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Sample records for moessbauer effect investigation

  1. Micromagnetic and Moessbauer spectroscopic investigation of strain-induced martensite in austenitic stainless steel

    SciTech Connect

    Meszaros, I.; Kaldor, M.; Hidasi, B.; Vertes, A.; Czako-Nagy, I.

    1996-08-01

    Strain-induced martensite in 18/8 austenitic stainless steel was studied. Magnetic measurements and Moessbauer spectroscopic investigations were performed to characterize the amount of {alpha}{prime}-martensite due to room-temperature plastic tensile loading. The effects of cold work and annealing heat treatment were explored using magnetic Barkhausen noise, saturation polarization, coercive force, hardness, and conversion electron Moessbauer spectroscopy. The suggested Barkhausen noise measurement technique proved to be a useful quantitative and nondestructive method for determining the ferromagnetic phase ratio of the studied alloy.

  2. 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.

  3. 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.

  4. 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.

  5. Search for the Moessbauer Effect in SILVER-109

    NASA Astrophysics Data System (ADS)

    Rezaie-Serej, Shokrollah

    1992-01-01

    The 88-keV first-excited nuclear state in ^{109}Ag has a mean lifetime of 57.1 sec and a corresponding natural linewidth of 1.15 times 10^{-17 } eV which is nearly six orders of magnitude narrower than the width for the 93-keV 13.2-mu sec state in ^{67}Zn. The 93-keV transition in ^{67}Zn has the narrowest linewidth for which the Mossbauer effect has been observed. The 88-keV transition in ^ {109}Ag is obviously a very difficult case for the observation of the Mossbauer effect and provides a stringent test for exploring the practical limits of inhomogeneous line broadening in real single crystals. In the past, two attempts have produced evidence for the occurrence of the Mossbauer effect in ^{109}Ag. However, more detailed, corroborating results are needed to substantiate such positive results. This dissertation reports the results of a series of self-absorption experiments using ^{109 }Cd-doped single-crystal samples of natural silver to observe the Mossbauer effect in ^ {109}Ag. In addition to measuring the temperature dependence of the 88-keV gamma rays emanating from the samples, the changes in the accompanying x rays were also monitored to account for problems associated with the temperature dependence of the solid angle subtended by the detector. The data were analyzed by a parametric model simulating the experiments. The results of these self-absorption experiments in the vertical geometry indicated a clear, positive Mossbauer effect. The measured effective cross section was only two orders of magnitude smaller than the theoretical value of maximum resonance cross section (4.56 times 10^{-20} cm ^{2}). Such a large effective cross section implies an effective linewidth (neglecting the effect of the gravitational redshift and the ambient magnetic field) approximately 50 times the natural linewidth. This is a surprisingly small amount of broadening which is currently not understood.

  6. 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

  7. 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.

  8. Coal liquefaction process streams characterization and evaluation: Investigation of the forms of sulfur in five Wilsonville resid samples by XAFS and moessbauer spectroscopy

    SciTech Connect

    Huffman, G.P.; Huggins, F.E.; Shah, N. . Consortium for Fossil Fuel Science)

    1992-11-01

    This study demonstrated the feasibility of using XAFS and Moessbauer spectroscopy for the examination of distillation resid materials derived from direct coal liquefaction. The least-squares analysis of the XANES region of the K-shell XAFS spectra was shown to be technique which can be used to determine the sulfur forms in coal liquefaction-derived resid samples. The large amount of pyrrhotite in the resid samples (71 to 99% [plus minus]10% of the total sulfur) interfered with the precise quantitative analysis of the organic sulfur. However, a spectral subtraction routine was successfully used to provide semi-quantitative results for sulfur species other than the pyrrhotite. Moessbauer spectroscopy, considered a more accurate method than XAFS for the quantitative analysis of inorganic iron-sulfur species (pyrite, pyrrhotite, iron sulfates), was successfully used to speciate these materials in the coal liquefaction resids. Further application of XAFS and Moessbauer spectroscopy as process development tools appears justified by these results.

  9. Coal liquefaction process streams characterization and evaluation: Investigation of the forms of sulfur in five Wilsonville resid samples by XAFS and moessbauer spectroscopy

    SciTech Connect

    Huffman, G.P.; Huggins, F.E.; Shah, N.

    1992-11-01

    This study demonstrated the feasibility of using XAFS and Moessbauer spectroscopy for the examination of distillation resid materials derived from direct coal liquefaction. The least-squares analysis of the XANES region of the K-shell XAFS spectra was shown to be technique which can be used to determine the sulfur forms in coal liquefaction-derived resid samples. The large amount of pyrrhotite in the resid samples (71 to 99% {plus_minus}10% of the total sulfur) interfered with the precise quantitative analysis of the organic sulfur. However, a spectral subtraction routine was successfully used to provide semi-quantitative results for sulfur species other than the pyrrhotite. Moessbauer spectroscopy, considered a more accurate method than XAFS for the quantitative analysis of inorganic iron-sulfur species (pyrite, pyrrhotite, iron sulfates), was successfully used to speciate these materials in the coal liquefaction resids. Further application of XAFS and Moessbauer spectroscopy as process development tools appears justified by these results.

  10. 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.

  11. 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.

  12. A Resonance Raman/Iodine Moessbauer Investigation of the Starch-Iodine Structure: Aqueous Solution and Iodine Vapor Preparations.

    DTIC Science & Technology

    1980-03-05

    was then evaporated in a stream of prepurified nitrogen to yield solid 󈧗I. For a source of I, the basic Na 9I solution from Oak Ridge was neutralized...depletion of pentaiodide to form triiodide (eq. (2)). 14 I 5I 3 + 12 (2) Iodine Mdssbauer Studies Further efforts to quantitatively investigate the I...populations 1:1:1 (e.g. distorted triiodide , as in CsI3 2 4 ’ 33) also resulted in poor agreement with the experimental spectrum, i. e., an increase

  13. (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.

  14. 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.

  15. 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

  16. Moessbauer measurements of microstructural change in aged duplex stainless steel

    SciTech Connect

    Kirihigashi, A.; Sakamoto, N.; Yamaoka, T.; Nasu, S.

    1995-08-01

    A duplex stainless steel (ASME SA351 CF8M) has usually been manufactured by a continuous casting technique. It consists of a paramagnetic austenite phase and a ferromagnetic ferrite phase. It has been known that the ferrite phase decomposition occurs in this steel after aging between 300 and 450 C. As a result of phase decomposition, a Fe-rich phase and a Cr-rich phase are produced in the ferrite phase. It is difficult to detect the phase decomposition even by not only optical microscopy but also transmission electron microscopy, since the decomposed structure is very fine. However, Moessbauer measurements that can detect the magnetic hyperfine field of magnetic substance may detect the microstructural change. An averaged magnetic hyperfine field increases in the ferrite phase, due to the production of the Fe-rich phase which has high magnetic hyperfine field. Therefore, the authors investigated the phase decomposition of the duplex stainless steel caused by aging, utilization Moessbauer spectroscopy which has capability of detecting this structural change in the atomic level quantitatively. The authors also investigated the potential of backscattering Moessbauer method for NDE technique.

  17. 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.

  18. a Moessbauer Effect and Fenske-Hall Molecular Orbital Study of the Electronic Properties of Organoiron Clusters.

    NASA Astrophysics Data System (ADS)

    Buhl, Margaret Linn

    The electronic properties of trinuclear iron, tetranuclear iron butterfly, iron-cobalt, and iron-copper clusters have been studied experimentally at 78K by the Mossbauer effect and theoretically by Fenske-Hall molecular orbital calculations. The Mossbauer effect isomer shift is very sensitive to the differences in the iron s-electron densities in these clusters and, as expected, decreases as the sum of the iron 4s Mulliken population and the Clementi and Raimondi effective nuclear charge increases. The molecular orbital wave functions and the Mulliken atomic charges are used to calculate the electric field gradient at the metal nuclei and the iron Mossbauer effect quadrupole splittings. The valence contribution was found to be the major component of the electric field gradient in all the clusters studied. In general the calculated value of Delta E_ {Q} is larger than the observed value, as a result of neglect of the valence Sternheimer factor, R. The metal charge depends upon its electronegativity and upon the nature of its Lewis base ligands. The carbonyl ligand carbon charge becomes more positive as the metal electronegativity increases. The oxygen charge becomes more negative as the anionic cluster charge increases, and in so doing, yields the maximum anionic charge separation. The electronic properties of the terminal carbonyl ligands are similar to those of carbon monoxide, whereas the electronic properties of the bridging carbonyl ligands are similar to those of the carbonyl group found in aldehydes and ketones.

  19. Moessbauer Effect Studies of Crystalline and Amorphous Iron-Based Alloys and of Corrosion Processes at Iron Surfaces.

    NASA Astrophysics Data System (ADS)

    Lin, Mou Ching

    In Part I of this thesis, Mossbauer effect spectroscopy has been used to measure the temperature dependence of the ('57)Fe effective magnetic hyperfine field, H(,eff), and isomer shift, (delta), across the entire Fe(,3)Al(,x)Si(,1 -x) system (0 (LESSTHEQ) x (LESSTHEQ) 1) from77K to the Curie temperature, the latter also being determined from these measurements. The observed dependence of H(,eff) and (delta) on Al concentration can be qualitatively understood in terms of the calculated band structure of Fe(,3)Si. ('57)Fe Mossbauer spectra have been obtained at both liquid nitrogen and room temperatures for a series of metallic glasses Fe(,82)B(,18-x)Be(,x) with 0 (LESSTHEQ) x (LESSTHEQ) 6 in Part II. The width of the probability distribution function of the effective magnetic hyperfine field remains approximately constant at a value of 80 kOe for all samples. However, the most probable value of the effective magnetic hyperfine field at liquid nitrogen temperature initially increases with Be content, but starts to decrease as x exceeds four. The isomer shift has a value of -0.032 mm/sec for samples with x (LESSTHEQ) 4 but changes to -0.050 mm/sec for samples with x > 4. The crystallization products obtained upon annealing the samples were identified. In the last part of this thesis, Mossbauer spectroscopy coupled with electrochemical measurements has been used to study in situ the effects of chloride ions on a passivated iron surface in boric acid-sodium borate buffer solution at a pH of 8.4. The Mossbauer spectrum of the oxide film formed after breakdown of the passive film by aggressive chloride ions consists of a doublet with line-width of 0.51 (+OR-) 0.03 mm/sec, isomer shift of 0.35 (+OR-) 0.02 mm/sec relative to the metallic iron, and quadrupole splitting of 0.79 (+OR-) 0.01 mm/sec. The quadrupole splitting differs from that of the passive film which has line-widths of 0.55 (+OR-) 0.08 mm/sec, an isomer shift of 0.36 (+OR-) 0.01 mm/sec, and a quadrupole

  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. Internal friction and Moessbauer study of C{endash}Cr associates in MANET steel

    SciTech Connect

    Gondi, P.; Gupta, R.; Montanari, R.; Principi, G.; Tata, M.E.

    1997-02-01

    Internal friction and Moessbauer techniques have been used to investigate the structure of C{endash}Cr associates and the arrangement of Fe atoms near them in the Cr martensitic steel MANET subjected to different thermal treatments. After slow rate cooling from the austenitic field, the Moessbauer spectra exhibit, besides the complex magnetic pattern of martensite, a low intensity single attributed to the presence of a Cr-rich b.c.c. phase. In correspondence, the internal friction curves show, among others, a Snoek-type peak due to an elastic processes involving C{endash}Cr associates with 6 Cr atoms. To explain the experimental results a simple structure model is suggested. {copyright} {ital 1997 Materials Research Society.}

  4. Moessbauer and adhesion study of ion beam-modified Fe-PTFE interfaces

    NASA Astrophysics Data System (ADS)

    Ingemarsson, P. Anders; Ericsson, Tore; Wappling, Roger; Possnert, Goran

    Conversion electron Moessbauer spectroscopy was used to study ion beam-induced effects at Fe-PTFE thin film interfaces and to relate these effects to accompanying modifications in adhesion. Irradiation with 16 MeV S-32(3+) ions to doses in the range between 5 x 10 to the 11th and 2 x 10 to the 14th ions/sq cm was carried out before or after deposition of thin Fe-57 layers. For both pre- and post-bombardment, a substantial adhesion enhancement was observed. Associated with this were significant changes in the Moessbauer spectra indicating the formation of Fe-C and Fe-F compounds. This compound formation can be associated with the observed improvement in thin film adhesion.

  5. 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.

  6. 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.

  7. Moessbauer Analysis of Low-Temperature Bainite

    SciTech Connect

    Bruna, P.; Crespo, D.; Garcia-Mateo, C.; Bhadeshia, H.K.D.H.

    2005-04-26

    Low-temperature bainite, obtained by the transformation of austenite at temperatures as low as 200 deg. C for times as large as several days, has been reported to have extraordinary mechanical properties including the highest reported hardness of any bainitic steel. The unusual properties are a consequence of the fine scale of the microstructure, which contains bainite plates with thickness in the range 20-40 nm. The microstructure also contains carbon-enriched retained austenite which contributes to the properties via a number of mechanisms. In this work, the microstructure of a high carbon bainitic steel with Si to avoid cementite precipitation and Co to accelerate the transformation has been studied using Moessbauer spectroscopy for a series of samples transformed isothermally at 200 deg. C for time periods of 26, 34 and 96 hours. The total austenite content is almost identical ({approx}13 wt%) for these samples although the carbon concentrations of the phases differ as a function of transformation time. The austenite increases its carbon content from 5.4 atomic % after 26 h transformation to 6.3 at.% after 96 h, while the final bainitic phase retains about 2.2 at.% of C. These results are consistent with data obtained using atom probe tomography for samples transformed isothermally for 12 days.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Electronic structure properties of neptunium intermetallics under pressure from Moessbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Kalvius, G. M.; Potzel, W.; Zwirner, S.; Gal, J.; Nowik, I.

    1994-10-01

    Electronic structure properties of neptunium intermetallics obtained by the 60 keV Moessbauer resonance in Np-237 in the pressure range up to 9 GPa and at temperatures from 1.5 K to about 150 K together with X-ray determinations of the bulk modulus are discussed. Samples of the NaCl compounds NpX, the Laves phases NpX2 and the AuCu3 materials NpX3 as well as the tetragonal series NpX2S2 have been studied. The volume coefficients of magnetic moment and magnetic transition temperature allow the classification in terms of 5f bandwidth arising either from 5f-5f overlap or hybridization with ligand s, p, or d electrons. The pressure-temperature magnetic phase diagram of some of these compounds has also been investigated. In NpGa3 and NpIn3 we find a preference for ferromagnetic order under reduced volume. Finally we address the question of crystal field interactions and show that even in a somewhat delocalized case (NpAl2) they are decisive in determining the high pressure Moessbauer spectra.

  13. 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.

  14. 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.

  15. Anomalous Moessbauer Fraction in Superparamagnetic Systems.

    NASA Astrophysics Data System (ADS)

    Mohie-Eldin, Mohie-Eldin Yehia

    The biological molecule ferritin and its proven synthetic counterpart polysaccharide iron complex (P.I.C.) have been shown to contain small (<100 ^circ in diameter) antiferromagnetic cores at their centers. Mossbauer studies of these molecules have revealed an anomalous drop in the Mossbauer fraction (f-factor) as the temperature rises above 30^ circK for mammalian ferritin and 60 ^circK for P.I.C. Above the blocking temperature, superparamagnetic relaxation results in the disappearance of hyperfine splitting. This thesis investigates and attempts to resolve this Lamb-Mossbauer f-Factor anomaly in these superparamagnetically relaxing systems. Chapter I deals with a basic review of theories of Mossbauer spectroscopy and superparamagnetism. The analogies in the composition of the two molecules is examined in Chapter II. The long range order technique of magnetization measurements is used in Chapter III to compare magnetic properties of both molecules and to verify the suggestion that the P.I.C. molecule is a good "biomimic" to ferritin based on the identification of ferrihydrite as the major mineral in both, by short range probing techniques such as X-ray diffraction. The anomaly is confirmed in P.I.C.'s Mossbauer spectra in Chapter IV. Different absorbers are used to experimentally investigate the absorber thickness effect on the Mossbauer spectra. The anomaly persists for thin absorbers. Also in Chapter V, data that is treated with FFT procedures to eliminate the thickness effect still exhibit this anomaly. We then investigated the effect of superparamagnetic relaxation on the f-factor. In Chapter VI, spin-lattice relaxation was excluded based upon a calculation of the rate of energy transfer from the spin system to the lattice. We introduce a theory in Chapter VII based on the following process as a plausible explanation of the anomaly: Superparamagnetic relaxation brings about a dynamical displacement of the Mossbauer nucleus through magnetostriction. These

  16. HALL EFFECT INVESTIGATIONS

    DTIC Science & Technology

    INTERMETALLIC COMPOUNDS, *SEMICONDUCTING FILMS, *THIN FILM STORAGE DEVICES, ANTIMONY ALLOYS, CRYSTALLIZATION, ELECTRODES, ELECTROMAGNETIC PROPERTIES, EVAPORATION, HALL EFFECT , HEAT TREATMENT, INDIUM ALLOYS, ELECTRICAL RESISTANCE.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Moessbauer study of iron redox in West Valley glass

    SciTech Connect

    Yaschenko, E.; Salahuddin, H.; Muller, I.S.; Pegg, I.L.; Macedo, P.B.

    1994-12-31

    High-level nuclear wastes at West Valley are high in iron which results in a target glass composition for the vitrification process that contains about 12 wt% Fe{sub 2}O{sub 3}. We have developed a series of high-iron glass formulations (up to 21 wt% Fe{sub 2}O{sub 3}) in order to accommodate all reasonable waste stream variability. An additional process control variable is the glass redox ratio, Fe{sup 2+}/(Fe{sup 2+}+Fe{sup 3+}), since this affects the resultant glass properties including durability, crystallization, glass transition temperature, and melt viscosity. In this study, a range of redox states was obtained by bubbling CO/CO{sub 2} mixtures through the melts. The redox state was determined by Moessbauer spectroscopy and correlations between redox state and CO/CO{sub 2} ratio, flow rate, and time were obtained. Analysis of the spectroscopic data provides additional information on changes in the occupation of tetrahedral and octahedral sites with redox state.

  6. Moessbauer and Positron Annihilation Spectroscopy Applied to WWER-1000 RPV Steels

    SciTech Connect

    Slugen, V.; Lipka, J.; Zeman, A.; Debarberis, L.

    2005-04-26

    Moessbauer spectroscopy (MS) and Positron annihilation spectroscopy (PAS) were applied in the evaluation of the microstructure parameters and degradation processes of nuclear reactor pressure vessel (RPV) steel surveillance specimens. Study was oriented to the material investigation of Russian WWER-1000 steels (15Kh2MNFAA and 12Kh2N2MAA) with higher Ni content (1.26 wt.% in base metal and 1.7 wt.% in weld). For comparison, the WWER-440 weld metal (Sv10KhMFT) without Ni was measured too. Specimens were studied in as received form, after irradiation in LVR-15 experimental reactor to the neutron fluence F(E>0.5 MeV) = 1.47x1024 m-2s-1 and after annealing process in vacuum at 475 deg. C/2h. Changes due to different chemical composition and due to irradiation were registered using MS. Post-irradiation thermal treatment and annealing of defects was well detected by different PAS techniques. Results confirm the hypothesis that Ni affects size (decrease) and distribution (more homogeneous) of the Cu- and P-rich clusters and MxCx carbides.

  7. 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.

  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. 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.

  10. 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

  11. 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.

  12. 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)

  13. 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.

  14. Studies in Moessbauer spectroscopy, neutron activation analysis, x-ray fluorescence

    SciTech Connect

    Nomai, M.

    1985-01-01

    The Moessbauer Effects was employed to study cyclopentadienyliron arene compounds. The isomer shift, delta, in these compounds ranges from 0.206 to 0.257 mm/s relative to /sup 5//sub 7/Co/Cu source and ..delta..E/sub Q/ values are from 1.632 to 1.918 mm/s at liquid nitrogen temperature. Room temperature spectra showed low absorption due to small recoil-free fractions the deltas and ..delta..E/sub Q/s can be correlated with the electron withdrawing effects of the alkyl groups bonded to benzene. In polynuclear aromatic system extending over two benzene rings, electron charge density is difficult to explain. Isomer shifts of PF/sub 6//sup -/ and Fe(NCS)/sub 6//sup 3 -/ are more or less independent of the counteranion, while ..delta..E/sub Q/ is slightly influenced by it. (Fe(arene)Cp)/sub 3//sup +/FE(NCS)/sub 6//sup 3 -/ compounds show only two peaks, with parameters almost identical to the PF/sub 6//sup -/ compounds. An isomer shift peak due to Fe(NCS)/sub 6//sup 3 -/, Fe d/sup 5/ state, is not observed and it is believed to coincide with the second right hand peak of the cation. Experimental procedures and results of hydrogen determination in samples of coal and other comparative samples, e.g., NA/sub 2/EDTA.2H/sub 2/O, in a paraffin moderated thermal neutron flux from 1 ..mu..Ci of /sup 252/Cf source are described. Simple instrumentation is used. Accuracy of about 10% or better is possible with stronger neutron source. Other moderators that were tried, but were unsuccessful, were water and graphite. Factors that can affect the neutron flux and prompt ..gamma..-ray distribution in the samples are H, O, and C concentrations. Results of the determination of uranium and other elements in sandstone uranium samples from Zambia are presented.

  15. An Investigation into Instructor Effectiveness.

    ERIC Educational Resources Information Center

    Phipps, Maurice L.; Claxton, David B.

    1997-01-01

    Describes development of the Instructor Effectiveness Questionnaire (IEQ). Survey of 234 students participating in canoeing and kayaking at the Nantahala Outdoor Center (North Carolina) found that all 17 teachers received high scores, that the IEQ was able to discriminate between more- and less-effective instructors, and that female instructors…

  16. 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

  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. 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.

  1. 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.

  2. 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…

  3. 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

  4. 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.

  5. 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).

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Investigations of Near-Zone Doppler Effects.

    NASA Astrophysics Data System (ADS)

    Prouty, Dale Austen

    Far away from an electromagnetic source the normal Doppler shifts in frequency occur--a red shift for receding and a blue shift for approaching. As indicated by previous work with an infinitesimal dipole, different frequency shifts occur when the source and observer move closer together, into the near-zone. These "near-zone Doppler effects" are investigated for general sources and subsequently two specific examples are presented. The general results show that near-zone shifts are similar to far-zone shifts, but the local phase velocity must be used, i.e. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). In the far zone the phase velocity is the speed of light; in the near zone it differs. Fundamentally, the distance between surfaces of constant phase in the near zone is changed. The surfaces of constant phase for the waves are no longer spherical, but more ellipsoidal or spheroidal, so that a moving observer sees a different frequency shift. Two specific examples are presented to indicate the actual magnitude of near-zone effects. The examples include a prolate spheroidal antenna and a circular aperture. Once the magnitude of the effects is determined, the measurability of near-zone Doppler effects is discussed. The investigation concentrates on Fresnel zone effects due to the measurement problem. Finally, it is shown that for an electrically large wire antenna (the spheroidal example) near-zone Doppler effects are measurable.

  12. Very high pressure Moessbauer spectroscopy using diamond anvil cells

    SciTech Connect

    Pasternak, M.P.; Taylor, R.D.

    1988-01-01

    The technique of generating very high pressure by means of Diamond Anvil Cells (DAC) for Mossbauer Effect applications is outlined. A comprehensive description is presented of the principles of DAC, modification for the use in M/umlt o/ssbauer Spectroscopy (MS), the Merrill--Bassett and Bassett cells, of pressure measurements, of gasketing and collimation, and of hydrostatic media. Examples of /sup 151/Eu, /sup 119/Sn and /sup 129/I are given showing the feasibility of DAC applications in MS. Other isotopes with potential use for high pressure MS using DAC are suggested. 27 refs., 9 figs.

  13. Moessbauer spectroscopy at pressures up to 40 GPa

    SciTech Connect

    Taylor, R.D.; Pasternak, M.P.

    1991-11-20

    Mossbauer spectroscopy (MS) is a viable ``non-contact`` technique applicable to high-pressure, diamond anvil cells (DAC) with samples containing a wide variety of the elements suitable for MS. The convenience and simplicity of diamond anvil cells as a means to obtain static high pressures even into the megabar regime has resulted in a renewed interest in pressure as a complement to the usual physical measurements. However, the required small sample size and the difficulty of communicating with the sample leave only x-ray and optical spectroscopy as the readily available tools. Mossbauer spectroscopy which involves recoil-free, low-energy {gamma} rays, provides a powerful additional technique to study a myriad of physical properties in a DAC. MS concerns a particular isotope and can provide local information on phase changes and hysteresis, isomer shifts, valence, bonding, magnetic and quadrupolar interactions, lattice dynamics, and multiple sites. The Mossbauer effect has been seen in about a hundred isotopic transitions in about forty different elements; many are suitable for DAC-MS, most notably {sup 57}Fe, {sup 119}Sn, {sup 121}Sb, {sup 125}Te, {sup 129}I, {sup 149}Sn, {sup 151}Eu, {sup 161}Dy, {sup 1976}Au, and {sup 237}Np. Since the information available from MS is obtained from analyzing the precise energy profile of the Mossbauer {gamma} ray from a source/absorber combination, no contacts or difficult coupling to the DAC are required. We review a number of salient features of the DAC-MS method and present some examples, including new work on FeI{sub 2}.

  14. 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.

  15. 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.

  16. Moessbauer study of amorphous (FeTM){sub 80}B{sub 20}

    SciTech Connect

    Orue, I.; Plazaola, F.; Fernandez-Gubieda, M.L.; Gutierrez, J.; Barandiaran, J.M.

    1994-03-01

    As-cast ferromagnetic amorphous alloys of nominal composition (FeTM){sub 80}B{sub 20} have been studied by Moessbauer Spectroscopy, being TM one transition metal atom, Ni, Cr, Mo or Pd. A detailed analysis of the isomer shift, IS, and hyperfine field distribution, HFD, at Fe sites is reported in order to achieve some conclusions about the Chemical Short Range Order and the electronic structure in these alloys. HFD changes found in (FeNi)B for Ni rich concentrations suggest the existence of Fe atoms strongly interacting with Ni. Small amounts of Cr and Mo shift the HFD to lower values of hyperfine field, B{sub hf}, while Pd enhances the B{sub hf}.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  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. 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.

  3. Moessbauer study on K/sub 2/Fe/sub 2/(CO)/sub 8/ in an external magnetic field

    SciTech Connect

    Arkhipov, I.L.; Kireev, N.V.; Stukan, R.A.; Yunusov, S.M.

    1988-03-01

    We consider in more detail what changes occur in the Moessbauer parameters when apical and equatorial CO groups are replaced by Fe(CO)/sub 4//sup =/ in the trigonal bipyramidal Fe(CO)/sub 5/ molecule. We use Bancroft's concept of the partial contributions to the quadrupole splitting (QS). The main difference between the HFS parameters for the Moessbauer spectra for the possible structures will be a marked difference in the asymmetry parameters. Here /eta/ can be determined for 1/2 /yields/ 3/2 transitions if there is combined hyperfine magnetic and quadrupole interaction. In a diamagnetic (K/sub 2/Fe/sub 2/(CO)/sub 8/), such combined interaction can occur only from the use of external magnetic fields. The Moessbauer spectra were recorded in an Oxford Instruments cryostat having a superconducting solenoid at 4.2 K without a field or with a longitudinal field of 4.6 T. The spectra show that the EFG tensor for K/sub 2/Fe/sub 2/(CO)/sub 8/ is axially symmetric (/eta/ 0) and that the sign of QS is positive.

  4. 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

  5. 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.

  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. 57Fe- and 119Sn-Moessbauer Studies of Tin Doped Chromium Iron Oxides of Composition {alpha}-Cr2-xFexO3

    SciTech Connect

    Helgason, Oern; Berry, Frank J.; Ren Xiaolin; Moyo, Thomas

    2005-04-26

    Tin-doped iron chromium oxides of composition {alpha}-Cr2-xFexO3 prepared by the calcination of precipitates adopt the corundum-related structure. 57Fe Moessbauer spectroscopy shows the materials to be composed of small superparamagnetic particles and no evidence for a Morin transition was observed above 80K. The supertransferred hyperfine magnetic field at the tin site is shown by 119Sn Moessbauer spectroscopy to be less than that experienced in tin-doped {alpha}-Fe2O3.

  8. An experimental investigation of dynamic ground effect

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    Sixty degree delta wing, F-106B, and XB-70 models 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. Tests results showed that the lift and drag increments in dynamic ground effect were always lower than the 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 approached.

  9. 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

  10. 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.

  11. 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.

  12. 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)

  13. 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…

  14. 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.

  15. Investigation of electromagnetic effects in materials processing

    NASA Astrophysics Data System (ADS)

    Teodorescu, Sorin Gabriel

    A new contactless inductive technique has been developed to evaluate both thermophysical and rheological properties of metals in solid and molten states. This is based on the theory that when a conductor moves in a magnetic field, circulating eddy currents are induced and the opposing mechanical torque created is directly proportional to the electrical conductivity and size of the sample. It was determined that the damping torque T, produced by rotating a sample in a magnetic field, is T=23swLR4 B2 , where s is the electrical conductivity of the sample, w is the angular velocity of the crucible, L and R are the length and radius of the sample, respectively, and B represents the strength of the magnetic induction. The technique was applied to a series of materials, including both pure metals and alloys. The results are in excellent agreement with existing data, and new data for several alloys are presented. The technique can also be used in characterization of microstructural condition for various metals, depending on specific applications. The continuous monitoring of electrical resistivity during heat treatment is sensitive to slight modifications in the metal's microscopic structure like solute content, precipitation hardening, and increasing dislocation densities. Isothermal transformation C-curves for 3024 aluminum-copper alloy were determined based on the electrical resistivity measurements. The C-curves were supplemented with hardness and x-ray diffraction measurements. The results obtained in this investigation were in very good agreement with published literature data. In addition, an electromagnetic-based permanent-magnet probe was designed and tested for monitoring velocity (as well as the temperature) in molten metals. It is shown that, when rotating a molten metal in a DC magnetic field, the azimuthal velocity in the vicinity of the crucible is significantly different from the one in the center, which is evidence of secondary flow induced by the DC

  16. Local environment of iron in heavy ion-irradiated amorphous magnetic oxides by Moessbauer and x-ray absorption spectroscopy

    SciTech Connect

    Studer, F.; Houpert Ch. ); Toulemonde, M. ) Dartyge E. )

    1991-04-01

    Moessbauer and X-ray absorption spectroscopies of some crystallized iron oxides, Fe{sub 2}O{sub 3}, FePO{sub 4}, Fe{sub 3}PO{sub 7}, and SrMn{sub 1.85}Fe{sub 0.15}O{sub 2.5}, the garnet Y{sub 3}Fe{sub 5}O{sub 12}, and the barium hexaferrite BaFe{sub 12}O{sub 19} have been undertaken in order to look at the local order around iron in Y{sub 3}Fe{sub 5}O{sub 12} and BaFe{sub 12}O{sub 19} materials amorphized by irradiation with high energy (27 MeV/n) xenon ions accelerated by GANIL. Simulations of the Moessbauer spectra suggested the presence of fivefold coordinated iron in the amorphous irradiated compounds with a distribution of magnetic interactions due to the variations of the number of iron second neighbors. The XANES spectra at the Fe-K edge confirmed the fivefold coordination of iron in the amorphous ferrites, show that the local structure around iron appears to be similar although the original structures were different, and appear close to the one observed in the Fe{sub 3}PO{sub 7} compound in which iron stands in a trigonal bipyramidal environment.

  17. 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

  18. 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.

  19. 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.

  20. Investigation of Edge Effects in Thermoacoustic Couple Measurements

    DTIC Science & Technology

    1990-12-01

    22 Ill. RESULTS AND DISCUSSION -- 24 A. EDGE EFFECT ........................................................................................... 24...investigate the extent to which irregularities in the temperature difference extend into the plate interior. A. EDGE EFFECT We constructed a TAC (TAC#1) with

  1. 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.

  2. 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}.

  3. 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.

  4. 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…

  5. Plasma effects on Heliac configurations: a preliminary investigation

    SciTech Connect

    Mondt, J.P.

    1983-08-01

    Plasma effects on equilibrium, stability, and transport properties of helical stellarators with a hardcore current through the center (Heliac) are investigated, mainly analytically and with an emphasis on understanding the underlying physics and rough scaling rather than on accuracy and completeness. The presently reported results provide a focus in parameter space for further detailed research on the feasibility of the Heliac concept, as well as some tools with which to carry out such investigations.

  6. 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…

  7. 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…

  8. 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…

  9. 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.

  10. 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.

  11. 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.

  12. 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].

  13. Moessbauer Analysis of Fe94-xNb6Bx (x = 9, 14, 20) Alloys Developed by Mechanical Alloying

    SciTech Connect

    Bruna, P.

