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Sample records for 0-15 cm soil

  1. 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...

  2. Biocrusts serve as biomarkers for the upper 30 cm soil water content

    NASA Astrophysics Data System (ADS)

    Kidron, Giora J.; Benenson, Itzhak

    2014-02-01

    Knowledge regarding the spatial distribution of moisture in soil is of great importance especially in arid regions where water is scarce. Following a previous research that showed a significant relationship between daylight surface wetness duration and the average chlorophyll content of 5 biocrusts in the Negev Desert (Israel), and the resultant outcome that pointed to the possible use of biocrusts as biomarkers for surface wetness duration, we hypothesize that biocrusts may also serve as biomarkers for the moisture content of the upper soil layer. Toward this end, daylight surface wetness duration was measured at 5 crust types following rain events during 1993-1995 along with periodical soil sampling of the upper 30 cm (at 5 cm intervals) of the soil profiles underlying these biocrusts. The findings showed a positive linear relationship between daylight surface wetness duration and the chlorophyll content of the crusts (r2 = 0.96-0.97). High correlations were also found between daylight surface wetness duration and the available water content (r2 = 0.96) and duration (r2 = 0.85-0.88) of the upper 30 cm soil and between the chlorophyll content of the crust and the available water content (r2 = 0.93-0.96) and duration (r2 = 0.78-0.84). Topography-induced shading and slope position (which determined additional water either by runoff or subsurface flow) are seen responsible for the clear link between subsurface moisture content, daylight surface wetness duration and chlorophyll content of the crust. This link points to the possible use of biocrusts as biomarkers for subsurface water content and highlights the importance of crust typology and mapping for the study of the spatial distribution of water and their potential use for the study of ecosystem structure and function.

  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. Effects of modified soil water-heat physics on RegCM4 simulations of climate over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Xuejia; Pang, Guojin; Yang, Meixue; Wan, Guoning

    2016-06-01

    To optimize the description of land surface processes and improve climate simulations over the Tibetan Plateau (TP), a modified soil water-heat parameterization scheme (SWHPS) is implemented into the Community Land Model 3.5 (CLM3.5), which is coupled to the regional climate model 4 (RegCM4). This scheme includes Johansen's soil thermal conductivity scheme together with Niu's groundwater module. Two groups of climate simulations are then performed using the original RegCM4 and revised RegCM4 to analyze the effects of the revised SWHPS on regional climate simulations. The effect of the revised RegCM4 on simulated air temperature is relatively small (with mean biases changing by less than 0.1°C over the TP). There are overall improvements in the simulation of winter and summer air temperature but increased errors in the eastern TP. It has a significant effect on simulated precipitation. There is also a clear improvement in simulated annual and winter precipitation, particularly over the northern TP, including the Qilian Mountains and the source region of the Yellow River. There are, however, increased errors in precipitation simulation in parts of the southern TP. The precipitation difference between the two models is caused mainly by their convective precipitation difference, particularly in summer. Overall, the implementation of the new SWHPS into the RegCM4 has a significant effect not only on land surface variables but also on the overlying atmosphere through various physical interactions.

  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. Assessing potential of vertical average soil moisture (0-40cm) estimation for drought monitoring using MODIS data: a case study

    NASA Astrophysics Data System (ADS)

    Ma, Jianwei; Huang, Shifeng; Li, Jiren; Li, Xiaotao; Song, Xiaoning; Leng, Pei; Sun, Yayong

    2015-12-01

    Soil moisture is an important parameter in the research of hydrology, agriculture, and meteorology. The present study is designed to produce a near real time soil moisture estimation algorithm by linking optical/IR measurements to ground measured soil moisture, and then used to monitoring region drought. It has been found that the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) are related to surface soil moisture. Therefore, a relationship between ground measurement soil moisture and NDVI and LST can be developed. Six days' NDVI and LST data calculated from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) of Shandong province during October in 2009 to May in 2010 were combined with ground measured volumetric soil moisture in different depth (10cm, 20cm, 40cm, and mean in vertical (0-40cm)) and different soil type to determine regression relationships at a 1 km scale. Based on the regression relationships, mean volumetric soil moisture in vertical (0-40cm) at 1 km resolution can be calculated over the Shandong province, and then drought maps were obtained. The result shows that significantly relationship exists between the NDVI and LST and soil moisture at different soil depths, and regression relationships are soil type dependent. What is more, the drought monitoring results agree well with actual situation.

  7. 28 CFR 0.15 - Deputy Attorney General.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Register citations affecting § 0.15, see the List of CFR Sections Affected, which appears in the Finding..., or political opinion. (2) Review cases decided by the Board of Immigration Appeals pursuant to 8 CFR... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Deputy Attorney General. 0.15 Section...

  8. 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...

  9. 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).

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  12. 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...

  13. Experimental observation on a temperature-induced decoupling between the surface states in topological insulator nanoplates Bi2-0.15(TeSe)3+0.15

    NASA Astrophysics Data System (ADS)

    Lu, Haoran; Zhang, Kang; Pan, Haiyang; Zeng, Junwen; Chen, Taishi; Song, Fengqi; Wang, Xuefeng; Miao, Feng; Zhang, Rong

    2016-04-01

    We report on the temperature-induced quantum decoupling between the surface states, demonstrated by weak antilocalization measurements, in the topological insulator Bi2-0.15(TeSe)3+0.15 nanoplates. The samples are prepared by a catalyst-free vapor-solid process with the dimension of 10 μm and the thickness of 20 nm. The channel indicator is extracted from the weak antilocalization, which presents a transition from 0.5 to 1 with the increasing temperature. This reveals the coherent decoupling between the two surface states, during which the dephasing length reaches the plate thickness. A bulk-mediated intersurface coupling model interprets the transition.

  14. 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

  15. A CM chondrite cluster and CM streams

    NASA Technical Reports Server (NTRS)

    Dodd, R. T.; Lipschutz, M. E.

    1993-01-01

    An elongate year-day concentration of CM meteoroid falls between 1921 and 1969 is inconsistent with a random flux of CM meteoroids and suggests that most or all such meteorites, and perhaps the Kaidun C-E chondrite breccia, resulted from streams of meteoroids in nearly circular, Earth-like orbits. To establish whether the post-1920 cluster might have arisen from random sampling, we determined the year-day distribution of 14 falls between 1879 and 1969 by treating each as the corner of a cell of specified dimensions (e.g. 30 years x 30 days) and calculated how many falls occurred in that cell. We then compared the CM cell distribution with random distributions over the same range of years. The results show that for 30 x 30 and 45 x 45 cells, fewer than 5 percent of random sets match the CM distribution with respect to maximum cell content and number of one-fall cells.

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  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. Commensurate magnetic structure of CeRhIn4.85 Hg0.15

    SciTech Connect

    Bao, Wei C; Ronning, Filip; Bauer, Eric D; Thompson, Joe D; Gasparovic, Y; Lynn, J; Fisk, Z

    2008-01-01

    We show using neutron diffraction that the magnetic structure of CrRhIn{sub 4.85}Hg{sub 0.15} is characterized by a commensurate propagation vector (1,2,1/2,1/2). This is different from the magnetic structure in the parent compound CeRhIn{sub 5}, which orders with an incommensurate propagation vector (1/2,1/2,0.297). The special relation between the commensurate magnetic mode and unconventional superconductivity has been shown previously for this class of heavy fermion superconductors. This work provides further evidence for the ubiquity of this antiferromagnetic mode.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  3. 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)

  4. 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

  5. Halogens in CM Chondrites

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  6. Anomalous Hall study of magnetic topological insulator Cr0.15(Bi0.1Sb0.9)1.85Te3 microflakes

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Li, Zhaoguo; Pan, Xingchen; Wang, Xuefeng; Song, Fengqi

    2015-12-01

    We report on the anomalous Hall studies in magnetic topological insulator Cr0.15(Bi0.1Sb0.9)1.85Te3 microflakes. Using the reversible magnetic field, both the resistance and Hall measurements unveil strong ferromagnetic loops with the Curie temperature of ~13 K. The ferromagnetism is believed to be mediated by the bulk p-type carriers of 1020 cm-3. The temperature-dependent and resistance-dependent scaling behaviors of the anomalous Hall resistance are analyzed, which indicates obvious suppression due to the electron-phonon interaction.

  7. 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.

  8. PAH-concentrations and compositions in the top 2 cm of forest soils along a 120 km long transect through agricultural areas, forests and the city of Oslo, Norway.

    PubMed

    Jensen, Henning; Reimann, Clemens; Finne, Tor Erik; Ottesen, Rolf Tore; Arnoldussen, Arnold

    2007-02-01

    The top 2 cm of forest soils were collected along a 120 km long south-north transect running through Norway's largest city Oslo. Forty samples were analysed for their polycyclic aromatic hydrocarbon (PAH(16) as defined by the U.S. Environmental Protection Agency) concentrations and compositions. Local variations in the PAH values are high and the reported concentrations are in general low (maximum sumPAH16: 2.6 mg/kg). The transect shows distinct differences of sumPAH16 values from south to north. PAH concentrations are substantially lower in the less populated areas at the north end of the transect than at the urbanised and much more populated south end. Several high values occur in a forested area to the north of Oslo, used for recreation purposes. The PAH distribution patterns point towards a predominantly pyrogenic origin. Local Cambrian carbon-rich black shales can be excluded as sources for PAHs in the forest soils. PMID:16787690

  9. Soil organic carbon mining versus priming - controls of soil organic carbon stocks along a management gradient

    NASA Astrophysics Data System (ADS)

    Blanes, M. Carmen; Reinsch, Sabine; Glanville, Helen C.; Jones, Davey L.; Carreira, José A.; Pastrana, David N.; Emmett, Bridget A.

    2015-04-01

    Soil carbon (C), nitrogen (N) and phosphorous (P) are assumed to be connected stoichiometrically and C:N(:P) ratios are frequently used to interpret the soils nutrient status. However, plants are capable of initiating the supply of nutrients by releasing rhizodeposits into the soil, thereby stimulating soil organic matter decomposition mediated by the rhizosphere microbial community. To test the relative importance of the two mechanisms across a fertility gradient in the UK we carried out a laboratory experiment. Intact soil cores from two depths (0-15 cm and 85-100 cm) were incubated and C, N and P were added in all possible combinations resulting in a total of 216 soil cores. Soil respiration was measured (1 h incubation, 10 oC) nine times over a 2 week period. Preliminary results indicate that all soils were C limited at the surface as measured as increased soil CO2 efflux. N additions increased soil respiration only marginally, whereas C+N stimulated microbial activity on the surface, and was even more pronounced in the deeper soil layer. Belowground responses to C+P were small and even smaller for N+P but similar for both soil depths. Our results indicate nutrient controls on soil organic matter turnover differ not only across a management/fertility gradient but also vertically down the soil profile.

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

    PubMed

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

    2013-02-01

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

  11. Electronic and multiferroic properties of Zn{sub 0.85}Mg{sub 0.15}O thin film

    SciTech Connect

    Devi, Vanita Joshi, B. C.; Kumar, Manish; Wadikar, A. D.; Choudhary, R. J.; Phase, D. M.

    2015-06-24

    Thin film sample of Zn{sub 0.85}Mg{sub 0.15}O was prepared on Si (100) substrate by pulsed laser deposition and its structural, electronic, magnetic and ferroelectric properties were investigated. The Zn{sub 0.85}Mg{sub 0.15}O thin film sample is found to show room temperature multiferroic properties; suitable for device fabrication.

  12. 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.

  13. Efficacy of 1,3-Dichloropropene in Soil Amended with Compost and Unamended Soil

    PubMed Central

    Riegel, C.; Nelson, S. D.; Dickson, D. W.; Allen, L. H.; Peterson, L. G.

    2001-01-01

    1,3-Dichloropropene (1,3-D) is a likely alternative soil fumigant for methyl bromide. The objective was to determine root-knot nematode, Meloidogyne incognita, survival in microplots after exposure to 1,3-D for various periods of time in soil that have previously been amended with compost. The treatments were 1,3-D applied broadcast at 112 liters/ha and untreated controls in both compost-amended and unamended soil. Soil samples were collected from each microplot at 6, 24, 48, 72, and 96 hours after fumigation at three depths (0-15, 15-30, and 30-45 cm). One week after fumigation, six tomato seedlings were transplanted into each microplot and root galling was recorded 6 weeks later. Plants grown in fumigated compost-amended soil had more galls than plants from fumigated unamended soil at P ≤ 0.1. Gall indices from roots in fumigated soil amended with compost were not different from nonfumigated controls. Based on soil bioassays, the number of galls decreased with increasing time after fumigation in both compost-amended and unamended soil at 0-to-15 and 15-to-30 cm depths, but not at 30 to 45 cm deep. Higher soil water content due to the elevated levels of organic matter in the soil at these depths may have interfered with 1,3-D movement, thus reducing its efficacy. PMID:19265889

  14. 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.

  15. 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

  16. Optical determination of the superconducting energy gap in electron-doped Pr1.85Ce0.15CuO4

    NASA Astrophysics Data System (ADS)

    Homes, C. C.; Lobo, R. P. S. M.; Fournier, P.; Zimmers, A.; Greene, R. L.

    2006-12-01

    The optical properties of single crystal Pr1.85Ce0.15CuO4 have been measured over a wide frequency range above and below the critical temperature (Tc≃20K) . In the normal state the coherent part of the conductivity is described by the Drude model, from which the scattering rate just above Tc is determined to be 1/τ≃80cm-1 . The condition that ℏ/τ≈2kBT near Tc appears to be a general result in many of the cuprate superconductors. Below Tc the formation of a superconducting energy gap is clearly visible in the reflectance, from which the gap maximum is estimated to be Δ0≃35cm-1 (4.3meV) . The ability to observe the superconducting energy gap in the optical properties favors the nonmonotonic over the monotonic description of the d -wave gap. The penetration depth for T≪Tc is λ≃2000Å , which when taken with the estimated value for the dc conductivity just above Tc of σdc≃35×103Ω-1cm-1 places this material on the general scaling line for the cuprates defined by 1/λ2∝σdc(T≃Tc)•Tc . These results are consistent with the observation that 1/τ≈2Δ0 , which implies that the material is not in the clean limit.

  17. Phosphorus Release to Floodwater from Calcareous Surface Soils and Their Corresponding Subsurface Soils under Anaerobic Conditions.

    PubMed

    Jayarathne, P D K D; Kumaragamage, D; Indraratne, S; Flaten, D; Goltz, D

    2016-07-01

    Enhanced phosphorus (P) release from soils to overlying water under flooded, anaerobic conditions has been well documented for noncalcareous and surface soils, but little information is available for calcareous and subsurface soils. We compared the magnitude of P released from 12 calcareous surface soils and corresponding subsurface soils to overlying water under flooded, anaerobic conditions and examined the reasons for the differences. Surface (0-15 cm) and subsurface (15-30 cm) soils were packed into vessels and flooded for 8 wk. Soil redox potential and concentrations of dissolved reactive phosphorus (DRP) and total dissolved Ca, Mg, Fe, and Mn in floodwater and pore water were measured weekly. Soil test P was significantly smaller in subsurface soils than in corresponding surface soils; thus, the P release to floodwater from subsurface soils was significantly less than from corresponding surface soils. Under anaerobic conditions, floodwater DRP concentration significantly increased in >80% of calcareous surface soils and in about 40% of subsurface soils. The increase in floodwater DRP concentration was 2- to 17-fold in surface soils but only 4- to 7-fold in subsurface soils. With time of flooding, molar ratios of Ca/P and Mg/P in floodwater increased, whereas Fe/P and Mn/P decreased, suggesting that resorption and/or reprecipitation of P took place involving Fe and Mn. Results indicate that P release to floodwater under anaerobic conditions was enhanced in most calcareous soils. Surface and subsurface calcareous soils in general behaved similarly in releasing P under flooded, anaerobic conditions, with concentrations released mainly governed by initial soil P concentrations. PMID:27380087

  18. 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.

  19. Changes to Stream Water and Soil Temperature Regimes Pre and Post Forest Harvesting in Low Order Boreal Forest Watersheds.

    NASA Astrophysics Data System (ADS)

    Allan, C. J.; Najaf, P.; Mackereth, R.; Steedman, R.

    2014-12-01

    Soil and stream water temperatures were logged at 15 minute intervals (1995-2008) pre and post logging at four intensively monitored zero order boreal forest watersheds in NW Ontario, Canada. Trends in post logging changes to daily average, maximum and diurnal ranges in stream water and soil temperatures are presented. Changes to the soil temperature regime were found to be spatially variable and dependent upon aspect, hill slope position and soil moisture regime. In general, soil temperature displayed a hysteretic behavior in relation to reference sites during the post logging period with significantly warmer spring and summer temperatures and similar autumn temperatures. Stream water temperature appeared to be controlled by post logging surface soil temperatures (0-15 cm) as opposed to deeper (30-40 cm) soil temperatures during the pretreatment period. Results are compared to previous studies and implications for soil microbial processes and stream benthic communities are highlighted.

  20. 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.

  1. 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.

  2. 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.

  3. [Surrounding characteristics of preferential flow in cultivated typical black soils of northeast China].

    PubMed

    Jiang, Xiao-jin; Wang, En-heng; Chen, Xiang-wei; Xia, Xiang-you; Shi, Chang-ting

    2010-12-01

    Taking the cultivated soils in typical black soil region of Northeast China as test objects, and by using dye tracer and double-ring infiltrometer techniques and photograph interpretation method, this paper measured and analyzed the dye-stained width and dye-stained coverage of soil transverse and longitudinal sections as well as the field maximum dye-stained depth, aimed to approach the water flow movement pattern and distribution characteristics in test soils. At soil depth 0-15 cm, matrix flow was the main soil water flow movement pattern; at depth 15-20 cm, lateral flow was observed, and the average dye-stained width and dye-stained coverage reached their maximum, being 23 cm and 20.73%, respectively. At depth 20-67 cm, the main soil water flow movement pattern was macro-pore flow, with cracks and macro-pores as the main preferential routes. The cracks at depth 20-35 cm made the preferential flow have distinct surrounding characteristics, and the macro-pores at depth 40-67 cm were the main preferential routes. Due to the existence of the preferential routes of cracks and macro-pores, the migration velocity of water in soil increased by 4.5 times, which could not only cause water loss, but also accelerate the migration of pesticides to ground water. It was suggested that these preferential routes should be decreased or eliminated during the cultivation and management on cultivated typical black soils. PMID:21442999

  4. [Surrounding characteristics of preferential flow in cultivated typical black soils of northeast China].

    PubMed

    Jiang, Xiao-jin; Wang, En-heng; Chen, Xiang-wei; Xia, Xiang-you; Shi, Chang-ting

    2010-12-01

    Taking the cultivated soils in typical black soil region of Northeast China as test objects, and by using dye tracer and double-ring infiltrometer techniques and photograph interpretation method, this paper measured and analyzed the dye-stained width and dye-stained coverage of soil transverse and longitudinal sections as well as the field maximum dye-stained depth, aimed to approach the water flow movement pattern and distribution characteristics in test soils. At soil depth 0-15 cm, matrix flow was the main soil water flow movement pattern; at depth 15-20 cm, lateral flow was observed, and the average dye-stained width and dye-stained coverage reached their maximum, being 23 cm and 20.73%, respectively. At depth 20-67 cm, the main soil water flow movement pattern was macro-pore flow, with cracks and macro-pores as the main preferential routes. The cracks at depth 20-35 cm made the preferential flow have distinct surrounding characteristics, and the macro-pores at depth 40-67 cm were the main preferential routes. Due to the existence of the preferential routes of cracks and macro-pores, the migration velocity of water in soil increased by 4.5 times, which could not only cause water loss, but also accelerate the migration of pesticides to ground water. It was suggested that these preferential routes should be decreased or eliminated during the cultivation and management on cultivated typical black soils.

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

    PubMed

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

    2016-08-01

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

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

    PubMed

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

    2016-08-01

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

  7. 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.

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  11. Carbon Sequestration in Reclaimed Mined Soils of Ohio

    SciTech Connect

    K. Lorenz; M.K. Shukla; R. Lal

    2006-04-01

    This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed mine soils (RMS). The experimental sites were characterized by distinct age chronosequences of reclaimed mine soil and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites are owned and maintained by American Electrical Power. These sites were reclaimed (1) with topsoil application, and (2) without topsoil application, and were under continuous grass or forest cover. This report presents the results from two forest sites reclaimed with topsoil application and reclaimed in 1994 (R94-F) and in 1973 (R73-F), and two forest sites without topsoil application and reclaimed in 1969 (R69-F) and 1962 (R62-F). Results from one site under grass without topsoil application and reclaimed in 1962 (R62-G) are also shown. Three core soil samples were collected from each of the experimental sites and each landscape position (upper, middle and lower) for 0-15 and 15-30 cm depths, and saturated hydraulic conductivity (Ks), volumes of transport (VTP) pores, and available water capacity (AWC) were determined. No significant differences were observed in VTP and AWC in 0-15 cm and 15-30 cm depths among the sites R94-F and R73-F reclaimed with topsoil application and under continuous forest cover (P<0.05). VTP and AWC did also not differ among upper, middle and lower landscape positions. However, saturated hydraulic conductivity in 0-15 cm depth at R73-F was significantly lower at the lower compared to the upper landscape position. No significant differences were observed for Ks among landscape positions at R94-F. No significant differences were observed in VTP and AWC among landscape positions and depths within R69-F, R62-F and R62-G. However, saturated hydraulic conductivity was higher in 0-15 cm depth at R62-F than at R69-F and R62-G. At the latter site, Ks was higher in the upper compared to the lower landscape position whereas Ks did not

  12. 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.

  13. 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. PMID:26408119

  14. 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.

  15. 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.

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

    PubMed

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

    2016-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    DOE PAGES

    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-terminalmore » off-state drain current was adequately modeled with Frenkel-Poole emission.« less

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

    DOE PAGES

    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.

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

    DOE PAGES

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

    2011-07-26

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

  1. 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.

  2. Packaging of wavelength stabilized 976nm 100W 105µm 0.15 NA fiber coupled diode lasers

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaochen; Liu, Rui; Gao, Yanyan; Zhang, Tujia; He, Xiaoguang; Zhu, Jing; Zhang, Qiang; Yang, Thomas; Zhang, Cuipeng

    2016-03-01

    Fiber coupled diode lasers are widely used in many fields now especially as pumps in fiber laser systems. In many fiber laser applications, high brightness pumps are essential to achieve high brightness fiber lasers. Furthermore, 976nm wavelength absorption band is narrow with Yb3+ doped fiber lasers which is more challenging for controlling wavelength stabilized in diode laser modules. This study designed and implemented commercial available high brightness and narrow wavelength width lasers to be able to use in previous mentioned applications. Base on multiple single emitters using spatial and polarization beam combining as well as fiber coupling techniques, we report a wavelength stabilized, 105μm NA 0.15 fiber coupled diode laser package with 100W of optical output power at 976 nm, which are 14 emitters inside each multiple single emitter module. The emitting aperture of the combined lasers output are designed and optimized for coupling light into a 105μm core NA 0.15 fiber. Volume Bragg grating technology has been used to improve spectral characteristics of high-power diode lasers. Mechanical modular design and thermal simulation are carried out to optimize the package. The spectral width is roughly 0.5 nm (FWHM) and the wavelength shift per °C < 0.02nm. The output spectrum is narrowed and wavelength is stabilized using Volume Bragg gratings (VBGs). The high brightness package has an electrical to optical efficiency better than 45% and power enclosure more than 90% within NA 0.12. Qualification tests have been included on this kind of package. Mechanical shock, vibration and accelerated aging tests show that the package is reliability and the MTTF is calculated to be more than 100k hours at 25°C.

  3. Depth-Dependent Mineral Soil CO2 Production Processes: Sensitivity to Harvesting-Induced Changes in Soil Climate.

    PubMed

    Kellman, Lisa; Myette, Amy; Beltrami, Hugo

    2015-01-01

    Forest harvesting induces a step change in the climatic variables (temperature and moisture), that control carbon dioxide (CO2) production arising from soil organic matter decomposition within soils. Efforts to examine these vertically complex relationships in situ within soil profiles are lacking. In this study we examined how the climatic controls on CO2 production change within vertically distinct layers of the soil profile in intact and clearcut forest soils of a humid temperate forest system of Atlantic Canada. We measured mineral soil temperature (0, 5, 10, 20, 50 and 100 cm depth) and moisture (0-15 cm and 30-60 cm depth), along with CO2 surface efflux and subsurface concentrations (0, 2.5, 5, 10, 20, 35, 50, 75 and 100 cm depth) in 1 m deep soil pits at 4 sites represented by two forest-clearcut pairs over a complete annual cycle. We examined relationships between surface efflux at each site, and soil heat, moisture, and mineral soil CO2 production. Following clearcut harvesting we observed increases in temperature through depth (1-2°C annually; often in excess of 4°C in summer and spring), alongside increases in soil moisture (30%). We observed a systematic breakdown in the expected exponential relationship between CO2 production and heat with mineral soil depth, consistent with an increase in the role moisture plays in constraining CO2 production. These findings should be considered in efforts to model and characterize mineral soil organic matter decomposition in harvested forest soils. PMID:26263510

  4. 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].

  5. [Effects of conservation tillage on the composition of soil exchangeable base].

    PubMed

    Hu, Ning; Lou, Yi-Lai; Zhang, Xiao-Ke; Liang, Wen-Ju; Liang, Lei

    2010-06-01

    Taking the soil in Zhangwu County of Liaoning Province as test object, a comparative study was made to understand the composition of soil exchangeable base under traditional tillage and 6-year conservation tillage (no-tillage plus straw mulch). Comparing with traditional tillage, conservation tillage increased the total amount of exchangeable base (SEB) and the contents of exchangeable K, Ca, and Mg in top (0-15 cm) soil, suggesting its positive effect in increasing soil nutrient holding capacity and buffering ability. This effect had a close relationship with the changes of soil organic matter and clay contents, according to correlation analysis. In addition, the K/SEB and Ca/Mg ratios were higher, while the (Ca+Mg)/SEB, Ca/K, and Mg/K ratios were lower under conservation tillage than under traditional tillage, illustrating that the effects of conservation tillage on soil exchangeable base were mainly presented in the relative enrichment of soil exchangeable Ca and K, especially K. Conservation tillage increased the stratification ratio (0-5 cm/5-15 cm and 0-5 cm/15-30 cm) of soil exchangeable K, Ca, and Mg, and SEB, suggesting the increase of the vertical variability of SEB in plough layer.

  6. Soil quality and barley growth as influenced by the land application of two compost types.

    PubMed

    Courtney, R G; Mullen, G J

    2008-05-01

    Agricultural use of organic residues offers an attractive method for their safe disposal and a valuable source of organic amendments and nutrients. A field experiment was conducted to investigate the influences of 0, 25, 50 and 100 t/ha spent mushroom compost (SMC), forced aeration compost (FAC) and inorganic fertilizer on soil properties and yield of barley (Hordeum vulgare). The considered soil properties (0-15 cm), after a growing season, included pH, EC, available P, Kjeldahl N, available cations, DTPA extractable elements, soil OC content, and bulk density and grain yield was also determined. Application of organic materials increased organic status of the soil and nutrient content. The effectiveness of the two composts on improving the productivity of the soil varied. SMC produced strongest correlations between soil nutrient levels and plant yield. Neither compost raised soil copper and zinc to levels that were of concern and high application rates decreased iron content.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  8. 344 cm x 86 cm low mass vacuum window

    SciTech Connect

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

    1983-08-01

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

  9. Absolute dynamic viscosity measurements of subcooled liquid oxygen from 0.15 MPa to 1.0 MPa

    NASA Astrophysics Data System (ADS)

    Hilton, D. K.; Van Sciver, S. W.

    2008-01-01

    New absolute dynamic viscosity measurements of subcooled liquid oxygen are presented which were acquired in the pressure and temperature domains from 0.15 MPa to 1.0 MPa and from 55.20 K to 90.19 K, respectively. The measurements were acquired with an uncertainty of 1% at a 95% confidence level using a pressurized gravitational capillary (PGC) viscometer specifically designed for subcooled liquefied gases. The measurements are summarized by Arrhenius-Eyring plot parameters ( μ = Ae E/ RT), and interpreted with respect to the chemical reaction rate theory of viscosity by Eyring. The Arrhenius-Eyring plot parameters reproduce the dynamic viscosity measurements with only a 2% RMS error, which is remarkable considering just two parameters are involved, A, the factor which includes the weak pressure dependence of the dynamic viscosity, and E/ R, the barrier energy of the flow, where R is the universal gas constant. Although the Arrhenius-Eyring plot parameters do not have a discernible pressure dependence in the present work, the pressure coefficient versus temperature for the dynamic viscosity was determined from line plots of the dynamic viscosity versus pressure. The pressure coefficients suggest that the pressure dependence is very weak, yet positive, and increases with decreasing temperature. Measurements at pressures an order-of-magnitude higher are required to confirm this suggestion.

