emission matrix analyses. Our results suggest that the EfOM consists of microbially derived non-humic substances that have lower aromaticity than the Suwannee River natural organic matter (SR-NOM). The Freundlich model was better at explaining the binding of Ag and Cu onto both SR-NOM and EfOM than the Langmuir model. In particular, the hydrophilic fractions of sewage EfOM showed higher binding capacities and affinities for Ag and Cu than the corresponding hydrophobic fractions, resulting in better reduction of the acute toxicity of Ag and Cu towards Daphnia magna. However, in the case of both SR-NOM and industrial EfOM, the hydrophobic fractions were more efficient at reducing metal toxicity. These findings suggest that the EfOM has different physicochemical properties compared with NOM and that the binding and toxicity of heavy metals are largely dependent on the polarity fractions of EfOM. PMID:27318731

  1. Pd-Ag chronology of volatile depletion, crystallization and shock in the Muonionalusta IVA iron meteorite and implications for its parent body

    NASA Astrophysics Data System (ADS)

    Horan, M. F.; Carlson, R. W.; Blichert-Toft, J.

    2012-10-01

    Muonionalusta, a Group IVA iron meteorite, was analyzed for its 107Pd-107Ag isotope systematics by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in order to better constrain the initial Solar System abundance of 107Pd and to provide high resolution chronology of the evolution of its parent body. Six metal samples from Muonionalusta yield Ag abundances between 0.1012 and 1.461 ng/g, 107Ag/109Ag between 1.131 and 1.805, with 108Pd/109Ag ratios of 2201 to 52,300. The metal Pd/Ag and Ag isotopic data are correlated with a slope corresponding to a 107Pd/108Pd of (2.15±0.30)×10-5. If the Pd-Ag and Pb-Pb isotope systems closed at the same time in Muonionalusta, i.e., 2-3 Ma after CAI formation, then an initial Solar System ratio of 107Pd/108Pd=(2.8±0.5)×10-5 can be inferred. One troilite sample contains 8.478 ng/g Ag and has a 107Ag/109Ag ratio of 1.0833; its Pd concentration is 205.2 ng/g corresponding to a low 108Pd/109Ag of 13.56. The Pd-Ag results for this troilite plot near the extrapolation of the line passing through the metal points and define an initial 107Ag/109Ag that is substantially higher than chondritic, indicating that Muonionalusta formed from a precursor with high Pd/Ag. Pd and Ag concentrations in Muonionalusta metal suggest fractional crystallization from a source having Pd/Ag>4500, but the initial Ag isotopic composition for Muonionalusta troilite limits the duration of the high Pd/Ag to an interval of ≤0.6 Ma before cooling to closure of the Pd-Ag system. This result suggests that depletion of Ag and other volatile elements occurred shortly before accretion and cooling of the IVA parent body, and may have been associated with violent disruption of a progenitor to the IVA parent. Another troilite sample, its chromite inclusions and adjacent metal were isotopically homogenized locally after 107Pd had decayed, possibly by a later episode of shock >50 Ma after Solar System formation.

  2. Fractional Brownian motion and motion governed by the fractional Langevin equation in confined geometries.

    PubMed

    Jeon, Jae-Hyung; Metzler, Ralf

    2010-02-01

    Motivated by subdiffusive motion of biomolecules observed in living cells, we study the stochastic properties of a non-Brownian particle whose motion is governed by either fractional Brownian motion or the fractional Langevin equation and restricted to a finite domain. We investigate by analytic calculations and simulations how time-averaged observables (e.g., the time-averaged mean-squared displacement and displacement correlation) are affected by spatial confinement and dimensionality. In particular, we study the degree of weak ergodicity breaking and scatter between different single trajectories for this confined motion in the subdiffusive domain. The general trend is that deviations from ergodicity are decreased with decreasing size of the movement volume and with increasing dimensionality. We define the displacement correlation function and find that this quantity shows distinct features for fractional Brownian motion, fractional Langevin equation, and continuous time subdiffusion, such that it appears an efficient measure to distinguish these different processes based on single-particle trajectory data.

  3. Tyrphostin AG 556 improves survival and reduces multiorgan failure in canine Escherichia coli peritonitis.

    PubMed Central

    Sevransky, J E; Shaked, G; Novogrodsky, A; Levitzki, A; Gazit, A; Hoffman, A; Elin, R J; Quezado, Z M; Freeman, B D; Eichacker, P Q; Danner, R L; Banks, S M; Bacher, J; Thomas, M L; Natanson, C

    1997-01-01

    Tyrosine kinase-dependent cell signaling is postulated to be a pivotal control point in inflammatory responses initiated by bacterial products and TNF. Using a canine model of gram-negative septic shock, we investigated the effect of tyrosine kinase inhibitors (tyrphostins) on survival. Animals were infected intraperitoneally with Escherichia coli 0111: B4, and then, in a randomized, blinded fashion, were treated immediately with one of two tyrphostins, AG 556 (n = 40) or AG 126 (n = 10), or with control (n = 50), and followed for 28 d or until death. All animals received supplemental oxygen, fluids, and antibiotics. Tyrphostin AG 556 improved survival times when compared to controls (P = 0.05). During the first 48 h after infection, AG 556 also improved mean arterial pressure, left ventricular ejection fraction, cardiac output, oxygen delivery, and alveolar-arterial oxygen gradient compared to controls (all P < or = 0.05). These improvements in organ injury were significantly predictive of survival. Treatment with AG 556 had no effect on clearance of endotoxin or bacteria from the blood (both P = NS); however, AG 556 did significantly lower serum TNF levels (P = 0.03). These data are consistent with the conclusion that AG 556 prevented cytokine-induced multiorgan failure and death during septic shock by inhibiting cell-signaling pathways without impairing host defenses as determined by clearance of bacteria and endotoxin. PMID:9109441

  4. FRACTIONAL CRYSTALLIZATION FEED ENVELOPE

    SciTech Connect

    HERTING DL

    2008-03-19

    Laboratory work was completed on a set of evaporation tests designed to establish a feed envelope for the fractional crystallization process. The feed envelope defines chemical concentration limits within which the process can be operated successfully. All 38 runs in the half-factorial design matrix were completed successfully, based on the qualitative definition of success. There is no feed composition likely to be derived from saltcake dissolution that would cause the fractional crystallization process to not meet acceptable performance requirements. However, some compositions clearly would provide more successful operation than other compositions.

  5. Abundances of Ag and Cu in mantle peridotites and the implications for the behavior of chalcophile elements in the mantle

    NASA Astrophysics Data System (ADS)

    Wang, Zaicong; Becker, Harry

    2015-07-01

    Silver abundances in mantle peridotites and the behavior of Ag during high temperature mantle processes have received little attention and, as a consequence, the abundance of Ag in the bulk silicate Earth (BSE) has been poorly constrained. In order to better understand the processes that fractionate Ag and other chalcophile elements in the mantle, abundances of Ag and Cu in mantle peridotites from different geological settings (n = 68) have been obtained by isotope dilution ICP-MS methods. In peridotite tectonites and in a few suites of peridotite xenoliths which display evidence for variable extents of melt depletion and refertilization by silicate melts, Ag and Cu abundances show positive correlations with moderately incompatible elements such as S, Se, Te and Au. The mean Cu/Ag in fertile peridotites (3500 ± 1200, 1s, n = 38) is indistinguishable from the mean Cu/Ag of mid ocean ridge basalts (MORB, 3600 ± 400, 1s, n = 338) and MORB sulfide droplets. The constant mean Cu/Ag ratios indicate similar behavior of Ag and Cu during partial melting of the mantle, refertilization and magmatic fractionation, and thus should be representative of the Earth's upper mantle. The systematic fractionation of Cu, Ag, Au, S, Se and Te in peridotites and basalts is consistent with sulfide melt-silicate melt partitioning with apparent partition coefficients of platinum group elements (PGE) > Au ⩾ Te > Cu ≈ Ag > Se ⩾ S. Because of the effects of secondary processes, the abundances of chalcophile elements, notably S, Se, but also Cu and the PGE in many peridotite xenoliths are variable and lower than in peridotite massifs. Refertilization of peridotite may change abundances of chalcophile and lithophile elements in peridotite massifs, however, this seems to mostly occur in a systematic way. Correlations with lithophile and chalcophile elements and the overlapping mean Cu/Ag ratios of peridotites and ocean ridge basalts are used to constrain abundances of Ag and Cu in the BSE

  6. AGS slow extracted beam improvement

    SciTech Connect

    Marneris, I.; Danowski, G.; Sandberg, J.; Soukas, A.

    1997-07-01

    The Brookhaven AGS is a strong focusing accelerator which is used to accelerate protons and various heavy ion species to an equivalent proton energy of 29 GeV. Since the late 1960`s it has been serving high energy physics (HEP - proton beam) users of both slow and fast extracted beams. The AGS fixed target program presently uses primary proton and heavy ion beams (HIP) in slowly extracted fashion over spill lengths of 1.5 to 4.0 seconds. Extraction is accomplished by flattoping the main and extraction magnets and exciting a third integer resonance in the AGS. Over the long spill times, control of the subharmonic amplitude components up to a frequency of 1 kilohertz is very crucial. One of the most critical contributions to spill modulation is due to the AGS MMPS. An active filter was developed to reduce these frequencies and it`s operation is described in a previous paper. However there are still frequency components in the 60-720 Hz sub-harmonic ripple range, modulating the spill structure due to extraction power supplies and any remaining structures on the AGS MMPS. A recent scheme is being developed to use the existing tune-trim control horizontal quadrupole magnets and power supply to further reduce these troublesome noise sources. Feedback from an external beam sensor and overcoming the limitations of the quadrupole system by lead/lag compensation techniques will be described.

  7. HBsAg positivity during pregnancy and adverse maternal outcomes: a retrospective cohort analysis.

    PubMed

    Tan, J; Liu, X; Mao, X; Yu, J; Chen, M; Li, Y; Sun, X

    2016-10-01

    Hepatitis B virus infection characterized by HBsAg positivity during pregnancy is a well-recognized issue in developing countries, but the association between HBsAg positivity and adverse maternal outcomes remains uncertain. To examine the association between HBsAg positivity during pregnancy and adverse maternal outcomes, a retrospective cohort study was conducted in Sichuan province, China. Deliveries were recorded from six hospitals between 1 January 2009 and 31 December 2010. Pre-eclampsia, gestational diabetes mellitus (GDM), postpartum haemorrhage (PPH), intrahepatic cholestasis, Caesarean section and placenta previa were prespecified adverse maternal outcomes. We used two multivariate logistic regression models to assess the association between HBsAg positivity and adverse maternal outcomes. In total, 948 (4.2%) pregnant women were HBsAg positive from 22 374 deliveries. Pregnant women with positive HBsAg had higher risk of GDM (aOR1.41, 95%CI 1.15-1.74), PPH (1.44, 1.13-1.83), intrahepatic cholestasis (1.74, 1.40-2.16) and Caesarean section (1.24, 1.06-1.45). No statistical associations were found between HBsAg positivity and pre-eclampsia (1.36, 0.94-1.97), and placenta previa (1.21, 0.87-1.67). HBsAg positivity during pregnancy was associated with higher risk of multiple adverse maternal outcomes. Although the causality has yet to be established, efforts may be warranted in routine care, particularly in those with high risk for adverse maternal outcomes, given the volume population infected with HBsAg. Future studies are needed to establish causality and examine the impact of HBeAg on the adverse outcomes. PMID:27167604

  8. Momentum fractionation on superstrata

    DOE PAGES

    Bena, Iosif; Martinec, Emil; Turton, David; Warner, Nicholas P.

    2016-05-11

    Superstrata are bound states in string theory that carry D1, D5, and momentum charges, and whose supergravity descriptions are parameterized by arbitrary functions of (at least) two variables. In the D1-D5 CFT, typical three-charge states reside in highdegree twisted sectors, and their momentum charge is carried by modes that individually have fractional momentum. Understanding this momentum fractionation holographically is crucial for understanding typical black-hole microstates in this system. We use solution-generating techniques to add momentum to a multi-wound supertube and thereby construct the first examples of asymptotically-flat superstrata. The resulting supergravity solutions are horizonless and smooth up to well-understood orbifoldmore » singularities. Upon taking the AdS3 decoupling limit, our solutions are dual to CFT states with momentum fractionation. We give a precise proposal for these dual CFT states. Lastly, our construction establishes the very nontrivial fact that large classes of CFT states with momentum fractionation can be realized in the bulk as smooth horizonless supergravity solutions.« less

  9. Understanding Fraction Multiplication.

    ERIC Educational Resources Information Center

    Bezuk, Nadine S.; Armstrong, Barbara E.

    1992-01-01

    Presents five activities to help students construct meaning for multiplying fractions through real-world problem contexts, physical or pictorial models, the recognition of patterns, and the use of calculators. In the context of a garden plot, worksheets examine various aspects of parts of plots, patterns in plots, and a maximization problem.…

  10. Fractions through Fruit Salad.

    ERIC Educational Resources Information Center

    Lincoln, Lisa

    1987-01-01

    The mathematics concept of fractions was taught to a group of learning disabled, dyslexic, and multiply handicapped students (15-20 years old) by preparing a fruit salad. Enthusiastic student participation and enhanced knowledge illustrated the effectiveness of employing several sensory modes in learning activities. (CB)

  11. Field-Flow Fractionation.

    ERIC Educational Resources Information Center

    Caldwell, Karin D.

    1988-01-01

    Describes a technique for separating samples that range over 15 orders of magnitude in molecular weight. Discusses theory, apparatus, and sample preparation techniques. Lists several types of field-flow fractionation (FFF) and their uses: sedimentation FFF, thermal FFF, flow FFF, electrical FFF, and steric FFF. (ML)

  12. Avoidance of Fractions.

    ERIC Educational Resources Information Center

    Hart, Kathleen; Kerslake, Daphne

    The Concepts in Secondary Mathematics and Science (CSMS) and Strategies and Errors in Secondary Mathematics (SESM) research projects based at Chelsa College, England, have shown the marked reluctance of secondary school students to use fractions when solving mathematical problems, even though they have been taught the topic for a number of years.…

  13. Sweet Work with Fractions

    ERIC Educational Resources Information Center

    Vinogradova, Natalya; Blaine, Larry

    2013-01-01

    Almost everyone loves chocolate. However, the same cannot be said about fractions, which are loved by markedly fewer. Middle school students tend to view them with wary respect, but little affection. The authors attempt to sweeten the subject by describing a type of game involving division of chocolate bars. The activity they describe provides a…

  14. Videodisc Instruction in Fractions.

    ERIC Educational Resources Information Center

    Carnine, Douglas; And Others

    1987-01-01

    How laser videodisc technology can be used to improve mathematics instruction is described, with note of the development of a videodisc curriculum on mastering fractions. Relevant research is reviewed, as well as how teachers can use the technology. The instructional design is described, and field-testing and revision reported. (MNS)

  15. Momentum fractionation on superstrata

    NASA Astrophysics Data System (ADS)

    Bena, Iosif; Martinec, Emil; Turton, David; Warner, Nicholas P.

    2016-05-01

    Superstrata are bound states in string theory that carry D1, D5, and momentum charges, and whose supergravity descriptions are parameterized by arbitrary functions of (at least) two variables. In the D1-D5 CFT, typical three-charge states reside in high-degree twisted sectors, and their momentum charge is carried by modes that individually have fractional momentum. Understanding this momentum fractionation holographically is crucial for understanding typical black-hole microstates in this system. We use solution-generating techniques to add momentum to a multi-wound supertube and thereby construct the first examples of asymptotically-flat superstrata. The resulting supergravity solutions are horizonless and smooth up to well-understood orbifold singularities. Upon taking the AdS3 decoupling limit, our solutions are dual to CFT states with momentum fractionation. We give a precise proposal for these dual CFT states. Our construction establishes the very nontrivial fact that large classes of CFT states with momentum fractionation can be realized in the bulk as smooth horizonless supergravity solutions.

  16. Mechanism of high dielectric performance of polymer composites induced by BaTiO3-supporting Ag hybrid fillers

    NASA Astrophysics Data System (ADS)

    Fang, Fang; Yang, Wenhu; Yu, Shuhui; Luo, Suibin; Sun, Rong

    2014-03-01

    BaTiO3-supporting Ag hybrid particles (BT-Ag) with varied fraction of Ag were synthesized by reducing silver nitrate in the glycol solution containing BaTiO3 (BT) suspensions. The Ag nano particles with a size of about 20 nm were discretely grown on the surface of the BT. The dielectric performance of the composites containing the BT-Ag as fillers in the matrix of polyvinylidene fluoride (PVDF) was investigated. The relative permittivity (ɛr) of the BT-Ag/PVDF composites increased prominently with the increase of BT-Ag loading amount, and the typical conductive path of the conductor/polymer system was not observed even with a high loading of BT-Ag. The ɛr at 100 Hz for the three BT-(0.31, 0.49, 0.61)Ag/PVDF composites at room temperature were 283, 350, and 783, respectively. The ɛr of the composites was enhanced by more than 3 times compared with that of the composite containing untreated BT nanoparticles at frequencies over 1 kHz and the loss tangent (tan δ) was less than 0.1 which should be attributed to the low conductivity of the composites. Theoretical calculations based on the effective medium percolation theory model and series-parallel model suggested that the enhanced permittivity of BT-Ag/PVDF composites should arise from the ultrahigh permittivity of BT-Ag fillers, which was over 104 and associated with the content of Ag deposited on the surface of BT.

  17. Fractionated elution using the TEKCIS technetium-99m generator.

    PubMed

    Vigne, Jonathan; De Mil, Rémy; Peyronnet, Damien; Hecquard, Claudine; Agostini, Denis; Lemonnier, Françoise

    2016-06-01

    The TEKCIS technetium-99m (Tc) generator was designed to allow dry column shipment and automatized conception. A high Tc radioactive concentration is required in a subset of radiopharmacy procedures. Fractionated elution can be a useful tool to meet this requirement, especially when current elution is close to the generator expiration date. The aim of our study was to assess TEKCIS generator elution kinetics and to determine the optimal fractionated elution time to fit with procedures requiring the highest Tc radioactive concentration in clinical use. After duplicate elution at several predetermined elution times, the volume and activity of each eluate were measured. Two optimal time points were selected to perform fractionated elution and repeatability (n=34 and 33) assessed on TEKCIS generators calibrated at 6 or 8 GBq. The complete eluate volume (5 ml) was collected after 60 s of elution. A logarithmic equation was established between eluate volume (v, ml) from elapsed elution time (t, s): v=1.8335ln(t)-2.5965. Using the reciprocal equation, elution times required to obtain some commonly eluted volumes were calculated. Fractionated elutions during 15 and 20 s were selected and an average elution volume from 2.74 to 3.27 ml was collected, with an average elution yield of approximately 90 and 100%, respectively. Our work provides a simple and reliable methodology for the use of fractionated elution with the new TEKCIS generator.

  18. Photoelectron spectroscopy of AgCl, AgBr, and AgI vapors

    SciTech Connect

    Berkowitz, J.; Batson, C.H.; Goodman, G.L.

    1980-06-01

    He I photoelectron spectra of AgCl, AgBr and AgI vapors have been obtained which differ significantly from earlier work. In each instance, the characteristic features of the diatomic molecule are prominent. The spectral features separate into a valence region, predominantly halogen p-like, and a deeper region, predominantly of Ag 4d character. The latter is split by spin--orbit and ligand field interactions, which are parametrized from the experimental data. Relativistic calculations of the X/sub ..cap alpha../--DVM--SCC type have been performed for these species. At the transition state level, they agree very well with the experimental peak positions. Nonrelativistic calculations of this type have been performed for CuCl and cyclic Cu/sub 3/Cl/sub 3/. Unlike the AgX species, the CuCl and Cu/sub 3/Cl/sub 3/ exhibit strong mixing of metal d and halogen p orbitals for the uppermost occupied orbital, and other Cu 3d-like orbitals above the Cl 3p-like orbitals. It is suggested that the occurrence of Cu 3d orbitals in the valence region may play a role in the anomalous diagmagnetic signal and large conductivity changes of CuCl condensed from the vapor.

  19. Surface plasmon resonance in nanostructured Ag incorporated ZnS films

    SciTech Connect

    Chalana, S. R.; Mahadevan Pillai, V. P.; Ganesan, V.

    2015-10-15

    Silver incorporated zinc sulfide thin films are prepared by RF magnetron sputtering technique and the influence of silver incorporation on the structural, optical and luminescence properties is analyzed using techniques like grazing incidence X-Ray diffraction (GIXRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), micro-Raman spectroscopy, UV-Vis spectroscopy and laser photoluminescence spectroscopy. XRD analysis presents hexagonal wurtzite structure for the films. A reduction of crystallinity of the films is observed due to Ag incorporation. The Raman spectral analysis confirms the reduction of crystallinity and increase of strain due to the Ag incorporation. AFM analysis reveals a rough surface morphology for the undoped film and Ag incorporation makes the films uniform, dense and smooth. A blue shift of band gap energy with increase in Ag incorporation is observed due to quantum confinement effect. An absorption band (450-650 nm region) due to surface plasmon resonance of the Ag clusters present in the ZnS matrix is observed for the samples with higher Ag incorporation. The complex dielectric constant, loss factor and distribution of volume and surface energy loss of the ZnS thin films are calculated. Laser photoluminescence measurements gives an intense bluish green emission from the ZnS films and a quenching of the PL emission is observed which can be due to the metal plasmonic absorption and non-radiative energy transfer due to Ag incorporation.

  20. The AGS Booster control system

    SciTech Connect

    Frankel, R.; Auerbach, E.; Culwick, B.; Clifford, T.; Mandell, S.; Mariotti, R.; Salwen, C.; Schumburg, N.

    1988-01-01

    Although moderate in size, the Booster construction project requires a comprehensive control system. There are three operational modes: as a high intensity proton injector for the AGS, as a heavy ion accelerator and injector supporting a wide range of ions and as a polarized proton storage injector. These requirements are met using a workstation based extension of the existing AGS control system. Since the Booster is joining a complex of existing accelerators, the new system will be capable of supporting multiuser operational scenarios. A short discussion of this system is discussed in this paper.

  1. AG Draconis - a symbiotic mystery

    NASA Astrophysics Data System (ADS)

    Galis, R.; Hric, L.; Smelcer, L.

    2015-02-01

    Symbiotic system AG Draconis regularly undergoes quiescent and active stages which consist of the series of individual outbursts. The period analysis of new and historical photometric data, as well as radial velocities, confirmed the presence of the two periods. The longer one (~550 d) is related to the orbital motion and the shorter one (~355 d) could be due to pulsation of the cool component of AG Dra. In addition, the active stages change distinctively, but the outbursts are repeated with periods from 359 - 375 d.

  2. In situ study of defect migration kinetics in nanoporous Ag with enhanced radiation tolerance

    PubMed Central

    Sun, C.; Bufford, D.; Chen, Y.; Kirk, M. A.; Wang, Y. Q.; Li, M.; Wang, H.; Maloy, S. A.; Zhang, X.

