WorldWideScience

Sample records for surface potential distribution

  1. Nuclear momentum distribution and potential energy surface in hexagonal ice

    Science.gov (United States)

    Lin, Lin; Morrone, Joseph; Car, Roberto; Parrinello, Michele

    2011-03-01

    The proton momentum distribution in ice Ih has been recently measured by deep inelastic neutron scattering and calculated from open path integral Car-Parrinello simulation. Here we report a detailed investigation of the relation between momentum distribution and potential energy surface based on both experiment and simulation results. The potential experienced by the proton is largely harmonic and characterized by 3 principal frequencies, which can be associated to weighted averages of phonon frequencies via lattice dynamics calculations. This approach also allows us to examine the importance of quantum effects on the dynamics of the oxygen nuclei close to the melting temperature. Finally we quantify the anharmonicity that is present in the potential acting on the protons. This work is supported by NSF and by DOE.

  2. Characterization of electrical conductivity of carbon fiber reinforced plastic using surface potential distribution

    Science.gov (United States)

    Kikunaga, Kazuya; Terasaki, Nao

    2018-04-01

    A new method of evaluating electrical conductivity in a structural material such as carbon fiber reinforced plastic (CFRP) using surface potential is proposed. After the CFRP was charged by corona discharge, the surface potential distribution was measured by scanning a vibrating linear array sensor along the object surface with a high spatial resolution over a short duration. A correlation between the weave pattern of the CFRP and the surface potential distribution was observed. This result indicates that it is possible to evaluate the electrical conductivity of a material comprising conducting and insulating regions.

  3. Electric Field and Potential Distributions along Surface of Silicone Rubber Polymer Insulators Using Finite Element Method

    OpenAIRE

    B. Marungsri; W. Onchantuek; A. Oonsivilai

    2008-01-01

    This paper presents the simulation the results of electric field and potential distributions along surface of silicone rubber polymer insulators. Near the same leakage distance subjected to 15 kV in 50 cycle salt fog ageing test, alternate sheds silicone rubber polymer insulator showed better contamination performance than straight sheds silicone rubber polymer insulator. Severe surface ageing was observed on the straight sheds insulator. The objective of this work is to ...

  4. Two-dimensional potential and charge distributions of positive surface streamer

    International Nuclear Information System (INIS)

    Tanaka, Daiki; Matsuoka, Shigeyasu; Kumada, Akiko; Hidaka, Kunihiko

    2009-01-01

    Information on the potential and the field profile along a surface discharge is required for quantitatively discussing and clarifying the propagation mechanism. The sensing technique with a Pockels crystal has been developed for directly measuring the potential and electric field distribution on a dielectric material. In this paper, the Pockels sensing system consists of a pulse laser and a CCD camera for measuring the instantaneous two-dimensional potential distribution on a 25.4 mm square area with a 50 μm sampling pitch. The temporal resolution is 3.2 ns which is determined by the pulse width of the laser emission. The transient change in the potential distribution of a positive surface streamer propagating in atmospheric air is measured with this system. The electric field and the charge distributions are also calculated from the measured potential profile. The propagating direction component of the electric field near the tip of the propagating streamer reaches 3 kV mm -1 . When the streamer stops, the potential distribution along a streamer forms an almost linear profile with the distance from the electrode, and its gradient is about 0.5 kV mm -1 .

  5. Surface potential measurement of negative-ion-implanted insulators by analysing secondary electron energy distribution

    International Nuclear Information System (INIS)

    Toyota, Yoshitaka; Tsuji, Hiroshi; Nagumo, Syoji; Gotoh, Yasuhito; Ishikawa, Junzo; Sakai, Shigeki.

    1994-01-01

    The negative ion implantation method we have proposed is a noble technique which can reduce surface charging of isolated electrodes by a large margin. In this paper, the way to specify the surface potential of negative-ion-implanted insulators by the secondary electron energy analysis is described. The secondary electron energy distribution is obtained by a retarding field type energy analyzer. The result shows that the surface potential of fused quartz by negative-ion implantation (C - with the energy of 10 keV to 40 keV) is negatively charged by only several volts. This surface potential is extremely low compared with that by positive-ion implantation. Therefore, the negative-ion implantation is a very effective method for charge-up free implantation without charge compensation. (author)

  6. Spatial distribution of potential near surface moisture flux at Yucca Mountain

    International Nuclear Information System (INIS)

    Flint, A.L.; Flint, L.E.

    1994-01-01

    An estimate of the areal distribution of present-day surface liquid moisture flux at Yucca Mountain was made using field measured water contents and laboratory measured rock properties. Using available data for physical and hydrologic properties (porosity, saturated hydraulic conductivity, moisture retention functions) of the volcanic rocks, surface lithologic units that are hydrologically similar were delineated. Moisture retention and relative permeability functions were assigned to each surface unit based on the similarity of the mean porosity and saturated hydraulic conductivity of the surface unit to laboratory samples of the same lithology. The potential flux into the mountain was estimated for each surface hydrologic unit using the mean saturated hydraulic conductivity for each unit and assuming all matrix flow. Using measured moisture profiles for each of the surface units, estimates were made of the depth at which seasonal fluctuations diminish and steady state downward flux conditions are likely to exist. The hydrologic properties at that depth were used with the current relative saturation of the tuff, to estimate flux as the unsaturated hydraulic conductivity. This method assumes a unit gradient. The range in estimated flux was 0.02 mm/yr for the welded Tiva Canyon to 13.4 mm/yr for the nonwelded Paintbrush Tuff. The areally averaged flux was 1.4 mm/yr. The major zones of high flux occur to the north of the potential repository boundary where the nonwelded tuffs are exposed in the major drainages

  7. Spatial distribution of potential near surface moisture flux at Yucca Mountain

    International Nuclear Information System (INIS)

    Flint, A.L.; Flint, L.E.

    1994-01-01

    An estimate of the areal distribution of present-day surface liquid moisture flux at Yucca Mountain was made using field measured water contents and laboratory measured rock properties. Using available data for physical and hydrologic properties (porosity, saturated hydraulic conductivity moisture retention functions) of the volcanic rocks, surface lithologic units that are hydrologically similar were delineated. Moisture retention and relative permeability functions were assigned to each surface unit based on the similarity of the mean porosity and saturated hydraulic conductivity of the surface unit to laboratory samples of the same lithology. The potential flux into the mountain was estimated for each surface hydrologic unit using the mean saturated hydraulic conductivity for each unit and assuming all matrix flow. Using measured moisture profiles for each of the surface units, estimates were made of the depth at which seasonal fluctuations diminish and steady state downward flux conditions are likely to exist. The hydrologic properties at that depth were used with the current relative saturation of the tuff, to estimate flux as the unsaturated hydraulic conductivity. This method assumes a unit gradient. The range in estimated flux was 0.02 mm/yr for the welded Tiva Canyon to 13.4 mm/yr for the nonwelded Paintbrush Tuff. The areally averaged flux was 1.4 mm/yr. The major zones of high flux occur to the north of the potential repository boundary where the nonwelded tuffs are exposed in the major drainages

  8. Determination of electrostatic potential distribution by atomic force microscopy (AFM) on model silica and alumina surfaces in aqueous electrolyte solutions

    International Nuclear Information System (INIS)

    Yelken, Gulnihal Ozek; Polat, Mehmet

    2014-01-01

    Graphical abstract: - Highlights: • Atomic force microscopy was employed to quantitatively determine the surface potential on silica and alumina surfaces immersed in aqueous electrolyte solutions at various pH values using the DLVO theory. • Potential distributions could be presented in the form of a potential map by repeating the procedure on multiple locations on these surfaces. • The average potential of the distributions agreed very well with the surface potentials measured by electrophoretic techniques. • Several experimental procedures required to achieve the very sensitive force measurements were outlined and demonstrated. - Abstract: AFM was employed as a physicochemical probe to determine the electrostatic potential distribution quantitatively on selected ideal oxide surfaces (quartz 0 0 0 1 and sapphire 0 0 0 1) in aqueous media. The force of interaction between a silicon nitride tip and the oxide surface was measured at a given point under well-defined solution conditions. Relevant theories were used to isolate the electrostatic component from the total force of interaction which was then employed to estimate the surface potential at that point. Repeating the procedure on selected locations generated a potential map of the surface. Comparison of these potentials with those obtained from independent electrokinetic measurements confirmed the validity of the approach

  9. Modified colloidal primitive model as a homogeneous surface charge distribution: ζ-potential.

    Science.gov (United States)

    Manzanilla-Granados, Héctor M; Lozada-Cassou, Marcelo

    2013-10-03

    An integral equations theory is derived and applied to a modified colloidal primitive model (MCPM), for finite concentration colloidal dispersions. In MCPM, the charge on the colloidal particle is assumed to be smeared on its surface. We find important quantitative and qualitative differences of the ζ-potential, induced charge, and the colloid-colloid electric effective force, calculated in the MCPM, with those obtained from the colloidal primitive model (CPM), where the colloidal charge is assumed to be in the center of the particle, in spite of the fact that, due to Gauss's law, both models have the same particle distribution function. In particular, for the same parameters, while the ζ-potential is positive in MCPM, is negative in the CPM, implying opposite electrophoretic mobilities, μ. An inverse μ has been theoretically predicted in the past, for infinite dilution colloidal dispersions. The MCPM could be a better model for some colloidal particles. In both models, the CPM and the MCPM, it is found a very long-range colloid-colloid correlation, in accordance with previous Monte Carlo simulations. The electrostatic, as well as entropic, like-charged colloid-colloid forces are oscillatory, implying a long-range attraction.

  10. Synoptic Sampling to Determine Distributed Groundwater-Surface Water Nitrate Loading and Removal Potential Along a Lowland River

    Science.gov (United States)

    Pai, Henry; Villamizar, Sandra R.; Harmon, Thomas C.

    2017-11-01

    Delineating pollutant reactive transport pathways that connect local land use patterns to surface water is an important goal. This work illustrates high-resolution river mapping of salinity or specific conductance (SC) and nitrate (NO3-) as a potential part of achieving this goal. We observed longitudinal river SC and nitrate distributions using high-resolution synoptic in situ sensing along the lower Merced River (38 river km) in Central California (USA) from 2010 to 2012. We calibrated a distributed groundwater-surface water (GW-SW) discharge model for a conservative solute using 13 synoptic SC sampling events at flows ranging from 1.3 to 31.6 m3 s-1. Nitrogen loads ranged from 0.3 to 1.6 kg N d-1 and were greater following an extended high flow period during a wet winter. Applying the distributed GW-SW discharge estimates to a simplistic reactive nitrate transport model, the model reproduced observed river nitrate distribution well (RRMSE = 5-21%), with dimensionless watershed-averaged nitrate removal (kt) ranging from 0 to 0.43. Estimates were uncertain due to GW nitrate data variability, but the resulting range was consistent with prior removal estimates. At the segment scale, estimated GW-SW nitrate loading ranged from 0 to 17 g NO3- s-1 km-1. Local loading peaked near the middle of the study reach, a location that coincides with a shallow clay lens and with confined animal feed operations in close proximity to the river. Overall, the results demonstrate the potential for high-resolution synoptic monitoring to support GW-SW modeling efforts aimed at understanding and managing nonpoint source pollution.

  11. Assessing spatial distribution, sources, and potential ecological risk of heavy metals in surface sediments of the Nansi Lake, Eastern China

    International Nuclear Information System (INIS)

    Jianshu Lv; Bin Dai; Zulu Zhang; Yuanyuan Sun; Shuang Li; Yang Liu

    2014-01-01

    The study is conducted to investigate the spatial distribution, sources and ecological risk of seven heavy metals in surface sediments of Nansi Lake, Eastern China. A total of 29 samples were collected in surface sediments of Nansi Lake, and were analyzed for three nutrients (TN, TOC and TP), two major metals (Al and Fe), as well as seven trace metals (As, Cd, Cr, Cu, Hg, Pb and Zn). The mean concentrations of As, Cd, Cr, Cu, Hg, Pb, Zn, Fe and Al were 14.41, 0.22, 71.10, 30.1, 0.048, 29.14, 90.2, 30,816 and 70,653 mg kg -1 , respectively, and the mean contents of these metals were higher than the background values with the exception of Cu and Fe. The spatial distribution indicated that the contents of all seven heavy metals were characterized by relatively higher contents in the upper lake than the lower lake. The hotspots with high values of As, Cd and Hg were associated with the river mouths, and the hotspots of Pb were mainly located around the dam in the central part, while no significant associations were displayed between spatial distribution of Cr, Cu, Zn and the river mouths. The mean enrichment factor (EF) values of As, Cd, Hg and Pb were 2.03, 2.93, 3.21 and 2.18, respectively, showing their moderate enrichment, while Cr, Cu and Zn with mean EF values of 1.19, 0.89 and 1.01 were deficiency to minimal enrichment. Multivariate and geostatistical analyses suggested that PC1 controlled by Cr, Cu and Zn was a lithogenic component, and come from parent rocks leaching. PC2 including Cd and partially Hg represented the factor from industrial wastewater discharge. PC3 showed elevated loadings of As and partially Cd, and could be attributed to the agricultural practices. While PC4 including Pb and partially Hg, was dominated by coal combustion. The results of potential ecological risk suggested that sediment environment of Nansi Lake suffered from high ecological risk. (author)

  12. The surface chemistry of divalent metal carbonate minerals; a critical assessment of surface charge and potential data using the charge distribution multi-site ion complexation model

    NARCIS (Netherlands)

    Wolthers, M.; Charlet, L.; Van Cappellen, P.

    2008-01-01

    The Charge Distribution MUltiSite Ion Complexation or CD–MUSIC modeling approach is used to describe the chemical structure of carbonate mineralaqueous solution interfaces. The new model extends existing surface complexation models of carbonate minerals, by including atomic scale information on

  13. Surface potential distribution and airflow performance of different air-exposed electrode plasma actuators at different alternating current/direct current voltages

    International Nuclear Information System (INIS)

    Yang, Liang; Yan, Hui-Jie; Qi, Xiao-Hua; Hua, Yue; Ren, Chun-Sheng

    2015-01-01

    Asymmetric surface dielectric barrier discharge (SDBD) plasma actuators have been intensely studied for a number of years due to their potential applications for aerodynamic control. In this paper, four types of actuators with different configurations of exposed electrode are proposed. The SDBD actuators investigated are driven by dual-power supply, referred to as a fixed AC high voltage and an adjustable DC bias. The effects of the electrode structures on the dielectric surface potential distribution, the electric wind velocity, and the mean thrust production are studied, and the dominative factors of airflow acceleration behavior are revealed. The results have shown that the actions of the SDBD actuator are mainly dependent on the geometry of the exposed electrode. Besides, the surface potential distribution can effectively affect the airflow acceleration behavior. With the application of an appropriate additional DC bias, the surface potential will be modified. As a result, the performance of the electric wind produced by a single SDBD can be significantly improved. In addition, the work also illustrates that the actuators with more negative surface potential present better mechanical performance

  14. Effect of SP-C on surface potential distribution in pulmonary surfactant: Atomic force microscopy and Kelvin probe force microscopy study

    International Nuclear Information System (INIS)

    Hane, Francis; Moores, Brad; Amrein, Matthias; Leonenko, Zoya

    2009-01-01

    The air-lung interface is covered by a molecular film of pulmonary surfactant (PS). The major function of the film is to reduce the surface tension of the lung's air-liquid interface, providing stability to the alveolar structure and reducing the work of breathing. Earlier we have shown that function of bovine lipid extract surfactant (BLES) is related to the specific molecular architecture of surfactant films. Defined molecular arrangement of the lipids and proteins of the surfactant film also give rise to a local highly variable electrical surface potential of the interface. In this work we investigated a simple model of artificial lung surfactant consisting of DPPC, eggPG, and surfactant protein C (SP-C). Effects of surface compression and the presence of SP-C on the monolayer structure and surface potential distribution were investigated using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We show that topography and locally variable surface potential of DPPC-eggPG lipid mixture are similar to those of pulmonary surfactant BLES in the presence of SP-C and differ in surface potential when SP-C is absent.

  15. [Age-related characteristics of the surface bioelectrical potential of human, canine and rat teeth and features of its distribution over the surface of the crown].

    Science.gov (United States)

    Donskiĭ, G I; Pavliuchenko, O N; Palamarchuk, Iu N; Makarova, N Ia

    1989-01-01

    Using a digital electron voltmeter, bioelectrical potentials (BEPs) of dental crowns have been recorded in 180 patients, 36 dogs, and 93 white non-inbred rats. It has been established that the surface BEP is a marker of dental enamel maturation and does not depend on the species of mammals. On the other hand maturation processes differ in their rate on the cutting edge, equator, and neck: with advancing age algebraic difference between the magnitudes of surface BEPs decreases in humans and increases in dogs and rats.

  16. Potential photosynthesis of crop surfaces.

    NARCIS (Netherlands)

    Wit, de C.T.

    1959-01-01

    A formula for calculating the potential photosynthesis of a closed crop surface is proposed, assuming that the leaves of the crop are not arranged in any definite direction. In the Netherlands, values for potential photosynthesis vary from 290 kg. CH2O/ha./day in June to 50 kg./ha./day in December.

  17. Shape estimation of the buried body from the ground surface potential distributions generated by current injection; Tsuryu ni yoru chihyomen den`i bunpu wo riyoshita maizobutsu keijo no suitei

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Y.; Okamoto, Y. [Chiba Institute of Technology, Chiba (Japan); Noguchi, K. [Waseda University, Tokyo (Japan); Teramachi, Y. [University of Industrial Technology, Kanagawa (Japan); Akabane, H.; Agu, M. [Ibaraki University, Ibaraki (Japan)

    1996-10-01

    Ground surface potential distribution generated by current injection was studied to estimate the shape of buried bodies. Since the uniform ground system including a homogeneous buried body is perfectly determined with the surface shape of a buried body and resistivities in/around a buried body, inversion is easy if the surface shape is described with some parameters. N electrodes are arranged in 2-D grid manner on the ground, and two electrodes among them are used for current injection, while the others for measurement of potentials. M times of measurements are repeated while changing combination of electrodes for current injection. The potential distribution measured by the mth electrode pair is represented by N-2 dimensional vectors. The square error between this distribution and calculated one is the function of k parameters on the surface shape and resistivities on a buried body. Both shape and resistivities can be estimated by solving an optimum value problem using the square error as evaluation function. Analysis is easy for a spherical body with 6 unknown parameters, however, it is difficult for more complex bodies than elliptical one or more than two bodies. 5 refs., 9 figs.

  18. On equilibrium charge distribution above dielectric surface

    Directory of Open Access Journals (Sweden)

    Yu.V. Slyusarenko

    2009-01-01

    Full Text Available The problem of the equilibrium state of the charged many-particle system above dielectric surface is formulated. We consider the case of the presence of the external attractive pressing field and the case of its absence. The equilibrium distributions of charges and the electric field, which is generated by these charges in the system in the case of ideally plane dielectric surface, are obtained. The solution of electrostatic equations of the system under consideration in case of small spatial heterogeneities caused by the dielectric surface, is also obtained. These spatial inhomogeneities can be caused both by the inhomogeneities of the surface and by the inhomogeneous charge distribution upon it. In particular, the case of the "wavy" spatially periodic surface is considered taking into account the possible presence of the surface charges.

  19. Potential energy surfaces for chemical reactions

    International Nuclear Information System (INIS)

    Schaefer, H.F. III.

    1976-01-01

    Research into potential energy surfaces for chemical reactions at Lawrence Berkeley Laboratory during 1976 is described. Topics covered include: the fuzzy interface between surface chemistry catalysis and organometallic chemistry; potential energy surfaces for elementary fluorine hydrogen reactions; structure, energetics, and reactivity of carbenes; and the theory of self-consistent electron pairs

  20. Galaxy Selection and the Surface Brightness Distribution

    Science.gov (United States)

    McGaugh, Stacy S.; Bothun, Gregory D.; Schombert, James M.

    1995-08-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney [Nature, 263,573(1976)] suggested that the constancy of disk central surface brightness noticed by Freeman [ApJ, 160,811(1970)] was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (i.e., approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity function at L^*^. An intrinsically sharply peaked "Freeman law" distribution can be completely ruled out, and no Gaussian distribution can fit the data. Low surface brightness galaxies (those with central surface brightness fainter than 22 B mag arcsec^-2^) comprise >~ 1/2 the general galaxy population, so a representative sample of galaxies at z = 0 does not really exist at present since past surveys have been insensitive to this component of the general galaxy population.

  1. Application of Analytical Model of the Electric Potential Distribution for Calculation of Charged Particle Dynamics in a Near-Wall Layer and Sputtering of the Plasma Facing Surfaces

    Czech Academy of Sciences Publication Activity Database

    Borodkina, I.E.; Komm, Michael; Tsvetkov, I.V.

    2015-01-01

    Roč. 58, č. 4 (2015), s. 438-445 ISSN 1064-8887 Institutional support: RVO:61389021 Keywords : plasma-surface interaction * magnetic pre-layer * Debye layer * inclined magnetic field * sputtering Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.667, year: 2015 http://link.springer.com/article/10.1007%2Fs11182-015-0518-5

  2. Scanning Surface Potential Microscopy of Spore Adhesion on Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ida [University of Tennessee, Knoxville (UTK); Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

    2012-01-01

    The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica.

  3. Scanning surface potential microscopy of spore adhesion on surfaces.

    Science.gov (United States)

    Lee, I; Chung, E; Kweon, H; Yiacoumi, S; Tsouris, C

    2012-04-01

    The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Atom-surface potentials and atom interferometry

    International Nuclear Information System (INIS)

    Babb, J.F.

    1998-01-01

    Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

  5. A Variance Distribution Model of Surface EMG Signals Based on Inverse Gamma Distribution.

    Science.gov (United States)

    Hayashi, Hideaki; Furui, Akira; Kurita, Yuichi; Tsuji, Toshio

    2017-11-01

    Objective: This paper describes the formulation of a surface electromyogram (EMG) model capable of representing the variance distribution of EMG signals. Methods: In the model, EMG signals are handled based on a Gaussian white noise process with a mean of zero for each variance value. EMG signal variance is taken as a random variable that follows inverse gamma distribution, allowing the representation of noise superimposed onto this variance. Variance distribution estimation based on marginal likelihood maximization is also outlined in this paper. The procedure can be approximated using rectified and smoothed EMG signals, thereby allowing the determination of distribution parameters in real time at low computational cost. Results: A simulation experiment was performed to evaluate the accuracy of distribution estimation using artificially generated EMG signals, with results demonstrating that the proposed model's accuracy is higher than that of maximum-likelihood-based estimation. Analysis of variance distribution using real EMG data also suggested a relationship between variance distribution and signal-dependent noise. Conclusion: The study reported here was conducted to examine the performance of a proposed surface EMG model capable of representing variance distribution and a related distribution parameter estimation method. Experiments using artificial and real EMG data demonstrated the validity of the model. Significance: Variance distribution estimated using the proposed model exhibits potential in the estimation of muscle force. Objective: This paper describes the formulation of a surface electromyogram (EMG) model capable of representing the variance distribution of EMG signals. Methods: In the model, EMG signals are handled based on a Gaussian white noise process with a mean of zero for each variance value. EMG signal variance is taken as a random variable that follows inverse gamma distribution, allowing the representation of noise superimposed onto this

  6. Computed potential energy surfaces for chemical reactions

    Science.gov (United States)

    Walch, Stephen P.; Levin, Eugene

    1993-01-01

    A new global potential energy surface (PES) is being generated for O(P-3) + H2 yields OH + H. This surface is being fit using the rotated Morse oscillator method, which was used to fit the previous POL-CI surface. The new surface is expected to be more accurate and also includes a much more complete sampling of bent geometries. A new study has been undertaken of the reaction N + O2 yields NO + O. The new studies have focused on the region of the surface near a possible minimum corresponding to the peroxy form of NOO. A large portion of the PES for this second reaction has been mapped out. Since state to state cross sections for the reaction are important in the chemistry of high temperature air, these studies will probably be extended to permit generation of a new global potential for reaction.

  7. Spot distribution and fast surface evolution on Vega

    Science.gov (United States)

    Petit, P.; Hébrard, E. M.; Böhm, T.; Folsom, C. P.; Lignières, F.

    2017-11-01

    Spectral signatures of surface spots were recently discovered from high cadence observations of the A star Vega. We aim at constraining the surface distribution of these photospheric inhomogeneities and investigating a possible short-term evolution of the spot pattern. Using data collected over five consecutive nights, we employ the Doppler imaging method to reconstruct three different maps of the stellar surface, from three consecutive subsets of the whole time series. The surface maps display a complex distribution of dark and bright spots, covering most of the visible fraction of the stellar surface. A number of surface features are consistently recovered in all three maps, but other features seem to evolve over the time span of observations, suggesting that fast changes can affect the surface of Vega within a few days at most. The short-term evolution is observed as emergence or disappearance of individual spots, and may also show up as zonal flows, with low- and high-latitude belts rotating faster than intermediate latitudes. It is tempting to relate the surface brightness activity to the complex magnetic field topology previously reconstructed for Vega, although strictly simultaneous brightness and magnetic maps will be necessary to assess this potential link.

  8. Incorporating Skew into RMS Surface Roughness Probability Distribution

    Science.gov (United States)

    Stahl, Mark T.; Stahl, H. Philip.

    2013-01-01

    The standard treatment of RMS surface roughness data is the application of a Gaussian probability distribution. This handling of surface roughness ignores the skew present in the surface and overestimates the most probable RMS of the surface, the mode. Using experimental data we confirm the Gaussian distribution overestimates the mode and application of an asymmetric distribution provides a better fit. Implementing the proposed asymmetric distribution into the optical manufacturing process would reduce the polishing time required to meet surface roughness specifications.

  9. Potential energy surface of alanine polypeptide chains

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Yakubovich, Alexander V.; Solov'yov, Andrey V.

    2006-01-01

    The multidimensional potential energy surfaces of the peptide chains consisting of three and six alanine (Ala) residues have been studied with respect to the degrees of freedom related to the twist of these molecules relative to the peptide backbone (these degrees of freedom are responsible...

  10. Urban Surfaces and Heat Island Mitigation Potentials

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, Hashem; Akbari, Hashem; Shea Rose, Leanna

    2007-06-14

    Data on materials and surface types that comprise a city, i.e. urban fabric, are needed in order to estimate the effects of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city. We discuss the results of a semi-automatic statistical approach used to develop data on surface-type distribution and urban-fabric makeup using aerial color orthophotography, for four metropolitan areas of Chicago, IL, Houston, TX, Sacramento, CA, and Salt Lake City, UT. The digital high resolution (0.3 to 0.5-m) aerial photographs for each of these metropolitan areas covers representative urban areas ranging from 30 km{sup 2} to 52 km{sup 2}. Major land-use types examined included: commercial, residential, industrial, educational, and transportation. On average, for the metropolitan areas studied, vegetation covers about 29-41% of the area, roofs 19-25%, and paved surfaces 29-39%. For the most part, trees shade streets, parking lots, grass, and sidewalks. At ground level, i.e., view from below the tree canopies, vegetation covers about 20-37% of the area, roofs 20-25%, and paved surfaces 29-36%.

  11. Computed potential energy surfaces for chemical reactions

    Science.gov (United States)

    Walch, Stephen P.

    1994-01-01

    Quantum mechanical methods have been used to compute potential energy surfaces for chemical reactions. The reactions studied were among those believed to be important to the NASP and HSR programs and included the recombination of two H atoms with several different third bodies; the reactions in the thermal Zeldovich mechanism; the reactions of H atom with O2, N2, and NO; reactions involved in the thermal De-NO(x) process; and the reaction of CH(squared Pi) with N2 (leading to 'prompt NO'). These potential energy surfaces have been used to compute reaction rate constants and rates of unimolecular decomposition. An additional application was the calculation of transport properties of gases using a semiclassical approximation (and in the case of interactions involving hydrogen inclusion of quantum mechanical effects).

  12. Potential energy surface of triplet O4.

    Science.gov (United States)

    Paukku, Yuliya; Varga, Zoltan; Truhlar, Donald G

    2018-03-28

    We present a global ground-state potential energy surface (PES) for the triplet spin state of O 4 that is suitable for treating high-energy vibrational-rotational energy transfer and collision-induced dissociation in electronically adiabatic spin-conserving O 2 -O 2 collisions. The surface is based on MS-CASPT2/maug-cc-pVTZ electronic structure calculations with scaled external correlation; the active space has 16 electrons in 12 orbitals. The global ground-state potential energy surface was fitted by a many-body approach with an accurate O-O pairwise interaction and a fit of the many-body interaction potential to 10 180 electronic structure data points. The many-body fit is based on permutationally invariant polynomials in terms of bond-order functions of the six interatomic distances; the bond-order functions are mixed exponential-Gaussian functions. The geometries calculated and used for the fit include geometry scans corresponding to dissociative and vibrationally excited diatom-diatom collisions of O 2 , scans corresponding to O 3 interacting with O, additional geometries identified by running trajectories, and geometries along linear synchronous transit paths connecting randomly selected points. The global O 4 PES includes subsurfaces describing the interaction of diatomic molecules with other diatomic molecules or interactions of triatomic molecules and an atom. The interaction of ozone with a ground-state oxygen atom occurs on the triplet O 4 surface, and our surface includes high-energy points with O 3 -O geometries as well as O 2 -O 2 geometries and O 2 -O-O geometries.

  13. Theoretical studies of potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Harding, L.B. [Argonne National Laboratory, IL (United States)

    1993-12-01

    The goal of this program is to calculate accurate potential energy surfaces (PES) for both reactive and nonreactive systems. To do this the electronic Schrodinger equation must be solved. Our approach to this problem starts with multiconfiguration self-consistent field (MCSCF) reference wavefunctions. These reference wavefunctions are designed to be sufficiently flexible to accurately describe changes in electronic structure over a broad range of geometries. Electron correlation effects are included via multireference, singles and doubles configuration interaction (MRSDCI) calculations. With this approach, the authors are able to provide useful predictions of the energetics for a broad range of systems.

  14. Convergent surface water distributions in U.S. cities

    Science.gov (United States)

    M.K. Steele; J.B. Heffernan; N. Bettez; J. Cavender-Bares; P.M. Groffman; J.M. Grove; S. Hall; S.E. Hobbie; K. Larson; J.L. Morse; C. Neill; K.C. Nelson; J. O' Neil-Dunne; L. Ogden; D.E. Pataki; C. Polsky; R. Roy Chowdhury

    2014-01-01

    Earth's surface is rapidly urbanizing, resulting in dramatic changes in the abundance, distribution and character of surface water features in urban landscapes. However, the scope and consequences of surface water redistribution at broad spatial scales are not well understood. We hypothesized that urbanization would lead to convergent surface water abundance and...

  15. Energy conservation potential of surface modification technologies

    Energy Technology Data Exchange (ETDEWEB)

    Le, H.K.; Horne, D.M.; Silberglitt, R.S.

    1985-09-01

    This report assesses the energy conservation impact of surface modification technologies on the metalworking industries. The energy conservation impact of surface modification technologies on the metalworking industries is assessed by estimating their friction and wear tribological sinks and the subsequent reduction in these sinks when surface modified tools are used. Ion implantation, coatings, and laser and electron beam surface modifications are considered.

  16. Computed potential energy surfaces for chemical reactions

    Science.gov (United States)

    Walch, Stephen P.

    1988-01-01

    The minimum energy path for the addition of a hydrogen atom to N2 is characterized in CASSCF/CCI calculations using the (4s3p2d1f/3s2p1d) basis set, with additional single point calculations at the stationary points of the potential energy surface using the (5s4p3d2f/4s3p2d) basis set. These calculations represent the most extensive set of ab initio calculations completed to date, yielding a zero point corrected barrier for HN2 dissociation of approx. 8.5 kcal mol/1. The lifetime of the HN2 species is estimated from the calculated geometries and energetics using both conventional Transition State Theory and a method which utilizes an Eckart barrier to compute one dimensional quantum mechanical tunneling effects. It is concluded that the lifetime of the HN2 species is very short, greatly limiting its role in both termolecular recombination reactions and combustion processes.

  17. Surface Area Distribution Descriptor for object matching

    Directory of Open Access Journals (Sweden)

    Mohamed F. Gafar

    2010-07-01

    Full Text Available Matching 3D objects by their similarity is a fundamental problem in computer vision, computer graphics and many other fields. The main challenge in object matching is to find a suitable shape representation that can be used to accurately and quickly discriminate between similar and dissimilar shapes. In this paper we present a new volumetric descriptor to represent 3D objects. The proposed descriptor is used to match objects under rigid transformations including uniform scaling. The descriptor represents the object by dividing it into shells, acquiring the area distribution of the object through those shells. The computed areas are normalised to make the descriptor scale-invariant in addition to rotation and translation invariant. The effectiveness and stability of the proposed descriptor to noise and variant sampling density as well as the effectiveness of the similarity measures are analysed and demonstrated through experimental results.