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

    NASA Astrophysics Data System (ADS)

    Krezhov, Kiril; Vladikova, Daria

    2016-07-01

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

  11. Microbial degradation of propoxur in turfgrass soil.

    PubMed

    Ou, L T; Nkedi-Kizza, P; Cisar, J L; Snyder, G H

    1992-10-01

    This study was conducted to determine the degradation rates in turfgrass soil over a 12-month period after a single field application of propoxur and to isolate microorganisms from the soil capable of degrading the insecticide. Soil samples were collected from a turfgrass experimental site near Fort Lauderdale, FL one week before the field application of propoxur, and over a 12-month period after the field application. Mineralization rates in surface (0-15 cm depth) and subsurface (15-30 cm depth) soil samples collected before the field application were low. Mineralization in surface and subsurface samples collected 1, 6 and 8 months after the field application was much higher than for corresponding samples collected before the field application. Mineralization in the subsurface samples collected 12 months after the field application had reverted back to the similar rate for the corresponding sample collected before field application. Half-life values (t1/2) for propoxur showed similar trends to the results of mineralization. After a single application of propoxur, degradation in turfgrass soil was enhanced. Such enhancement lasted less than 12 months for the subsurface, but more than 12 months for the surface. A strain of Arthrobacter sp. capable of degrading propoxur was isolated from the soil.

  12. Development and mapping of seleniferous soils in northwestern India.

    PubMed

    Dhillon, Karaj S; Dhillon, Surjit K

    2014-03-01

    Periodic surveys were undertaken to identify and characterize Se-contaminated soils in northwestern India. Total Se content varied from 0.023 to 4.91mgkg(-1) in 0-15cm surface soil and 0.64-515.0mgkg(-1) in samples of vegetation. Selenium-contaminated land occupying an area of 865ha was classified into different categories based on total Se content of soils as moderately contaminated (0.5-2.0mg Sekg(-1)) and highly contaminated (>2.0mg Sekg(-1)). The normal soils contained <0.5mg Sekg(-1). The soil map was prepared using village level cadastral maps. Se-contaminated soils were silty loam to silty clay loam in texture and tested pH 7.9-8.8, electrical conductivity 0.3-0.7dSm(-1), calcium carbonate 0.1-4.1% and organic carbon 0.4-1.0%. Selenium was present throughout the soil profile up to 2m depth; 0-15cm surface soil layer contained 1.5 to 6.0 times more Se than in subsurface layers. Selenium content in rock samples collected from lower and upper Shiwalik sub-Himalayan ranges varied from 1864 to 2754 and 11 to 847μgkg(-1), respectively. The sediments transported through seasonal rivulets linking the Shiwalik ranges to affected sites contained 0.57-2.89mg Sekg(-1). The underground water containing 2.5-69.5μg SeL(-1) used for irrigating transplanted rice grown in Se-contaminated area resulted in a net Se addition in soil up to 881gha(-1)y(-1); possibly further aggravating the Se-toxicity problem. Presence of substantial amount of Se in rock samples and sediments of seasonal rivulets suggests that Se-rich materials are being transported from Shiwalik hills and deposited in regions where seasonal rivulets end up. PMID:24210553

  13. Development and mapping of seleniferous soils in northwestern India.

    PubMed

    Dhillon, Karaj S; Dhillon, Surjit K

    2014-03-01

    Periodic surveys were undertaken to identify and characterize Se-contaminated soils in northwestern India. Total Se content varied from 0.023 to 4.91mgkg(-1) in 0-15cm surface soil and 0.64-515.0mgkg(-1) in samples of vegetation. Selenium-contaminated land occupying an area of 865ha was classified into different categories based on total Se content of soils as moderately contaminated (0.5-2.0mg Sekg(-1)) and highly contaminated (>2.0mg Sekg(-1)). The normal soils contained <0.5mg Sekg(-1). The soil map was prepared using village level cadastral maps. Se-contaminated soils were silty loam to silty clay loam in texture and tested pH 7.9-8.8, electrical conductivity 0.3-0.7dSm(-1), calcium carbonate 0.1-4.1% and organic carbon 0.4-1.0%. Selenium was present throughout the soil profile up to 2m depth; 0-15cm surface soil layer contained 1.5 to 6.0 times more Se than in subsurface layers. Selenium content in rock samples collected from lower and upper Shiwalik sub-Himalayan ranges varied from 1864 to 2754 and 11 to 847μgkg(-1), respectively. The sediments transported through seasonal rivulets linking the Shiwalik ranges to affected sites contained 0.57-2.89mg Sekg(-1). The underground water containing 2.5-69.5μg SeL(-1) used for irrigating transplanted rice grown in Se-contaminated area resulted in a net Se addition in soil up to 881gha(-1)y(-1); possibly further aggravating the Se-toxicity problem. Presence of substantial amount of Se in rock samples and sediments of seasonal rivulets suggests that Se-rich materials are being transported from Shiwalik hills and deposited in regions where seasonal rivulets end up.

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

    NASA Technical Reports Server (NTRS)

    Zuo, F.

    1995-01-01

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

  15. 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. PMID:24742554

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

    PubMed

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

    2004-09-01

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

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

    PubMed

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

    2004-09-01

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

  18. 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.

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

    SciTech Connect

    Zhai Jiwei; Shen Bo; Yao Xi; Zhang Liangying

    2004-09-01

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

  20. 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.

  1. 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

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

    DOE PAGES

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

    2015-12-08

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    SciTech Connect

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

    2009-09-15

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

  5. 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

    2015-04-01

    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.

  6. 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.

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-15

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

  9. 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.

  10. Monitoring of soil water storage along elevation transech on morphological diverse study-sites affected by soil erosion

    NASA Astrophysics Data System (ADS)

    Jaksik, Ondrej; Kodesova, Radka; Nikodem, Antonin; Fer, Miroslav; Klement, Ales; Kratina, Josef

    2015-04-01

    Soil water availability is one of the key factors determining plant growth. Spatial distribution of soil water content is influenced by many factors. For the field-scale, one of the most important factors is terrain and its shape. The goal of our study was to characterize soil water storage within the soil profile with respect to terrain attributes. Two morphologically diverse study sites were chosen, in order to monitor soil water storage during vegetation season. The first site Brumovice in located in the Southern Moravian Region. The original soil unit was Haplic Chernozem developed on loess, which was gradually degraded by soil erosion. In the steepest parts, due to substantial loss of soil material, soil is transformed to Regosol. As a result of consequently sedimentation of previously eroded material in toe slopes and terrain depressions colluvial soils are formed. The second site Vidim is placed in the Central Bohemia. Dominant soil unit in wider area is Haplic Luvisol on loess loam. Similar process of progressive soil transformation was identified. On each study site, two elevation transects were delimited, where each consists of 5 monitoring spots. Access tubes were installed in order to measure soil moisture in six different depths (10, 20, 30 40, 60 a 100 cm) using Profile Probe PR2. The monitoring was conducted during vegetation season: April - July 2012 in Brumovice and May - July 2013 in Vidim. The average soil water contents were calculated for following three layers: topsoil A (0-20 cm), subsoil B (20-40cm), and substrate (40-100cm). The soil water storage within the soil profile was also expressed. Sensors TMS3 were also used for continual soil water content monitoring in the depth of 0-15 cm. In addition undisturbed soil samples were taken from topsoil to measure soil hydraulic properties using the multistep outflow experiment. Data were used to assess retention ability of erosion affected soils. The soil water storage and particularly average

  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. 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

  13. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  14. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  15. [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.

  16. Chemical pressure effect in the heavy fermion compound Ce 1-yLa y(Ru 0.85Rh 0.15) 2Si 2

    NASA Astrophysics Data System (ADS)

    Horii, Tsuyoshi; Shimada, Satomi; Nakano, Tomohito; Murayama, Shigeyuki; Takano, Hideaki; Hedo, Masato; Uwatoko, Yoshiya

    2007-03-01

    We have measured the susceptibility and resistivity on single-crystalline Ce 1-yLa y(Ru 0.85Rh 0.15) 2Si 2 along the tetragonal c-axis. The susceptibility increases with decreasing temperature, and then rapidly decreases, indicating the AF transition in each La concentration y. The resistivity also shows an anomaly in each La concentration y at around the TN. For y⩽0.1, we observe a jump in resistivity just below TN as is seen for Ce(Ru 0.85Rh 0.15) 2Si 2. This is interpreted in terms of the gap opening on the Fermi-surface along the c-axis. However, for y⩾0.2 the resistivity shows a downward bend at TN. These experimental facts suggest that the crossover from the spin density wave (SDW) with the gap opening to the localized AF order occurs at around y=0.1.

  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. 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; Lin, Feng; Lan, Yucheng

    2015-01-01

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

  19. Pulsed laser deposition growth and transport studies of superconducting La1.85Y0.15CuO4 thin films

    NASA Astrophysics Data System (ADS)

    Yu, Weiqiang; Liang, B.; Li, P.; Greene, R. L.; Fujino, S.; Murakami, T.; Takeuchi, I.

    2007-03-01

    The recent MBE growth of the ``nominally undoped" cuprate superconductor (La,RE)2CuO4 has led to the speculation that this system is a band metal and not a ``doped Mott insulator" as found in all other superconducting cuprates ^1. Here we report the first pulsed laser deposition (PLD) growth of insulating and superconducting La1.85Y0.15CuO4 thin films, which are prepared under different oxygen conditions. We also report resistivity, Hall, Nernst, and magnetoresistance measurements, which show that La1.85Y0.15CuO4 is an electron-doped, Mott-Hubbard system, where the carriers originate from oxygen nonstoichiometry produced by the oxygen reduction. This work is supported by NSF (DMR 0352735).^1A. Tsukada et al., Sol. Stat. Commu. 133, 427 (2005).

  20. The dynamic critical exponent in optimally doped Pr1.85Ce0.15CuO4 as a function of film inhomoegneity

    NASA Astrophysics Data System (ADS)

    Isaacs, R. A.; Olson, J. B.; Sousa, J.; Salvaggio, M.; Sullivan, M. C.; Greene, R. L.

    2009-03-01

    Scaling analysis of voltage vs. current isotherms is a good tool to study the normal-superconducting phase transition in cuprate conductors. This measurement has never been performed on the optimally doped cuprate conductor Pr1.85Ce0.15CuO4. If we take the finite thickness of the films into account,ootnotetextSullivan et al., Phys. Rev B 69, 214524 (2004) we can find the critical isotherm and determine the dynamic critical exponent z in our Pr1.85Ce0.15CuO4 films. We find that the critical exponent varies as a function of transition width, from which we can infer the effect of sample inhomogeneity on the dynamic critical exponent. We present our results of the critical exponent as a function of sample inhomogeneity and compare it to the hole-doped cuprate YBa2Cu3O7-δ.

  1. c -axis longitudinal magnetoresistance of the electron-doped superconductor Pr1.85Ce0.15CuO4

    NASA Astrophysics Data System (ADS)

    Yu, W.; Liang, B.; Greene, R. L.

    2006-12-01

    We report c -axis resistivity and longitudinal magnetoresistance measurements of superconducting Pr1.85Ce0.15CuO4 single crystals. In the temperature range 13⩽T⩽32K , a negative magnetoresistance is observed at fields just above HC2 . Our studies suggest that this negative magnetoresistance is caused by superconducting fluctuations. At lower temperatures (T⩽13K) , a different magnetoresistance behavior and a resistivity upturn are observed, whose origin is still unknown.

  2. Oxygen-doped Mott-Hubbard cuprate superconductor La1.85Y0.15CuO4-δ from transport measurements

    NASA Astrophysics Data System (ADS)

    Yu, W.; Liang, B.; Li, P.; Fujino, S.; Murakami, T.; Takeuchi, I.; Greene, R. L.

    2007-01-01

    We report resistivity, Hall effect, Nernst effect, and magnetoresistance measurements on T' -phase La1.85Y0.15CuO4-δ (LYCO) films prepared by pulsed laser deposition under different oxygen conditions. Our results show that superconductivity in LYCO originates from an oxygen-doped Mott-like insulator and not from a weakly correlated, half-filled band metal as proposed previously.

  3. 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.

  4. 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. PMID:25134679

  5. Neutron powder diffraction study and magnetic properties in LaMn1-xCuxO3 (x=0.05, 0.10 and 0.15)

    NASA Astrophysics Data System (ADS)

    Samantaray, B.; Srivastava, S. K.; Mohanty, S.; Ravi, S.; Dhiman, I.; Das, A.

    2010-05-01

    LaMn1-xCuxO3 (x=0.05 to 0.15) samples were prepared and their crystal structure and magnetic properties were studied by recording neutron powder diffraction patterns and M-H loops at different temperatures. Even though the samples were free from impurity, the x=0.05 and 0.10 samples are found to crystallize in mixture of R3¯c and Pnma space group with dominate fraction of former one. The phase fraction for x=0.10 sample is found to vary with temperature especially below the ferromagnetic TC. The x=0.15 sample could be refined based on Pnma space group. The patterns at low temperatures could be refined by considering magnetic reflections corresponding to ferromagnetic structure. The magnetic moments of Mn ion are found to be along b axis with typical value of 3.40(3)μB for x=0.10 sample. From the analysis of the diffraction patterns and the magnetization data, it is found that x=0.15 sample exhibit spin canting.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

  8. 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.

  9. Carbon Sequestration in Reclaimed Mined Soils of Ohio

    SciTech Connect

    M.K. Shukla; K. Lorenz; R. Lal

    2005-10-01

    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. Among the three sites chosen for this study one was reclaimed in 1978 (Cumberland), one in 1987 (Switch Grass) and one site was reclaimed in 1994 (Tilton's Run). All three sites were reclaimed with topsoil application and were under continuous grass cover. Eighteen experimental plots were developed on each site. Five fertilization treatments were applied in triplicate on each experimental site. During this quarter, water infiltration tests were performed on the soil surface in the experimental plots. Soil samples were analyzed for soil moisture characteristics. This report presents the data on infiltration rates, volume of transport and storage pores, and available water capacity (AWC) of soil. The infiltration rates after 5 min (i{sub 5}) showed high statistical variability (CV > 0.62) among the three sites. Both steady state infiltration rate and cumulative infiltration showed moderate to high variability (CV > 0.35). The mean values for the infiltration rate after 5 min, steady state infiltration rate, and cumulative infiltration were higher for Switch Grass (2.93 {+-} 2.05 cm min{sup -1}; 0.63 {+-} 0.34 cm min{sup -1}; 113.07 {+-} 39.37 cm) than for Tilton's Run (1.76 {+-} 1.42 cm min{sup -1}; 0.40 {+-} 0.18 cm min{sup -1}; 73.68 {+-} 25.94 cm), and lowest for Cumberland (0.63 {+-} 0.34 cm min{sup -1}; 0.27 {+-} 0.19 cm min{sup -1}; 57.89 {+-} 31.00 cm). The AWC for 0-15 cm soil was highest at Tilton's Run (4.21 {+-} 1.75 cm) followed by Cumberland (3.83 {+-} 0.77 cm) and Switch Grass (3.31 {+-} 0.10 cm). In 15-30 cm depth Switch Grass had

  10. 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.

  11. 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. PMID:23455430

  12. 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.

  13. 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.

  14. Application of organic amendments to restore degraded soil: effects on soil microbial properties.

    PubMed

    Carlson, Jennifer; Saxena, Jyotisna; Basta, Nicholas; Hundal, Lakhwinder; Busalacchi, Dawn; Dick, Richard P

    2015-03-01

    Topsoil removal, compaction, and other practices in urban and industrial landscapes can degrade soil and soil ecosystem services. There is growing interest to remediate these for recreational and residential purposes, and urban waste materials offers potential to improve degraded soils. Therefore, the objective of this study was to compare the effects of urban waste products on microbial properties of a degraded industrial soil. The soil amendments were vegetative yard waste compost (VC), biosolids (BioS), and a designer mix (DM) containing BioS, biochar (BC), and drinking water treatment residual (WTR). The experiment had a completely randomized design with following treatments initiated in 2009: control soil, VC, BioS-1 (202 Mg ha(-1)), BioS-2 (403 Mg ha(-1)), and DM (202 Mg BioS ha(-1) plus BC and WTR). Soils (0-15-cm depth) were sampled in 2009, 2010, and 2011 and analyzed for enzyme activities (arylsulfatase, β-glucosaminidase, β-glucosidase, acid phosphatase, fluorescein diacetate, and urease) and soil microbial community structure using phospholipid fatty acid analysis (PLFA). In general, all organic amendments increased enzyme activities in 2009 with BioS treatments having the highest activity. However, this was followed by a decline in enzyme activities by 2011 that were still significantly higher than control. The fungal PLFA biomarkers were highest in the BioS treatments, whereas the control soil had the highest levels of the PLFA stress markers (P < 0.10). In conclusion, one-time addition of VC or BioS was most effective on enzyme activities; the BioS treatment significantly increased fungal biomass over the other treatments; addition of BioS to soils decreased microbial stress levels; and microbial measures showed no statistical differences between BioS and VC treatments after 3 years of treatment. PMID:25673270

  15. Characterization of Soil Organic Matter from African Dark Earth (AfDE) Soils

    NASA Astrophysics Data System (ADS)

    Plante, A. F.; Fujiu, M.; Ohno, T.; Solomon, D.; Lehmann, J.; Fraser, J. A.; Leach, M.; Fairhead, J.

    2014-12-01

    Anthropogenic Dark Earths are soils generated through long-term human inputs of organic and pyrogenic materials. These soils were originally discovered in the Amazon, and have since been found in Australia and in this case in Africa. While tropical soils are typically characterized by low soil organic matter (SOM) concentrations, African Dark Earths (AfDE) are black, highly fertile and carbon-rich soils formed through an extant but ancient soil management system. The objective of this study was to characterize the organic matter accumulated in AfDE and contrast it with non-AfDE soils. Characterization of bulk soil organic matter of several (n=11) AfDE and non-AfDE pairs of surface (0-15 cm) soils using thermal analysis techniques (TG-DSC-EGA) resulted in substantial differences in SOM composition and the presence of pyrogenic C. Such pyrogenic organic matter is generally considered recalcitrant, but the fertility gains in AfDE are generated by labile, more rapidly cycling pools of SOM. As a result, we characterized hot water- and pyrophosphate-extractable pools of SOM using fluorescence (EEM/PARAFAC) and high resolution mass spectrometry (FT-ICR-MS). EEM/PARAFAC data suggests that AfDE samples had a greater fraction of their DOM that was more humic-like than the paired non-AfDE samples. Similarly, FT-ICR-MS analyses of extracts suggest that differences among the sites analyzed were larger than between the paired AfDE and non-AfDE extracts. Overall, in spite of substantial differences in the composition of bulk SOM, the extractable fractions appear to be relatively similar between the AfDE and non-AfDE soils.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  17. 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

  18. 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

  19. Systematic study of (La1-xGdx)1.85Sr0.15CuO4 (0<=x<=1): Structure, superconductivity, resistivity, and magnetic properties

    NASA Astrophysics Data System (ADS)

    Xiao, Gang; Cieplak, Marta Z.; Chien, C. L.

    1989-09-01

    A room-temperature structural phase diagram has been determined in (La1-xGdx)1.85Sr0.15CuO4 system (0<=x<=1). There exist three stable phases (T, T* and T'), in which the local Cu-O unit is an octahedron, a pyramid, and a square, respectively. The Jahn-Teller distortion is reduced in the order of T, T*, and T'. For each phase, there is a solubility region. No magnetic ordering is found in the T and T* phase, both of which exhibit paramagnetism with a constant Gd magnetic moment consistent with that of Gd3+. In Gd2CuO4 and Gd1.85Sr0.15CuO4, the initial susceptibility indicates a Néel state in the Cu-O2 plane at TN=285 K and another magnetic transition at low temperature. TN is not sensitive to the Sr doping at all, indicating that extra holes cannot be doped onto the Cu-O2 plane. While the T* and T' phases are insulating, exhibiting a variable-range hopping behavior, the Gd-doped (La1-xGdx)1.85Sr0.15CuO4 (x<=0.1) is superconducting with Tc reducing with increasing Gd concentration. The suppression of Tc is not due to a variation of the electron-boson coupling strength which remains unchanged in the system, but correlates closely with the low-temperature resistivity anomaly. Such an anomaly can be best described by a logarithmic temperature dependence.

  20. 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.

  1. Tunneling behaviors of photogenerated electrons in In{sub 0.15}Ga{sub 0.85}As/GaAs quantum well photoelectrodes

    SciTech Connect

    Liu, Y.; Xiao, X.R.; Zeng, Y.P.; Pan, D.

    1999-11-25

    The photovoltaic spectral features and the behaviors of photocurrent versus the electrode potential for near surface In{sub 0.15}Ga{sub 0.85}As/GaAs quantum well electrodes have been investigated in nonaqueous solutions of ferrocene and acetylferrocene. The photovoltaic spectrum shows a sharp structure that reflects confined state-to-state exciton transition in the quantum well. Deep dips are observed in the photocurrent versus the electrode potential curves in both electrolytes at the different electrode potentials under the illumination of exciton resonance wavelength. These dips are qualitatively explained by considering the interfacial tunneling transfer of photogenerated electron within the quantum well.

  2. Critical state and low-field electrodynamics in LaO0.85F0.15FeAs superconductor polycrystals

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    The penetration of a weak magnetic field into LaO0.85F0.15FeAs 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.

  3. 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.

  4. 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.

  5. Toxicity of the antimicrobial oxytetracycline to soil organisms in a multi-species-soil system (MS.3) and influence of manure co-addition.

    PubMed

    Boleas, Sara; Alonso, Carmen; Pro, Javier; Fernández, Carlos; Carbonell, Gregoria; Tarazona, Jose V

    2005-07-15

    The effects of oxytetracycline (OTC) on soil organisms have been studied using a multi-species-soil system (MS.3). Oxytetracycline concentrations of 0.01 mg/kg, 1 mg/kg and 100 mg/kg soil were added to the 20 cm top arable soil layer, with and without horse/cow manure (0.15 g organic N/kg soil) co-addition. No mortality was observed for Eisenia foetida S. but significant effects on soil microbial enzymatic activities (phosphatase, dehydrogenase) were observed. The effects on soil microorganism were observed earlier but then recovered in systems with manure co-addition. More important, OTC related plant inhibition was observed in the manured but not in the non-manured systems. Oxytetracycline reached 0.19 and 1.85 mg/l in the leachate of the soil spiked with 1 and 100 mg OTC/kg, respectively and 0.05 and 1.14 mg/l for the same OTC concentrations in the manured systems. The results confirm that manure can modify both the fate and the effects of OTC and that the multi-species-soil systems can reproduce the conditions for a realistic effect estimation of veterinary medicines.

  6. 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...

  7. Preparation and magnetocaloric effect of (La0.67-XGdX)Sr0.33MnO3 (X =0.1,0.15) nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, G.; Wang, Z.-D.; Zhang, L.-D.

    2005-05-01

    We report a new route to synthesize nanosized (La0.67-XGdX)Sr0.33MnO3 (X=0.1,0.15) perovskite crystalline complex oxides at calcination temperatures of 600-900 °C using amorphous molecular alloy as precursor. The precursor could completely decompose into oxide at temperatures below 500 °C according to thermogravimetric analysis and differential thermal analysis results. X-ray diffraction demonstrated that the decomposed species was composed of perovskite structure at a calcination temperature of 600 °C for 2 h. The size and topography of the oxides are dependent on the calcination temperature of the precursor. The resulting particle size is in the range of 40-120 nm as determined by a transmission electron microscope. This method is effective and can be easily quantitatively controlled to synthesize nanosized perovskite complex oxides. The Curie temperature TC and the magnetocaloric effect of (La0.67-XGdX)Sr0.33MnO3 (X=0.1,0.15) nanoparticles are discussed based on the measurement of the low-field magnetization curve and the isothermal magnetization curve.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  10. Thermoelectric Properties of Cu-doped Bi2Te2.85Se0.15 Prepared by Pulse-Current Sintering Under Cyclic Uniaxial Pressure

    NASA Astrophysics Data System (ADS)

    Kitagawa, Hiroyuki; Mimura, Naoki; Takimura, Kodai; Morito, Shigekazu; Kikuchi, Kotaro

    2016-03-01

    N-type Cu-doped Bi2Te2.85Se0.15 thermoelectric materials were prepared by pulse-current sintering under cyclic uniaxial pressure, and the effect of the cyclic uniaxial pressure on texture and thermoelectric properties was investigated. Cu x Bi2Te2.85Se0.15 ( x = 0-0.03) powder prepared by mechanical alloying was sintered at 673 K using pulse-current heating under 100 MPa of cyclic uniaxial pressure. X-ray diffraction patterns and electron backscattered diffraction analyses showed that the cyclic uniaxial pressure was effective for texture control. The flattened crystal grains were stacked in the thickness direction of the sintered materials and the hexagonal c-plane strongly tended to align in the direction perpendicular to the uniaxial pressure. As a result of this crystal alignment, the electrical resistivity in the direction perpendicular to the uniaxial pressure became smaller than that of equivalent samples prepared with a constant uniaxial pressure. The smaller resistivity led to a larger power factor, and the figure of merit was improved by the application of cyclic uniaxial pressure.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  12. Terahertz and infrared studies of antiferroelectric phase transition in multiferroic Bi0.85Nd0.15FeO3

    NASA Astrophysics Data System (ADS)

    Goian, V.; Kamba, S.; Greicius, S.; Nuzhnyy, D.; Karimi, S.; Reaney, I. M.

    2011-10-01

    High-frequency dielectric studies of Bi0.85Nd0.15FeO3 ceramics performed betweeen 100 and 900 K reveal hardening of most polar phonons on cooling below antiferroelectric phase transition, which occurs near 600 K. Moreover, a strong THz dielectric relaxation is seen in paraelectric phase. Its relaxation frequency softens on cooling towards TC ≈ 600 K, its dielectric strength simultaneously decreases, and finally the relaxation disappears from the spectra below 450 K. Both phonon and dielectric relaxation behavior are responsible for a decrease in the dielectric permittivity at the antiferroelectric phase transition. Origin of unusual strong THz dielectric relaxation in paraelectric phase is discussed. Bi0.85Nd0.15FeO3 structure lies on the phase boundary between polar rhombohedral and non-polar orthorhombic phase and owing to this, the polarization rotation and polarization extension can enhance the piezoelectric response of this system. Similarities and discrepancies with lead-based piezoelectric perovskites, exhibiting morphotrophic phase boundary between two ferroelectric phases, are discussed.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  15. Calculations of the spectral nature of the microwave emission from soils. [Arizona and Georgia

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.; Choudhury, B. J. (Principal Investigator)

    1980-01-01

    The brightness temperatures for a set of soil profiles observed at USDA facilities in Arizona and Georgia were calculated at the wavelengths of 2.8, 6, 11, 21, and 49 cm using a coherent radiative transfer model. The soil moisture sampling depth is found to be a function of wavelength and is in the range 0.06 to 0.1 of a wavelength. The thermal sampling depth also depends on wavelength and is approximately equal to one wavelength at dry soil condition and 0.1 - 0.5 wavelengths at wet soil conditions. Calculated values of emissivity show strong diurnal variations when the soils are wet, while there is little diurnal change when the soil is dry. The soil moistures within the four depth intervals of 0-2, 0-5, 0-9, and 0-15 cm were parameterized as function of the calculated emissivity and brightness temperature. Best-fit parameters and correlation coefficients are presented for five wavelengths. Interrelationships among the effective temperature, surface temperature, and emissivity are displayed.

  16. 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.

  17. Heavy metal contents, distribution, and prediction in a regional soil-wheat system.

    PubMed

    Ran, Jing; Wang, Dejian; Wang, Can; Zhang, Gang; Zhang, Hailin

    2016-02-15

    The entry of heavy metals into the food chain is of concern for potential health risks. To investigate the spatial relationships of heavy metals in a regional soil-wheat system, 99 pairs of surface soil (0-15 cm) and wheat grain samples were collected from Changshu, China, a typical county in the Yangtze Delta region. Both soil and wheat grain samples were analyzed for total Cd, Cu, Ni, Pb, and Zn. DTPA-extractable metals and major physico-chemical properties were also determined for soil samples. Moderate accumulation of heavy metals was found in soils and wheat grains, especially Cd. However, the levels were within the target hazard quotients (THQ) safe values with respect to non-carcinogenic risks, but more attention should be paid to Cd. Spatially, Cd, Cu, Ni, and Zn in wheat grains and soils had similar geographical patterns, whereas Pb showed opposite trends. Cross-correlograms further quantitatively confirmed the spatial relationships of heavy metals in wheat grains and soils. In addition, heavy metals in wheat grains were significantly spatially correlated with most soil physio-chemical properties. Particularly, a set of regression models for Cd in wheat grains were established with a maximum predictive success of 65%. These models can be used to predict Cd in wheat grains, and thus allows farmers to decrease the threat by certain framing practices such as ameliorating soil pH or growing a less metal-accumulating cultivar. PMID:26657387

  18. [Spatial variability of quasidiffusion coefficients for 137Cs in grey forest soils in the distant zone of contamination from the Chernobyl NPP].

