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Sample records for moessbauer effect investigation

  1. Moessbauer effect: Study of disordered magnetic systems

    SciTech Connect

    Chang, Xiao Sha.

    1989-01-01

    This dissertation describes Moessbauer spectroscopy studies of two chemically disordered binary, crystalline alloys having the composition A{sub 1-x}B{sub x}. Both systems are random 3d Heisenberg ferromagnets. In each case both A and B atoms carry a magnetic moment. The first study concerns a Moessbauer absorber experiment on Fe{sub 1-x} V{sub x}, in which the disorder in the critical region is of the annealed random exchange type. To eliminate the effect of concentration inhomogeneity, the measurement of the critical exponent {beta} was done on the alloy with x = 0.125, where dT{sub C}/dx = 0, yielding {beta} = 0.362(8) over the reduced temperature range 1.4 {times} 10{sup {minus}3} < t < 4.88 {times} 10{sup {minus}1}. This result confirms the theoretical prediction that the annealed disorder is irrelevant to critical behavior in this case. As expected the critical exponent {beta} is consistent with the expectation for the 3d Heisenberg model as well as the measured exponent of pure Fe. The second study involves a Moessbauer source experiment on {sup 57} CoPd{sub 0.80}Co{sub 0.20}, in which disorder is of the quenched random exchange type perturbed by a very weak random anisotropy interaction. The critical exponent {beta} deduced over the range 1 {times} 10{sup {minus}2} < t < 2 {times} 10{sup {minus}1} is 0.385(20), and is consistent with the theoretical prediction for quenched disordered 3d Heisenberg systems: the disorder is irrelevant to the critical behavior. However, because of the restricted range of reduced temperature, the result is insufficiently asymptotic to serve as a conclusive test of the theory. Outside the critical region the distribution of Fe{sup 57} hyperfine field in Pd{sub 0.80}Co{sub 0.20} is observed to have an anomalous temperature dependence characterized by a linear increase in the width of the field distribution for T/T{sub C} {ge} 0.6.

  2. Synthesis and investigation of iron (II) dioximates with arsine derivatives by Moessbauer and IR spectroscopy

    SciTech Connect

    Zubareva, V.E.; Turte, K.I.; Shafranskii, V.N.; Bulgak, I.I.; Batyr, D.G.; Stukan, R.A.

    1988-06-01

    New compounds with the formula (Fe/sup II/(dioximate)/sub 2/L/sub 2/), where dioximate stands for monodeprotonated anions of dimethylglyoxime (dmgH), diphenylglyoxime (dfgH), 1,2-cyclohexanedione dioxime (nioxH), and ..cap alpha..-furildioxime (furgH), and L stands for di-n-butylphenylarsine (AsBut/sub 2/Ph) and triethylarsine (AsEt/sub 3/), have been investigated by Moessbauer and IR spectroscopy. The Moessbauer spectra of the compounds indicated at 80 and 300/sup 0/K consist of doublets, whose parameters correspond to the low-spin state of iron (II).

  3. Investigation of potential analytical methods for redox control of the vitrification process. [Moessbauer

    SciTech Connect

    Goldman, D.S.

    1985-11-01

    An investigation was conducted to evaluate several analytical techniques to measure ferrous/ferric ratios in simulated and radioactive nuclear waste glasses for eventual redox control of the vitrification process. Redox control will minimize the melt foaming that occurs under highly oxidizing conditions and the metal precipitation that occurs under highly reducing conditions. The analytical method selected must have a rapid response for production problems with minimal complexity and analyst involvement. The wet-chemistry, Moessbauer spectroscopy, glass color analysis, and ion chromatography techniques were explored, with particular emphasis being placed on the Moessbauer technique. In general, all of these methods can be used for nonradioactive samples. The Moessbauer method can readily analyze glasses containing uranium and thorium. A shielded container was designed and built to analyze fully radioactive glasses with the Moessbauer spectrometer in a hot cell environment. However, analyses conducted with radioactive waste glasses containing /sup 90/Sr and /sup 137/Cs were unsuccessful, presumably due to background radiation problems caused by the samples. The color of glass powder can be used to analyze the ferrous/ferric ratio for low chromium glasses, but this method may not be as precise as the others. Ion chromatography was only tested on nonradioactive glasses, but this technique appears to have the required precision due to its analysis of both Fe/sup +2/ and Fe/sup +3/ and its anticipated adaptability for radioactivity samples. This development would be similar to procedures already in use for shielded inductively coupled plasma emission (ICP) spectrometry. Development of the ion chromatography method is therefore recommended; conventional wet-chemistry is recommended as a backup procedure.

  4. Investigations of Iron Minerals Formed by Dissimilatory Alkaliphilic Bacterium with {sup 57}Fe Moessbauer Spectroscopy

    SciTech Connect

    Chistyakova, N. I.; Rusakov, V. S.; Shapkin, A. A.; Zhilina, T. N.; Zavarzina, D. G.; Kohout, J.

    2010-07-13

    Anaerobic alkaliphilic bacterium of Geoalkalibacter ferrihydriticus type (strain Z-0531), isolated from a bottom sediment sample from the weakly mineralized soda Lake Khadyn, have been analyzed. The strain uses the amorphous Fe(III)-hydroxide (AFH) as an electron acceptor and acetate CH{sub 3}COO{sup -} as an electron donor. Moessbauer investigations of solid phase samples obtained during the process of the bacterium growth were carried out at room temperature, 77.8 K, 4.2 K without and with the presence of an external magnetic field (6 T) applied perpendicular to the {gamma}-bebam.

  5. Moessbauer effect measurement in single crystal iron subjected to cyclic stress

    NASA Technical Reports Server (NTRS)

    Singh, J. J.

    1976-01-01

    Backscattered Moessbauer spectra were recorded at different fatigue levels in cyclically fatigued high-purity single-crystal iron specimens in the form of rectangular strips with appropriate concentrators in the midplane. The Moessbauer spectra were submitted to a least-squares analysis to determine the isomer shift, quadrupole shift, hyperfine field, and peak spectral widths in each spectrum. It is shown that the quadrupole shift and the isomer shift changed little with fatigue, whereas the effective internal field and the associate line widths exhibit significant variation as a function of fatigue level. It is concluded that the impurity concentration builds up slowly with increasing fatigue level in the region of stress concentration. Since there is a direct correlation between crack initiation and defect concentration level, it is expected that Moessbauer measurements in the test specimen can provide a means of monitoring the impurity buildup presumed to be the eventual cause of fatigue crack initiation and failure.

  6. Moessbauer Nose Print

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image was taken by the microscopic imager, an instrument located on the Mars Exploration Rover Opportunity 's instrument deployment device, or 'arm.' The image shows the imprint of the donut-shaped plate on the rover's Moessbauer spectrometer instrument, also located on the 'arm.' The Moessbauer spectrometer was deployed within the trench to investigate the fine-grained soil for iron-bearing minerals. The area in this image measures approximately 3 centimeters (1.2 inches) across.

  7. Effect of nanocrystallization on the electrical conductivity enhancement and Moessbauer hyperfine parameters of iron based glasses

    SciTech Connect

    El-Desoky, M.M.; Ibrahim, F.A.; Mostafa, A.G.; Hassaan, M.Y.

    2010-09-15

    Selected glasses of Fe{sub 2}O{sub 3}-PbO{sub 2}-Bi{sub 2}O{sub 3} system have been transformed into nanomaterials by annealing at temperature close to crystallization temperature (T{sub c}) for 1 h. The effects of the annealing of the present samples on its structural and electrical properties were studied by Moessbauer spectroscopy, transmission electron micrograph (TEM), differential scanning calorimeter (DSC) and dc conductivity ({sigma}). Moessbauer spectroscopy was used in order to determine the states of iron and its hyperfine structure. The effect of nanocrystalization on the Moessbauer hyperfine parameters did not exhibit significant modifications in present glasses. However, in case of glass ceramic nanocrystals show a distinct decrease in the quadrupole splitting ({Delta}) is observed, reflecting an evident decrease in the distortion of structural units like FeO{sub 4} units. In general, the Moessbauer parameters of the nano-crystalline phase exhibit tendency to increase with PbO{sub 2} content. TEM of as-quenched glasses confirm the homogeneous and essentially featureless morphology. TEM of the corresponding glass ceramic nanocrystals indicates nanocrystals embedded in the glassy matrix with average particle size of about 32 nm. The crystallization temperature (T{sub c}) was observed to decrease with PbO{sub 2} content. The glass ceramic nanocrystals obtained by annealing at T{sub c} exhibit improvement of electrical conductivity up to four orders of magnitude than the starting glasses. This considerable improvement of electrical conductivity after nanocrystallization is attributed to formation of defective, well-conducting phases 'easy conduction paths' along the glass-crystallites interfaces.

  8. Synthesis of iron(II) dioximates with phosphine derivatives and their investigation by Moessbauer and IR spectroscopy

    SciTech Connect

    Turte, K.I.; Zubareva, V.E.; Shafranskii, V.N.; Bulgak, I.I.; Batyr, D.G.; Timokhin, B.V.; Dmitriev, V.I.

    1988-03-01

    Newly synthesized compounds with the general formula (Fe/sup II/(dioxH)/sub 2/L/sub 2/), where dioxH stands for the monodeprotonated anions of dimethylglyoxime (dmgH) diphenylglyoxime (dpgH), 1,2-cyclohexanedione dioxime (nioxH), and ..cap alpha..-furildioxime (furgH), and L stands for n-butyldiphenylphosphine (PBuPh/sub 2/) and di-n-butylphenylphosphine (PBu/sub 2/Ph), have been investigated by Moessbauer and IR spectroscopy. The Moessbauer spectra of all the compounds at 80 and 300/sup 0/K consist of doublets, whose parameters correspond to the low-spin state of iron(II). The replacement of an axial ligand of PPh/sub 3/ by PBuPh/sub 2/ or PBu/sub 2/Ph results in a decreasing the magnitude of the quadrupole splitting by approx. 30%. It has been found that PBuPh/sub 2/ and PBu/sub 2/Ph have stronger sigma-donor and ..pi..-acceptor properties in comparison to PPH/sub 3/. The data from the IR and Moessbauer spectra confirm the existence of cis influence of the ligands in the complexes investigated.

  9. The Use of Moessbauer Spectroscopy in Metallurgy

    SciTech Connect

    Forder, S.D.

    2005-04-26

    This review will present examples of the varied way in which Moessbauer spectroscopy has been used, with complementary analytical techniques, to gain information about metals and alloys, with cases chosen to illustrate how this information can be valuable to industry.The Moessbauer investigations reviewed have been divided into three categories:1) Monitoring the effect of deliberate modification of the metal by processing, either at the pre-treatment stage, e.g. metal ion etching of steel surfaces prior to coating or during the modification of structure and properties, such as the formation of Al-Fe surface alloys formed by ion implantation of Fe in Al.2) Monitoring changes in the metal not caused deliberately, i.e. the side-effects of processing. Examples reviewed include Moessbauer studies of reactor steels, and phase transformation during intensive plastic deformation. Also the Moessbauer Effect has helped to determine the cause of staining occurring on electrogalvanized steel.3) Obtaining information to enable fundamental understanding of metals and alloys. These examples include Moessbauer spectroscopy used to study the formation of intermetallic phases in industrial alloys, the influence of metal ions on iron oxide rusts and the study of quasi-crystalline alloys.The information gained has helped the improvement of properties, the monitoring of changes in structures, as well as the development of fundamental understanding of metals and alloys.

  10. Moessbauer Effects and Magnetic Properties of Mixed Valent Europium Sulfide, EuPd

    SciTech Connect

    Wakeshima, Makoto; Doi, Yoshihiro; Hinatsu, Yukio

    2001-02-15

    EuPd{sub 3}S{sub 4} with a NaPt{sub 3}O{sub 4}-type structure was investigated by X-ray diffraction, {sup 151}Eu Moessbauer spectroscopy, magnetic susceptibility, and specific heat measurements. In this compound, Eu{sup 2+} and Eu{sup 3+} ions exist in the ratio of ca. 1:1. The Debye temperatures of Eu{sup 2+} and Eu{sup 3+} were determined to be 195 and 220 K, respectively. The isomer shift of Eu{sup 2+} in this EuPd{sub 3}S{sub 4} at 300 K is largest among Eu{sup 2+} sulfides because of the compression effect of the Eu{sup 2+} sites. The temperature dependence of the isomer shifts suggests that a hopping of the electron between Eu{sup 2+} and Eu{sup 3+} occurs in EuPd{sub 3}S{sub 4}. The Eu{sup 2+} ion was found to be in the antiferromagnetic state below 3 K from both the magnetic susceptibility and specific heat measurements.

  11. Investigation of the Moessbauer Spectrum Quality as a Dependence on the Frequency of the Velocity Signal

    SciTech Connect

    Pechousek, J.

    2010-07-13

    This paper is focused on a quality characterizing the Moessbauer spectra measured for various frequencies of the velocity signal. Standard electromechanical double-loudspeaker drive and digital PID velocity controller were used for calibration spectra measurement in the frequency interval from 4 up to 100 Hz. Several parameters were evaluated for recommendation of the suitable velocity signal frequency.

  12. Synthesis and Moessbauer-spectroscopic investigation of coordination compounds of tin(IV) with ligands based on thiosemicarbazide

    SciTech Connect

    Gerbeleu, N.V.; Rochev, V.Ya.; Turte, K.I.; Bologa, O.A.; Bobkova, S.A.; Lozan, V.I.; Lavrinyuk, I.P.

    1987-03-01

    Coordination compounds of Sn(IV) of the type SnX/sub 4/L/sub 2/, where X = Cl and Br, and L stands for pyruvic acid thiosemicarbazone (pyth), carboxybenzaldehyde thiosemicarbazone (beth), and thiosemicarbazidediacetic acid (thda), respectively, have been investigated by Moessbauer spectroscopy. The gamma-resonance spectra have the form of unbroadened singlet lines with values of the isomer shifts at 92/sup 0/K equal to 0.56 for SnCl/sub 4/ (pyth)/sub 2/, 0.52 for SnCl/sub 4/ (beth)/sub 2/, 0.65 for SnCl/sub 4/ (thda)/sub 2/, 0.78 for SnBr/sub 4/ (pyth)/sub 2/, and 0.91 mm/sec for SnBr/sub 4/ (thda)/sub 2/. An analysis of the IR spectra and Moessbauer spectra led to the conclusion that in all the compounds synthesized L acts as a neutral monodentate ligand, in which the sulfur atom is the donor site.

  13. Moessbauer investigation of {sup 57}Fe doped La{sub 4}Ni{sub 3}O{sub 10{+-}}{sub y} phases

    SciTech Connect

    Carvalho, M.D.; Bassat, J.M.

    2009-01-15

    {sup 57}Fe doped La{sub 4}Ni{sub 2.97}Fe{sub 0.03}O{sub 9.95} was synthesized by a citrate method and, afterwards, successfully oxidized and reduced by electrochemical methods. The compounds obtained were investigated by X-ray diffraction, electrical measurements and Moessbauer spectroscopy. The study allowed to follow the variation of the two nickel sites environment with the oxygen stoichiometry and a deeper understanding of the electrical behavior versus oxygen non-stoichiometry was achieved. The Moessbauer study revealed that after both oxidation and reduction treatments, the major modifications were observed on the octahedra adjacent to the La{sub 2}O{sub 2} layers, while the middle octahedra of the triple perovskite block remained almost unchanged. The oxygen intercalation (oxidized treatment) takes place essentially in the La{sub 2}O{sub 2} layers and the oxygen desintercalation (reduction treatment) occurs in the octahedral sites adjacent to those layers. - Grapical abstract: Moessbauer spectra of oxidized and reduced Ruddlesden-Popper compounds La{sub 4}Ni{sub 2.97}Fe{sub 0.03}O{sub 10{+-}}{sub y}.

  14. A {sup 151}Eu Moessbauer spectroscopic and magnetic susceptibility investigation of the intermetallic compounds EuTIn (T = Zn, Pd, Pt, Au)

    SciTech Connect

    Muellmann, R.; Mosel, B.D.; Eckert, H.; Kotzyba, G.; Poettgen, R.

    1998-04-01

    The title compounds were investigated by magnetic susceptibility measurements and {sup 151}Eu Moessbauer spectroscopy. EuZnIn and EuPtIn show Curie-Weiss behavior above 60 K with experimental magnetic moments of 7.80(5) and 8.0(1) {mu}{sub B}/Eu, respectively, indicating divalent europium. The zinc compound orders antiferromagnetically at T{sub N} = 8.0(5) k and two metamagnetic transitions are detected at the critical field strengths B{sub C1} = 1.1(1) T and B{sub C2} = 2.6(2) T. At 5 K the saturation magnetic moment amounts to 7.0(1) {mu}{sub B}/Eu, suggesting a full parallel spin alignment. EuPdIn and EuAuIn order antiferromagnetically at 13.0(5) and 21.0(5) K in low external magnetic fields, respectively. The four compounds are metallic conductors. The Moessbauer measurements of the EuTIn compounds show {sup 151}Eu isomer shifts typical of divalent europium. The isomer shifts are found to linearly correlated with the closest Eu-Eu distance in the structure. Based on the Moessbauer data the onset of magnetic order is observed at T{sub N}(EuZnIn) = 9.5(5) K, T{sub N}(EuPdIn) = 15.5(5) K, T{sub N}(EuAuIn) = 20.0(5) K, and T{sub N}(EuPtIn) = 20.0(5) K, respectively. The magnetically split spectrum of EuZnIn reveals evidence of Eu site inequivalence.

  15. Effects of time and temperature of firing on Fe-rich ceramics studied by Moessbauer spectroscopy and two-dimensional {sup 1}H-nuclear magnetic resonance relaxometry

    SciTech Connect

    Casieri, Cinzia; De Luca, Francesco; Nodari, Luca; Russo, Umberto; Terenzi, Camilla; Tudisca, Valentina

    2012-10-15

    The combined effects of firing temperature and soaking time on the microstructure of iron-rich porous ceramics have been studied by {sup 57}Fe-Moessbauer spectroscopy and 2D {sup 1}H nuclear magnetic resonance (NMR) relaxometry using a single-sided probe. Examining water-saturated ceramics using the relaxation correlation method, where longitudinal (T{sub 1}) and transverse (T{sub 2}) relaxation times are measured concurrently, provides information about firing-induced changes in both porosity (related to T{sub 1}) and magnetic properties (related to T{sub 2}). Comparing the information obtained from {sup 1}H-NMR analyses with that obtained from Moessbauer spectroscopy (which characterizes changes in iron-bearing species) shows that the T{sub 1}-T{sub 2} NMR correlation technique is very sensitive to even subtle modifications in the magnetic behavior of Fe-bearing species. Moreover, the single-sided NMR approach allows us to perform millimeter-scale depth-resolved measurements, which can be used to non-invasively study the microstructural heterogeneities associated with non-uniform firing effects inside ceramics. This is in contrast to Moessbauer spectroscopy, which requires that the ceramic samples be ground.

  16. 57Fe Moessbauer Spectroscopic Investigations on the Brownmillerite Series Ca2(Fe2-xAlx)O5

    SciTech Connect

    Redhammer, G.J.; Roth, G.

    2005-04-26

    Several compounds along the Brownmillerite solid solution series Ca2Fe2-xAlxO5 with 0.0 {<=} x {<=} 1.34 have been synthesized by slow cooling from the melt and subsequent quenching. These samples were studied by Moessbauer spectroscopy at different absorber temperatures. Samples up to x = 1.00 are antiferromagnetically ordered at room temperature and can be evaluated by one octahedral and one tetrahedral magnetically split subspectra. With increasing temperature or increasing Al3+-content, respectively, the local magnetic fields decrease and finally collapse (TN = 518 K for x = 0.0 and TN = 298 K for x = 1.06, respectively). Despite the change of space group symmetry, quadrupole splittings at both positions increase almost linearly with increasing Al3+-content. This can be referred to structural changes reported. Even at low Al3+-contents, there always is a distribution of Fe3+ and Al3+ over the tetrahedral and octahedral positions in contrast to earlier results. Fe3+ prefers the octahedral and Al3+ prefers the tetrahedral positions.

  17. A Moessbauer-effect study of a series of R sub 2 Fe sub 14 C hard magnetic materials

    SciTech Connect

    Long, G.J.; Pringle, O.A.; Marasinghe, G.K. Department of Physics, University of Missouri-Rolla, Rolla, Missouri 65401 ); Grandjean, F. ); Buschow, K.H.J. )

    1991-04-15

    The {sup 57}Fe Moessbauer-effect spectra of the series of hard magnetic materials, R{sub 2}Fe{sub 14}C, where R is Nd, Gd, Tb, Dy, Ho, and Lu, have been measured at 295 K. All of these carbides exhibit uniaxial magnetic anisotropy. The spectra resemble those obtained for the related R{sub 2}Fe{sub 14}B compounds and have been fit with the model used earlier for Nd{sub 2}Fe{sub 14}B. The magnitude of the hyperfine field on each site, as a function of rare earth, parallels the Curie temperature; the maximum hyperfine fields and the maximum Curie temperature are observed for Gd{sub 2}Fe{sub 14}C. A linear correlation is observed between the hyperfine fields on the six sites in the analogous borides and carbides; however, these fields are systematically smaller in the carbides. The decrease in the tetragonal unit cell {ital c}-axis length in the carbides apparently reduces the exchange interactions between the 8{ital j} and 16{ital k} iron layers and hence reduces the moments. The isomer shift on each site decreases as the atomic number of the rare earth increases, whereas the quadrupole interactions are independent of rare earth.

  18. Analysis of Moessbauer Data from Mars: A Database and Artificial Neural Network for Identification of Iron-bearing Phases

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; deSouza, P. A.; Morris, R. V.; Klingelhoefer, G.

    2003-01-01

    The exploration of the planet Mars is one of the major goals within the Solar system exploration programs of the US-American space agency NASA and the European Space Agency ESA. In particular the search for water and life and understanding of the history of the surface and atmosphere will be the major tasks of the upcoming space missions to Mars. The miniaturized Moessbauer spectrometer MIMOS II has been selected for the NASA Mars-Exploration-Rover twin-mission to Mars in 2003 and the ESA 2003 Mars-Express Beagle 2 mission. Reduced in size and weight, in comparison to ordinary laboratory setup, the sensor head just weights approximately 400 g, with a volume of (50x50x90) cu mm, and holds two gamma-ray sources: the stronger for experiments and the weaker for calibrations. The collimator (in sample direction) also shields the primary radiation off the detectors. Around the drive four detectors are mounted. The detectors are made of Si-PIN-photodiodes in chip form (100 sq mm, thickness of 0.5 mm). The control unit is located in a separate electronics board. This board is responsible for the power supply, generation of the drive's velocity reference signal, read of the detector pulses to record the spectrum, data storage and communication with the host computer. After more than four decades from the discovery of the Moessbauer effect, more than 400 minerals were studied at different temperatures. Their Moessbauer parameters were reported in the literature, and have been recently collected in a data bank. Previous Mars-missions, namely Viking and Mars Pathfinder, revealed Si, Al, Fe, Mg, Ca, K, Ti, S and Cl to be the major constituents in soil and rock elemental composition of the red planet. More than 200 minerals already studied by Moessbauer spectroscopy contain significant amounts of these elements. A considerable number of Moessbauer studies were also carried out on meteorites and on Moon samples. Looking backward in the studies of the whole Moessbauer community

  19. Mark of the Moessbauer

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image, taken by an instrument called the microscopic imager on the Mars Exploration Rover Spirit, reveals an imprint left by another instrument, the Moessbauer spectrometer. The imprint is at a location within the rover wheel track named 'Middle of Road.' Both instruments are located on the rover's instrument deployment device, or 'arm.'

    Not only was the Moessbauer spectrometer able to gain important mineralogical information about this site, it also aided in the placement of the microscopic imager. On hard rocks, the microscopic imager uses its tiny metal sensor to determine proper placement for best possible focus. However, on the soft martian soil this guide would sink, prohibiting proper placement of the microscopic imager. After the Moessbauer spectrometer's much larger, donut-shaped plate touches the surface, Spirit can correctly calculate where to position the microscopic imager.

    Scientists find this image particularly interesting because of the compacted nature of the soil that was underneath the Moessbauer spectrometer plate. Also of interest are the embedded, round grains and the fractured appearance of the material disturbed within the hole. The material appears to be slightly cohesive. The field of view in this image, taken on Sol 43 (February 16, 2004), measures approximately 3 centimeters (1.2 inches) across.

  20. Moessbauer on Mars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken at Meridiani Planum, Mars, by the panoramic camera on the Mars Exploration Rover Opportunity shows the rover's Moessbauer spectrometer (circular device in center), located on its instrument deployment device, or 'arm.' The image was acquired on the ninth martian day or sol of the rover's mission.

  1. {sup 57}Fe and {sup 119}Sn Moessbauer Effect Study of Fe-Sn-B Amorphous Alloys

    SciTech Connect

    Miglierini, M.; Rusakov, V. S.

    2010-07-13

    Ribbons of Fe{sub 100-x}Sn{sub 5}B{sub x} (x = 15, 17, 20) metallic glass are studied using {sup 57}Fe and {sup 119}Sn Moessbauer spectrometry. The obtained Moessbauer spectra are evaluated by distributions of hyperfine magnetic fields in addition to crystalline components. The as-quenched alloys are XRD amorphous for x =15 and 17 whereas for x =20, traces of quenched-in crystallites are revealed. Progress of crystallization is followed on samples annealed for 30 min at temperatures that cover the first crystallization peak. The evolution of crystalline fraction as well as average values of hyperfine magnetic fields and isomer shifts are discussed as a function of the alloy composition and temperature of annealing.

  2. Reflectivity (visible and near IR), Moessbauer, static magnetic, and X ray diffraction properties of aluminum-substituted hematites

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Schulze, Darrell G.; Lauer, Howard V., Jr.; Agresti, David G.; Shelfer, Tad D.

    1992-01-01

    The effect of substituting iron by aluminum in polymorphs of Fe2O3 and FeOOH on their reflectivity characteristics was investigated by comparing data on visible and NIR reflectivities and on static magnetic, XRD, and Moessbauer properties for a family of aluminum-substituted hematites alpha-(Fe,Al)2O3, with compositions where the values of the Al/(Al+Fe) ratio were up to 0.61. Samples were prepared by oxidation of magnetite, dehydroxylation of goethite, and direct precipitation. The analytical methods used for obtaining diffuse reflectivity spectra (350-2200 nm), Moessbauer spectra, and static magnetic data are those described by Morris et al. (1989).

  3. Moessbauer Close-Up

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This close-up image of the Mars Exploration Rover Spirit's instrument deployment device, or 'arm,' shows the donut-shaped plate on the Moessbauer spectrometer. This image makes it easy to recognize the imprint left by the instrument in the martian soil at a location called 'Peak' on sol 43 (February 16, 2004). This image was taken by the rover's panoramic camera on sol 39 (February 11, 2004).

  4. Moessbauer spectroscopic investigations of bimetallic FeCo, FeNi, and FeRu model catalysts supported on magnesium hydroxide carbonate

    SciTech Connect

    Nagorny, K.; Bubert, S.

    1987-11-01

    FeCo, FeNi, and FeRu alloys supported on basic magnesium carbonate have been prepared by precipitation from salt solutions at 340 K onto the support using ion exchange and have been subsequently annealed for 20 h under argon. The reduction, oxidation, and sintering behavior of the samples under H/sub 2/ or CO exposure has been investigated at 723 K by means of Moessbauer spectroscopy. The comparison of the resonance absorption areas of the spectra taken at 4 and 295 K allowed the calculation of the Debye temperatures and Debye-Waller factors of the different components. From the Debye-Waller factors the relative fractions could be extrapolated to the conditions at 0 K. The kinetics of the H/sub 2/ exposure showed an increase in the reduction velocity as well as in the degree of reduction in the sequence FeCo < FeNi < FeRu. Above a critical particle diameter a phase separation occurred because of the segregation of an iron-rich phase at the surface of the alloy particles. The kinetics of the CO exposure demonstrated that with FeCo clusters iron(III) surface oxide layers form, whereas with FeNi clusters iron(II) surface oxide layers are generated. FeCo clusters with a cobalt content of 25% form only unstable surface carbides, whereas clusters with a cobalt content of about 5% form stable bulk carbides. The velocity of carbide formation increases with decreasing particle size. Based on the present data a model is proposed which explains the behavior of FeMe/magnesium hydroxide carbonates catalysts in H/sub 2/ and CO atmospheres.

  5. Map of Moessbauer Placement

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This elevation map of a soil target called 'Peak' was created from images taken by the microscopic imager located on the Mars Exploration Rover Spirit's instrument deployment device or 'arm.' The image reveals the various high and low points of this spot of soil after the Moessbauer spectrometer, another instrument on the rover's arm, was gently placed down on it. The blue areas are farthest away from the instrument; the red areas are closest. The variation in distance between blue and red areas is only 2 millimeters, or .08 of an inch. The images were acquired on sol 39 (February 11, 2004).

  6. Moessbauer Effect Study of Bi2O3. Na2O. B2O3. Fe2O3 Glass System

    SciTech Connect

    Salah, S.H.; Kashif, I.; Salem, S.M.; Mostafa, A.G.; El-Manakhly, K.A.

    2005-04-26

    Sodium-tetra-borate host glass containing both bismuth and iron cations were prepared obeying the composition (Na2B4O7)0.75 (Fe2O3)0.25-x (Bi2O3)x [where x = 0.0, 0.05, 0.10, 0.15, 0.20, and 0.25 mol.%]. X-ray diffraction indicated that all samples were in a homogeneous glassy phase. Moessbauer effect results showed that all iron ions appeared as Fe3+ ions occupying tetrahedral coordination state. The covalency of the Fe-O bond increased as bismuth oxide was gradually increased. IR measurements indicated the presence of some non-bridging oxygens and confirmed that iron ions occupy the tetrahedral coordination state. It was found also that, as Bi2O3 was gradually increased both magnetic susceptibility and specific volume decreased, while both density and molar volume increased.

  7. Study of Vitamins and Dietary Supplements Containing Ferrous Fumarate and Ferrous Sulfate Using Moessbauer Spectroscopy

    SciTech Connect

    Oshtrakh, M. I.; Novikov, E. G.; Semionkin, V. A.; Dubiel, S. M.

    2010-07-13

    A study of several samples of vitamins and dietary supplements containing ferrous fumarate and ferrous sulfate was carried out using Moessbauer spectroscopy with a high velocity resolution. A presence of ferrous and ferric impurities was revealed. Small variations of Moessbauer hyperfine parameters were found for both ferrous fumarates and ferrous sulfates in the investigated medicines.

  8. Features of the Quantitative Analysis in Moessbauer Spectroscopy

    SciTech Connect

    Semenov, V. G.; Panchuk, V. V.; Irkaev, S. M.

    2010-07-13

    The results describing the effect of different factors on errors in quantitative determination of the phase composition of studied substances by Moessbauer spectroscopy absorption are presented, and the ways of using them are suggested. The effectiveness of the suggested methods is verified by an example of analyzing standard and unknown compositions.

  9. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    SciTech Connect

    Not Available

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

  10. Electron proportional gas counter for linear and elliptical Moessbauer polarimetry

    SciTech Connect

    Tancziko, F.; Sajti, Sz.; Deak, L.; Merkel, D. G.; Endro''czi, G.; Nagy, D. L.; Bottyan, L.; Olszewski, W.; Szymanski, K.

    2010-02-15

    Design, characterization, and selected applications of a novel electron detector dedicated to conventional perpendicular- and low-angle-incidence conversion electron Moessbauer spectroscopy are presented. The setup is suitable for varying the incident angle and external magnetic fields on Moessbauer source and absorber. Test experiments were performed on {alpha}-{sup 57}Fe films using a conventional single-line {sup 57}Co(Rh) and magnetically split, {sup 57}Co({alpha}-Fe) Moessbauer sources. The integral ''blackness effect'' in conversion-electron Moessbauer spectra of {sup 57}Fe isotope-enriched absorbers is demonstrated and shown to be pronounced at shallow angles of incidence. In order to determine the alignment and sign of the hyperfine field in an isotope-enriched absorber, the blackness effect is accounted for in a semiempirical way by using single-line source/absorber experimental relative intensities determined independently. This method works with high accuracy for linear polarimetry; however it is only a rough approximation in the case of nearly circular polarimetry.

  11. Synchrotron-Radiation-Based Moessbauer Spectroscopy

    SciTech Connect

    Seto, Makoto; Masuda, Ryo; Mitsui, Takaya; Higashitaniguchi, Satoshi; Kitao, Shinji; Kobayashi, Yasuhiro; Inaba, Chika; Yoda, Yoshitaka

    2009-05-29

    We have developed a new method that yields Moessbauer absorption spectra using synchrotron radiation (SR); this method is applicable for almost all Moessbauer nuclides including those that cannot be measured by previous methods using radioisotope (RI) sources. The Moessbauer spectrum of the 68.752 keV excited state of {sup 73}Ge, which cannot be measured using a RI source, was measured using SR. Our results show that this method can be used to perform advanced Moessbauer spectroscopy measurements owing to the excellent features of SR.

  12. Moessbauer Footprint in the Soil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D image taken by the microscopic imager onboard the Mars Exploration Rover Opportunity shows a circular imprint left in the Meridiani Planum soil by the rover's Moessbauer spectrometer, an instrument located on its arm that detects iron-bearing minerals. Scientists are studying the curiously rounded grains for clues about the soil's history. The observed area is 3 centimeters (1.2 inches) across.

  13. Extraterrestrial Moessbauer Spectroscopy: More than Three Years of Mars Exploration and Developments for Future Missions

    NASA Technical Reports Server (NTRS)

    Schroeder, Christian; Klingelhoefer, Goestar; Morris, Richard V.; Rodionov, Daniel S.; Fleischer, Iris; Blumers, Mathias

    2007-01-01

    The NASA Mars Exploration Rovers (MER), Spirit and Opportunity, landed on the Red Planet in January 2004. Both rovers are equipped with a miniaturized Moessbauer spectrometer MIMOS II. Designed for a three months mission, both rovers and both Moessbauer instruments are still working after more than three years of exploring the Martian surface. At the beginning of the mission, with a landed intensity of the Moessbauer source of 150 mCi, a 30 minute touch and go measurement produced scientifically valuable data while a good quality Moessbauer spectrum was obtained after approximately eight hours. Now, after about five halflives of the sources have passed, Moessbauer integrations are routinely planned to last approx.48 hours. Because of this and other age-related hardware degradations of the two rover systems, measurements now occur less frequently, but are still of outstanding quality and scientific importance. Summarizing important Moessbauer results, Spirit has traversed the plains from her landing site in Gusev crater and is now, for the greater part of the mission, investigating the stratigraphically older Columbia Hills. Olivine in rocks and soils in the plains suggests that physical rather than chemical processes are currently active.

  14. The big and little of fifty years of Moessbauer spectroscopy at Argonne.

    SciTech Connect

    Westfall, C.

    2005-09-20

    Using radioactive materials obtained by chance, a turntable employing gears from Heidelberg's mechanical toy shops, and other minimal equipment available in post World War II Germany, in 1959 Rudolf Moessbauer confirmed his suspicion that his graduate research had yielded ground-breaking results. He published his conclusion: an atomic nucleus in a crystal undergoes negligible recoil when it emits a low energy gamma ray and provides the entire energy to the gamma ray. In the beginning Moessbauer's news might have been dismissed. As Argonne nuclear physicist Gilbert Perlow noted: ''Everybody knew that nuclei were supposed to recoil when emitting gamma rays--people made those measurements every day''. If any such effect existed, why had no one noticed it before? The notion that some nuclei would not recoil was ''completely crazy'', in the words of the eminent University of Illinois condensed matter physicist Frederich Seitz. Intrigued, however, nuclear physicists as well as condensed matter (or solid state) physicists in various locations--but particularly at the Atomic Energy Research Establishment at Harwell in Britain and at Argonne and Los Alamos in the U.S.--found themselves pondering the Moessbauer spectra with its nuclear and solid state properties starting in late 1959. After an exciting year during which Moessbauer's ideas were confirmed and extended, the physics community concluded that Moessbauer was right. Moessbauer won the Nobel Prize for his work in 1961. In the 1960s and 1970s Argonne physicists produced an increasingly clear picture of the properties of matter using the spectroscopy ushered in by Moessbauer. The scale of this traditional Moessbauer spectroscopy, which required a radioactive source and other simple equipment, began quite modestly by Argonne standards. For example Argonne hosted traditional Moessbauer spectroscopy research using mostly existing equipment in the early days and equipment that cost $100,000 by the 1970s alongside work at

  15. Moessbauer Characterization of Magnetite/Polyaniline Magnetic Nanocomposite

    SciTech Connect

    Rodriguez, Anselmo F. R.; Faria, Fernando S. E. D. V.; Lopez, Jorge L.; Mesquita, Antonio G. G.; Coaquira, Jose A. H.; Oliveira, Aderbal C.; Morais, Paulo C.; Azevedo, Ricardo B.; Araujo, Ana C. V. de; Alves, Severino Jr.; Azevedo, Walter M. de

    2010-12-02

    Aniline surface coated Fe{sub 3}O{sub 4} nanoparticles have been successfully synthesized by UV irradiation varying the time and the acid media (HCl, HNO{sub 3}, or H{sub 2}SO{sub 4}). The synthesized material represents a promising platform for application in nerve regeneration. XRD patterns are consistent with the crystalline structure of magnetite. Nevertheless, for UV irradiation times longer than 2 h, extra XRD lines reveal the presence of goethite. The mean crystallite size of uncoated particles is estimated to be 25.4 nm, meanwhile that size is reduced to 19.9 nm for the UV irradiated sample in HCl medium for 4 h. Moessbauer spectra of uncoated nanoparticles reveal the occurrence of thermal relaxation at room temperature, while the 77 K-Moessbauer spectrum suggests the occurrence of electron localization effects similar to that expected in bulk magnetite. The Mossbauer spectra of UV irradiated sample in HCl medium during 4 h, confirms the presence of the goethite phase. For this sample, the thermal relaxation is more evident, since the room temperature spectrum shows larger spectral area for the nonmagnetic component due to the smaller crystallite size. Meanwhile, the 77 K-Moessbauer spectrum suggests the absence of the electron localization effect above 77 K.

  16. Material Research Using Moessbauer Spectroscopy With Exotic Nuclei

    SciTech Connect

    Kobayashi, Y.

    2009-05-04

    We have succeeded to obtain in-beam Moessbauer spectra using a short-lived {sup 57}Mn (T{sub 1/2} = 1.45 min) probes implanted into some different types of samples, in order to study the chemical states of the excited atoms produced just after nuclear decays and/or the dynamic behaviors of isolated single atoms in a semiconductor. {sup 57}Mn was produced as a radioactive beam following a nuclear projectile-fragmentation reaction of {sup 58}Fe{sup 21+} beams (E = 63 MeV/nucleon) with Be production target, and separated by the in-flight isotope separator at the accelerators in RIKEN Nishina Center. From the temperature dependence of obtained Moessbauer parameters of the isomer shift (I.S.), the quadrupole splitting (Q.S.), and the linewidth (I), the chemical species and the dynamic behavior of the isolated atoms could be discussed. The in-beam Moessbauer technique combined with a short-lived RI beam is a very powerful tool to investigate the products after nuclear transformations and the dynamics of dilute impurities in solids.

  17. Moessbauer Spectroscopy on the Martian Surface: Predictions

    NASA Technical Reports Server (NTRS)

    Schaefer, M. W.; Dyar, M. D.

    2003-01-01

    Moessbauer spectrometers will be used on the upcoming MER/Athena and Mars Express/ Beagle 2 landers to identify and quantify relative amounts of iron-bearing minerals and determine Fe3+/Fe2+ ratios, allowing more realistic modeling of Martian mineralogy and geochemistry. To properly interpret the spectra acquired by these instruments, we must understand the Mossbauer parameters of minerals that we might expect to find on Mars. We present here a summary of predicted Fe-bearing minerals that might be observed by the MER Moessbauer spectrometers, based upon previous and our own on-going work.

  18. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Not Available

    1990-01-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  19. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1990-10-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  20. Antiferromagnetism in Co-57-doped La2CuO(4-y) studied by Moessbauer spectroscopy

    NASA Technical Reports Server (NTRS)

    Jha, S.; Mitros, C.; Lahamer, Amer; Yehia, Sherif; Julian, Glenn M.

    1989-01-01

    Moessbauer effect studies of Co-57-doped La2CuO(4-y) were performed at temperatures between 4.2 K and room temperature. These confirm the antiferromagnetic ordering of these compounds below room temperature. Temperature dependence of the quadrupole splitting shows that the hyperfine field is at an angle with the c-axis.

  1. Speciation of triphenyltin compounds using Moessbauer spectroscopy. Final report

    SciTech Connect

    Eng, G.

    1993-11-01

    Organotin compounds have been used widely as the active agent in antifouling marine paints. Organotin compounds, i.e., tributyltin compounds (TBTs) and triphenyltin compounds (TPTs) have been found to be effective in preventing the unwanted attachment and development of aquatic organisms such as barnacles, sea grass and hydroids on ships, hulls and underwater surfaces. However, these organotin compounds have been found to be toxic to non-targeted marine species as well. While speciation of tributyltins in environmental water systems has received much attention in the literature, little information concerning the speciation of triphenyltins is found. Therefore, it would be important to study the fate of TPTs in the aquatic environment, particularly in sediments, both oxic and anoxic, in order to obtain speciation data. Since marine estuaries consist of areas with varying salinity and pH, it is important to investigate the speciation of these compounds under varying salinity conditions. In addition, evaluation of the speciation of these compounds as a function of pH would give an insight into how these compounds might interact with sediments in waters where industrial chemical run-offs can affect the pH of the estuarine environment. Finally, since organotins are present in both salt and fresh water environments, the speciation of the organotins in seawater and distilled water should also be studied. Moessbauer spectroscopy would provide a preferred method to study the speciation of triphenyltins as they leach from marine paints into the aquatic environment. Compounds used in this study are those triphenyltin compounds that are commonly incorporated into marine paints such as triphenyltin fluoride (TPTF), triphenyltin acetate (TPTOAc), triphenyltin chloride (TPTCl) and triphenyltin hydroxide (TPTOH).

  2. Fe-57 Moessbauer study of tektites

    NASA Technical Reports Server (NTRS)

    Evans, B. J.; Leung, L. K.

    1976-01-01

    Moessbauer measurements were made on selected moldavite, australite, philippinite, and Georgia tektites. The spectra consist of two apparent lines, but at least two quadrupole doublets can be fitted to these spectra. The Moessbauer parameters for these doublets indicate that they arise from Fe2+ ions with local environments, which are relatively rich and relatively poor in calcium, respectively, similar to those in clinopyroxenes. No evidence for Fe3+/Fe2+ ratios above 0.01 (estimated detection limit) have been found in any tektite. Tektites are considerably more reduced than previously believed, and the extent of the reduction shows little or no variation among different types of tektites. These results limit the source materials of tektites to minerals in which the iron is uniformly highly reduced and in which the iron is contained clinopyroxene-like phases.

  3. Ordering and oxygen content effects in YBa sub 2 (Cu sub 1 minus x Fe sub x ) sub 3 O sub 7 samples observed by high-temperature Moessbauer spectroscopy

    SciTech Connect

    Saitovitch, E.B.; Scorzelli, R.B.; Azevedo, I.S.; dos Santos, C.A. )

    1990-05-01

    We report here {ital in} {ital situ} high-temperature {sup 57}Fe Moessbauer measurements on YBa{sub 2}(Cu{sub 1{minus}{ital x}}Fe{sub {ital x}}){sub 3}O{sub 7} samples in controlled oxygen atmosphere, in air, or in vacuum. In these conditions, fundamental information can be obtained related to the thermal stability of the different Fe species, as well as the mechanism of oxygen loss.

  4. Moessbauer search for ferric oxide phases in lunar materials and simulated lunar materials

    NASA Technical Reports Server (NTRS)

    Forester, D. W.

    1973-01-01

    Moessbauer studies were carried out on lunar fines and on simulated lunar glasses containing magnetic-like precipitates with the primary objective of determining how much, if any, ferric oxide is present in the lunar soils. Although unambiguous evidence of lunar Fe(3+) phases was not obtained, an upper limit was estimated from different portions of the Moessbauer spectra to be between 0.1 and 0.4 wt.% (as Fe3O4). A smaller than 62 microns fraction of 15021,118 showed 0.5 wt.% ferromagnetic iron at 300 K in as-returned condition. After heating to 650 C in an evacuated, sealed quartz tube for 1400 hours, the same sample exhibited 1 wt.% ferromagnetic iron at room temperature. An accompanying decrease in excess absorption area near zero velocity was noted. Thus, the result of the vacuum heat treatment was to convert fine grained iron to larger particles, apparently without the oxidation effects commonly reported.

  5. Investigation of dynamic ground effect

    NASA Technical Reports Server (NTRS)

    Chang, Ray Chung; Muirhead, Vincent U.

    1987-01-01

    An experimental investigation of dynamic ground effect was conducted in the Univ. of Kansas wind tunnel using delta wings of 60, 70, 75 deg sweep; the XB-70 wing; and the F-104A wing. Both static and dynamic tests were made. Test data were compared to other test data, including dynamic flight test data of the XB-70 and F-104A. Limited flow visualization test were conducted. A significant dynamic effect was found for highly swept delta wings.

  6. MOESSBAUER EFFECT IN HEMOGLOBIN WITH DIFFERENT LIGANDS.

    PubMed

    GONSER, U; GRANT, R W; KREGZDE, J

    1964-02-14

    Recoil-free nuclear gamma-ray resonance adsorption was observed in the iron-57 of blood. The spectral parameters are dependent on the ligand bound to the iron atoms in hemoglobin. The results are interpreted in terms of isomeric shifts and quad rupole splittings. PMID:14081237

  7. Moessbauer Spectrometer in the PXI/CompactPCI Modular System

    SciTech Connect

    Pechousek, Jiri; Mashlan, Miroslav; Zboril, Radek

    2005-04-26

    Two commercially available modules, a digital oscilloscope (NI 5102) and a function generator (NI 5401) in the PXI (PCI eXtension for Instrumentation) or PCI standard from National Instruments Inc., supported by the driver software, have been used for building a computer-based Moessbauer spectrometer. The RTSI (Real-Time System Integration) bus is used for synchronizing the accumulation of the detector impulses to the Moessbauer spectrum with velocity of the 'source-sample' relative motion. The amplitude selection of the impulses from the detector output is based on the use of the Waveform Peak Detection.vi function. This function is available in the graphical programming environment LabVIEW 7 Express which serves for an implementation of the virtual instrument of the Moessbauer spectrometer. Moessbauer spectra can be accumulated in the constant and variable velocity modes; moreover, there is a possibility to register gamma-ray spectra in the multichannel analyzer mode. Two types of the detectors (a NaI(Tl) and a resonance scintillation detector) have been used with the new Moessbauer spectrometer.

  8. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1993-02-01

    The QUEGS facility at MURR has produced a number of new results and demonstrated the range of potential applications of high resolution, high intensity Moessbauer scattering. This work has been carried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and other systems, manuscripts submitted on alkali halides (Phys. Rev. B) and accurate Moessbauer lineshape measurements (Phys. Rev. C), and manuscripts in preparation on glycerol, NiAl and Moessbauer spectra obtained by modulating a scattering crystal. Recently, new collaborations have been initiated which will substantially enhance our efforts. These are with W. Steiner (Vienna), G. Coddens (Saclay), and R. D. Taylor (Los Alamos). Steiner is experienced with Fe-57 Moessbauer scattering, while Coddens specializes in quasielastic neutron scattering; both of these areas naturally complement our work. R. D. Taylor has pioneered Moessbauer spectroscopy from the time of its discovery and has already made important contributions to our study of lattice dynamics and superconductivity for lead alloyed with small quantities of tin. At the same time, a significant instrument upgrade is underway, funded in part by the DOE-URIP program.

  9. Moessbauer-Fresnel zone plate as nuclear monochromator

    SciTech Connect

    Mooney, T.M.; Alp, E.E.; Yun, W.B.

    1992-06-01

    Zone plates currently used in x-ray optics derive their focusing power from (a spatial variation of) the electronic refractive index -- that is, from the collective effect of electronic x-ray-scattering amplitudes. Nuclei also scatter x rays, and resonant nuclear-scattering amplitudes, particularly those associated with Moessbauer fluorescence, can dominate the refractive index for x-rays whose energies are very near the nuclear-resonance energy. A zone plate whose Fresnel zones are filled alternately with {sup 57}Fe and {sup 56}Fe ({sup 57}Fe has a nuclear resonance of natural width {Gamma} = 4.8 nano-eV at 14.413 keV; {sup 56}Fe has no such resonance) has a resonant focusing efficiency; it focuses only those x-rays whose energies are within several {Gamma} of resonance. When followed by an absorbing screen with a small pinhole, such a zone plate can function as a synchrotron-radiation monochromator with an energy resolution of a few parts in 10{sup 12}. The energy-dependent focusing efficiency and the resulting time-dependent response of a resonant zone plate are discussed.

  10. Moessbauer spectroscopic studies of iron compounds in coal and related materials

    SciTech Connect

    Twardowska, H.

    1980-01-01

    A selection of Illinois coals, related materials, and coal process residues were investigated by means of Moessbauer spectroscopy. The purpose of the study is to characterize the iron compounds in the materials and the iron chemistry which occurs when the coal is processed. The predominant iron mineral occurring in the coals was pyrite. Marcasite also occurred in the coals although it was frequently obscured by pyrite. Jarosite was found in the weathered coals. The study also considered pyrrhotite. An important chemical process in the charring and liquefaction of coal is the conversion of pyrite to pyrrhotite. (JMT)

  11. Moessbauer studies of complex materials: Energy versus time domain

    SciTech Connect

    Planckaert, N.; Callens, R.; Demeter, J.; Temst, K.; Vantomme, A.; Laenens, B.; Meersschaut, J.; Sturhahn, W.; Kharlamova, S.

    2009-06-01

    We present a critical comparison between conventional Moessbauer spectroscopy on the one hand and energy and time resolved nuclear resonant scattering on the other hand. The three Moessbauer techniques are evaluated by the characterization of the complex magnetic structure of an Fe{sub 3}Al alloy. It is shown how the different scattering processes and detection schemes, which are involved in the respective configurations, determine the specific strengths of the three techniques and how they are optimally suited for the characterization of materials of varying complexity and reduced sizes.

  12. Prototype Backscatter Moessbauer Spectrometer for Measurement of Martian Surface Mineralogy

    NASA Technical Reports Server (NTRS)

    Shelfer, T. D.; Morris, R. V.; Agresti, D. G.; Nguyen, T.; Wills, E. L.; Shen, M. H.

    1993-01-01

    We have designed and successfully tested a prototype of a backscatter Moessbauer spectrometer (BaMS) targeted for use on the Martian surface to (1) determine oxidation states of iron, and (2) identify and determine relative abundances of iron-bearing mineralogies. No sample preparation is required to perform measurements; it is only necessary to bring sample and instrument into physical contact. The prototype meets our projected specification for a flight instrument in terms of mass, power, and volume. A Moessbauer spectrometer on the Martian surface would provide wide variety of information about the current state of the Martian surface, and this information is described.

  13. Moessbauer Spectroscopy of Martian and Sverrefjell Carbonates

    NASA Technical Reports Server (NTRS)

    Agresti, David G.; Morris, Richard V.

    2011-01-01

    Mars, in its putative "warmer, wetter: early history, could have had a CO2 atmosphere much denser than its current value of <10 mbar. The question of where all this early CO2 has gone has long been debated. Now, several instruments on Mars Exploration Rover (MER) Spirit, including its Moessbauer spectrometer MIMOS II, have identified Mg-Fe carbonate in rock outcrops at Comanche Spur in the Columbia Hills of Gusev Crater. With this finding, carbonate cements in volcanic breccia collected on Sverrefjell Volcano on Spitzbergen Island in the Svalbard Archipelago (Norway) during the AMASE project are mineralogical and possible process analogues of the newly discovered martian carbonate. We report further analyses of Mossbauer spectra from Comanche Spur and discuss their relationship to Mossbauer data acquired on Sverrefjell carbonates. The spectra were velocity calibrated with MERView and fit using MERFit. Instead of the "average temperature" Comanche spectrum (data from all temperature windows summed), we refit the Comanche data for QS within each temperature window, modeling as doublets for Fe2+(carbonate), Fe2+(olivine), and Fe3+(npOx). The temperature dependences of QS for the Comanche carbonate and for a low-Ca carbonate from Chocolate Pots in Yellowstone National Park (YNP) are shown; they are the same within error. For Comanche carbonate summed over 210-270 K, (CS, QS) = (1.23, 1.95) mm/s. The value of QS for Sverrefjell carbonate at 295 K, (CS, QS) = (1.25, 1.87) mm/s, is also plotted, and the plot shows that the QS for the Sverrefjell carbonate agrees within error with the Comanche data extrapolated to 295 K. This agreement is additional evidence that the Sverrefjell carbonates are Mossbauer analogues for the Comanche carbonates, and that both carbonates might have precipitated from solutions that became carbonate rich by passing through buried carbonate deposits.

  14. SEM, optical, and Moessbauer studies of submicrometer chromite in Allende

    NASA Astrophysics Data System (ADS)

    Housley, R. M.

    New scanning electron and optical microscope results are presented showing that sub-micrometer chromite is abundant along healed cracks and grain boundaries in Allende chondrule olivine. Some wider healed cracks also contain pentlandite and euhedral Ni3Fe grains. Also reported are Moessbauer measurements on Allende HF-HCl residues confirming a high Fe(+++)/Fe(++) ratio.

  15. SEM, optical, and Moessbauer studies of submicrometer chromite in Allende

    NASA Technical Reports Server (NTRS)

    Housley, R. M.

    1982-01-01

    New scanning electron and optical microscope results are presented showing that sub-micrometer chromite is abundant along healed cracks and grain boundaries in Allende chondrule olivine. Some wider healed cracks also contain pentlandite and euhedral Ni3Fe grains. Also reported are Moessbauer measurements on Allende HF-HCl residues confirming a high Fe(+++)/Fe(++) ratio.

  16. Molecular dynamics in cytochrome c oxidase Moessbauer spectra deconvolution

    SciTech Connect

    Bossis, Fabrizio; Palese, Luigi L.

    2011-01-07

    Research highlights: {yields} Cytochrome c oxidase molecular dynamics serve to predict Moessbauer lineshape widths. {yields} Half height widths are used in modeling of Lorentzian doublets. {yields} Such spectral deconvolutions are useful in detecting the enzyme intermediates. -- Abstract: In this work low temperature molecular dynamics simulations of cytochrome c oxidase are used to predict an experimentally observable, namely Moessbauer spectra width. Predicted lineshapes are used to model Lorentzian doublets, with which published cytochrome c oxidase Moessbauer spectra were simulated. Molecular dynamics imposed constraints to spectral lineshapes permit to obtain useful information, like the presence of multiple chemical species in the binuclear center of cytochrome c oxidase. Moreover, a benchmark of quality for molecular dynamic simulations can be obtained. Despite the overwhelming importance of dynamics in electron-proton transfer systems, limited work has been devoted to unravel how much realistic are molecular dynamics simulations results. In this work, molecular dynamics based predictions are found to be in good agreement with published experimental spectra, showing that we can confidently rely on actual simulations. Molecular dynamics based deconvolution of Moessbauer spectra will lead to a renewed interest for application of this approach in bioenergetics.

  17. Moessbauer study of microstructural and chemical changes in Fe-9Ni steel during two-phase tempering

    SciTech Connect

    Fultz, B.; Morris, J.W. Jr.

    1980-11-01

    Two-phase tempering of martensitic Fe-9Ni steel serves to enhance the low temperature toughness and forms austenite precipitates in this material. Hyperfine field effects in Fe-Ni alloys were systematized so that tempering induced chemical composition changes in the martensite could be quantified by Moessbauer spectrometry. The kinetics of segregation of alloy elements from the martensite into the fresh austenite can be determined simultaneously with the amount of austenite which was formed.

  18. YPdSn and YPd{sub 2}Sn: Structure, {sup 89}Y solid state NMR and {sup 119}Sn Moessbauer spectroscopy

    SciTech Connect

    Hoeting, Christoph; Eckert, Hellmut; Langer, Thorsten; Schellenberg, Inga; Poettgen, Rainer

    2012-06-15

    The stannides YPdSn and YPd{sub 2}Sn were synthesized by high-frequency melting of the elements in sealed tantalum tubes. Both structures were refined on the basis of single crystal X-ray diffractometer data: TiNiSi type, Pnma, a=715.4(1), b=458.8(1), c=789.1(1) pm, wR2=0.0461, 510 F{sup 2} values, 20 variables for YPdSn and MnCu{sub 2}Al type, Fm3 Macron m, a=671.44(8), wR2=0.0740, 55 F{sup 2} values, 5 parameters for YPd{sub 2}Sn. The yttrium atoms in the new stannide YPdSn are coordinated by two tilted Pd{sub 3}Sn{sub 3} hexagons (ordered AlB{sub 2} superstructure). In the Heusler phase YPd{sub 2}Sn each yttrium atom has octahedral tin coordination and additionally eight palladium neighbors. The cubic site symmetry of yttrium is reflected in the {sup 119}Sn Moessbauer spectrum which shows no quadrupole splitting. In contrast, YPdSn shows a single signal at {delta}=1.82(1) mm/s subjected to quadrupole splitting of {Delta}E{sub Q}=0.93(1) mm/s. Both compounds have been characterized by high-resolution {sup 89}Y solid state NMR spectroscopy, which indicates the presence of strong Knight shifts. The spectrum of YPd{sub 2}Sn is characterized by an unusually large linewidth, suggesting the presence of a Knight shift distribution reflecting local disordering effects. The range of {sup 89}Y Knight shifts of several binary and ternary intermetallic yttrium compounds is briefly discussed. - Graphical abstract: YPdSn and YPd{sub 2}Sn: Structure, {sup 89}Y solid state NMR and {sup 119}Sn Moessbauer spectroscopy. Highlights: Black-Right-Pointing-Pointer Synthesis and structure of ternary stannides YPdSn and YPd{sub 2}Sn. Black-Right-Pointing-Pointer {sup 119}Sn Moessbauer spectroscopic investigation of YPdSn and YPd{sub 2}Sn. Black-Right-Pointing-Pointer {sup 89}Y solid state NMR of intermetallics.

  19. Moessbauer spectroscopy study on the corrosion resistance of plasma nitrided ASTM F138 stainless steel in chloride solution

    SciTech Connect

    Souza, S.D. de; Olzon-Dionysio, M.; Basso, R.L.O.; Souza, S. de

    2010-10-15

    Plasma nitriding of ASTM F138 stainless steel samples has been carried out using dc glow discharge under 80% H{sub 2}-20% N{sub 2} gas mixture, at 673 K, and 2, 4, and 7 h time intervals, in order to investigate the influence of treatment time on the microstructure and the corrosion resistance properties. The samples were characterized by scanning electron microscopy, glancing angle X-ray diffraction and conversion electron Moessbauer spectroscopy, besides electrochemical tests in NaCl aerated solution. A modified layer of about 6 {mu}m was observed for all the nitrided samples, independent of nitriding time. The X-ray diffraction analysis shows broad {gamma}{sub N} phase peaks, signifying a great degree of nitrogen supersaturation. Besides {gamma}{sub N,} the Moessbauer spectroscopy results indicated the occurrence of {gamma}' and {epsilon} phases, as well as some other less important phases. Corrosion measurements demonstrate that the plasma nitriding time affects the corrosion resistance and the best performance is reached at 4 h treatment. It seems that the {epsilon}/{gamma}' fraction ratio plays an important role on the resistance corrosion. Additionally, the Moessbauer spectroscopy was decisive in this study, since it was able to identify and quantify the iron phases that influence the corrosion resistance of plasma nitrided ASTM F138 samples.

  20. Moessbauer Spectroscopy on the Martian Surface: Constraints on Interpretation of MER Data

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.; Schaefer, M. W.

    2003-01-01

    Moessbauer spectrometers will be used on martian landers and rovers to identify and quantify relative amounts of Fe-bearing minerals, as well as to determine their Fe(3+)/Fe(2+) ratios, allowing more realistic modeling of martian mineralogy and evolution. However, derivation of mineral modes, Fe(3+)/Fe(2+) ratios, and phase identification via Moessbauer spectroscopy (MS) does have limitations. We discuss here the exciting potential of MS for remote planetary exploration, as well as constraints on interpretation of remote Moessbauer data.

  1. Moessbauer Study and Macroscopic/Global Magnetic Behavior of Powdered Ilmenite (FeTiO{sub 3}) Sample

    SciTech Connect

    Cuda, J.; Prochazka, V.; Zboril, R.; Tucek, J.; Maslan, M.

    2010-07-13

    In this article, the commercial synthetic powdered sample of ilmenite (FeTiO{sub 3}) has been re-examined by Moessbauer spectroscopy in the paramagnetic regime from 77 K to 280 K and in a magnetically ordered state below 57 K. The effective vibrating mass and the Debye temperature was found to be (78{+-}3) amu and (359{+-}27) K, respectively. The two sextet components were used for correct fitting of the Moessbauer spectra recorded at 5 K and 45 K in an external magnetic field of 5 T. Moreover, the macroscopic magnetic measurements were carried out by an MPMS XL-7 magnetometer to determine a temperature dependence of the molar susceptibility and hysteresis loops of this sample. The Moessbauer spectra and magnetization measurements confirm that below the ordering temperature of ilmenite, it behaves as a non-ideal antiferromagnetic material with a significant magnetic hardening at low temperatures. In addition, the magnetic molar susceptibility follows a Curie-Weiss law with C{sub m=5.8x10{sup -5}Km{sup 3}/mol}, and Weiss temperature {theta}{sub p} = 30.6 K.

  2. Moessbauer Mineralogy on the Moon: The Lunar Regolith

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Korotev, Randy L..; Shelfer, Tad D.; Klingelhoefer, Goestar

    1997-01-01

    A first-order requirement for spacecraft missions that land on solid planetary objects is instrumentation for mineralogical analyses. For purposes of providing diagnostic information about naturally-occurring materials, the element iron is particularly important because it is abundant and multivalent. Knowledge of the oxidation state of iron and its distribution among iron-bearing mineralogies tightly constrains the types of materials present and provides information about formation and modification (weathering) processes. Because Moessbauer spectroscopy is sensitive to both the valence of iron and its local chemical environment, the technique is unique in providing information about both the relative abundance of iron-bearing phases and oxidation state of the iron. The Moessbauer mineralogy of lunar regolith samples (primarily soils from the Apollo 16 and 17 missions to the Moon) were measured in the laboratory to demonstrate the strength of the technique for in situ mineralogical exploration of the Moon. The regolith samples were modeled as mixtures of five iron-bearing phases: olivine, pyroxene, glass, ilmenite, and metal. Based on differences in relative proportions of iron associated with these phases, volcanic ash regolith can be distinguished from impact-derived regolith, impact-derived soils of different geologic affinity (e.g., highlands, maria) can be distinguished on the basis of their constituent minerals, and soil maturity can be estimated. The total resonant absorption area of the Moessbauer spectrum can be used to estimate total FeO concentrations.

  3. Moessbauer Study of Soil Profiles in Industrial Region of Ukraine

    SciTech Connect

    Kopcewicz, B.; Jelenska, M.; Hasso-Agopsowicz, A.; Kopcewicz, M.

    2005-04-26

    Moessbauer spectroscopy was applied to study the influence of industrial activity on soil composition. Comparing the Moessbauer spectra of separate layers for the Mariupol sampling site (highly polluted industrial region of South -- East Ukraine) we observed: i) appearance of the Fe3O4 compound at top soil layers: 16.6% of relative spectral area (RA) at (0 - 10 cm) layer, 5.3% of RA at (30 - 40 cm) layer and no magnetite component at deeper layers, ii) a significant increase of the contribution of the magnetically split spectral components: from 10.9% of RA for (120 - 130 cm) layer to 32.8% of RA for (0-10 cm) layer. The differences in RA of the magnetically split spectral components between top soil layer and the (120 - 130 cm) layer at the Homutovski steppe sampling site (non-polluted area) are much smaller, 13.7% and 9.8%, respectively. From the temperature dependence of the Moessbauer spectra it was concluded that part of the iron-containing compounds appears in the form of ultra fine particles in the superparamagnetic state. The observed increase of total concentration of the magnetic minerals for polluted sampling sites is caused by an increase of the content of coarse fraction of the magnetic particles.