    2014-01-01

    Defect sinks, such as grain boundaries and phase boundaries, have been widely accepted to improve the irradiation resistance of metallic materials. However, free surface, an ideal defect sink, has received little attention in bulk materials as surface-to-volume ratio is typically low. Here by using in situ Kr ion irradiation technique in a transmission electron microscope, we show that nanoporous (NP) Ag has enhanced radiation tolerance. Besides direct evidence of free surface induced frequent removal of various types of defect clusters, we determined, for the first time, the global and instantaneous diffusivity of defect clusters in both coarse-grained (CG) and NP Ag. Opposite to conventional wisdom, both types of diffusivities are lower in NP Ag. Such a surprise is largely related to the reduced interaction energy between isolated defect clusters in NP Ag. Determination of kinetics of defect clusters is essential to understand and model their migration and clustering in irradiated materials. PMID:24435181

  3. Label free detection of DNA on Au/ZnO/Ag hybrid structure based SERS substrate

    NASA Astrophysics Data System (ADS)

    Pal, Anil Kumar; Mohan, D. Bharathi

    2016-04-01

    Au/ZnO/Ag based SERS substrate was fabricated for the label free detection of DNA of Escherichia Coli bacteria. The SERS substrate was fabricated by growing ZnO nanorod arrays on thermally evaporated ultrathin Ag film of 5 nm thickness using hydrothermal process. Non-spherical like Au nanoparticles were decorated on ZnO nanorod arrays by sputtering technique with sputtering time of 45 sec. The surface of Au/ZnO/Ag was observed to be nearly superhydrophobic exhibiting the contact angle of 144 °. A low volume (5 µl) of aqueous solution of DNA of laboratory strain Escherichia Coli with very low concentration was adsorbed on fabricated SERS substrate by drop casting. The SERS detection of DNA molecules was achieved up to lower concentration of 10-8 M due to strong local electric field enhancement at the nanometer gap among Au nanoparticles and superhydrophobic nature of Au/ZnO/Ag surface.

  4. Quantum volume

    NASA Astrophysics Data System (ADS)

    Ryabov, V. A.

    2015-08-01

    Quantum systems in a mechanical embedding, the breathing mode of a small particles, optomechanical system, etc. are far not the full list of examples in which the volume exhibits quantum behavior. Traditional consideration suggests strain in small systems as a result of a collective movement of particles, rather than the dynamics of the volume as an independent variable. The aim of this work is to show that some problem here might be essentially simplified by introducing periodic boundary conditions. At this case, the volume is considered as the independent dynamical variable driven by the internal pressure. For this purpose, the concept of quantum volume based on Schrödinger’s equation in 𝕋3 manifold is proposed. It is used to explore several 1D model systems: An ensemble of free particles under external pressure, quantum manometer and a quantum breathing mode. In particular, the influence of the pressure of free particle on quantum oscillator is determined. It is shown also that correction to the spectrum of the breathing mode due to internal degrees of freedom is determined by the off-diagonal matrix elements of the quantum stress. The new treatment not using the “force” theorem is proposed for the quantum stress tensor. In the general case of flexible quantum 3D dynamics, quantum deformations of different type might be introduced similarly to monopole mode.

  5. Ag-Ag2S Hybrid Nanoprisms: Structural versus Plasmonic Evolution.

    PubMed

    Shahjamali, Mohammad M; Zhou, Yong; Zaraee, Negin; Xue, Can; Wu, Jinsong; Large, Nicolas; McGuirk, C Michael; Boey, Freddy; Dravid, Vinayak; Cui, Zhifeng; Schatz, George C; Mirkin, Chad A

    2016-05-24

    Recently, Ag-Ag2S hybrid nanostructures have attracted a great deal of attention due to their enhanced chemical and thermal stability, in addition to their morphology- and composition-dependent tunable local surface plasmon resonances. Although Ag-Ag2S nanostructures can be synthesized via sulfidation of as-prepared anisotropic Ag nanoparticles, this process is poorly understood, often leading to materials with anomalous compositions, sizes, and shapes and, consequently, optical properties. In this work, we use theory and experiment to investigate the structural and plasmonic evolution of Ag-Ag2S nanoprisms during the sulfidation of Ag precursors. The previously observed red-shifted extinction of the Ag-Ag2S hybrid nanoprism as sulfidation occurs contradicts theoretical predictions, indicating that the reaction does not just occur at the prism tips as previously speculated. Our experiments show that sulfidation can induce either blue or red shifts in the extinction of the dipole plasmon mode, depending on reaction conditions. By elucidating the correlation with the final structure and morphology of the synthesized Ag-Ag2S nanoprisms, we find that, depending on the reaction conditions, sulfidation occurs on the prism tips and/or the (111) surfaces, leading to a core(Ag)-anisotropic shell(Ag2S) prism nanostructure. Additionally, we demonstrate that the direction of the shift in the dipole plasmon is a function of the relative amounts of Ag2S at the prism tips and Ag2S shell thickness around the prism.

  6. Dependence of stability of metastable superconductors on copper fraction

    SciTech Connect

    Elrod, S. A.; Lue, J. W.; Miller, J. R.; Dresner, L.

    1980-12-01

    The stability of composite superconductors operating in the metastable regime depends upon such factors as matrix resistivity, cooled surface dimensions, fraction of critical current, and volume fraction of stabilizer. By assuming constant thermophysical properties, we developed analytic expressions for the energy and voltage of the minimum propagating zone (MPZ). With other factors held constant, these expressions have been used to predict composite superconductor stability as a function of copper fraction: lower copper fractions lead to higher MPZ energies. MPZ voltages have been measured for three NbTi/Cu composites having different copper fractions and different critical current densities for several magnetic fields and transport currents. Experimental MPZ voltages have been used to calculate an effective heat transfer coefficient, which is subsequently used to calculate the MPZ energy. The experimental MPZ energies support the theoretical expectation that lower copper fractions lead to higher stability in the metastable regime.

  7. An Introduction to Continued Fractions.

    ERIC Educational Resources Information Center

    Moore, Charles G.

    Provided is an introduction to the properties of continued fractions for the intellectually curious high school student. Among the topics included are (1) Expansion of Rational Numbers into Simple Continued Fractions, (2) Convergents, (3) Continued Fractions and Linear Diophantine Equations of the Type am + bn = c, (4) Continued Fractions and…

  8. Experimental status of the AGS Relativistic Heavy Ion Program

    SciTech Connect

    Sangster, T.C.

    1994-10-01

    The universal motivation for colliding large nuclei at relativistic energies is the expectation that a small volume of the primordial quark soup, generally referred to as the Quark-Gluon Plasma (QGP), can be created and studied. The QGP is formed via a phase transition caused by either the extreme baryon densities and/or the extreme temperatures achieved in the overlap zone of the two colliding nuclei. Experiments at the Brookhaven National Laboratory Alternating Gradient Synchrotron (AGS) using a beam of Si nuclei at 14.6 GeV per nucleon on various nuclear targets have been completed. These same experiments are now actively searching for signatures of QGP formation using a beam of Au nuclei at 11.7 GeV per nucleon. This paper briefly summarizes some of the key results from the Si beam program and the current status of the experimental Au beam program at the AGS.

  9. Radiation Dose-Volume Effects of Optic Nerves and Chiasm

    SciTech Connect

    Mayo, Charles; Martel, Mary K.; Marks, Lawrence B.; Flickinger, John; Nam, Jiho; Kirkpatrick, John

    2010-03-01

    Publications relating radiation toxicity of the optic nerves and chiasm to quantitative dose and dose-volume measures were reviewed. Few studies have adequate data for dose-volume outcome modeling. The risk of toxicity increased markedly at doses >60 Gy at {approx}1.8 Gy/fraction and at >12 Gy for single-fraction radiosurgery. The evidence is strong that radiation tolerance is increased with a reduction in the dose per fraction. Models of threshold tolerance were examined.

  10. Ag nanotubes and Ag/AgCl electrodes in nanoporous membranes

    NASA Astrophysics Data System (ADS)

    Davenport, Matthew; Healy, Ken; Siwy, Zuzanna S.

    2011-04-01

    Miniaturization of the entire experimental setup is a key requirement for widespread application of nanodevices. For nanopore biosensing, integrating electrodes onto the nanopore membrane and controlling the pore length is important for reducing the complexity and improving the sensitivity of the system. Here we present a method to achieve these goals, which relies on electroless plating to produce Ag nanotubes in track-etched polymer nanopore templates. By plating from one side only, we create a conductive nanotube that does not span the full length of the pore, and thus can act as a nanoelectrode located inside the nanopore. To give optimal electrochemical behavior for sensing, we coat the Ag nanotube with a layer of AgCl. We characterize the behavior of this nanoelectrode by measuring its current-voltage response and find that, in most cases, the response is asymmetric. The plated nanopores have initial diameters between 100 and 300 nm, thus a range suitable for detection of viruses.

  11. Photoreduction of Ag+ in Ag/Ag2S/Au memristor

    NASA Astrophysics Data System (ADS)

    Mou, N. I.; Tabib-Azar, M.

    2015-06-01

    Silver halides and chalcogenides are excellent memristor materials that have been extensively used in the past as photosensitive layers in photography. Here we examine the effect of illumination on the operating voltages and switching speed of Ag/Ag2S/Au memristors using a green laser (473-523 nm). Our results indicate that illumination decreases the average switching time from high to low resistance states by ∼19% and decreases the turn-off voltages dramatically from -0.8 V to -0.25 V that we attribute to the change in sulfur valency and a photo-induced change in its oxidation/reduction potential. Photo-induced reduction of silver in Ag2S may be used in three dimensional optical memories that can be electronically read and reset.

  12. Ag-Ag dispersive interaction and physical properties of Ag3Co(CN)6

    NASA Astrophysics Data System (ADS)

    Fang, Hong; Dove, Martin T.; Refson, Keith

    2014-08-01

    We report a density functional theory (DFT) study of Ag3Co(CN)6, a material noted for its colossal positive and negative thermal expansion, and its giant negative linear compressibility. Here, we explicitly include the dispersive interaction within the DFT calculation, and find that it is essential to reproduce the ground state, the high-pressure phase, and the phonons of this material, and hence essential to understand this material's remarkable physical properties. New exotic properties are predicted. These include heat enhancement of the negative linear compressibility, a large reduction in the coefficient of thermal expansion on compression with change of sign of the mode Grüneisen parameters under pressure, and large softening of the material on heating. Our results suggest that these are associated with the weak Ag-Ag dispersive interactions acting with an efficient hinging mechanism in the framework structure.

  13. A Computer-Interfaced Drop Counter as an Inexpensive Fraction Collector for Column Chromatography

    ERIC Educational Resources Information Center

    Nash, Barbara T.

    2008-01-01

    A computer-interfaced drop counter is described that serves as an inexpensive alternative to a fraction collector for column chromatography experiments. Undergraduate biochemistry laboratories frequently do not have the budget to purchase fraction collectors. Protocols that call for the manual measurement of fraction volumes as well as the manual…

  14. Laser-based synthesis of core Ag-shell AgI nanoparticles

    NASA Astrophysics Data System (ADS)

    Tan, Hua; Fan, Wai Yip

    2005-05-01

    A laser-controlled synthesis of silver iodide (AgI) nanoparticles with isolable AgI shell-Ag core stable intermediates is achieved via molecular iodine photodissociation in the presence of pure Ag nanoparticles dispersed in water. Ag nanoparticles were introduced into the solution containing sodium dodecylsulphate surfactants and iodine by ablating a piece of silver foil with a 532 nm pulsed Nd-YAG laser. Transmission electron microscopy images showed that different AgI shell-Ag core sizes could be achieved by controlling the photolysis of I 2 in solution. These nanoparticles were also found to catalyse an atom-economy Grignard-Barbier organic reaction.

  15. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO₃) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils.

    PubMed

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A M; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J

    2015-08-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value.

  16. AGS experiments: 1990, 1991, 1992. Ninth edition

    SciTech Connect

    Depken, J.C.

    1993-04-01

    This report contains a description of the following: AGS Experimental Area - High Energy Physics FY 1993 and Heavy Ion Physics FY 1993; Table of Beam Parameters and Fluxes; Experiment Schedule ``as run``; Proposed 1993 Schedule; A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Publications of AGS Experiments; and List of AGS Experimenters.

  17. Three mechanisms of ore re-mobilisation during amphibolite facies metamorphism at the Montauban Zn-Pb-Au-Ag deposit

    NASA Astrophysics Data System (ADS)

    Tomkins, Andrew G.

    2007-08-01

    The relative importance of mechanical re-mobilisation, hydrothermal dissolution and re-precipitation, and sulphide melting in controlling redistribution of metals during concurrent metamorphism and deformation is evaluated at the middle amphibolite facies Montauban deposit in Canada. As at many other deposits, ductile deformation was important in driving mechanical re-mobilisation of massive sulphides from limb regions into hinge regions of large-scale folds and is thus the most important for controlling the economics of Pb and Zn distribution. Two possible stages of hydrothermally driven re-mobilisation are discussed, each of which produces characteristically different alteration assemblages. Prograde hydrothermal re-mobilisation is driven by pyrite de-sulphidation and concurrent chlorite dehydration and is thus an internally driven process. At Montauban, the H2S-rich fluid generated through this process allowed re-mobilisation of gold into the wall rock, where it was deposited in response to sulphidation of Fe Mg silicates. Retrograde hydrothermal re-mobilisation is an externally driven process, whereby large volumes of fluids from outside the deposit may dissolve and re-precipitate metals, and cause hydration of silicate minerals. This second hydrothermally driven process is not recognised at Montauban. Sulphide melting occurred as temperatures neared the peak metamorphic conditions. Melting initiated in the massive sulphides through arsenopyrite breakdown, and a small volume of melt was subsequently re-mobilised into the wall rock. Trace element partitioning and fractional crystallisation of this melt generated a precious metal-rich fractionate, which remained mobile until well after peak metamorphism. Thus, prograde hydrothermal re-mobilisation and sulphide melting were the most important mechanisms for controlling the distribution of Au and Ag.

  18. Testing fractional action cosmology

    NASA Astrophysics Data System (ADS)

    Shchigolev, V. K.

    2016-08-01

    The present work deals with a combined test of the so-called Fractional Action Cosmology (FAC) on the example of a specific model obtained by the author earlier. In this model, the effective cosmological term is proportional to the Hubble parameter squared through the so-called kinematic induction. The reason of studying this cosmological model could be explained by its ability to describe two periods of accelerated expansion, that is in agreement with the recent observations and the cosmological inflation paradigm. First of all, we put our model through the theoretical tests, which gives a general conception of the influence of the model parameters on its behavior. Then, we obtain some restrictions on the principal parameters of the model, including the fractional index, by means of the observational data. Finally, the cosmography parameters and the observational data compared to the theoretical predictions are presented both analytically and graphically.

  19. [Fractionated P-bilirubins].

    PubMed

    Schou, C S; Mortensen, H

    1989-08-14

    A diazo-based dry film technique for the estimation of different bilirubins in plasma is now available. This procedure separates bilirubins from icteric sera into three separate fractions: bilirubin (unconjugated), bilirubin-glucuronides (mono + diglucuronide) and bilirubin-albumin. In newborns with prolonged jaundice classification of hyperbilirubinemia is of importance for choice of treatment. While binding of bilirubin and bilirubin-glucuronides to albumin is non covalent, reversible, bilirubin-albumin appears to be firmly associated with albumin by covalent bonds. This causes delayed clearance of this bilirubin fraction from plasma as the half-life of albumin is approximately 18 days. Hence the substance concentration of bilirubin-albumin will decrease at a slower rate than will bilirubin and bilirubin-glucuronide, despite hepatobiliary recovery. Bilirubin-albumin may therefore prove of value in the differentiation between different clinical entities with hyperbilirubinemia. PMID:2773134

  20. New Dry Fractionation Methods

    NASA Technical Reports Server (NTRS)

    McKay, David S.; Cooper, Bonnie L.

    2010-01-01

    This slide presentation describes new fractionation methods that are used to create dust that is respirable for testing the effects of inhalation of lunar dust in preparation for future manned lunar exploration. Because lunar dust is a very limited commodity, a method that does not result in loss of the material had to be developed. The dust separation system that is described incorporates some traditional methods, while preventing the dust from being contaminated or changed in reactivity properties while also limiting losses.

  1. Fractional Galilean symmetries

    NASA Astrophysics Data System (ADS)

    Hosseiny, Ali; Rouhani, Shahin

    2016-09-01

    We generalize the differential representation of the operators of the Galilean algebras to include fractional derivatives. As a result a whole new class of scale invariant Galilean algebras are obtained. The first member of this class has dynamical index z = 2 similar to the Schrödinger algebra. The second member of the class has dynamical index z = 3 / 2, which happens to be the dynamical index Kardar-Parisi-Zhang equation.

  2. Model Fractional Chern Insulators.

    PubMed

    Behrmann, Jörg; Liu, Zhao; Bergholtz, Emil J

    2016-05-27

    We devise local lattice models whose ground states are model fractional Chern insulators-Abelian and non-Abelian topologically ordered states characterized by exact ground state degeneracies at any finite size and infinite entanglement gaps. Most saliently, we construct exact parent Hamiltonians for two distinct families of bosonic lattice generalizations of the Z_{k} parafermion quantum Hall states: (i) color-entangled fractional Chern insulators at band filling fractions ν=k/(C+1) and (ii) nematic states at ν=k/2, where C is the Chern number of the lowest band. In spite of a fluctuating Berry curvature, our construction is partially frustration free: the ground states reside entirely within the lowest band and exactly minimize a local (k+1) body repulsion term by term. In addition to providing the first known models hosting intriguing states such as higher Chern number generalizations of the Fibonacci anyon quantum Hall states, the remarkable stability and finite-size properties make our models particularly well suited for the study of novel phenomena involving, e.g., twist defects and proximity induced superconductivity, as well as being a guide for designing experiments.

  3. Model Fractional Chern Insulators

    NASA Astrophysics Data System (ADS)

    Behrmann, Jörg; Liu, Zhao; Bergholtz, Emil J.

    2016-05-01

    We devise local lattice models whose ground states are model fractional Chern insulators—Abelian and non-Abelian topologically ordered states characterized by exact ground state degeneracies at any finite size and infinite entanglement gaps. Most saliently, we construct exact parent Hamiltonians for two distinct families of bosonic lattice generalizations of the Zk parafermion quantum Hall states: (i) color-entangled fractional Chern insulators at band filling fractions ν =k /(C +1 ) and (ii) nematic states at ν =k /2 , where C is the Chern number of the lowest band. In spite of a fluctuating Berry curvature, our construction is partially frustration free: the ground states reside entirely within the lowest band and exactly minimize a local (k +1 ) body repulsion term by term. In addition to providing the first known models hosting intriguing states such as higher Chern number generalizations of the Fibonacci anyon quantum Hall states, the remarkable stability and finite-size properties make our models particularly well suited for the study of novel phenomena involving, e.g., twist defects and proximity induced superconductivity, as well as being a guide for designing experiments.

  4. Model Fractional Chern Insulators.

    PubMed

    Behrmann, Jörg; Liu, Zhao; Bergholtz, Emil J

    2016-05-27

    We devise local lattice models whose ground states are model fractional Chern insulators-Abelian and non-Abelian topologically ordered states characterized by exact ground state degeneracies at any finite size and infinite entanglement gaps. Most saliently, we construct exact parent Hamiltonians for two distinct families of bosonic lattice generalizations of the Z_{k} parafermion quantum Hall states: (i) color-entangled fractional Chern insulators at band filling fractions ν=k/(C+1) and (ii) nematic states at ν=k/2, where C is the Chern number of the lowest band. In spite of a fluctuating Berry curvature, our construction is partially frustration free: the ground states reside entirely within the lowest band and exactly minimize a local (k+1) body repulsion term by term. In addition to providing the first known models hosting intriguing states such as higher Chern number generalizations of the Fibonacci anyon quantum Hall states, the remarkable stability and finite-size properties make our models particularly well suited for the study of novel phenomena involving, e.g., twist defects and proximity induced superconductivity, as well as being a guide for designing experiments. PMID:27284668

  5. An efficient photocatalyst for degradation of various organic dyes: Ag@Ag2MoO4-AgBr composite.

    PubMed

    Bai, Yu-Yang; Lu, Yi; Liu, Jin-Ku

    2016-04-15

    The Ag2MoO4-AgBr composite was prepared by a facile in-situ anion-exchange method, then the Ag nanoparticles were coated on this composite through photodeposition route to form a novel Ag@Ag2MoO4-AgBr composite. The in-situ Br(-) replacement in a crystal lattice node position of Ag2MoO4 crystal allows for overcoming the resistance of electron transition effectively. Meanwhile silver nano-particles on the surface of Ag@Ag2MoO4-AgBr composite could act as electron traps to intensify the photogeneration electron-hole separation and the subsequent transfer of the trapped electron to the adsorbed O2 as an electron acceptor. As an efficient visible light catalyst, the Ag@Ag2MoO4-AgBr composite exhibited superior photocatalytic activity for the degradation of various organic dyes. The experimental results demonstrated superior photocatalytic rate of Ag@Ag2MoO4-AgBr composite compared to pure AgBr and Ag2MoO4 crystals (37.6% and 348.4% enhancement respectively). The Ag@Ag2MoO4-AgBr composite cloud degraded Rhodamin B, bromophenol blue, and amino black 10b completed in 7min. PMID:26775100

  6. An efficient photocatalyst for degradation of various organic dyes: Ag@Ag2MoO4-AgBr composite.

    PubMed

    Bai, Yu-Yang; Lu, Yi; Liu, Jin-Ku

    2016-04-15

    The Ag2MoO4-AgBr composite was prepared by a facile in-situ anion-exchange method, then the Ag nanoparticles were coated on this composite through photodeposition route to form a novel Ag@Ag2MoO4-AgBr composite. The in-situ Br(-) replacement in a crystal lattice node position of Ag2MoO4 crystal allows for overcoming the resistance of electron transition effectively. Meanwhile silver nano-particles on the surface of Ag@Ag2MoO4-AgBr composite could act as electron traps to intensify the photogeneration electron-hole separation and the subsequent transfer of the trapped electron to the adsorbed O2 as an electron acceptor. As an efficient visible light catalyst, the Ag@Ag2MoO4-AgBr composite exhibited superior photocatalytic activity for the degradation of various organic dyes. The experimental results demonstrated superior photocatalytic rate of Ag@Ag2MoO4-AgBr composite compared to pure AgBr and Ag2MoO4 crystals (37.6% and 348.4% enhancement respectively). The Ag@Ag2MoO4-AgBr composite cloud degraded Rhodamin B, bromophenol blue, and amino black 10b completed in 7min.

  7. Treatability of organic fractions derived from secondary effluent by reverse osmosis membrane.

    PubMed

    Hu, J Y; Ong, S L; Shan, J H; Kang, J B; Ng, W J

    2003-11-01

    Dissolved organic matters (DOMs) from two batches of secondary effluent collected from a local water reclamation plant were fractionated using column chromatographic method with non-ionic resins XAD-8, AG MP-50 and IRA-96. Seven isolated fractions were obtained from the fractionation study and these fractions were quantified using DOC, UV(254) and SUVA values. The fractionation study revealed that the secondary effluent samples comprised about 47.3-60.6% of hydrophobic and 39.4-52.7% of hydrophilic solutes. The treatability of each isolated fraction was investigated by subjecting each fraction to reverse osmosis (RO) treatment individually. It was noted that RO process could achieve high DOC rejections for acid and neutral fractions (ranging from 80% to 98% removal) probably due to the negative charge of RO membrane. The results obtained also indicated that hydrophobicity of DOMs is significant in determining treatability of organic species by RO process. The performance of RO in terms of DOC rejection of un-fractionated secondary effluent was also investigated to assess possible effects of interactions among organic fractions on their treatability by RO process. It was noted that DOC rejection associated with the un-fractionated secondary effluent was generally higher (ranging from 2% to 45%) than the corresponding rejection obtained from each individual fraction isolated from the secondary effluent. This finding suggested there is a beneficial interaction among the fractions that in turn has contributed towards a better overall DOC rejection performance by RO treatment.