    2005-04-26

    The alloys were prepared by milling elemental powders in a planetary ball mill. XRD analysis of the powders indicate that a nanocrystalline heterogeneous bcc alloy was obtained. DSC study of the thermal stability of the powders obtained indicate that some grain growth and reordering of the structure was obtained at temperatures as low as 350 deg. C up to 600 deg. C. Room temperature Transmission Moessbauer spectroscopy from the as milled alloys as well as from the annealed alloys was performed to determine the structure, homogeneity and how the structure changed after annealing at 600 deg. C. The results indicate that the as milled alloys are mainly a crystalline bcc alloy containing most of the Fe, Nb and B. A small amount of a disordered/amorphous phase is also formed for the three alloys. Annealing of the to B richer alloys results in the diffusion of most of the B outside the alloy structure and the crystallization of Fe2B and {alpha}-Fe. Annealing the heterogeneous as-milled powders enhances the separation of Fe rich ({alpha}-Fe ), B rich (Fe2B) and Nb rich regions in the two richer in B alloys studied. On the contrary, the alloy x=9 does not change significantly during annealing.

  14. 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.

  15. 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.

  16. Effectiveness of contact investigations for tuberculosis control in Arkansas

    PubMed Central

    Guzzetta, Giorgio; Ajelli, Marco; Yang, Zhenhua; Mukasa, Leonard N.; Patil, Naveen; Bates, Joseph H.; Kirschner, Denise E.; Merler, Stefano

    2015-01-01

    Comprehensive assessment of the effectiveness of contact investigations for tuberculosis (TB) control is still lacking. In this study, we use a computational model, calibrated against notification data from Arkansas during the period 2001–2011, that reproduces independent data on key features of TB transmission and epidemiology. The model estimates that the Arkansas contact investigations program has avoided 18.6% (12.1–25.9%) of TB cases and 23.7% (16.4–30.6%) of TB deaths that would have occurred during 2001–2014 if passive diagnosis alone were implemented. If contacts of sputum smear-negative cases had not been included in the program, the percentage reduction would have been remarkably lower. In addition, we predict that achieving national targets for performance indicators of contact investigation programs has strong potential to further reduce TB transmission and burden. However, contact investigations are expected to have limited effectiveness on avoiding reactivation cases of latent infections over the next 60 years. PMID:26051196

  17. An Investigation of Magneto-Acoustic Effects in Conductive Fluids.

    DTIC Science & Technology

    1979-12-01

    California AN INVE STIGATION OF #AGNETO-# COUSTIC EFFECTS IN CONDUCTIVE FLUIDS$ by /0Robert Franz/Klaus Thesis Advisor: P.H. Moose Approved for public...NUMIUEN OEM=. 112: L RECIPIENT’S CATALOG MUMER ,. TvITLI ad a ..mbo) L TtP oF REPORT6, P.moo CovEMo0 An Investigation of Magneto-Acoustic Master’s...Thesis; Effects in Conductive Fluids December 1979 6. PERPOUMmD ORe. REPORT NumaI 7. AUTNOR A ) A 0 ANNUM N Robert Franz Klaus 9. P019PPa"ING oNI N0ZATION

  18. Investigation of Systematic Effects in Atmospheric Microthermal Probe Data.

    DTIC Science & Technology

    1992-12-01

    MICROTHERMAL PROBE DATA by Daniel S. Roper December, 1992 Thesis Advisor. Donald L. Walters Approved for public release; distribution is unlimited 93...EFFWS IN ATMOSP RIC MICROTHERMAL PROBE DATA 12. PERSONALAUTHOR(S) Da s. Roper 13s. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (year, moith, day...distribution is unlimited. Investigation of Systematic Effects in Atmospheric Microthermal Probe Data by Daniel S. Roper Captain, United States Army B.S

  19. Applications of Thin Film Interference Filters to the Moessbauer Filtering of Synchrotron Radiation.

    NASA Astrophysics Data System (ADS)

    Hung, Nguyen Viet

    1981-06-01

    Synchrotron radiation produced by high energy storage rings surpasses all natural Mossbauer sources in spectral brightness within a narrow Mossbauer slice ((GAMMA) (TURN) 10('-8) ev) in the 1(ANGSTROM) wavelength region by 2-4 orders of magnitude. Several methods have been suggested to filter out this intense beam of resonant photons, such as nuclear Bragg reflection and time filtering techniques. This thesis investigates a new interference technique for Mossbauer filtering of synchrotron radiation, the impedance matched grazing incidence films introduced by Hannon et al. We extend their initial study to account for photoabsorption and show new possibilities for the suppression of electronic reflection. In particular the impedance matched condition can still be satisfied even though the reflection amplitudes are now complex and the new damping stabilized solutions previously inaccessible in the zero absorption limit were investigated and compared to impedance-matched solutions. Furthermore we consider coating a resonant Fe('59) film on a nonresonant substrate for the impedance matched and damping stabilized cases as well as alternate types of interference filters such as the half wave films and the ultra thin films. Mossbauer isotopes with strong resonant scattering power in addition to FE('57), namely Sn('119) and Dy('161) are explored as very promising materials in the interference filter design. Potential applications of the intense filtered resonant radiation are also discussed. To test the plausibility of the interference filters in the event that the surfaces are less than ideally smooth, a semiquantitative treatment of the effects of surface irregularities on the reflection properties of real surfaces is presented.

  20. 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.

  1. Sustained Effects of Acupuncture Stimulation Investigated with Centrality Mapping Analysis.

    PubMed

    Long, Xiangyu; Huang, Wenjing; Napadow, Vitaly; Liang, Fanrong; Pleger, Burkhard; Villringer, Arno; Witt, Claudia M; Nierhaus, Till; Pach, Daniel

    2016-01-01

    Acupuncture can have instant and sustained effects, however, its mechanisms of action are still unclear. Here, we investigated the sustained effect of acupuncture by evaluating centrality changes in resting-state functional magnetic resonance imaging after manually stimulating the acupuncture point ST36 at the lower leg or two control point locations (CP1 same dermatome, CP2 different dermatome). Data from a previously published experiment evaluating instant BOLD effects and S2-seed-based resting state connectivity was re-analyzed using eigenvector centrality mapping and degree centrality mapping. These data-driven methods might add new insights into sustained acupuncture effects on both global and local inter-region connectivity (centrality) by evaluating the summary of connections of every voxel. We found higher centrality in parahippocampal gyrus and middle temporal gyrus after ST36 stimulation in comparison to the two control points. These regions are positively correlated to major hubs of the default mode network, which might be the primary network affected by chronic pain. The stronger integration of both regions within the whole-brain connectome after stimulation of ST36 might be a potential contributor to pain modulation by acupuncture. These findings highlight centrality mapping as a valuable analysis for future imaging studies investigating clinically relevant outcomes associated with physiological response to acupuncture stimulation.

  2. Sustained Effects of Acupuncture Stimulation Investigated with Centrality Mapping Analysis

    PubMed Central

    Long, Xiangyu; Huang, Wenjing; Napadow, Vitaly; Liang, Fanrong; Pleger, Burkhard; Villringer, Arno; Witt, Claudia M.; Nierhaus, Till; Pach, Daniel

    2016-01-01

    Acupuncture can have instant and sustained effects, however, its mechanisms of action are still unclear. Here, we investigated the sustained effect of acupuncture by evaluating centrality changes in resting-state functional magnetic resonance imaging after manually stimulating the acupuncture point ST36 at the lower leg or two control point locations (CP1 same dermatome, CP2 different dermatome). Data from a previously published experiment evaluating instant BOLD effects and S2-seed-based resting state connectivity was re-analyzed using eigenvector centrality mapping and degree centrality mapping. These data-driven methods might add new insights into sustained acupuncture effects on both global and local inter-region connectivity (centrality) by evaluating the summary of connections of every voxel. We found higher centrality in parahippocampal gyrus and middle temporal gyrus after ST36 stimulation in comparison to the two control points. These regions are positively correlated to major hubs of the default mode network, which might be the primary network affected by chronic pain. The stronger integration of both regions within the whole-brain connectome after stimulation of ST36 might be a potential contributor to pain modulation by acupuncture. These findings highlight centrality mapping as a valuable analysis for future imaging studies investigating clinically relevant outcomes associated with physiological response to acupuncture stimulation. Clinical trial registration: NCT01079689, ClinicalTrials.gov. PMID:27803655

  3. 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}.

  4. 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

  5. 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.

  6. Investigation of the effective field in magnetic fluids

    SciTech Connect

    Smirnov, V.I.

    1986-07-01

    The authors describe investigations of the effective field caused by the orientational interaction between ferroparticles for magnetic fluids with a conducting and a nonconducting base. The magnetic susceptibility of four magnetic fluid specimens was investigated. Specimens consisted of a colloid solution of magnetite in kerosene, stabilized with oleic acid; mercury-based magnetic fluids, a colloid solution of finely dispersed iron particles in mercury, a solution of iron particles with a lower degree of dispersion, and a solution of cobalt particles. Figures show the temperature dependences of the magnetic suceptibility of the fluid specimens. It was shown that under certain conditions, it is possible that instabilities can arise and heterophase impurities can form in accordance with the mechanism proposed previously in both electrically conducting and nonconducting magnetic fluids.

  7. Investigation of the string effect using final state photons

    NASA Astrophysics Data System (ADS)

    Akers, R.; Alexander, G.; Allison, J.; Altekamp, N.; Ametewee, K.; Anderson, K. J.; Anderson, S.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Ball, A. H.; Barberio, E.; Barlow, R. J.; Bartoldus, R.; Batley, J. R.; Beaudoin, G.; Bechtluft, J.; Beck, A.; Beck, G. A.; Beeston, C.; Behnke, T.; Bell, K. W.; Bella, G.; Bentvelsen, S.; Berlich, P.; Bethke, S.; Biebel, O.; Bloodworth, I. J.; Bock, P.; Bosch, H. M.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brown, R. M.; Buijs, A.; Burckhart, H. J.; Burgard, C.; Bürgin, R.; Capiluppi, P.; Carnegie, R. K.; Carter, A. A.; Carter, J. R.; Chang, C. Y.; Charlesworth, C.; Charlton, D. G.; Chu, S. L.; Clarke, P. E. L.; Clayton, J. C.; Clowes, S. G.; Cohen, I.; Conboy, J. E.; Cooke, O. C.; Cuffiani, M.; Dado, S.; Dallapiccola, C.; Dallavalle, G. M.; Darling, C.; de Jong, S.; Del Pozo, L. A.; Deng, H.; Dixit, M. S.; Do Couto E Silva, E.; Duboscq, J. E.; Duchovni, E.; Duckeck, G.; Duerdoth, I. P.; Dunwoody, U. C.; Edwards, J. E. G.; Estabrooks, P. G.; Evans, H. G.; Fabbri, F.; Fabbro, B.; Fanti, M.; Fath, P.; Fiedler, F.; Fierro, M.; Fincke-Keeler, M.; Fischer, H. M.; Folman, R.; Fong, D. G.; Foucher, M.; Fukui, H.; Fürtjes, A.; Gagnon, P.; Gaidot, A.; Gary, J. W.; Gascon, J.; Gascon-Shotkin, S. M.; Geddes, N. I.; Geich-Gimbel, C.; Gensler, S. W.; Gentit, F. X.; Geralis, T.; Giacomelli, G.; Giacomelli, P.; Giacomelli, R.; Gibson, V.; Gibson, W. R.; Gillies, J. D.; Gingrich, D. M.; Goldberg, J.; Goodrick, M. J.; Gorn, W.; Grandi, C.; Gross, E.; Hanson, G. G.; Hansroul, M.; Hapke, M.; Hargrove, C. K.; Hart, P. A.; Hartmann, C.; Hauschild, M.; Hawkes, C. M.; Hawkings, R.; Hemingway, R. J.; Herten, G.; Heuer, R. D.; Hill, J. C.; Hillier, S. J.; Hilse, T.; Hobson, P. R.; Hochman, D.; Homer, R. J.; Honma, A. K.; Howard, R.; Hughes-Jones, R. E.; Hutchcroft, D. E.; Igo-Kemenes, P.; Imrie, D. C.; Jawahery, A.; Jeffreys, P. W.; Jeremie, H.; Jimack, M.; Joly, A.; Jones, M.; Jones, R. W. L.; Jovanovic, P.; Kanzaki, J.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R. K.; Kellogg, R. G.; Kennedy, B. W.; King, B. J.; King, J.; Kirk, J.; Kluth, S.; Kobayashi, T.; Kobel, M.; Koetke, D. S.; Kokott, T. P.; Komamiya, S.; Kowalewski, R.; Kress, T.; Krieger, P.; von Krogh, J.; Kyberd, P.; Lafferty, G. D.; Lafoux, H.; Lahmann, R.; Lai, W. P.; Lanske, D.; Lauber, J.; Layter, J. G.; Lee, A. M.; Lefebvre, E.; Lellouch, D.; Letts, J.; Levinson, L.; Lloyd, S. L.; Loebinger, F. K.; Long, G. D.; Lorazo, B.; Losty, M. J.; Ludwig, J.; Luig, A.; Malik, A.; Mannelli, M.; Marcellini, S.; Markus, C.; Martin, A. J.; Martin, J. P.; Mashimo, T.; Matthews, W.; Mättig, P.; McKenna, J.; McKigney, E. A.; McMahon, T. J.; McNab, A. I.; Meijers, F.; Menke, S.; Merritt, F. S.; Mes, H.; Michelini, A.; Mikenberg, G.; Miller, D. J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Morii, M.; Müller, U.; Nellen, B.; Nijjhar, B.; O'Neale, S. W.; Oakham, F. G.; Odorici, F.; Ogren, H. O.; Oldershaw, N. J.; Oram, C. J.; Oreglia, M. J.; Orito, S.; Palmonari, F.; Pansart, J. P.; Patrick, G. N.; Pearce, M. J.; Phillips, P. D.; Pilcher, J. E.; Pinfold, J.; Plane, D. E.; Poffenberger, P.; Poli, B.; Posthaus, A.; Pritchard, T. W.; Przysiezniak, H.; Redmond, M. W.; Rees, D. L.; Rigby, D.; Rison, M. G.; Robins, S. A.; Rodning, N.; Roney, J. M.; Ros, E.; Rossi, A. M.; Rosvick, M.; Routenburg, P.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D. R.; Sasaki, M.; Sbarra, C.; Schaile, A. D.; Schaile, O.; Scharf, F.; Scharff-Hansen, P.; Schenk, P.; Schmitt, B.; Schröder, M.; Schultz-Coulon, H. C.; Schulz, M.; Schütz, P.; Schwiening, J.; Scott, W. G.; Settles, M.; Shears, T. G.; Shen, B. C.; Shepherd-Themistocleous, C. H.; Sherwood, P.; Siroli, G. P.; Skillman, A.; Skuja, A.; Smith, A. M.; Smith, T. J.; Snow, G. A.; Sobie, R.; Söldner-Rembold, S.; Springer, R. W.; Sproston, M.; Stahl, A.; Starks, M.; Stegmann, C.; Stephens, K.; Steuerer, J.; Stockhausen, B.; Strom, D.; Szymanski, P.; Tafirout, R.; Taras, P.; Tarem, S.; Tecchio, M.; Teixeira-Dias, P.; Tesch, N.; Thomson, M. A.; von Törne, E.; Towers, S.; Tscheulin, M.; Tsukamoto, T.; Turcot, A. S.; Turner-Watson, M. F.; Utzat, P.; van Kooten, R.; Vaseur, G.; Vikas, P.; Vincter, M.; Wäckerle, F.; Wagner, A.; Wagner, D. L.; Ward, C. P.; Ward, D. R.; Ward, J. J.; Watkins, P. M.; Watson, A. T.; Watson, N. K.; Weber, P.; Wells, P. S.; Wermes, N.; Wilkens, B.; Wilson, G. W.; Wilson, J. A.; Wlodek, T.; Wolf, G.; Wotton, S.; Wyatt, T. R.; Yekutieli, G.; Zacek, V.; Zeuner, W.; Zorn, G. T.

    1995-12-01

    The string effect in QCD is investigated using data from the OPAL detector at LEP. By comparing the charged particle flow in three-jet multihadronic events with that in events with two jets and a hard isolated photon, the sensitivity to particular models is reduced. A comparison with various Monte Carlo models is presented. The difference in particle flows in the interquark region is found to be well reproduced by a leading order calculation of soft gluon emission, in the spirit of the Local Parton Hadron Duality hypothesis.

  8. A theoretical investigation of thermodynamic effects on developed cavitation

    NASA Technical Reports Server (NTRS)

    Weir, D. S.

    1976-01-01

    The results of a theoretical investigation of thermodynamic effects on developed cavitation are presented. An approximate solution to the conservation equations for a two-phase laminar boundary layer is obtained. This analysis produces an expression for the temperature difference between the liquid and vapor phases which can be applied to developed cavity flows. Experimental data of cavity temperature depressions are correlated using this result. In addition, a theoretical estimate of the Nusselt number for the cavity is made using a turbulent boundary layer cavity model proposed by Brennen. The result agrees in part with empirically determined expressions for the cavity Nusselt number.

  9. Elasticity and magnetocaloric effect in MnFe4Si3

    DOE PAGES

    Herlitschke, Marcus; Klobes, B.; Sergueev, I.; ...

    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

  10. The homicidol effect: investigating murder as a fitness signal.

    PubMed

    Dahlén, Micael; Söderlund, Magnus

    2012-01-01

    This article extends homicide adaptation theory by investigating signal effects of a murder. In two experiments (N = 299 and N = 161) participants reported their perceptions of a described person. The first study manipulated the information about the person (including or excluding a single sentence stating that the person has committed a murder) and stimulus person/observer sex match (same vs. opposite sex). Results suggest that murder functions as a signal of the described person's fitness that enhances observers' evaluations and inclination to interact with the person. Opposite-sex observers evaluate the murderer's intent more favorably than same-sex observers, but these evaluations of intent produce differential (positive vs. negative) effects between the two groups. The second study replicated the findings and ruled out potential confounds.

  11. 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

  12. Experimental investigation of a wing-in-ground effect craft.

    PubMed

    Tofa, M Mobassher; Maimun, Adi; 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.

  13. Investigation of wing shielding effects on CTOL engine noise

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.

    1979-01-01

    A full scale engine wing shielding investigation was conducted at the Lewis Research Center using a 97,900-N (22,000 lb) thrust turbofan engine and a simulated wing section sized around a conventional-take-off type four-engine narrow body airplane. Sound data were obtained for the wing placed at seven positions in a plane parallel to the engine axis, and were compared to data obtained without the wing at both take off and approach power. In addition, the engine was operated with and without extensive acoustic treatment, including a sonic inlet in order to evaluate wing shielding effectiveness with a highly suppressed engine. The wing shielding effectiveness was also calibrated using a 3.8 cm diam air nozzle as a second source. Results indicated that even though about 10 dB broad band shielding was achieved, the equivalent flyover noise reduction was less than 3.0 EPNdB for most configurations.

  14. 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

  15. 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

  16. Electromyographic investigation of abdominal exercises and the effects of fatigue.

    PubMed

    Robinson, Mark; Lees, Adrian; Barton, Gabor

    Abdominal exercises are widely used to develop the anterior muscles of the trunk. These exercises can be undertaken without the aid of equipment, but increasingly manufacturers are developing equipment which purportedly enhances the training effect for abdominal muscles. As there are many different products and exercises used for abdominal muscle development, it is likely that some are more effective than others. This study aimed to investigate the effectiveness of five commonly performed abdominal exercises. A second aim was to investigate the effects of fatigue on these exercises. Five different types of abdominal exercise [standard crunch (sit-up) with bent knees, gym ball crunch, crunch with 5 kg weight held behind the head, legs raised crunch and a commercially manufactured roller crunch] were examined using integrated surface electromyography (IEMG). The lower rectus abdominis (LRA), upper rectus abdominis (URA) and obliquus externus abdominis (EO) of 15 healthy male participants [age (mean +/- SD) 22.2 +/- 6.8 years; height 1.77 +/- 0.06 m; mass 79.3 +/- 10.7 kg] were monitored using a four-channel special purpose EMG data logger. Three trials of each exercise were performed in random order and normalized to enable comparisons between muscles and exercises. At a later date, ten participants were then re-tested when fresh and after a 30 min whole-body fatigue protocol that specifically targeted the abdominal muscles. Two exercises were evaluated, the abdominal roller crunch and legs raised crunch, which were judged to be the least and most effective, respectively, of the five exercises previously used. The normalized IEMG showed significant (p < 0.001) differences between exercises (gym ball crunch = 86.0 +/- 7.5%; legs raised crunch = 79.9 +/- 5.1%; 5 kg weight crunch = 65.1 +/- 13.4%; standard crunch = 56.2 +/- 3.2%; and roller crunch = 45.0 +/- 11.4%). Post-fatigue, the normalized mean IEMG for both exercises increased significantly (p < 0.05) for LRA and

  17. 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.

  18. 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.

  19. Investigation of drag effect using the field signature method

    NASA Astrophysics Data System (ADS)

    Wan, Zhengjun; Liao, Junbi; Tian, Gui Yun; Cheng, Liang

    2011-08-01

    The potential drop (PD) method is an established non-destructive evaluation (NDE) technique. The monitoring of internal corrosion, erosion and cracks in piping systems, based on electrical field mapping or direct current potential drop array, is also known as the field signature method (FSM). The FSM has been applied in the field of submarine pipe monitoring and land-based oil and gas transmission pipes and containers. In the experimental studies, to detect and calculate the degree of pipe corrosion, the FSM analyses the relationships between the electrical resistance and pipe thickness using an electrode matrix. The relevant drag effect or trans-resistance will cause a large margin of error in the application of resistance arrays. It is the first time that the drag effect in the paper is investigated and analysed in resistance networks with the help of the FSM. Subsequently, a method to calculate the drag factors and eliminate its errors is proposed and presented. Theoretical analysis, simulation and experimental results show that the measurement accuracy can be improved by eliminating the errors caused by the drag effect.

  20. Visual Cueing Effects Investigation for a Hovering Task

    NASA Technical Reports Server (NTRS)

    Chung, William W. Y.; Sweet, Barbara; Kaiser, Mary

    2003-01-01

    In simulators, as in actual aircraft, pilots conduct their missions according to perceived vehicle performance and spatial orientation from out-the-window (OTW) information. Ground-based flight simulations rely upon computer-generated OTW visual scenes. The realism and fidelity of a specific OTW simulation therefore has a significant impact on mission effectiveness. This study investigates effects of three visual parameters of the computer-generated image system (field-of-view, collimation, and resolution) on a disturbance-rejection hovering task. Pilots' performance and workload were studied under the following conditions: collimated optics vs. noncollimated optics, wide field-of-view (FOV) vs. narrow FOV, and higher resolution vs. lower resolution. Subjects were instructed to maintain a station-keeping position during disturbances while piloting an uncoupled four degrees-of-freedom (DOF) helicopter model, which had a satisfactory rate-command system in pitch and roll axes and ideal heading and altitude hold. Display collimation and FOV were found to have significant effects on pilots performance and subjective their subjective perception of visual cueing quality.

  1. 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.

  2. Investigating the Environmental Effects of Ocean Energy Generation (Invited)

    NASA Astrophysics Data System (ADS)

    Copping, A. E.; Anderson, R.; Schultz, I.; Woodruff, D.; Carlson, T.; Ward, J.; van Cleve, F.; Eere Mhk Environmental Effects

    2010-12-01

    damage from specific portions of MHK devices, mooring systems, or electrical cabling. However little is known about the effects of certain MHK stressors such as electromagnetic fields (EMF) from underwater cables and machines, as well as acoustic outputs from rotating turbines. Laboratory investigations into the effects of EMF and acoustics on test organisms will be discussed, and preliminary results presented.

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

    PubMed

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

    2015-08-01

    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.

  4. 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

  5. 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.

  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. 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

  8. 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.

  9. 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.

  10. Investigation of Ultrasonic Wave Scattering Effects using Computational Methods

    NASA Astrophysics Data System (ADS)

    Campbell Leckey, Cara Ann

    2011-12-01

    Advances in computational power and expanded access to computing clusters has made mathematical modeling of complex wave effects possible. We have used multi-core and cluster computing to implement analytical and numerical models of ultrasonic wave scattering in fluid and solid media (acoustic and elastic waves). We begin by implementing complicated analytical equations that describe the force upon spheres immersed in inviscid and viscous fluids due to an incident plane wave. Two real-world applications of acoustic force upon spheres are investigated using the mathematical formulations: emboli removal from cardiopulmonary bypass circuits using traveling waves and the micromanipulation of algal cells with standing waves to aid in biomass processing for algae biofuels. We then move on to consider wave scattering situations where analytical models do not exist: scattering of acoustic waves from multiple scatterers in fluids and Lamb wave scattering in solids. We use a numerical method called finite integration technique (FIT) to simulate wave behavior in three dimensions. The 3D simulations provide insight into experimental results for situations where 2D simulations would not be sufficient. The diverse set of scattering situations explored in this work show the broad applicability of the underlying principles and the computational tools that we have developed. Overall, our work shows that the movement towards better availability of large computational resources is opening up new ways to investigate complicated physics phenomena.

  11. Investigation of the size effect for photonic crystals

    NASA Astrophysics Data System (ADS)

    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.

  12. Morphologic and Pharmacological Investigations in the Epicatechin Gastroprotective Effect

    PubMed Central

    Rozza, A. L.; Hiruma-Lima, C. A.; Tanimoto, A.; Pellizzon, C. H.

    2012-01-01

    Previous studies of the gastroprotective activity of plants have highlighted the importance of the polyphenolic compound epicatechin (EC) in the treatment of gastric ulcers. This paper aimed to evaluate and characterize the gastroprotective mechanism of action of EC using male rats. The gastroprotective action of EC was analyzed in gastric ulcers induced by ethanol or indomethacin. The involvement of sulfhydryl (SH) groups, K+ATP channels, α2 adrenoceptors, gastric antisecretory activity, and the amount of mucus in the development of gastric ulcers were investigated. The lowest effective dose of EC providing gastroprotective effects was 50 mg/kg in the ethanol-induced gastric ulcers and 25 mg/kg in the indomethacin-induced gastric ulcers. The gastroprotection seen upon treatment with EC was significantly decreased in rats pretreated with a SH compound reagent or an α2-receptor antagonist, but not with a K+ATP channel blocker. Furthermore, oral treatment with EC increased mucus production and decreased H+ secretion. Immunohistochemistry demonstrated the involvement of superoxide dismutase (SOD), nitric oxide (NO), and heat shock protein-70 (HSP-70) in the gastroprotection. These results demonstrate that EC provides gastroprotection through reinforcement of the mucus barrier and neutralization of gastric juice and this protection occurs through the involvement of SH compounds, α2-adrenoceptors, NO, SOD, and HSP-70. PMID:22666296

  13. Investigation of Effective Material Properties of Stony Meteorites

    NASA Technical Reports Server (NTRS)

    Agrawal, Parul; Carlozzi, Alex; Bryson, Kathryn

    2016-01-01

    To assess the threat posed by an asteroid entering Earth's atmosphere, one must predict if, when, and how it fragments during entry. A comprehensive understanding of the Asteroid material properties is needed to achieve this objective. At present, the meteorite material found on Earth are the only objects from an entering asteroid that can be used as representative material and be tested inside a laboratory setting. Therefore, unit cell models are developed to determine the effective material properties of stony meteorites and in turn deduce the properties of asteroids. The unit cell is representative volume that accounts for diverse minerals, porosity, and matrix composition inside a meteorite. The various classes under investigation includes H-class, L-class, and LL-class chondrites. The effective mechanical properties such as Young's Modulus and Poisson's Ratio of the unit cell are calculated by performing several hundreds of Monte-Carlo simulations. Terrestrial analogs such as Basalt and Gabbro are being used to validate the unit cell methodology.

  14. The effective method for investigation meridian tropism theory in rats.

    PubMed

    Xu, F Q; Feng, Y Y; Guo, L; Guo, G L; Yan, B L

    2013-01-01

    This present work describes an effective new method for study traditional Chinese medicine (TCM) on meridian tropism (MT) theory, which plays an essential role in clinical selection of TCM according to syndromes and strengthens the therapeutic effects. The new thread included material basis foundation and its tissue distribution study. Xiheliu, the most popular TCM on heart tropism, was investigated by simple and accurate high performance liquid chromatography (HPLC) method. The analysis of plasma after oral administration the total flavonoid of Xiheliu (TFX) exhibited that tamarixetin and kaempferide had the highest concentration and approximately the highest level within 25 min. The mixture of them could last accelerating the urine excretion more than 7 h after a single dose and could not cause the disorder of ion in rats, which was observed in diuretic activity experiment. In view of the reported biological activities was consistent with the effects of Xiheliu, tamarixetin and kaempferide were likely to be the material basis of it. Tissue distribution study showed that the highest level of analytes was in heart, lung, kidney and liver, and most tissues reached maximum level at 30 min post-dose. Since liver was the most important blood-supply tissue, the result of this experiment was in accordance with the MT record of Xiheliu and confirmed that tamarixetin and kaempferide was the material bases of it on MT. This is the first report for the illumination of material basis and the mechanism of Xiheliu on MT by analysis the record of Xiheliu in Compendium of Materia Medica and experimental study.

  15. Experimental investigation on IXV TPS interface effects in Plasmatron

    NASA Astrophysics Data System (ADS)

    Ceglia, Giuseppe; Trifoni, Eduardo; Gouriet, Jean-Baptiste; Chazot, Olivier; Mareschi, Vincenzo; Rufolo, Giuseppe; Tumino, Giorgio

    2016-06-01

    An experimental investigation related to the thermal protection system (TPS) interfaces of the intermediate experimental vehicle has been carried out in the Plasmatron facility at the von Karman Institute for fluid dynamics. The objective of this test campaign is to qualify the thermal behaviours of two different TPS interfaces under flight representative conditions in terms of heat flux and integral heat load ( 180 kW/m2 for 700 s). Three test samples are tested in off-stagnation configuration installed on an available flat plate holder under the same test conditions. The first junction is composed of an upstream ceramic matrix composite (CMC) plate and an ablative P50 cork composite block separated by a gap of 2 mm. The second one is made of an upstream P50 block and a downstream ablative SV2A silicon elastomer block with silicon-based filler in between. A sample composed of P50 material is tested in order to obtain reference results without TPS interface effect. The overheating at the CMC-P50 interface due to the jump of the catalytic properties of the materials, and the recession/swelling behaviour of the P50-SV2A interface are under investigation. All the test samples withstand relatively well the imposed heat flux for the test duration. As expected, both the ablative materials undergo a thermal degradation. The P50 exhibits the formation of a porous char layer and its recession; on the other hand, the SV2A swells and forms a fragile char layer.

  16. Investigating word class effects in first and second languages.

    PubMed

    Furtner, Marco R; Rauthmann, John F; Sachse, Pierre

    2011-08-01

    According to Zyzik in 2009, only a few recent studies have investigated similarities in use of words in comprehension of first languages (L1) and second languages (L2). Furtner, Rauthmann, and Sachse showed a rank order of word classes by frequency of eye-gaze regression when reading other difficult words: nouns, adjectives, closed-class words, verbs. The hypothesis was that a L1-L2 word-class similarity effect between German (L1) and English (L2) would occur, and this was tested with jumbled word reading of English text (wherein letters within words Shave been jumbled) and eye-tracking by 141 participants. Analyses of regressive fixations from one word class to others showed that nouns were regressed most often and there was a rank order of importance among the word classes apparently used to enhance comprehension of other difficult words (nouns, adjectives, verbs, dosed-class words). Thus, previous findings for L1 were largely replicated. Findings are discussed regarding language acquisition.

  17. Investigations on Size Effects of Zerodur®

    NASA Astrophysics Data System (ADS)

    Behar-Lafenetre, S.; Cornillon, L.; Ait-Zaid, S.; Rancurel, M.

    2014-06-01

    Zerodur® is a well-known glass-ceramic used for optical components because of its unequalled stability under thermal environment (due to its extremely low Coefficient of Thermal Expansion). In particular it has been used since decades in Thales Alenia Space's optical payloads for space telescopes, especially for primary mirrors.The drawback of Zerodur® however is its quite low strength: 10 MPa is historically used as a rule of thumb. However, as performance of space telescopes is increasing, an optimization of the design is necessary and therefore an increase of the strength limit taken into account in the calculations.Thales Alenia Space is therefore currently investigating the so-called "size effect" on Zerodur® (see Weibull theory), under CNES funding, with the aim of re- estimating the lower bound of Zerodur® strength.For this, a complete test campaign has been defined with a high number of samples in order to reduce uncertainties. This article presents the first results obtained.

  18. Computational Investigation of the Aerodynamic Effects on Fluidic Thrust Vectoring

    NASA Technical Reports Server (NTRS)

    Deere, K. A.

    2000-01-01

    A computational investigation of the aerodynamic effects on fluidic thrust vectoring has been conducted. Three-dimensional simulations of a two-dimensional, convergent-divergent (2DCD) nozzle with fluidic injection for pitch vector control were run with the computational fluid dynamics code PAB using turbulence closure and linear Reynolds stress modeling. Simulations were computed with static freestream conditions (M=0.05) and at Mach numbers from M=0.3 to 1.2, with scheduled nozzle pressure ratios (from 3.6 to 7.2) and secondary to primary total pressure ratios of p(sub t,s)/p(sub t,p)=0.6 and 1.0. Results indicate that the freestream flow decreases vectoring performance and thrust efficiency compared with static (wind-off) conditions. The aerodynamic penalty to thrust vector angle ranged from 1.5 degrees at a nozzle pressure ratio of 6 with M=0.9 freestream conditions to 2.9 degrees at a nozzle pressure ratio of 5.2 with M=0.7 freestream conditions, compared to the same nozzle pressure ratios with static freestream conditions. The aerodynamic penalty to thrust ratio decreased from 4 percent to 0.8 percent as nozzle pressure ratio increased from 3.6 to 7.2. As expected, the freestream flow had little influence on discharge coefficient.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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"…

  5. 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.