  4. Determination of the Moessbauer parameters of rare-earth nitroprussides: Evidence for new light-induced magnetic excited state (LIMES) in nitroprussides

    SciTech Connect

    Rusanov, V.; Stankov, S.; Ahmedova, A.; Trautwein, A.X.

    2009-05-15

    Nitroprussides of the rare-earth elements and some mixed rare-earth-sodium nitroprussides are studied by Moessbauer spectroscopy at ambient and lower temperatures. The high precision Moessbauer measurements reveal fine changes in the electronic configurations of the nitroprusside anions. A small increase of the quadrupole splitting reveals charge polarization effects in the nitroprusside anion caused by the oblate or prolate shape of the rare-earth ion and the lanthanide contraction. Despite the very large magnetic moment of holmium a magnetic phase transition is not observed down to 300 mK. The population of the metastable states SI and SII are evidenced in europium and scandium nitroprussides, and most likely they can be populated in all rare-earth nitroprussides. No distinct correlation between the Moessbauer parameters and the decay temperatures T{sub c} of the metastable states are found. In a very thin surface layer strong color change, which remains stable at room temperature, is detected. A quadrupole doublet with Moessbauer parameters typical for Fe(III), low spin S=1/2 state is related to a new colored photoproduct. The photoproduct is called light-induced magnetic excited state (LIMES) and explained with a photochemical redox reaction, which changes the valence, spin, and magnetic state of 4f-3d bimetallic complexes. - Graphical abstract: Rare-earth nitroprussides are studied by Moessbauer spectroscopy. Population of metastable states in a thin surface layer, and another state which remains stable at room temperature, are detected. The latter is a photoproduct which is called light-induced magnetic excited state (LIMES) and explained with a photochemical redox reaction, which changes the valence, spin, and magnetic state of 4f-3d bimetallic complexes.

  5. Moessbauer spectrometer for mineralogical analysis of the Mars surface: Moessbauer source considerations

    NASA Technical Reports Server (NTRS)

    Evlanov, E. N.; Frolov, V. A.; Prilutskii, O. F.; Veselova, G. V.; Rodin, A. M.; Klingelhoefer, G.

    1993-01-01

    Development of space rocketry and cosmic instrument making has made it possible to create interplanetary stations to be sent to the solar system bodies. In the last decade of the century the planet Mars will be in the focus of planetary science problems. Russia, USA (the NASA) and Europe (the ESA) plan to do a new step in the study of the planetary system by spacecraft missions to Mars. One part of the programs of these missions is Martian surface measurements of iron, which is a dominant element in both the Martian soil and rocks (about 13 percent by weight). The chemistry of iron in space is strongly coupled to the chemistry of abundant elements (to begin with hydrogen, carbon, oxygen) and it is this coupling of chemical cycles of abundant elements that gives us the possibility of understanding some features of the chemical evolution of matter. In this connection of extremely great importance for the understanding of the evolution of the solar system are the oxidation state of the iron and its mineral composition of the Mars surface. Being highly successful, the Viking landers had no instrumentation to answer these questions. Such instrumentation has to be specifically sensitive to mineralogy. For this purpose the back scattering Moessbauer spectrometer (MS-96) was proposed to be installed on a rover to be launched on board the Russian spacecraft Mars-96 mission to Mars. Due to power and mass restrictions three systems of the device MS-96 (velocity transducer, detector and electronic components) have been extremely miniaturized in comparison to a standard system. In this paper we intend to place for consideration a radioactive source to find out what characteristics it should have to be suitable for purposes of the experiment.

  6. Moessbauer studies of two-electron centers with negative correlation energy in crystalline and amorphous semiconductors

    SciTech Connect

    Bordovsky, G. A.; Nemov, S. A.; Marchenko, A. V.; Seregin, P. P.

    2012-01-15

    The results of the study of donor U{sup -}-centers of tin and germanium in lead chalcogenides by Moessbauer emission spectroscopy are discussed. The published data regarding the identification of amphoteric U{sup -}-centers of tin in glassy binary arsenic and germanium chalcogenides using Moessbauer emission spectroscopy, and in multicomponent chalcogenide glasses using Moessbauer absorption spectroscopy are considered. Published data concerning the identification of two-atom U{sup -}-centers of copper in lattices of semimetal copper oxides by Moessbauer emission spectroscopy are analyzed. The published data on the detection of spatial inhomogeneity of the Bose-Einstein condensate in superconducting semiconductors and semimetal compounds, and on the existence of the correlation between the electron density in lattice sites and the superconducting transition temperature are presented. The principal possibility of using Moessbauer U{sup -}-centers as a tool for studying the Bose-Einstein condensation of electron pairs during the superconducting phase transition in semiconductors and semimetals is considered.

  7. Investigating Ceiling Effects in Longitudinal Data Analysis

    ERIC Educational Resources Information Center

    Wang, Lijuan; Zhang, Zhiyong; McArdle, John J.; Salthouse, Timothy A.

    2008-01-01

    Score limitation at the top of a scale is commonly termed "ceiling effect." Ceiling effects can lead to serious artifactual parameter estimates in most data analysis. This study examines the consequences of ceiling effects in longitudinal data analysis and investigates several methods of dealing with ceiling effects through Monte Carlo simulations…

  8. Development of the Fast Scintillation Detector with Programmable High Voltage Adjustment Suitable for Moessbauer Spectroscopy

    SciTech Connect

    Prochazka, R.; Frydrych, J.; Pechousek, J.

    2010-07-13

    This work is focused on a development of a compact fast scintillation detector suitable for Moessbauer spectroscopy (low energy X-ray/{gamma}-ray detection) where high counting rates are inevitable. Optimization of this part was necessary for a reliable function, better time resolution and to avoid a detector pulses pile-up effect. The pile-up effect decreases the measurement performance, significantly depends on the source activity and also on the pulse duration. Our new detection unit includes a fast scintillation crystal YAP:Ce, an R6095 photomultiplier tube, a high voltage power supply socket C9028-01 assembly, an AD5252 digital potentiometer with an I2C interface and an AD8000 ultra fast operation preamplifier. The main advantages of this solution lie in a short pulse duration (less than 200 ns), stable operation for high activities, programmable gain of the high voltage supply and compact design in the aluminum housing.

  9. Chemostratigraphy and Fe Mineralogy of the Victoria Crater Duck Bay Section: Opportunity APXS and Moessbauer Results

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Schroeder, C.; Gellert, R.; Klingelhoefer, G.; Jolliff, B. L.; Morris, R. V.

    2008-01-01

    Meridiani Planum is a vast plain of approximately horizontally bedded sedimentary rocks composed of mixed and reworked basaltic and evaporitic sands containing secondary, diagenetic minerals [e.g., 1-5]. Because bedding planes are subparallel to topography, investigation of contiguous stratigraphy requires examining exposures in impact craters. Early in the mission (sols 130-317), Opportunity was commanded to do detailed study of exposed outcrops in Endurance crater, including the contiguous Karatepe section at the point of ingress. Just over 1000 sols later and roughly 7 km to the south, the rover is being commanded to do a similar study of the Duck Bay section of Victoria crater. Here we report on the preliminary results from the Alpha Particle X-ray Spectrometer (APXS) and Moessbauer instruments.

  10. Design of the MsAa-4 Moessbauer Spectrometer

    SciTech Connect

    Blachowski, A.; Ruebenbauer, K.; Zukrowski, J.; Gornicki, R.

    2008-10-28

    An entirely new Moessbauer spectrometer MsAa-4 is currently being under design and construction. New features as compared to the basic features of the previous generation MsAa-3 spectrometer could be summarized as follows. Completely digital processing of the {gamma}-ray detector signal beyond the Gaussian shape filter/amplifier is to be implemented. The spectrometer is going to be able to accommodate external multiple detector heads. Up to 128 {gamma}-ray spectra in 16384 channels of 32-bit each and up to 512 Moessbauer spectra in 4096 channels of 32-bit each could be collected simultaneously, provided the proper external multiple detector head is used. The count-rate per single detector is limited to about 10{sup 5} counts per second in total. Improved precision of the reference function from 12-bit to 16-bit is to be provided. The reference function is stored in 8192 channels per a complete cycle. Addition of the random noise to the reference corner prism of the Michelson-Morley calibration interferometer is to be introduced to avoid spurious fringes due to the phase lock-up. An integrated universal temperature controller being able to use a variety of the temperature sensors is to be interconnected properly with the spectrometer. The spectrometer is now a stand-alone network device as it is equipped with the Ethernet connection to the outside world. Fast and high precision digital oscilloscope is to be incorporated to the spectrometer as the intrinsic unit. This oscilloscope could monitor signals at various crucial points of the internal spectrometer electronics. Modular design and use of the strict standards allows easy reconfiguration for other applications than Moessbauer spectroscopy.

  11. Moessbauer spectroscopic studies of iron-doped rutile.

    NASA Technical Reports Server (NTRS)

    Stampfl, P. P.; Travis, J. C.; Bielefeld, M. J.

    1973-01-01

    Moessbauer spectra were obtained of single crystal and powdered samples of rutile (TiO2) doped to about one percent by weight in isotopically enriched iron. It is shown that the oxidation state may be reversibly altered in situ. After reduction, the oxygen neighbors of the dopant ion are apparently shifted to accomodate the larger ferrous ion. The agreement of calculated quadrupole splittings with experimental results suggests that impurities and oxygen vacancies are uniformly distributed in powdered samples, giving the dopant ions an 'ideal lattice' local environment. The differences between the single crystal and powder sample hyperfine parameters are attributed to variations in stoichiometry, charge compensation mechanisms, or other diffusion related parameters.

  12. Fe-57 Moessbauer Spectroscopy of Fulgurites: Implications for Chemical Reduction

    NASA Technical Reports Server (NTRS)

    Sheffer, A. A.; Dyar, M. D.

    2004-01-01

    The high temperature (superliquidus) processing of silicates often results in very reduced products, such as Si-bearing Fe metal in type-1 chondrules and in lunar regolith agglutinates. Previous work on fulgurites (the glassy products of the lightning strike fusion of sand, soil, or rock) found silicon metal and iron-silicon alloys inside the silicate glass. The mechanism for this extreme reduction is not yet understood. In this work, we begin a Fe-57 Moessbauer spectroscopy study as well as continuing a microprobe study of several fulgurites in order to better constrain the extent and process of Fe reduction.

  13. High pressure Moessbauer spectroscopy in diamond anvil cells

    SciTech Connect

    Taylor, R.D. ); Pasternak, M.P. . School of Physics and Astronomy Los Alamos National Lab., NM )

    1991-01-01

    Diamond anvil cells provide a means to obtain near-hydrostatic pressures from the kilobar to the megabar regime. Moessbauer spectroscopy (MS) nicely complements the optical and X-ray measurements usually made. After a brief summary of the techniques applicable to MS, we present several examples of high pressure MS including hysteresis in the {sub {alpha}}-{sub {var epsilon}} transition in Fe, metallization in molecular crystals and the insulator-metal Mott transition in NiI{sub 2} and CoI{sub 2}. 25 refs., 7 figs.

  14. Interpretation of the Moessbauer Spectra of the Magnetic Nanoparticles in Mouse Spleen

    SciTech Connect

    Chuev, Mikhail A.; Cherepanov, Valery M.; Polikarpov, Mikhail A.; Panchenko, Vladislav Y.; Deyev, Sergey M.; Mischenko, Iliya N.; Nikitin, Maxim P.

    2010-12-02

    We have developed a stochastic model for description of relaxation effects in the system of homogeneously magnetized single-domain particles and applied the model to the analysis of Moessbauer spectra of magnetic nanoparticles (Chemicell ARA) and mouse spleen after i.v. injection into animals. We estimate that the fraction of exogenous iron in nanoparticles in the mouse spleen 3 months after injection was 0.27{+-}0.03. The spectra of the residual nanoparticles in the spleen had almost the same isomer shift but smaller mean hyperfine magnetic field values indicating decrease in the magnetic anisotropy energy (size) of the particles compared to the initial ones in the course of biodegradation. Concentration of ferritin-like iron was about three-fold higher than that in the spleen of untreated animals showing ferritin-like forms in the mouse spleen.

  15. Moessbauer and SANS Studies of Anti-Invar Fe-Ni-C Alloy under Magnetic Field

    SciTech Connect

    Nadutov, V. M.; Kosintsev, S. G.; Svystunov, Ye. O.; Garamus, V. M.; Willumeit, R.; Eckerlebe, H.; Ericsson, T.; Annersten, H.

    2010-07-13

    Anti-Invar effect in the f.c.c.-Fe-25.3%Ni-C alloy was revealed, i.e., enhanced thermal expansion coefficient (TEC)({approx}20x10{sup -6} K{sup -1}) which was accompanied by almost temperature-insensitive behavior in a temperature range of 122-525 K that was considerably expanded to the low temperature range due to alloying with carbon. The Moessbauer and small-angle neutron scattering (SANS) experiments with the varying temperature and in an external magnetic field of 1.5-5 T have revealed an existence of inhomogeneous magnetic order in anti-Invar alloy below and above the magnetic transition point. The anti-Invar behavior correlates with the thermally induced change in the magnetic order and interspin interaction.

  16. Moessbauer spectroscopy of the SNC meteorite Zagami

    NASA Technical Reports Server (NTRS)

    Agerkvist, D. P.; Vistisen, L.

    1993-01-01

    We have performed Mossbauer spectroscopy on two different pieces of the meteorite Zagami belonging to the group of SNC meteorites. In one of the samples we found a substantial amount of olivine inter grown with one kind of pyroxene, and also another kind of pyroxene very similar to the pyroxene in the other sample we examined. Both samples showed less than 1 percent of Fe(3+) in the silicate phase. The group of SNC meteorites called shergottites, to which Zagami belongs, are achondrites whose texture, mineralogy and composition resembles those of terrestrial diabases. The results from the investigation are presented.

  17. Moessbauer Spectroscopy of Soils and Rocks at Gusev Crater and Meridiani Planum

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Morris, R. V.; Bernhardt, B.; Schroeder, C.; Rodionov, D.; deSouza, P. A., Jr.; Yen, A.; Renz, F.; Wdowiak, T.; Squyres, S.

    2004-01-01

    For the first time in history a Moessbauer spectrometer was placed on the surface of another planet. The miniaturized Moessbauer spectrometer MIMOS II is part of the Athena payload of NASA's twin Mars Exploration Rovers (MER) Spirit,and Opportunity. It determines the Fe-bearing mineralogy of Martian soils and rocks at the Rovers respective landing sites, Gusev crater and Meridiani Planum. First results of soil and rock measurements at both landing sites confirm a generally basaltic composition of Martian surface materials.

  18. Moessbauer spectroscopy studies of iron-catalysts used in Fischer-Tropsch (FT) processes. Quarterly technical progress report, January--March, 1995

    SciTech Connect

    Huffman, G.P.; Rao, K.R.P.M.

    1995-10-01

    Moessbauer spectroscopy investigations were carried out on 14 iron-based catalysts during the period under review. The catalyst 100Fe/4.4Si/0.71K (all atomic ratios) was subjected to activation first in syngas and subsequently in CO gas atmosphere. Fischer-Tropsch (FT) synthesis was carried out on the above catalyst. Another catalyst 100Fe/4.4Si/2.6Cu/0.71K (all atomic ratios) activated in syngas and subjected to FT synthesis was also studied to understand the effect of added Cu on the phase distribution and its effect on the FT activity. The following trends were observed: (1) activation of the catalyst in syngas, H{sub 2}/CO, lead to the formation of Fe{sub 3}O{sub 4} and no carbides were formed, the FT activity was found to be low at 9--12% (H{sub 2}+CO) conversion; (2) activation of the catalyst in CO for 22hrs lead to the formation of 33% of {chi}-carbide and the FT activity was found to be high at 88% maximum; (3) addition of copper to the catalyst has improved the FT activity for those catalysts pretreated in syngas at elevated pressures.

  19. Iron Moessbauer spectroscopy: Superparamagnetism in hydrothermal vents and the search for evidence of past life on Mars

    NASA Technical Reports Server (NTRS)

    Agresti, David G.; Wdowiak, Thomas J.

    1992-01-01

    In view of the demonstrated value of Iron Moessbauer Spectroscopy (FeMS) in the study of extraterrestrial iron and the fact that, after silicon and oxygen, iron is the most abundant element on the surface of Mars, we proposed, and have under development, a backscatter Moessbauer spectrometer with x ray fluorescence capability (BaMS/XRF) for use on Mars as a geophysical prospecting instrument. Specifically, we have proposed BaMS/XRF as part of the geochemistry instrumentation on NASA's Mars Environment Survey (MESUR) mission. BaMS/XRF will have applications in: (1) the study of past environments through the examination of sedimentary material; (2) the study of the contemporary Martian environment; and (3) the study of iron-containing minerals of possible biogenic origin. Development of a reference library from a geophysical point of view for putative Martian surface materials at appropriate temperatures is now underway. We carried out preliminary optical reflectance and FeMS measurements on mineral products (iron oxyhydroxides) of deep-sea hydrothermal activity. Various aspects of this investigation are presented.

  20. Moessbauer spectroscopy and scanning electron microscopy of the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Brown, Christopher L.; Oliver, Frederick W.; Hammond, Ernest C., Jr.

    1989-01-01

    Meteorites provide a wealth of information about the solar system's formation, since they have similar building blocks as the Earth's crust but have been virtually unaltered since their formation. Some stony meteorites contain minerals and silicate inclusions, called chondrules, in the matrix. Utilizing Moessbauer spectroscopy, we identified minerals in the Murchison meteorite, a carbonaceous chondritic meteorite, by the gamma ray resonance lines observed. Absorption patterns of the spectra were found due to the minerals olivine and phyllosilicate. We used a scanning electron microscope to describe the structure of the chondrules in the Murchison meteorite. The chondrules were found to be deformed due to weathering of the meteorite. Diameters varied in size from 0.2 to 0.5 mm. Further enhancement of the microscopic imagery using a digital image processor was used to describe the physical characteristics of the inclusions.

  1. The Miniaturized Moessbauer Spectrometer MIMOS II for the Asteroid Redirect Mission(ARM): Quantative Iron Mineralogy And Oxidation States

    NASA Technical Reports Server (NTRS)

    Schroeder, C.; Klingelhoefer, G; Morris, R. V.; Yen, A. S.; Renz, F.; Graff, T. G.

    2016-01-01

    The miniaturized Moessbauer spectrometer MIMOS II is an off-the-shelf instrument with proven flight heritage. It has been successfully deployed during NASA’s Mars Exploration Rover (MER) mission and was on-board the UK-led Beagle 2 Mars lander and the Russian Phobos-Grunt sample return mission. A Moessbauer spectrometer has been suggested for ASTEX, a DLR Near-Earth Asteroid (NEA) mission study, and the potential payload to be hosted by the Asteroid Redirect Mission (ARM). Here we make the case for in situ asteroid characterization with Moessbauer spectroscopy on the ARM employing one of three available fully-qualified flight-spare Moessbauer instruments.

  2. Investigations into the common ion effect

    NASA Astrophysics Data System (ADS)

    Valdeavella, C. V.; Perkyns, John S.; Pettitt, B. Montgomery

    1994-09-01

    The molecular origins of the common ion effect and the salting out of nonpolar molecules from aqueous solutions are investigated. Thermodynamic stability criteria for a common ion mixture in a polar solvent are derived. Kirkwood-Buff statistical thermodynamics is used to make the connection with the microscopic pair correlation functions. The observed sensitivity of the compositional stability with respect to ionic strength indicates that a demixing transition is the primary cause of the instability for the common ion effect for our model Lennard-Jones plus Coulomb Hamiltonian.

  3. Determination of the Lamb-Moessbauer factors of LiFePO{sub 4} and FePO{sub 4} for electrochemical in situ and operando measurements in Li-ion batteries

    SciTech Connect

    Aldon, L.

    2010-01-15

    {sup 57}Fe Moessbauer spectroscopy is a powerful tool to investigate redox reactions during in electrochemical lithium insertion/extraction processes. Electrochemical oxidation of LiFe{sup II}PO{sub 4} (triphylite) in Li-ion batteries results in Fe{sup III}PO{sub 4} (heterosite). LiFePO{sub 4} was synthesized by solid state reaction at 800 deg. C under Ar flow from Li{sub 2}CO{sub 3}, FeC{sub 2}O{sub 4}.2H{sub 2}O and NH{sub 4}H{sub 2}PO{sub 4} precursors in stoichiometric composition. FePO{sub 4} was prepared from chemical oxidation of LiFePO{sub 4} using bromine as oxidative agent. For both materials a complete {sup 57}Fe Moessbauer study as a function of the temperature has been carried out. The Debye temperatures are found to be theta{sub M}=336 K for LiFePO{sub 4} and theta{sub M}=359 K for FePO{sub 4}, leading to Lamb-Moessbauer factors f{sub 300K}=0.73 and 0.77, respectively. These data will be useful for a precise estimation of the relative amounts of each species in a mixture. - Graphical abstract: Relative amount of FePO{sub 4} obtained by Moessbauer and electrochemical data. We have corrected Moessbauer spectral intensities with our f factor of both LiFePO{sub 4} and FePO{sub 4}. Open (filled) squares correspond to values obtained during charging (discharging) process. The dashed line, given as a guideline for the eye, corresponds to the ideal case were amounts deduced from different experimental measurements are equal.

  4. NMR investigation of the quantum pigeonhole effect

    NASA Astrophysics Data System (ADS)

    V. S., Anjusha; Hegde, Swathi S.; Mahesh, T. S.

    2016-02-01

    NMR quantum simulators have been used for studying various quantum phenomena. Here, using a four-qubit NMR quantum simulator, we investigate the recently postulated quantum pigeonhole effect. In this phenomenon, a set of three particles in a two-path interferometer often appears to be in such a superposition that no two particles can be assigned a single path, thus exhibiting the nonclassical behavior. In our experiments, quantum pigeons are emulated by three nuclear qubits whose states are probed jointly and noninvasively by an ancillary spin. The experimental results are in good agreement with quantum theoretical predictions.

  5. The Miniaturized Moessbauer Spectrometer MIMOS II of the Athena Payload for the 2003 MER Missions

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Morris, R. V.; deSouza, P. A., Jr.; Bernhardt, B.

    2003-01-01

    A first-order requirement of spacecraft missions that land on Mars is instrumentation for in situ mineralogical analysis. Moessbauer Spectroscopy is a powerful tool for quantitative analysis of Fe-bearing materials. The Athena Moessbauer spectrometer MIMOS II on the martian surface will provide: (1) identification of iron-bearing phases (e.g., oxides, silicates, sulfides, sulfates, and carbonates), (2) quantitative measurement of the distribution of iron among its oxidation states (e.g., Fe(2+)/Fe(3+) ratio), and (3) quantitative measurement of the distribution of iron among iron-bearing phases (e.g., the relative proportions of iron in olivine, pyroxene, and magnetite in a basalt) in rocks and soils. Moessbauer data will also be highly complementary with chemical analyses from the APXS and the Mini-TES compositional data. Mars is a particularly good place to do Moessbauer mineralogy because its surface is iron rich (approx. 20% Fe as Fe2O3). Moessbauer spectrometers that are built with backscatter measurement geometry require no sample preparation, a factor important for in situ planetary measurements.

  6. Investigation of multiple scattering effects in aerosols

    NASA Technical Reports Server (NTRS)

    Deepak, A.

    1980-01-01

    The results are presented of investigations on the various aspects of multiple scattering effects on visible and infrared laser beams transversing dense fog oil aerosols contained in a chamber (4' x 4' x 9'). The report briefly describes: (1) the experimental details and measurements; (2) analytical representation of the aerosol size distribution data by two analytical models (the regularized power law distribution and the inverse modified gamma distribution); (3) retrieval of aerosol size distributions from multispectral optical depth measurements by two methods (the two and three parameter fast table search methods and the nonlinear least squares method); (4) modeling of the effects of aerosol microphysical (coagulation and evaporation) and dynamical processes (gravitational settling) on the temporal behavior of aerosol size distribution, and hence on the extinction of four laser beams with wavelengths 0.44, 0.6328, 1.15, and 3.39 micrometers; and (5) the exact and approximate formulations for four methods for computing the effects of multiple scattering on the transmittance of laser beams in dense aerosols, all of which are based on the solution of the radiative transfer equation under the small angle approximation.

  7. Moessbauer Study of Electrodeposited Fe/Fe-Oxide Multilayers

    SciTech Connect

    Kuzmann, E.; Homonnay, Z.; Klencsar, Z.; Vertes, A.; Lakatos-Varsanyi, M.; Miko, A.; Varga, L.K.; Kalman, E.; Nagy, F.

    2005-04-26

    Iron has been deposited electrochemically by short current pulses in Na-saccharin containing FeII-chloride and sulphate solution electrolytes. Combined electrochemical techniques with initial pulse plating of iron nanolayer and its subsequent anodic oxidation under potential control have been used for production of Fe/Fe-oxide multilayers. 57Fe CEM spectra of pulse plated iron revealed the presence of a minor doublet attributed mainly to {gamma}-FeOOH in addition to the dominant sextet of {alpha}-iron. In the case of anodically oxidized pulse plated iron and of samples after repeated deposition of anodically oxidized pulse plated iron an additional minor doublet, assigned to ferrous chloride, also appears in the Moessbauer spectra. A significant change in the magnetic anisotropy of {alpha}-iron was observed with the anodic oxidation. The thickness of the layers were estimated from the CEM spectrum data by a modified computer program of the Liljequist method. The coercive field and the power loss versus frequency data showed that the pulse plated iron cores are good inductive elements up to several kHz frequencies.

  8. Moessbauer spectroscopy of Mg(0.9)Fe(0.1)SiO3 perovskite

    NASA Technical Reports Server (NTRS)

    Jeanloz, Raymond; O'Neill, Bridget; Pasternak, Moshe P.; Taylor, R. D.; Bohlen, Steven R.

    1992-01-01

    Ambient pressure Moessbauer spectra of Mg(0.9)Fe-57(0.1)SiO3 perovskite synthesized at pressure-temperature conditions of about 50 GPa and 1700 K show that the iron is entirely high-spin Fe(2+) and appears to be primarily located in the octahedral site within the crystal structure. We observe broad Moessbauer lines, suggesting a distribution of electric-field gradients caused by disorder associated with the Fe ions. Also, the perovskite exhibits magnetic ordering at temperatures lower than 5 K, implying that there is a magnetic contribution to the absolute ('third-law') entropy of this phase.

  9. Moessbauer spectroscopy evidence of a spinodal mechanism for the thermal decomposition of fcc FeCu

    SciTech Connect

    Crespo, P. |; Barro, M.J.; Hernando, A.; Escorial, A.G.; Menendez, N.; Tornero, J.D.; Barandiaran, J.M.

    1998-07-24

    Moessbauer spectroscopy shows the existence of compositional fluctuations, where different Fe environments coexist, during decomposition upon heat treatment of metastable f.c.c. FeCu solid solution. The presence of isolated Fe atoms in the Cu matrix, f.c.c. Fe{sub rich}Cu, f.c.c. FeCu{sub rich} and b.c.c. Fe has been detected in early decomposition stages. At later decomposition stages, low temperature Moessbauer spectroscopy indicates the presence of a broad distribution of Curie temperatures, coexisting with isolated Fe atoms in the Cu matrix, f.c.c. Fe and b.c.c. Fe.

  10. Cronstedtite and iron sulfide mineralogy of CM-type carbonaceous chondrites from cryogenic Moessbauer spectra

    NASA Technical Reports Server (NTRS)

    Fisher, Duncan S.; Burns, Roger G.

    1993-01-01

    Determinations of oxidation states and the crystal chemistry of iron-bearing minerals in CM meteorites by Moessbauer spectroscopy are complicated by thermally-induced electron hopping in cronstedtite and by ill-defined contributions from the hydrous iron sulphide phase believed to be tochilinite. Moessbauer spectral measurements at 30 K of several cronstedtite and tochilinite specimens have enabled modal proportions of these minerals, as well as Fe(3+)/Fe(2+) ratios, to be determined quantitatively for a suite of CM-type carbonaceous chondrites that included Murchison, Murray, Cold Bokkeveld, ALH 83100, and LEW 90500.

  11. TEM and Moessbauer Study of Nano Sized Fe{sub 2}MnAl Flakes

    SciTech Connect

    Vinesh, A.; Sudheesh, V. D.; Lakshmi, N.; Venugopalan, K.

    2011-07-15

    Magnetic and structural properties of L21 ordered Fe{sub 2}MnAl Heusler alloy have been studied by X-ray diffraction, Transmission electron microscopy (TEM), Moessbauer spectroscopy and DC magnetization. Structural texturing induced by ball milling is destroyed on heating while Moessbauer and DC magnetization studies show magnetic texturing persists after thermal treatment. TEM shows large distribution in particle size with an average size of 27 nm. Thermal annealing of ball milled sample results L2{sub 1} ordering and the needle shaped particle contributes spin texturing.

  12. Investigating expectation effects using multiple physiological measures

    PubMed Central

    Siller, Alexander; Ambach, Wolfgang; Vaitl, Dieter

    2015-01-01

    The study aimed at experimentally investigating whether the human body can anticipate future events under improved methodological conditions. Previous studies have reported contradictory results for the phenomenon typically called presentiment. If the positive findings are accurate, they call into doubt our views about human perception, and if they are inaccurate, a plausible conventional explanation might be based on the experimental design of the previous studies, in which expectation due to item sequences was misinterpreted as presentiment. To address these points, we opted to collect several physiological variables, to test different randomization types and to manipulate subjective significance individually. For the latter, we combined a mock crime scenario, in which participants had to steal specific items, with a concealed information test (CIT), in which the participants had to conceal their knowledge when interrogated about items they had stolen or not stolen. We measured electrodermal activity, respiration, finger pulse, heart rate (HR), and reaction times. The participants (n = 154) were assigned randomly to four different groups. Items presented in the CIT were either drawn with replacement (full) or without replacement (pseudo) and were either presented category-wise (cat) or regardless of categories (nocat). To understand how these item sequences influence expectation and modulate physiological reactions, we compared the groups with respect to effect sizes for stolen vs. not stolen items. Group pseudo_cat yielded the highest effect sizes, and pseudo_nocat yielded the lowest. We could not find any evidence of presentiment but did find evidence of physiological correlates of expectation. Due to the design differing fundamentally from previous studies, these findings do not allow for conclusions on the question whether the expectation bias is being confounded with presentiment. PMID:26500600

  13. Investigating expectation effects using multiple physiological measures.

    PubMed

    Siller, Alexander; Ambach, Wolfgang; Vaitl, Dieter

    2015-01-01

    The study aimed at experimentally investigating whether the human body can anticipate future events under improved methodological conditions. Previous studies have reported contradictory results for the phenomenon typically called presentiment. If the positive findings are accurate, they call into doubt our views about human perception, and if they are inaccurate, a plausible conventional explanation might be based on the experimental design of the previous studies, in which expectation due to item sequences was misinterpreted as presentiment. To address these points, we opted to collect several physiological variables, to test different randomization types and to manipulate subjective significance individually. For the latter, we combined a mock crime scenario, in which participants had to steal specific items, with a concealed information test (CIT), in which the participants had to conceal their knowledge when interrogated about items they had stolen or not stolen. We measured electrodermal activity, respiration, finger pulse, heart rate (HR), and reaction times. The participants (n = 154) were assigned randomly to four different groups. Items presented in the CIT were either drawn with replacement (full) or without replacement (pseudo) and were either presented category-wise (cat) or regardless of categories (nocat). To understand how these item sequences influence expectation and modulate physiological reactions, we compared the groups with respect to effect sizes for stolen vs. not stolen items. Group pseudo_cat yielded the highest effect sizes, and pseudo_nocat yielded the lowest. We could not find any evidence of presentiment but did find evidence of physiological correlates of expectation. Due to the design differing fundamentally from previous studies, these findings do not allow for conclusions on the question whether the expectation bias is being confounded with presentiment. PMID:26500600

  14. Experimental investigations of the Electrical Asymmetry Effect

    NASA Astrophysics Data System (ADS)

    Schulze, Julian; Schuengel, Edmund; Luggenhoelscher, Dirk; Czarnetzki, Uwe; Donko, Zoltan

    2009-10-01

    In 2008 a method to generate a variable DC self bias even in geometrically symmetric capacitively coupled radio frequency (CCRF) discharges was proposed theoretically [1]. If the discharge is operated at a fundamental frequency and its second harmonic, it has been predicted that the resulting DC self bias can be adjusted by the phase angle between the applied voltage harmonics. A PIC simulation demonstrated that this Electrical Asymmetry Effect (EAE) allows separate control of the energy and flux of ions at the electrode surfaces. Here the EAE and the related separate control of ion energy and flux is investigated experimentally in a geometrically symmetric CCRF discharge operated at 13.56 MHz and 27.12 MHz with variable phase shift between the harmonics in argon at different pressures. The DC self bias, the energy as well as the flux of ions at the grounded electrode are measured. The experimental results verify the theoretical predictions and show that ion energy and flux can be controlled separately. The EAE is optimized by choosing low and high frequency voltage amplitudes that yield the strongest relative DC self bias. [4pt] [1] Heil B G et al. 2008 J. Phys. D 41 165202

  15. An Overview of Moessbauer Mineralogy at Gusev Crater, Mars

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Schroeder, C.; Rodionov, D.; Yen, A.

    2006-01-01

    The Mars Exploration Rover (MER) Spirit landed on the plains of Gusev Crater on 4 January 2004 [1]. The scientific objective of the Moessbauer (MB) spectrometer on Spirit is to provide quantitative information about the distribution of Fe among its oxidation and coordination states, identification of Fe-bearing phases, and relative distribution of Fe among those phases. The speciation and distribution of Fe in Martian rock and soil constrains the primary rock types, redox conditions under which primary minerals crystallized, the extent of alteration and weathering, the type of alteration and weathering products, and the processes and environmental conditions for alteration and weathering.We discuss the Fe-bearing phases detected by Spirit s MB instrument during its first 540 sols of exploration [2,3]. Spirit roved eastward across the plains from its landing site to the Columbia Hills during the first approx.150 sols. Rocks are unweathered to weakly weathered olivine basalt, with olivine, pyroxene (Ol > Px), magnetite (Mt), and minor hematite (Hm) and nanophase ferric oxide (npOx) as their primary Fe-bearing minerals. Soils are generally similar basaltic materials, except that the proportion of npOx is much higher (up to approx.40%). NpOx is an oct-Fe3+ alteration product whose concentration is highest in fine-grained soils and lowest in rock interiors exposed by grinding with the Rock Abrasion Tool (RAT). Spirit explored the lower slopes of the Columbia Hills (West Spur) during sols approx.150-320. West Spur rocks are highly altered, even for interior surfaces exposed by grinding (Fe3+/FeT approx.0.56-0.84). High concentrations of npOx, Hm, and Mt are present. One rock (Clovis) contains significant quantities of goethite (alpha-FeOOH; approx.40% of total Fe). The detection of goethite is very significant because it is a mineralogical marker for aqueous alteration.

  16. Elementary diffusion jump of iron atoms in intermetallic phases studied by Moessbauer spectroscopy; 1: Fe-Al close to equiatomic stoichiometry

    SciTech Connect

    Vogl, G.; Sepiol, B. . Inst. fuer Festkoerperphysik)

    1994-09-01

    The authors have studied the quasielastic broadening of the [sup 57]Fe Moessbauer resonance in the intermetallic compound FeAl in order to determine the diffusion jump mechanism of the Fe atoms. From the angular dependence of the line broadening relative to an oriented single crystal they deduce that the Fe atoms jump effectively to different neighbor sites on the Fe sublattice. The jump is, however, not a direct one, but rather a combination of a jump into a nearest neighbor vacancy--leading to short-time occupation of an antistructure site on the Al sublattice--and a jump into a vacancy back on the Fe sublattice.

  17. Some Improvements in the Design of a CA/CV Moessbauer Velocity Drive

    SciTech Connect

    Seberini, Milan

    2008-10-28

    A constant velocity Moessbauer drive was built with velocity range {+-}15 mm/s and velocity resolution 0.005 mm/s. Based on good experience with its performance, a new universal CA/CV drive was designed. The new drive is supposed to have velocity range of {+-}80 mm/s with a velocity resolution below 0.002 mm/s.

  18. Moessbauer medium with a hidden nuclear population inversion and negative absorption of gamma quanta

    SciTech Connect

    Rivlin, Lev A

    2011-06-30

    We consider physical foundations of an eventual experiment aimed at observing stimulated gamma-photon emission of long-lived Moessbauer isomers through selective frequency modulation of gamma-resonances establishing hidden population inversion without exceeding the number of excited nuclei over unexcited ones and without additional pumping. The examples of suitable nuclei and numerical estimates of the parameters are presented. (active media)

  19. Moessbauer study in thin films of FeSi2 and FeSe systems

    NASA Technical Reports Server (NTRS)

    Escue, W. J.; Aggarwal, K.; Mendiratta, R. G.

    1978-01-01

    Thin films of FeSi2 and FeSe were studied using Moessbauer spectroscopy information regarding dangling bond configuration and nature of crystal structure in thin films was derived. A significant influence of crystalline aluminum substrate on film structure was observed.

  20. Use of Moessbauer spectroscopy to study reaction products of polyphenols and iron compounds

    SciTech Connect

    Gust, J. ); Suwalski, J. )

    1994-05-01

    Moessbauer spectroscopy was used to study parameters of the reaction products of iron compounds (Fe[sup III]) and polyphenols with hydroxyl (OH) groups in ortho positions. Polyphenols used in the reaction were catechol, pyrogallol, gallic acid, and oak tannin. The Fe-containing compounds were hydrated ferric sulfate (Fe[sub 2][SO[sub 4

  1. Investigating the Effectiveness of Classroom Diagnostic Tools

    ERIC Educational Resources Information Center

    Schultz, Robert K.

    2012-01-01

    The primary purposes of the study are to investigate what teachers experience while using the Classroom Diagnostic Tools (CDT) and to relate those experiences to the rate of growth in students' mathematics achievement. The CDT contains three components: an online computer adaptive diagnostic test, interactive web-based student reports, and…

  2. Moessbauer study of iron-carbide growth and Fischer-Tropsch activity

    SciTech Connect

    Rao, K.R.P.M.; Huggins, F.E.; Huffman, G.P.

    1995-12-31

    There is a need to establish a correlation between the Fischer-Tropsch (FT) activity of an iron-based catalyst and the catalyst phase during FT synthesis. The nature of iron phases formed during activation and FT synthesis is influenced by the gas used for activation. Moessbauer investigations of iron-based catalysts subjected to pretreatment in gas atmospheres containing mixtures of CO, H{sub 2}, and He have been carried out. Studies on UCI 1185-57 catalyst indicate that activation of the catalyst in CO leads to the formation of 100% magnetite and the magnetite formed gets rapidly converted to at least 90% of x-Fe{sub 5}C{sub 2} during activation. The x-Fe{sub 5}C{sub 2} formed during activation gets partly (= 25%) converted back to Fe{sub 3}O{sub 4} during FT synthesis and both x-Fe{sub 5}C{sub 2} and Fe{sub 3}O{sub 4} reach constant values. On the other hand, activation of the catalyst in synthesis gas leads to formation of Fe{sub 3}O{sub 4} and which is slowly converted to x-Fe{sub 5}C{sub 2} and e-Fe{sub 2.2}C during activation, and both carbide phases increase slowly during FT synthesis. FT synthesis activity is found to give rise to {approx} 70% (H2+CO) conversion in the case of CO activated catalyst as compared to {approx} 20% (H2+CO) conversion in the case of synthesis gas-activated catalyst.

  3. Experimental investigation of dynamic ground effect

    NASA Technical Reports Server (NTRS)

    Lee, Pai-Hung; Lan, C. Edward; Muirhead, Vincent U.

    1989-01-01

    A 60-degree delta wing, an F-106B, and an XB-70 model with and without flap deflections were tested in static and dynamic ground effect in the 36-by-51-inch subsonic wind tunnel at the University of Kansas. Dynamic ground effect was measured with movable sting support. For flow visualization, a tufted wire grid was mounted on the movable sting behind the model. Test results showed that lift and drag increments in dynamic ground effect were always lower than static values. Effect of the trailing edge flap deflections on lift increments was slight. The fuselage reduced the lift increments at a given ground height. From flow visualization under static conditions, the vortex core was seen to enlarge as the ground was approached.

  4. An Investigation into Effectiveness of Peer Feedback

    ERIC Educational Resources Information Center

    Lin, Grace Hui Chin; Chien, Paul Shih Chieh

    2009-01-01

    Copious researches argue the effectiveness of peer-correction in writing courses (e.g., Connor & Asenavage, 1994). Also, Coit (2004) mentions using peer feedback for correcting articles through a student-centered environment is a beneficial pedagogy to extend learners' academic-style writing practice. Therefore, this study focused on…

  5. Investigating the Compton Effect with a Spreadsheet.

    ERIC Educational Resources Information Center

    Kinderman, Jesusa Valdez

    1992-01-01

    Describes a computer simulation of the Compton effect designed to lead students to discover (1) the relationship of the electron's final kinetic energy to its angle of scattering and (2) the relationship between the scattering angles of the outgoing electron and photon. (MDH)

  6. Cavitation erosion - scale effect and model investigations

    NASA Astrophysics Data System (ADS)

    Geiger, F.; Rutschmann, P.

    2015-12-01

    The experimental works presented in here contribute to the clarification of erosive effects of hydrodynamic cavitation. Comprehensive cavitation erosion test series were conducted for transient cloud cavitation in the shear layer of prismatic bodies. The erosion pattern and erosion rates were determined with a mineral based volume loss technique and with a metal based pit count system competitively. The results clarified the underlying scale effects and revealed a strong non-linear material dependency, which indicated significantly different damage processes for both material types. Furthermore, the size and dynamics of the cavitation clouds have been assessed by optical detection. The fluctuations of the cloud sizes showed a maximum value for those cavitation numbers related to maximum erosive aggressiveness. The finding suggests the suitability of a model approach which relates the erosion process to cavitation cloud dynamics. An enhanced experimental setup is projected to further clarify these issues.

  7. Investigations of fission characteristics and correlation effects

    NASA Astrophysics Data System (ADS)

    Gundorin, N. A.; Zeinalov, Sh. S.; Kopach, Yu. N.; Popov, A. B.; Furman, V. I.

    2016-07-01

    We review the experimental results on the P-even and P-odd angular correlations of fission fragments in the fission of the 235U and 239Pu nuclei induced by unpolarized and polarized resonance neutrons, and on the TRI and ROT effects in the ternary and binary fission of actinides induced by polarized thermal neutrons. Also reported are the measured yields of prompt and delayed neutrons per fission event. The experimental data are analyzed within a novel theoretical framework developed by the JINR—RNC KI Collaboration, whereby the reduction of the multidimensional phase space of fission fragments to the JπK-channel space is consistently validated and the role of resonance interference in the observed correlation effects is revealed.

  8. An Investigation of Magneto-Optical Effects

    NASA Technical Reports Server (NTRS)

    Adams, Mitzi L.; Hagyard, Mona J.; West, Edward A.

    1998-01-01

    We exhibit the effects of Faraday rotation on the direction of the transverse component of the magnetic field in a simple, symmetric sunspot. A set of 35 polarization filtergrams of NOAA active region 4662 (June 9, 1985) were obtained with the Marshall Space Flight Center (MSFC) vector magnetograph. These filtergrams measured the Stokes I, Q, U, and V intensities averaged over the instrument's filter bandpass (0.0125 nm) for wavelengths from 0.017 nm in the red wing to 0.017 nm in the blue wing of the Lambda525.22 nm spectral line in steps of 0.001 nm. These data were used to derive the azimuth phi of the vector field as a function of wavelength over the field of view of the sunspot. We interpret the observed variations of this azimuth with wavelength as the effects of Faraday rotation and verify this interpretation by comparing these variations with those predicted from magneto-optical theory. In the theoretical calculations we use the line-profile parameters and magnetic field strength derived in previous work by Balasubramaniam and West (Astrophys. J 382, p. 699, 1991).

  9. Hematite at Meridiani Planum and Gusev Crater as identified by the Moessbauer Spectrometer MIMOS II

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Morris, R. V.; Rodionov, D.; Schroeder, C.; de Souza, P. A.; Yen, A.; Renz, F.; Wdowiak, T.

    2006-01-01

    The Moessbauer (MB) spectrometers on the MER rovers Opportunity and Spirit, which landed on Mars in January 2004, have identified the iron-containing mineral hematite (a-Fe2O3) at both landing sites. On Earth, hematite can occur either by itself or with other iron oxides as massive deposits, in veins , and as particles dispersed through a silicate or other matrix material. Hematite particle size can range from nanophase (superparamagnetic) to multidomain and particle shape ranges from equant to acicular to platy. Fine-grained hematite is red in color and is a pigmenting agent. Coarse-grained hematite can be spectrally neutral (gray) at visible wavelengths. Substitutional impurities, particularly Al, are common in hematite. Chemically pure, coarse-grained, and well-crystalline hematite has a magnetic transition (the Morin transition) at 260 K. Moessbauer spectra, recorded as a function of temperature, provide a way to characterize Martian hematite with respect to some of the physical and chemical characteristics. At Meridiani Planum besides the iron-sulfate mineral jarosite also the Fe-oxide hematite has been identified by the Moessbauer spectrometer, mainly in three distinct types of reservoir: - outcrop matrix material dominated by the mineral jarosite in the MB spectrum, certain basaltic soils, and mm-sized spherules dubbed blueberries. Moessbauer spectra of each reservoir yield a distinct set of hyperfine parameters for hematite, suggesting different degrees of crystallinity and particle size. The hematite found by MB instrument MIMOS II in the outcrop material shows the Morin transition at relatively high temperatures (ca. 250 K) which is an indication of pure and well-crystallized hematite. The source of the hematite in the Blueberries as identified by Moessbauer spectroscopy, and also by MiniTES, is not known. These spherules, covering nearly the whole landing site area (Eagle crater, plains, Endurance crater), may be concretions formed in the outcrop

  10. Investigations of initiation spot size effects

    SciTech Connect

    Clarke, Steven A; Akinci, Adrian A; Leichty, Gary; Schaffer, Timothy; Murphy, Michael J; Munger, Alan; Thomas, Keith A

    2010-01-01

    As explosive components become smaller, a greater understanding of the effect of initiation spot size on detonation becomes increasingly critical. A series of tests of the effect of initiation spot size will be described. A series of DOI (direct optical initiation) detonators with initiation spots sizes from {approx}50 um to 1000um have been tested to determine laser parameters for threshold firing of low density PETN pressings. Results will be compared with theoretical predictions. Outputs of the initiation source (DOI ablation) have been characterized by a suite of diagnostics including PDV and schlieren imaging. Outputs of complete detonators have been characterized using PDV, streak, and/or schlieren imaging. At present, we have not found the expected change in the threshold energy to spot size relationship for DOI type detonators found in similar earlier for projectiles, slappers and EBWs. New detonators designs (Type C) are currently being tested that will allow the determination of the threshold for spot sizes from 250 um to 105um, where we hope to see change in the threshold vs. spot size relationship. Also, one test of an extremely small diameter spot size (50um) has resulted in preliminary NoGo only results even at energy densities as much as 8 times the energy density of the threshold results presented here. This gives preliminary evidence that 50um spot may be beyond the critical initiation diameter. The constant threshold energy to spot size relationship in the data to date does however still give some insight into the initiation mechanism of DOI detonators. If the DOI initiation mechanism were a 1D mechanism similar to a slapper or a flyer impact, the expected inflection point in the graph would have been between 300um and 500um diameter spot size, within the range of the data presented here. The lack of that inflection point indicates that the DOI initiation mechanism is more likely a 2D mechanism similar to a sphere or rod projectile. We expect to

  11. Individual neurophysiological profile in external effects investigation

    NASA Astrophysics Data System (ADS)

    Schastlivtseva, Daria; Tatiana Kotrovskaya, D..

    Cortex biopotentials are the significant elements in human psychophysiological individuality. Considered that cortical biopotentials are diverse and individually stable, therefore there is the existence of certain dependence between the basic properties of higher nervous activity and cerebral bioelectric activity. The main purpose of the study was to reveal the individual neurophysiological profile and CNS initial functional state manifestation in human electroencephalogram (EEG) under effect of inert gases (argon, xenon, helium), hypoxia, pressure changes (0.02 and 0.2 MPa). We obtained 5-minute eyes closed background EEG on 19 scalp positions using Ag/AgCl electrodes mounted in an electrode cap. All EEG signals were re-referenced to average earlobes; Fast Furies Transformation analysis was used to calculate the relative power spectrum of delta-, theta-, alpha- and beta frequency band in artifact-free EEG. The study involved 26 healthy men who provided written informed consent, aged 20 to 35 years. Data obtained depend as individual EEG type and initial central nervous functional state as intensity, duration and mix of factors. Pronounced alpha rhythm in the raw EEG correlated with their adaptive capacity under studied factor exposure. Representation change and zonal distribution perversion of EEG alpha rhythm were accompanied by emotional instability, increased anxiety and difficulty adapting subjects. High power factor or combination factor with psychological and emotional or physical exertion minimizes individual EEG pattern.

  12. An investigation of the Venetian blind effect.

    PubMed

    Filley, E T; Khutoryansky, Natalie; Dobias, J J; Stine, Wm Wren

    2011-01-01

    When a rectangular wave grating is binocularly viewed with a neutral density filter over one eye, an illusory rotation resembling that of a partially opened Venetian blind is perceived (Cibis and Haber, 1951). Using a binary classification task, in the first experiment, the probability of perceiving a rotation in a given direction was measured as a function of a factorial combination of inter-ocular contrast (see Note 1) and luminance ratios. The probability of a rotation in a given direction decreased monotonically with the luminance of the brighter bars when the grating contains a less than unity contrast. This result is inconsistent with (i) the model of the Venetian blind effect proposed by Cibis and Haber (1951), (ii) a mechanism based on irradiation with a compressive non-linearity (von Helmholtz, 1911/1924, pp. 186-193) and (iii) contemporary stereo-energy/cross-correlation models of stereopsis. In the second and third experiments, we tested the prediction that irradiation combined with an early compressive non-linearity in response implies a positive relationship between both the threshold contrast or average luminance disparity to perceive rotation and the magnitude of perceived rotation, and the blur width at the bar's edge. No support was found for the prediction. We propose an intensity difference model of the probability of perceiving a rotation in a given direction as a function of the interocular difference in luminance or contrast. PMID:21864465

  13. 57Fe-labeled octamethylferrocenium tetrafluoroborate. X-ray crystal structures of conformational isomers, hyperfine interactions, and spin-lattice relaxation by Moessbauer spectroscopy.

    PubMed

    Schottenberger, Herwig; Wurst, Klaus; Griesser, Ulrich J; Jetti, Ram K R; Laus, Gerhard; Herber, Rolfe H; Nowik, Israel

    2005-05-11

    X-ray structure determinations of two different single crystals of octamethylferrocenium tetrafluoroborate (OMFc(+)BF(4)(-)) revealed conformational polymorphism with ligand twist angles of 180 degrees and 108 degrees , respectively. Their concomitant occurrence could be explained by the small lattice energy difference of 3.2 kJ mol(-1). Temperature-dependent Moessbauer spectroscopy of (57)Fe-labeled OMFc(+)BF(4)(-) over the range 90 < T < 370 K did not show the anomalous sudden increase in the motion of the metal atom as observed in neutral OMFc. Broadened absorption curves characteristic of relaxation spectra were obtained with an isomer shift of 0.466(6) mm s(-1) at 90 K. The temperature dependence of the isomer shift corresponded to an effective vibrating mass of 79 +/- 10 Da and, in conjunction with the temperature dependence of the recoil-free fraction, to a Moessbauer lattice temperature of 89 K. The spin relaxation rate could be better described by an Orbach rather than a Raman process. At 400 K, a reversible solid-solid transition to a plastic crystalline mesophase was noted. PMID:15869302

  14. Structural properties of magnetite under high pressure studied by Moessbauer spectroscopy

    SciTech Connect

    Kobayashi, Hisao; Isogai, Ichiro; Kamimura, Takashi; Hamada, Noriaki; Onodera, Hideya; Todo, Sakae; Mori, Nobuo

    2006-03-01

    We have measured the Moessbauer spectra of magnetite (Fe{sub 3}O{sub 4}) under a pressure of up to 18 GPa at room temperature using nonenriched high-quality samples. An analysis of the observed Moessbauer spectra confirms that Fe{sub 3}O{sub 4} does not undergo a magnetic or crystalline structural transition up to 18 GPa at room temperature. In the pressure dependences of the refined hyperfine interaction parameters, however, small but distinct anomalies are found at 7.0 GPa in the center shifts of two crystallographically nonequivalent Fe sites, which are caused by the discontinuous decrease of an oxygen internal coordinate in the cubic inverse spinel structure. We believe that the pressure-induced discontinuous change of the Fe-O bond length is related to the absence of a metal-insulator transition above 7.5 GPa.

  15. Moessbauer studies on LaNi(4.7)Sn(0.3) and its hydride

    NASA Technical Reports Server (NTRS)

    Oliver, F. W.; Morgan, W.; Hammond, E. C.; Wood, S.; May, L.

    1985-01-01

    Moessbauer measurements were made on LaNi(4.7)Sn(0.3) at room and liquid nitrogen temperatures. Experimental data yielded a singlet at room temperature and a doublet at liquid-nitrogen temperature. Spectra of the hydrided sample yielded a doublet at liquid-nitrogen temperature with an increase in the quadrupole splitting compared to the unhydrided spectra, but no change in the isomer shift. These data indicate that there is no significant interaction between the tin and the hydrogen. The magnetic character remained the same down to liquid-nitrogen temperature as evidenced by the Moessbauer data. X-ray diffraction measurements on the hydride showed an expanded lattice with the same structure as found for the unhydrided sample. A decrease in particle size was observed upon hydriding.

  16. A hydrogen bond study in tobacco mosaic virus using Moessbauer spectroscopy.

    PubMed

    Haffner, H; Appel, H; Holmes, K C

    1986-01-01

    The Moessbauer method was applied to obtain information on a suggested hydrogen bond in tobacco mosaic virus (TMV), between the hydroxyl group of Tyr 139 and a carboxyl oxygen of Glu 22 in a neighbouring subunit. Spectra of 129I were taken of 3,5-di-iodo-L-tyrosine as a free amino acid and in situ in TMV. The increase of the pK value of 3,5-di-iodo-L-tyrosine by 0.8 units at position 139 in TMV compared to the free value is a strong argument in favour of the existence of a hydrogen bond via the relevant hydroxyl group. The reported study demonstrates the surprising sensitivity of the observable Moessbauer parameters to details of the electronic configuration in the neighbourhood of the probe nucleus. PMID:3816698

  17. Moessbauer analysis of heat affected zones of an SA 508 steel weld

    SciTech Connect

    Kwon, S.J.; Oh, S.J.; Kim, S.; Lee, S.; Kim, J.H.

    1998-12-18

    Microstructure of a heat affected zone (HAZ) in a weld is influenced by many factors such as chemical composition, welding condition, and peak temperature. It is more complex under multi-pass welding because of the repeated heat input. For the analysis of the HAZ microstructure, optical microscope, electron microscope, and X-ray diffraction techniques have been widely used. However, their application is limited since they can hardly make quantitative analysis of HAZ where numerous phases such as martensite, bainite, ferrite, pearlite, austenite, and carbides are co-existing. Moessbauer spectroscopy, in such a case, is particularly useful due to the capability of quantitative analysis on the fraction of each phase. In this study, phases present in the HAZ of an SA 508 steel were identified, and their fractions were quantitatively determined by Moessbauer spectroscopy in conjunction with microscopic observations.

  18. Bulk and thin films of FeTe: A Moessbauer study

    NASA Technical Reports Server (NTRS)

    Escue, W. T.; Aggarwal, K.; Mendiratta, R. G.

    1977-01-01

    Studies of bulk and thin films of FeTe using Moessbauer spectroscopy showed that FeTe has one noncubic Fe (+2) site which is 3d2 4s 4p3 hybridized. The presence of dangling bands was indicated in spectra of FeTe thin films. The films showed a tendency of texture formation. The substrate was observed to influence the film structure and nature of bonds in films.

  19. Surface analysis of mixed-conducting ferrite membranes by the conversion-electron Moessbauer spectroscopy

    SciTech Connect

    Waerenborgh, J.C.; Tsipis, E.V.; Yaremchenko, A.A.; Kharton, V.V.

    2011-09-15

    Conversion-electron Moessbauer spectroscopy analysis of iron surface states in the dense ceramic membranes made of {sup 57}Fe-enriched SrFe{sub 0.7}Al{sub 0.3}O{sub 3-{delta}} perovskite, shows no traces of reductive decomposition or carbide formation in the interfacial layers after operation under air/CH{sub 4} gradient at 1173 K, within the limits of experimental uncertainty. The predominant trivalent state of iron cations at the membrane permeate-side surface exposed to flowing dry methane provides evidence of the kinetic stabilization mechanism, which is only possible due to slow oxygen-exchange kinetics and enables long-term operation of the ferrite-based ceramic reactors for natural gas conversion. At the membrane feed-side surface exposed to air, the fractions of Fe{sup 4+} and Fe{sup 3+} are close to those in the powder equilibrated at atmospheric oxygen pressure, suggesting that the exchange limitations to oxygen transport are essentially localized at the partially reduced surface. - Graphical Abstract: Conversion-electron Moessbauer spectroscopy analysis of dense ceramic membranes made of {sup 57}Fe-enriched SrFe{sub 0.7}Al{sub 0.3}O{sub 3-{delta}} perovskite, shows no reductive decomposition in thin interfacial layers after testing under air/CH{sub 4} gradient, enabling stable operation of the ferrite-based ceramic reactors for partial oxidation of methane. Highlights: > Conversion-electron Moessbauer spectroscopy is used for mixed-conducting membranes. > No decomposition is detected in the membrane surface layers under air/CH{sub 4} gradient. > Due to kinetic stabilization, Fe{sup 3+} states prevail at the surface exposed to methane. > Transmission Moessbauer spectra show perovskite decomposition on equlibration in CH{sub 4}. > Ferrite-based ceramic reactors can stably operate under air/CH{sub 4} gradient.

  20. Moessbauer spectroscopy studies of carbon-encapsulated magnetic nanoparticles obtained by different routes

    SciTech Connect

    Bystrzejewski, M.; Huczko, A.; Lange, H.; Grabias, A.; Borysiuk, J.

    2008-09-01

    Carbon-encapsulated magnetic nanoparticles (CEMNPs) are nanomaterials with a core-shell structure. Their intrinsic properties result both from the unique nature of the encapsulated magnetic phases and the high chemical stability of the external carbon shells. CEMNPs may find many prospective applications, e.g., in magnetic data storage, catalysis, xerography, magnetic resonance imaging, and in biomedical applications. Herein, we present detailed structural studies of such nanostructures by Moessbauer spectroscopy, x-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy. CEMNPs have been obtained by three different techniques: carbon arc, combustion synthesis, and radio frequency thermal plasma. The evaluation of the phase composition of the products was strongly limited due to the broadening and overlapping of the lines in XRD diffraction patterns. The presence of the semicrystalline phases, which could not been identified by XRD, was established by Moessbauer spectroscopy. Furthermore, the magnetic core phase composition was evaluated quantitatively. The products were purified before structural analyses to remove the nonencapsulated particles. The purification caused significant changes in the mass and the saturation magnetization. The Moessbauer spectra of the purified products were compared with the literature data concerning the as-produced CEMNPs.

  1. Moessbauer effect and X-ray distribution function analysis in complex Na{sub 2}O-CaO-ZnO-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glasses and glass-ceramics

    SciTech Connect

    Romero, M.; Rincon, J.M.; Musik, S.; Kozhukharov, V.

    1999-05-01

    Moessbauer spectroscopy at room temperature was carried out to determine the state of iron ions in complex glasses and glass-ceramics in the SiO{sub 2}-CaO-ZnO-Na{sub 2}O-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system. Isomer shift values of the glasses suggest that Fe{sup 3+} and Fe{sup 2+} are in tetrahedral and octahedral coordination, respectively. The spectrum of the glass-ceramic shows that about 60 wt% total iron is in the magnetite phase. The Fe{sup +3}/Fe{sup +2} ratio varies with the total iron oxide content of the glasses, indicating that the vitreous network is more distorted when the iron content is greater. X-ray diffraction measurements were carried out to obtain the radial distribution function (RDF). The interatomic distances for Si-Si and Si-O have been determined. The complex composition of these glasses does not allow the estimation of Al-O and Fe-O distances.

  2. The effect of amorphization on the local structure of arsenic chalcogenides

    SciTech Connect

    Bordovsky, G. A.; Marchenko, A. V.; Seregin, P. P. Terukov, E. I.

    2009-01-15

    The effect of amorphization on the symmetry of the local environment of chalcogen atoms in As{sub 2}S{sub 3}, As{sub 2}Se{sub 3}, and As{sub 2}Te{sub 3} compounds has been investigated by {sup 129}Te({sup 129}I) Moessbauer spectroscopy. Three states of triply coordinated tellurium atoms are indistinguishable in the Moessbauer spectra of crystalline As{sub 2}Te{sub 3}. Amorphization of As{sub 2}Te{sub 3} decreases the local symmetry of triply coordinated states of Te atoms and leads to the formation of doubly coordinated states in -As-Te-Te-As- chains. In the structure of crystalline As{sub 2}S{sub 3} and As{sub 2}Se{sub 3}, two states of doubly coordinated chalcogen atoms X in -As-X-As- chains manifest themselves in the broadening of the Moessbauer spectra. Amorphization of As{sub 2}S{sub 3} and As{sub 2}Se{sub 3} is not accompanied by a change in the local symmetry of doubly coordinated chalcogen atoms in -As-X-As- chains; however, doubly coordinated states of S and Se atoms in -As-X-X-As chains are formed in the amorphous material.

  3. Moessbauer study of iron-carbide growth and Fischer-Tropsch activity

    SciTech Connect

    Rao, K.R.P.M.; Huggins, F.E.; Huffman, G.P.

    1995-12-31

    There is a need to establish a correlation between the Fischer-Tropsch (FT) activity of an iron-based catalyst and the catalyst phase during FT synthesis. The nature of iron phases formed during activation and FT synthesis is influenced by the nature of the gas and pressure apart from other parameters like temperature, flow rate etc., used for activation. Moessbauer investigations of iron-based catalysts subjected to pretreatment at two different pressures in gas atmospheres containing mixtures of CO, H{sub 2}, and He have been carried out. Studies on UCI 1185-57 (64%Fe{sub 2}O{sub 3}/5%CuO/1%K{sub 2}O/30% Kaolin) catalyst indicate that activation of the catalyst in CO at 12 atms. leads to the formation of 100% magnetite and the magnetite formed gets rapidly converted to at least 90% of {chi}-Fe{sub 5}C{sub 2} during activation. The FT activity was found to be good at 70-80% of (H{sub 2}+CO) conversion. On the other hand, activation. The FT activity was found to be good at 70-80% of (H{sub 2}+CO) conversion. On the other hand, activation of the catalyst in synthesis gas at 12 atms. leads to formation of Fe{sub 3}O{sub 4} and it gets sluggishly converted to {chi}-Fe{sub 5}C{sub 2} and {epsilon}-Fe{sub 2.2}C during activation and both continue to grow slowly during FT synthesis. FT activity is found to be poor. Pretreatment of the catalyst, 100fe/3.6Si/0.71K at a low pressure of 1 atms. in syngas gave rise to the formation of {chi}-Fe{sub 5}C{sub 2} and good FT activity. On the other hand, pretreatment of the catalyst, 100Fe/3.6Si/0.71K at a relatively high pressure of 12 atms. in syngas did not give rise to the formation any carbide and FT activity was poor.

  4. Inelastic scattering in condensed matter with high intensity Moessbauer radiation. Final technical report, December 1, 1989--November 30, 1992

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1993-02-01

    The QUEGS facility at MURR has produced a number of new results and demonstrated the range of potential applications of high resolution, high intensity Moessbauer scattering. This work has been carried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and other systems, manuscripts submitted on alkali halides (Phys. Rev. B) and accurate Moessbauer lineshape measurements (Phys. Rev. C), and manuscripts in preparation on glycerol, NiAl and Moessbauer spectra obtained by modulating a scattering crystal. Recently, new collaborations have been initiated which will substantially enhance our efforts. These are with W. Steiner (Vienna), G. Coddens (Saclay), and R. D. Taylor (Los Alamos). Steiner is experienced with Fe-57 Moessbauer scattering, while Coddens specializes in quasielastic neutron scattering; both of these areas naturally complement our work. R. D. Taylor has pioneered Moessbauer spectroscopy from the time of its discovery and has already made important contributions to our study of lattice dynamics and superconductivity for lead alloyed with small quantities of tin. At the same time, a significant instrument upgrade is underway, funded in part by the DOE-URIP program.