  18. An Ab Initio Based Potential Energy Surface for Water

    Science.gov (United States)

    Partridge, Harry; Schwenke, David W.; Langhoff, Stephen R. (Technical Monitor)

    1996-01-01

    We report a new determination of the water potential energy surface. A high quality ab initio potential energy surface (PES) and dipole moment function of water have been computed. This PES is empirically adjusted to improve the agreement between the computed line positions and those from the HITRAN 92 data base. The adjustment is small, nonetheless including an estimate of core (oxygen 1s) electron correlation greatly improves the agreement with experiment. Of the 27,245 assigned transitions in the HITRAN 92 data base for H2(O-16), the overall root mean square (rms) deviation between the computed and observed line positions is 0.125/cm. However the deviations do not correspond to a normal distribution: 69% of the lines have errors less than 0.05/cm. Overall, the agreement between the line intensities computed in the present work and those contained in the data base is quite good, however there are a significant number of line strengths which differ greatly.

  19. Frequency response in surface-potential driven electrohydrodynamics

    DEFF Research Database (Denmark)

    Ejsing, Louise Wellendorph; Smistrup, Kristian; Pedersen, Christian Møller

    2006-01-01

    capacitance where the net flow rate is, in general, zero while harmonic rolls as well as time-averaged vortexlike components may exist depending on the spatial symmetry and extension of the surface potential. In general, the system displays a resonance behavior at a frequency corresponding to the inverse RC...... time of the system. Different surface potentials share the common feature that the resonance frequency is inversely proportional to the characteristic length scale of the surface potential. For the asymptotic frequency dependence above resonance we find a omega(-2) power law for surface potentials...

  20. Doubly localized surface plasmon resonance in bimodally distributed silver nanoparticles.

    Science.gov (United States)

    Ranjan, M

    2012-06-01

    Growth of bimodally distributed silver nanoparticles using sequential physical vapour deposition (PVD) is reported. Growth conditions of nanoparticles are defined in the following three steps: In the first step, nanoparticles are grown at a heated substrate and then exposed to atmosphere, in the second step, nanoparticles are vacuum annealed and finally re-deposition of silver is performed in the third step. This special way of deposition leads to the formation of bimodally distributed nanoparticles. It has been investigated that by changing the deposition time, different sets of bimodally distributed nanoparticles can be grown. Localized surface plasmon resonance (LSPR) of such bimodally distributed nanoparticles generates double plasmon resonance peaks with overlapped absorption spectra. Double plasmon resonance peaks provide a quick indication of the existence of two sets of nanoparticles. LSPR spectra of such bimodally distributed nanoparticles could be modeled with double Lorentz oscillator model. Inclusion of double Lorentz oscillator model indicates that there exist two sets of non-interacting nanoparticles resonating at different plasma frequencies. It is also reported that silver nanoparticles grown at a heated substrate, again attain the new shape while being exposed to atmosphere, followed by vacuum annealing at the same temperature. This is because of physisorption of oxygen at the silver surface and change in surface free energy. The re-shaping due to the adsorbed oxygen on the surface is responsible for bimodal size distribution of nanoparticles.

  1. Bernoulli potential at a superconductor surface

    Czech Academy of Sciences Publication Activity Database

    Lipavský, Pavel; Koláček, Jan; Mareš, Jiří J.; Morawetz, K.

    2001-01-01

    Roč. 65, - (2001), s. 012507-1-012507-3 ISSN 0163-1829 R&D Projects: GA ČR GA202/00/0643; GA ČR GA202/99/0410; GA AV ČR IAA1010806; GA AV ČR IAA1010919 Institutional research plan: CEZ:AV0Z1010914 Keywords : Hall effect * Bernoulli potential Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.070, year: 2001

  2. Distribution of asset price movement and market potential

    Science.gov (United States)

    Kim, Dong Han; Marmi, Stefano

    2015-07-01

    In this article we discuss the distribution of asset price movements by introducing a market potential function. From the principle of free energy minimization we analyze two different kinds of market potentials. We obtain a U-shaped potential when market reversion (i.e. contrarian investors) is dominant. On the other hand, if there are more trend followers, flat and logarithmic potentials appear. By using the cyclically adjusted price-to-earning ratio, which is a common valuation tool, we empirically investigate the market data. By studying long term data we observe the historical change of the market potential of the US stock market. Recent US data show that the market potential looks more like a trend-following potential. Next, we compare the market potentials for 12 different countries. Though some countries have similar market potentials, there are specific examples like Japan which exhibits a very flat potential.

  3. Spatial distribution of potential and positive Aedes aegypti breeding sites

    Directory of Open Access Journals (Sweden)

    Daniel Elías Cuartas

    2017-03-01

    Conclusions: The spatial relationship between positive and potential A. aegypti breeding sites both indoors and outdoors is dynamic and highly sensitive to the characteristics of each territory. Knowing how positive and potential breeding sites are distributed contributes to the prioritization of resources and actions in vector control programs.

  4. Distribution of potential nosocomial pathogens in a hospital ...

    African Journals Online (AJOL)

    Distribution of potential nosocomial pathogens in a hospital environment. ... length of service were significant determining factors for the carriage rate of the isolates in the individuals examined. The findings of the study showed that the hospital may be a potential reservoir of organisms likely to cause nosocomial infections.

  5. The electric potential of the lunar surface

    Science.gov (United States)

    Fenner, M. A.; Freeman, J. W., Jr.; Hills, H. K.

    1973-01-01

    Acceleration and detection of the lunar thermal ionosphere in the presence of the lunar electric field yields a value of at least +10 V for the lunar electric potential for solar zenith angles between approximately 20 and 45 deg and in the magnetosheath or solar wind. An enhanced positive ion flux is observed with the ALSEP Suprathermal Ion Detector when a pre-acceleration voltage attains certain values. This enhancement is greater when the moon is in the solar wind as opposed to the magnetosheath.

  6. Lunar electric fields, surface potential and associated plasma sheaths

    Science.gov (United States)

    Freeman, J. W.; Ibrahim, M.

    1975-01-01

    A review is given of studies of the electric-field environment of the moon. Surface electric potentials are reported for the dayside and terminator regions, electron and ion densities in the plasma sheath adjacent to each surface-potential regime are evaluated, and the corresponding Debye lengths are estimated. The electric fields, which are approximated by the surface potential over the Debye length, are shown to be at least three orders of magnitude higher than the pervasive solar-wind electric field and to be confined to within a few tens of meters of the lunar surface.

  7. Green's functions potential fields on surfaces

    CERN Document Server

    Melnikov, Yuri A

    2017-01-01

    This book is comprehensive in its classical mathematical physics presentation, providing the reader with detailed instructions for obtaining Green's functions from scratch. Green's functions is an instrument easily accessible to practitioners who are engaged in design and exploitation of machines and structures in modern engineering practice. To date, there are no books available on the market that are devoted to the Green's function formalism for equations covered in this volume. The reader, with an undergraduate background in applied mathematics, can become an active user of the Green's function approach. For the first time, Green's functions are discussed for a specific class of problems dealing with potential fields induced in thin-wall structures and therefore, the reader will have first-hand access to a novel issue. This Work is accessible to researchers in applied mathematics, mechanics, and relevant disciplines such as engineering, as well as to upper level undergraduates and graduate students.

  8. Surface Potential of Polycrystalline Hematite in Aqueous Medium

    Directory of Open Access Journals (Sweden)

    Tajana Preočanin

    2011-01-01

    Full Text Available The surface potential of polycrystalline hematite in aqueous sodium perchlorate environment as a function of pH was examined. Surface potential of hematite was obtained from measured electrode potential of a nonporous polycrystalline hematite electrode. Acidic solution was titrated with base, and the backward titration with acid was performed. Substantial hysteresis was obtained which enabled location of the point of zero potential and equilibrium values of surface potentials. The theoretical interpretation of the equilibrium data was performed by applying the surface complexation model and the thermodynamic equilibrium constants for the first and the second step of surface protonation was obtained as logK1∘=11.3;logK2∘=2.8.

  9. Surface potential modeling and reconstruction in Kelvin probe force microscopy.

    Science.gov (United States)

    Xu, Jie; Wu, Yangqing; Li, Wei; Xu, Jun

    2017-09-08

    Kelvin probe force microscopy (KPFM) measurement has been extensively applied in metallic, semiconductor and organic electronic or photovoltaic devices, to characterize the local contact potential difference or surface potential of the samples at the nanoscale. Here, a comprehensive modeling of surface potential in KPFM is established, from the well-known single capacitance model to a precise electrodynamic model, considering the long range property of the electrostatic force in KPFM. The limitations and relations of different models are also discussed. Besides, the feedback condition of the KPFM system is reconsidered and modified, showing that the influence of the cantilever has been overestimated by about 20% in previous reports. Afterwards, the surface potential of charged Si-nanocrystals is reconstructed based on the electrodynamic model, and the calculated surface charge density is very consistent with the macroscopic capacitance-voltage (C-V) measurement. A deep understanding and correct reconstruction of surface potential is crucial to the quantitative analysis of KPFM results.

  10. Cardiac Body Surface Potentials in Rats with Experimental Pulmonary Hypertension during Ventricular Depolarization.

    Science.gov (United States)

    Suslonova, O V; Smirnova, S L; Roshchevskaya, I M

    2016-11-01

    The spatial and the amplitude-temporal parameters of cardiac body surface potentials were examined in female Wistar rats with experimental pulmonary hypertension during ventricular depolarization. The cardiac body surface potentials have been led from 64 subcutaneous electrodes evenly distributed across the chest surface prior to and 4 weeks after subcutaneous injection of a single dose of monocrotaline (60 mg/kg). Right ventricular hypertrophy and electrophysiological remodeling of the heart developed in rats with experimental pulmonary hypertension in 4 weeks after monocrotaline injection; these changes led to a significant increase in amplitude and temporal characteristics of the cardioelectric field on the body surface in comparison with the initial state.

  11. Pesticides distribution in surface waters and sediments of lotic and ...

    African Journals Online (AJOL)

    An investigation on the availability and distribution of Lindane (HCHs) and Total organochlorine phosphate (TOCP) in the surface waters and sediments of selected water bodies in Agbede wetlands was carried out from December, 2012 to May, 2014 in order to cover seasonal trends in both matrixes. A Gas Chromatograph ...

  12. Surface water assessment on the influence of space distribution on ...

    African Journals Online (AJOL)

    In this work, the influence of space distribution on physico-chemical parameters of refinery effluent discharge has been studied, using treated effluent water discharged from the Port Harcourt Refinery Company (PHRC) into the Ekerekana Creek in Okrika as reference. Samples were collected at surface level from the ...

  13. Near Surface Seismic Reflection Imaging: Great Potential Under Critical Eye

    Science.gov (United States)

    Miller, R. D.; Peterie, S.; Judy, B. E.

    2014-12-01

    Seismic-reflection imaging has long been a mainstay in the oil and gas exploration community with mind boggling advancements in just the last decade, but its application to engineering, environmental, and groundwater problems has not seen the same level of utilization. A great deal of the problem lies in the many assumptions that are valid for deep exploration that are violated in the very complex near surface. Large channel systems with acquisition geometries conducive for both deep and shallow targets are many times assumed to be capable of extending the imaging depth window. In reality, constraints of the source and sensor/recording systems must be considered, where large powerful sources are needed to image exploration depths while low-energy, high-frequency sources are required for the shallow and thin targets in the near surface. Attempts to make one size fit all will result in artifacts that result in bogus images and characterizations in the shallow subsurface.Narrow optimum offsets, highly attenuative materials, extreme velocity variability, wavefield interference, and low signal-to-noise ratios provide an ideal breeding ground for the generation of artifacts on near-surface seismic-reflection data. With the cost of shallow reflection data being so high relative to other geophysical methods and invasive sampling, sometimes a single failure can hinder the growth in the use of the method. The method is extremely powerful and has the potential to provide vast quantities of information critical to understand the distributed hydrogeological and biogeochemical processes that elude borehole investigations. It is imperative that data be acquired in its rawest possible form and be processed with an eye to each operation. Cost savings sometimes result in one-size-fits-all acquisition and automated processing flows. Attention to detail and following signal from origination to characterization is essential.

  14. The mapping of the measured cardiac electric potential and magnetic-field distribution

    NARCIS (Netherlands)

    Peters, M.J.; Dunajski, Z.; Heringa, A.; van Dam, R.Th.

    1983-01-01

    The distribution of both the cardiac electric potential on the body surface and the cardiac magnetic field near the chest and back is recorded at fixed time instants of the heart cycle. The general features of both types of maps are simple and reproducible, moreover they both reveal different

  15. A many-body embedded atom potential for describing ejection of atoms from surfaces

    International Nuclear Information System (INIS)

    Garrison, B.J.; Walzl, K.; El-Maazawi, M.; Winograd, N.; Reimann, C.T.; Deaven, D.M.

    1989-01-01

    In this paper, we show that many-body interactions are important for describing the energy- and angle-resolved distributions of neutral Rh atoms ejected from keV-ion-bombarded Rh{111}. We compare separate classical-dynamics simulations of the sputtering process assuming either a many-body potential or a pairwise additive potential. The most dramatic difference between the many-body potential and the pair potential is the predicted kinetic energy distributions. The pair-potential kinetic energy distribution peaks at ∼ 2 eV, whereas the many-body potential predicts a broader peak at ∼ 4 eV, giving much better agreement with experiment. This difference between the model potentials is due to the predicted nature of the attractive interaction in the surface region through which all ejecting particles pass. (author)

  16. Effects of flexoelectricity and surface elasticity on piezoelectric potential in a bent ZnO nanowire

    Science.gov (United States)

    Zhang, Shuangzhe; Yao, Haiyan; Fan, Wenliang; Hao, Yu; Wu, Xudong; Hou, Dongyuan

    2017-01-01

    In this work, a rapid model is established to study the effects of flexoelectricity and surface elasticity on the piezoelectric potential of a bent ZnO nanowire. Based on the piezoelectric theory and core-surface model, the distribution of piezoelectric potential of the ZnO nanowire is investigated. The analytical solution shows that the flexoelectricity and surface elasticity both significantly influence the piezoelectric potential. However, the effect of flexoelectricity is longitudinal dependent, which vanishes on the top side of nanowire, but only left surface elasticity effect on the potential. Simulation results show that the maximum value of potential on the top side of nanowire is about ± 220.5mV, of which result is lower compared to other theoretical models, but it should be more reasonable.

  17. Potential, Distribution, Ethno-Botany and Tapping Procedures of ...

    African Journals Online (AJOL)

    Potential, Distribution, Ethno-Botany and Tapping Procedures of Gum Producing Acacia Species in the Somali Region, Southeastern Ethiopia. ... Therefore, promotion of gum extraction in the Somali Region both for economic benefit of the community and sustainable management of the fragile ecosystem is recommended.

  18. Distribution of genes associated with yield potential and water ...

    Indian Academy of Sciences (India)

    Supplementary data: Distribution of genes associated with yield potential and water-saving in. Chinese Zone II wheat detected by developed functional markers. Zhenxian Gao, Zhanliang Shi, Aimin Zhang and Jinkao Guo. J. Genet. 94, 35–42. Table 1. Functional markers for high-yield or water-saving genes in wheat and ...

  19. Distribution of potential nosocomial pathogens in a hospital ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-10-20

    Oct 20, 2008 ... Full Length Research Paper. Distribution of potential nosocomial pathogens in a hospital environment. C. B. Chikere1*, V. T. Omoni1 and B. O. Chikere2. 1Department of Microbiology, University of Port Harcourt, P. M. B. 5323, Port Harcourt, Rivers State, Nigeria. 2Department of Microbiology, Federal ...

  20. Representing Global Reactive Potential Energy Surfaces Using Gaussian Processes.

    Science.gov (United States)

    Kolb, Brian; Marshall, Paul; Zhao, Bin; Jiang, Bin; Guo, Hua

    2017-04-06

    Representation of multidimensional global potential energy surfaces suitable for spectral and dynamical calculations from high-level ab initio calculations remains a challenge. Here, we present a detailed study on constructing potential energy surfaces using a machine learning method, namely, Gaussian process regression. Tests for the 3 A″ state of SH 2 , which facilitates the SH + H ↔ S( 3 P) + H 2 abstraction reaction and the SH + H' ↔ SH' + H exchange reaction, suggest that the Gaussian process is capable of providing a reasonable potential energy surface with a small number (∼1 × 10 2 ) of ab initio points, but it needs substantially more points (∼1 × 10 3 ) to converge reaction probabilities. The implications of these observations for construction of potential energy surfaces are discussed.

  1. Ab initio adiabatic and quasidiabatic potential energy surfaces of H ...

    Indian Academy of Sciences (India)

    s12039-015-1022-8. Ab initio adiabatic and quasidiabatic potential energy surfaces of H. ++. CN system. BHARGAVA ANUSURI and SANJAY KUMAR. ∗. Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India.

  2. Surface motion and confinement potential for a microwave confined corona

    International Nuclear Information System (INIS)

    Ensley, D.L.

    1979-07-01

    Approximate time dependent solutions for surface velocities and potentials are given for a plane polarized microwave field confining a hot, over-dense plasma corona. Steady state solutions to Poissons' equation can be applied to the time dependent case, provided transit time effects are included. The product of ion pressure and potential wave (surface) velocity gives an average heating rate approx. 7/32 NKT 0 V/sub theta/ directly to the ions

  3. Optimization of an Aeroservoelastic Wing with Distributed Multiple Control Surfaces

    Science.gov (United States)

    Stanford, Bret K.

    2015-01-01

    This paper considers the aeroelastic optimization of a subsonic transport wingbox under a variety of static and dynamic aeroelastic constraints. Three types of design variables are utilized: structural variables (skin thickness, stiffener details), the quasi-steady deflection scheduling of a series of control surfaces distributed along the trailing edge for maneuver load alleviation and trim attainment, and the design details of an LQR controller, which commands oscillatory hinge moments into those same control surfaces. Optimization problems are solved where a closed loop flutter constraint is forced to satisfy the required flight margin, and mass reduction benefits are realized by relaxing the open loop flutter requirements.

  4. Collisionless Plasma Modeling in an Arbitrary Potential Energy Distribution

    Science.gov (United States)

    Liemohn, M. W.; Khazanov, G. V.

    1997-01-01

    A new technique for calculating a collisionless plasma along a field line is presented. The primary feature of the new model is that it can handle an arbitrary (including nonmonotonic) potential energy distribution. This was one of the limiting constraints on the existing models in this class, and these constraints are generalized for an arbitrary potential energy composition. The formulation for relating current density to the field-aligned potential as well as formulas for density, temperature and energy flux calculations are presented for several distribution functions, ranging from a bi-Lorentzian with a loss cone to an isotropic Maxwellian. A comparison of these results with previous models shows that the formulation reduces.to the earlier models under similar assumptions.

  5. Potential energy surface for ? dissociation including spin-orbit effects

    Science.gov (United States)

    Siebert, Matthew R.; Aquino, Adelia J. A.; de Jong, Wibe A.; Granucci, Giovanni; Hase, William L.

    2012-10-01

    Previous experiments [J. Phys. Chem. A 116, 2833 (2012)] have studied the dissociation of 1,2-diiodoethane radical cation ( ? ) and found a one-dimensional distribution of translational energy, an odd finding considering most product relative translational energy distributions are two-dimensional. The goal of this study is to obtain an accurate understanding of the potential energy surface (PES) topology for the unimolecular decomposition reaction ? → C2H4I+ + I•. This is done through comparison of many single-reference electronic structure methods, coupled-cluster single-point (energy) calculations, and multi-reference energy calculations used to quantify spin-orbit (SO) coupling effects. We find that the structure of the ? reactant has a substantial effect on the role of the SO coupling on the reaction energy. Both the BHandH and MP2 theories with an ECP/6-31++G** basis set, and without SO coupling corrections, provide accurate models for the reaction energetics. MP2 theory gives an unsymmetric structure with different C-I bond lengths, resulting in a SO energy for ? similar to that for the product I-atom and a negligible SO correction to the reaction energy. In contrast, DFT gives a symmetric structure for ? , similar to that of the neutral C2H4I2 parent, resulting in a substantial SO correction and increasing the reaction energy by 6.0-6.5 kcalmol-1. Also, we find that, for this system, coupled-cluster single-point energy calculations are inaccurate, since a small change in geometry can lead to a large change in energy.

  6. POTENTIAL DISTRIBUTION OF ORANGE JASMINE (Murraya paniculata IN MEXICO

    Directory of Open Access Journals (Sweden)

    José López-Collado

    2013-04-01

    Full Text Available Orange jasmine (OJ is a common ornamental plant used as green hedge in public and private gardens in Mexico. It also hosts Huanglongbing, a worldwide citrus disease and its vector, Diaphorina citri. For risk analysis and management purpose is important to know its geographic distribution. The potential distribution of OJ was calculated in Mexico using a deductive approach. Based on temperature and precipitation requirements, a relative suitability index was computed by combining the normalized values of both variables. The distribution was overlapped with captures of D. citri to check their spatial similarity. The results showed that the potential of occurrence is high in the Pacific and Gulf of México coastal states, including the Yucatán peninsula, and the lowest values appeared in the north-western states. The OJ distribution overlaps with Huanglongbing occurrence and coincided with captures of D. citri for most of the suitable area but D. citri captures extended beyond the optimal OJ distribution values in the northern regions of México.

  7. Potential utility of the thematic mapper for surface mine monitoring

    International Nuclear Information System (INIS)

    Irons, J.R.; Lachowski, H.M.

    1981-01-01

    One of many potential applications of the thematic mapper (TM) is surface mine monitoring. To assess this potential, data acquired by an aircraft multispectral scanner over Pennsylvania surface mines were preprocessed to simulate the anticipated spectral, spatial, and radiometric characteristics of TM data. False color imagery and thematic maps were derived from the simulated data and compared to imagery and maps derived from LANDSAT multispectral scanner subsystems data. On the basis of this comparison, TM data should definitely increase the detail and accuracy of remotely acquired surface mine information and may enable the remote determination of compliance with reclamation regulations

  8. Assessment of Rainfall-induced Landslide Potential and Spatial Distribution

    Science.gov (United States)

    Chen, Yie-Ruey; Tsai, Kuang-Jung; Chen, Jing-Wen; Chiang, Jie-Lun; Hsieh, Shun-Chieh; Chue, Yung-Sheng

    2016-04-01

    Recently, due to the global climate change, most of the time the rainfall in Taiwan is of short duration but with high intensity. Due to Taiwan's steep terrain, rainfall-induced landslides often occur and lead to human causalities and properties loss. Taiwan's government has invested huge reconstruction funds to the affected areas. However, after rehabilitation they still face the risk of secondary sediment disasters. Therefore, this study assesses rainfall-induced (secondary) landslide potential and spatial distribution in watershed of Southern Taiwan under extreme climate change. The study areas in this research are Baolai and Jianshan villages in the watershed of the Laonongxi River Basin in the Southern Taiwan. This study focused on the 3 years after Typhoon Morakot (2009 to 2011). During this period, the study area experienced six heavy rainfall events including five typhoons and one heavy rainfall. The genetic adaptive neural network, texture analysis and GIS were implemented in the analysis techniques for the interpretation of satellite images and to obtain surface information and hazard log data and to analyze land use change. A multivariate hazards evaluation method was applied to quantitatively analyze the weights of various natural environmental and slope development hazard factors. Furthermore, this study established a slope landslide potential assessment model and depicted a slope landslide potential diagram by using the GIS platform. The interaction between (secondary) landslide mechanism, scale, and location was analyzed using association analysis of landslide historical data and regional environmental characteristics. The results of image classification before and after six heavy rainfall events show that the values of coefficient of agreement are at medium-high level. By multivariate hazards evaluation method, geology and the effective accumulative rainfall (EAR) are the most important factors. Slope, distance from fault, aspect, land disturbance

  9. Eccentricity samples: Implications on the potential and the velocity distribution

    Directory of Open Access Journals (Sweden)

    Cubarsi R.

    2017-01-01

    Full Text Available Planar and vertical epicycle frequencies and local angular velocity are related to the derivatives up to the second order of the local potential and can be used to test the shape of the potential from stellar disc samples. These samples show a more complex velocity distribution than halo stars and should provide a more realistic test. We assume an axisymmetric potential allowing a mixture of independent ellipsoidal velocity distributions, of separable or Staeckel form in cylindrical or spherical coordinates. We prove that values of local constants are not consistent with a potential separable in addition in cylindrical coordinates and with a spherically symmetric potential. The simplest potential that fits the local constants is used to show that the harmonical and non-harmonical terms of the potential are equally important. The same analysis is used to estimate the local constants. Two families of nested subsamples selected for decreasing planar and vertical eccentricities are used to borne out the relation between the mean squared planar and vertical eccentricities and the velocity dispersions of the subsamples. According to the first-order epicycle model, the radial and vertical velocity components provide accurate information on the planar and vertical epicycle frequencies. However, it is impossible to account for the asymmetric drift which introduces a systematic bias in estimation of the third constant. Under a more general model, when the asymmetric drift is taken into account, the rotation velocity dispersions together with their asymmetric drift provide the correct fit for the local angular velocity. The consistency of the results shows that this new method based on the distribution of eccentricities is worth using for kinematic stellar samples. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. No 176011: Dynamics and Kinematics of Celestial Bodies and Systems

  10. Osteogenic potential of laser modified and conditioned titanium zirconium surfaces

    Directory of Open Access Journals (Sweden)

    P David Charles

    2016-01-01

    Full Text Available Statement of Problem: The osseointegration of dental implant is related to their composition and surface treatment. Titanium zirconium (TiZr has been introduced as an alternative to the commercially pure titanium and its alloys as dental implant material, which is attributed to its superior mechanical and biological properties. Surface treatments of TiZr have been introduced to enhance their osseointegration ability; however, reliable, easy to use surface modification technique has not been established. Purpose: The purpose of this study was to evaluate and compare the effect of neodymium-doped yttrium aluminum garnet (Nd-YAG laser surface treatment of TiZr implant alloy on their osteogenic potential. Materials and Methods: Twenty disc-shaped samples of 5 mm diameter and 2 mm height were milled from the TiZr alloy ingot. The polished discs were ultrasonically cleaned in distilled water. Ten samples each were randomly selected as Group A control samples and Group B consisted of Nd-YAG laser surface etched and conditioned test samples. These were evaluated for cellular response. Cellular adhesion and proliferation were quantified, and the results were statistically analyzed using nonparametric analysis. Cellular morphology was observed using electron and epiflurosence microscopy. Results: Nd-YAG laser surface modified and conditioned TiZr samples increased the osteogenic potential. Conclusion: Nd-YAG laser surface modification of TiZr, improves the cellular activity, surface roughness, and wettability, thereby increasing the osteogenic potential.

  11. Ab initio Potential Energy Surface for H-H2

    Science.gov (United States)

    Partridge, Harry; Bauschlicher, Charles W., Jr.; Stallcop, James R.; Levin, Eugene

    1993-01-01

    Ab initio calculations employing large basis sets are performed to determine an accurate potential energy surface for H-H2 interactions for a broad range of separation distances. At large distances, the spherically averaged potential determined from the calculated energies agrees well with the corresponding results determined from dispersion coefficients; the van der Waals well depth is predicted to be 75 +/- (mu)E(sub h). Large basis sets have also been applied to reexamine the accuracy of theoretical repulsive potential energy surfaces. Multipolar expansions of the computed H-H2 potential energy surface are reported for four internuclear separation distances (1.2, 1.401, 1.449, and 1.7a(sub 0) of the hydrogen molecule. The differential elastic scattering cross section calculated from the present results is compared with the measurements from a crossed beam experiment.

  12. Disordered electrical potential observed on the surface of SiO2 by electric field microscopy

    International Nuclear Information System (INIS)

    GarcIa, N; Yan Zang; Ballestar, A; Barzola-Quiquia, J; Bern, F; Esquinazi, P

    2010-01-01

    The electrical potential on the surface of ∼300 nm thick SiO 2 grown on single-crystalline Si substrates has been characterized at ambient conditions using electric field microscopy. Our results show an inhomogeneous potential distribution with fluctuations up to ∼0.4 V within regions of 1 μm. The potential fluctuations observed at the surface of these usual dielectric holders of graphene sheets should induce strong variations in the graphene charge densities and provide a simple explanation for some of the anomalous behaviors of the transport properties of graphene.

  13. Statistical modelling of a new global potential vegetation distribution

    Science.gov (United States)

    Levavasseur, G.; Vrac, M.; Roche, D. M.; Paillard, D.

    2012-12-01

    The potential natural vegetation (PNV) distribution is required for several studies in environmental sciences. Most of the available databases are quite subjective or depend on vegetation models. We have built a new high-resolution world-wide PNV map using a objective statistical methodology based on multinomial logistic models. Our method appears as a fast and robust alternative in vegetation modelling, independent of any vegetation model. In comparison with other databases, our method provides a realistic PNV distribution in agreement with respect to BIOME 6000 data. Among several advantages, the use of probabilities allows us to estimate the uncertainty, bringing some confidence in the modelled PNV, or to highlight the regions needing some data to improve the PNV modelling. Despite our PNV map being highly dependent on the distribution of data points, it is easily updatable as soon as additional data are available and provides very useful additional information for further applications.

  14. Leptospirosis in Mexico: Epidemiology and Potential Distribution of Human Cases

    Science.gov (United States)

    Sánchez-Montes, Sokani; Espinosa-Martínez, Deborah V.; Ríos-Muñoz, César A.; Berzunza-Cruz, Miriam; Becker, Ingeborg

    2015-01-01

    Background Leptospirosis is widespread in Mexico, yet the potential distribution and risk of the disease remain unknown. Methodology/Principal Findings We analysed morbidity and mortality according to age and gender based on three sources of data reported by the Ministry of Health and the National Institute of Geography and Statics of Mexico, for the decade 2000–2010. A total of 1,547 cases were reported in 27 states, the majority of which were registered during the rainy season, and the most affected age group was 25–44 years old. Although leptospirosis has been reported as an occupational disease of males, analysis of morbidity in Mexico showed no male preference. A total number of 198 deaths were registered in 21 states, mainly in urban settings. Mortality was higher in males (61.1%) as compared to females (38.9%), and the case fatality ratio was also increased in males. The overall case fatality ratio in Mexico was elevated (12.8%), as compared to other countries. We additionally determined the potential disease distribution by examining the spatial epidemiology combined with spatial modeling using ecological niche modeling techniques. We identified regions where leptospirosis could be present and created a potential distribution map using bioclimatic variables derived from temperature and precipitation. Our data show that the distribution of the cases was more related to temperature (75%) than to precipitation variables. Ecological niche modeling showed predictive areas that were widely distributed in central and southern Mexico, excluding areas characterized by extreme climates. Conclusions/Significance In conclusion, an epidemiological surveillance of leptospirosis is recommended in Mexico, since 55.7% of the country has environmental conditions fulfilling the criteria that favor the presence of the disease. PMID:26207827

  15. Leptospirosis in Mexico: Epidemiology and Potential Distribution of Human Cases.

    Directory of Open Access Journals (Sweden)

    Sokani Sánchez-Montes

    Full Text Available Leptospirosis is widespread in Mexico, yet the potential distribution and risk of the disease remain unknown.We analysed morbidity and mortality according to age and gender based on three sources of data reported by the Ministry of Health and the National Institute of Geography and Statics of Mexico, for the decade 2000-2010. A total of 1,547 cases were reported in 27 states, the majority of which were registered during the rainy season, and the most affected age group was 25-44 years old. Although leptospirosis has been reported as an occupational disease of males, analysis of morbidity in Mexico showed no male preference. A total number of 198 deaths were registered in 21 states, mainly in urban settings. Mortality was higher in males (61.1% as compared to females (38.9%, and the case fatality ratio was also increased in males. The overall case fatality ratio in Mexico was elevated (12.8%, as compared to other countries. We additionally determined the potential disease distribution by examining the spatial epidemiology combined with spatial modeling using ecological niche modeling techniques. We identified regions where leptospirosis could be present and created a potential distribution map using bioclimatic variables derived from temperature and precipitation. Our data show that the distribution of the cases was more related to temperature (75% than to precipitation variables. Ecological niche modeling showed predictive areas that were widely distributed in central and southern Mexico, excluding areas characterized by extreme climates.In conclusion, an epidemiological surveillance of leptospirosis is recommended in Mexico, since 55.7% of the country has environmental conditions fulfilling the criteria that favor the presence of the disease.

