Science.gov

Sample records for 0-15 cm depth

  1. Magnetic field penetration depth of La(1.85)Sr(0.15)CuO4 measured by muon spin relaxation

    NASA Technical Reports Server (NTRS)

    Kossler, W. J.; Kempton, J. R.; Yu, X. H.; Schone, H. E.; Uemura, Y. J.

    1987-01-01

    Muon-spin-relaxation measurements have been performed on a high-Tc superconductor La(1.85)Sr(0.15)CuO4. In an external transverse magnetic field of 500 G, a magnetic field penetration depth of 2000 A at T = 10 K has been determined from the muon-spin-relaxation rate which increased with decreasing temperature below Tc. From this depth and the Pauli susceptibility, the superconducting carrier density is estimated at 3 x 10 to the 21st per cu cm. The zero-field relaxation rates above and below Tc were equal, which suggests that the superconducting state in this sample is not associated with detectable static magnetic ordering.

  2. Mid-continent fall temperatures at the 10-cm soil depth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recommendations for applying N-fertilizer in autumn involve delaying applications until daily soil temperature at 10 cm depth is = or < 10° C. Daily soil temperature data during autumn were examined from 26 sites along a transect from 36° to 49° N latitude in the mid-continent USA. After soils first...

  3. Muon and neutrino results from KGF experiment at a depth of 7000 hg/square cm

    NASA Technical Reports Server (NTRS)

    Krishnaswamy, M. R.; Menon, M. G. K.; Mondal, N. K.; Narasimham, V. S.; Streekantan, B. V.; Hayashi, Y.; Ito, N.; Kawakami, S.; Miyake, S.

    1985-01-01

    The KGF nucleon decay experiment at a depth of 7000 hg/sq cm has provided valuable data on muons and neutrinos. The detector comprised of 34 crossed layers of proportional counters (cross section 10 x 10 sq cm; lengths 4m and 6m) sandwiched between 1.2 cm thick iron plates can record tracks of charged particles to an accuracy of 1 deg from tracks that traverse the whole of the detector. A special two-fold coincidence system enables the detector to record charged particles that enter at very large zenith angles. In a live time of 3.6 years about 2600 events have been recorded. These events include atmospheric muons, neutrino induced muons from rock, stopping muons, showers and events which have their production vertex inside the detectors. The results on atmospheric muons and neutrino events are presented.

  4. A case study demonstration of the soil temperature extrema recovery rates after precipitation cooling at 10-cm soil depth

    NASA Technical Reports Server (NTRS)

    Welker, Jean Edward

    1991-01-01

    Since the invention of maximum and minimum thermometers in the 18th century, diurnal temperature extrema have been taken for air worldwide. At some stations, these extrema temperatures were collected at various soil depths also, and the behavior of these temperatures at a 10-cm depth at the Tifton Experimental Station in Georgia is presented. After a precipitation cooling event, the diurnal temperature maxima drop to a minimum value and then start a recovery to higher values (similar to thermal inertia). This recovery represents a measure of response to heating as a function of soil moisture and soil property. Eight different curves were fitted to a wide variety of data sets for different stations and years, and both power and exponential curves were fitted to a wide variety of data sets for different stations and years. Both power and exponential curve fits were consistently found to be statistically accurate least-square fit representations of the raw data recovery values. The predictive procedures used here were multivariate regression analyses, which are applicable to soils at a variety of depths besides the 10-cm depth presented.

  5. Precise Measurement of the Reionization Optical Depth from the Global 21 cm Signal Accounting for Cosmic Heating

    NASA Astrophysics Data System (ADS)

    Fialkov, Anastasia; Loeb, Abraham

    2016-04-01

    As a result of our limited data on reionization, the total optical depth for electron scattering, τ, limits precision measurements of cosmological parameters from the Cosmic Microwave Background (CMB). It was recently shown that the predicted 21 cm signal of neutral hydrogen contains enough information to reconstruct τ with sub-percent accuracy, assuming that the neutral gas was much hotter than the CMB throughout the entire epoch of reionization (EoR). Here we relax this assumption and use the global 21 cm signal alone to extract τ for realistic X-ray heating scenarios. We test our model-independent approach using mock data for a wide range of ionization and heating histories and show that an accurate measurement of the reionization optical depth at a sub-percent level is possible in most of the considered scenarios even when heating is not saturated during the EoR, assuming that the foregrounds are mitigated. However, we find that in cases where heating sources had hard X-ray spectra and their luminosity was close to or lower than what is predicted based on low-redshift observations, the global 21 cm signal alone is not a good tracer of the reionization history.

  6. Estimation of CO2 diffusion coefficient at 0-10 cm depth in undisturbed and tilled soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diffusion coefficients (D) of CO2 at 0 – 10 cm layers in undisturbed and tilled soil conditions were estimated using Penman, Millington-Quirk, Ridgwell et al. (1999), Troeh et al., and Moldrup et al. models. Soil bulk density and volumetric soil water content ('v) at 0 – 10 cm were measured on April...

  7. Depth

    PubMed Central

    Koenderink, Jan J; van Doorn, Andrea J; Wagemans, Johan

    2011-01-01

    Depth is the feeling of remoteness, or separateness, that accompanies awareness in human modalities like vision and audition. In specific cases depths can be graded on an ordinal scale, or even measured quantitatively on an interval scale. In the case of pictorial vision this is complicated by the fact that human observers often appear to apply mental transformations that involve depths in distinct visual directions. This implies that a comparison of empirically determined depths between observers involves pictorial space as an integral entity, whereas comparing pictorial depths as such is meaningless. We describe the formal structure of pictorial space purely in the phenomenological domain, without taking recourse to the theories of optics which properly apply to physical space—a distinct ontological domain. We introduce a number of general ways to design and implement methods of geodesy in pictorial space, and discuss some basic problems associated with such measurements. We deal mainly with conceptual issues. PMID:23145244

  8. Droplet size spectra and water-vapor concentration of laboratory water clouds: inversion of Fourier transform infrared (500-5000 cm(-1)) optical-depth measurement.

    PubMed

    Arnott, W P; Schmitt, C; Liu, Y; Hallett, J

    1997-07-20

    Infrared extinction optical depth (500-5000 cm(-1)) has been measured with a Fourier transform infrared spectrometer for clouds produced with an ultrasonic nebulizer. Direct measurement of the cloud droplet size spectra agree with size spectra retrieved from inversion of the extinction measurements. Both indicate that the range of droplet sizes is 1-14 mum. The retrieval was accomplished with an iterative algorithm that simultaneously obtains water-vapor concentration. The basis set of droplet extinction functions are computed once by using numerical integration of the Lorenz-Mie theory over narrow size bins, and a measured water-vapor extinction curve was used. Extinction and size spectra are measured and computed for both steady-state and dissipating clouds. It is demonstrated that anomalous diffraction theory produces relatively poor droplet size and synthetic extinction spectra and that extinction measurements are helpful in assessing the validity of various theories. Calculations of cloud liquid-water content from retrieved size distributions agree with a parameterization based on optical-depth measurements at a wave number of 906 cm(-1) for clouds that satisfy the size spectral range assumptions of the parameterization. Significance of droplet and vapor contribution to the total optical depth is used to evaluate the reliability of spectral inversions. PMID:18259335

  9. 47 CFR 0.15 - Functions of the Office.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.15 Section 0.15 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Media Relations § 0.15 Functions of the Office. (a) Enhance public understanding of and compliance with the Commission's regulatory...

  10. 28 CFR 0.15 - Deputy Attorney General.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., or political opinion. (2) Review cases decided by the Board of Immigration Appeals pursuant to 8 CFR... Register citations affecting § 0.15, see the List of CFR Sections Affected, which appears in the Finding... Executive Office of the President. (4) Coordinate and control the Department's reaction to...

  11. 28 CFR 0.15 - Deputy Attorney General.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., or political opinion. (2) Review cases decided by the Board of Immigration Appeals pursuant to 8 CFR... Register citations affecting § 0.15, see the List of CFR Sections Affected, which appears in the Finding... disturbances and terrorism. (5) Perform such other duties and functions as may be assigned from time to time...

  12. 28 CFR 0.15 - Deputy Attorney General.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., or political opinion. (2) Review cases decided by the Board of Immigration Appeals pursuant to 8 CFR... Register citations affecting § 0.15, see the List of CFR Sections Affected, which appears in the Finding... and programs and in providing overall supervision and direction to all organizational units of...

  13. UNIFORM INFALL TOWARD THE COMETARY H II REGION IN THE G34.26+0.15 COMPLEX?

    SciTech Connect

    Liu, Tie; Wu, Yuefang; Zhang, Huawei E-mail: ywu@pku.edu.cn

    2013-10-10

    Gas accretion is a key process in star formation. However, gas infall detections in high-mass, star-forming regions with high spatial resolution observations are rare. Here, we report the detection of gas infall toward a cometary ultracompact H II region ({sup C)} in the G34.26+0.15 complex. The observations were made with the IRAM 30 m, the James Clerk Maxwell Telescope 15 m telescope, and the Submillimeter Array (SMA). The hot core associated with 'C' has a mass of ∼76 ± 11 M{sub ☉} and a volume density of (1.1 ± 0.2) × 10{sup 8} cm{sup –3}. The HCN (3-2) and HCO{sup +} (1-0) lines observed by single dishes and the CN (2-1) lines observed by the SMA show redshifted absorption features, indicating gas infall. We found a linear relationship between the line width and optical depth of the CN (2-1) lines. Those transitions with larger optical depths and line widths have larger absorption areas. However, the infall velocities measured from different lines seem to be constant, indicating that the gas infall is uniform. We also investigated the evolution of gas infall in high-mass, star-forming regions. A tight relationship was found between the infall velocity and the total dust/gas mass. At stages prior to the hot core phase, the typical infall velocity and mass infall rate are ∼1 km s{sup –1} and ∼10{sup –4} M{sub ☉} yr{sup –1}, respectively. While in more evolved regions, the infall velocity and mass infall rates can reach as high as several km s{sup –1} and ∼10{sup –3}-10{sup –2} M{sub ☉} yr{sup –1}, respectively. Accelerated infall has been detected toward some hypercompact H II and ultracompact H II regions. However, the acceleration phenomenon is not seen in more evolved ultracompact H II regions (e.g., G34.26+0.15)

  14. Quantitative x-ray diffraction analysis of bimodal damage distributions in Tm implanted Al0.15Ga0.85N

    NASA Astrophysics Data System (ADS)

    Magalhães, S.; Fialho, M.; Peres, M.; Lorenz, K.; Alves, E.

    2016-04-01

    In this work radial symmetric x-ray diffraction scans of Al0.15Ga0.85N thin films implanted with Tm ions were measured to determine the lattice deformation and crystal quality as functions of depth. The alloys were implanted with 300 keV Tm with 10° off-set to the sample normal to avoid channelling, with fluences varying between 1013 Tm cm-2 and 5  ×  1015 Tm cm-2. Simulations of the radial 2θ-ω scans were performed under the frame of the dynamical theory of x-ray diffraction assuming Gaussian distributions of the lattice strain induced by implantation defects. The structure factor of the individual layers is multiplied by a static Debye-Waller factor in order to take into account the effect of lattice disorder due to implantation. For higher fluences two asymmetric Gaussians are required to describe well the experimental diffractograms, although a single asymmetric Gaussian profile for the deformation is found in the sample implanted with 1013 Tm cm-2. After thermal treatment at 1200 °C, the crystal quality partially recovers as seen in a reduction of the amplitude of the deformation maximum as well as the total thickness of the deformed layer. Furthermore, no evidence of changes with respect to the virgin crystal mosaicity is found after implantation and annealing.

  15. Synthesis and Hydrogen Desorption Properties of Mg1.7Al0.15Ti0.15Ni-CNT Nanocomposite Powder

    NASA Astrophysics Data System (ADS)

    Enayati, M. H.; Karimzadeh, F.; Jafari, M.; Sabooni, S.

    2015-03-01

    In this research, the effects of nanocrystallization and incorporation of aluminum, titanium, and carbon nanotubes (CNTs) on hydrogen desorption behavior of Mg2Ni alloy were investigated. Toward this purpose, nanocrystalline Mg2Ni intermetallic compound with average grain size of 20 nm was prepared by ball milling of elemental magnesium and nickel powders. Mg2Ni powder was then ball milled with aluminum and titanium powders for 20 h to dissolve these elements into the Mg2Ni structure, leading to the formation of Mg1.7Al0.15Ti0.15Ni compound. The elemental x-ray mapping analysis revealed the uniform dissolution of aluminum and titanium inside the Mg2Ni structure. Mg2Ni and Mg1.7Al0.15Ti0.15Ni compounds were further ball milled with 3 wt.% CNT for 5 h. The high-resolution field emission scanning electron microscopy and transmission electron microscopy revealed that CNTs have retained their tubular shape after ball-milling process. The hydrogen desorption properties of the samples were identified using a Sieverts-type apparatus at 473 K. The Mg2Ni, Mg2Ni-CNT, and Mg1.7Ti0.15Al0.15-CNT samples showed the desorbed hydrogen of 0.17, 0.25, and 0.28 wt.% after 1 h, respectively, indicating 47 and 65% increase in the hydrogen desorption capability of Mg2Ni via CNT addition and co-presence of aluminum-titanium-CNT. The direct hydrogen diffusion through CNTs and development of local atomic distortion due to substitution of magnesium atoms by aluminum and titanium appears to be responsible for enhancement of desorption behavior of Mg1.7Al0.15Ti0.15-3 wt.% CNT.

  16. Unconventional superconductivity in CaFe0.85Co0.15AsF evidenced by torque measurements

    NASA Astrophysics Data System (ADS)

    Xiao, Hong; Li, X. J.; Mu, G.; Hu, T.

    Out-of-plane angular dependent torque measurements were performed on CaFe0.85Co0.15AsF single crystals. Abnormal superconducting fluctuation, featured by enhanced diamagnetism with magnetic field, is detected up to about 1.5 times superconducting transition temperature Tc. Compared to cuprate superconductors, the fluctuation effect in iron-based superconductor is less pronounced. Anisotropy parameter γ is obtained from the mixed state torque data and it is found that γ shows both magnetic field and temperature depenence, pointing to multiband superconductivity. The temperature dependence of penetration depth λ (T) suggests unconventional superconductivity in CaFe0.85Co0.15AsF.

  17. Disorder - driven phase transition in La0.37Bi0.15Sm0.15Ca0.33MnO3

    NASA Astrophysics Data System (ADS)

    Ade, Ramesh; Singh, R.

    2015-06-01

    We report the effect of disorder on the properties of La0.37Bi0.15Sm0.15Ca0.33MnO3 manganite synthesized by sol - gel method. The critical properties were investigated through various techniques such as modified - Arrott plot, Kouvel - Fisher method and critical isotherm analysis. The sample show second- order phase transition near critical point. The decrease in magnetization (M), Curie temperature (TC), evolution of spin or cluster glass behavior and the nature of phase transition compared to first - order transition in La0.67Ca0.33MnO3 are ascribed to the disorder caused by the size mismatch of the A-site cations with Bi and Sm doping at La- site.

  18. Ferroelectric properties of pulsed laser deposited Ba(Zr0.15Ti0.85)O3 thin films

    NASA Astrophysics Data System (ADS)

    James, A. R.; Prakash, Chandra

    2004-02-01

    Thin films of Ba(Zr0.15Ti0.85)O3 were crystallized in situ at several different oxygen background pressures and temperatures. The optimal temperature and pressure for obtaining films with smooth surface morphology and good electrical properties was found to be 675 °C and 300 mTorr, respectively. Films grown at this temperature were found to have a Pr of 3.31 μC/cm2 and an Ec of 93.5 kV/cm. Low field dielectric measurements and C-V measurements were performed in order to study the dielectric behavior of the films. A tunability of ˜45% was recorded on the films.

  19. Growth and dislocation etching of InBi 1-xSe x ( x=0.15) single crystals

    NASA Astrophysics Data System (ADS)

    Shah, Dimple; Pandya, G. R.; Vyas, S. M.

    2009-01-01

    Single crystals of InBi 0.85 Se .15 ( x=0.15) have been grown by the zone melting method. The freezing interface temperature gradient was 65 °C/cm and the best-quality single crystal has been obtained at growth velocity 1.5 cm/h. The crystals grown by the zone melting method have been observed to exhibit certain typical features on their top free surfaces. The energy dispersive analysis of X-ray (EDAX) technique has been used for testing the presence of constituent element of InBi:Se single crystal. A new dislocation etchant has been developed by the successive trial-error method. The dislocation etchant has been found to give reproducible etch-pits on the cleavage surface. Various standard tests for a dislocation etchant have been carried out and results are reported.

  20. Ganciclovir ophthalmic gel, 0.15%: a valuable tool for treating ocular herpes

    PubMed Central

    Colin, Joseph

    2007-01-01

    Ocular herpes simplex virus (HSV) infection remains a major cause of corneal blindness. Several topical and oral antiviral medications have been used to treat herpetic keratitis. Advances in topical ophthalmic antivirals have been made over the past several decades. The first antivirals that were discovered were cytotoxic, while the antivirals developed more recently, such as acyclovir and ganciclovir, have exceeded these drugs in both efficacy and tolerability. Commercially available outside of the US since 1996, ganciclovir ophthalmic gel, 0.15% (GCV 0.15%, European tradename: Virgan®) is sold in more than 30 countries and has become the standard of care in treating acute herpetic keratitis. GCV 0.15% has been studied in animal models of ocular herpes, in healthy volunteers, and in several clinical studies. It has been found to be safe and effective at treating acute superficial herpetic keratitis. Previous preclinical studies of ganciclovir have shown activity against several common adenovirus strains and one recent clinical study demonstrated clinical effect against adenoviral conjunctivitis. This review is intended to provide a comprehensive overview of the GCV 0.15%, including a brief summary of the etiology and available treatments for ocular HSV, an explanation of GCV 0.15% mechanism of action, a compendium of preclinical and clinical GCV 0.15% studies, and an introduction into new areas of interest involving this drug. PMID:19668521

  1. Variations in the depth distribution of phosphorus in soil profiles and implications for model-based catchment-scale predictions of phosphorus delivery to surface waters

    NASA Astrophysics Data System (ADS)

    Owens, P. N.; Deeks, L. K.; Wood, G. A.; Betson, M. J.; Lord, E. I.; Davison, P. S.

    2008-02-01

    SummaryThe PSYCHIC process-based model for predicting sediment and phosphorus (P) transfer within catchments uses spatial data on soil-P derived from the National Soil Inventory (NSI) data set. These soil-P values are based on bulked 0-15 cm depth and do not account for variations in soil-P with depth. We describe the depth distribution of soil-P (total and Olsen) in grassland and arable soils for the dominant soil types in the two PSYCHIC study catchments: the Avon and the Wye, UK. There were clear variations in soil-P (particularly Olsen-P) concentrations with depth in untilled grassland soils while concentrations of total-P were broadly constant within the plough layer of arable soils. Concentrations of Olsen-P in arable soils, however, exhibited maximum values near the soil surface reflecting surface applications of fertilisers and manures between consecutive ploughing events. When the soil-P concentrations for the surface soil (0-5 cm average) were compared to both the profile-averaged (0-15 cm) and the NSI (0-15 cm) values, those for the surface soil were considerably greater than those for the average 0-15 cm depth. Modelled estimates of P loss using the depth-weighted average soil-P concentrations for the 0-5 cm depth layer were up to 14% greater than those based on the NSI data set due to the preferential accumulation of P at the soil surface. These findings have important implications for the use of soil-P data (and other data) in models to predict P losses from land to water and the interpretation of these predictions for river basin management.

  2. Morphological and crystallographic evolution of bainite transformation in Fe-0.15C binary alloy.

    PubMed

    Zhang, Di; Terasaki, Hidenori; Komizo, Yuichi

    2010-01-01

    In this article, an in situ observation method, combining laser scanning confocal microscopy and electron backscattering diffraction, was used to investigate the morphological and crystallographic evolution of bainite transformation in a Fe-0.15C binary alloy. The nucleation at a grain boundary and inclusions, sympathetic nucleation, and impingement event of bainitic ferrite were directly shown in real time. The variant evolution during bainite transformation and misorientation between bainitic ferrites were clarified. Strong variant selection was observed during sympathetic nucleation. PMID:19588518

  3. Thermal and magnetic properties of copper potassium tutton salt below 0. 15 K

    SciTech Connect

    Fujii, Y.; Shigi, T.

    1988-08-01

    The specific heat and the ac susceptibility of copper potassium tutton salt have been measured between 0.01 and 0.15 K. The magnetic phase transition from the paramagnetic to the canted ferromagnetic state was observed at 29.5 mK in zero field. From the obtained electronic entropy curve this salt is considered to be a Heisenberg-type ferromagnet. The copper nuclear specific heat of the hyperfine splitting is estimated to be C/sub N/ = 1.1 /times/ 10/sup /minus/5/R/(T/sup 2//(K/sup 2/)), which is one order smaller than the value calculated from previous results of the paramagnetic resonance.

  4. Optical constraints of kerogen from 0.15 to 40 microns: Comparison with meteoritic organics

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N.; Thompson, W. R.; Sagan, C.; Arakawa, E. T.; Meisse, C.; Gilmour, I.

    1990-01-01

    Kerogens are dark, complex organic materials produced on the Earth primarily by geologic processing of biologic materials, but kerogens have chemical and spectral similarities to some classes of highly processed extraterrestrial organic materials. Kerogen-like solids were proposed as constitutents of the very dark reddish surfaces of some asteroids and are also spectrally similar to some carbonaceous organic residues and the Iapetus dark material. Kerogen can thus serve as a useful laboratory analog to very dark, spectrally red extraterrestrial materials; its optical constants can be used to investigate the effects of particle size, void space and mixing of bright and dark components in models of scattering by dark asteroidal, cometary, and satellite surfaces. Measurements of the optical constants of both Type 2 kerogen and of macromolecular organic residue from the Murchison carbonaceous chondrite via transmission and reflection measurements on thin films are reported. The real part of the refractive index, n, is determined by variable incidence-angle reflectance to be 1.60 + or - 0.05 from 0.4 to 2.0 micrometers wavelength. Work extending the measurement of n to longer wavelengths is in progress. The imaginary part of the refractive index, k, shows substantial structure from 0.15 to 40 micrometers. The values are accurate to + or - 20 percent in the UV and IR regions and to + or - 30 percent in the visible. The k values of organic residues were also measured from the Murchison meteorite. Comparison of the kerogen and Murchison data reveals that between 0.15 and 40 microns, Murchison has a similar structure but no bands as sharp as in kerogen, and that the k values for Murchison are significantly higher than those of kerogen.

  5. Ubiquitous CM and DM

    NASA Technical Reports Server (NTRS)

    Crowley, Sandra L.

    2000-01-01

    Ubiquitous is a real word. I thank a former Total Quality Coach for my first exposure some years ago to its existence. My version of Webster's dictionary defines ubiquitous as "present, or seeming to be present, everywhere at the same time; omnipresent." While I believe that God is omnipresent, I have come to discover that CM and DM are present everywhere. Oh, yes; I define CM as Configuration Management and DM as either Data or Document Management. Ten years ago, I had my first introduction to the CM world. I had an opportunity to do CM for the Space Station effort at the NASA Lewis Research Center. I learned that CM was a discipline that had four areas of focus: identification, control, status accounting, and verification. I was certified as a CMIl graduate and was indoctrinated about clear, concise, and valid. Off I went into a world of entirely new experiences. I was exposed to change requests and change boards first hand. I also learned about implementation of changes, and then of technical and CM requirements.

  6. 21-cm Intensity Mapping

    NASA Astrophysics Data System (ADS)

    Chang, Tzu-Ching; GBT-HIM Team

    2016-01-01

    The redshifted 21-cm emission from neutral hydrogen has emerged as a powerful probe for large-scale structure; a significant fraction of the observable universe can be mapped in the Intensity Mapping regime out to high redshifts. At redshifts around unity, the 21-cm emission traces the matter distribution and can be used to measure the Baryon Acoustic Oscillation (BAO) signature and constrain dark energy properties. I will describe our HI Intensity Mapping program at the Green Bank Telescope (GBT), aiming at measuring the 21cm power spectrum at z=0.8. A 800-MHz multi-beam focal-plane array for the GBT is currently under construction in order to facilitate a large-scale survey for BAO and the redshift-space distortion measurements for cosmological constraints.

  7. Evaluation of the SC-1/megasonic clean for sub-0.15 micron particle removal

    SciTech Connect

    Adkins, C.L.J.; Resnick, P.J.; Clews, P.J.; Thomas, E.V.; Korbe, N.C.; Cannaday, S.T.

    1994-07-01

    A statistical design of experiments approach has been employed to evaluate the particle removal efficacy of the SC-1/megasonic clean for sub-0.15 {mu}m inorganic particles. The effects of megasonic input power, solution chemistry, bath temperature, and immersion time have been investigated. Immersion time was not observed to be a statistically significant factor. The NH{sub 4}OH/H{sub 2}O{sub 2} ratio was significant, but varying the molar H{sub 2}O{sub 2} concentration had no effect on inorganic particle removal. Substantially diluted chemistries, performed with high megasonic input power and moderate-to-elevated temperatures, was shown to be very effective for small particle removal. Bath composition data show extended lifetimes can be obtained when high purity chemicals are used at moderate (eg., 45{degrees}C) temperature. Transition metal surface concentrations and surface roughness have been measured after dilute SC-1 processing and compared to metallic contamination following traditional SC-1.

  8. The mass function of ω Centauri down to 0.15 Msolar

    NASA Astrophysics Data System (ADS)

    Sollima, A.; Ferraro, F. R.; Bellazzini, M.

    2007-11-01

    By means of deep FORS1/VLT and ACS/Hubble Space Telescope observations of a wide area in the stellar system ω Cen we measured the luminosity function of main-sequence stars down to R = 22.6 and IF814W = 24.5. The luminosity functions obtained have been converted into mass functions and compared with analytical initial mass functions (IMFs) available in the literature. The mass function obtained, reaching M ~ 0.15Msolar, can be well reproduced by a broken power law with indices α = -2.3 for M > 0.5Msolar and α = -0.8 for M < 0.5Msolar. Since the stellar populations of ω Cen have been proved to be actually unaffected by dynamical evolution processes, the mass function measured in this stellar system should represent the best approximation of the IMF of a star cluster. The comparison with the MF measured in other Galactic globular clusters suggests that possible primordial differences in the slope of the low-mass end of their MF could exist. Based on observations collected at the European Southern Observatory within the observing program 74.D-0369(B). Also based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. E-mail: antonio.sollima@bo.astro.it

  9. Pulsed Laser Deposition of BaCe(sub 0.85)Y(sub 0.15)0(sub 3) FILMS

    NASA Technical Reports Server (NTRS)

    Dynys, F. W.; Sayir, A.

    2006-01-01

    Pulsed laser deposition has been used to grow nanostructured BaCe(sub 0.85)Y(sub 0.15)0(sub 3) films. The objective is to enhance protonic conduction by reduction of membrane thickness. Sintered samples and laser targets were prepared by sintering BaCe(sub 0.85)Y(sub 0.15)O(sub 3) powders derived by solid state synthesis. Films 2 to 6 m thick were deposited by KrF excimer laser on Si and porous Al2O3 substrates. Nanocrystalline films were fabricated at deposition temperatures of 600-800 C deg at O2 pressure of 30 mTorr and laser fluence of 1.2 J/cm square. Films were characterized by x-ray diffraction, scanning electron microscopy and electrical impedance spectroscopy. Dense single phase BaCe(sub 0.85)Y((sub 0.15) 0(sub 3) films with a columnar growth morphology is observed, preferred crystal growth was found to be dependent upon deposition temperature and substrate type. Electrical conductivity of bulk samples produced by solid state sintering and thin film samples were measured over a temperature range of 100 C deg to 900 C deg in moist argon. Electrical conduction of the fabricated films was 1 to 4 orders of magnitude lower than the sintered bulk samples. With respect to the film growth direction, activation energy for electrical conduction is 3 times higher in the perpendicular direction than the parallel direction.

  10. Halogens in CM Chondrites

    NASA Astrophysics Data System (ADS)

    Menard, J. M.; Caron, B.; Jambon, A.; Michel, A.; Villemant, B.

    2013-09-01

    We set up an extraction line of halogens (fluorine, chlorine) by pyrohydrolysis with 50 mg of rock. We analyzed 7 CM2 chondrites found in Antarctica and found that the Cl content of meteorites with an intact fusion crust is higher than those without.

  11. Inspection of an end quenched 0.15%-0.2% C, 0.6%-0.9% Mn steel jominy bar with photothermal radiometric techniques

    NASA Astrophysics Data System (ADS)

    Liu, Yue; Baddour, Natalie; Mandelis, Andreas; Wang, Chinhua

    2004-08-01

    The effect of the cooling rate on hardness and thermal conductivity in a metallurgical Jominy bar made of 0.15%-0.2% C, 0.6%-0.9% Mn (AISI 1018) steel, by means of a water end-quenched heat treatment process without diffusion-controlled case depth, is studied with photothermal radiometry (PTR). It is concluded that our two PTR techniques, common-mode rejection demodulation and conventional 50% duty-cycle square-wave frequency scan, are sensitive to low hardness values and gradients, unlike the high values all previous photothermal studies have dealt with to-date. Both PTR methods have yielded an anticorrelation between thermal conductivity and microhardness in this case as in previous cases with heat-treated and diffusion-controlled case depth profiles. It is shown that the cooling rate strongly affects both hardness and thermal conductivity in the Jominy-bar heat-treating process.

  12. Metallic Nonsuperconducting Phase and D -Wave Superconductivity in Zn-Substituted La{sub 1.85}Sr{sub 0.15}CuO{sub 4}

    SciTech Connect

    Karpinska, K.; Cieplak, Marta Z.; Guha, S.; Malinowski, A.; Skoskiewicz, T.; Plesiewicz, W.; Berkowski, M.; Boyce, B.; Lemberger, Thomas R.; Lindenfeld, P.

    2000-01-03

    Measurements of the resistivity, magnetoresistance, and penetration depth were made on films of La{sub 1.85} Sr{sub 0.15} CuO{sub 4} , with up to 12 at. % of Zn substituted for the Cu. The results show that the quadratic temperature dependence of the inverse square of the penetration depth, indicative of d -wave superconductivity, is not affected by doping. The suppression of superconductivity leads to a metallic nonsuperconducting phase, as expected for a pairing mechanism related to spin fluctuations. The metal-insulator transition occurs in the vicinity of k{sub F}l{approx_equal}1 , and appears to be disorder driven, with the carrier concentration unaffected by doping. (c) 1999 The American Physical Society.

  13. Perovskite Sr₁-xCexCoO₃-δ (0.05 ≤ x ≤ 0.15) as superior cathodes for intermediate temperature solid oxide fuel cells.

    PubMed

    Yang, Wei; Hong, Tao; Li, Shuai; Ma, Zhaohui; Sun, Chunwen; Xia, Changrong; Chen, Liquan

    2013-02-01

    Perovskite Sr(1-x)Ce(x)CoO(3-δ) (0.05 ≤ x ≤ 0.15) have been prepared by a sol-gel method and studied as cathodes for intermediate temperature solid oxide fuel cells. As SOFC cathodes, Sr(1-x)Ce(x)CoO(3-δ) materials have sufficiently high electronic conductivities and excellent chemical compatibility with SDC electrolyte. The peak power density of cells with Sr(0.95)Ce(0.05)CoO(3-δ) is 0.625 W cm(-2) at 700 °C. By forming a composite cathode with an oxygen ion conductor SDC, the peak power density of the cell with Sr(0.95)Ce(0.05)CoO(3-δ)-30 wt %SDC composite cathode, reaches 1.01 W cm(-2) at 700 °C, better than that of Sm(0.5)Sr(0.5)CoO(3)-based cathode. All these results demonstrates that Sr(1-x)Ce(x)CoO(3-δ) (0.05 ≤ x ≤ 0.15)-based materials are promising cathodes for an IT-SOFC. PMID:23336216

  14. Transparent magnetic state in single crystal Nd(1.85)Ce(0.15)CuO(4-y) superconductors

    NASA Technical Reports Server (NTRS)

    Zuo, F.

    1995-01-01

    Several experimental studies have been reported as evidence of Josephson coupling between the superconducting layers in the highly anisotropic oxide such as the Bi2Sr2CaCu2O8 and Tl2Ba2CuO6 systems. These include the large penetration depth of 100 mu m measured, ac and dc Josephson effects. Recently two critical temperatures corresponding to Josephson coupling in between the layers and the Berezinskii-Kosterlitz-Thouless transition in the ab-plane have been directly observed in the transport measurements. If the field is applied parallel to the superconducting layers, the magnetic excitation is not the conventional Abrikosov vortices, but the Josephson vortices which extend lambda(sub ab) in the c-axis direction and lambda(sub J) = gamma s in the plane (s is the interlayer distance, gamma is the anisotropy constant). Because of the weak screening effect associated with the Josephson vortices, there have been predictions of magnetic transparent states at magnetic field above a characteristic field H(sub J), a behavior distinctively different from that of the type-II superconductors. In this paper, we report an experimental result which illustrates a transition from the Meissner state to the magnetic transparent state in single crystal of Nd(1.85)Ce(0.15)CuO(4-y). Magnetization has been measured as a function of temperature and field in the magnetic field parallel or close to ab-plane geometry. For a fixed magnetic field, the magnetization shows a two-step transition in M(T); for a fixed temperature, the magnetization shows an abrupt change to almost zero value above a characteristic field H(sub J), an indication of magnetic transparent state. The data of magnetization as a function of field clearly deviates from the behavior predicted by the Abrikosov theory for type-II superconductors. Instead, the data fit well into the picture of Josephson decoupling between the CuO2 layers.

  15. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties

    PubMed Central

    2009-01-01

    We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer–Emment–Teller specific area (33.8 m2 g−1), strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent. PMID:20596394

  16. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties.

    PubMed

    Hou, Jing; Zuo, Guanke; Shen, Guangxia; Guo, He; Liu, Hui; Cheng, Ping; Zhang, Jingyan; Guo, Shouwu

    2009-01-01

    We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer-Emment-Teller specific area (33.8 m2 g-1), strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent. PMID:20596394

  17. Apparent Depth.

    ERIC Educational Resources Information Center

    Nassar, Antonio B.

    1994-01-01

    Discusses a well-known optical refraction problem where the depth of an object in a liquid is determined. Proposes that many texts incorrectly solve the problem. Provides theory, equations, and diagrams. (MVL)

  18. Magnetotransport and thermal properties characterization of 55 K superconductor SmFeAsO0.85F0.15

    NASA Astrophysics Data System (ADS)

    Srivastava, Amit; Pal, Anand; Singh, Saurabh; Shekhar, C.; Singh, H. K.; Awana, V. P. S.; Srivastava, O. N.

    2013-09-01

    This report fairly underlines the magneto-transport, thermal properties characterization and bulk superconductivity in the FeAs-based SmFeAsO0.85F0.1. The phase formation and structure are confirmed by Rietveld analysis of room temperature powder X-ray diffraction (XRD) data. Electron microscopy was employed to unravel the micro structural details, such as perfection of the lattice and the grain morphology including size and boundaries. The electrical and magnetic measurements have been carried out to confirm the bulk superconductivity and understand the nature of electrical transport in the normal and superconducting state. The intra-grain critical current density (Jc) with applied magnetic field is calculated from isothermal DC magnetization (MH) plots using conventional Bean critical state model. Superconductivity is observed at transition temperature (Tc) above 55 K without HPHT (high pressure high temperature) synthesis route. The value of Jc is found to be around 5.26 × 104 A/cm2 at 5 K in zero field. The dependence of thermally activated flux flow energy (U/kB) on the applied magnetic field has been observed. AC susceptibility measurements were performed for 55 K superconducting SmFeAsO0.85F0.15 sample at various amplitude of applied AC drive field and its granular nature is confirmed. The parent compound SmFeAsO is found to be magnetic with Fe spin density wave (SDW) like order below 150 K, on the other hand the F doped SmFeAsO0.85F0.15 sample is bulk superconducting at below 55 K. Both Fe (SDW) at 150 K for SmFeAsO and 55 K superconductivity in case of SmFeAsO0.85F0.15 sample has confirmed by Specific heat [Cp(T)] measurement too. Further Sm orders anti-ferro-magnetically at 4.5 K for non-superconducting and at 3.5 K for superconducting samples, also the entropy change is reduced significantly for the later than the former. Summarily complete physical property characterization for both non-superconducting SmFeAsO and 55 K superconductor SmFeAsO0.85F0.15

  19. Enhanced electric field tunable dielectric properties of Ba(Sn0.15Ti0.85)O3 thin films

    NASA Astrophysics Data System (ADS)

    Song, S. N.; Zhai, J. W.; Gao, L. N.; Yao, X.; Hung, T. F.; Xu, Z. K.

    2008-11-01

    Highly (100)-oriented barium stannate titanate Ba(Sn0.15Ti0.85)O3 (BTS) thin films were deposited on SrTiO3 (STO) and Nb doped SrTiO3 (NSTO) single-crystal substrates through sol-gel process, respectively. Coplanar capacitance and parallel plate capacitance structure configurations were formed by preparing interdigital electrodes (IDEs) and parallel plate electrodes (PPEs) on BTS thin film. The tunability of films with IDE was 45.54%, while the tunability of films with PPE was only 11.54% at the frequency of 1 MHz with an applied electric field of 80 kV/cm. This result showed that the tunability in the a-b plane contributes markedly to the measurements obtained with the IDE.

  20. Large pyroelectric figure of merits for Sr-modified Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics

    NASA Astrophysics Data System (ADS)

    Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

    2016-02-01

    In the present work ferroelectric, dielectric and pyroelectric properties of Sr-modified Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics were investigated. A significant increase in polarization has been observed, from 16 μC/cm2 to 25 μC/cm2 for 15% Sr added BCZT compositions. Correspondingly an improvement in dielectric constant, from 2743 to 4040, was observed at room temperature (1 MHz). It was found that Curie-Weiss temperature (TCW) decreases from 357 K to 308 K for 15% Sr containing BCZT ceramics. Simultaneously, it also enhances the order-disorder to displacing phase transition as γ varies from 1.91 to 1.31. Pyroelectric coefficient was found to be 25 μC/cm2K at 308 K. Finally, pyroelectric figures of merit (FOMs) for voltage responsivity (Fv), current responsivity (Fi), detectivity (Fd), energy harvesting (Fe) and new energy harvesting (Fe∗) are calculated. A large improvement in pyroelectric FOMs indicates that it might be a potential material for pyroelectric applications.

  1. Mn-doped 0.15BiInO3-0.85PbTiO3 piezoelectric films deposited by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Lee, Sun Young; Ko, Song Won; Lee, Soonil; Trolier-McKinstry, Susan

    2012-05-01

    Undoped, 0.5 and 1.0 mol. % Mn-doped 0.15BiInO3-0.85PbTiO3 films were grown on PbTiO3/Pt/Ti/SiO2/Si substrates by pulsed laser deposition. Phase-pure perovskite films were obtained at a substrate temperature of 585 °C irrespective of Mn doping level. The 0.5 mol. % Mn-doped films showed a room temperature permittivity of 480 and a dielectric loss tangent of 0.015 at 100 kHz after 650 °C post-deposition annealing. The coercive field and remanent polarization were 80 kV/cm and 29 µC/cm2, respectively. The ferroelectric transition temperature of the films ranged from 535 to 585 °C. The e31,f piezoelectric coefficient was -7.1 C/m2. X-ray diffraction and phase transition temperature data showed that the Mn atoms substitute on the Ti-site as Mn3+; the resulting films have p-type conduction characteristics.

  2. Synthesis and electrochemical performance of LiNi{sub 0.7}Co{sub 0.15}Mn{sub 0.15}O{sub 2} as gradient cathode material for lithium batteries

    SciTech Connect

    Zhang, Lipeng; Dong, Tao; Yu, Xianjin; Dong, Yunhui; Zhao, Zengdian; Li, Heng

    2012-11-15

    Highlights: ► The gradient precursors Ni{sub 0.7}Co{sub 0.15}Mn{sub 0.15}(OH){sub 2} is prepared by hydroxide co-precipitating. ► The cathode materials is synthesized by mixing the precursor with 5% excess LiOH·H{sub 2}O. ► The XRD results show that cathode materials present layered α-NaFeO{sub 2} typical crystal. ► Material sintered at 850 °C shows the best performance, with high-capacity and recyclability. -- Abstract: LiNi{sub 0.7}Co{sub 0.15}Mn{sub 0.15}O{sub 2} as a cathode material for lithium batteries was synthesized by mixing hydroxide co-precipitated precursors with 5% excess LiOH·H{sub 2}O. Its structural and electrochemical properties were investigated using X-ray diffractometry, scanning electron microscopy, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy. The results indicated that well-ordering layered LiNi{sub 0.7}Co{sub 0.15}Mn{sub 0.15}O{sub 2} cathode materials were successfully prepared in air at 750, 800, and 850°C with α-NaFeO{sub 2} typical crystal. The results of charge–discharge test demonstrated that the gradient cathode material sintered at 850 °C exhibited the best electrochemical performance with the initial discharge capacity of 164 mA h g{sup −1} at 0.2 C and lower electrochemical impedance. Nickel has low price. LiNiO{sub 2} cathode materials have high specific capacity, their theoretical capacity is 274 mA h g{sup −1} and with low self-discharge rate. So the Ni, Co, Mn ternary layer-structural compounds with high Ni content are showing to be promising cathode materials for lithium batteries. The techniques and research results in this paper are utilizable for the study of this kind of lithium battery materials.

  3. Disorder - driven phase transition in La{sub 0.37}Bi{sub 0.15}Sm{sub 0.15}Ca{sub 0.33}MnO{sub 3}

    SciTech Connect

    Ade, Ramesh; Singh, R.

    2015-06-24

    We report the effect of disorder on the properties of La{sub 0.37}Bi{sub 0.15}Sm{sub 0.15}Ca{sub 0.33}MnO{sub 3} manganite synthesized by sol – gel method. The critical properties were investigated through various techniques such as modified - Arrott plot, Kouvel - Fisher method and critical isotherm analysis. The sample show second- order phase transition near critical point. The decrease in magnetization (M), Curie temperature (T{sub C}), evolution of spin or cluster glass behavior and the nature of phase transition compared to first - order transition in La{sub 0.67}Ca{sub 0.33}MnO{sub 3} are ascribed to the disorder caused by the size mismatch of the A-site cations with Bi and Sm doping at La- site.

  4. Thermal and electric properties of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y)

    NASA Technical Reports Server (NTRS)

    Lim, Z. S.; Han, K. H.; Lee, Sung-Ik; Jeong, Yoon H.; Song, Y. S.; Park, Y. W.

    1991-01-01

    Electric resistivity, magnetic susceptibility, thermoelectric power, and Hall coefficient of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y) whose onset temperature of the superconductivity are 24 and 23 K were measured. Experimental results show many interesting features. In particular, the Hall coefficients are negative and relatively flat as a function of temperature. However, the temperature dependence of the thermoelectric power (TEP) for these two samples shows the positive sign for both samples in contrast to the previous results. Moreover, TEP for both samples remains flat in the normal state below 250 K, but decreases rapidly above 250 K. TEP of only Pr(1.85)Ce(0.15)CuO(4-y) shows a peak near 50 K. Finally, onset temperatures of sudden drop of TEP are higher than those of resistance drop. The physical properties of these samples produced at different conditions such as different heat treatment temperatures, atmospheres were also measured. TEP and resistance measurement show that oxygen deficiency is essential to produce better superconducting samples. Correlation between TEP and superconductivity for these different samples are discussed.

  5. Thermal and electric properties of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y)

    NASA Technical Reports Server (NTRS)

    Lim, Z. S.; Han, K. H.; Lee, Sung-Ik; Jeong, Yoon H.; Song, Y. S.; Park, Y. W.

    1990-01-01

    Electric resistivity, magnetic susceptibility, thermoelectric power, and Hall coefficient of Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y) whose onset temperature of the superconductivity are 24 K and 23 K were measured. Experimental results show many interesting features. In particular, the Hall coefficients are negative and relatively flat as a function of temperature. However, the temperature dependence of the thermoelectric power (TEP) for these two samples shows the positive sign for both samples in contrast to the previous results. Moreover TEP for both samples remains flat in the normal state below 250 K, but decreases rapidly above 250 K. TEP of only Pr(1.85)Ce(0.15)CuO(4-y) shows a peak near 50 K. Finally onset temperatures of sudden drop of TEP are higher than those of resistance drop. The physical properties of these samples produced at different conditions such as different heat treatment temperatures, atmospheres were also measured. TEP and resistance measurement show that oxygen deficiency is essential to produce better superconducting samples. Correlation between TEP and superconductivity for these different samples will be discussed.

  6. Influence of variable topsoil replacement depths on soil chemical parameters within a coal mine in northeastern Wyoming, USA

    SciTech Connect

    Schladweiler, B.K.; Vance, G.F.; Legg, D.E.; Munn, L.C.; Haroian, R.

    2004-10-15

    Uniform topsoil replacement depths on coal mine reclaimed areas have been mandated by USA federal and state regulations; however, soils of the premine landscape are not naturally uniform in depth and vary in physical, chemical, and biological characteristics. In addition, uniform topsoil depths may actually hinder the development of diverse reclaimed plant communities. We studied the effect of varying topsoil replacement depth treatments (15, 30, and 56 cm) on soil and backfill pH, electrolytic conductivity (EC), and sodium adsorption ratio (SAR) within a reclaimed coal mine study area. Backfill material (also known as spoil) at this site did not possess levels of pH, EC, and SAR that were detrimental to plant growth. There was only a slight reduction in pH, EC, and SAR within the upper 15 cm depth in the reclaimed topsoil treatments with a general increase of EC and SAR in the lower portion of the replaced soil profile. Some downward movement of soluble salts within the reclaimed treatments was evident despite low precipitation. For examples, SAR in the 0-15 cm depth over all reclaimed treatments was lower in 2002 than 2000-2001, and the 0-30 cm portion of the reclaimed soil profile had reduced pH and EC, while the 30-60 cm portion had increased EC and SAR. It is anticipated that soil quality differences in terms of pH, EC, and SAR between topsoil depth treatments will be enhanced with time. Comparison of the reclaimed area to the native reference areas suggested numerous depth differences as a result of homogeneity of the replaced topsoil vs. undisturbed soil profiles.

  7. Ganciclovir ophthalmic gel 0.15% for the treatment of acute herpetic keratitis: background, effectiveness, tolerability, safety, and future applications

    PubMed Central

    Chou, Timothy Y; Hong, Bennett Y

    2014-01-01

    Eye disease due to herpes simplex virus (HSV) is a leading cause of ocular morbidity and the number one infectious cause of unilateral corneal blindness in the developed parts of the globe. Recurrent keratitis can result in progressive corneal scarring, thinning, and vascularization. Antiviral agents employed against HSV have primarily been nucleoside analogs. Early generation drugs included idoxuridine, iododesoxycytidine, vidarabine, and trifluridine. While effective, they tended to have low bioavailability and measurable local cellular toxicity due to their nonselective mode of action. Acyclovir 0.3% ointment is a more selective agent, and had become a first-line topical drug for acute HSV keratitis in Europe and other places outside of the US. Ganciclovir 0.15% gel is the most recently approved topical treatment for herpes keratitis. Compared to acyclovir 0.3% ointment, ganciclovir 0.15% gel has been shown to be better tolerated and no less effective in several Phase II and III trials. Additionally, topical ganciclovir does not cause adverse systemic side effects and is therapeutic at lower concentrations. Based on safety, efficacy, and tolerability, ganciclovir 0.15% gel should now be considered a front-line topical drug in the treatment of dendritic herpes simplex epithelial keratitis. Topics of future investigation regarding other potential uses for ganciclovir gel may include the prophylaxis of recurrent HSV epithelial keratitis, treatment of other forms of ocular disease caused by herpesviruses and adenovirus, and ganciclovir gel as an adjunct to antitumor therapy. PMID:25187721

  8. A comprehensive investigation of structural, morphological, hydrogen absorption and magnetic properties of MmNi4.22Co0.48Mn0.15Al0.15 alloy

    NASA Astrophysics Data System (ADS)

    Zareii, Seyyed Mojtaba; Arabi, Hadi; Pourarian, Faiz

    2014-05-01

    A comprehensive study of structural, morphological, hydrogen absorption and magnetic properties of MmNi4.22 Co0.48Mn0.15Al0.15 alloy as a promising hydrogen storage media was investigated. The X-ray diffraction (XRD) profiles show that the alloy maintains its crystal structure (hexagonal LaNi5-type) even after 30 hydrogenation/dehydrogenation (H/D) cycles. However, the XRD peaks are found to be slightly broadened after cycling. SEM images reveal that particles size of the cycled sample decreases, with more uniform particle size distribution compared to noncycled ones. The pressure-composition (PC) isotherms and kinetics curves of hydrogen absorption reaction were obtained at different working temperatures by using a homemade Sievert apparatus. The enthalpy and entropy of hydride formation of the alloy were evaluated. Furthermore, the Jander diffusion and Johnson-Mehl-Avrami models as the fitting models were employed to study the kinetic mechanism of hydriding reaction and its activation energy. The room temperature magnetic measurements indicate that the milling and H/D cycling change the magnetic properties of the as-annealed alloy.

  9. Ramp-edge junctions between superconducting Nd1.85Ce0.15CuO4 and La1.85Sr0.15CuO4

    NASA Astrophysics Data System (ADS)

    Hoek, M.; Coneri, F.; Renshaw Wang, X.; Hilgenkamp, H.

    2016-03-01

    We have fabricated in-plane ramp-edge junctions between Nd1.85Ce0.15CuO4 (NCCO) and La1.85Sr0.15CuO4 (LSCO) where both layers are superconducting. At the interface, we find an insulating barrier in electronic transport. The barrier is shown to be a tunneling barrier with a combination of inelastic and elastic tunneling, the former is indicated by the appearance of the LSCO phonon density of states in {{{d}}}2I/{{d}}{V}2 measurements and the latter is inferred from the temperature dependence of the conductance. The energy scale of the barrier is smaller than would be expected from band alignment found by considering the cuprates as degenerate semiconductors. It is closest to the scenario where hybridization of the O 2p valence band states dictate band alignment. Additional experiments with overdoped interlayers of Nd1.8Ce0.2CuO4 and La1.75Sr0.25CuO4 show that the origin of the barrier is most likely a combination of electronic depletion mainly in the NCCO and a strain effect in the LSCO.

  10. Lithium-Rich Layered Oxide Li1.18 Ni0.15 Co0.15 Mn0.52 O2 as the Cathode Material for Hybrid Sodium-Ion Batteries.

    PubMed

    Wei, Zhixuan; Gao, Yu; Wang, Lei; Zhang, Chaoyang; Bian, Xiaofei; Fu, Qiang; Wang, Chunzhong; Wei, Yingjin; Du, Fei; Chen, Gang

    2016-08-01

    Li-rich layered oxide Li1.18 Ni0.15 Co0.15 Mn0.52 O2 (LNCM) is, for the first time, examined as the positive electrode for hybrid sodium-ion battery and its Na(+) storage properties are comprehensively studied in terms of galvanostatic charge-discharge curves, cyclic voltammetry and rate capability. LNCM in the proposed sodium-ion battery demonstrates good rate capability whose discharge capacity reaches about 90 mA h g(-1) at 10 C rate and excellent cycle stability with specific capacity of about 105 mA h g(-1) for 200 cycles at 5 C rate. Moreover, ex situ ICP-OES suggests interesting mixed-ions migration processes: In the initial two cycles, only Li(+) can intercalate into the LNCM cathode, whereas both Li(+) and Na(+) work together as the electrochemical cycles increase. Also the structural evolution of LNCM is examined in terms of ex situ XRD pattern at the end of various charge-discharge scans. The strong insight obtained from this study could be beneficial to the design of new layered cathode materials for future rechargeable sodium-ion batteries. PMID:27320123

  11. Low-temperature specific heat of magnetic superconductors Dy0.6Y0.4Rh3.85Ru0.15B4 and Dy0.6Y0.4Rh4B4

    NASA Astrophysics Data System (ADS)

    Terekhov, A. V.; Zolochevskii, I. V.; Ishchenko, L. A.; Zaleski, A.; Khlybov, E. P.; Lachenkov, S. A.

    2016-03-01

    Specific heat CM(T) of polycrystalline Dy0.6Y0.4Rh4B4 and Dy0.6Y0.4Rh3.85Ru0.15B4 was studied in the temperature range of 0.5-9 K and magnetic fields 0-10 kOe for the first time. It was found that the λ-anomaly in the specific heat exists at Tc ≈ 6 K for Dy0.6Y0.4Rh4B4 and at Tc ≈ 6.6 K for Dy0.6Y0.4Rh3.85Ru0.15B4. It is suppressed in a magnetic field and shifted to lower temperatures. Partial substitution of Rh by Ru enhances superconductivity, presumably, due to stronger inner magnetism of the dysprosium sublattice in Dy0.6Y0.4Rh4B4 as compared with Dy0.6Y0.4Rh3.85Ru0.15B4. Furthermore, it was observed that the molar heat capacity CM(T) of Dy0.6Y0.4Rh3.85Ru0.15B4 increases with decreasing temperature for T < 4 K. In Dy0.6Y0.4Rh4B4, an increase in CM(T) with decreasing temperature is accompanied by the appearance of a maximum at Tmax = 1.5 K, which might be a manifestation of the magnetic phase transition in the dysprosium subsystem at this temperature.

  12. Unusual magnetoresistance in cubic B20 Fe0.85Co0.15Si chiral magnets

    NASA Astrophysics Data System (ADS)

    Huang, S. X.; Chen, Fei; Kang, Jian; Zang, Jiadong; Shu, G. J.; Chou, F. C.; Chien, C. L.

    2016-06-01

    The B20 chiral magnets with broken inversion symmetry and C4 rotation symmetry have attracted much attention. The broken inversion symmetry leads to the Dzyaloshinskii–Moriya that gives rise to the helical and Skyrmion states. We report the unusual magnetoresistance (MR) of B20 chiral magnet Fe0.85Co0.15Si that directly reveals the broken C4 rotation symmetry and shows the anisotropic scattering by Skyrmions with respect to the current directions. The intimacy between unusual MR and broken symmetry is well confirmed by theoretically studying an effective Hamiltonian with spin–orbit coupling. The unusual MR serves as a transport signature for the Skyrmion phase.

  13. PAPER-64 Constraints on Reionization: The 21 cm Power Spectrum at z = 8.4

    NASA Astrophysics Data System (ADS)

    Ali, Zaki S.; Parsons, Aaron R.; Zheng, Haoxuan; Pober, Jonathan C.; Liu, Adrian; Aguirre, James E.; Bradley, Richard F.; Bernardi, Gianni; Carilli, Chris L.; Cheng, Carina; DeBoer, David R.; Dexter, Matthew R.; Grobbelaar, Jasper; Horrell, Jasper; Jacobs, Daniel C.; Klima, Pat; MacMahon, David H. E.; Maree, Matthys; Moore, David F.; Razavi, Nima; Stefan, Irina I.; Walbrugh, William P.; Walker, Andre

    2015-08-01

    In this paper, we report new limits on 21 cm emission from cosmic reionization based on a 135 day observing campaign with a 64-element deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization in South Africa. This work extends the work presented in Parsons et al. with more collecting area, a longer observing period, improved redundancy-based calibration, improved fringe-rate filtering, and updated power-spectral analysis using optimal quadratic estimators. The result is a new 2σ upper limit on Δ2(k) of (22.4 mK)2 in the range 0.15\\lt k\\lt 0.5h {{Mpc}}-1 at z = 8.4. This represents a three-fold improvement over the previous best upper limit. As we discuss in more depth in a forthcoming paper, this upper limit supports and extends previous evidence against extremely cold reionization scenarios. We conclude with a discussion of implications for future 21 cm reionization experiments, including the newly funded Hydrogen Epoch of Reionization Array.

  14. Remarkable magnetostructural coupling around the magnetic transition in CeCo0.85Fe0.15Si

    NASA Astrophysics Data System (ADS)

    Correa, V. F.; Betancourth, D.; Sereni, J. G.; Caroca Canales, N.; Geibel, C.

    2016-09-01

    We report a detailed study of the magnetic properties of CeCo0.85Fe0.15Si under high magnetic fields (up to 16 Tesla) measuring different physical properties such as specific heat, magnetization, electrical resistivity, thermal expansion and magnetostriction. CeCo0.85Fe0.15Si becomes antiferromagnetic at {{T}N}≈ 6.7 K. However, a broad tail (onset at {{T}X}≈ 13 K) in the specific heat precedes that second order transition. This tail is also observed in the temperature derivative of the resistivity. However, it is particularly noticeable in the thermal expansion coefficient where it takes the form of a large bump centered at T X . A high magnetic field practically washes out that tail in the resistivity. But surprisingly, the bump in the thermal expansion coefficient becomes a well pronounced peak fully split from the magnetic transition at T N . Concurrently, the magnetoresistance also switches from negative to positive above T N . The magnetostriction is considerable and irreversible at low temperature (\\frac{Δ L}{L}(16~T)∼ 4× {{10}-4} at 2 K) when the magnetic interactions dominate. A broad jump in the field dependence of the magnetostriction observed at low T may be the signature of a weak ongoing metamagnetic transition. Taking altogether the results indicate the importance of the lattice effects on the development of the magnetic order in these alloys.

  15. A 0.15-scale study of configuration effects on the aerodynamic interaction between main rotor and fuselage

    NASA Technical Reports Server (NTRS)

    Trept, Ted

    1984-01-01

    Hover and forward flight tests were conducted to investigate the mutual aerodynamic interaction between the main motor and fuselage of a conventional helicopter configuration. A 0.15-scale Model 222 two-bladed teetering rotor was combined with a 0.15-scale model of the NASA Ames 40x80-foot wind tunnel 1500 horsepower test stand fairing. Configuration effects were studied by modifying the fairing to simulate a typical helicopter forebody. Separation distance between rotor and body were also investigated. Rotor and fuselage force and moment as well as pressure data are presented in graphical and tabular format. Data was taken over a range of thrust coefficients from 0.002 to 0.007. In forward flight speed ratio was varied from 0.1 to 0.3 with shaft angle varying from +4 to -12 deg. The data show that the rotors effect on the fuselage may be considerably more important to total aircraft performance than the effect of the fuselage on the rotor.

  16. Remarkable magnetostructural coupling around the magnetic transition in CeCo0.85Fe0.15Si.

    PubMed

    Correa, V F; Betancourth, D; Sereni, J G; Caroca Canales, N; Geibel, C

    2016-09-01

    We report a detailed study of the magnetic properties of CeCo0.85Fe0.15Si under high magnetic fields (up to 16 Tesla) measuring different physical properties such as specific heat, magnetization, electrical resistivity, thermal expansion and magnetostriction. CeCo0.85Fe0.15Si becomes antiferromagnetic at [Formula: see text] K. However, a broad tail (onset at [Formula: see text] K) in the specific heat precedes that second order transition. This tail is also observed in the temperature derivative of the resistivity. However, it is particularly noticeable in the thermal expansion coefficient where it takes the form of a large bump centered at T X . A high magnetic field practically washes out that tail in the resistivity. But surprisingly, the bump in the thermal expansion coefficient becomes a well pronounced peak fully split from the magnetic transition at T N . Concurrently, the magnetoresistance also switches from negative to positive above T N . The magnetostriction is considerable and irreversible at low temperature ([Formula: see text] at 2 K) when the magnetic interactions dominate. A broad jump in the field dependence of the magnetostriction observed at low T may be the signature of a weak ongoing metamagnetic transition. Taking altogether the results indicate the importance of the lattice effects on the development of the magnetic order in these alloys. PMID:27357448

  17. Depth keying

    NASA Astrophysics Data System (ADS)

    Gvili, Ronen; Kaplan, Amir; Ofek, Eyal; Yahav, Giora

    2003-05-01

    We present a new solution to the known problem of video keying in a natural environment. We segment foreground objects from background objects using their relative distance from the camera, which makes it possible to do away with the use of color for keying. To do so, we developed and built a novel depth video camera, capable of producing RGB and D signals, where D stands for the distance to each pixel. The new RGBD camera enables the creation of a whole new gallery of effects and applications such as multi-layer background substitutions. This new modality makes the production of real time mixed reality video possible, as well as post-production manipulation of recorded video. We address the problem of color spill -- in which the color of the foreground object is mixed, along its boundary, with the background color. This problem prevents an accurate separation of the foreground object from its background, and it is most visible when compositing the foreground objects to a new background. Most existing techniques are limited to the use of a constant background color. We offer a novel general approach to the problem with enabling the use of the natural background, based upon the D channel generated by the camera.

  18. Implication of Land Use and Belowground Weather on Nitrous Oxide Soil Depth Profiles and Denitrification Potential

    NASA Astrophysics Data System (ADS)

    Phillips, R. L.; Song, B.; Saliendra, N.; Liebig, M. A.

    2013-12-01

    Agricultural soils are the largest single source of anthropogenic nitrous oxide (N2O) to the atmosphere, which is largely attributed to the expansion in the use of synthetic fertilizer nitrogen (N). Alfalfa crops often do not require synthetic N addition because N is fixed symbiotically belowground. Some biologically fixed N leaks into soil, which could affect production and consumption of N2O. While many studies have reported net fluxes of N2O at the soil surface, few have quantified variation in N2O concentration at multiple soil depths under variable climatic conditions without synthetic N inputs. A no-till crop field, seeded to alfalfa (Medicago sativa) in 2009, was compared to neighboring native prairie in North Dakota, U.S.A. to determine if N2O, CO2 and CH4 concentrations varied with depth between fields for 4 years. Both fields (> 15 ha) were harvested for hay without N-fertilizer inputs between 2009 and 2013. Soils and instrumentation were similar. Sensors and soil gas well collection chambers were buried at near-surface (15 and 30 cm) and sub-surface (60 and 90 cm) soil depths. Temperature, moisture, oxygen, relative humidity, and pressure data were collected every 30 minutes, and gas well concentration data were collected twice weekly until spring 2013. Cores were collected for each depth increment in 2012, and potential rates of denitrification and anammox were measured for the 0-15 cm depth using soil slurry incubation experiments with 15N tracer treatments. We evaluated temporal variability in N2O concentration with depth and found N2O spikes beneath alfalfa tended to be an order of magnitude higher and more persistent than N2O peaks beneath prairie. Median N2O concentrations at sub-surface depths were greater than near-surface depths. Alfalfa median N2O concentrations for near-surface (24 nmols N2O L-1) and sub-soils (30 nmols N2O L-1) were higher than N2O concentrations beneath prairie (15 nmols N2O L-1 and 17 nmols N2O L-1, respectively). Soil

  19. An AlN/Al0.85Ga0.15N high electron mobility transistor

    NASA Astrophysics Data System (ADS)

    Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.; Douglas, Erica A.; Sanchez, Carlos A.; King, Michael P.; Coltrin, Michael E.; Fortune, Torben R.; Kaplar, Robert J.

    2016-07-01

    An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al0.85Ga0.15N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high Ion/Ioff current ratio greater than 107 and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. The room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.

  20. Unusual magnetoresistance in cubic B20 Fe0.85Co0.15Si chiral magnets

    DOE PAGESBeta

    Huang, S. X.; Chen, Fei; Kang, Jian; Zang, Jiadong; Shu, G. J.; Chou, F. C.; Chien, C. L.

    2016-06-24

    The B20 chiral magnets with broken inversion symmetry and C4 rotation symmetry have attracted much attention. The broken inversion symmetry leads to the Dzyaloshinskii–Moriya that gives rise to the helical and Skyrmion states.Wereport the unusual magnetoresistance (MR) of B20 chiral magnet Fe0.85Co0.15Si that directly reveals the broken C4 rotation symmetry and shows the anisotropic scattering by Skyrmions with respect to the current directions. The intimacy between unusual MR and broken symmetry is well confirmed by theoretically studying an effective Hamiltonian with spin–orbit coupling. In conclusion, the unusual MR serves as a transport signature for the Skyrmion phase.

  1. The ferroelectricity in perovskite K0.85Ba0.15TaO3+0.075 nanocrystallites

    NASA Astrophysics Data System (ADS)

    Shang, Mingyu; Xu, Chong; Chen, Yan; Ding, Qingfeng; Yuan, Hongming; Sun, Fengyue; Feng, Shouhua

    2015-08-01

    The perovskite K0.85Ba0.15TaO3+0.075 nanocrystallites have been synthesized by mild hydrothermal method for the first time. The powder X-ray diffraction analysis indicates that the crystallographic structure is a primitive cubic, space group Pm-3m with a unit cell edge a=4.00 Å. Heavily Ba doped in K-site was achieved in the perovskite structure with excess oxygen to balance the charge. The chemical substitution changes the crystal structure and electronic structure of KTaO3, which has an impact on its polarization property and induce a ferroelectric phase. The temperature-dependent dielectric response from 300 K to 600 K and hysteresis loop at 300 K provide direct evidence for the ferroelectric character. Its Curie temperature has been obtained from relative dielectric and thermal analysis (TC=460 K).

  2. Nonlinear structure-composition relationships in the Ge1-ySny/Si(100) (y<0.15) system

    DOE PAGESBeta

    Beeler, R.; Roucka, R.; Chizmeshya, A. V. G.; Kouvetakis, J.; Menéndez, J.

    2011-07-26

    The compositional dependence of the cubic lattice parameter in Ge1-ySny alloys has been revisited. Large 1000-atom supercell ab initio simulations confirm earlier theoretical predictions that indicate a positive quadratic deviation from Vegard's law, albeit with a somewhat smaller bowing coefficient, θ = 0.047 Å, than found from 64-atom cell simulations (θ = 0.063 Å). On the other hand, measurements from an extensive set of alloy samples with compositions y < 0.15 reveal a negative deviation from Vegard's law. The discrepancy with earlier experimental data, which supported the theoretical results, is traced back to an unexpected compositional dependence of the residualmore » strain after growth on Si substrates. The experimental bowing parameter for the relaxed lattice constant of the alloys is found to be θ = -0.066 Å. Possible reasons for the disagreement between theory and experiment are discussed in detail.« less

  3. Citrate-complexation synthesized Ce0.85Gd0.15O2-δ (GDC15) as solid electrolyte for intermediate temperature SOFC

    NASA Astrophysics Data System (ADS)

    Anjaneya, K. C.; Manjanna, J.; Nayaka, G. P.; Ashwin Kumar, V. M.; Govindaraj, G.; Ganesha, K. N.

    2014-08-01

    A typical Ce0.85Gd0.15O2-δ (GDC15) composition of CeO2-Gd2O3 system is synthesized by modified sol-gel technique known as citrate-complexation. TG-DTA, XRD, FT-IR, Raman, FE-SEM/EDX and ac-impedance analysis are carried out for structural and electrical characterization. XRD pattern confirmed the well crystalline cubic fluorite structure of GDC15 after calcining at 873 K. Raman spectral bands at 463, 550 and 600 cm-1 are also in agreement with these structural features. FE-SEM image shows well-defined grains separated from grain boundary and good densification. Ac-impedance studies reveal that GDC15 has oxide ionic conductivity similar to that reported for Ce0.9Gd0.1O2-δ (GDC10) and Ce0.8Gd0.2O2-δ (GDC20). Ionic and electronic transference numbers at 673 K are found to be 0.95 and 0.05, respectively. This indicates the possible application of GDC15 as a potential electrolyte for IT-SOFCs.

  4. Highly Reliable 0.15 μm/14 F2 Cell Ferroelectric Random Access Memory Capacitor Using SrRuO3 Buffer Layer

    NASA Astrophysics Data System (ADS)

    Heo, Jang‑Eun; Bae, Byoung‑Jae; Yoo, Dong‑Chul; Nam, Sang‑Don; Lim, Ji‑Eun; Im, Dong‑Hyun; Joo, Suk‑Ho; Jung, Yong‑Ju; Choi, Suk‑Hun; Park, Soon‑Oh; Kim, Hee‑Seok; Chung, U‑In; Moon, Joo‑Tae

    2006-04-01

    We investigated a novel technique of modifying the interface between a Pb(ZrxTi1-x)O3 (PZT) thin film and electrodes for high density 64 Mbit ferroelectric random access memory (FRAM) device. Using a SrRuO3 buffer layer, we successfully developed highly reliable 0.15 μm/14 F2 cell FRAM capacitors with 75-nm-thick polycrystalline PZT thin films. The SrRuO3 buffer layer greatly enhanced ferroelectric characteristics due to the decrease in interfacial defect density. In PZT capacitors with a total thickness of 180 nm for whole capacitor stack, a remnant polarization of approximately 42 μC/cm2 was measured with a 1.4 V operation. In addition, an opposite state remnant polarization loss of less than 15% was observed after baking at 150 °C for 100 h. In particular, we found that the SrRuO3 buffer layer also played a key role in inhibiting the diffusion of Pb and O from the PZT thin films.

  5. Sound velocities of bcc-Fe and Fe0.85Si0.15 alloy at high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Liu, Jin; Lin, Jung-Fu; Alatas, Ahmet; Bi, Wenli

    2014-08-01

    Studying the velocity-density profiles of iron and iron-silicon alloy at high pressures and temperatures is critical for understanding the Earth’s core as well as the interiors of other planetary bodies. Here we have investigated the compressional wave velocity (VP) and density (ρ) profiles of polycrystalline bcc-Fe and Fe0.85Si0.15 alloy (8 wt.% Si) using in situ high-energy resolution inelastic X-ray scattering (HERIX) and synchrotron X-ray diffraction spectroscopies in an externally-heated diamond anvil cell (EHDAC) up to 15 GPa and 700 K. Based on the measured velocity-density (VP-ρ) and velocity-pressure (VP-P) relations of bcc-Fe at simultaneous high pressure and temperature (P-T) conditions, our results show a strong VP reduction at elevated temperatures at a constant density. Comparison of the VP-ρ profiles between the bcc-Fe and bcc-Fe0.85Si0.15 alloy indicates that the alloying effect of additional 8 wt.% Si on the VP-ρ relationship of bcc-Fe is predominant via a constant density decrease of approximately 0.6 g/cm3 (7%). Compared with the literature velocity results for bcc and hcp Fe-Si alloys, the bcc-Fe and Fe-Si alloys exhibit higher VP than their hcp phase counterparts at the given bcc-hcp transition pressures. Our results here strongly support the notion that high temperature has a strong effect on the VP of Fe and that the VP-ρ profile of Fe can be affected by structural and magnetic transitions. Analyses on literature elastic constants of the bcc Fe-Si alloys, as a function of P-T and Si content, show that the bcc phase displays extremely high VP anisotropy of 16-30% and VS splitting anisotropy of 40-90% at high temperatures, while the addition of Si further enhances the anisotropy. Due to the extremely high elastic anisotropy of the bcc Fe-Si alloy, a certain portion of the bcc Fe-Si alloy with the lattice-preferred orientation may produce VP and VS anisotropies to potentially account for the observed seismic anisotropy in the inner core.