  5. A Cost-Effective Model for Digital Forensic Investigations

    NASA Astrophysics Data System (ADS)

    Overill, Richard; Kwan, Michael; Chow, Kam-Pui; Lai, Pierre; Law, Frank

    Because of the way computers operate, every discrete event potentially leaves a digital trace. These digital traces must be retrieved during a digital forensic investigation to prove or refute an alleged crime. Given resource constraints, it is not always feasible (or necessary) for law enforcement to retrieve all the related digital traces and to conduct comprehensive investigations. This paper attempts to address the issue by proposing a model for conducting swift, practical and cost-effective digital forensic investigations.

  6. Coordination of Fe, Ga and Ge in high pressure glasses by Moessbauer, Raman and X-ray absorption spectroscopy, and geological implications

    NASA Technical Reports Server (NTRS)

    Fleet, M. E.; Henderson, G. S.; Herzberg, C. T.; Crozier, E. D.; Osborne, M. D.; Scarfe, C. M.

    1984-01-01

    For some time, it has been recognized that the structure of silicate liquids has a great bearing on such magma properties as viscosity, diffusivity, and thermal expansion and on the extrapolation of thermodynamic quantities outside of the experimentally measurable range. In this connection it is vital to know if pressure imposes changes in melt structure similar to the pressure-induced reconstructive transformations in crystals. In the present study on 1 bar and high pressure glasses, an investigation is conducted regarding the coordination of Fe(3+) in Fe silicate glasses by Moessbauer spectroscopy. Raman spectroscopy is employed to explore the coordinations of Ge(4+) in GeO2 glasses and of Ga(3+) in NaGa silicate glasses, while the coordination of Ga(3+) in NaGaSiO4 glasses is studied with the aid of methods of X-ray absorption spectroscopy.

  7. Pressure-induced phase transition of Fe{sub 2}TiO{sub 4}: X-ray diffraction and Moessbauer spectroscopy

    SciTech Connect

    Wu Ye; Wu Xiang; Qin Shan

    2012-01-15

    X-ray diffraction and Moessbauer spectroscopy were employed to investigate structural stability of Fe{sub 2}TiO{sub 4} under high pressure. Measurements were performed up to about 24 GPa at room temperature using diamond anvil cell. Experimental results demonstrate that Fe{sub 2}TiO{sub 4} undergoes a series of phase transitions from cubic (Fd3-bar m) to tetragonal (I4{sub 1}/amd) at 8.7 GPa, and then to orthorhombic structure (Cmcm) at 16.0 GPa. The high-pressure phase (Cmcm) of Fe{sub 2}TiO{sub 4} is kept on decompression to ambient pressure. In all polymorphs of Fe{sub 2}TiO{sub 4}, iron cations present a high-spin ferrous property without electric charge exchange with titanium cations at high pressure supported by Moessbauer evidences. - Graphical abstract: A series of phase transition of Fe{sub 2}TiO{sub 4} occurs from cubic (a) to tetragonal (b and c) then to orthorhombic phase (d-f) at high pressure. Highlights: Black-Right-Pointing-Pointer High pressure behaviors of Fe{sub 2}TiO{sub 4} were investigated. Black-Right-Pointing-Pointer Phase transitions were observed from cubic to tetragonal and then to orthorhombic. Black-Right-Pointing-Pointer Orthorhombic phase can be kept on decompression. Black-Right-Pointing-Pointer In all polymorphs of Fe{sub 2}TiO{sub 4}, iron ions are ferrous with high-spin state.

  8. Investigations of the Effective Diffusivity in the Oskarshamn Site Investigation Area

    NASA Astrophysics Data System (ADS)

    Lofgren, M.; Neretnieks, I.

    2004-12-01

    At present two sites in Sweden undergo site investigations for a deep geological repository for spent nuclear fuel. This paper present results concerning the effective diffusivity of the rock at repository depth in the Oskarshamn site investigation area. The geology of this site is dominated by granite, granodiorite and diorite. In a campaign, the effective diffusivity of the rock surrounding the 1000-meter deep boreholes KSH01A and KSH02 was investigated. The effective diffusivity is one of the most important parameters for radionuclide retention and strongly affects the performance of the geosphere as a natural barrier. The effective diffusivity was investigated in the laboratory on 83 samples, taken from the bore core of KSH01A and KSH02, by an electrical resistivity method. Formation factors ranging from 2.2 × 10-7 to 9.0 × 10-4 were obtained. The effective diffusivity was also investigated in-situ by formation factor logging using the electrical resistivity method. A total of 1867 in-situ formation factors were obtained that corresponded well with the formation factors obtained in the laboratory with a few exceptions. As such a great number of formation factors was obtained, formation factor distributions for specific rock types can be presented. The results suggest that the formation factor may be distributed according to the log-normal distribution. The results of this campaign show that the porosities and effective diffusivities used in the Swedish SR-97 safety assessment may have to be somewhat reassessed. The used of a single effective diffusivity value in a safety assessment could be questioned, as the obtained formation factors ranged over at least 3 orders of magnitude. In fact, at this site the traditional concept of the formation factor could be questioned, as the rock is very fractured and groundwater in fractions may greatly alter the storage capacity of the rock.

  9. Hematite at Meridiani Planum and Gusev Crater as identified by the Moessbauer Spectrometer MIMOS II

    NASA Astrophysics Data System (ADS)

    Klingelhoefer, G.; Morris, R. V.; Rodionov, D.; Schroeder, C.; de Souza, P. A.; Yen, A.; Renz, F.; Wdowiak, T.

    2004-12-01

    The Moessbauer (MB) spectrometers on the MER rovers Opportunity and Spirit, which landed on Mars in January 2004, have identified the iron-containing mineral hematite (a-Fe2O3) at both landing sites. On Earth, hematite can occur either by itself or with other iron oxides as massive deposits, in veins , and as particles dispersed through a silicate or other matrix material. Hematite particle size can range from nanophase (superparamagnetic) to multidomain and particle shape ranges from equant to acicular to platy. Fine-grained hematite is red in color and is a pigmenting agent. Coarse-grained hematite can be spectrally neutral (gray) at visible wavelengths. Substitutional impurities, particularly Al, are common in hematite. Chemically pure, coarse-grained, and well-crystalline hematite has a magnetic transition (the Morin transition) at ~260 K. Moessbauer spectra, recorded as a function of temperature, provide a way to characterize Martian hematite with respect to some of the physical and chemical characteristics. At Meridiani Planum besides the iron-sulfate mineral jarosite also the Fe-oxide hematite has been identified by the Moessbauer spectrometer, mainly in three distinct types of reservoir: - outcrop matrix material dominated by the mineral jarosite in the MB spectrum, certain basaltic soils, and mm-sized spherules dubbed blueberries. Moessbauer spectra of each reservoir yield a distinct set of hyperfine parameters for hematite, suggesting different degrees of crystallinity and particle size. The hematite found by MB instrument MIMOS II in the outcrop material shows the Morin transition at relatively high temperatures (ca. 250 K) which is an indication of pure and well-crystallized hematite. The source of the hematite in the `Blueberries' as identified by Moessbauer spectroscopy, and also by MiniTES, is not known. These spherules, covering nearly the whole landing site area (Eagle crater, plains, Endurance crater), may be concretions formed in the outcrop

  10. XRD and {sup 119}Sn Moessbauer spectroscopy characterization of SnSe obtained from a simple chemical route

    SciTech Connect

    Bernardes-Silva, Ana Claudia . E-mail: anaclaudiabs2000@yahoo.com.br; Mesquita, A.F.; Moura de Neto, E.; Porto, A.O. . E-mail: arilzaporto@yahoo.com.br; Ardisson, J.D.; Lameiras, F.S.

    2005-09-01

    Crystalline tin selenide semiconductor was synthesized by a chemical route. Selenium powder reacted with potassium boronhydride, giving a soluble selenium species potassium seleniumhydride. The reaction of potassium seleniumhydride with tin chloride produced crystalline tin selenide, which was characterized by X-ray diffraction, {sup 119}Sn Moessbauer spectroscopy and scanning electronic microscopy. The material was thermally treated, in nitrogen flow, at 300 and 600 deg. C for 2 h and the particle size evolution was studied by X-ray diffraction. The X-ray diffraction and {sup 119}Sn Moessbauer results showed that a mixture of tin oxides and orthorhombic tin selenide was obtained.

  11. Investigating Effects of Computer-Based Grammar Tutorials

    ERIC Educational Resources Information Center

    Kolesnikova, Anna

    2011-01-01

    This dissertation study examined a broad question of whether computer-based grammar tutorials are effective and welcome tools to review grammar for language learners by investigating effects of three different modes of such tutorials on learners' knowledge and satisfaction. For this study, I developed experimental tutorials in three different…

  12. The Miniaturized Moessbauer Spectrometers MIMOS II on MER: Four Years of Operation - A Summary

    NASA Technical Reports Server (NTRS)

    Fleischer, I.; Klingelhoefer, G.; Morris, R. V.; Rodionov, D.; Blumers, M.; Bernhardt, B.; Schroeder, C.; Ming, D. W.; Yen, A. S.; Cohen, B. A.; McCoy, T. J.; Mittlefehldt, D. W.; Schmidt, M. E.; Girones Lopez, J.; Studlek, G.; Brueckner, J.; Gellert, R.; d'Uston, C.

    2008-01-01

    The two Miniaturized Moessbauer Spectrometers (MIMOS II) on board the two Mars Exploration Rovers Spirit and Opportunity have now been collecting important scientific data for more than four years. The spectrometers provide information about Fe-bearing mineral phases and determine Fe oxidation states. The total amount of targets analized exceeds 600, the total integration time exceeds 260 days for both rovers. Since landing, more than five half-lives of the Co-57 MB sources have past (intensity at the time of landing approx. 150 mCi). Current integration times are about 50 hours in order to achieve reasonable statistics as opposed to 8 hours at the beginning of the mission. In total, 13 different mineral phases were detected: Olivine, pyroxene, hematite, magnetite and nanophase ferric oxide were detected at both landing sites. At Gusev, ilmenite, goethite, a ferric sulfate phase and a yet unassigned phase (in the rock Fuzzy Smith) were detected. At Meridiani, jarosite, metallic iron in meteoritic samples (kamacite), troilite, and an unassigned ferric phase were detected. Jarosite and goethite are of special interest, as these minerals are indicators for water activity. In this abstract, an overview of Moessbauer results will be given, with a focus on data obtained since the last martian winter. The MER mission has proven that Moessbauer spectroscopy is a valuable tool for the in situ exploration of extraterrestrial bodies and for the study of Febearing samples. The experience gained through the MER mission makes MIMOS II a obvious choice for future missions to Mars and other targets. Currently, MIMOS II is on the scientific payload of two approved future missions: Phobos Grunt (Russian Space Agency; 2009) and ExoMars (European Space Agency; 2013).

  13. Magnetic properties and Moessbauer analyses of glass from the K-T boundary, Beloc, Haiti

    NASA Technical Reports Server (NTRS)

    Senftle, F. E.; Thorpe, A. N.; May, L.; Barkatt, A.; Adel-Hadadi, M. A.; Marbury, G. S.; Izett, G.; Sigurdsson, H.; Maurasse, F. J.-M. R.

    1993-01-01

    The experimental magnetic susceptibility, the temperature-independent component of the magnetic susceptibility, the magnetization, and the Curie constant have been measured for a number of specimens of glass from the K-T boundary found at Beloc, Haiti, and the results are compared with those of similar measurements of tektites. Because the Fe(3+)/Fe(2+) ratio is needed to calculate the magnetic parameters, Moessbauer spectroscopic measurements were also made. The data were consistent with the classification of the Beloc glasses as tektites.

  14. Combined backscatter Moessbauer spectrometer/x ray fluorescence analyzer (BaMS/XRF) for extraterrestrial surfaces

    NASA Technical Reports Server (NTRS)

    Shelfer, T. D.; Wills, E. L.; Agresti, D. G.; Pimperl, M. M.; Shen, M. H.; Morris, R. V.; Nguyen, T.

    1993-01-01

    We have designed and tested a prototype combined backscatter Moessbauer spectrometer and x-ray fluorescence analyzer (BaMS/XRF). A space qualified instrument based on this design would be suitable for in-situ use on planetary missions to the surfaces of the Moon (Artemis and lunar outpost), Mars (MESUR), asteroids, or other solid solar system objects. The BaMS/XRF instrument is designed to be capable of concurrent sample analyses for the mineralogy of iron-bearing phases and elemental composition without the need for sample preparation.

  15. To the problem about the origin of lunar maria and continents (Moessbauer investigations)

    NASA Technical Reports Server (NTRS)

    Malysheva, T. V.

    1977-01-01

    A comparative study of Mossbauer spectra of regolith returned by the Luna 16 and Luna 20 spacecraft is presented. The Mossbauer spectra of the mare regolith differs significantly for all fractions from the spectra for the same fractions of continental regolith. The total quantity of iron is 1.85 times greater in the mare regolith. There is 2.4 times less olivine in the mare region than in the continental region. The pyroxene component of the mare regolith is less homogeneous in composition (contains more augite and glass) and is present in larger quantities. Ilmenite was found only in the mare regolith. In the continental region, the predominant titanium-containing phase is ulvospinel. The mare regolith contains more metallic iron, which is more finely dispersed and contains less nickel. Troilite is found in the maria region. Based on these differences, it is concluded that the formation of continental rocks occurred at an earlier stage of crystallization from the melt and at higher temperatures and higher partial pressures of oxygen. The mare basalts crystallized from a more reduced magma, apparently in a later process.

  16. Multilevel relaxation model for describing the Moessbauer spectra of nanoparticles in a magnetic field

    SciTech Connect

    Chuev, M. A.

    2012-04-15

    A theory is developed for the Moessbauer absorption spectra of an ensemble of single-domain particles in a magnetic field. This theory is based on the generalization of a relaxation model with a quantummechanical description of the stationary states of a particle and on the formalism of Liouville operators for describing the hyperfine interaction for a hyperfine field changing in both the magnitude and direction for various stationary states. The general scheme of calculating relaxation Moessbauer spectra in terms of a standard stochastic approach is substantially optimized using operations with block matrices and a unique tridiagonalization of high-rank non-Hermitian matrices with a simple nonorthogonal transformation in the calculation procedure. The resulting model can easily be implemented on a personal computer. It considers the physical mechanisms of formation of a hyperfine structure in a spectrum of nanoparticles in a real situation and self-consistently describes the qualitative features of the nontrivial evolution of spectra with the temperature and the magnetic-field direction and strength, which has been detected in {sup 57}Fe nucleus experiments performed on magnetic nanoparticles for half a century.

  17. Moessbauer spectra of olivine-rich achondrites - Evidence for preterrestrial redox reactions

    NASA Technical Reports Server (NTRS)

    Burns, R. G.; Martinez, S. L.

    1991-01-01

    Moessbauer spectral measurements at 4.2 K were made on several ureilites and the two shergottites found in Antarctica, as well as two ureilite falls, three SNC meteorite falls, and two finds in order to distinguish products of preterrestrial redox reactions from phases formed during oxidative weathering on the earth. The spectra indicated that several ureilites contain major proportions of metallic iron, much of which resulted from preterrestrial carbon-induced reduction of ferrous iron in the outermost 10-100 microns of olivine grains in contact with carbonaceous material in the ureilites. The cryptocrystalline nature of these Fe inclusions in olivine renders the metal extremely vulnerable to aerial oxidation, even in ureilites collected as falls. It is inferred that the nanophase ferric oxides or oxyhydroxides identified in Brachina and Lafayette were produced by terrestrial weather of olivines before the meteorites were found. The absence of goethite in two olivine-bearing Antarctic shergottites suggests that the 2 percent ferric iron determined in their Moessbauer spectra also originated from oxidation on Mars.

  18. An East to West Mineralogical Trend in Mars Exploration Rover Spirit Moessbauer Spectra of Home Plate

    NASA Technical Reports Server (NTRS)

    Schroder, C.; Di, K.; Morris, R. V.; Klingelhofer, G.; Li, R.

    2008-01-01

    Home Plate is a light-toned plateau approx.90 m in diameter within the Inner Basin of the Columbia Hills in Gusev crater on Mars. It is the most extensive exposure of layered bedrock encountered by Spirit to date, and it is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. Textural observations suggest an explosive origin and geochemical observations favor volcanism, probably a hydrovolcanic explosion [1]. Since it first arrived at Home Plate on sol 744, Spirit has circumnavigated the plateau (Fig. 1) and is now, since sol 1410, resting at its Winter Haven 3 location at the north end of Home Plate. Results: The MER Moessbauer spectrometers determine Fe oxidation states, identify Fe-bearing mineral phases and quantify the distribution of Fe among oxidation states and mineral phases [2]. Moessbauer spectra of Home Plate bedrock were obtained in five different locations from nine different targets (Fig. 1): Barnhill Ace, Posey Manager, and James Cool Papa Bell Stars at the northwest side of Home Plate; Pesapallo, June Emerson, and Elizabeth Emery on the east side; Texas Chili on the south side; Pecan Pie on the west side; and Chanute on the north side.

  19. Direct and Extended Vocabulary Instruction in Kindergarten: Investigating Transfer Effects

    ERIC Educational Resources Information Center

    Coyne, Michael D.; McCoach, D. Betsy; Loftus, Susan; Zipoli, Richard, Jr.; Ruby, Maureen; Crevecoeur, Yvel C.; Kapp, Sharon

    2010-01-01

    The purpose of this study was to investigate the efficacy of an 18-week program of direct and extended vocabulary instruction with kindergarten students on both proximal measures of target word knowledge and transfer measures of generalized language and literacy. A second purpose was to examine whether treatment effects would be moderated by…

  20. Second Language Comprehensibility Revisited: Investigating the Effects of Learner Background

    ERIC Educational Resources Information Center

    Crowther, Dustin; Trofimovich, Pavel; Saito, Kazuya; Isaacs, Talia

    2015-01-01

    The current study investigated first language (L1) effects on listener judgment of comprehensibility and accentedness in second language (L2) speech. The participants were 45 university-level adult speakers of English from three L1 backgrounds (Chinese, Hindi, Farsi), performing a picture narrative task. Ten native English listeners used…

  1. Investigating the Effectiveness of Computer Simulations for Chemistry Learning

    ERIC Educational Resources Information Center

    Plass, Jan L.; Milne, Catherine; Homer, Bruce D.; Schwartz, Ruth N.; Hayward, Elizabeth O.; Jordan, Trace; Verkuilen, Jay; Ng, Florrie; Wang, Yan; Barrientos, Juan

    2012-01-01

    Are well-designed computer simulations an effective tool to support student understanding of complex concepts in chemistry when integrated into high school science classrooms? We investigated scaling up the use of a sequence of simulations of kinetic molecular theory and associated topics of diffusion, gas laws, and phase change, which we designed…

  2. Effects of aleurone layer on rice cooking: A histological investigation.

    PubMed

    Wu, Jianyong; Chen, Jun; Liu, Wei; Liu, Chengmei; Zhong, Yejun; Luo, Dawen; Li, Zhongqiang; Guo, Xiaojuan

    2016-01-15

    Understanding how aleurone layer (AL) affects rice cooking behaviour is important for rice processing. Individual effects of AL on rice cooking behaviour were evaluated and histological characters of AL before and after cooking were investigated. AL slightly affected rice cooking quality (optimum cooking time, water absorption, volume expansion ratio and total solids loss) while remarkably affected rice texture (hardness and adhesiveness) and peak viscosity. Histological investigation showed that channels were formed in AL during cooking. The channels facilitated the penetration of water, which could explain why AL exhibited slight effects on rice cooking quality. In addition, thick cell walls and thermally stable aleurone grains were widely distributed in AL. Leached components accumulated on them and formed a reinforced coated film on rice surface during cooking, which may be a possible mechanism accounting for the remarkable effect of AL on rice texture. Histological characters of AL are closely related with rice cooking behaviour. PMID:26258698

  3. Investigation of Laser Peening Effects on Hydrogen Charged Stainless Steels

    SciTech Connect

    Zaleski, Tania M.

    2008-10-30

    Hydrogen-rich environments such as fuel cell reactors can exhibit damage caused by hydrogen permeation in the form of corrosion cracking by lowering tensile strength and decreasing material ductility. Coatings and liners have been investigated, but there were few shot-peening or laser peening studies referenced in the literature with respect to preventing hydrogen embrittlement. The surface compressive residual stress induced by laser peening had shown success in preventing stress corrosion cracking (SCC) for stainless steels in power plants. The question arose if the residual stresses induced by laser peening could delay the effects of hydrogen in a material. This study investigated the effect of laser peening on hydrogen penetration into metal alloys. Three areas were studied: laser peening, hydrogenation, and hydrogen detection. This study demonstrated that laser peening does not reduce the hydrogen permeation into a stainless steel surface nor does it prevent hydrogen embrittlement. The effect of laser peening to reduce hydrogen-assisted fatigue was unclear.

  4. Investigating the Icr Effect in a Zhadin's Cell.

    PubMed

    Giuliani, L; D'Emilia, E; Grimaldi, S; Lisi, A; Bobkova, N; Zhadin, M N

    2009-06-01

    Investigations into the ion cyclotronic resonance (ICR) in living matter confront the so called Zhadin effect (12), whose explanation is not fully achieved. Several attempts have been done to explain this phenomenon, the most interesting of which is based on Quantum Electrodynamics (18): the molecules of water, the ions and the biomolecules form extended mesoscopic regions, called Coherence Domains (CD), where they oscillate in unison between two selected levels of their spectra in tune with a self-produced coherent E.M. field having a well defined frequency, dynamically trapped within the CD. Moreover, it is possible, to induce, by an external applied field (either hydrodynamical or EM) or also by a chemical stimulation, coherent excitations of CD's that give rise to electric currents circulating without friction within the CD's: as a consequence magnetic fields are produced. A resonating magnetic field thus is able to extract the ions from the orbit and push them in the flowing current. Electrochemical investigation of the system suggested that the observed phenomenon involves the transitory activation of the anode due to ICR, followed by anode passivation due to the adsorption of amino acid and its oxidation products (18). This hypothesis induced us to investigate an alternate configuration of the experiment, removing the electrolytic cell and submitting a flask containing the solution into a condenser to be exposed to the proper ICR. Temperature and variable parameters involved in the effect have been investigated in order to overcome the randomness of the effect. PMID:23675133

  5. Investigation of fabrication and environmental effects on bioceramic bone scaffolds

    NASA Astrophysics Data System (ADS)

    Vivanco Morales, Juan Francisco

    2011-12-01

    Bioactive ceramic materials like tricalcium phosphates (TCP) have been emerging as viable material alternatives to the current therapies of bone scaffolding to target fracture healing and osteoporosis. Once scaffolds are implanted at the defect site they should provide mechanical and biological functions, ultimately serving to facilitate with surrounding native tissue. Optimal osteogenic signal expression and subsequent differentiation of cells seeded on the scaffold in both in vivo and in vitro conditions is known to be influenced by scaffold properties and biomechanical environmental conditions. Thus, the objective of this research was to investigate the effect of fabrication and environmental variables on the properties of bioceramic scaffolds for bone tissue engineering applications. Specifically, the effect of sintering temperature in the range of 950°C -1150°C of a cost-effective on a large scale manufacturing process, on the physical and mechanical properties of bioceramic bone scaffolds, was investigated. In addition, the effect of a controlled environment was investigated by implementing a bioreactor and bone loading system to study the response of ex vivo trabecular bone to compressive load while perfused with culture medium. Collectively, this thesis demonstrates that: (1) the sintering temperature to fabricate bioceramic scaffolds can be tuned to structural properties, and (2) the use of a controlled mechanical and biochemical environment can enhance bone tissue development. These findings support the development of clinically successful bioceramic scaffolds that may stimulate bone regeneration and scaffold integration while providing structural integrity.

  6. Coherent nuclear resonant scattering by {sup 61}Ni using the nuclear lighthouse effect

    SciTech Connect

    Roth, T.; Leupold, O.; Wille, H.-C.; Rueffer, R.; Quast, K.W.; Burkel, E.; Roehlsberger, R.

    2005-04-01

    We have observed coherent nuclear resonant scattering of synchrotron radiation from the 67.41-keV level of {sup 61}Ni. The time evolution of the forward scattering signal was recorded by employing the nuclear lighthouse effect. This method is used to investigate Moessbauer isotopes in a coherent scattering process with synchrotron radiation at high transition energies. The decay of the excited ensemble of nuclei in Ni metal shows quantum beats that allowed the determination of the magnetic hyperfine field at the {sup 61}Ni nucleus. Moreover, we determined the lifetime of the 67.41-keV level of {sup 61}Ni to be 7.4(1) ns.

  7. Investigation of the effects of cobalt ions on epoxy properties

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Stoakley, D. M.

    1986-01-01

    The effects of Co(acac)sub x complexes on MY-720 epoxy properties have been investigated. It appears that Co2(+) ions form antibonding or nonbonding orbitals which increase the free volume and also reduce the cohesiveness of the host epoxy. The effects of Co2(+) ions, on the other hand, seem to result in increased Cohesiveness of the epoxy. The experimental values of magnetic moments of both types of ions in MY-720 suggest that the orbital momentum contributions of the (3d) electrons are partially conserved, though the effect is more pronounced for Co2(+) ions. The coordination environment of the cobalt ions in the host epoxy does not appear to be uniquely defined. These results indicate that the effects of metal ions on resin properties cannot be easily predicted on the basis of ligand field theory argument alone. Complex interactions between metal ions and host epoxy molecular structure suggest the desirability of parallel experimental investigations of electronic, magnetic, and mechanical properties of metal ion-containing epoxy samples for comparison with theory.

  8. Effect of family medicine residents on use of diagnostic investigations

    PubMed Central

    Seong, Augene; Osmun, W.E.

    2014-01-01

    Abstract Objective To determine the effect of the presence of family medicine residents on the use of laboratory and imaging investigations in a rural emergency department (ED). Design A retrospective cross-sectional electronic chart audit was completed. Background characteristics, as well as type and number of ordered investigations, were compared between study groups. Setting Strathroy Middlesex General Hospital in Strathroy, Ont, a rural community hospital that sees approximately 20 000 ED visits per year. Participants A total of 2000 sequential ED visits, including adult and pediatric patients. The test group consisted of patients seen while a resident was present in the ED. The control group consisted of patients seen while no residents were present in the ED. Main outcome measures Twenty-two distinct categories of common ED investigations were studied. Results There was no statistically significant difference between study groups for 19 of the 22 categories of investigations. There were significant differences in 3 categories: an increased number of D-dimer assays for patients seen while there were no residents in the ED (1.7% of patients vs 0.5% of patients, P = .03) and increased computed tomography and ultrasound imaging for patients seen while a resident was in the ED (4.8% vs 1.8%, P = .0012, and 5.3% and 1.7%, P < .001, respectively). These differences are likely not owing to resident involvement but are explained by a difference in test availability between groups. Conclusion The study was underpowered for most categories of studied investigations. However, the trends demonstrated in this study suggest that the presence of family medicine residents in a rural community ED does not substantially affect the overall use of diagnostic investigations. PMID:25217692

  9. Moessbauer analysis of Lewisville, Texas, archaeological site lignite and hearth samples. Environmental geology notes

    SciTech Connect

    Shiley, R.H.; Hughes, R.E.; Cahill, R.A.; Konopka, K.L.; Hinckley, C.C.

    1985-01-01

    The Lewisville site, located in Denton County on the Trinity River north of Dallas, Texas, was thought to provide evidence of the earliest human activity in the western hemisphere. Radiocarbon dates of 37,000 to 38,000 B.P. determined for the site in the late 1950s conflicted with the presence of a Clovis point, which would fix the age of the site between 11,000 and 11,500 B.P. It was hypothesized (Johnson, 1982) that Clovis people were burning lignite from nearby outcrops: lignite in hearth residues would give older than actual ages by radiocarbon dating. X-ray diffraction and instrumental neutron-activation analysis proved inconclusive; however, Moessbauer spectroscopy indicated that hematite, a pyrite combustion product, was present in the ash. From this evidence the authors conclude that there is some support for the hypothesis.

  10. Fe-Bearing Phases Indentified by the Moessbauer Spectrometers on the Mars Exploration Rovers: An Overview

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Klingelhoefer, G.; Ming, D. W.; Schroeder, C.; Rodionov, D.; Yen, A.; Gellert, R.

    2006-01-01

    The twin Mars Exploration Rovers Spirit and Opportunity have explored the martian surface at Gusev Crater (GC) and Meridiani Planum (MP), respectively, for about two Earth years. The Moessbauer (MB) spectrometers on both rovers have analyzed an aggregate of approx.200 surface targets and have returned to Earth information on the oxidation state of iron, the mineralogical composition of Fe-bearing phases, and the distribution of Fe among oxidation states and phases at the two landing sites [1-7]. To date, 15 component subspectra (10 doublets and 5 sextets) have been identified and most have been assigned to mineralogical compositions. Two subspectra are assigned to phases (jarosite and goethite) that are marker minerals for aqueous processes because they contain hydroxide anion in their structures. In this paper, we give an overview of the Febearing phases identified and their distributions at Gusev crater and Meridiani Planum.

  11. Fe-Bearing Phases Identified by the Moessbauer Spectrometers on the Mars Exploration Rovers: An Overview

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Klingelhoefer, G.; Rodionov, D.; Yen, A.; Gellert, R.

    2006-01-01

    The twin Mars Exploration Rovers Spirit and Opportunity have explored the martian surface at Gusev Crater (GC) and Meridiani Planum (MP), respectively, for about two Earth years. The Moessbauer (MB) spectrometers on both rovers have analyzed an aggregate of 200 surface targets and have returned to Earth information on the oxidation state of iron, the mineralogical composition of Febearing phases, and the distribution of Fe among oxidation states and phases at the two landing sites [1-7]. To date, 15 component subspectra (10 doublets and 5 sextets) have been identified and most have been assigned to mineralogical compositions. Two subspectra are assigned to phases (jarosite and goethite) that are marker minerals for aqueous processes because they contain hydroxide anion in their structures. In this paper, we give an overview of the Febearing phases identified and their distributions at Gusev crater and Meridiani Planum.

  12. A second international cooperative investigation into thioacetazone side effects

    PubMed Central

    Miller, A. B.; Nunn, A. J.; Robinson, D. K.; Fox, Wallace; Somasundaram, P. R.; Tall, Ruth

    1972-01-01

    As part of a large-scale international cooperative investigation into the side effects of thioacetazone-containing regimens in the treatment of tuberculosis, an evaluation has been made of the variation in the frequency of side effects between different countries and between different centres in the same country and of the likely reasons for this variation. In 3 countries patients of different racial origin were under observation in the same hospital. Over a 12-week period of treatment there was considerable variation between the countries and centres in the overall frequency of side effects and of those leading to a major departure from prescribed treatment, the variation being similar for the two thioacetazone-containing regimens and for the streptomycin plus isoniazid control regimen, though at a lower level for the latter. In Malaysia, Singapore, and Trinidad, where different racial groups were under treatment, there was no clear indication that race was an important factor in explaining the differences between countries, except for cutaneous side effects in Trinidad and possibly in Malaysia. It is concluded that the differences in the frequency of side effects to thioacetazone-containing regimens probably result from variation in the closeness of supervision of patients, in the recording and interpretation of side effects, and in environmental factors including the previous use of other medicaments or exposure to sensitizing substances. PMID:4118761

  13. Mineralogy at Gusev Crater and Meridiani Planum from the Moessbauer Spectrometers on the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Klingelhoefer, Goestar

    2006-01-01

    The Moessbauer spectrometers on the twin MER rovers Spirit and Opportunity have provided significant new information on the distribution of iron among its oxidation states, the identification of the mineralogical composition of iron-bearing phases, and the distribution of iron among those phases for rock and soil at Gusev Crater and Meridiani Planum. The plains of Gusev Crater are dominated by olivine-bearing basalt (approximately Fo(60)) and Fe(3+)/Fe(total)=0.1 - 0.5. The oxide mineral generally present is magnetite. In contrast, initial results for the Columbia Hills are consistent with the presence of hematite and a ferrous iron phase, possibly pyroxene. Gusev spectra also have a ferric doublet (not jarosite) that is tentatively associated with nano-phase ferric oxide. A wider diversity of material is present at Meridiani Planum. Significantly, jarosite-bearing outcrop is present throughout the region, with good exposures in impact craters such as Eagle and Endurance (Fe(3+)/Fe (total) approx. 0.9). The Moessbauer identification of jarosite (a hydroxyl-bearing sulfate mineral) is evidence for aqueous, acid-sulfate processes on Mars. Hematite is observed within the outcrop matrix and in the spheroidal particles (Blueberries) found within the outcrop and as a surface lag. An isolated rock (Bounce Rock) was the only sample at either landing site whose iron-bearing phase was dominated by pyroxene. The basaltic sand in the central portion of Eagle crater, in the intercrater plains, and between slabs of outcrop at both Eagle and Endurance craters is olivine-bearing basalt. The widespread occurrence of olivine-bearing basalt at both MER landing sites implies that physical, rather than chemical, weathering processes dominate at the surface of contemporary Mars.

  14. Moessbauer studies of pressure-induced amorphization in the molecular crystal SnBr{sub 4}

    SciTech Connect

    Hearne, G.R.; Pasternak, M.P. |; Taylor, R.D.

    1995-10-01

    A single line spectrum is characteristic of the Moessbauer data obtained in the 0--5 GPa range, indicating the preservation of fourfold symmetry of the SnBr{sub 4} molecule in the crystal. Above 5 GPa, near {ital P}{sub {ital c}}, a {ital quadruple} {ital interaction} takes place concurrent with a dramatic increase in the {ital recoil{minus}free} {ital fraction} $({ital f})---. The value of the quadrupole splitting reaches a maximum of 0.9 mm/s at {ital P}{similar_to}15 GPa and remains constant thereafter. By {similar_to}9 GPa the absorption area, which is proportional to {ital f}, increases by 30--40 % over the lowest pressure value and then remains constant at higher pressure. These results are consistent with the formation of a molecular species, e.g., a (SnBr{sub 4}){sub 2} dimer, lacking the {ital T}{sub {ital d}} symmetry at the original Sn{sup 4+} site and having optical phonons {ital hard} enough not to be excited by the nuclear recoil process. Molecular association into (SnBr{sub 4}){sub 2} dimers, the building block of the high-pressure disordered state, also explains many of the experimental features of the Raman data. Upon decompression, Moessbauer (and Raman) data suggest that these dimers dissociate into monomers at {similar_to}5 GPa; however, a disordered structure of SnBr{sub 4} persists as pressure is decreased further. Crystallization is fully recovered below 1 GPa. The nature of the pressure-induced amorphization of the insulator SnBr{sub 4} is discussed in terms of the structural and valence properties of the analogous metallic SnI{sub 4}.

  15. Towards More Secure Biometric Readers for Effective Digital Forensic Investigation

    NASA Astrophysics Data System (ADS)

    Trabelsi, Zouheir; Al-Hemairy, Mohamed; Baggili, Ibrahim; Amin, Saad

    This paper investigates the effect of common network attacks on the performance, and security of several biometric readers. Experiments are conducted using Denial of Service attacks (DoSs) and the ARP cache poisoning attack. The experiments show that the tested biometric readers are vulnerable to DoS attacks, and their recognition performance is significantly affected after launching the attacks. However, the experiments show that the tested biometric readers are secure from the ARP cache poisoning attack. This work demonstrates that biometric readers are easy targets for malicious network users, lack basic security mechanisms, and are vulnerable to common attacks. The confidentiality, and integrity of the log files in the biometric readers, could be compromised with such attacks. It then becomes important to study these attacks in order to find flags that could aid in a network forensic investigation of a biometric device.

  16. Experimental Investigation of a Wing-in-Ground Effect Craft

    PubMed Central

    Tofa, M. Mobassher; Ahmed, Yasser M.; Jamei, Saeed; Priyanto, Agoes; Rahimuddin

    2014-01-01

    The aerodynamic characteristics of the wing-in-ground effect (WIG) craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM) wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future. PMID:24701170

  17. Design and Construction of an Autonomous Low-Cost Pulse Height Analyzer and a Single Channel Analyzer for Moessbauer Spectroscopy

    SciTech Connect

    Velasquez, A.A.; Trujillo, J.M.; Morales, A.L.; Tobon, J.E.; Gancedo, J.R.; Reyes, L.

    2005-04-26

    A multichannel analyzer (MCA) and a single channel-analyzer (SCA) for Moessbauer spectrometry application have been designed and built. Both systems include low-cost digital and analog components. A microcontroller manages, either in PHA or MCS mode, the data acquisition, data storage and setting of the pulse discriminator limits. The user can monitor the system from an external PC through the serial port with the RS232 communication protocol. A graphic interface made with the LabVIEW software allows the user to adjust digitally the lower and upper limits of the pulse discriminator, and to visualize as well as save the PHA spectra in a file. The system has been tested using a 57Co radioactive source and several iron compounds, yielding satisfactory results. The low cost of its design, construction and maintenance make this equipment an attractive choice when assembling a Moessbauer spectrometer.

  18. Identification of Iron-Bearing Phases on the Martian Surface and in Martian Meteorites and Analogue Samples by Moessbauer Spectroscopy

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Agresti, D. G.; Schroeder, C.; Rodionov, D.; Yen, A.; Ming, Doug; Morris, Richard V.

    2007-01-01

    The Moessbauer spectrometers on the Mars Exploration Rovers (MER) Spirit (Gusev Crater) and Opportunity (Meridiani Planum) have each analyzed more than 100 targets during their ongoing missions (>1050 sols). Here we summarize the Fe-bearing phases identified to date and compare the results to Moessbauer analyses of martian meteorites and lunar samples. We use lunar samples as martian analogues because some, particularly the low-Ti Apollo 15 mare basalts, have bulk chemical compositions that are comparable to basaltic martian meteorites [1,2]. The lunar samples also provide a way to study pigeonite-rich samples. Pigeonite is a pyroxene that is not common in terrestrial basalts, but does often occur on the Moon and is present in basaltic martian meteorites

  19. Investigating on the Methodology Effect When Evaluating Lucid Dream.

    PubMed

    Ribeiro, Nicolas; Gounden, Yannick; Quaglino, Véronique

    2016-01-01

    Lucid dreaming (LD) is a state of consciousness in which the dreamer is aware that he or she is dreaming and can possibly control the content of his or her dream. To investigate the LD prevalence among different samples, researchers have used different types of methodologies. With regard to retrospective self-report questionnaire, two ways of proceeding seem to emerge. In one case, a definition of LD is given to participants ("During LD, one is-while dreaming-aware of the fact that one is dreaming. It is possible to deliberately wake up, to control the dream action, or to observe passively the course of the dream with this awareness"), while in the other instances, participants are presented separate questions targeting specific LD indicators (dream awareness and dream control). In the present study, we measured LD frequency in a sample of French student in order to investigate for possible disparities in LD frequency depending on the type of questionnaire as outlined above. Moreover, we also study links between the prevalence of LD as assessed, respectively, by each questionnaire with various factors such as Vividness of Mental Imagery and Parasomnia. Results revealed no significant difference between LD frequencies across questionnaires. For the questionnaire with definition (DefQuest), 81.05% of participants reported experience of LD once or more. Concerning the questionnaire based on LD indicators (AwarContQuest), 73.38% of participants reported having experienced LD once or more. However, with regard to the correlations analysis, links between LD prevalence and factors such as Vividness of Mental Imagery and Parasomnia, varied across questionnaires. This result is an argument suggesting that researchers should be careful when investigating links between LD and other factors. The type of methodology may influence findings on LD research. Further studies are needed to investigate on the methodology effect in LD research namely on the respective weight of

  20. Investigating on the Methodology Effect When Evaluating Lucid Dream

    PubMed Central

    Ribeiro, Nicolas; Gounden, Yannick; Quaglino, Véronique

    2016-01-01

    Lucid dreaming (LD) is a state of consciousness in which the dreamer is aware that he or she is dreaming and can possibly control the content of his or her dream. To investigate the LD prevalence among different samples, researchers have used different types of methodologies. With regard to retrospective self-report questionnaire, two ways of proceeding seem to emerge. In one case, a definition of LD is given to participants (“During LD, one is–while dreaming–aware of the fact that one is dreaming. It is possible to deliberately wake up, to control the dream action, or to observe passively the course of the dream with this awareness”), while in the other instances, participants are presented separate questions targeting specific LD indicators (dream awareness and dream control). In the present study, we measured LD frequency in a sample of French student in order to investigate for possible disparities in LD frequency depending on the type of questionnaire as outlined above. Moreover, we also study links between the prevalence of LD as assessed, respectively, by each questionnaire with various factors such as Vividness of Mental Imagery and Parasomnia. Results revealed no significant difference between LD frequencies across questionnaires. For the questionnaire with definition (DefQuest), 81.05% of participants reported experience of LD once or more. Concerning the questionnaire based on LD indicators (AwarContQuest), 73.38% of participants reported having experienced LD once or more. However, with regard to the correlations analysis, links between LD prevalence and factors such as Vividness of Mental Imagery and Parasomnia, varied across questionnaires. This result is an argument suggesting that researchers should be careful when investigating links between LD and other factors. The type of methodology may influence findings on LD research. Further studies are needed to investigate on the methodology effect in LD research namely on the respective weight of

  1. Moessbauer and Electron Microprobe Studies of Density Separates of Martian Nakhlite Mil03346: Implications for Interpretation of Moessbauer Spectra Acquired by the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; McKay, G. A.; Agresti, D. G.; Li, Loan

    2008-01-01

    Martian meteorite MIL03346 is described as an augite-rich cumulate rock with approx.80%, approx.3%, and approx.21% modal phase proportions of augite (CPX), olivine and glassy mesostasis, respectively, and is classified as a nakhlite [1]. The Mossbauer spectrum for whole rock (WR) MIL 03346 is unusual for Martian meteorites in that it has a distinct magnetite subspectrum (7% subspectral area) [2]. The meteorite also has products of pre-terrestrial aqueous alteration ("iddingsite") that is associated primarily with the basaltic glass and olivine. The Mossbauer spectrometers on the Mars Exploration Rovers have measured the Fe oxidation state and the Fe mineralogical composition of rocks and soils on the planet s surface since their landing in Gusev Crater and Meridiani Planum in January, 2004 [3,4]. The MIL 03346 meteorite provides an opportunity to "ground truth" or refine Fe phase identifications. This is particularly the case for the so-called "nanophase ferric oxide" (npOx) component. NpOx is a generic name for a ferric rich product of oxidative alteration. On Earth, where we can take samples apart and study individual phases, examples of npOx include ferrihydrite, schwertmannite, akagaaneite, and superparamagnetic (small particle) goethite and hematite. It is also possible for ferric iron to be associated to some unknown extent with igneous phases like pyroxene. We report here an electron microprobe (EMPA) and Moessbauer (MB) study of density separates of MIL 03346. The same separates were used for isotopic studies by [5]. Experimental techniques are described by [6,7].

  2. Field site investigation: Effect of mine seismicity on groundwater hydrology

    SciTech Connect

    Ofoegbu, G.I.; Hsiung, S.; Chowdhury, A.H.; Philip, J.

    1995-04-01

    The results of a field investigation on the groundwater-hydrologic effect of mining-induced earthquakes are presented in this report. The investigation was conducted at the Lucky Friday Mine, a silver-lead-zinc mine in the Coeur d`Alene Mining District of Idaho. The groundwater pressure in sections of three fracture zones beneath the water table was monitored over a 24-mo period. The fracture zones were accessed through a 360-m-long inclined borehole, drilled from the 5,700 level station of the mine. The magnitude, source location, and associated ground motions of mining-induced seismic events were also monitored during the same period, using an existing seismic instrumentation network for the mine, augmented with additional instruments installed specifically for the project by the center for Nuclear Waste Regulatory Analyses (CNWRA). More than 50 seismic events of Richter magnitude 1.0 or larger occurred during the monitoring period. Several of these events caused the groundwater pressure to increase, whereas a few caused it to decrease. Generally, the groundwater pressure increased as the magnitude of seismic event increased; for an event of a given magnitude, the groundwater pressure increased by a smaller amount as the distance of the observation point from the source of the event increased. The data was examined using regression analysis. Based on these results, it is suggested that the effect of earthquakes on groundwater flow may be better understood through mechanistic modeling. The mechanical processes and material behavior that would need to be incorporated in such a model are examined. They include a description of the effect of stress change on the permeability and water storage capacity of a fracture rock mass; transient fluid flow; and the generation and transmission of seismic waves through the rock mass.

  3. Investigating the neural correlates of the Stroop effect with magnetoencephalography.

    PubMed

    Galer, Sophie; Op De Beeck, Marc; Urbain, Charline; Bourguignon, Mathieu; Ligot, Noémie; Wens, Vincent; Marty, Brice; Van Bogaert, Patrick; Peigneux, Philippe; De Tiège, Xavier

    2015-01-01

    Reporting the ink color of a written word when it is itself a color name incongruent with the ink color (e.g. "red" printed in blue) induces a robust interference known as the Stroop effect. Although this effect has been the subject of numerous functional neuroimaging studies, its neuronal substrate is still a matter of debate. Here, we investigated the spatiotemporal dynamics of interference-related neural events using magnetoencephalography (MEG) and voxel-based analyses (SPM8). Evoked magnetic fields (EMFs) were acquired in 12 right-handed healthy subjects performing a color-word Stroop task. Behavioral results disclosed a classic interference effect with longer mean reaction times for incongruent than congruent stimuli. At the group level, EMFs' differences between incongruent and congruent trials spanned from 380 to 700 ms post-stimulus onset. Underlying neural sources were identified in the left pre-supplementary motor area (pre-SMA) and in the left posterior parietal cortex (PPC) confirming the role of these regions in conflict processing. PMID:24752907

  4. Electrically heated tube investigation of cooling channel geometry effects

    NASA Technical Reports Server (NTRS)

    Meyer, Michael L.

    1995-01-01

    The results of an experimental investigation on the combined effects of cooling channel aspect ratio and curvature for rocket engines are presented. Symmetrically heated tubes with average heat fluxes up to 1.7 MW/m(exp 2) were used. The coolant was gaseous nitrogen at an inlet temperature of 280 K (500 R) and inlet pressures up to 1.0 x 10(exp 7) N/m(exp 2) (1500 psia). Two different tube geometries were tested: a straight, circular cross-section tube, and an aspect-ratio 10 cross-section tube with a 45 deg bend. The circular tube results are compared to classical models from the literature as validation of the system. The curvature effect data from the curved aspect-ratio 10 tube compare favorably to the empirical equations available in the literature for low aspect ratio tubes. This latter results suggest that thermal stratification of the coolant due to diminished curvature effect mixing may not be an issue for high aspect-ratio cooling channels.

  5. Investigating the effects of target heterogeneity on the cratering process.

    NASA Astrophysics Data System (ADS)

    Barnouin, O. S.

    2012-12-01

    momentum using a second order multi-material Eulerian methodology. This code possesses an adaptive mesh refinement that allows investigating the effects of fine-scale target heterogeneity on the cratering process, through the use of a simple microscopic model with complex but resolvable heterogeneous geometries, rather than a complex macroscopic model. Both approaches provide insights on how the thickness of the shock front relative to the average dimension of any pre-exiting structure could be a controlling factor during impact cratering.

  6. Rheological investigation of highly filled polymers: Effect of molecular weight

    NASA Astrophysics Data System (ADS)

    Hnatkova, Eva; Hausnerova, Berenika; Hales, Andrew; Jiranek, Lukas; Vera, Juan Miguel Alcon

    2015-04-01

    The paper deals with rheological properties of highly filled polymers used in powder injection molding. Within the experimental framework seven PIM feedstocks based on superalloy Inconel 718 powder were prepared. Each feedstock contains the fixed amount of powder loading and the same composition of binder system consisting of three components: polyethylene glycol (PEG) differing in molecular weight, poly (methyl methacrylate) (PMMA) and stearic acid (SA). The aim is to investigate the influence of PEG's molecular weight on the flow properties of feedstocks. Non-Newtonian indices, representing the shear rate sensitivity of the feedstocks, are obtained from a polynomial fit, and found to vary within measured shear rates range from 0.2 to 0.8. Temperature effect is considered via activation energies, showing decreasing trend with increasing of molecular weight of PEG (except of feedstock containing 1,500 g.mol-1 PEG).

  7. Computational Investigation of Dynamic Glottal Aperture Effects on Respiratory Airflow

    NASA Astrophysics Data System (ADS)

    Xi, Jinxiang; Yan, Hong; Dong, Haibo

    2008-11-01

    The periodic movement of the glottal aperture (vocal folds) during tidal breathing has been long recognized as a factor in altering the airflow dynamics in the tracheobrnchial region. The potential influence from these altered flow structures on the transport and deposition of inhaled particles is not known. However, studies devoted to this dynamic physiological feature are scarce due to the complex anatomy in of the larynx and numerical challenges in simulating dynamic geometries. In this study, a high-fidelity immersed boundary solver is used to investigate this problem. A 3D human oral-larynx-lung model is firstly reconstructed from MRI data. The role of the vocal fold movement and associated airflow characteristics such as vortex shedding, Coanda effect etc. during inhalation and exhalation are then numerically studied.

  8. Effective field investigation in arrays of polycrystalline ferromagnetic nanowires

    NASA Astrophysics Data System (ADS)

    Hernández, Eduardo Padrón; Rezende, S. M.; Azevedo, A.

    2008-04-01

    Nanowire arrays have been used as prototypes to investigate basic issues such as size effect, shape anisotropy, and dipolar interaction on the magnetic properties. Under ideal conditions, the nanowires are approximated as perfect long cylinders. Here, coherent rotation as the magnetization reversal mode cannot completely interpret the experimental data. The internal magnetic field value, in nanowire arrays, decreases due to the wire inhomogeneities and the dipolar interaction between the wires. Realistic models must account for the imperfections due to the fabrication process. Instead of it, in this work, a modified ellipsoid-chain array model is proposed to describe magnetization reversal in nanowire arrays. From the angular dependence of the ferromagnetic resonance field presented previously in the literature and from our proper results here, we present experimental confirmations to the model.

  9. Structural and toxic effect investigation of vanadium pentoxide.

    PubMed

    Yuvakkumar, R; Hong, S I

    2016-08-01

    A facile inorganic complex synthesis route has been developed to synthesis V2O5 nanostructures. The effects of varying incubation time on the crystallinity and morphology of the V2O5 phase has been investigated. The obtained XRD result clearly revealed the pure orthorhombic V2O5 crystalline phase. Raman antiphase bridging VO and chaining VO stretching modes peaks at 686 and 521cm(-1) attributed orthorhombic V2O5 characteristics. The V2p3/2 peak at the binding energies of 517eV and V2p1/2 peak at 524eV assigned to V(5+) oxidation state. Bioinspired V2O5 nanostructures as a biocompatible material for anticancer agents show excellent cytotoxicity at higher V2O5 concentration. PMID:27157769

  10. Investigation of acute stroke: what is the most effective strategy?

    PubMed Central

    Dunbabin, D. W.; Sandercock, P. A.

    1991-01-01

    Techniques of investigation of acute stroke syndromes have progressed rapidly in recent years, outpacing developments in effective stroke treatment. The clinician is thus faced with a variety of tests, each with different cost implications and each altering management to a greater or lesser extent. This review will concentrate on the basic tests which should be performed for all strokes (full blood count, ESR, biochemical screen, blood glucose, cholesterol, syphilis serology, chest X-ray and electrocardiogram). Additional tests may be required in selected cases: CT scan to diagnose 'non-stroke' lesions, to exclude cerebral haemorrhage if anti-haemostatic therapy is planned, and to detect strokes which may require emergency intervention (such as cerebellar stroke with hydrocephalus); echocardiography to detect cardiac sources of emboli; and in a few cases lumbar puncture and specialized haematological tests. Other tests, which are currently research tools, may be suitable for widespread use in the future including NMR, SPECT and PET scanning. PMID:2062773

  11. Investigation of temperature effect on cell mechanics by optofluidic microchips

    PubMed Central

    Yang, Tie; Nava, Giovanni; Minzioni, Paolo; Veglione, Manuela; Bragheri, Francesca; Lelii, Francesca Demetra; Vazquez, Rebeca Martinez; Osellame, Roberto; Cristiani, Ilaria

    2015-01-01

    Here we present the results of a study concerning the effect of temperature on cell mechanical properties. Two different optofluidic microchips with external temperature control are used to investigate the temperature-induced changes of highly metastatic human melanoma cells (A375MC2) in the range of ~0 – 35 °C. By means of an integrated optical stretcher, we observe that cells’ optical deformability is strongly enhanced by increasing cell and buffer-fluid temperature. This finding is supported by the results obtained from a second device, which probes the cells’ ability to be squeezed through a constriction. Measured data demonstrate a marked dependence of cell mechanical properties on temperature, thus highlighting the importance of including a proper temperature-control system in the experimental apparatus. PMID:26309762

  12. Investigation of Compressibility Effect for Aeropropulsive Shear Flows

    NASA Technical Reports Server (NTRS)

    Balasubramanyam, M. S.; Chen, C. P.

    2005-01-01

    Rocket Based Combined Cycle (RBCC) engines operate within a wide range of Mach numbers and altitudes. Fundamental fluid dynamic mechanisms involve complex choking, mass entrainment, stream mixing and wall interactions. The Propulsion Research Center at the University of Alabama in Huntsville is involved in an on- going experimental and numerical modeling study of non-axisymmetric ejector-based combined cycle propulsion systems. This paper attempts to address the modeling issues related to mixing, shear layer/wall interaction in a supersonic Strutjet/ejector flow field. Reynolds Averaged Navier-Stokes (RANS) solutions incorporating turbulence models are sought and compared to experimental measurements to characterize detailed flow dynamics. The effect of compressibility on fluids mixing and wall interactions were investigated using an existing CFD methodology. The compressibility correction to conventional incompressible two- equation models is found to be necessary for the supersonic mixing aspect of the ejector flows based on 2-D simulation results. 3-D strut-base flows involving flow separations were also investigated.

  13. Investigation of the size effect for photonic crystals.

    PubMed

    Liu, M; Xu, W; Bai, J; Chua, C K; Wei, J; Li, Z; Gao, Y; Kim, D H; Zhou, K

    2016-10-01

    Three types of photonic crystal (PC) thin films have been prepared for the investigation of their deformation behaviors by nanoindentation tests at the microscale and nanoscale. Each type of PC thin film was composed of poly(methyl methacrylate) (PMMA) nanoparticles with a uniform size. Another type of thin film was prepared by assembling nanoparticles with three different sizes. It was exciting to observe that the hardness and Young's modulus were significantly improved (more than 15 times) in well-ordered PC thin films than disordered ones. Furthermore, size-dependent mechanical properties were observed for the three types of PCs. Such a size effect phenomenon can be attributed to the special polycrystalline material having a periodical face-centered cubic structure of PC thin films. Furthermore, the indentation size effect that shows that the indentation hardness decreases with an increasing indentation depth has also been observed for all four types of thin films. It is conjectured that the application of the PC structure to other functional materials may enhance their mechanical properties. PMID:27577061

  14. Computational Investigation of Extended-MHD Effects on Tokamak Plasmas

    NASA Astrophysics Data System (ADS)

    King, Jacob R.; Kruger, Scott E.

    2013-10-01

    We present studies with the extended-MHD NIMROD code of the tearing instability and edge-localized modes (ELMs). In our first study we use analytics and computations to examine tearing in a large-guide field with a nonzero pressure gradient where previous results show drift effects are stabilizing [Coppi, PoF (1964)]. Our work finds three new results: (1) At moderately large ion gyroradius the mode rotates at the electron drift velocity and there is no stabilization. (2) With collision-less drift reconnection, computations must also include electron gyroviscosity and advection. And (3) we derive a dispersion relation that exhibits diamagnetic stabilization and describes the transition between the electron-fluid-mediated regime of (1) and the semi-collisional regime [Drake and Lee, PoF (1977)]. Our second study investigates the transition from an ideal- to an extended-MHD model in an ELM unstable tokamak configuration. With the inclusion of a full generalized Ohm's law the growth rate is enhanced at intermediate wave-numbers and cut-off at large wave-numbers by diamagnetic effects consistent with analytics [Hastie et al., PoP (2003)]. Adding ion gyroviscosity to the model is stabilizing at large wave-numbers consistent with recent results [Xu et al., PoP (2013)]. Support provided by US DOE.

  15. Investigation of microgravity effects on solidification phenomena of selected materials

    NASA Technical Reports Server (NTRS)

    Maag, Carl R.; Hansen, Patricia A.

    1992-01-01

    A Get Away Special (GAS) experiment payload to investigate microgravity effects on solidification phenomena of selected experimental samples has been designed for flight. It is intended that the first flight of the assembly will (1) study the p-n junction characteristics for advancing semiconductor device applications, (2) study the effects of gravity-driven convection on the growth of HgCd crystals, (3) compare the textures of the sample which crystallizes in microgravity with those found in chondrite meteorites, and (4) modify glass optical characteristics through divalent oxygen exchange. The space flight experiment consists of many small furnaces. While the experiment payload is in the low gravity environment of orbital flight, the payload controller will sequentially activate the furnaces to heat samples to their melt state and then allow cooling to resolidification in a controlled fashion. The materials processed in the microgravity environment of space will be compared to the same materials processed on earth in a one-gravity environment. This paper discusses the design of all subassemblies (furnance, electronics, and power systems) in the experiment. A complete description of the experimental materials is also presented.

  16. A Backscatter Moessbauer Spectrometer (BaMS) for use on Mars

    NASA Technical Reports Server (NTRS)

    Agresti, D. G.; Morris, R. V.; Wills, E. L.; Shelfer, T. D.; Pimperl, M. M.; Shen, M.-H.; Nguyen, T.

    1992-01-01

    The use of Moessbauer spectroscopy for in situ analysis on the surface of Mars was proposed and the design and implementation of a backscatter Moessbauer spectrometer (BaMS) instrument suitable for planetary missions to the surfaces of Mars (MESUR), the Moon (Artemis and lunar outpost), asteroids, or other solid solar system objects is discussed. The BaMS instrument is designed to be capable of analysis of a sample for the mineralogy of its iron-bearing phases without any sample preparation. A requirement of lander missions to Mars is instrumentation for in situ mineralogical analyses. Such analyses provide data needed for primary characterization as to the type of surface materials present and by inference the processes that formed and subsequently modified them. For purposes of providing diagnostic information about naturally occurring materials, the element iron is particularly important because it is abundant and multivalent (primarily 0, +2, and +3 oxidation states). Knowledge of the oxidation state of iron and its distribution among iron-bearing mineralogies tightly constrains the types of materials present. The pivotal role of iron was already recognized in 1978 by COMPLEX, who recommended development of flight instruments that would identify mineralogy and the oxidation state of iron in planetary surface materials. The near-term U.S. strategy for the exploration of Mars is the MESUR (Mars Environmental SURvey) program, which entails emplacement of a network of small, long-lived surface landers. For the Moon, BaMS was recommended as part of a three-instrument landed payload for the Artemis missions, targeted for 1997. BaMS would prospect for ilmenite, an oxygen resource material, and provide data to assess the maturity of lunar soil. Because instrumental characteristics are low mass, low volume, and low power consumption, BaMS is suitable for implementation on even small landers and rovers, as are being envisioned in MESUR and Artemis concepts. In addition

  17. Experimental investigation of vitiation effects on supersonic combustor performance

    NASA Astrophysics Data System (ADS)

    Li, Jianping; Song, Wenyan; Luo, Feiteng; Shi, Deyong

    2014-03-01

    A significant problem for use of combustion heated facilities in ground laboratory studies of scramjet propulsion is that the resulting high enthalpy test air are seriously vitiated by several species, for example, H2O, CO2, CO, H, OH, O, and NO, which are not of representative or very few in actual atmosphere, so-called vitiation air relative to pure air. Combustion in such vitiation air stream can be influenced by chemical and physical effects due to the different species from actual atmosphere. Therefore, the ground-test results from such vitiated facilities should be properly analyzed and corrected before extrapolated to atmospheric flight condition. The primary goal of the present efforts is to assess the net effects of vitiation air on combustion process in a supersonic combustor. Based on the direct-connected test facility of Northwestern Polytechnical University, an experimental system is developed for comparative investigation of supersonic combustion in vitiation airstream and clean airstream, respectively. Specific species at well-controlled concentration are added to the clean airstream generated from resistance heater to synthesize the vitiation airstream, duplicating the test media in a combustion heated facility. The air total temperature at combustor entrance is about 850 K, typically simulating the Mach 4 flight condition. Details of the experiment system are present in this paper. With the newly constructing system, hydrogen, ethylene and kerosene fueled supersonic combustions with clean air and vitiation air stream are investigated. Individual and combined influences of H2O and CO2 at various concentrations are considered over a range of experiment condition. The combustion characteristics with clean and vitiation air stream are compared, and the influences of H2O and H2O/CO2 on supersonic combustion processes are discussed. Results show that, the combustion induced pressure rise can be significantly inhibited by H2O and/or CO2 vitiation . The

  18. Investigating binding particles distribution effects on polymer translocation through nanopore

    NASA Astrophysics Data System (ADS)

    Haji Abdolvahab, Rouhollah

    2016-03-01

    Chaperone driven polymer translocation is an important model for biopolymer's translocation in vivo. Binding proteins spatial distribution is a significant factor in calculating the translocation time of the polymer in this type of translocation. Here using a dynamical Monte Carlo simulation we compare the results of the usual uniform distribution with the exponential distribution of different rates for a stiff polymer. Our simulation results show that just by changing the chaperones spatial distribution the translocation time of the biopolymer will change by as large as an order. It can change the translocation regime of the polymer completely from a diffusive to a ballistic one. Although generally increasing the exponential rate and the background concentration will increase the translocation velocity, it is not always true and one should consider both the sequence and the background concentration. We show that the results depend on the sequence and changing the distribution rates for increasing the translocation velocity will change the whole Probability Density Function (PDF) of the polymer translocation time accordance to its sequence. The translocation time sequence dependency will change in the extreme cases e.g. in the high exponential rate. Investigating the binding protein size, λ, also shows the importance of the so called parking lot effect in distribution dependency of the translocation velocity. Although there is not any important dependency for λ = 1, translocation time depends clearly on the chaperone spatial distribution for the case of λ ≥ 2.

  19. Investigations on birefringence effects in polymer optical fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Hu, X.; Sáez-Rodríguez, D.; Bang, O.; Webb, D. J.; Caucheteur, C.

    2014-05-01

    Step-index polymer optical fiber Bragg gratings (POFBGs) and microstructured polymer optical fiber Bragg gratings (mPOFBGs) present several attractive features, especially for sensing purposes. In comparison to FBGs written in silica fibers, they are more sensitive to temperature and pressure because of the larger thermo-optic coefficient and smaller Young's modulus of polymer materials. (M)POFBGs are most often photowritten in poly(methylmethacrylate) (PMMA) materials using a continuous-wave 325 nm HeCd laser. For the first time to the best of our knowledge, we study photoinduced birefringence effects in (m)POFBGs. To achieve this, highly reflective gratings were inscribed with the phase mask technique. They were then monitored in transmission with polarized light. For this, (m)POF sections a few cm in length containing the gratings were glued to angled silica fibers. Polarization dependent loss (PDL) and differential group delay (DGD) were computed from the Jones matrix eigenanalysis using an optical vector analyser. Maximum values exceeding several dB and a few picoseconds were obtained for the PDL and DGD, respectively. The response to lateral force was finally investigated. As it induces birefringence in addition to the photo-induced one, an increase of the PDL and DGD values were noticed.