  8. AGS experiments: 1985, 1986, 1987

    SciTech Connect

    Depken, J.C.

    1987-01-01

    This report contains: Experimental areas layout, table of beam parameters and fluxes, experiment schedule ''as run,'' experiment long range schedule, a listing of experiments by number, two-page summaries of each experiment, also ordered by number, and publications of AGS experiments, 1982-1987.

  9. Correcting the AGS depolarizing resonances

    SciTech Connect

    Ratner, L.G.

    1986-01-01

    For the 1986 AGS run, the technique of correcting an imperfection resonance using a beat harmonic instead of the direct harmonic was applied and found to be useful in achieving a 22 GeV/c polarized beam. Both conventional and modified techniques are explained. (LEW)

  10. What Is Ag-Ed?

    ERIC Educational Resources Information Center

    Linley, Judy; Mylne, Lee

    1998-01-01

    Ag-Ed, an agricultural education project for upper elementary students, was held in conjunction with the Toowoomba Show in Queensland, Australia. Agriculture industry representatives provided 20 interactive agricultural presentations for class groups, which were supplemented with a teacher resource-package containing a directory and 13 sections of…

  11. AGS experiments, 1988, 1989, 1990

    SciTech Connect

    Depken, J.C.

    1991-04-01

    This report contains: experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; experiment long range schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS experiments; and list of experimenters.

  12. Extracts and Fractions from Edible Roots of Sechium edule (Jacq.) Sw. with Antihypertensive Activity

    PubMed Central

    Lombardo-Earl, Galia; Roman-Ramos, Rubén; Zamilpa, Alejandro; Herrera-Ruiz, Maribel; Rosas-Salgado, Gabriela; Tortoriello, Jaime; Jiménez-Ferrer, Enrique

    2014-01-01

    Sechium edule is traditionally used in Mexico as a therapeutic resource against renal diseases and to control high blood pressure. The purpose of this work is to evaluate the antihypertensive effect of the hydroalcoholic extract obtained from the roots of this plant, including its fractions and subfractions, on different hypertension models induced with angiotensin II (AG II). The hydroalcoholic extract was tested on an in vitro study of isolated aorta rings denuded of endothelial cells, using AG II as the agonist; this assay proved the vasorelaxant effect of this extract. Vagotomized rats were administered different doses of AG II as well as the Hydroalcoholic extract, which reduced blood pressure in 30 mmHg approximately; subsequently this extract was separated into two fractions (acetone and methanol) which were evaluated in the acute hypertension mouse model induced with AG II, where the acetone fraction was identified as the most effective one and was subsequently subfractioned using an open chromatographic column packed with silica gel. The subfractions were also evaluated in the acute hypertension model. Finally, the extract, fraction, and active subfraction were analyzed by MS-PDA-HPLC, identifying cinnamic derivative compounds like cinnamic acid methyl ester. PMID:24812568

  13. X-ray diffraction on (AgI)0.7- (NaPO3)0.3 and (AgI)0.8- (NaPO3)0.2 composites

    SciTech Connect

    Purwanto, A. . E-mail: purwanto@centrin.net.id; Kartini, E.; Sakuma, T.; Collins, M.F.; Kamiyama, T.

    2005-01-04

    We have identified the crystallographic phases of the melt-quenched superionic composites (AgI)0.7- (NaPO3)0.3 and (AgI)0.8- (NaPO3)0.2 by X-ray diffraction. Measurements were made in a temperature range from 300 to 630 deg. K. The materials have a glass phase and one or more crystalline phases. At 300 deg. K and at 350-bar K, the crystalline phase contains a 30:70 mixture of {beta}AgI and {gamma}AgI. Above 350 deg. K, the fraction of {beta}AgI increases and at 403-bar K it is the dominant phase with a {beta}{gamma} ratio of about 70:30 (slightly less in (AgI)0.8- (NaPO3)0.2). At 453, 523 and 623 deg. K the crystalline material is mainly {alpha}AgI. Crystalline 16-silver dodecaiodide diphosphate (Ag16I12P2O7) is also present between 373 and 523 deg. K at a 5-10% level. It disappears at 623-bar K because the crystal melts.

  14. Antibacterial activity and reusability of CNT-Ag and GO-Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Kim, Ji Dang; Yun, Hyosuk; Kim, Gwui Cheol; Lee, Chul Won; Choi, Hyun Chul

    2013-10-01

    A facile approach to the synthesis of novel CNT-Ag and GO-Ag antibacterial materials, in which thiol groups are utilized as linkers to secure silver (Ag) nanoparticles to the CNT and GO surfaces without agglomeration, is reported. The resulting CNT-Ag and GO-Ag samples were characterized by performing TEM, XRD, Auger, XPS, and Raman measurements, which revealed that in these antibacterial materials size-similar and quasi-spherical Ag nanoparticles are anchored to the CNT and GO surfaces. The Ag nanoparticles in CNT-Ag and GO-Ag have narrow size distributions with average diameters of 2.6 and 3.5 nm respectively. The antibacterial activities of CNT-Ag and GO-Ag against Escherichia coli were assessed with the paper-disk diffusion method and by determining the minimal inhibitory concentrations (MICs). CNT-Ag was found to have higher antibacterial activity than the reference Ag colloid. Moreover, both CNT-Ag and GO-Ag retain more than 50% of their original antibacterial activities after 20 washes with detergent, which indicates their potential as antibacterial materials for laboratory and medical purposes.

  15. Comparative Study of Antimicrobial Activity of AgBr and Ag Nanoparticles (NPs)

    PubMed Central

    Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

    2015-01-01

    The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60–70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120–130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends – the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains. PMID:25781988

  16. Trigonal prismatic Cu(I) and Ag(I) pyrazolato nanocage hosts: encapsulation of S8 and hydrocarbon guests.

    PubMed

    Duan, Peng-Cheng; Wang, Zhao-Yang; Chen, Jing-Huo; Yang, Guang; Raptis, Raphael G

    2013-11-14

    Two neutral hexanuclear trigonal prismatic cage molecules have been synthesized by coupling two planar triangular M3pz3-panels, M = Cu(I) and Ag(I), in eclipsed geometry. The ~230 Å(3) cage volume can be either vacant or occupied by neutral guests. The crystal structures of the M6-cyclohexane and Ag6-S8 host-guest species have been determined.

  17. A short proof of Weyl's law for fractional differential operators

    SciTech Connect

    Geisinger, Leander

    2014-01-15

    We study spectral asymptotics for a large class of differential operators on an open subset of R{sup d} with finite volume. This class includes the Dirichlet Laplacian, the fractional Laplacian, and also fractional differential operators with non-homogeneous symbols. Based on a sharp estimate for the sum of the eigenvalues we establish the first term of the semiclassical asymptotics. This generalizes Weyl's law for the Laplace operator.

  18. [Ablative and fractional lasers].

    PubMed

    Beylot, C; Grognard, C; Michaud, T

    2009-10-01

    The use of pulsed or scanning Carbon Dioxide, and pulsed Erbium-YAG lasers allows the programmable and reproducible photocoagulation of thin layers of the epidermis and superficial dermis. Thermal damage depends on the type of laser and is greater with CO(2) lasers. The degree of neocollagenesis is proportional to the thermal damage and is better with CO(2) lasers. Their main indication is the correction of photoaged facial skin but they can also be used for corrective dermatology, e.g. for scars and genodermatosis. Results are highly satisfactory but the technique is invasive and the patient experiences a social hindrance of around two weeks. Fractionated techniques treat 25% of the defective skin area at each session in noncontiguous microzones; four sessions are therefore necessary to treat the entire cutaneous surface. The treatment is given under topical anesthesia and is much less invasive, particularly with nonablative fractional laser treatment in which photothermolysis does not penetrate below the epidermis and/or the effects are slight, with no or very little social isolation. However, the results are much less satisfactory than the results of ablative laser and there is no firming effect. Other zones than the face can be treated. With the fractional CO(2) and Erbium ablative lasers, which have multiplied over the past 2 years, the much wider impacts cause perforation of the epidermis and there is a zone of ablation by laser photovaporization, with a zone of thermal damage below. The results are better in correcting photoaging of the face, without, however, achieving the efficacy of ablative lasers, which remain the reference technique. However, the effects are not insignificant, requiring at least 5 days of social isolation.

  19. Highly reliable ag nanowire flexible transparent electrode with mechanically welded junctions.

    PubMed

    Hwang, Byungil; Shin, Hae-A-Seul; Kim, Taegeon; Joo, Young-Chang; Han, Seung Min

    2014-08-27

    Deformation behavior of the Ag nanowire flexible transparent electrode under bending strain is studied and results in a novel approach for highly reliable Ag nanowire network with mechanically welded junctions. Bending fatigue tests up to 500,000 cycles are used to evaluate the in situ resistance change while imposing fixed, uniform bending strain. In the initial stages of bending cycles, the thermally annealed Ag nanowire networks show a reduction in fractional resistance followed by a transient and steady-state increase at later stages of cycling. SEM analysis reveals that the initial reduction in resistance is caused by mechanical welding as a result of applied bending strain, and the increase in resistance at later stages of cycling is determined to be due to the failure at the thermally locked-in junctions. Based on the observations from this study, a new methodology for highly reliable Ag nanowire network is proposed: formation of Ag nanowire networks with no prior thermal annealing but localized junction formation through simple application of mechanical bending strain. The non-annealed, mechanically welded Ag nanowire network shows significantly enhanced cyclic reliability with essentially 0% increase in resistance due to effective formation of localized wire-to-wire contact.

  20. Fractional channel multichannel analyzer

    DOEpatents

    Brackenbush, Larry W.; Anderson, Gordon A.

    1994-01-01

    A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynscronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board.

  1. Relative importance of the humic and fulvic fractions of natural organic matter in the aggregation and deposition of silver nanoparticles.

    PubMed

    Furman, Olha; Usenko, Sascha; Lau, Boris L T

    2013-02-01

    As engineered nanoparticles (NPs) are increasingly used, their entry into the environment has become an important topic for water sustainability. Recent investigations point to the critical role of natural organic matter (NOM) in altering the persistence of NPs by complexing with their surfaces. The NP-NOM complex, in turn, is the new entity that may potentially influence subsequent fate of NPs. To understand the relative impact of humic (HA) and fulvic fraction of NOM on the stability and mobility of silver nanoparticles (AgNPs), a combination of dynamic light scattering and quartz crystal microgravimetry with dissipation monitoring was used. In the absence of unbound NOM, (1) surface modification on either AgNP or silica substrate by different NOM fractions could lead to substantial changes in the extent and kinetics of AgNP aggregation and deposition, and (2) HA has a greater capability to enhance the transport of AgNPs by reducing their aggregation and deposition. With unbound NOM, HA seems to compete more successfully for binding sites on the substrate under electrostatically favorable conditions and formed a steric layer to prevent subsequent deposition of AgNPs. These findings highlighted the importance of NOM fraction in the overall environmental partitioning of AgNPs. PMID:23298221

  2. Long Memory in Finance and Fractional Brownian Motion

    NASA Astrophysics Data System (ADS)

    Kuroda, K.; Murai, J.

    We present a mathematical model of the trade signs and trade volumes, andderive a fractional Brownian motion as a scaling limit of the signed volume process which describes a super-diffusive nature. In our model, we assume that traders place a market order at a single time or divide their order into two chunks and place orders at different times. When they divide their order into two chunks, the probability distribution of the time lag t of divided orders is assumed to decay as an inverse power law of t with exponent α. We obtain three types of scaling limit of the signed volume process according to the three cases of the value of α, (i) α < 1, (ii) α = 1, and (iii) α > 1. (See Theorem 4.1.) We prove that a fractional Brownian motion having a super diffusive nature is obtained in a scaling limit of a signed volume process if and only if α < 1.

  3. Photostimulated Luminescence and Dynamics of AgI and Ag Nanoclusters in Zeolites

    SciTech Connect

    Chen, Wei; Joly, Alan G.; Roark, Joel

    2002-06-15

    The photoluminescence and photostimulated luminescence of Ag and AgI nanoclusters formed in zeolite-Y are studied using fluorescence spectroscopy. The photoluminescence spectra of AgI nanoclusters show emission from both AgI and Ag nanoclusters, while the in the photostimulated luminescence, only the emission of Ag clusters is observed. While the photoluminescence from both Ag and AgI particles displays both sub-nanosecond and microsecond lifetimes, the emission from photostimulated luminescence shows very short, picosecond lifetimes. A model which ascribes the photostimulated luminescence to recombination of electrons trapped in the zeolite with Ag in close proximity to the trap site is proposed. The appearance of strong photostimulated luminescence with short decays in these systems demonstrates that nanoparticles have potential for digital storage and medical radiology applications.

  4. Chemically-inactive interfaces in thin film Ag/AgI systems for resistive switching memories

    PubMed Central

    Cho, Deok-Yong; Tappertzhofen, Stefan; Waser, Rainer; Valov, Ilia

    2013-01-01

    AgI nanoionics-based resistive switching memories were studied in respect to chemical stability of the Ag/AgI interface using x-ray absorption spectroscopy. The apparent dissolution of Ag films of thickness below some tens of nanometers and the loss of electrode/electrolyte contact was critically addressed. The results evidently show that there are no chemical interactions at the interface despite the high ionic mobility of Ag ions. Simulation results further show that Ag metal clusters can form in the AgI layer with intermediate-range order at least up to next-next nearest neighbors, suggesting that Ag can permeate into the AgI only in an aggregated form of metal crystallite. PMID:23378904

  5. Robust Au-Ag-Au bimetallic atom-scale junctions fabricated by self-limited Ag electrodeposition at Au nanogaps.

    PubMed

    Hwang, Tai-Wei; Bohn, Paul W

    2011-10-25

    Atom-scale junctions (ASJs) exhibit quantum conductance behavior and have potential both for fundamental studies of adsorbate-mediated conductance in mesoscopic conductors and as chemical sensors. Electrochemically fabricated ASJs, in particular, show the stability needed for molecular detection applications. However, achieving physically robust ASJs at high yield is a challenge because it is difficult to control the direction and kinetics of metal deposition. In this work, a novel electrochemical approach is reported, in which Au-Ag-Au bimetallic ASJs are reproducibly fabricated from an initially prepared Au nanogap by sequential overgrowth and self-limited thinning. Applying a potential across specially prepared Au nanoelectrodes in the presence of aqueous Ag(I) leads to preferential galvanic reactions resulting in the deposition of Ag and the formation of an atom-scale junction between the electrodes. An external resistor is added in series with the ASJ to control self-termination, and adjusting solution chemical potential (concentration) is used to mediate self-thinning of junctions. The result is long-lived, mechanically stable ASJs that, unlike previous constructions, are stable in flowing solution, as well as to changes in solution media. These bimetallic ASJs exhibit a number of behaviors characteristic of quantum structures, including long-lived fractional conductance states, that are interpreted to arise from two or more quantized ASJs in series.

  6. What is a fractional derivative?

    NASA Astrophysics Data System (ADS)

    Ortigueira, Manuel D.; Tenreiro Machado, J. A.

    2015-07-01

    This paper discusses the concepts underlying the formulation of operators capable of being interpreted as fractional derivatives or fractional integrals. Two criteria for required by a fractional operator are formulated. The Grünwald-Letnikov, Riemann-Liouville and Caputo fractional derivatives and the Riesz potential are accessed in the light of the proposed criteria. A Leibniz rule is also obtained for the Riesz potential.

  7. Positive fractional linear electrical circuits

    NASA Astrophysics Data System (ADS)

    Kaczorek, Tadeusz

    2013-10-01

    The positive fractional linear systems and electrical circuits are addressed. New classes of fractional asymptotically stable and unstable electrical circuits are introduced. The Caputo and Riemann-Liouville definitions of fractional derivatives are used to analysis of the positive electrical circuits composed of resistors, capacitors, coils and voltage (current) sources. The positive fractional electrical and specially unstable different types electrical circuits are analyzed. Some open problems are formulated.

  8. Experimental observation of fractional echoes

    NASA Astrophysics Data System (ADS)

    Karras, G.; Hertz, E.; Billard, F.; Lavorel, B.; Siour, G.; Hartmann, J.-M.; Faucher, O.; Gershnabel, Erez; Prior, Yehiam; Averbukh, Ilya Sh.

    2016-09-01

    We report the observation of fractional echoes in a double-pulse excited nonlinear system. Unlike standard echoes, which appear periodically at delays which are integer multiples of the delay between the two exciting pulses, the fractional echoes appear at rational fractions of this delay. We discuss the mechanism leading to this phenomenon, and provide experimental demonstration of fractional echoes by measuring third harmonic generation in a thermal gas of CO2 molecules excited by a pair of femtosecond laser pulses.

  9. Hydrolysis and fractionation of lignocellulosic biomass

    DOEpatents

    Torget, Robert W.; Padukone, Nandan; Hatzis, Christos; Wyman, Charles E.

    2000-01-01

    A multi-function process is described for the hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components such as extractives and proteins; a portion of the solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass comprising one or more of the following: optionally, as function 1, introducing a dilute acid of pH 1.0-5.0 into a continual shrinking bed reactor containing a lignocellulosic biomass material at a temperature of about 94 to about 160.degree. C. for a period of about 10 to about 120 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of extractives, lignin, and protein by keeping the solid to liquid ratio constant throughout the solubilization process; as function 2, introducing a dilute acid of pH 1.0-5.0, either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing either fresh biomass or the partially fractionated lignocellulosic biomass material from function 1 at a temperature of about 94-220.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of hemicellulosic sugars, semisoluble sugars and other compounds, and amorphous glucans by keeping the solid to liquid ratio constant throughout the solubilization process; as function 3, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 2 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process; and as function 4

  10. Fractional diffusion on bounded domains

    SciTech Connect

    Defterli, Ozlem; D'Elia, Marta; Du, Qiang; Gunzburger, Max Donald; Lehoucq, Richard B.; Meerschaert, Mark M.

    2015-03-13

    We found that the mathematically correct specification of a fractional differential equation on a bounded domain requires specification of appropriate boundary conditions, or their fractional analogue. In this paper we discuss the application of nonlocal diffusion theory to specify well-posed fractional diffusion equations on bounded domains.

  11. Ag diffusion in cubic silicon carbide

    NASA Astrophysics Data System (ADS)

    Shrader, David; Khalil, Sarah M.; Gerczak, Tyler; Allen, Todd R.; Heim, Andrew J.; Szlufarska, Izabela; Morgan, Dane

    2011-01-01

    The diffusion of Ag impurities in bulk 3C-SiC is studied using ab initio methods based on density functional theory. This work is motivated by the desire to reduce transport of radioactive Ag isotopes through the SiC boundary layer in the Tristructural-Isotropic (TRISO) fuel pellet, which is a significant concern for the Very High Temperature Reactor (VHTR) nuclear reactor concept. The structure and stability of charged Ag and Ag-vacancy clusters in SiC are calculated. Relevant intrinsic SiC defect energies are also determined. The most stable state for the Ag impurity in SiC is found to be a Ag atom substituting on the Si sub-lattice and bound to a C vacancy. Bulk diffusion coefficients are estimated for different impurity states and values are all found to have very high activation energy. The impurity state with the lowest activation energy for diffusion is found to be the Ag interstitial, with an activation energy of approximately 7.9 eV. The high activation energies for Ag diffusion in bulk 3C-SiC cause Ag transport to be very slow in the bulk and suggests that observed Ag transport in this material is due to an alternative mechanism (e.g., grain boundary diffusion).

  12. Fractionation of Subcellular Organelles.

    PubMed

    Graham, John M

    2015-01-01

    This unit provides both a theoretical and a practical background to all the techniques associated with the application of differential and density gradient centrifugation for the analysis of subcellular membranes. The density gradient information focuses on the use of the modern gradient solute iodixanol, chosen for its ease of use, versatility, and compatibility with biological particles. Its use in both pre-formed discontinuous and continuous gradients and in self-generated gradients is discussed. Considerable emphasis is given to selection of the appropriate centrifuge rotors and tubes and their influence on the methods used for creation, fractionation, and analysis of density gradients. Without proper consideration of these critical ancillary procedures, the resolving power of the gradient can be easily compromised. PMID:26621372

  13. Fractionation of Subcellular Organelles.

    PubMed

    Graham, John M

    2015-12-01

    This unit provides both a theoretical and a practical background to all the techniques associated with the application of differential and density gradient centrifugation for the analysis of subcellular membranes. The density gradient information focuses on the use of the modern gradient solute iodixanol, chosen for its ease of use, versatility, and compatibility with biological particles. Its use in both pre-formed discontinuous and continuous gradients and in self-generated gradients is discussed. Considerable emphasis is given to selection of the appropriate centrifuge rotors and tubes and their influence on the methods used for creation, fractionation, and analysis of density gradients. Without proper consideration of these critical ancillary procedures, the resolving power of the gradient can be easily compromised.

  14. Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene.

    PubMed

    Cai, P-F; Su, C-J; Chang, W-T; Chang, F-C; Peng, C-Y; Sun, I-W; Wei, Y-L; Jou, C-J; Wang, H Paul

    2014-08-30

    Drinking water shortage has become worse in recent decades. A new capacitive deionization (CDI) method for increasing water supplies through the effective desalination of seawater has been developed. Silver as nano Ag and Ag@C which was prepared by carbonization of the Ag(+)-β-cyclodextrin complex at 573 K for 30 min can add the antimicrobial function into the CDI process. The Ag@C and Ag nanoparticles dispersed on reduced graphene oxide (Ag@C/rGO and nano Ag/rGO) were used as the CDI electrodes. The nano Ag/rGO and Ag@C/rGO electrodes can reduce the charging resistant, and enhance the electrosorption capability. Better CDI efficiencies with the nano Ag/rGO and Ag@C/rGO electrodes can therefore be obtained. When reversed the voltage, the electrodes can be recovered up to 90% within 5 min. This work presents the feasibility for the nano Ag and Ag@C on rGO electrodes applied in CDI process to produce drinking water from seawater or saline water.

  15. Ag/AgBr/TiO2 visible light photocatalyst for destruction of azodyes and bacteria.

    PubMed

    Hu, Chun; Lan, Yongqing; Qu, Jiuhui; Hu, Xuexiang; Wang, Aimin

    2006-03-01

    Ag/AgBr/TiO2 was prepared by the deposition-precipitation method and was found to be a novel visible light driven photocatalyst. The catalyst showed high efficiency for the degradation of nonbiodegradable azodyes and the killing of Escherichia coli under visible light irradiation (lambda>420 nm). The catalyst activity was maintained effectively after successive cyclic experiments under UV or visible light irradiation without the destruction of AgBr. On the basis of the characterization of X-ray diffraction, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, the surface Ag species mainly exist as Ag0 in the structure of all samples before and after reaction, and Ag0 species scavenged hVB+ and then trapped eCB- in the process of photocatalytic reaction, inhibiting the decomposition of AgBr. The studies of ESR and H2O2 formation revealed that *OH and O2*- were formed in visible light irradiated aqueous Ag/AgBr/TiO2 suspension, while there was no reactive oxygen species in the visible light irradiated Ag0/TiO2 system. The results indicate that AgBr is the main photoactive species for the destruction of azodyes and bacteria under visible light. In addition, the bactericidal efficiency and killing mechanism of Ag/AgBr/TiO2 under visible light irradiation are illustrated and discussed. PMID:16509698

  16. Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene.

