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Sample records for surface soil 0-5

  1. Charge transfer effects on the Fermi surface of Ba0.5K 0.5Fe2As2

    KAUST Repository

    Nazir, Safdar

    2011-01-31

    Ab-initio calculations within density functional theory are performed to obtain a more systematic understanding of the electronic structure of iron pnictides. As a prototypical compound we study Ba0.5K 0.5Fe2As2 and analyze the changes of its electronic structure when the interaction between the Fe2As 2 layers and their surrounding is modified. We find strong effects on the density of states near the Fermi energy as well as the Fermi surface. The role of the electron donor atoms in iron pnictides thus cannot be understood in a rigid band picture. Instead, the bonding within the Fe2As 2 layers reacts to a modified charge transfer from the donor atoms by adapting the intra-layer Fe-As hybridization and charge transfer in order to maintain an As3- valence state. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Extracting the near surface stoichiometry of BiFe0.5Mn0.5O3 thin films; a finite element maximum entropy approach

    NARCIS (Netherlands)

    Song, F.; Monsen, A.; Li, Z. S.; Choi, E. -M.; MacManus-Driscoll, J. L.; Xiong, J.; Jia, Q. X.; Wahlstrom, E.; Wells, J. W.

    2012-01-01

    The surface and near-surface chemical composition of BiFe0.5Mn0.5O3 has been studied using a combination of low photon energy synchrotron photoemission spectroscopy, and a newly developed maximum entropy finite element model from which it is possible to extract the depth dependent chemical compositi

  3. Structural, Electronic and Optical Properties of KTa0.5Nb0.5O3 Surface: A First-Principles Study

    Institute of Scientific and Technical Information of China (English)

    SUN Hong-Guo; ZHOU Zhong-Xiang; YUAN Cheng-Xun; YANG Wen-Long; WANG He

    2012-01-01

    The crystal surface properties of potassium tantalite niobate,KTa0.5Nb0.5O3 (KTN),are studied with firstprinciples calculation based on the density functional theory (DFT).Generalized gradient approximation (GGA) functional analysis is also employed by using CASTEP software.The explanations for the differences of the ferroelectric and piezoelectric properties between the bulk and surface of the material are provided.The DFT with GGA is used to determine the structure and to calculate the electronic and optical properties of the chemically ordered KTa0.5Nb0.5O3 crystal (100),(110) and (111) surfaces.The results show that the surface properties are different from the bulk properties.The data obtained agree with the expected values and can serve as guidance for future experimental studies in the fields of photorefraction and nonlinear optics.%The crystal surface properties of potassium tantalite niobate, Ktao.5Nbo.5O3 (KTN), are studied with first-principles calculation based on the density functional theory (DFT). Generalized gradient approximation (GGA) functional analysis is also employed by using CASTEP software. The explanations for the differences of the ferroelectric and piezoelectric properties between the bulk and surface of the material are provided. The DFT with GGA is used to determine the structure and to calculate the electronic and optical properties of the chemically ordered Ktao.sNbo.5O3 crystal (100), (110) and (111) surfaces. The results show that the surface properties are different from the bulk properties. The data obtained agree with the expected values and can serve as guidance for future experimental studies in the Gelds of photorefraction and nonlinear optics.

  4. Surface spin glass and exchange bias effect in Sm0.5Ca0.5MnO3 manganites nano particles

    Directory of Open Access Journals (Sweden)

    S. K. Giri

    2011-09-01

    Full Text Available In this letter, we report that the charge/orbital order state of bulk antiferromagnetic Sm0.5Ca0.5MnO3 is suppressed and confirms the appearance of weak ferromagnetism below 65 K followed by a low temperature spin glass like transition at 41 K in its nano metric counterpart. Exchange anisotropy effect has been observed in the nano manganites and can be tuned by the strength of the cooling magnetic field (Hcool. The values of exchange fields (HE, coercivity (HC, remanence asymmetry (ME and magnetic coercivity (MC are found to strongly depend on cooling magnetic field and temperature. HE increases with increasing Hcool but for larger Hcool, HE tends to decrease due to the growth of ferromagnetic cluster size. Magnetic training effect has also been observed and it has been analyzed thoroughly using spin relaxation model. A proposed phenomenological core-shell type model is attributed to an exchange coupling between the spin-glass like shell (surrounding and antiferromagnetic core of Sm0.5Ca0.5MnO3 nano manganites mainly on the basis of uncompensated surface spins. Results suggest that the intrinsic phase inhomogeneity due to the surface effects of the nanostructured manganites may cause exchange anisotropy, which is of special interests for potential application in multifunctional spintronic devices.

  5. Ferromagnetism of Na0.5Bi0.5TiO3 (1 0 0) surface with O2 adsorption

    Science.gov (United States)

    Ju, Lin; Xu, Tongshuai; Zhang, Yongjia; Shi, Changmin; Sun, Li

    2017-08-01

    Na0.5Bi0.5TiO3 (NBT) nanocrystalline powders prepared by sol-gel method with annealing at 900 °C in air 1 h present room-temperature ferromagnetism (FM). The subsequent annealing in vacuum at 900 °C for 30 min weakens the room-temperature FM, while subsequent treatments in oxygen atmosphere at room-temperature enhances the room-temperature FM, indicating that the room-temperature FM may be induced by the adsorbed oxygen on the NBT nanoparticle surface. The adsorption of O2 molecule on the NBT (1 0 0) surface is studied by using density functional theory within local density approximation plus on-site effect method. The physisorption of configuration R5 is the most stable, whereas the chemisorption of O2 is unfavorable at all adsorption sites. The physisorbed O2 molecule on the NBT (1 0 0) surface with a magnetic moment (MM) closes to that for an isolated O2 molecule. The magnetism of configuration R5 is mainly from the O p orbitals. The stable ferromagnetic coupling mechanism is the direct exchange interaction between the nearest-neighbor O2 molecules adsorbed on the surface. The adsorption of O2 molecule on ferroelectric materials may be a promising approach to achieve multiferroic materials.

  6. Charge transfer effects on the Fermi surface of Ba{sub 0.5}K{sub 0.5}Fe{sub 2}As{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, S.; Zhu, Z.Y.; Schwingenschloegl, U. [KAUST, PSE Division, Thuwal 23955-6900 (Saudi Arabia)

    2011-03-15

    Ab-initio calculations within density functional theory are performed to obtain a more systematic understanding of the electronic structure of iron pnictides. As a prototypical compound we study Ba{sub 0.5}K{sub 0.5}Fe{sub 2}As{sub 2} and analyze the changes of its electronic structure when the interaction between the Fe{sub 2}As{sub 2} layers and their surrounding is modified. We find strong effects on the density of states near the Fermi energy as well as the Fermi surface. The role of the electron donor atoms in iron pnictides thus cannot be understood in a rigid band picture. Instead, the bonding within the Fe{sub 2}As{sub 2} layers reacts to a modified charge transfer from the donor atoms by adapting the intra-layer Fe-As hybridization and charge transfer in order to maintain an As{sup 3-} valence state. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Observation of selective surface element substitution in FeTe0.5Se0.5 superconductor thin film exposed to ambient air by synchrotron radiation spectroscopy

    Science.gov (United States)

    Zhang, Nian; Liu, Chen; Zhao, Jia-Li; Lei, Tao; Wang, Jia-Ou; Qian, Hai-Jie; Wu, Rui; Yan, Lei; Guo, Hai-Zhong; Ibrahim, Kurash

    2016-09-01

    A systematic investigation of oxidation on a superconductive FeTe0.5Se0.5 thin film, which was grown on Nb-doped SrTiO3 (001) by pulsed laser deposition, has been carried out. The sample was exposed to ambient air for one month for oxidation. Macroscopically, the exposed specimen lost its superconductivity due to oxidation. The specimen was subjected to in situ synchrotron radiation photoelectron spectroscopy (PES) and x-ray absorption spectroscopy (XAS) measurements following cycles of annealing and argon ion etching treatments to unravel what happened in the electronic structure and composition after exposure to air. By the spectroscopic measurements, we found that the as-grown FeTe0.5Se0.5 superconductive thin film experienced an element selective substitution reaction. The oxidation preferentially proceeds through pumping out the Te and forming Fe-O bonds by O substitution of Te. In addition, our results certify that in situ vacuum annealing and low-energy argon ion etching methods combined with spectroscopy are suitable for depth element and valence analysis of layered structure superconductor materials. Project supported by the Chinese Academy of Sciences (Grant No. 1G2009312311750101) and the National Natural Science Foundation of China (Grant Nos. 11375228, 11204303, and U1332105).

  8. Improved electrochemical properties of LiFe0.5Mn0.5PO4/C composite materials via a surface coating process

    Science.gov (United States)

    Yang, Chun-Chen; Hung, Yen-Wei; Lue, Shingjiang Jessie

    2016-09-01

    In this work, a LiFe0.5Mn0.5PO4/C (LFMP/C) material was prepared by a simple solid-state ball-mill method by using LiH2PO4, γ-MnO2, and hollow α-Fe2O3 nano-sized materials. Both γ-MnO2 and hollow α-Fe2O3 were synthesized by a hydrothermal process. LFMP/C composites coated with different amounts (1-3wt%) of Li4Ti5O12 (LTO) were synthesized by a sol-gel method. Their typical properties are studied using X-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, transmission electron microscopy, the AC impedance method, and the galvanostatic charge-discharge method. The results revealed that a 1 wt%-LTO-coated LFMP/C composite shows the highest performance among all LFMP/C composite samples. The long-term cycling performance of the LFMP/C composite improves considerably when the LTO ionic conductor is applied on it. Moreover, the 1 wt%-LTO-coated LFMP/C composite, which has the lowest fading rate, maintains high cycling stability at 1 C (141 mAh g-1) and 10 C (133 mAh g-1) at 55 °C after 100 cycles; by contrast, a bare LFMP/C sample, which demonstrates the highest fading rate, exhibits an unfavorable life cycle, and its discharge capacity decreases rapidly. The ionic conductor coating thus improves the high-temperature performance of LFMP/C composites. A LFMP/C-KS6/SiO2 full cell is assembled and tested.

  9. Surface Tuning of La0.5Sr0.5CoO3 Perovskite Catalysts by Acetic Acid for NOx Storage and Reduction.

    Science.gov (United States)

    Peng, Yue; Si, Wenzhe; Luo, Jinming; Su, Wenkang; Chang, Huazhen; Li, Junhua; Hao, Jiming; Crittenden, John

    2016-06-21

    Selective dissolution of perovskite A site (A of ABO3 structure) was performed on the La1 - xSrxCoO3 catalysts for the NOx storage and reduction (NSR) reaction. The surface area of the catalysts were enhanced using dilute HNO3 impregnation to dissolve Sr. Inactive SrCO3 was removed effectively within 6 h, and the catalyst preserved the perovskite framework after 24 h of treatment. The tuned catalysts exhibited higher NSR performance (both NOx storage and NO-to-NO2 oxidation) under lean-burn and fuel-rich cycles at 250 °C. Large amounts of NOx adsorption were due to the increase of nitrate/nitrite species bonding to the A site and the growth of newly formed monodentate nitrate species. Nitrate species were stored stably on the partial exposed Sr(2+) cations. These exposed Sr(2+) cations played an important role on the NOx reduction by C3H6. High NO-to-NO2 oxidation ability was due to the generation of oxygen defects and Co(2+)-Co(3+) redox couples, which resulted from B-site exsolution induced by A-site dissolution. Hence, our method is facile to modify the surface structures of perovskite catalysts and provides a new strategy to obtain highly active catalysts for the NSR reaction.

  10. Fermi Surface Topology of Na0.5CoO2 from the Hybrid Density Functional

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhao-Ying; XIANG Hong-Jun; YANG Jin-Long

    2005-01-01

    @@ The Fermi surface topology of Na0.5CoO2 is studied using the hybrid density functional theory. We first study a single (CoO2)0.5- layer model with the percentage of the nonlocal Hartree-Fock exchange changing from 0% to 20%. The results show that only when the mixed nonlocal Hartree-Fock exchange is between 1% and 5%, the Fermi surface topology is similar to the experimental one. With 3% HF exchange in the hybrid density functional,considering the effects of Na ions in the Na0.sCoO2 system, we find that the Fermi surface is split to double holes and small gaps open near the intersections between the Brillouin zone and the Fermi surface. Our results show that both the amounts of the nonlocal Hartree-Fock exchange in the hybrid density functional and the Na ions have much influence on the Fermi surface topology.

  11. Half-metallic properties of the Co 2Ti 1- xFe xGa Heusler alloys and Co 2Ti 0.5Fe 0.5Ga (0 0 1) surface

    Science.gov (United States)

    Ahmadian, F.; Boochani, A.

    2011-07-01

    Electronic and magnetic properties of the bulk Co 2Ti 1- xFe xGa Heusler alloys and Co 2Ti 0.5Fe 0.5Ga (0 0 1) surfaces are studied within the framework of density functional theory using the augmented plane wave plus local orbital (APW+lo) approach. It will be shown that all alloys have the spin polarization of the ideal 100% value except the Co 2FeGa alloy with spin polarization about 98%. Co 2Ti 0.5Fe 0.5Ga is an example that is stable against the effects destroying the half-metallicity due to the position of the Fermi energy ( EF) in the middle of the minority band gap. The phase diagram obtained by ab-initio atomistic thermodynamics shows that in the higher limit of μGa three surfaces of FeGa, TiGa and TiFeGa are accessible in the Co 2Ti 0.5Fe 0.5Ga alloy but on decreasing μGa, the accessible region gradually moves towards FeGa termination. It is discussed that, at the ideal surfaces, half-metallicity of the alloy is lost, although the TiGa surface keeps high spin polarization (about 95%).

  12. Nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3−δ} synthesized using a chelating route for use in IT-SOFC cathodes: Microstructure, surface chemistry and electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Scurtu, Rares [“IlieMurgulescu” Institute of Physical Chemistry, Romanian Academy, 202 SplaiulIndependentei, 060021 Bucharest (Romania); Romania National Institute for Research and Development in Microtechnologies(IMT), 023573 Bucharest (Romania); Somacescu, Simona, E-mail: ssimona@icf.ro [“IlieMurgulescu” Institute of Physical Chemistry, Romanian Academy, 202 SplaiulIndependentei, 060021 Bucharest (Romania); Calderon-Moreno, Jose Maria; Culita, Daniela [“IlieMurgulescu” Institute of Physical Chemistry, Romanian Academy, 202 SplaiulIndependentei, 060021 Bucharest (Romania); Bulimestru, Ion; Popa, Nelea; Gulea, Aurelian [Faculty of Chemistry and Chemical Technology State University of Moldova 60 Mateevici, Chisinau MD 2009 Republic of Moldova (Moldova, Republic of); Osiceanu, Petre [“IlieMurgulescu” Institute of Physical Chemistry, Romanian Academy, 202 SplaiulIndependentei, 060021 Bucharest (Romania)

    2014-02-15

    Nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3−δ} powders were synthesized by a chelating route using different polyfunctional H{sub x}APC acids (APC=aminopolycarboxylate; x=3, 4, 5). Different homologous aminopolycarboxylic acids, namely nitrilotriacetic (H{sub 3}nta), ethylenediaminetetraacetic (H{sub 4}edta), 1,2-cyclohexanediaminetetracetic (H{sub 4}cdta) and diethylenetriaminepentaacetic (H{sub 5}dtpa) acid, were used as chelating agents to combine Sm, Sr, Co elements into a perovskite structure. The effects of the chelating agents on the crystalline structure, porosity, surface chemistry and electrical properties were investigated. The electrical properties of the perovskite-type materials emphasized that their conductivities in the temperature range of interest (600–800 °C) depend on the nature of the precursors as well as on the presence of a residual Co oxide phase as shown by XRD and XPS analysis. The surface chemistry and the surface stoichiometries were determined by XPS revealing a complex chemical behavior of Sr that exhibits a peculiar “surface phase” and “bulk phase” chemistry within the detected volume (<10 nm). - Graphical abstract: Synthesis of nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3−δ} powders by a chelating route and the investigation of the microstructure, surface chemistry and electrical properties. Display Omitted - Highlights: • Nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3−δ} obtained by a chelating synthesis route. • Cubic perovskite structures with crystallite sizes ∼23±2 nm. • The porous nature revealed by N{sub 2} adsorption/desorption (BET). • The surface chemistry and the surface stoichiometries highlighted by XPS. • A complex chemical behavior of Sr exhibits a peculiar “surface phase” and “bulk phase” chemistry.

  13. In situ study of electrochemical activation and surface segregation of the SOFC electrode material La0.75Sr0.25Cr0.5Mn0.5O(3±δ).

    Science.gov (United States)

    Huber, Anne-Katrin; Falk, Mareike; Rohnke, Marcus; Luerssen, Bjoern; Gregoratti, Luca; Amati, Matteo; Janek, Jürgen

    2012-01-14

    Mixed-conducting perovskite-type electrodes which are used as cathodes in solid oxide fuel cells (SOFCs) exhibit pronounced performance improvement after cathodic polarization. The current in situ study addresses the mechanism of this activation process which is still unknown. We chose the new perovskite-type material La(0.75)Sr(0.25)Cr(0.5)Mn(0.5)O(3±δ) which is a potential candidate for use in symmetrical solid oxide fuel cells (SFCs). We prepared La(0.75)Sr(0.25)Cr(0.5)Mn(0.5)O(3±δ) thin film model electrodes on YSZ (111) single crystals by pulsed laser deposition (PLD). Impedance spectroscopy (EIS) measurements show that the kinetics of these electrodes can be drastically improved by applying a cathodic potential. To understand the origin of the enhanced electrocatalytic activity the surfaces of operating LSCrM electrodes were studied in situ (at low pressure) with spatially resolving X-ray photoelectron spectroscopy (μ-ESCA, SPEM) and quasi static secondary ion mass spectrometry (ToF-SIMS) after applying different electrical potentials in the SIMS chamber. We observed that the electrode surfaces which were annealed at 600 °C are enriched significantly in strontium. Subsequent cathodic polarization decreases the strontium surface concentration while anodic polarization increases the strontium accumulation at the electrode surface. We propose a mechanism based on the reversible incorporation of a passivating SrO surface phase into the LSCrM lattice to explain the observed activation/deactivation process.

  14. Adhesion of composite to enamel and dentin surfaces irradiated by IR laser pulses of 0.5-35 micros duration.

    Science.gov (United States)

    Staninec, Michal; Gardner, Andrew K; Le, Charles Q; Sarma, Anupama V; Fried, Daniel

    2006-10-01

    The characteristics of laser-treated tooth surfaces depend on the laser wavelength, pulse duration, spatial and temporal laser beam quality, incident fluence, surface roughness, and the presence of water during irradiation. Ablated surfaces are most commonly restored with adhesive dental materials and the characteristics of the ablated surfaces influence adhesion of restorative materials. Previous studies suggest that high bond strengths can be achieved using shorter laser pulses that minimize peripheral thermal damage. In this study, Er:YSGG, Er:YAG, and CO(2) lasers were used at irradiation intensities sufficient to simulate efficient clinical caries removal to uniformly irradiate bovine enamel and human dentin surfaces using a motion control system with a microprocessor-controlled water spray. The degree of spatial overlap of adjacent pulses was varied so as to investigate the influence of irradiation uniformity and surface roughness on the bond strength. Composite resin was bonded to the irradiated surfaces and shear bond tests were used to obtain bond strengths in MPa. The highest results were obtained using the Er:YAG pulses with pulse durations less than 35 mus without the necessity for postirradiation acid etching. Some of these groups were not significantly different from nonirradiated, acid-etch-only positive control groups.

  15. Fabrication and qualification of roughness reference samples for industrial testing of surface roughness levels below 0.5 nm Sq

    Science.gov (United States)

    Faehnle, O.; Langenbach, E.; Zygalsky, F.; Frost, F.; Fechner, R.; Schindler, A.; Cumme, M.; Biskup, H.; Wünsche, C.; Rascher, R.

    2015-08-01

    Applying reactive ion beam etching (RIBE) processes at the Leibniz Institute of Surface Modification (IOM), several reference samples to be used in industry for calibrating of roughness testing equipment have been generated with the smoothest sample featuring 0.1 nm rms Sq. Subsequently these reference samples have been measured cross-site applying atomic force microscopy (AFM), white light interferometry (WLI), Nomarski1 microscopy (NM) and scatterometry (iTIRM2) determining the appropriate range of measurable rms surface roughness for each industrial measuring device.

  16. High potential durability of LiNi0.5Mn1.5O4 electrodes studied by surface sensitive X-ray absorption spectroscopy

    Science.gov (United States)

    Kawaura, Hiroyuki; Takamatsu, Daiko; Mori, Shinichiro; Orikasa, Yuki; Sugaya, Hidetaka; Murayama, Haruno; Nakanishi, Kouji; Tanida, Hajime; Koyama, Yukinori; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi

    2014-01-01

    Phenomena at electrode/electrolyte interface of LiNi0.5Mn1.5O4 are studied by in situ total-reflection fluorescence X-ray absorption spectroscopy (TRF-XAS), ex situ X-ray photoelectron spectroscopy (XPS), and electrochemical tests. Flat and well-defined thin films of LiNi0.5Mn1.5O4 prepared by pulsed laser deposition (PLD) are used as model electrodes to facilitate the observation of the interface. The thin-film LiNi0.5Mn1.5O4 electrode showed good cycling characteristics at around 4.7 V vs. Li/Li+. The TRF-XAS measurements reveal that nickel and manganese species at the surface have almost the same chemical states and local environments as those in the bulk when in contact with organic electrolyte solutions (1 mol dm-3 LiClO4 in a 1:1 volumetric mixture of ethylene carbonate and diethyl carbonate). This is in sharp contrast to the behavior of a LiCoO2 electrode, in which the surface cobalt species is irreversibly reduced by soaking to the organic electrolyte solutions, leading to gradual material deterioration during the delithiation/lithiation cycling (D. Takamatsu et al., Angew. Chem. Int. Edit., 51 (2012) 11597). It is suggested that the electrolyte decomposition products detected by XPS form a protective layer to restrict the reduction of the surface species of LiNi0.5Mn1.5O4, leading to good cycling characteristics of LiNi0.5Mn1.5O4 in spite of its high operating potential.

  17. Degradation effects on the surface of commercial LiNi0.5Co0.2Mn0.3O2 electrodes

    Science.gov (United States)

    Börner, M.; Horsthemke, F.; Kollmer, F.; Haseloff, S.; Friesen, A.; Niehoff, P.; Nowak, S.; Winter, M.; Schappacher, F. M.

    2016-12-01

    A comprehensive analysis of the degradation mechanisms on the surface of commercial LiNi0.5Co0.2Mn0.3O2 electrodes is presented. Irregularly distributed particle cracking and the formation of a cathode electrolyte interphase on the surface of the active material were identified to be the main degradation mechanisms. The particle cracking originates from inhomogeneity of the composite electrode, leading to deviations in the local current density and the state of charge which results in overcharge conditions for particular LiNi0.5Co0.2Mn0.3O2 particles. Therein, the highly delithiated structure suffers from anisotropic stress due to repulsive interactions between adjacent layers and the formation of new phases which eventually cause particle cracking. The structural changes were confirmed by the presence of a spinel phase on the surface of the cracked particles. Furthermore, the migration of transition metal ions in the highly delithiated structure can facilitate their dissolution into the electrolyte. The investigation of the re-deposited transition metals reveals a predominant dissolution of manganese from the overcharged particles. In addition, electrochemical cycling of the LiNi0.5Co0.2Mn0.3O2 electrodes in laboratory cells show an increasing severity of the particle cracking at higher C-rates which can influence the thermal stability of the active material. Moreover, an increased electrolyte decomposition was observed for higher cut-off potentials.

  18. Enhanced electrochemical performances of LiNi0.5Mn1.5O4 by surface modification with Cu nanoparticles

    Directory of Open Access Journals (Sweden)

    Zhao G.

    2017-01-01

    Full Text Available 5V spinel LiNi0.5Mn1.5O4 cathode is prepared by traditional solid-state method and nano-Cu particles were derived from a chemical reduction process. The effect of Cu-coating on the electrochemical performances of LiNi0.5Mn1.5O4 cells, in a wide operation temperature range (-10°C, 25°C, 60°C, is investigated systematically by the charge/discharge testing, cyclic voltammograms and impedance spectroscopy, respectively. The results demonstrate that the modified material exhibits remarkably enhanced electrochemical reversibility and stability. Cu-coated material has much lower surface and charge transfer resistances and shows a higher lithium diffusion rate. The Cu coating layer as a highly efficient lithium ion conductor, acted as a highly efficient protector to restrain the contact loss.

  19. Effect of Surface Modification on Nano-Structured LiNi(0.5)Mn(1.5)O4 Spinel Materials.

    Science.gov (United States)

    Cho, Hyung-Man; Chen, Michael Vincent; MacRae, Alex C; Meng, Ying Shirley

    2015-08-05

    Fine-tuning of particle size and morphology has been shown to result in differential material performance in the area of secondary lithium-ion batteries. For instance, reduction of particle size to the nanoregime typically leads to better transport of electrochemically active species by increasing the amount of reaction sites as a result of higher electrode surface area. The spinel-phase oxide LiNi0.5Mn1.5O4 (LNMO), was prepared using a sol-gel based template synthesis to yield nanowire morphology without any additional binders or electronic conducting agents. Therefore, proper experimentation of the nanosize effect can be achieved in this study. The spinel phase LMNO is a high energy electrode material currently being explored for use in lithium-ion batteries, with a specific capacity of 146 mAh/g and high-voltage plateau at ∼4.7 V (vs Li/Li(+)). However, research has shown that extensive electrolyte decomposition and the formation of a surface passivation layer results when LMNO is implemented as a cathode in electrochemical cells. As a result of the high surface area associated with nanosized particles, manganese ion dissolution results in capacity fading over prolonged cycling. In order to prevent these detrimental effects without compromising electrochemical performance, various coating methods have been explored. In this work, TiO2 and Al2O3 thin films were deposited using atomic layer deposition (ALD) on the surface of LNMO particles. This resulted in effective surface protection by prevention of electrolyte side reactions and a sharp reduction in resistance at the electrode/electrolyte interface region.

  20. Ocular surface evaluation in patients treated with a fixed combination of prostaglandin analogues with 0.5% timolol maleate topical monotherapy: a randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Heloisa Helena Russ

    Full Text Available OBJECTIVES: To compare ocular surface changes induced via glaucoma treatment in patients using fixed combinations of prostaglandin analogues (travoprost, latanoprost and bimatoprost with 0.5% timolol maleate METHODS: A prospective, multicenter, randomized, parallel group, single-blind clinical trial was performed in 33 patients with ocular hypertension or open angle glaucoma who had not been previously treated. The ocular surface was evaluated prior to and three months after treatment, with a daily drop instillation of one of the three medications. The main outcome measurements included the tear film break-up time, Schirmer's test, Lissamine green staining, the Ocular Surface Disease Index questionnaire, impression cytology using HE and PAS and immunocytochemistry for interleukin-6 and HLA-DR. Ensaiosclinicos.gov.br: UTN - U1111-1129-2872 RESULTS: All of the drugs induced a significant reduction in intraocular pressure. Decreases in the Schirmer's test results were observed with all of the drugs. Decreases in tear-film break-up time were noted with travoprost/timolol and latanoprost/timolol. An increase in the Lissamine green score was noted with travoprost/timolol and bimatoprost/timolol. The Ocular Surface Disease Index score increased after treatment in the travoprost/timolol group. Impression cytology revealed a significant difference in cell-to-cell contact in the same group, an increase in cellularity in all of the groups and an increase in the number of goblet cells in all of the groups. The fixed combinations induced an increase in IL-6 expression in the travoprost/timolol group, in which there was also an increase in HLA-DR expression. CONCLUSIONS: All of the fixed combinations induced a significant reduction in intraocular pressure, and the travoprost/timolol group showed increased expression of the inflammatory markers HLA-DR and interleukin-6. All three tested medications resulted in some degree of deterioration in the ocular surface

  1. Valuation of surfactant Phosphonates synthesized in the protection of metal surfaces against corrosion of mild steel in 0.5M H2SO4 media

    Directory of Open Access Journals (Sweden)

    R. Ghibate

    2015-12-01

    Full Text Available In this article, we are interesting to investigate the corrosion inhibition of mild steel in sulfuric acid by two surfactants phospohonates already synthesized namely sodium methyldodecylphosphonate (Pho1 and sodium methyl (11-methacryloyloxyundecyl phosphonate (Pho2. The inhibition performances of Pho1 and Pho2 on mild steel corrosion in 0,5M H2SO4 solution were studied using the electrochemical impedance spectroscopy (EIS, weight loss, and Tafel polarization technics. The experimental results suggest that those surfactants are effective corrosion inhibitors and the inhibition efficiency increases with the increase surfactants concentrations. Polarization measurements proved that the inhibitors behave as mixed-type. EIS diagram appears a large capacitive loop at high frequencies (HF followed by a small inductive loop at low frequencies (LF for Pho2, and the addition of this surfactant inhibitor increases the impedance of electrode. The adsorption of each surfactant on steel surface obeys Langmuir adsorption isotherm. The thermodynamic and kinetic parameters were calculated and discussed. Values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS are in good agreement.

  2. Modeling the Effects of Multi-layer Surface Roughness on 0.5 -2 GHz Passive Microwave Observations of the Greenland and Antarctic Ice Sheets

    Science.gov (United States)

    Tsang, L.; Wang, T.; Johnson, J.; Jezek, K. C.; Tan, S.

    2015-12-01

    The Ultra-Wideband Software-Defined Radiometer (UWBRAD) is being developed to provide measurements of ice sheet thermal emission over the frequency range 0.5-2 GHz. In this frequency range, density variations within the firn create a layered structure that cause reflections. The thicknesses of the layers are of the order of centimeters in the top 100 meters, so that there can be hundreds to thousands of layers. In the incoherent approach of modelling, the radiative transfer equation is applied to each layer. In the coherent approach, the fluctuation dissipation theorem with a layered medium Green's function is used to calculate the brightness temperature. However, layer roughness effects have not been accounted for. Rough surface scattering would cause coupling of the intensities in all directions and coupling between vertical and horizontal polarizations. We use a "partially coherent" approach. The snow firn is divided into "blocks" that include multiple layers separated by rough interfaces. The block size is defined such that a coherent incident wave will be attenuated to approximately 50% of its original amplitude upon transmission through the block. Within the block, we treat the wave scattering by rough surfaces coherently by using use the 2nd order small perturbation method (SPM2). The SPM2 is an efficient analytic method that obeys energy conservation. The block size can be as small as 10 meters for the top layers because of strong density fluctuations, but can be hundreds of meters deeper within the snow firn because of the smaller density variations at greater depths. We calculate the bistatic scattering and transmission coefficients for each block. Finally the scattering and emission from multiple blocks are combined incoherently by using a cascade approach of the input and output intensities of the block. Using the partially coherent approach, we can obtain the brightness temperatures of layered snow firn when there are hundreds or thousands of layers

  3. Fabrication and characterization of cubic Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3−δ} perovskite for a novel “star-shaped” oxygen membrane with a developed surface

    Energy Technology Data Exchange (ETDEWEB)

    Borhan, Adrian Iulian [Institute of Power Engineering, Ceramic Department CEREL, Research Institute, 1 Techniczna St., 36-040 Boguchwała (Poland); Gromada, Magdalena, E-mail: gromada@cerel.pl [Institute of Power Engineering, Ceramic Department CEREL, Research Institute, 1 Techniczna St., 36-040 Boguchwała (Poland); Samoila, Petrisor [Petru Poni Institute of Macromolecular Chemistry, 41A, Gr. Ghica Voda Alley, 700487 Iasi (Romania); Gherca, Daniel [Alexandru Ioan Cuza University of Iasi, Faculty of Chemistry, 11 Carol 1 Boulevard, R-700506 Iasi (Romania)

    2016-07-15

    Highlights: • Innovative fabrication technology was elaborated for BSCF membrane with developed surface. • The tool for membranes forming with developed surface was designed and executed. • As a result of forming process, membranes with “star shape” design were obtained. • Concentration of oxygen vacancies in BSCF increases considerably with temperature. • The small polaron hopping depends on the oxygen stoichiometry deviation. - Abstract: Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3−δ} (BSCF), a material which can be used for the fabrication of oxygen membranes with developed surfaces, was synthesized by a solid state method. The most important material properties which have influence on the oxygen membrane usability were investigated. An innovative fabrication technology was developed for the preparation of oxygen membranes with developed surfaces by using vacuum extrusion. The tool to form membranes on a vacuum worm press was designed and executed. These allowed the formation, for the first time, of a novel “star shaped” architecture for an oxygen membrane, enabling the use of a higher effective surface for oxygen production. Comprehensive studies on structural and microstructural properties, apparent density and porosity, water absorbability, oxygen stoichiometry, thermal expansion and electrical conductivity of the BSCF membrane were performed. The results obtained demonstrated the potential application of “star-shaped” oxygen membranes in oxy-fuel combustion technology.

  4. Effect of surface contamination on the hydriding behaviors of LaNi{sub 4.5}Al{sub 0.5}, LaNi{sub 2.5}Co{sub 2.5} and LaNi{sub 4.5}Mn{sub 0.5}

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, H. [Tokai Univ., Kanagawa (Japan). Dept. of Applied Physics; Seki, S. [Tokai Univ., Kanagawa (Japan). Dept. of Applied Physics; Seta, S. [Tokai Univ., Kanagawa (Japan). Dept. of Applied Physics

    1995-12-15

    The aim of this study was to elucidate the role of each substituent element such as Al, Co and Mn in the hydridings of LaNi{sub 4.5}Al{sub 0.5}, LaNi{sub 2.5}Co{sub 2.5} and LaNi{sub 4.5}Mn{sub 0.5} alloys exposed to contaminative conditions. The addition of Al was found effective to yield the H{sub 2}-dissociation-controlled kinetics even in extended surface contaminations. The effect of surface oxide containing Co seem to remain even in the hydriding reaction, indicating the formation of stable oxide layers for the Co-containing alloys in spite of the occurrence of a small volume expansion due to hydriding. The addition of Co yields the inhibitive pulverization, which indicates that the Co addition acts to form coherent interfaces between surface oxide layers and the alloy. The addition of Mn increases the sensitivity to contamination and markedly decreases the reaction rate in the formation of H solid solution where no pulverization takes place. However, because the pulverization is accelerated by the presence of various non-stoichiometric Mn oxides, the hydriding rate recovers to those of LaNi{sub 5} and LaNi{sub 4.5}Al{sub 0.5} with increasing number of cyclic hydriding-dehydriding reactions. The limited applicability of the Johnson-Mehl-Avrami-type equation to the measured hydriding curves is discussed from the measured kinetic results. (orig.)

  5. The microbiology of arable soil surfaces

    OpenAIRE

    Jeffery, Simon

    2007-01-01

    Whilst much is known about the physics and erosion of soil surfaces on a millimetre scale, little is known about the associated microbiology, particularly in temperate arable systems. The vast majority of research regarding microbial interactions at soil surfaces has concerned microbiotic crusts. However, such surface crusts take many years to form and then only in relatively undisturbed soil systems. Arable soil surfaces are subject to relatively extreme environmental conditio...

  6. Calibration and validation of the COSMOS rover for surface soil moisture

    Science.gov (United States)

    The mobile COsmic-ray Soil Moisture Observing System (COSMOS) rover may be useful for validating satellite-based estimates of near surface soil moisture, but the accuracy with which the rover can measure 0-5 cm soil moisture has not been previously determined. Our objectives were to calibrate and va...

  7. Surface stability of spinel MgNi{sub 0.5}Mn{sub 1.5}O{sub 4} and MgMn{sub 2}O{sub 4} as cathode materials for magnesium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Wei; Yin, Guangqiang [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Wang, Zhiguo, E-mail: zgwang@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Fu, Y.Q., E-mail: richard.fu@northumbria.ac.uk [Department of Physics and Electrical Engineering, Faculty of Engineering and Environment, University of Northumbria, Newcastle upon Tyne, NE1 8ST (United Kingdom)

    2016-11-01

    Highlights: • Surface of spinel MgMn{sub 2}O{sub 4} and MgNi{sub 0.5}Mn{sub 1.5}O{sub 4} cathodes were investigated. • The surface energies show less dependence on the Ni-doping. • Atomic reconstruction occurred due to atomic relaxation at the surface. - Abstract: Rechargeable ion batteries based on the intercalation of multivalent ions are attractive due to their high energy density and structural stability. Surface of cathode materials plays an important role for the electrochemical performance of the rechargeable ion batteries. In this work we calculated surface energies of (001), (110) and (111) facets with different terminations in spinel MgMn{sub 2}O{sub 4} and MgNi{sub 0.5}Mn{sub 1.5}O{sub 4} cathodes. Results showed clearly that atomic reconstruction occurred due to surface relaxation. The surface energies for the (001), (110) and (111) surfaces of the MgNi{sub 0.5}Mn{sub 1.5}O{sub 4} were 0.08, 0.13 and 0.11 J/m{sup 2}, respectively, whereas those of the Ni-doped MgMn{sub 2}O{sub 4} showed less dependence on the surface structures.

  8. Surface modeling of soil antibiotics.

    Science.gov (United States)

    Shi, Wen-jiao; Yue, Tian-xiang; Du, Zheng-ping; Wang, Zong; Li, Xue-wen

    2016-02-01

    Large numbers of livestock and poultry feces are continuously applied into soils in intensive vegetable cultivation areas, and then some veterinary antibiotics are persistent existed in soils and cause health risk. For the spatial heterogeneity of antibiotic residues, developing a suitable technique to interpolate soil antibiotic residues is still a challenge. In this study, we developed an effective interpolator, high accuracy surface modeling (HASM) combined vegetable types, to predict the spatial patterns of soil antibiotics, using 100 surface soil samples collected from an intensive vegetable cultivation area located in east of China, and the fluoroquinolones (FQs), including ciprofloxacin (CFX), enrofloxacin (EFX) and norfloxacin (NFX), were analyzed as the target antibiotics. The results show that vegetable type is an effective factor to be combined to improve the interpolator performance. HASM achieves less mean absolute errors (MAEs) and root mean square errors (RMSEs) for total FQs (NFX+CFX+EFX), NFX, CFX and EFX than kriging with external drift (KED), stratified kriging (StK), ordinary kriging (OK) and inverse distance weighting (IDW). The MAE of HASM for FQs is 55.1 μg/kg, and the MAEs of KED, StK, OK and IDW are 99.0 μg/kg, 102.8 μg/kg, 106.3 μg/kg and 108.7 μg/kg, respectively. Further, RMSE simulated by HASM for FQs (CFX, EFX and NFX) are 106.2 μg/kg (88.6 μg/kg, 20.4 μg/kg and 39.2 μg/kg), and less 30% (27%, 22% and 36%), 33% (27%, 27% and 43%), 38% (34%, 23% and 41%) and 42% (32%, 35% and 51%) than the ones by KED, StK, OK and IDW, respectively. HASM also provides better maps with more details and more consistent maximum and minimum values of soil antibiotics compared with the measured data. The better performance can be concluded that HASM takes the vegetable type information as global approximate information, and takes local sampling data as its optimum control constraints.

  9. NH 3 soil and soil surface gas measurements in a triticale wheat field

    Science.gov (United States)

    Neftel, A.; Blatter, A.; Gut, A.; Högger, D.; Meixner, F.; Ammann, C.; Nathaus, F. J.

    We present a new approach for a continuous determination of NH 3 concentration in the open pore space of the soil and on the soil surface. In a semi-permeable membrane of 0.5 m length a flow of 0.5 s1pm maintained. In the tube the NH 3 concentration adjusts itself to the surrounding air concentration by diffusion through the membrane. Continuous measurements have been performed in a triticale wheat field over a period of several weeks in a field experiment at Bellheim (FRG) during June and July 1995 within the frame of the European program EXAMINE (Exchange of Atmospheric Ammonia with European Ecosystems). Soil concentrations are generally below the detection limit of 0.1 μg m -3. We conclude, that the investigated soil is generally a sink for NH 3. The NH 3 concentration on the soil surface shows a diurnal variation due to a combination of physico-chemical desorption and adsorption phenomena associated with changes in wetness of the surrounding surfaces and the NH 3 concentration in the canopy.

  10. Morphological Evolution of High-Voltage Spinel LiNi(0.5)Mn(1.5)O4 Cathode Materials for Lithium-Ion Batteries: The Critical Effects of Surface Orientations and Particle Size.

    Science.gov (United States)

    Liu, Haidong; Wang, Jun; Zhang, Xiaofei; Zhou, Dong; Qi, Xin; Qiu, Bao; Fang, Jianhui; Kloepsch, Richard; Schumacher, Gerhard; Liu, Zhaoping; Li, Jie

    2016-02-01

    An evolution panorama of morphology and surface orientation of high-voltage spinel LiNi(0.5)Mn(1.5)O4 cathode materials synthesized by the combination of the microwave-assisted hydrothermal technique and a postcalcination process is presented. Nanoparticles, octahedral and truncated octahedral particles with different preferential growth of surface orientations are obtained. The structures of different materials are studied by X-ray diffraction (XRD), Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), and transmission electron microscopy (TEM). The influence of various morphologies (including surface orientations and particle size) on kinetic parameters, such as electronic conductivity and Li(+) diffusion coefficients, are investigated as well. Moreover, electrochemical measurements indicate that the morphological differences result in divergent rate capabilities and cycling performances. They reveal that appropriate surface-tailoring can satisfy simultaneously the compatibility of power capability and long cycle life. The morphology design for optimizing Li(+) transport and interfacial stability is very important for high-voltage spinel material. Overall, the crystal chemistry, kinetics and electrochemical performance of the present study on various morphologies of LiNi(0.5)Mn(1.5)O4 spinel materials have implications for understanding the complex impacts of electrode interface and electrolyte and rational design of rechargeable electrode materials for lithium-ion batteries. The outstanding performance of our truncated octahedral LiNi(0.5)Mn(1.5)O4 materials makes them promising as cathode materials to develop long-life, high energy and high power lithium-ion batteries.

  11. 熔融Sn-3.0Ag-0.5Cu在倾斜铜基板上表面形貌的模拟%Simulation analysis on the surface morphology of Sn-3.0Ag-0.5Cu melting on the inclined Cu substrate

    Institute of Scientific and Technical Information of China (English)

    徐秉声; 吴湖; 韩琳; 陈军伟; 袁章福

    2014-01-01

    通过润湿性实验,借助有限元软件Surface Evolver模拟研究了在490 K温度下熔融态的无铅焊料Sn-3.0Ag-0.5Cu在倾斜铜基板上的铺展行为及界面特性.根据经验方程拟合熔滴侧面轮廓曲线并获得三相点处的接触角大小.经计算发现,在基板的倾斜角度较小时,三相接触线几乎不发生移动,三相接触线的后三相点沿基板向前移动,前三相点保持不动,相应地,前进角逐渐增大并达到最大值.随着基板倾斜角度的继续增大,前三相点开始向前移动,导致前进角逐渐减小,最终熔滴从基板上滑落.通过模拟铺展过程表征了接触角的滞后现象;通过SEM及EDS手段分析界面微观结构,说明了在润湿过程中发生了界面化学反应,确定了金属间化合物Cu6Sn5生成并呈扇贝形分布.%To investigate interface properties of molten Sn-3.0Ag-0.5Cu solder melting on the inclined Cu substrate, numerical simulation is carried out by Surface Evolver at 490 K with wetting experiments. Profile curves of the droplets are fitted with empirical equation, which are proposed to obtain preferable contact angles. According to the experimental results, it is indicated that the contact line hardly moves at the very beginning and the rear point of triple line moves forward along the substrate subsequently, but the front point of triple line is still pinned on the substrate. Correspondingly ,the advancing contact angle gradually increases to the peak value. When the inclined angle of the substrate continues to increase, the advancing contact angle decreases along with the front point of triple line moving forward, and finally the drop slides down from the substrate. In this paper, contact angle hysteresis is characterized by the numerical simulation. Furthermore, the interface microstructure is observed by means of SEM and EDS. It is illustrated that the interfacial chemical reaction happens in the wetting process which

  12. Inhibition of Viability, Proliferation, Cytokines Secretion, Surface Antigen Expression, and Adipogenic and Osteogenic Differentiation of Adipose-Derived Stem Cells by Seven-Day Exposure to 0.5 T Static Magnetic Fields

    Directory of Open Access Journals (Sweden)

    Jian Wang

    2016-01-01

    Full Text Available After seven-day exposure to 0.5-Tesla Static Magnetic Field (SMF, Adipose-derived Stem Cells (ASCs and those labeled by superparamagnetic iron oxide (SPIO nanoparticles were examined for viability by methyl thiazol tetrazolium (MTT assay, proliferation by cell counting and bromodeoxyuridine (BrdU incorporation, DNA integrity by single cell gel electrophoresis, surface antigen by flow cytometry analysis, and the expression of cytokines and genetic markers by reverse transcription-PCR and underwent adipogenic and osteogenic differentiation assessed by quantifying related specific genes expression. The SMF slightly reduced cell viability and proliferation and inhibited the expression of CD49d, CD54, and CD73 but did not damage DNA integrity. The SMF slightly downregulated the expression of cytokines including Vascular Endothelial Growth Factor (VEGF, Insulin-like Growth Factor-1 (IGF-1, Transforming Growth Factor Beta 1 (TGF-β1, genetic markers comprising Stem Cell Antigen-1 (Sca1, Octamer-4 (Oct-4, ATP-binding Cassette Subfamily B Member 1 (ABCB1, adipogenic marker genes containing Lipoprotein Lipase (LPL, Peroxisome Proliferator-Activated Receptor Gamma (PPAR-γ, and osteogenic marker genes including Secreted Phosphor-protein 1 (SPP1 and Osterix (OSX. Exposure to 0.5 T SMF for seven days inhibited viability, proliferation, surface antigen expression, cytokine secretion, stem cell genetic marker expression, and adipogenic and osteogenic differentiation but did not affect the DNA integrity in ASCs with or without SPIO labeling.

  13. HONO fluxes from soil surfaces: an overview

    Science.gov (United States)

    Wu, Dianming; Sörgel, Matthias; Tamm, Alexandra; Ruckteschler, Nina; Rodriguez-Caballero, Emilio; Cheng, Yafang; Pöschl, Ulrich; Weber, Bettina

    2016-04-01

    Gaseous nitrous acid (HONO) contributes up to 80% of atmospheric hydroxyl (OH) radicals and is also linked to health risks through reactions with tobacco smoke forming carcinogens. Field and modeling results suggested a large unknown HONO source in the troposphere during daytime. By measuring near ground HONO mixing ratio, up to 30% of HONO can be released from forest, rural and urban ground as well as snow surfaces. This source has been proposed to heterogeneous reactions of nitrogen dioxide (NO2) on humic acid surfaces or nitric acid photolysis. Laboratory studies showed that HONO emissions from bulk soil samples can reach 258 ng m-2 s-1 (in term of nitrogen), which corresponding to 1.1 × 1012 molecules cm-2 s-1and ˜ 100 times higher than most of the field studies, as measured by a dynamic chamber system. The potential mechanisms for soil HONO emissions include chemical equilibrium of acid-base reaction and gas-liquid partitioning between soil nitrite and HONO, but the positive correlation of HONO fluxes with pH (largest at neutral and slightly alkaline) points to the dominance of the formation process by ammonia-oxidizing bacteria (AOB). In general soil surface acidity, nitrite concentration and abundance of ammonia-oxidizing bacteria mainly regulate the HONO release from soil. A recent study showed that biological soil crusts in drylands can also emit large quantities of HONO and NO, corresponding to ˜20% of global nitrogen oxide emissions from soils under natural vegetation. Due to large concentrations of microorganisms in biological soil crusts, particularly high HONO and NO emissions were measured after wetting events. Considering large areas of arid and arable lands as well as peatlands, up to 70% of global soils are able to emitting HONO. However, the discrepancy between large soil HONO emissions measured in lab and low contributions of HONO flux from ground surfaces in field as well as the role of microorganisms should be further investigated.

  14. BIOREMEDIATION OF CONTAMINATED SURFACE SOILS

    Science.gov (United States)

    Biological remediation of soils contaminated with organic chemicals is an alternative treatment technology that can often meet the goal of achieving a permanent clean-up remedy at hazardous waste sites, as encouraged by the U.S. Environmental Protection Agency (U.S. EPA) for impl...

  15. Significant improvement in performances of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} through surface modification with high ordered Al-doped ZnO electro-conductive layer

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hongdan; Xia, Bingbo [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Liu, Weiwei [Changzhou Institute of Energy Storage Materials & Devices, Changzhou 213000 (China); Fang, Guoqing; Wu, Jingjing; Wang, Haibo; Zhang, Ruixue [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Kaneko, Shingo [Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Zheng, Junwei [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Wang, Hongyu [Changzhou Institute of Energy Storage Materials & Devices, Changzhou 213000 (China); Li, Decheng, E-mail: lidecheng@suda.edu.cn [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Laboratory of Lithium Ion Battery Materials of Jiangsu Province, Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China)

    2015-03-15

    Graphical abstract: Al-doped ZnO (AZO)-coated LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} (LNMO) was prepared by sol–gel method. AZO-coated LNMO electrode shows excellent rate capability and a remarkable improvement in the cyclic performance at a high rate at elevated temperature. - Highlights: • Al-doped ZnO (AZO)-coated LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} (LNMO) was prepared by a traditional sol–gel method. • Al-doped ZnO (AZO) layer grown on the surface of LNMO is high ordered. • At a high rate of 10 C, the discharge capacity of the AZO-coated LNMO electrode can reach 114 mAh g{sup −1}. • Al-doped ZnO (AZO) modification improved cyclic performance of LNMO at high temperatures. - Abstract: Al-doped ZnO (AZO)-coated LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} (LNMO) was prepared by sol–gel method. Transmission electron microscopy (TEM) analysis indicates that AZO layer grown on the surface of LNMO is high ordered. The results of electrochemical performance measurements reveal that the AZO-coated LNMO electrode displays the best rate capability compared with the bare LNMO and ZnO-coated LNMO, even at a high rate of 10 C. The discharge capacity of the AZO-coated LNMO electrode can still reach 114.3 mAh g{sup −1}, about 89% of its discharge capacity at 0.1 C. Moreover, AZO-coated LNMO electrode shows a remarkable improvement in the cyclic performance at a high rate at elevated temperature due to the protective effect of AZO coating layer. The electrode delivers a capacity of 120.3 mAh g{sup −1} with the capacity retention of 95% at 5 C in 50 cycles at 50 °C. The analysis of electrochemical impedance spectra (EIS) indicates that AZO-coated LNMO possesses the lowest charge transfer resistance compared to the bare LNMO and ZnO-coated LNMO, which may be responsible for improved rate capability.

  16. VTORTHO_0_5M_PAN

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN data is a composite dataset that includes the latest pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter...

  17. Composite coating of Li2O-2B2O3 and carbon as multi-conductive electron/Li-ion channel on the surface of LiNi0.5Mn1.5O4 cathode

    Science.gov (United States)

    Lee, Kanghyeon; Yang, Gene Jaehyoung; Kim, Hackyeon; Kim, Taejoong; Lee, Sun Sook; Choi, Si-Young; Choi, Sungho; Kim, Yongseon

    2017-10-01

    The coating effects of electronically and ionically conductive materials on the surface of LiNi0.5Mn1.5O4 (LNMO) cathodes for Li-ion batteries are examined. In order for the coating layers to promote facile electrochemical reactions, in addition to their protective functions of blocking side reactions between the LNMO surface and the electrolyte, carbon and Li2O-2B2O3 (LBO), which conduct electrons and Li ions, respectively, are chosen as coating materials. The properties of the LBO-carbon composite coating are examined in comparison with those of carbon- or LBO-only coatings. Electrochemical metrics, such as discharge capacity, rate performance, and cyclability, are improved with the addition of the thin-film coatings. The LBO-carbon coating shows the best overall properties, particularly greatly improved capacity retention under elevated-temperature (60 °C) cycling. The multi-conductive feature of LBO-carbon for both electrons and Li ions provides stable electrochemical kinetics under conditions of severe side reactions at elevated temperatures. The proposed simple one-step aqueous process for forming and applying the composite electrode coating may be extended to other materials and the mass production thereof.

  18. The Dependence of Star Formation Activity on Stellar Mass Surface Density and Sersic Index in zCOSMOS Galaxies at 0.5

    CERN Document Server

    Maier, C; Zamorani, G; Scodeggio, M; Lamareille, F; Contini, T; Sargent, M T; Scarlata, C; Oesch, P; Carollo, C M; Le Fèvre, O; Renzini, A; Kneib, J -P; Mainieri, V; Bardelli, S; Bolzonella, M; Bongiorno, A; Caputi, K; Coppa, G; Cucciati, O; De la Torre, S; de Ravel, L; Franzetti, P; Garilli, B; Iovino, A; Kampczyk, P; Knobel, C; Kovac, K; Le Borgne, J F; Le Brun, V; Mignoli, M; Pellò, R; Peng, Y; Montero, E Perez; Ricciardelli, E; Silverman, J D; Tanaka, M; Tasca, L; Tresse, L; Vergani, D; Zucca, E; Abbas, U; Bottini, D; Cappi, A; Cassata, P; Cimatti, A; Fumana, M; Guzzo, L; Halliday, C; Leauthaud, A; MacCagni, D; Marinoni, C; McCracken, H J; Memeo, P; Meneux, B; Porciani, C; Pozzetti, L; Scaramella, R; Walcher, J

    2009-01-01

    In order to try to understand the internal evolution of galaxies and relate this to the global evolution of the galaxy population, we present a comparative study of the dependence of star formation rates on the average surface mass densities (SigmaM) of galaxies at 0.5 < z < 0.9 and 0.04surface mass density log(SigmaMchar) ~ 8.5 at which the SSFR is seen to drop. Turning to zCOSMOS, we find a similar shape for the median SSFR - SigmaM relation, but with median SSFR values that are...

  19. Quantitative Characterization of the Surface Evolution for LiNi0.5Co0.2Mn0.3O2/Graphite Cell during Long-Term Cycling.

    Science.gov (United States)

    Zheng, Huiyuan; Qu, Qunting; Zhu, Guobin; Liu, Gao; Battaglia, Vincent S; Zheng, Honghe

    2017-03-29

    Many factors have been brought forward to explain the capacity degradation mechanisms of LiNixCoyMnzO2 (NCM)/graphite cells at extreme conditions such as under high temperature or with high cutoff voltage. However, the main factors dominating the long-term cycling performance under normal operations remain elusive. Quantitative analyses of the electrode surface evolution for a commercial 18650 LiNi0.5Co0.2Mn0.3O2 (NCM523)/graphite cell during ca. 3000 cycles under normal operation are presented. Electrochemical analyses and inductively coupled plasma-optical emission spectroscopy (ICP-OES) confirm lithium inventory loss makes up for ca. 60% of the cell's capacity loss. Electrochemical deterioration of the NCM523 cathode is identified to be another important factor, which accounts for more than 30% of the capacity decay. Irregular primary particle cracking due to the mechanical stress and the phase change aroused from Li-Ni mixing during repetitive cycles are identified to be the main contributors for the NCM cathode deterioration. The amount of transition metal dissolved into electrolyte is determined to be quite low, and the resulting impedance rise after about 3000 cycles is obtained to be twice that of the reference cell, which are not very significant affecting the long-term cycling performance under normal operations.

  20. Significant improvement in performances of LiNi0.5Mn1.5O4 through surface modification with high ordered Al-doped ZnO electro-conductive layer

    Science.gov (United States)

    Sun, Hongdan; Xia, Bingbo; Liu, Weiwei; Fang, Guoqing; Wu, Jingjing; Wang, Haibo; Zhang, Ruixue; Kaneko, Shingo; Zheng, Junwei; Wang, Hongyu; Li, Decheng

    2015-03-01

    Al-doped ZnO (AZO)-coated LiNi0.5Mn1.5O4 (LNMO) was prepared by sol-gel method. Transmission electron microscopy (TEM) analysis indicates that AZO layer grown on the surface of LNMO is high ordered. The results of electrochemical performance measurements reveal that the AZO-coated LNMO electrode displays the best rate capability compared with the bare LNMO and ZnO-coated LNMO, even at a high rate of 10 C. The discharge capacity of the AZO-coated LNMO electrode can still reach 114.3 mAh g-1, about 89% of its discharge capacity at 0.1 C. Moreover, AZO-coated LNMO electrode shows a remarkable improvement in the cyclic performance at a high rate at elevated temperature due to the protective effect of AZO coating layer. The electrode delivers a capacity of 120.3 mAh g-1 with the capacity retention of 95% at 5 C in 50 cycles at 50 °C. The analysis of electrochemical impedance spectra (EIS) indicates that AZO-coated LNMO possesses the lowest charge transfer resistance compared to the bare LNMO and ZnO-coated LNMO, which may be responsible for improved rate capability.

  1. Surface runoff, subsurface drainflow and soil erosion as affected by tillage in a clayey Finnish soil

    National Research Council Canada - National Science Library

    Turtola, Eila; Alakukku, Laura; Uusitalo, Risto; Kaseva, Antti

    2007-01-01

    Conservation tillage practices were tested against autumn mouldboard ploughing for differences in physical properties of soil, surface runoff, subsurface drainflow and soil erosion. The study (1991-2001...

  2. Soil moisture sensor calibration for organic soil surface layers

    Directory of Open Access Journals (Sweden)

    S. Bircher

    2015-12-01

    Full Text Available This paper's objective is to present generic calibration functions for organic surface layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology HOBE. For the Decagon 5TE sensor such a function is currently not reported in literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral layers with low soil organic matter (SOM content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified: for the Decagon 5TE apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger non-linearity in the sensor response and signal saturation in the high level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic surface layer at the Sodankylä site was significantly improved when the here proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic surface layers at the Sodankyl

  3. Soil moisture sensor calibration for organic soil surface layers

    Science.gov (United States)

    Bircher, Simone; Andreasen, Mie; Vuollet, Johanna; Vehviläinen, Juho; Rautiainen, Kimmo; Jonard, François; Weihermüller, Lutz; Zakharova, Elena; Wigneron, Jean-Pierre; Kerr, Yann H.

    2016-04-01

    This paper's objective is to present generic calibration functions for organic surface layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finnish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology (HOBE). For the Decagon 5TE sensor such a function is currently not reported in the literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified. For the Decagon 5TE, apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large specific surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger nonlinearity in the sensor response and signal saturation in the high-level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic surface layer at the Sodankylä site was significantly improved when the here-proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic surface layers at the Sodankylä and

  4. Oxygen evolution on Lasub(0. 5)Basub(0. 5)CoO/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Willems, H.; Kobussen, A.G.C.; Wit, J.H.W. de

    1985-10-25

    The recovery behaviour of an aged Lasub(0.5)Basub(0.5)CoO/sub 3/ electrode after interrupting a cathodic discharge current (forced decay, all starting from a high prepolarized state) at a still positive overpotential of 150 mV is discussed. It was found that the potential rises again after interrupting the cathodic current. This rise in potential decreases with decreasing cathodic currents when the electrodes are stabilized at the same starting overpotential before applying the cathodic current. The rise in potential also decreases with decreasing starting overpotential for the same cathodic discharge current. From these measurements it was concluded that higher oxides are present to a certain depth in the oxide layer at high positive overpotentials. Open-circuit decay measurements with different starting overpotentials were performed, all showing logarithmic slopes of proportional50 mV/dec. The decay rates increased for lower starting overpotentials. Impedances were measured during a decay, from which effective capacitances were calculated. For a given overpotential, the capacitances during a decay were practically constant in the overpotential range from 220 to 150 mV for a given starting overpotential. But for higher starting overpotentials the capacitances were found to be higher. These effects are explained by a change in effective surface area for different starting overpotentials caused by the above-mentioned higher oxides blocking the surface. (orig.).

  5. Plutonium, (137)Cs and uranium isotopes in Mongolian surface soils.

    Science.gov (United States)

    Hirose, K; Kikawada, Y; Igarashi, Y; Fujiwara, H; Jugder, D; Matsumoto, Y; Oi, T; Nomura, M

    2017-01-01

    Plutonium ((238)Pu and (239,240)Pu), (137)Cs and plutonium activity ratios ((238)Pu/(239,240)Pu) as did uranium isotope ratio ((235)U/(238)U) were measured in surface soil samples collected in southeast Mongolia. The (239,240)Pu and (137)Cs concentrations in Mongolian surface soils (surface soils (0.013-0.06) coincided with that of global fallout. The (235)U/(238)U atom ratios in the surface soil show the natural one. There was a good correlation between the (239,240)Pu and (137)Cs concentrations in the surface soils. We introduce the migration depth to have better understanding of migration behaviors of anthropogenic radionuclides in surface soil. We found a difference of the migration behavior between (239,240)Pu and (137)Cs from (137)Cs/(239,240)Pu - (137)Cs plots for the Mongolian and Tsukuba surface soils; plutonium in surface soil is migrated easier than (137)Cs.

  6. Surface soil factors and soil characteristics in geo-physical milieu of Kebbi State Nigeria

    Directory of Open Access Journals (Sweden)

    Suleiman Usman

    2016-07-01

    Full Text Available Soil erodibility (K factor is the most important tool for estimation the erosion. The aim of this study Soil factors and surface soil characteristics are important components of agricultural environment. They support surface and subsurface soils to perform many functions to agriculture and economic human developments. Understanding these factors would aid to the recognition of the values that our soil and land offered to humanity. It is therefore, aim of this study to visualise and examine the soil factors and surface soil characteristics in Kebbi State Nigeria. An Integrated Surface Soil Approach (ISSA was used in the classification and description of soil environment in the study region. The factors constituted in the ISSA are important components of soil science that theories and practice(s noted to provide ideas on how soil environment functioned. The results indicate that the surface soil environments around Arewa, Argungu, Augie, Birnin Kebbi and Dandi are physically familiar with the following surface soil characteristics: bad-lands, blown-out-lands, cirque-lands, fertile-lands, gullied-lands, miscellaneous and rock-outcrops.The major soil factors observed hat played an important role in surface soil manipulations and soil formation are alluvial, colluvial, fluvial and lacustrine; ant, earthworms and termite; and various forms of surface relief supported by temperature, rainfall, relative humidity and wind. Overall, the surface soil environment of the region was describe according to their physical appearance into fadama clay soils, fadama clay-loam soils, dryland sandy soils, dryland sandy-loam soils, dryland stony soils and organic-mineral soils.

  7. A Comprehensive Laboratory Study to Improve Ground Truth Calibration of Remotely Sensed Near-Surface Soil Moisture

    Science.gov (United States)

    Babaeian, E.; Tuller, M.; Sadeghi, M.; Sheng, W.; Jones, S. B.

    2016-12-01

    Optical satellite and airborne remote sensing (RS) have been widely applied for characterization of large-scale surface soil moisture distributions. However, despite the excellent spatial resolution of RS data, the electromagnetic radiation within the optical bands (400-2500 nm) penetrates the soil profile only to a depth of a few millimeters; hence obtained moisture estimates are limited to the soil surface region. Furthermore, moisture sensor networks employed for ground truth calibration of RS observations commonly exhibit very limited spatial resolution, which consequently leads to significant discrepancies between RS and ground truth observations. To better understand the relationship between surface and near-surface soil moisture, we employed a benchtop hyperspectral line-scan imaging system to generate high resolution surface reflectance maps during evaporation from soil columns filled with source soils covering a wide textural range and instrumented with a novel time domain reflectometry (TDR) sensor array that allows monitoring of near surface moisture at 0.5-cm resolution. A recently developed physical model for surface soil moisture predictions from shortwave infrared reflectance was applied to estimate surface soil moisture from surface reflectance and to explore the relationship between surface and near-surface moisture distributions during soil drying. Preliminary results are very promising and their applicability for ground truth calibration of RS observations will be discussed.

  8. First-Principles Study of Doped Half-Metallic Spinels: Cu0.5Zn0.5Cr2S4,Cu0.5Cd0.5Cr2S4, Li0.5Zn0.5Cr2O4 and Li0.5Zn0.5Cr2S4

    Institute of Scientific and Technical Information of China (English)

    ZHOU Tie-Ge; LIU Zhi-Qiang; ZUO Xu

    2012-01-01

    Electronic structure and magnetic properties of Cu0.5 Zn0.5 Cr2S4, Cu0.5 Cd0.5 CrS4, Li0.5 Zn0.5 CrO4 and Li0.5 Zn0.5 Cr2S4 are investigated using the first-principles calculation based on the density functional theory. GGA+U exchange correlation is used in the calculation to correct the effective Coulomb repulsion energy of Cr underestimated by LSDA or GGA. The calculation results reveal that half-metallic Cu0.5 Zn0.5 Cr2S4 and Cu0.5 Cd0.5 CrS4 can be achieved by doping CuCr2S4 with Zn or Cd, though CuCr2S4 is not half-metallic. Half-metallic LiCr2O4 is experimentally unstable, but half-metallic Li0.5 Zn0.5 Cr2O4 and Li0.5 Zn0.5 Cr2S4 can be achieved by doping Li into experimentally stable ZnCr2O4 and ZnCr2S4, though ZnCr2O4 and ZnCr2S4 are not half-metallic. The influence of +U on the electronic structure and half-metallicity of the doped systems is also presented.%Electronic structure and magnetic properties of Cu0.5 Zn0.5 Cr2S4,Cu0.5 5 Cd0.5 Cr2S4,Li0.5 Zn0.5 Cr2O4 and Li0.5 Zn0.5 Cr2S4 are investigated using the first-principles calculation based on the density functional theory.GGA +U exchange correlation is used in the calculation to correct the effective Coulomb repulsion energy of Cr underestimated by LSDA or GGA.The calculation results reveal that half-metallic Cu0.5Zn0.5Cr2S4 and Cu0.5Cd0.5Cr2S4 can be achieved by doping CuCr2S4 with Zn or Cd,though CuCr2S4 is not half-metallic.Half-metallic LiCr2O4 is experimentally unstable,but half-metallic Li0.5Zn0.5 Cr2O4 and Li0.5Zn0.5 Cr2S4 can be achieved by doping Li into experimentally stable ZnCr2O4 and ZnCr2S4,though ZnCr2O4 and ZnCr2S4 are not half-metallic.The influence of +U on the electronic structure and half-metallicity of the doped systems is also presented.

  9. Remote Sensing and Synchronous Land Surface Measurements of Soil Moisture and Soil Temperature in the Field

    Science.gov (United States)

    Kolev, N. V.; Penev, K. P.; Kirkova, Y. M.; Krustanov, B. S.; Nazarsky, T. G.; Dimitrov, G. K.; Levchev, C. P.; Prodanov, H. I.; Kraleva, L. H.

    1998-01-01

    The paper presents the results of remote sensing and synchronous land surface measurements for estimation of soil (surface and profile) water content and soil temperature for different soil types in Bulgaria. The relationship between radiometric temperature and soil surface water content is shown. The research is illustrated by some results from aircraft and land surface measurements carried out over three test areas near Pleven, Sofia and Plovdiv, respectively, during the period 1988-1990.

  10. Structural, dielectric and impedance characteristics of (Sm0.5Li0.5)(Fe0.5V0.5)O3 multiferroics

    Science.gov (United States)

    Nath, Susmita; Barik, Subrat Kumar; Choudhary, R. N. P.; Barik, Sujit Kumar

    2017-07-01

    A single phase multiferroic magnetoelectric compound, (Sm0.5Li0.5)(Fe0.5V0.5)O3, is found at room temperature. This sample is fabricated using solid state reaction route. Analysis of the structural properties of the sample by X-ray diffraction method confirmed the fabrication of the desired compound with orthorhombic unit cell structure. Morphological property of the sample is recorded by field emission scanning electron microscopy (FE-SEM). Impedance spectroscopy is employed to determine the various electrical parameters such as dielectric constant, loss tangent, impedance, electric modulus, etc. at different temperature (RT-400 °C) within a frequency range of (1 kHz-1 MHz). Furthermore, the bulk resistance as function of temperature and J-E characteristic showed the semiconducting behavior of sample with negative temperature coefficient of resistance (NTCR) type nature of the compound. The M-H loop of this sample indicates the ferromagnetic nature with very low coercive field. A dedicated magnetoelectric set up is used to measure the ME coefficient as a function of magnetic field and found a significant ME coefficient of 2.99 mV Cm-1 Oe-1 at room temperature.

  11. Concentrations and geographic distribution of selected organic pollutants in Scottish surface soils.

    Science.gov (United States)

    Rhind, S M; Kyle, C E; Kerr, C; Osprey, M; Zhang, Z L; Duff, E I; Lilly, A; Nolan, A; Hudson, G; Towers, W; Bell, J; Coull, M; McKenzie, C

    2013-11-01

    Concentrations of selected persistent organic pollutants (POPs) representing three chemical classes (polycyclic aromatic hydrocarbons (PAH), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) and the organic pollutant diethylhexyl phthalate (DEHP), were determined in surface soil samples (0-5 cm) collected at 20 km grid intersects throughout Scotland over a three-year period. Detectable amounts of all chemical classes and most individual congeners were present in all samples. There were no consistent effects of soil or vegetation type, soil carbon content, pH, altitude or distance from centres of population on concentrations which exhibited extreme variation, even in adjacent samples. It is concluded that soil POPs and DEHP concentrations and associated rates of animal and human exposure were highly variable, influenced by multiple, interacting factors, and not clearly related to local sources but possibly related to wet atmospheric deposition and the organic carbon content of the soil. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Relationship between Mineral Soil Surface Area and the Biological Degradation of Biosolids Added to Soil

    Directory of Open Access Journals (Sweden)

    Dongqi Wen

    2015-12-01

    Full Text Available Geochemical and biological processes that operate in the soil matrix and on the soil surface are important to the degradation of biosolids in soil. Due to the large surface area of soils it is assumed that the microbial ecology is associated with mineral soil surface area. The total mineral surface areas were determined for soils from eight different fields selected from a long term study (1972–2006 of annual biosolids application to 41 fields in central Illinois varying in size from 3.6 to 66 ha. The surface areas for the soils varied from 1 to 9 m2/g of soil. The biological degradation rates for the eight soils were determined using a biological degradation rate model (DRM and varied from 0.02 to 0.20/year−1. Regression analysis revealed that the degradation rate was positively associated with mineral soil surface area (1 m2/g produces 0.018 year−1 increase in the degradation rate. The annual soil sequestration rate was calculated to increase from 1% to 6% when the soil total surface area increased from 1 to 9 m2/g of soil. Therefore, land application of biosolids is an effective way to enhance carbon sequestration in soils and reduce greenhouse gas emissions.