  20. Pharmacological investigation of memory restorative effect of riluzole in mice

    PubMed Central

    Rinwa, Puneet; Jaggi, Amteshwar Singh; Singh, Nirmal

    2012-01-01

    Objective: Streptozotocin (STZ) and sodium nitrite (NaNO2) treatment have been positively correlated with higher incidence of memory loss and experimental dementia. The present study was designed to investigate the potential of the Riluzole, an inhibitor of glutamatergic neurotransmission and activator of TWIK-Related K+ channels with incidences of memory deficits associated with dementia in mice. Materials and Methods: Dementia was induced in Swiss albino mice by intracerebroventricular STZ (ICV) and by subcutaneous NaNO2 in separate groups of animals. Morris water maze was employed to assess learning and memory of the animals. Biochemical analysis of brain homogenate was performed so as to assess brain acetyl cholinesterase (AChE) activity. Brain thiobarbituric acid reactive species (TBARS) levels and reduced glutathione (GSH) levels were measured to assess total oxidative stress. Results: Treatment of ICV STZ and NaNO2 produced a significant decrease in water maze performance of mice hence reflecting loss of learning and memory. Furthermore, higher levels of brain AChE activity and oxidative stress were observed in these animals. Administration of riluzole (5 and 10 mg/kg intraperitoneally) successfully attenuated memory deficits as well as ICV STZ- and NaNO2 -induced changes in the levels of brain AChE, TBARS, and GSH. Conclusion: The memory restorative effects of riluzole in dementia may involve its multiple functions including anti-oxidative and anticholinesterase properties. PMID:22701248

  1. Friction microprobe investigation of particle layer effects on sliding friction

    SciTech Connect

    Blau, P.J.

    1993-01-01

    Interfacial particles (third-bodies), resulting from wear or external contamination, can alter and even dominate the frictional behavior of solid-solid sliding in the absence of effective particle removal processes (e.g., lubricant flow). A unique friction microprobe, developed at Oak Ridge National Laboratory, was used to conduct fine- scale friction studies using 1.0 mm diameter stainless steel spheres sliding on several sizes of loose layers of fine aluminum oxide powders on both aluminum and alumina surfaces. Conventional, pin-on-disk experiments were conducted to compare behavior with the friction microprobe results. The behavior of the relatively thick particle layers was found to be independent of the nature of underlying substrate, substantiating previous work by other investigators. The time-dependent behavior of friction, for a spherical macrocontact starting from rest, could generally be represented by a series of five rather distinct phases involving static compression, slider breakaway, transition to steady state, and dynamic layer instability. A friction model for the steady state condition, which incorporates lamellar powder layer behavior, is described.

  2. Experimental Investigation on Effect of Adhesives on Thermoelectric Generator Performance

    NASA Astrophysics Data System (ADS)

    Singh, Baljit; Remeli, Muhammad Fairuz; Chet, Ding Lai; Oberoi, Amandeep; Date, Abhijit; Akbarzadeh, Aliakbar

    2015-06-01

    Thermoelectric generators (TEGs) convert heat energy into electricity. Currently, these devices are attached to heat exchangers by means of mechanical devices such as clamps or fixtures with nuts and bolts. These mechanical devices are not suitable for use in harsh environments due to problems with rusting and maintenance. To eliminate the need for such mechanical devices, various kinds of adhesives used to attach thermoelectric generators to heat exchangers are investigated experimentally in this work. These adhesives have been selected based on their thermal properties and also their stability to work in harsh environments to avoid damage to the integrity of the attachment over long periods of time. Stainless-steel plates were attached to a thermoelectric generator using the adhesives. The introduction of the adhesive as a means of attachment for thermoelectric generators contributes to increase the thermal resistance to heat transfer across the TEG. The adhesive layers increased the thermal resistance of the thermoelectric generator by 16% to 109%. This work examines the effect of the adhesives on the thermal performance and power output of a single thermoelectric generator for various heat inputs.

  3. Moessbauer spectroscopy studies of iron-catalysts used in Fischer-Tropsch (FT) processes. Quarterly technical progress report, October 1, 1996--December 31, 1996

    SciTech Connect

    Huffman, G.P.; Rao, K.R.P.M.

    1996-12-31

    The U.S. Department of Energy has currently a program to develop Fischer-Tropsch catalysts which are active at low H{sub 2}/Co ratio of 0.67. The Center for Applied Energy Research, University of Kentucky and Texas A&M University have been developing Fischer- Tropsch catalysts which are active at a low H{sub 2}/Co ratio of 0.67. It is of interest to find out any relationships that may exist between the iron phases that are produced during activation and FT synthesis and the activity of the catalysts. Moessbauer spectroscopy investigations were carried out on 32 iron-base catalysts during the period under review. Eleven catalysts withdrawn from slurry type of reactors during and at the end of FT synthesis were received from the University of Kentucky. Twenty one catalysts withdrawn at the end of the run from both the slurry and fixed-bed reactors were received from Texas A&M University.

  4. Magnetic and Moessbauer studies of Apollo 16 rock chips 60315,51 and 62295,27

    NASA Technical Reports Server (NTRS)

    Brecher, A.; Vaughan, D. J.; Burns, R. G.

    1973-01-01

    Analysis of the Moessbauer spectra of two Apollo 16 rocks showed that 60315,51 is much richer in iron metal and troilite, but poorer in olivine, than 62295,27. The values of magnetic parameters, derived from hysteresis loops at 175 and 300 K, indicate the high metal contents and the predominance of coarse multidomain grains in both rocks. These coexist with a superparamagnetic grain fraction in 60315 and with a small single-domain grain fraction in 62295. The high Fe(0)/Fe(2+) ratios, the nonlinear acquisition of laboratory thermoremanence, and the drastic changes in magnetic parameters upon heating support the proposed formation of both rocks from the lunar regolith, with incorporation of shocked meteoritic metal grains during high-temperature impact events and simultaneous acquisition of magnetic remanence. Values estimated for ancient lunar magnetic fields by comparing the natural remanence with laboratory thermoremanence acquired in fields of 0.05 and 0.5 Oe, range from 0.01 to more than 1 Oe.

  5. Chemical decomposition of iron in Spanish coal pyrolysis identified by Moessbauer spectroscopy at different temperatures

    SciTech Connect

    Ahmed, M.A.; Blesa, M.J.; Moliner, R.

    2007-07-01

    Three chars from lignite (Se), sub bituminous (AA6), bituminous (BCA) Spanish coals produced at 673 K, 773 K, and 873 K were analyzed by Moessbauer spectroscopy at room temperature, and 80 K, except BCA char produced at 873 K, its analysis was extended down to 10 K. Least square fit analysis for the spectra of Se chars showed that, jarosite/Fe{sup 3+} was hydrolyzed into rozenite/Fe2+ at 873 K. Pyrite was reduced to troilite (FeS) at 773 K. Both jarosite and very broad doublet were observed at T = 673 K. The hyperfine parameters of this phase gave close values to microcrystalline iron in either Fe (II) or Fe (III) states. On the other hand, the spectral analysis of AA6 chars ascertained that rozenite was hydrolyzed to goethite (FeOOH) in the range of 773 K-873 K, whereas pyrite was reduced to pyrrohotite (Fe{sub 1-x}S). However, no chemical changes were observed for jarosite in all AA6-chars. Likewise, siderite was changed into magnetite in the BCA chars produced at 673 K and 773 K. Spectrum performed at 10 K for char produced at 873 K proved the presence of ferrihydrite (H = 489.2 kOe), troilite (H = 355.3 kOe) and a broad paramagnetic doublet belonging to an organic iron. These phases and still remaining siderite inferred also that such transformations are incomplete.

  6. Applying Kalman filtering to investigate tropospheric effects in VLBI

    NASA Astrophysics Data System (ADS)

    Soja, Benedikt; Nilsson, Tobias; Karbon, Maria; Heinkelmann, Robert; Liu, Li; Lu, Cuixian; Andres Mora-Diaz, Julian; Raposo-Pulido, Virginia; Xu, Minghui; Schuh, Harald

    2014-05-01

    Very Long Baseline Interferometry (VLBI) currently provides results, e.g., estimates of the tropospheric delays, with a delay of more than two weeks. In the future, with the coming VLBI2010 Global Observing System (VGOS) and increased usage of electronic data transfer, it is planned that the time between observations and results is decreased. This may, for instance, allow the integration of VLBI-derived tropospheric delays into numerical weather prediction models. Therefore, future VLBI analysis software packages need to be able to process the observational data autonomously in near real-time. For this purpose, we have extended the Vienna VLBI Software (VieVS) by a Kalman filter module. This presentation describes the filter and discusses its application for tropospheric studies. Instead of estimating zenith wet delays as piece-wise linear functions in a least-squares adjustment, the Kalman filter allows for more sophisticated stochastic modeling. We start with a random walk process to model the time-dependent behavior of the zenith wet delays. Other possible approaches include the stochastic model described by turbulence theory, e.g. the model by Treuhaft and Lanyi (1987). Different variance-covariance matrices of the prediction error, depending on the time of the year and the geographic latitude, have been tested. In winter and closer to the poles, lower variances and covariances are appropriate. The horizontal variations in tropospheric delays have been investigated by comparing three different strategies: assumption of a horizontally stratified troposphere, using north and south gradients modeled, e.g., as Gauss-Markov processes, and applying a turbulence model assuming correlations between observations in different azimuths. By conducting Monte-Carlo simulations of current standard VLBI networks and of future VGOS networks, the different tropospheric modeling strategies are investigated. For this purpose, we use the simulator module of VieVS which takes into

  7. Experimental Investigation of Ice Accretion Effects on a Swept Wing

    NASA Technical Reports Server (NTRS)

    Papadakis, M.; Yeong, H. W.; Wong, S. C.; Vargas, M.; Potapczuk, M.

    2005-01-01

    An experimental investigation was conducted to study the effects of 2-, 5-, 10-, and 22.5-min ice accretions on the aerodynamic performance of a swept finite wing. The ice shapes tested included castings of ice accretions obtained from icing tests at the NASA Glenn Icing Research Tunnel (IRT) and simulated ice shapes obtained with the LEWICE 2.0 ice accretion code. The conditions used for the icing tests were selected to provide five glaze ice shapes with complete and incomplete scallop features and a small rime ice shape. The LEWICE ice shapes were defined for the same conditions as those used in the icing tests. All aerodynamic performance tests were conducted in the 7- x 10-ft Low-Speed Wind Tunnel Facility at Wichita State University. Six component force and moment measurements, aileron hinge moments, and surface pressures were obtained for a Reynolds number of 1.8 million based on mean aerodynamic chord and aileron deflections in the range of -15o to 20o. Tests were performed with the clean wing, six IRT ice shape castings, seven smooth LEWICE ice shapes, and seven rough LEWICE ice shapes. Roughness for the LEWICE ice shapes was simulated with 36-size grit. The experiments conducted showed that the glaze ice castings reduced the maximum lift coefficient of the clean wing by 11.5% to 93.6%, while the 5-min rime ice casting increased maximum lift by 3.4%. Minimum iced wing drag was 133% to 3533% greater with respect to the clean case. The drag of the iced wing near the clean wing stall angle of attack was 17% to 104% higher than that of the clean case. In general, the aileron remained effective in changing the lift of the clean and iced wings for all angles of attack and aileron deflections tested. Aileron hinge moments for the iced wing cases remained within the maximum and minimum limits defined by the clean wing hinge moments. Tests conducted with the LEWICE ice shapes showed that in general the trends in aerodynamic performance degradation of the wing with

  8. Investigating effect of microemulsion components: In vitro permeation of ketoconazole.

    PubMed

    Patel, Mrunali R; Patel, Rashmin B; Parikh, Jolly R; Solanki, Ajay B; Patel, Bharat G

    2011-06-01

    The purpose of this study was to evaluate the effect of oil, surfactant/co-surfactant mixing ratios and water on the in vitro permeation of ketoconazole (KTZ) applied in O/W microemulsion vehicle through intact rat skin. Lauryl Alcohol (LA) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulsion system. The pseudo-ternary phase diagrams for microemulsion regions were constructed using LA as the oil, Labrasol (Lab) as the surfactant (S) and ethanol (EtOH) as the cosurfactant (CoS). The formulation which showed a highest permeation rate of 54.65 ± 1.72 µg/cm(2)/h(1) and appropriate physico-chemical properties was optimized as containing 2% KTZ, 10% LA, 20% Lab/EtOH (1:1) and 68% double distilled water (w/w). The efficiency of microemulsion formulation in the topical delivery of KTZ was dependent upon the contents of water and LA as well as Lab/EtOH mixing ratio. It was concluded that the percutaneous absorption of KTZ from microemulsions was enhanced with increasing the LA and water contents, and with decreasing the Lab/EtOH ratio in the formulation. Candida albicans was used as a model fungus to evaluate the antifungal activity of the best formula achieved, which showed the widest zone of inhibition as compared to KTZ reference. The studied microemulsion formulation showed a good stability for a period of three months. Histopathological investigation of rat skin revealed the safety of microemulsion formulations for topical use. These results indicate that the studied microemulsion formulation might be a promising vehicle for topical delivery of KTZ. PMID:20146553

  9. Investigation of bias radiation effect on PV cell measurement

    NASA Astrophysics Data System (ADS)

    Huang, Xuebo; Quan, Chenggen; Chan, Joanne; Ng, Patrick

    2013-06-01

    Photovoltaic (PV) cells are photo-electrical devices that convert light energy directly into electricity through the photovoltaic effect. PV cell assemblies are used to make solar modules employed in a variety of ways ranging from space applications to domestic energy consumption. Characterisation and performance testing of PV cells are critical to the development of PV technologies and growth of the solar industry. As new solar products are being developed, its energy conversion efficiency and other critical parameters must be accurately measured and tested against globally recognised metrological standards. The differential spectral responsivity (DSR) measurement is one of the primary methods for calibrating reference PV cells. This is done by calculating its spectral responsivities through measuring the AC short-circuit current produced by a PV cell under a modulated monochromatic radiation and different levels of steady-state broadband bias light radiation. It is observed that different types of bias light source will produce different signal-to-noise levels and significantly influence measurement accuracy. This paper aims to investigate the noise sources caused by different types of bias light sources (e.g. xenon arc and tungsten-halogen lamps) and the relevant measurement uncertainties so as to propose a guideline for selection of bias light source which can improve the signal-to-noise level and measurement uncertainty. The DSRs of the PV cells are measured using a commercial DSR measurement system under different levels of bias radiation from 0 to 1 kWm-2. The data analysis and uncertainty evaluation are presented in this paper using experimental data and mathematical tools.

  10. Investigating Halo and Ceiling Effects in Student Evaluations of Instruction

    ERIC Educational Resources Information Center

    Keeley, Jared W.; English, Taylor; Irons, Jessica; Henslee, Amber M.

    2013-01-01

    Many measurement biases affect student evaluations of instruction (SEIs). However, two have been relatively understudied: halo effects and ceiling/floor effects. This study examined these effects in two ways. To examine the halo effect, using a videotaped lecture, we manipulated specific teacher behaviors to be "good" or "bad"…

  11. Porosimetry as an effective method of fuel cell investigation

    SciTech Connect

    Kazarinov, V.E.

    1996-04-01

    A porosimetric method is described for the investigation of all kinds of porous materials including soft or frail materials and powders. The method is well suited for the investigation of electrodes in fuel cells and batteries. The method is nondestructive and allows for repeated measurements on the same sample.

  12. Investigation of the potential immunomodulatory effects of resveratrol on equine whole blood: An in vitro investigation.

    PubMed

    Martin, Lynn M; Johnson, Philip J; Amorim, Juliana R; Honaker, Allison R; Donaldson, Rebecca S; DeClue, Amy E

    2016-06-01

    Horses affected with gastrointestinal conditions such as colic or colitis are at substantial risk for translocation of bacterial components such as lipopolysaccharide (LPS, endotoxin) from the gastrointestinal tract into circulation resulting in systemic inflammation and subsequent morbidity and mortality. Therefore, there is a need for effective preventive and treatment strategies aimed at minimizing the host's inflammatory reaction to these pathogen-associated molecular patterns (PAMPs) from gastrointestinal disease. Resveratrol (RES, trans-3,5,4'-trihydroxystilbene) is a phytoalexin commonly found in fruits and beverages, including red wine. Health benefits associated with the consumption of red wine have been attributed to RES. Resveratrol has been significantly shown to exert a powerful anti-inflammatory effect in laboratory animals subjected to experimental endotoxemia/sepsis. Therefore, the objective of this study was to determine in vitro whether RES had an inhibitory effect on the production of tumor necrosis factor (TNF) in cultivated whole blood (Cwb) following stimulation by PAMPs. We hypothesized that RES would inhibit TNF production in Cwb following stimulation by LPS or lipoteichoic acid (LTA). Production of TNF bioactivity in Cwb was measured in the presence of phosphate buffered saline (control), ethanol (solvent control), dexamethasone (anti-inflammatory control), LPS, LTA, and three different concentrations of RES. Both LPS and LTA stimulated TNF production, and addition of dexamethasone was inhibitory to this effect. An anti-inflammatory effect for RES was not demonstrated under the current experimental conditions. Further studies are required to characterize the effect of RES on the equine innate immune system during systemic inflammation. PMID:27234544

  13. Study of excess Fe metal in the lunar fines by magnetic separation, Moessbauer spectroscopy, and microscopic examination.

    NASA Technical Reports Server (NTRS)

    Housley, R. M.; Grant, R. W.; Abdel-Gawad, M.

    1972-01-01

    A simple and convenient method of making quantitative magnetic separations has been applied to the lunar fines. The fractions obtained form groups containing distinctively different particle types; thus, it appears that magnetic separation in itself many be a useful way of characterizing lunar fines. Moessbauer studies of fines 10084 show that the metal cannot contain more than about 1.5% Ni, implying that by far the bulk of the metal results from reduction rather than from direct meteoritic addition. Microscopic examination of magnetic separates from 15101 fines suggests that reduction of Fe accompanies every major impact event on the moon.

  14. [Investigation of gestagenic effect of raw drone milk in rats].

    PubMed

    Seres, Adrienn; Ducza, Eszter; Gáspár, Róbert

    2014-01-01

    Numerous honeybee products are used in traditional medicine. The best-known honeybee products are the honey, the propolis and the royal jelly. Drone milk is a relatively little-known honeybee product. Although, drone milk is traditionally used to treat infertility and to promote vitality in both men and women in certain countries, the literature furnishes no information concerning effects of the drone milk. The oestrogenic and androgenic effects of drone milk have recently been reported in rats and the effective compounds have also been identified. The aim of this study was to determine the putative gestagenic effect of raw drone milk in rats. Maintenance of pregnancy assays revealed that drone milk was able to increase the number of surviving fetuses. This results suggested some gestagenic effects. This effect was confirmed by RT-PCR and Western blot methods in which the mRNA and protein expressions of gestagen-dependent CRLR (Calcitonin Receptor-Like Receptor) peptide were determined. To determine the efficacy of gestagenic effect of drone milk, spironolactone (weak gestagen compound) was used. The combination of drone milk and spironolactone showed more potent gestagenic effect. These results lead us to suppose that raw drone milk shows weak gestagenic effect and this effect can be increased by another weak gestagen. Further studies are required to clarify the gestagenic mechanisms of action of drone milk. PMID:25167703

  15. Investigation of proximity effects in electron microscopy and lithography

    SciTech Connect

    Walz, M.-M.; Vollnhals, F.; Rietzler, F.; Schirmer, M.; Steinrueck, H.-P.; Marbach, H.

    2012-01-30

    A fundamental challenge in lithographic and microscopic techniques employing focused electron beams are so-called proximity effects due to unintended electron emission and scattering in the sample. Herein, we apply a method that allows for visualizing electron induced surface modifications on a SiN substrate covered with a thin native oxide layer by means of iron deposits. Conventional wisdom holds that by using thin membranes proximity effects can be effectively reduced. We demonstrate that, contrary to the expectation, these can be indeed larger on a 200 nm SiN-membrane than on the respective bulk substrate due to charging effects.

  16. Scale Effect of Model in Seaplane-float Investigations

    NASA Technical Reports Server (NTRS)

    Sottorf, W

    1933-01-01

    For the purpose of solving all the problems involved, an investigation was made with flat, rectangular planing surfaces. The investigation of a flat, rectangular planing surface, which can be considered as the portion of a flat float bottom lying in front of the step, has the advantage that the frictional resistance can be determined directly from the test results. Normal and tangential forces act on the lower side of the planing surface towed through still water, while the upper side and the lateral edges are under constant atmospheric pressure.

  17. Infrared spectroscopic investigations of the compensatoin effect in ceramic materials

    SciTech Connect

    Vanina, E.A.; Kostyukov, N.S.

    1995-09-01

    The objective in this paper was to investigate by means of infrared spectroscopy samples of M-23 electrical porcelain ceramic after irradiation in a BOR-60 reactor with a neutron fluence of 6.5 x 10(exp 21)/square centimeter and isothermal annealing at 700 C and 1000 C for 10 hours. The work was performed on an IKS-29 spectrophotometer using samples in the form of a suspension in vasoline oil and pressed tablets with Potassium Bromide. The investigations were performed after the irradiated samples were allowed to stand for 7 years. It was found that partial amorphization of the quartz occurred.

  18. Iron Mineralogy and Aqueous Alteration on Mars from the MER Moessbauer Spectrometers. Chapter 15

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Klingelhoefer, Goestar

    2007-01-01

    The twin Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) used MIMOS II Moessbauer spectrometers to analyze martian surface materials in the first application of extraterrestrial Moessbauer spectroscopy. The instruments acquired spectra that identified the speciation of Fe according to oxidation state, coordination state, and mineralogical composition and provided quantitative information about the distribution of Fe among oxidation states, coordination states, and Fe-bearing phases. A total of 12 unique Fe-bearing phases were identified: Fe(2+) in olivine, pyroxene, and ilmenite; Fe(2+) and Fe(3+) in magnetite and chromite; Fe(3+) in nanophase ferric oxide (npOx), hematite, goethite, jarosite, an unassigned Fe3+ sulfate, and an unassigned Fe(3+) phase associated with jarosite; and Fe(0) in kamacite. Weakly altered basalts at Gusev crater (SO3 = 2.5 +/- 1.4 wt.% and Fe(3+)/Fe(sub T) = 0.24 +/- 0.11) are widespread on the Gusev plains and occur in less abundance on West Spur and Husband Hill in the Columbia Hills. Altered low-S rocks (SO3 = 5.2 +/- 2.0 wt.% and Fe(3+)/Fe(sub T) = 0.63 +/- 0.18) are the most common type of rock in the Columbia Hills. Ilm-bearing, weakly altered basalts were detected only in the Columbia Hills, as was the only occurrence of chromite in an altered low-S rock named Assemblee. Altered high-S rocks (SO3 > 14.2 wt.% and Fe(3+)/Fe(sub T) = 0.83 +/- 0.05) are the outcrop rocks of the ubiquitous Burns formation at Meridiani Planum. Two Fe(0)-bearing rocks at Meridiani Planum (Barberton and Heat Shield Rock) are meteorites. Laguna Class soil is weakly altered (SO3 = 6 +/- 2 wt.% and Fe(3+)/Fe(sub T) = 0.29 +/- 0.08) and widely distributed at both Gusev crater and Meridiani Planum, implying efficient global mixing processes or a global distribution of precursor rocks with comparable Fe mineralogical compositions. Paso Robles Class soil is heavily altered (SO3 approx. 31 wt.% and Fe(3+)/Fe(sub T) = 0.83 +/- 0

  19. Graduate Assessment Centres: An Empirical Investigation of Effectiveness.

    ERIC Educational Resources Information Center

    Garavan, Thomas N.; Morley, Michael

    1997-01-01

    Effectiveness of assessment centers for personal selection in banking was tested with 135 applicants. Results do not support literature findings of the construct and criterion validity of centers. An exercise effect was apparent: judgments made by assessors were interpretable in terms of the exercises used rather than dimensions related to the…

  20. Interpreting and Reporting Effect Sizes in Research Investigations.

    ERIC Educational Resources Information Center

    Tapia, Martha; Marsh, George E., II

    Since 1994, the American Psychological Association (APA) has advocated the inclusion of effect size indices in reporting research to elucidate the statistical significance of studies based on sample size. In 2001, the fifth edition of the APA "Publication Manual" stressed the importance of including an index of effect size to clarify research…

  1. In-situ Moessbauer Spectroscopy of Supported Iron Fischer-Tropsch Catalysts During Activation

    SciTech Connect

    Motjope, Thato R.; Dlamini, Thulani H.

    2005-04-26

    The behavior of Fe based catalysts supported on ZrO2, SiO2, {gamma}-Al2O3, CeO2 and TiO2 during calcination, reduction and FT synthesis have been studied via in situ Moessbauer spectroscopy. It was found that the type of metal support interaction i.e. surface migration or bulk diffusion during calcination was dependant on the type of support used. Surface migration of Fe3+ during calcination was dominant for ZrO2, CeO2 and {gamma}-Al2O3 and this resulted in the sintering of {alpha}-Fe2O3 crystallites. Whereas bulk diffusion was observed mainly for the catalysts prepared using SiO2 and TiO2, causing a stabilization of the small crystallites of Fe3+ that interacted strongly with the support. Upon reduction, the large crystallites of {alpha}-Fe2O3 were found to reduce readily compared to the small crystallites of Fe3+, except for the catalyst prepared using {gamma}-Al2O3, as a support, where the presence of Al3+ resulted in the formation of spinel like species with the formula (Fe{sup 3+}{sub 2-x}Al{sup 3+}{sub x}Fe{sup 2+})O{sub 4} which are resistant to reduction. Upon exposure to synthesis gas, it was found that catalysts supported on ZrO2 and CeO2 carburized readily resulting in the formation of circa 80% {chi}-Fe2.5C. From this study it was observed that {gamma}-Al2O3 is not the preferred support for Fe based FT catalysts, as it forms the least amount of Fe carbides during FT synthesis.

  2. Moessbauer Spectroscopy for Lunar Resource Assessment: Measurement of Mineralogy and Soil Maturity

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Agresti, D. G.; Shelfer, T. D.; Pimperl, M. M.; Shen, M.-H.; Gibson, M. A.; Wills, E. L.

    1992-01-01

    First-order assessment of lunar soil as a resource includes measurement of its mineralogy and maturity. Soils in which the mineral ilmenite is present in high concentrations are desirable feedstock for the production of oxygen at a lunar base. The maturity of lunar soils is a measure of their relative residence time in the upper 1 mm of the lunar surface. Increasing maturity implies increasing load of solar wind species (e.g., N, H, and He-3), decreasing mean grain size, and increasing glass content. All these physicochemical properties that vary in a regular way with maturity are important parameters for assessing lunar soil as a resource. For example, He-3 can be extracted and potentially used for nuclear fusion. A commonly used index for lunar soil maturity is I(sub s)/FeO, which is the concentration of fine-grained metal determined by ferromagnetic resonance (I(sub s)) normalized to the total iron content (as FeO). I(sub s)/FeO has been measured for virtually every soil returned by the Apollo and Luna missions to the Moon. Because the technique is sensitive to both oxidation state and mineralogy, iron Moessbauer spectroscopy (FeMS) is a viable technique for in situ lunar resource assessment. Its utility for mineralogy is apparent from examination of published FeMS data for lunar samples. From the data published, it can be inferred that FeMS data can also be used to determine soil maturity. The use of FeMS to determine mineralogy and maturity and progress on development of a FeMS instrument for lunar surface use are discussed.

  3. Moessbauer Mineralogical Evidence for Aqueous Processes at Gusev Crater and Meridiani Planum

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Klingelhoefer, G.

    2006-01-01

    The Moessbauer spectrometers on the MER rovers have measured the relative abundances of iron with respect to both oxidation state and iron-bearing phase at Gusev Crater (Spirit rover) and Meridiani Planum (Opportunity rover). The assemblage of phases indicates aqueous alteration processes at both landing sites. Although the rock and soil of the Gusev Crater plains are dominated by Fe(2+) in olivine-bearing basalt (approx.Fo60), a Fe(3+)-rich component (nanophase ferric oxide, np-Ox) has significant abundance in surface soils (13-28% of total Fe) and in the surface coatings (rinds) of certain rocks (39%) but not in rock interiors exposed by grinding (5-6%). The mode of occurrence of np-Ox implies that it is the product of oxidative alteration of Fe(2+) silicate and oxide phases in the presence of H2O. The ubiquitous presence of sulfur in soil and in rock coatings, as determined by the MER-A APXS instrument, suggests that the alteration occurred under acid-sulfate conditions, so that both hydrolytic and sulfatic reactions are viable. A possible source for the weathering agents is volcanic emanations rich in H2O and SO2. Generally, rocks in the Columbia Hills are significantly more altered than those in the Gusev plains, with a higher proportion of Fe(3+) oxide phases compared to Fe(2+) silicate phases. This mineralogical dichotomy implies a difference in the timing, rate, duration, and/or mechanism of alteration for basaltic material in the Gusev plains compared to basaltic material in the Columbia Hills. It is possible, for example, that the basaltic material in the Columbia Hills underwent aqueous alteration in a paleoclimate that favored nearly complete alteration and that the basaltic material of the Gusev plains will not achieve the degree of alteration exhibited by the Columbia Hills under current martian surface conditions.

  4. Investigating Location Effects in a Multicultural Teacher Education Programme

    ERIC Educational Resources Information Center

    Stephenson, Maxine; Anderson, Helen; Rio, Nane; Millward, Pam

    2009-01-01

    This study investigated student perceptions of the significance of having a teacher education programme located in a culturally and ethnically diverse community in New Zealand. Four successive student cohorts were interviewed each year of their teacher preparation, and also during their first year of employment. Students identified location as a…

  5. Investigating Effects of Task Structure on EFL Learner's Oral Performance

    ERIC Educational Resources Information Center

    Rahimpour, Massoud; Mehrang, Faezeh

    2010-01-01

    It is argued that tasks with different structures yield different performances in terms of accuracy, fluency and complexity. The present study is thus an attempt to investigate the impact of task structure on second language task performance. Thirty two upper-intermediate Iranian learners of English performed two narrative tasks (Structured vs.…

  6. An investigation of the effectiveness of asphalt durability tests

    NASA Astrophysics Data System (ADS)

    Predoehl, N. H.; Kemp, G. R.

    1980-05-01

    Included are analyses which show that the effects of voids and aggregate porosity are less severe than the thermal oxidation effect in hot desert climates. A comparison of the results of laboratory tests for predicting asphalt hardening with the results for the field weathered briquettes show that none of the procedures is capable of adequately predicting asphalt weathering in a hot weathering site. A procedure was developed to approximate the effect produced at Indio in two years. Some correlation to briquette results was obtained. A climatic specification to control asphalt hardening in the hot climatic areas is proposed.

  7. Investigating the Effects of Traffic on Air Pollution.

    ERIC Educational Resources Information Center

    Taylor, Sharon

    2001-01-01

    Discusses the benefits of bringing scientists into the classroom to collaborate with children on environmental research projects. Describes one collaborative project that focused on the effects of traffic on air pollution. (DDR)

  8. Dynamical effects in fission investigated at high excitation energy

    NASA Astrophysics Data System (ADS)

    Benlliure, J.

    2016-05-01

    The experimental techniques used for the investigation of nuclear fission have progressed considerably during the last decade. Most of this progress is based on the use of the inverse kinematics technique allowing for the first time the complete isotopic and kinematic characterization of both fission fragments. These measurements make possible to characterize the fissioning system at saddle and at scission, and can be used to benchmark fission model calculations. One of the important ingredients in transport models describing the dynamics of the process is the dissipation parameter, governing the coupling between intrinsic and collective degrees of freedom. Recent experiments got access to the magnitude of this parameter and could also investigate its dependence in temperature and deformation.

  9. Investigation of high-energy-proton effects in aluminum

    SciTech Connect

    Czajkowski, C.J.; Snead, C.L. Jr.; Todosow, M.

    1997-12-01

    Specimens of 1100 aluminum were exposed to several fluences of 23.5-GeV protons at the Brookhaven Alternating Gradient Synchrotron. Although this energy is above those currently being proposed for spallation-neutron applications, the results can be viewed as indicative of trends and other microstructural evolution with fluence that take place with high-energy proton exposures such as those associated with an increasing ratio of gas generation to dpa. TEM investigation showed significantly larger bubble size and lower density of bubbles compared with lower-energy proton results. Additional testing showed that the tensile strength increased with fluence as expected, but the microhardness decreased, a result for which an intepretation is still under investigation.

  10. Size effects on gamma radiation response of magnetic properties of barium hexaferrite powders

    SciTech Connect

    McCloy, John; Kukkadapu, Ravi; Crum, Jarrod; Johnson, Brad; Droubay, Tim

    2011-12-01

    Little is currently known about the effects of gamma-ray irradiation on oxide magnet materials. In particular, the effect of particle size on radiation susceptibility was investigated. Two commercial powders of BaFe{sub 12}O{sub 19} were thoroughly characterized, then exposed to 1 MGy of gamma radiation from a {sup 60}Co source. AC susceptibility and DC magnetometry and Moessbauer spectroscopy were performed after irradiation and compared to pre-irradiated measurements. DC magnetization and AC susceptibility decreased for both samples with the relative change of DC magnetization being larger for the micrometer-sized particles and the relative change of the AC susceptibility being larger for the nanometer-sized particles. Moessbauer spectroscopy indicated a decrease in both the hyperfine fields and in their distribution for each Fe site, particularly in the larger particle sample. Decreases in susceptibility are believed to be due to radiation-induced amorphization at the particle surfaces as well as amorphization and nucleation of new crystallites at internal crystallite boundaries, resulting in overall reduction in the particle magnetic moment. This radiation damage mechanism is different than that seen in previous studies of neutron and heavy ion irradiation of BaFe{sub 12}O{sub 19}.

  11. Investigation of genetically mediated child effects on maltreatment.

    PubMed

    Jay Schulz-Heik, R; Rhee, Soo Hyun; Silvern, Louise; Lessem, Jeffrey M; Haberstick, Brett C; Hopfer, Christian; Hewitt, John K

    2009-05-01

    Theory and empirical evidence suggest that children's genetically influenced characteristics help to shape the environments they experience, including the parenting they 'receive'. The extent of these genetically-mediated child effects on childhood maltreatment is not well known. The present study estimates the magnitude of genetically mediated child effects on maltreatment in 3,297 twins and siblings who were part of a large nationally representative sample of adolescents (ADD health). Participants in early adulthood retrospectively reported their experiences of physical and sexual maltreatment and neglect. Results are consistent with small genetically-mediated child effects on physical maltreatment and neglect, and none on sexual maltreatment, and all three forms of maltreatment are influenced mainly by idiosyncratic individual circumstances. PMID:19283463

  12. Investigation of the effects of returning electrons on klystron performance

    NASA Astrophysics Data System (ADS)

    Roybal, William Thomas

    The klystron, as part of an RF distribution system for an accelerator, is one of the most important components contributing to the cost, reliability, and longevity of the overall system. Operating cost is one of the primary concerns for klystrons. Achieving high direct current (DC) to radio frequency (RF) conversion efficiency, free of instabilities is very important. There is uncertainty concerning the effects of returning electrons within the klystron and the impact that they have on klystron performance. The effects of reverse traveling electrons on klystron performance, such as efficiency, are poorly defined. Classical and even modern klystron design avoids the consideration of return electrons, and thus the effects have not been numerically analyzed and quantified. A better understanding of the electron beam-to-RF conversion process and the effects of return electrons within the klystron output circuit is needed. Accurate klystron modeling and simulation of return electron effects are required to better understand the implications of the problem. This analysis identifies the influence that returning electrons have on the overall beam dynamics and self-consistent cavity voltages. Closer examination of the harmonic content within the reverse beam current, along with comparison to the nominal klystron design, reveals the effects that reverse flowing electrons can have on klystron performance and design. The results of this work include a description of the electron beam dynamics for a beam decelerated in the output cavity, with separation occurring between forward and reverse electrons. Varying the output parameter of the klystron causes an unexpected response in return current quantity and bunching quality, yielding periodic correlations and responses to two-stream interaction.

  13. A theoretical investigation of ground effects on USB configurations

    NASA Technical Reports Server (NTRS)

    Lan, C. E.

    1979-01-01

    A formulation predicts the variation of circulation forces and jet reaction forces in ground proximity as a function of ground height. The predicted results agree well with available experimental data. It is shown that the wing-alone theory is not capable of predicting the ground effect for USB configurations.

  14. The Effectiveness of Knowledge Networks: An Investigation of Manufacturing SMEs

    ERIC Educational Resources Information Center

    Hughes, Tim; O'Regan, Nicholas; Sims, Martin A.

    2009-01-01

    Purpose: Although considerable attention in the extant literature has been devoted to knowledge acquisition and transfer within firms, there is a dearth of research on the effectiveness of outside sources of knowledge for technology-based small to medium-sized enterprises (SMEs). Furthermore, the majority of empirical studies in this area focus on…

  15. Hyperfine Magnetic Field Measurements in the Heusler Alloys COBALT(2)-TITANIUM-Z, COBALT(2)-MAGNESIUM-Z (z = Silicon, Germanium, and Tin) and COBALT(2)-MAGNESIUM- Gallium Using the Moessbauer Effect (me) and the Time Differential Perturbed Angular Correlation (tdpac) Techniques

    NASA Astrophysics Data System (ADS)

    Lahamer, Amer Said

    1990-01-01

    Measurements of the hyperfine magnetic field in a series of Heusler alloys were performed. The probes were in (^{119}Sn) and cadmium (^{111}Cd). These measurements were performed at the University of Cincinnati in Cincinnati, Ohio. Two techniques were used. The first technique was the Mossbauer effect, which was used to measure the hyperfine magnetic field on ^{119 }Sn in Co_2TiZ (Z = Si, Ge, and Sn), and the second technique was the Time Differential Perturbed Angular Correlation which was used to measure the hyperfine magnetic field on ^ {111}Cd in the Co_2MnZ (Z = Si, Ge, Sn, and Ga). The probes are expected to go to the Z sites of the alloys. The hyperfine magnetic field measurements on ^{119}Sn in Co _2TiZ (Z = Si, Ge, and Sn) alloys were done at room, dry ice and liquid nitrogen temperatures by using the Mossbauer effect technique. The data were fitted by using a least squares fit from which three parameters were extracted. These parameters are the isomer shift, the quadrupole splitting and the hyperfine magnetic field. Temperature variation measurements of the hyperfine magnetic field were performed on ^{111 }Cd in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. The data were fitted again by using a least squares fit from which the Larmor frequency which is related to the hyperfine magnetic field was extracted. Also the Fourier Transforms were taken of the data, on the one hand to confirm the results of the least squares fit and on the other hand to look for more frequencies. Results of the Fourier Transforms show that some of the probe, ^{111}In, did go to the Co site in the Co_2MnZ (Z = Ga, Si, and Ge) alloys. The hmf on ^{111 }Cd in the Co site of these alloys is found to be 68 kOe which is consistent with the value found in the literature. Two theoretical models were examined for the trends of hyperfine magnetic field on ^{119 }Sn and ^{111}Cd in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. These are the Campbell and Blandin model and the Stearns' overlap model

  16. Pilot investigation of the hydrating effects of topical acne medications.

    PubMed

    Zhen, Yaxian; Stoudemayer, Marianne; Vamvakias, George; Kligman, Albert M

    2007-08-01

    Topical therapies are effective in managing acne vulgaris but are associated with local adverse effects such as irritation and dryness. This 4-week pilot study compared skin hydration in 36 healthy adult women randomized to treatment with 1 of 4 topical therapies: 2 different (jar and tube) clindamycin 1%/benzoyl peroxide 5% gels, sodium sulfacetamide 10% lotion, or over-the-counter (OTC) moisturizing cream. Subjects treated with OTC moisturizer or sodium sulfacetamide exhibited decreased water loss, increased water retention, similar or improved levels of skin hydration, and decreased desorption rates. In contrast, subjects treated with jar or tube clindamycin/benzoyl peroxide had increased water loss, decreased water retention, decreased hydration, and increased desorption rates. Skin dryness decreased slightly in the moisturizer group. No serious adverse events occurred. Overall, the OTC moisturizer had the best skin hydration profile. Sodium sulfacetamide demonstrated some moisturizing characteristics, and no clinically relevant differences were noted between jar and tube clindamycin/benzoyl peroxide gels. PMID:17763612

  17. Beecher as Clinical Investigator: Pain and the Placebo Effect.

    PubMed

    Benedetti, Fabrizio

    2016-01-01

    Among the many contributions by Henry Beecher to science and clinical practice, pain and the placebo effect certainly represent two of the most important aspects. On the one hand, Beecher considered the pain experience not only as arising from the peripheral injured tissues, but also as an emotional experience that is capable of modulating the nociceptive input. On the other hand, he analyzed the placebo effect at an unprecedented level for that time. His ideas sparked from his work on wounded soldiers during World War II. In spite of the unusual situation and the lack of sophisticated experimental tools on the battlefield, Beecher succeeded in putting forward several important concepts, and his ideas still pervade modern health care and research. PMID:27499483

  18. Investigating Ionic Effects Applied to Water Based Organocatalysed Aldol Reactions

    PubMed Central

    Delaney, Joshua P.; Henderson, Luke C.

    2011-01-01

    Saturated aqueous solutions of various common salts were examined for their effect on aqueous aldol reactions catalysted by a highly active C2-symmetric diprolinamide organocatalyst developed in our laboratory. With respect to the aldol reaction between cyclohexanone and 4-nitrobenzaldehyde, deionised water was always a superior medium to salt solutions though some correlation to increasing anion size and depression in enantiomeric excess could be observed. Additionally, the complete inhibition of catalyst activity observed when employing tap water could be alleviated by the inclusion of ethylenediaminetetraacetate (EDTA) into the aqueous media prior to reaction initiation. Extension of these reaction conditions demonstrated that these ionic effects vary on a case-to-case basis depending on the ketone/aldehyde combination. PMID:22272120

  19. An electrophysiological investigation of early effects of masked morphological priming

    PubMed Central

    Morris, Joanna; Grainger, Jonathan; Holcomb, Phillip J.

    2009-01-01

    This experiment examined event-related responses to targets preceded by semantically transparent morphologically related primes (e.g., farmer-farm), semantically opaque primes with an apparent morphological relation (cornercorn), and orthographically, but not morphologically, related primes (scandalscan) using the masked priming technique combined with a semantic categorisation task. In order to provide information about possible early effects of morphology we focused our analysis on the N250 ERP component. Priming effects for transparent and opaque items patterned together in the early phase of the N250 (200-250 ms), whereas the transparent and orthographic items patterned together in the latter phase of this component (250-300 ms). These results provide further evidence in support of the rapid extraction of morphemes from morphologically complex stimuli independently of the semantic relatedness of the whole and its parts. PMID:19779574

  20. Investigating dissipation in the quantum anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Fox, Eli; Bestwick, Andrew; Goldhaber-Gordon, David; Feng, Yang; Ou, Yunbo; He, Ke; Wang, Yayu; Xue, Qi-Kun; Kou, Xufeng; Pan, Lei; Wang, Kang

    In the quantum anomalous Hall effect, a magnetic exchange gap in a 3D topological insulator gives rise to dissipationless chiral edge states. Though the effect has recently been realized in a family of ferromagnetically-doped (Bi,Sb)2Te3 topological insulator thin films, experiments to date have found non-vanishing longitudinal resistance, contrary to initial theoretical expectations. Proposed sources of this dissipation include extra gapless or activated quasi-helical edge states, thermally activated 2D conduction, and variable-range hopping. Here, we discuss transport measurements of Corbino disk and non-local geometries to identify the mechanism of non-ideal behavior. This work supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. 19-7503.

  1. Investigation of polarization effects on new mask materials

    NASA Astrophysics Data System (ADS)

    Bubke, Karsten; Teuber, Silvio; Hoellein, Ingo; Becker, Hans; Seitz, Holger; Buttgereit, Ute

    2005-05-01

    As microlithography moves to smaller critical dimensions, structures on reticles reach feature sizes comparable to the operating wavelength. Furthermore, with increasing NA the angle of incidence of light illuminating the mask steadily increases. In particular for immersion lithography this will have severe consequences on the printing behavior of reticles. Polarization effects arise which have an impact on, among other things, the contrast of the printed image. Angular effects have to be considered when aggressive off-axis illumination schemes are used. Whereas numerous articles have been published on those effects and the underlying theory seems to be understood, there is a strong need for experimental verification of properties of real masks at the actinic wavelength. This paper presents measurements of polarization effects on different mask blank types produced at Schott Lithotec including chrome and alternative absorber binary mask blanks, as well as phase shift mask blanks. Thickness and optical dispersion of all layers were determined using grazing incidence x-ray reflectometry (GIXR) and variable angle spectroscopic ellipsometry (VASE). The set of mask blanks was patterned using a special design developed at the Advanced Mask Technology Center (AMTC) to allow measurements at different line width and pitch sizes. VUV Ellipsometry was then used to measure the properties of the structured materials, in particular the intensities in the 0th and 1st diffraction order for both polarization directions and varying angle of incidence. The degree of polarization of respective mask types is evaluated for dense lines with varying pitches and duty cycles. The results obtained experimentally are compared with simulations based on rigorous coupled wave analysis (RCWA).

  2. Numerical Investigation of Angulation Effects in Stenosed Renal Arteries

    PubMed Central

    Mortazavinia, Z; Arabi, S; Mehdizadeh, A R

    2014-01-01

    Background: Numerical study of angulation effects of renal arteries on blood flow has been of great interest for many researchers. Objective: This paper aims at numerically determining the angulation effects of stenosed renal arteries on blood flow velocity and renal mass flow. Method: An anatomically realistic model of abdominal aorta and renal arteries is reconstructed from CT-scan images and used to conduct numerical simulation of pulsatile non-Newtonian blood flow incorporating fluid-structure interaction. The renal arteries in the realistic model have left and right branch angles of 53˚ and 45˚, respectively. Atrapezium shape stenosis is considered in the entrance of right renal artery. Two other branch angles, i.e. 90 and 135˚, are also considered for right renal artery to study the angulation effects. Results: Comparison between models with right renal branch angles of 45˚, 90˚ and 135˚ reveals that high curvature of streamlines in the entrance of the renal artery with the angle of 135˚ causes the flow velocity and renal mass flow to be less than those of 45˚and 90˚. Conclusion: It is concluded that large renal branch angles cause the arteries to be unable to deliver blood in the requisite amounts to kidney. Kidney responds to counteract low blood flow by activating the renin-angiotension system which leads to severe hypertension. PMID:25505762

  3. Investigation of spherical aberration effects on coherent lidar performance.

    PubMed

    Hu, Qi; Rodrigo, Peter John; Iversen, Theis F Q; Pedersen, Christian

    2013-11-01

    In this paper we demonstrate experimentally the performance of a monostatic coherent lidar system under the influence of phase aberrations, especially the typically predominant spherical aberration (SA). The performance is evaluated by probing the spatial weighting function of the lidar system with different telescope configurations using a hard target. It is experimentally and numerically proven that the SA has a significant impact on lidar antenna efficiency and optimal beam truncation ratio. Furthermore, we demonstrate that both effective probing range and spatial resolution of the system are substantially influenced by SA and beam truncation. PMID:24216792

  4. Computational Investigation of Quantum Size Effects in Gold Nanoparticles

    SciTech Connect

    2010-01-01

    Electron density perturbation from carbon monoxide adsorption on a multi-hundred atom gold nanoparticle. The perturbation causes significant quantum size effects in CO catalysis on gold particles. Science: Jeff Greeley and Nick Romero, Argonne National Laboratory; Jesper Kleis, Karsten Jacobsen, Jens Nørskov, Technical University of Denmark
 Visualization: Joseph Insley, Argonne National Laboratory This research used resources of the Argonne Leadership Computing Facility at Argonne National Laboratory, which is supported by the Office of Science of the U.S. Dept. of Energy under contract DE-AC02-06CH11357.

  5. [Investigation of subalin effect on urogenital microflora of pregnant women].

    PubMed

    Sirokvasha, E A; Paran'ko, S I; Kozitskaia, S N; Vinnikov, A I

    2002-01-01

    Bacteriological examination of 30 women with incomplete pregnancy has been conducted. Representatives of 18 genera of aerobic and anaerobic bacteria as well as yeast-like fungi of Candida genus were found. It has been established that spore-forming bacteria of the Bacillus genus from subalin preparation have antagonistic activity in respect of the strains of pathogenic and opportunistic bacteria with characteristic zones of growth depression of 12-15 mm. This demonstrates that the agents of infectional urogenital process are effectively suppressed by subalin. PMID:11944342

  6. Investigation of land use effects on Nash model parameters

    NASA Astrophysics Data System (ADS)

    Niazi, Faegheh; Fakheri Fard, Ahmad; Nourani, Vahid; Goodrich, David; Gupta, Hoshin

    2015-04-01

    Flood forecasting is of great importance in hydrologic planning, hydraulic structure design, water resources management and sustainable designs like flood control and management. Nash's instantaneous unit hydrograph is frequently used for simulating hydrological response in natural watersheds. Urban hydrology is gaining more attention due to population increases and associated construction escalation. Rapid development of urban areas affects the hydrologic processes of watersheds by decreasing soil permeability, flood base flow, lag time and increase in flood volume, peak runoff rates and flood frequency. In this study the influence of urbanization on the significant parameters of the Nash model have been investigated. These parameters were calculated using three popular methods (i.e. moment, root mean square error and random sampling data generation), in a small watershed consisting of one natural sub-watershed which drains into a residentially developed sub-watershed in the city of Sierra Vista, Arizona. The results indicated that for all three methods, the lag time, which is product of Nash parameters "K" and "n", in the natural sub-watershed is greater than the developed one. This logically implies more storage and/or attenuation in the natural sub-watershed. The median K and n parameters derived from the three methods using calibration events were tested via a set of verification events. The results indicated that all the three method have acceptable accuracy in hydrograph simulation. The CDF curves and histograms of the parameters clearly show the difference of the Nash parameter values between the natural and developed sub-watersheds. Some specific upper and lower percentile values of the median of the generated parameters (i.e. 10, 20 and 30 %) were analyzed to future investigates the derived parameters. The model was sensitive to variations in the value of the uncertain K and n parameter. Changes in n are smaller than K in both sub-watersheds indicating

  7. Experimental Investigation of Rotorcraft Outwash in Ground Effect

    NASA Technical Reports Server (NTRS)

    Tanner, Philip E.; Overmeyer, Austin D.; Jenkins, Luther N.; Yao, Chung-Sheng; Bartram, Scott M.

    2015-01-01

    The wake characteristics of a rotorcraft are affected by the proximity of a rotor to the ground surface, especially during hover. Ground effect is encountered when the rotor disk is within a distance of a few rotor radii above the ground surface and results in an increase in thrust for a given power relative to that same power condition with the rotor out of ground effect. Although this phenomenon has been highly documented and observed since the beginning of the helicopter age, there is still a relatively little amount of flow-field data existing to help understand its features. Joint Army and NASA testing was conducted at NASA Langley Research Center using a powered rotorcraft model in hover at various rotor heights and thrust conditions in order to contribute to the complete outwash data set. The measured data included outwash velocities and directions, rotor loads, fuselage loads, and ground pressures. The researchers observed a linear relationship between rotor height and percent download on the fuselage, peak mean outwash velocities occurring at radial stations between 1.7 and 1.8 r/R regardless of rotor height, and the measurement azimuthal dependence of the outwash profile for a model incorporating a fuselage. Comparisons to phase-locked PIV data showed similar contours but a more contracted wake boundary for the PIV data. This paper describes the test setup and presents some of the averaged results.

  8. Postbuckling Investigations of Piezoelectric Microdevices Considering Damage Effects

    PubMed Central

    Sun, Zhigang; Wang, Xianqiao

    2014-01-01

    Piezoelectric material has been emerging as a popular building block in MEMS devices owing to its unique mechanical and electrical material properties. However, the reliability of MEMS devices under buckling deformation environments remains elusive and needs to be further explored. Based on the Talreja's tensor valued internal state damage variables as well as the Helmhotlz free energy of piezoelectric material, a constitutive model of piezoelectric materials with damage is presented. The Kachanvo damage evolution law under in-plane compressive loads is employed. The model is applied to the specific case of the postbuckling analysis of the piezoelectric plate with damage. Then, adopting von Karman's plate theory, the nonlinear governing equations of the piezoelectric plates with initial geometric deflection including damage effects under in-plane compressive loads are established. By using the finite difference method and the Newmark scheme, the damage evolution for damage accumulation is developed and the finite difference procedure for postbuckling equilibrium path is simultaneously employed. Numerical results show the postbuckling behaviors of initial flat and deflected piezoelectric plates with damage or no damage under different sets of electrical loading conditions. The effects of applied voltage, aspect ratio of plate, thick-span ratio of plate, damage as well as initial geometric deflections on the postbuckling behaviors of the piezoelectric plate are discussed. PMID:24618774

  9. Investigation of Isotope Effects in Single Ion Reactions

    NASA Astrophysics Data System (ADS)

    Goeders, James; Clark, Craig; Khanyile, Ncamiso; Brown, Kenneth

    2011-05-01

    Cold molecular ions are of great interest for studying chemical reactions. At the ultralow temperatures achievable using laser cooling techniques, chemical reactions are dominated by quantum effects not generally observed at higher temperatures. Studying reactions at these low temperatures allows for probing of the reaction mechanisms and the topology of potential energy surfaces, providing tests of ab initio and reactive- scattering calculations. Many chemical reactions are dominated by isotope effects. Ion beam studies have looked at reactions of alkaline earth ions with HD and observed different patterns of reactivity between Period 2 and Period 3 elements. Magnesium was shown to have a larger reaction cross-section for forming MgD+ than MgH+ by a factor of 2 - 4. Single ion experiments involving reactions between Mg+ in the 3p2P3/2 excited state and HD, utilizing trapped atomic ions, were done by Staanum et al., showing a branching ratio on the order of the results seen in the beam studies. Ion beam experiments have also been done on ground-state 40Ca+ with HD. In those experiments, the ratio of formation of CaH+ to CaD+ was observed to be ~4, opposite and in stark contrast to the magnesium ratio. The current work compares single atomic calcium ion data with molecular beam data, looking at both the 4p2P3/2 and the 4p2P1/2 excited states, similar to the work done with Mg+.

  10. Investigation on Health Effects of an Abandoned Metal Mine

    PubMed Central

    Kim, Soyeon; Cheong, Hae-Kwan; Choi, Kyungho; Jang, Jae-Yeon; Jeong, Woo-Chul; Kim, Dae-Seon; Yu, Seungdo; Kim, Young-Wook; Lee, Kwang-Young; Yang, Seoung-Oh; Jhung, Ik Jae; Yang, Won-Ho; Hong, Yun-Chul

    2008-01-01

    To investigate potential health risks associated with exposure to metals from an abandoned metal mine, the authors studied people living near an abandoned mine (n=102) and control groups (n=149). Levels of cadmium, copper, arsenic, lead, and zinc were measured in the air, soil, drinking water, and agricultural products. To assess individual exposure, biomarkers of each metal in blood and urine were measured. β2-microglobulin, α1-microglobulin, and N-acetyl-beta-glucosaminidase and bone mineral density were measured. Surface soil in the study area showed 2-10 times higher levels of metals compared to that of the control area. Metal concentrations in the groundwater and air did not show any notable differences between groups. Mean concentrations of cadmium and copper in rice and barley from the study area were significantly higher than those of the control area (p<0.05). Geometric means of blood and urine cadmium in the study area were 2.9 µg/L and 1.5 µg/g Cr, respectively, significantly higher than those in the control area (p<0.05). There were no differences in the levels of urinary markers of early kidney dysfunction and bone mineral density. The authors conclude that the residents near the abandoned mine were exposed to higher levels of metals through various routes. PMID:18583882

  11. Investigation of hierarchical structure formation in ceramics with invar effect

    NASA Astrophysics Data System (ADS)

    Dedova, Elena S.; Shadrin, Vladimir S.; Shutilova, Ekaterina S.; Kulkov, Sergei N.

    2015-10-01

    The structure, phase composition and thermal properties of (Al2O3-20 wt % ZrO2)-ZrW2O8 ceramic composites obtained using nanosized, finely dispersed and coarse-grained initial powders were investigated. On the polished surface of composites homogeneously distributed white particles were observed. The chemical composition of the particles was determined. The phase composition of the composites was represented with corundum, monoclinic ZrO2 and two modifications of ZrW2O8 (tetragonal and cubic) regardless of initial powders morphology. Crystal structure parameters of the material obtained were determined. Linear thermal expansion coefficient values of the composites were determined and compared with those calculated using the mixture rule. The experimental data correlated well with the calculated values of CTE for Al2O3-20 wt % ZrO2 ceramics. The difference in thermal expansion values for composites obtained using initial components with different morphology may be attributed to phase transformations, features of hierarchical structures, internal stresses due to thermal expansion mismatch, which contribute significantly to thermal expansion of the ceramic composites.

  12. Investigation of Scaling Effects on Fish Pectoral Fin Performance

    NASA Astrophysics Data System (ADS)

    Bozkurttas, Meliha; Dong, Haibo; Mittal, Rajat; Madden, Peter; Lauder, George

    2006-11-01

    Reynolds and Strouhal numbers are two key parameters that can potentially affect the performance of rigid and deformable flapping foils. Flow past a deformable pectoral fin of a fish in steady forward motion (speed of 1 BL/s) is simulated using a Cartesian grid immersed boundary solver. Investigation of the scaling of the performance with these two parameters allows us to gain better insight into the fundamental mechanisms of the thrust production as well as address the practical question of how the performance of a fin is expected to change with changes in size, speed and frequency. It is found that the essential fluid dynamic mechanisms are unchanged with Reynolds number. We observe that although the vortex structures get more complicated with increasing Re, the key features (like the strong tip vortex, leading and trailing edge vortices) are similar in all the cases. On the other hand, the hydrodynamic performance of the fin is found to be quite sensitive to the Strouhal number. A set of numerical simulations of fin gaits synthesized from the POD modes are also carried out. This approach allows us to connect specific features in the fin gait with the observed vortex dynamics and hydrodynamic force production.

  13. Quantifying wildfires exposure for investigating health-related effects

    NASA Astrophysics Data System (ADS)

    Youssouf, H.; Liousse, C.; Roblou, L.; Assamoi, E. M.; Salonen, R. O.; Maesano, C.; Banerjee, S.; Annesi-Maesano, I.

    2014-11-01

    A wildfire is an uncontrolled fire in an area of combustible vegetation that occurs in the countryside or a wilderness area. The United Nation International Strategy for Disaster Reduction estimates that between 3 and 4 million km2 are affected by wildfire annually, with 18 000 km2 occurring in Europe. The Mediterranean region is one of the most affected regions by wildfires in Europe. Nearly 500 000 ha, on average, are burned annually by 50 000 wildfires in the countries of southern Europe bordering the Mediterranean Sea. Wildfires or biomass burning seriously damage ecosystems and affect public health. A major difficulty related to the assessment of health impact of wildfire emissions derives from the complexity of wildfire exposure assessments. Based on the literature, several methods, including satellite data, chemical transport models and, less often, personal exposure monitoring are available. However, few investigations have used methods allowing separating wildfires emissions from air pollutants emissions from urban sources having the same components. An inventory of wildfires occurred in Europe between 2006 and 2010 was obtained in terms of burnt areas, duration and related emissions of major air pollutants (black carbon, particulate matter), as obtained using a hybrid model that allows excluding anthropic sources of air pollution.

  14. Experimental investigation of the evacuation effect in expansion deflection nozzles

    NASA Astrophysics Data System (ADS)

    Taylor, N. V.; Hempsell, C. M.; Macfarlane, J.; Osborne, R.; Varvill, R.; Bond, A.; Feast, S.

    2010-02-01

    This paper provides an overview of results generated by the static test expansion-deflection rocket nozzle (STERN) project. The engine propellants were gaseous air and hydrogen, with a design chamber pressure and thrust of 102 bar and 5 kN respectively. The maximum chamber pressure achieved was restricted to 55 bar absolute, due to a conservative approach in the test programme dictated by the uncertainty in heat transfer to the pintle. Despite this, the programme achieved many successes, including the first tests of an ED nozzle in the UK; the production of significant amounts of data for both the analysis of the performance of the nozzle and the verification of analysis codes; and an improved compensation performance over that apparent from earlier work, including demonstration of attached flow to the exit plane for all chamber pressures. Whilst the wake pressure was not as high as hoped, ranging between 70% and 95% of ambient and apparently inversely related to chamber pressure, this result is still sufficiently encouraging to warrant further investigation of the type. As importantly, the data derived from the experiments, including performance analysis and wall pressure variations in time and space, are now being made available to the wider academic community, something which for commercial reasons appears to be a unique occurrence for this type of nozzle.

  15. Investigating effects of communications modulation technique on targeting performance

    NASA Astrophysics Data System (ADS)

    Blasch, Erik; Eusebio, Gerald; Huling, Edward

    2006-05-01

    One of the key challenges facing the global war on terrorism (GWOT) and urban operations is the increased need for rapid and diverse information from distributed sources. For users to get adequate information on target types and movements, they would need reliable data. In order to facilitate reliable computational intelligence, we seek to explore the communication modulation tradeoffs affecting information distribution and accumulation. In this analysis, we explore the modulation techniques of Orthogonal Frequency Division Multiplexing (OFDM), Direct Sequence Spread Spectrum (DSSS), and statistical time-division multiple access (TDMA) as a function of the bit error rate and jitter that affect targeting performance. In the analysis, we simulate a Link 16 with a simple bandpass frequency shift keying (PSK) technique using different Signal-to-Noise ratios. The communications transfer delay and accuracy tradeoffs are assessed as to the effects incurred in targeting performance.

  16. Investigation into the effect of transformer oil on polymers

    SciTech Connect

    Frost, N.E.; McGrath, P.B.; Burns, C.W.

    1996-01-01

    Several thermoplastics and an epoxy were exposed to a variety of conditions to determine the effect of chemical environment on the materials. Weight gain measurements of the samples were made after exposure to low humidity, ambient air, 90 C air, ambient transformer oil, and 90 C transformer oil. Two materials that performed well in these tests were polyetherimide (Ultem) and amine cured bisphenol-A epoxy. It was found that Noryl, a thermoplastic combination of high impact polystyrene and polyphenyleneoxide, was unsuitable for use in transformer oil, as it suffered substantial physical degradation. Polystyrene and high impact polystyrene (rubber modified polystyrene) performed poorly in both ambient and 90{degree} transformer oil tests, with the rubber modified material exhibiting a much greater weight gain. Both high and low density polyethylene also showed large weight gains in hot transformer oil.

  17. Investigation of spatial misregistration effects in multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Nalepka, R. F. (Principal Investigator); Malila, W. A.; Gleason, J. M.; Cicone, R. C.

    1976-01-01

    The author has identified the following significant results. A model for estimating the expected proportion of multiclass pixels in a scene was generalized and extended to include misregistration effects. Another substantial effort was the development of a simulation model to generate signatures to represent the distributions of signals from misregistered multiclass pixels, based on single class signatures. Spatial misregistration causes an increase in the proportion of multiclass pixels in a scene and a decorrelation between signals in misregistered data channels. The multiclass pixel proportion estimation model indicated that this proportion is strongly dependent on the pixel perimeter and on the ratio of the total perimeter of the fields in the scene to the area of the scene. Test results indicated that expected values computed with this model were similar to empirical measurements made of this proportion in four LACIE data segments.

  18. Experimental investigation and modeling of scale effects in jet ejectors

    NASA Astrophysics Data System (ADS)

    Gardner, W. G.; Wang, I.; Jaworski, J. W.; Brikner, N. A.; Protz, J. M.

    2010-08-01

    Three microscale jet ejectors were designed and tested to induce a suction draft using a supersonic micronozzle. Each axisymmetric nozzle was fabricated using three-dimensional electro-discharge machining to create throat diameters of 64, 187 and 733 µm with design expansion ratios of 2.5:1 and design ejector area ratios of 8. The experimental data using nitrogen gas for the motive fluid indicate that the ejector can produce a sufficient suction draft to enable its substitution for high-speed turbomachinery in micro engine applications. A pumping power density of 308 kW L-1 is observed experimentally, which agrees well with a theoretical model including losses associated with the suction flow inlet and viscous effects in the motive nozzle and mixing regions. The present theoretical model further predicts a maximum achievable power density of 1 MW L-1 for microscale ejectors with a throat diameter of 10 µm and throat Reynolds number of 1300.

