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Sample records for 0-15 cm soil

  1. Poliovirus retention in 75-cm soil cores after sewage and rainwater application

    SciTech Connect

    Landry, E.F.; Vaughn, J.M.; Penello, W.F.

    1980-12-01

    The adsorption rate of a guanidine-resistant strain of poliovirus LSc 2ab was measured in Long Island soils with in situ field cores (10.1 by 75 cm). The test virus was chosen because it exhibited soil adsorption and elution characteristics of a number of non-polioviruses. After the inoculation of cores with seeded sewage effluent at a 1-cm/h infiltration rate, cores were extracted, fractionated, and analyzed for total plaque-forming units per each 5-cm fraction. The results showed that 77% of the viruses were adsorbed in the first 5 cm of soil. An additional 11% were found in the 5- to 10-cm fraction, and a total of 96% of the viruses were adsorbed by 25 cm. The remaining 4% were uniformly distributed over the next 50 cm of soil, with a minimum of 0.23% in each soil section. Few viruses (< 0.22%) were observed in core filtrates. Analysis of the viral distribution pattern in seeded cores, after an application of a single rinse of either sewage effluent or rainwater, indicated that large-scale viral mobilization was absent. However, localized areas of viral movement were noted in both of the rinsed cores, with the rainwater rinsed cores exhibiting more extensive movement. All mobilized viruses were resorbed at lower core depths.

  2. 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...

  3. 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.

  4. Assessing soil hydrological variability at the cm- to dm-scale using air permeameter measurements

    NASA Astrophysics Data System (ADS)

    Beerten, K.; Vandersmissen, N.; Rogiers, B.; Mallants, D.

    2012-04-01

    Soils and surficial sediments are crucial elements in the hydrological cycle since they are the medium through which infiltrating precipitation percolates to the aquifer. At the same time, soil horizons and shallow stratigraphy may act as hydraulic barriers that can promote runoff or interflow and hamper deep infiltration. For most catchments little is known about the small-scale horizontal and vertical variability of soil hydrological properties. Such information is however required to calculate detailed soil water flow paths and estimate small scale spatial variability in recharge and run-off. We present the results from field air permeameter measurements to assess the small-scale variability of saturated hydraulic conductivity in heterogeneous 2-D soil profiles. To this end, several outcrops in the unsaturated zone (sandy soils with podzolisation) of an interfluve in the Kleine Nete river catchment (Campine area, Northern Belgium) were investigated using a hand-held permeameter. Measurements were done each 10 cm on ~ 2 x 1 m or ~ 2 x 0.5 m grids. The initial results of the measurements (air permeability Kair; millidarcy) are recalculated to saturated hydraulic conductivity (Ks; m/s) using specific transfer functions (Loll et al., 1999; Iversen et al., 2003). Validation of the results is done with independent lab-based constant head Ks measurements. The results show that field based Ks values generally range between 10-3 m/s and 10-7 m/s within one profile, but extremely high values (up to 10-1 m/s) have been measured as well. The lowest values are found in the organic- and silt-rich Bh horizon of podzol soils observed within the profiles (~ 10-6-10-7m/s), while the highest values are observed in overlying dune sands less than 40 cm deep (up to 10-3 m/s with outliers to 10-1 m/s). Comparison of field and laboratory based Ks data reveals there is fair agreement between both methods, apart from several outliers. Scatter plots indicate that almost all points

  5. Thermal emission measurements 2000-400/cm (5-25 micrometers) of Hawaiian palagonitic soils and their implications for Mars

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Bell, James F., III

    1995-01-01

    The thermal emision of two palagonitic soils, common visible and near infrared spectral analogs for bright soils on Mars, was measured over the wavelength range of 5 to 25 micrometers (2000 to 400/cm) for several partical size separates. All spectra exhibit emissivity features due to vibrations associated with H2O and SiO. The maximum variability of emissivity is approximately 20% in the short wavelength region (5 to 6.5 mirometers, 2000 to 1500/cm), and is more subdued, less than 4%, at longer wavelengths. The strengths of features present in the infrared spectra of Mars cannot be solely provided by emissivity variations of palagonite; some other material or mechanism must provide additional absorptions(s).

  6. 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...

  7. Comparison of 2.8- and 21-cm microwave radiometer observations over soils with emission model calculations

    NASA Technical Reports Server (NTRS)

    Burke, W. J.; Schmugge, T.; Paris, J. F.

    1979-01-01

    An airborne experiment was conducted under NASA auspices to test the feasibility of detecting soil moisture by microwave remote sensing techniques over agricultural fields near Phoenix, Arizona at midday of April 5, 1974 and at dawn of the following day. Extensive ground data were obtained from 96 bare, sixteen hectare fields. Observations made using a scanning (2.8 cm) and a nonscanning (21 cm) radiometer were compared with the predictions of a radiative transfer emission model. It is shown that (1) the emitted intensity at both wavelengths correlates best with the near surface moisture, (2) surface roughness is found to more strongly affect the degree of polarization than the emitted intensity, (3) the slope of the intensity-moisture curves decreases in going from day to dawn, and (4) increased near surface moisture at dawn is characterized by increased polarization of emissions. The results of the experiment indicate that microwave techniques can be used to observe the history of the near surface moisture. The subsurface history must be inferred from soil physics models which use microwave results as boundary conditions.

  8. Diagnosing the strength of soil temperature in the land atmosphere interactions over Asia based on RegCM4 model

    NASA Astrophysics Data System (ADS)

    Liu, Di; Yu, Zhongbo; Zhang, Jianyun

    2015-07-01

    This study aims to investigate the soil temperature atmosphere (ST Atm) coupling strength and their influence on the subsequent climate anomalies over Asia based on a regional climate model RegCM4 with both statistical analysis method and numerical experiments. The major findings are as follows: (1) The soil temperature precipitation (ST P) coupling is quite weak and spatially scattered from both RegCM4 output and GLDAS data in each season with the only obvious signals existing over the north India region in summer season according to the RegCM4 output; the soil temperature 2m air temperature (ST T2m) coupling is strong and spatially continuous with the India (in spring, summer and autumn seasons), South Indochina (in spring and summer seasons) and part of North China (in summer season) standing out as hotspots. (2) The soil temperature evapotranspiration (ST ET) and soil temperature evaporative fraction (ST EF) coupling almost resembles the same spatial patterns and magnitude in each season. Both the ET and EF play an important role in linking ST P coupling in each season, but not in the ST T2m coupling. The hotspots of ST T2m coupling outweigh the areas with strong ST ET and ST EF coupling. Only the India and Indochina in each season are recognized by the RegCM4 while the Indochina and west Asia in spring, north India, Indochina and part of mid-high latitudes in summer season pinpointed by GLDAS data show consistent strong ST T2m coupling with significant ST ET and ST EF coupling. This finding demonstrates the complicated ST Atm coupling. (3) The ST anomalies prescribed at the first step of each season can only persist a short time (within 5 days) over most part of the study area while the fixed one-month anomalies can last longer (approximately 2 months with colder anomalies and 45 days with warmer anomalies in tropical regions). (4) The impact of ST anomalies on subsequent precipitation is quite weak and can be ignored over most part of the study area, while

  9. Herbicide sorption coefficients in relation to soil properties and terrain attributes on a cultivated prairie

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sorption of the herbicides 2,4-D and glyphosate in soil was quantified for 286 surface soil samples (0-15 cm) collected in a 10 m X 10 m grid across a heavily-eroded undulating calcareous prairie landscape. At each sampling point soil organic carbon content, soil carbonate content, soil pH, till...

  10. Thermal emission measurements 2000-400 cm(exp -1) (5-25 microns) of Hawaiian palagonitic soils and their implications for Mars

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Bell, James F., III

    1995-01-01

    The thermal emission of two palagonitic soils, common visible and near infrared spectral analogs for bright soils on Mars, was measured over the wavelength range of 5 to 25 microns (2000 to 400 cm(exp -1) for several particle size separates. All spectra exhibit emissivity features due to vibrations associated with H2O and SiO. The maximum variability of emissivity is approx. = 20% in the short wavelength region (5 to 6.5 microns, 2000 to 1500 cm(exp -1)), and is more subdued, < 4%, at longer wavelengths. The strengths of features present in infrared spectra of Mars cannot be solely provided by emissivity variations of palagonite; some other material or mechanism must provide additional absorption(s).

  11. Influence of soil moisture on soil respiration

    NASA Astrophysics Data System (ADS)

    Fer, Miroslav; Kodesova, Radka; Nikodem, Antonin; Klement, Ales; Jelenova, Klara

    2015-04-01

    The aim of this work was to describe an impact of soil moisture on soil respiration. Study was performed on soil samples from morphologically diverse study site in loess region of Southern Moravia, Czech Republic. The original soil type is Haplic Chernozem, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). Soil samples were collected from topsoils at 5 points of the selected elevation transect and also from the parent material (loess). Grab soil samples, undisturbed soil samples (small - 100 cm3, and large - 713 cm3) and undisturbed soil blocks were taken. Basic soil properties were determined on grab soil samples. Small undisturbed soil samples were used to determine the soil water retention curves and the hydraulic conductivity functions using the multiple outflow tests in Tempe cells and a numerical inversion with HYDRUS 1-D. During experiments performed in greenhouse dry large undisturbed soil samples were wetted from below using a kaolin tank and cumulative water inflow due to capillary rise was measured. Simultaneously net CO2 exchange rate and net H2O exchange rate were measured using LCi-SD portable photosynthesis system with Soil Respiration Chamber. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program was applied to modify selected soil hydraulic parameters for particular conditions and to simulate actual soil water distribution within each soil column in selected times. Undisturbed soil blocks were used to prepare thin soil sections to study soil-pore structure. Results for all soil samples showed that at the beginning of soil samples wetting the CO2 emission increased because of improving condition for microbes' activity. The maximum values were reached for soil column average soil water content between 0.10 and 0.15 cm3/cm3. Next CO2 emission decreased since the pore system starts filling by water (i.e. aggravated conditions for microbes

  12. Sampling depth confounds soil acidification outcomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the northern Great Plains (NGP) of North America, surface sampling depths of 0-15 or 0-20 cm are suggested for testing soil characteristics such as pH. However, acidification is often most pronounced near the soil surface. Thus, sampling deeper can potentially dilute (increase) pH measurements an...

  13. Depth Matters: Soil pH and dilution effects in the northern Great Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the northern Great Plans (NGP), surface sampling depths of 0-15.2 cm or 0-20.3 cm are suggested for testing soil characteristics such as pH. However, acidification is often most pronounced near-surface (e.g., <10 cm). Thus, sampling deeper can potentially dilute (increase) pH measurements and the...

  14. [Effects of soil thickness on spatiotemporal pattern of soil moisture in catchment level].

    PubMed

    Chen, Jia; Shi, Zhi-Hua; Li, Lu; Luo, Xuan

    2009-07-01

    Based on the fixed-spot observation, this paper analyzed the effects of soil thicknesses on the spatiotemporal pattern of soil moisture in the Wulongchi catchment of Danjiangkou, China. The soil moisture content increased soon after precipitation events, followed by a decline as the soil dried down, whilst its spatial heterogeneity exhibited an opposite pattern. The profile-averaged soil moisture content differed significantly with soil thickness. The soil with a thickness of 20 cm had lower profile-averaged moisture content whose variation trend was similar to that of precipitation and varied obviously among seasons; medium thickness (20-40 cm) soil had medium level of profile-averaged moisture content whose seasonal variation was moderately and affected by the characteristics of precipitation; while the soil with a thicknesses of > 40 cm had higher profile-averaged moisture content whose seasonal variation was relatively small. The profile distribution pattern of soil moisture was determined by the integrated effects of precipitation, evapotranspiration, and leakage, exhibiting increasing-type at semi-humid stage, waving-type at humid stage, and both of the two types at arid stage. There was a significant positive correlation between profile-averaged soil moisture content and soil thickness, and the correlation coefficient was 0.630-0.855. The moisture content in 0-15 cm soil layer had less correlation with soil thickness, but the moisture content in 20-55 cm soil layer was significantly correlated with soil thickness.

  15. Peculiarities of ionic transport in Li1.3Al0.15Y0.15Ti1.7(PO4)3 ceramics

    NASA Astrophysics Data System (ADS)

    Šalkus, T.; Kazakevičius, E.; Kežionis, A.; Dindune, A.; Kanepe, Z.; Ronis, J.; Emery, J.; Boulant, A.; Bohnke, O.; Orliukas, A. F.

    2009-05-01

    A powder of Li1.3Al0.15Y0.15Ti1.7(PO4)3 has been synthesized by solid state reaction. The powder was a single phase material and had rhombohedral symmetry (space group R\\bar {3}c ) with six formula units in the unit cell. Impedance spectra of Li1.3Al0.15Y0.15Ti1.7(PO4)3 ceramics were recorded in the frequency range from 106 to 1.2 × 109 Hz and temperature range from 300 to 600 K. Two relaxation type dispersions of electrical quantities in the frequency range were found. The dispersion regions are presumably related to the ionic transport processes in bulk and grain boundaries of the ceramics. The activation energy of the conductivity of the bulk and the activation energy of the characteristic relaxation frequency, at which the dispersion sets in, has the same value of 0.25 eV. The only contribution of the mobility of Li+ ions defines the temperature dependence of the bulk conductivity in the investigated temperature range. The values of ɛ' may be related to the contributions of the polarization of the fast ionic migration, vibrations of the lattice and electronic polarization. Nuclear magnetic resonance (NMR) investigation shows that the T1 of 7Li and 6Li at room temperature are 6 ms and 2 s respectively. This result confirms that the relaxation of the 7Li nucleus occurs through quadrupolar fluctuations although the relaxation of the 6Li nucleus occurs via dipolar fluctuations. Furthermore, the T1 minimum allows us to evidence a motion with a characteristic frequency in the range of the Larmor frequency.

  16. 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

  17. Chernobyl fallout in the uppermost (0-3 cm) humus layer of forest soil in Finland, North East Russia and the Baltic countries in 2000--2003.

    PubMed

    Ylipieti, J; Rissanen, K; Kostiainen, E; Salminen, R; Tomilina, O; Täht, K; Gilucis, A; Gregorauskiene, V

    2008-12-15

    The situation resulting from the Chernobyl fallout in 1987 was compared to that in 2000--2001 in Finland and NW Russia and that in 2003 in the Baltic countries. 786 humus (0-3 cm layer) samples were collected during 2000--2001 in the Barents Ecogeochemistry Project, and 177 samples in the Baltic countries in 2003. Nuclides emitting gamma-radiation in the 0-3 cm humus layer were measured by the Radiation and Nuclear Safety Authority-STUK in Finland. In 1987 the project area was classified by the European Commission into four different fallout classes. 137Cs inventory Bg/m2 levels measured in 2000--2003 were compared to the EU's class ranges. Fitting over the whole project area was implemented by generalizing the results for samples from the Baltic countries, for which Bq/m2 inventories could be calculated. A rough estimation was made by comparing the mass of organic matter and humus with 137Cs concentrations in these two areas. Changes in 137Cs concentration levels are illustrated in both thematic maps and tables. Radionuclide 137Cs concentrations (Bq/kg d.w.) were detected in the humus layer at all the 988 sampling sites. 134Cs was still present in 198 sites 15 years after the nuclear accident in Chernobyl. No other anthropogenic nuclides emitting gamma-radiation were detected, but low levels of 60Co, 125Sb and 154Eu isotopes were found in 14 sites. Fifteen years after the Chernobyl accident, the radioactive nuclide 137Cs was and still is the most significant fallout radionuclide in the environment and in food chains. The results show that the fallout can still be detected in the uppermost humus layer in North East Europe.

  18. Soil 13C Dynamics in Aggregates Across a Soil Profile Under an Established Miscanthus System

    NASA Astrophysics Data System (ADS)

    Dondini, M.; Groenigen, K. J.; Jones, M.

    2008-12-01

    Soils are the largest pool of terrestrial organic carbon (C), containing nearly three times the amount of C as the atmosphere. Environmental changes that affect soil C dynamics could slow down the rise in atmospheric CO2 and associated warming by promoting soil C storage. Our capacity to predict the consequences for global change therefore depends on a better understanding of the distribution and controls of soil organic C and how vegetation change may affect SOC distributions. One land cover change of particular interest involves the establishment of bio energy crop stands. The full mitigation potential of bio energy crops cannot be considered without taking into account their effect on soil C dynamics. Miscanthus, a perennial C4 grass from Eastern Asia, has recently received considerable interest as a bio-energy crop. For that reason, we analyzed the C content and the 13C signatures across the soil profile in a 14 year old Miscanthus system, established on former arable land. We combined SOM fractionation techniques by size and density, allowing us to investigate small shifts in soil C stores that would be significant in the long term, but that might not be detected by conventional methodologies. The 13C signal of the various SOM fractions allowed us to distinguish between Miscanthus-derived vs. native soil organic C. Soils under Miscanthus contained 796 g C/m2 in the 0-15 cm layer, and 1233g C/m2 in the 15- 30 cm layer. These values are significantly higher than soil C contents in the arable land. Macroaggregates under Miscanthus contain more than twice as much C compared to arable land, showing a decrease in soil C content with decreasing aggregate size. These differences are largely caused by soil C storage in the microaggregate within macroaggregates fraction. Under Miscanthus, this fraction contains 440 g C/m2 and 488 g C/m2 at 0-15 cm and 15-30 cm respectively, while under the arable land it has mean values of 174 g C/m2 and 353 g C/m2. Our data suggest a

  19. 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.

  20. Electronic structure of (Ca0.85La0.15)FeAs2

    NASA Astrophysics Data System (ADS)

    Liu, Z.-H.; Kim, T. K.; Sala, A.; Ogino, H.; Shimoyama, J.; Büchner, B.; Borisenko, S. V.

    2015-02-01

    We report a comprehensive study of orbital character and tridimensional nature of the electronic structure of (Ca0.85La0.15)FeAs2 from recently discovered "112" family of Iron-based superconductors (IBS), with angle-resolved photoemission spectroscopy. We observed that the band structure is similar to that of "122" family, namely, there are three hole-like bands at the Brillouin zone (BZ) center and two electron-like bands at the BZ corner. The bands near the Fermi level (EF) are mainly derived from the Fe t2g orbitals. On the basis of our present and earlier studies, we classify IBS into the three types according to their crystal structures. We show that although the bands near EF mainly originate from Fe 3d electrons, they are significantly modified by the interaction between the superconducting slabs and the intermediate atoms.

  1. High Curie temperature Bi(1.85)Mn(0.15)Te3 nanoplates.

    PubMed

    Cheng, Lina; Chen, Zhi-Gang; Ma, Song; Zhang, Zhi-dong; Wang, Yong; Xu, Hong-Yi; Yang, Lei; Han, Guang; Jack, Kevin; Lu, Gaoqing Max; Zou, Jin

    2012-11-21

    Bi(1.85)Mn(0.15)Te(3) hexagonal nanoplates with a width of ~200 nm and a thickness of ~20 nm were synthesized using a solvothermal method. According to the structural characterization and compositional analysis, the Mn(2+) and Mn(3+) ions were found to substitute Bi(3+) ions in the lattice. High-level Mn doping induces significant lattice distortion and decreases the crystal lattice by 1.07% in the a axis and 3.18% in the c axis. A high ferromagnetic state with a Curie temperature of ~45 K is observed in these nanoplates due to Mn(2+) and Mn(3+) ion doping, which is a significant progress in the field of electronics and spintronics.

  2. 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)

  3. Anisotropy in SmFeAsO0.8F0.15 single crystal

    NASA Astrophysics Data System (ADS)

    Pattanaik, A.; Nayak, P.

    2013-06-01

    The high temperature superconductors in the mixed state rounding superconducting transition temperature have been explained by using anisotropic London theory as well as GL-equation. Due to strong overlapping of vortices at higher fields the super electron density varies in space and London theory fails to explain. For lower critical field with in London limit and temperature close to transition, GL-approach with phenomenological mass tensor can be approximated for studying mixed state behavior. Expressing bare penetration depth λ into effective penetration depth λeff such as λeff2=λ2/f2 = λ2/1-b;f = 1-b and b = ba/Bc2, the high field behavior can be observed using 3D-anisotropic London theory by incorporating vortex overlapping. FeAs superconductors have distinguishing macroscopic properties such as an enormous upper critical field with low superconducting anisotropy and that leads the investigation of topology in the microscopic length scale. Particularly, the variation of specific heat as well as entropy in SmFeAsO0.8F0.15 has been verified by the GL-theory in London limit with vortex overlapping correction and found satisfactory result with the experimental findings.

  4. 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.

  5. Effects of grazing intensity on soil labile organic carbon fractions in a desert steppe area in Inner Mongolia.

    PubMed

    Cao, Jixin; Wang, Xiaoping; Sun, Xiangyang; Zhang, Lin; Tian, Yun

    2013-01-01

    Grazing can cause changes in soil carbon (C) level. This study aimed to elucidate the response of soil labile organic carbon (SLOC) under four different grazing intensities: non grazing (NG), 0 sheep·ha(-1); light grazing (LG), 0.91 sheep·ha(-1); moderate grazing (MG), 1.82 sheep·ha(-1), and heavy grazing (HG), 2.73 sheep·ha(-1). Results showed that there was no significant difference in total soil organic carbon (TOC) and soil inorganic carbon (SIC) content from three soil depths (0-15 cm, 15-30 cm, and 30-45 cm) under different grazing intensities. However, the SLOC including particulate organic carbon (POC), light fraction organic carbon (LFOC), and readily oxidizable carbon (ROC) content at a depth of 0-15 cm decreased with the increasing grazing intensity among LG, MG and HG. The SLOC content at depths of 15-30 cm under the NG and LG were significantly higher than that under the MG and the HG. The TOC and SLOC content decreased with increasing depths of soil horizons, but SIC content increased. The variation trend of the density of different soil carbon fractions and the ratio of individual SLOC fractions to TOC were similar to that of the soil carbon content of corresponding fractions. These results indicated that MG and HG treatments caused C loss at 0-30 cm; and SLOC was more sensitive than TOC in response to different grazing intensities.

  6. 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.

  7. Magnetic contribution of Bi0.85La0.15FeO3 in (1-x)Bi0.85La0.15FeO3-(x)CoFe2O4 nanocomposite powders

    NASA Astrophysics Data System (ADS)

    Han, Ru-shuai; Qi, Li-qian; Hou, Xue; Liu, Li-hu; Liu, Hui-yuan; Xian, Xiao-Ning; Guo, Ge-Xin; Sun, Hui-yuan

    2016-12-01

    In this work, a solid phase reaction method was used to fabricate (1-x)Bi0.85La0.15FeO3-xCoFe2O4 (x=0.1, 0.2, 0.3, 0.4) composite powders. X-ray diffraction patterns showed that no chemical reaction occurred between the separate Bi0.85La0.15FeO3 and CoFe2O4 phases and indicated that the powder samples had two distinct phases with a CoFe2O4 spinel phase and a Bi0.85La0.15FeO3 perovskite phase. The average crystallite sizes of the Bi0.85La0.15FeO3 in the composite powder were almost unchanged as the CoFe2O4 content was increased. By comparing the experimental and theoretical values for the magnetization, we found that the Bi0.85La0.15FeO3 phase contributed to the magnetization of the composite powders. In addition, it also provides a new way to prove the existence of magnetoelectric coupling in the sample.

  8. Spatial variability of soil salinity in coastal saline soil at different scales in the Yellow River Delta, China.

    PubMed

    Wang, Zhuoran; Zhao, Gengxing; Gao, Mingxiu; Chang, Chunyan

    2017-02-01

    The objectives of this study were to explore the spatial variability of soil salinity in coastal saline soil at macro, meso and micro scales in the Yellow River delta, China. Soil electrical conductivities (ECs) were measured at 0-15, 15-30, 30-45 and 45-60 cm soil depths at 49 sampling sites during November 9 to 11, 2013. Soil salinity was converted from soil ECs based on laboratory analyses. Our results indicated that at the macro scale, soil salinity was high with strong variability in each soil layer, and the content increased and the variability weakened with increasing soil depth. From east to west in the region, the farther away from the sea, the lower the soil salinity was. The degrees of soil salinization in three deeper soil layers are 1.14, 1.24 and 1.40 times higher than that in the surface soil. At the meso scale, the sequence of soil salinity in different topographies, soil texture and vegetation decreased, respectively, as follows: depression >flatland >hillock >batture; sandy loam >light loam >medium loam >heavy loam >clay; bare land >suaeda salsa >reed >cogongrass >cotton >paddy >winter wheat. At the micro scale, soil salinity changed with elevation in natural micro-topography and with anthropogenic activities in cultivated land. As the study area narrowed down to different scales, the spatial variability of soil salinity weakened gradually in cultivated land and salt wasteland except the bare land.

  9. 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

  10. 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

    2009-07-17

    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.

  11. Soil respiration in apple orchards, poplar plantations and adjacent grasslands in Artvin, Turkey.

    PubMed

    Tufekcioglu, Aydin; Ozbayram, Ali Kemal; Kucuk, Mehmet

    2009-09-01

    In this study influence of land-use type on soil respiration was investigated in poplar plantation, apple orchard (apple trees with understory grasses) and adjacent grassland sites in Seyitler Area, Artvin, Turkey. Soil respiration was measured approximately monthly in three sampling plots in each land use type from January 2005 to November 2005 using the soda-lime technique. Mean daily soil respiration ranged from 0.63-3.59 g Cm(-2) d(-1). Mean soil respiration in apple orchard, poplar plantation and grassland sites were 1.98, 1.45 and 1.12 g C m(-2) d(-1), respectively. Mean soil respiration was significantly greater in apple orchard than in poplar plantations and grasslands. Seasonal changes in soil respiration were related to soil moisture and temperature changes. Mean soil respiration rate correlated strongly with subsurface soil (15-35cm) pH (R = -0,73; p < 0.05), sand content (R = 0.96, p < 0.001), soil silt content (R = -0.75; p < 0.05), soil clay content (R = -0.83; p < 0.001) and organic matter content (R = 0.88; p < 0.001). No significant correlations were observed between soil respiration and surface (0-15 cm) soil properties and root biomass. Overall, our results indicate that apple orchards with understory grasses have higher soil biological activity compared to poplar and grassland sites.

  12. Logistics Company Carrier Partner 2.0.15 Tool: Technical Documentation 2015 Data Year - United States Version

    EPA Pesticide Factsheets

    This SmartWay Logistics 2.0.15 Tool is intended to help logistics companies estimate and assess their carbon, PM, and NOx emission performance levels as well as their total emissions associated with goods movement in the U.S. freight rail, barge, air and t

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. PHASE TRANSITION, DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF NaNbO3-Ba0.85Ca0.15(Ti0.9Zr0.1)O3 LEAD-FREE CERAMICS

    NASA Astrophysics Data System (ADS)

    Lei, Yuqing; Wu, Hong; Lin, Dunmin; Zheng, Qiaoji; Wu, Xiaochun; Fan, Ximing

    2012-09-01

    A new lead-free solid solution of (1-x)NaNbO3-xBa0.85Ca0.15(Ti0.9Zr0.1)O3 was prepared by a traditional sintering method and its phase transition, dielectric and piezoelectric properties were studied. Ba0.85Ca0.15(Ti0.9Zr0.1)O3 diffuses into NaNbO3 lattices to form a new solid solution with perovskite structure. The addition of Ba0.85Ca0.15(Ti0.9Zr0.1)O3(x≥0.025) transforms NaNbO3 from antiferroelectric to ferroelectric. The diffusive ferroelectric-paraelectric phase transition is induced in the ceramics with high concentration of Ba0.85Ca0.15(Ti0.9Zr0.1)O3. The ceramics with x = 0.05-0.125 possess large Pr values of 18.6-25.5 μC/cm2. A morphotropic phase boundary between tetragonal and orthorhombic phases is formed at 0.05 < x < 0.15, leading to a significant enhancement of piezoelectric properties. The ceramic with x = 0.125 situated near the morphotropic phase boundary exhibits the optimum piezoelectric properties: d33 = 151 pC/N and kp = 31.6%.

  19. 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.

  20. Short-term grazing exclusion has no impact on soil properties and nutrients of degraded alpine grassland in Tibet, China

    NASA Astrophysics Data System (ADS)

    Lu, X.; Yan, Y.; Sun, J.; Zhang, X.; Chen, Y.; Wang, X.; Cheng, G.

    2015-11-01

    Since the 1980s, alpine grasslands have been seriously degraded on the Tibetan Plateau. Grazing exclusion by fencing has been widely adopted to restore degraded grasslands. To clarify the effect of grazing exclusion on soil quality, we investigated soil properties and nutrients by comparing free-grazing (FG) and grazing exclusion (GE) grasslands in Tibet. Soil properties - including soil bulk density, pH, particle size distributions, and proportion of aggregates - showed no significant difference between FG and GE plots. Soil organic carbon, soil available nitrogen, and available phosphorus contents did not differ with grazing exclusion treatments in both the 0-15 and 15-30 cm layer. However, soil total nitrogen and total phosphorus contents were remarkably reduced due to grazing exclusion at 0-15 cm depth. Furthermore, growing season temperature and/or growing season precipitation had significant effects on almost all soil property and nutrient indicators. This study demonstrates that grazing exclusion had no impact on most soil properties and nutrients in Tibet. Additionally, the potential shift of climate conditions should be considered when recommending any policy designed for restoration of degraded soil in alpine grasslands in the future. Nevertheless, because the results of the present study come from a short-term (6-8 years) grazing exclusion, the assessments of the ecological effects of the grazing exclusion management strategy on soil quality of degraded alpine grasslands in Tibet still need long-term continued research.

  1. Short-term grazing exclusion has no impact on soil properties and nutrients of degraded alpine grassland in Tibet, China

    NASA Astrophysics Data System (ADS)

    Lu, X.; Yan, Y.; Sun, J.; Zhang, X.; Chen, Y.; Wang, X.; Cheng, G.

    2015-08-01

    Since the 1980s, alpine grasslands have been seriously degraded on the Tibetan Plateau. Grazing exclusion by fencing has been widely adopted to restore degraded grasslands. To clarify the effect of grazing exclusion on soil quality, we investigated soil properties and nutrients by comparing free grazing (FG) and grazing exclusion (GE) grasslands in Tibet. Soil properties, including soil bulk density, pH, particle size distributions, and proportion of aggregates, were not significant different between FG and GE plots. Soil organic carbon, soil available nitrogen, available phosphorus contents did not differ with grazing exclusion treatments in both 0-15 and 15-30 cm layer. However, soil total nitrogen and total phosphorus contents were remarkably reduced due to grazing exclusion at the 0-15 cm depth. Furthermore, growing season temperature and/or growing season precipitation had significant effects on almost all soil properties and nutrients indicators. This study demonstrates that grazing exclusion had no impact on most soil properties and nutrients in Tibet. Additionally, the potential shift of climate conditions should be considered when recommend any policies designed for alpine grasslands degraded soil restoration in the future. Nevertheless, because the results of the present study come from short term (6-8 years) grazing exclusion, the assessments of the ecological effects of the grazing exclusion management strategy on soil quality of degraded alpine grasslands in Tibet still need long term continued research.

  2. Proximal gamma-ray spectroscopy to predict soil properties using windows and full-spectrum analysis methods.

    PubMed

    Mahmood, Hafiz Sultan; Hoogmoed, Willem B; van Henten, Eldert J

    2013-11-27

    Fine-scale spatial information on soil properties is needed to successfully implement precision agriculture. Proximal gamma-ray spectroscopy has recently emerged as a promising tool to collect fine-scale soil information. The objective of this study was to evaluate a proximal gamma-ray spectrometer to predict several soil properties using energy-windows and full-spectrum analysis methods in two differently managed sandy loam fields: conventional and organic. In the conventional field, both methods predicted clay, pH and total nitrogen with a good accuracy (R2 ≥ 0.56) in the top 0-15 cm soil depth, whereas in the organic field, only clay content was predicted with such accuracy. The highest prediction accuracy was found for total nitrogen (R2 = 0.75) in the conventional field in the energy-windows method. Predictions were better in the top 0-15 cm soil depths than in the 15-30 cm soil depths for individual and combined fields. This implies that gamma-ray spectroscopy can generally benefit soil characterisation for annual crops where the condition of the seedbed is important. Small differences in soil structure (conventional vs. organic) cannot be determined. As for the methodology, we conclude that the energy-windows method can establish relations between radionuclide data and soil properties as accurate as the full-spectrum analysis method.

  3. Soil respiration characteristics in different land uses and response of soil organic carbon to biochar addition in high-latitude agricultural area.

    PubMed

    Ouyang, Wei; Geng, Xiaojun; Huang, Wejia; Hao, Fanghua; Zhao, Jinbo

    2016-02-01

    The farmland tillage practices changed the soil chemical properties, which also impacted the soil respiration (R s ) process and the soil carbon conservation. Originally, the farmland in northeast China had high soil carbon content, which was decreased in the recent decades due to the tillage practices. To better understand the R s dynamics in different land use types and its relationship with soil carbon loss, soil samples at two layers (0-15 and 15-30 cm) were analyzed for organic carbon (OC), total nitrogen (TN), total phosphorus (TP), total carbon (TC), available nitrogen (AN), available phosphorus (AP), soil particle size distribution, as well as the R s rate. The R s rate of the paddy land was 0.22 (at 0-15 cm) and 3.01 (at 15-30 cm) times of the upland. The average concentrations of OC and clay content in cultivated areas were much lower than in non-cultivated areas. The partial least squares analysis suggested that the TC and TN were significantly related to the R s process in cultivated soils. The upland soil was further used to test soil CO2 emission response at different biochar addition levels during 70-days incubation. The measurement in the limited incubation period demonstrated that the addition of biochar improved the soil C content because it had high concentration of pyrogenic C, which was resistant to mineralization. The analysis showed that biochar addition can promote soil OC by mitigating carbon dioxide (CO2) emission. The biochar addition achieved the best performance for the soil carbon conservation in high-latitude agricultural area due to the originally high carbon content.

  4. 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

    2016-08-08

    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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    DOE PAGES

    Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.; ...

    2016-07-22

    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. In conclusion, the room temperature voltage-dependent 3-terminalmore » off-state drain current was adequately modeled with Frenkel-Poole emission.« less

  10. 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.

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

    DOE PAGES

    Beeler, R.; Roucka, R.; Chizmeshya, A. V. G.; ...

    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

  12. Scaling law and flux pinning in polycrystalline La1.85Sr0.15CuO4

    NASA Astrophysics Data System (ADS)

    Hampshire, D. P.; Ikeda, J. A. S.; Chiang, Y.-M.

    1989-11-01

    The transport critical current density (Jct) of two hot-pressed bulk polycrystalline La1.85Sr0.15CuO4 superconducting samples has been measured over the temperature range 2 K to Tc in magnetic fields up to 27 T. It is demonstrated that these data have a separable variable form Fp=JctB=α(D)B2.4c2 (T)b [where α(D) is a constant and b=B/Bc2(T)], in agreement with the Fietz-Webb scaling law. This is strong evidence that in high magnetic fields, flux pinning is the mechanism that determines the critical current density. The authors suggest that the dissipative state is described by flux flow along the regions of weak flux pinning at the grain boundaries.

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

    DOE PAGES

    Huang, S. X.; Chen, Fei; Kang, Jian; ...

    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.

  14. Magneto-structural correlations in Pr 0.15Gd 0.85Mn 2Ge 2

    NASA Astrophysics Data System (ADS)

    Dincer, I.; Elerman, Y.; Elmali, A.; Ehrenberg, H.; Fuess, H.; Baehtz, C.

    2006-11-01

    Magneto-structural correlations in Pr 0.15Gd 0.85Mn 2Ge 2 have been studied by synchrotron diffraction in the temperature range between 11 and 300 K. This compound crystallizes in the ThCr 2Si 2-type structure (space group I4/mmm). The unit cell parameters a and c were determined by Rietveld refinements as a function of temperature. Anomalies in the temperature dependence of the unit cell parameters a and c, the c/a ratio and the unit cell volume V at about 240 and 140 K, which is close to the magnetic phase transition temperatures, indicate a pronounced magneto-structural correlation. Spontaneous volume change and linear magnetostrictions are derived as a function of temperature.

  15. Growth and characterization of the La3Ga4.85Fe0.15SiO14 piezoelectric single crystal

    NASA Astrophysics Data System (ADS)

    Dou, Renqin; Liu, Wenpeng; Zhang, Qi; Zhang, Qingli; Ding, Shoujun; Shi, Zibin; Sun, Dunlu; Wang, Jiyang

    2017-01-01

    A new piezoelectric single crystal La3Ga4.85Fe0.15SiO14 (LGFS) was grown by the Czochralski method firstly. Its structural parameters were obtained by Rietveld refinement to the X-ray diffraction. The effective segregation coefficient k eff of Fe in the LGFS was determined to be 0.6. The cost of LGFS is reduced due to the doping of cheap Fe. The crystal density was measured to be 5.7 g cm-3 by the buoyancy method. The defect structure of LGFS crystal was investigated by the chemical etching with 85% H2SO4 etchant. Dislocation etching pit patterns of LGFS crystal are consistent with the corresponding atomic arrangement schematics. Compared with LGS, LGN, LGT, and LGAS crystal, the LGFS crystal exhibits outstanding dielectric and piezoelectric properties, and ɛ 11, ɛ 33, d 11, and d 14 are 20.86, 51.99, 6.5 pC/N, and -5.10 pC/N, respectively. Therefore, LGFS may be a new potential piezoelectric crystal with high performance and low expense.

  16. Huge Critical Current Density and Tailored Superconducting Anisotropy in SmFeAsO(0.8)F(0.15) by Low Density Columnar-Defect Incorporation

    NASA Astrophysics Data System (ADS)

    Welp, U.; Fang, L.; Jia, Y.; Mishra, V.; Chaparro, C.; Vlasko-Vlasov, V. K.; Koshelev, A. E.; Crabtree, G. W.; Zhu, S. F.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.; Kwok, W. K.

    2014-03-01

    SmFeAsO(0.8)F(0.15) is of great interest because it has the highest transition temperature of all the iron-based superconductors. We find that the introduction of a low density of correlated nano-scale defects enhances the critical current density up to 2 × 107A/cm2 at 5 K without any suppression in the high superconducting transition temperature of 50 K and amounting to 20 % of the theoretical depairing current density. We also observed a surprising reduction in the thermodynamic superconducting anisotropy from 8 to 4 upon irradiation. A model based on anisotropic electron scattering predicts that the superconducting anisotropy can be tailored via correlated defects in semi-metallic, fully gapped type II superconductors. - We acknowledge support by the Center for Emergent Superconductivity, an EFRC funded by the US DOE, Office of Basic Energy Sciences (LF, YJ, VM, AEK, WKK, GWC), by the DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 (CC, VKV, UW), by the EC Research Council project SuperIron (JK, SK), and by the Swiss National Science Foundation and the National Center of Competence in Research MaNEP (NDZ).

  17. 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].

  18. Wildfire effects on biological properties of soils in forest-steppe ecosystems of Russia

    NASA Astrophysics Data System (ADS)

    Maksimova, E.; Abakumov, E.

    2014-01-01

    Soils affected by forest wildfires in 2010 in Russia were studied on postfire and mature plots near the Togljatty city, Samara region. Soil biological properties and ash composition dynamics were investigated under the forest fire affect: a place of local forest fire, riding forest fire and unaffected site by fire-control (mature) during 3 yr of restoration. Soil samples were collected at 0-15 cm. Soil biological properties was measured by the fumigation method. The analytical data obtained shows that wildfires lead to serious changes in a soil profile and soil chemistry of upper horizons. Wildfires change a chemical composition of soil horizons and increase their ash-content. Fires lead to accumulation of biogenic elements' content (P and K) in the solum fine earth. Calcium content is increased as a result of fires that leads to an alkaline pH of the solum. The values of nutrients decreased as a result of leaching out with an atmospheric precipitation during the second year of restoration. Thus, when the upper horizons are burning the ash arriving on a soil surface enrich it with nutrients. The mature (unaffected by fire) soils is characterized by the greatest values of soil microbial biomass in the top horizon and, respectively, the bigger values of basal respiration whereas declining of the both parameters was revealed on postfire soils. Nevertheless this influence does not extend on depth more than 10 cm. Thus, fire affect on the soil were recognized in decreasing of microbiological activity.

  19. The Evolution of Star Formation Activity in Cluster Galaxies Over 0.15 < z < 1.5

    NASA Astrophysics Data System (ADS)

    Wagner, Cory R.

    In this thesis, we explore 7.5 billion years of evolution in cluster galaxy star formation activity using a sample of 11 high-redshift (1 < z < 1.5) clusters from the IRAC Shallow Cluster Survey, and 25 low-redshift (0.15 < z < 1) clusters from The Cluster Lensing And Supernova survey with Hubble. We compare cluster galaxy star formation to that of the field over 0.15 < z < 1.5 using 8000 galaxies from the UltraVISTA survey. Mid-infrared star formation rates are measured using Spitzer 24 mum data for isolated high-redshift galaxies. We calculate rest-frame ultraviolet star formation rates for low-redshift cluster members using Hubble Space Telescope observations. Using publically available mid-infrared and ultraviolet data for our field sample, we empirically derive scaling relations to adjust low-redshift cluster galaxy ultraviolet star formation rates to mid-infrared levels. We classify cluster galaxy morphology by visual inspection, and use quantitatively measured morphologies for field galaxies. Cluster late-type galaxies at z > 1 show enhanced star formation activity relative to the field, and account for nearly 90% of the overall star formation activity in high-redshift clusters. While high-redshift early-type galaxies are substantially quenched relative to cluster late-types, they still contribute 13% of the total cluster star formation activity. With early-type fractions increasing from 34 to 56% from z 1.5 → 1.16, we find that new cluster early-type galaxies are likely being formed around z 1.4. The fraction of early-type galaxies that are star-forming drops from 29 to 11% over this period, yet their specific star formation rates are roughly constant. These factors suggest that the events that created these new galaxies, possibly mergers, were both recent and gas-rich. With typical coverages of 50% of z < 1 cluster virial radii, we can only probe the cores of low-redshift clusters. We find that in this regime, the star formation activity of cluster

  20. 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.

  1. Electronic structure of (Ca{sub 0.85}La{sub 0.15})FeAs{sub 2}

    SciTech Connect

    Liu, Z.-H. Borisenko, S. V.; Kim, T. K.; Sala, A.; Ogino, H.; Shimoyama, J.; Büchner, B.

    2015-02-02

    We report a comprehensive study of orbital character and tridimensional nature of the electronic structure of (Ca{sub 0.85}La{sub 0.15})FeAs{sub 2} from recently discovered “112” family of Iron-based superconductors (IBS), with angle-resolved photoemission spectroscopy. We observed that the band structure is similar to that of “122” family, namely, there are three hole-like bands at the Brillouin zone (BZ) center and two electron-like bands at the BZ corner. The bands near the Fermi level (E{sub F}) are mainly derived from the Fe t{sub 2g} orbitals. On the basis of our present and earlier studies, we classify IBS into the three types according to their crystal structures. We show that although the bands near E{sub F} mainly originate from Fe 3d electrons, they are significantly modified by the interaction between the superconducting slabs and the intermediate atoms.

  2. [Effects of forest gap on seasonal dynamics of soil organic carbon and microbial biomass car- bon in Picea asperata forest in Miyaluo of Western Sichuan, Southwest China].

    PubMed

    Zhou, Yi-Gui; Hao, Kai-Jie; Li, Xian-Wei; Fan, Chuan; Chen, Yue-Lin; Liu, Yun-Ke; Wang, Xie

    2014-09-01

    Effects of gap sizes (50, 100 and 150 m2) on seasonal dynamics of soil organic carbon (SOC) and microbial biomass carbon (MBC) in soil surface (0-15 cm) and subsurface (15-30 cm) were investigated in a 50-year old Picea asperata plantation in Miyaluo forest, Western Si- chuan, China. In the four seasons, the SOC and MBC contents were higher in the soil surface than in soil subsurface in the four treatments, and varied insignificantly in different seasons. Compared with the control, the SOC content increased by 35.4%, 21.2% and 10.3% in soil surface, and by 45.5%, 25.0% and 12.1% in soil subsurface with the forest gaps of 50, 100 and 150 m2, respectively. The MBC content increased by 26.7%, 16.7%, 11.3% and 24.4%, 12.6%, 7.3% in soil surface and subsurface, respectively. There were significant negative relationship between soil SOC content and the soil pH and moisture, and significant positive relationship between soil SOC content and soil temperature. Significant effects of SOC content, soil pH, soil temperature, soil moisture on MBC content were observed, suggesting that forest gaps could significantly affect envi- ronmental conditions, and increasing gaps could reduce microbial activity and decomposition rate and decrease soil SOC and MBC contents.

  3. [Influence of double rice cropping system innovation on paddy soil profile form and soil characteristics].

    PubMed

    Zeng, Xi-Bai; Sun, Nan; Gao, Ju-Sheng; Li, Lian-Fang; Wang, Bo-Ren; Bai, Ling-Yu

    2008-05-01

    Field experiments were conducted on the double rice cropping paddy field in red soil area to evaluate the influence of cropping system innovation on soil profile form and related soil characteristics. Four cropping systems of rice-rice-Chinese Milkvetch (Astragalus sinicus Linn.), forage, paddy-upland rotation, and upland were substituted for the double rice cropping system. The results indicated that compared with those under double rice cropping system, the thickness of cultivated horizon under upland cropping system increased by 4 cm, that of plow pan declined by 2 cm, > 2 mm aggregates in wet-sieved particle-size fractions increased by 6.94%, wet-sieved mean-mass diameter increased by 0.37 mm, contents of humic acid carbon and fulvic acid carbon increased by 0.15 and 0.49 g kg(-1), respectively, and quotient of aggregates water stability was 0.78 times higher. Under paddy-upland rotation, the quotient of aggregates water stability was higher (95.86), while soil nutrient contents changed a little. Under rice-rice-Chinese Milkvetch system, soil organic matter content increased by 1.3 g kg(-1), quotient of aggregates water stability declined by 8.82, but other parameters had less changes. Under forage system, the thickness of cultivated and transitional horizons increased by 2 cm and 9 cm, respectively, quotient of aggregates water stability increased by 1.39, while the contents of soil organic matter and total potassium decreased by 5.6 and 2.8 g kg(-1), respectively. Among all test cropping systems, forage system had the greatest changes in soil characteristics. It was completely feasible to substitute the local double rice cropping system for paddy-upland rotation or upland cropping, particularly in the areas where full irrigation was not available. However, attention should be paid to the decrease of soil potassium content when the cropping system innovation was practiced.

  4. Metal and nanoparticle occurrence in biosolid-amended soils.

    PubMed

    Yang, Yu; Wang, Yifei; Westerhoff, Paul; Hristovski, Kiril; Jin, Virginia L; Johnson, Mari-Vaughn V; Arnold, Jeffrey G

    2014-07-01

    Metals can accumulate in soils amended with biosolids in which metals have been concentrated during wastewater treatment. The goal of this study is to inspect agricultural sites with long-term biosolid application for a suite of regulated and unregulated metals, including some potentially present as commonly used engineered nanomaterials (ENMs). Sampling occurred in fields at a municipal and a privately operated biosolid recycling facilities in Texas. Depth profiles of various metals were developed for control soils without biosolid amendment and soils with different rates of biosolid application (6.6 to 74 dry tons per hectare per year) over 5 to 25 years. Regulated metals of known toxicity, including chromium, copper, cadmium, lead, and zinc, had higher concentrations in the upper layer of biosolid-amended soils (top 0-30 cm or 0-15 cm) than in control soils. The depth profiles of unregulated metals (antimony, hafnium, molybdenum, niobium, gold, silver, tantalum, tin, tungsten, and zirconium) indicate higher concentrations in the 0-30 cm soil increment than in the 70-100 cm soil increment, indicating low vertical mobility after entering the soils. Titanium-containing particles between 50 nm and 250 nm in diameter were identified in soil by transmission electron microscopy (TEM) coupled with energy dispersive x-ray spectroscopy (EDX) analysis. In conjunction with other studies, this research shows the potential for nanomaterials used in society that enter the sewer system to be removed at municipal biological wastewater treatment plants and accumulate in agricultural fields. The metal concentrations observed herein could be used as representative exposure levels for eco-toxicological studies in these soils.

  5. A BCS-like gap in the superconductor SmFeAsO0.85F0.15.

    PubMed

    Chen, T Y; Tesanovic, Z; Liu, R H; Chen, X H; Chien, C L

    2008-06-26

    Since the discovery of superconductivity in the high-transition-temperature (high-T(c)) copper oxides two decades ago, it has been firmly established that the CuO(2) plane is essential for superconductivity and gives rise to a host of other very unusual properties. A new family of superconductors with the general composition of LaFeAsO(1-x)F(x) has recently been discovered and the conspicuous lack of the CuO(2) planes raises the tantalizing question of a different pairing mechanism in these oxypnictides. The superconducting gap (its magnitude, structure, and temperature dependence) is intimately related to pairing. Here we report the observation of a single gap in the superconductor SmFeAsO(0.85)F(0.15) with T(c) = 42 K as measured by Andreev spectroscopy. The gap value of 2Delta = 13.34 +/- 0.3 meV gives 2Delta/k(B)T(c) = 3.68 (where k(B) is the Boltzmann constant), close to the Bardeen-Cooper-Schrieffer (BCS) prediction of 3.53. The gap decreases with temperature and vanishes at T(c) in a manner consistent with the BCS prediction, but dramatically different from that of the pseudogap behaviour in the copper oxide superconductors. Our results clearly indicate a nodeless gap order parameter, which is nearly isotropic in size across different sections of the Fermi surface, and are not compatible with models involving antiferromagnetic fluctuations, strong correlations, the t-J model, and the like, originally designed for the high-T(c) copper oxides.

  6. Magnetization reversal behavior and magnetocaloric effect in SmCr0.85Mn0.15O3 chromites

    NASA Astrophysics Data System (ADS)

    Kumar, Surendra; Coondoo, Indrani; Vasundhara, M.; Patra, Ajit K.; Kholkin, Andrei L.; Panwar, Neeraj

    2017-01-01

    We have synthesized SmCr0.85Mn0.15O3 (SCMO) chromites through the ceramic route. The compound crystallized into a distorted orthorhombic structure with the Pnma space group, which was confirmed from the Rietveld refinement of x-ray powder diffraction patterns. Neel temperature, noticed at 168 K from the temperature variation of magnetisation, smaller than that reported for SmCrO3, indicated the influence of Mn3+ substitution on decreasing the antiferromagnetic ordering. A phenomenon of magnetization reversal was observed in the SCMO compound. At low magnetic fields, i.e., 500 Oe, a single compensation temperature (defined as the temperature where magnetization became zero) around 106 K was observed in the field cooled magnetization curve. However, with the application of higher magnetic fields, i.e., under an applied field of 1000 Oe, a second compensation temperature was noticed around 8 K. With a further increase in the magnetic field, the magnetization remained positive in both field cooled and zero field cooled protocols. A normal magnetocaloric effect was observed through an indirect method of field dependence of magnetisation measured in the temperature range of 2-152 K. The magnetic entropy change (-ΔS) of ˜11.36 J kg-1 K-1 along with the relative cooling power (RCP) of ˜175.89 J kg-1 was obtained in the temperature range of 10-20 K for an applied field of 90 kOe, and their values at 50 kOe applied field were, respectively, almost twenty and forty times larger in magnitude in comparison to those for the SmCrO3 compound. The relatively large values of ΔS and RCP make the studied compound a potential candidate for magnetic refrigeration applications at low temperatures.

  7. 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.

  8. Influence of tillage practices and straw incorporation on soil aggregates, organic carbon, and crop yields in a rice-wheat rotation system.

    PubMed

    Song, Ke; Yang, Jianjun; Xue, Yong; Lv, Weiguang; Zheng, Xianqing; Pan, Jianjun

    2016-11-04

    In this study, a fixed-site field experiment was conducted to study the influence of different combinations of tillage and straw incorporation management on carbon storage in different-sized soil aggregates and on crop yield after three years of rice-wheat rotation. Compared to conventional tillage, the percentages of >2 mm macroaggregates and water-stable macroaggregates in rice-wheat double-conservation tillage (zero-tillage and straw incorporation) were increased 17.22% and 36.38% in the 0-15cm soil layer and 28.93% and 66.34% in the 15-30 cm soil layer, respectively. Zero tillage and straw incorporation also increased the mean weight diameter and stability of the soil aggregates. In surface soil (0-15cm), the maximum proportion of total aggregated carbon was retained with 0.25-0.106 mm aggregates, and rice-wheat double-conservation tillage had the greatest ability to hold the organic carbon (33.64 g kg(-1)). However, different forms occurred at higher levels in the 15-30 cm soil layer under the conventional tillage. In terms of crop yield, the rice grown under conventional tillage and the wheat under zero tillage showed improved equivalent rice yields of 8.77% and 6.17% compared to rice-wheat double-cropping under zero tillage or conventional tillage, respectively.