    PubMed

    Cai, P-F; Su, C-J; Chang, W-T; Chang, F-C; Peng, C-Y; Sun, I-W; Wei, Y-L; Jou, C-J; Wang, H Paul

    2014-08-30

    Drinking water shortage has become worse in recent decades. A new capacitive deionization (CDI) method for increasing water supplies through the effective desalination of seawater has been developed. Silver as nano Ag and Ag@C which was prepared by carbonization of the Ag(+)-β-cyclodextrin complex at 573 K for 30 min can add the antimicrobial function into the CDI process. The Ag@C and Ag nanoparticles dispersed on reduced graphene oxide (Ag@C/rGO and nano Ag/rGO) were used as the CDI electrodes. The nano Ag/rGO and Ag@C/rGO electrodes can reduce the charging resistant, and enhance the electrosorption capability. Better CDI efficiencies with the nano Ag/rGO and Ag@C/rGO electrodes can therefore be obtained. When reversed the voltage, the electrodes can be recovered up to 90% within 5 min. This work presents the feasibility for the nano Ag and Ag@C on rGO electrodes applied in CDI process to produce drinking water from seawater or saline water. PMID:24928455

  17. Facile synthesis of S-Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S-Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70-160 nm and lengths of 200-360 nm. X-ray diffraction of the S-Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag+ plays an important role in controlling the size and morphology of the S-Ag nanocomposites. When the molar ratio of PVP to Ag+ was 10:1, smaller sizes, better dispersibility and narrower distribution of S-Ag nanocomposites with diameters of 10-40 nm were obtained. The formation mechanism of the S-Ag nanocomposites was studied by designing a series of experiments using ultraviolet-visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag+ becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S-Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S-Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles.

  18. Facile synthesis of S–Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S–Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70–160 nm and lengths of 200–360 nm. X-ray diffraction of the S–Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag+ plays an important role in controlling the size and morphology of the S–Ag nanocomposites. When the molar ratio of PVP to Ag+ was 10:1, smaller sizes, better dispersibility and narrower distribution of S–Ag nanocomposites with diameters of 10–40 nm were obtained. The formation mechanism of the S–Ag nanocomposites was studied by designing a series of experiments using ultraviolet–visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag+ becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S–Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S–Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles.

  19. Interaction of a converging laser beam with a Ag colloidal solution during the ablation of a Ag target in water.

    PubMed

    Resano-Garcia, Amandine; Battie, Yann; Naciri, Aotmane En; Chaoui, Nouari

    2016-05-27

    We studied the nanosecond laser-induced shape modifications of Ag colloids exposed to a converging laser beam during the ablation of a Ag target in water. To this end, we performed a series of laser ablation experiments in which the laser energy was varied while all other parameters were kept constant. In addition to transmission electron microscopy (TEM), the shape distribution of the Ag nanoparticles was determined by modelling the extinction spectra of the final colloidal solutions using theoretical calculations based on shape distributed effective medium theory (SDEMT). From these calculations, two physical parameters named sphericity and dispersity were introduced and used to gauge the evolution of the shape distribution of the particles. As the laser energy on the target was increased from 5 to 20 mJ/pulse, an apparently abrupt modification of the shape distribution of the particles was evidenced by both TEM and SDEMT calculations. This change is explained in terms of competitive fragmentation, growth and reshaping processes. On the basis the heating-melting-vaporization model, we demonstrate how the competition between these processes, occurring at different locations of the converging beam, determines the shape distribution of the final product. We highlight the relevance of the fluence gradient along the beam path and the laser interaction volume on the laser-induced modifications of the suspended particles during the ablation process. PMID:27095289

  20. Interaction of a converging laser beam with a Ag colloidal solution during the ablation of a Ag target in water

    NASA Astrophysics Data System (ADS)

    Resano-Garcia, Amandine; Battie, Yann; Naciri, Aotmane En; Chaoui, Nouari

    2016-05-01

    We studied the nanosecond laser-induced shape modifications of Ag colloids exposed to a converging laser beam during the ablation of a Ag target in water. To this end, we performed a series of laser ablation experiments in which the laser energy was varied while all other parameters were kept constant. In addition to transmission electron microscopy (TEM), the shape distribution of the Ag nanoparticles was determined by modelling the extinction spectra of the final colloidal solutions using theoretical calculations based on shape distributed effective medium theory (SDEMT). From these calculations, two physical parameters named sphericity and dispersity were introduced and used to gauge the evolution of the shape distribution of the particles. As the laser energy on the target was increased from 5 to 20 mJ/pulse, an apparently abrupt modification of the shape distribution of the particles was evidenced by both TEM and SDEMT calculations. This change is explained in terms of competitive fragmentation, growth and reshaping processes. On the basis the heating–melting–vaporization model, we demonstrate how the competition between these processes, occurring at different locations of the converging beam, determines the shape distribution of the final product. We highlight the relevance of the fluence gradient along the beam path and the laser interaction volume on the laser-induced modifications of the suspended particles during the ablation process.

  1. Synthesis and formation mechanism of Ag-Ni alloy nanoparticles at room temperature

    NASA Astrophysics Data System (ADS)

    Yan, Shi; Sun, Dongbai; Tan, Yuanyuan; Xing, Xueqing; Yu, Hongying; Wu, Zhonghua

    2016-11-01

    Ag-Ni nanoparticles were prepared with a chemical reduction method in the presence of polyvinylpyrrolidone (PVP) used as a stabilizing agent. During the synthesis of Ag-Ni nanoparticles, silver nitrate was used as the Ag+ source while nickel sulfate hexahydrate was used as Ni2+ source. Mixed solutions of Ag+ source and Ni2+ source were used as the precursors and sodium borohydride was used as the reducing agent. Five ratios of Ag+/Ni2+ (9:1, 3:1, 1:1, 1:3, and 1:9) suspensions were prepared in the corresponding precursors. Ag-Ni alloy nanoparticles were obtained with this method at room temperature. Scanning electronic microscope (SEM), energy dispersive spectrum (EDS), high resolution transmission electron microscope (HRTEM) were used to characterize the morphology, composition and crystal structure of the nanoparticles. The crystal structure was also investigated with X-ray diffraction (XRD). In all five Ag/Ni ratios, two kinds of particle structures were observed that are single crystal structure and five-fold twinned structure respectively. Free energy of nanoparticles with different crystal structures were calculated at each Ag/Ni ratio. Calculated results revealed that, with identical volume, free energy of single crystal particle is lower than multi-twinned particle and the difference becomes smaller with the increase of particle size; increase of Ni content will lead the increase of free energy for both structures. Formation of different crystal structures are decided by the structure of the original nuclei at the very early stage of the reduction process.

  2. Characterization and mechanical properties investigation of TiN-Ag films onto Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Du, Dongxing; Liu, Daoxin; Zhang, Xiaohua; Tang, Jingang; Xiang, Dinggen

    2016-03-01

    To investigate their effect on fretting fatigue (FF) resistance of a Ti-6Al-4V alloy, hard solid lubricating composite films of TiN with varying silver contents (TiN-Ag) were deposited on a Ti-6Al-4V alloy using ion-assisted magnetron sputtering. The surface morphology and structure were analyzed by atomic force microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy. The hardness, bonding strength, and toughness of films were tested using a micro-hardness tester, scratch tester, and a repeated press-press test system that was manufactured in-house, respectively. The FF resistance of TiN-Ag composite films was studied using self-developed devices. The results show that the FF resistance of a titanium alloy can be improved by TiN-Ag composite films, which were fabricated using hard TiN coating doped with soft Ag. The FF life of Ag0.5, Ag2, Ag5, Ag10 and Ag20 composite films is 2.41, 3.18, 3.20, 2.94 and 2.87 times as great as that of the titanium alloy, respectively. This is because the composite films have the better toughness, friction lubrication, and high bonding strength. When the atomic fraction of Ag changes from 2% to 5%, the FF resistance of the composite films shows the best performance. This is attributed to the surface integrity of the composite film is sufficiently fine to prevent the initiation and early propagation of FF cracks.

  3. AgI/Ag{sub 3}PO{sub 4} hybrids with highly efficient visible-light driven photocatalytic activity

    SciTech Connect

    Katsumata, Hideyuki; Hayashi, Takahiro; Taniguchi, Masanao; Suzuki, Tohru; Kaneco, Satoshi

    2015-03-15

    Highlights: • AgI/Ag{sub 3}PO{sub 4} hybrid was prepared via an in situ anion-exchange method. • AgI/Ag{sub 3}PO{sub 4} displays the excellent photocatalytic activity under visible light. • AgI/Ag{sub 3}PO{sub 4} readily transforms to be Ag@AgI/Ag{sub 3}PO{sub 4} system. • h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization over AgI/Ag{sub 3}PO{sub 4}. • The activity enhancement is ascribed to a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI. - Abstract: Highly efficient visible-light-driven AgI/Ag{sub 3}PO{sub 4} hybrid photocatalysts with different mole ratios of AgI were prepared via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgI/Ag{sub 3}PO{sub 4} photocatalysts displayed the higher photocatalytic activity than pure Ag{sub 3}PO{sub 4} and AgI for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgI/Ag{sub 3}PO{sub 4} with 80% of AgI exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgI/Ag{sub 3}PO{sub 4} readily transformed to be Ag@AgI/Ag{sub 3}PO{sub 4} system while the photocatalytic activity of AgI/Ag{sub 3}PO{sub 4} remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgI/Ag{sub 3}PO{sub 4} hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI, in which Ag nanoparticles act as the charge separation center.

  4. A percolative approach to investigate electromigration failure in printed Ag structures

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Mamidanna, Avinash; Lefky, Christopher; Hildreth, Owen; Alford, T. L.

    2016-09-01

    The ease of fabrication and wide application of printed microelectronics are driving advances in reactive inks. The long-term performance of structures printed using reactive ink is important for their application in microelectronics. In this study, silver lines are printed with low-temperature, self-reducing, silver-diamine based ink. The electromigration failure of the printed silver is first studied using Black's equation. However, due to the porous nature of the printed Ag line, Black's equation is not the best fit for predicting the lifetime, this is because Black's equation does not take into account morphology-induced current crowding. We find that the resistivity of the printed Ag lines can be described (as a function of void fraction) by percolation theory. In addition, we also demonstrate that the failure lifetimes of the printed Ag can be predicted quite well by a percolative model of failure.

  5. Visible-light-driven photocatalysts Ag/AgCl dispersed on mesoporous Al2O3 with enhanced photocatalytic performance.

    PubMed

    Feng, Zhouzhou; Yu, Jiajie; Sun, Dongping; Wang, Tianhe

    2016-10-15

    In this paper, Ag/AgCl and Ag/AgCl/Al2O3 photocatalysts were synthesized via a precipitation reaction between NaCl and CH3COOAg or Ag(NH3)2NO3, wherein Ag/AgCl was immobilized into mesoporous Al2O3 medium. The Ag/AgCl-based nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, and so on. The photocatalysts displayed excellent photocatalytic activity for the degradations of methyl orange (MO) and methylene blue (MB) pollutants under visible light irradiation. The Ag/AgCl(CH3COOAg)/Al2O3 sample exhibited the best photocatalytic performance, degrading 99% MO after 9min of irradiation, which was 1.1 times, 1.22 times and 1.65 times higher than that of Ag/AgCl(Ag(NH3)2NO3)/Al2O3, Ag/AgCl(CH3COOAg) and Ag/AgCl(Ag(NH3)2NO3) photocatalyst, respectively. Meanwhile, Ag/AgCl(CH3COOAg)/Al2O3 also showed excellent capability of MB degradation. Compared to the data reported for Ag/AgCl/TiO2, the Ag/AgCl/Al2O3 prepared in this work exhibited a good performance for the degradation of methyl orange (MO). The results suggest that the dispersion of Ag/AgCl on mesoporous Al2O3 strongly affected their photocatalytic activities. O2(-), OH radicals and Cl(0) atoms are main active species during photocatalysis. PMID:27442145

  6. Excitons in AgI-BASED-GLASSES and -

    NASA Astrophysics Data System (ADS)

    Fujishiro, Fumito; Mochizuki, Shosuke

    2007-01-01

    We summarize our recent optical studies on different pristine AgI films, different AgI-based glasses and different AgI-oxide fine particle composites. The exciton spectra of these specimens give useful information about the ionic and electronic structures at the AgI/glass and AgI/oxide particle interfaces.

  7. Removal of transuranics from Johnston Island soil by fractional classification

    SciTech Connect

    Sunderland, N.R.

    1987-06-07

    The following conclusions were reached as a result of the research conducted with the TRUclean process on Johnston Island: Processed materials will have a total TRU activity of less than 500 Bq/Kg. Approximately 90% of the TRU activity in coral/soil is removed by a single pass through the fractional classification process. A volume reduction of greater than 90% of the original contaminated volume can be achieved with the returned ''clean'' volume less than or equal to the cleanup criteria. Reprocessing or multiple staging of the process units will yield overall efficiencies of greater than 90%. Continued testing at Nevada Test Site confirmed these conclusions.

  8. The cardiovascular response to the AGS

    NASA Technical Reports Server (NTRS)

    Cardus, David; Mctaggart, Wesley G.

    1993-01-01

    This paper reports the preliminary results of experiments on human subjects conducted to study the cardiovascular response to various g-levels and exposure times using an artificial gravity simulator (AGS). The AGS is a short arm centrifuge consisting of a turntable, a traction system, a platform and four beds. Data collection hardware is part of the communication system. The AGS provides a steep acceleration gradient in subjects in the supine position.

  9. Fractionally charged skyrmions in fractional quantum Hall effect

    NASA Astrophysics Data System (ADS)

    Balram, Ajit C.; Wurstbauer, U.; Wójs, A.; Pinczuk, A.; Jain, J. K.

    2015-11-01

    The fractional quantum Hall effect has inspired searches for exotic emergent topological particles, such as fractionally charged excitations, composite fermions, abelian and nonabelian anyons and Majorana fermions. Fractionally charged skyrmions, which support both topological charge and topological vortex-like spin structure, have also been predicted to occur in the vicinity of 1/3 filling of the lowest Landau level. The fractional skyrmions, however, are anticipated to be exceedingly fragile, suppressed by very small Zeeman energies. Here we show that, slightly away from 1/3 filling, the smallest manifestations of the fractional skyrmion exist in the excitation spectrum for a broad range of Zeeman energies, and appear in resonant inelastic light scattering experiments as well-defined resonances slightly below the long wavelength spin wave mode. The spectroscopy of these exotic bound states serves as a sensitive tool for investigating the residual interaction between composite fermions, responsible for delicate new fractional quantum Hall states in this filling factor region.

  10. Fractionally charged skyrmions in fractional quantum Hall effect.

    PubMed

    Balram, Ajit C; Wurstbauer, U; Wójs, A; Pinczuk, A; Jain, J K

    2015-01-01

    The fractional quantum Hall effect has inspired searches for exotic emergent topological particles, such as fractionally charged excitations, composite fermions, abelian and nonabelian anyons and Majorana fermions. Fractionally charged skyrmions, which support both topological charge and topological vortex-like spin structure, have also been predicted to occur in the vicinity of 1/3 filling of the lowest Landau level. The fractional skyrmions, however, are anticipated to be exceedingly fragile, suppressed by very small Zeeman energies. Here we show that, slightly away from 1/3 filling, the smallest manifestations of the fractional skyrmion exist in the excitation spectrum for a broad range of Zeeman energies, and appear in resonant inelastic light scattering experiments as well-defined resonances slightly below the long wavelength spin wave mode. The spectroscopy of these exotic bound states serves as a sensitive tool for investigating the residual interaction between composite fermions, responsible for delicate new fractional quantum Hall states in this filling factor region. PMID:26608906

  11. Fractionally charged skyrmions in fractional quantum Hall effect

    PubMed Central

    Balram, Ajit C.; Wurstbauer, U.; Wójs, A.; Pinczuk, A.; Jain, J. K.

    2015-01-01

    The fractional quantum Hall effect has inspired searches for exotic emergent topological particles, such as fractionally charged excitations, composite fermions, abelian and nonabelian anyons and Majorana fermions. Fractionally charged skyrmions, which support both topological charge and topological vortex-like spin structure, have also been predicted to occur in the vicinity of 1/3 filling of the lowest Landau level. The fractional skyrmions, however, are anticipated to be exceedingly fragile, suppressed by very small Zeeman energies. Here we show that, slightly away from 1/3 filling, the smallest manifestations of the fractional skyrmion exist in the excitation spectrum for a broad range of Zeeman energies, and appear in resonant inelastic light scattering experiments as well-defined resonances slightly below the long wavelength spin wave mode. The spectroscopy of these exotic bound states serves as a sensitive tool for investigating the residual interaction between composite fermions, responsible for delicate new fractional quantum Hall states in this filling factor region. PMID:26608906

  12. Fractionally charged skyrmions in fractional quantum Hall effect.

    PubMed

    Balram, Ajit C; Wurstbauer, U; Wójs, A; Pinczuk, A; Jain, J K

    2015-11-26

    The fractional quantum Hall effect has inspired searches for exotic emergent topological particles, such as fractionally charged excitations, composite fermions, abelian and nonabelian anyons and Majorana fermions. Fractionally charged skyrmions, which support both topological charge and topological vortex-like spin structure, have also been predicted to occur in the vicinity of 1/3 filling of the lowest Landau level. The fractional skyrmions, however, are anticipated to be exceedingly fragile, suppressed by very small Zeeman energies. Here we show that, slightly away from 1/3 filling, the smallest manifestations of the fractional skyrmion exist in the excitation spectrum for a broad range of Zeeman energies, and appear in resonant inelastic light scattering experiments as well-defined resonances slightly below the long wavelength spin wave mode. The spectroscopy of these exotic bound states serves as a sensitive tool for investigating the residual interaction between composite fermions, responsible for delicate new fractional quantum Hall states in this filling factor region.

  13. Fractionally charged skyrmions in fractional quantum Hall effect

    SciTech Connect

    Balram, Ajit C.; Wurstbauer, U.; Wójs, A.; Pinczuk, A.; Jain, J. K.

    2015-11-26

    The fractional quantum Hall effect has inspired searches for exotic emergent topological particles, such as fractionally charged excitations, composite fermions, abelian and nonabelian anyons and Majorana fermions. Fractionally charged skyrmions, which support both topological charge and topological vortex-like spin structure, have also been predicted to occur in the vicinity of 1/3 filling of the lowest Landau level. The fractional skyrmions, however, are anticipated to be exceedingly fragile, suppressed by very small Zeeman energies. Here we show that, slightly away from 1/3 filling, the smallest manifestations of the fractional skyrmion exist in the excitation spectrum for a broad range of Zeeman energies, and appear in resonant inelastic light scattering experiments as well-defined resonances slightly below the long wavelength spin wave mode. The spectroscopy of these exotic bound states serves as a sensitive tool for investigating the residual interaction between composite fermions, responsible for delicate new fractional quantum Hall states in this filling factor region.

  14. Capacitive Sensing Of Gaseous Fraction In Two-Phase Flow

    NASA Technical Reports Server (NTRS)

    Crowley, Christopher J.; Sahm, Michael K.

    1995-01-01

    Instrument makes nonintrusive, real-time capacitive measurements to determine volume fraction of vapor or other gas in flowing, electrically nonconductive liquid/gas mixture. Works even with liquids having relatively low permittivities. Useful for measuring proportions of vapor in boiling, condensing, and flowing heat-transfer fluids and in cryogenic fluids.

  15. AgRP Neurons Regulate Bone Mass.

    PubMed

    Kim, Jae Geun; Sun, Ben-Hua; Dietrich, Marcelo O; Koch, Marco; Yao, Gang-Qing; Diano, Sabrina; Insogna, Karl; Horvath, Tamas L

    2015-10-01

    The hypothalamus has been implicated in skeletal metabolism. Whether hunger-promoting neurons of the arcuate nucleus impact the bone is not known. We generated multiple lines of mice to affect AgRP neuronal circuit integrity. We found that mice with Ucp2 gene deletion, in which AgRP neuronal function was impaired, were osteopenic. This phenotype was rescued by cell-selective reactivation of Ucp2 in AgRP neurons. When the AgRP circuitry was impaired by early postnatal deletion of AgRP neurons or by cell autonomous deletion of Sirt1 (AgRP-Sirt1(-/-)), mice also developed reduced bone mass. No impact of leptin receptor deletion in AgRP neurons was found on bone homeostasis. Suppression of sympathetic tone in AgRP-Sirt1(-/-) mice reversed osteopenia in transgenic animals. Taken together, these observations establish a significant regulatory role for AgRP neurons in skeletal bone metabolism independent of leptin action. PMID:26411686

  16. Multiple Partial Siberian Snakes in the AGS

    SciTech Connect

    Takano, J.; Ahrens, L. A.; Bai, M.; Brown, K.; Courant, E. D.; Gardner, C. J.; Glenn, J. W.; Huang, H.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.; Hattori, T.; Lin, F.

    2007-06-13

    Polarized protons are accelerated up to 24.3 GeV in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). To accelerate the beam with preserving the polarization, two different types of helical dipole partial Siberian snake have been installed to the AGS. One is a superconducting magnet (Cold Snake, CSNK), and the other is a normal conducting one (Warm Snake, WSNK). With these snake magnets, the polarization at the AGS extraction achieved 65%. However, the AGS has spin mismatches at the injection and extraction. This description shows calculated results to have better spin matching with using two or three snakes.