  19. Omnify: Investigating the Visibility and Effectiveness of Copyright Monitors

    NASA Astrophysics Data System (ADS)

    Potharaju, Rahul; Seibert, Jeff; Fahmy, Sonia; Nita-Rotaru, Cristina

    The arms race between copyright agencies and P2P users is an ongoing and evolving struggle. On the one hand, content providers are using several techniques to stealthily find unauthorized distribution of copyrighted work in order to deal with the problem of Internet piracy. On the other hand, P2P users are relying increasingly on blacklists and anonymization methods in order to avoid detection. In this work, we propose a number of techniques to reveal copyright monitors' current approaches and evaluate their effectiveness. We apply these techniques on data we collected from more than 2.75 million BitTorrent swarms containing 71 million IP addresses. We provide strong evidence that certain nodes are indeed copyright monitors, show that monitoring is a world-wide phenomenon, and devise a methodology for generating blacklists for paranoid and conservative P2P users.

  20. Building Effective Scientist-Teacher Partnerships: A Case Study Investigation

    NASA Astrophysics Data System (ADS)

    Walker, B. A.; Hall, M. K.; Regens, N. L.

    2005-12-01

    Scientist-teacher partnerships provide opportunities for scientists to become better educators and teachers to increase their science content knowledge, but few accounts exist about how partnerships evolve and why some succeed and others fail. We investigated these questions in the context of an NSF GK-12 program that pairs graduate and undergraduate science and math students (fellows) with K-12 teachers. Using a variety of data sources, we found several patterns that were influential across the majority of partnerships. Aligned, partnership-centered goals and expectations were most conducive to productive relationships. A desire and commitment to collaborate and a willingness to communicate openly were also essential. Differences in the rigidity and intensity of the K-12 and university schedules and working with multiple teachers made collaboration difficult due to lack of planning time. Mutual investment manifested itself in several ways among partnerships including collaboration on teaching, planning, and other classroom activities, exchange of resources, and exchange of constructive feedback. Fellows and teachers were most likely to invest themselves when they perceived that their contributions were invited and appreciated in and out of the classroom. In all cases, role ambiguity was a major barrier to partnership formation. Fellows employed numerous strategies to define their roles, but working collaboratively was possible only when roles were discussed and allowed to evolve. Fellows and teachers found it difficult to communicate directly about dissatisfaction. While each partnership was unique, these major patterns influencing the success of a partnership occur in many situations and thus appear transferable. Regardless of outcome, partners felt as though they benefited significantly from this experience. Our results may be applied to similar partnership programs to improve project design and enhance the sustainability of relationships between scientists and

  1. Investigation of drift effect on silicon nanowire field effect transistor based pH sensor

    NASA Astrophysics Data System (ADS)

    Kim, Sihyun; Kwon, Dae Woong; Lee, Ryoongbin; Kim, Dae Hwan; Park, Byung-Gook

    2016-06-01

    It is widely accepted that the operation mechanism of pH-sensitive ion sensitive field effect transistor (ISFET) can be divided into three categories; reaction of surface sites, chemical modification of insulator surface, and ionic diffusion into the bulk of insulator. The first mechanism is considered as the main operation mechanism of pH sensors due to fast response, while the others with relatively slow responses disturb accurate pH detection. In this study, the slow responses (often called drift effects) are investigated in silicon nanowire (SiNW) pH-sensitive ISFETs. Based on the dependence on the channel type of SiNW, liquid gate bias, and pH, it is clearly revealed that the drift of n-type SiNW results from H+ diffusion into the insulator whereas that of p-type SiNW is caused by chemical modification (hydration) of the insulator.

  2. Moessbauer and magnetic study of Mn, Zr and Cd substituted W-type hexaferrites prepared by co-precipitation

    SciTech Connect

    Iqbal, Muhammad Javed; Khan, Rafaqat Ali; Mizukami, Shigemi; Miyazaki, Terunobu

    2011-11-15

    Highlights: {yields} Zr and Cd ions substitute tetrahedral 4e and 4f{sub IV} sites while Mn ions occupy octahedral 6g and 4f sites. {yields} Doping of W-type hexaferrites with Mn, Zr and Cd improves the values of M{sub s} and M{sub r}. {yields} The enhancement of magnetic characteristic togetherwith the formation of rice shaped W-type hexaferrites nanoparticles is promising for imaging and sensing devices. {yields} The synthesized materials are suitable for magnetic data storage with high density. -- Abstract: BaCo{sub 2-x}Mn{sub x}Fe{sub 16-2y}(Zr-Cd){sub y}O{sub 27} (x = 0-0.5 and y = 0-1.0) hexaferrite nanocrystallites of average sizes in the range of 33-42 nm are synthesized by the chemical co-precipitation method. The synthesized materials are characterized using different techniques including X-ray diffraction (XRD), energy dispersive X-ray florescence (ED-XRF), scanning electron microscope (SEM), Moessbauer spectrometer and vibrating-sample magnetometer (VSM). Based on analysis of the data obtained from Moessbauer spectral studies, doping is believed to have occurred preferably in the vicinity of 12k sub-lattice, i.e. f{sub IV} (4e, 4f{sub IV}), 2b (6g, 4f) and 2d site. Variations in the saturation magnetization (77.1-60.9 emu g{sup -1}), remanent magnetization (22.08-31.23 emu g{sup -1}) and coercivity (1570.1-674.7 Oe) exhibit tunable behavior with dopant content and therefore can be useful for application in various magnetic devices.

  3. Investigation Into The Effectiveness of The JLAB High Pressure Rinse System

    SciTech Connect

    John Mammosser; Timothy Rothgeb; Tong Wang; Andy Wu

    2003-05-01

    As part of a study to reduce field emission in Superconducting radio frequency cavities, an investigation into the effectiveness of the Jefferson Lab's High Pressure Rinse (HPR) system is underway. This paper describes discoveries from this investigation, the procedural changes made during this investigation, current vertical test results and further plans for improvements and monitoring.

  4. Attention when?: An Investigation of the Ordering Effect of Input and Interaction

    ERIC Educational Resources Information Center

    Gass, Susan M.; Torres, Maria Jose Alvarez

    2005-01-01

    This paper investigates the effects of input and interaction as separate entities and in combination. We further investigate these effects as a function of different language areas. One hundred two learners of L2 Spanish were provided with input on (a) Spanish gender agreement (noun + adjective), (b) "estar" + location, and (c) seven vocabulary…

  5. Investigating the Interplay between Semantic and Phonological Distractor Effects in Picture Naming

    ERIC Educational Resources Information Center

    Melinger, Alissa; Rahman, Rasha Abdel

    2004-01-01

    In this paper, we investigate the interplay between phonological facilitation and semantic interference effects in picture naming. We use a double distractor variant of the classic picture-word interference paradigm to investigate whether the reported interaction between these effects is dependent on the two types of related information being…

  6. Numerical investigation of the effect of sphere dimples on the drag crisis and the Magnus effect

    NASA Astrophysics Data System (ADS)

    Li, Jing; Tsubokura, Makoto; Tsunoda, Masaya

    2015-11-01

    The present study investigates the flow over a golf ball and a smooth sphere around the critical Reynolds numbers under both stationary and self-spinning conditions by conducting Large-eddy simulations (LES) based on high resolution unstructured grids. For the stationary cases, the present calculation results validate the promotion of the drag crisis at a relatively lower Reynolds number due to the golf ball dimples. It also shows that the golf ball dimples have a limited effect on the time-dependent lateral force development in the subcritical regime, whereas the dimples are beneficial in suppressing the lateral force oscillations in the supercritical regimes. With spin parameter Γ = 0.1, the drag coefficients for the spinning smooth sphere increase slightly in all Reynolds number regimes when compared to the stationary cases, whereas for the spinning golf ball, the drag force decreases in the critical regime and increases in the supercritical regime. For both spinning models, the inverse Magnus effect was reproduced in the critical regime, whereas in the supercritical regime the ordinary Magnus force was generated. Relatively weaker lift forces were also observed in the cases of the spinning golf balls when compared to the spinning smooth spheres.

  7. {sup 151}Eu and {sup 121}Sb Moessbauer spectroscopy of EuSbSe{sub 3} and EuBiSe{sub 3}

    SciTech Connect

    Schappacher, Falko M.; Poettgen, Rainer Bang Jin, Geng; Albrecht-Schmitt, Thomas E.

    2007-11-15

    {sup 151}Eu and {sup 121}Sb Moessbauer spectroscopy of EuSbSe{sub 3} and EuBiSe{sub 3} were measured at different temperatures. The presence of divalent europium and trivalent antimony were confirmed. The largely negative values of the isomer shift in {sup 151}Eu spectrum show highly ionic bonding within these two compounds. Both of them show magnetic hyperfine field splitting at 4.2 K, which indicates a change in the orientation of the EFG principal axis with respect to the magnetic hyperfine field direction. EuSbSe{sub 3} has slightly smaller electron density at the antimony nuclei, compared to Sb{sub 2}Se{sub 3.} - Graphical abstract: Experimental and simulated {sup 121}Sb Moessbauer spectrum of EuSbSe{sub 3} at 77 K.

  8. Elasticity and magnetocaloric effect in MnFe4Si3

    DOE PAGESBeta

    Herlitschke, Marcus; Klobes, B.; Sergueev, I.; Hering, Paul; Persson, Joerg; Hermann, Raphael P.

    2016-03-16

    The room temperature magnetocaloric material MnFe4Si3 was investigated with nuclear inelastic scattering (NIS) and resonant ultrasound spectroscopy (RUS) at different temperatures and applied magnetic fields in order to assess the infuence of the magnetic transition and the magnetocaloric effect on the lattice dynamics. The NIS data give access to phonons with energies above 3 meV, whereas RUS probes the elasticity of the material in the MHz frequency range and thus low energy, ~5 neV, phonon modes. A significant infuence of the magnetic transition on the lattice dynamics is observed only in the low energy region. Here, MnFe4Si3 and other compoundsmore » in the Mn5-xFexSi3 series were also investigated with vibrating sample magnetometry, resistivity measurements and Moessbauer spectroscopy in order to study the magnetic transitions and to complement the obtained results on the lattice dynamics.« less

  9. Investigating the Effects of Planning on L2 Text Chat Performance

    ERIC Educational Resources Information Center

    Hsu, Hsiu-Chen

    2012-01-01

    Over the last decade, a small body of SLA research has examined the effects of task planning on L2 production. This research has revealed positive results concerning the effect of pre-task and online planning on oral and written production. However, no studies to date have investigated the joint effects of pre-task and online planning. In…

  10. Investigating the Causal Association between Unionism and Organizational Effectiveness. Revised. ASHE 1984 Annual Meeting Paper.

    ERIC Educational Resources Information Center

    Cameron, Kim S.

    Assessments of organizational effectiveness in a sample of four-year institutions in 1976, 1980, and 1983 were used to investigate the potential causal directionality of unionism and organizational effectiveness. Nine dimensions of effectiveness were analyzed: student educational satisfaction, student academic development, student career…

  11. Investigation of Post-mortem Tissue Effects Using Long-time Decorrelation Ultrasound

    NASA Astrophysics Data System (ADS)

    Csány, Gergely; Balogh, Lajos; Gyöngy, Miklós

    Decorrelation ultrasound is being increasingly used to investigate long-term biological phenomena. In the current work, ultrasound image sequences of mice who did not survive anesthesia (in a separate investigation) were analyzed and post-mortem tissue effects were observed via decorrelation calculation. A method was developed to obtain a quantitative parameter characterizing the rate of decorrelation. The results show that ultrasound decorrelation imaging is an effective method of observing post-mortem tissue effects and point to further studies elucidating the mechanism behind these effects.

  12. The Effect of Lake Erie on Ohio's Temperature, Student Guide and Teacher Guide. OEAGLS Investigation 1.

    ERIC Educational Resources Information Center

    Meinke, James D.; Kennedy, Beth A.

    This guidebook for teachers is accompanied by a student workbook. The investigations are intended to offer students an opportunity to learn about the absorption and release of heat energy and its effects on the Earth's atmosphere. The influence of Lake Erie on Ohio's temperature is related to the other investigations. Illustrations, maps, and…

  13. An Investigation into the Effectiveness of Problem-Based Learning in a Physical Chemistry Laboratory Course

    ERIC Educational Resources Information Center

    Gurses, Ahmet; Acikyildiz, Metin; Dogar, Cetin; Sozbilir, Mustafa

    2007-01-01

    The aim of this study was to investigate the effectiveness of a problem-based learning (PBL) approach in a physical chemistry laboratory course. The parameters investigated were students' attitudes towards a chemistry laboratory course, scientific process skills of students and their academic achievement. The design of the study was one group…

  14. Ditching Investigations of Dynamic Models and Effects of Design Parameters on Ditching Characteristics

    NASA Technical Reports Server (NTRS)

    Fisher, Lloyd J; Hoffman, Edward L

    1958-01-01

    Data from ditching investigations conducted at the Langley Aeronautical Laboratory with dynamic scale models of various airplanes are presented in the form of tables. The effects of design parameters on the ditching characteristics of airplanes, based on scale-model investigations and on reports of full-scale ditchings, are discussed. Various ditching aids are also discussed as a means of improving ditching behavior.

  15. EuTZn (T=Pd, Pt, Au) with TiNiSi-type structure-Magnetic properties and {sup 151}Eu Moessbauer spectroscopy

    SciTech Connect

    Mishra, Trinath; Hermes, Wilfried; Harmening, Thomas; Eul, Matthias; Poettgen, Rainer

    2009-09-15

    The europium compounds EuTZn (T=Pd, Pt, Au) were synthesized from the elements in sealed tantalum tubes in an induction furnace. These intermetallics crystallize with the orthorhombic TiNiSi-type structure, space group Pnma. The structures were investigated by X-ray diffraction on powders and single crystals: a=732.3(2), b=448.5(2), c=787.7(2) pm, R{sub 1}/wR{sub 2}=0.0400/0.0594, 565 F{sup 2} values for EuPdZn, a=727.8(3), b=443.7(1), c=781.7(3) pm, R{sub 1}/wR{sub 2}=0.0605/0.0866, 573 F{sup 2} values for EuPtZn, and a=747.4(2), b=465.8(2), c=789.1(4) pm, R{sub 1}/wR{sub 2}=0.0351/0.0590, 658 F{sup 2} values for EuAuZn, with 20 variables per refinement. Together the T and zinc atoms build up three-dimensional [TZn] networks with short T-Zn distances. The EuTZn compounds show Curie-Weiss behavior in the temperature range from 75 to 300 K with mu{sub eff}=7.97(1), 7.70(1), and 7.94(1) mu{sub B}/Eu atom and theta{sub P}=18.6(1), 34.9(1), and 55.5(1) K for T=Pd, Pt, and Au, respectively, indicating divalent europium. Antiferromagntic ordering was detected at 15.1(3) K for EuPdZn and canted ferromagnetic ordering at 21.2(3) and 51.1(3) K for EuPtZn and EuAuZn. {sup 151}Eu Moessbauer spectroscopic measurements confirm the divalent nature of the europium atoms by isomer shift values ranging from -8.22(8) (EuPtZn) to -9.23(2) mm/s (EuAuZn). At 4.2 K full magnetic hyperfine field splitting is observed in all three compounds due to magnetic ordering of the europium magnetic moments. - Graphical abstract: Europium coordination in EuPdZn, EuPtZn, and EuAuZn.

  16. Moessbauer and SEM characterization of the scale on type 304 stainless steel

    SciTech Connect

    Waanders, F.B.; Vorster, S.W.; Engelbrecht, A.

    2000-05-10

    Defects that form on stainless steels during production cause reworking, leading to higher production costs associated with production delays. Primarily wrong casting, rolling, grinding, annealing and pickling practices cause typical metallurgical defects such as the formation of residual scale. In the present investigation the problem of residual scale development on austenitic stainless steel (type AISI 304, with typical composition 19%Cr, 8%Ni, 1.5%Mn, <1%Si and the balance Fe) was investigated. Scale that is not removed during the pickling process is referred to as residual scale. Characterization of the surface scale is a prerequisite for effective measures aimed at minimizing scale formation and the design of efficient descaling procedures. The scale consists of an outer layer of iron oxides and an inner layer composed of small grains of FeCr{sub 2}O{sub 4} with the scale-metal interface not uniform and oxidation occurring along grain boundaries. Internal oxidation is found near the scale-metal interface with the amount of unoxidized metal increasing toward the scale-metal interface. If the scale is not removed from the hot steel it may be rolled into the product surface which will then require additional processing. Descaling presently used for stainless steel comprises of acid pickling, mechanical descaling and electrolytic pickling.

  17. Further Investigating Method Effects Associated with Negatively Worded Items on Self-Report Surveys

    ERIC Educational Resources Information Center

    DiStefano, Christine; Motl, Robert W.

    2006-01-01

    This article used multitrait-multimethod methodology and covariance modeling for an investigation of the presence and correlates of method effects associated with negatively worded items on the Rosenberg Self-Esteem (RSE) scale (Rosenberg, 1989) using a sample of 757 adults. Results showed that method effects associated with negative item phrasing…

  18. Investigating Strength and Frequency Effects in Recognition Memory Using Type-2 Signal Detection Theory

    ERIC Educational Resources Information Center

    Higham, Philip A.; Perfect, Timothy J.; Bruno, Davide

    2009-01-01

    Criterion- versus distribution-shift accounts of frequency and strength effects in recognition memory were investigated with Type-2 signal detection receiver operating characteristic (ROC) analysis, which provides a measure of metacognitive monitoring. Experiment 1 demonstrated a frequency-based mirror effect, with a higher hit rate and lower…

  19. The Flynn Effect in Sibships: Investigating the Role of Age Differences between Siblings

    ERIC Educational Resources Information Center

    Sundet, Jon Martin; Eriksen, Willy; Borren, Ingrid; Tambs, Kristian

    2010-01-01

    The aim of the study was to investigate the relationship between the Flynn effect and the effects of age differences between siblings on the intelligence difference between them. In Norway, the secular trends in intelligence-test score means vary both in magnitude and direction. We identified three periods: one period where the mean intelligence…

  20. Assessing the Effectiveness of Parent-Child Interaction Therapy with Language Delayed Children: A Clinical Investigation

    ERIC Educational Resources Information Center

    Falkus, Gila; Tilley, Ciara; Thomas, Catherine; Hockey, Hannah; Kennedy, Anna; Arnold, Tina; Thorburn, Blair; Jones, Katie; Patel, Bhavika; Pimenta, Claire; Shah, Rena; Tweedie, Fiona; O'Brien, Felicity; Leahy, Ruth; Pring, Tim

    2016-01-01

    Parent-child interaction therapy (PCIT) is widely used by speech and language therapists to improve the interactions between children with delayed language development and their parents/carers. Despite favourable reports of the therapy from clinicians, little evidence of its effectiveness is available. We investigated the effects of PCIT as…

  1. Group Investigation Effects on Achievement, Motivation, and Perceptions of Students in Singapore

    ERIC Educational Resources Information Center

    Tan, Ivy Geok Chin; Sharan, Shlomo; Lee, Christine Kim Eng

    2007-01-01

    In an experiment conducted in 7 eighth-grade (Ages 13-14) classes in Singapore, the authors evaluated the effects of the group investigation method of cooperative learning versus the effects of the traditional whole-class method of instruction on students' academic achievement and on their motivation to learn. The authors also investigated…

  2. The Effects of Teachers’ Motivational Strategies on Learners’ Motivation: A Controlled Investigation of Second Language Acquisition

    ERIC Educational Resources Information Center

    Moskovsky, Christo; Alrabai, Fakieh; Paolini, Stefania; Ratcheva, Silvia

    2013-01-01

    While consensus exists about the critical role of learners’ motivation in second language acquisition, controlled investigations of the effects of teachers’ motivational strategies are limited. The research reported here used a quasi-experimental design to assess the effects of motivational strategies used by Saudi English as a foreign language…

  3. QCD investigation of polarization effects in the inclusive photoproduction of SUSY particles

    SciTech Connect

    Sadykhov, F.S.; Akhmedov, A.I.

    1995-10-01

    Polarization effects in the inclusive photoproduction of SUSY particles is investigated in QCD. Two-spin asymmetries are studied as functions of the transverse momentum, the effective mass of scalar pairs, and the scattering angle. It is shown that information about the masses of scalar quarks can be deduced from the analysis of spin asymmetry. 4 refs., 4 figs.

  4. Investigation of the effects of initial fluid film profile on pumping ring operation

    NASA Technical Reports Server (NTRS)

    Smith, P. J.; Keith, T. G., Jr.

    1982-01-01

    The effect of the initial fluid film profile on the pumping capacity of a pumping ring shaft seal has been investigated numerically. Linear, concave, convex and compound film shapes were considered. It was found that initial film shape has a pronounced effect on both the amount of fluid pumped and on the character of the flow pattern and pressure distribution within the film.

  5. An Investigation of the Effectiveness of Concept Mapping on Turkish Students' Academic Success

    ERIC Educational Resources Information Center

    Erdogan, Yavuz

    2016-01-01

    This paper investigates the experimental studies which test the effectiveness of the concept mapping instructional strategy compared to the traditional teaching method. Meta-analysis was used to calculate the effect size of the concept mapping strategy on academic success. Therefore, the analysis includes experimental studies conducted in Turkey…

  6. An Investigation into the Life Experiences and Beliefs of Teachers Exhibiting Highly Effective Classroom Management Behaviors

    ERIC Educational Resources Information Center

    Holt, Chuck; Hargrove, Pauline; Harris, Sandra

    2011-01-01

    The purpose of this study was to investigate the life experiences and beliefs of highly effective teachers exhibiting effective classroom management. This study explores the beliefs, background, and experiences of exemplary teachers in the area of classroom management. The goal of this study was to develop a deeper understanding of how individuals…

  7. Can Schools Achieve Both Quality and Equity? Investigating the Two Dimensions of Educational Effectiveness

    ERIC Educational Resources Information Center

    Kyriakides, L.; Creemers, B. P. M.

    2011-01-01

    This article investigates the extent to which schools can achieve both equity and quality. Data emerged from two effectiveness studies in teaching mathematics and Greek language, which were conducted to test the validity of the dynamic model of educational effectiveness. Separate multilevel analyses for each subject were conducted and it was found…

  8. An Investigation into the Effects of Alcohol Use in Ontario Schools.

    ERIC Educational Resources Information Center

    White, James; And Others

    The purpose of this study was to determine the effects of alcohol use on student behaviors in Ontario schools. The study was designed to investigate the prevalence of alcohol use by students in grades 7-13 and the effects of drinking on classroom and school behaviors by interviewing both students and teachers. The teachers were surveyed to…

  9. Investigating Factors Related to the Effects of Time-Out on Stuttering in Adults

    ERIC Educational Resources Information Center

    Franklin, Diane E.; Taylor, Catherine L.; Hennessey, Neville W.; Beilby, Janet M.

    2008-01-01

    Background: Response-contingent time-out has been shown to be an effective technique for enhancing fluency in people who stutter. However, the factors that determine individual responsiveness to time-out are not well understood. Aims: The study investigated the effectiveness of using response-contingent time-out to reduce stuttering frequency in…

  10. Investigation of the influence of capillary effect on operation of the loop heat pipe

    NASA Astrophysics Data System (ADS)

    Mikielewicz, Dariusz; Błauciak, Krzysztof

    2014-09-01

    In the paper presented are studies on the investigation of the capillary forces effect induced in the porous structure of a loop heat pipe using water and ethanol ad test fluids. The potential application of such effect is for example in the evaporator of the domestic micro-CHP unit, where the reduction of pumping power could be obtained. Preliminary analysis of the results indicates water as having the best potential for developing the capillary effect.

  11. Moessbauer studies of Sr{sub 2}FeO{sub 4} to pressures of 20 GPa

    SciTech Connect

    Hearne, G.R. |; Pasternak, M.P.; Rozenberg, G.

    1995-09-01

    The transport and magnetic properties of the antiferromagnetic semiconductor Sr{sub 2}FeO{sub 4} (Fe{sup 4+}, d{sup 4}) were probed by resistance studies and {sup 57}Fe Moessbauer spectroscopy to 20 GPa using a diamond-anvil cell. The main conclusions of this work are that beyond the onset of the semiconductor-metal transition at {approx}17(1) GPa determined in the resistance studies: (1) the compound is still magnetic and, (2) there is no charge disproportionation of the form: 2Fe{sup 4+} {yields} Fe{sup 3+} + Fe{sup 5+}. The quadrupole splitting ({delta}E{sub Q}) at room temperature (RT) decreases from 0.42 mm/s at ambient pressure to a minimum of 2.2 mm/s at {approx}5.5 GPa. Beyond 5.5 GPa {delta}E{sub Q} at RT increases monotonically reaching 0.5 mm/s at 20 GPa. In the 0-10 GPa pressure range the Neel temperature T{sub N}, is pinned at 60-70 K reaching values of 135(5) K at 19 GPa where the compound is metallic. At 19 GPa and T {much_lt} T{sub N} a simplified magnetic spectrum having an internal magnetic field of {approx}25 T and a substantial quadrupole interaction is obtained.

  12. Mineralogical diversity (spectral reflectance and Moessbauer data) in compositionally similar impact melt rocks from Manicouagan Crater, Canada

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Bell, J. F., III; Golden, D. C.; Lauer, H. V., Jr.

    1993-01-01

    Meteoritic impacts under oxidizing surface conditions occur on both earth and Mars. Oxidative alteration of impact melt sheets is reported at several terrestrial impact structures including Manicouagan, West Clearwater Lake, and the Ries Basin. A number of studies have advocated that a significant fraction of Martian soil may consist of erosional products of oxidatively altered impact melt sheets. If so, the signature of the Fe-bearing mineralogies formed by the process may be present in visible and near infrared reflectivity data for the Martian surface. Of concern is what mineral assemblages form in impact melt sheets produced under oxidizing conditions and what their spectral signatures are. Spectral and Moessbauer data for 19 powder samples of impact melt rock from Manicouagan Crater are reported. Results show for naturally occurring materials that composite hematite-pyroxene bands have minima in the 910-nm region. Thus many of the anomalous Phobos-2 spectra, characterized by a shallow band minimum in the near-IR whose position varies between approximately 850 and 1000 nm, can be explained by assemblages whose endmembers (hematite and pyroxene) are accepted to be present on Mars. Furthermore, results show that a mineralogically diverse suite of rocks can be generated at essentially constant composition, which implies that variations in Martian surface mineralogy do not necessarily imply variations in chemical composition.

  13. Characterization of magnetite in silico-aluminous fly ash by SEM, TEM, XRD, magnetic susceptibility, and Moessbauer spectroscopy

    SciTech Connect

    Gomes, S.; Francois, M.; Abdelmoula, M.; Refait, P.; Pellissier, C.; Evrard, O.

    1999-11-01

    Spinel magnetite contained in a silico-aluminous fly ash (originating from la Maxe's power plant, near Metz in the east of France) issued from bituminous coal combustion has been studied by scanning and transmission electron microscopy linked with energy dispersive spectroscopy. X-ray diffraction, susceptibility measurements, and Moessbauer spectroscopy. The results show that in this magnetite Mg is strongly substituted for Fe and the chemical formula is closer to MgFe{sub 2}O{sub 4} than Fe{sub 3}O{sub 4}. Magnetite also contains Mn, Ca, and Si elements, but at a lower proportion. The results are compatible with the chemical formula Fe{sub 2.08}Mg{sub 0.75}Mn{sub 0.11}Ca{sub 0.04}Si{sub 0.02}O{sub 4} and crystallochemical formula [Fe{sup 2{minus}}{sub 0.92}Ca{sup 2+}{sub 0.06}Si{sup 4+}{sub 0.02}]{sup tetra}[Fe{sup 3+}Fe{sup 2+}{sub 0.16}Mg{sup 2+}{sub 0.73}Mn{sup 2+}{sub 0.11}]{sup octa}O{sub 4}, showing the cation distribution on octahedral and tetrahedral sites of the spinel structure. The reason Mg element is not incorporated in soluble surface salt and in glass composition of the silico-aluminous fly ashes is now understood.

  14. The Incredible Diversity of Fe-bearing Phases at Gusev Crater, Mars, According to the Mars Exploration Rover Moessbauer Spectrometer

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Klingelhoefer, G.; Schroeder, C.; Rodionov, D. S.; Ming, D. W.; Yen, A.

    2006-01-01

    The Mars Exploration Rover (MER) Spirit landed on the plains of Gusev Crater on 4 January 2004. One primary scientific objective for the mission is to characterize the mineralogical and elemental composition of surface materials, searching for evidence of water and clues for assessing past and current climates and their suitability for life [1]. The role of the Moessbauer (MB) spectrometer on Spirit is to provide quantitative information about the distribution of Fe among its oxidation and coordination states, identification of Fe-bearing phases, and relative distribution of Fe among those phases. The speciation and distribution of Fe in Martian rock and soil constrains the primary rock types, redox conditions under which primary minerals crystallized, the extent of alteration and weathering, the type of alteration and weathering products, and the processes and environmental conditions for alteration and weathering. In this abstract, we discuss the incredible diversity of Fe-bearing phases detected by Spirit s MB instrument during its first 540 sols of exploration at Gusev crater [2,3].

  15. Acidic properties of binary oxide catalysts. II. Moessbauer spectroscopy and pyridine adsorption for iron supported on magnesia, alumina, and titania

    SciTech Connect

    Connell, G.; Dumesic, J.A.

    1986-11-01

    The acidic properties of MgO, Al/sub 2/O/sub 3/, and TiO/sub 2/ were studied using pyridine adsorption. Infrared spectroscopy and gravimetric adsorption measurements indicate no acid sites on MgO, while Lewis acid sites were observed on the surfaces of Al/sub 2/O/sub 3/ and TiO/sub 2/. Doping Fe onto MgO and Al/sub 2/O/sub 3/ was shown by Moessbauer spectroscopy to produce only highly coordinated Fe (e.g., sixfold coordination). A small amount of low coordination iron (e.g., fourfold coordination) was observed on TiO/sub 2/. Pyridine adsorption measurements showed that addition of Fe on MgO did not generate acidity, whereas iron produced a small number of sites on Al/sub 2/O/sub 3/ and iron addition caused a selective poisoning and strengthening of the acid sites on TiO/sub 2/. All acids in this series of single component and binary component oxides were Lewis acids. A model of Lewis acidity is proposed in that the existence of coordinatively unsaturated cations responsible for the acidic properties can be predicted using Pauling's electrostatic bond strength rules. This model is also shown to be valid for iron cations deposited on SiO/sub 2/.

  16. Combined Backscatter Moessbauer Spectrometer and X Ray Fluorescence analyzer (BaMS/XRF) for planetary surface materials

    NASA Technical Reports Server (NTRS)

    Agresti, D. G.; Shelfer, T. D.; Pimperl, M. M.; Wills, E. L.; Morris, R. V.

    1991-01-01

    A backscatter Moessbauer spectrometer (BaMS) with included x ray fluorescence (XRF) capability for the Mars Environment Survey (MESUR) Mission, which has been proposed by NASA for 1998, is being developed. The instrument will also be suitable for other planetary missions such as those to the Moon, asteroids, and other solid solar-system objects. The BaMS would be unique for MESUR in providing information about iron mineralogy in rocks, clays, and other surface materials, including relative proportions of iron-bearing minerals. It requires no sample preparation and can identify all the normal oxidation states of iron (3+, 2+, 0). Thus, BaMS is diagnostic for weathering and other soil-forming processes. Backscatter design allows the addition of XRF elemental analysis with little or no modification. The BaMS/XRF instrument complements the thermal analyzer with evolved gas analyzer (TA-EGA) and the alpha-proton x-ray spectrometer (APXS) proposed (along with BaMS) for geochemical analysis on MESUR.

  17. Effects of heat treatment and magnetoannealing on nanocrystalline Co-ferrite powders

    SciTech Connect

    Wang, Y.C.; Ding, J.; Yin, J.H.; Liu, B.H.; Yi, J.B.; Yu, S.

    2005-12-15

    This work consists of three parts: the effects of heat treatment (slow cooling and quenching), magnetoannealing, and postannealing of samples with induced anisotropy. It has been found that noncomplete inverse spinel structure was the result after annealing at higher temperature and quenching. Our Moessbauer spectroscopy study confirmed noncomplete inverse structure after quenching, while inverse spinel structure was formed after slow cooling. The kinetics of the formation of induced anisotropy during magnetoannealing has been investigated in this study. Reduction of crystalline magnetic anisotropy was observed, as coercivity decreased after magnetoannealing. The change of remanence ratio and coercivity followed the expected equations for ion diffusion. A relative large anisotropy in magnetization was evident. A postannealing resulted in the conversion into the initial isotropic stage. The process could be well described using the equations of ion diffusion.

  18. Investigation of biological effects of some Mannich Bases containing Bis-1,2,4- Triazole.

    PubMed

    Parlak, A E; Celik, S; Karatepe, M; Turkoglu, S; Alayunt, N O; Dastan, S D; Ulas, M; Sandal, S; Tekin, S; Koparir, M

    2016-01-01

    In this study, the effects of Mannich bases containing bis-1,2,4-triazole on the levels of in vivo malondialdehyde (MDA) and antioxidant vitamins (A, E, C) were examined in serum, livers and kidneys of rats. DA and vitamin (A, E, C) levels were determined by high performance liquid chromatography (HPLC). Antioxidant effect was investigated by determining the MDA levels in Saccharomyces cerevisiae cells as in vitro. Furthermore, the antitumor effects of compounds were investigated against MCF-7 human breast cancer cells. Interrelations of results among control and compound groups were evaluated using SPSS statistical software package. As a result, some of the compounds showed effective biological activity when compared to control conditions. The test compounds used in this study may be effective for utilization in the selection and design of model compounds for further studies. PMID:27453272

  19. Comparative Investigation of Protective Effects of Metyrosine and Metoprolol Against Ketamine Cardiotoxicity in Rats.

    PubMed

    Ahiskalioglu, Ali; Ince, Ilker; Aksoy, Mehmet; Ahiskalioglu, Elif Oral; Comez, Mehmet; Dostbil, Aysenur; Celik, Mine; Alp, Hamit Hakan; Coskun, Resit; Taghizadehghalehjoughi, Ali; Suleyman, Bahadir

    2015-10-01

    This study investigated the effect of metyrosine against ketamine-induced cardiotoxicity in rats and compared the results with the effect of metoprolol. In this study, rats were divided into groups A, B and C. In group A, we investigated the effects of a single dose of metyrosine (150 mg/kg) and metoprolol (20 mg/kg) on single dose ketamine (60 mg/kg)-induced cardiotoxicity. In group B, we investigated the effect of metyrosine and metoprolol, which were given together with ketamine for 30 days. In group C, we investigated the effect of metyrosine and metoprolol given 15 days before ketamine and 30 days together with ketamine on ketamine cardiotoxicity. By the end of this process, we evaluated the effects of the levels of oxidant-antioxidant parameters such as MDA, MPO, 8-OHGua, tGSH, and SOD in addition to CK-MB and TP I on cardiotoxicity in rat heart tissue. The experimental results show that metyrosine prevented ketamine cardiotoxicity in groups A, B and C and metoprolol prevented it in only group C. PMID:25503950

  20. Resonance Counters as the Best Tool for the Investigations in Material Science

    SciTech Connect

    Belyaev, A. A.; Irkaev, S. M.; Panchuck, V. V.; Semenov, V. G.; Volodin, V. S.

    2008-10-28

    Sensitivity and resolution play a crucial role when Moessbauer spectroscopy is used in the materials science. Application of resonance counters in Moessbauer spectrometers allows us to increase the parameters mentioned above, and also signal-to-noise ratio considerably. The last one provides diminishing the time needed for obtaining given statistical accuracy. We carried out investigations of development of optimal counters for following isotopes: {sup 57}Fe, {sup 119}Sn, and {sup 151}Eu. Influence of different parameters of resonant radiation converters on experimental results was considered theoretically. Optimization of design has been performed using mathematical modeling based on Monte-Carlo method. Comparison of different types of counters used for resonant detecting was carried out. Results of experimental works on selection of efficient radiation converters are given. Comparison of scintillation and gas resonance counters was carried out. FeAl and FeGe{sub 2} alloys and K{sub 2}MgFe(CN){sub 6} have been used as converters for experiments with {sup 57}Fe-isotope, CaSnO{sub 3} has been used for {sup 119}Sn and Eu{sub 2}O{sub 3} and EuF{sub 3}--for {sup 151}Eu isotope. Gamma-optical scheme for versatile spectrometer, which expands the range of application of resonant detection for other Moessbauer isotopes, was suggested.

  1. The training effects of dance aerobics: A review with an emphasis on the perspectives of investigations.

    PubMed

    Zaletel, Petra; Gabrilo, Goran; Perić, Mia

    2013-05-01

    The training effects of contemporary aerobics programmes (hi lo, dance aerobics, step aerobics, aqua aerobics etc.) have been frequently investigated. However, we found no recent paper which reviewed aerobic programmes with regard to their training effectiveness, characteristics of the subjects involved, variables of interest and experimental design. In this paper we summarise the findings of more than 40 studies published in the 2000-2011 period that investigated the training effects of different forms of contemporary aerobics. In this review, the studies are grouped according to their characteristics (sample of subjects, variables of interest, study design, effects, etc.). Around 80% of the investigations dealt with females, with adults being most commonly observed. In the majority of investigations, the authors studied different variables at the same time (morphological anthropometric, motor, cardiovascular, biochemical indices, etc.). In recent studies a trend toward a psychological status examination is evident. In most instances positive training effects on motor-endurance and varsity of physiological variables are declared throughout a training period of 8 to 12 weeks. However, the positive changes in anaerobic endurance are not evidenced. Knowing the tendency of the overall increase of certain psychological disorders in population (including depression) there are indications that future, potentially highly interesting studies will deal with the psychological status of adults and older subjects. PMID:23914499

  2. Performance and Design Investigation of Heavy Lift Tiltrotor with Aerodynamic Interference Effects

    NASA Technical Reports Server (NTRS)

    Yeo, Yyeonsoo; Johnson, Wayne

    2007-01-01

    The aerodynamic interference effects on tiltrotor performance in cruise are investigated using comprehensive calculations, to better understand the physics and to quantify the effects on the aircraft design. Performance calculations were conducted for 146,600-lb conventional and quad tiltrotors, which are to cruise at 300 knots at 4000 ft/95 deg F condition. A parametric study was conducted to understand the effects of design parameters on the performance of the aircraft. Aerodynamic interference improves the aircraft lift-to-drag ratio of the baseline conventional tiltrotor. However, interference degrades the aircraft performance of the baseline quad tiltrotor, due mostly to the unfavorable effects from the front wing to the rear wing. A reduction of rotor tip speed increased the aircraft lift-to-drag ratio the most among the design parameters investigated.

  3. Frequency and fluid effects on elastic properties of basalt: Experimental investigations

    NASA Astrophysics Data System (ADS)

    Adelinet, M.; Fortin, J.; Guéguen, Y.; Schubnel, A.; Geoffroy, L.

    2010-01-01

    In order to investigate the effects of fluid and frequency on the elastic properties, we performed hydrostatic experiments on an Icelandic basalt specimen under both dry and saturated conditions. This basalt is characterized by a bimodal porosity, i.e., cracks and equant pores. The elastic properties -bulk moduli in our case- were investigated under high pressure through two experimental methods: (1) a classical one using ultrasonic P- and S-waves velocities (frequency 106 Hz), (2) and a new one, using oscillation tests (frequency 10-2 Hz). In dry condition, experimental data show no significant difference between high (HF) and low (LF) frequency bulk moduli. However, in saturated conditions, two effects are highlighted: a physico-chemical effect emphasized by a difference between drained and dry moduli, and a squirt-flow effect evidenced by a difference between HF and LF undrained moduli.

  4. Constraints on the oxidation state of the mantle: An electrochemical and sup 57 Fe Moessbauer study of mantle-derived ilmenites

    SciTech Connect

    Virgo, D.; Luth, R.W. ); Moats, M.A.; Ulmer, G.C. )

    1988-07-01

    Ilmenite samples from four kimberlite localities were studied using electrochemical, Moessbauer spectroscopic, and microprobe analytical techniques in order to infer the oxidation state of their source regions in the mantle. The values of Fe{sup 3+}/{Sigma}Fe calculated from analyses, using three different electron microanalytical instruments assuming ilmenite stoichiometry, are consistently higher than those derived from the Moessbauer data, by as much as 100%. Furthermore, the range in Fe{sup 3+}/{Sigma}Fe calculated using the analyses from different instruments and/or different correction schemes is nearly as large. Thus Fe{sup 3+}/{Sigma}Fe calculated from microprobe analyses should be taken with caution, even if the precision appears high. {sup 57}Fe Moessbauer spectroscopy on the electrochemical experiment run products demonstrates that Fe{sup 3+}/{Sigma}Fe is significantly lower than it is for the natural C-bearing ilmenites. In contrast, the ilmenite that lacked C did not change Fe{sup 3+}/{Sigma}Fe during the electrochemical experiment. Examination of the reduced samples with SEM established that the natural, single-phase ilmenites exsolved during the electrochemical experiment to form ilmenite{sub ss} + spinel{sub ss}. The initial, reduced trends in the electrochemical experiments for the C-bearing ilmenites are attributed to disequilibrium interactions between the decomposing sample and the evolved gas in the electrochemical cell and do not represent the quenched mantle memory nor the intrinsic f{sub O{sub 2}} of the sample prior to reduction. Furthermore, the oxidized f{sub O{sub 2}} trend is interpreted, for the carbon-bearing samples, are representing the f{sub O{sub 2}} of the ilmenite{sub ss} + spinel{sub ss} assemblage and not the intrinsic f{sub o{sub 2}} of the mantle-derived ilemnite{sub ss}.

  5. Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, {sup 57}Fe Moessbauer spectroscopy and thermal studies

    SciTech Connect

    Travnicek, Zdenek; Herchel, Radovan; Mikulik, Jiri; Zboril, Radek

    2010-05-15

    Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN){sub 5}NO].H{sub 2}O (1), where tet=N,N'-bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN){sub 5}NO].2H{sub 2}O (2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]octadecane and [Cu(nme){sub 2}Fe(CN){sub 5}NO].H{sub 2}O (3), where nme=N-methylethylenediamine, were synthesized and characterized by elemental analyses, {sup 57}Fe Moessbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, {sup 57}Fe Moessbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe{sub 2}O{sub 4} and CuO. - Three heterobimetallic cyano-bridged copper(II) nitroprusside-based complexes of the general compositions of [Cu(L)Fe(CN){sub 5}NO].xH{sub 2}O, where L=N,N'-bis(3-aminopropyl)ethylenediamine (complex 1), 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]-octadecane (complex 2) and N-methylethylenediamine (complex 3), were synthesized, and fully structurally and magnetically characterized. SEM, EDS, XRD and {sup 57}Fe Moessbauer experiments were used for characterization of thermal decomposition products of complexes 2 and 3.

  6. Investigating doping effects on high-κ metal gate stack for effective work function engineering

    NASA Astrophysics Data System (ADS)

    Leroux, C.; Baudot, S.; Charbonnier, M.; Van Der Geest, A.; Caubet, P.; Toffoli, A.; Blaise, Ph.; Ghibaudo, G.; Martin, F.; Reimbold, G.

    2013-10-01

    The impact of additives (La, Al and Mg) at the SiO2/high-κ interface has been investigated through ab initio simulations and electrical measurements. Various gate stacks with additive below or the above high-κ dielectric are compared. Combination of capacitance versus gate bias measurement and internal photon emission is performed to demonstrate that the threshold voltage shift is related to a dipole formation at the SiO2/high-κ interface. The respective roles of aluminum and lanthanum are clearly identified as well as their sensitivity to roll-off. Impact of additive on metal gate function is studied. Finally, ab initio enables an analysis of the dipole formation with additive at the SiO2/HfO2 interface.

  7. Experimental investigation of the effects of naturalistic dieting on bulimic symptoms: moderating effects of depressive symptoms.

    PubMed

    Presnell, Katherine; Stice, Eric; Tristan, Jennifer

    2008-01-01

    Prospective studies suggest that dieting increases risk for bulimic symptoms, but experimental trials indicate dieting reduces bulimic symptoms. However, these experiments may be unrepresentative of real-world weight loss dieting. In addition, the fact that most dieters do not develop eating disorders suggests moderating factors may be important. Accordingly, we randomly assigned 157 female intermittent dieters to either diet as they usually do for weight loss or eat as they normally do when not dieting for 4 weeks. Naturalistic dieting halted the weight gain shown by controls, but did not result in significant weight loss. Although there was no main effect of the dieting manipulation on bulimic symptoms, moderation analyses indicated that naturalistic dieting decreased bulimic symptoms among participants with initially low depressive symptoms. Results suggest that self-initiated weight loss dieting is not particularly effective, which appears to explain several discrepancies in the literature. Additionally, depressive symptoms may be an important determinant of bulimic symptoms that eclipses the effects of naturalistic dieting on this outcome. PMID:17662503

  8. Moessbauer spectroscopy and magnetic characteristics of Zn{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0-1) nanoparticles

    SciTech Connect

    Ghasemi, Ali; Sepelak, Vladimir; Shirsath, Sagar E.; Liu Xiaoxi; Morisako, Akimitsu

    2011-04-01

    Zn{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0-1 in a step of 0.2) nanoparticles with different range of particle size including 5-10 nm and 200-250 nm have been prepared by sol-gel process. Moessbauer spectra at room temperature indicated that, with increasing cobalt content, there is a transition from paramagnetic to magnetically ordered-ferrimagnetic state. Magnetic properties were measured at 300 and 10 K using a Quantum Design MPMS-5S SQUID magnetometer. It was found that with an increase in cobalt content the saturation magnetization and coercivity increase.

  9. Effectiveness of PowerPoint-Based Lectures across Different Business Disciplines: An Investigation and Implications

    ERIC Educational Resources Information Center

    Burke, Lisa A.; James, Karen; Ahmadi, Mohammad

    2009-01-01

    The authors investigated business faculty members' degree of Power-Point (PPT) use across different functional areas in a business program and their use of specific PPT features. The authors also examined students' perceptions of PPT's effectiveness across different business courses (e.g., accounting, economics, management, business law,…

  10. Context Effects in Processing of Chinese Academic Words: An Eye-Tracking Investigation

    ERIC Educational Resources Information Center

    Jian, Yu-Cin; Chen, Ming-Lei; Ko, Hwa-wei

    2013-01-01

    This study investigated context effects of online processing of Chinese academic words during text reading. Undergraduate participants were asked to read Chinese texts that were familiar or unfamiliar (containing physics terminology) to them. Physics texts were selected first, and then we replaced the physics terminology with familiar words; other…

  11. Preliminary investigation of the effects of dye concentration on the output of a multiwavelength dye laser

    NASA Technical Reports Server (NTRS)

    Clark, I. O.; Burney, L. G.

    1974-01-01

    The effects of dye concentration on the output wavelength and energy of a multiwavelength dye laser were investigated. The dyes tested were Coumarin 2 in methyl alcohol and Rhodomine 6G, Acridine Red, and 7-diethylamino-4-methyl Coumarin (7DA 4MC) in ethyl alcohol.

  12. Meta-Analysis of Studies Investigating the Effects of Father Absence on Children's Cognitive Performance.

    ERIC Educational Resources Information Center

    Salzman, Stephanie A.

    A meta-analysis was conducted of 137 studies investigating the effects of father absence due to employment, military service, death, divorce, separation, or desertion on children's cognitive performance as assessed by scores on standardized intelligence, scholastic aptitude, and academic achievement tests and school grades. Aggregation of the…

  13. A Qualitative Investigation into the Characteristics and Effects of Music Accompanying Exercise

    ERIC Educational Resources Information Center

    Priest, David-Lee; Karageorghis, Costas I.

    2008-01-01

    The purpose of the present study was to identify the characteristics of music used to accompany physical exercise and investigate the effects of such music using a qualitative approach. This work underpins the further development of a theoretical structure that is still relatively new. Semi-structured interviews were conducted with a sample of…

  14. A Vodcasted, Cross-Disciplinary, Behavioral Neuroscience Laboratory Exercise Investigating the Effects of Methamphetamine on Aggression

    ERIC Educational Resources Information Center

    Shanks, Ryan A.; Southard, E. Megan; Tarnowski, Laura; Bruster, Matthew; Wingate, Stacia W.; Dalman, Nancy; Lloyd, Steven A.

    2011-01-01

    This article describes a laboratory experience utilizing videos to engage students in hypothesis-driven experimentation in behavioral neuroscience. It provides students with an opportunity to investigate the effects of chronic methamphetamine exposure on aggression in adult mice using a resident-intruder paradigm. Instructors and students only…

  15. Pilot Investigation of the Effectiveness of Respite Care for Carers of an Adult with Mental Illness

    ERIC Educational Resources Information Center

    Jardim, Claudia; Pakenham, Kenneth I.

    2009-01-01

    Informal carers of an adult with mental illness have asked that respite care be an integral component of mental health service provision. The present study involved a pilot investigation of the effectiveness of accessing respite care for carers of individuals with a mental illness. It was hypothesised that compared to carers who have not accessed…

  16. Investigating the Effectiveness of Individualized Feedback to Rating Behavior--A Longitudinal Study

    ERIC Educational Resources Information Center

    Knoch, Ute

    2011-01-01

    The effectiveness of individualized feedback on rater behavior has been investigated in several previous studies (e.g. Elder, Knoch, Barkhuizen, & von Randow, 2005; Lunt, Morton, & Wigglesworth, 1994; O'Sullivan & Rignall, 2007; Wigglesworth, 1993). The findings of these studies are somewhat inconclusive. However, all of these studies investigated…

  17. Investigating the Effect of Argument-Driven Inquiry in Laboratory Instruction

    ERIC Educational Resources Information Center

    Demircioglu, Tuba; Ucar, Sedat

    2015-01-01

    The aim of this study is to investigate the effect of argument-driven inquiry (ADI) based laboratory instruction on the academic achievement, argumentativeness, science process skills, and argumentation levels of pre-service science teachers in the General Physics Laboratory III class. The study was conducted with 79 pre-service science teachers.…

  18. Exploring Resiliency within Schools: An Investigation of the Effects of Protective Factors

    ERIC Educational Resources Information Center

    Phillips, Matthew D.; Turner, Michael G.; Holt, Thomas J.

    2014-01-01

    Although research has explored the effects of protective factors on fostering resiliency within "individuals," the same level of inquiry has not emerged investigating the causes of why high-risk "organizations" are resilient to serious violent delinquency. One type of organization that seems particularly appropriate for…

  19. The Effect of Sublexical and Lexical Frequency on Speech Production: An fMRI Investigation

    ERIC Educational Resources Information Center

    Shuster, Linda I.

    2009-01-01

    There is no consensus regarding the fundamental phonetic units that underlie speech production. There is, however, general agreement that the frequency of occurrence of these units is a significant factor. Investigators often use the effects of manipulating frequency to support the importance of particular units. Studies of pseudoword production…

  20. Two Phonetic-Training Procedures for Young Learners: Investigating Instructional Effects on Perceptual Awareness

    ERIC Educational Resources Information Center

    Lacabex, Esther Gómez; Gallardo del Puerto, Francisco

    2014-01-01

    This study investigated the effect of two distinct computer-based phonetic training procedures administered in an English-as-a-foreign-language (EFL) classroom with young learners. Students' perceptual awareness of the occurrence of an English schwa in an unstressed position in content words was tested in two experimental groups, which…

  1. An Investigation of Teachers' Perceptions of the Effects of Class Size on Teaching

    ERIC Educational Resources Information Center

    Almulla, Mohammed Abdullatif

    2015-01-01

    This study investigates the perceptions of Saudi Arabian primary school teachers in Years 4, 5 and 6 and discusses the effects of class size on teaching. The data comes from 30 teachers who teach small classes in two private schools, and 37 who teach large classes in two state schools in Alhafouf, Saudi Arabia. The study discusses whether…

  2. An Investigation of Transformational Leadership and Organizational Effectiveness in Small College Settings.

    ERIC Educational Resources Information Center

    Murray, Frances; Feitler, Fred C.

    The ways in which current theories of leadership relate to perceptions of organizational effectiveness are examined in a study looking at these interactions and relevant demographic factors in 11 small, private, midwestern colleges. A model of transactional and transformational leadership proposed by Bass (1985) is investigated along with an…

  3. An experimental investigation of the effect of upper surface blowing on dynamic stall

    NASA Technical Reports Server (NTRS)

    Tso, Jin

    1993-01-01

    An experimental investigation of the effect of upper surface blowing on dynamic stall was conducted. Progress made during the period from Jun. to Dec. 1993 is summarized. Topics covered include VR-7 wing model, pulse valve, and wing/load cell junction.

  4. Investigations of the inhibitory effects of tocopherol (vitamin E) on free radical deterioration of cellular membranes

    NASA Technical Reports Server (NTRS)

    Richardson, D.

    1975-01-01

    The inhibitory effects are investigated of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate on the free radical deterioration of cellular membranes. The level of toxicity of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate in mice is determined.

  5. Investigating the Effects of Prompts on Argumentation Style, Consensus and Perceived Efficacy in Collaborative Learning

    ERIC Educational Resources Information Center

    Harney, Owen M.; Hogan, Michael J.; Broome, Benjamin; Hall, Tony; Ryan, Cormac

    2015-01-01

    This paper investigates the effects of task-level versus process-level prompts on levels of perceived and objective consensus, perceived efficacy, and argumentation style in the context of a computer-supported collaborative learning session using Interactive Management (IM), a computer facilitated thought and action mapping methodology. Four…

  6. An Investigation of the Effectiveness of Vocabulary Learning Strategies on Iranian EFL Learners' Vocabulary Test Score

    ERIC Educational Resources Information Center

    Rahimy, Ramin; Shams, Kiana

    2012-01-01

    This study aims to investigate the effectiveness of vocabulary learning strategies on Iranian EFL learners' vocabulary test score. To achieve this aim, fifty Intermediate level students from Kish English Institute were randomly selected from among fifteen classes after administering the Oxford Placement Test (OPT). Then, an intermediate level…

  7. Investigation of Microopto-eletromechanical Angular Velocity and Acceleration Transducers based on Optical Tunneling Effect

    NASA Astrophysics Data System (ADS)

    Busurin, V. I.; Lwin, Naing Htoo; Tuan, Pham Anh

    In this paper the possibility of microopto-electromechanical (MOEM) angular velocity and acceleration transducers based on optical tunneling effect (OTE) is considered. The generalized model of MOEM transducers with various types of sensing elements (SE) is developed, transfer functions are investigated, and the errors with various design parameters of transducers are estimated.

  8. Institutional Pedagogy and Semiosis: Investigating the Missing Link between Peirce's Semiotics and Effective Semiotics

    ERIC Educational Resources Information Center

    Pesce, Sebastien

    2011-01-01

    My aim in this paper is to show the relevance of an "effective semiotics"; that is, a field study based upon Peirce's semiotics. The general context of this investigation is educational semiotics rather than semiotics of teaching: I am concerned with a general approach of educational processes, not with skills and curricula. My paper is grounded…

  9. An Empirical Investigation of the Multiple Constituencies Model of Organizational Effectiveness.

    ERIC Educational Resources Information Center

    Cameron, Kim S.

    The multiple constituencies model of organizational effectiveness was investigated in 1980-1981 with 29 four-year colleges and universities in the Northeast United States. A performance profile for individual organizations and a preference profile for different constituencies of the organizations were obtained, using the same dimensions of…

  10. An Investigation of the Partial-Assignment Completion Effect on Students' Assignment Choice Behavior

    ERIC Educational Resources Information Center

    Hawthorn-Embree, Meredith L.; Skinner, Christopher H.; Parkhurst, John; Conley, Elisha

    2011-01-01

    This study was designed to investigate the partial assignment completion effect. Seventh-grade students were given a math assignment. After working for 5 min, they were interrupted and their partially completed assignments were collected. About 20 min later, students were given their partially completed assignment and a new, control assignment…

  11. Gateway Health Behaviors in College Students: Investigating Transfer and Compensation Effects

    ERIC Educational Resources Information Center

    Nigg, Claudio Renato; Lee, Hye-ryeon; Hubbard, Amy E.; Min-Sun, Kim

    2009-01-01

    Objective: There is a dearth of studies on the mechanisms of multiple risk behaviors, even though these behaviors are significant public health issues. The authors investigated whether health behavior interventions have transfer or compensatory effects on other health behaviors. Participants and Methods: The authors looked at transfer and…

  12. Investigating the Modality and Redundancy Effects for Learners with Persistent Pain

    ERIC Educational Resources Information Center

    Smith, Alexander; Ayres, Paul

    2016-01-01

    Two experiments were conducted to investigate how individuals with persistent pain would respond to instructional materials designed to promote the modality and redundancy effects. It was predicted that persistent pain would reduce the positive impact of narrated text due to reduced working memory capacity. One hundred thirty-seven full-time…

  13. Investigating the Effectiveness of an Educational Card Game for Learning How Human Immunology Is Regulated

    ERIC Educational Resources Information Center

    Su, TzuFen; Cheng, Meng-Tzu; Lin, Shu-Hua

    2014-01-01

    This study was conducted in an attempt to investigate the effectiveness of an educational card game we developed for learning human immunology. Two semesters of evaluation were included to examine the impact of the game on students' understanding and perceptions of the game-based instruction. Ninety-nine senior high school students (11th…

  14. Investigation of the effects of short chain processing additives on polymers

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Stclair, T. L.; Pratt, J. R.

    1986-01-01

    The effects of low level concentrations of several short chain processing additives on the properties of the 4,4'-bis(3,4-dicarboxyphenoxy) diphenylsulfide dianhydride (BDSDA)/4,4'-diaminodiphenyl ether (ODA)/1,3'-diaminobenzene (m-phenylene diamine) (MPA) (422) copolyimide were investigated. It was noted that 5 percent MPD/phthalic anhydride (PA) is more effective than 5 percent ODA/PA and BDSDA/aniline (AN) in strengthening the host material. However, the introduction of 10 percent BDSDA/AN produces disproportionately high effects on free volume and free electron density in the host copolyimide.

  15. Experimental investigation of heat transfer and effectiveness in corrugated plate heat exchangers having different chevron angles

    NASA Astrophysics Data System (ADS)

    Kılıç, Bayram; İpek, Osman

    2016-06-01

    In this study, heat transfer rate and effectiveness of corrugated plate heat exchangers having different chevron angles were investigated experimentally. Chevron angles of plate heat exchangers are β = 30° and β = 60°. For this purpose, experimentally heating system used plate heat exchanger was designed and constructed. Thermodynamic analysis of corrugated plate heat exchangers having different chevron angles were carried out. The heat transfer rate and effectiveness values are calculated. The experimental results are shown that heat transfer rate and effectiveness values for β = 60° is higher than that of the other. Obtained experimental results were graphically presented.

  16. Investigation of difficult component effects on FEM vibration prediction for the AH-1G helicopter

    NASA Technical Reports Server (NTRS)

    Dompka, Robert V.

    1988-01-01

    Under the NASA-sponsored Design Analysis Methods for Vibrations program, a series of ground vibration tests and NASTRAN finite element model correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Secondary structure and damping were found to have significant effects on the frequency response of the airframe above 15 Hz. The nonlinear effects of thrust stiffening and elastomeric mounts on the low-frequency pylon modes below the main rotor were also significant.

  17. Investigation of 360-degree instrumentation effects: application of the Rasch rating scale model.

    PubMed

    Kulas, John T; Hannum, Kelly M

    2007-01-01

    Performance appraisals have been frequently investigated for inaccuracies attributable to raters. In addition to rater contributions, problems in measurement can arise from properties of instrumentation. If administered items do not parallel the full range of employee performance, a restriction of range can occur. Here employees are rated similarly (no distinction made) not because of rater error, but because of an instrument floor or ceiling effect. A RASCH measurement procedure was applied to a 360-degree dataset in order to uncover potential instrumentation effects. A similar magnitude ceiling effect was found across rater categories. It is recommended that performance appraisal practitioners consider including items of greater difficulty in their criterion measures. PMID:18250526

  18. An investigation into field effects of consciousness from the perspectives of Maharishi's Vedic Science and physics

    NASA Astrophysics Data System (ADS)

    Kleinschnitz, Kurt Warren

    1997-05-01

    A long-range field effect of consciousness has been reported repeatedly in the scientific literature over the past twenty years. This phenomenon is called the Maharishi Effect, after Maharishi Mahesh Yogi, the first to predict it. The Maharishi Effect is the phenomenon of improved societal trends resulting from the practice of the Transcendental Meditationoler program or group practice of the TM-Sidhioler program by a small fraction of a population. The Maharishi Effect is fundamentally a phenomenon of radiation of evolutionary influence arising from the enlivenment of pure consciousness, the unified field of natural law, in the perspective of Maharishi's Vedic Science. This perspective is corroborated by forty-three published or presented papers reporting on results of Maharishi Effect interventions world-wide at city, national, international, and global scales. Present day standard- model physics and physiology do not account for the outcomes of the research on the Maharishi Effect. Because the observed societal impact of the Maharishi Effect influence must be based in an impact on the individual, and investigators report detection of the effect in individual physiological measurements, a simple robust indicator for the effect might aid physiologists and physicists in the effort to extend their sciences to include such field effects of consciousness. Thus, this dissertation reports on two experiments investigating simple, robust, objective indicators for the effect. The dissertation concludes on a practical note with a description of the promise, available through concerted utilization of the knowledge and technologies of consciousness in Maharishi's Vedic Science, for enhanced national and global security in the face of unprecedented nuclear, biological, and genetic threats for which the modern sciences offer few sensible solutions. ftnolerTranscendental Meditation and TM-Sidhi are service marks registered in the United States Patent and Trademark Office

  19. Investigation on the structural effect of lignin during the hydrogenolysis process.

    PubMed

    Shu, Riyang; Long, Jinxing; Xu, Ying; Ma, Longlong; Zhang, Qi; Wang, Tiejun; Wang, Chenguang; Yuan, Zhengqiu; Wu, Qingyun

    2016-01-01

    Structure has a significant effect on the lignin degradation, so the investigation of structural effect on the lignin depolymerization is important and imperative. In this study, hydrogenolysis of three typical lignins with different structures, dealkaline lignin, sodium lignosulfonate and organosolv lignin, was intensively compared over the synergistic catalyst of CrCl3 and Pd/C. The effects of reaction temperature, time, hydrogen pressure and catalyst dosage on the catalytic performance of lignin species were investigated. The structure evolution of lignins during the hydrogenolysis process was also compared. The results showed that organosolv lignin was more sensitive for hydrogenolysis than others due to its high unsaturation degree and low molecular weight. Further analysis indicated that the hydrogenolysis, hydrodeoxygenation and repolymerization reactions took place and competed intensely. Wherein, the depolymerization products with unsaturated carbonyl groups were prone to repolymerize. And the methylation was helpful to stabilize the depolymerization products and suppress the further repolymerization. PMID:26476159

  20. Visual Investigation of Heating Effect in Liver and Lung Induced by a HIFU Transducer

    NASA Astrophysics Data System (ADS)

    Karaböce, B.; Durmuş, H. O.

    The heating effect produced by a focused ultrasound transducer has been investigated by using visual techniques with a positioning system. Ultrasound power, distance, frequency and harmonics of heating effect was investigated. Three experiments were performed on TMM (Tissue Mimicking Material), sheep liver and sheep lung. HIFU (High Intensity Focused Ultrasound) transducer with a resonance frequency of 1.1 MHz and 3.3 MHz was used as source. Effect of ultrasound in liver and lung's pieces were displayed and dimension of cauterization has been measured. Previous temperature measurement results for TMM were compared with liver and lung measurement results so that it is possible to transfer the laboratory measurements to the clinical studies. All measurements were carried out in the system at TÜBİTAK UME (The Scientific and Technological Research Council of Turkey, the National Metrology Institute) Ultrasound laboratory.

  1. Experimental Investigation of Effectiveness of Magnetic Field on Food Freezing Process

    NASA Astrophysics Data System (ADS)

    Suzuki, Toru; Takeuchi, Yuri; Masuda, Kazunori; Watanabe, Manabu; Shirakashi, Ryo; Fukuda, Yutaka; Tsuruta, Takaharu; Yamamoto, Kazutaka; Koga, Nobumitsu; Hiruma, Naoya; Ichioka, Jun; Takai, Kiyoshi

    Recently, several food refrigeration equipments that utilize magnetic field have attracted much attention from food production companies, consumers and mass media. However, the effectiveness of the freezers is not scientifically examined. Therefore, the effectiveness should be clarified by experiments or theoretical considerations. In this study, the effect of weak magnetic field (about 0.0005 T) on freezing process of several kinds of foods was investigated by using a specially designed freezer facilitated with magnetic field generator. The investigation included the comparison of freezing curves, drip amount, physicochemical evaluations on color and texture, observation of microstructure, and sensory evaluation. From the results of the control experiments, it can be concluded that weak magnetic field around 0.0005 T provided no significant difference on temperature history during freezing and on the qualities of frozen foods, within our experimental conditions.