  16. Water potential distribution in the testing soil column

    International Nuclear Information System (INIS)

    Yao Laigen; Zhao Yingjie

    2000-01-01

    The author explains the water potential distribution in the testing soil column under artificial sprinkling condition and confirm that the nuclide migration is carried out under the unsaturated condition. Knowing well the situation of water permeation in the unsaturated zone is one of main research works. The testing material and size of soil column used is very similar to the No.4 soil column for nuclide migration test. Under the same sprinkling condition as simulation test for nuclide migration, the water potential distribution in the soil column was measured. The test result shows that during the test process in upper 40 cm scope of soil column the unsaturated condition is kept from beginning to end

  17. Potential geographic distribution of hantavirus reservoirs in Brazil.

    Science.gov (United States)

    de Oliveira, Stefan Vilges; Escobar, Luis E; Peterson, A Townsend; Gurgel-Gonçalves, Rodrigo

    2013-01-01

    Hantavirus cardiopulmonary syndrome is an emerging zoonosis in Brazil. Human infections occur via inhalation of aerosolized viral particles from excreta of infected wild rodents. Necromys lasiurus and Oligoryzomys nigripes appear to be the main reservoirs of hantavirus in the Atlantic Forest and Cerrado biomes. We estimated and compared ecological niches of the two rodent species, and analyzed environmental factors influencing their occurrence, to understand the geography of hantavirus transmission. N. lasiurus showed a wide potential distribution in Brazil, in the Cerrado, Caatinga, and Atlantic Forest biomes. Highest climate suitability for O. nigripes was observed along the Brazilian Atlantic coast. Maximum temperature in the warmest months and annual precipitation were the variables that most influence the distributions of N. lasiurus and O. nigripes, respectively. Models based on occurrences of infected rodents estimated a broader area of risk for hantavirus transmission in southeastern and southern Brazil, coinciding with the distribution of human cases of hantavirus cardiopulmonary syndrome. We found no demonstrable environmental differences among occurrence sites for the rodents and for human cases of hantavirus. However, areas of northern and northeastern Brazil are also apparently suitable for the two species, without broad coincidence with human cases. Modeling of niches and distributions of rodent reservoirs indicates potential for transmission of hantavirus across virtually all of Brazil outside the Amazon Basin.

  18. Potential geographic distribution of hantavirus reservoirs in Brazil.

    Directory of Open Access Journals (Sweden)

    Stefan Vilges de Oliveira

    Full Text Available Hantavirus cardiopulmonary syndrome is an emerging zoonosis in Brazil. Human infections occur via inhalation of aerosolized viral particles from excreta of infected wild rodents. Necromys lasiurus and Oligoryzomys nigripes appear to be the main reservoirs of hantavirus in the Atlantic Forest and Cerrado biomes. We estimated and compared ecological niches of the two rodent species, and analyzed environmental factors influencing their occurrence, to understand the geography of hantavirus transmission. N. lasiurus showed a wide potential distribution in Brazil, in the Cerrado, Caatinga, and Atlantic Forest biomes. Highest climate suitability for O. nigripes was observed along the Brazilian Atlantic coast. Maximum temperature in the warmest months and annual precipitation were the variables that most influence the distributions of N. lasiurus and O. nigripes, respectively. Models based on occurrences of infected rodents estimated a broader area of risk for hantavirus transmission in southeastern and southern Brazil, coinciding with the distribution of human cases of hantavirus cardiopulmonary syndrome. We found no demonstrable environmental differences among occurrence sites for the rodents and for human cases of hantavirus. However, areas of northern and northeastern Brazil are also apparently suitable for the two species, without broad coincidence with human cases. Modeling of niches and distributions of rodent reservoirs indicates potential for transmission of hantavirus across virtually all of Brazil outside the Amazon Basin.

  19. Distribution of genes associated with yield potential and water ...

    Indian Academy of Sciences (India)

    2B, TaGW2-6A and Dreb-B1 genes conferring to yield potential and water-saving were selected to analyse the distribution in. 102 wheat varieties, most of which were authorized in the past decade and adapted to grow in Zone II of China. First, the semi- dwarfing genes Rht-B1b and Rht-D1b (mutant alleles) conferring to ...

  20. Dependence of the runaway greenhouse threshold on the surface water distribution for Earth-like planets

    Science.gov (United States)

    Kodama, T.; Nitta, A.; Genda, H.; Oishi, R.; Abe-Ouchi, A.; Abe, Y.

    2017-12-01

    Liquid water is one of the important materials that affect the climate and habitability on a terrestrial planet. Liquid water entirely vaporizes when planets receive insolation above a certain critical value, which is called the runaway greenhouse threshold. This threshold forms the inner most limit of the habitable zone. In general, it is assumed that an Earth-like planet with oceans is a potentially habitable planet. Such a planet is implicitly assumed to be a planet whose surface is covered with oceans. Thus, most of previous studies estimated the runaway greenhouse threshold for such planets. Abe et al. (2011) suggest that the runaway greenhouse threshold significantly depends on the distribution of water on the surface. The distribution of the surface water is determined by the surface topography, the surface water flow and the transport of water vapor in the atmosphere. Here, we investigate the effects of the distribution of surface water on the runaway greenhouse threshold for Earth-sized planets using a three-dimensional dynamic atmosphere model. We recognized two climate regimes: the land planet regime, which has dry low latitude and wet high latitude regions, and the aqua planet regime, which is globally wet. We showed that each regime is controlled by the width of the Hadley circulation, the amount of surface water, and the planetary topography. We found that the runaway greenhouse threshold continuously varies with the surface water distribution from about 130% (an aqua planet) to 180% (the extreme case of a land planet) of the present insolation at Earth's orbit. Our results indicate that the inner edge of the habitable zone is not a single sharp boundary, but a border whose location varies depending on planetary surface condition, such as the amount of surface water.

  1. Intermolecular potential energy surface for CS2 dimer.

    Science.gov (United States)

    Farrokhpour, Hossein; Mombeini, Zainab; Namazian, Mansoor; Coote, Michelle L

    2011-04-15

    A new four-dimensional intermolecular potential energy surface for CS(2) dimer is obtained by ab initio calculation of the interaction energies for a range of configurations and center-of-mass separation distances for the first time. The calculations were performed using the supermolecular approach at the Møller-Plesset second-order perturbation (MP2) level of theory with the augmented correlation consistent basis sets (aug-cc-pVxZ, x = D, T) and corrected for the basis-set superposition error using the full counterpoise correction method. A two-point extrapolation method was used to extrapolate the calculated energy points to the complete basis set limit. The effect of using the higher levels of theory, quadratic configuration interaction containing single, double, and perturbative triple excitations QCISD(T) and coupled cluster singles, doubles and perturbative triples excitations CCSD(T), on the shape of potential energy surface was investigated. It is shown that the MP2 level of theory apparently performs extremely poorly for describing the intermolecular potential energy surface, overestimating the total energy by a factor of nearly 1.73 in comparison with the QCISD(T) and CCSD(T) values. The value of isotropic dipole-dipole dispersion coefficient (C(6) ) of CS(2) fluid was obtained from the extrapolated MP2 potential energy surface. The MP2 extrapolated energy points were fitted to well-known analytical potential functions using two different methods to represent the potential energy surface analytically. The most stable configuration of the dimer was determined at R = 6.23 au, α = 90°, β = 90°, and γ = 90°, with a well depth of 3.980 kcal mol(-1) at the MP2 level of theory. Finally, the calculated second virial coefficients were compared with experimental values to test the quality of the presented potential energy surface. Copyright © 2010 Wiley Periodicals, Inc.

  2. The Contribution of Surface Potential to Diverse Problems in Electrostatics

    Science.gov (United States)

    Horenstein, M.

    2015-10-01

    Electrostatics spans many different subject areas. Some comprise “good electrostatics,” where charge is used for desirable purposes. Such areas include industrial manufacturing, electrophotography, surface modification, precipitators, aerosol control, and MEMS. Other areas comprise “bad electrostatics,” where charge is undesirable. Such areas include hazardous discharges, ESD, health effects, nuisance triboelectrification, particle contamination, and lightning. Conference proceedings such as this one inevitably include papers grouped around these topics. One common thread throughout is the surface potential developed when charge resides on an insulator surface. Often, the charged insulator will be in intimate contact with a ground plane. At other times, the charged insulator will be isolated. In either case, the resulting surface potential is important to such processes as propagating brush discharges, charge along a moving web, electrostatic biasing effects in MEMS, non-contacting voltmeters, field-effect transistor sensors, and the maximum possible charge on a woven fabric.

  3. An atlas of monthly mean distributions of GEOSAT sea surface height, SSMI surface wind speed, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1988

    Science.gov (United States)

    Halpern, D.; Zlotnicki, V.; Newman, J.; Brown, O.; Wentz, F.

    1991-01-01

    Monthly mean global distributions for 1988 are presented with a common color scale and geographical map. Distributions are included for sea surface height variation estimated from GEOSAT; surface wind speed estimated from the Special Sensor Microwave Imager on the Defense Meteorological Satellite Program spacecraft; sea surface temperature estimated from the Advanced Very High Resolution Radiometer on NOAA spacecrafts; and the Cartesian components of the 10m height wind vector computed by the European Center for Medium Range Weather Forecasting. Charts of monthly mean value, sampling distribution, and standard deviation value are displayed. Annual mean distributions are displayed.

  4. Surface potential domains on lamellar P3OT structures

    International Nuclear Information System (INIS)

    Perez-GarcIa, B; Abad, J; Urbina, A; Colchero, J; Palacios-Lidon, E

    2008-01-01

    In this work the electrostatic properties of poly(3-octylthiophene) thin films have been studied on a nanometer scale by means of electrostatic force microscopy and Kelvin probe microscopy (KPM). The KPM images reveal that different surface contact potential domains coexist on the polymer surface. This result, together with additional capacitance measurements, indicates that the potential domains are related to the existence of dipoles due to different molecular arrangements. Finally, capacitance measurements as a function of the tip-sample bias voltage show that in all regions large band bending effects take place

  5. Surface potential domains on lamellar P3OT structures

    Energy Technology Data Exchange (ETDEWEB)

    Perez-GarcIa, B [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain); Abad, J [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain); Urbina, A [Departamento Electronica, TecnologIa de Computadoras y Proyectos, Universidad Politecnica de Cartagena, E-30202 Cartagena (Spain); Colchero, J [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain); Palacios-Lidon, E [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain)

    2008-02-13

    In this work the electrostatic properties of poly(3-octylthiophene) thin films have been studied on a nanometer scale by means of electrostatic force microscopy and Kelvin probe microscopy (KPM). The KPM images reveal that different surface contact potential domains coexist on the polymer surface. This result, together with additional capacitance measurements, indicates that the potential domains are related to the existence of dipoles due to different molecular arrangements. Finally, capacitance measurements as a function of the tip-sample bias voltage show that in all regions large band bending effects take place.

  6. He-, Ne-, and Ar-phosgene intermolecular potential energy surfaces

    DEFF Research Database (Denmark)

    Munteanu, Cristian R.; Henriksen, Christian; Felker, Peter M.

    2013-01-01

    Using the CCSD(T) model, we evaluated the intermolecular potential energy surfaces of the He-, Ne-, and Ar-phosgene complexes. We considered a representative number of intermolecular geometries for which we calculated the corresponding interaction energies with the augmented (He complex) and double......-phosgene surfaces were found to have absolute minima of -72.1, -140.4, and -326.6 cm -1 at distances between the rare-gas atom and the phosgene center of mass of 3.184, 3.254, and 3.516 Å, respectively. The potentials were further used in the evaluation of rovibrational states and the rotational constants...

  7. An adaptive interpolation scheme for molecular potential energy surfaces

    Science.gov (United States)

    Kowalewski, Markus; Larsson, Elisabeth; Heryudono, Alfa

    2016-08-01

    The calculation of potential energy surfaces for quantum dynamics can be a time consuming task—especially when a high level of theory for the electronic structure calculation is required. We propose an adaptive interpolation algorithm based on polyharmonic splines combined with a partition of unity approach. The adaptive node refinement allows to greatly reduce the number of sample points by employing a local error estimate. The algorithm and its scaling behavior are evaluated for a model function in 2, 3, and 4 dimensions. The developed algorithm allows for a more rapid and reliable interpolation of a potential energy surface within a given accuracy compared to the non-adaptive version.

  8. Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials

    KAUST Repository

    Mutoro, Eva

    2012-01-05

    Perovskite oxides can exhibit a wide range of interesting characteristics such as being catalytically active and electronically/ionically conducting, and thus, they have been used in a number of solid-state devices such as solid oxide fuel cells (SOFCs) and sensors. As the surface compositions of perovskites can greatly influence the catalytic properties, knowing and controlling their surface compositions is crucial to enhance device performance. In this study, we demonstrate that the surface strontium (Sr) and cobalt (Co) concentrations of perovskite-based thin films can be controlled reversibly at elevated temperatures by applying small electrical potential biases. The surface compositional changes of La 0.8Sr 0.2CoO 3-δ (LSC 113), (La 0.5Sr 0.5) 2CoO 4±δ (LSC 214), and LSC 214-decorated LSC 113 films (LSC 113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr were found for the LSC 113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites. © 2011 American Chemical Society.

  9. Ride control of surface effect ships using distributed control

    Directory of Open Access Journals (Sweden)

    Asgeir J. Sørensen

    1994-04-01

    Full Text Available A ride control system for active damping of heave and pitch accelerations of Surface Effect Ships (SES is presented. It is demonstrated that distributed effects that are due to a spatially varying pressure in the air cushion result in significant vertical vibrations in low and moderate sea states. In order to achieve a high quality human comfort and crew workability it is necessary to reduce these vibrations using a control system which accounts for distributed effects due to spatial pressure variations in the air cushion. A mathematical model of the process is presented, and collocated sensor and actuator pairs are used. The process stability is ensured using a controller with appropriate passivity properties. Sensor and actuator location is also discussed. The performance of the ride control system is shown by power spectra of the vertical accelerations obtained from full scale experiments with a 35 m SES.

  10. Internal state distributions of molecules scattering and desorbing from surfaces

    International Nuclear Information System (INIS)

    Auerbach, D.J.

    1983-01-01

    Attempts are made to interpret scattering experiments of NO molecules on Ag(111) where a (rotational) state-specific detector has been used. A model using an anisotropic potential is proposed to explain the observed incoming energy- and angle dependence. The so-called rotational rainbows are explained. It is concluded, that in this way information on intermolecular potentials and the transfer of translational to rotational energy in the dynamics of trapping and sticking of molecules on surfaces can be extracted. (G.Q.)

  11. Effective medium potentials for molecule-surface interactions: H2 on Cu and Ni surfaces

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet

    1989-01-01

    outside metal surfaces and the applicability is illustrated for H2 adsorbing on various Cu and Ni surfaces. Although very approximate, the calculated potentials seem to include a number of features observed experimentally: Ni is more active in dissociating H2 than Cu, and open surfaces are more active...... than close-packed ones. Moreover, the method is simple enough that one can contemplate studying variations in dissociation pathways over the surface unit cell. For the Cu surfaces these variations are substantial accounting for at least part of the variation of the sticking coefficient with the kinetic...

  12. Lunar Surface Potential Increases during Terrestrial Bow Shock Traversals

    Science.gov (United States)

    Collier, Michael R.; Stubbs, Timothy J.; Hills, H. Kent; Halekas, Jasper; Farrell, William M.; Delory, Greg T.; Espley, Jared; Freeman, John W.; Vondrak, Richard R.; Kasper, Justin

    2009-01-01

    Since the Apollo era the electric potential of the Moon has been a subject of interest and debate. Deployed by three Apollo missions, Apollo 12, Apollo 14 and Apollo 15, the Suprathermal Ion Detector Experiment (SIDE) determined the sunlit lunar surface potential to be about +10 Volts using the energy spectra of lunar ionospheric thermal ions accelerated toward the Moon. We present an analysis of Apollo 14 SIDE "resonance" events that indicate the lunar surface potential increases when the Moon traverses the dawn bow shock. By analyzing Wind spacecraft crossings of the terrestrial bow shock at approximately this location and employing current balancing models of the lunar surface, we suggest causes for the increasing potential. Determining the origin of this phenomenon will improve our ability to predict the lunar surface potential in support of human exploration as well as provide models for the behavior of other airless bodies when they traverse similar features such as interplanetary shocks, both of which are goals of the NASA Lunar Science Institute's Dynamic Response of the Environment At the Moon (DREAM) team.

  13. Surface potential of the water liquid-vapor interface

    Science.gov (United States)

    Wilson, Michael A.; Pohorille, Andrew; Pratt, Lawrence R.

    1988-01-01

    An analysis of an extended molecular dynamics calculation of the surface potential (SP) of the water liquid-vapor interface is presented. The SP predicted by the TIP4P model is -(130 + or - 50) mV. This value is of reasonable magnitude but of opposite sign to the expectations based on laboratory experiments. The electrostatic potential shows a nonmonotonic variation with depth into the liquid.

  14. Potential impacts of climatic change upon geographical distributions of birds

    DEFF Research Database (Denmark)

    Huntley, Brian; Collingham, Yvonne C.; Green, Rhys E.

    2006-01-01

    biodiversity. Birds, in common with other terrestrial organisms, are expected to exhibit one of two general responses to climatic change: they may adapt to the changed conditions without shifting location, or they may show a spatial response, adjusting their geographical distribution in response...... to achieve a sufficient response by either or both of these mechanisms will be at risk of extinction; the Quaternary record documents examples of such extinctions. Relationships between the geographical distributions of birds and present climate have been modelled for species breeding in both Europe...... and Africa. The resulting models have very high goodness-of-fit and provide a basis for assessing the potential impacts of anthropogenic climatic changes upon avian species richness in the two continents. Simulations made for a range of general circulation model projections of late 21st century climate lead...

  15. Data-driven mapping of the potential mountain permafrost distribution.

    Science.gov (United States)

    Deluigi, Nicola; Lambiel, Christophe; Kanevski, Mikhail

    2017-07-15

    Existing mountain permafrost distribution models generally offer a good overview of the potential extent of this phenomenon at a regional scale. They are however not always able to reproduce the high spatial discontinuity of permafrost at the micro-scale (scale of a specific landform; ten to several hundreds of meters). To overcome this lack, we tested an alternative modelling approach using three classification algorithms belonging to statistics and machine learning: Logistic regression, Support Vector Machines and Random forests. These supervised learning techniques infer a classification function from labelled training data (pixels of permafrost absence and presence) with the aim of predicting the permafrost occurrence where it is unknown. The research was carried out in a 588km 2 area of the Western Swiss Alps. Permafrost evidences were mapped from ortho-image interpretation (rock glacier inventorying) and field data (mainly geoelectrical and thermal data). The relationship between selected permafrost evidences and permafrost controlling factors was computed with the mentioned techniques. Classification performances, assessed with AUROC, range between 0.81 for Logistic regression, 0.85 with Support Vector Machines and 0.88 with Random forests. The adopted machine learning algorithms have demonstrated to be efficient for permafrost distribution modelling thanks to consistent results compared to the field reality. The high resolution of the input dataset (10m) allows elaborating maps at the micro-scale with a modelled permafrost spatial distribution less optimistic than classic spatial models. Moreover, the probability output of adopted algorithms offers a more precise overview of the potential distribution of mountain permafrost than proposing simple indexes of the permafrost favorability. These encouraging results also open the way to new possibilities of permafrost data analysis and mapping. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Distribution of potentially hazardous phases in the subsurface at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Guthrie, G.D. Jr.; Bish, D.L.; Chipera, S.J.; Raymond, R. Jr.

    1995-05-01

    Drilling, trenching, excavation of the Exploratory Studies Facility, and other surface and underground-distributing activities have the potential to release minerals into the environment from tuffs at Yucca Mountain, Nevada. Some of these minerals may be potential respiratory health hazards. Therefore, an understanding of the distribution of the minerals that may potentially be liberated during site-characterization and operation of the potential repository is crucial to ensuring worker and public safety. Analysis of previously reported mineralogy of Yucca Mountain tuffs using data and criteria from the International Agency for Research on Cancer (IARC) suggests that the following minerals are of potential concern: quartz, cristobalite, tridymite, opal-CT, erionite, mordenite, and palygorskite. The authors have re-evaluated the three-dimensional mineral distribution at Yucca Mountain above the static water level both in bulk-rock samples and in fractures, using quantitative X-ray powder diffraction analysis. Erionite, mordenite, and palygorskite occur primarily in fractures; the crystalline-silica minerals, quartz, cristobalite, and tridymite are major bulk-rock phases. Erionite occurs in the altered zone just above the lower Topopah Spring Member vitrophyre, and an occurrence below the vitrophyre but above the Calico Hills has recently been identified. In this latter occurrence, erionite is present in the matrix at levels up to 35 wt%. Mordenite and palygorskite occur throughout the vadose zone nearly to the surface. Opal-CT is limited to zeolitic horizons

  17. Distribution of potentially hazardous phases in the subsurface at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Guthrie, G.D. Jr.; Bish, D.L.; Chipera, S.J.; Raymond, R. Jr.

    1995-05-01

    Drilling, trenching, excavation of the Exploratory Studies Facility, and other surface and underground-distributing activities have the potential to release minerals into the environment from tuffs at Yucca Mountain, Nevada. Some of these minerals may be potential respiratory health hazards. Therefore, an understanding of the distribution of the minerals that may potentially be liberated during site-characterization and operation of the potential repository is crucial to ensuring worker and public safety. Analysis of previously reported mineralogy of Yucca Mountain tuffs using data and criteria from the International Agency for Research on Cancer (IARC) suggests that the following minerals are of potential concern: quartz, cristobalite, tridymite, opal-CT, erionite, mordenite, and palygorskite. The authors have re-evaluated the three-dimensional mineral distribution at Yucca Mountain above the static water level both in bulk-rock samples and in fractures, using quantitative X-ray powder diffraction analysis. Erionite, mordenite, and palygorskite occur primarily in fractures; the crystalline-silica minerals, quartz, cristobalite, and tridymite are major bulk-rock phases. Erionite occurs in the altered zone just above the lower Topopah Spring Member vitrophyre, and an occurrence below the vitrophyre but above the Calico Hills has recently been identified. In this latter occurrence, erionite is present in the matrix at levels up to 35 wt%. Mordenite and palygorskite occur throughout the vadose zone nearly to the surface. Opal-CT is limited to zeolitic horizons.

  18. Effects of geometric modulation and surface potential heterogeneity on electrokinetic flow and solute transport in a microchannel

    Science.gov (United States)

    Bera, Subrata; Bhattacharyya, S.

    2018-04-01

    A numerical investigation is performed on the electroosmotic flow (EOF) in a surface-modulated microchannel to induce enhanced solute mixing. The channel wall is modulated by placing surface-mounted obstacles of trigonometric shape along which the surface potential is considered to be different from the surface potential of the homogeneous part of the wall. The characteristics of the electrokinetic flow are governed by the Laplace equation for the distribution of external electric potential; the Poisson equation for the distribution of induced electric potential; the Nernst-Planck equations for the distribution of ions; and the Navier-Stokes equations for fluid flow simultaneously. These nonlinear coupled set of governing equations are solved numerically by a control volume method over the staggered system. The influence of the geometric modulation of the surface, surface potential heterogeneity and the bulk ionic concentration on the EOF is analyzed. Vortical flow develops near a surface modulation, and it becomes stronger when the surface potential of the modulated region is in opposite sign to the surface potential of the homogeneous part of the channel walls. Vortical flow also depends on the Debye length when the Debye length is in the order of the channel height. Pressure drop along the channel length is higher for a ribbed wall channel compared to the grooved wall case. The pressure drop decreases with the increase in the amplitude for a grooved channel, but increases for a ribbed channel. The mixing index is quantified through the standard deviation of the solute distribution. Our results show that mixing index is higher for the ribbed channel compared to the grooved channel with heterogeneous surface potential. The increase in potential heterogeneity in the modulated region also increases the mixing index in both grooved and ribbed channels. However, the mixing performance, which is the ratio of the mixing index to pressure drop, reduces with the rise in

  19. Tuning the surface potential of Ag surfaces by chemisorption of oppositely-oriented thiolated carborane dipoles

    Czech Academy of Sciences Publication Activity Database

    Lübben, J.F.; Baše, Tomáš; Rupper, P.; Künniger, T.; Macháček, Jan; Guimond, S.

    2011-01-01

    Roč. 354, č. 1 (2011), s. 168-174 ISSN 0021-9797 R&D Projects: GA AV ČR(CZ) IAA400320901 Keywords : Adsorption * Thiolated carboranes * Silver surface * Surface potential * X-ray photoelectron spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 3.070, year: 2011

  20. Agronomic potential of some agricultural wastes as surface mulches ...

    African Journals Online (AJOL)

    Studies were carried out at the Teaching and Research Farm of the University of Cape Coast, in the minor seasons of 1992 and 1993, to assess the agronomic potential of some common agricultural wastes as surface mulches in terms of weed control, nematode population in soil, root-knot incidence and growth and yield of ...

  1. Second order classical perturbation theory for atom surface scattering: analysis of asymmetry in the angular distribution.

    Science.gov (United States)

    Zhou, Yun; Pollak, Eli; Miret-Artés, Salvador

    2014-01-14

    A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to "soft" corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.

  2. Probability distribution of surface wind speed induced by convective adjustment on Venus

    Science.gov (United States)

    Yamamoto, Masaru

    2017-03-01

    The influence of convective adjustment on the spatial structure of Venusian surface wind and probability distribution of its wind speed is investigated using an idealized weather research and forecasting model. When the initially uniform wind is much weaker than the convective wind, patches of both prograde and retrograde winds with scales of a few kilometers are formed during active convective adjustment. After the active convective adjustment, because the small-scale convective cells and their related vertical momentum fluxes dissipate quickly, the large-scale (>4 km) prograde and retrograde wind patches remain on the surface and in the longitude-height cross-section. This suggests the coexistence of local prograde and retrograde flows, which may correspond to those observed by Pioneer Venus below 10 km altitude. The probability distributions of surface wind speed V during the convective adjustment have a similar form in different simulations, with a sharp peak around ∼0.1 m s-1 and a bulge developing on the flank of the probability distribution. This flank bulge is associated with the most active convection, which has a probability distribution with a peak at the wind speed 1.5-times greater than the Weibull fitting parameter c during the convective adjustment. The Weibull distribution P(> V) (= exp[-(V/c)k]) with best-estimate coefficients of Lorenz (2016) is reproduced during convective adjustments induced by a potential energy of ∼7 × 107 J m-2, which is calculated from the difference in total potential energy between initially unstable and neutral states. The maximum vertical convective heat flux magnitude is proportional to the potential energy of the convective adjustment in the experiments with the initial unstable-layer thickness altered. The present work suggests that convective adjustment is a promising process for producing the wind structure with occasionally generating surface winds of ∼1 m s-1 and retrograde wind patches.

  3. Constructing ab initio and empirical potential energy surfaces for water

    International Nuclear Information System (INIS)

    Kain, Jacqueline Sophie

    2001-01-01

    The infrared spectrum of water is possibly one of the most well studied and yet portions of it are still poorly understood. Recently, significant advances have been made in assigning water spectra using variational nuclear calculations. The major factor determining the accuracy of ro-vibrational spectra of water is the accuracy of the underlying Potential Energy Surface. Even the most accurate ab initio Potential Energy Surface does not reproduce the Born-Oppenheimer surface to sufficient accuracy for spectroscopic studies. Furthermore, effects beyond this model such as the adiabatic correction, the relativistic correction and the non-adiabatic correction have to be considered. This thesis includes a discussion on how the relativistic correction was calculated, for the water molecule, from first-order perturbation theory. The relativistic correction improved vibrational stretching motion while making the prediction of the bending modes far worse. For rotational motion the relativistic effect had an increasing effect with increasing Ka. A further alteration to the ab initio calculations is introduced by adjusting the barrier to linearity in the water potential. This alteration to the barrier was considered in order to compensate for the lack of convergence of quantum chemical calculations of the Born-Oppenheimer surface. This barrier attempts to represent the change in the potential from linear to equilibrium. We show the improvements this has on the calculated energy levels by comparison with the HITRAN database. This then led the way to the improved spectroscopic potential presented here in this thesis. This new spectroscopic potential reduces the overall standard deviation significantly for vibrational and rotational energy levels. (author)

  4. Can atom-surface potential measurements test atomic structure models?

    Science.gov (United States)

    Lonij, Vincent P A; Klauss, Catherine E; Holmgren, William F; Cronin, Alexander D

    2011-06-30

    van der Waals (vdW) atom-surface potentials can be excellent benchmarks for atomic structure calculations. This is especially true if measurements are made with two different types of atoms interacting with the same surface sample. Here we show theoretically how ratios of vdW potential strengths (e.g., C₃(K)/C₃(Na)) depend sensitively on the properties of each atom, yet these ratios are relatively insensitive to properties of the surface. We discuss how C₃ ratios depend on atomic core electrons by using a two-oscillator model to represent the contribution from atomic valence electrons and core electrons separately. We explain why certain pairs of atoms are preferable to study for future experimental tests of atomic structure calculations. A well chosen pair of atoms (e.g., K and Na) will have a C₃ ratio that is insensitive to the permittivity of the surface, whereas a poorly chosen pair (e.g., K and He) will have a ratio of C₃ values that depends more strongly on the permittivity of the surface.

  5. Surface potential measurement of insulators in negative-ion implantation by secondary electron energy-peak shift

    International Nuclear Information System (INIS)

    Nagumo, Shoji; Toyota, Yoshitaka; Tsuji, Hiroshi; Gotoh, Yasuhito; Ishikawa, Junzo; Sakai, Shigeki; Tanjyo, Masayasu; Matsuda, Kohji.

    1993-01-01

    Negative-ion implantation is expected to realize charge-up free implantation. In this article, about a way to specify surface potential of negative-ion implanted insulator by secondary-electron-energy distribution, its principle and preliminary experimental results are described. By a measuring system with retarding field type energy analyzer, energy distribution of secondary electron from insulator of Fused Quartz in negative-carbon-ion implantation was measured. As a result the peak-shift of its energy distribution resulted according with the surface potential of insulator. It was found that surface potential of insulator is negatively charged by only several volts. Thus, negative-ion implanted insulator reduced its surface charge-up potential (without any electron supply). Therefore negative-ion implantation is considered to be much more effective method than conventional positive-ion implantation. (author)

  6. Deepwater Horizon - Estimating surface oil volume distribution in real time

    Science.gov (United States)

    Lehr, B.; Simecek-Beatty, D.; Leifer, I.

    2011-12-01

    Spill responders to the Deepwater Horizon (DWH) oil spill required both the relative spatial distribution and total oil volume of the surface oil. The former was needed on a daily basis to plan and direct local surface recovery and treatment operations. The latter was needed less frequently to provide information for strategic response planning. Unfortunately, the standard spill observation methods were inadequate for an oil spill this size, and new, experimental, methods, were not ready to meet the operational demands of near real-time results. Traditional surface oil estimation tools for large spills include satellite-based sensors to define the spatial extent (but not thickness) of the oil, complemented with trained observers in small aircraft, sometimes supplemented by active or passive remote sensing equipment, to determine surface percent coverage of the 'thick' part of the slick, where the vast majority of the surface oil exists. These tools were also applied to DWH in the early days of the spill but the shear size of the spill prevented synoptic information of the surface slick through the use small aircraft. Also, satellite images of the spill, while large in number, varied considerably in image quality, requiring skilled interpretation of them to identify oil and eliminate false positives. Qualified staff to perform this task were soon in short supply. However, large spills are often events that overcome organizational inertia to the use of new technology. Two prime examples in DWH were the application of hyper-spectral scans from a high-altitude aircraft and more traditional fixed-wing aircraft using multi-spectral scans processed by use of a neural network to determine, respectively, absolute or relative oil thickness. But, with new technology, come new challenges. The hyper-spectral instrument required special viewing conditions that were not present on a daily basis and analysis infrastructure to process the data that was not available at the command

  7. Conduction abnormalities in the right ventricular outflow tract in Brugada syndrome detected body surface potential mapping.

    Science.gov (United States)

    Guillem, Maria S; Climent, Andreu M; Millet, Jose; Berne, Paola; Ramos, Rafael; Brugada, Josep; Brugada, Ramon

    2010-01-01

    Brugada syndrome (BrS) causes sudden death in patients with structurally normal hearts. Manifestation of BrS in the ECG is dynamical and most patients do not show unequivocal signs of the syndrome during ECG screening. We have obtained 67-lead body surface potential mapping recordings of 25 patients with BrS and analyzed their spatial distribution of surface potentials during ventricular activation. Six patients presented spontaneous type I ECGs during the recording. These patients showed non-dipolarities in isopotential maps at the right ventricular outflow tract (RVOT) region during the development of terminal R waves in right precordial leads. Same finding was observed in 95% of BrS patients not presenting a type I ECG. Conduction delay in the RVOT may be a consistent finding in BrS patients that can be identified by Body Surface Potential Mapping.

  8. Formaldehyde Surface Distributions and Variability in the Mexico City Basin

    Science.gov (United States)

    Junkermann, W.; Mohr, C.; Steinbrecher, R.; Ruiz Suarez, L.