  6. 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.

  7. Experimental Investigation of a Lift Augmented Ground Effect Platform

    DTIC Science & Technology

    2005-09-01

    10 Section 5 - Coanda Effect ............................................................................................ 11...11 Figure 9: Coanda effect : entrainment of air into the jet and jet deflection towards the...rotational velocity out of ground effect ............................... 36 Figure 27: Percentage difference in lift between Coanda nozzles and straight

  8. [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.

  9. 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.

  10. 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.

  11. 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.

  12. A Multilevel Investigation of Neighborhood Effects on Parental Warmth

    ERIC Educational Resources Information Center

    Tendulkar, Shalini A.; Buka, Stephen; Dunn, Erin C.; Subramanian, S. V.; Koenen, Karestan C.

    2010-01-01

    Although researchers recognize that social contexts shape parenting behaviors, the relationship between neighborhood environment and parenting remains poorly understood. To address this gap, we investigated the associations between compositional and contextual (structural, social, and safety) characteristics of neighborhoods and parental warmth.…

  13. 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…

  14. Chemistry in crime investigation: sodium percarbonate effects on bloodstains detection.

    PubMed

    Castelló, Ana; Francés, Francesc; Verdú, Fernando

    2012-03-01

    Chemistry plays a leading role in crime investigation. In the study of bloodstains, chemical reactions provide the means for the detection. All these procedures have been thoroughly studied. However, recently, a new source of error has been found: washing stains with "active oxygen" detergents abrogates presumptive and human hemoglobin tests for bloodstains (although visible). The aim of this investigation was to evaluate the ability of pure sodium percarbonate-main component of detergents-to abrogate presumptive and human hemoglobin tests. Then, a solution to this problem could be found. The results demonstrate that pure sodium percarbonate-itself-is able to abrogate all tests, as well as the different degrees to which each of them is affected by the product. Consequently, faced with a stain of bloody appearance, even the preliminary tests are negative; it is advisable to analyze the DNA. Otherwise, the opportunity of obtaining valuable information is lost.

  15. Investigation of OMA formation and the effect of minerals.

    PubMed

    Zhang, Haiping; Khatibi, Mona; Zheng, Ying; Lee, Kenneth; Li, Zhengkai; Mullin, Joseph V

    2010-09-01

    Oil-mineral-aggregates (OMA) have been shown to be effective in oil spills cleanup. Experimental work was carried out to study the effects of physical-chemical properties of natural minerals and chemically modified minerals on OMA formation and oil removal. The results showed that the hydrophobicity, particle sizes and specific surface of minerals played an important role in OMA formation. Appropriate hydrophobicity of minerals can enhance the formation of OMA. The surface property of minerals can also influence the shape of OMA. Spherical mineral-oil aggregates were frequently formed with hydrophilic minerals while irregular shaped OMA were observed with hydrophobic minerals. The sizes of OMA also increased when the minerals changed from hydrophilic to hydrophobic. The effects of dispersant and mixing energy were also carefully studied. The results showed that dispersant were a dominant factor. When dispersant was applied, effects of other factors became minimal.

  16. 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)

  17. Investigation in vitro of the chromosomal effects of misonidazole

    SciTech Connect

    Schwartz, L.E.; Geard, C.R.; Miller, R.C.

    1980-07-01

    A range of endpoints relating to the DNA damaging effect of misonidazole have been examined in mouse C3H10T1/2 cells with the aim of assessing long term potential deleterious effects on normal cells. Sister chromatid exchanges, chromosomal aberrations, mitotic indices, cell doubling times, and cell inactivation are only dramatically effected at misonidazole concentrations above 3 mM and at comparatively long contact times (greater than 24 hours). At a concentration of 1 mM there is a near linear increase in the frequency of oncogenic transformation up to 6 days contact time. At a 1 mM drug concentration and 24 hour contact time, a regime which may represent the maximum that is clinically achievable, there are 0.02% transformations, sister chromatid exchanges are 5% over control level, over 90% of cells are both free of chromosomal aberrations and are survivors, and there is no difference from control in the rate of progression through the cell cycle. These effects are comparatively trivial in relation to the effects of chemotherapeutic agents that are known carcinogens, however, the 0.02% transformation is equivalent to that which can be achieved in vitro after 80 to 100 rad low LET radiation, hence caution is still advised when considering the long term effects of misonidazole in clinical usage.

  18. Anxiety, inhibition, efficiency, and effectiveness. An investigation using antisaccade task.

    PubMed

    Derakshan, Nazanin; Ansari, Tahereh L; Hansard, Miles; Shoker, Leor; Eysenck, Michael W

    2009-01-01

    Effects of anxiety on the antisaccade task were assessed. Performance effectiveness on this task (indexed by error rate) reflects a conflict between volitional and reflexive responses resolved by inhibitory processes (Hutton, S. B., & Ettinger, U. (2006). The antisaccade task as a research tool in psychopathology: A critical review. Psychophysiology, 43, 302-313). However, latency of the first correct saccade reflects processing efficiency (relationship between performance effectiveness and use of resources). In two experiments, high-anxious participants had longer correct antisaccade latencies than low-anxious participants and this effect was greater with threatening cues than positive or neutral ones. The high- and low-anxious groups did not differ in terms of error rate in the antisaccade task. No group differences were found in terms of latency or error rate in the prosaccade task. These results indicate that anxiety affects performance efficiency but not performance effectiveness. The findings are interpreted within the context of attentional control theory (Eysenck, M. W., Derakshan, N., Santos, R., & Calvo, M. G. (2007). Anxiety and cognitive performance: Attentional control theory. Emotion, 7 (2), 336-353).

  19. Investigating the effect of ethnicity on IVF outcome.

    PubMed

    Dhillon, Rima K; Smith, Paul P; Malhas, Rosamund; Harb, Hoda M; Gallos, Ioannis D; Dowell, Ken; Fishel, Simon; Deeks, Jon J; Coomarasamy, Aravinthan

    2015-09-01

    Success rates for IVF among women from different ethnic groups have been inconclusive. In this study, the relationship between ethnicity and IVF outcome was investigated. Results of a cohort study analysing 13,473 first cycles were compared with the results of meta-analysed data from 16 published studies. Adjustment was made for age, body-mass index, cause of infertility, duration of infertility, previous live birth, previous spontaneous abortion and number of embryos transferred. Black and South Asian women were found to have lower live birth rates compared with White women: Black versus White (OR 0.42 [0.25 to 0.70]; P = 0.001); South Asian versus White (OR 0.80 [0.65t o 0.99]; P = 0.04). Black women had significantly lower clinical pregnancy rates compared with White women (OR 0.41 [0.25 to 9 0.67]; P < 0.001). The meta-analysed results also showed that Black and South Asian women had statistically significant reduced odds of live birth (OR 0.62 [0.55 to 0.71); P < 0.001 and OR 0.66 [0.52 to 0.85); P = 0.001, respectively). Black and South Asian women seem to have the poorest outcome, which is not explained by the commonly known confounders. Future research needs to investigate the possible explanations for this difference and improve IVF outcome for all women.

  20. Effectiveness of single-nucleotide polymorphisms to investigate cattle rustling.

    PubMed

    Fernández, María E; Rogberg-Muñoz, Andrés; Lirón, Juan P; Goszczynski, Daniel E; Ripoli, María V; Carino, Mónica H; Peral-García, Pilar; Giovambattista, Guillermo

    2014-11-01

    Short tandem repeats (STR)s have been the eligible markers for forensic animal genetics, despite single-nucleotide polymorphisms (SNP)s became acceptable. The technology, the type, and amount of markers could limit the investigation in degraded forensic samples. The performance of a 32-SNP panel genotyped through OpenArrays(TM) (real-time PCR based) was evaluated to resolve cattle-specific forensic cases. DNA from different biological sources was used, including samples from an alleged instance of cattle rustling. SNPs and STRs performance and repeatability were compared. SNP call rate was variable among sample type (average = 80.18%), while forensic samples showed the lowest value (70.94%). The repeatability obtained (98.7%) supports the used technology. SNPs had better call rates than STRs in 12 of 20 casework samples, while forensic index values were similar for both panels. In conclusion, the 32-SNPs used are as informative as the standard bovine STR battery and hence are suitable to resolve cattle rustling investigations.

  1. Investigating the Effect of Discussion Prompts on Knowledge Construction

    ERIC Educational Resources Information Center

    Howell, Ginger S.

    2014-01-01

    The purpose of this study was to examine the effect of Andrews' (1980) three structured divergent prompt designs (Playground prompt, Brainstorm prompt, and Focal prompt) on knowledge construction. Sixty-five online graduate participants at a university in a South Atlantic state were a part of the study. Students' posts were analyzed using the…

  2. Effective doses from cone beam CT investigation of the jaws

    PubMed Central

    Davies, J; Johnson, B; Drage, NA

    2012-01-01

    Objectives The purpose of the study was to calculate the effective dose delivered to the patient undergoing cone beam (CB) CT of the jaws and maxillofacial complex using the i-CAT Next Generation CBCT scanner (Imaging Sciences International, Hatfield, PA). Methods A RANDO® phantom (The Phantom Laboratory, Salem, NY) containing thermoluminence dosemeters were scanned 10 times for each of the 6 imaging protocols. Effective doses for each protocol were calculated using the 1990 and approved 2007 International Commission on Radiological Protection (ICRP) recommended tissue weighting factors (E1990, E2007). Results The effective dose for E1990 and E2007, respectively, were: full field of view (FOV) of the head, 47 μSv and 78 μSv; 13 cm scan of the jaws, 44 μSv and 77 μSv; 6 cm standard mandible, 35 μSv and 58 μSv; 6 cm high resolution mandible, 69 μSv and 113 μSv; 6 cm standard maxilla, 18 μSv and 32 μSv; and 6 cm high resolution maxilla, 35 μSv and 60 μSv. Conclusions Using the new generation of CBCT scanner, the effective dose is lower than the original generation machine for a similar FOV using the ICRP 2007 tissue weighting factors. PMID:22184626

  3. An investigation of the differential-outcomes effect within sessions

    PubMed Central

    Jones, B. Maxwell; White, K. Geoffrey

    1994-01-01

    The differential-outcomes effect is manifest as more accurate performance of a delayed conditional discrimination when alternative choice responses are followed by different reinforcers than when they are followed by the same reinforcer. In Experiment 1, a differential-outcomes effect was demonstrated within sessions by signaling the duration of food access for correct responses with stimuli appearing in conjunction with the sample stimuli. The delayed matching-to-sample performance of 5 pigeons was more accurate when green choice responses (matching a green sample) were followed by 3.5-s food access and red choice responses (matching a red sample) were followed by 0.5-s food access (different-outcome trials) than when the correct choice responses were both followed by 1.5-s reinforcers (same-outcome trials). In Experiment 2, the acquisition of this differential-outcomes effect was characterized by a progressive decrease in rate of forgetting on different-outcome trials and no change in rate of forgetting on same-outcome trials. In addition, accuracy at the shortest delay intervals for both different-outcome and same-outcome trials increased over acquisition, but to a greater extent for different-outcome trials. These data suggest that both memorial and attentional (time-dependent and time-independent) factors contribute to the differential-outcomes effect. PMID:16812728

  4. A New Chemotherapeutic Investigation: Piracetam Effects on Dyslexia.

    ERIC Educational Resources Information Center

    Chase, Christopher H.; Schmitt, R. Larry

    1984-01-01

    Compared to placebo controls, 28 individuals treated with Piracetam (a new drug thought to enhance learning and memory consolidation) showed statistically significant improvements above baseline scores on measures of effective reading accuracy and comprehension, reading speed, and writing accuracy. The medication was well tolerated and showed no…

  5. Investigation of Effective Strategies for Developing Creative Science Thinking

    ERIC Educational Resources Information Center

    Yang, Kuay-Keng; Lee, Ling; Hong, Zuway-R; Lin, Huann-shyang

    2016-01-01

    The purpose of this study was to explore the effectiveness of the creative inquiry-based science teaching on students' creative science thinking and science inquiry performance. A quasi-experimental design consisting one experimental group (N = 20) and one comparison group (N = 24) with pretest and post-test was conducted. The framework of the…

  6. The NMR investigation of the electromagnetic irradiation effects on bacteria

    NASA Astrophysics Data System (ADS)

    Drokina, T. V.; Lisin, V. V.; Popova, L. U.; Balandina, A. N.; Bitekhtina, M. A.

    2006-12-01

    The luminous marine bacteria (Photobacterium leiognathi, strain 54) are influenced by a nonthermal-intensity millimeter electromagnetic field, which was studied by nuclear magnetic resonance (NMR). It is shown that the proton spectrum of luminous bacteria depends on the electromagnetic irradiation effect (v = 42.2 GHz).

  7. Investigation of Fuel Additive Effects on Sooting Flames

    DTIC Science & Technology

    1989-07-28

    Ndubizu, C. C., and B. T. Zinn : Effects of Metallic Aditive Upon Soot Formation in Polymer Diffusion Flames. Combust, Flame 46, 301-314 (1982). 3.4...Plenum Press, New York, p. 143 (1981). 3.28 Wersborg, B. L., .1. B. Howard , and G. C. Williams: Physical Mechanisms in Carbon 3 Formation in Flames

  8. 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.

  9. 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…

  10. Investigating the Effectiveness of Group Work in Mathematics

    ERIC Educational Resources Information Center

    Sofroniou, Anastasia; Poutos, Konstantinos

    2016-01-01

    Group work permits students to develop a range of critical thinking, analytical and communication skills; effective team work; appreciation and respect for other views, techniques and problem-solving methods, all of which promote active learning and enhance student learning. This paper presents an evaluation of employing the didactic and…

  11. Investigation of Radiofrequency Radiation Effects on Excitable Tissues.

    DTIC Science & Technology

    1981-07-31

    Barnes, "Microwave Effects on Isolated Neurons Vary with Field Orientation," (abstract) Bioelectro - magnetics 1:205, 1980. 88 25. W. F. Pickard, Y. H...Barsoum, and F. J. Rosenbaum, "Is the Characean Plasmalemma a Radio-Frequency Rectifier?" (abstract), Bioelectro - magnetics 1:216, 1980. 26. W. F

  12. The effect of stuttering on communication: a preliminary investigation.

    PubMed

    Spencer, Elizabeth; Packman, Ann; Onslow, Mark; Ferguson, Alison

    2009-07-01

    This paper describes a study in which Systemic Functional Linguistics was applied to describe how people who stutter use language. The aim of the study was to determine and describe any differences in language use between a group of 10 adults who stutter and 10 matched normally-fluent speakers. In addition to formal linguistic analyses, analyses drawn from Systemic Functional Linguistics were used to further investigate the expression of both syntactic and semantic complexity. The findings from this study replicated previous findings of Packman et al. in which they found that the language used by people who stutter was significantly less complex than the control group. Another major finding was that adults who stuttered used the linguistic resource of modality significantly less than the normally-fluent matched peers. The implications these strategies have on communication and social participation will be discussed.

  13. Radiological investigation of the effects of red mud disaster.

    PubMed

    Kovács, T; Sas, Z; Somlai, J; Jobbágy, V; Szeiler, G

    2012-11-01

    On 4 October 2010, the gate of a red mud waste dump of a Hungarian alumina factory was damaged and ∼800.000 m(3) of alkaline red mud flooded the vicinity of the dumps. Red mud samples were collected from the contaminated area and they were investigated from the radiological point of view. The activity concentrations were as follows: (232)Th: 264 (194-337) Bq kg(-1), (238)U: 265 (197-332) Bq kg(-1), (226)Ra: 180 (143-237) Bq kg(-1), (40)K: 283 (228-360) Bq kg(-1). As a function of the moisture content (0-28 %), the obtained radon emanation coefficients were relatively high (7.6-20 %) and, consequently, the radon exhalation also increased.

  14. Organotypic tissue culture investigation of homocysteine thiolactone cardiotoxic effect.

    PubMed

    Lopatina, Ekaterina V; Kipenko, A V; Penniyaynen, V A; Pasatetskaya, N A; Djuric, D; Krylov, B V

    2015-06-01

    Homocysteine thiolactone was demonstrated to inhibit the growth of 10-12-day-old chicken embryo cardiac tissue explants at 7 × 10⁻⁹ -1 × 10⁻³ M concentrations in a dose-dependent manner. The maximal cardiotoxic effect of homocysteine thiolactone was detected at 1 × 10⁻³ M, which corresponds to severe hyperhomocysteinemia. The results of experiments on culturing of cardiac tissue explants in the medium containing homocysteine thiolactone (1 × 10⁻³ M) and ouabain at concentrations regulating the signal-transducing (1 × 10⁻¹⁰ M) and pumping (1 × 10⁻⁸ M) functions of Na⁺,K⁺ -ATPase indicate that the cardiotoxic effect of homocysteine thiolactone is supposed to result from inhibition of the Na⁺,K⁺ -ATPase pumping function.

  15. 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.

  16. 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.

  17. Investigation of irradiation effect on npn BJT electrical properties

    NASA Astrophysics Data System (ADS)

    Assaf, J.

    2016-10-01

    The irradiation effects of neutrons and gamma rays on a commercial type of npn Bipolar Junction Transistors (BJTs) are reported. The decrease of the current gain factor hFE for increasing dose was analyzed. Reduction ratio for hFE between 84% and 98% at the saturated reduction level have been obtained. This is due to a small decreasing in the collector current IC and a large increasing in the base current IB, where hFE=IC/IB. Reduction ratio per dose indicates the higher influence of the neutrons than that of gamma for the same equivalent dose. Moreover, the voltage gain as a function of the frequency decremented after irradiation, and the collector saturated voltage (VCEsat) was increased. These effects illustrate the damage in the function of BJTs.

  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. Investigation of certain diffraction effects in an optical disk.

    PubMed

    Yoo, J H; Lee, C W; Shin, D H; Bartlett, C; Cheong, K L; Erwin, J K; Mansuripur, M

    1997-12-10

    We report certain diffraction effects that are pertinent to the operation of double-layer optical recording media. For simulating cross-talk effects for double layers, the diffraction of light from the out-of-focus layer and the resulting distribution on the in-focus layer are studied by use of computer simulations. The findings are then verified qualitatively by direct measurements. We also describe a technique for analyzing (by computer simulation) the focus-error signal (FES), taking into account the cross talk between two layers, in systems that use the astigmatic method in conjunction with the double-layer disk. The results of our computer simulations of the FES give us a 10% cross-talk contribution to the original signal. The results of the FES evaluation are compared with those measured in an actual disk drive; good agreement between computation and measurement is obtained.

  20. 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

  1. 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

  2. The investigation of laparoscopic instrument movement control and learning effect.

    PubMed

    Lin, Chiuhsiang Joe; Chen, Hung-Jen

    2013-01-01

    Laparoscopic surgery avoids large incisions for intra-abdominal operations as required in conventional open surgery. Whereas the patient benefits from laparoscopic techniques, the surgeon encounters new difficulties that were not present during open surgery procedures. However, limited literature has been published in the essential movement characteristics such as magnification, amplitude, and angle. For this reason, the present study aims to investigate the essential movement characteristics of instrument manipulation via Fitts' task and to develop an instrument movement time predicting model. Ten right-handed subjects made discrete Fitts' pointing tasks using a laparoscopic trainer. The experimental results showed that there were significant differences between the three factors in movement time and in throughput. However, no significant differences were observed in the improvement rate for movement time and throughput between these three factors. As expected, the movement time was rather variable and affected markedly by direction to target. The conventional Fitts' law model was extended by incorporating a directional parameter into the model. The extended model was shown to better fit the data than the conventional model. These findings pointed to a design direction for the laparoscopic surgery training program, and the predictive model can be used to establish standards in the training procedure.

  3. Radiation Effects on Polypropylene Carbon Nanofibers Composites: Spectroscopic Investigations

    NASA Astrophysics Data System (ADS)

    Hamilton, John; Mion, Thomas; Cristian Chipara, Alin; Ibrahim, Elamin I.; Lozano, Karen; Tidrow, Steven; Magdalena Chipara, Dorina; Chipara, Mircea

    2010-03-01

    Dispersion of carbon nanostructures within polymeric matrices affects their physical and chemical properties (increased Young modulus, improved thermal stability, faster crystallization rates, higher equilibrium degree of crystallinity, modified glass, melting, and crystallization temperatures, enhanced thermal and electrical conductivity). Nevertheless, little is known about the radiation stability of such nanocomposites. The research is focused on spectroscopic investigations of radiation-induced modifications in isotactic polypropylene (iPP)-vapor grown nanofiber (VGCNF) composites. VGCNF were dispersed within iPP by extrusion at 180^oC. Composites containing various amounts of VGCNFs ranging from 0 to 20 % wt. were prepared and subjected to gamma irradiation, at room temperature, at various integral doses (10 MGy, 20 MGy, and 30 MGy). Raman spectroscopy, ATR, and WAXS were used to assess the radiation-induced modifications in these nanocomposites. Acknowledgements: This research was supported by the Welch Foundation (Department of Chemistry at UTPA), by Air Force Research Laboratory (FA8650-07-2-5061) and by US Army Research Laboratory/Office (W911NF-08-1-0353).

  4. 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.

  5. 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

  6. Postbuckling investigations of piezoelectric microdevices considering damage effects.

    PubMed

    Sun, Zhigang; Wang, Xianqiao

    2014-03-11

    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.

  7. Investigation on effective promotion of geothermal energy development

    NASA Astrophysics Data System (ADS)

    1991-03-01

    Efficient and effective measures for promoting geothermal energy development are studied considering the present status and the problems of the geothermal energy development in Japan. To promote it smoothly, solutions to technical and socioeconomic problems are needed: There are many unclear points about the location and amount of geothermal resources. For geothermal energy development, it is necessary to establish a consensus of procedures for surveying the development and settlement of selling prices, and risk sharing in the development. It is indispensable to consider an adjustment with natural parks and hot springs for the development. Troubles in making an adjustment are seen in many cases, and it is necessary to make efforts for that understanding. Improvement of economical efficiency of geothermal power generation is an important subject. From the above mentioned studies, the conclusion is obtained that it is most effective to make rules for development and to expand and strengthen resource prospecting by the government. If the rules are made, reduction of the development cost and shortening of the development period are planned, and the future of the geothermal energy business is expected to be promising.

  8. 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.

  9. 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.

  10. Parental Feeding and Child Eating: An Investigation of Reciprocal Effects.

    PubMed

    Steinsbekk, Silje; Belsky, Jay; Wichstrøm, Lars

    2016-09-01

    Parental feeding practices and children's eating behavior are consistently related to childhood obesity. However, it is not known whether parents' feeding practices predict obesogenic eating behavior or vice versa. In a Norwegian cohort (n = 797), it was found that greater parental use of food as a reward (instrumental feeding) when children were 6 predicted increased emotional overeating and food responsiveness, whereas greater parental encouragement to eat forecasted increased enjoyment of food 2 years later. No evidence of child effects emerged. Although children's eating behavior is relatively stable and established at an early age, findings suggest that parental feeding practices can serve as targets of intervention to prevent the development of obesogenic eating behavior.

  11. Solvent effects on cyanine derivatives: a PCM investigation.

    PubMed

    Jacquemin, Denis; Chibani, Siwar; Le Guennic, Boris; Mennucci, Benedetta

    2014-07-17

    In this work, we present time-dependent density functional theory calculations of the excited-state geometries and electronic properties of both model cyanines and BODIPY derivatives, which are particularly challenging dyes for theoretical chemistry. In particular, we focus on environmental effects, using a panel of approaches derived from the polarizable continuum model, including full corrected linear response (cLR) values determined through a very recently developed approach. It turns out that in idealized quasi-linear cyanines, all approaches provide very similar excited-state geometries though linear response (LR), and cLR models yield very different transition energies. For the fluoroborate derivatives, LR apparently overestimates the planarity of the excited-state geometries, and cLR optimizations yield slightly smaller fluorescence energies than LR, making these values closer to experimental references. The computed corrections are however too small to explain (taken alone) the significant theory/experiment discrepancies.

  12. 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.

  13. Ground effects of space weather investigated by the surface impedance

    NASA Astrophysics Data System (ADS)

    Pirjola, R.; Boteler, D.; Trichtchenko, L.

    2009-02-01

    The objective of this paper is to provide a discussion of the surface impedance applicable in connection with studies of geomagnetically induced currents (GIC) in technological systems. This viewpoint means that the surface impedance is regarded as a tool to determine the horizontal (geo)electric field at the Earth's surface, which is the key quantity for GIC. Thus the approach is different from the traditional magnetotelluric viewpoint. The definition of the surface impedance usually involves wavenumber-frequency-domain fields, so inverse Fourier transforming the expression of the electric field in terms of the surface impedance and the geomagnetic field results in convolution integrals in the time and space domains. The frequency-dependent surface impedance has a high-pass filter character whereas the corresponding transfer function between the electric field and the time derivative of the magnetic field is of a low-pass filter type. The relative change of the latter transfer function with frequency is usually smaller than that of the surface impedance, which indicates that the geoelectric field is closer to the time derivative than to the magnetic field itself. An investigation of the surface impedance defined by the space-domain electric and magnetic components indicates that the largest electric fields are not always achieved by the plane wave assumption, which is sometimes regarded as an extreme case for GIC. It is also concluded in this paper that it is often possible to apply the plane wave relation locally between the surface electric and magnetic fields. The absolute value of the surface impedance decreases with an increasing wavenumber although the maximum may also be at a non-zero value of the wavenumber. The imaginary part of the surface impedance usually much exceeds the real part.

  14. Effective field theory investigations of the XYZ puzzle

    NASA Astrophysics Data System (ADS)

    Segovia, Jorge

    2016-08-01

    Quantum Chromodynamics, the theory of strong interactions, predicts several types of bound states. Among them are conventional mesons (qq̅) and baryons (qqq), which have been the only states observed in experiments for years. However, in the last decade, many states that do not fit this picture have been observed at B-factories (BaBar, Belle and CLEO), at τ-charm facilities (CLEO-c, BESIII) and also at proton-proton colliders (CDF, D0, LHCb, ATLAS, CMS). There is growing evidence that at least some of the new charmonium- and bottomonium-like states, the so-called XYZ mesons, are new forms of matter such as quark-gluon hybrids, mesonic molecules or different arrangements of tetraquarks, pentaquarks... Effective Field Theories (EFTs) have been constructed for heavy-quark-antiquark bound states, but a general study of the XYZ mesons within the same framework has not yet been done. The scope of this conference proceedings is to discuss the possibilities we have in developing novel EFTs that, characterizing the conventional quarkonium states, facilitate also the systematic and model-independent description of the new exotic matter, in particular, the hybrid mesons.

  15. Investigation of geometric effect on the ultrasonic processing of liquids

    NASA Astrophysics Data System (ADS)

    Pasumarthi, Pavan

    Ultrasonic processing of liquids is used in many engineering fields, from sonochemistry to material processing. Acoustic cavitation and acoustic streaming are the two key phenomena responsible for the ultrasonic processing applications. Both of them are non-linear effects of ultrasonic wave propagation in liquids and are extremely hard to characterize either analytically or experimentally. This meant that there is limited knowledge about the interactions between the various parameters that affect the extent of the acoustic cavitation and streaming generated during the ultrasonic processing of liquids. In the current study, it was hypothesized that the geometric configuration of the ultrasonic processing equipment has an effect on the resultant acoustic pressure field, which in turn affects the acoustic cavitation and the acoustic streaming flow. Numerical modeling serves as a powerful tool to overcome the practical difficulties involved in experiments. Over the years, various finite element models have been developed to resolve the acoustic pressure field inside the ultrasonic processing cell. The majority of them have used a linear modeling of the Helmholtz equation with infinitely hard ultrasonic processing cell boundaries. In the current study, a non-linear numerical model was developed to resolve the acoustic pressure inside the ultrasonic processing cell. The viscous dissipation loss during the ultrasonic wave propagation is taken into account by replacing the general liquid material properties with complex material properties in the Helmholtz equation. The model developed was then validated with experimental results. An error analysis revealed that the simulation results show a mean error of about 33 %, with a maximum error of 78 % and a minimum error of 5 % in comparison with the experimental results. Following this, a method was introduced for the quantification of the acoustic cavitation zone size from the numerical modeling results of acoustic pressure

  16. The cloud effects phase of the laser induced lightning investigation

    NASA Astrophysics Data System (ADS)

    Moore, C. B.; Holden, D. N.; Griswold, J.

    1980-04-01

    A mountain-top laboratory facility has been established in central New Mexico for studies of the effects of high powered lasers on the ionization of the air and on the possible triggering of lightning from thunderclouds overhead. A net of electric field meters and another one with television cameras and video recorders have been established for determinations of the nature of normal and of triggered lightning in the operational area. A special electric field meter is carried beneath a captive balloon to heights of about 600 m above the facility and measured the electric fields there for the entire life of several storms. The field strengths aloft were as much as 6 fold greater than those observed at the surface; the field changes after lightning did not show the characteristic reversal caused by the corona produced space charge and the field after lightning recovered with a linear increase until lightning occurred again. Monitoring of electric fields aloft therefore provide a better choice of the optimum times for a lightning triggering attempt. As part of the 1979 field work, lightning discharges were induced twice by the use of wire-trailing, French rockets fired into thunderclouds over the Magdalena Mountains. As a result, interesting measurements of the breakdown process were obtained using AF Weapons Laboratory electromagnetic sensors: Magnetic field derivative signals in excess of 17 Teslas/second were observed in one of the triggered discharges.

  17. Geometrical investigations of the Casimir effect: Thickness and corrugation dependencies

    NASA Astrophysics Data System (ADS)

    Parashar, Prachi

    2011-12-01

    In the quantum theory the vacuum is not empty space. It is considered as a state of infinite energy arising due to zero point fluctuations of the vacuum. Calculation of any physically relevant process requires subtracting this infinite energy using a procedure called normalization. As such the vacuum energy is treated as an infinite constant. However, it has been established beyond doubt that mere subtraction of this infinite constant does not remove the effect of vacuum fluctuations and it cannot be treated just as a mathematical artifact. The presence of boundaries, which restricts the vacuum field, causes vacuum polarization. Any non-trivial space-time topology can cause similar effects. This is manifested as the Casimir effect, whereby the boundaries experience a force due to a change in the energy of the vacuum. To calculate the vacuum energy we treat the boundaries or other restrictive conditions as classical backgrounds, which impose boundary conditions on the solution of the vacuum field equations. Alternatively, we can incorporate the classical background in the Lagrangian of the system as classical potentials, which automatically include the boundary conditions in the field equations. Any change in the boundary conditions changes the vacuum energy and consequently the Casimir force is experienced by the boundaries. In this dissertation we study the geometric aspect of the Casimir effect. We consider both the scalar field and the physically relevant electromagnetic field. After a brief survey of the field in Chapter 1, we derive the energy expression using the Schwinger's quantum action principle in Chapter 2. We present the multiple scattering formalism for calculating the vacuum energy, which allows us to calculate the interaction energy between disjoint bodies and subtract out the divergent terms from the beginning. We then solve the Green's dyadic equation for the electromagnetic field interacting with the planar background surfaces, where we can

  18. Experimental investigation of gravity effects on sediment sorting on Mars

    NASA Astrophysics Data System (ADS)

    Kuhn, Nikolaus J.; Kuhn, Brigitte; Gartmann, Andres

    2014-05-01

    Sorting of sedimentary rocks is a proxy for the environmental conditions at the time of deposition, in particular the runoff that moved and deposited the material forming the rocks. Settling of sediment is strongly influenced by the gravity of a planetary body. As a consequence, sorting of a sedimentary rock varies with gravity for a given depth and velocity of surface runoff. Theoretical considerations for spheres indicate that sorting is more uniform on Mars than on Earth for runoff of identical depth. In reality, such considerations have to be applied with great caution because the shape of a particle strongly influences drag. Drag itself can only be calculated directly for an irregularly shaped particle with great computational effort, if at all. Therefore, even for terrestrial applications, sediment settling velocities are often determined directly, e.g. by measurements using settling tubes. In this study the results of settling tube tests conducted under reduced gravity during three experimental flights conducted in November 2012 and 2013 are presented. Nine types of sediment, ranging in size, shape and density were tested in custom-designed settling tubes during parabolas of Martian gravity lasting 20 to 25 seconds. Based on the observed settling velocities, the applicability of empirical relationships developed on Earth to assess particle settling on Mars are discussed. In addition, the potential effects of reduced gravity on the sorting of sedimentary rocks and their use as a proxy for runoff and thus environmental conditions on Mars are examined.