  6. Serpentine Nanotubes in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Dodony, Istvan; Buseck, Peter R.

    2004-01-01

    The CM chondrites are primitive meteorites that formed during the early solar system. Although they retain much of their original physical character, their matrices and fine-grained rims (FGRs) sustained aqueous alteration early in their histories [1- 3]. Serpentine-group minerals are abundant products of such alteration, and information regarding their structures, compositions, and spatial relationships is important for determining the reactions that produced them and the conditions under which they formed. Our recent work on FGRs and matrices of the CM chondrites has revealed new information on the structures and compositions of serpentine-group minerals [4,5] and has provided insights into the evolution of these primitive meteorites. Here we report on serpentine nanotubes from the Mighei and Murchison CM chondrites [6].

  7. Variation of the lunar highland surface roughness at baseline 0.15-100 km and the relationship to relative age

    NASA Astrophysics Data System (ADS)

    Yokota, Y.; Gwinner, K.; Oberst, J.; Haruyama, J.; Matsunaga, T.; Morota, T.; Noda, H.; Araki, H.; Ohtake, M.; Yamamoto, S.; Gläser, P.; Ishihara, Y.; Honda, C.; Hirata, N.; Demura, H.

    2014-03-01

    We report the surface roughness analysis of the lunar highlands for the baseline range 0.15-100 km. We use the Median Differential Slope αm to investigate the scale dependency of the roughness and derive the global αm distribution from SELENE Laser Altimeter and Terrain Camera data. While αm(l) versus baseline l (km) plots vary among different highland types, all highlands commonly show a peak at 3-30 km. The Pre-Nectarian surface shows a relatively large αm(20-30 km). Our analysis is supported by the simulation of synthetic surface cratering models and crater statistics. In our simulation, a peak of αm(30 km) is successfully reproduced. The actual crater density shows good correlation with an empirical roughness indicator. However, a large part of the Nectarian surface shows a peak at 6-9 km baseline. This peak may be caused by secondary craters and ejecta deposit textures from the Nectarian system basins.

  8. 344 cm x 86 cm low mass vacuum window

    SciTech Connect

    Reimers, R.M.; Porter, J.; Meneghetti, J.; Wilde, S.; Miller, R.

    1983-08-01

    The LBL Heavy Ion Spectrometer System (HISS) superconducting magnet contains a 1 m x 3.45 m x 2 m vacuum tank in its gap. A full aperture thin window was needed to minimize background as the products of nuclear collisions move from upstream targets to downstream detectors. Six windows were built and tested in the development process. The final window's unsupported area is 3m/sup 2/ with a 25 cm inward deflection. The design consists of a .11 mm Nylon/aluminum/polypropylene laminate as a gas seal and .55 mm woven aramid fiber for strength. Total mass is 80 milligrams per cm/sup 2/. Development depended heavily on past experience and testing. Safety considerations are discussed.

  9. Detecting the 21 cm forest in the 21 cm power spectrum

    NASA Astrophysics Data System (ADS)

    Ewall-Wice, Aaron; Dillon, Joshua S.; Mesinger, Andrei; Hewitt, Jacqueline

    2014-07-01

    We describe a new technique for constraining the radio-loud population of active galactic nuclei at high redshift by measuring the imprint of 21 cm spectral absorption features (the 21 cm forest) on the 21 cm power spectrum. Using semi-numerical simulations of the intergalactic medium and a semi-empirical source population, we show that the 21 cm forest dominates a distinctive region of k-space, k ≳ 0.5 Mpc- 1. By simulating foregrounds and noise for current and potential radio arrays, we find that a next-generation instrument with a collecting area of the order of ˜ 0.1 km2 (such as the Hydrogen Epoch of Reionization Array) may separately constrain the X-ray heating history at large spatial scales and radio-loud active galactic nuclei of the model we study at small ones. We extrapolate our detectability predictions for a single radio-loud active galactic nuclei population to arbitrary source scenarios by analytically relating the 21 cm forest power spectrum to the optical depth power spectrum and an integral over the radio luminosity function.

  10. BACE0.85Y0.15O3-DELTA Based Materials for Inovative Monolithic Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Krezhov, Kiril; Vladikova, Daria

    2016-07-01

    Solid oxide fuel cells (SOFCs) offer a promising green technology of direct conversion of chemical energy of fuel into electricity. Among the families of metal oxides, which can be successfully used as electrodes (cathodes or anodes) in SOFC, certain members of the large family of transition-metal oxides with perovskite structure ABO _{3} were found very prospective to fulfil most of the features required for preparation of mixed ionic-electronic conductor (MIEC) oxide materials for SOFCs operated in the intermediate temperature range. In this regard Barium cerate with Y-substitution at the B-site (Ce site) is well known for excellent conduction capabilities in the temperature range 400-800 °C as a result from the proton motion in the crystal lattice. Doping with Y ^{3+} is very effective and the proton conductivity in BaCe _{1-x}Y _{x}O _{3-δ} increases with the increasing of the dopant concentration up to x =0.2. However, the phase behaviour of the composition BCY20 (x=0.20) is very complicated. Even at room temperature the crystalline structure remains contradictory because various structures of monoclinic, rhombohedral and orthorhombic symmetry are reported. The characterization of the chemical composition and stability, oxygen stoichiometry and cationic ratios of each synthesized phase is of great importance to understand the defect-chemistry that would govern the transport properties. We report on oxygen-deficient BaCe _{0.85}Y _{0.15}O _{3-δ} (BCY15) perovskites prepared by auto-combustion with following calcination at high temperature. The structural details of powder, dense and porous samples of materials based on BCY15 were investigated from full profile analysis of neutron and x-ray diffraction patterns. The materials were used recently as cathode, anode and central membrane in an innovative monolithic design of SOFC.

  11. Stereo depth distortions in teleoperation

    NASA Technical Reports Server (NTRS)

    Diner, Daniel B.; Vonsydow, Marika

    1988-01-01

    In teleoperation, a typical application of stereo vision is to view a work space located short distances (1 to 3m) in front of the cameras. The work presented here treats converged camera placement and studies the effects of intercamera distance, camera-to-object viewing distance, and focal length of the camera lenses on both stereo depth resolution and stereo depth distortion. While viewing the fronto-parallel plane 1.4 m in front of the cameras, depth errors are measured on the order of 2cm. A geometric analysis was made of the distortion of the fronto-parallel plane of divergence for stereo TV viewing. The results of the analysis were then verified experimentally. The objective was to determine the optimal camera configuration which gave high stereo depth resolution while minimizing stereo depth distortion. It is found that for converged cameras at a fixed camera-to-object viewing distance, larger intercamera distances allow higher depth resolutions, but cause greater depth distortions. Thus with larger intercamera distances, operators will make greater depth errors (because of the greater distortions), but will be more certain that they are not errors (because of the higher resolution).

  12. AMR on the CM-2

    NASA Technical Reports Server (NTRS)

    Berger, Marsha J.; Saltzman, Jeff S.

    1992-01-01

    We describe the development of a structured adaptive mesh algorithm (AMR) for the Connection Machine-2 (CM-2). We develop a data layout scheme that preserves locality even for communication between fine and coarse grids. On 8K of a 32K machine we achieve performance slightly less than 1 CPU of the Cray Y-MP. We apply our algorithm to an inviscid compressible flow problem.

  13. Cardiovascular rhythms in the 0.15-Hz band: common origin of identical phenomena in man and dog in the reticular formation of the brain stem?

    PubMed

    Perlitz, Volker; Lambertz, Manfred; Cotuk, Birol; Grebe, Reinhard; Vandenhouten, Ralf; Flatten, Guido; Petzold, Ernst Richard; Schmid-Schönbein, Holger; Langhorst, Peter

    2004-09-01

    Selected examples from experiments in humans and dogs with time series of reticular neurons, respiration, arterial blood pressure and cutaneous forehead blood content fluctuations were analysed using multiscaled time-frequency distribution, post-event-scan and pointwise transinformation. We found in both experiments a "0.15-Hz rhythm" exhibiting periods of spindle waves (increasing and decreasing amplitudes), phase synchronized with respiration at 1:2 and 1:1 integer number ratios. At times of wave-epochs and n:m phase synchronization, the 0.15-Hz rhythm appeared in heart rate and arterial blood pressure. As phase synchronization of the 0.15-Hz rhythm with respiration was established at a 1:1 integer number ratio, all cardiovascular-respiratory oscillations were synchronized at 0.15 Hz. Analysis of a canine experiment supplied evidence that the emergence of the 0.15-Hz rhythm and n:m phase synchronization appears to result from a decline in the level of the general activity of the organism associated with a decline in the level of activity of reticular neurons in the lower brainstem network. These findings corroborate the notion of the 0.15-Hz rhythm as a marker of the "trophotropic mode of operation" first introduced by W.R. Hess. PMID:15138824

  14. Detailed modelling of the 21-cm forest

    NASA Astrophysics Data System (ADS)

    Semelin, B.

    2016-01-01

    The 21-cm forest is a promising probe of the Epoch of Reionization. The local state of the intergalactic medium (IGM) is encoded in the spectrum of a background source (radio-loud quasars or gamma-ray burst afterglow) by absorption at the local 21-cm wavelength, resulting in a continuous and fluctuating absorption level. Small-scale structures (filaments and minihaloes) in the IGM are responsible for the strongest absorption features. The absorption can also be modulated on large scales by inhomogeneous heating and Wouthuysen-Field coupling. We present the results from a simulation that attempts to preserve the cosmological environment while resolving some of the small-scale structures (a few kpc resolution in a 50 h-1 Mpc box). The simulation couples the dynamics and the ionizing radiative transfer and includes X-ray and Lyman lines radiative transfer for a detailed physical modelling. As a result we find that soft X-ray self-shielding, Ly α self-shielding and shock heating all have an impact on the predicted values of the 21-cm optical depth of moderately overdense structures like filaments. A correct treatment of the peculiar velocities is also critical. Modelling these processes seems necessary for accurate predictions and can be done only at high enough resolution. As a result, based on our fiducial model, we estimate that LOFAR should be able to detect a few (strong) absorptions features in a frequency range of a few tens of MHz for a 20 mJy source located at z = 10, while the SKA would extract a large fraction of the absorption information for the same source.

  15. Optical Characterization and 2,525 micron Lasing of Cr(2+):Cd(0.85)Mn(0.15)Te

    NASA Technical Reports Server (NTRS)

    Davis, V. R.; Wu, X.; Hoemmerich, U.; Trivedi, S. B.; Grasza, K.; Yu, Z.

    1997-01-01

    static acentric electric crystal field or the coupling of asymmetric phonons can force electric-dipole transitions by the admixture of wave functions with opposite parity. Tetrahedral sites lack inversion symmetry which provides the odd-parity field necessary to relax the parity selection rule. Therefore, high absorption and emission cross sections are observed. An enhanced radiative emission rate is also expected to reduce the detrimental effect of non-radiative decay. Motivated by the initial results on Cr doped ZnS and ZnSe, we have started a comprehensive effort to study Cr(2+) doped II-VI semiconductors for solid-state laser applications. In this paper we present the optical properties and the demonstration of mid-infrared lasing from Cr doped Cd(0.85)Mn(0.15)Te.

  16. Thermoelectric Properties of Cu-Doped n-Type Bi2Te2.85Se0.15 Prepared by Liquid Phase Growth Using a Sliding Boat

    NASA Astrophysics Data System (ADS)

    Kitagawa, Hiroyuki; Matsuura, Tsukasa; Kato, Toshihito; Kamata, Kin-ya

    2015-06-01

    N-type Bi2Te2.85Se0.15 thermoelectric materials were prepared by liquid phase growth (LPG) using a sliding boat, a simple and short fabrication process for Bi2Te3-related materials. Cu was selected as a donor dopant, and its effect on thermoelectric properties was investigated. Thick sheets and bars of Cu x Bi2 Te2.85Se0.15 ( x=0-0.25) of 1-2mm in thickness were obtained using the process. X-ray diffraction patterns and scanning electron micrographs showed that the in-plane direction tended to correspond to the hexagonal c-plane, which is the preferred direction for thermoelectric conversion. Cu-doping was effective in controlling conduction type and carrier (electron) concentration. The conduction type was p-type for undoped Bi2Te2.85Se0.15 and became n-type after Cu-doping. The Hall carrier concentration was increased by Cu-doping. Small resistivity was achieved in Cu0.02Bi2Te2.85Se0.15 owing to an optimized amount of Cu-doping and high crystal orientation. As a result, the maximum power factor near 310K for Cu0.02Bi2Te2.85Se0.15 was approximately 4×10-3W/K2m and had good reproducibility. Furthermore, the thermal stability of Cu0.02Bi2Te2.85Se0.15 was also confirmed by thermal cycling measurements of electrical resistivity. Thus, n-type Bi2Te2.85Se0.15 with a large power factor was prepared using the present LPG process.

  17. On the accretion process in a high-mass star forming region. A multitransitional THz Herschel-HIFI study of ammonia toward G34.26+0.15

    NASA Astrophysics Data System (ADS)

    Hajigholi, M.; Persson, C. M.; Wirström, E. S.; Black, J. H.; Bergman, P.; Olofsson, A. O. H.; Olberg, M.; Wyrowski, F.; Coutens, A.; Hjalmarson, Å.; Menten, K. M.

    2016-01-01

    Aims: Our aim is to explore the gas dynamics and the accretion process in the early phase of high-mass star formation. Methods: The inward motion of molecular gas in the massive star forming region G34.26+0.15 is investigated by using high-resolution profiles of seven transitions of ammonia at THz frequencies observed with Herschel-HIFI. The shapes and intensities of these lines are interpreted in terms of radiative transfer models of a spherical, collapsing molecular envelope. An accelerated Lambda Iteration (ALI) method is used to compute the models. Results: The seven ammonia lines show mixed absorption and emission with inverse P-Cygni-type profiles that suggest infall onto the central source. A trend toward absorption at increasingly higher velocities for higher excitation transitions is clearly seen in the line profiles. The J = 3 ← 2 lines show only very weak emission, so these absorption profiles can be used directly to analyze the inward motion of the gas. This is the first time a multitransitional study of spectrally resolved rotational ammonia lines has been used for this purpose. Broad emission is, in addition, mixed with the absorption in the 10-00 ortho-NH3 line, possibly tracing a molecular outflow from the star forming region. The best-fitting ALI model reproduces the continuum fluxes and line profiles, but slightly underpredicts the emission and absorption depth in the ground-state ortho line 10-00. An ammonia abundance on the order of 10-9 relative to H2 is needed to fit the profiles. The derived ortho-to-para ratio is approximately 0.5 throughout the infalling cloud core similar to recent findings for translucent clouds in sight lines toward W31C and W49N. We find evidence of two gas components moving inwards toward the central region with constant velocities: 2.7 and 5.3 km s-1, relative to the source systemic velocity. Attempts to model the inward motion with a single gas cloud in free-fall collapse did not succeed. Herschel is an ESA space

  18. Dielectric and ferroelectric properties of Ba(Sn{sub 0.15}Ti{sub 0.85})O{sub 3} thin films grown by a sol-gel process

    SciTech Connect

    Zhai Jiwei; Shen Bo; Yao Xi; Zhang Liangying

    2004-09-01

    Ferroelectric Ba(Sn{sub 0.15}Ti{sub 0.85})O{sub 3} (BTS) thin films were deposited on LaNiO{sub 3}-coated silicon substrates via a sol-gel process. Films showed a strong (1 0 0) preferred orientation depending upon annealing temperature and concentration of the precursor solution. The dependence of dielectric and ferroelectric properties on film orientation has been studied. The leakage current density of thin films at 100 kV/cm was 7 x 10{sup -7} A/cm{sup 2} and 5 x 10{sup -5} A/cm{sup 2} and their capacitor tunability was 54 and 25% at an applied field of 200 kV/cm (measurement frequency of 1 MHz) for the thin films deposited with 0.1 and 0.4 M spin-on solution, respectively. This work clearly reveals the highly promising potential of BTS compared with BST films for application in tunable microwave devices.

  19. GIANT METREWAVE RADIO TELESCOPE DETECTION OF TWO NEW H I 21 cm ABSORBERS AT z ≈ 2

    SciTech Connect

    Kanekar, N.

    2014-12-20

    I report the detection of H I 21 cm absorption in two high column density damped Lyα absorbers (DLAs) at z ≈ 2 using new wide-band 250-500 MHz receivers on board the Giant Metrewave Radio Telescope. The integrated H I 21 cm optical depths are 0.85 ± 0.16 km s{sup –1} (TXS1755+578) and 2.95 ± 0.15 km s{sup –1} (TXS1850+402). For the z = 1.9698 DLA toward TXS1755+578, the difference in H I 21 cm and C I profiles and the weakness of the radio core suggest that the H I 21cm absorption arises toward radio components in the jet, and that the optical and radio sightlines are not the same. This precludes an estimate of the DLA spin temperature. For the z = 1.9888 DLA toward TXS1850+402, the absorber covering factor is likely to be close to unity, as the background source is extremely compact, with the entire 5 GHz emission arising from a region of ≤ 1.4 mas in size. This yields a DLA spin temperature of T{sub s} = (372 ± 18) × (f/1.0) K, lower than typical T{sub s} values in high-z DLAs. This low spin temperature and the relatively high metallicity of the z = 1.9888 DLA ([Zn/H] =(– 0.68 ± 0.04)) are consistent with the anti-correlation between metallicity and spin temperature that has been found earlier in damped Lyα systems.

  20. GaP ring-like nanostructures on GaAs (100) with In{sub 0.15}Ga{sub 0.85}As compensation layers

    SciTech Connect

    Prongjit, Patchareewan Pankaow, Naraporn Boonpeng, Poonyasiri Thainoi, Supachok Panyakeow, Somsak Ratanathammaphan, Somchai

    2013-12-04

    We present the fabrication of GaP ring-like nanostructures on GaAs (100) substrates with inserted In{sub 0.15}Ga{sub 0.85}As compensation layers. The samples are grown by droplet epitaxy using solid-source molecular beam epitaxy. The dependency of nanostructural and optical properties of GaP nanostructures on In{sub 0.15}Ga{sub 0.85}As layer thickness is investigated by ex-situ atomic force microscope (AFM) and photoluminescence (PL). It is found that the characteristics of GaP ring-like structures on GaAs strongly depend on the In{sub 0.15}Ga{sub 0.85}As layer thickness.

  1. Consistent proportional increments in responses of belowground net primary productivity to long-term warming and clipping at various soil depths in a tallgrass prairie.

    PubMed

    Xu, Xia; Luo, Yiqi; Shi, Zheng; Zhou, Xuhui; Li, Dejun

    2014-03-01

    Root distribution patterns in soil are critical to understanding the interactions between climate and vegetation. However, it is not clear how climate change and land use practices affect belowground net primary productivity (BNPP) at various soil depths. In order to explore the effects of warming and clipping on root-distribution patterns along soil profile (0-15, 15-30, and 30-45 cm), we conducted a field experiment from 2005 to 2010 in a tallgrass prairie. We used infrared heaters to elevate soil temperature by approximately 2 °C and annual clipping to mimic hay harvest. Results showed that roots were not evenly distributed through the soil profile. On average across treatments and years, 53 and 83% of the BNPP to 45 cm was distributed in the top 15- and 30-cm soil layers, respectively. Warming- and clipping-induced increases in BNPP were distributed to different soil depths at the proportions similar to those of BNPP. The proportional distribution of BNPP at various soil depths to total BNPP (0-45 cm) was little affected by warming, clipping, and their interactions, resulting in non-significant changes in the distribution of BNPP through the soil profile. These findings suggest that the proportionally vertical distribution of BNPP may remain stable even when the amount of BNPP changes simultaneously in response to climate change and land use practices. PMID:24241643

  2. Strain-relaxation and critical thickness of epitaxial La1.85Sr0.15CuO4 films

    DOE PAGESBeta

    Meyer, Tricia L; Jiang, Lu; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2015-12-08

    We report the thickness-dependent strain-relaxation behavior and the associated impacts upon the superconductivity in epitaxial La1.85Sr0.15CuO4 films grown on different substrates, which provide a range of strain. We have found that the critical thickness for the onset of superconductivity in La1.85Sr0.15CuO4 films is associated with the finite thickness effect and epitaxial strain. In particular, thin films with tensile strain greater than ~0.25% revealed no superconductivity. We attribute this phenomenon to the inherent formation of oxygen vacancies that can be minimized via strain relaxation.

  3. Effects of NiO on the conductivity of Ce0.85Sm0.15O1.925 and on electrochemical properties of the cathode/electrolyte interface

    NASA Astrophysics Data System (ADS)

    Wang, Haopeng; Liu, Xiaomei; Bi, Hailin; Yu, Shenglong; Han, Fei; Sun, Jialing; Zhu, Lili; Yu, Huamin; Pei, Li

    2016-07-01

    Ce0.85Sm0.15O1.925 (SDC) and Ce0.85Sm0.15O1.925-0.5 at.% NiO (SDCN) are investigated as electrolytes for solid oxide fuel cells (SOFCs). Impedance spectroscopy measurements reveal that the grain boundary resistance can be significantly reduced by adding 0.5 at.% NiO to SDC. Symmetric cells of the BaCo0.7Fe0.2Nb0.1O3-δ (BCFN) electrode on SDC and SDCN electrolytes are fabricated and the electrochemical properties of the electrode/electrolyte interface are investigated. The polarization resistance of the BCFN electrode on the SDCN electrolyte is much lower than that of the BCFN electrode on the SDC electrolyte, mainly because of the increase in the electrolyte conductivity and the decrease in the Si content at the electrode/electrolyte interface. NiO is able to restrict the diffusion of the siliceous impurity from the electrolyte to the electrode/electrolyte interface. Single cells based on SDC and SDCN electrolytes are fabricated using Ni0.9Cu0.1Ox-SDC as the anode and BCFN as the cathode. At 800 °C, the maximum power density of the SDCN-based cell is 0.745 W cm-2, which is much higher than that of the SDC-based cell.

  4. Dynamic in situ observations of electrical and structural changes in thin thermoelectric (Bi{sub 0.15}Sb{sub 0.85}){sub 2}Te{sub 3} films

    SciTech Connect

    Bertram, Katrin; Stordeur, Matthias; Heyroth, Frank; Leipner, Hartmut S.

    2009-09-15

    Thin films of (Bi{sub 0.15}Sb{sub 0.85}){sub 2}Te{sub 3} were prepared by dc magnetron sputter deposition on different substrates. It is well known that thermal treatment of as-deposited p-type (Bi{sub 0.15}Sb{sub 0.85}){sub 2}Te{sub 3} films leads to an enhancement of the power factor. Whereas up to now only the initial (as deposited) and the final (after annealing) film stages have been investigated, here, the dynamic changes of sputter-deposited film properties have been observed by in situ measurements. The enhancement of the power factor shows a significant dependence on thermal treatment. The best thermoelectric films have been prepared at a substrate temperature of 170 deg. C, with a power factor of 24.4 muW/(cm K{sup 2}). The changes in the Seebeck and Hall coefficients are caused by the enhancement in the Hall mobility after annealing. In situ x-ray diffractometry shows the generation of additional Te in dependence of the temperature. This is also confirmed by energy-dispersive x-ray microanalysis and the corresponding mapping in a scanning electron microscope. It is supposed that the locally well-defined Te enrichment is the reason for the improvement in the integral film transport properties.

  5. 21 cm Power Spectrum Upper Limits from PAPER-64

    NASA Astrophysics Data System (ADS)

    Shiraz Ali, Zaki; Parsons, Aaron; Pober, Jonathan; Team PAPER

    2016-01-01

    We present power spectrum results from the 64 antenna deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER-64). We find an upper limit of Δ2≤(22.4 mK)2 over the range 0.15cm power spectrum constraints to date. In addition, we use these results to place lower limits on the spin temperature at a redshift of 8.4. We find that the spin temperature is at least 10K for a neutral fraction between 15% and 80%. This further suggests that there was heating in the early universe through various sources such as x-ray binaries.

  6. Enhancement in optical and structural properties of Zn0.85Mg0.15O nanorods over thin films synthesized by hydrothermal chemical treatment

    NASA Astrophysics Data System (ADS)

    Murkute, P.; Sehara, N.; Ghadi, H.; Pandey, S. K.; Maity, S.; Chakrabarti, S.

    2016-02-01

    We are reporting an enhancement in optical properties by changing the structure of Zn0.85Mg0.15O thin films through formation of crystalline hexagonal nanorods. Zn0.85Mg0.15O thin films were deposited on Si (100) substrate using dielectric sputter followed by annealing in oxygen ambient at temperatures of 700, 800 and 900° C for 10 seconds to reduce oxygen vacancies defects. Deposited thin film annealed at 900 °C (sample A) measured highest peak intensity and it was subjected to controlled the hydrothermal bath conditioning for forming hexagonal nanorods. Four samples were dipped in 2 different solutions with variable molar ratio of zinc nitrate hexahydrate and hexamethylentetramine for 2 and 3 hours, respectively. Samples processed in solution 1 (1:1) ratio for 2 and 3 hours were named B and C and those in solution 2 (2:1) were D and E, respectively. Photoluminescence measurement at 18K demonstrates exciton near-band-edge (NBE) emission peak at 3.61eV from Zn0.85Mg0.15O sample A whereas other samples exhibited slight blue shift along with bimodal peaks. The other peak observed at lower energy 3.43eV corresponds to transitions due to presence of ZnO phase in Zn0.85Mg0.15O. All samples compared to sample A exhibited more than 10 times increment in peak intensities with sample B producing the highest (~ 20 times). Nanorods formation was confirmed using crosssectional SEM imaging. X-ray diffraction measurements revealed that all Zn0.85Mg0.15O samples had (002) preferred crystal orientation with peak position at 34.7°. All nanorods samples measured lower reflectance compared to sample A, indicating high absorption in nanorods due to high scattering of light at the nanorods surface.

  7. 77 FR 8877 - ICD-9-CM Coordination and Maintenance (C&M) Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-15

    ... HUMAN SERVICES Centers for Disease Control and Prevention ICD-9-CM Coordination and Maintenance (C&M... Standards Staff, announces the following meeting. Name: ICD-9-CM Coordination and Maintenance (C&M... attend the ICD- 9-CM C&M meeting on March 5, 2012, must submit their name and organization by February...

  8. Enhanced refrigeration capacity and magnetic entropy change in La0.55Ce0.15Sr0.3MnO3 manganite

    NASA Astrophysics Data System (ADS)

    Anwar, M. S.; Koo, Bon Heun

    2015-07-01

    The temperature dependent of the isothermal magnetic entropy change, Δ S M ( T), and the field dependence of the refrigeration capacity, RC, have been investigated in La0.7- x Ce x Sr0.30MnO3 ( x = 0.0 and 0.15). An enhanced RC and Δ S M ( T) were observed in La0.55Ce0.15Sr0.30MnO3. Under a magnetic field change of 2 T, the maximum improvement of 20% of Δ S M ( T) and 40% of RC, in comparison with La0.7Sr0.30MnO3, was observed. Moreover, Curie temperature of the La0.7Sr0.30MnO3 can tuned by adjusting the Ce concentration and makes this attractive for magnetic refrigeration at desired temperature. [Figure not available: see fulltext.

  9. Continuous wave and passively Q-switched Nd:Lu0.15Y0.85VO4 laser with 885 nm direct pumping

    NASA Astrophysics Data System (ADS)

    Li, Qi-nan; Zhao, Bin; Zhang, Tao; Li, Rei; Liu, Xiang-mei; Zheng, Ya-hui; Liu, Xiao-jun

    2015-05-01

    The 885 nm direct pumping directly into the 4F3/2 emitting level of Nd3+ is applied on an Nd:Lu0.15Y0.85VO4 crystal. The maximum output power of 2.8 W for continuous wave (CW) operation is obtained. For Q-switched operation, the maximum average output power is 1.2 W with pulse repetition of 23.69 kHz and pulse width of 35 ns at the pump power of 27.9 W. The high-quality fundamental transverse mode can be observed owing to the reduction of thermal effect for Nd:Lu0.15Y0.85VO4 crystal by 885 nm direct pumping.

  10. Chemical Reduction of Nd 1.85 Ce 0.15 CuO 4− δ Powders in Supercritical Sodium Ammonia Solutions

    DOE PAGESBeta

    Dias, Yasmin; Wang, Hui; Zhou, Haiqing; Lin, Feng; Lan, Yucheng

    2015-01-01

    Nd 1.85 Ce 0.15 CuO 4− δ powders are chemically reduced in supercritical sodium ammonia solutions from room temperature to 350°C. The crystallographic structure of the reduced powders is investigated from Rietveld refinement of X-ray powder diffraction. The atomic positions are maintained constant within experimental errors while temperature factors of all atoms increase significantly after the chemical treatments, especially of Nd/Ce atoms. The ammonothermally reduced Nd 1.85 Ce 0.15 CuO 4− δ powders show diamagnetic below 24 K which is contributed to the lower oxygen content and higher temperature factors of atoms in the treated compound.more » The ammonothermal method paves a new way to reduce oxides in supercritical solutions near room temperature.« less

  11. Doping of single crystals of the solid solution Bi/sub 2/Te/Sub 2. 85/Se/sub 0. 15/ with indium

    SciTech Connect

    Svechnikova, T.E.; Chizhevskaya, S.N.; Polikarpova, N.V.

    1987-12-01

    Perfect single crystals of the solid solution Bi/sub 2/Te/sub 2.85/Se/sub 0.15/ doped with In/sub 2/Te/sub 3/ (0.2 up to 5 mole % in the charge) were prepared by Czochralski's method with replenishment from the liquid phase. The indium content in the melts and in the single crystals was determined by the method of atomic-absorption spectroscopy. The effective distribution factor of indium in the solid solution Bi/sub 2/Te/sub 2.85/Se/sub 0.15/ equals /approx/ 0.5. Increasing the indium concentration in the solid solution decreases the electrical and thermal conductivity of the lattice.

  12. NOx emissions retrofit at Reliant Energy, W.A. Parish Generating Station, Unit 7: Achieving 0.15 lb/MBtu

    SciTech Connect

    Gessner, T.M.; Hoh, R.H.; Ray, B.; Dorazio, T.; Jennings, P.; Sikorski, K.

    1999-07-01

    The current Clean Air Act (CAA), Title 1 regulations require States to develop implementation plans (SIPs) which address NO{sub x} emissions as part of the ozone non-attainment requirements. The EPA has recommended NO{sub x} limits of 0.15 lb/MBtu for utility boilers. In this paper, Reliant Energy and ABB C-E Services, Inc. will discuss a project where 0.15 lb NO{sub x}/MBtu can be achieved with the TFS 2000{trademark} R firing system and highly reactive Powder River Basin (PRB) fuels. Reliant Energy will retrofit their W.A. Parish Unit 7 with this system in the first quarter of 1999. This is part of Reliant Energy's drive to lower NO{sub x} emissions and meet future air quality requirements at the W.Q. Parish station.

  13. Crystal structure and electrical properties of Ca {sub x}WO{sub 3} (0.01 {<=} x {<=} 0.15) prepared by hybrid microwave synthesis

    SciTech Connect

    Guo Juan . E-mail: guojuan@ssc.iphy.ac.cn; Dong Cheng; Yang Lihong; Fu Guangcai; Chen Hong

    2006-03-09

    Calcium tungsten bronzes Ca {sub x}WO{sub 3} (0.01 {<=} x {<=} 0.15) were synthesized by hybrid microwave method from mixtures of CaO, WO{sub 3} and tungsten powder. Single-phased samples can be obtained by microwave heating within 40 min. With the increase of calcium content, the crystal structure of Ca {sub x}WO{sub 3} transforms from orthorhombic (0.01 {<=} x {<=} 0.02) to tetragonal (0.03 {<=} x {<=} 0.11) and then to cubic (0.12 {<=} x {<=} 0.15). The average size of crystallites is in the range 1-5 {mu}m. All samples show semiconductor behaviour in their temperature dependence of resistivity. The electrical conduction mechanism changes from variable-range hopping to the thermally activated mechanism when x > 0.12.

  14. Ferroelectric domain structures in <001>-oriented K{sub 0.15}Na{sub 0.85}NbO{sub 3} lead-free single crystal

    SciTech Connect

    Chen, Yan; Wong, Chi-Man; Yau, Hei-Man; Dai, Jiyan; Deng, Hao; Luo, Haosu; Wang, Danyang; Yan, Zhibo; Chan, Helen L. W.

    2015-03-15

    In this work, ferroelectric domain structures of <001 >-oriented K{sub 0.15}Na{sub 0.85}NbO{sub 3} single crystal are characterized. Transmission electron microscopy (TEM) observation revealed high-density of laminate domain structures in the crystal and the lattices of the neighboring domains are found to be twisted in a small angle. Superlattice diffraction spots of 1/2 (eeo) and 1/2 (ooe) in electron diffraction patterns are observed in the crystal, revealing the a{sup +}a{sup +}c{sup −} tilting of oxygen octahedral in the perovskite structure. The piezoresponse of domains and in-situ poling responses of K{sub 0.15}Na{sub 0.85}NbO{sub 3} crystal are observed by piezoresponse force microscopy (PFM), and the results assure its good ferroelectric properties.

  15. Magnetic order in geometrically frustrated Gd2(Ti1-xZrx)2O7 (x=0.02 and 0.15) single crystals

    NASA Astrophysics Data System (ADS)

    Liao, Da-Qian; Lees, M. R.; Baker, D. W.; Paul, D. Mck.; Balakrishnan, G.

    2011-02-01

    Single crystals of Gd2(Ti1-xZrx)2O7 with x=0.02 and 0.15 have been used to investigate the effects of Zr doping on the properties of the geometrically frustrated antiferromagnet Gd2Ti2O7. Powder and single-crystal x-ray data, along with optical birefringence measurements, reveal that the x=0.02 sample retains the cubic Fd3¯m structure of pure Gd2Ti2O7, while the x=0.15 composition adopts a tetragonal I41/amd structure. Low-temperature magnetization and specific heat measurements show that for Gd2(Ti0.98Zr0.02)2O7 there are two magnetic transitions at TN1=1.02 K and TN2=0.70 K, but for Gd2(Ti0.85Zr0.15)2O7 a single transition is observed at TN=1.02 K. Changes in the specific heat with a magnetic field applied along the [110] and the [111] directions are used to construct the H-T phase diagrams for both samples.

  16. Thickness dependent optical properties of PEMA and (PEMA)0.85/(ZnO)0.15 nanocomposite films deposited by spray pyrolysis technique on ITO substrate

    NASA Astrophysics Data System (ADS)

    Thakur, Anjna; Thakur, Priya; Yadav, Kamlesh

    2016-05-01

    In this paper, poly (ethyl methacrylate) (PEMA) and (PEMA)0.85/(ZnO)0.15 nanocomposite films for 2, 3, 4 and 5 minutes have been deposited by spray pyrolysis technique on indium tin oxide (ITO) coated substrate. The effect of thickness of the film on the morphological and optical properties of PEMA and (PEMA)0.85/(ZnO)0.15 nanocomposite films are studied. The morphological and optical properties of pure PEMA and (PEMA)0.85/(ZnO)0.15 nanocomposite films are compared. The field emission scanning electron microscopy (FESEM) shows that as the thickness of film increases, uniformity of films increases. It is found from UV-Visible spectra that the energy band gap decreases with increasing the deposition time and refractive index increases with increasing the thickness of the film. The band gap of the nanocomposites is found less than the pure polymer film and opposite trend is observed for refractive index. The optical absorption of PEMA/ZnO nanocomposite films is higher than pure PEMA film. The thickness of the nanocomposite film plays a significant role in the tunability of the optical properties.

  17. Giant low-field magnetocaloric effect in single-crystalline EuTi0.85Nb0.15O3

    NASA Astrophysics Data System (ADS)

    Roy, S.; Khan, N.; Mandal, P.

    2016-02-01

    The magnetocaloric effect in ferromagnetic single crystal EuTi0.85Nb0.15O3 has been investigated using magnetization and heat capacity measurements. EuTi0.85Nb0.15O3 undergoes a continuous ferromagnetic phase transition at TC = 9.5 K due to the long range ordering of magnetic moments of Eu2+ (4f7). With the application of magnetic field, the spin entropy is strongly suppressed and a giant magnetic entropy change is observed near TC. The values of entropy change ΔSm and adiabatic temperature change ΔTad are as high as 51.3 J kg-1 K-1 and 22 K, respectively, for a field change of 0-9 T. The corresponding magnetic heating/cooling capacity is 700 J kg-1. This compound also shows large magnetocaloric effect even at low magnetic fields. In particular, the values of ΔSm reach 14.7 and 23.8 J kg-1 K-1 for field changes of 0-1 T and 0-2 T, respectively. The low-field giant magnetocaloric effect, together with the absence of thermal and field hysteresis makes EuTi0.85Nb0.15O3 a very promising candidate for low temperature magnetic refrigeration.

  18. Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La1-xBaxF3-x (x < 0.15).

    PubMed

    Chable, Johann; Dieudonné, Belto; Body, Monique; Legein, Christophe; Crosnier-Lopez, Marie-Pierre; Galven, Cyrille; Mauvy, Fabrice; Durand, Etienne; Fourcade, Sébastien; Sheptyakov, Denis; Leblanc, Marc; Maisonneuve, Vincent; Demourgues, Alain

    2015-12-01

    Pure tysonite La1-xBaxF3-x solid solutions for x < 0.15 were prepared by solid state synthesis in a platinum tube under an azote atmosphere with subsequent quenching for 0.07 ≤x < 0.15. The solid solutions were studied by X-ray, electron and neutron diffractions and by (19)F NMR and impedance spectroscopy. The evolution of the cell parameters obeying Vegard's rule was determined for 0 < x≤ 0.15 and atomic position parameters were accurately refined for x = 0.03, 0.07 and 0.10. The chemical pressure induced by large Ba(2+) cations leads to an increase of the unit cell parameters. Fluorine environment and mobilities are discussed on the basis of the results of neutron diffraction and (19)F solid state NMR. The F1 subnetwork is lacunar; fluorine exchange occurs according to the order: F1-F1 and F1-F2,3. 2D EXSY NMR spectra of La0.97Ba0.03F2.97 reveal, for the first time, a chemical exchange between F2 and F3 sites that requires two successive jumps. The ionic conductivity was evaluated from sintered pellets and different shaping methods were compared. The only structural features which could explain the conductivity maximum are a crossover together with a smaller dispersion of F1-F1,2,3 distances at x = 0.05-0.07. PMID:26246328

  19. Preferential orientation and thermoelectric properties of n-type Bi2Te2.85Se0.15 alloys by mechanical alloying and equal channel angular extrusion

    NASA Astrophysics Data System (ADS)

    Fan, X. A.; Yang, J. Y.; Zhu, W.; Bao, S. Q.; Duan, X. K.; Xiao, C. J.; Li, K.

    2007-09-01

    Starting from elemental bismuth, tellurium and selenium powders, n-type Bi2Te2.85Se0.15 solid solution with a fine microstructure was prepared by mechanical alloying and equal channel angular extrusion (ECAE) in the present work. The effect of extrusion temperature on the microstructure and thermoelectric properties of the as-ECAEed samples was investigated. A preferentially oriented microstructure with the basal planes (0 0 l) in the parallel direction to extrusion was formed, and the orientation factors F of the (0 0 l) planes of the 703 K and 753 K ECAEed Bi2Te2.85Se0.15 alloys were 0.26 and 0.28, respectively. The electrical resistivity and the Seebeck coefficient decreased, and the thermal conductivity increased with increasing extrusion temperature. The electrical and thermal transmission performances were strongly affected by the preferentially oriented microstructure and the preferential orientation improved the thermoelectric properties of the ECAEed Bi2Te2.85Se0.15 alloys in the parallel direction to extrusion. The maximum dimensionless figure of merit was obtained when extruded at 753 K at a testing temperature of 343 K, ZT = 0.66.

  20. Deformation Behavior and Microstructure Evolution of the Cu-2Ni-0.5Si-0.15Ag Alloy During Hot Compression

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Volinsky, Alex A.; Xu, Qian-Qian; Chai, Zhe; Tian, Baohong; Liu, Ping; Tran, Hai T.

    2015-12-01

    Hot deformation behavior of the Cu-2Ni-0.5Si-0.15Ag alloy was investigated by hot compression tests using the Gleeble-1500D thermo-simulator in the 873 K to 1073 K (600 °C to 800 °C) temperatures range with the 0.01 to 5 s-1 strain rate. The flow stress strongly depends on the deformation parameters, including temperature and strain rate. The flow stress decreases with the deformation temperature and increases with the strain rate. The constitutive relationship between the peak stress, the strain rate, and the deformation temperature can be described by the Zener-Hollomon Z parameter in the hyperbolic sine function with the hot deformation activation energy of 316 kJ/mol. The dynamic recrystallization (DRX) is one of the important softening mechanisms of the Cu-2Ni-0.5Si-0.15Ag alloy during hot deformation. The DRX behavior of the Cu-2Ni-0.5Si-0.15Ag alloy is strongly affected by the Z parameter. Lower Z parameter leads to more adequate DRX proceeding.

  1. Energy Transfer in Rare Earth Ion Clusters and Fluorescence from Rare Earth Doped LANTHANUM(1.85)STRONTIUM(0.15)COPPER -OXYGEN(4) Superconductors.

    NASA Astrophysics Data System (ADS)

    Tissue, Brian Max

    1988-12-01

    Laser spectroscopy of rare earth ions in solids was used to study mechanisms of non-resonant energy transfer within rare earth clusters, and to detect insulating, impurity phases in rare earth doped La_{1.85 }Sr_{0.15}CuO _4 superconductors. The mechanisms of phonon-assisted, non-resonant energy transfer were studied in well-defined dimer sites in Er^{3+ }:SrF_2 and Pr ^{3+}:CaF_2. Application of a magnetic field to Er^{3+} :SrF_2 greatly increased the energy transfer rate. The magnetic field dependence in Er^{3+}:SrF _2 indicates that the mechanism of non-resonant energy transfer is a two-phonon, resonant process (Orbach process). Application of a magnetic field to Pr ^{3+}:CaF_2 had no effect on the energy transfer rate because no significant Zeeman splittings occurred. The temperature dependence of the energy transfer rate in Pr^{3+ }:CaF_2 showed the mechanism to be a one-phonon-assisted process at low temperatures and predominantly an Orbach process above 10 K. In the second part of this thesis, laser spectroscopy of a Eu ^{3+} probe ion is developed to detect impurity phases in La_{1.85 }Sr_{0.15}CuO _4 superconductors. Two impurity phases were found in polycrystalline La_ {1.85}Sr_{0.15} CuO_4: unreacted La _2O_3 starting material, and a La-silicate phase, which formed from contamination during sintering. The spectroscopic technique was found to be more than 100 times more sensitive than powder x -ray diffraction to detect minor impurity phases. In preparing the superconductors, several studies were made on the effect of Pr^{3+}, Eu ^{3+}, Bi^{3+ }, and fluorine dopants on the superconducting properties of La_{1.85}Sr _{0.15}CuO_4 and La_2Cuo_4 . Pr^{3+}, Eu ^{3+}, Bi^ {3+}, and F_2 doping all decreased the superconductivity in La_ {1.85}Sr^{0.15} CuO_4. Treating semi-conducting La_2CuO_4 in F_2 gas converted it to a superconductor with an onset T_{rm c} of 30-35 K.

  2. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ∼1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (∼0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  3. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  4. Optimization of the electrochemical performance of a Ni/Ce0.9Gd0.1O2-δ-impregnated La0.57Sr0.15TiO3 anode in hydrogen

    NASA Astrophysics Data System (ADS)

    Xia, Tian; Brüll, Annelise; Grimaud, Alexis; Fourcade, Sébastien; Mauvy, Fabrice; Zhao, Hui; Grenier, Jean-Claude; Bassat, Jean-Marc

    2014-09-01

    A-site deficient perovskite La0.57Sr0.15TiO3 (LSTO) materials are synthesized by a modified polyacrylamide gel route. X-ray diffraction pattern of LSTO indicates an orthorhombic structure. The thermal expansion coefficient of LSTO is 10.0 × 10-6 K-1 at 600 °C in 5%H2/Ar. LSTO shows an electrical conductivity of 2 S cm-1 at 600 °C in 3%H2O/H2. A new composite material, containing the porous LSTO backbone impregnated with small amounts of Ce0.9Gd0.1O2-δ (CGO) (3.4-8.3 wt.%) and Ni/Cu (2.0-6.3 wt.%), is investigated as an alternative anode for solid oxide fuel cells (SOFCs). Because of the substantial electro-catalytic activity of the fine and well-dispersed Ni particles on the surface of the ceramic framework, the polarization resistance of 6.3%Ni-8.3%CGO-LSTO anode reaches 0.73 Ω cm2 at 800 °C in 3%H2O/H2. In order to further improve the anodic performance, corn starch and carbon black are used as pore-formers to optimize the microstructure of anodes.

  5. Gas-Phase Oxidation of Cm+ and Cm2+ -- Thermodynamics of neutral and ionized CmO

    SciTech Connect

    Gibson, John K; Haire, Richard G.; Santos, Marta; Pires de Matos, Antonio; Marcalo, Joaquim

    2008-12-08

    Fourier transform ion cyclotron resonance mass spectrometry was employed to study the products and kinetics of gas-phase reactions of Cm+ and Cm2+; parallel studies were carried out with La+/2+, Gd+/2+ and Lu+/2+. Reactions with oxygen-donor molecules provided estimates for the bond dissociation energies, D[M+-O](M = Cm, Gd, Lu). The first ionization energy, IE[CmO], was obtained from the reactivity of CmO+ with dienes, and the second ionization energies, IE[MO+](M = Cm, La, Gd, Lu), from the rates of electron-transfer reactions from neutrals to the MO2+ ions. The following thermodynamic quantities for curium oxide molecules were obtained: IE[CmO]= 6.4+-0.2 eV; IE[CmO+]= 15.8+-0.4 eV; D[Cm-O]= 710+-45 kJ mol-1; D[Cm+-O]= 670+-40 kJ mol-1; and D[Cm2+-O]= 342+-55 kJ mol-1. Estimates for the M2+-O bond energies for M = Cm, La, Gd and Lu are all intermediate between D[N2-O]and D[OC-O]--i.e., 167 kJ mol-1< D[M2+-O]< 532 kJ mol-1 -- such that the four MO2+ ions fulfill the thermodynamic requirement for catalytic O-atom transport from N2O to CO. It was demonstrated that the kinetics are also favorable and that the CmO2+, LaO2+, GdO2+ and LuO2+ dipositive ions each catalyze the gas-phase oxidation of CO to CO2 by N2O. The CmO2+ ion appeared during the reaction of Cm+ with O2 when the intermediate, CmO+, was not collisionally cooled -- although its formation is kinetically and/or thermodynamically unfavorable, CmO2+ is a stable species.

  6. Multiferroic properties of nanocrystalline BiFe1-xNixO3 (x=0.0-0.15) perovskite ceramics

    NASA Astrophysics Data System (ADS)

    Chaudhari, Yogesh; Mahajan, Chandrashekhar M.; Singh, Amrita; Jagtap, Prashant; Chatterjee, Ratnamala; Bendre, Subhash

    2015-12-01

    Ni doped BiFeO3 (x=0, 0.05, 0.1 and 0.15) nanocrystalline ceramics were synthesized by the solution combustion method (SCM) to obtain optimal multiferroic properties. The effect of Ni doping on structural, morphological, ferroelectric, magnetic and dielectric properties of BiFeO3 was studied. The structural investigations by using X-ray diffraction (XRD) pattern confirmed that BiFe1-xNixO3 ceramics have rhombhohedral perovskite structure. The ferroelectric hysteresis measurements for BiFe1-xNixO3 (x=0, 0.05, 0.1, 0.15) compound at room temperature found to exhibit unsaturated behavior and presents partial reversal of polarization. The magnetic measurements demonstrated an enhancement of ferromagnetic property due to Ni doping in BiFeO3 when compared with undoped BiFeO3. The variation of dielectric constant with temperature in BiFe0.9Ni0.1O3 and BiFe0.85Ni0.15O3 samples evidenced an apparent dielectric anomaly around 350 °C and 300 °C which corresponds to antiferromagnetic to paramagnetic phase transition of (TN) of BiFeO3. The dependence of room temperature dielectric properties on frequency signifies that both dielectric constant (ε) and dielectric loss (tan δ) are the strong function of frequency. The results show that solution combustion method leads to synthesis of an excellent and reproducible BiFe1-xNixO3 multiferroic ceramics.

  7. Application of antiferromagnetic-Fermi-liquid theory to NMR experiments in La1.85Sr0.15CuO4

    NASA Astrophysics Data System (ADS)

    Monien, H.; Monthoux, P.; Pines, D.

    1991-01-01

    NMR experiments on La1.85Sr0.15CuO4 by Kitaoka et al. and Imai et al. are analyzed using the phenomenological antiferromagnetic (AF) Fermi liquid theory of Millis, Monien, and Pines, and the results are compared with those previously obtained for YBa2Cu3O7 and YBa2Cu3O6.63. A one-component model, with hyperfine couplings that are unchanged from those found previously for YBa2Cu3O7 and YBa2Cu3O6.63, and parameters obtained from experiment, provide a quantitative fit to the data. At all temperatures the antiferromagnetic correlations found in La1.85Sr0.15CuO4 are stronger than those found for the Y-Ba-Cu-O samples with the result that the characteristic energy for the antiferromagnetic paramagnons that describe the AF spin dynamics is quite low (0.15CuO4, YBa2Cu3O7, and YBa2Cu3O6.63, and find that it displays a linear temperature dependence for all three materials. Our results support the proposal that the properties of a nearly antiferromagnetic Fermi liquid are genuinely novel, and suggest that both the spin and charge aspects of the normal-state properties of the cuprate oxide superconductors can be quantitatively explained in terms of quasiparticles coupled to antiferromagnetic paramagnons whose characteristic energy scale is

  8. Sintering of BaCe(0.85)Y(0.15)O3-(Beta) With/Without SrTiO Dopant

    NASA Technical Reports Server (NTRS)

    Dynys, Fred; Sayir, Ali; Heimann, Paula J.

    2004-01-01

    The sintering behavior of BaCe(0.85)Y(0.15)O3-(Beta) doped with SrTiO is described. Complete reaction and crystallization of perovskite phase by solid state was achieved by calcining at 1200 degrees C for 24 hours.Smaples were sintered at 1450 degrees C, 1550 degrees C, and 1650 degrees C. SrTiOsub3 enhanced sintering, while optimal dopant level was different for powders synthesized by solid state and co-precipitation. Both powders exhibit similar grain growth behavior.

  9. Wind-tunnel free-flight investigation of a 0.15-scale model of the F-106B airplane with vortex flaps

    NASA Technical Reports Server (NTRS)

    Yip, Long P.

    1987-01-01

    An investigation to determine the effects of vortex flaps on the flight dynamic characteristics of the F-106B in the area of low-speed, high-angle-of-attack flight was undertaken on a 0.15-scale model of the airplane in the Langley 30- by 60-Foot Tunnel. Static force tests, dynamic forced-oscillation tests, as well as free-flight tests were conducted to obtain a data base on the flight characteristics of the F-106B airplane with vortex flaps. Vortex flap configurations tested included a full-span gothic flap, a full-span constant-chord flap, and a part-span gothic flap.

  10. Critical state and low-field electrodynamics in LaO{sub 0.85}F{sub 0.15}FeAs superconductor polycrystals

    SciTech Connect

    Gerashchenko, O. V.; Kholmetskii, A. L.; Mashlan, M.; Yarman, T.; Aldushchenkov, A. V.; Okunev, I. S.; Lomonosov, V. A.; Makhnach, L. V.

    2015-06-15

    The penetration of a weak magnetic field into LaO{sub 0.85}F{sub 0.15}FeAs polycrystalline superconductors is investigated using two mutually complementing techniques: measurement of the higher harmonics of nonlinear magnetization and the current-voltage characteristics. The dependences of the critical current density and resistivity on the temperature and magnetic field strength are determined. The results confirm the theory of the critical state in the low-field electrodynamics of a Josephson medium. The universality of this theoretical concept is demonstrated for a new class of ceramic superconductors.

  11. Oxygen depth profiling with subnanometre depth resolution

    NASA Astrophysics Data System (ADS)

    Kosmata, Marcel; Munnik, Frans; Hanf, Daniel; Grötzschel, Rainer; Crocoll, Sonja; Möller, Wolfhard

    2014-10-01

    A High-depth Resolution Elastic Recoil Detection (HR-ERD) set-up using a magnetic spectrometer has been taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf for the first time. This instrument allows the investigation of light elements in ultra-thin layers and their interfaces with a depth resolution of less than 1 nm near the surface. As the depth resolution is highly influenced by the experimental measurement parameters, sophisticated optimisation procedures have been implemented. Effects of surface roughness and sample damage caused by high fluences need to be quantified for each kind of material. Also corrections are essential for non-equilibrium charge state distributions that exist very close to the surface. Using the example of a high-k multilayer SiO2/Si3N4Ox/SiO2/Si it is demonstrated that oxygen in ultra-thin films of a few nanometres thickness can be investigated by HR-ERD.

  12. Effects of soil depth on the dynamics of selected soil properties among the highlands resources of Northeast Wollega, Ethiopia: are these sign of degradation?

    NASA Astrophysics Data System (ADS)

    Adugna, A.; Abegaz, A.

    2015-07-01

    This study was conducted with an aim to analyze the spatial variability of soil properties with depth under four prominent land use patterns viz., forestland, grazing land, cultivated land and bush land of Northeast Wollega. Soil samples were collected from the land uses at two depths (0-15 and 15-30 cm) in replicates and totally 40 composite soil samples were collected. Statistical analysis revealed significant variation in soil properties with along the selected land uses. Topsoil layer had significantly greater OM, TN, AP, sand, silt, Mg2+, K+ and Mg2+ concentrations than the subsoil layers. However, clay under all land uses and CEC under bush land and grazing land revealed reverse trends. Organic matter and CEC have stronger correlations with most of soil properties in the topsoil than in the subsoil while clay has no significant correlation with selected soil properties except with sand fraction in the sampled depths. Hence, the correlation among the selected soil properties also varies with soil depth. In general, the spatial variability of soil properties indicates that they were strongly affected by external factors (agricultural treatments and soil management practices) and internal factors (soil type and depth).

  13. Soil Warming and Rhizosphere Effects on Root Litter Decomposition at Two Depths in a Mediterranean Grassland Ecosystem

    NASA Astrophysics Data System (ADS)

    Castanha, C.; Zhu, B.; Hicks Pries, C.; Torn, M. S.

    2015-12-01

    Accurate understanding of soil processes is critical for predicting climate-ecosystem feedbacks. We investigated the effects of soil warming and plant rhizosphere on decomposition of 13C-labeled roots buried at two soil depths at the field lysimeter facilities at Hopland Research and Extension Center, CA. The lysimeters contain soil columns 38-cm in diameter and 48-cm deep (0-15 cm A-horizon and 15-48 cm B-horizon, Laughlin soil) sown with an annual grassland mix. The experimental design includes three treatments: heated, ambient, and unplanted. In February 2014 we added 13C-labeled Avena fatua roots to either 8-12 cm or 38-42 cm. We measured loss of 13C in CO2 from the soil surface and in leachate as dissolved organic carbon (DOC) over two growing seasons. At the end of each growing season we recovered the 13C remaining in the soil. In addition, we monitored plant productivity and soil temperature and moisture. The rates of both soil respiration and DOC losses were greatest in heated and least in unplanted plots, although respiration losses far outweighed leachate losses. Treatment affected timing of decomposition; added root litter was respired earlier in the ambient plots and later in the unplanted plots in both years. The litter addition stimulated native soil respiration in year 1 heated plots. The depth of the litter addition did not have an effect on soil respiration. However, after the first growing season, less added root litter remained in the A than in the B horizon (both in the visible root fraction and in the 2mm soil fraction), indicating lower overall decomposition rates at depth. These results, including 13C recovery following the 2nd growing season and soil microclimate variables, will be used to develop a mechanistic understanding of the impacts of soil warming, the rhizosphere, and soil depth on root decomposition and soil organic matter dynamics, and should improve our predictions of the feedbacks between climate change and carbon cycling

  14. Disorder induced superconductor-insulator transition in epitaxial La1.85Sr0.15CuO4 thin films

    NASA Astrophysics Data System (ADS)

    Jang, Han-Byul; Yang, Chan-Ho

    La2-xSrxCuO4is a well-known superconducting system showing various electronic properties as a function of Sr content. Especially, epitaxial thin layers of the compound show enormous increase of superconducting critical temperature (Tc) by a compressive strain. It has been reported that Tc can be controlled by misfit strain, thickness, and oxygen annealing. In this study, we report structural and transport properties of high quality epitaxial La1.85Sr0.15CuO4thin films. According to x-ray diffraction study, c-axis lattice parameter shows no significant change for various film thicknesses and the in-plane lattice parameters of the films are coherently matched with that of substrate. Electronic transport measurements show a clear superconductor-to-insulator transition (SIT), accompanying variation of Tc depending on film thickness. These results are analyzed by using the McMillan equation to find the relation between the Tc and a disorder correlating with film thickness. We have found the disorder exhibits an explicit power-law behavior with respect to film thickness in our La1.85Sr0.15CuO4 thin films.

  15. Raman effect, structural and dielectric properties of sol-gel synthesized polycrystalline GaFe1-xZrxO3 (0≤x≤0.15)

    NASA Astrophysics Data System (ADS)

    Kumar, Rajeev; Mall, Ashish Kumar; Gupta, Rajeev

    2016-05-01

    Polycrystalline ceramic samples of Zirconium (Zr)-doped GaFeO3 (GaFe1-xZrxO3) were studied using powder X-ray diffraction, complex impedance spectroscopy and Raman spectroscopic measurements to understand the effect of Zr doping on the structural and dielectric properties. The samples with varying Zr content were prepared by Sol-Gel method. X-ray data analysis confirmed the formation of single phase material without formation of any secondary phases and all are crystallized in Pc21n orthorhombic symmetry. Rietveld refinement of the X-ray data suggested an increase in the lattice constants due to size effect and decreases on x = 0.15 due to the effect of change in interplanner spacing. Impedance studies on the samples showed that the dielectric constant increases while loss tangent decrease as the Zr content increases. Raman scattering on GaFe1-xZrxO3 (x = 0, 0.05, 0.10, & 0.15) used to understand the composition dependence on phonon modes at room temperature. On Zr doping, Raman modes frequencies shifts to lower energies consistent with the X-ray data.

  16. Effect of granularity and annealing conditions on the magneto-resistance of the electron doped superconductor Nd1.85Ce0.15CuO4

    NASA Astrophysics Data System (ADS)

    Raveendran, N. Radhikesh; Amaladass, E. P.; Janaki, J.; Mani, Awadhesh

    2016-05-01

    A single phase polycrystalline sample of Nd1.85Ce0.15CuO4 has been synthesized and well characterized. Detailed studies on electrical resistivity behavior of this system as a function of temperature and magnetic field reveal interesting features attributable to the granularity effects. These features have been qualitatively understood based on the interplay of Josephson junction coupling and quasi particle tunneling which dictates the evolution of the observed temperature and field dependent resistivity behavior of Nd1.85Ce0.15CuO4 system. The studies also reveal significant changes with respect to annealing conditions, indicating that such compounds are very sensitive to annealing conditions. It has been observed that prolonged annealing in Argon atmosphere leads to a decrease in normal state resistivity. This is associated with a decrease in the S-I-S type Josephson tunnel junctions perhaps due to improved inter-granular coupling, nevertheless they could not be completely eliminated.

  17. Electrical study and dielectric relaxation behavior in nanocrystalline Ce0.85Gd0.15O2- δ material at intermediate temperatures

    NASA Astrophysics Data System (ADS)

    Kumar Baral, Ashok; Sankaranarayanan, V.

    2010-02-01

    The nanocrystalline material of 15 mol% Gd-doped ceria (Ce0.85Gd0.15O2- δ ) was prepared by citrate auto ignition method. The electrical study and dielectric relaxation technique were applied to investigate the ionic transport process in this nanocrystalline material with an average grain size of 13 nm and the dynamic relaxation parameters are deduced in the temperature range of 300-600°C. The ionic transference number in the material is found to be 0.85 at 500°C at ambient conditions. The oxygen ionic conduction in the nanocrystalline Ce0.85Gd0.15O2- δ material follows the hopping mechanism. The grain boundary relaxation is found to be associated with migration of charge carriers. The frequency spectra of modulus M″ exhibited a dielectric relaxation peak corresponding to defect associates (Gd-Vo^{_{_{{blacksquare blacksquare}}}})^{_{_{{blacksquare}}}}. The material exhibits very low values of migration energy and association energy of the oxygen vacancies in the long-range motion, i.e., 0.84 and 0.07 eV, respectively.

  18. Fully reversible hydrogen absorption and desorption reactions with Sc(Al{sub 1-x}Mg{sub x}), x=0.0, 0.15, 0.20

    SciTech Connect

    Sahlberg, Martin; Zlotea, Claudia; Latroche, Michel; Andersson, Yvonne

    2011-01-15

    The hydrogen storage properties of Sc(Al{sub 1-x}Mg{sub x}), x=0.0, 0.15, 0.20, have been studied by X-ray powder diffraction, thermal desorption spectroscopy, pressure-composition-isotherms and scanning electron microscopy techniques. Hydrogen is absorbed from the gas phase at 70 kPa and 400 {sup o}C under the formation of ScH{sub 2} and aluminium with magnesium in solid solution. The reaction is fully reversible in vacuum at 500 {sup o}C and shows the hydrogenation-disproportionation-desorption-recombination (HDDR) behaviour. The activation energy of desorption was determined by the Kissinger method to 185 kJ/mol. The material is stable up to at least six absorption-desorption cycles and there is no change in particle size during cycling. -- Graphical abstract: XRD pattern of Sc(Al{sub 1-x}Mg{sub x}). From the top: x=0, 0.15, 0.20. The hydrogen absorption properties were studied by thermal desorption spectroscopy, pressure-composition-isotherms and scanning electron microscopy techniques. Display Omitted

  19. Alpha self-irradiation effect on the local structure of the U0.85Am0.15O2±x solid solution

    NASA Astrophysics Data System (ADS)

    Prieur, D.; Martin, P. M.; Lebreton, F.; Delahaye, T.; Jankowiak, A.; Laval, J.-P.; Scheinost, A. C.; Dehaudt, P.; Blanchart, P.

    2012-10-01

    Uranium-americium mixed oxides are promising fuels for achieving an efficient Am recycling. Previous studies on U0.85Am0.15O2±x materials showed that the high α activity of 241Am induces pellet swelling which is a major issue for cladding materials design. In this context, X-ray Diffraction and X-ray Absorption Spectroscopy measurements were used to study self-irradiation effects on U0.85Am0.15O2±x local structure and to correlate these results with those obtained at the macroscopic scale. For a cumulative α decay dose equal to 0.28 dpa, it was shown that non-defective fluorite solid solutions were achieved and therefore, that the fluorite structure is stable for the studied doses. In addition, both interatomic distance and lattice parameter expansions were observed, which only partially explains the macroscopic swelling. As expected, an increase of the structural disorder with self-irradiation was also observed.

  20. Enhanced electrochemical performance and storage property of LiNi0.815Co0.15Al0.035O2 via Al gradient doping

    NASA Astrophysics Data System (ADS)

    Duan, Jianguo; Hu, Guorong; Cao, Yanbing; Tan, Chaopu; Wu, Ceng; Du, Ke; Peng, Zhongdong

    2016-09-01

    LiNi1-x-yCoxAlyO2 is a commonly used Ni-rich cathode material because of its relatively low cost, excellent rate capability and high gravimetric energy density. Surface modification is an efficient way to overcome the shortcomings of Ni-rich cathodes such as poor cycling stability and poor thermal stability. A high-powered concentration-gradient cathode material with an average composition of LiNi0.815Co0.15Al0.035O2 (LGNCAO) has been successfully synthesized by using spherical concentration-gradient Ni0.815Co0.15Al0.035(OH)2 (GNCA)as the starting material. An efficient design of the Al3+ precipitation method is developed, which enables obtaining spherical GNCA with ∼10 μm particle size and high tap density. In LGNCAO, the nickel and cobalt concentration decreases gradually whereas the aluminum concentration increases from the centre to the outer layer of each particle. Electrochemical performance and storage properties of LGNCAO have been investigated comparatively. The LGNCAO displays better electrochemical performance and improved storage stability than LNCAO.

  1. Zinc substitution effects on the superconducting properties of Nd sub 1. 85 Ce sub 0. 15 CuO sub 4-. delta

    SciTech Connect

    Garcia-Vazquez, V.; Mazumdar, S.; Falco, C.M.; Barlingay, C.; Risbud, S.H.

    1990-01-01

    With the discovery of the electron superconductors, a new dimension was added to research in the field of high-temperature superconductivity. Studies of these materials should help elucidate the mechanism responsible for high-temperature superconductivity, as well as improve strategies for finding new superconductors. In this paper, we discuss the superconducting structural properties of Nd{sub 1.85}Ce{sub 0.15}(Cu{sub 1-y}Zn{sub y})O{sub 4} as a function of the Zn concentration y. Detailed comparisons with previous results of similar substitution studies in the single-CuO{sub 2}-layer hole superconductor La{sub 1.85}Sr{sub 0.15}CuO{sub 4} also are made. We have found that the non-magnetic element Zn has a detrimental effect on the T{prime}-phase electron superconductor, and that this effect is as strong as in the T-phase hole superconductor. Theoretical implications and the question of electron-hole symmetry are also discussed.

  2. Zinc substitution effects on the superconducting properties of Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4-{delta}}

    SciTech Connect

    Garcia-Vazquez, V.; Mazumdar, S.; Falco, C.M.; Barlingay, C.; Risbud, S.H.

    1990-12-31

    With the discovery of the electron superconductors, a new dimension was added to research in the field of high-temperature superconductivity. Studies of these materials should help elucidate the mechanism responsible for high-temperature superconductivity, as well as improve strategies for finding new superconductors. In this paper, we discuss the superconducting structural properties of Nd{sub 1.85}Ce{sub 0.15}(Cu{sub 1-y}Zn{sub y})O{sub 4} as a function of the Zn concentration y. Detailed comparisons with previous results of similar substitution studies in the single-CuO{sub 2}-layer hole superconductor La{sub 1.85}Sr{sub 0.15}CuO{sub 4} also are made. We have found that the non-magnetic element Zn has a detrimental effect on the T{prime}-phase electron superconductor, and that this effect is as strong as in the T-phase hole superconductor. Theoretical implications and the question of electron-hole symmetry are also discussed.

  3. Stereoscopic depth constancy.

    PubMed

    Guan, Phillip; Banks, Martin S

    2016-06-19

    Depth constancy is the ability to perceive a fixed depth interval in the world as constant despite changes in viewing distance and the spatial scale of depth variation. It is well known that the spatial frequency of depth variation has a large effect on threshold. In the first experiment, we determined that the visual system compensates for this differential sensitivity when the change in disparity is suprathreshold, thereby attaining constancy similar to contrast constancy in the luminance domain. In a second experiment, we examined the ability to perceive constant depth when the spatial frequency and viewing distance both changed. To attain constancy in this situation, the visual system has to estimate distance. We investigated this ability when vergence, accommodation and vertical disparity are all presented accurately and therefore provided veridical information about viewing distance. We found that constancy is nearly complete across changes in viewing distance. Depth constancy is most complete when the scale of the depth relief is constant in the world rather than when it is constant in angular units at the retina. These results bear on the efficacy of algorithms for creating stereo content.This article is part of the themed issue 'Vision in our three-dimensional world'. PMID:27269596

  4. Stereoscopic depth constancy

    PubMed Central

    Guan, Phillip

    2016-01-01

    Depth constancy is the ability to perceive a fixed depth interval in the world as constant despite changes in viewing distance and the spatial scale of depth variation. It is well known that the spatial frequency of depth variation has a large effect on threshold. In the first experiment, we determined that the visual system compensates for this differential sensitivity when the change in disparity is suprathreshold, thereby attaining constancy similar to contrast constancy in the luminance domain. In a second experiment, we examined the ability to perceive constant depth when the spatial frequency and viewing distance both changed. To attain constancy in this situation, the visual system has to estimate distance. We investigated this ability when vergence, accommodation and vertical disparity are all presented accurately and therefore provided veridical information about viewing distance. We found that constancy is nearly complete across changes in viewing distance. Depth constancy is most complete when the scale of the depth relief is constant in the world rather than when it is constant in angular units at the retina. These results bear on the efficacy of algorithms for creating stereo content. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269596

  5. Polarization lidar for shallow water depth measurement.

    PubMed

    Mitchell, Steven; Thayer, Jeffrey P; Hayman, Matthew

    2010-12-20

    A bathymetric, polarization lidar system transmitting at 532 nm and using a single photomultiplier tube is employed for applications of shallow water depth measurement. The technique exploits polarization attributes of the probed water body to isolate surface and floor returns, enabling constant fraction detection schemes to determine depth. The minimum resolvable water depth is no longer dictated by the system's laser or detector pulse width and can achieve better than 1 order of magnitude improvement over current water depth determination techniques. In laboratory tests, an Nd:YAG microchip laser coupled with polarization optics, a photomultiplier tube, a constant fraction discriminator, and a time-to-digital converter are used to target various water depths with an ice floor to simulate a glacial meltpond. Measurement of 1 cm water depths with an uncertainty of ±3 mm are demonstrated using the technique. This novel approach enables new approaches to designing laser bathymetry systems for shallow depth determination from remote platforms while not compromising deep water depth measurement. PMID:21173834

  6. Intensity Mapping During Reionization: 21 cm and Cross-correlations

    NASA Astrophysics Data System (ADS)

    Aguirre, James E.; HERA Collaboration

    2016-01-01

    The first generation of 21 cm epoch of reionization (EoR) experiments are now reaching the sensitivities necessary for a detection of the power spectrum of plausible reionization models, and with the advent of next-generation capabilities (e.g. the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometer Array Phase I Low) will move beyond the power spectrum to imaging of the EoR intergalactic medium. Such datasets provide context to galaxy evolution studies for the earliest galaxies on scales of tens of Mpc, but at present wide, deep galaxy surveys are lacking, and attaining the depth to survey the bulk of galaxies responsible for reionization will be challenging even for JWST. Thus we seek useful cross-correlations with other more direct tracers of the galaxy population. I review near-term prospects for cross-correlation studies with 21 cm and CO and CII emission, as well as future far-infrared misions suchas CALISTO.

  7. Studies of dished accelerator grids for 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Eighteen geometrically different sets of dished accelerator grids were tested on five 30-cm thrusters. The geometric variation of the grids included the grid-to-grid spacing, the screen and accelerator hole diameters and thicknesses, the screen and accelerator open area fractions, ratio of dish depth to dish diameter, compensation, and aperture shape. In general, the data taken over a range of beam currents for each grid set included the minimum total accelerating voltage required to extract a given beam current and the minimum accelerator grid voltage required to prevent electron backstreaming.