  9. 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.

  10. Soil salinity study in Northern Great Plains sodium affected soil

    NASA Astrophysics Data System (ADS)

    Kharel, Tulsi P.

    Climate and land-use changes when combined with the marine sediments that underlay portions of the Northern Great Plains have increased the salinization and sodification risks. The objectives of this dissertation were to compare three chemical amendments (calcium chloride, sulfuric acid and gypsum) remediation strategies on water permeability and sodium (Na) transport in undisturbed soil columns and to develop a remote sensing technique to characterize salinization in South Dakota soils. Forty-eight undisturbed soil columns (30 cm x 15 cm) collected from White Lake, Redfield, and Pierpont were used to assess the chemical remediation strategies. In this study the experimental design was a completely randomized design and each treatment was replicated four times. Following the application of chemical remediation strategies, 45.2 cm of water was leached through these columns. The leachate was separated into 120- ml increments and analyzed for Na and electrical conductivity (EC). Sulfuric acid increased Na leaching, whereas gypsum and CaCl2 increased water permeability. Our results further indicate that to maintain effective water permeability, ratio between soil EC and sodium absorption ratio (SAR) should be considered. In the second study, soil samples from 0-15 cm depth in 62 x 62 m grid spacing were taken from the South Dakota Pierpont (65 ha) and Redfield (17 ha) sites. Saturated paste EC was measured on each soil sample. At each sampling points reflectance and derived indices (Landsat 5, 7, 8 images), elevation, slope and aspect (LiDAR) were extracted. Regression models based on multiple linear regression, classification and regression tree, cubist, and random forest techniques were developed and their ability to predict soil EC were compared. Results showed that: 1) Random forest method was found to be the most effective method because of its ability to capture spatially correlated variation, 2) the short wave infrared (1.5 -2.29 mum) and near infrared (0

  11. Residues of endosulfan in surface and subsurface agricultural soil and its bioremediation.

    PubMed

    Odukkathil, Greeshma; Vasudevan, Namasivayam

    2016-01-01

    The persistence of many hydrophobic pesticides has been reported by various workers in various soil environments and its bioremediation is a major concern due to less bioavailability. In the present study, the pesticide residues in the surface and subsurface soil in an area of intense agricultural activity in Pakkam Village of Thiruvallur District, Tamilnadu, India, and its bioremediation using a novel bacterial consortium was investigated. Surface (0-15 cm) and subsurface soils (15-30 cm and 30-40 cm) were sampled, and pesticides in different layers of the soil were analyzed. Alpha endosulfan and beta endosulfan concentrations ranged from 1.42 to 3.4 mg/g and 1.28-3.1 mg/g in the surface soil, 0.6-1.4 mg/g and 0.3-0.6 mg/g in the subsurface soil (15-30 cm), and 0.9-1.5 mg/g and 0.34-1.3 mg/g in the subsurface soil (30-40 cm) respectively. Residues of other persistent pesticides were also detected in minor concentrations. These soil layers were subjected to bioremediation using a novel bacterial consortium under a simulated soil profile condition in a soil reactor. The complete removal of alpha and beta endosulfan was observed over 25 days. Residues of endosulfate were also detected during bioremediation, which was subsequently degraded on the 30th day. This study revealed the existence of endosulfan in the surface and subsurface soils and also proved that the removal of such a ubiquitous pesticide in the surface and subsurface environment can be achieved in the field by bioaugumenting a biosurfactant-producing bacterial consortium that degrades pesticides.

  12. 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.

  13. CARBON SEQUESTRATION IN RECLAIMED MINED SOILS OF OHIO

    SciTech Connect

    M.K. Shukla; R. Lal

    2004-07-01

    This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites, owned and maintained by the American Electrical Power, are located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites, characterized by age chronosequences, were reclaimed with and without topsoil application and are under continuous grass or forest cover. During this quarter, bulk and core soil samples were collected from all 13 experimental sites for 0-15 cm, 15-30 cm, and 30-50 cm depths. In addition, 54 experimental plots (4 x 4 m) were established at three separate locations on reclaimed minesites to assess the influence of compost application on SOC during project period 2. This report presents the results from two sites reclaimed during 1978. The first site is under grass and the other under forest cover. The soil bulk density ({rho}{sub b}), SOC, total nitrogen (TN) concentrations and stocks were determined for these two sites on a 20 x 20 m grid. The preliminary analysis showed that the {rho}{sub b} ranged from 0.88 Mg m{sup -3} to 1.16 Mg m{sup -3} for 0-15 cm, 0.91 Mg m{sup -3} to 1.32 Mg m{sup -3} for 15-30 cm, and 1.37 Mg m{sup -3} to 1.93 Mg m{sup -3} for 30-50 cm depths in Cumberland tree site, and it's statistical variability was low. The variability in {rho}{sub b} was also low in Wilds grass site and ranged from 0.82 Mg m{sup -3} to 1.18 Mg m{sup -3} for 0-15 cm, 1.04 Mg m{sup -3} to 1.37 Mg m{sup -3} for 15-30 cm, and 1.18 Mg m{sup -3} to 1.83 Mg m{sup -3} for 30-50 cm depths. The {rho}{sub b} showed strong spatial dependence for 0-15 cm depth only in the Cumberland tree site. The SOC concentrations and stocks were highly variable with CV > 0.36 from all depths in both Wilds grass site and Cumberland tree site. The SOC stocks showed strong spatial dependence for 0-15 cm and 15-30 cm depths and moderate to strong for 20-50 cm depth in the Cumberland tree site. In contrast, in

  14. 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.

  15. A Randomized Multicenter Study Comparing 0.1%, 0.15%, and 0.3% Sodium Hyaluronate with 0.05% Cyclosporine in the Treatment of Dry Eye

    PubMed Central

    Park, Yuli; Song, Jong Suk; Choi, Chul Young; Yoon, Kyung Chul; Lee, Hyung Keun

    2017-01-01

    Abstract Purpose: To investigate the efficacy of 0.1%, 0.15%, and 0.3% sodium hyaluronate (SH) artificial tears compared with 0.05% cyclosporine (CS) ophthalmic solution for the treatment of dry eye. Methods: One hundred seventy-six patients were recruited and randomized to receive of 0.1%, 0.15%, and 0.3% SH and 0.05% CS. There was a primary end point which is the changes in the fluorescein corneal staining (FCS) score to determine noninferiority of 0.1%, 0.15%, and 0.3% SH. Secondary objective end points were lissamine green conjunctival staining (LGCS) scores, Schirmer test, and tear film break-up time (TBUT). Secondary subjective end point was ocular surface disease index (OSDI) score. These were evaluated before treatment and 6 and 12 weeks after start of treatment. Results: In the primary analysis, the mean change from baseline in FCS scores verified noninferiority of 0.1% and 0.15% SH to 0.05% CS and also indicated significant improvement of all groups (P < 0.05). Values for TBUT, LGCS scores, and OSDI scores showed significant improvements in all groups (P < 0.05), although no significant intergroup difference was shown. However, Schirmer test scores in the 0.15% SH group showed a significant tendency for better improvement at week 12 compared with the other groups (P < 0.05). No serious adverse events were observed. Conclusions: Administration of 0.1%, 0.15%, and 0.3% SH was effective in improving both the objective signs and subjective symptoms of dry eye. Those findings, in addition to the well-tolerated profile of 0.1%, 0.15%, and 0.3% SH, show that it is effective therapeutic method for dry eye. PMID:27929721

  16. Tracing copper derived from pig manure in calcareous soils and soil leachates by 65Cu labeling.

    PubMed

    Ostermann, Anne; He, Yao; Siemens, Jan; Welp, Gerhard; Heuser, Alexander; Wombacher, Frank; Münker, Carsten; Xue, Qiaoyun; Lin, Xianyong; Amelung, Wulf

    2015-04-07

    Copper is used as a growth promoter in animal husbandry, resulting in high Cu concentrations in animal manure. We tested whether Cu would be mobilized in soils receiving excessive loads of manure, both from recently added and from aged fractions. To discriminate between these Cu sources, manure was labeled with (65)Cu. After soil application of 0, 15, and 30 Mg manure ha(-1), leachate was collected in free-draining lysimeters (40 cm depth) under undisturbed soil over a 53 day period. Determining the total amounts of Cu and the fractions of (65)Cu in leachate and the soil profile enabled us to trace the translocation of Cu derived from labeled manure. More than 84% of the applied Cu was retained in the top 2 cm of soil. Less than 0.01% of the applied Cu was detected overall in the leachate. Of this amount, however, 38% (± 8.9 SE) was leached within 8 days after application. The total Cu concentration in leachates (32-164 μg L(-1)) frequently exceeded the Chinese groundwater quality standard of 50 μg L(-1). The added (65)Cu, however, accounted for less than 3.6% of the total Cu leaching load, suggesting that Cu from older sources and/or geological background controls contamination, regardless of current land management.

  17. Heavy metal content in soils under different wastewater irrigation patterns in Chihuahua, Mexico.

    PubMed

    Maldonado, V M; Arias, H O Rubio; Quintana, R; Saucedo, R A; Gutierrez, M; Ortega, J A; Nevarez, G V

    2008-12-01

    An area near the city of Chihuahua has been traditionally irrigated with wastewater to grow forage crops. It has been hypothesized that metal levels could be found in these soils high enough to cause potential health problems to the population. The objective of this study was to determine heavy metal concentrations in different soils due to irrigation practices. Four soil types were evaluated; a soil with a past and present history of wastewater irrigation (S1), a soil with a history of wastewater irrigation until 2003 (S2), a soil with no irrigation history (S3), and a soil similar to S1 and adjacent to the river where the wastewater is transported (S11). Three soil depths were evaluated; 0-15, 15-30 and 30-50 cm. Consequently, a total of 150 soil samples were analyzed evaluating pH, EC, OM and the following elements; Na, K, Cd, Pb, Ni, Cr, Cu and Fe. The pH (P=0.000) and EC (P=0.000) were different for each soil type but no differences were noted for soil depth and the interaction. Maximum pH levels were noted in S3 with a value of 8.74 while maximum EC was observed in S1 with a value of 0.850 dSm-1. The OM level was different for soil type (P=0.000), soil depth (P=0.005) and the interaction (P=0.014). S1 and S11 obtained maximum levels of OM while minimum levels were noted in S3. Maximum OM levels were observed at the 0-15 cm depth followed by the 15-30 cm depth and finally at the 30-50 cm depth. The highest concentration of metals was as follows: K in S1 (359.3 mg kg-1); Cd in S1 (4.48 mg kg-1); Pb in S11 (155.83 mg kg-1); Ni in S1 (10.74 mg kg-1); Cu in S1 (51.36 mg kg-1); B in S3 (41.5 mg kg-1); Fe in S3 (20,313.0 mg kg-1), Cr in S3 (44.26 mg kg-1) and Na in S3 (203.0 mg kg-1). The conclusion is that some metals are present in the soils due to anthropogenic activities but others are present in natural forms.

  18. Rock fragments induce patchy distribution of soil water repellency in burned soils

    NASA Astrophysics Data System (ADS)

    Gordillo-Rivero, Ángel; García-Moreno, Jorge; Bárcenas-Moreno, Gema; Jiménez-Morillo, Nicasio T.; Mataix-Solera, Jorge; Jordán, Antonio; Zavala, Lorena M.

    2013-04-01

    Forest fires are recurrent phenomena in the Mediterranean area and are one of the main causes of changes in the Mediterranean ecosystems, increasing the risk of soil erosion and desertification. Fire is an important agent which can induce important changes in the chemical and physical characteristics of soils. During wildfires, only a small part of the heat generated is transmitted to the first centimetres of the soil profile. The intensity of the changes produced in the physical and chemical characteristics of the soil depends on the temperatures reached at different soil depths, the time of residence of temperature peaks, and the stability of the different soil components. One of the soil physical properties strongly affected by fire is soil water repellency (WR). Depending on temperature, time of heating, type of soil and fuel, fire can induce, enhance or destroy soil WR. Soil WR is a key factor in controlling soil hydrology and water availability in burnt soils together with other factors as texture or aggregation. Although the occurrence and consequences of fire-induced soil WR have been deeply studied, some gaps still exist, as the influence of rock fragment cover during burning. During combustion of litter and aerial biomass, the soil surface under rock fragments is heated and reachs temperature peaks after a certain delay respect to exposed areas. In contrast, temperature peaks are longer, increasing the time of residence of high temperature. In consequence, rock fragments may change the expected spatial distribution of soil WR. Up to date, very scarce research concerns the effect of rock fragments at the soil surface on the fire-induced pattern of soil water repellency. METHODS Two experiments were carried out in this research. In the first case, an experiment was conducted in an experimental farm in Sevilla (southern Spain). The effect of a low severity prescribed fire was studied in soil plots under different rock fragment covers (0, 15, 30, 45 and 60

  19. 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.

  20. Colonization and community structure of root-associated microorganisms of Sabina vulgaris with soil depth in a semiarid desert ecosystem with shallow groundwater.

    PubMed

    Taniguchi, Takeshi; Usuki, Hiroyuki; Kikuchi, Junichi; Hirobe, Muneto; Miki, Naoko; Fukuda, Kenji; Zhang, Guosheng; Wang, Linhe; Yoshikawa, Ken; Yamanaka, Norikazu

    2012-08-01

    Arbuscular mycorrhizal fungi (AMF) have been observed in deep soil layers in arid lands. However, change in AMF community structure with soil depth and vertical distributions of the other root-associated microorganisms are unclear. Here, we examined colonization by AMF and dark septate fungi (DSF), as well as the community structure of AMF and endophytic fungi (EF) and endophytic bacteria (EB) in association with soil depth in a semiarid desert with shallow groundwater. Roots of Sabina vulgaris and soils were collected from surface to groundwater level at 20-cm intervals. Soil chemistry (water content, total N, and available P) and colonization of AMF and DSF were measured. Community structures of AMF, EF, and EB were examined by terminal restriction fragment length polymorphism analysis. AMF colonization decreased with soil depth, although it was mostly higher than 50%. Number of AMF phylotypes decreased with soil depth, but more than five phylotypes were observed at depths up to 100 cm. Number of AMF phylotypes had a significant and positive relationship with soil moisture level within 0-15% of soil water content. DSF colonization was high but limited to soil surface. Number of phylotypes of EF and EB were diverse even in deep soil layers, and the community composition was associated with the colonization and community composition of AMF. This study indicates that AMF species richness in roots decreases but is maintained in deep soil layers in semiarid regions, and change in AMF colonization and community structure associates with community structure of the other root-associated microorganisms.

  1. Displacement waves in La2CuO(4-delta) and La(1.85)Sr(0.15)CuO(4-delta)

    NASA Astrophysics Data System (ADS)

    Kajitani, Tsuyoshi; Onozuka, Takashi; Yamaguchi, Yasuo; Hirabayashi, Makoto; Syono, Yasuhiko

    1987-11-01

    Structural investigation of orthorhombic La2CuO(4-delta) and La(1.85)Sr(0.15)CuO(4-delta) was carried out by means of X-ray and neutron diffraction on the basis of the space group Cmmm. The periodic expansion/contraction type distortion of CuO6 octahedra was found in both orthorhombic compounds. The distortion is nearly one-dimensional in La2CuO(4-delta) but is two-dimensional in La(1.85)Sr(0.15)CuO(4-delta). The existence of a charge-density wave is highly possible in the structures.

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

    DOE PAGES

    Meyer, Tricia L; Jiang, Lu; Park, Sungkyun; ...

    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. The nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their amorphous thin films

    NASA Astrophysics Data System (ADS)

    Karatay, Ahmet; Aksoy, Çagla; Gul Yaglioglu, H.; Elmali, Ayhan; Kürüm, Ulaş; Ateş, Aytunç; Gasanly, Nizami

    2011-07-01

    We investigated the nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their very thin amorphous films by open aperture (OA) Z-scan and pump-probe techniques. The linear absorption spectra indicated a blue shift in energy with increasing film thickness. This can be attributed to the quantum confinement effect. For both 4 ns and 65 ps pulse durations the two photon absorption coefficients of Ga0.90In0.10Se and Ga0.85In0.15Se crystals increased with increasing input intensities. The life time of the localized defect states was measured as 3 ns for both Ga0.90In0.10Se and Ga0.85In0.15Se films while it was around 10 ns for GaSe and InSe films. Open aperture Z-scan experiments with a 4 ns pulse duration did not exhibit any saturable absorption behavior for thin films since the life time of localized defect states was not long enough to saturate these films. Thinner films exhibited saturable absorption and thicker films exhibited nonlinear absorption for a 65 ps pulse duration. This behavior was attributed to increasing localized defect states with increasing film thickness. The experimental curves were fitted to the theory of the open aperture Gaussian-beam Z-scan based on the Adomian decomposition method incorporating one photon, two photon, and free carrier absorptions and their saturations. The lowest saturation intensity threshold for the Ga0.90In0.10Se film was found to be 1.38 × 102 MW cm - 2 for 43 nm film thickness.

  4. 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.

  5. Long-term effects of fertilizer on soil enzymatic activity of wheat field soil in Loess Plateau, China.

    PubMed

    Hu, Weigang; Jiao, Zhifang; Wu, Fasi; Liu, Yongjun; Dong, Maoxing; Ma, Xiaojun; Fan, Tinglu; An, Lizhe; Feng, Huyuan

    2014-12-01

    The effects of long-term (29 years) fertilization on local agro-ecosystems in the Loess Plateau of northwest China, containing a single or combinations of inorganic (Nitrogen, N; Phosphate, P) and organic (Mature, M Straw, S) fertilizer, including N, NP, SNP, M, MNP, and a control. The soil enzymes, including dehydrogenase, urease, alkaline phosphatase, invertase and glomalin, were investigated in three physiological stages (Jointing, Dough, and Maturity) of wheat growth at three depths of the soil profile (0-15, 16-30, 31-45 cm). We found that the application of farmyard manure and straw produced the highest values of soil enzymatic activity, especially a balanced applied treatment of MNP. Enzymatic activity was lowest in the control. Values were generally highest at dough, followed by the jointing and maturity stages, and declined with soil profile depth. The activities of the enzymes investigated here are significantly correlated with each other and are correlated with soil nutrients, in particular with soil organic carbon. Our results suggest that a balanced application of fertilizer nutrients and organic manure (especially those containing P) has positive effects on multiple soil chemical parameters, which in turn enhances enzyme activity. We emphasize the role of organic manure in maintaining soil organic matter and promoting biological activity, as its application can result in a substantial increase in agricultural production and can be sustainable for many years.

  6. [Dynamic changes of surface soil organic carbon and light-fraction organic carbon after mobile dune afforestation with Mongolian pine in Horqin Sandy Land].

    PubMed

    Shang, Wen; Li, Yu-qiang; Wang, Shao-kun; Feng, Jing; Su, Na

    2011-08-01

    This paper studied the dynamic changes of surface (0-15 cm) soil organic carbon (SOC) and light-fraction organic carbon (LFOC) in 25- and 35-year-old sand-fixing Mongolian pine (Pinus sylvestris var. mongolica) plantations in Horqin Sandy Land, with a mobile dune as a comparison site. After the afforestation on mobile dune, the content of coarse sand in soil decreased, while that of fine sand and clay-silt increased significantly. The SOC and LFOC contents also increased significantly, but tended to decrease with increasing soil depth. Afforestation increased the storages of SOC and LFOC in surface soil, and the increment increased with plantation age. In the two plantations, the increment of surface soil LFOC storage was much higher than that of SOC storage, suggesting that mobile dune afforestation had a larger effect on surface soil LFOC than on SOC.

  7. Energy-storage properties and electrocaloric effect of Pb(1-3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films.

    PubMed

    Zhao, Ye; Hao, Xihong; Zhang, Qi

    2014-07-23

    Antiferroelectric (AFE) thick (1 μm) films of Pb(1-3x/2)LaxZr0.85Ti0.15O3 (PLZT) with x = 0.08, 0.10, 0.12, and 0.14 were deposited on LaNiO3/Si (100) substrates by a sol-gel method. The dielectric properties, energy-storage performance, electrocaloric effect, and leakage current behavior were investigated in detail. With increasing La content, dielectric constant and saturated polarizations of the thick films were gradually decreased. A maximum recoverable energy-storage density of 38 J/cm(3) and efficiency of 71% were achieved in the thick films with x = 0.12 at room temperature. A large reversible adiabatic temperature change of ΔT = 25.0 °C was presented in the thick films with x = 0.08 at 127 °C at 990 kV/cm. Moreover, all the samples had a lower leakage current density below 10(-6) A/cm(2) at room temperature. These results indicated that the PLZT AFE thick films could be a potential candidate for applications in high energy-storage density capacitors and cooling devices.

  8. Huge critical current density and tailored superconducting anisotropy in SmFeAsO0.8F0.15 by low-density columnar-defect incorporation

    NASA Astrophysics Data System (ADS)

    Fang, L.; Jia, Y.; Mishra, V.; Chaparro, C.; Vlasko-Vlasov, V. K.; Koshelev, A. E.; Welp, U.; Crabtree, G. W.; Zhu, S.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.; Kwok, W. K.

    2013-11-01

    Iron-based superconductors could be useful for electricity distribution and superconducting magnet applications because of their relatively high critical current densities and upper critical fields. SmFeAsO0.8F0.15 is of particular interest as it has the highest transition temperature among these materials. Here we show that by introducing a low density of correlated nano-scale defects into this material by heavy-ion irradiation, we can increase its critical current density to up to 2 × 107 A cm-2 at 5 K—the highest ever reported for an iron-based superconductor—without reducing its critical temperature of 50 K. We also observe a notable reduction in the thermodynamic superconducting anisotropy, from 8 to 4 upon irradiation. We develop a model based on anisotropic electron scattering that predicts that the superconducting anisotropy can be tailored via correlated defects in semimetallic, fully gapped type II superconductors.

  9. Multiferroic and magnetoelectric properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 core-shell nanocomposite

    NASA Astrophysics Data System (ADS)

    Kumar, Ajith S.; Lekha, C. S. Chitra; Vivek, S.; Saravanan, Venkata; Nandakumar, K.; Nair, Swapna S.

    2016-11-01

    Lead-free magnetoelectric (ME) composites with remarkable ME coupling are required for the realization of eco-friendly multifunctional devices. This work demonstrates the ME properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 (BCZT-CFO) core-shell composites synthesized via co-sol-gel technique. Room temperature ferroelectric and ferromagnetic characterization have shown that the samples are magnetic and ferroelectric along with an adequate magnetoelectric coupling of 12.15 mV/(cm Oe). The strong dependence of electric parameters on applied magnetic DC bias fields demonstrated in ferroelectric and magnetoelectric measurements provide a framework for the development of potential magnetoelectric devices. Also, the high sensitivity of magnetoelectric coupling towards the applied AC magnetic field can be used for its application in magnetoelectric sensors.

  10. Effects of land use changes on the dynamics of selected soil properties in northeast Wellega, Ethiopia

    NASA Astrophysics Data System (ADS)

    Adugna, Alemayehu; Abegaz, Assefa

    2016-02-01

    Land use change can have negative or positive effects on soil quality. Our objective was to assess the effects of land uses changes on the dynamics of selected soil physical and chemical properties. Soil samples were collected from three adjacent soil plots under different land uses, namely forestland, grazing land, and cultivated land at 0-15 cm depth. Changes in soil properties on cultivated and grazing land were computed and compared to forestland, and ANOVA (analysis of variance) was used to test the significance of the changes. Sand and silt proportions, soil organic content, total nitrogen content, acidity, cation exchange capacity, and exchangeable Ca2+ content were higher in forestlands. Exchangeable Mg2+ was highest in grazing land, while clay, available phosphorous, and exchangeable K+ were highest in cultivated land. The percentage changes in sand, clay, soil organic matter, cation exchange capacity, and exchangeable Ca2+ and Mg2+ were higher in cultivated land than in grazing land and forestland. In terms of the relation between soil properties, soil organic matter, total nitrogen, cation exchange capacity, and exchangeable Ca2+ were strongly positively correlated with most of soil properties, while available phosphorous and silt have no significant relationship with any of the other considered soil properties. Clay has a negative correlation with all soil properties. Generally, cultivated land has the least concentration of soil physical and chemical properties except clay and available phosphorous, which suggests an increasing degradation rate in soils of cultivated land. So as to increase soil organic matter and other nutrients in the soil of cultivated land, the integrated implementation of land management through compost, cover crops, manures, minimum tillage, crop rotation, and liming to decrease soil acidity are suggested.

  11. [Effects of Chinese prickly ash orchard on soil organic carbon mineralization and labile organic carbon in karst rocky desertification region of Guizhou province].

    PubMed

    Zhang, Wen-Juan; Liao, Hong-Kai; Long, Jian; Li, Juan; Liu, Ling-Fei

    2015-03-01

    Taking 5-year-old Chinese prickly ash orchard (PO-5), 17-year-old Chinese prickly ash orchard (PO- 17), 30-year-old Chinese prickly ash orchard (PO-30) and the forest land (FL, about 60 years) in typical demonstration area of desertification control test in southwestern Guizhou as our research objects, the aim of this study using a batch incubation experiment was to research the mineralization characteristics of soil organic carbon and changes of the labile soil organic carbon contents at different depths (0-15 cm, 15-30 cm, and 30-50 cm). The results showed that: the cumulative mineralization amounts of soil organic carbon were in the order of 30-year-old Chinese prickly ash orchard, the forest land, 5-year-old Chinese prickly ash orchard and 17-year-old Chinese prickly ash orchard at corresponding depth. Distribution ratios of CO2-C cumulative mineralization amount to SOC contents were higher in Chinese prickly ash orchards than in forest land at each depth. Cultivation of Chinese prickly ash in long-term enhanced the mineralization of soil organic carbon, and decreased the stability of soil organic carbon. Readily oxidized carbon and particulate organic carbon in forest land soils were significantly more than those in Chinese prickly ash orchards at each depth (P < 0.05). With the increasing times of cultivation of Chinese prickly ash, the contents of readily oxidized carbon and particulate organic carbon first increased and then declined at 0-15 cm and 15-30 cm depth, respectively, but an opposite trend was found at 30-50 cm depth. At 0-15 cm and 15-30 cm, cultivation of Chinese prickly ash could be good for improving the contents of labile soil organic carbon in short term, but it was not conducive in long-term. In this study, we found that cultivation of Chinese prickly ash was beneficial for the accumulation of labile organic carbon at the 30-50 cm depth.

  12. Effects of Agaricus lilaceps fairy rings on soil aggregation and microbial community structure in relation to growth stimulation of western wheatgrass (Pascopyrum smithii) in Eastern Montana rangeland.

    PubMed

    Caesar-Tonthat, The Can; Espeland, Erin; Caesar, Anthony J; Sainju, Upendra M; Lartey, Robert T; Gaskin, John F

    2013-07-01

    Stimulation of plant productivity caused by Agaricus fairy rings has been reported, but little is known about the effects of these fungi on soil aggregation and the microbial community structure, particularly the communities that can bind soil particles. We studied three concentric zones of Agaricus lilaceps fairy rings in Eastern Montana that stimulate western wheatgrass (Pascopyrum smithii): outside the ring (OUT), inside the ring (IN), and stimulated zone adjacent to the fungal fruiting bodies (SZ) to determine (1) soil aggregate proportion and stability, (2) the microbial community composition and the N-acetyl-β-D-glucosaminidase activity associated with bulk soil at 0-15 cm depth, (3) the predominant culturable bacterial communities that can bind to soil adhering to wheatgrass roots, and (4) the stimulation of wheatgrass production. In bulk soil, macroaggregates (4.75-2.00 and 2.00-0.25 mm) and aggregate stability increased in SZ compared to IN and OUT. The high ratio of fungal to bacteria (fatty acid methyl ester) and N-acetyl-β-D-glucosaminidase activity in SZ compared to IN and OUT suggest high fungal biomass. A soil sedimentation assay performed on the predominant isolates from root-adhering soil indicated more soil-binding bacteria in SZ than IN and OUT; Pseudomonas fluorescens and Stenotrophomonas maltophilia isolates predominated in SZ, whereas Bacillus spp. isolates predominated in IN and OUT. This study suggests that growth stimulation of wheatgrass in A. lilaceps fairy rings may be attributed to the activity of the fungus by enhancing soil aggregation of bulk soil at 0-15 cm depth and influencing the amount and functionality of specific predominant microbial communities in the wheatgrass root-adhering soil.

  13. Regional scale assessment of soil predictors of groundwater phosphate (P) levels in acidic sandy agricultural soils

    NASA Astrophysics Data System (ADS)

    Mabilde, Lisa

    2016-04-01

    Possible factors affecting the leaching of P to the groundwater in the Belgian sandy area are examined via regression analysis. The main objective is to investigate the dependency of phreatic groundwater phosphate concentrations (Flemish VMM monitoring net, monitoring period 2010-2013) on soil phosphate saturation degree (PSD) (1994-1997 mapping for Flemish Land Agency) (n = 1032). Additionally explored parameters include: depth distributions of Fe- and Al-oxides, sorbed P and phosphate sorption capacity (PSC) and soil pH. Interpolated data of these soil parameters in 3 depth layers (0-30, 30-60, 60-90 cm) were generated by ordinary kriging. Secondly, we assessed the significance of other edaphic factors potentially controlling the groundwater P: topsoil organic carbon content (OC %), soil clay content and fluctuation of the groundwater table. Overall, the mean PSD halved with each 30 cm depth layer (56 > 24 > 13 %) and was correlated to groundwater PO43- level. The statistical significance of the correlation with groundwater PO43- concentrations increased with depth layer. The poor correlation (R2 = 0.01) between PSD and groundwater phosphate concentration indicates that many factors, other than soil P status, control the transport of P from soil solution to the groundwater in Belgian sandy soils. A significant (P<0.01) positive non-linear relationship was found between groundwater PO43-concentration and pHKCl in all three studied depth layers, again increasingly with depth. Within the pH range of the 30-60 cm layer (pHKCl 4.0-5.7) PO4- solubility should increase with pH. Elevated soil OC levels surprisingly co-occurred with low groundwater PO43- concentrations (r = -0.18, P<0.01, n = 191). Groundwater PO43- was furthermore significantly and positively correlated to clay % in both the 0-15 cm (r = 0.15, τ = 0.25, P<0.01, n = 1032) and 60-90 cm (r = 0.13, τ = 0.20, P<0.01, n = 1032) depth increments. These positive correlations were unexpected and could be

  14. Evaluation of soil moisture sensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the measurement accuracy and repeatability of the EC-5 and 5TM soil volumetric water content (SVWC) sensors, MPS-2 and 200SS soil water potential (SWP) sensors, and 200TS soil temperature sensor. Six 183cm x 183cm x 71cm wooden compartments were built inside a greenhouse, and e...

  15. Topsoil and Deep Soil Organic Carbon Concentration and Stability Vary with Aggregate Size and Vegetation Type in Subtropical China.

    PubMed

    Fang, Xiang-Min; Chen, Fu-Sheng; Wan, Song-Ze; Yang, Qing-Pei; Shi, Jian-Min

    2015-01-01

    The impact of reforestation on soil organic carbon (OC), especially in deep layer, is poorly understood and deep soil OC stabilization in relation with aggregation and vegetation type in afforested area is unknown. Here, we collected topsoil (0-15 cm) and deep soil (30-45 cm) from six paired coniferous forests (CF) and broad-leaved forests (BF) reforested in the early 1990s in subtropical China. Soil aggregates were separated by size by dry sieving and OC stability was measured by closed-jar alkali-absorption in 71 incubation days. Soil OC concentration and mean weight diameter were higher in BF than CF. The cumulative carbon mineralization (Cmin, mg CO2-C kg-1 soil) varied with aggregate size in BF and CF topsoils, and in deep soil, it was higher in larger aggregates than in smaller aggregates in BF, but not CF. The percentage of soil OC mineralized (SOCmin, % SOC) was in general higher in larger aggregates than in smaller aggregates. Meanwhile, SOCmin was greater in CF than in BF at topsoil and deep soil aggregates. In comparison to topsoil, deep soil aggregates generally exhibited a lower Cmin, and higher SOCmin. Total nitrogen (N) and the ratio of carbon to phosphorus (C/P) were generally higher in BF than in CF in topsoil and deep soil aggregates, while the same trend of N/P was only found in deep soil aggregates. Moreover, the SOCmin negatively correlated with OC, total N, C/P and N/P. This work suggests that reforested vegetation type might play an important role in soil OC storage through internal nutrient cycling. Soil depth and aggregate size influenced OC stability, and deep soil OC stability could be altered by vegetation reforested about 20 years.

  16. Saturation of resistivity and Kohler's rule in Ni-doped La1.85Sr0.15CuO4 cuprate

    NASA Astrophysics Data System (ADS)

    Malinowski, A.; Bezusyy, V. L.; Nowicki, P.

    2017-01-01

    We present the results of electrical transport measurements of La1.85Sr0.15Cu1 -yNiyO4 thin single-crystal films at magnetic fields up to 9 T. Adding Ni impurity with strong Coulomb scattering potential to a slightly underdoped cuprate makes the signs of resistivity saturation at ρsat visible in the measurement temperature window up to 350 K. Employing the parallel-resistor formalism reveals that ρsat is consistent with the classical Ioffe-Regel-Mott limit and changes with carrier concentration n as ρsat∝1 /√{n } . Thermopower measurements show that Ni tends to localize mobile carriers, decreasing their effective concentration as n ≅0.15 -y . The classical unmodified Kohler's rule is fulfilled for magnetoresistance in the nonsuperconducting part of the phase diagram when applied to the ideal branch in the parallel-resistor model.

  17. 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.

  18. Synthesis method, control of cationic composition and superconducting behavior of Nd 1.85Ce 0.15Cu 1±δO y

    NASA Astrophysics Data System (ADS)

    Serquis, A.; Prado, F.; Caneiro, A.

    1995-02-01

    Samples of Nd 1.85Ce 0.15Cu 1 ± °O y (0.99 ⩽ ± δ ⩽ 1.02) were prepared by a solid-state reaction (SSR), nitrate-decomposition method (NDM) and liquid-mix method (LMM) and characterized by XRD, SEM, EPMA, DTA and DC magnetization. The control of Cu content, substitutional impurities and Ce homogeneity depends on the synthesis method, which modifies the microstructure and the superconducting behavior of these materials. Our results show that in Nd 1.85Ce 0.15Cu 1 ± δO y small variations of δ strongly affect the superconducting properties. For 1 + δ > 1.00 the Meissner fraction and the superconducting transition are substantially improved.

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

    DOE PAGES

    Dias, Yasmin; Wang, Hui; Zhou, Haiqing; ...

    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

  20. Magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys prepared by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Gómez, J. A.; Xia, S. K.; Passamani, E. C.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    2001-01-01

    The magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys have been studied by Mössbauer spectroscopy, magnetization and resistivity measurements. The samples were prepared by mechanical alloying of Fe and Ag powders in a high-energy ball mill. Mössbauer spectroscopy and magnetic measurements of the final milled samples indicate the presence of single-domain 'Fe' particles. The magnetoresistance values, at 4.2 K and for a magnetic field of 8 T, are 2.5% and 5.7% for samples Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30, respectively. The magnetoresistance behavior indicates the cluster-glass-like features in both the final milled samples.

  1. 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.

  2. 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.

  3. 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.

  4. A robust high performance cobalt-free oxygen electrode La0.5Sr0.5Fe0.8Cu0.15Nb0.05O3-δ for reversible solid oxide electrochemical cell

    NASA Astrophysics Data System (ADS)

    Zhou, Ning; Yin, Yi-Mei; Li, Jingcheng; Xu, Lei; Ma, Zi-Feng

    2017-02-01

    A novel cobalt-free perovskite oxide La0.5Sr0.5Fe0.8Cu0.15Nb0.05O3-δ (LSFCN) has been synthesized and evaluated as oxygen electrode for reversible solid oxide electrochemical cells (RSOCs). The performance and stability of the LSFCN based RSOCs have been characterized in fuel cell and electrolysis modes, and the reversibility of the cells has been proven. In FC mode, the cell exhibits the maximum power density of 1.10 Wcm-2 at 800 °C, and a stable output under 0.7 V at 700 °C during 108 h. The performance and stability of the cell in electrolysis mode are also remarkable. An electrolysis current of 0.85 A cm-2 is achieved at 750 °C with an applied voltage of 1.3 V, and no degradation as well as delamination are observed for the cell after 50 h electrolysis under voltage of 1.60 V (∼1.27 A cm-2) at 800 °C. The high performance of the LSFCN at both cathodic and anodic conditions may be attributed to the inherent high electrochemical activity of copper-iron based perovskites; and the incorporation of Nb5+ cations into perovskite lattice is responsible for the stability of LSFCN, which leads to the more stable crystal structure, lower thermal expansion coefficient and the reduced Sr segregation at surface.

  5. Determination of the 243 Cm/244 Cm ratio alpha spectrometry and spectral deconvolution in environmental samples exposed to discharges from the nuclear fuel cycle.

    PubMed

    Mitchell, P I; Holm, E; León Vintró, L; Condren, O M; Roos, P

    1998-01-01

    The presence of curium nuclides in irradiated nuclear fuel is well known, as is their occurrence in environmental materials exposed to liquid waste discharges from reprocessing plants and to fallout following the Chernobyl accident. Knowledge of the 242 Cm/244 Cm and 243 Cm/244 Cm atom ratios can be a useful tool for characterizing a source-term and assessing the burn-up history of nuclear fuel. Here, a practical technique, based on high-resolution alpha spectrometry and spectral deconvolution, is described by which the 243, 244 Cm multiplet can be resolved at the low activities typical of most environmental samples. The resulting 243 Cm/244 Cm ratio is then used to correct for any interference by 243 Cm in the 242 Cm window. The technique has been applied to the determination of the 243 Cm/244 Cm ratio in samples of seabed sediment collected near the Sellafield outfall, riverine sediment sampled downstream of the Mayak reprocessing plant and soil and lichen from within the Chernobyl exclusion zone. Near Sellafield, the 243 Cm/244 Cm ratio was found to be < 2%, while near Mayak and Chernobyl it was considerably higher, being approximately 6-8%.

  6. Trace element analysis of soil type collected from the Manjung and central Perak

    SciTech Connect

    Azman, Muhammad Azfar Hamzah, Suhaimi; Rahman, Shamsiah Abdul; Elias, Md Suhaimi; Abdullah, Nazaratul Ashifa; Hashim, Azian; Shukor, Shakirah Abd; Kamaruddin, Ahmad Hasnulhadi Che

    2015-04-29

    Trace elements in soils primarily originated from their parent materials. Parents’ material is the underlying geological material that has been undergone different types of chemical weathering and leaching processes. Soil trace elements concentrations may be increases as a result of continuous input from various human activities, including power generation, agriculture, mining and manufacturing. This paper describes the Neutron Activation Analysis (NAA) method used for the determination of trace elements concentrations in part per million (ppm) present in the terrestrial environment soil in Perak. The data may indicate any contamination of trace elements contributed from human activities in the area. The enrichment factors were used to check if there any contamination due to the human activities (power plants, agricultural, mining, etc.) otherwise the values would serve as a baseline data for future study. The samples were collected from 27 locations of different soil series in the area at two different depths: the top soil (0-15cm) and the sub soil (15-30cm). The collected soil samples were air dried at 60°C and passed through 2 µm sieve. Instrumental Neutron Activation Analysis (NAA) has been used for the determination of trace elements. Samples were activated in the Nuclear Malaysia TRIGA Mark II reactor followed by gamma spectrometric analysis. By activating the stable elements in the samples, the elements can be determined from the intensities of gamma energies emitted by the respected radionuclides.

  7. Structural, magnetic and magnetoelectric properties of single phase La3+ and Er3+ co-doped Bi0.85-x La0.15Er x FeO3 (0 ≤ x ≤ 0.1) ceramics

    NASA Astrophysics Data System (ADS)

    Manjusha; Yadav, K. L.; Mall, Ashish Kumar

    2016-11-01

    A sol-gel reaction method is used to prepare La3+ and Er3+ co-doped ceramic Bi0.85-x La0.15Er x FeO3 (x = 0, 0.05, 0.07 and 0.10) equivalently denoted as BLEFO. Bi0.85-x La0.15Er x FeO3 exhibits the structural transition from rhombohedral to a triclinic structure with quite small triclinic distortion; as confirmed by the Rietveld refinement analysis. Field emission scanning electron micrographs reveal the presence of interconnected spherical grains. From transmission electron microscopy, the average crystal size was found to be 60-65 nm. Co-doping with La and Er enhanced the magnetic properties such as saturation magnetization and magnetic moment of BiFeO3 as confirmed by vibrating sample magnetometer at 300 K and as well as by superconducting quantum interference device (SQUID) analysis at 5 K. An unusual behavior has been observed in BLEFO at 300 K, because it shows the weak ferromagnetic behavior besides its antiferromagnetic nature at room temperature. An irreversibility effect and a large bifurcation have been observed below room temperature in BLEFO in SQUID measurement. The value of magnetoelectric (ME) coupling coefficient increases from 2.60 (x = 0) to 6.58 (x = 0.10) mV cm-1-Oe at 3500 Oe. A negative temperature coefficient of the resistance behavior analogous to a semiconductor is confirmed by the impedance analysis. The enhanced multiferroic properties are attributed to the enhanced ME interaction, which results from the La and Er substitution at A site of BiFeO3.

  8. Diel variation in the vertical distribution of particulate matter (>0.15 mm) in the NW Mediterranean Sea investigated with the Underwater Video Profiler

    NASA Astrophysics Data System (ADS)

    Stemmann, Lars; Picheral, Marc; Gorsky, Gabriel

    2000-03-01

    Day/night variations in the size distribution of the particulate matter >0.15 mm (PM) were studied in May 1995 during the DYNAPROC time-series cruise in the northwestern Mediterranean Sea. Data on vertical distributions of PM (>0.15 mm) and zooplankton were collected with the Underwater Video Profiler (UVP). The comparisons of the UVP data with plankton net data and POC data from water bottles indicated that more than 97% of the particles detected by the UVP were non-living particles (0.15 mm) and that the PM contributed 4-34% of the total dry weight measured on GF/F filters. Comparison of seven pairs of day and night vertical profiles performed during the cruise showed that in the upper 800 m, the mean size and the volume of particles was higher at night than during the day. During the night, the integrated volume of the PM increased on average by 32±20%. This increase corresponded to a shift of smaller size classes (<0.5 mm) towards the larger ones (>0.5 mm). During the day, the pattern was reversed, and the quantity of PM >0.5 mm decreased. During the study period, the standing stock of PM (60-800 m) decreased from 7.5 to less than 2 g m -2 but the diel variations persisted, except for two short periods in the superficial layer following a wind event. The cyclic feeding activity induced by the diel vertical migration of zooplankton could be the best candidate to explain the observed diel fluctuations in the size classes of PM in the water column. However, our results also suggest that in the upper layer additional driving forces such as the increase of the level of turbulence after a wind event or the modification of the zoo- and phytoplankton community can influence the PM temporal evolution.

  9. Giant low-field magnetocaloric effect in single-crystalline EuTi{sub 0.85}Nb{sub 0.15}O{sub 3}

    SciTech Connect

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

    2016-02-01

    The magnetocaloric effect in ferromagnetic single crystal EuTi{sub 0.85}Nb{sub 0.15}O{sub 3} has been investigated using magnetization and heat capacity measurements. EuTi{sub 0.85}Nb{sub 0.15}O{sub 3} undergoes a continuous ferromagnetic phase transition at T{sub C} = 9.5 K due to the long range ordering of magnetic moments of Eu{sup 2+} (4f{sup 7}). With the application of magnetic field, the spin entropy is strongly suppressed and a giant magnetic entropy change is observed near T{sub C}. The values of entropy change ΔS{sub m} and adiabatic temperature change ΔT{sub ad} are as high as 51.3 J kg{sup −1} K{sup −1} and 22 K, respectively, for a field change of 0–9 T. The corresponding magnetic heating/cooling capacity is 700 J kg{sup −1}. This compound also shows large magnetocaloric effect even at low magnetic fields. In particular, the values of ΔS{sub m} reach 14.7 and 23.8 J kg{sup −1} K{sup −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 EuTi{sub 0.85}Nb{sub 0.15}O{sub 3} a very promising candidate for low temperature magnetic refrigeration.

  10. 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.

  11. Coexistence of long-ranged magnetic order and superconductivity in the pnictide superconductor SmFeAsO1-xFx (x=0,0.15)

    NASA Astrophysics Data System (ADS)

    Ryan, D. H.; Cadogan, J. M.; Ritter, C.; Canepa, F.; Palenzona, A.; Putti, M.

    2009-12-01

    Powder neutron-diffraction measurements on both SmFeAsO and the fluorine-doped superconductor, SmFeAsO0.85F0.15 , show that the Sm sublattice orders magnetically. In both cases we observe a simple layered antiferromagnetic arrangement of the ˜0.5μB Sm moments. This provides direct evidence that long-ranged magnetic order of the samarium moments coexists with superconductivity in the SmFeAsO1-xFx system.

  12. 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.

  13. 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.

  14. 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.

  15. LIQUIDARMOR CM Flashing and Sealant, High Impact Technology Demonstration

    SciTech Connect

    Hun, Diana E.; Bhandari, Mahabir S.

    2016-12-01

    Air leakage is responsible for about 1.1 quads of energy or 6% of the total energy used by commercial buildings in the US. Consequently, infiltration and exfiltration are among the largest envelope-related contributors to the heating, ventilation, and air conditioning loads in commercial buildings. New air sealing technologies have recently emerged that aim to improve the performance of air barrier systems by simplifying their installation procedure. LIQUIDARMORTM CM Flashing and Sealant is an example of these new advanced material technologies. This technology is a spray-applied sealant and liquid flashing and can span gaps that are up to ¼ in. wide without a supporting material. ORNL verified the performance of LIQUIDARMORTM CM with field tests and energy simulations from a building in which LIQUIDARMORTM CM was one of components of the air barrier system. The Homeland Security Training Center (HTC) at the College of DuPage in Glen Ellyn, IL, served as the demonstration site. Blower door test results show the average air leakage rate in the demonstration site to be 0.15 cfm/ft2 at 1.57 psf, or 63% lower than the 0.4 cfm at 1.57 psf specified in the 2015 International Energy Conservation Code (IECC). According to simulation results, HTC lowered its annual heating and cooling cost by about $3,000 or 9% compared to a similar building that lacked an air barrier system. This demonstration project serves as an example of the level of building envelope airtightness that can be achieved by using air barrier materials that are properly installed, and illustrates the energy and financial savings that such an airtight envelope could attain.

  16. Parallel processing: The Cm/sup */ experience

    SciTech Connect

    Siewiorek, D.; Gehringer, E.; Segall, Z.

    1986-01-01

    This book describes the parallel-processing research with CM/sup */ at Carnegie-Mellon University. Cm/sup */ is a tightly coupled 50-processor multiprocessing system that has been in operation since 1977. Two complete operating systems-StarOS and Medusa-are part of its development along with a number of applications.

  17. Continuously tunable temperature coefficient of resistivity in antiperovskite AgN1-xCxMn3 (0 ≤ x ≤ 0.15)

    NASA Astrophysics Data System (ADS)

    Lin, J. C.; Tong, P.; Lin, S.; Wang, B. S.; Song, W. H.; Sun, Y. P.

    2014-12-01

    The antiperovskite intermetallic compounds AgN1-xCxMn3 (0 ≤ x ≤ 0.15) have been synthesized. As x increases, the temperature coefficient of resistivity (TCR) above room temperature decreases monotonically and finally changes the sign from positive to negative above x = 0.1. Meanwhile, the temperature range is gradually broadened. For x = 0.07, TCR is ˜3.1 ppm/K between 280 K and 375 K. Both the resistivity and its slope are insensitive to the external magnetic field, indicating an insignificant contribution from magnetic scattering or short-range magnetic ordering to the observed low-TCR. As manifested by the Hall effect, the charge carrier density in the paramagnetic state for x = 0.15 is reduced by an order of magnitude in comparison with that for x = 0. The reduction of carrier density and the enhancive disorders when x increases was proposed to be responsible for the decrease in TCR and its sign switch.

  18. Electron-Phonon Anomaly Related to Charge Stripes: Static Stripe Phase Versus Optimally Doped Superconducting La1.85Sr0.15CuO4

    NASA Astrophysics Data System (ADS)

    Reznik, D.; Pintschovius, L.; Fujita, M.; Yamada, K.; Gu, G. D.; Tranquada, J. M.

    2007-05-01

    Inelastic neutron scattering was used to study the Cu-O bond-stretching vibrations in optimally doped La1.85Sr0.15CuO4 (Tc = 35 K) and in two other cuprates showing static stripe order at low temperatures, i.e. La1.48Nd0.4Sr0.12CuO4 and La1.875Ba0.125CuO4. All three compounds exhibit a very similar phonon anomaly, which is not predicted by conventional band theory. It is argued that the phonon anomaly reflects a coupling to charge inhomogeneities in the form of stripes, which remain dynamic in superconducting La1.85Sr0.15CuO4 down to the lowest temperatures. These results show that the phonon effect indicating stripe formation is not restricted to a narrow region of the phase diagram around the so-called 1/8 anomaly but occurs in optimally doped samples as well.

  19. Interference effects of thrust reversing on horizontal tail effectiveness of twin-engine fighter aircraft at Mach numbers from 0.15 to 0.90

    NASA Technical Reports Server (NTRS)

    Capone, F. J.; Mason, M. L.

    1984-01-01

    An investigation was conducted in the Langley 16 foot Transonic Tunnel to determine the interference effects of thrust reversing on horizontal tail effectiveness of a twin engine, general research fighter model at approach and in-flight speeds. Twin vertical tails at three longitudinal locations were tested at a cant angle of 0 deg. One configuration was also tested at a cant angle of 20 deg. Two nonaxisymmetric nozzle reverser concepts were studied. Test data were obtained at Mach numbers of 0.15, 0.60, and 0.90 and at angles of attack from -3 to 9 deg. Nozzle pressure ratios varied from jet off to 7.0, depending upon Mach number. At landing approach speed (Mach number 0.15), thrust reverser operation usually resulted in large variations (up to 70% increase) in horizontal tail effectiveness as nozzle pressure ratio was varied at zero angle of attack or as angle of attack was varied at constant nozzle pressure ratio. There was always a decrease in effectiveness at Mach numbers of 0.60 and 0.90 as a result of reverser operation.

  20. Rounding of a first-order magnetic phase transition in La0.7Ca0.3Mn0.85Ni0.15O3

    NASA Astrophysics Data System (ADS)

    Phan, The-Long; Zhang, P.; Zhang, Y. D.; Grinting, D.; Thanh, T. D.; Yu, S. C.

    2013-05-01

    We prepared a polycrystalline sample of orthorhombic La0.7Ca0.3Mn0.85Ni0.15O3, and then studied its critical behavior. Based on the Landau phase-transition theory and Banerjee's criteria, we have found the sample undergoing a second-order magnetic phase transition. This continuous transition is characterized by critical parameters of TC = 170 K, β = 0.320 ± 0.009, γ = 0.990 ± 0.082, and δ = 4.09 ± 0.17 determined from modified Arrott plots. With these values, the magnetization-field-temperature (M-H-T) behaviors of La0.7Ca0.3Mn0.85Ni0.15O3 below and above TC are well described by an equation of state M(H ,ɛ)=ɛβf±(H /ɛβ +γ), where ɛ =(T -TC)/TC, f+ for T > TC and f- for T < TC. Having compared to the theoretical models, the critical-exponent values determined in our case are close to those expected for the 3D Ising model and mean-field theory. This indicates an existence of ferromagnetic short-range interactions in the system below TC. The nature of the transformation from first-order to second-order phase transitions related to the Ni doping is discussed in detail.