  19. Investigating the effective factors in creatinine changes among hemodialysis patients using the linear random effects model

    PubMed Central

    Shabankhani, B; Kazemnezhad, A; Zaeri, F

    2015-01-01

    Background and objectives:Out of 10 apparently healthy humans, one was somewhat suffering from one of the types of renal disease. Hemodialysis is known as the most applicable method of taking care of this group of patients. In addition, serum creatinine is an important mark in the performance of kidneys. The aim of the present study was to investigate the effective factors in creatinine and its effect on the performance of kidneys. Materials and methods: The present study is a longitudinal experiment in which 500 participants were randomly selected from the hemodialysis patients in Mazandaran Province. Creatinine variable was considered as the longitudinal responding variable, which was measured 3 times per year over a period of 6 years. The random effects model was also considered the most appropriate model for the collected data. Results:The total mean value of creatinine was 1.62 ± 0.49, among men 1.69 ± 0.46 and among women 35.1 ± 0.49. Variables of weight (p<0.001), age of disease diagnosis (p<0.001), time (p<0.001), gender (p<0.005), and cardiovascular diseases were significant and had effects on the trend of creatinine changes among the hemodialysis patients. Creatinine mean value had an increasing trend. Conclusion:Blood creatinine had a significant effect on the performance of kidneys, and the identification of variables that affected the creatinine level was highly helpful in controlling the performance of the kidneys. The results of most studies conducted on hemodialysis patients indicated that by measuring and controlling variables like weight, tobacco consumption, and control of related diseases like blood pressure could predict and control creatinine changes precisely. PMID:28255403

  20. Magnetite in Martian Meteorite Mil 03346 and Gusev Adirondack Class Basalt: Moessbauer Evidence for Variability in the Oxidation State of Adirondack Lavas

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    The Moessbauer spectrometers on the Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) have returned information on the oxidation state of iron, the mineralogical composition of Fe-bearing phases, and the distribution of Fe among oxidation states and phases [1,2,3]. To date, 100 and 85 surface targets have been analyzed by the Spirit and Opportunity spectrometers, respectively. Twelve component subspectra (8 doublets and 4 sextets) have been identified and most have been assigned to mineralogical compositions [4]. Two sextet subspectra result from the opaque and strongly magnetic mineral magnetite (Fe3O4 for the stoichiometric composition), one each for the crystallographic sites occupied by tetrahedrally-coordinated Fe3+ and by octahedrally-coordinated Fe3+ and Fe2+. At Gusev crater, the percentage of total Fe associated with magnetite for rocks ranges from 0 to 35% (Fig. 1) [3]. The range for soils (5 to 12% of total Fe from Mt, with one exception) is narrower. The ubiquitous presence of Mt in soil firmly establishes the phase as the strongly magnetic component in martian soil

  1. Characterization of carbonitrided and oxidized layers on low-carbon steel by conversion electron Moessbauer spectrometry, X-ray diffractometry, and X-ray photoelectron spectrometry

    SciTech Connect

    Kurosawa, K.; Li, H.L.; Ujihira, Y.; Nomura, K.

    1999-03-01

    The structures of low-carbon steel oxidized in an aqueous saline bath at 403 K and a fused salt bath at 673 K after carbonitriding were studied using conversion electron Moessbauer spectrometry (CEMS), x-ray diffractometry (XRD), and x-ray photoelectron spectrometry (XPS). Only a doublet peak caused by poor crystallinity of iron oxyhydroxides (FeOOH) or fine particles of iron oxides such as magnetite (Fe{sub 3}O{sub 4}) and maghemite ({gamma}-Fe{sub 2}O{sub 3}) was detected in the CEMS spectra of the surface of the carbonitrided steel oxidized in the aqueous saline bath. Corrosion resistance of the carbonitrided specimens was increased by oxidizing. The oxidized layers produced in the aqueous saline bath were superior to those produced in the fused salt bath as a result of pores in the carbonitrided zone being filled with finer particles of iron oxides and the production of tight, thick oxide layers of amorphous iron oxyhydroxides or fine iron oxides. Deformation of iron nitride ({gamma}{prime}-Fe{sub 4}N) crystals in the carbonitrided zone could not be detected by oxidizing in the aqueous saline bath but were detected in the fused salt bath at 673 K.

  2. 19 CFR 206.55 - Investigations to evaluate the effectiveness of relief.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Investigations to evaluate the effectiveness of relief. 206.55 Section 206.55 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION NONADJUDICATIVE INVESTIGATIONS INVESTIGATIONS RELATING TO GLOBAL AND BILATERAL SAFEGUARD ACTIONS, MARKET DISRUPTION,...

  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. 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.

  6. Wind-tunnel investigation of an externally blown flap STOL transport model including and investigation of wall effects

    NASA Technical Reports Server (NTRS)

    Gentry, G. L., Jr.

    1974-01-01

    A wind-tunnel investigation was conducted in the Langley V/STOL tunnel and in a scaled version of the Ames 40- by 80-foot tunnel test section installed as a liner in the Langley V/STOL tunnel to determine the effect of test-section size on aerodynamic characteristics of the model. The model investigated was a swept-wing, jet-powered, externally blown flap (EBF) STOL transport configuration with a leading-edge slat and triple-slotted flaps. The model was an 0.1645-scale model of a 11.58-meter (38.0-ft) span model designed for tests in a 40- by 80-foot tunnel. The data compare the aerodynamic characteristics of the model with and without the tunnel liner installed. Data are presented as a function of thrust coefficient over an angle-of-attack range of 0 deg to 25 deg. A thrust-coefficient range up to approximately 4.0 was simulated, most ot the tests being conducted at a free-stream dynamic pressure of 814 Newtons/sq m (17 lb sq ft). The data are presented with a minimum of analysis.

  7. 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…

  8. Investigating the Role of Collective Trust, Collective Efficacy, and Enabling School Structures on Overall School Effectiveness

    ERIC Educational Resources Information Center

    Gray, Julie

    2016-01-01

    This study investigated the role of collective trust, collective efficacy, and enabling school structures on overall school effectiveness. While the concept of organizational effectiveness can be complex and difficult to measure, the results of this research demonstrated a connection of these variables to school effectiveness. Collective trust had…

  9. The etiology and drug therapy of kinesia: investigations by means of the coriolis effect under cyclizine.

    PubMed

    Reicke, N

    1976-01-01

    The typical symptoms of kinesia were produced in 30 healthy test subjects by means of the Coriolis effect and the effect of cyclizine upon them was investigated in a single blind trial. The drug showed a clear effect on the autonomic symptoms (nausea) while there was no evidence of inhibition of the peripheral vestibular function.

  10. Disinfection effectiveness of organic chloramines, investigating the effect of pH.

    PubMed

    Amiri, Fariba; Mesquita, Maria M F; Andrews, Susan A

    2010-02-01

    The disinfection effectiveness of three organic N-chloramines (chlorinated amino acids and peptides) on the bacteria Escherichia coli (E. coli) was investigated, including a more detailed study into the pH dependency of the disinfection effectiveness of N-chloroglycine. The organic N-chloramines were prepared by combining sodium hypochlorite with each amino acid or peptide (glycine, Ala-Ala and Arg-Gly-Asp-Ser), at a N:Cl molar ratio of 1:0.4, and then used to treat E. coli suspensions for 180 min. No evidence of inactivation was observed at pH 8.1 for any of the tested organic N-chloramines. At pH 6.0 and 6.9, E. coli inactivation with N-chloroglycine was characterized by an initial lag phase, during which little or no measurable inactivation occurred, followed by a pseudo-first-order inactivation. This is in accordance with other results in the literature and supports the two step microbial inactivation mechanism proposed by some authors. Inactivation rate coefficients (Chick-Watson and lag coefficients) were calculated by fitting the experimental data with the Rennecker-Mariñas model. pH-dependent inactivation kinetics were observed, with faster inactivation rates occurring at lower pH values, when temperature and chlorine-to-nitrogen ratio where kept constant. N-chloroglycine was determined to be the only contributor to the inactivation process in these experiments. The free chlorine contribution was considered to be negligible in all experiments due to its very low concentration. As well, given that the anionic form of N-chloroglycine is expected to be the single predominant species over the tested pH range, changes in residual N-chloroglycine speciation could not be responsible for the observed pH-dependency of E. coli inactivation. However, while pH stress was considered as a possible synergistic factor, no significant effect of pH stress on E. coli viability was observed at the tested pH levels.

  11. 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…

  12. Investigation of the Effect of Blade Sweep on Rotor Vibratory Loads

    NASA Technical Reports Server (NTRS)

    Tarzanin, F. J., Jr.; Vlaminck, R. R.

    1983-01-01

    The effect of helicopter rotor blade planform sweep on rotor vibratory hub, blade, and control system loads has been analytically investigated. The importance of sweep angle, sweep initiation radius, flap bending stiffness and torsion bending stiffness is discussed. The mechanism by which sweep influences the vibratory hub loads is investigated.

  13. 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…

  14. 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.

  15. Experimental Investigation on the Effects of Chemical Heat Release in the Reacting Turbulent Plane Shear Layer.

    DTIC Science & Technology

    1981-01-01

    RD-Ai44 482 EXPERIMENTAL INVESTIGATION ON THE EFFECTS OF CHEMICAL 1/2 HEAT RELEASE IN THE..(U) CALIFORNIA INST OF TECH PASADENA A K WIALLACE JAN 81...TITLE (end Subtitle) S. TYPE OF REPORT 46 PERIOD COVERED Experimental Investigation on the Effects of Chemical Heat Release in the Reacting"Turbulent...Institute of Technology. 19. KEY 140ROS (Continue on reverse stdo of necesaray end identity by block number) Turbulence, combustion, shear layer, heat

  16. Freeze concentration effects on ice (photo) chemical kinetics investigated by UV-Vis spectroscopy

    NASA Astrophysics Data System (ADS)

    Newberg, J. T.; Arble, C.; Zhang, J.

    2013-12-01

    We will describe the setup of a fiber coupled UV-Vis spectrometer to investigate the chemistry and photochemistry of aqueous solutions before and after freezing. The photochemical degradation of pyranine at the isosbestic point was investigated. Direct photochemical degradation was minor compared to indirect degradation through hydroxyl radical (OH) attack at room temperature. At -10 C indirect OH degradation was increased relative to room temperature studies, and has been attributed to the freeze concentration effect. The reaction of bromate with bromide in the presence of acid to form molecular bromine was investigated. Upon freezing the formation rate of bromine significantly increases, which we attribute to the freeze concentration effect.

  17. An investigation into the effects of hydrogen on the fracture and deformation of Alloy X-750

    SciTech Connect

    Symons, Douglas M.

    1994-11-01

    this study investigated the effect of hydrogen on the fracture of a nickel-base superalloy, Alloy X-750 in the solution treated and aged (HTH) condition. The effect of hydrogen was examined through tensile testing and fracture toughness testing incorporating observations from scanning electron microscopy and light microscopy.

  18. 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…

  19. 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…

  20. 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…

  1. 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…

  2. Investigating the Effect of Origami Instruction on Preservice Teachers' Spatial Ability and Geometric Knowledge for Teaching

    ERIC Educational Resources Information Center

    Akayuure, Peter; Asiedu-Addo, S. K.; Alebna, Victor

    2016-01-01

    Whereas origami is said to have pedagogical benefits in geometry education, research is inclusive about its effect on spatial ability and geometric knowledge among preservice teachers. The study investigated the effect of origami instruction on these aspects using pretest posttest quasi-experiment design. The experimental group consisted of 52…

  3. 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…

  4. 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…

  5. 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…

  6. The Effect of Multipart Prompts on Children's Testimonies in Sexual Abuse Investigations

    ERIC Educational Resources Information Center

    Katz, Carmit; Hershkowitz, Irit

    2012-01-01

    Objective: The current study aimed to explore the frequency and effects of multipart prompts on the testimonies of children who were alleged victims of sexual abuse and were interviewed using the National Institute of Child Health and Human Development (NICHD) Investigative Protocol. The effects of the multipart prompts were studied by considering…

  7. A Developmental Investigation of Other-Race Contact and the Own-Race Face Effect

    ERIC Educational Resources Information Center

    Walker, Pamela M.; Hewstone, Miles

    2006-01-01

    Research over the past two decades has demonstrated that individuals are better at recognizing and discriminating faces of their own race versus other races. The own-race effect has typically been investigated in relation to recognition memory; however, some evidence supports an own-race effect at the level of perceptual encoding in adults. The…

  8. Assessment of the optimum degree of Sr{sub 3}Fe{sub 2}MoO{sub 9} electron-doping through oxygen removal: An X-ray powder diffraction and {sup 57}Fe Moessbauer spectroscopy study

    SciTech Connect

    Lopez, Carlos A.; Viola, Maria del C.; Pedregosa, Jose C.; Mercader, Roberto C.

    2010-10-15

    We describe the preparation and structural characterization by X-ray powder diffraction (XRPD) and Moessbauer spectroscopy of three electron-doped perovskites Sr{sub 3}Fe{sub 2}MoO{sub 9-{delta}} with Fe/Mo = 2 obtained from Sr{sub 3}Fe{sub 2}MoO{sub 9}. The compounds were synthesized by topotactic reduction with H{sub 2}/N{sub 2} (5/95) at 600, 700 and 800 {sup o}C. Above 800 {sup o}C the Fe/Mo ratio changes from Fe/Mo = 2-1 < Fe/Mo < 2. The structural refinements of the XRPD data for the reduced perovskites were carried out by the Rietveld profile analysis method. The crystal structure of these phases is cubic, space group Fm3-bar m, with cationic disorder at the two different B sites that can be populated in variable proportions by the Fe atoms. The Moessbauer spectra allowed determining the evolution of the different species formed after the treatments at different temperatures and confirm that Fe ions in the samples reduced at 600, 700 and 800 {sup o}C are only in the high-spin Fe{sup 3+} electronic state.

  9. Numerical Investigation of Thermal and Thermo-mechanical Effective Properties for Short Fibre Reinforced Composite

    NASA Astrophysics Data System (ADS)

    Ioannou, Ioannis; Hodzic, Alma; Gitman, Inna M.

    2016-12-01

    This study aims to investigate the thermal conductivity and the linear coefficient of thermal expansion for short fibre reinforced composites. The study combines numerical and statistical analyses in order to primarily examine the representative size and the effective properties of the volume element. Effects of various micromechanical parameters, such as fibre's aspect ratio and fibre's orientation, on the minimum representative size are discussed. The numerically acquired effective properties, obtained for the representative size, are presented and compared with analytical models.

  10. Effective use of forensic science in volume crime investigations: identifying recurring themes in the literature.

    PubMed

    Ludwig, Anika; Fraser, Jim

    2014-01-01

    New scientific, technological and legal developments, particularly the introduction of national databases for DNA and fingerprints, have led to increased use of forensic science in the investigation of crime. There is an assumption, and in some instances specific assertions, that such developments bring improvements either in broad criminal justice terms or more narrowly in terms of economic or practical efficiencies. The underlying presumption is that the new technological opportunities will be understood and effectively implemented. This research investigates whether such increases in activity have also been accompanied by improvements in the effective use of forensic science. A systematic review of thirty-six reports published (predominantly in England and Wales) since the 1980s, which have considered the use of forensic science in the investigation of volume crimes, was carried out. These reports have identified a number of recurrent themes that influenced how effectively forensic science was used in investigations. The themes identified included forensic knowledge and training of investigators, communication and information exchange between specialists and investigators, timeliness of forensic results, interagency relationships and deployment of crime scene examiner resources. The research findings suggest that these factors continue to hinder the effective use of forensic science despite technological advances and this paper considers their potential causes.

  11. Investigations into the specific effects of rosemary oil at the receptor level.

    PubMed

    Sagorchev, P; Lukanov, J; Beer, A M

    2010-07-01

    Rosemary oil is used frequently in phytotherapy. The objective of the present study was to investigate the extent to which rosemary oil shows other effects on the smooth muscles than the familiar spasmolytic effects. The effects of rosemary oil on the spontaneous contractile activity were investigated in in vitro experiments with circular smooth-muscle strips of the guinea pig stomach. Rosemary oil was found to have agonistic effects on the alpha(1) and alpha(2) adrenergic receptors. These effects can be registered at concentrations up to 25 microl/l of rosemary oil. At higher concentrations the spasmolytic effect described in other reports could be detected. At concentrations above 100 microl/l rosemary oil, the effect of 10(-5)M ACH is completely suppressed. The results permit the assumption that, besides the spasmolytic effects investigated to date, owing to its specific effects on the alpha(2) adrenergic receptors of the nerve cells, rosemary oil brings about an additional improvement of local blood circulation and alleviates pain.

  12. 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.

  13. An Exploratory Investigation of Jet Blast Effects on a Dust Covered Surface at Low Ambient Pressure

    NASA Technical Reports Server (NTRS)

    1961-01-01

    An Exploratory Investigation of Jet Blast Effects on a Dust Covered Surface at Low Ambient Pressure. A preliminary investigation has been conducted to determine the effects of jet blast, at low ambient pressures, on a surface covered with loose particles. Tests were conducted on configurations having from one to four nozzles at 0, 10, 20, and 30 degree cant angles and heights of 2 and 4 inches above the particle-covered surface. [Entire movie available on DVD from CASI as Doc ID 20070030966. Contact help@sti.nasa.gov

  14. 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.

  15. Moessbauer/XRF MIMOS Instrumentation and Operation During the 2012 Analog Field Test on Mauna Kea Volcano, Hawaii

    NASA Technical Reports Server (NTRS)

    Graff, Trevor G.; Morris, R. V.; Klingelhofer, G.; Blumers, M.

    2013-01-01

    Field testing and scientific investigations were conducted on the Mauna Kea Volcano, Hawaii, as part of the 2012 Moon and Mars Analog Mission Activities (MMAMA). Measurements were conducted using both stand-alone and rover-mounted instruments to determine the geophysical and geochemical properties of the field site, as well as provide operational constraints and science considerations for future robotic and human missions [1]. Reported here are the results from the two MIMOS instruments deployed as part of this planetary analog field test.

  16. 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.

  17. Using a Cell Phone to Investigate the Skin Depth Effect in Salt Water

    NASA Astrophysics Data System (ADS)

    Rayner, John

    2017-02-01

    This paper describes an experimental investigation of the skin depth effect for electromagnetic waves in salt water using a cell phone that is immersed to a critical depth where it no longer responds when called. We show that this critical depth is directly proportional to the theoretical skin depth for a range of salt concentrations.

  18. 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…

  19. Investigation of the Effects of Brain Teasers on Attention Spans of Pre-School Children

    ERIC Educational Resources Information Center

    Altun, Meryem; Hazar, Muhsin; Hazar, Zekihan

    2016-01-01

    The purpose of this study is to investigate the effects of brain teasers on attention spans of preschool children of age six. The study was conducted using an experimental design with a control group and pre-test/post-test. The sample of the study is children of age six selected via random appointment among ones who were enrolled in the Merkez…

  20. 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…

  1. 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.

  2. 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…

  3. 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…

  4. Investigating the Comparative Effectiveness of Fluency Building Techniques during Peer Tutoring

    ERIC Educational Resources Information Center

    Olson, Peter C.

    2013-01-01

    Acting as a tutor can increase a student's academic skills. The purpose of this study was to investigate the relative effectiveness of two types of reading fluency building strategies--echo reading and error correction--for the fluency improvement of tutors. Forty lower performing readers were trained in echo reading and error correction. Then,…

  5. A Naturalistic Investigation of Media Multitasking While Studying and the Effects on Exam Performance

    ERIC Educational Resources Information Center

    Patterson, Michael C.

    2017-01-01

    The present study investigated the use of multiple digital media technologies, including social networking platforms, by students while preparing for an examination (media multitasking) and the subsequent effects on exam performance. The level of media multitasking (number of simultaneous media technologies) and duration of study were used as…

  6. 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,…

  7. 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…

  8. 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…

  9. 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…

  10. Investigating the Effectiveness of Teaching Methods Based on a Four-Step Constructivist Strategy

    ERIC Educational Resources Information Center

    Calik, Muammer; Ayas, Alipasa; Coll, Richard K.

    2010-01-01

    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…

  11. The Investigation of the Effects of Authentic Assessment Approach on Prospective Teachers' Problem-Solving Skills

    ERIC Educational Resources Information Center

    Kinay, Ismail; Bagçeci, Birsen

    2016-01-01

    The purpose of this study was to investigate the effect of authentic assessment, an approach used in Scientific Research Methods, on problem solving skills of prospective classroom teachers. The participant groups of the study consisted of sophomore prospective teachers who study at Dicle University in the Ziya Gökalp Education Faculty Classroom…

  12. 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…

  13. 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.

  14. 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…

  15. 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 graders)…

  16. 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…

  17. 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…

  18. 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…

  19. Investigating Aerobic, Anaerobic Combine Technical Trainings' Effects on Performance in Tennis Players

    ERIC Educational Resources Information Center

    Suna, Gürhan; Kumartasli, Mehmet

    2017-01-01

    The aim of this study is to investigate eight-week aerobic, anaerobic combine technical trainings' effects on developments of performance. 21 athletes of tennis proficiency students from Sports Sciences Department were joined to the study voluntarily. Participated in the research athletes' ages' mean was 22,2 ± 0,3 year, lengths' mean was 177,3 ±…

  20. 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.…

  1. 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 underwent…

  2. The Effect of Lake Erie on Climate, Student Guide and Teacher Guide. OEAGLS Investigation 2.

    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 study the effects of air temperature on air density and movement, the circulation of air and how it changes the amount of precipitation in the area around the Great Lakes, and the implications of the "lake…

  3. 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…

  4. Investigating the Effect of Using Self-Assessment on Iranian EFL Learners' Writing

    ERIC Educational Resources Information Center

    Heidarian, Nakisa

    2016-01-01

    This study investigated the effect of using self-assessment on Iranian EFL learners' writing. The purpose of this study was to demonstrate whether using of self-assessment as an assessment method was influential in developing learners' English writing performance generally writing processes specifically. The participants of this study consisted of…

  5. 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…

  6. An Investigation of the Effectiveness of Three Methods of Teaching Reading Vocabulary.

    ERIC Educational Resources Information Center

    Hare, Sally Zalkin

    The purpose of this investigation was to compare the effectiveness of three methods of teaching reading vocabulary to third-grade students. Eighty third-grade students were given Form 1 of the Gates-MacGinitie Reading Tests, Vocabulary Section, Primary C, as a pretest and randomly assigned to three experimental groups and a control group. Forty…

  7. Investigating Effect of Origami-Based Instruction on Elementary Students' Spatial Skills and Perceptions

    ERIC Educational Resources Information Center

    Cakmak, Sedanur; Isiksal, Mine; Koc, Yusuf

    2014-01-01

    The authors' purpose was to investigate the effect of origami-based instruction on elementary students' spatial ability. The students' self-reported perceptions related to the origami-based instruction were also examined. Data was collected via purposive sampling techniques from students enrolled in a private elementary school. A spatial ability…

  8. Moessbauer studies in zinc-manganese ferrites for use in measuring small velocities and accelerations with great precision

    NASA Technical Reports Server (NTRS)

    Escue, W. T.; Gupta, R. G.; Mendiratta, R. G.

    1975-01-01

    Mossbauer spectroscopy was used for a systematic study of the magnetic behavior of manganese and zinc in mixed ferrites. It was observed that Zn2+ has preference to substitute Mn2+ at interstitial sites where the metal ions are tetrahedrally coordinated with four oxygen neighbors. The internal magnetic hyperfine field at the tetrahedral iron site is larger than that at the octahedral site. The relaxation effects were observed to play an important role as the zinc contents were increased, while the spin-correlation time and the magnetic field were observed to decrease in strength. It is concluded that Mossbauer effect data on complex materials, when used in conjunction with other data, can provide useful insight into the origin of the microscopic properties of magnetic materials.

  9. 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.

  10. Investigations of the precedence effect in budgerigars: Effects of stimulus type, intensity, duration, and location

    NASA Astrophysics Data System (ADS)

    Dent, Micheal L.; Dooling, Robert J.

    2003-04-01

    Auditory experiments on the localization of sounds in the presence of reflections, or echoes, that arrive later and from different directions are important to understanding hearing in natural environments. The perceived location of the auditory image can change with the time delay between the presentations of a leading and lagging sound. These changes in perceived location, encompassing the precedence effect, have been examined behaviorally or physiologically in humans and a number of animals. Here, these results are extended to include budgerigars. Behavioral methods were used to measure the discrimination performance between a stimulus presented at + and -90° azimuth with a delay (left-), from the same two stimuli presented with the opposite delay (right-left). At short delays, where humans experience summing localization, budgerigars have difficulty discriminating between the two presentation types. With increasing delays, where humans experience localization dominance, budgerigars show improved discrimination performance. At even longer delays, where echo thresholds are found in humans, discrimination performance worsens again. The shapes of the discrimination functions are affected by the intensity, locations, and durations of the stimuli, and are subject to a buildup effect. These results show that budgerigars exhibit the phases of the precedence effect similar to humans and other animals.

  11. 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

    2017-02-01

    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.

  12. 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.

  13. 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.

  14. Experimental investigation of line-tying effects on the spheromak tilt mode

    SciTech Connect

    Wysocki, F.J.

    1986-02-01

    A variety of passive stabilization techniques compatible with S-1 inductive spheromak formation has been evaluated for effectiveness against the MHD tilting instability. A line-tying stabilization effect has been previously identified theoretically. In the present work, the effects have been experimentally identified and investigated. The perturbed current patterns within passive stabilizing structures have been measured, and line-tying currents have been identified. The simple ring model of tilting has been expanded to include line-tying, and has provided estimates for growth rates which agree well with the measured values. 51 refs., 18 figs., 1 tab.

  15. 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.

  16. 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.

  17. 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

  18. [Investigation of enhancing effect for hydride generation-atomic fluorescence of transition metal elements].

    PubMed

    Sun, Han-Wen; Suo, Ran

    2008-11-01

    A mechanism of hydride generation based on disassembly reaction of hydrogen-transferred interim state [M(BH4)m]* was developed by investigating the effect of reaction medium acidity on hydride generation. The effects of Co2+ and Ni2+, phenanthroline and 8-hydroxyquinoline on hydride generation-atomic fluorescence signals of Zn, Cd, Cu and Ni were studied, respectively, and their enhancing mechnism was discussed. The enhancing effect Co2+ and Ni2+ on the fluorescence signals of Zn and Cd was due to the increase in transmission efficiency of hydride of Zn and Cd. There was a synergic enhancing effect between phenanthroline or 8-hydroxyquinoline and Co2+ on the fluorescence signals of Zn and Cd, however no synergic enhancing effect between phenanthroline and 8-hydroxyquinoline on the fluorescence signals of Zn and Cd. The simulative action of cationic surfactant, anion surfactant and non-ionic surfactant surfactant to hydride generation was investigated. It is shown that both cationic surfactant and non-ionic surfactant have obvious enhancing effect on the fluorescence signals of analytes because of the decrease in surface tension of reaction solution. The release characteristics of hydride from the absorption solution containing surfactant was ulteriorly examined by using graphite furnace atomic absorption spectrometry, and the mechanism of enhancing effect of surfactant on hydride generation and transmission was proposed.

  19. Theoretical Investigation on Skin Effect Factor of Conductor in Power Cables

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Kanaoka, Mamoru

    This paper describes a newly-derived theoretical equation on the skin effect factor of power cables, and its application to large-size OF and XLPE cables with segmental conductors, including insulated wires. The skin effect factors calculated with the new equation were fit very well to measurements in wide range conductor sizes. In the new equation, the important factor which characterizes the skin effect of segmental conductors is the `equivalent conductivity ratio' ν defined by the ratio of longitudinal conductivity in axial direction of conductor to conductivity of conductor wires. Since the obtained ratio ν in XLPE cable was three times greater than that in OF cable, the larger longitudinal eddy current passing from a wire to another increased the eddy current loss in conductor, which increased the conductor loss of XLPE cable. The new equation enables us to investigate quantitatively the dominant loss component affecting the skin effect factor. Then, the skin effect factors and coefficients for OF and XLPE cables were investigated with the new equation. It was revealed that the best number of separation, in which the skin effect became minimum, existed in OF and XLPE cables with segmental conductors. In addition, it was confirmed that the skin effect coefficients ks1 calculated with the new equation were consistent well with those used in JCS.

  20. Experimental investigation of the effect of an oscillating airstream (Katzmayr effect) on the characteristics of airfoils

    NASA Technical Reports Server (NTRS)

    TOUSSAINT; KERNEIS; GIRAULT

    1924-01-01

    A series of experiments were conducted related to the action of an airstream oscillating vertically on supporting surfaces. The object of the experiments was to verify the very interesting results of Mr. Katzmayr, Director of the Vienna Aerodynamics Laboratory, and, if possible, to obtain more complete data on the effect of the amplitude and velocity of the oscillations of the airstream. The results obtained by Mr. Katzmayr are briefly summarized. The conduct of the numerous experiments to verify his results are described in detail. Experimental results are given in tabular and graphical form.

  1. Investigation of flow characteristics effects on heat transfer in water-cooled cylinder heads

    NASA Astrophysics Data System (ADS)

    Hassan, M. A. M.; Abd El-Hameed, H. M.; Mahmoud, Osama E.

    2016-08-01

    An experimental and theoretical study has been performed to investigate the effect of flow characteristics on heat-transfer in water impingement-cooled cylinder heads. Numerous investigations have been made using a three-dimensional model, which is designed and solved by FLUENT software using both realizable k-ɛ turbulent and heat transfer models. The simulation investigates a fully developed turbulent-water flow in asymmetric heated circular passage cooled by parallel flow or impingement of circular submerged confined liquid jet. The following parameters were investigated for both parallel flow and jet impingement flow: flow velocities (1, 2 and 3 m/s), bulk fluid temperatures (50, 70 and 90 °C), main duct diameters (6, 8, 10 and 12 mm). While the following parameters were investigated for jet impingement flow, jet diameter ratio (0.6, 0.8 and 1) and jet inclination angles as measured from horizontal (45°, 60° and 90°). Experimental results were used to verify the theoretical model. Results indicate that, the normal jet (90°) gives the maximum cooling effect in comparison to other angles while the maximum heat transfer coefficient is found at jet interface position.

  2. 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.

  3. 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.

  4. Investigation of the effectiveness of smoke suppressant fuel additives for turbojet applications. Master's thesis

    SciTech Connect

    Bramer, J.R.

    1982-10-01

    Seven fuel additives were tested to investigate their effectiveness at reducing exhaust stack gas opacity in a turbojet test cell. Exhaust particle sizes and mass concentrations were determined at the engine and stack exhausts using measurements of light transmittance at three frequencies. Particle samples were also collected at the engine exhaust and measured with a scanning electron microscope to verify the optical technique. Nitrous oxide emissions were measured at the test cell stack exhaust. Four of the additives tested were found effective at reducing stack exhaust opacity and particulate mass concentration. None of the additives had any measurable effect on particle diameters. No meaningful changes in particle size or mass occurred between the engine and stack exhausts. The optical technique for determining particle size was verified effective using the scanning electron microscope. No additive had any significant effect on nitrous oxide production.

  5. Differential Gene Expression to Investigate the Effects of Low-level Electrochemical Currents on Bacillus subtilis

    PubMed Central

    2011-01-01

    With the emergence and spread of multidrug resistant bacteria, effective methods to eliminate both planktonic bacteria and those embedded in surface-attached biofilms are needed. Electric currents at μA-mA/cm2 range are known to reduce the viability of bacteria. However, the mechanism of such effects is still not well understood. In this study, Bacillus subtilis was used as the model Gram-positive species to systematically investigate the effects of electrochemical currents on bacteria including the morphology, viability, and gene expression of planktonic cells, and viability of biofilm cells. The data suggest that weak electrochemical currents can effectively eliminate B. subtilis both as planktonic cells and in biofilms. DNA microarray results indicate that the genes associated with oxidative stress response, nutrient starvation, and membrane functions were induced by electrochemical currents. These findings suggest that ions and oxidative species generated by electrochemical reactions might be important for the killing effects of these currents. PMID:22078549

  6. Investigation of the off-diagonal Seebeck effect and Peltier effect on textured YBa 2Cu 3O 7-δ

    NASA Astrophysics Data System (ADS)

    He, Z. H.; Zhong, F. Q.; Luo, Y. Y.; Wu, M.; Gavalek, W.; Liang, K. F.; Fung, P. C. W.

    1997-08-01

    Both of the off-diagonal Seebeck effect and the off-diagonal Peltier effect were investigated with the use of the same textured sample YBa 2Cu 3O 7-δ (Y-123) and the same experimental setup. The reliability of the measurement is studied by applying different heat-conductive mediums. The flatness of both of the sample and the heat-conducting block, and the matching between them are found very important for the reduction of the heat resistance. The annealing effect on the Sxz is also studied and found in accordance with that studied by the thermoelectric power.

  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. Investigation of the effects of magnetic field exposure on human melatonin. Interim report

    SciTech Connect

    Graham, C.; Cook, M.R.; Cohen, H.D.

    1994-08-01

    Several rodent studies have suggested that magnetic field exposure may alter the daily pattern of melatonin secretion. This study investigated melatonin levels in mean exposed overnight to magnetic fields of 10 mG and 200 mG. The study also assessed the potential effects of exposure on a number of performance and self-reported endpoints in the subjects. Investigation of this area is important, as altered diurnal melatonin cycles have been linked to a variety of endpoints, including reproductive outcome, neurobehavioral function, and carcinogenesis. The results of this investigation did not support the a priori hypothesis that exposure to 60-Hz magnetic fields of 10 mG and 200 mG alters nighttime melatonin levels in a population of adult males. However, the data suggested the possibility of differential sensitivity to magnetic fields based on an individual`s baseline melatonin level.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Ishida, Tateki

    2015-01-01

    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][PF6]), 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.