    PubMed

    Lipatov, D N; Shcheglov, A I

    2014-01-01

    The calculated values of quasidiffusion coefficients for 137Cs for the 15-year period after the Chernobyl fallout in the top mineral thickness of grey forest soils of the Tula region vary within 0.18-0.35 cm2/year, accruing among biogeocenoses: pine forest < oak forest < birch forest < pasture. Correlations are revealed and the equations of linear regression for quasidiffusion coefficients for 137Cs depending on soil properties are constructed. Estimates of the periods of effective residence half-time of 137Cs in grey forest soils are made: for a layer of 0-5 cm - 11-14 years 0-15 cm - 22-25 years, 0-30 cm - 27-28 years. The periods necessary for the decrease in the contents of 137Cs in a 0-5 cm layer of soils to the level of 37 kBq/m2 are considered, taking into account a spatial variation of fallout and heterogeneity of quasidiffusion. Forecasts of the vertical migration of 137Cs on the basis of the diffusive model with spatially distributed soil parameters are submitted.

  19. 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

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

    SciTech Connect

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

    2015-07-15

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

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

    SciTech Connect

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

    2000-01-03

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

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

    PubMed

    Longstaff, E; von Krogh, G

    2001-04-01

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

  3. 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.

  4. Local tunneling spectroscopy of the electron-doped cuprate superconductor Sm1.85Ce0.15CuO4

    NASA Astrophysics Data System (ADS)

    Zimmers, A.; Noat, Y.; Cren, T.; Sacks, W.; Roditchev, D.; Liang, B.; Greene, R. L.

    2007-10-01

    We present local tunneling spectroscopy in the optimally electron-doped cuprate Sm2-xCexCuO4 , x=0.15 . A clear signature of the superconducting gap is observed with an amplitude ranging from place to place and from sample to sample ( Δ˜3.5 6meV) . Another spectroscopic feature is simultaneously observed at high energy with an amplitude ranging from ±60 to ±80meV . Its energy scale and temperature evolution are found to be compatible with previous photoemission and optical experiments. If interpreted as the signature of antiferromagnetic order in the samples, these results could suggest the coexistence on the local scale of antiferromagnetism and superconductivity on the electron-doped side of cuprate superconductors.

  5. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Xiong, Wei

    2016-08-01

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

  8. 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.

  9. 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.

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

    SciTech Connect

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

    2013-10-15

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

  11. Study of structural, dielectric and magnetic behaviour of Ni0.75Zn0.25Fe2O4-Ba(Ti0.85Zr0.15)O3 composites

    NASA Astrophysics Data System (ADS)

    Adhlakha, Nidhi; Yadav, K. L.

    2012-11-01

    A class of hybrid composites (x)Ni0.75Zn0.25Fe2O4-(1 - x)Ba(Ti 0.85Zr 0.15)O 3 (for x variations 0, 0.20, 0.30 and 0.40) synthesized via a solid state reaction method is investigated. The structural analysis was carried out using an x-ray diffraction graph which reveals a mixed phase of the hybrid composites with spinel phase for ferrite component and perovskite phase for the ferroelectric component. The microstructural analysis and grain size determination is carried out using a field emission scanning electron microscope (FESEM). The relative dielectric constant with frequency variation (in the range of 100 Hz-1 MHz) and temperature at three fixed frequencies (100 Hz, 1 KHz and 10 KHz) is studied. The magnetic properties such as saturation magnetization (Ms ) and magnetic moment (μB) are calculated from the magnetic hysteresis loops obtained using a vibrating sample magnetometer (VSM). The value of remnant polarization for pure BZT is found to be 6.18 μC cm-2 and as the content of ferrite phase is increased up to 40 mol%, this value decreases. The magnetoelectric effect is studied using magnetocapacitance which takes a maximum value for 40 mol% addition of ferrite.

  12. Low loss, high tunable BaZr0.2Ti0.8O3/BaSn0.85Ti0.15O3 heterostructure thin films

    NASA Astrophysics Data System (ADS)

    Yu, Shihui; Zhang, Jieling; Li, Lingxia; Zheng, Haoran; Zhang, Weifeng

    2016-10-01

    Ferroelectric BaZr0.2Ti0.8O3/BaSn0.85Ti0.15O3 (BZT/BTS) heterostructure thin films (˜200-nm-thick) have been prepared on Pt/TiOx/SiO2/Si substrates by pulsed laser deposition. The heterostructure thin films are crack free, compact, and crystallized in a perovskite structure. Dielectric measurements indicate that the BZT/BTS heterostructure thin films exhibit a low dielectric loss of below 0.007, a medium dielectric constant of ˜441, and the superior tunable dielectric properties at room temperature. Calculations of tunability and figure of merit (FOM) display a maximum value of 68.5% at 500 kV/cm and ˜101, respectively. The FOM value is higher than that of the single-layer BTS and BZT thin films. A brief discussion is given on the lower loss compared to the single-layer thin films. The results indicate that BZT/BTS heterostructure thin films are excellent candidates for electrically steerable applications.

  13. Titanates de cuivre substitués à structure bixbyite: Les composés Cu 1- xTi 1- xFe 2 xO 3 (0.15 ≤ x ≤ 0.33)

    NASA Astrophysics Data System (ADS)

    Mouron, Paule; Odier, Philippe; Choisnet, Jacques

    1985-11-01

    A new bixbyite family, Cu 1- xTi 1- xFe 2 xO 3 (0.15 ≤ x ≤ 0.33) has been synthesized and characterized. The unit cell is cubic: a ˜ 9.40Å. The X-ray powder diffraction study shows up an isotypism with the (Fe, Mn) 2O 3 compounds. There is a disordered distribution of Cu II, Ti IV, and Fe III over the two cyrstallographic sites: P I and P II. P II is highly distorted (two long MO distances) by the Jahn-Teller effect of Cu II. The bixbyite structure is described in terms of polyhedra arrangement, as a particular case of the C M2O 3 family. The cation packing is discussed in relation with the existence of the bixbyite structure for the Cu 1- xTi 1- xFe 2 xO 3 compounds. The electrical properties (σ ˜ 10 -5(Ω cm) -1 for x = 0.286 at room temperature) show an electron conduction with probably a hopping mechanism.

  14. Impact of long-term land application of broiler litter on environmentally related soil properties

    SciTech Connect

    Kingery, W.L.; Wood, C.W.; Mullins, G.L.

    1994-01-01

    The largest portion of Alabama`s rapidly growing poultry industry is geographically concentrated in the Sand Mountain region of northern Alabama. The result is that large amounts of waste are applied to relatively small areas of agricultural soils. A study was conducted to determine the effects of long-term broiler waste (litter) application on environmentally related soil conditions in the region. The region has an average annual rainfall of 1325 mm, which is evenly distributed throughout the year, a thermic temperature regime, and soils in the region are of the Ultisol order. In each of four major broiler-producing counties, three pairs of sites consisting of long-term (15-28 yr) littered and nonlittered fields on matching soil series and maintained under perennial tall fescue (Festuca arundinacea Schreb.) were sampled. Soil cores were taken to 3 m or lithic contact and depth-incremented samples (0-15, 15-30, and each subsequent 30-cm interval) were analyzed for organic C, total N, NO{sub 3}-N, pH, electrical conductivity, and acid-extractable P, K, Ca, Mg, Co, and Zn. Litter application increased organic C and total N to depths of 15 and 30 cm, respectively, as compared with nonlittered soils, whereas pH was 0.5 units higher to a depth of 60 cm under littered soils. Significant accumulation of NO{sub 3}N was found in littered soils to or near bedrock. Extractable P concentrations in littered soils were more than six times greater than in nonlittered soils to a depth of 60 cm. Elevated levels of extractable K, Ca, and Mg to depths greater than 60 cm also were found as a result of long-term litter use. Extractable Cu and Zn had accumulated in littered soils to a depth of 45 cm. These findings indicate that long-term land application of broiler litter, at present rates, has altered soil chemical conditions and has created a potential for adverse environmental impacts in the Sand Mountain region of Alabama. 43 refs., 6 figs., 3 tabs.

  15. Magnetic, dielectric, magnetoelectric properties and impedance spectroscopy of multiferroic Bi1-xNdxFe1-yCoyO3 (x=0, 0.10, 0.15, 0.20, y=0, 0.10) nanoceramics

    NASA Astrophysics Data System (ADS)

    Bera, K. P.; Mandal, P. R.; Nath, T. K.

    2015-06-01

    Single phase multiferroic Bi1-xNdxFe1-yCoyO3 (x=0, 0.10, 0.15, 0.20; y = 0, 0.10) nanoparticles (average particle size 20-80 nm) were synthesized by novel chemical sol-gel route. The detailed microstructural analysis has been performed using HRXRD, HRTEM and FESEM techniques. The Rietveld refinement of the XRD data reveals that the samples are well crystalline with distorted rhombohedral structure having R3c space group without having any iron rich impurity phases. A noticeably large value of dielectric constant (880) and low tan δ loss (0.04) are observed for the sample Bi0.9Nd0.1Fe0.9Co0.1O3 at 100 Hz at room temperature. An anomaly near the Neel temperature in dielectric measurement has been observed for the samples with x = 0.10 and y = 0.0, 0.10. This anomaly has also been found in temperature dependent dielectric loss curve. A spectacular enhancement of Ms (7.26 emu/gm) and coercivity Hc (1.75 T) has been observed for Bi0.9Nd0.1Fe0.9Co0.1O3 nanoceramics revealing ferromagnetic ordering at the ground state (5 K). We have also observed well saturated P-E Hystersis loops with a remanent polarization (Pr) of 0.2 µC/ cm2 and coercive field Ec of 5 kV/cm for Bi0.9Nd0.1Fe0.9Co0.1O3 nanoceramics.

  16. 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.

  17. [Soil nitrogen mineralization under different land use patterns in Xishuangbanna].

    PubMed

    Li, Mingrui; Sha, Liqing

    2005-01-01

    Nitrogen (N) cycle is very important for forest ecosystem, and soil N mineralization rate is often used as the index of soil N availability and its losses. Using Close-Top incubation method, we measured the N mineralization rate in soils (0-15 cm) of monsoon evergreen broadleaf forest, seasonal rain forest, rubber plantation, heavily disturbed seasonal rain forest, Millettia laptobotrya secondary forest and upland rice field. The results showed that the net N mineralization rate and N nitrification rate were decreased in the sequence of heavily disturbed seasonal rain forest > Millettia laptobotrya secondary forest > seasonal rain forest > monsoon evergreen broadleaf forest > rubber plantation > upland rice field. Rubber plantation and upland rice field were the most seriously disturbed land use patterns. Their soil N storage and mineralization rate were very low and exhibited significant variations, compared with other land use patterns. Lower net N mineralization rate correlated with lower N storage, and also, with lower fungi numbers. The N mineralization rate in disturbed forest soil which had recovered for several years was similar to that in primary forest soil, but decreased significantly when the forests were converted to agricultural land.

  18. Nitrogen mineralization and nitrate leaching of a sandy soil amended with different organic wastes.

    PubMed

    Burgos, Pilar; Madejón, Engracia; Cabrera, Francisco

    2006-04-01

    Organic wastes can be recycled as a source of plant nutrients, enhancing crop production by improving soil quality. However, the study of the dynamic of soil nutrient, especially the N dynamic, after soil application of any organic material is vital for assessing a correct and effective use of the material, minimizing the losses of nitrate in leachates and avoiding the negative environmental effects that it may cause in groundwater. To estimate the effect of three organic materials, a municipal solid waste compost (MWC), a non-composted paper mill sludge (PS), and an agroforest compost (AC) on the N dynamic of a sandy soil two experiments were carried out: an incubation experiment and a column experiment. The incubation experiment was conducted to estimate the N mineralization rate of the different soil-amendment mixtures. The soil was mixed with the organic amendments at a rate equivalent to 50,000 kg ha(-1) and incubated during 40 weeks at constant moisture content (70% of its water-holding capacity) and temperature (28 degrees C) under aerobic conditions. Organic amendment-soil samples showed an immobilization of N during the first weeks, which was more noticeable and longer in the case of PS-treated soil compared to the other two amendments due to its high C/N ratio. After this immobilization stage, a positive mineralization was observed for all treatment, especially in MWC treated soil. Contemporaneously a 1-year column (19 cm diameter and 60 cm height) experiment was carried out to estimate the nitrate losses from the soil amended with the same organic materials. Amendments were mixed with the top soil (0-15 cm) at a rate equivalent to 50,000 kg ha(-1). The columns were periodically irrigated simulating rainfall in the area of study, receiving in total 415 mm of water, and the water draining was collected during the experimental period and analysed for NO3-N. At the end of the experimental period NO3-N content in soil columns at three depths (0-20, 20-35 and

  19. Nitrogen mineralization and nitrate leaching of a sandy soil amended with different organic wastes.

    PubMed

    Burgos, Pilar; Madejón, Engracia; Cabrera, Francisco

    2006-04-01

    Organic wastes can be recycled as a source of plant nutrients, enhancing crop production by improving soil quality. However, the study of the dynamic of soil nutrient, especially the N dynamic, after soil application of any organic material is vital for assessing a correct and effective use of the material, minimizing the losses of nitrate in leachates and avoiding the negative environmental effects that it may cause in groundwater. To estimate the effect of three organic materials, a municipal solid waste compost (MWC), a non-composted paper mill sludge (PS), and an agroforest compost (AC) on the N dynamic of a sandy soil two experiments were carried out: an incubation experiment and a column experiment. The incubation experiment was conducted to estimate the N mineralization rate of the different soil-amendment mixtures. The soil was mixed with the organic amendments at a rate equivalent to 50,000 kg ha(-1) and incubated during 40 weeks at constant moisture content (70% of its water-holding capacity) and temperature (28 degrees C) under aerobic conditions. Organic amendment-soil samples showed an immobilization of N during the first weeks, which was more noticeable and longer in the case of PS-treated soil compared to the other two amendments due to its high C/N ratio. After this immobilization stage, a positive mineralization was observed for all treatment, especially in MWC treated soil. Contemporaneously a 1-year column (19 cm diameter and 60 cm height) experiment was carried out to estimate the nitrate losses from the soil amended with the same organic materials. Amendments were mixed with the top soil (0-15 cm) at a rate equivalent to 50,000 kg ha(-1). The columns were periodically irrigated simulating rainfall in the area of study, receiving in total 415 mm of water, and the water draining was collected during the experimental period and analysed for NO3-N. At the end of the experimental period NO3-N content in soil columns at three depths (0-20, 20-35 and

  20. 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.

  1. 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.

  2. CV and CM chondrite impact melts

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    SciTech Connect

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

    2015-08-01

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

  4. The Isiokpo oil-pipeline leakage: total organic carbon/organic matter contents of affected soils.

    PubMed

    Osuji, Leo C; Adesiyan, Samuel O

    2005-08-01

    The environmental impact of the 1997 leakage of the high-pressure crude-oil pipeline at Isiokpo in the Niger Delta in the southeast of Nigeria was evaluated, with particular reference to total-organic-carbon (TOC) and total-organic-matter (TOM) contents of soils within the vicinity of the oil spillage. The soils, taken from depths of 0-15 cm (surface) and 15-30 cm (subsurface), were found to be more acidic (pH 4.2-5.6) than the unpolluted soils, with a high average moisture content of 6.8%. The extractable hydrocarbon content ranged from 2.71-3.48 mg/kg, indicating hydrocarbon contamination. However, contrary to expectation, the TOC and TOM contents of the polluted soils did not show any significant increase in concentration, supposedly due to natural rehabilitation of the affected mat layer of soils. Thus, notwithstanding the possible proliferation of heterotrophic organisms by the presence of the added petroleum hydrocarbons, environmental conditions such as weathering and climatic predispositions, as well as physico-chemical parameters such as pH, moisture content, and temperature must have encumbered the carbon-mineralizing capacity of the heterotrophs, thereby reducing the turnover of carbon and the decomposition of organic matter. The restrictions by high moisture content might not come directly from H(2)O itself, but are probably a consequence of hindered soil ventilation, which reduces O(2) supply and gaseous diffusion, conditions that might have been substantially aggravated by the added petroleum hydrocarbons.

  5. Characterization of 8-cm engineering model thruster

    NASA Technical Reports Server (NTRS)

    Williamson, W. S.

    1984-01-01

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

  6. The Multidimensional Curriculum Model (MdCM)

    ERIC Educational Resources Information Center

    Vidergor, Hava E.

    2010-01-01

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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Hydrostatic pressure tuned magneto-structural transition and occurrence of pressure induced exchange bias effect in Mn0.85Fe0.15NiGe alloy

    NASA Astrophysics Data System (ADS)

    Dutta, P.; Pramanick, S.; Das, D.; Chatterjee, S.

    2016-09-01

    The magnetic and magneto-functional behavior of a Fe-doped MnNiGe alloy with nominal composition Mn0.85Fe0.15NiGe have been investigated in ambient as well as in high pressure conditions. The alloy undergoes a first order martensitic phase transition (MPT) around 200 K and also shows a large conventional magnetocaloric effect (MCE) ( Δ S∼ -21 J kg‑1 K‑1 for magnetic field (H) changing from 0–50 kOe) around the transition in ambient conditions. The application of external hydrostatic pressure (P) results in a shift in MPT towards the lower temperature and a clear decrease in the saturation moment of the alloy at 5 K. The peak value of MCE is also found to decrease with increasing external P (∼18 J kg‑1 K‑1 decrease in Δ S has been observed for P  =  12.5 kbar). The most interesting observation is the occurrence of the exchange bias effect (EBE) on application of external P. The competing ferromagnetic and antiferromagnetic interaction in the presence of external P plays the pivotal role towards the observation of P induced EBE.

  12. Hydrostatic pressure tuned magneto-structural transition and occurrence of pressure induced exchange bias effect in Mn0.85Fe0.15NiGe alloy

    NASA Astrophysics Data System (ADS)

    Dutta, P.; Pramanick, S.; Das, D.; Chatterjee, S.

    2016-09-01

    The magnetic and magneto-functional behavior of a Fe-doped MnNiGe alloy with nominal composition Mn0.85Fe0.15NiGe have been investigated in ambient as well as in high pressure conditions. The alloy undergoes a first order martensitic phase transition (MPT) around 200 K and also shows a large conventional magnetocaloric effect (MCE) ( Δ S˜ -21 J kg-1 K-1 for magnetic field (H) changing from 0-50 kOe) around the transition in ambient conditions. The application of external hydrostatic pressure (P) results in a shift in MPT towards the lower temperature and a clear decrease in the saturation moment of the alloy at 5 K. The peak value of MCE is also found to decrease with increasing external P (˜18 J kg-1 K-1 decrease in Δ S has been observed for P  =  12.5 kbar). The most interesting observation is the occurrence of the exchange bias effect (EBE) on application of external P. The competing ferromagnetic and antiferromagnetic interaction in the presence of external P plays the pivotal role towards the observation of P induced EBE.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. 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.

    2016-09-01

    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.

  15. Hysteresis in the RF-Induced Flux Lattice Annealing (RIFLA) of the superconducting state in Pr1.85Ce0.15CuO4-y

    NASA Astrophysics Data System (ADS)

    Clark, W. G.; Brown, S. E.; Gaidos, G.; Greene, R. L.; Balci, H.

    2010-03-01

    We report hysteresis in flux lattice (FL) annealing by an rf magnetic field for the cuprate superconductor Pr1.85Ce0.15CuO4-y. A strained FL is formed by placing the sample in the coil (inductance L) of a tuned NMR probe circuit and rotating the coil and sample in a fixed B at low temperature. A series of rf pulses in the coil generates an alternating magnetic field that anneals the FL. It decreases the sample's rf skin depth, which reduces L and increases the resonant frequency (f) of the probe. Rotation in small steps about an axis parallel to the CuO planes and perpendicular to B with annealing after each step generates a peak in f whose shape is the same for rotation in both directions (no rotation hysteresis) and is a maximum for B parallel to the CuO planes. When rotation is done in both directions without annealing, the substantial hysteresis reported here occurs. This work was supported at UCLA by NSF Grants DMR-0334869 and DMR-0804625, and at U. Maryland by NSF Grant DMR- 0653535.

  16. Dielectric and structural properties of diffuse ferroelectric phase transition in Pb1.85K1.15Li0.15Nb5O15 ceramic

    NASA Astrophysics Data System (ADS)

    Choukri, E.; Gagou, Y.; Mezzane, D.; Abkhar, Z.; El Moznine, R.; Luk'yanchuk, I.; Saint-Grégoire, P.; Kavokin, A. V.

    2011-02-01

    We studied the structural and dielectric properties of new Tetragonal Tungsten Bronze (TTB) ceramics Pb1.85K1.15Li0.15Nb5O15 that was synthesized by solid-state reaction. We pay a special attention to the diffuse phase transition (DPT) that occurs close to 425 °C. Using dielectric measurements in a frequency range of 10 Hz-1 MHz and in the temperature range 30-560 °C, we have shown that the real permittivity close to DPT is well described by Santos-Eiras phenomenological model. Space-charge polarization, relaxation phenomena and free charges conductivity have been analyzed using dielectric spectroscopy impedance and modulus characterization. Cole-Cole plots show a non-Debye (polydispersive) type relaxation. In paraelectric phase the Arrhenius activation energy was determined as Eτ = 0.72 eV. We demonstrated that frequency dependence of ac conductivity at different temperatures obeys the Jonscher's universal law: σac = σdc + A(ω)n.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  18. Anisotropic magnetostriction in a <110> oriented crystal Tb0.36Dy0.64(Fe0.85Co0.15)2 after coaxial field annealing

    NASA Astrophysics Data System (ADS)

    Zhang, Changsheng; Ma, Tianyu; Qi, Ruilei; Yan, Mi

    2010-08-01

    Axial magnetostriction of Terfenol-D oriented crystals is highly anisotropic when changing the magnetization direction. Magnetostrictions of a ⟨110⟩ oriented crystal Tb0.36Dy0.64(Fe0.85Co0.15)2 were investigated under magnetic fields with a series of angles θ to its axis. Totally different anisotropic magnetostrictive behaviors are observed after annealing under a coaxial field of 240 kA/m. The magnetostriction for the field annealed specimen seems unsaturated even under 640 kA/m for angles θ in the range from 0° to 55°. At these angles, magnetostriction "ascending" is observed during the final magnetization process, while magnetostriction "dropping" occurs at angles above 35° for the untreated crystal. With the increase in angle θ, the corresponding field where magnetostriction starts dropping decreases for the untreated crystal, while the field at which magnetostriction starts ascending increases for the field annealed one. A simplified model based on moment "jump" and "rotation" is proposed to explain such anisotropic behaviors.

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-08-01

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

  3. 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.

  4. 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

  5. Balloon observations of the radiance of the earth between 2100 cm(-1) and 2700 cm(-1).

    PubMed

    Shaw, J H; McClatchey, R A; Schaper, P W

    1967-02-01

    A grating spectrometer capable of measuring small radiation fluxes with a spectral resolution of 95 at 4.3 micro is described. Bands of CO(2), N(2)O, and O(3) are identified in spectra between 2100 cm(-1) and 2700 cm(-1) of the earth and lower atmosphere obtained from an altitude of 30 km with this instrument. Scattering of solar radiation by clouds was observed between 2400 cm(-1) and 2700 cm(-1). A temperature profile of the atmosphere to 30 km determined from an analysis of the measurements in the region of the 4.3 micro CO(2) band is compared with radiosonde observations made during the flight.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  7. Magnetic susceptibility of curium pnictides. [/sup 248/CmP, /sup 248/CmSb

    SciTech Connect

    Nave, S.E.; Huray, P.G.; Peterson, J.R.; Damien, D.A.; Haire, R.G.

    1981-09-01

    The magnetic susceptibility of microgram quantities of /sup 248/CmP and /sup 248/CmSb has been determined with the use of a SQUID micromagnetic susceptometer over the temperature range 4.2 to 340 K and in the applied magnetic field range of 0.45 to 1600 G. The fcc (NaCl-type) samples yield magnetic transitions at 73K and 162 K for the phosphide and antimonide, respectively. Together with published magnetic data for CmN and CmAs, these results indicate spatially extended exchange interactions between the relatively localized 5f electrons of the metallic actinide atoms.

  8. 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.

  9. 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.

  10. Late type close binary system CM Dra

    NASA Astrophysics Data System (ADS)

    Kalomeni, Belinda

    2015-08-01

    In this study, we present new observations of the close binary system CM Dra. We analyzed all the available data of the system and estimated the physical parameters of the system stars highly accurately. Using the newly obtained parameters the distance of the system is determined to be 11.6 pc. A possible giant planet orbiting the close binary system has been detected. This orbital period would likely make it one of the longest known orbital period planet.

  11. 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

  12. Constraining dark matter through 21-cm observations

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  13. 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.

  14. 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

  15. Remediation of saline-sodic soil with flue gas desulfurization gypsum in a reclaimed tidal flat of southeast China.

    PubMed

    Mao, Yumei; Li, Xiaping; Dick, Warren A; Chen, Liming

    2016-07-01

    Salinization and sodicity are obstacles for vegetation reconstruction of coastal tidal flat soils. A study was conducted with flue gas desulfurization (FGD)-gypsum applied at rates of 0, 15, 30, 45 and 60Mg/ha to remediate tidal flat soils of the Yangtze River estuary. Exchangeable sodium percentage (ESP), exchangeable sodium (ExNa), pH, soluble salt concentration, and composition of soluble salts were measured in 10cm increments from the surface to 30cm depth after 6 and 18months. The results indicated that the effect of FGD-gypsum is greatest in the 0-10cm mixing soil layer and 60Mg/ha was the optimal rate that can reduce the ESP to below 6% and decrease soil pH to neutral (7.0). The improvement effect was reached after 6months, and remained after 18months. The composition of soluble salts was transformed from sodic salt ions mainly containing Na(+), HCO3(-)+CO3(2-) and Cl(-) to neutral salt ions mainly containing Ca(2+) and SO4(2-). Non-halophyte plants were survived at 90%. The study demonstrates that the use of FGD-gypsum for remediating tidal flat soils is promising.

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

    PubMed

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

    2016-05-18

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

  17. The specific heat of the electron-doped La-1038 compound (Ca0.85La0.15)10(FeAs)10(Pt3As8).

    PubMed

    Kim, J S; Stürzer, T; Johrendt, D; Stewart, G R

    2013-04-01

    The specific heat of polycrystalline (Ca0.85La0.15)10(FeAs)10(Pt3As8), an electron-doped iron-based superconductor (T(c)(onset) = 34.6 K) with Ca/La ions and Pt3As8 separating the FeAs layers, was measured between 0.4 and 48 K.This compound has been recently reported to represent an electron-doped variant of the non-superconducting 10-3-8 phase, featuring a superconducting transition in the range of that of the 10-4-8 phase. This family of compounds is unique among the iron pnictide superconductors discovered to date due to the second metal pnictide layer, Pt3As8, present in the structure competing with the familiar FeAs layer for the electron from the Ca/La. This superconductor is further unusual in that it has a rather low crystalline symmetry (triclinic) for such a high superconducting transition temperature. The specific heat γ is found to be approximately 26 mJ/(Ca/La mol)K(2), comparable to 122 iron-based superconductors electron-doped on the Fe sites and a factor of two smaller than 122 compounds hole-doped on the cation site, e.g., Ba(1-x)K(x)Fe2As2. The present work also investigates the discontinuity in the specific heat at T(c), ΔC, to compare with the global trend, established by Bud'ko, Ni and Canfield (BNC), of ΔC/T(c) versus T(c) found for essentially all iron-based superconductors. The result is a value lower than the BNC trend by a factor of ten, consistent with a severely broadened superconducting transition.

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

    SciTech Connect

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

    1998-10-01

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

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

    PubMed

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

    2016-05-18

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

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

    SciTech Connect

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

    2011-09-15

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

  1. 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.

  2. Practical aspects involved in the design and set up of a 0.15 T, 6-coil resistive magnet, whole body NMR imaging facility.