  13. Ultrathin Hf0.5Zr0.5O2 Ferroelectric Films on Si.

    Science.gov (United States)

    Chernikova, Anna; Kozodaev, Maksim; Markeev, Andrei; Negrov, Dmitrii; Spiridonov, Maksim; Zarubin, Sergei; Bak, Ohheum; Buragohain, Pratyush; Lu, Haidong; Suvorova, Elena; Gruverman, Alexei; Zenkevich, Andrei

    2016-03-23

    Because of their immense scalability and manufacturability potential, the HfO2-based ferroelectric films attract significant attention as strong candidates for application in ferroelectric memories and related electronic devices. Here, we report the ferroelectric behavior of ultrathin Hf0.5Zr0.5O2 films, with the thickness of just 2.5 nm, which makes them suitable for use in ferroelectric tunnel junctions, thereby further expanding the area of their practical application. Transmission electron microscopy and electron diffraction analysis of the films grown on highly doped Si substrates confirms formation of the fully crystalline non-centrosymmetric orthorhombic phase responsible for ferroelectricity in Hf0.5Zr0.5O2. Piezoresponse force microscopy and pulsed switching testing performed on the deposited top TiN electrodes provide further evidence of the ferroelectric behavior of the Hf0.5Zr0.5O2 films. The electronic band lineup at the top TiN/Hf0.5Zr0.5O2 interface and band bending at the adjacent n(+)-Si bottom layer attributed to the polarization charges in Hf0.5Zr0.5O2 have been determined using in situ X-ray photoelectron spectroscopy analysis. The obtained results represent a significant step toward the experimental implementation of Si-based ferroelectric tunnel junctions.

  14. Inverse modeling of soil characteristics from surface soil moisture observations: potential and limitations

    Directory of Open Access Journals (Sweden)

    A. Loew

    2008-01-01

    Full Text Available Land surface models (LSM are widely used as scientific and operational tools to simulate mass and energy fluxes within the soil vegetation atmosphere continuum for numerous applications in meteorology, hydrology or for geobiochemistry studies. A reliable parameterization of these models is important to improve the simulation skills. Soil moisture is a key variable, linking the water and energy fluxes at the land surface. An appropriate parameterisation of soil hydraulic properties is crucial to obtain reliable simulation of soil water content from a LSM scheme. Parameter inversion techniques have been developed for that purpose to infer model parameters from soil moisture measurements at the local scale. On the other hand, remote sensing methods provide a unique opportunity to estimate surface soil moisture content at different spatial scales and with different temporal frequencies and accuracies. The present paper investigates the potential to use surface soil moisture information to infer soil hydraulic characteristics using uncertain observations. Different approaches to retrieve soil characteristics from surface soil moisture observations is evaluated and the impact on the accuracy of the model predictions is quantified. The results indicate that there is in general potential to improve land surface model parameterisations by assimilating surface soil moisture observations. However, a high accuracy in surface soil moisture estimates is required to obtain reliable estimates of soil characteristics.

  15. Gamma-ray computed tomography to characterize soil surface sealing

    Energy Technology Data Exchange (ETDEWEB)

    Pires, L.F.Luiz F. E-mail: lfpires@cena.usp.br; Macedo, Jose R. de; Souza, Manoel D. de; Bacchi, Osny O.S.; Reichardt, Klaus

    2002-09-01

    The application of sewage sludge as a fertilizer on soils may cause compacted surface layers (surface sealing), which can promote changes on soil physical properties. The objective of this work was to study the use of gamma-ray computed tomography, as a diagnostic tool for the evaluation of this sealing process through the measurement of soil bulk density distribution of the soil surface layer of samples subjected to sewage sludge application. Tomographic images were taken with a first generation tomograph with a resolution of 1 mm. The image analysis opened the possibility to obtain soil bulk density profiles and average soil bulk densities of the surface layer and to detect the presence of soil surface sealing. The sealing crust thickness was estimated to be in the range of 2-4 mm.

  16. Emission of Rare Earth Complex Tb0.5Eu0.5(asprin)3phen

    Institute of Scientific and Technical Information of China (English)

    沈鸿; 徐征; 陶栋梁; 徐怡庄; 章婷; 杨军

    2003-01-01

    The coprecipitate Tb0.5Eu0.5(asprin)3phen was synthesized. By doping the rare earth complex into polymer PVK, the EL device was fabricated with the structure of ITO/PVK∶RE/PBD/Al. Compared with the device using PVK/Eu(asprin)3phen blend as the light emitting layer, the emission of Eu3+ in the PVK/Tb0.5Eu0.5(asprin)3 phen blend is greatly enhanced along with the quenching of the emission of PVK.

  17. Divergent surface and total soil moisture projections under global warming

    Science.gov (United States)

    Berg, Alexis; Sheffield, Justin; Milly, Paul C.D.

    2017-01-01

    Land aridity has been projected to increase with global warming. Such projections are mostly based on off-line aridity and drought metrics applied to climate model outputs but also are supported by climate-model projections of decreased surface soil moisture. Here we comprehensively analyze soil moisture projections from the Coupled Model Intercomparison Project phase 5, including surface, total, and layer-by-layer soil moisture. We identify a robust vertical gradient of projected mean soil moisture changes, with more negative changes near the surface. Some regions of the northern middle to high latitudes exhibit negative annual surface changes but positive total changes. We interpret this behavior in the context of seasonal changes in the surface water budget. This vertical pattern implies that the extensive drying predicted by off-line drought metrics, while consistent with the projected decline in surface soil moisture, will tend to overestimate (negatively) changes in total soil water availability.

  18. Reconstruction of ploughed soil surface with 3D fractal interpolation

    NARCIS (Netherlands)

    Liu, Y.; Lu, Z.; Hoogmoed, W.B.; Li, X.

    2014-01-01

    By using a laser profiler, the roughness of ploughed soil surface was obtained. 3D fractal interpolation method was used to interpolate several kinds of reduced measured surface data which were reduced from the original measured ploughed soil surface elevation data in different reduction rates. Also

  19. Surface Chemical Properties of Colloids in Main Soils of China

    Institute of Scientific and Technical Information of China (English)

    MAYI-JIE; YUANCHAO-LIANG

    1991-01-01

    Surface chemical properties of soil colloids are the important factor affecting soil fertility and genesis.To provide scientific basis for soil genetic classification,promotion of soil fertility and reasonable fertilizqation,the specific surface area and electric charge of soil colloids in relation to clay minerals and organic matter are further discussed on the basis of the results obtained from the studies on surface chemical properties of soil colloids in five main soils of China.Results from the studies show that the effect of clay minerals and organic matter on the surface chemical properties of soil colloids is very complicated because the siloxane surface,hydrated oxide surface and organic matter surface do not exist separately,but they are always mixed together and influenced each other.The understanding of the relationship among clay minerals,organic matter and surface chemical properties of soil colloids depends upon further study of the relevant disciplines of soil science,especially the study on the mechanisms of organo-mineral complexes.

  20. Elastic Properties of Ho0.5Er0.5 Single Crystal

    DEFF Research Database (Denmark)

    Spichkin, Yu.I.; Bohr, Jakob; Tishin, A.M.

    1996-01-01

    The results of an investigation of the Young's modulus E and the interval friction Q-1 of a Ho0.5Er0.5 single crystal in the basal plane in the temperature range 4.2-400 K are reported. The measurements were carried out by the method of flexural autovibrations of a thin sample with sound frequenc...

  1. Changes in structural stability with soil surface degradation. Consequences for soil erosion processes

    OpenAIRE

    Darboux, Frédéric; Le Bissonnais, Yves

    2006-01-01

    Hydrological Science, section 39 - Soil Science Systems, section 23: Dryland hydrologySRef-ID: 1607-7962/gra/EGU06-A-07243; Erosion and sediment transport processes depend on the soil surface properties. Because of water flow and other processes (climate, agricultural practices, biological activity, etc.), the properties of the soil surface can undergo significant changes that affect erosion. As a consequence, understanding of the transport processes and improvement in soil erosion prediction...

  2. Bulk transport and oxygen surface exchange of the mixed ionic electronic conductor Ce1-xTbxO2-δ (x= 1⁄4, 0.1, 0.2, 0.5)

    NARCIS (Netherlands)

    Balaguer Ramirez, M.; Yoo, C.-Y.; Bouwmeester, H.J.M.; Serra, J.M.

    2013-01-01

    Bulk ionic and electronic transport properties and the rate of oxygen surface exchange of Tb-doped ceria have been evaluated as a function of Tb concentration, aiming to assess the potential use of the materials as high-temperature oxygen-transport membranes and oxygen reduction catalysts. The mater

  3. Solid state synthesis and characterization of bulk FeTe0.5Se0.5 superconductors

    Science.gov (United States)

    Onar, K.; Yakinci, M. E.

    2016-01-01

    FeTe0.5Se0.5 polycrystalline superconductor samples were synthesized by solid- state reaction method at different heating temperatures. The morphological and structural characterization of FeTe0 5Se0.5 samples were carried out by X-rays Diffraction, Scanning Electron Microscope and Energy Dispersive X-ray Spectroscopy. The electrical, magnetic and thermal transport properties were investigated up to 8 T by using physical property measurement system. The results reveal that the sensitivity of electrical and magnetic properties strongly depends on the heat treatment cycles. The upper critical field, Hc2(0), was determined with the magnetic field parallel to the sample surface. It gives a maximum value of 36.3 T. The lower critical field, Hc1(T), was obtained as 210, 140 and 70 Oe at 5, 8 and 12 K, respectively. The coherence length, ξ, at the zero field, was calculated to be 1.94 nm and suggested a transparent intergrain boundaries peculiarity. The μ0Hc2(0)/kBTc rate shows higher value (3.36 T/K) than the Pauli limit (1.84 T/K) which suggests unconventional nature of superconductivity for the polycrystalline FeTe0.5Se0.5 superconducting samples.

  4. Soil Carbon Dioxide Production and Surface Fluxes: Subsurface Physical Controls

    Science.gov (United States)

    Risk, D.; Kellman, L.; Beltrami, H.

    Soil respiration is a critical determinant of landscape carbon balance. Variations in soil temperature and moisture patterns are important physical processes controlling soil respiration which need to be better understood. Relationships between soil respi- ration and physical controls are typically addressed using only surface flux data but other methods also exist which permit more rigorous interpretation of soil respira- tion processes. Here we use a combination of subsurface CO_{2} concentrations, surface CO_{2} fluxes and detailed physical monitoring of the subsurface envi- ronment to examine physical controls on soil CO_{2} production at four climate observatories in Eastern Canada. Results indicate that subsurface CO_{2} produc- tion is more strongly correlated to the subsurface thermal environment than the surface CO_{2} flux. Soil moisture was also found to have an important influence on sub- surface CO_{2} production, particularly in relation to the soil moisture - soil profile diffusivity relationship. Non-diffusive profile CO_{2} transport appears to be im- portant at these sites, resulting in a de-coupling of summertime surface fluxes from subsurface processes and violating assumptions that surface CO_{2} emissions are the result solely of diffusion. These results have implications for the study of soil respiration across a broad range of terrestrial environments.

  5. The global distribution and dynamics of surface soil moisture

    Science.gov (United States)

    McColl, Kaighin A.; Alemohammad, Seyed Hamed; Akbar, Ruzbeh; Konings, Alexandra G.; Yueh, Simon; Entekhabi, Dara

    2017-01-01

    Surface soil moisture has a direct impact on food security, human health and ecosystem function. It also plays a key role in the climate system, and the development and persistence of extreme weather events such as droughts, floods and heatwaves. However, sparse and uneven observations have made it difficult to quantify the global distribution and dynamics of surface soil moisture. Here we introduce a metric of soil moisture memory and use a full year of global observations from NASA's Soil Moisture Active Passive mission to show that surface soil moisture--a storage believed to make up less than 0.001% of the global freshwater budget by volume, and equivalent to an, on average, 8-mm thin layer of water covering all land surfaces--plays a significant role in the water cycle. Specifically, we find that surface soil moisture retains a median 14% of precipitation falling on land after three days. Furthermore, the retained fraction of the surface soil moisture storage after three days is highest over arid regions, and in regions where drainage to groundwater storage is lowest. We conclude that lower groundwater storage in these regions is due not only to lower precipitation, but also to the complex partitioning of the water cycle by the surface soil moisture storage layer at the land surface.

  6. Design and mechanism of cost-effective and highly efficient ultrathin (< 0.5 μm GaAs solar cells employing nano/micro-hemisphere surface texturing

    Directory of Open Access Journals (Sweden)

    J. S. Li

    2013-03-01

    Full Text Available Low aspect-ratio nano/micro-hemisphere surface texturing is introduced for improving light management in ultrathin GaAs solar cells. A 200 nm thick film textured by the optimal GaAs nano/micro-hemisphere array with both the hemisphere diameter and array periodicity of 500 nm can achieve >90% light absorption from 1.44 to 2.5 eV, lying in the high photon density energy regime of the solar spectrum for GaAs. The excellent light confinement and low aspect ratio, which is thus convenient for conformal deposition of electrodes for efficient photogenerated carrier collection of the proposed structure will facilitate realization of highly efficient and cost-effective ultrathin GaAs solar cells.

  7. Uptake of gaseous formaldehyde onto soil surfaces: a coated-wall flow tube study

    Science.gov (United States)

    Li, Guo; Su, Hang; Li, Xin; Meusel, Hannah; Kuhn, Uwe; Pöschl, Ulrich; Shao, Min; Cheng, Yafang

    2015-04-01

    Gaseous formaldehyde (HCHO) is an important intermediate molecule and source of HO2 radicals. However, discrepancies exist between model simulated and observed HCHO concentrations, suggesting missing sources or sinks in the HCHO budget. Multiphase processes on the surface of soil and airborne soil-derived particles have been suggested as an important mechanism for the production/removal of atmospheric trace gases and aerosols. In this work, the uptake of gaseous HCHO on soil surfaces were investigated through coated-wall flow tube experiments with HCHO concentration ranging from 10 to 40 ppbv. The results show that the adsorption of HCHO occurred on soil surfaces, and the uptake coefficient dropped gradually (i.e., by a factor of 5 after 1 hour) as the reactive surface sites were consumed. The HCHO uptake coefficient was found to be affected by the relative humidity (RH), decreasing from (2.4 ± 0.5) × 10-4 at 0% RH to (3.0 ± 0.08) × 10-5 at 70% RH, due to competition of water molecule absorption on the soil surface. A release of HCHO from reacted soil was also detected by applying zero air, suggesting the nature of reversible physical absorption and the existence of an equilibrium at the soil-gas interface. It implies that soil could be either a source or a sink for HCHO, depending on the ambient HCHO concentration. We also develop a Matlab program to calculate the uptake coefficient under laminar flow conditions based on the Cooney-Kim-Davis method.

  8. Ethylbenzene dehydrogenation over Mg3Fe0.5−xCoxAl0.5 catalysts derived from hydrotalcites: Comparison with Mg3Fe0.5−yNiyAl0.5 catalysts

    KAUST Repository

    Atanda, Luqman A.

    2011-04-01

    A series of Mg3Fe0.5-xCoxAl0.5 (x = 0-0.5) catalysts were prepared from hydrotalcite precursors and their activities in the dehydrogenation of ethylbenzene were compared with those of a series of Mg3Fe0.5-yNiyAl0.5 (y = 0-0.5) catalysts also derived from hydrotalcite. The hydrotalcites prepared by co-precipitation were calcined at 550 °C to the mixed oxides with a high surface area of 150-240m2gcat-1; they were composed of Mg(Fe,Me,Al)O periclase and Mg(Me)(Fe,Al)2O4 spinel (Me = Co or Ni). Bimetallic Fe3+-Co2+ system showed a synergy, i.e., an increase in the activity, whereas Fe3+-Ni2+ bimetallic system showed no synergy. The high styrene yield was obtained on Mg 3Fe0.1Co0.4Al0.5; however, a large substitution of Fe3+ with Co2+ caused a decrease in styrene selectivity along with coking on the catalysts, due to an isolation of CoOx on the catalyst surface. The highest yield as well as the highest selectivity for styrene production was obtained at x = 0.25 at time on stream of 30 min. The coprecipitation at pH = 10.0 and the composition of Mg3Fe0.25Co0.25Al0.5 were the best for preparing the active catalyst. This is partly due to the formation of a good hydrotalcite structure. On this catalyst, the active Fe3+ species was reduced at a low temperature by the Fe3+-Co2+ bimetal formation, leading to a high activity. Simultaneously, the amount of reducible Fe3+ was the smallest, resulting in a high stability of the active Fe3+ species. It is likely that the dehydrogenation was catalyzed by the reduction-oxidation between Fe3+ and Fe2+ and that Co2+ assisted the reduction-oxidation by forming Fe 3+-Co2+ (1/1) bimetallic active species. © 2011 Elsevier B.V. All rights reserved.

  9. Metamagnetic Transitions in La_{0.5} Pr_{0.5} Mn_2 Si_2

    Science.gov (United States)

    Duman, Eyüp; Acet, Mehmet; Krenke, Thorsten; Ouladdiaf, Bachir; Suard, Emmanual

    2017-01-01

    La_{0.5} Pr_{0.5} Mn_2 Si_2 undergoes an antiferromagnetic-ferromagnetic transition at about 250 K (-23° C). This transition can also be induced by an external magnetic field leading to a metamagnetic transition. This can lead to a large change in the magnetic entropy, which is useful for magnetic cooling and studying the magnetocaloric effect. We investigated the details of the spin configuration as the magnetic ordering progresses from AF to FM by neutron diffraction techniques under magnetic fields up to 5 T and using spectral refining methods.

  10. Superhard W0.5Ta0.5B nanowires prepared at ambient pressure

    Science.gov (United States)

    Yeung, Michael T.; Akopov, Georgiy; Lin, Cheng-Wei; King, Daniel J.; Li, Rebecca L.; Sobell, Zachary C.; Mohammadi, Reza; Kaner, Richard B.

    2016-11-01

    The primary focus of superhard materials development has relied on chemical tuning of the crystal structure. While these intrinsic effects are invaluable, there is a strong possibility that hardness can be dramatically enhanced using extrinsic effects. Here, we demonstrate that the superhard metal W0.5Ta0.5B can be prepared as nanowires through flux growth. The aspect ratios of the nanowires are controlled by the concentration of boride in molten aluminum, and the nanowires grow along the boron-boron chains, confirmed via electron diffraction. This morphology inherently results from the crystal habit of borides and can inspire the development of other nanostructured materials.

  11. Surface Reactivity in Tropical Highly Weathered Soils and Implications for Rational Soil Management

    Institute of Scientific and Technical Information of China (English)

    R. MOREAU; J. PETARD

    2004-01-01

    Highly weathered soils are distributed in the humid and wet-dry tropics, as well as in the humid subtropics. As a result of strong weathering, these soils are characterized by low activity clays, which develop variable surface charge and related specific properties. Surface reactions regarding base exchange and soil acidification, heavy metal sorption and mobility, and phosphorus sorption and availability of the tropical highly weathered soils are reviewed in this paper.Factors controlling surface reactivity towards cations and anions, including ion exchange and specific adsorption processes, are discussed with consideration on practical implications for rational management of these soils. Organic matter content and pH value are major basic factors that should be controlled through appropriate agricultural practices, in order to optimise favorable effects of colloid surface properties on soil fertility and environmental quality.

  12. Reflectance anisotropy for characterising fine-scale changes in soil surface condition across different soil types

    Science.gov (United States)

    Croft, Holly; Anderson, Karen; Kuhn, Nikolaus J.

    2010-05-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in a reduction in soil productivity, an increased susceptibility to erosion and increased release of greenhouse gases. Soil surface roughness at the centimetre scale plays a fundamental role in affecting soil erosion and surface runoff pathways. A decline in surface roughness can also be used to infer soil degradation as soil aggregates are broken down through raindrop impact. However, due to the time and resources involved in using traditional field sampling techniques, there is a lack of spatially-distributed information on soil surface condition. Remotely sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Furthermore, a growing recognition into the importance of the directional reflectance domain has led to an increasing number of satellites with multiple view angle (MVA) capabilities (e.g. MISR, CHRIS on Proba). This is potentially useful for monitoring soil degradation and susceptibility to erosion because changes in soil surface roughness, associated with the breakdown of macro-aggregates, have a measurable effect on directional reflectance factors. Consequently, field and laboratory data are required for an empirical understanding of soil directional reflectance characteristics, underpinning subsequent model development. This study assessed the extent to which a hyperspectral MVA approach (350-2500 nm) could detect fine-scale changes in soil crusting states across five different soil types. A series of soil crusting states were produced for all five soil types, using an artificial rainfall simulator. The controlled conditions allowed the production of a series of stages in the soil crusting process; showing progressively declining surface roughness values. Each soil state was then spatially characterised, using a laboratory laser device at 2 mm sample spacing, over a 10 x 10 cm area. Laser data

  13. Corrosion and Serration Behaviors of TiZr0.5NbCr0.5VxMoy High Entropy Alloys in Aqueous Environments

    Directory of Open Access Journals (Sweden)

    Jiemin Li

    2014-12-01

    Full Text Available The corrosion and serration behaviors of TiZr0.5NbCr0.5, TiZr0.5NbCr0.5V and TiZr0.5NbCr0.5Mo high entropy alloys (HEAs in NaCl and H2SO4 solutions were studied by potentiodynamic polarizations (PP and immersion tests. The results show that all the alloys display excellent corrosion resistance no matter in NaCl solution or in H2SO4 solution. The additions of V and Mo increase the pitting corrosion resistance for the three alloys in NaCl solution slightly and greatly improve the corrosion resistance in H2SO4 solution. The corrosion behaviors of TiZr0.5NbCr0.5 and TiZr0.5NbCr0.5Mo alloys are more sensitive to temperature than that of TiZr0.5NbCr0.5V alloy. After immersion, the surface of TiZr0.5NbCr0.5 alloy appears some pitting holes, this may be related to the electrochemical noise and serration behavior on PP curves; localized corrosion initiates mainly on the boundaries of the BCC and Cr2Zr Laves phase for TiZr0.5NbCr0.5V alloy; while for the TiZr0.5NbCr0.5Mo alloy, the dendrites with Mo element rich region exhibit poor corrosion resistance.

  14. Visually assessing the level of development and soil surface stability of cyanobacterially dominated biological soil crusts

    Science.gov (United States)

    Belnap, J.; Phillips, S.L.; Witwicki, D.L.; Miller, M.E.

    2008-01-01

    Biological soil crusts (BSCs) are an integral part of dryland ecosystems and often included in long-term ecological monitoring programs. Estimating moss and lichen cover is fairly easy and non-destructive, but documenting cyanobacterial level of development (LOD) is more difficult. It requires sample collection for laboratory analysis, which causes soil surface disturbance. Assessing soil surface stability also requires surface disturbance. Here we present a visual technique to assess cyanobacterial LOD and soil surface stability. We define six development levels of cyanobacterially dominated soils based on soil surface darkness. We sampled chlorophyll a concentrations (the most common way of assessing cyanobacterial biomass), exopolysaccharide concentrations, and soil surface aggregate stability from representative areas of each LOD class. We found that, in the laboratory and field, LOD classes were effective at predicting chlorophyll a soil concentrations (R2=68-81%), exopolysaccharide concentrations (R2=71%), and soil aggregate stability (R2=77%). We took representative photos of these classes to construct a field guide. We then tested the ability of field crews to distinguish these classes and found this technique was highly repeatable among observers. We also discuss how to adjust this index for the different types of BSCs found in various dryland regions.

  15. Soil Surface Structure: A key factor for the degree of soil water repellency

    Science.gov (United States)

    Ahn, S.; Doerr, S. H.; Douglas, P.; Bryant, R.; Hamlett, C.; McHale, G.; Newton, M.; Shirtcliffe, N.

    2012-04-01

    Despite of considerable efforts, the degree of water repellency has not always been fully explained by chemical property of soil (termed hydrophobicity). That might be because the structure of a soil surface was not considered properly, which is another main factor determining the severity of soil water repellency. Surface structure has only recently been considered in soil science, whilst it has been paid attention for several decades in materials science due to its relevance to industrial applications. In this contribution, comparison of critical contact angles measured on different surface structures (made with glass beads, glass shards and beach sands) is presented and the effect of surface structure on manifestation of soil water repellency is discussed in terms of several different variables such as the individual particles shape, and areal and structural factors of the actual surface.

  16. Liquid Spills on Permeable Soil Surfaces: Experimental Confirmations

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Carver S.; Keller, Jason M.

    2005-09-29

    Predictive tools for assessing the quantity of a spill on a soil from the observed spreading area could contribute to improving remediation when it is necessary. On a permeable soil, the visible spill area only hints about the amount of liquid that might reside below the surface. An understanding of the physical phenomena involved with spill propagation on a soil surface is key to assessing the liquid amount possibly present beneath the surface. The objective of this study is an improved prediction capability for spill behavior.

  17. Phonon spectra of La0.5Ca0.5MnO3

    Institute of Scientific and Technical Information of China (English)

    Cao Xian-Sheng; Chen Chang-Le

    2009-01-01

    This paper presents a microscopic theory to explain different Raman modes of La0.5Ca0.5MnO3 based on the electronic Hamiltonian of the Kondo lattice model, which adds phonon interaction to the hybridization between the conduction electrons of the system and the l-electrons. The spectral density is calculated by the Green function technique of Zubarev at zero wave vector and in the low temperature limit. It finds that there are three Raman-active modes and the spectral densities of these modes are substantially influenced by model parameters such as the position of Mevel (εJT), the effective electron-phonon coupling strength (g) and the hybridization parameter (v). Finally, the intensity changes of those peaks are investigated.

  18. Soil Surface Sealing Effect on Soil Moisture at a Semiarid Hillslope: Implications for Remote Sensing Estimation

    Directory of Open Access Journals (Sweden)

    Shai Sela

    2014-08-01

    Full Text Available Robust estimation of soil moisture using microwave remote sensing depends on extensive ground sampling for calibration and validation of the data. Soil surface sealing is a frequent phenomenon in dry environments. It modulates soil moisture close to the soil surface and, thus, has the potential to affect the retrieval of soil moisture from microwave remote sensing and the validation of these data based on ground observations. We addressed this issue using a physically-based modeling approach that accounts explicitly for surface sealing at the hillslope scale. Simulated mean soil moisture at the respective layers corresponding to both the ground validation probe and the radar beam’s typical effective penetration depth were considered. A cyclic pattern was found in which, as compared to an unsealed profile, the seal layer intensifies the bias in validation during rainfall events and substantially reduces it during subsequent drying periods. The analysis of this cyclic pattern showed that, accounting for soil moisture dynamics at the soil surface, the optimal time for soil sampling following a rainfall event is a few hours in the case of an unsealed system and a few days in the case of a sealed one. Surface sealing was found to increase the temporal stability of soil moisture. In both sealed and unsealed systems, the greatest temporal stability was observed at positions with moderate slope inclination. Soil porosity was the best predictor of soil moisture temporal stability, indicating that prior knowledge regarding the soil texture distribution is crucial for the application of remote sensing validation schemes.

  19. The effect of heterogeneity and surface roughness on soil hydrophobicity

    Science.gov (United States)

    Hallin, I.; Bryant, R.; Doerr, S. H.; Douglas, P.

    2010-05-01

    Soil water repellency, or hydrophobicity, can develop under both natural and anthropogenic conditions. Forest fires, vegetation decomposition, microbial activity and oil spills can all promote hydrophobic behaviour in surrounding soils. Hydrophobicity can stabilize soil organic matter pools and decrease evapotranspiration, but there are many negative impacts of hydrophobicity as well: increased erosion of topsoil, an increasingly scarce resource; increased runoff, which can lead to flooding; and decreased infiltration, which directly affects plant health. The degree of hydrophobicity expressed by soil can vary greatly within a small area, depending partly on the type and severity of the disturbance as well as on temporal factors such as water content and microbial activity. To date, many laboratory investigations into soil hydrophobicity have focused on smooth particle surfaces. As a result, our understanding of how hydrophobicity develops on rough surfaces of macro, micro and nano-particulates is limited; we are unable to predict with certainty how these soil particles will behave on contact with water. Surface chemistry is the main consideration when predicting hydrophobic behaviour of smooth solids, but for particles with rough surfaces, hydrophobicity is believed to develop as a combination of surface chemistry and topography. Topography may reflect both the arrangement (aggregation) of soil particles and the distribution of materials adsorbed on particulate surfaces. Patch-wise or complete coverage of rough soil particles by hydrophobic material may result in solid/water contact angles ≥150° , at which point the soil may be classified as super-hydrophobic. Here we present a critical review of the research to date on the effects of heterogeneity and surface roughness on soil hydrophobicity in which we discuss recent advances, current trends, and future research areas. References: Callies, M., Y. Chen, F. Marty, A. Pépin and D. Quéré. 2005. Microfabricated

  20. SMAP Level 4 Surface and Root Zone Soil Moisture

    Science.gov (United States)

    Reichle, R.; De Lannoy, G.; Liu, Q.; Ardizzone, J.; Kimball, J.; Koster, R.

    2017-01-01

    The SMAP Level 4 soil moisture (L4_SM) product provides global estimates of surface and root zone soil moisture, along with other land surface variables and their error estimates. These estimates are obtained through assimilation of SMAP brightness temperature observations into the Goddard Earth Observing System (GEOS-5) land surface model. The L4_SM product is provided at 9 km spatial and 3-hourly temporal resolution and with about 2.5 day latency. The soil moisture and temperature estimates in the L4_SM product are validated against in situ observations. The L4_SM product meets the required target uncertainty of 0.04 m(exp. 3)m(exp. -3), measured in terms of unbiased root-mean-square-error, for both surface and root zone soil moisture.

  1. Formation and development of salt crusts on soil surfaces

    KAUST Repository

    Dai, Sheng

    2015-12-14

    The salt concentration gradually increases at the soil free surface when the evaporation rate exceeds the diffusive counter transport. Eventually, salt precipitates and crystals form a porous sodium chloride crust with a porosity of 0.43 ± 0.14. After detaching from soils, the salt crust still experiences water condensation and salt deliquescence at the bottom, brine transport across the crust driven by the humidity gradient, and continued air-side precipitation. This transport mechanism allows salt crust migration away from the soil surface at a rate of 5 μm/h forming salt domes above soil surfaces. The surface characteristics of mineral substrates and the evaporation rate affect the morphology and the crystal size of precipitated salt. In particular, substrate hydrophobicity and low evaporation rate suppress salt spreading.

  2. 7Be:A Geochemical Tracer for Seasonal Erosion of Surface Soil in Watershed of Lake Hongfeng,Guizahou ,China

    Institute of Scientific and Technical Information of China (English)

    BAIZHANGUO; P.H.SANTSCHI; 等

    1996-01-01

    7Be penetrative depth in undisturbed surface soil is within 4mm.7Be activity shows exponential decrease with soil depth,which is expressed as a diffusion process.7Be penetrative depth in undisturbed surface soil is apparently deeper in the fall (0.22-0.37g cm-1) than in the spring (0.11-0.28g cm-2) at the same site;Whereas,7Be apparent activity at the top of surface soil is higher in the spring (0.3-2.2Bq g-1)than in the fall (0.2-0.5Bqg-1) at the same site,The 7Be inventory(189-544Bq m-2)changes with both locations and seasons.Although the 7Be flux to the earth's surface increases with amount of precipitation,its maximum inventory in the soil profiles decreases to 30%-40% after the rainy period.Calculated by the diffusion equation,the erosion and accumulation rates of soil particles are agreeable with the observation in situ,Which shows that the rates in fall are 1.5 times those in spring.The eroded soil particles almost all have been removed on the tablelands rathel than transported into the drainage system.This indicates that the soil erosion process in the karst region is only partial transportation within a short distance.

  3. Structural and Optical Properties of GaAs0.5Sb0.5 and In0.5Ga0.5As0.sSb0.5:ab initio Calculations for Pure and Doped Materials

    Institute of Scientific and Technical Information of China (English)

    Mazin SH.Othman; Khudheir A.Mishjil; Nadir F.Habubi

    2012-01-01

    We perform a first-principles study to evaluate the structural,electronic and optical properties of GaAsxSb1-x ternary and InyGa1-yAsxSb1-x quaternary semiconductor alloys up to x =0.5,y =0.5. We employ the Perdew-Burke-Ernzerhof form of the generalized gradient approximation (GGA) within the framework of density functional theory (DFT) by using a simulation program.Calculations are carried out in different configurations.For these alloys,lattice parameters and optical band gap energy are calculated. The optical band gaps varywith increasing and decreasing As and In concentrations,respectively.The optical conductivity,absorption and the real part of the dielectric function ε1 (ω) are discussed. Our results agree well with the theoretical and experimental data available in the literature.

  4. Phase transitions in Fe{sub 0.5}Co{sub 0.5} (110) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Dámaso, G., E-mail: gramirezd@ipn.mx [Escuela Superior de Ingeniería y Arquitectura “Unidad Ticomán” del Instituto Politécnico Nacional, Av. Ticomán No. 600, Col. San José Ticomán, Del. G. A. M., C. P. 07330 Ciudad de México (Mexico); Castillo-Alvarado, F.L. [Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, Edificio 9, Col. San Pedro Zacatenco, C. P. 07738 Ciudad de México (Mexico); Rojas-Hernández, E. [Escuela Superior de Ingeniería y Arquitectura “Unidad Ticomán” del Instituto Politécnico Nacional, Av. Ticomán No. 600, Col. San José Ticomán, Del. G. A. M., C. P. 07330 Ciudad de México (Mexico)

    2016-12-15

    In this paper, we present calculations for two second-order phase transitions in (110) Fe{sub 0.5}Co{sub 0.5} thin films with 11, 15, and 19 monoatomic layers. The lattice and magnetic transitions are based on thermodynamic equilibrium considerations of the magnetic alloy. The procedure proposed by Valenta and Sukiennicki was applied to calculate the composition x(i), the lattice order parameter t(i), and the magnetic order parameter σ(i) as a function of temperature T. We confirmed that both phase transitions, lattice and magnetic, are of the second order, in accordance with experimental results in the literature. The obtained behavior of these parameters indicates their inhomogeneity due to the boundary conditions on the surfaces of the thin film.

  5. Effect of Management Practices on Soil Microstructure and Surface Microrelief

    Directory of Open Access Journals (Sweden)

    R. Garcia Moreno

    2012-01-01

    Full Text Available Soil surface roughness (SSR and porosity were evaluated from soils located in two farms belonging to the Plant Breeding Institute of the University of Sidney. The sites differ in their soil management practices; the first site (PBI was strip-tilled during early fall (May 2010, and the second site (JBP was under power harrowed tillage at the end of July 2010. Both sites were sampled in mid-August. At each location, SSR was measured for three 1 m2 subplots using shadow analysis. To evaluate porosity and aggregation, soil samples were scanned using X-ray computed tomography with 5 μm resolution. The results show a strong negative correlation between SSR and porosity, 20.13% SSR and 41.38% porosity at PBI versus 42.00% SSR and 18.35% porosity at JBP. However, soil images show that when soil surface roughness is higher due to conservation and soil management practices, the processes of macroaggregation and structural porosity are enhanced. Further research must be conducted on SSR and porosity in different types of soils, as they provide complementary information on the evaluation of soil erosion susceptibility.

  6. Electron-phonon superconductivity in LaO{sub 0.5}F{sub 0.5}BiSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yanqing; Du, Yongping; Wan, Xiangang, E-mail: xgwan@nju.edu.cn; Wang, Bogen [Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Ding, Hang-Chen [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200062 (China); Savrasov, Sergey Y. [Department of Physics, University of California, Davis, One Shields Avenue, Davis, California 95616 (United States); Duan, Chun-Gang [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200062 (China); National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2014-06-21

    We report density functional calculations of the electronic structure, Fermi surface, phonon spectrum and electron–phonon coupling for the newly discovered superconductor LaO{sub 0.5}F{sub 0.5}BiSe{sub 2}. It is confirmed that there is a strong Fermi surface nesting at (π,π,0), which results in unstable phonon branches. Combining the frozen phonon total energy calculations and an anharmonic oscillator model, we find that the quantum fluctuation prevents the appearance of static long–range order. The calculation shows that LaO{sub 0.5}F{sub 0.5}BiSe{sub 2} is highly anisotropic, and same as its cousin LaO{sub 0.5}F{sub 0.5}BiS{sub 2}, this compound is also a conventional electron-phonon coupling induced superconductor.

  7. Structural characterization of layered Na0.5Co0.5Mn0.5O2 material as a promising cathode for sodium-ion batteries

    Science.gov (United States)

    Manikandan, Palanisamy; Heo, Seongwoo; Kim, Hyun Woo; Jeong, Hu Young; Lee, Eungje; Kim, Youngsik

    2017-09-01

    Layered Na0.5Co0.5Mn0.5O2 material is synthesized through a facile mixed hydroxy-carbonate route using (Co0.5Mn0.5)2(OH)2CO3 precursor and well characterized as a hexagonal layered structure under P63/mmc space group. The lattice parameters and unit cell volume (a = 2.8363 Å, c = 11.3152 Å and V = 78.83 Å3) are calculated by Rietveld refinement analysis. A flaky-bundle morphology is obtained to the layered Na0.5Co0.5Mn0.5O2 material with the hexagonal flake size ∼30 nm. Advanced transmission electron microscopic images are revealed the local structure of the layered Na0.5Co0.5Mn0.5O2 material with contrasting bright dots and faint dark dots corresponding to the Co/Mn and Na atoms. Two oxidation and reduction peaks are occurred in a cyclic voltammetric analysis corresponding to Co3+/Co4+ and Mn3+/Mn4+ redox processes. These reversible processes are attributed to the intercalation/de-intercalation of Na+ ions into the host structure of layered Na0.5Co0.5Mn0.5O2 material. Accordingly, the sodium cell is delivered the initial charge-discharge capacity 53/144 mAh g-1 at 0.5 C, which cycling studies are extended to rate capability test at 1 C, 3 C and 5C. Eventually, the Na-ion full-cell is yielded cathode charge-discharge capacity 55/52 mAh g-1 at 0.212 mA and exhibited as a high voltage cathode for Na-ion batteries.

  8. Preparation of Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2}/cotton catalysts for decomposition of formaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xuehua; He, Junhui, E-mail: jhhe@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (CAS), Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials (China); Wang, Donghui [Research Institute of Chemical Defense (China); Hu, Yucai [Ludong University, School of Chemistry and Materials Science (China); Tian, Hua [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (CAS), Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials (China); Dong, Tongxin [Research Institute of Chemical Defense (China); He, Zhicheng [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (CAS), Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials (China)

    2013-08-15

    Powder Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2} and Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2}/cotton catalysts were successfully prepared by facile methods. The as-prepared catalysts were characterized by means of XRD, SEM, TEM, and TGA. Au{sub 0.5}Pt{sub 0.5} alloy NPs were evenly dispersed on the surface of nest-like MnO{sub 2} and no agglomeration was observed. The powder Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2} catalyst was adhered to the surface of cotton fibers, and the practical loading amount first increases, and then levels off with increase of the theoretical loading dosage. The Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2}/cotton catalysts showed excellent catalytic activities for oxidative decomposition of formaldehyde (HCHO). 15 wt% Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2}/cotton has the highest catalytic activity and the temperature for complete decomposition of HCHO is 120 Degree-Sign C. The valence states of MnO{sub 2}, MnO{sub 2} porous structures, synergistic effect between Au{sub 1-x}Pt{sub x} NPs and MnO{sub 2}, and synergistic effect between Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2} and cotton are considered to be the main reasons for the observed high catalytic activity of Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2}/cotton catalysts. The Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2}/cotton catalysts can not only avoid the disadvantages of power catalysts but also improve the catalytic activity; these advantages indicate that Au{sub 0.5}Pt{sub 0.5}/MnO{sub 2}/cotton catalysts have promising potentials in practical applications.Graphical Abstract.

  9. Soil Organic Matter and Soil Productivity: Searching for the Missing Link

    Science.gov (United States)

    Felipe G. Sanchez

    1998-01-01

    Soil-organic matter (SOM) is a complex array of components including soil fauna and flora at different stages of decomposition (Berg et al., 1982). Its concentration in soils can vary from 0.5% in mineral soils to almost 100% in peat soils (Brady, 1974). Organic matter (OM) in the surface mineral soil is considered a major determinant of forest ecosystem productivity...

  10. Experimental demonstration of Martian soil simulant removal from a surface using a pulsed plasma jet.

    Science.gov (United States)

    Ticoş, C M; Scurtu, A; Toader, D; Banu, N

    2015-03-01

    A plasma jet produced in a small coaxial plasma gun operated at voltages up to 2 kV and working in pure carbon dioxide (CO2) at a few Torr is used to remove Martian soil simulant from a surface. A capacitor with 0.5 mF is charged up from a high voltage source and supplies the power to the coaxial electrodes. The muzzle of the coaxial plasma gun is placed at a few millimeters near the dusty surface and the jet is fired parallel with the surface. Removal of dust is imaged in real time with a high speed camera. Mars regolith simulant JSC-Mars-1A with particle sizes up to 5 mm is used on different types of surfaces made of aluminium, cotton fabric, polyethylene, cardboard, and phenolic.

  11. Experimental demonstration of Martian soil simulant removal from a surface using a pulsed plasma jet

    Science.gov (United States)

    Ticoş, C. M.; Scurtu, A.; Toader, D.; Banu, N.

    2015-03-01

    A plasma jet produced in a small coaxial plasma gun operated at voltages up to 2 kV and working in pure carbon dioxide (CO2) at a few Torr is used to remove Martian soil simulant from a surface. A capacitor with 0.5 mF is charged up from a high voltage source and supplies the power to the coaxial electrodes. The muzzle of the coaxial plasma gun is placed at a few millimeters near the dusty surface and the jet is fired parallel with the surface. Removal of dust is imaged in real time with a high speed camera. Mars regolith simulant JSC-Mars-1A with particle sizes up to 5 mm is used on different types of surfaces made of aluminium, cotton fabric, polyethylene, cardboard, and phenolic.

  12. EPIDURAL ANESTHESIA BUPIVACAINE 0.5%+ KCL 5 MEQ/L VS BUPIVACAINE 0.5%

    Directory of Open Access Journals (Sweden)

    F ALAVI

    2000-03-01

    Full Text Available Background. Although epidural anesthesia is a Successful method for most surgical procedures on lower extremities and lower abdomen. It is not so favorable because of it's slow onset and differential sensory and motor block. In order to solve this problem effects of additive KCl (5 meq/L into Bupivacaine 0.5 percent according to onset, intensity, duration of block and homodynamic changes during epidural anesthesia will be investigated through the present study. Methods. All the ASA I or II patients at medical centers of Isfahan university of medical sciences throughout 1378, candidate for elective Surgical procedures on lower extremities and lower abdomen with no contraindication for epidural anesthesia were Subdivided into Case (35 patients and Control (35 patients groups in a random manner to perform a double blind clinical trial. Epidural anesthesia applied to cases (by Bupivacaine 0.5 percent+ KCl 5meq/L and controls (by Bupivacaine 0.5 percent. Under identical conditions, data indicating basic MAP, basic heart rate and their changes as well as the onset, duration and intensity of motor and sensory block, were obtained and recorded by the anesthesiologist. Quantitative & qualitative variables were examined by T.test and X2 test respectively. Findings. Sensory onset for cases (8.22±1.43Min was faster than controls (11.56±1.45Min (P<0.005. Motor onset for cases (12.77 ± 1.83Min was faster than controls (20.24±1.71Min (P < 0.005. Sensory duration for cases (l86.34±8.37 Min was longer than controls (162.17±7.47Min (P<0.005. Motor duration for cases (106.25±13.50 Min was longer than controls (77.60 ± 9.94Min (P < 0.005.Intensity of sensory block for cases was greater than controls (P < 0.01. Intensity of motor block for cases was greater than controls (P < 0.001. Mean heart rate changes for cases (7.28±9.37 percent and controls (7 ± 8 percent were not different (P < 0.8. Mean decrease in MAP for cases (20.17 ± 2.10n percent was

  13. Efficacy and safety of 0.5% levobupivacaine versus 0.5% bupivacaine for peribulbar anesthesia

    Directory of Open Access Journals (Sweden)

    Pacella E

    2013-05-01

    Full Text Available Elena Pacella,1 Fernanda Pacella,1 Fabiana Troisi,2 Domenico Dell'Edera,3 Paolo Tuchetti,4 Tommaso Lenzi,1 Saul Collini21Department of Sense Organs, Faculty of Medicine and Dentistry, Rome, 2Department of Medical Surgical Sciences and Translational Medicine Sapienza, Faculty of Medicine and Psychology, Roma, University of Rome, Rome, 3Unit of Cytogenetic and Molecular Genetics, Madonna delle Grazie Hospital, Matera, 4National Institute for Health, Migration and Poverty, Rome, ItalyBackground: This randomized double-blind study examined the use of a new anesthetic agent, levobupivacaine 0.5%, which is the S(−-enantiomer of a racemic mixture of bupivacaine, for peribulbar anesthesia and compared it with racemic bupivacaine 0.5% alone or in combination with hyaluronidase 10 IU/mL.Methods: A total of 160 patients undergoing ophthalmic surgery were randomized into four groups (n = 40 each to receive inferotemporal peribulbar injection of levobupivacaine 0.5% (group L, racemic bupivacaine 0.5% (group B, levobupivacaine + hyaluronidase 10 IU/mL (group LH, or racemic bupivacaine + hyaluronidase 10 IU/mL (group BH by two anesthetists and two ophthalmologists in a ratio of 25% each. Ocular akinesia and orbicularis oculi function were evaluated using a three-point scale; a value < 5 points was considered as requiring surgery, and movements were re-evaluated the day following surgery to confirm regression of the block.Results: The time to onset (12 ± 2.6 minutes versus 13 ± 2.8 minutes and duration of anesthesia (185 ± 33.2 minutes versus 188 ± 35.7 minutes were similar between groups L and B. Complete akinesia (score 0 was obtained more frequently when hyaluronidase was used in addition to the anesthetic, with occurrences of 72.5% versus 57.5% in group LH versus L, respectively, and 67.5% versus 45% in group BH versus B. Moderate hypotension (<30% of baseline was observed in four patients (10% in group L, two (5.0% in group B, one (2.5% in group LH

  14. Sound absorption at the soil surface

    NARCIS (Netherlands)

    Janse, A.R.P.

    1969-01-01

    The properties of a soil structure may be examined in various manners. As well as a study of the stability, a knowledge of the geometry of the volume of air filled pores is often needed. The most common measurements, like those of porosity and flow resistance to gases do not permit a detailed

  15. Predicting root zone soil moisture using surface data

    Science.gov (United States)

    Manfreda, S.; Brocca, L.; Moramarco, T.; Melone, F.; Sheffield, J.; Fiorentino, M.

    2012-04-01

    In recent years, much effort has been given to monitoring of soil moisture from satellite remote sensing. These tools represent an extraordinary source of information for hydrological applications, but they only provide information on near-surface soil moisture. In the present work, we developed a new formulation for the estimation of the soil moisture in the root zone based on the measured value of soil moisture at the surface. The method derives from a simplified form of the soil water balance equation and for this reason all parameters adopted are physically consistent. The formulation provides a closed form of the relationship between the root zone soil moisture and the surface soil moisture with a limited number of parameters, such as: the ratio between the depth of the surface layer and the deeper layer, the water loss coefficient, and the field capacity. The method has been tested using modeled soil moisture obtained from the North American Land Data Assimilation System (NLDAS). The NLDAS is a multi-institution partnership aimed at developing a retrospective data set, using available atmospheric and land surface meteorological observations to compute the land surface hydrological budget. The NLDAS database was extremely useful for the scope of the present research since it provides simulated data over an extended area with different climatic and physical condition and moreover it provides soil moisture data averaged over different depths. In particular, we used values in the top 10 cm and 100 cm layers. One year of simulation was used to test the ability of the developed method to describe soil moisture fluctuation in the 100cm layer over the entire NLDAS domain. The method was adopted by calibrating one of its three parameters and defining the remaining two based on physical characteristics of the site (using the potential evapotranspiration and ratio between the first and the second soil layer depth). In general, the method performed better than

  16. Titratable Acidity and Alkalinity of Red Soil Surfaces

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; HEQUN; 等

    1993-01-01

    The surfaces of red soils have an apparent amphoteric character,carrying titratable acidity and titratable alkalinity simultaneously.The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxide-type surfaces and dissociation of weak-acid functional groups of soil organic matter,while the titratable alkalinity is derived from release of hydroxyl groups of hydrous oxide-type surfaces.The titratable acidity and titratable alkalinity mainly depended on the composition and content of iron and aluminum oxides in the soils.The results showed that the titratable acidity and titratable alkalinity were in significantly positive correlation not only with the content of amorphous aluminum oxide(Alo) and iron oxide(Feo) extracted with acid ammonium oxalate solution,free iron oxide(Fed) extracted with sodium dithionite-citrate-bicarbonate(DCB) and clays,but also with the zero point of charge (ZPC) of the samples.Organic matter made an important contribution to the titratable acidity.the titratable alkalinity was closely correlated with the amount of fluoride ions adsorbed.The titratable acidity and titratable alkalinity of red soils were influenced by parent materials,being in the order of red soil derived from basalt> that from tuff> that from granite.The titratable acidity and titratable alkalinity ware closely related with origination of the variable charges of red soils,and to a certain extent were responsible for variable negative and positive charges of the soils.

  17. Influence of electron beam irradiation on the structural, electrical and thermal properties of Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 manganites

    Science.gov (United States)

    Nagaraja, B. S.; Rao, Ashok; Babu, P. D.; Sanjeev, Ganesh; Okram, G. S.

    2016-01-01

    We present systematic studies on the effect of electron beam irradiation on structural, electrical and thermal properties of Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 manganites. The XRD patterns and Rietveld analysis show that the samples remain single phased even after they undergo electron beam irradiation. Both the series of the samples Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 show insulating trends in their temperature dependent electrical resistivity, ρ(T) behavior. The resistivity data for both the series of samples (pristine as well as irradiated) indicate that the small polaron hopping model is valid in high temperature region; on contrary, variable range hopping model governs the low temperature regime. Magnetic studies demonstrate that the Neel temperatures of pristine and irradiated samples of Gd0.5Sr0.5MnO3 and Dy0.5Sr0.5MnO3 do not change appreciably when they are subjected to irradiation. Thermo-electrical power is observed to increase with irradiation in Gd0.5Sr0.5MnO3 samples, whereas for Dy0.5Sr0.5MnO3 samples a decrease in thermo-electric power is seen when the samples are irradiated.

  18. Novel Measurement and Monitoring Approaches for Surface and Near-Surface Soil Moisture

    Science.gov (United States)

    Jones, S. B.; Sheng, W.; Zhou, R.; Sadeghi, M.; Tuller, M.

    2015-12-01

    The top inch of the earth's soil surface is a very dynamic and important layer where physical and biogeochemical processes take place under extreme diurnal and seasonal moisture and temperature variations. Some of these critical surfaces include biocrusts, desert pavements, agricultural lands, mine tailings, hydrophobic forest soils, all of which can significantly impact environmental conditions at large-scales. Natural hazards associated with surface conditions include dust storms, post-fire erosion and flooding in addition to crop failure. Less obvious, though continually occurring, are microbial-induced gas emissions that are also significantly impacted by surface conditions. With so much at stake, it is surprising that in today's technological world there are few if any sensors designed for monitoring the top few mm or cm of the soil surface. In particular, remotely sensed data is expected to provide near-real time surface conditions of our Earth, but we lack effective tools to measure and calibrate surface soil moisture. We are developing multiple methods for measurement and monitoring of surface and near-surface soil water content which include gravimetric as well as electromagnetic approaches. These novel measurement solutions and their prospects to improve soil surface water content determination will be presented.

  19. Influence of soil moisture content on surface albedo and soil thermal parameters at a tropical station

    Science.gov (United States)

    Sugathan, Neena; Biju, V.; Renuka, G.

    2014-06-01

    Half hourly data of soil moisture content, soil temperature, solar irradiance, and reflectance are measured during April 2010 to March 2011 at a tropical station, viz., Astronomical Observatory, Thiruvananthapuram, Kerala, India (76°59'E longitude and 8°29'N latitude). The monthly, seasonal and seasonal mean diurnal variation of soil moisture content is analyzed in detail and is correlated with the rainfall measured at the same site during the period of study. The large variability in the soil moisture content is attributed to the rainfall during all the seasons and also to the evaporation/movement of water to deeper layers. The relationship of surface albedo on soil moisture content on different time scales are studied and the influence of solar elevation angle and cloud cover are also investigated. Surface albedo is found to fall exponentially with increase in soil moisture content. Soil thermal diffusivity and soil thermal conductivity are also estimated from the subsoil temperature profile. Log normal dependence of thermal diffusivity and power law dependence of thermal conductivity on soil moisture content are confirmed.

  20. Influence of soil moisture content on surface albedo and soil thermal parameters at a tropical station

    Indian Academy of Sciences (India)

    Neena Sugathan; V Biju; G Renuka

    2014-07-01

    Half hourly data of soil moisture content, soil temperature, solar irradiance, and reflectance are measured during April 2010 to March 2011 at a tropical station, viz., Astronomical Observatory, Thiruvananthapuram, Kerala, India (76° 59’E longitude and 8°29’N latitude). The monthly, seasonal and seasonal mean diurnal variation of soil moisture content is analyzed in detail and is correlated with the rainfall measured at the same site during the period of study. The large variability in the soil moisture content is attributed to the rainfall during all the seasons and also to the evaporation/movement of water to deeper layers. The relationship of surface albedo on soil moisture content on different time scales are studied and the influence of solar elevation angle and cloud cover are also investigated. Surface albedo is found to fall exponentially with increase in soil moisture content. Soil thermal diffusivity and soil thermal conductivity are also estimated from the subsoil temperature profile. Log normal dependence of thermal diffusivity and power law dependence of thermal conductivity on soil moisture content are confirmed.

  1. Photochemical behavior of benzo[a]pyrene on soil surfaces under UV light irradiation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-hong; LI Pei-jun; GONG Zong-qiang; Oni Adeola A.

    2006-01-01

    The rates of photodegradation and photocatalysis of benzo [a]pyrene (BaP) on soil surfaces under UV light have been studied. Different parameters such as temperature, soil particle sizes, and soil depth responsible for photodegradation, catalyst loads and wavelength of UV irradiation blamed for photocatalysis have been monitored. The results obtained indicated that BaP photodegradation follows pseudo-first-order kinetics. BaP photodegradation was the fastest at 30℃. The rates of BaP photodegradation at different soil particle size followed the order: less than 1 mm>less than 0.45 mm>less than 0.25 mm. When the soil depth increased from 1 mm to 4 mm, the half-life increased from 13.23 d to 17.73 d. The additions of TiO2 or Fe2O3 accelerated the photodegradation of BaP, and the photocatalysis of BaP follows pseudo-first-order kinetics. Changes in catalyst loads of TiO2 (0.5%,1%, 2%, and 3% (wt)) or Fe2O3 (2%, 5%, 7%, and 10% (wt)) did not significantly affect the degradation rates. Both BaP photocatalysis in the presence of TiO2 and Fe2O3 were the fastest at 254 nm UV irradiation.

  2. Restoring the natural state of the soil surface by biocrusts

    Science.gov (United States)

    Zaady, Eli; Ungar, Eugene D.; Stavi, Ilan; Shuker, Shimshon; Knoll, Yaakov M.

    2017-04-01

    In arid and semi-arid areas, with mean annual precipitation of 70-200 mm, the dominant component of the ground cover is biocrusts composed of cyanobacteria, moss and lichens. Biocrusts play a role in stabilizing the soil surface, which reduces erosion by water and wind. Human disturbances, such as heavy vehicular traffic, earthworks, overgrazing and land mining destroy the soil surface and promote erosion. The aim of the study was to evaluate restoration of the soil surface by the return of a biocrust layer. We examined the impact of disturbances on the creation of a stable crust and on the rate of recovery. Biocrust disturbance was studied in two sites in the northern Negev. The nine treatments included different rates of biocrust inoculum application and NPK fertilization. Recovery rates of the biocrusts were monitored for five years using chemical, physical and bio-physiological tests which determined infiltration rate, soil surface resistance to pressure, shear force of the soil surface, levels of chlorophyll, organic matter and polysaccharide, NDVI and aggregate stability. The results show that untreated disturbed biocrusts present long-term damage and a very slow rate of recovery, which may take decades, while most of the treatments showed a faster recovery. In particular, NDVI, polysaccharide levels and aggregate stability showed steady improvements over the research period.

  3. Effect of Electrolytes on Surface Charge Characteristics of Red Soils

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; HEQUN; 等

    1992-01-01

    The zero point of charge (ZPC) and the remaining charge σp at ZPC are two important parameters characterizing surface charge of red soils.Fourteen red soil samples of different soil type and parent material were treated with dithionite-citrate-dicarbonate (DCB) and Na2CO3 respectively.ZPC and σp of the samples in three indifferent electrolytes (NaCl,Na2SO4,and NaH2PO4) were determined.Kaolinite was used as reference.The results showed that ZPC of red soils was affected by the composition of parent materials and clay minerals and in significantly positive correlation with the content of total iron oxide (Fet),free iron oxide (Fed),amorphous iron oxide (Feo),aluminum oxide (Alo) and clay,but it was negatively correlated with the content of total silica (Sit).The σp of red soils was also markedly influenced by mineral components.Organic components were also contributing factor to the value of σp.The surface charges of red soils were evidently affected by the constitution of the electrolytes.Specific adsorption of anions in the electrolytes tended to make the ZPC of red soils shift to a higher pH value and to increase positive surface charges of the soils,thus leading to change of the σp value and decrease of the remaining net negative charges,even to the soils becoming net positive charge carriers.The effect of phosphate anion was greater than that of sulfate ion.

  4. Relationship Between Iron Oxides and Surface Charge Characteristics in Soils

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; WANGWEI-JUN

    1991-01-01

    The relationship between iron oxides and surface charge characteristics in variable charge soils (latosol and red earth) was studied in following three ways.(1)Remove free iron oxides (Fed) and amorphous iron oxides (Feo) from the soils with sodium dithionite and acid ammonium oxalate solution respectively.(2) Add 2% glucose (on the basis of air-dry soil weight) to soils and incubate under submerged condition to activate iron oxides,and then the mixtures are dehydrated and air-dried to age iron oxides.(3) Precipitate various crystalline forms of iron oxides onto kaolinite.The results showed that free iron oxides (Fed) were the chief carrier of variable positive charges.Of which crystalline iron oxides (Fed-Feo) presented mainly as discrete particles in the soils and could only play a role of the carrier of positive charges,and did little influence on negative charges.Whereas the amorphous iron oxides (Feo),which presented mainly fas a coating with a large specific surface area,not only had positive charges,but also blocked the negative charge sites in soils.Submerged incubation activated iron oxides in the soils,and increased the amount of amorphous iron oxides and the degree of activation of iron oxide,which resulted in the increase of positive and negative charges of soils.Dehydration and air-dry aged iron oxides in soils and decreased the amount of amorphous iron oxides and the degree of activation of iron oxide,and also led to the decrease of positive and negative charges.Both the submerged incubation and the dehydration and air-dry had no significant influence on net charges.Precipitation of iron oxides onto kaolinite markedly increased positive charges and decreased negative charges.Amorphous iron oxide having a larger surface area contributed more positive charge sites and blocked more negative charge sites in kaolinite than crystalline goethite.

  5. [Distribution of soil organic carbon in surface soil along a precipitation gradient in loess hilly area].

    Science.gov (United States)

    Sun, Long; Zhang, Guang-hui; Luan, Li-li; Li, Zhen-wei; Geng, Ren

    2016-02-01

    Along the 368-591 mm precipitation gradient, 7 survey sites, i.e. a total 63 investigated plots were selected. At each sites, woodland, grassland, and cropland with similar restoration age were selected to investigate soil organic carbon distribution in surface soil (0-30 cm), and the influence of factors, e.g. climate, soil depth, and land uses, on soil organic carbon distribution were analyzed. The result showed that, along the precipitation gradient, the grassland (8.70 g . kg-1) > woodland (7.88 g . kg-1) > farmland (7.73 g . kg-1) in concentration and the grassland (20.28 kg . m-2) > farmland (19.34 kg . m-2) > woodland (17.14 kg . m-2) in density. The differences of soil organic carbon concentration of three land uses were not significant. Further analysis of pooled data of three land uses showed that the surface soil organic carbon concentration differed significantly at different precipitation levels (Psoil organic carbon concentration (r=0.838, Psoil organic carbon increased with annual precipitation 0. 04 g . kg-1 . mm-1, density 0.08 kg . m-2 . mm-1. The soil organic carbon distribution was predicted with mean annual precipitation, soil clay content, plant litter in woodland, and root density in farmland.

  6. Microscope Image of a Martian Soil Surface Sample

    Science.gov (United States)

    2008-01-01

    This is the closest view of the material underneath NASA's Phoenix Mars Lander. This sample was taken from the top centimeter of the Martian soil, and this image from the lander's Optical Microscope demonstrates its overall composition. The soil is mostly composed of fine orange particles, and also contains larger grains, about a tenth of a millimeter in diameter, and of various colors. The soil is sticky, keeping together as a slab of material on the supporting substrate even though the substrate is tilted to the vertical. The fine orange grains are at or below the resolution of the Optical Microscope. Mixed into the soil is a small amount&mdashabout 0.5 percent&mdashof white grains, possibly of a salt. The larger grains range from black to almost transparent in appearance. At the bottom of the image, the shadows of the Atomic Force Microscope (AFM) beams are visible. This image is 1 millimeter x 2 millimeters. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by JPL, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

  7. VTORTHO_0_5M_PAN_2000

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_2000 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  8. VTORTHO_0_5M_PAN_2009

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_2009 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  9. VTORTHO_0_5M_PAN_1999

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_1999 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  10. VTORTHO_0_5M_PAN_1995

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_1995 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  11. VTORTHO_0_5M_PAN_2007

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_2007 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  12. 2009 - Black & White - Essex (0.5m)

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTORTHO_0_5M_PAN_2009 data includes panchromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution)....

  13. VTORTHO_0_5M_PAN_2011

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_CLR_2011 data includes truecolor and color infrared (4 band) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery...

  14. VTORTHO_0_5M_CLRIR_2011

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_2011 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  15. VTORTHO_0_5M_PAN_2006

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_2006 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  16. VTORTHO_0_5M_PAN_1996

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_1996 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  17. VTORTHO_0_5M_PAN_2008

    Data.gov (United States)

    Vermont Center for Geographic Information — The VTORTHO_0_5M_PAN_2008 data includes pancromatic (black and white) orthophotography (orthophoto) at 1:5000 scale (0.5 meter cell resolution). The imagery was...

  18. Soil fertility in deserts: a review on the influence of biological soil crusts and the effect of soil surface disturbance on nutrient inputs and losses

    Science.gov (United States)

    Reynolds, R.; Phillips, S.; Duniway, M.; Belnap, J.

    2003-01-01

    Sources of desert soil fertility include parent material weathering, aeolian deposition, and on-site C and N biotic fixation. While parent materials provide many soil nutrients, aeolian deposition can provide up to 75% of plant-essential nutrients including N, P, K, Mg, Na, Mn, Cu, and Fe. Soil surface biota are often sticky, and help retain wind-deposited nutrients, as well as providing much of the N inputs. Carbon inputs are from both plants and soil surface biota. Most desert soils are protected by cyanobacterial-lichen-moss soil crusts, chemical crusts and/or desert pavement. Experimental disturbances applied in US deserts show disruption of soil surfaces result in decreased N and C inputs from soil biota by up to 100%. The ability to glue aeolian deposits in place is compromised, and underlying soils are exposed to erosion. The ability to withstand wind increases with biological and physical soil crust development. While most undisturbed sites show little sediment production, disturbance by vehicles or livestock produce up to 36 times more sediment production, with soil movement initiated at wind velocities well below commonly-occurring wind speeds. Soil fines and flora are often concentrated in the top 3 mm of the soil surface. Winds across disturbed areas can quickly remove this material from the soil surface, thereby potentially removing much of current and future soil fertility. Thus, disturbances of desert soil surfaces can both reduce fertility inputs and accelerate fertility losses.

  19. Denitrification 'hot spots' in soil following surface residue application

    Science.gov (United States)

    Kuntz, Marianne; Morley, Nicholas J.; Hallett, Paul D.; Watson, Christine; Baggs, Elizabeth M.

    2015-04-01

    The availability of organic C is an important driver for the production and reduction of the greenhouse gas nitrous oxide (N2O) during denitrification. Denitrification as a response to plant residue amendments to soil surfaces has been extensively researched. However, the nature of hotspot sites of N2O production and reduction within the soil profile, especially in relation to the location of applied residues, is unknown. In a laboratory experiment we investigated the relationship between denitrifier N2O surface fluxes and N2O production and reduction sites. Probes which equilibrate with the soil gas phase by diffusion were developed to quantify denitrification products and product ratios at 1-2 cm, 4.5-5.5 cm or 8-9 cm from the surface. 13C labelled barley straw was incorporated at rates of 0, 2 and 4 t ha-1 into the top 3 cm of soil and subsequently amended with 14NH415NO3. In a three week experiment the soil gas phase at the three depths was analysed for 15N-N2O, 15N-N2, 13C-CO2 and O2 concentrations. Additionally, cores were destructively sampled for mineral 15N as well as microbial C and dissolved C in the respective depths. 15N-N2O and CO2 surface fluxes peaked one day after N application, with residue application resulting in significantly higher 15N-N2O emission rates compared to the non-amended control. The timing of the 15N-N2O surface flux on day 1 was related to maximum 15N-N2O concentrations of 36.6 μg 15N L-1 within the pore space at 5 cm depth. Three days after fertilizer application 15N-N2O pore space concentrations had significantly increased to 193 μg 15N L-1 at 9 cm depth indicating denitrifier activity at greater depth. Denitrification below the soil surface could be explained by increased microbial activity, oxygen depletion with increasing depth and progressive downwards diffusion of fertilizer NO3-. However, C availability appeared to only affect denitrification in the surface layer in which the residue was incorporated. Our results provide

  20. Near surface soil vapor clusters for monitoring emissions of volatile organic compounds from soils.

    Science.gov (United States)

    Ergas, S J; Hinlein, E S; Reyes, P O; Ostendorf, D W; Tehrany, J P

    2000-01-01

    The overall objective of this research was to develop and test a method of determining emission rates of volatile organic compounds (VOCs) and other gases from soil surfaces. Soil vapor clusters (SVCs) were designed as a low dead volume, robust sampling system to obtain vertically resolved profiles of soil gas contaminant concentrations in the near surface zone. The concentration profiles, when combined with a mathematical model of porous media mass transport, were used to calculate the contaminant flux from the soil surface. Initial experiments were conducted using a mesoscale soil remediation system under a range of experimental conditions. Helium was used as a tracer and trichloroethene was used as a model VOC. Flux estimations using the SVCs were within 25% of independent surface flux estimates and were comparable to measurements made using a surface isolation flux chamber (SIFC). In addition, method detection limits for the SVC were an order of magnitude lower than detection limits with the SIFC. Field trials, conducted with the SVCs at a bioventing site, indicated that the SVC method could be easily used in the field to estimate fugitive VOC emission rates. Major advantages of the SVC method were its low detection limits, lack of required auxiliary equipment, and ability to obtain real-time estimates of fugitive VOC emission rates.

  1. Enhancement of chromate reduction in soils by surface modified biochar.

    Science.gov (United States)

    Mandal, Sanchita; Sarkar, Binoy; Bolan, Nanthi; Ok, Yong Sik; Naidu, Ravi

    2017-01-15

    Chromium (Cr) is one of the common metals present in the soils and may have an extremely deleterious environmental impact depending on its redox state. Among two common forms, trivalent Cr(III) is less toxic than hexavalent Cr(VI) in soils. Carbon (C) based materials including biochar could be used to alleviate Cr toxicity through converting Cr(VI) to Cr(III). Incubation experiments were conducted to examine Cr(VI) reduction in different soils (Soil 1: pH 7.5 and Soil 2: pH 5.5) with three manures from poultry (PM), cow (CM) and sheep (SM), three respective manure-derived biochars (PM biochar (PM-BC), CM biochar (CM-BC) and SM biochar (SM-BC)) and two modified biochars (modified PM-BC (PM-BC-M) and modified SM-BC (SM-BC-M)). Modified biochar was synthesized by incorporating chitosan and zerovalent iron (ZVI) during pyrolysis. Among biochars, highest Cr(VI) reduction was observed with PM-BC application (5%; w/w) (up to 88.12 mg kg(-1); 45% reduction) in Soil 2 (pH 5.5). The modified biochars enhanced Cr(VI) reduction by 55% (SM-BC-M) compared to manure (29%, SM) and manure-derived biochars (40% reduction, SM-BC). Among the modified biochars, SM-BC-M showed a higher Cr(VI) reduction rate (55%) than PM-BC-M (48%) in Soil 2. Various oxygen-containing surface functional groups such as phenolic, carboxyl, carbonyl, etc. on biochar surface might act as a proton donor for Cr(VI) reduction and subsequent Cr(III) adsorption. This study underpins the immense potential of modified biochar in remediation of Cr(VI) contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Soil surface sealing reverse or promote desertification?