    2007-05-01

    Formaldehyde ambient air mole fractions were measured throughout the dry season in March at three different locations in the Mexico City basin. The continuously running instruments were operated at Tenago del Aire, a site located in the Chalco valley in the southern venting area of the basin, at the Intituto Mexicano del Petroleo (IMP) in the northern part of the city and about 30 km north of the city at the campus of the Universidad Tecnològica de Tecamac (UTTEC). The technique used is the Hantzsch technology with a time resolution of 2 minutes and a detection limit of 100 ppt. Daily maxima peaked at 35 ppb formaldehyde in the city and about 15 to 20 ppb at the other sites. During night formaldehyde levels dropped to about 5 ppb or less. It is evident that the observed spatial and temporal variability in near surface formaldehyde distributions is strongly affected by local and regional advection processes.

  9. Environmental conditioning on uranium surface distribution in the tropical region

    International Nuclear Information System (INIS)

    Silva, Heitor Evangelista da; Licinio, Marcus V.S.; Miranda, Marcio R.

    2001-01-01

    Based on a high resolution aerogammaspectrometer survey over the State of Rio de Janeiro, it is presented an associative study of equivalent uranium concentration and environmental parameters. The aspects considered in this study included geological domains like Sandys, Gnaisses, Granites, Xists; soils domains like Organic and Alluvial ones, Litolic, Glei, Podzolic, Red-yellow, Latossolo, Planossolo, Red bruizem, Cambissolo, Hidromorphic Podzol, Yellow latossolo; geomorphology (Coast Plains and River Accumulation Land, Coast Tabulators, Pomba-Muriae Rivers Spread Depression, Northern Mantiqueira, main Hills and Coastal Rock Massifs, Steep slopes and Reverses of Serra do Mar Mountain Range ,Serra dos Orgaos Mountain Range and Bocaina Tablelands), Paraiba do Sul Crests Alignment, Medium Paraiba do Sul Depression); influence of mean annual rain intensity and hydrographical categories were also evaluated. Geoprocessing of each environmental data base at the same cartographical base of uranium surface distribution was the basic methodology employed. (author)

  10. Measurement of Tritium Surface Distribution on TFTR Bumper Limiter Tiles

    International Nuclear Information System (INIS)

    Sugiyama, K.; Tanabe, T.; Skinner, C.H.; Gentile, C.A.

    2004-01-01

    The tritium surface distribution on graphite tiles used in the Tokamak Fusion Test Reactor (TFTR) bumper limiter and exposed to TFTR deuterium-tritium (D-T) discharges from 1993 to 1997 was measured by the Tritium Imaging Plate Technique (TIPT). The TFTR bumper limiter shows both re-/co-deposition and erosion. The tritium images for all tiles measured are strongly correlated with erosion and deposition patterns, and long-term tritium retention was found in the re-/co-depositions and flakes. The CFC tiles located at erosion dominated areas clearly showed their woven structure in their tritium images owing to different erosion yields between fibers and matrix. Significantly high tritium retention was observed on all sides of the erosion tiles, indicating carbon transport via repetition of local erosion/deposition cycles

  11. Mass Distribution and Gravitational Potential of the Milky Way

    Directory of Open Access Journals (Sweden)

    Ninković Slobodan

    2017-04-01

    Full Text Available Models of mass distribution in the Milky Way are discussed where those yielding the potential analytically are preferred. It is noted that there are three main contributors to the Milky Way potential: bulge, disc and dark halo. In the case of the disc the Miyamoto-Nagai formula, as simple enough, has shown as a very good solution, but it has not been able to satisfy all requirements. Therefore, improvements, such as adding new terms or combining several Miyamoto-Nagai terms, have been attempted. Unlike the disc, in studying the bulge and dark halo the flattening is usually neglected, which offers the possibility of obtaining an exact solution of the Poisson equation. It is emphasized that the Hernquist formula, used very often for the bulge potential, is a special case of another formula and the properties of that formula are analysed. In the case of the dark halo, the slopes of its cumulative mass for the inner and outer parts are explained through a new formalism presented here for the first time.

  12. Three-dimensional potential energy surface of Ar–CO

    Energy Technology Data Exchange (ETDEWEB)

    Sumiyoshi, Yoshihiro, E-mail: y-sumiyoshi@gunma-u.ac.jp [Division of Pure and Applied Science, Graduate School of Science and Technology, Gunma University, 4-2 Aramaki, Maebashi, Gunma 371-8510 (Japan); Endo, Yasuki [Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902 (Japan)

    2015-01-14

    A three-dimensional intermolecular potential energy surface of the Ar–CO complex has been determined by fitting most of the previously reported spectroscopic data, where observed transition frequencies by microwave, millimeter-wave, submillimeter-wave, and infrared spectroscopy were reproduced simultaneously within their experimental accuracies. A free rotor model Hamiltonian considering all the freedom of motions for an atom-diatom system was applied to calculate vibration-rotation energies. A three-dimensional potential energy surface obtained by ab initio calculations at the CCSD(T)-F12b/aug-cc-pV5Z level of theory was parameterized by a model function consisting of 46 parameters. They were used as initial values for the least-squares analysis of the experimental data. A total of 20 parameters were optimized to reproduce all the spectroscopic data.

  13. Heterogeneous and Evolving Distributions of Pluto's Volatile Surface Ices

    Science.gov (United States)

    Grundy, William M.; Olkin, C. B.; Young, L. A.; Buie, M. W.; Young, E. F.

    2013-10-01

    We report observations of Pluto's 0.8 to 2.4 µm reflectance spectrum with IRTF/SpeX on 70 nights over the 13 years from 2001 to 2013. The spectra show numerous vibrational absorption features of simple molecules CH4, CO, and N2 condensed as ices on Pluto's surface. These absorptions are modulated by the planet's 6.39 day rotation period, enabling us to constrain the longitudinal distributions of the three ices. Absorptions of CO and N2 are concentrated on Pluto's anti-Charon hemisphere, unlike absorptions of less volatile CH4 ice that are offset by roughly 90° from the longitude of maximum CO and N2 absorption. In addition to the diurnal/longitudinal variations, the spectra show longer term trends. On decadal timescales, Pluto's stronger CH4 absorption bands have deepened, while the amplitude of their diurnal variation has diminished, consistent with additional CH4 absorption by high northern latitude regions rotating into view as the sub-Earth latitude moves north (as defined by the system's angular momentum vector). Unlike the CH4 absorptions, Pluto's CO and N2 absorptions are declining over time, suggesting more equatorial or southerly distributions of those species. The authors gratefully thank the staff of IRTF for their tremendous assistance over the dozen+ years of this project. The work was funded in part by NSF grants AST-0407214 and AST-0085614 and NASA grants NAG5-4210 and NAG5-12516.

  14. Impact of vegetation growth on urban surface temperature distribution

    International Nuclear Information System (INIS)

    Buyadi, S N A; Mohd, W M N W; Misni, A

    2014-01-01

    Earlier studies have indicated that, the temperature distribution in the urban area is significantly warmer than its surrounding suburban areas. The process of urbanization has created urban heat island (UHI). As a city expands, trees are cut down to accommodate commercial development, industrial areas, roads, and suburban growth. Trees or green areas normally play a vital role in mitigating the UHI effects especially in regulating high temperature in saturated urban areas. This study attempts to assess the effects of vegetation growth on land surface temperature (LST) distribution in urban areas. An area within the City of Shah Alam, Selangor has been selected as the study area. Land use/land cover and LST maps of two different dates are generated from Landsat 5 TM images of the year 1991 and 2009. Only five major land cover classes are considered in this study. Mono-window algorithm is used to generate the LST maps. Landsat 5 TM images are also used to generate the NDVI maps. Results from this study have shown that there are significant land use changes within the study area. Although the conversion of green areas into residential and commercial areas significantly increase the LST, matured trees will help to mitigate the effects of UHI

  15. Electronic structure, molecular bonding and potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ruedenberg, K. [Ames Laboratory, IA (United States)

    1993-12-01

    By virtue of the universal validity of the generalized Born-Oppenheimer separation, potential energy surfaces (PES`) represent the central conceptual as well as quantitative entities of chemical physics and provide the basis for the understanding of most physicochemical phenomena in many diverse fields. The research in this group deals with the elucidation of general properties of PES` as well as with the quantitative determination of PES` for concrete systems, in particular pertaining to reactions involving carbon, oxygen, nitrogen and hydrogen molecules.

  16. Phonon Surface Scattering and Thermal Energy Distribution in Superlattices.

    Science.gov (United States)

    Kothari, Kartik; Maldovan, Martin

    2017-07-17

    Thermal transport at small length scales has attracted significant attention in recent years and various experimental and theoretical methods have been developed to establish the reduced thermal conductivity. The fundamental understanding of how phonons move and the physical mechanisms behind nanoscale thermal transport, however, remains poorly understood. Here we move beyond thermal conductivity calculations and provide a rigorous and comprehensive physical description of thermal phonon transport in superlattices by solving the Boltzmann transport equation and using the Beckman-Kirchhoff surface scattering theory with shadowing to precisely describe phonon-surface interactions. We show that thermal transport in superlattices can be divided in two different heat transport modes having different physical properties at small length scales: layer-restricted and extended heat modes. We study how interface conditions, periodicity, and composition can be used to manipulate the distribution of thermal energy flow among such layer-restricted and extended heat modes. From predicted frequency and mean free path spectra of superlattices, we also investigate the existence of wave effects. The results and insights in this paper advance the fundamental understanding of heat transport in superlattices and the prospects of rationally designing thermal systems with tailored phonon transport properties.

  17. Surface deformation during an action potential in pearled cells

    Science.gov (United States)

    Mussel, Matan; Fillafer, Christian; Ben-Porath, Gal; Schneider, Matthias F.

    2017-11-01

    Electric pulses in biological cells (action potentials) have been reported to be accompanied by a propagating cell-surface deformation with a nanoscale amplitude. Typically, this cell surface is covered by external layers of polymer material (extracellular matrix, cell wall material, etc.). It was recently demonstrated in excitable plant cells (Chara braunii) that the rigid external layer (cell wall) hinders the underlying deformation. When the cell membrane was separated from the cell wall by osmosis, a mechanical deformation, in the micrometer range, was observed upon excitation of the cell. The underlying mechanism of this mechanical pulse has, to date, remained elusive. Herein we report that Chara cells can undergo a pearling instability, and when the pearled fragments were excited even larger and more regular cell shape changes were observed (˜10 -100 μ m in amplitude). These transient cellular deformations were captured by a curvature model that is based on three parameters: surface tension, bending rigidity, and pressure difference across the surface. In this paper these parameters are extracted by curve-fitting to the experimental cellular shapes at rest and during excitation. This is a necessary step to identify the mechanical parameters that change during an action potential.

  18. Wright Valley Sediments as Potential Analogs for Martian Surface Processes

    Science.gov (United States)

    Englert, P. A. J.; Bishop, J. L.; Patel, S.; Gibson, E. K.; Koeberl, C.

    2015-12-01

    The Antarctic Dry Valleys (ADV) may provide a unique terrestrial analog for current Martian surface processes. The Wright Valley located in the ADV contains streams, lakes and ponds that host highly saline, sedimentary environments. This project highlights comparisons of formation and salt accumulation processes at the Don Juan Pond (DJP) and Don Quixote Pond (DQP). These are located in the north and south forks of the Wright Valley, which are unique areas where unusual terrestrial processes can be studied. DQP is located in the western part of the north fork about 100 m above mean seawater level. The DQP Valley walls are up to 2500 m high and the brine is seasonally frozen. DJP from the south fork is located ~9 km west of Lake Vanda. The basin floor is 117 m above mean seawater level with activity to the north and south rising above 1000 m. The DJP brine does not freeze and may be a model environment for Ca and Cl weathering and distribution on Mars. Our findings indicate that DJP and DQP have formed in similar climatic and geological environments, but likely experienced different formation conditions. Samples were collected from surface, soil pits and depth profiles during the 1979/1980, the 1990/1991 and the 2005/2006 field seasons. Elemental abundances and mineralogy were evaluated for several sets of sediments. The DJP basin shows low surface abundances of halite and relatively high abundances of sulfates throughout with gypsum or anhydrite dominating at different locations. The DQP area has high surface abundances of halite with gypsum present as the major sulfate. Two models have been proposed to explain these differences: DQP may have formed through a combination of shallow and some deep groundwater influx, while deep groundwater upwelling likely played the dominant role of salt formation at DJP. Our study seeks to understand the formation of DQP and DJP as unique terrestrial processes and as models for Ca, Cl, and S weathering and distribution on Mars.

  19. Theoretical studies of potential energy surfaces and computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, R. [Argonne National Laboratory, IL (United States)

    1993-12-01

    This project involves the development, implementation, and application of theoretical methods for the calculation and characterization of potential energy surfaces involving molecular species that occur in hydrocarbon combustion. These potential energy surfaces require an accurate and balanced treatment of reactants, intermediates, and products. This difficult challenge is met with general multiconfiguration self-consistent-field (MCSCF) and multireference single- and double-excitation configuration interaction (MRSDCI) methods. In contrast to the more common single-reference electronic structure methods, this approach is capable of describing accurately molecular systems that are highly distorted away from their equilibrium geometries, including reactant, fragment, and transition-state geometries, and of describing regions of the potential surface that are associated with electronic wave functions of widely varying nature. The MCSCF reference wave functions are designed to be sufficiently flexible to describe qualitatively the changes in the electronic structure over the broad range of geometries of interest. The necessary mixing of ionic, covalent, and Rydberg contributions, along with the appropriate treatment of the different electron-spin components (e.g. closed shell, high-spin open-shell, low-spin open shell, radical, diradical, etc.) of the wave functions, are treated correctly at this level. Further treatment of electron correlation effects is included using large scale multireference CI wave functions, particularly including the single and double excitations relative to the MCSCF reference space. This leads to the most flexible and accurate large-scale MRSDCI wave functions that have been used to date in global PES studies.

  20. Calibration of a distributed hydrological model using satellite data of land surface temperature

    Science.gov (United States)

    Corbari, Chiara; Mancini, Marco; Ravazzani, Giovanni

    2013-04-01

    Calibration and validation of distributed models at basin scale generally refer to external variables, which are integrated catchment model outputs, and usually depend on the comparison between simulated and observed discharges at the available rivers cross sections, which are usually very few. However distributed models allow an internal validation due to their intrinsic structure, so that internal processes and variables of the model can be controlled in each cell of the domain. In particular this work investigates the potentiality to control evapotranspiration and its spatial and temporal variability through the detection of land surface temperature (LST) from satellite remote sensing. This study proposes a methodology for the calibration of distributed hydrological models at basin scale using remote sensing data of land surface temperature. The distributed energy water balance model, Flash-flood Event-based Spatially-distributed rainfall-runoff Transformation - Energy Water Balance model (FEST-EWB) will be calibrated in the Upper Po river basin (Italy) closed at the river cross section of Ponte della Becca with a total catchment area of about 38000 km2. The model algorithm solves the system of energy and mass balances in term of the representative pixel equilibrium temperature (RET) that governs the fluxes of energy and mass over the basin domain. This equilibrium surface temperature, which is a critical model state variable, is comparable to the land surface temperature (LST) from satellite. So a pixel to pixel semi-automatic calibration procedure of soil and vegetation parameter is presented through the comparison between the model internal state variable RET and the remotely observed LST. A similar calibration procedure will also be applied performing the traditional calibration using only discharge measurements. 260 diurnal and nocturne LST MODIS products are compared with FEST-EWB land surface temperature over the 11 years of simulation from 2000 to 2010

  1. In vitro studies on the cytotoxic potential of surface sealants.

    Science.gov (United States)

    Zingler, S; Matthei, B; Kohl, A; Saure, D; Ludwig, B; Diercke, K; Lux, C J; Erber, R

    2015-01-01

    The objective of this in vitro study was an initial screening of the cytotoxic potential of widely used smooth enamel surface sealants. A total of 20 products were allocated to four groups based on their chemical composition: (1) filled resin-based sealants, (2) unfilled resin-based sealants, (3) a resin-modified, glass ionomer-based sealant, and (4) silicone-based sealants. All materials were applied to human enamel slices both in accordance with manufacturers' instructions and in additional experiments applying 50% undercuring and 50% overcuring. An agar overlay assay was then used to test the specimens following ISO 10933. The cytotoxic potential of each material was interpreted based on a reaction index that summarized the decolorization and lysis scores obtained. The cytotoxic potential decreased as follows: unfilled resin-based sealants > filled resin-based sealants > resin-modified, glass ionomer-based sealant > silicone-based sealants. In 75% of the resin-based products, deliberate undercuring was associated with more extensive decolorization zones, leading to higher rates of cytotoxic potential in two of those products. Overcuring, by contrast, was associated with a tendency for smaller decolorization zones in 50% of the resin-based products. Surface sealants derived from resin monomers exhibited cytotoxic potential in the agar overlay assay. There is also evidence of a possible association with curing, as undercuring can increase the cytotoxic potential, whereas normal curing (as per manufacturers' instructions) or overcuring may help minimize such effects. More research into the biological implications of these materials is needed, especially with regard to their potential impact on the adjacent gingiva.

  2. Spatial distributions of Southern Ocean mesozooplankton communities have been resilient to long-term surface warming.

    Science.gov (United States)

    Tarling, Geraint A; Ward, Peter; Thorpe, Sally E

    2018-01-01

    The biogeographic response of oceanic planktonic communities to climatic change has a large influence on the future stability of marine food webs and the functioning of global biogeochemical cycles. Temperature plays a pivotal role in determining the distribution of these communities and ocean warming has the potential to cause major distributional shifts, particularly in polar regions where the thermal envelope is narrow. We considered the impact of long-term ocean warming on the spatial distribution of Southern Ocean mesozooplankton communities through examining plankton abundance in relation to sea surface temperature between two distinct periods, separated by around 60 years. Analyses considered 16 dominant mesozooplankton taxa (in terms of biomass and abundance) in the southwest Atlantic sector of the Southern Ocean, from net samples and in situ temperature records collected during the Discovery Investigations (1926-1938) and contemporary campaigns (1996-2013). Sea surface temperature was found to have increased significantly by 0.74°C between the two eras. The corresponding sea surface temperature at which community abundance peaked was also significantly higher in contemporary times, by 0.98°C. Spatial projections indicated that the geographical location of community peak abundance had remained the same between the two eras despite the poleward advance of sea surface isotherms. If the community had remained within the same thermal envelope as in the 1920s-1930s, community peak abundance would be 500 km further south in the contemporary era. Studies in the northern hemisphere have found that dominant taxa, such as calanoid copepods, have conserved their thermal niches and tracked surface isotherms polewards. The fact that this has not occurred in the Southern Ocean suggests that other selective pressures, particularly food availability and the properties of underlying water masses, place greater constraints on spatial distributions in this region. It

  3. Simulation of a Lunar Surface Base Power Distribution Network for the Constellation Lunar Surface Systems

    Science.gov (United States)

    Mintz, Toby; Maslowski, Edward A.; Colozza, Anthony; McFarland, Willard; Prokopius, Kevin P.; George, Patrick J.; Hussey, Sam W.

    2010-01-01

    The Lunar Surface Power Distribution Network Study team worked to define, breadboard, build and test an electrical power distribution system consistent with NASA's goal of providing electrical power to sustain life and power equipment used to explore the lunar surface. A testbed was set up to simulate the connection of different power sources and loads together to form a mini-grid and gain an understanding of how the power systems would interact. Within the power distribution scheme, each power source contributes to the grid in an independent manner without communication among the power sources and without a master-slave scenario. The grid consisted of four separate power sources and the accompanying power conditioning equipment. Overall system design and testing was performed. The tests were performed to observe the output and interaction of the different power sources as some sources are added and others are removed from the grid connection. The loads on the system were also varied from no load to maximum load to observe the power source interactions.

  4. Modeling global distribution of agricultural insecticides in surface waters.

    Science.gov (United States)

    Ippolito, Alessio; Kattwinkel, Mira; Rasmussen, Jes J; Schäfer, Ralf B; Fornaroli, Riccardo; Liess, Matthias

    2015-03-01

    Agricultural insecticides constitute a major driver of animal biodiversity loss in freshwater ecosystems. However, the global extent of their effects and the spatial extent of exposure remain largely unknown. We applied a spatially explicit model to estimate the potential for agricultural insecticide runoff into streams. Water bodies within 40% of the global land surface were at risk of insecticide runoff. We separated the influence of natural factors and variables under human control determining insecticide runoff. In the northern hemisphere, insecticide runoff presented a latitudinal gradient mainly driven by insecticide application rate; in the southern hemisphere, a combination of daily rainfall intensity, terrain slope, agricultural intensity and insecticide application rate determined the process. The model predicted the upper limit of observed insecticide exposure measured in water bodies (n = 82) in five different countries reasonably well. The study provides a global map of hotspots for insecticide contamination guiding future freshwater management and conservation efforts. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Pore scale heterogeneity in the mineral distribution and surface area of porous rocks

    Science.gov (United States)

    Lai, Peter; Moulton, Kevin; Krevor, Samuel

    2014-05-01

    There are long-standing challenges in characterizing reactive transport in porous media at scales larger than individual pores. This hampers the prediction of the field-scale impact of geochemical processes on fluid flow [1]. This is a source of uncertainty for carbon dioxide injection, which results in a reactive fluid-rock system, particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2,3]. The objective of this study was to quantify heterogeneity in reactive surface and observe the extent of its non-normal character. In this study we describe our work in using micron-scale x-ray imaging and other spectroscopic techniques for the purpose of describing the statistical distribution of reactive surface area within a porous medium, and identifying specific mineral phases and their distribution in 3-dimensions. Using in-house image processing techniques and auxilary charactersation with thin section, electron microscope and spectroscopic techniques we quantified the surface area of each mineral phase in the x-ray CT images. This quantification was validated against nitrogen BET surface area and backscattered electron imaging measurements of the CT-imaged samples. Distributions in reactive surface area for each mineral phase were constructed by calculating surface areas in thousands of randomly selected subvolume images of the total sample, each normalized to the pore volume in that image. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be

  6. Intrinsic Charge Trapping Observed as Surface Potential Variations in diF-TES-ADT Films.

    Science.gov (United States)

    Hoffman, Benjamin C; McAfee, Terry; Conrad, Brad R; Loth, Marsha A; Anthony, John E; Ade, Harald W; Dougherty, Daniel B

    2016-08-24

    Spatial variations in surface potential are measured with Kelvin probe force microscopy for thin films of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophenes (diF-TES-ADT) grown on SiO2 and silane-treated SiO2 substrates by organic molecular beam deposition. The variations are observed both between and within grains of the polycrystalline organic film and are quantitatively different than electrostatic variations on the substrate surfaces. The skewness of surface potential distributions is larger on SiO2 than on HMDS-treated substrates. This observation is attributed to the impact of substrate functionalization on minimizing intrinsic crystallographic defects in the organic film that can trap charge.

  7. AFM-assisted fabrication of thiol SAM pattern with alternating quantified surface potential

    Directory of Open Access Journals (Sweden)

    Simons Janet

    2011-01-01

    Full Text Available Abstract Thiol self-assembled monolayers (SAMs are widely used in many nano- and bio-technology applications. We report a new approach to create and characterize a thiol SAMs micropattern with alternating charges on a flat gold-coated substrate using atomic force microscopy (AFM and Kelvin probe force microscopy (KPFM. We produced SAMs-patterns made of alternating positively charged, negatively charged, and hydrophobic-terminated thiols by an automated AFM-assisted manipulation, or nanografting. We show that these thiol patterns possess only small topographical differences as revealed by AFM, and distinguished differences in surface potential (20-50 mV, revealed by KPFM. The pattern can be helpful in the development of biosensor technologies, specifically for selective binding of biomolecules based on charge and hydrophobicity, and serve as a model for creating surfaces with quantified alternating surface potential distribution.

  8. Exploring the potential uptake of distributed energy generation

    International Nuclear Information System (INIS)

    Gardner, John; Ashworth, Peta; Carr-Cornish, Simone

    2007-01-01

    Full text: Global warming has been identified as an energy problem (Klare 2007). With a predicted increase in fossil fuel use for many years to come (IEA 2004) there is a need to find a future energy path that will meet our basic requirements for energy but also help to mitigate climate change (CSIRO 2006). Currently there are a range of technological solutions available, with each representing a different value proposition. Distributed Energy (DE) is one such technological solution, which involves the widespread use of small local power generators, located close to the end user. Such generators can be powered by a range of low emission and/or renewable sources. Until now, cheap electricity, existing infrastructure and reluctance for change both at a political and individual level has meant there has been little prospect for DE to be considered in Australia, except in some remote communities. However, with the majority of Australians now rating climate change as an issue of strategic importance to Australia (Ashworth, Pisarski and Littleboy 2006), it can be inferred that Australia's tolerance for generating greenhouse gas emissions has reduced, and that potential support for DE is increasing. It is therefore important to understand what factors might influence the potential adoption of DE. As part of a research project called the Intelligent Grid, CSIRO's Energy Transformed Flagship is aiming to identify the conditions under which Distributed Energy might be effectively implemented in Australia. One component of this project involves social research, which aims to understand the drivers and barriers to the uptake of DE technology by the community. This paper presents findings from two large-scale surveys (one of householders and one of businesses), designed to assess beliefs and knowledge about environmental issues, and about traditional and renewable energy sources. The surveys also assess current energy use, and identify preferences regarding DE technology. The

  9. Measuring surface flow velocity with smartphones: potential for citizen observatories

    Science.gov (United States)

    Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik

    2014-05-01

    Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.

  10. Mesogranulation and the Solar Surface Magnetic Field Distribution

    Science.gov (United States)

    Yelles Chaouche, L.; Moreno-Insertis, F.; Martínez Pillet, V.; Wiegelmann, T.; Bonet, J. A.; Knölker, M.; Bellot Rubio, L. R.; del Toro Iniesta, J. C.; Barthol, P.; Gandorfer, A.; Schmidt, W.; Solanki, S. K.

    2011-02-01

    The relation of the solar surface magnetic field with mesogranular cells is studied using high spatial (≈100 km) and temporal (≈30 s) resolution data obtained with the IMaX instrument on board SUNRISE. First, mesogranular cells are identified using Lagrange tracers (corks) based on horizontal velocity fields obtained through local correlation tracking. After ≈20 minutes of integration, the tracers delineate a sharp mesogranular network with lanes of width below about 280 km. The preferential location of magnetic elements in mesogranular cells is tested quantitatively. Roughly 85% of pixels with magnetic field higher than 100 G are located in the near neighborhood of mesogranular lanes. Magnetic flux is therefore concentrated in mesogranular lanes rather than intergranular ones. Second, magnetic field extrapolations are performed to obtain field lines anchored in the observed flux elements. This analysis, therefore, is independent of the horizontal flows determined in the first part. A probability density function (PDF) is calculated for the distribution of distances between the footpoints of individual magnetic field lines. The PDF has an exponential shape at scales between 1 and 10 Mm, with a constant characteristic decay distance, indicating the absence of preferred convection scales in the mesogranular range. Our results support the view that mesogranulation is not an intrinsic convective scale (in the sense that it is not a primary energy-injection scale of solar convection), but also give quantitative confirmation that, nevertheless, the magnetic elements are preferentially found along mesogranular lanes.

  11. Present and potential distribution of Snub-nosed Monkey

    DEFF Research Database (Denmark)

    Nüchel, Jonas; Bøcher, Peder Klith; Svenning, Jens-Christian

    are the Snub-nosed Monkeys (Rhinopithecus), a temperate-subtropical East Asian genus. We use species distribution modeling to assess the following question of key relevancy for conservation management of Rhinopithecus; 1. Which climatic factors determine the present distribution of Rhinopithecus within...... distribution of Rhinopithecus within the region, considering climate, habitat availability and the locations of nature reserves. Keywords: biodiversity, biogeography, conservation, China, snub-nosed monkey, rhinopithecus, primates, species distribution modeling...

  12. Pseudospectral Gaussian quantum dynamics: Efficient sampling of potential energy surfaces.

    Science.gov (United States)

    Heaps, Charles W; Mazziotti, David A

    2016-04-28

    Trajectory-based Gaussian basis sets have been tremendously successful in describing high-dimensional quantum molecular dynamics. In this paper, we introduce a pseudospectral Gaussian-based method that achieves accurate quantum dynamics using efficient, real-space sampling of the time-dependent basis set. As in other Gaussian basis methods, we begin with a basis set expansion using time-dependent Gaussian basis functions guided by classical mechanics. Unlike other Gaussian methods but characteristic of the pseudospectral and collocation methods, the basis set is tested with N Dirac delta functions, where N is the number of basis functions, rather than using the basis function as test functions. As a result, the integration for matrix elements is reduced to function evaluation. Pseudospectral Gaussian dynamics only requires O(N) potential energy calculations, in contrast to O(N(2)) evaluations in a variational calculation. The classical trajectories allow small basis sets to sample high-dimensional potentials. Applications are made to diatomic oscillations in a Morse potential and a generalized version of the Henon-Heiles potential in two, four, and six dimensions. Comparisons are drawn to full analytical evaluation of potential energy integrals (variational) and the bra-ket averaged Taylor (BAT) expansion, an O(N) approximation used in Gaussian-based dynamics. In all cases, the pseudospectral Gaussian method is competitive with full variational calculations that require a global, analytical, and integrable potential energy surface. Additionally, the BAT breaks down when quantum mechanical coherence is particularly strong (i.e., barrier reflection in the Morse oscillator). The ability to obtain variational accuracy using only the potential energy at discrete points makes the pseudospectral Gaussian method a promising avenue for on-the-fly dynamics, where electronic structure calculations become computationally significant.

  13. Changes of Surface Electric Potential of Bones Depending on Their Age

    OpenAIRE

    Freimanis, E; Dehtjars, J; Vendiņa, V

    2014-01-01

    The aim of this research was to determine how surface electric potential of bones changes with their age and how it correlates with mechanical properties of bones. Surface electric potential was measured in 6 cross-sectional zones of the tibia. Changes of bones surface electric potential with age were determined and correlations between surface electric potential and mechanical properties were derived.

  14. Forces on nuclei moving on autoionizing molecular potential energy surfaces.

    Science.gov (United States)

    Moiseyev, Nimrod

    2017-01-14

    Autoionization of molecular systems occurs in diatomic molecules and in small biochemical systems. Quantum chemistry packages enable calculation of complex potential energy surfaces (CPESs). The imaginary part of the CPES is associated with the autoionization decay rate, which is a function of the molecular structure. Molecular dynamics simulations, within the framework of the Born-Oppenheimer approximation, require the definition of a force field. The ability to calculate the forces on the nuclei in bio-systems when autoionization takes place seems to rely on an understanding of radiative damages in RNA and DNA arising from the release of slow moving electrons which have long de Broglie wavelengths. This work addresses calculation of the real forces on the nuclei moving on the CPES. By using the transformation of the time-dependent Schrödinger equation, previously used by Madelung, we proved that the classical forces on nuclei moving on the CPES correlated with the gradient of the real part of the CPES. It was proved that the force on the nuclei of the metastable molecules is time independent although the probability to detect metastable molecules exponentially decays. The classical force is obtained from the transformed Schrödinger equation when ℏ=0 and the Schrödinger equation is reduced to the classical (Newtonian) equations of motion. The forces on the nuclei regardless on what potential energy surface they move (parent CPES or product real PESs) vary in time due to the autoionization process.

  15. Erosive potential of energy drinks on the dentine surface.

    Science.gov (United States)

    Pinto, Shelon C S; Bandeca, Matheus C; Silva, Carolina N; Cavassim, Rodrigo; Borges, Alvaro H; Sampaio, José E C

    2013-02-19

    Considering the current high consumption of energy drinks, the aim of the present study is to evaluate the influence of energy drinks in removing the smear layer and exposing dentinal tubules on root surface. Dentine root surfaces were exposed using a diamond bur. Forty movements of scaling were performed in the area prepared in order to create a smear layer. One hundred and thirty specimens were obtained from 35 teeth. Specimens were randomly distributed into 12 groups (n = 10) and divided into subgroups according to the application: topical (n = 5) and friction (n = 5). Twelve energy drinks were evaluated: RedBull, Burn, TNT, Flash Power, Flying Horse, Sports Drink, Ionic, Hot Power, Army Power, Gladiator and Bug. Distilled water was used as a control group. The specimens were analysed by scanning electron microscopy. Topical application: a significant influence of energy drinks on smear layer removal was found for FlyingHorse and Bug when compared with the control group. Friction application: significant smear layer removal was found for Burn, FlyingHorse, Gladiator, SportsDrinks, when compared with the control group. Comparing the different application forms, a statistically significant difference was found for Army Power. Considering the significant smear layer removal, energy drinks can be an important etiological factor for cervical dentine hypersensitivity.