  1. Carbon Sequestration in Reclaimed Mined Soils of Ohio

    SciTech Connect

    M.K. Shukla; R. Lal

    2004-04-01

    This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites were characterized by distinct age chronosequences of reclaimed minesoil and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites are owned and maintained by Americal Electrical Power. These sites were reclaimed (1) with topsoil application, and (2) without topsoil application, and were under continuous grass or forest cover. Three core and three bulk soil samples were collected from each of the experimental site and one unmined site (UMS) for 0-15 cm and 15-30 cm depths and soil bulk density ({rho}{sub b}), texture, saturated hydraulic conductivity (Ks), volumes of transport (VTP) and storage (VSP) pores, available water capacity (AWC), pH and electrical conductivity (EC), SOC, total nitrogen (TN) concentrations and stocks were determined. The preliminary results from sites reclaimed with topsoil and grass indicate that sand content was highest (24%) and clay content was lowest (17%) for site reclaimed in 2003 (R03) for 0-15 cm depth. The {rho}{sub b} was highest for R03 (1.24 Mg m{sup -3}) than sites reclaimed in 1987 (R87; 1.02 Mg m{sup -3}), 1978 (R78; 0.98 Mg m{sup -3}) and UMS (0.96 Mg m{sup -3}) for 0-15 cm depth. No significant differences were observed in Ks, VTP, VSP, AWC among these sites (P<0.05). For 15-30 cm depth {rho}{sub b} varied in the order R03 (1.61 Mg m{sup -3})> R87 (1.42 Mg m{sup -3}) = R78 (1.40 Mg m{sup -3}) = UMS (1.34 Mg m{sup -3}). Soil pH was > 5.5 and EC < 4 dS m{sup -1} for all sites and depths and was favorable for grass growth. The SOC and TN stocks were lower in R03 (3.5 Mg ha{sup -1} and 0.6 Mg ha{sup -1}; respectively) than R78 (30.1 Mg ha{sup -1} and 1.6 Mg ha{sup -1}) and UMS (18.7 Mg ha{sup -1} and 1.8 Mg ha{sup -1}) for 0-15 cm depth. The SOC and TN stocks were also lower in R03 (2.9 Mg ha{sup -1}and 0.8 Mg ha{sup -1}; respectively) than R87 (22

  2. The relative importance of vertical soil nutrient heterogeneity, and mean and depth-specific soil nutrient availabilities for tree species richness in tropical forests and woodlands.

    PubMed

    Shirima, Deo D; Totland, Ørjan; Moe, Stein R

    2016-11-01

    The relative importance of resource heterogeneity and quantity on plant diversity is an ongoing debate among ecologists, but we have limited knowledge on relationships between tree diversity and heterogeneity in soil nutrient availability in tropical forests. We expected tree species richness to be: (1) positively related to vertical soil nutrient heterogeneity; (2) negatively related to mean soil nutrient availability; and (3) more influenced by nutrient availability in the upper than lower soil horizons. Using a data set from 60, 20 × 40-m plots in a moist forest, and 126 plots in miombo woodlands in Tanzania, we regressed tree species richness against vertical soil nutrient heterogeneity, both depth-specific (0-15, 15-30, and 30-60 cm) and mean soil nutrient availability, and soil physical properties, with elevation and measures of anthropogenic disturbance as co-variables. Overall, vertical soil nutrient heterogeneity was the best predictor of tree species richness in miombo but, contrary to our prediction, the relationships between tree species richness and soil nutrient heterogeneity were negative. In the moist forest, mean soil nutrient availability explained considerable variations in tree species richness, and in line with our expectations, these relationships were mainly negative. Soil nutrient availability in the top soil layer explained more of the variation in tree species richness than that in the middle and lower layers in both vegetation types. Our study shows that vertical soil nutrient heterogeneity and mean availability can influence tree species richness at different magnitudes in intensively utilized tropical vegetation types.

  3. Effects of fertilizer on inorganic soil N in East Africa maize systems: vertical distributions and temporal dynamics.

    PubMed

    Tully, Katherine L; Hickman, Jonathan; McKenna, Madeline; Neill, Christopher; Palm, Cheryl A

    2016-09-01

    Fertilizer applications are poised to increase across sub-Saharan Africa (SSA), but the fate of added nitrogen (N) is largely unknown. We measured vertical distributions and temporal variations of soil inorganic N following fertilizer application in two maize (Zea mays L.)-growing regions of contrasting soil type. Fertilizer trials were established on a clayey soil in Yala, Kenya, and on a sandy soil in Tumbi, Tanzania, with application rates of 0-200 kg N/ha/yr. Soil profiles were collected (0-400 cm) annually (for three years in Yala and two years in Tumbi) to examine changes in inorganic N pools. Topsoils (0-15 cm) were collected every 3-6 weeks to determine how precipitation and fertilizer management influenced plant-available soil N. Fertilizer management altered soil inorganic N, and there were large differences between sites that were consistent with differences in soil texture. Initial soil N pools were larger in Yala than Tumbi (240 vs. 79 kg/ha). Inorganic N pools did not change in Yala (277 kg/ha), but increased fourfold after cultivation and fertilization in Tumbi (371 kg/ha). Intra-annual variability in NO(-)3 -N concentrations (3-33 μg/g) in Tumbi topsoils strongly suggested that the sandier soils were prone to high leaching losses. Information on soil inorganic N pools and movement through soil profiles can h vulnerability of SSA croplands to N losses and determine best fertilizer management practices as N application rates increase. A better understanding of the vertical and temporal patterns of soil N pools improves our ability to predict the potential environmental effects of a dramatic increase in fertilizer application rates that will accompany the intensification of African croplands.

  4. [Effects of wheat-straw returning into paddy soil on dissolved organic carbon contents and rice grain yield].

    PubMed

    Xu, Ke; Liu, Meng; Chen, Jing-du; Gu, Hai-yan; Dai, Qi-gen; Ma, Ke-qiang; Jiang, Feng; He, Li

    2015-02-01

    A tank experiment using conventional rice cultivar Nanjing 44 as experimental material was conducted at the Experimental Farm of Yangzhou University to investigate the dynamics of wheat straw decomposition rate and the amount of carbon release in clay and sandy soils, as well as its effects on the content of dissolved organic carbon (DOC) and rice yield. The two rates of wheat straw returning were 0 and 6000 kg · hm(-2), and three N application levels were 0, 225, 300 kg · hm(-2). The results showed that, the rate of wheat straw decomposition and the amount of carbon release in clay and sandy soils were highest during the initial 30 days after wheat straw returning, and then slowed down after, which could be promoted by a higher level of nitrogen application. The rate of wheat straw decomposition and the amount of carbon release in clay soil were higher than that in sandy soil. The DOC content in soil increased gradually with wheat straw returning into paddy soil and at the twenty-fifth day, and then decreased gradually to a stable value. The DOC content at the soil depth of 15 cm was significantly increased by wheat straw returning, but not at the soil depth of 30 cm and 45 cm. It was concluded that wheat straw returning increased the DOC content in the soil depth of 0-15 cm mainly. N application decreased the DOC content and there was no difference between the two N application levels. Straw returning decreased the number of tillers in the early growth period, resulted in significantly reduced panicles per unit area, but increased spikelets per panicle, filled-grain percentages, 1000-grain mass, and then enhanced grain yield.

  5. 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.

  6. Conducting Retrospective Ontological Clinical Trials in ICD-9-CM in the Age of ICD-10-CM

    PubMed Central

    Venepalli, Neeta K; Shergill, Ardaman; Dorestani, Parvaneh; Boyd, Andrew D

    2014-01-01

    OBJECTIVE To quantify the impact of International Classification of Disease 10th Revision Clinical Modification (ICD-10-CM) transition in cancer clinical trials by comparing coding accuracy and data discontinuity in backward ICD-10-CM to ICD-9-CM mapping via two tools, and to develop a standard ICD-9-CM and ICD-10-CM bridging methodology for retrospective analyses. BACKGROUND While the transition to ICD-10-CM has been delayed until October 2015, its impact on cancer-related studies utilizing ICD-9-CM diagnoses has been inadequately explored. MATERIALS AND METHODS Three high impact journals with broad national and international readerships were reviewed for cancer-related studies utilizing ICD-9-CM diagnoses codes in study design, methods, or results. Forward ICD-9-CM to ICD-10-CM mapping was performing using a translational methodology with the Motif web portal ICD-9-CM conversion tool. Backward mapping from ICD-10-CM to ICD-9-CM was performed using both Centers for Medicare and Medicaid Services (CMS) general equivalence mappings (GEMs) files and the Motif web portal tool. Generated ICD-9-CM codes were compared with the original ICD-9-CM codes to assess data accuracy and discontinuity. RESULTS While both methods yielded additional ICD-9-CM codes, the CMS GEMs method provided incomplete coverage with 16 of the original ICD-9-CM codes missing, whereas the Motif web portal method provided complete coverage. Of these 16 codes, 12 ICD-9-CM codes were present in 2010 Illinois Medicaid data, and accounted for 0.52% of patient encounters and 0.35% of total Medicaid reimbursements. Extraneous ICD-9-CM codes from both methods (Centers for Medicare and Medicaid Services general equivalent mapping [CMS GEMs, n = 161; Motif web portal, n = 246]) in excess of original ICD-9-CM codes accounted for 2.1% and 2.3% of total patient encounters and 3.4% and 4.1% of total Medicaid reimbursements from the 2010 Illinois Medicare database. DISCUSSION Longitudinal data analyses post-ICD-10

  7. Flux creep and irreversibility in electron-doped Pr 1.85Th 0.15CuO 4- y

    NASA Astrophysics Data System (ADS)

    Peng, J. L.; Greene, R. L.

    1990-12-01

    High-quality crystallites of Pr 1.85Th 0.15CuO 4- y were prepared by a solid state reaction technique and aligned in epoxy by a magnetic field. Magnetic relaxation of the remanent moment was measured with field H parallel to the ab plane. We interpret our data with a thermally activated flux creep model, and show that effective pinning energy U0 increases with increasing T between 2 and 15 K. We find that U0 is not strongly dependent on applied field. The crossover from reversible to irreversible magnetization was found to follow the power law H= H(0)(1- T/ Tc) 1.7. The value of U0 for H parallel to the ab plane is found to vary from ≈8 to ≈40 meV between 2 and 15 K, respectively. Compared to YBCO, pinning in the electron-doped system is rather weak.

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

    SciTech Connect

    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.

    2016-07-22

    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. In conclusion, the room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.

  9. Elastic anomalies in a La 1.85Sr 0.15CuO 4 single crystal under high magnetic fields

    NASA Astrophysics Data System (ADS)

    Hanaguri, Tetsuo; Fukase, Tetsuo; Suzuki, Takao; Tanaka, Isao; Kojima, Hironao

    1994-02-01

    Temperature dependence of the sound velocity Vs in a La 1.85Sr 0.15CuO 4 single crystal has been measured in the ( c11 - c12)/2 mode and in the c33 mode under high magnetic fields up to 23T. In the field above 6T, Vs in the ( c11 - c12)/2 mode anomalously decreases with decreasing temperature, followed by the increase below about 10K. In the c33 mode, similar behavior of Vs can be observed above 20T. Such a temperature dependence of Vs may suggest the existence of a strain sensitive narrow band near the Fermi level or a phase transition related to the flux line lattice.

  10. 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.

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

    SciTech Connect

    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.

  12. Noise performance at cryogenic temperatures at AlGaAs/InGaAs HEMT's with 0.15- mu m T-shaped WSi/sub x/ gates

    NASA Astrophysics Data System (ADS)

    Joshin, K.; Mimino, Y.; Ohmura, S.; Hirachi, Y.

    1992-03-01

    T-shaped 0.15-μm WSix gate HEMTs have been fabricated on AlGaAs/InGaAs MBE wafers. Their S-parameters, output noise spectral density Pno, and noise temperatures T e at cryogenic temperatures, were measured. The current gain cutoff frequency fT increases from 61 GHz at 295 K to 87 GHz at 90 K. Pno and Te measurements indicate that the hot-electron effect is noticeable at low temperatures at high drain current. At 30 GHz, the noise temperature is 19±3 K with an associated gain of 10.4 dB at the physical temperature of 20 K. The results demonstrate the great potential of AlGaAs/InGaAs HEMTs for low-temperature applications.

  13. 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.

  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. Correlation of electrical, magnetic, and thermal properties of the La0.85Ag0.15MnO3 manganite near the phase transition temperature

    NASA Astrophysics Data System (ADS)

    Gamzatov, A. G.; Batdalov, A. B.; Kaul', A. R.; Mel'nikov, O. V.

    2011-01-01

    The correlation between electrical, magnetic, and lattice properties of manganites has been studied by analyzing the temperature dependence of the electrical resistivity of the La0.85Ag0.15MnO3 manganite. The results have been discussed within the model of a phase-separated manganite in terms of the percolation theory. It has been shown that, from analyzing the temperature and magnetic field dependences of the electrical resistivity, it is possible to predict the behavior of the magnetization and specific heat, as well as the change of magnetic entropy near the phase transition temperature, and that the obtained agreement with experimental data for this analysis is quite reasonable.

  16. 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.

  17. Evaluation of irradiation hardening of ion-irradiated V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys by nanoindentation techniques

    NASA Astrophysics Data System (ADS)

    Miyazawa, Takeshi; Nagasaka, Takuya; Kasada, Ryuta; Hishinuma, Yoshimitsu; Muroga, Takeo; Watanabe, Hideo; Yamamoto, Takuya; Nogami, Shuhei; Hatakeyama, Masahiko

    2014-12-01

    Irradiation hardening behavior of V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys after Cu-ion beam irradiation were investigated with a combination between nanoindentation techniques and finite element method (FEM) analysis. The ion-irradiation experiments were conducted at 473 K with 2.4 MeV Cu2+ ions up to 7.6 dpa. For the unirradiated materials, the increase in nanoindentation hardness with decreasing indentation depth, so-called indentation size effect (ISE), was clearly observed. After irradiation, irradiation hardening in the measured depth was identified. Hardening behavior of bulk-equivalent hardness for V-4Cr-4Ti-0.15Y alloy was similar to that for V-4Cr-4Ti alloy. Y addition has little effect on irradiation hardening at 473 K. Adding the concept of geometrically necessary dislocations (GNDs) to constitutive equation of V-4Cr-4Ti alloy, the ISE was simulated. A constant value of α = 0.5 was derived as an optimal value to simulate nanoindentation test for ion-irradiated V-4Cr-4Ti alloy. Adding the term of irradiation hardening Δσirrad. to constitutive equation with α = 0.5, FEM analyses for irradiated surface of V-4Cr-4Ti alloy were carried out. The analytic data of FEM analyses based on neutron-irradiation hardening equivalent to 3.0 dpa agreed with the experimental data to 0.76 dpa. The comparison indicates that irradiation hardening by heavy ion-irradiation is larger than that by neutron-irradiation at the same displacement damage level. Possible mechanisms for extra hardening by heavy ion-irradiation are the processes that the injected Cu ions could effectively produce irradiation defects such as interstitials compared with neutrons, and that higher damage rate of ion-irradiation enhanced nucleation of irradiation defects and hence increased the number density of the defects compared with neutron-irradiation.

  18. Reflectance-Based Estimation of Soil Heat Fluxes in the Texas High Plains

    NASA Astrophysics Data System (ADS)

    Gowda, P. H.; Colaizzi, P. D.; O'Shaughnessy, S.; Ha, W.; Howell, T. A.

    2010-12-01

    Soil heat flux (G) is one of the terms required for estimating evapotranspiration rates using an energy balance. Numerous reflectance-based models are available in the literature for estimating G fluxes. However, these models have shown wide variation in their performance. Therefore, operational ET remote sensing programs may require locally developed/calibrated models for accurately estimating G. The objective of this study was to develop and evaluate reflectance-based empirical G models for the semi-arid Texas High Plains. Soil heat flux was measured at 0.15 hz interval and averaged every 15 minutes at five different locations within a 4.7 ha lysimeter field with Pullman clay loam soil during the 2010 summer growing season. The field was planted to soybean and managed under dryland conditions. In each location, G was measured at 8 cm depth with two Campbell Scientific HFT3 soil heat flux plates. Soil temperature was measured at 2 and 6 cm above the soil heat flux plates. Soil moisture was measured in the 2-8 cm layer using Acclima SDI-12 sensors. Hourly G fluxes at the surface were calculated by adding the measured G fluxes at 8 cm to the energy stored above the heat flux plates. A multispectral radiometer (MSR, CROPSCAN, Inc.) and hand-held thermometer (EVEREST Interscience Inc.) measured surface reflectance in red and near infrared bandwidths and surface temperature (ST), respectively, daily at 11:30 AM CST to be consistent with the Landsat 5 overpass time. Fraction crop cover (FC) was measured by digital photographs taken twice a week. A set of G models was developed for estimating hourly fluxes based on measured reflectance, net radiation, ST, NDVI, and FC,. Resulting models were compared for performance with existing models available in the literature. In this presentation, we will discuss our G models for the Texas High Plains and the statistical results.

  19. Precision of farmer-based fertility ratings and soil organic carbon for crop production on a Ferralsol

    NASA Astrophysics Data System (ADS)

    Musinguzi, P.; Ebanyat, P.; Tenywa, J. S.; Basamba, T. A.; Tenywa, M. M.; Mubiru, D.

    2015-09-01

    Simple and affordable soil fertility ratings are essential, particularly for the resource-constrained farmers in sub-Saharan Africa (SSA), in planning and implementing prudent interventions. A study was conducted on Ferralsols in Uganda to evaluate farmer-based soil fertility assessment techniques, hereafter referred to as farmers' field experiences (FFE), for ease of use and precision, against more formal scientific quantitative ratings using soil organic carbon (SQR-SOC). A total of 30 fields were investigated and rated using both techniques, as low, medium and high in terms of soil fertility - with maize as the test crop. Both soil fertility rating techniques were fairly precise in delineating soil fertility classes, though the FFE was inefficient in distinguishing fields > 1.2 % SOC with medium and high fertility. Soil organic carbon, silt and clay were exceptionally influential, accounting for the highest percentage in grain yield of 50 % in the topsoil (0-15 cm) and 67 % for the mean concentrations from 0 to 15 and 15 to 30 cm. Each unit increase in SOC concentration resulted in 966 to 1223 kg ha-1 yield gain. The FFE technique was effective in identifying low-fertility fields, and this was coherent with the fields categorized as low (SOC < 1.2 %). Beyond this level, its precision can be remarkably increased when supplemented with the SQR-SOC technique.

  20. Detections of 2 cm formaldehyde emissions towards Galactic star-forming regions with 6 cm counterpart

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Shen, Zhi-Qiang; Li, Xiao-Qiong; Yang, Kai; Li, Juan; Wang, Jun-Zhi; Wu, Ya-Jun; Zhao, Rong-Bin; Wang, Jin-Qing; Dong, Jian; Jiang, Dong-Rong; Li, Bin

    2017-01-01

    We report the detections of H2CO emission at the 2 cm transition towards Galactic star-forming regions with known 6 cm counterpart using the Shanghai Tianma Radio Telescope (TMRT). One significant detection (in NGC7538) and two possible detections (in G23.01-0.41 and G29.96-0.02) were made. Comparing with previous observations, we found that there is a time lag of appearance of 2 cm and 6 cm emissions detected in NGC7538, contradicting with the prediction of radiative pumping via radio continuum radiation. Combinations of the variability of 6 cm masers in NGC7538 suggest that collisional pumping via high-velocity shocks could better explain the 6 cm H2CO maser emission. Under this scheme, excitation of the 2 cm maser may require a higher collision energy compared to the 6 cm transition.

  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. (Bi0.15La0.27Sr0.53)(Co0.25Fe0.75)O3-δ perovskite: A novel cathode material for intermediate temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Khaerudini, Deni S.; Guan, Guoqing; Zhang, Peng; Xiaoketi, Pairuzha; Hao, Xiaogang; Wang, Zhongde; Kasai, Yutaka; Abudula, Abuliti

    2016-12-01

    Perovskite oxides (Bi0.15La0.27Sr0.53)x(Co0.25Fe0.75)O3-δ (BiLSCFx, x = 0.8, 0.9, 1.0, 1.1) have been synthesized by solid state reaction and evaluated as a novel cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The effects of A-site variations on lattice structure, calcination temperature, oxygen desorption and electrochemical properties of BiLSCFx are investigated. This kind of material has perfectly cubic structure based on the Pm-3m space group whose lattice size increases with x, which is thermally stable after calcination and shows desirable chemical compatibility with La0.8Sr0.2Ga0.8Mg0.2O3-δ electrolyte at 1150 °C for 8 h under air atmosphere. Among those A-site variations, it is found that BiLSCF0.9 demonstrates the best cathode performance. It has the minimum polarization resistance value of 0.039 Ω cm2 at 700 °C and α-oxygen desorbed about 0.031 mmol g-1, indicating a good reactivity and strong adsorbate of O2. The single cell with BiLSCF0.9 cathode delivers a power density of 0.66 W cm-2 at 700 °C with humidified H2 (∼3% H2O) as the fuel and ambient air as the oxidant. In addition, the cell shows sufficient stability with ∼9% degradation over 75 h at 600 °C. It indicates that BiLSCF0.9 is a promising candidate for application as cathode material in IT-SOFCs.

  3. 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.

  4. Transport of Alachlor, Atrazine, Dicamba, and Bromide through Silt and Loam Soils

    NASA Astrophysics Data System (ADS)

    Tindall, J. A.

    2015-12-01

    The herbicides alachlor, atrazine, and dicamba, as well as bromide were applied to soils overlying the High Plains aquifer in Nebraska, to both macropore and non-macropore sites. Three of 6 study areas (exhibiting a high percentage of macropores) were used for analysis of chemical transport. Twelve intact soil cores (30 cm diameter; 40 cm height), were excavated (two each from 0-40 cm and 40-80 cm depths). The first three study areas and soil cores were used to study preferential flow characteristics using dye staining and to determine hydraulic properties; the remaining cores were treated the same as field macropore sites. Two undisturbed experimental field plots, each with a 1 m2 surface area, were established in each of the three macropore study areas. Each preferential plot was instrumented with suction lysimeters, tensiometers, and neutron access tubes - 10 cm increments to 80 cm - and planted in corn. Three study areas that did not exhibit macropores had alachlor, atrazine, and dicamba and bromide disked into the top 15 cm of soil; concentrations were tracked for 120 days - samples were collected on a grid, distributed within 3 plots measuring 50 m x 50 m each. Core samples were collected prior to and immediately after application, and then at 30, 60, and 120 days after application. Each lab core sample was in 15-cm lengths from 0-15 cm, 15-30 cm, 45-60 cm, and 75-90 cm. For areas exhibiting macropores, herbicides had begun to move between 10-15 days after application with concentrations peaking at various depths after heavy rainfall events. Field lysimeter samples showed increases in concentrations of herbicides at depths where laboratory data indicated greater percentages of preferential flowpaths. Concentrations of atrazine, alachlor and dicamba exceeding 0.30, 0.30, and 0.05 μg m1-1 respectively were observed with depth (10-30 cm and 50-70 cm) after two months following heavy rainfall events indicating that preferential flowpaths were a significant

  5. Phragmites australis + Typha latifolia Community Enhanced the Enrichment of Nitrogen and Phosphorus in the Soil of Qin Lake Wetland.

    PubMed

    Ge, Zhiwei; An, Ran; Fang, Shuiyuan; Lin, Pengpeng; Li, Chuan; Xue, Jianhui; Yu, Shuiqiang

    2017-01-01

    Aquatic plants play an essential role and are effective in mitigating lake eutrophication by forming complex plant-soil system and retaining total nitrogen (TN) and phosphorus (TP) in soils to ultimately reduce their quantities in aquatic systems. Two main vegetation types (Phragmites australis community and P. australis + Typha latifolia community) of Qin Lake wetland were sampled in this study for the analysis of TN and TP contents and reserves in the wetland soils. The results showed that (1) the consumption effect of Qin Lake wetland on soluble N was much more significant than on soluble P. (2) The efficiency of TN enrichment in wetland soil was enhanced by vegetation covering of P. australis and T. latifolia. (3) Wetland soil P was consumed by P. australis community and this pattern was relieved with the introduction of T. latifolia. (4) According to the grey relativity analysis, the most intensive interaction between plants and soil occurred in summer. In addition, the exchange of N in soil-vegetation system primarily occurred in the 0-15cm soil layer. Our results indicated that vegetation covering was essential to the enrichment of TN and TP, referring to the biology-related fixation in the wetland soil.

  6. 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.

  7. Radiocarbon measurements of soil organic matter (SOM) and soil CO2 efflux provide unique insights into the SOM dynamics of managed loblolly pine plantations

    NASA Astrophysics Data System (ADS)

    Vogel, J. G.; Schuur, E. A.; Bracho, R.; Jokela, E. J.

    2011-12-01

    Soil organic matter (SOM) cycling between soils and the atmosphere affects a wide range of important ecosystem functions. However the key processes controlling this cycle, fine root inputs and heterotrophic respiration, are poorly understood primarily because they are difficult to directly measure in the field. Radiocarbon measurements and simple models can be used to evaluate the relative influence of these processes on SOM cycling. Here we used radiocarbon measurements of density separated SOM, and root respiration, microbial respiration, and soil CO2 efflux to examine the relative effect of two forestry practices, fertilization and the genetic control of planted seedlings, on SOM cycling in two loblolly pine plantation forests in north central Florida. Our primary hypothesis was that greater aboveground growth would correspond to increased inputs of C to the soil as root biomass, and a greater efflux of CO2 from roots and soil microbes. For the density separated fractions, the light fraction (LF) (<1.6 g cm-3) was nearly 98% of the SOM in these sandy soils, and the LF decreased significantly (p<0.05) with increasing levels of fertilization for the A horizon (~0-30 cm). Light fraction radiocarbon values ranged from 66-127% and tended to be more enriched in bomb carbon, or older, with increasing levels of fertilization. Based on a significant reduction in fine root biomass with fertilization, we estimate that the smaller mass of the LF and its older age were the result of less fine root contributions of C to the LF pool. The alternative hypothesis, that fertilization increased SOM turnover, was not supported. To determine if changes in root biomass reflected changes in root respiration in soil CO2 efflux, we estimated radiocarbon values for root and microbial respiration, and soil CO2 efflux in order to partition the components in soil CO2 efflux. Radiocarbon estimates of microbial respiration (0-15 cm depth) and root respiration fractions ranged from 55-67% and

  8. 21 CM searches for DIM galaxies

    NASA Astrophysics Data System (ADS)

    Disney, Mike; Banks, Gareth

    1997-04-01

    We review very strong selection effects which operate against the detection of dim (i.e. low surface brightness) galaxies. The Parkes multibeam instrument offers a wonderful opportunity to turn up new populations of such galaxies. However, to explore the newly accessible parameter space, it will be necessary to survey both a very deep patch (105 s/pointing, limiting N hi ˜ 1018 cm-2) and a deep patch (104 s/pointing, limiting N hi ˜ 3 × 1018 cm-2) in carefully selected areas, and we outline the case to do this.

  9. A novel lead compound CM-118

    PubMed Central

    Meng, Lanfang; Shu, Mengjun; Chen, Yaqing; Yang, Dexiao; He, Qun; Zhao, Hui; Feng, Zhiyong; Liang, Chris; Yu, Ker

    2014-01-01

    The anaplastic lymphoma kinase (ALK) and the c-Met receptor tyrosine kinase play essential roles in the pathogenesis in multiple human cancers and present emerging targets for cancer treatment. Here, we describe CM-118, a novel lead compound displaying low nanomolar biochemical potency against both ALK and c-Met with selectivity over >90 human kinases. CM-118 potently abrogated hepatocyte growth factor (HGF)-induced c-Met phosphorylation and cell migration, phosphorylation of ALK, EML4-ALK, and ALK resistance mutants in transfected cells. CM-118 inhibited proliferation and/or induced apoptosis in multiple c-Met- and ALK-addicted cancer lines with dose response profile correlating target blockade. We show that the CM-118-induced apoptosis in c-Met-amplified H1993 NSCLC cells involved a rapid suppression of c-Met activity and c-Met-to-EGFR cross-talk, and was profoundly potentiated by EGFR inhibitors as shown by the increased levels of apoptotic proteins cleaved-PARP and Bim as well as reduction of the survival protein Mcl-1. Bim-knockdown or Mcl-1 overexpression each significantly attenuated apoptosis. We also revealed a key role by mTOR in mediating CM-118 action against the EML4-ALK-dependent NSCLC cells. Abrogation of EML4-ALK in H2228 cells profoundly reduced signaling capacity of the rapamycin-sensitive mTOR pathway leading to G1 cell cycle arrest and mitochondrial hyperpolarization, a metabolic perturbation linked to mTOR inhibition. Depletion of mTOR or mTORC1 inhibited H2228 cell growth, and mTOR inhibitors potentiated CM-118’s antitumor activity in vitro and in vivo. Oral administration of CM-118 at a wide range of well tolerated dosages diminished c-Met- and ALK phosphorylation in vivo, and caused tumor regression or growth inhibition in multiple c-Met- and ALK-dependent tumor xenografts in mice. CM-118 exhibits favorable pharmacokinetic and drug metabolism properties hence presents a candidate for clinical evaluation. PMID:24618813

  10. Effects of Conservation Agriculture on Soil Physical Properties and Yield of Lentil in Northern Syria

    NASA Astrophysics Data System (ADS)

    Wahbi, Ammar; Miwak, Hisham; Singh, Raphy

    2014-05-01

    Conservation agriculture (CA) aims to achieve sustainable and profitable agriculture and subsequently improve livelihoods of farmers based on three main components, i.e. minimum or no tillage, retention of crop residues and use of crop rotation. However, to promote CA in semi-arid areas where precipitation is erratic, low, and falls over short periods in winter, its effects on soil and crop yield have to be investigated. The present study was conducted at the main research station of the International Center for Agricultural Research in the Dry Areas (ICARDA), Syria, during the agricultural season of 2010-2011, in the frame of a long term trial (2003-2011), where two treatments; i.e. conservation versus conventional agriculture (replicated twice), and six varieties of lentil (early, medium and late maturity genotypes; 2 each), selected from 100 varieties, were used. Soil samples were taken (before planting and after harvesting), to determine soil bulk density, particle density and total porosity. Aggregate stability was also determined using dry and wet sieving methods for the 0-15 cm soil depth, and the effective diameter of the aggregate was calculated for both treatments of conservation agriculture (CA) and conventional tillage (CT). Soil moisture was monitored in the top soil layer (0-15 cm) using Time Domain Reflectometry (TDR) on a weekly or two weekly-intervals. Soil moisture release curve was done for disturbed, 2 mm dry sieved soil at 0-15, 15-30, 30-45 and 45-60 cm depth using pressure plate chamber. Dry plant production (oven dry at 70°C) was estimated at the harvesting stage, and then threshed to estimate grain yield. CA showed higher (p = 0.001) soil moisture values than CT. The difference in volumetric soil moisture content between CA and CT during the studied period ranged from 20 to 30 %. Volumetric water content was higher for, CA compared with CT, at a given soil water potential especially at the lower pressure; this observation was consistent

  11. [Cutaneous Melanoma (CM): Current Diagnosis and Treatment].

    PubMed

    Gallegos Hernández, José Francisco; Nieweg, Omgo E

    2014-12-01

    Cutaneous melanoma (CM) is the third most common cancer of the skin, but it is the neoplasia with the greatest impact on mortality. Its etiology is multifactorial and it has been reported that its prevalence has increased in the last two decades. In Mexico, CM ranks seventh in frequency among all malignancies and 80% of cases are in locally advanced stages. The prognosis depends on the stage. The prognostic factors with greatest impact in survival are nodal status, tumor thickness or Breslow depth, ulceration, and in thin melanomas (< 1 mm thickness, without ulceration and Clarck level III), the mitotic index. The diagnostic approach is of great importance to achieve adequate treatment. Adherence to global guidelines of treatment allows us to obtain the best rates of locoregional control, which is the first target to be achieved in patients with CM. The goal of this manuscript is to provide a synthesis of the most important aspects in the diagnosis and treatment of CM, based on current evidence obtained in the literature.

  12. Neutron Resonance Parameters for Cm-242 (Curium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Cm-242 (Curium).

  13. Anomalous RR Lyrae stars(?): CM Leonis

    NASA Astrophysics Data System (ADS)

    Di Fabrizio, L.; Clementini, G.; Marconi, M.; Carretta, E.; Ivans, I. I.; Bragaglia, A.; Di Tomaso, S.; Merighi, R.; Smith, H. A.; Sneden, C.; Tosi, M.

    2002-11-01

    Time-series of B, V, I CCD photometry and radial velocity measurements from high-resolution spectroscopy (R= 30 000) covering the full pulsation cycle are presented for the field RR Lyrae star CM Leonis. The photometric data span a 6-yr interval from 1994 to 1999, and allow us to firmly establish the pulsation mode and periodicity of the variable. The derived period P= 0.361 699 d (+/-0.000001) is very close to the value published in the Fourth Edition of the General Catalogue of Variable Stars (P= 0.361 732 d). However, contrary to what was previously found, the amplitude and shape of the light curve qualify CM Leo as a very regular first overtone pulsator with a prominent hump on the rising branch of its multicolour light curves. According to an abundace analysis performed on three spectra taken near minimum light (0.42 < φ < 0.61), CM Leo is a metal-poor star with metal abundance [Fe/H]=-1.93 +/- 0.20. The photometric and radial velocity curves of CM Leo have been compared with the predictions of suitable pulsational models to infer tight constraints on the stellar mass, effective temperature, and distance modulus of the star. We derive a true distance modulus of CM Leo of μ0= 13.11 +/- 0.02 mag and a corresponding absolute magnitude of MV= 0.47 +/- 0.04. This absolute magnitude, once corrected for evolutionary and metallicity effects, leads to a true distance modulus of the Large Magellanic Cloud of μ0= 18.43 +/- 0.06 mag, in better agreement with the long astronomical distance scale.

  14. Towards the 1-cm SARAL orbit

    NASA Astrophysics Data System (ADS)

    Zelensky, Nikita P.; Lemoine, Frank G.; Chinn, Douglas S.; Beckley, Brian D.; Bordyugov, Oleg; Yang, Xu; Wimert, Jesse; Pavlis, Despina

    2016-12-01

    We have investigated the quality of precise orbits for the SARAL altimeter satellite using Satellite Laser Ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) data from March 14, 2013 to August 10, 2014. We have identified a 4.31 ± 0.14 cm error in the Z (cross-track) direction that defines the center-of-mass of the SARAL satellite in the spacecraft coordinate system, and we have tuned the SLR and DORIS tracking point offsets. After these changes, we reduce the average RMS of the SLR residuals for seven-day arcs from 1.85 to 1.38 cm. We tuned the non-conservative force model for SARAL, reducing the amplitude of the daily adjusted empirical accelerations by eight percent. We find that the best dynamic orbits show altimeter crossover residuals of 5.524 cm over cycles 7-15. Our analysis offers a unique illustration that high-elevation SLR residuals will not necessarily provide an accurate estimate of radial error at the 1-cm level, and that other supporting orbit tests are necessary for a better estimate. Through the application of improved models for handling time-variable gravity, the use of reduced-dynamic orbits, and through an arc-by-arc estimation of the C22 and S22 coefficients, we find from analysis of independent SLR residuals and other tests that we achieve 1.1-1.2 cm radial orbit accuracies for SARAL. The limiting errors stem from the inadequacy of the DPOD2008 and SLRF2008 station complements, and inadequacies in radiation force modeling, especially with respect to spacecraft self-shadowing and modeling of thermal variations due to eclipses.

  15. Potential risks of copper, zinc, and cadmium pollution due to pig manure application in a soil-rice system under intensive farming: a case study of Nanhu, China.

    PubMed

    Shi, Jiachun; Yu, Xiulin; Zhang, Mingkui; Lu, Shenggao; Wu, Weihong; Wu, Jianjun; Xu, Jianming

    2011-01-01

    Heavy metal (copper [Cu], zinc [Zn], and cadmium [Cd]) pollution of soils from pig manures in soil-rice ( L.) systems under intensive farming was investigated, taking Nanhu, China, as the case study area. Two hundred pig manures and 154 rice straws, brown rice samples, and corresponding surface soil (0-15 cm) samples were collected in paddy fields from 150 farms in 16 major villages within the study area. The mean Cu and Zn concentrations in pig manures consistently exceeded the related standard. About 44 and 60% of soil samples exceed the Chinese Soil Cu and Cd Environmental Quality Standards, respectively. The concentration of Cu, Zn, and Cd in brown rice did not exceed the Chinese Food Hygiene Standard. There was a significant positive correlation between total Cu and Zn contents in soil and application rate of pig manures. Strong correlation was observed between the extractable Cu, Zn, and Cd in soil and the Cu, Zn, and Cd contents in the brown rice. The spatial distribution maps of Cu and Zn concentrations in brown rice, straw, and extractable soil Cu and Zn concentration also showed similar geographical trends. Further analyses on heavy metals loading flux and accumulation rates from pig manure applied suggested that Cu and Cd contents in soil currently have already exceeded the maximum permissible limit, and Zn, if still at current manure application rates, will reach the ceiling concentration limits in 9 yr. This study assists in understanding the risk of heavy metals accumulating from pig manure applications to agricultural soils.

  16. The Destabilization of Protected Soil Organic Carbon Following Experimental Drought at the Pore and Core scale

    NASA Astrophysics Data System (ADS)

    Smith, A. P.; Bond-Lamberty, B. P.; Tfaily, M. M.; Todd-Brown, K. E.; Bailey, V. L.

    2015-12-01

    The movement of water and solutes through the pore matrix controls the distribution and transformation of carbon (C) in soils. Thus, a change in the hydrologic connectivity, such as increased saturation, disturbance or drought, may alter C mineralization and greenhouse gas (GHG) fluxes to the atmosphere. While these processes occur at the pore scale, they are often investigated at coarser scale. This project investigates pore- and core-scale soil C dynamics with varying hydrologic factors (simulated precipitation, groundwater-led saturation, and drought) to assess how climate-change induced shifts in hydrologic connectivity influences the destabilization of protected C in soils. Surface soil cores (0-15 cm depth) were collected from the Disney Wilderness Preserve, Florida, USA where water dynamics, particularly water table rise and fall, appear to exert a strong control on the emissions of GHGs and the persistence of soil organic matter in these soils. We measured CO2 and CH4 from soils allowed to freely imbibe water from below to a steady state starting from either field moist conditions or following experimental drought. Parallel treatments included the addition of similar quantities of water from above to simulate precipitation. Overall respiration increased in soil cores subjected to drought compared to field moist cores independent of wetting type. Cumulative CH4 production was higher in drought-induced soils, especially in the soils subjected to experimental groundwater-led saturation. Overall, the more C (from CO2 and CH4) was lost in drought-induced soils compared to field moist cores. Our results indicate that future drought events could have profound effects on the destabilization of protected C, especially in groundwater-fed soils. Our next steps focus on how to accurately capture drought-induced C destabilization mechanisms in earth system models.

  17. Magneto-transport characteristics of electron-doped Ca0.85Sm0.15MnO3 manganite: Hopping and tunneling

    NASA Astrophysics Data System (ADS)

    Hossain Khan, Momin; Pal, Sudipta

    2015-11-01

    In this work we have reported the temperature and magnetic field dependence of resistivity and magnetoresistance in electron-doped polycrystalline Ca0.85Sm0.15MnO3 (CSMO). It shows a robust semiconducting behavior down to the lowest temperature (5 K) of investigation. High-T resistivity of the present sample follows small polaron hopping (SPH) conduction mechanism. The variable range hopping (VRH) model has been found to fit low-T resistivity data. Intermediate-temperature ρ(T) data has been explained using a parallel combination of SPH and 3D-VRH model. The resistivity shows strong dependence on the magnetic field-temperature history. Magnetoresistance (MR) of the sample shows strong irreversibility with respect to sweeping of the field between the highest positive and negative values. Low-ρ state of the envelope curve in MR indicates a manifestation of kinetic arrest of the electronic phase on application of magnetic field. We demonstrates that the sizable MR at low fields dominated by spin-polarized tunneling between the adjacent grains.

  18. Re-construction layer effect of LiNi0.8Co0.15Mn0.05O2 with solvent evaporation process.

    PubMed

    Park, Kwangjin; Park, Jun-Ho; Hong, Suk-Gi; Choi, Byungjin; Heo, Sung; Seo, Seung-Woo; Min, Kyoungmin; Park, Jin-Hwan

    2017-03-20

    The solvent evaporation method on the structural changes and surface chemistry of the cathode and the effect of electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. After dissolving of Li residuals using minimum content of solvent in order to minimize the damage of pristine material and the evaporation time, the solvent was evaporated without filtering and remaining powder was re-heated at 700 °C in oxygen environment. Two kinds of solvent, de-ionized water and diluted nitric acid, were used as a solvent. The almost 40% of Li residuals were removed using solvent evaporation method. The NCM sample after solvent evaporation process exhibited an increase in the initial capacity (214.3 mAh/g) compared to the pristine sample (207.4 mAh/g) at 0.1C because of enhancement of electric conductivity caused by decline of Li residuals. The capacity retention of NCM sample after solvent evaporation process (96.0% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). The uniform Li residual layer after solvent treated and heat treatment acted like a coating layer, leading to enhance the cycle performance. The NCM sample using diluted nitric acid showed better performance than that using de-ionized water.

  19. Characterization and improvement of field CD uniformity for implementation of 0.15-μm technology device using KrF stepper

    NASA Astrophysics Data System (ADS)

    Hyun, Yoon-Suk; Kim, Dong-Joo; Koh, Cha-Won; Park, Sung-Nam; Kwon, Won-Taik

    2003-06-01

    xAs the design rule of semiconductor device shrinks, the field CD uniformity gets more important. For mass production of 0.15 μm technology device using KrF stepper having 0.63NA, the improvement of field CD uniformity was one of key issues because field CD uniformity is directly related to device characteristics in some layers. We have experienced steppers that show poor illumination uniformity. With those steppers there was large CD difference of about 10nm between field center and field edges as shown in Figure 1. Although we were using verified reticles, we could not get an acceptable CD uniformity in a field with those steppers. The Field CD uniformity is dominantly dependent of the illumination uniformity of stepper and mask quality. With these optimization, we could control DICD difference between field center and edge to be less than 5nm. In this paper, we characterized the dependency of field CD uniformity according to illumination systems with stepper and scanner, annular illumination uniformity at various stigma, mask CD uniformity and the several types of novel gray filter specifically developed.

  20. 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.

  1. 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.

  2. Microstructures of YBa1.85Eu0.15Cu3O7-δ superconducting films grown on SrTiO3 and YSZ substrates

    NASA Astrophysics Data System (ADS)

    Xie, Qiyun; Gu, Mingqiang; Qian, Bin; Wu, Xiaoshan; Jiang, Zhengsheng; Zou, Jin; Gao, Ju

    2011-03-01

    A detailed atomic scale microstructure analysis of Eu-doped YBa1.85Eu0.15Cu3O7-δ (YEBCO) thin films with 100 nm in thickness has been carried out by a combination of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Interesting regular-like arranged network of nanoscale undulations is observed on the surface of YEBCO film on (0 0 1) SrTiO3 substrate. TEM image clearly indicates that the film is always c-axis oriented, but lots of natural precipitates of Y2O3 are involved both at the interface and deep in the film. Desirable size and number density of Y2O3 are thought to be important for acting as efficient flux pinning centers. In the case of YEBCO film on (0 0 1) yttrium stabilized ZrO2 (YSZ) substrate, few cracks and outgrowths appear due to much larger lattice mismatch and dissimilar crystal structure between the film and substrate, but surface quality is still much better compared to the parent YBaCu3O7-δ film. Besides, highly textured BaZrO3 layer at the interface and a-axis grains with small dimensions in the film are formed. Interface stability of two kinds of films studied, namely YEBCO/STO and YEBCO/YSZ, is also assessed comprehensively by first principle calculations.

  3. Tuning the Activity of Oxygen in LiNi0.8Co0.15Al0.05O2 Battery Electrodes.

    PubMed

    Karki, Khim; Huang, Yiqing; Hwang, Sooyeon; Gamalski, Andrew D; Whittingham, M Stanley; Zhou, Guangwen; Stach, Eric A

    2016-10-06

    Layered transition metal oxides such as LiNi0.8Co 0.15Al0.05O2 (NCA) are highly desirable battery electrodes. However, these materials suffer from thermal runaway caused by deleterious oxygen loss and surface phase transitions when in highly overcharged and overheated conditions, prompting serious safety concerns. Using in situ environmental transmission electron microscopy techniques, we demonstrate that surface oxygen loss and structural changes in the highly overcharged NCA particles are suppressed by exposing them to an oxygen-rich environment. The onset temperature for the loss of oxygen from the electrode particle is delayed to 350 °C at oxygen gas overpressure of 400 mTorr. Similar heating of the particles in a reducing hydrogen gas demonstrated a quick onset of oxygen loss at 150 °C and rapid surface degradation of the particles. The results reported here illustrate the fundamental mechanism governing the failure processes of electrode particles and highlight possible strategies to circumvent such issues.

  4. Structural, magnetic and electrical transport properties in electron-doped La0.85Hf0.15MnO3 epitaxial film

    NASA Astrophysics Data System (ADS)

    Han, Li-an; Ma, Zi-wei; Zhu, Hua-ze; Chen, Chang-le; Zhang, Tao

    2017-03-01

    Using a pulsed laser deposition method, the electron-doped La0.85Hf0.15MnO3 (LHMO) film with the thickness of 90 nm was epitaxially grown on LaAlO3 (001) single crystal substrate. The structural, magnetic and electrical transport properties of the film have been studied comprehensively. The X-ray diffraction patterns confirm that LHMO film is of single phase, good quality and c axis orientation. The film undergoes a ferromagnetic-like ordering to paramagnetic states at T C =280 K. Moreover, a spin glass behavior observed in the film may be attributed to the strain effects. Using the percolation theory, we have analyzed the resistivity data ρ (T) of the film and given an excellent fit in the whole temperature range. Particularly, large temperature coefficient of resistance of 11.27% K- 1 has been discovered near sub-room-temperature, indicating that LHMO film could be useful for bolometric applications.

  5. A 50 MHz-1 GHz high linearity CATV amplifier with a 0.15 μm InGaAs PHEMT process

    NASA Astrophysics Data System (ADS)

    Jian, Xu; Zhigong, Wang; Ying, Zhang; Jing, Huang

    2011-07-01

    A 50 MHz-1 GHz low noise and high linearity amplifier monolithic-microwave integrated-circuit (MMIC) for cable TV is presented. A shunt AC voltage negative feedback combined with source current negative feedback is adopted to extend the bandwidth and linearity. A novel DC bias feedback is introduced to stabilize the operation point, which improved the linearity further. The circuit was fabricated with a 0.15 μm InGaAs PHEMT (pseudomorphic high electron mobility transistor) process. The test was carried out in 75 Ω systems from 50 MHz to 1 GHz. The measurement results showed that it gave a small signal gain of 16.5 dB with little gain ripples of less than ± 1 dB. An excellent noise figure of 1.7-2.9 dB is obtained in the designed band. The IIP3 is 16 dBm, which shows very good linearity. The CSO and CTB are high up to 68 dBc and 77 dBc, respectively. The chip area is 0.56 mm2 and the power dissipation is 110 mA with a 5 V supply. It is ideally suited to cable TV systems.

  6. 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.

  7. Solvent-Based Synthesis of Nano-Bi0.85Sb0.15 for Low-Temperature Thermoelectric Applications

    NASA Astrophysics Data System (ADS)

    Kaspar, K.; Fritsch, K.; Habicht, K.; Willenberg, B.; Hillebrecht, H.

    2017-01-01

    In this study we show a preparation method for nanostructured Bi0.85Sb0.15 powders via a chemical reduction route in a polyol medium, yielding material with particle sizes of 20-150 nm in scalable amounts. The powders were consolidated by spark plasma sintering (SPS) in order to maintain the nanostructure. To investigate influence of the sinter process, the powders were characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), and scanning electron microscopy (SEM) measurements before and after SPS. Transport properties, Seebeck effect, and thermal conductivity were determined in the low temperature range below 300 K. The samples showed excellent thermal conductivity of 2.3-2.6 W/m × K at 300 K and Seebeck coefficients from -97 μV/K to -107 μV/K at 300 K with a maximum of -141 μV/K at 110 K, thus leading to ZT values of up to 0.31 at room temperature. The results show that Bi-Sb-alloys are promising materials for low-temperature applications. Our wet chemical approach gives access to scalable amounts of nano-material with increased homogeneity and good thermoelectric properties after SPS.

  8. On the transport properties of the solid solution Sr 1- xLa xPbO 3- δ (0 ⩽ x ⩽ 0.15)

    NASA Astrophysics Data System (ADS)

    Hadjarab, B.; Bassaid, S.; Bouguelia, A.; Trari, M.

    2006-06-01

    Mixed valencies system Sr 1- xLa xPbO 3- δ (0 ⩽ x ⩽ 0.15) has been prepared by solid state reaction at 900 °C. All solutions crystallize in a distorted perovskite structure and were carefully examined by chemical analysis and X-ray diffraction. The La 3+-substitution was checked via the linear dependence of lattice constants on x-value, i.e. Vegard’s law. The expansion of the unit cell volume involves a simultaneous increase of all the parameters. The magnetic susceptibilities are slightly temperature dependent, dominated by core diamagnetism giving an effective mass m∗ of ∼9. The transport properties were investigated from 300 K down to liquid helium. The resistivity was found to change markedly with the rate substitution x and the oxides behave as degenerate semi-conductors with very weak activation energies. The insulating-metal transition can thus be considered of Anderson type attributed to random potential as lanthanum is substituted for strontium. The electric balance comes also from departure of oxygen and would imply a simultaneous reduction Pb 4+/2+. The electron mobility is thermally activated with a temperature independent carrier concentration.

  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. Re-construction layer effect of LiNi0.8Co0.15Mn0.05O2 with solvent evaporation process

    PubMed Central

    Park, Kwangjin; Park, Jun-Ho; Hong, Suk-Gi; Choi, Byungjin; Heo, Sung; Seo, Seung-Woo; Min, Kyoungmin; Park, Jin-Hwan

    2017-01-01

    The solvent evaporation method on the structural changes and surface chemistry of the cathode and the effect of electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. After dissolving of Li residuals using minimum content of solvent in order to minimize the damage of pristine material and the evaporation time, the solvent was evaporated without filtering and remaining powder was re-heated at 700 °C in oxygen environment. Two kinds of solvent, de-ionized water and diluted nitric acid, were used as a solvent. The almost 40% of Li residuals were removed using solvent evaporation method. The NCM sample after solvent evaporation process exhibited an increase in the initial capacity (214.3 mAh/g) compared to the pristine sample (207.4 mAh/g) at 0.1C because of enhancement of electric conductivity caused by decline of Li residuals. The capacity retention of NCM sample after solvent evaporation process (96.0% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). The uniform Li residual layer after solvent treated and heat treatment acted like a coating layer, leading to enhance the cycle performance. The NCM sample using diluted nitric acid showed better performance than that using de-ionized water. PMID:28317913

  11. Thermoelectric performance of n-type (PbTe)0.75(PbS)0.15(PbSe)0.1 composites.

    PubMed

    Yamini, Sima Aminorroaya; Wang, Heng; Ginting, Dianta; Mitchell, David R G; Dou, Shi Xue; Snyder, G Jeffrey

    2014-07-23

    Lead chalcogenides (PbQ, Q = Te, Se, S) have proved to possess high thermoelectric efficiency for both n-type and p-type compounds. Recent success in tuning of electronic band structure, including manipulating the band gap, multiple bands, or introducing resonant states, has led to a significant improvement in the thermoelectric performance of p-type lead chalcogenides compared to the n-type ones. Here, the n-type quaternary composites of (PbTe)0.75(PbS)0.15(PbSe)0.1 are studied to evaluate the effects of nanostructuring on lattice thermal conductivity, carrier mobility, and effective mass variation. The results are compared with the similar ternary systems of (PbTe)(1-x)(PbSe)x, (PbSe)(1-x)(PbS)x, and (PbS)(1-x)(PbTe)x. The reduction in the lattice thermal conductivity owing to phonon scattering at the defects and interfaces was found to be compensated by reduced carrier mobility. This results in a maximum figure of merit, zT, of ∼1.1 at 800 K similar to the performance of the single phase alloys of PbTe, PbSe, and (PbTe)(1-x)(PbSe)x.

  12. 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.

  13. 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.

  14. A large Hα survey of star formation in relaxed and merging galaxy cluster environments at z ∼ 0.15-0.3

    NASA Astrophysics Data System (ADS)

    Stroe, Andra; Sobral, David; Paulino-Afonso, Ana; Alegre, Lara; Calhau, João; Santos, Sergio; van Weeren, Reinout

    2017-03-01

    We present the first results from the largest Hα survey of star formation and active galactic nucleus activity in galaxy clusters. Using nine different narrow-band filters, we select >3000 Hα emitters within 19 clusters and their larger scale environment over a total volume of 1.3 × 105 Mpc3. The sample includes both relaxed and merging clusters, covering the 0.15-0.31 redshift range and spanning from 5 × 1014 to 30 × 1014 M⊙. We find that the Hα luminosity function for merging clusters has a higher characteristic density ϕ* compared to relaxed clusters. ϕ* drops from cluster core to cluster outskirts for both merging and relaxed clusters, with the merging cluster values ∼0.3 dex higher at each projected radius. The characteristic luminosity L* drops over the 0.5-2.0 Mpc distance from the cluster centre for merging clusters and increases for relaxed objects. Among disturbed objects, clusters hosting large-scale shock waves (traced by radio relics) are overdense in Hα emitters compared to those with turbulence in their intracluster medium (traced by radio haloes). We speculate that the increase in star formation activity in disturbed, young, massive galaxy clusters can be triggered by interactions between gas-rich galaxies, shocks and/or the intracluster medium, as well as accretion of filaments and galaxy groups. Our results indicate that disturbed clusters represent vastly different environments for galaxy evolution compared to relaxed clusters or average field environments.