    Science.gov (United States)

    Assouline, Shmuel; Thompson, Sally; Chen, Li; Svoray, Tal; Sela, Shai; Katul, Gabriel

    2016-04-01

    Vegetation cover in dry regions is a key variable determining desertification. Bare soils exposed to rainfall by desertification can form physical crusts that reduce infiltration, exacerbating water stress on the remaining vegetation. Paradoxically, field studies show that crust removal is associated with plant mortality in desert systems, while artificial biological crusts can improve plant regeneration. Here, it is shown how physical crusts can act as either drivers of, or buffers against desertification depending on their environmental context. The behavior of crusts is first explored using a simplified theory for water movement on a uniform, partly vegetated slope subject to stationary hydrologic conditions. Numerical model runs supplemented with field data from a semiarid Long-Term Ecological Research (LTER) site are then applied to represent more realistic environmental conditions. When vegetation cover is significant, crusts can drive desertification, but this process is potentially self-limiting. For low vegetation cover, crusts mitigate against desertification by providing water subsidy to plant communities through a runoff-runon mechanism.

  3. Ni-doped La0.5Sr0.5TiO3 nanofibers: Fabrication and intrinsic ferromagnetism

    Science.gov (United States)

    Ponhan, Wichaid; Amornkitbamrung, Vittaya; Maensiri, Santi

    2016-06-01

    We report room-temperature ferromagnetism in ˜104-133 nm nanofibers of La0.5Sr0.5Ti1- x Ni x O3 (0.02 ≤ x ≤ 0.05). As-spun nanofibers of La0.5Sr0.5Ti1- x Ni x O3 are fabricated by an electrospinning technique. Nanofibers of the as spun and calcined La0.5Sr0.5Ti1- x Ni x O3 samples are characterized using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS), X-ray absorption near edge structure (XANES) determination, and vibrating sample magnetometry (VSM). The results of XRD analysis and TEM together with selected electron diffraction (SEAD) analysis indicate that La0.5Sr0.5Ti1- x Ni x O3 nanofibers have a cubic perovskite structure with no secondary phase. The as-spun samples are paramagnetic, whereas the La0.5Sr0.5Ti1- x Ni x O3 samples are ferromagnetic having specific magnetizations of 0.098-0.484 emu/g at 10 kOe. The XPS spectra show that there are some oxygen vacancies in the nanofibers, which its may play an important role in inducing room-temperature ferromagnetism in La0.5Sr0.5Ti1- x Ni x O3 nanofibers. XANES spectra show that most of the Ni ions in La0.5Sr0.5Ti1- x Ni x O3 nanofibers are in the Ni2+ state mixed with some Ni metal. The finding of room temperature ferromagnetism in this nanofibrous structure of the La0.5Sr0.5Ti1- x Ni x O3 system is of interest in research on diluted magnetic oxides.

  4. Selective Etching of Silicon in Preference to Germanium and Si0.5Ge0.5.

    Science.gov (United States)

    Ahles, Christopher F; Choi, Jong Youn; Wolf, Steven; Kummel, Andrew C

    2017-06-21

    The selective etching characteristics of silicon, germanium, and Si0.5Ge0.5 subjected to a downstream H2/CF4/Ar plasma have been studied using a pair of in situ quartz crystal microbalances (QCMs) and X-ray photoelectron spectroscopy (XPS). At 50 °C and 760 mTorr, Si can be etched in preference to Ge and Si0.5Ge0.5, with an essentially infinite Si/Ge etch-rate ratio (ERR), whereas for Si/Si0.5Ge0.5, the ERR is infinite at 22 °C and 760 mTorr. XPS data showed that the selectivity is due to the differential suppression of etching by a ∼2 ML thick CxHyFz layer formed by the H2/CF4/Ar plasma on Si, Ge, and Si0.5Ge0.5. The data are consistent with the less exothermic reaction of fluorine radicals with Ge or Si0.5Ge0.5 being strongly suppressed by the CxHyFz layer, whereas, on Si, the CxHyFz layer is not sufficient to completely suppress etching. Replacing H2 with D2 in the feed gas resulted in an inverse kinetic isotope effect (IKIE) where the Si and Si0.5Ge0.5 etch rates were increased by ∼30 times with retention of significant etch selectivity. The use of D2/CF4/Ar instead of H2/CF4/Ar resulted in less total carbon deposition on Si and Si0.5Ge0.5 and gave less Ge enrichment of Si0.5Ge0.5. These results are consistent with the selectivity being due to the differential suppression of etching by an angstrom-scale carbon layer.

  5. Vanadium Trineodecanoate Promoter for Fiberglass-Polyester Soil Surfacings.

    Science.gov (United States)

    1980-06-01

    surfaces for soils consists of a polyester resin, cumene hydroperoxide catalyst and a promoter solution containing a vanadium salt and N,N-dimethyl-p-tolui...4 Synthesis of Vanadium Trineodecanoate .. .... ......... 4 Reactions Using Various Reagents. ..... ........... 4 Analysis of Vanadium...polymer system consists of a polyester resin, a peroxide cata- lyst ( cumene hydroperoxide) and a two-part, premixed, promoter solution. The promoter

  6. Photodegradation of pesticides on plant and soil surfaces.

    Science.gov (United States)

    Katagi, Toshiyuki

    2004-01-01

    importance of an emission spectrum of the light source near its surface was clarified. Most photochemical information comes from photolysis in organic solvents or on glass surfaces and/or plant metabolism studies. Epicuticular waxes may be approximated by long-chain hydrocarbons as a very viscous liquid or solid, but the existing form of pesticide molecules in waxes is still obscure. Either coexistence of formulation agents or steric constraint in the rigid medium would cause a change of molecular excitation, deactivation, and photodegradation mechanisms, which should be further investigated to understand the dissipation profiles of a pesticide in or on crops in the field. A thin-layer system with a coat of epicuticular waxes extracted from leaves or isolated cuticles has been utilized as a model, but its application has been very limited. There appear to be gaps in our knowledge about the surface chemistry and photochemistry of pesticides in both rigid media and plant metabolism. Photodegradation studies, for example, by using these models to eliminate contribution from metabolic conversion as much as possible, should be extensively conducted in conjunction with wax chemistry, with the controlling factors being clarified. As with soil surfaces, the effects of atmospheric oxidants should also be investigated. Based on this knowledge, new methods of kinetic analysis or a device simulating the fate of pesticides on these surfaces could be more rationally developed. Concerning soil photolysis, detailed mechanistic analysis of the mobility and fate of pesticides together with volatilization from soil surfaces has been initiated and its spatial distribution with time has been simulated with reasonable precision on a laboratory scale. Although mechanistic analyses have been conducted on penetration of pesticides through cuticular waxes, its combination with photodegradation to simulate the real environment is awaiting further investigation.

  7. Degradation and Sorption of Imidacloprid in Dissimilar Surface and Subsurface Soils

    Science.gov (United States)

    Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. Once pesticides move past the surface soil layers, subsurface soil physical, chemical, and biological properties significantly affect pesticide fate and the potential for groundwater contam...

  8. Room temperature hole-burning of X-ray induced Sm(2+) in nanocrystalline Ba0.5Sr0.5FCl0.5Br0.5:Sm(3+) prepared by mechanochemistry.

    Science.gov (United States)

    Wang, Xianglei; Riesen, Hans; Stevens-Kalceff, Marion A; Rajan, Rajitha Papakutty

    2014-10-09

    Alloyed nanocrystalline Ba0.5Sr0.5FCl0.5Br0.5 doped with Sm(3+) ions was prepared by a facile ball milling method at room temperature. Spectral hole-burning properties of Sm(2+) ions from X-irradiated sample were investigated in the (7)F0-(5)D0 transition between 2.5 K and room temperature. The alloying allows a "chemical" broadening of the inhomogeneous width of the (7)F0-(5)D0 f-f transition to 40 cm(-1); spectral holes with a homogeneous width of 5 cm(-1) can be burnt, yielding a figure-of-merit of Γinh/Γhom = 8. Mechanochemical preparation methods have a significant potential for the preparation of functional materials for applications in frequency domain optical data storage and as X-ray storage phosphors by allowing the preparation of tailored solid solutions.

  9. Physically plausible prescription of land surface model soil moisture

    Science.gov (United States)

    Hauser, Mathias; Orth, René; Thiery, Wim; Seneviratne, Sonia

    2016-04-01

    Land surface hydrology is an important control of surface weather and climate, especially under extreme dry or wet conditions where it can amplify heat waves or floods, respectively. Prescribing soil moisture in land surface models is a valuable technique to investigate this link between hydrology and climate. It has been used for example to assess the influence of soil moisture on temperature variability, mean and extremes (Seneviratne et al. 2006, 2013, Lorenz et al., 2015). However, perturbing the soil moisture content artificially can lead to a violation of the energy and water balances. Here we present a new method for prescribing soil moisture which ensures water and energy balance closure by using only water from runoff and a reservoir term. If water is available, the method prevents soil moisture decrease below climatological values. Results from simulations with the Community Land Model (CLM) indicate that our new method allows to avoid soil moisture deficits in many regions of the world. We show the influence of the irrigation-supported soil moisture content on mean and extreme temperatures and contrast our findings with that of earlier studies. Additionally, we will assess how long into the 21st century the new method will be able to maintain present-day climatological soil moisture levels for different regions. Lorenz, R., Argüeso, D., Donat, M.G., Pitman, A.J., den Hurk, B.V., Berg, A., Lawrence, D.M., Chéruy, F., Ducharne, A., Hagemann, S. and Meier, A., 2015. Influence of land-atmosphere feedbacks on temperature and precipitation extremes in the GLACE-CMIP5 ensemble. Journal of Geophysical Research: Atmospheres. Seneviratne, S.I., Lüthi, D., Litschi, M. and Schär, C., 2006. Land-atmosphere coupling and climate change in Europe. Nature, 443(7108), pp.205-209. Seneviratne, S.I., Wilhelm, M., Stanelle, T., Hurk, B., Hagemann, S., Berg, A., Cheruy, F., Higgins, M.E., Meier, A., Brovkin, V. and Claussen, M., 2013. Impact of soil moisture

  10. Dark-red-emitting CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots: Effect of chemicals on properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ping, E-mail: mse_yangp@ujn.edu.cn; Zhang, Aiyu; Li, Xiaoyu; Liu, Ning; Zhang, Yulan; Zhang, Ruili

    2013-08-15

    CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. - Graphical abstract: CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots (QDs) with tunable photoluminescence, high PL efficiency, and high stability through organic synthesis, in which chemicals affected the properties of the QDs. Display Omitted - Highlights: • CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots created via organic synthesis. • Chemicals affected the properties of the quantum dots. • The quantum dots revealed high photoluminescence efficiency and stability. • The quantum dots with tunable photoluminescence in a range from yellow to dark red. • The QDs are utilizable for various applications such as biological labeling.

  11. Computer Implementation of the Bounding Surface Plasticity Model for Cohesive Soils.

    Science.gov (United States)

    1983-12-01

    23 REFERENCES 1. Dafalias, Y.F., and L.R. Herrmann, "A Bounding Surface Soil Plasticity Model", Proceedings of the International Symposium of Soils...Herrmann, "Bounding Surface Formulatin of Soil Plasticity ", Chapter in Soil Mechanics - Transient and Cyclic Loads, John Wiley and Sons, Eds. O.C...Herrmann and Y.F. r)afalias, "User’s Manual for MODCAL-Bounding Surface Soil Plasticity Model Calibration and Prediction Code (Volume I)," Civil

  12. A Study of the Relations between Soil Moisture, Soil Temperatures and Surface Temperatures Using ARM Observations and Offline CLM4 Simulations

    Directory of Open Access Journals (Sweden)

    Menglin S. Jin

    2014-09-01

    Full Text Available Soil temperature, soil moisture, skin temperature and 2-m air temperature are examined from both ground observations and the offline community land model (CLM4. Two-layer soil moisture and three-layer soil temperature observations from six-year (2003–2008 ground measurements at the Lamont, Oklahoma site supported by the Atmospheric Radiation Measurement (ARM Program of the Department of Energy (DOE show clear vertical and temporal relations between soil temperature and soil moisture with surface skin temperature and 2-m air temperature. First, daily means reveal that all of these variables have clear seasonal variations, with temperatures peaking in summer and minimizing in winter as a result of surface insolation. Nevertheless, the 2-m air temperature and upper soil temperature (−0.05 m peak at 2 h after that of surface skin temperature because of the lag of transport of heat from the skin level to the 2-m air and to underground respectively. As a result of such lag, at the monthly annual cycle scale, 2-m air temperature has higher correlation with upper soil temperature than skin temperature does. Second, there are little diurnal and annual variations at the lowest soil layer (−0.25 m. Third, a negative correlation (~−0.40 between skin temperature and soil moisture is observed, consistent with the expectation that heat flux and evaporation are competing physical processes for redistributing surface net radiation. Soil moisture, however, minimizes in March and maximizes in winter due to the local rainfall cycle. All of these key observed relations are qualitatively reproduced in the offline CLM4 using the atmosphere forcing derived from ARM observations. Nevertheless, CLM4 is too dry at the upper layer and has less variation at the lower layer than observed. In addition, CLM4 shows stronger correlation between Tsoil and Tskin (r = 0.96 than the observations (r = 0.64, while the predicted nighttime Tskin is 0.5–2 °C higher than the

  13. Carbon black retention in saturated natural soils: Effects of flow conditions, soil surface roughness and soil organic matter.

    Science.gov (United States)

    Lohwacharin, J; Takizawa, S; Punyapalakul, P

    2015-10-01

    We evaluated factors affecting the transport, retention, and re-entrainment of carbon black nanoparticles (nCBs) in two saturated natural soils under different flow conditions and input concentrations using the two-site transport model and Kelvin probe force microscopy (KPFM). Soil organic matter (SOM) was found to create unfavorable conditions for the retention. Despite an increased flow velocity, the relative stability of the estimated maximum retention capacity in soils may suggest that flow-induced shear stress forces were insufficient to detach nCB. The KPFM observation revealed that nCBs were retained at the grain boundary and on surface roughness, which brought about substantial discrepancy between theoretically-derived attachment efficiency factors and the ones obtained by the experiments using the two-site transport model. Thus, decreasing ionic strength and increasing solution pH caused re-entrainment of only a small fraction of retained nCB in the soil columns.

  14. Fourier and granulometry methods on 3D images of soil surfaces for evaluating soil aggregate size distribution

    DEFF Research Database (Denmark)

    Jensen, T.; Green, O.; Munkholm, Lars Juhl;

    2016-01-01

    The goal of this research is to present and compare two methods for evaluating soil aggregate size distribution based on high resolution 3D images of the soil surface. The methods for analyzing the images are discrete Fourier transform and granulometry. The results of these methods correlate...... with a measured weight distribution of the soil aggregates. The results have shown that it is possible to distinguish between the cultivated and the uncultivated soil surface. A sensor system suitable for capturing in-situ high resolution 3D images of the soil surface is also described. This sensor system...... is based on a SICK LMS111 laser range scanner....

  15. Shear strain in Nd0.5Ca0.5MnO3 at high pressures.

    Science.gov (United States)

    Arulraj, Anthony; Dinnebier, Robert E; Carlson, Stefan; Hanfland, Michael; van Smaalen, Sander

    2005-04-29

    High-pressure x-ray powder diffraction has been measured on the half doped rare earth manganite Nd0.5Ca0.5MnO3 up to a pressure of 15 GPa. We report the presence of a quantifiable amount of shear distortion of the MnO6 octahedra in Nd0.5Ca0.5MnO3 at high pressures. The lattice strain of Nd0.5Ca0.5MnO3 is minimal at a crossover pressure of p* approximately 7 GPa, with the same lattice strain above and below this pressure achieved by shear and Jahn-Teller-type distortions, respectively. The increase in shear strain with increasing pressure provides a mechanism for the insulating behavior of manganites at high pressures that has not been considered before.

  16. Topochemical reduction of the Ruddlesden-Popper phases Sr2Fe(0.5)Ru(0.5)O4 and Sr3(Fe(0.5)Ru(0.5))2O7.

    Science.gov (United States)

    Denis Romero, Fabio; Gianolio, Diego; Cibin, Giannantonio; Bingham, Paul A; d'Hollander, Jeanne-Clotilde; Forder, Susan D; Hayward, Michael A

    2013-10-01

    Reaction of the Ruddlesden-Popper phases Sr2Fe(0.5)Ru(0.5)O4 and Sr3(Fe(0.5)Ru(0.5))2O7 with CaH2 results in the topochemical deintercalation of oxide ions from these materials and the formation of samples with average compositions of Sr2Fe(0.5)Ru(0.5)O(3.35) and Sr3(Fe(0.5)Ru(0.5))2O(5.68), respectively. Diffraction data reveal that both the n = 1 and n = 2 samples consist of two-phase mixtures of reduced phases with subtly different oxygen contents. The separation of samples into two phases upon reduction is discussed on the basis of a short-range inhomogeneous distribution of iron and ruthenium in the starting materials. X-ray absorption data and Mössbauer spectra reveal the reduced samples contain an Fe(3+) and Ru(2+/3+) oxidation state combination, which is unexpected considering the Fe(3+)/Fe(2+) and Ru(3+)/Ru(2+) redox potentials, suggesting that the local coordination geometry of the transition metal sites helps to stabilize the Ru(2+) centers. Fitted Mössbauer spectra of both the n = 1 and n = 2 samples are consistent with the presence of Fe(3+) cations in square planar coordination sites. Magnetization data of both materials are consistent with spin glass-like behavior.

  17. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.

    1988-12-01

    Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs.

  18. Structural stability, electronic, magnetic and optical properties of zincblende Zn0.5V0.5Te under pressure

    Science.gov (United States)

    Yin, Zhu-Hua; Zhang, Jian-Min

    2016-10-01

    The structural stability, electronic, magnetic and optical properties of zincblende Zn0.5V0.5Te under pressures 0-5 GPa are investigated by the spin-polarized first-principles calculation. Under pressure, the Zn0.5V0.5Te is always half-metal with the total magnetic moment μtot of 3μB / cell mainly contributed by V2+ ion, but the spin-down channel opens a band gap. The Zn0.5V0.5Te also behaves in a ductile manner and is mechanical stable until 3.78 GPa pressure. The static dielectric function ε1 (0) and refractive index n (0) increase with pressure. The two absorption peaks located in energy regions 0-20 eV and 35-50 eV not only increase but also shift to the higher energy region (blue shift) with pressure. So the electronic and optical properties of Zn0.5V0.5Te could be tuned through external pressure, which is beneficial to the electronic and optical applications.

  19. Estimating the Soil Moisture Profile by Assimilating Near-Surface Observations with the Ensemble Kalman Filter (EnKF)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The paper investigates the ability to retrieve the true soil moisture profile by assimilating near-surface soil moisture into a soil moisture model with an ensemble Kalman filter (EnKF) assimilation scheme,including the effect of ensemble size, update interval and nonlinearities in the profile retrieval, the required time for full retrieval of the soil moisture profiles, and the possible influence of the depth of the soil moisture observation. These questions are addressed by a desktop study using synthetic data. The "true"soil moisture profiles are generated from the soil moisture model under the boundary condition of 0.5 cm d-1 evaporation. To test the assimilation schemes, the model is initialized with a poor initial guess of the soil moisture profile, and different ensemble sizes are tested showing that an ensemble of 40 members is enough to represent the covariance of the model forecasts. Also compared are the results with those from the direct insertion assimilation scheme, showing that the EnKF is superior to the direct insertion assimilation scheme, for hourly observations, with retrieval of the soil moisture profile being achieved in 16 h as compared to 12 days or more. For daily observations, the true soil moisture profile is achieved in about 15 days with the EnKF, but it is impossible to approximate the true moisture within 18 days by using direct insertion. It is also found that observation depth does not have a significant effect on profile retrieval time for the EnKF. The nonlinearities have some negative influence on the optimal estimates of soil moisture profile but not very seriously.

  20. Shallow Subsurface Soil Moisture Dynamics in the Root-Zone and Bulk Soil of Sparsely Vegetated Land Surfaces as Impacted by Near-Surface Atmospheric State

    Science.gov (United States)

    Trautz, A.; Illangasekare, T. H.; Tilton, N.

    2015-12-01

    Soil moisture is a fundamental state variable that provides the water necessary for plant growth and evapotranspiration. Soil moisture has been extensively studied in the context of bare surface soils and root zones. Less attention has focused on the effects of sparse vegetation distributions, such as those typical of agricultural cropland and other natural surface environments, on soil moisture dynamics. The current study explores root zone, bulk soil, and near-surface atmosphere interactions in terms of soil moisture under different distributions of sparse vegetation using multi-scale laboratory experimentation and numerical simulation. This research is driven by the need to advance our fundamental understanding of soil moisture dynamics in the context of improving water conservation and next generation heat and mass transfer numerical models. Experimentation is performed in a two-dimensional 7.3 m long intermediate scale soil tank interfaced with a climate-controlled wind tunnel, both of which are outfitted with current sensor technologies for measuring atmospheric and soil variables. The soil tank is packed so that a sparsely vegetated soil is surrounded by bulk bare soil; the two regions are separated by porous membranes to isolate the root zone from the bulk soil. Results show that in the absence of vegetation, evaporation rates vary along the soil tank in response to longitudinal changes in humidity; soil dries fastest upstream where evaporation rates are highest. In the presence of vegetation, soil moisture in the bulk soil closest to a vegetated region decreases more rapidly than the bulk soil farther away. Evapotranspiration rates in this region are also higher than the bulk soil region. This study is the first step towards the development of more generalized models that account for non-uniformly distributed vegetation and land surfaces exhibiting micro-topology.

  1. Effect of sintering temperature on micro structural and impedance spectroscopic properties of Ni0.5Zn0.5Fe2O4 nano ferrite

    Science.gov (United States)

    Venkatesh, Davuluri; Ramesh, K. V.; Sastry, C. V. S. S.

    2017-07-01

    Ni-Zn nanoferrite Ni0.5Zn0.5Fe2O4 is prepared by citrate gel auto combustion method and sintered at various temperatures 800, 900, 1000, 1100 and 1200°C. The room temperature x-ray diffraction conforms that the single phase spinel structure is formed. Crystallite size and density were increased with increasing of sintering temperature. From Raman spectroscopy all sintered samples are single phase with cubic spinel structure belong to Fd3m space group. From surface morphology studies it is clearly observed that the particle size increased with increasing of sintering temperature. Impedance spectroscopy revel that increasing of conductivity is due to grain resistance is decreased with increasing of sintering temperature. Cole-Cole plots are studied from impedance data. The electrical modulus analysis shows that non-Debye nature of Ni0.5Zn0.5Fe2O4 ferrite.

  2. Predicting climate change effects on surface soil organic carbon of Louisiana, USA.

    Science.gov (United States)

    Zhong, Biao; Xu, Yi Jun

    2014-10-01

    This study aimed to assess the degree of potential temperature and precipitation change as predicted by the HadCM3 (Hadley Centre Coupled Model, version 3) climate model for Louisiana, and to investigate the effects of potential climate change on surface soil organic carbon (SOC) across Louisiana using the Rothamsted Carbon Model (RothC) and GIS techniques at the watershed scale. Climate data sets at a grid cell of 0.5° × 0.5° for the entire state of Louisiana were collected from the HadCM3 model output for three climate change scenarios: B2, A2, and A1F1, that represent low, higher, and even higher greenhouse gas emissions, respectively. Geo-referenced datasets including USDA-NRCS Soil Geographic Database (STATSGO), USGS Land Cover Dataset (NLCD), and the Louisiana watershed boundary data were gathered for SOC calculation at the watershed scale. A soil carbon turnover model, RothC, was used to simulate monthly changes in SOC from 2001 to 2100 under the projected temperature and precipitation changes. The simulated SOC changes in 253 watersheds from three time periods, 2001-2010, 2041-2050, and 2091-2100, were tested for the influence of the land covers and emissions scenarios using SAS PROC GLIMMIX and PDMIX800 macro to separate Tukey-Kramer (p change from 30.7 t/ha in 2001 to 25.4, 26.6, and 27.0 t/ha in 2100, respectively. Annual SOC changes will be significantly different among the land cover classes including evergreen forest, mixed forest, deciduous forest, small grains, row crops, and pasture/hay (p < 0.0001), emissions scenarios (p < 0.0001), and their interactions (p < 0.0001).

  3. Piezoelectric non-linearity in PbSc0.5Ta0.5O3 thin films

    NARCIS (Netherlands)

    Chopra, A.; Kim, Y.; Alexe, M.; Hesse, D.

    2014-01-01

    Epitaxial (001)-oriented PbSc0.5Ta0.5O3 (PST) thin films were deposited by pulsed laser deposition. Local piezoelectric investigations performed by piezoelectric force microscopy show a dual slope for the piezoelectric coefficient. A piezoelectric coefficient of 3 pm/V was observed at voltages up to

  4. Cu-induced localization in the Fe-based superconductor FeTe0.5Se0.5

    Science.gov (United States)

    Wen, Jinsheng; Xu, Zhijun; Zhang, Cheng; Matsuda, Masa; Sobolev, Oleg; Park, Jitae; Bourret, Edith; Lee, Dunghai; Li, Qiang; Gu, Genda; Xu, Guangyong; Tranquada, John; Birgeneau, Robert

    2013-03-01

    We report neutron scattering and resistivity results on the Cu-substitution effects in FeTe0.5Se0.5 with a Tc of ~15 K. With a 2 % Cu substitution, the Tc is reduced to 8 K, and for Fe0.9Cu0.1Te0.5Se0.5, it is not superconducting. In Fe0.9Cu0.1Te0.5Se0.5, the low-energy magnetic excitations around the in-plane wave vector (0.5, 0.5) is greatly enhanced. Upon heating, the magnetic scattering is weakened, which is different from the temperature dependences of the Cu-free and 2 % Cu-doped sample. The spectral weight reduction upon warming decreases with increasing energy in the 10 % Cu-doped sample. We take these as evidences that Cu drives the system towards localization, which is confirmed by our resistivity data. These observations probably explain why superconductivity is absent in the Cu-doped BaFe2As2 system and demonstrate the inadequacy of the rigid-band shift model on the substitution effects of the 3 d transition metals. The work is supported by the U.S. Department of Energy.

  5. Actual evaporation estimation from infrared measurement of soil surface temperature

    Directory of Open Access Journals (Sweden)

    Davide Pognant

    2013-09-01

    Full Text Available Within the hydrological cycle, actual evaporation represents the second most important process in terms of volumes of water transported, second only to the precipitation phenomena. Several methods for the estimation of the Ea were proposed by researchers in scientific literature, but the estimation of the Ea from potential evapotranspiration often requires the knowledge of hard-to-find parameters (e.g.: vegetation morphology, vegetation cover, interception of rainfall by the canopy, evaporation from the canopy surface and uptake of water by plant roots and many existing database are characterized by missing or incomplete information that leads to a rough estimation of the actual evaporation amount. Starting from the above considerations, the aim of this study is to develop and validate a method for the estimation of the Ea based on two steps: i the potential evaporation estimation by using the meteorological data (i.e. Penman-Monteith; ii application of a correction factor based on the infrared soil surface temperature measurements. The dataset used in this study were collected during two measurement campaigns conducted both in a plain testing site (Grugliasco, Italy, and in a mountain South-East facing slope (Cogne, Italy. During those periods, hourly measurement of air temperature, wind speed, infrared surface temperature, soil heat flux, and soil water content were collected. Results from the dataset collected in the two testing sites show a good agreement between the proposed method and reference methods used for the Ea estimation.

  6. Fabrication and magnetic properties of Ni_(0.5)Zn_(0.5)Fe_2O_4 nanofibres by electrospinning

    Institute of Scientific and Technical Information of China (English)

    Xiang Jun; Shen Xiang-Qian; Song Fu-Zhan; Liu Ming-Quan

    2009-01-01

    NiZn ferrite/polyvinylpyrrolidone composite fibres were prepared by sol-gel assisted electrospinning. Ni_(0.5)Zn_(0.5)Fe_2O_4 nanofibres with a pure cubic spinel structure were obtained subsequently by calcination of the composite fibres at high temperatures. This paper investigates the thermal decomposition process, structures and morphologies of the electrospun composite fibres and the calcined Ni_(0.5)Zn_(0.5)Fe_2O_4 nanofibres at different temperatures by thermogravimetric and differential thermal analysis, x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The magnetic behaviour of the resultant nanofibres was studied by a vibrating sample magnetometer, It is found that the grain sizes of the nanofibres increase significantly and the nanofibre morphology gradually transforms from a porous structure to a necklace-like nanostructure with the increase of calcination temperature. The Ni_(0.5)Zn_(0.5)Fe_2O_4 nanofibres obtained at 1000℃ for 2 h are characterized by a necklace-like morphology and diameters of 100-200 nm. The saturation magnetization of the random Ni_(0.5)Zn_(0.5)Fe_2O_4 nanofibres increases from 46.5 to 90.2 emu/g when the calcination temperature increases from 450 to 1000℃. The coercivity reaches a maximum value of 11.0 kA/m at a calcination temperature of 600℃. Due to the shape anisotropy, the aligned Ni_(0.5)Zn_(0.5)Fe_2O_4 nanofibres exhibit an obvious magnetic anisotropy and the ease magnetizing direction is parallel to the nanofibre axis.

  7. Operational assimilation of ASCAT surface soil wetness at the Met Office

    Directory of Open Access Journals (Sweden)

    I. Dharssi

    2011-04-01

    Full Text Available Currently, no extensive global soil moisture observation network exists. Therefore, the Met Office global soil moisture analysis scheme has instead used observations of screen temperature and humidity. A number of new space-borne remote sensing systems, operating at microwave frequencies, have been developed that provide a more direct retrieval of surface soil moisture. These systems are attractive since they provide global data coverage and the horizontal resolution is similar to weather forecasting models. Several studies show that measurements of normalised backscatter (surface soil wetness from the Advanced Scatterometer (ASCAT on the meteorological operational (MetOp satellite contain good quality information about surface soil moisture. This note describes methods to convert ASCAT surface soil wetness measurements to volumetric surface soil moisture together with bias correction and quality control. A computationally efficient nudging scheme is used to assimilate the ASCAT volumetric surface soil moisture data into the Met Office global soil moisture analysis. This ASCAT nudging scheme works alongside a soil moisture nudging scheme that uses observations of screen temperature and humidity. Trials, using the Met Office global Unified Model, of the ASCAT nudging scheme show a positive impact on forecasts of screen temperature and humidity for the tropics, North America and Australia. A comparison with in-situ soil moisture measurements from the US also indicates that assimilation of ASCAT surface soil wetness improves the soil moisture analysis. Assimilation of ASCAT surface soil wetness measurements became operational during July 2010.

  8. A temperature prediction-correction method for estimating surface soil heat flux from soil temperature and moisture data

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Surface soil heat flux is a component of surface energy budget and its estimation is needed in land-atmosphere interaction studies. This paper develops a new simple method to estimate soil heat flux from soil temperature and moisture observations. It gives soil temperature profile with the thermal diffusion equation and, then, adjusts the temperature profile with differences between observed and computed soil temperatures. The soil flux is obtained through integrating the soil temperature profile. Compared with previous methods, the new method does not require accurate thermal conductivity. Case studies based on observations, synthetic data, and sensitivity analyses show that the new method is preferable and the results obtained with it are not sensitive to the availability of temperature data in the topsoil. In addition, we pointed out that the soil heat flux measured with a heat-plate can be quite erroneous in magnitude though its phase is accurate.

  9. Oxygen Storaging Behaviour of the Perovskite Ceramic (Ca{sub 0.5}Sr{sub 0.5})(Mn{sub 0.5}Fe{sub 0.5})O{sub 3-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Kaps, Ch; Heidenreich, M, E-mail: christian.kaps@uni-weimar.de [Bauhaus-University Weimar, Chair of Building and Materials Chemistry Coudraystrasse 13C, D-99423 Weimar (Germany)

    2011-05-15

    The perovskite ceramic (Ca{sub 0.5}Sr{sub 0.5})(Mn{sub 0.5}Fe{sub 0.5})O{sub 3-{delta}} is investigated in respect to the oxygen storaging behaviour in the temperature range from 500 to 900deg. C. An optimum discharging (Ar) / charging (air) process with a change of oxygen content 3-{delta} (2,61 / 2,77) was founded at 800deg. C, confirmed also by the short-time discharging rates. In this temperature range the transition from the Fe{sup 4+}/Fe{sup 3+} to the Mn{sup 4+}/Mn{sup 3+} redox-equilibrium occurs. The ceramic material exhibits chemical stability against the flue gas components CO{sub 2} and SO{sub 2}.

  10. Giant strain in lead-free piezoceramics Bi0.5Na0.5TiO3-BaTiO3-K0.5Na0.5NbO3 system

    Science.gov (United States)

    Zhang, Shan-Tao; Kounga, Alain Brice; Aulbach, Emil; Ehrenberg, Helmut; Rödel, Jürgen

    2007-09-01

    Piezoelectric actuators convert electrical into mechanical energy and are implemented for many large-scale applications such as piezoinjectors and ink jet printers. The performance of these devices is governed by the electric-field-induced strain. Here, the authors describe the development of a class of lead-free (0.94-x)Bi0.5Na0.5TiO3-0.06BaTiO3-xK0.5Na0.5NbO3 ceramics. These can deliver a giant strain (0.45%) under both unipolar and bipolar field loadings, which is even higher than the strain obtained with established ferroelectric Pb(Zr ,Ti)O3 ceramics and is comparable to strains obtained in Pb-based antiferroelectrics.

  11. On the Soil Roughness Parameterization Problem in Soil Moisture Retrieval of Bare Surfaces from Synthetic Aperture Radar.

    Science.gov (United States)

    Verhoest, Niko E C; Lievens, Hans; Wagner, Wolfgang; Álvarez-Mozos, Jesús; Moran, M Susan; Mattia, Francesco

    2008-07-15

    Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unless accurate surface roughness parameter values are available, retrieving soil moisture from radar backscatter usually provides inaccurate estimates. The characterization of soil roughness is not fully understood, and a large range of roughness parameter values can be obtained for the same surface when different measurement methodologies are used. In this paper, a literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture. A number of suggestions were made for resolving issues in roughness parameterization and studying the impact of these roughness problems on the soil moisture retrieval accuracy and scale.

  12. Describing soil surface microrelief by crossover length and fractal dimension

    Directory of Open Access Journals (Sweden)

    E. Vidal Vázquez

    2007-05-01

    Full Text Available Accurate description of soil surface topography is essential because different tillage tools produce different soil surface roughness conditions, which in turn affects many processes across the soil surface boundary. Advantages of fractal analysis in soil microrelief assessment have been recognised but the use of fractal indices in practice remains challenging. There is also little information on how soil surface roughness decays under natural rainfall conditions. The objectives of this work were to investigate the decay of initial surface roughness induced by natural rainfall under different soil tillage systems and to compare the performances of a classical statistical index and fractal microrelief indices. Field experiments were performed on an Oxisol at Campinas, São Paulo State (Brazil. Six tillage treatments, namely, disc harrow, disc plow, chisel plow, disc harrow + disc level, disc plow + disc level and chisel plow + disc level were tested. Measurements were made four times, firstly just after tillage and subsequently with increasing amounts of natural rainfall. Duplicated measurements were taken per treatment and date, yielding a total of 48 experimental surfaces. The sampling scheme was a square grid with 25×25 mm point spacing and the plot size was 1350×1350 mm, so that each data set consisted of 3025 individual elevation points. Statistical and fractal indices were calculated both for oriented and random roughness conditions, i.e. after height reading have been corrected for slope and for slope and tillage tool marks. The main drawback of the standard statistical index random roughness, RR, lies in its no spatial nature. The fractal approach requires two indices, fractal dimension, D, which describes how roughness changes with scale, and crossover length, l, specifying the variance of surface microrelief at a reference scale. Fractal parameters D and l, were estimated by two independent self-affine models

  13. Effect of Pr Addition on Properties of Sn-0.5Ag-0.7Cu-0.5Ga Lead-Free Solder

    Science.gov (United States)

    Xujing, Nan; Songbai, Xue; Peizhuo, Zhai; Dongxue, Luo

    2016-10-01

    In this paper, the effect of Pr addition on the microstructure and properties of Sn-0.5Ag-0.7Cu-0.5Ga lead-free solder was investigated. It was found that the properties of Sn-0.5Ag-0.7Cu-0.5Ga- xPr solder, such as wettability and mechanical properties, could be obviously improved, and the optimal content of Pr was about 0.06 wt.%. The microstructure of Sn-0.5Ag-0.7Cu-0.5Ga-0.06Pr solder showed that the β-Sn matrix and intermetallic compound (IMC) grains were significantly refined, and refinement and homogenization of the microstructure achieved maximum efficiency, which played the role of fine grain strengthening and second phase strengthening. However, as the content of Pr exceeded 0.06 wt.%, some uneven distributed black phases of PrSn3 were found in the β-Sn matrix, which seriously worsened the microstructure and properties of the solders. As a surface-active element, the segregation of Pr at the molten solder interface could give rise to decreasing the interface tension. Consequently, adding a suitable amount of Pr could play a positive role in improving the properties of the solders.

  14. Electronic structure of a new layered bismuth oxyselenide superconductor: LaO0.5F0.5BiSe2.

    Science.gov (United States)

    Xia, M; Jiang, J; Niu, X H; Liu, J Z; Wen, C H P; Lu, H Y; Lou, X; Pu, Y J; Huang, Z C; Zhu, Xiyu; Wen, H H; Xie, B P; Shen, D W; Feng, D L

    2015-07-22

    LaO(0.5)F(0.5)BiSe(2) is a new layered superconductor discovered recently, which shows the superconducting transition temperature of 3.5 K. With angle-resolved photoemission spectroscopy, we study the electronic structure of LaO(0.5)F(0.5)BiSe(2) comprehensively. Two electron-like bands are located around the X point of the Brillouin zone, and the outer pockets connect with each other and form large Fermi surface around Γ and M. These bands show negligible k(z) dispersion, indicating their two-dimensional nature. Based on the Luttinger theorem, the carrier concentration is about 0.53 e(-) per unit cell, close to its nominal value. Moreover, the photoemission data and the band structure calculations agree very well, and the renormalization factor is nearly 1.0, indicating the electron correlations in this material are rather weak. Our results suggest that LaO(0.5)F(0.5)BiSe(2) is a conventional BCS superconductor without strong electron correlations.

  15. Research on preparation of layered LiNi0.5 Mn0.5O2

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    An O2-type layered LiNi0. 5 Mn0. 5 O2 was prepared by rapidly-quenched method, and the structural feature was studied by X-Ray Diffraction. The material synthesized at 950℃ was with a single O2-type structure. Charge and discharge in a voltage range of 2.0-4.35V, the discharge specific capacity of material at the 1st cycle is 143.1 mAh/g in a current density of 0.5 mA/cm2 , and the plot of discharge was with two voltage plat at 3.6 V and 2.8V.

  16. Synthesis of La0.5Ca0.5Ni0.5Fe0.5O3 catalysts and its catalytic performance in the pyrolysis of biomass%La_(0.5)Ca_(0.5)Ni_(0.5)Fe_(0.5)O_3催化剂的制备及其对生物质热解特性的影响

    Institute of Scientific and Technical Information of China (English)

    李倩; 刘石明; 成功; 齐方杰; 蔡海燕

    2012-01-01

    La0.5Ca0.5Ni0.5Fe0.5O3(LCNF) nano-catalyst was prepared by co-precipitation method.X-ray diffraction(XRD),scanning electron microscope(SEM),and Thermogravimetric Analysis(TG-DTA) were adopted to characterize the synthesized catalysts.Results shows that calcination at 600℃ for 6h was the suitable conditions for the synthesis of LCNF nano-powders when ammonium carbonate was used as the co-precipitation agent and polyethylene glycol(PEG) as the dispersant.Pyrolysis gas produced from the catalytic pyrolysis of biomass was studied in a fixed bed reactor using LCNF as the catalyst.Compared to the conventional pyrolysis process,the yields of tar reduced by 12.4%,and the yields of gas increased by 14.0%.At the same time,the content of CO in the gas product increased from 33.8% to 38.5% while CH4 from 15.1% to 18.4%.Therefore,the LCNF shows relatively good tar removal property,which is a promising catalyst in the gasification/prolysis of biomass.%采用共沉淀法制备了La0.5Ca0.5Ni0.5Fe0.5O3纳米粉体,并通过XRD、SEM、TG-DTA等手段对所合成的样品进行了分析和表征.结果表明,采用碳酸铵作为共沉淀剂、聚乙二醇为分散剂,在600℃下煅烧6h可作为实验制备该催化剂粉体的最优条件.用实验室自制热解催化炉验证其对生物质热解的效果,实验结果表明,采用La0.5Ca0.5Ni0.5Fe0.5O3催化剂,生物质热解过程中焦油产量降低了12.4%,气体产率提高了14.0%,气体产物中一氧化碳、甲烷含量分别从33.8%和15.1%提高到了38.5%和18.4%,燃气的品质大大提升.

  17. Assimilation of neural network soil moisture in land surface models

    Science.gov (United States)

    Rodriguez-Fernandez, Nemesio; de Rosnay, Patricia; Albergel, Clement; Aires, Filipe; Prigent, Catherine; Kerr, Yann; Richaume, Philippe; Muñoz-Sabater, Joaquin; Drusch, Matthias

    2017-04-01

    In this study a set of land surface data assimilation (DA) experiments making use of satellite derived soil moisture (SM) are presented. These experiments have two objectives: (1) to test the information content of satellite remote sensing of soil moisture for numerical weather prediction (NWP) models, and (2) to test a simplified assimilation of these data through the use of a Neural Network (NN) retrieval. Advanced Scatterometer (ASCAT) and Soil Moisture and Ocean Salinity (SMOS) data were used. The SMOS soil moisture dataset was obtained specifically for this project training a NN using SMOS brightness temperatures as input and using as reference for the training European Centre for Medium-Range Weather Forecasts (ECMWF) H-TESSEL SM fields. In this way, the SMOS NN SM dataset has a similar climatology to that of the model and it does not present a global bias with respect to the model. The DA experiments are computed using a surface-only Land Data Assimilation System (so-LDAS) based on the HTESSEL land surface model. This system is very computationally efficient and allows to perform long surface assimilation experiments (one whole year, 2012). SMOS NN SM DA experiments are compared to ASCAT SM DA experiments. In both cases, experiments with and without 2 m air temperature and relative humidity DA are discussed using different observation errors for the ASCAT and SMOS datasets. Seasonal, geographical and soil-depth-related differences between the results of those experiments are presented and discussed. The different SM analysed fields are evaluated against a large number of in situ measurements of SM. On average, the SM analysis gives in general similar results to the model open loop with no assimilation even if significant differences can be seen for specific sites with in situ measurements. The sensitivity to observation errors to the SM dataset slightly differs depending on the networks of in situ measurements, however it is relatively low for the tests

  18. A Variational Method for Estimating Near-Surface Soil Moisture and Surface Heat Fluxes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shuwen; ZHANG Weidong; QIU Chongjian

    2007-01-01

    A variational data assimilation method is proposed to estimate the near-surface soil moisture and surface sensible and latent heat fluxes. The method merges the five parts into a cost function, I.e., the differences of wind, potential temperature, and specific humidity gradient between observations and those computed by the profile method, the difference of latent heat fluxes calculated using the ECMWF land surface evaporation scheme and the profile method, and a weak constraint for surface energy balance. By using an optimal algorithm, the best solutions are found. The method is tested with the data collected at Feixi Station (31.41°N, 117.08°E) supported by the China Heavy Rain Experiment and Study (HeRES) during 7-30 June 2001. The results show that estimated near-surface soil moistures can quickly respond to rainfall, and their temporal variation is consistent with that of measurements of average soil moisture over 15-cm top depth with a maximum error less than 0.03 m3 m-3. The surface heat fluxes calculated by this method are consistent with those by the Bowen ratio method, but at the same time it can overcome the instability problem occurring in the Bowen ratio method when the latter is about -1. Meanwhile, the variational method is more accurate than the profile method in terms of satisfying the surface energy balance. The sensitivity tests also show that the variational method is the most stable one among the three methods.

  19. Spatial and temporal distribution of cyanobacterial soil crusts in the Kalahari: Implications for soil surface properties

    Science.gov (United States)

    Thomas, A. D.; Dougill, A. J.

    2007-03-01

    Localised patterns of erosion and deposition in vegetated semi-arid rangelands have been shown to influence ecological change and biogeochemical cycles. In the flat, vegetated Kalahari rangelands of Southern Africa the factors regulating erodibility of the fine sand soils and the erosivity of wind regimes require further investigation. This paper reports on the spatial and temporal patterns of cyanobacterial soil crust cover from ten sites at five sampling locations in the semi-arid Kalahari and discusses the likely impact on factors regulating surface erodibility and erosivity. Cyanobacterial soil crust cover on Kalahari Sand varied between 11% and 95% of the ground surface and was higher than previously reported. Cover was inversely related to grazing with the lowest crust cover found close to boreholes and the highest in the Game Reserve and Wildlife Management Zone. In grazed areas, crusts form under the protective canopies of the thorny shrub Acacia mellifera. Fenced plot data showed that crusts recover quickly from disturbance, with a near complete surface crust cover forming within 15 months of disturbance. Crust development is restricted by burial by wind blown sediment and by raindrop impact. Crusts had significantly greater organic matter and total nitrogen compared to unconsolidated surfaces. Crusts also significantly increased the compressive strength of the surface (and thus decreased erodibility) and changed the surface roughness. Establishing exactly how these changes affect aeolian erosion requires further process-based studies. The proportion of shear velocity acting on the surface in this complex mixed bush-grass-crust environment will be the key to understanding how crusts affect erodibility.

  20. Relations between soil surface roughness, tortuosity, tillage treatments, rainfall intensity and soil and water losses from a red yellow latosol

    Directory of Open Access Journals (Sweden)

    Julieta Bramorski

    2012-08-01

    Full Text Available The soil surface roughness increases water retention and infiltration, reduces the runoff volume and speed and influences soil losses by water erosion. Similarly to other parameters, soil roughness is affected by the tillage system and rainfall volume. Based on these assumptions, the main purpose of this study was to evaluate the effect of tillage treatments on soil surface roughness (RR and tortuosity (T and to investigate the relationship with soil and water losses in a series of simulated rainfall events. The field study was carried out at the experimental station of EMBRAPA Southeastern Cattle Research Center in São Carlos (Fazenda Canchim, in São Paulo State, Brazil. Experimental plots of 33 m² were treated with two tillage practices in three replications, consisting of: untilled (no-tillage soil (NTS and conventionally tilled (plowing plus double disking soil (CTS. Three successive simulated rain tests were applied in 24 h intervals. The three tests consisted of a first rain of 30 mm/h, a second of 30 mm/h and a third rain of 70 mm/h. Immediately after tilling and each rain simulation test, the surface roughness was measured, using a laser profile meter. The tillage treatments induced significant changes in soil surface roughness and tortuosity, demonstrating the importance of the tillage system for the physical surface conditions, favoring water retention and infiltration in the soil. The increase in surface roughness by the tillage treatments was considerably greater than its reduction by rain action. The surface roughness and tortuosity had more influence on the soil volume lost by surface runoff than in the conventional treatment. Possibly, other variables influenced soil and water losses from the no-tillage treatments, e.g., soil type, declivity, slope length, among others not analyzed in this study.

  1. Thermally activated flux flow in FeSe0.5Te0.5 superconducting single crystal

    Science.gov (United States)

    Hamad, R. M.; Kayed, T. S.; Kunwar, S.; Ziq, Kh A.

    2017-07-01

    The current-voltage (J-E) isotherms of single crystal FeSe0.5Te0.5 sample have been measured at several temperatures near the transition temperature (Tc) and under applied magnetic fields (H). A power law (E ˜ Jβ ) has been used to fit the data and evaluate the activation energy Uo (T) using β = Uo/kBT. At low current density (J > Jc vortex flux flow (FF) behavior is expected. The effects of applied magnetic field on FF and TAFF also been investigated. We found that Uo(FF) was reduced with by about an order of magnitude in magnetic fields as low as ˜1.5 Tesla-the reduction in Uo(TAFF) is even faster than in Uo(FF)-hence reflecting the low pinning nature (defects, vacancies etc.) of FeSe0.5Te0.5 superconductor.

  2. Synthesis and Magnetostriction of (CexTb1-x)0.5Pr0.5Fe2 Compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The structural and magnetostrictive properties of (CexTb1-x)0.5Pr0.5Fe2 were investigated. Ce concentration must exceed x=0.6 in order to obtain the pure Laves phase. The magnetostriction and anisotropy constant increase with the Tb-content in this system. The anisotropy value of PrFe2 is lower than that of isostructural DyFe2. From the X-ray step-scanned data we found that λ111 of PrFe2 is 1310×10-6. A large increase of magnetostriction can be observed under a small prestress of 6 MPa for Ce0.5Pr0.5Fe2.

  3. Superconductivity induced by In substitution into the topological crystalline insulator Pb0.5Sn0.5Te

    Science.gov (United States)

    Zhong, R. D.; Schneeloch, J. A.; Liu, T. S.; Camino, F. E.; Tranquada, J. M.; Gu, G. D.

    2014-07-01

    Indium substitution turns the topological crystalline insulator (TCI) Pb0.5Sn0.5Te into a possible topological superconductor. To investigate the effect of the indium concentration on the crystal structure and superconducting properties of (Pb0.5Sn0.5)1-xInxTe, we have grown high-quality single crystals using a modified floating-zone method and have performed systematic studies for indium content in the range 0≤x≤0.35. We find that the single crystals retain the rocksalt structure up to the solubility limit of indium (x ˜0.30). Experimental dependencies of the superconducting transition temperature (Tc) and the upper critical magnetic field (Hc2) on the indium content x have been measured. The maximum Tc is determined to be 4.7 K at x =0.30, with μ0Hc2(T =0)≈5 T.

  4. A coprecipitation technique to prepare Sr0.5Ba0.5Nb2O6

    Indian Academy of Sciences (India)

    A Vadivel Murugan; A B Gaikwad; V Samuel; V Ravi

    2006-06-01

    An aqueous mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and strontium ions as oxalates and niobium ions as hydroxide under basic conditions. This precursor on calcining at 750°C yielded Sr0.5Ba0.5Nb2O6 phase. This is a much lower temperature than that prepared by traditional solid state method (1000°C) as reported for the formation of Sr0.5Ba0.5Nb2O6 (SBN). Transmission electron microscopic (TEM) investigations revealed that the average particle size was 80 nm for the calcined powders. The room temperature dielectric constant at 1 kHz was found to be 1100. The ferroelectric hysteresis loop parameters of these samples were also studied.

  5. Enhancement of transition temperature in FexSe0.5Te0.5 film via iron vacancies

    Science.gov (United States)

    Zhuang, J. C.; Yeoh, W. K.; Cui, X. Y.; Kim, J. H.; Shi, D. Q.; Shi, Z. X.; Ringer, S. P.; Wang, X. L.; Dou, S. X.

    2014-06-01

    The effects of iron deficiency in FexSe0.5Te0.5 thin films (0.8 ≤ x ≤ 1) on superconductivity and electronic properties have been studied. A significant enhancement of the superconducting transition temperature (TC) up to 21 K was observed in the most Fe deficient film (x = 0.8). Based on the observed and simulated structural variation results, there is a high possibility that Fe vacancies can be formed in the FexSe0.5Te0.5 films. The enhancement of TC shows a strong relationship with the lattice strain effect induced by Fe vacancies. Importantly, the presence of Fe vacancies alters the charge carrier population by introducing electron charge carriers, with the Fe deficient film showing more metallic behavior than the defect-free film. Our study provides a means to enhance the superconductivity and tune the charge carriers via Fe vacancy, with no reliance on chemical doping.

  6. Direct Synthesis of (K0.5Na0.5NbO3 Powders by Mechanochemical Method

    Directory of Open Access Journals (Sweden)

    Nguyen Duc Van

    2013-01-01

    Full Text Available The synthesis and structural properties of lead-free piezoelectric (K0.5Na0.5NbO3 powders prepared by mechanochemical method using Nb2O5, K2CO3, and Na2CO3 as starting materials were reported. X-ray diffraction, infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy were used to characterize the prepared samples. Results showed that, for the first time, by selecting the milling speed of 600 rpm and the ball-to-powder weight ratio of 35 : 1 as milling parameters, pure (K0.5Na0.5NbO3 crystalline phase was obtained directly in the as-milled samples after 5 h of milling time. The existence of a carbonato complex between CO32− and Nb5+ ions as an intermediate species of the formation of (K0.5Na0.5NbO3 was also found.

  7. Structure and magnetic properties of colossal magnetoresistance compound Tb0.5Sr0.5CoO3

    Indian Academy of Sciences (India)

    J S Srikiran; A B Shinde; P S R Krishna

    2004-08-01

    The structure and the magnetic properties of the doped rare earth cobaltite systems are of recent interest owing to the CMR phenomenon that occur in them. In this paper, we investigate the structure and magnetic properties of Tb0.5Sr0.5CoO3 solid solution, for the first time, using neutron powder diffraction technique. The sample Tb0.5Sr0.5CoO3 is found to crystallize in orthorhombic (Pbnm) symmetry. The unit cell volume and Co-O bond length reduce with temperature. The calculated bandwidth obtained from structural parameters turns out to be 0.989 eV. Low temperature neutron diffraction profiles exhibit a magnetic contribution to the fundamental Bragg peaks indicating a ferromagnetic ordering below c. The results are compared with Co-O-Co bond angles and Co-O bond length of La0.5Sr0.5CoO3, highlighting the ionic size effects on substitution of Tb ion for La in the compound.

  8. Electrical properties of BaY 0.5Nb 0.5O 3 ceramic: Impedance spectroscopy analysis

    Science.gov (United States)

    Prasad, K.; Bhagat, S.; Priyanka; AmarNath, K.; Chandra, K. P.; Kulkarni, A. R.

    2010-09-01

    Lead-free perovskite BaY 0.5Nb 0.5O 3 was prepared by conventional ceramic technique at 1375 °C/7 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were derived from the experimental results using FullProf software. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm3¯m. EDAX, X-ray mapping and SEM studies were carried to study the quality and purity of the compound. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. To find a correlation between the response of the real system and idealized model circuit composed of discrete electrical components, the model fittings were presented using the impedance data. Electric modulus studies supported the hopping type of conduction in BaY 0.5Nb 0.5O 3. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in BaY 0.5Nb 0.5O 3. The ac conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy of the compound.

  9. Three-Dimensional Zn0.5Cd0.5S/Reduced Graphene Oxide Hybrid Aerogel: Facile Synthesis and the Visible-Light-Driven Photocatalytic Property for Reduction of Cr(VI in Water

    Directory of Open Access Journals (Sweden)

    Wei Xiao

    2016-01-01

    Full Text Available A series of three-dimensional ZnxCd1-xS/reduced graphene oxide (ZnxCd1-xS/RGO hybrid aerogels was successfully synthesized based on a one-pot hydrothermal approach, which were subsequently used as visible-light-driven photocatalysts for photoreduction of Cr(VI in water. Over 95% of Cr(VI was photoreduced by Zn0.5Cd0.5S/RGO aerogel material within 140 min, and such photocatalytic performance was superior to that of other ZnxCd1-xS/RGO aerogel materials (x≠0.5 and bare Zn0.5Cd0.5S. It was assumed that the enhanced photocatalytic activity of Zn0.5Cd0.5S/RGO aerogel was attributed to its high specific surface area and the preferable synergetic catalytic effect between Zn0.5Cd0.5S and RGO. Besides, Zn0.5Cd0.5S/RGO aerogel materials were robust and durable enough so that they could be reused several times with merely limited loss of photocatalytic activity. The chemical composition, phase, structure, and morphology of Zn0.5Cd0.5S/RGO aerogel material were carefully examined by a number of techniques like XRD, SEM, TEM, BET, Raman characterizations, and so on. It was found that Zn0.5Cd0.5S/RGO aerogel possessed hierarchically porous architecture with the specific surface area as high as 260.8 m2 g−1. The Zn0.5Cd0.5S component incorporated in Zn0.5Cd0.5S/RGO aerogel existed in the form of solid solution nanoparticles, which were uniformly distributed in the RGO matrix.

  10. Photolysis of polycyclic aromatic hydrocarbons on soil surfaces under UV irradiation

    Institute of Scientific and Technical Information of China (English)

    Chengbin Xu; Dianbo Dong; Xuelian Meng; Xin Su; Xu Zheng; Yaoyao Li

    2013-01-01

    Photolysis of some polycyclic aromatic hydrocarbons (PAHs) on soil surfaces may play an important role in the fate of PAHs in the environment.Photolysis of PAHs on soil surfaces under UV irradiation was investigated.The effects of oxygen,irradiation intensity and soil moisture on the degradation of the three PAHs were observed.The results showed that oxygen,soil moisture and irradiation intensity enhanced the photolysis of the three PAHs on soil surfaces.The degradation of the three PAHs on soil surfaces is related to their absorption spectra and the oxidation-half-wave potential.The photolysis of PAHs on soil surfaces in the presence of oxygen followed pseudo first-order kinetics.The photolysis half-lives ranged from 37.87 days for benzo[a]pyrene to 58.73 days for phenanthrene.The results indicate that photolysis is a successful way to remediate PAHs-contaminated soils.

  11. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Ligotke, M.W.; Klopfer, D.C.

    1990-08-01

    Protective barriers have been identified as integral components of plans to isolate defense waste on the Hanford Site. The use of natural materials to construct protective barriers over waste site is being considered. Design requirements for protective barriers include preventing exposure of buried waste, and restricting penetration or percolation of surface waters through the waste zone. Studies were initiated to evaluate the effects of wind erosion on candidate protective barrier surfaces. A wind tunnel was used to provide controlled erosive stresses and to investigate the erosive effects of wind forces on proposed surface layers for protective barriers. Mixed soil and gravel surfaces were prepared and tested for resistance to wind erosion at the Pacific Northwest Laboratory Aerosol Wind Tunnel Research Facility. These tests were performed to investigate surface deflation caused by suspension of soil from various surface layer configurations and to provide a comparison of the relative resistance of the different surfaces to wind erosion. Planning, testing, and analyzing phases of this wind erosion project were coordinated with other tasks supporting the development of protective barriers. These tasks include climate-change predictions, field studies and modeling efforts. This report provides results of measurements of deflation caused by wind forces over level surfaces. Section 2.0 reviews surface layer characteristics and previous relevant studies on wind erosion, describes effects of erosion, and discusses wind tunnel modeling. Materials and methods of the wind tunnel tests are discussed in Section 3.0. Results and discussion are presented in Section 4.0, and conclusions and recommendations Section 5.0. 53 refs., 29 figs., 7 tabs.

  12. Use of Aloe vera shell ash supported Ni0.5Zn0.5Fe2O4 magnetic nanoparticles for removal of Pb (II from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Samira Namavari

    2016-03-01

    Full Text Available Background: Lead (Pb is a heavy metal that is widely utilized in industries. It contaminates soil and groundwater. Its non-biodegradability, severe toxicity, carcinogenicity, ability to accumulate in nature and contaminate groundwater and surface water make this toxic heavy metal extremely dangerous to living beings and the environment. Therefore, technical and economic methods of removing Pb are of great importance. This study evaluated the efficiency of Ni0.5Zn0.5Fe2O4 magnetic nanoparticles supported by Aloe vera shell ash in removing Pb from aqueous environments. Methods: The adsorbent was characterized by several methods, including x-ray diffraction (XRD, scanning electron microscopy (SEM, and Fourier transform infrared spectroscopy (FT-IR. Then, the potential of Aloe vera shell ash-supported Ni0.5Zn0.5Fe2O4 magnetic nanoparticles to adsorb Pb (II was investigated. To determine the amount of lead absorbed by this adsorbent, different pHs (2, 4, 5, and 6, adsorbent doses (0.01-0.40 g, Pb concentrations (5, 10, 20, 30, 40, 50, 60, 80, 100, 200, 300, and 600 mg/L, and exposure times (0, 5, 10, 15, 20, 30, 40, 50, and 60 minutes until reaching equilibrium were tested using an atomic absorption spectrometer (Varian-AA240FS. Residual concentrations of Pb were read. Results: The results show that a time of 15 minutes, pH value of 9, and adsorbent dose of 0.2 g are the optimum conditions for Pb (II removal by this adsorption process. Increasing the initial concentration of Pb (II from 5 to 600 mg/L decreased removal efficiency from 98.8% to 73%. The experimental data fit well into the Freundlich isotherm model (R2 = 0.989. Conclusion: Ni0.5Zn0.5Fe2O4 magnetic nanoparticles supported by Aloe vera shell ash comprise a low-cost, simple, and environmentally benign procedure. The maximum monolayer adsorption capacity based on the Langmuir isotherm (R2 = 0.884 is 47.2 mg g-1. The prepared magnetic adsorbent can be well dispersed in aqueous solutions and

  13. Far-infrared conductivity measurements of pair breaking in superconducting Nb 0.5 Ti 0.5 N thin films induced by an external magnetic field.

    Science.gov (United States)

    Xi, Xiaoxiang; Hwang, J; Martin, C; Tanner, D B; Carr, G L

    2010-12-17

    We report the complex optical conductivity of a superconducting thin film of Nb 0.5 Ti 0.5 N in an external magnetic field. The field was applied parallel to the film surface and the conductivity extracted from far-infrared transmission and reflection measurements. The real part shows the superconducting gap, which we observe to be suppressed by the applied magnetic field. We compare our results with the pair-breaking theory of Abrikosov and Gor'kov and confirm directly the theory's validity for the optical conductivity.

  14. Oxidation Behavior of a Refractory NbCrMo0.5Ta0.5TiZr Alloy (Preprint)

    Science.gov (United States)

    2012-03-01

    smaller than the atomic radii of other elements in the fourth alloy, causes additional formation of a minor FCC Laves phase [10]. Due to strongly...pattern of the HIPd NbCrMo0.5Ta0.5TiZr alloy. A major BCC1 phase and two minor phases , BCC2 and FCC ( Laves ), were identified [10]. The lattice parameters...parallel to the sample surface develop in the regions of former BCC2 and Laves phases (between former BCC1 particles). The cracks are also extended

  15. Effect of grain size on charge and spin correlations in Bi0.5Ca0.5MnO3 manganite nanoparticles

    Science.gov (United States)

    Ade, Ramesh; Singh, Rajender

    2016-11-01

    In this work we report the electron spin resonance (ESR) and magnetization (M) studies to understand the effect of grain size (GS) on the charge ordering and spin correlations in Bi0.5Ca0.5MnO3 manganite synthesized by sol-gel method. The suppression of charge ordering (CO), long-range antiferromagnetic (AFM) state, shifting of ferromagnetic (FM)-cluster glass (CG) transition towards higher temperatures and evolution of different magnetic correlations with decrease in GS are discussed in view of the changes in surface to volume ratio of nano-grains.

  16. Solute leaching in a sandy soil with a water-repellent surface layer: a simulation.

    NARCIS (Netherlands)

    Rooij, de G.H.; Vries, de P.

    1996-01-01

    Many sandy soils in the Netherlands have a water-repellent surface layer covering a wettable soil with a shallow groundwater table. Fingers form in the water-repellent surface layer and rapidly transport water and solutes to the wettable soil in which the streamlines diverge. Although several field

  17. On the use of surface neutron-gamma gauges to estimate soil water content

    Energy Technology Data Exchange (ETDEWEB)

    Tominaga, T.T.; Cassaro, F.A.M.; Reichardt, K. E-mail: klaus@cena.usp.br; Bacchi, O.O.S.; Oliveira, J.C.M.; Timm, L.C

    2002-09-01

    Surface neutron-gamma gauges are handy instruments to measure soil water contents and bulk densities of surface layers. Although available for some decades, their optimal use is still not well established. This study is a contribution to improve their use, mainly in relation to calibration, and of the effect of soil dry bulk density on soil water content measurements.

  18. Impacts of snow and organic soils parameterization on northern Eurasian soil temperature profiles simulated by the ISBA land surface model

    Science.gov (United States)

    Decharme, Bertrand; Brun, Eric; Boone, Aaron; Delire, Christine; Le Moigne, Patrick; Morin, Samuel

    2016-04-01

    In this study we analyzed how an improved representation of snowpack processes and soil properties in the multilayer snow and soil schemes of the Interaction Soil-Biosphere-Atmosphere (ISBA) land surface model impacts the simulation of soil temperature profiles over northern Eurasian regions. For this purpose, we refine ISBA's snow layering algorithm and propose a parameterization of snow albedo and snow compaction/densification adapted from the detailed Crocus snowpack model. We also include a dependency on soil organic carbon content for ISBA's hydraulic and thermal soil properties. First, changes in the snowpack parameterization are evaluated against snow depth, snow water equivalent, surface albedo, and soil temperature at a 10 cm depth observed at the Col de Porte field site in the French Alps. Next, the new model version including all of the changes is used over northern Eurasia to evaluate the model's ability to simulate the snow depth, the soil temperature profile, and the permafrost characteristics. The results confirm that an adequate simulation of snow layering and snow compaction/densification significantly impacts the snowpack characteristics and the soil temperature profile during winter, while the impact of the more accurate snow albedo computation is dominant during the spring. In summer, the accounting for the effect of soil organic carbon on hydraulic and thermal soil properties improves the simulation of the soil temperature profile. Finally, the results confirm that this last process strongly influences the simulation of the permafrost active layer thickness and its spatial distribution.

  19. Light structures phototroph, bacterial and fungal communities at the soil surface.

    Directory of Open Access Journals (Sweden)

    Lawrence O Davies

    Full Text Available The upper few millimeters of soil harbour photosynthetic microbial communities that are structurally distinct from those of underlying bulk soil due to the presence of light. Previous studies in arid zones have demonstrated functional importance of these communities in reducing soil erosion, and enhancing carbon and nitrogen fixation. Despite being widely distributed, comparative understanding of the biodiversity of the soil surface and underlying soil is lacking, particularly in temperate zones. We investigated the establishment of soil surface communities on pasture soil in microcosms exposed to light or dark conditions, focusing on changes in phototroph, bacterial and fungal communities at the soil surface (0-3 mm and bulk soil (3-12 mm using ribosomal marker gene analyses. Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus. The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes. However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere.

  20. Comparison of 0.5% Bupivacaine and 0.5% Ropivacaine epidurally in lower limb orthopaedic surgeries

    Directory of Open Access Journals (Sweden)

    Ushma D. Shah

    2017-01-01

    Full Text Available Background: Ropivacaine in equi-potent concentrations with bupivacaine, the degree of motor blockade is less pronounced with ropivacaine, and there is a greater propensity for blocking pain transmitting A-delta and C fibres rather than A-α motor fibres. It appears to have most of the blocking characteristics of bupivacaine. So we have undertaken the study to compare ropivacaine 0.5% (20ml and bupivacaine 0.5% (20ml for epidural anaesthesia in patients undergoing lower limb orthopaedic surgeries. Methods: This double-blind, randomized study involves 60 patients who were undergone orthopaedic surgery, having ASA-I or ASA-II physical status. Out of 60, 30 patients received 20 ml of 0.5% ropivacaine and 30 patients received 20 ml of 0.5% bupivacaine at the L3, 4 interspace. Parameters measured were the onset time, duration and spread of sensory block, the onset time, peak time, duration and degree of motor block, the quality of anaesthesia and the heart rate and blood pressure profile during block onset. Results: Epidurally, Ropivacaine in comparison to Bupivacaine provides quicker onset, early peak effect and prolonged duration of sensory block and shorter duration of motor block. Ropivacaine provides prolonged effective analgesia. It reduces requirement of rescue analgesics and related side effects. Conclusions: Ropivacaine 0.5% is safer and effective alternative to Bupivacaine in epidural anaesthesia and post operative pain relief.

  1. X-Ray Groups of Galaxies at 0.5

    NARCIS (Netherlands)

    Tanaka, Masayuki; Finoguenov, Alexis; Lilly, Simon J.; Bolzonella, Micol; Carollo, C. Marcella; Contini, Thierry; Iovino, Angela; Kneib, Jean-Paul; Lamareille, Fabrice; Le Fevre, Olivier; Mainieri, Vincenzo; Presotto, Valentina; Renzini, Alvio; Scodeggio, Marco; Silverman, John D.; Zamorani, Gianni; Bardelli, Sandro; Bongiorno, Angela; Caputi, Karina; Cucciati, Olga; de la Torre, Sylvain; de Ravel, Loic; Franzetti, Paolo; Garilli, Bianca; Kampczyk, Pawel; Knobel, Christian; Kovac, Katarina; Le Borgne, Jean-Francois; Le Brun, Vincent; Lopez-Sanjuan, Carlos; Maier, Christian; Mignoli, Marco; Pello, Roser; Peng, Yingjie; Perez-Montero, Enrique; Tasca, Lidia; Tresse, Laurence; Vergani, Daniela; Zucca, Elena; Barnes, Luke; Bordoloi, Rongmon; Cappi, Alberto; Cimatti, Andrea; Coppa, Graziano; Koekemoer, Anton M.; McCracken, Henry J.; Moresco, Michele; Nair, Preethi; Oesch, Pascal; Pozzetti, Lucia; Welikala, Niraj

    2012-01-01

    We present a photometric and spectroscopic study of galaxies at 0.5

  2. Structural And Electrical Properties oF (La0.5-xPrxBa0.5)(Mn0.5Ti0.5)O3 Perovskite

    Science.gov (United States)

    Alias, Nor Hayati; Shaari, Abdul Halim; Wan Yusoff, Wan Mohd Daud; Mahmood, Che Seman

    2010-01-01

    A single phase monoclinic new perovskite based titano-manganite (La0.5-xPrxBa0.5)(Mn0.5Ti0.5)O3 has been successfully prepared by ceramic solid-state technique at sintering temperature of 1300° C. The concentration of Pr (Praseodymium), x, in molar proportion in A site has been varied as x = 0, 0.02 and 0.2. Analysis has been carried out to determine the electrical properties of the synthesized material at frequency ranging from 5 Hz to 1 MHz; and at temperature range between 25° C to 200° C. It is found that Pr addition promoted liquid phase sintering diffusion, porosity and agglomeration formation at 1300° C. Dual relaxation is observed in unsubstituted Pr sample x = 0 and high Pr substituted sample x = 0.2. This phenomenon was a combinational contribution from a quasi dc (QDC) or low frequency dispersion (LFD), two cole-cole relaxational responses and a resistor. While low concentrated Pr substituted sampled x = 0.02 shows a combinational contribution from a quasi dc (QDC) or low frequency dispersion (LFD), single cole-cole relaxational response and a resistor at room temperature. Pr substitution at x = 0 (max 12000) and x = 0.2 (max 16000) showed high dielectric values compared to low substituted sample x = 0.02. Variation of dielectric loss tangent (tan δ) are observed for all samples at temperature ranged studied.