  17. Size-dependent cytotoxicity of silver nanoparticles in human lung cells: the role of cellular uptake, agglomeration and Ag release

    PubMed Central

    2014-01-01

    Background Silver nanoparticles (AgNPs) are currently one of the most manufactured nanomaterials. A wide range of toxicity studies have been performed on various AgNPs, but these studies report a high variation in toxicity and often lack proper particle characterization. The aim of this study was to investigate size- and coating-dependent toxicity of thoroughly characterized AgNPs following exposure of human lung cells and to explore the mechanisms of toxicity. Methods BEAS-2B cells were exposed to citrate coated AgNPs of different primary particle sizes (10, 40 and 75 nm) as well as to 10 nm PVP coated and 50 nm uncoated AgNPs. The particle agglomeration in cell medium was investigated by photon cross correlation spectroscopy (PCCS); cell viability by LDH and Alamar Blue assay; ROS induction by DCFH-DA assay; genotoxicity by alkaline comet assay and γH2AX foci formation; uptake and intracellular localization by transmission electron microscopy (TEM); and cellular dose as well as Ag release by atomic absorption spectroscopy (AAS). Results The results showed cytotoxicity only of the 10 nm particles independent of surface coating. In contrast, all AgNPs tested caused an increase in overall DNA damage after 24 h assessed by the comet assay, suggesting independent mechanisms for cytotoxicity and DNA damage. However, there was no γH2AX foci formation and no increased production of intracellular reactive oxygen species (ROS). The reasons for the higher toxicity of the 10 nm particles were explored by investigating particle agglomeration in cell medium, cellular uptake, intracellular localization and Ag release. Despite different agglomeration patterns, there was no evident difference in the uptake or intracellular localization of the citrate and PVP coated AgNPs. However, the 10 nm particles released significantly more Ag compared with all other AgNPs (approx. 24 wt% vs. 4–7 wt%) following 24 h in cell medium. The released fraction in cell medium did not induce any

  18. Fractionated Stereotactic Radiotherapy for Facial Nerve Schwannomas.

    PubMed

    Shi, Wenyin; Jain, Varsha; Kim, Hyun; Champ, Colin; Jain, Gaurav; Farrell, Christopher; Andrews, David W; Judy, Kevin; Liu, Haisong; Artz, Gregory; Werner-Wasik, Maria; Evans, James J

    2016-02-01

    Purpose Data on the clinical course of irradiated facial nerve schwannomas (FNS) are lacking. We evaluated fractionated stereotactic radiotherapy (FSRT) for FNS. Methods Eight consecutive patients with FNS treated at our institution between 1998 and 2011 were included. Patients were treated with FSRT to a median dose of 50.4 Gy (range: 46.8-54 Gy) in 1.8 or 2.0 Gy fractions. We report the radiographic response, symptom control, and toxicity associated with FSRT for FNS. Results The median follow-up time was 43 months (range: 10-75 months). All patients presented with symptoms including pain, tinnitus, facial asymmetry, diplopia, and hearing loss. The median tumor volume was 1.57 cc. On the most recent follow-up imaging, five patients were noted to have stable tumor size; three patients had a net reduction in tumor volume. Additionally, six patients had improvement in clinical symptoms, one patient had stable clinical findings, and one patient had worsened House-Brackmann grade due to cystic degeneration. Conclusion FSRT treatment of FNS results in excellent control of growth and symptoms with a small rate of radiation toxicity. Given the importance of maintaining facial nerve function, FSRT could be considered as a primary management modality for enlarging or symptomatic FNS. PMID:26949592

  19. Bimetallic Ag-Au nanoparticles: Extracting meaningful optical constants from the surface-plasmon extinction spectrum

    NASA Astrophysics Data System (ADS)

    Moskovits, M.; Srnova-Sloufova, I.; Vlckova, B.

    2002-06-01

    We report an approach for extracting the optical constants of bimetallic Ag-Au nanoparticles from the measured surface-plasmon (SP) extinction spectra. The dielectric function of the metal is expressed as an analytic function of the wavelength in which the interband (and all other non-Drude) contributions to the dielectric function are represented by a sum of Lorentz functions. This expression is then used to fit the experimental extinction spectra to appropriate functions based on Mie theory. Three Lorentz functions (plus a Drude term) were found to be sufficient to reproduce the dielectric functions of Ag and Au [P. B. Johnson and R. W. Christy, Phys. Rev. B 6, 4370 (1972)] over the entire 0.6-6.5 eV range reported. With functions of this type, an excellent multiparameter fit of the measured extinction spectrum of colloidal Ag was obtained. Extinction spectra of a series of (Ag)Au hydrosols, prepared by reducing a gold precursor in the presence of previously synthesized silver seed particles with Au mole fractions ranging from 0.1 to 0.8, were measured. The extinction spectra show a single band (attributed to the surface plasmon) for all of the colloids produced, suggesting alloy formation. Transmission electron microscopy (TEM) images, however, indicate clear core-shell contrast for nanoparticles with Au mole fractions 0.4 and higher. With a presumed particle structure consisting of Ag core and Ag/Au alloy shell, very good fits were obtained for all of the measured extinction spectra by using a fitting strategy that restricted the number of parameters allowed to vary freely in the aforementioned dielectric function. The values of the dielectric function of the presumed shells were extracted in this manner as a function of wavelength. For particles with Au mole fraction 0.1-0.3, the results suggest an incompletely formed shell. For particles with higher Au mole fractions, the dielectric function of the shell gradually approaches that of Au. Overall, the results

  20. Toxicokinetics of Ag in the terrestrial isopod Porcellionides pruinosus exposed to Ag NPs and AgNO₃ via soil and food.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Morgan, A John; Kille, Peter; Svendsen, Claus; Jurkschat, Kerstin; Mosselmans, J Fred W; Soares, Amadeu M V M; Loureiro, Susana

    2016-03-01

    Silver nanoparticles (Ag NPs) have been used in numerous consumer products and may enter the soil through the land application of biosolids. However, little is known about the relationship between Ag NP exposure and their bioavailability for soil organisms. This study aims at comparing the uptake and elimination kinetics of Ag upon exposures to different Ag forms (NPs and ionic Ag (as AgNO3)) in the isopod Porcellionides pruinosus. Isopods were exposed to contaminated Lufa 2.2 soil or alder leaves as food. Uptake and elimination rate constants for soil exposure did not significantly differ between Ag NPs and ionic Ag at 30 and 60 mg Ag/kg. For dietary exposure, the uptake rate constant was up to 5 times higher for Ag NPs than for AgNO3, but this was related to feeding activity and exposure concentrations, while no difference in the elimination rate constants was found. When comparing both routes, dietary exposure resulted in lower Ag uptake rate constants but elimination rate constants did not differ. A fast Ag uptake was observed from both routes and most of the Ag taken up seemed not to be eliminated. Synchrotron X-ray fluorescence showed Ag in the S-cells of the hepatopancreas, thus supporting the observations from the kinetic experiment (i.e. low elimination). In addition, our results show that isopods have an extremely high Ag accumulation capacity, suggesting the presence of an efficient Ag storage compartment. PMID:26581474

  1. Toxicokinetics of Ag in the terrestrial isopod Porcellionides pruinosus exposed to Ag NPs and AgNO₃ via soil and food.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Morgan, A John; Kille, Peter; Svendsen, Claus; Jurkschat, Kerstin; Mosselmans, J Fred W; Soares, Amadeu M V M; Loureiro, Susana

    2016-03-01

    Silver nanoparticles (Ag NPs) have been used in numerous consumer products and may enter the soil through the land application of biosolids. However, little is known about the relationship between Ag NP exposure and their bioavailability for soil organisms. This study aims at comparing the uptake and elimination kinetics of Ag upon exposures to different Ag forms (NPs and ionic Ag (as AgNO3)) in the isopod Porcellionides pruinosus. Isopods were exposed to contaminated Lufa 2.2 soil or alder leaves as food. Uptake and elimination rate constants for soil exposure did not significantly differ between Ag NPs and ionic Ag at 30 and 60 mg Ag/kg. For dietary exposure, the uptake rate constant was up to 5 times higher for Ag NPs than for AgNO3, but this was related to feeding activity and exposure concentrations, while no difference in the elimination rate constants was found. When comparing both routes, dietary exposure resulted in lower Ag uptake rate constants but elimination rate constants did not differ. A fast Ag uptake was observed from both routes and most of the Ag taken up seemed not to be eliminated. Synchrotron X-ray fluorescence showed Ag in the S-cells of the hepatopancreas, thus supporting the observations from the kinetic experiment (i.e. low elimination). In addition, our results show that isopods have an extremely high Ag accumulation capacity, suggesting the presence of an efficient Ag storage compartment.

  2. Evidence for surface Ag + complexes as the SERS-active sites on Ag electrodes

    NASA Astrophysics Data System (ADS)

    Watanabe, T.; Kawanami, O.; Honda, K.; Pettinger, B.

    1983-12-01

    Evidence is given that SERS-active sites at Ag electrodes are associated with Ag + ions, forming sparingly soluble surface complexes with ligands such as pyridine molecules and halide ions. Such surface Ag + complexes contribute a factor of >800 to the overall (10 7-fold) enhancement, possibly via a resonance Raman effect.

  3. Single step electrochemical synthesis of hydrophilic/hydrophobic Ag5 and Ag6 blue luminescent clusters.

    PubMed

    Santiago González, Beatriz; Blanco, M C; López-Quintela, M Arturo

    2012-12-21

    Well-defined Ag(5) and Ag(6) dodecanethiol/tetrabutyl ammonium-protected clusters were prepared by a one-pot electrochemical method. Ag clusters show bright and photostable emissions. The presence of a dual capping renders the silver clusters soluble in both organic and aqueous solvents.

  4. 78 FR 30965 - AG Valley Railroad, LLC-Operation Exemption-Ag Valley Holdings, LLC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-23

    ... Surface Transportation Board AG Valley Railroad, LLC--Operation Exemption--Ag Valley Holdings, LLC AG... original and 10 copies of all pleadings, referring to Docket No. FD 35736, must be filed with the Surface.... Board decisions and notices are available on our Web site at www.stb.dot.gov . Decided: May 20, 2013....

  5. Fractional telegrapher's equation from fractional persistent random walks

    NASA Astrophysics Data System (ADS)

    Masoliver, Jaume

    2016-05-01

    We generalize the telegrapher's equation to allow for anomalous transport. We derive the space-time fractional telegrapher's equation using the formalism of the persistent random walk in continuous time. We also obtain the characteristic function of the space-time fractional process and study some particular cases and asymptotic approximations. Similarly to the ordinary telegrapher's equation, the time-fractional equation also presents distinct behaviors for different time scales. Specifically, transitions between different subdiffusive regimes or from superdiffusion to subdiffusion are shown by the fractional equation as time progresses.

  6. Fractional telegrapher's equation from fractional persistent random walks.

    PubMed

    Masoliver, Jaume

    2016-05-01

    We generalize the telegrapher's equation to allow for anomalous transport. We derive the space-time fractional telegrapher's equation using the formalism of the persistent random walk in continuous time. We also obtain the characteristic function of the space-time fractional process and study some particular cases and asymptotic approximations. Similarly to the ordinary telegrapher's equation, the time-fractional equation also presents distinct behaviors for different time scales. Specifically, transitions between different subdiffusive regimes or from superdiffusion to subdiffusion are shown by the fractional equation as time progresses. PMID:27300830

  7. Progress with the AGS Booster

    SciTech Connect

    Weng, W.T.

    1988-01-01

    Rare K-decay, neutrino and heavy ion physics demands that a rapid- cycling high vacuum and high intensity Booster be built for the AGS at Brookhaven. For each mode of operation there are corresponding accelerator physics and design issues needing special attention. Problems pertinent to any single mode of operation have been encountered and solved before, but putting high intensity proton requirements and high vacuum heavy ion requirements into one machine demands careful design considerations and decisions. The lattice design and magnet characteristics will be briefly reviewed. Major design issues will be discussed and design choices explained. Finally, the construction status and schedule will be presented. 6 refs., 6 figs.

  8. Hypernuclear research at the AGS

    SciTech Connect

    Chrien, R.E.

    1984-01-01

    Although the field of hypernuclear research is over 30 years old, progress in exploring the detailed behavior of hypernuclei has been slow. This fact is due mainly to the technical problems of producing and studying these strange objects. Indeed each step in the improvement of technique has been accompanied by a breakthrough in our understanding of this fascinating subject. In this paper, the aim is to describe the evolution of hypernuclear research, stressing especially the contributions of the program based on the Brookhaven AGS. 23 references, 17 figures, 1 table.

  9. Effect of Mg or Ag addition on the evaporation field of Al.

    PubMed

    Aruga, Yasuhiro; Nako, Hidenori; Tsuneishi, Hidemasa; Hasegawa, Yuki; Tao, Hiroaki; Ichihara, Chikara; Serizawa, Ai

    2013-09-01

    It is known that the distribution of the charge-states as well as the evaporation field shift to higher values as the specimen temperature is decreased at a constant rate of evaporation. This study has explored the effect of Mg or Ag addition on the evaporation field of Al in terms of the charge state distribution of the field evaporated Al ions. The fractional abundance of Al(2+) ions with respect to the total Al ions in Al-Mg alloy is lower than that in pure Al, whereas it shows higher level in the Al-Ag alloy at lower temperatures. The temperature dependence of the fractional abundance of Al(2+) ions has been also confirmed, suggesting that Al atoms in the Al-Mg alloy need lower evaporation field, while higher field is necessary to evaporate Al atoms in the Al-Ag alloy, compared with pure Al. This tendency is in agreement with that of the evaporation fields estimated theoretically by means of measurements of the work function and calculations of the binding energy of the pure Al, Al-Mg and Al-Ag alloys.

  10. Method development for VOST Fractionator

    SciTech Connect

    St. Germain Wickham, M.E.; Cummins, S.B.; Radolovich, G. )

    1994-01-01

    A VOST Fractionator was designed and tested to fractionate an original VOST sample into two samples: one large and one small sample. The device allows for quantitation of high levels of compounds in the small fraction and trace levels in the large fraction. Several preliminary validation samples were prepared, split, and analyzed to test the feasibility of the VOST Fractionator. These validation samples contained 40,000 ng of three terpene compounds and 100 ng of 42 other volatile target analytes. Analyte recoveries ranged from 70 to 130 percent, except for five water-soluble compounds. Recovery for the terpene compounds was 110 to 118 percent. Precision for triplicate spiked samples was less than 30 percent relative standard deviation (%RSD) for most compounds. Results indicate that the VOST Fractionator accurately splits the sample and allows quantitation of extremely high levels of compounds without sacrificing sensitivity for trace compounds. 3 refs., 1 fig., 3 tabs.

  11. Nonbiological fractionation of iron isotopes

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Roe, J. E.; Barling, J.; Nealson, K. H.

    2000-01-01

    Laboratory experiments demonstrate that iron isotopes can be chemically fractionated in the absence of biology. Isotopic variations comparable to those seen during microbially mediated reduction of ferrihydrite are observed. Fractionation may occur in aqueous solution during equilibration between inorganic iron complexes. These findings provide insight into the mechanisms of iron isotope fractionation and suggest that nonbiological processes may contribute to iron isotope variations observed in sediments.

  12. Trigonometric Integrals via Partial Fractions

    ERIC Educational Resources Information Center

    Chen, H.; Fulford, M.

    2005-01-01

    Parametric differentiation is used to derive the partial fractions decompositions of certain rational functions. Those decompositions enable us to integrate some new combinations of trigonometric functions.

  13. Optimal synthesis and characterization of Ag nanofluids by electrical explosion of wires in liquids

    PubMed Central

    2011-01-01

    Silver nanoparticles were produced by electrical explosion of wires in liquids with no additive. In this study, we optimized the fabrication method and examined the effects of manufacturing process parameters. Morphology and size of the Ag nanoparticles were determined using transmission electron microscopy and field-emission scanning electron microscopy. Size and zeta potential were analyzed using dynamic light scattering. A response optimization technique showed that optimal conditions were achieved when capacitance was 30 μF, wire length was 38 mm, liquid volume was 500 mL, and the liquid type was deionized water. The average Ag nanoparticle size in water was 118.9 nm and the zeta potential was -42.5 mV. The critical heat flux of the 0.001-vol.% Ag nanofluid was higher than pure water. PMID:21711757

  14. Photon emission intensities in the decay of 108mAg and 110mAg.

    PubMed

    Ferreux, L; Lépy, M-C; Bé, M-M; Isnard, H; Lourenço, V

    2014-05-01

    This study focuses on two radioisotopes of silver, (108m)Ag and (110m)Ag, characterized by a complex decay scheme. Each isotope has two disintegration modes, the isomeric transition leading to the daughter isotope ((108)Ag and (110)Ag, respectively) with a short half-life. The radioactive solution was obtained by neutron activation on silver powder enriched in (109)Ag. Gamma-spectrometry was carried out using a calibrated high purity germanium detector. The main relative photon emission intensities for both radionuclides were obtained and compared with previously published values.

  15. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    SciTech Connect

    Singh, Anamika; Dutta, Dimple P.; Ballal, A.; Tyagi, A.K.; Fulekar, M.H.

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  16. Effects of soil and dietary exposures to Ag nanoparticles and AgNO₃ in the terrestrial isopod Porcellionides pruinosus.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Jurkschat, Kerstin; Soares, Amadeu M V M; Loureiro, Susana

    2015-10-01

    The effects of Ag-NPs and AgNO3 on the isopod Porcellionides pruinosus were determined upon soil and dietary exposures. Isopods avoided Ag in soil, with EC50 values of ∼16.0 and 14.0 mg Ag/kg for Ag-NPs and AgNO3, respectively. Feeding inhibition tests in soil showed EC50s for effects on consumption ratio of 127 and 56.7 mg Ag/kg, respectively. Although similar EC50s for effects on biomass were observed for nanoparticulate and ionic Ag (114 and 120 mg Ag/kg dry soil, respectively), at higher concentrations greater biomass loss was found for AgNO3. Upon dietary exposure, AgNO3 was more toxic, with EC50 for effects on biomass change being >1500 and 233 mg Ag/kg for Ag-NPs and AgNO3, respectively. The difference in toxicity between Ag-NPs and AgNO3 could not be explained from Ag body concentrations. This suggests that the relation between toxicity and bioavailability of Ag-NPs differs from that of ionic Ag in soils.

  17. Si/Ag composite with bimodal micro-nano porous structure as a high-performance anode for Li-ion batteries.

    PubMed

    Hao, Qin; Zhao, Dianyun; Duan, Huimei; Zhou, Qiuxia; Xu, Caixia

    2015-03-12

    A one-step dealloying method is employed to conveniently fabricate a bimodal porous (BP) Si/Ag composite in high throughput under mild conditions. Upon dealloying the carefully designed SiAgAl ternary alloy in HCl solution at room temperature, the obtained Si/Ag composite has a uniform bicontinuous porous structure in three dimensions with micro-nano bimodal pore size distribution. Compared with the traditional preparation methods for porous Si and Si-based composites, this dealloying route is easily operated and environmentally benign. More importantly, it is convenient to realize the controllable components and uniform distribution of Si and Ag in the product. Owing to the rich porosity of the unique BP structure and the incorporation of highly conductive Ag, the as-made Si/Ag composite possesses the improved conductivity and alleviated volume changes of the Si network during repeated charging and discharging. As expected, the BP Si/Ag anode exhibits high capacity, excellent cycling reversibility, long cycling life and good rate capability for lithium storage. When the current rate is up to 1 A g(-1), BP Si/Ag can deliver a stable reversible capacity above 1000 mA h g(-1), and exhibits a capacity retention of up to 89.2% against the highest capacity after 200 cycles. With the advantages of unique performance and easy preparation, the BP Si/Ag composite holds great application potential as an advanced anode material for Li-ion batteries.

  18. Tribological properties of ag-based amphiphiles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most ag-based materials are amphiphilic because they comprise polar and non-polar groups within the same molecule. One of the major categories of amphiphilic ag-based materials are seed oils, which are actively investigated as substitutes for petroleum in a wide variety of consumer and industrial a...

  19. AgRISTARS documents tracking list report

    NASA Technical Reports Server (NTRS)

    Hawkins, J. L.

    1983-01-01

    A quarterly listing of documents issued and placed in the AgRISTARS tracking system is provided. The technical publications are arranged by type of documents. The reference AgRISTARS document number, title and date of publication, the issuing organization, and the National Technical Information Service reference number is given.

  20. The AGS synchrotron with four helical magnets

    SciTech Connect

    Tsoupas N.; Huang, H.; Roser, T.; MacKay, W.W.; Trbojevic, D.

    2012-05-20

    The idea of using two partial helical magnets was applied successfully to the AGS synchrotron to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. The placement of four helical magnets in the AGS ring provides many advantages over the present setup of the AGS which uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides for a larger 'spin tune gap', which allows the vertical and horizontal tunes to be placed, and prevent the horizontal and vertical intrinsic spin resonances of the AGS to occur during the acceleration cycle. Although the same spin gap can be obtained with a single or two partial helices, the required high field strength of a single helix makes its use impractical, and that of the double helix rather difficult. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and compare these results with the present setup of the AGS that uses two partial helical magnets.

  1. Recent hypernuclear research at the Brookhaven AGS

    SciTech Connect

    Chrien, R.E.

    1985-01-01

    Recent AGS experiments contributing to our knowledge of hypernuclei are reviewed. These experiments have suggested new areas of research on hypernuclei. With the proper beam line facilities, the AGS will be able to perform experiments in these areas and provide a transition to the future era of ''kaon factories''. 20 refs., 14 figs.

  2. Label-Free Detection of Ag+ Based on Gold Nanoparticles and Ag+-Specific DNA.

    PubMed

    Pu, Wendan; Zhao, Zhao; Wu, Liping; Liu, Yue; Zhao, Huawen

    2015-08-01

    A sensitive label-free method was presented for the determination of silver ion (Ag+) in this paper. Cytosine-rich DNA (C-DNA) was used as Ag+ specific DNA. Without Ag+ in the solution, fluorescence of fluorescein (FAM) is quenched by C-DNA stabilized gold nanoparticles (AuNPs) in high salt environment. When Ag+ is present in the solution, however, Ag+-mediated cytosine-Ag+-cytosine (C-Ag+-C) base pairs induced the C-DNA folding into a hairpin structure, which can not stabilize AuNPs in high salt environment, thus causing AuNPs aggregation. After centrifugation to remove the aggregated AuNPs, the quenching ability of the supernatant for FAM is decreased and the fluorescence intensity of solution increases with increasing the Ag+ concentration. Due to the highly specific interaction of the C-DNA towards Ag+ and the strong fluorescent quenching ability of AuNPs for FAM, the method has high selectivity and sensitivity for Ag+. Under the optimal conditions, the fluorescence intensity at 515 nm increased linearly with the concentration of Ag+ ranging from 15 nM to 700 nM, and the detection limit was determined as 6 nM based on 3 σ/slope. This method is simple, sensitive, and may be applied to other detection systems by selecting the appropriate DNA sequences. PMID:26369112

  3. Raman scattering enhanced within the plasmonic gap between an isolated Ag triangular nanoplate and Ag film

    NASA Astrophysics Data System (ADS)

    Li, Kuanguo; Jiang, Kang; Zhang, Lan; Wang, Yong; Mao, Lei; Zeng, Jie; Lu, Yonghua; Wang, Pei

    2016-04-01

    Enhanced electromagnetic field in the tiny gaps between metallic nanostructures holds great promise in optical applications. Herein, we report novel out-of-plane nanogaps composed of micrometer-sized Ag triangular nanoplates (AgTN) on Ag films. Notably, the new coupled plasmonic structure can dramatically enhance the surface-enhanced Raman scattering (SERS) by visible laser excitation, although the micrometer-sized AgTN has localized plasmon resonance at infrared wavelength. This enhancement is derived from the gap plasmon polariton between the AgTN and Ag film, which is excited via the antenna effect of the corner and edge of the AgTN. Systematic SERS studies indicated that the plasmon enhancement was on the order of corner > edge > face. These results were further verified by theoretical simulations. Our device paves the way for rational design of sensitive SERS substrates by judiciously choosing appropriate nanoparticles and optimizing the gap distance.

  4. Atomic-level observation of Ag-ion hopping motion in AgI

    NASA Astrophysics Data System (ADS)

    Sato, W.; Komatsuda, S.; Mizuuchi, R.; Irioka, N.; Kawata, S.; Ohkubo, Y.

    2015-04-01

    Applicability of the 111mCd(→111Cd) and 111In(→111Cd) probes to the study of dynamics in polycrystalline silver iodide (AgI) was examined by means of the time-differential perturbed angular correlation technique. It was found that the 111mCd(→111Cd) probe occupies a unique site in γ-AgI and exhibits nuclear relaxation caused by dynamic perturbation arising from Ag + hopping motion in α-AgI; while the residential sites of 111In(→111Cd) vary, suggesting that 111In ions can not settle themselves in a fixed site in the AgI crystal structure. We here demonstrate that 111mCd(→111Cd) can be a potential nucleus to probe the Ag +-ion dynamic motion in α-AgI.