  8. Studies of dished accelerator grids for 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Geometrically different sets of dished accelerator grids were tested on five 30-cm thrusters. The geometric variation of the grids included the grid-to-grid spacing, the screen and accelerator hole diameters and thicknesses, the screen and accelerator open area fractions, ratio of dish depth to the dish diameter, compensation, and aperture shape. In general, the data taken over a range of beam currents for each grid set included the minimum total accelerating voltage required to extract a given beam current and the minimum accelerator grid voltage required to prevent electron backstreaming.

  9. Thermoacoustic imaging of fresh prostates up to 6-cm diameter

    NASA Astrophysics Data System (ADS)

    Patch, S. K.; Hanson, E.; Thomas, M.; Kelly, H.; Jacobsohn, K.; See, W. A.

    2013-03-01

    Thermoacoustic (TA) imaging provides a novel contrast mechanism that may enable visualization of cancerous lesions which are not robustly detected by current imaging modalities. Prostate cancer (PCa) is the most notorious example. Imaging entire prostate glands requires 6 cm depth penetration. We therefore excite TA signal using submicrosecond VHF pulses (100 MHz). We will present reconstructions of fresh prostates imaged in a well-controlled benchtop TA imaging system. Chilled glycine solution is used as acoustic couplant. The urethra is routinely visualized as signal dropout; surgical staples formed from 100-micron wide wire bent to 3 mm length generate strong positive signal.

  10. Deep depth undex simulator

    SciTech Connect

    Higginbotham, R. R.; Malakhoff, A.

    1985-01-29

    A deep depth underwater simulator is illustrated for determining the dual effects of nuclear type underwater explosion shockwaves and hydrostatic pressures on a test vessel while simulating, hydrostatically, that the test vessel is located at deep depths. The test vessel is positioned within a specially designed pressure vessel followed by pressurizing a fluid contained between the test and pressure vessels. The pressure vessel, with the test vessel suspended therein, is then placed in a body of water at a relatively shallow depth, and an explosive charge is detonated at a predetermined distance from the pressure vessel. The resulting shockwave is transmitted through the pressure vessel wall so that the shockwave impinging on the test vessel is representative of nuclear type explosive shockwaves transmitted to an underwater structure at great depths.

  11. Inflow measurements made with a laser velocimeter on a helicopter model in forward flight. Volume 4: Tapered planform blades at an advance ratio of 0.15

    NASA Technical Reports Server (NTRS)

    Althoff, Susan L.; Elliott, Joe W.; Sailey, Richard H.

    1988-01-01

    An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into the scale model helicopter rotor in forward flight (mu sub infinity = 0.15). The measurements were made with a two-component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 146 separate locations in order to clearly define the inflow character. This data is presented herein without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependent values are included as part of this report on two 5.25 inch floppy disks in MS-DOS format.

  12. (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Ceramics Synthesized by a Gel-Casting Method

    NASA Astrophysics Data System (ADS)

    Xiong, Wei

    2016-05-01

    (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) powder was synthesized by a solid-state reaction method, then the ceramics were fabricated by gel-casting and die-pressing routes, respectively. Piezoelectric coefficient (d 33 ) was measured by the d 33 m; Planar mode electromechanical coupling coefficient (k p ), dielectric loss (tanδ) and relative permittivity (ɛ r ) were measured by the impedance analyzer. Results of measurements showed that in the range of tested sintering temperature (1300-1500°C), gel-casting samples showed better piezoelectric and electromechanical coupling coefficients (d 33 = 395 pC/N, k p = 0.44) compared with die-pressing samples, and comparable dielectric properties were also observed. (tanδ = 0.037, ɛ r = 3267).

  13. Structure study of BaCe0.85Y0.15O3-Δ as solid state fuel cell material

    NASA Astrophysics Data System (ADS)

    Krezhov, K.; Vladikova, D.; Raikova, G.; Genov, I.; Malakova, T.; Dimitrov, D.; Svab, E.; Fabian, M.

    2016-03-01

    The structural details of powder, dense and porous samples of BaCe0.85Y0.15O3-δ (BCY15) used recently in an innovative monolithic design of SOFC were studied from multiple Rietveld analysis of neutron and x-ray diffraction patterns. The 3-layered monolithic assembly built from BCY15 material works as oxide ion conductor in the oxygen space, as proton conductor in the hydrogen area and as mixed conductor in the central membrane. We find that in all the samples of studied BCY15 based materials there are no indications of difference in crystallographic symmetry and the structure refinements did produce best agreement factors in orthorhombic Pnma space group.

  14. Inflow Measurements Made with a Laser Velocimeter on a Helicopter Model in Forward Flight. Volume 1: Rectangular Planform Blades at an Advance Ration of 0.15

    NASA Technical Reports Server (NTRS)

    Elliott, Joe W.; Althoff, Susan L.; Sailey, Richard H.

    1988-01-01

    An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley to measure the inflow into a scale model helicopter rotor in forward flight (microinf = 0.15). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 147 separate locations in order to clearly define the inflow character. This data is presented without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependent values are included as part of this report on two 5.25 inch floppy disks in Microsoft Corporation MS-DOS format.

  15. Debye’s temperature and heat capacity for Sr0.15Ba0.85Bi2Nb2O9 relaxor ferroelectric ceramic

    NASA Astrophysics Data System (ADS)

    Peláiz-Barranco, A.; González-Abreu, Y.; Saint-Grégoire, P.; Guerra, J. D. S.; Calderón-Piñar, F.

    2016-02-01

    A lead-free relaxor ferroelectric, Sr0.15Ba0.85Bi2Nb2O9, was synthesized via solid-state reaction and the temperature-dependence of the heat capacity was measured in a wide temperature range. The dielectric permittivity was also measured between 500Hz and 5MHz in the same temperature range. No anomaly has been detected in the heat capacity curve for the whole temperature range covered in the present experiments, while broad peaks have been observed in the dielectric permittivity with high frequency dispersion. A typical relaxor behavior has been observed from the dielectric analysis. The Debye’s temperature has showed a minimum value near the freezing temperature. The results are discussed considering the spin-glass model and the high frequency dispersion, which has been observed for the studied relaxor system.

  16. Strain Relaxation in Thin Films of La1.85Sr0.15CuO4 Grown by Pulsed Laser Deposition

    NASA Astrophysics Data System (ADS)

    Zaytseva, I.; Cieplak, M. Z.; Abal'Oshev, A.; Berkowski, M.; Domukhovski, V.; Paszkowicz, W.; Shalimov, A.

    2007-01-01

    X-ray diffraction, resistivity, and susceptibility measurements are used to examine the effects of film thickness d (from 17 to 250 nm) on the structural and superconducting properties of La1.85Sr0.15CuO4 films grown by pulsed laser deposition on SrLaAlO4 substrates. For each d the film sgrow with a variable strain, ranging from a large compressive strain in the thinnest films to a negligible or tensile strain in thick films. Our results indicate that the tensile strain is not caused by the off-stoichiometric layer at the substrate-film interface. Instead, it may be caused by the extreme oxygen deficiency in some of the films.

  17. Nonlinear structure-composition relationships in the Ge1-ySny/Si(100) (y<0.15) system

    SciTech Connect

    Beeler, R.; Roucka, R.; Chizmeshya, A. V. G.; Kouvetakis, J.; Menéndez, J.

    2011-07-26

    The compositional dependence of the cubic lattice parameter in Ge1-ySny alloys has been revisited. Large 1000-atom supercell ab initio simulations confirm earlier theoretical predictions that indicate a positive quadratic deviation from Vegard's law, albeit with a somewhat smaller bowing coefficient, θ = 0.047 Å, than found from 64-atom cell simulations (θ = 0.063 Å). On the other hand, measurements from an extensive set of alloy samples with compositions y < 0.15 reveal a negative deviation from Vegard's law. The discrepancy with earlier experimental data, which supported the theoretical results, is traced back to an unexpected compositional dependence of the residual strain after growth on Si substrates. The experimental bowing parameter for the relaxed lattice constant of the alloys is found to be θ = -0.066 Å. Possible reasons for the disagreement between theory and experiment are discussed in detail.

  18. (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Ceramics Synthesized by a Gel-Casting Method

    NASA Astrophysics Data System (ADS)

    Xiong, Wei

    2016-08-01

    (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) powder was synthesized by a solid-state reaction method, then the ceramics were fabricated by gel-casting and die-pressing routes, respectively. Piezoelectric coefficient ( d 33 ) was measured by the d 33 m; Planar mode electromechanical coupling coefficient ( k p ), dielectric loss ( tanδ) and relative permittivity ( ɛ r ) were measured by the impedance analyzer. Results of measurements showed that in the range of tested sintering temperature (1300-1500°C), gel-casting samples showed better piezoelectric and electromechanical coupling coefficients ( d 33 = 395 pC/N, k p = 0.44) compared with die-pressing samples, and comparable dielectric properties were also observed. ( tanδ = 0.037, ɛ r = 3267).

  19. Condyloma eradication: self-therapy with 0.15-0.5% podophyllotoxin versus 20-25% podophyllin preparations--an integrated safety assessment.

    PubMed

    Longstaff, E; von Krogh, G

    2001-04-01

    Topical application of podophyllin solution, long considered the therapy of first choice against condylomata acuminata, can no longer be recommended due to its low efficacy and gross toxicity. Self-treatment with 0.15-0.5% purified podophyllotoxin preparations, applied twice daily for 3 days, is now advocated as the alternative first-line therapy of choice, when significant improvement is conveniently, and cost-effectively, accomplished within a few weeks. This review provides a summary of the comparative efficacy and utility of podophyllin versus podophyllotoxin as well as a compilation of in vivo and in vitro safety evaluations. In light of overwhelming safety and efficacy data in favor of podophyllotoxin-derived products, it is concluded that podophyllin preparations have no place in the modern treatment portfolio for anogenital warts. PMID:11350195

  20. Characterization of phase transformation during hot compressive deformation in a β-stabilized Ti–45Al–7Nb–0.4W–0.15B alloy

    SciTech Connect

    Liu, Bin; Liu, Yong Huang, Lan; Li, Huizhong; He, Yuehui

    2015-07-15

    A β-stabilized Ti–45Al–7Nb–0.4W–0.15B (at.%) alloy was hot deformed by uniaxial compression and the phase evolution during the compression was characterized with X-ray diffraction, scanning electron microscopy and electron probe microanalysis. The results show that modest deformation stress during hot compression restrains the γ → α transformation and the decomposition of β phase. The restrained γ → α transformation is a result of a modified equilibrium of the γ and α phases due to the applied stress, and the restrained β decomposition is a kinetic effect due to the decelerated diffusion of β-stabilizing elements caused by the compressive stress. - Highlights: • In β-stabilized TiAl alloys, hot deformation has great influence on the equilibrium of the γ, α, and β phases. • Deformation restrains the γ → α transformation. • Deformation inhibits the decomposition of the β phase.

  1. Magnetoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 - CoFe2O4 particulate composites

    NASA Astrophysics Data System (ADS)

    Paul Praveen, J.; Vinitha Reddy, M.; Das, Dibakar

    2016-05-01

    0.7[(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3)]-0.3[CoFe2O4] multiferroic particulate ceramic composite with (0-3) connectivity has been synthesized by wet chemical methods. BCZT-CFO composite showed both polarization-electric field and magnetic hysteresis loops simultaneously at room temperature. A high dielectric constant of 2160 and tangent loss factor of 0.6 has been obtained. Magnetoelectric (ME) voltage coefficient (αME =dE/dH) of the composite was measured as a function of applied d.c magnetic field at different frequencies. At resonance frequency (365kHz) the composite showed a maximum αME of 102mV/cm.Oe. It was observed that the transverse ME coefficient is 1.8 times higher than the longitudinal ME coefficient. The magnetoelectric properties of this composite has been studied in detail in this work and correlated with its structure.

  2. Progress in Metal-Supported Axial-Injection Plasma Sprayed Solid Oxide Fuel Cells Using Nanostructured NiO-Y0.15Zr0.85O1.925 Dry Powder Anode Feedstock

    NASA Astrophysics Data System (ADS)

    Metcalfe, C.; Harris, J.; Kuhn, J.; Marr, M.; Kesler, O.

    2013-06-01

    A composite NiO-Y0.15Zr0.85O1.925 (YSZ) agglomerated feedstock having nanoscale NiO and YSZ primary particles was used to fabricate anodes having sub-micrometer structure. These anodes were incorporated into two different metal-supported SOFC architectures, which differ in the order of electrode deposition. The composition of the composite Ni-YSZ anodes is controllable by selection of the agglomerate size fraction and standoff distance, while the porosity is controllable by selection of agglomerate size fraction and addition of a sacrificial pore-forming material. A bi-layer anode was fabricated having a total porosity of 33% for the diffusion layer and 23% porosity for the functional layer. A power density of 630 mW/cm2 was obtained at 750 °C in humidified H2 with cells having the bi-layer anode deposited on the metal support. Cells having the cathode deposited on the metal support showed poor performance due to a significant number of vertical cracks through the electrolyte, allowing excessive gas cross-over between the anode and the cathode compartments.

  3. 8-cm mercury ion thruster system technology

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technology status of 8-cm diameter electron bombardment ion thrusters is presented. Much of the technology resulting from the 5-cm diameter thruster has been adapted and improved upon to increase the reliability, durability, and efficiency of the 8-cm thruster. Technology discussed includes: dependence of neutralizer tip erosion upon neutralizer flow rate; impregnated and rolled-foil insert cathode performance and life testing; neutralizer position studies; thruster ion beam profile measurements; high voltage pulse ignition; high utilization ion machined accelerator grids; deposition internal and external to the thruster; thruster vectoring systems; thruster cycling life testing and thruster system weights for typical mission applications.

  4. Structure and ferroelectric studies of (Ba{sub 0.85}Ca{sub 0.15})(Ti{sub 0.9}Zr{sub 0.1})O{sub 3} piezoelectric ceramics

    SciTech Connect

    Venkata Ramana, E.; Mahajan, A.; Graça, M.P.F.; Mendiratta, S.K.; Monteiro, J.M.; Valente, M.A.

    2013-10-15

    Graphical abstract: - Highlights: • (Ba{sub 0.85}Ca{sub 0.15})(Ti{sub 0.9}Zr{sub 0.1})O{sub 3} (BCTZO) ceramic was synthesized by the ceramic method. • In situ XRD and Raman spectra showed the phase transition of BCTZO around 360 K. • The ceramics showed a tunability of 82% at 40 kV cm{sup −1} electric field. • BCTZO exhibited good quality factor of 111 at microwave frequencies. • Piezoforce microscopy studies indicated the switchability of ferroelectric domains. - Abstract: We have synthesized and studied the structural and ferroelectric properties of lead-free 0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}–0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3} ceramics in the temperature region of its ferroelectric transition. The synthesized material showed high dielectric constant, low loss and good pyroelectric figure of merit. From the temperature dependent X-ray diffraction measurements, we determined the tricritical point to be in the temperature range of 303–400 K. The dielectric measurements indicate a diffuse ferroelectric phase transition (DPT) around 360 K in agreement with the X-ray measurements. We studied the evolution of Raman spectra with temperature to understand the nature of phase transition in BaTiO{sub 3} (BTO) and the BCTZO. The results indicates that the transition of ferroelectric–paraelectric state is not sharp as in the case of BTO and the polar state persists through the paraelectric state. In general, our study indicates that there are ferroelectric domains of nanometer size beyond the commonly defined transition temperature. The observation of local piezoelectric hysteresis loop indicated the existence of intrinsic ferroelectric property of the ceramic at the nanoscale. The ceramics exhibited electric field tunable dielectric properties with a tunability of 82% at an applied DC field of 40 kV cm{sup −1}, low dielectric loss of 0.001 and room temperature pyroelectric coefficient of 6 × 10{sup −8} C cm{sup −2} K{sup −1} and the

  5. Depth Optimization Study

    DOE Data Explorer

    Kawase, Mitsuhiro

    2009-11-22

    The zipped file contains a directory of data and routines used in the NNMREC turbine depth optimization study (Kawase et al., 2011), and calculation results thereof. For further info, please contact Mitsuhiro Kawase at kawase@uw.edu. Reference: Mitsuhiro Kawase, Patricia Beba, and Brian Fabien (2011), Finding an Optimal Placement Depth for a Tidal In-Stream Conversion Device in an Energetic, Baroclinic Tidal Channel, NNMREC Technical Report.

  6. Fluctuation conductivity and possible pseudogap state in FeAs-based superconductor EuFeAsO0.85F0.15

    NASA Astrophysics Data System (ADS)

    Solovjov, A. L.; Omelchenko, L. V.; Terekhov, A. V.; Rogacki, K.; Vovk, R. V.; Khlybov, E. P.; Chroneos, A.

    2016-07-01

    The study of excess conductivity σ \\prime (T) in the textured polycrystalline FeAs-based superconductor EuFeAsO0.85F0.15 ({T}{{c}}=11 {{K}}) prepared by the solid state synthesis is reported for the first time. The σ \\prime (T) analysis has been performed within the local pair (LP) model based on the assumption of the LPs formation in cuprate high-T c superconductors (cuprates) below the pseudogap (PG) temperature {T}* \\gg {T}{{c}}. Similarly to the cuprates, near {T}{{c}} σ \\prime (T) is adequately described by the 3D term of the Aslamasov–Larkin (AL) theory but the range of the 3D-AL fluctuations, {{Δ }}{T}3{{D}}, is relatively short. Above the crossover temperature {T}0≈ 11.7 {{K}} σ \\prime (T) is described by the 2D Maki–Thompson (MT) fluctuation term of the Hikami–Larkin theory. But enhanced 2D-MT fluctuation contribution being typical for the magnetic superconductors is observed. Within the LP model the PG parameter, {{{Δ }}}* (T), was determined for the first time. It is shown that {{{Δ }}}* (T) demonstrates the narrow maximum at {T}s≈ 160 {{K}} followed by the descending linear length down to {T}{SDW}={T}{NFe}≈ 133 {{K}}. Observed small {{Δ }}{T}3{{D}}, enlarged 2D σ \\prime (T) and linear {{{Δ }}}* (T) are considered to be the evidence of the enhanced magnetic interaction in EuFeAsO0.85F0.15. Importantly, the slop of the linear {{{Δ }}}* (T) and its length are found to be the same as it is revealed for SmFeAsO0.85. The results suggest both the similarity of the magnetic interaction processes in different Fe-pnictides and applicability of the LP model to the σ \\prime (T) analysis even in magnetic superconductors.

  7. Suppression of superconductivity in La1.85Sr0.15Cu1-yNiyO4: The relevance of local lattice distortions

    NASA Astrophysics Data System (ADS)

    Haskel, D.; Stern, E. A.; Polinger, V.; Dogan, F.

    2001-02-01

    The effect of Ni substitution upon the local structure of La1.85Sr0.15Cu1-yNiyO4 is commonly neglected when addressing the Ni-induced destruction of the superconducting state at y≈0.03 and a metal-insulator transition at y≈0.05. It is also sometimes assumed that direct substitution of a dopant into the CuO2 planes has a detrimental effect on superconductivity due to in-plane lattice distortions around the dopants. We present here results from angular-dependent x-ray absorption fine structure (XAFS) measurements at the Ni, La and Sr K-edges of oriented powders of La1.85Sr0.15Cu1-yNiyO4 with y=0.01, 0.03, 0.06. A special magnetic alignment geometry allowed us to measure pure ĉ and ab̂ oriented XAFS at the Ni K-edge in identical fluorescence geometries. Both the near-edge absorption spectra (XANES) and the XAFS unequivocally show that the NiO6 octahedra are largely contracted along the c-axis, by ≈ 0.16 Å. Surprisingly, the Ni-O planar bonds and the Ni-O-Cu/Ni planar buckling angle are nearly identical to their Cu counterparts. The NiO6 octahedral contraction drives the macroscopic ĉ-axis contraction observed with Ni-doping. The local ĉ-axis strongly fluctuates, due to the different NiO6 and CuO6 octahedral configurations and the much stronger bonding of a La+3 ion than a Sr+2 ion to the O(2) apical oxygens. We discuss the relevance of these findings to the mechanisms of Tc suppresion and hole-localization by Ni dopants.

  8. Impacts of Soil Warming and Plant Rhizosphere on Root Litter Decomposition at Different Soil Depths in a Mediterranuan Grassland Lysimeter Facility

    NASA Astrophysics Data System (ADS)

    Zhu, B.; Hicks Pries, C.; Castanha, C.; Curtis, J. B.; Porras, R. C.; Torn, M. S.

    2014-12-01

    Accurate understanding of soil carbon cycling is critical for predicting climate-ecosystem feedbacks. Decomposition of root litter and its transformation into soil organic matter (SOM) are critical processes of soil carbon cycling. We aim to study the impacts of soil warming and plant rhizosphere on the fate of 13C-labeled roots buried at two soil depths using a field lysimeter facility at Hopland, California. The lysimeters contain soil columns of 38-cm diameter and 48-cm depth (0-15 cm A-horizon, and 15-48 cm B-horizon, Laughlin soil series) sown with annual grasses dominated by Avena barbata. The experiment has three treatments (planted-ambient, planted-warming (+4°C), and unplanted-ambient). In February 2014, 13C-labeled A. fatua roots were added to two depths (8-12 and 38-42 cm). We measured root-derived 13C in respired CO2 collected at the soil surface and in leachate dissolved organic carbon (DOC) collected from the lysimeters during the growing season and in soil harvested in August 2014. We found (1) soil temperature at two depths (10- and 40-cm) have been elevated by 4±0.2°C in the warmed compared to the ambient lysimeters; (2) surface (10-cm) volumetric soil moisture followed this order (unplanted-ambient > planted-ambient > planted-warming), while subsurface (40-cm) soil moisture showed little variation among treatments; (3) ecosystem respiration was enhanced by soil warming during the early growing season (March 15th and April 5th) when soil moisture was not limiting (>20%), while it was suppressed by soil warming during the late growing season (May 7th) when soil moisture was limiting (<20%), and was not significantly different among treatments towards the end of growing season (May 20th); and (4) aboveground plant biomass increased 25% with soil warming. More data including 13C values of ecosystem respiration, DOC loss, and harvested soil samples, as well as soil nutrient supply rates, microbial biomass and community structure will be presented

  9. Chilled Mirror Dew Point Hygrometer (CM) Handbook

    SciTech Connect

    Ritsche, MT

    2005-01-01

    The CM systems have been developed for the ARM Program to act as a moisture standard traceable to National Institute of Standards and Technology (NIST). There are three CM systems that are each fully portable, self-contained, and require only 110 V AC power. The systems include a CM sensor, air sampling and filtration system, a secondary reference (Rotronic HP043 temperature and relative humidity sensor) to detect system malfunctions, a data acquisition system, and data storage for more than one month of 1-minute data. The CM sensor directly measures dew point temperature at 1 m, air temperature at 2 m, and relative humidity at 2 m. These measurements are intended to represent self-standing data streams that can be used independently or in combinations.

  10. Astrophysics with the 60-cm telescope

    NASA Astrophysics Data System (ADS)

    Zverko, J.

    2014-03-01

    Observational programs and selection from scientific results with the 60-cm telescope achieved at the Skalnaté Pleso Observatory since its putting into operation is reviewed: novae, eclipsing and interacting binaries, symbiotic stars, cataclysmic variables, chemically peculiar stars, comets. Possible targets among newly detected binaries are proposed for determining orbital parameters using the new spectrograph of the 60-cm telescope at the Stará Lesná Observatory.

  11. A new method to enlarge a range of continuously perceived depth in DFD (depth-fused 3D) display

    NASA Astrophysics Data System (ADS)

    Tsunakawa, Atsuhiro; Soumiya, Tomoki; Horikawa, Yuta; Yamamoto, Hirotsugu; Suyama, Shiro

    2013-03-01

    We can successfully solve the problem in DFD display that the maximum depth difference of front and rear planes is limited because depth fusing from front and rear images to one 3-D image becomes impossible. The range of continuously perceived depth was estimated as depth difference of front and rear planes increases. When the distance was large enough, perceived depth was near front plane at 0~40 % of rear luminance and near rear plane at 60~100 % of rear luminance. This maximum depth range can be successfully enlarged by spatial-frequency modulation of front and rear images. The change of perceived depth dependence was evaluated when high frequency component of front and rear images is cut off using Fourier Transformation at the distance between front and rear plane of 5 and 10 cm (4.9 and 9.4 minute of arc). When high frequency component does not cut off enough at the distance of 5 cm, perceived depth was separated to near front plane and near rear plane. However, when the images are blurred enough by cutting high frequency component, the perceived depth has a linear dependency on luminance ratio. When the images are not blurred at the distance of 10 cm, perceived depth is separated to near front plane at 0~30% of rear luminance, near rear plane at 80~100 % and near midpoint at 40~70 %. However, when the images are blurred enough, perceived depth successfully has a linear dependency on luminance ratio.

  12. Strain accommodation through facet matching in La{sub 1.85}Sr{sub 0.15}CuO{sub 4}/Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4} ramp-edge junctions

    SciTech Connect

    Hoek, M.; Coneri, F.; Poccia, N.; Renshaw Wang, X.; Hilgenkamp, H.; Ke, X.; Van Tendeloo, G.

    2015-08-01

    Scanning nano-focused X-ray diffraction and high-angle annular dark-field scanning transmission electron microscopy are used to investigate the crystal structure of ramp-edge junctions between superconducting electron-doped Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4} and superconducting hole-doped La{sub 1.85}Sr{sub 0.15}CuO{sub 4} thin films, the latter being the top layer. On the ramp, a new growth mode of La{sub 1.85}Sr{sub 0.15}CuO{sub 4} with a 3.3° tilt of the c-axis is found. We explain the tilt by developing a strain accommodation model that relies on facet matching, dictated by the ramp angle, indicating that a coherent domain boundary is formed at the interface. The possible implications of this growth mode for the creation of artificial domains in morphotropic materials are discussed.

  13. Correlated alteration effects in CM carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Browning, Lauren B.; McSween, Harry Y., Jr.; Zolensky, Michael E.

    1996-07-01

    Three parameters are proposed to determine the relative extent of alteration in CM chondrites. The mineralogic alteration index monitors the relative progress of coupled substitutions in the progressive alteration of cronstedtite to Mg-serpentine and increases with increasing alteration. To calculate values of this index, an algorithm has been developed to estimate the average matrix phyllosilicate composition in individual CM chondrites. The second parameter is the volume percent of isolated matrix silicates, which decreases with progressive alteration due to mineral hydration. Finally, the volume percent of chondrule alteration monitors the extent of chondrule phyllosilicate production and increases as alteration proceeds. These parameters define the first CM alteration scale that relies on multiple indicators of progressive alteration. The following relative order of increasing alteration is established by this model: Murchison ≤ Bells < Pollen ≤ Murray < Mighei < Nogoya < Cold Bokkeveld. The relative degree of aqueous processing Cochabamba and Boriskino experienced is less precisely constrained, although both fall near the middle of this sequence. A comparison between the mineralogic alteration index and literature values for the whole-rock chemistry of CM chondrites reveals several correlations. A positive, nearly linear correlation between bulk H content and progressive CM alteration suggests an approximately constant production rate of new phyllosilicates relative to the mineralogical transition from cronstedtite to Mg-serpentine. The abundance of trapped planetary 36Ar decreases systematically in progressively altered CM chondrites, suggesting the wholesale destruction of primary noble gas carrier phase (s) by aqueous reactions. Because low temperature fluid-rock reactions are generally associated with large isotopic mass fractionation factors, we also compared our model predictions with δ18O values for bulk CM samples. Although some of these data are

  14. Correlated Alteration Effects in CM Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Zolensky, Michael E.; Browning, Lauren B.; McSween, Harry Y., Jr.

    1996-01-01

    Three parameters are proposed to determine the relative extent of alteration in CM chondrites. The mineralogic alteration index monitors the relative progress of coupled substitutions in the progressive alteration of cronstedtite to Mg-serpentine, and increases with increasing alteration. To calculate values of this index, an algorithm has been developed to estimate the average matrix phyllosilicate composition in individual CM chondrites. The second parameter is the volume percent of isolated matrix silicates, which decreases with progressive alteration due to mineral hydration. Finally, the volume percent of chondrule alteration monitors the extent of chondrule phyllosilicate production, and increases as alteration proceeds. These parameters define the first CM alteration scale that-relies on multiple indicators of progressive alteration. The following relative order of increasing alteration is established by this model: Murchison less than or equal to Bells less than Pollen less than or equal to Murray less than Mighei less than Nogoya less than Cold Bokkeveld. Bulk delta18O values generally increase with progressive alteration, providing additional support for this sequence. The relative degree of aqueous processing Cochabamba and Boriskino experienced is less precisely constrained, although both fall near the middle of this sequence. A comparison between the mineralogic alteration index and literature values of the whole-rock chemistry of CM chondrites reveals several correlations. For example, a positive, nearly linear correlation between bulk H content and progressive CM alteration suggests an approximately constant production rate of new phyllosilicates relative to the mineralogical transition from cronstedtite to Mg-serpentine. Furthermore, the abundance of trapped planetary Ar-36 decreases systematically in progressively altered CM chondrites, suggesting the wholesale destruction of primary noble gas carrier phase(s) by aqueous reactions. Multiple

  15. Detection of Thermal 2 cm and 1 cm Formaldehyde Emission in NGC 7538

    NASA Astrophysics Data System (ADS)

    Yuan, Liang; Araya, E. D.; Hofner, P.; Kurtz, S.; Pihlstrom, Y.

    2011-05-01

    Formaldehyde is a tracer of high density gas in massive star forming regions. The K-doublet lines from the three lowest rotational energy levels of ortho-formaldehyde correspond to wavelengths of 6, 2 and 1 cm. Thermal emission of these transitions is rare, and maser emission has only been detected in the 6 cm line. NGC 7538 is an active site of massive star formation in the Galaxy, and one of only a few regions known to harbor 6 cm formaldehyde (H2CO) masers. Using the NRAO 100 m Green Bank Telescope (GBT), we detected 2 cm H2CO emission toward NGC 7538 IRS1. The velocity of the 2 cm H2CO line is very similar to the velocity of one of the 6 cm H2CO masers but the linewidth is greater. To investigate the nature of the 2 cm emission, we conducted observations of the 1 cm H2CO transition, and obtained a cross-scan map of the 2 cm line. We detected 1 cm emission and found that the 2 cm emission is extended (greater than 30"), which implies brightness temperatures of ˜0.2 K. Assuming optically thin emission, LTE, and that the 1 cm and 2 cm lines originate from the same volume of gas, both these detections are consistent with thermal emission of gas at ˜30 K. We conclude that the 1 cm and 2 cm H2CO lines detected with the GBT are thermal, which implies molecular densities above ˜105 cm-3. LY acknowledges support from WIU. PH acknowledges partial support from NSF grant AST-0908901.

  16. Radon depth migration

    SciTech Connect

    Hildebrand, S.T. ); Carroll, R.J. )

    1993-02-01

    A depth migration method is presented that used Radon-transformed common-source seismograms as input. It is shown that the Radon depth migration method can be extended to spatially varying velocity depth models by using asymptotic ray theory (ART) to construct wavefield continuation operators. These operators downward continue an incident receiver-array plane wave and an assumed point-source wavefield into the subsurface. The migration velocity model is constrain to have longer characteristic wavelengths than the dominant source wavelength such that the ART approximations for the continuation operators are valid. This method is used successfully to migrate two synthetic data examples: (1) a point diffractor, and (2) a dipping layer and syncline interface model. It is shown that the Radon migration method has a computational advantage over the standard Kirchhoff migration method in that fewer rays are computed in a main memory implementation.

  17. Depth from water reflection.

    PubMed

    Linjie Yang; Jianzhuang Liu; Xiaoou Tang

    2015-04-01

    The scene in a water reflection image often exhibits bilateral symmetry. In this paper, we design a framework to reconstruct the depth from a single water reflection image. This problem can be regarded as a special case of two-view stereo vision. It is challenging to obtain correspondences from the real scene and the mirror scene due to their large appearance difference. We first propose an appearance adaptation method to transform the appearance of the mirror scene so that it is much closer to the real scene. We then present a stereo matching algorithm to obtain the disparity map of the real scene. Compared with other depth-from-symmetry work that deals with man-made objects, our algorithm can recover the depth maps of a variety of scenes, where both natural and man-made objects may exist. PMID:25643408

  18. Probing lepton asymmetry with 21 cm fluctuations

    SciTech Connect

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: oyamayo@post.kek.jp E-mail: tomot@cc.saga-u.ac.jp

    2014-09-01

    We investigate the issue of how accurately we can constrain the lepton number asymmetry ξ{sub ν}=μ{sub ν}/T{sub ν} in the Universe by using future observations of 21 cm line fluctuations and cosmic microwave background (CMB). We find that combinations of the 21 cm line and the CMB observations can constrain the lepton asymmetry better than big-bang nucleosynthesis (BBN). Additionally, we also discuss constraints on ξ{sub ν} in the presence of some extra radiation, and show that the 21 cm line observations can substantially improve the constraints obtained by CMB alone, and allow us to distinguish the effects of the lepton asymmetry from the ones of extra radiation.

  19. CV and CM chondrite impact melts

    NASA Astrophysics Data System (ADS)

    Lunning, Nicole G.; Corrigan, Catherine M.; McSween, Harry Y.; Tenner, Travis J.; Kita, Noriko T.; Bodnar, Robert J.

    2016-09-01

    Volatile-rich and typically oxidized carbonaceous chondrites, such as CV and CM chondrites, potentially respond to impacts differently than do other chondritic materials. Understanding impact melting of carbonaceous chondrites has been hampered by the dearth of recognized impact melt samples. In this study we identify five carbonaceous chondrite impact melt clasts in three host meteorites: a CV3red chondrite, a CV3oxA chondrite, and a regolithic howardite. The impact melt clasts in these meteorites respectively formed from CV3red chondrite, CV3oxA chondrite, and CM chondrite protoliths. We identified these impact melt clasts and interpreted their precursors based on their texture, mineral chemistry, silicate bulk elemental composition, and in the case of the CM chondrite impact melt clast, in situ measurement of oxygen three-isotope signatures in olivine. These impact melts typically contain euhedral-subhedral olivine microphenocrysts, sometimes with relict cores, in glassy groundmasses. Based on petrography and Raman spectroscopy, four of the impact melt clasts exhibit evidence for volatile loss: these melt clasts either contain vesicles or are depleted in H2O relative to their precursors. Volatile loss (i.e., H2O) may have reduced the redox state of the CM chondrite impact melt clast. The clasts that formed from the more oxidized precursors (CV3oxA and CM chondrites) exhibit phase and bulk silicate elemental compositions consistent with higher intrinsic oxygen fugacities relative to the clast that formed from a more reduced precursor (CV3red chondrite). The mineral chemistries and assemblages of the CV and CM chondrite impact melt clasts identified here provide a template for recognizing carbonaceous chondrite impact melts on the surfaces of asteroids.

  20. Depth remapping using seam carving for depth image based rendering

    NASA Astrophysics Data System (ADS)

    Tsubaki, Ikuko; Iwauchi, Kenichi

    2015-03-01

    Depth remapping is a technique to control depth range of stereo images. Conventional remapping which uses a transform function in the whole image has a stable characteristic, however it sometimes reduces the 3D appearance too much. To cope with this problem, a depth remapping method which preserves the details of depth structure is proposed. We apply seam carving, which is an effective technique for image retargeting, to depth remapping. An extended depth map is defined as a space-depth volume, and a seam surface which is a 2D monotonic and connected manifold is introduced. The depth range is reduced by removing depth values on the seam surface from the space-depth volume. Finally a stereo image pair is synthesized from the corrected depth map and an input color image by depth image based rendering.

  1. Study of surface cross-hatch and misfit dislocation structure in In(0.15)Ga(0.85)As/GaAs grown by chemical beam epitaxy

    NASA Astrophysics Data System (ADS)

    Beanland, R.; Aindow, M.; Joyce, T. B.; Kidd, P.; Lourenco, M.; Goodhew, P. J.

    1995-04-01

    It is well known that a cross-hatch develops on the surface of low-misfit strained semiconductor layers which undergo relaxation by the introduction of arrays of a/2(101) misfit dislocations in the interface between the strained layer and substrate. Here we present a study of the detailed structure of these surface striations and their development with thickness in a series of In(x)Ga(1-x)As single layers on (001)GaAs, where x is close to 0.15. Using atomic force microscopy, it is found that the striations are in fact almost triangular ridges with rounded tops separated by V-shaped grooves. They are not slip traces. These ridges are found to be asymmetric in distribution, with those parallel to (1(bar)10) far higher than those parallel to (110). The spacing and height of the ridges increases with layer thickness. The structure also becomes more disordered in the case of thicker layers, with ridges running for shorter lengths and having more complex profiles. Using transmission electron microscopy, it is possible to link the ridges to dislocations lying above, and parallel to, the interface which result from repeated operation of multiplication sources.

  2. Microstructures of La 1.85Sr 0.15CuO 4 doped with Ni at high doping level

    NASA Astrophysics Data System (ADS)

    Wu, X. S.; Jiang, S. S.; Pan, F. M.; Lin, J.; Xu, N.; Mao Zhiqiang; Xu Gaoji; Zhang Yuheng

    1996-02-01

    Ceramic superconductors of La 1.85Sr 0.15Cu 1- yNi yO 4 with 0.00 ≤ y ≤ 0.50 were synthesized. There is no impurity phase detected in the entire Ni doped region. The structure of these Ni-doped samples was characterized by X-ray diffraction studies. The atomic structural parameters were obtained by Rietveld refinements for the Ni-doped samples with y ≤ 0.50. Some meaningful bond distances were determined according to the refined results. According to the variations of some bond distances with y, the whole doping range could be divided into two regions: low doping level (LDL) and high doping level (HDL). The bond length between the two apical oxygen atoms in the CuO 6 octahedra for the Ni-doped samples increased with increasing content of Ni in the LDL, and decreased in the HDL. The average bond distance of LaO was not changed in the whole doping region. The metal-insulator transition was also observed in this Ni-doped system.

  3. Experimental investigation of a 0.15 scale model of a conformal variable-ramp inlet for the F-16 airplane

    NASA Technical Reports Server (NTRS)

    Hawkins, J. E.

    1980-01-01

    A 0.15 scale model of a proposed conformal variable-ramp inlet for the Multirole Fighter was tested from Mach 0.8 to 2.2 at a wide range of angles of attack and sideslip. Inlet ramp angle was varied to optimize ramp angle as a function of engine airflow, Mach number, angle of attack, and angle of sideslip. Several inlet configuration options were investigated to study their effects on inlet operation and to establish the final flight configuration. These variations were cowl sidewall cutback, cowl lip bluntness, boundary layer bleed, and first-ramp leading edge shape. Diagnostic and engine face instrumentation were used to evaluate inlet operation at various inlet stations and at the inlet/engine interface. Pressure recovery and stability of the inlet were satisfactory for the proposed application. On the basis of an engine stability audit of the worst-case instantaneous distortion patterns, no inlet/engine compatibility problems are expected for normal operations.

  4. Fatigue Crack Propagation in Intercritically Tempered Fe-9Ni-0.1C and Fe-4Mn-0.15C

    NASA Astrophysics Data System (ADS)

    Choi, H. J.; Schwartz, L. H.

    1983-06-01

    Fatigue crack propagation was studied for two intercritically tempered cryogenic steels, Fe-9Ni-0.1C and Fe-4Mn-0.15C, at both intermediate (stage II) and low (stage I, near threshold) stress intensity ranges. Propagation rates were determined for varying intercritical tempering times corresponding to varying amounts of retained austenite and untempered martensite. The results show that the heat treatments that optimize impact fracture properties in the nickel steel are also beneficial with respect to the fatigue crack propagation rate in stage I, while no beneficial effect beyond that attributable to carbon redistribution was observed for stage II. For the manganese steel, heat treatments leading to increased concentrations of retained austenite also increased the threshold stress even though no improvement in fracture toughness was observed. To clarify the origin of this improved behavior, the fracture surface was analyzed by Mössbauer Spectroscopy and Auger Electron Microprobe. The Mössbauer results indicated that the retained austenite in the crack path is transformed to martensite as was earlier shown in this laboratory for Charpy specimens. Auger composition analysis suggested a tendency for a stage I crack tip to avoid the mechanically induced brittle untempered martensite in the Fe-Mn steel, while no such preference was observed for stage II.

  5. Effect of phosphorus additions on the sintering and transport properties of proton conducting BaZr0.85Y0.15O3-δ

    NASA Astrophysics Data System (ADS)

    Soares, H. S.; Zhang, X.; Antunes, I.; Frade, J. R.; Mather, G. C.; Fagg, D. P.

    2012-07-01

    The influence of phosphorous additions on the sintering and electrical transport properties of the proton-conducting perovskite BaZr0.85Y0.15O3-δ (BZY) has been studied with a view to the use of phosphates as typical dispersants for the formation of stabilised solid suspensions or as possible sintering aids. P2O5 additions, (1-x)BZY·xP2O5, monotonously promote densification in the intermediate compositional range 0.04≤x≤0.08. Nonetheless, BZY reacts with phosphorous forming the phase Ba3(PO4)2 at temperatures as low as 600 °C. The associated loss of Ba from the perovskite, leads to a decrease in the perovskite lattice parameter, the formation of yttria-based impurity phases and impaired grain growth. Such reaction has an extremely detrimental effect on bulk and grain boundary conductivities. It is, therefore, vital that the current results are taken into account by the protonics community when attempting to prepare the stabilised solid suspensions of BZY nanopowders required for thin ceramic applications. Alternative dispersants to phosphate esters must be found.

  6. Damage development during low cycle fatigue of carbon-black loaded SBR. [Styrene butadiene rubber containing 0, 15, 25, and 35 wt % carbon black

    SciTech Connect

    Lesuer, D.; Goldberg, A.; Hiromoto, D.; Patt, J.

    1984-06-18

    Fatigue of elastomers is a subject that has received considerable study over the years. This paper explores the problem of damage accumulation in a series of styrene butadiene rubber (SBR) based compounds containing 0, 15, 25, and 35 wt % carbon-black under conditions in which a limited number of higher stress cycles have been applied to the material (referred to here as low cycle fatigue). Damage development in elastomers can take many forms. Generally speaking, one can classify the degradation as mechanical or chemical in origin. The most obvious form of mechanical damage is flaw or cut growth, while typical examples of chemical damage include chain scission or thermal oxidation. The fatigue crack growth relationship given in Equation 1 obviously only applies to flaw growth. However, it does an excellent job of following the data and exhibits the threshold behavior observed in both SBR and SBR-35 at room temperature. At higher temperatures, the damaged material shows an increasing deviation from threshold behavior. The obvious implication is that some thermally activated damage mechanism is degrading the material. In previous work, carbon-black loaded SBR subjected to a high temperature, high stress environment was shown to undergo a thermal-mechanical oxidation process. Certainly, this process is a candidate for a damage mechanism in these studies. 6 references, 14 figures, 1 table.

  7. Synthesis and Characterization of Ba(Zr0.15Ti0.85)O3 Nano Powders by Oxalate Precipitation Method

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Wang, Xiaohui; Qiao, Bin; Gui, Zhilun; Li, Longtu

    2006-08-01

    Barium zirconate titanate (BZT) is considered to be an important dielectric material for the fabrication of multilayer ceramic capacitors (MLCCs). The synthesis of nanocrystalline powders of high purity is the key to improving the performance of BZT-based ceramics. In this study, we developed Ba(Zr0.15Ti0.85)O3 nano powders with a perovskite structure and a homogeneous granularity through the oxalate precipitation method. The average particle size of the powders can be controlled from 30 to 100 nm at different calcining temperatures. The sintering property of the powders is superior to that of powders prepared by the conventional solid-state method, such that the more compact ceramics with a smaller grain size can be obtained at a sintering temperature of 1250 °C. The dielectric property of the ferroelectric-powder-based ceramics was so excellent for the development of dielectric materials for base-metal electrode multilayer ceramic capacitors (BME MLCCs) with a large capacitance.

  8. Oxygen nonstoichiometry of tetragonal La2-xSr(x)CuO4-δ (x = 0.15-1.2) and in situ XPS studies at elevated temperatures.

    PubMed

    Alyoshin, V A; Romanova, I P; Mikhailova, D; Oswald, S; Senyshyn, A; Ehrenberg, H

    2010-12-30

    The peculiarities of oxygen nonstoichiometry (δ) in tetragonal La(2-x)Sr(x)CuO(4-δ) solid solution with x(Sr) = 0.15-1.2 were studied by XRD, NPD, in situ high-temperature XPS, and chemical analysis. Temperature dependences of oxygen nonstoichiometry, δ = δ(T), were obtained for different Sr contents at 1 bar of O(2). Two types of charge compensation during replacement of lanthanum by strontium are discussed: an increase of the average copper oxidation state and a formation of oxygen vacancies. The average copper oxidation state V(Cu) exhibits a maximum of 2.32 at x(Sr) = 0.6, while δ increases with x(Sr). Oxygen vacancies are unambiguously located on the 4c site ({CuO(2)} plane) for compositions with different strontium contents, which electronic state is described by the O 2p core electron peak at about 531 eV. Thermal stability of the solid solution in a vacuum is associated with the extraction of practically the entire oxygen from CuO(2) layers and the formation of Cu(+) at least in the near-surface region. The higher average copper oxidation state after synthesis in the Sr-rich phases in comparison with the Sr-poor compositions prevents oxygen removal and the formation of Cu(+) and, therefore, stabilizes the structure during heating in a vacuum. PMID:21133400

  9. Anisotropy of the upper critical fields and the paramagnetic Meissner effect in La1.85Sr0.15CuO4 single crystals

    NASA Astrophysics Data System (ADS)

    Felner, I.; Tsindlekht, M. I.; Drachuck, G.; Keren, A.

    2013-02-01

    Optimally doped La1.85Sr0.15CuO4 single crystals have been investigated by dc and ac magnetic measurements. These crystals have rectangular needle-like shapes with the long needle axis parallel to the crystallographic c axis (c-crystal) or parallel to the basal planes (a-crystal). In both crystals, the temperature dependence of the upper critical fields (HC2) and the surface critical field (HC3) were measured. The H-T phase diagram is presented. Close to TC = 35 K, for the c-crystal, {\\boldsymbol{\\gamma}}^{c}={H}_{{C3}}^{c}/{H}_{{C2}}^{c}=1.8 0(2), whereas for the a-crystal the {\\boldsymbol{\\gamma}}^{a}={H}_{{C3}}^{a}/{H}_{{C2}}^{a}=4.0(2) obtained is much higher than 1.69, predicted by the ideal mathematical model. At low applied dc fields, positive field-cooled branches known as the ‘paramagnetic Meissner effect’ (PME) are observed; their magnitude is inversely proportional to H. The anisotropic PME is observed in both a- and c-crystals, only when the applied field is along the basal planes. It is speculated that the high γa and the PME are connected to each other.

  10. Anisotropy of the upper critical fields and the paramagnetic Meissner effect in La1.85Sr0.15CuO4 single crystals.

    PubMed

    Felner, I; Tsindlekht, M I; Drachuck, G; Keren, A

    2013-02-13

    Optimally doped La(1.85)Sr(0.15)CuO(4) single crystals have been investigated by dc and ac magnetic measurements. These crystals have rectangular needle-like shapes with the long needle axis parallel to the crystallographic c axis (c-crystal) or parallel to the basal planes (a-crystal). In both crystals, the temperature dependence of the upper critical fields (H(C2)) and the surface critical field (H(C3)) were measured. The H-T phase diagram is presented. Close to T(C) = 35 K, for the c-crystal, γ(C) = H(C3)(c)/H(C2)(c) = 1.80(2), whereas for the a-crystal the γ(a) = H(C3)(a)/H(C2)(a) = 4.0(2) obtained is much higher than 1.69, predicted by the ideal mathematical model. At low applied dc fields, positive field-cooled branches known as the 'paramagnetic Meissner effect' (PME) are observed; their magnitude is inversely proportional to H. The anisotropic PME is observed in both a- and c-crystals, only when the applied field is along the basal planes. It is speculated that the high γ(a) and the PME are connected to each other. PMID:23315336

  11. Electrical and Structural Real-Time Changes in Thin Thermoelectric (Bi0.15Sb0.85)2Te3 Films by Dynamic Thermal Treatment

    NASA Astrophysics Data System (ADS)

    Rothe, K.; Stordeur, M.; Heyroth, F.; Syrowatka, F.; Leipner, H. S.

    2010-09-01

    A recent trend in thermoelectrics is miniaturization of generators or Peltier coolers using the broad spectrum of thin-film and nanotechnologies. Power supplies for energy self-sufficient micro and sensor systems are a wide application field for such generators. It is well known that thermal treatment of as-deposited p-type (Bi0.15Sb0.85)2Te3 films leads to enhancement of their power factors. Whereas up to now only the start (as-deposited) and the end (after annealing) film stages were investigated, herein for the first time, the dynamical changes of sputter-deposited film properties have been observed by real-time measurements. The electrical conductivity shows a distinct, irreversible increase during a thermal cycle of heating to about 320°C followed by cooling to room temperature. The interpretation of the Seebeck and Hall coefficients points to an enhancement in Hall mobility after annealing. In situ x-ray diffractometry shows the generation of an additional Te phase depending on temperature. This is also confirmed by energy-dispersive x-ray microanalysis and the corresponding mapping by scanning electron microscopy. It is presumed that the Te enrichment in a separate, locally well-defined phase is the reason for the improvement in the integral film transport properties.

  12. Zn0.85Cd0.15Se active layers on graded-composition InxGa1-xAs buffer layers

    NASA Astrophysics Data System (ADS)

    Müller, B. H.; Lantier, R.; Sorba, L.; Heun, S.; Rubini, S.; Lazzarino, M.; Franciosi, A.; Napolitani, E.; Romanato, F.; Drigo, A. V.; Lazzarini, L.; Salviati, G.

    1999-06-01

    We investigated the structural and optical properties of Zn0.85Cd0.15Se epilayers for blue optical emission on lattice-matched InxGa1-xAs buffer layers. Both the II-VI layers and the III-V buffers were grown by molecular beam epitaxy on GaAs(001) wafers. A parabolic In concentration profile within the graded-composition InxGa1-xAs buffers was selected to control strain relaxation and minimize the concentration of threading dislocations. Dislocation-free II-VI growth was readily achieved on the graded buffers, with a Rutherford backscattering yield ratio reduced by a factor of 3 and a deep-level emission intensity reduced by over two orders of magnitude relative to those observed following direct II-VI growth on GaAs. The surface morphology of the materials, however, was found to replicate the crosshatched pattern of the underlying InxGa1-xAs substrates.

  13. Pressure dependence of the electronic structure of a [311] piezoelectric Ga0.85In0.15As/AlAs superlattice

    NASA Astrophysics Data System (ADS)

    Reparaz, J. S.; Muniz, L. R.; Goñi, A. R.; Alonso, M. I.; Rozas, G.; Fainstein, A.; Saravanan, S.; Vaccaro, P. O.

    2010-09-01

    We have studied the electronic subband structure of a piezoelectric [311] Ga0.85In0.15As/AlAs superlattice by means of high-hydrostatic pressure and excitation-power-dependent photoluminescence at 78 K. In particular, we unraveled the origin of two optical transitions at around 1.96 and 2 eV at ambient pressure, which were recently found to give rise to an unexpectedly strong resonant enhancement of the acoustic-phonon Raman scattering for such samples with permanent built-in piezoelectric fields [G. Rozas , Phys. Rev. B 77, 165314 (2008)10.1103/PhysRevB.77.165314]. Here we demonstrate that these transitions are doubly indirect, in real and reciprocal space, corresponding to radiative recombination processes between electrons at the X valleys of the AlAs barriers and heavy holes at the Γ point of the Brillouin zone but confined to the GaInAs quantum wells. In addition, the partial screening of the piezoelectric field induced by carrier photoexcitation under illumination becomes largely suppressed for pressures above 1.1 GPa due to conduction-band Γ-X crossover effects.

  14. Crystal structure, magnetism, and superconductivity of YBa2(Cu1-xFex)3O7+y with x=0.05-0.15

    NASA Astrophysics Data System (ADS)

    Katano, S.; Matsumoto, T.; Matsushita, A.; Hatano, T.; Funahashi, S.

    1990-02-01

    Neutron scattering experiments and magnetic-susceptibility measurements have been performed to investigate the structural and magnetic properties of YBa2(Cu1-xFex)3O7+y with x=0.05, 0.10 (superconductors), and 0.15 (nonsuperconductor). Rietveld refinements of neutron diffraction at room temperature indicate that the Fe atoms occupy both the Cu(1) ``chain'' and Cu(2) ``plane'' sites-the occupation of the Cu(2) sites is about 30% of the total Fe content. Neutron-diffraction measurements down to 5.5 K indicate no evidence of long-range magnetic order; however, neutron small-angle scattering as a function of temperature shows a cusplike anomaly around 20 K. This suggests that the Fe-doped YBa2Cu3O7 system undergoes spin-glass ordering at low temperatures; accordingly, in the superconducting samples superconductivity and spin-glass coexist. Magnetic susceptibility for the nonsuperconducting sample gives further evidence for the spin-glass order. The results obtained are discussed in connection with the superconducting properties of this system.

  15. Pinning mechanism in electron-doped HTS Nd_{1.85}Ce_{0.15}CuO_{4-\\delta } epitaxial films

    NASA Astrophysics Data System (ADS)

    Guarino, A.; Leo, A.; Grimaldi, G.; Martucciello, N.; Dean, C.; Kunchur, M. N.; Pace, S.; Nigro, A.

    2014-12-01

    The electrical transport properties of c-axis oriented Nd1.85Ce0.15CuO4 - δ superconducting films have been investigated to analyze the pinning mechanism in this material. The samples were grown on SrTiO3 substrates using the dc sputtering high-pressure technique, whereas a detailed analysis of the structure and local composition of the films has been achieved using high-resolution electron microscopy and x-ray microanalysis. Magneto-resistance and current-voltage measurements, in the temperature range from 1.6 to 300 K and in magnetic field up to 9 T, have been reported. In particular, the anisotropic coefficient defined as the ratio between the parallel upper critical field, {{H}c2}\\parallel ab, and the perpendicular one, {{H}c2}\\parallel c, has been evaluated, pointing out the high anisotropy of this compound. Furthermore, the vortex activation energy as a function of the applied magnetic field, parallel and perpendicular to the CuO2 planes, has been derived and compared with the flux-pinning forces to enlighten the peculiar nature of pinning centers in this material.

  16. Carrier leakage into the continuum in diagonal GaAs/Al{sub 0.15}GaAs terahertz quantum cascade lasers

    SciTech Connect

    Albo, Asaf Hu, Qing

    2015-12-14

    The maximum operating temperature reported so far for THz-QCLs is ∼200 K. With the well-known degradation mechanism of thermally activated LO-phonon scattering, one straightforward strategy to improve their temperature performances is the use of diagonal structures in which the upper-to-lower state scattering time is lengthened. However, the effectiveness of this method for achieving room temperature operation remains to be demonstrated. Here, we studied the temperature degradation of highly diagonal GaAs/Al{sub 0.15}GaAs THz-QCLs. By analyzing their output power dependence on temperature, we identified the physical mechanism that limits their performance to be thermally activated leakage into the continuum, as evidenced by the large activation energy of ∼80 meV extracted from the Arrhenius plot. This observation is further supported by a careful analysis of current-voltage characteristics, especially in regions of high biases. In order to significantly improve the temperature performances of diagonal THz-QCLs, this leakage should be eliminated.

  17. Low temperature neutron diffraction study of Nd1-xSrxCrO3 (0.05≤x≤0.15)

    NASA Astrophysics Data System (ADS)

    Chakraborty, Keka R.; Mukherjee, S.; Kaushik, S. D.; Rayaprol, S.; Prajapat, C. L.; Singh, M. R.; Siruguri, V.; Tyagi, A. K.; Yusuf, S. M.

    2014-06-01

    Low temperature magnetic structure of Sr substituted NdCrO3 has been investigated using neutron diffraction in the temperature range of 2-300 K. We carried out a low temperature magnetization study in the temperature range 5-300 K. The Rietveld analysis of neutron diffraction patterns led us to conclude that the Cr moments have a Gy type of alignment of spins while the Nd moments align in a -Cz type fashion for all three samples. The weighted average Cr3+/4+ ions moments were 3.19(7), 2.77(3) and 2.57(7) μB close to its theoretical Cr3+ moment value namely 3 μB at 2 K for the x=0.05, 0.1 and 0.15 samples respectively. While the Nd3+ moments for the three samples at 2 K were 3.0(1), 2.39(8) and 2.2(2), respectively.

  18. Measurement of the Proton Spin Function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV with CLAS

    SciTech Connect

    Renee Fatemi; Alexander Skabelin; Volker Burkert; Donald Crabb; Raffaella De Vita; Sebastian Kuhn; Ralph Minehart

    2003-11-01

    Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH{sub 3} target in the CLAS detector. The polarized structure function g{sub 1}(x,Q{sup 2}) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q{sup 2} = 0.15-1.64 GeV{sup 2}. The contributions to the first moment {Gamma}{sub 1}(Q{sup 2}) = g{sub 1}(x,Q{sup 2})dx were determined up to Q{sup 2}=1.2 GeV{sup 2}. Using a parameterization for g{sub 1} in the unmeasured low x regions, the complete first moment was estimated over this Q{sup 2} region. A rapid change in {Gamma}{sub 1} is observed for Q{sup 2} < 1 GeV{sup 2}, with a sign change near Q{sup 2} = 0.3 GeV{sup 2}, indicating dominant contributions from the resonance region. At Q{sup 2}=1.2 GeV{sup 2} our data are below the pQCD evolved scaling value.

  19. Magnetic and magnetocaloric properties of La0.85(Na1-xKx)0.15MnO3 ceramics produced by reactive spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Regaieg, Y.; Sicard, L.; Monnier, J.; Koubaa, M.; Ammar-Merah, S.; Cheikhrouhou, A.

    2014-05-01

    La0.85(Na1-xKx)0.15MnO3 (0 ≤ x ≤ 1) ceramics were synthesized from the raw La(OH)3, NaOH, KOH, and MnO2 powders using Reactive Spark Plasma Sintering. All the compounds were obtained as pure, dense, and ultrafine grained pellets. The Rietveld refinement of the X-Ray powder diffraction shows that all our synthesized samples are single phase and crystallize in the distorted rhombohedral system with R-3c space group. The thermal variation of their magnetization under a magnetic applied field of 50 mT shows a paramagnetic to ferromagnetic transition at a Curie temperature very close to room temperature. The magnetic entropy change, deduced from magnetization measurements versus magnetic applied field up to 5 T at several temperatures exhibits a maximum |ΔSM|max which slightly increases with increasing K content. The relative cooling power values, inferred from the |ΔSM| vs T peak broadening, vary slightly with the potassium content, reaching, values between 316 and 289 Jkg-1, in an applied magnetic field of 5 T, when x increases from 0 to 1. Technically, these large values make the prepared materials very promising for domestic magnetic refrigeration.

  20. Fatigue of LiNi0.8Co0.15Al0.05O2 in commercial Li ion batteries

    NASA Astrophysics Data System (ADS)

    Kleiner, Karin; Dixon, Ditty; Jakes, Peter; Melke, Julia; Yavuz, Murat; Roth, Christina; Nikolowski, Kristian; Liebau, Verena; Ehrenberg, Helmut

    2015-01-01

    The degradation of LiNi0.8Co0.15Al0.05O2 (LNCAO), a cathode material in lithium-ion-batteries, was studied using in situ powder diffraction and in situ Ni K edge X-ray absorption spectroscopy (XAS). The fatigued material was taken from a 7 Ah battery which was cycled for 34 weeks under defined durability conditions. Meanwhile, a cell was stored, as reference, under controlled conditions without electrochemical treatment. The fatigued LNCAO used in this study showed a capacity loss of 26% ± 9% compared to the non-cycled material. During charge and discharge the local and the overall structure of LNCAO was investigated by X-ray near edge structure (XANES) analysis, the extended X-ray absorption fine structure (EXAFS) analysis and by using Rietveld refinement of in situ powder diffraction patterns. Both powder diffraction and XAS revealed additional, rhombohedral phases which do not change with electrochemical cycling. Moreover, a phase with the lattice parameters of fully lithiated LNCAO was still present in the fatigued material at high potentials, while it was absent in the non-fatigued reference material. The coexistence of these phases is described by domains within the LNCAO particles, in correlation with the observed fatigue.

  1. Preparation and conductivity of composite apatite La9.33Si6O26 (LSO) - Zr0.85Y0.15O1.925 (YSZ)

    NASA Astrophysics Data System (ADS)

    Noviyanti, Atiek Rostika; Irwansyah, Ferli S.; Hidayat, Sahrul; Hardian, Arie; Syarif, Dani Gustaman; Yuliyati, Yati B.; Hastiawan, Iwan

    2016-02-01

    A great challenge to reduce high operating temperature of solid oxide fuel cell (SOFC) to intermediate temperature SOFC (IT-SOFC, 500-750 °C), is the development of solid electrolyte materials with high ionic conductivity at intermediate temperature range. In response to this challenge, here we report a novel composite material La9.33Si6O26 (LSO)-Zr0.85Y0.15O1.925 (YSZ). LSO-YSZ composite synthesis was carried out by combining LSO with commercial YSZ (9:1, 8:2, 7:3) using hydrothermal method. In order to get dense pellet, all of the product were sintered at 1450 °C for 3 hours. X-ray diffraction pattern of the entire pellets show typical both of LSO and YSZ pattern which indicate that the composite was succesfully formed. The highest conductivity was detected in YSZ-7LSO (YSZ:LSO = 7: 3), i.e 1.72 × 10-4 Scm-1 at 700 °C and also has low activation energy (0.88 eV). This result suggests that the LSO-YSZ composite materials are good oxide ion conductor and potential to be used as an alternative solid electrolyte in IT-SOFC technology.

  2. Thermoelectric and magnetic properties of Ca{sub 3}Co{sub 4–x}Cu{sub x}O{sub 9+δ} with x = 0.00, 0.05, 0.07, 0.10 and 0.15

    SciTech Connect

    Bhaskar, Ankam; Lin, Z.R.; Liu, Chia-Jyi

    2013-11-15

    Graphical abstract: - Highlights: • Resistivity of all the samples exhibits nonmetallic to metallic behavior in the low temperature region. • Ca{sub 3}Co{sub 3.85}Cu{sub 0.15}O{sub 9+δ} shows the highest dimensionless figure of merit. • The observed effective magnetic moments decrease with increasing Cu content. - Abstract: Ca{sub 3}Co{sub 4–x}Cu{sub x}O{sub 9+δ} (x = 0.00, 0.05, 0.07, 0.10 and 0.15) samples were prepared by conventional solid-state synthesis and their thermoelectric properties were systematically investigated. The thermopower of all the samples was positive, indicating that the predominant carriers are holes over the entire temperature range. Ca{sub 3}Co{sub 3.85}Cu{sub 0.15}O{sub 9+δ} had the highest power factor of 2.17 μW cm{sup −1} K{sup −2} at 141 K, representing an improvement of about 64.4% compared to undoped Ca{sub 3}Co{sub 4}O{sub 9+δ}. Magnetization measurements indicated that all the samples exhibit a low-spin state of cobalt ions. The observed effective magnetic moments decreased with increasing copper content.

  3. The Multidimensional Curriculum Model (MdCM)

    ERIC Educational Resources Information Center

    Vidergor, Hava E.

    2010-01-01

    The multidimensional Curriculum Model (MdCM) helps teachers to better prepare gifted and able students for our changing world, acquiring much needed skills. It is influenced by general learning theory of constructivism, notions of preparing students for 21st century, Teaching the Future Model, and current comprehensive curriculum models for…

  4. The 150/220 cm Schmidt telescope.

    NASA Astrophysics Data System (ADS)

    Bao, Ke-Ren; Li, De-Pei; Yi, Mei-Liang; Zhu, Li-Qing; Li, Chang-Jin; Xu, Jian-Hua; Zhu, Neng-Hong; Wang, Lang-Juan; Zheng, Yi-Jin

    1990-09-01

    This paper deals with the overall design of the 150/220 cm Schmidt telescope. The optics, main structure, main mirror cell and the focus keeping device, achromatic Schmidt control cell, hydrostatic bearing of polar axis, drive, CCD auto-guider, and multi microcomputer control system are discussed in detail.

  5. Characterization of 8-cm engineering model thruster

    NASA Technical Reports Server (NTRS)

    Williamson, W. S.

    1984-01-01

    Development of 8 cm ion thruster technology which was conducted in support of the Ion Auxiliary Propulsion System (IAPS) flight contract (Contract NAS3-21055) is discussed. The work included characterization of thruster performance, stability, and control; a study of the effects of cathode aging; environmental qualification testing; and cyclic lifetesting of especially critical thruster components.

  6. Soil Depth and Tillage Effects on Glyphosate Degradation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of glyphosate-resistant crops facilitated the widespread adoption of no-tillage (NT) cropping systems. The experimental objectives were to determine glyphosate sorption, mineralization, and persistence at two depths [0- to 2- cm (A) and 2- to 10-cm (B)] in a silt loam managed under long ter...

  7. Synthesis and characterization of La0.75Ca0.15Sr0.05Ba0.05MnO3-Ni0.9Zn0.1Fe2O4 multiferroic composites

    NASA Astrophysics Data System (ADS)

    Rahaman, Md. D.; Setu, S. H.; Saha, S. K.; Akther Hossain, A. K. M.

    2015-07-01

    In the present work, we report on structural, dielectric, impedance spectroscopic studies and magnetoelectric properties of (1-x) La0.75Ca0.15Sr0.05Ba0.05MnO3 (LCSBMO)+(x) Ni0.9Zn0.1Fe2O4 (NZFO) (x=0.0, 0.1, 0.2, 0.4, 0.6, 0.8 and 1.0) composites. The composites were prepared by the solid state reaction route. The coexistence of a cubic spinel NZFO phase and a tetragonal LCSBMO phase in the composites is confirmed by the X-ray diffraction measurement. Scanning electron microscopy images reveal that NZFO particles were distributed non-uniformly with some porosity in the LCSBMO matrix. Frequency dependent dielectric constant shows usual dielectric dispersion behavior, which may be attributed to the Maxwell-Wagner type interfacial polarization. At higher frequencies (≥105 Hz), due to electronic and ionic polarizations only, the dielectric constant is independent of frequency. Complex impedance shows semicircular arc due to the domination of grain boundary resistance and electric modulus confirms the presence of hopping conduction. The AC conductivity (σAC) obeys the power law and the linearity of logω2 versus logσAC plots indicates that the conduction mechanism is due to small polaron hopping. Low frequency dispersion in permeability is due to domain wall motion and the frequency stability of permeability indicates that the arrangement of the magnetic moment in the polarization process can keep up with the external field. The maximum magnetoelectric voltage coefficient of ~40 mV Oe-1 cm-1 for x=0.8.

  8. Pressure dependence of optical transitions in In{sub 0.15}Ga{sub 0.85}N/GaN multiple quantum wells

    SciTech Connect

    Shan, W.; Ager, J.W. III, and; Walukiewicz, W.; Haller, E.E. |; McCluskey, M.D.; Johnson, N.M.; Bour, D.P.

    1998-10-01

    The effects of hydrostatic pressure on optical transitions in In{sub 0.15}Ga{sub 0.85}N/GaN multiple quantum wells (MQW{close_quote}s) have been studied. The optical transition associated with confined electron and hole states in the MQW{close_quote}s was found to shift linearly to higher energy with pressure but exhibit a significantly weaker pressure dependence compared to bulklike thick epitaxial-layer samples. Similar pressure coefficients obtained by both photomodulation and photoluminescence measurements rule out the possibility of the transition involving localized states deep in the band gap. We found that the difference in the compressibility of In{sub x}Ga{sub 1{minus}x}N and GaN induces a tensile strain in the compressively strained In{sub x}Ga{sub 1{minus}x}N well layers, partially compensating the externally applied hydrostatic pressure. This mechanical effect is primarily responsible for the smaller pressure dependence of the optical transitions in the In{sub x}Ga{sub 1{minus}x}N/GaN MQW{close_quote}s. In addition, the pressure-dependent measurements allow us to identify a spectral feature observed at an energy below the GaN band gap. We conclude that this feature is due to transitions from ionized Mg acceptor states to the conduction band in the {ital p}-type GaN cladding layer rather than a confined transition in the MQW{close_quote}s. {copyright} {ital 1998} {ital The American Physical Society}

  9. Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data

    NASA Astrophysics Data System (ADS)

    Coutens, A.; Vastel, C.; Hincelin, U.; Herbst, E.; Lis, D. C.; Chavarría, L.; Gérin, M.; van der Tak, F. F. S.; Persson, C. M.; Goldsmith, P. F.; Caux, E.

    2014-12-01

    Understanding water deuterium fractionation is important for constraining the mechanisms of water formation in interstellar clouds. Observations of HDO and H_2^{18}O transitions were carried out towards the high-mass star-forming region G34.26+0.15 with the Heterodyne Instrument for the Far-Infrared (HIFI) instrument onboard the Herschel Space Observatory, as well as with ground-based single-dish telescopes. 10 HDO lines and three H_2^{18}O lines covering a broad range of upper energy levels (22-204 K) were detected. We used a non-local thermal equilibrium 1D analysis to determine the HDO/H2O ratio as a function of radius in the envelope. Models with different water abundance distributions were considered in order to reproduce the observed line profiles. The HDO/H2O ratio is found to be lower in the hot core (˜3.5 × 10-4-7.5 × 10-4) than in the colder envelope (˜1.0 × 10-3-2.2 × 10-3). This is the first time that a radial variation of the HDO/H2O ratio has been found to occur in a high-mass source. The chemical evolution of this source was modelled as a function of its radius and the observations are relatively well reproduced. The comparison between the chemical model and the observations leads to an age of ˜105 yr after the infrared dark cloud stage.

  10. The transformation behavior of Cu-8.0Ni-1.8Si-0.6Sn-0.15Mg alloy during isothermal heat treatment

    SciTech Connect

    Lei Qian; Li Zhou Zhu Anyin; Qiu Wenting; Liang Shuquan

    2011-09-15

    The transformation behavior of Cu-8.0Ni-1.8Si-0.6Sn-0.15Mg alloy during isothermal heat treatment has been studied by transmission electron microscope observation. On the basis of micro-hardness measurement, time-temperature-property curves of the alloy have been established, and nose-temperatures of curves are about 650 deg. C. Discontinuous precipitates appeared as the samples isothermal heat treated at 550 deg. C, while continuous precipitates appeared as the samples isothermal heat treated at temperatures below 550 deg. C and above 650 deg. C. {beta}-Ni{sub 3}Si, {delta}-Ni{sub 2}Si and {delta}'-Ni{sub 2}Si precipitates were observed in the specimens. The crystal orientation relationships between copper matrix and precipitates were determined as (02-bar 2-bar){sub Cu} || (01-bar 1-bar){sub {beta}} || (010){sub {delta}}, [100]{sub Cu} || [100]{sub {beta}} || [001]{sub {delta}};(02-bar 2-bar){sub Cu} || (01-bar 1-bar){sub {beta}} || (100){sub {delta}} ', [100]{sub Cu} || [100]{sub {beta}} || [001]{sub {delta}} '. - Highlights: {yields} TTP curves have been established and their nose-tip temperatures are about 650 deg. C. {yields} Discontinuous precipitation appeared during isothermal treated at 550 deg. C. {yields} Continuous precipitation appeared when temperature is below 550 deg. C and above 650 deg. C. {yields} Crystal orientations relationships are: (02-bar 2-bar){sub Cu} || (01-bar 1-bar){sub {beta}} || (010){sub {delta}}, [100]{sub Cu} || [100]{sub {beta}} || [001]{sub {delta}};(02-bar 2-bar){sub Cu} || (01-bar 1-bar){sub {beta}} || (100){sub {delta}} ', [100]{sub Cu} || [100]{sub {beta}} || [001]{sub {delta}} '.