  19. Investigation of magnetic proximity effect in Ta/YIG bilayer Hall bar structure

    SciTech Connect

    Yang, Yumeng; Wu, Baolei; Wu, Yihong; Yao, Kui; Shannigrahi, Santiranjan; Zong, Baoyu

    2014-05-07

    In this work, the investigation of magnetic proximity effect was extended to Ta which has been reported to have a negative spin Hall angle. Magnetoresistance (MR) and Hall measurements for in-plane and out-of-plane applied magnetic field sweeps were carried out at room temperature. The size of the MR ratio observed (∼10{sup −5}) and its magnetization direction dependence are similar to that reported in Pt/yttrium iron garnet, both of which can be explained by the spin Hall magnetoresistance theory. Additionally, a flip of magnetoresistance polarity is observed at 4 K in the temperature dependent measurements, which can be explained by the magnetic proximity effect induced anisotropic magnetoresistance at low temperature. Our findings suggest that both magnetic proximity effect and spin Hall magnetoresistance have contribution to the recently observed unconventional magnetoresistance effect.

  20. 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.

  1. Investigation of acute effects of graphene oxide on wastewater microbial community: a case study.

    PubMed

    Ahmed, Farid; Rodrigues, Debora F

    2013-07-15

    The market for graphene-based products, such as graphene oxide (GO), is projected to reach nearly $675 million by 2020, hence it is expected that large quantities of graphene-based wastes will be generated by then. Wastewater treatment plants will be one of the ultimate repositories for these wastes. Efficient waste treatment relies heavily on the functions of diverse microbial communities. Therefore, systematic investigation of any potential toxic effects of GO in wastewater microbial communities is essential to determine the potential adverse effects and the fate of these nanomaterials in the environment. In the present study, we investigate the acute toxicity, i.e. short-term and high load, effect of GO on the microbial functions related to the biological wastewater treatment process. The results showed that toxic effects of GO on microbial communities were dose dependent, especially in concentrations between 50 and 300mg/L. Bacterial metabolic activity, bacterial viability, and biological removal of nutrients, such as organics, nitrogen and phosphorus, were significantly impacted by the presence of GO in the activated sludge. Furthermore, the presence of GO deteriorated the final effluent quality by increasing the water turbidity and reducing the sludge dewaterability. Microscopic techniques confirmed penetration and accumulation of GO inside the activated sludge floc matrix. Results demonstrated that the interaction of GO with wastewater produced significant amount of reactive oxygen species (ROS), which could be one of the responsible mechanisms for the toxic effect of GO.

  2. 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.

  3. Investigation of the Effects of Teaching Core Exerciseson Young Soccer Players

    ERIC Educational Resources Information Center

    Yapici, Aysegül

    2016-01-01

    The objective of this study is to investigate the effects of teaching core exercises on some motoric parameters in young soccer players. 32 amateur male football players from Afjet Afyonspor and Muglaspor football team; 16 experimental group (average age 13.75 ± 0.46 years; mean body height 1.65.± 0.09 cm; mean body mass 52.88 ± 8.04 kg) and 16…

  4. 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

  5. Reduced Humidity Effects on Probe Nano-Oxidation Investigated Using Dynamic Force Microscope

    NASA Astrophysics Data System (ADS)

    Kuramochi, Hiromi; Ando, Kazunori; Tokizaki, Takashi; Yokoyama, Hiroshi

    2006-03-01

    Humidity effects on nano-oxidation are investigated using a dynamic force microscope in the humidity range of 30-60%. Oxide size and detected faradaic current increased with relative humidity and applied voltage. The aspect ratios of fabricated oxides at various humidities are approximately of the same magnitude. Scanning probe microscope nano-oxidation in the dynamic mode is less subject to the relative humidity than that in the contact mode.

  6. Experimental Investigation of a Supersonic Boundary Layer Including Favorable Pressure Gradient Effects

    DTIC Science & Technology

    2011-07-21

    United States Government. EXPERIMENTAL INVESTIGATION OF A SUPERSONIC BOUNDARY LAYER INCLUDING FAVORABLE PRESSURE GRADIENT EFFECTS THESIS Presented to...flow to be disturbed from its original state . Aside from providing a non-intrusive method of measurement, LDV has the advantage of measuring the...providing some useful test of turbulence modeling. 4. Well-defined experimental boundary conditions: All incoming conditions (especially the state of

  7. Investigating How Contact Angle Effects the Interaction between Water and a Hydrophobic Surface

    NASA Astrophysics Data System (ADS)

    Poynor, Adele; Neidig, Caitlyn

    2012-02-01

    By definition hydrophobic substances hate water. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low-density region forms near the surface. Contact angle is a measure of how hydrophobic a surface is. We have employed an automated home-built Surface Plasmon Resonance (SPR) apparatus to investigate the effect of varying the contact angle on the depletion layer

  8. An Experimental Investigation of Some Three-Dimensional Effects of Stationary Circular Cylinders

    NASA Astrophysics Data System (ADS)

    Weiss, Lesley G.; Szewczyk, Albin A.

    1999-11-01

    Some effects of three-dimensionality on the near wake of a circular cylinder were investigated in the subcritical Reynolds number range. The three-dimensional effects were imposed by a linear shear approach flow and taper in the cylinder. A rake of 16 hot-wires was placed in the near wake in order to investigate the effects of three-dimensionality on the vortex shedding along the span. Results of the present investigation indicate that the three-dimensionality triggers the formation of constant frequency cells. The number and size of the cells are dependent on the combination of nonuniformity in the flow and cylinder. When based on midspan values of diameter and velocity the Strouhal number remains constant within each cell and is centered around the two-dimensional Strouhal number. If the Strouhal number is based on local values it tends to vary linearly within each cell and jump between cell boundaries. A pseudo-visualization technique using time series data is used to show the splitting of vortex cells of different frequency.

  9. 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.

  10. Investigating the effect of some parameters of the channel on the characteristics of tunneling carbon nanotube field-effect transistor

    NASA Astrophysics Data System (ADS)

    Valed Karimi, Najmeh; Pourasad, Yaghoub

    2016-08-01

    This paper studies p-i-n tunneling carbon nanotube field-effect transistor to investigate the effect of various parameters of the channel on the characteristics of tunneling carbon nanotube field-effect transistor. Tunneling carbon nanotube field-effect transistor (T-CNTFET) has been simulated using non-equilibrium Green's function (NEGF), and the transmission was conducted through inelastic scattering. Besides the evaluation of device performance, various parameters of the channel were also compared. One of the parameters is considered as the variable, while other parameters of the channel are constant. Then, improved characteristics were discussed by selection of some channel parameters. T-CNTFET with CNT (10, 0) with oxide thickness = 1 nm shows reduced sub-threshold swing (18 mV/decade).

  11. Investigation of the Influence of Tool Geometry on Effective Strain Distribution in Full Forward Extrusion

    NASA Astrophysics Data System (ADS)

    Merklein, Marion; Ndzomssi, Franck; Engel, Ulf

    2011-05-01

    Due to strain hardening of the material, the hardness of cold forged parts is considerably improved. It is well known that the hardness of cold forged parts is closely related to its deformation, and that this relation is not dependent on the deformation process. The effective strain defines the local deformation, and can be determined in simulation of the cold forming process. In order to reach the required or to set specific hardness distribution with cold forging without any heat treatment processes, it is necessary to find out which manufacturing parameters influence the effective strain, and determine the effects of these parameters. The research work covered in this paper investigates the influence of the die geometry (as manufacturing parameter) on the effective strain. For that, a full forward extrusion process was modeled using the FE-software Simufact. Forming and three parameters of the die geometry, namely the deformation ratio, the shoulder radius and the opening angle were varied. The maximum effective strain from each combination is determined, and the effects of each considered parameter as well as the effects of interactions between these factors are checked.

  12. Investigating the nature and time-course of the modality shift effect between vision and touch.

    PubMed

    Miles, Eleanor; Brown, Richard; Poliakoff, Ellen

    2011-05-01

    It is well known that stimuli grab attention to their location, but do they also grab attention to their sensory modality? The modality shift effect (MSE), the observation that responding to a stimulus leads to reaction time benefits for subsequent stimuli in the same modality, suggests that this may be the case. If noninformative cue stimuli, which do not require a response, also lead to benefits for their modality, this would suggest that the effect is automatic. We investigated the time-course of the visuotactile MSE and the difference between the effects of cues and targets. In Experiment 1, when visual and tactile tasks and stimulus locations were matched, uninformative cues did not lead to reaction time benefits for targets in the same modality. However, the modality of the previous target led to a significant MSE. Only stimuli that require a response, therefore, appear to lead to reaction time benefits for their modality. In Experiment 2, increasing attention to the cue stimuli attenuated the effect of the previous target, but the cues still did not lead to a MSE. In Experiment 3, a MSE was demonstrated between successive targets, and this effect decreased with increasing intertrial intervals. Overall, these studies demonstrate how cue- and target-induced effects interact and suggest that modalities do not automatically capture attention as locations do; rather, the MSE is more similar to other task repetition effects.

  13. 19 CFR 206.53 - Investigations to advise the President as to the probable economic effect of reduction...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION NONADJUDICATIVE INVESTIGATIONS INVESTIGATIONS... 19 Customs Duties 3 2011-04-01 2011-04-01 false Investigations to advise the President as to the... Relief Action § 206.53 Investigations to advise the President as to the probable economic effect...

  14. 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.

  15. An investigation of scale effects in family substance abuse treatment programs.

    PubMed

    Lee, A James

    2010-07-05

    This short report investigates scale effects in family substance abuse treatment programs. In Massachusetts, the family substance abuse treatment programs were much more costly than other adult residential treatment models. State officials were concerned that the "scale" or size of these programs (averaging just eight families) was too small to be economical. Although the sample size (just nine programs) was too small to permit reliable inference, the data clearly signalled the importance of "scale effects" in these family substance abuse treatment programs. To further investigate scale effects in family substance abuse treatment programs, data from the Center for Substance Abuse Treatment's (CSAT's) Residential Women and Children and Pregnant and Postpartum Women (RWC-PPW) Demonstration were re-analyzed, focusing on the relationship between cost per family-day and the estimated average family census. This analysis indicates strong economies of scale up until an average family census of about 14, and less apparent scale effects beyond that point. In consideration of these and other study findings, a multidisciplinary interagency team redesigned the Massachusetts' family treatment program model. The new programs are larger than the former family treatment programs, with each new program having capacity to treat 11 to 15 families depending on family makeup.

  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. 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.

  18. Investigating higher order modes effects on thermionic RF gun transverse emittance

    NASA Astrophysics Data System (ADS)

    Rajabi, A.; Shokri, B.; Feghhi, S. A. H.

    2017-02-01

    As the excitation of higher order modes in high gradient accelerating cavities of the RF gun negatively influences electron beam quality, in the present work a theory is obtained based on generalizing Panofsky-Wenzel theorem to study the effect of transverse magnetic modes on transverse emittance growth of the RF gun. Based on this theory, the impact of higher order modes on transverse momentum is investigated. Based on analysis and simulation results, it is shown that different RF modes result in divergence or convergence effects on beam transverse dynamics. The presence of dipole and quadrupole modes can enhance the transverse emittance by 320 % and 450 % , respectively. The compound effect of the presence of two higher order modes results in 470 % transverse emittance growth.

  19. Experimental investigation of the role of the triplet pairing in the superconducting spin-valve effect

    NASA Astrophysics Data System (ADS)

    Leksin, P. V.; Kamashev, A. A.; Garif'yanov, N. N.; Validov, A. A.; Fominov, Ya. V.; Schumann, J.; Kataev, V. E.; Büchner, B.; Garifullin, I. A.

    2016-11-01

    An important role of the morphology of a superconducting layer in the superconducting spin-valve effect has been established. The triplet pairing induced by the superconductor/ferromagnet proximity effect has been experimentally investigated for samples CoO x /Py1/Cu/Py2/Cu/Pb (where Py = Ni0.81Fe0.19) with a smooth superconducting layer. The optimization of the parameters of this structure has demonstrated a complete switching between the normal and superconducting states with a change in the relative orientation of magnetizations of the ferromagnetic layers from the antiparallel to orthogonal orientation. A pure triplet contribution has been observed for the sample with a permalloy layer thickness at which the superconducting spin-valve effect vanishes. A direct comparison of the experimental data with the theoretical calculation of the temperature of the transition to the superconducting state has been performed for the first time.

  20. Experimental investigation of nonlinear optical properties of Ag nanoparticles: Effects of size quantization

    NASA Astrophysics Data System (ADS)

    Sato, Rodrigo; Ohnuma, Masato; Oyoshi, Keiji; Takeda, Yoshihiko

    2014-09-01

    The effects of size quantization on the nonlinear optical response of Ag nanoparticles are experimentally studied by spectroscopic ellipsometry and femtosecond spectroscopic pump-and-probe techniques. In the vicinity of a localized surface-plasmon resonance (2.0-3.5 eV), we have investigated the optical nonlinearity of Ag particles embedded in silica glass for particle diameters ranging from 3.0 to 16 nm. The intrinsic third-order optical susceptibility χm(3) of Ag particles exhibited significant spectral and size dependences. These results are explained as quantum and dielectric confinements and are compared to the results of theoretical quantum finite-size effects calculation for metallic particles. In light of these results, we discuss the contribution of interband transitions to the size dependence of χm(3). Quantum size effects lead to an increase in nonlinearity in small Ag particles.

  1. An investigation of unsteady 3D effects on trailing edge flaps

    NASA Astrophysics Data System (ADS)

    Jost, E.; Fischer, A.; Lutz, T.; Krämer, E.

    2016-09-01

    The present study investigates the impact of unsteady and viscous three-dimensional aerodynamic effects on a wind turbine blade with trailing edge flap by means of CFD. Harmonic oscillations are simulated on the DTU 10 MW rotor with a flap of 10% chord extent ranging from 70% to 80% blade radius. The deflection frequency is varied in the range between 1p and 6p. To quantify 3D effects, rotor simulations are compared to 2D airfoil computations. A significant influence of trailing and shed vortex structures has been found which leads to a reduction of the lift amplitude and hysteresis effects in the lift response with regard to the flap deflection. In the 3D rotor results greater amplitude reductions and less hystereses have been found compared to the 2D airfoil simulations.

  2. 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.

  3. 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.

  4. 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.

  5. A laboratory investigation of the thermoelectric effect in clean silica sands

    NASA Astrophysics Data System (ADS)

    Meyer, Clinton

    The effect of thermoelectric coupling on self-potential was investigated by applying a temperature gradient to unconsolidated sands fully saturated by saline (NaCl) solutions. Thus far, very few published investigations have taken into account the effect of temperature on the electrodes and the ionic strength of the pore water, generating spurious diffusion potentials typically on the same order of magnitude as the thermoelectric effect. For this investigation, 25 experiments are conducted to test the influence of salinity upon the thermoelectric coupling coefficient over four orders of magnitude in salinity variation. The intrinsic thermoelectric coefficient ranged from -0.4 mV °C-1 (10-3 M NaCl) to +0.9 mV °C-1 at very low salinities (10-4 M). Silica sands with median grain sizes of 0.72 mm and 0.2 mm were used, with corresponding surface conductivities of 1.52x10-5 (S m -1) and 5.43x10-5 (S m-1) , respectively. In order to isolate the thermoelectric response associated with the temperature gradient, raw self-potential measurements were corrected for the diffusion potentials arising from different ionic strengths within our sand tank using a commonly accepted model. Our experimental data can be reproduced by a simple model accounting for the effect of surface conductivity due to the electrical double layer coating the surface of the grains. Our results indicate that Hittorf transport numbers changing with salinity need to be considered when developing a holistic model. Furthermore, when considering the polarity and magnitude of the thermoelectric response, salinity and grain size are important factors.

  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. Investigating clandestine drug laboratories: adverse medical effects in law enforcement personnel.

    PubMed

    Burgess, J L; Barnhart, S; Checkoway, H

    1996-10-01

    A retrospective cohort study was conducted among an international group of 46 law enforcement chemists and 13 Washington State clandestine drug laboratory investigation team members with more than 2,800 combined investigations. Each participant completed a questionnaire concerning previous drug laboratory investigations and adverse health effects during response activities. Methamphetamine laboratories accounted for 81-97% of all responses. Total illness incident rates varied between 0.75-3.4% of responses. Most exposures were through inhalation, and many occurred in the years prior to use of personal protective equipment. Symptoms were primarily those of headache and respiratory, mucous membrane, and skin irritation. Most illness episodes occurred during the processing phase of laboratory responses, and none occurred during the entry phase. A majority of illness episodes occurred in laboratories with leak/spills, fire/explosion, or uncontrolled reactions. Responding to an active laboratory was associated with a 7 to 15-fold risk of becoming ill as compared with setup, in-transit, or former (equipment removed) laboratory responses. No other laboratories characteristics were consistently associated with a significantly elevated relative risk of adverse health effects.

  8. Investigating the influence of effective parameters on molecular characteristics of bovine serum albumin nanoparticles

    NASA Astrophysics Data System (ADS)

    Rohiwal, S. S.; Satvekar, R. K.; Tiwari, A. P.; Raut, A. V.; Kumbhar, S. G.; Pawar, S. H.

    2015-04-01

    The protein nanoparticles formulation is a challenging task as they are prone to undergo conformational transitions while processing which may affect bioavailability for bioactive compounds. Herein, a modified desolvation method is employed to prepare Bovine Serum Albumin nanoparticles, with controllable particle size ranging from 100 to 300 nm and low polydispersity index. The factors influencing the size and structure of BSA NPs viz. protein concentration, pH and the conditions for purification are well investigated. The structure of BSA NPs is altered due to processing, and may affect the effective binding ability with drugs and bioactive compounds. With that aims, investigations of molecular characteristics of BSA NPs are carried out in detail by using spectroscopic techniques. UV-visible absorption and Fourier Transform Infrared demonstrate the alteration in protein structure of BSA NPs whereas the FT-Raman spectroscopy investigates changes in the secondary and tertiary structures of the protein. The conformational changes of BSA NPs are observed by change in fluorescence intensity and emission maximum wavelength of tryptophan residue by fluorescence spectroscopy. The field emission scanning electron and atomic force microscopy micrographs confirm the size and semi-spherical morphology of the BSA NPs. The effect of concentration and pH on particle size distribution is studied by particle size analyzer.

  9. Experimental investigation on the effects of normal stress on fracture propagation and slip instability

    NASA Astrophysics Data System (ADS)

    Ougier-Simonin, A.; Zhu, W.

    2011-12-01

    Recent discoveries of slow slip phenomena, from low frequency earthquakes to episodic tremor and slip events, create new challenges to our understanding of source processes. High pore pressure is often cited as the likely cause for these slow slip events. The working hypothesis is that pore pressure excess reduces effective normal stress on the fault plane thus generates slip instability. However, experimental evidence on whether and how different slip instabilities results from high pore pressure is still missing. In this study, we conducted triaxial deformation experiments to investigate how the reduction of effective normal stress affects slip instability and fracture propagation. Porous sedimentary rocks were deformed at constant strain rates and under fully drained conditions. We designed loading configurations so that brittle failure and frictional instability in samples deformed under decreasing effective stress can be compared to those under increasing effective stress. Our experimental results indicate that, 1) effects of loading configuration and strain rate on the brittle strength is negligible; 2) the slip distance during fracture nucleation is sensitive to strain rate and loading path; 3) shear fracture energy released during fracture propagation is a function of slip. However, fracture propagation in samples deformed under decreasing effective normal stress tend to be more stable, which bears similar characteristics with slow slip events. The observed slip instability under decreasing normal stress can be modeled using a theoretical framework proposed by Dieterich and Linker [1992]. Quantitative microstructural analysis was performed on samples undergone different stages of failure to characterize the progressive damage during fracture propagation.

  10. The investigation of transient thermal effects in optical elements under high laser intensities

    NASA Astrophysics Data System (ADS)

    Kaskow, Mateusz; Tarka, Jan; Kwiatkowski, Jacek; Zendzian, Waldemar; Gorajek, Lukasz; Jabczynski, Jan K.

    2012-06-01

    The most important limitations in development of high energy and high power lasers based on solid state technology are thermal effects occurring under high intensity and high heat loads. The thermo-optical effects occurring inside output couplers, folding mirrors, output windows can significantly diminish the beam quality of high power lasers and therefore have to be investigated. The knowledge on transient thermal effects occurring inside bulk laser elements exposed on laser intensities of several dozens of kW/cm2 is of special interest for some specific applications (e.g. heat capacity lasers). The aims of work were theoretical analysis of those effects occurring inside the laser mirrors and its experimental verification. The hints for choice of the best materials (from the point of view of thermal limitations) for laser windows and output couplers were pointed out. The special laboratory setup enabling simultaneous registration of thermo-optical effects applying shearing interferometry and wavefront sensing by means of Shack-Hartmann test was worked out. The transient as well as averaged in time thermal-optical effects occurring inside the volume of examined element as a result of surface absorption in the coatings and bulk absorption in the material can be resolved and measured. The resolution of measurements: less than 0.1 K temperature difference and thermally induced optical power of about 0.1 D were demonstrated.

  11. 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.

  12. Effects of spanwise camber on delta wing aerodynamics: An experimental and theoretical investigation

    NASA Astrophysics Data System (ADS)

    Traub, Lance Wayne

    1999-12-01

    An experimental and theoretical investigation into the effects of spanwise camber on delta wings is described. Twenty four flat plate delta wings, encompassing various spanwise camber variations were examined. Testing comprised force balance, surface pressure measurement, 7- hole probe surveys, on-surface flow visualization and measurement of vortex burst trajectories. The low speed experimental investigation was conducted in Texas A&M University's 3' x 4' low speed wind tunnel and a 2' x 3' water tunnel. Theoretical methods developed include an explicit analytic method to predict the lift of spanwise cambered delta wings of constant camber, as well as various other methods to predict the characteristics of vortex flows and their effects on delta wing aerodynamics. The investigation shows that the net effect of non-planarity is an increase in lift for anhedral and a decrease in lift for dihedral compared to the planar wing, with these effects increasing with wing sweep. Consequently, anhedral shows the greatest benefit for most applications. Small anhedral angles are most effective in augmenting lift. Anhedral increases wing efficiency over a comparative planar wing. Anhedral does not, appear to greatly augment the strength of the leading edge vortex as demonstrated by data detailing vortex circulation and from peak surface loading from surface pressures. The major benefit from anhedral would appear to be due to its displacing effect on the vortex trajectory: both drawing it closer to the wing surface and inboard. As the vortex is drawn inboard, its induced surface loading acts on a greater area of the wing. In addition anhedral does not appear to introduce any detrimental effects on longitudinal stability, and does not incur any penalties in terms of vortex burst characteristics. Somewhat surprisingly, although limited in scope, the present variations in the distribution of spanwise camber suggest that camber is most beneficial applied near the wing tips: as is

  13. Elasticity and magnetocaloric effect in MnFe4Si3

    SciTech Connect

    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 compounds 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.

  14. 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).

  15. 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.

  16. 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.

  17. Investigation of age and gender effects on positive orientation in Italian twins.

    PubMed

    Fagnani, Corrado; Medda, Emanuela; Stazi, Maria A; Caprara, Gian V; Alessandri, Guido

    2014-12-01

    We investigated age and gender effects on "Positive Orientation" (POS)-an individual's tendency to view life with a positive outlook-using a genetically informed design. Study subjects were 1016 twins aged 22-75 from the Italian twin registry. We assessed POS by the recently developed P-scale. First, we used confirmatory factor analysis to investigate scale's measurement invariance by age and gender. Then, we applied biometric modelling to estimate genetic and environmental components of POS score. Overall, we found a satisfactory degree of measurement invariance by both age and gender. Results from these analyses further indicated an increasing mean level of POS across the lifespan. Additive genetic and unshared environmental factors explained respectively 58% and 42% of variance in POS score, with no significant gender differences; furthermore, the pattern of change of gene-environment architecture of POS over time was consistent with a greater plasticity of personality at older ages.

  18. 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)

  19. A quantitative investigation of the effect of pore morphology on soil aggregate stability

    NASA Astrophysics Data System (ADS)

    Papadopoulos, A.

    2009-04-01

    Soil structure determines the operating environment for all physical, chemical and biological processes within the soil. Soil aggregate stability is an important measure for assessing soil structure quality. Non-destructive tomography techniques such as X-ray Computed Tomography (CT) offer great opportunities to quantitatively investigate the soil porous architecture which can provide important information for understanding soil processes and function in a multi-scale manner. For instance, the intra-aggregate pore space is of great importance for microbial activity, the sequestration of organic carbon and water flow. This paper investigates the effect of pore morphology on soil aggregate stability. Apparent porosity, pore size distribution, average pore size and fractal perimeter dimension (pore roughness) were measured from the images of the reconstructed 2-D image stacks. A new theoretical concept of soil aggregate stability is proposed. A strong relationship was observed between soil aggregate stability and pore morphological complexity.

  20. Investigation of the Neutral Gas Pressure Effect on the Metal Resistive Bolometer

    SciTech Connect

    Zhang, D.; Giannone, L.; Piechotka, M.; Windisch, T.; Klinger, T.; Grulke, O.; Stark, A.

    2008-03-19

    The bolometer system planned for W7-X consists mainly of metal (Au) resistive detector arrays. All the detectors are exposed to neutral gas environment. The thin bolometer foil used for detecting the radiated power loss may be sensitive to the neutral gas pressure due to the strain gauge effect. Recently, a prototype of this kind of bolometer camera consisting of 12 channels has been installed on the cylindrical plasma device VINETA in order to investigate the influences of the neutral gas pressure on the bolometer signals. Experiments are carried out for Ar-discharges under different gas pressure conditions. It is found that the pressure effect of the neutral gas can make considerable contributions, thus inducing non-negligible errors of the results in most of the investigated cases. Using the VINETA plasmas (Ar, T{sub e}<10 eV, n{sub e}<10{sup -19} m{sup -3}) as examples, the paper demonstrates and discusses how to minimize the neutral gas effects, especially in the data analysis process. The radiated power and the radiation intensity profile obtained in helicon discharges are presented.

  1. 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.

  2. 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.

  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 geometrical effects in the carbon allotropes manipulation based on AFM: multiscale approach

    NASA Astrophysics Data System (ADS)

    Korayem, M. H.; Hefzabad, R. N.; Homayooni, A.; Aslani, H.

    2017-01-01

    Carbon allotropes are used as nanocarriers for drug and cell delivery. To obtain an accurate result in the nanoscale, it is important to use a precise model. In this paper, a multiscale approach is presented to investigate the manipulation process of carbon allotropes based on atomic force microscopy (AFM). For this purpose, the AFM setup is separated into two parts with different sizes as macro field (MF) and nano field (NF). Using Kirchhoff's plate model, the cantilever (the main part of MF) is modeled. The molecular dynamics method is applied to model the NF part, and then the MF and NF are coupled with the multiscale algorithm. With this model, by considering the effect of size and shape, the manipulation of carbon allotropes is carried out. The manipulations of armchair CNTs and fullerenes are performed to study the diameter changing effects. The result shows that the manipulation and friction force increases by increasing the diameter. The result of the indentation depth for the armchair CNTs indicates that decreasing the diameter causes the indentation depth to reduce. Moreover, the manipulations of four kinds of carbon allotropes with the same number of atoms have been studied to investigate the geometrical effects. The shapes of these nanoparticles change from sphere to cylinder. The results illustrate that the manipulation and the friction force decrease as the nanoparticle shape varies from sphere to cylinder. The Von-Mises results demonstrate that by changing the nanoparticle shape from the spherical to the cylindrical form, the stress increases, although the manipulation force reduces.

  5. Investigation of the bystander effect in MRC5 cells after acute and fractionated irradiation in vitro.

    PubMed

    Soleymanifard, Shokouhozaman; Toossi, Mohammad Taghi Bahreyni; Samani, Roghayeh Kamran; Mohebbi, Shokoufeh

    2014-04-01

    Radiation-induced bystander effect (RIBE) has been defined as radiation responses observed in nonirradiated cells. It has been the focus of investigators worldwide due to the deleterious effects it induces in nonirradiated cells. The present study was performed to investigate whether acute or fractionated irradiation will evoke a differential bystander response in MRC5 cells. A normal human cell line (MRC5), and a human lung tumor cell line (QU-DB) were exposed to 0, 1, 2, and 4Gy of single acute or fractionated irradiation of equal fractions with a gap of 6 h. The MRC5 cells were supplemented with the media of irradiated cells and their micronucleus frequency was determined. The micronucleus frequency after single and fractionated irradiation did not vary significantly in the MRC5 cells conditioned with autologous or QU-DB cell-irradiated media, except for 4Gy where the frequency of micronucleated cells was lower in those MRC5 cells cultured in the media of QU-DB-exposed with a single dose of 4Gy. Our study demonstrates that the radiation-induced bystander effect was almost similar after single acute and fractionated exposure in MRC5 cells.

  6. Experimental investigation of CNT effect on curved beam strength and interlaminar fracture toughness of CFRP laminates

    NASA Astrophysics Data System (ADS)

    Arca, M. A.; Coker, D.

    2014-06-01

    High mechanical properties and light weight structures of composite materials and advances in manufacturing processes have increased the use of composite materials in the aerospace and wind energy industries as a primary load carrying structures in complex shapes. However, use of composite materials in complex geometries such as L-shaped laminates creates weakness at the radius which causes delamination. Carbon nanotubes (CNTs) is preferred as a toughening materials in composite matrices due to their high mechanical properties and aspect ratios. However, effect of CNTs on curved beam strength (CBS) is not investigated in literature comprehensively. The objective of this study is to investigate the effect of CNT on Mode I and Mode II fracture toughness and CBS. L-shaped beams are fabric carbon/epoxy composite laminates manufactured by hand layup technique. Curved beam composite laminates were subjected to four point bending loading according to ASTM D6415/D6415M-06a. Double cantilever beam (DCB) tests and end notch flexure (ENF) tests were conducted to determine mode-I and mode-II fracture toughness, respectively. Preliminary results show that 3% CNT addition to the resin increased the mode-I fracture toughness by %25 and mode-II fracture toughness by %10 compared to base laminates. In contrast, no effect on curved beam strength was found.

  7. Effect of tone-based sound stimulation on balance performance of normal subjects: preliminary investigation.

    PubMed

    Pagnacco, Guido; Klotzek, Adam S; Carrick, Frederick R; Wright, Cameron H G; Oggero, Elena

    2015-01-01

    Sound is known to affect the human brain, hence sound or music therapy is sometimes used to improve a subject's physicaland mental health. In this study, the effects sound stimulation has on balance were investigated by means of computerizeddynamic posturography tests performed with eyes closed on an unstable surface using a CAPS® system, exceeding theInternational Society for Posture and Gait Research (ISPGR) recommended metrological performance standards. Subjectswere tested without listening to any music (baseline), listening to “pure music”, and listening to the same music with differenttones embedded into it (one for each key). We found that different subjects react differently to different tones. Music alonedid not have a statistically significant effect on balance compared to the baseline, but the “best” tone significantly improvedbalance compared to the baseline or the “pure music” conditions. Furthermore, the “worst” tone reduced the balancecompared to “pure music”, but the reduction was not statistically significant relative to the baseline. The results thereforeindicate that, at least relative to balance performance, the tone-based sound stimulation we investigated is effective andinherently safe, but that tone selection depends on the individual subject.

  8. Giant piezoelectric size effects in zinc oxide and gallium nitride nanowires. A first principles investigation.

    PubMed

    Agrawal, Ravi; Espinosa, Horacio D

    2011-02-09

    Nanowires made of materials with noncentrosymmetric crystal structure are under investigation for their piezoelectric properties and suitability as building blocks for next-generation self-powered nanodevices. In this work, we investigate the size dependence of piezoelectric coefficients in nanowires of two such materials - zinc oxide and gallium nitride. Nanowires, oriented along their polar axis, ranging from 0.6 to 2.4 nm in diameter were modeled quantum mechanically. A giant piezoelectric size effect is identified for both GaN and ZnO nanowires. However, GaN exhibits a larger and more extended size dependence than ZnO. The observed size effect is discussed in the context of charge redistribution near the free surfaces leading to changes in local polarization. The study reveals that local changes in polarization and reduction of unit cell volume with respect to bulk values lead to the observed size effect. These results have strong implication in the field of energy harvesting, as piezoelectric voltage output scales with the piezoelectric coefficient.

  9. An Investigation of the Effects of Black Carbon on Precipitation in the Western United States

    NASA Astrophysics Data System (ADS)

    Tseng, Hsien-Liang Rose

    Black carbon (BC), the byproduct of incomplete combustion, is considered to be the second most important anthropogenic climate forcing agent after carbon dioxide. BC warms the atmosphere by absorbing solar radiation (direct effect), alters cloud and precipitation formation by acting as cloud condensation nuclei (indirect effect), and modifies cloud distribution via cloud burn-off (semi-direct effect). Currently, there are large discrepancies in general circulation model estimates of the influence of BC on precipitation. Even less known is how BC changes precipitation on regional scales. In the drought-stricken western United States (WUS), where BC emissions are known to affect the hydrological cycle, an investigation on how BC influences precipitation is warranted. In this study, we employ the Weather Research and Forecasting-Chemistry (WRF Chem) model (version 3.6.0) with the newly chemistry- and microphysics-coupled Fu-Liou-Gu radiation scheme to study how black carbon affects precipitation by separating BC-related effects into direct and semi-direct, and indirect effects. In this three-part study, we use a recent wet year (2005) to investigate black carbon effects. We first examine BC effects during a heavy wintertime heavy precipitation event (7-11 January 2005), a heavy summertime precipitation week for comparison to the wintertime event (20-24 July 2005), and finally, examine these same effects for the months of January to June 2005 to investigate month-long trends. We find that BC suppresses precipitation, predominantly through its direct and semi-direct effects. The direct and semi-direct effects warm the air aloft, and cool the lower levels of the atmosphere (surface dimming) through the reduction of downward shortwave radiation flux at the surface. These changes in vertical temperature increase the stability of the atmosphere and reduce convective precipitation. Convective precipitation reduction accounts for approximately 60 75% of the total

  10. 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.