  5. AgPO2F2 and Ag9(PO2F2)14: the first Ag(i) and Ag(i)/Ag(ii) difluorophosphates with complex crystal structures.

    PubMed

    Malinowski, Przemysław J; Kurzydłowski, Dominik; Grochala, Wojciech

    2015-12-01

    The reaction of AgF2 with P2O3F4 yields a mixed valence Ag(I)/Ag(II) difluorophosphate salt with AgAg(PO2F2)14 stoichiometry - the first Ag(ii)-PO2F2 system known. This highly moisture sensitive brown solid is thermally stable up to 120 °C, which points at further feasible extension of the chemistry of Ag(ii)-PO2F2 systems. The crystal structure shows a very complex bonding pattern, comprising of polymeric Ag(PO2F2)14(4-) anions and two types of Ag(I) cations. One particular Ag(II) site present in the crystal structure of Ag9(PO2F2)14 is the first known example of square pyramidal penta-coordinated Ag(ii) in an oxo-ligand environment. Ag(i)PO2F2 - the product of the thermal decomposition of Ag9(PO2F2)14 - has also been characterized by thermal analysis, IR spectroscopy and X-ray powder diffraction. It has a complicated crystal structure as well, which consists of infinite 1D [Ag(I)O4/2] chains which are linked to more complex 3D structures via OPO bridges. The PO2F2(-) anions bind to cations in both compounds as bidentate oxo-ligands. The terminal F atoms tend to point inside the van der Waals cavities in the crystal structure of both compounds. All important structural details of both title compounds were corroborated by DFT calculations. PMID:26200921

  6. Hepatoprotective and antiviral efficacy of Acacia mellifera leaves fractions against hepatitis B virus.

    PubMed

    Arbab, Ahmed H; Parvez, Mohammad K; Al-Dosari, Mohammed S; Al-Rehaily, Adnan J; Al-Sohaibani, Mohammed; Zaroug, Elwaleed E; AlSaid, Mansour S; Rafatullah, Syed

    2015-01-01

    The present study investigated the hepatoprotective and anti-HBV efficacy of Acacia mellifera (AM) leaves extracts. The crude ethanolic-extract, including organic and aqueous fractions, were tested for cytotoxicity on HepG2 and HepG2.2.15 cells (IC50=684 μg/mL). Of these, the ethyl acetate and aqueous fractions showed the most promising, dose-dependent hepatoprotection in DCFH-toxicated cells at 48 h. In CCl4-injured rats, oral administration of AM ethanol extract (250 and 500 mg/kg·bw) for three weeks significantly normalized the sera aminotransferases, alkaline phosphatase, bilirubin, cholesterol, triglycerides, and lipoprotein levels and elevated tissue nonprotein sulphydryl and total protein. The histopathology of dissected livers also revealed that AM cured the tissue lesions. The phytochemical screening of the fractions showed presence of alkaloids, flavonoids, tannins, sterols, and saponins. Further, anti-HBV potential of the fractions was evaluated on HepG2.2.15 cells. Of these, the n-butanol and aqueous fractions exhibited the best inhibitory effects on HBsAg and HBeAg expressions in dose- and time-dependent manner. Taken together, while the ethyl acetate and aqueous fractions exhibited the most promising antioxidant/hepatoprotective and anti-HBV activity, respectively, the n-butanol partition showed both activities. Therefore, the therapeutic potential of AM extracts warrants further isolation of the active principle(s) and its phytochemical as well as biological studies.

  7. Nootropic Effects of Filipendula Vulgaris Moench Water Extract Fractions.

    PubMed

    Shilova, I V; Suslov, N I; Amelchenko, V P

    2015-07-01

    Nootropic activity of water extract fractions from aerial parts of Filipendula vulgaris Moench was demonstrated on the models of hermetic volume hypoxia, conditioned passive avoidance response, open field test, and forced swimming with a load. The fractions stimulated hypoxic resistance, normalized orientation and exploratory behavior, improved conditioned response reproduction during testing after hypoxic injury, and increased exercise tolerance. Fractionation of the extract led to dissociation of the effect components, which suggests that individual constituents have specific characteristics. Ethylacetate fraction exhibited most pronounced nootropic activity and was superior to plant extract by some characteristics. The detected effects seemed to be caused by modulation of the hippocampus activity the under the effects of phenol and triterpene compounds. PMID:26210209

  8. Nootropic Effects of Filipendula Vulgaris Moench Water Extract Fractions.

    PubMed

    Shilova, I V; Suslov, N I; Amelchenko, V P

    2015-07-01

    Nootropic activity of water extract fractions from aerial parts of Filipendula vulgaris Moench was demonstrated on the models of hermetic volume hypoxia, conditioned passive avoidance response, open field test, and forced swimming with a load. The fractions stimulated hypoxic resistance, normalized orientation and exploratory behavior, improved conditioned response reproduction during testing after hypoxic injury, and increased exercise tolerance. Fractionation of the extract led to dissociation of the effect components, which suggests that individual constituents have specific characteristics. Ethylacetate fraction exhibited most pronounced nootropic activity and was superior to plant extract by some characteristics. The detected effects seemed to be caused by modulation of the hippocampus activity the under the effects of phenol and triterpene compounds.

  9. Antibacterial biodegradable Mg-Ag alloys.

    PubMed

    Tie, D; Feyerabend, F; Müller, W D; Schade, R; Liefeith, K; Kainer, K U; Willumeit, R

    2013-06-16

    The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4) and aging (T6) heat treatment. The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH)₂ and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7), revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231) and Staphylococcus epidermidis (DSMZ 3269), and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

  10. Rational Exponentials and Continued Fractions

    ERIC Educational Resources Information Center

    Denny, J. K.

    2012-01-01

    Using continued fraction expansions, we can approximate constants, such as pi and e, using an appropriate integer n raised to the power x[superscript 1/x], x a suitable rational. We review continued fractions and give an algorithm for producing these approximations.

  11. Multiple fractional Fourier transform holography

    NASA Astrophysics Data System (ADS)

    Zeng, Yangsu; Zhang, Yixiao; Gao, Feng; Gao, Fuhua; Huang, Xiaoyang; Guo, Yongkang

    2002-04-01

    In this paper, we introduce the recording and reconstruction theories of the multiple fractional Fourier transform hologram (M-FRTH). We fabricated a multiple fractional Fourier transform hologram, and obtained satisfying reconstruction results. The experimental result shows that the M-FRTH has a high anti-counterfeiting capacity and can be used in the fabrication of the trademark, ID, and the notes.

  12. Fractionation process for petroleum wax

    SciTech Connect

    Jones, R.L.; Mitchael, M.R.; Krenowicz, R.A.; Southard, W.M.

    1991-07-16

    This patent describes a process which comprises separating a petroleum wax into a lower boiling wax fraction of a narrow melting range and a higher boiling wax fraction of wider melting range by subjecting the petroleum wax to distillation in a wiped film evaporator.

  13. Understanding Magnitudes to Understand Fractions

    ERIC Educational Resources Information Center

    Gabriel, Florence

    2016-01-01

    Fractions are known to be difficult to learn and difficult to teach, yet they are vital for students to have access to further mathematical concepts. This article uses evidence to support teachers employing teaching methods that focus on the conceptual understanding of the magnitude of fractions.

  14. Investigations on Multiplication of Fractions.

    ERIC Educational Resources Information Center

    Sai, Khoo Phon; Inder, Walter R. D.

    1984-01-01

    Three different models with continuous materials, discontinuous materials, and number lines were used to study the operation concept in six investigations on multiplication with fractions with pupils aged 11-12 in a Penang International School. All approaches could be understood by pupils, but they preferred the area and fractional models. (MNS)

  15. Progress in Solving the Elusive Ag Transport Mechanism in TRISO Coated Particles: What is new?

    SciTech Connect

    Isabella Van Rooyen

    2014-10-01

    The TRISO particle for HTRs has been developed to an advanced state where the coating withstands internal gas pressures and retains fission products during irradiation and under postulated accidents. However, one exception is Ag that has been found to be released from high quality TRISO coated particles when irradiated and can also during high temperature accident heating tests. Although out- of- pile laboratory tests have never hither to been able to demonstrate a diffusion process of Ag in SiC, effective diffusion coefficients have been derived to successfully reproduce measured Ag-110m releases from irradiated HTR fuel elements, compacts and TRISO particles It was found that silver transport through SiC does not proceed via bulk volume diffusion. Presently grain boundary diffusion that may be irradiation enhanced either by neutron bombardment or by the presence of fission products such as Pd, are being investigated. Recent studies of irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), transmission kukuchi diffraction (TKD) patterns and high resolution transmission electron microscopy (HRTEM) have been used to further the understanding of Ag transport through TRISO particles. No silver was observed in SiC grains, but Ag was identified at triple-points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in some of the very same triple junctions, but this could be related to silver behavior as Ag-110m decays to Cd-110. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries and in most SiC grain boundaries and the potential role of Pd in the transport of Ag will be discussed.

  16. Nucleation and Growth of Cu-Al Intermetallics in Al-Modified Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys

    NASA Astrophysics Data System (ADS)

    Reeve, Kathlene N.; Anderson, Iver E.; Handwerker, Carol A.

    2015-03-01

    Lead-free solder alloys Sn-Cu (SC) and Sn-Ag-Cu (SAC) are widely used by the microelectronics industry, but enhanced control of the microstructure is needed to improve solder performance. For such control, nucleation and stability of Cu-Al intermetallic compound (IMC) solidification catalysts were investigated by variation of the Cu (0.7-3.0 wt.%) and Al (0.0-0.4 wt.%) content of SC + Al and SAC + Al alloys, and of SAC + Al ball-grid array (BGA) solder joints. All of the Al-modified alloys produced Cu-Al IMC particles with different morphologies and phases (occasionally non-equilibrium phases). A trend of increasing Cu-Al IMC volume fraction with increasing Al content was established. Because of solidification of non-equilibrium phases in wire alloy structures, differential scanning calorimetry (DSC) experiments revealed delayed, non-equilibrium melting at high temperatures related to quenched-in Cu-Al phases; a final liquidus of 960-1200°C was recorded. During cooling from 1200°C, the DSC samples had the solidification behavior expected from thermodynamic equilibrium calculations. Solidification of the ternary alloys commenced with formation of ternary β and Cu-Al δ phases at 450-550°C; this was followed by β-Sn, and, finally, Cu6Sn5 and Cu-Al γ1. Because of the presence of the retained, high-temperature phases in the alloys, particle size and volume fraction of the room temperature Cu-Al IMC phases were observed to increase when the alloy casting temperature was reduced from 1200°C to 800°C, even though both temperatures are above the calculated liquidus temperature of the alloys. Preliminary electron backscatter diffraction results seemed to show Sn grain refinement in the SAC + Al BGA alloy.

  17. Radiating subdispersive fractional optical solitons

    SciTech Connect

    Fujioka, J. Espinosa, A.; Rodríguez, R. F.; Malomed, B. A.

    2014-09-01

    It was recently found [Fujioka et al., Phys. Lett. A 374, 1126 (2010)] that the propagation of solitary waves can be described by a fractional extension of the nonlinear Schrödinger (NLS) equation which involves a temporal fractional derivative (TFD) of order α > 2. In the present paper, we show that there is also another fractional extension of the NLS equation which contains a TFD with α < 2, and in this case, the new equation describes the propagation of radiating solitons. We show that the emission of the radiation (when α < 2) is explained by resonances at various frequencies between the pulses and the linear modes of the system. It is found that the new fractional NLS equation can be derived from a suitable Lagrangian density, and a fractional Noether's theorem can be applied to it, thus predicting the conservation of the Hamiltonian, momentum and energy.

  18. Structure, dynamics, and electronic structure of liquid Ag-Se alloys investigated by ab initio simulation

    NASA Astrophysics Data System (ADS)

    Kirchhoff, F.; Holender, J. M.; Gillan, M. J.

    1996-07-01

    Ab initio molecular-dynamics simulations have been used to investigate the structure, dynamics, and electronic properties of the liquid alloy Ag1-xSex at 1350 K and at the three compositions x=0.33, 0.42, and 0.65. To provide a point of reference, calculations are also presented for the equilibrium structure and the electronic structure of the α-Ag2Se crystal. The calculations are based on density-functional theory in the local-density approximation and on the pseudopotential plane-wave method. For the solid, we find excellent agreement with experiment for the equilibrium lattice parameters and the atomic coordinates of the 12-atom orthorhombic unit cell, and we present an analysis of the electronic density of states and density distribution. The reliability of the liquid simulations is confirmed by detailed comparisons with very recent neutron-diffraction results for the partial structure factors and radial distribution functions (RDF) of the stoichiometric liquid Ag2Se. Comparison with the predictions of an empirical interaction model due to Rino et al. is also given for l-Ag2Se. The ab initio simulations show a dramatic change of the Se-Se RDF with increasing Se content. This change is due to the formation of Se clusters bound by covalent bonds, the Se-Se bond length being almost the same as in pure c-Se and l-Se. The clusters are predominantly chainlike, but for higher x there is a significant fraction of threefold coordinated Se atoms. It is shown that the equilibrium fractions of Se present as isolated atoms and in clusters can be understood on a simple charge-balance model based on an ionic interpretation. The Ag diffusion coefficient in the simulated stoichiometric liquid is consistent with experimental values measured in the high-temperature superionic solid. The Ag and Se diffusion coefficients both increase with Se content, in spite of the Se clustering. An analysis of the Se-Se bond dynamics reveals surprisingly short bond lifetimes of less than 1 ps

  19. Free volume in contact lens polymers

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Eftekhari, Abe; Upchurch, Billy T.; Burns, Karen S.

    1990-01-01

    We have measured the free volume and gas permeability in several contact lens specimens as part of a Space Commercialization Program. Free volume was measured using positron lifetime spectroscopy, while permeability for O2, N2, and CO2 gases was measured using mass spectrometry and polarography. It has been noted that permeability for all gases increases with the mean free volume cell size in the test samples. As might be expected, the specimens with the highest free volume fraction also exhibit the lowest Rockwell Hardness Number. An interesting corollary of this study is the finding that the presence of fluorine atoms in the lens chemical structure inhibits filling up of their free volume cells. This is expected to allow the lenses to breathe freely while in actual use.

  20. Ag(I)-binding to phytochelatins.

    PubMed

    Mehra, R K; Tran, K; Scott, G W; Mulchandani, P; Saini, S S

    1996-02-01

    Phytochelatins (PCs) are glutathione-derived peptides with the general structure (gamma-Glu-Cys)nGly, where n varies from 2 to 11. A variety of metal ions such as Cu(II), Cd(II), Pb(II), Zn(II), and Ag(I) induce PC synthesis in plants and some yeasts. It has generally been assumed that the inducer metals also bind PCs. However, very little information is available on the binding of metals other than Cu(I) and Cd(II) to PCs. In this paper, we describe the Ag(I)-binding characteristics of PCs with the structure (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly. The Ag(I)-binding stoichiometries of these three peptides were determined by (i) UV/VIS spectrophotometry, (ii) luminescence spectroscopy at 77 K, and (iii) reverse-phase HPLC. The three techniques yielded similar results. ApoPCs exhibit featureless absorption in the 220-340 nm range. The binding of Ag(I) to PCs induced the appearance of specific absorption shoulders. The titration end point was indicated by the flattening of the characteristic absorption shoulders. Similarly, luminescence at 77 K due to Ag(I)-thiolate clusters increased with the addition of graded Ag(I) equivalents. The luminescence declined when Ag(I) equivalents in excess of the saturating amounts were added to the peptides. At neutral pH, (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly bind 1.0, 1.5, and 4.0 equivalents of Ag(I), respectively. The Ag(I)-binding capacity of (gamma-Glu-Cys)2Gly and (gamma-Glu-Cys)3Gly was increased at pH 5.0 and below so that Ag(I)/-SH ratio approached 1.0. A similar pH-dependent binding of Ag(I) to glutathione was also observed. The increased Ag(I)-binding to PCs at lower pH is of physiological significance as these peptides accumulate in acidic vacuoles. We also report lifetime data on Ag(I)-PCs. The relatively long decay-times (approximately 0.1-0.3 msec) accompanied with a large Stokes shift in the emission band are indicative of spin-forbidden phosphorescence. PMID

  1. Digestion kinetics of carbohydrate fractions of citrus by-products

    PubMed Central

    Lashkari, Saman; Taghizadeh, Akbar

    2015-01-01

    The present experiment was carried out to determine the digestion kinetics of carbohydrate fractions of citrus by-products. Grapefruit pulp (GP), lemon pulp (LE), lime pulp (LI) and orange pulp (OP) were the test feed. Digestion kinetic of whole citrus by-products and neutral detergent fiber (NDF) fraction and acid detergent fiber (ADF) fractions of citrus by-products were measured using the in vitro gas production technique. Fermentation kinetics of the neutral detergent soluble carbohydrates (NDSC) fraction and hemicelluloses were calculated using a curve subtraction. The fermentation rate of whole was the highest for the LE (p < 0.05). For all citrus by-products lag time was longer for hemicellulose than other carbohydrate fractions. There was no significant difference among potential gas production (A) volumes of whole test feeds (p < 0.16). Dry matter (DM) digestibility contents of LE and LI were the highest (p < 0.02). The NDF digestibility was the highest (p < 0.05) in LI and GP, while the lowest (p < 0.03) values of ADF digestibility were observed in LI and LE. According to the results of the present study, carbohydrate fractions of citrus by-products have high potential for degradability. It could also be concluded that carbohydrate fractions of citrus by-products have remarkable difference in digestion kinetics and digestive behavior. PMID:25992250

  2. Spectroscopic Study on Eu3+ Doped Borate Glasses Containing Ag Nanoparticles and Ag Aggregates.

    PubMed

    Fu, Shaobo; Zheng, Hui; Zhang, Jinsu; Li, Xiangping; Sun, Jiashi; Hua, Ruinian; Dong, Bin; Xia, Haiping; Chen, Baojiu

    2015-01-01

    Transparent Eu(3+)-doped borate glasses containing Ag nanoparticles and Ag aggregates with composition (40 - x) CaO-59.5B2O3-0.5Eu2O3-xAgNO3 were prepared by a simple one-step melt-quenching technique. The X-ray diffraction (XRD) patterns of the glasses reveal amorphous structural properties and no diffraction peaks belonging to metal Ag particles. Ag particles and Ag aggregates were observed from the absorption spectra. Effective energy transfers from the Ag aggregates to the Eu3+ ions were observed in the excitation spectra from monitoring the intrinsic emission of Eu3+x .5D0 --> 7F2. The glasses with higher Ag content can be effectively excited by light in a wide wavelength region, indicating that these glasses have potential application in the solid state lighting driven by semiconductor light emitting diodes (LEDs). The emission spectra of the samples with higher Ag contents exhibit plenteous spectral components covering the full visible region from violet to red, thus indicating that these glass materials possess an excellent and tunable color rendering index. The color coordinates for all the glass samples were calculated by using the intensity-corrected emission spectra and the standard data issued by the CIE (Commission International de l' Eclairage) in 1931. It was found that the color coordinates for most samples with higher Ag contents fall into the white region in the color space. PMID:26328363

  3. Study of antibacterial activity of Ag and Ag2CO3 nanoparticles stabilized over montmorillonite

    NASA Astrophysics Data System (ADS)

    Sohrabnezhad, Sh.; Pourahmad, A.; Mehdipour Moghaddam, M. J.; Sadeghi, A.

    2015-02-01

    Silver carbonate and silver nanoparticles (NPs) over of stabilizer montmorillonite (MMT) have been synthesized in aqueous and polyol solvent, respectively. Dispersions of silver nanoparticles have been prepared by the reduction of silver nitrate over of MMT in presence and absence of Na2CO3 compound in ethylene glycol. It was observed that montmorillonite was capable of stabilizing formed Ag nanoparticles through the reduction of Ag+ ions in ethylene glycol. Na2CO3 was used as carbonate source in synthesis of Ag2CO3 NPs in water solvent and also for controlling of Ag nanoparticles size in ethylene glycol medium. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The TEM images showed that Ag NPs size in presence Na2CO3 salts was smaller than without that. The results indicated intercalation of Ag and Ag2CO3 nanoparticles into the montmorillonite clay layers. The diffuse reflectance spectra exhibited a strong surface plasmon resonance (SPR) adsorption peak in the visible region, resulting from Ag nanoparticles. The antibacterial testing results showed that the Ag2CO3-MMT nanocomposite exhibited an antibacterial activity higher than Ag-MMT sample against Escherichia coli.

  4. Modeling nuclear volume isotope effects in crystals.

    PubMed

    Schauble, Edwin A

    2013-10-29

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from (119)Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.

  5. Modeling nuclear volume isotope effects in crystals

    PubMed Central

    Schauble, Edwin A.

    2013-01-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac–Hartree–Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor–crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium

  6. Modeling nuclear volume isotope effects in crystals

    NASA Astrophysics Data System (ADS)

    Schauble, Edwin A.

    2013-10-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.

  7. Evaluation of two new automated assays for hepatitis B virus surface antigen (HBsAg) detection: IMMULITE HBsAg and IMMULITE 2000 HBsAg.

    PubMed

    Weber, Bernard; Dengler, Thomas; Berger, Annemarie; Doerr, Hans Wilhelm; Rabenau, Holger

    2003-01-01

    In recent years the diagnostic industry has developed new automated immunoassays for the qualitative detection of hepatitis B virus (HBV) surface antigen (HBsAg) in serum and plasma samples that are performed on analyzers that permit a high-speed throughput, random access, and primary tube sampling. The aim of the present study was the evaluation of two new automated HBsAg screening assays, IMMULITE HBsAg and IMMULITE 2000 HBsAg, from Diagnostic Products Corporation. The new HBsAg assays were compared to well-established tests (Auszyme Monoclonal [overnight incubation, version B], IMx HBsAg, AxSYM HBsAg, and Prism HBsAg [all from Abbott] and Elecsys HBsAg [Roche Diagnostics]). In the evaluation were included seroconversion panels, sera from the acute and chronic phases of infection, dilution series of various HBsAg standards, HBV subtypes and S gene mutants. To challenge the specificity of the new assays, sera from HBsAg-negative blood donors, pregnant women, and dialysis and hospitalized patients and potentially cross-reactive samples were investigated. IMMULITE HBsAg and IMMULITE 2000 HBsAg, although not as sensitive as the Elecsys HBsAg assay, were equivalent to the AxSYM HBsAg assay and showed a higher sensitivity than the Auszyme Monoclonal B and IMx HBsAg systems for detection of acute infection in seroconversion panels. The specificities (100%) of both IMMULITE assays on unselected blood donors and potentially interfering samples were comparable to those of the alternative assays after repeated testing. In conclusion, the new IMMULITE HBsAg and IMMULITE 2000 HBsAg assays show a good sensitivity for HBsAg detection compared to other well-established tests. The specificity on repeatedly tested samples was equivalent to that of the alternative assays. The rapid turnaround time, primary tube sampling, and on-board dilution make it an interesting assay system for clinical laboratory diagnosis.