  16. DISTRIBUTED EXTERNAL SURFACE HARDENING OF CAR DESIGN BY WINDING

    Directory of Open Access Journals (Sweden)

    O. V. Fomin

    2017-04-01

    Full Text Available Purpose. The paper involves coverage of features and results of the research conducted by the authors to determine the feasibility and establishment of pre-stressed-strained state of freight cars by winding in order to improve their strength characteristics. It is also necessary to present the theoretical justification for the effectiveness of the application of this method for car designs and an appropriate example for the tank-car. Methodology. The conducted study is based on an analysis of known works on the subject, mathematical justification and computer modeling. At the calculations of rolling stock components contemporary conventional techniques were used. Findings. Authors found that the winding method for pre-stressed-strained state is effective and appropriate for use in the construction of railway rolling stock and, in particular freight cars. Freight car designs with the pre-stressed-strained state are characterized by a number of strength advantages, among which there is an improvement of the work on the perception of operational loads and resource conservation. Originality. For the first time it is proposed the improvement of bearing capacity of freight car constructions through the creation of its component in the directed stress-strained state. It is also for the first time proposed the use of distributed external surface hardening by the method of winding to create a pre-stress-strained state of structural components of freight cars. The methods for winding designs of freight cars and their implementation were considered. Practical value. The studies developed a number of technical solutions for improving the design of freight cars and tank-container, which has been patented. Corresponding solutions for the tank-car are partially presented. Practical implementation of such solutions will significantly improve the technical, economic and operational performances of car designs.

  17. Landscape structure affects distribution of potential disease vectors (Diptera: Culicidae).

    Science.gov (United States)

    Zittra, Carina; Vitecek, Simon; Obwaller, Adelheid G; Rossiter, Heidemarie; Eigner, Barbara; Zechmeister, Thomas; Waringer, Johann; Fuehrer, Hans-Peter

    2017-04-26

    Vector-pathogen dynamics are controlled by fluctuations of potential vector communities, such as the Culicidae. Assessment of mosquito community diversity and, in particular, identification of environmental parameters shaping these communities is therefore of key importance for the design of adequate surveillance approaches. In this study, we assess effects of climatic parameters and habitat structure on mosquito communities in eastern Austria to deliver these highly relevant baseline data. Female mosquitoes were sampled twice a month from April to October 2014 and 2015 at 35 permanent and 23 non-permanent trapping sites using carbon dioxide-baited traps. Differences in spatial and seasonal abundance patterns of Culicidae taxa were identified using likelihood ratio tests; possible effects of environmental parameters on seasonal and spatial mosquito distribution were analysed using multivariate statistical methods. We assessed community responses to environmental parameters based on 14-day-average values that affect ontogenesis. Altogether 29,734 female mosquitoes were collected, and 21 of 42 native as well as two of four non-native mosquito species were reconfirmed in eastern Austria. Statistical analyses revealed significant differences in mosquito abundance between sampling years and provinces. Incidence and abundance patterns were found to be linked to 14-day mean sunshine duration, humidity, water-level maxima and the amount of precipitation. However, land cover classes were found to be the most important factor, effectively assigning both indigenous and non-native mosquito species to various communities, which responded differentially to environmental variables. These findings thus underline the significance of non-climatic variables for future mosquito prediction models and the necessity to consider these in mosquito surveillance programmes.

  18. Distributed Generation potential of the U.S. commercial sector

    International Nuclear Information System (INIS)

    Hamachi LaCommare, Kristina; Edwards, Jennifer L.; Gumerman, Etan; Marnay, Chris

    2005-01-01

    Small-scale (100 kW - 5 MW) on-site distributed generation (DG) economically driven by combined heat and power (CHP) applications and, in some cases, reliability concerns will likely emerge as a common feature of commercial building energy systems in developed countries over the next two decades. In the U.S., private and public expectations for this technology are heavily influenced by forecasts published by the Energy Information Administration (EIA), most notably the Annual Energy Outlook (AEO). EIA's forecasts are typically made using the National Energy Modeling System (NEMS), which has a forecasting module that predicts the penetration of several possible commercial building DG technologies over the period 2005-2025. Annual penetration is forecast by estimating the payback period for each technology, for each of a limited number of representative building types, for each of nine regions. This process results in an AEO2004 forecast deployment of about a total 3 GW of DG electrical generating capacity by 2025, which is only 0.25% of total forecast U.S. capacity. Analyses conducted using both the AEO2003 and AEO2004 versions of NEMS changes the baseline costs and performance characteristics of DG to reflect a world without U.S. Dept. of Energy (DOE) research into several thermal DG technologies, which is then compared to a case with enhanced technology representative of the successful achievement of DOE research goals. The net difference in 2025 DG penetration is dramatic using the AEO2003 version of NEMS, but much smaller in the AEO2004 version. The significance and validity of these contradictory results are discussed, and possibilities for improving estimates of commercial U.S. DG potential are explored

  19. Surface-wave potential for triggering tectonic (nonvolcanic) tremor

    Science.gov (United States)

    Hill, D.P.

    2010-01-01

    Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle is anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45?? incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia mega-thrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction, ????? 0.2). However, documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, is associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (?? ~ 0.6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.

  20. Controlling charges distribution at the surface of a single GaN nanowire by in-situ strain

    Directory of Open Access Journals (Sweden)

    Xiao Chen

    2017-08-01

    Full Text Available Effect of the strain on the charge distribution at the surface of a GaN semiconductor nanowire (NW has been investigated inside transmission electron microscope (TEM by in-situ off-axis electron holography. The outer and inner surfaces of the NW bent axially under compression of two Au electrodes were differently strained, resulting in difference of their Fermi levels. Consequently, the free electrons flow from the high Fermi level to the low level until the two Fermi levels aligned in a line. The potential distributions induced by charge redistribution in the two vacuum sides of the bent NW were examined respectively, and the opposite nature of the bounded charges on the outer and inner surfaces of the bent NW was identified. The results provide experimental evidence that the charge distribution at the surfaces of a single GaN NW can be controlled by different strains created along the NW.

  1. Pore scale heterogeneity in the mineral distribution and reactive surface area of rocks

    Science.gov (United States)

    Lai, P. E.; Krevor, S. C.

    2013-12-01

    There are long-standing challenges in characterizing reactive transport in porous media at scales larger than individual pores. This hampers the prediction of the field-scale impact of geochemical processes on fluid flow [1]. This is a source of uncertainty for CO2 injection, which results in a reactive fluid-rock system, particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2,3]. In this study we have created μm resolution 3D images of 3 sandstone and 4 carbonate rocks using x-ray microtomography. Using in-house image processing techniques and auxiliary characterisation with thin section, electron microscope and spectroscopic techniques we quantified the surface area of each mineral phase in the x-ray CT images. This quantification was validated against N2 BET surface area and He porosity measurements of the imaged samples. Distributions in reactive surface area for each mineral phase were constructed by calculating surface areas in thousands of randomly selected subvolume images of the total sample, each normalized to the pore volume in that image. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be characterized at multiple length scales for an accurate description of reactive transport. [1] Maher, Steefel, Depaolo and Vianni (2006) Geochimica et Cosmochimica Acta, 70, 337-363 [2] Landrot, Ajo-Franklin, Yang, Cabrini and Steefel (2012) Chemical Geology 318-319, 113-125 [3] Li, Peters and Celia (2007) American Journal of Science 307, 1146

  2. CO dimer: new potential energy surface and rovibrational calculations.

    Science.gov (United States)

    Dawes, Richard; Wang, Xiao-Gang; Carrington, Tucker

    2013-08-15

    The spectrum of CO dimer was investigated by solving the rovibrational Schrödinger equation on a new potential energy surface constructed from coupled-cluster ab initio points. The Schrödinger equation was solved with a Lanczos algorithm. Several 4D (rigid monomer) global ab initio potential energy surfaces (PESs) were made using a previously reported interpolating moving least-squares (IMLS) fitting procedure specialized to describe the interaction of two linear fragments. The potential has two nonpolar minima giving rise to a complicated set of energy level stacks, which are very sensitive to the shapes and relative depths of the two wells. Although the CO dimer has defied previous attempts at an accurate purely ab initio description our best surface yields results in good agreement with experiment. Root-mean-square (rms) fitting errors of less than 0.1 cm(-1) were obtained for each of the fits using 2226 ab initio data at different levels. This allowed direct assessment of the quality of various levels of ab initio theory for prediction of spectra. Our tests indicate that standard CCSD(T) is slow to converge the interaction energy even when sextuple zeta bases as large as ACV6Z are used. The explicitly correlated CCSD(T)-F12b method was found to recover significantly more correlation energy (from singles and doubles) at the CBS limit. Correlation of the core-electrons was found to be important for this system. The best PES was obtained by extrapolation of calculations at the CCSD(T)(AE)-F12b/CVnZ-F12 (n = 3,4) levels. The calculated energy levels were compared to 105 J ≤ 10 levels from experiment. The rms error for 68 levels with J ≤ 6 is only 0.29 cm(-1). The calculated energy levels were assigned stack labels using several tools. New stacks were found. One of them, stack y1, has an energy lower than many previously known stacks and may be observable.

  3. Stabilized quasi-Newton optimization of noisy potential energy surfaces

    International Nuclear Information System (INIS)

    Schaefer, Bastian; Goedecker, Stefan; Alireza Ghasemi, S.; Roy, Shantanu

    2015-01-01

    Optimizations of atomic positions belong to the most commonly performed tasks in electronic structure calculations. Many simulations like global minimum searches or characterizations of chemical reactions require performing hundreds or thousands of minimizations or saddle computations. To automatize these tasks, optimization algorithms must not only be efficient but also very reliable. Unfortunately, computational noise in forces and energies is inherent to electronic structure codes. This computational noise poses a severe problem to the stability of efficient optimization methods like the limited-memory Broyden–Fletcher–Goldfarb–Shanno algorithm. We here present a technique that allows obtaining significant curvature information of noisy potential energy surfaces. We use this technique to construct both, a stabilized quasi-Newton minimization method and a stabilized quasi-Newton saddle finding approach. We demonstrate with the help of benchmarks that both the minimizer and the saddle finding approach are superior to comparable existing methods

  4. Exploring Multiple Potential Energy Surfaces: Photochemistry of Small Carbonyl Compounds

    Directory of Open Access Journals (Sweden)

    Satoshi Maeda

    2012-01-01

    Full Text Available In theoretical studies of chemical reactions involving multiple potential energy surfaces (PESs such as photochemical reactions, seams of intersection among the PESs often complicate the analysis. In this paper, we review our recipe for exploring multiple PESs by using an automated reaction path search method which has previously been applied to single PESs. Although any such methods for single PESs can be employed in the recipe, the global reaction route mapping (GRRM method was employed in this study. By combining GRRM with the proposed recipe, all critical regions, that is, transition states, conical intersections, intersection seams, and local minima, associated with multiple PESs, can be explored automatically. As illustrative examples, applications to photochemistry of formaldehyde and acetone are described. In these examples as well as in recent applications to other systems, the present approach led to discovery of many unexpected nonadiabatic pathways, by which some complicated experimental data have been explained very clearly.

  5. Improved DFT Potential Energy Surfaces via Improved Densities.

    Science.gov (United States)

    Kim, Min-Cheol; Park, Hansol; Son, Suyeon; Sim, Eunji; Burke, Kieron

    2015-10-01

    Density-corrected DFT is a method that cures several failures of self-consistent semilocal DFT calculations by using a more accurate density instead. A novel procedure employs the Hartree-Fock density to bonds that are more severely stretched than ever before. This substantially increases the range of accurate potential energy surfaces obtainable from semilocal DFT for many heteronuclear molecules. We show that this works for both neutral and charged molecules. We explain why and explore more difficult cases, for example, CH(+), where density-corrected DFT results are even better than sophisticated methods like CCSD. We give a simple criterion for when DC-DFT should be more accurate than self-consistent DFT that can be applied for most cases.

  6. Concentration distributions of thoron and radon near the ground surface

    Energy Technology Data Exchange (ETDEWEB)

    Katase, Akira [Tohwa Univ., Fukuoka (Japan). Faculty of Engineering

    1996-12-01

    One dimensional diffusion model with a constant diffusion coefficient is applied to the thoron concentration distributions in air above the ground. The experimental distributions are well described by the exponential function obtained from the model. Diffusion coefficients and thoron exhalation rates are estimated from the measured distributions, which are the average values for three months. The present values of thoron exhalation are however several times as small as those measured by other researchers. (author)

  7. Distribution of near-surface permafrost in Alaska: estimates of present and future conditions

    Science.gov (United States)

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Nield, Shawn J.; Johnson, Kristofer D.; Finley, Andrew O.

    2015-01-01

    High-latitude regions are experiencing rapid and extensive changes in ecosystem composition and function as the result of increases in average air temperature. Increasing air temperatures have led to widespread thawing and degradation of permafrost, which in turn has affected ecosystems, socioeconomics, and the carbon cycle of high latitudes. Here we overcome complex interactions among surface and subsurface conditions to map nearsurface permafrost through decision and regression tree approaches that statistically and spatially extend field observations using remotely sensed imagery, climatic data, and thematic maps of a wide range of surface and subsurface biophysical characteristics. The data fusion approach generated medium-resolution (30-m pixels) maps of near-surface (within 1 m) permafrost, active-layer thickness, and associated uncertainty estimates throughout mainland Alaska. Our calibrated models (overall test accuracy of ~85%) were used to quantify changes in permafrost distribution under varying future climate scenarios assuming no other changes in biophysical factors. Models indicate that near-surface permafrost underlies 38% of mainland Alaska and that near-surface permafrost will disappear on 16 to 24% of the landscape by the end of the 21st Century. Simulations suggest that near-surface permafrost degradation is more probable in central regions of Alaska than more northerly regions. Taken together, these results have obvious implications for potential remobilization of frozen soil carbon pools under warmer temperatures. Additionally, warmer and drier conditions may increase fire activity and severity, which may exacerbate rates of permafrost thaw and carbon remobilization relative to climate alone. The mapping of permafrost distribution across Alaska is important for land-use planning, environmental assessments, and a wide-array of geophysical studies.

  8. Maxent modelling for predicting the potential distribution of Thai Palms

    DEFF Research Database (Denmark)

    Tovaranonte, Jantrararuk; Barfod, Anders S.; Overgaard, Anne Blach

    2011-01-01

    Increasingly species distribution models are being used to address questions related to ecology, biogeography and species conservation on global and regional scales. We used the maximum entropy approach implemented in the MAXENT programme to build a habitat suitability model for Thai palms based...... overprediction of species distribution ranges. The models with the best predictive power were found by calculating the area under the curve (AUC) of receiver-operating characteristic (ROC). Here, we provide examples of contrasting predicted species distribution ranges as well as a map of modeled palm diversity...

  9. Investigation of the surface potential of TiO2 (110) by frequency-modulation Kelvin probe force microscopy.

    Science.gov (United States)

    Kou, Lili; Li, Yan Jun; Kamijyo, Takeshi; Naitoh, Yoshitaka; Sugawara, Yasuhiro

    2016-12-16

    We investigate the surface potential distribution on a TiO 2 (110)-1 × 1 surface by Kelvin probe force microscopy (KPFM) and atom-dependent bias-distance spectroscopic mapping. The experimental results demonstrate that the local contact potential difference increases on twofold-coordinated oxygen sites, and decreases on OH defects and fivefold-coordinated Ti sites. We propose a qualitative model to explain the origin of the surface potential of TiO 2 (110). We qualitatively calculate the surface potential induced by chemical potential and permanent surface dipole. The calculated results agree with our experimental ones. Therefore, we suggest that the surface potential of TiO 2 (110) is dominated not only by the permanent surface dipole between the tip apex atom and surface, but also by the dipoles induced by the chemical interaction between the tip and sample. The KPFM technique demonstrate the possibility of investigation of the charge transfer phenomenon on TiO 2 surface under gas conditions. It is useful for the elucidation of the mechanism of the catalytic reactions.

  10. X-ray evaluation of residual stress distributions within surface machined layer generated by surface machining and sequential welding

    International Nuclear Information System (INIS)

    Taniguchi, Yuu; Okano, Shigetaka; Mochizuki, Masahito

    2017-01-01

    The excessive tensile residual stress generated by welding after surface machining may be an important factor to cause stress corrosion cracking (SCC) in nuclear power plants. Therefore we need to understand and control the residual stress distribution appropriately. In this study, residual stress distributions within surface machined layer generated by surface machining and sequential welding were evaluated by X-ray diffraction method. Depth directional distributions were also investigated by electrolytic polishing. In addition, to consider the effect of work hardened layer on the residual stress distributions, we also measured full width at half maximum (FWHM) obtained from X-ray diffraction. Testing material was a low-carbon austenitic stainless steel type SUS316L. Test specimens were prepared by surface machining with different cutting conditions. Then, bead-on-plate welding under the same welding condition was carried out on the test specimens with different surface machined layer. As a result, the tensile residual stress generated by surface machining increased with increasing cutting speed and showed nearly uniform distributions on the surface. Furthermore, the tensile residual stress drastically decreased with increasing measurement depth within surface machined layer. Then, the residual stress approached 0 MPa after the compressive value showed. FWHM also decreased drastically with increasing measurement depth and almost constant value from a certain depth, which was almost equal regardless of the machining condition, within surface machined layer in all specimens. After welding, the transverse distribution of the longitudinal residual stress varied in the area apart from the weld center according to machining conditions and had a maximum value in heat affected zone. The magnitude of the maximum residual stress was almost equal regardless of the machining condition and decreased with increasing measurement depth within surface machined layer. Finally, the

  11. Off to new shores: Modeling the potential distribution and future range expansion of larger foraminifera

    Science.gov (United States)

    Weinmann, A. E.; Rödder, D.; Lötters, S.; Langer, M. R.

    2012-04-01

    The distribution of larger foraminifera is strongly controlled by environmental variables, especially temperature. Most of today's taxa of larger foraminifera are restricted to tropical and subtropical regions (between 30° N and 30° S) and their minimum temperature limits are governed by the 14 to 20° C isotherms. However, during times of extensive global warming (e.g. the Eocene and Miocene), larger foraminifera have been found as far North as 50° N (North America and Central Europe) as well as towards 40° S in New Zealand. It has been stated that larger foraminifera are more tolerant of rising sea surface temperatures than reef-building corals. As such they may play a more prominent role as future reef framework and carbonate producers in a steadily warming ocean. During the last century, sea surface temperatures have been rising significantly due to higher CO2 concentrations in the atmosphere. This trend is expected to continue and climate change scenarios for 2100 suggest a further increase by 1 to 6° C (IPCC Synthesis Report, 2007). We applied Species Distribution Models (SDMs) on several taxa of larger foraminifera in order to evaluate their potential distribution under current climate conditions and to predict range expansions within the next 40 years. The studied taxa include Archaias angulatus, which is regionally distributed within the Caribbean region, Calcarina spp., which occurs in the Indo-Pacific area and the true circumglobal taxon Amphistegina spp. Under present climate, Amphistegina spp. shows the widest distribution range due to its greater temperature tolerance. Both Archaias angulatus and Calcarina spp. display potential distributions that cover currently uninhabitet regions, suggesting that weak dispersal abilities are major reasons for their limited distributions. Under future climate, Archaias angulatus and Calcarina spp. show an increase in habitat suitability within their native occurrence ranges, suggesting that their tolerance for

  12. Global potential energy surface of ground state singlet spin O4

    Science.gov (United States)

    Mankodi, Tapan K.; Bhandarkar, Upendra V.; Puranik, Bhalchandra P.

    2018-02-01

    A new global potential energy for the singlet spin state O4 system is reported using CASPT2/aug-cc-pVTZ ab initio calculations. The geometries for the six-dimensional surface are constructed using a novel point generation scheme that employs randomly generated configurations based on the beta distribution. The advantage of this scheme is apparent in the reduction of the number of required geometries for a reasonably accurate potential energy surface (PES) and the consequent decrease in the overall computational effort. The reported surface matches well with the recently published singlet surface by Paukku et al. [J. Chem. Phys. 147, 034301 (2017)]. In addition to the O4 PES, the ground state N4 PES is also constructed using the point generation scheme and compared with the existing PES [Y. Paukku et al., J. Chem. Phys. 139, 044309 (2013)]. The singlet surface is constructed with the aim of studying high energy O2-O2 collisions and predicting collision induced dissociation cross section to be used in simulating non-equilibrium aerothermodynamic flows.

  13. Modeling and experiments of the adhesion force distribution between particles and a surface.

    Science.gov (United States)

    You, Siming; Wan, Man Pun

    2014-06-17

    Due to the existence of surface roughness in real surfaces, the adhesion force between particles and the surface where the particles are deposited exhibits certain statistical distributions. Despite the importance of adhesion force distribution in a variety of applications, the current understanding of modeling adhesion force distribution is still limited. In this work, an adhesion force distribution model based on integrating the root-mean-square (RMS) roughness distribution (i.e., the variation of RMS roughness on the surface in terms of location) into recently proposed mean adhesion force models was proposed. The integration was accomplished by statistical analysis and Monte Carlo simulation. A series of centrifuge experiments were conducted to measure the adhesion force distributions between polystyrene particles (146.1 ± 1.99 μm) and various substrates (stainless steel, aluminum and plastic, respectively). The proposed model was validated against the measured adhesion force distributions from this work and another previous study. Based on the proposed model, the effect of RMS roughness distribution on the adhesion force distribution of particles on a rough surface was explored, showing that both the median and standard deviation of adhesion force distribution could be affected by the RMS roughness distribution. The proposed model could predict both van der Waals force and capillary force distributions and consider the multiscale roughness feature, greatly extending the current capability of adhesion force distribution prediction.

  14. Critical insight into the influence of the potential energy surface on fission dynamics

    International Nuclear Information System (INIS)

    Mazurek, K.; Schmitt, C.; Wieleczko, J. P.; Ademard, G.; Nadtochy, P. N.

    2011-01-01

    The present work is dedicated to a careful investigation of the influence of the potential energy surface on the fission process. The time evolution of nuclei at high excitation energy and angular momentum is studied by means of three-dimensional Langevin calculations performed for two different parametrizations of the macroscopic potential: the Finite Range Liquid Drop Model (FRLDM) and the Lublin-Strasbourg Drop (LSD) prescription. Depending on the mass of the system, the topology of the potential throughout the deformation space of interest in fission is observed to noticeably differ within these two approaches, due to the treatment of curvature effects. When utilized in the dynamical calculation as the driving potential, the FRLDM and LSD models yield similar results in the heavy-mass region, whereas the predictions can be strongly dependent on the Potential Energy Surface (PES) for medium-mass nuclei. In particular, the mass, charge, and total kinetic energy distributions of the fission fragments are found to be narrower with the LSD prescription. The influence of critical model parameters on our findings is carefully investigated. The present study sheds light on the experimental conditions and signatures well suited for constraining the parametrization of the macroscopic potential. Its implication regarding the interpretation of available experimental data is briefly discussed.

  15. The diversity and distribution of fungi on residential surfaces.

    Directory of Open Access Journals (Sweden)

    Rachel I Adams

    Full Text Available The predominant hypothesis regarding the composition of microbial assemblages in indoor environments is that fungal assemblages are structured by outdoor air with a moderate contribution by surface growth, whereas indoor bacterial assemblages represent a mixture of bacteria entered from outdoor air, shed by building inhabitants, and grown on surfaces. To test the fungal aspect of this hypothesis, we sampled fungi from three surface types likely to support growth and therefore possible contributors of fungi to indoor air: drains in kitchens and bathrooms, sills beneath condensation-prone windows, and skin of human inhabitants. Sampling was done in replicated units of a university-housing complex without reported mold problems, and sequences were analyzed using both QIIME and the new UPARSE approach to OTU-binning, to the same result. Surfaces demonstrated a mycological profile similar to that of outdoor air from the same locality, and assemblages clustered by surface type. "Weedy" genera typical of indoor air, such as Cladosporium and Cryptococcus, were abundant on sills, as were a diverse set of fungi of likely outdoor origin. Drains supported more depauperate assemblages than the other surfaces and contained thermotolerant genera such as Exophiala, Candida, and Fusarium. Most surprising was the composition detected on residents' foreheads. In addition to harboring Malassezia, a known human commensal, skin also possessed a surprising richness of non-resident fungi, including plant pathogens such as ergot (Claviceps purperea. Overall, fungal richness across indoor surfaces was high, but based on known autecologies, most of these fungi were unlikely to be growing on surfaces. We conclude that while some endogenous fungal growth on typical household surfaces does occur, particularly on drains and skin, all residential surfaces appear - to varying degrees - to be passive collectors of airborne fungi of putative outdoor origin, a view of the origins

  16. Global distribution of Earth's surface shortwave radiation budget

    Directory of Open Access Journals (Sweden)

    N. Hatzianastassiou

    2005-01-01

    Full Text Available The monthly mean shortwave (SW radiation budget at the Earth's surface (SRB was computed on 2.5-degree longitude-latitude resolution for the 17-year period from 1984 to 2000, using a radiative transfer model accounting for the key physical parameters that determine the surface SRB, and long-term climatological data from the International Satellite Cloud Climatology Project (ISCCP-D2. The model input data were supplemented by data from the National Centers for Environmental Prediction - National Center for Atmospheric Research (NCEP-NCAR and European Center for Medium Range Weather Forecasts (ECMWF Global Reanalysis projects, and other global data bases such as TIROS Operational Vertical Sounder (TOVS and Global Aerosol Data Set (GADS. The model surface radiative fluxes were validated against surface measurements from 22 stations of the Baseline Surface Radiation Network (BSRN covering the years 1992-2000, and from 700 stations of the Global Energy Balance Archive (GEBA, covering the period 1984-2000. The model is in good agreement with BSRN and GEBA, with a negative bias of 14 and 6.5 Wm-2, respectively. The model is able to reproduce interesting features of the seasonal and geographical variation of the surface SW fluxes at global scale. Based on the 17-year average model results, the global mean SW downward surface radiation (DSR is equal to 171.6 Wm-2, whereas the net downward (or absorbed surface SW radiation is equal to 149.4 Wm-2, values that correspond to 50.2 and 43.7% of the incoming SW radiation at the top of the Earth's atmosphere. These values involve a long-term surface albedo equal to 12.9%. Significant increasing trends in DSR and net DSR fluxes were found, equal to 4.1 and 3.7 Wm-2, respectively, over the 1984-2000 period (equivalent to 2.4 and 2.2 Wm-2 per decade, indicating an increasing surface solar radiative heating. This surface SW radiative heating is primarily attributed to clouds, especially low-level, and secondarily to

  17. Distribution and Potential Impact of Feral Cotton on the ...

    African Journals Online (AJOL)

    Transgenic Bt cotton with insecticidal properties presents a potential solution to the bollworm infestation in Tanzania. However, concerns associated with transgenic crops viz.; transgene flow to wild and feral relatives, increased potential for resistance evolution, need to be addressed prior to adoption of any transgenic crop.

  18. Distribution of genes associated with yield potential and water ...

    Indian Academy of Sciences (India)

    [Gao Z., Shi Z., Zhang A. and Guo J. 2015 Distribution of genes associated with yield potenial and water-saving in Chinese Zone II wheat detected by developed functional markers. J. Genet. 94, 35–42]. Introduction. The Yellow and Huai wheat production region (Zone II), where Shijiazhuang irrigation district (SID) is located, ...

  19. Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads

    2008-01-01

    is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-photoemission spectroscopy measurements. This comparison shows that the modified Delta SCF method gives results in close agreement with experiment, significantly closer than the comparable methods. For N2 adsorbed on ruthenium (0001) we map out a two-dimensional part of the potential energy surfaces in the ground state...

  20. Homogenization mechanism of the residual surface potential of insulating specimens under electron beam irradiation

    International Nuclear Information System (INIS)

    Li Jingjing; Zhang Haibo; Feng Renjian

    2007-01-01

    A homogenized surface potential is desirable for the observation of a pre-irradiated insulating specimen using a scanning electron microscope because the residual surface potential may affect the imaging properties of the specimen. To homogenize the residual surface potential, the specimen should be subjected to the irradiation of an electron beam with the total electron yield greater than one. The expression of the equilibrium potential is derived based on the charge balance condition in the equilibrium state and the potential value is found to increase mainly with the secondary electron (SE) yield and the most probable emission energy of SEs. Further numerical calculations of SE trajectories show that affected by different surface potentials, SEs leave or return to the specimen surface to change the net charge flux into the specimen. This thereby increases the surface potential below the equilibrium potential and decreases that above the equilibrium potential, homogenizing the surface potential

  1. An Accurate Potential Energy Surface for H2O

    Science.gov (United States)

    Schwenke, David W.; Partridge, Harry; Langhoff, Stephen R. (Technical Monitor)

    1997-01-01

    We have carried out extensive high quality ab initio electronic structure calculations of the ground state potential energy surface (PES) and dipole moment function (DMF) for H2O. A small adjustment is made to the PES to improve the agreement of line positions from theory and experiment. The theoretical line positions are obtained from variational ro-vibrational calculations using the exact kinetic energy operator. For the lines being fitted, the root-mean-square error was reduced from 6.9 to 0.08 /cm. We were then able to match 30,092 of the 30,117 lines from the HITRAN 96 data base to theoretical lines, and 80% of the line positions differed less than 0.1 /cm. About 3% of the line positions in the experimental data base appear to be incorrect. Theory predicts the existence of many additional weak lines with intensities above the cutoff used in the data base. To obtain results of similar accuracy for HDO, a mass dependent correction to the PH is introduced and is parameterized by simultaneously fitting line positions for HDO and D2O. The mass dependent PH has good predictive value for T2O and HTO. Nonadiabatic effects are not explicitly included. Line strengths for vibrational bands summed over rotational levels usually agree well between theory and experiment, but individual line strengths can differ greatly. A high temperature line list containing about 380 million lines has been generated using the present PES and DMF

  2. Numerical Predictions of Air Distribution in Rooms - Status and Potentials

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    The purpose of an air distribution system in a ventilated room is to supply fresh air, remove heat load or supply heating, and create a pleasant and uniform climate in the occupied zone. A pleasant climate is in this context defined as a fairly low air velocity, small velocity and temperature gra...... gradients through the room and a low concentration of polluting substances, if any....

  3. Cloud Masking and Surface Temperature Distribution in the Polar Regions Using AVHRR and other Satellite Data

    Science.gov (United States)

    Comiso, Joey C.

    1995-01-01

    Surface temperature is one of the key variables associated with weather and climate. Accurate measurements of surface air temperatures are routinely made in meteorological stations around the world. Also, satellite data have been used to produce synoptic global temperature distributions. However, not much attention has been paid on temperature distributions in the polar regions. In the polar regions, the number of stations is very sparse. Because of adverse weather conditions and general inaccessibility, surface field measurements are also limited. Furthermore, accurate retrievals from satellite data in the region have been difficult to make because of persistent cloudiness and ambiguities in the discrimination of clouds from snow or ice. Surface temperature observations are required in the polar regions for air-sea-ice interaction studies, especially in the calculation of heat, salinity, and humidity fluxes. They are also useful in identifying areas of melt or meltponding within the sea ice pack and the ice sheets and in the calculation of emissivities of these surfaces. Moreover, the polar regions are unique in that they are the sites of temperature extremes, the location of which is difficult to identify without a global monitoring system. Furthermore, the regions may provide an early signal to a potential climate change because such signal is expected to be amplified in the region due to feedback effects. In cloud free areas, the thermal channels from infrared systems provide surface temperatures at relatively good accuracies. Previous capabilities include the use of the Temperature Humidity Infrared Radiometer (THIR) onboard the Nimbus-7 satellite which was launched in 1978. Current capabilities include the use of the Advance Very High Resolution Radiometer (AVHRR) aboard NOAA satellites. Together, these two systems cover a span of 16 years of thermal infrared data. Techniques for retrieving surface temperatures with these sensors in the polar regions have

  4. Pore Scale Heterogeneity in the Mineral Distribution, Surface Area and Adsorption in Porous Rocks

    Science.gov (United States)

    Lai, P. E. P.; Krevor, S. C.

    2014-12-01

    The impact of heterogeneity in chemical transport and reaction is not understood in continuum (Darcy/Fickian) models of reactive transport. This is manifested in well-known problems such as scale dependent dispersion and discrepancies in reaction rate observations made at laboratory and field scales [1]. Additionally, this is a source of uncertainty for carbon dioxide injection, which produces a reactive fluid-rock system particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2, 3]. We use x-ray micro tomography to describe the non-normal 3-dimensional distribution of reactive surface area within a porous medium according to distinct mineral groups. Using in-house image processing techniques, thin sections, nitrogen BET surface area, backscattered electron imaging and energy dispersive spectroscopy, we compare the surface area of each mineral phase to those obtained from x-ray CT imagery. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be characterized at multiple length scales for an accurate description of reactive transport. We combine the mineral specific surface area characterisation to dynamic tomography, imaging the flow of water and solutes, to observe flow dependent and mineral specific adsorption. The observations may contribute to the incorporation of experimentally based statistical descriptions of pore scale heterogeneity in reactive transport into upscaled models, moving it closer to predictive capabilities for field scale

  5. Humidity distribution affected by freely exposed water surfaces

    DEFF Research Database (Denmark)

    Hygum, Morten Arnfeldt; Popok, Vladimir

    2014-01-01

    Accurate models for the water vapor flux at a water-air interface are required in various scientific, reliability and civil engineering aspects. Here, a study of humidity distribution in a container with air and freely exposed water is presented. A model predicting a spatial distribution and time...... evolution of relative humidity based on statistical rate theory and computational fluid dynamics is developed. In our approach we use short-term steady-state steps to simulate the slowly evolving evaporation in the system. Experiments demonstrate considerably good agreement with the computer modeling...