  15. Re-construction layer effect of LiNi0.8Co0.15Mn0.05O2 with solvent evaporation process

    NASA Astrophysics Data System (ADS)

    Park, Kwangjin; Park, Jun-Ho; Hong, Suk-Gi; Choi, Byungjin; Heo, Sung; Seo, Seung-Woo; Min, Kyoungmin; Park, Jin-Hwan

    2017-03-01

    The solvent evaporation method on the structural changes and surface chemistry of the cathode and the effect of electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. After dissolving of Li residuals using minimum content of solvent in order to minimize the damage of pristine material and the evaporation time, the solvent was evaporated without filtering and remaining powder was re-heated at 700 °C in oxygen environment. Two kinds of solvent, de-ionized water and diluted nitric acid, were used as a solvent. The almost 40% of Li residuals were removed using solvent evaporation method. The NCM sample after solvent evaporation process exhibited an increase in the initial capacity (214.3 mAh/g) compared to the pristine sample (207.4 mAh/g) at 0.1C because of enhancement of electric conductivity caused by decline of Li residuals. The capacity retention of NCM sample after solvent evaporation process (96.0% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). The uniform Li residual layer after solvent treated and heat treatment acted like a coating layer, leading to enhance the cycle performance. The NCM sample using diluted nitric acid showed better performance than that using de-ionized water.

  16. Distribution of Cd, Ni, Cr and Pb in sewage sludge amended soils

    NASA Astrophysics Data System (ADS)

    Sanfeliu, Teófilo

    2010-05-01

    Restoration of degraded soils with organic wastes could be a feasible practice to minimise erosion in the Mediterranean area. Today the use of sewage sludge to improve the nutrient contents of a soil is a common practice. Contamination of soils by potentially toxic elements (e.g. Cd, Ni, Cr, Pb) from amendments of sewage sludge is subject to strict controls within the European Community in relation to total permissible metal concentrations, soil properties and intended use. This study is aimed at ascertaining the chemical partitioning of Cd, Ni, Cr and Pb in agricultural soils repeatedly amended with sludge. Five surface soils (0-15 cm) that were polluted as a result of agricultural activities were used in this experiment. The sewage sludge amended soils were selected for diversity of physicochemical properties, especially pH and carbonate content. The soils are classified as non-calcareous and calcareous soils. The distribution of chemical forms of Cd, Ni, Cr and Pb in five sewage sludge amended soils was studied using a sequential extraction procedure that fractionates the metal into soluble-exchangeable, specifically sorbed-carbonate bound, oxidizable, reducible and residual forms. With regard to the mineralogical composition of the soil clay fraction, the mineralogical association found was: illite, kaolinite and chlorite. This paper provides quantitative evidence regarding the form of the association of metals and indirectly of their bioavailability. It can help to explain the process by which metals are eliminated from sewage sludge and also indicate the impact of the use of sludge on agricultural soils, as amendments. Data obtained showed different metal distribution trend among the fractions in sludge-amended soils. Comparison of distribution pattern of metals in sludge-applied soils shows that there is possible redistribution of metals among the different phases. Detailed knowledge of the soil at the application site, especially pH, CEC, buffering capacity

  17. Measurements of Output Factors For Small Photon Fields Up to 10 cm x 10 cm

    NASA Astrophysics Data System (ADS)

    Bacala, Angelina

    Field output factors (OF) for photon beams from a 6 MV medical accelerator were measured using five different detectors in a scanning water phantom. The measurements were taken for square field sizes of integral widths ranging from 1 cm to 10 cm for two reference source-to-surface distances (SSD) and depths in water. For the diode detectors, square field widths as small as 2.5 mm were also studied. The photon beams were collimated by using either the jaws or the multileaf collimators. Measured OFs are found to depend upon the field size, SSD, depth and also upon the type of beam collimation, size and type of detector used. For field sizes larger than 3 cm x 3 cm, the OF measurements agree to within 1% or less. The largest variation in OF occurs for jawsshaped field of size 1 cm x 1cm, where a difference of more than 18% is observed.

  18. Effects of shrub encroachment on soil organic carbon in global grasslands

    NASA Astrophysics Data System (ADS)

    Li, He; Shen, Haihua; Chen, Leiyi; Liu, Taoyu; Hu, Huifeng; Zhao, Xia; Zhou, Luhong; Zhang, Pujin; Fang, Jingyun

    2016-07-01

    This study aimed to evaluate the effect of shrub encroachment on soil organic carbon (SOC) content at broad scales and its controls. We conducted a meta-analysis using paired control data of shrub-encroached grassland (SEG) vs. non-SEG collected from 142 studies worldwide. SOC contents (0–50 cm) were altered by shrub encroachment, with changes ranging from ‑50% to + 300%, with an effect size of 0.15 (p < 0.01). The SOC contents increased in semi-arid and humid regions, and showed a greater rate of increase in grassland encroached by leguminous shrubs than by non-legumes. The SOC content decreased in silty and clay soils but increased in sand, sandy loam and sandy clay loam. The SOC content increment was significantly positively correlated with precipitation and temperature as well as with soil bulk density but significantly negatively correlated with soil total nitrogen. We conclude the main effects of shrub encroachment would be to increase topsoil organic carbon content. As structural equation model revealed, soils properties seem to be the primary factors responsible for the extent of the changes, coarse textured soils having a greater capacity than fine textured soils to increase the SOC content. This increased effect appears to be secondarily enhanced by climate and plant elements.

  19. Effects of shrub encroachment on soil organic carbon in global grasslands

    PubMed Central

    Li, He; Shen, Haihua; Chen, Leiyi; Liu, Taoyu; Hu, Huifeng; Zhao, Xia; Zhou, Luhong; Zhang, Pujin; Fang, Jingyun

    2016-01-01

    This study aimed to evaluate the effect of shrub encroachment on soil organic carbon (SOC) content at broad scales and its controls. We conducted a meta-analysis using paired control data of shrub-encroached grassland (SEG) vs. non-SEG collected from 142 studies worldwide. SOC contents (0–50 cm) were altered by shrub encroachment, with changes ranging from −50% to + 300%, with an effect size of 0.15 (p < 0.01). The SOC contents increased in semi-arid and humid regions, and showed a greater rate of increase in grassland encroached by leguminous shrubs than by non-legumes. The SOC content decreased in silty and clay soils but increased in sand, sandy loam and sandy clay loam. The SOC content increment was significantly positively correlated with precipitation and temperature as well as with soil bulk density but significantly negatively correlated with soil total nitrogen. We conclude the main effects of shrub encroachment would be to increase topsoil organic carbon content. As structural equation model revealed, soils properties seem to be the primary factors responsible for the extent of the changes, coarse textured soils having a greater capacity than fine textured soils to increase the SOC content. This increased effect appears to be secondarily enhanced by climate and plant elements. PMID:27388145

  20. Interpreting Sky-Averaged 21-cm Measurements

    NASA Astrophysics Data System (ADS)

    Mirocha, Jordan

    2015-01-01

    Within the first ~billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this epoch of reionization -- the emergence of the first stars, black holes (BHs), and full-fledged galaxies -- are expected to manifest themselves as extrema in sky-averaged ("global") measurements of the redshifted 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) modeling required to make robust predictions.I have developed numerical models that efficiently solve the frequency-dependent radiative transfer equation, which has led to two advances in studies of the global 21-cm signal. First, frequency-dependent solutions facilitate studies of how the global 21-cm signal may be used to constrain the detailed spectral properties of the first stars, BHs, and galaxies, rather than just the timing of their formation. And second, the speed of these calculations allows one to search vast expanses of a currently unconstrained parameter space, while simultaneously characterizing the degeneracies between parameters of interest. I find principally that (1) physical properties of the IGM, such as its temperature and ionization state, can be constrained robustly from observations of the global 21-cm signal without invoking models for the astrophysical sources themselves, (2) translating IGM properties to galaxy properties is challenging, in large part due to frequency-dependent effects. For instance, evolution in the characteristic spectrum of accreting BHs can modify the 21-cm absorption signal at levels accessible to first generation instruments, but could easily be confused with evolution in the X-ray luminosity star-formation rate relation. Finally, (3) the independent constraints most likely to aide in the interpretation

  1. Total petroleum hydrocarbon distribution in soils and groundwater in Songyuan oilfield, Northeast China.

    PubMed

    Teng, Yanguo; Feng, Dan; Song, Liuting; Wang, Jinsheng; Li, Jian

    2013-11-01

    In order to investigate the distribution of the total petroleum hydrocarbons (TPH) in groundwater and soil, a total of 71 groundwater samples (26 unconfined groundwater samples, 37 confined groundwater samples, and 8 deeper confined groundwater samples) and 80 soil samples were collected in the Songyuan oilfield, Northeast China, and the vertical variation and spatial variability of TPH in groundwater and soil were assessed. For the groundwater from the unconfined aquifer, petroleum hydrocarbons were not detected in three samples, and for the other 23 samples, concentrations were in the range 0.01-1.74 mg/l. In the groundwater from the confined aquifer, petroleum hydrocarbons were not detected in two samples, and in the other 35 samples, the concentrations were 0.04-0.82 mg/l. The TPH concentration in unconfined aquifer may be influenced by polluted surface water and polluted soil; for confined aquifer, the injection wells leakage and left open hole wells may be mainly responsible for the pollution. For soils, the concentrations of TPH varied with sampling depth and were 0-15 cm (average concentration, 0.63 mg/g), >40-55 cm (average concentration, 0.36 mg/g), >100-115 cm (average concentration, 0.29 mg/g), and >500-515 cm (average concentration, 0.26 mg/g). The results showed that oil spillage and losses were possibly the main sources of TPH in soil. The consequences concluded here suggested that counter measures such as remediation and long-term monitoring should be commenced in the near future, and effective measures should be taken to assure that the oilfields area would not be a threat to human health.

  2. Data Simulation for 21 cm Cosmology Experiments

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan

    2017-01-01

    21 cm cosmologists seek a measurement of the hyperfine line of neutral hydrogen from very high redshifts. While this signal has the potential to provide an unprecedented view into the early universe, it is also buried under exceedingly bright foreground emission. Over the last several years, 21 cm cosmology research has led to an improved understanding of how low frequency radio interferometers will affect the separation of cosmological signal from foregrounds. This talk will describe new efforts to incorporate this understanding into simulations of the most realistic data sets for the Precision Array for Probing the Epoch of Reionization (PAPER), the Murchison Widefield Array (MWA), and the Hydrogen Epoch of Reionization Array (HERA). These high fidelity simulations are essential for robust algorithm design and validation of early results from these experiments.

  3. Extended Performance 8-cm Mercury Ion Thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1981-01-01

    A slightly modified 8-cm Hg ion thruster demonstrated significant increase in performance. Thrust was increased by almost a factor of five over that of the baseline thruster. Thruster operation with various three grid ion optics configurations; thruster performance as a function of accelerator grid open area, cathode baffle, and cathode orifice size; and a life test of 614 hours at a beam current of 250 mA (17.5 mN thrust) are discussed. Highest thruster efficiency was obtained with the smallest open area accelerator grid. The benefits in efficiency from the low neutral loss grids were mitigated, however, by the limitation such grids place on attainable ion beam current densities. The thruster components suffered negligible weight losses during a life test, which indicated that operation of the 8-cm thruster at extended levels of thrust and power is possible with no significant loss of lifetime.

  4. 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.

  5. 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.

  6. 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.

  7. Suppression of superconductivity of Dy0.6Y0.4Rh3.85Ru0.15B4 in inclined magnetic fields

    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.

    2015-04-01

    The electrical resistance of polycrystalline Dy0.6Y0.4Rh3.85Ru0.15B4 is measured for the first time near the superconducting transition temperature (Tc1/2 ≈ 6.66 K) in various inclined magnetic fields (φ = 0, 45, and 90°) and plots are made of R(T) and the upper critical field in dimensionless units h*(t). These dependences exhibit strong anisotropy with respect to the transport current through a sample when the orientation of the magnetic field is changed from φ = 0 to 90°. This appears to be related to texturing of the polycrystals. An analysis of the R(T) and h*(t) curves shows that the magnetic field suppresses the superconducting state more strongly at φ = 45° than at the other angles of inclination. The h*(t) dependences are analyzed in terms of the Werthamer-Helfand-Hohenberg theory and the Maki parameter α and the spin-orbital scattering parameter λSO are estimated. It is shown that for φ = 0 and 90°, α = 0 and λSO = 0 and only the orbital contribution is observed, while for φ = 45°, α = 4.2 and λSO = 0 and there is a substantial increase in the relative contribution of spin paramagnetic effects. It is suggested that the character of the R(T) and h*(t) curves in inclined magnetic fields is influenced by the effect on the superconducting state of the internal magnetism of the dysprosium atoms, which depends on the inclination of the field.

  8. Mn-doping induced ferromagnetism and enhanced superconductivity in Bi4 -xMnxO4S3 (0.075 ≤x ≤0.15 )

    NASA Astrophysics Data System (ADS)

    Feng, Zhenjie; Yin, Xunqing; Cao, Yiming; Peng, Xianglian; Gao, Tian; Yu, Chuan; Chen, Jingzhe; Kang, Baojuan; Lu, Bo; Guo, Juan; Li, Qing; Tseng, Wei-Shiuan; Ma, Zhongquan; Jing, Chao; Cao, Shixun; Zhang, Jincang; Yeh, N.-C.

    2016-08-01

    We demonstrate that Mn doping in the layered sulfides Bi4O4S3 leads to stable Bi4-xMnxO4S3 compounds that exhibit both long-range ferromagnetism and enhanced superconductivity for 0.075 ≤x ≤0.15 , with a possible record superconducting transition temperature (Tc) ˜15 K among all BiS2-based superconductors. We conjecture that the coexistence of superconductivity and ferromagnetism may be attributed to Mn doping in the spacer Bi2O2 layers away from the superconducting BiS2 layers, whereas the enhancement of Tc may be due to excess electron transfer to BiS2 from the Mn4 +/Mn3 + substitutions in Bi2O2 . This notion is empirically corroborated by the increased electron-carrier densities upon Mn doping, and by further studies of the Bi4-xAxO4S3 compounds (A = Co, Ni; x =0.1 , 0.125), where the Tc values remain comparable to that of the undoped Bi4O4S3 system (˜4.5 K) due to lack of 4+ valences in either Co or Ni ions for excess electron transfer to the BiS2 layers. These findings therefore shed new light on feasible pathways to enhance the Tc values of BiS2-based superconductors, although complete elucidation of the interplay between superconductivity and ferromagnetism in these anisotropic layered compounds awaits the development of single crystalline materials for further investigation.

  9. [Soil nutrient accumulation and its affecting factors during vegetation succession in karst peak-cluster depressions of South China].

    PubMed

    Zhang, Wei; Wang, Ke-Lin; Liu, Su-Juan; Ye, Ying-Ying; Pan, Fu-Jing; He, Xu-Yang

    2013-07-01

    Taking the typical karst peak-cluster depressions in Huanjiang County of northwest Guangxi as the objects, and by using the method of replacing time with space, an analysis was made on the dynamic changes of top soil (0-15 cm) nutrients and their dominant controlling factors during the process of vegetation succession. With the positive succession of vegetation (herb-shrub-secondary forest-primary forest), the soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents increased significantly, with the soil SOC, TN, and TP increased from 29.1 g x kg(-1), 2.48 g x kg(-1), and 0.72 g x kg(-1) in herb community to 73.9 g x kg(-1), 8.10 g x kg(-1), and 1.6 g x kg(-1) in primary forest, respectively, which indicated that the positive succession of vegetation was helpful to the soil nutrient accumulation. The soil cation exchange capacity (CEC) had close relationships with the soil SOC and TN, being the primary controlling factor for the accumulation of the soil C and N. The litter P content, C/P ratio, and N/P ratio were the major factors controlling the P accumulation in the topsoil. The litters higher P content and N/P ratio and smaller C/P ratio were helpful for the P accumulation. Topographic indices (slope, aspect, and rock exposure ratio) had little effects on the soil nutrients.

  10. Isotopically constrained soil carbon and nitrogen budgets in a soybean field chronosequence in the Brazilian Amazon region

    NASA Astrophysics Data System (ADS)

    Figueira, Adelaine M. e. Silva; Davidson, Eric A.; Nagy, R. Chelsea; Riskin, Shelby H.; Martinelli, Luiz A.

    2016-10-01

    The impacts of large-scale conversion of cattle pastures to cropland on soil carbon (C) and nitrogen (N) stocks are poorly understood in the Amazon region. The objective of this research was to determine whether soybean cultivation on a previously deforested and pastured soil has changed C and N stocks and dynamics. We sampled a chronosequence of soybean fields in 2009 and again in 2013. We hypothesized that detecting statistically significant changes in total soil C and N stocks would be difficult but that fluxes of C and N through the soil would be sufficiently large to significantly decrease the stable isotope ratios of soil organic matter. We observed statistically significant decreases in the 13C and 15N enrichments and C:N ratio. When combined with estimates of crop biomass production, harvest yield, and biological nitrogen fixation, these measurements provided sufficient constraints for C and N budgets to infer modest rates of net change in soil N (+15 to +27 kg N ha-1 yr-1) and soil C (-0.15 to -0.30 Mg C ha-1 yr-1) in the top 10 cm of soil. These results indicate that this intensive soybean cropping system is having minimal impacts on N loss to the environment but likely is a small net source of C to the atmosphere.

  11. [Dynamics of soil inorganic nitrogen in middle mountain moist evergreen broadleaf forest under different disturbance intensities in Ailao Mountain].

    PubMed

    Li, Guicai; Han, Xingguo; Huang, Jianhui; Wamg, Changyao

    2003-08-01

    The effects of three different intensities of disturbance on soil NH4(+)-N and NO3(-).N contents were studied in three community types (primary Lithocarpus xylocarpus forest, secondary oak forest, and tea plantation, which represent three different intensities of disturbance). The results showed that the contents of inorganic nitrogen in soil (0-15 cm) of three community types had marked differences. Soil organic matter and total nitrogen decreased, while C/N ratio increased, with the increasing intensity of the disturbance. Simultaneously, the potential lose of NO3(-)-N increased. It suggested that the disturbance was not in favor of the retainment of soil fertility and the positive development of community succession. The soil organic matter, total nitrogen and C/N ratio were basically same at different spatial sites in same community, while the NO3(-)-N contents were obvious difference. This implied that soil NO3(-)-N content was less stable than NH4(+)-N. In addition, NH4(+)-N was the major component of the soil inorganic nitrogen, accounted for 95.5%-99.3% of the total content of soil inorganic nitrogen.

  12. 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

  13. Effects of land use changes on the dynamics of selected soil properties in the Northeast Wollega, Ethiopia

    NASA Astrophysics Data System (ADS)

    Adugna, A.; Abegaz, A.

    2015-10-01

    Land use change can have negative or positive effects on soil quality. Our objective was to assess the effects of land uses changes on the dynamics of selected soil physical and chemical properties. Soil samples were collected from three adjacent land uses, namely forestland, grazing land and cultivated land at 0-15 cm depth, and tested in National Soil Testing Center, Ministry of Agriculture of Ethiopia. Percentage changes of soil properties on cultivated and grazing land was computed and compared to forestland, and Analysis of variance (ANOVA) was used to test the significance of the changes. The results indicate that sand, silt, SOM, N, pH, CEC and Ca were the highest in forestlands. Mg was the highest in grazing land while clay, P and K were the highest in cultivated land. The percentage changes in sand, clay, SOM, pH, CEC, Ca and Mg were higher in cultivated land than the change in grazing land compared to forestland, except P. In terms of relationship between soil properties; SOM, N, CEC and Ca were strongly positively correlated with most of soil properties while P and silt have no significant relationship with any of other considered soil properties. Clay has negative correlation with all of soil properties. Generally, cultivated land has the least concentration of soil physical and chemical properties except clay and AP which suggest increasing degradation rate in soils of cultivated land. So as to increase SOM and other nutrients in the soil of cultivated land, integrated implementation of land management through compost, cover crops, manures, minimum tillage and crop rotation; and liming to increase soil pH are suggested.

  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. 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.

  16. 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.

  17. 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.

  18. Effects of sandy desertified land rehabilitation on soil carbon sequestration and aggregation in an arid region in China.

    PubMed

    Su, Yong Zhong; Wang, Xue Fen; Yang, Rong; Lee, Jaehoon

    2010-11-01

    The rehabilitation of sandy desertified land in semi-arid and arid regions has a great potential to increase carbon sequestration and improve soil quality. Our objective was to investigate the changes in the soil carbon pool and soil properties of surface soil (0-15 cm) under different types of rehabilitation management. Our study was done in the short-term (7 years) and long-term (32 years) desertification control sites in a marginal oasis of northwest China. The different management treatments were: (1) untreated shifting sand land as control; (2) sand-fixing shrubs with straw checkerboards; (3) poplar (Populus gansuensis) shelter forest; and (4) irrigated cropland after leveling sand dune. The results showed that the rehabilitation of severe sandy desertified land resulted in significant increases in soil organic C (SOC), inorganic C, and total N concentrations, as well as enhanced soil aggregation. Over a 7-year period of revegetation and cultivation, SOC concentration in the recovered shrub land, forest land and irrigated cropland increased by 4.1, 14.6 and 11.9 times compared to the control site (shifting sand land), and increased by 11.2, 17.0 and 23.0 times over the 32-year recovery period. Total N, labile C (KMnO(4)-oxidation C), C management index (CMI) and inorganic C (CaCO(3)-C) showed a similar increasing trend as SOC. The increased soil C and N was positively related to the accumulation of fine particle fractions. The accumulation of silt and clay, soil C and CaCO(3) enhanced the formation of aggregates, which was beneficial to mitigate wind erosion. The percentage of >0.25 mm dry aggregates increased from 18.0% in the control site to 20.0-87.2% in the recovery sites, and the mean weight diameter (MWD) of water-stable aggregates significantly increased, with a range of 0.09-0.30 mm at the recovery sites. Long-term irrigation and fertilization led to a greater soil C and N accumulation in cropland than in shrub and forest lands. The amount of soil C

  19. The Evolution of Star formation Activity in Cluster Galaxies over 0.15 < z < 1.5

    NASA Astrophysics Data System (ADS)

    Wagner, Cory R.; Courteau, Stéphane; Brodwin, Mark; Stanford, S. A.; Snyder, Gregory F.; Stern, Daniel

    2017-01-01

    We explore 7.5 billion years of evolution in the star formation activity of massive ({M}\\star > {10}10.1 {M}ȯ ) cluster galaxies using a sample of 25 clusters over 0.15< z< 1 from the Cluster Lensing And Supernova survey with Hubble and 11 clusters over 1< z< 1.5 from the IRAC Shallow Cluster Survey. Galaxy morphologies are determined visually using high-resolution Hubble Space Telescope images. Using the spectral energy distribution fitting code Code Investigating GALaxy Emission, we measure star formation rates, stellar masses, and 4000 Å break strengths. The latter are used to separate quiescent and star-forming galaxies (SFGs). From z∼ 1.3 to z∼ 0.2, the specific star formation rate (sSFR) of cluster SFGs and quiescent galaxies decreases by factors of three and four, respectively. Over the same redshift range, the sSFR of the entire cluster population declines by a factor of 11, from 0.48+/- 0.06 {{Gyr}}-1 to 0.043+/- 0.009 {{Gyr}}-1. This strong overall sSFR evolution is driven by the growth of the quiescent population over time; the fraction of quiescent cluster galaxies increases from {28}-19+8 % to {88}-4+5 % over z ∼ 1.3 to 0.2. The majority of the growth occurs at z≳ 0.9, where the quiescent fraction increases by 0.41. While the sSFR of the majority of star-forming cluster galaxies is at the level of the field, a small subset of cluster SFGs have low field-relative star formation activity, suggestive of long-timescale quenching. The large increase in the fraction of quiescent galaxies above z∼ 0.9, coupled with the field-level sSFRs of cluster SFGs, suggests that higher-redshift cluster galaxies are likely being quenched quickly. Assessing those timescales will require more accurate stellar population ages and star formation histories.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Vertical and horizontal soil CO2 transport and its exchanges with the atmosphere

    NASA Astrophysics Data System (ADS)

    Sánchez-Cañete, Enrique P.; Serrano-Ortíz, Penélope; Kowalski, Andrew S.; Curiel Yuste, Jorge; Domingo, Francisco; Oyonarte, Cecilio

    2015-04-01

    The CO2 efflux from soils to the atmosphere constitutes one of the major fluxes of the terrestrial carbon cycle and is a key determinant for sources and sinks of CO2 in land-atmosphere exchanges. Because of their large global magnitude, even small changes in soil CO2 effluxes directly affect the atmospheric CO2 content. Despite much research, models of soil CO2 efflux rates are highly uncertain, with the positive or negative feedbacks between underground carbon pools and fluxes and their temperature sensitivities in future climate scenarios largely unknown. Now it is necessary to change the point of view regarding CO2 exchange studies from an inappropriately conceived static system in which all respired CO2 is directly emitted by molecular processes to the atmosphere, to a dynamic system with gas transport by three different processes: convection, advection and molecular diffusion. Here we study the effects of wind-induced advection on the soil CO2 molar fraction during two years in a shrubland plateau situated in the Southeast of Spain. A borehole and two subterranean profiles (vertical and horizontal) were installed to study CO2 transport in the soil. Exchanges with the atmosphere were measured by an eddy covariance tower. In the vertical profile, two CO2 sensors (GMP-343, Vaisala) were installed at 0.15m and 1.5m along with soil temperature and humidity probes. The horizontal profile was designed to measure horizontal movements in the soil CO2 molar fraction due to down-gradient CO2 from the plant, where the majority CO2 is produced, towards bare soil. Three CO2 sensors (GMM-222, Vaisala) were installed, the first below plant (under-plant), the second in bare soil separated 25 cm from the first sensor (near-plant) and the third in bare soil at 25 cm from the second sensor (bare soil). The results show how the wind induces the movement of subterranean air masses both horizontally and vertically, affecting atmospheric CO2 exchanges. The eddy covariance tower

  6. Design study of large area 8 cm x 8 cm wrapthrough cells for space station

    NASA Technical Reports Server (NTRS)

    Garlick, George F. J.; Lillington, David R.

    1987-01-01

    The design of large area silicon solar cells for the projected NASA space station is discussed. It is based on the NASA specification for the cells which calls for an 8 cm by 8 cm cell of wrapthrough type with gridded back contacts. The beginning of life (BOL) power must be 1.039 watts per cell or larger and maximum end of life (EOL) after 10 years in the prescribed orbit under an equivalent 1MeV electron radiation damage fluence of 5 times 10 to the 13th power e/square cm. On orbit efficiency is to be optimized by a low thermal absorptance goal (thermal alpha) of .63.

  7. Aliphatic Amines in Antarctic CR2, CM2, and CM1/2 Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    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 delta13C 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 delta13C 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 delta13C values of methylamine in CR2 chondrites ranged from -1 to +10per mille, while in CM2 and CM1/2 chondrites the delta13C values of methylamine ranged from +41 to +59per mille. 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 delta13C 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.

  8. 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.

  9. Soil moisture decline across the conterminous United States

    NASA Astrophysics Data System (ADS)

    Guevara, M.; Vargas, R.

    2015-12-01

    Changes in soil moisture (SM) are directly related to food and environmental security around the world. Furthermore, precise information about temporal and spatial patterns of SM is crucial for realistic interpretations of environmental change and policy relevant research. This study shows how data fusion of topography (represented by a digital elevation models and derived terrain attributes) and annual SM (represented by remotely sensed microwave observations from 1978 to 2013) enhance spatial detail and improves the correlation between remotely sensed and ground truth SM observations. On average, topography explains 80% of remotely sensed soil moisture variability using a kernel-based form of regression with a RMSE of 0.026 via cross-validation. Predictions of annual SM were generated across the conterminous United States at 1km pixel size for the 36 years of available data. Previous studies report that SM remote sensing data, derived from microwave observations (~27km pixel size), is representative of the first 2 cm of soil depth. We found that field SM measurements best correlates with our 1 km SM product at 60 cm soil depth (R2= 0.52). Furthermore, by averaging field SM measurements between 25 and 60 cm the correlation improved to R2= 0.62. Our results show a similar negative temporal trend for field SM observations and our predicted SM product at 1km pixel size. For both cases the slope is showing a reduction of -1.87 (-0.64 -3.23) %/year and -0.92 (-0.15, -1.25) %/year, respectively. We found a consistent decline of SM at the national level, and a sharp decay in 2012 and 2013. The temporal variability of SM is partially (~51%) explained by spatial and temporal trends of precipitation and temperature across the United States. These results provide insights of alternative approaches to estimate SM trends across continental-to-global scales.

  10. Evaluation of Plant- Compost -Microorganisms Synergy for the Remediation of Diesel contaminated Soil: Success Stories from the Field Station

    NASA Astrophysics Data System (ADS)

    Hussain, Imran; Wimmer, Bernhard; Soja, Gerhard; Sessitsch, Angela; Reichenauer, Thomas G.

    2016-04-01

    Total petroleum hydrocarbons (TPH) contain a mixture of crude oil, gasoline, creosote and diesel is one of the most common groups of persistent organic pollutants. TPH enters into the ecosystem (soil, water and air) through leakage of underground storage tanks (LUST), accidental oil spills, transportation losses and industrial processes. Pollution associated with diesel oil and its refined products is of great concern worldwide due to its threats/damages for human and ecosystem health, soil structure and ground water quality. Extensive soils pollution with petroleum hydrocarbons results in extreme harsh surroundings, produce hydrophobic conditions and infertile soils that ultimately lead towards less plant and microorganisms growth. Among biological methods, bioremediation and phytoremediation are promising technologies that have both technical and ecological benefits as compared to convention methods. Within phytoremediation, rhizoremediation based on stimulation of degrading microorganism's population influenced by plant rhizospheric effect is known as main mechanism for phytoremediation of petroleum polluted soils. Composting along with rhizodegradtion was used to remediate freshly spilled soils at Lysimeter station Siebersdof, Austria. Experiment was started in July 2013 and will be monitored up to September 2016. Field station has 12 Lysimeter in total; each has length, width and depth of 100 cm respectively. Each Lysimeter was filled with normal agricultural soil from Siebersdof (0-70 cm), sand (70-85 cm) and stones (85-100cm). Sand and stones were added to support the normal leaching and percolation of water as we collected leachate samples after regular intervals. After filling, commercial diesel oil (2% w/w of 0-70 cm soil) was spilled on top of each Lysimeter as accidental spill occurs in filed. Compost was added at 0-15 cm layer (5% w/w of soil) to stimulate plant as well as microorganisms growth. Whole Lysimeter station was divided into three treatments

  11. 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.

  12. 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.

  13. Magnesium isotopic fractionation in chondrules from the Murchison and Murray CM2 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Bouvier, Audrey; Wadhwa, Meenakshi; Simon, Steven B.; Grossman, Lawrence

    2013-03-01

    We present high-precision measurements of the Mg isotopic compositions of a suite of types I and II chondrules separated from the Murchison and Murray CM2 carbonaceous chondrites. These chondrules are olivine- and pyroxene-rich and have low 27Al/24Mg ratios (0.012-0.316). The Mg isotopic compositions of Murray chondrules are on average lighter (δ26Mg ranging from -0.95‰ to -0.15‰ relative to the DSM-3 standard) than those of Murchison (δ26Mg ranging from -1.27‰ to +0.77‰). Taken together, the CM2 chondrules exhibit a narrower range of Mg isotopic compositions than those from CV and CB chondrites studied previously. The least-altered CM2 chondrules are on average lighter (average δ26Mg = -0.39 ± 0.30‰, 2SE) than the moderately to heavily altered CM2 chondrules (average δ26Mg = -0.11 ± 0.21‰, 2SE). The compositions of CM2 chondrules are consistent with isotopic fractionation toward heavy Mg being associated with the formation of secondary silicate phases on the CM2 parent body, but were also probably affected by volatilization and recondensation processes involved in their original formation. The low-Al CM2 chondrules analyzed here do not exhibit any mass-independent variations in 26Mg from the decay of 26Al, with the exception of two chondrules that show only small variations just outside of the analytical error. In the case of the chondrule with the highest Al/Mg ratio (a type IAB chondrule from Murchison), the lack of resolvable 26Mg excess suggests that it either formed >1 Ma after calcium-aluminum-rich inclusions, or that its Al-Mg isotope systematics were reset by secondary alteration processes on the CM2 chondrite parent body after the decay of 26Al.

  14. 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.

  15. Field study: Influence of fly ash on leachate composition in an excessively drained soil

    SciTech Connect

    Gangloff, W.J.; Sims, J.T.; Vasilas, B.L.; Ghodrati, M.

    1997-05-01

    Alternatives to landfilling fly ash may be to use it as a soil amendment since it is fine textured and could alter soil texture and thus improve water retention. However, fly ash contains elevated B, soluble salts, and trace element concentrations that could adversely affect plant and soil quality. Objectives were to characterize leaching of soluble salts, plant nutrients, and trace elements in a sandy soil amended with a high rate of fly ash ({approximately}662 Mg ha{sup -1}). We established Field plots in an Evesboro loamy sand using typical agricultural equipment. Lysimeters were installed to a depth of 120 cm and used to collect leachate over a 9 mo period. We also used microplots; (1.0 by 1.0 m) and similar ash rates to characterize leaching under controlled conditions. Lysimeters were installed at four depths in each microplot (15, 30, 60, and 120 cm) and water applied with a rainfall simulator. Boron and soluble salts were leached from the rooting zone after {approximately}38 cm of natural rainfall or 42 cm of irrigation. Calcium and S were the dominant plant macronutrients in leachates while Cu, Mn, and Zn were the only detectable micronutrients. Peak concentrations of these elements were detected after {approximately}50 cm of rainfall or irrigation and decreased to below or near initial concentrations by the conclusion of the study. Nickel was the only detectable trace element in leachates, however, concentrations were variable and <0.15 mg L{sup -1}. Results suggest that if fly ash incorporation is properly timed to allow for natural leaching, adverse effects will be minimal. 29 refs., 5 figs., 5 tabs.

  16. CARBON SEQUESTRATION IN RECLAIMED MINED SOILS OF OHIO

    SciTech Connect

    M.K. Shukla; R. Lal

    2004-10-01

    This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites, owned and maintained by the American Electrical Power, are located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites, characterized by age chronosequences, were reclaimed with and without topsoil application and are under continuous grass or forest cover. During this quarter, water infiltration tests were performed on the soil surface in the experimental sites. Soil samples were analyzed for the soil carbon and nitrogen contents, texture, water stable aggregation, and mean weight and geometric mean diameter of aggregates. This report presents the results from two sites reclaimed during 1978 and managed under grass (Wilds) and forest (Cumberland) cover, respectively. The trees were planted in 1982 in the Cumberland site. The analyses of data on soil bulk density ({rho}{sub b}), SOC and total nitrogen (TN) concentrations and stocks were presented in the third quarter report. This report presents the data on infiltration rates, volume of transport and storage pores, available water capacity (AWC) of soil, particle size distribution, and soil inorganic carbon (SIC) and coal carbon contents. The SIC content ranged from 0.04 to 1.68% in Cumberland tree site and 0.01 to 0.65% in the Wilds. The coal content assumed to be the carbon content after oven drying the sample at 350 C varied between 0.04 and 3.18% for Cumberland and 0.06 and 3.49% for Wilds. The sand, silt and clay contents showed moderate to low variability (CV < 0.16) for 0-15 and 15-30 cm depths. The volume of transmission (VTP) and storage pores (VSP) also showed moderate to high variability (CV ranged from 0.22 to 0.39 for Wilds and 0.17 to 0.36 for Cumberland). The CV for SIC was high (0.7) in Cumberland whereas that for coal content was high (0.4) in the Wilds. The steady state infiltration rates (i{sub c}) also showed high variability

  17. 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

  18. More New Carbon in the Soil of a Poplar Plantation Under Free Air Carbon Enrichment

    NASA Astrophysics Data System (ADS)

    Hoosbeek, M. R.

    2002-12-01

    Early 1999 three FACE (Free Air Carbon Enrichment) and three control rings were installed on former agricultural fields near Viterbo, Italy. A 9 ha poplar plantation was established using hardwood cuttings. Within the rings two Populus species and one hybrid were planted (P. nigra, P. alba, P.x euramericana) at a density of 10000 per ha. The 314 m2 circular plots were divided in six sectors, with two sectors per species. Carbon enrichment was achieved by injection of pure CO2 through laser drilled holes in tubing mounted on telescopic poles. The average CO2 concentration was 544 +/- 48 micromol mol-1. During the first year the total C content of the soils decreased on average from 1.05% to 0.95%. During the second and third year the total soil carbon content remained more or less stable, while no treatment effects could be detected due to the large C pool as compared to the annual C influx. The d13C signature of the CO2 enrichment gas was close to that of ambient CO2, and could therefore not be used as an isotopic signal to follow the incorporation of new carbon into the soil carbon pool. Instead we used root ingrowth cores (40 cm deep, 4 cm in diameter) filled with sieved and well mixed C4 soil. This C4 soil with a d13C value of -18.33 was obtained from a similar soil that had been under corn for many years. For each incubation period, species and rings, two ingrowth cores were placed in the C3 soil. Fractions of new carbon were calculated with a simple mixing model. Multiplying these fractions with the total C content yielded the new C contents (by weight percentage). During the first year no treatment effect was detected. During the second year, new soil C% under P. alba was respectively 0.12 under ambient and 0.15 under increased CO2 treatment (P= 0.07). The third year showed the same effect on new soil C%, i.e. with P. alba respectively 0.07 under ambient and 0.13 under increased CO2 treatment (P= 0.02), and with P. nigra respectively 0.08 under ambient and 0.15

  19. [Spatiotemporal heterogeneity and its formation causes of soil physical properties in karst peak-cluster depression area of northwest Guangxi, China].

    PubMed

    Liu, Shu-juan; Zhang, Wei; Wang, Ke-lin; Chen, Hong-song; Wei, Guo-fu

    2010-09-01

    Soil samples were collected from the grassland, shrub land, secondary forest, and original forest on the hill slope in a typical karst peak-cluster depression area of northwest Guanxi, with the spatiotemporal heterogeneity of soil physical properties investigated by classical statistics, and the formation causes of the heterogeneity analyzed by redundancy analysis (RDA). In 0-15 cm soil layer, the clay (< 0.002 mm) and silt (0.002-0.05 mm) contents of shrub land and original forest had significant differences with those of grassland and secondary forest, respectively, but the clay, silt, and sand (0.05-2.0 mm) contents had no significant differences between grassland and secondary forest. No significant difference was observed in the soil sand content among the four land types, but the soil bulk density of grassland was significantly different from that of other three land types. The soil clay content of grassland increased with increasing elevation, while that of the other three land types was the highest on medium slope, and had no significant differences for the same land types among different slope locations. The soil clay content in different layers of 0-30 cm had a greater variation extent in original forest (14.55%) than in grassland (7.12%), shrub land (11.24%), and secondary forest (13.77%), and the soil particle size composition was greatly affected by the disturbance of human activities. Soil organic carbon (SOC) and vegetation type were the dominant factors affecting the soil physical properties, and the bare rock ratio had greater effects on soil sand content.

  20. Microbial physiology and soil CO2 efflux after 9 years of soil warming in a temperate forest - no indications for thermal adaptations.

    PubMed

    Schindlbacher, Andreas; Schnecker, Jörg; Takriti, Mounir; Borken, Werner; Wanek, Wolfgang

    2015-11-01

    Thermal adaptations of soil microorganisms could mitigate or facilitate global warming effects on soil organic matter (SOM) decomposition and soil CO2 efflux. We incubated soil from warmed and control subplots of a forest soil warming experiment to assess whether 9 years of soil warming affected the rates and the temperature sensitivity of the soil CO2 efflux, extracellular enzyme activities, microbial efficiency, and gross N mineralization. Mineral soil (0-10 cm depth) was incubated at temperatures ranging from 3 to 23 °C. No adaptations to long-term warming were observed regarding the heterotrophic soil CO2 efflux (R10 warmed: 2.31 ± 0.15 μmol m(-2)  s(-1) , control: 2.34 ± 0.29 μmol m(-2)  s(-1) ; Q10 warmed: 2.45 ± 0.06, control: 2.45 ± 0.04). Potential enzyme activities increased with incubation temperature, but the temperature sensitivity of the enzymes did not differ between the warmed and the control soils. The ratio of C : N acquiring enzyme activities was significantly higher in the warmed soil. Microbial biomass-specific respiration rates increased with incubation temperature, but the rates and the temperature sensitivity (Q10 warmed: 2.54 ± 0.23, control 2.75 ± 0.17) did not differ between warmed and control soils. Microbial substrate use efficiency (SUE) declined with increasing incubation temperature in both, warmed and control, soils. SUE and its temperature sensitivity (Q10 warmed: 0.84 ± 0.03, control: 0.88 ± 0.01) did not differ between warmed and control soils either. Gross N mineralization was invariant to incubation temperature and was not affected by long-term soil warming. Our results indicate that thermal adaptations of the microbial decomposer community are unlikely to occur in C-rich calcareous temperate forest soils.

  1. Using isotopic tracers to assess the impact of tillage and straw management on the microbial metabolic network in soil

    NASA Astrophysics Data System (ADS)

    Van Groenigen, K.; Forristal, D.; Jones, M. B.; Schwartz, E.; Hungate, B. A.; Dijkstra, P.

    2013-12-01

    By decomposing soil organic matter, microbes gain energy and building blocks for biosynthesis and release CO2 to the atmosphere. Therefore, insight into the effect of management practices on microbial metabolic pathways and C use efficiency (CUE; microbial C produced per substrate C utilized) may help to predict long term changes in soil C stocks. We studied the effects of reduced (RT) and conventional tillage (CT) on the microbial central C metabolic network, using soil samples from a 12-year-old field experiment in an Irish winter wheat cropping system. Each year after harvest, straw was removed from half of the RT and CT plots or incorporated into the soil in the other half, resulting in four treatment combinations. We added 1-13C and 2,3-13C pyruvate and 1-13C and U-13C glucose as metabolic tracer isotopomers to composite soil samples taken at two depths (0-15 cm and 15-30 cm) from each treatment and used the rate of position-specific respired 13CO2 to parameterize a metabolic model. Model outcomes were then used to calculate CUE of the microbial community. We found that the composite samples differed in CUE, but the changes were small, with values ranging between 0.757-0.783 across treatments and soil depth. Increases in CUE were associated with a decrease in tricarboxylic acid cycle and reductive pentose phosphate pathway activity and increased consumption of metabolic intermediates for biosynthesis. Our results indicate that RT and straw incorporation promote soil C storage without substantially changing CUE or any of the microbial metabolic pathways. This suggests that at our site, RT and straw incorporation promote soil C storage mostly through direct effects such as increased soil C input and physical protection from decomposition, rather than by feedback responses of the microbial community.

  2. 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.

  3. 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.

  4. Effects of land use and land cover on selected soil quality indicators in the headwater area of the Blue Nile basin of Ethiopia.

    PubMed

    Teferi, Ermias; Bewket, Woldeamlak; Simane, Belay

    2016-02-01

    Understanding changes in soil quality resulting from land use and land management changes is important to design sustainable land management plans or interventions. This study evaluated the influence of land use and land cover (LULC) on key soil quality indicators (SQIs) within a small watershed (Jedeb) in the Blue Nile Basin of Ethiopia. Factor analysis based on principal component analysis (PCA) was used to determine different SQIs. Surface (0-15 cm) soil samples with four replications were collected from five main LULC types in the watershed (i.e., natural woody vegetation, plantation forest, grassland, cultivated land, and barren land) and at two elevation classes (upland and midland), and 13 soil properties were measured for each replicate. A factorial (2 × 5) multivariate analysis of variance (MANOVA) showed that LULC and altitude together significantly affected organic matter (OM) levels. However, LULC alone significantly affected bulk density and altitude alone significantly affected bulk density, soil acidity, and silt content. Afforestation of barren land with eucalypt trees can significantly increase the soil OM in the midland part but not in the upland part. Soils under grassland had a significantly higher bulk density than did soils under natural woody vegetation indicating that de-vegetation and conversion to grassland could lead to soil compaction. Thus, the historical LULC change in the Jedeb watershed has resulted in the loss of soil OM and increased soil compaction. The study shows that a land use and management system can be monitored if it degrades or maintains or improves the soil using key soil quality indicators.

  5. Initial characterization of processes of soil carbon stabilization using forest stand-level radiocarbon enrichment

    SciTech Connect

    Swanston, C W; Torn, M S; Hanson, P J; Southon, J R; Garten, C T; Hanlon, E M; Ganio, L

    2004-01-15

    Although the rates and mechanisms of soil organic matter (SOM) stabilization are difficult to observe directly, radiocarbon has proven an effective tracer of soil C dynamics, particularly when coupled with practical fractionation schemes. To explore the rates of C cycling in temperate forest soils, we took advantage of a unique opportunity in the form of an inadvertent stand-level {sup 14}C-labeling originating from a local industrial release. A simple density fractionation scheme separated SOM into inter-aggregate particulate organic matter (free light fraction, free LF), particulate organic matter occluded within aggregates (occluded LF), and organic matter that is complexed with minerals to form a dense fraction (dense fraction, DF). Minimal agitation and density separation was used to isolate the free LF. The remaining dense sediment was subjected to physical disruption and sonication followed by density separation to separate it into occluded LF and DF. The occluded LF had higher C concentrations and C:N ratios than the free LF, and the C concentration in both light fractions was ten times that of the DF. As a result, the light fractions together accounted for less than 4% of the soil by weight, but contained 40% of the soil C in the 0-15 cm soil increment. Likewise, the light fractions were less than 1% weight of the 15-30 cm increment, but contained more than 35% of the soil C. The degree of SOM protection in the fractions, as indicated by {Delta}{sup 14}C, was different. In all cases the free LF had the shortest mean residence times. A significant depth by fraction interaction for {sup 14}C indicates that the relative importance of aggregation versus organo-mineral interactions for overall C stabilization changes with depth. The rapid incorporation of {sup 14}C label into the otherwise depleted DF shows that this organo-mineral fraction comprises highly stable material as well as more recent inputs.

  6. Accuracy of free energies of hydration using CM1 and CM3 atomic charges.

    PubMed

    Udier-Blagović, Marina; Morales De Tirado, Patricia; Pearlman, Shoshannah A; Jorgensen, William L

    2004-08-01

    Absolute free energies of hydration (DeltaGhyd) have been computed for 25 diverse organic molecules using partial atomic charges derived from AM1 and PM3 wave functions via the CM1 and CM3 procedures of Cramer, Truhlar, and coworkers. Comparisons are made with results using charges fit to the electrostatic potential surface (EPS) from ab initio 6-31G* wave functions and from the OPLS-AA force field. OPLS Lennard-Jones parameters for the organic molecules were used together with the TIP4P water model in Monte Carlo simulations with free energy perturbation theory. Absolute free energies of hydration were computed for OPLS united-atom and all-atom methane by annihilating the solutes in water and in the gas phase, and absolute DeltaGhyd values for all other molecules were computed via transformation to one of these references. Optimal charge scaling factors were determined by minimizing the unsigned average error between experimental and calculated hydration free energies. The PM3-based charge models do not lead to lower average errors than obtained with the EPS charges for the subset of 13 molecules in the original study. However, improvement is obtained by scaling the CM1A partial charges by 1.14 and the CM3A charges by 1.15, which leads to average errors of 1.0 and 1.1 kcal/mol for the full set of 25 molecules. The scaled CM1A charges also yield the best results for the hydration of amides including the E/Z free-energy difference for N-methylacetamide in water.

  7. Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization.

    PubMed

    Kim, Han Sik; Jung, Myung Chae

    2012-01-01

    This survey aimed to compare mercury concentrations in soils related to geology and mineralization types of mines. A total of 16,386 surface soils (0~15 cm in depth) were taken from agricultural lands near 343 abandoned mines (within 2 km from each mine) and analyzed for Hg by AAS with a hydride-generation device. To meaningfully compare mercury levels in soils with geology and mineralization types, three subclassification criteria were adapted: (1) five mineralization types, (2) four valuable ore mineral types, and (3) four parent rock types. The average concentration of Hg in all soils was 0.204 mg kg(-1) with a range of 0.002-24.07 mg kg(-1). Based on the mineralization types, average Hg concentrations (mg kg(-1)) in the soils decreased in the order of pegmatite (0.250) > hydrothermal vein (0.208) > hydrothermal replacement (0.166) > skarn (0.121) > sedimentary deposits (0.045). In terms of the valuable ore mineral types, the concentrations decreased in the order of Au-Ag-base metal mines ≈ base metal mines > Au-Ag mines > Sn-W-Mo-Fe-Mn mines. For parent rock types, similar concentrations were found in the soils derived from sedimentary rocks and metamorphic rocks followed by heterogeneous rocks with igneous and metamorphic processes. Furthermore, farmland soils contained relatively higher Hg levels than paddy soils. Therefore, it can be concluded that soils in Au, Ag, and base metal mines derived from a hydrothermal vein type of metamorphic rocks and pegmatite deposits contained relatively higher concentrations of mercury in the surface environment.

  8. New λ6 cm and λ11 cm observations of the supernova remnant CTA 1

    NASA Astrophysics Data System (ADS)

    Sun, X. H.; Reich, W.; Wang, C.; Han, J. L.; Reich, P.

    2011-11-01

    Aims: We attempt to study spatial variations in the spectrum and rotation measures (RMs) of the large-diameter, high-latitude supernova remnant (SNR) CTA 1. Methods: We conducted new λ6 cm and λ11 cm observations of CTA 1 using the Urumqi 25-m and Effelsberg 100-m telescopes. Data at other wavelengths were included to investigate the spectrum and polarisation properties. Results: We obtained new total intensity and polarisation maps at λ6 cm and λ11 cm with angular resolutions of 9'.5and 4'.4, respectively. We derived a spectral index of α = -0.63 ± 0.05 (Sν ∝ να) based on the integrated flux densities at 408 MHz, 1420 MHz, 2639 MHz, and 4800 MHz. The spectral index map calculated from data at the four frequencies shows a clear steepening of the spectrum from the strong shell emission towards the north-western breakout region with weak diffuse emission. The decrease of the spectral index is up to about Δα = 0.3. The RM map derived from polarisation data at λ6 cm and λ11 cm shows a sharp transition between positive RMs in the north-eastern and negative RMs in the south-western part of the SNR. We note a corresponding RM pattern of extragalactic sources and propose the existence of a large-diameter Faraday screen in front of CTA 1, which covers the north-eastern part of the SNR. The RM of the Faraday screen is estimated to be about +45 rad m-2. A RM structure function of CTA 1 indicates a very regular magnetic field within the Faraday screen, which is stronger than about 2.7 μG for a distance of 500 pc. Conclusions: CTA 1 is a large-diameter shell-type SNR located out of the Galactic plane, which makes it an ideal object to study its properties without suffering confusion. The previous detection of the rare breakout phenomenon in CTA 1 is confirmed. We identify a Faraday screen partly covering CTA 1 with a regular magnetic field in the opposite direction to the interstellar magnetic field. The detection of Faraday screens in the Galactic plane is

  9. Spatial and temporal variability of soil moisture on the field with and without plants*

    NASA Astrophysics Data System (ADS)

    Usowicz, B.; Marczewski, W.; Usowicz, J. B.

    2012-04-01

    Spatial and temporal variability of the natural environment is its inherent and unavoidable feature. Every element of the environment is characterized by its own variability. One of the kinds of variability in the natural environment is the variability of the soil environment. To acquire better and deeper knowledge and understanding of the temporal and spatial variability of the physical, chemical and biological features of the soil environment, we should determine the causes that induce a given variability. Relatively stable features of soil include its texture and mineral composition; examples of those variables in time are the soil pH or organic matter content; an example of a feature with strong dynamics is the soil temperature and moisture content. The aim of this study was to identify the variability of soil moisture on the field with and without plants using geostatistical methods. The soil moisture measurements were taken on the object with plant canopy and without plants (as reference). The measurements of soil moisture and meteorological components were taken within the period of April-July. The TDR moisture sensors covered 5 cm soil layers and were installed in the plots in the soil layers of 0-0.05, 0.05-0.1, 0.1-0.15, 0.2-0.25, 0.3-0.35, 0.4-0.45, 0.5-0.55, 0.8-0.85 m. Measurements of soil moisture were taken once a day, in the afternoon hours. For the determination of reciprocal correlation, precipitation data and data from soil moisture measurements with the TDR meter were used. Calculations of reciprocal correlation of precipitation and soil moisture at various depths were made for three objects - spring barley, rye, and bare soil, at the level of significance of p<0.05. No significant reciprocal correlation was found between the precipitation and soil moisture in the soil profile for any of the objects studied. Although the correlation analysis indicates a lack of correlation between the variables under consideration, observation of the soil

  10. Herbaceous vegetation productivity, persistence, and metals uptake on a biosolids-amended mine soil

    SciTech Connect

    Evanylo, G.K.; Abaye, A.O.; Dundas, C.; Zipper, C.E.; Lemus, R.; Sukkariyah, B.; Rockett, J.