    PubMed

    Thomas, S R; Ackerman, J L; Kereiakes, J G

    1984-01-01

    Many technical and logistical questions must be addressed when planning the installation of an NMR imaging system. These considerations become particularly significant when the facility is being established within an existing medical center complex. This paper presents a report on the practical aspects and experience obtained in siting a 6-coil 0.15 T resistive magnet system. The topics discussed include: floor loading; ferromagnetic environment; the effect of iron on the magnet field strength and homogeneity characteristics; shimming procedures; temperature stability requirements; rf shielding; and effects of the magnetic field on common medical instrumentation and magnetic media. It was found that the field shift as a function of the distance of a steel mass from the center of the magnet exhibited an (1/r)5.2 +/- 0.5 to (1/r) 4.2 +/- 0.3 dependence for axial and radial positions respectively which, as expected, is somewhat weaker than the (1/r)6 dependence expected by point dipole approximations. Field distortions caused by the presence of ferromagnetic material in radial positions may be essentially fully compensated with first order transverse shim coils (most conveniently, the x and y imaging gradient coils could be used). Axially distributed material requires, in addition to first order z-gradient correction, higher order axial shim compensation. The temperature stability of the magnet system over the scan period must be better than 0.2 degrees C to insure that temperature-induced field fluctuations are less than the intrinsic static inhomogeneity: and, ideally, below 0.01 degrees C to reduce these fluctuations to less than those caused by power supply instability.

  3. Decay Data Evaluation Project (DDEP): evaluation of the main 243Cm and 245Cm decay characteristics.

    PubMed

    Chechev, Valery P

    2012-09-01

    The results of new decay data evaluations are presented for (243)Cm (α) decay to nuclear levels in (239)Pu and (245)Cm (α) decay to nuclear levels in (241)Pu. These evaluated data have been obtained within the Decay Data Evaluation Project using information published up to 2011.

  4. [Effects of biochar amendment on cropland soil bulk density, cation exchange capacity, and particulate organic matter content in the North China Plain].

    PubMed

    Chen, Hong-Xia; Du, Zhang-Liu; Guo, Wei; Zhang, Qing-Zhong

    2011-11-01

    A 3-year field experiment with randomized block design was conducted to study the effects of biochar amendment on the soil bulk density, cation exchange capacity (CEC), and particulate organic matter C (POM-C) and N (POM-N) contents in a high-yielding cropland in the North China Plain. Four treatments were installed, i.e., chemical NPK (CK), chemical NPK plus 2250 kg x hm(-2) of biochar (C1), chemical NPK plus 4500 kg x hm(-2) of biochar (C2), and 750 kg x hm(-2) of biochar-based slow release fertilizer (CN). Comparing with CK, treatments C1 and C2 significantly decreased the bulk density of 0-7.5 cm soil layer by 4.5% and 6.0%, respectively, and the treatments with biochar amendment increased the CEC in 0-15 cm soil layer, with an increment of 24.5% in treatment C2. Biochar amendment also increased the C (POM-C) and N (POM-N) contents in 0-7.5 cm soil layer, e.g., the POM-C and N contents in treatment C1 and C2 were 250% and 85%, and 260% and 120% higher than those of the CK, respectively. After three years of biochar amendment, the soil had obvious improvement in its physical and chemical properties, and played more active roles in soil carbon sequestration and greenhouse gases emission reduction. PMID:22303671

  5. 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.

  6. 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.

  7. Snowmelt timing alters shallow but not deep soil moisture in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Blankinship, Joseph C.; Meadows, Matthew W.; Lucas, Ryan G.; Hart, Stephen C.

    2014-02-01

    Roughly one-third of the Earth's land surface is seasonally covered by snow. In many of these ecosystems, the spring snowpack is melting earlier due to climatic warming and atmospheric dust deposition, which could greatly modify soil water resources during the growing season. Though snowmelt timing is known to influence soil water availability during summer, there is little known about the depth of the effects and how long the effects persist. We therefore manipulated the timing of seasonal snowmelt in a high-elevation mixed-conifer forest in a Mediterranean climate during consecutive wet and dry years. The snow-all-gone (SAG) date was advanced by 6 days in the wet year and 3 days in the dry year using black sand to reduce the snow surface albedo. To maximize variation in snowmelt timing, we also postponed the SAG date by 8 days in the wet year and 16 days in the dry year using white fabric to shade the snowpack from solar radiation. We found that deeper soil water (30-60 cm) did not show a statistically significant response to snowmelt timing. Shallow soil water (0-30 cm), however, responded strongly to snowmelt timing. The drying effect of accelerated snowmelt lasted 2 months in the 0-15 cm depth and at least 4 months in the 15-30 cm depth. Therefore, the legacy of snowmelt timing on soil moisture can persist through dry periods, and continued earlier snowmelt due to climatic warming and windblown dust could reduce near-surface water storage and availability to plants and soil biota.

  8. 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.

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

    PubMed

    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

  10. 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

  11. Vertical variations in the concentration of mercury in soils around Sakurajima Volcano, Southern Kyushu, Japan.

    PubMed

    Tomiyasu, Takashi; Okada, Morimichi; Imura, Ryusuke; Sakamoto, Hayao

    2003-03-20

    In an effort to estimate the influence of mercury emitted from Sakurajima Volcano, Southern Kyushu, Japan, on the accumulation of mercury in soil, the vertical distribution of total mercury in soils was investigated together with organic matter content and grain size. The soils were sampled at a thickness of 1 cm from the surface to depth of 1 m at five locations on Sakurajima and two control locations, i.e. Takatoge approximately 11 km southeast and Suzuyama 22 km southwest of the volcano. The concentration in soils increased with the distance from the volcano and was 6.5+/-1.9 ngg(-1) (n=335), 29.0+/-15.6 ngg(-1) (n=100) and 229+/-105 ngg(-1) (n=103) for Sakurajima, Takatoge and Suzuyama, respectively. The concentration of mercury correlated with the amount of organic matter, but not with grain size distribution. The sedimentation rate for Sakurajima, Takatoge and Suzuyama was estimated from geological data to be approximately 1.3, 0.083 and 0.0048 cmyear(-1), respectively. The relatively fast sedimentation of Sakurajima soil was caused by the frequent precipitation of volcanic ash. The annual deposition of mercury estimated for Sakurajima, Takatoge and Suzuyama from the mercury concentration, sedimentation rate and soil density was 9 x 10(4), 3 x 10(4) and 2 x 10(4) ngm(-2)year(-1), respectively. Although the soil of Sakurajima had the lowest concentration among the three sites, it received the largest amount of mercury.

  12. 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.

    2015-03-01

    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-field-based soil fertility assessment procedures, hereafter referred to as farmer' field experiences (FFE), for ease of use (simplicity) 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 approaches, as low, medium and high in terms of soil fertility, with maize as the test crop. Based on maize yield, both rating techniques were fairly precise in delineating soil fertility classes, though the FFE approach showed mixed responses. Soil organic carbon in the top soil (0-15 cm) was exceptionally influential, explaining > 70% in yield variance. Each unit rise in SOC concentration resulted in 966-1223 kg ha-1 yield gain. The FFE approach was effective in identifying low fertility fields, which was coherent with the fields categorized as low (SOC < 1.2%). Beyond this level, its precision can be remarkably increased when supplemented with the SOC procedure.

  13. 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.

  14. Vertical variations in the concentration of mercury in soils around Sakurajima Volcano, Southern Kyushu, Japan.

    PubMed

    Tomiyasu, Takashi; Okada, Morimichi; Imura, Ryusuke; Sakamoto, Hayao

    2003-03-20

    In an effort to estimate the influence of mercury emitted from Sakurajima Volcano, Southern Kyushu, Japan, on the accumulation of mercury in soil, the vertical distribution of total mercury in soils was investigated together with organic matter content and grain size. The soils were sampled at a thickness of 1 cm from the surface to depth of 1 m at five locations on Sakurajima and two control locations, i.e. Takatoge approximately 11 km southeast and Suzuyama 22 km southwest of the volcano. The concentration in soils increased with the distance from the volcano and was 6.5+/-1.9 ngg(-1) (n=335), 29.0+/-15.6 ngg(-1) (n=100) and 229+/-105 ngg(-1) (n=103) for Sakurajima, Takatoge and Suzuyama, respectively. The concentration of mercury correlated with the amount of organic matter, but not with grain size distribution. The sedimentation rate for Sakurajima, Takatoge and Suzuyama was estimated from geological data to be approximately 1.3, 0.083 and 0.0048 cmyear(-1), respectively. The relatively fast sedimentation of Sakurajima soil was caused by the frequent precipitation of volcanic ash. The annual deposition of mercury estimated for Sakurajima, Takatoge and Suzuyama from the mercury concentration, sedimentation rate and soil density was 9 x 10(4), 3 x 10(4) and 2 x 10(4) ngm(-2)year(-1), respectively. Although the soil of Sakurajima had the lowest concentration among the three sites, it received the largest amount of mercury. PMID:12663186

  15. 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.

  16. 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.

  17. Combining galaxy and 21-cm surveys

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  18. The Metallicity of the CM Draconis System

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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 (lsim 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.

  19. 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.

  20. Spin dynamics in the La1.85Sr0.15Cu1-xFexO4 system probed by ESR

    NASA Astrophysics Data System (ADS)

    Cieplak, Marta Z.; Sienkiewicz, A.; Mila, F.; Guha, S.; Xiao, Gang; Xiao, J. Q.; Chien, C. L.

    1993-08-01

    We study the magnetic properties of the La1.85Sr0.15Cu1-xFexO4 system (x=0-0.1) in the vicinity of the metal-insulator (MI) transition using static-susceptibility measurements and the electron-spin resonance (ESR) of the Fe ions. Spin-glass (SG) freezing is present for all nonsuperconducting specimens. The iron ESR line broadens on approaching the freezing temperature, similarly to the effect observed in canonical spin glasses. This broadening can be attributed to the influence of the slowing down of spin fluctuations on the spin-spin relaxation rate. It depends differently on x on the two different sides of the MI transition suggesting the existence of two different SG phases: insulating (ISG) where the Fe spins couple to the Cu-spin array by superexchange interactions, and metallic (MSG), where there exists, in addition, Ruderman-Kittel-Kasuya-Yosida-like coupling mediated by the free carriers. The proximity of the MI transition suppresses this coulping, giving rise to the observed dependence of the paramagnet -SG phase boundary on x. In the MSG phase, at high temperatures, the spin-lattice relaxation mechanism is also mediated by the free carriers. It differs from the analogous process observed in conventional metals in that the ESR linewidth increases with increasing T faster than linearly. We explain this behavior by assuming that the effective magnetic field felt by the Fe moments originates mainly from the spins of holes located on the nearest-neighbor oxygen ions. The linewidth divided by T which probes the dynamical susceptibility at the Fe site varies as a+bT. Here a goes to zero as the MI transition is approached and so plays the role of the Pauli susceptibility of the free carriers, whereas b is independent of x in the vicinity of the MI transition but decreases for small Fe dopings away from the MI transition and may be identified as originating from the antiferromagnetic spin fluctuations in the system.

  1. Comparison of paramagnetic- and nonmagnetic-impurity effects on superconductivity in Nd sub 1. 85 Ce sub 0. 15 CuO sub 4

    SciTech Connect

    Sugiyama, J.; Tokuono, S.; Koriyama, S.; Yamauchi, H.; Tanaka, S. )

    1991-05-01

    The effects of substitution of Co, Ni, or Zn for Cu in the electron-doped superconductors, Nd{sub 1.85}Ce{sub 0.15}Cu{sub 1{minus}{ital x}M{ital x}}O{sub 4} (with {ital M}=Co, Ni, or Zn, {ital x}{le}0.05), have been investigated by powder x-ray diffraction analysis and resistivity, magnetic-susceptibility, and Hall-coefficient measurements. It is observed that only 0.7% Co or 0.8% Ni substitution for Cu destroys superconductivity. On the contrary, for the Zn-substituted samples, it is observed that {ital T}{sub {ital c}} decreases proportionally to {ital x} and the magnitude of {ital T}{sub {ital c}} is {similar to}9 K even for the 2% Zn-substituted sample. This result suggests that the pair-breaking effect plays a dominant role in the suppression of superconductivity in the Co- or Ni-substitute samples. The absolute values of the exchange-interaction energy between an electron and a Co ion and of that between an electron and a Ni ion are estimated at {similar to}0.09 and {similar to}0.08 eV, respectively. These values are comparable to those of the conventional BCS-type superconductors containing paramagnetic impurities. Both the absolute value of the Hall coefficient ({vert bar}{ital R}{sub {ital H}}{vert bar}) and its temperature coefficient ({ital d}{vert bar}{ital R}{sub {ital H}}{vert bar}/{ital dT}) are found to decrease as {ital x} increases for all the samples at temperatures higher than 120 K. However, for the Co-substituted samples, it is clearly observed that {vert bar}{ital R}{sub {ital H}}{vert bar} increases proportionally to {ital x} at 30 K, while {vert bar}{ital R}{sub {ital H}}{vert bar} decreases monotonically with increasing {ital x} for the Ni- or Zn-substitute samples. Therefore, it seems that there are no clear relations between the temperature dependence of {ital R}{sub {ital H}} and the suppression in the magnitude of {ital T}{sub {ital c}} due to the substitutional effects.

  2. 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

  3. 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.

  4. 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.

  5. Overcoming the Challenges of 21cm Cosmology

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan

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

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

    SciTech Connect

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

    2004-10-15

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

  7. 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

  8. 70-cm radar observations of 433 Eros

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  9. NASA 30 Cm Ion Thruster Development Status

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  10. 21 Cm Tomography With the Alfalfa Survey

    NASA Astrophysics Data System (ADS)

    Fry, Alexander B.; Boutan, C.; Carroll, P. A.; Hazelton, B.; Morales, M. F.

    2011-01-01

    Neutral hydrogen (HI) 21cm intensity mapping, or HI tomography is a promising technique being utilized by several upcoming experiments (LOFAR, MWA, SKA). The measurement of volume averaged neutral hydrogen mass density in synoptic sky surveys can be applied to the study of the HI mass function, the distribution of large scale structure, the reionization of the universe, and the expansion history of the universe through such standard rulers as baryonic acoustic oscillations. In order to prepare for future experiments, in particular the Murchison Widefield Array (MWA), we analyze the Arecbo Legacy Fast ALFA (Arecibo L-Band Feed Array) Feed Array (ALFALFA) survey data to probe the spatial density variations of HI in our local universe (z <0.06) where data is currently available. We address challenges unique to data of this kind, such as identifying and subtracting out signal from RFI and local galactic sources, and characterizing the ALFA array beam pattern which dictates sensitivity and resolution.

  11. 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.

  12. [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.

  13. 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

  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. PMID:25611821

  15. 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.

  16. 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.

  17. 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

  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. Heavy metals in soils and crops in Southeast Asia. 2. Thailand.

    PubMed

    Zarcinas, Bernhard A; Pongsakul, Pichit; McLaughlin, Mike J; Cozens, Gill

    2004-12-01

    A reconnaissance soil geochemical and concomitant plant survey based on 318 soil (0-15 cm) and 122 plant samples was used for the assessment of heavy metal pollution of agricultural soils and crops of Thailand. Arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) were determined in soils using aqua regia digestion, and in plants using nitric acid digestion. Organic carbon (C), pH, electrical conductivity (EC) and available phosphorus (P) were determined on the soil samples using appropriate procedures. Results indicated that concentrations of heavy metals varied widely among the different regions of Thailand. Regression analysis between the concentrations of metals in soil (aqua regia extractable) and edible plant parts indicated a small but positive relationship for Cd in all the plants sampled in the survey (R2 = 0.081, p < 0.001). There was also a positive relationship between soil and plant Cd concentrations in rice (R2 = 0.242, p < 0.010), and negative relationships for Zn in rice (R2 = 0.385, p < 0.001), and Cu (R2 = 0.355, p < 0.001) and Zn (R2 = 0.122, p < 0.026) in glutinous rice. Principal component analysis of the soil data suggested that concentrations of As, Co, Cr, Cu, Hg, Ni and Pb were strongly correlated with concentrations of Al and Fe, which is suggestive of evidence of background variations due to changes in soil mineralogy. Thus, the evidence for widespread contamination of soils by these elements through agricultural activities is not strong. On the other hand, Cd and Zn were strongly correlated with organic matter and concentrations of available and aqua regia extractable P. This is attributed to input of contaminants in agricultural fertilisers and soil amendments (e.g. manures, composts).

  20. Heavy metals in soils and crops in Southeast Asia. 2. Thailand.

    PubMed

    Zarcinas, Bernhard A; Pongsakul, Pichit; McLaughlin, Mike J; Cozens, Gill

    2004-12-01

    A reconnaissance soil geochemical and concomitant plant survey based on 318 soil (0-15 cm) and 122 plant samples was used for the assessment of heavy metal pollution of agricultural soils and crops of Thailand. Arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) were determined in soils using aqua regia digestion, and in plants using nitric acid digestion. Organic carbon (C), pH, electrical conductivity (EC) and available phosphorus (P) were determined on the soil samples using appropriate procedures. Results indicated that concentrations of heavy metals varied widely among the different regions of Thailand. Regression analysis between the concentrations of metals in soil (aqua regia extractable) and edible plant parts indicated a small but positive relationship for Cd in all the plants sampled in the survey (R2 = 0.081, p < 0.001). There was also a positive relationship between soil and plant Cd concentrations in rice (R2 = 0.242, p < 0.010), and negative relationships for Zn in rice (R2 = 0.385, p < 0.001), and Cu (R2 = 0.355, p < 0.001) and Zn (R2 = 0.122, p < 0.026) in glutinous rice. Principal component analysis of the soil data suggested that concentrations of As, Co, Cr, Cu, Hg, Ni and Pb were strongly correlated with concentrations of Al and Fe, which is suggestive of evidence of background variations due to changes in soil mineralogy. Thus, the evidence for widespread contamination of soils by these elements through agricultural activities is not strong. On the other hand, Cd and Zn were strongly correlated with organic matter and concentrations of available and aqua regia extractable P. This is attributed to input of contaminants in agricultural fertilisers and soil amendments (e.g. manures, composts). PMID:15719159

  1. ICD-9-CM to ICD-10-CM Codes: What? Why? How?

    PubMed Central

    Cartwright, Donna J.

    2013-01-01

    The wound care industry will gain many benefits when International Classification of Diseases (ICD)-10-Clinical Modification (CM) is implemented. One of the main benefits is that the disease classifications will be consistent with current clinical practice and medical technology advances. The new classification codes will be very granular, which means the level of specificity will greatly improve. Numerous new codes will represent more specific anatomic sites, etiologies, comorbidities, and complications, and will improve the ability to demonstrate severity of illness. For instance, the new feature of laterality is directly built into the new codes: separate codes will distinguish right, left, and bilateral, where needed. The increased granularity will provide better analysis of disease patterns and outbreak of disease. Additionally, the United States will finally be using the same diagnosis coding system as the rest of the world. This article will describe what the ICD-9-CM/ICD-10-CM codes are, why they are so important, and how clinicians and researchers will convert from ICD-9-CM to ICD-10-CM effective October 1, 2014. PMID:24761333

  2. 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

  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. 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.

  5. 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.

  6. 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

  7. 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

  8. A sub-cm micromachined electron microscope

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  9. 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.

  10. Hazardous concentrations of selenium in soil and groundwater in North-West India.

    PubMed

    Bajaj, Mini; Eiche, Elisabeth; Neumann, Thomas; Winter, Josef; Gallert, Claudia

    2011-05-30

    Soil and groundwater samples were collected for bulk elemental analyses in particular for selenium (Se) concentrations from six agricultural sites located in states of Punjab and Haryana in North-West India. Toxic concentrations of Se (45-341 μg L(-1)) were present in groundwater (76 m deep) of Jainpur and Barwa villages in Punjab. Selenium enrichments were also found in top soil layers (0-15 cm) of Jainpur (2.3-11.6 mg kg(-1)) and Barwa (3.1 mg kg(-1)). Mineralogical analyses confirmed silicates and phyllosilicates as main components of these soils, also reflected by the high content of SiO(2) (40-62 wt.%), Al(2)O(3) (9-21 wt.%) and K(2)O (2.2-3.2 wt.%). Prevailing intensive irrigation practices in Punjab with Se enriched groundwater may be the cause of Se accumulation in soils. Sequential extraction revealed >50% Se bioavailability in Jainpur soils. Appearance of selenite was observed in some of the batch assays with soil slurries under reducing conditions. Although safe Se concentrations were found in Hisar, Haryana, yet high levels of As, Mo and U present in groundwater indicated its unsuitability for drinking purposes. Detailed biogeochemical studies of Se in sediments or groundwater of Punjab are not available so far; intensive investigations should be started for better understanding of the problem of Se toxicity.

  11. 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

  12. [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.

  13. Characteristics of N2O production and transport within soil profiles subjected to different nitrogen application rates in China.

    PubMed

    Nan, Weige; Yue, Shanchao; Li, Shiqing; Huang, Haizhou; Shen, Yufang

    2016-01-15

    To better understand the effect of N fertilizer on the responses of subsoil N2O to N2O emissions in a high-yield plot, we investigated the subsurface N2O concentrations at seven mineral soil depths and analyzed the subsoil N2O fluxes between soil horizons. This study was conducted from 2012 to 2013 in farmland located in the semi-humid area of the Changwu station, Shaanxi, and the results showed that the application of N fertilizer triggered the highest amount of N2O production and effluxes in the various soil layers. With an increase of N fertilizer, N2O effluxes and production significantly increased; the mean variation of 380 kg N ha(-1) treatment was much greater than that of 250 kg N ha(-1) treatment, particularly after fertilization during the maize growing season (MS). N2O concentrations increased within 30 cm and maintained low and stable values. However, N2O fluxes and production decreased with depth (below 30 cm) and then remained low (approximately zero or even negative) at depths of 30-90 cm. The cumulative N2O fluxes in the 0-15 cm soil layer accounted for 99.0% of the total amount in the soil profile, and high fluxes coincided with periods of relatively high production rates. The cumulative production of N2O also remained in step with the cumulative fluxes. In addition, more N fertilizer was applied, greater production occurred in the topsoil. A significantly positive relationship was found between N2O fluxes and mineral N, and a negative relationship was found between the fluxes and the water-filled pore space (WFPS) in the shallow soil. N2O effluxes increased with increasing amounts of N fertilizer, which was primarily due to nitrification on the Loess Plateau. PMID:26556751

  14. The study of metal contamination in urban soils of Hong Kong using a GIS-based approach.

    PubMed

    Li, Xiangdong; Lee, Siu-lan; Wong, Sze-chung; Shi, Wenzhong; Thornton, Iain

    2004-05-01

    The study of regional variations and the anthropogenic contamination by metals of soils is very important for environmental planning and monitoring in urban areas. An extensive survey was conducted in the highly urbanized Kowloon area (46.9 km(2)) of Hong Kong, using a systematic sampling strategy with a sampling density of 3-5 composite soil samples (0-15 cm) per km(2). Geochemical maps of 'total' metals (Cd, Cr, Cu, Ni, Pb and Zn) from strong acid extraction in the surface soils were produced based on geographical information system (GIS) technology. A significant spatial relationship was found for Ni, Cu, Pb and Zn in the soils using a GIS-based analysis, suggesting that these metal contaminants in the soils of the Kowloon area had common sources. Several hot-spot areas of metal contamination were identified from the composite metal geochemical map, mainly in the old industrial and residential areas. A further GIS analysis revealed that road junctions, major roads and industrial buildings were possible sources of heavy metals in the urban soils. The Pb isotope composition of the contaminated soils showed clear anthropogenic origins. PMID:14749075

  15. 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.

  16. 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.

  17. 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.

  18. A field lysimeter study of heavy metal movement down the profile of soils with multiple metal pollution during chelate-enhanced phytoremediation.

    PubMed

    Hu, Ningjing; Luo, Yongming; Wu, Longhua; Song, Jing

    2007-01-01

    The agricultural soils near a copper smelter in southeast China were found to be highly contaminated with Cu, Pb, Zn, and Cd. Metal migration from the soil to groundwater presents an environmental risk that depends on the physicochemical properties of the contaminated soils. Soil solution samples were obtained using lysimeters from a loam soil with multiple metal pollutions over a period of about 1 yr. A field lysimeter study was also conducted to examine the potential use of (S, S')-ethylenediamine-N, N'-disuccinic acid trisodium salt (EDDSNa3) in chelate-enhanced phytoremedation and to evaluate the leaching of heavy metals. The average heavy metal concentrations in the soil solution (without the addition of EDDS) were high (e.g., 0.15 mg Pb L(-1) at a 50-cm depth) compared to the upper limit for protection of groundwater in China, but varied during the sampling period. Cu concentrations were not correlated with pH or dissolved organic carbon (DOC), but Zn and Cd concentrations were related to soil solution pH. EDDS enhanced metal solubility in the soil, but plant metal uptake by Elsholtzia splendens Nakai did not increase accordingly. There may be an increasing risk of groundwater pollution by Cu and the EDDS enhanced phytoremediation technique needs to be carefully applied to minimize this side effect. PMID:18246705

  19. 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.

  20. Initial characterization of processes of soil carbon stabilizaton using forest satnd-level radiocarbon enrichment

    SciTech Connect

    Swanston, Christopher W.; Torn, Margaret S.; Hanson, Paul J; Southon, John R.; Garten Jr, Charles T; Hanlon, Erin M.; Ganio, L.

    2005-01-01

    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 standlevel 14C-labeling originating from a local industrial release. A simple density fractionation scheme separated SOM into interaggregate 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 D14C, was different. In all cases the free LF had the shortest mean residence times. A significant depth by fraction interaction for 14C indicates that the relative importance of aggregation versus organo-mineral interactions for overall C stabilization changes with depth. The rapid incorporation of 14C label into the otherwise depleted DF shows that this organo-mineral fraction comprises highly stable material as well as more recent inputs.

  1. Initial characterizaiton of processes of soil carbon stabilization using forest stand-level radiocarbon enrichment

    SciTech Connect

    Swanston, Christopher W.; Torn, Margaret S.; Hanson, Paul J.; Southon, John R.; Garten, Charles T.; Hanlon, Erin M.; Ganio, Lisa

    2003-12-01

    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 14C-labeling originating from a local industrial release. A simple density fractionation scheme separated SOM into interaggregate 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 percent of the soil by weight, but contained 40 percent of the soil C in the 0 15 cm soil increment. Likewise, the light fractions were less than 1 percent weight of the 15 30 cm increment, but contained more than 35 percent of the soil C. The degree of SOM protection in the fractions, as indicated by D14C, was different. In all cases the free LF had the shortest mean residence times. A significant depth by fraction interaction for 14C indicates that the relative importance of aggregation versus organo-mineral interactions for overall C stabilization changes with depth. The rapid incorporation of 14C label into the otherwise depleted DF shows that this organo-mineral fraction comprises highly stable material as well as more recent inputs.

  2. Uptake of 244Cm, 238Pu and other radionuclides by trees inhabiting a contaminated flood plain.

    PubMed

    Pinder, J E; McLeod, K W; Alberts, J J; Adriano, D C; Corey, J C

    1984-09-01

    The plant uptake of 244Cm, 137Cs, 238Pu and 90Sr was measured for trees in a flood plain forest whose soils were contaminated by aqueous discharges from a nuclear-fuel chemical separations facility. Uptake of the naturally occurring radionuclide 226Ra was also measured. The relative availability of the nuclides was 238Pu less than 244Cm less than 137Cs less than 226Ra less than or equal to 90Sr. The concentration ratios for 238Pu and 244Cm, 3 X 10(-4) and 3.6 X 10(-3), respectively, were similar to those reported for other plant-soil systems. The ratios for 137Cs and 90Sr, 0.11 and 3.9, were similar to those reported for other southeastern soils. However, the ratio for 226Ra, 2.1, was greater than that normally reported. These ratios, which were determined in the field, were generally similar to those reported for greenhouse studies on the same soil.

  3. 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.

  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. PMID:26744135

  5. 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.