  11. Effect of Defects on Decay of Voltage and Capacity for Li[Li0.15Ni0.2Mn0.6]O2 Cathode Material.

    PubMed

    Yan, Wuwei; Liu, Yongning; Guo, Shengwu; Jiang, Tao

    2016-05-18

    Lithium-rich manganese metal layered oxides are very promising cathode materials for high-energy-density lithium-ion batteries, but improvement in voltage decay and capacity fade is a great challenge, which is mainly related to the structural instability or reconstruction of material's surface. Defects, such as part lattice distortions, local cation disordering and atomic ununiformity, often aggravate the further structural changes upon cycling. In this paper, we found that PEG contributed to form better layered structure, well crystallinity, uniform composition and polyhedral nanoparticles for Li[Li0.15Ni0.2Mn0.6]O2 (LNMO). On the basis of the comparative trial, a mechanism of electronegativity difference is proposed to elucidate cation nonuniform distribution. Higher electronegativity of Ni (1.91) than Mn (1.55) show a stronger ability of attraction between Ni and O atoms, and then led to Ni atoms show stronger diffusion driving force toward particle surface to contact the rich O atoms during sintering in air. However, PEG polymer can form a better barrier for more O atoms to attract Ni and Mn atoms on particle surface so that facilitated a uniform distribution. The electrochemical test indicated that the decay of discharge capacity and working voltage was mitigated, which was identified by the result of HRTEM analysis that the initial less defect structure obviously retarded the phase transformation from the layered to spinel after 50 cycles. Therefore, defects are crucial for understanding the voltage fade and capacity decay, and the improvement of performance also demonstrates that designing optimum compositions and ordering atomic arrangements will contribute to stabilize the surface structure and restrain inherent phase transitions. PMID:27116571

  12. Variable depth core sampler

    DOEpatents

    Bourgeois, Peter M.; Reger, Robert J.

    1996-01-01

    A variable depth core sampler apparatus comprising a first circular hole saw member, having longitudinal sections that collapses to form a point and capture a sample, and a second circular hole saw member residing inside said first hole saw member to support the longitudinal sections of said first hole saw member and prevent them from collapsing to form a point. The second hole saw member may be raised and lowered inside said first hole saw member.

  13. Variable depth core sampler

    DOEpatents

    Bourgeois, P.M.; Reger, R.J.

    1996-02-20

    A variable depth core sampler apparatus is described comprising a first circular hole saw member, having longitudinal sections that collapses to form a point and capture a sample, and a second circular hole saw member residing inside said first hole saw member to support the longitudinal sections of said first hole saw member and prevent them from collapsing to form a point. The second hole saw member may be raised and lowered inside said first hole saw member. 7 figs.

  14. Burn Depth Monitor

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Supra Medical Systems is successfully marketing a device that detects the depth of burn wounds in human skin. To develop the product, the companyused technology developed by NASA Langley physicists looking for better ultrasonic detection of small air bubbles and cracks in metal. The device is being marketed to burn wound analysis and treatment centers. Through a Space Act agreement, NASA and the company are also working to further develop ultrasonic instruments for new medical applications.

  15. Burn Depth Monitor

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Supra Medical Systems is successfully marketing a device that detects the depth of burn wounds in human skin. To develop the product, the company used technology developed by NASA Langley physicists looking for better ultrasonic detection of small air bubbles and cracks in metal. The device is being marketed to burn wound analysis and treatment centers. Through a Space Act agreement, NASA and the company are also working to further develop ultrasonic instruments for new medical applications

  16. Burn Depth Monitor

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Supra Medical Systems is successfully marketing a device that detects the depth of burn wounds in human skin. To develop the product, the company used technology developed by NASA Langley physicists looking for better ultrasonic detection of small air bubbles and cracks in metal. The device is being marketed to burn wound analysis and treatment centers. Through a Space Act agreement, NASA and the company are also working to further develop ultrasonic instruments for new medical applications.

  17. Hydrogen-Broadened Water from 50 to 300 cm-1 and 1300 to 4000 cm-1

    NASA Technical Reports Server (NTRS)

    Brown, L.; Peterson, D.; Plymate, C.

    1995-01-01

    To support remote sensing of the outer planets, absorption spectra of H2O broadened by H2 were recorded at room temperature using two Fourier transform spectrometers. The data from 1300 to 4000 cm-1 were obtained at 0.012 cm-1 resolution with the McMath FTS located at Kitt Peak National Observatory/National Solar Observatory. The remainder of the spectral data from 55 to 320 cm-1 were taken at 0.0056 cm-1 with the Bruker FTS.

  18. Variable depth core sampler

    SciTech Connect

    Bourgeois, P.M.; Reger, R.J.

    1994-12-31

    This invention relates to a sampling means, more particularly to a device to sample hard surfaces at varying depths. Often it is desirable to take samples of a hard surface wherein the samples are of the same diameter but of varying depths. Current practice requires that a full top-to-bottom sample of the material be taken, using a hole saw, and boring a hole from one end of the material to the other. The sample thus taken is removed from the hole saw and the middle of said sample is then subjected to further investigation. This paper describes a variable depth core sampler comprimising a circular hole saw member, having longitudinal sections that collapse to form a point and capture a sample, and a second saw member residing inside the first hole saw member to support the longitudinal sections of the first member and prevent them from collapsing to form a point. The second hole saw member may be raised and lowered inside the the first hole saw member.

  19. 15 cm multipole gas ion thruster

    NASA Technical Reports Server (NTRS)

    Isaacson, G. C.; Kaufman, H. R.

    1976-01-01

    A 15-cm multipole thruster was operated on argon and xenon. The multipole approach used has been shown capable of low discharge losses and flat ion beam profiles with a minimum of redesign. This approach employs low magnetic field strengths and flat or cylindrical sheet-metal parts, hence is suited to rapid optimization and scaling. Only refractory metal cathodes were used in this investigation.

  20. Constraining dark matter through 21-cm observations

    NASA Astrophysics Data System (ADS)

    Valdés, M.; Ferrara, A.; Mapelli, M.; Ripamonti, E.

    2007-05-01

    Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21-cm line signal. If dark matter (DM) decays or annihilates, the corresponding energy input affects the hydrogen kinetic temperature and ionized fraction, and contributes to the Lyα background. The changes induced by these processes on the 21-cm signal can then be used to constrain the proposed DM candidates, among which we select the three most popular ones: (i) 25-keV decaying sterile neutrinos, (ii) 10-MeV decaying light dark matter (LDM) and (iii) 10-MeV annihilating LDM. Although we find that the DM effects are considerably smaller than found by previous studies (due to a more physical description of the energy transfer from DM to the gas), we conclude that combined observations of the 21-cm background and of its gradient should be able to put constrains at least on LDM candidates. In fact, LDM decays (annihilations) induce differential brightness temperature variations with respect to the non-decaying/annihilating DM case up to ΔδTb = 8 (22) mK at about 50 (15) MHz. In principle, this signal could be detected both by current single-dish radio telescopes and future facilities as Low Frequency Array; however, this assumes that ionospheric, interference and foreground issues can be properly taken care of.

  1. Mapmaking for precision 21 cm cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Tegmark, Max; Liu, Adrian; Ewall-Wice, Aaron; Hewitt, Jacqueline N.; Morales, Miguel F.; Neben, Abraham R.; Parsons, Aaron R.; Zheng, Haoxuan

    2015-01-01

    In order to study the "Cosmic Dawn" and the Epoch of Reionization with 21 cm tomography, we need to statistically separate the cosmological signal from foregrounds known to be orders of magnitude brighter. Over the last few years, we have learned much about the role our telescopes play in creating a putatively foreground-free region called the "EoR window." In this work, we examine how an interferometer's effects can be taken into account in a way that allows for the rigorous estimation of 21 cm power spectra from interferometric maps while mitigating foreground contamination and thus increasing sensitivity. This requires a precise understanding of the statistical relationship between the maps we make and the underlying true sky. While some of these calculations would be computationally infeasible if performed exactly, we explore several well-controlled approximations that make mapmaking and the calculation of map statistics much faster, especially for compact and highly redundant interferometers designed specifically for 21 cm cosmology. We demonstrate the utility of these methods and the parametrized trade-offs between accuracy and speed using one such telescope, the upcoming Hydrogen Epoch of Reionization Array, as a case study.

  2. Polyhedral Serpentine Grains in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Dodony, Istvan; Stroud, Rhonda M.; Buseck, Peter R.

    2005-01-01

    CM chondrites are primitive rocks that experienced aqueous alteration in the early solar system. Their matrices and fine-grained rims (FGRs) sustained the effects of alteration, and the minerals within them hold clues to the aqueous reactions. Sheet silicates are an important product of alteration, and those of the serpentine group are abundant in the CM2 chondrites. Here we expand on our previous efforts to characterize the structure and chemistry of serpentines in CM chondrites and report results on a polyhedral form that is structurally similar to polygonal serpentine. Polygonal serpentine consists of tetrahedral (T) sheets joined to M(2+)-centered octahedral (O) sheets (where (M2+) is primarily Mg(2+) and Fe(2+)), which give rise to a 1:1 (TO) layered structure with a 0.7-nm layer periodicity. The structure is similar to chrysotile in that it consists of concentric lizardite layers wrapped around the fiber axis. However, unlike the rolled-up chrysotile, the tetrahedral sheets of the lizardite layers are periodically inverted and kinked, producing sectors. The relative angles between sectors result in 15- and 30-sided polygons in terrestrial samples.

  3. Statistical classification of vegetation and water depths in montane wetlands

    USGS Publications Warehouse

    Sharp, Julia L.; Sodja, Richard S.; Greenwood, Mark; Rosenberry, Donald O.; Warren, Jeffrey M.

    2013-01-01

    Relationships between water depths and density of submergent vegetation were studied in montane wetlands using statistical techniques based on clustering and an extension of regression trees. Sago pondweed (Stuckenia pectinata) was associated with lower average water depths than water milfoil (Myriophyllum sibiricum). We detected a nonlinear relationship when average water depths were used to predict percent cover in S. pectinata, with depths of 30–40 cm, producing the highest predicted average percent cover of S. pectinata; higher and lower depths resulted in lower percent cover predictions. For M. sibiricum, higher water depths were monotonically associated with higher average percent cover. To foster more S. pectinata and less M. sibiricum, managers might employ water control structures to reduce water depths below 1 m, using both temporary drawdowns and average depths of 30–40 cm. Other species responded less markedly to water depth variation. Should decreased water depths become more common, these results suggest an increase in S. pectinata and a decrease in M. sibiricum.

  4. ICD-10-CM/PCS: Transferring Knowledge from ICD-9-CM

    PubMed Central

    Sand, Jaime N.; Elison-Bowers, Patt

    2013-01-01

    The transition to ICD-10-CM/PCS has expanded educational opportunities for educators and trainers who are taking on the responsibility of training coders on the new system. Coding education currently faces multiple challenges in the areas of how to train the new workforce, what might be the most efficient method of providing that training, how much retraining of the current workforce with ICD-9-CM training will be required, and how to meet the national implementation deadline of 2014 in the most efficacious manner. This research sought to identify if there was a difference between a group of participants with no knowledge of ICD-9-CM and those with some knowledge of ICD-9-CM in scores on an ICD-10-CM/PCS quiz. Results indicate a difference, supporting the idea of knowledge transfer between the systems and providing additional insight into coding education. PMID:23861677

  5. Mapping Cosmic Structure Using 21-cm Hydrogen Signal at Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Voytek, Tabitha; GBT 21-cm Intensity Mapping Group

    2011-05-01

    We are using the Green Bank Telescope to make 21-cm intensity maps of cosmic structure in a 0.15 Gpc^3 box at redshift of z 1. The intensity mapping technique combines the flux from many galaxies in each pixel, allowing much greater mapping speed than the traditional redshift survey. Measurement is being made at z 1 to take advantage of a window in frequency around 700 MHz where terrestrial radio frequency interference (RFI) is currently at a minimum. This minimum is due to a reallocation of this frequency band from analog television to wide area wireless internet and public service usage. We will report progress of our attempt to detect autocorrelation of the 21-cm signal. The ultimate goal of this mapping is to use Baryon Acoustic Oscillations to provide more precise constraints to dark energy models.

  6. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  7. Isotope shifts in methane near 6000/cm

    NASA Technical Reports Server (NTRS)

    Fox, K.; Halsey, G. W.; Jennings, D. E.

    1976-01-01

    Isotope shifts for cleanly resolved vibrational-rotational absorption lines of CH4-12 and CH4-13 were measured by a 5-m focal length Littrow spectrometer in the 6000/cm range. The methane isotopes were held in separate absorption cells: 20 torr of CH4-13 in a 1-m cell, and 5 torr of CH4-12 in a White cell of 4-m optical path length. Measured shifts for the cleanly resolved singlets R(0), R(1), Q(1) and P(1) are summarized in tabular form.

  8. An engineering model 30 cm ion thruster

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; King, H. J.; Schnelker, D. E.

    1973-01-01

    Thruster development at Hughes Research Laboratories and NASA Lewis Research Center has brought the 30-cm mercury bombardment ion thruster to the state of an engineering model. This thruster has been designed to have sufficient internal strength for direct mounting on gimbals, to weigh 7.3 kg, to operate with a corrected overall efficiency of 71%, and to have 10,000 hours lifetime. Subassemblies, such as the ion optical system, isolators, etc., have been upgraded to meet launch qualification standards. This paper presents a summary of the design specifications and performance characteristics which define the interface between the thruster module and the remainder of the propulsion system.

  9. Probing patchy reionization through τ-21 cm correlation statistics

    SciTech Connect

    Meerburg, P. Daniel; Spergel, David N.; Dvorkin, Cora E-mail: dns@astro.princeton.edu

    2013-12-20

    We consider the cross-correlation between free electrons and neutral hydrogen during the epoch of reionization (EoR). The free electrons are traced by the optical depth to reionization τ, while the neutral hydrogen can be observed through 21 cm photon emission. As expected, this correlation is sensitive to the detailed physics of reionization. Foremost, if reionization occurs through the merger of relatively large halos hosting an ionizing source, the free electrons and neutral hydrogen are anticorrelated for most of the reionization history. A positive contribution to the correlation can occur when the halos that can form an ionizing source are small. A measurement of this sign change in the cross-correlation could help disentangle the bias and the ionization history. We estimate the signal-to-noise ratio of the cross-correlation using the estimator for inhomogeneous reionization τ-hat {sub ℓm} proposed by Dvorkin and Smith. We find that with upcoming radio interferometers and cosmic microwave background (CMB) experiments, the cross-correlation is measurable going up to multipoles ℓ ∼ 1000. We also derive parameter constraints and conclude that, despite the foregrounds, the cross-correlation provides a complementary measurement of the EoR parameters to the 21 cm and CMB polarization autocorrelations expected to be observed in the coming decade.

  10. Fuel elements of research reactor CM

    SciTech Connect

    Kozlov, A.V.; Morozov, A.V.; Vatulin, A.V.; Ershov, S.A.

    2013-07-01

    In 1961 the CM research reactor was commissioned at the Research Institute of Atomic Reactors (Dimitrovgrad, Russia), it was intended to carry on investigations and the production of transuranium nuclides. The reactor is of a tank type. Original fuel assembly contained plate fuels that were spaced with vanes and corrugated bands. Nickel was used as a cladding material, fuel meat was produced from UO{sub 2} + electrolytic nickel composition. Fuel plates have been replaced by self-spacing cross-shaped dispersion fuels clad in stainless steel. In 2005 the reactor was updated. The purpose of this updating was to increase the quantity of irradiation channels in the reactor core and to improve the neutron balance. The updating was implemented at the expense of 20 % reduction in the quantity of fuel elements in the core which released a space for extra channels and decreased the mass of structural materials in the core. The updated reactor is loaded with modified standard fuel elements with 20 % higher uranium masses. At the same time stainless steel in fuel assembly shrouds was substituted by zirconium alloy. Today in progress are investigations and work to promote the second stage of reactor updating that involve developments of cross-shaped fuel elements having low neutron absorption matrix materials. This article gives an historical account of the design and main technical changes that occurred for the CM reactor since its commissioning.

  11. Redundant Array Configurations for 21 cm Cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Parsons, Aaron R.

    2016-08-01

    Realizing the potential of 21 cm tomography to statistically probe the intergalactic medium before and during the Epoch of Reionization requires large telescopes and precise control of systematics. Next-generation telescopes are now being designed and built to meet these challenges, drawing lessons from first-generation experiments that showed the benefits of densely packed, highly redundant arrays—in which the same mode on the sky is sampled by many antenna pairs—for achieving high sensitivity, precise calibration, and robust foreground mitigation. In this work, we focus on the Hydrogen Epoch of Reionization Array (HERA) as an interferometer with a dense, redundant core designed following these lessons to be optimized for 21 cm cosmology. We show how modestly supplementing or modifying a compact design like HERA’s can still deliver high sensitivity while enhancing strategies for calibration and foreground mitigation. In particular, we compare the imaging capability of several array configurations, both instantaneously (to address instrumental and ionospheric effects) and with rotation synthesis (for foreground removal). We also examine the effects that configuration has on calibratability using instantaneous redundancy. We find that improved imaging with sub-aperture sampling via “off-grid” antennas and increased angular resolution via far-flung “outrigger” antennas is possible with a redundantly calibratable array configuration.

  12. 30-cm electron cyclotron plasma generator

    NASA Technical Reports Server (NTRS)

    Goede, Hank

    1987-01-01

    Experimental results on the development of a 30-cm-diam electron cyclotron resonance plasma generator are presented. This plasma source utilizes samarium-cobalt magnets and microwave power at a frequency of 4.9 GHz to produce a uniform plasma with densities of up to 3 x 10 to the 11th/cu cm in a continuous fashion. The plasma generator contains no internal structures, and is thus inherently simple in construction and operation and inherently durable. The generator was operated with two different magnetic geometries. One used the rare-earth magnets arranged in an axial line cusp configuration, which directly showed plasma production taking place near the walls of the generator where the electron temperature was highest but with the plasma density peaking in the central low B-field regions. The second configuration had magnets arranged to form azimuthal line cusps with approximately closed electron drift surfaces; this configuration showed an improved electrical efficiency of about 135 eV/ion.

  13. Combining galaxy and 21-cm surveys

    NASA Astrophysics Data System (ADS)

    Cohn, J. D.; White, Martin; Chang, Tzu-Ching; Holder, Gil; Padmanabhan, Nikhil; Doré, Olivier

    2016-04-01

    Acoustic waves travelling through the early Universe imprint a characteristic scale in the clustering of galaxies, QSOs and intergalactic gas. This scale can be used as a standard ruler to map the expansion history of the Universe, a technique known as baryon acoustic oscillations (BAO). BAO offer a high-precision, low-systematics means of constraining our cosmological model. The statistical power of BAO measurements can be improved if the `smearing' of the acoustic feature by non-linear structure formation is undone in a process known as reconstruction. In this paper, we use low-order Lagrangian perturbation theory to study the ability of 21-cm experiments to perform reconstruction and how augmenting these surveys with galaxy redshift surveys at relatively low number densities can improve performance. We find that the critical number density which must be achieved in order to benefit 21-cm surveys is set by the linear theory power spectrum near its peak, and corresponds to densities achievable by upcoming surveys of emission line galaxies such as eBOSS and DESI. As part of this work, we analyse reconstruction within the framework of Lagrangian perturbation theory with local Lagrangian bias, redshift-space distortions, {k}-dependent noise and anisotropic filtering schemes.

  14. THE METALLICITY OF THE CM DRACONIS SYSTEM

    SciTech Connect

    Terrien, Ryan C.; Fleming, Scott W.; Mahadevan, Suvrath; Deshpande, Rohit; Bender, Chad F.; Ramsey, Lawrence W.; Feiden, Gregory A.

    2012-11-20

    The CM Draconis system comprises two eclipsing mid-M dwarfs of nearly equal mass in a 1.27 day orbit. This well-studied eclipsing binary has often been used for benchmark tests of stellar models, since its components are among the lowest mass stars with well-measured masses and radii ({approx}< 1% relative precision). However, as with many other low-mass stars, non-magnetic models have been unable to match the observed radii and effective temperatures for CM Dra at the 5%-10% level. To date, the uncertain metallicity of the system has complicated comparison of theoretical isochrones with observations. In this Letter, we use data from the SpeX instrument on the NASA Infrared Telescope Facility to measure the metallicity of the system during primary and secondary eclipses, as well as out of eclipse, based on an empirical metallicity calibration in the H and K near-infrared (NIR) bands. We derive an [Fe/H] = -0.30 {+-} 0.12 that is consistent across all orbital phases. The determination of [Fe/H] for this system constrains a key dimension of parameter space when attempting to reconcile model isochrone predictions and observations.

  15. Fission probabilities of 242Am,243Cm , and 244Cm induced by transfer reactions

    NASA Astrophysics Data System (ADS)

    Kessedjian, G.; Jurado, B.; Barreau, G.; Marini, P.; Mathieu, L.; Tsekhanovich, I.; Aiche, M.; Boutoux, G.; Czajkowski, S.; Ducasse, Q.

    2015-04-01

    We have measured the fission probabilities of 242Am,243Cm , and 244Cm induced by the transfer reactions 243Am(3He,4He) ,243Am(3He,t ) , and 243Am(3He,d ) , respectively. The details of the experimental procedure and a rigorous uncertainty analysis, including a correlation matrix, are presented. For 243Cm our data show clear structures well below the fission threshold. To our knowledge, it is the first time that these structures have been observed for this nucleus. We have compared the measured fission probabilities to calculations based on the statistical model to obtain information on the fission barriers of the produced fissioning nuclei.

  16. Aliphatic amines in Antarctic CR2, CM2, and CM1/2 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Aponte, José C.; McLain, Hannah L.; Dworkin, Jason P.; Elsila, Jamie E.

    2016-09-01

    Meteoritic water-soluble organic compounds provide a unique record of the processes that occurred during the formation of the solar system and the chemistry preceding the origins of life on Earth. We have investigated the molecular distribution, compound-specific δ13C isotopic ratios and enantiomeric compositions of aliphatic monoamines present in the hot acid-water extracts of the carbonaceous chondrites LAP 02342 (CR2), GRA 95229 (CR2), LON 94101 (CM2), LEW 90500 (CM2), and ALH 83100 (CM1/2). Analyses of the concentration of monoamines in these meteorites revealed: (a) the CR2 chondrites studied here contain higher concentrations of monoamines relative to the analyzed CM2 chondrites; (b) the concentration of monoamines decreases with increasing carbon number; and (c) isopropylamine is the most abundant monoamine in these CR2 chondrites, while methylamine is the most abundant amine species in these CM2 and CM1/2 chondrites. The δ13C values of monoamines in CR2 chondrite do not correlate with the number of carbon atoms; however, in CM2 and CM1/2 chondrites, the 13C enrichment decreases with increasing monoamine carbon number. The δ13C values of methylamine in CR2 chondrites ranged from -1 to +10‰, while in CM2 and CM1/2 chondrites the δ13C values of methylamine ranged from +41 to +59‰. We also observed racemic compositions of sec-butylamine, 3-methyl-2-butylamine, and sec-pentylamine in the studied carbonaceous chondrites. Additionally, we compared the abundance and δ13C isotopic composition of monoamines to those of their structurally related amino acids. We found that monoamines are less abundant than amino acids in CR2 chondrites, with the opposite being true in CM2 and CM1/2 chondrites. We used these collective data to evaluate different primordial synthetic pathways for monoamines in carbonaceous chondrites and to understand the potential common origins these molecules may share with meteoritic amino acids.

  17. Rainfall exclusion in an eastern Amazonian forest alters soil water movement and depth of water uptake.

    PubMed

    Romero-Saltos, Hugo; Sternberg, Leonel da S L; Moreira, Marcelo Z; Nepstad, Daniel C

    2005-03-01

    Deuterium-labeled water was used to study the effect of the Tapajós Throughfall Exclusion Experiment (TTEE) on soil moisture movement and on depth of water uptake by trees of Coussarea racemosa, Sclerolobium chrysophyllum, and Eschweilera pedicellata. The TTEE simulates an extended dry season in an eastern Amazonian rainforest, a plausible scenario if the El Niño phenomenon changes with climate change. The TTEE excludes 60% of the wet season throughfall from a 1-ha plot (treatment), while the control 1-ha plot receives precipitation year-round. Mean percolation rate of the label peak in the control plot was greater than in the treatment plot during the wet season (0.75 vs. 0.07 m/mo). The rate was similar for both plots during the dry season (ca. 0.15 m/mo), indicative that both plots have similar topsoil structure. Interestingly, the label peak in the control plot during the dry season migrated upward an average distance of 64 cm. We show that water probably moved upward through soil pores-i.e., it did not involve roots (hydraulic lift)-most likely because of a favorable gradient of total (matric + gravitational) potential coupled with sufficient unsaturated hydraulic conductivity. Water probably also moved upward in the treatment plot, but was not detectable; the label in this plot did not percolate below 1 m or beyond the depth of plant water uptake. During the dry season, trees in the rainfall exclusion plot, regardless of species, consistently absorbed water significantly deeper, but never below 1.5-2 m, than trees in the control plot, and therefore may represent expected root function of this understory/subcanopy tree community during extended dry periods. PMID:21652421

  18. Overcoming the Challenges of 21cm Cosmology

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan

    The highly-redshifted 21cm line of neutral hydrogen is one of the most promising and unique probes of cosmology for the next decade and beyond. The past few years have seen a number of dedicated experiments targeting the 21cm signal from the Epoch of Reionization (EoR) begin operation, including the LOw-Frequency ARray (LOFAR), the Murchison Widefield Array (MWA), and the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER). For these experiments to yield cosmological results, they require new calibration and analysis algorithms which will need to achieve unprecedented levels of separation between the 21cm signal and contaminating foreground emission. Although much work has been spent developing these algorithms over the past decade, their success or failure will ultimately depend on their ability to overcome the complications associated with real-world systems and their inherent complications. The work in this dissertation is closely tied to the late-stage commissioning and early observations with PAPER. The first two chapters focus on developing calibration algorithms to overcome unique problems arising in the PAPER system. To test these algorithms, I rely on not only simulations, but on commissioning observations, ultimately tying the success of the algorithm to its performance on actual, celestial data. The first algorithm works to correct gain-drifts in the PAPER system caused by the heating and cooling of various components (the amplifiers and above ground co-axial cables, in particular). It is shown that a simple measurement of the ambient temperature can remove ˜ 10% gain fluctuations in the observed brightness of calibrator sources. This result is highly encouraging for the ability of PAPER to remove a potentially dominant systematic in its power spectrum and cataloging measurements without resorting to a complicated system overhaul. The second new algorithm developed in this dissertation solves a major calibration challenge not

  19. Designing new biocompatible glass-forming Ti75-x Zr10 Nbx Si15 (x = 0, 15) alloys: corrosion, passivity, and apatite formation.

    PubMed

    Abdi, Somayeh; Oswald, Steffen; Gostin, Petre Flaviu; Helth, Arne; Sort, Jordi; Baró, Maria Dolors; Calin, Mariana; Schultz, Ludwig; Eckert, Jürgen; Gebert, Annett

    2016-01-01

    Glass-forming Ti-based alloys are considered as potential new materials for implant applications. Ti75 Zr10 Si15 and Ti60 Zr10 Nb15 Si15 alloys (free of cytotoxic elements) can be produced as melt-spun ribbons with glassy matrix and embedded single β-type nanocrystals. The corrosion and passivation behavior of these alloys in their homogenized melt-spun states have been investigated in Ringer solution at 37°C in comparison to their cast multiphase crystalline counterparts and to cp-Ti and β-type Ti-40Nb. All tested materials showed very low corrosion rates as expressed in corrosion current densities icorr  < 50 nA/cm(2). Electrochemical and surface analytical studies revealed a high stability of the new alloys passive states in a wide potential range. This corresponds to low passive current densities ipass  = 2 ± 1 µA/cm(2) based on the growth of oxide films with thickness d <10 nm. A homogeneous constituent distribution in the melt-spun alloys is beneficial for stable surface passivity. The addition of Nb does not only improve the glass-forming ability and the mechanical properties but also supports a high pitting resistance even at extreme anodic polarization up to 4V versus SCE were oxide thickness values of d ∼35 nm are reached. With regard to the corrosion properties, the Nb-containing nearly single-phase glassy alloy can compete with the β-type Ti-40Nb alloy. SBF tests confirmed the ability for formation of hydroxyapatite on the melt-spun alloy surfaces. All these properties recommend the new glass-forming alloys for application as wear- and corrosion-resistant coating materials for implants. PMID:25611821

  20. The 30-cm ion thruster power processor

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hopper, D. J.

    1978-01-01

    A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range.

  1. 70-cm radar observations of 433 Eros

    NASA Technical Reports Server (NTRS)

    Campbell, D. B.; Pettengill, G. H.; Shapiro, I. I.

    1976-01-01

    Radar observations of 433 Eros were made at the Arecibo Observatory using a wavelength of 70 cm during the close approach of Eros to earth in mid-January, 1975. A peak radar cross section of plus or minus 15 sq km was observed. The spectral broadening obtained was approximately 30 Hz, which is consistent with a value of 16 km for the maximum radius of the asteroid. The surface of Eros appears to be relatively rough at the scale of a wavelength as compared to the surfaces of the terrestrial planets and the moon. The composition of the surface is not well determined, except that it cannot be a highly conducting metal. A single measurement each of round-trip echo times delay and Doppler shift was made.

  2. NASA 30 Cm Ion Thruster Development Status

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Haag, Thomas W.; Rawlin, Vincent K.; Kussmaul, Michael T.

    1995-01-01

    A 30 cm diameter xenon ion thruster is under development at NASA to provide an ion propulsion option for missions of national interest and it is an element of the NASA Solar Electric Propulsion Technology Applications Readiness (NSTAR) program established to validate ion propulsion for space flight applications. The thruster has been developed to an engineering model level and it incorporates innovations in design, materials, and fabrication techniques compared to those employed to conventional ion thrusters. The performance of both functional and engineering model thrusters has been assessed including thrust stand measurements, over an input power range of 0.5-2.3 kW. Attributes of the engineering model thruster include an overall mass of 6.4 kg, and an efficiency of 65 percent and thrust of 93 mN at 2.3 kW input power. This paper discusses the design, performance, and lifetime expectations of the functional and engineering model thrusters under development at NASA.

  3. Evaluation of Argonne 9-cm and 10-cm Annular Centrifugal Contactors for SHINE Solution Processing

    SciTech Connect

    Wardle, Kent E.; Pereira, Candido; Vandegrift, George

    2015-02-01

    Work is in progress to evaluate the SHINE Medical Technologies process for producing Mo-99 for medical use from the fission of dissolved low-enriched uranium (LEU). This report addresses the use of Argonne annular centrifugal contactors for periodic treatment of the process solution. In a letter report from FY 2013, Pereira and Vandegrift compared the throughput and physical footprint for the two contactor options available from CINC Industries: the V-02 and V-05, which have rotor diameters of 5 cm and 12.7 cm, respectively. They suggested that an intermediately sized “Goldilocks” contactor might provide a better balance between throughput and footprint to meet the processing needs for the uranium extraction (UREX) processing of the SHINE solution to remove undesired fission products. Included with the submission of this letter report are the assembly drawings for two Argonne-design contactors that are in this intermediate range—9-cm and 10-cm rotors, respectively. The 9-cm contactor (drawing number CE-D6973A, stamped February 15, 1978) was designed as a single-stage unit and built and tested in the late 1970s along with other size units, both smaller and larger. In subsequent years, a significant effort to developed annular centrifugal contactors was undertaken to support work at Hanford implementing the transuranic extraction (TRUEX) process. These contactors had a 10-cm rotor diameter and were fully designed as multistage units with four stages per assembly (drawing number CMT-E1104, stamped March 14, 1990). From a technology readiness perspective, these 10-cm units are much farther ahead in the design progression and, therefore, would require significantly less re-working to make them ready for UREX deployment. Additionally, the overall maximum throughput of ~12 L/min is similar to that of the 9-cm unit (10 L/min), and the former could be efficiently operated over much of the same range of throughput. As a result, only the 10-cm units are considered here

  4. Depth inpainting by tensor voting.

    PubMed

    Kulkarni, Mandar; Rajagopalan, Ambasamudram N

    2013-06-01

    Depth maps captured by range scanning devices or by using optical cameras often suffer from missing regions due to occlusions, reflectivity, limited scanning area, sensor imperfections, etc. In this paper, we propose a fast and reliable algorithm for depth map inpainting using the tensor voting (TV) framework. For less complex missing regions, local edge and depth information is utilized for synthesizing missing values. The depth variations are modeled by local planes using 3D TV, and missing values are estimated using plane equations. For large and complex missing regions, we collect and evaluate depth estimates from self-similar (training) datasets. We align the depth maps of the training set with the target (defective) depth map and evaluate the goodness of depth estimates among candidate values using 3D TV. We demonstrate the effectiveness of the proposed approaches on real as well as synthetic data. PMID:24323102

  5. Depth dependence of electron backscatter: an energy spectral and dosimetry study using Monte Carlo simulation.

    PubMed

    Chow, James C L; Owrangi, Amir M

    2009-02-01

    This study investigated the depth dependence of electron backscatter from a layer of lead (Pb) for clinical electron beams. The change in the electron backscatter with variation in the water depth above the Pb was determined. Electron energy spectra and relative depth doses as a function of depth in water over the Pb layer were calculated using a Monte Carlo simulation and studied. Phase-space files for 4 and 9 MeV electron beams (10 x 10 cm2 applicator and cutout) based on the Varian 21 EX linear accelerator were generated using the EGSnrc-based BEAMNRC code. 3 mm of Pb, at depths of 0.5 and 1 cm in water, was irradiated with electrons. The source-to-surface distance is equal to 100 cm. Electron energy spectra and relative depth doses with and without the presence of the Pb layer at different depths in water were determined using the BEAMNRC code. For the 4 MeV electron energy spectra at a depth of 0.5 cm in water, electron backscatter was found to originate at the Pb-water interface and extend to 0.5 cm above the Pb insert. However, at a depth of 1 cm in water, electron backscatter almost disappeared at 0.5 and 1 cm above th ePb insert. This is due to the increased attenuation of the incident 4 MeV electron beam in a thicker layer of water as well as increased attenuation of the electron backscatter above the Pb. This resulted in a 23% decrease in relative dose at a measurement point of 0.5 cm depth, when the depth of the Pb insert was changed from 1 to 0.5 cm. For the electron energy spectra of the 9 MeV beams with a 0.5 cm depth of water, only a small amount of electron backscatter was observed. However, more electron backscatter was found when the water depth was increased to 1 cm. This is because the electron beam energy was decreased more due to the increase in attenuation from the increased depth of water compared to 0.5 cm. Since the electron energy spectrum and relative depth dose above the Pb layer vary with depth of water on top of the Pb, the electron

  6. Engineering model 8-cm thruster subsystem

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hyman, J.; Hopper, D. J.; Williamson, W. S.; Dulgeroff, C. R.; Collett, C. R.

    1978-01-01

    An Engineering Model (EM) 8 cm Ion Thruster Propulsion Subsystem was developed for operation at a thrust level 5 mN (1.1 mlb) at a specific impulse 1 sub sp = 2667 sec with a total system input power P sub in = 165 W. The system dry mass is 15 kg with a mercury-propellant-reservoir capacity of 8.75 kg permitting uninterrupted operation for about 12,500 hr. The subsystem can be started from a dormant condition in a time less than or equal to 15 min. The thruster has a design lifetime of 20,000 hr with 10,000 startup cycles. A gimbal unit is included to provide a thrust vector deflection capability of + or - 10 degrees in any direction from the zero position. The EM subsystem development program included thruster optimization, power-supply circuit optimization and flight packaging, subsystem integration, and subsystem acceptance testing including a cyclic test of the total propulsion package.

  7. The 15 cm diameter ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1974-01-01

    The startup reliability of a 15 cm diameter mercury bombardment ion thruster which employs a pulsed high voltage tickler electrode on the main and neutralizer cathodes is examined. Startup of the thruster is achieved 100% of the time on the main cathode and 98.7% of the time on the neutralizer cathode over a 3640 cycle test. The thruster was started from a 20 C initial condition and operated for an hour at a 600 mA beam current. An energy efficiency of 75% and a propellant utilization efficiency of 77% was achieved over the complete cycle. The effect of a single cusp magnetic field thruster length on its performance is discussed. Guidelines are formulated for the shaping of magnetic field lines in thrusters. A model describing double ion production in mercury discharges is presented. The production route is shown to occur through the single ionic ground state. Photographs of the interior of an operating-hollow cathode are presented. A cathode spot is shown to be present if the cathode is free of low work-function surfaces. The spot is observed if a low work-function oxide coating is applied to the cathode insert. Results show that low work-function oxide coatings tend to migrate during thruster operation.

  8. Fast neutron background measurements at shallow depths

    SciTech Connect

    Chen, M.; Hertenberger, R.; Novikov, V.; Dougherty, B.

    1993-10-01

    We report on measurements of the neutron backgrounds for neutrino experiments at shallow depth (such as the proposed San Onofre neutrino oscillation experiment). A detector capable of pulse-shape discrimination measured the flux of fast neutrons at 20 mwe depth in the Stanford Underground Facility to be (1.07 {+-} 0.30) X 10{sup -6} cm{sup -2} s{sup -1}. An experiment, situated in the Tendon Gallery of the San Onofre Unit 2 reactor. studied spallation neutrons from muons traversing Pb and Cu. An underground experiment in the SUF, employing a detector filled with Gd-loaded liquid scintillator, is measuring the neutron production rate and multiplicity for muon spallation in low-A material (hydrocarbon-based liquid scintillator).

  9. Deposition rate and substrate temperature effects on the structure and properties of bulk-sputtered OFHC Cu and Cu-0.15Zr. [Oxygen-Free High-Conductivity

    NASA Technical Reports Server (NTRS)

    Hecht, R. J.; Mullaly, J. R.

    1975-01-01

    Bulk-sputtered OFHC Cu and Cu-0.15 Zr used as inner walls of advanced regeneratively cooled thrust chambers are evaluated as to microstructure, surface topography, and fractography. It is found that under conditions of low substrate temperature, crystallite size and openness of the structure increase with increasing deposition rate for both materials. At elevated temperatures, an equiaxed ductile structure of OFHC Cu is produced only at low deposition rates; at higher deposition rate, open structures are observed with recrystallized equiaxed grains within large poorly bonded crystallites. The Cu-0.15 Zr alloy sputtered from the hollow cathode using a diode discharge shows open-type structures for all conditions evaluated. The use of a triode discharge in generating a dense non-voided structure of Cu-0.15 Zr is discussed.

  10. Airborne Surveys of Snow Depth over Arctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Panzer, B.; Leuschen, C.; Pang, S.; Markus, T.; Holt, B.; Gogineni, S.

    2011-01-01

    During the spring of 2009, an ultrawideband microwave radar was deployed as part of Operation IceBridge to provide the first cross-basin surveys of snow thickness over Arctic sea ice. In this paper, we analyze data from three approx 2000 km transects to examine detection issues, the limitations of the current instrument, and the regional variability of the retrieved snow depth. Snow depth is the vertical distance between the air \\snow and snow-ice interfaces detected in the radar echograms. Under ideal conditions, the per echogram uncertainty in snow depth retrieval is approx 4 - 5 cm. The finite range resolution of the radar (approx 5 cm) and the relative amplitude of backscatter from the two interfaces limit the direct retrieval of snow depths much below approx 8 cm. Well-defined interfaces are observed over only relatively smooth surfaces within the radar footprint of approx 6.5 m. Sampling is thus restricted to undeformed, level ice. In early April, mean snow depths are 28.5 +/- 16.6 cm and 41.0 +/- 22.2 cm over first-year and multiyear sea ice (MYI), respectively. Regionally, snow thickness is thinner and quite uniform over the large expanse of seasonal ice in the Beaufort Sea, and gets progressively thicker toward the MYI cover north of Ellesmere Island, Greenland, and the Fram Strait. Snow depth over MYI is comparable to that reported in the climatology by Warren et al. Ongoing improvements to the radar system and the utility of these snow depth measurements are discussed.

  11. Development of neutron depth profiling at CMRR

    NASA Astrophysics Data System (ADS)

    Li, Run-dong; Yang, Xin; Wang, Guan-bo; Dou, Hai-feng; Qian, Da-zhi; Wang, Shu-yu

    2015-07-01

    A neutron depth profiling (NDP) system has been developed at China Mianyang Research Reactor (CMRR) at Institute of Nuclear Physics and Chemistry (INPC), CAEP. The INPC-NDP system utilizes cold neutrons which are transported along the C1 neutron guide from the cold neutron source. It consists of a beam entrance, a target chamber, a beam stopper, and data acquisition electronics for charged particle pulse-height analysis. A 90 cm in diameter stainless steel target chamber was designed to control the positions of the sample and detector. The neutron beam intensity of 2.1×108 n cm-2 s-1 was calibrated by the Au foil activation method at the sample position. The INPC-NDP system was tested by using a Standard Reference Materials SRM-2137. The measured results agreed well with the reference values.

  12. Going the distance: validation of Acuros and AAA at an extended SSD of 400 cm.

    PubMed

    Lamichhane, Narottam; Patel, Vivek N; Studenski, Matthew T

    2016-01-01

    Accurate dose calculation and treatment delivery is essential for total body irradia-tion (TBI). In an effort to verify the accuracy of TBI dose calculation at our institu-tion, we evaluated both the Varian Eclipse AAA and Acuros algorithms to predict dose distributions at an extended source-to-surface distance (SSD) of 400 cm. Measurements were compared to calculated values for a 6 MV beam in physical and virtual phantoms at 400 cm SSD using open beams for both 5 × 5 and 40 × 40cm2 field sizes. Inline and crossline profiles were acquired at equivalent depths of 5 cm, 10 cm, and 20 cm. Depth-dose curves were acquired using EBT2 film and an ion chamber for both field sizes. Finally, a RANDO phantom was used to simulate an actual TBI treatment. At this extended SSD, care must be taken using the planning system as there is good relative agreement between measured and calculated profiles for both algorithms, but there are deviations in terms of the absolute dose. Acuros has better agreement than AAA in the penumbra region. PMID:27074473

  13. A sub-cm micromachined electron microscope

    NASA Technical Reports Server (NTRS)

    Feinerman, A. D.; Crewe, D. A.; Perng, D. C.; Shoaf, S. E.; Crewe, A. V.

    1993-01-01

    A new approach for fabricating macroscopic (approximately 10x10x10 mm(exp 3)) structures with micron accuracy has been developed. This approach combines the precision of semiconductor processing and fiber optic technologies. A (100) silicon wafer is anisotropically etched to create four orthogonal v-grooves and an aperture on each 10x12 mm die. Precision 308 micron optical fibers are sandwiched between the die to align the v-grooves. The fiber is then anodically bonded to the die above and below it. This procedure is repeated to create thick structures and a stack of 5 or 6 die will be used to create a miniature scanning electron microscope (MSEM). Two die in the structure will have a segmented electrode to deflect the beam and correct for astigmatism. The entire structure is UHV compatible. The performance of an SEM improves as its length is reduced and a sub-cm 2 keV MSEM with a field emission source should have approximately 1 nm resolution. A low voltage high resolution MSEM would be useful for the examination of biological specimens and semiconductors with a minimum of damage. The first MSEM will be tested with existing 6 micron thermionic sources. In the future a micromachined field emission source will be used. The stacking technology presented in this paper can produce an array of MSEMs 1 to 30 mm in length with a 1 mm or larger period. A key question being addressed by this research is the optimum size for a low voltage MSEM which will be determined by the required spatial resolution, field of view, and working distance.

  14. Tillage depth effects on soil physical properties, sugarbeet yield and quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tillage depth influences the soil-water-plant ecosystem, thereby affecting crop yield and quality. The effects of tillage depth on soil physical properties and sugarbeet (Beta vulgaris L.) yield and quality were evaluated. A field study comprised of two tillage depths: shallow (ST) of 10-cm and deep...

  15. Depth distribution of preferential flow patterns in a sandy loam soil as affected by tillage

    NASA Astrophysics Data System (ADS)

    Petersen, C. T.; Hansen, S.; Jensen, H. E.

    Dye-tracer studies using the anionic dye Brilliant Blue FCF were conducted on a structured sandy loam soil (Typic Agrudalf). 25 mm of dye solution was applied to the surface of 11 1.6 x 1.6 m field plots, some of which had been subjected to conventional seed bed preparation (harrowing) while others had been rotovated to either 5 or 15 cm depth before sowing. The soil was excavated to about 160 cm depth one or two days after dye application. Flow patterns and structural features appearing on vertical or horizontal cross sections were examined and photographed. The flow patterns were digitized, and depth functions for the number of activated flow pathways and the degree of dye coverage were calculated. Dye was found below 100 cm depth on 26 out of 33 vertical cross sections made in conventionally tilled plots showing that preferential flow was a prevailing phenomenon. The depth-averaged number of stained flow pathways in the 25-100 cm layer was significantly smaller in a plot rotovated to 5 cm depth than in a conventionally tilled plot, both under relatively dry initial soil conditions and when the entire soil profiles were initially at field capacity. There were no examples of dye penetration below 25 cm depth one month after deep rotovation. Distinct horizontal structures in flow patterns appearing at 20-40 cm depth coupled with changes in flow domains indicated soil layering with abrupt changes in soil structure and hydraulic properties.

  16. A depth dependence determination of the wedge transmission factor for 4-10 MV photon beams.

    PubMed

    McCullough, E C; Gortney, J; Blackwell, C R

    1988-01-01

    The depth dependence (up to 25 cm) of the in-phantom wedge transmission factor (WTF) has been determined for three medical linear accelerator x-ray beams with energies of 4, 6, and 10 MV containing 15 degrees-60 degrees (nominal) brass wedges. All measurements were made with a cylindrical ionization chamber in water, for a field size of 10 X 10 cm2 with a source-skin distance of 80 or 100 cm. We conclude that, for the accelerators studied, the WTF factor at depth is less than 2% different from that determined at dmax (for the nominal wedge angles and photon energies studied) unless the depth of interest is greater than 10 cm. Up to the maximum depth studied (25 cm) the relative wedge factor--that is, wedge factor at depth compared to that determined at dmax--was about equal to or less than 1.02 for the 15 degrees and 30 degrees wedges and any of the photon beam energies studied. For the seldom utilized combination of a nominal wedge angle in excess of 45 degrees with a depth greater than 10 cm, the WTF at depth can differ from the WTF determined at dmax, by up to 5%. Since the wedge transmission factor is reflective of relative percent dose data, our results also indicate that it is in error to use open field percent depth doses for certain combinations of wedge angle, photon energy, and depth. PMID:3211057

  17. Jupiter Clouds in Depth

    NASA Technical Reports Server (NTRS)

    2000-01-01

    [figure removed for brevity, see original site] 619 nm [figure removed for brevity, see original site] 727 nm [figure removed for brevity, see original site] 890 nm

    Images from NASA's Cassini spacecraft using three different filters reveal cloud structures and movements at different depths in the atmosphere around Jupiter's south pole.

    Cassini's cameras come equipped with filters that sample three wavelengths where methane gas absorbs light. These are in the red at 619 nanometer (nm) wavelength and in the near-infrared at 727 nm and 890 nm. Absorption in the 619 nm filter is weak. It is stronger in the 727 nm band and very strong in the 890 nm band where 90 percent of the light is absorbed by methane gas. Light in the weakest band can penetrate the deepest into Jupiter's atmosphere. It is sensitive to the amount of cloud and haze down to the pressure of the water cloud, which lies at a depth where pressure is about 6 times the atmospheric pressure at sea level on the Earth). Light in the strongest methane band is absorbed at high altitude and is sensitive only to the ammonia cloud level and higher (pressures less than about one-half of Earth's atmospheric pressure) and the middle methane band is sensitive to the ammonia and ammonium hydrosulfide cloud layers as deep as two times Earth's atmospheric pressure.

    The images shown here demonstrate the power of these filters in studies of cloud stratigraphy. The images cover latitudes from about 15 degrees north at the top down to the southern polar region at the bottom. The left and middle images are ratios, the image in the methane filter divided by the image at a nearby wavelength outside the methane band. Using ratios emphasizes where contrast is due to methane absorption and not to other factors, such as the absorptive properties of the cloud particles, which influence contrast at all wavelengths.

    The most prominent feature seen in all three filters is the polar stratospheric haze that makes Jupiter

  18. Characterization of penetration depth as a function of optical fiber separation at various absorption and scatter coefficients for a noninvasive metabolic sensor

    NASA Astrophysics Data System (ADS)

    DeMilo, Charles; Brukilacchio, Thomas; Soller, Babs R.; Soyemi, Olusola

    2004-06-01

    A visible-near IR (500-1,000nm) fiber optic sensor is under development that is intended to non-invasively assess muscle metabolism through the measurement of tissue pH and oxygen partial pressure. These parameters are calculated from the spectra of hemoglobin and myoglobin in muscle. The sensor consists of transmit (illumination) fibers and receive (detection) fibers that are coupled to a spectrometer. Light from the probe must penetrate below the surface of the skin and into a 5-10mm thick layer of muscle. A study was conducted to quantify the relationship between transmit and receive fiber separation and sensor penetration depth below the surface of the skin. A liquid phantom was created to replicate the absorption (μa) and reduced scatter coefficient (μs') profiles typically found in human blood and tissue. The phantom consisted of a solution of Intralipid and India ink in the appropriate concentrations to achieve desired reduced scatter coefficient and absorption profiles. The reduced scatter coefficient of the liquid phantom was achieved to an accuracy of +/-10% compared to previously published data. A fixed illumination fiber and translatable detector fiber were placed in the liquid phantom, and the fiber separation was varied from 3-40mm. Values of μa and μs' varied from 0.03-0.40 cm-1 and 5.0-15.0 cm-1 respectively. Results from the experiment demonstrate a strong correlation between penetration depth and fiber separation. Additionally, it was found that penetration depth was not substantially influenced by absorption and scatter concentration. As signal-to-noise is an important parameter in many non-invasive biomedical applications, the relative signal as a function of fiber separation was determined to follow an exponential relationship.

  19. Electron spectra derived from depth dose distributions.

    PubMed

    Faddegon, B A; Blevis, I

    2000-03-01

    The technique of extracting electron energy spectra from measured distributions of dose along the central axis of clinical electron beams is explored in detail. Clinical spectra measured with this simple spectroscopy tool are shown to be sufficient in accuracy and resolution for use in Monte Carlo treatment planning. A set of monoenergetic depth dose curves of appropriate energy spacing, precalculated with Monte Carlo for a simple beam model, are unfolded from the measured depth dose curve. The beam model is comprised of a point electron and photon source placed in vacuum with a source-to-surface distance of 100 cm. Systematic error introduced by this model affects the calculated depth dose curve by no more than 2%/2 mm. The component of the dose due to treatment head bremsstrahlung, subtracted prior to unfolding, is estimated from the thin-target Schiff spectrum within 0.3% of the maximum total dose (from electrons and photons) on the beam axis. Optimal unfolding parameters are chosen, based on physical principles. Unfolding is done with the public-domain code FERDO. Comparisons were made to previously published spectra measured with magnetic spectroscopy and to spectra we calculated with Monte Carlo treatment head simulation. The approach gives smooth spectra with an average resolution for the 27 beams studied of 16+/-3% of the mean peak energy. The mean peak energy of the magnetic spectrometer spectra was calculated within 2% for the AECL T20 scanning beam accelerators, 3% for the Philips SL25 scattering foil based machine. The number of low energy electrons in Monte Carlo spectra is estimated by unfolding with an accuracy of 2%, relative to the total number of electrons in the beam. Central axis depth dose curves calculated from unfolded spectra are within 0.5%/0.5 mm of measured and simulated depth dose curves, except near the practical range, where 1%/1 mm errors are evident. PMID:10757603

  20. Investigations on the electronic transport and piezoresistivity properties of Ni{sub 2−X}Mn{sub 1+X}Ga (X = 0 and 0.15) Heusler alloys under hydrostatic pressure

    SciTech Connect

    Devarajan, U.; Kalai Selvan, G.; Sivaprakash, P.; Arumugam, S.; Singh, Sanjay; Esakki Muthu, S.; Roy Barman, S.

    2014-12-22

    The resisitivity of Ni{sub 2−X}Mn{sub 1+X}Ga (X = 0 and 0.15) magnetic shape memory alloys has been investigated as a function of temperature (4–300 K) and hydrostatic pressure up to 30 kilobars. The resistivity is suppressed (X = 0) and enhanced (X = 0.15) with increasing pressure. A change in piezoresistivity with respect to pressure and temperature is observed. The negative and positive piezoresistivity increases with pressure for both the alloys. The residual resistivity and electron-electron scattering factor as a function of pressure reveal that for Ni{sub 2}MnGa the electron-electron scattering is predominant, while the X = 0.15 specimen is dominated by the electron-magnon scattering. The value of electron-electron scattering factor is positive for both the samples, and it is decreasing (negative trend) for Ni{sub 2}MnGa and increasing (positive trend) for X = 0.15 with pressure. The martensite transition temperature is found to be increased with the application of external pressure for both samples.

  1. PROCESS OF PRODUCING Cm$sup 244$ AND Cm$sup 24$$sup 5$

    DOEpatents

    Manning, W.M.; Studier, M.H.; Diamond, H.; Fields, P.R.

    1958-11-01

    A process is presented for producing Cm and Cm/sup 245/. The first step of the process consists in subjecting Pu/sup 2339/ to a high neutron flux and subsequently dissolving the irradiated material in HCl. The plutonium is then oxidized to at least the tetravalent state and the solution is contacted with an anion exchange resin, causing the plutonium values to be absorbed while the fission products and transplutonium elements remain in the effluent solution. The effluent solution is then contacted with a cation exchange resin causing the transplutonium, values to be absorbed while the fission products remain in solution. The cation exchange resin is then contacted with an aqueous citrate solution and tbe transplutonium elements are thereby differentially eluted in order of decreasing atomic weight, allowing collection of the desired fractions.

  2. Irrigation depth far exceeds water uptake depth in an oasis cropland in the middle reaches of Heihe River Basin

    PubMed Central

    Yang, Bin; Wen, Xuefa; Sun, Xiaomin

    2015-01-01

    Agricultural irrigation in the middle reaches of the Heihe River Basin consumes approximately 80% of the total river water. Whether the irrigation depth matches the water uptake depth of crops is one of the most important factors affecting the efficiency of irrigation water use. Our results indicated that the influence of plastic film on soil water δ18O was restricted to 0–30 cm soil depth. Based on a Bayesian model (MixSIR), we found that irrigated maize acquired water preferentially from 0–10 cm soil layer, with a median uptake proportion of 87 ± 15%. Additionally, maize utilised a mixture of irrigation and shallow soil water instead of absorbing the irrigation water directly. However, only 24.7 ± 5.5% of irrigation water remained in 0–10 cm soil layer, whereas 29.5 ± 2.8% and 38.4 ± 3.3% of the irrigation water infiltrated into 10–40 cm and 40–80 cm layers. During the 4 irrigation events, approximately 39% of the irrigation and rainwater infiltrated into soil layers below 80 cm. Reducing irrigation amount and developing water-saving irrigation methods will be important strategies for improving the efficiency of irrigation water use in this area. PMID:26463010

  3. Irrigation depth far exceeds water uptake depth in an oasis cropland in the middle reaches of Heihe River Basin.

    PubMed

    Yang, Bin; Wen, Xuefa; Sun, Xiaomin

    2015-01-01

    Agricultural irrigation in the middle reaches of the Heihe River Basin consumes approximately 80% of the total river water. Whether the irrigation depth matches the water uptake depth of crops is one of the most important factors affecting the efficiency of irrigation water use. Our results indicated that the influence of plastic film on soil water δ(18)O was restricted to 0-30 cm soil depth. Based on a Bayesian model (MixSIR), we found that irrigated maize acquired water preferentially from 0-10 cm soil layer, with a median uptake proportion of 87 ± 15%. Additionally, maize utilised a mixture of irrigation and shallow soil water instead of absorbing the irrigation water directly. However, only 24.7 ± 5.5% of irrigation water remained in 0-10 cm soil layer, whereas 29.5 ± 2.8% and 38.4 ± 3.3% of the irrigation water infiltrated into 10-40 cm and 40-80 cm layers. During the 4 irrigation events, approximately 39% of the irrigation and rainwater infiltrated into soil layers below 80 cm. Reducing irrigation amount and developing water-saving irrigation methods will be important strategies for improving the efficiency of irrigation water use in this area. PMID:26463010

  4. Irrigation depth far exceeds water uptake depth in an oasis cropland in the middle reaches of Heihe River Basin

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Wen, Xuefa; Sun, Xiaomin

    2015-10-01

    Agricultural irrigation in the middle reaches of the Heihe River Basin consumes approximately 80% of the total river water. Whether the irrigation depth matches the water uptake depth of crops is one of the most important factors affecting the efficiency of irrigation water use. Our results indicated that the influence of plastic film on soil water δ18O was restricted to 0-30 cm soil depth. Based on a Bayesian model (MixSIR), we found that irrigated maize acquired water preferentially from 0-10 cm soil layer, with a median uptake proportion of 87 ± 15%. Additionally, maize utilised a mixture of irrigation and shallow soil water instead of absorbing the irrigation water directly. However, only 24.7 ± 5.5% of irrigation water remained in 0-10 cm soil layer, whereas 29.5 ± 2.8% and 38.4 ± 3.3% of the irrigation water infiltrated into 10-40 cm and 40-80 cm layers. During the 4 irrigation events, approximately 39% of the irrigation and rainwater infiltrated into soil layers below 80 cm. Reducing irrigation amount and developing water-saving irrigation methods will be important strategies for improving the efficiency of irrigation water use in this area.

  5. Learning Sparse Representations of Depth

    NASA Astrophysics Data System (ADS)

    Tosic, Ivana; Olshausen, Bruno A.; Culpepper, Benjamin J.

    2011-09-01

    This paper introduces a new method for learning and inferring sparse representations of depth (disparity) maps. The proposed algorithm relaxes the usual assumption of the stationary noise model in sparse coding. This enables learning from data corrupted with spatially varying noise or uncertainty, typically obtained by laser range scanners or structured light depth cameras. Sparse representations are learned from the Middlebury database disparity maps and then exploited in a two-layer graphical model for inferring depth from stereo, by including a sparsity prior on the learned features. Since they capture higher-order dependencies in the depth structure, these priors can complement smoothness priors commonly used in depth inference based on Markov Random Field (MRF) models. Inference on the proposed graph is achieved using an alternating iterative optimization technique, where the first layer is solved using an existing MRF-based stereo matching algorithm, then held fixed as the second layer is solved using the proposed non-stationary sparse coding algorithm. This leads to a general method for improving solutions of state of the art MRF-based depth estimation algorithms. Our experimental results first show that depth inference using learned representations leads to state of the art denoising of depth maps obtained from laser range scanners and a time of flight camera. Furthermore, we show that adding sparse priors improves the results of two depth estimation methods: the classical graph cut algorithm by Boykov et al. and the more recent algorithm of Woodford et al.

  6. Magnetic depths to basalts: extension of spectral depths method

    NASA Astrophysics Data System (ADS)

    Clifton, Roger

    2015-11-01

    Although spectral depth determination has played a role in magnetic interpretation for over four decades, automating the procedure has been inhibited by the need for manual intervention. This paper introduces the concept of a slope spectrum of an equivalent layer, to be used in an automated depth interpretation algorithm suitable for application to very large datasets such as the complete Northern Territory aeromagnetic grid. In order to trace the extensive basalts across the Northern Territory, profiles of spectral depths have been obtained at 5 km intervals across the NT stitched grid of total magnetic intensity (TMI). Each profile is a graph from 0 to 1000 m of the probability of a magnetic layer occurring at each depth. Automating the collection of the 50 000 profiles required the development of a formula that relates slopes along the power spectrum to depths to an equivalent magnetic layer. Model slabs were populated with a large number of randomly located dipoles and their power spectra correlated with modelled depth to provide the formula. Depth profiles are too noisy to be used singly, but when a series of depth profiles are lined up side-by-side as a transect, significant magnetic layers can be traced for large distances. Transects frequently show a second layer. The formula is quite general in its derivation and would apply to any mid-latitude area where significant magnetic bodies can be modelled as extensive layers. Because the method requires a radial power spectrum, it fails to provide signal at depths much shallower than the flight line spacing. The method is convenient for a fast first pass at depth estimation, but its horizontal resolution is rather coarse and errors can be quite large.

  7. Organic matter evolution throughout a 100-cm ombrotrophic profile from an Italian floating mire

    NASA Astrophysics Data System (ADS)

    Zaccone, Claudio; D'Orazio, Valeria; Lobianco, Daniela; Miano, Teodoro M.

    2015-04-01

    The curious sight of an island floating and moving on a lake naturally, already described by Pliny the Elder in his Naturalis historia (AD 77-79), fascinated people from time immemorial. Floating mires are defined by the occurrence of emergent vegetation rooted in highly organic buoyant mats that rise and fall with changes in water level. Peat-forming floating mires could provide an exceptional tool for environmental studies, since much of their evolution, as well as the changes of the surrounding areas, is recorded in their peat deposits. A complete, 4-m deep peat core was collected in July 2012 from the floating island of Posta Fibreno, a relic mire in the Central Italy. This floating island has a diameter of ca. 30 m, a submerged thickness of about 3 m, and the vegetation is organized in concentric belts, from the Carex paniculata palisade to the Sphagnum centre. Here, some of the southernmost Italian populations of Sphagnum palustre occur. The 14C age dating of macrofossils removed from the sample at 360 cm of depth revealed that the island probably formed more than 500 yrs ago (435±20 yr BP). In the present work, we show preliminary results regarding the evolution of the organic matter along the first, ombrotrophic 100 cm of depth, hoping also to provide some insight into the possible mechanism of the evolution of this floating island. The 100 cm monolith was collected using a Wardenaar corer and cut frozen in 1-cm layers. It consists almost exclusively of Sphagnum mosses, often spaced out, in the top 20-30 cm, by leaves of Populus tremula that annually fell off. This section shows a very low bulk density, ranging from 0.017 and 0.059 g cm-3 (avg. value, 0.03±0.01 g cm-3), an average water content of 96.1±1.1%, and a gravimetric water content ranging between 14.3 and 41.5 gwater gdrypeat-1. The pH of porewaters was in the range 5-5.5. The C content along the profile ranged between 35 and 47% (avg., 41±1%), whereas the N between 0.3 and 0.9% (avg., 0.6±0

  8. A new atlas of infrared methane spectra between 1120 per cm and 1800 per cm

    NASA Technical Reports Server (NTRS)

    Blatherwick, R. D.; Goldman, A.; Lutz, B. L.; Silvaggio, P. M.; Boese, R. W.

    1979-01-01

    An atlas of 1339 methane absorption lines in the range 1120 to 1800 reciprocal centimeters, including the nu(4) and nu(2) bands, is presented. Laboratory spectra were obtained by a Nicolet Fourier transform Michelson interferometer with a resolution of approximately 0.06 reciprocal cm and a path length of 6.35 m of 0.98, 4.86 and 19.97 torr. Observed spectra are also compared with spectral intensities calculated line-by-line on the basis of tabulated intensities of the observed spectral lines.

  9. Depth-based computational photography

    NASA Astrophysics Data System (ADS)

    Liu, Ziwei; Xu, Tingfa; Liu, Jingdan; Li, Xiangmin; Zhao, Peng

    2015-05-01

    A depth-based computational photography model is proposed for all-in-focus image capture. A decomposition function, a defocus matrix, and a depth matrix are introduced to construct the photography model. The original image acquired from a camera can be decomposed into several sub-images on the basis of depth information. The defocus matrix can be deduced from the depth matrix according to the sensor defocus geometry for a thin lens model. And the depth matrix is reconstructed using the axial binocular stereo vision algorithm. This photography model adopts an energy functional minimization method to acquire the sharpest image pieces separately. The implementation of the photography method is described in detail. Experimental results for an actual scene demonstrate that our model is effective.

  10. Multistep joint bilateral depth upsampling

    NASA Astrophysics Data System (ADS)

    Riemens, A. K.; Gangwal, O. P.; Barenbrug, B.; Berretty, R.-P. M.

    2009-01-01

    Depth maps are used in many applications, e.g. 3D television, stereo matching, segmentation, etc. Often, depth maps are available at a lower resolution compared to the corresponding image data. For these applications, depth maps must be upsampled to the image resolution. Recently, joint bilateral filters are proposed to upsample depth maps in a single step. In this solution, a high-resolution output depth is computed as a weighted average of surrounding low-resolution depth values, where the weight calculation depends on spatial distance function and intensity range function on the related image data. Compared to that, we present two novel ideas. Firstly, we apply anti-alias prefiltering on the high-resolution image to derive an image at the same low resolution as the input depth map. The upsample filter uses samples from both the high-resolution and the low-resolution images in the range term of the bilateral filter. Secondly, we propose to perform the upsampling in multiple stages, refining the resolution by a factor of 2×2 at each stage. We show experimental results on the consequences of the aliasing issue, and we apply our method to two use cases: a high quality ground-truth depth map and a real-time generated depth map of lower quality. For the first use case a relatively small filter footprint is applied; the second use case benefits from a substantially larger footprint. These experiments show that the dual image resolution range function alleviates the aliasing artifacts and therefore improves the temporal stability of the output depth map. On both use cases, we achieved comparable or better image quality with respect to upsampling with the joint bilateral filter in a single step. On the former use case, we feature a reduction of a factor of 5 in computational cost, whereas on the latter use case, the cost saving is a factor of 50.

  11. O-band quantum-confined Stark effect optical modulator from Ge/Si{sub 0.15}Ge{sub 0.85} quantum wells by well thickness tuning

    SciTech Connect

    Chaisakul, Papichaya E-mail: papichaya.chaisakul@u-psud.fr; Marris-Morini, Delphine Vakarin, Vladyslav; Vivien, Laurent; Frigerio, Jacopo; Chrastina, Daniel; Isella, Giovanni

    2014-11-21

    We report an O-band optical modulator from a Ge/Si{sub 0.15}Ge{sub 0.85} multiple quantum well (MQW). Strong O-band optical modulation in devices commonly operating within E-band wavelength range can be achieved by simply decreasing the quantum well thickness. Both spectral photocurrent and optical transmission studies are performed to evaluate material characteristics and device performance from a surface-illuminated diode and a waveguide modulator, respectively. These results demonstrate the potential of using Ge/Si{sub 0.15}Ge{sub 0.85} MQWs for the realization of future on-chip wavelength-division multiplexing systems with optical modulators operating at different wavelengths over a wide spectral range.

  12. Strain-relaxation and critical thickness of epitaxial La1.85Sr0.15CuO4 films

    SciTech Connect

    Meyer, Tricia L; Jiang, Lu; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2015-12-08

    We report the thickness-dependent strain-relaxation behavior and the associated impacts upon the superconductivity in epitaxial La1.85Sr0.15CuO4 films grown on different substrates, which provide a range of strain. We have found that the critical thickness for the onset of superconductivity in La1.85Sr0.15CuO4 films is associated with the finite thickness effect and epitaxial strain. In particular, thin films with tensile strain greater than ~0.25% revealed no superconductivity. We attribute this phenomenon to the inherent formation of oxygen vacancies that can be minimized via strain relaxation.

  13. LARGE PIEZOELECTRIC EFFECT IN LOW-TEMPERATURE-SINTERED LEAD-FREE (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 THICK FILMS

    NASA Astrophysics Data System (ADS)

    Feng, Zuyong; Shi, Dongqi; Dou, Shixue; Hu, Yihua; Tang, Xingui

    2012-09-01

    High-quality piezoelectric (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 thick films with dense and homogenous microstructures were fabricated at a low sintering temperature (900°C) using a CuBi2O4 sintering aid. The 10 μm thick film exhibited a high longitudinal piezoelectric constant d33,eff of 210 pC/N with estimated unconstrained d33 value of 560 pC/N very close to that in the corresponding bulks. Such excellent piezoelectric effect in the low-temperature sintered (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 thick films is comparable to the case of lead-based PZT thick films, and may be a promising application in lead-free microdevices such as piezoelectric microelectromechanical systems (MEMS).

  14. [Effect of water depths on hydraulic performance of pond wetlands].

    PubMed

    Guo, Chang-Qiang; Dong, Bin; Liu, Jun-Jie; Liu, Chun-Guo; Feng, Da-Peng; Liu, Fang-Ping

    2014-11-01

    Pond wetlands have been widely used in the treatment of drainage water from paddy fields. However, wetland hydraulic performance and purification effects are affected by many factors, such as water depth, flow rate, aspect ratio and vegetation distribution, and the better understanding of these factors would be helpful to improve the quality of wetland design, operation and management. This paper analyzed the effect of three different water depths (20, 40 and 60 cm) on the hydraulic performance of pond wetland through the dye tracer experiments with Rhodamine WT. The hydraulic indices, i. e., effective volume ratio, nominal serial complete mixing tanks (N), hydraulic efficiency (λ), were selected for analysis through the hydraulic residence time distribution (RTD) curve. The results showed that the effective volume rate rose from 0.421 to 0.844 and the hydraulic efficiency from 0.281 to 0.604 when the water depth declined from 60 cm to 20 cm. This indicated that the wetland hydraulic performance improved as the water depth decreased. In addition, the hydraulic performance of the first half of the wetland was significantly better than that of the second half. The flow regime of the first half approached complete mixing because of the mixing index (N) approaching 1 and its effective volume rate was above 0.9 when the water depth was relatively low (20 and 40 cm). The normalized RTD curves demonstrated a good agreement between moment analysis parameters and hydraulic parameters, and a great consistency between the hydraulic parameters and moment index which was not affected by tail truncation error. The experimental study concluded that a lower water depth was favorable to improve the hydraulic performance of pond wetlands. PMID:25898628

  15. On evaluation of depth accuracy in consumer depth sensors

    NASA Astrophysics Data System (ADS)

    Abd Aziz, Azim Zaliha; Wei, Hong; Ferryman, James

    2015-12-01

    This paper presents an experimental study of different depth sensors. The aim is to answer the question, whether these sensors give accurate data for general depth image analysis. The study examines the depth accuracy between three popularly used depth sensors; ASUS Xtion Prolive, Kinect Xbox 360 and Kinect for Windows v2. The main attention is to study on the stability of pixels in the depth image captured at several different sensor-object distances by measuring the depth returned by the sensors within specified time intervals. The experimental results show that the fluctuation (mm) of the random selected pixels within the target area, increases with increasing distance to the sensor, especially on the Kinect for Xbox 360 and the Asus Xtion Prolive. Both of these sensors provide pixels fluctuation between 20mm and 30mm at a sensor-object distance beyond 1500mm. However, the pixel's stability of the Kinect for Windows v2 not affected much with the distance between the sensor and the object. The maximum fluctuation for all the selected pixels of Kinect for Windows v2 is approximately 5mm at sensor-object distance of between 800mm and 3000mm. Therefore, in the optimal distance, the best stability achieved.