  6. Potential Energy Surface of NO on Pt(997: Adsorbed States and Surface Diffusion

    Directory of Open Access Journals (Sweden)

    N. Tsukahara

    2012-01-01

    Full Text Available The potential energy surface (PES of NO on Pt(997 has been elucidated: the adsorption states and diffusion processes of NO on Pt(997 at low coverage were investigated by using infrared reflection absorption spectroscopy (IRAS and scanning tunneling microscopy (STM. When NO molecules adsorb on a surface at a low temperature (11 K, each molecule transiently migrates on the surface from the first impact point to a possible adsorption site. We found that there are four stable adsorption sites for NO on Pt(997: a bridge site of the upper step, an fcc- (or hcp- hollow site of the terrace, an on-top site of the terrace, and an fcc-hollow site of the lower step. At higher temperatures above 45 K, NO molecules start to migrate thermally to more stable adsorption sites on a terrace, and they are finally trapped at the bridge sites of the step, which are the most stable among the four sites.

  7. The measurement of potential distribution of plasma in MM-4 fusion device

    International Nuclear Information System (INIS)

    Tian Zhongyu; Ming Linzhou; Feng Xiaozhen; Feng Chuntang; Yi Youjun; Wang Jihai; Liu Yihua

    1988-11-01

    Some experimental results of the potential distribution in MM-4 fusion device are presented by measuring the floating potential of probe. The results showed that the distribution of axial potential is asymmetrical, but the radial potential is symmetrical. There are double ion potential wells in the plasma. The depth of the deepest potential well become deeper is the strength of the magnetic field and injection current are increasing. The location of the deepest well is moved towards the device center along with the increasing of injection energy. This is different from others results. The mechanism of causing this distribution in also discussed

  8. Prediction of residual stress distributions due to surface machining and welding and crack growth simulation under residual stress distribution

    International Nuclear Information System (INIS)

    Ihara, Ryohei; Katsuyama, JInya; Onizawa, Kunio; Hashimoto, Tadafumi; Mikami, Yoshiki; Mochizuki, Masahito

    2011-01-01

    Research highlights: → Residual stress distributions due to welding and machining are evaluated by XRD and FEM. → Residual stress due to machining shows higher tensile stress than welding near the surface. → Crack growth analysis is performed using calculated residual stress. → Crack growth result is affected machining rather than welding. → Machining is an important factor for crack growth. - Abstract: In nuclear power plants, stress corrosion cracking (SCC) has been observed near the weld zone of the core shroud and primary loop recirculation (PLR) pipes made of low-carbon austenitic stainless steel Type 316L. The joining process of pipes usually includes surface machining and welding. Both processes induce residual stresses, and residual stresses are thus important factors in the occurrence and propagation of SCC. In this study, the finite element method (FEM) was used to estimate residual stress distributions generated by butt welding and surface machining. The thermoelastic-plastic analysis was performed for the welding simulation, and the thermo-mechanical coupled analysis based on the Johnson-Cook material model was performed for the surface machining simulation. In addition, a crack growth analysis based on the stress intensity factor (SIF) calculation was performed using the calculated residual stress distributions that are generated by welding and surface machining. The surface machining analysis showed that tensile residual stress due to surface machining only exists approximately 0.2 mm from the machined surface, and the surface residual stress increases with cutting speed. The crack growth analysis showed that the crack depth is affected by both surface machining and welding, and the crack length is more affected by surface machining than by welding.

  9. Assessment of the Economic Potential of Distributed Wind in Colorado, Minnesota, and New York

    Energy Technology Data Exchange (ETDEWEB)

    McCabe, Kevin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sigrin, Benjamin O. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lantz, Eric J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mooney, Meghan E. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-01-03

    This work seeks to identify current and future spatial distributions of economic potential for behind-the-meter distributed wind, serving primarily rural or suburban homes, farms, and manufacturing facilities in Colorado, Minnesota, and New York. These states were identified by technical experts based on their current favorability for distributed wind deployment. We use NREL's Distributed Wind Market Demand Model (dWind) (Lantz et al. 2017; Sigrin et al. 2016) to identify and rank counties in each of the states by their overall and per capita potential. From this baseline assessment, we also explore how and where improvements in cost, performance, and other market sensitivities affect distributed wind potential.

  10. Pesticides in surface waters: distribution, trends, and governing factors

    Science.gov (United States)

    Larson, Steven J.; Capel, Paul D.; Majewski, Michael

    1997-01-01

    Pesticde use in agriculture and non-agriculture settings has increased dramatically over the last several decades. Concern about adverse effects on the environment and human health has spurred an enormous amount of research into their environmental behavior and fate. Pesticides in Surface Waters presents a comprehensive summary of this research. This book evaluates published studies that focus on measuring pesticide concentration. The studies chosen include peer reviewed scientific literature, government reports, laboratory studies, and those using microcosms and artificial streams and ponds. The authors used this information to develop their overview of pesticide contamination of surface waters. The exhaustive compilation of data along with the fundamental science make this book essential for those involved in pesticide use, environmental protection, water quality, and human or ecological risk assessment. Pesticides in Surface Waters covers the results of actual studies, sources of pesticides to surface water, fate and transport, and environmental significance. Hundreds of data-packed tables, maps, charts, and drawings illustrate the key points, making research and application easy and cost effective.

  11. The effect of surface albedo and grain size distribution on ...

    African Journals Online (AJOL)

    Sand dams are very useful in arid and semi arid lands (ASALs) as facilities for water storage and conservation. Soils in ASALs are mainly sandy and major water loss is by evaporation and infiltration. This study investigated the effect of sand media characteristics, specifically surface albedo, grain size and stratification on ...

  12. CONSTRAINING THE NFW POTENTIAL WITH OBSERVATIONS AND MODELING OF LOW SURFACE BRIGHTNESS GALAXY VELOCITY FIELDS

    International Nuclear Information System (INIS)

    Kuzio de Naray, Rachel; McGaugh, Stacy S.; Mihos, J. Christopher

    2009-01-01

    We model the Navarro-Frenk-White (NFW) potential to determine if, and under what conditions, the NFW halo appears consistent with the observed velocity fields of low surface brightness (LSB) galaxies. We present mock DensePak Integral Field Unit (IFU) velocity fields and rotation curves of axisymmetric and nonaxisymmetric potentials that are well matched to the spatial resolution and velocity range of our sample galaxies. We find that the DensePak IFU can accurately reconstruct the velocity field produced by an axisymmetric NFW potential and that a tilted-ring fitting program can successfully recover the corresponding NFW rotation curve. We also find that nonaxisymmetric potentials with fixed axis ratios change only the normalization of the mock velocity fields and rotation curves and not their shape. The shape of the modeled NFW rotation curves does not reproduce the data: these potentials are unable to simultaneously bring the mock data at both small and large radii into agreement with observations. Indeed, to match the slow rise of LSB galaxy rotation curves, a specific viewing angle of the nonaxisymmetric potential is required. For each of the simulated LSB galaxies, the observer's line of sight must be along the minor axis of the potential, an arrangement that is inconsistent with a random distribution of halo orientations on the sky.

  13. Distribution, Community Composition, and Potential Metabolic Activity of Bacterioplankton in an Urbanized Mediterranean Sea Coastal Zone.

    Science.gov (United States)

    Richa, Kumari; Balestra, Cecilia; Piredda, Roberta; Benes, Vladimir; Borra, Marco; Passarelli, Augusto; Margiotta, Francesca; Saggiomo, Maria; Biffali, Elio; Sanges, Remo; Scanlan, David J; Casotti, Raffaella

    2017-09-01

    Bacterioplankton are fundamental components of marine ecosystems and influence the entire biosphere by contributing to the global biogeochemical cycles of key elements. Yet, there is a significant gap in knowledge about their diversity and specific activities, as well as environmental factors that shape their community composition and function. Here, the distribution and diversity of surface bacterioplankton along the coastline of the Gulf of Naples (GON; Italy) were investigated using flow cytometry coupled with high-throughput sequencing of the 16S rRNA gene. Heterotrophic bacteria numerically dominated the bacterioplankton and comprised mainly Alphaproteobacteria , Gammaproteobacteria , and Bacteroidetes Distinct communities occupied river-influenced, coastal, and offshore sites, as indicated by Bray-Curtis dissimilarity, distance metric (UniFrac), linear discriminant analysis effect size (LEfSe), and multivariate analyses. The heterogeneity in diversity and community composition was mainly due to salinity and changes in environmental conditions across sites, as defined by nutrient and chlorophyll a concentrations. Bacterioplankton communities were composed of a few dominant taxa and a large proportion (92%) of rare taxa (here defined as operational taxonomic units [OTUs] accounting for bacterioplankton in coastal zones is of critical importance, considering that these areas are highly productive and anthropogenically impacted. Their richness and evenness, as well as their potential activity, are very important to assess ecosystem health and functioning. Here, we investigated bacterial distribution, community composition, and potential metabolic activity in the GON, which is an ideal test site due to its heterogeneous environment characterized by a complex hydrodynamics and terrestrial inputs of varied quantities and quality. Our study demonstrates that bacterioplankton communities in this region are highly diverse and strongly regulated by a combination of

  14. Evaluation of the immunodiagnostic potential of a recombinant surface protein domain from Acanthamoeba castellanii.

    Science.gov (United States)

    Sánchez, Alemao G Carpinteyro; Virginio, Veridiana Gomes; Maschio, Vinicius José; Ferreira, Henrique Bunselmeyer; Rott, Marilise Brittes

    2016-10-01

    Acanthamoeba spp. are free-living protists widely distributed in environment, able to cause keratitis, encephalitis and skin lesions in humans and animals. Acanthamoeba spp. exist in two forms: an infective trophozoite and a dormant cyst. Several factors contribute to the pathogenesis of Acanthamoeba spp. The parasite adhesion to the host cell is the primary step for infection and is mediated by a mannose binding-protein, expressed in the surface and considered the main pathogenicity factor in Acanthamoeba spp. So far, there was no evidence of another surface protein of Acanthamoeba spp. relevant for host invasion or infection by these organisms. The aims of this study were to identify and characterize an Acanthamoeba castellanii surface protein and to evaluate its diagnostic potential. In silico predictions of surface proteins allowed to identify the A. castellanii calreticulin as a possible surface antigen. The coding sequence of a predicted extracellular domain of A. castellanii calreticulin was cloned by in vivo homologous recombination and the recombinant polypeptide (AcCRT29-130) was produced. Its immunodiagnostic potential was assessed in a recombinant antigen-based ELISA with sera from experimentally infected rats that developed keratitis and encephalitis, and sera from patients with encephalitis. The AcCRT29-130 was significantly more recognized by sera from encephalitis infected rats in comparison with the non-infected controls. Human sera from encephalitis patients, however presented no significant response. These results showed the AcCRT29-130 potential for A. castellanii infection immunodiagnosis in animals, with further studies being required for assessment of its use for human infections.

  15. Predicting the potential distribution of invasive silver carp ...

    African Journals Online (AJOL)

    The potential range of silver carp in South Africa was identified based on ecological niche modelling (ENM) using the maximum entropy method. Models were constructed using occurrence records and a defined background, and calibrated using a k-fold method. The area under the receiver operating characteristics curve ...

  16. Vertical distribution of dehalogenating bacteria in mangrove sediment and their potential to remove polybrominated diphenyl ether contamination.

    Science.gov (United States)

    Pan, Ying; Chen, Juan; Zhou, Haichao; Farzana, Shazia; Tam, Nora F Y

    2017-11-30

    The removal and degradation of polybrominated diphenyl ethers (PBDEs) in sediments are not clear. The vertical distribution of total and dehalogenating bacteria in sediment cores collected from a typical mangrove swamp in South China and their intrinsic degradation potential were investigated. These bacterial groups had the highest abundances in surface sediments (0-5cm). A 5-months microcosm experiment also showed that surface sediments had the highest rate to remove BDE-47 than deeper sediments (5-30cm) under anaerobic condition. The deeper sediments, being more anaerobic, had lower population of dehalogenating bacteria leading to a weaker BDE-47 removal potential than surface sediments. Stepwise multiple regression analysis indicated that Dehalococcoides spp. were the most important dehalogenating bacteria affecting the anaerobic removal of BDE-47 in mangrove sediments. This is the first study reporting that mangrove sediments harbored diverse groups of dehalogenating bacteria and had intrinsic potential to remove PBDE contamination. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Distribution and variation of water potential for unsaturated water vadose through two-layer porous media

    International Nuclear Information System (INIS)

    Wang Zhiming; Yao Laigen; Jiang Hong

    2004-01-01

    Water potential reflects energy level of soil water and the gradient of water potential is an impotent factor describing direction and velocity of water flow. The main experimental methods and results of determining water potential distribution and variation for unsaturated water vadose passing through two-layer porous media made of loess (fine particle) and quartz sand (coarse particle) are introduced in this paper in order to analyze and explain further detouring flow phenomenon observed in former work. It can be seen from the results that: water potential in quartz sand layer decreases with increasing thickness of the quartz sand layer under fixed sprinkling rate and increases with increasing sprinkling rate under fixed thickness of quartz sand layer; some of water above quartz sand layer flows down through the quartz sand layer and some flows down along edges of the quartz sand layer; some of water detoured the quartz sand layer flows into the region below the quartz sand layer closely along lower surface of the quartz sand layer. These are some phenomena to be worthing further study. (authors)

  18. Distribution of small channels on the Martian surface

    Science.gov (United States)

    Pieri, D.

    1976-01-01

    The distribution of small channels on Mars has been mapped from Mariner 9 images at the 1:5,000,000 scale. The small channels referred to here are small valleys ranging in width from the resolution limit of the Mariner 9 wide-angle images (about 1 km) to about 10 km. The greatest density of small channels occurs in dark cratered terrain. This dark zone forms a broad subequatorial band around the planet. The observed distribution may be the result of decreased small-channel visibility in bright areas due to obscuration by a high albedo dust or sediment mantle. Crater densities within two small-channel segments show crater size-frequency distributions consistent with those of the oldest of the heavily cratered plains units. Such crater densities coupled with the almost exclusive occurrence of small channels in old cratered terrain and the generally degraded appearance of small channels in the high-resolution images (about 100 m) imply a major episode of small-channel formation early in Martian geologic history.

  19. PHYTOPLANKTON AND BIOMASS DISTRIBUTION AT POTENTIAL OTEC SITES

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, P.W.; Horne, A.J.

    1979-06-01

    Net or large phytoplankton species composition and most phytoplankton abundance was measured at three OTEC sites. In the Gulf of Mexico and Hawaii, diatoms dominated while the blue-green algae Trichodesmium was most common at Puerto Rico. The species ratio of diatoms to dinoflagellates was approximately 1:1. The species diversity varied from site to site, Hawaii > Puerto Rico > Gulf of Mexico. Chlorophyll a, which is a measure of the pigment of all algae size ranges, showed a subsurface peak of 0.14-0.4 g per liter at 75 to 125 m. Occasional surface peaks up to 0.4 pg per liter occurred. Further refinement of collection techniques is needed to delineate the subtle environmental effects expected by OTEC plant discharges.

  20. Phytoplankton and biomass distribution at potential OTEC sites

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, P.W.; Horne, A.J.

    1979-06-01

    Net or large phytoplankton species composition and most phytoplankton abundance was measured at three OTEC sites. In the Gulf of Mexico and'Hawaii, diatoms dominated while the blue-green algae Trichodesmium was most common at Puerto Rico. The species ratio of diatoms to dinoflagellates was approximately 1:1. The species diversity varied from site to site, Hawaii > Puerto Rico > Gulf of Mexico. Chlorophyll a, which is a measure of the pigment of all algae size ranges, showed a subsurface peak of 0.14 to 0.4 g per liter at 75 to 125 m. Occasional surface peaks upto 0.4 ..mu..g per liter occurred. Further refinement of collection techniques is needed to delineate the subtle environmental effects expected by OTEC plant discharges.

  1. Surface-water radon-222 distribution along the west-central Florida shelf

    Science.gov (United States)

    Smith, C.G.; Robbins, L.L.

    2012-01-01

    In February 2009 and August 2009, the spatial distribution of radon-222 in surface water was mapped along the west-central Florida shelf as collaboration between the Response of Florida Shelf Ecosystems to Climate Change project and a U.S. Geological Survey Mendenhall Research Fellowship project. This report summarizes the surface distribution of radon-222 from two cruises and evaluates potential physical controls on radon-222 fluxes. Radon-222 is an inert gas produced overwhelmingly in sediment and has a short half-life of 3.8 days; activities in surface water ranged between 30 and 170 becquerels per cubic meter. Overall, radon-222 activities were enriched in nearshore surface waters relative to offshore waters. Dilution in offshore waters is expected to be the cause of the low offshore activities. While thermal stratification of the water column during the August survey may explain higher radon-222 activities relative to the February survey, radon-222 activity and integrated surface-water inventories decreased exponentially from the shoreline during both cruises. By estimating radon-222 evasion by wind from nearby buoy data and accounting for internal production from dissolved radium-226, its radiogenic long-lived parent, a simple one-dimensional model was implemented to determine the role that offshore mixing, benthic influx, and decay have on the distribution of excess radon-222 inventories along the west Florida shelf. For multiple statistically based boundary condition scenarios (first quartile, median, third quartile, and maximum radon-222 inshore of 5 kilometers), the cross-shelf mixing rates and average nearshore submarine groundwater discharge (SGD) rates varied from 100.38 to 10-3.4 square kilometers per day and 0.00 to 1.70 centimeters per day, respectively. This dataset and modeling provide the first attempt to assess cross-shelf mixing and SGD on such a large spatial scale. Such estimates help scale up SGD rates that are often made at 1- to 10-meter

  2. Surface grafted polymer brushes: potential applications in dengue biosensors

    International Nuclear Information System (INIS)

    Baratela, Fernando Jose Costa; Higa, Olga Zazuco; Faria, Henrique Antonio Mendonca de; Queiroz, Alvaro Antonio Alencar de

    2013-01-01

    A polymer brush membrane-based ultrasensitive biosensor for dengue diagnosis was constructed using poly(hydroxyethyl methacrylate) (PHEMA) brushes immobilized onto low density polyethylene (LDPE) films. LDPE surface films were initially modified by Ar + ion irradiation to activate the polymer surface. Subsequently, graft polymerization of 2-hydroxyethyl methacrylate onto the activated LDPE surface was carried out under aqueous conditions to create patterned polymer brushes of PHEMA. The grafted PHEMA brushes were characterized by Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis. The SEM observations showed that selective surface activation with Ar+ implantation and graft polymerization on the selectively activated surface had occurred. The PHEMA brushes were electrically characterized in the presence of concentrations of human immunoglobulin (IgG). The proposed amperometric biosensor was successfully used for determination of IgG in physiologic samples with excellent responses. (author)

  3. Surface grafted polymer brushes: potential applications in dengue biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Baratela, Fernando Jose Costa; Higa, Olga Zazuco, E-mail: ozahiga@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Faria, Henrique Antonio Mendonca de; Queiroz, Alvaro Antonio Alencar de, E-mail: alencar@unifei.edu.br [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Instituto de Fisica e Quimica

    2013-07-01

    A polymer brush membrane-based ultrasensitive biosensor for dengue diagnosis was constructed using poly(hydroxyethyl methacrylate) (PHEMA) brushes immobilized onto low density polyethylene (LDPE) films. LDPE surface films were initially modified by Ar{sup +} ion irradiation to activate the polymer surface. Subsequently, graft polymerization of 2-hydroxyethyl methacrylate onto the activated LDPE surface was carried out under aqueous conditions to create patterned polymer brushes of PHEMA. The grafted PHEMA brushes were characterized by Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis. The SEM observations showed that selective surface activation with Ar+ implantation and graft polymerization on the selectively activated surface had occurred. The PHEMA brushes were electrically characterized in the presence of concentrations of human immunoglobulin (IgG). The proposed amperometric biosensor was successfully used for determination of IgG in physiologic samples with excellent responses. (author)

  4. Meteorological and Land Surface Properties Impacting Sea Breeze Extent and Aerosol Distribution in a Dry Environment

    Science.gov (United States)

    Igel, Adele L.; van den Heever, Susan C.; Johnson, Jill S.

    2018-01-01

    The properties of sea breeze circulations are influenced by a variety of meteorological and geophysical factors that interact with one another. These circulations can redistribute aerosol particles and pollution and therefore can play an important role in local air quality, as well as impact remote sensing. In this study, we select 11 factors that have the potential to impact either the sea breeze circulation properties and/or the spatial distribution of aerosols. Simulations are run to identify which of the 11 factors have the largest influence on the sea breeze properties and aerosol concentrations and to subsequently understand the mean response of these variables to the selected factors. All simulations are designed to be representative of conditions in coastal sub tropical environments and are thus relatively dry, as such they do not support deep convection associated with the sea breeze front. For this dry sea breeze regime, we find that the background wind speed was the most influential factor for the sea breeze propagation, with the soil saturation fraction also being important. For the spatial aerosol distribution, the most important factors were the soil moisture, sea-air temperature difference, and the initial boundary layer height. The importance of these factors seems to be strongly tied to the development of the surface-based mixed layer both ahead of and behind the sea breeze front. This study highlights potential avenues for further research regarding sea breeze dynamics and the impact of sea breeze circulations on pollution dispersion and remote sensing algorithms.

  5. Formation and global distribution of sea-surface microlayers

    Directory of Open Access Journals (Sweden)

    O. Wurl

    2011-01-01

    Full Text Available Results from a study of surfactants in the sea-surface microlayer (SML in different regions of the ocean (subtropical, temperate, polar suggest that this interfacial layer between the ocean and atmosphere covers the ocean's surface to a significant extent. New, experimentally-derived threshold values at which primary production acts as a significant source of natural surfactants to the microlayer are coupled with a wind speed threshold at which the SML is presumed to be disrupted, and the results suggest that surfactant enrichment in the SML is greater in oligotrophic regions of the ocean than in more productive waters. Furthermore, surfactant enrichments persisted at wind speeds of up to 10 m s−1, without any observed depletion above 5 m s−1. This suggests that the SML is stable enough to exist even at the global average wind speed of 6.6 m s−1. Using our observations of the surfactant enrichments at various trophic levels and wind states, global maps of primary production and wind speed allow us to extrapolate the ocean's SML coverage . The maps indicate that wide regions of the Pacific and Atlantic Oceans between 30° N and 30° S may be more significantly covered with SML than north of 30° N and south of 30° S, where higher productivity (spring/summer blooms and wind speeds exceeding 12 m s−1 may prevent extensive SML formation.

  6. Electric potential distributions at the interface between plasmasheet clouds

    Science.gov (United States)

    Evans, D. S.; Roth, M.; Lemaire, J.

    1987-01-01

    At the interface between two plasma clouds with different densities, temperatures, and/or bulk velocities, there are large charge separation electric fields which can be modeled in the framework of a collisionless theory for tangential discontinuities. Two different classes of layers were identified: the first one corresponds to (stable) ion layers which are thicker than one ion Lamor radius; the second one corresponds to (unstable) electron layers which are only a few electron Larmor radii thick. It is suggested that these thin electron layers with large electric potential gradients (up to 400 mV/m) are the regions where large-amplitude electrostatic waves are spontaneously generated. These waves scatter the pitch angles of the ambient plasmasheet electron into the atmospheric loss cone. The unstable electron layers can therefore be considered as the seat of strong pitch angle scattering for the primary auroral electrons.

  7. Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during short static contractions at low force level

    NARCIS (Netherlands)

    Klaver-Krol, Ewa G.; Henriquez, Nizare R.; Oosterloo, Sebe J.; Klaver, Peter; Kuipers, Harm; Zwarts, Machiel J.

    2010-01-01

    In surface electromyography (sEMG), the distribution of motor unit potential (MUP) velocities has been shown to reflect the proportion of faster and slower propagating MUPs. This study investigated whether the distribution of MUP velocities could distinguish between sprinters and endurance athletes

  8. Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during prolonged dynamic exercises at low force levels

    NARCIS (Netherlands)

    Klaver-Krol, Ewa G.; Henriquez, Nizare R.; Oosterloo, Sebe J.; Klaver, Peter; Kuipers, Harm; Zwarts, Machiel J.

    2010-01-01

    In surface electromyography (sEMG), the distribution of motor unit potential (MUP) velocities has been shown to reflect the proportion of faster and slower propagating MUPs. This study investigated whether the distribution of MUP velocities could distinguish between sprinters (n = 11) and endurance

  9. Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during prolonged dynamic exercises at low force levels.

    NARCIS (Netherlands)

    Klaver-Krol, E.G.; Henriquez, N.R.; Oosterloo, S.J.; Klaver, P.; Kuipers, H.; Zwarts, M.J.

    2010-01-01

    In surface electromyography (sEMG), the distribution of motor unit potential (MUP) velocities has been shown to reflect the proportion of faster and slower propagating MUPs. This study investigated whether the distribution of MUP velocities could distinguish between sprinters (n=11) and endurance

  10. Deuterium (2H) Distribution in surface and groundwaters in Brazil

    International Nuclear Information System (INIS)

    Matsui, E.; Azevedo, C.T.

    1980-01-01

    Evaporation and condensation processes cause variation in the relative concentrations of hydrogen and oxygen isotopes. In the case of hydrogen, variations of the order of 350 0 /oo were observed in deuterium concentrations in natural waters. In heavy water production plants, wherever possible, water with high deuterium content should be used in the first stages of the enrichment process. Taking this into consideration, work was carried out on the systematic collection of samples from surface and groundwaters for the analysis of deuterium all over Brasil. Deuterium concentration values were obtained in 458 samples collected at different regions and at different times. This project was developed together with others of hydrological interest, the final objective of which was not to cover all characteristic regions of the country. (Author) [pt

  11. Surface photometry and mass distributions of spiral galaxies

    International Nuclear Information System (INIS)

    Blackman, C.P.

    1979-01-01

    U, B, V and R surface photometry is presented for the two luminosity class I-II galaxies NGC 1084 and 7331. The reduced profiles of both galaxies have well-defined outer components similar to that described in an earlier paper for NGC 157. The radial variation of M/L has been studied by extrapolating the observed rotation curves. The gross structure and detailed colour and M/L variations for both galaxies are described in terms of the density wave theory of spiral structure, which implies that the rotation curves are not flat at large radii. The outer components of both galaxies are too luminous to form conventional massive haloes. In both galaxies the total luminosity exceeds that expected from their luminosity class. (author)

  12. Massive calculations of electrostatic potentials and structure maps of biopolymers in a distributed computing environment

    International Nuclear Information System (INIS)

    Akishina, T.P.; Ivanov, V.V.; Stepanenko, V.A.

    2013-01-01

    Among the key factors determining the processes of transcription and translation are the distributions of the electrostatic potentials of DNA, RNA and proteins. Calculations of electrostatic distributions and structure maps of biopolymers on computers are time consuming and require large computational resources. We developed the procedures for organization of massive calculations of electrostatic potentials and structure maps for biopolymers in a distributed computing environment (several thousands of cores).

  13. Surface Activity Distributions of Comet 67P/Churyumov-Gerasimenko Derived from VIRTIS Images

    Science.gov (United States)

    Fougere, Nicolas; Combi, Michael R.; Tenishev, Valeriy; Migliorini, Alessandra; Bockelee-Morvan, Dominique; Fink, Uwe; Filacchione, Gianrico; Rinaldi, Giovanna; Capaccioni, Fabrizio; Toth, Gabor; Gombosi, T. I.; Hansen, Kenneth C.; Huang, Zhenguang; Shou, Yinsi; VIRTIS Team

    2017-10-01

    The outgassing mechanism of comets still remains a critical question to better understand these objects. The Rosetta mission gave some insight regarding the potential activity distribution from the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, Fougere et al. (2016, Astronomy & Astrophysics, Volume 588, id.A134, 11 pp and Monthly Notices of the Royal Astronomical Society, Volume 462, Issue Suppl_1, p.S156-S169) used a spherical harmonics inversion scheme with in-situ measurements from the ROSINA instrument to derive mapping of the broad distribution of potential activity at the surface of the nucleus. Marschall et al. (2016, Astronomy & Astrophysics, doi: 10.1051/0004-6361/201730849) based on the appearance of dust active areas suggested that the so-called “neck” region and regions with fractured cliffs and locally steep slopes show more activity than the rest of comet 67P’s nucleus. Using in situ ROSINA measurements from a distance makes it difficult to distinguish between these two scenarios because the fast expansion of the gas and large molecular mean free paths prevents distinguishing small outgassing features even when the spacecraft was in bound orbits within 10 km from the nucleus. In this paper, we present a similar numerical inversion approach using VIRTIS images, which should better probe the very inner coma of comet 67P and give more detailed information about the outgassing activity. Support from contracts JPL #1266314 and #1266313 from the US Rosetta Project and grant NNX14AG84G from the NASA Planetary Atmospheres Program are gratefully acknowledged.

  14. Past and present potential distribution of the Iberian Abies species: A phytogeographic approach using pollen data and species distribution models

    OpenAIRE

    López-Sáez, JA; Benito de Pando, B; Linares, JC; Nieto-Lugilde, D; López-Merino, L

    2010-01-01

    This is the accepted version of the following article: Alba-Sánchez, F., López-Sáez, J. A., Pando, B. B.-d., Linares, J. C., Nieto-Lugilde, D. and López-Merino, L. (2010), Past and present potential distribution of the Iberian Abies species: a phytogeographic approach using fossil pollen data and species distribution models. Diversity and Distributions, 16: 214–228, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/j.1472-4642.2010.00636.x/abstract. Aim -...

  15. Distribution of soil selenium in China is potentially controlled by deposition and volatilization?

    Science.gov (United States)

    Sun, Guo-Xin; Meharg, Andrew A.; Li, Gang; Chen, Zheng; Yang, Lei; Chen, Song-Can; Zhu, Yong-Guan

    2016-02-01

    Elucidating the environmental drivers of selenium (Se) spatial distribution in soils at a continental scale is essential to better understand it’s biogeochemical cycling to improve Se transfer into diets. Through modelling Se biogeochemistry in China we found that deposition and volatilization are key factors controlling distribution in surface soil, rather than bedrock-derived Se (balance in other terrestrial environments worldwide.

  16. The influence of spherical cavity surface charge distribution on the sequence of partial discharge events

    Energy Technology Data Exchange (ETDEWEB)

    Illias, Hazlee A [Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Chen, George; Lewin, Paul L, E-mail: h.illias@um.edu.my [Tony Davies High Voltage Laboratory, School of Electronics and Computer Science, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

    2011-06-22

    In this work, a model representing partial discharge (PD) behaviour of a spherical cavity within a homogeneous dielectric material has been developed to study the influence of cavity surface charge distribution on the electric field distribution in both the cavity and the material itself. The charge accumulation on the cavity surface after a PD event and charge movement along the cavity wall under the influence of electric field magnitude and direction has been found to affect the electric field distribution in the whole cavity and in the material. This in turn affects the likelihood of any subsequent PD activity in the cavity and the whole sequence of PD events. The model parameters influencing cavity surface charge distribution can be readily identified; they are the cavity surface conductivity, the inception field and the extinction field. Comparison of measurement and simulation results has been undertaken to validate the model.

  17. Effect of attenuation correction on surface amplitude distribution of wind waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    Some selected wave profiles recorded using a ship borne wave recorder are analysed to study the effect of attenuation correction on the distribution of the surface amplitudes. A new spectral width parameter is defined to account for wide band...

  18. Wegner Estimates for Some Random Operators with Anderson-type Surface Potentials

    Science.gov (United States)

    Kitagaki, Yoshihiko

    2010-03-01

    For Schrödinger operator with random potentials concentrated near a surface, Wegner-type estimates are proven by using the spectral averaging method of Combes, Hislop and Klopp. These estimates allow us to show the local regularity of the integrated density of surface states at the gap of the background periodic operator. Acoustic operator with random surface potentials is treated similarly.

  19. Optically pumped GaN vertical cavity surface emitting laser with high index-contrast nanoporous distributed Bragg reflector.

    Science.gov (United States)

    Lee, Seung-Min; Gong, Su-Hyun; Kang, Jin-Ho; Ebaid, Mohamed; Ryu, Sang-Wan; Cho, Yong-Hoon

    2015-05-04

    Laser operation of a GaN vertical cavity surface emitting laser (VCSEL) is demonstrated under optical pumping with a nanoporous distributed Bragg reflector (DBR). High reflectivity, approaching 100%, is obtained due to the high index-contrast of the nanoporous DBR. The VCSEL system exhibits low threshold power density due to the formation of high Q-factor cavity, which shows the potential of nanoporous medium for optical devices.

  20. Nuclear stimulated desorption as a potential tool for surface study

    International Nuclear Information System (INIS)

    Nir, Dror.