  11. Investigating the Effect of Gaze Cues and Emotional Expressions on the Affective Evaluations of Unfamiliar Faces

    PubMed Central

    Kashima, Yoshihisa; Howe, Piers D. L.

    2016-01-01

    People look at what they are interested in, and their emotional expressions tend to indicate how they feel about the objects at which they look. The combination of gaze direction and emotional expression can therefore convey important information about people’s evaluations of the objects in their environment, and can even influence the subsequent evaluations of those objects by a third party, a phenomenon known as the emotional gaze effect. The present study extended research into the effect of emotional gaze cues by investigating whether they affect evaluations of the most important aspect of our social environment–other people–and whether the presence of multiple gaze cues enhances this effect. Over four experiments, a factorial within-subjects design employing both null hypothesis significance testing and a Bayesian statistical analysis replicated previous work showing an emotional gaze effect for objects, but found strong evidence that emotional gaze cues do not affect evaluations of other people, and that multiple, simultaneously presented gaze cues do not enhance the emotional gaze effect for either the evaluations of objects or of people. Overall, our results suggest that emotional gaze cues have a relatively weak influence on affective evaluations, especially of those aspects of our environment that automatically elicit affectively valenced reactions, including other humans. PMID:27682017

  12. An fMRI investigation of the effects of attempted naming on word retrieval in aphasia

    PubMed Central

    Heath, Shiree; McMahon, Katie L.; Nickels, Lyndsey A.; Angwin, Anthony; MacDonald, Anna D.; van Hees, Sophia; McKinnon, Eril; Johnson, Kori; Copland, David A.

    2015-01-01

    In healthy controls, picture naming performance can be facilitated by a single prior exposure to the same picture (“priming”). This priming phenomenon is utilized in the treatment of aphasia, which often includes repeated picture naming as part of a therapeutic task. The current study sought to determine whether single and/or multiple exposures facilitate subsequent naming in aphasia and whether such facilitatory effects act through normal priming mechanisms. A functional magnetic resonance imaging paradigm was employed to explore the beneficial effects of attempted naming in two individuals with aphasia and a control group. The timing and number of prior exposures was manipulated, with investigation of both short-term effects (single prior exposure over a period of minutes) and long-term effects (multiple presentations over a period of days). Following attempted naming, both short-term and long-term facilitated items showed improvement for controls, while only the long-term condition showed benefits at a behavioral level for the participants with aphasia. At a neural level, effects of long-term facilitation were noted in the left precuneus for one participant with aphasia, a result also identified for the equivalent contrast in controls. It appears that multiple attempts are required to improve naming performance in the presence of anomia and that for some individuals with aphasia the source of facilitation may be similar to unimpaired mechanisms engaged outside the language network. PMID:26074801

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Investigating the effect of heat treatment on hydrogen permeation behavior of API X-70 steel

    NASA Astrophysics Data System (ADS)

    Shirband, Zeynab; Shishesaz, Mohammad Reza; Ashrafi, Ali

    2012-06-01

    Pipeline steels absorb different amounts of hydrogen during transportation of sour oil and gas. Since hydrogen-related damages such as hydrogen-induced cracking are strongly affected by hydrogen permeation behavior of steels, the purpose of this study determined to investigate hydrogen permeation behavior in API X-70 pipeline steel using electrochemical permeation method. The effect of heat treatment was also considered. It was found that hydrogen diffusivity increased by annealing the X-70 and it was decreased by normalizing. The condition was reverse for hydrogen apparent solubility. Finally, it was concluded that change in hydrogen diffusivity can be attributed to changes in grain size due to heat treatment.

  18. Investigation of reverse short-channel effect with numerical and compact models

    NASA Astrophysics Data System (ADS)

    Wang, Yuwen; Lim, Khee Y.; Qian, Wensheng; Zhou, Xing

    2000-10-01

    In this paper, a physically based reverse short channel effect (RSCE) threshold voltage compact model is investigated and compared with numerical simulation. A new method to predict RSCE using the compact model is given, which is supported by the TCAD data. A wide range of Vth predictions of nchannel MOSFETs with pile-up structures is conducted. Good prediction results are achieved between the RSCE compact model and TCAD data. The results further support the physics-based RSCE mode, which is useful for both circuit simulation and technology development as well as device design.

  19. Experimental investigations on steady wake effects in a high-lift turbine cascade

    NASA Astrophysics Data System (ADS)

    Heinke, Wolfram; König, Sven; Matyschok, Berthold; Stoffel, Bernd; Fiala, Andreas; Heinig, Klaus

    2004-10-01

    This paper reports on the investigation of steady wake effects in cascades. An annular cascade rig, where two stators having the same blade pitch can be circumferentially traversed relatively to each other, is used to analyse the profile losses and the boundary layer development of the downstream stator for different circumferential positions of the upstream stator (“clocking positions”). Different measurement techniques are used such as three-hole pressure probes, and hot wire- and surface-mounted hot-film probes. The results show a varying pressure loss coefficient of the downstream cascade (S2) for different clocking positions of the upstream cascade (S1_SP).

  20. Roll Forming of AHSS: Numerical Simulation and Investigation of Effects of Main Process Parameters on Quality

    NASA Astrophysics Data System (ADS)

    Salonitis, Konstantinos; Paralikas, John; Chryssolouris, George

    The roll forming process is one of the main processes of producing straight profiles in many industrial sectors. The introduction of Advanced High Strength Steels (AHSS), such as the DP and TRIP-series, into the production of roll-formed profiles has emerged new challenges. The combination of a higher yield strength with a lower total elongation of AHSS, brings new challenges to the roll forming process. In the current study, the numerical simulation of a V-section profile has been implemented. The effect of the main process parameters, such as the roll forming line velocity, rolls inter-distance, roll gap and rolls diameter on quality characteristics is investigated.

  1. Effects of dietary supplementation on autoimmunity in the MRL/lpr mouse: a preliminary investigation.

    PubMed

    Godfrey, D G; Stimson, W H; Watson, J; Belch, J F; Sturrock, R D

    1986-12-01

    The effects of dietary fatty acid supplementation on various disease parameters in the spontaneously autoimmune MRL-mp-lpr/lpr mouse model of systemic lupus erythematosus before onset of disease were investigated. A fat deficient diet was supplemented with the following oils: olive oil, sunflower oil, evening primrose oil (EPO), fish oil, and a fish oil/EPO mixture. The mice receiving a diet enriched with EPO showed an increase in survival, as did those receiving the fish oil/EPO mixture. These results, taken together with those of the other parameters monitored, suggest that EPO may be of benefit in alleviating the murine form of the disease.

  2. Effects of dietary supplementation on autoimmunity in the MRL/lpr mouse: a preliminary investigation.

    PubMed Central

    Godfrey, D G; Stimson, W H; Watson, J; Belch, J F; Sturrock, R D

    1986-01-01

    The effects of dietary fatty acid supplementation on various disease parameters in the spontaneously autoimmune MRL-mp-lpr/lpr mouse model of systemic lupus erythematosus before onset of disease were investigated. A fat deficient diet was supplemented with the following oils: olive oil, sunflower oil, evening primrose oil (EPO), fish oil, and a fish oil/EPO mixture. The mice receiving a diet enriched with EPO showed an increase in survival, as did those receiving the fish oil/EPO mixture. These results, taken together with those of the other parameters monitored, suggest that EPO may be of benefit in alleviating the murine form of the disease. PMID:3492970

  3. 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.

  4. Numerical investigation of the effects of shear waves in transcranial photoacoustic tomography with a planar geometry

    PubMed Central

    Wang, Lihong V.

    2012-01-01

    Abstract. Using a recently developed reconstruction method for photoacoustic tomography (PAT) valid for a planar measurement geometry parallel to a layered medium, we investigate the effects of shear wave propagation in the solid layer upon the ability to estimate Fourier components of the object. We examine this ability as a function of the thickness of the layer supporting shear waves as well as of the incidence angle of the field in the planewave representation. Examples are used to demonstrate the importance of accounting for shear waves in transcranial PAT. Error measures are introduced to quantify the error found when omitting shear waves from the forward model in PAT. PMID:22734745

  5. 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.

  6. Wind tunnel investigation of helicopter rotor wake effects on three helicopter fuselage models

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Mineck, R. E.

    1974-01-01

    The effects of rotor downwash on helicopter fuselage aerodynamic characteristics were investigated. A rotor model for generating the downwash was mounted close to each of three fuselage models. The main report presents the force and moment data in both graphical and tabular form and the pressure data in graphical form. This supplement presents the pressure data in tabular form. Each run or parameter sweep is identified by a unique run number. The data points in each run are identified by a point number. The pressure data can be matched to the force data by matching the run and point number.

  7. 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

  8. Acute effects of cocaine and cannabis on response inhibition in humans: an ERP investigation.

    PubMed

    Spronk, Desirée B; De Bruijn, Ellen R A; van Wel, Janelle H P; Ramaekers, Johannes G; Verkes, Robbert J

    2016-11-01

    Substance abuse has often been associated with alterations in response inhibition in humans. Not much research has examined how the acute effects of drugs modify the neurophysiological correlates of response inhibition, or how these effects interact with individual variation in trait levels of impulsivity and novelty seeking. This study investigated the effects of cocaine and cannabis on behavioural and event-related potential (ERP) correlates of response inhibition in 38 healthy drug using volunteers. A double-blind placebo-controlled randomized three-way crossover design was used. All subjects completed a standard Go/NoGo task after administration of the drugs. Compared with a placebo, cocaine yielded improved accuracy, quicker reaction times and an increased prefrontal NoGo-P3 ERP. Cannabis produced opposing results; slower reaction times, impaired accuracy and a reduction in the amplitude of the prefrontal NoGo-P3. Cannabis in addition decreased the amplitude of the parietally recorded P3, while cocaine did not affect this. Neither drugs specifically affected the N2 component, suggesting that pre-motor response inhibitory processes remain unaffected. Neither trait impulsivity nor novelty seeking interacted with drug-induced effects on measures of response inhibition. We conclude that acute drug effects on response inhibition seem to be specific to the later, evaluative stages of response inhibition. The acute effects of cannabis appeared less specific to response inhibition than those of cocaine. Together, the results show that the behavioural effects on response inhibition are reflected in electrophysiological correlates. This study did not support a substantial role of vulnerability personality traits in the acute intoxication stage.

  9. Numerical investigation of non-equilibrium effects in hypersonic turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Kim, Pilbum; Kim, John; Zhong, Xiaolin; Eldredge, Jeff

    2014-11-01

    Direct numerical simulations of a spatially developing hypersonic boundary layer have been conducted in order to investigate thermal and chemical non-equilibrium effects in a hypersonic turbulent boundary layer. Two different flows, pure oxygen and pure nitrogen flows with specific total enthalpy, h0 ,O2 = 9 . 5017 MJ/kg and h0 ,N2 = 19 . 1116 MJ/kg, respectively, have been considered. The boundary edge conditions were obtained from a separate calculation of a flow over a blunt wedge at free-stream Mach numbers M∞ ,O2 = 15 and M∞ ,N2 = 20 . The inflow conditions were obtained from a simulation of a turbulent boundary layer of a perfect gas. Non-equilibrium effects on turbulence statistics and near-wall turbulence structures were examined by comparing with those obtained in a simulation of the same boundary layer with a perfect-gas assumption.

  10. EPR investigation on radiation-induced graft copolymerization of styrene onto polyethylene: Energy transfer effects

    NASA Astrophysics Data System (ADS)

    Salih, M. A.; Buttafava, A.; Ravasio, U.; Mariani, M.; Faucitano, A.

    2007-08-01

    In this paper, energy transfer phenomena concerning the in-source graft copolymerization of styrene onto LDPE were investigated through the EPR analysis of the radical intermediates. The model solution experiments have shown a substantial deviation of the experimental G (radicals) values with respect to the additivity law, which reflect the negative effect of the styrene monomer concentration on the initiation rate of the graft copolymerization. The EPR measurements performed on polyethylene- co-styrene graft copolymers of various composition following low-temperature vacuum gamma irradiation have confirmed the decrease of the total radical yields with increasing the styrene concentration. The effect was partly attributed to the heterogeneity of the graft copolymer matrix and to the lack of molecular mobility in the solid state at low temperature, which prevents the attainment of the favourable geometrical configurations in intermolecular energy and charge transfer events.

  11. [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.

  12. 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.

  13. Investigating the sonophoresis effect on the permeation of diclofenac sodium using 3D skin equivalent.

    PubMed

    Aldwaikat, Mai; Alarjah, Mohammed

    2015-01-01

    Ultrasound temporally increases skin permeability by altering stratum corneum SC function (sonophoresis). The objective of this study was to evaluate the effect of variable ultrasound conditions on the permeation of diclofenac sodium DS with range of physicochemical properties through EpiDerm™. Permeation studies were carried out in vitro using Franz diffusion cell. HPLC method was used for the determination of the concentration of diclofenac sodium in receiving compartment. Parameters like ultrasound frequency, application time, amplitude, and mode of sonication and distance of ultrasound horn from skin were investigated, and the conditions where the maximum enhancement rate obtained were determined. Application of ultrasound enhanced permeation of diclofenac sodium across EpiDerm™ by fivefolds. The most effective enhancing parameters were power sonication of 20kHz frequency, 20% amplitude at continuous mode for 5min.

  14. Solvent effect on the vibrational spectrum of Michler's ketone. Experimental and theoretical investigations.

    PubMed

    Sowula, Marta; Misiaszek, Tomasz; Bartkowiak, Wojciech

    2014-10-15

    We examined solvent effect on the IR and Raman spectra of MK in several solvents of different polarity and proticity, for understanding of intermolecular interactions, focusing on solvent effect in detail. It has been found that change of solvent polarity has an ambiguous influence on solvatochromism of MK. We have observed that not only vibrations of carbonyl group are affected by the solvent polarity, but also mode ν(CN) and ν(CC) in IR and Raman spectra of MK. Experimental investigations have been supported by the quantum-mechanical computations to gain more insight into the solvatochromic behavior of Michler's ketone. Calculations have been carried using Kohn-Sham formulation of Density Functional Theory (DFT) and the Polarizable Continuum Model (PCM) was employed to account for solute solvent interactions.

  15. 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.

  16. Experimental investigation on the sensible effectiveness of LiCl wheel

    NASA Astrophysics Data System (ADS)

    Rabah, A. A.; Fekete, A.; Kabelac, S.

    2011-04-01

    Experimental investigation on the sensible effectiveness of LiCl wheel is reported. The measurements were made for balanced flow (C* = 1) for a wide range of rotational speed 0-10 rpm, regeneration temperature of 50-70°C and airflow rate 150-550 kg/h. The results revealed that the operation rotational speed for LiCl wheel is about 5 rpm which is significantly lower that for Silica gel wheel. It is also found that the sensible effectiveness is independent of the regeneration temperature. The experimental results are also fitted to the existing correlation of Simonson et al. (ASHRAE Trans 106(1):301-310, 2000). For the range of the applicability of the correlation, most of the experimental data fit the correlation within an error band of ±5%.

  17. Piloted simulator investigation of helicopter control systems effects on handling qualities during instrument flight

    NASA Technical Reports Server (NTRS)

    Forrest, R. D.; Chen, R. T. N.; Gerdes, R. M.; Alderete, T. S.; Gee, D. R.

    1979-01-01

    An exploratory piloted simulation was conducted to investigate the effects of the characteristics of helicopter flight control systems on instrument flight handling qualities. This joint FAA/NASA study was motivated by the need to improve instrument flight capability. A near-term objective is to assist in updating the airworthiness criteria for helicopter instrument flight. The experiment consisted of variations of single-rotor helicopter types and levels of stability and control augmentation systems (SCAS). These configurations were evaluated during an omnirange approach task under visual and instrument flight conditions. The levels of SCAS design included a simple rate damping system, collective decoupling plus rate damping, and an attitude command system with collective decoupling. A limited evaluation of stick force versus airspeed stability was accomplished. Some problems were experienced with control system mechanization which had a detrimental effect on longitudinal stability. Pilot ratings, pilot commentary, and performance data related to the task are presented.

  18. Controlled doping of silicon nanocrystals investigated by solution-processed field effect transistors.

    PubMed

    Gresback, Ryan; Kramer, Nicolaas J; Ding, Yi; Chen, Ting; Kortshagen, Uwe R; Nozaki, Tomohiro

    2014-06-24

    The doping of semiconductor nanocrystals (NCs), which is vital for the optimization of NC-based devices, remains a significant challenge. While gas-phase plasma approaches have been successful in incorporating dopant atoms into NCs, little is known about their electronic activation. Here, we investigate the electronic properties of doped silicon NC thin films cast from solution by field effect transistor analysis. We find that, analogous to bulk silicon, boron and phosphorus electronically dope Si NC thin films; however, the dopant activation efficiency is only ∼10(-2)-10(-4). We also show that surface doping of Si NCs is an effective way to alter the carrier concentrations in Si NC films.

  19. Zeeman effect of weak La I lines investigated by the use of optogalvanic spectroscopy

    NASA Astrophysics Data System (ADS)

    Sobolewski, Ł. M.; Windholz, L.; Kwela, J.

    2017-03-01

    New Landé- gJ factors of 35 energy levels of La I, found from investigations of 40 spectral lines in the wavelength range 562.959÷609.537 nm, were determined. As a source of free La atoms a hollow cathode discharge lamp was used. We monitored the signal of the optogalvanic effect appearing when a laser beam is passing through the hollow cathode. Spectra were recorded in the presence of a magnetic field of about 800 G produced by a permanent magnet, for two linear polarizations of the exciting laser light. Optogalvanic spectroscopy is a very sensitive method, so we were able to observe the Zeeman effect of very weak atomic lines. In this way we have determined for the first time the Landé-gJ factors for 35 recently found levels of neutral La. The Landé gJ- factors for several other levels were reinvestigated.

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. Theoretical Investigation of Substituent Effects on the Dihydroazulene/Vinylheptafulvene Photoswitch: Increasing the Energy Storage Capacity.

    PubMed

    Hansen, Mia Harring; Elm, Jonas; Olsen, Stine T; Gejl, Aske Nørskov; Storm, Freja E; Frandsen, Benjamin N; Skov, Anders B; Nielsen, Mogens Brøndsted; Kjaergaard, Henrik G; Mikkelsen, Kurt V

    2016-12-15

    We have investigated the effects of substituents on the properties of the dihydroazulene/vinylheptafulvene photoswitch. The focus is on the changes of the thermochemical properties by placing electron withdrawing and donating groups on the monocyano and dicyano structures of the parent dihydroazulene and vinylheptafulvene compounds. We wish to increase the energy storage capacity, that is, the energy difference between the dihydroazulene and vinylheptafulvene isomers, of the photoswitch by computational molecular design and have performed over 9000 electronic structure calculations using density functional theory. Based on these calculations, we obtain design rules for how to increase the energy storage capacity of the photoswitch. Furthermore, we have investigated how the activation energy for the thermally induced vinylheptafulvene to dihydroazulene conversion depends on the substitution pattern, and based on these results, we have outlined molecular design considerations for obtaining new desired target structures exhibiting long energy storage times. Selected candidate systems have also been investigated in terms of optical properties to elucidate how sensitive the absorption maxima are to the functionalizations.

  5. 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.

  6. 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

  7. 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.

  8. Investigations of the Effects of Distortion on Trajectory of Diesel Particulate Matter (PM)

    NASA Astrophysics Data System (ADS)

    Rahai, Hamid; Ehsan Shamloo Team

    2011-11-01

    Exposures to diesel PM within urban areas have resulted in elevated respiratory illnesses and risk of premature cardiac death. The present investigation is part of our continuous efforts to understand the relationship between diesel exhausts concentrations and local urban aerodynamics, in metropolitan areas where significant diesel vehicle activities are present. Wind tunnel experiments and field tests were performed to understand the effects of distortion caused by building structures on trajectory of the diesel PM, emitted from diesel engine exhausts in cross flows. Our previous similar investigations without distortion have shown a linear decay in PM concentration with a 10 percent slope. However, when the structures were present, PM concentration increased significantly up to 1d upstream of the object, before it decreases due to the blockage effect. A mathematical correlation based on experimental data has been proposed to estimate the concentration of the diesel PM with respect to the wind velocity at different distances upstream of the objects. This study was supported with a grant from METRANS research program.

  9. 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.

  10. A research model for investigating the effects of artificial food colorings on children with ADHD.

    PubMed

    Kleinman, Ronald E; Brown, Ronald T; Cutter, Gary R; Dupaul, George J; Clydesdale, Fergus M

    2011-06-01

    The United Kingdom and European Union recently restricted the use of artificial food colorings (AFCs) to improve the health of children. These decisions provide an interesting case study of the role of scientific evidence in the assessment of food additives and risk to children's health and formulation of food policy. Although there continues to be uncertainty concerning the link between AFCs and attention-deficit/hyperactivity disorder (ADHD), policy decisions have been made that have far-reaching implications. In addition, publicity surrounding the policy changes may shape public perceptions concerning effective management of ADHD. We believe that the balance of existing evidence neither refutes nor supports the link between AFCs and ADHD, which highlights the need for carefully designed studies to further investigate the link between AFCs and ADHD. In this article we describe a model for such studies. In developing our model, we drew from current investigative standards in ADHD research, such as those used in the landmark Multimodal Treatment Study of Children With ADHD. These standards encompass methodologic considerations including sample selection, outcome assessment, and data analyses. It is our hope that this model research methodology may prove valuable in addressing design considerations in future studies of AFCs and ADHD with the goal of producing reliable data that will enable policy-makers to better formulate effective, evidence-based food-policy decisions.

  11. An Investigation on the Effect of Extremely Low Frequency Pulsed Electromagnetic Fields on Human Electrocardiograms (ECGs)

    PubMed Central

    Fang, Qiang; Mahmoud, Seedahmed S.; Yan, Jiayong; Li, Hui

    2016-01-01

    For this investigation, we studied the effects of extremely low frequency pulse electromagnetic fields (ELF-PEMF) on the human cardiac signal. Electrocardiograms (ECGs) of 22 healthy volunteers before and after a short duration of ELF-PEMF exposure were recorded. The experiment was conducted under single-blind conditions. The root mean square (RMS) value of the recorded data was considered as comparison criteria. We also measured and analysed four important ECG time intervals before and after ELF-PEMF exposure. Results revealed that the RMS value of the ECG recordings from 18 participants (81.8% of the total participants) increased with a mean value of 3.72%. The increase in ECG voltage levels was then verified by a second experimental protocol with a control exposure. In addition to this, we used hyperbolic T-distributions (HTD) in the analysis of ECG signals to verify the change in the RR interval. It was found that there were small shifts in the frequency-domain signal before and after EMF exposure. This shift has an influence on all frequency components of the ECG signals, as all spectrums were shifted. It is shown from this investigation that a short time exposure to ELF-PEMF can affect the properties of ECG signals. Further study is needed to consolidate this finding and discover more on the biological effects of ELF-PEMF on human physiological processes. PMID:27886102

  12. 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.

  13. 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.

  14. Numerical investigation on red blood cell dynamics in microflow: Effect of cell deformability.

    PubMed

    Ju, Meongkeun; Leo, Hwa Liang; Kim, Sangho

    2017-01-01

    The radial dispersion of red blood cells (RBCs) near the vessel wall can significantly affect the transport dynamics in small vessels. The radial dispersion of RBCs is mainly caused by collisions between RBCs and this can be enhanced by aggregation. The objective of this study is to numerically investigate on the effect of RBC deformability on the radial motion of individual RBCs in a range of flow rates. Immersed Boundary - Lattice Boltzmann Method was utilized to study the radial motion of RBCs in a two-dimensional flow domain. The RBC flow simulations were performed at 40% hematocrit in a microvessel with diameter of 25μm and length of 100μm. The dispersion of less deformable RBCs was notably greater than that of normal RBCs at all flow rates and this effect seemed to be more pronounced when the flow rate was increased. The cell dispersion was higher near the vessel wall than the flow center regardless of flow rate and RBCs deformability. Thus, the dispersion of RBCs could be enhanced with flow rate and RBC rigidity. Our findings would be especially useful in investigating blood flows in arterioles and venules.

  15. 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.

  16. Investigating the Effects of "Cool" Solar Reflective Pavements on California Climate

    NASA Astrophysics Data System (ADS)

    Mohegh, M.; Ban-Weiss, G. A.; Levinson, R.; Rosado, P.

    2015-12-01

    Implementing "Cool pavement" is a local mitigation strategy that can reduce urban heat islands. We investigated the climate impacts of widespread deployment of cool pavements by increasing the albedo of the pavements from 0.1 to 0.5 to understand the efficiency of cool pavements in reducing the temperature in California's urban areas. A validated parameterization of WRF model coupled with Single Layer Urban Canopy Model (SLUCM) is employed to simulate the effects of pavements at the bottom of canopy on urban heat islands. The results show local surface air temperature reductions, peaking at late morning and late evening which coincides with the lowest boundary layer height in the day time. Summer time temperature reductions up to 0.62 K in the evening (20:00 local) and 0.32 K in afternoon (14:00) in California are predicted. The cooling effects of 15 cities in California are sampled and analyzed. The average temperature reductions for the cities in California show 0.32 K temperature reduction per 0.1 total albedo reduction in the afternoon (14:00) which is consistent with the previous works. The linear relation between temperature reductions and the albedo increase is used to estimate the effect of cool pavements in "No Canopy" state, which can be used as an upper bound of the effects of cool pavements.

  17. 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

  18. 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.

  19. Investigation of Recessive Effects in Schizophrenia Using Next-Generation Exome Sequence Data.

    PubMed

    Curtis, David

    2015-03-27

    A number of gene-wise approaches to analysis were applied to whole exome sequence data from 2545 Swedish schizophrenia cases with 2545 matched controls. A weighted burden test was used to detect dominant and additive effects. Recessive effects were investigated by testing whether there was an excess of cases bearing two or more rare, functional variants or whether there was an excess of cases in which both phased haplotypes carried at least one rare, functional variant. Counts for cases were compared with controls and also with the expectation under Hardy-Weinberg equilibrium. Analyses were performed using the SCOREASSOC program. No gene produced statistically significant results although COMT was highly ranked by the weighted burden test and within it the Ala72Ser polymorphism rs6267 had an uncorrected p value of 0.00003. A number of spurious results were generated, some apparently due to miscalling of homozygotes and others due to a failure to eradicate the effects of linkage disequilibrium between variants. These problems were not marked when using phased haplotypes but this method failed to produce any significant or suggestive findings. If there are exonic variants with recessive effects on the risk of schizophrenia, then the methods used were unable to detect them.

  20. Ultrastructural investigation of the protective effects of propolis on bleomycin induced pulmonary fibrosis.

    PubMed

    Bilgin, G; Kismet, K; Kuru, S; Kaya, F; Senes, M; Bayrakceken, Y; Yumusak, N; Celikkan, F T; Erdemli, E; Celemli, O G; Sorkun, K; Koca, G

    2016-01-01

    We investigated the antioxidant and anti-inflammatory effects of propolis on bleomycin induced lung fibrosis and compared these effects to prednisolone treatment. Forty rats were divided into four groups of ten: group 1 was treated with intratracheal infusion of 0.2 ml physiological saline followed by daily treatment with 0.5 ml physiological saline for 20 days. In the remaining groups (groups 2 - 4), 5 mg/kg bleomycin was given via the trachea. Rats in group 2 were given 0.5 ml physiological saline. Rats in group 3 were treated with 100 mg/kg propolis, and 10 mg/kg prednisolone was given to rats in group 4. The treatments for all groups were continued for 20 days. On postoperative day 21, blood and lung samples were taken for biochemistry, histopathology and electron microscopy evaluation. We compared oxidative stress parameters and found lower malondialdehyde and myeloperoxidase levels, and higher total sulfhydryl levels and catalase activities for the bleomycin + propolis group than for the bleomycin and bleomycin + prednisolone groups. The highest mean fibrosis score was detected in the bleomycin group. Although the mean fibrosis scores of the bleomycin + propolis and bleomycin + prednisolone groups were not significantly different, electron microscopy revealed that propolis diminished bleomycin induced lung fibrosis more effectively than prednisolone. The effects of propolis might be due to its potent antioxidant and anti-inflammatory properties.

  1. 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.

  2. Theoretical Investigations of the Effects of Lithium Intercalation on the Properties of Indium Selenide

    NASA Astrophysics Data System (ADS)

    Gomes da Costa, Manuel Pedro Fernandes

    The effect of intercalating lithium into gamma-InSe and beta -InSe has been investigated. The energy bands of pure gamma -InSe and pure beta-InSe were calculated using an overlap-reduced semi-empirical tight-binding method. The parameters for the interactions of Li atoms with In and Se atoms were obtained using the atomic wave-functions of Clementi and Roetti and the Heine-Abarenkov model potential. We established the positions of minimum potential inside the unit cell of the two InSe polytypes where the lithium atoms are most likely to be found. By placing lithium atoms in these sites, we calculated the modifications of the energy bands produced by the introduction of one Li atom per unit cell in gamma-InSe and two lithium atoms per unit cell in beta -InSe. The activation energy for movement of a Li atom between local energy minima was also calculated. The results have been correlated with the optical absorption and photoluminescence data of InSe and Li-intercalated InSe. The lattice dynamics of both the pure gamma- and beta-polytypes of the layer compound InSe have been investigated using a model containing short-range central forces and long -range Coulomb interactions. The normal mode frequencies and eigenvectors were determined by diagonalizing the dynamical matrix. The results have been correlated with the infrared and Raman spectra in InSe. The procedure was then extended to include one lithium ion per unit cell in a site of minimum potential in both the gamma-InSe and the beta-InSe polytypes. The effect of intercalated Li atoms on the vibrational modes and on the infrared and Raman spectra was then investigated.

  3. Judgement bias in goats (Capra hircus): investigating the effects of human grooming.

    PubMed

    Baciadonna, Luigi; Nawroth, Christian; McElligott, Alan G

    2016-01-01

    Animal emotional states can be investigated by evaluating their impact on cognitive processes. In this study, we used a judgement bias paradigm to determine if short-term positive human-animal interaction (grooming) induced a positive affective state in goats. We tested two groups of goats and trained them to discriminate between a rewarded and a non-rewarded location over nine training days. During training, the experimental group (n = 9) was gently groomed by brushing their heads and backs for five min over 11 days (nine training days, plus two testing days, total time 55 min). During training, the control group (n = 10) did not experience any direct interaction with the experimenter, but was kept unconstrained next to him for the same period of time. After successful completion of the training, the responses (latency time) of the two groups to reach ambiguous locations situated between the two reference locations (i.e., rewarded/non-rewarded) were compared over two days of testing. There was not a positive bias effect after the animals had been groomed. In a second experiment, 10 goats were tested to investigate whether grooming induced changes in physiological activation (i.e., heart rate and heart rate variability). Heart rate increased when goats were groomed compared to the baseline condition, when the same goats did not receive any contact with the experimenter. Also, subjects did not move away from the experimenter, suggesting that the grooming was positively accepted. The very good care and the regular positive contacts that goats received from humans at the study site could potentially account for the results obtained. Good husbandry outcomes are influenced by animals' perception of the events and this is based on current circumstances, past experiences and individual variables. Taking into account animals' individual characteristics and identifying effective strategies to induce positive emotions could increase the understanding and reliability of using

  4. Judgement bias in goats (Capra hircus): investigating the effects of human grooming

    PubMed Central

    Nawroth, Christian

    2016-01-01

    Animal emotional states can be investigated by evaluating their impact on cognitive processes. In this study, we used a judgement bias paradigm to determine if short-term positive human-animal interaction (grooming) induced a positive affective state in goats. We tested two groups of goats and trained them to discriminate between a rewarded and a non-rewarded location over nine training days. During training, the experimental group (n = 9) was gently groomed by brushing their heads and backs for five min over 11 days (nine training days, plus two testing days, total time 55 min). During training, the control group (n = 10) did not experience any direct interaction with the experimenter, but was kept unconstrained next to him for the same period of time. After successful completion of the training, the responses (latency time) of the two groups to reach ambiguous locations situated between the two reference locations (i.e., rewarded/non-rewarded) were compared over two days of testing. There was not a positive bias effect after the animals had been groomed. In a second experiment, 10 goats were tested to investigate whether grooming induced changes in physiological activation (i.e., heart rate and heart rate variability). Heart rate increased when goats were groomed compared to the baseline condition, when the same goats did not receive any contact with the experimenter. Also, subjects did not move away from the experimenter, suggesting that the grooming was positively accepted. The very good care and the regular positive contacts that goats received from humans at the study site could potentially account for the results obtained. Good husbandry outcomes are influenced by animals’ perception of the events and this is based on current circumstances, past experiences and individual variables. Taking into account animals’ individual characteristics and identifying effective strategies to induce positive emotions could increase the understanding and reliability of

  5. 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.