  16. A comparative study of the growth of Tetraselmis sp. in large scale fixed depth and decreasing depth raceway ponds.

    PubMed

    Das, Probir; Thaher, Mahmoud Ibrahim; Hakim, Mohammed Abdul Quadir Mohd Abdul; Al-Jabri, Hareb Mohammed S J; Alghasal, Ghamza Saed H S

    2016-09-01

    In this study, an alternative approach was proposed where excess seawater would be added only during inoculation (DD) rather than daily addition (FD). Growth and metabolite contents of Tetraselmis sp. weren't affected for daily increase of 2% NaCl salinity. Tetraselmis sp. was then cultured in DD and FD pond. In DD pond, initial culture depth was 23.5cm and its depth reduced as no water was added; for FD pond, everyday sterilized seawater was added to maintain 20cm depth. DD pond had higher biomass productivity compared to FD pond, until DD pond was deeper than FD pond; metabolite content and FAME profile of Tetraselmis sp. were also similar in both cultures. Therefore, considering the simplicity in operation, halo tolerant microalgae can be grown in DD pond method. PMID:27235973

  17. Magnetic correlations in the magnetocaloric materials Mn3GaC and Mn3GaC0.85N0.15 studied by neutron polarization analysis and neutron depolarization

    NASA Astrophysics Data System (ADS)

    Çakr, Ö.; Acet, M.; Farle, M.; Wildes, A.

    2016-04-01

    Partially substituting carbon by nitrogen in the antiperovskite compound Mn3GaC increases the first order antiferromagnetic/ferromagnetic transition temperature and at the same time causes the high-temperature long-range ferromagnetism to weaken. To show that the weakening is related to the diminishing of ferromagnetic domain formation, we undertake neutron depolarization and neutron polarization analysis experiments on Mn3GaC and Mn3GaC0.85N0.15. Polarization analysis experiments show that strong ferromagnetic correlations are present at high temperatures in the paramagnetic states of both Mn3GaC and Mn3GaC0.85N0.15 and that these correlations vanish in the antiferromagnetic state. Neutron depolarization studies show that above the first order transition temperature, ferromagnetic domain formation is present in Mn3GaC but is absent in Mn3GaC0.85N0.15. The relationship between ferromagnetic domain formation and transitional hysteresis is brought forward for these two important magnetocaloric materials.

  18. Influence of nickel doping on oxygen-ionic conductivity of the n = 1 Ruddlesden-Popper Phases La1.85Ca0.15(Cu1-xNix)O4-δ (δ = 0.0905)

    NASA Astrophysics Data System (ADS)

    Midouni, Adnene; Houchati, Mohamed Ikbal; Othman, Walid Belhaj; Chniba-Boudjada, Nassira; Ceretti, Monica; Paulus, Werner; Jaouadi, Mouna; Hamzaoui, Ahmed Hichem

    2016-08-01

    The results of the synthesis and characterization of the optimally doped La1.85Ca0.15(Cu1-xNix)O4-δ solid solution with x = 0, 0.1, 0.2 and 0.3 are reported. The versatility of these La1.85Ca0.15(Cu1-xNix)O4-δ materials is explained on the basis of structural features and the ability to accommodate oxygen nonstoichiometry. According to powder X-ray and neutron diffraction data, La1.85Ca0.15(Cu1-xNix)O4-δ adopts the tetragonal structure with oxygen vacancies occurring preferentially at the Oap sites within the {(La/Ca)O} layers of the perovskite blocks and the oxygen deviation from stoichiometry δ was found to be δ=0.0905(6). The bulk conductivity indicated an Arrhenius-type thermally activated process and oxygen vacancies are the possible ionic charge carriers at T=270 °C. An increase of the conductivity was detected when Ni was introduced. With nickel ratio variation, a strong correlation was observed between the Cu(Ni)-Oap apical bond length variation and the conductivity variation through controlling the O2- ion migration.

  19. Reverse bias voltage testing of 8 cm x 8cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Woike, T.; Stotlar, S.; Lungu, C.

    1991-01-01

    A study is described of the reverse I-V characteristics of the largest space qualified silicon solar cells currently available (8 x 8 cm) and of reverse bias voltage (RBV) testing performed on these cells. This study includes production grade cells, both with and without cover glass. These cells span the typical output range seen in production. Initial characteristics of these cells are measured at both 28 and 60 C. These measurements show weak correlation between cell output and reverse characteristics. Analysis is presented to determine the proper conditions for RBV stress to simulate shadowing effects on a particular array design. After performing the RBV stress the characteristics of the stressed cells are remeasured. The degradation in cell performance is highly variable which exacerbates cell mismatching over time. The effect of this degradation on array lifetime is also discussed. Generalization of these results to other array configurations is also presented.

  20. Nitrogen fixation in sediments along a depth transect through the Eastern Boundary Upwelling Systems off Peru and Mauritania

    NASA Astrophysics Data System (ADS)

    Gier, J.; Sommer, S.; Löscher, C. R.; Dale, A.; Schmitz, R. A.; Treude, T.

    2015-12-01

    The distribution of benthic nitrogen (N2) fixation and its relevance for N cycling in the Eastern Boundary Upwelling Systems (EBUS) are still unknown. Recent studies confirm that benthic N2 fixation can be coupled to sulfate reduction (SR) and that several species of sulfate reducing bacteria have the genetic ability to fix N due to the presence of the gene encoding for the nitrogenase enzyme. We investigated benthic N2 fixation and SR in the Peruvian oxygen minimum zone at 12°S and in the Mauritanian upwelling system at 18°N along a depth transect. Sediments were retrieved by a multicorer and a benthic lander at six stations in both regions. Benthic N2 fixation occurred throughout the sediment in both EBUS. Off Peru the highest integrated (0-20 cm) N2 fixation rate of 0.4 mmol N/m2/d was measured inside the core of the OMZ at 253 m water depth. Off Mauritania the highest integrated (0-20 cm) N2 fixation rate of 0.15 mmol N/m2/d was measured at 90 m, coinciding with a low bottom water oxygen concentration (30 μM). N2 fixation depth profiles often overlapped with SR activity. Moreover, sequencing data yielded insights into the composition and diversity of the nifH gene pool in EBUS sediments. Interestingly, detected sequences in both EBUS clustered with SR bacteria, such as Desulfovibrio vulgaris and several of the novel detected clades belonged to uncultured diazotrophs. Our results suggest that N2 fixation and SR were coupled to a large extent in both regions. However, potential environmental factors controlling benthic diazotrophs in the EBUS appear to be the availability of sulfide and organic matter. Additionally, no inhibition of N2 fixation at high ammonium concentrations was found, which highlights gaps in our knowledge regards the interaction between ammonium availability and diazotrophy. Our results contribute to a better understanding of N cycling in EBUS sediments and sources of fixed N.

  1. Estimating the distribution of snow depth via artificial neural networks combined with MODIS snow cover area and ancillary topographic data

    NASA Astrophysics Data System (ADS)

    Hou, Jinliang; Huang, Chunlin

    2016-04-01

    samples, respectively; while R2 of 0.57 and 0.57, RMSE of 0.14 and 0.15, the mean absolute error of 5.34 and 5.38 cm for the corresponding multiple regression method.

  2. A correlation between the H I 21-cm absorption strength and impact parameter in external galaxies

    NASA Astrophysics Data System (ADS)

    Curran, S. J.; Reeves, S. N.; Allison, J. R.; Sadler, E. M.

    2016-04-01

    By combining the data from surveys for H I 21-cm absorption at various impact parameters in near-by galaxies, we report an anti-correlation between the 21-cm absorption strength (velocity integrated optical depth) and the impact parameter. Also, by combining the 21-cm absorption strength with that of the emission, giving the neutral hydrogen column density, N_{H I}, we find no evidence that the spin temperature of the gas (degenerate with the covering factor) varies significantly across the disk. This is consistent with the uniformity of spin temperature measured across the Galactic disk. Furthermore, comparison with the Galactic N_{H I} distribution suggests that intervening 21-cm absorption preferentially arises in disks of high inclinations (near face-on). We also investigate the hypothesis that 21-cm absorption is favourably detected towards compact radio sources. Although there is insufficient data to determine whether there is a higher detection rate towards quasar, rather than radio galaxy, sight-lines, the 21-cm detections intervene objects with a mean turnover frequency of <ν _{_TO}>≈ 5× 108 Hz, compared to <ν _{_TO}>≈ 1× 108 Hz for the non-detections. Since the turnover frequency is anti-correlated with radio source size, this does indicate a preferential bias for detection towards compact background radio sources.

  3. VLA observations of rapid 6 cm flux variations in alpha Ori

    NASA Technical Reports Server (NTRS)

    Bookbinder, J. A.; Stencel, R. E.; Drake, S. A.; Simon, T.; Linsky, J. L.; Florkowski, D.

    1987-01-01

    The red supergiant star alpha Ori was monitored with the Very Large Array (VLA). Thirteen observations at 6 cm show stochastic variations, at the 30 to 40 percent level, with no long term trend. All data was clipped and tapered in AIPS to minimize differences between VLA arrays. The calibration source varied by less than 10 percent over the same interval. The VLA observations of alpha Ori were continued, as well as alpha Her and alpha Sco, at both 2 and 6 cm, to confirm this result and search for long term trends. The stochastic 6 cm flux behavior, with 30 to 40 percent changes on all timescales from the shortest interval of 10 days to the longest, seems at odds with the 400 day periodic variations in U-band photometry and Mg II UV fluxes reported by Dupree, et al. The observed 6 cm flux was 25 percent below the 6 cm flux reported earlier this decade. Several models for the outer atmosphere of alpha Ori place the 6 cm optical depth unity location at several stellar radii above the optical photosphere. The rapid, stochastic variations reported are difficult to reconcile with almost any global process, such as pulsation, Alfven waves or periastron passage.

  4. A correlation between the H I 21-cm absorption strength and impact parameter in external galaxies

    NASA Astrophysics Data System (ADS)

    Curran, S. J.; Reeves, S. N.; Allison, J. R.; Sadler, E. M.

    2016-07-01

    By combining the data from surveys for H I 21-cm absorption at various impact parameters in near-by galaxies, we report an anti-correlation between the 21-cm absorption strength (velocity integrated optical depth) and the impact parameter. Also, by combining the 21-cm absorption strength with that of the emission, giving the neutral hydrogen column density, N_{H I}, we find no evidence that the spin temperature of the gas (degenerate with the covering factor) varies significantly across the disc. This is consistent with the uniformity of spin temperature measured across the Galactic disc. Furthermore, comparison with the Galactic N_{H I} distribution suggests that intervening 21-cm absorption preferentially arises in discs of high inclinations (near face-on). We also investigate the hypothesis that 21-cm absorption is favourably detected towards compact radio sources. Although there is insufficient data to determine whether there is a higher detection rate towards quasar, rather than radio galaxy, sight-lines, the 21-cm detections intervene objects with a mean turnover frequency of < ν _{_TO}rangle ≈ 5× 108 Hz, compared to < ν _{_TO}rangle ≈ 1× 108 Hz for the non-detections. Since the turnover frequency is anti-correlated with radio source size, this does indicate a preferential bias for detection towards compact background radio sources.

  5. New H I 21-cm absorbers at low and intermediate redshifts

    NASA Astrophysics Data System (ADS)

    Zwaan, M. A.; Liske, J.; Péroux, C.; Murphy, M. T.; Bouché, N.; Curran, S. J.; Biggs, A. D.

    2015-10-01

    We present the results of a survey for intervening H I 21-cm absorbers at intermediate and low redshift (0 < z < 1.2). For our total sample of 24 systems, we obtained high-quality data for 17 systems, the other seven being severely affected by radio frequency interference (RFI). Five of our targets are low-redshift (z < 0.17) optical galaxies with small impact parameters (<20 kpc) towards radio-bright background sources. Two of these were detected in 21-cm absorption, showing narrow, high optical depth absorption profiles, the narrowest having a velocity dispersion of only 1.5 km s- 1, which puts an upper limit on the kinetic temperature of Tk < 270 K. Combining our observations with results from the literature, we measure a weak anticorrelation between impact parameter and integral optical depth in local (z < 0.5) 21-cm absorbers. Of 11 Ca II and Mg II systems searched, two were detected in 21-cm absorption, and six were affected by RFI to a level that precludes a detection. For these two systems at z ˜ 0.6, we measure spin temperatures of Ts = (65 ± 17) K and Ts > 180 K. A subset of our systems was also searched for OH absorption, but no detections were made.

  6. From 20cm to 1.5m: Is Digging Deeper Necessary?

    NASA Astrophysics Data System (ADS)

    Fissore, C.; Nater, E. A.; Dalzell, B. J.; Kolka, R.; Perry, C.

    2011-12-01

    Quantification of belowground carbon (C) currently stored in forest ecosystems is far from complete, especially for deeper soil horizons. Given logistical difficulties of sampling deep soils over large areas, much attention has been given to estimate deep SOC stocks indirectly. It is unknown whether C content in the top 20 cm of the mineral soil is an effective index for deep soil C storage across broad ranges of climate, forest type, and soil characteristics. The US Forest Service has a large record of aboveground and belowground (up to 20 cm depth) C data that could potentially be used to quantify deep SOC stocks if a suitable indirect estimation method can be developed. We followed and extended USDA FS Forest Inventory Analysis protocols to sample forest sites in the Midwest U.S. to determine C content up to 1.5m depth over a range of forest and soil types. Preliminary results show that, at hardwood sites, C percent in the top 20 cm of the mineral soil predicted only 28% of deep soil C in sandy soils and 20% in loamy soils. On a mass basis (mg C/cm3), such relationship was even weaker, suggesting that a number of biophysical variables affect SOC storage along the soil profile. Ongoing analyses will identify whether including additional factors such as forest type and soil chemical-physical characteristics will strengthen this relationship. The use of fractionation techniques and stable and radioactive isotopes will help illustrate SOC stabilization mechanisms.

  7. Medium-depth chemical peels.

    PubMed

    Monheit, G D

    2001-07-01

    The combination medium-depth chemical peel (Jessner's solution +35% TCA) has been accepted as a safe, reliable, and effective method for the treatment of moderate photoaging skin. This article discusses the procedure in detail, including postoperative considerations. PMID:11599398

  8. Teaching Depth of Field Concept

    ERIC Educational Resources Information Center

    Ross, Frederick C.; Smith, Rodney J.

    1978-01-01

    This activity utilizes an overhead projector, a wax pencil, and a petri-dish to demonstrate the depth of field concept to students learning the use of the microscope. Illustrations and directions are included. (MA)

  9. Electrochemical properties of the Sm 0.5Sr 0.5CoO 3-La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3 (LSGMC5)/LSGMC5 interface modified by an LSGMC5 interlayer synthesized using the citrate method

    NASA Astrophysics Data System (ADS)

    Wang, Shizhong; Zhong, Hao; Zou, Yuman

    A La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3 (LSGMC5) interlayer synthesized using the citrate method was added between an Sm 0.5Sr 0.5CoO 3 (SSC)-LSGMC5 electrode and an LSGMC5 electrolyte pellet synthesized using a solid-state reaction, and we found that the electrode activity was improved dramatically. The SEM images of the samples demonstrated that the contact between the electrode and the interlayer was much better than the contact between the electrode and electrolyte without the interlayer. The addition of the interlayer resulted in an increased three-phase boundary length and electrode/electrolyte two-phase interfacial area. An SSC-LSGMC5 electrode sintered at 1123 K deposited onto an interlayer sintered at 1673 K exhibited the highest performance among the samples studied. The electrode resistance was about 0.08 Ω cm 2 at near equilibrium conditions, and the cathodic overpotential at a current density of 1 A cm -2 was only about 70 mV at 973 K in oxygen. The introduction of the interlayer did not change the oxygen reaction mechanism, and the significant increase in electrode performance was due to the increase in the number of active sites for oxygen reduction.

  10. Large-Scale Surveys of Snow Depth on Arctic Sea Ice from Operation IceBridge

    NASA Technical Reports Server (NTRS)

    Kurtz, Nathan T.; Farrell, Sinead L.

    2011-01-01

    We show the first results of a large ]scale survey of snow depth on Arctic sea ice from NASA fs Operation IceBridge snow radar system for the 2009 season and compare the data to climatological snow depth values established over the 1954.1991 time period. For multiyear ice, the mean radar derived snow depth is 33.1 cm and the corresponding mean climatological snow depth is 33.4 cm. The small mean difference suggests consistency between contemporary estimates of snow depth with the historical climatology for the multiyear ice region of the Arctic. A 16.5 cm mean difference (climatology minus radar) is observed for first year ice areas suggesting that the increasingly seasonal sea ice cover of the Arctic Ocean has led to an overall loss of snow as the region has transitioned away from a dominantly multiyear ice cover.

  11. Mechanistic evaluation of virus clearance by depth filtration.

    PubMed

    Venkiteshwaran, Adith; Fogle, Jace; Patnaik, Purbasa; Kowle, Ron; Chen, Dayue

    2015-01-01

    Virus clearance by depth filtration has not been well-understood mechanistically due to lack of quantitative data on filter charge characteristics and absence of systematic studies. It is generally believed that both electrostatic interactions and sized based mechanical entrapment contribute to virus clearance by depth filtration. In order to establish whether the effectiveness of virus clearance correlates with the charge characteristics of a given depth filter, a counter-ion displacement technique was employed to determine the ionic capacity for several depth filters. Two depth filters (Millipore B1HC and X0HC) with significant differences in ionic capacities were selected and evaluated for their ability to eliminate viruses. The high ionic capacity X0HC filter showed complete porcine parvovirus (PPV) clearance (eliminating the spiked viruses to below the limit of detection) under low conductivity conditions (≤2.5 mS/cm), achieving a log10 reduction factor (LRF) of > 4.8. On the other hand, the low ionic capacity B1HC filter achieved only ∼2.1-3.0 LRF of PPV clearance under the same conditions. These results indicate that parvovirus clearance by these two depth filters are mainly achieved via electrostatic interactions between the filters and PPV. When much larger xenotropic murine leukemia virus (XMuLV) was used as the model virus, complete retrovirus clearance was obtained under all conditions evaluated for both depth filters, suggesting the involvement of mechanisms other than just electrostatic interactions in XMuLV clearance. PMID:25683459

  12. Crack depth measurement in concrete using diffuse ultrasound

    NASA Astrophysics Data System (ADS)

    In, Chi Won; Kim, Jin-Yeon; Jacobs, Laurence L.; Kurtis, Kimberly

    2012-05-01

    Cracking in concrete structures is problematic because these cracks can significantly influence the stability of a concrete structure and compromise its durability. The first step to evaluate the serviceability of an in-field concrete structure is to have accurate information on existing crack depth. It is thus of paramount importance to be able to accurately determine the depth of cracks in these concrete structures. This research employs a diffusive ultrasonic technique to measure the depth of surface cracks in concrete. Ultrasonic measurements on a 25.4 × 33 × 60.96 cm3 concrete block containing an artificial crack with varying depths from 2.54 to 10.16 cm are conducted. Contact transducers with one transmitting and the other receiving the ultrasonic signals are mounted on the concrete surface on opposite sides of the crack. A pulse signal with the duration of 2μs is transmitted. In this frequency regime, wavelengths are sufficiently short (comparable with the aggregate size) so that a diffuse ultrasonic signal is detected. The arrival of the diffuse ultrasonic energy at the receiver is delayed by the existence of the crack. This lag-time and the diffusivity of the concrete sample are measured, and a finite element model is employed to solve the inverse problem to determine the crack depth from these measured diffuse ultrasonic parameters.

  13. Monitoring the Depth of Anaesthesia

    PubMed Central

    Musizza, Bojan; Ribaric, Samo

    2010-01-01

    One of the current challenges in medicine is monitoring the patients’ depth of general anaesthesia (DGA). Accurate assessment of the depth of anaesthesia contributes to tailoring drug administration to the individual patient, thus preventing awareness or excessive anaesthetic depth and improving patients’ outcomes. In the past decade, there has been a significant increase in the number of studies on the development, comparison and validation of commercial devices that estimate the DGA by analyzing electrical activity of the brain (i.e., evoked potentials or brain waves). In this paper we review the most frequently used sensors and mathematical methods for monitoring the DGA, their validation in clinical practice and discuss the central question of whether these approaches can, compared to other conventional methods, reduce the risk of patient awareness during surgical procedures. PMID:22163504

  14. Morphology and magneto-transport properties of electron doped La{sub 0.85}Te{sub 0.15}MnO{sub 3} thin film deposited on LaAlO{sub 3} substrate

    SciTech Connect

    Bhat, Irshad; Husain, Shahid; Patil, S.I.

    2014-09-15

    Graphical abstract: Resistivity versus temperature plots of La{sub 0.85}Te{sub 0.15}MnO{sub 3} thin film under the applied magnetic field of 0 T, 5 T and 8 T. - Highlights: • La{sub 0.85}Te{sub 0.15}MnO{sub 3} manganite thin film is deposited on LaAlO{sub 3} using PLD technique. • Film is deposited at 750 °C, and is highly crystalline, single phase and c-axis oriented. • The film consists of grains with an average diameter of 60 nm. • Resistivity plots display double insulator-metal transitions. • XPS results confirm the electron doped (n-type) nature of the film. - Abstract: We report the structural, electronic transport and X-ray photoemission spectroscopic study of 100 nm thin film of La{sub 0.85}Te{sub 0.15}MnO{sub 3} grown on (0 0 1) LaAlO{sub 3} single crystal substrate by pulsed laser deposition. XRD results confirm that the film has good crystalline quality, single phase, and has a c-axis orientation. The atomic force microscopic (AFM) results showed that the film consists of grains with an average diameter of 60 nm. The resistivity measurement showed double insulator-metal transitions in absence and as well as in presence of the magnetic field. The resistivity peaks are ascribed to the intrinsic contribution of LTMO film and the tunnelling of spin-polarized electrons at grain boundaries. X-ray photoemission spectroscopy measurements suggest that Te ions are in the Te{sup 4+} state, while the Mn ions are forced to stay in the Mn{sup 2+} and Mn{sup 3+} valence state.

  15. Microwave property improvement of Ca[(Li1/3Nb2/3)0.95Zr0.15]O3+δ perovskite by A-site substitution

    NASA Astrophysics Data System (ADS)

    Hu, Mingzhe; Xiong, Gang; Ding, Zhao

    2016-04-01

    The crystal structure and microwave dielectric properties of Ca[(Li1/3Nb2/3)0.95Zr0.15]O3+δ ceramic (CLNZ) are tuned by A-site substitution of Sr2+ and Ba2+ ions in the present paper. The tuning effect on the crystal structure is investigated by the X-ray diffraction (XRD) pattern and it illustrates that single phase of orthorhombic perovskite structure is formed, however, minor amount of BaNb2O6-type second phase is also detected in (Ca1‑xBax)[(Li1/3Nb2/3)0.95Zr0.15]O3+δ ceramics (CBLNZ) in the range of x ≥ 0.025, while pure perovskite phase is obtained in (Ca1‑xSrx)[(Li1/3Nb2/3)0.95Zr0.15]O3+δ ceramics (CSLNZ) in the whole investigation range of 0 ≤ x ≤ 0.2. With the increase of x value, the unit cell volumes of both CBLNZ and CSLNZ perovskites gradually expand, which results in the degradation of the vibration bond strength between the B-site ions and oxygen in the perovskites. The microscopic structure related thermal parameters in CSLNZ and CBLNZ perovskites are analyzed in terms of Clausius-Mossotti equation to reveal the original contributors in the temperature coefficients. The results show that both Sr2+ and Ba2+ substitution can effectively improve the permittivity and Qf value, especially, improve the temperature coefficient of CLNZ ceramic in a certain range.

  16. Sintering of BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta) with/without SrTiO3 Dopant

    NASA Technical Reports Server (NTRS)

    Dynys, F.; Sayir, A.; Heimann, P. J.

    2004-01-01

    The perovskite composition, BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta), displays excellent protonic conduction at high temperatures making it a desirable candidate for hydrogen separation membranes. This paper reports on the sintering behavior of BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta) powders doped with SrTiO3. Two methods were used to synthesize BaCe(sub 0.85)Y(sub 0.15)O(sub 3-delta) powders: (1) solid state reaction and (2) wet chemical co-precipitation. Co-precipitated powder crystallized into the perovskite phase at 1000 C for 4 hrs. Complete reaction and crystallization of the perovskite phase by solid state was achieved by calcining at 1200 C for 24 hrs. Solid state synthesis produced a coarser powder with an average particle size of 1.3 microns and surface area of 0.74 sq m/g. Co-precipitation produced a finer powder with a average particle size of 65 nm and surface area of 14.9 sq m/g. Powders were doped with 1, 2, 5, and 10 mole % SrTiO3. Samples were sintered at 1450 C, 1550 C and 1650 C. SrTiO3 enhances sintering, optimal dopant level is different for powders synthesized by solid state and co-precipitation. Both powders exhibit similar grain growth behavior. Dopant levels of 5 and 10 mole % SrTiO3 significantly enhances the grain size.

  17. The structure, magnetostriction, and hysteresis of (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys

    NASA Astrophysics Data System (ADS)

    Wang, Bowen; Lv, Yan; Li, Guolu; Huang, Wenmei; Weng, Ling; Cui, Baozhi

    2015-05-01

    The (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys were prepared in an arc furnace under high purity argon. The as-cast samples wrapped in Mo foil were sealed in a silica tube filled with high purity argon and were homogenized at 1000 °C for 1 day and at 950 °C for 5 days. Then, the homogenized specimens with 5 mm in diameter and 8 mm in length were annealed under the magnetic field of 320 kA/m. The static measurement of magnetostriction (λ//, λ⊥) was made by standard strain gauge, and the magnetization M was measured by a vibrating sample magnetometer. It is found that the main phase of annealed (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys is the (Tb,Dy,Ho)Fe2 phase with the MgCu2-type structure. The magnetostriction λ// and magnetization M of (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys increases with increasing x from x = 0.1 to x = 0.3 when H < 240 kA/m. The hysteresis becomes small with increasing x when x ≤ 0.3. For magnetically annealed rod alloys, the magnetostriction markedly increases and reaches 1080 × 10-6 for x = 0.3 when H = 240 kA/m.

  18. Flexible depth of field photography.

    PubMed

    Kuthirummal, Sujit; Nagahara, Hajime; Zhou, Changyin; Nayar, Shree K

    2011-01-01

    The range of scene depths that appear focused in an image is known as the depth of field (DOF). Conventional cameras are limited by a fundamental trade-off between depth of field and signal-to-noise ratio (SNR). For a dark scene, the aperture of the lens must be opened up to maintain SNR, which causes the DOF to reduce. Also, today's cameras have DOFs that correspond to a single slab that is perpendicular to the optical axis. In this paper, we present an imaging system that enables one to control the DOF in new and powerful ways. Our approach is to vary the position and/or orientation of the image detector during the integration time of a single photograph. Even when the detector motion is very small (tens of microns), a large range of scene depths (several meters) is captured, both in and out of focus. Our prototype camera uses a micro-actuator to translate the detector along the optical axis during image integration. Using this device, we demonstrate four applications of flexible DOF. First, we describe extended DOF where a large depth range is captured with a very wide aperture (low noise) but with nearly depth-independent defocus blur. Deconvolving a captured image with a single blur kernel gives an image with extended DOF and high SNR. Next, we show the capture of images with discontinuous DOFs. For instance, near and far objects can be imaged with sharpness, while objects in between are severely blurred. Third, we show that our camera can capture images with tilted DOFs (Scheimpflug imaging) without tilting the image detector. Finally, we demonstrate how our camera can be used to realize nonplanar DOFs. We believe flexible DOF imaging can open a new creative dimension in photography and lead to new capabilities in scientific imaging, vision, and graphics. PMID:21088319

  19. Synthesis, structural and vibrational properties of Bi{sub 0.8}La{sub 0.15}A{sub 0.05}FeO{sub 3} (A = Ca, Sr)

    SciTech Connect

    Sharma, Poorva E-mail: poorva.aks@gmail.com; Kumar, Ashwini; Varshney, Dinesh E-mail: poorva.aks@gmail.com

    2015-06-24

    The polycrystalline Bi{sub 0.8}La{sub 0.15}A{sub 0.05}FeO{sub 3} (A = Ca, Sr) was synthesized by solid state reaction route to study the structural and vibrational properties. X-ray diffraction patterns confirmed the formation of single-phase perovskite structure. Rietveld–refined crystal structure parameters revealed the existence of rhombohedral R3c symmetry in the prepared sample. The blue shift of phonon modes is attributed to lower atomic mass of La{sup 3+} and A = (Ca, Sr) substitution at Bi site in BiFeO{sub 3}.

  20. Study of the angular-dependence of the L-alpha and L-beta radiation produced by 0-15 kev photons incident on Au targets of various thicknesses

    NASA Astrophysics Data System (ADS)

    Requena, Sebastian; Williams, Scott

    2011-03-01

    We report the results of experiments involving the L-alpha and L-beta x-ray lines produced by 0-15 keV bremsstrahlung incident on gold targets of various thicknesses at forward-scattered angles ranging from 20 to 160 degrees. Previous reports [1, 2] have shown the L-beta peaks to be isotropic and the L-alpha peaks to be anisotropic due to the symmetry/asymmetry associated with the orbital being filled during the transition. The relative intensities are compared to the predictions of the Monte Carlo code, PENELOPE.

  1. Alpha self-irradiation effect on the local structure of the U{sub 0.85}Am{sub 0.15}O{sub 2{+-}x} solid solution

    SciTech Connect

    Prieur, D.; Martin, P.M.; Scheinost, A.C.; Dehaudt, P.

    2012-10-15

    Uranium-americium mixed oxides are promising fuels for achieving an efficient Am recycling. Previous studies on U{sub 0.85}Am{sub 0.15}O{sub 2{+-}x} materials showed that the high {alpha} activity of {sup 241}Am induces pellet swelling which is a major issue for cladding materials design. In this context, X-ray Diffraction and X-ray Absorption Spectroscopy measurements were used to study self-irradiation effects on U{sub 0.85}Am{sub 0.15}O{sub 2{+-}x} local structure and to correlate these results with those obtained at the macroscopic scale. For a cumulative {alpha} decay dose equal to 0.28 dpa, it was shown that non-defective fluorite solid solutions were achieved and therefore, that the fluorite structure is stable for the studied doses. In addition, both interatomic distance and lattice parameter expansions were observed, which only partially explains the macroscopic swelling. As expected, an increase of the structural disorder with self-irradiation was also observed. - Graphical abstract: X-ray Diffraction and X-ray Absorption Spectroscopy measurements were performed on U{sub 0.85}Am{sub 0.15}O{sub 2{+-}x}, exhibiting various cumulative {alpha} decay doses, in order to study self-irradiation effects on local structure and to correlate these results with those obtained at the macroscopic scale. Thus, it was shown that the fluorite structure is stable for the studied doses. In addition, both interatomic distance and lattice parameter expansions were observed, explaining partially the macroscopic swelling. Highlights: Black-Right-Pointing-Pointer Non-defective fluorite U{sub 0.85}Am{sub 0.15}O{sub 2{+-}x} solid solutions were achieved. Black-Right-Pointing-Pointer The fluorite structure is stable for the studied doses. Black-Right-Pointing-Pointer A lattice parameter increase was observed, which partially explains the macroscopic swelling. Black-Right-Pointing-Pointer The increase of the structural disorder can be understood from the ballistic effect associated

  2. Erratum: VLA H92α and H115β Recombination Line Observations of the Galactic Center H II Regions: The Sickle (G0.18-0.04) and the Pistol (G0.15-0.05)

    NASA Astrophysics Data System (ADS)

    Lang, Cornelia C. Lang; Goss, W. M.; Wood, D. O. S.

    1997-06-01

    In the paper ``VLA H92α and H115β Recombination Line Observations of the Galactic Center H II Regions: The Sickle (G0.18-0.04) and the Pistol (G0.15-0.05)'' by Cornelia C. Lang, W. M. Goss, and D. O. S. Wood (ApJ, 474, 275 [1997]), an error occurred in Figure 9. Figure 9a was printed twice, and Figure 9b was omitted. The correct version of Figure 9b is presented here.

  3. Legacy effects of grassland management on soil carbon to depth.

    PubMed

    Ward, Susan E; Smart, Simon M; Quirk, Helen; Tallowin, Jerry R B; Mortimer, Simon R; Shiel, Robert S; Wilby, Andrew; Bardgett, Richard D

    2016-08-01

    The importance of managing land to optimize carbon sequestration for climate change mitigation is widely recognized, with grasslands being identified as having the potential to sequester additional carbon. However, most soil carbon inventories only consider surface soils, and most large-scale surveys group ecosystems into broad habitats without considering management intensity. Consequently, little is known about the quantity of deep soil carbon and its sensitivity to management. From a nationwide survey of grassland soils to 1 m depth, we show that carbon in grassland soils is vulnerable to management and that these management effects can be detected to considerable depth down the soil profile, albeit at decreasing significance with depth. Carbon concentrations in soil decreased as management intensity increased, but greatest soil carbon stocks (accounting for bulk density differences), were at intermediate levels of management. Our study also highlights the considerable amounts of carbon in subsurface soil below 30 cm, which is missed by standard carbon inventories. We estimate grassland soil carbon in Great Britain to be 2097 Tg C to a depth of 1 m, with ~60% of this carbon being below 30 cm. Total stocks of soil carbon (t ha(-1) ) to 1 m depth were 10.7% greater at intermediate relative to intensive management, which equates to 10.1 t ha(-1) in surface soils (0-30 cm), and 13.7 t ha(-1) in soils from 30 to 100 cm depth. Our findings highlight the existence of substantial carbon stocks at depth in grassland soils that are sensitive to management. This is of high relevance globally, given the extent of land cover and large stocks of carbon held in temperate managed grasslands. Our findings have implications for the future management of grasslands for carbon storage and climate mitigation, and for global carbon models which do not currently account for changes in soil carbon to depth with management. PMID:26854892

  4. Sampling Depths, Depth Shifts, and Depth Resolutions for Bi(n)(+) Ion Analysis in Argon Gas Cluster Depth Profiles.

    PubMed

    Havelund, R; Seah, M P; Gilmore, I S

    2016-03-10

    Gas cluster sputter depth profiling is increasingly used for the spatially resolved chemical analysis and imaging of organic materials. Here, a study is reported of the sampling depth in secondary ion mass spectrometry depth profiling. It is shown that effects of the sampling depth leads to apparent shifts in depth profiles of Irganox 3114 delta layers in Irganox 1010 sputtered, in the dual beam mode, using 5 keV Ar₂₀₀₀⁺ ions and analyzed with Bi(q+), Bi₃(q+) and Bi₅(q+) ions (q = 1 or 2) with energies between 13 and 50 keV. The profiles show sharp delta layers, broadened from their intrinsic 1 nm thickness to full widths at half-maxima (fwhm's) of 8-12 nm. For different secondary ions, the centroids of the measured delta layers are shifted deeper or shallower by up to 3 nm from the position measured for the large, 564.36 Da (C₃₃H₄₆N₃O₅⁻) characteristic ion for Irganox 3114 used to define a reference position. The shifts are linear with the Bi(n)(q+) beam energy and are greatest for Bi₃(q+), slightly less for Bi₅(q+) with its wider or less deep craters, and significantly less for Bi(q+) where the sputtering yield is very low and the primary ion penetrates more deeply. The shifts increase the fwhm’s of the delta layers in a manner consistent with a linearly falling generation and escape depth distribution function (GEDDF) for the emitted secondary ions, relevant for a paraboloid shaped crater. The total depth of this GEDDF is 3.7 times the delta layer shifts. The greatest effect is for the peaks with the greatest shifts, i.e. Bi₃(q+) at the highest energy, and for the smaller fragments. It is recommended that low energies be used for the analysis beam and that carefully selected, large, secondary ion fragments are used for measuring depth distributions, or that the analysis be made in the single beam mode using the sputtering Ar cluster ions also for analysis. PMID:26883085

  5. Determining snow depth using Ku-band interferometric synthetic aperture radar (InSAR)

    NASA Astrophysics Data System (ADS)

    Evans, J. R.; Kruse, F. A.; Bickel, D. L.; Dunkel, Ralf

    2014-05-01

    Monitoring seasonal snow accumulation is important for evaluation of snow models, for short- and long-term snow cover monitoring, and for both military and civilian activities in cold climates. Improved spatial analysis of snow depth and volume can help decision makers plan for future events and mitigate risk. Current snow depth measurement methods fall short of operational requirements. This research explored a new approach for determining snow depth using Ku-band multi-pass (monostatic) airborne interferometric synthetic aperture radar (InSAR). A perturbation method that isolated and compared high frequency terrain phase to elevation was used to generate Snow-Off and Snow-On DEMs from the InSAR phase data. Differencing the InSAR DEMs determined elevation change caused by accumulated snow. Comparison of InSAR snow depths to manual snow depth measurements indicated average InSAR snow depth errors of -8cm, 95cm, -49cm, 176cm, 87cm, and 42cm for six SAR pairs. The source of these errors appears to be mostly related to uncorrected slope and tilt in fitted low frequency planes. Results show that this technique has promise but accuracy could be substantially improved by the use of bistatic SAR systems, which would allow for more stable and measurable interferometric baselines.

  6. Effects of prescription depth, cylinder size, treatment length, tip space, and curved end on doses in high-dose-rate vaginal brachytherapy

    SciTech Connect

    Li Shidong . E-mail: sli1@hfhs.org; Aref, Ibrahim; Walker, Eleanor; Movsas, Benjamin

    2007-03-15

    Purpose: To determine the effects of the prescription depth, cylinder size, treatment length, tip space, and curved end on high-dose-rate vaginal brachytherapy (HDR-VBT) of endometrial cancer. Methods and Materials: Treatment plans were prescribed and optimized based on points at the cylinder surface or at 0.5-cm depth. Cylinder sizes ranging from 2 to 4 cm in diameter, and treatment lengths ranging from 3 to 8 cm were used. Dose points in various depths were precisely defined along the cylinder dome. The given dose and dose uniformity to a depth of interest were measured by the mean dose (MD) and standard deviation (SD), respectively, among the dose points belonging to the depth. Dose fall-off beyond the 0.5 cm treatment depth was determined by the ratio of MD at 0.75-cm depth to MD at 0.5-cm depth. Results: Dose distribution varies significantly with different prescriptions. The surface prescription provides more uniform doses at all depths in the target volume, whereas the 0.5-cm depth prescription creates larger dose variations at the cylinder surface. Dosimetric uncertainty increases significantly (>30%) with shorter tip space. Extreme hot (>150%) and cold spots (<60%) occur if no optimization points were placed at the curved end. Conclusions: Instead of prescribing to a depth of 0.5 cm, increasing the dose per fraction and prescribing to the surface with the exact surface points around the cylinder dome appears to be the optimal approach.

  7. Radar Images of the Ice Deposits at Mercury's North Pole at 70-cm Wavelength

    NASA Astrophysics Data System (ADS)

    Black, Gregory J.; Campbell, D. B.; Harmon, J. K.

    2009-09-01

    Radar imaging of Mercury's north polar region was done using the Arecibo Observatory's 70-centimeter wavelength radar system during the inferior conjunction of July 1999. We have clearly detected the highly reflective region at Mercury's north pole first identified in radar images at the shorter wavelengths 3.6-cm and 13-cm [1,2]. The average 70-cm wavelength reflectivity of this polar region is similar to that measured at the other wavelengths over a comparable area, and the polarization ratio of 0.87 is only slightly lower. This ratio is formed from echo power returned in both circular polarizations when only one polarization is transmitted, and the observed depolarization is indicative of a multiple scattering mechanism. High resolution delay-Doppler radar maps at 3.5-cm and 13-cm wavelengths (most recently [3,4]) have demonstrated that these enhancements are located within craters near the pole, suggesting they result from ice deposits in these cold permanently shadowed depressions. Characterizing these areas is also a key goal of the current MESSENGER mission. The low absorption coefficient of ice at radio wavelengths can permit sub-surface multiple scattering mechanisms and enhance radar backscattering. Persistence of this effect over more than an order of magnitude in wavelength scale has implications for the depth and thickness of the deposits. A strong effect at the shortest wavelength implies a thin attenuating overburden. Since multiple scattering mechanisms generally require a medium many wavelengths thick, the strong effect at the long wavelength may set a minimum depth of the deposits. We acknowledge support from the NASA PG&G Program. Arecibo Observatory is part of the National Astronomy and Ionosphere Center, operated by Cornell University under cooperative agreement with the NSF. [1] Slade et al., 1992, Science 258, 635; [2] Harmon & Slade, 1992, Science 258, 640; [3] Harmon et al., 1994, Nature 369, 213; [4] Harcke, 2005, PhD Thesis, Stanford.

  8. Lessons Learned From CM-2 Modal Testing and Analysis

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Goodnight, Thomas W.; Carney, Kelly S.; Otten, Kim D.

    2002-01-01

    The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS-107 in the SPACEHAB Double Research Module. The CM-2 flight hardware is installed into SPACEHAB single and double racks. The CM-2 flight hardware was vibration tested in the launch configuration to characterize the structure's modal response. Cross-orthogonality between test and analysis mode shapes were used to assess model correlation. Lessons learned for pre-test planning and model verification are discussed.

  9. Visualization on massively parallel computers using CM/AVS

    SciTech Connect

    Krogh, M.F.; Hansen, C.D.

    1993-09-01

    CM/AVS is a visualization environment for the massively parallel CM-5 from Thinking Machines. It provides a backend to the standard commercially available AVS visualization product. At the Advanced Computing Laboratory at Los Alamos National Laboratory, we have been experimenting and utilizing this software within our visualization environment. This paper describes our experiences with CM/AVS. The conclusions reached are applicable to any implimentation of visualization software within a massively parallel computing environment.

  10. Energy Levels of the Nitrate Radical Below 2000 CM-1

    NASA Astrophysics Data System (ADS)

    Stanton, J. F.; Simmons, C. S.

    2012-06-01

    Highly sophisticated quantum chemistry techniques have been employed to build a three-state diabatic Hamiltonian for the nitrate radical (NO_3). Eigenvalues of this Hamiltonian (which includes effects beyond the Born-Oppenheimer approximation) are consistent with the known ``vibrational'' levels of NO_3 up to ca. 2100 cm-1 above the zero-point level; with a small empirical adjustment of the diabatic coupling strength, calculated levels are within 20 cm-1 of the measured level positions for those that have been observed experimentally. Of the eleven states with e' symmetry calculated below 2000 cm-1, nine of these have been observed either in the gas phase by Hirota and collaborators as well as Neumark and Johnston, or in frozen argon by Jacox. However, the Hamiltonian produces two levels that have not been seen experimentally: one calculated to lie at 1075 cm-1 (which is the third e' state, above ν_4 and 2ν_4) and another at 1640 cm-1 which is best assigned as one of the two e' sublevels of 4ν_4. A significant result is that the state predicted at 1075 cm-1 is not far enough above the predicted 2ν_4 level (777 cm-1 v. ca. 760 cm-1 from experiment) to be plausibly assigned as 3ν_4 (which is at 1155 cm-1: experimental position: 1173 cm-1), nor is its nodal structure consistent with such an idea. Rather, it is quite unambiguously the ν_3 level. Given the fidelity of the results generated by this model Hamiltonian as compared to experiment, it can safely be concluded that the prominent infrared band seen at 1492 cm-1 (corresponding to a calculated level at 1500 cm-1) is not ν_3, but rather a multiquantum state best viewed as a sublevel of the ν_3 + ν_4 combination.

  11. The spatio-temporal variability of groundwater depth in a typical desert-oasis ecotone

    NASA Astrophysics Data System (ADS)

    Wang, Guohua; Zhao, Wenzhi

    2015-06-01

    Eight groundwater observation wells were installed along the river plain, where the landscapes varied from floodplain, to oasis farmland, to desert-oasis ecotone to desert, in a typical desert-oasis ecotone in northwestern China. Ten years of data were used to analyze temporal and spatial changes in the groundwater depth. The results indicated that in the last decade: (1) the groundwater depths in the floodplain (GW1) and the desert (GW8) were basically stable; (2) the groundwater depths in the oasis farmland (GW2, GW3, GW4) increased dramatically: the annual fluctuations were 1.43, 1.01 and 0.79 m respectively, with the groundwater depths increasing by 0.13-0.18 m every year; (3) the groundwater depths in the desert-oasis ecotone (GW5, GW6, GW7) also increased dramatically: the annual fluctuations were 1.10, 1.06 and 1.05 m respectively, and the depths increased by 0.10-0.15 m every year; (4) the influence distance between the river and both the farmland and the desert-oasis ecotone was about 1000-2000 m in the study area. These results show that the natural seasonal fluctuation influence on groundwater depths was not significant, but the human-induced fluctuations such as intensive irrigation caused a significant increase in groundwater depth in both the farmland and the desert-oasis ecotone, seriously affecting sustainable agriculture development and the environment, in the oasis.

  12. Effects of Tillage and Sampling Depth on the Distribution of Phosphorus and Nitrogen Forms in Manure Applied Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estimating N and P forms in environmental and agricultural soils can be influenced by tillage practices and sampling depths. Historically, soil sampling depth used to estimate nutrients is about 15 cm because most plant roots grow to that depth. Under conventional tillage (CT) nutrients are mixed in...

  13. Rotating drum variable depth sampler

    DOEpatents

    Nance, Thomas A.; Steeper, Timothy J.

    2008-07-01

    A sampling device for collecting depth-specific samples in silt, sludge and granular media has three chambers separated by a pair of iris valves. Rotation of the middle chamber closes the valves and isolates a sample in a middle chamber.

  14. Perceived depth from shading boundaries.

    PubMed

    Kim, Juno; Anstis, Stuart

    2016-01-01

    Shading is well known to provide information the visual system uses to recover the three-dimensional shape of objects. We examined conditions under which patterns in shading promote the experience of a change in depth at contour boundaries, rather than a change in reflectance. In Experiment 1, we used image manipulation to illuminate different regions of a smooth surface from different directions. This manipulation imposed local differences in shading direction across edge contours (delta shading). We found that increasing the angle of delta shading, from 0° to 180°, monotonically increased perceived depth across the edge. Experiment 2 found that the perceptual splitting of shading into separate foreground and background surfaces depended on an assumed light source from above prior. Image regions perceived as foreground structures in upright images appeared farther in depth when the same images were inverted. We also found that the experienced break in surface continuity could promote the experience of amodal completion of colored contours that were ambiguous as to their depth order (Experiment 3). These findings suggest that the visual system can identify occlusion relationships based on monocular variations in local shading direction, but interprets this information according to a light source from above prior of midlevel visual processing. PMID:27271807

  15. Structural and magnetic properties with large reversible magnetocaloric effect in (La1-xPrx)0.85Ag0.15MnO3 (0.0 ≤ x ≤ 0.5) compounds

    NASA Astrophysics Data System (ADS)

    Osman Ayaş, Ali; Akyol, Mustafa; Ekicibil, Ahmet

    2016-04-01

    We report on the effect of Pr doping on structural, magnetic and magnetocaloric properties in (La1-xPrx)0.85Ag0.15MnO3 (0.0 ≤ x ≤ 0.5) compounds. The main crystal structure has been studied by performing X-ray diffraction method and structural analysis based on Rietveld method where it is found that although samples at low concentration level (x ≤ 0.2) have rhombohedral phase ?, others (x ≥ 0.3) have orthorhombic (Pbnm) phase. Scanning electron microscope images show that the average particle size decreases by increasing Pr amount in the main structure. It is observed that the second-order transition temperature from ferromagnetic to paramagnetic phase is dramatically decreased from 262 to 138 K by increasing Pr concentration in (La1-xPrx)0.85Ag0.15MnO3. On the other hand, all samples have also antiferromagnetic coupling observed below TN ~ 50 K. The maximum magnetic entropy change (-ΔSM)max and relative cooling power values were found in the range of 7.90-2.88 J/kg K and 213.32-153.50 J/kg, respectively, under 50 kOe field change in our samples. It can be argued that particularly the compounds LPAM with x = 0.0, 0.1 and 0.2 are expected to be promising candidate for magnetic refrigeration.

  16. Sub-10 μm grain size, Ba1-xCaxTi0.9Zr0.1O3 (x = 0.10 and x = 0.15) piezoceramics processed using a reduced thermal treatment

    NASA Astrophysics Data System (ADS)

    Reyes-Montero, A.; Pardo, L.; López-Juárez, R.; González, A. M.; Rea-López, S. O.; Cruz, M. P.; Villafuerte-Castrejón, M. E.

    2015-06-01

    The solid-state synthesis of Ba1-xCaxTi0.9Zr0.1O3 (x = 0.10, 0.15) (BCTZ) powder and the processing method of ceramics, by the use of reduced synthesis time and temperature (1250 °C for 2 h), are reported. Homogeneous and dense (≥95%) ceramic microstructures with sub-10 μm grain size were obtained under all sintering conditions. A comparative study of their ferro-piezoelectric properties as a function of sintering temperatures is presented. The study shows the role of the grain size effect for improving both piezoelectric and ferroelectric properties of these materials. With an increase of the sintering temperature, grain growth was promoted; therefore, higher ferro-piezoelectric values were obtained (at 1400 °C, for x = 0.10: d33 = 300 pC/N, {{d}31}=-150 pC/N, kp = 48% for x = 0.15: d33 = 410 pC/N, d31 =-154 pC/N, kp = 50%). In addition, a diffuse phase transition is observed in these BCTZ ceramics with a Curie temperature near 100 °C at 1 kHz.

  17. Investigation of the effect of Ag addition on the critical current density of the high-temperature superconductor Nd1.85Ce0.15CuO4

    NASA Astrophysics Data System (ADS)

    Radhikesh Raveendran, N.; Vinod, K.; Amaladass, E. P.; Janaki, J.; Mani, Awadhesh

    2016-07-01

    We have synthesized a Nd1.85Ce0.15CuO4 + Ag composite system with the aim of studying the effect of Ag addition in the electron-doped system Nd1.85Ce0.15CuO4 on its superconducting and magnetic properties. Measurements of magnetization using a vibration sample magnetometer indicate a systematic increase in diamagnetic shielding upon Ag addition. A subsequent analysis of the critical current density using the Bean model indicates a small but significant increase in intra-grain critical current density upon Ag addition. From the study of the dependence of electrical resistivity on the temperature and electrical current, an increase in inter-granular critical current has also been evidenced upon Ag addition. These results correlate well with the earlier reports of a similar improvement in the properties on the hole-doped ceramic superconductor/Ag composites. Possible reasons for the enhancement of JC have been described and discussed. Magnetic characterization by AC susceptibility using a SQUID magnetometer has been presented for a representative composition, which enabled delineation of the inter- and intra-granular transitions.

  18. Magneto-transport properties of La0.75Ca0.15Sr0.1MnO3 with YBa2Cu3O7-δ addition

    NASA Astrophysics Data System (ADS)

    Zghal, E.; Koubaa, M.; Berthet, P.; Sicard, L.; Cheikhrouhou-Koubaa, W.; Decorse-Pascanut, C.; Cheikhrouhou, A.; Ammar-Merah, S.

    2016-09-01

    We report the structural, magnetic, electrical and magentoresistance properties of (La0.75Ca0.15Sr0.1MnO3)1-x(YBa2Cu3O7-δ)x (with x=0, 0.025, 0.05, 0.075, 0.1, 0.2, and 0.3) composites synthesized through sol-gel method. The powder X-ray diffraction patterns indicate no evidence of reaction between La0.75Ca0.15Sr0.1MnO3 (LCSMO) and YBa2Cu3O7-δ (YBCO). The addition of YBCO induces a reduction of the total magnetization while the Curie temperature remains almost constant (∼312 K). The behavior of the electrical resistivity evolves differently depending on the doping level. Above the paramagnetic-insulating transition temperature the resistivity data were best-fitted by using the adiabatic small polaron and variable range hopping models. Ferromagnetic-metallic regime in the composites seems to emanate from the electron-phonon or/and electron-magnon scattering processes. With increasing the YBCO doping content (until x=0.1), the positive magnetoresistance (MR) of YBCO phase dominates the negative MR of LCSMO one, which gives rise to the decreasing of MR of the composites.

  19. Power and capacity fade mechanism of LiNi0.8Co0.15Al0.0502composite cathodes in high-power lithium-ion batteries

    SciTech Connect

    Kostecki, Robert; McLarnon, Frank

    2003-09-01

    High-power Li-ion cells that were tested at elevatedtemperatures showed a significant impedance rise, which was associatedprimarily with the LiNi0.8Co0.15Al0.05O2 cathode. By systematicallycollecting thousands of Raman spectra from 50 x 80 mm areas at 0.9 mmspatial resolution, and integrating the respective bands of the cathodecomponents for each spectrum, we were able to produce color-coded,semi-quantitative composition maps of cathode surfaces. Raman microscopyimages of cathodes from tested cells revealed that cell cycling orstorage at elevated temperatures led to significant changes in theLiNi0.8Co0.15Al0.05O2/elemental-carbon surface concentration ratio. Theloss of conductive carbon correlated with the power and capacity fade ofthe tested cathodes. The cathode surface state of charge (SOC) variedbetween individual grains of active material, and at some locations thespectra indicated the presence of fully charged material, despite thedeep cell discharge at the end of testing.

  20. Rare-earth energy levels in Nd2CuO4, Pr2CuO4, and the electron superconductor Pr1.85Ce0.15CuO4

    NASA Astrophysics Data System (ADS)

    Loong, C.-K.; Soderholm, L.

    1993-11-01

    The magnetic excitation spectra of the electron superconductor Pr1.85Ce0.15CuO4 and related parent compounds Pr2CuO4 and Nd2CuO4 have been determined by inelastic neutron scattering. We observe crystal-field transitions up to about 100 meV within the Pr3+ 3H4 and Nd3+ 4I9/2 Russell-Saunders ground multiplets in these materials. We find that a crystal-field treatment of the Pr3+ and Nd3+ ions can adequately explain the observed excitation spectra for both Pr2CuO4 and Nd2CuO4. The obtained crystal-field parameters are close to values estimated from a superposition-model calculation and Mössbauer data. The Pr3+ and Nd3+ wave functions are found to have significant (~=20%) admixture of some states belonging to higher J multiplets. The calculated contributions to the susceptibility of Pr2CuO4 and Nd2CuO4 from the crystal-field states agree well with experiments. The observed crystal-field transitions in the superconductor Pr1.85Ce0.15CuO4 shift to slightly lower energies and are broadened significantly relative to the present compound due to chemical disorder from Ce doping.

  1. "The 5 cm Rule": Biopower, Sexuality and Schooling

    ERIC Educational Resources Information Center

    Allen, Louisa

    2009-01-01

    This paper explores "the 5 cm rule", a regulation around student contact discovered during an investigation of the sexual culture of schooling with 16-19-year-olds in New Zealand. Implemented to stem "inappropriate and unwanted" touching, it stipulates that students must maintain a physical distance of 5 cm at all times. It is argued this rule…

  2. Design and Performance of 40 cm Ion Optics

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2001-01-01

    A 40 cm ion thruster is being developed at the NASA Glenn Research Center to obtain input power and propellant throughput capabilities of 10 kW and 550 kg. respectively. The technical approach here is a continuation of the "derating" technique used for the NSTAR ion thruster. The 40 cm ion thruster presently utilizes the NSTAR ion optics aperture geometry to take advantage of the large database of lifetime and performance data already available. Dome-shaped grids were chosen for the design of the 40 cm ion optics because this design is naturally suited for large-area ion optics. Ion extraction capabilities and electron backstreaming limits for the 40 cm ion optics were estimated by utilizing NSTAR 30 cm ion optics data. A preliminary service life assessment showed that the propellant throughput goal of 550 kg of xenon may be possible with molybdenum 40 cm ion optics. One 40 cm ion optics' set has been successfully fabricated to date. Additional ion optics' sets are presently being fabricated. Preliminary performance tests were conducted on a laboratory model 40 cm ion thruster.

  3. Photofraction of a 5 cm x 2 cm BGO scintillator. [bismuth germanate crystal for use in cosmic gamma ray detector

    NASA Technical Reports Server (NTRS)

    Dunphy, P. P.; Forrest, D. J.

    1985-01-01

    The photofraction of a 5.1 cm x 2.0 cm bismuth germanate (BGO) scintillator was measured over a gamma-ray energy range of 0.2 to 6.1 MeV. Several methods, used to minimize the effect of room scattering on the measurement, are discussed. These include a gamma-gamma coincidence technique, a beta-gamma coincidence technique, and the use of sources calibrated with a standard 7.6 cm x 7.6 cm sodium iodide scintillator.

  4. Depth dependence determination of the wedge transmission factor for 4--10 MV photon beams

    SciTech Connect

    McCullough, E.C.; Gortney, J.; Blackwell, C.R.

    1988-07-01

    The depth dependence (up to 25 cm) of the in-phantom wedge transmission factor (WTF) has been determined for three medical linear accelerator x-ray beams with energies of 4, 6, and 10 MV containing 15/sup 0/--60/sup 0/ (nominal) brass wedges. All measurements were made with a cylindrical ionization chamber in water, for a field size of 10 x 10 cm/sup 2/ with a source--skin distance of 80 or 100 cm. We conclude that, for the accelerators studied, the WTF factor at depth is less than 2% different from that determined at d/sub max/ (for the nominal wedge angles and photon energies studied) unless the depth of interest is greater than 10 cm. Up to the maximum depth studied (25 cm) the relative wedge factor: that is, wedge factor at depth compared to that determined at d/sub max/ : was about equal to or less than 1.02 for the 15/sup 0/ and 30/sup 0/ wedges and any of the photon beam energies studied. For the seldom utilized combination of a nominal wedge angle in excess of 45/sup 0/ with a depth greater than 10 cm, the WTF at depth can differ from the WTF determined at d/sub max/, by up to 5%. Since the wedge transmission factor is reflective of relative percent dose data, our results also indicate that it is in error to use open field percent depth doses for certain combinations of wedge angle, photon energy, and depth.

  5. Photon counting compressive depth mapping.

    PubMed

    Howland, Gregory A; Lum, Daniel J; Ware, Matthew R; Howell, John C

    2013-10-01

    We demonstrate a compressed sensing, photon counting lidar system based on the single-pixel camera. Our technique recovers both depth and intensity maps from a single under-sampled set of incoherent, linear projections of a scene of interest at ultra-low light levels around 0.5 picowatts. Only two-dimensional reconstructions are required to image a three-dimensional scene. We demonstrate intensity imaging and depth mapping at 256 × 256 pixel transverse resolution with acquisition times as short as 3 seconds. We also show novelty filtering, reconstructing only the difference between two instances of a scene. Finally, we acquire 32 × 32 pixel real-time video for three-dimensional object tracking at 14 frames-per-second. PMID:24104293

  6. Ultrasonic material hardness depth measurement

    DOEpatents

    Good, M.S.; Schuster, G.J.; Skorpik, J.R.

    1997-07-08

    The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part. 12 figs.

  7. Ultrasonic material hardness depth measurement

    DOEpatents

    Good, Morris S.; Schuster, George J.; Skorpik, James R.

    1997-01-01

    The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part.

  8. A practical block detector for a depth encoding PET camera

    SciTech Connect

    Rogers, J.G.; Moisan, C.; Hoskinson, E.M.; Andreaco, M.S.; Williams, C.W.; Nutt, A.

    1995-10-01

    The depth-of-interaction effect in block detectors degrades the image resolution in commercial PET cameras and impedes the natural evolution of smaller, less expensive cameras. A method for correcting the measured position of each detected gamma ray by measuring its depth-of-interaction was tested and found to recover 38% of the lost resolution in a table-top 50 cm diameter camera. To obtain the desired depth sensitivity, standard commercial detectors were modified by a simple and practical process, which is suitable for mass production of the detectors. The impact of the detector modifications on central image resolution and on the ability of the camera to correct for object scatter were also measured.

  9. Radioactivities vs. depth in Apollo 16 and 17 soil

    NASA Technical Reports Server (NTRS)

    Fireman, E. L.; D'Amico, J.; Defelice, J.

    1973-01-01

    The radioactivities of Ar-37, Ar-39, and H-3 measured at a number of depths for Apollo 16 and 17 soil are reported. The Ar-37 activities vs depth in the Apollo 16 drill string increased with depth and reached a broad maximum in the neighborhood of 50 g per sq cm before decreasing. The Ar-39 activities in Apollo 17 soil were higher than in Apollo 16 soil, probably owing to the higher Fe and Ti contents. The H-3 activities in Apollo 16 and 17 soil were quite similar and indicate that the 4 August 1972 flare produced very little H-3 compared to the amount produced by solar flares during the previous 50 years.

  10. Titan's surface properties inferred from the seasonal brightness variation at 2-cm wavelength

    NASA Astrophysics Data System (ADS)

    Janssen, M.; Le Gall, A.; Lopes, R.; Lorenz, R.; Malaska, M.; Neish, C.; Solomonidou, A.

    2015-10-01

    A comprehensive calibration and mapping of the thermal microwave emission from Titan's surface at 2.2-cm wavelength has been completed by the passive radiometer included in the Cassini RADAR instrument. A seasonal brightness temperature variation has been determined that is comparable to but slightly smaller than that obtained by Cassini's Composite Infrared Spectrometer (CIRS). This difference has implications for the composition and structure of Titan's surface; namely, that most of Titan's surface is covered by the deposition and possible redistribution of tholin-like atmospheric photochemical products to a depth of at least a meter.

  11. Underwater camera with depth measurement

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Lin, Keng-Ren; Tsui, Chi L.; Schipf, David; Leang, Jonathan

    2016-04-01

    The objective of this study is to develop an RGB-D (video + depth) camera that provides three-dimensional image data for use in the haptic feedback of a robotic underwater ordnance recovery system. Two camera systems were developed and studied. The first depth camera relies on structured light (as used by the Microsoft Kinect), where the displacement of an object is determined by variations of the geometry of a projected pattern. The other camera system is based on a Time of Flight (ToF) depth camera. The results of the structural light camera system shows that the camera system requires a stronger light source with a similar operating wavelength and bandwidth to achieve a desirable working distance in water. This approach might not be robust enough for our proposed underwater RGB-D camera system, as it will require a complete re-design of the light source component. The ToF camera system instead, allows an arbitrary placement of light source and camera. The intensity output of the broadband LED light source in the ToF camera system can be increased by putting them into an array configuration and the LEDs can be modulated comfortably with any waveform and frequencies required by the ToF camera. In this paper, both camera were evaluated and experiments were conducted to demonstrate the versatility of the ToF camera.

  12. [Pharmacological effects of CM6912 and its main metabolites].

    PubMed

    Morishita, H; Kushiku, K; Furukawa, T; Yamaki, Y; Izawa, M; Shibazaki, Y; Shibata, U

    1985-07-01

    Pharmacodynamic effects of ethyl 7-chloro-2,3-dihydro-5-(2-fluorophenyl)-2-oxo-1H-1,4- benzodiazepine-3-carboxylate (CM6912), a new benzodiazepine derivative, and its main metabolites (CM6913 = M1, CM7116 = M2) on the peripheral systems were investigated in several species of animals. In pentobarbital-anesthetized rabbits, CM6912 and M2 (1 or 5 mg/kg, i.v.) had little effect on blood pressure, heart rate and ECG, but it slightly reduced the respiration rate. M1 decreased the heart rate without affecting respiration, blood pressure and ECG. In conscious rabbits, CM6912 and M2 (1 mg/kg, i.v.) did not affect respiration, blood pressure, heart rate and ECG, but M1 (1 mg/kg, i.v.) increased the heart rate. CM6912 (5 or 30 mg/kg), when administered orally, also increased heart rate. In pentobarbital-anesthetized dogs, CM6912 and its metabolites (5 mg/kg, i.v.) decreased respiration and heart rate without affecting blood pressure and ECG. CM 6912 (5 mg/kg, i.v.) did not affect cardiovascular responses to the carotid occlusion, vagus stimulation, and pre- and post-ganglionic stimulation of cardiac ganglion in anesthetized dogs. CM6912 and its metabolites affected neither the spontaneous contraction nor the heart rate of isolated rabbit atria. These compounds also had no action on isolated aortic strips from rabbits. CM6912 and its metabolites did not affect the muscle tone of isolated guinea pig intestine, and it had no effects on the contractile responses to acetylcholine, histamine, serotonin and barium chloride. In isolated rabbit intestine, CM6912 and M2 slightly reduced the amplitude of contraction, while M1 had no effect. CM6912 and its metabolites did not affect the spontaneous motility of isolated non-pregnant and pregnant rat uteri as well as in situ non-pregnant rat uterus and isolated guinea pig vas deferens, including the contractile response to adrenaline. CM6912 and M2 relaxed isolated guinea pig trachea strips only at high concentrations. CM6912 and its

  13. 21 cm absorption by compact hydrogen discs around black holes in radio-loud nuclei of galaxies

    SciTech Connect

    Loeb, Abraham

    2008-05-15

    The clumpy maser discs observed in some galactic nuclei mark the outskirts of the accretion disc that fuels the central black hole and provide a potential site of nuclear star formation. Unfortunately, most of the gas in maser discs is currently not being probed; large maser gains favor paths that are characterized by a small velocity gradient and require rare edge-on orientations of the disc. Here we propose a method for mapping the atomic hydrogen distribution in nuclear discs through its 21 cm absorption against the radio continuum glow around the central black hole. In NGC 4258, the 21 cm optical depth may approach unity for high angular resolution (VLBI) imaging of coherent clumps which are dominated by thermal broadening and have the column density inferred from x-ray absorption data, {approx}10{sup 23} cm{sup -2}. Spreading the 21 cm absorption over the full rotation velocity width of the material in front of the narrow radio jets gives a mean optical depth of {approx}0.1. Spectroscopic searches for the 21 cm absorption feature in other galaxies can be used to identify the large population of inclined gaseous discs which are not masing in our direction. Follow-up imaging of 21 cm silhouettes of accelerating clumps within these discs can in turn be used to measure cosmological distances.

  14. Evaluation of CM5 Charges for Condensed-Phase Modeling.

    PubMed

    Vilseck, Jonah Z; Tirado-Rives, Julian; Jorgensen, William L

    2014-07-01

    The recently developed Charge Model 5 (CM5) is tested for its utility in condensed-phase simulations. The CM5 approach, which derives partial atomic charges from Hirshfeld population analyses, provides excellent results for gas-phase dipole moments and is applicable to all elements of the periodic table. Herein, the adequacy of scaled CM5 charges for use in modeling aqueous solutions has been evaluated by computing free energies of hydration (ΔG hyd) for 42 neutral organic molecules via Monte Carlo statistical mechanics. An optimal scaling factor for the CM5 charges was determined to be 1.27, resulting in a mean unsigned error (MUE) of 1.1 kcal/mol for the free energies of hydration. Testing for an additional 20 molecules gave an MUE of 1.3 kcal/mol. The high precision of the results is confirmed by free energy calculations using both sequential perturbations and complete molecular annihilation. Performance for specific functional groups is discussed; sulfur-containing molecules yield the largest errors. In addition, the scaling factor of 1.27 is shown to be appropriate for CM5 charges derived from a variety of density functional methods and basis sets. Though the average errors from the 1.27*CM5 results are only slightly lower than those using 1.14*CM1A charges, the broader applicability and easier access to CM5 charges via the Gaussian program are additional attractive features. The 1.27*CM5 charge model can be used for an enormous variety of applications in conjunction with many fixed-charge force fields and molecular modeling programs. PMID:25061445

  15. Value of the bipolar lead CM5 in electrocardiography.

    PubMed

    Quyyumi, A A; Crake, T; Mockus, L J; Wright, C A; Rickards, A F; Fox, K M

    1986-10-01

    Only bipolar lead recording are available during ambulatory monitoring. Their sensitivity in detecting ST segment changes in relation to standard electrocardiographic leads is not known. The magnitude and direction of ST segment changes in the bipolar lead CM5 were compared with those in standard electrocardiographic leads in patients during exercise testing and percutaneous transluminal coronary angioplasty. Thirty patients with coronary artery disease were studied during exercise tests in which ST segment depression (greater than 0.5 mm) occurred in one or more standard electrocardiographic leads and 13 patients were studied during angioplasty that resulted in ST segment change in one or more leads (I, II, III, V2, V5, and CM5). Lead CM5 was the most sensitive lead (93%) during exercise testing and also showed the greatest magnitude of ST segment change below the isoelectric line in 93% of the patients. Only two patients, one with ST segment elevation in inferior leads and one with changes restricted to septal leads, had no ST segment depression in lead CM5. When ST segment shift from the baseline electrocardiogram was measured the magnitude of depression was greatest in lead CM5 in only 63% of the patients. During angioplasty of the left anterior descending coronary artery, lead CM5 showed ST segment depression in seven patients, ST segment elevation in two, and a biphasic response in one. Two of the three patients with balloon inflation in right coronary artery developed ST segment elevation in lead CM5. Thus lead CM5 is a reliable lead for detecting subendocardial ischaemia experienced during everyday activities in anginal patients. During total occlusion of coronary arteries (as in variant angina or myocardial infarction) lead CM5 commonly shows ST segment depression and changes due to right coronary artery occlusion may not be detected. PMID:3768217

  16. Value of the bipolar lead CM5 in electrocardiography.

    PubMed Central

    Quyyumi, A A; Crake, T; Mockus, L J; Wright, C A; Rickards, A F; Fox, K M

    1986-01-01

    Only bipolar lead recording are available during ambulatory monitoring. Their sensitivity in detecting ST segment changes in relation to standard electrocardiographic leads is not known. The magnitude and direction of ST segment changes in the bipolar lead CM5 were compared with those in standard electrocardiographic leads in patients during exercise testing and percutaneous transluminal coronary angioplasty. Thirty patients with coronary artery disease were studied during exercise tests in which ST segment depression (greater than 0.5 mm) occurred in one or more standard electrocardiographic leads and 13 patients were studied during angioplasty that resulted in ST segment change in one or more leads (I, II, III, V2, V5, and CM5). Lead CM5 was the most sensitive lead (93%) during exercise testing and also showed the greatest magnitude of ST segment change below the isoelectric line in 93% of the patients. Only two patients, one with ST segment elevation in inferior leads and one with changes restricted to septal leads, had no ST segment depression in lead CM5. When ST segment shift from the baseline electrocardiogram was measured the magnitude of depression was greatest in lead CM5 in only 63% of the patients. During angioplasty of the left anterior descending coronary artery, lead CM5 showed ST segment depression in seven patients, ST segment elevation in two, and a biphasic response in one. Two of the three patients with balloon inflation in right coronary artery developed ST segment elevation in lead CM5. Thus lead CM5 is a reliable lead for detecting subendocardial ischaemia experienced during everyday activities in anginal patients. During total occlusion of coronary arteries (as in variant angina or myocardial infarction) lead CM5 commonly shows ST segment depression and changes due to right coronary artery occlusion may not be detected. PMID:3768217

  17. Evaluation of CM5 Charges for Condensed-Phase Modeling

    PubMed Central

    2015-01-01

    The recently developed Charge Model 5 (CM5) is tested for its utility in condensed-phase simulations. The CM5 approach, which derives partial atomic charges from Hirshfeld population analyses, provides excellent results for gas-phase dipole moments and is applicable to all elements of the periodic table. Herein, the adequacy of scaled CM5 charges for use in modeling aqueous solutions has been evaluated by computing free energies of hydration (ΔGhyd) for 42 neutral organic molecules via Monte Carlo statistical mechanics. An optimal scaling factor for the CM5 charges was determined to be 1.27, resulting in a mean unsigned error (MUE) of 1.1 kcal/mol for the free energies of hydration. Testing for an additional 20 molecules gave an MUE of 1.3 kcal/mol. The high precision of the results is confirmed by free energy calculations using both sequential perturbations and complete molecular annihilation. Performance for specific functional groups is discussed; sulfur-containing molecules yield the largest errors. In addition, the scaling factor of 1.27 is shown to be appropriate for CM5 charges derived from a variety of density functional methods and basis sets. Though the average errors from the 1.27*CM5 results are only slightly lower than those using 1.14*CM1A charges, the broader applicability and easier access to CM5 charges via the Gaussian program are additional attractive features. The 1.27*CM5 charge model can be used for an enormous variety of applications in conjunction with many fixed-charge force fields and molecular modeling programs. PMID:25061445

  18. Eight-cm mercury ion thruster system technology

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technology status of 8 cm diameter electron bombardment ion thrusters is presented. Much of the technology resulting from the 5 cm diameter thruster has been adapted and improved upon to increase the reliability, durability, and efficiency of the 8 cm thruster. Technology discussed includes: dependence of neutralizer tip erosion upon neutralizer flow rate; impregnated and rolled-foil insert cathode performance and life testing; neutralizer position studies; thruster ion beam profile measurements; high voltage pulse ignition; high utilization ion machined accelerator grids; deposition internal and external to the thruster; thruster vectoring systems; thruster cycling life testing and thruster system weights for typical mission applications.