  3. Structural, Dielectric and Complex Impedance Spectroscopy Studies of Lead Free Ca0.5 +xNd0.5-x(Ti0.5Fe0.5)O3

    Institute of Scientific and Technical Information of China (English)

    M.R.Shah; A.K.M.Akther Hossain

    2013-01-01

    Structural and various electrical properties of polycrystalline Ca0.5+xNd0.5-x(Ti0.5Fe0.5)O3,prepared by standard solid state reaction technique,were studied.Formation of single phase orthorhombic structure of the compositions was confirmed by X-ray diffraction study.The composition dependence of lattice parameters,density and microstructural study show that they vary significantly with Ca content.The dielectric measurements were carried out at room temperature as function of frequency and composition.The experimental results reveal that the dielectric constant (ε') increases with increasing Ca content.Similar behavior is observed for the dielectric loss (tanδ) and ac conductivity (σac).In complex impedance analysis it is observed that the real part (Z') vs imaginary part (Z") graph exhibits a tendency of formation of a single semicircular arc for each composition of samples.Different parameters were determined by fitting the experimental data in Cole-Cole empirical formula.A dominance of grain boundary resistance (Rgb) is observed.The Rgb decreases with increasing Ca content.The high ε' observed in present samples are suitablefor fabrication of devices.

  4. Analog circuit design techniques at 0.5V

    CERN Document Server

    Chatterjee, Shouri; Stanic, Nebojša

    2010-01-01

    This book tackles challenges for the design of analog integrated circuits that operate from ultra-low power supply voltages (down to 0.5V). Coverage demonstrates the signal processing circuit and circuit biasing approaches through the design of operational transconductance amplifiers (OTAs). These amplifiers are then used to build analog system functions including continuous time filter and a sample and hold amplifier.

  5. Electric properties of high strain textured Na 0.5Bi 0.5TiO 3-BaTiO 3-K 0.5Na 0.5NbO 3 thick films

    Science.gov (United States)

    Fu, Fang; Zhai, Jiwei; Xu, Zhengkui; Bai, Wangfeng; Yao, Xi

    2011-05-01

    Textured (1 - x)(0.94Na 0.5Bi 0.5TiO 3 - 0.06BaTiO 3) - xK 0.5Na 0.5NbO 3 (abbreviated as NBT-BT-KNN) thick film on platinum substrate was prepared via tape casting method. The structure and electrical properties of the thick films were investigated. The results show that the thick films possess typical polycrystalline perovskite structures and the orientation degree reached to 75%. The remnant polarization ( Pr) and coercive field ( Ec) were optimized to 11.2 μC/cm 2 and 12.8 kV/cm for x = 0.02 thick film. The dielectric properties of NBT-BT-KNN thick films as a function of temperature were also investigated. With the addition of KNN, the Td (depolarization temperature) and TC (Curie temperature) are all decreased. Meanwhile, the dielectric constant is increased with the addition of the KNN at room temperature. The piezoelectric constant of the thick film was calculated from unipolar electric field-induced strain curve. With the addition of KNN, the d33 value increased and reached to the maximum value of 349 pm/V for x = 0.02 thick film.

  6. Variability of soil moisture and its relationship with surface albedo and soil thermal diffusivity at Astronomical Observatory, Thiruvananthapuram, south Kerala

    Indian Academy of Sciences (India)

    M S Roxy; V B Sumithranand; G Renuka

    2010-08-01

    Continuous observation data collected over the year 2008 at Astronomical Observatory, Thiruvananthapuram in south Kerala (76° 59′E longitude and 8° 30′N latitude) are used to study the diurnal, monthly and seasonal soil moisture variations. The effect of rainfall on diurnal and seasonal soil moisture is discussed. We have investigated relationships of soil moisture with surface albedo and soil thermal diffusivity. The diurnal variation of surface albedo appears as a U-shaped curve on sunny days. Surface albedo decreases with the increase of solar elevation angle, and it tends to be a constant when solar elevation angle is greater than 40°. So the daily average surface albedo was calculated using the data when solar elevation angle is greater than 40°. The results indicate that the mean daily surface albedo decreases with increases in soil moisture content, showing a typical exponential relation between the surface albedo and the soil moisture. Soil thermal diffusivity increases firstly and then decreases with the increase of soil moisture.

  7. Heavy Metal Pollution of Surface Soil in Thrace Region (Turkey)

    CERN Document Server

    Cocskun, M; Frontasyeva, M V; Munevver, C; Eidhammer Sjobakk, T; Demkina, S V

    2004-01-01

    Samples of surface soil were collected at 73 sites in the Thrace region, northwest part of Turkey. Two complementary analytical techniques, epithermal neutron activation analysis (ENAA) and atomic absorption spectrometry (AAS) with flame and graphite furnace atomization were used to determine 37 elements in the soil samples. Concentrations of Cu, Zn, Ni, Cd, Mn, Co, Pb, and As were determined using AAS and GF AAS and ENAA was used for the remaining 29 elements. Results for As, Ba, Br, Ca, Cd, Ce, Cr, Cs, Eu, Fe, Hf, I, In, K, La, Mn, Mo, Na, Nd, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, Ti, U, and V are reported for the first time for soils from this region. The results show that concentrations of the most elements were little affected by the industrial and other anthropogenic activities performed in the region. Except for distinctly higher levels of Pb, Cu, Cd, and Zn in Istanbul district than the median values for the Thrace region, the observed distributions seem to be mainly associated with lithogenic variations. S...

  8. Radiation hardness of Ga0.5In0.5 P/GaAs tandem solar cells

    Science.gov (United States)

    Kurtz, Sarah R.; Olson, J. M.; Bertness, K. A.; Friedman, D. J.; Kibbler, A.; Cavicchi, B. T.; Krut, D. D.

    1991-01-01

    The radiation hardness of a two-junction monolithic Ga sub 0.5 In sub 0.5 P/GaAs cell with tunnel junction interconnect was investigated. Related single junction cells were also studied to identify the origins of the radiation losses. The optimal design of the cell is discussed. The air mass efficiency of an optimized tandem cell after irradiation with 10(exp 15) cm (-2) 1 MeV electrons is estimated to be 20 percent using currently available technology.

  9. Magnetic properties of Nd0.5Pb0.5-xSrxMnO3 materials

    Institute of Scientific and Technical Information of China (English)

    鲁毅; 李庆安; 邸乃力; 马骁; 寇志起; 罗志; 成昭华

    2003-01-01

    The structure and magnetic properties of Nd0.5Pb0.5-xSrxMnO3 (0 ≤ x ≤0.4) manganites were systematicallyinvestigated. Significant changes in Curie temperature and metal-insulator (MI) transition temperature of the sampleswere observed. All samples exhibited a transition from paramagnetic semiconducting to ferromagnetic metallic state.Curie temperature TC and the MI transition temperature Tp increased with increasing Sr content. We attributed thesebehaviours to the enhancing of both the double exchange mechanism and the Jahn-Teller electron-phonon coupling.

  10. Ab initio study of ferromagnetic La0.5Ba0.5CoO3

    Indian Academy of Sciences (India)

    Umesh V Waghmare

    2003-10-01

    We study structure and magnetic properties of La0.5Ba0.5CoO3 (LBCO) using ab initio density functional theory (DFT) method based on pseudopotentials and a plane-wave basis. We find the cubic structure of LBCO is ferromagnetic and lower in energy than the nonmagnetic rhombohedral structure. Through the calculation of -point phonons of LBCO in the cubic structure, we determine its structural instabilities and find that they correspond to the structural phase transition accompanying a para-ferromagnetic transition observed recently.

  11. Kinetic study of wet oxidation of Si0.5Ge0.5 alloy by Rutherford backscattering spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidation of Si0. sGeo.5 alloy has been investigated at the temperatures of 800℃ and 900 ℃. Rutherford backscattering spectroscopy has been employed to determine the composition and thickness of the oxide layers. Only Sio.5Geo. 5O2 layer formed during the oxidation at 800℃, whilst three layers, Si0.5Ge0.5O2, SiO2 and Ge, are existed after the oxidation at 900℃. Experimental results are interpreted by adding a germanium flux F4 in Deal-Grove oxidation model of Silicon.

  12. Estimation of Joule heating and its role in nonlinear electrical response of Tb0.5Sr0.5MnO3 single crystal

    Science.gov (United States)

    Nhalil, Hariharan; Elizabeth, Suja

    2016-12-01

    Highly non-linear I-V characteristics and apparent colossal electro-resistance were observed in non-charge ordered manganite Tb0.5Sr0.5MnO3 single crystal in low temperature transport measurements. Significant changes were noticed in top surface temperature of the sample as compared to its base while passing current at low temperature. By analyzing these variations, we realize that the change in surface temperature (ΔTsur) is too small to have caused by the strong negative differential resistance. A more accurate estimation of change in the sample temperature was made by back-calculating the sample temperature from the temperature variation of resistance (R-T) data (ΔTcal), which was found to be higher than ΔTsur. This result indicates that there are large thermal gradients across the sample. The experimentally derived ΔTcal is validated with the help of a simple theoretical model and estimation of Joule heating. Pulse measurements realize substantial reduction in Joule heating. With decrease in sample thickness, Joule heating effect is found to be reduced. Our studies reveal that Joule heating plays a major role in the nonlinear electrical response of Tb0.5Sr0.5MnO3. By careful management of the duty cycle and pulse current I-V measurements, Joule heating can be mitigated to a large extent.

  13. Effects of oxygen defects on structure and properties of Sm0.5Sr0.5CoO3-δannealed in different atmospheres

    Institute of Scientific and Technical Information of China (English)

    陆依; 陈乐; 陆春华; 倪亚茹; 许仲梓

    2013-01-01

    Samples of Sm0.5Sr0.5CoO3-δwere annealed in different atmospheres (Ar, N2, and O2) and temperatures (400-1200 ºC), and changes in their masses, structures, surface transport properties, optical properties, and oxygen nonstoichiometries were investi-gated using thermogravimetric (TG) analyses, X-ray diffraction (XRD) analyses, electrical conductivity measurements, reflection spectra measurements, and X-ray photoelectron spectroscopy, respectively. The TG analyses, performed in air and an N2 atmosphere, allowed us to determine the changes in the masses of the samples. The results of the XRD analyses elucidated the changes in the structure of the samples under different conditions. The XPS spectra and simulation data indicated that the number of oxygen defects generated in the samples depended on the temperature and atmosphere. At high temperatures, the surface conductivities and full-spectrum reflectivities of the samples decreased with an increase in the number of oxygen vacancies. In an oxidative atmosphere, the samples exhibited outstanding visible and near-infrared light absorption. Furthermore, the samples were highly sensitive to a re-ducing atmosphere at various temperatures. On the basis of the fact that the properties of Sm0.5Sr0.5CoO3-δvary with the environment, it has potential use in high-temperature applications such as weather sensors.

  14. Soil Specific Surface Area and Non-Singularity of Soil-Water Retention at Low Saturations

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per

    2013-01-01

    and Or (TO) and new single-parameter non-singularity (SPN) models; and evaluate estimates of SSA from water sorption, ethylene glycol monoethyl ether (EGME), and N2–BET methods. The AquaSorp successfully measured water sorption isotherms (∼140 data points) within a reasonably short time (1–3 d). The SPN......The dry end of the soil water characteristic (SWC) is important for modeling vapor flow dynamics and predicting soil properties such as specific surface area (SSA) and clay content (CL). Verification of new instrumentation for rapid measurement of the dry end of the SWC is relevant to avoid long...... model well described the distinct non-singularity between the adsorption and desorption branches, while the TO model captured the adsorption data reasonably well (model were...

  15. Effects of soil heterogeneity on steady state soil water pressure head under a surface line source

    Science.gov (United States)

    Zhang, Z. Fred; Parkin, Gary W.; Kachanoski, R. Gary; Smith, James E.

    2002-07-01

    There are numerous analytical solutions available for flow in unsaturated homogeneous porous media. In this paper, the stream tube model for one-dimensional water movement is extended to two-dimensional (2-D) water movement from a line source as the stream plane model. As well, new solutions are derived to predict the mean and variance of pressure head of water movement under a surface line source in heterogeneous soil using the perturbation method with first-order approximation (PM1) and with second-order approximation (PM2). A variance expression was also developed based on the spectral relationship presented by Yeh et al. [1985a]. The new solutions were tested using the 2-D stream plane model with parameters A = ln(α) and Y = ln(KS) and measurements from field experiments. Results show that the mean of steady state pressure head below the line source is not only a function of the mean parameter values but also a function of the variances of A and Y and the linear cross-correlation coefficient (ρ) between A and Y. The PM2 model can predict the mean pressure head accurately in heterogeneous soils at any level of correlation between A and Y, except when both the soil variability and ρ are high. The pressure head variance estimation based on the PM1 model predicts the measured variance well only when both the soil variability and ρ are low. The field experimental results show that both the PM1 and the spectral models give reasonable predictions of the pressure head variance. Both the measured and predicted values of the variance of pressure head using the two models increase with the depth of soil. Both models show that the variance of pressure head decreases as the source strength increases, but on average, the pressure head variance was underestimated by both models.

  16. Nanostructural and electrical properties of LA0.5SR0.5CoO3

    Science.gov (United States)

    Bahari, A.; Ramzannezhad, A.; Shajari, D.; Najafi, H.

    2017-02-01

    A group of ABO3 perovskite-type oxides is currently under intensive studies for their potential as chemical sensing, ferroelectric memories, gas separation and computer devices. This group includes LaxSr1‑xCoO3 (LSCO). In the present work, we have synthesized LSCO samples by using the sol-gel method and studied their nano structural and electrical properties with using the scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Current density-voltage (J-V) and Fourier transform infrared spectroscopy (FTIR) techniques. We synthesized nanoparticles with diameters between 50 and 100 nm by calcination of the pulverized gel powders, and then studied its structure. The band gap characteristics of the La0.5Sr0.5CoO3 structure were also analyzed. The obtained results show that La0.5Sr0.5CoO3 with favorable carrier mobility ( ˜ 1.7 × 10‑2 cm2v‑2s‑1) and dielectric constant (16) exhibits a variety of interesting physical properties which include ferroelectric, dielectric, pyroelectric and piezoelectric behavior.

  17. Negative Thermal Expansion in Ba0.5Sr0.5Zn₂SiGeO₇.

    Science.gov (United States)

    Thieme, Christian; Rüssel, Christian

    2016-07-27

    Solid solutions with the composition Ba0.5Sr0.5Zn₂Si2-xGexO₇ and BaZn₂Si2-xGexO₇ were prepared with different values of x using a conventional mixed oxide route. Both compounds exhibit very different thermal expansion, which is due to the different crystal structures. Ba0.5Sr0.5Zn₂Si2-xGexO₇ solid solutions exhibit the structure of high-temperature BaZn₂Si₂O₇ and show negative thermal expansion, which was proven via high-temperature X-ray diffraction. Up to around x = 1, the crystal structure remains the same. Above this value, the low-temperature phase becomes stable. The Sr-free solid solutions have the crystal structure of low-temperature BaZn₂Si₂O₇ and show also a limited solubility of Ge. These Sr-free compositions show transitions of low- to high-temperature phases, which are shifted to higher temperatures with increasing Ge-concentration.

  18. Negative Thermal Expansion in Ba0.5Sr0.5Zn2SiGeO7

    Science.gov (United States)

    Thieme, Christian; Rüssel, Christian

    2016-01-01

    Solid solutions with the composition Ba0.5Sr0.5Zn2Si2-xGexO7 and BaZn2Si2-xGexO7 were prepared with different values of x using a conventional mixed oxide route. Both compounds exhibit very different thermal expansion, which is due to the different crystal structures. Ba0.5Sr0.5Zn2Si2-xGexO7 solid solutions exhibit the structure of high-temperature BaZn2Si2O7 and show negative thermal expansion, which was proven via high-temperature X-ray diffraction. Up to around x = 1, the crystal structure remains the same. Above this value, the low-temperature phase becomes stable. The Sr-free solid solutions have the crystal structure of low-temperature BaZn2Si2O7 and show also a limited solubility of Ge. These Sr-free compositions show transitions of low- to high-temperature phases, which are shifted to higher temperatures with increasing Ge-concentration. PMID:28773746

  19. A CLINICAL COMPARISON OF COMPOUNDED SOLUTION (2% XYLOCAINE & 0.5% BUPIVACAINE WITH 0.5% BUPIVACAINE IN EPIDURAL ANALGESIA

    Directory of Open Access Journals (Sweden)

    Sathesha

    2014-09-01

    Full Text Available Epidural Analgesia is used for relief of pain during and following surgical operations, for relief of chronic pain, for relief of pain in labour, reduction of bleeding by producing sympathetic blockade and hypotension during surgery or to supplement light general anaesthesia, thereby suppressing the transmission of afferent impulses and autonomic and hormonal response to surgery. The commonly used drugs for epidural analgesia are 2% xylocaine and 0.5% bupivacaine. Mixing of the local anaesthetics and altering the pH have been found to be safe and cost effective.1,2 our study was a prospective randomized controlled double blind study to investigate effect of the benefits of usage of a compounded solution (2% xylocaine and 0.5% bupivacaine in a 1:1 ratio over a single drug (0.5% bupivacaine and ascertain whether it can be recommended for routine use in epidural analgesia in regular anaesthetic practice.3,4,5 The following parameters are Studied 1 The time of onset of analgesia. 2 The quality of analgesia. 3 The degree of motor blockade. 4 Duration of analgesia. 5 Safety of compounding local anaesthetics. METHODS AND MATERIAL: One Hundred Adult Patients of either sex ranging between 20-60 years of age belonging to ASA grade 1 and II were studied. All patients were at random divided into 2 groups fifty in each group. Group A received 0.5% bupivacaine 15cc. Group B received a mixture of 0.5% bupivacine and 2% xylocaine (7.5cc + 7.5cc RESULTS: Mean time of onset of analgesia in group B was lower (11.50 + 2.05 as compared to group A (22.24 + 2.18 and this difference was statistically highly significant (P<0.001. 16% of group A and 6% of group B required to be changed over to general anaesthesia. Grade IV motor blockade was seen only in 24% of group A and 30% of the group B which is significant. Mean duration of action in group A was higher (128.90 + 6.70 than in group B (98.30 + 5.29 and this difference was statistically significant. CONCLUSIONS: The

  20. Uranium partition coefficients (Kd) in forest surface soil reveal long equilibrium times and vary by site and soil size fraction.

    Science.gov (United States)

    Whicker, Jeffrey J; Pinder, John E; Ibrahim, Shawki A; Stone, James M; Breshears, David D; Baker, Kristine N

    2007-07-01

    The environmental mobility of newly deposited radionuclides in surface soil is driven by complex biogeochemical relationships, which have significant impacts on transport pathways. The partition coefficient (Kd) is useful for characterizing the soil-solution exchange kinetics and is an important factor for predicting relative amounts of a radionuclide transported to groundwater compared to that remaining on soil surfaces and thus available for transport through erosion processes. Measurements of Kd for 238U are particularly useful because of the extensive use of 238U in military applications and associated testing, such as done at Los Alamos National Laboratory (LANL). Site-specific measurements of Kd for 238U are needed because Kd is highly dependent on local soil conditions and also on the fine soil fraction because 238U concentrates onto smaller soil particles, such as clays and soil organic material, which are most susceptible to wind erosion and contribute to inhalation exposure in off-site populations. We measured Kd for uranium in soils from two neighboring semiarid forest sites at LANL using a U.S. Environmental Protection Agency (EPA)-based protocol for both whole soil and the fine soil fraction (diametersKd values, which are those specified in the EPA protocol, ranged from 276-508 mL g-1 for whole soil and from 615-2249 mL g-1 for the fine soil fraction. Unexpectedly, the 30-d Kd values, measured to test for soil-solution exchange equilibrium, were more than two times the 7-d values. Rates of adsorption of 238U to soil from solution were derived using a 2-component (FAST and SLOW) exponential model. We found significant differences in Kd values among LANL sampling sites, between whole and fine soils, and between 7-d and 30-d Kd measurements. The significant variation in soil-solution exchange kinetics among the soils and soil sizes promotes the use of site-specific data for estimates of environmental transport rates and suggests possible differences in

  1. Structural state of relaxor ferroelectrics PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 at high pressures up to 30 GPa

    Science.gov (United States)

    Maier, B. J.; Waeselmann, N.; Mihailova, B.; Angel, R. J.; Ederer, C.; Paulmann, C.; Gospodinov, M.; Friedrich, A.; Bismayer, U.

    2011-11-01

    The pressure-induced structural changes in perovskite-type (ABO3) Pb-based relaxor ferroelectrics are studied on the basis of in situ single-crystal synchrotron x-ray diffraction and Raman scattering experiments on PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 conducted under hydrostatic conditions up to 30 GPa. Complementary density functional theory calculations have been performed to compare the stability of various atomic configurations for both compounds at high pressures. By combining the experimental and theoretical results, the following sequence of structural transformations is proposed. At a characteristic pressure p1 the mesoscopic polar order is violated and a local antipolar order of Pb atoms as well as quasidynamical long-range order of antiphase octahedral tilts is developed. These structural changes facilitate the occurrence of a continuous phase transition at pc1>p1 from cubic to a nonpolar rhombohedral structure comprising antiphase octahedral tilts of equal magnitude (a-a-a-). At a characteristic pressure p2>pc1 the octahedral tilts around the cubic [100], [010], and [001] directions become different from each other on the mesoscopic scale. The latter precedes a second phase transition at pc2, which involves long-range order of Pb antipolar displacements along cubic [uv0] directions and a compatible mixed tilt system (a+b-b-) or long-range ordered antiphase tilts with unequal magnitudes (a0b-b-) without Pb displacement ordering. The phase-transition pattern at pc2 depends on the fine-scale degree of chemical B-site order in the structure.

  2. SHAKER Version 0.0/5 Pre-release Notes

    CERN Document Server

    CERN. Geneva

    1993-01-01

    SHAKER V0.0/5 is a pre-release of a simple cocktail central rapidity phase space event generator developed for the simulation of LHC Heavy Ion events. A modified version of JETSET 7.3 (the / LUJETS / common has been enlarged to 50000 particles and the LUEDIT routine has been modified to rearrange the particle weights vectors when called with MEDIT=1) is used to manage the events. All event information is included in / LUJETS / according to Lund conventions [1].

  3. Effects of soil surface roughness on interrill erosion processes and sediment particle size distribution

    Science.gov (United States)

    Ding, Wenfeng; Huang, Chihua

    2017-10-01

    Soil surface roughness significantly impacts runoff and erosion under rainfall. Few previous studies on runoff generation focused on the effects of soil surface roughness on the sediment particle size distribution (PSD), which greatly affects interrill erosion and sedimentation processes. To address this issue, a rainfall-simulation experiment was conducted with treatments that included two different initial soil surface roughnesses and two rainfall intensities. Soil surface roughness was determined by using photogrammetric method. For each simulated event, runoff and sediment samples were collected at different experimental times. The effective (undispersed) PSD of each sediment sample and the ultimate (after dispersion) PSD were used to investigate the detachment and transport mechanisms involved in sediment movement. The results show that soil surface roughness significantly delayed runoff initiation, but had no significant effect on the steady runoff rate. However, a significant difference in the soil loss rate was observed between the smooth and rough soil surfaces. Sediments from smooth soil surfaces were more depleted in clay-size particles, but more enriched in sand-size particles than those from rough soil surfaces, suggesting that erosion was less selective on smooth than on rough soil surfaces. The ratio of different sizes of transported sediment to the soil matrix indicates that most of the clay was eroded in the form of aggregates, silt-size particles were transported mainly as primary particles, and sand-size particles were predominantly aggregates of finer particles. Soil surface roughness has a crucial effect on the sediment size distribution and erosion processes. Significant differences of the enrichment ratios for the effective PSD and the ultimate PSD were observed under the two soil surface roughness treatments. These findings demonstrate that we should consider each particle size separately rather than use only the total sediment discharge in

  4. Soil surface morphology evolution under spatiallynon-uniform rainfall

    Science.gov (United States)

    Cheraghi, M.; Rinaldo, A.; Sander, G. C.; Barry, D. A.

    2016-12-01

    We evaluated the applicability of a large-scale river network evolution modelused to simulate morphological changes of a laboratory-scale landscape onwhich there were no visible rills. Previously, such models were used onlyat the landscape scale, or in laboratory experiments where rills form in thesoils surface. The flume-scale experiment (1-m × 2-m surface area) was de-signed to allow model calibration. Low-cohesive fine sand was placed in theflume while the slope and relief height were 5% and 25 cm, respectively.Non-uniform rainfall with an average intensity of 85 mmh -1 and a stan-dard deviation of 26% was applied to the sediment surface for 16 h. Highresolution Digital Elevation Models were captured at intervals during theexperiment. Estimates of the overland flow drainage network were derivedand, using these, the river network evolution model was numerically solvedand calibrated. A noticeable feature of the experiment was a steep transitionzone in soil elevation that migrated upstream during the experiment. Physi-cally, this zone indicates where the shear stress is sufficient to cause sediment1erosion. The model was calibrated during the first 4 h of experiment. Af-terwards, it predicted the subsequent 12 h of measured surface morphologychanges. Therefore, the applicability of the landscape evolution model wasextended for non-uniform rainfall and in absence of visible rills.Keywords:Numerical simulation, Particle Swarm Optimization, Sediment transport,River network evolution model.

  5. Coupling of Spin and Orbital Excitations in the Iron-based Superconductor FeSe0.5Te0.5

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.H.; Xu, G.; Ku, W.; Wen, J.S.; Lee, C.C.: Katayama, N.; Xu, Z.J.; Ji, S.; Lin, Z.W.; Gu, G. D.; Yang, H.-B.; Johnson, P.D.; Pan, Z.-H.; Valla, T.; Fujita, M.; Sato, T.J.; Chang, S.; Yamada, K.; Tranquada, J.M.

    2010-06-14

    We present a combined analysis of neutron scattering and photoemission measurements on superconducting FeSe{sub 0.5}Te{sub 0.5}. The low-energy magnetic excitations disperse only in the direction transverse to the characteristic wave vector (1/2,0,0) whereas the electronic Fermi surface near (1/2,0,0) appears to consist of four incommensurate pockets. While the spin resonance occurs at an incommensurate wave vector compatible with nesting, neither spin-wave nor Fermi-surface-nesting models can describe the magnetic dispersion. We propose that a coupling of spin and orbital correlations is key to explaining this behavior. If correct, it follows that these nematic fluctuations are involved in the resonance and could be relevant to the pairing mechanism.

  6. Coupling of spin and orbital excitations in the iron-based superconductor FeSe0.5Te0.5

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.-H.; Xu, Guangyong; Ku, Wei; Wen, J.S.; Lee, C.C.; Katayama, N.; Xu, Z.J.; Ji, S.; Lin, Z.W.; Gu, G.D.; Yang, H.-B.; Johnson, Peter D.; Pan, Z.-H.; Valla, Tonica; Fujita, M.; Sato, T.J.; Chang, S.; Yamada, K.; Tranquada, John M.

    2010-06-14

    We present a combined analysis of neutron scattering and photoemission measurements on superconducting FeSe{sub 0.5} Te{sub 0.5} . The low-energy magnetic excitations disperse only in the direction transverse to the characteristic wave vector (1/2 ,0,0) whereas the electronic Fermi surface near (1/2 ,0,0) appears to consist of four incommensurate pockets. While the spin resonance occurs at an incommensurate wave vector compatible with nesting, neither spin-wave nor Fermi-surface-nesting models can describe the magnetic dispersion. We propose that a coupling of spin and orbital correlations is key to explaining this behavior. If correct, it follows that these nematic fluctuations are involved in the resonance and could be relevant to the pairing mechanism.

  7. Strain profile and polarization enhancement in Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Amir, F.Z. [Physics Department, St John' s University, 8000 Utopia Pkwy, Jamaica, NY 11439 (United States); Donner, W. [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Aspelmeyer, M. [Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Noheda, B. [Department of Chemical Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Xi, X.X. [Physics Department, College of Science and Technology, Temple University, 1900 N.13th Street, Philadelphia, PA 19122 (United States); Moss, S.C. [Department of Physics, University of Houston, 617 Science and Research Building 1, Houston, Texas 77204-5005 (United States)

    2012-11-15

    The sensitivity of spontaneous polarization to epitaxial strain for both 10 and 50 nm thick Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BSTO) ferroelectric thin films has been studied. Crystal truncation rod (CTR) profiles in the 00L directions at different wavelengths, and grazing incidence diffraction (GID) in the 0K0 direction on a single crystal have been recorded. Modeling of the CTR data gives a detailed picture of the strain and provides clear evidence of the film out-of-plane expansion at the surface, an increase of the polarization, as well as a contraction at the interface. GID data confirm the fitting of the CTR, showing an in-plane expansion of the BSTO film at the interface and a contraction at the surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Li diffusion in LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} thin film electrodes prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xia Hui [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore); Lu Li [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)], E-mail: mpeluli@nus.edu.sg; Lai, M.O. [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2009-10-30

    Kinetic and transport parameters of Li ion during its extraction/insertion into thin film LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} free of binder and conductive additive were provided in this work. LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} thin film electrodes were grown on Au substrates by pulsed laser deposition (PLD) and post-annealed. The annealed films exhibit a pure layered phase with a high degree of crystallinity. Surface morphology and thin film thickness were investigated by field emission scanning electron microscopy (FESEM). The charge/discharge behavior and rate capability of the thin film electrodes were investigated on Li/LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} cells at different current densities. The kinetics of Li diffusion in these thin film electrodes were investigated by cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT). CV was measured between 2.5 and 4.5 V at different scan rates from 0.1 to 2 mV/s. The apparent chemical diffusion coefficients of Li in the thin film electrode were calculated to be 3.13 x 10{sup -13} cm{sup 2}/s for Li intercalation and 7.44 x 10{sup -14} cm{sup 2}/s for Li deintercalation. The chemical diffusion coefficients of Li in the thin film electrode were determined to be in the range of 10{sup -12}-10{sup -16} cm{sup 2}/s at different cell potentials by GITT. It is found that the Li diffusivity is highly dependent on the cell potential.

  9. Soil hydraulic parameters and surface soil moisture of a tilled bare soil plot inversely derived from l-band brightness temperatures

    KAUST Repository

    Dimitrov, Marin

    2014-01-01

    We coupled a radiative transfer model and a soil hydrologic model (HYDRUS 1D) with an optimization routine to derive soil hydraulic parameters, surface roughness, and soil moisture of a tilled bare soil plot using measured brightness temperatures at 1.4 GHz (L-band), rainfall, and potential soil evaporation. The robustness of the approach was evaluated using five 28-d data sets representing different meteorological conditions. We considered two soil hydraulic property models: the unimodal Mualem-van Genuchten and the bimodal model of Durner. Microwave radiative transfer was modeled by three different approaches: the Fresnel equation with depth-averaged dielectric permittivity of either 2-or 5-cm-thick surface layers and a coherent radiative transfer model (CRTM) that accounts for vertical gradients in dielectric permittivity. Brightness temperatures simulated by the CRTM and the 2-cm-layer Fresnel model fitted well to the measured ones. L-band brightness temperatures are therefore related to the dielectric permittivity and soil moisture in a 2-cm-thick surface layer. The surface roughness parameter that was derived from brightness temperatures using inverse modeling was similar to direct estimates from laser profiler measurements. The laboratory-derived water retention curve was bimodal and could be retrieved consistently for the different periods from brightness temperatures using inverse modeling. A unimodal soil hydraulic property function underestimated the hydraulic conductivity near saturation. Surface soil moisture contents simulated using retrieved soil hydraulic parameters were compared with in situ measurements. Depth-specific calibration relations were essential to derive soil moisture from near-surface installed sensors. © Soil Science Society of America 5585 Guilford Rd., Madison, WI 53711 USA.

  10. Effects of Carrier on CuO/TiO2 and CuO/Ti0.5Zr0.5O2 Catalysts in the NO+CO Reaction

    Institute of Scientific and Technical Information of China (English)

    Guang Hui DING; Xiao Yuan JIANG; Xiao Ming ZHENG

    2005-01-01

    Using TiO2 and Ti0.5Zr0.5O2 as carriers, the CuO/TiO2 and CuO/Ti0.5Zr0.5O2 catalysts were prepared by the impregnation method with Gu(NO3)2 as active component. The catalytic activities in NO+CO reaction were investigated using a microreactor-GC system, and structure and reducibility of catalysts were characterized by means of physical adsorption, TPR, XRD, NO-TPD technologies. It was found that the activity of CuO/Ti0.5Zr0.5O2 catalyst was higher than that of CuO/TiO2, probably due to the large specific surface area of Ti0.5Zr0.5O2 that played an important role in NO+CO reaction.

  11. Permafrost temperature and active-layer thickness of Yakutia with 0.5 degree spatial resolution for model evaluation

    Directory of Open Access Journals (Sweden)

    C. Beer

    2013-05-01

    Full Text Available Based on the map of landscapes and permafrost conditions in Yakutia (Merzlotno-landshaftnaya karta Yakutskoi0 ASSR, Gosgeodeziya SSSR, 1991, rasterized maps of permafrost temperature and active-layer thickness of Yakutia, East Siberia were derived. The mean and standard deviation at 0.5 degree grid cell size are estimated by assigning a probability density function at 0.001 degree spatial resolution. The gridded datasets can be accessed at the PANGAEA repository (doi:10.1594/PANGAEA.808240. Spatial pattern of both variables are dominated by a climatic gradient from north to south, and by mountains and the soil type distribution. Uncertainties are highest in mountains and in the isolated permafrost zone in the south. The maps are best suited as a benchmark for land surface models which include a permafrost module.

  12. Permafrost temperature and active-layer thickness of Yakutia with 0.5-degree spatial resolution for model evaluation

    Science.gov (United States)

    Beer, C.; Fedorov, A. N.; Torgovkin, Y.

    2013-09-01

    Based on the map of landscapes and permafrost conditions in Yakutia (Merzlotno-landshaftnaya karta Yakutskoi0 ASSR, Gosgeodeziya SSSR, 1991), rasterized maps of permafrost temperature and active-layer thickness of Yakutia, East Siberia were derived. The mean and standard deviation at 0.5-degree grid cell size are estimated by assigning a probability density function at 0.001-degree spatial resolution. The gridded datasets can be accessed at the PANGAEA repository (doi:10.1594/PANGAEA.808240). Spatial pattern of both variables are dominated by a climatic gradient from north to south, and by mountains and the soil type distribution. Uncertainties are highest in mountains and in the sporadic permafrost zone in the south. The maps are best suited as a benchmark for land surface models which include a permafrost module.

  13. Intra-rainfall soil surface change detection using close-range photogrammetry

    Science.gov (United States)

    Bauer, Thomas; James, Michael R.; McShane, Gareth; Quinton, John N.; Strauss, Peter

    2015-04-01

    During precipitation events, the physical properties of soil surfaces change significantly. Such changes influence a large range of processes, e.g. surface runoff, soil erosion, water infiltration, soil-atmosphere interactions and plant growth. It has been proven that successive precipitation events change soil surfaces, but detailed studies on soil surface change within a single rainfall event do, to the best of our knowledge, not exist, due to a lack of suitable methods. However, recent developments in the use of photogrammetry are becoming a common tool in geoscience and can be utilized in soil surface detection. New concepts, developments in hardware and software allow a quick and user friendly calculation of surface models with close-range imagery and processing based on structure from motion (SfM) approaches. In this study we tested the potential of close range photogrammetry for detecting changes in soil surface topography within an artificial rainfall event. We used a photogrammetric approach to capture multiple images of the soil surface on two different soil types (loamy and sandy soil) under laboratory conditions while they were exposed to a 60 minute duration 47(60) mm hr-1 intensity rainfall event from a gravity driven rainfall simulator. The photographs were processed using Photoscan to produce point clouds which were then interpolated to produce DEM surfaces. Of the 126 surfaces produced during the rainfall event 125 were usable and able to demonstrate changes with a resolution of photogrammetry for surface detection within a precipitation event. The use of close-range photogrammetry opens new possibilities to monitor soil surfaces and could be developed for a range of other applications. Our results have the potential to lead to better understanding of infiltration, runoff, nutrient transport and soil erosion processes within precipitation event.

  14. On the soil roughness parameterization problem in soil moisture retrieval of bare surfaces from Synthetic Aperture Radar 1959

    Science.gov (United States)

    Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unles...

  15. Above- and below-ground responses of four tundra plant functional types to deep soil heating and surface soil fertilization

    NARCIS (Netherlands)

    Wang, Peng; Limpens, Juul; Mommer, Liesje; Ruijven, van Jasper; Nauta, Ake L.; Berendse, Frank; Schaepman-Strub, Gabriela; Blok, Daan; Maximov, Trofim C.; Heijmans, Monique M.P.D.

    2017-01-01

    Climate warming is faster in the Arctic than the global average. Nutrient availability in the tundra soil is expected to increase by climate warming through (i) accelerated nutrient mobilization in the surface soil layers, and (ii) increased thawing depths during the growing season which

  16. Effects of Near Soil Surface Characteristics on the Soil Detachment Process in a Chronological Series of Vegetation Restoration

    Science.gov (United States)

    Wang, Bing

    2017-04-01

    The effects of near soil surface characteristics on the soil detachment process might be different at different stages of vegetation restoration. This study was performed to investigate the effects of the near soil surface factors of plant litter, biological soil crusts (BSCs), dead roots and live roots on the soil detachment process by overland flow at different stages of restoration. Soil samples (1 m long, 0.1 m wide, and 0.05 m high) under four treatment conditions were collected from 1-yr-old and 24-yr-old natural grasslands and subjected to flow scouring under five different shear stresses ranging from 5.3 to 14.6 Pa. The results indicated that the effects of near soil surface characteristics on soil detachment were substantial during the process of vegetation restoration. The total reduction in the soil detachment capacity of the 1-yr-old grassland was 98.1%, and of this total, 7.9%, 30.0% and 60.2% was attributed to the litter, BSCs and plant roots, respectively. In the 24-yr-old grassland, the soil detachment capacity decreased by 99.0%, of which 13.2%, 23.5% and 62.3% was caused by the litter, BSCs and plant roots, respectively. Combined with the previously published data of a 7-yr-old grassland, the influence of plant litter on soil detachment was demonstrated to increase with restoration time, but soil detachment was also affected by the litter type and composition. The role of BSCs was greater than that of plant litter in reducing soil detachment during the early stages of vegetation recovery. However, its contribution weakened with time since restoration. The influence of plant roots accounted for at least half or up to two-thirds of the total near soil surface factors, of which more than 72.6% was attributed to the physical binding effects of the roots. The chemical bonding effect of the roots increased with time since restoration and was greater than the effect of the litter on soil detachment in the late stages of vegetation restoration. The

  17. Characterization Investigation Study: Volume 3, Radiological survey of surface soils

    Energy Technology Data Exchange (ETDEWEB)

    Solow, A.J.; Phoenix, D.R.

    1987-12-01

    The Feed Materials Production Center was constructed to produce high purity uranium metal for use at various Department of Energy facilities. The waste products from these operations include general uncontaminated scrap and refuse, contaminated and uncontaminated metal scrap, waste oils, low-level radioactive waste, co-contaminated wastes, mixed waste, toxic waste, sludges from water treatment, and fly ash from the steam plant. This material is estimated to total more than 350,000 cubic meters. Other wastes stored in this area include laboratory chemicals and other combustible materials in the burn pit; fine waste stream sediments in the clear well; fly ash and waste oils in the two fly ash areas; lime-alum sludges and boiler plant blowdown in the lime sludge ponds; and nonradioactive sanitary waste, construction rubble, and asbestos in the sanitary landfill. A systematic survey of the surface soils throughout the Waste Storage Area, associated on-site drainages, and the fly ash piles was conducted using a Field Instrument for Detecting Low-Energy Radiation (FIDLER). Uranium is the most prevalent radioactive element in surface soil; U-238 is the principal radionuclide, ranging from 2.2 to 1790 pCi/g in the general Waste Storage Area. The maximum values for the next highest activity concentrations in the same area were 972 pCi/g for Th-230 and 298 pCi/g for U-234. Elevated activity concentrations of Th-230 were found along the K-65 slurry line, the maximum at 3010 pCi/g. U-238 had the highest value of 761 pCi/g in the drainage just south of pit no. 5. The upper fly ash area had the highest radionuclide activity concentrations in the surface soils with the maximum values for U-238 at 8600 pCi/g, U-235 at 2190 pCi/g, U-234 at 11,400 pCi/g, Tc-99 at 594 pCi/g, Ra-226 at 279 pCi/g, and Th-230 at 164 pCi/g.

  18. Ferroelectricity and ferroelectric resistive switching in sputtered Hf0.5Zr0.5O2 thin films

    Science.gov (United States)

    Fan, Zhen; Xiao, Juanxiu; Wang, Jingxian; Zhang, Lei; Deng, Jinyu; Liu, Ziyan; Dong, Zhili; Wang, John; Chen, Jingsheng

    2016-06-01

    Ferroelectric properties and ferroelectric resistive switching (FE-RS) of sputtered Hf0.5Zr0.5O2 (HZO) thin films were investigated. The HZO films with the orthorhombic phase were obtained without capping or post-deposition annealing. Ferroelectricity was demonstrated by polarization-voltage (P-V) hysteresis loops measured in a positive-up negative-down manner and piezoresponse force microscopy. However, defects such as oxygen vacancies caused the films to become leaky. The observed ferroelectricity and semiconducting characteristics led to the FE-RS effect. The FE-RS effect may be explained by a polarization modulated trap-assisted tunneling model. Our study not only provides a facile route to develop ferroelectric HfO2-based thin films but also explores their potential applications in FE-RS memories.

  19. Unraveling the magnetic properties of BiFe0.5Cr0.5O3 thin films

    Directory of Open Access Journals (Sweden)

    G. Vinai

    2015-11-01

    Full Text Available We investigate the structural, chemical, and magnetic properties on BiFe0.5Cr0.5O3 (BFCO thin films grown on (001 (110 and (111 oriented SrTiO3 (STO substrates by x-ray magnetic circular dichroism and x-ray diffraction. We show how highly pure BFCO films, differently from the theoretically expected ferrimagnetic behavior, present a very weak dichroic signal at Cr and Fe edges, with both moments aligned with the external field. Chemically sensitive hysteresis loops show no hysteretic behavior and no saturation up to 6.8 T. The linear responses are induced by the tilting of the Cr and Fe moments along the applied magnetic field.

  20. Exchange bias in a mixed metal oxide based magnetocaloric compound YFe0.5Cr0.5O3

    Science.gov (United States)

    Sharma, Mohit K.; Singh, Karan; Mukherjee, K.

    2016-09-01

    We report a detailed investigation of magnetization, magnetocaloric effect and exchange bias studies on a mixed metal oxide YFe0.5Cr0.5O3 belonging to perovskite family. Our results reveal that the compound is in canted magnetic state (CMS) where ferromagnetic correlations are present in an antiferromagnetic state. Magnetic entropy change of this compound follows a power law (∆SM∼Hm) dependence of magnetic field. In this compound, inverse magnetocaloric effect (IMCE) is observed below 260 K while conventional magnetocaloric effect (CMCE) above it. The exponent 'm' is found to be independent of temperature and field only in the IMCE region. Investigation of temperature and magnetic field dependence studies of exchange bias, reveal a competition between effective Zeeman energy of the ferromagnetic regions and anisotropic exchange energy at the interface between ferromagnetic and antiferromagnetic regions. Variation of exchange bias due to temperature and field cycling is also investigated.

  1. Zr and Sn substituted (Na0.5Bi0.5)TiO3 -based solid solutions

    Science.gov (United States)

    Ishchuk, V. M.; Gusakova, L. G.; Kisel, N. G.; Kuzenko, D. V.; Spiridonov, N. A.; Sobolev, V. L.

    2016-02-01

    The paper attempts to investigate the phase formation of a Zr- and Sn-substituted [(Na0.5Bi0.5)0.80Ba0.20](Ti1-yBy)O3 system during its solid state synthesis. The synthesis was found to be a multi-step process associated with the formation of a number of intermediate phases which however depended on the compositions and sintering temperatures. Single phase solid solutions were obtained when the sintering temperature was increased to 1000 °C-1100 °C. Increase in the concentration of substituting ions, on the one hand, tends to linearly increase the crystal cell size whereas the tolerance factor, on the other hand, gets reduced bolstering the stability of anti-ferroelectric phase as compared to that of ferroelectric phase’.

  2. Structural phase transitions and piezoelectric anomalies in ordered Sc0.5Ga0.5N alloys

    Indian Academy of Sciences (India)

    A M Alsaad; A A Ahmad

    2007-08-01

    Local-density approximation calculations (LDA) within density functional theory (DFT) and Berry phase approach within modern theory of polarization are performed to predict the structural and piezoelectric properties of ordered Sc0.5Ga0.5N alloys under compressive and tensile in-plane strain. This alloy is found to exhibit a tremendous piezoelectric response, associated with a phase transition from nonpolar 63/(6h) space group to a polar 63(6v) structure, at fixed Ga and Sc compositions when continuously changing the experimental accessible parameters (i.e. the compressive and tensile strain). The mechanism of the effects behind such anomalous behaviour is revealed and explained.

  3. Structural and Magnetic Properties of Bi0.5Sr0.5FeO3 Multiferroic Ceramics

    Science.gov (United States)

    Puhan, Ashalata; Bhushan, Bhavya; Rout, Dibyaranjan

    2016-09-01

    Phase pure BiFeO3 (BFO) and Bi0.5Sr0.5FeO3 (BFSO) ceramics were synthesized by solid state reaction method at different sintering conditions. Structural characterization with XRD revealed that the rhombohedral phase changed to cubic due to substitution of Sr in the A- site of BFO. SEM micrographs of BSFO samples indicated improved microstructure with higher density particularly the samples sintered for longer durations. The XPS data suggested the change in oxidation state of Fe from Fe3+ to Fe2+ as a result of aliovalent substitution of Sr at Bi site. As a consequence, oxygen vacancies were created to neutralize charge disorder. The BSFO samples exhibited ferromagnetism with enhanced remnant magnetization and coercive field as compared to the linear magnetization in BFO. These improved results obtained by Sr doping were majorly due to the structural change and creation of oxygen vacancies.

  4. Permittivity and modulus spectroscopic study of BaFe0.5Nb0.5O3 ceramics

    Directory of Open Access Journals (Sweden)

    Subrat K. Kar

    2013-12-01

    Full Text Available Ba(Fe0.5Nb0.5O3 (BFN powder was synthesized in single perovskite phase by conventional solid state reaction route and BFN ceramic was obtained by uniaxial pressing and sintering at 1350 °C. Complex immittance like: permittivity and modulus spectroscopic formalism were simultaneously used to explain dielectric behaviour of the ceramics. The activation energy calculated from dielectric relaxation below 100 °C was found to be ~0.19 eV. The activation energy obtained from modulus spectra above 100 °C was ~0.59 eV. The space charge polarization model was used to explain the origin of relaxation and “giant” permittivity of BFN ceramics near room temperature.

  5. Structural, dielectric and transport properties of Pb(Mn0.5W0.5)O3

    Indian Academy of Sciences (India)

    V L Mathe; K K Patankar; S D Lotke; P B Joshi; S A Patil

    2002-08-01

    Polycrystalline Pb(Mn0.5W0.5)O3, a ferroelectric oxide having perovskite structure, was prepared by high temperature solid state reaction technique. Preliminary X-ray diffraction analysis confirms single phase formation with the lattice parameters = 7.2501 Å, = 8.1276 Å and = 12.0232 Å. Room temperature dielectric constant (' ) and loss tangent (tan ) were scanned with respect to frequency in the range 100 Hz–1 MHz. Detailed study of dielectric constant and electrical conductivity reveals a phase change around 400 K, which is quite different from those in the other materials of the same type. Further, the seebeck coefficient () is temperature independent. The conduction is interpreted as due to small polaron hopping.

  6. Magnetoresistive memory in phase-separated La0.5Ca0.5MnO3

    Energy Technology Data Exchange (ETDEWEB)

    Sacanell, J. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina)]. E-mail: sacanell@cnea.gov.ar; Parisi, F. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina); Levy, P. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina); Ghivelder, L. [Instituto de Fisica, UFRJ, Rio de Janeiro (Brazil)

    2004-12-31

    We have studied a non-volatile memory effect in the mixed valent compound La0.5Ca0.5MnO3 induced by magnetic field (H). In a previous work (Phys. Rev. B 65 (2002) 104403), it has been shown that the response of this system upon application of H strongly depends on the temperature range, related to three well-differentiated regimes of phase separation occurring below 220K. In this work we compare memory capabilities of the compound, determined following two different experimental procedures for applying H, namely zero-field cooling and field cooling the sample. These results are analyzed and discussed within the scenario of phase separation.

  7. Response of Surface Soil Hydrology to the Micro-Pattern of Bio-Crust in a Dry-Land Loess Environment, China.

    Science.gov (United States)

    Wei, Wei; Yu, Yun; Chen, Liding

    2015-01-01

    The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust) to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes.

  8. Carbon Dynamics of Surface Soil after Land Use Change in a Seasonal Tropical Forest in North-eastern Thailand: Application of a Stable Carbon Isotope Mixing Model

    Science.gov (United States)

    Sakai, M.; Visaratana, T.; Sukchan, S.; Thaingam, R.; Okada, N.

    2015-12-01

    Globally, soil is vital to the mitigation of climate change. In tropical forests, the soil contains an estimated 216 Gt of carbon, equivalent to half of the total carbon in the tropical forest ecosystem. Little is known regarding changes in soil carbon following land use changes in tropical regions. We examined the differences in carbon dynamics in a chronosequence of Acacia mangium plantations established on grasslands following the deforestation of natural forest in north-eastern Thailand. The study site was located at the Sakaerat Silvicultural Research Station (14º28'06.1″N, 101º54'15.0″E; altitude 420 m asl), Nakhon Rachasima Province, north-eastern Thailand. Mean annual air temperature was 26ºC, and annual precipitation was 1,100 mm, with a dry (November-April) and wet (May-October) season. Soil carbon and the stable carbon isotope ratio (d13C) in the surface soil (0-5 and 5-10 cm deep) were determined at 12 and 24 years following establishment of A. mangium plantations, as well as for secondary forest and grassland. Using the stable carbon isotope mixing model based on differences in the natural abundance of d13C in plants with C3 (i.e., trees) and C4 (i.e., grasses) pathways for CO2 fixation, the amount of soil carbon derived from the plantations, forest, and grassland was calculated. Soil carbon at a depth of 10 cm was higher in the secondary forest (1,929 gCm-2) and grassland (2,508 gCm-2) than in the plantations (1,703 gCm-2 at 12 years, 1,673gCm-2 at 24 years). Soil carbon derived from A. mangium was 67% (0-5 cm deep) and 62% (5-10 cm deep) of total soil carbon at 12 years, and was 100% (0-5 cm deep) and 90% (5-10 cm deep) at 24 years in the plantations. We found that most of the soil carbon at a depth of 0-5 cm in the young plantation changed from grass-derived to tree-derived carbon within a relatively short period of 24 years. Because of changes in soil carbon, exotic, fast growing plantations like those of A. mangium are needed to quickly

  9. Ir0.5Pt0.5O2阳极的电催化活性及氧化电解水制备%Electrocatalytic performance of Ir0.5Pt0.5O2 anode and preparation of electrolyzed oxidizing water

    Institute of Scientific and Technical Information of China (English)

    高洁; 朱玉婵; 任占冬; 李文阳; 全姗姗; 刘晔; 王又容; 柴波

    2015-01-01

    Electrolyzed oxidizing water (EOW), as an innovative disinfectant characterized by its high efficiency, broad antimicrobial spectrum, and non-toxic residues, has been broadly used in health care industry, medicines, agriculture, and food processing. EOW is usually generated by electrolysis of a dilute NaCl solution in a chamber with two cells separated by membrane, and is obtained from the anode side. But low current efficiency and short service life of the anode in EOW generators restrict the application of EOW. Ir0.5Pt0.5O2 anode was prepared by the improved Adams fusion method. The properties of Ir0.5Pt0.5O2 anode was investigated with X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemistry cyclic voltammetry (CV). The crystal type is rutile with (101), (002) and (301) crystal planes. A large number of cellular structures were observed on the surface of the anode, which greatly increased specific surface area of the anode. With increasing specific surface area, electric charge was enhanced to 0.4 mC, which was 2.65 times of pure IrO2. Electrochemical characteristics of the anode surface, such as oxidation peaks at 1.0 V(Pt-OH) and 0.9 V(Ir3+/Ir4+) proved the formation of platinum iridium oxide. The activities of chlorine evolution and oxygen evolution were also studied through linear sweep voltammetry (LSV). Compared with IrO2, chlorine evolution activity in unit apparent surface area increased significantly, but oxygen evolution activity decreased obviously. The slope of Tafel was 56.3 mV·dec−1 for chlorine evolution reaction (CER), and the mechanism was Volmer-Heyrovsky in which the rate controlling step was electrochemical desorption. The slope of Tafel was 126.6 mV·dec−1 for oxygen evolution reaction (OER), and the rate controlling step was formation of surface hydroxide on the catalyst surface. Electrochemical surface structure and electrochemical performance of Ir0.5Pt0.5O2 oxide coatings in 1 g · L−1 NaCl solution were

  10. Finite Element Analysis for Cohesive Soil, Stress and Consolidation Problems Using Bounding Surface Plasticity Theory.

    Science.gov (United States)

    1983-12-01

    Formulation of Soil Plasticity ," Chapter in Soils under Cyclic and Transient Loading, 3. Wiley and Sons, 0. C. Zienkiewiez and G. N. Pande, eds., 1982. 2...and . S. DeNatale, "Numerical ’-’. Implementation of a Bounding Surface Soil Plasticity Model," Proc. of theInt. Symp. on Num. Models in Geomech. , V2

  11. The SMAP level 4 surface and root zone soil moisture data assimilation product

    Science.gov (United States)

    The NASA Soil Moisture Active Passive (SMAP) mission is scheduled for launch in January 2015 and will provide L-band radar and radiometer observations that are sensitive to surface soil moisture (in the top few centimeters of the soil column). For several of the key applications targeted by SMAP, ho...

  12. Physical characterization, spectral response and remotely sensed mapping of Mediterranean soil surface crusts

    NARCIS (Netherlands)

    Jong, S.M. de; Addink, E.A.; Duijsing, D.; Beek, L.P.H. van

    2011-01-01

    Soil surface crusting and sealing are frequent but unfavorable processes in Mediterranean areas. Soil crust and seals form on bare soil subject to high-intensity rainfall, resulting in a hard, impenetrable layer that impedes infiltration and hampers the germination and establishment of plants. The a

  13. Organochlorine pesticides and polychlorinated biphenyls in surface soils of Novi Sad and bank sediment of the Danube River.

    Science.gov (United States)

    Skrbic, Biljana; Cvejanov, Jelena; Durisic-Mladenovic, Natasa

    2007-01-01

    The contents of 16 organochlorine pesticides (OCPs) and six so-called indicator polychlorinated biphenyls (PCBs) were determined in the surface zone (0-5 cm) of soil and sediment samples, taken from different locations in the city of Novi Sad, capitol of Vojvodina Province (North of the Serbia) covering residential and commercial area, recreational and arable zone. The total organochlorine pesticides concentration in soil varied from 2.63 to 31.78 ng g(-1) dry weight, while the level in sediment was 10.35 ng g(-1) dry weight. Maximum content of identified individual organochlorine pesticide in soil samples was 10.40 ng g(-1) dry weight for p, p-DDE in the market garden and 6.31 ng g(-1) dry weight for p, p'-DDT in sediment of the Danube River, although their application is restricted in Serbia. Some of investigated PCBs were identified only in the soil samples from a park-school backyard in the city downtown (0.32 ng g(-1) dry weight) and market garden (0.22 ng g(-1) dry weight), and also in sediment sample from left bank of the Danube River (0.41 ng g(-1) dry weight). Data of the OCPs and PCBs present in this study were compared with the ones found for soils and river sediments throughout the world, and with limit values set by soil and sediment quality guidelines. Also, correlation between the levels of certain pesticides and soil characteristics (organic matter, pH and clay content) was investigated.

  14. Changes in Temperature and Fate of Soil Organic Matter in an Andisol due to Soil Surface Burning

    Science.gov (United States)

    Obuchi, Atsuko; Nishimura, Taku; Mizoguchi, Masaru; Imoto, Hiromi; Miyazaki, Tsuyoshi

    This is a print of a camera-ready Japanese manuscript for the Transactions of JSIDRE. This will provide an example and directions for the layout and font size/style to be used. Please refer to this when preparing the headings, figures/table and text of your manuscript. The manuscript should be submitted on A4 size. Changes in temperature, soil moisture, and carbon and nitrogen contents were measured in Andisol under soil surface burning. Soil samples were packed into an unglazed cylinder of 15 cm inner diameter and 30 cm high. Charcoal was burned for 6 hours on the surface of the soil column. During the burning soil surface temperature rose to between 600-700°C. In initially wet soil, rise in soil temperature was retarded for a while at around 95-100°C. On the other hand, in initially dry Toyoura sand showed more rapid temperature increase without retardation. The temperature retardation in the wet soil could be caused by consumption of latent heat by vaporization of soil water. Rate of proceeding of the 100°C front was proportional to square root of the burning time. This indicates that higher the initial volumetric water content, shallower the depth affected by burning. Soil samples suffered temperature above 500°C still had total carbon and nitrogen contents of over 20 and 1 g kg-1, respectively, whereas the soil that was heated up to over 500°C by muffle furnace contained less than 0.4 and 0.1 g kg-1 of the carbon and nitrogen.

  15. Mössbauer study of Cu0.5Fe0.5Cr2S4

    Science.gov (United States)

    Ok, Hang Nam; Baek, Kyung Seon; Lee, Heung Soo; Kim, Chul Sung

    1990-01-01

    Cu0.5Fe0.05Cr2S4 has been studied by Mössbauer spectroscopy and x-ray diffraction. The crystal structure is found to be a cubic spinel with the lattice parameter a0=9.922 Å. The temperature dependence of both the magnetic hyperfine field and magnetization is explained by the Néel theory of ferrimagnetism using three exchange integrals: JFe-Cr/kB=-13.7 K, JFe-Fe/kB=-8.3 K, and JCr-Cr/kB=8.7 K.

  16. Oxidation Behavior of a Refractory NbCrMo0.5Ta0.5TiZr Alloy

    Science.gov (United States)

    2014-04-01

    Laves ), were identified [10]. The lattice parameters of these phases were deter- mined to be a = 324.76 ± 0.16, 341 ± 1, and 740.0 ± 0.5 pm...Table 5. Locations of former BCC1 (regions 1 and 2 in Fig. 12), BCC2 (regions 3 and 4), and Laves phases (region 5) are clearly distinguished. During...the Laves phase (gray particles, similar to region 5 in Fig. 12) leads to formation of sharp, almost linear cracks, some of which are parallel to each

  17. Open-framework Borophosphate:(NH4)0.5FeⅡ0.5FeⅢ0.5·(H2O)2 BP2O8·0.5 H2O

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    An open-framework ammonium ferricborophosphate compound was synthesized by mild hydrothermal condition at 110°C. The crystal structure has been determined by single-crystal X-ray diffraction analysis: hexagonal, P6522, a = 9.452(2)A, c = 15.698(5)A,α = 90°,γ = 120°,Z= 6, Mr = 310.58, V = 1214.0(5)A3, Dc = 2.549 g/cm3, μ= 2.311mm-1, F(000) = 930. The chiral tetrahedral-tetrahedral helical ribbons are linked by the mixed valance FeII/FeIIIO6 coordinated octahedra. The ammonium ions are located inside the free loop of helical ribbons close to the inner wall of the helical channels{[BP2O8]3-}, effecting on balancing charge and stabilizing helical ribbons.

  18. The use of physicochemical methods to detect organic food soils on stainless steel surfaces.

    Science.gov (United States)

    Whitehead, K A; Benson, P; Smith, L A; Verran, J

    2009-11-01

    Food processing surfaces fouled with organic material pose problems ranging from aesthetic appearance, equipment malfunction and product contamination. Despite the importance of organic soiling for subsequent product quality, little is known about the interaction between surfaces and organic soil components. A range of complex and defined food soils was applied to 304 stainless steel (SS) surfaces to determine the effect of type and concentration of soil on surface physicochemical parameters, viz surface hydrophobicity (DeltaG(iwi)), surface free energy (gamma(s)), Lifshitz van der Waals (gamma_LW(s)), Lewis acid base (gamma_AB(s)), electron acceptor (gamma_+(s) ) and electron donor (gamma_-(s) ) measurements. When compared to the control surface, changes in gamma_AB(s), gamma_+(s) and gamma_-(s) were indicative of surface soiling. However, soil composition and surface coverage were heterogeneous, resulting in complex data being generated from which trends could not be discerned. These results demonstrate that the retention of food soil produces changes in the physicochemical parameters of the surface that could be used to indicate the hygienic status of a surface.

  19. Unexpected ferromagnetic ordering enhancement with crystallite size growth observed in La{sub 0.5}Ca{sub 0.5}MnO₃ nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Iniama, G.; Ita, B. I. [Department of Pure and Applied Chemistry, University of Calabar, Calabar (Nigeria); Presa, P. de la, E-mail: pmpresa@ucm.es; Hernando, A. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Físicas, Dpto. Física de Materiales, Univ. Complutense de Madrid, 28040 Madrid (Spain); Alonso, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Instituto de Ciencia de Materiales, CSIC, 28049-Madrid (Spain); Multigner, M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Cortés-Gil, R.; Ruiz-González, M. L. [Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain); Gonzalez-Calbet, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain)

    2014-09-21

    In this paper, the physical properties of half-doped manganite La{sub 0.5}Ca{sub 0.5}MnO₃ with crystallite sizes ranging from 15 to 40 nm are investigated. As expected, ferromagnetic order strengthens at expense of antiferromagnetic one as crystallite size is reduced to 15 nm. However, contrary to previously reported works, an enhancement of saturation magnetization is observed as crystallite size increases from 15 to 22 nm. This unexpected behavior is accompanied by an unusual cell volume variation that seems to induce ferromagnetic-like behavior at expense of antiferromagnetic one. Besides, field cooled hysteresis loops show exchange bias field and coercivity enhancement for increasing cooling fields, which suggest a kind of core-shell structure with AFM-FM coupling for crystallite sizes as small as 15 nm. It is expected that inner core orders antiferromagnetically, whereas uncompensated surface spins behave as spin glass with ferromagnetic-like ordering.

  20. Observation of anomalous transition in the upper critical fields of Nb/Nb sub 0. 5 Zr sub 0. 5 multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kuwasawa, Y.; Hayano, U.; Tosaka, T.; Nakano, S. (Chiba Univ. (Japan). Dept. of Physics); Matuda, S. (Shiba Univ. (Japan). Coll. of Arts and Sciences)

    1990-01-15

    An anomalous upturn in the parallel upper critical field is observed in the Nb/Nb{sub 0.5}Zr{sub 0.5} multilayer with the period {Lambda}=400 A and 500 A, as predicted by Takahashi and Tachiki for multilayer composed of two materials with different electronic diffusion constants and equal transition temperature. We have found the anomalous feature in a temperature dependence of transition width {Delta}H{sub c2parallel} in the region where the upturn occurs. In the angular dependence of the upper critical fields, the slope dH{sub c2}/d{theta} near the field direction parallel to the film surface also exhibits an abrupt change in the range of upturn. (orig.).

  1. Electric-pulse-induced resistance switching effect in the bulk of La0.5Ca0.5MnO3 ceramics

    Directory of Open Access Journals (Sweden)

    M. L. Wu

    2014-04-01

    Full Text Available In the majority of contributions, the electrical–pulse-induced resistance (EPIR switching effect of perovskite manganites is thought to originate from the extrinsic interfacial Schottky barrier between the metal electrode and the surface of sample. In this work, La0.5Ca0.5MnO3 (LCMO ceramic samples were synthesized by solid state reaction and the transport properties, especially, the EPIR effect and memristor behavior were investigated under 4-wire method using silver-glue as electrodes. Although the I-V characteristic of LCMO shows an ohmic linearity under the 4-wire mode at room temperature, a stable and remarkable EPIR can still be observed when the pulse voltage is more than a critical value. This bulk EPIR effect is novel for rare - earth doped manganites.

  2. Influence of different heat treatment programs on properties of sol–gel synthesized (Na0.5K0.5)NbO3 (KNN) thin films

    Indian Academy of Sciences (India)

    S Wiegand; S Flege; O Baake; W Ensinger

    2012-10-01

    Thin films of (Na0.5K0.5)NbO3 (KNN) were synthesized on Pt/Ti/SiO2/Si substrates with repeated spin-coating after fabrication of the precursor solution by a sol–gel process. The KNN precursor solution was prepared from K- and Na-acetate, Nb-pentaethoxide and 1,3-propanediol. Based on three characteristic temperatures derived from thermal analysis (TG–DTA) experiments, five heat treatment programs were developed. All programs lead to single phase perovskite KNN films with random crystal orientation, but only the programs that included a treatment after each single spin-coating step provided pore free surfaces with grains of about 100 nm size. The lowest leakage current at 150 kV cm-1 was obtained for the temperature program that included pyrolysis and calcination steps after each deposited layer.

  3. Impedance measurements in different alkaline solutions on an oxygen-evolving Lasub(0. 5)Srsub(0. 5)CoO/sub 3/ electrode

    Energy Technology Data Exchange (ETDEWEB)

    Willems, H.; Moers, M.; Broers, G.H.J.; Wit, J.H.W. de

    1985-10-25

    It was found that the oxygen evolution reaction on Lasub(0.5)Srsub(0.5)CoO/sub 3/ in strong alkaline solutions has a Tafel slope of proportional 60 mV/dec and a reaction order at constant overpotential with respect to the KOH activity of 0.6-0.8. From impedance measurements differential Tafel slopes were calculated and were found to be proportional 60 mV/dec at overpotentials >250 mV. Effective capacitances having a broad maximum at an overpotential of about 200 mV in all alkaline solutions were calculated. The effective capacitance increased with increasing KOH concentration. Furthermore, the material decomposed at the surface when exposed to strong oxygen evolution. From the results a modified Krasil'shchikov reaction path is analysed. (orig.).

  4. Electric-pulse-induced resistance switching effect in the bulk of La0.5Ca0.5MnO3 ceramics

    Science.gov (United States)

    Wu, M. L.; Yang, C. P.; Shi, D. W.; Wang, R. L.; Xu, L. F.; Xiao, H. B.; Baerner, K.

    2014-04-01

    In the majority of contributions, the electrical-pulse-induced resistance (EPIR) switching effect of perovskite manganites is thought to originate from the extrinsic interfacial Schottky barrier between the metal electrode and the surface of sample. In this work, La0.5Ca0.5MnO3 (LCMO) ceramic samples were synthesized by solid state reaction and the transport properties, especially, the EPIR effect and memristor behavior were investigated under 4-wire method using silver-glue as electrodes. Although the I-V characteristic of LCMO shows an ohmic linearity under the 4-wire mode at room temperature, a stable and remarkable EPIR can still be observed when the pulse voltage is more than a critical value. This bulk EPIR effect is novel for rare - earth doped manganites.

  5. Upper critical field and AC-Susceptibility studies on FeTe0.5Se0.5 superconductor

    Science.gov (United States)

    Zargar, Rayees A.; Pal, Anand; Hafiz, A. K.; Awana, V. P. S.

    2015-06-01

    In this study we present synthesis and characterization of FeTe0.5Se0.5 sample that has been prepared by solid state reaction route by encapsulation of stoichiometric high purity (5N) ingredients in an evacuated quartz tube at 750 °C. The resultant compound is crystallized in single phase tetragonal structure with space group P4/nmm, having lattice parameters a = 3.792(1) Å and c = 6.0081(3) Å. The studied compound is superconducting at below 13K in both magnetic and transport measurements. Further superconductivity is barely affected by external applied magnetic field, giving rise to upper critical field of above 180 Tesla at 0 K. The sample is studied extensively for AC susceptibility measurements in superconducting state. The AC drive field and frequency are varied from 1-13 Oe and 33-9999 Hz respectively. It is concluded that though the grain boundaries of this superconductor are mainly metallic the minor (undetectable in XRD) foreign phases and the role of porosity cannot be ruled out completely. This is because both frequency and amplitude affects slightly the superconductivity coupling temperature of the grains.