  6. Investigation on the artificial exchange signals induced by the RIDER effect in CODEX experiments.

    PubMed

    Zhang, Rongchun; Chen, Tiehong; Sun, Pingchuan; Li, Baohui; Ding, Datong

    2012-01-01

    The CODEX (center-band only detection of exchange) NMR experiment is widely used for the detection of slow motions in organic solids, especially polymers. However, the RIDER (relaxation-induced dipolar exchange with recoupling) effect may result in artificial exchange signals in the CODEX pure exchange spectrum, which greatly limits the application of CODEX method. Herein, we investigate the distance range that the RIDER effect can reach by performing CODEX experiments on two typical organic solids, hexadecyltrimethylammonium bromide (CTAB) and semi-crystalline polyamide-6 (PA6) where there are no slow molecular motions at room temperature. Our experimental results demonstrate that generally two-bond distance is far enough to ignore the RIDER effect resulted from the dipolar interactions between (13)C and the fast relaxing heteronucleus (14)N. From the built-up curve of RIDER signals as a function of recoupling time and mixing time, it is clearly revealed that the RIDER effect can greatly affect the signal from (13)C directly bonded with (14)N. However, this RIDER effect accounts less than 3% of the reference intensity for signals from (13)C not directly bonded with (14)N if typical recoupling (~0.5 ms) and mixing times (~0.5 s) are used for the investigation of slow motions. When longer recoupling and mixing time are used, there are small RIDER signals even for the (13)C far away from the (14)N. These signals, to a large degree, result from the spin diffusion effect and/or the special microscopic molecule arrangement. However, they are so small compared to the reference signal (~5%) that they can be ignored. Finally, according to the simulation results, it is worth noting that the RIDER signal is still generally negligible compared to the signals due to slow motions if the chemical shift anisotropy reorientation during the mixing time is not too small(larger than 20°) under the condition of 4t(r) recoupling time at the magic-angle-spinning speed of 6.5 kHz.

  7. 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.

  8. 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.

  9. 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.

  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.

  11. Laboratory and Field Investigations of Dynamic Effects in Soil Water Retention Curve

    NASA Astrophysics Data System (ADS)

    Chiu, Yung-Chia; Tseng, Yen-Huiang; Ye, Jiun-Yan

    2015-04-01

    The unsaturated soil is a multi-phase system and the embedded physical mechanisms and chemical reactions are very complicated. The characteristics of groundwater flow and mechanisms of mass transport are still ambiguous so far. In order to fully understand the flow and transport in the unsaturated zone, the soil water retention curve plays an important role in description of water flow. However, the measurements and calculations of soil water retention curve are usually obtained under the static condition or steady state (equilibrium), in which the dynamic effects (non-equilibrium) are not considered, and the obtained relationship between capillary pressure and saturation is skeptical. Therefore, the sandbox experiments and field tests will be conducted to discuss the dynamic effects in the soil water retention curve and hysteresis effect in this study. In the laboratory, the relations between capillary pressure, saturation, the rate of change of water content, and dynamic constant are evaluated through different setting of boundary conditions and different sizes of particles. In the field, the tests are conducted to describe the soil water retention curve through the rain simulator and artificial evaporation. Besides, the dynamic dewpoint potentiameter is used to analyze the hysteresis effect of soil samples, and its results are compared with the results obtained from sandbox and field experiments. Finally, through a series of experiments, the relationship between capillary pressure and saturation under the dynamic effects is established, and the associated theories and mechanisms are discussed. The works developed in this study can provide as reference tools for the hydrogeological investigation and contaminated site remediation in the future. Keywords: capillary pressure, saturation, soil water retention curve, hysteresis, sandbox experiment, field test

  12. 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.

  13. [Investigation of the in vitro antioxidant effect of Petroselinum crispum (Mill.) Nym. ex A. W. Hill].

    PubMed

    Fejes, S; Kéry, A; Blázovics, A; Lugasi, A; Lemberkovics, E; Petri, G; Szöke, E

    1998-05-01

    Free radical reactions have excited excessive research in the past two decades. Since then it has been proven that these mechanisms may be important in the pathogenesis of certain diseases and aging. Many synthetic antioxidant components have shown toxic and/or mutagenic effects, which have directed most of the attention on the naturally occurring antioxidants. Their use has mainly centered around prevention, and the maintenance of health. Parsley, Petroselinum crispum (Mill.) Nym. ex A. W. Hill belonging to the Apiaceae family, is a well-known spice and vegetable. Its herb and root are widely known for their effects on digestion, stomach, kidney, blood, and liver. The essential oil obtained from the fruit has also strong action on the central nervous system. Characteristic constituents are: flavonoids (apiin, luteolin-, apigenin-glycosides), essential oil (apiol, miriszticin), cumarines, (bergapten, imperatorin) and vitamin C. In our experimental work, various extracts prepared from different vegetative organs of parsley have been investigated. The chemical composition of the extracts and fractions were analyzed by chromatographic (GC, HPLC) and spectroscopic (UV, UV-VIS) techniques. We intended to provide evidence for the antioxidant activity of vegetable drugs and also studied the free radical scavenger activities by means of spectrophotometry (H-donor activity, reducing capability, chelat formation) and chemiluminometry. To prove the free radical scavenging effect of the extracts, the reduced intensity of the H2O2/.OH-isoluminol, microperoxidase system was studied in vitro. The highest correlation was found between the chemical property and the antioxidant effect of the flavonoid rich samples. At the same time it was also observed that the essential oil plays a significant role in the scavenging effect as well. More experiments are in progress to study the most promising compounds in the vegetative and generative organs of parsley.

  14. Investigating the effect of emotional intelligence education on baccalaureate nursing students' emotional intelligence scores.

    PubMed

    Orak, Roohangiz Jamshidi; Farahani, Mansoureh Ashghali; Kelishami, Fatemeh Ghofrani; Seyedfatemi, Naima; Banihashemi, Sara; Havaei, Farinaz

    2016-09-01

    Nursing students, particularly at the time of entering clinical education, experience a great deal of stress and emotion typically related to their educational and clinical competence. Emotional intelligence is known to be one of the required skills to effectively cope with such feelings. The aim of this study was to investigate the effect of training on first-year nursing students' levels of emotional intelligence. This was a quasi-experiment study in which 69 first-year nursing students affiliated with Tehran University of Medical Sciences were assigned to either the control or the experimental groups. The study intervention included of an emotional intelligence educational program offered in eight two-hour sessions for eight subsequent weeks. In total, 66 students completed the study. The study groups did not differ significantly in terms of emotional intelligence scores before and after educational program. Although the educational program did not have an effect on students' emotional intelligence scores, this study finding can be explained. Limited time for exercising the acquired knowledge and skills may explain the non-significant findings. Moreover, our participants were exclusively first-year students who had no clinical experience and hence, might have felt no real need to learn emotional intelligence skills.

  15. 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.

  16. Microfluidic investigation of the effects of oxidative stress on mechanotransduction in red blood cells

    NASA Astrophysics Data System (ADS)

    Zeng, N. F.; Ristenpart, W. D.

    2011-11-01

    Recent work has suggested that RBCs are able to sense and respond to small changes in their environment through post translational modifications (PTMs) in membrane proteins. Because oxidative stress is an important driving force to induce PTMs, the effects of oxidative stress on membrane deformability, lipid peroxidation, and cytoskeletal/hemoglobin crosslinking have been studied extensively. However, experimental work to date on the effects of oxidative stress on RBC mechanotransduction has been limited to applied forces dissimilar to those experienced by RBCs in vivo. Here we investigate the dynamics of shear-induced mechanotransduction in RBCs subjected to varying degrees of oxidative stress by using hydrogen peroxide as a generator of oxidizing radicals. We use a microfluidic platform to impose precisely defined fluid flows that mimic in vivo conditions. The RBCs are visualized passing through a narrow constriction using high speed video at 15,000 frames per second, and quantitative hematological information including cell elongation, rotation and velocity are extracted via custom image analysis algorithms. We demonstrate that oxidative stress significantly alters the dynamic behavior of the RBCs under flow conditions, and we discuss the implications for the consequent effects on mechanotransductive vasodilatory signaling.

  17. 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

  18. Investigating the effectiveness of St John's wort herb as an antimicrobial agent against mycobacteria.

    PubMed

    Mortensen, Trent; Shen, Shujie; Shen, Fenann; Walsh, Marie K; Sims, Ronald C; Miller, Charles D

    2012-09-01

    A persistent need exists for effective treatment agents for mycobacterial infections. This research investigated the effectiveness of the Hypericum perforatum herb (commonly known as St John's wort; SJW) in its growth inhibition of mycobacteria. A SJW extract was effective at inhibiting five nonpathogenic Mycobacterium isolates and Bacillus subtilis, but not Escherichia coli. Quantitative studies of concentration sensitivity to the SJW extract were performed with minimal bactericidal concentrations (MBC) ranging from 0.33 to 2.66 mg extract/mL. The SJW compounds hyperforin (Hfn), hypericin (Hpn), and pseudohypericin (Phn) were quantified in the extract using HPLC. The SJW extract solution of 133 mg extract/mL used in this study contained 2.3 mg Hfn/mL, 0.8 mg Hpn/mL, and 2.1 mg Phn/mL. Purified Hfn, Hpn, and Phn were tested for inhibitory activity against Mycobacterium JLS (M. JLS) at similar concentrations used in the crude extract. While Hfn was inhibitory at 46 µg/mL, none of the purified SJW constituents were bactericidal at concentrations corresponding to SJW treatments. Scanning electron microscopy (SEM) analysis of SJW-treated M. JLS cells showed changes in cell surface morphology.

  19. 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.

  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.

  1. Investigations of interhydrogen bond dynamical coupling effects in the polarized IR spectra of acetanilide crystals.

    PubMed

    Flakus, Henryk T; Michta, Anna

    2010-02-04

    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.

  2. 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.

  3. 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.

  4. Effects of the investigation scale on pumping test results in heterogeneous porous aquifers

    NASA Astrophysics Data System (ADS)

    Schad, Hermann; Teutsch, Georg

    1994-07-01

    At the environmental field site Horkheimer Insel numerous pumping tests were performed at different investigation scales. The measured time-drawdown curves exhibit a characteristic segmentation into two or three drawdown phases. Since the site is highly heterogeneous it was intended to take advantage of the non-stationarity of the flow field during pumping tests in order to determine the effective length scale of the subsurface heterogeneity structure. The time-drawdown curves were evaluated using the Theis' analytical solution, which, however, yields different aquifer parameters for the different drawdown phases. Because this solution does not satisfy the properties of the test site aquifer totally, some of the inferred parameter distributions are regarded as suitable only for a relative comparison rather than representing 'true' effective parameters. Based on a definition of spatial and temporal scale, a statistical description along with a qualitative interpretation of the parameter distributions determined is provided. The results indicate that the effective length scale of the heterogeneity structure can be estimated from pumping test data. However, it is believed that for a quantitative interpretation of the field data, the application of numerical methods is necessary.

  5. 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.

  6. 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.

  7. An investigation of wall effects in microwave-assisted ring-closing metathesis and cyclotrimerization reactions.

    PubMed

    Dallinger, Doris; Irfan, Muhammed; Suljanovic, Amra; Kappe, C Oliver

    2010-08-06

    Challenging Ru-catalyzed ring-closing metathesis transformations leading to eight-membered-ring systems and Ni- or Co-catalyzed [2+2+2] cyclotrimerizations were evaluated at elevated temperatures applying microwave dielectric heating or conventional thermal heating in order to investigate the role of wall effects. All reactions were conducted in a dedicated reactor setup that allowed accurate internal reaction temperature measurements using fiber-optic probes for both types of heating modes. For ring-closing metathesis best results were achieved using an open vessel-gas sparging protocol in 1,2-dichloroethane at reflux temperature (83 degrees C), while cyclotrimerizations were performed under sealed vessel conditions in toluene between 80 and 160 degrees C. For all studied transformations the results achieved in a single-mode microwave reactor could be reproduced by conventional heating in an oil bath by carefully matching the temperature profiles as close as possible during the entire heating and cooling cycle. In contrast to previous literature reports, no evidence that direct in-core microwave heating can increase catalyst lifetime by minimization or elimination of wall effects was obtained. At the same time, no indication for the involvement of nonthermal microwave effects in these homogeneous transition metal-catalyzed transformations was seen.

  8. Effect of deltamethrin (pyrethroid insecticide) on two clones of Daphnia magna (Crustacea, Cladocera): a proteomic investigation.

    PubMed

    Toumi, Héla; Boumaiza, Moncef; Immel, Françoise; Sohm, Bénédicte; Felten, Vincent; Férard, Jean-François

    2014-03-01

    Deltamethrin is a class II pyrethroid insecticide commonly used in agriculture. It is hazardous to freshwater ecosystems, especially for the cladoceran Daphnia magna (Straus 1820). The results of our previous studies based on acute and chronic ecotoxicity experiments revealed differences in the sensitivity between two different clones. In this work, to investigate deltamethrin toxicity mechanisms in two clones of D. magna, we used a proteomic approach in order to analyze changes in protein expression profiles after 48 h of exposure. We detected 1339 spots; then applying statistical criteria (ANOVA p<0.001 and minimum fold change 1.5), only 128 spots were significantly different in the normalized volume. Among the preselected proteins there were 88 up-regulated and 40 down-regulated proteins. Results showed differences in sensitivities after deltamethrin exposure between the clones. Moreover, using the 2-DIGE method, proteomic investigation for deltamethrin exposure proved to be a reliable and powerful approach to investigate effects of deltamethrin as part of research for new metabolic and cellular biomarkers. After identification by mass spectrometry, there were 39 proteins recognized and identified, in which 21 and 18 were up- and down-regulated, respectively, in deltamethrin-exposed clone A compared to three other conditions (controls of each clone and deltamethrin-exposed clone 2). Up- and down-regulated proteins belonged to 12 biological processes (i.e. metabolic processes, apoptosis and stimulus response) and 5 molecular functions (i.e. catalytic activity, binding, structural molecular activity, antioxidant and receptor activities). Identification of these deregulated proteins opens a new way in discovering new molecular targets and putative biomarkers in daphnids exposed to deltamethrin.

  9. Thermodynamic Effect of Platinum Addition to beta-NiAl: An Initial Investigation

    NASA Technical Reports Server (NTRS)

    2005-01-01

    An initial investigation was conducted to determine the effect of platinum addition on the activities of aluminum and nickel in beta-NiAl(Pt) over the temperature range 1354 to 1692 K. These measurements were made with a multiple effusion-cell configured mass spectrometer (multi-cell KEMS). The results of this study show that Pt additions act to decreased alpha(Al) and increased the alpha(Ni) in beta-NiAl(Pt) for constant X(sub Ni)/X(sub Al) approx. = 1.13, while at constant X(sub Al) the affect of Pt on Al is greatly reduced. The measured partial enthalpies of mixing indicate Al-atoms have a strong self interaction while Ni- and Pt-atoms in have similar interactions with Al-atoms. Conversely the binding of Ni-atoms in beta-NiAl decreases with Pt addition independent of Al concentration. These initial results prove the technique can be applied to the Ni-Al-Pt system but more activity measurements are required to fully understand the thermodynamics of this system and how Pt additions improved the scaling behavior of nickel-based superalloys. In addition, with the choice of a suitable oxide material for the effusion-cell, the "closed" isothermal nature of the effusion-cell allows the direct investigation of an alloy-oxide equilibrium which resembles the "local-equilibrium" description of the metal-scale interface observed during high temperature oxidation. It is proposed that with an Al(l) + Al2O3(s) experimental reference state together with the route measurement of the relative partial-pressures of Al(g) and Al2O(g) allows the activities of O and Al2O3 to be determined along with the activities of Ni and Al. These measurements provide a direct method of investigating the thermodynamics of the metal-scale interface of a TGO-scale.

  10. An investigation into the effect of amphiphilic siloxane oligomers on dermal fibroblasts.

    PubMed

    Farrugia, Brooke L; Keddie, Daniel J; George, Graeme A; Lynam, Emily C; Brook, Michael A; Upton, Zee; Dargaville, Tim R

    2012-07-01

    This study investigates the effect of well-defined poly(dimethylsiloxane)-poly(ethylene glycol) (PDMS-PEG) ABA linear block co-oligomers on the proliferation of human dermal fibroblasts. The co-oligomers assessed ranged in molecular weight (MW) from 1335 to 5208 Da and hydrophilic-lipophilic balance (HLB) from 5.9 to 16.6 by varying the number of both PDMS and PEG units. In general, it was found that co-oligomers of low MW or intermediate hydrophilicity significantly reduced fibroblast proliferation. A linear relationship between down-regulation of fibroblast proliferation, and the ratio HLB/MW was observed at concentrations of 0.1 and 1.0 wt % of the oligomers. This enabled the structures with highest efficiency to be determined. These results suggest the possible use of the PEG-PDMS-PEG block co-oligomers as an alternative to silicone gels for hypertrophic scar remediation.

  11. Effects of chewing gum on stress and health: a replication and investigation of dose-response.

    PubMed

    Smith, Andrew

    2013-04-01

    Research suggests that chewing gum may be associated with reduced stress, depression and a reduced likelihood of having high cholesterol and blood pressure. The present study aimed to replicate these findings and extend them by examining dose-response. A web-based survey was completed by a sample of 388 workers from public sector organisations (68.5% female; mean age: 42 years, range 17-64 years). The results showed that chewing gum was associated in a linear dose-response manner with lower levels of perceived stress (both at work and life in general), anxiety and depression. Occasional gum chewers also reported a reduced risk of high cholesterol and blood pressure. Intervention studies are now required to extend these findings, and the mechanisms underlying the effects reported here need further investigation.

  12. Investigation of network tree technology as a tool for developing effective fault isolation procedures

    NASA Astrophysics Data System (ADS)

    Peterson, D. E.

    The use of the Sneak Circuit Analysis (SCA) for effective fault isolation procedure development is investigated, resulting in the definition of a structured methodology for creating logic trees with development and evaluation applications. A systems point-to-point electrical continuity is encoded in a card-image format in order to accomplish data entry, which should be performed via an interactive system. The sorting process should be as batch a process as possible, and the resulting groups are plotted in forest and network tree form. These trees are then used to determine normal and abnormal system response. Finally, the fault isolation procedure logic is developed. It is noted that the resulting methodology can be used for verification purposes, and for other systems analyses.

  13. 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.

  14. A clinical investigation of the effects of omission of pumice prophylaxis on band and bond failure.

    PubMed

    Barry, G R

    1995-08-01

    One hundred and twelve first molar bands and 614 directly bonded brackets on incisor, canine, and premolar teeth were included in a clinical trail to investigate the importance of omission of pumice prophylaxis at the time of banding and bonding, on their possible subsequent failure. Half of the sample were selected for the non-pumiced test groups using a random number allocation method, the remaining pumiced teeth acting as control groups. Two etch times were used for the direct bonding part of the study, 15 and 60 seconds, with non-pumiced test and pumiced control groups included within both etch-time groups. Results showed no statistical difference in the failure rate of attachments in either test or control groups during the course of treatment. The different etch times had no significant effects in the direct bonding part of the study.

  15. Investigation of the effects of electron plasma frequency on the operation of a helix TWT

    NASA Astrophysics Data System (ADS)

    Oksuz, Lutfi; Haytural, Necati; Uygun, Emre; Bozduman, Ferhat; Yesiltepe, Hakan; Gulec, Ali

    2016-10-01

    The oscillations of electrons are an important subject for the design procedure of linear beam tubes such as klystrons and TWTs. These oscillation frequencies may be affected by the finite region of the tube if the plasma wavelength of the electrons are larger than the bounding region of the device, leading to a reduced plasma frequency which further leads to an increase in wavelength. Following the Pierce's theory on traveling wave tubes, it is seen that the reduced plasma frequency takes place in space charge terms which also include the Pierce's gain parameter C. In this study the effects of plasma frequency on the operation of a helix TWT are investigated using CST Particle Studio. This project is supported by TUBITAK with project number: 1140075.

  16. Investigation of electromagnetic backscattering from nearshore sea surfaces modulated by shoaling effect

    NASA Astrophysics Data System (ADS)

    Nie, D.; Zhang, M.; Li, J.

    2016-10-01

    The electromagnetic (EM) scattering features of radar scattered echoes from nearshore sea surfaces are investigated using the second-order small-slope approximation (SSA-II). The joint influences of wind fetch and water depth on the normalized radar cross section (NRCS) of and Doppler spectra for echoes from nearshore sea surfaces are mainly studied. The numerical results show that with a further increasing fetch, the excess of NRCS for small depth sea over that for deeper sea increases, and Doppler spectral features are also intensely influenced by nonlinear interactions between waves in the large wind fetch and small water depth marine environment. These both indicate that the effects of the finite depth are more prominent with increasing wind fetch, especially for HH polarization.

  17. 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.

  18. Investigation on grain size effect in high strain rate ductility of 1100 pure aluminum

    NASA Astrophysics Data System (ADS)

    Bonora, N.; Bourne, N.; Ruggiero, A.; Iannitti, G.; Testa, G.

    2017-01-01

    The effect of the initial grain size on the material ductility at high strain rates in 1100 pure aluminum was investigated. Dynamic tensile extrusion (DTE) tests, at different impact velocities, were performed. Samples have been annealed at 350°C for different exposure times to induce grain growth. Extruded fragments were soft-recovered and the overall length of the extruded jets was used as a measure of material ductility at high strain rates. Numerical simulation of DTE test at different velocity was performed using the modified Rusinek-Klepaczko constitutive model. Results indicates that, as reported for pure copper, the overall ductility of the aluminum increases when grain size decreases. Numerical simulation results were in quite good agreement with experimental data.

  19. Computer-controlled system for investigating the hydrostatic piezoresistive effect as a function of temperature

    NASA Astrophysics Data System (ADS)

    Amin, Ahmed

    1987-08-01

    A system has been developed for investigating the piezoresistive effect in semiconducting solids and conductive polymers under different elastic and thermal boundary conditions. The system provides the necessary information needed for sensor design such as nonlinearity, hysteresis, and temperature dependence of the piezoresistance coefficient. The system operates under full computer control for both data acquisition and data reduction cycles. The temperature dependence of the hydrostatic piezoresistance coefficient of a donor-doped polycrystalline semiconducting barium titanate below and above its ferroelectric-paraelectric Curie point will be presented for the first time. The nonlinear and hysteretic behavior of an electrically conductive polymer over the pressure range of 0-30 MPa will also be demonstrated.

  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. Investigating the Effect of Cold Soak Duration on Phenolic Extraction during Cabernet Sauvignon Fermentation.

    PubMed

    Panprivech, Siriwan; Lerno, Larry A; Brenneman, Charles A; Block, David E; Oberholster, Anita

    2015-05-04

    The impact of increasing cold soak (CS) duration (0, 1, 4, 7, and 10 days at 10 °C) on the extraction of phenolic compounds during the CS period and primary fermentation as well as the final composition of Cabernet Sauvignon wine was investigated. The results showed that CS duration had no effect on hydroxycinnamate and flavonol extractions. Greater amounts of gallic acid, (+)-catechin, (-)-epicatechin, and total tannins were extracted with increasing CS duration, with differences maintained during bottle aging. Anthocyanin extraction and color density increased with longer periods of CS; however, by the end of primary fermentation, as well as three months' bottle aging, there were no significant differences due to CS duration. The wines made with seven and 10 days of CS had higher seed tannin contributions and total tannin compared to the non-CS wine, which could potentially result in increased astringency.

  2. 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.

  3. 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.

  4. Theoretical and experimental investigation of fluid rheology effects on modulated ultrasound propagation.

    PubMed

    Özkök, Okan; Uludag, Yusuf

    2014-09-01

    A mathematical model is developed and presented to capture the effect of viscoelastic nature of a material on modulated ultrasound (US) pulses. The model is established by considering perturbation of material elements subject to modulated US pulses and by introducing the exponential relaxation of the perturbed fluid elements with a spectrum of time constants. Both the model and experimental findings revealed that consecutive perturbation of a material via the modulated US pulses enabled to probe the relaxation times of similar order of magnitudes to the frequency of the US modulation while filtering out the impact of other relaxation times on the US measurement. The US experimental results were verified by those of a conventional rheometer. Hence carrying out measurements at different US modulation frequencies in the Hz ranges seems to allow one to obtain the relaxation time spectrum of the investigated material in the time scales of milliseconds to seconds.

  5. 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.

  6. Investigations of bisacodyl with modified β-cyclodextrins: Characterization, molecular modeling, and effect of PEG.

    PubMed

    Li, Shanshan; Wang, Lili; Jiang, Jian; Tang, Peixiao; Wang, Qing; Wu, Di; Li, Hui

    2015-12-10

    Bisacodyl inclusion into hydroxypropyl-β-cyclodextrin and 2,6-di-O-methyl-β-cyclodextrin cavities was experimentally and theoretically investigated, and the effect of PEG 4000 on these inclusions was studied. Isothermal calorimetry titration curves indicated that the binary inclusion processes are enthalpy- and entropy-driven. The solid-state complexes were fully characterized by FT-IR, XRPD, DSC and SEM analyses. FT-IR, (1)H NMR, and ROESY studies provided the most favorable encapsulation modes of binary complexes, and results were further confirmed by molecular docking and molecular dynamics studies. The presence of PEG 4000 slightly enhanced encapsulation efficiency, solubility and dissolution rates of the binary complexes. In vivo studies showed that complexes with CDs markedly accelerated gastrointestinal transit time compared with pure bisacodyl, whereas addition of PEG 4000 showed no further significant improvement of the bioavailability.

  7. 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

  8. Experimental investigation of the effect of multimodal inclined interface on Richtmyer-Meshkov instability evolution

    NASA Astrophysics Data System (ADS)

    Mohaghar, Mohammad; Carter, John; Musci, Benjamin; Ranjan, Devesh

    2016-11-01

    In the Georgia Tech Shock Tube and Advanced Mixing Laboratory, the evolution of Richtmyer-Meshkov instability (RMI) which arises from two initial conditions, namely, a predominantly single mode, inclined interface between two gases, and a perturbed, multimodal, inclined interface are studied. The gas combination of nitrogen-acetone as light gas and carbon dioxide as heavy gas (Atwood number of 0.23) with an inclination angle of 80 degrees (η/ λ = 0.097) was chosen in this set of experiments. The interface is visualized using planar laser diagnostics (simultaneous PLIF/PIV measurements), once impulsively accelerated by a Mach 1.55. The ensemble-averaged turbulence measurements of the density, velocity and density-velocity cross-statistics are used to investigate the effects of added secondary modes to the interface on the correlation between turbulence and mixing quantities.

  9. 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.

  10. 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.

  11. Isotope effects in water as investigated by neutron diffraction and path integral molecular dynamics

    NASA Astrophysics Data System (ADS)

    Zeidler, Anita; Salmon, Philip S.; Fischer, Henry E.; Neuefeind, Jörg C.; Simonson, J. Mike; Markland, Thomas E.

    2012-07-01

    The structures of heavy and light water at 300 K were investigated by using a joint approach in which the method of neutron diffraction with oxygen isotope substitution was complemented by path integral molecular dynamics simulations. The diffraction results, which give intra-molecular O-D and O-H bond distances of 0.985(5) and 0.990(5) Å, were found to be in best agreement with those obtained by using the flexible anharmonic TTM3-F water model. Both techniques show a difference of ≃ 0.5% between the O-D and O-H intra-molecular bond lengths, and the results support a competing quantum effects model for water in which its structural and dynamical properties are governed by an offset between intra-molecular and inter-molecular quantum contributions. Further consideration of the O-O correlations is needed in order to improve agreement with experiment.

  12. Computational Investigations on the Effects of Gurney Flap on Airfoil Aerodynamics

    PubMed Central

    Jain, Shubham; Sitaram, Nekkanti; Krishnaswamy, Sriram

    2015-01-01

    The present study comprises steady state, two-dimensional computational investigations performed on NACA 0012 airfoil to analyze the effect of Gurney flap (GF) on airfoil aerodynamics using k-ε RNG turbulence model of FLUENT. Airfoil with GF is analyzed for six different heights from 0.5% to 4% of the chord length, seven positions from 0% to 20% of the chord length from the trailing edge, and seven mounting angles from 30° to 120° with the chord. Computed values of lift and drag coefficients with angle of attack are compared with experimental values and good agreement is found at low angles of attack. In addition static pressure distribution on the airfoil surface and pathlines and turbulence intensities near the trailing edge are present. From the computational investigation, it is recommended that Gurney flaps with a height of 1.5% chord be installed perpendicular to chord and as close to the trailing edge as possible to obtain maximum lift enhancement with minimum drag penalty. PMID:27347517

  13. Investigating the extrinsic size effect of palladium and gold spherical nanoparticles

    NASA Astrophysics Data System (ADS)

    Rashidian Vaziri, M. R.; Omidvar, A.; Jaleh, B.; Partovi Shabestari, N.

    2017-02-01

    In many optical applications, knowing the variations of the plasmonic resonance wavelengths of a special kind of nanoparticles in terms of their size before the experiment began, can assist the users in selection of an appropriate preparation method for the optimum functionality. In this work, in order to show the role of the preparation method on the mean size and the size distribution of nanoparticles, two different chemical bottom-up and physical top-down methods were used for the synthesis of palladium and gold nanoparticles. Chemical reduction of metal salt and laser ablation in liquid media methods were respectively used for preparation of palladium and gold nanoparticles. It is shown that the chemical bottom-up method results in the formation of smaller particles with narrower size distribution. Optical properties and plasmonic resonance absorption of the prepared nanoparticles were investigated by UV-vis spectroscopy and their size distribution were determined by transmission electron microscopy (TEM) images. Using the measured size distribution of nanoparticles, their optical extinctions are modelled using the Mie theory of scattering. A comprehensive study on the extrinsic size effect of palladium and gold nanoparticles is performed and the dipolar and the quadrupolar Mie resonances in these nanoparticles are investigated in details. The reported results can be used for selecting the preparation method of these nanoparticles and for choosing the appropriate laser wavelength to excite stronger or weaker Mie resonances for specific applications.

  14. Observation and experimental investigation of confinement effects on ion transport and electrokinetic flows at the microscale

    PubMed Central

    Benneker, Anne M.; Wood, Jeffery A.; Tsai, Peichun A.; Lammertink, Rob G. H.

    2016-01-01

    Electrokinetic effects adjacent to charge-selective interfaces (CSI) have been experimentally investigated in microfluidic platforms in order to gain understanding on underlying phenomena of ion transport at elevated applied voltages. We experimentally investigate the influence of geometry and multiple array densities of the CSI on concentration and flow profiles in a microfluidic set-up using nanochannels as the CSI. Particle tracking obtained under chronoamperometric measurements show the development of vortices in the microchannel adjacent to the nanochannels. We found that the direction of the electric field and the potential drop inside the microchannel has a large influence on the ion transport through the interface, for example by inducing immediate wall electroosmotic flow. In microfluidic devices, the electric field may not be directed normal to the interface, which can result in an inefficient use of the CSI. Multiple vortices are observed adjacent to the CSI, growing in size and velocity as a function of time and dependent on their location in the microfluidic device. Local velocities inside the vortices are measured to be more than 1.5 mm/s. Vortex speed, as well as flow speed in the channel, are dependent on the geometry of the CSI and the distance from the electrode. PMID:27853257

  15. Borehole Investigation of the Effectiveness of Grout Injection Technology on Coal Mine Subsidence Control

    NASA Astrophysics Data System (ADS)

    Xuan, Dayang; Xu, Jialin; Wang, Binglong; Teng, Hao

    2015-11-01

    Grout injection into the horizontal fracture at the bed separation of an overburden is used as a surface subsidence control measure in coal-producing countries such as Poland, China, and Australia. However, the stiffness and distribution of the grouting mass in the post-injected overburden, as well as its effect on surface subsidence control, have not been investigated. To address these issues, two surface boreholes were drilled into the post-injected overburden above a longwall panel on the study site. It was found that the fly ash injected more than 7 months previously had become compacted. More than 90 % of the total fill was concentrated in the main injection section (MIS) of the overburden (thickness of 4.8-18.4 m). The MIS was located between the bottom of the injection borehole and the key stratum immediately above. Following injection, the central gob area received the maximum possible compression and served as the foundation of the support for the grout, allowing the grout to restrain the deformation of the strata above it, thus reducing surface subsidence. The results of this investigation may facilitate future injection design, thus improving the control of surface subsidence.

  16. Computational Investigations on the Effects of Gurney Flap on Airfoil Aerodynamics.

    PubMed

    Jain, Shubham; Sitaram, Nekkanti; Krishnaswamy, Sriram

    2015-01-01

    The present study comprises steady state, two-dimensional computational investigations performed on NACA 0012 airfoil to analyze the effect of Gurney flap (GF) on airfoil aerodynamics using k-ε RNG turbulence model of FLUENT. Airfoil with GF is analyzed for six different heights from 0.5% to 4% of the chord length, seven positions from 0% to 20% of the chord length from the trailing edge, and seven mounting angles from 30° to 120° with the chord. Computed values of lift and drag coefficients with angle of attack are compared with experimental values and good agreement is found at low angles of attack. In addition static pressure distribution on the airfoil surface and pathlines and turbulence intensities near the trailing edge are present. From the computational investigation, it is recommended that Gurney flaps with a height of 1.5% chord be installed perpendicular to chord and as close to the trailing edge as possible to obtain maximum lift enhancement with minimum drag penalty.