  19. Ion accelerator systems for high power 30 cm thruster operation

    NASA Technical Reports Server (NTRS)

    Aston, G.

    1982-01-01

    Two and three-grid accelerator systems for high power ion thruster operation were investigated. Two-grid translation tests show that over compensation of the 30 cm thruster SHAG grid set spacing the 30 cm thruster radial plasma density variation and by incorporating grid compensation only sufficient to maintain grid hole axial alignment, it is shown that beam current gains as large as 50% can be realized. Three-grid translation tests performed with a simulated 30 cm thruster discharge chamber show that substantial beamlet steering can be reliably affected by decelerator grid translation only, at net-to-total voltage ratios as low as 0.05.

  20. [Quantitative determination of the depth of edge influence on soil moisture in pepper-forest boundary of Minjiang River upper reaches].

    PubMed

    Li, Liguang; He, Xingyuan; Li, Xiuzhen; Wen, Qingchun

    2006-11-01

    A typical pepper-forest boundary was selected in the arid valley of Minjiang River upper reaches, and the moisture content in 0-15 cm soil layer was determined by time-domain reflectometry (TDR) during drought, after rain, and different seasons. Moving split-window techniques (MSWT) was employed to detect the depth of edge influence (DEI) on soil moisture and its dynamic variation with time. The results showed that the changes of squared Euclidean distance (SED) curve on the graph tended to become stable when the window width reached 8 - 12, and DEI could be detected. The seasonal variation of soil moisture could be divided into three periods, i.e., rising period (January to April), peak period (May to October), and lessen period (November to December). DEI was smaller during drought, and increased after rain. The DEI on soil moisture ranged from 6 m in pepper field to 2 m in forest during drought and from 12 m in pepper field to 2 m in forest after rain, but ranged from 10 m in pepper field to 2 m in forest field within a year. DEI was different in different seasons, and was dynamic. Under such condition of soil moisture, the forest restoration from pepper land and the seedling planting were not ecologically reasonable. Reducing human disturbance and revegetating with natural shrubs and meadows could be more effective for vegetation conservation in the arid valley of Minjiang River upper reaches. PMID:17269317

  1. Substrate effect on in-plane dielectric and microwave properties of Ba(Sn{sub 0.15}Ti{sub 0.85})O{sub 3} thin films

    SciTech Connect

    Song, S.N.; Zhai, J.W. Yao, X.

    2008-08-04

    The microstructure and in-plane dielectric and microwave properties of Barium tin titanate Ba(Sn{sub 0.15}Ti{sub 0.85})O{sub 3} (BTS) thin films grown on (1 0 0) LaAlO{sub 3} and (1 0 0) MgO single-crystal substrates through sol-gel process were investigated. X-ray diffraction and field emission scanning electron microscopy were used to characterize crystal structure of phases and microstructure of the thin films, respectively. Microwave properties of the films were measured from 1 to 10 GHz by the interdigital capacitor configuration. The obvious differences in the dielectric and microwave properties are attributed to the stress in the films, which result from the lattice mismatch and difference in the thermal expansion coefficients between the film and substrates. This work clearly reveals the highly promising potential of BTS films for application in tunable microwave devices.

  2. The atomic structure and chemistry of Fe-rich steps on antiphase boundaries in Ti-doped Bi{sub 0.9}Nd{sub 0.15}FeO{sub 3}

    SciTech Connect

    MacLaren, Ian Craven, Alan J.; Schaffer, Bernhard; Wang, LiQiu; Ramasse, Quentin M.; Kalantari, Kambiz; Reaney, Ian M.

    2014-06-01

    Stepped antiphase boundaries are frequently observed in Ti-doped Bi{sub 0.85}Nd{sub 0.15}FeO{sub 3}, related to the novel planar antiphase boundaries reported recently. The atomic structure and chemistry of these steps are determined by a combination of high angle annular dark field and bright field scanning transmission electron microscopy imaging, together with electron energy loss spectroscopy. The core of these steps is found to consist of 4 edge-sharing FeO{sub 6} octahedra. The structure is confirmed by image simulations using a frozen phonon multislice approach. The steps are also found to be negatively charged and, like the planar boundaries studied previously, result in polarisation of the surrounding perovskite matrix.

  3. Influence of electrode preparation on the electrochemical performance of LiNi0.8Co0.15Al0.05O2 composite electrodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Tran, Hai Yen; Greco, Giorgia; Täubert, Corina; Wohlfahrt-Mehrens, Margret; Haselrieder, Wolfgang; Kwade, Arno

    2012-07-01

    The electrode manufacturing for lithium-ion batteries is based on a complex process chain with several influencing factors. A proper tailoring of the electrodes can greatly improve both the electrochemical performances and the energy density of the battery. In the present work, some significant parameters during the preparation of LiNi0.8Co0.15Al0.05O2-based cathodes were investigated. The active material was mixed with a PVDF-binder and two conductive additives in different ratios. The electrode thickness, the degree of compacting and the conductive agent type and mixing ratio have proven to have a strong impact on the electrochemical performances of the composite electrodes, especially on their behaviour at high C-rates. Further it has been shown that the compacting has an essential influence on the mechanical properties of NCA coatings, according to their total, ductile and elastic deformation behaviour.

  4. Synthesis, magnetic properties and magnetostriction of Pr(Fe0.75Co0.15Cu0.01Nb0.04B0.05)1.93 bulk nanocrystalline synthesized under high pressure

    NASA Astrophysics Data System (ADS)

    Hu, Cheng-Chao; Shi, Yang-Guang; Shi, Da-Ning; Chen, Long-Qing

    2016-05-01

    Bulk nanocrystalline Pr(Fe0.75Co0.15Cu0.01Nb0.04B0.05)1.93 alloys were synthesized by annealing its melt-spinning ribbons under different pressures and temperatures. It was demonstrated that the average grain size decreases with increasing pressure from 3 GPa to 6 GPa under the same annealing temperature of 853 K but increases with increasing temperature from 823 K to 923 K under the same annealing pressure of 6 GPa. A negative correlation between the coercivity and average grain size was found in the present investigated system. Grain refinement without losing the advantage of volume fraction of magnetostrictive phase offers the sample annealed under 6 GPa and 853 K the optimized magnetostrictive property, which might make it potential material for magnetostrictive application.

  5. Superconducting properties of single crystalline FeTe1-xSex (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50)

    NASA Astrophysics Data System (ADS)

    Sudesh; Kumar, R.; Varma, G. D.

    2015-06-01

    In this paper we have grown single crystalline samples of Se-doped FeTe compound using self-flux technique and studied the structural and electrical transport properties of the as-grown crystals. The samples have been grown with compositions FeTe1-xSex (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50). The as-grown samples are then investigated for their structural and superconducting properties by means of X-ray diffraction and physical property measurements. The XRD results of powdered samples reveal a single (tetragonal) phase with space group symmetry P4/nmm for all the samples. The lattice parameters are observed to reduce with increase of Se-doping at Te-site. Highest Hc2(0) (˜180 T) value has been observed for FeTe0.5Se0.5 sample.

  6. Superspin glassy behaviour of La{sub 0.7}Ca{sub 0.3}Mn{sub 0.85}Al{sub 0.15}O{sub 3} thin film

    SciTech Connect

    Kumar, Manish; Choudhary, R. J. Shukla, D. K.; Phase, D. M.

    2014-07-21

    Here, we present the low temperature magnetic behaviour of epitaxial La{sub 0.7}Ca{sub 0.3}Mn{sub 0.85}Al{sub 0.15}O{sub 3} (LCMAO) thin film through a series of DC magnetic measurements. Overall behaviour inferred from the magnetization measurements indicate that the magnetic phases created due to Al doping induced inhomogeneous distribution of Mn{sup 3+} and Mn{sup 4+} ions and oxygen vacancies present in the system act like superspins, and the strong interaction among themselves results in the superspin glassy behaviour. Interactions among the superspins are marked by the aging and zero filed memory effects. The glassy magnetic phase in LCMAO is found to follow the hierarchical model of spin glasses.

  7. First laser emission of Yb0.15:(Lu0.5Y0.5)3Al5O12 ceramics.

    PubMed

    Toci, Guido; Pirri, Angela; Li, Jiang; Xie, Tengfei; Pan, Yubai; Babin, Vladimir; Beitlerova, Alena; Nikl, Martin; Vannini, Matteo

    2016-05-01

    We report the first laser oscillation on Yb0.15:(Lu0.5Y0.5)3Al12 ceramics at room temperature. At 1030 nm we measured a maximum output power of 7.3 W with a corresponding slope efficiency of 55.4% by using an output coupler with a transmission of T = 39.2%. The spectroscopic properties are compared with those of the two parent garnets Yb:YAG and Yb:LuAG. To the best of our knowledge these are the first measurements reported in literature achieved with this new host. PMID:27137574

  8. Structural and electrical transport properties of La{sub 0.8}Sm{sub 0.05}K{sub 0.15}MnO{sub 3} manganites

    SciTech Connect

    Shaikh, M. W.; Mansuri, I.; Varshney, Dinesh

    2014-04-24

    Polycrystalline sample of single-phase La{sub 0.8}Sm{sub 0.05}K{sub 0.15}MnO{sub 3} perovskite compound have been synthesized by solid-state reaction route. X-ray diffraction patterns accompanied by Rietveld–refined crystal structure parameters reveal the rhombohedral structure with space group R 3C. Electrical resistivity infers transition from metallic to insulator phase at 537 K. The application of magnetic field of 8 T, suppresses the resistivity. The metallic resistivity is retraced by considering electron–phonon, electron–electron and electron-spin-fluctuation interactions while insulating behaviour is analysed with small polaron conduction model.

  9. Evidence for Retarded Pr ƒ; Hybridization and Tc Suppression in Y 1- xPr xSr 2Cu 2.85Re 0.15O 7

    NASA Astrophysics Data System (ADS)

    Das, A.; Castro, L. F.; Zelenay, I.; Suryanarayanan, R.

    1995-08-01

    We report on the preparation, X-ray diffraction, ac susceptibility, resistivity, and thermopower of Y 1- xPr xSr 2Cu 2.85Re 0.15O 7. We find that superconductivity is sustained up to a Pr concentration of 70%, which is greater than the 55% normally found in the Y 1- xPr xBa 2Cu 3O 7 system. It is proposed that the presence of Sr retards the Pr ƒ hybridization and the Tc suppression. It is pointed out that a better knowledge of structural and defect chemistry of Pr-containing cuprates is essential before applying any definite model to account for the data, as was also proposed earlier by R. Fehrenbacher and T. M. Rice ( Phys. Rev. Lett. 70, 3471, 1993).

  10. Positive magnetoconductance in YBa 2(Cu 0.9Fe 0.1) 3O y and YBa 2(Cu 0.85Fe 0.15) 3O y

    NASA Astrophysics Data System (ADS)

    Matsushita, A.; Aoki, H.; Matsumoto, T.

    1990-03-01

    The magnetoconductance was investigated for the superconductor YBa 2(Cu 0.9Fe 0.1) 3O y (Fe10) at various temperatures above Tc and for the non-superconductor YBa 2(Cu 0.85Fe 0.15) 3O y (Fe15) below 4.2 K. In Fe10 the magnetoconductance is negative above 211 K, while it is positive below 70 K where the temperature coefficient of the resistivity (TCR) is negative. The positive magnetoconductance observed in Fe10 shows a H2 dependence at lower magnetic fields. In Fe15 the magnetoconductance is negative at lower magnetic fields and turns to positive at higher magnetic fields of more than 2-3 T, and a H2 dependence is not observed. These types of behavior can be explained by a two-dimensional Anderson localization occuring at the CuO 2 plane.

  11. Magnetic susceptibility investigation of Bose-glass state in Ni0.85Cd0.15Cl2-4SC(NH2)2 at ultra-low temperatures

    NASA Astrophysics Data System (ADS)

    Yin, L.; Xia, J. S.; Sullivan, N. S.; Zapf, V. S.; Paduan-Filho, A.; Yu, R.; Roscilde, T.

    2012-12-01

    We report measurements of the AC susceptibility of a site-diluted quantum magnet Ni0.85Cd0.15Cl2-4SC(NH2)2 (15% Cd-doped dichloro-tetrakis-thiourea-Nickel, or Cd-DTN) down to 10 mK Below a crossover temperature Tcr ≍ 100 ~ 200mK, we find that the critical fields Hc for Bose-Einstein condensation obey the scaling relation |Hc(T)-Hc(0)| ~ Tα, with a novel and universal scaling exponent α ≍ 0.9, which is in agreement with numerical results from a theoretical model. Our findings provide strong evidence of the existence of a Bose glass phase in Cd-DTN, and they display a quantitative signature of the transition between a Bose glass and a Bose Einstein condensate.

  12. Structural and chemical analysis of pulsed laser deposited Mg xZn 1- xO hexagonal ( x = 0.15, 0.28) and cubic ( x = 0.85) thin films

    NASA Astrophysics Data System (ADS)

    Hullavarad, S. S.; Hullavarad, N. V.; Pugel, D. E.; Dhar, S.; Venkatesan, T.; Vispute, R. D.

    2008-02-01

    Hexagonal and cubic Mg xZn 1- xO thin films corresponding to optical band gaps of 3.52 eV, 4 eV and 6.42 eV for x = 0.15, 0.28 and 0.85 compositions were grown by pulsed laser deposition technique. The crystalline quality of the films was investigated by X-ray diffraction-rocking curve measurements and indicated a high degree of crystallinity with narrow FWHM's of 0.21°-0.59°. Rutherford back scattering-channeling spectroscopy provides channeling yields of 7-14% indicating the good crystalline quality of the thin films. X-Ray photoelectron spectroscopy measurements clearly indicated different level of oxidation states of Mg and Zn.

  13. Magnetism of Fe, Ni, and Zn in Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4}: Comparison of experiment and theory

    SciTech Connect

    Jayaram, B.; Chen, H.; Callaway, J.

    1995-08-01

    We have studied the magnetic and superconducting properties of Fe- , Ni- , and Zn-substituted Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4} bulk materials. The normal-state magnetic susceptibility of all samples is found to follow the Curie-Weiss law between 50 and 300 K. The magnitude of local moments deduced for Fe and Ni are 2.2{mu}{sub {ital B}} and 2{mu}{sub {ital B}}, respectively. The observed moment on Ni is attributed to Ni in a 3+ valency state. A magnetic moment of 0.8{mu}{sub {ital B}} is obtained in Zn-substituted samples. This is ascribed to the localized Cu{sup 2+} spins. The {ital T}{sub {ital c}} vs 3{ital d} ion concentration ({ital x}) curves indicate that Ni inhibits the {ital T}{sub {ital c}} of this system at an anomalously higher rate. In an effort to understand the correlation between the magnitude of the magnetic moment on the 3{ital d} ion and its role in the suppression of superconductivity, we have performed density-functional cluster calculations under local-spin-density approximations. The calculations support the following inferences drawn from the experiments: (i) Ni is in a 3+ state, (ii) the moment of 0.8{mu}{sub {ital B}} observed in Zn-substituted samples is due to localized Cu{sup 2+} spins, and (iii) Zn induces a moment of almost the same magnitude in both the electron-doped and the hole-doped La{sub 1.85}Sr{sub 0.15}CuO{sub 4} systems. We have also attempted to explain qualitatively the observed {ital T}{sub {ital c}} vs {ital x} behavior in the above systems using the effective single-band {ital t}-{ital J} model.

  14. Growth and Physiological Responses to Water Depths in Carex schmidtii Meinsh

    PubMed Central

    Yan, Hong; Liu, Ruiquan; Liu, Zinan; Wang, Xue; Luo, Wenbo; Sheng, Lianxi

    2015-01-01

    A greenhouse experiment was performed to investigate growth and physiological responses to water depth in completely submerged condition of a wetland plant Carex schmidtii Meinsh., one of the dominant species in the Longwan Crater Lake wetlands (China). Growth and physiological responses of C. schmidtii were investigated by growing under control (non-submerged) and three submerged conditions (5 cm, 15 cm and 25 cm water level). Total biomass was highest in control, intermediate in 5 cm treatment and lowest in the other two submerged treatments. Water depth prominently affected the first-order lateral root to main root mass ratio. Alcohol dehydrogenase (ADH) activity decreased but malondialdehyde (MDA) content increased as water depth increased. The starch contents showed no differences among the various treatments at the end of the experiment. However, soluble sugar contents were highest in control, intermediate in 5 cm and 15 cm treatments and lowest in 25 cm treatment. Our data suggest that submergence depth affected some aspects of growth and physiology of C. schmidtii, which can reduce anoxia damage not only through maintaining the non-elongation strategy in shoot part but also by adjusting biomass allocation to different root orders rather than adjusting root-shoot biomass allocation. PMID:26009895

  15. Characterization of Luminescent Minerals in CM2 Chondrite (Jbilet Winselwan)

    NASA Astrophysics Data System (ADS)

    Kiku, Y. K.; Ohgo, S. O.; Nishido, H. N.

    2014-09-01

    We have characterized luminescent minerals of forsterite, diopside and spinel in the CM2 chondrite (Jbilet Winselwan) using SEM-CL and to discuss the formation of the luminescent minerals under aqueous conditions.

  16. Benchmarking and performance analysis of the CM-2. [SIMD computer

    NASA Technical Reports Server (NTRS)

    Myers, David W.; Adams, George B., II

    1988-01-01

    A suite of benchmarking routines testing communication, basic arithmetic operations, and selected kernel algorithms written in LISP and PARIS was developed for the CM-2. Experiment runs are automated via a software framework that sequences individual tests, allowing for unattended overnight operation. Multiple measurements are made and treated statistically to generate well-characterized results from the noisy values given by cm:time. The results obtained provide a comparison with similar, but less extensive, testing done on a CM-1. Tests were chosen to aid the algorithmist in constructing fast, efficient, and correct code on the CM-2, as well as gain insight into what performance criteria are needed when evaluating parallel processing machines.

  17. Continuous thorium biosorption--dynamic study for critical bed depth determination in a fixed-bed reactor.

    PubMed

    Picardo, Marta Cristina; Ferreira, Ana Cristina de Melo; da Costa, Antonio Carlos Augusto

    2009-01-01

    The objective of the work was to evaluate the biosorption of thorium by the seaweed Sargassum filipendula in a dynamic system. Different bed depths were tested with the purpose of evaluating the critical bed depth for total uptake of the radioactive element. Several bed depths were tested, ranging from 5.0 to 40.0 cm. Bed depths tested presented distinct capacities to accumulate thorium. An increase in biosorption efficiency was observed with an increase in bed depth. The 30.0 cm bed produced an effluent still containing detectable levels of thorium. The critical bed depth suitable for a complete removal of thorium by S.filipendula biomass was equal to 40.0 cm. PMID:18614355

  18. CmWRKY15 Facilitates Alternaria tenuissima Infection of Chrysanthemum.

    PubMed

    Fan, Qingqing; Song, Aiping; Xin, Jingjing; Chen, Sumei; Jiang, Jiafu; Wang, Yinjie; Li, Xiran; Chen, Fadi

    2015-01-01

    Abscisic acid (ABA) has an important role in the responses of plants to pathogens due to its ability to induce stomatal closure and interact with salicylic acid (SA) and jasmonic acid (JA). WRKY transcription factors serve as antagonistic or synergistic regulators in the response of plants to a variety of pathogens. Here, we demonstrated that CmWRKY15, a group IIa WRKY family member, was not transcriptionally activated in yeast cells. Subcellular localization experiments in which onion epidermal cells were transiently transfected with CmWRKY15 indicated that CmWRKY15 localized to the nucleus in vivo. The expression of CmWRKY15 could be markedly induced by the presence of Alternaria tenuissima inoculum in chrysanthemum. Furthermore, the disease severity index (DSI) data of CmWRKY15-overexpressing plants indicated that CmWRKY15 overexpression enhanced the susceptibility of chrysanthemum to A. tenuissima infection compared to controls. To illustrate the mechanisms by which CmWRKY15 regulates the response to A. tenuissima inoculation, the expression levels of ABA-responsive and ABA signaling genes, such as ABF4, ABI4, ABI5, MYB2, RAB18, DREB1A, DREB2A, PYL2, PP2C, RCAR1, SnRK2.2, SnRK2.3, NCED3A, NCED3B, GTG1, AKT1, AKT2, KAT1, KAT2, and KC1were compared between transgenic plants and controls. In summary, our data suggest that CmWRKY15 might facilitate A. tenuissima infection by antagonistically regulating the expression of ABA-responsive genes and genes involved in ABA signaling, either directly or indirectly. PMID:26600125

  19. CmWRKY15 Facilitates Alternaria tenuissima Infection of Chrysanthemum

    PubMed Central

    Fan, Qingqing; Song, Aiping; Xin, Jingjing; Chen, Sumei; Jiang, Jiafu; Wang, Yinjie; Li, Xiran; Chen, Fadi

    2015-01-01

    Abscisic acid (ABA) has an important role in the responses of plants to pathogens due to its ability to induce stomatal closure and interact with salicylic acid (SA) and jasmonic acid (JA). WRKY transcription factors serve as antagonistic or synergistic regulators in the response of plants to a variety of pathogens. Here, we demonstrated that CmWRKY15, a group IIa WRKY family member, was not transcriptionally activated in yeast cells. Subcellular localization experiments in which onion epidermal cells were transiently transfected with CmWRKY15 indicated that CmWRKY15 localized to the nucleus in vivo. The expression of CmWRKY15 could be markedly induced by the presence of Alternaria tenuissima inoculum in chrysanthemum. Furthermore, the disease severity index (DSI) data of CmWRKY15-overexpressing plants indicated that CmWRKY15 overexpression enhanced the susceptibility of chrysanthemum to A. tenuissima infection compared to controls. To illustrate the mechanisms by which CmWRKY15 regulates the response to A. tenuissima inoculation, the expression levels of ABA-responsive and ABA signaling genes, such as ABF4, ABI4, ABI5, MYB2, RAB18, DREB1A, DREB2A, PYL2, PP2C, RCAR1, SnRK2.2, SnRK2.3, NCED3A, NCED3B, GTG1, AKT1, AKT2, KAT1, KAT2, and KC1were compared between transgenic plants and controls. In summary, our data suggest that CmWRKY15 might facilitate A. tenuissima infection by antagonistically regulating the expression of ABA-responsive genes and genes involved in ABA signaling, either directly or indirectly. PMID:26600125

  20. Focus cues affect perceived depth

    PubMed Central

    Watt, Simon J.; Akeley, Kurt; Ernst, Marc O.; Banks, Martin S.

    2007-01-01

    Depth information from focus cues—accommodation and the gradient of retinal blur—is typically incorrect in three-dimensional (3-D) displays because the light comes from a planar display surface. If the visual system incorporates information from focus cues into its calculation of 3-D scene parameters, this could cause distortions in perceived depth even when the 2-D retinal images are geometrically correct. In Experiment 1 we measured the direct contribution of focus cues to perceived slant by varying independently the physical slant of the display surface and the slant of a simulated surface specified by binocular disparity (binocular viewing) or perspective/texture (monocular viewing). In the binocular condition, slant estimates were unaffected by display slant. In the monocular condition, display slant had a systematic effect on slant estimates. Estimates were consistent with a weighted average of slant from focus cues and slant from disparity/texture, where the cue weights are determined by the reliability of each cue. In Experiment 2, we examined whether focus cues also have an indirect effect on perceived slant via the distance estimate used in disparity scaling. We varied independently the simulated distance and the focal distance to a disparity-defined 3-D stimulus. Perceived slant was systematically affected by changes in focal distance. Accordingly, depth constancy (with respect to simulated distance) was significantly reduced when focal distance was held constant compared to when it varied appropriately with the simulated distance to the stimulus. The results of both experiments show that focus cues can contribute to estimates of 3-D scene parameters. Inappropriate focus cues in typical 3-D displays may therefore contribute to distortions in perceived space. PMID:16441189

  1. Assimilation of Aerosol Optical Depths

    NASA Astrophysics Data System (ADS)

    Verver, Gé; Henzing, Bas

    Climate predictions are hampered by the large uncertainties involved in the estima- tion of the effects of atmospheric aerosol (IPCC,2001). These uncertainties are caused partly because sources and sinks as well as atmospheric processing of the different types of aerosol are not accurately known. Moreover, the climate impact (especially the indirect effect) of a certain distribution of aerosol is hard to quantify. There have been different approaches to reduce these uncertainties. In recent years intensive ob- servational campaigns such as ACE and INDOEX have been carried out, aiming to in- crease our knowledge of atmospheric processes that determine the fate of atmospheric aerosols and to quantify the radiation effects. With the new satellite instruments such as SCIAMACHY and OMI it will be possible in the near future to derive the ge- ographical distribution of the aerosol optical depths (AOD) and perhaps additional information on the occurrence of different aerosol types. The goal of the ARIA project (started in 2001) is to assimilate global satellite de- rived aerosol optical depth (AOD) in an off-line chemistry/transport model TM3. The TM3 model (Jeuken et al. 2001) describes sources, sinks, transformation and transport processes of different types of aerosol (mineral dust, carbon, sulfate, nitrate) that are relevant to radiative forcing. All meteorological input is provided by ECMWF. The assimilation procedure constrains the aerosol distribution produced by the model on the basis of aerosol optical depths observed by satellite. The product, i.e. an optimal estimation of global aerosol distribution, is then available for the calculation of radia- tive forcing. Error analyses may provide valuable information on deficiencies of the model. In the ARIA project it is tried to extract additional information on the type of aerosol present in the atmosphere by assimilating AOD at multiple wavelengths. First results of the ARIA project will be presented. The values

  2. Snow Depth Mapping at a Basin-Wide Scale in the Western Arctic Using UAS Technology

    NASA Astrophysics Data System (ADS)

    de Jong, T.; Marsh, P.; Mann, P.; Walker, B.

    2015-12-01

    Assessing snow depths across the Arctic has proven to be extremely difficult due to the variability of snow depths at scales from metres to 100's of metres. New Unmanned Aerial Systems (UAS) technology provides the possibility to obtain centimeter level resolution imagery (~3cm), and to create Digital Surface Models (DSM) based on the Structure from Motion method. However, there is an ongoing need to quantify the accuracy of this method over different terrain and vegetation types across the Arctic. In this study, we used a small UAS equipped with a high resolution RGB camera to create DSMs over a 1 km2 watershed in the western Canadian Arctic during snow (end of winter) and snow-free periods. To improve the image georeferencing, 15 Ground Control Points were marked across the watershed and incorporated into the DSM processing. The summer DSM was subtracted from the snowcovered DSM to deliver snow depth measurements across the entire watershed. These snow depth measurements were validated by over 2000 snow depth measurements. This technique has the potential to improve larger scale snow depth mapping across watersheds by providing snow depth measurements at a ~3 cm . The ability of mapping both shallow snow (less than 75cm) covering much of the basin and snow patches (up to 5 m in depth) that cover less than 10% of the basin, but contain a significant portion of total basin snowcover, is important for both water resource applications, as well as for testing snow models.

  3. Static stereo vision depth distortions in teleoperation

    NASA Technical Reports Server (NTRS)

    Diner, D. B.; Von Sydow, M.

    1988-01-01

    A major problem in high-precision teleoperation is the high-resolution presentation of depth information. Stereo television has so far proved to be only a partial solution, due to an inherent trade-off among depth resolution, depth distortion and the alignment of the stereo image pair. Converged cameras can guarantee image alignment but suffer significant depth distortion when configured for high depth resolution. Moving the stereo camera rig to scan the work space further distorts depth. The 'dynamic' (camera-motion induced) depth distortion problem was solved by Diner and Von Sydow (1987), who have quantified the 'static' (camera-configuration induced) depth distortion. In this paper, a stereo image presentation technique which yields aligned images, high depth resolution and low depth distortion is demonstrated, thus solving the trade-off problem.

  4. Shallow depth subsurface imaging with microwave holography

    NASA Astrophysics Data System (ADS)

    Zhuravlev, Andrei; Ivashov, Sergey; Razevig, Vladimir; Vasiliev, Igor; Bechtel, Timothy

    2014-05-01

    In this paper, microwave holography is considered as a tool to obtain high resolution images of shallowly buried objects. Signal acquisition is performed at multiple frequencies on a grid using a two-dimensional mechanical scanner moving a single transceiver over an area of interest in close proximity to the surface. The described FFT-based reconstruction technique is used to obtain a stack of plan view images each using only one selected frequency from the operating waveband of the radar. The extent of a synthetically-formed aperture and the signal wavelength define the plan view resolution, which at sounding frequencies near 7 GHz amounts to 2 cm. The system has a short depth of focus which allows easy selection of proper focusing plane. The small distance from the buried objects to the antenna does not prevent recording of clean images due to multiple reflections (as happens with impulse radars). The description of the system hardware and signal processing technique is illustrated using experiments conducted in dry sand. The microwave images of inert anti-personnel mines are demonstrated as examples. The images allow target discrimination based on the same visually-discernible small features that a human observer would employ. The demonstrated technology shows promise for modification to meet the specific practical needs required for humanitarian demining or in multi-sensor survey systems.

  5. Combined velocity and depth mapping on developing laboratory alluvial fans

    NASA Astrophysics Data System (ADS)

    Hamilton, P.; Strom, K. B.; Hoyal, D. C.

    2011-12-01

    Large-scale particle image velocimetry (LSPIV) is a nonintrusive method for measuring free-surface velocities using tracer patterns in a sequence of images. This method has been applied in both natural rivers and large-scale hydraulic models (Muste et al., 2008). Here the method is used to map channel and sheet flow velocity during the development of laboratory-scale alluvial fans. Measuring the time and space varying hydraulics on laboratory fans by traditional methods is not practical since flows are quite shallow (~1 cm). Additionally, the highly dynamic environment makes positioning of traditional probe-type instruments difficult and their physical presence could alter autogenic fan evolution. These difficulties can be overcome by using particle image velocimetry techniques. Furthermore, images collected in the LSPIV method can be used to extract flow depth using a calibrated dye-intensity method (Gran and Paola, 2001). This allows for simultaneous measurement of flow velocity and depth everywhere over the fan at any point in time. To validate the method, a set of controlled small-scale experiments were run for depths ranging from 0.2-1.5 cm and velocities from 10-100 cm/sec. Comparison of the LSPIV and dye-intensity method measurements to the known values indicated that the methodology was able to accurately capture simultaneous flow velocity and depth in this range of conditions, i.e., those encountered during the development of laboratory-scale alluvial fans and streams. The method is then used to map the hydraulics associated with various fan processes during development as demonstrated in figure 1. The ability to measure hydraulic properties during fan development is important since physical models provide an arena for observing the time evolution and morphodynamic feedback in depositional systems such as alluvial fans.

  6. Chondrules in the Murray CM2 meteorite and compositional differences between CM-CO and ordinary chondrite chondrules

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.; Wasson, J. T.

    1986-02-01

    Thirteen of the least aqueously altered chondrules in Murray (CM2) were analyzed for bulk compositions, by means of a broad beam electron microprobe, to explore the compositional differences between the CM-CO, and the ordinary chondrite OC chondrules. The CO chondrules are richer in refractory lithophiles and poorer in Cr, Mn, and volatile lithophiles than the OC chondrules; much lower refractory lithophile abundances in CM chondrules resulted from aqueous alteration. Evidence is found for two important lithophile precursor components of CM-CO chondrite chondrules: (1) pyroxene- and refractory-rich, FeO-poor, and (2) olivine-rich, refractoryand FeO-poor. It is suggested that the pyroxene- and refractory-rich, FeO-poor lithophile precursor component has formed by an incomplete evaporation of presolar silicates that brought these materials into the enstatite stability field.

  7. Cosmological signatures of tilted isocurvature perturbations: reionization and 21cm fluctuations

    SciTech Connect

    Sekiguchi, Toyokazu; Sugiyama, Naoshi; Tashiro, Hiroyuki; Silk, Joseph E-mail: hiroyuki.tashiro@asu.edu E-mail: naoshi@nagoya-u.jp

    2014-03-01

    We investigate cosmological signatures of uncorrelated isocurvature perturbations whose power spectrum is blue-tilted with spectral index 2∼depth as a powerful probe of a highly blue-tilted isocurvature primordial power spectrum. We also study the consequences for 21cm line fluctuations due to neutral hydrogens in minihalos. Combination of measurements of the reionization optical depth and 21cm line fluctuations will provide complementary probes of a highly blue-tilted isocurvature power spectrum.

  8. New Development of the Online Integrated Climate-Chemistry model framwork (RegCM-CHEM4)

    NASA Astrophysics Data System (ADS)

    Zakey, A. S.; Shalaby, A. K.; Solmon, F.; Giorgi, F.; Tawfik, A. B.; Steiner, A. L.; Baklanov, A.

    2012-04-01

    The RegCM-CHEM4 is a new online integrated climate-chemistry model based on the regional climate model (RegCM4). The RegCM4 developed at the Abdus Salam International Centre for Theoretical Physics (ICTP), is a hydrostatic, sigma coordinate model. Tropospheric gas-phase chemistry is integrated into the climate model using the condensed version of the Carbon Bond Mechanism CBM-Z with lumped species that represent broad categories of organics based on carbon bond structure. The computationally rapid radical balance method RBM is coupled as a chemical solver to the gas-phase mechanism. Photolysis rates are determined as a function of meteorological and chemical inputs and interpolated from an array of pre-determined values based on the Tropospheric Ultraviolet-Visible Model (TUV) with cloud cover corrections. Cloud optical depths and cloud altitudes from RegCM-CHEM4 are used in the photolysis calculations, thereby directly coupling the photolysis rates and chemical reactions to meteorological conditions at each model time step. In this study, we evaluate the model over Europe for two different time scales: (1) an event-based analysis of the ozone episode associated with the heat wave of August 2003 and (2) a climatological analysis of a six-year simulation (2000-2005). For the episode analysis, model simulations show a good agreement with the European Monitoring and Evaluation Program (EMEP) observations of hourly ozone over different regions in Europe and capture ozone concentrations during and after the summer 2003 heat wave event. Analysis of the full six years of simulation indicates that the coupled chemistry-climate model can reproduce the seasonal cycle of ozone, with an overestimation of ozone in the non-event years of 5-15 ppb depending on the geographic region. Overall, the ozone and ozone precursor evaluation shows the feasibility of using RegCM-CHEM4 for decadal-length simulations of chemistry-climate interactions.

  9. THE SIGNATURES OF PARTICLE DECAY IN 21 cm ABSORPTION FROM THE FIRST MINIHALOS

    SciTech Connect

    Vasiliev, Evgenii O.; Shchekinov, Yuri A. E-mail: yus@sfedu.ru

    2013-11-01

    The imprint of decaying dark matter (DM) particles on the characteristics of the {sup 2}1 cm forest{sup —}absorption at 21 cm from minihalos in the spectra of distant radio-loud sources—is considered within a one-dimensional, self-consistent hydrodynamic description of minihalos from their turnaround point to virialization. The most pronounced influence of decaying DM on the evolution of minihalos is found in the mass range M = 10{sup 5}-10{sup 6} M{sub ☉}, for which unstable DM with a current upper limit on its ionization rate of ξ{sub L} = 0.59 × 10{sup –25} s{sup –1} reduces the 21 cm optical depth by an order of magnitude compared with the standard recombination scenario. Even a rather modest ionization, ξ ∼ 0.3ξ{sub L}, practically erases absorption features and results in a considerable decrease (by factor of more than 2.5) of the number of strong (W{sub ν}{sup obs}∼>0.3 kHz at z ≅ 10) absorptions. In such circumstances, broadband observations are more suitable for inferring the physical conditions of the absorbing gas. X-ray photons from stellar activity of the initial episodes of star formation can compete with the contribution from decaying DM only at z < 10. Therefore, observing the 21 cm signal will allow us to follow the evolution of decaying DM particles in the redshift range z = 10-15. On the other hand, a non-detection of the 21 cm signal in the frequency range ν < 140 MHz can establish a lower limit on the ionization rate from decaying DM.

  10. Simulating the 21 cm signal from reionization including non-linear ionizations and inhomogeneous recombinations

    NASA Astrophysics Data System (ADS)

    Hassan, Sultan; Davé, Romeel; Finlator, Kristian; Santos, Mario G.

    2016-04-01

    We explore the impact of incorporating physically motivated ionization and recombination rates on the history and topology of cosmic reionization and the resulting 21 cm power spectrum, by incorporating inputs from small-volume hydrodynamic simulations into our semi-numerical code, SIMFAST21, that evolves reionization on large scales. We employ radiative hydrodynamic simulations to parametrize the ionization rate Rion and recombination rate Rrec as functions of halo mass, overdensity and redshift. We find that Rion scales superlinearly with halo mass ({R_ion}∝ M_h^{1.41}), in contrast to previous assumptions. Implementing these scalings into SIMFAST21, we tune our one free parameter, the escape fraction fesc, to simultaneously reproduce recent observations of the Thomson optical depth, ionizing emissivity and volume-averaged neutral fraction by the end of reionization. This yields f_esc=4^{+7}_{-2} per cent averaged over our 0.375 h-1 Mpc cells, independent of halo mass or redshift, increasing to 6 per cent if we also constrain to match the observed z = 7 star formation rate function. Introducing superlinear Rion increases the duration of reionization and boosts small-scale 21 cm power by two to three times at intermediate phases of reionization, while inhomogeneous recombinations reduce ionized bubble sizes and suppress large-scale 21 cm power by two to three times. Gas clumping on sub-cell scales has a minimal effect on the 21 cm power. Superlinear Rion also significantly increases the median halo mass scale for ionizing photon output to ˜ 1010 M⊙, making the majority of reionizing sources more accessible to next-generation facilities. These results highlight the importance of accurately treating ionizing sources and recombinations for modelling reionization and its 21 cm power spectrum.

  11. DEEP 21 cm H I OBSERVATIONS AT z {approx} 0.1: THE PRECURSOR TO THE ARECIBO ULTRA DEEP SURVEY

    SciTech Connect

    Freudling, Wolfram; Zwaan, Martin; Staveley-Smith, Lister; Meyer, Martin; Catinella, Barbara; Minchin, Robert; Calabretta, Mark; Momjian, Emmanuel; O'Neil, Karen

    2011-01-20

    The 'ALFA Ultra Deep Survey' (AUDS) is an ongoing 21 cm spectral survey with the Arecibo 305 m telescope. AUDS will be the most sensitive blind survey undertaken with Arecibo's 300 MHz Mock spectrometer. The survey searches for 21 cm H I line emission at redshifts between 0 and 0.16. The main goals of the survey are to investigate the H I content and probe the evolution of H I gas within that redshift region. In this paper, we report on a set of precursor observations with a total integration time of 53 hr. The survey detected a total of eighteen 21 cm emission lines at redshifts between 0.07 and 0.15 in a region centered around {alpha}{sub 2000} {approx} 0{sup h}, {delta} {approx} 15{sup 0}42'. The rate of detection is consistent with the one expected from the local H I mass function. The derived relative H I density at the median redshift of the survey is {rho}{sub H{sub I}}[z = 0.125] = (1.0 {+-} 0.3){rho}{sub 0}, where {rho}{sub 0} is the H I density at zero redshift.

  12. Determining the relative extent of alteration in CM chondrites

    NASA Technical Reports Server (NTRS)

    Browning, Lauren B.; Mcsween, Harry Y., Jr.; Zolensky, Michael

    1993-01-01

    The aqueous alteration of CM chondrites provides a record of the processes attending the earliest stages of parent body evolution. However, resolving the alteration pathways of chondritic evolution requires a means for distinguishing the relative extent of alteration that individual samples have experienced. Three new indices for gauging the relative degree of alteration in CM chondrites based on modal and compositional analyses of 7 CM falls were proposed. The proposed alteration parameters are consistent with the basic tenets of several previous models and correlate with additional indices to produce an integrated method for determining the relative extent of alteration. The model predicts the following order of progressive alteration: Murchison (MC) is less than or equal to Bells (BL) is less than Murray (MY) is less than Cochabamba (CC) is less than Mighei (MI) is less than Nogoya (NG) is less than or equal to Cold Bokkeveld (CB). The broad range of CM phyllosilicate compositions observed within individual meteorites is fundamental to the characterization of the aqueous alteration process. Chemical analyses of CM phyllosilicates suggest that these phases became systematically enriched in Mg and depleted in Fe with increasing alteration.

  13. Determining the relative extent of alteration in CM chondrites

    NASA Astrophysics Data System (ADS)

    Browning, Lauren B.; McSween, Harry Y., Jr.; Zolensky, Michael

    1993-03-01

    The aqueous alteration of CM chondrites provides a record of the processes attending the earliest stages of parent body evolution. However, resolving the alteration pathways of chondritic evolution requires a means for distinguishing the relative extent of alteration that individual samples have experienced. Three new indices for gauging the relative degree of alteration in CM chondrites based on modal and compositional analyses of 7 CM falls were proposed. The proposed alteration parameters are consistent with the basic tenets of several previous models and correlate with additional indices to produce an integrated method for determining the relative extent of alteration. The model predicts the following order of progressive alteration: Murchison (MC) is less than or equal to Bells (BL) is less than Murray (MY) is less than Cochabamba (CC) is less than Mighei (MI) is less than Nogoya (NG) is less than or equal to Cold Bokkeveld (CB). The broad range of CM phyllosilicate compositions observed within individual meteorites is fundamental to the characterization of the aqueous alteration process. Chemical analyses of CM phyllosilicates suggest that these phases became systematically enriched in Mg and depleted in Fe with increasing alteration.

  14. Advancing precision cosmology with 21 cm intensity mapping

    NASA Astrophysics Data System (ADS)

    Masui, Kiyoshi Wesley

    In this thesis we make progress toward establishing the observational method of 21 cm intensity mapping as a sensitive and efficient method for mapping the large-scale structure of the Universe. In Part I we undertake theoretical studies to better understand the potential of intensity mapping. This includes forecasting the ability of intensity mapping experiments to constrain alternative explanations to dark energy for the Universe's accelerated expansion. We also considered how 21 cm observations of the neutral gas in the early Universe (after recombination but before reionization) could be used to detect primordial gravity waves, thus providing a window into cosmological inflation. Finally we showed that scientifically interesting measurements could in principle be performed using intensity mapping in the near term, using existing telescopes in pilot surveys or prototypes for larger dedicated surveys. Part II describes observational efforts to perform some of the first measurements using 21 cm intensity mapping. We develop a general data analysis pipeline for analyzing intensity mapping data from single dish radio telescopes. We then apply the pipeline to observations using the Green Bank Telescope. By cross-correlating the intensity mapping survey with a traditional galaxy redshift survey we put a lower bound on the amplitude of the 21 cm signal. The auto-correlation provides an upper bound on the signal amplitude and we thus constrain the signal from both above and below. This pilot survey represents a pioneering effort in establishing 21 cm intensity mapping as a probe of the Universe.

  15. CM Carbonaceous Chondrite Lithologies and Their Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Gregory, Timothy; Takenouchi, Atsushi; Nishiizumi, Kunihiko; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Velbel, Michael; Imae, Naoya; Yamaguchi, Akira

    2015-01-01

    The CMs are the most commonly falling C chondrites, and therefore may be a major component of C-class asteroids, the targets of several current and future space missions. Previous work [1] has concluded that CM chondrites fall into at least four distinct cosmic ray space exposure (CRE) age groups (0.1 million years, 0.2 million years, 0.6 million years and greater than 2.0 million years), an unusually large number, but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios, or something else entirely. The objective of this study is to investigate the diversity of lithologies which make up CM chondrites, in order to determine whether the different exposure ages correspond to specific, different CM lithologies, which permit us to constrain the history of the CM parent body(ies). We have already reported significant petrographic differences among CM chondrites [2-4]. We report here our new results.

  16. Enhancement of critical current density in a Ca0.85La0.15Fe(As0.92Sb0.08)2 superconductor with T c = 47 K through 3 MeV proton irradiation

    NASA Astrophysics Data System (ADS)

    Park, Akiyoshi; Mine, Akinori; Yamada, Tatsuhiro; Ohtake, Fumiaki; Akiyama, Hiroki; Sun, Yue; Pyon, Sunseng; Tamegai, Tsuyoshi; Kitahama, Yutaka; Mizukami, Tasuku; Kudo, Kazutaka; Nohara, Minoru; Kitamura, Hisashi

    2016-05-01

    We examine the critical current density (J c) of Ca{}1-xLa x Fe(As{}1-ySb y )2, a 112-type iron-based superconductor (IBS) with {T}{{c}} = 47 K, via magneto-optical imaging and magnetization measurements. We assert that the large self-field J c of 2.2× {10}6 A cm- 2 at 2 K is a strong indication that it is a bulk superconductor with spatially homogeneous superconductivity. A 2.8-fold enhancement in J c to 6.2× {10}6 A cm- 2 was achieved through artificially engineering pinning centers by irradiating 3 MeV protons with a total dosage of 1.0× {10}16 {{cm}}-2. The results not only demonstrate the potential of 112-type IBSs for application but also enrich the current understanding of the role of artificial defects in IBSs.

  17. Effect of phosphorus additions on the sintering and transport properties of proton conducting BaZr{sub 0.85}Y{sub 0.15}O{sub 3-{delta}}

    SciTech Connect

    Soares, H.S.; Zhang, X.; Antunes, I.; Frade, J.R.; Mather, G.C.; Fagg, D.P.

    2012-07-15

    The influence of phosphorous additions on the sintering and electrical transport properties of the proton-conducting perovskite BaZr{sub 0.85}Y{sub 0.15}O{sub 3-{delta}} (BZY) has been studied with a view to the use of phosphates as typical dispersants for the formation of stabilised solid suspensions or as possible sintering aids. P{sub 2}O{sub 5} additions, (1-x)BZY{center_dot}xP{sub 2}O{sub 5}, monotonously promote densification in the intermediate compositional range 0.04{<=}x{<=}0.08. Nonetheless, BZY reacts with phosphorous forming the phase Ba{sub 3}(PO{sub 4}){sub 2} at temperatures as low as 600 Degree-Sign C. The associated loss of Ba from the perovskite, leads to a decrease in the perovskite lattice parameter, the formation of yttria-based impurity phases and impaired grain growth. Such reaction has an extremely detrimental effect on bulk and grain boundary conductivities. It is, therefore, vital that the current results are taken into account by the protonics community when attempting to prepare the stabilised solid suspensions of BZY nanopowders required for thin ceramic applications. Alternative dispersants to phosphate esters must be found. - Graphical Abstract: Sintering experiments performed at 1500 Degree-Sign C for 5 h and at 1400 Degree-Sign C for 24 h of (1-x)BaZr{sub 0.85}Y{sub 0.15}O{sub 3-{delta}}{center_dot}xP{sub 2}O{sub 5} in the range x=0-0.10. Highlights: Black-Right-Pointing-Pointer P{sub 2}O{sub 5} additions, (1-x)BZY{center_dot}xP{sub 2}O{sub 5}, promote densification in the intermediate compositional range 0.04{<=}x{<=}0.08. Black-Right-Pointing-Pointer BZY reacts with phosphorous forming the phase Ba{sub 3}(PO{sub 4}){sub 2} at temperatures as low as 600 Degree-Sign C. Black-Right-Pointing-Pointer Detrimental effects on bulk and grain boundary conductivities are shown. Black-Right-Pointing-Pointer Alternative dispersants to phosphate esters must be found.

  18. CM-2 Environmental / Modal Testing of Spacehab Racks

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Goodnight, Thomas W.; Farkas, Michael A.

    2001-01-01

    Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS 107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the Shuttle.

  19. CM-2 Environmental/Modal Testing of SPACEHAB Racks

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Goodnight, Thomas W.

    2001-01-01

    Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that will launch on shuttle mission STS-107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack-level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the shuttles.

  20. Differentiating CDM and baryon isocurvature models with 21 cm fluctuations

    SciTech Connect

    Kawasaki, Masahiro; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: sekiguti@icrr.u-tokyo.ac.jp

    2011-10-01

    We discuss how one can discriminate models with cold dark matter (CDM) and baryon isocurvature fluctuations. Although current observations such as cosmic microwave background (CMB) can severely constrain the fraction of such isocurvature modes in the total density fluctuations, CMB cannot differentiate CDM and baryon ones by the shapes of their power spectra. However, the evolution of CDM and baryon density fluctuations are different for each model, thus it would be possible to discriminate those isocurvature modes by extracting information on the fluctuations of CDM/baryon itself. We discuss that observations of 21 cm fluctuations can in principle differentiate these modes and demonstrate to what extent we can distinguish them with future 21 cm surveys. We show that, when the isocurvature mode has a large blue-tilted initial spectrum, 21 cm surveys can clearly probe the difference.

  1. Ion accelerator systems for high power 30-cm thruster operation

    NASA Technical Reports Server (NTRS)

    Aston, G.

    1982-01-01

    An investigation of two- and three-grid accelerator systems for high power ion thruster operation has been performed. Two-grid translation tests show that overcompensation of the 30-cm thruster SHAG (Small Hole Accelerator Grid) leads to a premature impingement limit. By better matching the SHAG grid set spacing to the 30-cm thruster radial plasma density variation and by incorporating grid compensation only sufficient to maintain grid hole axial alignment, it is shown that beam current gains as large as 50% can be realized. Three-grid translation tests performed with a simulated 30-cm thruster discharge chamber show that substantial beamlet steering can be reliably affected by decelerator grid translation only, at net-to-total voltage ratios as low as 0.05.

  2. A model for sunspot associated emission at 6 cm wavelength

    NASA Technical Reports Server (NTRS)

    Alissandrakis, C. E.; Kundu, M. R.; Lantos, P.

    1980-01-01

    Two-dimensional maps of total intensity and circular polarization of a sunspot region at 6 cm have been calculated using a simple model for the chromosphere-corona transition region and observations of the longitudinal component of the photospheric magnetic field. The calculations are in good agreement with the high resolution observations of the same sunspot region at 6 cm, obtained with the Westerbork Synthesis Radio Telescope. It is shown that the 6 cm radiation is predominantly due to gyroresonance absorption process at the second and third harmonics of the gyrofrequency (H = 900-600 G). Estimates of the conductive flux and the electron density in the transition region above the sunspot are also given.

  3. VLA observations of Uranus at 1. 3-20 cm

    SciTech Connect

    De Pater, I.; Gulkis, S.

    1988-08-01

    Observations of Uranus, obtained with resolution 0.5-1.2 arcsec at wavelengths 1.3, 2, 6, and 20 cm using the A and B configurations of the VLA in June-July 1982, October 1983, and February 1984, are reported. The disk-averaged brightness temperatures (DABTs) are determined by model fitting, and the results are presented in extensive graphs and contour maps and characterized in detail. Findings discussed include: (1) an overall spectrum which is relatively flat above 6 cm, (2) 1.3-6-cm brightness which is concentrated nearer to the pole than to the subsolar point, and (3) small changes in DABT from 1982 to 1983/1984 (consistent with an explanation based on a pole-equator temperature gradient). 16 references.

  4. Aeration equipment for small depths

    NASA Astrophysics Data System (ADS)

    Sluše, Jan; Pochylý, František

    2015-05-01

    Deficit of air in water causes complications with cyanobacteria mainly in the summer months. Cyanobacteria is a bacteria that produces poison called cyanotoxin. When the concentration of cyanobacteria increases, the phenomena "algal bloom" appears, which is very toxic and may kill all the organisms. This article describes new equipment for aeration of water in dams, ponds and reservoirs with small depth. This equipment is mobile and it is able to work without any human factor because its control is provided by a GPS module. The main part of this equipment consists of a floating pump which pumps water from the surface. Another important part of this equipment is an aerator where water and air are blended. Final aeration process runs in the nozzles which provide movement of all this equipment and aeration of the water. Simulations of the flow are solved by multiphase flow with diffusion in open source program called OpenFOAM. Results will be verified by an experiment.

  5. [Effect of fertilization depth on 15N-urea absorption, utilization and loss in dwarf apple trees].

    PubMed

    Ding, Ning; Chen, Qian; Xu, Hai-gang; Ji, Meng-meng; Jiang, Han; Jiang, Yuan-mao

    2015-03-01

    Five-year-old 'Fuji'3/M26/M. hupehensis Rehd. seedlings were treated by 15N tracer to study the effects of fertilization depth (0, 20 and 40 cm) on 15N-urea absorption, distribution, utilization and loss in soil. The results showed that the plant leaf area, chlorophyll content and total N of apple leaves in 20 cm treatment were obviously higher than 0 cm and 40 cm treatments. The 15N derived from fertilizer (Ndff) in different organs of apple plant under different depths were significantly different, and the Ndff was the highest in roots at the full-bloom stage, and then in perennial branches. During the shoot rapid-growing and flower bud differentiation stage, the Ndff of new organs higher than that of the storage organs, and the Ndff of different organs were high level at fruit rapid-expanding stage, and the Ndff of fruit was the highest. The distribution ratio of 15N at fruit maturity stage was significantly different under fertilization depths, and that of the vegetative and repro- ductive organs of 20 cm treatment were obviously higher than 0 cm and 40 cm treatments, but that of the storage organs of 20 cm treatment was lower than 0 cm and 40 cm treatments. At fruit maturity stage, 15N utilization rate of apple plant of 20 cm treatment was 24.0%, which was obviously higher than 0 cm (14.1%) and 40 cm (7.6%) treatments, and 15N loss rate was 54.0%, which was obviously lower than 0 cm (67.8%) and 40 cm (63.5%) treatments. With the increase of fertilization depths, the N residue in soil increased sharply. PMID:26211056

  6. Precise measurements of primordial power spectrum with 21 cm fluctuations

    SciTech Connect

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: oyamayo@post.kek.jp E-mail: tomot@cc.saga-u.ac.jp

    2013-10-01

    We discuss the issue of how precisely we can measure the primordial power spectrum by using future observations of 21 cm fluctuations and cosmic microwave background (CMB). For this purpose, we investigate projected constraints on the quantities characterizing primordial power spectrum: the spectral index n{sub s}, its running α{sub s} and even its higher order running β{sub s}. We show that future 21 cm observations in combinations with CMB would accurately measure above mentioned observables of primordial power spectrum. We also discuss its implications to some explicit inflationary models.

  7. Evidence for live 247Cm in the early solar system

    USGS Publications Warehouse

    Tatsumoto, M.; Shimamura, T.

    1980-01-01

    Variations of the 238U/235U ratio in the Allende meteorite, ranging from -35% to + 19%, are interpreted as evidence of live 247Cm in the early Solar System. The amounts of these and other r-products in the Solar System indicate values of (9,000??3,000) Myr for the age of the Galaxy and ??? 8 Myr for the time between the end of nucleosynthesis and the formation of meteoritic grains. Three possible explanations are presented for the different values of the latter time period which are indicated by the decay products of 247Cm, 26Al, 244Pu and 129I. ?? 1980 Nature Publishing Group.

  8. Cycle life testing of 8-cm mercury ion thruster cathodes

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.

    1976-01-01

    Two main cathodes have successfully completed 2800 and 1980 cycles and three neutralizers, 3928, 3050, and 2850 cycles in ongoing cycle life tests of flight-type cathode-isolator-vaporizer and neutralizer-isolator-vaporizer assemblies for the 4.45 mN 8-cm Hg ion thruster system. Each cycle included one hour of cathode operation. Starting and operating conditions simulated those expected in a typical auxiliary propulsion mission duty cycle. The cycle life test results are presented along with results of an insert comparison test which led to the selection of a rolled foil insert type for the 8-cm Engineering Model Thruster cathodes.

  9. SU-E-J-197: Investigation of Microsoft Kinect 2.0 Depth Resolution for Patient Motion Tracking

    SciTech Connect

    Silverstein, E; Snyder, M

    2015-06-15

    Purpose: Investigate the use of the Kinect 2.0 for patient motion tracking during radiotherapy by studying spatial and depth resolution capabilities. Methods: Using code written in C#, depth map data was abstracted from the Kinect to create an initial depth map template indicative of the initial position of an object to be compared to the depth map of the object over time. To test this process, simple setup was created in which two objects were imaged: a 40 cm × 40 cm board covered in non reflective material and a 15 cm × 26 cm textbook with a slightly reflective, glossy cover. Each object, imaged and measured separately, was placed on a movable platform with object to camera distance measured. The object was then moved a specified amount to ascertain whether the Kinect’s depth camera would visualize the difference in position of the object. Results: Initial investigations have shown the Kinect depth resolution is dependent on the object to camera distance. Measurements indicate that movements as small as 1 mm can be visualized for objects as close as 50 cm away. This depth resolution decreases linearly with object to camera distance. At 4 m, the depth resolution had decreased to observe a minimum movement of 1 cm. Conclusion: The improved resolution and advanced hardware of the Kinect 2.0 allows for increase of depth resolution over the Kinect 1.0. Although obvious that the depth resolution should decrease with increasing distance from an object given the decrease in number of pixels representing said object, the depth resolution at large distances indicates its usefulness in a clinical setting.

  10. Simultaneous First-Order Valence and Oxygen Vacancy Order/Disorder Transitions in (Pr0.85Y0.15)0.7Ca0.3CoO3-δ via Analytical Transmission Electron Microscopy.

    PubMed

    Gulec, Ahmet; Phelan, Daniel; Leighton, Chris; Klie, Robert F

    2016-01-26

    Perovskite cobaltites have been studied for years as some of the few solids to exhibit thermally driven spin-state crossovers. The unanticipated first-order spin and electronic transitions recently discovered in Pr-based cobaltites are notably different from these conventional crossovers, and are understood in terms of a unique valence transition. In essence, the Pr valence is thought to spontaneously shift from 3+ toward 4+ on cooling, driving subsequent transitions in Co valence and electronic/magnetic properties. Here, we apply temperature-dependent transmission electron microscopy and spectroscopy to study this phenomenon, for the first time with atomic spatial resolution, in the prototypical (Pr0.85Y0.15)0.70 Ca0.30CoO3-δ. In addition to the direct spectroscopic observation of charge transfer between Pr and Co at the 165 K transition (on both the Pr and O edges), we also find a simultaneous order/disorder transition associated with O vacancies. Remarkably, the first-order valence change drives a transition between ordered and random O vacancies, at constant O vacancy density, demonstrating reversible crystallization of such vacancies even at cryogenic temperatures. PMID:26592896

  11. Inhibition of the hemorrhagic and proteolytic activities of Lansberg's hognose pit viper (Porthidium lansbergii hutmanni) venom by opossum (Didelphis marsupialis) serum: isolation of Didelphis marsupialis 0.15Dm fraction on DEAE-cellulose chromatography.

    PubMed

    Pineda, María E; Girón, María E; Estrella, Amalid; Sánchez, Elda E; Aguilar, Irma; Fernandez, Irma; Vargas, Alba M; Scannone, Héctor; Rodríguez-Acosta, Alexis

    2008-01-01

    Earlier studies have revealed the ability of sera from several mammals to neutralize the toxic effects of snake venom. The Venezuelan opossum (Didelphis marsupialis) is one that has been found to inhibit hemorrhagic and proteolytic activities of venoms from many species of snakes. In this article it is shown that the opossum sera and its 0.15DM fraction were able to completely neutralize both hemorrhagic and hydrolysis (proteolysis) of casein effects induced by venom of the Lansberg's hognose pit viper (Porthidium lansbergii hutmanni). We have used DEAE-cellulose ion exchange chromatography to collect protein fractions from D. marsupialis sera which were able to defend mice from the lethal effects of P.l. hutmanni venom. The fractions separated were homogeneous by conventional electrophoresis using SDS-PAGE. The protein bands obtained contained molecular weights of approximately 6 to 220 kDa. These results revealed the presence of proteases inhibitors in the opossum sera fractions and the inhibition of venom activity by opossum sera suggesting a reciprocal adaptation at the molecular level. PMID:18800269

  12. Evidence of glassy ferromagnetic phase and kinetic arrest of electronic phase in Sm0.35Pr0.15Sr0.5MnO3 manganites

    NASA Astrophysics Data System (ADS)

    Giri, S. K.; Nath, T. K.

    2012-07-01

    The effect of doping of rare earth Pr3+ ion as a replacement of Sm3+ in Sm0.5Sr0.5MnO3 is investigated. Temperature dependent dc and ac magnetic susceptibility, resistivity, magnetoresistance measurements on chemically synthesized (Sm0.5-xPrx)Sr0.5MnO3 show various unusual features with doping level x=0.15. The frequency independent ferromagnetic to paramagnetic transition at higher temperature (∼191 K) followed by a frequency dependent reentrant magnetic transition at lower temperature (∼31 K) has been observed. The nature of this frequency dependent reentrant magnetic transition is described by a critical slowing down model of spin glasses. From non-linear ac susceptibility measurements it has been confirmed that the finite size ferromagnetic clusters are formed as a consequence of intrinsic phase separation, and undergo spin glass-like freezing below a certain temperature. There is an unusual observation of a 2nd harmonic peak in the non-linear ac susceptibility around this reentrant magnetic transition at low temperature (∼31 K). Arrott plots at 10 and 30 K confirm the existence of glassy ferromagnetism below this low temperature reentrant transition. Electronic- and magneto-transport measurements show a strong magnetic field-temperature history dependence and strong irreversibility with respect to the sweeping of magnetic field. These results are attributed to the effect of phase separation and kinetic arrest of the electronic phase in this phase separated manganite at low temperatures.

  13. Synthesis and characterization of electron doped La{sub 0.85}Te{sub 0.15}MnO{sub 3} thin film grown on LaAlO{sub 3} substrate by pulsed laser deposition technique

    SciTech Connect

    Bhat, Irshad Husain, Shahid; Patil, S. I.; Khan, Wasi; Ali, S. Asad

    2015-06-24

    We report the structural, morphological and magneto-transport properties of electron doped La{sub 0.85}Te{sub 0.15}MnO{sub 3} (LTMO) thin film grown on (001) LaAlO{sub 3} single crystal substrate by pulsed laser deposition (PLD). X-ray diffraction (XRD) results confirm that the film has good crystalline quality, single phase, and c-axis orientation. The atomic force microscopy (AFM) results have revealed that the film consists of grains with the average size in a range of 20–30 nm and root-mean square (rms) roughness of 0.27nm. The resistivity versus temperature measurement exhibits an insulator to metal transition (MIT). We have noticed a huge value of magnetoresistance (∼93%) close to MIT in presence of 8T field. X-ray photoemission spectroscopy confirms the electron doping and suggests that Te ions could be in the Te{sup 4+} state, while the Mn ions stay in the Mn{sup 2+} and Mn{sup 3+} valence state.

  14. Absence of nematic order in the pressure-induced intermediate phase of the iron-based superconductor B a0.85K0.15F e2A s2

    NASA Astrophysics Data System (ADS)

    Zheng, Yan; Tam, Pok Man; Hou, Jianqiang; Böhmer, Anna E.; Wolf, Thomas; Meingast, Christoph; Lortz, Rolf

    2016-03-01

    The hole doped Fe-based superconductors B a1-xAxF e2A s2 (where A =Na or K) show a particularly rich phase diagram. It was observed that an intermediate reentrant tetragonal phase, in which the C4 fourfold rotational symmetry is restored, forms within the orthorhombic antiferromagnetically ordered stripe-type spin density wave state above the superconducting transition [S. Avci et al., Nat. Commun. 5, 3845 (2014);, 10.1038/ncomms4845 A. E. Böhmer et al., Nat. Commun. 6, 7911 (2015), 10.1038/ncomms8911]. A similar intermediate phase was reported to appear if pressure is applied to underdoped B a1-xKxF e2A s2 [E. Hassinger et al., Phys. Rev. B 86, 140502(R) (2012), 10.1103/PhysRevB.86.140502]. Here we report data of the electric resistivity, Hall effect, specific heat, and the thermoelectric Nernst and Seebeck coefficients measured on a B a0.85K0.15F e2A s2 single crystal under pressure up to 5.5 GPa. The data reveal a coexistence of the intermediate phase with filamentary superconductivity. The Nernst coefficient shows a large signature of nematic order that coincides with the stripe-type spin density wave state up to optimal pressure. In the pressure-induced intermediate phase the nematic order is removed, thus confirming that its nature is a reentrant tetragonal phase.

  15. Structural, magnetic and magnetocaloric properties of polycrystalline La0.67Ba0.33- x Zn x MnO3 (x = 0.15 and 0.2) manganites

    NASA Astrophysics Data System (ADS)

    Zaidi, Asma.; Mohamed, Za.; Dhahri, J.; Hlil, E. K.; Alharbi, T.; Zaidi, M.

    2016-04-01

    We report on the structural, magnetic and magnetocaloric properties of manganite La0.67Ba0.33- x Zn x MnO3 (x = 0.15 and 0.2). X-ray diffraction studies show that all samples crystallize with the rhombohedral symmetry within the space Roverline{3} c. The magnetic and magnetocaloric properties of polycrystalline perovskite were investigated from the measured magnetization data of the samples as a function of the applied magnetic field. The associated magnetic entropy change close to their respective Curie temperature T C and the relative cooling power (RCP) have been determined. It was found that the maximum change in magnetic entropy of La0.67Ba0.33- x Zn x MnO3 samples reached 3.4 J/kg K at T C = 260 K for a magnetic field of 5 T and RCP = 223.77 J/kg. In view of these results, La0.67Ba0.33- x Zn x MnO3 compounds are potential candidates for magnetic refrigeration.

  16. Effect of substrate and orientation on charge ordering behaviors in epitaxial Pr{sub 0.5}Ca{sub 0.35}Sr{sub 0.15}MnO{sub 3} films

    SciTech Connect

    Yang, H. W.; Hu, F. X.; Sun, J. R. E-mail: jrsun@iphy.ac.cn; Wang, C.; Cai, R. S.; Wang, Y. Q. E-mail: jrsun@iphy.ac.cn

    2015-05-07

    The charge ordering (CO) behaviors of Pr{sub 0.5}Ca{sub 0.35}Sr{sub 0.15}MnO{sub 3} films grown on STO(100), STO(110) and LAO(100) are systematically investigated by transport measurements and transmission electron microscopy (TEM) examinations. From the transport measurements, the CO transition temperatures of all the three films are much higher than those of the bulk materials, showing that the film strain could enhance the CO transition. From TEM observations, many superlattice spots appear in the electron diffraction patterns taken from the films, indicating the appearance of the CO modulation structures at room temperature. The modulation vectors are determined to be (1/2, 0, 0) for STO (100), (1/2, 1/2, 1/2) for STO (110), and both (0, 1/2, 0) and (1/2, 1/2, 0) for LAO (100). It is shown that both the substrate orientation and the film strain have a great effect on the CO modulation structures. The CO state is much easier to appear in the compressive strain direction which is due to the Mn-O-Mn angle tilting.

  17. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics.

    PubMed

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K W

    2016-01-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr(3+), owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process. PMID:27339815

  18. Dielectric and piezoelectric properties of lead-free Ba0.85Ca0.15Ti0.9-xZr0.1CuxO3 ceramics synthesized by a hydrothermal method

    NASA Astrophysics Data System (ADS)

    Hunpratub, Sitchai; Phokha, Sumalin; Maensiri, Santi; Chindaprasirt, Prinya

    2016-04-01

    Ba0.85Ca0.15Ti0.9Zr0.1-xCuxO3 (BCTZC) nanopowders were synthesized using a hydrothermal method after which they were pressed into discs and sintered in air at 1300 °C for 3 h to form ceramic samples. The phase and microstructure of the powder and ceramic samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results indicated that the ceramic samples exhibited a tetragonal structure and that CuO, BaZrO3 or CaTiO3 impurity phases, which had been present in the powder samples, were not observed. The average grain sizes in the ceramic samples were found to be 17.0, 16.1, 20.0, 18.1 and 19.6 μm for Cu mole fractions x of 0.002, 0.004, 0.006, 0.008 and 0.01, respectively. The dielectric constants, ferroelectric hysteresis loops and piezoelectric charge coefficients of the BCZTC ceramic samples were also investigated. Optimum values for the relative dielectric constant (ɛ‧), tan δ and piezoelectric charge coefficient (d33) of the samples were 3830, 0.03 and 306 pC/N, respectively, in the Cu mole fraction samples with x = 0.002.

  19. AC Impedance Behavior of LaNi3.55Mn0.4Al0.3Co0.6Fe0.15 Hydrogen-Storage Alloy: Effect of Surface Area

    NASA Astrophysics Data System (ADS)

    Tliha, M.; Khaldi, C.; Lamloumi, J.