  6. Pressure effect on electronic properties of Sc{sub 0.5}In{sub 0.5}N compound

    Energy Technology Data Exchange (ETDEWEB)

    Perez, William Lopez [Departamento de Fisica, Universidad del Norte, Barranquilla (Colombia); Rodriguez M., Jairo Arbey; Gonzalez, Rafael; Fajardo, Fabio [Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia); Mancera, Luis [Nachwuchsgruppe Theorie, University of Ulm (Germany)

    2009-03-15

    We have applied the full potential linearized augmented plane wave method (FP-LAPW) within the density functional theory to investigate the structural and electronic properties of the Sc{sub 0.5}In{sub 0.5}N compound in the wurtzite and sodium chloride structures. We have analyzed the relative stability of this ternary compound in the two studied phases. We found that the wurtzite structure is the most stable phase, with the minimum {proportional_to}0.14 eV/(unit cell) lower than in the sodium chloride phase. A phase transition from wurtzite to sodium chloride structure was observed, with transition pressure {proportional_to}1.9 GPa. Our results predict a direct semiconductor in wurtzite structure and an indirect semiconductor in sodium chloride phase. We investigate the pressure effect on the electronic properties of this ternary compound in the two phases studied. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. High current superconductivity in FeSe0.5Te0.5-coated conductors at 30 tesla.

    Science.gov (United States)

    Si, Weidong; Han, Su Jung; Shi, Xiaoya; Ehrlich, Steven N; Jaroszynski, J; Goyal, Amit; Li, Qiang

    2013-01-01

    Although high-temperature superconductor cuprates have been discovered for more than 25 years, superconductors for high-field application are still based on low-temperature superconductors, such as Nb(3)Sn. The high anisotropies, brittle textures and high manufacturing costs limit the applicability of the cuprates. Here we demonstrate that the iron superconductors, without most of the drawbacks of the cuprates, have a superior high-field performance over low-temperature superconductors at 4.2 K. With a CeO(2) buffer, critical current densities >10(6)  A cm(-2) were observed in iron-chalcogenide FeSe(0.5)Te(0.5) films grown on single-crystalline and coated conductor substrates. These films are capable of carrying critical current densities exceeding 10(5) A cm(-2) under 30 tesla magnetic fields, which are much higher than those of low-temperature superconductors. High critical current densities, low magnetic field anisotropies and relatively strong grain coupling make iron-chalcogenide-coated conductors particularly attractive for high-field applications at liquid helium temperatures.

  8. Study of Co0.5Zn0.5Fe2O4 nanoparticles for magnetic hyperthermia

    Science.gov (United States)

    Kamzin, A. S.; Nikam, D. S.; Pawar, S. H.

    2017-01-01

    The structural characteristics, magnetic properties, and processes of magnetic heating in an alternating magnetic field of magnetic nanoparticles (MNPs) Co0.5Zn0.5Fe2O4 (cobalt-zinc ferrite, CZF) are studied to explore the possibilities of their application in medicine, namely, for magnetic hyperthermia treatment (the heating of particles with external alternating magnetic field). CZF magnetic nanoparticles were obtained by coprecipitation using sodium hydroxide (NaOH) as a precipitating agent. Based on the data obtained by transmission electron microscopy in the transmission geometry, it is found that CZF magnetic nanoparticles have an almost spherical shape with an average particle size of 13 nm. X-ray diffraction and Mössbauer studies showed that CZF magnetic nanoparticles are single-phase, and their structure corresponds to a cubic spinel structure. The saturation magnetization M s of CZF nanoparticles is measured at room temperature using a vibrating sample magnetometer. The possibility of heating CZF magnetic nanoparticles with an external alternating magnetic field was studied using an induction heating system. The specific absorption rate is determined by applying an external alternating magnetic field in the range of 167.5 to 335.2 Oe at a fixed frequency of 265 kHz. It is found that the maximum amount of heat (114.98 W/g) is produced at a concentration of 5 mg/L under a field of 335.2 Oe.

  9. Hot-pressing of monazite Ce0.5Pr0.5PO4 ceramic and its chemical durability

    Science.gov (United States)

    Teng, Yuancheng; Zeng, Pan; Huang, Yi; Wu, Lang; Wang, Xiaohuan

    2015-10-01

    Pr-doped monazite-(Ce) ceramic with the composition of Ce0.5Pr0.5PO4 was successfully fabricated utilizing uniaxial hot-press sintering process. The effects of sintering temperature and holding time on bulk density and microstructure of ceramic were investigated, and sintering parameters were optimized. The chemical durability of ceramic was examined through MCC-1 test. The relatively optimal sintering temperature and holding time at 30 MPa were 1150 °C and 2 h, respectively. The hot-pressed ceramic has a smaller fine-grained, closer packed structure than the pressureless sintered ceramic. The element mapping images of Ce, Pr, P and O show that all the elements are almost distributed homogeneously in the monazite ceramics. Furthermore, the normalized dissolution rates of Ce and Pr decrease with increasing time and remain almost unchanged after 28 days. The 42 days normalized dissolution rates of RL(Ce) and RL(Pr) were equal to 5.7 × 10-6 and 5.3 × 10-5 g m-2 d-1, respectively.

  10. Magnetic structure of the kagome mixed compound (Co(0.5)Ni(0.5))(3)V(2)O(8).

    Science.gov (United States)

    Qureshi, N; Fuess, H; Ehrenberg, H; Ouladdiaf, B; Rodríguez-Carvajal, J; Hansen, T C; Wolf, Th; Meingast, C; Zhang, Q; Knafo, W; Löhneysen, H V

    2008-06-11

    We report the magnetic structure of (Co(0.5)Ni(0.5))(3)V(2)O(8) (CNVO) deduced by single crystal neutron diffraction. This compound exhibits features which differ from that of its parent compounds, which are absolutely collinear along the a axis for Co(3)V(2)O(8) (CVO) or exhibit magnetic moments predominantly in the a-b plane with small components along c in the case of Ni(3)V(2)O(8) (NVO). The averaged magnetic moments of the statistically distributed Ni(2+) and Co(2+) ions in CNVO are oriented in the a-c plane and form loops of quasiferromagnetically coupled spins. These loops are connected along the a axis and separated along the c axis by cross-tie spins forming a quasiferromagnetic wave with the upper part of the respective neighbouring loops. The magnetic moments are sinusoidally modulated by the propagation vector k = (0.49,0,0) with an average amplitude of 1.59(1) μ(B) for a magnetic ion on a cross-tie site and 1.60(1) μ(B) for the spine site. In addition to neutron diffraction, specific heat and magnetization data, which confirm that the only magnetic phase transition above 1.8 K is the onset of antiferromagnetic order at T(N) = 7.4(1) K, are presented.

  11. DEGRADATION OF 0.5Cr-0.5Mo-0.25V STEEL MICROSTRUCTURE DURING EXPLOITATION

    Directory of Open Access Journals (Sweden)

    Viera Homolová

    2011-08-01

    Full Text Available Degradation of 0.5Mo-0.5Cr-0.25V material after long-term high-temperature service has been studied by means of microstructure and mechanical properties analysis. Samples were taken from the pipeline with steam leaking found after almost 200,000 h service at 565 °C. The microstructure and properties have been compared with similar materials at similar exposure conditions without any signs of the rupture. Highly tempered ferrite contains secondary particles of MC, M2C and a kind of Cr-rich carbide (M23C6 and/or M7C3 in all materials studied. The difference have been found in the values of hardness. Fractures of samples after the impact test at various temperatures with typical embrittled features are also described. Analysis of the material service history like warm and cold starts-up, conditions of thermal and mechanical fatigue, together with microstruc¬ture and mechanical properties lead to the conclusion that the material was overtempered. The exhaustion of material deformationability resulted in the rupture-leakage of a component in the place of highest stresses.

  12. Magnetic structure of the kagome mixed compound (Co0.5Ni0.5)3V2O8

    Science.gov (United States)

    Qureshi, N.; Fuess, H.; Ehrenberg, H.; Ouladdiaf, B.; Rodríguez-Carvajal, J.; Hansen, T. C.; Wolf, Th; Meingast, C.; Zhang, Q.; Knafo, W.; Löhneysen, H. v.

    2008-06-01

    We report the magnetic structure of (Co0.5Ni0.5)3V2O8 (CNVO) deduced by single crystal neutron diffraction. This compound exhibits features which differ from that of its parent compounds, which are absolutely collinear along the a axis for Co3V2O8 (CVO) or exhibit magnetic moments predominantly in the a-b plane with small components along c in the case of Ni3V2O8 (NVO). The averaged magnetic moments of the statistically distributed Ni2+ and Co2+ ions in CNVO are oriented in the a-c plane and form loops of quasiferromagnetically coupled spins. These loops are connected along the a axis and separated along the c axis by cross-tie spins forming a quasiferromagnetic wave with the upper part of the respective neighbouring loops. The magnetic moments are sinusoidally modulated by the propagation vector k = (0.49,0,0) with an average amplitude of 1.59(1) μB for a magnetic ion on a cross-tie site and 1.60(1) μB for the spine site. In addition to neutron diffraction, specific heat and magnetization data, which confirm that the only magnetic phase transition above 1.8 K is the onset of antiferromagnetic order at TN = 7.4(1) K, are presented.

  13. High-pressure structural behaviour of Cu0.5Fe0.5Cr2S4

    DEFF Research Database (Denmark)

    Waśkowska, A.; Gerward, Leif; Staun Olsen, J.

    2013-01-01

    -pressure behaviour. We report here the first experimental and theoretical determinations of the bulk modulus: B0=106(2)GPa and B′'0=4.0 (experimental), and B0=96GPa and B′0=3.9 (calculated). Moreover, a pressure-induced structural and electronic phase transformation occurs at 14.5GPa accompanied by a volume collapse......The structural behaviour of Cu0.5Fe0.5Cr2S4 has been studied experimentally and theoretically at pressures up to 44GPa. The experiments are supported by density functional calculations using the full-potential linear muffin-tin orbital method for investigating ground state properties and high...... of about 6%. Tentatively, the high-pressure phase is assigned the defect NiAs structure of Cr3S4 type with space group I2/m (12). The mechanism of the phase transition is explained by a Jahn–Teller type distortion, associated with geometrical frustration and magnetic spin changes....

  14. Role of soil health in maintaining environmental sustainability of surface coal mining.

    Science.gov (United States)

    Acton, Peter M; Fox, James F; Campbell, J Elliott; Jones, Alice L; Rowe, Harold; Martin, Darren; Bryson, Sebastian

    2011-12-01

    Mountaintop coal mining (MCM) in the Southern Appalachian forest region greatly impacts both soil and aquatic ecosystems. Policy and practice currently in place emphasize water quality and soil stability but do not consider upland soil health. Here we report soil organic carbon (SOC) measurements and other soil quality indicators for reclaimed soils in the Southern Appalachian forest region to quantify the health of the soil ecosystem. The SOC sequestration rate of the MCM soils was 1.3 MgC ha(-1) yr(-1) and stocks ranged from 1.3 ± 0.9 to 20.9 ± 5.9 Mg ha(-1) and contained only 11% of the SOC of surrounding forest soils. Comparable reclaimed mining soils reported in the literature that are supportive of soil ecosystem health had SOC stocks 2.5-5 times greater than the MCM soils and sequestration rates were also 1.6-3 times greater. The high compaction associated with reclamation in this region greatly reduces both the vegetative rooting depth and infiltration of the soil and increases surface runoff, thus bypassing the ability of soil to naturally filter groundwater. In the context of environmental sustainability of MCM, it is proposed that the entire watershed ecosystem be assessed and that a revision of current policy be conducted to reflect the health of both water and soil.

  15. Soil surface temperatures reveal moderation of the urban heat island effect by trees and shrubs

    DEFF Research Database (Denmark)

    Edmondson, Jill L; Stott, Iain; Davies, Zoe G

    2016-01-01

    Urban areas are major contributors to air pollution and climate change, causing impacts on human health that are amplified by the microclimatological effects of buildings and grey infrastructure through the urban heat island (UHI) effect. Urban greenspaces may be important in reducing surface...... in domestic gardens, which tend to be smaller, were less effective at reducing summer soil surface temperatures. Our findings reveal that the UHI effects soil temperatures at a city-wide scale, and that in their moderating urban soil surface temperature extremes, trees and shrubs may help to reduce...... the adverse impacts of urbanization on microclimate, soil processes and human health....

  16. COMPARISON OF 0.5% ROPIVACAINE & 0.5% BUPIVACAINE IN EPIDURAL ANAESTHESIA FOR PATIENTS UNDERGOING ABDOMINAL HYSTERECTOMY

    Directory of Open Access Journals (Sweden)

    Durga Shankar

    2015-07-01

    Full Text Available Ropivacaine is a new intermediate - acting amide local anesthetic which is structurally closely related to a chemical group of amino amides in present clinical use e.g. bupivacaine and mepivacaine . Ropivacaine has pharmacodynamic and pharmacokinetic properties in animals resembling those of bupivacaine. 1 - 3 In human volunteers, ropivacaine has been shown to be less prone than bupivacaine to produce mild central nervous system and cardiovascular changes after intravenous infusion Hence we designed a study to compare ropivacaine 0.5% with bupivacaine 0.5% for epidural anesthesia fo r abdominal hysterectomy. Healthy women, scheduled for elective abdominal hysterectomy were enrolled into this randomized, double - blind, parallel - group study. Epidural block was obtained with 20 ml of ropivacaine (group R or bupivacaine (group B and surgery started when anesthesia reached T6. Heart rate and blood pressure were assessed before the test dose and at five minute intervals for initial 30mins and then every 10mins until the full recovery. At the same intervals, sensory and motor block characteristics were determined. Adverse events were recorded. Sixty patients were enrolled and data available for analysis was 30 ropivacaine and 30 bupivacaine. Mean duration for total sensory blockade was 323.50±39.33mins for R group as compared to 312.0 ± 30.36mins for B group (p>0.05 . Motor onset time in group R was 17.26 ± 1.78 , 25.44 ± 1.79 and 28.28 ± 1.79mins for grade 1, 2 and 3 motor block respectively, compared to 16.73 ± 1.99 , 25.14 ± 2.05 and 28.66 ± 2.82mins for group B (p>0.05 . Duration of motor block in group R was 211.66 ± 32.91mins as compared to 288.66 ± 36.99mins in group B . (P value < 0.0001 . Analgesia was excellent in 83.33% cases and satisfactory in 10 % cases in group R as compared to 86.66% and 3.33% in group B respectively. 6.66% patients in group R and 10% patients in group B required intravenous fentanyl supplement and were

  17. High-resolution hydraulic parameter maps for surface soils in tropical South America

    Science.gov (United States)

    Marthews, T. R.; Quesada, C. A.; Galbraith, D. R.; Malhi, Y.; Mullins, C. E.; Hodnett, M. G.; Dharssi, I.

    2014-05-01

    Modern land surface model simulations capture soil profile water movement through the use of soil hydraulics sub-models, but good hydraulic parameterisations are often lacking, especially in the tropics. We present much-improved gridded data sets of hydraulic parameters for surface soil for the critical area of tropical South America, describing soil profile water movement across the region to 30 cm depth. Optimal hydraulic parameter values are given for the Brooks and Corey, Campbell, van Genuchten-Mualem and van Genuchten-Burdine soil hydraulic models, which are widely used hydraulic sub-models in land surface models. This has been possible through interpolating soil measurements from several sources through the SOTERLAC soil and terrain data base and using the most recent pedotransfer functions (PTFs) derived for South American soils. All soil parameter data layers are provided at 15 arcsec resolution and available for download, this being 20x higher resolution than the best comparable parameter maps available to date. Specific examples are given of the use of PTFs and the importance highlighted of using PTFs that have been locally parameterised and that are not just based on soil texture. We discuss current developments in soil hydraulic modelling and how high-resolution parameter maps such as these can improve the simulation of vegetation development and productivity in land surface models.

  18. Inverse magnetocaloric and exchange bias effects in single crystalline La0.5Sr0.5MnO3 nanowires.

    Science.gov (United States)

    Chandra, Sayan; Biswas, Anis; Datta, Subarna; Ghosh, Barnali; Raychaudhuri, A K; Srikanth, Hariharan

    2013-12-20

    We report the first observation of inverse magnetocaloric effect (IMCE) in hydrothermally synthesized single crystalline La0.5Sr0.5MnO3 nanowires. The core of the nanowires is phase separated with the development of double exchange driven ferromagnetism (FM) in the antiferromagnetic (AFM) matrix, whereas the surface is found to be composed of disordered magnetic spins. The FM phase scales with the effective magnetic anisotropy, which is directly probed by transverse susceptibility experiments. The surface exhibits a glassy behavior and undergoes spin freezing, which manifests as a positive peak (T(L) ~ 42 K) in the magnetic entropy change (-ΔS(M)) curves, thereby stabilizing the re-entrance of the conventional magnetocaloric effect. Precisely at T(L), the nanowires develop the exchange bias (EB) effect. Our results conclusively demonstrate that the mere coexistence of FM and AFM phases along with a disordered surface below their Néel temperature (T(N) ~ 210 K) does not trigger EB, but this develops only below the surface spin freezing temperature.

  19. Development of a surface scanning soil analysis instrument.

    Science.gov (United States)

    Falahat, S; Köble, T; Schumann, O; Waring, C; Watt, G

    2012-07-01

    ANSTO is developing a nuclear field instrument for measurement of soil composition; particularly carbon. The instrument utilises the neutron activation approach with clear advantages over existing soil sampling and laboratory analysis. A field portable compact pulsed neutron generator and γ-ray detector are used for PGNAA and INS techniques simultaneously. Many elements can be quantified from a homogenised soil volume equivalent to the top soil layers. Results from first test experiments and current developments are reported.

  20. Effects of PV Module Soiling on Glass Surface Resistance and Potential-Induced Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter; Button, Patrick; Hendrickson, Alex; Spataru, Sergiu; Glick, Stephen

    2015-06-14

    The goals of the project were: Determine applicability of transmission line method (TLM) to evaluate sheet resistance of soils on module glass;
    Evaluate various soils on glass for changes in surface resistance and their ability to promote potential-induced degradation with humidity (PID);
    Evaluate PID characteristics, rate, and leakage current increases on full-size mc-Si modules associated with a conductive soil on the surface.

  1. Compositional variations in In(0.5)Ga(0.5)N nanorods grown by molecular beam epitaxy.

    Science.gov (United States)

    Cherns, D; Webster, R F; Novikov, S V; Foxon, C T; Fischer, A M; Ponce, F A; Haigh, S J

    2014-05-30

    The composition of InxGa1 - xN nanorods grown by molecular beam epitaxy with nominal x = 0.5 has been mapped by electron microscopy using Z-contrast imaging and x-ray microanalysis. This shows a coherent and highly strained core-shell structure with a near-atomically sharp boundary between a Ga-rich shell (x ∼ 0.3) and an In-rich core (x ∼ 0.7), which itself has In- and Ga-rich platelets alternating along the growth axis. It is proposed that the shell and core regions are lateral and vertical growth sectors, with the core structure determined by spinodal decomposition.

  2. A COMPARATIVE STUDY OF INTRATHECAL HYPERBARIC 0.5% BUPIVACAINE VERSUS INTRATHECAL 0.5% ISOBARIC LEVOBUPIVACAINE

    Directory of Open Access Journals (Sweden)

    Kurmanadh K

    2016-09-01

    Full Text Available BACKGROUND Bupivacaine is a long-acting agent capable of producing prolonged anaesthesia and analgesia that can be prolonged even further by the addition of epinephrine. It is substantially more cardiotoxic than lidocaine. The cardiotoxicity of bupivacaine is cumulative and substantially greater than would be predicted by its LA potency. At least part of the cardiotoxicity of bupivacaine maybe mediated centrally because direct injection of small quantities of bupivacaine into the medulla can produce malignant ventricular arrhythmias. Bupivacaine-induced cardiotoxicity can be difficult to treat.[1] Levobupivacaine contains a single enantiomer of bupivacaine hydrochloride and is less cardiotoxic than bupivacaine. It is extensively metabolised with no unchanged drug detected in urine or faeces. Research results suggest that levobupivacaine is a suitable less toxic alternative to bupivacaine.[2] METHODS The study entitled “A Randomised Controlled Double-Blind Comparative Study of 0.5% Levobupivacaine vs. 0.5% Heavy Bupivacaine For Surgeries Below Umbilicus During Spinal Anaesthesia” for various procedures done in the Department of Anaesthesiology at Andhra Medical College at King George Hospital, Visakhapatnam, from November 2011 to October 2012. The study was undertaken after obtaining Hospital Ethics Committee clearance as well as written informed consent from all patients after explaining and reassuring about the spinal procedure. A total of 100 patients of both sexes scheduled for elective lower abdominal surgeries under spinal anaesthesia in the age group of 18 to 55 years and belonging to American Society of Anaesthesiologists (ASA Physical Status I and II were enrolled for the study. The enrolled patients were randomised to one of the two groups of equal-sized prospective, comparative study group using a double-blind protocol design Group B (n=50 received 3.0 mL volume of 0.5% hyperbaric bupivacaine intrathecally and Group L (n=50

  3. [Effects of soil crusts on surface hydrology in the semiarid Loess hilly area].

    Science.gov (United States)

    Wei, Wei; Wen, Zhi; Chen, Li-Ding; Chen, Jin; Wu, Dong-Ping

    2012-11-01

    Soil crusts are distributed extensively in the Chinese Loess Plateau and play key roles in surface hydrological processes. In this study, a typical loess hilly region in Anjiagou catchment, Dingxi city, Gansu province was selected as the study region, and soil crusts in the catchment were investigated. Then, the hydrological effect of soil crusts was studied by using multi-sampling and hydrological monitoring experiments. Several key results were shown as follows. Firstly, compared with bared soil without crust cover, soil crusts can greatly reduce the bulk density, improve the porosity of soil, and raise the holding capacity of soil moisture which ranges from 1.4 to 1.9 times of that of bared soil. Secondly, the role of soil crust on rainfall interception was very significant. Moss crust was found to be strongest on rainfall interception, followed by synantectic crusts and lichen crusts. Bared soil without covering crusts was poorest in resisting rainfall splash. Thirdly, hydrological simulation experiments indicate that soil crusts play a certain positive role in promoting the water infiltration capacity, and the mean infiltration rate of the crusted soil was 2 times higher than that of the no-crust covered soils. While the accumulated infiltrated water amounts was also far higher than that of the bared soil.

  4. Directional reflectance factors for monitoring spatial changes in soil surface structure and soil organic matter erosion in agricultural systems

    Science.gov (United States)

    Croft, H.; Anderson, K.

    2012-04-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of soil organic matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness (SSR), indicating that a soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Accurate, spatially-continuous measurements of SSR are therefore needed at a variety of spatial and temporal scales to understand the spatial nature of SOM erosion and deposition. Remotely-sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Previous work has demonstrated the ability of directional reflectance factors to monitor soil crusting within a controlled laboratory experiment, due to changes in the levels of self-shadowing effects by soil aggregates. However, further research is needed to test this approach in situ, where other soil variables may affect measured reflectance factors and to investigate the use of directional reflectance factors for monitoring soil erosion processes. This experiment assesses the potential of using directional reflectance factors to monitor changes in SSR, aggregate stability and soil organic carbon (SOC) content for two agricultural conditions. Five soil plots representing tilled and seedbed soils were subjected to different durations of natural rainfall, producing a range of different levels of SSR. Directional reflectance factors were measured concomitantly with sampling for soil structural and biochemical tests at each soil plot. Soil samples were taken to measure aggregate stability (wet sieving), SOC (loss on ignition) and soil moisture (gravimetric method). SSM

  5. Heterogeneity of soil surface temperature induced by xerophytic shrub in a revegetated desert ecosystem, northwestern China

    Indian Academy of Sciences (India)

    Ya-Feng Zhang; Xin-Ping Wang; Yan-Xia PAN; Rui Hu; Hao Zhang

    2013-06-01

    Variation characteristics of the soil surface temperature induced by shrub canopy greatly affects the nearsurface biological and biochemical processes in desert ecosystems. However, information regarding the effects of shrub upon the heterogeneity of soil surface temperature is scarce. Here we aimed to characterize the effects of shrub (Caragana korshinskii) canopy on the soil surface temperature heterogeneity at areas under shrub canopy and the neighbouring bare ground. Diurnal variations of soil surface temperature were measured at areas adjacent to the shrub base (ASB), beneath the midcanopy (BMC), and in the bare intershrub spaces (BIS) at the eastern, southern, western and northern aspects of shrub, respectively. Results indicated that diurnal mean soil surface temperature under the C. korshinskii canopy (ASB and BMC) was significantly lower than in the BIS, with the highest in the BIS, followed by the BMC and ASB. The diurnal maximum and diurnal variations of soil surface temperatures under canopy vary strongly with different aspects of shrub with the diurnal variation in solar altitude, which could be used as cues to detect safe sites for under-canopy biota. A significant empirical linear relationship was found between soil surface temperature and solar altitude, suggesting an empirical predicator that solar altitude can serve for soil surface temperature. Lower soil surface temperatures under the canopy than in the bare intershrub spaces imply that shrubs canopy play a role of ‘cool islands’ in the daytime in terms of soil surface temperature during hot summer months in the desert ecosystems characterized by a mosaic of sparse vegetation and bare ground.

  6. Soil heat flux and day time surface energy balance closure at astronomical observatory, Thiruvananthapuram, south Kerala

    Indian Academy of Sciences (India)

    M S Roxy; V B Sumithranand; G Renuka

    2014-06-01

    Soil heat flux is an important input component of surface energy balance. Estimates of soil heat flux were made in the year 2008 using soil temperature data at Astronomical Observatory, Thiruvananthapuram, south Kerala. Hourly values of soil heat flux from 00 to 24 LST are presented for selected days typical of the winter, pre-monsoon, SW monsoon and NE monsoon seasons. The diurnal variation is characterized by a cross-over from negative to positive values at 0700 h, occurrence of maximum around noon and return to negative values in the late evening. The energy storage term for the soil layer 0–0.05 m is calculated and the ground heat flux * is estimated in all seasons. Daytime surface energy balance at the surface on wet and dry seasons is investigated. The average Bowen’s ratio during the wet and dry seasons were 0.541 and 0.515, respectively indicating that considerable evaporation takes place at the surface. The separate energy balance components were examined and the mean surface energy balance closure was found to be 0.742 and 0.795 for wet and dry seasons, respectively. When a new method that accounts for both soil thermal conduction and soil thermal convection was adopted to calculate the surface heat flux, the energy balance closure was found to be improved. Thus on the land surface under study, the soil vertical water movement is significant.

  7. Ethylene production by ODHE in catalytically modified Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ) membrane reactors.

    Science.gov (United States)

    Lobera, M Pilar; Escolástico, Sonia; Garcia-Fayos, Julio; Serra, José M

    2012-08-01

    Process intensification by the integration of membranes and high-temperature reactors offers several advantages with regard to conventional process schemes, that is, energy saving, safe operation, reduced plant/unit size, and higher process performance, for example, higher productivity, catalytic activity, selectivity, or stability. We present the study of oxidative dehydrogenation of ethane at 850 °C on a catalytic membrane reactor based on a mixed ionic-electronic conducting membrane. The surface of the membrane made of Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ) has been activated by using different porous catalytic layers based on perovskites. The layer was deposited by screen printing, and the porosity and thickness was studied for the catalyst composition. The different catalyst formulations are based on partial substitution of A- and B-site atoms of doped strontium ferrite/cobaltites (A(0.6)Sr(0.4)Co(0.5)Fe(0.5)O(3-δ) and Ba(0.6)Sr(0.4)BO(3-δ)) and were synthesized by an ethylenediaminetetraacetic acid-citrate complexation route. The use of a disk-shaped membrane in the reactor enabled the direct contact of gaseous oxygen and hydrocarbons to be avoided, and thus, the ethylene content increased. High ethylene yields (up to ≈81 %) were obtained by using a catalytic coating based on Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ), which included macropores produced by the addition of graphite platelets into the screen-printing ink. The promising catalytic results obtained with this catalytically modified membrane reactor are attributed to the combination of 1) the high activity, as a result of the high temperature and oxygen species diffusing through the membrane; 2) the control of oxygen dosing and the low concentration of molecules in the gas phase; and 3) suitable fluid dynamics, which enables appropriate feed contact with the membrane and the rapid removal of products.

  8. Using SMOS brightness temperature and derived surface-soil moisture to characterize surface conditions and validate land surface models.

    Science.gov (United States)

    Polcher, Jan; Barella-Ortiz, Anaïs; Piles, Maria; Gelati, Emiliano; de Rosnay, Patricia

    2017-04-01

    The SMOS satellite, operated by ESA, observes the surface in the L-band. On continental surface these observations are sensitive to moisture and in particular surface-soil moisture (SSM). In this presentation we will explore how the observations of this satellite can be exploited over the Iberian Peninsula by comparing its results with two land surface models : ORCHIDEE and HTESSEL. Measured and modelled brightness temperatures show a good agreement in their temporal evolution, but their spatial structures are not consistent. An empirical orthogonal function analysis of the brightness temperature's error identifies a dominant structure over the south-west of the Iberian Peninsula which evolves during the year and is maximum in autumn and winter. Hypotheses concerning forcing-induced biases and assumptions made in the radiative transfer model are analysed to explain this inconsistency, but no candidate is found to be responsible for the weak spatial correlations. The analysis of spatial inconsistencies between modelled and measured TBs is important, as these can affect the estimation of geophysical variables and TB assimilation in operational models, as well as result in misleading validation studies. When comparing the surface-soil moisture of the models with the product derived operationally by ESA from SMOS observations similar results are found. The spatial correlation over the IP between SMOS and ORCHIDEE SSM estimates is poor (ρ 0.3). A single value decomposition (SVD) analysis of rainfall and SSM shows that the co-varying patterns of these variables are in reasonable agreement between both products. Moreover the first three SVD soil moisture patterns explain over 80% of the SSM variance simulated by the model while the explained fraction is only 52% of the remotely sensed values. These results suggest that the rainfall-driven soil moisture variability may not account for the poor spatial correlation between SMOS and ORCHIDEE products. Other reasons have to

  9. Parasitic contamination of surface and deep soil in different areas of Sari in north of Iran

    Directory of Open Access Journals (Sweden)

    Hajar Ziaei Hezarjaribi

    2016-10-01

    Full Text Available Objective: To study the parasitic contamination of soil in selected areas of Sari, north of Iran. Methods: A cross-sectional study was conducted to identify all available parasites in surface and deep soil. In this study 580 soil samples (278 deep soil and 302 topsoil samples from 21 different locations were collected from pathways, parks, greenhouses, estates around the city, cemetery, main squares, farmlands, fenced gardens and seashores. Depending on the soil type, two samples were prepared, from surface and deep soil at the depth of 3 to 5 cm. After performing various stages of preparation, including cleaning and washing, smoothing and flotation, parasitic elements were examined microscopically and quantitative parasite counting was done using a McMaster slide. Results: The results showed that the highest rate of parasitic contamination was related to nematodes larvae (26.11%. Other contaminants such as Entamoeba and Acanthamoeba cysts, vacuolization Blastocystis hominis form, oocyte containing sporocysts, Toxascaris eggs, nematoda larvae, Hymenolepis eggs, Ascaris eggs, Fasciola eggs, hookworm eggs, Toxocara eggs, insects' larvae and other ciliated and flagellated organisms were also observed. The results of this study showed that the highest contamination was found in public garden (25.80% both in surface (29.30% and in deep soil (21.12%, while the lowest level of contamination was observed in seashore surface soil (4.90%. Conclusions: The results showed that soil can provide a potential medium for the spread of soil transmitted parasitic diseases in the environment; therefore, preventive programs are needed.

  10. Organic marker compounds for surface soil and fugitive dust from open lot dairies and cattle feedlots

    Science.gov (United States)

    Rogge, Wolfgang F.; Medeiros, Patricia M.; Simoneit, Bernd R. T.

    Fugitive dust emissions from cattle feedlots and open lot dairies are substantial. In order to determine the contribution of intensive cattle operations on ambient PM levels, more knowledge besides the elemental composition is necessary in order to distinguish between airborne PM from nearby agricultural fields, barren lands, or dirt roads. Here, as part of the San Joaquin Valley Fugitive Dust Characterization Study, surface soil samples collected from feedlots and open lot dairy farms are investigated for potential source specific molecular marker compounds. More than 100 organic compounds were quantified including: n-alkanes, n-alkanoic acids, n-alkenoic acids, n-alkanols, n-alkanals, n-alkan-2-ones, steroids, triterpenoids, isoprenoids, and tocopherols (vitamin E) and metabolites. Biohydrogenation of plant lipids and sterols in the rumen results in distinctive alteration products. Animal and plant derived steroids are most abundant. Here, it is shown that 5 β-stigmastanol and epi-5 β-stigmastanol, two biohydrogenation products of sitosterol and stigmasterol, are the most distinctive molecular marker compounds. While stearic (C 18) and palmitic (C 16) acids are as individual compounds not source specific, biohydrogenation of the more abundant C 18 unsaturated fatty acids, causes the ratio of C 18/C 16 fatty acids to shift from below 0.5 for vegetation to an average of 3.0±0.7. Consequently, the C 18/C 16 fatty acid ratio is unique and can be used as well in source apportionment studies.

  11. Temporal Dynamics of Soil Moisture Variability at the Landscape Scale: Implications for Land Surface Models.

    Science.gov (United States)

    Montaldo, N.; Albertson, J. D.

    2001-12-01

    Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends directly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, microbial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances affect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a conservation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spatial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calculate land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions using the proposed soil moisture

  12. Temporal Dynamics of Soil Moisture Variability: Implications For Land Surface Models

    Science.gov (United States)

    Montaldo, N.; Albertson, J. D.

    Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends di- rectly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, mi- crobial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances af- fect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a con- servation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spa- tial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calcu- late land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions us- ing the proposed

  13. Leaching and Redistribution of Nutrients in Surface Layer of Red Soils in Southeast China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The leaching and redistribution of nutrients in the surface layer of 4 types of red soils in Southeast China were studied with a lysimeter experiment under field conditions. Results showed that the leaching concentrated in the rainy season (from April to June). Generally, the leaching of soil nutrients from the surface layer of red soils was in the order of Ca > Mg > K > NO3-N. In fertilization treatment, the total amount of soil nutrients leached out of the surface layer in a red soil derived from granite was the highest in all soils. The uptake by grass decreased the leaching of fertilizer ions in surface layer, particularly for NO3-N. Soil total N and exchangeable K, Ca and Mg in the surface layer decreased with leaching and grass uptake during the 2 years without new fertilization of urea, Ca(H2PO4)2, KCl, CaCO3 and MgCO3. Ca moved from the application layer (0~5 cm) of fertilizer and accumulated in the 10~30 cm depth in the soils studied except that derived from Quaternary red clay. The deficiency of soil exchangeable K will become a serious degradation process facing the Southeast China.

  14. Element concentrations in surface soils of the Coconino Plateau, Grand Canyon region, Coconino County, Arizona

    Science.gov (United States)

    Van Gosen, Bradley S.

    2016-09-15

    This report provides the geochemical analyses of a large set of background soils collected from the surface of the Coconino Plateau in northern Arizona. More than 700 soil samples were collected at 46 widespread areas, sampled from sites that appear unaffected by mineralization and (or) anthropogenic contamination. The soils were analyzed for 47 elements, thereby providing data on metal concentrations in soils representative of the plateau. These background concentrations can be used, for instance, for comparison to metal concentrations found in soils potentially affected by natural and anthropogenic influences on the Coconino Plateau in the Grand Canyon region of Arizona.The soil sampling survey revealed low concentrations for the metals most commonly of environmental concern, such as arsenic, cobalt, chromium, copper, mercury, manganese, molybdenum, lead, uranium, vanadium, and zinc. For example, the median concentrations of the metals in soils of the Coconino Plateau were found to be comparable to the mean values previously reported for soils of the western United States.

  15. The Soil Characteristic Curve at Low Water Contents: Relations to Specific Surface Area and Texture

    DEFF Research Database (Denmark)

    Resurreccion, Augustus; Møldrup, Per; Schjønning, Per;

    Accurate description of the soil-water retention curve (SWRC) at low water contents is important for simulating water dynamics, plant-water relations, and microbial processes in surface soil. Soil-water retention at soil-water matric potential of less than -10 MPa, where adsorptive forces dominate...... that measurements by traditional pressure plate apparatus generally overestimated water contents at -1.5 MPa (plant wilting point). The 41 soils were classified into four textural classes based on the so-called Dexter index n (= CL/OC), and the Tuller-Or (TO) general scaling model describing the water film...... thickness at a given soil-water matric potential (low organic soils with n > 10, the estimated SA from the dry soil-water retention was in good agreement with the SA measured using ethylene glycol monoethyl ether (SA_EGME). A strong relationship between the ratio...

  16. Ectomycorrhizal Influence on Particle Size, Surface Structure, Mineral Crystallinity, Functional Groups, and Elemental Composition of Soil Colloids from Different Soil Origins

    Directory of Open Access Journals (Sweden)

    Yanhong Li

    2013-01-01

    Full Text Available Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus and soil colloids from dark brown forest soil (a good loam and saline-alkali soil (heavily degraded soil, we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P>0.05. These increased the amount of variable functional groups (O–H stretching and bending, C–H stretching, C=O stretching, etc. by 3–26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz by 40–300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12–35% decreases in most functional groups, 15–55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P<0.05. These different responses sharply decreased element ratios (C : O, C : N, and C : Si in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil.

  17. Ectomycorrhizal influence on particle size, surface structure, mineral crystallinity, functional groups, and elemental composition of soil colloids from different soil origins.

    Science.gov (United States)

    Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang

    2013-01-01

    Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O-H stretching and bending, C-H stretching, C=O stretching, etc.) by 3-26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40-300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12-35% decreases in most functional groups, 15-55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil.

  18. Effective Saturated Hydraulic Conductivity for Representing Field-Scale Infiltration and Surface Soil Moisture in Heterogeneous Unsaturated Soils Subjected to Rainfall Events

    Directory of Open Access Journals (Sweden)

    Richa Ojha

    2017-02-01

    Full Text Available Spatial heterogeneity in soil properties has been a challenge for providing field-scale estimates of infiltration rates and surface soil moisture content over natural fields. In this study, we develop analytical expressions for effective saturated hydraulic conductivity for use with the Green-Ampt model to describe field-scale infiltration rates and evolution of surface soil moisture over unsaturated fields subjected to a rainfall event. The heterogeneity in soil properties is described by a log-normal distribution for surface saturated hydraulic conductivity. Comparisons between field-scale numerical and analytical simulation results for water movement in heterogeneous unsaturated soils show that the proposed expressions reproduce the evolution of surface soil moisture and infiltration rate with time. The analytical expressions hold promise for describing mean field infiltration rates and surface soil moisture evolution at field-scale over sandy loam and loamy sand soils.

  19. On the Comparison of the Global Surface Soil Moisture product and Land Surface Modeling

    Science.gov (United States)

    Delorme, B., Jr.; Ottlé, C.; Peylin, P.; Polcher, J.

    2016-12-01

    Thanks to its large spatio-temporal coverage, the new ESA CCI multi-instruments dataset offers a good opportunity to assess and improve land surface models parametrization. In this study, the ESA CCI surface soil moisture (SSM) combined product (v2.2) has been compared to the simulated top first layers of the ORCHIDEE LSM (the continental part of the IPSL earth system model), in order to evaluate its potential of improvements with data assimilation techniques. The ambition of the work was to develop a comprehensive comparison methodology by analyzing simultaneously the temporal and spatial structures of both datasets. We analyzed the SSM synoptic, seasonal, and inter-annual variations by decomposing the signals into fast and slow components. ORCHIDEE was shown to adequately reproduce the observed SSM dynamics in terms of temporal correlation. However, these correlation scores are supposed to be strongly influenced by SSM seasonal variability and the quality of the model input forcing. Autocorrelation and spectral analyses brought out disagreements in the temporal inertia of the upper soil moisture reservoirs. By linking our results to land cover maps, we found that ORCHIDEE is more dependent on rainfall events compared to the observations in regions with sparse vegetation cover. These diflerences might be due to a wrong partition of rainfall between soil evaporation, transpiration, runofl and drainage in ORCHIDEE. To refine this analysis, a single value decomposition (SVD) of the co-variability between rainfall provided by WFDEI and soil moisture was pursued over Central Europe and South Africa. It showed that spatio-temporal co-varying patterns between ORCHIDEE and rainfall and the ESA-CCI product and rainfall are in relatively good agreement. However, the leading SVD pattern, which exhibits a strong annual cycle and explains the same portion of covariance for both datasets, explains a much larger fraction of variance for ORCHIDEE than for the ESA-CCI product

  20. Incorporation of water vapor transfer in the JULES land surface model: Implications for key soil variables and land surface fluxes

    Science.gov (United States)

    Garcia Gonzalez, Raquel; Verhoef, Anne; Luigi Vidale, Pier; Braud, Isabelle

    2012-05-01

    This study focuses on the mechanisms underlying water and heat transfer in upper soil layers, and their effects on soil physical prognostic variables and the individual components of the energy balance. The skill of the JULES (Joint UK Environment Simulator) land surface model (LSM) to simulate key soil variables, such as soil moisture content and surface temperature, and fluxes such as evaporation, is investigated. The Richards equation for soil water transfer, as used in most LSMs, was updated by incorporating isothermal and thermal water vapor transfer. The model was tested for three sites representative of semiarid and temperate arid climates: the Jornada site (New Mexico, USA), Griffith site (Australia), and Audubon site (Arizona, USA). Water vapor flux was found to contribute significantly to the water and heat transfer in the upper soil layers. This was mainly due to isothermal vapor diffusion; thermal vapor flux also played a role at the Jornada site just after rainfall events. Inclusion of water vapor flux had an effect on the diurnal evolution of evaporation, soil moisture content, and surface temperature. The incorporation of additional processes, such as water vapor flux among others, into LSMs may improve the coupling between the upper soil layers and the atmosphere, which in turn could increase the reliability of weather and climate predictions.

  1. Cone model for two surface foundations on layered soil

    Institute of Scientific and Technical Information of China (English)

    Chen Wenhua

    2006-01-01

    In this paper, the cone model is applied to the vibration analysis of two foundations on a layered soil half space. In the analysis, the total stress field in the subsoil is divided into the free-field and the scattering field. Seed's simplified method is adopted for the free-field analysis,while the cone model is proposed for analyzing the dynamic scattering stress wave field.The shear stress field and the compressive stress field in the layered stratum with two scattering sources are calculated by shear cone and compressive cone, respectively. Furthermore, the stress fields in the subsoil with two foundations are divided into six zones, and the P wave and S wave are analyzed in each zone. Numerical results are provided to illustrate features of the added stress field for two surface foundations under vertical and horizontal sinusoidal force excitation. The proposed cone model may be useful in handling some of the complex problems associated with multi-scattering sources.

  2. Effect of metal doping into Ce0.5Zr0.5O2 on catalytic activity of MnOx/Ce0.5-xZr0.5-xM0.2xOy/Al2O3 for benzene combustion

    Institute of Scientific and Technical Information of China (English)

    YAN Shenghui; WANG Jianli; ZHONG Junbo; CHEN Yaoqiang; LIU Zhimin; CAO Hongyan; GONG Maochu

    2008-01-01

    The research investigated the effect of doping two metals separately or together into Ce0.5Zr0.5O2 on the catalytic activity of MnOx/Ce0.5-xZr0.5-xM0.2xOy/Al2O3 (M=Y, Mn, Y and Mn) for catalytic combustion of benzene. The prepared catalysts were characterized by X-ray diffraction (XRD), surface area analysis, oxygen storage capacity (OSC), and H2-temperature programmed reduction (H2-TPR). Cata-lytic test was performed on a conventional fixed bed flow reactor. The characterization results revealed that Y and Mn ions entered into the ceria-zirconia mixed oxides framework, which improved the textural properties and greatly promoted the MnOx dispersion on the support surface. The complete conversion temperature of benzene on MnOx/Ce0.4Zr0.4Y0.1Mn0.1Oy/Al2O3 was 563 K, and the selectivity of carbon dioxides was 99%. This catalyst could be applied in a wide range of GHSV and wide concentration condition, showing great potential for application.

  3. Synthesis of nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} by absorption of ammonia into water-in-oil microemulsion in a rotor–stator reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingwen; Wang, Hongrun; Arowo, Moses; Sun, Baochang, E-mail: sunbc@mail.buct.edu.cn; Chen, Jianfeng; Shao, Lei, E-mail: shaol@mail.buct.edu.cn [Beijing University of Chemical Technology, State Key Laboratory of Organic–Inorganic Composites (China)

    2015-01-15

    A gas-microemulsion reaction precipitation method was employed to prepare nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} by absorption of NH{sub 3} into water-in-oil (W/O) microemulsion in a rotor–stator reactor . The effects of different operating conditions including final pH of the microemulsion, reaction temperature, initial Ce{sup 3+} and Zr{sup 4+} concentration, rotation speed, and gas–liquid volumetric ratio were investigated. Nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} with an average diameter of about 5.5 nm, a specific surface area of 215.6 m{sup 2}/g and a size distribution of 4–8 nm was obtained under the optimum operating conditions. The as-prepared nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} was loaded with Au to prepare nano-Au/Ce{sub 0.5}Zr{sub 0.5}O{sub 2} catalyst which was subsequently used for CO oxidation test. CO conversion rate reached 100 % at room temperature, indicating high catalytic activity of the nano-Au/Ce{sub 0.5}Zr{sub 0.5}O{sub 2} catalyst.

  4. MOCVD-derived multilayer Gd0.5Y0.5Ba2Cu3O7-δ films based on a novel heating method

    Science.gov (United States)

    Zhao, Ruipeng; Zhang, Fei; Liu, Qing; Xia, Yudong; Lu, Yuming; Cai, Chuanbing; Xiong, Jie; Tao, Bowan; Li, Yanrong

    2017-02-01

    Multilayer Gd0.5Y0.5Ba2Cu3O7-δ (GdYBCO) films have been deposited by the metal organic chemical vapor deposition process on LaMnO3/epitaxial MgO/ion beam assisted deposition (IBAD)-MgO/solution deposition planarization-Y2O3-buffered Hastelloy tapes. The buffered tapes were heated by the Joule effect after applying a heating current (I h) through the Hastelloy metal substrates. For this kind of current heating method, the heating energy is transmitted from the Hastelloy metal substrate to the oxide buffer layers, thereby the surface temperature of the tape will decline with an increase in the thickness of the deposited GdYBCO film if the heating current is unchanged. Therefore, the multilayer GdYBCO film structure where I h was adjusted for each layer was adopted to make sure that the surface temperature was always high enough to deposit purely c-axis oriented GdYBCO films. With this method, four-layer 1000 nm thick GdYBCO films were successfully prepared and the critical current (I c) reached 328 A cm-1 width (77 K, 0 T), corresponding to the critical current density (J c) of 3.28 MA cm-2 (77 K, 0 T).

  5. Soil particle tracing using RFID tags for elucidating the behavior of radiocesium on bare soil surfaces in Fukushima

    Science.gov (United States)

    Manome, Ryo; Onda, Yuichi; Patin, Jeremy; Stefani, Chiara; Yoshimura, Kazuya; Parsons, Tony; Cooper, James

    2014-05-01

    Radioactive materials are generally associated with soil particles in terrestrial environment and therefore the better understanding soil erosion processes is expected to improve the mitigation of radioactive risks. Spatial variability in soil erosion has been one of critical issues for soil erosion management. This study attempts to track soil particle movement on soil surfaces by employing Radio Frequency Identification (RFID) tags for the better understanding radiocesium behavior. A RFID tag contains a specific electronically identifier and it permits tracing its movement by reading the identifier. In this study, we made artificial soil particles by coating the RFID tags with cement material. The particle diameters of the artificial soil particles approximately ranged from 3 to 5 mm. The artificial soil particles were distributed in a reticular pattern on a soil erosion plot (bare soil surface, 22.13 m length × 5 m width, 4.4° slope) in Kawamata town where radiocesium deposited because of the Fukushima Dai-ichi power plant accident. After their distribution on October 2012, we had read the identifiers of RFID tags and recorded their locations on the plot for 14 times by September 2013. Moving distance (MD) was calculated based on the difference of the location for each sampling date. The topographical changes on the plot were also monitored with a laser scanner to describe interrill erosion and rill erosion area on 11occasions. Median MD is 10.8cm for all the observations. Median MD on interrill and rill erosion areas were 9.8 cm and 20.7 cm, respectively. Seasonal variation in MD was observed; an extremely large MD was found in May 2013, at the first reading after the winter season. This large MD after winter suggests that snowmelt runoff was the dominant process which transported the soil particles. Comparing the MD with the observed amounts of rainfall, sediment and runoff on the plot, significant positive correlation were found if the data of May, 2013

  6. Quantifying the effect of lichen and bryophyte cover on permafrost soil within a global land surface model

    Science.gov (United States)

    Porada, Philipp; Ekici, Altug; Beer, Christian

    2016-04-01

    Vegetation near the surface, such as bryophytes and lichens, has an insulating effect on the soil at high latitudes and it can therefore protect permafrost conditions. Warming due to climate change, however, may change the average surface coverage of bryophytes and lichens. This can result in permafrost thawing associated with a release of soil carbon to the atmosphere, which may lead to a positive feedback on atmospheric CO2. Thus, it is important to predict how the bryophyte and lichen cover at high latitudes will react to environmental change. However, current global land surface models so far contain mostly empirical approaches to represent bryophytes and lichens, which makes it impractical to predict their future state and function. For this reason, we integrate a process-based model of bryophyte and lichen growth into the global land surface model JSBACH. We explicitly represent dynamic thermal properties of the bryophyte and lichen cover and their relation to climate. Subsequently, we compare simulations with and without bryophyte and lichen cover to quantify the insulating effect. We estimate an annual average cooling effect of the bryophyte and lichen cover of 2.7 K on topsoil temperature for the northern high latitudes under current climate. Locally, the cooling may reach up to 5.7 K. Moreover, we show that neglecting dynamic properties of the bryophyte and lichen cover by using a simple, empirical scheme only results in an average cooling of around 0.5 K. This suggests that bryophytes and lichens have a significant impact on soil temperature in high-latitude ecosystems and also that a process-based description of their thermal properties is necessary for a realistic representation of the cooling effect.

  7. Homogenization of the soil surface following fire in semiarid grasslands

    Science.gov (United States)

    Carleton S. White

    2011-01-01

    Semiarid grasslands accumulate soil beneath plant "islands" that are raised above bare interspaces. This fine-scale variation in microtopographic relief is plant-induced and is increased with shrub establishment. Research found that fire-induced water repellency enhanced local-scale soil erosion that reduced variation in microtopographic relief, suggesting...

  8. Enhancing agricultural forecasting using SMOS surface soil moisture retrievals

    Science.gov (United States)

    With the onset of data availability from the ESA Soil Moisture and Ocean Salinity (SMOS) mission (Kerr and Levine, 2008) and the expected 2015 launch of the NASA Soil Moisture Active and Passive (SMAP) mission (Entekhabi et al., 2010), the next five years should see a significant expansion in our ab...

  9. Spectral reflectance of surface soils - A statistical analysis

    Science.gov (United States)

    Crouse, K. R.; Henninger, D. L.; Thompson, D. R.

    1983-01-01

    The relationship of the physical and chemical properties of soils to their spectral reflectance as measured at six wavebands of Thematic Mapper (TM) aboard NASA's Landsat-4 satellite was examined. The results of performing regressions of over 20 soil properties on the six TM bands indicated that organic matter, water, clay, cation exchange capacity, and calcium were the properties most readily predicted from TM data. The middle infrared bands, bands 5 and 7, were the best bands for predicting soil properties, and the near infrared band, band 4, was nearly as good. Clustering 234 soil samples on the TM bands and characterizing the clusters on the basis of soil properties revealed several clear relationships between properties and reflectance. Discriminant analysis found organic matter, fine sand, base saturation, sand, extractable acidity, and water to be significant in discriminating among clusters.

  10. Satellite remote sensing applications for surface soil moisture monitoring: A review

    Institute of Scientific and Technical Information of China (English)

    Lingli WANG; John J.QU

    2009-01-01

    Surface soil moisture is one of the crucial variables in hydrological processes, which influences the exchange of water and energy fluxes at the land surface/ atmosphere interface. Accurate estimate of the spatial and temporal variations of soil moisture is critical for numerous environmental studies. Recent technological advances in satellite remote sensing have shown that soil moisture can be measured by a variety of remote sensing techniques,each with its own strengths and weaknesses. This paper presents a comprehensive review of the progress in remote sensing of soil moisture, with focus on technique approaches for soil moisture estimation from optical,thermal, passive microwave, and active microwave measurements. The physical principles and the status of current retrieval methods are summarized. Limitations existing in current soil moisture estimation algorithms and key issues that have to be addressed in the near future are also discussed.

  11. Experimental study on the relation between the water content of surface soil and the acoustic wave

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to investigate the relation between the water content changing of surface soil and micro-quake recorded before earthquakes, we carried out a simulation experiment in laboratory. Its purpose is to explore whether the acoustic wave generated by micro-fracturing before earthquake are able to change water content of surface soil, so as to understand the relation between thermal anomaly in the remote sensing image got from the seismogenic area and the coming earthquake. The result of the experiment shows that when the acoustic wave enters into the surface soil the water content here increases on the background of decreasing due to natural evaporation. In the meantime, temperature here decreases.

  12. Horizontal Heat Impact of Urban Structures on the Surface Soil Layer and Its Diurnal Patterns under Different Micrometeorological Conditions

    Science.gov (United States)

    Zhou, Hongxuan; Hu, Dan; Wang, Xiaolin; Han, Fengsen; Li, Yuanzheng; Wu, Xiaogang; Ma, Shengli

    2016-01-01

    The temperature of the surface soil layer around different orientation walls was investigated horizontally along several construction-soil micro-gradients in Beijing, China. On a diurnal scale, similar fluctuating trends in T0 and T50 (temperature of surface soil layer, 0 and 0.5 m from the building baseline) adjacent to the external walls of buildings with the same orientation usually appeared under similar micrometeorological conditions. The difference between T0 and T50 (ΔT0-50) can be considered an indicator of the intensity of the horizontal heat effects: higher ΔT0-50 values correspond to greater intensities. The values of ΔT0-50 for south-, north-, east- and west-facing sides of buildings were highest on sunny days in summer and exhibited values of 6.61 K, 1.64 K, 5.93 K and 2.76 K, respectively. The scope of horizontal heat impacts (Sh) changed on a diurnal scale between zero and the maximum, which fluctuated with the micrometeorological conditions. The maximum values of Sh were 0.30, 0.15, 0.20 and 0.20 m for south-, north-, east-, and west-facing walls. The ΔT0-50 was related to solar radiation, horizontal heat flux, relative humidity, wind speed, soil moisture differences and air temperature; the relative importance of these factors was 36.22%, 31.80%, 19.19%, 2.67%, 3.68% and 6.44%, respectively.

  13. Corn Stover Impacts on Near-Surface Soil Properties of No-Till Corn In Ohio

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Canqui, H; Lal, Rattan; Post, W M.; Izaurralde, R Cesar C.; Owens, L B.

    2006-01-06

    Corn stover is a primary biofuel feedstock and its expanded use could help reduce reliance on fossil fuels and net CO2 emissions. Excessive stover removal may, however, negatively impact near-surface soil properties within a short period after removal. We assessed changes in soil crust strength, bulk density, and water content over a 1-yr period following a systematic removal or addition of stover from three no-till soils under corn in Ohio.

  14. Discontinuity in heat capacity of Fe0.5Co0.5(110) alloy thin films

    Science.gov (United States)

    Ramírez-Dámaso, G.; Castillo-Alvarado, F.-L.; Cruz-Torres, A.; Rójas-Hernández, E.

    2016-07-01

    In this work we calculate heat capacity of alloy thin films of FeCo on the surface of the plane (110), using three parameters, the concentration x(i), the lattice long range order parameter t(i) and the magnetic order parameter σ(i), being i the number of layers of the thin film. The formulations reported by Hill [1] in the context of small particles and Valenta's model [2] can be applied to the film structure when we treat a thin film as a system divided into subsystems equivalent to two-dimensional parallel layers. The FeCo bulk alloy is completely homogeneous while a thin film have spatial discontinuities in their surfaces. We consider three ferromagnetic thin films formed by 11, 15 and 19 layers in the Helmholtz's free energy, which is minimized applying their first partial derivatives with respect to chemical composition, long range order parameter and magnetic order parameter. We calculate internal energy and heat capacity as a function of temperature and we verify that have two jumps as are reported in literature for the bulk; there are many results of bulk or surface effects of FeCo, but no enough results about ferromagnetic FeCo thin films and this fact does this work interesting.

  15. Soil surface temperatures reveal moderation of the urban heat island effect by trees and shrubs.

    Science.gov (United States)

    Edmondson, J L; Stott, I; Davies, Z G; Gaston, K J; Leake, J R

    2016-09-19

    Urban areas are major contributors to air pollution and climate change, causing impacts on human health that are amplified by the microclimatological effects of buildings and grey infrastructure through the urban heat island (UHI) effect. Urban greenspaces may be important in reducing surface temperature extremes, but their effects have not been investigated at a city-wide scale. Across a mid-sized UK city we buried temperature loggers at the surface of greenspace soils at 100 sites, stratified by proximity to city centre, vegetation cover and land-use. Mean daily soil surface temperature over 11 months increased by 0.6 °C over the 5 km from the city outskirts to the centre. Trees and shrubs in non-domestic greenspace reduced mean maximum daily soil surface temperatures in the summer by 5.7 °C compared to herbaceous vegetation, but tended to maintain slightly higher temperatures in winter. Trees in domestic gardens, which tend to be smaller, were less effective at reducing summer soil surface temperatures. Our findings reveal that the UHI effects soil temperatures at a city-wide scale, and that in their moderating urban soil surface temperature extremes, trees and shrubs may help to reduce the adverse impacts of urbanization on microclimate, soil processes and human health.

  16. Density and stability of soil organic carbon beneath impervious surfaces in urban areas.

    Science.gov (United States)

    Wei, Zongqiang; Wu, Shaohua; Yan, Xiao; Zhou, Shenglu

    2014-01-01

    Installation of impervious surfaces in urban areas has attracted increasing attention due to its potential hazard to urban ecosystems. Urban soils are suggested to have robust carbon (C) sequestration capacity; however, the C stocks and dynamics in the soils covered by impervious surfaces that dominate urban areas are still not well characterized. We compared soil organic C (SOC) densities and their stabilities under impervious surface, determined by a 28-d incubation experiment, with those in open areas in Yixing City, China. The SOC density (0-20 cm) under impervious surfaces was, on average, 68% lower than that in open areas. Furthermore, there was a significantly (Psoils, whereas the correlation was not apparent for the impervious-covered soils, suggesting that the artificial soil sealing in urban areas decoupled the cycle of C and N. Cumulative CO2-C evolved during the 28-d incubation was lower from the impervious-covered soils than from the open soils, and agreed well with a first-order decay model (Ct = C1+C0(1-e-kt)). The model results indicated that the SOC underlying capped surfaces had weaker decomposability and lower turnover rate. Our results confirm the unique character of urban SOC, especially that beneath impervious surface, and suggest that scientific and management views on regional SOC assessment may need to consider the role of urban carbon stocks.

  17. Soil surface temperatures reveal moderation of the urban heat island effect by trees and shrubs

    Science.gov (United States)

    Edmondson, J. L.; Stott, I.; Davies, Z. G.; Gaston, K. J.; Leake, J. R.

    2016-09-01

    Urban areas are major contributors to air pollution and climate change, causing impacts on human health that are amplified by the microclimatological effects of buildings and grey infrastructure through the urban heat island (UHI) effect. Urban greenspaces may be important in reducing surface temperature extremes, but their effects have not been investigated at a city-wide scale. Across a mid-sized UK city we buried temperature loggers at the surface of greenspace soils at 100 sites, stratified by proximity to city centre, vegetation cover and land-use. Mean daily soil surface temperature over 11 months increased by 0.6 °C over the 5 km from the city outskirts to the centre. Trees and shrubs in non-domestic greenspace reduced mean maximum daily soil surface temperatures in the summer by 5.7 °C compared to herbaceous vegetation, but tended to maintain slightly higher temperatures in winter. Trees in domestic gardens, which tend to be smaller, were less effective at reducing summer soil surface temperatures. Our findings reveal that the UHI effects soil temperatures at a city-wide scale, and that in their moderating urban soil surface temperature extremes, trees and shrubs may help to reduce the adverse impacts of urbanization on microclimate, soil processes and human health.

  18. Carbon mineralization in surface and subsurface soils in a subtropical mixed forest in central China

    Science.gov (United States)

    Liu, F.; Tian, Q.

    2014-12-01

    About a half of soil carbon is stored in subsurface soil horizons, their dynamics have the potential to significantly affect carbon balancing in terrestrial ecosystems. However, the main factors regulating subsurface soil carbon mineralization are poorly understood. As affected by mountain humid monsoon, the subtropical mountains in central China has an annual precipitation of about 2000 mm, which causes strong leaching of ions and nutrition. The objectives of this study were to monitor subsurface soil carbon mineralization and to determine if it is affected by nutrient limitation. We collected soil samples (up to 1 m deep) at three locations in a small watershed with three soil layers (0-10 cm, 10-30 cm, below 30 cm). For the three layers, soil organic carbon (SOC) ranged from 35.8 to 94.4 mg g-1, total nitrogen ranged from 3.51 to 8.03 mg g-1, microbial biomass carbon (MBC) ranged from 170.6 to 718.4 μg g-1 soil. We measured carbon mineralization with the addition of N (100 μg N/g soil), P (50 μg P/g soil), and liable carbon (glucose labeled by 5 atom% 13C, at five levels: control, 10% MBC, 50% MBC, 100% MBC, 200% MBC). The addition of N and P had negligible effects on CO2 production in surface soil layers; in the deepest soil layer, the addition of N and P decreased CO2 production from 4.32 to 3.20 μg C g-1 soil carbon h-1. Glucose addition stimulated both surface and subsurface microbial mineralization of SOC, causing priming effects. With the increase of glucose addition rate from 10% to 200% MBC, the primed mineralization rate increased from 0.19 to 3.20 μg C g-1 soil carbon h-1 (fifth day of glucose addition). The magnitude of priming effect increased from 28% to 120% as soil layers go deep compare to the basal CO2 production (fifth day of 200% MBC glucose addition, basal CO2 production rate for the surface and the deepest soil was 11.17 and 2.88 μg C g-1 soil carbon h-1). These results suggested that the mineralization of subsurface carbon is more

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

    Science.gov (United States)

    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.

  20. Multiscale analysis of surface soil moisture dynamics in a mesoscale catchment utilizing an integrated ecohydrological model

    Science.gov (United States)

    Korres, W.; Reichenau, T. G.; Schneider, K.

    2012-12-01

    Soil moisture is one of the fundamental variables in hydrology, meteorology and agriculture, influencing the partitioning of solar energy into latent and sensible heat flux as well as the partitioning of precipitation into runoff and percolation. Numerous studies have shown that in addition to natural factors (rainfall, soil, topography etc.) agricultural management is one of the key drivers for spatio-temporal patterns of soil moisture in agricultural landscapes. Interactions between plant growth, soil hydrology and soil nitrogen transformation processes are modeled by using a dynamically coupled modeling approach. The process-based ecohydrological model components of the integrated decision support system DANUBIA are used to identify the important processes and feedbacks determining soil moisture patterns in agroecosystems. Integrative validation of plant growth and surface soil moisture dynamics serves as a basis for a spatially distributed modeling analysis of surface soil moisture patterns in the northern part of the Rur catchment (1100 sq km), Western Germany. An extensive three year dataset (2007-2009) of surface soil moisture-, plant- (LAI, organ specific biomass and N) and soil- (texture, N, C) measurements was collected. Plant measurements were carried out biweekly for winter wheat, maize, and sugar beet during the growing season. Soil moisture was measured with three FDR soil moisture stations. Meteorological data was measured with an eddy flux station. The results of the model validation showed a very good agreement between the modeled plant parameters (biomass, green LAI) and the measured parameters with values between 0.84 and 0.98 (Willmotts index of agreement). The modeled surface soil moisture (0 - 20 cm) showed also a very favorable agreement with the measurements for winter wheat and sugar beet with an RMSE between 1.68 and 3.45 Vol.-%. For maize, the RMSE was less favorable particularly in the 1.5 months prior to harvest. The modeled soil

  1. Soil surface moisture estimation over a semi-arid region using ENVISAT ASAR radar data for soil evaporation evaluation

    Directory of Open Access Journals (Sweden)

    M. Zribi

    2011-01-01

    Full Text Available The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring of moisture variability related to rainfall events, over areas in the "non-irrigated olive tree" class of land use. The developed approach is based on a simple linear relationship between soil moisture and the backscattered radar signal normalised at a reference incidence angle. The second process is proposed over wheat fields, using an analysis of moisture variability due to both rainfall and irrigation. A semi-empirical model, based on the water-cloud model for vegetation correction, is used to retrieve soil moisture from the radar signal. Moisture mapping is carried out over wheat fields, showing high variability between irrigated and non-irrigated wheat covers. This analysis is based on a large database, including both ENVISAT ASAR and simultaneously acquired ground-truth measurements (moisture, vegetation, roughness, during the 2008–2009 vegetation cycle. Finally, a semi-empirical approach is proposed in order to relate surface moisture to the difference between soil evaporation and the climate demand, as defined by the potential evaporation. Mapping of the soil evaporation is proposed.

  2. Organic matter composition of soil macropore surfaces under different agricultural management practices

    Science.gov (United States)

    Glæsner, Nadia; Leue, Marin; Magid, Jacob; Gerke, Horst H.

    2016-04-01

    Understanding the heterogeneous nature of soil, i.e. properties and processes occurring specifically at local scales is essential for best managing our soil resources for agricultural production. Examination of intact soil structures in order to obtain an increased understanding of how soil systems operate from small to large scale represents a large gap within soil science research. Dissolved chemicals, nutrients and particles are transported through the disturbed plow layer of agricultural soil, where after flow through the lower soil layers occur by preferential flow via macropores. Rapid movement of water through macropores limit the contact between the preferentially moving water and the surrounding soil matrix, therefore contact and exchange of solutes in the water is largely restricted to the surface area of the macropores. Organomineral complex coated surfaces control sorption and exchange properties of solutes, as well as availability of essential nutrients to plant roots and to the preferentially flowing water. DRIFT (Diffuse Reflectance infrared Fourier Transform) Mapping has been developed to examine composition of organic matter coated macropores. In this study macropore surfaces structures will be determined for organic matter composition using DRIFT from a long-term field experiment on waste application to agricultural soil (CRUCIAL, close to Copenhagen, Denmark). Parcels with 5 treatments; accelerated household waste, accelerated sewage sludge, accelerated cattle manure, NPK and unfertilized, will be examined in order to study whether agricultural management have an impact on the organic matter composition of intact structures.

  3. The effectiveness of surface liming in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem

    Science.gov (United States)

    Golos, Peter

    2016-04-01

    collected at >10 cm depth than the control. Mean soil pH at 0-10 cm was higher (>7.2) at all sites treated with lime compared to uncontaminated soil (5.5). At depths greater than 10 cm soil pH was 16 mg/kg in all contaminated soil samples compared to 0.5 mg/kg in control. High seedling mortality in contaminated site is attributed to low soil pH and elevated soil copper levels which inhibited plant root growth and hence access to soil water. While surface liming of soil increased soil pH ameliorating the effect of elevated soil copper, this was only effective in the top 10 cm due to low solubility of hydrated lime. To improve seedling survival lime will need to be incorporated into the contaminated soil profile to allow plants to access soil water at depth. This study highlights the importance of the need to assess the phytotoxic effects of soil contamination and the effectiveness of amelioration treatments and with proper reference to its ecological context. To improve the success of vegetation restoration of sites contaminated with acidic copper solution, lime needs to be incorporated into the contaminated soil profile to allow plant roots to access soil water at depth. This study highlights the importance of the need to assess the phytotoxic effects of soil contamination and the effectiveness of amelioration treatments and with proper reference to its ecological context.

  4. EFFECT OF SOIL TILLAGE AND PLANT RESIDUE ON SURFACE ROUGHNESS OF AN OXISOL UNDER SIMULATED RAIN

    Directory of Open Access Journals (Sweden)

    Elói Panachuki

    2015-02-01

    Full Text Available Surface roughness of the soil is formed by mechanical tillage and is also influenced by the kind and amount of plant residue, among other factors. Its persistence over time mainly depends on the fundamental characteristics of rain and soil type. However, few studies have been developed to evaluate these factors in Latossolos (Oxisols. In this study, we evaluated the effect of soil tillage and of amounts of plant residue on surface roughness of an Oxisol under simulated rain. Treatments consisted of the combination of the tillage systems of no-tillage (NT, conventional tillage (CT, and minimum tillage (MT with rates of plant residue of 0, 1, and 2 Mg ha-1 of oats (Avena strigosa Schreb and 0, 3, and 6 Mg ha-1 of maize (Zea mays L.. Seven simulated rains were applied on each experimental plot, with intensity of 60±2 mm h-1 and duration of 1 h at weekly intervals. The values of the random roughness index ranged from 2.94 to 17.71 mm in oats, and from 5.91 to 20.37 mm in maize, showing that CT and MT are effective in increasing soil surface roughness. It was seen that soil tillage operations carried out with the chisel plow and the leveling disk harrow are more effective in increasing soil roughness than those carried out with the heavy disk harrow and leveling disk harrow. The roughness index of the soil surface decreases exponentially with the increase in the rainfall volume applied under conditions of no tillage without soil cover, conventional tillage, and minimum tillage. The oat and maize crop residue present on the soil surface is effective in maintaining the roughness of the soil surface under no-tillage.

  5. Sorption of a triazol derivative by soils: importance of surface acidity

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The sorption of a triazol derivative, 1-(4-chlorophenyl)- 4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)penten-3-ol with a common name of S3307D, on fifteen soils and three H2O2-treated soils was investigated. The sorption isotherm for each untreated and treated soil was non-linear, and was best fitted to Freundlich sorption equation. Soils containing high amount of clay content or organic matter or both sorbed much higher amounts of the chemical than soils that had low contents of these soil constituents. H2O2-treated soils showed considerable sorptive affinity for S3307D. It was concluded that both organic matter and mineral fraction in natural soils contributed to the sorption of the basic compound. Sorption by the H2O2 treated soils increased as suspension pH decreased, but all suspension pHs exceeded the pKa of the compound by more than two units. This implies that organic base protonation can occur on surfaces of soil components, and surface acidity (exchangeable acidity ) is important in sorption process of the organic base rather than suspension pH.