    2005-10-01

    The selection of plant species is critical for the successful establishment and long-term maintenance of vegetation on reclaimed surface mined soils. A study was conducted to assess the capability of 16 forage grass and legume species in monocultures and mixes to establish and thrive on a reclaimed Appalachian surface mine amended with biosolids. The 0.15-ha coarse-textured, rocky, non-acid forming mined site was prepared for planting by grading to a 2% slope and amending sandstone overburden materials with a mixture of composted and dewatered, anaerobically digested biosolids at a rate of 368 Mg ha{sup -1} (dry weight). The high rate of biosolids applied provided favorable soil chemical properties but could not overcome physical property limitations due to shallow undeveloped soil perched atop a compacted soil layer at 25 cm depth. The plant species whose persistence and biomass production were the greatest after a decade or more of establishment (i.e., switchgrass, sericea lespedeza, reed canarygrass, tall fescue, and crownvetch) shared the physiological and reproductive characteristics of low fertility requirements, drought and moisture tolerance, and propagation by rhizome and/or stolons. Of these five species, two (tall fescue and sericea lespedeza) are or have been seeded commonly on Appalachian coal surface mines, and often dominate abandoned pasture sites. Despite the high rates of heavy metal-bearing biosolids applied to the soil, plant uptake of Cd, Cu, Ni, and Zn were well within critical concentrations more than a decade after establishment of the vegetation.

  11. 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.

  12. Dryland soil microbial communities display spatial biogeographic patterns associated with soil depth and soil parent material

    USGS Publications Warehouse

    Steven, Blaire; Gallegos-Graves, La Verne; Belnap, Jayne; Kuske, Cheryl R.

    2013-01-01

    Biological soil crusts (biocrusts) are common to drylands worldwide. We employed replicated, spatially nested sampling and 16S rRNA gene sequencing to describe the soil microbial communities in three soils derived from different parent material (sandstone, shale, and gypsum). For each soil type, two depths (biocrusts, 0–1 cm; below-crust soils, 2–5 cm) and two horizontal spatial scales (15 cm and 5 m) were sampled. In all three soils, Cyanobacteria and Proteobacteria demonstrated significantly higher relative abundance in the biocrusts, while Chloroflexi and Archaea were significantly enriched in the below-crust soils. Biomass and diversity of the communities in biocrusts or below-crust soils did not differ with soil type. However, biocrusts on gypsum soil harbored significantly larger populations of Actinobacteria and Proteobacteria and lower populations of Cyanobacteria. Numerically dominant operational taxonomic units (OTU; 97% sequence identity) in the biocrusts were conserved across the soil types, whereas two dominant OTUs in the below-crust sand and shale soils were not identified in the gypsum soil. The uniformity with which small-scale vertical community differences are maintained across larger horizontal spatial scales and soil types is a feature of dryland ecosystems that should be considered when designing management plans and determining the response of biocrusts to environmental disturbances.

  13. Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem carbon exchange.

    PubMed

    Domec, Jean-Christophe; King, John S; Noormets, Asko; Treasure, Emrys; Gavazzi, Michael J; Sun, Ge; McNulty, Steven G

    2010-07-01

    *Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially influencing both water use and carbon assimilation. *By measuring soil water content, sap flow and eddy covariance, we investigated the temporal variability of HR in a loblolly pine (Pinus taeda) plantation during months of normal and below-normal precipitation, and examined its effects on tree transpiration, ecosystem water use and carbon exchange. *The occurrence of HR was explained by courses of reverse flow through roots. As the drought progressed, HR maintained soil moisture above 0.15 cm(3) cm(-3) and increased transpiration by 30-50%. HR accounted for 15-25% of measured total site water depletion seasonally, peaking at 1.05 mm d(-1). The understory species depended on water redistributed by the deep-rooted overstory pine trees for their early summer water supply. Modeling carbon flux showed that in the absence of HR, gross ecosystem productivity and net ecosystem exchange could be reduced by 750 and 400 g C m(-2) yr(-1), respectively. *Hydraulic redistribution mitigated the effects of soil drying on understory and stand evapotranspiration and had important implications for net primary productivity by maintaining this whole ecosystem as a carbon sink.

  14. 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.

  15. Effect of the preparation method of support on the aqueous phase reforming of ethylene glycol over 2 wt% Pt/Ce0.15Zr0.85O2 catalysts.

    PubMed

    Kim, Jung-Hyun; Jeong, Kwang-Eun; Kim, Tae-Wan; Chae, Ho-Jeong; Jeong, Soon-Yong; Kim, Chul-Ung; Lee, Kwan-Young

    2013-08-01

    The effect of catalyst support on the aqueous phase reforming of ethylene glycol over supported 2 wt% Pt/Ce0.15Zr0.85O2 catalysts have been investigated. Various types of Ce0.15Zr0.85O2 mixed oxides were prepared by hydrothermal precipitation (CZH), modified precipitation (CZM), co-precipitation (CZC), sol-gel (CZS) methods, respectively. Catalysts were characterized by XRD, N2 sorption analysis, and cyclohexane dehydration for relative metal dispersion. The support effect on the activity of 2 wt% Pt/Ce0.15Zr0.85O2 catalysts with different preparation method was given as follows: CZH < CZM < CZC < CZS. Pt/Ce0.15Zr0.85O2 (CZS) catalyst showed good catalytic activity for APR reaction due to its high metal dispersion and reducibility. The effect of reaction conditions such as reaction temperature, weight hourly space velocity (WHSV) was also studied. The hydrogen production rate and hydrogen yield increased in proportion to the reaction temperature and corresponding system pressure, whereas WHSV did not affect.

  16. Evaluation of Effects of Sustained Decadal Precipitation Manipulations on Soil Carbon Stocks

    SciTech Connect

    Froeberg, Mats J; Hanson, Paul J; Todd Jr, Donald E; Johnson, Dale W.

    2008-01-01

    Throughout a 13 year period, the Throughfall Displacement Experiment sustained both increased (+33) and decreased (-33%) throughfall into an upland Oak forest in Tennessee. Organic (O) horizon carbon (C) stocks were measured at several occasions before, during and after the experiment and mineral soil C stocks before and after the experiment. In the O horizon, higher litter fall rates and slower decomposition lead to higher C stocks in the dry treatment compared to the ambient and wet. Dry plot accumulation of C in the O horizon was attributable to a combination of enhanced litter inputs and reduced decomposition. Implications of the immobilization of nutrient elements as long-term feedbacks are discussed. No treatment effect on C stocks was found in the mineral soil, but a significant long-term reduction in mineral soil C stocks was found between the start and the end at the experiment from 3.5 to 2.7% C in the 0-15 cm layer and from 0.6 to 0.5% in the 15-30 cm layer. Explanations for this significant trend in C storage were not readily apparent, but are fully discussed in the context of measurement bias, temperature, and primary production.

  17. Heavy metal concentrations in soils and vegetation in urban areas of Quezon City, Philippines.

    PubMed

    Navarrete, Ian A; Gabiana, Christella C; Dumo, Joan Ruby E; Salmo, Severino G; Guzman, Maria Aileen Leah G; Valera, Nestor S; Espiritu, Emilyn Q

    2017-04-01

    Limited data have been published on the chemistry of urban soils and vegetation in the Philippines. The aim of this study is to quantify the concentrations of heavy metals (i.e., Cr, Ni, Cu, Zn, and Pb) in soils and vegetation in the urban landscape of Quezon City, Philippines, and to elucidate the relationships between soil properties and the concentration of heavy metals pertaining to different land uses [i.e., protected forest (LM), park and wildlife area (PA), landfill (PL), urban poor residential and industrial areas (RA), and commercial areas (CA)]. Soil (0-15 cm) and senescent plant leaves were collected and were analyzed for soil properties and heavy metal concentrations. Results revealed that the concentrations of heavy metals (i.e., Cr, Ni, Cu, Zn, and Pb) in urban soils were higher in areas where anthropogenic activities or disturbance (PL, RA, and CA) were dominant as compared to the less disturbed areas (LM and PA). Organic matter and available phosphorous were strongly correlated with heavy metal concentrations, suggesting that heavy metal concentrations were primarily controlled by these soil properties. The average foliar heavy metal concentrations varied, ranging from 0 to 0.4 mg/kg for Cd, 0-10 mg/kg for Cr, 2-22 mg/kg for Cu, 0-5 mg/kg for Pb, and 11-250 mg/kg for Zn. The concentrations of Cd and Cr exceeded the critical threshold concentrations in some plants. Leaves of plants growing in PL (i.e., landfill) showed the highest levels of heavy metal contamination. Our results revealed that anthropogenic activities and disturbance caused by the rapid urbanization of the city are major contributors to the heavy metal accumulation and persistence in the soils in these areas.

  18. Phosphatase activity in relation to key litter and soil properties in mature subtropical forests in China.

    PubMed

    Hou, Enqing; Chen, Chengrong; Wen, Dazhi; Liu, Xian

    2015-05-15

    Phosphatase-mediated phosphorus (P) mineralization is one of the critical processes in biogeochemical cycling of P and determines soil P availability in forest ecosystems; however, the regulation of soil phosphatase activity remains elusive. This study investigated the potential extracellular activities of acid phosphomonoesterase (AcPME) and phosphodiesterase (PDE) and how they were related to key edaphic properties in the L horizon (undecomposed litter) and F/H horizon (fermented and humified litter) and the underlying mineral soil at the 0-15cm depth in eight mature subtropical forests in China. AcPME activity decreased significantly in the order of F/H horizon>L horizon>mineral soil horizon, while the order for PDE activity was L horizon=F/H horizon>mineral soil horizon. AcPME (X axis) and PDE (Y axis) activities were positively correlated in all horizons with significantly higher slope in the L and F/H horizons than in the mineral soil horizon. Both AcPME and PDE activities were positively related to microbial biomass C, moisture content and water-holding capacity in the L horizon, and were positively related to soil C:P, N:P and C:N ratios and fine root (diameter≤2mm) biomass in the mineral soil horizon. Both enzyme activities were also interactively affected by forest and horizon, partly due to the interactive effect of forest and horizon on microbial biomass. Our results suggest that modulator(s) of the potential extracellular activity of phosphatases vary with horizon, depending on the relative C, P and water availability of the horizon.

  19. VLA Images of Venus at 1.3 CM and 2 CM Wavelengths

    NASA Astrophysics Data System (ADS)

    Suleiman, S. H.; Kolodner, M. A.; Butler, B. J.; Steffes, P. G.

    1996-09-01

    On April 5, 1996, we performed an observation of Venus using the Very Large Array (VLA) at 15 GHz (2 cm) and 22 GHz (1.3 cm) simultaneously. High resolution continuum images for Venus were obtained at both frequencies. These images show significant polar darkening at latitudes above 60(deg) which is consistent with the results obtained by the Pioneer Venus Orbiter Infrared Radiometer (OIR) experiment (Taylor et al., J. Geophys. Res. 85, 7963-8006, 1980). These images are currently being used to detect potential spatial (longitudinal and latitudinal) variations in the abundances of gaseous sulfur dioxide (SO_2) and gaseous sulfuric acid (H_2SO_4) across the disk of Venus. Our new radiative transfer model (RTM) has shown that the emission spectrum is especially sensitive to the abundances of these constituents at these wavelengths. The detection of these constituents is being accomplished by matching the computed emission from our RTM to the measured emission of Venus by the VLA. Our RTM incorporates the newly developed Ben Reuven formalism which provides a more accurate characterization of the microwave absorption of gaseous SO_2 (Suleiman et al., J. Geophys. Res. 101, 4623-4635, 1996). A description of the observation, visibility data, and images are presented. This work was supported by the NASA Planetary Atmospheres Program under grant NAGW-533.

  20. Natural 'background' soil water repellency in conifer forests: its prediction and relationship to wildfire occurrence

    NASA Astrophysics Data System (ADS)

    Doerr, Stefan; Woods, Scott; Martin, Deborah; Casimiro, Marta

    2013-04-01

    therefore incorrect. It follows that, where pre-fire water repellency levels are not known or highly variable, post-fire soil water repellency conditions are an unreliable indicator in classifying soil burn severity. The terrain and soil variables examined showed, overall, no convincing relationship with the repellency levels observed (R2 < 0.15) except that repellency was limited in soils (i) developed over meta-sedimen- tary lithology and (ii) with clay contents >4%. This suggests that water repellency levels cannot be pre- dicted with confidence from common terrain or soil variables. This work is presented in the memory of the late Scott Woods, who was instrumental in the success of this study and an inspiration to us all.

  1. Soil-air relationships for toxaphene in the southern United States.

    PubMed

    Bidleman, Terry E; Leone, Andi

    2004-10-01

    Volatilization of toxaphene residues from agricultural soil was investigated at farms in the southern United States by collecting air samples 40 cm above the soil. The concentration of total toxaphene ranged over several orders of magnitude, from <3 to 6,500 ng g(-1) dry weight in soil, and <0.3 to 42 ng m(-3) in air. A log-log plot of total toxaphene concentrations in soil and overlying air showed a significant (p < 0.001) positive relationship, with r2 = 0.73. The soil/air fugacity ratio (FR) for 26 events ranged from 0.4 to 238, exceeded FR = 1.0 (soil/air equilibrium) in 24 events, and exceeded FR = 10 in 17 events. This indicates that toxaphene in air sampled at 40 cm generally was not at equilibrium but undersaturated with respect to the soil. Compared to a technical toxaphene standard, chromatographic profiles of toxaphene residues in soil and air showed alterations due to preferential degradation and volatilization of the components. Peaks matching the retention times of labile octachlorobornanes B8-531 and B8-806 + B8-809 were depleted in both soil and air relative to the more recalcitrant B8-1413 + B8-1945 and B8-2229. For each event, log-log plots were made of the dimensionless soil/air concentration quotient (Q) versus liquid-phase vapor pressure (PL, Pa) for 10 toxaphene components (peaks containing coeluting congeners) that spanned the volatility range of hepta- to nonachlorobornanes. Statistically significant linear relationships were obtained with r2 values for most events ranging from 0.54 to 0.96. Slopes for all but one event ranged from -1.01 to -1.53 and averaged -1.28 +/- 0.20. When regressions were carried out for only components one to nine, which cover the vapor pressure range of most components reported in ambient air, the average slope was reduced to -1.02 +/- 0.15. Previous models of toxaphene emission, transport, and deposition have considered only total toxaphene. These results provide a basis for modeling soil/air exchange on the basis

  2. Effects of dust-caused early snowmelt on soil moisture, soil carbon and nitrogen, and plant growth and reproductive output in a snow manipulation experiment

    NASA Astrophysics Data System (ADS)

    Conner, L. G.; Gill, R. A.

    2014-12-01

    Regional climate forecasts for the western United States predict slightly more snow accumulation during the winter but warmer springs and earlier spring snowmelt. Snowmelt will be further advanced by radiative forcing from dust and black carbon deposition on mountain snowpack. We expect earlier snowmelt to reduce regional water supplies (Painter et al., 2010) and suspect that it may also lead to drier soil conditions which could impact nutrient cycling and plant growth and reproduction in alpine and subalpine environments. Our snow manipulation experiment included 12 sites at two elevations in paired forest and meadow sites. We added dust to the snow surface during spring ablation. The dust treatment reduced snowpack by 20 to 40% and advanced the snowfree date by 9 to 14 days. Following snowmelt, there was a temporary difference in soil moisture in the upper 0-15 cm of soil between the treatment and control plots. Following snowmelt, the temporary differences in soil moisture quickly converged during soil drydown to a lower limit determined by the soil characteristics specific to each site. This brief window of differences in soil moisture may have temporary impacts on ecosystem processes; however, the impacts are mediated by plant and microbial phenology. Some of the plants and microbes in seasonally-snow-covered environments are adapted to take advantage of the early season environments which include low temperatures and frequent freezing, while other plants and microbes have evolved to avoid this transition period through prolonged dormancy. These adaptations, and the transient nature of environmental differences caused by early snowmelt, may limit the impacts of early snowmelt on carbon and nitrogen cycling and on plant growth and reproduction in subalpine forest and meadows.

  3. Characterizing Soil Organic Carbon Recalcitrance in Longleaf Pine (Pinus palustris Mill) Stands

    NASA Astrophysics Data System (ADS)

    Butnor, J. R.; Samuelson, L. J.; Anderson, P. H.; Gonzalez-Benecke, C. A.; Boot, C. M.; Cotrufo, M. F.; Heckman, K. A.; Jackson, J. A.; Johnsen, K. H.; Stokes, T.; Swanston, C.

    2015-12-01

    Historically, longleaf pine (LLP) stands in the southeastern US experienced frequent fires. Today managed LLP stands are burned at 2-5 year intervals to reduce fuels and hardwood competition and manage for biodiversity. These are not stand replacing fires, though considerable amounts of biomass are burned and the conversion rate to biochemically stabilized black carbon (BC) is unknown. The primary mechanisms for long-term carbon sequestration in soil are mineral association, biochemical transformation (e.g. pyrogenesis) and physical protection. We quantified the recalcitrance of soil organic carbon (SOC) and its oxidation resistant fraction (SOCR; defined as residual SOC following H2O2 treatment and dilute HNO3 digestion) using radiocarbon dating (SOC and SOCR) and benzene polycarboxylic acids (BPCA) as molecular markers for polyaromatic C associated with BC. Mineral stabilized C is largely represented by SOCR contents and BC by total BPCA contents. Soils were collected by depth (0-10, 10-20, 20-50, 50-100 cm) at 14 managed LLP stands in Louisiana (LA), Georgia (GA) and North Carolina (NC) burned every two to five years. Across all sites, SOC and SOCR contents declined with soil depth, though SOCR:SOC increased with depth (0.13, 0.15, 0.22, 0.31). SOCR was more 14C depleted than SOC and Δ14C values became more negative with soil depth (SOCR: -195, -318, -458, -553 vs. SOC 23, -39, -156, -334), indicating that SOCR had a much longer mean residence time. The Δ14C values correspond to mean ages of SOCR ranging from 1777 to 6969 years and of SOC from 84 to 3319 years. We obtained very low BPCA yield from SOCR, and it is unclear whether BC was absent or not accessible with the BPCA method. Preliminary analysis of total BPCA (bulk soil) indicates interactions between soil series and depth. Total BPCA concentration of SOC in the upper 10 cm was 136 g kg-1 C in LA and more than six times the concentration in GA and NC. On deep sands in NC, the highest BPCA concentration

  4. 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.

  5. Chrysanthemum CmNAR2 interacts with CmNRT2 in the control of nitrate uptake

    PubMed Central

    Gu, Chunsun; Zhang, Xiaoxue; Jiang, Jiafu; Guan, Zhiyong; Zhao, Shuang; Fang, Weimin; Liao, Yuan; Chen, Sumei; Chen, Fadi

    2014-01-01

    Nitrate transporters are an important component of plant growth and development. Chrysanthemum morifolium is an important ornamental species, for which a sufficient supply of nitrogenous fertilizer is required to maintain economic yields. In this study, the full-length cDNA of the nitrate transporter genes CmNRT2 and CmNAR2 were isolated. CmNRT2 transcript accumulation was inducible by both nitrate and ammonium, but the latter ion down-regulated the transcript accumulation of CmNAR2. CmNRT2 might be a plasma membrane localized protein, while CmNAR2 was distributed throughout the cell. CmNAR2 was shown to interact with CmNRT2 by in vitro and in vivo assays. Arabidopsis thaliana plants heterologously expressing CmNRT2 showed an increased rate of nitrate influx, while this trait was unaltered in plants expressing CmNAR2. Double transformants (CmNRT2 plus CmNAR2) exhibited an enhanced rate of nitrate influx into the root. Our data indicated that the interaction of CmNAR2 with CmNRT2 contributed to the uptake of nitrate. PMID:25060485

  6. 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).

  7. 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.

  8. Soil organic carbon accumulation during post-agricultural succession in a karst area, southwest China.

    PubMed

    Yang, Liqiong; Luo, Pan; Wen, Li; Li, Dejun

    2016-11-23

    This study was aimed to investigate the direction and magnitude of soil organic carbon (SOC) dynamics and the underlying mechanisms following agricultural abandonment in a subtropical karst area, southwest China. Two post-agriculture succession sequences including grassland (~10 years), shrubland (~29 years), secondary forest (~59 years) and primary forest with cropland as reference were selected. SOC and other soil physicochemical variables in the soil depth of 0-15cm (representing the average soil depth of the slope in the studied area) were measured. SOC content in the grassland was not significantly elevated relative to the cropland (42.0 ± 7.3 Mg C ha(-1)). SOC content in the shrubland reached the level of the primary forest. On average, SOC content for the forest was 92.6 ± 4.2 Mg C ha(-1), representing an increase of 120.4 ± 10.0% or 50.6 ± 4.2 Mg ha(-1) relative to the cropland. Following agricultural abandonment, SOC recovered to the primary forest level in about 40 years with a rate of 1.38 Mg C ha(-1) yr(-1). Exchangeable Ca and Mg were found to be the strongest predictors of SOC dynamics. Our results suggest that SOC content may recover rapidly following agricultural abandonment in the karst region of southwest China.

  9. The clustering of the SDSS main galaxy sample - II. Mock galaxy catalogues and a measurement of the growth of structure from redshift space distortions at z = 0.15

    NASA Astrophysics Data System (ADS)

    Howlett, Cullan; Ross, Ashley J.; Samushia, Lado; Percival, Will J.; Manera, Marc

    2015-05-01

    We measure redshift space distortions in the two-point correlation function of a sample of 63 163 spectroscopically identified galaxies with z < 0.2, an epoch where there are currently only limited measurements, from the Sloan Digital Sky Survey Data Release 7 main galaxy sample (MGS). Our sample, which we denote MGS, covers 6813 deg2 with an effective redshift zeff = 0.15 and is described in our companion paper (Paper I), which concentrates on baryon acoustic oscillation (BAO) measurements. In order to validate the fitting methods used in both papers, and derive errors, we create and analyse 1000 mock catalogues using a new algorithm called PICOLA to generate accurate dark matter fields. Haloes are then selected using a friends-of-friends algorithm, and populated with galaxies using a halo-occupation distribution fitted to the data. Using errors derived from these mocks, we fit a model to the monopole and quadrupole moments of the MGS correlation function. If we assume no Alcock-Paczynski (AP) effect (valid at z = 0.15 for any smooth model of the expansion history), we measure the amplitude of the velocity field, fσ8, at z = 0.15 to be 0.49_{-0.14}^{+0.15}. We also measure fσ8 including the AP effect. This latter measurement can be freely combined with recent cosmic microwave background results to constrain the growth index of fluctuations, γ. Assuming a background Λ cold dark matter cosmology and combining with current BAO data, we find γ = 0.64 ± 0.09, which is consistent with the prediction of general relativity (γ ≈ 0.55), though with a slight preference for higher γ and hence models with weaker gravitational interactions.

  10. Lead removal via soil washing and leaching

    NASA Astrophysics Data System (ADS)

    Lin, H. K.; Man, X. D.; Walsh, D. E.

    2001-12-01

    A soil washing and leaching process was tested for removing lead from soils. A soil-washing circuit, including size and gravity separations, was employed to remove the coarse metallic lead particles, while the leaching was applied to remove fine metallic lead particles and other lead species. The soil-washing tests proved that the metallic lead particles larger than 0.15 mm (100 mesh) could be effectively removed. The sodium-chloride-based leaching solution with ferric chloride or sodium hypochlorite as oxidants was adopted in the leaching. The leaching experimental results indicated that under the pH of 2 and Eh of 1,300 mV, the metallic lead particles smaller than 0.15 mm and other lead species can be dissolved in the leaching solution within 60 minutes.

  11. Managing compost stability and amendment to soil to enhance soil heating during soil solarization.

    PubMed

    Simmons, Christopher W; Guo, Hongyun; Claypool, Joshua T; Marshall, Megan N; Perano, Kristen M; Stapleton, James J; Vandergheynst, Jean S

    2013-05-01

    Soil solarization is a method of soil heating used to eradicate plant pathogens and weeds that involves passive solar heating of moist soil mulched (covered) with clear plastic tarp. Various types of organic matter may be incorporated into soil prior to solarization to increase biocidal activity of the treatment process. Microbial activity associated with the decomposition of soil organic matter may increase temperatures during solarization, potentially enhancing solarization efficacy. However, the level of organic matter decomposition (stability) necessary for increasing soil temperature is not well characterized, nor is it known if various amendments render the soil phytotoxic to crops following solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays. Amendment of soil with 10%(g/g) compost containing 16.9 mg CO2/gdry weight organic carbon resulted in soil temperatures that were 2-4 °C higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization.

  12. Fine-sized LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders prepared by combined process of gas-phase reaction and solid-state reaction methods

    NASA Astrophysics Data System (ADS)

    Ju, Seo Hee; Kang, Yun Chan

    The Ni-rich precursor powders with spherical shape and filled morphologies were prepared by spray pyrolysis from the spray solution with citric acid, ethylene glycol and a drying control chemical additive. The precursor powders with controlled morphologies formed the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders with spherical shape and fine size by solid-state reaction with lithium hydroxide. However, the cathode powders prepared from the spray solution without additives had irregular morphologies and were large in size. The precursor powders with hollow and porous morphologies formed cathode powders with irregular and aggregated morphologies. The composition ratios of the nickel, cobalt and manganese components were maintained in the as-prepared, precursor and cathode powders. The initial discharge capacity of the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders with spherical shape and fine size tested at a temperature of 55 °C under a constant current density of 0.5 C was 215 mAh g -1. The discharge capacity of the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders decreased to 81% of the initial value after 30 cycles.

  13. Synthesis cathode material LiNi0.80Co0.15Al0.05O2 with two step solid-state method under air stream

    NASA Astrophysics Data System (ADS)

    Xia, Shubiao; Zhang, Yingjie; Dong, Peng; Zhang, Yannan

    2014-01-01

    A facile generic strategy of solid-state reaction under air atmosphere is employed to prepare LiNi0.8Co0.15Al0.05O2 layer structure micro-sphere as cathodes for Li-ion batteries. The impurity phase has been eliminated wholly without changing the R-3m space group of LiNi0.8Co0.15Al0.05O2. The electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathodes depend on the sintering step, temperature, particle size and uniformity. The sample pre-sintered at 540 °C for 12 h and then sintered at 720 °C for 28 h exhibits the best electrochemical performance, which delivers a reversible capacity of 180.4, 165.8, 154.7 and 135.6 mAhg-1 at 0.2 C, 1 C, 2 C and 5 C, respectively. The capacity retention keeps over 87% after 76 cycles at 1 C. This method is simple, cheap and mass-productive, and thus suitable to large scale production of NCA cathodes directly used for lithium ion batteries.

  14. Anisotropy and Vortex Pinning of Heavy Ion irradiated SmFeAsO0.8F0.15 and BaFe2(As1-xPx)2 Crystals

    NASA Astrophysics Data System (ADS)

    Kwok, Wai-Kwong; Fang, Lei; Chaparro, Carlos; Jia, Ying; Welp, Ulrich; Koshelev, Alexei; Xu, Shaofei; Crabtree, George; Karpinski, Janusz

    2012-02-01

    We report specific heat and magnetization measurements on SmFeAsO0.8F0.15 and BaFe2(As1-xPx)2 single crystals irradiated with high energy heavy ions of 1.4GeV Pb to dose matching fields up to 4 Tesla. We find a nearly one half reduction in the superconducting anisotropy and doubling of the irreversibility field in SmFeAsO0.8F0.15 after irradiation and virtually no change in the zero-field superconducting transition temperature. In both SmFeAsO0.8F0.15 and BaFe2(As1-xPx)2 crystals, we find a substantial increase in the critical current determined from SQUID and micro-Hall probe magnetization measurements. Pinning force analysis on proton and heavy ion irradiated pristine overdoped BaFe2(As1-xPx)2 crystals indicates presence of induced δTc-type pinning defects in these samples.

  15. 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.

  16. Decoupled scenario between the conductive carriers and the ferromagnetism in epitaxial Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O thin films

    SciTech Connect

    Zhu, Dapeng; Liu, Guolei; Tian, Yufeng E-mail: shishenyan@sdu.edu.cn; Yan, Shishen E-mail: shishenyan@sdu.edu.cn; Cai, Li; Fu, Maoxiang; Zhang, Jie; Zhang, Kun; Ye, Shengtao; Li, Huanhuan; Hu, Shujun; Chen, Yanxue; Kang, Shishou; Dai, Youyong; Mei, Liangmo; Cao, Qiang

    2014-08-18

    A series of Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O (0 ≤ x ≤ 0.3) thin films were fabricated by plasma-assisted molecular-beam epitaxy to investigate the correlation between the electrical transport properties and the ferromagnetism. It is observed that the saturation magnetization remains almost unchanged even though the resistivity of the Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O films dramatically increases more than 6 orders with increasing Mg concentration. Moreover, the absence of detectable anomalous Hall effects and very small magnetoresistance in the films reveal the absence of spin polarization of conductive carriers and very weak spin-dependent scattering or tunneling processes. All these results suggest that the conductive carriers are decoupled with the ferromagnetism in the Zn{sub 0.85−x}Mg{sub x}Co{sub 0.15}O films.

  17. Electronic structural studies on the improved thermal stability of Li(Ni0.8Co0.15Al0.05)O2 by ZrO2 coating for lithium ion batteries

    DOE PAGES

    Kim, Ji-Young; Kim, Sang Hoon; Kim, Dong Hyun; ...

    2017-03-21

    The electronic structures of bare and ZrO2-coated Li(Ni0.8Co0.15Al0.05)O2 electrode systems were investigated using a combination of time-resolved X-ray diffraction and soft X-ray absorption spectroscopy (XAS) techniques. The ZrO2 coating on the surface of Li(Ni0.8Co0.15Al0.05)O2 was effective in elevating the onset temperature of the dissociation of charged Li0.33(Ni0.8Co0.15Al0.05)O2, which will enhance the safety of Li-ion cells. Lastly, soft XAS spectra of the Ni LII,III-edge in the partial electron yield mode were obtained, which showed that the enhanced electrochemical properties and thermal stability of the cathode materials by ZrO2 coating can be attributed to the suppression of unwanted Ni oxidation state changesmore » at the surface.« less

  18. Monitoring of Lead (Pb) Pollution in Soils and Plants Irrigated with Untreated Sewage Water in Some Industrialized Cities of Punjab, India.

    PubMed

    Sikka, R; Nayyar, V K

    2016-04-01

    Soil and plant samples were collected from sewage and tubewell irrigated sites from three industrially different cities of Punjab (India) viz. Ludhiana, Jalandhar and Malerkotla. The extent of lead (Pb) pollution was assessed with respect to background concentration of tubewell irrigation. In sewage irrigated surface soil layer (0-15 cm), the extent of Pb accumulation was 4.61, 4.20 and 2.26 times higher than those receiving tubewell irrigation sites in Ludhiana, Jalandhar and Malerkotla, respectively. Multiple regression analysis showed that soil pH, organic carbon, calcium carbonate and clay were significant soil parameters explaining the variation in available soil Pb. The mean Pb content in plants receiving sewage irrigation was 4.56, 5.48 and 2.72 times higher than tubewell irrigation in Ludhiana, Jalandhar and Malerkotla, respectively. The content of Pb in plants receiving sewage irrigation revealed that, assuming a weekly consumption of 500-1000 g of vegetables grown on sewage irrigated soils by an adult of 70 kg body weight, the Pb intake may far exceed the World Health Organization proposed tolerable weekly intake of Pb.

  19. [Distribution of Urban Soil Heavy Metal and Pollution Evaluation in Different Functional Zones of Yinchuan City].

    PubMed

    Wang, You-qi; Bai, Yi-ru; Wang, Jian-yu

    2016-02-15

    Surface soil samples (0-20 cm) from eight different functional areas in Yinchuan city were collected. There were 10 samples respectively in each functional area. The urban soil heavy metals (Zn, Cd, Pb, Mn, Cu and Cr) pollution characteristics and sources in eight different functional areas were evaluated by mathematical statistics and geostatistical analysis method. Meanwhile, the spatial distributions of heavy metals based on the geography information system (GIS) were plotted. The average values of total Zn, Cd, Pb, Mn, Cu and Cr were 74.87, 0.15, 29.02, 553.55, 40.37 and 80.79 mg x kg(-1), respectively. The results showed that the average value of soil heavy metals was higher than the soil background value of Ningxia, which indicated accumulation of the heavy metals in urban soil. The single factor pollution index of soil heavy metals was in the sequence of Cu > Pb > Zn > Cr > Cd > Mn. The average values of total Zn, Cd, Pb and Cr were higher in north east, south west and central city, while the average values of Mn and Cu were higher in north east and central city. There was moderate pollution in road and industrial area of Yinchuan, while the other functional areas showed slight pollution according to Nemoro synthesis index. The pollution degree of different functional areas was as follows: road > industrial area > business district > medical treatment area > residential area > public park > development zone > science and education area. The results indicated that the soil heavy metal pollution condition in Yinchuan City has been affected by human activities with the development of economy.

  20. Effects of tropical ecosystem engineers on soil quality and crop performance under different tillage and residue management

    NASA Astrophysics Data System (ADS)

    Pulleman, Mirjam; Paul, Birthe; Fredrick, Ayuke; Hoogmoed, Marianne; Hurisso, Tunsisa; Ndabamenye, Telesphore; Saidou, Koala; Terano, Yusuke; Six, Johan; Vanlauwe, Bernard

    2014-05-01

    Feeding a future global population of 9 billion will require a 70-100% increase in food production, resulting in unprecedented challenges for agriculture and natural resources, especially in Sub-saharan Africa (SSA). Agricultural practices that contribute to sustainable intensification build on beneficial biological interactions and ecosystem services. Termites are the dominant soil ecosystem engineers in arid to sub-humid tropical agro-ecosystems. Various studies have demonstrated the potential benefits of termites for rehabilitation of degraded and crusted soils and plant growth in semi-arid and arid natural ecosystems. However, the contribution of termites to agricultural productivity has hardly been experimentally investigated, and their role in Conservation Agriculture (CA) systems remains especially unclear. Therefore, this study aimed to quantify the effects of termites and ants on soil physical quality and crop productivity under different tillage and residue management systems in the medium term. A randomized block trial was set up in sub-humid Western Kenya in 2003. Treatments included a factorial combination of residue retention and removal (+R/-R) and conventional and reduced tillage (+T/-T) under a maize (Zea mays L.) and soybean (Glyxine max. L.) rotation. A macrofauna exclusion experiment was superimposed in 2005 as a split-plot factor (exclusion +ins; inclusion -ins) by regular applications of pesticides (Dursban and Endosulfan) in half of the plots. Macrofauna abundance and diversity, soil aggregate fractions, soil carbon contents and crop yields were measured between 2005 and 2012 at 0-15 cm and 15-30 cm soil depths. Termites were the most important macrofauna species, constituting between 48-63% of all soil biota, while ants were 13-34%, whereas earthworms were present in very low numbers. Insecticide application was effective in reducing termites (85-56% exclusion efficacy) and earthworms (87%), and less so ants (49-81%) at 0-15 cm soil depth

  1. Carbon, Nitrogen and Fungal mycelium in the organic and in the mineral soil layers across a chronosequence of Stone pine Forest on Mount Vesuvius

    NASA Astrophysics Data System (ADS)

    de Marco, Anna; Giordano, Maria; Esposito, Fabrizio; Virzo de Santo, Amalia

    2010-05-01

    Forest ecosystems act as a substantial carbon sink and store about 20% of all soil C. The amount of organic matter sequestered in the soil is dependent on the quantity of plant litter delivered to the soil as well as to the extent of litter decomposition. Stone pine forests are common in the Mediterranean areas of southern Italy, were this tree has been largely used for afforestation of volcanic substrates on Mount Vesuvius. Nevertheless, very little is known about carbon accumulation in Stone pine soil as well as about soil organic matter turnover in the organic and in the mineral soil layers. The aim of this study was to assess, along the whole soil profile, the concentration of C and N and the amount of fungal mycelium across a chronosequence encompassing a 36y, a 66y and a 96y old Stone pine forest within the National Park of Vesuvius. The chronosequence allows to estimate the changes with forest age in C and N concentration and the allocation of organic matter below-ground. The amount of fungal mycelium, particularly the active mycelium, at different depth along the soil profile is an indicator of the organic matter turn-over. The forest stands had been implanted on the same type of parent material, i.e. on lava. The sandy mineral soil was 15 cm deep in the youngest forest and reached a maximum depth of 37 cm in the two older forests. Litter fall (2006-2009) steadily increased from the youngest to the oldest forest stand (3828, 6144 and 7831 Kg/ha/y, respectively) and was positively related to tree basal area. C and N concentration in the organic soil layers (litter and humus) of the three stands did not change remarkably with forest age. In contrast, in the 0-15 cm mineral layer, C and N concentrations were about threefold higher in the 66y old compared to the 36y old forest stand. A further increase (by 2,4 for C and by 1,5 for N) was observed in the 96y old compared to the 66y old forest stand. In the deeper (15-37 cm) mineral soil of the two older forest

  2. Is soil carbon storage underestimated?

    PubMed

    Díaz-Hernández, José Luis

    2010-06-01

    An accurate evaluation of the carbon stored in soils is essential to fully understand the role of soils as source or sink of atmospheric CO(2), as well as the feedback processes involved in soil-atmosphere CO(2) exchange. Depth and strategies of sampling have been, and still are, sources of uncertainties, because most current estimates of carbon storage in soils are based on conventional soil surveys and data sets compiled primarily for agricultural purposes. In a study of the Guadix-Baza basin, a semiarid area of southern Spain, sizeable amounts of carbon have been found stored in the subsoil. Total carbon estimated within 2-m was 141.3 kg Cm(-2) compared to 36.1 kg Cm(-2) if estimates were based solely on conventional soil depths (e.g. 40-cm in Regosols and 100-cm in Fluvisols). Thus, the insufficient sampling depth could lead to considerable underestimation of global soil carbon. In order to correctly evaluate the carbon content in world soils, more specific studies must be planned and carried out, especially in those soils where caliche and other carbonated cemented horizons are present.

  3. Soil property effects on wind erosion of organic soils

    NASA Astrophysics Data System (ADS)

    Zobeck, Ted M.; Baddock, Matthew; Scott Van Pelt, R.; Tatarko, John; Acosta-Martinez, Veronica

    2013-09-01

    Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (OM > 20%) in half or more of the upper 80 cm. Forty two states have a total of 21 million ha of Histosols in the United States. These soils, when intensively cropped, are subject to wind erosion resulting in loss of crop productivity and degradation of soil, air, and water quality. Estimating wind erosion on Histosols has been determined by USDA-Natural Resources Conservation Service (NRCS) as a critical need for the Wind Erosion Prediction System (WEPS) model. WEPS has been developed to simulate wind erosion on agricultural land in the US, including soils with organic soil material surfaces. However, additional field measurements are needed to understand how soil properties vary among organic soils and to calibrate and validate estimates of wind erosion of organic soils using WEPS. Soil properties and sediment flux were measured in six soils with high organic contents located in Michigan and Florida, USA. Soil properties observed included organic matter content, particle density, dry mechanical stability, dry clod stability, wind erodible material, and geometric mean diameter of the surface aggregate distribution. A field portable wind tunnel was used to generate suspended sediment and dust from agricultural surfaces for soils ranging from 17% to 67% organic matter. The soils were tilled and rolled to provide a consolidated, friable surface. Dust emissions and saltation were measured using an isokinetic vertical slot sampler aspirated by a regulated suction source. Suspended dust was sampled using a Grimm optical particle size analyzer. Particle density of the saltation-sized material (>106 μm) was inversely related to OM content and varied from 2.41 g cm-3 for the soil with the lowest OM content to 1.61 g cm-3 for the soil with highest OM content. Wind erodible material and the geometric mean diameter of the surface soil were inversely related to dry clod

  4. Effect of DTPA on concentration ratios of /sup 237/Np and /sup 244/Cm in vegetative parts of bush bean and barley

    SciTech Connect

    Romney, E.M.; Wallace, A.; Mueller, R.T.; Cha, J.W.; Wood, R.A.

    1981-07-01

    We grew bush beans, barley, and rice in two different soils in a glasshouse with /sup 237/Np or /sup 244/Cm mixed into separate containers of the soil. The chelating agent DTPA at 100 ..mu..g/g soil was added to half of the containers. The concentration ratio (CR) for /sup 237/Np without DTPA was two orders of magnitude higher than for /sup 244/Cm without DTPA for all three plant species. The DTPA increased the CR of /sup 244/Cm by two to three orders of magnitude, but had no influence on that for /sup 237/Np. In bush beans, both /sup 237/Np and /sup 244/Cm CRs were higher in primary leaves than in trifoliate leaves, which were higher than for stems. The CRs for bush beans were generally higher for both /sup 237/Np and /sup 244/Cm than for either barley or rice, especially without DTPA.

  5. The amino acid composition of the Sutter's Mill CM2 carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Burton, Aaron S.; Glavin, Daniel P.; Elsila, Jamie E.; Dworkin, Jason P.; Jenniskens, Peter; Yin, Qing-Zhu

    2014-11-01

    We determined the abundances and enantiomeric compositions of amino acids in Sutter's Mill fragment #2 (designated SM2) recovered prior to heavy rains that fell April 25-26, 2012, and two other meteorite fragments, SM12 and SM51, that were recovered postrain. We also determined the abundance, enantiomeric, and isotopic compositions of amino acids in soil from the recovery site of fragment SM51. The three meteorite stones experienced terrestrial amino acid contamination, as evidenced by the low D/L ratios of several proteinogenic amino acids. The D/L ratios were higher in SM2 than in SM12 and SM51, consistent with rain introducing additional L-amino acid contaminants to SM12 and SM51. Higher percentages of glycine, β-alanine, and γ-amino-n-butyric acid were observed in free form in SM2 and SM51 compared with the soil, suggesting that these free amino acids may be indigenous. Trace levels of D+L-β-aminoisobutyric acid (β-AIB) observed in all three meteorites are not easily explained as terrestrial contamination, as β-AIB is rare on Earth and was not detected in the soil. Bulk carbon and nitrogen and isotopic ratios of the SM samples and the soil also indicate terrestrial contamination, as does compound-specific isotopic analysis of the amino acids in the soil. The amino acid abundances in SM2, the most pristine SM meteorite analyzed here, are approximately 20-fold lower than in the Murchison CM2 carbonaceous chondrite. This may be due to thermal metamorphism in the Sutter's Mill parent body at temperatures greater than observed for other aqueously altered CM2 meteorites.

  6. Effects of electron irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nicoletta, C. A.

    1973-01-01

    One OHM-cm and 10 OHM-cm silicon solar cells were exposed to 1.0 MeV electrons at a fixed flux of 10 to the 11th power e/sq cm/sec and fluences of 10 to the 13th power, 10 to the 14th power and 10 to the 15th power e/sq.cm. 1-V curves of the cells were made at room temperature, - 63 C and + or - 143 C after each irradiation. A value of 139.5 mw/sq cm was used as AMO incident energy rate per unit area. The 10 OHM-cm cells appear more efficient than 1 OHM-cm cells after exposure to a fluence greater than 10 to the 14th power e/sq cm. The 1.0 MeV electron damage coefficients for both 1 OHM-cm and 10 OHM-cm cells are somewhat less than those for previously irradiated cells at room temperature. The values of the damage coefficients increase as the cell temperatures decrease. Efficiencies pertaining to maximum power output are about the same as those of n on p silicon cells evaluated previously.

  7. Charge transfer to the local singlet states as a function of Li content in La 2Cu 1- xLi xO 4 and La 1.85Sr 0.15Cu 1- xLi xO 4

    NASA Astrophysics Data System (ADS)

    Rykov, Alexandre I.; Yasuoka, Hiroshi; Ueda, Yutaka

    1995-02-01

    Magnetic susceptibility (χ) and NMR/NQR measurements were performed on La 2Cu 1- xLi xO 4 0≤ x≤0.5) and La 1.85Sr 0.15Cu 1- xLi xO 4 (0≤ x≤0.425). The narrow 63Cu NQR line at νQ = 46.3 MHz (1.3 K) is detected in La 2Cu 0.5Li 0.5O 4. This frequency is higher than all 63Cu-NQR frequencies found so far in all the cuprates. Moreover, a further increase of νQ is observed in the solid solutions La 2Cu 1- xLi xO 4 with decreasing x. Corresponding electric field gradients (EFG's) are considered in terms of ionic and cluster models. The 3d hole density nx2- y2 ≈ 1 and the radial average < r-3> ≈ 9.5 a.u. are derived from the EFG's, suggesting the d 9L state of the formally trivalent copper. The antiferromagnetic ordering is rapidly suppressed as a function of x in the La 2Cu 1- xLi xO 4, and for x ≥ 0.03 we find TN ≈ 0. The evolution of χ vs. x shows a gradual decrease of Cu spin susceptibility and its disappearance in the diamagnetic La 2Cu 0.5Li 0.5O 4, in which χ = -6.7 × 10 -5 cm 3/mole is composed of Van Vleck and core terms. The electronic state is implied to be a local singlet ( 1A 1g) of primarily d 9L character. The quadrupole signature of the local singlet in the range 46.3 ≤ 63ν Q ≤ 47.0 MHz is observed for x > 0.15 in both systems, La 2Cu 1- xLi xO 4 and La 1.85Sr 0.15Cu 1- xLi xO 4. The differentiation of charge between local singlet and conductivity band states is discussed.

  8. Structural and large magnetocaloric properties of La0.67-xYxBa0.23Ca0.1MnO3 perovskites (0≤x≤0.15)

    NASA Astrophysics Data System (ADS)

    Abassi, Mounira; Dhahri, N.; Dhahri, J.; HLIL, E. K.

    2014-09-01

    La0.67Ba0.23Ca0.1MnO3 doped with different amounts of yttrium (Y) result in the series La0.67-xYxBa0.23Ca0.1MnO3 (LYBCMO) (x=0.00, 0.05, 0.10 and 0.15) which was synthesized by conventional solid state ceramics route. All samples show a rhombohedral structure (space group R3 barc) at room temperature. A transition from a paramagnetic to a ferromagnetic phase is observed at Curie temperature, TC. It has been found that the substitution of Y on the La site causes a reduction in TC. Analyses of crystallographic data suggested a strong correlation between structural properties and magnetism. As an example, a relationship between the distortion of MnO6 octahedron and the reduction in Curie temperature. The magnetic entropy change (-ΔS)m was estimated from isothermal magnetization curves. It decreases from 4.91 J/kg K at 350 k (x=0.00) to 4.14 J/kg K at 289 K (x=0.15) with the increase of Y content under μ0H=5 T. The relative cooling power (RCP) is found to be 365 J/kg for La0.67Ba0.23Ca0.1MnO3 and 288 J/kg for La0.52Y0.15Ba0.23Ca0.1MnO3 in the magnetic field change of 5 T. From these results, La0.67-xYxBa0.23Ca0.1MnO3 materials are strongly suggested for use as active refrigerants in magnetic refrigeration technology at near room temperature.

  9. Phase equilibria in the Mo-Fe-P system at 800 °C and structure of ternary phosphide (Mo(1-x)Fe(x))3P (0.10 ≤ x ≤ 0.15).

    PubMed

    Oliynyk, Anton O; Lomnytska, Yaroslava F; Dzevenko, Mariya V; Stoyko, Stanislav S; Mar, Arthur

    2013-01-18

    Construction of the isothermal section in the metal-rich portion (<67 atom % P) of the Mo-Fe-P phase diagram at 800 °C has led to the identification of two new ternary phases: (Mo(1-x)Fe(x))(2)P (x = 0.30-0.82) and (Mo(1-x)Fe(x))(3)P (x = 0.10-0.15). The occurrence of a Co(2)Si-type ternary phase (Mo(1-x)Fe(x))(2)P, which straddles the equiatomic composition MoFeP, is common to other ternary transition-metal phosphide systems. However, the ternary phase (Mo(1-x)Fe(x))(3)P is unusual because it is distinct from the binary phase Mo(3)P, notwithstanding their similar compositions and structures. The relationship has been clarified through single-crystal X-ray diffraction studies on Mo(3)P (α-V(3)S-type, space group I42m, a = 9.7925(11) Å, c = 4.8246(6) Å) and (Mo(0.85)Fe(0.15))(3)P (Ni(3)P-type, space group I4, a = 9.6982(8) Å, c = 4.7590(4) Å) at -100 °C. Representation in terms of nets containing fused triangles provides a pathway to transform these closely related structures through twisting. Band structure calculations support the adoption of these structure types and the site preference of Fe atoms. Electrical resistivity measurements on (Mo(0.85)Fe(0.15))(3)P reveal metallic behavior but no superconducting transition.

  10. Ferroic phase transition of tetragonal Pb0.6-xCaxBi0.4(Ti0.75Zn0.15Fe0.1)O3 ceramics: Factors determining Curie temperature

    NASA Astrophysics Data System (ADS)

    Yu, Jian; An, Fei-fei; Cao, Fei

    2014-05-01

    In this paper, ferroelectric phase transitions of Pb0.6-xCaxBi0.4(Ti0.75Zn0.15Fe0.1)O3 with x ≤ 0.20 ceramics were experimentally measured and a change from first-order to relaxor was found at a critical composition x ˜ 0.19. With increasing Ca content of x ≤ 0.18, Curie temperature and tetragonality was found decrease but piezoelectric constant and dielectric constant increase in a quadratic polynomial relationship as a function of x, while the ferroic Curie temperature and ferroelastic ordering parameter of tetragonality are correlated in a quadratic polynomial relationship. Near the critical composition of ferroic phase transition from first-order to relaxor, the Pb0.42Ca0.18Bi0.4(Ti0.75Zn0.15Fe0.1)O3 and 1 mol % Nb + 0.5 mol % Mg co-doped Pb0.44Ca0.16Bi0.4(Ti0.75Zn0.15Fe0.1)O3 ceramics exhibit a better anisotropic piezoelectric properties than those commercial piezoceramics of modified-PbTiO3 and PbNb2O6. At last, those factors including reduced mass of unit cell, mismatch between cation size and anion cage size, which affect ferroic Curie temperature and ferroelastic ordering parameter (tetragonality) of tetragonal ABO3 perovskites, are analyzed on the basis of first principle effective Hamiltonian and the reduced mass of unit cell is argued a more universal variable than concentration to determine Curie temperature in a quadratic polynomial relationship over various perovskite-structured solid solutions.

  11. 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.

  12. 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.

  13. Impact of long-term forest enrichment planting on the biological status of soil in a deforested dipterocarp forest in Perak, Malaysia.

    PubMed

    Karam, D S; Arifin, A; Radziah, O; Shamshuddin, J; Majid, N M; Hazandy, A H; Zahari, I; Nor Halizah, A H; Rui, T X

    2012-01-01

    Deforestation leads to the deterioration of soil fertility which occurs rapidly under tropical climates. Forest rehabilitation is one of the approaches to restore soil fertility and increase the productivity of degraded areas. The objective of this study was to evaluate and compare soil biological properties under enrichment planting and secondary forests at Tapah Hill Forest Reserve, Perak after 42 years of planting. Both areas were excessively logged in the 1950s and left idle without any appropriate forest management until 1968 when rehabilitation program was initiated. Six subplots (20 m × 20 m) were established within each enrichment planting (F1) and secondary forest (F2) plots, after which soil was sampled at depths of 0-15cm (topsoil) and 15-30 cm (subsoil). Results showed that total mean microbial enzymatic activity, as well as biomass C and N content, was significantly higher in F1 compared to F2. The results, despite sample variability, suggest that the rehabilitation program improves the soil biological activities where high rate of soil organic matter, organic C, N, suitable soil acidity range, and abundance of forest litter is believed to be the predisposing factor promoting higher population of microbial in F1 as compared to F2. In conclusion total microbial enzymatic activity, biomass C and biomass N evaluation were higher in enrichment planting plot compared to secondary forest. After 42 years of planting, rehabilitation or enrichment planting helps to restore the productivity of planted forest in terms of biological parameters.

  14. 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.

  15. 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.

  16. Effects of proton irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nicoletta, C. A.

    1973-01-01

    The 1 ohm-cm and 10 ohm-cm silicon solar cells were exposed to 1.0 MeV protons at a fixed flux of 10 to the 9th power P/sq cm-sec and fluences of 10 to the 10th power, 10 to the 11th power, 10 to the 12th power and 3 X 10 to the 12th power P/sq cm. I-V curves of the cells were made at room temperature, 65 C and 165 C after each irradiation. A value of 139.5 mw/sq cm was taken as AMO incident energy rate per unit area. Degradation occurred for both uncovered 1 ohm-cm and 10 ohm-cm cells. Efficiencies are generally higher than those of comparable U.S. cells tested earlier. Damage (loss in maximum power efficiency) with proton fluence is somewhat higher for 10 ohm-cm cells, measured at the three temperatures, for fluences above 2 X 10 to the 11th power P/sq cm. Cell efficiency, as expected, changes drastically with temperature.