    2016-04-01

    The decrease of Cobalt content in alloy is very beneficial to reduce the production cost of the alloy, whereas the effect of Co on cycle life of the AB5-type hydrogen-storage alloys is extremely important. Therefore, it is interesting to investigate low-Co and/or Co-free AB5-type alloys in which Co was substituted by other elements. Iron is a key element in the development of low-Co AB5-type alloys. The aim of this work is to systematically investigate the effect of the real surface area on the all kinetic properties of a low-Co LaNi3.55Mn0.4Al0.3Co0.6Fe0.15 alloy under cycling using electrochemical impedance spectroscopy (EIS) technique. All kinetic properties of the electrode, such as exchange density, limiting current density, high-rate charge/discharge ability, cycle life time, electrocatalytic activity, and diffusion rate are related to the real surface area. During the EIS analysis, interestingly, we found that with increasing number of charge/discharge cycles, the metal hydride alloy powders undergo micro-cracking into smaller particles, and thus the real surface area of the alloy increases, which then influences the kinetic properties of the electrode reactions.

  20. In-situ raman microscopy of individual LiNi0.8Co0.15Al0.05O2 particles in the Li-ion battery composite cathode

    SciTech Connect

    Lei, Jinglei; McLarnon, Frank; Kostecki, Robert

    2004-10-01

    Kinetic characteristics of Li{sup +} intercalation/deintercalation into/from individual LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} particles in a composite cathode were studied in-situ using Raman microscopy during electrochemical charge-discharge in 1.2 M LiPF{sub 6}, ethylene carbonate (EC): ethyl-methyl carbonate (EMC), 3:7 by volume. Spectroscopic analysis of a cathode that was removed from a tested high-power Li-ion cell, which suffered substantial power and capacity loss, showed that the state of charge (SOC) of oxide particles on the cathode surface was highly non-uniform despite deep discharge of the Li-ion cell at the end of the test. In-situ monitoring of the SOC of selected oxide particles in the composite cathode in a sealed spectro-electrochemical cell revealed that the rate at which particles charge and discharge varied with time and location. The inconsistent kinetic behavior of individual oxide particles was attributed to degradation of the electronically conducting matrix in the composite cathode upon testing. These local micro-phenomena are responsible for the overall impedance rise of the cathode and contribute to the mechanism of lithium-ion cell failure.

  1. A study of surface film formation on LiNi0.8Co0.15Al0.05O2 cathodes u sing attenuated total reflection infrared spectroscopy

    SciTech Connect

    Song, S.-W.; Zhuang, G.V.; Ross Jr., P.N.

    2004-01-19

    The surface films formed on commercial LiNi0.8Co0.15Al0.05O2 cathodes (ATD Gen2) charged from 3.75V to 4.2V vs. Li/Li+ in EC:DEC - 1M LiPF6 were analyzed using ex-situ Fourier transform infrared spectroscopy (FTIR) with the attenuated total reflection (ATR) technique. A surface layer of Li2CO3 is present on the virgin cathode, probably from reaction of the active material with air during the cathode preparation procedure. The Li2CO3 layer disappeared even after soaking in the electrolyte, indicating that the layer dissolved into the electrolyte possibly even before potential cycling of the electrode. IR features only from the binder (PVdF) and a trace of polyamide from the Al current collector were observed on the surfaces of cathodes charged to below 4.2 V, i.e., no surface species from electrolyte oxidation. Some new IR features were, however, found on the cathode charged to 4.2 V and higher. An electrolyte oxidation product was observed that appeared to contain dicarbonyl anhydride and (poly)ester functionalities. The reaction appears to be an indirect electrochemical oxidation with overcharging (removal of > 0.6 Li ions) destabilizing oxygen in the oxide lattice resulting in oxygen transfer to the solvent molecules.

  2. Effect of injected spins with different polarized orientations on the vortex phase transition in La0.7Sr0.3MnO3/La1.85Sr0.15CuO4 heterostructure

    NASA Astrophysics Data System (ADS)

    Zhang, M. J.; Teng, M. L.; Hao, F. X.; Yin, Y. W.; Zeng, Z.; Li, X. G.

    2015-05-01

    The current-voltage (I-V) characteristics with spin injection were investigated for the epitaxial La0.7Sr0.3MnO3/La1.85Sr0.15CuO4 heterostructure rotated from H//c to H//ab in magnetic fields up to 14 T. It is found that all the I-V curves in various magnetic fields can be scaled with a three dimensional (3D) vortex glass model, and the spin injection can induce a better 3D scaling behavior, which is closely related to the decrease of the anisotropy parameter. A vortex phase diagram for the evolution of vortex glass transition field (Hg) and upper critical field (Hc2) indicates that both Hg and Hc2 are suppressed by spin injection, and this effect becomes more obvious in the case of H//ab, which probably originates from the different suppression on the superconducting pairing strength by different injected spins' orientations.

  3. Effect of Cr Addition on Wetting Behavior Between Cu and High-Temperature Zn-25Sn-0.15Al-0.1Ga- xCr Pb-Free Solder

    NASA Astrophysics Data System (ADS)

    Liu, Chin-Wei; Lin, Kwang-Lung

    2014-12-01

    In this study the effect of Cr content (0.02 wt.% to 0.2 wt.%) on the wetting interaction between high-temperature Zn-25Sn-0.15Al-0.1Ga- xCr Pb-free solders and Cu has been investigated using the wetting balance method. Differential scanning calorimetry (DSC) investigation showed that Cr addition reduces the liquidus temperature slightly while raising the solidus temperature. Flux-assisted wetting experiments were carried out at an immersion rate of 15 mm/s at 435°C. The results show that the shortest wetting time of around 0.7 s was achieved when 0.1 wt.% Cr was added, but the wetting force tends to decrease with the Cr content. Cr addition enhances the formation of interfacial Cu5Zn8 intermetallic compound (IMC) during air cooling, but the opposite effect was observed for water cooling. The results suggest that Cr addition depresses the formation of the Cu5Zn8 layer in liquid/solid reaction, but enhances the formation of the Cu5Zn8 layer in solid/solid reaction.

  4. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    PubMed Central

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-01-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process. PMID:27339815

  5. Tailoring Electrical Properties and the Structure Evolution of (Ba0.85Ca0.15)(Ti0.90Zr0.10)1- x Li4 x O3 Ceramics with Low Sintering Temperature

    NASA Astrophysics Data System (ADS)

    Chao, Xiaolian; Wang, Juanjuan; Xie, Xueke; Liang, Pengfei; Yang, Zupei

    2016-01-01

    The objective of this work is to lower the sintering temperature of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 (BCZT) ceramics without sacrificing their piezoelectric performance. Li2CO3 was used as sintering aid so that BCZT ceramics with low sintering temperature were fabricated by conventional solid-state sintering. The sintering temperature of the BCZT ceramics was greatly decreased from 1450°C to 1260°C by introducing Li2CO3. The ceramics with a Li2CO3 content of x = 0.02 demonstrated outstanding piezoelectric and dielectric properties: d 33 = 436 pC/N, k p = 56%, Q m = 86, ɛ r = 5185, tan δ = 0.017 and T c = 83°C. We explain the structural evolution in these ceramics through the growth mechanism of liquid-phase sintering, which includes 4 steps: (1) interface reaction in the initial state; (2) diffusion of Li2CO3 into BCZT grains; (3) densification by diffusion of CO2 through BCZT; and (4) improvement of properties by diffusion into the lattice of grain. As a result, Li2CO3 additive can effectively improve the piezoelectric properties of BCZT-based ceramics sintered at low temperatures.

  6. Enhanced piezoelectricity and photoluminescence in Dy-doped Ba0.85Ca0.15Ti0.9Zr0.1O3 lead-free multifunctional ceramics

    NASA Astrophysics Data System (ADS)

    Lei, Fengying; Jiang, Na; Luo, Lingling; Guo, Yongquan; Zheng, Qiaoji; Lin, Dunmin

    2015-12-01

    Lead-free multifunctional ceramics of Ba0.85Ca0.15Ti0.9Zr0.1O3-x mol% Dy have been prepared by an ordinary sintering method and the effects of Dy2O3 doping on structure, piezoelectric, ferroelectric and photoluminescent properties of the ceramics have been studied. The ceramics possess a single phase perovskite structure. The grain growth of the ceramics is prohibited and the ferroelectric-paraelectric phase transition at TC becomes more diffusive after the addition of Dy2O3. Dy2O3 doping improves the piezoelectricity of the ceramics and the optimal piezoelectric properties d33 = 335 pC/N is obtained at x = 0.5. The addition of 2 mol% Dy enhances the photoluminescent properties of the ceramics and strong emissions at ˜ 478 nm and ˜ 575 nm are observed. Our study shows that the ceramics with low Dy2O3 levels exhibit simultaneously the strong piezoelectricity, ferroelectricity and photoluminescence and may have a potential application in mechano-electro-optic integration and coupling device.

  7. Surface degradation of Li1-xNi0.80Co0.15Al0.05O2 cathodes: Correlating charge transfer impedance with surface phase transformations

    NASA Astrophysics Data System (ADS)

    Sallis, S.; Pereira, N.; Mukherjee, P.; Quackenbush, N. F.; Faenza, N.; Schlueter, C.; Lee, T.-L.; Yang, W. L.; Cosandey, F.; Amatucci, G. G.; Piper, L. F. J.

    2016-06-01

    The pronounced capacity fade in Ni-rich layered oxide lithium ion battery cathodes observed when cycling above 4.1 V (versus Li/Li+) is associated with a rise in impedance, which is thought to be due to either bulk structural fatigue or surface reactions with the electrolyte (or combination of both). Here, we examine the surface reactions at electrochemically stressed Li1-xNi0.8Co0.15Al0.05O2 binder-free powder electrodes with a combination of electrochemical impedance spectroscopy, spatially resolving electron microscopy, and spatially averaging X-ray spectroscopy techniques. We circumvent issues associated with cycling by holding our electrodes at high states of charge (4.1 V, 4.5 V, and 4.75 V) for extended periods and correlate charge-transfer impedance rises observed at high voltages with surface modifications retained in the discharged state (2.7 V). The surface modifications involve significant cation migration (and disorder) along with Ni and Co reduction, and can occur even in the absence of significant Li2CO3 and LiF. These data provide evidence that surface oxygen loss at the highest levels of Li+ extraction is driving the rise in impedance.

  8. Magnetocaloric effect and temperature coefficient of resistance of La0.85Ag0.15MnO3 epitaxial thin films obtained by polymer-assisted deposition

    NASA Astrophysics Data System (ADS)

    Cobas Acosta, R.; Muñoz-Pérez, S.; Cadogan, J. M.; Hutchison, W. D.; Ridgway, M. C.

    2014-07-01

    We report the magnetocaloric effects and temperature coefficient of resistance (TCR) of La0.85Ag0.15MnO3 epitaxial thin films grown on single-crystal substrates of LaAlO3 (001) and SrTiO3 (001) using the chemical solution approach of polymer-assisted deposition (PAD). The film thicknesses are in the range 30-35 nm. Magnetocaloric effects, with entropy changes of -2.14 J/kg.K, in the case of the LaAlO3 substrate and -2.72 J/kg.K for the SrTiO3 substrate, (corresponding to a magnetic field variation of 2T) were obtained at room temperature. The refrigeration capacity at this field variation reached large values of 125 J/kg and 216 J/kg, indicating that these films prepared by PAD have the potential for microcooling applications. The temperature coefficient of resistance has been calculated from the resistivity measurements. A maximum TCR value of 3.01 % K-1 was obtained at 309 K, which shows that these films also have potential as uncooled thermometers for bolometric applications.

  9. Transonic-Wind-Tunnel Tests of the Aerodynamic Characteristics of a 0.15-Scale Model of the North American Aviation 255-Inch Fin-Stabilized External Store, Coord No. AF-AM-4

    NASA Technical Reports Server (NTRS)

    Fischetti, Thomas L.

    1958-01-01

    An investigation has been made in the Langley 8-foot transonic tunnels on the aerodynamic characteristics of a 0.15-scale model of the North American Aviation 255-inch fin-stabilized external store over a maximum Mach number range of 0.60 to 1.2 and on the effects of mounting lugs, of fin orientation, of fin aspect ratio, and of fixed-transition. The Reynolds number (based on a body length of 37.50 inches) varied from 9.8 x 10(exp 6) to 13.1 x 10(exp 6). The results indicate that the static margin of the finned store at low lift coefficients was only 9 percent of body length at subsonic Mach numbers and was reduced to zero at a Mach number of 1.0, Increasing the fin aspect ratio from 1.82 to 2.41 increased the subsonic static margin to 18 percent and provided a minimum margin of 9 percent near a Mach number of l.O. Store mounting lugs or fin orientation had only small effects on the aerodynamic characteristics of the basic store.

  10. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    NASA Astrophysics Data System (ADS)

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-06-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process.

  11. Superconducting properties of single crystalline FeTe{sub 1-x}Se{sub x} (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50)

    SciTech Connect

    Sudesh,; Kumar, R.; Varma, G. D.

    2015-06-24

    In this paper we have grown single crystalline samples of Se-doped FeTe compound using self-flux technique and studied the structural and electrical transport properties of the as-grown crystals. The samples have been grown with compositions FeTe{sub 1-x}Se{sub x} (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50). The as-grown samples are then investigated for their structural and superconducting properties by means of X-ray diffraction and physical property measurements. The XRD results of powdered samples reveal a single (tetragonal) phase with space group symmetry P4/nmm for all the samples. The lattice parameters are observed to reduce with increase of Se-doping at Te-site. Highest H{sub c2}(0) (∼180 T) value has been observed for FeTe{sub 0.5}Se{sub 0.5} sample.

  12. Insights on the fundamental lithium storage behavior of all-solid-state lithium batteries containing the LiNi0.8Co0.15Al0.05O2 cathode and sulfide electrolyte

    NASA Astrophysics Data System (ADS)

    Peng, Gang; Yao, Xiayin; Wan, Hongli; Huang, Bingxin; Yin, Jingyun; Ding, Fei; Xu, Xiaoxiong

    2016-03-01

    An insightful study on the fundamental lithium storage behavior of all-solid-state lithium battery with a structure of LiNi0.8Co0.15Al0.05O2 (NCA)/Li10GeP2S12/Li-In is carried out in this work. The relationship between electrochemical performances and particle size, surface impurities and defects of the NCA positive material is systematically investigated. It is found that a ball-milling technique can decrease the particle size and remove surface impurities of the NCA cathode while also give rise to surface defects which could be recovered by a post-annealing process. The results indicate that the interfacial resistance between the NCA and Li10GeP2S12 is obviously decreased during the ball-milling followed by a post-annealing. Consequently, the discharge capacity of NCA in the NCA/Li10GeP2S12/Li-In solid-state battery is significantly enhanced, which exhibits a discharge capacity of 146 mAh g-1 at 25 °C.

  13. Magnetic and magnetocaloric properties of La{sub 0.85}(Na{sub 1−x}K{sub x}){sub 0.15}MnO{sub 3} ceramics produced by reactive spark plasma sintering

    SciTech Connect

    Regaieg, Y.; Sicard, L.; Ammar-Merah, S.; Monnier, J.; Koubaa, M.; Cheikhrouhou, A.

    2014-05-07

    La{sub 0.85}(Na{sub 1−x}K{sub x}){sub 0.15}MnO{sub 3} (0 ≤ x ≤ 1) ceramics were synthesized from the raw La(OH){sub 3}, NaOH, KOH, and MnO{sub 2} powders using Reactive Spark Plasma Sintering. All the compounds were obtained as pure, dense, and ultrafine grained pellets. The Rietveld refinement of the X-Ray powder diffraction shows that all our synthesized samples are single phase and crystallize in the distorted rhombohedral system with R-3c space group. The thermal variation of their magnetization under a magnetic applied field of 50 mT shows a paramagnetic to ferromagnetic transition at a Curie temperature very close to room temperature. The magnetic entropy change, deduced from magnetization measurements versus magnetic applied field up to 5 T at several temperatures exhibits a maximum |ΔS{sub M}|{sub max} which slightly increases with increasing K content. The relative cooling power values, inferred from the |ΔS{sub M}| vs T peak broadening, vary slightly with the potassium content, reaching, values between 316 and 289 Jkg{sup −1}, in an applied magnetic field of 5 T, when x increases from 0 to 1. Technically, these large values make the prepared materials very promising for domestic magnetic refrigeration.

  14. Preparation of Superconducting Magnetostatic Wave (MSW) Devices Consisting of High-Tc Superconductor (HTS)/Perovskite-Type Manganite Heterostructures: Application of Pr0.85Ca0.15MnO3 as a MSW Waveguide

    NASA Astrophysics Data System (ADS)

    Hontsu, Shigeki; Sakatani, Tomotaka; Nishikawa, Hiroaki; Nakamori, Masaya; Fujimaki, Akira; Kawai, Tomoji

    2001-10-01

    Electric and magnetic properties of Pr0.85Ca0.15MnO3 (PCMO) have been investigated in order to apply the material to superconducting microwave devices. PCMO films are prepared on (100) surfaces of a (La0.3Sr0.7) (Al0.65Ta0.35)O3 (LSAT) single crystal by a pulsed laser deposition technique. By optimizing the deposition conditions, c-axis oriented PCMO epitaxial films are obtained. The Curie temperature (TC) of these PCMO films is approximately 130 K. The remanent magnetization and the coercive field for the sample measured at 77 K are about 240 G and 250 Oe, respectively. The relative dielectric constant and loss tangent are significantly decreased below TC and are about 13 and 6×10-3 at 30 K, respectively. Furthermore, magnetostatic wave (MSW) excitation is observed in a PCMO film by constructing a band elimination filter based on the MSW mode with YBa2Cu3O7-δ(YBCO)/PCMO heterostructure. These results indicate that PCMO is applicable for magnetic microwave devices including MSW devices with superconducting thin films.

  15. Archimedean solidlike superconducting framework in phase-separated K0.8F e1.6 +xS e2(0 ≤x ≤0.15 )

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Cai, Y.; Wang, Z. W.; Ma, C.; Chen, Z.; Yang, H. X.; Tian, H. F.; Li, J. Q.

    2015-02-01

    The superconducting (SC) phase in phase-separated (PS) K0.8F e1.6 +xS e2(0 ≤x ≤0.15 ) materials is found to crystallize on Archimedean solidlike frameworks, and this structural feature originates from a spinodal phase separation (SPS) at around Ts≈540 K , depending slightly on the Fe concentration, as revealed by in situ heating TEM observations and shown in a phase diagram. Two stable phases in K0.8F e1.6 +xS e2 are demonstrated to be the SC K0.5F e2S e2 and antiferromagnetic (AFM) K0.8F e1.6S e2 . The spinodal waves go along the systematic [113 ] direction and result in notable lamellar structure as illustrated by strain-field theoretical simulations. The three-dimensional SC framework is constructed with hollow truncated octahedron similar to that discussed for Archimedean solids. Based on this structural model, we can efficiently calculate the volume fraction of the SC phase in this type of PS SC material.

  16. Anisotropy of electric resistance and upper critical field in magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4

    NASA Astrophysics Data System (ADS)

    Terekhov, A. V.; Zolochevskii, I. V.; Khristenko, E. V.; Ishchenko, L. A.; Bezuglyi, E. V.; Zaleski, A.; Khlybov, E. P.; Lachenkov, S. A.

    2016-05-01

    We have measured temperature dependencies of the electric resistance R and upper critical magnetic field Hc2 of a magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4. The measurements were made for different angles φ of the magnetic field inclination to the direction of measuring current and revealed strong anisotropy of the behavior of R(T) and the values of Hc2(T). By using the Werthamer-Gelfand-Hohenberg theory, we determined the Maki parameter α and the parameter of the spin-orbital interaction. For φ =0∘ and 90° both parameters are close to zero, thus the magnitude of Hc2(0) ≈ 38 kOe is basically limited by the orbital effect. At φ =45∘ , a large value of α = 4.2 indicates dominating role of the spin-paramagnetic effect in the suppression of Hc2(0) down to 8.8 kOe. We suggest that such behavior of R(T) and Hc2(T) is caused by internal magnetism of the Dy atoms which may strongly depend on the magnetic field orientation.

  17. Temperature evolution of superparamagnetic clusters in single-crystal La0.85Sr0.15CoO3 characterized by nonlinear magnetic ac response and neutron depolarization

    NASA Astrophysics Data System (ADS)

    Lazuta, A. V.; Ryzhov, V. A.; Runov, V. V.; Khavronin, V. P.; Deriglazov, V. V.

    2015-07-01

    The representative measurements of the second harmonic in ac magnetization complemented by neutron depolarization have been performed for single-crystal La0.85Sr0.15CoO3 in the temperature range 97 K

  18. Atomic resolution imaging of oxygen atoms close to heavy atoms by HRTEM and ED, using the superconductor SmFeAsO0.85F0.15 as an example.

    PubMed

    Wang, Yumei; Ge, Binghui; Che, Guangcan

    2015-04-01

    Imaging of light atoms has always been a challenge in high-resolution electron microscopy. Image resolution is mainly limited by lens aberrations, especially the spherical aberration of the objective lens. Image deconvolution could correct for the image distortion by lens aberrations and restore the structure projection, the resolution of which is limited by the information limit of the microscope. Electron diffraction unrestricted by lens aberrations could overcome this resolution limit. Here we show a combination of electron diffraction and image deconvolution to reveal simultaneously the atomic columns of O and considerably heavier Sm at a very close distance (1.17 Å) in iron-based superconductor SmFeAsO0.85F0.15 using a conventional 200 kV electron microscope. The approach used here, starting from an image and an electron diffraction pattern, has an advantage for those radiation-sensitive samples. Besides, it can be applied to simultaneously imaging light and heavy atoms, even though they have a big difference in atomic number and a much smaller atomic distance than the microscope resolution. PMID:25635603

  19. A microwave-assisted sol-gel Pechini method for the synthesis of BaCe{sub 0.65}Zr{sub 0.20}Y{sub 0.15}O{sub 3-{delta}} powders

    SciTech Connect

    Barison, S.; Fabrizio, M.; Fasolin, S.; Montagner, F.; Mortalo, C.

    2010-09-15

    In this work, BaCe{sub 0.65}Zr{sub 0.20}Y{sub 0.15}O{sub 3-{delta}} powders with a perovskite-type structure were successfully synthesized by a microwave-assisted sol-gel Pechini method (SGP). By comparison, powders having the same nominal stoichiometry were also prepared without the microwave assistance. For the syntheses, nitrates were used as metal precursors, and ethylenediaminetetraacetic acid and ethylene glycol were used as complexing and polymerizing agents, respectively. An extensive structural and morphological investigation by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) has been performed. Moreover, in order to check the phase transitions, simultaneous thermogravimetric and differential thermal analyses were (TG-DTA) performed on gels. With respect to the conventional Pechini method, the microwave-assisted process guaranteed a faster, energy-saving procedure for obtaining single-phase nanopowders of high purity. Moreover, a significant increase in pellet densities was achieved owing to a higher grain coalescence.

  20. Optimized structure stability and electrochemical performance of LiNi0.8Co0.15Al0.05O2 by sputtering nanoscale ZnO film

    NASA Astrophysics Data System (ADS)

    Lai, Yan-Qing; Xu, Ming; Zhang, Zhi-An; Gao, Chun-Hui; Wang, Peng; Yu, Zi-Yang

    2016-03-01

    LiNi0.8Co0.15Al0.05O2 (NCA) is one of the most promising cathode material for lithium-ion batteries (LIBs) in electric vehicles, which is successfully adopted in Tesla. However, the dissolution of the cation into the electrolyte is still a one of the major challenges (fading capacity and poor cyclability, etc.) presented in pristine NCA. Herein, a homogeneous nanoscale ZnO film is directly sputtered on the surface of NCA electrode via the magnetron sputtering (MS). This ZnO film is evidenced by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results clearly demonstrate that ZnO film is fully and uniformly covered on the NCA electrodes. After 90 cycles at 1.0C, the optimized MS-2min coated NCA electrode delivers much higher discharge capacity with 169 mAh g-1 than that of the pristine NCA electrode with 127 mAh g-1. In addition, the discharge capacity also reaches 166 mAh g-1 at 3.0C, as compared to that of 125 mAh g-1 for the pristine electrode. The improved electrochemical performance can be ascribed to the superiority of the MS ZnO film that reduce charge transfer resistance and protect the NCA electrode from cation dissolution.

  1. Structural, thermal and microstructural studies of the proton conductor BaCe0.7Zr0.1Y0.05Zn0.15O3 for IT-SOFCs

    NASA Astrophysics Data System (ADS)

    Hossain, S.; Radenahmad, N.; Zaini, J. H.; Begum, F.; Azad, A. K.

    2016-03-01

    The specimen of BaCe0.7Zr0.1Y0.05Zn0.15O3, a perovskite-type electrolyte, has been synthesized for application in an anode-supported protonic solid oxide fuel cell by the conventional solid state reaction in air at 1200°C for 12 hours. Structural and thermal characterization has been performed using room temperature X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA). Rietveld analysis of the XRD data has been analyzed by FullProf program and confirmed the single phase of the sample with an orthorhombic crystal structure in the Pbnm space group. To understand the temperature dependent behaviour TG/DTA scan of the precursor was recorded. The TG/DTA scan was performed under constant flow of Argon which exhibits a gradual weight loss up to 900oC. The SEM image of the pellet surface of the sample shows that the sample sintered at 1200oC was dense and suitable to use as electrolyte in solid oxide fuel cells (SOFCs).

  2. Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS.

    PubMed

    Fatemi, R; Skabelin, A V; Burkert, V D; Crabb, D; De Vita, R; Kuhn, S E; Minehart, R; Adams, G; Anciant, E; Anghinolfi, M; Asavapibhop, B; Audit, G; Auger, T; Avakian, H; Bagdasaryan, H; Ball, J P; Barrow, S; Battaglieri, M; Beard, K; Bektasoglu, M; Bellis, M; Bertozzi, W; Bianchi, N; Biselli, A S; Boiarinov, S; Bonner, B E; Bosted, P E; Bouchigny, S; Bradford, R; Branford, D; Brooks, W K; Butuceanu, C; Calarco, J R; Carman, D S; Carnahan, B; Cetina, C; Ciciani, L; Clark, R; Cole, P L; Coleman, A; Connelly, J; Cords, D; Corvisiero, P; Crannell, H; Cummings, J P; De Sanctis, E; Degtyarenko, P V; Denizli, H; Dennis, L; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Eckhause, M; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Empl, A; Eugenio, P; Farhi, L; Feuerbach, R J; Freyberger, A; Ficenec, J; Forest, T A; Frolov, V; Funsten, H; Gaff, S J; Garçon, M; Gavalian, G; Gilad, S; Gilfoyle, G P; Giovanetti, K L; Girard, P; Gordon, C I O; Griffioen, K A; Guidal, M; Guillo, M; Guo, L; Gyurjyan, V; Hadjidakis, C; Hancock, D; Hardie, J; Heddle, D; Heimberg, P; Hersman, F W; Hicks, K; Hicks, R S; Holtrop, M; Hu, J; Hyde-Wright, C E; Ilieva, Y; Ito, M M; Jenkins, D; Joo, K; Keith, C; Kelley, J H; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Klusman, M; Kossov, M; Koubarovski, V; Kramer, L H; Kuang, Y; Kuhn, J; Lachniet, J; Laget, J M; Lawrence, D; Li, Ji; Livingston, K; Longhi, A; Lukashin, K; Major, W; Manak, J J; Marchand, C; McAleer, S; McNabb, J W C; Mecking, B A; Mehrabyan, S; Mestayer, M D; Meyer, C A; Mikhailov, K; Mirazita, M; Miskimen, R; Morand, L; Morrow, S A; Muccifora, V; Mueller, J; Mutchler, G S; Napolitano, J; Nasseripour, R; Nelson, S O; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'Brien, J T; O'Rielly, G V; Osipenko, M; Park, K; Pasyuk, E; Peterson, G; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Rock, S E; Ronchetti, F; Rossi, P; Rowntree, D; Rubin, P D; Sabatié, F; Sabourov, K; Salgado, C; Santoro, J P; Sapunenko, V; Sargsyan, M; Schumacher, R A; Seely, M; Serov, V S; Sharabian, Y G; Shaw, J; Simionatto, S; Smith, E S; Smith, T; Smith, L C; Sober, D I; Sorrel, L; Spraker, M; Stavinsky, A; Stepanyan, S; Stoler, P; Strauch, S; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Todor, L; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weller, H; Weygand, D P; Whisnant, C S; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zhang, B; Zhao, J; Zhou, Z

    2003-11-28

    Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value. PMID:14683231

  3. Ni-induced local distortions in La1.85Sr0.15Cu1-yNiyO4 and their relevance to Tc suppression: An angular-resolved XAFS study

    NASA Astrophysics Data System (ADS)

    Haskel, Daniel; Stern, Edward A.; Polinger, Victor; Dogan, Fatih

    2001-09-01

    We present results from angular-resolved x-ray-absorption fine-structure (XAFS) measurements at the Ni, La, and Sr K edges of oriented powders of La1.85Sr0.15Cu1-yNiyO4, with y=0.01, 0.03, 0.06. A special magnetic alignment procedure allowed us to measure pure ĉ- and ab-oriented XAFS at the Ni K edge in identical fluorescence geometries. Both the x-ray-absorption near-edge structure and the XAFS unequivocally show that the NiO6 octahedra are contracted along the c axis by ~0.32 Å relative to CuO6 octahedra while the in-plane distances of NiO6 and CuO6 octahedra are the same within 0.01 Å. The NiO6 octahedral contraction drives the average ĉ axis contraction measured by diffraction with increasing content of Ni. The local ĉ axis shows strong spatial fluctuations, due to the different NiO6 and CuO6 octahedral configurations and the stronger bonding of a La3+ ion than a Sr2+ ion to the O(2) apical oxygens of such octahedra. We discuss the relevance of these findings to the mechanisms of loss of superconductivity at y~0.03 and hole localization above y~0.05 by Ni dopants.

  4. A cm scale electret-based electrostatic wind turbine for low-speed energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Perez, M.; Boisseau, S.; Gasnier, P.; Willemin, J.; Geisler, M.; Reboud, J. L.

    2016-04-01

    This paper presents a small-scale airflow energy harvester built on an axial turbine architecture and exploiting an electret-based electrostatic converter. When the airflow velocity is high enough, the windmill starts rotating and creates a periodic relative motion between a stator and a rotor which induces variations of capacitance. These ones are directly converted into electricity thanks to the use of Teflon electrets charged at -1400 V which polarize the variable capacitors. We focus our study on a 4-blade axial turbine with a diameter of D = 40 mm, a depth of W = 10 mm, for a total volume of 12.6 cm3. This windmill has been tested with various blade angles and different types of electrostatic converters and output powers up to 90 μW at 1.5 m s-1 (7.5 μW cm-3) and 1.8 mW at 10 m s-1 (111 μW cm-3) have been obtained so far. The coefficient of power reaches C p = 5.8% and among the small-scale airflow energy harvesters previously reported, this one has the lowest cut-in speed (1.5 m s-1).

  5. Operation of a Five-Stage 40,000-CM(2)-Area Insulator Stack at 158 KV/CM

    SciTech Connect

    Anderson R.A.; Clark, Robert E.; Corcoran, P.A.; Douglas, John W.; Gilliland, T.L.; Horry, M.L.; Hughes, Thomas P.; Ives, H.C.; Long, F.W.; Martin, T.H.; McDaniel, D.H.; Milton, Osborne; Mostrom, Michael A.; Seamen, J.F.; Shoup, R.W.; Smith, I.D.; Smith, J.W.; Spielman, R.B.; Struve, K.W.; Stygar, W.A.; Vogtlin, George E.; Wagoner, T.C.; Yamamoto, Osamu

    1999-06-30

    We have demonstrated successful operation of a 3.35- m-diameter insulator stack at 158 kV/cm on five consecutive Z-accelerator shots. The stack consisted of five +45°-profile 5.715-cm-thick cross-linked-polystyrene (Rexolite- 1422) insulator rings, and four anodized- aluminum grading rings shaped to reduce the field at cathode triple junctions. The width of the voltage pulse at 89% of peak was 32 ns. We compare this result to a new empirical flashover relation developed from previous small-insulator experiments conducted with flat unanodized electrodes. The relation predicts a 50% flashover probability for a Rexolite insulator during an applied voltage pulse when Emaxe-0.27/d(teffC)1/10 = 224, where Emax is the peak mean electric field (kV/cm), d is the insulator thickness (cm), teff is the effective pulse width (ps), and C is the insulator circumference (cm). We find the Z stack can be operated at a stress at least 19% higher than predicted. This result, and previous experiments conducted by Vogtlin, suggest anodized electrodes with geometries that reduce the field at both anode and cathode triple junctions would improve the flashover strength of +45° insulators.

  6. The Complexity and Challenges of the ICD-9-CM to ICD-10-CM Transition in Emergency Departments

    PubMed Central

    Krive, Jacob; Patel, Mahatkumar; Gehm, Lisa; Mackey, Mark; Kulstad, Erik; Li, Jianrong ‘John’; Lussier, Yves A.; Boyd, Andrew D.

    2015-01-01

    Beginning October 2015, the Center for Medicare and Medicaid Services (CMS) will require medical providers to utilize the vastly expanded ICD-10-CM system. Despite wide availability of information and mapping tools for the next generation of the ICD classification system, some of the challenges associated with transition from ICD-9-CM to ICD-10-CM are not well understood. To quantify the challenges faced by emergency physicians, we analyzed a subset of a 2010 Illinois Medicaid database of emergency department ICD-9-CM codes, seeking to determine the accuracy of existing mapping tools in order to better prepare emergency physicians for the change to the expanded ICD-10-CM system. We found that 27% of 1,830 codes represented convoluted multidirectional mappings. We then analyzed the convoluted transitions and found 8% of total visit encounters (23% of the convoluted transitions) were clinically incorrect. The ambiguity and inaccuracy of these mappings may impact the work flow associated with the translation process and affect the potential mapping between ICD codes and CPT (Current Procedural Codes) codes, which determine physician reimbursement. PMID:25863652

  7. A quantile count model of water depth constraints on Cape Sable seaside sparrows

    USGS Publications Warehouse

    Cade, B.S.; Dong, Q.

    2008-01-01

    1. A quantile regression model for counts of breeding Cape Sable seaside sparrows Ammodramus maritimus mirabilis (L.) as a function of water depth and previous year abundance was developed based on extensive surveys, 1992-2005, in the Florida Everglades. The quantile count model extends linear quantile regression methods to discrete response variables, providing a flexible alternative to discrete parametric distributional models, e.g. Poisson, negative binomial and their zero-inflated counterparts. 2. Estimates from our multiplicative model demonstrated that negative effects of increasing water depth in breeding habitat on sparrow numbers were dependent on recent occupation history. Upper 10th percentiles of counts (one to three sparrows) decreased with increasing water depth from 0 to 30 cm when sites were not occupied in previous years. However, upper 40th percentiles of counts (one to six sparrows) decreased with increasing water depth for sites occupied in previous years. 3. Greatest decreases (-50% to -83%) in upper quantiles of sparrow counts occurred as water depths increased from 0 to 15 cm when previous year counts were 1, but a small proportion of sites (5-10%) held at least one sparrow even as water depths increased to 20 or 30 cm. 4. A zero-inflated Poisson regression model provided estimates of conditional means that also decreased with increasing water depth but rates of change were lower and decreased with increasing previous year counts compared to the quantile count model. Quantiles computed for the zero-inflated Poisson model enhanced interpretation of this model but had greater lack-of-fit for water depths > 0 cm and previous year counts 1, conditions where the negative effect of water depths were readily apparent and fitted better with the quantile count model.

  8. Retrofit and acceptance test of 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.

    1981-01-01

    Six 30 cm mercury thrusters were modified to the J-series design and evaluated using standardized test procedures. The thruster performance meets the design objectives (lifetime objective requires verification), and documentation (drawings, etc.) for the design is completed and upgraded. The retrofit modifications are described and the test data for the modifications are presented and discussed.

  9. Search for Cm-248 in the early solar system

    NASA Technical Reports Server (NTRS)

    Lavielle, B.; Marti, K.; Pellas, P.; Perron, C.

    1992-01-01

    Possible evidence for the presence of Cm-248 in the early solar system was reported from fission gas studies (Rao and Gopalan, 1973) and recently from studies of very high nuclear track densities (not less than 5 x 10 exp 8/sq cm) in the merrillite of the H4 chondrite Forest Vale (F.V.) (Pellas et al., 1987). We report here an analysis of the isotopic abundances of xenon in F.V. phosphates and results of track studies in phosphate/pyroxene contacts. The fission xenon isotopic signature clearly identifies Pu-244 as the extinct progenitor. We calculate an upper limit Cm-248/Pu-244 to be less than 0.0015 at the beginning of Xe retention in F.V. phosphates. This corresponds to an upper limit of the ratio Cm-248/U-235 of not greater than 5 x 10 exp -5 further constraining the evidence for any late addition of freshly synthesized actinide elements just prior to solar system formation. The fission track density observed after annealing the phosphates at 290C (1 hr, which essentially erases spallation recoil tracks) is also in agreement with the Pu-244 abundance inferred from fission Xe. The spallation recoil tracks produced during the 76 Ma cosmic-ray exposure account for the very high track density in merrillites.

  10. Adaptation of California Measure of Mental Motivation-CM3

    ERIC Educational Resources Information Center

    Özdemir, Hasan Fehmi; Demirtasli, Nükhet Çikrikçi

    2015-01-01

    Education without doubt, plays a vital role for individuals to gain the essential personal traits of the 21st century, also known as "knowledge age". One of the most important skills among these fundamental qualities which the individuals should be equipped with is critical thinking. California Measure of Mental Motivation-CM3 was…

  11. Cosmological constraints from 21cm surveys after reionization

    SciTech Connect

    Visbal, Eli; Loeb, Abraham; Wyithe, Stuart E-mail: aloeb@cfa.harvard.edu

    2009-10-01

    21cm emission from residual neutral hydrogen after the epoch of reionization can be used to trace the cosmological power spectrum of density fluctuations. Using a Fisher matrix formulation, we provide a detailed forecast of the constraints on cosmological parameters that are achievable with this probe. We consider two designs: a scaled-up version of the MWA observatory as well as a Fast Fourier Transform Telescope. We find that 21cm observations dedicated to post-reionization redshifts may yield significantly better constraints than next generation Cosmic Microwave Background (CMB) experiments. We find the constraints on Ω{sub Λ}, Ω{sub m}h{sup 2}, and Ω{sub ν}h{sup 2} to be the strongest, each improved by at least an order of magnitude over the Planck CMB satellite alone for both designs. Our results do not depend as strongly on uncertainties in the astrophysics associated with the ionization of hydrogen as similar 21cm surveys during the epoch of reionization. However, we find that modulation of the 21cm power spectrum from the ionizing background could potentially degrade constraints on the spectral index of the primordial power spectrum and its running by more than an order of magnitude. Our results also depend strongly on the maximum wavenumber of the power spectrum which can be used due to non-linearities.

  12. The 21 cm signature of a cosmic string loop

    SciTech Connect

    Pagano, Michael; Brandenberger, Robert E-mail: rhb@physics.mcgill.ca

    2012-05-01

    Cosmic string loops lead to nonlinear baryon overdensities at early times, even before the time which in the standard LCDM model corresponds to the time of reionization. These overdense structures lead to signals in 21 cm redshift surveys at large redshifts. In this paper, we calculate the amplitude and shape of the string loop-induced 21 cm brightness temperature. We find that a string loop leads to a roughly elliptical region in redshift space with extra 21 cm emission. The excess brightness temperature for strings with a tension close to the current upper bound can be as high as 1deg K for string loops generated at early cosmological times (times comparable to the time of equal matter and radiation) and observed at a redshift of z+1 = 30. The angular extent of these predicted 'bright spots' is x{sup '}. These signals should be detectable in upcoming high redshift 21 cm surveys. We also discuss the application of our results to global monopoles and primordial black holes.

  13. Calorimetric determination of kQ factors for NE 2561 and NE 2571 ionization chambers in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV photons

    NASA Astrophysics Data System (ADS)

    Krauss, Achim; Kapsch, Ralf-Peter

    2007-10-01

    The relative uncertainty of the ionometric determination of the absorbed dose to water, Dw, in the reference dosimetry of high-energy photon beams is in the order of 1.5% and is dominated by the uncertainty of the calculated chamber- and energy-dependent correction factors kQ. In the present investigation, kQ values were determined experimentally in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV bremsstrahlung by means of a water calorimeter operated at 4 °C. Ionization chambers of the types NE 2561 and NE 2571 were calibrated directly in the water phantom of the calorimeter. The measurements were carried out at the linear accelerator of the Physikalisch-Technische Bundesanstalt. It is shown that the kQ factor of a single ionization chamber can be measured with a standard uncertainty of less than 0.3%. No significant variations of kQ were found for the different lateral sizes of the radiation fields used in this investigation.

  14. Electronic and magnetic properties of Am and Cm

    SciTech Connect

    Edelstein, N.

    1985-02-01

    A review of the present status of the analyses of the optical spectra of Am and Cm in various oxidation states is given. From these analyses, the magnetic properties of the ground states of these ions can be determined. These predicted values are compared with the various magnetic measurements available.

  15. The Ecological Response of Carex lasiocarpa Community in the Riparian Wetlands to the Environmental Gradient of Water Depth in Sanjiang Plain, Northeast China

    PubMed Central

    Luan, Zhaoqing; Wang, Zhongxin; Yan, Dandan; Liu, Guihua; Xu, Yingying

    2013-01-01

    The response of Carex lasiocarpa in riparian wetlands in Sanjiang Plain to the environmental gradient of water depth was analyzed by using the Gaussian Model based on the biomass and average height data, and the ecological water-depth amplitude of Carex lasiocarpa was derived. The results indicated that the optimum ecological water-depth amplitude of Carex lasiocarpa based on biomass was [13.45 cm, 29.78 cm], while the optimum ecological water-depth amplitude of Carex lasiocarpa based on average height was [2.31 cm, 40.11 cm]. The intersection of the ecological water-depth amplitudes based on biomass and height confirmed that the optimum ecological water-depth amplitude of Carex lasiocarpa was [13.45 cm, 29.78 cm] and the optimist growing water-depth of Carex lasiocarpa was 21.4 cm. The TWINSPAN, a polythetic and divisive classification tool, was used to classify the wetland ecological series into 6 associations. Result of TWINSPAN matrix classification reflected an obvious environmental gradient in these associations: water-depth gradient. The relation of biodiversity of Carex lasiocarpa community and water depth was determined by calculating the diversity index of each association. PMID:24065874

  16. Visual Cues for Enhancing Depth Perception.

    ERIC Educational Resources Information Center

    O'Donnell, L. M.; Smith, A. J.

    1994-01-01

    This article describes the physiological mechanisms involved in three-dimensional depth perception and presents a variety of distance and depth cues and strategies for detecting and estimating curbs and steps for individuals with impaired vision. (Author/DB)

  17. Maribo—A new CM fall from Denmark

    NASA Astrophysics Data System (ADS)

    Haack, Henning; Grau, Thomas; Bischoff, Addi; Horstmann, Marian; Wasson, John; Sørensen, Anton; Laubenstein, Matthias; Ott, Ulrich; Palme, Herbert; Gellissen, Marko; Greenwood, Richard C.; Pearson, Victoria K.; Franchi, Ian A.; Gabelica, Zelimir; Schmitt-Kopplin, Philippe

    2012-01-01

    Maribo is a new Danish CM chondrite, which fell on January 17, 2009, at 19:08:28 CET. The fall was observed by many eye witnesses and recorded by a surveillance camera, an all sky camera, a few seismic stations, and by meteor radar observatories in Germany. A single fragment of Maribo with a dry weight of 25.8 g was found on March 4, 2009. The coarse-grained components in Maribo include chondrules, fine-grained olivine aggregates, large isolated lithic clasts, metals, and mineral fragments (often olivine), and rare Ca,Al-rich inclusions. The components are typically rimmed by fine-grained dust mantles. The matrix includes abundant dust rimmed fragments of tochilinite with a layered, fishbone-like texture, tochilinite-cronstedtite intergrowths, sulfides, metals, and carbonates often intergrown with tochilinite. The oxygen isotopic composition: (δ17O = -1.27‰; δ18O = 4.96‰; Δ17O = -3.85‰) plots at the edge of the CM field, close to the CCAM line. The very low Δ17O and the presence of unaltered components suggest that Maribo is among the least altered CM chondrites. The bulk chemistry of Maribo is typical of CM chondrites. Trapped noble gases are similar in abundance and isotopic composition to other CM chondrites, stepwise heating data indicating the presence of gas components hosted by presolar diamond and silicon carbide. The organics in Maribo include components also seen in Murchison as well as nitrogen-rich components unique to Maribo.

  18. Uterine caliper and depth gauge

    DOEpatents

    King, Loyd L.; Wheeler, Robert G.; Fish, Thomas M.

    1977-01-01

    A uterine caliper and sound consisting of an elongated body having outwardly biased resilient caliper wings and a spring-loaded slidable cervical stop. A slide on the body is operatively connected to the wings by a monofilament and operates with respect to a first scale on the body as a width indicator. A rod extending longitudinally on the body is connected to the cervical stop and cooperates with a second scale on the body as a depth indicator. The instrument can be positioned to measure the distance from the outer cervical ostium to the fundus, as read on said second scale. The wings may be allowed to open by moving the slide, and when the wings engage the utero-tubal junctions, the width may be read on said first scale. By adjustment of the caliper wings the instrument may be retracted until the resistance of the inner ostium of the cervix is felt, enabling the length of the cervical canal to be read directly by the position of the longitudinal indicator rod with respect to said second scale. The instrument may be employed to measure the width of the uterine cavity at any position between the inner ostium of the cervix and the fundus.

  19. The Paris meteorite, the least altered CM chondrite so far

    NASA Astrophysics Data System (ADS)

    Hewins, Roger H.; Bourot-Denise, Michèle; Zanda, Brigitte; Leroux, Hugues; Barrat, Jean-Alix; Humayun, Munir; Göpel, Christa; Greenwood, Richard C.; Franchi, Ian A.; Pont, Sylvain; Lorand, Jean-Pierre; Cournède, Cécile; Gattacceca, Jérôme; Rochette, Pierre; Kuga, Maïa; Marrocchi, Yves; Marty, Bernard

    2014-01-01

    The Paris chondrite provides an excellent opportunity to study CM chondrules and refractory inclusions in a more pristine state than currently possible from other CMs, and to investigate the earliest stages of aqueous alteration captured within a single CM bulk composition. It was found in the effects of a former colonial mining engineer and may have been an observed fall. The texture, mineralogy, petrography, magnetic properties and chemical and isotopic compositions are consistent with classification as a CM2 chondrite. There are ∼45 vol.% high-temperature components mainly Type I chondrules (with olivine mostly Fa0-2, mean Fa0.9) with granular textures because of low mesostasis abundances. Type II chondrules contain olivine Fa7 to Fa76. These are dominantly of Type IIA, but there are IIAB and IIB chondrules, II(A)B chondrules with minor highly ferroan olivine, and IIA(C) with augite as the only pyroxene. The refractory inclusions in Paris are amoeboid olivine aggregates (AOAs) and fine-grained spinel-rich Ca-Al-rich inclusions (CAIs). The CAI phases formed in the sequence hibonite, perovskite, grossite, spinel, gehlenite, anorthite, diopside/fassaite and forsterite. The most refractory phases are embedded in spinel, which also occurs as massive nodules. Refractory metal nuggets are found in many CAI and refractory platinum group element abundances (PGE) decrease following the observed condensation sequences of their host phases. Mn-Cr isotope measurements of mineral separates from Paris define a regression line with a slope of 53Mn/55Mn = (5.76 ± 0.76) × 106. If we interpret Cr isotopic systematics as dating Paris components, particularly the chondrules, the age is 4566.44 ± 0.66 Myr, which is close to the age of CAI and puts new constraints on the early evolution of the solar system. Eleven individual Paris samples define an O isotope mixing line that passes through CM2 and CO3 falls and indicates that Paris is a very fresh sample, with variation explained

  20. [Effects of sowing depth on seedling traits and root characteristics of summer maize].

    PubMed

    Cao, Hui-ying; Wang, Ding-bo; Shi, Jian-guo; Zhu, Kun-lun; Dong, Shu-ting; Liu, Peng; Zhao, Bin; Zhang, Ji-wang

    2015-08-01

    Two summer maize hybrids, Zhengdan 958 (ZD958) and Xianyu 335 (XY335), were used as experimental materials. 4 sowing depths (3, 5, 7 and 9 cm) and uneven sowing depth (CK) were designed under sand culture and field experiments to investigate the effects of sowing depth on seedling traits and root characteristics of summer maize. The results showed that the seedling emergence rate gradually decreased and seedling emergence time gradually lengthened as the sowing depth increased. Compared with the sowing depth of 3 cm, the seedling emergence rates of ZD958 and XY335 sown at the depth of 9 cm were reduced by 9.4% and 11.8%, respectively, and the seedling emergence duration was prolonged 1.5 d. With the increasing sowing depth, the seedling length and uniformity decreased significantly, the mesocotyl length increased significantly, while the coleoptile length had no significant difference; the primary radicle length gradually decreased, the total length of secondary radicle gradually increased, and the total root length had no significant difference; the total dry mass of seedling and mesocotyl increased significantly, and the total root dry mass had no significant difference. With the increasing sowing depth, the soluble sugar content in each part of seedling increased and the amount of nutritional consumption of germinating seeds increased, the seedling root growth rate increased, but the root activity decreased, and the number of total nodal root and nodal layers increased. With the increasing sowing depth, harvested ears per unit area were reduced by decreased seedling emergence rate and seedling vigor, thus influenced the yield. In addition, uniform sowing depth could improve the canopy uniformity and relative characteristics, then increase the yield. PMID:26685603

  1. Depth distribution of glyphosate and AMPA under diferent tillage system and soils in long-term experiments

    NASA Astrophysics Data System (ADS)

    Aparicio, Virginia; Costa, Jose Luis; De Geronimo, Eduardo

    2016-04-01

    Glyphosate (N-(phosphonomethyl glycine) is a post-emergence, non-selective, foliar herbicide. Around 200 million liters of this herbicide are applied every year in Argentina, where the main agricultural practice is no-till (NT), accounting for 78 % of the cultivated land. In this work, we studied the depth distribution of glyphosate in long-term experiments (more than 15 years) at different locations under NT and conventional tillage (CT). Samples from 0-2, 2-5, 5-10, 10-15, and 15-20 cm depth with four replication and two treatments NT CT at three locations: Balcarce (BA) a loam soil, Bordenave (BO) a sandy loam soil y Marcos Juarez a silty loam soil (MJ). The glyphosate concentration in the first 2 cm of soil was, on the average, 70% greater than in the next 2-5 cm. The mass of glyphosate in CT was higher at 2 to 10 cm depth. The depth concentration of AMPA follows the same trend than glyphosate, although its average concentration at 0-2 cm depth is 28 times higher than the glyphosate concentration at 2-5 cm (glyphosate = 147 ppb and AMPA = 4100 ppb). Beside the AMPA concentration at 0-2 cm depth is greater in NT than in CT, the mass of AMPA is higher in CT only for the Balcarce location. To our knowledge, this study is the first dealing with the depth distribution of glyphosate concentration in soils under different soil managements. In the present study, it was demonstrated that glyphosate and AMPA are present in soils under agricultural activity with maximum concentration in the first two cm of soil and the AMPA concentration at this depth is greater in NT than in CT.

  2. Interdecadal changes in snow depth on Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Webster, Melinda A.; Rigor, Ignatius G.; Nghiem, Son V.; Kurtz, Nathan T.; Farrell, Sinead L.; Perovich, Donald K.; Sturm, Matthew

    2014-08-01

    Snow plays a key role in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from cold air temperatures, slowing sea ice growth. From spring to summer, the albedo of snow determines how much insolation is absorbed by the sea ice and underlying ocean, impacting ice melt processes. Knowledge of the contemporary snow depth distribution is essential for estimating sea ice thickness and volume, and for understanding and modeling sea ice thermodynamics in the changing Arctic. This study assesses spring snow depth distribution on Arctic sea ice using airborne radar observations from Operation IceBridge for 2009-2013. Data were validated using coordinated in situ measurements taken in March 2012 during the Bromine, Ozone, and Mercury Experiment (BROMEX) field campaign. We find a correlation of 0.59 and root-mean-square error of 5.8 cm between the airborne and in situ data. Using this relationship and IceBridge snow thickness products, we compared the recent results with data from the 1937, 1954-1991 Soviet drifting ice stations. The comparison shows thinning of the snowpack, from 35.1 ± 9.4 to 22.2 ± 1.9 cm in the western Arctic, and from 32.8 ± 9.4 to 14.5 ± 1.9 cm in the Beaufort and Chukchi seas. These changes suggest a snow depth decline of 37 ± 29% in the western Arctic and 56 ± 33% in the Beaufort and Chukchi seas. Thinning is negatively correlated with the delayed onset of sea ice freezeup during autumn.

  3. Synthesis, magnetic and dielectric characterization of nanocrystalline solid solutions of In{sub 2−x}Ni{sub x}O{sub 3} (x = 0.05, 0.10 and 0.15)

    SciTech Connect

    Ahmad, Tokeer; Khatoon, Sarvari; Coolahan, Kelsey

    2013-09-01

    Graphical abstract: Monophasic and crystalline In{sub 2−x}Ni{sub x}O{sub 3} nanoparticles of size 8–15 nm have been synthesized solvothermally and showed red shift in energy band gap which decreases on increasing Ni{sup 2+} concentration in In{sub 2}O{sub 3} host lattice. - Highlights: • Monophasic Ni-doped In{sub 2}O{sub 3} nanoparticles by solvothermal method for first time. • Plausible reaction mechanism using thermogravimetric analysis. • High surface area with small particle size obtained. • Solid solutions exhibit paramagnetism with very weak antiferromagnetic interactions. - Abstract: In{sub 2−x}Ni{sub x}O{sub 3} (x = 0.05, 0.10 and 0.15) nanoparticles were successfully synthesized by solvothermal method by the thermal decomposition of oxalate precursor at 450 °C for the first time. X-ray diffraction studies showed the formation of highly crystalline and monophasic cubic structure of In{sub 2}O{sub 3} which is attributed to the formation of solid solution. These nanoparticles show good optical transmittance in the visible region. Optical measurements showed an energy band gap which decreases with increasing Ni concentration. The grain size decreases from 15 nm to 8 nm and surface area increases from 90 to 254 m{sup 2} g{sup −1} on increasing the Ni concentration. High dielectric constant and dielectric loss has been obtained which indicates the conducting nature of these solid solutions. Magnetic measurements showed that the samples are strong paramagnetic in nature with very weak antiferromagnetic interactions. No evidence of ferromagnetism is observed for these solid solutions at room temperature.

  4. Atomic-resolution scanning transmission electron microscopy study of the valence state transition in (Pr0.85Y0.15)0.7Ca0.3CoO3

    NASA Astrophysics Data System (ADS)

    Klie, Robert; Gulec, Ahmet; Phelan, Daniel; Leighton, Chris

    2015-03-01

    The observation of a first-order magnetic/electronic transition in certain Pr-based perovskite cobaltites, such as Pr0.5Ca0.5CoO3, has attracted significant attention. A simultaneous metal to insulator transition, a sharp drop in the magnetic moment and a change in the electronic structure has been reported to occur below TMIT. It was suggested that the low-temperature phase is stabilized by a shift of the mixed valence Co3+/Co4+ toward pure Co3+, enabled by a valence change of Pr3+ to Pr4+. We present an atomic-scale study of (Pr1-yYy)0.7Ca0.3CoO3 using atomic-resolution imaging, electron energy-loss spectroscopy and in-situ cooling experiments in a scanning transmission electron microscope. The valence state transition in (Pr1-yYy)0.7Ca0.3CoO3 occurs at a transition temperature TMIT ~ 135K for y = 0.15 and the in-situ cooling experiments are conducted at 90 K. At room temperature, we find oxygen vacancy ordering associated with a Co valence state ordering and we will demonstrate that the electron transfer occurs from Pr to Co below the transition temperature. The oxygen vacancy ordering disappears as a result of the Co valence state transition. The effects of oxygen mobility, sample homogeneity and the impact on the observed transition will be discussed. This work is supported by a grant from the National Science Foundation (NSF-DMR1408427).

  5. Unraveling the Degradation Process of LiNi0.8Co0.15Al0.05O2 Electrodes in Commercial Lithium Ion Batteries by Electronic Structure Investigations.

    PubMed

    Kleiner, Karin; Melke, Julia; Merz, Michael; Jakes, Peter; Nagel, Peter; Schuppler, Stefan; Liebau, Verena; Ehrenberg, Helmut

    2015-09-01

    The degradation of LiNi0.8Co0.15Al0.05O2 (LNCAO) is reflected by the electrochemical performance in the fatigued state and correlated with the redox behavior of these cathodes. The detailed electrochemical performance of these samples is investigated by galvanostatic and voltammetric cycling as well as with the galvanostatic intermittent titration technique (GITT). Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to investigate the oxidation state of all three materials at the Ni L2,3, O K, and Co L2,3 edges at five different states of charge. Surface and more bulklike properties are distinguished by total electron yield (TEY) and fluorescence yield (FY) measurements. The electrochemical investigations revealed that the changes in the cell performance of the differently aged materials can be explained by considering the reaction kinetics of the intercalation/deintercalation process. The failure of the redox process of oxygen and nickel at low voltages leads to a significant decrease of the reaction rates in the fatigued cathodes. The accompanied cyclic voltammogram (CV) peaks appear as two peaks because of the local minimum of the reaction rate, although it is one peak in the CV of the calendarically aged LNCAO. The absence of the oxidation/reduction process at low voltages can be traced back to changes in the surface morphology (formation of a NiO-like structure). Further consequences of these material changes are overpotentials, which lead to capacity losses of up to 30% (cycled with a C/3 rate). PMID:26281920

  6. Internal static electric and magnetic field at the copper cite in a single crystal of the electron-doped high-Tc superconductor Pr1.85Ce0.15CuO4 -y

    NASA Astrophysics Data System (ADS)

    Wu, Guoqing; Zamborszky, F.; Reyes, A. P.; Kuhns, P. L.; Greene, R. L.; Clark, W. G.

    2014-12-01

    We report 63 ,65Cu -NMR spectroscopy and Knight shift measurements on a single crystal of the electron-doped high-Tc superconductor Pr1.85Ce0.15CuO4 -y with an applied magnetic field (H ) up to 26.42 T. A very small NQR frequency is obtained with the observation of the spectrum, which shows an extremely wide continuous distribution of it that becomes significantly narrower below 20 K at H ∥c where the superconductivity is completely suppressed, indicating a significant change in the charge distribution at the Cu site, while the corresponding change at H ⊥c is negligible when the superconductivity is present or not fully suppressed. The Knight shift and central linewidth are proportional to the applied magnetic field with a high anisotropy. We find that the magnitude of the internal static magnetic field at the copper is dominated by the anisotropic Cu2 + 3 d orbital contributions, while its weak temperature dependence is mainly determined by the isotropic contact hyperfine coupling to the paramagnetic Pr3 + spins, which also gives rise to the full distribution of the internal static magnetic field at the copper for H ⊥c . This internal static electric and magnetic field environment at the copper is very different from that in the hole-doped cuprates, and may provide new insight into the understanding of high-Tc superconductivity. Other experimental techniques are needed to verify whether the observed significant narrowing of the charge distribution at the Cu site with H ∥c is caused by the charge ordering [E. H. da Silva Neto et al., Science (to be published, 2014)] or a new type of charge modulation.

  7. Evaluation of the effect of various mechanisms on the magnetoresistance of lanthanum manganites La0.85Sr0.15MnO3 with activation-type conductivity

    NASA Astrophysics Data System (ADS)

    Gudin, S. A.; Kurkin, M. I.; Neifel'd, E. A.; Korolev, A. V.; Gapontseva, N. N.; Ugryumova, N. A.

    2015-11-01

    A method is proposed that allows one to divide the magnetoresistance (MR) observed in manganites into three mechanisms: dimensional, orientational, and magnetic. The first two mechanisms are associated with the stratification of a substance into ferromagnetic and nonferromagnetic phases, which significantly differ in electric resistivity. The dimensional mechanism of MR is attributed to the effect of a magnetic field on the size of magnetic inclusions. The orientational mechanism of MR is determined by the dependence of electric resistivity on the mutual orientation of the magnetizations of magnetic inclusions. The magnetic mechanism of MR is determined by the properties of the magnetization of a ferromagnet, in particular, by the Curie-Weiss singularity on the temperature dependence of magnetic susceptibility at the Curie point. This mechanism exists in homogeneous substances, although its value may depend on the magnetic properties of inhomogeneities. The method is developed for substances with activation-type conductivity and is applied to the analysis of MR of La0.85Sr0.15MnO3 manganite near the Curie point, where the MR attains its maximum. The dimensional mechanism turns out to be dominant in magnetic fields H greater than the saturation field H s ( H > H s ). The orientational, dimensional, and magnetic mechanisms have a comparable effect on the MR for H < H s . The effect of the orientational mechanism on MR is relatively weak (does not exceed the third part of the total MR), although this mechanism determines the giant MR in multilayered metal films. The possibility of application of the method to the analysis of MR near the insulator-metal transition is analyzed.

  8. Evaluation of the effect of various mechanisms on the magnetoresistance of lanthanum manganites La{sub 0.85}Sr{sub 0.15}MnO{sub 3} with activation-type conductivity

    SciTech Connect

    Gudin, S. A. Kurkin, M. I.; Neifel’d, E. A.; Korolev, A. V.; Gapontseva, N. N.; Ugryumova, N. A.

    2015-11-15

    A method is proposed that allows one to divide the magnetoresistance (MR) observed in manganites into three mechanisms: dimensional, orientational, and magnetic. The first two mechanisms are associated with the stratification of a substance into ferromagnetic and nonferromagnetic phases, which significantly differ in electric resistivity. The dimensional mechanism of MR is attributed to the effect of a magnetic field on the size of magnetic inclusions. The orientational mechanism of MR is determined by the dependence of electric resistivity on the mutual orientation of the magnetizations of magnetic inclusions. The magnetic mechanism of MR is determined by the properties of the magnetization of a ferromagnet, in particular, by the Curie–Weiss singularity on the temperature dependence of magnetic susceptibility at the Curie point. This mechanism exists in homogeneous substances, although its value may depend on the magnetic properties of inhomogeneities. The method is developed for substances with activation-type conductivity and is applied to the analysis of MR of La{sub 0.85}Sr{sub 0.15}MnO{sub 3} manganite near the Curie point, where the MR attains its maximum. The dimensional mechanism turns out to be dominant in magnetic fields H greater than the saturation field H{sub s} (H > H{sub s}). The orientational, dimensional, and magnetic mechanisms have a comparable effect on the MR for H < H{sub s}. The effect of the orientational mechanism on MR is relatively weak (does not exceed the third part of the total MR), although this mechanism determines the giant MR in multilayered metal films. The possibility of application of the method to the analysis of MR near the insulator–metal transition is analyzed.

  9. High angular resolution cosmic X-ray astronomy observations in the energy range 0.15-2 keV and XUV observations of nearby stars from an attitude controlled rocket

    NASA Technical Reports Server (NTRS)

    Garmire, G. P.

    1974-01-01

    The construction of a two dimensional focusing Wolter Type I mirror system for X-ray and XUV astronomical observations from an Astrobee F sounding rocket is described. The mirror design goal will have a one degree field, a 20-arc seconds resolution, an effective area of about 50 sq cm at 1 keV and 10 sq cm at 0.25 keV on axis. A star camera provides aspect data to about 15-arc seconds. Two detectors are placed at the focus with an interchange mechanism to allow a detector change during flight. The following specific developments are reported: (1) position sensitive proportional counter development; (2) channel plate multiplier development; (3) telescope mirror development and payload structure; (4) Australian rocket flight results; (5) Comet Kohoutek He I observation; and (6) Vela, Puppis A, and Gem-Mon bright patch observations.

  10. Acoustically enriching, large-depth aquatic sampler.

    PubMed

    Jonsson, Jonas; Ogden, Sam; Johansson, Linda; Hjort, Klas; Thornell, Greger

    2012-05-01

    In marine biology, it is useful to collect water samples when exploring the distribution and diversity of microbial communities in underwater environments. In order to provide, e.g., a miniaturized submersible explorer with the capability of collecting microorganisms, a compact sample enrichment system has been developed. The sampler is 30 mm long, 15 mm wide, and just a few millimetres thick. Integrated in a multilayer steel, polyimide and glass construction is a microfluidic channel with piezoelectric transducers, where microorganism and particle samples are collected and enriched, using acoustic radiation forces for gentle and labelless trapping. High-pressure, latchable valves, using paraffin as the actuation material, at each end of the microfluidic channel keep the collected sample pristine. A funnel structure raised above the surface of the device directs water into the microfluidic channel as the vehicle propels itself or when there is a flow across its hull. The valves proved leak proof to a pressure of 2.1 MPa for 19 hours and momentary pressures of 12.5 MPa, corresponding to an ocean depth of more than 1200 metres. By reactivating the latching mechanism, small leakages through the valves could be remedied, which could thus increase the leak-less operational time. Fluorescent particles, 1.9 μm in diameter, were successfully trapped in the microfluidic channel at flow rates up to 15 μl min(-1), corresponding to an 18.5 cm s(-1) external flow rate of the sampler. In addition, liquid-suspended GFP-marked yeast cells were successfully trapped. PMID:22422039

  11. Depth map generation from geometry and motion

    NASA Astrophysics Data System (ADS)

    Li, Qianmin; Ge, Chenyang; Ren, Pengju; Yao, Huimin

    2013-07-01

    As the demand for 3DTV keep increasing these years, the conversion from exist 2D videos to 3D ones becomes a new area of research. Depth map generation plays a key point in the process. Two most important clues of depth are geometry of the scene and motion vector. This paper presents an algorithm of depth map generation, which intends to get the depth map combines two aspects of information. Compared to the previous work, our method is improved in finding vanishing point, detect motion vectors, and depth map generation.

  12. POLYSHIFT Communications Software for the Connection Machine System CM-200

    DOE PAGESBeta

    George, William; Brickner, Ralph G.; Johnsson, S. Lennart

    1994-01-01

    We describe the use and implementation of a polyshift function PSHIFT for circular shifts and end-offs shifts. Polyshift is useful in many scientific codes using regular grids, such as finite difference codes in several dimensions, and multigrid codes, molecular dynamics computations, and in lattice gauge physics computations, such as quantum chromodynamics (QCD) calculations. Our implementation of the PSHIFT function on the Connection Machine systems CM-2 and CM-200 offers a speedup of up to a factor of 3–4 compared with CSHIFT when the local data motion within a node is small. The PSHIFT routine is included in the Connection Machine Scientificmore » Software Library (CMSSL).« less

  13. Precision measurement of cosmic magnification from 21 cm emitting galaxies

    SciTech Connect

    Zhang, Pengjie; Pen, Ue-Li; /Canadian Inst. Theor. Astrophys.

    2005-04-01

    We show how precision lensing measurements can be obtained through the lensing magnification effect in high redshift 21cm emission from galaxies. Normally, cosmic magnification measurements have been seriously complicated by galaxy clustering. With precise redshifts obtained from 21cm emission line wavelength, one can correlate galaxies at different source planes, or exclude close pairs to eliminate such contaminations. We provide forecasts for future surveys, specifically the SKA and CLAR. SKA can achieve percent precision on the dark matter power spectrum and the galaxy dark matter cross correlation power spectrum, while CLAR can measure an accurate cross correlation power spectrum. The neutral hydrogen fraction was most likely significantly higher at high redshifts, which improves the number of observed galaxies significantly, such that also CLAR can measure the dark matter lensing power spectrum. SKA can also allow precise measurement of lensing bispectrum.

  14. Performance of the NASA 30 cm Ion Thruster

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Haag, Thomas W.; Hovan, Scot A.

    1993-01-01

    A 30 cm diameter xenon ion thruster is under development at NASA to provide an ion propulsion option for missions of national interest, and is being proposed for use on the USAF/TRW Space Surveillance, Tracking and Autonomous Repositioning (SSTAR) platform to validate ion propulsion. The thruster incorporates innovations in design, materials, and fabrication techniques compared to those employed in conventional ion thrusters. Specific development efforts include thruster design optimizations, component life testing and validation, vibration testing, and performance characterizations. Under this test program, the ion thruster will be brought to engineering model development status. This paper discusses the performance and power throttling test data for the NASA 30 cm diameter xenon ion thruster over an input power envelope of 0.7 to 4.9 kW, and corresponding thruster lifetime expectations.

  15. Lensing of 21-cm fluctuations by primordial gravitational waves.

    PubMed

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-25

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed. PMID:23003237

  16. Lensing of 21-cm Fluctuations by Primordial Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-01

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r˜10-9—far smaller than those currently accessible—to be probed.

  17. Viscoelastic hydrodynamic interactions and anomalous CM diffusion in polymer melts

    NASA Astrophysics Data System (ADS)

    Meyer, Hendrik; Farago, Jean; Semenov, A. N.

    2014-03-01

    We have recently discovered that anomalous center-of-mass (CM) diffusion occurring on intermediate time scales in polymer melts can be explained by the interplay of viscoelastic and hydrodynamic interactions (VHI). The theory has been solved for unentangled melts in 3D and 2D and excellent agreement between theory and simulation is found. The physical mechanism considers that hydrodynamic interactions are time dependent because of increasing viscosity before the terminal relaxation time; it is generally active in melts of any topology. Surprisingly, the effects are relevant for both, momentum-conserving and Langevin dynamics and this presentation will focus on the differences: The commonly employed Langevin thermostat significantly changes the CM motion on short and intermediate time scales, but approaching the Rouse time, the melt behavior is close to momentum-conserving simulations. On the other hand, if momentum-conserving simulations are run in too small a simulation box, the result looks as if a Langevin thermostat was used.

  18. Development of a 60 cm Magnetic Suspension System

    NASA Astrophysics Data System (ADS)

    Sawada, Hideo; Kunimasu, Tetsuya

    A 60cm Magnetic Suspension Balance System (MSBS), which has been developed in the National Aerospace Laboratory of Japan (NAL), is described in detail. Magnetic field in the MSBS is evaluated analytically and is compared with measured one. Available magnet kinds for the MSBS are selected analytically. The optimum ratio of diameter to length of cylindrical magnet for the MSBS is also evaluated. A model position sensing and the control systems are described with calibration test results. A model holding system is also shown, which is necessary for worker’s safety at suspending a large and massive model. The control system is presented and the measured model position during suspension is examined. The balance accuracy is examined and its error of drag force can be improved by restricting the calibration test to an expected drag range. Flow of the 60cm low-speed wind tunnel equipped with the MSBS is examined to be available for wind tunnel tests.

  19. 21 cm cosmology in the 21st century.