  6. Residue determination and levels of glyphosate in surface waters, sediments and soils associated with oil palm plantation in Tasik Chini, Pahang, Malaysia

    Science.gov (United States)

    Mardiana-Jansar, K.; Ismail, B. S.

    2014-09-01

    Levels of glyphosate and its main metabolite were determined in surface water, soil and sediment samples from an oil palm plantation area located at Tasik Chini, Pahang, Malaysia. The optimization analytical method has been developed for the determination of glyphosate herbicide and its metabolite amino-methyl-phosphonic acid (AMPA) in surface waters to a level of 0.1μg/L, while in sediments and soils to a level of 0.5μg/g with a good linearity in the calibration range of 1-100μg/L. The procedure involves a pre-columnderivatization step with 9-fluorenyl-methyl-chloroformate (FMOC-Cl) yielding highly fluorescent derivatives of the analytes which can be determined by HPLC with fluorescence detection. In the field, levels of glyphosate in surface waters ranges from not detected to 1.0mg/L, while in soils and sediments were from not detected to 6.0mg/kg. For AMPA, the residues in surface waters were between not detected to 2.0mg/L, while in soil and sediment samples were from not detected to 5mg/kg. This variation of glyphosate and AMPA levels depended directly on time of pesticide application and the season.

  7. Spatial Distribution of Surface Soil Moisture in a Small Forested Catchment

    Science.gov (United States)

    Predicting the spatial distribution of soil moisture is an important hydrological question. We measured the spatial distribution of surface soil moisture (upper 6 cm) using an Amplitude Domain Reflectometry sensor at the plot scale (2 × 2 m) and small catchment scale (0.84 ha) in...

  8. Spatial Distribution of Surface Soil Moisture in a Small Forested Catchment

    Science.gov (United States)

    Predicting the spatial distribution of soil moisture is an important hydrological question. We measured the spatial distribution of surface soil moisture (upper 6 cm) using an Amplitude Domain Reflectometry sensor at the plot scale (2 × 2 m) and small catchment scale (0.84 ha) in...

  9. Cropping sequence and nitrogen fertilization impact on surface residue, soil carbon sequestration, and crop yields

    Science.gov (United States)

    Information is needed on the effect of management practices on soil C storage for obtaining C credit. The effects of tillage, cropping sequence, and N fertilization were evaluated on dryland crop and surface residue C and soil organic C (SOC) at the 0-120 cm depth in a Williams loam from 2006 to 201...

  10. Role of subsurface physics in the assimilation of surface soil moisture observations

    Science.gov (United States)

    Soil moisture controls the exchange of water and energy between the land surface and the atmosphere and exhibits memory that may be useful for climate prediction at monthly time scales. Though spatially distributed observations of soil moisture are increasingly becoming available from remotely sense...

  11. Effect of Vegetation Patterns on SAR derived Surface Soil Moisture Distribution

    Science.gov (United States)

    Koyama, C. N.; Schneider, K.

    2012-12-01

    Soil moisture can be regarded as one of the important life sustaining entities on our planet. Among its various functions, the first is probably to enable the growth of vegetation on the land surface. Apart from this, water stored in soils plays many other important roles in the global water (and energy) cycle. In the past decades, radar imaging has proven its potential to quantitatively estimate the near surface water content of soils at high spatial resolutions. The use of active microwave data to measure surface soil moisture requires the consideration of several factors like e.g. soil texture, surface roughness, and vegetation. Among these factors, the presence of a vegetation cover is perhaps the major impediment to accurate quantitative retrievals of soil moisture. On the one hand, the vegetation has a disturbing effect on the radar reflectivity and thus causes errors in the soil moisture retrieval which is generally based on theoretical or experimental relationships between the dielectric properties of the soil surface and the radar backscattering coefficient. On the other hand, the spatial distribution of vegetation with e.g. different crop types with different transpiration coefficients and different phenological development, etc, can cause large variations in the plant water consumption and thus has a significant impact on the soil moisture patterns. We have developed methods to estimate the amount of biomass for different crop types and the underlying surface soil water content directly from polarimetric L-band SAR images. While the horizontally-transmit horizontally-receive co-polarization (hh) is most sensitive towards the dielectric soil properties, the horizontally-transmit vertically-receive cross-polarization (hv) is much more sensitive towards the backscattering from the vegetation canopy. In addition the polarimetric observables entropy (H), alpha angle (α), and the total reflected power (span), all of which are highly affected by the canopy

  12. New methods to quantify NH3 volatilization from fertilized surface soil with urea

    Directory of Open Access Journals (Sweden)

    Ana Carolina Alves

    2011-02-01

    Full Text Available Gaseous N losses from soil are considerable, resulting mostly from ammonia volatilization linked to agricultural activities such as pasture fertilization. The use of simple and accessible measurement methods of such losses is fundamental in the evaluation of the N cycle in agricultural systems. The purpose of this study was to evaluate quantification methods of NH3 volatilization from fertilized surface soil with urea, with minimal influence on the volatilization processes. The greenhouse experiment was arranged in a completely randomized design with 13 treatments and five replications, with the following treatments: (1 Polyurethane foam (density 20 kg m-3 with phosphoric acid solution absorber (foam absorber, installed 1, 5, 10 and 20 cm above the soil surface; (2 Paper filter with sulfuric acid solution absorber (paper absorber, 1, 5, 10 and 20 cm above the soil surface; (3 Sulfuric acid solution absorber (1, 5 and 10 cm above the soil surface; (4 Semi-open static collector; (5 15N balance (control. The foam absorber placed 1 cm above the soil surface estimated the real daily rate of loss and accumulated loss of NH3N and proved efficient in capturing NH3 volatized from urea-treated soil. The estimates based on acid absorbers 1, 5 and 10 cm above the soil surface and paper absorbers 1 and 5 cm above the soil surface were only realistic for accumulated N-NH3 losses. Foam absorbers can be indicated to quantify accumulated and daily rates of NH3 volatilization losses similarly to an open static chamber, making calibration equations or correction factors unnecessary.

  13. Dielectric and Magnetic Properties of (1-x) CaTiO3--xNi0.5Zn0.5Fe2O4 Composite Ceramics

    Institute of Scientific and Technical Information of China (English)

    CHEN Chen; LIU Yin; WANG Chuanchuang; ZHU Yanyan; CHENG Qian; YI Zhiguo

    2016-01-01

    (1-x)CaTiO3-xNi0.5Zn0.5Fe2O4 (0x 1.0) composite ceramics were synthesized by a conventional solid state reaction method. The phase formation, microstructure, and dielectric and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, precision impedance analysis, and vibrating sample magnetometry, respectively. The results indicate that the composite ceramics are composed of both perovskite phase CaTiO3 and spinel phase Ni0.5Zn0.5Fe2O4. The maximal relative density for 0.5CaTiO3-0.5Ni0.5Zn0.5Fe2O4 composite ceramics reaches 97.8%, as it has been sintered at the temperature of 1260℃ for 3 h. Dielectric constant and loss tangent of (1-x)CaTiO3-xNi0.5Zn0.5Fe2O4 composite ceramics show dispersion in the low frequency range. Their phase transition temperature of the dielectric constant shifts to lower temperatures with the increase of Ni0.5Zn0.5Fe2O4 content. This phenomenon is attributed to that the phase transition temperature of CaTiO3 is higher than that of Ni0.5Zn0.5Fe2O4. The saturation magnetization of (1-x) CaTiO3-xNi0.5Zn0.5Fe2O4 composite ceramics increases with the Ni0.5Zn0.5Fe2O4 ferrite content.

  14. Influence of sub-surface irrigation on soil conditions and water irrigation efficiency in a cherry orchard in a hilly semi-arid area of northern China.

    Directory of Open Access Journals (Sweden)

    Gao Peng

    Full Text Available Sub-surface irrigation (SUI is a new water-saving irrigation technology. To explore the influence of SUI on soil conditions in a cherry orchard and its water-saving efficiency, experiments were conducted from 2009 to 2010 using both SUI and flood irrigation (FLI and different SUI quotas in hilly semi-arid area of northern China. The results demonstrated the following: 1 The bulk density of the soil under SUI was 6.8% lower than that of soil under FLI (P<0.01. The total soil porosity, capillary porosity and non-capillary porosity of soils using SUI were 11.7% (P<0.01, 8.7% (P<0.01 and 43.8% (P<0.01 higher than for soils using FLI. 2 The average soil temperatures at 0, 5, 10, 15 and 20 cm of soil depth using SUI were 1.7, 1.1, 0.7, 0.4 and 0.3°C higher than those for FLI, specifically, the differences between the surface soil layers were more significant. 3 Compared with FLI, the average water-saving efficiency of SUI was 55.6%, and SUI increased the irrigation productivity by 7.9-12.3 kg m(-3 ha(-1. 4 The soil moisture of different soil layers using SUI increased with increases in the irrigation quotas, and the soil moisture contents under SUI were significantly higher in the 0-20 cm layer and in the 21-50 cm layer than those under FLI (P<0.01. 5 The average yields of cherries under SUI with irrigation quotas of 80-320 m(3 ha(-1 were 8.7%-34.9% higher than those in soil with no irrigation (CK2. The average yields of cherries from soils using SUI were 4.5%-12.2% higher than using FLI. It is appropriate to irrigate 2-3 times with 230 m(3 ha(-1 per application using SUI in a year with normal rainfall. Our findings indicated that SUI could maintain the physical properties, greatly improve irrigation water use efficiency, and significantly increase fruit yields in hilly semi-arid areas of northern China.

  15. Electromigration of Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.5Ce-0.2Zn solder joints with Au/Ni(P)/Cu and Ag/Cu pads

    Energy Technology Data Exchange (ETDEWEB)

    Lin, H.-J., E-mail: HJLin@itri.org.t [Institute of Materials Science and Engineering, National Taiwan University, 1 Roosevelt St. Sec. 4, Taipei 106, Taiwan (China); Industrial Technology Research Institute, Mechanical and Systems Research Laboratories, Hsinchu 310, Taiwan (China); Lin, J.-S., E-mail: JohnnyLin@itri.org.t [Industrial Technology Research Institute, Mechanical and Systems Research Laboratories, Hsinchu 310, Taiwan (China); Department of Mechanical Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871 (Japan); Chuang, T.-H., E-mail: tunghan@ntu.edu.t [Institute of Materials Science and Engineering, National Taiwan University, 1 Roosevelt St. Sec. 4, Taipei 106, Taiwan (China)

    2009-11-13

    It has previously been established that adding 0.2 wt.% Zn into a Sn-3Ag-0.5Cu-0.5Ce alloy improves the mechanical properties and eliminates the problem of rapid whisker growth. However, no detailed studies have been conducted on electromigration behavior of Sn-3Ag-0.5Cu-0.5Ce-0.2Zn alloy. The electromigration damage in solder joints of Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.5Ce-0.2Zn with Ag/Cu pads and Au/Ni(P)/Cu pads was studied after current stressing at room temperature with an average current density of 3.1 x 10{sup 4} A/cm{sup 2}. With additions of 0.5 wt.% Ce and 0.2 wt.% Zn, the electromigration processes of Sn-Ag-Cu solder joints were accelerated due to refinement of the solder matrix when joint temperature was around 80 deg. C. Since Ni is more resistant than Cu to diffusion driven by electron flow, solder joints of both alloys (Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.5Ce-0.2Zn) with Au/Ni(P)/Cu pads possess longer current-stressing lifetimes than those with Ag/Cu pads.

  16. Predicting root zone soil moisture with soil properties and satellite near-surface moisture data across the conterminous United States

    Science.gov (United States)

    Baldwin, D.; Manfreda, S.; Keller, K.; Smithwick, E. A. H.

    2017-03-01

    Satellite-based near-surface (0-2 cm) soil moisture estimates have global coverage, but do not capture variations of soil moisture in the root zone (up to 100 cm depth) and may be biased with respect to ground-based soil moisture measurements. Here, we present an ensemble Kalman filter (EnKF) hydrologic data assimilation system that predicts bias in satellite soil moisture data to support the physically based Soil Moisture Analytical Relationship (SMAR) infiltration model, which estimates root zone soil moisture with satellite soil moisture data. The SMAR-EnKF model estimates a regional-scale bias parameter using available in situ data. The regional bias parameter is added to satellite soil moisture retrievals before their use in the SMAR model, and the bias parameter is updated continuously over time with the EnKF algorithm. In this study, the SMAR-EnKF assimilates in situ soil moisture at 43 Soil Climate Analysis Network (SCAN) monitoring locations across the conterminous U.S. Multivariate regression models are developed to estimate SMAR parameters using soil physical properties and the moderate resolution imaging spectroradiometer (MODIS) evapotranspiration data product as covariates. SMAR-EnKF root zone soil moisture predictions are in relatively close agreement with in situ observations when using optimal model parameters, with root mean square errors averaging 0.051 [cm3 cm-3] (standard error, s.e. = 0.005). The average root mean square error associated with a 20-fold cross-validation analysis with permuted SMAR parameter regression models increases moderately (0.082 [cm3 cm-3], s.e. = 0.004). The expected regional-scale satellite correction bias is negative in four out of six ecoregions studied (mean = -0.12 [-], s.e. = 0.002), excluding the Great Plains and Eastern Temperate Forests (0.053 [-], s.e. = 0.001). With its capability of estimating regional-scale satellite bias, the SMAR-EnKF system can predict root zone soil moisture over broad extents and has

  17. Uncertainties of seasonal surface climate predictions induced by soil moisture biases in the La Plata Basin

    Science.gov (United States)

    Sorensson, Anna; Berbery, E. Hugo

    2015-04-01

    This work examines the evolution of soil moisture initialization biases and their effects on seasonal forecasts depending on the season and vegetation type for a regional model over the La Plata Basin in South America. WRF/Noah model simulations covering multiple cases during a two-year period are designed to emphasize the conceptual nature of the simulations at the expense of statistical significance of the results. Analysis of the surface climate shows that the seasonal predictive skill is higher when the model is initialized during the wet season and the initial soil moisture differences are small. Large soil moisture biases introduce large surface temperature biases, particularly for Savanna, Grassland and Cropland vegetation covers at any time of the year, thus introducing uncertainty in the surface climate. Regions with Evergreen Broadleaf Forest have roots that extend to the deep layer whose moisture content affects the surface temperature through changes in the partitioning of the surface fluxes. The uncertainties of monthly maximum temperature can reach several degrees during the dry season in cases when: (a) the soil is much wetter in the reanalysis than in the WRF/Noah equilibrium soil moisture, and (b) the memory of the initial value is long due to scarce rainfall and low temperatures. This study suggests that responses of the atmosphere to soil moisture initialization depend on how the initial wet and dry conditions are defined, stressing the need to take into account the characteristics of a particular region and season when defining soil moisture initialization experiments.

  18. Soil, Groundwater, Surface Water, and Sediments of Kennedy Space Center, Florida: Background Chemical and Physical Characteristics

    Science.gov (United States)

    Shmalzer, Paul A.; Hensley, Melissa A.; Mota, Mario; Hall, Carlton R.; Dunlevy, Colleen A.

    2000-01-01

    This study documented background chemical composition of soils, groundwater, surface; water, and sediments of Kennedy Space Center. Two hundred soil samples were collected, 20 each in 10 soil classes. Fifty-one groundwater wells were installed in 4 subaquifers of the Surficial Aquifer and sampled; there were 24 shallow, 16 intermediate, and 11 deep wells. Forty surface water and sediment samples were collected in major watershed basins. All samples were away from sites of known contamination. Samples were analyzed for organochlorine pesticides, aroclors, chlorinated herbicides, polycyclic aromatic hydrocarbons (PAH), total metals, and other parameters. All aroclors (6) were below detection in all media. Some organochlorine pesticides were detected at very low frequencies in soil, sediment, and surface water. Chlorinated herbicides were detected at very low frequencies in soil and sediments. PAH occurred in low frequencies in soiL, shallow groundwater, surface water, and sediments. Concentrations of some metals differed among soil classes, with subaquifers and depths, and among watershed basins for surface water but not sediments. Most of the variation in metal concentrations was natural, but agriculture had increased Cr, Cu, Mn, and Zn.

  19. Controlling the sharpness of room-temperature metal-insulator transition in epitaxial Sm0.5Nd0.5NiO3 films

    Directory of Open Access Journals (Sweden)

    X. K. Lian

    2013-06-01

    Full Text Available Sm0.5Nd0.5NiO3 (SNNO films with metal-insulator transition (MIT at room-temperature (∼300 K have been grown on NdGaO3 (001 substrates by pulsed laser deposition. By modifying the parameters of oxygen pressure, substrate temperature, and film thickness, the role of oxygen vacancies and strain relaxation on the MIT of SNNO films was systematically analyzed. The strain status of the films was carefully characterized by means of high resolution x-ray diffraction. The results revealed that for the fully strained films (≤20 nm an increment of deposition oxygen pressure (and/or temperature would decrease the content of oxygen vacancies and Ni2+ in the films, leading to a sharp MIT. In contrast, the strain relaxation occurs in the thicker films (>20 nm despite an optimized oxygen pressure (temperature was adapted for the deposition, which results in an inferior transport property and surface morphology. Specifically, a broadening MIT and a doublet TMI was observed in the partially strained films, where one TMI kept a stable value around 300 K in analogues to that of fully strained film, and another one increased with the increment of the film thickness, reaching a highest value of 330 K. This might be induced by the coexistence of a fully strained part and a strain-relaxed portion in the thicker films that observed on high resolution X-ray reciprocal space mappings.

  20. Dielectric and magnetic studies of BaTi0.5Fe0.5O3 ceramic materials, synthesized by solid state sintering

    Science.gov (United States)

    Samuvel, K.; Ramachandran, K.

    2015-02-01

    A comparative study of the surface morphology, dielectric and magnetic properties of the BaTi0.5Fe0.5O3 (BTFO) ceramics materials. This has been carried out by synthesizing the samples in different routes. BTFO samples have shown single phased 12R type hexagonal structure with R 3m ‾ , P4mm space group. Interfacial effects on the dielectric properties of the samples have been understood by Cole-Cole plots in complex impedance and modulus formalism. It has been identified that huge dielectric constant (103-106) at lower frequencies is largely contributed by the heterogeneous electronic microstructure at the interfaces of grains. Modulus formalism has identified the effects of both grain and grain boundary microstructure on the dielectric properties, particularly in chemical routed samples. The order of grain boundary resistivity suggests the semiconductor/insulator class of the material. The grain boundary resistivity of the mechanical alloyed samples is remarkably lower than the solid state and chemical routed samples. Few samples have of the samples have exhibited signature of ferromagnetism at the room temperature.

  1. Oxygen separating membrane manufactured from Ba0.5Sr0.5Co0.8Fe0.2O3− perovskite-like material

    Indian Academy of Sciences (India)

    M Gromada; J Świder; J Trawczyński; M Stępień; M Wierzbicki

    2015-02-01

    The dense thin membrane for oxygen separation was manufactured from Ba0.5Sr0.5Co0.8Fe0.2O3− (BSCF) mixed oxide with perovskite-like structure prepared by the solid-state method. Properties of both powder and granulate (chemical and phase compositions, the specific surface area and the porosity) as well as sintered material (the apparent density, the apparent porosity, the water absorbability, the chemical composition, the crystallo-graphic structure and microstructure), that affect the process of ion oxygen permeation through membrane, were determined. Parameters influencing on usable properties of membranes viz., the bending strength and the coefficient of thermal expansion were assessed as well. Effect of the sintering temperature on membrane structure was evaluated. The elaborated fabrication procedure enables one to manufacture membrane, in which microstructure is characterized by the presence of big grains as well as decreased concentration of grain boundaries. Measurements of the oxygen permeation through BSCF membrane revealed that the highest oxygen flux reaching 2.6 cm3 O2/ (cm2 min) was obtained at 950°C under air and helium flows equal to 1 dm3 min−1.

  2. Structural and magnetic properties of size-controlled Mn0.5Zn0.5Fe2O4 nanoparticles and magnetic fluids

    Indian Academy of Sciences (India)

    Rucha Desai; Vipul Davariya; Kinnari Parekh; Ramesh V Upadhyay

    2009-10-01

    Mn0.5Zn0.5Fe2O4 ferrite nanoparticles with tunable Curie temperature and saturation magnetization are synthesized using hydrothermal co-precipitation method. Particle size is controlled in the range of 54 to 135 Å by pH and incubation time of the reaction. All the particles exhibit super-paramagnetic behaviour at room temperature. Langevin’s theory incorporating the interparticle interaction was used to fit the virgin curve of particle magnetization. The low-temperature magnetization follows Bloch spin wave theory. Curie temperature derived from magnetic thermogravimetric analysis shows that Curie temperature increases with increasing particle size. Using these particles magnetic fluid is synthesized and magnetic characterization is reported. The monolayer coating of surfactant on particle surface is confirmed using thermogravimetric measurement. The same technique can be extended to study the magnetic phase transition. The Curie temperature derived using this measurement complies with the low-temperature magnetic measurement. The room-temperature and high-temperature magnetization measurements are also studied for magnetic fluid systems. The magnetic parameters derived for fluid are in good agreement with those obtained for the particle system

  3. Mechanism of γ-irradiation induced phase transformations in nanocrystalline Mn0.5Zn0.5Fe2O4 ceramics

    Science.gov (United States)

    Jagadeesha Angadi, V.; Anupama, A. V.; Choudhary, Harish K.; Kumar, R.; Somashekarappa, H. M.; Mallappa, M.; Rudraswamy, B.; Sahoo, B.

    2017-02-01

    The structural, infrared absorption and magnetic property transformations in nanocrystalline Mn0.5Zn0.5Fe2O4 samples irradiated with different doses (0, 15, 25 and 50 kGy) of γ-irradiation were investigated in this work and a mechanism of phase transformation/decomposition is provided based on the metastable nature of the Mn-atoms in the spinel lattice. The nano-powder sample was prepared by solution combustion route and the pellets of the sample were exposed to γ-radiation. Up to a dose of 25 kGy of γ-radiation, the sample retained the single phase cubic spinel (Fd-3m) structure, but the disorder in the sample increased. On irradiating the sample with 50 kGy γ-radiation, the spinel phase decomposed into new stable phases such as α-Fe2O3 and ZnFe2O4 phases along with amorphous MnO phase, leading to a change in the surface morphology of the sample. Along with the structural transformations the magnetic properties deteriorated due to breakage of the ferrimagnetic order with higher doses of γ-irradiation. Our results are important for the understanding of the stability, durability and performance of the Mn-Zn ferrite based devices used in space applications.

  4. Anisotropic epitaxial strain effect on the charge-order phase of Nd0.5Sr0.5MnO3

    Science.gov (United States)

    Nakamura, Masao; Ogimoto, Yasushi; Tamaru, Hiroharu; Izumi, Makoto; Miyano, Kenjiro

    2005-03-01

    Strain effect in charge and orbital ordered state has been investigated for Nd0.5Sr0.5MnO3 thin films deposited on (100), (110), and (111)-oriented SrTiO3 (STO) substrates. Films on STO (001) and (111) substrates have monotonous temperature dependence for magnetic and transport properties showing no first-order phase transition. On the other hand, films on STO (110) show a clear ferromagnetic-antiferromagnetic and metal-insulator transition due to the onset of the charge and orbital order. Optical transmission spectra for the films on STO (110) show anisotry between the in-plane two axes. From the result, the orbital order plane of the film on STO (110) is deduced to be (100) or (010) plane, which lies out of the film surface. The reason for the difference in the magnetic and transport properties among the films on different substrate orientations, and why the clear metal-insulator transition occurs only on (110) substrates will be discussed.

  5. High-performance FeSe0.5Te0.5 thin films fabricated on less-well-textured flexible coated conductor templates

    Science.gov (United States)

    Xu, Zhongtang; Yuan, Pusheng; Ma, Yanwei; Cai, Chuanbing

    2017-03-01

    We report on the transport properties of FeSe0.5Te0.5 (FST) thin films fabricated on less-well-textured flexible coated conductor templates with LaMnO3 (LMO) as buffer layers using pulsed laser deposition. The LMO buffer layers exhibit large in-plane misalignment of ˜7.72°, which is unfavorable for cuprate-coated conductors due to the high grain boundaries. The FST thin films show a superconducting transition temperature of 16.8 K, higher than that of bulk materials due to the compressive strain between LMO and FST. Atomic force microscopy observations reveal that island-like features appear at the surfaces of both LMO and FST, confirming the island growth mode. A self-field transport critical-current density of up to 0.43 MA cm-2 at 4.2 K has been observed in FST thin films, which is much higher than that in powder-in-tube processed FST tapes. The films are capable of carrying current densities of over 105 A cm-2 in the whole applied magnetic field up to 9 T, showing great potential for high-field applications. The results indicate that, for FST, highly textured metal tapes are not needed to produce coated conductors with high performance, which is of great advantage over cuprate-coated conductors.

  6. Dielectric and magnetic studies of BaTi0.5Fe0.5O3 ceramic materials, synthesized by solid state sintering.

    Science.gov (United States)

    Samuvel, K; Ramachandran, K

    2015-02-05

    A comparative study of the surface morphology, dielectric and magnetic properties of the BaTi0.5Fe0.5O3 (BTFO) ceramics materials. This has been carried out by synthesizing the samples in different routes. BTFO samples have shown single phased 12R type hexagonal structure with R3m, P4mm space group. Interfacial effects on the dielectric properties of the samples have been understood by Cole-Cole plots in complex impedance and modulus formalism. It has been identified that huge dielectric constant (10(3)-10(6)) at lower frequencies is largely contributed by the heterogeneous electronic microstructure at the interfaces of grains. Modulus formalism has identified the effects of both grain and grain boundary microstructure on the dielectric properties, particularly in chemical routed samples. The order of grain boundary resistivity suggests the semiconductor/insulator class of the material. The grain boundary resistivity of the mechanical alloyed samples is remarkably lower than the solid state and chemical routed samples. Few samples have of the samples have exhibited signature of ferromagnetism at the room temperature.

  7. Studies on strain relaxation of La0.5Ba0.5MnO3 film by normal and grazing incidence X-ray diffraction

    Science.gov (United States)

    Wang, Haiou; Tan, Weishi; Liu, Hao; Cao, Mengxiong; Wang, Xingyu; Ma, Chunlin; Jia, Quanjie

    2017-03-01

    Perovskite manganite La0.5Ba0.5MnO3 (LBMO) films were deposited on (001)-oriented single-crystal SrTiO3 (STO) substrates by pulsed laser deposition. High-resolution X-ray diffraction and grazing incidence X-ray diffraction techniques were applied to characterize the crystal structure and lattice strain of LBMO films. The in-plane and out-of-plane growth orientations of LBMO films with respect to substrate surface have been studied. The epitaxial orientation relationship LBMO (001) [100] //STO (001) [100] exists at the LBMO/STO interface. The lattice strain of LBMO film begins to relax with the thickness of LBMO film up to 12 nm. When the thickness is further increased up to 43 nm, the film is in fully strain-relaxed state. Jahn-Teller strain plays an important role in LBMO/STO system. The mechanism for strain relaxation is in accordance with that of tetragonal distortion.

  8. Analysis of surface soil moisture patterns in agricultural landscapes using empirical orthogonal functions

    Directory of Open Access Journals (Sweden)

    W. Korres

    2009-08-01

    Full Text Available Soil moisture is one of the fundamental variables in hydrology, meteorology and agriculture. Nevertheless, its spatio-temporal patterns in agriculturally used landscapes affected by multiple natural (rainfall, soil, topography etc. and agronomic (fertilisation, soil management etc. factors are often not well known. The aim of this study is to determine the dominant factors governing the spatio-temporal patterns of surface soil moisture in a grassland and an arable land test site within the Rur catchment in Western Germany. Surface soil moisture (0–6 cm has been measured in an approx. 50×50 m grid at 14 and 17 dates (May 2007 to November 2008 in both test sites. To analyse spatio-temporal patterns of surface soil moisture, an Empirical Orthogonal Function (EOF analysis was applied and the results were correlated with parameters derived from topography, soil, vegetation and land management to connect the pattern to related factors and processes. For the grassland test site, the analysis results in one significant spatial structure (first EOF, which explains about 57.5% of the spatial variability connected to soil properties and topography. The weight of the first spatial EOF is stronger on wet days. The highest temporal variability can be found in locations with a high percentage of soil organic carbon (SOC. For the arable land test site, the analysis yields two significant spatial structures, the first EOF, explaining 38.4% of the spatial variability, shows a highly significant correlation to soil properties, namely soil texture. The second EOF, explaining 28.3% of the spatial variability, is connected to differences in land management. The soil moisture in the arable land test site varies more during dry and wet periods on locations with low porosity.

  9. Definition and experimental determination of a soil-water retention surface

    OpenAIRE

    Salager, Simon; El Youssoufi, Moulay Saïd; Saix, Christian

    2010-01-01

    International audience; This paper deals with the definition and determination methods of the soil-water retention surface (SWRS), which is the tool used to present the hydromechanical behaviour of soils to highlight both the effect of suction on the change in water and total volumes and the effect of deformation with respect to the water retention capability. An experimental method is introduced to determine the SWRS and applied to a clayey silty sand. The determination of this surface is ba...

  10. A Monte Carlo reflectance model for soil surfaces with three-dimensional structure

    Science.gov (United States)

    Cooper, K. D.; Smith, J. A.

    1985-01-01

    A Monte Carlo soil reflectance model has been developed to study the effect of macroscopic surface irregularities larger than the wavelength of incident flux. The model treats incoherent multiple scattering from Lambertian facets distributed on a periodic surface. Resulting bidirectional reflectance distribution functions are non-Lambertian and compare well with experimental trends reported in the literature. Examples showing the coupling of the Monte Carlo soil model to an adding bidirectional canopy of reflectance model are also given.

  11. Soil carbon sequestration by three perennial legume pastures is greater in deeper soil layers than in the surface soil

    Directory of Open Access Journals (Sweden)

    X.-K. Guan

    2015-07-01

    Full Text Available Soil organic carbon (SOC plays a vital role as both a sink for and source of atmospheric carbon. Revegetation of degraded arable land in China is expected to increase soil carbon sequestration, but the role of perennial legumes on soil carbon stocks in semiarid areas has not been quantified. In this study, we assessed the effect of alfalfa (Medicago sativa L. and two locally adapted forage legumes, bush clover (Lespedeza davurica S. and milk vetch (Astragalus adsurgens Pall. on the SOC concentration and SOC stock accumulated annually over a 2 m soil profile, and to estimate the long-term potential for SOC sequestration in the soil under the three forage legumes. The results showed that the concentration of SOC of the bare soil decreased slightly over the 7 years, while 7 years of legume growth substantially increased the concentration of SOC over the 0–2.0 m soil depth measured. Over the 7 year growth period the SOC stocks increased by 24.1, 19.9 and 14.6 Mg C ha−1 under the alfalfa, bush clover and milk vetch stands, respectively, and decreased by 4.2 Mg C ha−1 under bare soil. The sequestration of SOC in the 1–2 m depth of soil accounted for 79, 68 and 74 % of SOC sequestered through the upper 2 m of soil under alfalfa, bush clover and milk vetch, respectively. Conversion of arable land to perennial legume pasture resulted in a significant increase in SOC, particularly at soil depths below 1 m.

  12. L10 ordering at different stages of Fe0.5Pd0.5 epitaxial growth

    Science.gov (United States)

    Halley, D.; Auric, P.; Bayle-Guillemaud, P.; Gilles, B.; Marty, A.; Jalabert, D.

    2002-06-01

    FePd layers deposited by molecular beam epitaxy at 620 K on a (001) Pd buffer are investigated. At this growth temperature, an L10 structure is expected; we compare the crystal ordering at different depths in these thin films. 57Fe is used as a local probe at an atomic scale, located at different places within an equimolar FePd layer. The relationship between the alloy structure and the magnetic anisotropy of the films is investigated by Mossbauer spectroscopy. The possible decrease of the L10 ordering during growth is not observed. On the contrary, the quality of the L10 structure seems to improve, as confirmed by the low number of near-neighbors for iron atoms located on the top level of the alloy layer. Iron-rich clusters shaping into large vertical defects across the whole alloy layer are also observed; these clusters correspond to chemically disordered areas within the film. At the buffer interface, disordered, and dilute iron alloys (mean composition: Fe0.25 Pd0.75) with in-plane momenta are identified and explained assuming iron atom diffusion through about 1 nm thick Pd buffer, due to Pd segregation. Some iron rich aggregates could be the consequence of iron homocoordination or Pd surface segregation. The L10 structure is assumed to occur after about 1.7 nm alloy deposit.

  13. X-ray photoelectron spectroscopic study of direct reforming catalysts Ln0.5Sr0.5Ti0.5Mn0.5O3±d (Ln = La, Nd, and Sm) for high temperature-operating solid oxide fuel cell

    Science.gov (United States)

    Kim, Keunsoo; Jeong, Jihoon; Azad, Abul K.; Jin, Sang Beom; Kim, Jung Hyun

    2016-03-01

    Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln0.5Sr0.5Ti0.5Mn0.5O3±d (Ln = La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln0.5Sr0.5Ti0.5Mn0.5O3±d were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln0.5Sr0.5Ti0.5Mn0.5O3±d; Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln0.5Sr0.5Ti0.5Mn0.5O3±d, some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln0.5Sr0.5Ti0.5Mn0.5O3±d from the O 1s spectra; a high portion of lattice oxygen was observed in both Nd0.5Sr0.5Ti0.5Mn0.5O3±d (NSTM) and Sm0.5Sr0.5Ti0.5Mn0.5O3±d (SSTM). In various respects, NSTM and SSTM will be desirable reforming catalysts and anode candidates for high temperature solid oxide fuel cell.

  14. Prediction of Soil Erosion on Different Underlaying Surface in Construction Period of Xichang to Panzhihua Expressway

    Institute of Scientific and Technical Information of China (English)

    CHEN Tingfang; GUI Peng; CHEN Xingchang

    2007-01-01

    In order to investigate the behavior of soil erosion on the slope of the different underlaying surface during construction, the experiment with natural rainfall on Xichang-Panzhihua highway was conducted, to quantify the runoff and soil loss. The results show that: ①the main type of soil erosion is gully erosion, the amount of soil erosion caused by gully erosion is higher than that by surface erosion. ②The principal factor causing soil erosion on the slope of the embankment is individual amount of precipitation, the width of the embankment and rain intensity. ③ The principal factor causing soil erosion on the cutting slope is individual amount of precipitation, the width of the cutting slope and rain intensity. ④ The principal factor causing soil erosion on the slope of the dumped soil area is individual amount of precipitation, the width of the flat roof and rain intensity. There are well linear relationships between the amount of soil erosion and the principal factor, and their correlation coefficient are 0.935 7-0.999 8.

  15. Mapping Surface Soil Organic Carbon for Crop Fields with Remote Sensing

    Science.gov (United States)

    Chen, Feng; Kissel, David E.; West, Larry T.; Rickman, Doug; Luvall, J. C.; Adkins, Wayne

    2004-01-01

    The organic C concentration of surface soil can be used in agricultural fields to vary crop production inputs. Organic C is often highly spatially variable, so that maps of soil organic C can be used to vary crop production inputs using precision farming technology. The objective of this research was to demonstrate the feasibility of mapping soil organic C on three fields, using remotely sensed images of the fields with a bare surface. Enough soil samples covering the range in soil organic C must be taken from each field to develop a satisfactory relationship between soil organic C content and image reflectance values. The number of soil samples analyzed in the three fields varied from 22 to 26. The regression equations differed between fields, but gave highly significant relationships with R2 values of 0.93, 0.95, and 0.89 for the three fields. A comparison of predicted and measured values of soil organic C for an independent set of 2 soil samples taken on one of the fields gave highly satisfactory results, with a comparison equation of % organic C measured + 1.02% organic C predicted, with r2 = 0.87.

  16. Novel hard materials with controlled (W0.5Al0.5)C grain shapes: in-situ high pressure preparation and mechanical properties

    Institute of Scientific and Technical Information of China (English)

    Zhuhui QIAO; Xianfeng MA; Huaguo TANG; Wei ZHAO; Jianwei LIU

    2012-01-01

    A novel hard material with various (W0.5Al0.5)C grain shapes was successfully prepared through mechanical alloying and in-situ high-pressure sintering process.X-ray diffraction apparatus and scanning electron microscopy were used to characterize the phase and the microstructures of the samples.The novel hard materials with “fibrous”,“rounded” and “plate-like” grains,which do not contain sharp edges,have the improved mechanical properties.The bulk boundless (W0.5Al0.5)C hard material with various (W0.5Al0.5)C grain shapes possesses good mechanical properties and light weight.The formation mechanism for the non-equilibrium (W0.5Al0.5)C grains during in-situ high-pressure sintering is also discussed.

  17. Topochemical fluorination of Sr3(M(0.5)Ru(0.5))2O7 (M = Ti, Mn, Fe), n = 2, Ruddlesden-Popper phases.

    Science.gov (United States)

    Romero, Fabio Denis; Bingham, Paul A; Forder, Susan D; Hayward, Michael A

    2013-03-18

    Reaction of the appropriate Sr3(M(0.5)Ru(0.5))2O7 (M = Ti, Mn, Fe), n = 2, Ruddlesden-Popper oxide with CuF2 under flowing oxygen results in formation of the oxide-fluoride phases Sr3(Ti(0.5)Ru(0.5))2O7F2, Sr3(Mn(0.5)Ru(0.5))2O7F2, and Sr3(Fe(0.5)Ru(0.5))2O(5.5)F(3.5) via a topochemical anion insertion/substitution process. Analysis indicates the titanium and manganese phases have Ti(4+), Ru(6+) and Mn(4+), Ru(6+) oxidation state combinations, respectively, while Mössbauer spectra indicate an Fe(3+), Ru(5.5+) combination for the iron phase. Thus, it can be seen that the soft fluorination conditions employed lead to formation of highly oxidized Ru(6+) centers in all three oxide-fluoride phases, while oxidation states of the other transition metal M cations remain unchanged. Fluorination of Sr3(Ti(0.5)Ru(0.5))2O7 to Sr3(Ti(0.5)Ru(0.5))2O7F2 leads to suppression of magnetic order as the fluorinated material approaches metallic behavior. In contrast, fluorination of Sr3(Mn(0.5)Ru(0.5))2O7 and Sr3(Fe(0.5)Ru(0.5))2O7 lifts the magnetic frustration present in the oxide phases, resulting in observation of long-range antiferromagnetic order at low temperature in Sr3(Mn(0.5)Ru(0.5))2O7F2 and Sr3(Fe(0.5)Ru(0.5))2O(5.5)F(3.5). The influence of the topochemical fluorination on the magnetic behavior of the Sr3(M(0.5)Ru(0.5))2O(x)F(y) phases is discussed on the basis of changes to the ruthenium oxidation state and structural distortions.

  18. Inversion of dielectric constant and moisture of bare soil surface from backscattering coefficient

    Institute of Scientific and Technical Information of China (English)

    李宗谦; 冯孔豫

    1997-01-01

    An inverse method of dielectric constant and moisture of bare wet soil surface from backscattering coefficients is presented, which is based upon the small perturbation model of electromagnetic wave scattering from rough surfaces and the empirical and dielectric mixing models of wet soil. Some sets of curves which describe the relation between the moisture of soil and the ratio of like polarization backscattering coefficients σvv and σhh are obtained, and some principles on how to choose the incident frequencies and the incident angles of the electromagnetic wave are given Analysis and calculation show that the mam advantage of this inverse method is its efficiency and simplicity.

  19. Atrazine, triketone herbicides, and their degradation products in sediment, soil and surface water samples in Poland.

    Science.gov (United States)

    Barchanska, Hanna; Sajdak, Marcin; Szczypka, Kornelia; Swientek, Angelika; Tworek, Martyna; Kurek, Magdalena

    2017-01-01

    The aim of this study was to monitor the sediment, soil and surface water contamination with selected popular triketone herbicides (mesotrione (MES) and sulcotrione(SUL)), atrazine (ATR) classified as a possible carcinogen and endocrine disrupting chemical, as well as their degradation products, in Silesia (Poland). Seventeen sediment samples, 24 soil samples, and 64 surface water samples collected in 2014 were studied. After solid-liquid extraction (SLE) and solid phase extraction (SPE), analytes were determined by high-performance liquid chromatography (HPLC) with diode array detection (DAD). Ten years after the withdrawal from the use, ATR was not detected in any of the collected samples; however, its degradation products are still present in 41 % of sediment, 71 % of soil, and 8 % of surface water samples. SUL was determined in 85 % of soil samples; its degradation product (2-chloro-4-(methylosulfonyl) benzoic acid (CMBA)) was present in 43 % of soil samples. In 17 % of sediment samples, CMBA was detected. Triketones were detected occasionally in surface water samples. The chemometric analysis (clustering analysis (CA), single-factor analysis of variance (ANOVA), N-Way ANOVA) was applied to find relations between selected soil and sediment parameters and herbicides concentration. In neither of the studied cases a statistically significant relationship between the concentrations of examined herbicides, their degradation products and soil parameters (organic carbon (OC), pH) was observed.

  20. Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

    Directory of Open Access Journals (Sweden)

    F. Alkhaier

    2012-07-01

    Full Text Available Understanding when and how groundwater affects surface temperature and energy fluxes is significant for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To investigate the shallow groundwater effect under bare soil conditions, we numerically exposed two soil profiles to identical metrological forcing. One of the profiles had shallow groundwater. The different responses that the two profiles manifested were inspected regarding soil moisture, temperature and energy balance at the land surface. The findings showed that the two profiles differed in three aspects: the absorbed and emitted amounts of energy, the portioning out of the available energy and the heat fluency in the soil. We concluded that due to their lower albedo, shallow groundwater areas reflect less shortwave radiation and consequently get a higher magnitude of net radiation. When potential evaporation demand is sufficiently high, a large portion of the energy received by these areas is consumed for evaporation. This increases the latent heat flux and reduces the energy that could have heated the soil. Consequently, lower magnitudes of both sensible and ground heat fluxes are caused to occur. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. For the reliability of remote sensors in detecting shallow groundwater effect, it was concluded that this effect can be sufficiently clear to be detected if at least one of the following conditions occurs: high potential evaporation and high contrast between day and night temperatures. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection.

  1. Fixation of soil surface contamination using natural polysaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Sackschewsky, M.R.

    1993-09-01

    Natural polysaccharides were evaluated as alternatives to commercially available dust-control agents for application in buried-waste and contaminated-soil remediation situations. Materials were identified and evaluated with specific criteria in mind: the materials must be environmentally benign and must not introduce any additional hazardous materials; they must be effective for at least 2 or 3 days, but they do not necessarily have to be effective for more than 2 to 3 weeks; they should be relatively resistant to light traffic; they must not interfere with subsequent soil treatment techniques, especially soil washing; and they must be relatively inexpensive. Two products, a pregelled potato starch and a mixture of carbohydrates derived from sugar beets, were selected for evaluation. Testing included small- and large-scale field demonstrations, laboratory physical property analyses, and wind-tunnel evaluations.

  2. Ferromagnetic half-metallic characteristic in bulk Ni 0.5M 0.5O (M=Cu, Zn and Cd): A GGAU study

    KAUST Repository

    Mi, Wenbo

    2012-07-01

    Ferromagnetic half metallicity with a high spin polarization of 100% was predicted in the bulk Ni 0.5Cu 0.5O using density-functional theory method. The band gap of majority spin is 3.45 eV for Ni 0.5Cu 0.5O. The density of states of minority spin at the Fermi level are mainly from Cu 3d and O 2p in the Ni 0.5Cu 0.5O. The magnetic moments are from Ni 3d states. Ni 0.5Zn 0.5O and Ni 0.5Cd 0.5O systems are ferromagnetic insulators, but the magnetic moment of Ni 2 ions is enhanced by the Zn and Cd incorporation. Therefore, Ni 0.5Cu 0.5O is the potential candidate for spintronics devices because of the predicted high spin polarization. © 2012 Elsevier Ltd. All rights reserved.

  3. Structure and photoluminescence properties of Ce0.5Zr0.5O2:Eu3+ nanoparticles synthesized by hydrothermal method

    Science.gov (United States)

    Ozawa, Masakuni; Yoshimura, Yusuke; Kobayashi, Katsutoshi

    2017-01-01

    Eu3+-doped Ce0.5Zr0.5O2 nanocrystals were prepared by a hydrothermal method. The structural and optical properties of the samples were characterized by X-ray diffraction, Raman scattering and photoluminescence spectra. No luminescence was observed for Ce0.5Zr0.5O2, while Ce0.5Zr0.5O2:Eu3+ nanoparticles as-prepared and calcined at 400 °C showed emission due to Eu3+. The emission spectrum of the Eu3+ site shows that the total intensity decreases with increasing concentration of Eu3+ from 1 to 10% in Ce0.5Zr0.5O2. The broad band in the excitation spectrum of calcined Ce0.5Zr0.5O2:Eu3+ originates from the charge transfer (CT) transition. The local distortion and the asymmetry factor around the Eu3+ centers were discussed with the Raman and photoluminescence spectra. The present study provides both knowledge expected to lead to novel nanocrystal phosphor materials and a useful measure for analyzing the catalytic properties of nanocrystalline Ce0.5Zr0.5O2.

  4. Microstructure and magnetic characteristics of nanocrystalline Ni0.5Zn0.5 ferrite synthesized by a spraying-coprecipitation method

    Institute of Scientific and Technical Information of China (English)

    Liu Yin; Qiu Tai

    2007-01-01

    Nanocrystalline Ni0.5Zn0.5 ferrite with average grain sizes ranging from 10 to 100 nm is prepared by using a spraying-coprecipitation method. The results indicate that the nanocrystalline Ni0.5Zn0.5 ferrite is ferromagnetic without the superparamagnetic phenomenon observed at room temperature. Specific saturation magnetization of nanocrystalline Ni0.5Zn0.5 ferrite increases from 40.2 to 75.6 emu/g as grain size increases from 11 to 94nm. Coercivity of nanocrystalline Ni0.5Zn0.5 ferrite increases monotonically when d < 62 nm. The relationship between the coercivity and the mean grain size is well fitted into a relation Hc ~ d3. A theoretically evaluated value of the critical grain size is 141nm larger than the experimental value 62nm for nanocrystalline Ni0.5Zn0.5 ferrite. The magnetic behaviour of nanocrystalline Ni0.5Zn0.5 ferrite may be explained by using the random anisotropy theory.

  5. Parasitic contamination of surface and deep soil in different areas of Sari in north of Iran

    Institute of Scientific and Technical Information of China (English)

    Hajar Ziaei Hezarjaribi; Ahmad Daryani; Nastaran Amani Kelarijani; Mina Eskandari Shahraki; Beheshteh Haghparast Kenari; Mohammad Saaid Dayer; Najla Hamidianfar; Fatemeh Ghaffarifar

    2016-01-01

    Objective:To study the parasitic contamination of soil in selected areas of Sari, north of Iran. Methods: A cross-sectional study was conducted to identify all available parasites in surface and deep soil. In this study 580 soil samples (278 deep soil and 302 topsoil samples) from 21 different locations were collected from pathways, parks, greenhouses, estates around the city, cemetery, main squares, farmlands, fenced gardens and seashores. Depending on the soil type, two samples were prepared, from surface and deep soil at the depth of 3 to 5 cm. After performing various stages of preparation, including cleaning and washing, smoothing and flotation, parasitic elements were examined microscopically and quantitative parasite counting was done using a McMaster slide. Results:The results showed that the highest rate of parasitic contamination was related to nematodes larvae (26.11%). Other contaminants such asEntamoeba andAcanthamoeba cysts, vacuolizationBlastocystis hominis form, oocyte containing sporocysts,Toxascaris eggs, nematoda larvae,Hymenolepis eggs,Ascaris eggs,Fasciola eggs, hookworm eggs,Toxocara eggs, insects' larvae and other ciliated and flagellated organisms were also observed. The results of this study showed that the highest contamination was found in public garden (25.80%) both in surface (29.30%) and in deep soil (21.12%), while the lowest level of contamination was observed in seashore surface soil (4.90%). Conclusions:The results showed that soil can provide a potential medium for the spread of soil transmitted parasitic diseases in the environment; therefore, preventive programs are needed.

  6. Characterization of MASDs of surface soils in north China and its influence on estimating dust emission

    Institute of Scientific and Technical Information of China (English)

    MEI Fanmin; ZHANG Xiaoye; LU Huayu; SHEN Zhenxing; WANG Yaqiang

    2004-01-01

    The micro-aggregated size distribution (MASD) of surface soil is an important parameter for modelling dust emission. However,there is no dataset of MASDs of all surface soil types in north China.The MASDs are here presented,measured by dry sieving,for typical surface soil samples,including sandy soil,gravelly sand soil,gravelly loam soil,loam soil and silt loam soil,collected from sandy deserts,Gobi deserts,oases,farmlands in steppe regions and steppe areas in north China.The MASDs of various surface soil types exhibit a combination of several log-normal distributions of five separated sizes with mean mass median diameters (MMDs) of 90,210,390,600 and 980 цm,respectively,and mean standard deviations (SDs) of 1.25,1.40,1.25,1.35 and 1.25 respectively. The log-normal distributions correspond to very fine sand,fine sand,medium sand,coarse sand and very coarse sand population.On the basis of characterization of the retrieved MASDs of various surface soil types in north China,dust emission fluxes are modelled by a dust production model (DPM model).It is shown that dust emission has been significantly influenced by MASDs.Fine sand and very fine sand are always associated with the highest dust emission fluxes. Emission fluxes of the medium sand, gravelly sand soil,gravelly loam soil and loam soil are lower than those of very fine sand and fine sand,but larger than those of the coarse sand.The differences in dust emission fluxes vary among the different soil types from 101 to 103 цg·m-2·s-1.Dust emission fluxes from sandy deserts and farmlands covered with sand sheets in north China rang from 101 to 104 цg·m-2·s-1 while those from Gobi deserts,farmlands and steppes with gravelly desertification range from 101 to 102 цg·m-2· s-1.The modelled results indicate that deserts and farmlands with sand are the major dust sources in north China.

  7. Polyethylene imine-grafted ACF@BiOI0.5Cl0.5 as a recyclable photocatalyst for high-efficient dye removal by adsorption-combined degradation

    Science.gov (United States)

    Li, Hongyan; Li, Najun; Chen, Dongyun; Xu, Qingfeng; Lu, Jianmei

    2017-05-01

    A recyclable photocatalyst with adsorption property was prepared for high-efficient complete removal of anionic dyes from water by synergetic adsorption and photocatalytic degradation. Firstly, binary bismuth oxyhalide composed as BiOI0.5Cl0.5 was immobilized on activated carbon fibers (ACF) to get a recyclable photocatalyst (ACF@BiOI0.5Cl0.5) via one-step solvothermal method. Then it was modified with branched polyethylene imine (PEI) whose abundant amino groups can adsorb contaminants from water by electrostatic interaction. SEM images showed that the nanosheets-based flower-like photocatalytic microspheres uniformly distributed on the ACF surface after grafting of small amount of PEI. But from TGA results we can deduce that the percentage of PEI grafted onto ACF@BiOI0.5Cl0.5 is about 18 wt%. During the synergistic process, the grafted PEI and immobilized BiOI0.5Cl0.5 are worked as the adsorbent and the photocatalyst, respectively. In addition, ACF, as flexible, conductive and corrosion-resistant supports, are beneficial to the photocatalytic degradation process. So the obtained composite PEI-g-ACF@BiOI0.5Cl0.5 has a high removal efficiency of contaminants under visible light irradiation with the synergistic effect of adsorption and photocatalytic degradation. And after facial separation without centrifuge, it can be reused without regeneration because of the real-time complete degradation of the adsorbed contaminants on the surface of the composite photocatalyst.

  8. Variability of soil enzyme activities and vegetation succession following boreal forest surface soil transfer to an artificial hill

    Directory of Open Access Journals (Sweden)

    Maarit Niemi

    2014-08-01

    Full Text Available A landfill site in southern Finland was converted into urban green space by covering it with a layer of fresh forest humus transferred from nearby construction sites. The aim was to develop the 70 m high artificial hill into a recreational area with high biodiversity of flora and fauna. Forest humus was used as a source of organic matter, plant roots, seeds, soil fauna and microorganisms in order to enable rapid regeneration of diverse vegetation and soil biological functions. In this study we report the results of three years of monitoring of soil enzyme activity and plant species compositional patterns. Monthly soil samples were taken each year between June and September from four sites on the hill and from two standing reference forests using three replicate plots. Activities of 10 different enzymes, soil organic matter (SOM content, moisture, pH and temperature of the surface layer were monitored. Abundances of vascular plant species were surveyed on the same four hill sites between late May and early September, three times a season in 2004 and 2005. Although the addition of organic soil considerably increased soil enzyme activities (per dw, the activities at the covered hill sites were far lower than in the reference forests. Temporal changes and differences between sites were analysed in more detail per soil organic matter (SOM in order to reveal differences in the quality of SOM. All the sites had a characteristic enzyme activity pattern and two hill sites showed clear temporal changes. The enzyme activities in uncovered topsoil increased, whereas the activities at the covered Middle site decreased, when compared with other sites at the same time. The different trend between Middle and North sites in enzyme activities may reflect differences in humus material transferred to these sites, but difference in the succession of vegetation affects enzyme activities strongly. Middle yielded higher β-sitosterol content in 2004, as an indication

  9. Rainfall intensity and phosphorus source effects on phosphorus transport in surface runoff from soil trays.

    Science.gov (United States)

    Shigaki, Francirose; Sharpley, Andrew; Prochnow, Luis Ignacio

    2007-02-01

    Phosphorus runoff from agricultural fields amended with mineral fertilizers and manures has been linked to freshwater eutrophication. A rainfall simulation study was conducted to evaluate the effects of different rainfall intensities and P sources differing in water soluble P (WSP) concentration on P transport in runoff from soil trays packed with a Berks loam and grassed with annual ryegrass (Lolium multiflorum Lam.). Triple superphosphate (TSP; 79% WSP), low-grade super single phosphate (LGSSP; 50% WSP), North Carolina rock phosphate (NCRP; 0.5% WSP) and swine manure (SM; 70% WSP), were broadcast (100 kg total P ha-1) and rainfall applied at 25, 50 and 75 mm h-1 1, 7, 21, and 56 days after P source application. The concentration of dissolved reactive (DRP), particulate (PP), and total P (TP) was significantly (Prunoff with a rainfall intensity of 75 than 25 mm h-1 for all P sources. Further, runoff DRP increased as P source WSP increased, with runoff from a 50 mm h-1 rain 1 day after source application having a DRP concentration of 0.25 mg L-1 for NCRP and 28.21 mg L-1 for TSP. In contrast, the proportion of runoff TP as PP was greater with low (39% PP for NCRP) than high WSP sources (4% PP for TSP) averaged for all rainfall intensities. The increased PP transport is attributed to the detachment and transport of undissolved P source particles during runoff. These results show that P source water solubility and rainfall intensity can influence P transport in runoff, which is important in evaluating the long-term risks of P source application on P transport in surface runoff.

  10. Rapid soil development after windthrow disturbance in pristine forests.

    Science.gov (United States)

    B.T. Bormann; H. Spaltenstein; M.H. McClellan; F.C. Ugolini; K. Cromack; S.M. Nay

    1995-01-01

    1. We examined how rapidly soils can change during secondary succession by observing soil development on 350-year chronosequences in three pristine forest ecosystems in south-east Alaska. 2. Soil surfaces, created by different windthrow events of known or estimated age, were examined within each of three forest stands (0.5-2.0 ha plots; i.e. a within-stand...

  11. Multi-Temporal Evaluation of Soil Moisture and Land Surface Temperature Dynamics Using in Situ and Satellite Observations

    Directory of Open Access Journals (Sweden)

    Miriam Pablos

    2016-07-01

    Full Text Available Soil moisture (SM is an important component of the Earth’s surface water balance and by extension the energy balance, regulating the land surface temperature (LST and evapotranspiration (ET. Nowadays, there are two missions dedicated to monitoring the Earth’s surface SM using L-band radiometers: ESA’s Soil Moisture and Ocean Salinity (SMOS and NASA’s Soil Moisture Active Passive (SMAP. LST is remotely sensed using thermal infrared (TIR sensors on-board satellites, such as NASA’s Terra/Aqua MODIS or ESA & EUMETSAT’s MSG SEVIRI. This study provides an assessment of SM and LST dynamics at daily and seasonal scales, using 4 years (2011–2014 of in situ and satellite observations over the central part of the river Duero basin in Spain. Specifically, the agreement of instantaneous SM with a variety of LST-derived parameters is analyzed to better understand the fundamental link of the SM–LST relationship through ET and thermal inertia. Ground-based SM and LST measurements from the REMEDHUS network are compared to SMOS SM and MODIS LST spaceborne observations. ET is obtained from the HidroMORE regional hydrological model. At the daily scale, a strong anticorrelation is observed between in situ SM and maximum LST (R ≈ − 0.6 to −0.8, and between SMOS SM and MODIS LST Terra/Aqua day (R ≈ − 0.7. At the seasonal scale, results show a stronger anticorrelation in autumn, spring and summer (in situ R ≈ − 0.5 to −0.7; satellite R ≈ − 0.4 to −0.7 indicating SM–LST coupling, than in winter (in situ R ≈ +0.3; satellite R ≈ − 0.3 indicating SM–LST decoupling. These different behaviors evidence changes from water-limited to energy-limited moisture flux across seasons, which are confirmed by the observed ET evolution. In water-limited periods, SM is extracted from the soil through ET until critical SM is reached. A method to estimate the soil critical SM is proposed. For REMEDHUS, the critical SM is estimated to be ∼0

  12. Revegetation of Acid Rock Drainage (ARD) Producing Slope Surface Using Phosphate Microencapsulation and Artificial Soil

    Science.gov (United States)

    Kim, Jae Gon

    2017-04-01

    Oxidation of sulfides produces acid rock drainage (ARD) upon their exposure to oxidation environment by construction and mining activities. The ARD causes the acidification and metal contamination of soil, surface water and groundwater, the damage of plant, the deterioration of landscape and the reduction of slope stability. The revegetation of slope surface is one of commonly adopted strategies to reduce erosion and to increase slope stability. However, the revegetation of the ARD producing slope surface is frequently failed due to its high acidity and toxic metal content. We developed a revegetation method consisting of microencapsualtion and artificial soil in the laboratory. The revegetation method was applied on the ARD producing slope on which the revegetation using soil coverage and seeding was failed and monitored the plant growth for one year. The phosphate solution was applied on sulfide containing rock to form stable Fe-phosphate mineral on the surface of sulfide, which worked as a physical barrier to prevent contacting oxidants such as oxygen and Fe3+ ion to the sulfide surface. After the microencapsulation, two artificial soil layers were constructed. The first layer containing organic matter, dolomite powder and soil was constructed at 2 cm thickness to neutralize the rising acidic capillary water from the subsurface and to remove the dissolved oxygen from the percolating rain water. Finally, the second layer containing seeds, organic matter, nutrients and soil was constructed at 3 cm thickness on the top. After application of the method, the pH of the soil below the artificial soil layer increased and the ARD production from the rock fragments reduced. The plant growth showed an ordinary state while the plant died two month after germination for the previous revegetation trial. No soil erosion occurred from the slope during the one year field test.

  13. Variation of clonal, mesquite-associated rhizobial and bradyrhizobial populations from surface and deep soils by symbiotic gene region restriction fragment length polymorphism and plasmid profile analysis.

    Science.gov (United States)

    Thomas, P M; Golly, K F; Zyskind, J W; Virginia, R A

    1994-04-01

    Genetic characteristics of 14 Rhizobium and 9 Bradyrhizobium mesquite (Prosopis glandulosa)-nodulating strains isolated from surface (0- to 0.5-m) and deep (4- to 6-m) rooting zones were determined in order to examine the hypothesis that surface- and deep-soil symbiont populations were related but had become genetically distinct during adaptation to contrasting soil conditions. To examine genetic diversity, Southern blots of PstI-digested genomic DNA were sequentially hybridized with the nodDABC region of Rhizobium meliloti, the Klebsiella pneumoniae nifHDK region encoding nitrogenase structural genes, and the chromosome-localized ndvB region of R. meliloti. Plasmid profile and host plant nodulation assays were also made. Isolates from mesquite nodulated beans and cowpeas but not alfalfa, clover, or soybeans. Mesquite was nodulated by diverse species of symbionts (R. meliloti, Rhizobium leguminosarum bv. phaseoli, and Parasponia bradyrhizobia). There were no differences within the groups of mesquite-associated rhizobia or bradyrhizobia in cross-inoculation response. The ndvB hybridization results showed the greatest genetic diversity among rhizobial strains. The pattern of ndvB-hybridizing fragments suggested that surface and deep strains were clonally related, but groups of related strains from each soil depth could be distinguished. Less variation was found with nifHDK and nodDABC probes. Large plasmids (>1,500 kb) were observed in all rhizobia and some bradyrhizobia. Profiles of plasmids of less than 1,000 kb were related to the soil depth and the genus of the symbiont. We suggest that interacting selection pressures for symbiotic competence and free-living survival, coupled with soil conditions that restrict genetic exchange between surface and deep-soil populations, led to the observed patterns of genetic diversity.

  14. Soil surface searching and transport of Euphorbia characias seeds by ants

    Science.gov (United States)

    Espadaler, Xavier; Gómez, Crisanto

    The intensity of exploring the soil surface by ants was studied for the four species involved in the dispersal and predation of seeds of the West-Mediterranean myrmecochorous plant Euphorbia characias. During the dehiscence period (June) the whole soil surface is sccanned in 43 minutes. Not all ants that find a seed take it to the nest. For the four ant species studied ( Pheidole pallidula, Aphaenogaster senilis, Tapinoma nigerrimum, Messor barbarus) the proportion of ants that finally take the seed is 67.6%. In spite of this, the high level of soil surface searching explains the rather short time that seeds remain on the soil before being removed. The presence of an elaiosome is a key element in the outcome of the ant-seed interaction: a seed with elaiosome has a seven-fold increase in probability of being taken to the nest if found by a non-granivorous ant. The predator-avoidance hypothesis for myrmecochory is supported.

  15. Temporal observations of surface soil moisture using a passive microwave sensor

    Science.gov (United States)

    Jackson, T. J.; O'Neill, P.

    1987-01-01

    A series of 10 aircraft flights was conducted over agricultural fields to evaluate relationships between observed surface soil moisture and soil moisture predicted using passive microwave sensor observations. An a priori approach was used to predict values of surface soil moisture for three types of fields: tilled corn, no-till corn with soybean stubble, and idle fields with corn stubble. Acceptable predictions were obtained for the tilled corn fields, while poor results were obtained for the others. The source of error is suspected to be the density and orientation of the surface stubble layer; however, further research is needed to verify this explanation. Temporal comparisons between observed, microwave predicted, and soil water-simulated moisture values showed similar patterns for tilled well-drained fields. Divergences between the observed and simulated measurements were apparent on poorly drained fields. This result may be of value in locating and mapping hydrologic contributing areas.

  16. Dynamic visco-plastic memorial nested yield surface model of soil

    Institute of Scientific and Technical Information of China (English)

    Haiyang ZHUANG; Guoxing CHEN; Dinghua ZHU

    2008-01-01

    Under cyclic loadings, the plastic strain of soft soil will take place under very small shear strain. So the viscoplastic model is appropriate to be used to model the dynamic characteristics of soft soil. Based on the principles of geotechnical plastic mechanics, the incremental visco-plastic memorial nested yield surface model is developed by using the field theory of nonlinear isotropic materials and the theory of kinematical hardening modulus. At the end of anyone time increment, the inverted loading surface, the damaged surface and the initial loading surface which is tangent with the inside of inverted loading surface are memorized respectively. The kinematical behavior of yield surface is defined by using these three surfaces. The developed model in this paper is successfully implemented in ABAQUS using FORTRAN subroutine. The predicted stress-strain relationships of soft soil are compared with the test results given by dynamic triaxial tests. It is proved that the cyclic undrained stress-strain relation of soils can be fairly simulated by the model. At last, the nonlinear earthquake response of a representative soft site in Nanjing city is calculated with the dynamic behavior of soils modeled by the new developed model. The results are accordant to the earthquake response of soft site given by other scholars.

  17. Modeling spatial and seasonal soil moisture in a semi arid hillslope: The impact of integrating soil surface seal parameters

    Science.gov (United States)

    Sela, Shai; Svoray, Tal; Assouline, Shmuel

    2010-05-01

    Modeling hillslope hydrology and the complex and coupled reaction of runoff processes to rainfall, lies in the focus of a growing number of research studies. The ability to characterize and understand the mechanisms underlying the complex hillslope soil moisture patterns, which trigger spatially variable non linear runoff initiation, still remains a current hydrological challenge especially in ungauged catchments. In humid climates, connectivity of transient moisture patches was suggested as a unifying concept for studying thresholds for subsurface flow and redistribution of soil moisture at the hillslope scale. In semiarid areas, however, transient moisture patches control also the differentiation between evaporation and surface runoff and the ability to identify a unifying concept controlling the large variability of soil moisture at the hillslope scale remains an open research gap. At the LTER Lehavim site in the center of Israel (31020' N, 34045' E) a typical hillslope (0.115 km2) was chosen offering different aspects and a classic geomorphologic banding. The annual rainfall is 290 mm, the soils are brown lithosols and arid brown loess and the dominant rock formations are Eocenean limestone and chalk with patches of calcrete. The vegetation is characterised by scattered dwarf shrubs (dominant species Sarcopoterium spinosum) and patches of herbaceous vegetation, mostly annuals, are spread between rocks and dwarf shrubs. An extensive spatial database of soil hydraulic and environmental parameters (e.g. slope, radiation, bulk density) was measured in the field and interpolated to continuous maps using geostatistical techniques and physically based modelling. To explore the effect of soil surface sealing, Mualem and Assouline (1989) equations describing the change in hydraulic parameters resulting from soil seal formation were applied. Two simple indices were developed to describe local evaporation values and contribution of water from rock outcrops to the soil

  18. Mesoporous Ti(0.5)Cr(0.5)N supported PdAg nanoalloy as highly active and stable catalysts for the electro-oxidation of formic acid and methanol.

    Science.gov (United States)

    Cui, Zhiming; Yang, Minghui; DiSalvo, Francis J

    2014-06-24

    We report a robust noncarbon Ti0.5Cr0.5N support synthesized by an efficient solid-solid phase separation method. This ternary nitride exhibits highly porous, sintered, and random network structure with a crystallite size of 20-40 nm, resulting in a high specific surface area. It is not only kinetically stable in both acid and alkaline media, but also electrochemically stable in the potential range of fuel cell operation. Two typical anode reactions, formic acid oxidation in acid media and methanol oxidation in alkaline media, are employed to investigate the possibility of Ti0.5Cr0.5N as an alternative to carbon. Bimetallic PdAg nanoparticles (∼4 nm) act as anode catalysts for the two anode reactions. PdAg/Ti0.5Cr0.5N exhibits much higher mass activity and durability for the two reactions than PdAg/C and Pd/C catalyst, suggesting that mesoporous Ti0.5Cr0.5N is a very promising support in both acid and alkaline media.

  19. Structural, thermal, laser damage, photoconductivity, NLO and mechanical properties of modified vertical Bridgman method grown AgGa0.5In0.5Se2 single crystal

    Science.gov (United States)

    Vijayakumar, P.; Ramasamy, P.

    2016-08-01

    AgGa0.5In0.5Se2 single crystal was grown using modified vertical Bridgman method. The structural perfection of the AgGa0.5In0.5Se2 single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. The structural and compositional uniformities of AgGa0.5In0.5Se2 were studied using Raman scattering spectroscopy at room temperature. The FWHM of the Γ1 (W1) and Γ5L (Γ15) measured at different regions of the crystal confirms that the composition throughout its length is fairly uniform. Thermal properties of the as-grown crystal, including specific heat, thermal diffusivity and thermal conductivity have been investigated. The multiple shot surface laser damage threshold value was measured using Nd:YAG laser. Photoconductivity measurements with different temperatures have confirmed the positive photoconducting behavior. Second harmonic generation (SHG) on powder samples has been measured using the Kurtz and Perry technique and the results display that AgGa0.5In0.5Se2 is a phase-matchable NLO material. The hardness behavior has been measured using Vickers micro hardness measurement and the indentation size effect has been observed. The classical Meyer's law, propositional resistance model and modified propositional resistance model have been used to analyse the micro hardness behavior.

  20. One-dimensional SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers and enhancement magnetic property.

    Science.gov (United States)

    Song, Fuzhan; Shen, Xiangqian; Liu, Mingquan; Xiang, Jun

    2011-08-01

    SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers of diameters about 100 nm with mass ratio 1:1 have been prepared by the electrospinning and calcination process. The SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrites are formed after calcined at 700 degrees C for 2 hours. The composite ferrite nanofibers are fabricated from nanosized Ni(0.5)Zn(0.5)Fe2O4 and SrFe12O19 ferrite grains with a uniform phase distribution. The ferrite grain size increases from about 11 to 36 nm for Ni(0.5)Zn(0.5)Fe12O4 and 24 to 56 nm for SrFe12O19 with the calcination temperature increasing from 700 to 1100 degrees C. With the ferrite grain size increasing, the coercivity (Hc) and remanence (Mr) for the SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers initially increase, reaching a maximum value of 118.4 kA/m and 31.5 Am2/kg at the grain size about 40 nm (SrFe12O19) and 24 nm (Ni(0.5)Zn(0.5)Fe2O4) respectively, and then show a reduction tendency with a further increase of the ferrite grain size. The specific saturation magnetization (Msh) of 63.2 Am2/kg for the SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers obtained at 900 degrees C for 2 hours locates between that for the single SrFe12O19 ferrite (48.5 Am2/kg) and the single Ni(0.5)Zn(0.5)Fe2O4 ferrite (69.3 Am2/kg). In particular, the Mr value 31.5 Am2/kg for the SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers is much higher than that for the individual SrFe12O19 (25.9 Am2/kg) and Ni(0.5)Zn(0.5)Fe2O4 ferrite (11.2 Am2/kg). These enhanced magnetic properties for the composite ferrite nanofibers can be attributed to the exchange-coupling interaction in the composite.