  6. Soil characteristics and phosphorus level effect on phosphorus loss in runoff.

    PubMed

    Davis, Randall L; Zhang, Hailin; Schroder, Jackie Lee; Wang, Jim J; Payton, Mark E; Zazulak, Anne

    2005-01-01

    The loss of phosphorus (P) in runoff from agricultural soils may accelerate eutrophication in lakes and streams as well as degrade surface water quality. Limited soil specific data exist on the relationship between runoff P and soil P. This study investigated the relationship between runoff dissolved reactive phosphorus (DRP) and soil P for three Oklahoma benchmark soils: Richfield (fine, smectitic, mesic Aridic Argiustoll), Dennis (fine, mixed, active, thermic Aquic Argiudoll), and Kirkland (fine, mixed, superactive, thermic Udertic Paleustoll) series. These soils were selected to represent the most important agricultural soils in Oklahoma across three major land resource areas. Surface soil (0-15 cm) was collected from three designated locations, treated with diammonium phosphate (18-46-0) to establish a wide range of water-soluble phosphorus (WSP) (3.15-230 mg kg(-1)) and Mehlich-3 phosphorus (M3P) (27.8-925 mg kg(-1)). Amended soils were allowed to reach a steady state 210 d before simulated rainfall (75 mm h(-1)). Runoff was collected for 30 min from bare soil boxes (1.0 x 0.42 m and 5% slope) and analyzed for DRP and total P. Soil samples collected immediately before rainfall simulation were analyzed for the following: M3P, WSP, ammonium oxalate P saturation index (PSI(ox)), water-soluble phosphorus saturation index (PSI(WSP)), and phosphorus saturation index calculated from M3P and phosphorus sorption maxima (P(sat)). The DRP in runoff was highly related (p < 0.001) to M3P for individual soil series (r2 > 0.92). Highly significant relationships (p < 0.001) were found between runoff DRP and soil WSP for the individual soil series (r2 > 0.88). Highly significant relationships (p < 0.001) existed between DRP and different P saturation indexes. Significant differences (p < 0.05) among the slopes of the regressions for the DRP-M3P, DRP-WSP, DRP-PSI(ox), DRP-PSI(WSP), and DRP-P(sat) relationships indicate that the relationships are soil specific and phosphorus

  7. Soil microbial responses to temporal variations of moisture and temperature in a chihuahuan desert grassland.

    PubMed

    Bell, Colin; McIntyre, Nancy; Cox, Stephen; Tissue, David; Zak, John

    2008-07-01

    Global climate change models indicate that storm magnitudes will increase in many areas throughout southwest North America, which could result in up to a 25% increase in seasonal precipitation in the Big Bend region of the Chihuahuan Desert over the next 50 years. Seasonal precipitation is a key limiting factor regulating primary productivity, soil microbial activity, and ecosystem dynamics in arid and semiarid regions. As decomposers, soil microbial communities mediate critical ecosystem processes that ultimately affect the success of all trophic levels, and the activity of these microbial communities is primarily regulated by moisture availability. This research is focused on elucidating soil microbial responses to seasonal and yearly changes in soil moisture, temperature, and selected soil nutrient and edaphic properties in a Sotol Grassland in the Chihuahuan Desert at Big Bend National Park. Soil samples were collected over a 3-year period in March and September (2004-2006) at 0-15 cm soil depth from 12 3 x 3 m community plots. Bacterial and fungal carbon usage (quantified using Biolog 96-well micro-plates) was related to soil moisture patterns (ranging between 3.0 and 14%). In addition to soil moisture, the seasonal and yearly variability of soil bacterial activity was most closely associated with levels of soil organic matter, extractable NH(4)-N, and soil pH. Variability in fungal activity was related to soil temperatures ranging between 13 and 26 degrees C. These findings indicate that changes in soil moisture, coupled with soil temperatures and resource availability, drive the functioning of soil-microbial dynamics in these desert grasslands. Temporal patterns in microbial activity may reflect the differences in the ability of bacteria and fungi to respond to seasonal patterns of moisture and temperature. Bacteria were more able to respond to moisture pulses regardless of temperature, while fungi only responded to moisture pulses during cooler seasons with

  8. Transport of atrazine, 2,4-D, and dicamba through preferential flowpaths in an unsaturated claypan soil near Centralia, Missouri

    NASA Astrophysics Data System (ADS)

    Tindall, James A.; Vencill, William K.

    1995-03-01

    samples in the field showed increases in concentrations of herbicides at depths where laboratory data indicated greater percentages of what appeared to be preferential flowpaths. Concentrations of atrazine, 2,4-D, and dicamba exceeding 0.50, 0.1, and 0.15 μg ml -1 were observed with depth (45-135 cm, 60-125 cm and 60-135 cm) after several months following rainfall events. Preferential flowpaths were a major factor in transport of atrazine, 2,4-D, and dicamba at the site.

  9. 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.

  10. 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. PMID:21814815

  11. 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.

  12. 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

  13. CARBON SEQUESTRATION IN RECLAIMED MINED SOILS OF OHIO

    SciTech Connect

    M. K. Shukla; R. Lal

    2004-01-01

    This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed mine soils (RMS). Experimental sites characterized by distinct age chronosequences of reclaimed minesoil were identified. These sites are owned by Americal Electrical Power and are located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. The sites chosen were: (1) reclaimed without topsoil application (three under forest and three under continuous grass cover), (2) reclaimed with topsoil application (three under forest and three under continuous grass cover) and (3) unmined sites (one under forest and another grass cover). Soil samples were collected from 0 to 15 cm and 15 to 30 cm depths from each of the experimental site under continuous grass and SOC and, total nitrogen (TN) concentration, pH and electrical conductivity (EC) were determined. The results of the study for the quarter (30 September to 31 December, 2003) showed that soil pH was > 5.5 and EC < 4 dS m{sup -1} for all sites and depths and therefore favorable for grass growth. Among the three reclamation treatments, SOC concentration increased from 1.9 g kg{sup -1} for site reclaimed in 2003 (newly reclaimed and at baseline) to 11.64 g kg{sup -1} for site reclaimed in 1987 (a 5-fold increase) to 20.41 g kg{sup -1} for sites reclaimed in 1978 (a 10- fold increase). However, for sites reclaimed without topsoil application, soil pH, EC, SOC and TN concentrations were similar for both depths. The SOC concentrations in reclaimed sites with topsoil application in 0 to 15 cm depth increased from a base value of 0.7 g kg{sup -1} at the rate of 0.76 g kg{sup -1} yr{sup -1}. The high SOC concentration for 0-15 cm layer for site reclaimed in 1978 showed the high carbon sequestration potential upon reclamation and establishment of the grass cover on minesoils.

  14. Effect of tillage practices on soil properties and crop productivity in wheat-mungbean-rice cropping system under subtropical climatic conditions.

    PubMed

    Alam, Md Khairul; Islam, Md Monirul; Salahin, Nazmus; Hasanuzzaman, Mirza

    2014-01-01

    This study was conducted to know cropping cycles required to improve OM status in soil and to investigate the effects of medium-term tillage practices on soil properties and crop yields in Grey Terrace soil of Bangladesh under wheat-mungbean-T. aman cropping system. Four different tillage practices, namely, zero tillage (ZT), minimum tillage (MT), conventional tillage (CT), and deep tillage (DT), were studied in a randomized complete block (RCB) design with four replications. Tillage practices showed positive effects on soil properties and crop yields. After four cropping cycles, the highest OM accumulation, the maximum root mass density (0-15 cm soil depth), and the improved physical and chemical properties were recorded in the conservational tillage practices. Bulk and particle densities were decreased due to tillage practices, having the highest reduction of these properties and the highest increase of porosity and field capacity in zero tillage. The highest total N, P, K, and S in their available forms were recorded in zero tillage. All tillage practices showed similar yield after four years of cropping cycles. Therefore, we conclude that zero tillage with 20% residue retention was found to be suitable for soil health and achieving optimum yield under the cropping system in Grey Terrace soil (Aeric Albaquept). PMID:25197702

  15. Effect of tillage practices on soil properties and crop productivity in wheat-mungbean-rice cropping system under subtropical climatic conditions.

    PubMed

    Alam, Md Khairul; Islam, Md Monirul; Salahin, Nazmus; Hasanuzzaman, Mirza

    2014-01-01

    This study was conducted to know cropping cycles required to improve OM status in soil and to investigate the effects of medium-term tillage practices on soil properties and crop yields in Grey Terrace soil of Bangladesh under wheat-mungbean-T. aman cropping system. Four different tillage practices, namely, zero tillage (ZT), minimum tillage (MT), conventional tillage (CT), and deep tillage (DT), were studied in a randomized complete block (RCB) design with four replications. Tillage practices showed positive effects on soil properties and crop yields. After four cropping cycles, the highest OM accumulation, the maximum root mass density (0-15 cm soil depth), and the improved physical and chemical properties were recorded in the conservational tillage practices. Bulk and particle densities were decreased due to tillage practices, having the highest reduction of these properties and the highest increase of porosity and field capacity in zero tillage. The highest total N, P, K, and S in their available forms were recorded in zero tillage. All tillage practices showed similar yield after four years of cropping cycles. Therefore, we conclude that zero tillage with 20% residue retention was found to be suitable for soil health and achieving optimum yield under the cropping system in Grey Terrace soil (Aeric Albaquept).

  16. Drug Resistance of Enteric Bacteria VI. Introduction of Bacteriophage P1CM into Salmonella typhi and Formation of P1dCM and F-CM Elements

    PubMed Central

    Kondo, Eiko; Mitsuhashi, Susumu

    1966-01-01

    Kondo, Eiko (Gunma University, Maebashi, Japan), and Susumu Mitsuhashi. Drug resistance of enteric bacteria. VI. Introduction of bacteriophage P1CM into Salmonella typhi and formation of P1dCM and F-CM elements. J. Bacteriol. 91:1787–1794. 1966.—Bacteriophage P1CM was introduced into Salmonella typhi by means of both phage infection and conjugation with Escherichia coli F+ lysogenic for the phage. Upon incubation with a P1CM phage lysate, S. typhi and S. abony yield CMr cells which are lysogenic for P1CM, but S. typhimurium LT2 does not. The P1CM phage is adsorbed slightly to S. typhi, but no infectious centers are formed when the phage is plated on this strain. Tests on P1CM-adsorbing capacity of the S. typhi P1CM+ strain and on plaque formation and transduction ability of the recovered phage from this strain indicated that the cell and the phage population did not have any special advantage over the original cell and phage population. Conjugation of S. typhi with E. coli F+ carrying P1CM+ gave three types of S. typhi CMr clones: those which carry the whole P1CM phage, those with the P1dCM element, and those with nontransferable CMr. The second type has the F factor and is sensitive to f phages in spite of its typical behavior, serologically and biochemically, as S. typhi. It can donate the P1dCM and F+ characters to E. coli F− or F−/P1 strains. As a consequence of conjugation with the E. coli F+ strain, the CMr character of the third type of S. typhi, the nontransferable CMr element, acquired conjugational transferability, owing to the formation of the element, F-CM. This element can be transferred to an E. coli F− strain at a very high frequency (ca. 100). Both the F and CMr determinants are jointly transduced with P1 phage and are jointly eliminated by acridine dye treatment. PMID:5327907

  17. 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.

  18. 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).

  19. High temperature performance of surface-treated Li{sub 1.1}(Ni{sub 0.15}Co{sub 0.1}Mn{sub 0.55})O{sub 1.95} layered oxide.

    SciTech Connect

    Deng, H.; Belharouak, I.; Yoon, C. S.; Sun, Y.-K.; Amine, K.

    2010-07-29

    The electrochemical performance of pristine and AlF{sub 3}-coated Li{sub 1.1}Ni{sub 0.15}Co{sub 0.1}Mn{sub 0.55}O{sub 1.95} cathodes is reported for cells cycled at 25 and 55 C. In a half-cell configuration, a nanolayer coating of AlF{sub 3} on the Li{sub 1.1}Ni{sub 0.15}Co{sub 0.1}Mn{sub 0.55}O{sub 1.95} stabilizes the capacity on cycling. However, in cell tests with metallic lithium anodes, the initial coulombic efficiency decreased slightly at both 25 and 55 C for AlF{sub 3}-coated Li{sub 1.1}Ni{sub 0.15}Co{sub 0.1}Mn{sub 0.55}O{sub 1.95} in comparison to the pristine material. For cells constructed with graphite instead of lithium anodes, the capacity stability improved with cycling for the coated cathode materials. Transition-metal dissolution was more pronounced for the AlF{sub 3}-coated sample when stored at 55 C in electrolytes. For both the pristine and AlF{sub 3}-coated samples, there was no extra capacity loss due to the elevated temperature. Around 10% capacity gain of the cathode materials at elevated temperature is assumed to be due to improved thermodynamic activation.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  5. 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.

  6. 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.

  7. 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

  8. A field study to assess the degradation and transport of diuron and its metabolites in a calcareous soil.

    PubMed

    Gooddy, Daren C; Chilton, P John; Harrison, Ian

    2002-10-01

    An experimental plot has been established on a calcareous soil in southern England to investigate the fate and transport of diuron (N'-[3,4-dichlorophenyl]-N,N-dimethylurea), a commonly used phenylurea herbicide. An agricultural grade of diuron was applied to the soil surface at a rate of 6.7 kg/ha along with a potassium bromide conservative tracer applied at 200 kg/ha, in early January, 2001. Hand augured samples were taken at regular intervals over the next 50 days, with samples collected down to 54 cm. Porewaters were extracted from the soil cores by using high speed centrifugation and the supernatant fluids were retained for analysis by HPLC, for diuron and three of its metabolites, N'-[3,4-dichlorophenyl]-N,N-methylurea (DCPMU), N'-3,4-dichlorophenylurea (DCPU) and 3,4-dichloroaniline (DCA). The centrifuged soil was retained and then extracted with methanol prior to HPLC analysis for the same suite of phenylureas. A mass balance approach showed large variations in diuron distribution, but on average accounted for 104% of the diuron applied. Concentrations of diuron and its metabolites were roughly five times higher in the soil than in the soil porewaters. After 50 days, metabolites comprised 10% of the total diuron present in the porewater and 20% of the total diuron sorbed to the soil matrix. After 36 days, a large pulse of diuron and DCPMU appeared in the porewaters and soil matrix at a depth of 54 cm, travelling an average of 0.15 cm/day faster than Br. A preferential route for diuron transport is suggested. There is evidence to suggest that degradation occurs at depth as well as at the soil surface. Metabolites generally appear to move more slowly than the parent compound. All metabolites were encountered, but interpreting transport and degradation processes simultaneously proved beyond the scope of the study. Diuron was detected once in a shallow (5 m) observation well, situated on the experimental plot. High concentrations of diuron and metabolites were

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    Hu, Mingzhe; Xiong, Gang; Ding, Zhao

    2016-04-01

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

  14. Structural and electrical properties of grain boundaries in Ce 0.85Gd 0.15O 1.925 solid electrolyte modified by addition of transition metal ions

    NASA Astrophysics Data System (ADS)

    Zając, Wojciech; Suescun, Leopoldo; Świerczek, Konrad; Molenda, Janina

    In this work we present studies on applicability of transition metal additives as sintering and electrical conductivity aids for cerium gadolinium oxide electrolyte. The nanosized Ce 0.85Gd 0.15O 1.925 powder obtained by coprecipitation method was modified with Cr 3+, Fe 3+, Ni 2+ or Cu 2+ ions. Using high-intensity high-resolution X-ray powder diffraction data we have determined that Cr, Fe and Ni ions do not incorporate into the cerium gadolinium oxide surface or bulk when sintered at 1300 °C, but react with Gd ions to form Cr 0.9Gd 0.1O, GdFeO 3 and GdNiO 3 phases, while Cu incorporates in the material up to 0.7 mol% with a significant fraction of remaining material showing poorly crystalline CuO phase. The nanosized Ce 0.85Gd 0.15O 1.925 material shows already improved sintering properties than previous reports but full sintering is not achieved below 1300 °C, however Cr, Fe and mainly Cu impregnation allows full sintering at 1300 °C. 0.5 mol% Ni impregnated material sintered at 1500 °C shows enhanced grain boundary conductivity that probably indicates that Ni incorporates into Ce 0.84Gd 0.15O 1.925 above 1300 °C. The global results indicate, however, that optimization of ceria microstructure is at least of equal importance for sinterability and grain boundary conductivity than impregnation of the material with transition metal ions.

  15. In Situ Carbon-Doped Mo(Se0.85 S0.15 )2 Hierarchical Nanotubes as Stable Anodes for High-Performance Sodium-Ion Batteries.

    PubMed

    Shi, Zheng-Tian; Kang, Wenpei; Xu, Jun; Sun, Lian-Ling; Wu, Chunyan; Wang, Li; Yu, Yong-Qiang; Yu, Denis Y W; Zhang, Wenjun; Lee, Chun-Sing

    2015-11-11

    Sodium-ion batteries (SIBs) are promising energy storage devices, but suffer from poor cycling stability and low rate capability. In this work, carbon doped Mo(Se0.85 S0.15 )2 (i.e., Mo(Se0.85 S0.15 )2 :C) hierarchical nanotubes have been synthesized for the first time and serve as a robust and high-performance anode material. The hierarchical nanotubes with diameters of 300 nm and wall thicknesses of 50 nm consist of numerous 2D layered nanosheets, and can act as a robust host for sodiation/desodiation cycling. The Mo(Se0.85 S0.15 )2 :C hierarchical nanotubes deliver a discharge capacity of 360 mAh g(-1) at a high current density of 2000 mA g(-1) and keep a 81.8% capacity retention compared to that at a current density of 50 mA g(-1) , showing superior rate capability. Comparing with the second cycle discharge capacities, the nanotube anode can maintain capacities of 102.2%, 101.9%, and 97.8% after 100 cycles at current densities of 200, 500, and 1000 mA g(-1) , respectively. This work demonstrates the best cycling performance and high-rate sodium storage capabilities of MoSe2 for SIBs to date. The hollow interior, hierarchical organization, layered structure, and carbon doping are beneficial for fast Na(+) -ion and electron kinetics and are responsible for the stable cycling performance and high rate capabilities.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  17. 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.

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

    SciTech Connect

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

    2014-09-15

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

  19. 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.

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

    SciTech Connect

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

    2015-06-24

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

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

    SciTech Connect

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

    2012-10-15

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

  2. Two-Fermi-Surface Superconducting State and a Nodal d-Wave Energy Gap of the Electron-Doped Sm1.85Ce0.15CuO4-δ Cuprate Superconductor

    NASA Astrophysics Data System (ADS)

    Santander-Syro, A. F.; Ikeda, M.; Yoshida, T.; Fujimori, A.; Ishizaka, K.; Okawa, M.; Shin, S.; Greene, R. L.; Bontemps, N.

    2011-05-01

    We report on laser-excited angle-resolved photoemission spectroscopy in the electron-doped cuprate Sm1.85Ce0.15CuO4-δ. The data show the existence of a nodal hole-pocket Fermi surface both in the normal and superconducting states. We prove that its origin is long-range antiferromagnetism by an analysis of the coherence factors in the main and folded bands. This coexistence of long-range antiferrmagnetism and superconductivity implies that electron-doped cuprates are two-Fermi-surface superconductors. The measured superconducting gap in the nodal hole pocket is compatible with a d-wave symmetry.

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

    NASA Astrophysics Data System (ADS)

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

    1997-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Requena, Sebastian; Williams, Scott

    2011-03-01

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

  5. 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

  6. [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.

  7. [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. PMID:27363164

  8. Maize (Zea mays L.) performance in organically amended mine site soils.

    PubMed

    Oladipo, Oluwatosin Gbemisola; Olayinka, Akinyemi; Awotoye, Olusegun Olufemi

    2016-10-01

    Organic amendments play an important role in the eco-friendly remediation of degraded mine site soils. This study investigated the quality (essential nutrients and heavy metal content) of maize grown on organically amended soils from three active mines in Nigeria. Soil samples were collected randomly at 0-15 cm depth, air-dried and sieved. Five kg of soil were amended with poultry manure and sawdust (poultry manure only, sawdust only, poultry manure-sawdust mixtures in 3:1, 2:1 and 1:1 ratios) at 10 g kg(-1). Maize (Zea mays L.) seeds were planted and watered for two consecutive periods of 8 weeks, with the control and treatment experiments set up in the screenhouse in quadruples. Harvested tissues were weighed, dried, ground and digested. Chemical properties were determined using standard methods while atomic absorption spectrophotometry was used to determine total metal concentrations (Ca, Mg, Fe, Zn, Pb, Cd and Cu). ANOVA was used to test for significant differences among treatment groups in the various parameters. Application of poultry manure-sawdust mixtures significantly (p < 0.05) enhanced tissue dry matter yield, as well as N, P, K, and Na contents while Zn, Cd, Cu and Pb were immobilized to approximately 50-100%. Treatment with sawdust alone reduced tissue nutrient content resulting in depressed plant yield while poultry manure only though enhanced crop yield, contained higher heavy metal contents. Soil amendments comprised of poultry manure-sawdust mixtures can be effective remediation strategy for mine site soils, as these organic materials help replenish soil nutrients, immobilize heavy metals, and enhance food productivity. PMID:27415409

  9. 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.

  10. 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.

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

    ERIC Educational Resources Information Center

    Allen, Louisa

    2009-01-01

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

  12. 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.

  13. 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.

  14. New approach to measure soil particulate organic matter in intact samples using X-ray computed micro-tomography

    NASA Astrophysics Data System (ADS)

    Kravchenko, Alexandra; Negassa, Wakene; Guber, Andrey; Schmidt, Sonja

    2014-05-01

    Particulate soil organic matter (POM) is biologically and chemically active fraction of soil organic matter. It is a source of many agricultural and ecological benefits, among which are POM's contribution to C sequestration. Most of conventional research methods for studying organic matter dynamics involve measurements conducted on pre-processed i.e., ground and sieved soil samples. Unfortunately, grinding and sieving completely destroys soil structure, the component crucial for soil functioning and C protection. Importance of a better understanding of the role of soil structure and of the physical protection that it provides to soil C cannot be overstated; and analysis of quantities, characteristics, and decomposition rates of POM in soil samples with intact structure is among the key elements of gaining such understanding. However, a marked difficulty hindering the progress in such analyses is a lack of tools for identification and quantitative analysis of POM in intact soil samples. Recent advancement in applications of X-ray computed micro-tomography (μ-CT) to soil science has given an opportunity to conduct such analyses. The objective of the current study is to develop a procedure for identification and quantitative characterization of POM within intact soil samples using X-ray μ-CT images and to test performance of the proposed procedure on a set of multiple intact soil macro-aggregates. We used 16 4-6 mm soil aggregates collected at 0-15 cm depth from a Typic Hapludalf soil at multiple field sites with diverse agricultural management history. The aggregates have been scanned at SIMBIOS Centre, Dundee, Scotland at 10 micron resolution. POM was determined from the aggregate images using the developed procedure. The procedure was based on combining image pre-processing steps with discriminant analysis classification. The first component of the procedure consisted of image pre-processing steps based on the range of gray values (GV) along with shape and size

  15. 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

  16. 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.

  17. Enhanced magnetic response in single-phase Bi0.80La0.15A0.05FeO3-δ (A=Ca, Sr, Ba) ceramics

    NASA Astrophysics Data System (ADS)

    Sharma, Poorva; Kumar, Ashwini; Varshney, Dinesh

    2015-10-01

    Single phase Bi0.80La0.15A0.05FeO3-δ (A=Ca, Sr, Ba) dense ceramics were synthesized via solid state reaction method. Structural studies through X-ray diffraction shows that all prepared ceramics crystallized in a rhombohedrally (R 3 barC)distorted BiFeO3 structure with compressive lattice distortion induced by the rare earth (La3+) ion and divalent co-doping at the Bi-site for the Raman study. Scanning electron micrograph of the compounds showed the uniform distribution of grains on the sample surface with high density. A large ferromagnetic hysteresis loop is observed for La/Ba co-doped BiFeO3 as compared with BiFeO3 prepared under similar conditions, with saturation magnetization of 6.85 emu/g and remnant magnetization of 2.72 emu/ g at 300 K. Clear ferromagnetic ground state was observed in Bi0.80La0.15Ba0.05FeO3 and weak ferromagnetism in BLCFO and BLSFO samples. Dielectric constant and dielectric loss were found to decrease with increase in frequency for all the compounds. These improved properties of La/Ba co-doped BFO demonstrate the possibility of enhancing the magnetic applicability and makes very promising for industrial applications such as new devices in information storage.

  18. 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.

  19. Electronic structural changes of the electrochemically Li-ion deintercalated LiNi 0.8Co 0.15Al 0.05O 2 cathode material investigated by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Yoon, Won-Sub; Chung, Kyung Yoon; McBreen, James; Fischer, Daniel A.; Yang, Xiao-Qing

    In situ hard X-ray absorption spectroscopy (XAS) at metal K-edges and soft XAS at O K-edge and metal L-edges have been carried out during the first charging process for the layered Li 1- xNi 0.8Co 0.15Al 0.05O 2 cathode material. The metal K-edge XAS results show that the major charge compensation at the metal site during Li-ion deintercalation is achieved by the oxidation of Ni ions, while the cobalt ions remain mostly unchanged in the Co 3+ state. Ni L II,III-edge and O K-edge XAS results in both the fluorescence yield (FY) and partial electron yield (PEY) modes show that substantial amount of Ni ions at the surface of LiNi 0.8Co 0.15Al 0.05O 2 powders exist as Ni 2+, whereas most of Ni ions in the bulk are in the form of Ni 3+. Therefore, if the PEY mode, which is a surface-sensitive technique, is used alone, the interpretation of the results is limited to the surface structures only. In order to get the full picture of both the surface and the bulk, the FY mode and PEY mode should be used simultaneously.

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

    SciTech Connect

    Kostecki, Robert; McLarnon, Frank

    2003-09-01

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

  1. Exhibition of structural flexibility of the infinite layer framework of the prototype compound Ca{sub 0.85}Sr{sub 0.15}CuO{sub 2} prepared under ambient conditions

    SciTech Connect

    Kiruthika, G.V.M. . E-mail: gvmk@tifr.res.in; Varadaraju, U.V.

    2005-09-01

    The infinite layer compound Ca{sub 0.85}Sr{sub 0.15}CuO{sub 2} has been synthesized by the sol-gel technique using the acetate gel route. The compound is found to be single-phasic as evidenced from the powder X-ray and electron diffraction measurements. EDAX analysis confirms the presence of homogenous stoichiometric phase pertaining to the composition Ca{sub 0.85}Sr{sub 0.15}CuO{sub 2}. High-resolution electron microscopy (HREM) studies reveal interesting defects in the infinite layer frame work of the system. Apart from the usual strain and shear induced defects observed in the lattice, which is common among the perovskite compounds, the main finding is the defect along [0 1 0], occurring due to the intercalation of extra AO layer in the CuO{sub 2} plane. Such a defect is accommodated in the lattice by the increase in the interplanar distance (which is basically the c-axis parameter) from 3.2 to 3.4 A in the defective layer. This implies the formation of square pyramidal oxygen co-ordination of copper at the defect site.

  2. 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.

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

    PubMed

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

    1985-07-01

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

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

    PubMed

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

    2014-07-01

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

  5. 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.

  6. 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. PMID:23422041

  7. Comparison of elemental contents in earthworm cast and soil from a mercury-contaminated site (Idrija area, Slovenia).

    PubMed

    Teršič, Tamara; Gosar, Mateja

    2012-07-15

    The aim of this paper was to test the new sampling media-earthworm casts in a highly contaminated area. The investigation was carried out at the ancient Hg ore roasting site Pšenk in the surroundings of Idrija, where extremely high Hg contents in soils and SOM were determined in previous investigations. 32 earthworm cast samples were collected in the research grid 30 × 30 m in order to compare the Hg contents and spatial distribution in earthworm casts to the values and distributions in SOM and soil (0-15 cm). Extremely elevated Hg concentrations were determined in earthworm casts from the studied area ranging from 5.4 to 4330 mg/kg with the median of 31 mg/kg. The Hg values in casts are somewhat lower than in soil (6.3-8600 mg/kg) and slightly higher compared to soil organic matter (SOM) (1.5-4200 mg/kg). Strong correlation (r²=0.75) between Hg contents in casts and soil was found, while correlation between casts and SOM was positive but weaker (r²=0.35). Spatial distribution of Hg in earthworm casts show the highest concentrations in the central part of investigated area, similar to the distribution in soil. Hg contents rapidly decrease from the center toward the margins of the studied area, where they reach values of less than 50mg/kg. It was shown that Hg contents and dispersion in casts are comparable to those in soil, which indicates that at investigated area soil contamination is strongly reflected in contamination of earthworm casts.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Spectral reflectance properties of carbonaceous chondrites: 2. CM chondrites

    NASA Astrophysics Data System (ADS)

    Cloutis, E. A.; Hudon, P.; Hiroi, T.; Gaffey, M. J.; Mann, P.

    2011-11-01

    We have examined the spectral reflectance properties and available modal mineralogies of 39 CM carbonaceous chondrites to determine their range of spectral variability and to diagnose their spectral features. We have also reviewed the published literature on CM mineralogy and subclassification, surveyed the published spectral literature and added new measurements of CM chondrites and relevant end members and mineral mixtures, and measured 11 parameters and searched pair-wise for correlations between all quantities. CM spectra are characterized by overall slopes that can range from modestly blue-sloped to red-sloped, with brighter spectra being generally more red-sloped. Spectral slopes, as measured by the 2.4:0.56 μm and 2.4 μm:visible region peak reflectance ratios, range from 0.90 to 2.32, and 0.81 to 2.24, respectively, with values <1 indicating blue-sloped spectra. Matrix-enriched CM spectra can be even more blue-sloped than bulk samples, with ratios as low as 0.85. There is no apparent correlation between spectral slope and grain size for CM chondrite spectra - both fine-grained powders and chips can exhibit blue-sloped spectra. Maximum reflectance across the 0.3-2.5 μm interval ranges from 2.9% to 20.0%, and from 2.8% to 14.0% at 0.56 μm. Matrix-enriched CM spectra can be darker than bulk samples, with maximum reflectance as low as 2.1%. CM spectra exhibit nearly ubiquitous absorption bands near 0.7, 0.9, and 1.1 μm, with depths up to 12%, and, less commonly, absorption bands in other wavelength regions (e.g., 0.4-0.5, 0.65, 2.2 μm). The depths of the 0.7, 0.9, and 1.1 μm absorption features vary largely in tandem, suggesting a single cause, specifically serpentine-group phyllosilicates. The generally high Fe content, high phyllosilicate abundance relative to mafic silicates, and dual Fe valence state in CM phyllosilicates, all suggest that the phyllosilicates will exhibit strong absorption bands in the 0.7 μm region (due to Fe 3+-Fe 2+ charge

  13. [Characteristics of carbon sequestration and apparent stability of new sequestered carbon in forested torrid red soil at dry-hot valley].