  17. Investigation of the dimensionality of charge transport in organic field effect transistors

    NASA Astrophysics Data System (ADS)

    Abdalla, Hassan; Fabiano, Simone; Kemerink, Martijn

    2017-02-01

    Ever since the first experimental investigations of organic field effect transistors (OFETs) the dimensionality of charge transport has alternately been described as two dimensional (2D) and three dimensional (3D). More recently, researchers have turned to an analytical analysis of the temperature-dependent transfer characteristics to classify the dimensionality as either 2D or 3D as well as to determine the disorder of the system, thereby greatly simplifying dimensionality investigations. We applied said analytical analysis to the experimental results of our OFETs comprising molecularly well-defined polymeric layers as the active material as well as to results obtained from kinetic Monte Carlo simulations and found that it was not able to correctly distinguish between 2D and 3D transports or give meaningful values for the disorder and should only be used for quasiquantitative and comparative analysis. We conclude to show that the dimensionality of charge transport in OFETs is a function of the interplay between transistor physics and morphology of the organic material.

  18. Numerical and experimental investigation of light trapping effect of nanostructured diatom frustules

    PubMed Central

    Chen, Xiangfan; Wang, Chen; Baker, Evan; Sun, Cheng

    2015-01-01

    Recent advances in nanophotonic light-trapping technologies offer promising solutions in developing high-efficiency thin-film solar cells. However, the cost-effective scalable manufacturing of those rationally designed nanophotonic structures remains a critical challenge. In contrast, diatoms, the most common type of phytoplankton found in nature, may offer a very attractive solution. Diatoms exhibit high solar energy harvesting efficiency due to their frustules (i.e., hard porous cell wall made of silica) possessing remarkable hierarchical micro-/nano-scaled features optimized for the photosynthetic process through millions of years of evolution. Here we report numerical and experimental studies to investigate the light-trapping characteristic of diatom frustule. Rigorous coupled wave analysis (RCWA) and finite-difference time-domain (FDTD) methods are employed to investigate the light-trapping characteristics of the diatom frustules. In simulation, placing the diatom frustules on the surface of the light-absorption materials is found to strongly enhance the optical absorption over the visible spectrum. The absorption spectra are also measured experimentally and the results are in good agreement with numerical simulations. PMID:26155924

  19. Investigation of the effect of contrails on global irradiance and solar energy production

    NASA Astrophysics Data System (ADS)

    Weihs, Philipp; Rennhofer, Marcus; Baumgartner, Dietmar; Wagner, Jochen; Laube, Wolfgang; Gadermaier, Josef

    2013-04-01

    In the present study we investigate the effect of contrails on global shortwave radiation and on Photovoltaic module performance. This investigation is performed using continuous hemispherical fish eye photographs of the sky, diffuse and direct shortwave measurements and short circuit current measurements of a-Si, c-Si and CdTe PV modules. These measurements have been performed at the solar observatory Kanzelhöhe (1540 m.a.s.l) located in the southern part of Austria during a period of one and half year. The time resolution of the measurements is one minute, which allows to accurately follow the formation-eventually the disappearance- or the movement of the contrails in the sky. Using the fish eye photographs we identified clear sky days with a high contrail persistence. We especially look at situations where the contrails were shading the sun. Results show that contrails shading the sun may reduce the global radiation by up to 60%. In general we however observe that during days with a high contrail persistence the diffuse irradiance is slightly increased. Finally a statistic of the contrail persistence during the period of measurement is presented and conclusions as to the relevance for the solar energy production are drawn.

  20. Investigation of the effects of concomitant caffeine administration on the metabolic disposition of pyrazinamide in rats.

    PubMed

    Mehmedagic, Aida; Verite, Philippe; Menager, Sabine; Tharasse, Christine; Chabenat, Christiane; Andre, Dominique; Lafont, Olivier

    2002-07-01

    The utility of pyrazinamide (PZA) in the short-course antituberculous treatment is well established. All available data support the idea that the PZA metabolite pyrazinoic acid (PA) is the active compound against M. tuberculosis. This situation warranted a deeper investigation of possible interactions with respect to its metabolic disposition. Caffeine, which is widely used as a drug and is a common constituent of most diets, shares with PZA the same metabolic enzyme, xanthine oxidase (XO). This study investigated if, and in what manner, concomitant administration of caffeine affects PZA metabolism. PZA and caffeine, in various doses (PZA=50 or 100 mg kg(-1) and caffeine= 0, 50, 100, and 150 mg kg(-1)), were administered to female Sprague-Dawley rats. PZA and its three main metabolites were quantified in 24 h urine samples by reversed phase-HPLC Concomitant administration of 100 mg kg(-1) caffeine and 50 mg kg(-1) PZA increased from the excretion (p<0.05) of the most water-soluble and the least toxic PZA metabolite 5-hydroxypyrazinoic acid (5-OH-PA) from 66.18+/-10.87 to 94.56+/-8.65 micromol/24 h. This effect was more pronounced when 100 mg kg(-1) of PZA was administered increasing excretion of 5-OH-PA from 113.28+/-70 to 173.23+/-17.82 micromol/24 h. These results show that the metabolic disposition of PZA is affected by concomitant caffeine intake.

  1. Investigation of temporal contrast effects in femtosecond pulse laser micromachining of metals.

    SciTech Connect

    Campbell, Benjamin (Pennsylvania State University, Freeport, PA); Palmer, Jeremy Andrew

    2006-06-01

    Femtosecond pulse laser drilling has evolved to become a preferred process for selective (maskless) micromachining in a variety of materials, including metals, polymers, semiconductors, ceramics, and living tissue. Manufacturers of state-of-the-art femtosecond laser systems advertise the inherent advantage of micromachining with ultra short pulses: the absence of a heat affected zone. In the ideal case, this leads to micro and nano scale features without distortion due to melt or recast. However, recent studies have shown that this is limited to the low fluence regime in many cases. High dynamic range autocorrelation studies were performed on two commercial Ti:sapphire femtosecond laser systems to investigate the possible presence of a nanosecond pedestal in the femtosecond pulse produced by chirped pulse amplification. If confirmed, nanosecond temporal phenomena may explain many of the thermal effects witnessed in high fluence micromachining. The material removal rate was measured in addition to feature morphology observations for percussion micro drilling of metal substrates in vacuum and ambient environments. Trials were repeated with proposed corrective optics installed, including a variable aperture and a nonlinear frequency doubling crystal. Results were compared. Although the investigation of nanosecond temporal phenomena is ongoing, early results have confirmed published accounts of higher removal rates in a vacuum environment.

  2. Investigation on the effect of exposure time on scintillator afterglow for ultra-fast tomography acquisition

    NASA Astrophysics Data System (ADS)

    Zefreh, K. Z.; Welford, F. M.; Sijbers, Jan

    2016-12-01

    Thanks to the ultra-fast endstation of the TOMCAT beamline, it is possible to do a tomographic scan with a sub-second temporal resolution which allows following dynamic processes in 4D (3D space + time). This ultra- high-rate tomography acquisition, exploiting the distinctive peculiarities of synchrotron radiation, provides nondestructive investigation of many dynamic processes which were not possible in the past. For example a continuous tensile test has been conducted recently in-situ for the first time with a frequency of 20 tomograms per second (20 Hz acquisition frequency). In the ultra-fast endstation a scintillator is used to convert X-ray to visible photons that can be detected by the camera. However, this conversion is not ideal and the scintillator response decays exponentially with afterglow. Afterglow can cause resolution degradation and artifacts (such as ring and band) especially with high rotation speed. On the other hand, to achieve a higher scan speed, thicker scintillators are more common because they result in higher emission intensities that can compensate the short exposure time in fast scans. However, the resolution deteriorates as the scintillator's thickness increases and thicker scintillators show higher afterglow. Performing many ultra-fast scans at the TOMCAT beamline with different acquisition rate, we demonstrate how the exposure time effects on the projection data and reconstructed images. Using two different thicknesses of LAG scintillator we also investigate the afterglow artifacts for different acquisition rate and exposure time.

  3. Numerical and experimental investigation of light trapping effect of nanostructured diatom frustules

    NASA Astrophysics Data System (ADS)

    Chen, Xiangfan; Wang, Chen; Baker, Evan; Sun, Cheng

    2015-07-01

    Recent advances in nanophotonic light-trapping technologies offer promising solutions in developing high-efficiency thin-film solar cells. However, the cost-effective scalable manufacturing of those rationally designed nanophotonic structures remains a critical challenge. In contrast, diatoms, the most common type of phytoplankton found in nature, may offer a very attractive solution. Diatoms exhibit high solar energy harvesting efficiency due to their frustules (i.e., hard porous cell wall made of silica) possessing remarkable hierarchical micro-/nano-scaled features optimized for the photosynthetic process through millions of years of evolution. Here we report numerical and experimental studies to investigate the light-trapping characteristic of diatom frustule. Rigorous coupled wave analysis (RCWA) and finite-difference time-domain (FDTD) methods are employed to investigate the light-trapping characteristics of the diatom frustules. In simulation, placing the diatom frustules on the surface of the light-absorption materials is found to strongly enhance the optical absorption over the visible spectrum. The absorption spectra are also measured experimentally and the results are in good agreement with numerical simulations.

  4. Flight investigation of the effect of tail boom strakes on helicopter directional control

    NASA Technical Reports Server (NTRS)

    Kelly, Henry L.; Crowell, Cynthia A.; Yenni, Kenneth R.; Lance, Michael B.

    1993-01-01

    A joint U.S. Army/NASA flight investigation was conducted utilizing a single-rotor helicopter to determine the effectiveness of horizontally mounted tail boom strakes on directional controllability and tail rotor power during low-speed, crosswind operating conditions. Three configurations were investigated: (1) baseline (strakes off), (2) single strake (strake at upper shoulder on port side of boom), and (3) double strake (upper strake plus a lower strake on same side of boom). The strakes were employed as a means to separate airflow over the tail boom and change fuselage yawing moments in a direction to improve the yaw control margin and reduce tail rotor power. Crosswind data were obtained in 5-knot increments of airspeed from 0 to 35 knots and in 30 deg increments of wind azimuth from 0 deg to 330 deg. At the most critical wind azimuth and airspeed in terms of tail rotor power, the strakes improved the pedal margin by 6 percent of total travel and reduced tail rotor power required by 17 percent. The increase in yaw control and reduction in tail rotor power offered by the strakes can expand the helicopter operating envelope in terms of gross weight and altitude capability. The strakes did not affect the flying qualities of the vehicle at airspeeds between 35 and 100 knots.

  5. Investigation of duty cycle effect on corrosion properties of electrodeposited calcium phosphate coatings.

    PubMed

    Azem, Funda Ak; Delice, Tulay Koc; Ungan, Guler; Cakir, Ahmet

    2016-11-01

    The bioceramic calcium phosphate (CaP) is frequently used for improving bone fixation in titanium medical implants and thus increasing lifetime of the implant. It is known that the application of CaP coatings on metallic implant devices offers the possibility of combining the strength of the metals and the bioactivity of the ceramic materials. Many different techniques are available for producing CaP coatings. Electrochemical deposition method is widely used because of its ease of operation parameters, low temperature requirement, reproducibility and suitability for coating complex structures. This technique allows obtaining CaP coatings which promote bone in growth during the first healing period leading to permanent fixation. Electrochemical pulse technique is an alternative to calcium phosphate deposition techniques usually employed to cover orthopedic or dental titanium implant surfaces. Additionally, pulse electrodeposition technique can produce more uniform and denser CaP coatings on metallic implants. In this study, CaP based coatings were produced by electrochemical pulse technique on Ti6Al4V substrates. The resulting CaP deposits were investigated by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Corrosion properties of the CaP coatings were also investigated. The results showed that various duty cycle ranges have remarkably effect on morphology, crystallinity and corrosion properties of the produced CaP coatings.

  6. Investigation of surface topography effects on metal flow under lubricated hot compression of aluminum

    NASA Astrophysics Data System (ADS)

    Kurk, Justin Irvin

    An investigation was conducted to study the effects of die surface topography, specifically surface roughness and lay, on metal flow and the friction factor under lubricated hot compression. 6061-T6 aluminum rings and square bar stock specimens were compressed on H-13 tool steel platens machined with a unidirectional lay pattern to six different roughnesses between a R 0 10 and 240 muin. A lab based hydraulic press mounted with an experimental die set was used for all testing. Repeated trials were conducted using high temperature vegetable oil and boron nitride lubricants. Metal flow was quantified as a function of surface roughness, lay orientation, and die temperature. Approximate plane strain cigar test specimens were compressed at platen temperatures of 300 °F and 400 °F and at orientations of 0°, 45°, and 90° between the longitudinal axis and unidirectional platen surface lay. The friction factor was assessed using the ring compression test under varying platen roughness conditions and die temperatures between 250 °F and 400 °F. Results indicate metal flow is optimized at low platen roughnesses and orientations parallel to the surface lay of the platen. Die temperature was not found to influence metal flow within the temperature range investigated. The friction factor was observed to be minimized at lower die temperatures and platen roughnesses.

  7. EPR investigation of UV light effect on calcium carbonate powders with different grain sizes.

    PubMed

    Kabacińska, Zuzanna; Krzyminiewski, Ryszard; Dobosz, Bernadeta

    2014-06-01

    This study is based on investigation of calcium carbonate powders with different grain sizes exposed to UV light. Calcium carbonate is widely used in many branches of industry, e.g. as a filler for polymer materials; therefore, knowing its properties, among them also its reaction to UV light, is essential. Samples of powdered calcium carbonate with average grain sizes of 69 and 300 nm and 2.1, 6, 16, 25 µm were used in this investigation. Measurements were performed at room temperature using EPR X-band spectrometer, and they have shown the additional signals induced by the light from Hg lamp. The effect of annealing of the micro-grain samples was also studied. The spectra of four micro-grain samples after irradiation are similar, but there are differences between them and the other two powders, which could be related to the different sizes of their grains. Further studies based on these preliminary results may prove useful in research of photodegradation of CaCO3-filled materials, as well as helpful in increasing the accuracy of dating of archaeological and geological objects.

  8. Investigating physical field effects on the size-dependent dynamic behavior of inhomogeneous nanoscale plates

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Farzad; Reza Barati, Mohammad

    2017-02-01

    This article investigates the thermo-mechanical vibration frequencies of magneto-electro-thermo-elastic functionally graded (METE-FG) nanoplates in the framework of refined four-unknown shear deformation plate theory. The present nanoplate is subjected to various kinds of thermal loads with uniform, linear and nonlinear distributions. The nonlinear distribution is considered as heat conduction and sinusoidal temperature rise. The present refined theory captures the influences of shear deformations without the need for shear correction factors. Thermo-magneto-electro-elastic coefficients of the FG nanoplate vary gradually along the thickness according to the power-law form. The scale coefficient is taken into consideration implementing the nonlocal elasticity of Eringen. The governing equations are derived through Hamilton's principle and are solved analytically. The frequency response is compared with those of previously published data. The obtained results are presented for the thermo-mechanical vibrations of the FG nanobeams to investigate the effects of material graduation, nonlocal parameter, mode number, slenderness ratio and thermal loading in detail. The present study is associated to aerospace, mechanical and nuclear engineering structures which are under thermal loads.

  9. Investigation of Aerosol Indirect Effects on Simulated Flash-flood Heavy Rainfall over Korea

    SciTech Connect

    Lim, Kyo-Sun; Hong, Songyou

    2012-11-01

    This study investigates aerosol indirect effects on the development of heavy rainfall near Seoul, South Korea, on 12 July 2006, focusing on precipitation amount. The impact of the aerosol concentration on simulated precipitation is evaluated by varying the initial cloud condensation nuclei (CCN) number concentration in the Weather Research and Forecasting (WRF) Double-Moment 6-class (WDM6) microphysics scheme. The simulations are performed under clean, semi-polluted, and polluted conditions. Detailed analysis of the physical processes that are responsible for surface precipitation, including moisture and cloud microphysical budgets shows enhanced ice-phase processes to be the primary driver of increased surface precipitation under the semi-polluted condition. Under the polluted condition, suppressed autoconversion and the enhanced evaporation of rain cause surface precipitation to decrease. To investigate the role of environmental conditions on precipitation response under different aerosol number concentrations, a set of sensitivity experiments are conducted with a 5 % decrease in relative humidity at the initial time, relative to the base simulations. Results show ice-phase processes having small sensitivity to CCN number concentration, compared with the base simulations. Surface precipitation responds differently to CCN number concentration under the lower humidity initial condition, being greatest under the clean condition, followed by the semi-polluted and polluted conditions.

  10. Effects of spatially heterogeneous porosity on matrix diffusion as investigated by X-ray absorption imaging

    NASA Astrophysics Data System (ADS)

    Tidwell, Vincent C.; Meigs, Lucy C.; Christian-Frear, Tracy; Boney, Craig M.

    2000-03-01

    High-resolution X-ray absorption imaging was used to investigate the effects of spatially heterogeneous porosity on matrix diffusion. Experiments were performed on four, centimeter-scale slabs of Culebra dolomite taken from the Waste Isolation Pilot Plant (WIPP) site. These tests involved the diffusion of potassium iodide into a single edge of each brine-saturated rock slab, while X-ray absorption imaging was used to measure the two-dimensional relative concentration distribution at different times during the experiment. X-ray imaging was also used to measure the heterogeneous, two-dimensional porosity distribution of each rock slab. The resulting high-resolution data provide unique insight into the spatially varying diffusion characteristics of each heterogeneous rock sample, which traditional methods such as through-diffusion experiments cannot. In these tests, significant variations in the diffusion coefficient were calculated over the relatively small length (centimeter) and time scales (months) investigated. Results also indicated that these variations were related to the heterogeneous porosity characteristics of each rock sample. Not only were the diffusion coefficients found to depend on the magnitude of the porosity but also on its spatial distribution. Specifically, the geometry, position, and orientation of the heterogeneous porosity features populating each rock slab appeared to influence the diffusion characteristics.

  11. Investigation of the different base fluid effects on the nanofluids heat transfer and pressure drop

    NASA Astrophysics Data System (ADS)

    Bayat, Javad; Nikseresht, Amir Hossein

    2011-09-01

    A numerical study of laminar forced convective flows of three different nanofluids through a horizontal circular tube with a constant heat flux condition has been performed. The effect of Al2O3 volume concentration 0 ≤ φ ≤ 0.09 in the pure water, water-ethylene glycol mixture and pure ethylene glycol as base fluids, and Reynolds number of 100 ≤ Re ≤ 2,000 for different power inputs in the range of 10 ≤ Q( W) ≤ 400 have been investigated. In this study, all of the nanofluid properties are temperature and nanoparticle volume concentration dependent. The governing equations have been solved using finite volume approach with the SIMPLER algorithm. The results indicate an increase in the averaged heat transfer coefficient with increasing the mass of ethylene glycol in the water base fluid, solid concentration and Reynolds number. From the investigations it can be inferred that, the pressure drop and pumping power in the nanofluids at low solid volumetric concentration (φ < 3%) is approximately the same as in the pure base fluid in the various Reynolds numbers, but the higher solid nanoparticle volume concentration causes a penalty drop in the pressure. Moreover, this study shows it is possible to achieve a higher heat transfer rate with lower wall shear stress with the use of proper nanofluids.

  12. Investigation of effective forensic cleaning methods for bullet and cartridge case samples

    NASA Astrophysics Data System (ADS)

    Shuherk, Cassie Marie

    Bullet and cartridge case evidence may potentially link weapons and crimes through the comparison of toolmark patterns. This analysis relies on the clarity of the toolmarks and the ability of the examiner to identify patterns on the evidence. These patterns may be distorted by debris such as soil, blood, cyanoacrylate, and construction materials. Despite the potential importance of bullet and cartridge case evidence, few investigations of proper cleaning methods have been conducted. The present study was designed to examine the effects of various cleaning solutions and application methods on copper and brass bullets and cartridge cases. Additionally, this research investigated the efficacy of these cleaning protocols on the common evidence contaminants blood and cyanoacrylate. No cleaning method was found to be universally effective on both contaminant types and nondestructive to the metal surface. Ultrasonication was the most efficient application method employed when used in conjunction with an appropriate cleaning solution. Acetone proved to be safe and successful at removing heavy cyanoacrylate deposits from brass cartridge cases without damaging the metal. Although sulfuric acid removed most of the cyanoacrylate from the brass cartridge case, ultrasonication of the fumed cartridge cases in sulfuric acid caused the nickel-plated primer caps to turn black. Additionally, etching occurred when sulfuric acid was allowed to dry on the cartridge case surface. Citric acid, salt-flour-vinegar paste, TergazymeRTM, and water did not effectively remove the cyanoacrylate from the cartridge cases, but the solutions were safe to use on the brass and sometimes resulted in a shinier surface. Regardless of the cleaning method employed, the bloodstained bullets retained most or all of the underlying brown tarnish. Ultrasonication with sulfuric acid was successful at removing some blood-initiated tarnishing; however, the removal of residues was not complete, making it difficult

  13. Investigation of effects of terpene skin penetration enhancers on stability and biological activity of lysozyme.

    PubMed

    Varman, Rahul M; Singh, Somnath

    2012-12-01

    The transport of proteins through skin can be facilitated potentially by using terpenes as chemical enhancers. However, we do not know about the effects of these enhancers on the stability and biological activity of proteins which is crucial for the development of safe and efficient formulations. Therefore, this project investigated the effects of terpene-based skin penetration enhancers which are reported as nontoxic to the skin (e.g., limonene, p-cymene, geraniol, farnesol, eugenol, menthol, terpineol, carveol, carvone, fenchone, and verbenone), on the conformational stability and biological activity of a model protein lysozyme. Terpene (5% v/v) was added to lysozyme solution and kept for 24 h (the time normally a transdermal patch remains) for investigating conformational stability profiles and biological activity. Fourier transform infrared spectrophotometer was used to analyze different secondary structures, e.g., α-helix, β-sheet, β-turn, and random coil. Conformational changes were also monitored by differential scanning calorimeter by determining midpoint transition temperature (Tm) and calorimetric enthalpy (ΔH). Biological activity of lysozyme was determined by measuring decrease in A (450) when it was added to a suspension of Micrococcus lysodeikticus. The results of this study indicate that terpenes 9, 10, and 11 (carvone, L-fenchone, and L-verbenone) decreased conformational stability and biological activity of lysozyme significantly (p < 0.05) less than other terpenes used in this study. It is concluded that smaller terpenes containing ketones with low lipophilicity (log K (ow) ∼2.00) would be optimal for preserving conformational stability and biological activity of lysozyme in a transdermal formulation containing terpene as permeation enhancer.

  14. Investigating the effect of hydro-alcoholic extract of Salix aegyptiaca on anxiety in male rat

    PubMed Central

    Komaki, Alireza; Hashemi-Firouzi, Nasrin; Kakaei, Sahar; Shahidi, Siamak; Sarihi, Abdolrahman; Salehi, Iraj

    2015-01-01

    Background: Anxiety disorders are frequently common neuropsychiatric disorders. Herbal medicines are widespread and used universal as a treatment compound for anxiety. The present study investigated the effects of hydro-alcoholic extract of Salix aegyptiaca blossom on rat behavior in the elevated plus-maze (EPM) and compared results with the effects of diazepam, as a positive control drug. Materials and Methods: Seventy adult male Wistar rats were divided into seven groups (N = 10). Animals received S. aegyptiaca extract (25, 50, 100 mg/kg) or Diazepam (0.3, 0.6, or 1.2 mg/kg) intraperitoneally and the control group was given the vehicle (10 ml/kg) 30 min before submitting into plus-maze test. The number of entries into the open and closed arms, the percentage of entries into the open arms of the EPM, and the time spent in the open arms were recorded. Results: The results revealed significant increases in percentage of entries into the open arms (P < 0.01) and in the time spent in the open arms (P < 0.01) after administration of diazepam (0.3, 0.6) and S. aegyptiaca (50, 100 mg/kg) in compare with control group. S. aegyptiaca extract has no effects on the total distance covered by animals and number of closed arms entries, whereas diazepam decreased these parameters. The locomotor activity was not significantly changed by S. aegyptiaca. Conclusion: Single-session administration of optimum doses of total extract of S. aegyptiaca has anxiolytic effects in rat similar to the low dose of diazepam. More research is needed for better understanding of anxiolytic properties and neurobiological mechanisms of action and probable interactions of S. aegyptiaca extract with neurotransmitters. PMID:26918240

  15. Numerical Investigation of the Yarkovsky Effect: Mutiny on the High e's

    NASA Astrophysics Data System (ADS)

    Spitale, J. N.; Greenberg, R.

    1999-09-01

    The Yarkovsky effect, in which a body is accelerated by the reaction to thermal reradiation, may play a key role in the orbital evolution of asteroids and near-Earth objects. To evaluate the acceleration under various conditions, a three-dimensional finite-difference solution to the heat equation is applied to homogeneous, spherical bodies with 1-, 10- and 100m diameters. This approach employs neither the linearization, the plane-parallel approximation, nor the assumption of fast rotation used in earlier work (Rubincam, JGR 100:1685 1995, JGR 103:1725 1998; Vokrouhlicky, AJ 116:2032 1998), allowing exploration of a wide range of orbital elements and physical properties. Our work agrees with earlier results in the regimes where their approximations are valid. We investigate both the "seasonal" (obliquity = pi /2) and "diurnal" (obliquity = 0) extremes of the Yarkovsky effect, as well as the general case of intermediate obliquity. The numerical approach is applied to large eccentricities, where we find that the semimajor axis and eccentricity can change much faster than for circular orbits. For such orbits, the orientation of the rotation axis with respect to the direction of pericenter is critical in determining the evolution. For certain orientations, the seasonal Yarkovsky effect can cause both the semimajor axis and eccentricity to increase, contrary to previous expectations that the semimajor axis should always decrease (op. cit. Rubincam, Vokrouhlicky). An important implication of this work is that the Yarkovsky effect may remove an asteroid from resonance once its eccentricity has been sufficiently excited, but before the eccentricity grows so large that the asteroid is lost. This mechanism might significantly increase the efficiency for delivery of asteroids from the main belt to the terrestrial planets via the strong resonances. This work is funded by NASA PG&G grant NAG5-3631.

  16. Large-Eddy Simulations of Trade Wind Cumuli: Investigation of Aerosol Indirect Effects.

    NASA Astrophysics Data System (ADS)

    Xue, Huiwen; Feingold, Graham

    2006-06-01

    The effects of aerosol on warm trade cumulus clouds are investigated using a large-eddy simulation with size-resolved cloud microphysics. It is shown that, as expected, increases in aerosols cause a reduction in precipitation and an increase in the cloud-averaged liquid water path (LWP). However, for the case under study, cloud fraction, cloud size, cloud-top height, and depth decrease in response to increasing aerosol concentration, contrary to accepted hypotheses associated with the second aerosol indirect effect. It is found that the complex responses of clouds to aerosols are determined by competing effects of precipitation and droplet evaporation associated with entrainment. As aerosol concentration increases, precipitation suppression tends to maintain the clouds and lead to higher cloud LWP, whereas cloud droplets become smaller and evaporate more readily, which tends to dissipate the clouds and leads to lower cloud fraction, cloud size, and depth. An additional set of experiments with higher surface latent heat flux, and hence higher LWP and drizzle rate, was also performed. Changes in cloud properties due to aerosols have the same trends as in the base runs, although the magnitudes of the changes are larger. Evidence for significant stabilization (or destabilization) of the subcloud layer due to drizzle is not found, mainly because drizzling clouds cover only a small fraction of the domain. It is suggested that cloud fraction may only increase with increasing aerosol loading for larger clouds that are less susceptible to entrainment and evaporation. Finally, it is noted that at any given aerosol concentration the dynamical variability in bulk cloud parameters such as LWP tends to be larger than the aerosol-induced changes in these parameters, indicating that the second aerosol indirect effect may be hard to measure in this cloud type. The variability in cloud optical depth is, however, dominated by changes in aerosol, rather than dynamics.


  17. Effects of porosity on the fatigue performance of polymethyl methacrylate bone cement: an analytical investigation.

    PubMed

    Evans, S L

    2006-01-01

    Porosity has been shown to affect the fatigue life of bone cements, but, although vacuum mixing is widely used to reduce porosity in the clinical setting, results have been mixed and the effects of porosity are not well understood. The aim of this study was to investigate the effects of porosity using stress analysis and fracture mechanics techniques. The stress concentrations arising at voids in test specimens were found using analytical solutions and boundary element methods. The fatigue life of specimens containing voids of various sizes was predicted using fracture mechanics techniques. For spherical voids that do not occupy a significant proportion of the cross-section, the resulting stress concentration is independent of void size and too small to account for the observed crack initiation. Cracks must therefore initiate at additional stress raisers such as radiopacifier particles or additional voids. For large voids, the stress increases as the remaining cross-section of the specimen decreases, and this may account for much of the observed reduction in fatigue strength in hand-mixed cement. Although crack initiation may be largely independent of void size, there is an effect on crack growth rate. Cracks are predicted to grow faster around larger voids, since they remain in the stress concentration around the void for longer. This effect may account for the relationship between porosity and fatigue life that has been observed in samples without large voids. Since porosity appears to affect crack growth more than initiation, it may be less damaging in high-cycle clinical fatigue, which may be predominantly initiation controlled, than in short laboratory tests.

  18. Investigation into the effects of VHF and UHF band radiation on Hewlett-Packard (HP) Cesium Beam Frequency Standards

    NASA Technical Reports Server (NTRS)

    Dickens, Andrew

    1995-01-01

    This paper documents an investigation into reports which have indicated that exposure to VHF and UHF band radiation has adverse effects on the frequency stability of HP cesium beam frequency standards. Tests carried out on the basis of these reports show that sources of VHF and UHF radiation such as two-way hand held police communications devices do cause reproducible adverse effects. This investigation examines reproducible effects and explores possible causes.

  19. Investigation of HZETRN 2010 as a Tool for Single Event Effect Qualification of Avionics Systems

    NASA Technical Reports Server (NTRS)

    Rojdev, Kristina; Atwell, William; Boeder, Paul; Koontz, Steve

    2014-01-01

    NASA's future missions are focused on deep space for human exploration that do not provide a simple emergency return to Earth. In addition, the deep space environment contains a constant background Galactic Cosmic Ray (GCR) radiation exposure, as well as periodic Solar Particle Events (SPEs) that can produce intense amounts of radiation in a short amount of time. Given these conditions, it is important that the avionics systems for deep space human missions are not susceptible to Single Event Effects (SEE) that can occur from radiation interactions with electronic components. The typical process to minimizing SEE effects is through using heritage hardware and extensive testing programs that are very costly. Previous work by Koontz, et al. [1] utilized an analysis-based method for investigating electronic component susceptibility. In their paper, FLUKA, a Monte Carlo transport code, was used to calculate SEE and single event upset (SEU) rates. This code was then validated against in-flight data. In addition, CREME-96, a deterministic code, was also compared with FLUKA and in-flight data. However, FLUKA has a long run-time (on the order of days), and CREME-96 has not been updated in several years. This paper will investigate the use of HZETRN 2010, a deterministic transport code developed at NASA Langley Research Center, as another tool that can be used to analyze SEE and SEU rates. The benefits to using HZETRN over FLUKA and CREME-96 are that it has a very fast run time (on the order of minutes) and has been shown to be of similar accuracy as other deterministic and Monte Carlo codes when considering dose [2, 3, 4]. The 2010 version of HZETRN has updated its treatment of secondary neutrons and thus has improved its accuracy over previous versions. In this paper, the Linear Energy Transfer (LET) spectra are of interest rather than the total ionizing dose. Therefore, the LET spectra output from HZETRN 2010 will be compared with the FLUKA and in-flight data to validate

  20. An in vitro investigation of endocrine disrupting effects of the mycotoxin alternariol

    SciTech Connect

    Frizzell, Caroline; Ndossi, Doreen; Kalayou, Shewit; Eriksen, Gunnar S.; Verhaegen, Steven; Sørlie, Morten; Elliott, Christopher T.; Ropstad, Erik; Connolly, Lisa

    2013-08-15

    Alternariol (AOH) is a mycotoxin commonly produced by Alternaria alternata on a wide range of foods. Few studies to date have been performed to evaluate the effects of AOH on endocrine activity. The present study makes use of in vitro mammalian cellular based assays and gene expression to investigate the ability of AOH to act as an endocrine disruptor by various modes of action. Reporter gene assays (RGAs), incorporating natural steroid hormone receptors for oestrogens, androgens, progestagens and glucocorticoids were used to identify endocrine disruption at the level of nuclear receptor transcriptional activity, and the H295R steroidogenesis assay was used to assess endocrine disruption at the level of gene expression and steroid hormone production. AOH exhibited a weak oestrogenic response when tested in the oestrogen responsive RGA and binding of progesterone to the progestagen receptor was shown to be synergistically increased in the presence of AOH. H295R cells when exposed to 0.1–1000 ng/ml AOH, did not cause a significant change in testosterone and cortisol hormones but exposure to 1000 ng/ml (3.87 μM) AOH resulted in a significant increase in estradiol and progesterone production. In the gene expression study following exposure to 1000 ng/ml (3.87 μM) AOH, only one gene NR0B1 was down-regulated, whereas expression of mRNA for CYP1A1, MC2R, HSD3B2, CYP17, CYP21, CYP11B2 and CYP19 was up-regulated. Expression of the other genes investigated did not change significantly. In conclusion AOH is a weak oestrogenic mycotoxin that also has the ability to interfere with the steroidogenesis pathway. - Highlights: • Alternariol was investigated for endocrine disrupting activity. • Reporter gene assays and the H295R steroidogenesis assay have been used. • An oestrogenic effect of alternariol was observed. • This can lead to an increase in expression of the progesterone receptor. • Alternariol is capable of modulating hormone production and gene expression.