    1993-03-01

    The described research work constitutes a base for an experimental method to be implemented in the study of solid surfaces. Nuclear Stimulated Desorption (NSD) is a new mode of experimentation in thin film and surface physics. It Is based on the interplay between nuclear phenomena (reactions and spontaneous decays), and atomic - scale induced effects on surfaces and very thin films. One may distinguish between two generically different relationships between the two. First, the dynamics of the nuclear reaction -primarily the recoil of the nucleus - may effect the position of the atom or molecule containing it. Second, the nuclear reaction (or decay) may serve as an analytical indicator of the whereabouts of the atom, or molecule, in question. In nuclear stimulated desorption, both thee aspects combine in an essential way. Namely, one employs a series of two consecutive decays (normally weak decays or isomeric transition) . The first of these decays causes the nucleus to desorb from a surface onto which it had been placed; the second serves to determine the position of the daughter and thereby the characteristics of the primary desorption . The essential feature in NSD is that it occurs almost exclusively from the outermost surface layer. This is because we choose to work with nuclei whose recoil energy Is of the same order of magnitude of the binding energy of the atom to the surface . Furthermore, the desorption probability and its angular (and temporal) characteristics, depend on the features (topology, morphology) of its immediate neighborhood. This work describes experiments which were designed to give relevant, phenomenological information about the outgoing flux of the radioactive daughters (for specifically chosen nuclear species) , and in particular the magnitude of the flux, its time dependence and its charged state. In addition. the basic phenomena itself is being distinguished from competing processes (thermal desorption, in particular). We will now

  1. Investigating the time-dependent zeta potential of wood surfaces.

    Science.gov (United States)

    Muff, Livius F; Luxbacher, Thomas; Burgert, Ingo; Michen, Benjamin

    2018-05-15

    This work reports on streaming potential measurements through natural capillaries in wood and investigates the cause of a time-dependent zeta potential measured during the equilibration of wood cell-walls with an electrolyte solution. For the biomaterial, this equilibration phase takes several hours, which is much longer than for many other materials that have been characterized by electrokinetic measurements. During this equilibration phase the zeta potential magnitude is decaying due to two parallel mechanisms: (i) the swelling of the cell-wall which causes a dimensional change reducing the charge density at the capillary interface; (ii) the transport of ions from the electrolyte solution into the permeable cell-wall which alters the electrical potential at the interface by internal charge compensation. The obtained results demonstrate the importance of equilibration kinetics for an accurate determination of the zeta potential, especially for materials that interact strongly with the measurement electrolyte. Moreover, the change in zeta potential with time can be correlated with the bulk swelling of wood if the effect of electrolyte ion diffusion is excluded. This study shows the potential of streaming potential measurements of wood, and possibly of other hygroscopic and nanoporous materials, to reveal kinetic information about their interaction with liquids, such as swelling and ion uptake. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. Plant-soil distribution of potentially toxic elements in response to elevated atmospheric CO2.

    Science.gov (United States)

    Duval, Benjamin D; Dijkstra, Paul; Natali, Susan M; Megonigal, J Patrick; Ketterer, Michael E; Drake, Bert G; Lerdau, Manuel T; Gordon, Gwyneth; Anbar, Ariel D; Hungate, Bruce A

    2011-04-01

    The distribution of contaminant elements within ecosystems is an environmental concern because of these elements' potential toxicity to animals and plants and their ability to hinder microbial ecosystem services. As with nutrients, contaminants are cycled within and through ecosystems. Elevated atmospheric CO2 generally increases plant productivity and alters nutrient element cycling, but whether CO2 causes similar effects on the cycling of contaminant elements is unknown. Here we show that 11 years of experimental CO2 enrichment in a sandy soil with low organic matter content causes plants to accumulate contaminants in plant biomass, with declines in the extractable contaminant element pools in surface soils. These results indicate that CO2 alters the distribution of contaminant elements in ecosystems, with plant element accumulation and declining soil availability both likely explained by the CO2 stimulation of plant biomass. Our results highlight the interdependence of element cycles and the importance of taking a broad view of the periodic table when the effects of global environmental change on ecosystem biogeochemistry are considered.

  3. Angular distribution of sputtered atoms from Al-Sn alloy and surface topography

    International Nuclear Information System (INIS)

    Wang Zhenxia; Pan Jisheng; Zhang Jiping; Tao Zhenlan

    1992-01-01

    If an alloy is sputtered the angular distribution of the sputtered atoms can be different for each component. At high ion energies in the range of linear cascade theory, different energy distributions for components of different mass in the solid are predicted. Upon leaving the surface, i.e. overcoming the surface binding energy, these differences should show up in different angular distributions. Differences in the angular distribution are of much practical interest, for example, in thin-film deposition by sputtering and surface analysis by secondary-ion mass spectroscopy and Auger electron spectroscopy. Recently our experimental work has shown that for Fe-W alloy the surface microtopography becomes dominant and determines the shape of the angular distribution of the component. However, with the few experimental results available so far it is too early to draw any general conclusions for the angular distribution of the sputtered constituents. Thus, the aim of this work was to study further the influence of the surface topography on the shape of the angular distribution of sputtered atoms from an Al-Sn alloy. (Author)

  4. Potential energy surfaces for Ж = , Ne- Ba nuclei

    Indian Academy of Sciences (India)

    112Ba nu- clei in an axially deformed relativistic mean field approach. A quadratic constraint scheme is applied to determine the complete energy surface for a wide range of the quadrupole deformation. The NL3, NL-RA1 and TM1 parameter sets ...

  5. Earthquake Energy Distribution along the Earth Surface and Radius

    International Nuclear Information System (INIS)

    Varga, P.; Krumm, F.; Riguzzi, F.; Doglioni, C.; Suele, B.; Wang, K.; Panza, G.F.

    2010-07-01

    The global earthquake catalog of seismic events with M W ≥ 7.0, for the time interval from 1950 to 2007, shows that the depth distribution of earthquake energy release is not uniform. The 90% of the total earthquake energy budget is dissipated in the first ∼30km, whereas most of the residual budget is radiated at the lower boundary of the transition zone (410 km - 660 km), above the upper-lower mantle boundary. The upper border of the transition zone at around 410 km of depth is not marked by significant seismic energy release. This points for a non-dominant role of the slabs in the energy budged of plate tectonics. Earthquake number and energy release, although not well correlated, when analysed with respect to the latitude, show a decrease toward the polar areas. Moreover, the radiated energy has the highest peak close to (±5 o ) the so-called tectonic equator defined by Crespi et al. (2007), which is inclined about 30 o with respect to the geographic equator. At the same time the presence of a clear axial co- ordination of the radiated seismic energy is demonstrated with maxima at latitudes close to critical (±45 o ). This speaks about the presence of external forces that influence seismicity and it is consistent with the fact that Gutenberg-Richter law is linear, for events with M>5, only when the whole Earth's seismicity is considered. These data are consistent with an astronomical control on plate tectonics, i.e., the despinning (slowing of the Earth's angular rotation) of the Earth's rotation caused primarily by the tidal friction due to the Moon. The mutual position of the shallow and ∼660 km deep earthquake energy sources along subduction zones allows us to conclude that they are connected with the same slab along the W-directed subduction zones, but they may rather be disconnected along the opposed E-NE-directed slabs, being the deep seismicity controlled by other mechanisms. (author)

  6. Global Distribution and Variability of Surface Skin and Surface Air Temperatures as Depicted in the AIRS Version-6 Data Set

    Science.gov (United States)

    Susskind, Joel; Lee, Jae N.; Iredell, Lena

    2014-01-01

    In this presentation, we will briefly describe the significant improvements made in the AIRS Version-6 retrieval algorithm, especially as to how they affect retrieved surface skin and surface air temperatures. The global distribution of seasonal 1:30 AM and 1:30 PM local time 12 year climatologies of Ts,a will be presented for the first time. We will also present the spatial distribution of short term 12 year anomaly trends of Ts,a at 1:30 AM and 1:30 PM, as well as the spatial distribution of temporal correlations of Ts,a with the El Nino Index. It will be shown that there are significant differences between the behavior of 1:30 AM and 1:30 PM Ts,a anomalies in some arid land areas.

  7. Effect of potential attraction term on surface tension of ionic liquids

    Science.gov (United States)

    Vaziri, N.; Khordad, R.; Rezaei, G.

    2018-03-01

    In this work, we have studied the effect of attraction term of molecular potential on surface tension of ionic liquids (ILs). For this purpose, we have introduced two different potential models to obtain analytical expressions for the surface tension of ILs. The introduced potential models have different attraction terms. The obtained surface tensions in this work have been compared with other theoretical methods and also experimental data. Using the calculated surface tension, the sound velocity is also estimated. We have studied the structural effects on the surface tensions of imidazolium-based ionic liquids. It is found that the cation alkyl chain length and the anion size play important roles to the surface tension of the selected ionic liquids. The calculated surface tensions show a good harmony with experimental data. It is clear that the attraction term of molecular potential has an important role on surface tension and sound velocity of our system.

  8. Temperature distribution on the MEA surface of a PEMFC with serpentine channel flow bed

    Science.gov (United States)

    Wang, Maohai; Guo, Hang; Ma, Chongfang

    Knowledge of the temperature distribution on the membrane electrode assembly (MEA) surface and heat transfer processes inside a proton exchange membrane fuel cell (PEMFC) is helpful to improvement of cell reliability, durability and performance. The temperature fields on the surface of MEA fixed inside a proton exchange membrane fuel cell with a serpentine channel flow bed were measured by infrared imaging technology under non-humidification conditions. The temperature distributions over the MEA surface under whole channel region were achieved. The experimental results show that the downstream temperatures are higher than the upstream. The hot region on the MEA surface is easy to locate from the infrared temperature image. The mean temperature on the MEA surface and the cell temperature both increase with the current density. Higher current density makes the non-uniformity of temperature distribution on the MEA surface worse. The loading time significantly affects the temperature distribution. Compared with the electrical performance of the cell, the MEA's temperatures need much more time to reach stable. The results indicate that isothermal assumption is not appropriate for a modeling of PEMFCs, and monitoring the temperature of external surface of the flow field plate or end plate cannot supply accurate reference to control the temperatures on MEA surface.

  9. Dynamic measurement of surface strain distribution on the foot during walking.

    Science.gov (United States)

    Ito, Kohta; Maeda, Kosuke; Fujiwara, Ikumi; Hosoda, Koh; Nagura, Takeo; Lee, Taeyong; Ogihara, Naomichi

    2017-05-01

    To clarify the mechanism underlying the development of foot disorders such as diabetic ulcers and deformities, it is important to understand how the foot surface elongates and contracts during gait. Such information is also helpful for improving the prevention and treatment of foot disorders. We therefore measured temporal changes in the strain distribution on the foot surface during human walking. Five adult male participants walked across a glass platform placed over an angled mirror set in a wooden walkway at a self-selected speed and the dorsolateral and plantar surfaces of the foot were filmed using two pairs of synchronized high-speed cameras. Three-dimensional (3D) digital image correlation was used to quantify the spatial strain distribution on the foot surface with respect to that during quiet standing. Using the proposed method, we observed the 3D patterns of foot surface strain distribution during walking. Large strain was generated around the ball on the plantar surface of the foot throughout the entire stance phase, due to the windlass mechanism. The dorsal surface around the cuboid was stretched in the late stance phase, possibly due to lateral protruding movement of the cuboid. It may be possible to use this technique to non-invasively estimate movements of the foot bones under the skin using the surface strain distribution. The proposed technique may be an effective tool with which to analyze foot deformation in the fields of diabetology, clinical orthopedics, and ergonomics. Copyright © 2017. Published by Elsevier Ltd.

  10. Calibration of a distributed hydrology and land surface model using energy flux measurements

    DEFF Research Database (Denmark)

    Larsen, Morten Andreas Dahl; Refsgaard, Jens Christian; Jensen, Karsten H.

    2016-01-01

    In this study we develop and test a calibration approach on a spatially distributed groundwater-surface water catchment model (MIKE SHE) coupled to a land surface model component with particular focus on the water and energy fluxes. The model is calibrated against time series of eddy flux measure...

  11. Health risk implications of potentially toxic metals in street dust and surface soil of Tehran, Iran.

    Science.gov (United States)

    Dehghani, Sharareh; Moore, Farid; Keshavarzi, Behnam; Hale, Beverley A

    2017-02-01

    In this study a total of 30 street dusts and 10 surface soils were collected in the central district of Tehran and analyzed for major potentially toxic metals. Street dust was found to be greatly enriched in Sb, Pb, Cu and Zn and moderately enriched in Cr, Mn, Mo and Ni. Contamination of Cu, Sb, Pb and Zn was clearly related to anthropogenic sources such as brake wear, tire dust, road abrasion and fossil fuel combustion. Spatial distribution of pollution load index in street dust suggested that industries located south-west of the city intensify street dust pollution. Microscopic studies revealed six dominant group of morphological structures in calculation of the exposurethe street dusts and surface soils, with respect to different geogenic and anthropogenic sources. The BCR (the European Community Bureau of Reference) sequential extraction results showed that Sb, Ni, Mo, As and Cr bonded to silicates and sulfide minerals were highly resistant to dissolution. In contrast, Zn, Cd, and Mn were mostly associated with the exchangeable phase and thus would be easily mobilized in the environment. Cu was the most abundant metal in the reducible fraction, indicating its adsorption to iron and manganese oxy-hydroxides. Pb was equally extracted from exchangeable and reducible fractions. Anthropogenic sources related to traffic apparently play a small role in Cr, Ni and Mo contamination and dispersed them as bioavailable forms but with reduced mobility and bioavailablity due to high potential of complexation and adsorption to organic matter and iron and manganese oxy-hydroxides. Calculated Hazard Index (HI) suggests ingestion as the most important pathway for the majority of PTMs in children and dermal contact as the main exposure route for Cr, Cd and Sb for adults. The HIs and fractionation pattern of elements revealed Pb as the sole element that bears potential health risk in street dust and surface soil. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Mining for diagnostic information in body surface potential maps: A comparison of feature selection techniques

    Directory of Open Access Journals (Sweden)

    McCullagh Paul J

    2005-09-01

    that in this study recording sites have been suggested on their ability to detect disease and such sites may not be optimal for estimating body surface potential distributions.

  13. Direct molecular simulation of nitrogen dissociation based on an ab initio potential energy surface

    International Nuclear Information System (INIS)

    Valentini, Paolo; Schwartzentruber, Thomas E.; Bender, Jason D.; Nompelis, Ioannis; Candler, Graham V.

    2015-01-01

    The direct molecular simulation (DMS) approach is used to predict the internal energy relaxation and dissociation dynamics of high-temperature nitrogen. An ab initio potential energy surface (PES) is used to calculate the dynamics of two interacting nitrogen molecules by providing forces between the four atoms. In the near-equilibrium limit, it is shown that DMS reproduces the results obtained from well-established quasiclassical trajectory (QCT) analysis, verifying the validity of the approach. DMS is used to predict the vibrational relaxation time constant for N 2 –N 2 collisions and its temperature dependence, which are in close agreement with existing experiments and theory. Using both QCT and DMS with the same PES, we find that dissociation significantly depletes the upper vibrational energy levels. As a result, across a wide temperature range, the dissociation rate is found to be approximately 4–5 times lower compared to the rates computed using QCT with Boltzmann energy distributions. DMS calculations predict a quasi-steady-state distribution of rotational and vibrational energies in which the rate of depletion of high-energy states due to dissociation is balanced by their rate of repopulation due to collisional processes. The DMS approach simulates the evolution of internal energy distributions and their coupling to dissociation without the need to precompute rates or cross sections for all possible energy transitions. These benchmark results could be used to develop new computational fluid dynamics models for high-enthalpy flow applications

  14. Vertical changes in the probability distribution of downward irradiance within the near-surface ocean under sunny conditions

    Science.gov (United States)

    Gernez, Pierre; Stramski, Dariusz; Darecki, Miroslaw

    2011-07-01

    Time series measurements of fluctuations in underwater downward irradiance, Ed, within the green spectral band (532 nm) show that the probability distribution of instantaneous irradiance varies greatly as a function of depth within the near-surface ocean under sunny conditions. Because of intense light flashes caused by surface wave focusing, the near-surface probability distributions are highly skewed to the right and are heavy tailed. The coefficients of skewness and excess kurtosis at depths smaller than 1 m can exceed 3 and 20, respectively. We tested several probability models, such as lognormal, Gumbel, Fréchet, log-logistic, and Pareto, which are potentially suited to describe the highly skewed heavy-tailed distributions. We found that the models cannot approximate with consistently good accuracy the high irradiance values within the right tail of the experimental distribution where the probability of these values is less than 10%. This portion of the distribution corresponds approximately to light flashes with Ed > 1.5?, where ? is the time-averaged downward irradiance. However, the remaining part of the probability distribution covering all irradiance values smaller than the 90th percentile can be described with a reasonable accuracy (i.e., within 20%) with a lognormal model for all 86 measurements from the top 10 m of the ocean included in this analysis. As the intensity of irradiance fluctuations decreases with depth, the probability distribution tends toward a function symmetrical around the mean like the normal distribution. For the examined data set, the skewness and excess kurtosis assumed values very close to zero at a depth of about 10 m.

  15. Surface micro-distributions of pigment and the relation between smearing and local mass distribution

    International Nuclear Information System (INIS)

    Buelow, K.; Kristiansson, P.; Larsson, T.; Malmberg, S.; Elfman, M.; Malmqvist, K.; Pallon, J.; Shariff, A.

    2001-01-01

    In this work, the process of smearing and its time evolution have been investigated. When smearing occurs, the print is removed from the printed paper and colours other parts of the paper or the printing press and destroys the final product. To study the re-distribution of ink, cyan ink with Cu as a tracer in the coloured pigment has been used. Non-printed paper has been pressed against the paper, 1 and 5 s after the printing. The micro-distributions of ink on both printed and non-printed papers have then been studied using particle-induced X-ray emission (PIXE). Basis weight was measured with the off-axis scanning transmission ion microscopy (STIM) technique and this data was correlated with the data from the print. One conclusion is that the process of smearing is not dependent on the shape of the pigment distribution, i.e. copper, or the content of copper in a specific pixel. On the contrary, the smearing was found to be related to the structure of the paper and that it mainly occurs where the paper is thicker

  16. Ocular surface distribution and pharmacokinetics of a novel ophthalmic 1% azithromycin formulation.

    Science.gov (United States)

    Akpek, Esen Karamursel; Vittitow, Jason; Verhoeven, Rozemarijn S; Brubaker, Kurt; Amar, Thierry; Powell, Kendall D; Boyer, José L; Crean, Christopher

    2009-10-01

    To investigate the ocular distribution of 1% azithromycin ophthalmic solution and the effect of polycarbophil-based mucoadhesive formulation on ocular tissue levels of azithromycin after single and multiple topical administrations in the rabbit eye. Rabbits were treated with either a single administration of 1% azithromycin solution with or without polycarbophil, or with multiple administrations of 1% azithromycin solution in polycarbophil. Drug concentrations were measured using LC/MS/MS. Conjunctiva, cornea, aqueous humor, and tear samples were analyzed over a period of 144 h after a single administration of azithromycin with or without polycarbophil. Eyelid, conjunctiva, cornea, aqueous humor, and tear samples were collected over a period of 288 h during and after multiple administrations of azithromycin. Azithromycin was rapidly absorbed and distributed in the ocular tissues, reaching within 5 min, concentrations of 10,539 microg/mL in tear film, 108 microg/g in conjunctiva, and 40 microg/g in the cornea. The drug demonstrated tissue-specific half-lives of 15, 63, and 67 h, respectively. Following multiple administrations, the drug gradually accumulated. The polycarbophil formulation increased the bioavailability of the drug, producing peak concentrations that were between 5- and 12-fold higher than those without polycarbophil. Azithromycin also distributed rapidly in the eyelids, reaching peak concentrations of 180 mug/g at the end of the 7-day treatment, and was eliminated with a half-life of 125 h. Six days after treatment was discontinued, eyelid levels of azithromycin were above 40 microg/g. Sustained and high concentrations were encountered with 7-day approved administration of 1% azithromycin formulation (AzaSite, Inspire Pharmaceuticals, Inc., Durham, NC) within all ocular surface tissues, particularly the lids. Many ocular surface disorders involving the tear film, eyelids, and adnexal structures are associated with chronic, low-grade bacterial

  17. Surface potentials of (001), (012), (113) hematite (α-Fe2O3) crystal faces in aqueous solution.

    Science.gov (United States)

    Chatman, Shawn; Zarzycki, Piotr; Rosso, Kevin M

    2013-09-07

    Hematite (α-Fe2O3) is an important candidate electrode for energy system technologies such as photoelectrochemical water splitting. Conversion efficiency issues with this material are presently being addressed through nanostructuring, doping, and surface modification. However, key electrochemical properties of hematite/electrolyte interfaces remain poorly understood at a fundamental level, in particular those of crystallographically well-defined hematite faces likely present as interfacial components at the grain scale. We report a combined measurement and theory study that isolates and evaluates the equilibrium surface potentials of three nearly defect-free single crystal faces of hematite, titrated from pH 3 to 11.25. We link measured surface potentials with atomic-scale surface topology, namely the ratio and distributions of surface protonation-deprotonation site types expected from the bulk structure. The data reveal face-specific points of zero potential (PZP) relatable to points of zero net charge (PZC) that lie within a small pH window (8.35-8.85). Over the entire pH range the surface potentials show strong non-Nernstian charging at pH extremes separated by a wide central plateau in agreement with surface complexation modeling predictions, but with important face-specific distinctions. We introduce a new surface complexation model based on fitting the entire data set that depends primarily only on the proton affinities of two site types and the two associated electrical double layer capacitances. The data and model show that magnitudes of surface potential biases at the pH extremes are on the order of 100 mV, similar to the activation energy for electron hopping mobility. An energy band diagram for hematite crystallites with specific face expression and pH effects is proposed that could provide a baseline for understanding water splitting performance enhancement effects from nanostructuring, and guide morphology targets and pH for systematic improvements in

  18. Adsorption of lysozyme on base metal surfaces in the presence of an external electric potential.

    Science.gov (United States)

    Ei Ei, Htwe; Nakama, Yuhi; Tanaka, Hiroshi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi

    2016-11-01

    The impact of external electric potential on the adsorption of a protein to base metal surfaces was examined. Hen egg white lysozyme (LSZ) and six types of base metal plates (stainless steel SUS316L (St), Ti, Ta, Zr, Cr, or Ni) were used as the protein and adsorption surface, respectively. LSZ was allowed to adsorb on the surface under different conditions (surface potential, pH, electrolyte type and concentration, surface material), which was monitored using an ellipsometer. LSZ adsorption was minimized in the potential range above a certain threshold and, in the surface potential range below the threshold, decreasing the surface potential increased the amount of protein adsorbed. The threshold potential for LSZ adsorption was shifted toward a positive value with increasing pH and was lower for Ta and Zr than for the others. A divalent anion salt (K2SO4) as an electrolyte exhibited the adsorption of LSZ in the positive potential range while a monovalent salt (KCl) did not. A comprehensive consideration of the obtained results suggests that two modes of interactions, namely the electric force by an external electric field and electrostatic interactions with ionized surface hydroxyl groups, act on the LSZ molecules and determine the extent of suppression of LSZ adsorption. All these findings appear to support the view that a base metal surface can be controlled for the affinity to a protein by manipulating the surface electric potential as has been reported on some electrode materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Intensity distributions of reflected surface channeling protons scattered on surfaces of electron-bombarded alkali halide crystals

    Science.gov (United States)

    Fukazawa, Y.; Kihara, K.; Iwamoto, K.; Susuki, Y.

    2013-11-01

    We have examined the surface-channeling of 550 keV protons on electron-bombarded KBr(0 0 1) surfaces at grazing incidence. On the surface, electron-stimulated desorption (ESD) resulting from the irradiation of 5 keV electrons changes the surface morphology. In order to investigate the change of the surface morphology, the luminous intensity distributions observed on a fluorescent screen (scattering patterns) of the reflected protons under the surface-channeling conditions are measured. Normalized specular intensity of the protons oscillates, and the results of computer simulations show that the period of the intensity oscillation agrees with the period of layer-by-layer desorption. The measured period of the oscillation is comparable to the simulated one, i.e., the period of the desorption, however, the measured amplitude of the oscillation is weak. This shows that the layer-by-layer desorption of the experimental surface is observed but is not as remarkable as that of the perfect surface introduced in the simulation.

  20. Intensity distributions of reflected surface channeling protons scattered on surfaces of electron-bombarded alkali halide crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fukazawa, Y., E-mail: yukofu@cc.osaka-kyoiku.ac.jp; Kihara, K.; Iwamoto, K.; Susuki, Y.

    2013-11-15

    We have examined the surface-channeling of 550 keV protons on electron-bombarded KBr(0 0 1) surfaces at grazing incidence. On the surface, electron-stimulated desorption (ESD) resulting from the irradiation of 5 keV electrons changes the surface morphology. In order to investigate the change of the surface morphology, the luminous intensity distributions observed on a fluorescent screen (scattering patterns) of the reflected protons under the surface-channeling conditions are measured. Normalized specular intensity of the protons oscillates, and the results of computer simulations show that the period of the intensity oscillation agrees with the period of layer-by-layer desorption. The measured period of the oscillation is comparable to the simulated one, i.e., the period of the desorption, however, the measured amplitude of the oscillation is weak. This shows that the layer-by-layer desorption of the experimental surface is observed but is not as remarkable as that of the perfect surface introduced in the simulation.

  1. Sources and distribution of yttrium and rare earth elements in surface sediments from Tagus estuary, Portugal.

    Science.gov (United States)

    Brito, Pedro; Prego, Ricardo; Mil-Homens, Mário; Caçador, Isabel; Caetano, Miguel

    2018-04-15

    The distribution and sources of yttrium and rare-earth elements (YREE) in surface sediments were studied on 78 samples collected in the Tagus estuary (SW Portugal, SW Europe). Yttrium and total REE contents ranged from 2.4 to 32mg·kg -1 and 18 to 210mg·kg -1 , respectively, and exhibited significant correlations with sediment grain-size, Al, Fe, Mg and Mn, suggesting a preferential association to fine-grained material (e.g. aluminosilicates but also Al hydroxides and Fe oxyhydroxides). The PAAS (Post-Archean Australian Shale) normalized patterns display three distinct YREE fractionation pattern groups along the Tagus estuary: a first group, characterized by medium to coarse-grained material, a depleted and almost flat PAAS-normalized pattern, with a positive anomaly of Eu, representing one of the lithogenic components; a second group, characterized mainly by fine-grained sediment, with higher shale-normalized ratios and an enrichment of LREE relative to HREE, associated with waste water treatment plant (WWTP) outfalls, located in the northern margin; and, a third group, of fine-grained material, marked by a significant enrichment of Y, a depletion of Ce and an enrichment of HREE over LREE, located near an inactive chemical-industrial complex (e.g. pyrite roast plant, chemical and phosphorous fertilizer industries), in the southern margin. The data allow the quantification of the YREE contents and its spatial distribution in the surface sediments of the Tagus estuary, identifying the main potential sources and confirming the use of rare earth elements as tracers of anthropogenic activities in highly hydrodynamic estuaries. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Evaluation of Surface Water Harvesting Potential in Aq Emam Watershed System in the Golestan Province

    Directory of Open Access Journals (Sweden)

    s. nazaryan

    2016-02-01

    of runoff production potential indicated that May and June accounted for the highest runoff and it can be inferred from these results that both of these months are characterized with storms which was confirmed by interviewing local residents and as range-land covers the largest land use in the basin as well as low vegetation density in the spring and summer due to overgrazing, much more runoff has been produced which is in line with the studies conducted by the Department of Natural Resources of the Golestan province in Aq Emam watershed (2003 as well as findings of Eftekhari et al. The results showed that the highest areas of the sub watershed 8, and 3 were suitable for rain water harvesting. Thus, the appropriate areas for rain water harvesting in the sub watersheds do not have a uniform spatial distribution according to the results. It can be argued that these sub basins are characterized by 4 criteria to be appropriate for rain water harvesting, which is in confirmation with Miliniai et al. Also according to the results, the areas suitable for rainwater harvesting in each sub-basin have heterogeneous spatial distribution as confirmed by the results of Eftekhari and Jin et al. Given the final map from integrating data layers, it was found that the central part of the study area has a good potential for rainwater harvesting and as results show, suitable area for water harvesting in the watershed coincides with range-lands that have a moderate crown cover as confirmed by the results reported by Tabatabaii et al. Conclusion: Finally it can be said that spatial evaluation and identification of proper areas for rain water harvesting is an important and necessary step in the application of rain water harvesting systems. Keywords: Surface water harvesting, Spatial evaluation, Sub watersheds priority, GIS, SCS

  3. Calculation of the surface potential and surface charge density by measurement of the three-phase contact angle.

    Science.gov (United States)

    Horiuchi, H; Nikolov, A; Wasan, D T

    2012-11-01

    The silica/silicon wafer is widely used in the semiconductor industry in the manufacture of electronic devices, so it is essential to understand its physical chemistry and determine the surface potential at the silica wafer/water interface. However, it is difficult to measure the surface potential of a silica/silicon wafer directly due to its high electric resistance. In the present study, the three-phase contact angle (TPCA) on silica is measured as a function of the pH. The surface potential and surface charge density at the silica/water surface are calculated by a model based on the Young-Lippmann equation in conjunction with the Gouy-Chapman model for the electric double layer. In measurements of the TPCA on silica, two distinct regions were identified with a boundary at pH 9.5-showing a dominance of the surface ionization of silanol groups below pH 9.5 and a dominance of the dissolution of silica into the aqueous solution above pH 9.5. Since the surface chemistry changes above pH 9.5, the model is applied to solutions below pH 9.5 (ionization dominant) for the calculation of the surface potential and surface charge density at the silica/aqueous interface. In order to evaluate the model, a galvanic mica cell was made of a mica sheet and the surface potential was measured directly at the mica/water interface. The model results are also validated by experimental data from the literature, as well as the results obtained by the potentiometric titration method and the electro-kinetic measurements. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Oxathiiranes 8 On the OCS2 Singlet Potential Energy Surface

    DEFF Research Database (Denmark)

    Carlsen, Lars

    1982-01-01

    as the fragmentations of the possible intermediates 1–5 have been studied theoretically within the semiempirical cndo/B framework as conceivable ground-state reactions. On the basis of mo correlations and potential energy changes along the reaction paths, supplementary with previously reported experimental data...

  5. Beyond Massive MIMO: The Potential of Positioning With Large Intelligent Surfaces

    Science.gov (United States)

    Hu, Sha; Rusek, Fredrik; Edfors, Ove

    2018-04-01

    We consider the potential for positioning with a system where antenna arrays are deployed as a large intelligent surface (LIS), which is a newly proposed concept beyond massive-MIMO where future man-made structures are electronically active with integrated electronics and wireless communication making the entire environment \\lq\\lq{}intelligent\\rq\\rq{}. In a first step, we derive Fisher-information and Cram\\'{e}r-Rao lower bounds (CRLBs) in closed-form for positioning a terminal located perpendicular to the center of the LIS, whose location we refer to as being on the central perpendicular line (CPL) of the LIS. For a terminal that is not on the CPL, closed-form expressions of the Fisher-information and CRLB seem out of reach, and we alternatively find approximations of them which are shown to be accurate. Under mild conditions, we show that the CRLB for all three Cartesian dimensions ($x$, $y$ and $z$) decreases quadratically in the surface-area of the LIS, except for a terminal exactly on the CPL where the CRLB for the $z$-dimension (distance from the LIS) decreases linearly in the same. In a second step, we analyze the CRLB for positioning when there is an unknown phase $\\varphi$ presented in the analog circuits of the LIS. We then show that the CRLBs are dramatically increased for all three dimensions but decrease in the third-order of the surface-area. Moreover, with an infinitely large LIS the CRLB for the $z$-dimension with an unknown $\\varphi$ is 6 dB higher than the case without phase uncertainty, and the CRLB for estimating $\\varphi$ converges to a constant that is independent of the wavelength $\\lambda$. At last, we extensively discuss the impact of centralized and distributed deployments of LIS, and show that a distributed deployment of LIS can enlarge the coverage for terminal-positioning and improve the overall positioning performance.

  6. Quantum dynamical study of the O(1D)+HCl reaction employing three electronic state potential energy surfaces

    Science.gov (United States)

    Yang, Huan; Han, Ke-Li; Nanbu, Shinkoh; Nakamura, Hiroki; Balint-Kurti, Gabriel G.; Zhang, Hong; Smith, Sean C.; Hankel, Marlies

    2008-01-01

    Quantum dynamical calculations are reported for the title reaction, for both product arrangement channels and using potential energy surfaces corresponding to the three electronic states, 1A'1, 2A'1, and 1A″1, which correlate with both reactants and products. The calculations have been performed for J =0 using the time-dependent real wavepacket approach by Gray and Balint-Kurti [J. Chem. Phys. 108, 950 (1998)]. Reaction probabilities for both product arrangement channels on all three potential energy surfaces are presented for total energies between 0.1 and 1.1eV. Product vibrational state distributions at two total energies, 0.522 and 0.722eV, are also presented for both channels and all three electronic states. Product rotational quantum state distributions are presented for both product arrangement channels and all three electronic states for the first six product vibrational states.