    PubMed

    Tang, Guo-Yong; Li, Kun; Sun, Yong-Yu; Zhang, Chun-Hua

    2012-02-01

    Great concerns about potential for carbon (C) sequestration in forested soil and the stability of the sequestered C have been exerted under the background of global climate change. Organic C density in soil and in soil physical and biochemical fractions at various stages (1991, 1997, 2003 and 2010) in Acacia auriculiformis stand afforested in 1991 were investigated at Dry-Hot Valley via density fractionation and acid hydrolysis. The results showed that organic C density at surface (0-15 cm) and subsurface (15-30 cm) soil layers was 1.40 kg x m(-2) and 0.99 kg x m(-2) after 19 years of afforestation, respectively. The annual C sequestration rates of surface and subsurface soil layers were 37.89 g x (m2 x a)(-1) and 16.84 g x (m2 x a)(-1) during 1991-2010, respectively, and the sequestration was accelerating. The ratio of organic C in heavy fraction to in surface soil was 71.44% in 2003, which was significantly higher than that in 2010 (67.99%). The recalcitrant carbon index (I(RC)) in light fraction was significantly higher than that in heavy fraction at surface or subsurface layers in 2003, but both decreased with aging of plantation, especially I(RC) in light fraction. Approximately 57% - 70% of new sequestered C was protected by physical mechanism and 33-49 percent was biochemical recalcitrant C during the stage from 12 to 19 years after afforestation. The results reveal that forested torrid red soil at Dry-Hot Valley may have a considerable capability of C sequestration. The biochemical stability of physically protected C is lower than the unprotected. Both the stability, however, decreases with the plantation age.

  14. CmWRKY15 Facilitates Alternaria tenuissima Infection of Chrysanthemum.

    PubMed

    Fan, Qingqing; Song, Aiping; Xin, Jingjing; Chen, Sumei; Jiang, Jiafu; Wang, Yinjie; Li, Xiran; Chen, Fadi

    2015-01-01

    Abscisic acid (ABA) has an important role in the responses of plants to pathogens due to its ability to induce stomatal closure and interact with salicylic acid (SA) and jasmonic acid (JA). WRKY transcription factors serve as antagonistic or synergistic regulators in the response of plants to a variety of pathogens. Here, we demonstrated that CmWRKY15, a group IIa WRKY family member, was not transcriptionally activated in yeast cells. Subcellular localization experiments in which onion epidermal cells were transiently transfected with CmWRKY15 indicated that CmWRKY15 localized to the nucleus in vivo. The expression of CmWRKY15 could be markedly induced by the presence of Alternaria tenuissima inoculum in chrysanthemum. Furthermore, the disease severity index (DSI) data of CmWRKY15-overexpressing plants indicated that CmWRKY15 overexpression enhanced the susceptibility of chrysanthemum to A. tenuissima infection compared to controls. To illustrate the mechanisms by which CmWRKY15 regulates the response to A. tenuissima inoculation, the expression levels of ABA-responsive and ABA signaling genes, such as ABF4, ABI4, ABI5, MYB2, RAB18, DREB1A, DREB2A, PYL2, PP2C, RCAR1, SnRK2.2, SnRK2.3, NCED3A, NCED3B, GTG1, AKT1, AKT2, KAT1, KAT2, and KC1were compared between transgenic plants and controls. In summary, our data suggest that CmWRKY15 might facilitate A. tenuissima infection by antagonistically regulating the expression of ABA-responsive genes and genes involved in ABA signaling, either directly or indirectly. PMID:26600125

  15. New results on the ternary fission of 243Cm

    NASA Astrophysics Data System (ADS)

    Heyse, J.; Wagemans, C.; Vermote, S.; Serot, O.; Geltenbort, P.; Soldner, T.; Van Gils, J.

    2005-11-01

    Ternary fission is an important source of He and tritium gas in nuclear reactors and used fuel elements. Therefore a systematic study of the ternary fission yields for 4He and tritons (t) is being performed. In recent years the influence of the excitation energy of the fissioning nucleus on the triton emission probability (t/B) has been investigated for different Cm and Cf isotopes. In this paper we report on new results on the neutron induced fission of 243Cm.

  16. CmWRKY15 Facilitates Alternaria tenuissima Infection of Chrysanthemum

    PubMed Central

    Fan, Qingqing; Song, Aiping; Xin, Jingjing; Chen, Sumei; Jiang, Jiafu; Wang, Yinjie; Li, Xiran; Chen, Fadi

    2015-01-01

    Abscisic acid (ABA) has an important role in the responses of plants to pathogens due to its ability to induce stomatal closure and interact with salicylic acid (SA) and jasmonic acid (JA). WRKY transcription factors serve as antagonistic or synergistic regulators in the response of plants to a variety of pathogens. Here, we demonstrated that CmWRKY15, a group IIa WRKY family member, was not transcriptionally activated in yeast cells. Subcellular localization experiments in which onion epidermal cells were transiently transfected with CmWRKY15 indicated that CmWRKY15 localized to the nucleus in vivo. The expression of CmWRKY15 could be markedly induced by the presence of Alternaria tenuissima inoculum in chrysanthemum. Furthermore, the disease severity index (DSI) data of CmWRKY15-overexpressing plants indicated that CmWRKY15 overexpression enhanced the susceptibility of chrysanthemum to A. tenuissima infection compared to controls. To illustrate the mechanisms by which CmWRKY15 regulates the response to A. tenuissima inoculation, the expression levels of ABA-responsive and ABA signaling genes, such as ABF4, ABI4, ABI5, MYB2, RAB18, DREB1A, DREB2A, PYL2, PP2C, RCAR1, SnRK2.2, SnRK2.3, NCED3A, NCED3B, GTG1, AKT1, AKT2, KAT1, KAT2, and KC1were compared between transgenic plants and controls. In summary, our data suggest that CmWRKY15 might facilitate A. tenuissima infection by antagonistically regulating the expression of ABA-responsive genes and genes involved in ABA signaling, either directly or indirectly. PMID:26600125

  17. Soil carbon dynamics

    NASA Astrophysics Data System (ADS)

    Trumbore, Susan; Barbosa de Camargo, Plínio

    The amount of organic carbon (C) stored in the upper meter of mineral soils in the Amazon Basin (˜40 Pg C) represents ˜3% of the estimated global store of soil carbon. Adding surface detrital C stocks and soil carbon deeper than 1 m can as much as quadruple this estimate. The potential for Amazon soil carbon to respond to changes in land use, climate, or atmospheric composition depends on the form and dynamics of soil carbon. Much (˜30% in the top ˜10 cm but >85% in soils to 1 m depth) of the carbon in mineral soils of the Oxisols and Ultisols that are the predominant soil types in the Amazon Basin is in forms that are strongly stabilized, with mean ages of centuries to thousands of years. Measurable changes in soil C stocks that accompany land use/land cover change occur in the upper meter of soil, although the presence of deep roots in forests systems drives an active C cycle at depths >1 m. Credible estimates of the potential for changes in Amazon soil C stocks with future land use and climate change are much smaller than predictions of aboveground biomass change. Soil organic matter influences fertility and other key soil properties, and thus is important independent of its role in the global C cycle. Most work on C dynamics is limited to upland soils, and more is needed to investigate C dynamics in poorly drained soils. Work is also needed to relate cycles of C with water, N, P, and other elements.

  18. 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.

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

    SciTech Connect

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

    2008-08-04

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

  20. Lorentz microscopy and small-angle electron diffraction study of magnetic textures in L a1 -xS rxMn O3 (0.15

    NASA Astrophysics Data System (ADS)

    Kotani, A.; Nakajima, H.; Harada, K.; Ishii, Y.; Mori, S.

    2016-07-01

    Magnetic textures in the ferromagnetic phases of L a1 -xS rxMn O3 for 0.15

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

    SciTech Connect

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

    2014-06-01

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

  2. Study of the electronic and magnetic properties as a function of isoelectronic substitution in SmFe(1-x)RuxAsO0.85F0.15.

    PubMed

    Simonelli, L; Al-Zein, A; Moretti Sala, M; Joseph, B; Iadecola, A; Bendele, M; Martinelli, A; Palenzona, A; Putti, M; Monaco, G

    2014-02-12

    We have studied the electronic and magnetic properties of SmFe(1-x)RuxAsO0.85F0.15 (x = 0, 0.05, 0.25, 0.33, 0.5) by high-resolution x-ray absorption and x-ray emission spectroscopy. The local Fe magnetic moment (μ) tends to decrease for a small Ru substitution, but it shows a clear increase with further substitution. It appears that impurity scattering prevails in reducing the μ with small Ru substitution due to an extended Ru d-band. A nanoscale phase separation, that decouples the FeAs layers from the spacer layers, drives the increase of μ at higher Ru substitution. The results provide important information on nanoscale phase separation due to isoelectronic substitution in the active layers of iron-based 1111-superconductors and its effect on the local magnetic properties.

  3. 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.

  4. Reverse Monte Carlo analysis of the local order in liquid Ge{sub 0.15}Te{sub 0.85} alloys combining neutron scattering and x-ray absorption spectroscopy

    SciTech Connect

    Coulet, Marie-Vanessa; Testemale, Denis; Hazemann, Jean-Louis; Gaspard, Jean-Pierre; Bichara, Christophe

    2005-11-01

    The structure of liquid Ge{sub 0.15}Te{sub 0.85} alloys that exhibit a density anomaly between 633 K and 733 K at ambient pressure was investigated using x-ray absorption spectroscopy at the Ge K edge. Using a reverse Monte Carlo method to combine the present results with neutron scattering data, we show that the volume contraction is associated with an increase of the first neighbor coordination number around both Ge and Te by about one atom. The coordination number of Ge increases from 3{+-}0.3 to 4.1{+-}0.3. These results support an interpretation of the density anomaly in terms of the same Peierls-like distortion mechanism acting in the liquid state and in the neighboring (pure Te and GeTe compound) phases.

  5. Study of the anisotropic dielectric behavior of Rb1-x(NH4)xH2PO4 (x=0.15 and 0.17) mixed crystals

    NASA Astrophysics Data System (ADS)

    Noh, Keum Hwan; Kwun, Sook-Il; Yoon, Jong-Gul

    2000-07-01

    The complex dielectric constants and polarization of the mixed crystals of Rb1-x(NH4)xH2PO4 (RADP) with x=0.15 and 0.17 have been measured along the tetragonal a and c axes as a function of temperature. Phase coexistence of ferroelectric order and proton glass in RADP can be confirmed from a dielectric dispersion distinguished from the ferroelectric domain wall freezing at low temperature. The dielectric dispersion, which was ascribed to the proton glass state, occurred at much lower temperatures compared to pure proton glass composition. The detection of depolarization after field-cooling or zero-field cooling the sample, showed that the ferroelectric domain and polarization were retained in the glass freezing process. The result is qualitatively consistent with the expectation of the mean-field model in the presence of macroscopic polarization. The phase coexistence may be a common feature of KH2PO4 family mixed crystals.

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

    SciTech Connect

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

    2014-07-21

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

  7. The role of the hybridization between Mn 3d and O 2p orbitals in the existence of the Griffiths phase in La0.85Ca0.15MnO3.

    PubMed

    Zhang, Hong-guang; Shi, Jiang-jian; Li, Yong-tao; Dong, Xue-guang; Ge, Xiao-peng; Liu, Hao; Hou, Qing-teng; Li, Qi; Tang, Yan-kun

    2014-04-01

    Favourable conditions for the existence of the Griffiths phase in the La0.85Ca0.15MnO3 compound are experimentally investigated in terms of electronic and lattice structure by temperature-dependent x-ray absorption spectroscopy, valence band photoemission spectroscopy, and x-ray diffraction experiments. The chemical shifts of Mn L-edge and O K-edge x-ray absorption lines in the Griffiths phase are understood to be related to the hybridization between Mn 3d and O 2p states instead of the variation of Mn valence states. Valence band spectra also indicate that the hybridization of O 2p with Mn 3d is enhanced in the Griffiths phase. From a 2D diluted Ising ferromagnet model, this hybridization between Mn 3d and O 2p orbitals surely enhances the Griffiths phase feature. PMID:24637382

  8. 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.

  9. 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

  10. 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

  11. Effect of inorganic fertilizer and farmyard manure on soil physical properties, root distribution, and water-use efficiency of soybean in Vertisols of central India.

    PubMed

    Hati, K M; Mandal, K G; Misra, A K; Ghosh, P K; Bandyopadhyay, K K

    2006-11-01

    A field experiment was conducted on a Vertisol for three consecutive years (1998-2000) to study the effects of combined use of inorganic fertilizer (NPK) and organic manure (farmyard manure) on soil physical properties, water-use efficiency, root growth and yield of soybean [Glycine max (L.) Merr.] in a soybean-mustard cropping system. Application of 10 Mg farmyard manure and recommended NPK (NPK+FYM) to soybean for three consecutive years improved the organic carbon content of the surface (0-15 cm) soil from an initial value of 4.4 g kg(-1) to 6.2 g kg(-1) and also increased seed yield and water-use efficiency by 103% and 76%, respectively, over the control. The surface (0-15 cm) soil of the plots receiving both farmyard manure and recommended NPK had larger mean weight diameter (0.50 mm) and a higher percentage of water stable aggregates (55%) than both the inorganically fertilized (NPK) (0.44 mm and 49%) and unfertilized control plots (0.41 mm and 45.4%). The saturated hydraulic conductivity (13.32 x 10(-6) m s(-1)) of the NPK+FYM treatment of the 0-7.5 cm depth was also significantly greater than that of the NPK (10.53 x 10(-6) m s(-1)) and control (8.61 x 10(-6) m s(-1)) treatments. The lowest bulk density (1.18 Mg m(-3)) in the 0-7.5 cm layer was recorded in NPK+FYM whereas it was highest in the control plots (1.30 Mg m(-3)). However, at sub-surface (22.5-30 cm) layer, fertilizer and manure application had little effect on bulk density and saturated hydraulic conductivity. Root length density (RLD) up to the 30 cm depth was highest in the NPK+FYM plots and it was 31.9% and 70.5% more than NPK and control plots. The RLD showed a significant and negative correlation (r=-0.88( * *)) with the penetration resistance. PMID:16289791

  12. Effect of inorganic fertilizer and farmyard manure on soil physical properties, root distribution, and water-use efficiency of soybean in Vertisols of central India.

    PubMed

    Hati, K M; Mandal, K G; Misra, A K; Ghosh, P K; Bandyopadhyay, K K

    2006-11-01

    A field experiment was conducted on a Vertisol for three consecutive years (1998-2000) to study the effects of combined use of inorganic fertilizer (NPK) and organic manure (farmyard manure) on soil physical properties, water-use efficiency, root growth and yield of soybean [Glycine max (L.) Merr.] in a soybean-mustard cropping system. Application of 10 Mg farmyard manure and recommended NPK (NPK+FYM) to soybean for three consecutive years improved the organic carbon content of the surface (0-15 cm) soil from an initial value of 4.4 g kg(-1) to 6.2 g kg(-1) and also increased seed yield and water-use efficiency by 103% and 76%, respectively, over the control. The surface (0-15 cm) soil of the plots receiving both farmyard manure and recommended NPK had larger mean weight diameter (0.50 mm) and a higher percentage of water stable aggregates (55%) than both the inorganically fertilized (NPK) (0.44 mm and 49%) and unfertilized control plots (0.41 mm and 45.4%). The saturated hydraulic conductivity (13.32 x 10(-6) m s(-1)) of the NPK+FYM treatment of the 0-7.5 cm depth was also significantly greater than that of the NPK (10.53 x 10(-6) m s(-1)) and control (8.61 x 10(-6) m s(-1)) treatments. The lowest bulk density (1.18 Mg m(-3)) in the 0-7.5 cm layer was recorded in NPK+FYM whereas it was highest in the control plots (1.30 Mg m(-3)). However, at sub-surface (22.5-30 cm) layer, fertilizer and manure application had little effect on bulk density and saturated hydraulic conductivity. Root length density (RLD) up to the 30 cm depth was highest in the NPK+FYM plots and it was 31.9% and 70.5% more than NPK and control plots. The RLD showed a significant and negative correlation (r=-0.88( * *)) with the penetration resistance.

  13. Characteristics, genesis and classification of a basin peat soil under negative human impact in Turkey

    NASA Astrophysics Data System (ADS)

    Dengiz, Orhan; Ozaytekin, H. Huseyin; Cayci, Gokhan; Baran, Abdullah

    2009-01-01

    The objective of this research was to investigate the morphology, genesis and classification of organic soils formed on depression and flat land around Lake Yenicaga, west-central Turkey. Formation of the area has been influenced by tectonic and karst processes. This peatland is important in this area due to its extensive use as a horticultural plant growth medium resulting from positive physical and chemical properties. Organic soils in the study area were formed in nutrient-rich conditions and it is classified as typical basin peat. Four representative pedons were excavated in the study area based on extensive observations performed with random grid method using an auger. Samples were taken from horizons in each profile for laboratory analyses. Organic matter contents ranged from 12.5 to 91.5% across all four pedons. Fiber contents were between 4.3 and 91.5%, and N ranged from 0.56 to 2.19%. Cation exchange capacity ranged from 37 to 222 cmol kg-1, bulk density from 0.09 to 0.78 g cm-3, lime from 0.15 to 2.62%. The pH and ECe values ranged from 5.38 to 7.92 and 0.50 to 3.80 dS m-1, respectively. Sand, silt and clay contents of the organic soils ranged between 0.75-3.92, 40.70-74.77 and 24.15-57.30%, respectively. Differences in organic soils were found to depend on the environment, botanical origins, decomposition degrees, and groundwater composition. The organic soils of the research area were classified in the typic, hemic and hydric subgroups of Medifibrists (Soil Taxonomy 1999).

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

    PubMed

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

    2006-11-01

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

  15. 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

  16. Prediction of the solubility of zinc, copper, nickel, cadmium, and lead in metal-contaminated soils.

    PubMed

    Zan, Nafiseh Rang; Datta, S P; Rattan, R K; Dwivedi, B S; Meena, M C

    2013-12-01

    Risk assessment of metal-contaminated soil depends on how precisely one can predict the solubility of metals in soils. Responses of plants and soil organisms to metal toxicity are explained by the variation in free metal ion activity in soil pore water. This study was undertaken to predict the free ion activity of Zn, Cu, Ni, Cd, and Pb in metal-contaminated soil as a function of pH, soil organic carbon, and extractable metal content. For this purpose, 21 surface soil samples (0-15 cm) were collected from agricultural lands of various locations receiving sewage sludge and industrial effluents for a long period. One soil sample was also collected from agricultural land which has been under intensive cropping and receiving irrigation through tube well water. Soil samples were varied widely in respect of physicochemical properties including metal content. Total Zn, Cu, Ni, Cd, and Pb in experimental soils were 2,015 ± 3,373, 236 ± 286, 103 ± 192, 29.8 ± 6.04, and 141 ± 270 mg kg(-1), respectively. Free metal ion activity, viz., pZn(2+), pCu(2+), pNi(2+), pCd(2+), and pPb(2+), as estimated by the Baker soil test was 9.37 ± 1.89, 13.1 ± 1.96, 12.8 ± 1.89, 11.9 ± 2.00, and 11.6 ± 1.52, respectively. Free metal ion activity was predicted by pH-dependent Freundlich equation (solubility model) as a function of pH, organic carbon, and extractable metal. Results indicate that solubility model as a function of pH, Walkley-Black carbon (WBC), and ethylenediaminetetraacetic acid (EDTA)-extractable metals could explain the variation in pZn(2+), pCu(2+), pNi(2+), pCd(2+), and pPb(2+) to the extent of 59, 56, 46, 52, and 51%, respectively. Predictability of the solubility model based on pH, KMnO4-oxidizable carbon, and diethylenetriaminepentaacetic acid-extractable or CaCl2-extractable metal was inferior compared to that based on EDTA-extractable metals and WBC.

  17. 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.

  18. Arsenic status and distribution in soils at disused cattle dip in South Africa.

    PubMed

    Okonkwo, Jonathan Okechukwu

    2007-10-01

    The status and the distribution of arsenic in soils from a disused cattle dip were determined. Elevated total arsenic levels (1,033-1,369 mg/L) were detected in the soils. Significant difference (p < 0.05) between the values for the soils obtained from the contaminated sites and control site (0.15 mg/L) was observed. The level of total arsenic decreased with increase in depth. The peak total arsenic (1,369 mg/L) was obtained at 0 cm depth, indicating the abundance of arsenic at the surface despite the fact that the dip has been out of use for a long time. The total arsenic recorded for different depths were significantly higher than the trigger value of 40 mg/kg. The distribution of arsenic in the different phases showed that arsenic was mostly bound to the residual fractions (52%) and Fe and Al hydroxides (21%). The distribution of arsenic in the order phases was in the following order: exchangeable (14%), carbonates (10%) and soluble (3%).

  19. 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

  20. Factors regulating soil surface CO2 and NOx flux in response to high temperature, pulse water events, and nutrient fertilization

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Grantz, D. A.; Chatterjee, A.; Eberwein, J. R.; Allsman, L. A.; Jenerette, D.

    2012-12-01

    Trace gas emissions from the soil surface are often underestimated due to poor understanding of the factors regulating fluxes under extreme conditions when moisture can be highly variable. In particular, dynamics of soil surface trace gas emissions from hot agricultural regions can be difficult to predict due to the sporadic use of flood irrigation and nitrogen fertilization. Soil surface CO2 and NOx fluxes are especially difficult to predict due to nonlinear responses to pulse water and fertilization events. Additionally, models such as Lloyd and Taylor (1994) and Yienger and Levy II (1995) are not well parameterized for soil surface CO2 and NOx flux, respectively, under excessively high temperatures. We measured soil surface CO2 and NOx flux in an agricultural field transitioning from fallow to biofuel crop production (Sorghum bicolor). Soil surface CO2 flux was measured using CO2 probes coupled with the flux-gradient method. NOx measurements were made using chambers coupled with a NOx monitor. Our field site is located at the University of California Desert Research and Extension Center in the Imperial Valley of CA. Air temperatures regularly exceed 42°C in the summer. Flood irrigation is used at the site as well as nitrogen fertilizers. Soil respiration ranged from 0-15 μmoles CO2 m-2 s-1, with strong hysteresis observed both with and without plants. Soil CO2 fluxes measured in the fallow field before the biofuel crop was planted were temperature independent and mainly regulated by soil moisture. When plants were introduced, temperature became an important predictor for soil respiration as well as canopy height. NOx fluxes were highest at intermediate soil moisture and varied significantly across an irrigation cycle. NOx emissions were temperature dependent, ranging from 3-113 ng N cm-2 hr-1. Neither CO2 nor NOx emissions showed inhibition at soil temperatures up to 55°C. Models may underestimate fluxes of CO2 and NOx from hot agricultural regions due to

  1. CM-2 Environmental / Modal Testing of Spacehab Racks

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Goodnight, Thomas W.; Farkas, Michael A.

    2001-01-01

    Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS 107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the Shuttle.

  2. 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.

  3. Soil water repellency of Antarctic soils (Elephant Point). First results

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Oliva, Marc; Ruiz Fernández, Jesus

    2015-04-01

    Hydrophobicity it is a natural properties of many soils around the world. Despite the large body of research about soil water hydrophobicity (SWR) in many environments, little information it is available about Antarctic soils and their hydro-geomorphological consequences. According to our knowledge, no previous work was carried out on this environment. Soil samples were collected in the top-soil (0-5 cm) and SWR was analysed according to the water drop penetration test. The preliminary results showed that all the soils collected were hydrophilic, however further research should be carried out in order to understand if SWR changes with soil depth and if have implications on soil infiltration during the summer season.

  4. 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...

  5. Evidence for live Cm-247 in the early solar system

    NASA Technical Reports Server (NTRS)

    Tatsumoto, M.; Shimamura, T.

    1980-01-01

    Variations of the U-238/U-235 ratio in the Allende meteorite, ranging from -35% to +19% are interpreted as evidence of live Cm-247 in the early solar system. The amounts of these and other r-products in the solar system indicate values of (9000 + or - 3000) million years for the age of the Galaxy and approximately 8 million years 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 of products of Cm-247, Al-27, Pu-244, and I-129.

  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. Precise measurements of primordial power spectrum with 21 cm fluctuations

    SciTech Connect

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

    2013-10-01

    We discuss the issue of how precisely we can measure the primordial power spectrum by using future observations of 21 cm fluctuations and cosmic microwave background (CMB). For this purpose, we investigate projected constraints on the quantities characterizing primordial power spectrum: the spectral index n{sub s}, its running α{sub s} and even its higher order running β{sub s}. We show that future 21 cm observations in combinations with CMB would accurately measure above mentioned observables of primordial power spectrum. We also discuss its implications to some explicit inflationary models.

  8. 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.

  9. 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

  10. DEEP 21 cm H I OBSERVATIONS AT z {approx} 0.1: THE PRECURSOR TO THE ARECIBO ULTRA DEEP SURVEY

    SciTech Connect

    Freudling, Wolfram; Zwaan, Martin; Staveley-Smith, Lister; Meyer, Martin; Catinella, Barbara; Minchin, Robert; Calabretta, Mark; Momjian, Emmanuel; O'Neil, Karen

    2011-01-20

    The 'ALFA Ultra Deep Survey' (AUDS) is an ongoing 21 cm spectral survey with the Arecibo 305 m telescope. AUDS will be the most sensitive blind survey undertaken with Arecibo's 300 MHz Mock spectrometer. The survey searches for 21 cm H I line emission at redshifts between 0 and 0.16. The main goals of the survey are to investigate the H I content and probe the evolution of H I gas within that redshift region. In this paper, we report on a set of precursor observations with a total integration time of 53 hr. The survey detected a total of eighteen 21 cm emission lines at redshifts between 0.07 and 0.15 in a region centered around {alpha}{sub 2000} {approx} 0{sup h}, {delta} {approx} 15{sup 0}42'. The rate of detection is consistent with the one expected from the local H I mass function. The derived relative H I density at the median redshift of the survey is {rho}{sub H{sub I}}[z = 0.125] = (1.0 {+-} 0.3){rho}{sub 0}, where {rho}{sub 0} is the H I density at zero redshift.

  11. [Soil moisture dynamics of apple orchard in Loess Plateau dryland].

    PubMed

    Zhao, Gang; Fan, Ting-lu; Li, Shang-zhong; Zhang, Jian-jun; Wang, Yong; Dang, Yi; Wang, Lei

    2015-04-01

    The soil moisture of 0-500 cm soil layer in a dryland orchard at its full fruit period was measured from 2009 to 2013 to explore the soil moisture dynamics. Results indicated that soil water consumption mainly occurred in the soil layer of 0-300 cm in normal rainfall year and below the 300 cm soil layer when the annual rainfall was less than 400 mm. The soil moisture in the 200-300 cm soil layer fluctuated most and was affected by rainfall and apple consumption. Seasonal drought usually happened between April and late June, while the accumulation of soil moisture mainly occurred in the rainy season from July to mid-October to alleviate the drought effectively in next spring.

  12. 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

  13. 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.

  14. 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.

  15. X-ray absorption spectroscopic study of chemically and electrochemically Li ion extracted Li{sub y}Co{sub 0.85}Al{sub 0.15}O{sub 2} compounds

    SciTech Connect

    Kim, M.G.; Yo, C.H.

    1999-08-05

    The local structure refinements for chemically and electrochemically Li ion extracted Li{sub y}Co{sub 0.85}Al{sub 0.15}O{sub 2} compounds have been investigated by Co K-edge X-ray absorption spectroscopy. In the X-ray absorption near-edge structure (XANES), the 1s {r_arrow} 3d transition at {approximately} 7,709.9 eV and 1s {r_arrow} 4p transition at {approximately} 7,727.8 eV for the pristine LiCo{sub 0.85}Al{sub 0.15}O{sub 2} have shifted effectively to higher energy regions of {approximately} 0.6 eV and {approximately} 2.5 eV for the higher Li ion extraction, respectively, which shows that the average oxidation state of Co ion increases gradually with the extraction. The systematic variations of peak intensities for the 1s {r_arrow} 3d transition and 1s {r_arrow} 4p transition result from Co 3d and 4p orbital mixing by the local structure distortion around Co atoms. In particular, the abrupt decrease of peak intensity for 1s {r_arrow} 4p transition with shakedown process by ligand to metal charge transfer (LMCT) represents the transfer of the hole state from the oxygen to Co atom and the localization at the Co atomic site as a form of Co{sup IV} ion by structural distortion. The XANES features for the electrochemical extraction have shown that the electrochemical redox reaction is always not reversible in the Li ion extraction/insertion process. From the extended X-ray absorption fine structure (EXAFS) refinement, the interatomic distances of bond pairs decrease for the Li ion extraction. The chemical and electrochemical extractions have a significant effect on Fourier transform (FT) magnitude, which decreases linearly with the extraction. Since single and multiple scatterings with Co atoms have predominantly contributed to the FT magnitudes, the systematic decrease of FT magnitude is closely related to the static disorder of two different oxidative Co{sup III} and Co{sup IV} ions. This fact is consistent with the increase of the Debye-Waller factor for each

  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. 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.