  1. Estimating surface turbulent heat fluxes from land surface temperature and soil moisture observations using the particle batch smoother

    Science.gov (United States)

    Lu, Yang; Dong, Jianzhi; Steele-Dunne, Susan C.; van de Giesen, Nick

    2016-11-01

    Surface heat fluxes interact with the overlying atmosphere and play a crucial role in meteorology, hydrology, and climate change studies, but in situ observations are costly and difficult. It has been demonstrated that surface heat fluxes can be estimated from assimilation of land surface temperature (LST). One approach is to estimate a neutral bulk heat transfer coefficient (CHN) to scale the sum of turbulent heat fluxes, and an evaporative fraction (EF) that represents the partitioning between fluxes. Here the newly developed particle batch smoother (PBS) is implemented. The PBS makes no assumptions about the prior distributions and is therefore well-suited for non-Gaussian processes. It is also particularly advantageous for parameter estimation by tracking the entire prior distribution of parameters using Monte Carlo sampling. To improve the flux estimation on wet or densely vegetated surfaces, a simple soil moisture scheme is introduced to further constrain EF, and soil moisture observations are assimilated simultaneously. This methodology is implemented with the FIFE 1987 and 1988 data sets. Validation against observed fluxes indicates that assimilating LST using the PBS significantly improves the flux estimates at both daily and half-hourly timescales. When soil moisture is assimilated, the estimated EFs become more accurate, particularly when the surface heat flux partitioning is energy-limited. The feasibility of extending the methodology to use remote sensing observations is tested by limiting the number of LST observations. Results show that flux estimates are greatly improved after assimilating soil moisture, particularly when LST observations are sparse.

  2. Cross-satellite comparison of operational land surface temperature products derived from MODIS and ASTER data over bare soil surfaces

    Science.gov (United States)

    Duan, Si-Bo; Li, Zhao-Liang; Cheng, Jie; Leng, Pei

    2017-04-01

    The collection 6 (C6) MODIS land surface temperature (LST) product is publicly available for the user community. Compared to the collection 5 (C5) MODIS LST product, the C6 MODIS LST product has been refined over bare soil pixels. Assessing the accuracy of the C6 MODIS LST product will help to facilitate the use of the LST product in various applications. In this study, we present a cross-satellite comparison to evaluate the accuracy of the C6 MODIS LST product (MOD11_L2) over bare soil surfaces under various atmospheric and surface conditions using the ASTER LST product as a reference. For comparison, the C5 MODIS LST product was also used in the analysis. The absolute biases (0.2-1.5 K) of the differences between the C6 MODIS LST and ASTER LST over bare soil surfaces are approximately two times less than those (0.6-3.8 K) of the differences between the C5 MODIS LST and ASTER LST. Furthermore, the RMSEs (0.7-2.3 K) over bare soil surfaces for the C6 MODIS LST are significantly smaller than those (0.9-4.2 K) for the C5 MODIS LST. These results indicate that the accuracy of the C6 MODIS LST product is much better than that of the C5 MODIS LST product. We recommend that the user community employs the C6 MODIS LST product in their applications.

  3. Polycyclic aromatic hydrocarbons in urban street dust and surface soil: comparisons of concentration, profile, and source.

    Science.gov (United States)

    Wang, De-Gao; Yang, Meng; Jia, Hong-Liang; Zhou, Lei; Li, Yi-Fan

    2009-02-01

    Street dust and surface soil samples in urban areas of Dalian, a coastal city in Liaoning Province, China, were collected and analyzed for 25 polycyclic aromatic hydrocarbons (PAHs). The concentrations, distribution, and sources of PAHs in dust and soil were determined. The concentrations of total PAHs in street dust ranged between 1890 and 17,070 ng/g (dry weight), with an average of 7460 ng/g, whereas the concentrations of total PAHs in surface soil varied greatly, from 650 to 28,900 ng/g, with a mean value of 6440 ng/g. Statistical paired t-test confirmed that total PAH concentrations have no significant difference between street dust and surface soil. Mean PAH concentrations in two type samples were much higher at industrial sites than at business/residential or garden sites. PAHs were dominated by higher molecular weight PAH (4- to 6-ring) homologues, which accounted for about 73% and 72% of total PAHs in street dust and surface soil, respectively. Principal component analysis was used in source apportionment of PAHs in dust and soil. Pyrogenic and petrogenic sources contributed 70% and 22.4% of total PAHs in street dusts, and fossil fuel (coal and petroleum) and biomass combustion accounted for 64.4% and 5.6% of total PAHs in pyrogenic sources, respectively. In surface soil, total PAHs were dominated by pyrogenic sources. The diagnostic ratios of benz[a]anthracene/chrysene confirmed that PAHs in street dust and surface soil of a Dalian urban zone might come mostly from the emission of local sources.

  4. Plant and soil modifications by continuous surface effluent application

    Energy Technology Data Exchange (ETDEWEB)

    Tedesco, M.J.; Levien, R. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Dept. of Solos; Mohrdieck, F.G.; Rodrigues, N.R. [CORSAN-SITEL, Triunfo, RS (Brazil). Polo Petroquimico do Sul. Dept. de Operacao e Manutencao; Flores, A.I.P.

    1993-12-31

    In order to study the effects on soil and plants of the liquid effluent generated by a the Integrated Liquid Effluent Treatment System of a large Brazilian petrochemical complex, a field study was conducted in four areas which received the effluent and compared to control sites. This work presents some results of this study. 12 refs., 1 fig., 3 tabs.

  5. Variations in FASST Predictions of Soil Surface Temperatures

    Science.gov (United States)

    2006-04-01

    technical reviews of the manuscript. Rachel Jordan’s comments on Appendix B improved its usefulness to modelers of soil state. Margo Burgess of the...Crushed stone 1.82 0–8 0.51 A-13 Crushed shale and limestone screenings 1.76 0–8 A-16 Red-brown fine silty sand with fine to medium gravel

  6. Analysis of surface soil moisture patterns in agricultural landscapes using Empirical Orthogonal Functions

    Directory of Open Access Journals (Sweden)

    W. Korres

    2010-05-01

    Full Text Available Soil moisture is one of the fundamental variables in hydrology, meteorology and agriculture. Nevertheless, its spatio-temporal patterns in agriculturally used landscapes that are affected by multiple natural (rainfall, soil, topography etc. and agronomic (fertilisation, soil management etc. factors are often not well known. The aim of this study is to determine the dominant factors governing the spatio-temporal patterns of surface soil moisture in a grassland and an arable test site that are located within the Rur catchment in Western Germany. Surface soil moisture (0–6 cm was measured in an approx. 50×50 m grid during 14 and 17 measurement campaigns (May 2007 to November 2008 in both test sites. To analyse the spatio-temporal patterns of surface soil moisture, an Empirical Orthogonal Function (EOF analysis was applied and the results were correlated with parameters derived from topography, soil, vegetation and land management to link the patterns to related factors and processes. For the grassland test site, the analysis resulted in one significant spatial structure (first EOF, which explained 57.5% of the spatial variability connected to soil properties and topography. The statistical weight of the first spatial EOF is stronger on wet days. The highest temporal variability can be found in locations with a high percentage of soil organic carbon (SOC. For the arable test site, the analysis resulted in two significant spatial structures, the first EOF, which explained 38.4% of the spatial variability, and showed a highly significant correlation to soil properties, namely soil texture and soil stone content. The second EOF, which explained 28.3% of the spatial variability, is linked to differences in land management. The soil moisture in the arable test site varied more strongly during dry and wet periods at locations with low porosity. The method applied is capable of identifying the dominant parameters controlling spatio-temporal patterns of

  7. Retrieval of Surface and Subsurface Moisture of Bare Soil Using Simulated Annealing

    Science.gov (United States)

    Tabatabaeenejad, A.; Moghaddam, M.

    2009-12-01

    Soil moisture is of fundamental importance to many hydrological and biological processes. Soil moisture information is vital to understanding the cycling of water, energy, and carbon in the Earth system. Knowledge of soil moisture is critical to agencies concerned with weather and climate, runoff potential and flood control, soil erosion, reservoir management, water quality, agricultural productivity, drought monitoring, and human health. The need to monitor the soil moisture on a global scale has motivated missions such as Soil Moisture Active and Passive (SMAP) [1]. Rough surface scattering models and remote sensing retrieval algorithms are essential in study of the soil moisture, because soil can be represented as a rough surface structure. Effects of soil moisture on the backscattered field have been studied since the 1960s, but soil moisture estimation remains a challenging problem and there is still a need for more accurate and more efficient inversion algorithms. It has been shown that the simulated annealing method is a powerful tool for inversion of the model parameters of rough surface structures [2]. The sensitivity of this method to measurement noise has also been investigated assuming a two-layer structure characterized by the layers dielectric constants, layer thickness, and statistical properties of the rough interfaces [2]. However, since the moisture profile varies with depth, it is sometimes necessary to model the rough surface as a layered structure with a rough interface on top and a stratified structure below where each layer is assumed to have a constant volumetric moisture content. In this work, we discretize the soil structure into several layers of constant moisture content to examine the effect of subsurface profile on the backscattering coefficient. We will show that while the moisture profile could vary in deeper layers, these layers do not affect the scattered electromagnetic field significantly. Therefore, we can use just a few layers

  8. Soil Moisture Monitoring using Surface Electrical Resistivity measurements

    Science.gov (United States)

    Calamita, Giuseppe; Perrone, Angela; Brocca, Luca; Straface, Salvatore

    2017-04-01

    The relevant role played by the soil moisture (SM) for global and local natural processes results in an explicit interest for its spatial and temporal estimation in the vadose zone coming from different scientific areas - i.e. eco-hydrology, hydrogeology, atmospheric research, soil and plant sciences, etc... A deeper understanding of natural processes requires the collection of data on a higher number of points at increasingly higher spatial scales in order to validate hydrological numerical simulations. In order to take the best advantage of the Electrical Resistivity (ER) data with their non-invasive and cost-effective properties, sequential Gaussian geostatistical simulations (sGs) can be applied to monitor the SM distribution into the soil by means of a few SM measurements and a densely regular ER grid of monitoring. With this aim, co-located SM measurements using mobile TDR probes (MiniTrase), and ER measurements, obtained by using a four-electrode device coupled with a geo-resistivimeter (Syscal Junior), were collected during two surveys carried out on a 200 × 60 m2 area. Two time surveys were carried out during which Data were collected at a depth of around 20 cm for more than 800 points adopting a regular grid sampling scheme with steps (5 m) varying according to logistic and soil compaction constrains. The results of this study are robust due to the high number of measurements available for either variables which strengthen the confidence in the covariance function estimated. Moreover, the findings obtained using sGs show that it is possible to estimate soil moisture variations in the pedological zone by means of time-lapse electrical resistivity and a few SM measurements.

  9. Valence behavior of Eu-ions in intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5}

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Abhishek, E-mail: apandey@ameslab.gov [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Mazumdar, Chandan, E-mail: chandan.mazumdar@saha.ac.in [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Ranganathan, R. [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Raghavendra Reddy, V.; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandawa Road, Indore (India)

    2011-12-15

    We have studied the valence behavior of rare-earth ions, in particular Eu-ions, in a cubic intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} which is a homogeneous solid solution of two mixed-valent compounds CePd{sub 3} and EuPd{sub 3}B. Results of {sup 151}Eu Moessbauer spectroscopic measurements show that two different valence states, i.e., divalent- and trivalent-like states of Eu-ions exist in the compound. The possible reason for the observed heterogeneous valency vis-a-vis the variation in the chemical environment and the number of nearest-neighbor B atoms surrounding the Eu-ions has been discussed. Our results demonstrate that B incorporation in such Eu-based cubic intermetallic compounds leads to a situation where heterogeneous-valence state of Eu-ions is an energetically favorable ground state. - Highlights: > Intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} crystallizes in a single phase. > Eu-ions in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} are charge-ordered compared to +2.3 valency in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}. > B incorporation makes charge-ordered state of Eu-ions energetically more favorable. > Nearest-neighbor chemical environment affects the Eu valency.

  10. Photodegradation of antibiotics on soil surfaces: laboratory studies on sulfadiazine in an ozone-controlled environment.

    Science.gov (United States)

    Wolters, André; Steffens, Markus

    2005-08-15

    Among the processes affecting transport and degradation of antibiotics released to the environment during application of manure and slurry to agricultural land, photochemical transformations are of particular interest. Drying-out of the top soil layer under field conditions enables sorption of surface-applied antibiotics to soil dust, thus facilitating direct, indirect, and sensitized photodegradation at the soil/atmosphere interface. For studying various photochemical transformation processes of sulfadiazine, a photovolatility chamber designed in accordance with the requirements of the USEPA Guideline and 161-3 was used. Application of 14C-labeled sulfadiazine enabled complete mass balances and allowed for investigating the impact of various surfaces (glass and soil dust) and environmental factors, i.e., irradiation and atmospheric ozone, on photodegradation and volatilization. Volatilization was shown to be a negligible process. Even after increasing the air temperature up to 35 degrees C only minor amounts of sulfadiazine and transformation products (0.01-0.28% of applied radioactivity) volatilized. Due to direct and indirect photodegradation, the highest extent of mineralization to 14CO2 (3.9%), the formation of degradation products and of nonextractable soil residues was measured in irradiated soil dust experiments using ozone concentrations of 200 ppb. However, even in the dark significant mineralization was observed when ozone was present, indicating ozone-controlled transformation of sulfadiazine to occur at the soil surface.

  11. Surface water seal application to minimize volatilization loss of methyl isothiocyanate from soil columns.

    Science.gov (United States)

    Simpson, Catherine R; Nelson, Shad D; Stratmann, Jerry E; Ajwa, Husein A

    2010-06-01

    Metam-sodium (MS, sodium methyldithiocarbamate) has been identified as a promising alternative chemical to replace methyl bromide (MeBr) in soil preplant fumigation. One degradation product of MS in soil is the volatile gas methyl isothiocyanate (MITC) which controls soilborne pests. Inconsistent results associated with MS usage indicate that there is a need to determine cultural practices that increase pest control efficacy. Sealing the soil surface with water after MS application may be a sound method to reduce volatilization loss of MITC from soils and increase the contact time necessary for MITC to control pests. The objective of this research was to develop a preliminary soil surface water application amount that would potentially inhibit the off-gassing rate of MITC. Off-gassing rate was consistently reduced with increasing water seal application. The application of a 2.5-3.8 cm water seal provided significantly lower (71-74% reduction in MITC volatilization) total fumigant loss compared with no water seal. The most favorable reduction in MITC off-gassing was observed in the 2.5 cm water seal. This suggests that volatilization of MITC-generating compounds can be highly suppressed using adequate surface irrigation following chemical application in this soil type (sandy clay loam), based on preliminary bench-scale soil column studies. .

  12. Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

    Directory of Open Access Journals (Sweden)

    F. Alkhaier

    2011-09-01

    Full Text Available Appreciating when and how groundwater affects surface temperature and energy fluxes is important for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To explore the shallow groundwater effect, we numerically exposed two soil profiles – one having shallow groundwater – to the same meteorological forcing, and inspected their different responses regarding surface soil moisture, temperature and energy balance. We found that the two profiles differed in the absorbed and emitted amounts of energy, in portioning out the available energy and in heat fluency within the soil. We conclude that shallow groundwater areas reflect less shortwave radiation due to their lower albedo and therefore they get higher magnitude of net radiation. When potential evaporation demand is high enough, a large portion of the energy received by these areas is spent on evaporation. This makes the latent heat flux predominant, and leaves less energy to heat the soil. Consequently, this induces lower magnitudes of both sensible and ground heat fluxes. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. In view of remote sensors' capability of detecting shallow groundwater effect, we conclude that this effect can be sufficiently clear to be sensed if at least one of two conditions is met: high potential evaporation and big contrast in air temperature between day and night. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection.

  13. Electrostatic versus Electrochemical Doping and Control of Ferromagnetism in Ion-Gel-Gated Ultrathin La0.5Sr0.5CoO3-δ.

    Science.gov (United States)

    Walter, Jeff; Wang, Helin; Luo, Bing; Frisbie, C Daniel; Leighton, Chris

    2016-08-23

    Recently, electrolyte gating techniques employing ionic liquids/gels in electric double layer transistors have proven remarkably effective in tuning charge carrier density in a variety of materials. The ability to control surface carrier densities at levels above 10(14) cm(-2) has led to widespread use in the study of superconductivity, insulator-metal transitions, etc. In many cases, controversy remains over the doping mechanism, however (i.e., electrostatic vs electrochemical (e.g., redox-based)), and the technique has been less applied to magnetic materials. Here, we discuss ion gel gating of nanoscale 8-unit-cell-thick hole-doped La0.5Sr0.5CoO3-δ (LSCO) films, probing in detail the critical bias windows and doping mechanisms. The LSCO films, which are under compressive stress on LaAlO3(001) substrates, are metallic and ferromagnetic (Curie temperature, TC ∼ 170 K), with strong anomalous Hall effect and perpendicular magnetic anisotropy. Transport measurements reveal that negative gate biases lead to reversible hole accumulation (i.e., predominantly electrostatic operation) up to some threshold, whereas positive bias immediately induces irreversibility. Experiments in inert/O2 atmospheres directly implicate oxygen vacancies in this irreversibility, supported by atomic force microscopy and X-ray photoelectron spectroscopy. The results are thus of general importance, suggesting that hole- and electron-doped oxides may respond very differently to electrolyte gating. Reversible voltage control of electronic/magnetic properties is then demonstrated under hole accumulation, including resistivity, magnetoresistance, and TC. The sizable anomalous Hall coefficient and perpendicular anisotropy in LSCO provide a particularly powerful probe of magnetism, enabling direct extraction of the voltage-dependent order parameter and TC shift. The latter amounts to ∼7%, with potential for much stronger modulation at lower Sr doping.

  14. Structural, thermal and electrical conductivity characteristics of Ln0.5Sr0.5Ti0.5Mn0.5O3±d (Ln: La, Nd and Sm) complex perovskites as anode materials for solid oxide fuel cell

    Science.gov (United States)

    Jeong, Jihoon; Azad, Abul K.; Schlegl, Harald; Kim, Byungjun; Baek, Seung-Wook; Kim, Keunsoo; Kang, Hyunil; Kim, Jung Hyun

    2015-03-01

    The Ti and Mn replaced complex perovskites, Ln0.5Sr0.5Ti0.5Mn0.5O3±d (Ln: La, Nd and Sm), were reported as potential anode materials for high temperature-operating solid oxide fuel cells (HT-SOFCs). For the present research study, synthesis, crystallographic, thermal and electrical conductivity properties of Ln0.5Sr0.5Ti0.5Mn0.5O3±d complex perovskites were investigated using X-ray diffraction (XRD), Rietveld method, thermogravimetric analysis (TGA) and electrical conductivity to apply these oxide materials for the HT-SOFC anode materials. XRD results showed that Ln0.5Sr0.5Ti0.5Mn0.5O3±d oxide systems synthesized as single phases did not react with 8 mol% yttria stabilized zirconia (8YSZ) and 10 mol% Gd-doped cerium oxide (CGO91) up to 1500 °C and did not decompose under dry 3.9% hydrogen at 850 °C. The crystal structures of La0.5Sr0.5Ti0.5Mn0.5O3±d (LSTM), Nd0.5Sr0.5Ti0.5Mn0.5O3±d (NSTM) and Sm0.5Sr0.5Ti0.5Mn0.5O3±d (SSTM) showed orthorhombic symmetry with the space group Pbnm and SSTM showed a more distorted structure. Thermogravimetric analysis (TGA) proved weight gains in these three sample occurred under oxidizing conditions and weight loss under reducing conditions. Electrical conductivity values of NSTM were higher than those of LSTM and SSTM under oxidizing and reducing conditions.

  15. Updated global soil map for the Weather Research and Forecasting model and soil moisture initialization for the Noah land surface model

    Science.gov (United States)

    DY, C. Y.; Fung, J. C. H.

    2016-08-01

    A meteorological model requires accurate initial conditions and boundary conditions to obtain realistic numerical weather predictions. The land surface controls the surface heat and moisture exchanges, which can be determined by the physical properties of the soil and soil state variables, subsequently exerting an effect on the boundary layer meteorology. The initial and boundary conditions of soil moisture are currently obtained via National Centers for Environmental Prediction FNL (Final) Operational Global Analysis data, which are collected operationally in 1° by 1° resolutions every 6 h. Another input to the model is the soil map generated by the Food and Agriculture Organization of the United Nations - United Nations Educational, Scientific and Cultural Organization (FAO-UNESCO) soil database, which combines several soil surveys from around the world. Both soil moisture from the FNL analysis data and the default soil map lack accuracy and feature coarse resolutions, particularly for certain areas of China. In this study, we update the global soil map with data from Beijing Normal University in 1 km by 1 km grids and propose an alternative method of soil moisture initialization. Simulations of the Weather Research and Forecasting model show that spinning-up the soil moisture improves near-surface temperature and relative humidity prediction using different types of soil moisture initialization. Explanations of that improvement and improvement of the planetary boundary layer height in performing process analysis are provided.

  16. Potential applications of surface active compounds by Gordonia sp. strain BS29 in soil remediation technologies.

    Science.gov (United States)

    Franzetti, Andrea; Caredda, Paolo; Ruggeri, Claudio; La Colla, Paolo; Tamburini, Elena; Papacchini, Maddalena; Bestetti, Giuseppina

    2009-05-01

    A wide range of structurally different surface active compounds (SACs) is synthesised by many prokaryotic and eukaryotic microorganisms. Due to their properties, microbial SACs have been exploited in environmental remediation techniques. From a diesel-contaminated soil, we isolated the Gordonia sp. strain BS29 which extensively grows on aliphatic hydrocarbons and produces two different types of SACs: extracellular bioemulsans and cell-bound biosurfactants. The aim of this work was to evaluate the potential applications of the strain BS29 and its SACs in the following environmental technologies: bioremediation of soils contaminated by aliphatic and aromatic hydrocarbons, and washing of soils contaminated by crude oil, polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Microcosm bioremediation experiments were carried out with soils contaminated by aliphatic hydrocarbons or PAHs, while batch soil washing experiments were carried out with soils contaminated by crude oil, PAHs or heavy metals. Bioremediation results showed that the BS29 bioemulsans are able to slightly enhance the biodegradation of recalcitrant branched hydrocarbons. On the other hand, we obtained the best results in soil washing of hydrocarbons. The BS29 bioemulsans effectively remove crude oil and PAHs from soil. Particularly, crude oil removal by BS29 bioemulsans is comparable to the rhamnolipid one in the same experimental conditions showing that the BS29 bioemulsans are promising washing agents for remediation of hydrocarbon-contaminated soils.

  17. Efficient photocatalytic removal of nitric oxide with hydrothermal synthesized Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Zhihui, E-mail: jennifer.ai@mail.ccnu.edu.cn; Lu, Gang; Lee, Shuncheng

    2014-11-15

    Highlights: • Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes were prepared via a facile hydrothermal route. • The Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes exhibited superior photocatalytic performances for the removal of nitric oxide. • The Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes show potential for indoor and outdoor air purification. - Abstract: In this study, Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes were synthesized with a facile hydrothermal method using TiO{sub 2} P25 (Degussa) and bismuth citrate (BiC{sub 5}H{sub 6}O{sub 7}) as precursors in concentrated NaOH and ammonia alkali solution. The samples were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The as-prepared Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes exhibited superior activity for photocatalytic removal of gaseous nitric oxide (NO) over TiO{sub 2} P25 (Degussa) under simulated solar-light irradiation, the NO removal rate can reach as high as ca. 200 ppb·min{sup −1} over the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes in a continuous reactor with an initial NO concentration of 400 ppb. The intrinsic hollow-nanotube structure of the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} photocatalysts contributes to its superior activity under simulated solar light. This work provides a facile route to prepare Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes and suggests that the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes are ideal candidates for efficient removal of nitric oxide in indoor/outdoor air.

  18. Improved shape hardening function for bounding surface model for cohesive soils

    Directory of Open Access Journals (Sweden)

    Andrés Nieto-Leal

    2014-08-01

    Full Text Available A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one.

  19. Surface energy balance closure in an arid region: role of soil and heat flux

    NARCIS (Netherlands)

    Heusinkveld, B.G.; Jacobs, A.F.G.; Holtslag, A.A.M.; Berkowicz, S.M.

    2004-01-01

    The large soil heat fluxes in hot desert regions are very important in energy balance studies. Surface energy balance (SEB) observations, however, reveal that there is an imbalance in Surface flux measurements and that it is difficult to isolate those flux measurements causing the imbalance errors.

  20. Improved shape hardening function for bounding surface model for cohesive soils

    Institute of Scientific and Technical Information of China (English)

    Andrés Nieto-Leal; Victor N.Kaliakin

    2014-01-01

    A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one.

  1. Discussion on wind factor influencing the distribution of biological soil crusts on surface of sand dunes

    Institute of Scientific and Technical Information of China (English)

    YongSheng Wu; Hasi Erdun; RuiPing Yin; Xin Zhang; Jie Ren; Jian Wang; XiuMin Tian; ZeKun Li; HengLu Miao

    2013-01-01

    Biological soil crusts are widely distributed in arid and semi-arid regions, whose formation and development have an important impact on the restoration process of the desert ecosystem. In order to explore the relationship between surface airflow and development characteristics of biological soil crusts, we studied surface airflow pattern and development characteristics of biological soil crusts on the fixed dune profile through field observation. Results indicate that the speed of near-surface airflow is the lowest at the foot of windward slope and the highest at the crest, showing an increasing trend from the foot to the crest. At the leeward side, although near-surface airflow increases slightly at the lower part of the slope after an initial sudden decrease at upper part of the slope, its overall trend decreases from the crest. Wind velocity variation coefficient varied at different heights over each observation site. The thickness, shear strength of biological soil crusts and percentage of fine particles at crusts layer decreased from the slope foot to the upper part, showing that biological soil crusts are less developed in high wind speed areas and well developed in low wind speed areas. It can be seen that there is a close relationship between the distribution of biological soil crusts in different parts of the dunes and changes in airflow due to geomorphologic variation.

  2. Spatial Distribution and Pattern Persistence of Surface Soil Moisture and Temperature Over Prairie from Remote Sensing

    Science.gov (United States)

    Chen, Daoyi; Engman, Edwin T.; Brutsaert, Wilfried

    1997-01-01

    Images remotely sensed aboard aircraft during FIFE, namely, PBMR (microwave) soil moisture and NS001 thermal infrared surface temperature, were mapped on the same coordinate system covering the 20 km x 20 km experimental site. For both kinds of image data, the frequency distributions were close to symmetric, and the area average compared reasonably well with the ground based measurements. For any image on any given day, the correlation between the remotely sensed values and collocated ground based measurements over the area was usually high in the case of NS001 surface temperature but low in the case of PBMR soil moisture. On the other hand, at any given flux station the correlation between the PBMR and gravimetric soil moisture over all available days was usually high. The correlation pixel by pixel between images of PBMR on different days was generally high. The preservation of the spatial patterns of soil moisture was also evaluated by considering the correlation station by station between ground-based soil moisture measurements on different days; no persistence of spatial pattern was apparent during wet periods, but a definite pattern gradually established itself toward the end of each drying episode. The spatial patterns of surface temperature revealed by NS001 were not preserved even within a single day. The cross-correlations among the two kinds of images and the vegetation index NDVI were normally poor. This suggests that different processes of vegetation growth, and of the near-surface soil water and energy budgets.

  3. Distribution of 137Cs In the Surface Soil of Serpong Nuclear Site

    Directory of Open Access Journals (Sweden)

    E. Lubis

    2011-08-01

    Full Text Available The distribution of 137Cs in the surface soil layer of Serpong Nuclear Site (SNS was investigated by field sampling. The Objectives of the investigation is finding the profile of 137Cs distribution in the surface soil and the Tf value that can be used for estimation of radiation dose from livestock product-man pathways. The results indicates that the 137Cs activity in surface soil of SNS is 0.80 ± 0,29 Bq/kg, much lower than in the Antarctic. The contribution value of 137Cs from the operation of G.A.Siwabessy Reactor until now is undetectable. The Tf of 137Cs from surface soil to Panisetum Purpureum, Setaria Spha Celata and Imperata Cylindrica grasses were 0.71 ± 0.14, 0.84 ± 0.27 and 0.81 ± 0.11 respectively. The results show that value of the transfer factor of 137Cs varies between cultivated and uncultivated soil and also with the soils with thick humus

  4. NiO-Ce0.5Zr0.5O2 catalysts prepared by citric acid method for steam reforming of ethanol

    Institute of Scientific and Technical Information of China (English)

    YE Jilei; WANG Yang; LIU Yuan

    2008-01-01

    NiO-Ce0.5Zr0.5O2catalysts were prepared by citrate method and used for hydrogen production from steam reforming of ethanol (SRE). The effect of nickel content and space velocity on the catalytic performance was investigated. The prepared catalysts were character-ized with XRD and thermal analysis techniques. 20%NiO-Ce0.5Zr0.5O2 catalyst was very active and selective for hydrogen production via SRE, in which ethanol conversion of 100% could be obtained with feed component of 20% (H2O+EtOH) and 80% N2, water/ethanol of 3/1 in molar ratio at 350 ℃. Also, the catalyst showed good stability for anti-sintering and carbon-resistance. The XRD illuminated that both NiO and Ce0.5Zr0.5O2 crystal sizes were very small in NiO-Ce0.5Zr0.5O2 catalyst, and Ce0.5Zr0.5O2 solid solution was formed.

  5. Artificial layered perovskite oxides A(B{sub 0.5}B′{sub 0.5})O{sub 3} as potential solar energy conversion materials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hungru [Environmental Remediation Materials Unit, National Institute for Materials Sciences, Ibaraki 305-0044 (Japan); Umezawa, Naoto [Environmental Remediation Materials Unit, National Institute for Materials Sciences, Ibaraki 305-0044 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan); TU-NIMS Joint Research Center, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin (China)

    2015-02-07

    Perovskite oxides with a d{sup 0} electronic configuration are promising photocatalysts and exhibit high electron mobilities. However, their band gaps are too large for efficient solar energy conversion. On the other hand, transition metal cations with partially filled d{sup n} electronic configurations give rise to visible light absorption. In this study, by using hybrid density functional theory calculations, it is demonstrated that the virtues of the two categories of materials can be combined in perovskite oxide A(B{sub 0.5}B′{sub 0.5})O{sub 3} with a layered B-site ordering along the [001] direction. The electronic structures of the four selected perovskite oxide compounds, La(Ti{sub 0.5}Ni{sub 0.5})O{sub 3}, La(Ti{sub 0.5}Zn{sub 0.5})O{sub 3}, Sr(Nb{sub 0.5}Cr{sub 0.5})O{sub 3}, and Sr(Nb{sub 0.5}Fe{sub 0.5})O{sub 3} are calculated and discussed.

  6. Temperature Evolution of Physical Properties of BaTi0.9(Nb0.5Yb0.5)0.1O3 Lead-Free Ceramic

    Science.gov (United States)

    Abdelkafi, Z.; Abdelmoula, N.; Khemakhem, H.

    2016-11-01

    BaTi0.9(Nb0.5Yb0.5)0.1O3 lead-free ceramic was prepared by a solid-state reaction method. The structure of BaTi0.9(Nb0.5Yb0.5)0.1O3 has been characterized by means of x-ray diffraction, showing the coexistence of cubic (31.1%) and tetragonal (68.9%) phases at room temperature. Dielectric spectroscopy shows that BaTi0.9(Nb0.5Yb0.5)0.1O3 composition sintered at 1380°C exhibits a relaxor behavior with a weak diffuse phase transition obeying a Lorentz-type quadratic relationship. The ferroelectric-paraelectric phase transition T C decreased from 420 K for BaTiO3 to 284 K for BaTi0.9(Nb0.5Yb0.5)0.1O3. The dielectric loss of this ceramic was factor k p, was investigated. d 31 sets a maximum about 32.5 pC/N at temperature of 220 K. Nevertheless, k p undergoes more or less important changes between 120 K and 200 K. Over 200 K, k p degrades very rapidly due to the depoling effect deduced from the hysterisis measurements. Dielectric and structural properties of BaTi0.9(Nb0.5Yb0.5)0.1O3 were confirmed by Raman spectroscopy.

  7. Fate and Disposition of Trichloroethylene in Surface Soils.

    Science.gov (United States)

    1984-01-01

    due to inges- tion of TCE has produced symptoms of gastrointestinal upset, narcosis , and occasional cardiac abnormalities. Reports indicate these...activity up to a point, while a decrease in temperature can curtail activity. Nitrogen is the key nutrient required to decompose organic matter. If the...soil is high in readily available nitrogen , then the microorganisms need no additional source. Conversely, sub- strates with low nitrogen content may

  8. RDX in Plant Tissue: Leading to Humification in Surface Soils

    Science.gov (United States)

    2013-01-01

    aromatics in plant tissue may control or alter plant-related transformations and photodegradation. Bio - available carbon from decaying plant tissue may be...TR-13-4 39 Agronomists have shown that high-organic-matter soils reduce the efficacy of the herbicide 2-chloro-4-ethylamino-6-isopropylamino-1,3,5...resulting in the formation of nitroamine and formaldehyde (Hawari et al. 2000). These intermediates can then be further bio -transformed to either

  9. Critical evaluation of 13C natural abundance techniques to partition soil-surface CO2 efflux

    Science.gov (United States)

    Snell, H.; Midwood, A. J.; Robinson, D.

    2013-12-01

    Soil is the largest terrestrial store of carbon and the flux of CO2 from soils to the atmosphere is estimated at around 98 Pg (98 billion tonnes) of carbon per year. The CO2 efflux from the soil surface is derived from plant root and rhizosphere respiration (autotrophically fuelled) and microbial degradation of soil organic matter (heterotrophic respiration). Heterotrophic respiration is a key determinant of an ecosystem's long-term C balance, but one that is difficult to measure in the field. One approach involves partitioning the total soil-surface CO2 efflux between heterotrophic and autotrophic components; this can be done using differences in the natural abundance stable isotope ratios (δ13C) of autotrophic and heterotrophic CO2 as the end-members of a simple mixing model. In most natural, temperate ecosystems, current and historical vegetation cover (and therefore also plant-derived soil organic matter) is produced from C3 photosynthesis so the difference in δ13C between the autotrophic and heterotrophic CO2 sources is small. Successful partitioning therefore requires accurate and precise measurements of the δ13CO2 of the autotrophic and heterotrophic end-members (obtained by measuring the δ13CO2 of soil-free roots and root-free soil) and of total soil CO2 efflux. There is currently little consensus on the optimum measurement protocols. Here we systematically tested some of the most commonly used techniques to identify and minimise methodological errors. Using soil-surface chambers to sample total CO2 efflux and a cavity ring-down spectrometer to measure δ13CO2 in a partitioning study on a Scottish moorland, we found that: using soil-penetrating collars leads to a more depleted chamber measurement of total soil δ13CO2 as a result of severing roots and fungal hyphae or equilibrating with δ13CO2 at depth or both; root incubations provide an accurate estimate of in-situ root respired δ13CO2 provided they are sampled within one hour; the δ13CO2 from root

  10. Development of a land surface model with coupled snow and frozen soil physics

    Science.gov (United States)

    Wang, Lei; Zhou, Jing; Qi, Jia; Sun, Litao; Yang, Kun; Tian, Lide; Lin, Yanluan; Liu, Wenbin; Shrestha, Maheswor; Xue, Yongkang; Koike, Toshio; Ma, Yaoming; Li, Xiuping; Chen, Yingying; Chen, Deliang; Piao, Shilong; Lu, Hui

    2017-06-01

    Snow and frozen soil are important factors that influence terrestrial water and energy balances through snowpack accumulation and melt and soil freeze-thaw. In this study, a new land surface model (LSM) with coupled snow and frozen soil physics was developed based on a hydrologically improved LSM (HydroSiB2). First, an energy-balance-based three-layer snow model was incorporated into HydroSiB2 (hereafter HydroSiB2-S) to provide an improved description of the internal processes of the snow pack. Second, a universal and simplified soil model was coupled with HydroSiB2-S to depict soil water freezing and thawing (hereafter HydroSiB2-SF). In order to avoid the instability caused by the uncertainty in estimating water phase changes, enthalpy was adopted as a prognostic variable instead of snow/soil temperature in the energy balance equation of the snow/frozen soil module. The newly developed models were then carefully evaluated at two typical sites of the Tibetan Plateau (TP) (one snow covered and the other snow free, both with underlying frozen soil). At the snow-covered site in northeastern TP (DY), HydroSiB2-SF demonstrated significant improvements over HydroSiB2-F (same as HydroSiB2-SF but using the original single-layer snow module of HydroSiB2), showing the importance of snow internal processes in three-layer snow parameterization. At the snow-free site in southwestern TP (Ngari), HydroSiB2-SF reasonably simulated soil water phase changes while HydroSiB2-S did not, indicating the crucial role of frozen soil parameterization in depicting the soil thermal and water dynamics. Finally, HydroSiB2-SF proved to be capable of simulating upward moisture fluxes toward the freezing front from the underlying soil layers in winter.

  11. Assessing soil surface roughness decay during simulated rainfall by multifractal analysis

    Directory of Open Access Journals (Sweden)

    E. Vidal Vázquez

    2008-06-01

    Full Text Available Understanding and describing the spatial characteristics of soil surface microrelief are required for modelling overland flow and erosion. We employed the multifractal approach to characterize topographical point elevation data sets acquired by high resolution laser scanning for assessing the effect of simulated rainfall on microrelief decay. Three soil surfaces with different initial states or composition and rather smooth were prepared on microplots and subjected to successive events of simulated rainfall. Soil roughness was measured on a 2×2 mm2 grid, initially, i.e. before rain, and after each simulated storm, yielding a total of thirteen data sets for three rainfall sequences. The vertical microrelief component as described by the statistical index random roughness (RR exhibited minor changes under rainfall in two out of three study cases, which was due to the imposed wet initial state constraining aggregate breakdown. The effect of cumulative rainfall on microrelief decay was also assessed by multifractal analysis performed with the box-count algorithm. Generalized dimension, Dq, spectra allowed characterization of the spatial variation of soil surface microrelief measured at the microplot scale. These Dq spectra were also sensitive to temporal changes in soil surface microrelief, so that in all the three study rain sequences, the initial soil surface and the surfaces disturbed by successive storms displayed great differences in their degree of multifractality. Therefore, Multifractal parameters best discriminate between successive soil stages under a given rain sequence. Decline of RR and multifractal parameters showed little or no association.

  12. Patterns and scaling properties of surface soil moisture in an agricultural landscape: An ecohydrological modeling study

    Science.gov (United States)

    Korres, W.; Reichenau, T. G.; Schneider, K.

    2013-08-01

    Soil moisture is a key variable in hydrology, meteorology and agriculture. Soil moisture, and surface soil moisture in particular, is highly variable in space and time. Its spatial and temporal patterns in agricultural landscapes are affected by multiple natural (precipitation, soil, topography, etc.) and agro-economic (soil management, fertilization, etc.) factors, making it difficult to identify unequivocal cause and effect relationships between soil moisture and its driving variables. The goal of this study is to characterize and analyze the spatial and temporal patterns of surface soil moisture (top 20 cm) in an intensively used agricultural landscape (1100 km2 northern part of the Rur catchment, Western Germany) and to determine the dominant factors and underlying processes controlling these patterns. A second goal is to analyze the scaling behavior of surface soil moisture patterns in order to investigate how spatial scale affects spatial patterns. To achieve these goals, a dynamically coupled, process-based and spatially distributed ecohydrological model was used to analyze the key processes as well as their interactions and feedbacks. The model was validated for two growing seasons for the three main crops in the investigation area: Winter wheat, sugar beet, and maize. This yielded RMSE values for surface soil moisture between 1.8 and 7.8 vol.% and average RMSE values for all three crops of 0.27 kg m-2 for total aboveground biomass and 0.93 for green LAI. Large deviations of measured and modeled soil moisture can be explained by a change of the infiltration properties towards the end of the growing season, especially in maize fields. The validated model was used to generate daily surface soil moisture maps, serving as a basis for an autocorrelation analysis of spatial patterns and scale. Outside of the growing season, surface soil moisture patterns at all spatial scales depend mainly upon soil properties. Within the main growing season, larger scale

  13. Study on ozone treatment of soil for agricultural application of surface dielectric barrier discharge

    Science.gov (United States)

    Nagatomo, Takuya; Abiru, Tomoya; Mitsugi, Fumiaki; Ebihara, Kenji; Nagahama, Kazuhiro

    2016-01-01

    Recently, application of plasma technologies to the agricultural field has attracted much interest because residual pesticides and excessive nitrogen oxides contained in plants, soil, and groundwater have become a serious issue worldwide. Since almost all of the atmospheric discharge plasma generates ozone, the effects of ozone are among the key factors for their agricultural applications. We have proposed the use of ozone generated using surface barrier discharge plasma for soil disinfection or sterilization. In this work, the ozone consumption coefficient and diffusion coefficient in soil were measured by the ultraviolet absorption method. The pH(H2O) and amount of nitrogen nutrient in soil after ozone diffusion treatment were studied and plant growth was observed simultaneously. The effect of ozone treatment on the amount of DNA in soil was also investigated and compared with that determined from the obtained ozone consumption coefficient.

  14. Fabrication and characterization of highly ordered Ni0.5Zn0.5Fe2O4 nanowire/tube arrays by sol-gel template method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Highly ordered nanowire/tube arrays of Ni0.5Zn0.5Fe2O4 were fabricated by the sol-gel method in the pores of anodic alumina membrane (AAM). Whether nanowires or nanotubes were fabricated depends on immersion time. The immersion time was 15-40 s for nanotubes and over 60 s for nanowires. The topography and crystalline structure of the nanowire arrays were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). It was found that the length and diameter of the Ni0.5Zn0.5Fe2O4 nanowires are related to the thickness of the AAM and the diameter of the pores. The results indicated that the Ni0.5Zn0.5Fe2O4 nanowires are uniform and parallel to each other.

  15. Effect of annealing temperature on photoelectrochemical properties of nanocrystalline MoBi2(Se0.5Te0.5)5 thin films

    Science.gov (United States)

    Salunkhe, Manauti; Pawar, Nita; Patil, P. S.; Bhosale, P. N.

    2014-10-01

    Nanocrystalline MoBi2(Se0.5Te0.5)5 thermoelectric thin films have been deposited on ultrasonically cleaned glass and FTO-coated glass substrates by Arrested Precipitation Technique. The change in properties of MoBi2(Se0.5Te0.5)5 thin films were examined after annealing at the temperature 473 K for 3 h. The structural, morphological, compositional and electrical properties of thin films were characterized by X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, etc. Thermoelectric properties of the thin films have been evaluated by measurements of electrical conductivity and Seebeck coefficient in the temperature range 300-500 K. Our aim is to investigate the effect of annealing on behaviour of MoBi2(Se0.5Te0.5)5 thin films along with photoelectrochemical properties.

  16. KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr- 0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN

    Directory of Open Access Journals (Sweden)

    Sungkono Sungkono

    2015-07-01

    Full Text Available KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr-0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN. Logam paduan Zr-Nb-Fe-Cr dikembangkan sebagai material kelongsong elemen bakar dengan fraksi bakar tinggi untuk reaktor daya maju. Dalam penelitian ini telah dibuat paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr yang mendapat perlakuan panas pada temperatur 650 dan 750°C dengan waktu penahanan 1–2 jam. Tujuan penelitian adalah mendapatkan karakter paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas dan pengerolan dingin yaitu mikrostruktur, struktur kristal dan fasa-fasa yang ada dalam paduan. Hasil penelitian menunjukkan bahwa paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650ºC, 1-2 jam mempunyai struktur butir ekuiaksial dengan ukuran butir bertambah besar seiring dengan bertambahnya waktu penahanan. Sementara itu, pasca perlakuan panas (750ºC, 1-2 jam terjadi perubahan mikrostruktur paduan dari butir ekuiaksial dan kolumnar menjadi butir ekuiaksial lebih besar. Paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650°C, 1 jam dan (750°C, 1 jam tidak dapat dirol dingin dengan reduksi tebal 5 – 10%, sedangkan pasca perlakuan panas (650ºC, 2 jam dan (750°C, 1.5-2 jam mampu menerima deformasi dingin dengan reduksi ketebalan 5-10% tanpa mengalami keretakan. Senyawa Zr2Fe, ZrCr2 dan FeCr teridentifikai dari hasil uji kristalografi paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr.   MICROSTRUCTURE AND PHASE CHARACTERISTICSOF Zr-0.3%Nb-0.5%Fe-0.5%Cr ALLOY POST HEAT TREATMENT AND COLD ROLLING. Zr-Nb-Fe-Cr alloys was developed as fuel elements cladding with high burn up for advanced power reactors. In this research has been made of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy were heat treated with varying temperatures at650 and 750°C for 1 until 2 hours. The objectives of this research was to obtain the character of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment and cold rolling, microstructure nomenclature, crystal structure and phases that presents in the

  17. Different effect of quenching temperature on Fe1+σTe0.5Se0.5 and β-FeSe

    Directory of Open Access Journals (Sweden)

    Zhongnan Guo

    2015-02-01

    Full Text Available In this work, we have demonstrated a different effect on Fe1+σTe0.5Se0.5 and β-FeSe by changing the quenching temperature. Tc is clearly reduced in Fe1+σTe0.5Se0.5 after increasing the quenching temperature from 300 °C to 500 °C, while that of β-FeSe is almost unchanged. Structure refinement indicates that after quenched at 500 °C, FeTe4 tetrahedron exhibits an expansion with the stretched Fe-Te bond, together with the increased amount of interstitial iron. These particular changes on structure are believed to be responsible for the suppression of superconductivity in Fe1+σTe0.5Se0.5.

  18. Oxidation of FGD-CaSO{sub 3} and effect on soil chemical properties when applied to the soil surface

    Energy Technology Data Exchange (ETDEWEB)

    Liming Chen; Cliff Ramsier; Jerry Bigham; Brian Slater; David Kost; Yong Bok Lee; Warren A. Dick [Ohio State University, Wooster, OH (United States). School of Environment and Natural Resources

    2009-07-15

    Use of high-sulfur coal for power generation in the United States requires the removal of sulfur dioxide (SO{sub 2}) produced during burning in order to meet clean air regulations. If SO{sub 2} is removed from the flue gas using a wet scrubber without forced air oxidation, much of the S product created will be sulfite (SO{sub 3}{sup 2-}). Plants take up S in the form of sulfate (SO{sub 2}{sup 2-}). Sulfite may cause damage to plant roots, especially in acid soils. For agricultural uses, it is thought that SO{sub 4}{sup 2-} in flue gas desulfurization (FGD) products must first oxidize to SO{sub 4}{sup 2-} in soils before crops are planted. However, there is little information about the oxidation of SO{sub 3}{sup 2-} in FGD product to SO{sub 4}{sup 2-} under field conditions. An FGD-CaSO{sub 3} was applied at rates of 0, 1.12, and 3.36 Mg ha{sup -1} to the surface of an agricultural soil (Wooster silt loam, Oxyaquic Fragiudalf). The SO{sub 4}{sup 2-} in the surface soil (0-10 cm) was analyzed on days 3, 7, 17, 45, and 61. The distribution of SO{sub 4}{sup 2-} and Ca in the 0-90 cm soil layer was also determined on day 61. Results indicated that SO{sub 3}{sup 2-} in the FGD-CaSO{sub 3} rapidly oxidized to SO{sub 4}{sup 2-} on the field surface during the first week and much of the SO{sub 4}{sup 2-} and Ca moved downward into the 0-50 cm soil layer during the experimental period of two months. It is safe to grow plants in soil treated with FGD-CaSO{sub 3} if the application is made at least three days to several weeks before planting. 20 refs., 6 figs., 4 tabs.

  19. [Distribution and sources of oxygen and sulfur heterocyclic aromatic compounds in surface soil of Beijing, China].

    Science.gov (United States)

    He, Guang-Xiu; Zhang, Zhi-Huan; Peng, Xu-Yang; Zhu, Lei; Lu, Ling

    2011-11-01

    62 surface soil samples were collected from different environmental function zones in Beijing. Sulfur and oxygen heterocyclic aromatic compounds were detected by GC/MS. The objectives of this study were to identify the composition and distribution of these compounds, and discuss their sources. The results showed that the oxygen and sulfur heterocyclic aromatic compounds in the surface soils mainly contained dibenzofuran, methyl- and C2-dibenzofuran series, dibenzothiophene, methyl-, C2- and C3-dibenzothiophene series and benzonaphthothiophene series. The composition and distribution of the oxygen and sulfur heterocyclic aromatic compounds in the surface soil samples varied in the different environmental function zones, of which some factories and the urban area received oxygen and sulfur heterocyclic aromatic compounds most seriously. In Beijing, the degree of contamination by oxygen and sulfur heterocyclic aromatic compounds in the north surface soil was higher than that in the south. There were preferable linear correlations between the concentration of dibenzofuran series and fluorene series, as well as the concentration of dibenzothiophene series and dibenzofuran series. The oxygen and sulfur heterocyclic aromatic compounds in the surface soil were mainly derived from combustion products of oil and coal and direct input of mineral oil, etc. There were some variations in pollution sources of different environmental function zones.

  20. [Distribution Characteristics and Source Identification of Organochlorine Pesticides in Surface Soil in Karst Underground River Basin].

    Science.gov (United States)

    Xie, Zheng-lan; Sun, Yu-chuan; Zhang, Mei; Yu, Qin; Xu, Xin

    2016-03-15

    Six typical surface soil samples were taken in Laolongdong underground river basin, and 20 OCPs were analyzed by gas chromatography equipped with micro-⁶³Ni electron capture detector. The purpose of this study was to investigate the distribution, composition and source of organochlorine pesticides ( OCPs) in the surface soil of Laolongdong underground river basin, and to further evaluate the pollution level. The results showed that 20 OCPs were inordinately detected in the soil samples and the detection rate of 16 OCPs (except for p,p'-DDE, cis-Chlordane, trans-Chlordane, dieldrin) was 100%. Moreover, the CHLs and DDTs were the main contaminants, and there were obvious differences in the concentrations of organochlorine pesticides between different sampling points. The concentration range of total OCPs was 5.57-2,618.57 ng · g⁻¹ with a mean of 467.28 ng · g⁻¹. Compared with other regions both at home and abroad, the concentrations of HCHs and DDTs in the surface soil samples of the studied area were arranged from high to middle levels. The total concentrations of OCPs, HCHs, DDTs and CHLs had a similar variation tendency in spatial distribution, upstream > midstream > downstream, and the concentrations of OCPs in upstream were obviously higher than those in midstream and downstream. Source analysis indicated that the HCHs mainly came from the use of lindane. DDTs in soil came from not only the early residues but also recently illegal use of industrial DDTs and the input of dicofol. In addition, chlordan was mainly from the early residues and atmospheric deposition. Compared with the Environmental Quality Standard for Soils of China and Netherlands, the level of OCPs in Xinli vilage soil was categorized as highly polluted, but the levels of OCPs in Longjing bay, Xia spit, and Zhao courtyard soils were classified as slightly polluted, while the Longjing adjacency and gaozhong temple soils belonged to unpolluted ones.

  1. High redox and performance stability of layered SmBa(0.5)Sr(0.5)Co(1.5)Cu(0.5)O(5+δ) perovskite cathodes for intermediate-temperature solid oxide fuel cells.

    Science.gov (United States)

    Jun, Areum; Shin, Jeeyoung; Kim, Guntae

    2013-12-07

    Cobalt-containing cathodes often encounter problems such as high thermal expansion coefficients (TEC) and poor stability, making them unsuitable for practical use as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). This study focuses on the effects of Cu doping in the Co site of SmBa0.5Sr0.5Co2O5+δ in terms of structural characteristics, electrical properties, electrochemical performance, redox properties, and performance stability as an IT-SOFC cathode material. The TEC value of a SmBa0.5Sr0.5Co1.5Cu0.5O5+δ (SBSCCu50) sample is 12.8 × 10(-6) K(-1), which is lower than that (13.7 × 10(-6) K(-1)) of a SmBa0.5Sr0.5Co2O5+δ (SBSCO) sample at 700 °C. SBSCCu50 showed higher redox stability at lower p(O2) and a more stable cell power output while retaining desirable electrochemical performance, as compared with SBSCO. SBSCCu50 displayed reduced TEC values and enhanced redox and performance stability, as well as satisfactory electrical properties and electrochemical performance under typical fuel cell operating conditions. The results indicate that SBSCCu50 is a promising material as a cathode for IT-SOFCs.

  2. Maxwell-Wagner relaxation and magnetodielectric properties of Bi0.5La0.5MnO3 ceramics

    Science.gov (United States)

    Turik, A. V.; Pavlenko, A. V.; Reznichenko, L. A.

    2016-08-01

    The complex permittivity ɛ = ɛ'- iɛ″ of manganite bismuth-lanthanum Bi0.5La0.5MnO3 ceramics has been measured at temperature T = 78 K in the frequency range f = 200-105 Hz and in the magnetic induction range B = 0-5 T. Dielectric relaxation and the pronounced magnetodielectric effect have been detected. The explanation based on the superposition of Maxwell-Wagner relaxation and the magnetoresistance effect has been proposed.

  3. A Case Study Correlating Innovative Gamma Ray Scanning Detection Systems Data to Surface Soil Gamma Spectrometry Results - 13580

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Shannon; Rodriguez, Rene; Billock, Paul [HydroGeoLogic, Inc., 11107 Sunset Hills Road, Suite 400, Reston, VA 20190 (United States); Lit, Peter [Nomad Science Group, 7738 Nautilus Shell Street, Las Vegas, NV 89139 (United States)

    2013-07-01

    were calculated. From the scanning data, locations with observed Cs-137 ratios exceeding six standard deviations above the mean ratio were mapped in high resolution [2]. Field teams returned to those locations to collect static count measurements using the same detection systems. Soil surface samples were collected at 30 locations and analyzed for Cs-137. An exponential correlation was identified between Cs-137 concentrations in surface soil and field-scanned Cs-137 ratios. The data indicate field minimum detectable concentration (MDC) of Cs-137 at 0.02 Bq/g (0.5 pCi/g) or lower depending on contaminant distribution in soil. (authors)

  4. Speciation and fractionation of heavy metals in soil experimentally contaminated with Pb, Cd, Cu and Zn together and effects on soil negative surface charge

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Speciation of heavy metals in soil subsamplesexperimentally loaded with Pb, Cd, Cu and Zn in orthogonal designwas investigated by sequential extraction, and operationallydefined as water-soluble and exchangeable(SE), weakly specificadsorbed(WSA), Fe and Mn oxides-bound(OX) and organic-bound(ORG).The results show that speciation of heavy metals in the soilsubsamples depended on their kinds. About 90% of Cd and 75% of Znexisted in soil subsamples in the SE fraction. Lead and Cu existedin soil subsamples as SE, WSA and OX fractions simultaneously,although SE was still the major fraction. Organic-bound heavymetals were not clearly apparent in all the soil subsamples. Theconcentration of some heavy metal speciation in soil subsamplesshowed good correlation with ionic impulsion of soil, especiallyfor the SE fraction. Continuous saturation of soil subsamples with0.20 mol/L NH4Cl, which is the first step for determination of thenegative surface charge of soil by the ion retention method, resulted in desorption of certain heavy metals from the soil. Itwas found that the percentage desorption of heavy metals from soilsubsamples depended greatly on pH, the composition and originalheavy metal content of the soil subsamples. However, most of theheavy metals in the soil subsamples were still retained aftermultiple saturation. Compared with the parent soil, the negativesurface charge of soil subsamples loaded with heavy metals did notshow differ significantly from that of the parent one bystatistical analysis. Heavy metals existed in the soil subsamplesmainly as exchangeable and precipitated simultaneously.

  5. Phosphorus Speciation of Forest-soil Organic Surface Layers using P K-edge XANES Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    J Prietzel; J Thieme; D Paterson

    2011-12-31

    The phosphorus (P) speciation of organic surface layers from two adjacent German forest soils with different degree of water-logging (Stagnosol, Rheic Histosol) was analyzed by P K-edge XANES and subsequent Linear Combination Fitting. In both soils, {approx}70% of the P was inorganic phosphate and {approx}30% organic phosphate; reduced P forms such as phosphonate were absent. The increased degree of water-logging in the Histosol compared to the Stagnosol did not affect P speciation.

  6. Preparation and characterization of composites from Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} and polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Q. [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); Hong, R.Y., E-mail: rhong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); Feng, W.G. [Suzhou Nanocomp Inc., Suzhou New District, Suzhou 215011 (China)

    2014-10-01

    Highlights: • Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} was synthesized through the method of co-precipitation. • Inexpensive TiOSO{sub 4} was used as raw material. • The molten salt contributes to better crystal morphology. • Composites with modified particles showed good thermal and dielectric properties. - Abstract: Pure perovskite phase Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} powders were synthesized by facile co-precipitation using inexpensive TiOSO{sub 4} as the raw material. The post-calcining treatment was at the low temperature of 950 °C, which was about 200 °C lower than that of the conventional solid-state method. The effects of two types of precipitation agents on the properties of Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} powders were investigated, and cubic Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} particles were obtained at the optimal conditions. Afterwards, the obtained Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} ceramics were ground into fine ceramic powders, and modified with oleic acid to improve the compatibility with the polystyrene (PS) matrix. The modified ceramic powders were dispersed in PS via solution co-blending to obtain Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3}/PS composites. The structure and morphology of the Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3}/PS composites were characterized through X-ray diffraction (XRD), and scanning electron microscopy (SEM). The SEM images showed that the modified ceramic powders had good dispersion in the PS resin. Moreover, the dielectric and thermal properties of the Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3}/PS composites were investigated, and the results showed that the modified ceramic powders could enhance the dielectric constants and thermal stability of ceramic–polymer composites.

  7. Temperature-Dependent Electron Transport in In0.5Ga0.5P/GaAs Grown by MOVPE

    Institute of Scientific and Technical Information of China (English)

    S. Acar; A. Yíldíz; M. Kasap; M. Bosi

    2007-01-01

    @@ Hall effect measurements in undoped In0.5Ga0.5P/GaAs alloy grown by metal organic vapour-phase epitaxy (MOVPE) have been carried out in the temperature range 15-350K. The experimental results are analysed using a two-band model including conduction band transport calculated using an iterative solution of the Boltzmann equation. A good agreement was obtained between theory and experiment. The impurity contents of In0.5Ga0.5P/GaAs alloy, such as donor density ND, acceptor density NA and donor activation energy εD, were also determined.

  8. Effect of Tb and Al substitution within the rare earth and cobalt sublattices on magnetothermal properties of Dy0.5Ho0.5Co2

    Science.gov (United States)

    Chzhan, V. B.; Tereshina, E. A.; Mikhailova, A. B.; Politova, G. A.; Tereshina, I. S.; Kozlov, V. I.; Ćwik, J.; Nenkov, K.; Alekseeva, O. A.; Filimonov, A. V.

    2017-06-01

    The effect of Tb and Al substitution within the rare earth and cobalt sublattices on structural and magnetothermal properties of Dy0.5Ho0.5Co2 has been studied. Multicomponent Laves phase alloys Tbx(Dy0.5Ho0.5)1-xCo2-yAly (x = 0, 0.3, 0.4, 0.5; y = 0, 0.25) synthesized using high-purity metals have been studied using X-ray diffraction analysis, heat capacity and magnetocaloric measurements. Dy0.5Ho0.5Co2 has a first order phase transition at the Curie temperature TC ≈ 110 K. Both Tb and Al substitution leads to increase of the TC. The increasing Tb content leads to the decreases slightly the MCE and all the transitions near the Curie temperature are of the first order. As for the Al-containing compounds, MCE measurements show that the phase transition type changes from the first to the second-order. The advantage of Tbx(Dy0.5Ho0.5)1-xCo1.75Al0.25 as compared with Al-free alloys is 'table-like' behavior of MCE.

  9. Estimating the amount and distribution of radon flux density from the soil surface in China.

    Science.gov (United States)

    Zhuo, Weihai; Guo, Qiuju; Chen, Bo; Cheng, Guan

    2008-07-01

    Based on an idealized model, both the annual and the seasonal radon ((222)Rn) flux densities from the soil surface at 1099 sites in China were estimated by linking a database of soil (226)Ra content and a global ecosystems database. Digital maps of the (222)Rn flux density in China were constructed in a spatial resolution of 25 km x 25 km by interpolation among the estimated data. An area-weighted annual average (222)Rn flux density from the soil surface across China was estimated to be 29.7+/-9.4 mBq m(-2)s(-1). Both regional and seasonal variations in the (222)Rn flux densities are significant in China. Annual average flux densities in the southeastern and northwestern China are generally higher than those in other regions of China, because of high soil (226)Ra content in the southeastern area and high soil aridity in the northwestern one. The seasonal average flux density is generally higher in summer/spring than winter, since relatively higher soil temperature and lower soil water saturation in summer/spring than other seasons are common in China.

  10. Effects of bionic non-smooth surface on reducing soil resistance to disc ploughing

    Institute of Scientific and Technical Information of China (English)

    CHIRENDE; Benard; SIMALENGA; Timothy; Emmanuel

    2010-01-01

    Past researches have shown that the non-smooth body surfaces of soil burrowing animals help to reduce soil resistance. In this research, this concept of bionic non-smooth surface was applied to disc ploughs and an experiment was conducted in an indoor soil bin to find out the effects of different bionic units on reducing soil resistance to disc ploughing. Horizontal force acting on the disc plough during soil deformation was measured using a 5 kN sensor. Convex and concave bionic units were used and the material used for making convex ones is ultra high molecular weight polyethylene (UHMWPE) which is hydrophobic. From the experiment results, higher or deeper bionic units always resulted in less soil resistance. Convex bionic units gave the highest resistance reduction reaching a maximum of 19% reduction (from 1715.36 N to 1383.65 N) compared to concave bi-onic units. Also, samples with a bionic unit density of 30% gave the highest resistance reduction compared to the other two, which were either plain or had 10% density. In conclusion, the concept of bionic non-smooth units can be applied to disc ploughs in order to reduce soil resistance.

  11. Surface-Correlated Nanophase Iron Metal in Lunar Soils: Petrography and Space Weathering Effects

    Science.gov (United States)

    Keller, Lindsay P.; Wentworth, Susan J.; McKay, David S.

    1998-01-01

    Space weathering is a term used to include all of the processes that act on material exposed at the surface of a planetary or small body. In the case of the Moon, it includes a variety of processes that formed the lunar regolith, caused the maturation of lunar soils, and formed patina on rock surfaces. The processes include micrometeorite impact and reworking, implantation of solar wind and flare particles, radiation damage and chemical effects from solar particles and cosmic rays, interactions with the lunar atmosphere, and sputtering erosion and deposition. Space weathering effects collectively result in a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. Understanding these effects is critical in order to fully integrate the lunar sample collection with remotely sensed data from recent robotic missions (e.g., Lunar Prospector, Clementine, Galileo). Our objective is to determine the origin of space weathering effects in lunar soils through combined electron microscopy and microspectrophotometry techniques applied to individual soil particles from lunar soils. It has been demonstrated that it is the finest size fraction (lunar soils that dominates the optical properties of the bulk soils.

  12. Proton Dissociation from Surfaces of Variable Charge Soil and Minerals

    Institute of Scientific and Technical Information of China (English)

    LUYA-HAI; HUANGCHANG-YONG; 等

    1994-01-01

    Experiments on proton dissociation from the surfaces of goethite,amorphous Al oxide.kaolinite and latosol were carried out,showing amphoteric behavior with reacions of proton dissociation-association on the surfaces and buffering capacity in such a sequence as amorphous Al oxide>latosol>kaolinite>goethite.Dissociation constants of surface proton,pKsa are significantly correlated with surface charge density,which has been proved with an elecrochemical model.The intrinsic constants of proton dissociation,Ksa(int),gained by eptrapolation to zero charge conditions of plots of pKsa against σ0,could be used to estimate the acidity strength of variable charge surfaces,The value of pKsa(int) is 8.08 for goethite,1.2 for a morphous Al oxide,6.62 for kaolinite and 5.32 for latosol.

  13. 10Be inventories in Alpine soils and their potential for dating land surfaces

    Science.gov (United States)

    Egli, Markus; Brandová, Dagmar; Böhlert, Ralph; Favilli, Filippo; Kubik, Peter W.

    2010-07-01

    To exploit natural sedimentary archives and geomorphic landforms it is necessary to date them first. Landscape evolution of Alpine areas is often strongly related to the activities of glaciers in the Pleistocene and Holocene. At sites where no organic matter for radiocarbon dating exists and where suitable boulders for surface exposure dating (using in situ produced cosmogenic nuclides) are absent, dating of soils could give information about the timing of landscape evolution. This paper explores the applicability of soil dating using the inventory of meteoric 10Be in Alpine soils. For this purpose, a set of 6 soil profiles in the Swiss and Italian Alps was investigated. The surface at these sites had already been dated (using the radiocarbon technique or the surface exposure determination using in situ produced 10Be). Consequently, a direct comparison of the ages of the soils using meteoric 10Be and other dating techniques was made possible. The estimation of 10Be deposition rates is subject to severe limitations and strongly influences the obtained results. We tested three scenarios using a) the meteoric 10Be deposition rates as a function of the annual precipitation rate, b) a constant 10Be input for the Central Alps, and c) as b) but assuming a pre-exposure of the parent material. The obtained ages that are based on the 10Be inventory in soils and on scenario a) for the 10Be input agreed reasonably well with the age using surface exposure or radiocarbon dating. The ages obtained from soils using scenario b) produced ages that were mostly too old whereas the approach using scenario c) seemed to yield better results than scenario b). Erosion calculations can, in theory, be performed using the 10Be inventory and 10Be deposition rates. An erosion estimation was possible using scenario a) and c), but not using b). The calculated erosion rates using these scenarios seemed to be plausible with values in the range of 0-57 mm/ky. The dating of soils using 10Be has

  14. 10Be inventories in Alpine soils and their potentiality for dating land surfaces

    Science.gov (United States)

    Egli, Markus; Brandová, Dagmar; Böhlert, Ralph; Favilli, Filippo; Kubik, Peter W.

    2010-05-01

    To exploit natural archives and geomorphic objects it is necessary to date them first. Landscape evolution of Alpine areas is often strongly related to the activities of glaciers in the Pleistocene and Holocene. At sites where no organic matter for radiocarbon dating exists and where suitable boulders for surface exposure dating (using in situ produced cosmogenic nuclides) are absent, dating of soils could give information about the timing of landscape evolution. We explored the applicability of soil dating using the inventory of meteoric Be-10 in Alpine soils. For this purpose, a set of 6 soil profiles in the Swiss and Italian Alps was investigated. The surface at these sites had already been dated (using the radiocarbon technique or surface exposure dating using in situ produced Be-10). Consequently, a direct comparison of the ages of the soils using meteoric Be-10 and other dating techniques was made possible. The estimation of Be-10 deposition rates is subject to severe limitations and strongly influences the obtained results. We tested three scenarios using a) the meteoric Be-10 deposition rates as a function of the annual precipitation rate, b) a constant Be-10 input for the Central Alps and c) as b) but assuming a pre-exposure of the parent material. The obtained ages that are based on the Be-10 inventory in soils and on scenario a) for the Be-10 input agreed reasonably well with the expected age (obtained from surface exposure or radiocarbon dating). The ages obtained from soils using scenario b) produced mostly ages that were too old whereas the approach using scenario c) seemed to yield better results than scenario b). Erosion calculations can, in theory, be performed using the Be-10 inventory and Be-10 deposition rates. An erosion estimation was possible using scenario a) and c), but not using b). The estimated erosion rates are in a reasonable range. The dating of soils using Be-10 has several potential error sources. Analytical errors as well as errors

  15. Assimilation of SMOS brightness temperatures or soil moisture retrievals into a land surface model

    Science.gov (United States)

    De Lannoy, Gabriëlle J. M.; Reichle, Rolf H.

    2016-12-01

    Three different data products from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated separately into the Goddard Earth Observing System Model, version 5 (GEOS-5) to improve estimates of surface and root-zone soil moisture. The first product consists of multi-angle, dual-polarization brightness temperature (Tb) observations at the bottom of the atmosphere extracted from Level 1 data. The second product is a derived SMOS Tb product that mimics the data at a 40° incidence angle from the Soil Moisture Active Passive (SMAP) mission. The third product is the operational SMOS Level 2 surface soil moisture (SM) retrieval product. The assimilation system uses a spatially distributed ensemble Kalman filter (EnKF) with seasonally varying climatological bias mitigation for Tb assimilation, whereas a time-invariant cumulative density function matching is used for SM retrieval assimilation. All assimilation experiments improve the soil moisture estimates compared to model-only simulations in terms of unbiased root-mean-square differences and anomaly correlations during the period from 1 July 2010 to 1 May 2015 and for 187 sites across the US. Especially in areas where the satellite data are most sensitive to surface soil moisture, large skill improvements (e.g., an increase in the anomaly correlation by 0.1) are found in the surface soil moisture. The domain-average surface and root-zone skill metrics are similar among the various assimilation experiments, but large differences in skill are found locally. The observation-minus-forecast residuals and analysis increments reveal large differences in how the observations add value in the Tb and SM retrieval assimilation systems. The distinct patterns of these diagnostics in the two systems reflect observation and model errors patterns that are not well captured in the assigned EnKF error parameters. Consequently, a localized optimization of the EnKF error parameters is needed to further improve Tb or SM retrieval

  16. Optical spectroscopy study of charge density wave order in Sr3Rh4Sn13 and (Sr0.5Ca0.5)3Rh4Sn13

    Science.gov (United States)

    Ban, W. J.; Wang, H. P.; Tseng, C. W.; Kuo, C. N.; Lue, C. S.; Wang, N. L.