  17. Fast neutron induced fission cross sections of {sup 242m}Am, {sup 245}Cm, {sup 247}Cm

    SciTech Connect

    Fursov, B.I.; Samylin, B.F.; Smirenkin, G.N.; Polynov, V.N.

    1994-12-31

    The experimental data on {sup 242m}Am, {sup 245}Cm and {sup 247}Cm fission cross sections in the 0.13-7.2 Mev neutron energy range are presented. The measurements were made at Van-de-Graaf accelerators with monoenergetic neutron sources. The total data errors are 3.8% for {sup 242m}Am, 3.5% for {sup 245}Cm and 4.5% for {sup 247}Cm. The results given in this paper are preliminary ones.

  18. Pyrogenic carbon in Australian soils.

    PubMed

    Qi, Fangjie; Naidu, Ravi; Bolan, Nanthi S; Dong, Zhaomin; Yan, Yubo; Lamb, Dane; Bucheli, Thomas D; Choppala, Girish; Duan, Luchun; Semple, Kirk T

    2017-02-16

    Pyrogenic carbon (PyC), the combustion residues of fossil fuel and biomass, is a versatile soil fraction active in biogeochemical processes. In this study, the chemo-thermal oxidation method (CTO-375) was applied to investigate the content and distribution of PyC in 30 Australian agricultural, pastoral, bushland and parkland soil with various soil types. Soils were sampled incrementally to 50cm in 6 locations and at another 7 locations at 0-10cm. Results showed that PyC in Australian soils typically ranged from 0.27-5.62mg/g, with three Dermosol soils ranging within 2.58-5.62mg/g. Soil PyC contributed 2.0-11% (N=29) to the total organic carbon (TOC), with one Ferrosol as high as 26%. PyC was concentrated either in the top (0-10cm) or bottom (30-50cm) soil layers, with the highest PyC:TOC ratio in the bottom (30-50cm) soil horizon in all soils. Principal component analysis - multiple linear regression (PCA-MLR) suggested the silt-associated organic C factor accounted for 38.5% of the variation in PyC. Our findings suggest that PyC is an important fraction of the TOC (2.0-11%, N=18) and chemically recalcitrant organic C (ROC) obtained by chemical C fractionation method accounts for a significant proportion of soil TOC (47.3-84.9%, N=18). This is the first study comparing these two methods, and it indicates both CTO-375 and C speciation methods can determine a fraction of recalcitrant organic C. However, estimated chemically recalcitrant organic carbon pool (ROC) was approximately an order of magnitude greater than that of thermally stable organic carbon (PyC).

  19. Erosion rates, stochasticity, and abiotic vs. biotic bedrock to soil production mechanisms in the Oregon Coast Range

    NASA Astrophysics Data System (ADS)

    Marshall, J. A.; Roering, J. J.

    2010-12-01

    convexity. These findings suggest that production mechanisms on rapidly eroding slopes are tightly coupled with multiple stochastic physical weathering processes acting on bedrock, while in slower eroding terrain, physical weathering processes, particularly root disturbances, have minimal interaction with bedrock. On the ridges with the most negative curvature values (~-0.1 to -0.15), we find variable soil depth (7 to 91 cm). On rapidly eroding slopes, physical mechanisms for bedrock to soil conversion appear to include exfoliation of thin curved lenses of bedrock, root upheaval of fractured bedrock slabs, and mixing of weathered bedrock and soil via tree turnover. On intermediate curvature slopes, we observe less variability in depth to bedrock, and evidence for abiotic physical controls on soil production weakens. On slow eroding ridges (curvature values ~ -0.003 to -0.012), soil depths ranged from 90 to over 150 cm, with no root-bedrock contact. We find no evidence of exfoliation, competent saprolite or bedrock; and large clasts are extremely rare in the well-mixed soils on slow eroding ridges. We speculate that in rapidly eroding settings, tree size and spacing dictate biotic control on bedrock to soil conversion, while abiotic weathering depends on exfoliation rates for unfractured rock.

  20. Reduced tillage and cover crops as a strategy for mitigating atmospheric CO2 increase through soil organic carbon sequestration in dry Mediterranean agroecosystems.

    NASA Astrophysics Data System (ADS)

    Almagro, María; Garcia-Franco, Noelia; de Vente, Joris; Boix-Fayos, Carolina; Díaz-Pereira, Elvira; Martínez-Mena, María

    2016-04-01

    The implementation of sustainable land management (SLM) practices in semiarid Mediterranean agroecosystems can be beneficial to maintain or enhance levels of soil organic carbon and mitigate current atmospheric CO2 increase. In this study, we assess the effects of different tillage treatments (conventional tillage (CT), reduced tillage (RT), reduced tillage combined with green manure (RTG), and no tillage (NT)) on soil CO2 efflux, aggregation and organic carbon stabilization in two semiarid organic rainfed almond (Prunus dulcis Mill., var. Ferragnes) orchards located in SE Spain Soil CO2 efflux, temperature and moisture were measured monthly between May 2012 and December 2014 (site 1), and between February 2013 and December 2014 (site 2). In site 1, soil CO2 efflux rates were also measured immediately following winter and spring tillage operations. Aboveground biomass inputs were estimated at the end of the growing season in each tillage treatment. Soil samples (0-15 cm) were collected in the rows between the trees (n=4) in October 2012. Four aggregate size classes were distinguished by sieving (large and small macroaggregates, free microaggregates, and free silt plus clay fraction), and the microaggregates occluded within macroaggregates (SMm) were isolated. Soil CO2efflux rates in all tillage treatments varied significantly during the year, following changes during the autumn, winter and early spring, or changes in soil moisture during late spring and summer. Repeated measures analyses of variance revealed that there were no significant differences in soil CO2 efflux between tillage treatments throughout the study period at both sites. Average annual values of C lost by soil respiration were slightly but not significantly higher under RT and RTG treatments (492 g C-CO2 m-2 yr-1) than under NT treatment (405 g C-CO2 m-2 yr-1) in site 1, while slightly but not significantly lower values were observed under RT and RTG treatments (468 and 439 g C-CO2 m-2 yr-1

  1. Profiling soil water content sensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A waveguide-on-access-tube (WOAT) sensor system based on time domain reflectometry (TDR) principles was developed to sense soil water content and bulk electrical conductivity in 20-cm (8 inch) deep layers from the soil surface to depths of 3 m (10 ft) (patent No. 13/404,491 pending). A Cooperative R...

  2. 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.

  3. 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.

  4. 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.

  5. On the study of Structural properties and Cation distribution of Zn0.75-xNixMg0.15Cu0.1Fe2O4 nano ferrite: Effect of Ni addition

    NASA Astrophysics Data System (ADS)

    Satalkar, M.; Kane, S. N.

    2016-10-01

    Effect of Ni addition on structural properties and, cation distribution of Zn0.75-xNixMg0.15Cu0.1Fe2O4 (x = 0.0, 0.15, 0.30, 0.60, 0.75) ferrites, prepared using sol-gel autocombustion method was studied using X-ray diffraction (XRD) technique. XRD analysis reveals the formation of spinel phase even in dry gel form. The lattice constant (a exp.) decreases with Ni2+ substitution and follows Vegard's law. Scherrer's grain diameter (D) lies within the range of 17.33 - 26.47 nm. Due to difference in the ionic radii of Zn2+ and Ni2+ significant changes are observed in the structural parameters - unit cell volume (V), hopping length at A (La ) and B (Lb ) site, and x-ray density (ρXRD ). Linear increase in Neel magnetic moment (nB N) with oxygen positional parameter is observed in the studied samples, attributed to simultaneous weakening of A-B interaction and strengthening of the B-B interaction.

  6. A combined sol-gel and spark plasma sintering route to produce highly dense and fine-grained La0.65Ca0.20Na0.15MnO3 ceramics for magnetocaloric applications

    NASA Astrophysics Data System (ADS)

    Abdallah-Ben Ammar, Amal; Ayadi, Firas; Nowak, Sophie; Lecoq, Hélène; Cheikrouhou-Koubaa, Wissem; Cheikhrouhou, Abdelwaheb; Ammar, Souad; Sicard, Lorette

    2014-03-01

    Sol-gel chemistry and spark plasma sintering were coupled to produce fine-grained and dense La0.65Ca0.20Na0.15MnO3 ceramics and their magnetic properties were explored in order to evaluate their efficiency for domestic magnetocaloric applications. The obtained manganites crystallize in the rhombohedral symmetry (R-3c). They present grain size in the sub-micrometer range. Their density and their average grain size increase when the sintering temperature increases from 600 to 800 °C. This entails an increase of the Curie temperature (T C) and of the maximum of the magnetic entropy change, even if these values remain smaller than those measured on their bulk counterparts prepared by a conventional solid state route. However, the magnetic transition occurs on a broad temperature range, resulting in a relative cooling power reaching about 265 J Kg-1 for an applied magnetic field of 5 T. This value is very close to that previously measured on bulk La0.65Ca0.20Na0.15MnO3 ceramics and represents about 64% of that measured on the standard Gd. The ceramics produced here by a low-energy and time-consuming method can thus be considered as technically and economically valuable for the desired applications.

  7. Spectra of circular and linear photogalvanic effect at inter-band excitation in In0.15Ga0.85As/Al0.3Ga0.7As multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Yu, Jinling; Chen, Yonghai; Cheng, Shuying; Lai, Yunfeng

    2013-03-01

    Spectra of circular photogalvanic effect (CPGE) and linear photogalvanic effect (LPGE) for inter-band transition have been experimentally investigated in In0.15Ga0.85As/Al0.3Ga0.7As multiple quantum wells (QWs) at room temperature. The CPGE and LPGE spectra are quite similar during the spectral region corresponding to the transitions 1e1hh (the first valence subband of heavy hole to the first conduction band) and 1e2hh, which is also similar to that of the photoconductivity. Comparing the photocurrent induced by LPGE and CPGE along [1 1 0] and [1 1bar 0] directions, we obtain the anisotropic ratio of the linear photogalvanic tensor χ and circular photogalvanic tensor γ to be χxxz/χyyz=3.6 and γxy/γyx=1.3 (x∥[1 1 0] and y∥[1 1bar 0]), which indicate that the symmetry of the structure belongs to C2v point group and the Rashba spin splitting is the dominant mechanism to induce the k-linear spin splitting of the subband in the In0.15Ga0.85As/Al0.3Ga0.7As QWs. The magnitude of the LPGE is nearly at the same order with that of the CPGE for the investigated spectral region at room temperature.

  8. Sub-cm Particles in Saturn's Rings from VIMS, UVIS, and RSS occultations

    NASA Astrophysics Data System (ADS)

    Jerousek, Richard Gregory; Colwell, Josh E.; Hedman, Matthew M.; Marouf, Essam A.; Esposito, Larry W.; Nicholson, Philip D.; French, Richard G.

    2016-10-01

    Particles sizes in Saturn's rings roughly follow a truncated power law. One way to determine the governing parameters of the size distribution is through the analysis of differential optical depths (Zebker et al. 1983). Non-axisymmetric self-gravity wakes complicate this approach when optical depth measurements at different wavelengths are not made at same viewing geometry. Using occultations spanning a wide range of viewing angles and from multiple instruments onboard Cassini (the Ultraviolet Imaging Spectrograph (UVIS), the Visual and Infrared Mapping Spectrometer (VIMS), and the Radio Science Subsystem (RSS)), we forward-model the properties of the self-gravity wakes in Saturn's A and B rings while simultaneously constraining the parameters of the cm - sub-cm particle size distribution. In the absence of wakes, and in regions where particles smaller than ~ 8.86 mm are present, VIMS stellar occultations measure larger optical depths than UVIS stellar occultations due to the diffraction of 2.9 μm light out of the small (0.25 × 0.5 mrad) VIMS field of view compared with UVIS which measures shorter wavelength (0.15 μm) light over a much larger (6.4 × 6.0 mrad) field of view. This excess optical depth combined with RSS X-band (λ = 3.6 cm) optical depths provides a way to probe both the power law slope and the minimum particle size. In the A and B rings where self-gravity wakes are prevalent, we use the wake model of Colwell et al. (2006, 2007) with an additional free parameter representing the excess optical depth which would be measured through the gaps between opaque wakes, by VIMS compared to UVIS. In the B ring and inner A ring we find and absence of sub-cm particles and power law slopes of q ~ 2.8. In the trans-Encke region, where there are a multitude of satellite driven resonances, we find an increasing abundance of sub-cm particles as the outer edge of the A ring is approached. In the C Ring and the Cassini Division, where self-gravity wakes are absent

  9. Microwave remote sensing of soil water content

    NASA Technical Reports Server (NTRS)

    Cihlar, J.; Ulaby, F. T.

    1975-01-01

    Microwave remote sensing of soils to determine water content was considered. A layered water balance model was developed for determining soil water content in the upper zone (top 30 cm), while soil moisture at greater depths and near the surface during the diurnal cycle was studied using experimental measurements. Soil temperature was investigated by means of a simulation model. Based on both models, moisture and temperature profiles of a hypothetical soil were generated and used to compute microwave soil parameters for a clear summer day. The results suggest that, (1) soil moisture in the upper zone can be predicted on a daily basis for 1 cm depth increments, (2) soil temperature presents no problem if surface temperature can be measured with infrared radiometers, and (3) the microwave response of a bare soil is determined primarily by the moisture at and near the surface. An algorithm is proposed for monitoring large areas which combines the water balance and microwave methods.

  10. Fine root dynamics for forests on contrasting soils in the Colombian Amazon

    NASA Astrophysics Data System (ADS)

    Jiménez, E. M.; Moreno, F. H.; Peñuela, M. C.; Patiño, S.; Lloyd, J.

    2009-12-01

    It has been hypothesized that as soil fertility increases, the amount of carbon allocated to below-ground production (fine roots) should decrease. To evaluate this hypothesis, we measured the standing crop fine root mass and the production of fine roots (<2 mm) by two methods: (1) ingrowth cores and, (2) sequential soil coring, during 2.2 years in two lowland forests growing on different soils types in the Colombian Amazon. Differences of soil resources were defined by the type and physical and chemical properties of soil: a forest on clay loam soil (Endostagnic Plinthosol) at the Amacayacu National Natural Park and, the other on white sand (Ortseinc Podzol) at the Zafire Biological Station, located in the Forest Reservation of the Calderón River. We found that the standing crop fine root mass and the production was significantly different between soil depths (0-10 and 10-20 cm) and also between forests. The loamy sand forest allocated more carbon to fine roots than the clay loam forest with the production in loamy sand forest twice (mean±standard error=2.98±0.36 and 3.33±0.69 Mg C ha-1 yr-1, method 1 and 2, respectively) as much as for the more fertile loamy soil forest (1.51±0.14, method 1, and from 1.03±0.31 to 1.36±0.23 Mg C ha-1 yr-1, method 2). Similarly, the average of standing crop fine root mass was higher in the white-sands forest (10.94±0.33 Mg C ha-1) as compared to the forest on the more fertile soil (from 3.04±0.15 to 3.64±0.18 Mg C ha-1). The standing crop fine root mass also showed a temporal pattern related to rainfall, with the production of fine roots decreasing substantially in the dry period of the year 2005. These results suggest that soil resources may play an important role in patterns of carbon allocation to the production of fine roots in these forests as the proportion of carbon allocated to above- and below-ground organs is different between forest types. Thus, a trade-off between above- and below-ground growth seems to exist

  11. Prediction of soil organic carbon concentration and soil bulk density of mineral soils for soil organic carbon stock estimation

    NASA Astrophysics Data System (ADS)

    Putku, Elsa; Astover, Alar; Ritz, Christian

    2016-04-01

    Soil monitoring networks provide a powerful base for estimating and predicting nation's soil status in many aspects. The datasets of soil monitoring are often hierarchically structured demanding sophisticated data analyzing methods. The National Soil Monitoring of Estonia was based on a hierarchical data sampling scheme as each of the monitoring site was divided into four transects with 10 sampling points on each transect. We hypothesized that the hierarchical structure in Estonian Soil Monitoring network data requires a multi-level mixed model approach to achieve good prediction accuracy of soil properties. We used this database to predict soil bulk density and soil organic carbon concentration of mineral soils in arable land using different statistical methods: median approach, linear regression and mixed model; additionally, random forests for SOC concentration. We compared the prediction results and selected the model with the best prediction accuracy to estimate soil organic carbon stock. The mixed model approach achieved the best prediction accuracy in both soil organic carbon (RMSE 0.22%) and bulk density (RMSE 0.09 g cm-3) prediction. Other considered methods under- or overestimated higher and lower values of soil parameters. Thus, using these predictions we calculated the soil organic carbon stock of mineral arable soils and applied the model to a specific case of Tartu County in Estonia. Average estimated SOC stock of Tartu County is 54.8 t C ha-1 and total topsoil SOC stock 1.8 Tg in humus horizon.

  12. CARBON SEQUESTRATION IN RECLAIMED MINED SOILS OF OHIO

    SciTech Connect

    M.K. Shukla; R. Lal

    2005-04-01

    Assessment of soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS) is important for preserving environmental quality and increasing agronomic yields. The mechanism of physical SOC sequestration is achieved by encapsulation of SOM in spaces within macro and microaggregates. The experimental sites, owned and maintained by American Electrical Power, were characterized by distinct age chronosequences of reclaimed minesoils and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites were reclaimed both with and without topsoil application, and were under continuous grass or forest cover. In this report results are presented from the sites reclaimed in 2003 (R03-G), in 1973 (R73-F), in 1969 (R69-G), in 1962 (R62-G and R62-F) and in 1957 (R57-F). Three sites are under continuous grass cover and the three under forest cover since reclamation. Three bulk soil samples were collected from each site from three landscape positions (upper; middle, and lower) for 0-15 and 15-30 cm depths. The samples were air dried and using wet sieving technique were fractionated into macro (> 2mm), meso (2-0.25 mm) and microaggregate (0.25-0.053 mm). These fractions were weighted separately and water stable aggregation (WSA) and geometric mean (GMD) and mean weight (MWD) diameters of aggregates were obtained. The soil C and N concentrations were also determined on these aggregate fractions. Analysis of mean values showed that in general, WSA and MWD of aggregates increased with increasing duration since reclamation or age of reclaimed soil for all three landscape positions and two depths in sites under continuous grass. The forest sites were relatively older than grass sites and therefore WSA or MWD of aggregates did not show any increases with age since reclamation. The lower WSA in R57-F site than R73-F clearly showed the effect of soil erosion on aggregate stability. Higher aggregation and aggregate diameters in R73-F than R62-F and R57

  13. 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.

  14. 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.

  15. Alteration and formation of rims on the CM parent body

    NASA Astrophysics Data System (ADS)

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

    1994-03-01

    All types of coarse-grained components in CM chondrites are surrounded by fine-grained dust coatings, but the origin of these rims is not yet clear. Although a strictly nebular origin seems likely for rims in the relatively unaltered type 3 chondrites, the rims in CM chondrites are dominated by secondary alteration phases. It has been argued that either the coarse-grained cores accreted altered rim materials while still in the nebula or that alteration of primary rim phases occurred on the CM parent body. To constrain the origin of alteration phases in rim material, we have analyzed the textures and mineral associations from 10 CM chondritic falls by optical and scanning electron microscopy. Our results indicate that the secondary phases in CM chondritic rims were produced by parent body fluid-rock interactions which redefined some primary rim textures and may have produced, in some cases, both coarse-grained components and the rims that surround them. Textural features demonstrate the interactive exchange of alteration fluids between rims, matrix, and chondrules on the CM parent body. For example, most matrix-rim contacts are gradational, suggesting the synchronous alteration of both components. Several observations suggest the possibility of in situ rim production. For example, tochilinite and phyllosilicates commonly form rims around matrix carbonates, which are generally believed to have precipitated from alteration fluids on the CM parent body. This suggests that the rims surrounding matrix carbonates may also have been produced by alteration processes. Partially replaced chondrule olivines bear a striking resemblance to many rimmed olivines in the matrix which suggests, by analogy, that site-specific precipitation of S-bearing phases may also be responsible for the occurrence of many tochilinite-rich rims around isolated matrix olivines. Non-silicate rims precipitate around olivines of any composition, but the process is most effective for fayalitic olivines

  16. The impact of soil compaction and freezing-thawing cycles on soil structure and yield in Mollisol region of China

    NASA Astrophysics Data System (ADS)

    Wang, Enheng; Zhao, Yusen; Chen, Xiangwei

    2015-04-01

    Agricultural machinery tillage and alternating freezing and thawing are two critical factors associated with soil structure change and accelerates soil erosion in the black soil region of Northeast China. Combining practical machinery operation and natural freeze-thaw cycles with artificial machinery compaction in the field and artificial freeze-thaw cycles in the lab, the plus and minus benefits of machinery tillage, characterization of seasonal freeze-thaw cycles, and their effects on soil structure and yield were studied. Firstly,the effects of machinery type and antecedent water content on soil structure and soil available nutrient were investigated by measuring soil bulk density, soil strength, soil porosity, soil aggregate distribution and stability, and three soil phases. The results showed that: Machinery tillage had positive and negative influence on soil structure, soil in top cultivated layer can be loosened and ameliorated however the subsoil accumulation of compaction was resulted. For heavy and medium machinery, subsoil compaction formed in the soil depth of 41~60cm and 31~40cm, respectively; however during the soil depth of 17.5~30cm under medium machinery operation there was a new plow pan produced because of the depth difference between harvesting and subsoiling. Antecedent water content had a significant effect on soil structure under machinery operations. Higher water antecedent resulted in deeper subsoil compaction at 40cm,which was deeper by 10cm than lower water content and soil compaction accumulation occurred at the first pass under higher water content condition. Besides water content and bulk density, soil organic matter is another key factor for affecting compressive-resilient performance of tillage soil. Secondly, based on the soils sampled from fields of the black soil region, the effects of freeze-thaw cycles on soil structure at different soil depths (0 -- 40 cm, 40 -- 80 cm, 120 -- 160 cm) and size scales (field core sampling

  17. Laboratory Experiment on Electrokinetic Remediation of Soil

    ERIC Educational Resources Information Center

    Elsayed-Ali, Alya H.; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E.

    2011-01-01

    Electrokinetic remediation is a method of decontaminating soil containing heavy metals and polar organic contaminants by passing a direct current through the soil. An undergraduate chemistry laboratory is described to demonstrate electrokinetic remediation of soil contaminated with copper. A 30 cm electrokinetic cell with an applied voltage of 30…

  18. An Infiltration Exercise for Introductory Soil Science

    ERIC Educational Resources Information Center

    Barbarick, K. A.; Ippolito, J. A.; Butters, G.; Sorge, G. M.

    2005-01-01

    One of the largest challenges in teaching introductory soil science is explaining the dynamics of soil infiltration. To aid students in understanding the concept and to further engage them in active learning in the soils laboratory course, we developed an exercise using Decagon Mini-Disk Infiltrometers with a tension head (h[subscript o]) of 2 cm.…

  19. High technology biomass production by Salix clones on a sandy soil in southern Sweden.

    PubMed

    Christersson, Lars

    1986-12-01

    An investigation was undertaken to (1) determine maximum biomass production of fast-growing Salix clones on dry or nutrient-deficient land where adequate nutrients and water are supplied by irrigation and fertilization, (2) compare the efficiency of different irrigation-fertilization systems, (3) investigate the possibilities of successively increasing soil fertility by a fertilization routine adjusted to growth and uptake, (4) monitor the leakage of different nutrients to groundwater, and (5) make economic calculations with respect to the different irrigation-fertilization systems. The experimental area, which was abandoned farmland, was planted in 1982 with clones of Salix. The soil was very sandy with small amounts of organic matter. The groundwater table was 2-3 m deep. The pH of the soil at 0-15 cm depth was initially 4.8-5.5. Three irrigation-fertilization systems were used: (1) drip, (2) sprinklers, and (3) subsurface irrigation. During summer 1984, the area was irrigated and fertilized once a week for 12 weeks with a complete liquid fertilizer equivalent to 10 kg N per week. Production was about 1 kg m(-2) and 3 kg m(-2) for 1- and 2-year-old shoots, respectively. There were no significant differences between the irrigation-fertilization systems or between the species and clones, for either 1- or 2-year-old shoots.

  20. Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil

    USGS Publications Warehouse

    Borken, W.; Davidson, E.A.; Savage, K.; Sundquist, E.T.; Steudler, P.

    2006-01-01

    Soil moisture strongly controls the uptake of atmospheric methane by limiting the diffusion of methane into the soil, resulting in a negative correlation between soil moisture and methane uptake rates under most non-drought conditions. However, little is known about the effect of water stress on methane uptake in temperate forests during severe droughts. We simulated extreme summer droughts by exclusion of 168 mm (2001) and 344 mm (2002) throughfall using three translucent roofs in a mixed deciduous forest at the Harvard Forest, Massachusetts, USA. The treatment significantly increased CH4 uptake during the first weeks of throughfall exclusion in 2001 and during most of the 2002 treatment period. Low summertime CH4 uptake rates were found only briefly in both control and exclusion plots during a natural late summer drought, when water contents below 0.15 g cm-3 may have caused water stress of methanotrophs in the A horizon. Because these soils are well drained, the exclusion treatment had little effect on A horizon water content between wetting events, and the effect of water stress was smaller and more brief than was the overall treatment effect on methane diffusion. Methane consumption rates were highest in the A horizon and showed a parabolic relationship between gravimetric water content and CH4 consumption, with maximum rate at 0.23 g H2O g-1 soil. On average, about 74% of atmospheric CH4 was consumed in the top 4-5 cm of the mineral soil. By contrast, little or no CH4 consumption occurred in the O horizon. Snow cover significantly reduced the uptake rate from December to March. Removal of snow enhanced CH4 uptake by about 700-1000%, resulting in uptake rates similar to those measured during the growing season. Soil temperatures had little effect on CH4 uptake as long as the mineral soil was not frozen, indicating strong substrate limitation of methanotrophs throughout the year. Our results suggest that the extension of snow periods may affect the annual rate

  1. 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.

  2. The 21-cm Signal from the cosmological epoch of recombination

    SciTech Connect

    Fialkov, A.; Loeb, A. E-mail: aloeb@cfa.harvard.edu

    2013-11-01

    The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies.

  3. CM Process Improvement and the International Space Station Program (ISSP)

    NASA Technical Reports Server (NTRS)

    Stephenson, Ginny

    2007-01-01

    This viewgraph presentation reviews the Configuration Management (CM) process improvements planned and undertaken for the International Space Station Program (ISSP). It reviews the 2004 findings and recommendations and the progress towards their implementation.

  4. Orion Landing Simulation Eight Soil Model Comparison

    NASA Technical Reports Server (NTRS)

    Mark, Stephen D.

    2009-01-01

    LS-DYNA finite element simulations of a rigid Orion Crew Module (CM) were used to investigate the CM impact behavior on eight different soil models. Ten different landing conditions, characterized by the combination of CM vertical and horizontal velocity, hang angle, and roll angle were simulated on the eight different soils. The CM center of gravity accelerations, pitch angle, kinetic energy, and soil contact forces were the outputs of interest. The simulation results are presented, with comparisons of the CM behavior on the different soils. The soils analyzed in this study can be roughly categorized as soft, medium, or hard, according to the CM accelerations that occur when landing on them. The soft group is comprised of the Carson Sink Wet soil and the Kennedy Space Center (KSC) Low Density Dry Sand. The medium group includes Carson Sink Dry, the KSC High Density In-Situ Moisture Sand and High Density Flooded Sand, and Cuddeback B. The hard soils are Cuddeback A and the Gantry Unwashed Sand. The softer soils were found to produce lower peak accelerations, have more stable pitch behavior, and to be less sensitive to the landing conditions. This investigation found that the Cuddeback A soil produced the highest peak accelerations and worst stability conditions, and that the best landing performance was achieved on the KSC Low Density Dry Sand.

  5. Soils and the soil cover of the Valley of Geysers

    NASA Astrophysics Data System (ADS)

    Kostyuk, D. N.; Gennadiev, A. N.

    2014-06-01

    The results of field studies of the soil cover within the tourist part of the Valley of Geysers in Kamchatka performed in 2010 and 2011 are discussed. The morphology of soils, their genesis, and their dependence on the degree of hydrothermal impact are characterized; the soil cover patterns developing in the valley are analyzed. On the basis of the materials provided by the Kronotskii Biospheric Reserve and original field data, the soil map of the valley has been developed. The maps of vegetation conditions, soil temperature at the depth of 15 cm, and slopes of the surface have been used for this purpose together with satellite imagery and field descriptions of reference soil profiles. The legend to the soil map includes nine soil units and seven units of parent materials and their textures. Soil names are given according to the classification developed by I.L. Goldfarb (2005) for the soils of hydrothermal fields. The designation of soil horizons follows the new Classification and Diagnostic System of Russian Soils (2004). It is suggested that a new horizon—a thermometamorphic horizon TRM—can be introduced into this system by analogy with other metamorphic (transformed in situ) horizons distinguished in this system. This horizon is typical of the soils partly or completely transformed by hydrothermal impacts.

  6. Application of magnetic methods for assessment of soil restoration in the vicinity of metallurgical copper-processing plant in Bulgaria.

    PubMed

    Jordanova, N; Petrovský, E; Kapicka, A; Jordanova, D; Petrov, P

    2017-04-01

    Copper ore mining and processing are among the most harmful anthropogenic influences for the environment and they are a subject of international and national law regulations. Recultivation of areas influenced by mining and processing industry is commonly applied and monitored in order to restore as much as possible the natural environment. In this study, environmental magnetic methods are applied in order to assess the degree of soil restoration in terms of soil development, after remediation of waste dump from Cu-processing plant. Soils developed under birch forest stands of different age (5, 15, and 25 years) as well as raw waste material were sampled along depth down to 20-30 cm. Variations in magnetic parameters and ratios obtained (magnetic susceptibility, frequency-dependent magnetic susceptibility, anhysteretic remanence (ARM), isothermal remanence (IRM), ARM/IRM100mT) suggest the presence of magnetic enhancement in the upper 0-15 cm, the thickness of this layer varying depending on the age of the forest stand. Magnetic mineral responsible for this enhancement is of magnetite type, while waste material contains a large amount of hematite, as evidenced by coercivity analysis of IRM acquisition curves and thermal demagnetization of composite IRM. Magnetic grain-sized proxy parameters suggest that magnetite particles are coarser, magnetically stable, while no or minor amount of superparamagnetic grains were detected at room temperature. A well-defined linear regression between the topsoil magnetic susceptibility and the approximate age of the forest stand provides an indication that the magnetic enhancement is of pedogenic origin. It is concluded that the observed magnetic enhancement of recultivated soils studied is linked to a combined effect of pedogenic contribution and possible additions of industrial ashes as a liming agent for soil restoration.

  7. Risk of Malignancy in Thyroid Nodules 4 cm or Larger

    PubMed Central

    2017-01-01

    Background Several authors have questioned the accuracy of fine-needle aspiration cytology (FNAC) in large nodules. Some surgeons recommend thyroidectomy for nodules ≥4 cm even in the setting of benign FNAC, due to increased risk of malignancy and increased false negative rates in large thyroid nodules. The goal of our study was to evaluate if thyroid nodule size is associated with risk of malignancy, and to evaluate the false negative rate of FNAC for thyroid nodules ≥4 cm in our patient population. Methods This is a retrospective study of 85 patients with 101 thyroid nodules, who underwent thyroidectomy for thyroid nodules measuring ≥4 cm. Results The overall risk of malignancy in nodules ≥4 cm was 9.9%. Nodule size was not associated with risk of malignancy (odds ratio, 1.02) after adjusting for nodule consistency, age, and sex (P=0.6). The false negative rate for FNAC was 0%. Conclusion Nodule size was not associated with risk of malignancy in nodules ≥4 cm in our patient population. FNAC had a false negative rate of 0. Patients with thyroid nodules ≥4 cm and benign cytology should not automatically undergo thyroidectomy. PMID:28181427

  8. Neutron-Spin Resonance in the Optimally Electron-Doped Superconductor Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4-{delta}}

    SciTech Connect

    Zhao Jun; Li Shiliang; Dai Pengcheng; Freeman, Paul G.; Onose, Y.; Tokura, Y.

    2007-07-06

    We use inelastic neutron scattering to probe magnetic excitations of an optimally electron-doped superconductor Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4-{delta}} above and below its superconducting transition temperature T{sub c}=25 K. In addition to gradually opening a spin pseudogap at the antiferromagnetic ordering wave vector Q=(1/2,1/2,0), the effect of superconductivity is to form a resonance centered also at Q=(1/2,1/2,0) but at energies above the spin pseudogap. The intensity of the resonance develops like a superconducting order parameter, similar to those for hole-doped superconductors and electron-doped Pr{sub 0.88}LaCe{sub 0.12}CuO{sub 4}. The resonance is therefore a general phenomenon of cuprate superconductors, and must be fundamental to the mechanism of high-T{sub c} superconductivity.

  9. Resonance in Optimally Electron-Doped Superconductor Nd1.85Ce0.15CuO4−?

    SciTech Connect

    Zhao, Jun; Dai, Pengcheng; Li, Shiliang; Freeman, Paul G.; Onose, Y,.; Tokura, Y.

    2007-01-01

    We use inelastic neutron scattering to probe magnetic excitations of an optimally electron-doped superconductor Nd1.85Ce0.15CuO4− above and below its superconducting transition temperature Tc = 25 K. In addition to gradually opening a spin pseudo gap at the antiferromagnetic ordering wavevector Q = (1/2, 1/2, 0), the effect of superconductivity is to form a resonance centered also at Q = (1/2, 1/2, 0) but at energies above the spin pseudo gap. The intensity of the resonance develops like a superconducting order parameter, similar to those for hole-doped superconductors and electron-doped Pr0.88LaCe0.12CuO4. The resonance is therefore a general phenomenon of cuprate superconductors, and must be fundamental to the mechanism of high-Tc superconductivity.

  10. 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.

  11. 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.

  12. Degradation of hydration kinetics of proton-conducting Ba(Zr0.84Y0.15Cu0.01)O3-δ during conductivity-relaxation experiment

    NASA Astrophysics Data System (ADS)

    Choi, Sung Min; Lee, Jong-Heun; Hong, Jongsup; Yoon, Kyung Joong; Son, Ji-Won; Kim, Byung-Kook; Lee, Hae-Weon; Lee, Jong-Ho

    2016-11-01

    The chemical-diffusion and surface-exchange coefficients of a proton-conducting oxide, i.e., Ba(Zr0.84Y0.15Cu0.01)O3-δ upon a sudden change of water-vapor pressure at a fixed oxygen partial pressure are investigated via a conductivity relaxation technique. Conductivity relaxation during the hydration/dehydration process follows typical two-fold non-monotonic behavior that can be explained by decoupled chemical diffusion of H and O. However, the temperature dependence of the measured chemical-diffusion and surface-exchange coefficients is significantly different depending on the direction of the temperature change. In this study, we attempt to identify the origin of these unusual behaviors during the conductivity relaxation experiment via thorough microstructural and compositional analyses on sample surface.

  13. 63Cu nuclear magnetic resonance study of Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4): Ni-induced spin density oscillation and modification of the low energy spin fluctuations.

    PubMed

    Williams, G V M; Jurkutat, M; Rybicki, D; Haase, J

    2011-02-23

    We report the results from a (63)Cu nuclear magnetic resonance (NMR) study of the electron-doped high temperature superconducting cuprate (HTSC) Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4). We find that Ni induces a magnetic broadening of the (63)Cu NMR spectra that can be interpreted in terms of an induced spin density oscillation about the Ni site, similar to that reported from (63)Cu NMR measurements on the hole-doped HTSCs when Zn is partially substituted for Cu. There is also an additional temperature-dependent contribution to the (63)Cu spin-lattice relaxation rate that can be interpreted in terms of an Ni-induced modification of the low energy spin fluctuations. Furthermore, the spin fluctuations are intrinsically spatially inhomogeneous and additional inhomogeneities are induced by Ni.

  14. F19 NMR study of the coupling between 4f and itinerant electrons in the pnictide superconductors SmFeAsO1-xFx (0.15≤x≤0.2)

    NASA Astrophysics Data System (ADS)

    Prando, G.; Carretta, P.; Rigamonti, A.; Sanna, S.; Palenzona, A.; Putti, M.; Tropeano, M.

    2010-03-01

    F19 NMR measurements in SmFeAsO1-xFx , for 0.15≤x≤0.2 , are presented. The nuclear spin-lattice relaxation rate 1/T1 increases upon cooling with a trend analogous to the one already observed in CeCu5.2Au0.8 , a quasi-two-dimensional heavy-fermion intermetallic compound with an antiferromagnetic ground state. In particular, the behavior of the relaxation rate either in SmFeAsO1-xFx or in CeCu5.2Au0.8 can be described in the framework of the self-consistent renormalization theory for weakly itinerant electron systems. Remarkably, no effect of the superconducting transition on F19 1/T1 is detected, a phenomenon which can hardly be explained within a single band model.

  15. The ageing and de-ageing behaviour of (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 lead-free piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Zhang, Yichi; Glaum, Julia; Ehmke, Matthias C.; Bowman, Keith J.; Blendell, John E.; Hoffman, Mark J.

    2015-09-01

    Ageing behaviour usually occurs in acceptor-doped piezoelectric materials (e.g., hard lead zirconate titanate) and exhibits the development of a pinched or shifted hysteresis loop over time. Although no pinched hysteresis loop was observed for lead-free (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 material, this study showed that the piezoelectric properties change over time in the poled state. The shift of the hysteresis loop along the electric field axis and the development of asymmetry in strain and permittivity hysteresis loop were observed during the ageing process. The origin of this ageing behaviour is proposed to be local defect dipoles and the migration of the charged defects to the grain boundaries. The reorientation of the defect dipole contributes to a fast but unstable ageing mechanism in this material while the migration of the charged defects contributes to a slow but more stable mechanism.

  16. 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).

  17. Two regimes behavior in the resistivity of the La 1.85Sr 0.15Cu 1- xLi xO 4 system: A signature of different electronic states for holes

    NASA Astrophysics Data System (ADS)

    García, S.; Musa, J. E.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    1998-01-01

    The variations of the normal-state resistivity and the superconducting transition temperature Tc of the La 1.85Sr 0.15(Cu 1- xLi x)O 4 system for 0 ≤ x ≤ 0.05 reveal a two regimes behavior, with x ≅ 0.03 being the critical concentration for a transition from a delocalized state, with a reduction of the resistivity values while Tc remains unchanged, to an early stage of a spin compensation process, characterized by Tc suppression without broadening. Disorder at the CuO 2 planes is proposed to be the source of localization and Tc depletion, as supported by fitting of the normal-state curves according to different conduction models.

  18. Normal-state magnetic properties and their correlation with Tc suppression and the resistivity anomalies in the (La1-xPrx)1.85Sr0.15CuO4 series

    NASA Astrophysics Data System (ADS)

    Musa, J. E.; García, S.; Rothier de Amaral, M.; Salim de Amorim, H.; Giordanengo, B.; Baggio-Saitovitch, E. M.; Pagliuso, P. J. G.; Rettori, C.; Yelon, W. B.; Malik, S. K.

    1999-04-01

    We have investigated the normal-state anomalies observed in the magnetic and transport properties of the (La1-xPrx)1.85Sr0.15CuO4 system with 0⩽x⩽0.5. The resistivity curves showed an increasing deviation from linearity below ˜100 K. This behavior is properly accounted by a logarithmic term, whose coefficient C linearly increases with x. The normal-state magnetic susceptibility measurements evidenced a departure from the Pr3+ Curie-Weiss dependence in the same temperature range for which the resistivity anomaly occurs. A comprehensive picture of the conduction mechanism is presented in terms of a Kondo-like scattering of the mobile holes by the spin fluctuations.

  19. Electrical transport and giant magnetoresistance in La0.75Sr0.25Mn1-xCrxO3 (0.15, 0.20 and 0.25) manganite oxide.

    PubMed

    Dhahri, Ah; Jemmali, M; Dhahri, E; Hlil, E K

    2015-03-28

    We have investigated the influence of chromium (Cr) doping on the magneto-electrical properties of polycrystalline samples La0.75Sr0.25Mn1-xCrxO3 (0.15 ≤ x ≤ 0.25), prepared by the sol-gel method. Comparison of experimental data with the theoretical models shows that in the metal-ferromagnetic region, the electrical behavior of the three samples is quite well described by a theory based on electron-electron, electron-phonon and electron-magnon scattering and Kondo-like spin dependent scattering. For the high temperature paramagnetic insulating regime, the adiabatic small polaron hopping (SPH) model is found to fit well the experimental curves.

  20. 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.

  1. Evaluation on residual stress in Bi3.15(Eu0.7Nd0.15)Ti3O12 polycrystalline ferroelectric thin film by using the orientation average method

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Cheng, H. B.; Wang, X. Y.; Zheng, X. J.

    2012-12-01

    We propose an orientation average method to evaluate residual stresses in polycrystalline thin films. Bi3.15(Eu0.7Nd0.15)Ti3O12 was used to verify our approach, with films prepared by metal organic decomposition at various annealing temperatures. The mechanical properties and microstructure were characterized by nanoindentation and X-ray diffraction. The thin film annealed at 600 °C has the largest residual compressive stress of 771 MPa among all thin films. The residual stresses are evaluated by the proposed method and traditional sin2ψ method, and the maximum distinction is less than 6.43%, demonstrating that the proposed method is reliable and convenient to evaluate residual stress in polycrystalline thin films.

  2. Highly CO2-Tolerant Cathode for Intermediate-Temperature Solid Oxide Fuel Cells: Samarium-Doped Ceria-Protected SrCo0.85Ta0.15O3-δ Hybrid.

    PubMed

    Li, Mengran; Zhou, Wei; Zhu, Zhonghua

    2017-01-25

    Susceptibility to CO2 is one of the major challenges for the long-term stability of the alkaline-earth-containing cathodes for intermediate-temperature solid oxide fuel cells. To alleviate the adverse effects from CO2, we incorporated samarium-stabilized ceria (SDC) into a SrCo0.85Ta0.15O3-δ (SCT15) cathode by either mechanical mixing or a wet impregnation method and evaluated their cathode performance stability in the presence of a gas mixture of 10% CO2, 21% O2, and 69% N2. We observed that the CO2 tolerance of the hybrid cathode outperforms the pure SCT15 cathode by over 5 times at 550 °C. This significant enhancement is likely attributable to the low CO2 adsorption and reactivity of the SDC protective layer, which are demonstrated through thermogravimetric analysis, energy-dispersive spectroscopy, and electrical conductivity study.

  3. 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.

  4. Li distribution characterization in Li-ion batteries positive electrodes containing LixNi0.8Co0.15Al0.05O2 secondary particles (0.75 ⩽ x ⩽ 1.0)

    NASA Astrophysics Data System (ADS)

    Mima, K.; Gonzalez-Arrabal, R.; Azuma, H.; Yamazaki, A.; Okuda, C.; Ukyo, Y.; Sawada, H.; Fujita, K.; Kato, Y.; Perlado, J. M.; Nakai, S.

    2012-11-01

    The elemental distribution of as-received (non-charged) and charged Li-ion battery positive electrodes containing LixNi0.8Co0.15Al0.05O2 (0.75 ⩽ x ⩽ 1.0) microparticles as active material is characterized by combining μ-PIXE and μ-PIGE techniques. PIGE measurements evidence that the Li distribution is inhomogeneous (existence of Li-rich and Li-depleted regions) in as-received electrodes corresponding with the distribution of secondary particles but it is homogeneous within the studied individual secondary micro-particles. The dependence of the Li distribution on electrode thickness and on charging conditions is characterized by measuring the Li distribution maps in specifically fabricated cross-sectional samples. These data show that decreasing the electrode thickness down to 35 μm and charging the batteries at slow rate give rise to more homogeneous Li depth profiles.

  5. Variations in Soil Microbial Biomass Carbon and Soil Dissolved Organic Carbon in the Re-Vegetation of Hilly Slopes with Purple Soil.

    PubMed

    Yang, Ning; Zou, Dongsheng; Yang, Manyuan; Lin, Zhonggui

    2016-01-01

    Crust restoration is increasingly being done but we lack quantitative information on soil improvements. The study aimed to elucidate the dynamics involving soil microbial biomass carbon and soil dissolved organic carbon in the re-vegetation chronosequences of a hillslope land with purple soil in Hengyang, Hunan Province. The soil can cause serious disasters with both soil erosion and seasonal drought, and also becomes a typical representative of ecological disaster area in South China. Using the space-for-time method, we selected six typical sampling plots, designated as follows: grassplot community, meadow thicket community, frutex community, frutex and arbor community, arbor community, and top-level vegetation community. These plots were established to analyze the changes in soil microbial biomass carbon, soil microbial quotien, dissolved organic carbon, dissolved organic carbon/soil organic carbon, and soil basal respiration in 0-10, 10-20, and 20-40 cm soil layers. The relationships of these parameters with soils physic-chemical properties were also determined. The ecological environment of the 6 plant communities is similar and typical; they denoted six different successive stages of restoration on hillslopes with purple soils in Hengyang, Hunan Province. The soil microbial biomass carbon and soil basal respiration contents decreased with increasing soil depth but increased with re-vegetation. By contrast, soil microbial quotient increased with increasing soil depth and re-vegetation. From 0-10 cm soil layer to 20-40 cm soil layer, the dissolved organic carbon content decreased in different re-vegetation stages. In the process of re-vegetation, the dissolved organic carbon content increased in the 0-10 and 10-20 cm soil layers, whereas the dissolved organic carbon content decreased after an initial increase in the 20-40 cm soil layers. Meanwhile, dissolved organic carbon/soil organic carbon increased with increasing soil depth but decreased with re

  6. Variations in Soil Microbial Biomass Carbon and Soil Dissolved Organic Carbon in the Re-Vegetation of Hilly Slopes with Purple Soil

    PubMed Central

    Yang, Ning; Zou, Dongsheng; Yang, Manyuan; Lin, Zhonggui

    2016-01-01

    Crust restoration is increasingly being done but we lack quantitative information on soil improvements. The study aimed to elucidate the dynamics involving soil microbial biomass carbon and soil dissolved organic carbon in the re-vegetation chronosequences of a hillslope land with purple soil in Hengyang, Hunan Province. The soil can cause serious disasters with both soil erosion and seasonal drought, and also becomes a typical representative of ecological disaster area in South China. Using the space-for-time method, we selected six typical sampling plots, designated as follows: grassplot community, meadow thicket community, frutex community, frutex and arbor community, arbor community, and top-level vegetation community. These plots were established to analyze the changes in soil microbial biomass carbon, soil microbial quotien, dissolved organic carbon, dissolved organic carbon/soil organic carbon, and soil basal respiration in 0–10, 10–20, and 20–40 cm soil layers. The relationships of these parameters with soils physic-chemical properties were also determined. The ecological environment of the 6 plant communities is similar and typical; they denoted six different successive stages of restoration on hillslopes with purple soils in Hengyang, Hunan Province. The soil microbial biomass carbon and soil basal respiration contents decreased with increasing soil depth but increased with re-vegetation. By contrast, soil microbial quotient increased with increasing soil depth and re-vegetation. From 0–10 cm soil layer to 20–40 cm soil layer, the dissolved organic carbon content decreased in different re-vegetation stages. In the process of re-vegetation, the dissolved organic carbon content increased in the 0–10 and 10–20 cm soil layers, whereas the dissolved organic carbon content decreased after an initial increase in the 20–40 cm soil layers. Meanwhile, dissolved organic carbon/soil organic carbon increased with increasing soil depth but decreased

  7. Soil Microbial Community Responses to Short-term Multiple Experimental Climate Change Drivers

    NASA Astrophysics Data System (ADS)

    Li, Guanlin; Lee, Jongyeol; Lee, Sohye; Roh, Yujin; Son, Yowhan

    2016-04-01

    It is agreed that soil microbial communities are responsible for the cycling of carbon and nutrients in ecosystems; however, the response of these microbial communities to climate change has not been clearly understood. In this study, we measured the direct and interactive effects of climate change drivers on soil bacterial and fungal communities (abundance and composition) in an open-field multifactor climate change experiment. The experimental treatment system was established with two-year-old Pinus densiflora seedlings at Korea University in April 2013, and consisted of six different treatments with three replicates: two levels of air temperature warming (control and +3° C) were crossed with three levels of precipitation manipulation (control, -30% and +30%). After 2.5 years of treatments, in August, 2015, soil samples were collected from the topsoil (0-15cm) of all plots (n=18). High-throughput sequencing technology was used to assess the abundance and composition of soil bacterial and fungal community. Analysis of variance for a blocked split-plot design was used to detect the effects of climate change drivers and their interaction on the abundance and composition of soil bacterial and fungal community. Our results showed that 1) only the significant effect of warming on fungal community abundance was observed (P <0.05); 2) on average, warming decreased both bacterial and fungal community abundance by 20.90% and 32.30%, 6.69% and 45.89%, 14.71% and 19.56% in control, decreased, and increased precipitation plots, respectively; 3) however, warming increased the relative bacterium/fungus ratio on average by 14.03%, 37.03% and 14.31% in control, decreased, and increased precipitation plots, respectively; 4) the phylogenetic distribution of bacterial and fungal groups and their relative abundance varied among treatments; 5) treatments altered the relative abundance of Ascomycota and Basidiomycota, where Ascomycota decreased with a concomitant increase in the

  8. Soil CO2 Dynamics in a Tree Island Soil of the Pantanal: The Role of Soil Water Potential

    PubMed Central

    Johnson, Mark S.; Couto, Eduardo Guimarães; Pinto Jr, Osvaldo B.; Milesi, Juliana; Santos Amorim, Ricardo S.; Messias, Indira A. M.; Biudes, Marcelo Sacardi

    2013-01-01

    The Pantanal is a biodiversity hotspot comprised of a mosaic of landforms that differ in vegetative assemblages and flooding dynamics. Tree islands provide refuge for terrestrial fauna during the flooding period and are particularly important to the regional ecosystem structure. Little soil CO2 research has been conducted in this region. We evaluated soil CO2 dynamics in relation to primary controlling environmental parameters (soil temperature and soil water). Soil respiration was computed using the gradient method using in situ infrared gas analyzers to directly measure CO2 concentration within the soil profile. Due to the cost of the sensors and associated equipment, this study was unreplicated. Rather, we focus on the temporal relationships between soil CO2 efflux and related environmental parameters. Soil CO2 efflux during the study averaged 3.53 µmol CO2 m−2 s−1, and was equivalent to an annual soil respiration of 1220 g C m−2 y−1. This efflux value, integrated over a year, is comparable to soil C stocks for 0–20 cm. Soil water potential was the measured parameter most strongly associated with soil CO2 concentrations, with high CO2 values observed only once soil water potential at the 10 cm depth approached zero. This relationship was exhibited across a spectrum of timescales and was found to be significant at a daily timescale across all seasons using conditional nonparametric spectral Granger causality analysis. Hydrology plays a significant role in controlling CO2 efflux from the tree island soil, with soil CO2 dynamics differing by wetting mechanism. During the wet-up period, direct precipitation infiltrates soil from above and results in pulses of CO2 efflux from soil. The annual flood arrives later, and saturates soil from below. While CO2 concentrations in soil grew very high under both wetting mechanisms, the change in soil CO2 efflux was only significant when soils were wet from above. PMID:23762259

  9. Soil CO₂ dynamics in a tree island soil of the Pantanal: the role of soil water potential.

    PubMed

    Johnson, Mark S; Couto, Eduardo Guimarães; Pinto, Osvaldo B; Milesi, Juliana; Santos Amorim, Ricardo S; Messias, Indira A M; Biudes, Marcelo Sacardi

    2013-01-01

    The Pantanal is a biodiversity hotspot comprised of a mosaic of landforms that differ in vegetative assemblages and flooding dynamics. Tree islands provide refuge for terrestrial fauna during the flooding period and are particularly important to the regional ecosystem structure. Little soil CO₂ research has been conducted in this region. We evaluated soil CO₂ dynamics in relation to primary controlling environmental parameters (soil temperature and soil water). Soil respiration was computed using the gradient method using in situ infrared gas analyzers to directly measure CO₂ concentration within the soil profile. Due to the cost of the sensors and associated equipment, this study was unreplicated. Rather, we focus on the temporal relationships between soil CO₂ efflux and related environmental parameters. Soil CO₂ efflux during the study averaged 3.53 µmol CO₂ m⁻² s⁻¹, and was equivalent to an annual soil respiration of 1220 g C m⁻² y⁻¹. This efflux value, integrated over a year, is comparable to soil C stocks for 0-20 cm. Soil water potential was the measured parameter most strongly associated with soil CO₂ concentrations, with high CO₂ values observed only once soil water potential at the 10 cm depth approached zero. This relationship was exhibited across a spectrum of timescales and was found to be significant at a daily timescale across all seasons using conditional nonparametric spectral Granger causality analysis. Hydrology plays a significant role in controlling CO₂ efflux from the tree island soil, with soil CO₂ dynamics differing by wetting mechanism. During the wet-up period, direct precipitation infiltrates soil from above and results in pulses of CO₂ efflux from soil. The annual flood arrives later, and saturates soil from below. While CO₂ concentrations in soil grew very high under both wetting mechanisms, the change in soil CO₂ efflux was only significant when soils were wet from above.