  18. 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.

  19. Preparing for ICD-10-CM in physician practices.

    PubMed

    Kuehn, Lynn

    2009-08-01

    What will change under CD-10-CM, and what must be done to prepare? This is the year for physician practices to get their ducks in a row: become informed, assess their IT and training needs, and make a plan that leads to the October 1, 2013, deadline.

  20. Calorimetric determination of kQ factors for NE 2561 and NE 2571 ionization chambers in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV photons

    NASA Astrophysics Data System (ADS)

    Krauss, Achim; Kapsch, Ralf-Peter

    2007-10-01

    The relative uncertainty of the ionometric determination of the absorbed dose to water, Dw, in the reference dosimetry of high-energy photon beams is in the order of 1.5% and is dominated by the uncertainty of the calculated chamber- and energy-dependent correction factors kQ. In the present investigation, kQ values were determined experimentally in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV bremsstrahlung by means of a water calorimeter operated at 4 °C. Ionization chambers of the types NE 2561 and NE 2571 were calibrated directly in the water phantom of the calorimeter. The measurements were carried out at the linear accelerator of the Physikalisch-Technische Bundesanstalt. It is shown that the kQ factor of a single ionization chamber can be measured with a standard uncertainty of less than 0.3%. No significant variations of kQ were found for the different lateral sizes of the radiation fields used in this investigation.

  1. The 21 cm signature of a cosmic string loop

    SciTech Connect

    Pagano, Michael; Brandenberger, Robert E-mail: rhb@physics.mcgill.ca

    2012-05-01

    Cosmic string loops lead to nonlinear baryon overdensities at early times, even before the time which in the standard LCDM model corresponds to the time of reionization. These overdense structures lead to signals in 21 cm redshift surveys at large redshifts. In this paper, we calculate the amplitude and shape of the string loop-induced 21 cm brightness temperature. We find that a string loop leads to a roughly elliptical region in redshift space with extra 21 cm emission. The excess brightness temperature for strings with a tension close to the current upper bound can be as high as 1deg K for string loops generated at early cosmological times (times comparable to the time of equal matter and radiation) and observed at a redshift of z+1 = 30. The angular extent of these predicted 'bright spots' is x{sup '}. These signals should be detectable in upcoming high redshift 21 cm surveys. We also discuss the application of our results to global monopoles and primordial black holes.

  2. 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…

  3. Modifying broiler diets with phytase and vitamin D metabolite (25-OH D(3)): impact on phosphorus in litter, amended soils, and runoff.

    PubMed

    McGrath, Joshua M; Sims, J Thomas; Maguire, Rory O; Saylor, William W; Angel, Roselina

    2010-01-01

    Adding phytase and 25- hydroxycholecalciferol (25-OH D(3)) to broiler diets has been shown effective at reducing total P concentrations in broiler litter. This study was conducted to determine the impact of field application of broiler litter from modified diets on P solubility in litter-amended soils and P losses in runoff. Five broiler diets and their resulting litters were evaluated: a high P diet, a low P diet, each of those basal diets with phytase added, and a low P diet with phytase and 25-OH D(3) added. A field study was initiated at two sites with each of the five broiler litters and a commercial P fertilizer (triple superphosphate [TSP]) applied at the same total P rate (150 kg P ha(-1)) and a control where no P was applied. Soil P was monitored over time at two depths (0-5 cm and 0-15 cm) soils were collected in the spring and fall to perform rainfall simulation studies. Broiler litter or TSP application increased soil water-soluble P and Mehlich 3-P concentrations relative to the control, however there were no consistent differences detected between litter treatments. Results from the rainfall simulation experiments indicate that diet modification with phytase or 25-OH D(3) does not increase the potential for P losses in runoff from amended soils relative to traditional diets. Moreover, broiler diet modification to reduce excreted P could be a potentially effective method for reducing watershed scale P surpluses in areas of intensive broiler production, without raising concerns over soluble P losses from litter-amended soils. PMID:20048320

  4. Where Is Needle- and Root-Derived Soil Organic Matter After 10 Years of Decomposition in a Temperate Forest?

    NASA Astrophysics Data System (ADS)

    Hicks Pries, C.; Hatton, P.; Castanha, C.; Bird, J. A.; Torn, M. S.

    2013-12-01

    the soil than needle litter C (about 25%). Less than 0.15% of the remaining litter C (0.06% of originally applied) was found actively cycling in microbial PLFA's. Needle and root C did not differ in the amount remaining still in the active microbial pool. Preliminary data indicate that unlike after one year, there were no microbial groups with strong preferences for the added root or needle C relative to other microbial groups. The amount of root and needle C and N associated with the different mineral groups will also be presented.

  5. The role of irrigation in the soil-crop system

    NASA Astrophysics Data System (ADS)

    Széles, Adrienn; Ragán, Péter; Nagy, János

    2015-04-01

    Agricultural production is performed in 85.5% of the total area of Hungary. Yearly average precipitation is 550-600 mm. Due to global warming, flooding, inland inundation and drought are frequent within a year. Extreme weather circumstances pose new challenges for crop producers. The results of long-term field experiments provide guidance to how each production technological intervention affects crop production, average yield and yield security. Examinations were performed on mid-heavy calcareous chenozem soil in a multifactorial small plot long-term field experiment under natural precipitation supply and irrigated circumstances to analyse the effect of irrigation and N fertilisation on soil moisture and maize grain yield. Drought and optimal years were involved in the examination. Six fertiliser treatments were used (0, 30, 60, 90, 120, 150 kg N ha-1) each year. Irrigation was performed with a Valmont linear equipment. Changes in soil moisture balance were examined with TDR-based soil moisture probes in the 0-120 cm profile. Evaluation was performed with SPSS. The moisture profiles of the 1.2 m soil profile show contrasting tendencies in different crop years in both irrigation treatments. In drought years, the 0-0.15 m layer showed the lowest moisture values (8.3-9.6 v/v%), increasing towards deeper layers. The significant (p<0.05) moisture content difference of 11-12 v/v% measured at the 12-leaf-stage constantly decreased by the end of the growing season as soil moisture stock decreased. In wet years, the highest moisture content was observed in the 0.15-0.30 m layer (37-39v/v%), decreasing towards deeper layers (13-16 v/v%). At natural precipitation supply, yield linearly increased until 60 kg ha-1 N in both years, but no yield surplus was obtained above this dose. Our results show that increasing N doses do not always cause yield increase if the water needed for nutrient uptake is limited. In irrigated treatments, the highest statistically significant yield was

  6. 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.

  7. 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

  8. 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.

  9. 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…

  10. 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.…

  11. Fractionating soils so that others do not have to: radiocarbon informs choice of method for scale, ecosystem, or process

    NASA Astrophysics Data System (ADS)

    Crow, S. E.

    2011-12-01

    stock in the top 0-15 cm of mineral soil by 26%; however, sequential density separation into 7 fractions revealed 50-69% increases in C within low density fractions with MRT of less than 5 yr but over 300% losses of soil C within dense fraction with MRT of over 1275 yr. In these Andisols, the sequential density fractionation method was highly sensitive to land use change and the range of densities are hypothesized to be associated with different mechanisms for soil C stabilization acting over different time scales, which was confirmed by the radiocarbon-based MRT estimates. Although soil fractionation methods are powerful, other results from similar Andisols suggest that over geologic time scales MRT estimates for bulk soil profiles can be more informative than soil fractions. Careful consideration of the scientific question, study system, and scale is important when choosing a method for fractionating soil. Radiocarbon measurements can provide confirmation that the actual nature of the recovered fractions matches the theoretical one.

  12. 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.

  13. 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

  14. 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.

  15. Uniaxial Fermi-surface nesting and spin-density-wave transition in the heavy-fermion compound Ce(Ru{sub 0.85}Rh{sub 0.15}){sub 2}Si{sub 2}

    SciTech Connect

    Murayama, S.; Sekine, C.; Yokoyanagi, A.; Hoshi, K.; Onuki, Y.

    1997-11-01

    Resistivity parallel and perpendicular to the tetragonal c axis of the antiferromagnetic heavy-fermion compound Ce(Ru{sub 1{minus}x}Rh{sub x}){sub 2}Si{sub 2} for x=0.15 has been measured in various fields along the c axis of the single crystal. A sharp upturn is observed just below the N{acute e}el temperature T{sub N} only in the parallel direction. This is interpreted in terms of partial gapping of the Fermi surface along the uniaxial c direction. The specific heat and susceptibility below T{sub N} are, respectively, analyzed into two independent contributions in the low-temperature limit: one is an exponential contribution of the gapped part of the Fermi surface with the energy gap about 10 K, and the other is a residual heavy-fermion contribution due to the remaining ungapped part of about 65{percent}. These facts suggest an itinerant spin-density-wave transition based on Fermi-surface nesting in a heavy-electron band. {copyright} {ital 1997} {ital The American Physical Society}

  16. Evolution of local structures in polycrystalline Zn1−xMgxO (0<=x<=0.15) studied by Raman spectroscopy and synchrotron x-ray pair-distribution-function analysis

    SciTech Connect

    Kim, Young-Il; Page, Katharine; Limarga, Andi M.; Clarke, David R.; Seshadri, Ram

    2008-09-18

    The local structures of Zn{sub 1-x}Mg{sub x}O alloys have been studied by Raman spectroscopy and by synchrotron x-ray pair-distribution-function (PDF) analysis. Within the solid solution range (0 {le} x {le} 0.15) of Zn{sub 1-x}Mg{sub x}O, the wurtzite framework is maintained with Mg homogeneously distributed throughout the wurtzite lattice. The E{sub 2}{sup high} Raman line of Zn{sub 1-x}Mg{sub x}O displays systematic changes in response to the evolution of the crystal lattice upon the Mg substitution. The redshift and broadening of the E{sub 2}{sup high} mode are explained by the expansion of hexagonal ab dimensions and compositional disorder of Zn/Mg, respectively. Synchrotron x-ray PDF analyses of Zn{sub 1-x}Mg{sub x}O reveal that the Mg atoms have a slightly reduced wurtzite parameter u and more regular tetrahedral bond distances than the Zn atoms. For both Zn and Mg, the internal tetrahedral geometries are independent of the alloy composition.

  17. 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.

  18. A comprehensive study on electrochemical performance of Mn-surface-modified LiNi0.8Co0.15Al0.05O2 synthesized by an in situ oxidizing-coating method

    NASA Astrophysics Data System (ADS)

    Huang, Bin; Li, Xinhai; Wang, Zhixing; Guo, Huajun; Shen, Li; Wang, Jiexi

    2014-04-01

    The degradation of Ni-rich LiNi0.8Co0.15Al0.05O2 cathode material is successfully suppressed via a facile in situ oxidizing-coating method. KMnO4 is used as not only a Mn source but also an oxidant. X-ray diffraction (XRD) and scanning electron microscope (SEM) results demonstrate that the structure and morphology of the KMnO4-pretreated sample are the same as the pristine one. X-ray photoelectron spectroscopy (XPS) confirms that the valence state of Mn is +4 and the Ni3+ ions are partly reduced to Ni2+ when the material is doped with Mn4+. Besides, the Mn4+ ions are proved to distribute uniformly on the surface of the materials particles through energy dispersive spectrometer (EDS) and EDS elemental mapping. And it is confirmed that the concentration of Ni in the outer layer is reduced by the Mn-surface-modification. From the electrochemical characterizations, it is confirmed that the presence of tetravalent Mn at the surface can suppress the capacity fading during charge-discharge cycles, even under elevated temperature and overcharge conditions, and can prevent the material from deterioration during storage in air.

  19. Anisotropy of electric resistance and upper critical field in magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We have measured temperature dependencies of the electric resistance R and upper critical magnetic field Hc2 of a magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4. The measurements were made for different angles φ of the magnetic field inclination to the direction of measuring current and revealed strong anisotropy of the behavior of R(T) and the values of Hc2(T). By using the Werthamer-Gelfand-Hohenberg theory, we determined the Maki parameter α and the parameter of the spin-orbital interaction. For φ =0∘ and 90° both parameters are close to zero, thus the magnitude of Hc2(0) ≈ 38 kOe is basically limited by the orbital effect. At φ =45∘ , a large value of α = 4.2 indicates dominating role of the spin-paramagnetic effect in the suppression of Hc2(0) down to 8.8 kOe. We suggest that such behavior of R(T) and Hc2(T) is caused by internal magnetism of the Dy atoms which may strongly depend on the magnetic field orientation.

  20. A microwave-assisted sol-gel Pechini method for the synthesis of BaCe{sub 0.65}Zr{sub 0.20}Y{sub 0.15}O{sub 3-{delta}} powders

    SciTech Connect

    Barison, S.; Fabrizio, M.; Fasolin, S.; Montagner, F.; Mortalo, C.

    2010-09-15

    In this work, BaCe{sub 0.65}Zr{sub 0.20}Y{sub 0.15}O{sub 3-{delta}} powders with a perovskite-type structure were successfully synthesized by a microwave-assisted sol-gel Pechini method (SGP). By comparison, powders having the same nominal stoichiometry were also prepared without the microwave assistance. For the syntheses, nitrates were used as metal precursors, and ethylenediaminetetraacetic acid and ethylene glycol were used as complexing and polymerizing agents, respectively. An extensive structural and morphological investigation by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) has been performed. Moreover, in order to check the phase transitions, simultaneous thermogravimetric and differential thermal analyses were (TG-DTA) performed on gels. With respect to the conventional Pechini method, the microwave-assisted process guaranteed a faster, energy-saving procedure for obtaining single-phase nanopowders of high purity. Moreover, a significant increase in pellet densities was achieved owing to a higher grain coalescence.

  1. Magnetic measurement of RF-induced flux lattice annealing (RIFLA) in the electron-doped superconductor Pr1.85Ce0.15CuO4-y.

    NASA Astrophysics Data System (ADS)

    Clark, W. G.; Gaidos, G.; Wu, G.; Brown, S. E.; Greene, R. L.; Balci, H.

    2007-03-01

    A strained flux lattice (FL) in a superconductor (SC) can be annealed to a lower free energy by the RF-field used to generate an NMR spin-echo signal [W.G. Clark et al., J. Phys. IV Proceedings 9, Pr10-49-52 (1999)]. Here, we report the change in the rf magnetic susceptibility (χ) in the SC phase of a single crystal of Pr1.85Ce0.15CuO4-y with a strained FL by successive RIFLA pulses. The distorted FL is prepared by rotating the sample through a small angle in a magnetic field well below the SC transition temperature, leaving the FL pinned in a non-equilibrium configuration. RIFLA pulses then reduce χ, which is measured by the change in the inductance of a coil surrounding the sample using an NMR probe and spectrometer. The interpretation is that shaking the FL by the RF pulses progressively anneals it to a lower free energy configuration, which has a smaller χ. These measurements provide a very sensitive measure of the RIFLA effect. Work at UCLA was supported by NSF Grants DMR-0334869 (WGC) and DMR-0520552 (SEB).

  2. 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.

  3. 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.

  4. Absence of nematic order in the pressure-induced intermediate phase of the iron-based superconductor B a0.85K0.15F e2A s2

    NASA Astrophysics Data System (ADS)

    Zheng, Yan; Tam, Pok Man; Hou, Jianqiang; Böhmer, Anna E.; Wolf, Thomas; Meingast, Christoph; Lortz, Rolf

    2016-03-01

    The hole doped Fe-based superconductors B a1-xAxF e2A s2 (where A =Na or K) show a particularly rich phase diagram. It was observed that an intermediate reentrant tetragonal phase, in which the C4 fourfold rotational symmetry is restored, forms within the orthorhombic antiferromagnetically ordered stripe-type spin density wave state above the superconducting transition [S. Avci et al., Nat. Commun. 5, 3845 (2014);, 10.1038/ncomms4845 A. E. Böhmer et al., Nat. Commun. 6, 7911 (2015), 10.1038/ncomms8911]. A similar intermediate phase was reported to appear if pressure is applied to underdoped B a1-xKxF e2A s2 [E. Hassinger et al., Phys. Rev. B 86, 140502(R) (2012), 10.1103/PhysRevB.86.140502]. Here we report data of the electric resistivity, Hall effect, specific heat, and the thermoelectric Nernst and Seebeck coefficients measured on a B a0.85K0.15F e2A s2 single crystal under pressure up to 5.5 GPa. The data reveal a coexistence of the intermediate phase with filamentary superconductivity. The Nernst coefficient shows a large signature of nematic order that coincides with the stripe-type spin density wave state up to optimal pressure. In the pressure-induced intermediate phase the nematic order is removed, thus confirming that its nature is a reentrant tetragonal phase.

  5. 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.

  6. 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.

  7. Surface degradation of Li1-xNi0.80Co0.15Al0.05O2 cathodes: Correlating charge transfer impedance with surface phase transformations

    NASA Astrophysics Data System (ADS)

    Sallis, S.; Pereira, N.; Mukherjee, P.; Quackenbush, N. F.; Faenza, N.; Schlueter, C.; Lee, T.-L.; Yang, W. L.; Cosandey, F.; Amatucci, G. G.; Piper, L. F. J.

    2016-06-01

    The pronounced capacity fade in Ni-rich layered oxide lithium ion battery cathodes observed when cycling above 4.1 V (versus Li/Li+) is associated with a rise in impedance, which is thought to be due to either bulk structural fatigue or surface reactions with the electrolyte (or combination of both). Here, we examine the surface reactions at electrochemically stressed Li1-xNi0.8Co0.15Al0.05O2 binder-free powder electrodes with a combination of electrochemical impedance spectroscopy, spatially resolving electron microscopy, and spatially averaging X-ray spectroscopy techniques. We circumvent issues associated with cycling by holding our electrodes at high states of charge (4.1 V, 4.5 V, and 4.75 V) for extended periods and correlate charge-transfer impedance rises observed at high voltages with surface modifications retained in the discharged state (2.7 V). The surface modifications involve significant cation migration (and disorder) along with Ni and Co reduction, and can occur even in the absence of significant Li2CO3 and LiF. These data provide evidence that surface oxygen loss at the highest levels of Li+ extraction is driving the rise in impedance.

  8. 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. Insights on the fundamental lithium storage behavior of all-solid-state lithium batteries containing the LiNi0.8Co0.15Al0.05O2 cathode and sulfide electrolyte

    NASA Astrophysics Data System (ADS)

    Peng, Gang; Yao, Xiayin; Wan, Hongli; Huang, Bingxin; Yin, Jingyun; Ding, Fei; Xu, Xiaoxiong

    2016-03-01

    An insightful study on the fundamental lithium storage behavior of all-solid-state lithium battery with a structure of LiNi0.8Co0.15Al0.05O2 (NCA)/Li10GeP2S12/Li-In is carried out in this work. The relationship between electrochemical performances and particle size, surface impurities and defects of the NCA positive material is systematically investigated. It is found that a ball-milling technique can decrease the particle size and remove surface impurities of the NCA cathode while also give rise to surface defects which could be recovered by a post-annealing process. The results indicate that the interfacial resistance between the NCA and Li10GeP2S12 is obviously decreased during the ball-milling followed by a post-annealing. Consequently, the discharge capacity of NCA in the NCA/Li10GeP2S12/Li-In solid-state battery is significantly enhanced, which exhibits a discharge capacity of 146 mAh g-1 at 25 °C.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. NMR evidence of LiF coating rather than fluorine substitution in Li(Ni{sub 0.425}Mn{sub 0.425}Co{sub 0.15})O{sub 2}

    SciTech Connect

    Menetrier, M.; Bains, J.; Croguennec, L. Flambard, A.; Bekaert, E.; Jordy, C.; Biensan, Ph.; Delmas, C.

    2008-12-15

    A series of 'Li{sub 1+z/2}(Ni{sub 0.425}Mn{sub 0.425}Co{sub 0.15}){sub 1-z/2}O{sub 2-z}F{sub z}' materials was prepared by a coprecipitation route and their structure was characterized using X-ray diffraction (XRD), as well as {sup 7}Li and {sup 19}F Magic Angle Spinning (MAS) NMR spectroscopy. Two hypotheses were considered: (i) formation of layered oxyfluoride materials and (ii) formation of a mixture between the layered material and LiF. Structural parameters were refined by the Rietveld method, using XRD diffraction data. The refinement results did not allow us to choose between these two hypotheses: no significant change in crystallinity and structural parameters was observed irrespective of the fluorine ratio. {sup 7}Li and {sup 19}F MAS NMR analyses showed signals with isotropic positions characteristic of LiF, but envelopes characteristic of very strong dipolar interactions with the electron spins of the material, demonstrating that LiF was not incorporated into the layered oxide structure but was instead present as a coating. - Graphical abstract: {sup 7}Li and {sup 19}F MAS NMR show signals with isotropic positions characteristic of LiF, but with spinning sidebands envelopes characteristic of very strong dipolar interactions with the electron spins of the layered oxide, demonstrating that F is not a part of the material but is present as an LiF coating.

  17. Dielectric and piezoelectric properties of lead-free Ba0.85Ca0.15Ti0.9-xZr0.1CuxO3 ceramics synthesized by a hydrothermal method

    NASA Astrophysics Data System (ADS)

    Hunpratub, Sitchai; Phokha, Sumalin; Maensiri, Santi; Chindaprasirt, Prinya

    2016-04-01

    Ba0.85Ca0.15Ti0.9Zr0.1-xCuxO3 (BCTZC) nanopowders were synthesized using a hydrothermal method after which they were pressed into discs and sintered in air at 1300 °C for 3 h to form ceramic samples. The phase and microstructure of the powder and ceramic samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results indicated that the ceramic samples exhibited a tetragonal structure and that CuO, BaZrO3 or CaTiO3 impurity phases, which had been present in the powder samples, were not observed. The average grain sizes in the ceramic samples were found to be 17.0, 16.1, 20.0, 18.1 and 19.6 μm for Cu mole fractions x of 0.002, 0.004, 0.006, 0.008 and 0.01, respectively. The dielectric constants, ferroelectric hysteresis loops and piezoelectric charge coefficients of the BCZTC ceramic samples were also investigated. Optimum values for the relative dielectric constant (ɛ‧), tan δ and piezoelectric charge coefficient (d33) of the samples were 3830, 0.03 and 306 pC/N, respectively, in the Cu mole fraction samples with x = 0.002.

  18. Atomic resolution imaging of oxygen atoms close to heavy atoms by HRTEM and ED, using the superconductor SmFeAsO0.85F0.15 as an example.

    PubMed

    Wang, Yumei; Ge, Binghui; Che, Guangcan

    2015-04-01

    Imaging of light atoms has always been a challenge in high-resolution electron microscopy. Image resolution is mainly limited by lens aberrations, especially the spherical aberration of the objective lens. Image deconvolution could correct for the image distortion by lens aberrations and restore the structure projection, the resolution of which is limited by the information limit of the microscope. Electron diffraction unrestricted by lens aberrations could overcome this resolution limit. Here we show a combination of electron diffraction and image deconvolution to reveal simultaneously the atomic columns of O and considerably heavier Sm at a very close distance (1.17 Å) in iron-based superconductor SmFeAsO0.85F0.15 using a conventional 200 kV electron microscope. The approach used here, starting from an image and an electron diffraction pattern, has an advantage for those radiation-sensitive samples. Besides, it can be applied to simultaneously imaging light and heavy atoms, even though they have a big difference in atomic number and a much smaller atomic distance than the microscope resolution.

  19. The Paris meteorite, the least altered CM chondrite so far

    NASA Astrophysics Data System (ADS)

    Hewins, Roger H.; Bourot-Denise, Michèle; Zanda, Brigitte; Leroux, Hugues; Barrat, Jean-Alix; Humayun, Munir; Göpel, Christa; Greenwood, Richard C.; Franchi, Ian A.; Pont, Sylvain; Lorand, Jean-Pierre; Cournède, Cécile; Gattacceca, Jérôme; Rochette, Pierre; Kuga, Maïa; Marrocchi, Yves; Marty, Bernard

    2014-01-01

    The Paris chondrite provides an excellent opportunity to study CM chondrules and refractory inclusions in a more pristine state than currently possible from other CMs, and to investigate the earliest stages of aqueous alteration captured within a single CM bulk composition. It was found in the effects of a former colonial mining engineer and may have been an observed fall. The texture, mineralogy, petrography, magnetic properties and chemical and isotopic compositions are consistent with classification as a CM2 chondrite. There are ∼45 vol.% high-temperature components mainly Type I chondrules (with olivine mostly Fa0-2, mean Fa0.9) with granular textures because of low mesostasis abundances. Type II chondrules contain olivine Fa7 to Fa76. These are dominantly of Type IIA, but there are IIAB and IIB chondrules, II(A)B chondrules with minor highly ferroan olivine, and IIA(C) with augite as the only pyroxene. The refractory inclusions in Paris are amoeboid olivine aggregates (AOAs) and fine-grained spinel-rich Ca-Al-rich inclusions (CAIs). The CAI phases formed in the sequence hibonite, perovskite, grossite, spinel, gehlenite, anorthite, diopside/fassaite and forsterite. The most refractory phases are embedded in spinel, which also occurs as massive nodules. Refractory metal nuggets are found in many CAI and refractory platinum group element abundances (PGE) decrease following the observed condensation sequences of their host phases. Mn-Cr isotope measurements of mineral separates from Paris define a regression line with a slope of 53Mn/55Mn = (5.76 ± 0.76) × 106. If we interpret Cr isotopic systematics as dating Paris components, particularly the chondrules, the age is 4566.44 ± 0.66 Myr, which is close to the age of CAI and puts new constraints on the early evolution of the solar system. Eleven individual Paris samples define an O isotope mixing line that passes through CM2 and CO3 falls and indicates that Paris is a very fresh sample, with variation explained

  20. Extractable hydrocarbons, nickel and vanadium contents of Ogbodo-Isiokpo oil spill polluted soils in Niger Delta, Nigeria.

    PubMed

    Osuji, Leo C; Adesiyan, Samuel O

    2005-11-01

    An oil spill polluted site at Ogbodo-Isiokpo in Ikwere Local Government Area of Rivers State in southern Nigeria, was identified for study following three successive reconnaissance surveys of oil fields in the Agbada west plain of Eastern Niger Delta. A sampling area of 200 m x 200 m was delimited at the oil spill impacted site using the grid technique and soils were collected at surface (0-15 cm) and subsurface (15-30 cm) depths from three replicate quadrats. A geographically similar, unaffected area, located 50 m adjacent to the polluted site, was chosen as a control (reference) site. Total extractable hydrocarbon contents of the polluted soils ranged from 3.02-4.54 and 1.60-4.20 mg/kg (no overlap in standard errors) at surface and subsurface depths respectively. The concentrations of two "diagnostic" trace heavy metals, nickel (Ni) and vanadium (V), which are normal constituents of crude oil, were also determined in the soils by atomic absorption spectrophotometric method after pre-extraction of cations with dithionite-citrate carbonate. Ni varied from 0.15 to 1.65 mg/kg in the polluted plots and from 0.18 to 0.82 mg/kg in the unpolluted plots; vanadium varied from 0.19 to 0.70 mg/kg in the polluted plots and from 0.14 to 0.38 mg/kg in the unpolluted plots. Ni and V were more enhanced (p < 0.05) in the oil-polluted soils, especially at subsurface depth. Whilst the oil spillage could be said to be indirectly responsible for the enhanced concentrations of nickel and vanadium via the injection and availability of the petroleum hydrocarbons that might have increased the activities of biodegradation on site, the physico-chemical properties of the soils and inherent mobility of metals, as well as the intense rainfall and flooding that characterized the period of study, may have also contributed, at least in part, to these enhanced concentrations. Such levels of Ni and V may result to enhanced absorption by plants, which may bring about possible bioaccumulation in such

  1. Extractable hydrocarbons, nickel and vanadium contents of Ogbodo-Isiokpo oil spill polluted soils in Niger Delta, Nigeria.