  8. Demonstration and partial characterization of 22-nm HBsAg and Dane particles of subtype HBsAg/ady.

    PubMed

    Hess, G; Shih, J W; Arnold, W; Gerin, J L; zum Büschenfelde, K H

    1979-09-01

    The present paper describes the demonstration of d, y, w, and r HBsAg determinants in one serum. It was shown that there are two populations of HBsAg particles: HBsAg/ad and HBsAg/ady. All complete Dane particles were of subtype HBsAg/ady. Further characterization of HBsAg/ady particles did not reveal morphologic differences when they were compared with HBsAg/ad and HBsAg/ay particles. An HBsAg/ady phenotype may be the result of a double infection with hepatitis B viruses or exchanges of DNA sequences that determine HBsAg/ay and HBsAg/ad to form a new genotype. PMID:89163

  9. Demonstration and partial characterization of 22-nm HBsAg and Dane particles of subtype HBsAg/ady.

    PubMed

    Hess, G; Shih, J W; Arnold, W; Gerin, J L; zum Büschenfelde, K H

    1979-09-01

    The present paper describes the demonstration of d, y, w, and r HBsAg determinants in one serum. It was shown that there are two populations of HBsAg particles: HBsAg/ad and HBsAg/ady. All complete Dane particles were of subtype HBsAg/ady. Further characterization of HBsAg/ady particles did not reveal morphologic differences when they were compared with HBsAg/ad and HBsAg/ay particles. An HBsAg/ady phenotype may be the result of a double infection with hepatitis B viruses or exchanges of DNA sequences that determine HBsAg/ay and HBsAg/ad to form a new genotype.

  10. Relationship between fractional calculus and fractional Fourier transform

    NASA Astrophysics Data System (ADS)

    Zhang, Yanshan; Zhang, Feng; Lu, Mingfeng

    2015-09-01

    The fractional calculus (FC) deals with integrals and derivatives of arbitrary (i.e., non-integer) order, and shares its origins with classical integral and differential calculus. The fractional Fourier transform (FRFT), which has been found having many applications in optics and other areas, is a generalization of the usual Fourier transform. The FC and the FRFT are two of the most interesting and useful fractional areas. In recent years, it appears many papers on the FC and FRFT, however, few of them discuss the connection of the two fractional areas. We study their relationship. The relational expression between them is deduced. The expectation of interdisciplinary cross fertilization is our motivation. For example, we can use the properties of the FC (non-locality, etc.) to solve the problem which is difficult to be solved by the FRFT in optical engineering; we can also through the physical meaning of the FRFT optical implementation to explain the physical meaning of the FC. The FC and FRFT approaches can be transposed each other in the two fractional areas. It makes that the success of the fractional methodology is unquestionable with a lot of applications, namely in nonlinear and complex system dynamics and image processing.

  11. Fractionally charged skyrmions in fractional quantum Hall effect

    DOE PAGES

    Balram, Ajit C.; Wurstbauer, U.; Wójs, A.; Pinczuk, A.; Jain, J. K.

    2015-11-26

    The fractional quantum Hall effect has inspired searches for exotic emergent topological particles, such as fractionally charged excitations, composite fermions, abelian and nonabelian anyons and Majorana fermions. Fractionally charged skyrmions, which support both topological charge and topological vortex-like spin structure, have also been predicted to occur in the vicinity of 1/3 filling of the lowest Landau level. The fractional skyrmions, however, are anticipated to be exceedingly fragile, suppressed by very small Zeeman energies. Here we show that, slightly away from 1/3 filling, the smallest manifestations of the fractional skyrmion exist in the excitation spectrum for a broad range of Zeemanmore » energies, and appear in resonant inelastic light scattering experiments as well-defined resonances slightly below the long wavelength spin wave mode. The spectroscopy of these exotic bound states serves as a sensitive tool for investigating the residual interaction between composite fermions, responsible for delicate new fractional quantum Hall states in this filling factor region.« less

  12. Fractional trajectories: Decorrelation versus friction

    NASA Astrophysics Data System (ADS)

    Svenkeson, A.; Beig, M. T.; Turalska, M.; West, B. J.; Grigolini, P.

    2013-11-01

    The fundamental connection between fractional calculus and subordination processes is explored and affords a physical interpretation of a fractional trajectory, that being an average over an ensemble of stochastic trajectories. Heretofore what has been interpreted as intrinsic friction, a form of non-Markovian dissipation that automatically arises from adopting the fractional calculus, is shown to be a manifestation of decorrelations between trajectories. We apply the general theory developed herein to the Lotka-Volterra ecological model, providing new insight into the final equilibrium state. The relaxation time to achieve this state is also considered.

  13. Agent planning in AgScala

    NASA Astrophysics Data System (ADS)

    Tošić, Saša; Mitrović, Dejan; Ivanović, Mirjana

    2013-10-01

    Agent-oriented programming languages are designed to simplify the development of software agents, especially those that exhibit complex, intelligent behavior. This paper presents recent improvements of AgScala, an agent-oriented programming language based on Scala. AgScala includes declarative constructs for managing beliefs, actions and goals of intelligent agents. Combined with object-oriented and functional programming paradigms offered by Scala, it aims to be an efficient framework for developing both purely reactive, and more complex, deliberate agents. Instead of the Prolog back-end used initially, the new version of AgScala relies on Agent Planning Package, a more advanced system for automated planning and reasoning.

  14. A FLYING WIRE SYSTEM IN THE AGS.

    SciTech Connect

    HUANG,H.; BUXTON,W.; MAHLER,G.; MARUSIC,A.; ROSER,T.; SMITH,G.; SYPHERS,M.; WILLIAMS,N.; WITKOVER,R.

    1999-03-29

    As the AGS prepares to serve as the injector for RHIC, monitoring and control of the beam transverse emittance become a major and important topic. Before the installation of the flying wire system, the emittance was measured with ionization profile monitors in the AGS, which require correction for space charge effects. It is desirable to have a second means of measuring profile that is less depend on intensity. A flying wire system has been installed in the AGS recently to perform this task. This paper discusses the hardware and software setup and the capabilities of the system.

  15. Crystallization kinetics of {alpha}-AgI in AgI-based silver orthoborate glasses

    SciTech Connect

    Taniguchi, Akihiro; Tatsumisago, Masahiro; Minami, Tsutomu

    1995-02-01

    Kinetics for nucleation and growth of {alpha}-AgI crystals in AgI-based silver orthoborate glasses, in which only {alpha}-AgI crystals were found to crystallize in the heating process of the glasses, were studied by isothermal and nonisothermal measurements using differential scanning calorimetry and by observations of the microstructure of the glasses using scanning electron microscopy. The values of both n and m, dependent on the crystallization mechanism, were found to be 3, indicating that a constant number of nuclei of {alpha}-AgI precipitated in a glass matrix grew three-dimensionally. The preannealing of the glasses at temperatures between glass transition and crystallization did not affect the DSC isothermal curves in the crystal growth process, which suggested that the number of {alpha}-AgI nuclei would have been saturated in the glass when the glasses were prepared by quenching the AgI-based melts.

  16. Extranuclear dynamics of 111Ag(→111Cd) doped in AgI nanoparticles

    NASA Astrophysics Data System (ADS)

    Sato, W.; Mizuuchi, R.; Irioka, N.; Komatsuda, S.; Kawata, S.; Taoka, A.; Ohkubo, Y.

    2014-08-01

    Dynamic behavior of the extranuclear field relative to the 111Ag(→111Cd) probe nucleus introduced in a superionic conductor silver iodide (AgI) was investigated by means of the time-differential perturbed angular correlation technique. For poly-N-vinyl-2-pyrrolidone (PVP)-coated AgI nanoparticles, we observed nuclear spin relaxation of the probe at room temperature. This result signifies that Ag+ ions in the polymer-coated sample make hopping motion from site to site at this low temperature. The activation energy for the dynamic motion was successfully estimated to be 46(10) meV. The first atomic-level observation of the temperature-dependent dynamic behavior of Ag+ ions in the polymer-coated AgI is reported.

  17. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    NASA Astrophysics Data System (ADS)

    Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

    2015-09-01

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  18. Australia's Next Top Fraction Model

    ERIC Educational Resources Information Center

    Gould, Peter

    2013-01-01

    Peter Gould suggests Australia's next top fraction model should be a linear model rather than an area model. He provides a convincing argument and gives examples of ways to introduce a linear model in primary classrooms.

  19. Ejection Fraction Heart Failure Measurement

    MedlinePlus

    ... 70. You can have a normal ejection fraction reading and still have heart failure (called HFpEF or ... to be made. Here we delve into the importance of shared decision making. HF Resources For Life ...

  20. Commercial SNF Accident Release Fractions

    SciTech Connect

    J. Schulz

    2004-11-05

    The purpose of this analysis is to specify and document the total and respirable fractions for radioactive materials that could be potentially released from an accident at the repository involving commercial spent nuclear fuel (SNF) in a dry environment. The total and respirable release fractions are used to support the preclosure licensing basis for the repository. The total release fraction is defined as the fraction of total commercial SNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. Radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses; this subset of the total release fraction is referred to as the respirable release fraction. Accidents may involve waste forms characterized as: (1) bare unconfined intact fuel assemblies, (2) confined intact fuel assemblies, or (3) canistered failed commercial SNF. Confined intact commercial SNF assemblies at the repository are contained in shipping casks, canisters, or waste packages. Four categories of failed commercial SNF are identified: (1) mechanically and cladding-penetration damaged commercial SNF, (2) consolidated/reconstituted assemblies, (3) fuel rods, pieces, and debris, and (4) nonfuel components. It is assumed that failed commercial SNF is placed into waste packages with a mesh screen at each end (CRWMS M&O 1999). In contrast to bare unconfined fuel assemblies, the

  1. Change in Seroma Volume During Whole-Breast Radiation Therapy

    SciTech Connect

    Sharma, Rajiv; Spierer, Marnee Mutyala, Subhakar; Thawani, Nitika; Cohen, Hillel W.; Hong, Linda; Garg, Madhur K.; Kalnicki, Shalom

    2009-09-01

    Purpose: After breast-conserving surgery, a seroma often forms in the surgical cavity. If not drained, it may affect the volume of tumor bed requiring a boost after whole-breast radiation therapy (WBRT). Our objective was to evaluate the change in seroma volume that occurs during WBRT, before boost planning. Methods and Materials: A retrospective review was performed of women receiving breast-conserving therapy with evidence of seroma at the time of WBRT planning. Computed tomography (CT) simulation was performed before WBRT and before the tumor bed boost. All patients received either a hypofractionated (42.4 Gy/16 fraction + 9.6 Gy/4 fraction boost) or standard fractionated (50.4 Gy/28 fraction + 10 Gy/5 fraction boost) regimen. Seroma volumes were contoured and compared on CT at the time of WBRT simulation and tumor bed boost planning. Results: Twenty-four patients with evidence of seroma were identified and all patients received WBRT without drainage of the seroma. Mean seroma volume before WBRT and at boost planning were significantly different at 65.7 cm{sup 3} (SD, 50.5 cm{sup 3}) and 35.6 cm{sup 3} (SD, 24.8 cm{sup 3}), respectively (p < 0.001). Mean and median reduction in seroma volume during radiation were 39.6% (SD, 23.8%) and 46.2% (range, 10.7-76.7%), respectively. Fractionation schedule was not correlated with change in seroma volume. Length of time from surgery to start of radiation therapy showed an inverse correlation with change in seroma volume (Pearson correlation r = -0.53, p < 0.01). Conclusions: The volume of seroma changes significantly during WBRT. Consequently, the accuracy of breast boost planning is likely affected, as is the volume of normal breast tissue irradiated. CT-based boost planning before boost irradiation is suggested to ensure appropriate coverage.

  2. Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

    SciTech Connect

    Reece, R.K.; Casella, R.; Culwick, B.; Geller, J.; Marneris, I.; Sandberg, J.; Soukas, A.; Zhang, S.Y.

    1993-01-01

    Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

  3. Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

    SciTech Connect

    Reece, R.K.; Casella, R.; Culwick, B.; Geller, J.; Marneris, I.; Sandberg, J.; Soukas, A.; Zhang, S.Y.

    1993-06-01

    Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

  4. Xenon fractionation in porous planetesimals

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin; Pollack, James B.; Kasting, James F.

    1990-01-01

    The distinctively fractionated Xe on Mars and earth may have its root in a common source from which both planets accreted. Beginning with Ozima and Nakazawa's (1980) hypothesis that terrestrial Xe fractionation was caused by gravitational separation of adsorbed solar nebular gases inside large porous planetesimals, it is pointed out that Xe would have been trapped as the planetesimal grew and pores were squeezed shut by lithostatic pressure. It is shown that enough fractionated Xe to supply the earth could have been trapped this way. The degree of fractionation is controlled by the lithostatic pressure at the pore-closing front and so would have been roughly the same for all large planetesimals. The predicted degree of fractionation agrees well with that preserved in terrestrial and Martian Xe. Relative to Xe, this source is strongly depleted in other noble gases. In contrast to the original Ozima and Nakazawa hypothesis, the present hypothesis predicts the observed fractionation, and it allows planetary accretion to occur after the dissipation of the solar nebula.

  5. Xenon fractionation in porous planetesimals.

    PubMed

    Zahnle, K; Pollack, J B; Kasting, J F

    1990-01-01

    The distinctively fractionated Xe on Mars and Earth may have its root in a common source from which both planets accreted. We begin with Ozima and Nakazawa's hypothesis that terrestrial Xe fractionation was caused by gravitational separation of adsorbed solar nebular gases inside large porous planetesimals. We point out that Xe would have been trapped as the planetesimal grew and pores were squeezed shut by lithostatic pressure. We show that enough fractionated Xe to supply the Earth could have been trapped this way. The degree of fractionation is controlled by the lithostatic pressure at the pore-closing front and so would have been roughly the same for all large planetesimals. The predicted degree of fractionation agrees well with that preserved in terrestrial and martian Xe. Relative to Xe, this source is strongly depleted in other noble gases. In contrast to the original Ozima and Nakazawa hypothesis, our hypothesis predicts the observed fractionation, and it allows planetary accretion to occur after the dissipation of the solar nebula. The required planetesimals are large, representing a class of object now extinct in the solar system.

  6. Xenon fractionation in porous planetesimals.

    PubMed

    Zahnle, K; Pollack, J B; Kasting, J F

    1990-01-01

    The distinctively fractionated Xe on Mars and Earth may have its root in a common source from which both planets accreted. We begin with Ozima and Nakazawa's hypothesis that terrestrial Xe fractionation was caused by gravitational separation of adsorbed solar nebular gases inside large porous planetesimals. We point out that Xe would have been trapped as the planetesimal grew and pores were squeezed shut by lithostatic pressure. We show that enough fractionated Xe to supply the Earth could have been trapped this way. The degree of fractionation is controlled by the lithostatic pressure at the pore-closing front and so would have been roughly the same for all large planetesimals. The predicted degree of fractionation agrees well with that preserved in terrestrial and martian Xe. Relative to Xe, this source is strongly depleted in other noble gases. In contrast to the original Ozima and Nakazawa hypothesis, our hypothesis predicts the observed fractionation, and it allows planetary accretion to occur after the dissipation of the solar nebula. The required planetesimals are large, representing a class of object now extinct in the solar system. PMID:11537194

  7. Evolution of the symbiotic binary system AG Dranconis

    NASA Technical Reports Server (NTRS)

    Mikolajewska, Joanna; Kenyon, Scott J; Mikolajewski, Maciej; Garcia, Michael R.; Polidan, Ronald S.

    1995-01-01

    We present an analysis of new and archival photometric and spectroscopic observations of the symbiotic star AG Draconis. This binary has undergone several 1 - 3 mag optical and ultraviolet eruptions during the past 15 years. Our combination of optical and ultraviolet spectroscopic data allow a more complete analysis of this system than in previous papers. AG Dra is composed of a K-type bright giant M(sub g) approximately 1.5 solar mass) and a hot, compact star M(sub h approximatelly 0.4 - 0.6 solar mass) embedded in a dense, low metallicity nebula. The hot component undergoes occasional thermonuclear runaways that produce 2 - 3 mag optical/ultraviolet eruptions. During these eruptions, the hot component develops a low velocity wind that quenches x-ray emission from the underlying hot white dwarf. The photoionized nebula changes its volume by a factor of 5 throughout an eruptin cycle. The K bright giant occults low ionization emission lines during superior conjunctions at all outburst phases but does not occult high ionization lines in outburst (and perhaps quiescence). This geometry and the component masses suggest a system inclination of i approximately 30 deg - 45 deg.

  8. Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

    2011-07-01

    Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

  9. Near-infrared emitting AgInTe2 and Zn-Ag-In-Te colloidal nanocrystals

    NASA Astrophysics Data System (ADS)

    Langevin, Marc-Antoine; Pons, Thomas; Ritcey, Anna M.; Nì. Allen, Claudine

    2015-06-01

    The synthesis of AgInTe2 nanocrystals emitting between 1095 nm and 1160 nm is presented. Evolution of the Ag:In:Te ratio shows progressive incorporation of In3+ in Ag2Te, leading to the formation of orthorhombic AgInTe2. When zinc is added to the synthesis, the photoluminescence quantum yield reaches 3.4 %.

  10. Redetermination of AgPO3

    PubMed Central

    Terebilenko, Katherina V.; Zatovsky, Igor V.; Ogorodnyk, Ivan V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.

    2011-01-01

    Single crystals of silver(I) polyphosphate(V), AgPO3, were prepared via a phospho­ric acid melt method using a solution of Ag3PO4 in H3PO4. In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779–784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO5] polyhedra, giving rise to multidirectional ribbons, and from two types of PO4 tetra­hedra linked into meandering chains (PO3)n spreading parallel to the b axis with a repeat unit of four tetra­hedra. The calculated bond-valence sum value of one of the two AgI ions indicates a significant strain of the structure. PMID:21522230

  11. Redetermination of AgPO(3).

    PubMed

    Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

    2011-02-09

    Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure.

  12. Redetermination of AgPO(3).

    PubMed

    Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

    2011-01-01

    Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure. PMID:21522230

  13. Role of surface states in Auger neutralization of He{sup +} ions on Ag surfaces

    SciTech Connect

    Sarasola, A.; Silkin, V. M.; Arnau, A.

    2007-01-15

    Recent measurements of He{sup +} ion fractions that survive to a whole scatterig event when they impinge on Ag surfaces have shown two different and interesting effects: (1) a notable difference of surviving ion fraction depending on which crystallographic face of the target surface is studied [Yu. Bandurin et al., Phys. Rev. Lett. 92, 017601 (2004)], and (2) an uncommonly high ion fraction in the very-low-energy range (tens of eV) [S. Wethekam et al., Phys. Rev. Lett. 90, 037602 (2003)]. Apart from the geometry, one of the differences between the surfaces of a crystal can be seen in the electronic structure: while the (111) surface has an occupied surface state near the Fermi level at the {gamma} point the (110) and (100) faces have not. Motivated by these facts, in this work we study the role that the occupied surface state plays on the Auger neutralization rate and we present an estimation of the ion fractions that survive for the different Ag faces.

  14. Fractional characteristic times and dissipated energy in fractional linear viscoelasticity

    NASA Astrophysics Data System (ADS)

    Colinas-Armijo, Natalia; Di Paola, Mario; Pinnola, Francesco P.

    2016-08-01

    In fractional viscoelasticity the stress-strain relation is a differential equation with non-integer operators (derivative or integral). Such constitutive law is able to describe the mechanical behavior of several materials, but when fractional operators appear, the elastic and the viscous contribution are inseparable and the characteristic times (relaxation and retardation time) cannot be defined. This paper aims to provide an approach to separate the elastic and the viscous phase in the fractional stress-strain relation with the aid of an equivalent classical model (Kelvin-Voigt or Maxwell). For such equivalent model the parameters are selected by an optimization procedure. Once the parameters of the equivalent model are defined, characteristic times of fractional viscoelasticity are readily defined as ratio between viscosity and stiffness. In the numerical applications, three kinds of different excitations are considered, that is, harmonic, periodic, and pseudo-stochastic. It is shown that, for any periodic excitation, the equivalent models have some important features: (i) the dissipated energy per cycle at steady-state coincides with the Staverman-Schwarzl formulation of the fractional model, (ii) the elastic and the viscous coefficients of the equivalent model are strictly related to the storage and the loss modulus, respectively.

  15. Isotope fractionation studies of molybdenum

    NASA Astrophysics Data System (ADS)

    Wieser, M. E.; de Laeter, J. R.; Varner, M. D.

    2007-08-01

    Mass spectrometric studies of the isotopic composition of molybdenum have become an active area of research in stable isotope geochemistry, biogeochemistry and cosmochemistry. The redox chemistry of Mo, together with its proclivity for covalent bonding, indicates its importance in isotope fractionation studies such as palaeoceanography. The measurement of the magnitude of isotope fractionation of Mo in natural systems is a challenging task, in that natural fractionation has to be carefully distinguished from chemical and instrumental isotope fractionation. An ion exchange chemical separation procedure has been developed with high efficiency and low blank, to ensure that the isobaric elements Zr and Ru are removed from the samples before mass spectrometric analysis. The isotope fractionation resulting from this procedure is 0.14[per mille sign] per u. The isotopic composition of Mo of a Laboratory Standard has been measured by positive and negative thermal ionization mass spectrometry (P-TIMS and N-TIMS, respectively), to give an isotope fractionation of 6.4[per mille sign] and 0.5[per mille sign] per u, respectively, with respect to the absolute isotope abundances of Mo. In both cases the lighter isotopes are enhanced with respect to the heavier isotopes. An ascorbic acid activator has enabled the sensitivity of P-TIMS to be improved as compared to traditional methods. The same experiment was repeated using a multiple collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS) to give an isotope fractionation of approximately 17.0[per mille sign] per u. In this case the heavier isotopes are enhanced with respect to the lighter isotopes. The strengths and weaknesses of these three mass spectrometric techniques are evaluated. We conclude that MC-ICP-MS is the optimum mass spectrometric method for accurately measuring the isotope fractionation of Mo in natural materials, provided chemical and instrumental isotope fractionation can be resolved from naturally

  16. AgRISTARS documents tracking list report

    NASA Technical Reports Server (NTRS)

    Hawkins, J. L.

    1982-01-01

    A quarterly listing of those documents and related publications that have been issued and placed in the AgRISTARS tracking system is presented. The Tracking List Report provides a catalog, by project, of technical publications arranged by type of document and gives the reference AgRISTARS document numbers, title and date of publication, the issuing organization, and the National Technical Information Service reference number.

  17. 20% PARTIAL SIBERIAN SNAKE IN THE AGS.

    SciTech Connect

    Huang, H; Bai, M; Brown, K A; Glenn, W; Luccio, A U; Mackay, W W; Montag, C; Ptitsyn, V; Roser, T; Tsoupas, N; Zeno, K; Ranjbar, V; Spinka, H; Underwood, D

    2002-11-06

    An 11.4% partial Siberian snake was used to successfully accelerate polarized proton through a strong intrinsic depolarizing spin resonance in the AGS. No noticeable depolarization was observed. This opens up the possibility of using a 20% to 30% partial Siberian snake in the AGS to overcome all weak and strong depolarizing spin resonances. Some design and operation issues of the new partial Siberian snake are discussed.