  10. Influence of urban land development and subsequent soil rehabilitation on soil aggregates, carbon, and hydraulic conductivity.

    PubMed

    Chen, Yujuan; Day, Susan D; Wick, Abbey F; McGuire, Kevin J

    2014-10-01

    Urban land use change is associated with decreased soil-mediated ecosystem services, including stormwater runoff mitigation and carbon (C) sequestration. To better understand soil structure formation over time and the effects of land use change on surface and subsurface hydrology, we quantified the effects of urban land development and subsequent soil rehabilitation on soil aggregate size distribution and aggregate-associated C and their links to soil hydraulic conductivity. Four treatments [typical practice (A horizon removed, subsoil compacted, A horizon partially replaced), enhanced topsoil (same as typical practice plus tillage), post-development rehabilitated soils (compost incorporation to 60-cm depth in subsoil; A horizon partially replaced plus tillage), and pre-development (undisturbed) soils] were applied to 24 plots in Virginia, USA. All plots were planted with five tree species. After five years, undisturbed surface soils had 26 to 48% higher levels of macroaggregation and 12 to 62% greater macroaggregate-associated C pools than those disturbed by urban land development regardless of whether they were stockpiled and replaced, or tilled. Little difference in aggregate size distribution was observed among treatments in subsurface soils, although rehabilitated soils had the greatest macroaggregate-associated C concentrations and pool sizes. Rehabilitated soils had 48 to 171% greater macroaggregate-associated C pool than the other three treatments. Surface hydraulic conductivity was not affected by soil treatment (ranging from 0.4 to 2.3 cm h(-1)). In deeper regions, post-development rehabilitated soils had about twice the saturated hydraulic conductivity (14.8 and 6.3 cm h(-1) at 10-25 cm and 25-40 cm, respectively) of undisturbed soils and approximately 6-11 times that of soils subjected to typical land development practices. Despite limited effects on soil aggregation, rehabilitation that includes deep compost incorporation and breaking of compacted

  11. [Effect of fertilization levels on soil microorganism amount and soil enzyme activities].

    PubMed

    Wang, Wei-Ling; Du, Jun-Bo; Xu, Fu-Li; Zhang, Xiao-Hu

    2013-11-01

    Field experiments were conducted in Shangluo pharmaceutical base in Shaanxi province to study the effect of nitrogen, phosphorus and potassium in different fertilization levels on Platycodon grandiflorum soil microorganism and activities of soil enzyme, using three-factor D-saturation optimal design with random block design. The results showed that N0P2K2, N2P2K0, N3P1K3 and N3P3K1 increased the amount of bacteria in 0-20 cm of soil compared with N0P0K0 by 144.34%, 39.25%, 37.17%, 53.58%, respectively. The amount of bacteria in 2040 cm of soil of N3P1K3 increased by 163.77%, N0P0K3 increased the amount of soil actinomycetes significantly by 192.11%, while other treatments had no significant effect. N2P0K2 and N3P1K3 increased the amounts of fungus significantly in 0-20 cm of soil compared with N0P0K0, increased by 35.27% and 92.21%, respectively. N3P0K0 increased the amounts of fungus significantly in 20-40 cm of soil by 165.35%, while other treatments had no significant effect. All treatments decrease soil catalase activity significantly in 0-20 cm of soil except for N2P0K2, and while N2P2K0 and NPK increased catalase activity significantly in 2040 cm of soil. Fertilization regime increased invertase activity significantly in 2040 cm of soil, and decreased phosphatase activity inordinately in 0-20 cm of soil, while increased phosphatase activity in 2040 cm of soil other than N1P3K3. N3P0K0, N0P0K3, N2P0K2, N2P2K0 and NPK increased soil urease activity significantly in 0-20 cm of soil compared with N0P0K0 by 18.22%, 14.87%,17.84%, 27.88%, 24.54%, respectively. Fertilization regime increased soil urease activity significantly in 2040 cm of soil other than N0P2K2.

  12. 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.

  13. Soil organic carbon covariance with soil water content; a geostatistical analysis in cropland fields

    NASA Astrophysics Data System (ADS)

    Manns, H. R.; Berg, A. A.; von Bertoldi, P.

    2013-12-01

    Soil texture has traditionally represented the rate of soil water drainage influencing soil water content (WC) in the soil characteristic curves, hydrological models and remote sensing field studies. Although soil organic carbon (OC) has been shown to significantly increase the water holding capacity of soil in individual field studies, evidence is required to consider soil OC as a significant factor in soil WC variability at the scale of a remote sensing footprint (25 km2). The relationship of soil OC to soil WC was evaluated over 50 fields during the Soil Moisture Active Passive (SMAP) soil WC field sampling campaign over southern Manitoba, Canada. On each field, soil WC was measured at 16 sample points, at 100 m spacing to 5 cm depth with Stevens hydra probe sensors on 16 sampling dates from June 7 to July 19, 2012. Soil cores were also taken at sampling sites on each field, each sampling day, to determine gravimetric moisture, bulk density and particle size distribution. On 4 of the sampling dates, soil OC was also determined by loss on ignition on the dried soil samples from all fields. Semivariograms were created from the field mean soil OC and field mean surface soil WC sampled at midrow, over all cropland fields and averaged over all sampling dates. The semivariogram models explained a distinct relationship of both soil OC and WC within the soil over a range of 5 km with a Gaussian curve. The variance in soil that soil OC and WC have in common was a similar Gaussian curve in the cross variogram. Following spatial interpolation with Kriging, the spatial maps of soil OC and WC were also very similar with high covariance over the majority of the sampling area. The close correlation between soil OC and WC suggests they are structurally related in the soil. Soil carbon could thus assist in improving downscaling methods for remotely sensed soil WC and act as a surrogate for interpolation of soil WC.

  14. Soil organic carbon distribution in roadside soils of Singapore.

    PubMed

    Ghosh, Subhadip; Scharenbroch, Bryant C; Ow, Lai Fern

    2016-12-01

    Soil is the largest pool of organic carbon in terrestrial systems and plays a key role in carbon cycle. Global population living in urban areas are increasing substantially; however, the effects of urbanization on soil carbon storage and distribution are largely unknown. Here, we characterized the soil organic carbon (SOC) in roadside soils across the city-state of Singapore. We tested three hypotheses that SOC contents (concentration and density) in Singapore would be positively related to aboveground tree biomass, soil microbial biomass and land-use patterns. Overall mean SOC concentrations and densities (0-100 cm) of Singapore's roadside soils were 29 g kg(-1) (4-106 g kg(-1)) and 11 kg m(-2) (1.1-42.5 kg m(-2)) with median values of 26 g kg(-1) and 10 kg m(-2), respectively. There was significantly higher concentration of organic carbon (10.3 g kg(-1)) in the top 0-30 cm soil depth compared to the deeper (30-50 cm, and 50-100 cm) soil depths. Singapore's roadside soils represent 4% of Singapore's land, but store 2.9 million Mg C (estimated range of 0.3-11 million Mg C). This amount of SOC is equivalent to 25% of annual anthropogenic C emissions in Singapore. Soil organic C contents in Singapore's soils were not related to aboveground vegetation or soil microbial biomass, whereas land-use patterns to best explain variance in SOC in Singapore's roadside soils. We found SOC in Singapore's roadside soils to be inversely related to urbanization. We conclude that high SOC in Singapore roadside soils are probably due to management, such as specifications of high quality top-soil, high use of irrigation and fertilization and also due to an optimal climate promoting rapid growth and biological activity.

  15. 'Natural background' soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence

    USGS Publications Warehouse

    Doerr, S.H.; Woods, S.W.; Martin, D.A.; Casimiro, M.

    2009-01-01

    therefore incorrect. It follows that, where pre-fire water repellency levels are not known or highly variable, post-fire soil water repellency conditions are an unreliable indicator in classifying soil burn severity. The terrain and soil variables examined showed, overall, no convincing relationship with the repellency levels observed (R2 < 0.15) except that repellency was limited in soils (i) developed over meta-sedimentary lithology and (ii) with clay contents >4%. This suggests that water repellency levels cannot be predicted with confidence from common terrain or soil variables. ?? 2009 Elsevier B.V.

  16. The GLOBE Soil Moisture Campaign's Light Bulb Oven

    NASA Astrophysics Data System (ADS)

    Whitaker, M. P.; Tietema, D.; Ferre, T. P.; Nijssen, B.; Washburne, J.

    2003-12-01

    The GLOBE Soil Moisture Campaign (SMC) (www.hwr.arizona.edu/globe/sci/SM/SMC) has developed a light bulb oven to provide a low budget, low-technology method for drying soil samples. Three different soils were used to compare the ability of the light bulb oven to dry soils against a standard laboratory convection oven. The soils were: 1) a very fine sandy loam (the "Gila" soil); 2) a silty clay (the "Pima" soil); and 3) a sandy soil (the "Sonoran" soil). A large batch of each soil was wetted uniformly in the laboratory. Twelve samples of each soil were placed in the light bulb oven and twelve samples were placed in the standard oven. The average gravimetric soil moisture of the Gila soil was 0.214 g/cm3 for both ovens; the average Pima soil moisture was 0.332 g/cm3 and 0.331 g/cm3 for the traditional and light bulb ovens, respectively; and the Sonoran soil moisture was 0.077 g/cm3 for both ovens. These results demonstrate that the low technology light-bulb oven was able to dry the soil samples as well as a standard laboratory oven, offering the ability to make gravimetric water content measurements when a relatively expensive drying oven is not available.

  17. Spatiotemporal characteristics of soil temperature memory in China from observation

    NASA Astrophysics Data System (ADS)

    Yang, Kai; Zhang, Jingyong

    2016-11-01

    Similar to soil moisture, soil temperature has a memory of atmospheric anomalies. However, soil temperature memory over China is still largely unclear, especially in observation. In this study, we investigate the spatiotemporal characteristics of soil temperature memory over China using subsurface (10-80 cm) and deep (160-320 cm) soil temperature data for 626 stations during the period of 1981 to 2005. The red noise method is adopted to estimate soil temperature memory. Results show that the soil temperature memory differs spatially and varies with soil depth and season. Influenced by climate regimes, soil temperature memory at all six layers (with depths of 10, 20, 40, 80, 160, and 320 cm) shows a similar spatial pattern dominated by a northwest to southeast gradient, with relatively high values over arid and semiarid areas of northwestern part of China and relatively low values over humid and semihumid areas of southeastern part of China. During all four seasons, memory lengths increase with soil depth. The average memory of subsurface soil over China can last several months, and for soil at 320 cm, it can be 1 year or more. We also find that seasonal and regional differences of soil temperature memory are stronger in deep soil layers than those in subsurface soil layers. Our findings suggest that soil temperature memory can offer potential for improving seasonal climate prediction over northwestern China. In the meanwhile, the limitations of the methods used in this study should be recognized.

  18. 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.

  19. 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.

  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. High-resolution comparative modeling with RosettaCM.

    PubMed

    Song, Yifan; DiMaio, Frank; Wang, Ray Yu-Ruei; Kim, David; Miles, Chris; Brunette, Tj; Thompson, James; Baker, David

    2013-10-08

    We describe an improved method for comparative modeling, RosettaCM, which optimizes a physically realistic all-atom energy function over the conformational space defined by homologous structures. Given a set of sequence alignments, RosettaCM assembles topologies by recombining aligned segments in Cartesian space and building unaligned regions de novo in torsion space. The junctions between segments are regularized using a loop closure method combining fragment superposition with gradient-based minimization. The energies of the resulting models are optimized by all-atom refinement, and the most representative low-energy model is selected. The CASP10 experiment suggests that RosettaCM yields models with more accurate side-chain and backbone conformations than other methods when the sequence identity to the templates is greater than ∼15%.

  2. 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.

  3. 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. This paper presents the cycle life test results and also 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.

  4. 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.

  5. 21 cm radiation: A new probe of fundamental physics

    NASA Astrophysics Data System (ADS)

    Khatri, Rishi; Wandelt, Benjamin D.

    2010-11-01

    New low frequency radio telescopes currently being built open up the possibility of observing the 21 cm radiation from redshifts 200 > z > 30, also known as the dark ages, see Furlanetto, Oh, & Briggs(2006) for a review. At these high redshifts, Cosmic Microwave Background (CMB) radiation is absorbed by neutral hydrogen at its 21 cm hyperfine transition. This redshifted 21 cm signal thus carries information about the state of the early Universe and can be used to test fundamental physics. The 21 cm radiation probes a volume of the early Universe on kpc scales in contrast with CMB which probes a surface (of some finite thickness) on Mpc scales. Thus there is many orders of more information available, in principle, from the 21 cm observations of dark ages. We have studied the constraints these observations can put on the variation of fundamental constants (Khatri & Wandelt(2007)). Since the 21 cm signal depends on atomic physics it is very sensitive to the variations in the fine structure constant and can place constraints comparable to or better than the other astrophysical experiments (Δα/α= < 10-5) as shown in Figure 1. Making such observations will require radio telescopes of collecting area 10 - 106 km2 compared to ~ 1 km2 of current telescopes, for example LOFAR. We should also expect similar sensitivity to the electron to proton mass ratio. One of the challenges in observing this 21 cm cosmological signal is the presence of the synchrotron foregrounds which is many orders of magnitude larger than the cosmological signal but the two can be separated because of their different statistical nature (Zaldarriaga, Furlanetto, & Hernquist(2004)). Terrestrial EM interference from radio/TV etc. and Earth's ionosphere poses problems for telescopes on ground which may be solved by going to the Moon and there are proposals for doing so, one of which is the Dark Ages Lunar Interferometer (DALI). In conclusion 21 cm cosmology promises a large wealth of data and provides

  6. WSRC Am/Cm Stabilization Program - Cylindrical Induction Melter Studies

    SciTech Connect

    Henderson, W.A.

    1999-02-17

    1.1.1 Kilogram quantities of Americium and Curium isotopes (Am/Cm) have been produced at the U.S. Department of Energy (DOE), Savannah River Site (SRS), Aiken, South Carolina. These highly radioactive isotopes have both government and commercial value and are currently stored as a nitric acid solution at the Savannah River Site. The material represents the largest source term in the F canyon at SRS. It is proposed that the Am/Cm material be vitrified to stabilize the material for long term, recoverable storage. This paper reviews the progress made during the process development phase of this program using the Cylindrical Induction Melter.

  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. Increased capabilities of the 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Hawkins, C. E.

    1979-01-01

    Some space flight missions require advanced ion thrusters which operate at conditions much different than those for which the baseline 30-cm Hg thruster was developed. Results of initial tests of a 30-cm Hg thruster with two and three grid ion accelerating systems, operated at higher values of both thrust and power and over a greater range of specific impulse than the baseline conditions are presented. Thruster lifetime at increased input power was evaluated both by extended tests and real time spectroscopic measurements.

  9. Inert gas test of two 12-cm magnetostatic thrusters

    NASA Technical Reports Server (NTRS)

    Ramsey, W. D.

    1982-01-01

    Comparative performance tests were conducted with 12 cm line and ring magnetic cusp thrusters. Shell anode and magnetoelectrostatic containment boundary anode configurations were evaluated with each magnet array. The best performance was achieved with the 12-cm ring cusp-shell anode configuration. Argon operation of this configuration produced 65-81 percent mass utilization efficiency at 170-208 watts/single-charged-equivalent (SCE) ampere beam. Xenon test results showed 75-95 percent utilization at 162-188 watts/SCE ampere beam.

  10. Spatial variations of heavy metals in the soils of vegetable-growing land along urban-rural gradient of Nanjing, China.

    PubMed

    Fang, Shi-Bo; Hu, Hao; Sun, Wan-Chun; Pan, Jian-Jun

    2011-06-01

    China has experienced rapid urbanization in recent years. The acceleration of urbanization has created wealth and opportunity as well as intensified ecological and environmental problems, especially soil pollution. Our study concentrated on the variation of heavy metal content due to urbanization in the vegetable-growing soil. Laws and other causes of the spatial-temporal variation in heavy metal content of vegetable-growing soils were analyzed for the period of urbanization in Nanjing (the capital of Jiangsu province in China). The levels of Cu, Zn, Pb, Cd and Hg in samples of vegetable-growing soil were detected. The transverse, vertical spatio-temporal variation of heavy metals in soil was analyzed on the base of field investigations and laboratory analysis. The results show that: (1) in soil used for vegetable production, the levels of heavy metals decreased gradually from urban to rural areas; the levels of the main heavy metals in urban areas are significantly higher than suburban and rural areas; (2) the means of the levels of heavy metals, calculated by subtracting the sublayer (15-30 cm) from the toplayer (0-15 cm), are all above zero and large in absolute value in urban areas, but in suburban and rural areas, the means are all above or below zero and small in absolute value. The causes of spatial and temporal variation were analyzed as follows: one cause was associated with mellowness of the soil and the length of time the soil had been used for vegetable production; the other cause was associated with population density and industrial intensity decreasing along the urban to rural gradient (i.e., urbanization levels can explain the distribution of heavy metals in soil to some extent). Land uses should be planned on the basis of heavy metal pollution in soil, especially in urban and suburban regions. Heavily polluted soils have to be expected from food production. Further investigation should be done to determine whether and what kind of agricultural

  11. Temperature sensitivity (Q10), and dynamics of soil organic matter (SOM) decomposition in permafrost soils with different carbon quality and under experimental warming. R. Bracho1, E.A.G Schuur1, E. Pegoraro1, K.G. Crummer1, S. Natali2, J. Zhou, Y Luo3, J. L. Wu3, M. Tiedje4, K. Konstantinidis5 1Department of Biology, University of Florida, Gainesville, FL. 2Woods Hole Research Center, Falmouth, MA. 3Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK, 4Center for Microbial Ecology, Michigan State University, East Lansing, MI; 5Center for Bioinformatics and Computational Genomics and School of Biology, Georgia Institute of Technology, Atlanta, GA

    NASA Astrophysics Data System (ADS)

    Bracho, R. G.; Schuur, E. A.; Pegoraro, E.; Crummer, K. G.; Natali, S.; Zhou, J.; Wu, L.; Luo, Y.; Tiedje, J. M.; Konstantinidis, K.

    2013-12-01

    Permafrost soils contain approximately1700 Pg of carbon (C), twice the amount of C in the atmosphere. Temperatures in higher latitudes are increasing, inducing permafrost thaw and subsequent microbial decomposition of previously frozen C. This process is one of the most likely positive feedbacks to climate change. Understanding the temperature sensitivity (Q10) and dynamics of SOM decomposition under warming is essential to predict the future state of the earth - climate system. Alaskan tundra soils were exposed to two winter warming (WW) seasons in the field, which warmed the soils by 4°C to 40 cm depth. Soils were obtained from three depths (0 - 15, 15 - 25 and 45 - 55 cm) and differed in initial amounts of labile and recalcitrant C. Soils were incubated in the lab under aerobic conditions, at 15 and 25°C over 365 days. Q10 was estimated at 14, 100 & 280 days of incubation (DOI); C fluxes were measured periodically and dynamics of SOM decomposition (C pool sizes and decay rates) were estimated by fitting a two pool C model to cumulative respired C (Ccum, mgC/ginitialC). After two WW seasons, initial C content tended to decrease through the soil profile and C:N ratio was significantly decreased in the top 15 cm. After one year of incubation, Ccum was twice as high at 25°C as at 15°C and significantly decreased with depth. No significant WW field treatment was detected, although Ccum tended to be lower in warmed soils. Labile C accounted for up to 5% of initial soil C content in the top 15 cm and decreased with depth. Soils exposed to WW had smaller labile C pools, and higher labile C decay rates in the top 25 cm. Q10 significantly decreased with time and depth as labile pool decreased, especially for WW. This decrease with time indicates a lower temperature sensitivity of the most recalcitrant C pool. The deepest WW soil layer, where warming was more pronounced, had significantly lower Q10 compared to control soils at the same depth. After two seasons, the

  12. Passive microwave soil moisture research

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Oneill, P. E.; Wang, J. R.

    1985-01-01

    The AgRISTARS Soil Moisture Project has made significant progress in the quantification of microwave sensor capabilities for soil moisture remote sensing. The 21-cm wavelength has been verified to be the best single channel for radiometric observations of soil moisture. It has also been found that other remote sensing approaches used in conjunction with L-band passive data are more successful than multiple wavelength microwave radiometry in this application. AgRISTARS studies have also improved current understanding of noise factors affecting the interpretability of microwave emission data. The absorption of soil emission by vegetation has been quantified, although this effect is less important than absorption effects for microwave radiometry.

  13. 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

  14. Vertical distribution of soil removed by four species of burrowing rodents in disturbed and undisturbed soils

    SciTech Connect

    Reynolds, T.D.; Laundre, J.W.

    1988-04-01

    Burrow volumes were determined in disturbed and undisturbed soils for four species of rodents in southeastern Idaho. Comparisons were made between soil types for the average volume and the proportion of the total volume of soil excavated from 10-cm increments for each species, and the relative number of burrows and proportion of total soil removed from beneath the minimum thickness of soil covers over buried low-level radioactive wastes. Burrows of montane voles (Microtus montanus) and deer mice (Peromyscus maniculatus) rarely extended below 50 cm and neither volumes nor depths were influenced by soil disturbance. Townsend's ground squirrels (Spermophilus townsendii) had the deepest and most voluminous burrows that, along with Ord's kangaroo rat (Dipodomys ordii) burrows, were more prevalent beneath 50 cm in disturbed soils.

  15. Soil and Surface Runoff Phosphorus Relationships for Five Typical USA Midwest Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excessively high soil P can increase P loss with surface runoff. This study used indoor rainfall simulations to characterize soil and runoff P relationships for five Midwest soils (Argiudoll, Calciaquaoll, Hapludalf, and two Hapludolls). Topsoil (15-cm depth, 241–289 g clay kg–1 and pH 6.0–8.0) was ...

  16. 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.

  17. Soil temperature prediction from air temperature for alluvial soils in lower Indo-Gangetic plain

    NASA Astrophysics Data System (ADS)

    Barman, D.; Kundu, D. K.; Pal, Soumen; Pal, Susanto; Chakraborty, A. K.; Jha, A. K.; Mazumdar, S. P.; Saha, R.; Bhattacharyya, P.

    2017-01-01

    Soil temperature is an important factor in biogeochemical processes. On-site monitoring of soil temperature is limited in spatiotemporal scale as compared to air temperature data inventories due to various management difficulties. Therefore, empirical models were developed by taking 30-year long-term (1985-2014) air and soil temperature data for prediction of soil temperatures at three depths (5, 15, 30 cm) in morning (0636 Indian standard time) and afternoon (1336 Indian standard time) for alluvial soils in lower Indo-Gangetic plain. At 5 cm depth, power and exponential regression models were best fitted for daily data in morning and afternoon, respectively, but it was reverse at 15 cm. However, at 30 cm, exponential models were best fitted for both the times. Regression analysis revealed that in morning for all three depths and in afternoon for 30 cm depth, soil temperatures (daily, weekly, and monthly) could be predicted more efficiently with the help of corresponding mean air temperature than that of maximum and minimum. However, in afternoon, prediction of soil temperature at 5 and 15 cm depths were more precised for all the time intervals when maximum air temperature was used, except for weekly soil temperature at 15 cm, where the use of mean air temperature gave better prediction.

  18. Sayama CM2 Chondrite: Fresh but Heavily Altered

    NASA Technical Reports Server (NTRS)

    Takaoka, N.; Nakamura, T.; Noguchi, T.; Tonui, E.; Gounelle, M.; Zolensky, M. E.; Ebisawa, N.; Osawa, T.; Okazaki, R.; Nagao, K.; Yoneda, S.

    2001-01-01

    Noble gas composition and mineralogy of Sayama meteorite, that fell in Japan and recently identified as a CM2 chondrite, revealed many unique features, indicating that it experienced extensive aqueous alteration under highly oxidized condition compared with typical CMs. Additional information is contained in the original extended abstract.

  19. 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.

  20. Organic Matter Inclusions in CM2 Chondrite Murchison

    NASA Astrophysics Data System (ADS)

    Peeters, Z.; Liebig, B.; Lee, T.

    2015-07-01

    Large (~10 μm) inclusions of pure organic carbon exist in carbonaceous chondrites. We extracted organic inclusions from Murchison, a CM2, and analyzed the sections using XANES, TEM, and nanoSIMS. The results are compared to previous results of CRs.

  1. 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.

  2. 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.

  3. 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…

  4. Case study: developing product lines using ICD-9-CM codes.

    PubMed

    Benz, P D; Burnham, J

    1985-12-01

    In this marketing case study, Thomas Jefferson University Hospital used a product line approach to maximize the use of its resources. The method used, based on ICD-9-CM codes, fulfilled the demands of increased efficiency by encouraging customer-oriented thinking, enhancing communication with physicians and patients, and helping the institution to compete more effectively.

  5. Oxygen isotope constraints on the alteration temperatures of CM chondrites

    NASA Astrophysics Data System (ADS)

    Verdier-Paoletti, Maximilien J.; Marrocchi, Yves; Avice, Guillaume; Roskosz, Mathieu; Gurenko, Andrey; Gounelle, Matthieu

    2017-01-01

    We report a systematic oxygen isotopic survey of Ca-carbonates in nine different CM chondrites characterized by different degrees of alteration, from the least altered known to date (Paris, 2.7-2.8) to the most altered (ALH 88045, CM1). Our data define a continuous trend that crosses the Terrestrial Fractionation Line (TFL), with a general relationship that is indistinguishable within errors from the trend defined by both matrix phyllosilicates and bulk O-isotopic compositions of CM chondrites. This bulk-matrix-carbonate (BMC) trend does not correspond to a mass-dependent fractionation (i.e., slope 0.52) as it would be expected during fluid circulation along a temperature gradient. It is instead a direct proxy of the degree of O-isotopic equilibration between 17,18O-rich fluids and 16O-rich anhydrous minerals. Our O-isotopic survey revealed that, for a given CM, no carbonate is in O-isotopic equilibrium with its respective surrounding matrix. This precludes direct calculation of the temperature of carbonate precipitation. However, the O-isotopic compositions of alteration water in different CMs (inferred from isotopic mass-balance calculation and direct measurements) define another trend (CMW for CM Water), parallel to BMC but with a different intercept. The distance between the BMC and CMW trends is directly related to the temperature of CM alteration and corresponds to average carbonates and serpentine formation temperatures of 110 °C and 75 °C, respectively. However, carbonate O-isotopic variations around the BMC trend indicate that they formed at various temperatures ranging between 50 and 300 °C, with 50% of the carbonates studied here showing precipitation temperature higher than 100 °C. The average Δ17O and the average carbonate precipitation temperature per chondrite are correlated, revealing that all CMs underwent similar maximum temperature peaks, but that altered CMs experienced protracted carbonate precipitation event(s) at lower temperatures than

  6. The amino acid and hydrocarbon contents of the Paris meteorite: Insights into the most primitive CM chondrite

    NASA Astrophysics Data System (ADS)

    Martins, Zita; Modica, Paola; Zanda, Brigitte; D'Hendecourt, Louis Le Sergeant

    2015-05-01

    The Paris meteorite is one of the most primitive carbonaceous chondrites. It is reported to be the least aqueously altered CM chondrite, and to have experienced only weak thermal metamorphism. We have analyzed for the first time the amino acid and hydrocarbon contents of this pristine meteorite by gas chromatography-mass spectrometry (GC-MS). When plotting the relative amino acids abundances of several CM chondrites according to the increasing hydrothermal scale (petrologic subtypes), from the CM2.7/2.8 Paris to the CM2.0 MET 01070, Paris has the lowest relative abundance of β-alanine/glycine (0.15), which fits with the relative abundances of β-alanine/glycine increasing with increasing aqueous alteration for CM chondrites. These results confirm the influence of aqueous alteration on the amino acid abundances and distribution. The amino acid analysis shows 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%). The identified hydrocarbons show that Paris has n-alkanes ranging from C16 to C25 and 3- to 5-ring nonalkylated polycyclic aromatic hydrocarbons (PAHs). The lack of alkylated PAHs in Paris seems to be also related to this low degree of aqueous alteration on its parent body. The extraterrestrial hydrocarbon content, suggested by the absence of any biomarker, may well have a presolar origin. The chemistry of the Paris meteorite may thus be closely related to the early stages of the solar nebula with a contribution from interstellar (molecular cloud) precursors.

  7. 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.

  8. Inorganic Nutrients Increase Humification Efficiency and C-Sequestration in an Annually Cropped Soil

    PubMed Central

    Richardson, Alan E.; Wade, Len J.; Conyers, Mark; Kirkegaard, John A.

    2016-01-01

    Removing carbon dioxide (CO2) from the atmosphere and storing the carbon (C) in resistant soil organic matter (SOM) is a global priority to restore soil fertility and help mitigate climate change. Although it is widely assumed that retaining rather than removing or burning crop residues will increase SOM levels, many studies have failed to demonstrate this. We hypothesised that the microbial nature of resistant SOM provides a predictable nutrient stoichiometry (C:nitrogen, C:phosphorus and C:sulphur–C:N:P:S) to target using supplementary nutrients when incorporating C-rich crop residues into soil. An improvement in the humification efficiency of the soil microbiome as a whole, and thereby C-sequestration, was predicted. In a field study over 5 years, soil organic-C (SOC) stocks to 1.6 m soil depth were increased by 5.5 t C ha-1 where supplementary nutrients were applied with incorporated crop residues, but were reduced by 3.2 t C ha-1 without nutrient addition, with 2.9 t C ha-1 being lost from the 0–10 cm layer. A net difference of 8.7 t C ha-1 was thus achieved in a cropping soil over a 5 year period, despite the same level of C addition. Despite shallow incorporation (0.15 m), more than 50% of the SOC increase occurred below 0.3 m, and as predicted by the stoichiometry, increases in resistant SOC were accompanied by increases in soil NPS at all depths. Interestingly the C:N, C:P and C:S ratios decreased significantly with depth possibly as a consequence of differences in fungi to bacteria ratio. Our results demonstrate that irrespective of the C-input, it is essential to balance the nutrient stoichiometry of added C to better match that of resistant SOM to increase SOC sequestration. This has implications for global practices and policies aimed at increasing SOC sequestration and specifically highlight the need to consider the hidden cost and availability of associated nutrients in building soil-C. PMID:27144282

  9. Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

    NASA Astrophysics Data System (ADS)

    Juszak, Inge; Eugster, Werner; Heijmans, Monique M. P. D.; Schaepman-Strub, Gabriela

    2016-07-01

    Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17 ± 0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and

  10. soil organic matter pools and quality are sensitive to global climate change in tropical forests from India

    NASA Astrophysics Data System (ADS)

    Mani, Shanmugam; Merino, Agustín; García-Oliva, Felipe; Riotte, Jean; Sukumar, Raman

    2016-04-01

    Soil organic carbon (SOC) storage and quality are some of the most important factors determining ecological process in tropical forests, which are especially sensitive to global climate change (GCC). In India, the GCC scenarios expect increasing of drought period and wildfire, which may affect the SOC, and therefore the capacity of forest for C sequestration. The aim of the study was to evaluate the amount of soil C and its quality in the mineral soil across precipitation gradient with different factors (vegetation, pH, soil texture and bedrock composition) for generate SOC predictions under GCC. Six soil samples were collected (top 10 cm depth) from 19 1-ha permanent plots in the Mudumalai Wildlife Sanctuary of southern India, which are characterised by four types of forest vegetation (i.e. dry thorn, dry deciduous, moist deciduous and semi-evergreen forest) distributed along to rainfall gradient. The driest sites are dominated by sandy soils, while the soil clay proportion increased in the wet sites. Total organic C (Leco CN analyser), and the SOM quality was assessed by Differential Scanning Calorimetry (DSC) and Solid-state 13CCP-MAS NMR analyses. Soil organic C was positively correlated with precipitation (R2 = 0.502, p<0.01) and with soil clay content (R2 =0.15, p<0.05), and negatively with soil sand content (R2=0.308, p<0.001) and with pH (R2=0.529, p<0.01); while the C/N was only found positive correlation with clay (R2= 0.350, p<0.01). The driest sites (dry thorn forest) has the lowest proportion of thermal combustion of recalcitrant organic matter (Q2,375-475 °C) than the other sites (p<0.05) and this SOC fraction correlated positively with rainfall (R2=0.27, p=0.01). The Q2 model with best fit included rainfall, pH, sand, clay, C and C/N (R2=0.52, p=0.01). Principal component analysis explains 77% of total variance. The sites on the fist component are distributed along the rainfall gradient. These results suggest that the 50% of variance was explained

  11. Short term recovery of soil physical, chemical, micro- and mesobiological functions in a new vineyard under organic farming

    NASA Astrophysics Data System (ADS)

    Costantini, E. A. C.; Agnelli, A. E.; Fabiani, A.; Gagnarli, E.; Mocali, S.; Priori, S.; Simoni, S.; Valboa, G.

    2014-12-01

    Deep earthwork activities carried out before vineyard plantation can severely upset soil profile properties. As a result, soil features in the root environment are often much more similar to those of the underlying substratum than those of the original profile. The time needed to recover the original soil functions is ecologically relevant and may strongly affect vine phenology and grape yield, particularly under organic viticulture. The general aim of this work was to investigate soil resilience after vineyard pre-planting earthworks. In particular, an old and a new vineyard, established on the same soil type, were compared over a five year period for soil chemical, physical, micro and mesobiological properties. The investigated vineyards (Vitis vinifera L., cv. Sangiovese) were located in the Chianti Classico district (Central Italy), on stony and calcareous soils and were not irrigated. The older vineyard was planted in 2000, after slope reshaping by bulldozing and back hoe ploughing down to about 0.8-1.0 m. The new vineyard was planted in 2011, after equivalent earthwork practices carried out in the summer of 2009. Both vineyards were organically managed and fertilized only with compost every autumn (1000 kg ha-1 per year). The new vineyard was cultivated by periodic tillage, while the old vineyard was managed with alternating grass-covered and tilled inter-rows. Soil samples were collected at 0-15 cm depth from the same plots of the new and old vineyards, during the springtime from 2010 to 2014. The old vineyard was sampled in both the tilled and the grass-covered swaths. According to the results from physical and chemical analyses, the new vineyard, during the whole 2010-2014 period, showed lower TOC, N, C/N and EC values, along with higher silt and total CaCO3 contents than the old vineyard, suggesting still evolving equilibrium conditions. The microarthropod analysis showed significantly different abundances and communities' structures, in relation to both

  12. 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

  13. LETTER TO THE EDITOR: The interrelationship of Cu effective charge and superconductivity in the T´-type Gd1.85- xPrxCe0.15CuOy system

    NASA Astrophysics Data System (ADS)

    Gupta, Sanjay; Prakash, Om; Padalia, B. D.; Gopalakrishnan, I. K.; Yakhmi, J. V.; Patnaik, A. K.

    2000-01-01

    The lattice oxygen content (y ) is measured and the effective charge (n ) on Cu is calculated for the T´-type Gd1.85-x Prx Ce0.15 CuOy 0.0icons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> xicons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> 1.85 compounds. It is found that the superconductive response (Tc onset) of the samples is related to n . Whenever nicons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> 1.87 (+/-0.01), the compounds are superconducting. The optimum Tc is seen for n ~1.79 which is in good agreement with the values of n (1.77icons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> nicons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> 1.84) calculated from the reported y in different optimum Tc T´-cuprates. This brings out a universality in the interrelationship between n and Tc .

  14. Magnetocaloric effect and the influence of pressure on magnetic properties of La-excess pseudo-binary alloys La1+δ(Fe0.85Si0.15)13

    NASA Astrophysics Data System (ADS)

    Vuong, Van Hiep; Do Thi, Kim Anh; Thuan Nguyen, Khac; Le, Van Hong; Nhat Hoang, Nam

    2016-10-01

    The La-excess alloys La1+δ(Fe0.85Si0.15)13 (δ = 0.06 and 0.09) exhibit large magnetocaloric effect which has been attributed to the occurrence of itinerant-electron metamagnetic transition near the Curie temperature TC. The maximum entropy change -ΔSm was shown to be from 4.5 to 11.5 J/kg K for the applied field variation ΔH from 20 to 70 kOe, respectively. The estimated relative cooling power for ΔH = 70 kOe was 418 J/kg. The alloys show a typical NaZn13-type cubic structure, featuring a doping-induced magnetovolume effect with the increase in TC. Under the applied pressure up to 2 GPa, the TC as deduced from resistance measurements decreased linearly, ΔTC = 113 (for δ = 0.06) and 111 K (for δ = 0.09), together with a corresponding decrease of resistivity, Δρ = 6.1 μΩ m at room temperature for both samples. At a low pressure, the effect of spontaneous magnetostriction on TC caused by applying the pressure appeared to have a similar magnitude to that of the negative magnetovolume effect caused by La-excess doping. In comparison with other stoichiometric La(Fe1-xSix)13 compounds, the pressure in our case was shown to have a smaller influence on TC.

  15. Energy dependence of the electron-boson coupling strength in the electron-doped cuprate superconductor Pr1.85Ce0.15CuO4 -δ

    NASA Astrophysics Data System (ADS)

    Beck, M.; Klammer, M.; Rousseau, I.; Obergfell, M.; Leiderer, P.; Helm, M.; Kabanov, V. V.; Diamant, I.; Rabinowicz, A.; Dagan, Y.; Demsar, J.

    2017-02-01

    The quest for a pairing boson in cuprate high-temperature superconductors is one of the outstanding tasks of solid-state physics. Numerous time-resolved studies of pair breaking, related to pairing by time-reversal symmetry, have been performed using femtosecond optical pulses. By considering energy relaxation pathways between charge, spin, and lattice degrees of freedom, evidence for both phonon and antiferromagnetic fluctuation-mediated pairing has been obtained. Here we present a study of the superconducting-state depletion process in an electron-doped cuprate Pr1.85Ce0.15CuO4 -δ , where the superconducting gap is smaller than the energy of relevant bosonic excitations. When pumping with above-gap terahertz pulses, we find that the absorbed energy density required to deplete superconductivity, Adep, matches the thermodynamic condensation energy. On the contrary, by near-infrared pumping, Adep is an order of magnitude higher, as in the case of hole-doped, large-gap cuprates. These results imply that only a small subset of bosons, which are generated during the relaxation of optically excited carriers, contributes to pairing. This observation implies that, contrary to the common assumptions, electron-boson coupling in cuprates is strongly energy dependent.

  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. 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.

  18. 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.

  19. Development and understanding of La0.85Sr0.15Cr1-xNixO3-δ anodes for La5.6WO11.4-δ-based Proton Conducting Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Solís, Cecilia; Navarrete, Laura; Balaguer, María; Serra, José M.

    2014-07-01

    Porous electrodes based on the system La0.85Sr0.15Cr1-xNixO3-δ (x = 0.1 and 0.2) have been investigated as anodes for proton conducting solid oxide fuel cells based on the La5.6WO11.4-δ (LWO) electrolyte material. The microstructure of the anodes was optimized by varying both the starting powder morphology and the final anode sintering temperature. Two different electrode thicknesses were studied, i.e. 15 and 30 μm. The importance of the catalytic role of Ni was also studied by using different concentrations of Ni (10% and 20%) in the chromite and by tuning the Ni particle sizes through the control of the reduction temperature. Additionally, a ceramic-ceramic (cer-cer) composite electrode comprising a physical mixture of the optimized chromite and LWO phase was also considered. Finally, a kinetics study and modeling based on Langmuir-Hinshelwood mechanism was carried out in order to quantitatively describe the rate of dissociative adsorption of H2 on the Ni particles spread on the chromite surface.

  20. 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.

  1. The enhancing performance of (Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.90}Zr{sub 0.10})O{sub 3} ceramics by tuning anatase–rutile phase structure

    SciTech Connect

    Chao, Xiaolian; Wang, Juanjuan; Wang, Zhongming; Zhang, Ting; Yang, Zupei; Li, Guangzhao

    2016-04-15

    Graphical abstract: Titanium dioxide (TiO{sub 2}) with different phase structure had interesting influence on the crystal structure, microstructure, the sintering temperature and electrical properties. - Highlights: • BCZT ceramics were prepared using either anatase or rutile structures as Ti source. • Orthorhombic and tetragonal mixture structure was exhibited by adjusting Ti source. • The optimal properties were observed in BCZT ceramics with rutile titanium dioxide. - Abstract: To research effect of raw materials TiO{sub 2} with the phase structures on the crystal structure, microstructure and electrical properties of lead-free (Ba{sub 0.85}Ca{sub 0.15})(Ti{sub 0.90}Zr{sub 0.10})O{sub 3} (BCZT) ceramics, BCZT ceramics using either anatase or rutile as Ti source were synthesized by solid-state reaction. Titanium dioxide (TiO{sub 2}) with anatase/rutile phase structures had interesting influence on the crystal structure, microstructure and the sintering temperature by the X-ray diffraction and SEM, which also played an important role in improved electrical properties. The BCZT ceramics with rutile titanium dioxide demonstrated optimal piezoelectric and dielectric properties: d{sub 33} = 590 pC/N, k{sub p} = 0.46, ε{sub r} = 2810, tanδ = 0.014 and T{sub c} = 91 °C, which was obviously superior to BCZT ceramics with anatase titanium dioxide.

  2. 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.

  3. 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

    2016-06-24

    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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Electrical and physical properties of composite BaZr0.85Y0.15O3-d-Nd0.1Ce0.9O2-δ electrolytes for intermediate temperature-solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Park, Ka-Young; Lee, Tae-Hee; Jo, Suyeon; Yang, Jayoon; Song, Sun-Ju; Lim, Hyung-Tae; Kim, Jung Hyun; Park, Jun-Young

    2016-12-01

    Co-ionic (H+/O2-) electrolytes are fabricated by compositing both proton conductor (BaZr0.85Y0.15O3-δ, BZY) and oxygen-ion conductor (Nd0.1Ce0.9O2-δ, NDC) for intermediate temperature-solid oxide fuel cells (IT-SOFCs). This hybrid electrolyte decreases the electronic loss of NDC under reducing atmospheres and improves the poor sinterability of BZY. The electronic conduction caused by the NDC reduction is effectively blocked by the BZY in the composite electrolyte, thus offering both advantages of BZY with its high OCV and more rigid electro-chemo-mechanical property. In addition, the composite BZY-NDC electrolyte also exhibits great chemical stability against exposure to steam and CO2. Furthermore, the compositing of BZY and NDC improves the proton conductivity of the electrolytes, and the conductivity of composite electrolyte is higher than that of single BZY at temperatures >600 °C.

  10. Effects of cation-size disorder in (La0.67Ca0.15Sr0.18)1-x(Gd0.67Ba0.33)xCoO3 perovskites

    NASA Astrophysics Data System (ADS)

    Sun, J. R.; Wong, H. K.

    1999-07-01

    Effects of the A-cation disorder on the structural, magnetic and transport properties of the ABO3-type (La0.67Ca0.15Sr0.18)1-x(Gd0.67Ba0.33)xCoO3 (x=0.0, 0.1, 0.2, 0.3, and 0.4) are studied. Based on x-ray diffraction, two crystallographic phases coexist in the compounds, and a progressive transition from rhombohedral structure to orthorhombic structure takes place with increasing x, with which the cation disorder increases. Two resistive transitions, a metal-to-metal and a metal-to-semiconductor, occur subsequently with decreasing temperature, with the upper resistive transition coinciding with a magnetic one. Both resistive transitions vary against x, with the upper one from ~223 to ~190 K and the lower one from ~95 to ~160 K corresponding to a change of x from 0.0-0.3. The presence of cation-size disorder drives the system from the cluster-glass state into the spin-glass state, accompanied by an enhancement of the semiconducting character of the compounds. The weak Jahn-Teller effects and the spin state transition could be responsible for the special cation disorder effects in the Co-based perovskites.

  11. 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.

  12. 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.

  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. Soil aggregates, organic matter turnover and carbon balance in a Mediterranean eroded vineyard

    NASA Astrophysics Data System (ADS)

    Novara, Agata; Lo Papa, Giuseppe; Dazzi, Carmelo; Gristina, Luciano; Cerdà, Artemi

    2014-05-01

    dispersion, were isolated by mechanical shaking of 100 g, air-dried fine earth on a column with sieves of 250 and 63 μm using a Shaker AS 200 Sieve (RETSCH analytical, Haan, Germany) (200-mm sieves, amplitude of 2 cm, frequency of 1.6 Hz and a water flux of 2 litres minute-1). After the physical fractionation, we discriminate three main aggregate-size fractions: >250, 63-250 and <63 μm. Three replicate samples of 5 g of the soil material that we prepared for the fractionation from three different pedons along the slope gradient were incubated at two different depth intervals (Topsoil: 0-15 cm; Subsoil: 35-50 cm). Respiration was monitored during a period of 50 days keeping moisture and temperature constant. Both in topsoil and subsoil layers, particle size distribution in the depositional area shows a decrease of the finest size (<63 μm) respect to the soil in the detachment area. A SOC increase was observed due to depositional processes. Mean Residence Time of SOC strongly decreased in the subsoil particularly in the depositional area corroborating that erosion processes could be a SOC sink. Anyway we should also stress that, considering the estimated "off farm" erosion processes, the carbon budget resulted highly negative. References Barbera, V., Poma, I., Gristina, L., Novara, A., Egli, M. 2013. Long-term cropping systems and tillage management effects on soil organic carbon stock and steady state level of C sequestration rates in a semiarid environment. Land Degradation & Development, 23: 82- 91. DOI 10.1002/ldr.1055 Cerdà, A., Giménez-Morera, A.G., Bodí, M.B. 2009b. Soil and water losses from new citrus orchards growing on sloped soils in the western Mediterranean basin. Earth Surface Processes and Landforms 34, 1822-1830. Dick, W.A., Gregorich, E.G. 2004. Developing and maintaining soil organic matter levels. In: Schjonning, P., Elmholt,S., Christensen, B.T. (Eds.), Managing Soil Quality: Challenges in Modern Agriculture. CAB International, Wallingford, UK, pp

  15. Bells and Essebi: To Be or Not To Be (CM)

    NASA Astrophysics Data System (ADS)

    Kallemeyn, G. W.

    1995-09-01

    The Bells and Essebi carbonaceous chondrites have long been associated with the CM group, although petrographic and isotopic observations have questioned that relationship. Samples of Bells and Essebi were obtained for bulk compositional study by neutron activation analysis (INAA) in an attempt to further fuel the debate on this issue. The current INAA work for Bells is complete, but analysis of Essebi is ongoing, and therefore the data is preliminary. Although CM chondrites typically contain <3 wt% magnetite, Bells and Essebi contain approximately 16 wt% and 11 wt% magnetite, respectively [1]. Both Bells and Essebi seem to have suffered more intense aqueous alteration than typical CM chondrites [2]. Bells has a phyllosilicate matrix composition closer to CI chondrites than CM chondrites [3]. The delta 15N value for Bells is much higher than any of the established carbonaceous chondrite groups[4]. Carbonate material in Essebi has delta 13C compositions (+62 per mil to +80 per mil) higher than the CM mode of +40 per mil to +50 per mil [5]. Both Bells and Essebi have whole rock O-isotope compositions in the CM chondrite range, but Essebi has separated matrix and magnetite values similar to whole rock and magnetite values in CI chondrites [6]. Samples of Bells were from two different stones collected after the fall. One stone was collected the day after the fall, the other was collected several days later after a hurricane went through the area. The samples will be referred to as 'normal' Bells and 'weathered' Bells, respectively. The 'normal' and 'weathered' Bells samples are very similar in composition with a few notable exceptions. The Mg-normalized abundances of Na, K and Br in 'weathered' Bells are markedly depleted relative to 'normal' Bells. The abundance of Ca is also lower to a smaller extent. One must be cautious of compositional studies of late-collected Bells specimens as they may have been altered by the affects of rainwater. Refractory lithophile

  16. Soil warming alters microbial substrate use in alpine soils.

    PubMed

    Streit, Kathrin; Hagedorn, Frank; Hiltbrunner, David; Portmann, Magdalena; Saurer, Matthias; Buchmann, Nina; Wild, Birgit; Richter, Andreas; Wipf, Sonja; Siegwolf, Rolf T W

    2014-04-01

    Will warming lead to an increased use of older soil organic carbon (SOC) by microbial communities, thereby inducing C losses from C-rich alpine soils? We studied soil microbial community composition, activity, and substrate use after 3 and 4 years of soil warming (+4 °C, 2007-2010) at the alpine treeline in Switzerland. The warming experiment was nested in a free air CO2 enrichment experiment using depleted (13)CO2 (δ(13)C = -30‰, 2001-2009). We traced this depleted (13)C label in phospholipid fatty acids (PLFA) of the organic layer (0-5 cm soil depth) and in C mineralized from root-free soils to distinguish substrate ages used by soil microorganisms: fixed before 2001 ('old'), from 2001 to 2009 ('new') or in 2010 ('recent'). Warming induced a sustained stimulation of soil respiration (+38%) without decline in mineralizable SOC. PLFA concentrations did not reveal changes in microbial community composition due to soil warming, but soil microbial metabolic activity was stimulated (+66%). Warming decreased the amount of new and recent C in the fungal biomarker 18:2ω6,9 and the amount of new C mineralized from root-free soils, implying a shift in microbial substrate use toward a greater use of old SOC. This shift in substrate use could indicate an imbalance between C inputs and outputs, which could eventually decrease SOC storage in this alpine ecosystem.

  17. Assessment of sulfide production risk in soil during the infiltration of domestic wastewater treated by a sulfur-utilizing denitrification process.

    PubMed

    Ghorbel, L; Coudert, L; Gilbert, Y; Mercier, G; Blais, J F

    2016-10-01

    This study aimed to determine the potential of sulfide generation during infiltration through soil of domestic wastewater treated by a sulfur-utilizing denitrification process. Three types of soil with different permeability rates (K s = 0.028, 0.0013, and 0.00015 cm/s) were investigated to evaluate the potential risk of sulfur generation during the infiltration of domestic wastewater treated by a sulfur-utilizing denitrification system. These soils were thoroughly characterized and tested to assess their capacity to be used as drainages for wastewaters. Experiments were conducted under two operating modes (saturated and unsaturated). Sulfate, sulfide, and chemical oxygen demand (COD) levels were determined over a period of 100 days. Despite the high concentration of sulfates (200 mg/L) under anaerobic conditions (ORP = -297 mV), no significant amount of sulfide was generated in the aqueous (<0.2 mg/L) or gaseous (<0.15 ppm) phases. Furthermore, the soil permeability did not have a noticeable effect on the infiltration of domestic wastewater treated by a sulfur-utilizing denitrification system due to low contents of organic matter (i.e., dissolved organic carbon, DOC). The autotrophic denitrification process used to treat the domestic wastewater allowed the reduction of the concentration of biochemical oxygen demand (BOD5) below 5 mg/L, of DOC below 7 mg/L, and of COD below 100 mg/L.

  18. Estimating toxic damage to soil ecosystems from soil organic matter profiles

    USGS Publications Warehouse

    Beyer, W.N.

    2001-01-01

    Concentrations of particulate and total organic matter were measured in upper soil profiles at 26 sites as a potential means to identify toxic damage to soil ecosystems. Because soil organic matter plays a role in cycling nutrients, aerating soil, retaining water, and maintaining tilth, a significant reduction in organic matter content in a soil profile is not just evidence of a change in ecosystem function, but of damage to that soil ecosystem. Reference sites were selected for comparison to contaminated sites, and additional sites were selected to illustrate how variables other than environmental contaminants might affect the Soil organic matter profile. The survey was undertaken on the supposition that environmental contaminants and other stressors reduce the activity of earthworms and other macrofauna, inhibiting the incorporation of organic matter into the soil profile. The profiles of the unstressed soils showed a continuous decrease in organic matter content from the uppermost mineral soil layer (0-2.5 cm) down to 15 cm. Stressed soils showed an abrupt decrease in soil organic matter content below a depth of 2.5 cm. The 2.5-5.0 cm layer of stressed soils--such as found in a pine barren, an orchard, sites contaminated with zinc, and a site with compacted soil--had less than 4% total organic matter and less than 1% particulate organic matter. However, damaged soil ecosystems were best identified by comparison of their profiles to the profiles of closely matched reference soils, rather than by comparison to these absolute values. The presence or absence of earthworms offered a partial explanation of observed differences in soil organic matter profiles.