    PubMed

    Osuji, Leo C; Adesiyan, Samuel O

    2005-11-01

    An oil spill polluted site at Ogbodo-Isiokpo in Ikwere Local Government Area of Rivers State in southern Nigeria, was identified for study following three successive reconnaissance surveys of oil fields in the Agbada west plain of Eastern Niger Delta. A sampling area of 200 m x 200 m was delimited at the oil spill impacted site using the grid technique and soils were collected at surface (0-15 cm) and subsurface (15-30 cm) depths from three replicate quadrats. A geographically similar, unaffected area, located 50 m adjacent to the polluted site, was chosen as a control (reference) site. Total extractable hydrocarbon contents of the polluted soils ranged from 3.02-4.54 and 1.60-4.20 mg/kg (no overlap in standard errors) at surface and subsurface depths respectively. The concentrations of two "diagnostic" trace heavy metals, nickel (Ni) and vanadium (V), which are normal constituents of crude oil, were also determined in the soils by atomic absorption spectrophotometric method after pre-extraction of cations with dithionite-citrate carbonate. Ni varied from 0.15 to 1.65 mg/kg in the polluted plots and from 0.18 to 0.82 mg/kg in the unpolluted plots; vanadium varied from 0.19 to 0.70 mg/kg in the polluted plots and from 0.14 to 0.38 mg/kg in the unpolluted plots. Ni and V were more enhanced (p < 0.05) in the oil-polluted soils, especially at subsurface depth. Whilst the oil spillage could be said to be indirectly responsible for the enhanced concentrations of nickel and vanadium via the injection and availability of the petroleum hydrocarbons that might have increased the activities of biodegradation on site, the physico-chemical properties of the soils and inherent mobility of metals, as well as the intense rainfall and flooding that characterized the period of study, may have also contributed, at least in part, to these enhanced concentrations. Such levels of Ni and V may result to enhanced absorption by plants, which may bring about possible bioaccumulation in such

  2. Carbon Stocks and Soil C Dynamics: an Investigation of C Sequestration Potential in a Eucalyptus grandis Plantation in Hawaii

    NASA Astrophysics Data System (ADS)

    Reeves, M. I.; Crow, S. E.; Yost, R.; Turn, S.

    2011-12-01

    hundreds to thousands of years. Previous data showed that in the surface 0-15 cm mineral soil, land use change from pasture to E. grandis resulted in a ≈ 30% decrease in total soil C stock specifically due to losses of the most labile soil C pools. This was expected, as grasses tend to input larger amounts of root biomass C in the surface soil. Therefore, it is hypothesized that soil under E. grandis is effective at storing C within fractions associated with longer term C sequestration. It is also hypothesized that soil under E. grandis will contain more C than the pasture soil in the deeper soil (30 cm to 1m) due to large differences in rooting depth. The rooting depth of E. grandis may account for a higher degree of organo-mineral association as there is more mineral surface area available for root exudate C to bind to in the rhizosphere. Furthermore, the lack of disturbance in the E. grandis plantation compared to grazed pastureland may lead to greater physical protection within aggregates; again leading to increased C sequestration.

  3. The 12 micron band of ethane: A spectral catalog from 765 cm(-1) to 900 cm(-1)

    NASA Technical Reports Server (NTRS)

    Atakan, A. K.; Blass, W. E.; Brault, J. W.; Daunt, S. J.; Halsey, G. W.; Jennings, D. E.; Reuter, D. C.; Susskind, J.

    1983-01-01

    The high resolution laboratory absorption spectrum of the 12 micro band of ethane gas is studied. The data were obtained using the McMath Solar Telescope 1 meter Fourier Transform interferometer at Kitt Peak National Observatory and tunable diode laser spectrometers at the University of Tennessee and NASA/Goddard Space Flight Center. Over 200 individual vibration rotation transitions were analyzed taking into account many higher order effects including torsional splitting. Line positions were reproduced to better than 0.001/cm. Both ground and upper state molecular constants were determined in the analysis. The experimental details, the analysis procedures and the results are addressed. A list of ethane transitions occurring near (14)CO2 laser lines needed for heterodyne searches for C2H6 in extraterrestrial sources is also included. A spectral catalog of the ethane nu sub g fundamental from 765/cm to 900/cm is provided. A high dispersion (1/cm 12 in.) plot of both the Kitt Peak interferometric data and a simulated spectrum with Doppler limited resolution, a table of over 8500 calculated transitions listed quantum number assignments, frequencies and intensities are provided.

  4. Remote sensing of soil moisture - Recent advances

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.

    1983-01-01

    Recent advancements in microwave remote sensing of soil moisture include a method for estimating the dependence of the soil dielectric constant on its texture, the use of a percent of field capacity to express soil moisture magnitudes independently of soil texture, methods of estimating soil moisture sampling depth, and models for describing the effect of surface roughness on microwave response in terms of surface height variance and horizontal correlation length, as well as the verification of radiative transfer model predictions of microwave emission from soils and methods for the estimation of vegetation effects on the microwave response to soil moisture. Such researches have demonstrated that it is possible to remotely sense soil moisture in the 0-5 cm soil surface layer, and simulation studies have indicated how remotely sensed surface soil moisture may be used to estimate evapotranspiration rates and root-zone soil moisture.

  5. 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

  6. Development of a 60 cm Magnetic Suspension System

    NASA Astrophysics Data System (ADS)

    Sawada, Hideo; Kunimasu, Tetsuya

    A 60cm Magnetic Suspension Balance System (MSBS), which has been developed in the National Aerospace Laboratory of Japan (NAL), is described in detail. Magnetic field in the MSBS is evaluated analytically and is compared with measured one. Available magnet kinds for the MSBS are selected analytically. The optimum ratio of diameter to length of cylindrical magnet for the MSBS is also evaluated. A model position sensing and the control systems are described with calibration test results. A model holding system is also shown, which is necessary for worker’s safety at suspending a large and massive model. The control system is presented and the measured model position during suspension is examined. The balance accuracy is examined and its error of drag force can be improved by restricting the calibration test to an expected drag range. Flow of the 60cm low-speed wind tunnel equipped with the MSBS is examined to be available for wind tunnel tests.

  7. 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.

  8. Lensing of 21-cm fluctuations by primordial gravitational waves.

    PubMed

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-25

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed. PMID:23003237

  9. 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.

  10. 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

  11. 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.

  12. 21 cm cosmology in the 21st century.

    PubMed

    Pritchard, Jonathan R; Loeb, Abraham

    2012-08-01

    Imaging the Universe during the first hundreds of millions of years remains one of the exciting challenges facing modern cosmology. Observations of the redshifted 21 cm line of atomic hydrogen offer the potential of opening a new window into this epoch. This will transform our understanding of the formation of the first stars and galaxies and of the thermal history of the Universe. A new generation of radio telescopes is being constructed for this purpose with the first results starting to trickle in. In this review, we detail the physics that governs the 21 cm signal and describe what might be learnt from upcoming observations. We also generalize our discussion to intensity mapping of other atomic and molecular lines. PMID:22828208

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    is 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.

  14. '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.

  15. 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.

  16. 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.

  17. Control of a 30 cm diameter mercury bombardment thruster

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Bechtel, R. T.

    1973-01-01

    Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide: (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

  18. Semi-Lagrangian shallow water modeling on the CM-5

    SciTech Connect

    Nadiga, B.T.; Margolin, L.G.; Smolarkiewicz, P.K.

    1995-09-01

    We discuss the parallel implementation of a semi-Lagrangian shallow-water model on the massively parallel Connection Machine CM-5. The four important issues we address in this article are (i) two alternative formulations of the elliptic problem and their relative efficiencies, (ii) the performance of two successive orders of a generalized conjugate residual elliptic solver, (iii) the time spent in unstructured communication -- an unavoidable feature of semi-Lagrangian schemes, and (iv) the scalability of the algorithm.

  19. 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.

  20. The 21 cm signature of cosmic string wakes

    SciTech Connect

    Brandenberger, Robert H.; Danos, Rebecca J.; Hernández, Oscar F.; Holder, Gilbert P. E-mail: rjdanos@physics.mcgill.ca E-mail: holder@physics.mcgill.ca

    2010-12-01

    We discuss the signature of a cosmic string wake in 21cm redshift surveys. Since 21cm surveys probe higher redshifts than optical large-scale structure surveys, the signatures of cosmic strings are more manifest in 21cm maps than they are in optical galaxy surveys. We find that, provided the tension of the cosmic string exceeds a critical value (which depends on both the redshift when the string wake is created and the redshift of observation), a cosmic string wake will generate an emission signal with a brightness temperature which approaches a limiting value which at a redshift of z+1 = 30 is close to 400 mK in the limit of large string tension. The signal will have a specific signature in position space: the excess 21cm radiation will be confined to a wedge-shaped region whose tip corresponds to the position of the string, whose planar dimensions are set by the planar dimensions of the string wake, and whose thickness (in redshift direction) depends on the string tension. For wakes created at z{sub i}+1 = 10{sup 3}, then at a redshift of z+1 = 30 the critical value of the string tension μ is Gμ = 6 × 10{sup −7}, and it decreases linearly with redshift (for wakes created at the time of equal matter and radiation, the critical value is a factor of two lower at the same redshift). For smaller tensions, cosmic strings lead to an observable absorption signal with the same wedge geometry.

  1. 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

  2. [Effect of Biochar Application on Soil Aggregates Distribution and Moisture Retention in Orchard Soil].

    PubMed

    An, Yan; Ji, Qiang; Zhao, Shi-xiang; Wang, Xu-dong

    2016-01-15

    Applying biochar to soil has been considered to be one of the important practices in improving soil properties and increasing carbon sequestration. In order to investigate the effects of biochar application on soil aggregates distribution and its organic matter content and soil moisture constant in different size aggregates, various particle-size fractions of soil aggregates were obtained with the dry-screening method. The results showed that, compared to the treatment without biochar (CK), the application of biochar reduced the mass content of 5-8 mm and < 0.25 mm soil aggregates at 0-10 cm soil horizon, while increased the content of 1-2 mm and 2-5 mm soil aggregates at this horizon, and the content of 1-2 mm aggregates significantly increased along with the rates of biochar application. The mean diameter of soil aggregates was reduced by biochar application at 0-10 cm soil horizon. However, the effect of biochar application on the mean diameter of soil aggregates at 10-20 cm soil horizon was not significant. Compared to CK, biochar application significantly increased soil organic carbon content in aggregates, especially in 1-2 mm aggregates which was increased by > 70% compared to CK. Both the water holding capacity and soil porosity were significantly increased by biochar application. Furthermore, the neutral biochar was more effective than alkaline biochar in increasing soil moisture. PMID:27078970

  3. [Effect of Biochar Application on Soil Aggregates Distribution and Moisture Retention in Orchard Soil].

    PubMed

    An, Yan; Ji, Qiang; Zhao, Shi-xiang; Wang, Xu-dong

    2016-01-15

    Applying biochar to soil has been considered to be one of the important practices in improving soil properties and increasing carbon sequestration. In order to investigate the effects of biochar application on soil aggregates distribution and its organic matter content and soil moisture constant in different size aggregates, various particle-size fractions of soil aggregates were obtained with the dry-screening method. The results showed that, compared to the treatment without biochar (CK), the application of biochar reduced the mass content of 5-8 mm and < 0.25 mm soil aggregates at 0-10 cm soil horizon, while increased the content of 1-2 mm and 2-5 mm soil aggregates at this horizon, and the content of 1-2 mm aggregates significantly increased along with the rates of biochar application. The mean diameter of soil aggregates was reduced by biochar application at 0-10 cm soil horizon. However, the effect of biochar application on the mean diameter of soil aggregates at 10-20 cm soil horizon was not significant. Compared to CK, biochar application significantly increased soil organic carbon content in aggregates, especially in 1-2 mm aggregates which was increased by > 70% compared to CK. Both the water holding capacity and soil porosity were significantly increased by biochar application. Furthermore, the neutral biochar was more effective than alkaline biochar in increasing soil moisture.

  4. A box corer 30 cm square and 4 m long

    NASA Astrophysics Data System (ADS)

    Foster Johnson, Richard

    1988-08-01

    To collect long, large-volume cores of diatomaceous sediment on the continental shelf off Namibia, we built a box corer that is 30 cm square and 4 m long. This paper describes the corer and the tools and procedures for sampling the covers. In terms of volume of sediment recovered in a single penetration, the corer may be among the largest ever used. The corer itself consists of a barrel with segments 20 cm long, a release mechanism at top and a thin fiberglass curtain at bottom. To support the large load of sediment without distortion, the curtain follows a semi-circular track, concave upward. During assembly and disassembly, the corer hangs vertically over the side, enabling it to operate from a relatively small ship. To sample the core, an extruding device pushes the sediment from each segment into boxes made of polyurethane foam. Ashore a specially designed jig helps slice these boxes into vertical slabs as thin as 1 cm. In the 6 days at sea that we had to test the corer and collect samples for the project, we took 9 cores, the longest of which was 3 m.

  5. 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.

  6. The wedge bias in reionization 21-cm power spectrum measurements

    NASA Astrophysics Data System (ADS)

    Jensen, Hannes; Majumdar, Suman; Mellema, Garrelt; Lidz, Adam; Iliev, Ilian T.; Dixon, Keri L.

    2016-02-01

    A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way, since it is limited to a wedge-shaped region in k∥, k⊥ space. However, the power spectrum is anisotropic owing to redshift-space distortions from peculiar velocities. Consequently, the 21-cm power spectrum measured in the foreground avoidance window - which samples only a limited range of angles close to the line-of-sight direction - differs from the full redshift-space spherically averaged power spectrum which requires an average over all angles. In this paper, we calculate the magnitude of this `wedge bias' for the first time. We find that the bias amplifies the difference between the real-space and redshift-space power spectra. The bias is strongest at high redshifts, where measurements using foreground avoidance will overestimate the redshift-space power spectrum by around 100 per cent, possibly obscuring the distinctive rise and fall signature that is anticipated for the spherically averaged 21-cm power spectrum. In the later stages of reionization, the bias becomes negative, and smaller in magnitude (≲20 per cent).

  7. 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.

  8. BRIGHT SOURCE SUBTRACTION REQUIREMENTS FOR REDSHIFTED 21 cm MEASUREMENTS

    SciTech Connect

    Datta, A.; Bowman, J. D.; Carilli, C. L.

    2010-11-20

    The H I 21 cm transition line is expected to be an important probe into the cosmic dark ages and epoch of reionization. Foreground source removal is one of the principal challenges for the detection of this signal. This paper investigates the extragalactic point source contamination and how accurately bright sources ({approx}>1 Jy) must be removed in order to detect 21 cm emission with upcoming radio telescopes such as the Murchison Widefield Array. We consider the residual contamination in 21 cm maps and power spectra due to position errors in the sky model for bright sources, as well as frequency-independent calibration errors. We find that a source position accuracy of 0.1 arcsec will suffice for detection of the H I power spectrum. For calibration errors, 0.05% accuracy in antenna gain amplitude is required in order to detect the cosmic signal. Both sources of subtraction error produce residuals that are localized to small angular scales, k{sub perpendicular} {approx}> 0.05 Mpc{sup -1}, in the two-dimensional power spectrum.

  9. High angular resolution cosmic X-ray astronomy observations in the energy range 0.15-2 keV and XUV observations of nearby stars from an attitude controlled rocket

    NASA Technical Reports Server (NTRS)

    Garmire, G. P.

    1974-01-01

    The construction of a two dimensional focusing Wolter Type I mirror system for X-ray and XUV astronomical observations from an Astrobee F sounding rocket is described. The mirror design goal will have a one degree field, a 20-arc seconds resolution, an effective area of about 50 sq cm at 1 keV and 10 sq cm at 0.25 keV on axis. A star camera provides aspect data to about 15-arc seconds. Two detectors are placed at the focus with an interchange mechanism to allow a detector change during flight. The following specific developments are reported: (1) position sensitive proportional counter development; (2) channel plate multiplier development; (3) telescope mirror development and payload structure; (4) Australian rocket flight results; (5) Comet Kohoutek He I observation; and (6) Vela, Puppis A, and Gem-Mon bright patch observations.

  10. [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. PMID:24558863

  11. 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.

  12. Unraveling the Degradation Process of LiNi0.8Co0.15Al0.05O2 Electrodes in Commercial Lithium Ion Batteries by Electronic Structure Investigations.

    PubMed

    Kleiner, Karin; Melke, Julia; Merz, Michael; Jakes, Peter; Nagel, Peter; Schuppler, Stefan; Liebau, Verena; Ehrenberg, Helmut

    2015-09-01

    The degradation of LiNi0.8Co0.15Al0.05O2 (LNCAO) is reflected by the electrochemical performance in the fatigued state and correlated with the redox behavior of these cathodes. The detailed electrochemical performance of these samples is investigated by galvanostatic and voltammetric cycling as well as with the galvanostatic intermittent titration technique (GITT). Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to investigate the oxidation state of all three materials at the Ni L2,3, O K, and Co L2,3 edges at five different states of charge. Surface and more bulklike properties are distinguished by total electron yield (TEY) and fluorescence yield (FY) measurements. The electrochemical investigations revealed that the changes in the cell performance of the differently aged materials can be explained by considering the reaction kinetics of the intercalation/deintercalation process. The failure of the redox process of oxygen and nickel at low voltages leads to a significant decrease of the reaction rates in the fatigued cathodes. The accompanied cyclic voltammogram (CV) peaks appear as two peaks because of the local minimum of the reaction rate, although it is one peak in the CV of the calendarically aged LNCAO. The absence of the oxidation/reduction process at low voltages can be traced back to changes in the surface morphology (formation of a NiO-like structure). Further consequences of these material changes are overpotentials, which lead to capacity losses of up to 30% (cycled with a C/3 rate). PMID:26281920

  13. 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.

  14. 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.

  15. 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. PMID:23762259

  16. 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.

  17. 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

  18. 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).

  19. 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.

  20. 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.

  1. 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. PMID:27343077

  2. 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

  3. 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

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

    PubMed

    Kirkby, Clive A; 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

  5. 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.

  6. 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

  7. 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

  8. The Transition to ICD-10-CM: Challenges for Pediatric Practice

    PubMed Central

    Zaman, Jeffrey; Nam, Hannah; Chae, Sae-Rom; Williams, Lauren; Mathew, Gina; Burton, Michael; Li, Jiarong “John”; Lussier, Yves A.

    2014-01-01

    BACKGROUND AND OBJECTIVES: Diagnostic codes are used widely within health care for billing, quality assessment, and to measure clinical outcomes. The US health care system will transition to the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM), in October 2015. Little is known about how this transition will affect pediatric practices. The objective of this study was to examine how the transition to ICD-10-CM may result in ambiguity of clinical information and financial disruption for pediatricians. METHODS: Using a statewide data set from Illinois Medicaid specified for pediatricians, 2708 International Classification of Diseases, Ninth Revision, Clinical Modification, diagnosis codes were identified. Diagnosis codes were categorized into 1 of 5 categories: identity, class-to-subclass, subclass-to-class, convoluted, and no translation. The convoluted and high-cost diagnostic codes (n = 636) were analyzed for accuracy and categorized into “information loss,” “overlapping categories,” “inconsistent,” and “consistent.” Finally, reimbursement by Medicaid was calculated for each category. RESULTS: Twenty-six percent of pediatric diagnosis codes are convoluted, which represents 21% of Illinois Medicaid pediatric patient encounters and 16% of reimbursement. The diagnosis codes represented by information loss (3.6%), overlapping categories (3.2%), and inconsistent (1.2%) represent 8% of Medicaid pediatric reimbursement. CONCLUSIONS: The potential for financial disruption and administrative errors from 8% of reimbursement diagnosis codes necessitates special attention to these codes in preparing for the transition to ICD-10-CM for pediatric practices. PMID:24918217

  9. Multiple precursors of secondary mineralogical assemblages in CM chondrites

    NASA Astrophysics Data System (ADS)

    Pignatelli, Isabella; Marrocchi, Yves; Vacher, Lionel. G.; Delon, RéMi; Gounelle, Matthieu

    2016-04-01

    We report a petrographic and mineralogical survey of tochilinite/cronstedtite intergrowths (TCIs) in Paris, a new CM chondrite considered to be the least altered CM identified to date. Our results indicate that type-I TCIs consist of compact tochilinite/cronstedtite rims surrounding Fe-Ni metal beads, thus confirming kamacite as the precursor of type-I TCIs. In contrast, type-II TCIs are characterized by complex compositional zoning composed of three different Fe-bearing secondary minerals: from the outside inwards, tochilinite, cronstedtite, and amakinite. Type-II TCIs present well-developed faces that allow a detailed morphological analysis to be performed in order to identify the precursors. The results demonstrate that type-II TCIs formed by pseudomorphism of the anhydrous silicates, olivine, and pyroxene. Hence, there is no apparent genetic relationship between type-I and type-II TCIs. In addition, the complex chemical zoning observed within type-II TCIs suggests that the alteration conditions evolved dramatically over time. At least three stages of alteration can be proposed, characterized by alteration fluids with varying compositions (1) Fe- and S-rich fluids; (2) S-poor and Fe- and Si-rich fluids; and (3) S- and Si-poor, Fe-rich fluids. The presence of unaltered silicates in close association with euhedral type-II TCIs suggests the existence of microenvironments during the first alteration stages of CM chondrites. In addition, the absence of Mg-bearing secondary minerals in Paris TCIs suggests that the Mg content increases during the course of alteration.

  10. [Carbon source utilization characteristics of microbial communities in a petroleum-contaminated soil in Daqing Oil Field, Northeast China].

    PubMed

    Yue, Bing-Bing; Li, Xin; Ren, Fang-Fei; Meng, Fan-Juan; Yin, Peng-Da; Zhang, Hui-Hui; Sun, Guang-Yu

    2011-12-01

    By using Biolog technique, this paper studied the carbon source utilization characteristics of microbial communities in different layers (0-10 cm, 10-20 cm, and 20-30 cm) of a petroleum-contaminated soil near an oil well having exploited for 36 years in Daqing Oil Field. Petroleum contamination enhanced the metabolic activity of the soil microbial communities obviously. In the three layers of the petroleum-contaminated soil, the metabolic activity of the microbes was higher than that of the control, and there existed significant differences between different layers of the petroleum-contaminated soil. The carbon source metabolic capacity of the microbes in different layers of the petroleum-contaminated soil was in the order of 20-30 cm > 10-20 cm > 0-10 cm. Petroleum contamination made the kinds of soil carbon source and the metabolic diversity of soil microbes increased, being more obvious in 10-20 cm and 20-30 cm soil layers but less change in 0-10 cm soil layer. In the contaminated soil, the majority of the carbon sources utilized by the microbes in 10-20 cm soil layer were carbohydrates instead of the carboxylic acids in non-contaminated soil, whereas the majority of the carbon substrates utilized in 20-30 cm soil layer were carboxylic acids. All the results suggested that petroleum-contaminated soil had its unique microbial community structure and peculiar microbial carbon source utilization characteristics.

  11. Performance of 30-cm ion thrusters with dished accelerator grids

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Thirteen sets of dished accelerator grids were tested on five different 30-cm diameter bombardment thrustors to evaluate the effects of grid geometry variations on thrustor discharge chamber performance. The dished grid parameters varied were: grid-to-grid spacing, screen and accelerator grid hole-diameter, screen and accelerator open area fraction, compensation for beam divergence losses, and accelerator grid thickness. Also investigated were the effects on discharge chamber performance of main magnetic field changes, magnetic baffle current cathode pole piece length and cathode position.

  12. 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.

  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. Affordable échelle spectroscopy with a 60 cm telescope

    NASA Astrophysics Data System (ADS)

    Pribulla, T.; Garai, Z.; Hambálek, L.; Kollár, V.; Komžík, R.; Kundra, E.; Nedoroščík, J.; Sekeráš, M.; Vaňko, M

    2015-09-01

    A new fiber-fed spectrograph was installed at the 60 cm telescope of the Stará Lesná Observatory. The article presents tests of its performance (spectral resolution, signal-to-noise ratio, radial-velocity stability) and reports observations of selected variable stars and exoplanet host stars. First test observations show that the spectrograph is an ideal tool to observe bright eclipsing and spectroscopic binaries but also symbiotic and nova-like stars. The radial-velocity stability (60-80 ms-1) is sufficient to study spectroscopic binaries and to detect easily the orbital motion of hot-Jupiter extrasolar planets around bright stars.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Radiated and conducted EMI from a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Whittlesey, A. C.; Peer, W.

    1981-01-01

    In order to properly assess the interaction of a spacecraft with the EMI environment produced by an ion thruster, the EMI environment was characterized. Therefore, radiated and conducted emissions were measured from a 30-cm mercury ion thruster. The ion thruster beam current varied from zero to 2.0 amperes and the emissions were measured from 5 KHz to 200 MHz. Several different types of antennas were used to obtain the measurements. The various measurements that were made included: magnetic field due to neutralizer/beam current loop; radiated electric fields of thruster and plume; and conducted emissions on arc discharge, neutralizer keeper and magnetic baffle lines.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    PubMed

    Reynolds, T D; Laundré, 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.

  9. 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.

  10. Characterization of extractable soil organic matter pools from African Dark Earths (AfDE): A case study in historical biochar and organic waste amendments

    NASA Astrophysics Data System (ADS)

    Fujiu, Manna; Plante, Alain; Ohno, Tsutomu; Solomon, Dawit; Lehmann, Johannes; Fraser, James; Leach, Melissa; Fairhead, James

    2014-05-01

    Anthropogenic Dark Earths are soils generated through long-term human inputs of organic and pyrogenic materials. These soils were originally discovered in the Amazon, and have since been found in Australia and in this case in Africa. African Dark Earths (AfDE) are black, highly fertile and carbon-rich soils that were formed from the original highly-weathered infertile yellowish to red Oxisols and Ultisols through an extant but hitherto overlooked climate-smart sustainable soil management system that has long been an important feature of the indigenous West African agricultural repertoire. Studies have demonstrated that ADE soils in general have significantly different organic matter properties compared to adjacent non-DE soils, largely attributable to the presence of high concentrations of ash-derived carbon. Quantification and characterization of bulk soil organic matter of several (n=11) AfDE and non-AfDE pairs of surface (0-15 cm) soils using thermal analysis techniques (TG-DSC-EGA) confirmed substantial differences in SOM composition and the presence of pyrogenic C. Such pyrogenic organic matter is generally considered recalcitrant or relatively stable, but the goal of the current study was to characterize the presumably labile, more rapidly cycling, pools of C in AfDEs through the characterization of hot water- and pyrophosphate-extractable fractions, referred to as HWEOC and PyroC respectively. Extracts were analyzed for carbon content, as well as composition using fluorescence (EEM/PARAFAC) and high resolution mass spectrometry (FTICR-MS). The amount of extractable C as a proportion of total soil C was relatively low: less than ~0.8% for HWEOC and 2.8% for PyroC. The proportion of HWEOC did not differ (P = 0.18, paired t-test) between the AfDE and the non-AfDE soils, while the proportions of PyroC were significantly larger (P = 0.001) in the AfDE soils compared to the non-AfDE soils. Preliminary analysis of the EEM/PARAFAC data suggests that AfDE samples had

  11. 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 ...

  12. The amino acid and hydrocarbon contents of the Paris meteorite, the most primitive CM chondrite

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The Paris meteorite is reported to be the least aqueously altered CM chondrite [1,2], and to have experienced only weak thermal metamorphism [2-5]. The IR spectra of some of Paris' fragments suggest a primitive origin for the organic matter in this meteorite, similar to the spectra from solid-state materials in molecular clouds [6]. Most of the micron-sized organic particles present in the Paris matrix exhibit 0 < δD <2000‰ [7,8]. In order to understand the effect of aqueous alteration and thermal metamorphism on the abundance and distribution of meteoritic soluble organic matter, we have analyzed for the first time the amino acid and hydrocarbon contents of the Paris meteorite [9]. Extensive aqueous alteration in the parent body of carbonaceous meteorites may result in the decomposition of α-amino acids and the synthesis of β- and γ-amino acids. When plotted with several CM chondrites, Paris has the lowest relative abundance of β-alanine/glycine (0.15) for a CM chondrite, which fits with the relative abundance of β-alanine/glycine increasing with increasing aqueous alteration [10,11]. In addition, our results show that the isovaline detected in this meteorite is racemic (D/L= 0.99 ± 0.08; L-enantiomer excess (%) = 0.35 ± 0.5; corrected D/L = 1.03; corrected L-enantiomer excess (%) = -1.4 ± 2.6). Although aqueous alteration does not create by itself an isovaline asymmetry, it may amplify a small enantiomeric excess. Therefore, our data may support the hypothesis that aqueous alteration is responsible for the high L-enantiomer excess of isovaline observed in the most aqueously altered carbonaceous meteorites [12,13]. Paris has n-alkanes ranging from C16 to C25 and 3- to 5-ring non-alkylated polycyclic aromatic hydrocarbons (PAHs). The lack of alkylated PAHs in Paris seems to be related to the low degree of aqueous alteration on its parent body [9,14]. The extra-terrestrial aliphatic and aromatic hydrocarbon content of Paris may have an interstellar origin

  13. 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 num