    2017-04-01

    We perform optical spectroscopy measurement on single-crystal samples of Sr3Rh4Sn13 and (Sr0.5Ca0.5)3Rh4Sn13. Formation of CDW energy gap was clearly observed for both single-crystal samples when they undergo the phase transitions. The existence of residual Drude components in σ 1( ω) below T CDW indicates that the Fermi surface is only partially gapped in the CDW state. The obtained value of 2Δ/ k B T CDW is roughly 13 for both Sr3Rh4Sn13 and (Sr0.5Ca0.5)3Rh4Sn13 compounds, which is considerably larger than the mean-field value based on the weak-coupling BCS theory. The measurements provide optical evidence for the strong coupling characteristics of the CDW phase transition.

  17. Optical properties and structural investigations of (11-22)-oriented GaN/Al{sub 0.5}Ga{sub 0.5}N quantum wells grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Rosales, Daniel; Gil, Bernard; Bretagnon, Thierry [CNRS, Laboratoire Charles Coulomb, UMR 5221, F-34095 Montpellier (France); Université de Montpellier, Laboratoire Charles Coulomb, UMR 5221, F-34095 Montpellier (France); Brault, Julien; Vennéguès, Philippe; Nemoz, Maud; Mierry, Philippe de; Damilano, Benjamin; Massies, Jean [CNRS Centre de Recherche sur l' Hétéro-Epitaxie et ses Applications, 06560 Valbonne (France); Bigenwald, Pierre [Institut Pascal, Campus des Cézeaux, 24 avenue des Landais, 63171 Aubière Cedex (France)

    2015-07-14

    We have grown (11-22)-oriented GaN/Al{sub 0.5}Ga{sub 0.5}N quantum wells (QWs) using molecular beam epitaxy on GaN (11-22)-oriented templates grown by metal-organic vapor phase epitaxy on m-plane oriented sapphire substrates. The performance of epitaxial growth of GaN/Al{sub 0.5}Ga{sub 0.5}N heterostructures on the semi-polar orientation (11-22) in terms of surface roughness and structural properties, i.e., strain relaxation mechanisms is discussed. In addition, high resolution transmission electron microscopy reveals very smooth QW interfaces. The photoluminescence of such samples are strictly originating from radiative recombination of free excitons for temperatures above 100 K. At high temperature, the population of localized excitons, moderately trapped (5 meV) at low temperature, is negligible.

  18. A soil diffusion-reaction model for surface COS flux: COSSM v1

    Directory of Open Access Journals (Sweden)

    W. Sun

    2015-07-01

    Full Text Available Soil exchange of carbonyl sulfide (COS is the second largest COS flux in terrestrial ecosystems. A novel application of COS is the separation of gross primary productivity (GPP from concomitant respiration. This method requires that soil COS exchange is relatively small and can be well quantified. Existing models for soil COS flux have incorporated empirical temperature and moisture functions derived from laboratory experiments, but not explicitly resolved diffusion in the soil column. We developed a 1-D diffusion-reaction model for soil COS exchange that accounts for COS uptake and production, relates source-sink terms to environmental variables, and has an option to enable surface litter layers. We evaluated the model with field data from a wheat field (Southern Great Plains (SGP, OK, USA and an oak woodland (Stunt Ranch Reserve, CA, USA. The model was able to reproduce all observed features of soil COS exchange such as diurnal variations and sink-source transitions. We found that soil COS uptake is strongly diffusion controlled, and limited by low COS concentrations in the soil if there is COS uptake in the litter layer. The model provides novel insights into the balance between soil COS uptake and production: a higher COS production capacity was required despite lower COS emissions during the growing season compared to the post-senescence period at SGP, and unchanged COS uptake capacity despite the dominant role of COS emissions after senescence. Once there is a database of soil COS parameters for key biomes, we expect the model will also be useful to simulate soil COS exchange at regional to global scales.

  19. A soil diffusion-reaction model for surface COS flux: COSSM v1

    Science.gov (United States)

    Sun, W.; Maseyk, K.; Lett, C.; Seibt, U.

    2015-10-01

    Soil exchange of carbonyl sulfide (COS) is the second largest COS flux in terrestrial ecosystems. A novel application of COS is the separation of gross primary productivity (GPP) from concomitant respiration. This method requires that soil COS exchange is relatively small and can be well quantified. Existing models for soil COS flux have incorporated empirical temperature and moisture functions derived from laboratory experiments but not explicitly resolved diffusion in the soil column. We developed a mechanistic diffusion-reaction model for soil COS exchange that accounts for COS uptake and production, relates source-sink terms to environmental variables, and has an option to enable surface litter layers. We evaluated the model with field data from a wheat field (Southern Great Plains (SGP), OK, USA) and an oak woodland (Stunt Ranch Reserve, CA, USA). The model was able to reproduce all observed features of soil COS exchange such as diurnal variations and sink-source transitions. We found that soil COS uptake is strongly diffusion controlled and limited by low COS concentrations in the soil if there is COS uptake in the litter layer. The model provides novel insights into the balance between soil COS uptake and production: a higher COS production capacity was required despite lower COS emissions during the growing season compared to the post-senescence period at SGP, and unchanged COS uptake capacity despite the dominant role of COS emissions after senescence. Once there is a database of soil COS parameters for key biomes, we expect the model will also be useful to simulate soil COS exchange at regional to global scales.

  20. The influence of surface reflectance anisotropy on estimation of soil properties

    Science.gov (United States)

    Bartholomeus, Harm; Roosjen, Peter; Clevers, Jan

    2014-05-01

    The spatial variation in soil properties is an important factor for agricultural management. Unmanned airborne vehicles (UAV's) equipped with a hyperspectral mapping system may provide these data, but anisotropic reflectance effects may have an influence on the derived soil properties. Besides influencing the reflectance, angular observations may deliver added information about soil properties. We investigated the anisotropic behavior of 59 soil samples with a large variation in soil composition, by measuring their reflectance (350-2500 nm) over 92 different angles using a robot-based laboratory goniometer system. The results show that the anisotropic behavior of the soils influences the measured reflectance significantly, which limits the accurate prediction of soil properties (OM and clay especially). However, prediction accuracies of OM increase when spectra are measured under specific angles. Prediction accuracies further increase when a combination of observation angles is being used. Apart from that, using UAV's the wavelength range is limited to about 1000 nm. In general, this will decrease the model performance, but our results show that this effect can largely be compensated by combining multiple observation angles. Altogether, we demonstrate that surface anisotropy influences the prediction of soil properties negatively. This effect can be reduced by combining spectra acquired under different angles. Moreover, predictions can be improved if combinations of different observation angles are used.

  1. Nutrient Availability in the Surface Horizons of Four Tropical Agricultural Soils in Mali

    Directory of Open Access Journals (Sweden)

    Verloo, MG.

    2002-01-01

    Full Text Available Studies of nutrient availability are important for the understanding and the estimation of soil fertility in areas like West Africa, where low nutrient availability is still one of the major constraints for food production. Physico-chemical soil analyses were used to assess the fertility status of the surface horizon samples of four Malian agricultural soils, (Bougouni, Kangaba, Baguinéda and Gao abbreviated as Bgni, Kgba, Bgda and Gao. Soil texture was sandy loam for Bgni and Kgba, sandy clay loam for Bgda and loamy sand for Gao. Soil pH values varied from moderately acid for Bgda to neutral for the other sites. Organic carbon ranged from very low (for Gao or low (for Bgni and Bgda to medium (for Kgba. Total N, P and CEC were low for the four soils. Available contents of Fe and Mn in all soils, except Gao, were higher than the critical levels while available Cu and Zn contents (except in Kgba were below or close to it. Results indicated that Kgba soil had a better macronutrient status for plant growth than the other sites.

  2. Simple surface foam application enhances bioremediation of oil-contaminated soil in cold conditions.

    Science.gov (United States)

    Jeong, Seung-Woo; Jeong, Jongshin; Kim, Jaisoo

    2015-04-09

    Landfarming of oil-contaminated soil is ineffective at low temperatures, because the number and activity of micro-organisms declines. This study presents a simple and versatile technique for bioremediation of diesel-contaminated soil, which involves spraying foam on the soil surface without additional works such as tilling, or supply of water and air. Surfactant foam containing psychrophilic oil-degrading microbes and nutrients was sprayed twice daily over diesel-contaminated soil at 6 °C. Removal efficiencies in total petroleum hydrocarbon (TPH) at 30 days were 46.3% for landfarming and 73.7% for foam-spraying. The first-order kinetic biodegradation rates for landfarming and foam-spraying were calculated as 0.019 d(-1) and 0.044 d(-1), respectively. Foam acted as an insulating medium, keeping the soil 2 °C warmer than ambient air. Sprayed foam was slowly converted to aqueous solution within 10-12h and infiltrated the soil, providing microbes, nutrients, water, and air for bioaugmentation. Furthermore, surfactant present in the aqueous solution accelerated the dissolution of oil from the soil, resulting in readily biodegradable aqueous form. Significant reductions in hydrocarbon concentration were simultaneously observed in both semi-volatile and non-volatile fractions. As the initial soil TPH concentration increased, the TPH removal rate of the foam-spraying method also increased.

  3. Source apportionment and health risk assessment of trace metals in surface soils of Beijing metropolitan, China.

    Science.gov (United States)

    Chen, Haiyang; Teng, Yanguo; Lu, Sijin; Wang, Yeyao; Wu, Jin; Wang, Jinsheng

    2016-02-01

    Understanding the exposure risks of trace metals in contamination soils and apportioning their sources are the basic preconditions for soil pollution prevention and control. In this study, a detailed investigation was conducted to assess the health risks of trace metals in surface soils of Beijing which is one of the most populated cities in the world and to apportion their potential sources. The data set of metals for 12 elements in 240 soil samples was collected. Pollution index and enrichment factor were used to identify the general contamination characteristic of soil metals. The probabilistic risk model was employed for health risk assessment, and a chemometrics technique, multivariate curve resolution-weighted alternating least squares (MCR-WALS), was applied to apportion sources. Results suggested that the soils in Beijing metropolitan region were contaminated by Hg, Cd, Cu, As, and Pb in varying degree, lying in the moderate pollution level. As a whole, the health risks posed by soil metals were acceptable or close to tolerable. Comparatively speaking, children and adult females were the relatively vulnerable populations for the non-carcinogenic and carcinogenic risks, respectively. Atmospheric deposition, fertilizers and agrochemicals, and natural source were apportioned as the potential sources determining the contents of trace metals in soils of Beijing area with contributions of 15.5%-16.4%, 5.9%-7.7% and 76.0%-78.6%, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Effect of Space Radiation Processing on Lunar Soil Surface Chemistry: X-Ray Photoelectron Spectroscopy Studies

    Science.gov (United States)

    Dukes, C.; Loeffler, M.J.; Baragiola, R.; Christoffersen, R.; Keller, J.

    2009-01-01

    Current understanding of the chemistry and microstructure of the surfaces of lunar soil grains is dominated by a reference frame derived mainly from electron microscopy observations [e.g. 1,2]. These studies have shown that the outermost 10-100 nm of grain surfaces in mature lunar soil finest fractions have been modified by the combined effects of solar wind exposure, surface deposition of vapors and accretion of impact melt products [1,2]. These processes produce surface-correlated nanophase Feo, host grain amorphization, formation of surface patinas and other complex changes [1,2]. What is less well understood is how these changes are reflected directly at the surface, defined as the outermost 1-5 atomic monolayers, a region not easily chemically characterized by TEM. We are currently employing X-ray Photoelectron Spectroscopy (XPS) to study the surface chemistry of lunar soil samples that have been previously studied by TEM. This work includes modification of the grain surfaces by in situ irradiation with ions at solar wind energies to better understand how irradiated surfaces in lunar grains change their chemistry once exposed to ambient conditions on earth.

  5. Global observation-based diagnosis of soil moisture control on land surface flux partition

    Science.gov (United States)

    Gallego-Elvira, Belen; Taylor, Christopher M.; Harris, Phil P.; Ghent, Darren; Veal, Karen L.; Folwell, Sonja S.

    2016-04-01

    Soil moisture plays a central role in the partition of available energy at the land surface between sensible and latent heat flux to the atmosphere. As soils dry out, evapotranspiration becomes water-limited ("stressed"), and both land surface temperature (LST) and sensible heat flux rise as a result. This change in surface behaviour during dry spells directly affects critical processes in both the land and the atmosphere. Soil water deficits are often a precursor in heat waves, and they control where feedbacks on precipitation become significant. State-of-the-art global climate model (GCM) simulations for the Coupled Model Intercomparison Project Phase 5 (CMIP5) disagree on where and how strongly the surface energy budget is limited by soil moisture. Evaluation of GCM simulations at global scale is still a major challenge owing to the scarcity and uncertainty of observational datasets of land surface fluxes and soil moisture at the appropriate scale. Earth observation offers the potential to test how well GCM land schemes simulate hydrological controls on surface fluxes. In particular, satellite observations of LST provide indirect information about the surface energy partition at 1km resolution globally. Here, we present a potentially powerful methodology to evaluate soil moisture stress on surface fluxes within GCMs. Our diagnostic, Relative Warming Rate (RWR), is a measure of how rapidly the land warms relative to the overlying atmosphere during dry spells lasting at least 10 days. Under clear skies, this is a proxy for the change in sensible heat flux as soil dries out. We derived RWR from MODIS Terra and Aqua LST observations, meteorological re-analyses and satellite rainfall datasets. Globally we found that on average, the land warmed up during dry spells for 97% of the observed surface between 60S and 60N. For 73% of the area, the land warmed faster than the atmosphere (positive RWR), indicating water stressed conditions and increases in sensible heat flux

  6. Soil Moisture Active Passive (SMAP) Mission Level 4 Surface and Root Zone Soil Moisture (L4_SM) Product Specification Document

    Science.gov (United States)

    Reichle, Rolf H.; Ardizzone, Joseph V.; Kim, Gi-Kong; Lucchesi, Robert A.; Smith, Edmond B.; Weiss, Barry H.

    2015-01-01

    This is the Product Specification Document (PSD) for Level 4 Surface and Root Zone Soil Moisture (L4_SM) data for the Science Data System (SDS) of the Soil Moisture Active Passive (SMAP) project. The L4_SM data product provides estimates of land surface conditions based on the assimilation of SMAP observations into a customized version of the NASA Goddard Earth Observing System, Version 5 (GEOS-5) land data assimilation system (LDAS). This document applies to any standard L4_SM data product generated by the SMAP Project. The Soil Moisture Active Passive (SMAP) mission will enhance the accuracy and the resolution of space-based measurements of terrestrial soil moisture and freeze-thaw state. SMAP data products will have a noteworthy impact on multiple relevant and current Earth Science endeavors. These include: Understanding of the processes that link the terrestrial water, the energy and the carbon cycles, Estimations of global water and energy fluxes over the land surfaces, Quantification of the net carbon flux in boreal landscapes Forecast skill of both weather and climate, Predictions and monitoring of natural disasters including floods, landslides and droughts, and Predictions of agricultural productivity. To provide these data, the SMAP mission will deploy a satellite observatory in a near polar, sun synchronous orbit. The observatory will house an L-band radiometer that operates at 1.40 GHz and an L-band radar that operates at 1.26 GHz. The instruments will share a rotating reflector antenna with a 6 meter aperture that scans over a 1000 km swath.

  7. A New Empirical Model for Radar Scattering from Bare Soil Surfaces

    Directory of Open Access Journals (Sweden)

    Nicolas Baghdadi

    2016-11-01

    Full Text Available The objective of this paper is to propose a new semi-empirical radar backscattering model for bare soil surfaces based on the Dubois model. A wide dataset of backscattering coefficients extracted from synthetic aperture radar (SAR images and in situ soil surface parameter measurements (moisture content and roughness is used. The retrieval of soil parameters from SAR images remains challenging because the available backscattering models have limited performances. Existing models, physical, semi-empirical, or empirical, do not allow for a reliable estimate of soil surface geophysical parameters for all surface conditions. The proposed model, developed in HH, HV, and VV polarizations, uses a formulation of radar signals based on physical principles that are validated in numerous studies. Never before has a backscattering model been built and validated on such an important dataset as the one proposed in this study. It contains a wide range of incidence angles (18°–57° and radar wavelengths (L, C, X, well distributed, geographically, for regions with different climate conditions (humid, semi-arid, and arid sites, and involving many SAR sensors. The results show that the new model shows a very good performance for different radar wavelengths (L, C, X, incidence angles, and polarizations (RMSE of about 2 dB. This model is easy to invert and could provide a way to improve the retrieval of soil parameters.

  8. Mapping surface soil moisture using an aircraft-based passive microwave instrument: algorithm and example

    Science.gov (United States)

    Jackson, T. J.; Le Vine, David E.

    1996-10-01

    Microwave remote sensing at L-band (21 cm wavelength) can provide a direct measurement of the surface soil moisture for a range of cover conditions and within reasonable error bounds. Surface soil moisture observations are rare and, therefore, the use of these data in hydrology and other disciplines has not been fully explored or developed. Without satellite-based observing systems, the only way to collect these data in large-scale studies is with an aircraft platform. Recently, aircraft systems such as the push broom microwave radiometer (PBMR) and the electronically scanned thinned array radiometer (ESTAR) have been developed to facilitate such investigations. In addition, field experiments have attempted to collect the passive microwave data as part of an integrated set of hydrologic data. One of the most ambitious of these investigations was the Washita'92 experiment. Preliminary analysis of these data has shown that the microwave observations are indicative of deterministic spatial and temporal variations in the surface soil moisture. Users of these data should be aware of a number of issues related to using aircraft-based systems and practical approaches to applying soil moisture estimation algorithms to large data sets. This paper outlines the process of mapping surface soil moisture from an aircraft-based passive microwave radiometer system for the Washita'92 experiment.

  9. Effect of rare-earth (Er and Gd) substitution on the magnetic and multiferroic properties of DyFe0.5Cr0.5O3

    Science.gov (United States)

    Sharma, Mohit K.; Basu, Tathamay; Mukherjee, K.; Sampathkumaran, E. V.

    2016-10-01

    We report the results of our investigations on the influence of partial substitution of Er and Gd for Dy on the magnetic and magnetoelectric properties of DyFe0.5Cr0.5O3, which is known to be a multiferroic system. Magnetic susceptibility and heat capacity data, apart from confirming the occurrence of magnetic transitions at ~121 and 13 K in DyFe0.5Cr0.5O3, bring out that the lower transition temperature only is suppressed by rare-earth substitution. Multiferroic behavior is found to persist in Dy0.4Ln0.6Fe0.5Cr0.5O3 (Ln  =  Er and Gd). There is an evidence for magnetoelectric coupling in all these materials with qualitative differences in its behavior as the temperature is changed across these two transitions. Remnant electric polarization is observed for all the compounds. The most notable observation is that electric polarization is seen to get enhanced as a result of rare-earth substitution with respect to that in DyFe0.5Cr0.5O3. Interestingly, a similar trend is seen in the magnetocaloric effect, consistent with the existence of magnetoelectric coupling. The results thus provide evidence for the tuning of magnetoelectric coupling by rare-earth substitution in this family of oxides.

  10. Spectroscopic and photoluminescence characterization of Dy(3+) in Sr0.5Ca0.5TiO3 phosphor.

    Science.gov (United States)

    Vidyadharan, Viji; Sreeja, E; Jose, Saritha K; Joseph, Cyriac; Unnikrishnan, N V; Biju, P R

    2016-02-01

    The spectroscopic and photoluminescence characteristics of trivalent dysprosium (Dy(3+))-doped Sr0.5Ca0.5TiO3 phosphor materials synthesized via solid-state reaction method were studied. The X-ray diffraction profile confirmed the orthorhombic perovskite structure of the prepared samples. Judd-Ofelt analysis was carried out to obtain the intensity parameters and predicted radiative properties of Sr0.5Ca0.5TiO3:2wt%Dy(3+). The photoluminescence spectrum of Dy(3+)-doped Sr0.5Ca0.5TiO3 showed three emission peaks at 481, 574 and 638 nm corresponding to (4)F9/2 →(6)H15/2, (4)F9/2 →(6)H13/2 and (4)F9/2 →(6)H11/2 transitions respectively. The variation of luminescence intensity with different excitation wavelengths and Dy(3+) concentrations is discussed. The decay profiles of (4)F9/2 excited levels of Dy(3+) ions show bi-exponential behaviour and also a decrease in average lifetime with increase in Dy(3+) concentration. Yellow to blue luminescence intensity ratio, CIE chromaticity co-ordinates and correlated color temperature were also calculated for different concentrations of Dy(3+)-doped Sr0.5Ca0.5TiO3 phosphor at different λex. Copyright © 2015 John Wiley & Sons, Ltd.

  11. Synthesis and properties of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride

    Energy Technology Data Exchange (ETDEWEB)

    Verbovytskyy, Yu. [Physico-Mechanical Institute, NAS of Ukraine, 5 Naukova str., 79601 Lviv (Ukraine); Zhang, J.; Cuevas, F.; Paul-Boncour, V. [Institut de Chimie et des Materiaux de Paris Est, CMTR, UMR 7182, CNRS-UPEC, 2-8 rue H. Dunant, 94320 Thiais (France); Zavaliy, I., E-mail: zavaliy@ipm.lviv.ua [Physico-Mechanical Institute, NAS of Ukraine, 5 Naukova str., 79601 Lviv (Ukraine)

    2015-10-05

    Graphical abstract: Crystal structure of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride. - Highlights: • Preparation of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride by reactive ball milling. • Crystal structure determination by X-ray powder diffraction. • Electrochemical studies of the ball milled MH/Ni electrodes. - Abstract: The Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride with a grain size of 16 nm was prepared by reactive ball milling. Its crystal structure was studied by X-ray powder diffraction. A tetragonal Mg{sub 2}CoH{sub 5} structure type was suggested for the obtained hydride. The decomposition temperature of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} phase was observed at 213 °C. Electrochemical measurements as negative electrode of Ni–MH battery were also performed. Significant improvements can be made by ball-milling the hydride with nickel powder.

  12. Assimilation of ASCAT near-surface soil moisture into the SIM hydrological model over France

    Directory of Open Access Journals (Sweden)

    C. Draper

    2011-12-01

    Full Text Available This study examines whether the assimilation of remotely sensed near-surface soil moisture observations might benefit an operational hydrological model, specifically Météo-France's SAFRAN-ISBA-MODCOU (SIM model. Soil moisture data derived from ASCAT backscatter observations are assimilated into SIM using a Simplified Extended Kalman Filter (SEKF over 3.5 years. The benefit of the assimilation is tested by comparison to a delayed cut-off version of SIM, in which the land surface is forced with more accurate atmospheric analyses, due to the availability of additional atmospheric observations after the near-real time data cut-off. However, comparing the near-real time and delayed cut-off SIM models revealed that the main difference between them is a dry bias in the near-real time precipitation forcing, which resulted in a dry bias in the root-zone soil moisture and associated surface moisture flux forecasts. While assimilating the ASCAT data did reduce the root-zone soil moisture dry bias (by nearly 50%, this was more likely due to a bias within the SEKF, than due to the assimilation having accurately responded to the precipitation errors. Several improvements to the assimilation are identified to address this, and a bias-aware strategy is suggested for explicitly correcting the model bias. However, in this experiment the moisture added by the SEKF was quickly lost from the model surface due to the enhanced surface fluxes (particularly drainage induced by the wetter soil moisture states. Consequently, by the end of each winter, during which frozen conditions prevent the ASCAT data from being assimilated, the model land surface had returned to its original (dry-biased climate. This highlights that it would be more effective to address the precipitation bias directly, than to correct it by constraining the model soil moisture through data assimilation.

  13. Massively Parallel Computation of Soil Surface Roughness Parameters on A Fermi GPU

    Science.gov (United States)

    Li, Xiaojie; Song, Changhe

    2016-06-01

    Surface roughness is description of the surface micro topography of randomness or irregular. The standard deviation of surface height and the surface correlation length describe the statistical variation for the random component of a surface height relative to a reference surface. When the number of data points is large, calculation of surface roughness parameters is time-consuming. With the advent of Graphics Processing Unit (GPU) architectures, inherently parallel problem can be effectively solved using GPUs. In this paper we propose a GPU-based massively parallel computing method for 2D bare soil surface roughness estimation. This method was applied to the data collected by the surface roughness tester based on the laser triangulation principle during the field experiment in April 2012. The total number of data points was 52,040. It took 47 seconds on a Fermi GTX 590 GPU whereas its serial CPU version took 5422 seconds, leading to a significant 115x speedup.

  14. Studies on Electric and Dielectric Properties of Porous Sm0.5Sr0.5CoO3−δ

    Directory of Open Access Journals (Sweden)

    S. S. Pawar

    2013-01-01

    Full Text Available Frequency-dependent electric and dielectric properties of the porous Sm0.5Sr0.5CoO3−δ cathode prepared through conventional combustion synthesis technique were studied in the temperature range 298 K–973 K. The crystal symmetry, space group, and unit cell dimensions were confirmed by analyzing XRD pattern. XRD analysis indicates the formation of a single-phase orthorhombic structure with space group Pnma 62. Scanning electron microscopy technique was used to examine the morphology of the sample. Scanning electron microscopy study showed the formation of porous structure with an average grain size about 850 nm. From the electrical study, it is observed that the conduction in Sm0.5Sr0.5CoO3−δ sample takes place through the hopping mechanism and follows the inverse universal power law. The correlated barrier hopping model was employed successfully to explain the mechanism of charge transport in Sm0.5Sr0.5CoO3−δ. Further, the ac conductivity data was used to evaluate the minimum hopping length and apparent activation energy. The minimum hopping length was found to be ~10−4 times smaller than the grain size of Sm0.5Sr0.5CoO3−δ. The peaking behaviour of the real part of dielectric constant with frequency was explained using the Rezlescu model. This study helps to confirm that the charge transportation in Sm0.5Sr0.5CoO3−δ is due to two types of charge carriers.

  15. Li2Ni(0.5)Mn(0.5)SnO4/C: A Novel Hybrid Composite Electrode for High Rate Applications.

    Science.gov (United States)

    Vellaisamy, Mani; Nallathamby, Kalaiselvi

    2015-09-08

    A novel Li2Ni(0.5)Mn(0.5)SnO4/C composite electrode, existing as a hybrid consisting of monoclinic Li2SnO3 and layered LiNi(0.5)Mn(0.5)O2, has been identified and validated for high capacity and high rate lithium battery applications. Of the components, LiNi(0.5)Mn(0.5)O2 upon discharge forms the corresponding dilithium oxide, viz., Li2Ni(0.5)Mn(0.5)O2, and facilitates the progressive electrochemical performance of the composite electrode. Similarly, Li2SnO3 upon discharge forms Li2O and SnO2, wherein the unacceptable volume expansion related issues of SnO2 are addressed by the buffering activity of Li2O phase. A combination of alloying/dealloying, conversion, and redox mechanism is responsible for the excellent electrochemical behavior of Li2Ni(0.5)Mn(0.5)SnO4/C electrode. With this newer formulation of dilithium stannate composite, a superior capacity of >3000 mAh g(-1) at 100 mA g(-1) current density has been demonstrated. The study opens up a newer gateway for the entry of Li2SnO3·LiM1M2O2 hybrid formulations for exploitation up to 1 A g(-1) rate, thus ensuring the sustainable development of potential electrode materials for high rate applications.

  16. Structural Transformations in High-Capacity Li 2 Cu 0.5 Ni 0.5 O 2 Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Ruther, Rose; Pandian, Amaresh S.; Yan, Pengfei; Weker, Johanna N.; Wang, Chongmin; Nanda, Jagjit

    2017-03-21

    Cathode materials that can cycle > 1 Li+ per transition metal are of substantial interest to increase the overall energy density of lithium-ion batteries. Li2Cu0.5Ni0.5O2 has a very high theoretical capacity of ~ 500 mAh/g assuming both Li+ are cycled reversibly. The Cu2+/3+ and Ni2+/3+/4+ redox couples are also at high voltage, which could further boost the energy density of this system. Despite such promise, Li2Cu0.5Ni0.5O2 undergoes irreversible phase changes during charge (delithiation) that result in large first-cycle irreversible loss and poor long-term cycling stability. Oxygen is evolved before the Cu2+/3+ or Ni3+/4+ transitions are accessed. In this contribution, XRD, TEM, and TXM-XANES are used to follow the chemical and structural changes that occur in Li2Cu0.5Ni0.5O2 during electrochemical cycling. Li2Cu0.5Ni0.5O2 is a solid solution of orthorhombic Li2CuO2 and Li2NiO2, but the structural changes more closely mimic the Li2NiO2 endmember. Li2Cu0.5Ni0.5O2 loses long-range order during charge, but TEM analysis provides clear evidence for particle exfoliation and the transformation from orthorhombic to a partially layered structure. Linear combination fitting and principal component analysis of TXM-XANES are used to map the different phases that emerge during cycling ex situ and in situ. Significant changes in the XANES at the Cu and Ni K-edges correlate with the onset of oxygen evolution.

  17. Influence of vegetation, soil and antecedent soil moisture on the variability of surface runoff coefficients at the plot scale in the eastern alps

    Science.gov (United States)

    Chifflard, P.; Kohl, B.; Markart, G.; Kirnbauer, R.

    2009-04-01

    Modelling the runoff of a catchment in a high spatial resolution, you need to know the potential of a single plot to generate surface runoff. The portion of surface runoff is highly significant for storm runoff events, accordingly, it mainly forms the hydrograph. In this study, the influence of vegetation, soil features and antecedent soil moisture on generating surface runoff at the plot scale have been analysed. To achieve an appropriate fit of the plots, a plot sizes between 50 and 400 m² were chosen. The rainfall intensities ranged between 10 mm/h and 100 mm/h. Based on 260 rain simulations with a transportable sprinkling instrumentation on representative plots in the eastern Alps (Austria, Italy, Germany), including investigations on land-use, vegetation cover and soil physical characteristics, various soil-vegetation complexes and their surface runoff processes have been be analysed. Additionally, we investigated flow paths, travel distance, infiltration hindrance, flow resistance and overland flow velocity. The soil water status was monitored by using TDR-probes, which had been installed in two profiles within the plot in different depths ranging from 5 cm to 40 cm. For every sprinkling experiment, a surface runoff coefficient was calculated as the ratio between total rainfall amount and surface runoff. With this substantial dataset, the regression analysis was used to examine the influence of the hydrological key factors as soil, vegetation and initial soil moisture condition on the distribution functions of the surface runoff coefficient. The first results show that the vegetation cover is very important for the surface runoff. If initial soils are covered by alpine or sub-alpine pioneering vegetation surface runoff can be found very scarce. If these initial soils are covered i.e. by subalpine nardus grasslands the surface runoff coefficients range from 0.1 up to 0.8. On the other hand it can be shown that soils with a high bulk density mainly generate

  18. Modelling and interpreting biologically crusted dryland soil sub-surface structure using automated micropenetrometry

    Science.gov (United States)

    Hoon, Stephen R.; Felde, Vincent J. M. N. L.; Drahorad, Sylvie L.; Felix-Henningsen, Peter

    2015-04-01

    Soil penetrometers are used routinely to determine the shear strength of soils and deformable sediments both at the surface and throughout a depth profile in disciplines as diverse as soil science, agriculture, geoengineering and alpine avalanche-safety (e.g. Grunwald et al. 2001, Van Herwijnen et al. 2009). Generically, penetrometers comprise two principal components: An advancing probe, and a transducer; the latter to measure the pressure or force required to cause the probe to penetrate or advance through the soil or sediment. The force transducer employed to determine the pressure can range, for example, from a simple mechanical spring gauge to an automatically data-logged electronic transducer. Automated computer control of the penetrometer step size and probe advance rate enables precise measurements to be made down to a resolution of 10's of microns, (e.g. the automated electronic micropenetrometer (EMP) described by Drahorad 2012). Here we discuss the determination, modelling and interpretation of biologically crusted dryland soil sub-surface structures using automated micropenetrometry. We outline a model enabling the interpretation of depth dependent penetration resistance (PR) profiles and their spatial differentials using the model equations, σ {}(z) ={}σ c0{}+Σ 1n[σ n{}(z){}+anz + bnz2] and dσ /dz = Σ 1n[dσ n(z) /dz{} {}+{}Frn(z)] where σ c0 and σ n are the plastic deformation stresses for the surface and nth soil structure (e.g. soil crust, layer, horizon or void) respectively, and Frn(z)dz is the frictional work done per unit volume by sliding the penetrometer rod an incremental distance, dz, through the nth layer. Both σ n(z) and Frn(z) are related to soil structure. They determine the form of σ {}(z){} measured by the EMP transducer. The model enables pores (regions of zero deformation stress) to be distinguished from changes in layer structure or probe friction. We have applied this method to both artificial calibration soils in the

  19. GWPs and GTPs for forest bioenergy and products with global coverage at 0.5° x 0.5° spatial resolution

    Science.gov (United States)

    Cherubini, Francesco; Huijbrets, Mark; Kindermann, Georg; Bright, Ryan; Van Zelm, Rosalie; Van Der Velde, Marijn; Strømman, Anders

    2014-05-01

    The effects on climate of various greenhouse gas (GHG) emissions can be aggregated in common units through a variety of emission metrics. The Global Warming Potential (GWP), introduced by the IPCC in 1990, is based on the integrated radiative forcing of a pulse emission divided by an equivalent integration for the reference gas, usually CO2, at an arbitrary time horizon (TH). The Global Temperature change Potential (GTP) is the ratio between the temperature response to a GHG emission pulse at a certain point in time and the temperature response for a reference gas. Other metrics like the integrated GTP (iGTP), TEMP, and metrics embedding economic considerations or a dynamic, target-specific TH are used in the literature. Recent studies developed impulse response functions and emission metrics for CO2 emissions from biomass combustion or oxidation for applications in bioenergy and harvested wood products (HWP) analyses. As the resulting metrics depend on the resource turnover time and hence on site specific characteristics like the type of biomass species, local climate, site productivity and other factors, these metrics are today available only for a limited number of cases and selected locations. In this work, we provide spatially-explicit GWPs and GTPs for bioenergy and HWP sourced from renewable forests with a global coverage of forest areas at a resolution of 0.5 degrees x 0.5 degrees. The Global Forest Model (G4M) developed at IIASA is used to provide the mean annual increments (MAI), rotation periods and above ground carbon of the forests of the globe. G4M uses a dynamic Net Primary Production (NPP) model to simulate how growth rates are affected by changes in temperature, precipitation, radiation, and CO2 concentrations. NPP post harvest dynamics are then modeled using tree-specific functions combined with the grid-specific MAI. Heterotrophic respiration (Rh) is exogenously modeled with the YASSO model. NPP and Rh are then combined in a Net Ecosystem

  20. Landscape position and surface curvature effects on soils developed in the Palouse area, Washington

    Science.gov (United States)

    Girgin, Burhan N.; Frazier, Bruce E.

    1996-11-01

    The Palouse region of eastern Washington is characterized by complex rolling hills with high erosion susceptibility. Various aspect and slope classes along with different soil types also create complex patterns in soil fertility and crop productivity. Division of fields into different units and addressing each unit as a separate management zone has been gaining importance in recent years. Landscape modeling is one of the tools that helps define management zones based on the spatial variability of the soil and topographic characteristics. In addition to comprehensive models, there is an increasing demand for simpler techniques to assist planners with field scale, day-to-day land management. The objective of this study was to develop a simple landscape model within a geographical information systems (GIS) framework to evaluate the effects of spatial variability of topographic factors on soil genesis. For this purpose, a commercial wheat farm was chosen as the research site and a digital elevation model (DEM) of the site was prepared. Landscape parameters such as slope, aspect and tangential curvature were calculated. GIS overlay of these values were georeferenced and combined with other data layers such as soil maps and air photos. Soil samples were collected on three different transects and representative pits were opened for further evaluation of soil properties. Depth to E horizon was measured for all sampling locations. Results indicate that spatial distribution of E horizon can be estimated by surface curvature, slope and aspect. Study also shows that contrasting soils that are in close proximity to each other, too close to be separated on conventional soil maps, can be detected with the help of landscape parameters. Big map units that extend over several hillslope positions can be further divided into smaller units to receive separate agricultural management based on soil, water relationships defined by these landscape parameters.

  1. STIR Proposal For Research Area 2.1.2 Surface Energy Balance: Transient Soil Density Impacts Land Surface Characteristics and Characterization

    Science.gov (United States)

    2015-12-22

    SECURITY CLASSIFICATION OF: Soil density is commonly treated as static in studies on land surface property dynamics. Magnitudes of errors associated...properties, and ii) evaluate impact of changing soil density on surface energy balance and heat and water transfer. Six soil properties were...ABSTRACT 2. REPORT TYPE 17. LIMITATION OF ABSTRACT 15. NUMBER OF PAGES 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 5c. PROGRAM ELEMENT

  2. The most massive galaxies in clusters are already fully grown at z ∼ 0.5

    Science.gov (United States)

    Oldham, L. J.; Houghton, R. C. W.; Davies, Roger L.

    2017-02-01

    By constructing scaling relations for galaxies in the massive cluster MACSJ0717.5 at z = 0.545 and comparing with those of Coma, we model the luminosity evolution of the stellar populations and the structural evolution of the galaxies. We calculate magnitudes, surface brightnesses and effective radii using Hubble Space Telescope (HST)/ACS images and velocity dispersions using Gemini/GMOS spectra, and present a catalogue of our measurements for 17 galaxies. We also generate photometric catalogues for ∼3000 galaxies from the HST imaging. With these, we construct the colour-magnitude relation, the Fundamental Plane, the mass-to-light versus mass relation, the mass-size relation and the mass-velocity dispersion relation for both clusters. We present a new, coherent way of modelling these scaling relations simultaneously using a simple physical model in order to infer the evolution in luminosity, size and velocity dispersion as a function of redshift, and show that the data can be fully accounted for with this model. We find that (a) the evolution in size and velocity dispersion undergone by these galaxies between z ∼ 0.5 and z ∼ 0 is mild, with Re(z) ∼ (1 + z)-0.40 ± 0.32 and σ(z) ∼ (1 + z)0.09 ± 0.27, and (b) the stellar populations are old, ∼10 Gyr, with a ∼3 Gyr dispersion in age, and are consistent with evolving purely passively since z ∼ 0.5 with Δ log M/L_B = -0.55_{-0.07}^{+0.15} z. The implication is that these galaxies formed their stars early and subsequently grew dissipationlessly so as to have their mass already in place by z ∼ 0.5, and suggests a dominant role for dry mergers, which may have accelerated the growth in these high-density cluster environments.

  3. A new elliptic-parabolic yield surface model revised by an adaptive criterion for granular soils

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An adaptive criterion for shear yielding as well as shear failure of soils is proposed in this paper to address the fact that most criteria,including the Mohr-Coulomb criterion,the Lade criterion and the Matsuoka-Nakai criterion,cannot agree well with the experimental results when the value of the intermediate principal stress parameter is too big.The new criterion can adjust an adaptive parameter based on the experimental results in order to make the theoretical calculations fit the test results more accurately.The original elliptic-parabolic yield surface model can capture both soil contraction and dilation behaviors.However,it normally over-predicts the soil strength due to its application of the Extended Mises criterion.A new elliptic-parabolic yield surface mode is presented in this paper,which introduces the adaptive criterion in three-dimensional principal stress space.The new model can well model the stress-strain behavior of soils under general stress conditions.Compared to the original model which can only simulate soil behavior under triaxial compression conditions,the new model can simulate soil behaviors under both triaxial compression conditions and general stress conditions.

  4. Space Weathering Effects in Lunar Soils: The Roles of Surface Exposure Time and Bulk Chemical Composition

    Science.gov (United States)

    Zhang, Shouliang; Keller, Lindsay P.

    2011-01-01

    Space weathering effects on lunar soil grains result from both radiation-damaged and deposited layers on grain surfaces. Typically, solar wind irradiation forms an amorphous layer on regolith silicate grains, and induces the formation of surficial metallic Fe in Fe-bearing minerals [1,2]. Impacts into the lunar regolith generate high temperature melts and vapor. The vapor component is largely deposited on the surfaces of lunar soil grains [3] as is a fraction of the melt [4, this work]. Both the vapor-deposits and the deposited melt typically contain nanophase Fe metal particles (npFe0) as abundant inclusions. The development of these rims and the abundance of the npFe0 in lunar regolith, and thus the optical properties, vary with the soil mineralogy and the length of time the soil grains have been exposed to space weathering effects [5]. In this study, we used the density of solar flare particle tracks in soil grains to estimate exposure times for individual grains and then perform nanometer-scale characterization of the rims using transmission electron microscopy (TEM). The work involved study of lunar soil samples with different mineralogy (mare vs. highland) and different exposure times (mature vs. immature).

  5. Soil Surface Leak Detection From Carbon Storage Sites Using ∆(CO2:O2) Measurements

    Science.gov (United States)

    Alam, M. M.; Norman, A. L.; Layzell, D. B.

    2015-12-01

    The early detection and remediation of CO2 leaks from Carbon Capture and Storage (CCS) sites is essential for the safety and public support of the technology. A model that integrates gas diffusion, mass flow and biological processes in soils was developed and used to predict the ∆CO2 and ∆O2 concentration differential between the soil surface and the bulk atmosphere under a wide range of environmental conditions that include temperature, soil gas and water content, soil respiratory quotient and rate of O2 uptake, soil porosity and CO2 leakage rate. The results predicted that measurement of ∆(CO2:O2) measurements at the soil surface relative to air should be able to detect a CCS leak as low as 2 µmol/m2/sec. To test this hypothesis, a gas analysis system was designed and constructed. It should allow a series of experiments under controlled conditions to test all aspects of the model. It is hoped that the results from this work will ultimately lead to the development of a new instrument and protocol for the early detection of CO2 leaks from a geological storage sites.

  6. Biological soil crust and disturbance controls on surface hydrology in a semi-arid ecosystem

    Science.gov (United States)

    Faist, Akasha M; Herrick, Jeffrey E.; Belnap, Jayne; Van Zee, Justin W; Barger, Nichole N

    2017-01-01

    Biological soil crust communities (biocrusts) play an important role in surface hydrologic processes in dryland ecosystems, and these processes may then be dramatically altered with soil surface disturbance. In this study, we examined biocrust hydrologic responses to disturbance at different developmental stages on sandy soils on the Colorado Plateau. Our results showed that all disturbance (trampling, scalping and trampling+scalping) of the early successional light cyanobacterial biocrusts generally reduced runoff. In contrast, trampling well-developed dark-cyano-lichen biocrusts increased runoff and sediment loss relative to intact controls. Scalping did not increase runoff, implying that soil aggregate structure was important to the infiltration process. Well-developed, intact dark biocrusts generally had lower runoff, low sediment loss, and highest aggregate stability whereas the less-developed light biocrusts were highest in runoff and sediment loss when compared to the controls. These results suggest the importance of maintaining the well-developed dark biocrusts, as they are beneficial for lowering runoff and reducing soil loss and redistribution on the landscape. These data also suggest that upslope patches of light biocrust may either support water transport to downslope vegetation patches or alternatively this runoff may place dark biocrust patches at risk of disruption and loss, given that light patches increase runoff and thus soil erosion potential.

  7. Non-destructive image analysis of soil surface porosity and bulk density dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Pires, L.F., E-mail: lfpires@uepg.b [Laboratory of Soil Physics and Environmental Sciences, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900, Ponta Grossa, PR (Brazil); Cassaro, F.A.M. [Laboratory of Soil Physics and Environmental Sciences, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900, Ponta Grossa, PR (Brazil); Bacchi, O.O.S.; Reichardt, K. [Laboratory of Soil Physics, Center for Nuclear Energy in Agriculture, USP/CENA, C.P. 96, C.E.P. 13.400-970, Piracicaba, SP (Brazil)

    2011-04-15

    A gamma-ray computed tomography (CT) scanner was used to evaluate changes in the structure of clayey soil samples with surface compaction submitted to wetting and drying (W-D) cycles. The obtained results indicate that W-D cycles promoted an increasing of about 10% in soil porosity with a decreasing of about 6% in soil bulk density of this compacted region. With the use of the CT it was also possible to define the thickness of the compacted region that in our case was of about 8.19 mm. This last information is very important, for instance, to estimate hydraulic parameters in infiltration models. Finally, CT analysis showed that the compacted region remained at the surface samples, even after the application of the W-D cycles. -- Research highlights: {yields} Gamma-ray tomography allowed non-destructive analysis of soil bulk density and porosity changes. {yields} Soil porosity increased about 10% with the wetting and drying cycles. {yields} Soil bulk density in the compacted region decreased about 6% with the wetting and drying cycles. {yields} Detailed bulk density and porosity analysis changes were obtained for layers of 1.17 mm.

  8. A Comparison of Land Surface Model Soil Hydraulic Properties Estimated by Inverse Modeling and Pedotransfer Functions

    Science.gov (United States)

    Gutmann, Ethan D.; Small, Eric E.

    2007-01-01

    Soil hydraulic properties (SHPs) regulate the movement of water in the soil. This in turn plays an important role in the water and energy cycles at the land surface. At present, SHPS are commonly defined by a simple pedotransfer function from soil texture class, but SHPs vary more within a texture class than between classes. To examine the impact of using soil texture class to predict SHPS, we run the Noah land surface model for a wide variety of measured SHPs. We find that across a range of vegetation cover (5 - 80% cover) and climates (250 - 900 mm mean annual precipitation), soil texture class only explains 5% of the variance expected from the real distribution of SHPs. We then show that modifying SHPs can drastically improve model performance. We compare two methods of estimating SHPs: (1) inverse method, and (2) soil texture class. Compared to texture class, inverse modeling reduces errors between measured and modeled latent heat flux from 88 to 28 w/m(exp 2). Additionally we find that with increasing vegetation cover the importance of SHPs decreases and that the van Genuchten m parameter becomes less important, while the saturated conductivity becomes more important.

  9. Assimilation of ASCAT near-surface soil moisture into the French SIM hydrological model

    Directory of Open Access Journals (Sweden)

    C. Draper

    2011-06-01

    Full Text Available The impact of assimilating near-surface soil moisture into the SAFRAN-ISBA-MODCOU (SIM hydrological model over France is examined. Specifically, the root-zone soil moisture in the ISBA land surface model is constrained over three and a half years, by assimilating the ASCAT-derived surface degree of saturation product, using a Simplified Extended Kalman Filter. In this experiment ISBA is forced with the near-real time SAFRAN analysis, which analyses the variables required to force ISBA from relevant observations available before the real time data cut-off. The assimilation results are tested against ISBA forecasts generated with a higher quality delayed cut-off SAFRAN analysis. Ideally, assimilating the ASCAT data will constrain the ISBA surface state to correct for errors in the near-real time SAFRAN forcing, the most significant of which was a substantial dry bias caused by a dry precipitation bias. The assimilation successfully reduced the mean root-zone soil moisture bias, relative to the delayed cut-off forecasts, by close to 50 % of the open-loop value. The improved soil moisture in the model then led to significant improvements in the forecast hydrological cycle, reducing the drainage, runoff, and evapotranspiration biases (by 17 %, 11 %, and 70 %, respectively. When coupled to the MODCOU hydrogeological model, the ASCAT assimilation also led to improved streamflow forecasts, increasing the mean discharge ratio, relative to the delayed cut off forecasts, from 0.68 to 0.76. These results demonstrate that assimilating near-surface soil moisture observations can effectively constrain the SIM model hydrology, while also confirming the accuracy of the ASCAT surface degree of saturation product. This latter point highlights how assimilation experiments can contribute towards the difficult issue of validating remotely sensed land surface observations over large spatial scales.

  10. X-ray photoelectron spectroscopic study of direct reforming catalysts Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) for high temperature-operating solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Keunsoo [Department of Engine Research, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon 305-343 (Korea, Republic of); Jeong, Jihoon [Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Azad, Abul K. [Faculty of Integrated Technologies, University Brunei Darussalam, Jalan Tunku Link, Gadong BE1410 (Brunei Darussalam); Jin, Sang Beom [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of); Kim, Jung Hyun, E-mail: jhkim2011@hanbat.ac.kr [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of)

    2016-03-01

    Graphical abstract: Measured Ti 2p peaks and deconvolution peaks of Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} under oxidizing condition (left) and NSTM under reducing condition (right). - Highlights: • Chemical states of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm) were analyzed. • Charge compensation occurred with the reduction of Mn and Ti. • The Nd substitution effect allowed some Ti to convert into a metallic behavioral component. • NSTM and SSTM had a large amount of lattice oxygen; however, LSTM retained a large quantity of adsorbed oxygen. - Abstract: Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}; Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}, some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} from the O 1s spectra; a high portion of lattice oxygen was observed in both Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (NSTM) and Sm{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O

  11. Structural, thermal and electrical conductivity characteristics of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm) complex perovskites as anode materials for solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jihoon [Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 5, Hwarang-Ro 14-Gil, Seongbuk-Gu, Seoul 136-791 (Korea, Republic of); Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Azad, Abul K. [Faculty of Integrated Technologies, University Brunei Darussalam, Jalan Tunku Link, Gadong, BE 1410 (Brunei Darussalam); Schlegl, Harald [School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST (United Kingdom); Kim, Byungjun [Department of Applied Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yuseong-Gu, Daejeon 305-719 (Korea, Republic of); Baek, Seung-Wook [Center for Energy Materials Metrology, Division of Industrial Metrology, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-Ro, Yuseong-Gu, Daejeon 305-340 (Korea, Republic of); Kim, Keunsoo [Department of Engine Research, Korea Institute of Machinery and Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Kang, Hyunil [Department of Electrical Engineering, Hanbat National University, 125, Dongseo-Daero, Yuseong-Gu, Daejeon 305-719 (Korea, Republic of); Kim, Jung Hyun, E-mail: jhkim2011@hanbat.ac.kr [Department of Applied Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yuseong-Gu, Daejeon 305-719 (Korea, Republic of)

    2015-03-15

    The Ti and Mn replaced complex perovskites, Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm), were reported as potential anode materials for high temperature-operating solid oxide fuel cells (HT-SOFCs). For the present research study, synthesis, crystallographic, thermal and electrical conductivity properties of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} complex perovskites were investigated using X-ray diffraction (XRD), Rietveld method, thermogravimetric analysis (TGA) and electrical conductivity to apply these oxide materials for the HT-SOFC anode materials. XRD results showed that Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} oxide systems synthesized as single phases did not react with 8 mol% yttria stabilized zirconia (8YSZ) and 10 mol% Gd-doped cerium oxide (CGO91) up to 1500 °C and did not decompose under dry 3.9% hydrogen at 850 °C. The crystal structures of La{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (LSTM), Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (NSTM) and Sm{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (SSTM) showed orthorhombic symmetry with the space group Pbnm and SSTM showed a more distorted structure. Thermogravimetric analysis (TGA) proved weight gains in these three sample occurred under oxidizing conditions and weight loss under reducing conditions. Electrical conductivity values of NSTM were higher than those of LSTM and SSTM under oxidizing and reducing conditions. - Graphical abstract: The B-site cations (Ti/Mn) are surrounded by regular octahedra of oxygen in Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}(NSTM). These octahedra are linked together in a corner sharing three dimensional framework, while Nd/Sr ion occupies 12-coordinated A-site between these octahedra. The Ti/Mn–O{sub 6} octahedra are elongated along the c-axis. The crystal structure distortion was due to the smaller ionic radius of the A-site cations, which force the (Ti

  12. Bacteria-mineral interactions in soil and their effect on particle surface properties

    Science.gov (United States)

    Miltner, Anja; Achtenhagen, Jan; Goebel, Marc-Oliver; Bachmann, Jörg; Kästner, Matthias

    2015-04-01

    Interactions between bacteria or their residues and mineral surfaces play an important role for soil processes and properties. It is well known that bacteria tend to grow attached to surfaces and that they get more hydrophobic when grown under stress conditions. In addition, bacterial and fungal biomass residues have recently been shown to contribute to soil organic matter formation. The attachment of bacteria or their residues to soil minerals can be expected to modify the surface properties of these particles, in particular the wettability. We hypothesize that the extent of the effect depends on the surface properties of the bacteria, which change depending on environmental conditions. As the wettability of soil particles is crucial for the distribution and the availability of water, we investigated the effect of both living cells and bacterial residues (cell envelope fragments and cytosol) on the wettability of model mineral particles in a simplified laboratory system. We grew Pseudomonas putida cells in mineral medium either without (unstressed) or with additional 1.5 M NaCl (osmotically stressed). After 2 h of incubation, the cells were disintegrated by ultrasonic treatment. Different amounts of either intact cells, cell envelope fragments or cytosol (each corresponding to 108, 109, or 1010 cells per gram of mineral) were mixed with quartz sand, quartz silt or kaolinite. The bacteria-mineral associations were air-dried for 2 hours and analyzed for their contact angle. We found that the surfaces of osmotically stressed cells were more hydrophobic than the surfaces of unstressed cells and that the bacteria-mineral associations had higher contact angles than the pure minerals. A rather low surface coverage (~10%) of the mineral surfaces by bacteria was sufficient to increase the contact angle significantly, and the different wettabilities of stressed and unstressed cells were reflected in the contact angles of the bacteria-mineral associations. The increases in

  13. Temperature dependent structures and properties of Bi0.5Na0.5TiO3-based lead free piezoelectric composite.

    Science.gov (United States)

    Zhang, Ji; Sun, Lei; Geng, Xiao-Yu; Zhang, Bin-Bin; Yuan, Guo-Liang; Zhang, Shan-Tao

    2016-07-05

    The thermal depolarization around 100 °C of the Bi0.5Na0.5TiO3-based piezoelectric solid solutions leads to the disappearance of macroscopic ferroelectric/piezoelectric properties and remains a long-standing obstacle for their actual applications. In this communication, we report lead-free piezoelectric composites of 0.94Bi0.5Na0.5TiO3-0.06BaTiO3:0.5ZnO (BNT-6BT:0.5ZnO, where 0.5 is the mole ratio of ZnO to BNT-6BT) with deferred thermal depolarization, which is experimentally confirmed by systematic temperature dependent dielectric, ferroelectric, piezoelectric measurements. Especially, based on temperature dependent X-ray diffraction measurements on unpoled and poled samples, thermal depolarization is confirmed to have no relationship with the structural phase transition, the possible mechanism for the deferred thermal depolarization is correlated with the ZnO-induced local electric field which can suppress the depolarization field. We believe our results may be helpful for understanding the origin of thermal depolarization in BNT-based piezoelectric materials, and thus provide an effective way to overcoming this obstacle.

  14. Studying the effects of Zr-doping in (Bi0.5Na0.5)TiO3via diffraction and spectroscopy.

    Science.gov (United States)

    Blanchard, Peter E R; Liu, Samuel; Kennedy, Brendan J; Ling, Chris D; Zhang, Zhaoming; Avdeev, Maxim; Jang, Ling-Yun; Lee, Jyh-Fu; Pao, Chih-Wen; Chen, Jeng-Lung

    2014-12-14

    The structural properties of (Bi0.5Na0.5)Ti1-xZrxO3 (where 0 ≤ x ≤ 0.7) have been investigated using powder diffraction and X-ray absorption spectroscopy. Diffraction measurements on (Bi0.5Na0.5)TiO3 confirm that both monoclinic Cc and rhombohedral R3c phases are present at room temperature. Doping small amounts of Zr into the B site of (Bi0.5Na0.5)TiO3 initially stabilizes the rhombohedral phase before the orthorhombic Pnma phase begins to form at x = 0.5. Analysis of the Ti K-edge and Zr L3-edge XANES spectra show that the crystallographic phase change has very little effect on the local structure of Ti(4+)/Zr(4+) cations, suggesting that there is little change in the cation off-center displacement within the BO6 octahedra with each successive phase change.

  15. A Gel-Polymer Sn-C/LiMn0.5Fe0.5PO4 Battery Using a Fluorine-Free Salt.

    Science.gov (United States)

    Di Lecce, Daniele; Fasciani, Chiara; Scrosati, Bruno; Hassoun, Jusef

    2015-09-30

    Safety and environmental issues, because of the contemporary use of common liquid electrolytes, fluorinated salts, and LiCoO2-based cathodes in commercial Li-ion batteries, might be efficiently mitigated by employing alternative gel-polymer battery configurations and new electrode materials. Herein we study a lithium-ion polymer cell formed by combining a LiMn0.5Fe0.5PO4 olivine cathode, prepared by simple solvothermal pathway, a nanostructured Sn-C anode, and a LiBOB-containing PVdF-based gel electrolyte. The polymer electrolyte, here analyzed in terms of electrochemical stability by impedance spectroscopy (EIS) and voltammetry, reveals full compatibility for cell application. The LiBOB electrolyte salt and the electrochemically delithiaded Mn0.5Fe0.5PO4 have a higher thermal stability compared to conventional LiPF6 and Li0.5CoO2, as confirmed by thermogravimetric analysis (TGA) and by galvanostatic cycling at high temperature. LiMn0.5Fe0.5PO4 and Sn-C, showing in lithium half-cell a capacity of about 120 and 350 mAh g(-1), respectively, within the gelled electrolyte configuration are combined in a full Li-ion polymer battery delivering a stable capacity of about 110 mAh g(-1), with working voltage ranging from 2.8 to 3.6 V.

  16. Charge and spin order in C a0.5B i0.5Fe O3 : Idle spins and frustration in the charge-disproportionated state

    Science.gov (United States)

    Denis Romero, Fabio; Hosaka, Yoshiteru; Ichikawa, Noriya; Saito, Takashi; McNally, Graham; Attfield, J. Paul; Shimakawa, Yuichi

    2017-08-01

    The perovskite C a0.5B i0.5Fe O3 undergoes a remarkable sequence of charge-disproportionation (CD) and charge-transfer (CT) transitions on cooling due to competing electronic instabilities: C a0.5Bi3 +0.5F e3.5 +O3→C a0.5Bi3 +0.5Fe3 +0.67Fe4.5 +0.33O3(CD phase ) →C a0.5Bi3 +0.25Bi5 +0.25F e3 +O3(CT phase ) . The accompanying changes in charge and spin ordering have been determined from neutron diffraction and physical property measurements. The CT phase adopts a simple G -type antiferromagnetic structure of F e3 + spins but the CD phase adopts an unusual charge and magnetic arrangement in which F e3 + spins are antiferromagnetically ordered but the F e4.5 + moments have no long-range order due to magnetic frustration and form a spin glass at low temperatures.

  17. Characterization of Cu3P phase in Sn3.0Ag0.5Cu0.5P/Cu solder joints

    Institute of Scientific and Technical Information of China (English)

    Jian-xun Chen; Xing-ke Zhao; Xu-chen Zou; Ji-hua Huang; Hai-chun Hu; Hai-lian Luo

    2014-01-01

    This article reports the effects of phosphorus addition on the melting behavior, microstructure, and mechanical properties of Sn3.0Ag0.5Cu solder. The melting behavior of the solder alloys was determined by differential scanning calorimetry. The interfacial micro-structure and phase composition of solder/Cu joints were studied by scanning electron microscopy and energy dispersive spectrometry. Thermodynamics of Cu-P phase formation at the interface between Sn3.0Ag0.5Cu0.5P solder and the Cu substrate was characterized. The results indicate that P addition into Sn3.0Ag0.5Cu solder can change the microstructure and cause the appearance of rod-like Cu3P phase which is distributed randomly in the solder bulk. The Sn3.0Ag0.5Cu0.5P joint shows a mixture of ductile and brittle fracture after shear test-ing. Meanwhile, the solidus temperature of Sn3.0Ag0.5Cu solder is slightly enhanced with P addition.

  18. Thermal Stability and Humidity Resistance of ScTaO_4 Modified(K_(0.5)Na_(0.5))NbO_3 Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHENG Li-Mei; WANG Jin-Feng; WANG Chun-Ming; WU Qing-Zao; ZANG Guo-Zhong

    2009-01-01

    Lead-free(Na_(0.5)K_(0.5))NbO_3-xmol% ScTaO_4(x = 0-1.5)ceramics are prepared using the conventional solid-state reaction method and their properties are investigated in detail.The results indicate that the piezoelectric properties and density are improved by the introduction of ScTaO_4.Due to the high orthorhombic-tetragonal phase transition temperature T_(O-T)(around 200℃),stable piezoelectric properties against temperature are obtained.In a wide temperature range of 15-160° C,k_p of the(Na_(0.5)K_(0.5))NbO_3-0.5 mol% ScTaO_4 ceramic remains almost unchanged and d_(31) increases slightly from 59pC/N to 71pC/N.The deliquescent problem is effectively solved by the addition of ScTaO_4.The piezoelectric properties of ScTaO_4 modified(Na_(0.5)K_(0.5))NbO_3 ceramics show no obvious reduction and dielectric loss increases slightly after 120 h of immersion.From the analysis,it is suggested that the density is an important factor that improves the humidity resistance of the specimens.

  19. Soil fertility, nutrition and yield of maize and barley with gypsum application on soil surface in no-till

    Directory of Open Access Journals (Sweden)

    Leandro Michalovicz

    2014-10-01

    Full Text Available Annual crop yield and nutrition have shown differentiated responses to modifications in soil chemical properties brought about by gypsum application. The aim of this study was to evaluate the effect of gypsum application rates on the chemical properties of a Latossolo Bruno (Clayey Oxisol, as well as on the nutrition and yield of a maize-barley succession under no-till. The experiment was set up in November 2009 in Guarapuava, Parana, Brazil, applying gypsum rates of 0.0, 1.5, 3.0, 4.5, and 6.0 Mg ha-1 to the soil surface upon sowing maize, with crop succession of barley. Gypsum application decreased the levels of Al3+ and Mg2+ in the 0.0-0.1 m layer and increased soil pH in the layers from 0.2-0.6 m depth. Gypsum application has increased the levels of Ca2+ in all soil layers up to 0.6 m, and the levels of S-SO4(2- up to 0.8 m. In both crops, the leaf concentrations of Ca and S were increased while Mg concentrations have decreased as a function of gypsum rates. There was also an effect of gypsum rates on grain yield, with a quadratic response of maize and a linear increase for barley. Yield increases were up to 11 and 12 % in relation to control for the maximum technical efficiency (MTE rates of 3.8 and 6.0 Mg ha-1 of gypsum, respectively. Gypsum application improved soil fertility in the profile, especially in the subsurface, as well as plant nutrition, increasing the yields of maize and barley.

  20. Assessment of heavy metal contamination in roadside surface soil and vegetation from the West Bank.

    Science.gov (United States)

    Swaileh, K M; Hussein, R M; Abu-Elhaj, S

    2004-07-01

    Concentrations of heavy metals (Pb, Cd, Cu, Zn, Fe, Mn, Ni, and Cr) were investigated in roadside surface soil and the common perennial herb inula (Inula viscosa L., Compositae). Samples were collected at different distances (0-200 m) perpendicular to a main road that connects two main cities in the West Bank. Average concentrations of metals in soil samples were: Pb, 87.4; Cd, 0.27; Cu, 60.4; Zn, 82.2; Fe, 15,700; Mn, 224; Ni, 18.9; and Cr, 42.4 microg x g(-1). In plant leaves, concentrations were: Pb, 7.25; Cd, 0.10; Cu, 10.6; Zn, 47.6; Fe, 730; Mn, 140; Ni, 4.87; and Cr, 7.03 microg x g(-1). Roadside contamination was obvious by the significant negative correlations between concentrations of metals in soil and plant samples and distance from road edge. Only cadmium concentrations in soil and plant samples were not associated with roadside pollution. Roadside contamination in plants and soil did not extend much beyond a 20 m distance from road. I. viscosa reflected roadside contamination better than soil and their metal concentrations showed much less fluctuations than those in soil samples. Washing plant leaves decreased Pb and Fe concentrations significantly, indicating a significant aerial deposition of both. I. viscosa can be considered as a good biomonitor for roadside metal pollution.

  1. Controlling factors of surface soil moisture temporal stability at watershed scale

    Science.gov (United States)

    Wei, Lingna; Chen, Xi; Dong, Jianzhi; Gao, Man

    2016-04-01

    Soil moisture plays a significant role in the land surface-atmosphere interactions. Temporal stability was frequently used for estimating areal mean soil moisture using limited number of point measurements. This study investigated the factors that determine soil moisture temporal stability using simulated high spatial resolution soil moisture data at watershed scale. Results show locations under dominate vegetation cover and with low topographic wetness index (TI) values are likely to provide reasonable areal mean soil moisture estimates. We demonstrated that including the information of vegetation cover and TI can effectively reduce the number of the sampling locations that required for determining the representative point. The length of sampling period is also shown to be important in correctly determining the representative point. When 10 sampling points were used, a sampling period of approximately 300 days can provide robust areal mean soil moisture estimates of the entire study period of 9 years. The presented study may be useful for improving our skills in applying the temporal stability method for areal mean soil moisture estimating, and hence remote sensing product validation.

  2. Robust NdBa0.5Sr0.5Co1.5Fe0.5O5+δ cathode material and its degradation prevention operating logic for intermediate temperature-solid oxide fuel cells

    Science.gov (United States)

    Lee, Tae-Hee; Park, Ka-Young; Kim, Nam-In; Song, Sun-Ju; Hong, Ki-Ha; Ahn, Docheon; Azad, Abul K.; Hwang, Junyeon; Bhattacharjee, Satadeep; Lee, Seung-Cheol; Lim, Hyung-Tae; Park, Jun-Young

    2016-11-01

    We report solutions (durable material and degradation prevention method) to minimize the performance degradation of cell components occurring in the solid oxide fuel cell (SOFC) operation. Reliability testing is carried out with the Nisbnd Nd0.1Ce0.9O2-δ (NDC) anode-supported intermediate temperature-SOFCs. For the cathode materials, single perovskite structured Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and double perovskite structured NdBa0.5Sr0.5Co1.5Fe0.5O5+δ (NBSCF) are prepared and evaluated under harsh SOFC operating conditions. The double perovskite NBSCF cathode shows excellent stability in harsh SOFC environments of high humidity and low flow rate of air. Furthermore, we propose the concurrent fuel and air starvation mode, in which the cell potential is temporarily reduced due to the formation of both fuel-starvation (in the anode) and air-depletion (in the cathode) concurrently under a constant load. This is carried out in order to minimize the performance decay of the stable NBSCF-cell through the periodic and extra reduction of aH2 O (and aO2) in the anode. The operating-induced degradation of SOFCs, which are ordinarily assumed to be unrecoverable, can be completely circumvented by the proposed periodical operation logic to prevent performance degradation (concurrent fuel-starvation and air-depletion mode).

  3. Struchre and Electrical Properties of (Na0.5Bi0.5)0.94Ba0.06TiO3 Ceramic with 0.5 wt% of MnO

    Institute of Scientific and Technical Information of China (English)

    LIU Weihua; XU Qing; CHEN Wen; CHEN Min; KIM Bokhee

    2008-01-01

    The structure and electrical properties of(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramic doped with 0.5 wt% of MnO were investigated in comparison with those of(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramic.It was ascertained that the MnO addition did not cause remarkable change in crystal structure and microstructure.The MnO addition mainly displayed a hard effect on the electrical properties,an increase of coercive field(Ec)and mechanical quality factor(Qm)together with a decrease of dielectric constant(?r)and piezoelectric constant(d33).An enhancement of electromechanical coupling factor(kp)with the MnO addition was obtained too.An essential relation between the piezoelectric properties and ferroelectric nature of the ceramics was detected.It was found that the piezoelectric properties of the ceramics highly depended on the corporative contribution of remanent polarization(Pr)and coercive field.

  4. Using advanced surface complexation models for modelling soil chemistry under forests: Solling forest, Germany.

    Science.gov (United States)

    Bonten, Luc T C; Groenenberg, Jan E; Meesenburg, Henning; de Vries, Wim

    2011-10-01

    Various dynamic soil chemistry models have been developed to gain insight into impacts of atmospheric deposition of sulphur, nitrogen and other elements on soil and soil solution chemistry. Sorption parameters for anions and cations are generally calibrated for each site, which hampers extrapolation in space and time. On the other hand, recently developed surface complexation models (SCMs) have been successful in predicting ion sorption for static systems using generic parameter sets. This study reports the inclusion of an assemblage of these SCMs in the dynamic soil chemistry model SMARTml and applies this model to a spruce forest site in Solling Germany. Parameters for SCMs were taken from generic datasets and not calibrated. Nevertheless, modelling results for major elements matched observations well. Further, trace metals were included in the model, also using the existing framework of SCMs. The model predicted sorption for most trace elements well.

  5. Elevated soil CO2 efflux at the boundaries between impervious surfaces and urban greenspaces

    Science.gov (United States)

    Wu, XiaoGang; Hu, Dan; Ma, ShengLi; Zhang, Xia; Guo, Zhen; Gaston, Kevin J.

    2016-09-01

    Impervious surfaces and greenspaces have significant impacts on ecological processes and ecosystem services in urban areas. However, there have been no systematic studies of how the interaction between the two forms of land cover, and especially their edge effects, influence ecosystem properties. This has made it difficult to evaluate the effectiveness of urban greenspace design in meeting environmental goals. In this study, we investigated edge effects on soil carbon dioxide (CO2) fluxes in Beijing and found that soil CO2 flux rates were averagely 73% higher 10 cm inwards from the edge of greenspaces. Distance, soil temperature, moisture, and their interaction significantly influenced soil CO2 flux rates. The magnitude and distance of edge effects differed among impervious structure types. Current greening policy and design should be adjusted to avoid the carbon sequestration service of greenspaces being limited by their fragmentation.

  6. Phosphorus transport with runoff of simulated rainfall from purple-soil cropland of different surface conditions

    Institute of Scientific and Technical Information of China (English)

    GAO Yang; ZHANG Jin-zhong; ZHU Bo; ZHOU Pei; MIAO Chi-yuan; WANG Tao

    2008-01-01

    We investigated the patterns of phosphoru