  19. Soil carbon stock and soil characteristics at Tasik Chini Forest Reserve, Pahang, Malaysia

    NASA Astrophysics Data System (ADS)

    Nur Aqlili Riana, R.; Sahibin A., R.

    2015-09-01

    This study was carried out to determine soil carbon stock and soil characteristic at Tasik Chini Forest Reserve (TCFR), Pahang. A total of 10 (20 m x 25 m) permanent sampling plot was selected randomly within the area of TCFR. Soil samples were taken from all subplots using dutch auger based on soil depth of 0-20cm, 20-40cm, 40-60cm. Soil parameters determined were size distribution, soil water content, bulk density, organic matter, organic carbon content, pH and electrical conductivity. All parameters were determined following their respective standard methods. Results obtained showed that the soil in TCFR was dominated by clay texture (40%), followed by sandy clay loam (30%), loam (20%). Silty clay, clay loam and sandy loam constitutes about 10% of the soil texture. Range of mean percentage of organic matter and bulk density are from 2.42±0.06% to 11.64±0.39% and 1.01 to 1.04 (gcm-ł), respectively. Soil pH are relatively very acidic and mean of electrical conductivity is low. Soil carbon content ranged from 0.83±0.03 to 1.87±0.41%. All soil parameter showed a decreasing trend with depth except electrical conductivity. ANOVA test of mean percentage of organic matter, soil water content, soil pH and electrical conductivity showed a significant difference between plot (p<0.05). However there are no significant difference of mean bulk density between plots (p>0.05). There are no significant difference in mean percentage of soil water content, organic matter and bulk density between three different depth (p>0.05). There were a significant difference on percentage of soil carbon organic between plots and depth. The mean of soil organic carbon stock in soil to a depth of 60 cm calculated was 35.50 t/ha.

  20. Soil infrastructure evolution and its effect on water transfer processes under contrasted tillage systems with preliminary results

    NASA Astrophysics Data System (ADS)

    Parvin, Nargish; Degré, Aurore; Chélin, Marie; Hiel, Marie-Pierre; Garré, Sarah; Bodson, Bernard

    2014-05-01

    soil structure are usually noticed in the range of 9.8 to 98 hPa, so, we can conclude that there is certainly structural change between WP and conservation practices of ST, NI and NO. In addition, Hwr in ST also shows increase in macroporosity than NI. In our study, there will be also soil moisture sensors (Decagon 10HS, 5TM and ML3 Thetaprobe) to capture the total soil moisture networks in the field under four different trials. The soils from the different trials and also from different depths (0-15, 25-30 and 50-60 cm) were used for zone specific calibration of the sensors. All the experiments will be repeated twice a year. For the specific spatio-temporal comparison, the monitoring results from electrical resistance tomography will be available from the collaborated project of the same faculty.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. POLYSHIFT Communications Software for the Connection Machine System CM-200

    DOE PAGES

    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

  7. 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.

  8. Soil adherence to human skin

    SciTech Connect

    Driver, J.H.; Konz, J.J.; Whitmyre, G.K. )

    1989-12-01

    Dermal exposure to soils contaminated with toxic chemicals represents a potential public health hazard. These soils, contaminated with chemicals such as PCBs and dioxins, may be found at various locations throughout the US. Furthermore, dermal contact with pesticide-containing particles and contaminated soil particles is of importance for exposures to agricultural workers who reenter fields after pesticide application. With respect to dermal exposure to pesticide-contaminated particulate matter, several occurrences of human toxicity to ethyl parathion in citrus groves have been reported. These exposures resulted from dermal contact with high concentrations of the toxic transformation product paraoxon in soil dust contaminated as a result of application of pesticide to the overhead foliage of trees. To assess dermal exposure to chemically-contaminated soil at sites of concern, dermal adherence of soil must be determined prior to the assessment of dermal absorption. The purpose of the experiment reported herein was to determine the amount of soil (mg/cm{sup 2}) that adheres to adult hands under various soil conditions. These conditions include the type of soil, the organic content of the soil, and the particle size of the soil.

  9. Soil Temperature Reemergence in Permafrost

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Schaefer, K.

    2007-12-01

    Soil temperature reemergence is the disappearance and subsequent reappearance of near surface soil temperature anomalies, driven by soil freeze-thaw processes. Reemergence of past soil temperature anomalies is a new class of time-delayed, land-atmosphere feedbacks influencing surface fluxes of latent and sensible heat. Anomalous energy is stored, isolated from diffusion processes, as variations in latent heat of fusion. Schaefer et al. [2007] found that past soil temperature anomalies in seasonally frozen soils are stored as variations in the amount of ground ice and can reemerge at the surface after soil thaw in spring. Schaefer et al. [2007] also hypothesized that temperature anomalies in permafrost would be stored as variations in the active layer depth, reappearing after the soil column completely freezes in winter. Essentially, a warm summer produces a deeper active layer, which requires more energy to freeze in autumn, resulting in warmer soils in winter. Here, we explore this hypothesis using statistical analysis of long-term, in situ soil temperature measurements at 37 permafrost hydro-meteorological stations across Siberia. The observations span 30-40 years at depths of 2-320 cm. We also use a simple soil thermodynamic model with phase changes to explore the detailed thermodynamic processes driving temperature reemergence in permafrost.

  10. How accurately can 21cm tomography constrain cosmology?

    NASA Astrophysics Data System (ADS)

    Mao, Yi; Tegmark, Max; McQuinn, Matthew; Zaldarriaga, Matias; Zahn, Oliver

    2008-07-01

    There is growing interest in using 3-dimensional neutral hydrogen mapping with the redshifted 21 cm line as a cosmological probe. However, its utility depends on many assumptions. To aid experimental planning and design, we quantify how the precision with which cosmological parameters can be measured depends on a broad range of assumptions, focusing on the 21 cm signal from 6cm tomography measured the matter power spectrum directly. A future square kilometer array optimized for 21 cm tomography could improve the sensitivity to spatial curvature and neutrino masses by up to 2 orders of magnitude, to ΔΩk≈0.0002 and Δmν≈0.007eV, and give a 4σ detection of the spectral index running predicted by the simplest inflation models.

  11. The future of primordial features with 21 cm tomography

    NASA Astrophysics Data System (ADS)

    Chen, Xingang; Meerburg, P. Daniel; Münchmeyer, Moritz

    2016-09-01

    Detecting a deviation from a featureless primordial power spectrum of fluctuations would give profound insight into the physics of the primordial Universe. Depending on their nature, primordial features can either provide direct evidence for the inflation scenario or pin down details of the inflation model. Thus far, using the cosmic microwave background (CMB) we have only been able to put stringent constraints on the amplitude of features, but no significant evidence has been found for such signals. Here we explore the limit of the experimental reach in constraining such features using 21 cm tomography at high redshift. A measurement of the 21 cm power spectrum from the Dark Ages is generally considered as the ideal experiment for early Universe physics, with potentially access to a large number of modes. We consider three different categories of theoretically motivated models: the sharp feature models, resonance models, and standard clock models. We study the improvements on bounds on features as a function of the total number of observed modes and identify parameter degeneracies. The detectability depends critically on the amplitude, frequency and scale-location of the features, as well as the angular and redshift resolution of the experiment. We quantify these effects by considering different fiducial models. Our forecast shows that a cosmic variance limited 21 cm experiment measuring fluctuations in the redshift range 30 <= z <= 100 with a 0.01-MHz bandwidth and sub-arcminute angular resolution could potentially improve bounds by several orders of magnitude for most features compared to current Planck bounds. At the same time, 21 cm tomography also opens up a unique window into features that are located on very small scales.

  12. 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.

  13. OH 18 cm TRANSITION AS A THERMOMETER FOR MOLECULAR CLOUDS

    SciTech Connect

    Ebisawa, Yuji; Inokuma, Hiroshi; Yamamoto, Satoshi; Sakai, Nami; Menten, Karl M.; Maezawa, Hiroyuki

    2015-12-10

    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 H{sub 2} densities (10{sup 2}–10{sup 7} cm{sup −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 H{sub 2} 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.

  14. 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.

  15. 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.

  16. The importance of ingested soils in supplying fluorine and lead to sheep grazing contaminated pastures in the Peak District mining area of Derbyshire, UK.

    PubMed

    Abrahams, Peter W; Blackwell, Nia L

    2013-12-01

    For sheep grazing pastures in areas of mineralisation and former metalliferous mining activity, an excessive intake of potentially harmful elements (PHEs) such as fluorine (F) and lead (Pb) can result in clinical and subclinical toxicity. The prime aim of our work was to calculate the intakes of both of these PHEs by sheep grazing pastures in the mineralised/mined Peak District area of Derbyshire. The bi-monthly sampling of topsoils (0-15 cm depth) and the faeces of sheep from fields at seven farms was undertaken for a 1-year period. These samples were analysed for titanium that allowed the rates of soil ingestion (and hence also herbage ingestion since we assume that the sheep have an overall diet of 1 kg dry matter (DM)/day) to be determined. Our findings were then combined with previously published soil and soil-free pasture herbage F and Pb concentrations determined from the seven farms to calculate the intakes of both PHEs. The results show seasonal variations of soil ingestion at the seven farms ranging from <0.1 to 20.1 % of the DM intake (median=3 %), with the highest rates of ingestion being associated with the winter-spring (i.e. December-April) period. Our calculations show that at some farms, sheep can be exposed to dietary concentrations in excess of recommended guidelines potentially throughout the whole year, though livestock movement to less-contaminated pastures would lessen any toxic impact. Because the soil concentrations are greater than those associated with soil-free pasture herbage, ingested soils are the main dietary source of Pb and (especially) F to sheep. However, subjecting freshly sampled topsoils to sequential extraction procedures undertaken in the laboratory indicates that the majority of Pb and (especially) F may not be readily soluble in the ovine digestion system, so reducing the quantities of both PHEs available for absorption.

  17. 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.

  18. Am/Cm Vitrification Process: Vitrification Material Balance Calculations

    SciTech Connect

    Smith, F.G.

    2000-08-15

    This report documents material balance calculations for the Americium/Curium vitrification process and describes the basis used to make the calculations. The material balance calculations reported here start with the solution produced by the Am/Cm pretreatment process as described in ``Material Balance Calculations for Am/Cm Pretreatment Process (U)'', SRT-AMC-99-0178 [1]. Following pretreatment, small batches of the product will be further treated with an additional oxalic acid precipitation and washing. The precipitate from each batch will then be charged to the Am/Cm melter with glass cullet and vitrified to produce the final product. The material balance calculations in this report are designed to provide projected compositions of the melter glass and off-gas streams. Except for decanted supernate collected from precipitation and precipitate washing, the flowsheet neglects side streams such as acid washes of empty tanks that would go directly to waste. Complete listings of the results of the material balance calculations are provided in the Appendices to this report.

  19. FURTHER EVALUATIONS OF RADIONUCLIDE PHYTOEXTRACTION FEASIBILITY USING SOILS FROM THE U.S. DEPARTMENT OF ENERGY COMPLEX

    SciTech Connect

    Jay Cornish

    1999-01-01

    Fiscal Year 98 (FY98) radionuclide phytoextraction studies involved resumption of the radiocesium-137 ({sup 137}Cs) investigations at Brookhaven National Laboratory (BNL) and the total uranium (U{sub t}) investigations at the Fernald Environmental Management Project (FEMP) site. This project was a collaborative effort involving scientists and engineers from MSE Technology Applications, Inc.; the US Department of Agriculture (USDA) Plant Growth Laboratory at Cornell University; Phytotech, Inc.; BNL; and FEMP. In both cases, the essential goal was to improve bioavailability, uptake, and transport of these contaminants from soil to leaf-and-stalk biomass (LSB). In particular, the practical goal was to demonstrate that about half the radionuclide contaminant mass present in near surface [{le}30 centimeters (cm) below ground surface (bgs)] soils could be transferred into LSB in approximately 5 years. Based on previous (1996) study results, it would require concentration ratios (CRs) of at 5-to-10 to achieve this goal. In addition, the rate of {sup 137}Cs removal must be {ge} 2.3% per year{sup -1} [i.e., (0.693/30.2) {center_dot} 100] to equal or exceed the loss of this radionuclide through natural decay. This report first presents and discusses the results from greenhouse and field evaluations of {sup 137}Cs uptake from rooting zone soils (0-15 cm bgs) located near the Medical/Biological Research Building (No. 490) at BNL. Contamination of this site resulted from the use of near surface soils originating at the former Hazardous Waste Management Facility (HWMF), which served as a source of landscaping materials for erosion control, etc. Project personnel from USDA evaluated various combinations of nonradioactive solutions of cesium chloride (CsCl) and rubidium chloride, ammonium nitrate solution (NH{sub 4}NO{sub 3}), and humic acid suspensions to enhance and sustain {sup 137}Cs levels in soil solution. Of the plants grown in such amended soils, the highest CRs occurred

  20. Assessment of elemental mobility in soil using a fluidised bed approach with on-line ICP-MS analysis.

    PubMed

    Beeston, Michael Philip; Glass, Hylke Jan; van Elteren, Johannes Teun; Slejkovec, Zdenka

    2007-09-19

    A new method has been developed to analyse the mobility of elements within soils employing counter-current flow soil contacting in a fluidised bed (FB) column. This method alleviates the problem of irreproducible peaks suffered by state-of-the-art micro-column techniques as a result of particle compaction. Reproducible extraction profiles are produced through the leaching of soil with a linear gradient of 0.05 mol L(-1) ammonium sulphate to 0.11 mol L(-1) acetic acid using a high pressure liquid chromatography (HPLC) quaternary pump, and the continuous monitoring of the elements in the leachate with inductively coupled plasma mass spectrometry (ICP-MS). Quantification of the procedure is achieved with an external flow injection (FI) calibration method. Flow rate and FB column length were investigated as critical parameters to the efficiency of the extraction methodology. It was found that an increase in the column length from 10 to 20 cm using a flow rate of 0.15 mL min(-1) produced the same increase in extracted elemental concentration as an increase in flow rate from 0.15 to 0.30 mL min(-1). In both examples, the increase in the concentration of elements leached from the soil may be ascribed to the increase in the concentration gradient between the solid and liquid. The exhaustive nature of the technique defines the maximum leachable concentration within the operationally defined leaching parameters of the exchangeable phase, providing a more accurate assessment of the risk associated with the elements in the soil for the phase providing the greatest risk to the environment. The multi-elemental high sensitivity nature of the on-line detector provides an accurate determination of the associations present between the elements in the soil, and the identification of multiple phases within the exchangeable phase through the presence of multiple peaks in the extraction profiles. It is possible through the deconvolution of these extraction profiles that the

  1. Long-term effects of deep soil loosening on root distribution and soil physical parameters in compacted lignite mine soils

    NASA Astrophysics Data System (ADS)

    Badorreck, Annika; Krümmelbein, Julia; Raab, Thomas

    2015-04-01

    Soil compaction is a major problem of soils on dumped mining substrates in Lusatia, Germany. Deep ripping and cultivation of deep rooting plant species are considered to be effective ways of agricultural recultivation. Six years after experiment start, we studied the effect of initial deep soil loosening (i.e. down to 65 cm) on root systems of rye (Secale cereale) and alfalfa (Medicago sativa) and on soil physical parameters. We conducted a soil monolith sampling for each treatment (deep loosened and unloosened) and for each plant species (in three replicates, respectively) to determine root diameter, length density and dry mass as well as soil bulk density. Further soil physical analysis comprised water retention, hydraulic conductivity and texture in three depths. The results showed different reactions of the root systems of rye and alfalfa six years after deep ripping. In the loosened soil the root biomass of the rye was lower in depths of 20-40 cm and the root biomass of alfalfa was also decreased in depths of 20-50 cm together with a lower root diameter for both plant species. Moreover, total and fine root length density was higher for alfalfa and vice versa for rye. The soil physical parameters such as bulk density showed fewer differences, despite a higher bulk density in 30-40cm for the deep loosened rye plot which indicates a more pronounced plough pan.

  2. 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.

  3. 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.

  4. Identifying the Distribution of Al 3+ in LiNi 0.8 Co 0.15 Al 0.05 O 2

    SciTech Connect

    Trease, Nicole M.; Seymour, Ieuan D.; Radin, Maxwell D.; Liu, Haodong; Liu, Hao; Hy, Sunny; Chernova, Natalya; Parikh, Pritesh; Devaraj, Arun; Wiaderek, Kamila M.; Chupas, Peter J.; Chapman, Karena W.; Whittingham, M. Stanley; Meng, Ying Shirley; Van der Van, Anton; Grey, Clare P.

    2016-11-22

    The doping of Al into layered Li transition metal (TM) oxide cathode materials, LiTMO2, is known to improve the structural and thermal stability, although the origin of the enhanced properties is not well understood. The effect of aluminum doping on layer stabilization has been investigated using a combination of techniques to measure the aluminum distribution in layered LiNi0.8Co0.15Al0.05O2 (NCA) over multiple length scales with 27Al and 7Li MAS NMR, local electrode atom probe (APT) tomography, X-ray and neutron diffraction, DFT, and SQUID magnetic susceptibility measurements. APT ion maps show a homogenous distribution of Ni, Co, Al and O2 throughout the structure at the single particle level in agreement with the high-temperature phase diagram. 7Li and 27Al NMR indicates that the Ni3+ ions undergo a dynamic Jahn-Teller (JT) distortion. 27Al NMR spectra indicate that the Al reduces the strain associated with the JT distortion, by preferential electronic ordering of the JT long bonds directed toward the Al3+ ion. The ability to understand the complex atomic and orbital ordering around Al3+ demonstrated in the current method will be useful for studying the local environment of Al3+ in a range of transition metal oxide battery materials.

  5. Analysis of Low Excitation HDO Transitions toward the High-mass Star-forming Regions G34.26+0.15, W51e1/e2, and W49N

    NASA Astrophysics Data System (ADS)

    Kulczak-Jastrzȩbska, Magda

    2017-02-01

    We present observations of the ground state 10,1–00,0 rotational transition of HDO at 464.925 GHz and the 11,0–10,1 transition at 509.292 GHz, toward three high-mass star-forming regions: G34.26+0.15, W49N, and W51e1/e2, carried out with the Caltech Submillimeter Observatory. For the first time, the latter transition is observed from the ground. The spectra are modeled, together with observations of higher-energy HDO transitions, as well as submillimeter dust continuum fluxes from the literature, using a spherically symmetric radiative transfer model to derive the radial distribution of the HDO abundance in the target sources. The abundance profile is divided into an inner hot core region, with kinetic temperatures higher than 100 K, and a cold outer envelope with lower kinetic temperatures. The derived HDO abundance with respect to H2 is (0.3–3.7) × 10‑8 in the hot inner region (T > 100 K) and (7.0–10.0) × 10‑11 in the cold outer envelope. We also used two {{{H}}}218{{O}} fundamental transitions to constrain the H2O abundances in the outer envelopes. The HDO/H2O ratios in these cold regions are found to be (1.8–3.1) × 10‑3 and consequently are higher than in the hot inner regions of these sources.

  6. Defect structure and ionic conductivity of Ca{sub 1-x}Sc{sub x}F{sub 2+x} (0.02 {<=} x {<=} 0.15) single crystals

    SciTech Connect

    Sulyanova, E. A. Molchanov, V. N.; Sorokin, N. I.; Karimov, D. N.; Sulyanov, S. N.; Sobolev, B. P.

    2009-07-15

    Single crystals of the Ca{sub 1-x}Sc{sub x}F{sub 2+x}(x = 0.106, 0.132, 0.156) solid solutions (CaF{sub 2} structure type, space group Fm3-barm) are investigated using X-ray diffraction. It is revealed that the crystals under investigation contain vacancies in the 8c positions and interstitial fluorine ions in the 48i positions. The coordination number of Sc{sup 3+} ions in the structure of the Ca{sub 1-x}Sc{sub x}F{sub 2+x} solid solutions is equal to eight. The specific features of the concentration dependences of the ionic conductivity and the activation energy of ion transfer for the Ca{sub 1-x}Sc{sub x}F{sub 2+x}(0.02 {<=} x {<=} 0.15) solid solutions are explained in the framework of the percolation model of conducting 'defect regions.' The percolation threshold equal to 3-5 mol % ScF{sub 3} corresponds to the model of [Ca{sub 14-n}Sc{sub n}F{sub 68}] octacubic clusters containing fluorine ions in the 48i positions. The ionic conductivity of the Ca{sub 1-x}Sc{sub x}F{sub 2+x} solid solutions is analyzed in comparison with the change in this characteristic for the series of Ca{sub 0.8}R{sub 0.2}F{sub 2.2} crystals with rare-earth elements.

  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. Enhancement in the electrochemical performance of zirconium/phosphate bi-functional coatings on LiNi0.8Co0.15Mn0.05O2 by the removal of Li residuals.

    PubMed

    Park, Kwangjin; Park, Jun-Ho; Hong, Suk-Gi; Choi, Byungjin; Seo, Seung-Woo; Park, Jin-Hwan; Min, Kyoungmin

    2016-10-26

    The effect of bi-functional coatings consisting of Zr and phosphate (P) on the electrochemical performance of Li1.0Ni0.8Co0.15Mn0.05O2 (NCM) has been investigated. The presence of various types of Zr and P compounds such as oxides (ZrO2 and Li2ZrO3) and phosphates (Zr2P2O9, ZrP2O7 and LiZr2(PO4)3) in the coating was confirmed by experiments as well as density functional theory (DFT) calculations. When the NCM samples were coated with the Zr/P hybrid material, the cycle retention and the amount of removed Li residuals (LiOH, Li2CO3) were enhanced by the synergistic effect from Zr and P. The NCM sample coated with a Zr/P layer with a Zr/P ratio of 1 : 1 exhibited an increase in the initial capacity (209.3 mA h g(-1)) compared to the pristine sample (207.4 mA h g(-1)) at 0.1C, owing to the formation of the coating layer. The capacity retention of the Zr/P coated sample (92.4% at the 50th cycle) was also improved compared to that of the pristine NCM sample (90.6% at the 50th cycle). Moreover, the amount of Li residuals in the Zr/P coated NCM sample was greatly reduced from 3693 ppm (pristine NCM) to 2525 ppm (Zr/P = 5 : 5).

  9. 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.

  10. The electronic and magnetic properties of La{sub 0.85}Zr{sub 0.15}MnO{sub 3} deposited on SrTiO{sub 3} and MgO substrates

    SciTech Connect

    Deshpande, N. G.; Weng, C. H.; Wang, Y. F.; Shao, Y. C.; Cheng, C. Q.; Ling, D. C. E-mail: wfpong@mail.tku.edu.tw; Hsueh, H. C.; Du, C. H.; Pong, W. F. E-mail: wfpong@mail.tku.edu.tw; Tsai, H. M.; Pao, C. W.; Lin, H. J.; Lee, J. F.; Chiou, J. W.; Tsai, M. H.

    2014-06-21

    The electronic and magnetic properties of tetravalent-ion-doped La{sub 0.85}Zr{sub 0.15}MnO{sub 3} (LZMO) thin films that were epitaxially grown on SrTiO{sub 3} (STO) and MgO substrates were studied using temperature-dependent x-ray diffraction (XRD), x-ray absorption near-edge structure, x-ray linear dichroism, and x-ray magnetic circular dichroism at the Mn L{sub 3,2}- and K-edge. XRD studies reveal that the LZMO thin films have compressive and tensile strains (along the c-axis) on the STO and MgO substrates, respectively. As the temperature is reduced from room temperature to below magnetic transition temperature, the preferentially occupied Mn majority-spin e{sub g} orbital changes from the in-plane d{sub x}{sup 2}{sub -y}{sup 2} to the out-of-plane d{sub 3z}{sup 2}{sub -r}{sup 2} orbital for LZMO/STO, and vice versa for LZMO/MgO. Experimental results suggest that the new hopping path that is mediated by the Mn{sup 2+} ions triggers a stronger d{sub 3z}{sup 2}{sub -r}{sup 2} orbital ordering of Mn{sup 3+} ions and enhances the ferromagnetic coupling between the Mn spin moments of t{sub 2g} electrons in LZMO/STO, whereas the strong tensile strain stabilizes the d{sub x}{sup 2}{sub -y}{sup 2} orbital by inducing lattice distortions of the MnO{sub 6} octahedra in LZMO/MgO.

  11. 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

    2015-09-09

    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).

  12. Carbon Sequestration in Reclaimed Mined Soils of Ohio

    SciTech Connect

    M.K. Shukla; R. Lal

    2005-01-01

    Assessment of soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS) is important for preserving environmental quality and increasing agronomic yields. The experimental sites were characterized by distinct age chronosequences of reclaimed minesoil and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites are owned and maintained by Americal Electrical Power. These sites were reclaimed (1) with topsoil application, and (2) without topsoil application, and were under continuous grass or forest cover. In this report results are presented from the sites reclaimed without topsoil application between 1956 and 1969. Three sites are under continuous grass cover and the three under forest cover since reclamation. Three core and three bulk soil samples were collected from each site from three slope positions (upper; middle, and lower) for 0-15 cm and 15-30 cm depths, and texture, pH and electrical conductivity (EC), soil bulk density ({rho}{sub b}), SOC, total nitrogen (TN) stocks were determined. No differences in sand and clay contents, bulk density, SOC and TN stocks were observed within different slope positions within each site. However, sand [R56-G (17.1%) < R69-G (29.1%) = R62-G (29.1%)], and silt [R56-G (58.3%) > R69-G (47.7%)] contents, bulk density [R62-G (1.25 Mg ha{sup -1}) > R69-G (0.94 Mg ha{sup -1}) = R62-G (0.90 Mg ha{sup -1})] varied significantly on the upper slope position among sites under continuous grass cover. Smaller but significant differences were also observed for pH [R69-G (8.3) > R56-G (7.7) = R62-G (7.9)] and EC [R56-G (0.66 dS m{sup -1}) > R62-G (0.25 dS m{sup -1}) = R69-G (0.24 dS m{sup -1})] on upper slope positions among sites under grass. Comparing all sites stochastically, sand and clay contents were similar among all sites except R62-F for both depths. Similarly, soil bulk density was also similar among all sites except R62-G for both depths. There were few differences in total

  13. 10 cm x 10 cm Single Gas Electron Multiplier (GEM) X-ray Fluorescence Detector for Dilute Elements

    NASA Astrophysics Data System (ADS)

    Shaban, E. H.; Siddons, D. P.; Seifu, D.

    2014-03-01

    We have built and tested a 10 cm × 10 cm single Gas Electron Multiplier (GEM) X-ray detector to probe dilute amounts of Fe in a prepared sample. The detector uses Argon/Carbon Dioxide (75/25) gas mixture flowing at a slow rate through a leak proof Plexi-glass enclosure held together by O-rings and screws. The Fluorescence X-ray emitted by the element under test is directed through a Mylar window into the drift region of the detector where abundant gas is flowing. The ionized electrons are separated, drifted into the high electric field of the GEM, and multiplied by impact ionization. The amplified negatively charged electrons are collected and further amplified by a Keithley amplifier to probe the absorption edge of the element under test using X-ray absorption spectroscopy technique. The results show that the GEM detector provided good results with less noise as compared with a Silicon drift detector (SDD).

  14. Does strip-tillage could limit the drop of yields on soils of reduced depth of profiles in loess areas?

    NASA Astrophysics Data System (ADS)

    Rejman, Jerzy; Rafalska-Przysucha, Anna; Jadzczyszyn, Jan; Rodzik, Jan

    2016-04-01

    Strip tillage restrict a tillage operation to seed rows and enables a combination of tillage, sowing and application of fertilizers during one pass of agricultural machines. The practice decreases the costs of fuel and limits the risk of water erosion by the increase of infiltration of soil water. In the studies, we put a hypothesis that strip tillage is a tool to increase the yields on soils of reduced profiles. Studies were carried out in the loess area of the Lublin Upland (Poland). The site is cultivated from the beginning of the 18th century, and strip tillage is performed from 2008. All plant residues is left after harvest in the field and mixed with the soil by disc harrow. Measurements of solum depth (Ap-BC), soil properties and parameters of plant growth were carried out in 108 points in the field of the area of 4 ha. Crops included winter wheat (2014) and maize (2015). Studies showed that the profiles of Haplic Luvisol were largely truncated or overbuilt due to erosion and moldboard plow in the past. Solum depth ranged from 0.2 to 3.6 m (mean=1.29 m, CV=64%), and soils with the non-eroded, slightly, moderately, severely, very severely eroded and depositional profiles represented 13, 32, 10, 5, 8 and 32% of total number of cores, respectively. In a result of modification of profiles, clay content ranged from 84 to 222 (145; 16%) in the layer of 0-15 cm, whereas SOC concentration remained on relatively low level and ranged from 4.3 to 16.8 g/kg (9.1; 21.4%). Soil water content (SWC) within depth of 1-m profile was differentiated at the start of measurements in the middle of June 2015. The SWC was the highest in non-eroded and depositional soils and the smallest in severely and very severely eroded soils. The difference of 5% has maintained during the whole growing season and did not affect the growth of plants till the phase of flowering. Then, the plants on shallower soils passed quicker to the next phenological phases in comparison to the plants on deeper

  15. The dynamics of soil aggregate breakdown in water in response to landuse as measured with laser diffraction technique

    NASA Astrophysics Data System (ADS)

    Oyedele, D. J.; Pini, R.; Sparvoli, E.; Scatena, M.

    2012-04-01

    The Mastersizer 2000G (Malvern Instruments) Diffraction Instrument was used to assess and quantify the breakdown of soil aggregates and compute wet aggregate stability indices. The study was aimed at evolving a novel rapid method of determining soil aggregate stability. Bulk surface (0-15 cm) soil samples were collected under 5 different land uses in the Teaching and Resrach Farm of Obafemi Awolowo University, Ile-Ife, Nigeria. About 0.5g of the soils aggregates (0.5 -1 mm diameter) were evaluated in the laser diffractometer with the stirrer operated at 500 rpm and the pump at 1800 rpm. The different size aggregates and particles of sand silt and clay were quantified periodically. Water stable aggregates greater than 250 µm (WSA>250), water stable aggregates less than 250 µm (WSA<250), water dispersible clay index (WDI), and mean volume diameter (MVD) among others were computed from the laser diffraction data. The values were compared with the classical Yoder wet sieving technique. The WSA>250 was significantly higher on the soils under Forest (FR), Cacao (CC), Teak (TK) and Oil Palm (OP) plantations, while it was significantly lowest under no-tillage (NT) and continuous cultivation (CT). The pasture (PD) was not significantly different from either the cultivated and the non-cultivated soils. Conversely, the WSA<250 and water dispersible clay index was highest in the cultivated soils (CT and NT) and lowest in the non-cultivated soils (FR, TK, CC and OP) while the PD was in-between. The MVD also followed a similar trend as the WSA>250. The wet sieving water stable aggregates index (WSI>250) was significantly correlated with WSA>250 (r = 0.75), MVD (r = 0.75), WDI (r = -0.68) and WSA<250 (r = - 0.73). All the laser diffraction measured aggregation indices were significantly correlated with the organic matter contents of the soils. Thus the laser diffraction promises a rapid and comprehensive method of evaluation of soil aggregate stability.

  16. 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.

  17. Changes in the properties of soils in a solonetz soil complex thirty years after reclamation

    NASA Astrophysics Data System (ADS)

    Kalinichenko, V. P.; Sharshak, V. K.; Mironchenko, S. F.; Chernenko, V. V.; Ladan, E. P.; Genev, E. D.; Illarionov, V. V.; Udalov, A. V.; Udalov, V. V.; Kippel, E. V.

    2014-04-01

    The long-term (30 year) dynamics of a solonetz soil complex composed of solonetzic light chestnut soils and chestnut solonetzes under standard conditions and with the application of agromeliorative measures are considered. When the standard zonal agricultural practice is used, the soils of the solonetzic complex have unfavorable agrophysical, chemical, and physicochemical properties and low productivity. After 30 years of the standard three-level tillage of the soils to a depth of 40-45 cm, the productivity of the biogeocenosis decreased. Thirty years after a single rotary-milling subsoil treatment of the 20- to 45-cm soil layer using a milling tool FS-1.3, there were no morphological features pointing to the restoration of the solonetzic process. The humus content in the 0-to 20-cm and 20-to 40-cm soil layers was 2.3 and 1.7%, respectively; the content of adsorbed Na+ in the 20-to 30-cm layer was 11.6% of the total exchange capacity, or 38% lower than its content in the reference soil. The additional yield reached 30-70% and more of that obtained with the standard agricultural technology used during the whole period under investigation. The method of systems biogeotechnology (systems bio-geo engineering) is proposed as a method for the preventive control of soil evolution and the maintenance of the stability and high productivity of the soil cover.

  18. Soil warming affects soil organic matter chemistry of all density fractions of a mountain forest soil

    NASA Astrophysics Data System (ADS)

    Schnecker, Jörg; Wanek, Wolfgang; Borken, Werner; Schindlbacher, Andreas

    2016-04-01

    Rising temperatures enhance microbial decomposition of soil organic matter (SOM) and increase thereby the soil CO2 efflux. Elevated microbial activity might differently affect distinct SOM pools, depending on their stability and accessibility. Soil fractions derived from density fractionation have been suggested to represent SOM pools with different turnover times and stability against microbial decomposition. We here investigated the chemical and isotopic composition of bulk soil and three different density fractions of forest soils from a long term warming experiment in the Austrian Alps. At the time of sampling the soils in this experiment had been warmed during the snow-free period for 8 consecutive years. During that time no thermal adaptation of the microbial community could be identified and CO2 release from the soil continued to be elevated by the warming treatment. Our results which included organic C content, total N content, δ13C, δ 14C, δ 15N and the chemical composition, identified by pyrolysis-GC/MS, showed no significant differences in bulk soil between warming treatment and control. The differences in the three individual fractions (free particulate organic matter, occluded particulate organic matter and mineral associated organic matter) were mostly small and the direction of warming induced change was variable with fraction and sampling depth. We did however find statistically significant effects of warming in all density fractions from 0-10 cm depth, 10-20 cm depth or both. Our results also including significant changes in the supposedly more stable mineral associated organic matter fraction where δ 13C values decreased at both sampling depths and the relative proportion of N-bearing compounds decreased at a sampling depth of 10-20 cm. All the observed changes can be attributed to an interplay of enhanced microbial decomposition of SOM and increased root litter input. This study suggests that soil warming destabilizes all density fractions of

  19. Conserving Soil.

    ERIC Educational Resources Information Center

    Soil Conservation Service (USDA), Washington, DC.

    Designed as enrichment materials for grades six through nine, this program is an interdisciplinary study of soils. As part of the program students: (1) examine soil organisms; (2) research history of local Native Americans to see how they and others have used the land and its soils; (3) investigate how soils are degraded and how they are conserved…

  20. Exploring 21cm-Lyman Alpha Emitter Synergies for SKA

    NASA Astrophysics Data System (ADS)

    Hutter, Anne; Dayal, Pratika; Müller, Volker; Trott, Cathryn M.

    2017-02-01

    We study the signatures of reionization and ionizing properties of early galaxies in the cross-correlations between the 21 cm emission from the spin-flip transition of neutral hydrogen (H i) and the underlying galaxy population. In particular, we focus on a sub-population of galaxies visible as Lyα Emitters (LAEs). With both observables simultaneously derived from a z≃ 6.6 hydrodynamical simulation (GADGET-2) snapshot post-processed with a radiative transfer code (pCRASH) and a dust model, we perform a parameter study and aim to constrain both the average intergalactic medium (IGM) ionization state (1-< {χ }{{H}{{I}}}> ) and the reionization topology (outside-in versus inside-out). We find that, in our model, LAEs occupy the densest and most-ionized regions resulting in a very strong anti-correlation between the LAEs and the 21 cm emission. A 1000 hr Square Kilometer Array (SKA)-LOW1—Subaru Hyper Suprime-Cam experiment can provide constraints on < {χ }{{H}{{I}}}> , allowing us to distinguish between IGM ionization levels of 50%, 25%, 10%, and fully ionized at scales r≲ 10 comoving Mpc (assuming foreground avoidance for SKA). Our results support the inside-out reionization scenario where the densest knots (under-dense voids) are ionized first (last) for < {χ }{{H}{{I}}}> ≳ 0.1. Further, 1000 hr SKA-LOW1 observations should be able to confirm the inside-out scenario by detecting a lower 21 cm brightness temperature (by about 2–10 mK) in the densest regions (≳2 arcmin scales) hosting LAEs, compared to lower-density regions devoid of them.

  1. Effects of composite soil with feldspathic sandstone and sand on soil aggregates and organic carbon

    NASA Astrophysics Data System (ADS)

    Li, J.; Han, J. C.; Zhang, Y.; Lei, G. Y.; Wang, H. Y.; Zhu, D. W.

    2016-08-01

    The case was to study the effects of soils with different proportions of feldspathic sandstone and sand on soil stability and organic carbon at 0-30 cm soil depth with four different ratios(C1, C2, C3 and C4), They were used to prepare the composite soil in Fu Ping, Shaanxi Province of China, then the soil aggregates distribution, WASR, MWD, GMD, D valueand and organic carbon content were measured and analysed.The results showed : the soil stability of C1, C2 and C3 was better than C4, i.e., the composition could improve the soil stability. With the increasing of the planting years, the contents of soil aggregates with the size >0.25 mm and MWD, GMD and SOC increased for each treatment at 0- 30 cm soil depth, which was contrary to D values. WASR of C2 was significantly higher than others (p<0.05) after 3-year planting. The significant logarithmic relationships were found between the D values and the ratios in C1, C2 and C3. Besides C1 and C2 could increase the stability and content of large soil aggregates to improve soil structure; C2 could significantly increase the SOC than others at 0- 30 cm soil depth.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Atlas of Absorption Lines from 0 to 17900 cm-1

    DTIC Science & Technology

    1987-09-01

    u—, J i i , j : 1 .’ lllll:! 1 ;, U h’,1 i L’lllll 111 ’ lilll lillh i 50 51 52 53 WAV t NUMBER 55 : ( 57...jiilli III 111 III, llll II III N,0 ’ NH, l-ICN C2H2 cm 700 55 14.2857 14.1844 140845 13.9860 13.8889 � 13.6986 13.6054 13.5135...1 1 1 1 2 3 - 4 - 5 - 6 /UITI CO CH4 OH HF H CO SUN 4250 4255 4260 4265 WAVENUMBER 4270 4275 4280 4285 4290 4295 4300 129 2 3256

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Atomic Mass and Nuclear Binding Energy for Cm-242 (Curium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Cm-242 (Curium, atomic number Z = 96, mass number A = 242).

  15. 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.

  16. 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.

  17. 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.

  18. Preconditioning with a decoupled rowwise ordering on the CM-5

    SciTech Connect

    Toledo, S.

    1995-12-01

    Decoupled rowwise ordering is an ordering scheme for 2-dimensional grids, which is tailored for preconditioning 5-point difference equations arising from discretizations of partial differential equations. This paper describes the ordering scheme and implementations of a conjugate gradient solver and SSOR preconditioners which use the decoupled rowwise and the red black ordering schemes on the CM-5 parallel supercomputer. The rowwise decoupled preconditioner leads to faster convergence than the red black preconditioner, and it reduces the solution time by a factor of 1.5 to 2.5 over a nonpreconditioned solver on a variety of test problems.

  19. 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.

  20. 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.

  1. 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.

  2. Novel treatment of an 11-cm saphenous vein graft aneurysm.

    PubMed

    Harrison, Joshua W; Swartz, Michael F; Fink, Gregory W

    2009-04-01

    Saphenous vein graft pseudoaneurysms are rare and potentially fatal complications after coronary artery bypass graft surgery. Here we present an 11-cm saphenous vein graft pseudoaneurysm from a 20-year-old vein graft to the obtuse marginal artery. The pseudoaneurysm was directly located beneath the sternum and adjacent to two patent grafts. Therefore, we used a novel approach to access the aorta through a right thoracotomy, and using a pericardial patch, we closed the ostia to the pseudoaneurysm. Postoperatively there was no longer flow into the aneurysm, and at 1-year follow-up the patient is doing well.

  3. 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.

  4. Bacterial community structure and soil properties of a subarctic tundra soil in Council, Alaska.

    PubMed

    Kim, Hye Min; Jung, Ji Young; Yergeau, Etienne; Hwang, Chung Yeon; Hinzman, Larry; Nam, Sungjin; Hong, Soon Gyu; Kim, Ok-Sun; Chun, Jongsik; Lee, Yoo Kyung

    2014-08-01

    The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is essential for predicting the response of the subarctic soil environment to climate change. To determine the composition of the bacterial community and its relationship with soil properties, we investigated the bacterial community structure and properties of surface soil from the moist acidic tussock tundra in Council, Alaska. We collected 70 soil samples with 25-m intervals between sampling points from 0-10 cm to 10-20 cm depths. The bacterial community was analyzed by pyrosequencing of 16S rRNA genes, and the following soil properties were analyzed: soil moisture content (MC), pH, total carbon (TC), total nitrogen (TN), and inorganic nitrogen (NH4+ and NO3-). The community compositions of the two different depths showed that Alphaproteobacteria decreased with soil depth. Among the soil properties measured, soil pH was the most significant factor correlating with bacterial community in both upper and lower-layer soils. Bacterial community similarity based on jackknifed unweighted unifrac distance showed greater similarity across horizontal layers than through the vertical depth. This study showed that soil depth and pH were the most important soil properties determining bacterial community structure of the subarctic tundra soil in Council, Alaska.

  5. Effects of pumice mining on soil quality

    NASA Astrophysics Data System (ADS)

    Cruz-Ruíz, A.; Cruz-Ruíz, E.; Vaca, R.; Del Aguila, P.; Lugo, J.

    2016-01-01

    Mexico is the world's fourth most important maize producer; hence, there is a need to maintain soil quality for sustainable production in the upcoming years. Pumice mining is a superficial operation that modifies large areas in central Mexico. The main aim was to assess the present state of agricultural soils differing in elapsed time since pumice mining (0-15 years) in a representative area of the Calimaya region in the State of Mexico. The study sites in 0, 1, 4, 10, and 15 year old reclaimed soils were compared with an adjacent undisturbed site. Our results indicate that gravimetric moisture content, water hold capacity, bulk density, available phosphorus, total nitrogen, soil organic carbon, microbial biomass carbon and phosphatase and urease activity were greatly impacted by disturbance. A general trend of recovery towards the undisturbed condition with reclamation age was found after disturbance, the recovery of soil total N being faster than soil organic C. The soil quality indicators were selected using principal component analysis (PCA), correlations and multiple linear regressions. The first three components gathered explain 76.4 % of the total variability. The obtained results revealed that the most appropriate indicators to diagnose the quality of the soils were urease, available phosphorus and bulk density and minor total nitrogen. According to linear score analysis and the additive index, the soils showed a recuperation starting from 4 years of pumice extraction.

  6. 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.

  7. Litter production, soil organic matter dynamics and microbial activity in two coeval forest stands on Mount Vesuvius

    NASA Astrophysics Data System (ADS)

    de Marco, Anna; Esposito, Fabrizio; Giordano, Maria; Vittozzi, Paola; Virzo de Santo, Amalia

    2010-05-01

    Forest ecosystems in different climatic zones may accumulate different amounts of soil organic matter (SOM) with different chemical-physical properties. C inputs to SOM are related to net primary production, however C accumulation in the soil largely depends on the balance between net primary production and decomposition. On the other side rates of SOM decomposition are the major control over the supply of mineral nutrients to vegetation and thus over primary production. This study was performed in two coeval (36 years old), adjacent forest stands, a Corsican pine (Pinus nigra Arn.) and a Black locust (Robinia pseudoacacia L.) forest (Atrio del Cavallo, 40° 49'N, 14° 26'E; 810 a.s.l.). The two forests were implanted in 1970 on piroclastic material of the last eruption of Mount Vesuvius (1944). We assessed the quantity and the quality of SOM in a vertical gradient in the continuum of the litter layer, humus layer and mineral soil for the whole soil profile. Moreover we estimated litter production and decomposition, litter and mineral soil (0-5cm) respiration as well as microbial biomass and total and active fungal biomass. Litter fall (measured throughout the years 2006-2008) was higher in the Corsican pine than in the Black locust stand (5234 vs. 2396 g/m2/y). Black locust leaf litter and Corsican pine needle litter reached respectively 60 % and 50% of initial mass after 600 days in situ decomposition. Consistently with the lower litter input and the higher decomposition of black locust, the amount of organic C in the organic soil layers (litter + humus), was significantly higher in the Corsican pine as compared to the Black locust stand (2702 vs. 1636 g/m2). In contrast, in the mineral layers (0-15 cm) the amount of soil organic C was slightly higher in Black locust than in Corsican pine stand (136 vs. 116 g/m2). Litter quality, decomposition dynamics, and SOM quality and activity may help to understand the reason for the uneven distribution of organic carbon

  8. Early Soil Moisture Field Experiments

    NASA Astrophysics Data System (ADS)

    Schmugge, T.

    2008-12-01

    Before the large scale field experiments described in the call for papers, there were a number of experiments devoted to a single parameter, e.g. soil moisture. In the early 1970's, before the launch of the first microwave radiometer by NASA, there were a number of aircraft experiments to determine utility of these sensors for land observations. For soil moisture, these experiments were conducted in southwestern United States over irrigated agricultural areas which could provide a wide range of moisture conditions on a given day. The radiometers covered the wavelength range from 0.8 to 21 cm. These experiments demonstrated that it is possible to observe soil moisture variations remotely using a microwave radiometer with a sensitivity of about 3 K / unit of soil moisture. The results also showed that the longer wavelengths were better, with a radiometer at the 21 cm wavelength giving the best results. These positive results led to the development of Push Broom Microwave Radiometer (PBMR) and the Electrically Scanned Thinned Array Radiometer (ESTAR) instruments at the 21-cm wavelength. They have been used extensively in the large-scale experiments such as HAPEX-MOBILHY, FIFE, Monsoon90, SMEX, etc. The multi-beam nature of these instruments makes it possible to obtain more extensive coverage and thus to map spatial variations of surface soil moisture. Examples of the early results along with the more recent soil moisture maps will be presented.

  9. The radiation shielding potential of CI and CM chondrites

    NASA Astrophysics Data System (ADS)

    Pohl, Leos; Britt, Daniel T.

    2017-03-01

    Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) pose a serious limit on the duration of deep space human missions. A shield composed of a bulk mass of material in which the incident particles deposit their energy is the simplest way to attenuate the radiation. The cost of bringing the sufficient mass from the Earth's surface is prohibitive. The shielding properties of asteroidal material, which is readily available in space, are investigated. Solution of Bethe's equation is implemented for incident protons and the application in composite materials and the significance of various correction terms are discussed; the density correction is implemented. The solution is benchmarked and shows good agreement with the results in literature which implement more correction terms within the energy ranges considered. The shielding properties of CI and CM asteroidal taxonomy groups and major asteroidal minerals are presented in terms of stopping force. The results show that CI and CM chondrites have better stopping properties than Aluminium. Beneficiation is discussed and is shown to have a significant effect on the stopping power.

  10. Tank testing of a 2500-cm2 solar panel

    NASA Technical Reports Server (NTRS)

    Bever, R. S.; Staskus, J.

    1981-01-01

    A 50 cm by 50 cm solar array panel test patch was investigated for spacecraft charging and arcing effects. Bombardment with monochromatic electron was carried out. Some objectives of the test were: (1) to estimate at what voltage of electron bombardment arcing would be probable; (2) to find whether the arc's energy would be tolerable or damagingly large; (3) to try and separate thermal and photoeffects; and, (4) to see whether materials used were such as to minimize arcing. Some conclusions were: In sunlight the tracking data relay satellite's solar panel which has ceria glass on the front and conductive paint on the backside is probably a good design for reducing charge-up. In a geomagnetic substorm simulated in testing there will be arcing at the interconnects during eclipse and transitions into and out of eclipse in testing especially in view of the very cold temperatures that will be reached by this lightweight array. Ceria-doped glass is preferred to fused silica glass for reducing charge build up. The Kapton bare patch should still be conductively painted. The differential voltages on the panel determine when arcing first begins, and the electron beam voltages vary depending upon whether the metallic structure is directly grounded or semifloating.

  11. 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.

  12. 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.

  13. Tank testing of a 2500-cm2 solar panel

    SciTech Connect

    Bever, R.S.; Staskus, J.

    1981-10-01

    A 50 cm by 50 cm solar array panel test patch was investigated for spacecraft charging and arcing effects. Bombardment with monochromatic electron was carried out. Some objectives of the test were: (1) to estimate at what voltage of electron bombardment arcing would be probable (2) to find whether the arc's energy would be tolerable or damagingly large (3) to try and separate thermal and photoeffects and, (4) to see whether materials used were such as to minimize arcing. Some conclusions were: In sunlight the tracking data relay satellite's solar panel which has ceria glass on the front and conductive paint on the backside is probably a good design for reducing charge-up. In a geomagnetic substorm simulated in testing there will be arcing at the interconnects during eclipse and transitions into and out of eclipse in testing especially in view of the very cold temperatures that will be reached by this lightweight array. Ceria-doped glass is preferred to fused silica glass for reducing charge build up. The Kapton bare patch should still be conductively painted. The differential voltages on the panel determine when arcing first begins, and the electron beam voltages vary depending upon whether the metallic structure is directly grounded or semifloating.

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Effects of tillage on the Fe oxides activation in soil

    NASA Astrophysics Data System (ADS)

    Chi, Guangyu; Chen, Xin; Shi, Yi; Wang, Jun; Zheng, Taihui

    2009-07-01

    Since mid-1950s, the wetland ecosystems in Sanjiang Plain of Northeast China have been experiencing greater changes in land use, which had negative effects on the soil environments. This study assessed the effects of soil tillage on the activation of soil Fe in the region. The test ecosystems included natural wetland, paddy field and upland field converted from wetland. Soil samples at the depths of 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, 40-60 cm, 60-90 cm and 90-120 cm were collected from each of the ecosystems for the analysis of vertical distribution of soil pH, organic carbon, chelate Fe oxides and Fe(II). The results showed that the conversion of wetland into paddy field and upland field induced a decrease of organic carbon content in 0-10 cm soil layer by 61.8% (P <0.05) and 70.0% (P < 0.05), respectively. The correlations among iron forms and soil organic carbon showed that chelate Fe oxides and Fe(II) was correlated positively with soil organic carbon and chelate ratio had a more positive relationship with organic carbon than chelate Fe oxides and Fe(II). The results of chelate Fe oxides, Fe(II) and chelate ratio of Fe suggested that reclamation could prevent the Fe activation and organic matter is credited for having an important influence on the process of Fe activation.

  1. [Effects of soil surface mulching on solar greenhouse grafted and own-rooted cucumber growth and soil environment].

    PubMed

    Zhai, Sheng; Liang, Yinli; Wang, Juyuan

    2005-12-01

    The study on the effects of different soil surface mulching models, including wheat straw mulching (WS), plastic film mulching (PF), and wheat straw plus plastic film mulching (WP), on the growth of solar greenhouse grafted and own-rooted cucumber and on soil environment showed that soil surface mulching not only increased the individuals of pistillate flower, improved its differentiation and development, shortened fruit-developing period, increased fruit weight, reduced fruit malformation percentage, but also raised total yield. Among the test mulching models, WP was better than WS and PF, and the effects were superior on grafted than on own-rooted cucumber. Soil surface mulching also had considerable effects on soil environment, but the effects varied with different modules. For example, under field condition, the diurnal change of soil temperature was a single-peak curve, with its peak higher and appeared at 14:30 in 5 cm and 10 cm soil depth, but lower and appeared later in deeper soil layers. In this study, WS lowered the maximum soil temperature and raised the minimum soil temperature, making soil temperature quite stable, while PF raised the maximum soil temperature much higher and enhanced the minimum soil temperature less than WS and WP, making the largest variation range of soil temperature. WP played a role of raising soil temperature and kept it stable. Similar to the diurnal change of soil temperature at 5 cm and 10 cm depth, that of soil respiration rate was also a single-peak curve. The soil respiration rate in all treatmentg was significantly higher than that of CK, and WP had a higher soil respiration rate than PF and WS. There was a significant positive correlation between soil respiration rate and soil temperature at 5 cm and 10 cm depth. By the end of the experiment, soil bulk density at the depth of 0-20 cm was measured, which was significantly lower in WS and WP than in CK and PF. The difference in soil bulk density was gradually inconspicuous

  2. Hg contents in soils and olive-tree (Olea Europea, L.) leaves from an area affected by elemental mercury pollution (Jódar, SE Spain).

    NASA Astrophysics Data System (ADS)

    López-Berdonces, Miguel Angel; María Esbrí, José; Amorós, José Angel; Lorenzo, Saturnino; Fernández-Calderón, Sergio; Higueras, Pablo; Perez-de-los-Reyes, Caridad

    2014-05-01

    Data from soil and olive tree leaves around a decommissioned chlor-alkali plant are presented in this communication. The factory was active in the period 1977-1991, producing duri