  2. A numerical investigation of the cooling effect of compressed natural gas throttling on engine delivery ratio

    SciTech Connect

    Yacoub, Y.; Marbun, L.; Bata, R.

    1999-01-01

    A theoretical study was conducted to investigate the cooling effect of throttling compressed natural gas during the pressure regulation process. The concept of using this effect in cooling down the induction air was investigated. A thermodynamic model was developed for a typical fuel delivery system used on a vehicle fueled with compressed natural gas. The model was based on a set of integral conservation laws applied to each component of the fueling system. Several heat exchanging arrangements between the throttled gas and the inlet air were examined. The effect of the added heat exchanger on engine delivery ratio was examined for different engine sizes as well as for different operating conditions. An increase of 1 to 2.5% in engine delivery ratio was predicted due to the added heat exchanger.

  3. Investigations on the heating effect of PE-LD induced by high-intensity focused ultrasound.

    PubMed

    Oehm, Lukas; Bach, Sascha; Majschak, Jens-Peter

    2016-08-01

    High-intensity focused ultrasound is widely applied in tissue treatment as well as for heating of solid polymer materials. Previous studies investigating the heating effect in polymer materials utilized sound transmission through water or other fluids at low HIFU power. In this study, the ultrasonic transducer possesses a solid sound conductor made of aluminum and a high HIFU power of above 100W was applied to heat solid PE-LD samples. Temperature measurements were performed by calibrated non-invasive infrared thermal imaging. A strong heating effect with heating above melting temperature and evaporation temperature within less than 1s of irradiation was observed. Furthermore, the acoustic coupling defined by the force applied by the ultrasonic applicator to the polymer material was found to be fundamental to induce the heating effect. This investigation reveals HIFU for new applications in the field of polymer processing. PMID:27208613

  4. Investigating size effects of complex nanostructures through Young-Laplace equation and finite element analysis

    SciTech Connect

    Lu, Dingjie; Xie, Yi Min; Huang, Xiaodong; Zhou, Shiwei; Li, Qing

    2015-11-28

    Analytical studies on the size effects of a simply-shaped beam fixed at both ends have successfully explained the sudden changes of effective Young's modulus as its diameter decreases below 100 nm. Yet they are invalid for complex nanostructures ubiquitously existing in nature. In accordance with a generalized Young-Laplace equation, one of the representative size effects is transferred to non-uniformly distributed pressure against an external surface due to the imbalance of inward and outward loads. Because the magnitude of pressure depends on the principal curvatures, iterative steps have to be adopted to gradually stabilize the structure in finite element analysis. Computational results are in good agreement with both experiment data and theoretical prediction. Furthermore, the investigation on strengthened and softened Young's modulus for two complex nanostructures demonstrates that the proposed computational method provides a general and effective approach to analyze the size effects for nanostructures in arbitrary shape.

  5. Investigation of Sterilization Effect by various Gas Plasmas and Electron Microscopic Observation of Bacteria

    NASA Astrophysics Data System (ADS)

    Sasaki, Yota; Takamatsu, Toshihiro; Uehara, Kodai; Oshita, Takaya; Miyahara, Hidekazu; Okino, Akitoshi; Ikeda, Keiko; Matsumura, Yuriko; Iwasawa, Atsuo; Kohno, Masahiro

    2014-10-01

    Atmospheric non-thermal plasmas have attracted attention as a new sterilization method. It is considered that factor of plasma sterilization are mainly reactive oxygen species (ROS). However, the sterilization mechanism hasn't been investigated in detail because conventional plasma sources have a limitation in usable gas species and lack variety of ROS. So we developed multi-gas plasma jet which can generate various gas plasmas. In this study, investigation of sterilization effect by various gas plasmas and electron microscopic observation of bacteria were performed. Oxygen, nitrogen, carbon dioxide, argon and air were used as plasma gas. To investigate gas-species dependence of sterilization effect, S.aureus was treated. As a result, nitrogen plasma and carbon dioxide plasma were effective for sterilization. To investigate sterilization mechanism, the surface of S.aureus was observed by scanning electron microscope. As a result, dimples were observed on the surface after irradiation of nitrogen plasma, but no change observed in the case of carbon dioxide plasma. These results suggest that bactericidal mechanism of nitrogen and carbon dioxide plasma should be different. In the presentation, Measurement result of ROS will be reported.

  6. Effects of Bending Radii on the Characteristics of Flexible Organic Solar Cells Investigated by Impedance Analysis.

    PubMed

    Kim, Hoonbae; Ye, Donghyun; Won, Beomhee; Yu, SeGi; Jung, Donggeun

    2016-05-01

    Flexible organic solar cells (OSCs) were fabricated on an indium-tin-oxide (ITO)/poly(ethylene terephthalate) (PET) substrate and were subjected to bending tests with various bending radii. We observed that the photovoltaic properties of the OSCs precipitously deteriorated at a bending radius ≤ 0.75 cm. In order to investigate the effects of the bending test, the changes in the surface morphology and the sheet resistance of the ITO-coated PET samples were investigated, and the photovoltaic properties of bent and unbent OSCs were evaluated. Thereafter, equivalent circuits for the OSCs were assumed and the change in their parameters, such as resistance and capacitance, was observed. PMID:27483935

  7. [Comparative investigation of locust's phototactic visual spectrum effect and phototactic response to spectral illumination].

    PubMed

    Liu, Qi-Hang; Zhou, Qiang

    2014-07-01

    To provide theoretical support for determining locust's phototactic spectrum, and explore locust's phototactic mechanism stimulated by light, utilizing AvaSpec fiber-optic spectrometer system and AvaLight-DHS, the investigation of locust's phototactic visual spectrum effect after light energy stimulated locust's vision system was carried out and on this basis, utilizing the investigated device of locust's phototactic response to spectral illumination, the discrepancy of locust's phototactic response to spectral illumination was certificated comparatively. The results show that the degree of locust's vision system absorbing the single spectrum photon of 430, 545 and 610 nm is significant and there exists difference, and the behavioral response to orange, violet, green, and blue spectral light has the difference in selective sensitivity, with the intensity of response to violet light being the strongest. The degree of response to orange light is the maximum, simultaneously, locust's vision system absorbing spectral photon energy has selective difference and requirement of illumination time, moreover, the sensitive degree of locust's visual system to spectrum and the strength of the lighting energy, influencing locust's phototactic response degree, and the micro-response of locust's phototactic vision physiology, led by the photoelectric effect of locust absorbing sensitive photon and converting photon energy, is the reason for locust's phototactic orientation response. In addition, locust's phototactic visual spectrum effect, only when the biological photoelectric effect of locust's visual system is stimulated by spectral illumination, can present the sensitivity of the spectral absorption effect, so, using the stronger ultraviolet stimulation characteristic of violet light, the different sensitive stimulation of orange, green, blue spectral light on locust's phototactic vision, and combining orange, violet, green, blue spectral light field mechanism reasonably, can

  8. Radiation and temperature effects on electronic components investigated under the CSTI high capacity power project

    NASA Technical Reports Server (NTRS)

    Schwarze, Gene E.; Niedra, Janis M.; Frasca, Albert J.; Wieserman, William R.

    1993-01-01

    The effects of nuclear radiation and high temperature environments must be fully known and understood for the electronic components and materials used in both the Power Conditioning and Control subsystem and the reactor Instrumentation and Control subsystem of future high capacity nuclear space power systems. This knowledge is required by the designer of these subsystems in order to develop highly reliable, long-life power systems for future NASA missions. A review and summary of the experimental results obtained for the electronic components and materials investigated under the power management element of the Civilian Space Technology Initiative (CSTI) high capacity power project are presented: (1) neutron, gamma ray, and temperature effects on power semiconductor switches, (2) temperature and frequency effects on soft magnetic materials; and (3) temperature effects on rare earth permanent magnets.

  9. A second international co-operative investigation into thioacetazone side-effects*

    PubMed Central

    Miller, A. B.; Nunn, A. J.; Robinson, D. K.; Ferguson, G. C.; Fox, Wallace; Tall, Ruth

    1970-01-01

    As part of a large-scale international, co-operative investigation into the side-effects produced by thioacetazone employed in the treatment of tuberculosis, an evaluation has been made of a supplement incorporating vitamins and an antihistamine as a prophylactic. Over a 12-week period of treatment, the additive supplement failed to reduce the over-all frequency of side-effects or the frequency of side-effects leading to a major departure from prescribed treatment. There was also no evidence that the more serious side-effects, particularly rashes, jaundice and agranulocytosis, were reduced by the additives, although the occurrence of vomiting, which was however infrequent, was reduced. In view of this lack of appreciable benefit, as well as the higher cost and impaired keeping properties of tablets containing thioacetazone plus isoniazid when the supplement is added, the use of the supplement as a prophylactic cannot be recommended. PMID:4098113

  10. Theoretical investigation of polarization effects in solution: Importance of solvent collective motions

    SciTech Connect

    Ishida, Tateki

    2015-01-22

    Recent theoretical studies on interesting topics related to polarization effects in solutions are presented. As one of interesting topics, ionic liquids (ILs) solvents are focused on. The collective dynamics of electronic polarizability through interionic dynamics and the effect of polarization in ILs, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF{sub 6}]), are studied with molecular dynamics simulation. Also, the time-dependent polarization effect on the probe betaine dye molecule, pyridinium N-phenoxide, in water is investigated by a time-dependent reference interaction site model self-consistent field (time-dependent RISM-SCF) approach. The importance of considering polarization effects on solution systems related to solvent collective motions is shown.

  11. Radiation and temperature effects on electronic components investigated under the CSTI high capacity power project

    SciTech Connect

    Schwarze, G.E. ); Niedra, J.M. ); Frasca, A.J. ); Wieserman, W.R. )

    1993-01-15

    The effects of nuclear radiation and high temperature environments must be fully known and understood for the electronic components and materials used in both the Power Conditioning and Control subsystem and the reactor Instrumentation and Control subsystem of future high capacity nuclear space power systems. This knowledge is required by the designer of these subsystems in order to develop highly reliable, long-life power systems for future NASA missions. A review and summary of the experimental results obtained for the electronic components and materials investigated under the power management element of the CSTI high capacity power project will be presented in this paper: (1) Neutron, gamma ray, and temperature effects on power semiconductor switches, (2) Temperature and frequency effects on soft magnetic materials; and (3) Temperature effects on rare-earth permanent magnets.

  12. Radiation and temperature effects on electronic components investigated under the CSTI High Capacity Power Project

    SciTech Connect

    Shwarze, G.E.; Niedra, J.M.; Frasca, A.J.; Wieserman, W.R.

    1994-09-01

    The effects of nuclear radiation and high temperature environments must be fully known and understood for the electronic components and materials used in both the Power Conditioning and Control subsystem and the reactor Instrumentation and Control subsystem of future high capacity nuclear space power systems. This knowledge is required by the designer of these subsystems in order to develop highly reliable, long-life power systems for future NASA missions. A review and summary of the experimental results obtained for the electronic components and materials investigated under the power management element of the CSTI high capacity power project will be presented in this paper: (1) Neutron, gamma ray, and temperature effects on power semiconductor switches, (2) Temperature and frequency effects on soft magnetic materials; and (3) Temperature effects on rare earth permanent magnets.

  13. Mesons in (2+1)-dimensional light front QCD: Investigation of a Bloch effective Hamiltonian

    NASA Astrophysics Data System (ADS)

    Chakrabarti, Dipankar; Harindranath, A.

    2001-11-01

    We study the meson sector of (2+1)-dimensional light front QCD using a Bloch effective Hamiltonian in the first nontrivial order. The resulting two-dimensional integral equation is converted into a matrix equation and solved numerically. We investigate the efficiency of Gaussian quadrature in achieving the cancellation of linear and logarithmic light front infrared divergences. The vanishing energy denominator problem, which leads to severe infrared divergences in 2+1 dimensions, is investigated in detail. Our study indicates that in the context of Fock space based effective Hamiltonian methods to tackle gauge theories in 2+1 dimensions, approaches such as the similarity renormalization method may be mandatory due to uncanceled infrared divergences caused by the vanishing energy denominator problem. We define and numerically study a reduced model which is relativistic, free from infrared divergences, and exhibits logarithmic confinement. The manifestation and violation of rotational symmetry as a function of the coupling are studied quantitatively.

  14. Investigation and characterization of constraint effects on flaw growth during fatigue loading of composite materials

    NASA Technical Reports Server (NTRS)

    Stinchcomb, W. W.; Reifsnider, K. L.; Yeung, P.; Gibbins, M. N.

    1979-01-01

    An investigative program is presented in an attempt to add to the current understanding of constraint effects on the response of composite materials under cyclic loading. The objectives were: (1) to use existing data and to develop additional data in order to establish an understanding and quantitative description of flaw growth in unidirectional lamina under cyclic loading at different load direction to fiber direction angles; (2) to establish a similar understanding and description of flaw growth in lamina which are embedded in laminates between other unflawed lamina; (3) to determine the nature of the influence of constraint on flaw growth by quantitatively comparing the results of the tests; and (4) to develop a model and philosophy of constraints effects based on our investigative results.

  15. An in vitro investigation of the effect of some analgesics on human enamel.

    PubMed

    McNally, L M; Barbour, M E; O'Sullivan, D J; Jagger, D C

    2006-07-01

    The sale of over-the-counter pain relief medication has increased dramatically in recent years, and typically amounts to several hundred thousands of pounds per year in the UK. Many soluble analgesic preparations contain citric acid, and it has been suggested that these formulations may cause dental erosion. The aim of this study was to investigate the effect of some over-the-counter analgesics on tooth surface loss from human enamel. Six commonly available analgesics were chosen for this study and the effect of immersing unerupted human enamel was examined using non-contact optical profilometry. Two of the six analgesics investigated caused no detectable erosion (Boots soluble aspirin and Anadin Extra). Three caused statistically significant enamel erosion, but this was very slight and is thought to be clinically insignificant (Alka Seltzer, Panadol and Solpadeine). Only one analgesic caused possible potentially clinical significant enamel erosion. Further studies are needed to determine whether Aspro causes clinically significant enamel erosion. PMID:16774512

  16. Chemical investigation and effects of the tea of Passiflora alata on biochemical parameters in rats.

    PubMed

    Doyama, J T; Rodrigues, H G; Novelli, E L B; Cereda, E; Vilegas, W

    2005-01-15

    Passiflora alata (Passifloraceae) is a native plant from the South-America tropical forest that provides a much appreciated fruit known as "maracujá-doce". Although tea of the leaves of Passiflora alata is used in folk medicine as a sedative and tranquilizer, there are no investigations about its effects on biochemical parameters in blood or from its major chemical composition. The purpose of this study was to evaluate the effects of the tea of the leaves of Passiflora alata on biochemical parameters (antioxidant system, glucose and cholesterol levels) and to perform a phytochemical investigation of the tea. We isolated and identified two saponins and five C-glycosylflavones derived from apigenin, luteolin and chrysoeriol. Three of them are new in this species. Passiflora alata extract was administrated orally in rats at dose of 1000 mg/kg and it was observed an increase in high-density lipoprotein level (HDL-cholesterol). PMID:15619554

  17. Numerical investigation of tip clearance effects on the performance of ducted propeller

    NASA Astrophysics Data System (ADS)

    Yongle, Ding; Baowei, Song; Peng, Wang

    2015-09-01

    Tip clearance loss is a limitation of the improvement of turbomachine performance. Previous studies show the Tip clearance loss is generated by the leakage flow through the tip clearance, and is roughly linearly proportional to the gap size. This study investigates the tip clearance effects on the performance of ducted propeller. The investigation was carried out by solving the Navier-Stokes equations with the commercial Computational Fluid Dynamic (CFD) code CFX14.5. These simulations were carried out to determine the underlying mechanisms of the tip clearance effects. The calculations were performed at three different chosen advance ratios. Simulation results showed that the tip loss slope was not linearly at high advance due to the reversed pressure at the leading edge. Three type of vortical structures were observed in the tip clearance at different clearance size.

  18. An Exploratory Investigation into the Effects of Adaptation in Child-Robot Interaction

    NASA Astrophysics Data System (ADS)

    Salter, Tamie; Michaud, François; Létourneau, Dominic

    The work presented in this paper describes an exploratory investigation into the potential effects of a robot exhibiting an adaptive behaviour in reaction to a child’s interaction. In our laboratory we develop robotic devices for a diverse range of children that differ in age, gender and ability, which includes children that are diagnosed with cognitive difficulties. As all children vary in their personalities and styles of interaction, it would follow that adaptation could bring many benefits. In this abstract we give our initial examination of a series of trials which explore the effects of a fully autonomous rolling robot exhibiting adaptation (through changes in motion and sound) compared to it exhibiting pre-programmed behaviours. We investigate sensor readings on-board the robot that record the level of ‘interaction’ that the robot receives when a child plays with it and also we discuss the results from analysing video footage looking at the social aspect of the trial.

  19. Investigation of laser heating effect of metallic nanoparticles on cancer treatment

    NASA Astrophysics Data System (ADS)

    Shan, G. S.; Liu, X. M.; Chen, H. J.; Yu, J. S.; Chen, X. D.; Yao, Y.; Qi, L. M.; Chen, Z. J.

    2016-07-01

    Metallic nanoparticles can be applied for hyperthermia therapy of cancer treatment to enhance the efficacy because of their high absorption rate. The absorption of laser energy by metallic nanoparticles is strongly dependent on the concentration, shape, material of nanoparticles and the wavelength of the laser. However, there is no systematic investigation on the heating effect involving different material, concentration and laser wavelength. In this paper, gold nanoparticles (AuNPs), sliver nanoparticles (AgNPs) and sliver nanowires (AgNWs) with different concentrations are heated by 450nm and 532nm wavelength laser to investigate the heating effect. The result shows that the temperature distribution of heated metallic nanoparticles is non-uniform.

  20. Investigation of Fully Three-Dimensional Helical RF Field Effects on TWT Beam/Circuit Interaction

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.

    2000-01-01

    A fully three-dimensional (3D), time-dependent, helical traveling wave-tube (TWT) interaction model has been developed using the electromagnetic particle-in-cell (PIC) code MAFIA. The model includes a short section of helical slow-wave circuit with excitation fed by RF input/output couplers, and electron beam contained by periodic permanent magnet (PPM) focusing. All components of the model are simulated in three dimensions allowing the effects of the fully 3D helical fields on RF circuit/beam interaction to be investigated for the first time. The development of the interaction model is presented, and predicted TWT performance using 2.5D and 3D models is compared to investigate the effect of conventional approximations used in TWT analyses.

  1. Thermopower as a tool to investigate many-body effects in quantum systems

    SciTech Connect

    Kristinsdóttir, L. H.; Bengtsson, J.; Reimann, S. M.; Wacker, A.; Linke, H.

    2014-08-25

    Measuring the thermopower of a confined quantum system reveals important information about its excitation spectrum. Our simulations show how this kind of transport spectroscopy is able to extract a clear signal for the onset of Wigner localization in a nanowire segment. This demonstrates that thermopower measurements provide a tool for investigating complex many-body quantum effects, which is less intrusive than the usual charge-stability diagram as no high source-drain bias is required. While the effect is most pronounced for weak tunnel coupling and low temperatures, the excited states also significantly affect the thermopower spectrum at moderate temperature, adding distinct features to the characteristic thermopower lineshape.

  2. Aerosol optical thickness from Brewer spectrophotometers and an investigation into the stray-light effect.

    PubMed

    Silva, Abel A; Kirchhoff, Volker W J H

    2004-04-20

    The Langley method has been applied to the measurements of direct solar radiation made by Brewer spectrophotometers to obtain the aerosol optical thickness (AOT) of the atmosphere in the ultraviolet-B range. In several cases the AOT increased with wavelength, which raises suspicion about the stray-light effect. To investigate the quality of the AOT measurements and the possibility of stray light, we conducted a campaign by using single- and double-monochromator Brewers. The campaign's results have shown that both Brewers' AOT values are in good agreement and that stray light is not an important effect for AOT at wavelengths above 306 nm. PMID:15119618

  3. Theoretical investigation of the inverse Faraday effect via a stimulated Raman scattering process

    NASA Astrophysics Data System (ADS)

    Popova, Daria; Bringer, Andreas; Blügel, Stefan

    2012-03-01

    We study theoretically the origin and mechanism of the ultrafast inverse Faraday effect, which is a magneto-optical effect, attracting much interest nowadays. Laser-induced subpicosecond spin dynamics in hydrogenlike systems and isolated many-electron atoms are investigated in order to get insight into this process. We show that the stimulated Raman scattering process leads to a change of the magnetic state of a system. We obtain the time evolution of the induced magnetization, its dependencies on laser properties, and the connection with the spin-orbit coupling of a system.

  4. [On the antipyretic effect of paracetamol. Clinical investigation with two different forms of application (author's transl)].

    PubMed

    Götte, R; Liedtke, R

    1978-01-01

    144 children, aged between 15 days and 12 years, suffering from febrile condition of various etiology, were treated with differentiated single doses of paracetamol (N-acetyl-p-aminophenol) in form of syrup, suppositories and a combination of syrup with the antihistamine doxylaminsuccinate. During investigation periods of four hours, applying reduced doses, the syrup application showed the same antipyretic effects as those obtained with paracetamol suppositories. When administering the combination with doxylaminsuccinate, the antipyretic effect was reduced and the psychomotoric superactivity did not improve. A control of the actual rectal dosage scheme for repetitive applications is recommended and the combination of paracetamol with sedatives is to be discussed. PMID:304522

  5. Optical investigation of effective permeability of dilute magnetic dielectrics with magnetic field

    NASA Astrophysics Data System (ADS)

    Banerjee, Ananya; Sarkar, A.

    2016-05-01

    The prime objective of this paper is to investigate the magnetic nature of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed nano-sized Gadolinium Oxide as a DMD system. The observed experimental field variation of the effective magnetic permeability is analyzed results of optical experiment. The experiment records the variation of Brewster angle of incident polarized LASER beam from the surface of developed DMD specimen with applied out of plane external magnetic field. The effective refractive index and hence relative magnetic permeability were estimated following electro-magnetic theory. The overall results obtained and agreement between theory and experiment are good.

  6. Investigating the effect of electron emission pattern on RF gun beam quality

    NASA Astrophysics Data System (ADS)

    Rajabi, A.; Shokri, B.

    2016-05-01

    Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect.

  7. Experimental and Numerical Investigations of Constraint Effect on Deformation Behavior of Tailor-Welded Blanks

    NASA Astrophysics Data System (ADS)

    Li, Yanhua; Lin, Jianping

    2015-08-01

    Tailor-welded blanks (TWBs) have been considered as a productive sheet forming method in automotive industries. However, formability of TWBs is reduced due to different properties or thicknesses of the blanks and is a challenge for manufacturing designers. The plastic capacity of TWBs is decreased even when the material and thickness are the same. The constraint effect of the laser weld (including weld and heat-affected zone) material in the forming process of similar TWBs is a key problem to be solved in the research, development and application of thin-sheet TWBs. In this paper, uniaxial tensile tests with full-field strain measurement by digital image correlation and Erichsen tests are performed to investigate the constraint effect on deformation behavior and explore the mechanism of decreasing formability of similar TWBs. In addition, finite element models are conducted under ABAQUS code to further reveal the phenomenal behavior of the constraint effect. The results of the base material and welded blanks are compared for characterizing the differences. Furthermore, in order to better understand this mechanism, theoretical and numerical investigations are employed and compared to interpret the constraint effect of laser weld on the deformation behavior of TWBs. An index is proposed to quantify the constraint effect. Results show that the constraint effect of laser weld appears in both stretch forming and drawing of TWBs. Strain paths are approaching the plane strain condition as compared to the monolithic blank due to the constraint effect. Constraint effect is a major factor affecting the formability of TWBs when the failure occurs away from the weld seam.

  8. Wind tunnel investigation of helicopter-rotor wake effects on three helicopter fuselage models

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Mineck, R. E.

    1975-01-01

    The effects of rotor wake on helicopter fuselage aerodynamic characteristics were investigated in the Langley V/STOL tunnel. Force, moment, and pressure data were obtained on three fuselage models at various combinations of windspeed, sideslip angle, and pitch angle. The data show that the influence of rotor wake on the helicopter fuselage yawing moment imposes a significant additional thrust requirement on the tail rotor of a single-rotor helicopter at high sideslip angles.

  9. A Transmission Electron Microscope Investigation of Space Weathering Effects in Hayabusa Samples

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Berger, Eve L.

    2014-01-01

    The Hayabusa mission to asteroid 25143 Itokawa successfully returned the first direct samples of the regolith from the surface of an asteroid. The Hayabusa samples thus present a special opportunity to directly investigate the evolution of asteroidal surfaces, from the development of the regolith to the study of the more complex effects of space weathering. Here we describe the mineralogy, microstructure and composition of three Hayabusa mission particles using transmission electron microscope (TEM) techniques

  10. Moessbauer spectroscopy study of the aging and tempering of high nitrogen quenched Fe-N alloys: Kinetics of formation of Fe{sub 16}N{sub 2} nitride by interstitial ordering in martensite

    SciTech Connect

    Fall, I.; Genin, J.M.R. |

    1996-08-01

    The distribution of nitrogen atoms in austenite and during the different stages of aging and tempering of martensite is studied by Moessbauer spectroscopy, X-ray diffraction, and transmission electron microscopy (TEM). Transmission Moessbauer spectroscopy (TMS) and conversion electron Moessbauer spectroscopy (CEMS) are used for studying the austenite phase where the distribution of nitrogen atoms is found to depend on the nitriding method, gas nitriding in the authors` case, or ion implantation. Conversion electron Moessbauer spectroscopy, which concerns a depth predominantly less than 200 nm, reveals a nitrogen atom distribution different from that found in the bulk by TMS. The identification and kinetics of the stages of aging and tempering of martensite are followed by TMS measurements, and the phase characterization is confirmed by X-ray diffraction and TEM. The major stages are the early ordering of nitrogen atoms, which leads to small coherent precipitates of {alpha}-Fe{sub 16}N{sub 2}; the passage by thickening to semicoherent precipitates of {alpha}-Fe{sub 16}N{sub 2}; the dissolution of {alpha}-Fe{sub 16}N{sub 2} with the concomitant formation of {gamma}-Fe{sub 4}N; and the decomposition of retained austenite by tempering. The three first stages correspond to activation energies of 95, 126, and 94 kJ/mole, respectively, consistent with the nitrogen diffusion for the first and third stages and the dislocation pipe diffusion of iron for the second.

  11. Numerical investigation of the effects of splitter blades on the cavitation performance of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhang, Y. L.; Yuan, S. Q.; Zhang, J. F.; Feng, Y. N.; Lu, J. X.

    2014-03-01

    For the centrifugal pump, additional splitter blades are sometimes necessary in order to improve the head and efficiency. On the other hand, the additional splitter blades will have effect on the cavitation performance due to the changes at the impeller inlet channel. In order to investigate this influence, three impeller schemes were proposed based on a model pump IS50-32-160, one without splitter blades and another two with splitter blades of different inlet diameters. Numerical simulations were carried out to investigate the characteristics of internal flow and the pump cavitation performances at different NPSHA with the CFD technique. The results show that the additional splitter blades will have some positive effect on the pump cavitation performance if the inlet diameter of the splitter blade is properly selected. The reason behind such improvement is that it helps to avoid the flow blocking at the impeller inlet and the vortex cavitation inside the blade passages effectively. For the pump model under our investigation, the cavitation performance reaches its best when the inlet diameter of the splitter blade is 0.725D2.

  12. Further Investigation of the Support System Effects and Wing Twist on the NASA Common Research Model

    NASA Technical Reports Server (NTRS)

    Rivers, Melissa B.; Hunter, Craig A.; Campbell, Richard L.

    2012-01-01

    An experimental investigation of the NASA Common Research Model was conducted in the NASA Langley National Transonic Facility and NASA Ames 11-foot Transonic Wind Tunnel Facility for use in the Drag Prediction Workshop. As data from the experimental investigations was collected, a large difference in moment values was seen between the experiment and computational data from the 4th Drag Prediction Workshop. This difference led to a computational assessment to investigate model support system interference effects on the Common Research Model. The results from this investigation showed that the addition of the support system to the computational cases did increase the pitching moment so that it more closely matched the experimental results, but there was still a large discrepancy in pitching moment. This large discrepancy led to an investigation into the shape of the as-built model, which in turn led to a change in the computational grids and re-running of all the previous support system cases. The results of these cases are the focus of this paper.

  13. Experimental Investigation of the Effects of Surface Conditions on Natural Convection-Driven Evaporation

    NASA Astrophysics Data System (ADS)

    Bower, S. M.; Saylor, J. R.

    2009-11-01

    Presented are the results from an experimental investigation of the effects of surface conditions at an air/water interface on transport phenomena within the context of natural convection-driven evaporation. Experiments were conducted using tanks of heated water under several different surface conditions: 1) contamination with an oleyl alcohol monolayer, 2) contamination with a stearic acid monolayer, and 3) ``clean'' or surfactant-free. These surface conditions create the following hydrodynamic boundary conditions: 1) constant elasticity, 2) no-slip, and 3) shear-free. The effect of these boundary conditions on evaporation and air-side natural convection heat transfer is presented via the power law relationships between the Sherwood and Rayleigh numbers (for evaporation) and the Nusselt and Rayleigh numbers (for natural convection heat transfer). Additionally, infrared imagery of the water surface was collected during these experiments, yielding qualitative information on the effect of these boundary conditions on the flow near the interface. Few studies exist in which the effects of surface conditions on interfacial heat and mass transfer are investigated, making this work particularly relevant.

  14. Determination of doping effects on Si and GaAs bulk samples properties by photothermal investigations

    NASA Astrophysics Data System (ADS)

    Abroug, Sameh; Saadallah, Faycel; Yacoubi, Noureddine

    2007-11-01

    The knowledge of doping effects on optical and thermal properties of semiconductors is crucial for the development of opto-electronic compounds. The purpose of this work is to investigate these effects by mirage effect technique and spectroscopic ellipsometry SE. The near gap optical spectra are obtained from photothermal signal for differently doped Si and GaAs bulk samples. However, the above bandgap absorption is determined from SE. These spectra show that absorption in the near IR increases with dopant density and also the bandgap shifts toward low energies. This behavior is due to free carrier absorption which could be obtained by subtracting phonon-assisted absorption from the measured spectrum. This carrier absorption is related to the dopant density through a semi-empirical model. We have also used the photothermal signal phase to measure the influence of doping on thermal diffusivity.

  15. Investigation of effect of solenoid magnet on emittances of ion beam from laser ablation plasma.

    PubMed

    Ikeda, Shunsuke; Romanelli, Mark; Cinquegrani, David; Sekine, Megumi; Kumaki, Masafumi; Fuwa, Yasuhiro; Kanesue, Takeshi; Okamura, Masahiro; Horioka, Kazuhiko

    2014-02-01

    A magnetic field can increase an ion current of a laser ablation plasma and is expected to control the change of the plasma ion current. However, the magnetic field can also make some fluctuations of the plasma and the effect on the beam emittance and the emission surface is not clear. To investigate the effect of a magnetic field, we extracted the ion beams under three conditions where without magnetic field, with magnetic field, and without magnetic field with higher laser energy to measure the beam distribution in phase space. Then we compared the relations between the plasma ion current density into the extraction gap and the Twiss parameters with each condition. We observed the effect of the magnetic field on the emission surface. PMID:24593624

  16. Investigation of effect of solenoid magnet on emittances of ion beam from laser ablation plasma

    NASA Astrophysics Data System (ADS)

    Ikeda, Shunsuke; Romanelli, Mark; Cinquegrani, David; Sekine, Megumi; Kumaki, Masafumi; Fuwa, Yasuhiro; Kanesue, Takeshi; Okamura, Masahiro; Horioka, Kazuhiko

    2014-02-01

    A magnetic field can increase an ion current of a laser ablation plasma and is expected to control the change of the plasma ion current. However, the magnetic field can also make some fluctuations of the plasma and the effect on the beam emittance and the emission surface is not clear. To investigate the effect of a magnetic field, we extracted the ion beams under three conditions where without magnetic field, with magnetic field, and without magnetic field with higher laser energy to measure the beam distribution in phase space. Then we compared the relations between the plasma ion current density into the extraction gap and the Twiss parameters with each condition. We observed the effect of the magnetic field on the emission surface.

  17. Investigating the effectiveness of response strategies for vulnerabilities to corruption in the chinese public construction sector.

    PubMed

    Shan, Ming; Chan, Albert P C; Le, Yun; Hu, Yi

    2015-06-01

    Response strategy is a key for preventing widespread corruption vulnerabilities in the public construction sector. Although several studies have been devoted to this area, the effectiveness of response strategies has seldom been evaluated in China. This study aims to fill this gap by investigating the effectiveness of response strategies for corruption vulnerabilities through a survey in the Chinese public construction sector. Survey data obtained from selected experts involved in the Chinese public construction sector were analyzed by factor analysis and partial least squares-structural equation modeling. Analysis results showed that four response strategies of leadership, rules and regulations, training, and sanctions, only achieved an acceptable level in preventing corruption vulnerabilities in the Chinese public construction sector. This study contributes to knowledge by improving the understanding of the effectiveness of response strategies for corruption vulnerabilities in the public construction sector of developing countries. PMID:24894336

  18. Time resolving detector systems for radiobiological investigations of effects of single heavy ions

    SciTech Connect

    Schott, J.U. ||

    1993-12-31

    The combination of the properties of Charge Coupled Devices (CCDs) as image sensor and as detector for energetic charged particles makes them unique for time resolved radiation experiments in which single particles are to be correlated either to their radiation effects in individual objects, or to their sources or origins respectively. The experimental set up for the calibration of a frame transfer CCD type VALVO NXA 1011 with heavy ions from accelerators is described. For low energetic heavy ions, the single particle effects observed in the pixels of the sensor show a fairly linear response with the Linear Energy Transfer (LET) of the particle. As an example for the application of these detector systems in radiobiology, radiation effects of single ionizing particles in the meristem of moving biological objects have been investigated.

  19. Total Dose Effects (TDE) of heavy ionizing radiation in fungus spores and plant seeds: Preliminary investigations

    NASA Technical Reports Server (NTRS)

    Kranz, A. R.; Zimmermann, M. W.; Stadler, R.; Gartenbach, K. E.; Pickert, M.

    1992-01-01

    The opportunity to compare cosmic radiation effects caused during long and short duration exposure flights in biological objects are limited until now, and data obtained so far are very rare and insufficient. Because of the very long exposure of the experiment during the Long Duration Exposure Facility (LDEF) mission (approximately 2000 days) structural changes of the hardware material can be expected which will influence its biocompatibility and, thus, will interact with the radiobiological effects. The aim of the experiment flown on LDEF was a detailed investigation of biological effects caused by cosmic radiation especially of particles of high atomic number Z and high energy. The flight hardware consisted of standard BIOSTACK containers; in these containers a special sandwich construction consisted of visual plastic detectors with seed rsp. spore layers interlocked.

  20. An experimental and analytical investigation of stall effects on flap-lag stability in forward flight

    NASA Technical Reports Server (NTRS)

    Nagabhushanam, J.; Gaonkar, Gopal H.; Mcnulty, Michael J.

    1987-01-01

    Experiments have been performed with a 1.62 m diameter hingeless rotor in a wind tunnel to investigate flap-lag stability of isolated rotors in forward flight. The three-bladed rotor model closely approaches the simple theoretical concept of a hingeless rotor as a set of rigid, articulated flap-lag blades with offset and spring restrained flap and lag hinges. Lag regressing mode stability data was obtained for advance ratios as high as 0.55 for various combinations of collective pitch and shaft angle. The prediction includes quasi-steady stall effects on rotor trim and Floquet stability analyses. Correlation between data and prediction is presented and is compared with that of an earlier study based on a linear theory without stall effects. While the results with stall effects show marked differences from the linear theory results, the stall theory still falls short of adequate agreement with the experimental data.

  1. Rheological investigations on the theoretical predicted “Poisoning” effect in bidisperse ferrofluids

    NASA Astrophysics Data System (ADS)

    Siebert, E.; Dupuis, V.; Neveu, S.; Odenbach, S.

    2015-01-01

    Interparticle interactions in ferrofluids especially the influence of small particles on the agglomeration behaviour of large particles were the topic of numerous theoretical predictions and simulations as well as of experimental investigations. In this context the "Poisoning" effect describes the decrease of the magnetoviscous effect in the presence of small particles in a bidisperse model fluid. In order to examine this effect rheological experiments have been carried out by means of a specially designed rheometer, which allows measurements under the influence of an applied magnetic field. We were able to synthesize ferrofluids with a narrow particle size distribution containing only small or large cobalt ferrite nanoparticles, which were mixed to receive various bidisperse fluid samples. With these fluids changes of the viscous behaviour in a magnetic field have been measured and compared according to their individual compositions.

  2. The effects of corporate social responsibility on employees' affective commitment: a cross-cultural investigation.

    PubMed

    Mueller, Karsten; Hattrup, Kate; Spiess, Sven-Oliver; Lin-Hi, Nick

    2012-11-01

    This study investigated the moderating effects of several Global Leadership and Organizational Behavior Effectiveness (GLOBE) cultural value dimensions on the relationship between employees' perceptions of their organization's social responsibility and their affective organizational commitment. Based on data from a sample of 1,084 employees from 17 countries, results showed that perceived corporate social responsibility (CSR) was positively related to employees' affective commitment (AC), after controlling for individual job satisfaction and gender as well as for nation-level differences in unemployment rates. In addition, several GLOBE value dimensions moderated the effects of CSR on AC. In particular, perceptions of CSR were more positively related to AC in cultures higher in humane orientation, institutional collectivism, ingroup collectivism, and future orientation and in cultures lower in power distance. Implications for future CSR research and cross-cultural human resources management are discussed. PMID:23067337

  3. Investigating Associative Learning Effects in Patients with Prodromal Alzheimer's Disease Using the Temporal Context Model.

    PubMed

    Quenon, Lisa; de Xivry, Jean-Jacques Orban; Hanseeuw, Bernard; Ivanoiu, Adrian

    2015-10-01

    The purpose of this study was to investigate associative learning effects in patients with prodromal Alzheimer's disease (prAD) by referring to the Temporal Context Model (TCM; Howard, Jing, Rao, Provyn, & Datey, 2009), in an attempt to enhance the understanding of their associative memory impairment. TCM explains fundamental effects described in classical free-recall tasks and cued-recall tasks involving overlapping word pairs (e.g., A-B, B-C), namely (1) the contiguity effect, which is the tendency to successively recall nearby items in a list, and (2) the observation of backward (i.e., B-A) and transitive associations (i.e., A-C) between items. In TCM, these effects are hypothesized to rely on contextual representation, binding and retrieval processes, which supposedly depend on hippocampal and parahippocampal regions. As these regions are affected in prAD, the current study investigated whether prAD patients would show reduced proportions of backward and transitive associations in free and cued-recall, coupled to a reduced contiguity effect in free-recall. Seventeen older controls and 17 prAD patients performed a cued-recall task involving overlapping word pairs and a final free-recall task. Proportions of backward and transitive intrusions in cued-recall did not significantly differ between groups. However, in free-recall, prAD patients demonstrated a reduced contiguity effect as well as reduced proportions of backward and transitive associations compared to older controls. These findings are discussed within the hypothesis that the contextual representation, binding and/or retrieval processes are affected in prAD patients compared to healthy older individuals. PMID:26411265

  4. Effects of video-game play on information processing: a meta-analytic investigation.

    PubMed

    Powers, Kasey L; Brooks, Patricia J; Aldrich, Naomi J; Palladino, Melissa A; Alfieri, Louis

    2013-12-01

    Do video games enhance cognitive functioning? We conducted two meta-analyses based on different research designs to investigate how video games impact information-processing skills (auditory processing, executive functions, motor skills, spatial imagery, and visual processing). Quasi-experimental studies (72 studies, 318 comparisons) compare habitual gamers with controls; true experiments (46 studies, 251 comparisons) use commercial video games in training. Using random-effects models, video games led to improved information processing in both the quasi-experimental studies, d = 0.61, 95% CI [0.50, 0.73], and the true experiments, d = 0.48, 95% CI [0.35, 0.60]. Whereas the quasi-experimental studies yielded small to large effect sizes across domains, the true experiments yielded negligible effects for executive functions, which contrasted with the small to medium effect sizes in other domains. The quasi-experimental studies appeared more susceptible to bias than were the true experiments, with larger effects being reported in higher-tier than in lower-tier journals, and larger effects reported by the most active research groups in comparison with other labs. The results are further discussed with respect to other moderators and limitations in the extant literature. PMID:23519430

  5. Investigations on the antifatigue and antihypoxic effects of Paecilomyces hepiali extract.

    PubMed

    Wang, Juan; Li, Lan Zhou; Liu, Yan Ge; Teng, Li Rong; Lu, Jia Hui; Xie, Jing; Hu, Wen Ji; Liu, Yan; Liu, Yang; Wang, Di; Teng, Le Sheng

    2016-02-01

    Paecilomyces hepiali, one of the most valuable and effective Chinese medicinal herbs, possesses potential antioxidant, immunomodulatory, antitumor and anti‑inflammatory properties. The present study aimed to investigate the antifatigue and antihypoxic effects of Paecilomyces hepiali extract (PHC) in a mouse model. Using a rotating rod, forced swimming and running assessment, the antifatigue activity of PHC was determined. PHC administration for 7 days had no effect on mouse horizontal or vertical movement, indicating no neurotoxicity at the selected doses was observed. Using a normobaric hypoxia, sodium nitrite toxicosis and acute cerebral ischemia assessments, PHC was confirmed to possess antihypoxic effects. PHC treatment for 7 days significantly enhanced the serum and liver levels of adenosine triphosphate, superoxide dismutase and glutathione peroxidase, prior to and following 60 min of swimming. The levels of antioxidant‑associated proteins in the livers of the mice were analyzed using western blotting. PHC effectively increased the expression levels of phosphorylated (p)‑5'‑monophosphate (AMP)‑activated protein kinase (AMPK), p‑protein kinase B (AKT) and p‑mammalian target of rapamycin (mTOR). The results of the present study demonstrated that PHC efficiently enhanced endurance from fatigue and had antihypoxic effects through elevation of the antioxidant capacity in the serum and liver, at least in part through the AMPK and AKT/mTOR pathways. These results indicate the potential of this natural product as an antioxidant in the treatment of fatigue, hypoxia and their associated diseases. PMID:26717979

  6. New PANDA Tests to Investigate Effects of Light Gases on Passive Safety Systems

    SciTech Connect

    Paladino, D.; Auban, O.; Candreia, P.; Huggenberger, M.; Strassberger, H.J.

    2002-07-01

    The large- scale thermal-hydraulic PANDA facility (located at PSI in Switzerland), has been used over the last few years for investigating different passive decay- heat removal systems and containment phenomena for the next generation of light water reactors (Simplified Boiling Water Reactor: SBWR; European Simplified Boiling Water Reactor: ESBWR; Siedewasserreaktor: SWR-1000). Currently, as part of the European Commission 5. EURATOM Framework Programme project 'Testing and Enhanced Modelling of Passive Evolutionary Systems Technology for Containment Cooling' (TEMPEST), a new series of tests is being planned in the PANDA facility to experimentally investigate the distribution of non-condensable gases inside the containment and their effect on the performance of the 'Passive Containment Cooling System' (PCCS). Hydrogen release caused by the metal-water reaction in the case of a postulated severe accident will be simulated in PANDA by injecting helium into the reactor pressure vessel. In order to provide suitable data for Computational Fluid Dynamic (CFD) code assessment and improvement, the instrumentation in PANDA has been upgraded for the new tests. In the present paper, a detailed discussion is given of the new PANDA tests to be performed to investigate the effects of light gas on passive safety systems. The tests are scheduled for the first half of the year 2002. (authors)

  7. Spectroscopic investigation of the constituent components effect on the biodegradable package characteristics

    NASA Astrophysics Data System (ADS)

    Coťa, C.; Cioica, N.; Filip, C.; Fechete, R.; Todica, M.; Nagy, E. M.; Cozar, O.

    2015-12-01

    The effect of the nature and the content of the plasticizers (water, glycerol) on the corn starch based biodegradable packages properties (crystalline-amorphous) and also on their degradation process after absorption of distilled water were investigated by 1H NMR relaxation and 13C CP/MAS NMR spectroscopies. For this goal, a set of 14 samples with various starch/glycerol/water (mass %) ratios were prepared and investigated after extrusion process in order to establish their crystalline or amorphous character. The composition having starch/glycerol/water 68/17/15 mass % ratio was found to have a dominant amorphous character and very similar features with a commercial specimen (USA) used for the package. It was also found that this best package is extremely degraded after just one day under water absorption. The most resistant package was that with a large content of starch (78/19.5/2.5).

  8. Large object investigation by digital holography with effective spectrum multiplexing under single-exposure approach

    SciTech Connect

    Liu, Ning Zhang, Yingying; Xie, Jun

    2014-10-13

    We present a method to investigate large object by digital holography with effective spectrum multiplexing under single-exposure approach. This method splits the original reference beam and redirects one of its branches as a second object beam. Through the modified Mach-Zehnder interferometer, the two object beams can illuminate different parts of the large object and create a spectrum multiplexed hologram onto the focal plane array of the charge-coupled device/complementary metal oxide semiconductor camera. After correct spectrum extraction and image reconstruction, the large object can be fully observed within only one single snap-shot. The flexibility and great performance make our method a very attractive and promising technique for large object investigation under common 632.8 nm illumination.

  9. Atomic scale investigations of the gate controlled tunneling effect in graphyne nanoribbon

    SciTech Connect

    Yang, Wen; Wang, Lu-Hao; Geng, Yang; Sun, Qing-Qing E-mail: pengzhou@fudan.edu.cn; Zhou, Peng E-mail: pengzhou@fudan.edu.cn; Ding, Shi-Jing; Wei Zhang, David

    2013-12-14

    Configuration and transport properties of zigzag graphyne nanoribbon (n = 2) are investigated by means of the first-principles calculations and non-equilibrium Green's function in this work. We demonstrated the controllability of the graphyne's conductivity by gate bias, and the tunneling behavior induced by gate and drain voltages was investigated systemically. The characteristics of I{sub d}-V{sub d}, I{sub d}-V{sub g}, as well as the evolutions of current with electron temperature elevation were explored. The device exhibits a tunneling ratio around 10{sup 3}, and the state art of tunneling operations of the tunneling field effect transistor in this split-new material was achieved.

  10. Experimental investigation of the effects of high-frequency electroactive morphing on the shear-layer

    NASA Astrophysics Data System (ADS)

    Scheller, Johannes; Rizzo, Karl-Joseph; Jodin, Gurvan; Duhayon, Eric; Rouchon, Jean-François; Hunt, Julian; Braza, Marianna

    2015-11-01

    Time-resolved PIV measurements are conducted at a Reynolds number of 270 . 000 downstream of the trailing edge of a NACA4412 airfoil equipped with trailing-edge piezoelectric tab actuators to investigate the high-frequency low-amplitude actuation's effect on the shear-layer. A comparison of the time-averaged Reynolds stress tensor components at different actuation frequency reveals a significant impact of the actuation on the shear-layer dynamics. A proper orthogonal decomposition analysis is conducted in order to investigate the actuation's impact on the vortex breakdown. It will be shown that a specific low-amplitude actuation frequency enables a reduction of the predominant shear-layer frequencies.

  11. Spectroscopic investigation of the constituent components effect on the biodegradable package characteristics

    SciTech Connect

    Coţa, C.; Cioica, N. Nagy, E. M.; Filip, C.; Fechete, R.; Todica, M.; Cozar, O.

    2015-12-23

    The effect of the nature and the content of the plasticizers (water, glycerol) on the corn starch based biodegradable packages properties (crystalline-amorphous) and also on their degradation process after absorption of distilled water were investigated by {sup 1}H NMR relaxation and {sup 13}C CP/MAS NMR spectroscopies. For this goal, a set of 14 samples with various starch/glycerol/water (mass %) ratios were prepared and investigated after extrusion process in order to establish their crystalline or amorphous character. The composition having starch/glycerol/water 68/17/15 mass % ratio was found to have a dominant amorphous character and very similar features with a commercial specimen (USA) used for the package. It was also found that this best package is extremely degraded after just one day under water absorption. The most resistant package was that with a large content of starch (78/19.5/2.5)

  12. Investigation on the effect of aperture sizes and receiver positions in coupled rooms.

    PubMed

    Xiang, Ning; Escolano, Jose; Navarro, Juan M; Jing, Yun

    2013-06-01

    Some recent concert hall designs have incorporated coupled reverberation chambers to the main hall that have stimulated a range of research activities in architectural acoustics. The coupling apertures between two or more coupled-volume systems are of central importance for sound propagation and sound energy decays throughout the coupled-volume systems. In addition, positions of sound sources and receivers relative to the aperture also have a profound influence on the sound energy distributions and decays. This work investigates the effect of aperture size on the behavior of coupled-volume systems using both acoustic scale-models and diffusion equation models. In these physical and numerical models, the sound source and receiver positions relative to the aperture are also investigated. Through systematic comparisons between results achieved from both physical scale models and numerical models, this work reveals valid ranges and limitations of the diffusion equation model for room-acoustic modeling. PMID:23742351

  13. Investigation of the thickness effect to impedance analysis results AlGaN acoustic sensor

    NASA Astrophysics Data System (ADS)

    Özen, Soner; Bilgiç, Eyüp; Gülmez, Gülay; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan; Mohammadigharehbagh, Reza

    2016-03-01

    In this study, AlGaN acoustic sensors were deposited on aluminum metal substrate by thermionic vacuum arc (TVA) method, for the first time. Impedance analyses of the fabricated acoustic sensors were investigated for the determining of effect of the nano layer thickness. Thickness values are very close to each others. Fabricated sensors have been fabricated from AlGaN deposited on aluminum substrates. Gallium materials are used in many applications for optoelectronic device and semiconductor technology. Thermionic vacuum arc is the deposition technology for the variously materials and applications field. TVA production parameters and some properties of the deposited layers were investigated. TVA is the fast deposition technology for the gallium compounds and doped gallium compounds. Obtained results that AlGaN layer are very promising material for an acoustic sensor but also TVA is proper fast technology for the production.

  14. A rheometer dedicated for the investigation of viscoelastic effects in commercial magnetic fluids

    NASA Astrophysics Data System (ADS)

    Odenbach, Stefan; Rylewicz, Thomas; Heyen, Michael

    1999-07-01

    The investigation of viscoelastic properties of commercial ferrofluids based on nanosized magnetite particles in various carrier liquids requires a dedicated rheometer allowing the detection of extremely small changes in viscous and viscoelastic properties. The observation of magnetoviscoelastic behavior in commercial ferrofluids may become particularly important since they exhibit long-term stability allowing reproducibility of the experiments. In addition, they are of relatively simple composition reducing the problems in theoretical description of the observed effects. We will present here the design and main performance data of a rheometer developed for the kind of investigations mentioned above. The quality of the performance will be demonstrated with some new data on rheological properties of a commercial ferrofluid.

  15. Wind tunnel investigation of the effect of high relative velocities on the structural integrity of birds

    NASA Technical Reports Server (NTRS)

    Bresnahan, D. L.

    1972-01-01

    An experimental investigation was conducted in a supersonic wind tunnel to determine the effect a sudden high velocity headwind had on the physical deformation and structural breakup characteristics of birds. Several sizes of recently killed birds were dropped into the test section at free-stream Mach numbers ranging from 0.2 to 0.8 and photographed with high-speed motion-picture cameras. These conditions simulated flow conditions encountered when birds are ingested into the inlets of high speed aircraft, thereby constituting a safety hazard to the aircraft and its occupants. The investigation shows that, over the range of headwind conditions tested, the birds remained structurally intact and did not suffer any appreciable deformation or structural breakup.

  16. Dissipative effects in fission investigated with proton-on-lead reactions

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Taïeb, J.; Álvarez-Pol, H.; Audouin, L.; Ayyad, Y.; Bélier, G.; Boutoux, G.; Casarejos, E.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelić-Heil, A.; Laurent, B.; Martin, J.-F.; Paradela, C.; Pellereau, E.; Pietras, B.; Ramos, D.; Rodríguez-Tajes, C.; Rossi, D. M.; Simon, H.; Vargas, J.; Voss, B.

    2016-05-01

    The complete kinematic measurement of the two fission fragments permitted us to investigate dissipative effects at large deformations, between the saddle-point and the corresponding scission configurations. Up to now, this kind of study has only been performed with fusionfission reactions using a limited number of observables, such as the mass distribution of the fission fragments or the neutron multiplicities. However, the large angular momenta gained by the compound nucleus could affect the conclusions drawn from such experiments. In this work, the use of spallation reactions, where the fissioning systems are produced with low angular momentum, small deformations and high excitation energies, favors the study of dissipation, and allowed us to define new observables, such as postscission neutron multiplicities and the neutron excess of the final fission fragments as a function of the atomic number of the fissioning system. These new observables are used to investigate the dissipation at large deformations.

  17. Aerosol effects over China investigated with a high resolution convection permitting weather model

    NASA Astrophysics Data System (ADS)

    Pagh Nielsen, Kristian; Mahura, Alexander; Yang, Xiaohua

    2016-04-01

    We investigate aerosol effects in the operational high resolution (2.5 km) convection permitting non-hydrostatical weather model HARMONIE (HIRLAM-ALADIN Regional Mesoscale Operational NWP in Euromed). Aerosol input from the global C-IFS model is downscaled and used. The impact of using realistic aerosols on both the direct and the indirect aerosol effects is studied and compared with default simulations that include only the direct aerosol effect of climatological aerosols. The study is performed as a part of the MarcoPolo FP7 project for a selected region of China during the months January and July 2010, where in particular January 2010 saw several cases of high anthropogenic aerosol loads. We also investigate the impact of accounting for realistic aerosol single scattering albedos and asymmetry factors in the simulations of the direct aerosol forcing. In many studies only variations in the aerosol optical depth are accounted for. We show this to be inadequate, when the assumed aerosol types have different optical properties than the actual aerosols.

  18. Investigation of the long-term effects of unilateral hearing loss in adults.

    PubMed

    Colletti, V; Fiorino, F G; Carner, M; Rizzi, R

    1988-05-01

    The recent audiological literature has put forward the hypothesis that children with unilateral hearing loss (UHL) show delays in educational achievement and academic progress and some behavioural difficulties. This motivated us to investigate the long-term effects of monaural auditory deprivation in a group of adults who had suffered from UHL since childhood. A group of subjects, ranging in age from 30 to 55 years, suffering from sensorineural UHL since early childhood, has been examined for psychosocial and psychoacoustical effects and statistically compared with a control group matched for age and sex. We prepared a questionnaire directed to provide some objective and subjective indices of psychosocial disability and handicap. Some questions were directed towards specific aspects of auditory function; others assessed the degree of education and the type of working performed. The results of the investigation confirmed the superiority of binaural v. monaural hearing. This was clearly demonstrated in psycho-acoustical performance in sound localisation, speech recognition in noise, together with the appreciation of music. On the other hand, the parameters concerned with educational, social and employment achievement did not support the existence of any significant difference between binaurally and monaurally hearing subjects. The data obtained in the present study thus do not support the existence of non-auditory, long-term effects of monaural hearing loss. PMID:3390628

  19. The influence of surface effects on the hydrogen absorption investigated on the V H model system

    NASA Astrophysics Data System (ADS)

    Müller, K.-H.; Paulus, H.; Kiss, G.

    2001-07-01

    The system V-O-H has been chosen as a model system to investigate surface effects on hydrogen absorption in metals. By means of XPS, SIMS, and thermal desorption mass spectrometry (TDMS) methods, the influence of oxygen segregated from the bulk as well as adsorbed from the gas phase has been pointed out. Segregated oxygen obstructs the hydrogen absorption, whereas non-stoichiometric and stoichiometric oxides have a preventing effect already with coverages in the range of monolayers. Ion bombardment in connection with sputter-cleaning or SNMS and SIMS analyses produces additional absorption sites in the surface near region for hydrogen. These can be populated by hydrogen from the gas phase during H 2 exposure or diffusing from the bulk, if the sample was H 2 loaded before. Beside elements like vanadium, there exist alloys (e.g. TiFe, LaNi 5, TiMn 2), which are particularly suitable for practical storage purposes. It is important for the further development of such alloys but also for a better understanding of absorption kinetics to investigate the influence of surface effects also on these alloys.

  20. Experimental investigations of driving frequency effect in low-pressure capacitively coupled oxygen discharges

    SciTech Connect

    Liu, Jia; Liu, Yong-Xin; Liu, Gang-Hu; Gao, Fei; Wang, You-Nian

    2015-04-14

    The effect of driving frequency on the electron density is investigated in low-pressure capacitively coupled oxygen plasmas by utilizing a floating hairpin probe. The power absorbed by the plasma is investigated and it is found that the power lost in the matching network can reach 50% or higher under certain conditions. The effect of driving frequency on the electron density is studied from two aspects, i.e., constant absorbed power and electrode voltage. In the former case, the electron density increases with the driving frequency increasing from 13.56 to 40.68 MHz and slightly changes depending on the gas pressures with the frequency further increasing to 100 MHz. In the latter case, the electron density rapidly increases when the driving frequency increases from 13.56 to 40.68 MHz, and then decreases with the frequency further increasing to 100 MHz. The electron series resonance is observed at 40.68 MHz and can be attributed to the higher electron density. And the standing wave effect also plays an important role in increasing electron density at 100 MHz and 2.6 Pa.

  1. Experimental investigations of driving frequency effect in low-pressure capacitively coupled oxygen discharges

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Liu, Yong-Xin; Liu, Gang-Hu; Gao, Fei; Wang, You-Nian

    2015-04-01

    The effect of driving frequency on the electron density is investigated in low-pressure capacitively coupled oxygen plasmas by utilizing a floating hairpin probe. The power absorbed by the plasma is investigated and it is found that the power lost in the matching network can reach 50% or higher under certain conditions. The effect of driving frequency on the electron density is studied from two aspects, i.e., constant absorbed power and electrode voltage. In the former case, the electron density increases with the driving frequency increasing from 13.56 to 40.68 MHz and slightly changes depending on the gas pressures with the frequency further increasing to 100 MHz. In the latter case, the electron density rapidly increases when the driving frequency increases from 13.56 to 40.68 MHz, and then decreases with the frequency further increasing to 100 MHz. The electron series resonance is observed at 40.68 MHz and can be attributed to the higher electron density. And the standing wave effect also plays an important role in increasing electron density at 100 MHz and 2.6 Pa.

  2. Investigation of deuterated target effects on neutron yield in plasma focus device SBUMTPF1

    NASA Astrophysics Data System (ADS)

    Shahbazi Rad, Zahra; Abbasi Davani, Fereydoun; Shirani, Babak

    2015-04-01

    In this research, the effect of inserting deuterated solid target in plasma focus device `SBUMTPF1' on neutron yield has been investigated. The deuterated target with the diameter of 2.5 cm was placed at different heights relative to the anode tip. In each height, the best place of target (where the ion density is highest) was found from observing the effects of ions struck on the aluminum samples. Also for each height, 20 shots were performed at the optimum pressure of deuterium working gas and operating voltage, which are equal to 1.5 mbar and 24 kV, respectively. The neutron production was measured with two activation counters, which placed in 0○ and 90○ relative to the anode axis. Neutron scattering from two activation counters was calculated with MCNP4C code and the results showed that this effect is negligible. In this article, the probability of implanting deuterium ions into the titanium target was also investigated. Deviation angle of the ion emission relative to the anode axis was measured experimentally in this research and it was about 3.1○.

  3. Investigation about decoupling capacitors of PMT voltage divider effects on neutron-gamma discrimination

    SciTech Connect

    Divani, Nazila Firoozabadi, Mohammad M.; Bayat, Esmail

    2014-11-24

    Scintillators are almost used in any nuclear laboratory. These detectors combine of scintillation materials, PMT and a voltage divider. Voltage dividers are different in resistive ladder design. But the effect of decoupling capacitors and damping resistors haven’t discussed yet. In this paper at first a good equilibrium circuit designed for PMT, and it was used for investigating about capacitors and resistors in much manner. Results show that decoupling capacitors have great effect on PMT output pulses. In this research, it was tried to investigate the effect of Capacitor’s value and places on PMT voltage divider in Neutron-Gamma discrimination capability. Therefore, the voltage divider circuit for R329-02 Hamamatsu PMT was made and Zero Cross method used for neutron-gamma discrimination. The neutron source was a 20Ci Am-Be. Anode and Dynode pulses and discrimination spectrum were saved. The results showed that the pulse height and discrimination quality change with the value and setting of capacitors.

  4. Investigation of the dominant positive effect of porcine farnesoid X receptor (FXR) splice variant 1.

    PubMed

    Gray, Matthew A; James Squires, E

    2015-04-10

    Pigs are well recognized as a model for humans in research studies due to similarities in metabolism and physiology between the two species. The potential for pigs to model humans in studying metabolic diseases is highly dependent on similarities in hepatic metabolism between the two species, including similarities in the farnesoid X receptor (FXR; NR1H4) which regulate bile acid homeostasis. During initial cloning of porcine FXR (pFXR), an alternative splice variant (pFXR-SV1) was isolated which contained a four amino acid (MYTG) insert that exerted a dominant positive effect on the wild type receptor (pFXR-WT). The current study investigated the role of this insert in the dominant positive effect. Individual point mutations were made to the first three amino acids of the MYTG insert. Mutations of the methionine (M) or threonine (T) to alanine (A) reduced the dominant positive effect, while mutation of the tyrosine (Y) to either A or phenylalanine (F) completely abolished the dominant positive effect. Treatment with the tyrosine phosphatase inhibitor sodium orthovanadate (Na3VO4) increased the dominant positive effect of pFXR-SV1 by about 30%. These results suggest that the dominant positive effect may be dependent on the phosphorylation status of the tyrosine in the MYTG insert. The human variant hFXRα+ has the same MYTG insert as pFXR-SV1, but did not cause a dominant positive effect on hFXR-WT and significantly reduced the activity of hFXR-WT. Thus, although the MYTG insert is conserved in both human and pig, the effects of this insert are different in the two species. PMID:25623328

  5. Moessbauer spectroscopy study of iron-based catalysts used in Fischer-Tropsch synthesis

    SciTech Connect

    Rao, K.R.P.M.; Huggins, F.E.; Huffman, G.P.

    1995-12-01

    Mossbauer investigations of iron-based catalysts containing the promoters K, and Cu, and binders consisting of oxides of Al, Si and Zr were carried out. Catalysts subjected to pretreatment in gas atmospheres containing mixtures of CO, H{sub 2}, and He have been studied. It is shown that the nature of binders, promoters and pretreatment of a catalyst influence the iron-phases formed during pretreatment and FT synthesis. Activation of the catalysts in CO leads to rapid and almost complete formation of {chi}-Fe{sub 5}C{sub 2} during activation and gives rise to high (H{sub 2}+CO) conversion. On the other hand, activation of the catalysts in synthesis gas leads to slow and incomplete formation of carbides and low (H{sub 2}+CO) conversion.