  18. Catalytic Properties of AgPt Nanoshells as a Function of Size: Larger Outer Diameters Lead to Improved Performances.

    PubMed

    Rodrigues, Thenner S; da Silva, Anderson G M; Gonçalves, Mariana C; Fajardo, Humberto V; Balzer, Rosana; Probst, Luiz F D; da Silva, Alisson H M; Assaf, Jose M; Camargo, Pedro H C

    2016-09-13

    We report herein a systematic investigation on the effect of the size of silver (Ag) nanoparticles employed as starting materials over the morphological features and catalytic performances of AgPt nanoshells produced by a combination of galvanic replacement between Ag and PtCl6(2-) and PtCl6(2-) reduction by hydroquinone. More specifically, we focused on Ag nanoparticles of four different sizes as starting materials, and found that the outer diameter, shell thickness, and the number of Pt surface atoms of the produced nanoshells increased with the size of the starting Ag nanoparticles. The produced AgPt nanoshells were supported into SiO2, and the catalytic performances of the AgPt/SiO2 nanocatalysts toward the gas-phase oxidation of benzene, toluene, and o-xylene (BTX oxidation) followed the order: AgPt 163 nm/SiO2 > AgPt 133 nm/SiO2 > AgPt 105 nm/SiO2 > AgPt 95 nm/SiO2. Interestingly, bigger AgPt nanoshell sizes lead to better catalytic performances in contrast to the intuitive prediction that particles having larger outer diameters tend to present poorer catalytic activities due to their lower surface to volume ratios as compared to smaller particles. This is in agreement with the H2 chemisorption results, and can be assigned to the increase in the Pt surface area with size due to the presence of smaller NPs islands at the surface of the nanoshells having larger outer diameters. This result indicates that, in addition to the overall diameters, the optimization of the surface morphology may play an important role over the optimization of catalytic activities in metal-based nanocatalysts, which can be even more pronounced that the size effect. Our data demonstrate that the control over surface morphology play a very important role relative to the effect of size to the optimization of catalytic performances in catalysts based on noble-metal nanostructures. PMID:27556904

  19. Acceleration of polarized protons in the AGS

    SciTech Connect

    Tsoupas, N.; Ahrens, L.; Bai, M.; Brown, K.; Courant, E.; Glenn, J.W.; Huang, H.; Luccio, A.; MacKay, W.W.; Roser, T.; Schoefer, V.; Zeno, K.

    2010-02-25

    The high energy (s{sup 1/2} = 500 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the proton beam. With the AGS used as the pre-injector to RHIC, one of the main tasks is to preserve the polarization of the proton beam, during the beam acceleration in the AGS. The polarization preservation is accomplished by the two partial helical magnets [1,2,3,4,5,6,7] which have been installed in AGS, and help overcome the imperfection and the intrinsic spin resonances which occur during the acceleration of protons. This elimination of the intrinsic resonances is accomplished by placing the vertical tune Q{sub y} at a value close to 8.98, within the spin-tune stop-band created by the snake. At this near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads[2] in the AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices.

  20. A visible-light-driven core-shell like Ag2S@Ag2CO3 composite photocatalyst with high performance in pollutants degradation.

    PubMed

    Yu, Changlin; Wei, Longfu; Zhou, Wanqin; Dionysiou, Dionysios D; Zhu, Lihua; Shu, Qing; Liu, Hong

    2016-08-01

    A series of Ag2S-Ag2CO3 (4%, 8%, 16%, 32% and 40% Ag2S), Ag2CO3@Ag2S (32%Ag2S) and Ag2S@Ag2CO3 (32%Ag2S) composite photocatalysts were fabricated by coprecipitation or successive precipitation reaction. The obtained catalysts were analyzed by N2 physical adsorption, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and photocurrent test. Under visible light irradiation, the influences of Ag2S content and core-shell property on photocatalytic activity and stability were evaluated in studies focused on the degradation of methyl orange (MO) dye, phenol, and bisphenol A. Results showed that excellent photocatalytic performance was obtained over Ag2S/Ag2CO3 composite photocatalysts with respect to Ag2S and Ag2CO3. With optimal content of Ag2S (32 wt%), the Ag2S-Ag2CO3 showed the highest photocatalytic degradation efficiency. Moreover, the structured property of Ag2S/Ag2CO3 greatly influenced the activity. Compared with Ag2S-Ag2CO3 and Ag2CO3@Ag2S, core-shell like Ag2S@Ag2CO3 demonstrated the highest activity and stability. The main reason for the boosting of photocatalytic performance was due to the formation of Ag2S/Ag2CO3 well contacted interface and unique electron structures. Ag2S/Ag2CO3 interface could significantly increase the separation efficiency of the photo-generated electrons (e(-)) and holes (h(+)), and production of OH radicals. More importantly, the low solubility of Ag2S shell could effectively protect the core of Ag2CO3, which further guarantees the stability of Ag2CO3. PMID:27236845

  1. Final Report for Fractionation and Separation of Polydisperse Nanoparticles into Distinct Monodisperse Fractions Using CO2 Expanded Liquids

    SciTech Connect

    Chistopher Roberts

    2007-08-31

    The overall objective of this project was to facilitate efficient fractionation and separation of polydisperse metal nanoparticle populations into distinct monodisperse fractions using the tunable solvent properties of gas expanded liquids. Specifically, the dispersibility of ligand-stabilized nanoparticles in an organic solution was controlled by altering the ligand-solvent interaction (solvation) by the addition of carbon dioxide (CO{sub 2}) gas as an antisolvent (thereby tailoring the bulk solvent strength) in a custom high pressure apparatus developed in our lab. This was accomplished by adjusting the CO{sub 2} pressure over the liquid dispersion, resulting in a simple means of tuning the nanoparticle precipitation by size. Overall, this work utilized the highly tunable solvent properties of organic/CO{sub 2} solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (ranging from 1 to 20 nm in size) into monodisperse fractions ({+-}1nm). Specifically, three primary tasks were performed to meet the overall objective. Task 1 involved the investigation of the effects of various operating parameters (such as temperature, pressure, ligand length and ligand type) on the efficiency of separation and fractionation of Ag nanoparticles. In addition, a thermodynamic interaction energy model was developed to predict the dispersibility of different sized nanoparticles in the gas expanded liquids at various conditions. Task 2 involved the extension of the experimental procedures identified in task 1 to the separation of other metal particles used in catalysis such as Au as well as other materials such as semiconductor particles (e.g. CdSe). Task 3 involved using the optimal conditions identified in tasks 1 and 2 to scale up the process to handle sample sizes of greater than 1 g. An experimental system was designed to allow nanoparticles of increasingly smaller sizes to be precipitated sequentially in a vertical series of high pressure vessels by

  2. Fractional Brownian motion, fractional Gaussian noise, and Tsallis permutation entropy

    NASA Astrophysics Data System (ADS)

    Zunino, L.; Pérez, D. G.; Kowalski, A.; Martín, M. T.; Garavaglia, M.; Plastino, A.; Rosso, O. A.

    2008-10-01

    In this work, we analyze two important stochastic processes, the fractional Brownian motion and fractional Gaussian noise, within the framework of the Tsallis permutation entropy. This entropic measure, evaluated after using the Bandt & Pompe method to extract the associated probability distribution, is shown to be a powerful tool to characterize fractal stochastic processes. It allows for a better discrimination of the processes than the Shannon counterpart for appropriate ranges of values of the entropic index. Moreover, we find the optimum value of this entropic index for the stochastic processes under study.

  3. Radiation Dose-Volume Effects in the Spinal Cord

    SciTech Connect

    Kirkpatrick, John P.; Kogel, Albert J. van der; Schultheiss, Timothy E.

    2010-03-01

    Dose-volume data for myelopathy in humans treated with radiotherapy (RT) to the spine is reviewed, along with pertinent preclinical data. Using conventional fractionation of 1.8-2 Gy/fraction to the full-thickness cord, the estimated risk of myelopathy is <1% and <10% at 54 Gy and 61 Gy, respectively, with a calculated strong dependence on dose/fraction (alpha/beta = 0.87 Gy.) Reirradiation data in animals and humans suggest partial repair of RT-induced subclinical damage becoming evident about 6 months post-RT and increasing over the next 2 years. Reports of myelopathy from stereotactic radiosurgery to spinal lesions appear rare (<1%) when the maximum spinal cord dose is limited to the equivalent of 13 Gy in a single fraction or 20 Gy in three fractions. However, long-term data are insufficient to calculate a dose-volume relationship for myelopathy when the partial cord is treated with a hypofractionated regimen.

  4. Investigation of the structure of a Ag/Pd/Ag( 1 1 1 ) trilayer by means of electronic spectroscopies

    NASA Astrophysics Data System (ADS)

    Dumont, J.; Ghijsen, J.; Sporken, R.

    2002-06-01

    The growth of the Ag/Pd/Ag system has been studied by X-ray photoelectron spectroscopy and low energy electron diffraction. No chemical reaction or interdiffusion was observed between the Pd and Ag layers. The growth of the Pd interlayer follows the Frank Van der Merwe mode but is not pseudomorphic on the Ag(1 1 1) substrate. The growth of the top Ag layer on the Pd interlayer is pseudomorphic and layer by layer but contains around 12% of voids.

  5. Ag contact properties according to the front grid width and firing temperature for silicon solar cells.

    PubMed

    Kim, Seongtak; Park, Sungeun; Kim, Young Do; Bae, Soohyun; Boo, Hyunpil; Kim, Hyunho; Lee, Kyung Dong; Tark, Sung Ju; Kim, Donghwan

    2014-10-01

    The effect of peak firing temperature and grid width on the contact properties between Ag metal and silicon (n+ emitter) was investigated for screen-printed silicon solar cells. We confirmed the factors that control the specific contact resistance as follows: (1) the Ag coverage fraction on the silicon surface, d(2) the thickness of the glass layer and (3) the etching depth on the n+ emitter region. The lowest specific contact resistance (8.27 mΩ x cm2) was obtained at the optimum firing temperature (720 degrees C). We also found that the grid width affected the contact quality of Ag paste because the contact width related to the absorbed heat of samples in RTP system. For this reason, when the grid width was further reduced, meaning more heat absorption, more Ag crystallites grew and the glass layer thickened. Light I-V results of a 6-inch silicon solar cell with minimum busbar width were similar to the PC1D simulation results. The efficiency was improved by 0.2% with the reduction of the busbar width.

  6. Delayed coker fractionator advanced control

    SciTech Connect

    Jaisinghani, R.; Minter, B. ); Tica, A.; Puglesi, A.; Ojeda, R. )

    1993-08-01

    In a delayed coking process, as coke drum switches are made, rapid changes occur in both the fractionator feed rate and composition. With conventional control, it is not unusual to see long transient behavior of large swings in both quality and flowrates of coker gas oils. This can extract a heavy economic toll, not only in coker operation, but in the operation of downstream units as the upset is propagated. An advanced process control application (APC) was recently implemented on the coker fractionator at the Yacimentos Petroliferos Fiscales (YPF), Lujan de Cuyo Refinery, in Mendoza, Argentina. This coker fractionator control design was unique as it handled two different operating objectives: control of product qualities via tower temperature profile during normal operation and control of gas oil product flow ratio during drum switch. This combination of control objectives in one multivariable predictive control program was achieved by including special logic to decouple the individual tuning requirements. Also, additional logic was included to unambiguously detect and identify drum switch and drum steam out as discrete events within 30 seconds of their actual occurrence. These discrete events were then used as disturbance variables to minimize fractionator transient behavior. As a performance measure, the overhead temperature was controlled within 2 C to 2.5 C of its target, gas oil flows were stabilized during drum switches and steam generation via pump around was maximized. Overall, implementing advanced control for the delayed coker fractionator resulted in substantial benefits from product quality control, product flow control and minimized energy consumption.

  7. Search for fractionally charged particles

    SciTech Connect

    Lackner, K.S.; Zweig, G.

    1982-01-01

    Quarks, the constituents of hadrons and fermion fields of quantum chromodynamics, have fractional charges -1/3e and 2/3e. All charges are integral multiples of 1/3e and not e, as was previously believed. Therefore it is natural to ask if isolated particles of fractional charge exist, either as an intrinsic part of matter, or as particles that can be produced at high energy accelerators. This question can only be answered by experiment, and remains interesting even if quantum chromodynamics turns out to be an absolutely confining theory of quarks. For example, small deviations from the standard version of quantum chromodynamics, or the incorporation of quantum chromodynamics into a more comprehensive theory, could require the existence of free fractionally charged particles.

  8. Diffusion across the modified polyethylene separator GX in the heat-sterilizable AgO-Zn battery

    NASA Technical Reports Server (NTRS)

    Lutwack, R.

    1973-01-01

    Models of diffusion across an inert membrane have been studied using the computer program CINDA. The models were constructed to simulate various conditions obtained in the consideration of the diffusion of Ag (OH)2 ions in the AgO-Zn battery. The effects on concentrations across the membrane at the steady state and on the fluxout as a function of time were used to examine the consequences of stepwise reducing the number of sources of ions, of stepwise blocking the source and sink surfaces, of varying the magnitude of the diffusion coefficient for a uniform membrane, of varying the diffusion coefficient across the membrane, and of excluding volumes to diffusion.

  9. REFractions: The Representing Equivalent Fractions Game

    ERIC Educational Resources Information Center

    Tucker, Stephen I.

    2014-01-01

    Stephen Tucker presents a fractions game that addresses a range of fraction concepts including equivalence and computation. The REFractions game also improves students' fluency with representing, comparing and adding fractions.

  10. Facile synthesis of sunlight-driven AgCI:Ag plasmonic nanophotocatalyst.

    SciTech Connect

    An, C.; Peng, S.; Sun, Y.; Center for Nanoscale Materials; Univ. of Illinois

    2010-06-18

    Highly efficient plasmonic photocatalysts of AgCl:Ag hybrid nanoparticles are successfully synthesized via a one-pot synthetic approach involving a precipitation reaction followed by polyol reduction. The as-synthesized nanoparticles exhibit high catalytic performance under visible light and sunlight for decomposing organics, such as methylene blue.

  11. Beet Juice-Induced Green Fabrication of Plasmonic AgCl/Ag Nanoparticles

    EPA Science Inventory

    A simple, green, and fast approach (complete within 5 min) was explored for the fabrication of hybrid AgCl/Ag plasmonic nanoparticles under microwave (MW) irradiation. In this method, beet juice served as a reducing reagent, which is an abundant sugar-rich agricultural produce. I...

  12. Ultra-Fast Synthesis for Ag2Se and CuAgSe Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    DUAN, H. Z.; LI, Y. L.; ZHAO, K. P.; QIU, P. F.; SHI, X.; CHEN, L. D.

    2016-10-01

    Ag2Se and CuAgSe have been recently reported as promising thermoelectric materials at room temperature. The traditional melting-annealing-sintering processes are used to grow Ag2Se and CuAgSe materials with the disadvantages of high costs of energy and time. In this work, phase-pure polycrystalline Ag2Se and CuAgSe compounds were synthesized from raw elemental powders directly by manual mixing followed by spark plasma sintering (MM-SPS) in a few minutes. The influence of SPS heating rate on the phase composition, microstructure, and thermoelectric properties, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were investigated. The zTs of 0.8 at 390 K and 0.6 at 450 K are obtained for Ag2Se and CuAgSe, respectively, which is comparable with the values in the materials prepared by the traditional method. Furthermore, this ultrafast sample synthesis can significantly save material synthesis time and thus has the obvious advantage for large-scale production.

  13. EXAFS Studies of Bimetallic Ag-Pt and Ag-Pd Nanorods

    SciTech Connect

    Lahiri, D.; Chattopadhyay, S.; Bunker, B.A.; Doudna, C.M.; Bertino, M.F.; Blum, F.; Tokuhiro, A.; Terry, J.

    2008-10-30

    Nanoparticles of Ag-Pt and Ag-Pd with high aspect ratios were synthesized using a radiolysis method. Gamma rays at dose rates below 0.5 kGy/h were used for irradiation. The nanoparticles were characterized by transmission electron microscopy (TEM), optical absorption spectroscopy and x-ray Absorption Fine Structure (XAFS) spectroscopy. Bright field micrographs show that Ag-Pt nanowires are composed of large particles with diameters ranging from 20-30 nm and joined by filaments of diameter between 2-5 nm. The Ag-Pd nanowires have diameters of 20-25 nm and lengths of 1.5 {micro}m. For XAFS measurements, the Pt L3 edge (11.564 keV), Ag K-edge (25.514 keV) and Pd K-edge (24.350 keV) were excited to determine the local structure around the respective atoms in the cluster. The Ag-Pt particles were found to possess a distinct core-shell structure with Pt in the core surrounded by Ag shell, with no indication of alloy formation. However, nanorods of Ag-Pd have formed an alloy for all the alloy compositions.

  14. Ultra-Fast Synthesis for Ag2Se and CuAgSe Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    DUAN, H. Z.; LI, Y. L.; ZHAO, K. P.; QIU, P. F.; SHI, X.; CHEN, L. D.

    2016-06-01

    Ag2Se and CuAgSe have been recently reported as promising thermoelectric materials at room temperature. The traditional melting-annealing-sintering processes are used to grow Ag2Se and CuAgSe materials with the disadvantages of high costs of energy and time. In this work, phase-pure polycrystalline Ag2Se and CuAgSe compounds were synthesized from raw elemental powders directly by manual mixing followed by spark plasma sintering (MM-SPS) in a few minutes. The influence of SPS heating rate on the phase composition, microstructure, and thermoelectric properties, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were investigated. The zTs of 0.8 at 390 K and 0.6 at 450 K are obtained for Ag2Se and CuAgSe, respectively, which is comparable with the values in the materials prepared by the traditional method. Furthermore, this ultrafast sample synthesis can significantly save material synthesis time and thus has the obvious advantage for large-scale production.

  15. Ultra-sensitive detection of Ag+ ions based on Ag+-assisted isothermal exponential degradation reaction.

    PubMed

    Zhao, Jing; Fan, Qi; Zhu, Sha; Duan, Aiping; Yin, Yongmei; Li, Genxi

    2013-01-15

    Ag(+) ions are greatly toxic to a lot of algae, fungi, viruses and bacteria, which can also induce harmful side-effects to environments and human health. Herein we report an ultra-sensitive method for the selective detection of Ag(+) ions with electrochemical technique based on Ag(+)-assisted isothermal exponential degradation reaction. In the presence of Ag(+), mismatched trigger DNA can transiently bind to template DNA immobilized on an electrode surface through the formation of C-Ag(+)-C base pair, which then initiates the isothermal exponential degradation reaction. As a result, the mismatched trigger DNA may melt off the cleaved template DNA to trigger rounds of elongation and cutting. After the cyclic degradation reactions, removal of the template DNA immobilized on the electrode surface can be efficiently monitored by using electrochemical technique to show the status of the electrode surface, which can be then used to determine the presence of Ag(+). Further studies reveal that the proposed method can be ultra-sensitive to detect Ag(+) at a picomolar level. The selectivity of the detection can also be satisfactory, thus the proposed method for the Ag(+) ions detection may be potentially useful in the future. PMID:22921090

  16. Ag on Si(111) from basic science to application

    SciTech Connect

    Belianinov, Aleksey

    2012-01-01

    In our work we revisit Ag and Au adsorbates on Si(111)-7x7, as well as experiment with a ternary system of Pentacene, Ag and Si(111). Of particular interest to us is the Si(111)-(√3x√3)R30°}–Ag (Ag-Si-√3 hereafter). In this thesis I systematically explore effects of Ag deposition on the Ag-Si-√3 at different temperatures, film thicknesses and deposition fluxes. The generated insight of the Ag system on the Si(111) is then applied to generate novel methods of nanostructuring and nanowire growth. I then extend our expertise to the Au system on the Ag-Si(111) to gain insight into Au-Si eutectic silicide formation. Finally we explore behavior and growth modes of an organic molecule on the Ag-Si interface.

  17. Enhanced thermoelectric performance of CdO : Ag nanocomposites.

    PubMed

    Gao, Linjie; Wang, Shufang; Liu, Ran; Zha, Xinyu; Sun, Niefeng; Wang, Shujie; Wang, Jianglong; Fu, Guangsheng

    2016-07-26

    CdO : Ag nanocomposites with metallic Ag nanoparticles embedded in the polycrystalline CdO matrix were synthesized by the solid-state reaction method. The addition of Ag led to increased grain boundaries of CdO and created numerous CdO/Ag interfaces. By incorporating Ag into the CdO matrix, the power factor was increased which was probably due to the carrier energy filtering effect induced by the enhanced energy-dependent scattering of electrons. In addition, reduced thermal conductivity was also achieved by stronger phonon scattering from grain boundaries, CdO/Ag interfaces and Ag nanoparticles. These concomitant effects resulted in enhanced ZT values for all CdO : Ag nanocomposites, demonstrating that the strategy of introducing metallic Ag nanoparticles into the CdO host was very effective in optimizing the thermoelectric performance. PMID:27411573

  18. Fractional Derivatives in Dengue Epidemics

    NASA Astrophysics Data System (ADS)

    Pooseh, Shakoor; Rodrigues, Helena Sofia; Torres, Delfim F. M.

    2011-09-01

    We introduce the use of fractional calculus, i.e., the use of integrals and derivatives of non-integer (arbitrary) order, in epidemiology. The proposed approach is illustrated with an outbreak of dengue disease, which is motivated by the first dengue epidemic ever recorded in the Cape Verde islands off the coast of west Africa, in 2009. Numerical simulations show that in some cases the fractional models fit better the reality when compared with the standard differential models. The classical results are obtained as particular cases by considering the order of the derivatives to take an integer value.

  19. On fractional Model Reference Adaptive Control.

    PubMed

    Shi, Bao; Yuan, Jian; Dong, Chao

    2014-01-01

    This paper extends the conventional Model Reference Adaptive Control systems to fractional ones based on the theory of fractional calculus. A control law and an incommensurate fractional adaptation law are designed for the fractional plant and the fractional reference model. The stability and tracking convergence are analyzed using the frequency distributed fractional integrator model and Lyapunov theory. Moreover, numerical simulations of both linear and nonlinear systems are performed to exhibit the viability and effectiveness of the proposed methodology. PMID:24574897

  20. Right ventricular volume analysis by angiography in right ventricular cardiomyopathy.

    PubMed

    Indik, Julia H; Dallas, William J; Gear, Kathleen; Tandri, Harikrishna; Bluemke, David A; Moukabary, Talal; Marcus, Frank I

    2012-06-01

    Imaging of the right ventricle (RV) for the diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is commonly performed by echocardiography or magnetic resonance imaging (MRI). Angiography is an alternative modality, particularly when MRI cannot be performed. We hypothesized that RV volume and ejection fraction computed by angiography would correlate with these quantities as computed by MRI. RV volumes and ejection fraction were computed for subjects enrolled in the North American ARVC/D Registry, with both RV angiography and MRI studies. Angiography was performed in the 30° right anterior oblique (RAO) and 60° left anterior oblique (LAO) views. Angiographic volumes were computed by RAO view and two-view (RAO and LAO) formulae. 17 subjects were analyzed (11 men and 6 women), with 15 subjects classified as affected, and two as unaffected by modified Task Force criteria. The correlation coefficient of MRI to the two-view angiographic analysis was 0.72 (P = 0.003) for end-diastolic volume and 0.68 (P = 0.005) for ejection fraction. Angiographically derived volumes were larger than MRI derived volume (P = 0.009) and with the slope in a linear relationship equal to 0.8 for end diastolic volume, and 0.9 for RV ejection fraction (P < 0.001), computed by the two view formula. End-diastolic volumes and ejection fractions of the RV obtained by dual view angiography correlate with these quantities by MRI. RV end-diastolic volumes are larger by RV angiography in comparison with MRI.