    PubMed

    Pritchard, Jonathan R; Loeb, Abraham

    2012-08-01

    Imaging the Universe during the first hundreds of millions of years remains one of the exciting challenges facing modern cosmology. Observations of the redshifted 21 cm line of atomic hydrogen offer the potential of opening a new window into this epoch. This will transform our understanding of the formation of the first stars and galaxies and of the thermal history of the Universe. A new generation of radio telescopes is being constructed for this purpose with the first results starting to trickle in. In this review, we detail the physics that governs the 21 cm signal and describe what might be learnt from upcoming observations. We also generalize our discussion to intensity mapping of other atomic and molecular lines. PMID:22828208

  20. Observing the San Andreas Fault at Depth

    NASA Astrophysics Data System (ADS)

    Ellsworth, W.; Hickman, S.; Zoback, M.; Davis, E.; Gee, L.; Huggins, R.; Krug, R.; Lippus, C.; Malin, P.; Neuhauser, D.; Paulsson, B.; Shalev, E.; Vajapeyam, B.; Weiland, C.; Zumberge, M.

    2005-12-01

    Extending 4 km into the Earth along a diagonal path that crosses the divide between Salinian basement accreted to the Pacific Plate and Cretaceous sediments of North America, the main hole at the San Andreas Fault Observatory at Depth (SAFOD) was designed to provide a portal into the inner workings of a major plate boundary fault. The successful drilling and casing of the main hole in the summer of 2005 to a total vertical depth of 3.1 km make it possible to conduct spatially extensive and long-duration observations of active tectonic processes within the actively deforming core of the San Andreas Fault. In brief, the observatory consists of retrievable seismic, deformation and environmental sensors deployed inside the casing in both the main hole (maximum temperature 135 C) and the collocated pilot hole (1.1 km depth), and a fiber optic strainmeter installed behind casing in the main hole. By using retrievable systems deployed on either wire line or rigid tubing, each hole can be used for a wide range of scientific purposes, with instrumentation that takes maximum advantage of advances in sensor technology. To meet the scientific and technical challenges of building the observatory, borehole instrumentation systems developed for use in the petroleum industry and by the academic community in other deep research boreholes have been deployed in the SAFOD pilot hole and main hole over the past year. These systems included 15Hz omni-directional and 4.5 Hz gimbaled seismometers, micro-electro-mechanical accelerometers, tiltmeters, sigma-delta digitizers, and a fiber optic interferometeric strainmeter. A 1200-m-long, 3-component 80-level clamped seismic array was also operated in the main hole for 2 weeks of recording in May of 2005, collecting continuous seismic data at 4000 sps. Some of the observational highlights include capturing one of the M 2 SAFOD target repeating earthquakes in the near-field at a distance of 420 m, with accelerations of up to 200 cm/s and a

  1. Alteration assemblages in the nakhlites: Variation with depth on Mars

    NASA Astrophysics Data System (ADS)

    Changela, H. G.; Bridges, J. C.

    2010-12-01

    Secondary mineral assemblages in the nakhlite meteorites, Lafayette, Governador Valadares (GV), Nakhla, Yamato (Y)-000593/Y-000749 have been studied using scanning electron microscopy, transmission electron microscopy, and electron probe micro analysis. The different nakhlites have distinctive secondary assemblages in their olivine grains and mesostases, showing compositional fractionation correlated with their relative depths below the Martian surface. Fracture-filled veins in Lafayette at the bottom of the pile consist of a siderite-phyllosilicate-Fe oxide-hydrated silicate gel assemblage. Corresponding veins in Nakhla and GV further up the pile are predominantly a siderite-gel assemblage, with additional evaporites including gypsum. Y-000593/Y-000749 veins are dominated by gel. The gel’s Mg/(Mg + Fe) ratio decreases from Lafayette (0.37) to GV (0.32), Nakhla (0.24), and Y-000593 (0.15). We suggest that hydrothermal fluid flowed up this depth profile, initiated by melting of buried H2O-CO2 ice. Our results show a complex mix of Fe-rich phyllosilicate within the veins and mesostasis of Lafayette with d-spacings of 0.7-1.1 nm suggesting a mixture of smectite and serpentine. The phyllosilicate formed at close to neutral pH, ≤150 °C. We also suggest that water rock ratios (W/R) of 1-10 occurred in Lafayette with smaller values for the other nakhlites. This is reflected in the volume of alteration minerals: 10% of olivine in Lafayette to 3% in Nakhla. Textural evidence of rapid cooling, together with the W/R and likely fluid velocities, suggest that the secondary assemblages formed quickly, e.g., within months. A model is proposed in which the secondary assemblages formed in an impact-induced hydrothermal system terminated by precipitation of the gel and evaporation of soluble salts.

  2. OH 18 cm Transition as a Thermometer for Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Ebisawa, Yuji; Inokuma, Hiroshi; Sakai, Nami; Menten, Karl M.; Maezawa, Hiroyuki; Yamamoto, Satoshi

    2015-12-01

    We have observed the four hyperfine components of the 18 cm OH transition toward the translucent cloud eastward of Heiles Cloud 2 (HCL2E), the cold dark cloud L134N, and the photodissociation region of the ρ-Ophiuchi molecular cloud with the Effelsberg 100 m telescope. We have found intensity anomalies among the hyperfine components in all three regions. In particular, an absorption feature of the 1612 MHz satellite line against the cosmic microwave background has been detected toward HCL2E and two positions of the ρ-Ophiuchi molecular cloud. On the basis of statistical equilibrium calculations, we find that the hyperfine anomalies originate from the non-LTE population of the hyperfine levels, and can be used to determine the kinetic temperature of the gas over a wide range of H2 densities (102-107 cm-3). Toward the center of HCL2E, the gas kinetic temperature is determined to be 53 ± 1 K, and it increases toward the cloud peripheries (˜60 K). The ortho-to-para ratio of H2 is determined to be 3.5 ± 0.9 from the averaged spectrum for the eight positions. In L134N, a similar increase of the temperature is also seen toward the periphery. In the ρ-Ophiuchi molecular cloud, the gas kinetic temperature decreases as a function of the distance from the exciting star HD 147889. These results demonstrate a new aspect of the OH 18 cm line that can be used as a good thermometer of molecular cloud envelopes. The OH 18 cm line can be used to trace a new class of warm molecular gas surrounding a molecular cloud, which is not well traced by the emission of CO and its isotopologues.

  3. Control of a 30 cm diameter mercury bombardment thruster

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Bechtel, R. T.

    1973-01-01

    Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide: (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

  4. Identifying Ionized Regions in Noisy Redshifted 21 cm Data Sets

    NASA Astrophysics Data System (ADS)

    Malloy, Matthew; Lidz, Adam

    2013-04-01

    One of the most promising approaches for studying reionization is to use the redshifted 21 cm line. Early generations of redshifted 21 cm surveys will not, however, have the sensitivity to make detailed maps of the reionization process, and will instead focus on statistical measurements. Here, we show that it may nonetheless be possible to directly identify ionized regions in upcoming data sets by applying suitable filters to the noisy data. The locations of prominent minima in the filtered data correspond well with the positions of ionized regions. In particular, we corrupt semi-numeric simulations of the redshifted 21 cm signal during reionization with thermal noise at the level expected for a 500 antenna tile version of the Murchison Widefield Array (MWA), and mimic the degrading effects of foreground cleaning. Using a matched filter technique, we find that the MWA should be able to directly identify ionized regions despite the large thermal noise. In a plausible fiducial model in which ~20% of the volume of the universe is neutral at z ~ 7, we find that a 500-tile MWA may directly identify as many as ~150 ionized regions in a 6 MHz portion of its survey volume and roughly determine the size of each of these regions. This may, in turn, allow interesting multi-wavelength follow-up observations, comparing galaxy properties inside and outside of ionized regions. We discuss how the optimal configuration of radio antenna tiles for detecting ionized regions with a matched filter technique differs from the optimal design for measuring power spectra. These considerations have potentially important implications for the design of future redshifted 21 cm surveys.

  5. Power distribution for an Am/Cm bushing melter

    SciTech Connect

    Gong, C.; Hardy, B.J.

    1996-12-31

    Decades of nuclear material production at the Savannah River Site (SRS) has resulted in the generation of large quantities of the isotopes Am{sup 243} and Cm{sup 244}. Currently, the Am and Cm isotopes are stored as a nitric acid solution in a tank. The Am and Cm isotopes have great commercial value but must be transferred to ORNL for processing. The nitric acid solution contains other isotopes and is intensely radioactive, which makes storage a problem and precludes shipment in the liquid form. In order to stabilize the material for onsite storage and to permit transport the material from SRS to ORNL, it has been proposed that the Am and Cm be separated from other isotopes in the solution and vitrified. Vitrification will be effected by depositing a liquid feed stream containing the isotopes in solution, together with a stream of glass frit, onto the top of a molten glass pool in a melter. The glass is non-conducting and the melter is a Platinum/Rhodium alloy vessel which is heated by passing an electric current through it. Because most of the power is required to evaporate the liquid feed at the top of the glass pool, power demands differ for the upper and lower parts of the melter. In addition, the melter is batch fed so that the local power requirements vary with time. In order to design a unique split power supply, which ensures adequate local power delivery, an analysis of the melter power distribution was performed with the ABAQUS finite element code. ABAQUS was used to calculate the electric potential and current density distributions in the melter for a variety of current and potential boundary conditions. The results of the calculation were compared with test data and will be used to compute power densities for input to a computational fluid dynamics model for the melter.

  6. The 21 cm signature of cosmic string wakes

    SciTech Connect

    Brandenberger, Robert H.; Danos, Rebecca J.; Hernández, Oscar F.; Holder, Gilbert P. E-mail: rjdanos@physics.mcgill.ca E-mail: holder@physics.mcgill.ca

    2010-12-01

    We discuss the signature of a cosmic string wake in 21cm redshift surveys. Since 21cm surveys probe higher redshifts than optical large-scale structure surveys, the signatures of cosmic strings are more manifest in 21cm maps than they are in optical galaxy surveys. We find that, provided the tension of the cosmic string exceeds a critical value (which depends on both the redshift when the string wake is created and the redshift of observation), a cosmic string wake will generate an emission signal with a brightness temperature which approaches a limiting value which at a redshift of z+1 = 30 is close to 400 mK in the limit of large string tension. The signal will have a specific signature in position space: the excess 21cm radiation will be confined to a wedge-shaped region whose tip corresponds to the position of the string, whose planar dimensions are set by the planar dimensions of the string wake, and whose thickness (in redshift direction) depends on the string tension. For wakes created at z{sub i}+1 = 10{sup 3}, then at a redshift of z+1 = 30 the critical value of the string tension μ is Gμ = 6 × 10{sup −7}, and it decreases linearly with redshift (for wakes created at the time of equal matter and radiation, the critical value is a factor of two lower at the same redshift). For smaller tensions, cosmic strings lead to an observable absorption signal with the same wedge geometry.

  7. Mineralogy of an unusual CM clast in the Kaidun meteorite

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Ivanov, A. V.; Yang, S. V.; Barrett, R. A.; Browning, L.

    1994-01-01

    Kaidun is breccia of disparate enstatite and carbonaceous chondrite clasts, and continues to provide real surprises. Many Daidun clasts have been intensely altered by an aqueous fluid, as evidenced by the widespread occurrence of ferromagnesian phyllosilicates and presence of carbonate- and phyllosilicate-filled veins. In this report we describe an unusual CM lithology containing beautiful aggregates of jackstraw pyrrhotites, not previously reported from any meteorite.

  8. Distinct Distribution of Purines in CM and CR Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Callahan, Michael P.; Stern, Jennifer C.; Glavin, Daniel P.; Smith, Karen E.; Martin, Mildred G.; Dworkin, Jason P.

    2010-01-01

    Carbonaceous meteorites contain a diverse suite of organic molecules and delivered pre biotic organic compounds, including purines and pyrimidines, to the early Earth (and other planetary bodies), seeding it with the ingredients likely required for the first genetic material. We have investigated the distribution of nucleobases in six different CM and CR type carbonaceous chondrites, including fivc Antarctic meteorites never before analyzed for nucleobases. We employed a traditional formic acid extraction protocol and a recently developed solid phase extraction method to isolate nucleobases. We analyzed these extracts by high performance liquid chromatography with UV absorbance detection and tandem mass spectrometry (HPLC-UV -MS/MS) targeting the five canonical RNAIDNA bases and hypoxanthine and xanthine. We detected parts-per-billion levels of nucleobases in both CM and CR meteorites. The relative abundances of the purines found in Antarctic CM and CR meteorites were clearly distinct from each other suggesting that these compounds are not terrestrial contaminants. One likely source of these purines is formation by HCN oligomerization (with other small molecules) during aqueous alteration inside the meteorite parent body. The detection of the purines adenine (A), guanine (0), hypoxanthine (HX), and xanthine (X) in carbonaceous meteorites indicates that these compounds should have been available on the early Earth prior to the origin of the first genetic material.

  9. The wedge bias in reionization 21-cm power spectrum measurements

    NASA Astrophysics Data System (ADS)

    Jensen, Hannes; Majumdar, Suman; Mellema, Garrelt; Lidz, Adam; Iliev, Ilian T.; Dixon, Keri L.

    2016-02-01

    A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way, since it is limited to a wedge-shaped region in k∥, k⊥ space. However, the power spectrum is anisotropic owing to redshift-space distortions from peculiar velocities. Consequently, the 21-cm power spectrum measured in the foreground avoidance window - which samples only a limited range of angles close to the line-of-sight direction - differs from the full redshift-space spherically averaged power spectrum which requires an average over all angles. In this paper, we calculate the magnitude of this `wedge bias' for the first time. We find that the bias amplifies the difference between the real-space and redshift-space power spectra. The bias is strongest at high redshifts, where measurements using foreground avoidance will overestimate the redshift-space power spectrum by around 100 per cent, possibly obscuring the distinctive rise and fall signature that is anticipated for the spherically averaged 21-cm power spectrum. In the later stages of reionization, the bias becomes negative, and smaller in magnitude (≲20 per cent).

  10. Percentage depth dose evaluation in heterogeneous media using thermoluminescent dosimetry.

    PubMed

    da Rosa, L A R; Cardoso, S C; Campos, L T; Alves, V G L; Batista, D V S; Facure, A

    2010-01-01

    The purpose of this study is to investigate the influence of lung heterogeneity inside a soft tissue phantom on percentage depth dose (PDD). PDD curves were obtained experimentally using LiF:Mg,Ti (TLD-100) thermoluminescent detectors and applying Eclipse treatment planning system algorithms Batho, modified Batho (M-Batho or BMod), equivalent TAR (E-TAR or EQTAR), and anisotropic analytical algorithm (AAA) for a 15 MV photon beam and field sizes of 1 x 1, 2 x 2, 5 x 5, and 10 x 10 cm 2 . Monte Carlo simulations were performed using the DOSRZnrc user code of EGSnrc. The experimental results agree with Monte Carlo simulations for all irradiation field sizes. Comparisons with Monte Carlo calculations show that the AAA algorithm provides the best simulations of PDD curves for all field sizes investigated. However, even this algorithm cannot accurately predict PDD values in the lung for field sizes of 1 x 1 and 2 x 2 cm 2 . An overdosage in the lung of about 40% and 20% is calculated by the AAA algorithm close to the interface soft tissue/lung for 1 x 1 and 2 x 2 cm 2 field sizes, respectively. It was demonstrated that differences of 100% between Monte Carlo results and the algorithms Batho, modified Batho, and equivalent TAR responses may exist inside the lung region for the 1 x 1 cm 2 field. PMID:20160687

  11. Tests of the Tully-Fisher relation. 1: Scatter in infrared magnitude versus 21 cm width

    NASA Technical Reports Server (NTRS)

    Bernstein, Gary M.; Guhathakurta, Puragra; Raychaudhury, Somak; Giovanelli, Riccardo; Haynes, Martha P.; Herter, Terry; Vogt, Nicole P.

    1994-01-01

    We examine the precision of the Tully-Fisher relation (TFR) using a sample of galaxies in the Coma region of the sky, and find that it is good to 5% or better in measuring relative distances. Total magnitudes and disk axis ratios are derived from H and I band surface photometry, and Arecibo 21 cm profiles define the rotation speeds of the galaxies. Using 25 galaxies for which the disk inclination and 21 cm width are well defined, we find an rms deviation of 0.10 mag from a linear TFR with dI/d(log W(sub c)) = -5.6. Each galaxy is assumed to be at a distance proportional to its redshift, and an extinction correction of 1.4(1-b/a) mag is applied to the total I magnitude. The measured scatter is less than 0.15 mag using milder extinction laws from the literature. The I band TFR scatter is consistent with measurement error, and the 95% CL limits on the intrinsic scatter are 0-0.10 mag. The rms scatter using H band magnitudes is 0.20 mag (N = 17). The low width galaxies have scatter in H significantly in excess of known measurement error, but the higher width half of the galaxies have scatter consistent with measurement error. The H band TFR slope may be as steep as the I band slope. As the first applications of this tight correlation, we note the following: (1) the data for the particular spirals commonly used to define the TFR distance to the Coma cluster are inconsistent with being at a common distance and are in fact in free Hubble expansion, with an upper limit of 300 km/s on the rms peculiar line-of-sight velocity of these gas-rich spirals; and (2) the gravitational potential in the disks of these galaxies has typical ellipticity less than 5%. The published data for three nearby spiral galaxies with Cepheid distance determinations are inconsistent with our Coma TFR, suggesting that these local calibrators are either ill-measured or peculiar relative to the Coma Supercluster spirals, or that the TFR has a varying form in different locales.

  12. True amplitude prestack depth migration

    NASA Astrophysics Data System (ADS)

    Deng, Feng

    Reliable analysis of amplitude variation with offset (or with angle) requires accurate amplitudes from prestack migration. In routine seismic data processing, amplitude balancing and automatic gain control are often used to reduce amplitude lateral variations. However, these methods are empirical and lack a solid physical basis; thus, there are uncertainties that might produce erroneous conclusions, and hence cause economic loss. During wavefield propagation, geometrical spreading, intrinsic attenuation, transmission losses and the energy conversion significantly distort the wavefield amplitude. Most current true-amplitude migrations usually compensate only for geometrical spreading. A new prestack depth migration based on the framework of reverse-time migration in the time-space domain was developed in this dissertation with the aim of compensating all of the propagation effects in one integrated algorithm. Geometrical spreading is automatically included because of the use of full two-way wave extrapolation. Viscoelastic wave equations are solved to handle the intrinsic attenuation with a priori quality factor. Transmission losses for both up- and down-going waves are compensated using a two-pass, recursive procedure based on extracting the angle-dependent reflection/transmission coefficients from prestack migration. The losses caused by the conversion of energy from one elastic model to another are accounted for through elastic wave extrapolation; the influence of the S wave velocity contrast on the P wave reflection coefficient is implicitly included by using the Zoeppritz equations to describe the reflection and transmission at an elastic interface. Only smooth background models are assumed to be known. The contrasts/ratios of the model parameters can be estimated by fitting the compensated angle-dependent reflection coefficients obtained from data for multiple sources. This is one useful by-product of the algorithm. Numerical tests on both 2D and 3D scalar

  13. The effect of the thread depth on the mechanical properties of the dental implant

    PubMed Central

    2015-01-01

    PURPOSE This study aimed to evaluate the effect of implant thread depth on primary stability in low density bone. MATERIALS AND METHODS The insertion torque was measured by inserting Ti implants with different thread depths into solid rigid polyurethane blocks (Sawbones) with three different bone densities (0.16 g/cm3, 0.24 g/cm3, and 0.32 g/cm3). The insertion torque value was evaluated with a surgical engine. The static compressive strength was measured with a universal testing machine (UTM) and the Ti implants were aligned at 30° against the loading direction of the UTM. After the static compressive strength test, the Ti implants were analyzed with a Measurescope. RESULTS The Ti implants with deeper thread depth showed statistically higher mean insertion torque values (P<.001). Groups A and group B had similar maximum static compressive strengths, as did groups C and D (P>.05). After the static compressive strength, the thread shape of the Ti implants with deeper thread depth did not show any breakage but did show deformation of the implant body and abutment. CONCLUSION The implants with deeper thread depth had higher mean insertion torque values but not lower compressive strength. The deep threads had a mechanical stability. Implants with deeper thread depth may increase the primary stability in areas of poor quality bone without decreasing mechanical strength. PMID:25932309

  14. Estimation of foot pressure from human footprint depths using 3D scanner

    NASA Astrophysics Data System (ADS)

    Wibowo, Dwi Basuki; Haryadi, Gunawan Dwi; Priambodo, Agus

    2016-03-01

    The analysis of normal and pathological variation in human foot morphology is central to several biomedical disciplines, including orthopedics, orthotic design, sports sciences, and physical anthropology, and it is also important for efficient footwear design. A classic and frequently used approach to study foot morphology is analysis of the footprint shape and footprint depth. Footprints are relatively easy to produce and to measure, and they can be preserved naturally in different soils. In this study, we need to correlate footprint depth with corresponding foot pressure of individual using 3D scanner. Several approaches are used for modeling and estimating footprint depths and foot pressures. The deepest footprint point is calculated from z max coordinate-z min coordinate and the average of foot pressure is calculated from GRF divided to foot area contact and identical with the average of footprint depth. Evaluation of footprint depth was found from importing 3D scanner file (dxf) in AutoCAD, the z-coordinates than sorted from the highest to the lowest value using Microsoft Excel to make footprinting depth in difference color. This research is only qualitatif study because doesn't use foot pressure device as comparator, and resulting the maximum pressure on calceneus is 3.02 N/cm2, lateral arch is 3.66 N/cm2, and metatarsal and hallux is 3.68 N/cm2.

  15. Depth of artificial Burrowing Owl burrows affects thermal suitability and occupancy

    USGS Publications Warehouse

    Nadeau, Christopher P.; Conway, Courtney J.; Rathbun, Nathan

    2015-01-01

    Many organizations have installed artificial burrows to help bolster local Burrowing Owl (Athene cunicularia) populations. However, occupancy probability and reproductive success in artificial burrows varies within and among burrow installations. We evaluated the possibility that depth below ground might explain differences in occupancy probability and reproductive success by affecting the temperature of artificial burrows. We measured burrow temperatures from March to July 2010 in 27 artificial burrows in southern California that were buried 15–76 cm below the surface (measured between the surface and the top of the burrow chamber). Burrow depth was one of several characteristics that affected burrow temperature. Burrow temperature decreased by 0.03°C per cm of soil on top of the burrow. The percentage of time that artificial burrows provided a thermal refuge from above-ground temperature decreased with burrow depth and ranged between 50% and 58% among burrows. The percentage of time that burrow temperature was optimal for incubating females also decreased with burrow depth and ranged between 27% and 100% among burrows. However, the percentage of time that burrow temperature was optimal for unattended eggs increased with burrow depth and ranged between 11% and 95% among burrows. We found no effect of burrow depth on reproductive success across 21 nesting attempts. However, occupancy probability had a non-linear relationship with burrow depth. The shallowest burrows (15 cm) had a moderate probability of being occupied (0.46), burrows between 28 and 40 cm had the highest probability of being occupied (>0.80), and burrows >53 cm had the lowest probability of being occupied (<0.43). Burrowing Owls may prefer burrows at moderate depths because these burrows provide a thermal refuge from above-ground temperatures, and are often cool enough to allow females to leave eggs unattended before the onset of full-time incubation, but not too cool for incubating females that

  16. How to synthesize pure Li2-xFeSi1-xPxO4/C (x = 0.03-0.15) easily from low-cost Fe(3+) as cathode materials for Li-ion batteries.

    PubMed

    Chen, Weihua; Zhu, Dan; Li, Yanyang; Li, Chaopeng; Feng, Xiangming; Guan, Xinxin; Yang, Changchun; Zhang, Jianmin; Mi, Liwei

    2015-09-01

    Li2FeSiO4 is a low-cost, environmentally friendly electrode material with high theoretical capacity. However, obtaining pure-phase Li2FeSiO4 on a large scale is difficult. In this study, pure Li2-xFeSi1-xPxO4/C is prepared easily by using the low cost compound Fe(NO3)3·9H2O, with the help of citric acid and appropriate ratios of NH4H2PO4 (x = 0.03-0.15). The possible mechanism of the system with NH4H2PO4 to synthesize Li2-xFeSi1-xPxO4/C is that there is a catalysis process in the system, which helps to produce H2, providing a reducing environment in every particle of the reactants guaranteeing a complete change from Fe(3+) to Fe(2+). The produced H2 is verified by the gas chromatography of the collected gas produced in the calcination process. The ratios of NH4H2PO4 in this system could adjust the valence of element Fe in the products. Without NH4H2PO4, an Fe2O3 impurity is formed accompanying the Li2FeSiO4. With the addition of 1 at% NH4H2PO4, the Li4SiO4 impurity accords with the objective Li2-xFeSi1-xPxO4/C. Also, Fe with zero-valence could be found as an impurity with the addition of 20 at% NH4H2PO4 due to overreduction in the system. The synthesized pure Li2-xFeSi1-xPxO4/C (x = 0.03) displayed the highest discharge capacity of 179 mA h g(-1) in the first cycle, the best discharge capacity retention and the most reliable redox reversibility of the coulombic efficiency (approximately 100%), compared with the synthesized materials with Fe2O3 or Li4SiO4 impurities. PMID:26221759

  17. Atomic-resolution studies of epitaxial strain release mechanisms in L a1.85S r0.15Cu O4 /L a0.67C a0.33Mn O3 superlattices

    NASA Astrophysics Data System (ADS)

    Biškup, N.; Das, S.; Gonzalez-Calbet, J. M.; Bernhard, C.; Varela, M.

    2015-05-01

    In this paper we present an atomic-resolution electron microscopy study of superlattices (SLs) where the colossal magnetoresistant manganite L a0.67C a0.33Mn O3 (LCMO) and the high critical temperature superconducting cuprate L a1.85S r0.15Cu O4 (LSCO) are combined. Although good quality epitaxial growth can be achieved, both the choice of substrate and the relatively large lattice mismatch between these materials (around 2%) have a significant impact on the system properties [Phys. C 468, 991 (2008), 10.1016/j.physc.2008.05.001; Nature (London) 394, 453 (1998), 10.1038/28810]. Our samples, grown by pulsed laser deposition, are epitaxial and exhibit high structural quality. By means of cutting-edge electron microscopy and spectroscopy techniques we still find that the epitaxial strain is accommodated by a combination of defects, such as interface steps and antiphase boundaries in the manganite. These defects result in inhomogeneous strain fields through the samples. Also, some chemical inhomogeneities are detected, up to the point that novel phases nucleate. For example, at the LCMO/LSCO interface the AB O3 -type manganite adopts a tetragonal LSCO-like structure forming localized layers that locally resemble the composition of L a2 /3C a4 /3Mn O4 . Structural distortions are detected in the cuprate as well, which may extend over lateral distances of several unit cells. Finally, we also analyze the influence of the substrate-induced strain by examining superlattices grown on two different substrates: (LaAlO3) 0.3(Sr2AlTaO6 ) 0.7 (LSAT) and LaSrAl O4 (LSAO). We observe that SLs grown on LSAT, which are nonsuperconducting, present reduced values of the c axis compared to superlattices grown on LSAO (which are fully superconducting). This finding points to the fact that the proper distance between copper planes in LSCO is essential in obtaining superconductivity in cuprates.

  18. Root carbon decomposition and microbial biomass response at different soil depths

    NASA Astrophysics Data System (ADS)

    Rumpel, C.

    2012-12-01

    The relationship between root litter addition and soil organic matter (SOM) formation in top- versus subsoils is unknown. The aim of this study was to investigate root litter decomposition and stabilisation in relation to microbial parameters in different soil depths. Our conceptual approach included incubation of 13C-labelled wheat roots at 30, 60 and 90 cm soil depth for 36 months under field conditions. Quantitative root carbon contribution to SOM was assessed, changes of bulk root chemistry studied by solid-state 13C NMR spectroscopy and lignin content and composition was assessed after CuO oxidation. Compound-specific isotope analysis allowed to assess the role of root lignin for soil C storage in the different soil depths. Microbial biomass and community structure was determined after DNA extraction. After three years of incubation, O-alkyl C most likely assigned to polysaccharides decreased in all soil depth compared to the initial root material. The degree of root litter decomposition assessed by the alkyl/O-alkyl ratio decreased with increasing soil depth, while aryl/O-alkyl ratio was highest at 60 cm depth. Root-derived lignin showed depth specific concentrations (30 < 90 < 60 cm). Its composition was soil depth independent suggesting that microbial communities in all three soil depths had similar degradation abilities. Microbial biomass C and fungi contribution increased after root litter addition. Their community structure changed after root litter addition and showed horizon specific dynamics. Our study shows that root litter addition can contribute to C storage in subsoils but did not influence C storage in topsoil. We conclude that specific conditions of single soil horizons have to be taken into account if root C dynamics are to be fully understood.

  19. Imaging and timing performance of 1 cm x 1 cm position-sensitive solid-state photomultiplier

    NASA Astrophysics Data System (ADS)

    Dokhale, P.; Schmall, J.; Stapels, C.; Christian, J.; Cherry, S. R.; Squillante, M. R.; Shah, K.

    2013-02-01

    We have designed and built a large-area 1cm × 1cm position-sensitive solid-state photomultiplier (PS-SSPM) for use in detector design for medical imaging applications. Our new large-area PS-SSPM concept implements resistive network between the micro-pixels, which are photodiodes operated in Geiger mode, called Geiger Photodiodes (GPDs), to provide continuous position sensitivity. Here we present imaging and timing performance of the large-area PS-SSPM for different temperatures and operating biases to find the optimum operating parameters for the device in imaging applications. A detector module was built by coupling a polished 8 × 8 LYSO array, with 1 × 1 × 20 mm3 elements, to a 1 × 1 cm2 PS-SSPM. Flood images recorded at room temperature show good crystal separation as all 64 elements were separated from each other. Cooling the device at 10 °C showed significant improvement. The device optimum bias voltage was ~ 4.5V over breakdown voltage. The coincidence timing resolution was improved significantly by increasing the operating bias, as well as by lowering the temperature to 0 °C. Results show excellent imaging performance and good timing response with a large-area PS-SSPM device.

  20. The amino acid and hydrocarbon contents of the Paris meteorite, the most primitive CM chondrite

    NASA Astrophysics Data System (ADS)

    Martins, Zita; Modica, Paola; Zanda, Brigitte; Le Sergeant d'Hendecourt, Louis

    2015-04-01

    The Paris meteorite is reported to be the least aqueously altered CM chondrite [1,2], and to have experienced only weak thermal metamorphism [2-5]. The IR spectra of some of Paris' fragments suggest a primitive origin for the organic matter in this meteorite, similar to the spectra from solid-state materials in molecular clouds [6]. Most of the micron-sized organic particles present in the Paris matrix exhibit 0 < δD <2000‰ [7,8]. In order to understand the effect of aqueous alteration and thermal metamorphism on the abundance and distribution of meteoritic soluble organic matter, we have analyzed for the first time the amino acid and hydrocarbon contents of the Paris meteorite [9]. Extensive aqueous alteration in the parent body of carbonaceous meteorites may result in the decomposition of α-amino acids and the synthesis of β- and γ-amino acids. When plotted with several CM chondrites, Paris has the lowest relative abundance of β-alanine/glycine (0.15) for a CM chondrite, which fits with the relative abundance of β-alanine/glycine increasing with increasing aqueous alteration [10,11]. In addition, our results show that the isovaline detected in this meteorite is racemic (D/L= 0.99 ± 0.08; L-enantiomer excess (%) = 0.35 ± 0.5; corrected D/L = 1.03; corrected L-enantiomer excess (%) = -1.4 ± 2.6). Although aqueous alteration does not create by itself an isovaline asymmetry, it may amplify a small enantiomeric excess. Therefore, our data may support the hypothesis that aqueous alteration is responsible for the high L-enantiomer excess of isovaline observed in the most aqueously altered carbonaceous meteorites [12,13]. Paris has n-alkanes ranging from C16 to C25 and 3- to 5-ring non-alkylated polycyclic aromatic hydrocarbons (PAHs). The lack of alkylated PAHs in Paris seems to be related to the low degree of aqueous alteration on its parent body [9,14]. The extra-terrestrial aliphatic and aromatic hydrocarbon content of Paris may have an interstellar origin

  1. Multiple precursors of secondary mineralogical assemblages in CM chondrites

    NASA Astrophysics Data System (ADS)

    Pignatelli, Isabella; Marrocchi, Yves; Vacher, Lionel. G.; Delon, RéMi; Gounelle, Matthieu

    2016-04-01

    We report a petrographic and mineralogical survey of tochilinite/cronstedtite intergrowths (TCIs) in Paris, a new CM chondrite considered to be the least altered CM identified to date. Our results indicate that type-I TCIs consist of compact tochilinite/cronstedtite rims surrounding Fe-Ni metal beads, thus confirming kamacite as the precursor of type-I TCIs. In contrast, type-II TCIs are characterized by complex compositional zoning composed of three different Fe-bearing secondary minerals: from the outside inwards, tochilinite, cronstedtite, and amakinite. Type-II TCIs present well-developed faces that allow a detailed morphological analysis to be performed in order to identify the precursors. The results demonstrate that type-II TCIs formed by pseudomorphism of the anhydrous silicates, olivine, and pyroxene. Hence, there is no apparent genetic relationship between type-I and type-II TCIs. In addition, the complex chemical zoning observed within type-II TCIs suggests that the alteration conditions evolved dramatically over time. At least three stages of alteration can be proposed, characterized by alteration fluids with varying compositions (1) Fe- and S-rich fluids; (2) S-poor and Fe- and Si-rich fluids; and (3) S- and Si-poor, Fe-rich fluids. The presence of unaltered silicates in close association with euhedral type-II TCIs suggests the existence of microenvironments during the first alteration stages of CM chondrites. In addition, the absence of Mg-bearing secondary minerals in Paris TCIs suggests that the Mg content increases during the course of alteration.

  2. The foreground wedge and 21-cm BAO surveys

    NASA Astrophysics Data System (ADS)

    Seo, Hee-Jong; Hirata, Christopher M.

    2016-03-01

    Redshifted H I 21 cm emission from unresolved low-redshift large-scale structure is a promising window for ground-based baryon acoustic oscillations (BAO) observations. A major challenge for this method is separating the cosmic signal from the foregrounds of Galactic and extra-Galactic origins that are stronger by many orders of magnitude than the former. The smooth frequency spectrum expected for the foregrounds would nominally contaminate only very small k∥ modes; however, the chromatic response of the telescope antenna pattern at this wavelength to the foreground introduces non-smooth structure, pervasively contaminating the cosmic signal over the physical scales of our interest. Such contamination defines a wedged volume in Fourier space around the transverse modes that is inaccessible for the cosmic signal. In this paper, we test the effect of this contaminated wedge on the future 21-cm BAO surveys using Fisher information matrix calculation. We include the signal improvement due to the BAO reconstruction technique that has been used for galaxy surveys and test the effect of this wedge on the BAO reconstruction as a function of signal to noises and incorporate the results in the Fisher matrix calculation. We find that the wedge effect expected at z = 1-2 is very detrimental to the angular diameter distances: the errors on angular diameter distances increased by 3-4.4 times, while the errors on H(z) increased by a factor of 1.5-1.6. We conclude that calibration techniques that clean out the foreground `wedge' would be extremely valuable for constraining angular diameter distances from intensity-mapping 21-cm surveys.

  3. Embolisation of Small (< 3 cm) Brain Arteriovenous Malformations

    PubMed Central

    Willinsky, R.; Goyal, M.; terBrugge, K.; Montanera, W.; Wallace*, M.G; Tymianski*, M.

    2001-01-01

    Summary The role of embolisation in the treatment of small (< 3cm) brain arteriovenous malformations (AVMs) has not been elucidated. We reviewed our experience using embolisation in the treatment of small AVMs and correlated a proposed grading system based on the angioarchitecture to the percentage obliteration achieved by embolisation. Eighty-one small AVMs in 80 patients were embolised from 1984 to 1999. The age range was from 3 to 72 years. The AVMs were given a score from 0 to 6 based on the angioarchitecture. The assigned scores were as follows: nidus (fistula = 0, < 1 cm = 1,1-3 cm = 2), type of feeding arteries (cortical = 0, perforator or choroidal = 1), number of feeding arteries (single = 0, multiple -2) and number of draining veins (single = 0\\ multiple - 1). Angiographic results based on percentage obliteration were grouped into three categories: complete, 66-99%, and 0-65%. The goal of embolisation was cure in 27 AVMs, pre-surgical in 23, pre-radiosurgery in 26, and elimination of an aneurysm in five. Embolisation achieved complete obliteration in 22 (27%) of the 81 AVMs. In the AVMs where the goal was cure, 19 (70%) of 27 were completely obliterated. In the AVMs with angioarchitecture scores of 0-2, 12 (86%) of 14 were cured, with scores of 3-4, 8 (34%) of 24 were cured and with scores of 5-6, 2 (4%) of 44 were cured. Embolisation resulted in transient morbidity of 5.0%, permanent morbidity of 2.5%, and mortality of 1.2%. There were no complications in AVMs with scores of 0-2. Embolisation is an effective treatment of small AVMs when the angioarchitecture is favourable (scores 0-2). This includes pure fistulas and AVMs with a single, pial, feeding artery. PMID:20663327

  4. Ureteroscopic treatment of larger renal calculi (>2 cm)

    PubMed Central

    Bagley, Demetrius H.; Healy, Kelly A.; Kleinmann, Nir

    2012-01-01

    Objectives To evaluate the current status of ureteroscopic lithotripsy (UL) for treating renal calculi of >2 cm, as advances in flexible ureteroscope design, accessory instrumentation and lithotrites have revolutionised the treatment of urinary calculi. While previously reserved for ureteric and small renal calculi, UL has gained an increasing role in the selective management of larger renal stone burdens. Methods We searched the available databases, including PubMed, Google Scholar, and Scopus, for relevant reports in English, and the article bibliographies to identify additional relevant articles. Keywords included ureteroscopy, lithotripsy, renal calculi, and calculi >2 cm. Retrieved articles were reviewed to consider the number of patients, mean stone size, success rates, indications and complications. Results In all, nine studies (417 patients) were eligible for inclusion. After one, two or three procedures the mean (range) success rates were 68.2 (23–84)%, 87.1 (79–91)% and 94.4 (90.1–96.7)%, respectively. Overall, the success rate was >90% with a mean of 1.2–2.3 procedures per patient. The overall complication rate was 10.3%, including six (1.4%) intraoperative and 37 (8.9%) postoperative complications, most of which were minor. The most common indications for UL were a failed previous treatment (46%), comorbidities (18.2%), and technical and anatomical factors (12.3%). Conclusions UL is safe and effective for treating large renal calculi. While several procedures might be required for total stone clearance, UL should be considered a standard approach in the urologist’s options treating renal calculi of >2 cm. PMID:26558040

  5. Recycle Requirements for NASA's 30 cm Xenon Ion Thruster

    NASA Technical Reports Server (NTRS)

    Pinero, Luis R.; Rawlin, Vincent K.

    1994-01-01

    Electrical breakdowns have been observed during ion thruster operation. These breakdowns, or arcs, can be caused by several conditions. In flight systems, the power processing unit must be designed to handle these faults autonomously. This has a strong impact on power processor requirements and must be understood fully for the power processing unit being designed for the NASA Solar Electric Propulsion Technology Application Readiness program. In this study, fault conditions were investigated using a NASA 30 cm ion thruster and a power console. Power processing unit output specifications were defined based on the breakdown phenomena identified and characterized.

  6. Performance mapping of a 30 cm engineering model thruster

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; Vahrenkamp, R. P.

    1975-01-01

    A 30 cm thruster representative of the engineering model design has been tested over a wide range of operating parameters to document performance characteristics such as electrical and propellant efficiencies, double ion and beam divergence thrust loss, component equilibrium temperatures, operational stability, etc. Data obtained show that optimum power throttling, in terms of maximum thruster efficiency, is not highly sensitive to parameter selection. Consequently, considerations of stability, discharge chamber erosion, thrust losses, etc. can be made the determining factors for parameter selection in power throttling operations. Options in parameter selection based on these considerations are discussed.

  7. Affordable échelle spectroscopy with a 60 cm telescope

    NASA Astrophysics Data System (ADS)

    Pribulla, T.; Garai, Z.; Hambálek, L.; Kollár, V.; Komžík, R.; Kundra, E.; Nedoroščík, J.; Sekeráš, M.; Vaňko, M

    2015-09-01

    A new fiber-fed spectrograph was installed at the 60 cm telescope of the Stará Lesná Observatory. The article presents tests of its performance (spectral resolution, signal-to-noise ratio, radial-velocity stability) and reports observations of selected variable stars and exoplanet host stars. First test observations show that the spectrograph is an ideal tool to observe bright eclipsing and spectroscopic binaries but also symbiotic and nova-like stars. The radial-velocity stability (60-80 ms-1) is sufficient to study spectroscopic binaries and to detect easily the orbital motion of hot-Jupiter extrasolar planets around bright stars.

  8. Performance of 30-cm ion thrusters with dished accelerator grids

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Thirteen sets of dished accelerator grids were treated on five different 30 cm diameter bombardment thrusters to evaluate the effects of grid geometry variations on thruster discharge chamber performance. The dished grid parameters varied were: grid-to-grid spacing, screen and accelerator grid hole diameter, screen and accelerator open area fraction, compensation for beam divergence losses, and accelerator grid thickness. The effects on discharge chamber performance of main magnetic field changes, magnetic baffle current, cathode pole piece length and cathode position were also investigated.

  9. Performance documentation of the engineering model 30-cm diameter thruster

    NASA Technical Reports Server (NTRS)

    Bechtel, R. T.; Rawlin, V. K.

    1976-01-01

    The results of extensive testing of two 30-cm ion thrusters which are virtually identical to the 900 series Engineering Model Thruster in an ongoing 15,000-hour life test are presented. Performance data for the nominal fullpower (2650 W) operating point; performance sensitivities to discharge voltage, discharge losses, accelerator voltage, and magnetic baffle current; and several power throttling techniques (maximum Isp, maximum thrust/power ratio, and two cases in between are included). Criteria for throttling are specified in terms of the screen power supply envelope, thruster operating limits, and control stability. In addition, reduced requirements for successful high voltage recycles are presented.

  10. The 100 cm solar telescope primary mirror study

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The manufacturing impact of primary mirror configuration on the performance of a 100 cm aperture solar telescope was studied. Three primary mirror configurations were considered: solid, standard lightweight, and mushroom. All of these are of low expansion material. Specifically, the study consisted of evaluating the mirrors with regard to: manufacturing metrology, manufacturing risk factors and ultimate quality assessment. As a result of this evaluation, a performance comparison of the configurations was made, and a recommendation of mirror configuration is the final output. These evaluations, comparisons and recommendations are discussed in detail. Other investigations were completed and are documented in the appendices.

  11. Control of a 30 cm diameter mercury bombardment thruster

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Bechtel, R. T.

    1973-01-01

    Increased thruster performance has made closed-loop automatic control more difficult than previously. Specifically, high perveance optics tend to make reliable recycling more difficult. Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

  12. Radiated and conducted EMI from a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Whittlesey, A. C.; Peer, W.

    1981-01-01

    In order to properly assess the interaction of a spacecraft with the EMI environment produced by an ion thruster, the EMI environment was characterized. Therefore, radiated and conducted emissions were measured from a 30-cm mercury ion thruster. The ion thruster beam current varied from zero to 2.0 amperes and the emissions were measured from 5 KHz to 200 MHz. Several different types of antennas were used to obtain the measurements. The various measurements that were made included: magnetic field due to neutralizer/beam current loop; radiated electric fields of thruster and plume; and conducted emissions on arc discharge, neutralizer keeper and magnetic baffle lines.

  13. Endurance testing of a 30-cm Kaufman thruster

    NASA Technical Reports Server (NTRS)

    Collett, C. R.

    1973-01-01

    Results of a program to demonstrate lifetime capability of a 30-cm Kaufman ion thruster with a 6000 hour endurance test are described. Included in the program are (1) thruster fabrication, (2) design and construction of a test console containing a transistorized high frequency power processor, and control circuits which provide unattended automatic operation of the thruster, and (3) modification of a vacuum facility to incorporate a frozen mercury collector and permit unattended operation. Four tests ranging in duration from 100 to 1100 hours have been completed. These tests and the resulting thruster modifications are described. The status of the endurance test is also presented.

  14. Long lifetime hollow cathodes for 30-cm mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Kerslake, W. R.

    1976-01-01

    An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

  15. A multiple thruster array for 30-cm thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Mantenieks, M. A.

    1975-01-01

    The 3.0-m diameter chamber of the 7.6-m diameter by 21.4-m long vacuum tank at NASA LeRC was modified to permit testing of an array of up to six 30-cm thrusters with a variety of laboratory and thermal vacuum bread-board power systems. A primary objective of the Multiple Thruster Array (MTA) program is to assess the impact of multiple thruster operation on individual thruster and power processor requirements. The areas of thruster startup, steady-state operation, throttling, high voltage recycle, thrust vectoring, and shutdown are of special concern. The results of initial tests are reported.

  16. Performance capabilities of the 8-cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1981-01-01

    A preliminary characterization of the performance capabilities of the 8-cm thruster in order to initiate an evaluation of its application to LSS propulsion requirements is presented. With minor thruster modifications, the thrust was increased by about a factor of four while the discharge voltage was reduced from 39 to 22 volts. The thruster was operated over a range of specific impulse of 1950 to 3040 seconds and a maximum total efficiency of about 54 percent was attained. Preliminary analysis of component lifetimes, as determined by temperature and spectroscopic line intensity measurements, indicated acceptable thruster lifetimes are anticipated at the high power level operation.

  17. Status of 30 cm mercury ion thruster development

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.; King, H. J.

    1974-01-01

    Two engineering model 30-cm ion thrusters were assembled, calibrated, and qualification tested. This paper discusses the thruster design, performance, and power system. Test results include documentation of thrust losses due to doubly charged mercury ions and beam divergence by both direct thrust measurements and beam probes. Diagnostic vibration tests have led to improved designs of the thruster backplate structure, feed system, and harness. Thruster durability is being demonstrated over a thrust range of 97 to 113 mN at a specific impulse of about 2900 seconds. As of August 15, 1974, the thruster has successfully operated for over 4000 hours.

  18. The 8-CM ion thruster characterization. [mercury ion engine

    NASA Technical Reports Server (NTRS)

    Wessel, F. J.; Williamson, W. S.

    1983-01-01

    The performance capabilities of the 8 cm diameter mercury ion thruster were increased by modifying the thruster operating parameters and component hardware. The initial performance levels, representative of the Hughes/NASA Lewis Research Center Ion Auxiliary Propulsion Subsystem (IAPS) thruster, were raised from the baseline values of thrust, T = 5 mN, and specific impulse, I sub sp = 2,900s, to thrust, T = 25 mN and specific impulse, I sub sp = 4,300 s. Performance characteristics including estmates of the erosion rates of various component surfaces are presented.

  19. Human Being Imaging with cm-Wave UWB Radar

    NASA Astrophysics Data System (ADS)

    Yarovoy, A.; Zhuge, X.; Savelyev, T.; Matuzas, J.; Levitas, B.

    Possibilities of high-resolution human body imaging and concealed weapon detection using centimeter-wave microwave frequencies are investigated. Dependencies of the cross-range resolution of different imaging techniques on operational bandwidth, center frequency, imaging aperture size, and imaging topology have been studied. It has been demonstrated that the cross-range resolution of 2 cm can be achieved using frequencies below 10 GHz. These findings have been verified experimentally by producing high-resolution images of a foil-covered doll and some weapons.

  20. Development of an 8-cm engineering model thruster system

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hyman, J., Jr.; Hopper, D. J.

    1976-01-01

    Electric propulsion has been shown to offer major advantages over the techniques currently employed for the control of earth satellites. For a user to realize these advantages, however, requires the availability of a proven, operationally flight-ready propulsion system. Currently an Engineering Model of an 8-cm ion thruster propulsion system is under development. The system includes the thruster unit with its associated reservoir, thruster gimbaling subsystem, and power processing unit. This paper describes the EM System with special emphasis on hardware design and system performance.

  1. Performance of 30-cm ion thrusters with dished accelerator grids

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Thirteen sets of dished accelerator grids were tested on five different 30-cm diameter bombardment thrustors to evaluate the effects of grid geometry variations on thrustor discharge chamber performance. The dished grid parameters varied were: grid-to-grid spacing, screen and accelerator grid hole-diameter, screen and accelerator open area fraction, compensation for beam divergence losses, and accelerator grid thickness. Also investigated were the effects on discharge chamber performance of main magnetic field changes, magnetic baffle current cathode pole piece length and cathode position.

  2. X-ray depth-dose characteristics of the Toshiba LMR-16.

    PubMed

    Mantel, J; Perry, H; Weinkam, J J

    1979-01-01

    The depth-dose characteristics of the Toshiba LMR-16 linear accelerator for 14-MeV x rays have been measured at an SSD of 100 cm using diodes and ion chambers. The surface dose and build-up depth both exhibit a considerable variation with field size. A new central axis model has been developed which takes account of these variations, and the agreement between the measured and computed data using this model is found to be excellent. Formulas are also presented to estimate the surface dose, buildup depth, and output factor as a function of field size. PMID:460069

  3. Redshift-space distortion of the 21-cm background from the epoch of reionization - I. Methodology re-examined

    NASA Astrophysics Data System (ADS)

    Mao, Yi; Shapiro, Paul R.; Mellema, Garrelt; Iliev, Ilian T.; Koda, Jun; Ahn, Kyungjin

    2012-05-01

    The peculiar velocity of the intergalactic gas responsible for the cosmic 21-cm background from the epoch of reionization and beyond introduces an anisotropy in the three-dimensional power spectrum of brightness temperature fluctuations. Measurement of this anisotropy by future 21-cm surveys is a promising tool for separating cosmology from 21-cm astrophysics. However, previous attempts to model the signal have often neglected peculiar velocity or only approximated it crudely. This paper re-examines the effects of peculiar velocity on the 21-cm signal in detail, improving upon past treatment and addressing several issues for the first time. (1) We show that even the angle-averaged power spectrum, P(k), is affected significantly by the peculiar velocity. (2) We re-derive the brightness temperature dependence on atomic hydrogen density, spin temperature, peculiar velocity and its gradient and redshift to clarify the roles of thermal versus velocity broadening and finite optical depth. (3) We show that properly accounting for finite optical depth eliminates the unphysical divergence of the 21-cm brightness temperature in overdense regions of the intergalactic medium found by previous work that employed the usual optically thin approximation. (4) We find that the approximation made previously to circumvent the diverging brightness temperature problem by capping the velocity gradient can misestimate the power spectrum on all scales. (5) We further show that the observed power spectrum in redshift space remains finite even in the optically thin approximation if one properly accounts for the redshift-space distortion. However, results that take full account of finite optical depth show that this approximation is only accurate in the limit of high spin temperature. (6) We also show that the linear theory for redshift-space distortion widely employed to predict the 21-cm power spectrum results in a ˜30 per cent error in the observationally relevant wavenumber range k˜ 0

  4. Image inpainting strategy for Kinect depth maps

    NASA Astrophysics Data System (ADS)

    Yao, Huimin; Chen, Yan; Ge, Chenyang

    2013-07-01

    The great advantage of Microsoft Kinect makes the depth acquisition real-time and inexpensive. But the depth maps directly obtained with the Microsoft Kinect device have absent regions and holes caused by optical factors. The noisy depth maps affect lots of complex tasks in computer vision. In order to improve the quality of the depth maps, this paper presents an efficient image inpainting strategy which is based on watershed segmentation and region merging framework of the corresponding color images. The primitive regions produced by watershed transform are merged into lager regions according to color similarity and edge among regions. Finally, mean filter operator to the adjacent pixels is used to fill up missing depth values and deblocking filter is applied for smoothing depth maps.

  5. Learning the missing values in depth maps

    NASA Astrophysics Data System (ADS)

    Yin, Xuanwu; Wang, Guijin; Zhang, Chun; Liao, Qingmin

    2013-12-01

    In this paper, we consider the task of hole filling in depth maps, with the help of an associated color image. We take a supervised learning approach to solve this problem. The model is learnt from the training set, which contain pixels that have depth values. Then we apply supervised learning to predict the depth values in the holes. Our model uses a regional Markov Random Field (MRF) that incorporates multiscale absolute and relative features (computed from the color image), and models depths not only at individual points but also between adjacent points. The experiments show that the proposed approach is able to recover fairly accurate depth values and achieve a high quality depth map.

  6. The stochastic variability of asteroidal regolith depths

    NASA Technical Reports Server (NTRS)

    Housen, K. R.

    1982-01-01

    Modeling the depth of regolith on asteroids is approached from a statistical point of view. It is demonstrated that average values are not good descriptors of regolith depth on asteroids. Large deviations from the average can be expected to occur due to both large variations in depth over the surface of a body and to the fact that each asteroid has a unique regolith. The utility of the average depth is not significantly increased by excluding the parts of a surface which are occupied by large craters; a procedure adopted in existing regolith models. Although an asteroid's surface may be 'smoothed out' by movement of debris into gravitationally low spots, the regolith depth retains its variability because of variations in topography at the bottom of the regolith layer. The large variability associated with regolith depth severely limits the power of regolith models in predicting parent body size for the brecciated meteorites.

  7. Power spectrum extraction for redshifted 21-cm Epoch of Reionization experiments: the LOFAR case

    NASA Astrophysics Data System (ADS)

    Harker, Geraint; Zaroubi, Saleem; Bernardi, Gianni; Brentjens, Michiel A.; de Bruyn, A. G.; Ciardi, Benedetta; Jelić, Vibor; Koopmans, Leon V. E.; Labropoulos, Panagiotis; Mellema, Garrelt; Offringa, André; Pandey, V. N.; Pawlik, Andreas H.; Schaye, Joop; Thomas, Rajat M.; Yatawatta, Sarod

    2010-07-01

    One of the aims of the Low Frequency Array (LOFAR) Epoch of Reionization (EoR) project is to measure the power spectrum of variations in the intensity of redshifted 21-cm radiation from the EoR. The sensitivity with which this power spectrum can be estimated depends on the level of thermal noise and sample variance, and also on the systematic errors arising from the extraction process, in particular from the subtraction of foreground contamination. We model the extraction process using realistic simulations of the cosmological signal, the foregrounds and noise, and so estimate the sensitivity of the LOFAR EoR experiment to the redshifted 21-cm power spectrum. Detection of emission from the EoR should be possible within 360 h of observation with a single station beam. Integrating for longer, and synthesizing multiple station beams within the primary (tile) beam, then enables us to extract progressively more accurate estimates of the power at a greater range of scales and redshifts. We discuss different observational strategies which compromise between depth of observation, sky coverage and frequency coverage. A plan in which lower frequencies receive a larger fraction of the time appears to be promising. We also study the nature of the bias which foreground fitting errors induce on the inferred power spectrum and discuss how to reduce and correct for this bias. The angular and line-of-sight power spectra have different merits in this respect, and we suggest considering them separately in the analysis of LOFAR data.

  8. Improved snow depth retrieval by combining SSM/I and MODIS data with SMO regression

    NASA Astrophysics Data System (ADS)

    Liang, J.; Huang, K.; Liu, X.; Li, X.

    2013-12-01

    The snow depth retrieval using passive microwave remote sensing heavily depends on the spatial and temporal snow characteristics. The acquisition of the snow parameters usually requires costly field work or complicated modeling. Given that snow characteristics can also be retrieved by visible/infrared sensors, the integration of microwave and visible/infrared data has the potential for improving the retrieval accuracy. The snow depth retrieval is performed by using microwave brightness temperature at 19 and 37 GHz from the Special Sensor Microwave / Imager (SSM/I) and surface visible/infrared reflectance from Moderate Resolution Imaging Spectroadiometer (MODIS) products. The microwave brightness temperature difference could help to estimate snow volume and the visible/infrared surface reflectance contains the information of snow grain size. With these integrated remote sensing data, snow depth is retrieved by a nonlinear data mining technique, the modified sequential minimal optimization (SMO) algorithm for support vector machine (SVM) regression. We tested the proposed method by using about 25000 records of snow depth measurements from 53 meteorological stations in Xinjiang from 2000 to 2010. The RMSE of SVM retrieved snow depth of our method is 6.49 cm and 0.73 respectively. They are better than those of using brightness temperature data solely (6.90 cm and 0.66), the traditional spectral polarization difference (SPD) algorithm (12.06 cm and 0.36), the modified Chang algorithm in WESTDC (8.51 cm and 0.57), and the multilayer perceptron classifier of artificial neural network (ANN) (7.08 cm and 0.63). The regional comparisons of the proposed method and the global snow products (GLOBSNOW and AMSR-E daily snow) are also presented. The study has shown that combining MODIS surface reflectance data and SSM/I brightness temperature with SVM regression can provide more accurate snow depth retrieval results. Experimental result of the proposed method in 2004

  9. Neutron depth profiling at the University of Texas

    NASA Astrophysics Data System (ADS)

    Ünlü, Kenan; Wehring, Bernard W.

    1994-12-01

    A Neutron Depth Profiling (NDP) facility has been developed at The University of Texas at Austin (UT) Nuclear Engineering Teaching Laboratory. Thermal neutrons from the tangential beam port of the UT 1-MW TRIGA Mark II research reactor are utilized. The UT-NDP facility consists of a neutron beam collimator, target chamber, beam catcher, and necessary data acquisition and process electronics. The collimator was designed to achieve a high quality thermal neutron beam with good intensity and minimum contamination of neutrons above thermal energies. A target chamber for NDP was constructed from 40.6 cm diameter aluminum tubing. The chamber can accommodate several small samples as well as a single large sample with a diameter up to 30.5 cm. Depth profiles for borophosphosilicate glass films on silicon wafers were measured using the UT-NDP facility. Other potential applications of the UT-NDP facility include the study of implanted boron in semiconductor material; study of nitrogen in metals; and study of helium behavior in metals, and metallic and amorphous alloys.

  10. Cold neutron depth profiling of lithium-ion battery materials

    NASA Astrophysics Data System (ADS)

    Lamaze, G. P.; Chen-Mayer, H. H.; Becker, D. A.; Vereda, F.; Goldner, R. B.; Haas, T.; Zerigian, P.

    We report the characterization of two thin-film battery materials using neutron techniques. Neutron depth profiling (NDP) has been employed to determine the distribution of lithium and nitrogen simultaneously in lithium phosphorous oxynitride (LiPON) deposited by ion beam assisted deposition (IBAD). The depth profiles are based on the measurement of the energy of the charged particle products from the 6Li(n,α) 3H and 14N(n,p) 14C reactions for lithium and nitrogen, respectively. Lithium at the level of 10 22 atoms/cm 3 and N of 10 21 atoms/cm 3, distributed in the film thickness on the order of 1 μm, have been determined. This information provides insights into nitrogen incorporation and lithium concentration in the films under various fabrication conditions. NDP of lithium has also been performed on IBAD LiCoO 2 films, in conjunction with instrumental neutron activation analysis (INAA) to determine the cobalt concentration. The Li/Co ratio thus obtained serves as an ex situ control for the thin-film evaporation process. The non-destructive nature of the neutron techniques is especially suitable for repeated analysis of these materials and for actual working devices.

  11. Altimeter error sources at the 10-cm performance level

    NASA Technical Reports Server (NTRS)

    Martin, C. F.

    1977-01-01

    Error sources affecting the calibration and operational use of a 10 cm altimeter are examined to determine the magnitudes of current errors and the investigations necessary to reduce them to acceptable bounds. Errors considered include those affecting operational data pre-processing, and those affecting altitude bias determination, with error budgets developed for both. The most significant error sources affecting pre-processing are bias calibration, propagation corrections for the ionosphere, and measurement noise. No ionospheric models are currently validated at the required 10-25% accuracy level. The optimum smoothing to reduce the effects of measurement noise is investigated and found to be on the order of one second, based on the TASC model of geoid undulations. The 10 cm calibrations are found to be feasible only through the use of altimeter passes that are very high elevation for a tracking station which tracks very close to the time of altimeter track, such as a high elevation pass across the island of Bermuda. By far the largest error source, based on the current state-of-the-art, is the location of the island tracking station relative to mean sea level in the surrounding ocean areas.

  12. Development of 14 cm Period Wiggler at PLS

    SciTech Connect

    Kim, D.E.; Park, K.H.; Lee, H.G.; Suh, H.S.; Han, H.S.; Jung, Y.G.; Chung, C.W.

    2004-05-12

    Pohang Accelerator Laboratory (PAL) is developing a 14 cm period wiggler (MPW14) for high flux material science(HFMS) beamline. The MPW14 is a hybrid type device achieving higher peak flux density. PLS MPW14 features period of 14cm, minimum gap of 14mm, 24 full field poles, maximum flux density of 2.02 Tesla, and the total magnetic structure length of 2056mm. The peak flux density is higher compared to the other wigglers of similar pole gap and period. The high peak flux density has been achieved by using advanced new magnetic materials and optimized magnetic geometry. The magnetic performance of the MPW14 is measured using a conventional hall probe scanning system and flipping coil system. The newly developed angularly resolved flipping coil measurement system is very precise and fast. Due to its angular resolving feature, all higher order multipole contents of the MPW14 could be measured. In this article, all the developments efforts for the PLS MPW14 wiggler and the efforts for the angularly resolving flipping coil measurement system are described.

  13. Presolar grains in the CM2 chondrite Sutter's Mill

    NASA Astrophysics Data System (ADS)

    Zhao, Xuchao; Lin, Yangting; Yin, Qing-Zhu; Zhang, Jianchao; Hao, Jialong; Zolensky, Michael; Jenniskens, Peter

    2014-11-01

    The Sutter's Mill (SM) carbonaceous chondrite is a regolith breccia, composed predominantly of CM2 clasts with varying degrees of aqueous alteration and thermal metamorphism. An investigation of presolar grains in four Sutter's Mill sections, SM43, SM51, SM2-4, and SM18, was carried out using NanoSIMS ion mapping technique. A total of 37 C-anomalous grains and one O-anomalous grain have been identified, indicating an abundance of 63 ppm for presolar C-anomalous grains and 2 ppm for presolar oxides. Thirty-one silicon carbide (SiC), five carbonaceous grains, and one Al-oxide (Al2O3) were confirmed based on their elemental compositions determined by C-N-Si and O-Si-Mg-Al isotopic measurements. The overall abundance of SiC grains in Sutter's Mill (55 ppm) is consistent with those in other CM chondrites. The absence of presolar silicates in Sutter's Mill suggests that they were destroyed by aqueous alteration on the parent asteroid. Furthermore, SM2-4 shows heterogeneous distributions of presolar SiC grains (12-54 ppm) in different matrix areas, indicating that the fine-grained matrix clasts come from different sources, with various thermal histories, in the solar nebula.

  14. Discovery and First Observations of the 21-cm Hydrogen Line

    NASA Astrophysics Data System (ADS)

    Sullivan, W. T.

    2005-08-01

    Unlike most of the great discoveries in the first decade of radio astronomy after World War II, the 21 cm hydrogen line was first predicted theoretically and then purposely sought. The story is familiar of graduate student Henk van de Hulst's prediction in occupied Holland in 1944 and the nearly simultaneous detection of the line by teams at Harvard, Leiden, and Sydney in 1951. But in this paper I will describe various aspects that are little known: (1) In van de Hulst's original paper he not only worked out possible intensities for the 21 cm line, but also for radio hydrogen recombination lines (not detected until the early 1960s), (2) in that same paper he also used Jansky's and Reber's observations of a radio background to make cosmological conclusions, (3) there was no "race" between the Dutch, Americans, and Australians to detect the line, (4) a fire that destroyed the Dutch team's equipment in March 1950 ironically did not hinder their progress, but actually speeded it up (because it led to a change of their chief engineer, bringing in the talented Lex Muller). The scientific and technical styles of the three groups will also be discussed as results of the vastly differing environments in which they operated.

  15. Power processor for a 20CM ion thruster

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Schoenfeld, A. D.; Cohen, E.

    1973-01-01

    A power processor breadboard for the JPL 20CM Ion Engine was designed, fabricated, and tested to determine compliance with the electrical specification. The power processor breadboard used the silicon-controlled rectifier (SCR) series resonant inverter as the basic power stage to process all the power to the ion engine. The breadboard power processor was integrated with the JPL 20CM ion engine and complete testing was performed. The integration tests were performed without any silicon-controlled rectifier failure. This demonstrated the ruggedness of the series resonant inverter in protecting the switching elements during arcing in the ion engine. A method of fault clearing the ion engine and returning back to normal operation without elaborate sequencing and timing control logic was evolved. In this method, the main vaporizer was turned off and the discharge current limit was reduced when an overload existed on the screen/accelerator supply. After the high voltage returned to normal, both the main vaporizer and the discharge were returned to normal.

  16. Electric prototype power processor for a 30cm ion thruster

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Inouye, L. Y.; Schoenfeld, A. D.

    1977-01-01

    An electrical prototype power processor unit was designed, fabricated and tested with a 30 cm mercury ion engine for primary space propulsion. The power processor unit used the thyristor series resonant inverter as the basic power stage for the high power beam and discharge supplies. A transistorized series resonant inverter processed the remaining power for the low power outputs. The power processor included a digital interface unit to process all input commands and internal telemetry signals so that electric propulsion systems could be operated with a central computer system. The electrical prototype unit included design improvement in the power components such as thyristors, transistors, filters and resonant capacitors, and power transformers and inductors in order to reduce component weight, to minimize losses, and to control the component temperature rise. A design analysis for the electrical prototype is also presented on the component weight, losses, part count and reliability estimate. The electrical prototype was tested in a thermal vacuum environment. Integration tests were performed with a 30 cm ion engine and demonstrated operational compatibility. Electromagnetic interference data was also recorded on the design to provide information for spacecraft integration.

  17. Measuring the Cosmological 21 cm Monopole with an Interferometer

    NASA Astrophysics Data System (ADS)

    Presley, Morgan E.; Liu, Adrian; Parsons, Aaron R.

    2015-08-01

    A measurement of the cosmological 21 {cm} signal remains a promising but as-of-yet unattained ambition of radio astronomy. A positive detection would provide direct observations of key unexplored epochs of our cosmic history, including the cosmic dark ages and reionization. In this paper, we concentrate on measurements of the spatial monopole of the 21 {cm} brightness temperature as a function of redshift (the “global signal”). Most global experiments to date have been single-element experiments. In this paper, we show how an interferometer can be designed to be sensitive to the monopole mode of the sky, thus providing an alternate approach to accessing the global signature. We provide simple rules of thumb for designing a global signal interferometer and use numerical simulations to show that a modest array of tightly packed antenna elements with moderately sized primary beams (FWHM of ∼ 40^\\circ ) can compete with typical single-element experiments in their ability to constrain phenomenological parameters pertaining to reionization and the pre-reionization era. We also provide a general data analysis framework for extracting the global signal from interferometric measurements (with analysis of single-element experiments arising as a special case) and discuss trade-offs with various data analysis choices. Given that interferometric measurements are able to avoid a number of systematics inherent in single-element experiments, our results suggest that interferometry ought to be explored as a complementary way to probe the global signal.

  18. Characterization of an 8-cm Diameter Ion Source System

    NASA Technical Reports Server (NTRS)

    Li, Zhongmin; Hawk, C. W.; Hawk, Clark W.; Buttweiler, Mark S.; Williams, John D.; Buchholtz, Brett

    2005-01-01

    Results of tests characterizing an 8-cm diameter ion source are presented. The tests were conducted in three separate vacuum test facilities at the University of Alabama-Huntsville, Colorado State University, and L3 Communications' ETI division. Standard ion optics tests describing electron backstreaming and total-voltage-limited impingement current behavior as a function of beam current were used as guidelines for selecting operating conditions where more detailed ion beam measurements were performed. The ion beam was profiled using an in-vacuum actuating probe system to determine the total ion current density and the ion charge state distribution variation across the face of the ion source. Both current density and ExB probes were utilized. The ion current density data were used to obtain integrated beam current, beam flatness parameters, and general beam profile shapes. The ExB probe data were used to determine the ratio of doubly to singly charged ion current. The ion beam profile tests were performed at over six different operating points that spanned the expected operating range of the DAWN thrusters being developed at L3. The characterization tests described herein reveal that the 8-cm ion source is suitable for use in (a) validating plasma diagnostic equipment, (b) xenon ion sputtering and etching studies of spacecraft materials, (c) plasma physics research, and (d) the study of ion thruster optics at varying conditions.

  19. Single-Photon Depth Imaging Using a Union-of-Subspaces Model

    NASA Astrophysics Data System (ADS)

    Shin, Dongeek; Shapiro, Jeffrey H.; Goyal, Vivek K.

    2015-12-01

    Light detection and ranging systems reconstruct scene depth from time-of-flight measurements. For low light-level depth imaging applications, such as remote sensing and robot vision, these systems use single-photon detectors that resolve individual photon arrivals. Even so, they must detect a large number of photons to mitigate Poisson shot noise and reject anomalous photon detections from background light. We introduce a novel framework for accurate depth imaging using a small number of detected photons in the presence of an unknown amount of background light that may vary spatially. It employs a Poisson observation model for the photon detections plus a union-of-subspaces constraint on the discrete-time flux from the scene at any single pixel. Together, they enable a greedy signal-pursuit algorithm to rapidly and simultaneously converge on accurate estimates of scene depth and background flux, without any assumptions on spatial correlations of the depth or background flux. Using experimental single-photon data, we demonstrate that our proposed framework recovers depth features with 1.7 cm absolute error, using 15 photons per image pixel and an illumination pulse with 6.7-cm scaled root-mean-square length. We also show that our framework outperforms the conventional pixelwise log-matched filtering, which is a computationally-efficient approximation to the maximum-likelihood solution, by a factor of 6.1 in absolute depth error.

  20. The effect of burial depth on removal of seeds of Phytolacca americana.

    SciTech Connect

    Orrock, John, L.: Damschen, Ellen, I.

    2007-04-01

    Abstract - Although burial is known to have important effects on seed predation in a variety of habitats, the role of burial depth in affecting the removal of seeds in early successional systems is poorly known. Phytolacca American (pokeweed) is a model species to examine the role of burial depth in affecting seed removal because it is common in early-successional habitats, studies suggest that seed removal is indicative of seed predation, and seed predation is related to the recruitment of mature plants. To determine how burial depth affects P. americana seed removal, 20 seeds of P. americana were buried at depths of 0, 1, or 3 cm in early-successional habitats at the Savannah River Site in South Carolina for over 6 weeks. The frequency with which seeds were encountered (as measured by the removal of at least one seed) and the proportion of seeds removed was significantly greater when seeds were on the soil surface (0 cm depth) compared to seeds that were buried 1 cm or 3 cm; there was no difference in encounter or removal between seeds at 1 cm or 3 cm. Our findings suggest that burial may have important consequences for P. americana population dynamics, because seed survival depends upon whether or not the seed is buried, and relatively shallow burial can yield large increases in seed survival. Because seed limitation is known to be an important determinant of plant community composition in early successional systems, our work suggests that burial may play an unappreciated role in the dynamics of these communities by reducing predator-mediated seed limitation.