  6. Effect of emodin on Candida albicans growth investigated by microcalorimetry combined with chemometric analysis.

    PubMed

    Kong, W J; Wang, J B; Jin, C; Zhao, Y L; Dai, C M; Xiao, X H; Li, Z L

    2009-07-01

    Using the 3114/3115 thermal activity monitor (TAM) air isothermal microcalorimeter, ampoule mode, the heat output of Candida albicans growth at 37 degrees C was measured, and the effect of emodin on C. albicans growth was evaluated by microcalorimetry coupled with chemometric methods. The similarities between the heat flow power (HFP)-time curves of C. albicans growth affected by different concentrations of emodin were calculated by similarity analysis (SA). In the correspondence analysis (CA) diagram of eight quantitative parameters taken from the HFP-time curves, it could be deduced that emodin had definite dose-effect relationship as the distance between different concentrations of it increased along with the dosage and the effect. From the principal component analysis (PCA) on eight quantitative parameters, the action of emodin on C. albicans growth could be easily evaluated by analyzing the change of values of the main two parameters, growth rate constant k (2) and maximum power output P(2)(m). The coherent results of SA, CA, and PCA showed that emodin at different concentrations had different effects on C. albicans growth metabolism: A low concentration (0-10 microg ml(-1)) poorly inhibited the growth of C. albicans, and a high concentration (15-35 microg ml(-1)) could notably inhibit growth of this fungus. This work provided a useful idea of the combination of microcalorimetry and chemometric analysis for investigating the effect of drug and other compounds on microbes. PMID:19543891

  7. Changes in quartz solubility and porosity due to effective stress: An experimental investigation of pressure solution

    SciTech Connect

    Elias, B.P.; Hajash, A. Jr. )

    1992-05-01

    Experimental compaction of quartz sand was conducted in semistatic flow-through systems at 150C to examine the chemical and physical processes associated with pressure solution. Pore-fluid chemistry and porosity were monitored through time to investigate the role of effective stress on silica solubility and compaction rate. The concentration of silica in the pore fluid varied directly with effective stress at constant pore-fluid pressure, but not in a linear fashion. Increases in silica were not transient and could be partially reversed by removal of the effective stress. Porosity decreased steadily under constant nonzero effective stress at 150C, but remained essentially constant under identical loading conditions at room temperature. Initial compaction rates increased linearly with effective stress. Deformed samples show indented contacts with fractures and dissolution features, healed microfractures, and a decrease in average grain size. Multiple mechanisms (pressure solution, subcritical crack growth, crack healing) appear to operate at grain contacts during compaction. The authors interpret long-term, time-dependent compaction accompanied by stress-induced changes in fluid chemistry as evidence for pressure solution.

  8. Finite element modelling for the investigation of edge effect in acoustic micro imaging of microelectronic packages

    NASA Astrophysics Data System (ADS)

    Shen Lee, Chean; Zhang, Guang-Ming; Harvey, David M.; Ma, Hong-Wei; Braden, Derek R.

    2016-02-01

    In acoustic micro imaging of microelectronic packages, edge effect is often presented as artifacts of C-scan images, which may potentially obscure the detection of defects such as cracks and voids in the solder joints. The cause of edge effect is debatable. In this paper, a 2D finite element model is developed on the basis of acoustic micro imaging of a flip-chip package using a 230 MHz focused transducer to investigate acoustic propagation inside the package in attempt to elucidate the fundamental mechanism that causes the edge effect. A virtual transducer is designed in the finite element model to reduce the coupling fluid domain, and its performance is characterised against the physical transducer specification. The numerical results showed that the under bump metallization (UBM) structure inside the package has a significant impact on the edge effect. Simulated wavefields also showed that the edge effect is mainly attributed to the horizontal scatter, which is observed in the interface of silicon die-to-the outer radius of solder bump. The horizontal scatter occurs even for a flip-chip package without the UBM structure.

  9. Investigation of Factors Determining the Enhanced Permeability and Retention Effect in Subcutaneous Xenografts.

    PubMed

    Bolkestein, Michiel; de Blois, Erik; Koelewijn, Stuart J; Eggermont, Alexander M M; Grosveld, Frank; de Jong, Marion; Koning, Gerben A

    2016-04-01

    Liposomal chemotherapy offers several advantages over conventional therapies, including high intratumoral drug delivery, reduced side effects, prolonged circulation time, and the possibility to dose higher. The efficient delivery of liposomal chemotherapeutics relies, however, on the enhanced permeability and retention (EPR) effect, which refers to the ability of macromolecules to extravasate leaky tumor vessels and accumulate in the tumor tissue. Using a panel of human xenograft tumors, we evaluated the influence of the EPR effect on liposomal distribution in vivo by injection of pegylated liposomes radiolabeled with(111)In. Liposomal accumulation in tumors and organs was followed over time by SPECT/CT imaging. We observed that fast-growing xenografts, which may be less representative of tumor development in patients, showed higher liposomal accumulation than slow-growing xenografts. Additionally, several other parameters known to influence the EPR effect were evaluated, such as blood and lymphatic vessel density, intratumoral hypoxia, and the presence of infiltrating macrophages. The investigation of various parameters showed a few correlations. Although hypoxia, proliferation, and macrophage presence were associated with tumor growth, no hard conclusions or predictions could be made regarding the EPR effect or liposomal uptake. However, liposomal uptake was significantly correlated with tumor growth, with fast-growing tumors showing a higher uptake, although no biological determinants could be elucidated to explain this correlation. PMID:26719375

  10. Investigation of collisional effects within the bending magnet region of a DIII-D neutral beamline

    SciTech Connect

    Kessler, D.N.; Hong, R.; Kellman, D.H.

    1993-10-01

    The region between the pole faces of the DIII-D neutral beamline residual ion bending magnets is an area of transient high gas pressure which may cause beam defocusing and increased heating of beamline internal components due to collisional effects. An investigation of these effects helps in understanding residual ion trajectories and in providing information for studying in the beamline capability for operation with increased pulse duration. Examination of collisional effects, and of the possible existence of space charge blow-up, was carried out by injecting deuterium gas into the region between the magnet pole faces with rates varying from 0 to 18 torr-{ell}/sec. Thermocouple and waterflow calorimetry data were taken to measure the beamline component heating and beam powder deposition on the magnet pole shields, magnet louvers, ion dump, beam collimators, and calorimeter. Data was also taken at gas flow rates varying from 0 to 25 torr-{ell}/sec into the neutralizer cell and is compared with the magnet region gas injection data obtained. Results show that both collisional effects and space charge blow-up play a role in magnet region component heating and that neutralizer gas flow sufficiently reduces component heating without incurring unacceptable power losses through collisional effects.

  11. An Experimental Investigation of Sting-Support Effects on Drag and a Comparison with Jet Effects at Transonic Speeds

    NASA Technical Reports Server (NTRS)

    Cahn, Maurice S.

    1956-01-01

    This paper presents the results of an investigation of sting-support interference on afterbody drag at transonic speeds. Stings with varying diameter, cone angle, and cylindrical length were tested at the rea r of a model with various afterbody shapes. The data were obtained at an angle of attack of O deg. and at Mach numbers from 0.80 to 1.10. It was found that, in general, the addition of a sting caused a drag reduction. A method is presented whereby approximate sting-interferen ce corrections may be made to models with afterbodies and sting suppo rts of similar size and scale to those of this paper provided the bou ndary layer is turbulent at the model base and the Reynolds numbers a re of the same order of magnitude. Reynolds number of the tests prese nted varied from 15.0 x 10 (exp 6) to 17.4 x 10 (exp 6) based on body length. Sting effects from this investigation are compared with data of jet effects on the same afterbodies. The results of this comparis on indicate that for the more gradually contoured afterbodies, a stin g shape can be found which will duplicate the jet effects, but that f or blunt afterbodies no solid sting shape will duplicate the jet effe cts.

  12. Investigation of Seal-to-Floor Effects on Semi-Span Transonic Models

    NASA Technical Reports Server (NTRS)

    Sleppy, Mark A.; Engel, Eric A.; Watson, Kevin T.; Atler, Douglas M.

    2009-01-01

    In an effort to achieve the maximum possible Reynolds number (Re) when conducting production testing for flight loads aerodynamic databases, it has been the preferred practice of The Boeing Company / Commercial Airplanes (BCA) -- Loads and Dynamics Group since the early 1990's to test large scale semi-span models in the 11- By 11-Foot Transonic Wind Tunnel (TWT) leg of the Unitary Plan Wind Tunnel (UPWT) at the NASA Ames Research Center (ARC). There are many problems related to testing large scale semi-span models of high aspect ratio flexible transport wings, such as; floor boundary layer effects, wing spanwise wall effects, solid blockage buoyancy effects, floor mechanical interference effects, airflow under the model effects, or tunnel flow gradient effects. For most of these issues, BCA has developed and implemented either standard testing methods or numerical correction schemes and these will not be discussed in this document. Other researchers have reported on semi-span transonic testing correction issues, however most of the reported research has been for low Mach testing. Some of the reports for low Mach testing address the difficult problem of preventing undesirable airflow under a semi-span model while ensuring unrestricted main balance functionality, however, for transonic models this issue has gone unresolved. BCA has been cognizant for sometime that there are marked differences in wing pressure distributions from semi-span transonic model testing than from full model or flight testing. It has been suspected that these differences are at least in part due to airflow under the model. Previous efforts by BCA to address this issue have proven to be ineffective or inconclusive and in one situation resulted in broken hardware. This paper reports on a Boeing-NASA collaborative investigation based on a series of small tests conducted between June 2006 and November 2007 in the 11 by 11 foot Transonic Wind Tunnel at NASA Ames on three large commercial jet

  13. In vitro investigation of eddy current effect on pacemaker operation generated by low frequency magnetic field.

    PubMed

    Babouri, A; Hedjeidj, A

    2007-01-01

    This paper presents in vitro investigation of the eddy current induction effects to the cardiac pacemaker exposed to low frequency magnetic fields. The method used in this study is based to the interaction by inductive coupling through the loop formed by the pacemaker and its leads and the surrounding medium. This interaction results in an induced electromotive force between the terminals of the pacemaker which can potentially disturb the operation of this last. In this article we present experimental results, analytical calculations and numerical simulations using the finite element method. PMID:18003302

  14. Investigation of defect-induced abnormal body current in fin field-effect-transistors

    SciTech Connect

    Liu, Kuan-Ju; Tsai, Jyun-Yu; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Yang, Ren-Ya; Cheng, Osbert; Huang, Cheng-Tung

    2015-08-24

    This letter investigates the mechanism of abnormal body current at the linear region in n-channel high-k/metal gate stack fin field effect transistors. Unlike body current, which is generated by impact ionization at high drain voltages, abnormal body current was found to increase with decreasing drain voltages. Notably, the unusual body leakage only occurs in three-dimensional structure devices. Based on measurements under different operation conditions, the abnormal body current can be attributed to fin surface defect-induced leakage current, and the mechanism is electron tunneling to the fin via the defects, resulting in holes left at the body terminal.

  15. Numerical investigation on the effects of EGR on CI engine characteristics using soyabean biodiesel

    NASA Astrophysics Data System (ADS)

    Datta, Ambarish; Mandal, Bijan Kumar

    2016-07-01

    In this work an attempt has been made to numerically investigate the effect of soyabean biodiesels on an unmodified CI engine and then to study and reduce the NOx emission by the introduction of exhaust gas recirculation (EGR) technique at the rates of 10% and 20%. Compared to no EGR condition for the neat biodiesel, the NOx emission is reduced by 44% and 70% with 10% and 20% EGR respectively. But the increase in the EGR rate deteriorates the engine performance and increases the emissions, other than NOx. Thus, EGR helps in reducing NOx emission but its rate of introduction has to be bounded by a limit.

  16. Effect of Cu content on the defect evolution in Fe-Cu alloys investigated by PALS

    NASA Astrophysics Data System (ADS)

    Cao, X. Z.; Lai, X.; Cheng, G. D.; Jin, S. X.; Zhang, X.; Zhang, P.; Wang, B. Y.

    2016-01-01

    The effect of Cu content on the evolution of defects in Fe-x%Cu alloys (x= 0.15, 0.3, and 0.6) were investigated using Positron Annihilation Lifetime Spectroscopy (PALS). The vacancy-type and Cu-vacancy complexes defects were respectively produced by quenching from 1173 K and cold-rolled deformation followed by isochronal annealing. The PALS results with isochronal annealing showed that the temperature of defects recovery increased in deformed Fe-Cu alloys with Cu content. The increment of Cu content also restrained the migration of vacancies in as-quenched Fe-Cu alloys.

  17. A Preliminary Investigation of the Effect of Bumpers as a Means of Reducing Projectile Penetration

    NASA Technical Reports Server (NTRS)

    Funkhouser, John O.

    1961-01-01

    The results of an investigation to determine the effect of bumpers on projectile penetration indicate that for impact velocities up to 12,500 feet per second, the penetration of 0.062-inch-diameter copper projectiles in to aluminum targets can be definitely reduced by using a properly selected bumper spaced a short distance in front of the main target surface. Bumpers and main targets were made of 2024-T4 aluminum alloy, and spherical projectiles made of 0.062-inch-diameter copper were used in all tests.

  18. Investigation into the effect of plasma pretreatment on the adhesion of parylene to various substrates

    NASA Technical Reports Server (NTRS)

    Riley, T.; Mahuson, T. C.; Seibert, K.

    1980-01-01

    An experimental effort has been undertaken to examine the effect of plasma pretreatment of various substrate materials coated with a polymer in the parylene family. This report describes the procedure and discusses initial data which indicate using plasmas of argon and oxygen to promote adhesion of parylene coatings upon many difficult-to-bond substrates. Substrates investigated were gold, nickel, kovar, teflon (FEP), kapton, silicon, tantalum, titanium, and tungsten. Without plasma treatment, 180 deg peel tests yield a few g/cm (oz/in) strengths. With dc plasma treatment in the deposition chamber, followed by coating, peel strengths are increased by one to two orders of magnitude.

  19. Experimental investigation of a draft tube spouted bed for effects of geometric parameters on operation

    NASA Astrophysics Data System (ADS)

    Azizaddini, Seyednezamaddin; Lin, Weigang; Dam-Johansen, Kim

    2016-06-01

    Experiments are performed in a draft tube spouted bed (DTSB) to investigate effects of the operating conditions and the geometric parameters on the hydrodynamics. Geometry parameters, such as heights of the entrained zone, draft tube inner diameter, inner angle of the conical section were studied. Increasing the draft tube inner diameter, sharper inner angle of the conical section and higher height of entrained zone increase the internal solid circulation rate and the pressure drop. Even though, for all different configurations, higher gas feeding rate leads to higher internal solid circulation rate considering a maximum value.

  20. Flight Investigation of the Effectiveness of an Automatic Aileron Trim Control Device for Personal Airplanes

    NASA Technical Reports Server (NTRS)

    Phillips, William H; Kuehnel, Helmut A; Whitten, James B

    1957-01-01

    A flight investigation to determine the effectiveness of an automatic aileron trim control device installed in a personal airplane to augment the apparent spiral stability has been conducted. The device utilizes a rate-gyro sensing element in order to switch an on-off type of control that operates the ailerons at a fixed rate through control centering springs. An analytical study using phase-plane and analog-computer methods has been carried out to determine a desirable method of operation for the automatic trim control.

  1. Ab Initio Investigations of Thermoelectric Effects in Graphene - Boron Nitride Nanoribbons

    NASA Astrophysics Data System (ADS)

    Visan, Camelia; Nemnes, G. A.

    2016-02-01

    Thermoelectric effects of graphene - hexagonal boron nitride (hBN) nanoribbons have been investigated by density functional theory (DFT) calculations. Pristine zig-zag nanoribbons are not suited to achieve high thermopower as the transmission function is flat around the chemical potential. By introducing hBN inclusions, the nanoribbon systems exhibit enhanced thermopower, due to the asymmetries introduced in the spin dependent transmission functions. Finite temperature differences between the two contacts are considered. The possibility of a good integration of hBN into graphene, makes the hybrid systems suitable for thermoelectric applications, which may be subject to further optimizations.

  2. Investigation of the effects of long duration space exposure on active optical system components

    NASA Technical Reports Server (NTRS)

    Blue, M. D.

    1994-01-01

    This experiment was exposed to the space environment for 6 years on the Long Duration Exposure Facility (LDEF). It investigated quantitatively the effects of the long-duration space exposure on the relevant performance parameters of a representative set of electron-optic system components, including lasers, radiation detectors, filters, modulators, windows, and other related components. It evaluated the results and implications of the measurements indicating real or suspected degradation mechanisms. This information will be used to establish guidelines for the selection and use of components for space-based, electro-optic systems.

  3. Experimental investigation of resonance self-shielding and the Doppler effect in uranium and tantalum

    NASA Technical Reports Server (NTRS)

    Byoun, T. Y.; Block, R. C.; Semler, T. T.

    1972-01-01

    A series of average transmission and average self-indication ratio measurements were performed in order to investigate the temperature dependence of the resonance self-shielding effect in the unresolved resonance region of depleted uranium and tantalum. The measurements were carried out at 77 K, 295 K and approximately 1000 K with sample thicknesses varying from approximately 0.1 to 1.0 mean free path. The average resonance parameters as well as the temperature dependence were determined by using an analytical model which directly integrates over the resonance parameter distribution functions.

  4. Dynamics of spin valves investigated using Magneto-Optical Kerr Effect Spectroscopy

    NASA Astrophysics Data System (ADS)

    Stevens, Christopher; Paul, Jagannath; Dey, Prasenjit; Miller, Casey; McGill, Stephen; Karaiskaj, Denis

    Through an all-optical approach, we are investigating the spin dynamics in different spin torque based structures. Using pump-probe Time-Resolved Magneto-Optical Kerr Effect (TR-MOKE) spectroscopy, we are able to monitor the ultrafast magnon propagation on a sub-picosecond timescale as well as the longer lived oscillations and demagnetization. This represents a recent efforts to realize magnon induced spin torque using an all optical method. This research at USF is supported by the National Science Foundation, Division of Electrical, Communications and Cyber Systems under Grant Number: 1231929. The work was done in part at the NHMFL, Tallahassee, FSU under Grants: DMR-1229217, DMR-1157490.

  5. Experimental investigation of control/display augmentation effects in a compensatory tracking task

    NASA Technical Reports Server (NTRS)

    Garg, Sanjay; Schmidt, David K.

    1988-01-01

    The effects of control/display augmentation on human performance and workload have been investigated for closed-loop, continuous-tracking tasks by a real-time, man-in-the-loop simulation study. The experimental results obtained indicate that only limited improvement in actual tracking performance is obtainable through display augmentation alone; with a very high level of display augmentation, tracking error will actually deteriorate. Tracking performance improves when status information is furnished for reasonable levels of display quickening; again, very high quickening levels lead to tracking error deterioration due to the incompatibility between the status information and the quickened signal.

  6. Empirical investigation of SET seasoning effects in Phase Change Memory arrays

    NASA Astrophysics Data System (ADS)

    Zambelli, C.; Chimenton, A.; Olivo, P.

    2011-04-01

    In this work we have investigated the seasoning effect in SET state occurring during cycling of multimegabit Phase Change Memory arrays. The impact of the erasing waveform on this phenomenon has been experimentally evaluated. The physical nature of the phenomenon has been discussed in relation to the electro-thermal characteristics of the active material. The study of such phenomenon is also important to comprehend the transition dynamics of the GST material towards its crystalline state and to develop accurate models allowing an estimate of the PCM cells behavior as a function of the operative cycles.

  7. The effect of spacers on the performance of Micromegas detectors: A numerical investigation

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Purba; Mukhopadhyay, Supratik; Majumdar, Nayana; Bhattacharya, Sudeb

    2015-09-01

    Micromegas detector is considered to be a promising candidate for a large variety of high-rate experiments. Micromegas of various geometries have already been established as appropriate for these experiments for their performances in terms of gas gain uniformity, energy and space point resolution, and their capability to efficiently pave large read-out surfaces with minimum dead zone. The present work investigates the effect of spacers on different detector characteristics of Micromegas detectors having various amplification gaps and mesh hole pitches. Numerical simulation has been used as a tool of exploration to evaluate the effect of such dielectric material on detector performance. Some of the important and fundamental characteristics such as electron transparency, gain and signal of the Micromegas detector have been estimated.

  8. Experimental Investigation on Strengthening Effect of Cu2O Film in Micro Sheet Forming of Copper

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Lin, Xiaojuan; Tang, Bingtao; Wang, Guangchun

    2016-05-01

    Materials processed using micro-manufacturing technologies exhibit significantly different properties compared to those produced using conventional macro-manufacturing techniques. In this paper, the uniaxial tensile tests were performed on the thin sheet specimens of pure copper to investigate how the sheet thickness impacts the flow stress. The experimental results show a continuous decrease of flow stress as the sheet thickness reduces from 200 to 100 μm, but an increase of flow stress with further reduction in thickness. Firstly, by introducing the ratio of surface grains, the decrease trend of flow stress was explained on the basis of surface layer model. Secondly, the strengthening effect of Cu2O film was clearly demonstrated by the x-ray diffraction and electrodeposition process. Finally, considering the effects of Cu2O film and free surface layer, the mechanical properties of Cu2O film was studied, which is helpful to explain the material behavior in micro sheet forming.

  9. Computer Technology Training in the Workplace: A Longitudinal Investigation of the Effect of Mood.

    PubMed

    Venkatesh; Speier

    1999-07-01

    How does a person's mood during technology training influence motivation, intentions, and, ultimately, usage of the new technology? Do these mood effects dissipate or are they sustainable over time? A repeated-measures field study (n = 316) investigated the effect of mood on employee motivation and intentions toward using a specific computer technology at two points in time: immediately after training and 6 weeks after training. Actual usage behavior was assessed for 12 weeks after training. Each individual was assigned to one of three mood treatments: positive, negative, or control. Results indicated that there were only short-term boosts in intrinsic motivation and intention to use the technology among individuals in the positive mood intervention. However, a long-term lowering of intrinsic motivation and intention was observed among those in the negative mood condition. Copyright 1999 Academic Press. PMID:10388607

  10. AN EXPLORATORY STUDY INVESTIGATING THE EFFECTS OF A TREATMENT MANUAL FOR VIDEO GAME ADDICTION.

    PubMed

    Pallesen, Ståle; Lorvik, Ingjerd Meen; Bu, Eli Hellandsjø; Molde, Helge

    2015-10-01

    This study investigated the effects of a manualized therapy for video game addiction in 12 males, ages 14-18 yr. The manual was based on cognitive-behavioral therapy, short-term strategic family therapy, solution-focused therapy, and motivational interviewing. Treatment response was reported by the patients, their mothers, and the therapists. The patients reported moderate (but statistically non-significant) improvement from pre- to post-treatment. The mothers, however, reported large effects and statistically significant improvement from pre- to post-treatment. The therapists reported marked or moderate treatment response in six of the 12 patients. The ratings of change by mothers converged well with the views of change of both the patients and therapists, whereas the convergence of views on change between the two latter sources was far lower. PMID:26340051

  11. Investigation of flaw geometry and loading effects on plane strain fracture in metallic structures

    NASA Technical Reports Server (NTRS)

    Hall, L. R.; Finger, R. W.

    1971-01-01

    The effects on fracture and flaw growth of weld-induced residual stresses, combined bending and tension stresses, and stress fields adjacent to circular holes in 2219-T87 aluminum and 5AI-2.5Sn(ELI) titanium alloys were evaluated. Static fracture tests were conducted in liquid nitrogen; fatigue tests were performed in room air, liquid nitrogen, and liquid hydrogen. Evaluation of results was based on linear elastic fracture mechanics concepts and was directed to improving existing methods of estimating minimum fracture strength and fatigue lives for pressurized structure in spacecraft and booster systems. Effects of specimen design in plane-strain fracture toughness testing were investigated. Four different specimen types were tested in room air, liquid nitrogen and liquid hydrogen environments using the aluminum and titanium alloys. Interferometry and holograph were used to measure crack-opening displacements in surface-flawed plexiglass test specimens. Comparisons were made between stress intensities calculated using displacement measurements, and approximate analytical solutions.

  12. Ultrastructural investigations on protective effects of NCX 4016 (nitroaspirin) on macrovascular endothelium in diabetic Wistar rats.

    PubMed

    Ambrosini, M V; Mariucci, G; Rambotti, M G; Tantucci, M; Covarelli, C; De Angelis, L; Del Soldato, P

    2005-08-01

    The effect of a nitric oxide-donating aspirin derivative, 2-acetoxy-benzoate 3-(nitroxy-methyl)phenyl ester (NCX 4016), and aspirin on the aortic endothelium of diabetic rats was investigated by using scanning and transmission electron microscopy. Control and streptozotocin-treated rats were used. Metabolic control was assessed by measuring blood and urine metabolites, and 24-h urine volume. The ultrastructural study was performed after 7 weeks of diabetes and 6 weeks of therapy. Streptozotocin treatment induced a persistent hyperglycemia which was not influenced by the pharmacological treatments. Values of blood metabolites were in line with the diabetic status. Both scanning and transmission electron microscopy revealed that aortic endothelium was severely damaged in all diabetic rats except for the NCX 4016 treated ones. Our data document the protective effects of NCX 4016 on the vascular endothelium of diabetic rats. Since aspirin had no protective action, NCX 4016 may have exerted its beneficial action by releasing nitric oxide. PMID:16335593

  13. Investigation of arterial gas occlusions. [effect of noncondensable gases on high performance heat pipes

    NASA Technical Reports Server (NTRS)

    Saaski, E. W.

    1974-01-01

    The effect of noncondensable gases on high-performance arterial heat pipes was investigated both analytically and experimentally. Models have been generated which characterize the dissolution of gases in condensate, and the diffusional loss of dissolved gases from condensate in arterial flow. These processes, and others, were used to postulate stability criteria for arterial heat pipes under isothermal and non-isothermal condensate flow conditions. A rigorous second-order gas-loaded heat pipe model, incorporating axial conduction and one-dimensional vapor transport, was produced and used for thermal and gas studies. A Freon-22 (CHCIF2) heat pipe was used with helium and xenon to validate modeling. With helium, experimental data compared well with theory. Unusual gas-control effects with xenon were attributed to high solubility.

  14. Experimental investigation of the temperature effects on CO2 permeability of fractured coal rock

    NASA Astrophysics Data System (ADS)

    Ju, Yang; Wang, Huijie; Pathegama Gamage, Ranjith; Sun, Huafei

    2012-11-01

    Accurate prediction of gas permeability is of great significance for coalbed methane production and CO2 sequestration. The permeability of coal rock plays a key role in determining coalbed methane productivity in the application of simultaneous excavation of coal and gas in deep coal mines. The main objective of this study is to investigate the temperature effects on the permeability of fractured coal rock in deep coal seams. The CO2 permeability of the fractured coal samples obtained from Ping Ding Shan coalfield, China, was measured using high pressure undrained triaxial apparatus. To probe the temperature effects, four levels of temperatures (25-75^o) were tested with the injection pressures ranging from 7 to 11MPa and a confining pressure of 15MPa. It is shown that the CO2 permeability of the fractured coal rock rises apparently with an increasing temperature. The physical mechanism that governs the CO2 permeability of coal rock is discussed in this study.

  15. [Effect of technological parameters of sputtering on the microstructure of silicon film investigated by Raman analysis].

    PubMed

    Tian, Gui; Zhu, Jia-qi; Han, Jie-cai; Jiang, Chun-zhu; Jia, Ze-chun

    2010-07-01

    In order to facilitate optical polishing of silicon carbide space telescope, in the present paper, silicon film, which has similar coefficient of thermal expansion with silicon carbide, was fabricated on SiC substrate by radio frequency magnetron sputtering. The effect of substrate temperature, radio frequency power, and substrate bias voltage was investigated by Raman scattering. The results indicate that at lower substrate temperature, the crystalline volume fraction of Si films increases with the increase in deposition temperature. Exceeding a certain temperature, the crystalline volume fraction decreases with further increasing deposition temperature; the increase in substrate bias voltage is bad for forming crystalline structure; the effect of radio power on microstructure of silicon film is comparatively complicated. As the rf power increases, the cluster size and crystallite volume fraction decrease, and both of them increase with further increasing the rf power. But when the rf power is too high, the crystallite volume fraction of the silicon film will decrease slightly. PMID:20827972

  16. Investigation of Trends in Aerosol Direct Radiative Effects over North America Using a Coupled Meteorology-Chemistry Model

    EPA Science Inventory

    A comprehensive investigation of the processes regulating tropospheric aerosol distributions, their optical properties, and their radiative effects in conjunction with verification of their simulated radiative effects for past conditions relative to measurements is needed in orde...

  17. Investigations of Ar ion irradiation effects on nanocrystalline SiC thin films

    NASA Astrophysics Data System (ADS)

    Craciun, V.; Craciun, D.; Socol, G.; Behdad, S.; Boesl, B.; Himcinschi, C.; Makino, H.; Socol, M.; Simeone, D.

    2016-06-01

    The effects of 800 keV Ar ion irradiation on thin nanocrystalline SiC films grown on (100) Si substrates using the pulsed laser deposition (PLD) technique were investigated. On such PLD grown films, which were very dense, flat and smooth, X-ray reflectivity, glancing incidence X-ray diffraction and nanoindentation investigations were easily performed to evaluate changes induced by irradiation on the density, surface roughness, crystalline structure, and mechanical properties. Results indicated that the SiC films retained their crystalline nature, the cubic phase partially transforming into the hexagonal phase, which had a slightly higher lattice parameter then the as-deposited films. Simulations of X-ray reflectivity curves indicated a 3% decrease of the films density after irradiation. Nanoindentation results showed a significant decrease of the hardness and Young's modulus values with respect to those measured on as-deposited films. Raman and X-ray photoelectron spectroscopy investigations found an increase of the Csbnd C bonds and a corresponding decrease of the Sisbnd C bonds in the irradiated area, which could explain the degradation of mechanical properties.

  18. An Experimental Investigation of the Effects of Charging on the International Space Station

    NASA Technical Reports Server (NTRS)

    Schneider, Todd; Carruth, M. Ralph; Finckenor, Miria; Vaughn, Jason; Ferguson, Dale; Heard, John

    2001-01-01

    An experimental investigation has been undertaken to determine the effects associated with operating the International Space Station (ISS) without a Plasma Contactor Unit (PCU). The role of the PCU is to maintain the potential of the ISS to within 40 volts of the ambient plasma potential. In the event of a PCU failure, ISS structure may charge to - 160 volts with respect to the Low Earth Orbit (LEO) plasma, due to the use of high voltage photovoltaic solar arrays. Operation without a PCU will result in the charging of the oxide layers on anodized aluminum components facing into the RAM direction. In this investigation, arcs were observed as a result of anodized materials charging in a plasma environment. Actual ISS materials were used in the investigation. The materials included meteoroid and debris shield samples, as well as components from the Extravehicular Mobility Unit (EMU). Results show that the occurrence of arcs was dependent on several factors including material composition and applied voltage. The breakdown thresholds for the materials tested will be shown, as well as the voltage and current waveforms during an arc event. The damage resulting from an arc will also be described. In addition, a description of associated operational hazards resulting from arcing on the spacecraft will be provided.

  19. Investigation into the Effects of Microsecond Power Line Transients on Line-Connected Capacitors

    NASA Technical Reports Server (NTRS)

    Javor, K.

    2000-01-01

    An investigation was conducted into the effect of power-line transients on capacitors used by NASA and installed on platform primary power inputs to avionics. The purpose was to investigate whether capacitor voltage ratings needs to be derated for expected spike potentials. Concerns had been voiced in the past by NASA suppliers that MIL-STD-461 CS06-like requirements were overly harsh and led to physically large capacitors. The author had previously predicted that electrical-switching spike requirements representative of actual power-line transient potentials, durations. and source impedance would require no derating. This investigation bore out that prediction. It was further determined that traditional low source impedance CS06-like transients also will not damage a capacitor, although the spikes themselves are not nearly as well filtered. This report should be used to allay fears that CS06-like requirements drive capacitor voltage derating. Only that derating required by the relatively long duration transients in power quality specification need concern the equipment designer.

  20. Investigation Into The Effects of Microsecond Power Line Transients On Line-Connected Capacitors

    NASA Technical Reports Server (NTRS)

    Javor, Ken

    1999-01-01

    An investigation was conducted into the effect of power-line transients on capacitors used by NASA and installed on platform primary power inputs to avionics. The purpose was to investigate whether capacitor voltage rating needs to be derated for expected spike potentials. Concerns had been voiced in the past by NASA suppliers that MIL-STD-461 CS06-like requirements were overly harsh and led to physically large capacitors. The author had previously predicted that electrical-switching spike requirements representative of actual power-line transient potentials, durations and source impedance would require no derating. This investigation bore out that prediction. It was further determined that traditional low source impedance CS06-like transients also will not damage a capacitor, although the spikes themselves are not nearly as well filtered. This report should be used to allay fears that CS06-like requirements drive capacitor voltage derating. Only that derating required by the relatively long duration transients in power quality specification need concern the equipment designer.

  1. Effects of an Online Alcohol Education Course Among College Freshmen: An Investigation of Potential Mediators

    PubMed Central

    Ringwalt, Chris; Wyatt, Todd; DeJong, William

    2014-01-01

    This study investigated possible mediating effects of psychosocial variables (perceived drinking norms, positive and negative alcohol expectancies, personal approval of alcohol use, protective behavioral strategies) targeted by an online alcohol education course (AlcoholEdu for College) as part of a 30-campus randomized trial with 2,400 first-year students. Previous multi-level analyses found significant effects of the AlcoholEdu course on the frequency of past-30-day alcohol use and binge drinking during the fall semester, and the most common types of alcohol related problems. Exposure to the online AlcoholEdu course was inversely related to perceived drinking norms, but was not related to any of the other psychosocial variables. Multi-level analyses indicated at least partial mediating effects of perceived drinking norms on the behavioral outcomes. Findings of this study suggest that AlcoholEdu for College affects alcohol use and related consequences indirectly through its effect on student perceptions of drinking norms. Further research is needed to better understand why this online course did not appear to affect other targeted psychosocial variables. PMID:24156616

  2. Effects of an online alcohol education course among college freshmen: an investigation of potential mediators.

    PubMed

    Paschall, Mallie J; Ringwalt, Chris; Wyatt, Todd; Dejong, William

    2014-04-01

    The authors investigated possible mediating effects of psychosocial variables (perceived drinking norms, positive and negative alcohol expectancies, personal approval of alcohol use, protective behavioral strategies) targeted by an online alcohol education course (AlcoholEdu for College) as part of a 30-campus randomized trial with 2,400 first-year students. Previous multilevel analyses have found significant effects of the AlcoholEdu course on the frequency of past-30-day alcohol use and binge drinking during the fall semester, and the most common types of alcohol-related problems. Exposure to the online AlcoholEdu course was inversely related to perceived drinking norms but was not related to any of the other psychosocial variables. Multilevel analyses indicated at least partial mediating effects of perceived drinking norms on behavioral outcomes. Findings of this study suggest that AlcoholEdu for College affects alcohol use and related consequences indirectly through its effect on student perceptions of drinking norms. Further research is needed to better understand why this online course did not appear to affect other targeted psychosocial variables. PMID:24156616

  3. A Investigation of a Possible Molecular Effect in Ion Atom Collision Using a Gaseous Argon Target

    NASA Astrophysics Data System (ADS)

    Arora, Sanjeev

    1992-01-01

    The present work deals with an investigation of the molecular effect, which is defined as the difference in experimental results using isotachic atomic ion and molecular ion beams in ion atom collisions. Previous studies have dealt almost exclusively with total cross section measurements. This thesis explores the idea that the molecular effect may be more pronounced in the differential ionization probability of the target atoms. Also, a gaseous argon target of sufficiently low density was used in order to ensure that the two correlated protons in the H _2^{+} beam did not interact with two adjacent target atoms simultaneously. We report that, contrary to the expectations noted above, the molecular effect in the K shell differential ionization probability of argon for scattering angles up to 90^circ appears to be no more than the molecular effect in the total ionization probability. The uncertainity in our results is statistical in nature and can be improved upon by running the experiment for a longer duration of time.

  4. A numerical investigation on the ground effect of a flapping-flying bird

    NASA Astrophysics Data System (ADS)

    Su, Jian-Yuan; Tang, Jhen-Han; Wang, Ching-Hua; Yang, Jing-Tang

    2013-09-01

    The flight of a small bird under the influence of the ground effect is numerically investigated with a complete three-dimensional model including the bird's body and wings. The flight mode is not the conventional steady gliding flight but an unsteady flight consisting of flapping, twisting, and folding motions. As the bird approaches the ground, the average lift force gradually increases while the average drag force decreases. At a particular distance, the average lift force increases by approximately 47%, whereas the average drag force decreases by nearly 20%, relative to the absence of the ground effect. Because of the ground, the improved aerodynamic performance in flapping flight is much more significant than in steady flight, in which the modification of the lift-drag ratio is typically less than 10%. On the basis of the flow field, regardless of the presence or absence of the ground, there exists no evidence for an obstruction of a wing-tip vortex, which is a remarkable phenomenon and accounts for the improved performance in steady flight. The extent of the region of high pressure beneath the wing in the near-ground case seems to surpass that in the far-ground case, accounting for the greater lift and thrust forces in the near-ground case. This air cushion beneath the wing, known as the cram effect, is the dominant factor of the ground effect on a flapping bird.

  5. Should Cost-Effectiveness Analysis Include the Cost of Consumption Activities? AN Empirical Investigation.

    PubMed

    Adarkwah, Charles Christian; Sadoghi, Amirhossein; Gandjour, Afschin

    2016-02-01

    There has been a debate on whether cost-effectiveness analysis should consider the cost of consumption and leisure time activities when using the quality-adjusted life year as a measure of health outcome under a societal perspective. The purpose of this study was to investigate whether the effects of ill health on consumptive activities are spontaneously considered in a health state valuation exercise and how much this matters. The survey enrolled patients with inflammatory bowel disease in Germany (n = 104). Patients were randomized to explicit and no explicit instruction for the consideration of consumption and leisure effects in a time trade-off (TTO) exercise. Explicit instruction to consider non-health-related utility in TTO exercises did not influence TTO scores. However, spontaneous consideration of non-health-related utility in patients without explicit instruction (60% of respondents) led to significantly lower TTO scores. Results suggest an inclusion of consumption costs in the numerator of the cost-effectiveness ratio, at least for those respondents who spontaneously consider non-health-related utility from treatment. Results also suggest that exercises eliciting health valuations from the general public may include a description of the impact of disease on consumptive activities. PMID:25684073

  6. Experimental and numerical investigations of the phase-shift effect in capacitively coupled discharges

    SciTech Connect

    Gao, Fei; Zhang, Yu-Ru; Zhao, Shu-Xia; Wang, You-Nian

    2014-08-15

    The phase-shift effect has been investigated by a Langmuir probe and a fluid model in Ar capacitively coupled plasmas at 50 mTorr. In the discharge, two sources with the same frequency, i.e., 27.12 MHz, are applied on the top and bottom electrodes simultaneously, and the phase shift between them varies from 0 to π. It is found that the electron density has an off-axis peak near the radial edge when the phase difference is equal to 0 due to the electrostatic edge effect, and the best radial uniformity is observed at a phase difference equal to π. Furthermore, when the voltage increases, the best radial uniformity is obtained at lower phase shift values. Moreover, the electron energy probability function has a bi-temperature structure at all the selected phase differences at r = 1–15 cm. The evolution of the plasma characteristics with the phase difference implies that the best radial uniformity can be obtained, by balancing the electrostatic edge effect and the phase shift effect.

  7. Investigation of the effects of sleeper-passing impacts on the high-speed train

    NASA Astrophysics Data System (ADS)

    Wu, Xingwen; Cai, Wubin; Chi, Maoru; Wei, Lai; Shi, Huailong; Zhu, Minhao

    2015-12-01

    The sleeper-passing impact has always been considered negligible in normal conditions, while the experimental data obtained from a High-speed train in a cold weather expressed significant sleeper-passing impacts on the axle box, bogie frame and car body. Therefore, in this study, a vertical coupled vehicle/track dynamic model was developed to investigate the sleeper-passing impacts and its effects on the dynamic performance of the high-speed train. In the model, the dynamic model of vehicle is established with 10 degrees of freedom. The track model is formulated with two rails supported on the discrete supports through the finite element method. The contact forces between the wheel and rail are estimated using the non-linear Hertz contact theory. The parametric studies are conducted to analyse effects of both the vehicle speeds and the discrete support stiffness on the sleeper-passing impacts. The results show that the sleeper-passing impacts become extremely significant with the increased support stiffness of track, especially when the frequencies of sleeper-passing impacts approach to the resonance frequencies of wheel/track system. The damping of primary suspension can effectively lower the magnitude of impacts in the resonance speed ranges, but has little effect on other speed ranges. Finally, a more comprehensively coupled vehicle/track dynamic model integrating with a flexible wheel set is developed to discuss the sleeper-passing-induced flexible vibration of wheel set.

  8. Antineoplastic effect of calycosin on osteosarcoma through inducing apoptosis showing in vitro and in vivo investigations.

    PubMed

    Qiu, Rubiao; Ma, Gang; Zheng, Chenguang; Qiu, Xiaoxia; Li, Xinning; Li, Xueyu; Mo, Jianlan; Li, Zhengzhao; Liu, Yun; Mo, Linjian; Bi, Guan; Ye, Yu

    2014-08-01

    Recently, increasing studies have documented that tumorigenesis closely relates to apoptotic processes. Thus, inducing apoptosis is an anti-cancer strategy against osteosarcoma. Here we investigated the anti-proliferative effect of calycosin on human osteosarcoma cell (143B) in vitro. The results showed that calycosin dose-dependently inhibited 143B cell proliferation as reflected in tetrazolium salt (MTT) assay (P<0.01). In addition, calycosin effectively down-regulated cellular mRNA expressions of IκBα, NF-κB p65 and cyclin D1 through RT-PCR assay (P<0.01). Next, calycosin-mediated inhibitory effect on 143B tumor-bearing nude mice and the underlying mechanism were evaluated and discussed. As a result, calycosin administration significantly blocked solid tumor growth in 143B-harbored nude mice (P<0.01). Furthermore, intracellular Bcl-2 protein expression was effectively reduced in 143B-harbored tumor tissue through western blotting analysis (P<0.01), while intratumoral Apaf-1 and cleaved Caspase-3 protein levels were up-regulated, respectively (P<0.01). Taken together, calycosin possesses the anti-osteosarcoma potential, in which the mechanism involved was associated with activation of apoptotic, thus inducing apoptosis. PMID:24797937

  9. An empirical investigation of the efficiency effects of integrated care models in Switzerland

    PubMed Central

    Reich, Oliver; Rapold, Roland; Flatscher-Thöni, Magdalena

    2012-01-01

    Introduction This study investigates the efficiency gains of integrated care models in Switzerland, since these models are regarded as cost containment options in national social health insurance. These plans generate much lower average health care expenditure than the basic insurance plan. The question is, however, to what extent these total savings are due to the effects of selection and efficiency. Methods The empirical analysis is based on data from 399,274 Swiss residents that constantly had compulsory health insurance with the Helsana Group, the largest health insurer in Switzerland, covering the years 2006–2009. In order to evaluate the efficiency of the different integrated care models, we apply an econometric approach with a mixed-effects model. Results Our estimations indicate that the efficiency effects of integrated care models on health care expenditure are significant. However, the different insurance plans vary, revealing the following efficiency gains per model: contracted capitated model 21.2%, contracted non-capitated model 15.5% and telemedicine model 3.7%. The remaining 8.5%, 5.6% and 22.5%, respectively, of the variation in total health care expenditure can be attributed to the effects of selection. Conclusions Integrated care models have the potential to improve care for patients with chronic diseases and concurrently have a positive impact on health care expenditure. We suggest policy-makers improve the incentives for patients with chronic diseases within the existing regulations providing further potential for cost-efficiency of medical care. PMID:22371691

  10. Investigation of wind and rain effects in a foliated tropical region for fixed wireless access

    NASA Astrophysics Data System (ADS)

    Muhammad, N. A.; Rahman, T. A.; Rahim, S. K. A.; Kesavan, U.; Assis, M. S.

    2014-09-01

    This paper investigates the effects of trees on fixed wireless access operating at 5.8 GHz frequency of the Unlicensed National Information Infrastructure (UNII) band. Measurements are focused on the temporal scale of the received signal strength for a three different links (one line of sight (LOS) link and two non-line of sight (NLOS) link). The statistical characterisation of the combined effects of typical weather phenomena often experienced in a tropical region is presented. As expected, the LOS link is not affected even during heavy rain condition. However, the presence of trees in the vicinity of the transmission path can cause relevant signal deterioration in the case of NLOS link, where the fading of the received signal varies from 2 to 16 dB as the strength of wind and rain increases. Rician distribution can be used to characterise the temporal variation of these weather effects. The work reported in this paper enables the effects of wind, rain and humidity to be properly taken into consideration in the deployment of fixed wireless links in a foliated channel, allowing an optimisation of planning for the end users.

  11. Analytical investigation of the effects of lateral connections on the accuracy of population coding

    NASA Astrophysics Data System (ADS)

    Oizumi, Masafumi; Miura, Keiji; Okada, Masato

    2010-05-01

    We studied how lateral connections affect the accuracy of a population code by using a model of orientation selectivity in the primary visual cortex. Investigating the effects of lateral connections on population coding is a complex problem because these connections simultaneously change the shape of tuning curves and correlations between neurons. Both of these changes caused by lateral connections have to be taken into consideration to correctly evaluate their effects. We propose a theoretical framework for analytically computing the Fisher information, which measures the accuracy of a population code, in stochastic spiking neuron models with refractory periods. Within our framework, we accurately evaluated both the changes in tuning curves and correlations caused by lateral connections and their effects on the Fisher information. We found that their effects conflicted with each other and the answer to whether or not the lateral connections increased the Fisher information strongly depended on the intrinsic properties of the model neuron. By systematically changing the coupling strengths of excitations and inhibitions, we found the parameter regions of lateral connectivities where sharpening of tuning curves through Mexican-hat connectivities led to an increase in information, which is in contrast to some previous findings.

  12. A preliminary investigation into the neural basis of the production effect.

    PubMed

    Hassall, Cameron D; Quinlan, Chelsea K; Turk, David J; Taylor, Tracy L; Krigolson, Olave E

    2016-06-01

    Items that are produced (e.g., read aloud) during encoding typically are better remembered than items that are not produced (e.g., read silently). This "production effect" has been explained by distinctiveness: Produced items have more distinct features than nonproduced items, leading to enhanced retrieval. The goal of the current study was to use electroencephalography (EEG) to examine the neural basis of the production effect. During study, participants were presented with words that they were required to read silently, read aloud, or sing while EEG data were recorded. Subsequent memory performance was tested using a yes/no recognition test. Analysis focused on the event-related brain potentials (ERPs) evoked by the encoding instruction cue for each instruction condition. Our data revealed enhanced memory performance for produced items and a greater P300 ERP amplitude for instructions to sing or read aloud compared with instructions to read silently. Our results demonstrate that the amplitude of the P300 is modulated by at least 1 aspect of production, vocalization (singing/reading aloud relative to reading silently), and are consistent with the distinctiveness account of the production effect. The ERP methodology is a viable tool for investigating the production effect. (PsycINFO Database Record PMID:27244355

  13. An Investigation of the Effects of Reader Characteristics on Reading Comprehension Of a General Chemistry Text

    NASA Astrophysics Data System (ADS)

    Neiles, Kelly Y.

    There is great concern in the scientific community that students in the United States, when compared with other countries, are falling behind in their scientific achievement. Increasing students' reading comprehension of scientific text may be one of the components involved in students' science achievement. To investigate students' reading comprehension this quantitative study examined the effects of different reader characteristics, namely, students' logical reasoning ability, factual chemistry knowledge, working memory capacity, and schema of the chemistry concepts, on reading comprehension of a chemistry text. Students' reading comprehension was measured through their ability to encode the text, access the meanings of words (lexical access), make bridging and elaborative inferences, and integrate the text with their existing schemas to make a lasting mental representation of the text (situational model). Students completed a series of tasks that measured the reader characteristic and reading comprehension variables. Some of the variables were measured using new technologies and software to investigate different cognitive processes. These technologies and software included eye tracking to investigate students' lexical accessing and a Pathfinder program to investigate students' schema of the chemistry concepts. The results from this study were analyzed using canonical correlation and regression analysis. The canonical correlation analysis allows for the ten variables described previously to be included in one multivariate analysis. Results indicate that the relationship between the reader characteristic variables and the reading comprehension variables is significant. The resulting canonical function accounts for a greater amount of variance in students' responses then any individual variable. Regression analysis was used to further investigate which reader characteristic variables accounted for the differences in students' responses for each reading comprehension

  14. Effects of Spatially Heterogeneous Porosity on Matrix-Diffusion as Investigated by X ray Absorption Imaging

    SciTech Connect

    Boney, C.; Christian-Frear, T.; Meigs, L.C.; Tidwell, V.C.

    1998-10-20

    Laboratory experiments were performed to investigate the effects of spatial variation in porosity on matrix-diffusion processes. Four centimeter-scale slabs of Culebra dolomite taken from the Waste Isolation Pilot Plant site were used in the tests. Experiments involved the simple diffusion of iodine into a single edge of each rock slab while X ray absorption imaging was used to measure the resulting two-dmensional solute concentration field as a function of time. X ray imaging was also used to quantify the two-dimensional porosity field of each rock slab. Image analysis provided a unique opportunity to both visuake and quantifj the effects of the spatially variable porosi~ on matrixdMusion. Four key results were obtained. First, significant variation in rates of diffusion were realized over the relatively small length (centimeter) and time scales (months) investigated. Second, clear evidence of diffusion preferentially following zones of relatively higher porosity was noted. Third, rate of difhion was found to vary as tracer diffused into the rock slabs encountering changing porosity conditions. Fourth, strong correlation between porosi~ and the calculated diffusion coefficients was found. In fact, the nature of the correlation can be related to the geometry, position, and orientation of the heterogeneous porosity features populating each rock slab.

  15. Investigation of the phototoxic effect of ZnO nanorods on fibroblasts and melanoma human cells

    NASA Astrophysics Data System (ADS)

    Kishwar, S.; Siddique, M.; Israr-Qadir, M.; Nur, O.; Willander, M.; Öllinger, K.

    2014-11-01

    Photocytotoxic effects of as-grown and zinc oxide (ZnO) nanorods coated with 5-aminolevulinic acid (ALA) have been studied on human cells, i.e. melanoma and foreskin fibroblast, under dark and ultraviolet light exposures. Zinc oxide nanorods have been grown on the very sharp tip (diameter = 700 nm) of borosilicate glass pipettes and then were coated by the photosensitizer for targeted investigations inside human cells. The coated glass pipette’s tip with photosensitizer has been inserted inside the cells with the help of a micro-manipulator and irradiated through ultraviolet light (UVA), which reduces the membrane potential of the mitochondria leading to cell death. Cell viability loss has been detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay when exposed to the dissolved ZnO nanorods and the production of the reactive oxygen species (ROS) has been detected along with the enhanced cytotoxic effect under UVA irradiation. Additionally, the influence of the lipid soluble antioxidant vitamin E and water-soluble N-acetyl-cysteine toward the enhancement or reduction of the toxicity has been investigated. A comparative analysis of the toxic nature of ZnO nanorods has been drawn between normal human fibroblast and melanoma cells, which can be favorable for understanding the clinical setting for killing tumor cells.

  16. Effect of Calcifications on Breast Ultrasound Shear Wave Elastography: An Investigational Study

    PubMed Central

    Gregory, Adriana; Mehrmohammadi, Mohammad; Denis, Max; Bayat, Mahdi; Stan, Daniela L.; Fatemi, Mostafa; Alizad, Azra

    2015-01-01

    Purpose To investigate the effects of macrocalcifications and clustered microcalcifications associated with benign breast masses on shear wave elastography (SWE). Methods SuperSonic Imagine (SSI) and comb-push ultrasound shear elastography (CUSE) were performed on three sets of phantoms to investigate how calcifications of different sizes and distributions influence measured elasticity. To demonstrate the effect in vivo, three female patients with benign breast masses associated with mammographically-identified calcifications were evaluated by CUSE. Results Apparent maximum elasticity (Emax) estimates resulting from individual macrocalcifications (with diameters of 2mm, 3mm, 5mm, 6mm, 9mm, 11mm, and 15mm) showed values over 50 kPa for all cases, which represents more than 100% increase over background (~21kPa). We considered a 2cm-diameter circular region of interest for all phantom experiments. Mean elasticity (Emean) values varied from 26 kPa to 73 kPa, depending on the macrocalcification size. Highly dense clusters of microcalcifications showed higher Emax values than clusters of microcalcification with low concentrations, but the difference in Emean values was not significant. Conclusions Our results demonstrate that the presence of large isolated macrocalcifications and highly concentrated clusters of microcalcifications can introduce areas with apparent high elasticity in SWE. Considering that benign breast masses normally have significantly lower elasticity values than malignant tumors, such areas with high elasticity appearing due to presence of calcification in benign breast masses may lead to misdiagnosis. PMID:26368939

  17. Theoretical investigation of ionic effects in actuation and sensing of IPMCs of various geometries

    NASA Astrophysics Data System (ADS)

    Stalbaum, Tyler; Nelson, Shelby E.; Palmre, Viljar; Kim, Kwang J.

    2015-04-01

    Ionic polymer-metal composite (IPMC) electromechanical and mechanoelectrical phenomena for rectangular and tube-shaped IPMC devices have been examined through simulation and experimental investigation. There is a specific focus on investigating the anion and cation effects in actuation versus sensing. Simulations were performed using COMSOL Multiphysics 4.3b. Sample IPMCs were fabricated in lab in the desired geometries by techniques described herein. The sample sizes were roughly 1 mm thick and 20-25 mm in length. Actuation and sensor experiments were performed with the samples and compared to simulation results, which exhibit good agreement for voltage and tip displacement measurements. Fundamental differences in the electromechanical and mechanoelectrical transductions of IPMCs are highlighted in the simulation results. These results display the negligible effect of anion motion in actuation as compared to during sensing. In actuation, the cation motion is dominated by an electric potential flux, and the anions move only slightly in accordance with the deformed polymer membrane. In sensing, the electric potential is induced by the ionic migration in the polymer, and both cation and anion concentration variations are of similar magnitudes.

  18. Investigation of degradation effects in polymer electrolyte fuel cells under automotive-related operating conditions

    NASA Astrophysics Data System (ADS)

    Enz, S.; Dao, T. A.; Messerschmidt, M.; Scholta, J.

    2015-01-01

    The influence of artificial starvation effects during automotive-related operating conditions is investigated within a polymer electrolyte fuel cell (PEFC) using non-dispersive infrared sensors and a current scan shunt. Driving cycles (DC) and single load change experiments are performed with specific fuel and oxidant starvation conditions. Within the DC experiments, a maximal CO2 amount of 4.67 μmol per cycle is detected in the cathode and 0.97 μmol per cycle in the anode exhaust without reaching fuel starvation conditions during the DC. Massive cell reversal conditions occur within the single load change experiments as a result of anodic fuel starvation. As soon as a fuel starvation appears, the emitted CO2 increases exponentially in the anode and cathode exhaust. A maximal CO2 amount of 143.8 μmol CO2 on the anode side and 5.8 μmol CO2 on the cathode side is detected in the exhaust gases. The critical cell reversal conditions only occur by using hydrogen reformate as anode reactant. The influence of the starvation effects on the PEFC performance is investigated via polarization curves, cyclic and linear sweep voltammetry as well as electrochemical impedance spectroscopy. The PEFC performance is reduced by 47% as a consequence of the dynamic operation.

  19. Investigation of the Effect of Electrical Current Variance on Thermoelectric Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Gomez, Miguel; Ohara, Brandon; Reid, Rachel; Lee, Hohyun

    2014-06-01

    The performance of thermoelectric modules for energy-harvesting applications is investigated, and a model is presented to predict module performance. Derived from energy conservation equations, the model predicts module performance by solving for the temperatures at both ends of the thermoelectric materials within a module. Unlike traditional methods, the model accounts for the effect of electrical current with respect to the load resistance by considering additional heat transfer by Joule heating and the Peltier effect. This establishes a nonlinear quadratic form of temperatures which can be solved by an iterative numerical solution. The model is extended to predict the performance of energy-harvesting systems, which may include connection of multiple thermoelectric modules in series to meet the necessary power requirements. However, a key issue with multiple module connection is the power reduction that arises when there are significant differences in module properties and/or the corresponding external conditions to which each individual module is exposed. Power reduction is thus investigated, as in some cases the overall power output for multiple modules can be less than the power output of a single module. For validation and comparison of the model, experimental support is provided for the case of two commercial thermoelectric modules connected in series. The model also provides optimum load resistances, and a system optimization of the number of modules for a designated heat sink to maximize power generation. The overarching goal of this work is to provide performance prediction and optimization considerations for actual thermoelectric energy-harvesting systems.

  20. Experimental investigations and numerical simulations of notch effect in cellular plastic materials

    NASA Astrophysics Data System (ADS)

    Marsavina, L.; Linul, E.; Voiconi, T.; Negru, R.

    2016-04-01

    Cellular plastics are light weight structures with many applications in civil, aeronautical, automotive and mechanical engineering. Properties of cellular materials depend on the properties of the solid material, on the shape and dimensions of the cellular structure and on the relative density of the cellular material. Most of cellular plastic materials are crushing in compression and have a brittle behavior in tension. The effect of notches represents an important issue in such materials, taking into account that for packing applications for example, notches/holes should be introduced in the cellular material. This paper investigates the effect of notches in compression for three different densities 100, 145 and 300 kg/m3 polyurethane (PUR) foams. Experimental investigations were performed on rectangular blocks of 100×100×25 mm with 16, 28 and 40 mm central holes. The mechanism of damage was monitored with an IR camera FLIR A40M. Purpose of the numerical simulations was to calibrate a material model, based on compression test for un-notched specimens using the CRUSHABLE FOAM models implemented in ABAQUS SIMULIA. Then the material models were used to simulate the experimental tests on notched blocks. Good agreement was obtained for the load - displacement curves obtained experimentally and from simulation. Also the plastic deformation patterns observed experimentally by IR thermograpghy were obtained numerically using the CRUSHABLE FOAM material model.

  1. Flight Investigation of the Effects of Pressure-Belt Tubing Size on Measured Pressure Distributions

    NASA Technical Reports Server (NTRS)

    Rivers, Natale A.; vanDam, Cornielious P.; Brown, Phillip W.; Rivers, Robert A.

    2001-01-01

    The pressure-belt technique is commonly used to measure pressure distributions on lifting and nonlifting surfaces where flush, through-the-surface measurements are not possible. The belts, made from strips of small-bore, flexible plastic tubing, are surface-mounted by a simple, nondestructive method. Additionally, the belts require minimal installation time, thus making them much less costly to install than flush-mounted pressure ports. Although pressure belts have been used in flight research since the early 1950s, only recently have manufacturers begun to produce thinner, more flexible tubing, and thin, strong adhesive tapes that minimize the installation-induced errors on the measurement of surface pressures. The objective of this investigation was to determine the effects of pressure-belt tubing size on the measurement of pressure distributions. For that purpose, two pressure belts were mounted on the right wing of a single-engine, propeller-driven research airplane. The outboard pressure belt served as a baseline for the measurement and the comparison of effects. Each tube had an outer diameter (OD) of 0.0625 in. The inboard belt was used to evaluate three different tube sizes: 0.0625-, 0.1250-, and 0.1875-in. OD. A computational investigation of tube size on pressure distribution also was conducted using the two-dimensional Multielement Streamtube Euler Solver (MSES) code.

  2. Auditory Contagious Yawning in Humans: An Investigation into Affiliation and Status Effects

    PubMed Central

    Massen, Jorg J. M.; Church, Allyson M.; Gallup, Andrew C.

    2015-01-01

    While comparative research on contagious yawning has grown substantially in the past few years, both the interpersonal factors influencing this response and the sensory modalities involved in its activation in humans remain relatively unknown. Extending upon previous studies showing various in-group and status effects in non-human great apes, we performed an initial study to investigate how the political affiliation (Democrat vs. Republican) and status (high vs. low) of target stimuli influences auditory contagious yawning, as well as the urge to yawn, in humans. Self-report responses and a subset of video recordings were analyzed from 118 undergraduate students in the US following exposure to either breathing (control) or yawning (experimental) vocalizations paired with images of former US Presidents (high status) and their respective Cabinet Secretaries of Commerce (low status). The overall results validate the use of auditory stimuli to prompt yawn contagion, with greater response in the experimental than the control condition. There was also a negative effect of political status on self-reported yawning and the self-reported urge to yawn irrespective of the condition. In contrast, we found no evidence for a political affiliation bias in this response. These preliminary findings are discussed in terms of the existing comparative evidence, though we highlight limitations in the current investigation and we provide suggestions for future research in this area. PMID:26617557

  3. Auditory Contagious Yawning in Humans: An Investigation into Affiliation and Status Effects.

    PubMed

    Massen, Jorg J M; Church, Allyson M; Gallup, Andrew C

    2015-01-01

    While comparative research on contagious yawning has grown substantially in the past few years, both the interpersonal factors influencing this response and the sensory modalities involved in its activation in humans remain relatively unknown. Extending upon previous studies showing various in-group and status effects in non-human great apes, we performed an initial study to investigate how the political affiliation (Democrat vs. Republican) and status (high vs. low) of target stimuli influences auditory contagious yawning, as well as the urge to yawn, in humans. Self-report responses and a subset of video recordings were analyzed from 118 undergraduate students in the US following exposure to either breathing (control) or yawning (experimental) vocalizations paired with images of former US Presidents (high status) and their respective Cabinet Secretaries of Commerce (low status). The overall results validate the use of auditory stimuli to prompt yawn contagion, with greater response in the experimental than the control condition. There was also a negative effect of political status on self-reported yawning and the self-reported urge to yawn irrespective of the condition. In contrast, we found no evidence for a political affiliation bias in this response. These preliminary findings are discussed in terms of the existing comparative evidence, though we highlight limitations in the current investigation and we provide suggestions for future research in this area. PMID:26617557

  4. Investigation of the effect of Mg doping for improvements of optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Caglar, Mujdat; Caglar, Yasemin; Ilican, Saliha

    2016-03-01

    Sol-gel spin coating method was used for the deposition of nanostructured undoped and Mg doped ZnO films. The effects of magnesium incorporation on the crystalline structure were investigated by XRD measurements and the structural deterioration was observed in the crystalline quality of the films with respect to increasing in Mg doping. All the samples exhibited a wurtzite structure. From the scanning electron microscopy (SEM) images obtained to investigate the surface morphology it was detected that an increase in Mg doping caused an improvement on the surface roughness and a reduction in the number of voids on the surface. To evaluate the absorption edges of the produced samples depending on the Mg, different methods were used and according to the obtained results, a shifting towards to high energies for the optical band gap was observed in each method. By using the single oscillator model, developed by DiDomenico and Wemple, the refractive index dispersion of the films was analyzed. Eo and Ed values of the 5% Mg doped film were found to be 5.76 eV and 11.80 eV, respectively. Within the scope of electrical properties, from Hall effect measurements, it was determined that all the films exhibited n-type behavior and the carrier concentration increased from 1.49×1016 to 1.20×1017 cm-3 with increasing Mg doping.

  5. Investigating the Effectiveness of Pictorial Health Warnings in Mauritius: Findings From the ITC Mauritius Survey

    PubMed Central

    Kaai, Susan C.; Fong, Geoffrey T.; Driezen, Pete; Quah, Anne C. K.; Burhoo, Premduth

    2014-01-01

    Introduction: Health warnings on tobacco packages are an effective strategy for informing the public about the harms associated with tobacco use. Most studies investigating the effectiveness of pictorial health warnings (PHWs) on cigarette packages are from high-income countries. This study evaluated the impact of PHWs on smokers’ perceptions and behavior in Mauritius, the first country in the World Health Organization African region to implement PHWs. Methods: Data were drawn from 3 waves of a nationally representative cohort of adult smokers from the International Tobacco Control (ITC) Mauritius Survey (n = 668). Wave 1 was conducted in 2009, 6 months prior to the implementation of PHWs. Waves 2 and 3 were conducted 10–12 months and 20–21 months, respectively, postimplementation. Six established indicators of warning effectiveness were used to evaluate the effect of PHWs on smokers’ perceptions and behavior. Results: All indicators of warning effectiveness (salience, cognitive, and behavioral reactions) and the Label Impact Index, a weighted combination of 4 indicators, increased significantly between Waves 1 and 2. However, between Waves 2 and 3, there was a significant decline in the proportion of smokers who reported “avoiding looking” at labels. Conclusions: This study found that implementation of PHWs in Mauritius significantly enhanced the effectiveness of warnings, illustrating their value for other countries, particularly in Africa, at an early stage in tobacco control. The study also demonstrates the importance of revising PHWs to counteract wearout. The introduction of PHWs in Mauritius clearly demonstrates the benefits of employing an evidence-based approach to strengthen tobacco control policies. PMID:24747120

  6. Investigation of ionospheric effects on SAR Interferometry (InSAR): A case study of Hong Kong

    NASA Astrophysics Data System (ADS)

    Zhu, Wu; Ding, Xiao-Li; Jung, Hyung-Sup; Zhang, Qin; Zhang, Bo-Chen; Qu, Wei

    2016-08-01

    Synthetic Aperture Radar Interferometry (InSAR) has demonstrated its potential for high-density spatial mapping of ground displacement associated with earthquakes, volcanoes, and other geologic processes. However, this technique may be affected by the ionosphere, which can result in the distortions of Synthetic Aperture Radar (SAR) images, phases, and polarization. Moreover, ionospheric effect has become and is becoming further significant with the increasing interest in low-frequency SAR systems, limiting the further development of InSAR technique. Although some research has been carried out, thorough analysis of ionospheric influence on true SAR imagery is still limited. Based on this background, this study performs a thorough investigation of ionospheric effect on InSAR through processing L-band ALOS-1/PALSAR-1 images and dual-frequency Global Positioning System (GPS) data over Hong Kong, where the phenomenon of ionospheric irregularities often occurs. The result shows that the small-scale ionospheric irregularities can cause the azimuth pixel shifts and phase advance errors on interferograms. Meanwhile, it is found that these two effects result in the stripe-shaped features in InSAR images. The direction of the stripe-shaped effects keep approximately constant in space for our InSAR dataset. Moreover, the GPS-derived rate of total electron content change index (ROTI), an index to reflect the level of ionospheric disturbances, may be a useful indicator for predicting the ionospheric effect for SAR images. This finding can help us evaluate the quality of SAR images when considering the ionospheric effect.

  7. Investigation of Aerosol Indirect Effects using a Cumulus Microphysics Parameterization in a Regional Climate Model

    SciTech Connect

    Lim, Kyo-Sun; Fan, Jiwen; Leung, Lai-Yung R.; Ma, Po-Lun; Singh, Balwinder; Zhao, Chun; Zhang, Yang; Zhang, Guang; Song, Xiaoliang

    2014-01-29

    A new Zhang and McFarlane (ZM) cumulus scheme includes a two-moment cloud microphysics parameterization for convective clouds. This allows aerosol effects to be investigated more comprehensively by linking aerosols with microphysical processes in both stratiform clouds that are explicitly resolved and convective clouds that are parameterized in climate models. This new scheme is implemented in the Weather Research and Forecasting (WRF) model, which is coupled with the physics and aerosol packages from the Community Atmospheric Model version 5 (CAM5). A test case of July 2008 during the East Asian summer monsoon is selected to evaluate the performance of the new ZM scheme and to investigate aerosol effects on monsoon precipitation. The precipitation and radiative fluxes simulated by the new ZM scheme show a better agreement with observations compared to simulations with the original ZM scheme that does not include convective cloud microphysics and aerosol convective cloud interactions. Detailed analysis suggests that an increase in detrained cloud water and ice mass by the new ZM scheme is responsible for this improvement. To investigate precipitation response to increased anthropogenic aerosols, a sensitivity experiment is performed that mimics a clean environment by reducing the primary aerosols and anthropogenic emissions to 30% of that used in the control simulation of a polluted environment. The simulated surface precipitation is reduced by 9.8% from clean to polluted environment and the reduction is less significant when microphysics processes are excluded from the cumulus clouds. Ensemble experiments with ten members under each condition (i.e., clean and polluted) indicate similar response of the monsoon precipitation to increasing aerosols.

  8. MO-G-BRF-09: Investigating Magnetic Field Dose Effects in Mice: A Monte Carlo Study

    SciTech Connect

    Rubinstein, A; Guindani, M; Followill, D; Melancon, A; Hazle, J; Court, L

    2014-06-15

    Purpose: In MRI-linac treatments, radiation dose distributions are affected by magnetic fields, especially at high-density/low-density interfaces. Radiobiological consequences of magnetic field dose effects are presently unknown; therefore, preclinical studies are needed to ensure the safe clinical use of MRI-linacs. This study investigates the optimal combination of beam energy and magnetic field strength needed for preclinical murine studies. Methods: The Monte Carlo code MCNP6 was used to simulate the effects of a magnetic field when irradiating a mouse-sized lung phantom with a 1.0cmx1.0cm photon beam. Magnetic field effects were examined using various beam energies (225kVp, 662keV[Cs-137], and 1.25MeV[Co-60]) and magnetic field strengths (0.75T, 1.5T, and 3T). The resulting dose distributions were compared to Monte Carlo results for humans with various field sizes and patient geometries using a 6MV/1.5T MRI-linac. Results: In human simulations, the addition of a 1.5T magnetic field caused an average dose increase of 49% (range:36%–60%) to lung at the soft tissue-to-lung interface and an average dose decrease of 30% (range:25%–36%) at the lung-to-soft tissue interface. In mouse simulations, the magnetic fields had no effect on the 225kVp dose distribution. The dose increases for the Cs-137 beam were 12%, 33%, and 49% for 0.75T, 1.5T, and 3.0T magnetic fields, respectively while the dose decreases were 7%, 23%, and 33%. For the Co-60 beam, the dose increases were 14%, 45%, and 41%, and the dose decreases were 18%, 35%, and 35%. Conclusion: The magnetic field dose effects observed in mouse phantoms using a Co-60 beam with 1.5T or 3T fields and a Cs-137 beam with a 3T field compare well with those seen in simulated human treatments with an MRI-linac. These irradiator/magnet combinations are suitable for preclinical studies investigating potential biological effects of delivering radiation therapy in the presence of a magnetic field. Partially funded by Elekta.

  9. Investigation of Maternal Genotype Effects in Autism by Genome-Wide Association

    PubMed Central

    Yuan, Han; Dougherty, Joseph D.

    2014-01-01

    Lay Abstract Autism spectrum disorders (ASDs) are pervasive developmental disorders which have both a genetic and environmental component. One source of the environmental component is the in utero (prenatal) environment. The maternal genome can potentially contribute to the risk of autism in children by altering this prenatal environment. In this study, the possibility of maternal genotype effects was explored by looking for common variants (single nucleotide polymorphisms, or SNPs) in the maternal genome associated with increased risk of autism in children. We performed a case/control genome-wide association study (GWAS) using mothers of probands as cases and either fathers of probands or normal females as controls, using two collections of families with autism. We did not identify any SNP that reached significance and thus a common variant of large effect is unlikely. However, there was evidence for the possibility of a large number of alleles each carrying a small effect. This suggested that if there is a contribution to autism risk through common-variant maternal genetic effects, it may be the result of multiple loci of small effects. We did not investigate rare variants in this study. Scientific Abstract Like most psychiatric disorders, autism spectrum disorders have both a genetic and an environmental component. While previous studies have clearly demonstrated the contribution of in utero (prenatal) environment on autism risk, most of them focused on transient environmental factors. Based on a recent sibling study, we hypothesized that environmental factors could also come from the maternal genome, which would result in persistent effects across siblings. In this study, the possibility of maternal genotype effects was examined by looking for common variants (single nucleotide polymorphisms, or SNPs) in the maternal genome associated with increased risk of autism in children. A case/control genome-wide association study (GWAS) was performed using mothers of

  10. Atomic force microscopy based investigations of anti-inflammatory effects in lipopolysaccharide-stimulated macrophages.

    PubMed

    Pi, Jiang; Cai, Huaihong; Yang, Fen; Jin, Hua; Liu, Jianxin; Yang, Peihui; Cai, Jiye

    2016-01-01

    A new method based on atomic force microscopy (AFM) was developed to investigate the anti-inflammatory effects of drugs on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The LPS-stimulated RAW264.7 macrophage cell line is a widely used in vitro cell model for the screening of anti-inflammatory drugs or the study of anti-inflammatory mechanisms. In this work, the inhibitory effects of dexamethasone and quercetin on LPS-CD14 receptor binding in RAW264.7 macrophages was probed by LPS-functionalized tips for the first time. Both dexamethasone and quercetin were found to inhibit LPS-induced NO production, iNOS expression, IκBα phosphorylation, and IKKα/β phosphorylation in RAW264.7 macrophages. The morphology and ultrastructure of RAW264.7 macrophages were determined by AFM, which indicated that dexamethasone and quercetin could inhibit LPS-induced cell surface particle size and roughness increase in RAW264.7 macrophages. The binding of LPS and its receptor in RAW264.7 macrophages was determined by LPS-functionalized AFM tips, which demonstrated that the binding force and binding probability between LPS and CD14 receptor on the surface of RAW264.7 macrophages were also inhibited by dexamethasone or quercetin treatment. The obtained results imply that AFM, which is very useful for the investigation of potential targets for anti-inflammatory drugs on native macrophages and the enhancement of our understanding of the anti-inflammatory effects of drugs, is expected to be developed into a promising tool for the study of anti-inflammatory drugs. PMID:26476923

  11. Investigating the effect of transcendental meditation on blood pressure: a systematic review and meta-analysis.

    PubMed

    Bai, Z; Chang, J; Chen, C; Li, P; Yang, K; Chi, I

    2015-11-01

    Some evidence from previous randomized controlled trials and systematic reviews has demonstrated a positive association between hypertension and transcendental meditation (TM). However, other trials and reviews showed the effect of TM on blood pressure (BP) was unclear but did not use subgroup analysis to rigorously investigate this relationship. The American Heart Association has stated that TM is potentially beneficial but did not give a standard indication. The present study explored several subgroup analyses in systematic reviews to investigate the effect of TM on BP. Medline, Embase, Cochrane Library, Web of Science and Chinese BioMedical Literature Database were searched through August 2014. Randomized controlled trials of TM as a primary intervention for BP were included. Two reviewers independently used the Cochrane Collaboration's quality assessment tool to assess each study's quality. Twelve studies with 996 participants indicated an approximate reduction of systolic and diastolic BP of -4.26 mm Hg (95% CI=-6.06, -2.23) and -2.33 mm Hg (95% CI=-3.70, -0.97), respectively, in TM groups compared with control groups. Results from subgroup analysis suggested that TM had a greater effect on systolic BP among older participants, those with higher initial BP levels, and women, respectively. In terms of diastolic BP, it appears that TM might be more efficient in a short-term intervention and with individuals experiencing higher BP levels. However, some biases may have influenced the results, primarily a lack of information about study design and methods of BP measurement in primary studies. PMID:25673114

  12. Investigating the effect of historical treatments on wheat yield over multiple spatial frequencies

    NASA Astrophysics Data System (ADS)

    Milne, A. E.; Castellanos, M. T.; Cartagena, M. C.; Tarquis, A. M.; Lark, R. M.

    2010-03-01

    In this study we use the maximum overlap discrete packet transform (MODWPT) to investigate the impact of historical fertirrigation treatments and cropping on wheat yield. Our objective was to identify the spatial frequencies at which such effects can be detected. Here we consider wheat yield data harvested in consecutive 0.5 m × 0.5 m-sections along the transect. Prior to the wheat crop, a split plot design experiment had been done to investigate the effect of different fertirrigation treatments on melon yield. The wheat transect crossed 9 of the subplots from the melon crop experiment. Each subplot had received a different level of applied nitrogen. The melons were grown at a 1.5 m spacing and will have removed a proportion of the available nitrogen, leaving a soil nitrogen residual. We expect soil properties, such as available nitrogen, to be spatially variable as they result from spatially variable factors operating over multiple orders of spatial frequency. In this example we have good reason to believe this: the applied nitrogen changed from subplot to subplot constituting a low frequency factor, and we expected the removal of nitrogen by the melon crop to be a localized effect in the neighbourhood of the plant therefore constituting a higher frequency factor. We chose to use the MODWPT in this analysis as it is ideally suited to the elucidation of multifrequency processes that are not necessarily stationary in the variance. We show that the applied nitrogen dominates the wheat yield response, and that there is a noticeable contribution to wheat yield variation at the frequency that corresponds to the melon cropping. However the correlation analysis suggests that the relationship between wheat yield and melon positioning is not as straightforward as we might expect and that other influences affect wheat yield variation at this frequency.

  13. Investigation of potential endocrine disrupting effects of mosquito larvicidal Bacillus thuringiensis israelensis (Bti) formulations.

    PubMed

    Maletz, Sibylle; Wollenweber, Marc; Kubiak, Katharina; Müller, Annett; Schmitz, Stefan; Maier, Dieter; Hecker, Markus; Hollert, Henner

    2015-12-01

    Bti is successfully used as a biological control agent for mosquito control. It has proven to be ecological friendly, and thus, is used in ecologically sensitive habitats. Recent investigations of groundwater in Germany have detected estrogenic activity in five consecutive groundwater wells in a region where Bti is applied. Therefore, it was suspected that this compound can act as an environmental xenoestrogen. In the present study, five Bti formulations as well as the active ingredient, VectoBac® TP (TP), were investigated regarding their estrogenic activity using the LYES and ER CALUX® assays. Furthermore, their steroidogenesis disruption properties were studied using the H295R Steroidogenesis Assay. Additionally, field samples from a Bti application area as well as samples from an artificial pond were examined. Three of the Bti formulations and the active ingredient TP showed significant estrogenic activity in the LYES (up to 52 ng·l(-1) estradiol equivalents (EEQ) in the 18-fold concentration) and/or the ER CALUX® (up to 1 ng·EEQ·l(-1) in the 18-fold concentration). In the H295R significant but weak effects with no dose-response-relationship on the production of estradiol, and 21-hydroxyprogesterone (WDG) as well as testosterone (TP) by H295R cells could be observed. The field samples as well as the samples from the artificial pond showed no significant increase of estrogenic activity after application of TP or WDG in the ER CALUX®. With the exception of the controlled laboratory experiments with direct application of Bti to the utilized in vitro test systems the present study did not reveal any significant effects of Bti on endocrine functions that would indicate that the application of Bti could cause adverse endocrine effects to organisms in aquatic ecosystems. Instead, our results support previous studies that the use of Bti products against mosquitos would be safe even for sensitive habitats such as conservation areas. PMID:26254073

  14. Investigating Curricular Effect on the Teaching and Learning of Mathematics in a Cultural Context: Theoretical and Methodological Considerations

    ERIC Educational Resources Information Center

    Cai, Jinfa; Ni, Yujing

    2011-01-01

    This first article of the special issue presents theoretical and methodological considerations about longitudinally investigating curricular effects on the teaching and learning of mathematics in a cultural context. In particular, in this article, we discuss seven issues related to the investigation of curricular effects on the teaching and…

  15. Investigation of a direct effect of nanosecond pulse electric fields on mitochondria

    NASA Astrophysics Data System (ADS)

    Estlack, Larry E.; Roth, Caleb C.; Cerna, Cesario Z.; Wilmink, Gerald J.; Ibey, Bennett L.

    2014-03-01

    The unique cellular response to nanosecond pulsed electric field (nsPEF) exposure, as compared to longer pulse exposure, has been theorized to be due to permeabilization of intracellular organelles including the mitochondria. In this investigation, we utilized a high-throughput oxygen and pH sensing system (Seahorse® XF24 extracellular flux analyzer) to assess the mitochondrial activity of Jurkat and U937 cells after nsPEF. The XF Analyzer uses a transient micro-chamber of only a few μL in specialized cell culture micro-plates to enable oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) to be monitored in real-time. We found that for nsPEF exposures of 10 pulses at 10-ns pulse width and at 50 kV/cm e-field, we were able to cause an increase in OCR in both U937 and Jurkat cells. We also found that high pulse numbers (>100) caused a significant decrease in OCR. Higher amplitude 150 kV/cm exposures had no effect on U937 cells and yet they had a deleterious effect on Jurkat cells, matching previously published 24 hour survival data. These results suggest that the exposures were modulating metabolic activity in cells possibly due to direct effects on the mitochondria themselves. To validate this hypothesis, we isolated mitochondria from U937 cells and exposed them similarly and found no significant change in metabolic activity for any pulse number. In a final experiment, we removed calcium from the buffer solution that the cells were exposed in and found that no significant enhancement in metabolic activity was observed. These results suggest that direct permeabilization of the mitochondria is unlikely a primary effect of nsPEF exposure and calcium-mediated intracellular pathway activation is likely responsible for observed pulse-induced mitochondrial effects.

  16. Metal valences in electron-doped (Sr,La){sub 2}FeTaO{sub 6} double perovskite: A {sup 57}Fe Moessbauer spectroscopy study

    SciTech Connect

    Rautama, E.-L.; Linden, J.; Yamauchi, H.; Karppinen, M.

    2007-02-15

    Substitution of divalent Sr by trivalent La is found to affect the valence states of both of the two B-site cations, Fe and Ta, in the double perovskite oxide (Sr{sub 1-} {sub x} La {sub x} ){sub 2}FeTaO{sub 6}. Moreover, it improves the degree of order of these cations. From {sup 57}Fe Moessbauer spectra the average Fe valence was found to decrease with increasing La substitution level, x. However, the valence of Fe decreased less than expected if the valence of Ta was assumed to remain constant. Hence, we conclude that also the valence of Ta decreases. - Graphical abstract: Both the degree of order and the valence states of Fe and Ta are controlled in the (Sr{sub 1-} {sub x} La {sub x} ){sub 2}FeTaO{sub 6} double perovskite oxide through aliovalent La{sup III}-for-Sr{sup II} substitution.

  17. Innovative instrumentation for mineralogical and elemental analyses of solid extraterrestrial surfaces: The Backscatter Moessbauer Spectrometer/X Ray Fluorescence analyzer (BaMS/XRF)

    NASA Technical Reports Server (NTRS)

    Shelfer, T. D.; Morris, Richard V.; Nguyen, T.; Agresti, D. G.; Wills, E. L.

    1994-01-01

    We have developed a four-detector research-grade backscatter Moessbauer spectrometer (BaMS) instrument with low resolution x-ray fluorescence analysis (XRF) capability. A flight-qualified instrument based on this design would be suitable for use on missions to the surfaces of solid solar-system objects (Moon, Mars, asteroids, etc.). Target specifications for the flight instrument are as follows: mass less than 500 g; volumes less than 300 cu cm; and power less than 2 W. The BaMS/XRF instrument would provide data on the oxidation state of iron and its distribution among iron-bearing mineralogies and elemental composition information. This data is a primary concern for the characterization of extraterrestrial surface materials.

  18. Structure and oscillational motion of /sup 57/Fe atoms in interstitial sites in Al as determined from interference of Moessbauer. gamma. radiation

    SciTech Connect

    Pauling, L.

    1981-12-01

    The first excited site of the /sup 57/Fe atom entrapped in an interstitial site in aluminum, as reported by W. Petry, G. Vogl, and W. Mansel (Phys. Rev. Lett. 45, 1862 (1980)) from a Moessbauer spectroscopic study of a single crystal, is analyzed by consideration of the value of the Hooke's law constant of the Fe-Al bonds obtained from the values for elemental Fe and Al. The eight wavefunctions for the eightfold nearly degenerate excited state are described as 2s1p1d1f hybrids of three-dimensional harmonic oscillator wavefunctions relative to the center of the undistorted Al/sub 6/ octahedron or as localized 1s functions relative to the center of the distorted octahedron. These considerations provide a qualitative understanding of the observations on this system.

  19. A preliminary investigation of the effects of the unified protocol on temperament.

    PubMed

    Carl, Jenna R; Gallagher, Matthew W; Sauer-Zavala, Shannon E; Bentley, Kate H; Barlow, David H

    2014-08-01

    Previous research has shown that two dimensions of temperament referred to as neuroticism/behavioral inhibition (N/BI) and extraversion/behavioral activation (E/BA) are key risk factors in the development and maintenance of anxiety and mood disorders (Brown & Barlow, 2009). Given such findings, these temperamental dimensions may represent promising treatment targets for individuals with emotional disorders; however, to date, few studies have investigated the effects of psychological treatments on temperamental constructs generally assumed to be "stable, inflexible, and pervasive" (American Psychiatric Association, 2000). The present study addresses this gap in the literature by examining the effects of the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP; Barlow et al., 2011), a cognitive-behavioral therapy designed to target core processes of N/BI and E/BA temperaments, in a sample of adults with principal anxiety disorders and a range of comorbid conditions. Results revealed small effects of the UP on N/BI and E/BA compared with a waitlist control group at post-treatment. Additionally, decreases in N/BI and increases in E/BA during treatment were associated with improvements in symptoms, functioning, and quality of life. Findings provide preliminary support for the notion that the UP treatment facilitates beneficial changes in dimensions of temperament. PMID:24933653

  20. Simulation of nonlinear Westervelt equation for the investigation of acoustic streaming and nonlinear propagation effects.

    PubMed

    Solovchuk, Maxim; Sheu, Tony W H; Thiriet, Marc

    2013-11-01

    This study investigates the influence of blood flow on temperature distribution during high-intensity focused ultrasound (HIFU) ablation of liver tumors. A three-dimensional acoustic-thermal-hydrodynamic coupling model is developed to compute the temperature field in the hepatic cancerous region. The model is based on the nonlinear Westervelt equation, bioheat equations for the perfused tissue and blood flow domains. The nonlinear Navier-Stokes equations are employed to describe the flow in large blood vessels. The effect of acoustic streaming is also taken into account in the present HIFU simulation study. A simulation of the Westervelt equation requires a prohibitively large amount of computer resources. Therefore a sixth-order accurate acoustic scheme in three-point stencil was developed for effectively solving the nonlinear wave equation. Results show that focused ultrasound beam with the peak intensity 2470 W/cm(2) can induce acoustic streaming velocities up to 75 cm/s in the vessel with a diameter of 3 mm. The predicted temperature difference for the cases considered with and without acoustic streaming effect is 13.5 °C or 81% on the blood vessel wall for the vein. Tumor necrosis was studied in a region close to major vessels. The theoretical feasibility to safely necrotize the tumors close to major hepatic arteries and veins was shown. PMID:24180802

  1. Investigations of interhydrogen bond dynamical coupling effects in the polarized IR spectra of acetanilide crystals.

    PubMed

    Flakus, Henryk T; Michta, Anna

    2010-02-01

    This Article presents the investigation results of the polarized IR spectra of the hydrogen bond in acetanilide (ACN) crystals measured in the frequency range of the proton and deuteron stretching vibration bands, nu(N-H) and nu(N-D). The basic spectral properties of the crystals were interpreted quantitatively in terms of the "strong-coupling" theory. The model of the centrosymmetric dimer of hydrogen bonds postulated by us facilitated the explanation of the well-developed, two-branch structure of the nu(N-H) and nu(N-D) bands as well as the isotopic dilution effects in the spectra. On the basis of the linear dichroic and temperature effects in the polarized IR spectra of ACN crystals, the H/D isotopic "self-organization" effects were revealed. A nonrandom distribution of hydrogen isotope atoms (H or D) in the lattice was deduced from the spectra of isotopically diluted ACN crystals. It was also determined that identical hydrogen isotope atoms occupy both hydrogen bonds in the dimeric systems, where each hydrogen bond belongs to a different chain. A more complex fine structure pattern of nu(N-H) and nu(N-D) bands in ACN spectra in comparison with the spectra of other secondary amides (e.g., N-methylacetamide) can be explained in terms of the "relaxation" theory of the IR spectra of hydrogen-bonded systems. PMID:20055492

  2. Theoretical and experimental investigations of flow pulsation effects in Coriolis mass flowmeters

    NASA Astrophysics Data System (ADS)

    Svete, A.; Kutin, J.; Bobovnik, G.; Bajsić, I.

    2015-09-01

    An understanding of the effects of flow pulsations on the dynamic behavior of Coriolis flowmeters is very important for their further development. In order to determine the phase difference between the vibrational signals, which represents the basic measurement effect of Coriolis flowmeters, there are many methods that include the proper filtering of all the signal components, except those with frequencies close to the drive frequency. Therefore, an understanding of the phenomenon of exciting the meter at its first natural frequency is very important. The results of a simple, linear, two-degree-of-freedom, lumped-parameter, dynamic model of a flowmeter show that the flow pulsations can degrade the accuracy of such a flowmeter as a result of indirect excitations of the measuring tube at the first natural frequency through the second-order perturbations by means of the Coriolis forces induced in pulsating flow conditions. In order to experimentally investigate these flow pulsation effects, a prototype of a straight-tube Coriolis mass flowmeter was developed to enable the processing of the response signals logged directly from the flow tube's sensors with the dual quadrature demodulation method, and therefore to provide the information available within the phase-difference data. The experimental results show that the flow pulsations upset the meter at its first natural frequency indirectly, as well as directly at the frequency of the pulsations due to the geometric imperfections of the measuring tube.

  3. Investigations of some building materials for γ-rays shielding effectiveness

    NASA Astrophysics Data System (ADS)

    Mann, Kulwinder Singh; Kaur, Baljit; Sidhu, Gurdeep Singh; Kumar, Ajay

    2013-06-01

    For construction of residential and non-residential buildings bricks are used as building blocks. Bricks are made from mixtures of sand, clay, cement, fly ash, gypsum, red mud and lime. Shielding effectiveness of five soil samples and two fly ash samples have been investigated using some energy absorption parameters (Mass attenuation coefficients, mass energy absorption coefficients, KERMA (kinetic energy released per unit mass), HVL, equivalent atomic number and electron densities) firstly at 14 different energies from 81-1332 keV then extended to wide energy range 0.015-15 MeV. The soil sample with maximum shielding effectiveness has been used for making eight fly ash bricks [(Lime)0.15 (Gypsum)0.05 (Fly Ash)x (Soil)0.8-x, where values of x are from 0.4-0.7]. High Purity Germanium (HPGe) detector has been used for gamma-ray spectroscopy. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence (EDXRF) spectrometer. The agreements of theoretical and experimental values of mass attenuation coefficient have been found to be quite satisfactory. It has been verified that common brick possess the maximum shielding effectiveness for wide energy range 0.015-15 MeV. The results have been shown graphically with some useful conclusions for making radiation safe buildings.

  4. Effects of wettability and interfacial nanobubbles on flow through structured nanochannels: an investigation of molecular dynamics

    NASA Astrophysics Data System (ADS)

    Yen, Tsu-Hsu

    2015-12-01

    Solid-fluid boundary conditions are strongly influenced by a number of factors, including the intrinsic properties of the solid/fluid materials, surface roughness, wettability, and the presence of interfacial nanobubbles (INBs). The interconnected nature of these factors means that they should be considered jointly. This paper employs molecular dynamics (MD) simulation in a series of studies aimed at elucidating the influence of wettability in boundary behaviour and the accumulation of interfacial gas. Specifically, we examined the relationship between effective slip length, the morphology of nanobubbles, and wettability. Two methods were employed for the promotion of hydrophobicity between two structured substrates with similar intrinsic contact angles. We also compared anisotropic and isotropic atomic arrangements in the form of graphite and Si(100), respectively. A physical method was employed to deal with variations in surface roughness, whereas a chemical method was used to adjust the wall-fluid interaction energy (ɛwf). We first compared the characteristic properties of wettability, including contact angle and fluid density within the cavity. We then investigated the means by which variations in solid-fluid interfacial wettability affect interfacial gas molecules. Our results reveal that the morphology of INB on a patterned substrate is determined by wettability as well as the methods employed for the promotion of hydrophobicity. The present study also illustrates the means by which the multiple effects of the atomic arrangement of solids, surface roughness, wettability and INB influence effective slip length.

  5. Investigation of Neutral Wind Effects on the Global Joule Heating Rate Using MHD and TI Models

    NASA Astrophysics Data System (ADS)

    Kalafatoglu, E.; Kaymaz, Z.

    2013-12-01

    Precise calculation of global Joule heating rate is a long standing question in thermosphere-ionosphere coupling processes. The absence of the complete and direct, in-situ measurements of the parameters involved in the calculation of Joule heating such as the conductivity of the medium, small-scale variations of electric fields, and neutral winds at the ionospheric heights poses a great uncertainty in its determination. In this work, we study the effects of the neutral wind on the global Joule heating rate. Most of the time, owing to above mentioned difficulties the effects of the neutral wind have been neglected in the calculations. We investigate their effects using BATSRUS MHD model, TIEGCM and GITM. Using horizontal current density, Cowling conductivity, and Pedersen conductivities from the MHD model, we calculate the joule heating rate with and without the neutral wind contribution. We apply the procedure for March 2008 magnetospheric substorm events and quantify the differences to show the neutral wind contribution. We compare the results with those obtained using neutral wind velocities from TIEGCM and GITM models. This way while we compare and demonstrate the discrepancies between the models, we also provide an assessment for the integration of thermospheric and magnetospheric models.

  6. Experimental investigation of added mass effects on a hydrofoil under cavitation conditions

    NASA Astrophysics Data System (ADS)

    De La Torre, O.; Escaler, X.; Egusquiza, E.; Farhat, M.

    2013-05-01

    The influence of leading edge sheet cavitation and supercavitation on the added mass effects experienced by a 2-D NACA0009 truncated hydrofoil has been experimentally investigated in a hydrodynamic tunnel. A non-intrusive excitation and measuring system based on piezoelectric patches mounted on the hydrofoil surface was used to determine the natural frequencies of the fluid-structure system. The appropriate hydrodynamic conditions were selected to generate a range of stable partial cavities of various sizes and also to minimize the effects of other sources of flow noise and vibrations. The main tests were performed for different sigma values under a constant flow velocity of 14m/s and for incident angles of both 1° and 2°. Additionally, a series of experiments in which the hydrofoil was submerged in air, partially and completely submerged in still water and without cavitation at 7 and 14m/s were also performed. The maximum added mass effect occurs with still water. When cavitation appears, the added mass decreases because the cavity length is increased, and the added mass is minimum for supercavitation. A linear correlation is found between the added mass coefficients and the entrained mass that accounts for the mean density of the cavity, its dimensions and its location relative to the specific mode shape deformation.

  7. Investigating relativity using lunar laser ranging - Geodetic precession and the Nordtvedt effect

    NASA Technical Reports Server (NTRS)

    Dickey, J. O.; Newhall, X. X.; Williams, J. G.

    1989-01-01

    The emplacement of retroreflectors on the moon by Apollo astronauts and the Russian Lunakhod spacecraft marked the inception of lunar laser ranging (LLR) and provided a natural laboratory for the study of general relativity. Continuing acquisition of increasingly accurate LLR data has provided enhanced sensitivity to general relativity parameters. Two relativistic effects are investigated in this paper: (1) the Nordtvedt effect, yielding a test of the strong equivalence principle, would appear as a distortion of the geocentric lunar orbit in the direction of the sun. The inclusion of recent LLR data limits the size of any such effect to 3 + or - 4 cm. The sensitivities to the various PPN quantities are also highlighted. (2) the geodetic precession of the lunar perigee is predicted by general relativity as a consequence of the motion of the earth-moon system about the sun; its theoretical magnitude is 19.2 mas/yr. Analysis presented here confirms this value and determines this quality to a 2 percent level.

  8. Molecular dynamics investigation of the effect of copper nanoparticle on the solid contact between friction surfaces

    NASA Astrophysics Data System (ADS)

    Hu, Chengzhi; Bai, Minli; Lv, Jizu; Liu, Hao; Li, Xiaojie

    2014-12-01

    This study investigated the effect of copper (Cu) nanoparticles on the solid contact between friction surfaces by applying a molecular dynamics method to reveal the mechanisms responsible for the favorable friction properties of nanoparticles. Two models were built, which were named model A (without Cu) and model B (with Cu), respectively. The differences in the mechanical properties between these two models were compared. The simulation results demonstrated that the improvement in friction properties by Cu nanoparticles was more obvious at low velocity than at high velocity. At low velocity, a Cu nano-film was formed on the friction surface, which accommodated the velocity gradient and plastic deformation. Due to the good lubrication effect of the nano-film, the plastic deformation, defect structures and friction force of model B were improved compared with model A. Under high velocity conditions, a transfer layer appeared adjacent to the interface in both models. Because of this, the friction forces of the two models decreased with increased velocity. The fluid mechanics theory was used to explain why the friction force in model B was lower than that in model A at high velocity. The effect of the load on friction properties was also analyzed and the results showed that the mechanisms of anti-wear and friction reduction by Cu nanoparticles under a low load were the same as those under a high load.

  9. Numerical and Experimental Investigation of the Effects of Acceleration Disturbances on Microgravity Experiments

    NASA Technical Reports Server (NTRS)

    Ramachandran, Narayanan

    2000-01-01

    Normal vibrational modes on large spacecraft are excited by crew activity, operating machinery, and other mechanical disturbances. Periodic engine burns for maintaining vehicle attitude and random impulse type disturbances also contribute to the acceleration environment of a Spacecraft. Accelerations from these vibrations (often referred to as g-jitter) are several orders of magnitude larger than the residual accelerations from atmospheric drag and gravity gradient effects. Naturally, the effects of such accelerations have been a concern to prospective experimenters wishing to take advantage of the microgravity environment offered by spacecraft operating in low Earth orbit and the topic has been studied extensively, both numerically and analytically. However, these studies have not produced a general theory that predicts the effects of multi-spectral periodic accelerations on a general class of experiments nor have they produced scaling laws that a prospective experimenter could use to assess how his/her experiment might be affected by this acceleration environment. Furthermore, there are no actual flight experimental data that correlates heat or mass transport with measurements of the periodic acceleration environment. The present investigation approaches this problem with carefully conducted terrestrial experiments and rigorous numerical modeling thereby providing comparative theoretical and experimental data. The modeling, it is hoped will provide a predictive tool that can be used for assessing experiment response to Spacecraft vibrations.

  10. Investigation of the Effectiveness of Dynamic Seat in a Black Hawk Flight Simulation

    NASA Technical Reports Server (NTRS)

    Chung, William W. Y.; Bengford, Norm; Perry, Chuck; Nicholson, Bob; Wilkinson, Colin

    2001-01-01

    Low cost alternatives have been sought to provide motion cues in ground-based flight simulators to meet mission objectives. The ability to provide high frequency vibrations makes the dynamic seat attractive to helicopter training applications. Previous studies have found that dynamic seat does enhance the realism of the cockpit and affect pilots' workload. This investigation, conducted under the auspices of the Joint Shipboard Helicopter Integration Process (JSHIP), is using a three degree-of-freedom dynamic seat, i.e., heave, surge, and sway, with limited travels in a research simulator configured as a UH-60 Black Hawk at NASA Ames Research Center. The seat's effectiveness is studied using hover, landing, pirouette, bob-up/bob-down, sidestep, and acceleration/deceleration maneuvers. Seat commands consist of constant vibrations in heave and sway which provide the fundamental vibratory cues. Pilot station accelerations and collective controls provide onset and sustained commands. In addition, transient effects due to translational-lift, collective; and normal acceleration are produced by regulating the magnitude and frequency that depend on the rotor rpm. Results are compared to flight test data and two other ground-based motion systems configurations, i.e., a motion condition with very large motion travels and a motion condition that is comparable with commercial simulator travels. Both subjective and objective data will be analyzed to determine the significance of the motion cueing effect in each system for selected maneuvers.

  11. Investigation of the effects of Aloe barbadensis on rat ovaries: a preliminary study.

    PubMed

    Kosif, Rengin; Aktas, R Gülhan

    2009-12-01

    Effects of Aloe barbadensis, a type of Aloe vera, on ovaries were investigated during pregnancy. A. vera gel, a commercial and nontherapeutic form of A. barbadensis, was used for this purpose. Three groups (one control and two test groups) of female Wistar albino rats with no prior births were studied. Group I was administered 25 mg (140 mg/kg) of A. barbadensis/day both orally and through gavage. A. barbadensis was contained in capsules with 500 mg of soybean oil; therefore Group II was administered 500 mg of soybean oil. Group III was the control group. All three groups were given normal food and water ad libitum. The substance had been administered for 20 days until birth. Ovaries were examined histologically. Vascular increase and the hyperemic form of ovary in the group administered A. barbadensis were notable. Decrease in primary follicle numbers, increase in secondary follicle numbers, and diminishment of secondary follicle diameters occurred in ovaries. The histological changes imply an angiogenesis effect of A. barbadensis and an effect like that of follicle-stimulating hormone in ovaries. PMID:20041799

  12. A Preliminary Investigation of the Effects of the Unified Protocol on Temperament

    PubMed Central

    Carl, Jenna R.; Gallagher, Matthew W.; Sauer-Zavala, Shannon E.; Bentley, Kate H.; Barlow, David H.

    2014-01-01

    Previous research has shown that two dimensions of temperament referred to as neuroticism/behavioral inhibition (N/BI) and extraversion/behavioral activation (E/BA) are key risk factors in the development and maintenance of anxiety and mood disorders (Brown & Barlow, 2009). Given such findings, these temperamental dimensions may represent promising treatment targets for individuals with emotional disorders; however, to date, few studies have investigated the effects of psychological treatments on temperamental constructs generally assumed to be “stable, inflexible, and pervasive” (American Psychiatric Association, 2000). The present study addresses this gap in the literature by examining the effects of the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP; Barlow et al., 2011), a cognitive-behavioral therapy designed to target core processes of N/BI and E/BA temperaments, in a sample of adults with principal anxiety disorders and a range of comorbid conditions. Results revealed small effects of the UP on N/BI and E/BA compared with a waitlist control group at post-treatment. Additionally, decreases in N/BI and increases in E/BA during treatment were associated with improvements in symptoms, functioning, and quality of life. Findings provide preliminary support for the notion that the UP treatment facilitates beneficial changes in dimensions of temperament. PMID:24933653

  13. Portevin-Le Chatelier effect under cyclic loading: experimental and numerical investigations

    NASA Astrophysics Data System (ADS)

    Mazière, M.; Pujol d'Andrebo, Q.

    2015-10-01

    The Portevin-Le Chatelier (PLC) effect is generally evidenced by the apparition of serrated yielding under monotonic tensile loading conditions. It appears at room temperature in some aluminium alloys, around ? in some steels and in many other metallic materials. This effect is associated with the propagation of bands of plastic deformation in tensile specimens and can in some cases lead to unexpected failures. The PLC effect has been widely simulated under monotonic conditions using finite elements and an appropriate mechanical model able to reproduce serrations and strain localization. The occurrence of serrations can be predicted using an analytical stability analysis. Recently, this serrated yielding has also been observed in specimens made of Cobalt-based superalloy under cyclic loading, after a large number of cycles. The mechanical model has been identified in this case to accurately reproduce this critical number of cycle where serrations appear. The associated apparition of localized bands of deformation in specimens and their influence on its failure has also been investigated using finite element simulations.

  14. Investigation of the response of microstructures under the combined effect of mechanical shock and electrostatic forces

    PubMed Central

    Younis, Mohammad I; Miles, Ronald; Jordy, Daniel

    2009-01-01

    There is strong experimental evidence for the existence of strange modes of failure of microelectromechanical systems (MEMS) devices under mechanical shock and impact. Such failures have not been explained with conventional models of MEMS. These failures are characterized by overlaps between moving microstructures and stationary electrodes, which cause electrical shorts. This work presents modeling and simulation of MEMS devices under the combination of shock loads and electrostatic actuation, which sheds light on the influence of these forces on the pull-in instability. Our results indicate that the reported strange failures can be attributed to early dynamic pull-in instability. The results show that the combination of a shock load and an electrostatic actuation makes the instability threshold much lower than the threshold predicted, considering the effect of shock alone or electrostatic actuation alone. In this work, a single-degree-of-freedom model is utilized to investigate the effect of the shock–electrostatic interaction on the response of MEMS devices. Then, a reduced-order model is used to demonstrate the effect of this interaction on MEMS devices employing cantilever and clamped–clamped microbeams. The results of the reduced-order model are verified by comparing with finite-element predictions. It is shown that the shock–electrostatic interaction can be used to design smart MEMS switches triggered at a predetermined level of shock and acceleration. PMID:21720492

  15. Investigating the effects of behavior constructs on academic persistence in engineering, creativity and risk-taking

    NASA Astrophysics Data System (ADS)

    Deanes, Viveca K.

    Increasingly over the last decade, engineering colleges across this nation have conducted research to identify factors that will help them better predict students' academic persistence in engineering. While initial efforts were aimed at predicting those who would graduate, recent efforts have been directed toward predicting who will persist to the second year, as it has been found that a substantial percentage of those who leave engineering do so during their first year. Prior research investigated the predictability of academic persistence using academic credentials such as grade point averages and SAT scores. However, recent research on academic persistence in engineering has suggested differences in students' behavior and students' levels of dissonance-induced stress, rather than differences in academic credentials, may distinguish persisters from non-persisters. One aspect of an individual's behavior, compliance, and behavior-related stress, referred to as dissonance-induced stress, are proposed to have an effect on academic persistence. Research shows compliance (or conformity) is diametrically opposed to creativity, which is essential to leadership and innovation in engineering. A similar relationship is likely to exist between compliance and risk-taking. This research investigated whether behavior and dissonance-induced stress are good predictors of academic persistence in engineering. This research also investigated relationships between behavior, creativity, and risk-taking. Students who were enrolled in a first-year Fundamentals in Engineering course (ENGR 112) were the subjects in this research. The Style Analysis Instrument was used to collect data regarding students' behavioral orientations. The Style Analysis Instrument provides both natural and adapted measures in four dimensions of human behavior: dominance, influence, steadiness, and compliance. The Creativity and Risk-Taking Instrument was used to collect data regarding students' creativity and

  16. Investigation of DC current injection effect on the microwave characteristics of HTS YBCO microstrip resonators

    NASA Astrophysics Data System (ADS)

    Nurgaliev, T.; Blagoev, B.; Mateev, E.; Neshkov, L.; Strbik, V.; Uspenskaya, L.; Nedkov, I.; Chromik, Š.

    2014-03-01

    The DC current injection effect from a ferromagnetic (FM) La0.7Sr0.3MnO3 (LSMO) to a high temperature superconducting (HTS) Y1Ba2Cu3O7-x (YBCO) thin film was investigated by the microwave surface impedance measurements in a FM/HTS structure, formed as a microstrip resonator for improving the sensitivity of the experiments. The quality factor and the resonance frequency of this structure were found to strongly depend on the current strength, injected from the LSMO electrode into the HTS microstrip electrode. The magnetic penetration depth and the quasiparticle conductivity of the HTS component were determined to increase under DC current injection process, which in all probability stimulated breaking of Cooper pairs and led to a decrease of the superfluid concentration and an increase of the normal fluid concentration without significantly affecting the relaxation time of the quasiparticles.

  17. Investigation of Condensation/Clustering Effects on Rayleigh Scattering Measurements in a Hypersonic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Tyler, Charles

    1996-01-01

    Rayleigh scattering, a nonintrusive measurement technique for the measurement of density in a hypersonic wind tunnel, is under investigation at Wright Laboratory's Mach 6 wind tunnel. Several adverse effects, i.e., extraneous scatter off walls and windows, hinder Rayleigh scattering measurements. Condensation and clustering of flow constituents also present formidable obstacles. Overcoming some of these difficulties, measurements have been achieved while the Mach 6 test section was pumped down to a vacuum, as well as for actual tunnel operation for various stagnation pressures at fixed stagnation temperatures. Stagnation pressures ranged from 0.69 MPa to 6.9 MPa at fixed stagnation temperatures of 511, 556, and 611 K. Rayleigh scatter results show signal levels much higher than expected for molecular scattering in the wind tunnel. Even with higher than expected signals, scattering measurements have been made in the flowfield of an 8-degree half-angle blunt nose cone with a nose radius of 1.5 cm.

  18. Investigating the Mpemba Effect: when hot water freezes faster than cold water

    NASA Astrophysics Data System (ADS)

    Ibekwe, R. T.; Cullerne, J. P.

    2016-03-01

    Under certain conditions a body of hot liquid may cool faster and freeze before a body of colder liquid, a phenomenon known as the Mpemba Effect. An initial difference in temperature of 3.2 °C enabled warmer water to reach 0 °C in 14% less time than colder water. Convection currents in the liquid generate a temperature gradient that causes more rapid heat loss by surface radiation and evaporation than obtains for uniform temperature. This more rapid cooling enables the initially warmer liquid to overtake the cooler liquid, reaching 0 °C earlier and freezing first. Liquid cooling under natural convection follows a five-fourths power law (temperature of liquid T , temperature of surroundings {{T}a} , cooling constant k ): \\frac{\\text{d}T}{\\text{d}t}=k{{≤ft(T-{{T}a}\\right)}\\frac{5{4}}} . In this investigation we found that with evaporation this becomes a four-thirds power law:

  19. Investigating the Effectiveness of Teaching Methods Based on a Four-Step Constructivist Strategy

    NASA Astrophysics Data System (ADS)

    Çalik, Muammer; Ayas, Alipaşa; Coll, Richard K.

    2010-02-01

    This paper reports on an investigation of the effectiveness an intervention using several different methods for teaching solution chemistry. The teaching strategy comprised a four-step approach derived from a constructivist view of learning. A sample consisting of 44 students (18 boys and 26 girls) was selected purposively from two different Grade 9 classes in the city of Trabzon, Turkey. Data collection employed a purpose-designed `solution chemistry concept test', consisting of 17 items, with the quantitative data from the survey supported by qualitative interview data. The findings suggest that using different methods embedded within the four-step constructivist-based teaching strategy enables students to refute some alternative conceptions, but does not completely eliminate student alternative conceptions for solution chemistry.

  20. Investigation of the effect of aggregates' morphology on concrete creep properties by numerical simulations

    SciTech Connect

    Lavergne, F.; Sab, K.; Sanahuja, J.; Bornert, M.; Toulemonde, C.

    2015-05-15

    Prestress losses due to creep of concrete is a matter of interest for long-term operations of nuclear power plants containment buildings. Experimental studies by Granger (1995) have shown that concretes with similar formulations have different creep behaviors. The aim of this paper is to numerically investigate the effect of size distribution and shape of elastic inclusions on the long-term creep of concrete. Several microstructures with prescribed size distribution and spherical or polyhedral shape of inclusions are generated. By using the 3D numerical homogenization procedure for viscoelastic microstructures proposed by Šmilauer and Bažant (2010), it is shown that the size distribution and shape of inclusions have no measurable influence on the overall creep behavior. Moreover, a mean-field estimate provides close predictions. An Interfacial Transition Zone was introduced according to the model of Nadeau (2003). It is shown that this feature of concrete's microstructure can explain differences between creep behaviors.

  1. Microgravity research as a tool for the investigation of effects in magnetic fluids

    NASA Astrophysics Data System (ADS)

    Odenbach, Stefan

    1999-07-01

    The magnetic control of ferrofluids, provided by a magnetic volume force acting on the fluid in concurrence to gravitational forces, opens interesting fields for basic as well as application oriented research and for the design of applications using ferrofluids as acting media. The concurrence between magnetic and gravitational force respectively can often, especially in the investigation of new effects in not optimized systems, become a problem for experimental research with magnetic liquids. The possibilities to exclude gravitational forces by using special experimental facilities providing an environment with strongly reduced gravitational acceleration will be discussed, and the special chances for magnetic fluid research will be outlined here. Using a special example - the search for viscoelastic properties in commercial magnetic fluids - the interaction of usual terrestrial and microgravity experiments will be demonstrated.

  2. Investigation of Micro-Scale Architectural Effects on Damage of Composites

    NASA Technical Reports Server (NTRS)

    Stier, Bertram; Bednarcyk, Brett A.; Simon, Jaan W.; Reese, Stefanie

    2015-01-01

    This paper presents a three-dimensional, energy based, anisotropic, stiffness reduction, progressive damage model for composite materials and composite material constituents. The model has been implemented as a user-defined constitutive model within the Abaqus finite element software package and applied to simulate the nonlinear behavior of a damaging epoxy matrix within a unidirectional composite material. Three different composite microstructures were considered as finite element repeating unit cells, with appropriate periodicity conditions applied at the boundaries. Results representing predicted transverse tensile, longitudinal shear, and transverse shear stress-strain curves are presented, along with plots of the local fields indicating the damage progression within the microstructure. It is demonstrated that the damage model functions appropriately at the matrix scale, enabling localization of the damage to simulate failure of the composite material. The influence of the repeating unit cell geometry and the effect of the directionality of the applied loading are investigated and discussed.

  3. A NASTRAN investigation of simulated projectile damage effects on a UH-1B tail boom model

    NASA Technical Reports Server (NTRS)

    Futterer, A. T.

    1980-01-01

    A NASTRAN model of a UH-1B tail boom that had been designed for another project was used to investigate the effect on structural integrity of simulated projectile damage. Elements representing skin, and sections of stringers, longerons and bulkheads were systematically deleted to represent projectile damage. The structure was loaded in a manner to represent the flight loads that would be imposed on the tail boom at a 130 knot cruise. The deflection of four points on the rear of the tail boom relative to the position of these points for the unloaded, undamaged condition of the tail boom was used as a measure of the loss of structural rigidity. The same procedure was then used with the material properties of the aluminum alloys replaced with the material properties of T300/5208 high strength graphite/epoxy fibrous composite material, (0, + or - 45, 90)s for the skin and (0, + or - 45)s for the longerons, stringers, and bulk heads.

  4. An Investigation into the Effect of Aging on the Forming Limit Diagram of 6063 Aluminum Alloy

    SciTech Connect

    Hosseini, S. M.; Hosseimpour, S. J.; Nourouzi, S.; Gorji, A. H.

    2011-01-17

    In this study, the effect of ageing on the forming limit diagram of a commercially available 6063 aluminum alloy has been investigated. For this purpose, initially the specimens have been aged at 200 deg. C and at various times. The hardness tests have been carried out and the hardness-aging time curve has been obtained for this alloy. Moreover, the mechanical properties were determined by tensile test. Then, the forming limit diagrams have been achieved by using the out-of-plane formability test method at four different conditions containing: annealed, under-aged, peak-aged, and over-aged. The results indicate that in comparing with the annealed condition the FLD{sub 0} decreases significantly from the under-aged condition to the peak-aged condition and increases slightly from the peak-aged condition to the over-aged condition.

  5. Numerical and Experimental Investigation of Temperature Effect on Thickness Distribution in Warm Hydroforming of Aluminum Tubes

    NASA Astrophysics Data System (ADS)

    Hashemi, Seyed Jalal; Moslemi Naeini, Hassan; Liaghat, Gholamhosein; Azizi Tafti, Roohollah; Rahmani, Farzad

    2013-01-01

    Reduction of weight and increase of corrosion resistance are among the advantageous applications of aluminum alloys in automotive industry. Producing complicated components with several parts as a uniform part not only increases their strength but also decreases the production sequences and costs. However, achieving this purpose requires sufficient formability of the material. Tube hydroforming is an alternative process to produce complex products. In this process, the higher the material formability the more uniform will be the thickness distribution. In this research, tube hydroforming of aluminum alloy (AA1050) at various temperatures has been investigated numerically to study temperature effect on thickness distribution of final product. Also a warm hydroforming set-up has been designed and manufactured to evaluate numerical results. According to numerical and experimental results in the case of free bulging, unlike the constrained bulging, increase of the process temperature causes more uniform thickness distribution and therefore increases the material formability.

  6. Investigation of the effects of inlet shapes on fan noise radiation

    NASA Technical Reports Server (NTRS)

    Clark, T. L.; Slotboom, D. R.; Vaidya, P. G.

    1981-01-01

    The effect of inlet shape on forward radiated fan tone noise directivities was investigated under experimentally simplified zero flow conditions. Simulated fan tone noise was radiated to the far field through various shaped zero flow inlets. Baseline data were collected for the simplest baffled and unbaffled straight pipe inlets. These data compared well with prediction. The more general inlet shapes tested were the conical, circular, and exponential surfaces of revolution and an asymmetric inlet achieved by cutting a straight pipe inlet at an acute angle. Approximate theories were developed for these general shapes and some comparisons with data are presented. The conical and exponential shapes produced directivities that differed considerably from the baseline data while the circular shape produced directivities similar to the baseline data. The asymmetric inlet produced asymmetric directivities with significant reductions over the straight pipe data for some angles.

  7. Ab initio investigation of light-induced relativistic spin-flip effects in magneto-optics

    NASA Astrophysics Data System (ADS)

    Mondal, Ritwik; Berritta, Marco; Carva, Karel; Oppeneer, Peter M.

    2015-05-01

    Excitation of a metallic ferromagnet such as Ni with an intensive femtosecond laser pulse causes an ultrafast demagnetization within approximately 300 fs. It was proposed that the ultrafast demagnetization measured in femtosecond magneto-optical experiments could be due to relativistic light-induced processes. We perform an ab initio investigation of the influence of relativistic effects on the magneto-optical response of Ni. To this end, first, we develop a response theory formulation of the additional appearing ultrarelativistic terms in the Foldy-Wouthuysen transformed Dirac Hamiltonian due to the electromagnetic field, and second, we compute the influence of relativistic light-induced spin-flip transitions on the magneto-optics. Our ab initio calculations of relativistic spin-flip optical excitations predict that these can give only a very small contribution (≤0.1 %) to the laser-induced magnetization change in Ni.

  8. Investigation of Beam Loading Effects for the Neutrino Factory Muon Accelerator

    SciTech Connect

    J. Pozimski,M. Aslaninejad,C. Bontoiu,S. Berg,Alex Bogacz

    2010-05-01

    The International design study (IDS) study showed that a Neutrino Factory [1] seems to be the most promising candidate for the next phase of high precision neutrino oscillation experiments. One part of the increased precision is due to the fact that in a Neutrino Factory the decay of muons produces a neutrino beam with narrow energy distribution and divergence. The effect of beam loading on the energy distribution of the muon beam in the Neutrino Factory decay rings has been investigated numerically. The simulations have been performed using the baseline accelerator design including cavities for different number of bunch trains and bunch train timing. A detailed analysis of the beam energy distribution expected is given together with a discussion of the energy spread produced by the gutter acceleration in the FFAG and the implications for the neutrino oscillation experiments will be presented.

  9. Investigating the effects of ICT on innovation and performance of European hospitals: an exploratory study.

    PubMed

    Arvanitis, Spyros; Loukis, Euripidis N

    2016-05-01

    Hospitals are making big investments in various types of ICT, so it is important to investigate their effects on innovation and performance. This paper presents an empirical study in this direction, based on data for 743 hospitals from 18 European countries. We specified and estimated econometrically five equations: one for product innovation, one for process innovation and three equations for the three different dimensions of (ICT-enabled) hospital performance. All five equations included various ICT-related variables reflecting ICT infrastructure and a series of important ICT applications, some of them hospital-specific, and some others of general business use, and also ICT personnel (viewed as a kind of 'soft' ICT investment), while the performance equations also included the two innovation measures. PMID:25822165

  10. Theoretical Investigation of Graphene Nanoribbon Field-Effect Transistors Designed for Digital Applications

    NASA Astrophysics Data System (ADS)

    Harada, Naoki; Sato, Shintaro; Yokoyama, Naoki

    2013-09-01

    Nanometer-scale, single-gate graphene nanoribbon Schottky barrier field-effect transistors (FETs) were theoretically investigated using self-consistent atomistic simulation. The device geometry was determined by referring to the International Technology Roadmap for Semiconductors. The target performance levels were the requirements specified in the roadmap for 2024, particularly a maximum leakage current of 0.1 A/m, an on-current of 2017 A/m, and a delay time of 0.13 ps. The device conditions needed to meet these requirements were found to be a bandgap larger than 1.1 eV, a supply voltage of 0.6 V, and a gate length of 7 nm.

  11. Investigation of the effects of inlet shapes on fan noise radiation

    NASA Astrophysics Data System (ADS)

    Clark, T. L.; Slotboom, D. R.; Vaidya, P. G.

    1981-04-01

    The effect of inlet shape on forward radiated fan tone noise directivities was investigated under experimentally simplified zero flow conditions. Simulated fan tone noise was radiated to the far field through various shaped zero flow inlets. Baseline data were collected for the simplest baffled and unbaffled straight pipe inlets. These data compared well with prediction. The more general inlet shapes tested were the conical, circular, and exponential surfaces of revolution and an asymmetric inlet achieved by cutting a straight pipe inlet at an acute angle. Approximate theories were developed for these general shapes and some comparisons with data are presented. The conical and exponential shapes produced directivities that differed considerably from the baseline data while the circular shape produced directivities similar to the baseline data. The asymmetric inlet produced asymmetric directivities with significant reductions over the straight pipe data for some angles.

  12. An investigation of large inhibitors binding to phosphoglycerate kinase and their effect on anion activation.

    PubMed

    Joao, H C; Williams, R J; Littlechild, J A; Nagasuma, R; Watson, H C

    1992-05-01

    This study extends, to a series of larger anions, our earlier investigation of the interaction of the trypanocidal drug suramin and other small negatively charged molecules with yeast phosphoglycerate kinase. 1H-NMR structural studies of phosphoglycerate kinase in the presence of varying concentrations of these large molecules (designed to mimic, at one end, the anionic charge distribution in the substrate 3-phosphoglycerate, while possibly being able to interact across the cleft of the enzyme) including inositol 1,4,5-triphosphate, 4-amino-6-trichloroethenyl-1,3- benzenedisulphonamide, gallic acid and sulphasalazine are described. The anion activation and/or inhibition of the enzyme by these molecules are also reported. Evidence that binding to the general anion site in the 'basic patch' region of the protein may be responsible for either the activating or inhibiting effects, while binding at the hydrophobic (catalytic) site leads to inhibition only is presented. A reaction scheme which explains these observations is given. PMID:1349525

  13. An investigation of the effects of pitch-roll (de)-coupling on helicopter handling qualities

    NASA Technical Reports Server (NTRS)

    Ockier, C. J.; Pausder, H. J.; Blanken, C. L.

    1995-01-01

    An investigation of the effects of pitch-roll coupling on helicopter handling qualities was performed by the US Army and DLR, using a NASA ground-based and a DLR inflight simulator. Over 90 different coupling configurations were evaluated using a roll-axis tracking task. The results show that although the current ADS-33C coupling criterion discriminates against those types of coupling typical of conventionally controlled helicopters, it not always suited for the prediction of handling qualities of helicopters with modern control systems. Based on the observation that high frequency inputs during tracking are used to alleviate coupling, a frequency domain pitch-roll coupling criterion that uses the average coupling ratio between the bandwidth and neutral stability frequency is formulated. This criterion provides a more comprehensive coverage with respect to the different types of coupling and shows excellent consistency.

  14. Preliminary results from the investigation of thermal effects in electrokinetics soil remediation

    SciTech Connect

    Krause, T.R.; Tarman, B.

    1993-10-01

    Electrokinetics is an emerging soil remediation technology. Contaminants are extracted from the soil as a result of a complex set of phenomena that occur when an electric gradient is imposed across a soil-water system. The primary phenomena include electroosmosis, electromigration, and electrophoresis. Secondary phenomena, such as changes in solubility or speciation of various chemical components, may occur as a result of electrically induced changes in the chemical environment of the system. Numerous factors, such as temperature, may affect each of these phenomena and, consequently, the overall process efficiency. We have begun an investigation of thermal effects in the extraction of potassium dichromate from kaolinite soils under conditions of constant saturation and dewatering. Preliminary results suggest that increasing the soil temperature from 21 to 55{degrees}C may decrease the processing time under saturated conditions. However, increasing the soil temperature under dewatering, conditions causes soil cracking, which reduces the overall process efficiency.

  15. Investigation of the effects of different models of nanofluids on their flow and heat transfer characteristics

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    This paper is devoted to an investigation of the influences of thermal radiation on an unsteady, mixed, convection boundary layer flow and the heat transfer over a vertical heated permeable stretching sheet embedded in a porous medium. Different models of the nanofluid based on different formulae for the thermal conductivity and the dynamic viscosity and their effects on the fluid flow and the heat transfer characteristics are discussed. Using the similarity transformation, we transform the governing equations into similarity, non-linear, ordinary differential equations which are solved by employing a numerical shooting technique with a fourth-order Runge-Kutta integration scheme. The obtained results are presented graphically, and the physical aspects of the problem are discussed.

  16. Investigation of Sooting in Microgravity Droplet Combustion: Fuel-Dependent Effects

    NASA Technical Reports Server (NTRS)

    Manzello, Samuel L.; Hua, Ming; Choi, Mun Young

    1999-01-01

    Kumagai and coworkers first performed microgravity droplet combustion experiments [Kumagai, 1957]. The primary goal of these early experiments were to validate simple 'd(sup 2)-law models [Spalding, 1954, Godsave, 1954] Inherent in the 'd(sup 2) -law' formulation and in the scope of the experimental observation is the neglect of sooting behavior. In fact, the influence of sooting has not received much attention until more recent works [Choi et al., 1990; Jackson et al., 1991; Jackson and Avedisian, 1994; Choi and Lee, 1996; Jackson and Avedisian, 1996; Lee et al., 1998]:. Choi and Lee measured soot volume fraction for microgravity droplet flames using full-field light extinction and subsequent tomographic inversion [Choi and Lee, 1996]. In this investigation, soot concentrations were measured for heptane droplets and it was reported that soot concentrations were considerably higher in microgravity compared to the normal gravity flame. It was reasoned that the absence of buoyancy and the effects of thermophoresis resulted in the higher soot concentrations. Lee et al. [1998] performed soot measurement experiments by varying the initial droplet diameter and found marked influence of sooting on the droplet burning behavior. There is growing sentiment that sooting in droplet combustion must no longer be neglected and that "perhaps one of the most important outstanding contributions of (micro)g droplet combustion is the observation that in the absence of asymmetrical forced and natural convection, a soot shell is formed between the droplet surface and the flame, exerting an influence on the droplet combustion response far greater than previously recognized." [Law and Faeth, 1994]. One of the methods that we are exploring to control the degree of sooting in microgravity is to use different fuels. The effect of fuel structure on sooting propensity has been investigated for over-ventilated concentric coflowing buoyant diffusion flames. (Glassman, 1996]. In these

  17. Investigations of Effects of Surface Temperature and Single Roughness Elements on Boundary-Layer Transition

    NASA Technical Reports Server (NTRS)

    Liepmann, Hans W; Fila, Gertrude H

    1947-01-01

    The laminar boundary layer and the position of the transition point were investigated on a heated flat plate. It was found that the Reynolds number of transition decreased as the temperature of the plate is increased. It is shown from simple qualitative analytical considerations that the effect of variable viscosity in the boundary layer due to the temperature difference produces a velocity profile with an inflection point if the wall temperature is higher than the free-stream temperature. This profile is confirmed by measurements. The instability of inflection-point profiles is discussed. Studies of the flow in the wake of large, two-dimensional roughness elements are presented. It is shown that a boundary-layer can separate and reattach itself to the wall without having transition take place.

  18. Comparative Investigation of Blade Lean Effect in Hydrogen-Fueled Combustion Turbine

    NASA Astrophysics Data System (ADS)

    Nakamura, R.; Suzuki, M.; Yamamoto, M.

    2011-09-01

    Recently, environmental problems have been actively researched all over the world. To overcome air pollution and fossil fuel exhaustion, we have been investigating a hydrogen-fueled propulsion system. In the system, hydrogen is injected from the turbine blade and/or vane surface. The system can realize higher power, lighter weight and lower emission than conventional systems. However, there exist many problems for the realization. One of them is the extremely high temperature region appearing on the wall. In the present study, we clarify the effect of blade lean on the generation of high temperature region. The combusting turbulent flowfield around a normal, a compound lean and a reverse compound lean blades are simulated, using RANS and 5-step reduced combustion model. Comparing the numerical results, it is confirmed that compound lean is promising to suppress the high temperature region.

  19. Photochemical decomposition of organic compounds in water after UV-irradiation: investigation of positive mutagenic effects.

    PubMed

    de Veer, I; Moriske, H J; Rüden, H

    1994-06-01

    It should be investigated whether UV-disinfection of natural and contaminated organic substances in surface and drinking water may generate a positive mutagenic effect. Selected organic pesticides (atrazine, simazine, metobromurone, methabenzthiazurone, dichlorprop) and organic compounds naturally present in water (phenylalanine, tyrosine, polysaccharides) were examined in Ames-test (bacterial strains TA 98 and TA 100) and sister chromatid exchange (SCE)-test (V79 cells) before and after UV-irradiation. UV-irradiation with low- and high-pressure mercury vapor lamps was carried out in parallel experiments. Based on results in Ames- and SCE-test a mutagenic activity was not obtained for all samples, neither before nor after UV-irradiation. PMID:8202921

  20. Numerical investigation of tip clearance effects in an axial transonic compressor

    NASA Astrophysics Data System (ADS)

    Ciorciari, R.; Lesser, A.; Blaim, F.; Niehuis, R.

    2012-04-01

    Numerical investigations of the Darmstadt transonic single stage compressor (DTC), in the Rotor1-Stator1 configuration, aimed at advancing the understanding of the effect of different rotor tip gaps and transition modelling on the blade surfaces are presented. Steady three dimensional Reynolds Averaged Navier Stokes (RANS) simulations were performed to obtain the flow fields for the different configurations at different operating conditions using the RANS-Solver TRACE. The stage geometry and the multi-block structured grid were generated by G3DMESH and a grid sensitivity analysis was conducted. For the clearance gap region, a fully gridded special H-grid was chosen. Comparisons were made between the flow characteristic at design speed, representative for a transonic flow regime, and at 65% speed, representative for a subsonic flow regime. The computations were used to analyse the flow phenomena through the tip clearance region for the different configurations and their impact on the performance of the compressor stage.