  7. Calculation of surface potentials at the silica-water interface using molecular dynamics: Challenges and opportunities

    Science.gov (United States)

    Lowe, Benjamin M.; Skylaris, Chris-Kriton; Green, Nicolas G.; Shibuta, Yasushi; Sakata, Toshiya

    2018-04-01

    Continuum-based methods are important in calculating electrostatic properties of interfacial systems such as the electric field and surface potential but are incapable of providing sufficient insight into a range of fundamentally and technologically important phenomena which occur at atomistic length-scales. In this work a molecular dynamics methodology is presented for interfacial electric field and potential calculations. The silica-water interface was chosen as an example system, which is highly relevant for understanding the response of field-effect transistors sensors (FET sensors). Detailed validation work is presented, followed by the simulated surface charge/surface potential relationship. This showed good agreement with experiment at low surface charge density but at high surface charge density the results highlighted challenges presented by an atomistic definition of the surface potential. This methodology will be used to investigate the effect of surface morphology and biomolecule addition; both factors which are challenging using conventional continuum models.

  8. An accurate global potential energy surface, dipole moment surface, and rovibrational frequencies for NH3

    Science.gov (United States)

    Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

    2008-12-01

    A global potential energy surface (PES) that includes short and long range terms has been determined for the NH3 molecule. The singles and doubles coupled-cluster method that includes a perturbational estimate of connected triple excitations and the internally contracted averaged coupled-pair functional electronic structure methods have been used in conjunction with very large correlation-consistent basis sets, including diffuse functions. Extrapolation to the one-particle basis set limit was performed and core correlation and scalar relativistic contributions were included directly, while the diagonal Born-Oppenheimer correction was added. Our best purely ab initio PES, denoted "mixed," is constructed from two PESs which differ in whether the ic-ACPF higher-order correlation correction was added or not. Rovibrational transition energies computed from the mixed PES agree well with experiment and the best previous theoretical studies, but most importantly the quality does not deteriorate even up to 10300cm-1 above the zero-point energy (ZPE). The mixed PES was improved further by empirical refinement using the most reliable J =0-2 rovibrational transitions in the HITRAN 2004 database. Agreement between high-resolution experiment and rovibrational transition energies computed from our refined PES for J =0-6 is excellent. Indeed, the root mean square (rms) error for 13 HITRAN 2004 bands for J =0-2 is 0.023cm-1 and that for each band is always ⩽0.06cm-1. For J =3-5 the rms error is always ⩽0.15cm-1. This agreement means that transition energies computed with our refined PES should be useful in the assignment of new high-resolution NH3 spectra and in correcting mistakes in previous assignments. Ideas for further improvements to our refined PES and for extension to other isotopolog are discussed.

  9. Influence of surface conductivity on the apparent zeta potential of calcite.

    Science.gov (United States)

    Li, Shuai; Leroy, Philippe; Heberling, Frank; Devau, Nicolas; Jougnot, Damien; Chiaberge, Christophe

    2016-04-15

    Zeta potential is a physicochemical parameter of particular importance in describing the surface electrical properties of charged porous media. However, the zeta potential of calcite is still poorly known because of the difficulty to interpret streaming potential experiments. The Helmholtz-Smoluchowski (HS) equation is widely used to estimate the apparent zeta potential from these experiments. However, this equation neglects the influence of surface conductivity on streaming potential. We present streaming potential and electrical conductivity measurements on a calcite powder in contact with an aqueous NaCl electrolyte. Our streaming potential model corrects the apparent zeta potential of calcite by accounting for the influence of surface conductivity and flow regime. We show that the HS equation seriously underestimates the zeta potential of calcite, particularly when the electrolyte is diluted (ionic strength ⩽ 0.01 M) because of calcite surface conductivity. The basic Stern model successfully predicted the corrected zeta potential by assuming that the zeta potential is located at the outer Helmholtz plane, i.e. without considering a stagnant diffuse layer at the calcite-water interface. The surface conductivity of calcite crystals was inferred from electrical conductivity measurements and computed using our basic Stern model. Surface conductivity was also successfully predicted by our surface complexation model. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Analysis of Large Array Surface Myoelectric Potentials for the Low Back Muscles

    National Research Council Canada - National Science Library

    Reger, Steven

    2001-01-01

    .... The surface EMC distribution from the low back of 161 healthy and 44 acute LBP subjects were collected in three minimum stress postural positions including standing, 20 degrees of lumbar flexion...

  11. Sexual differentiation in the distribution potential of northern jaguars (Panthera onca)

    Science.gov (United States)

    Erin E. Boydston; Carlos A. Lopez Gonzalez

    2005-01-01

    We estimated the potential geographic distribution of jaguars in the southwestern United States and northwestern Mexico by modeling the jaguar ecological niche from occurrence records. We modeled separately the distributions of males and females, assuming records of females probably represented established home ranges while male records likely included dispersal...

  12. Potential surface for the collinear collision of Ne and H/sub 2//sup +/. [eendoergicity, surface parametrization

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, E.F.; Siu, A.K.Q.; Chapman, F.M. Jr.; Matcha, R.L.

    1976-09-01

    A potential energy surface for the Ne--H/sub 2//sup +/ reaction has been obtained in the LCAO--MO--SCF approximation. Analysis of the surface indicates that the reaction Ne+H/sub 2//sup +/..-->..NeH/sup +/+H should proceed with an endoergicity of 12 kcal/mole, in agreement with the experimental results of Chupka and Russell. Several procedures for parameterizing a diatomics-in-molecules (DIM) representation of the NeH/sub 2//sup +/ surface are considered. The results show that an accurate representation of the SCF surface can be obtained from the DIM model using a minimum of diatomic and triatomic data. (AIP)

  13. Climate change and the potential distribution of an invasive shrub, Lantana camara L.

    Science.gov (United States)

    Taylor, Subhashni; Kumar, Lalit; Reid, Nick; Kriticos, Darren J

    2012-01-01

    The threat posed by invasive species, in particular weeds, to biodiversity may be exacerbated by climate change. Lantana camara L. (lantana) is a woody shrub that is highly invasive in many countries of the world. It has a profound economic and environmental impact worldwide, including Australia. Knowledge of the likely potential distribution of this invasive species under current and future climate will be useful in planning better strategies to manage the invasion. A process-oriented niche model of L. camara was developed using CLIMEX to estimate its potential distribution under current and future climate scenarios. The model was calibrated using data from several knowledge domains, including phenological observations and geographic distribution records. The potential distribution of lantana under historical climate exceeded the current distribution in some areas of the world, notably Africa and Asia. Under future scenarios, the climatically suitable areas for L. camara globally were projected to contract. However, some areas were identified in North Africa, Europe and Australia that may become climatically suitable under future climates. In South Africa and China, its potential distribution could expand further inland. These results can inform strategic planning by biosecurity agencies, identifying areas to target for eradication or containment. Distribution maps of risk of potential invasion can be useful tools in public awareness campaigns, especially in countries that have been identified as becoming climatically suitable for L. camara under the future climate scenarios.

  14. Climate change and the potential distribution of an invasive shrub, Lantana camara L.

    Directory of Open Access Journals (Sweden)

    Subhashni Taylor

    Full Text Available The threat posed by invasive species, in particular weeds, to biodiversity may be exacerbated by climate change. Lantana camara L. (lantana is a woody shrub that is highly invasive in many countries of the world. It has a profound economic and environmental impact worldwide, including Australia. Knowledge of the likely potential distribution of this invasive species under current and future climate will be useful in planning better strategies to manage the invasion. A process-oriented niche model of L. camara was developed using CLIMEX to estimate its potential distribution under current and future climate scenarios. The model was calibrated using data from several knowledge domains, including phenological observations and geographic distribution records. The potential distribution of lantana under historical climate exceeded the current distribution in some areas of the world, notably Africa and Asia. Under future scenarios, the climatically suitable areas for L. camara globally were projected to contract. However, some areas were identified in North Africa, Europe and Australia that may become climatically suitable under future climates. In South Africa and China, its potential distribution could expand further inland. These results can inform strategic planning by biosecurity agencies, identifying areas to target for eradication or containment. Distribution maps of risk of potential invasion can be useful tools in public awareness campaigns, especially in countries that have been identified as becoming climatically suitable for L. camara under the future climate scenarios.

  15. VBORNET Gap Analysis: Sand Fly Vector Distribution Models Utilised to Identify Areas of Potential Species Distribution in Areas Lacking Records

    Directory of Open Access Journals (Sweden)

    Bulent Alten

    2016-12-01

    Full Text Available This is the first of a number of planned data papers presenting modelled vector distributions, the models in this paper were produced during the ECDC funded VBORNET project. This work continues under the VectorNet project now jointly funded by ECDC and EFSA. This data paper contains the sand fly model outputs produced as part of the VBORNET project. Further data papers will be published after sampling seasons when more field data will become available allowing further species to be modelled or validation and updates to existing models. The data package described here includes those sand fly species first modelled in 2013 and 2014 as part of the VBORNET gap analysis work which aimed to identify areas of potential species distribution in areas lacking records. It comprises four species models together with suitability masks based on land class and environmental limits. The species included within this paper are 'Phlebotomus ariasi', 'Phlebotomus papatasi', 'Phlebotomus perniciosus' and 'Phlebotomus tobbi'. The known distributions of these species within the project area (Europe, the Mediterranean Basin, North Africa, and Eurasia are currently incomplete to a greater or lesser degree. The models are designed to fill the gaps with predicted distributions, to provide a assistance in targeting surveys to collect ­distribution data for those areas with no field validated information, and b a first indication of project wide distributions.

  16. VBORNET gap analysis: Mosquito vector distribution models utilised to identify areas of potential species distribution in areas lacking records.

    Directory of Open Access Journals (Sweden)

    Francis Schaffner

    2016-12-01

    Full Text Available This is the second of a number of planned data papers presenting modelled vector distributions produced originally during the ECDC funded VBORNET project. This work continues under the VectorNet project now jointly funded by ECDC and EFSA. Further data papers will be published after sampling seasons when more field data will become available allowing further species to be modelled or validation and updates to existing models.  The data package described here includes those mosquito species first modelled in 2013 & 2014 as part of the VBORNET gap analysis work which aimed to identify areas of potential species distribution in areas lacking records. It comprises three species models together with suitability masks based on land class and environmental limits. The species included as part of this phase are the mosquitoes 'Aedes vexans', 'Anopheles plumbeus' and 'Culex modestus'. The known distributions of these species within the area covered by the project (Europe, the ­Mediterranean Basin, North Africa, and Eurasia are currently incomplete to a greater or lesser degree. The models are designed to fill the gaps with predicted distributions, to provide a assistance in ­targeting surveys to collect distribution data for those areas with no field validated information, and b a first indication of the species distributions within the project areas.

  17. Measuring agglomerate size distribution and dependence of localized surface plasmon resonance absorbance on gold nanoparticle agglomerate size using analytical ultracentrifugation.

    Science.gov (United States)

    Zook, Justin M; Rastogi, Vinayak; Maccuspie, Robert I; Keene, Athena M; Fagan, Jeffrey

    2011-10-25

    Agglomeration of nanoparticles during measurements in relevant biological and environmental media is a frequent problem in nanomaterial property characterization. The primary problem is typically that any changes to the size distribution can dramatically affect the potential nanotoxicity or other size-determined properties, such as the absorbance signal in a biosensor measurement. Herein we demonstrate analytical ultracentrifugation (AUC) as a powerful method for measuring two critical characteristics of nanoparticle (NP) agglomerates in situ in biological media: the NP agglomerate size distribution, and the localized surface plasmon resonance (LSPR) absorbance spectrum of precise sizes of gold NP agglomerates. To characterize the size distribution, we present a theoretical framework for calculating the hydrodynamic diameter distribution of NP agglomerates from their sedimentation coefficient distribution. We measure sedimentation rates for monomers, dimers, and trimers, as well as for larger agglomerates with up to 600 NPs. The AUC size distributions were found generally to be broader than the size distributions estimated from dynamic light scattering and diffusion-limited colloidal aggregation theory, an alternative bulk measurement method that relies on several assumptions. In addition, the measured sedimentation coefficients can be used in nanotoxicity studies to predict how quickly the agglomerates sediment out of solution under normal gravitational forces, such as in the environment. We also calculate the absorbance spectra for monomer, dimer, trimer, and larger gold NP agglomerates up to 600 NPs, to enable a better understanding of LSPR biosensors. Finally, we validate a new method that uses these spectra to deconvolute the net absorbance spectrum of an unknown bulk sample and approximate the proportions of monomers, dimers, and trimers in a polydisperse sample of small agglomerates, so that every sample does not need to be measured by AUC. These results

  18. Electrohydrodynamics of binary electrolytes driven by modulated surface potentials

    DEFF Research Database (Denmark)

    Mortensen, Asger; Olesen, Laurits Højgaard; Belmon, L.

    2005-01-01

    We study the electrohydrodynamics of the Debye screening layer that arises in an aqueous binary solution near a planar insulating wall when applying a spatially modulated ac voltage. Combining this with first order perturbation theory we establish the governing equations for the full nonequilibrium...... problem and obtain analytic solutions in the bulk for the pressure and velocity fields of the electrolyte and for the electric potential. We find good agreement between the numerics of the full problem and the analytics of the linear theory. Our work provides the theoretical foundations of circuit models...

  19. Intermolecular potential energy surface and thermophysical properties of ethylene oxide

    International Nuclear Information System (INIS)

    Crusius, Johann-Philipp; Hassel, Egon; Hellmann, Robert; Bich, Eckard

    2014-01-01

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C 2 H 4 O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide

  20. Intermolecular potential energy surface and thermophysical properties of ethylene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Crusius, Johann-Philipp, E-mail: johann-philipp.crusius@uni-rostock.de; Hassel, Egon [Lehrstuhl für Technische Thermodynamik, Universität Rostock, 18059 Rostock (Germany); Hellmann, Robert; Bich, Eckard [Institut für Chemie, Universität Rostock, 18059 Rostock (Germany)

    2014-10-28

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C{sub 2}H{sub 4}O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.

  1. Oxygen Distribution and Potential Ammonia Oxidation in Floating, Liquid Manure Crusts

    DEFF Research Database (Denmark)

    Nielsen, Daniel Aagren; Nielsen, Lars Peter; Schramm, Andreas

    2010-01-01

     availability. In old natural crusts total potential NH3 oxidation rates were similar to reported fluxes of NH3 from slurry without surface crust. These results indicate that old, natural surface crusts may develop into a porous matrix with high O2 availability that harbors an active population of aerobic...

  2. Ab Initio and DFT Potential Energy Surfaces for Cyanuric Chloride Reactions

    National Research Council Canada - National Science Library

    Pai, Sharmila

    1998-01-01

    ... on the potential energy surface were calculated using the 6-31G and 6-311 +Gbasis sets. DFT(B3LYP) geometry optimizations and zero-point corrections for critical points on the potential energy surface were calculated with the 6-31G, 6-311...

  3. 3D Printed Potential and Free Energy Surfaces for Teaching Fundamental Concepts in Physical Chemistry

    Science.gov (United States)

    Kaliakin, Danil S.; Zaari, Ryan R.; Varganov, Sergey A.

    2015-01-01

    Teaching fundamental physical chemistry concepts such as the potential energy surface, transition state, and reaction path is a challenging task. The traditionally used oversimplified 2D representation of potential and free energy surfaces makes this task even more difficult and often confuses students. We show how this 2D representation can be…

  4. An accurate potential energy surface for the F + H2 → HF + H reaction by the coupled-cluster method.

    Science.gov (United States)

    Chen, Jun; Sun, Zhigang; Zhang, Dong H

    2015-01-14

    A three dimensional potential energy surface for the F + H2 → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2)Q] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H2 reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface.

  5. Prediction of hydrocarbon surface seepage potential using infiltrometer data

    Science.gov (United States)

    Connors, J. J.; Jackson, J. L.; Engle, R. A.; Connors, J. L.

    2017-12-01

    Environmental regulations addressing above-ground storage tank (AST) spill control activities typically require owners/operators to demonstrate that local soil permeability values are low enough to adequately contain released liquids while emergency-response procedures are conducted. Frequently, geotechnical borings and soil samples/analyses, and/or monitoring well slug-test analyses, are used to provide hydraulic conductivity data for the required calculations. While these techniques are useful in assessing hydrological characteristics of the subsurface, they do not always assess the uppermost surface soil layer, where the bulk of the containment can occur. This layer may have been subject to long-term permeability-reduction by activities such as compaction by vehicular and foot traffic, micro-coatings by hydrophobic pollutants, etc. This presentation explores the usefulness of dual-ring infiltrometers, both in field and bench-scale tests, to rapidly acquire actual hydraulic conductivity values of surficial soil layers, which can be much lower than subsurface values determined using more traditional downhole geotechnical and hydrogeological approaches.

  6. Probability distribution for the Gaussian curvature of the zero level surface of a random function

    Science.gov (United States)

    Hannay, J. H.

    2018-04-01

    A rather natural construction for a smooth random surface in space is the level surface of value zero, or ‘nodal’ surface f(x,y,z)  =  0, of a (real) random function f; the interface between positive and negative regions of the function. A physically significant local attribute at a point of a curved surface is its Gaussian curvature (the product of its principal curvatures) because, when integrated over the surface it gives the Euler characteristic. Here the probability distribution for the Gaussian curvature at a random point on the nodal surface f  =  0 is calculated for a statistically homogeneous (‘stationary’) and isotropic zero mean Gaussian random function f. Capitalizing on the isotropy, a ‘fixer’ device for axes supplies the probability distribution directly as a multiple integral. Its evaluation yields an explicit algebraic function with a simple average. Indeed, this average Gaussian curvature has long been known. For a non-zero level surface instead of the nodal one, the probability distribution is not fully tractable, but is supplied as an integral expression.

  7. Effects of surface active agents on DNAPL migration and distribution in saturated porous media.

    Science.gov (United States)

    Cheng, Zhou; Gao, Bin; Xu, Hongxia; Sun, Yuanyuan; Shi, Xiaoqing; Wu, Jichun

    2016-11-15

    Dissolved surface active agents such as surfactant and natural organic matter can affect the distribution and fate of dense nonaqueous liquids (DNAPLs) in soil and groundwater systems. This work investigated how two common groundwater surface active agents, humic acid (HA) and Tween 80, affected tetrachloroethylene (PCE) migration and source zone architecture in saturated porous media under environmentally relevant conditions. Batch experiments were first conducted to measure the contact angles and interfacial tensions (IFT) between PCE and quartz surface in water containing different amount of surface active agents. Results showed that the contact angle increased and IFT decreased with concentration of surface active agent increasing, and Tween 80 was much more effective than HA. Five 2-D flow cell experiments were then conducted. Correspondingly, Tween 80 showed strong effects on the migration and distribution of PCE in the porous media due to its ability to change the medium wettability from water-wet into intermediate/NAPL-wet. The downward migration velocities of the PCE in three Tween 80 cells were slower than those in the other two cells. In addition, the final saturation of the PCE in the cells containing surface active agents was higher than that in the water-only cell. Results from this work indicate that the presence of surface active agents in groundwater may strongly affect the fate and distribution of DNAPL through altering porous medium wettability. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Dissociative chemisorption of methane on Ni(111) using a chemically accurate fifteen dimensional potential energy surface.

    Science.gov (United States)

    Zhou, Xueyao; Nattino, Francesco; Zhang, Yaolong; Chen, Jun; Kroes, Geert-Jan; Guo, Hua; Jiang, Bin

    2017-11-22

    A fifteen-dimensional global potential energy surface for the dissociative chemisorption of methane on the rigid Ni(111) surface is developed by a high fidelity fit of ∼200 000 DFT energy points computed using a specific reaction parameter density functional designed to reproduce experimental data. The permutation symmetry and surface periodicity are rigorously enforced using the permutation invariant polynomial-neural network approach. The fitting accuracy of the potential energy surface is thoroughly investigated by examining both static and dynamical attributes of CHD 3 dissociation on the frozen surface. This potential energy surface is expected to be chemically accurate as after correction for surface temperature effects it reproduces the measured initial sticking probabilities of CHD 3 on Ni(111) for various incidence conditions.

  9. Distribution and Characteristics of Boulder Halos at High Latitudes on Mars: Ground Ice and Surface Processes Drive Surface Reworking

    Science.gov (United States)

    Levy, J. S.; Fassett, C. I.; Rader, L. X.; King, I. R.; Chaffey, P. M.; Wagoner, C. M.; Hanlon, A. E.; Watters, J. L.; Kreslavsky, M. A.; Holt, J. W.; Russell, A. T.; Dyar, M. D.

    2018-02-01

    Boulder halos are circular arrangements of clasts present at Martian middle to high latitudes. Boulder halos are thought to result from impacts into a boulder-poor surficial unit that is rich in ground ice and/or sediments and that is underlain by a competent substrate. In this model, boulders are excavated by impacts and remain at the surface as the crater degrades. To determine the distribution of boulder halos and to evaluate mechanisms for their formation, we searched for boulder halos over 4,188 High Resolution Imaging Science Experiment images located between 50-80° north and 50-80° south latitude. We evaluate geological and climatological parameters at halo sites. Boulder halos are about three times more common in the northern hemisphere than in the southern hemisphere (19% versus 6% of images) and have size-frequency distributions suggesting recent Amazonian formation (tens to hundreds of millions of years). In the north, boulder halo sites are characterized by abundant shallow subsurface ice and high thermal inertia. Spatial patterns of halo distribution indicate that excavation of boulders from beneath nonboulder-bearing substrates is necessary for the formation of boulder halos, but that alone is not sufficient. Rather, surface processes either promote boulder halo preservation in the north or destroy boulder halos in the south. Notably, boulder halos predate the most recent period of near-surface ice emplacement on Mars and persist at the surface atop mobile regolith. The lifetime of observed boulders at the Martian surface is greater than the lifetime of the craters that excavated them. Finally, larger minimum boulder halo sizes in the north indicate thicker icy soil layers on average throughout climate variations driven by spin/orbit changes during the last tens to hundreds of millions of years.

  10. The Transit-Time Distribution from the Northern Hemisphere Midlatitude Surface

    Science.gov (United States)

    Orbe, Clara; Waugh, Darryn W.; Newman, Paul A.; Strahan, Susan; Steenrod, Stephen

    2015-01-01

    The distribution of transit times from the Northern Hemisphere (NH) midlatitude surface is a fundamental property of tropospheric transport. Here we present an analysis of the transit time distribution (TTD) since air last contacted the northern midlatitude surface layer, as simulated by the NASA Global Modeling Initiative Chemistry Transport Model. We find that throughout the troposphere the TTD is characterized by long flat tails that reflect the recirculation of old air from the Southern Hemisphere and results in mean ages that are significantly larger than the modal age. Key aspects of the TTD -- its mode, mean and spectral width -- are interpreted in terms of tropospheric dynamics, including seasonal shifts in the location and strength of tropical convection and variations in quasi-isentropic transport out of the northern midlatitude surface layer. Our results indicate that current diagnostics of tropospheric transport are insufficient for comparing model transport and that the full distribution of transit times is a more appropriate constraint.

  11. Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Wei [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial distribution is strongly dependent on bulk concentration. We show that this is due to the strong binding constant of hydronium H3O+ to the phosphate group, leading to proton-transfer back to the phosphate group and to a reduced surface charge. Using anomalous reflectivity off and at the L3 Cs+ resonance, we provide spatial counterion (Cs+) distributions next to the negatively charged interfaces. The experimental ion distributions are in excellent agreement with a renormalized surface charge Poisson-Boltzmann theory for monovalent ions without fitting parameters or additional assumptions. Energy Scans at four fixed momentum transfers under specular reflectivity conditions near the Cs+ L3 resonance were conducted on 10-3 M CsI with DHDP monolayer materials on the surface. The energy scans exhibit a periodic dependence on photon momentum transfer. The ion distributions obtained from the analysis are in excellent agreement with those obtained from anomalous reflectivity measurements, providing further confirmation to the validity of the renormalized surface charge Poisson-Boltzmann theory for monovalent ions. Moreover, the dispersion corrections f0 and f00 for Cs+ around L3 resonance, revealing the local environment of a Cs+ ion in the solution at the interface, were extracted simultaneously with output of ion distributions.

  12. Method for estimating potential tree-grade distributions for northeastern forest species

    Science.gov (United States)

    Daniel A. Yaussy; Daniel A. Yaussy

    1993-01-01

    Generalized logistic regression was used to distribute trees into four potential tree grades for 20 northeastern species groups. The potential tree grade is defined as the tree grade based on the length and amount of clear cuttings and defects only, disregarding minimum grading diameter. The algorithms described use site index and tree diameter as the predictive...

  13. Occurrence and Distribution of Organophosphate Esters in Surface Soil and Street Dust from Chongqing, China: Implications for Human Exposure.

    Science.gov (United States)

    He, Ming-Jing; Yang, Ting; Yang, Zhi-Hao; Li, Qi; Wei, Shi-Qiang

    2017-10-01

    In the present study, the occurrence, concentrations, and distribution of organophosphate esters (OPEs) were studied in surface soil and street dust samples collected from different sites of Chongqing, a metropolitan city in western China. Furthermore, nondietary daily intakes (DIs) of OPEs only through dust ingestion absorption were assessed between toddlers and adults. The ∑OPEs contents ranged from 10.1 to 315 ng/g dw and from 348 to 1369 ng/g dw in surface soil and street dust samples, respectively, with tris (2-butoxyethyl) phosphate (TBOEP), the predominant OPEs in surface soil, whereas tris (chloroethyl) phosphate (TCEP) occupied a relatively high proportion in street dust samples. The mobility of TCEP and tris (2-chloroisopropyl) phosphate (TCIPP) to deeper soil zones with seepage water may play a role in decreasing contents of both compounds in surface soil. Considerably different patterns of pairwise correlations of six OPEs congeners were observed between surface soil and street dust, which could largely relate to the complicated environmental process for tris (1,3-dichloroisopropyl) phosphate (TDCIPP) and TCIPP in surface soil. Analogous sources between surface soil and street dust have been identified through principal component analysis. Compared with adults, the toddlers were more vulnerable to OPEs intake, according to the estimated DI values. For both toddler and adult groups, the estimated exposure values for all OPEs were several orders of magnitude lower than the reference dose (RfD), not suggesting the potential risk to human health.

  14. Dynamic modeling method of the bolted joint with uneven distribution of joint surface pressure

    Science.gov (United States)

    Li, Shichao; Gao, Hongli; Liu, Qi; Liu, Bokai

    2018-03-01

    The dynamic characteristics of the bolted joints have a significant influence on the dynamic characteristics of the machine tool. Therefore, establishing a reasonable bolted joint dynamics model is helpful to improve the accuracy of machine tool dynamics model. Because the pressure distribution on the joint surface is uneven under the concentrated force of bolts, a dynamic modeling method based on the uneven pressure distribution of the joint surface is presented in this paper to improve the dynamic modeling accuracy of the machine tool. The analytic formulas between the normal, tangential stiffness per unit area and the surface pressure on the joint surface can be deduced based on the Hertz contact theory, and the pressure distribution on the joint surface can be obtained by the finite element software. Futhermore, the normal and tangential stiffness distribution on the joint surface can be obtained by the analytic formula and the pressure distribution on the joint surface, and assigning it into the finite element model of the joint. Qualitatively compared the theoretical mode shapes and the experimental mode shapes, as well as quantitatively compared the theoretical modal frequencies and the experimental modal frequencies. The comparison results show that the relative error between the first four-order theoretical modal frequencies and the first four-order experimental modal frequencies is 0.2% to 4.2%. Besides, the first four-order theoretical mode shapes and the first four-order experimental mode shapes are similar and one-to-one correspondence. Therefore, the validity of the theoretical model is verified. The dynamic modeling method proposed in this paper can provide a theoretical basis for the accurate dynamic modeling of the bolted joint in machine tools.

  15. Patterns of distribution of phosphomono-esterases on surfaces of demineralized bone

    DEFF Research Database (Denmark)

    Kirkeby, S; Vilmann, H

    1979-01-01

    Decalcification over short periods (5 days) with MnNa2 EDTA, MgNa2 EDTA and EGTA according to a method described in the present paper, creates sections of high quality with simultaneous good preservation of phosphomonoesterases on bone surfaces. In fact, the enzyme distribution seems to be compar......Decalcification over short periods (5 days) with MnNa2 EDTA, MgNa2 EDTA and EGTA according to a method described in the present paper, creates sections of high quality with simultaneous good preservation of phosphomonoesterases on bone surfaces. In fact, the enzyme distribution seems...... be an indication of differential processes of bone transformations in such a way that bone surfaces corresponding to areas of enzyme reactions are depository whereas bone surfaces corresponding to areas of lack of enzyme reaction are resorptive. New experimental designs are, however, necessary before...

  16. A numerical method for calculation of electrostatic charge distribution induced on conducting surfaces

    OpenAIRE

    Saeed Hatamzadeh-Varmazyar; Zahra Masouri

    2014-01-01

    The focus of this article is on calculation of electrostatic charge distribution induced on conducting surfaces. For this purpose, the integral equation concept is used for mathematical modeling of the problem. A special set of exponential basis functions is introduced and defined to be used in formulation of a numerical method for solving the integral equation to obtain the charge distribution. The method is numerically evaluated via calculation of charge density for some structures by which...

  17. Imaging the potential distribution of individual charged impurities on graphene by low-energy electron holography.

    Science.gov (United States)

    Latychevskaia, Tatiana; Wicki, Flavio; Escher, Conrad; Fink, Hans-Werner

    2017-11-01

    While imaging individual atoms can routinely be achieved in high resolution transmission electron microscopy, visualizing the potential distribution of individually charged adsorbates leading to a phase shift of the probing electron wave is still a challenging task. Low-energy electrons (30 - 250 eV) are sensitive to localized potential gradients. We employed low-energy electron holography to acquire in-line holograms of individual charged impurities on free-standing graphene. By applying an iterative phase retrieval reconstruction routine we recover the potential distribution of the localized charged impurities present on free-standing graphene. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Stable Flocking of Multiple Agents Based on Molecular Potential Field and Distributed Receding Horizon Control

    International Nuclear Information System (INIS)

    Zhang Yun-Peng; Duan Hai-Bin; Zhang Xiang-Yin

    2011-01-01

    A novel distributed control scheme to generate stable flocking motion for a group of agents is proposed. In this control scheme, a molecular potential field model is applied as the potential field function because of its smoothness and unique shape. The approach of distributed receding horizon control is adopted to drive each agent to find its optimal control input to lower its potential at every step. Experimental results show that this proposed control scheme can ensure that all agents eventually converge to a stable flocking formation with a common velocity and the collisions can also be avoided at the same time. (general)

  19. N-Terminal Plasmodium vivax Merozoite Surface Protein-1, a Potential Subunit for Malaria Vivax Vaccine

    Directory of Open Access Journals (Sweden)

    Fernanda G. Versiani

    2013-01-01

    Full Text Available The human malaria is widely distributed in the Middle East, Asia, the western Pacific, and Central and South America. Plasmodium vivax started to have the attention of many researchers since it is causing diseases to millions of people and several reports of severe malaria cases have been noticed in the last few years. The lack of in vitro cultures for P. vivax represents a major delay in developing a functional malaria vaccine. One of the major candidates to antimalarial vaccine is the merozoite surface protein-1 (MSP1, which is expressed abundantly on the merozoite surface and capable of activating the host protective immunity. Studies have shown that MSP-1 possesses highly immunogenic fragments, capable of generating immune response and protection in natural infection in endemic regions. This paper shows humoral immune response to different proteins of PvMSP1 and the statement of N-terminal to be added to the list of potential candidates for malaria vivax vaccine.

  20. Mapping current and potential distribution of non-native Prosopis juliflora in the Afar region of Ethiopia

    Science.gov (United States)

    Wakie, Tewodros; Evangelista, Paul H.; Jarnevich, Catherine S.; Laituri, Melinda

    2014-01-01

    We used correlative models with species occurrence points, Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices, and topo-climatic predictors to map the current distribution and potential habitat of invasive Prosopis juliflora in Afar, Ethiopia. Time-series of MODIS Enhanced Vegetation Indices (EVI) and Normalized Difference Vegetation Indices (NDVI) with 250 m2 spatial resolution were selected as remote sensing predictors for mapping distributions, while WorldClim bioclimatic products and generated topographic variables from the Shuttle Radar Topography Mission product (SRTM) were used to predict potential infestations. We ran Maxent models using non-correlated variables and the 143 species-occurrence points. Maxent generated probability surfaces were converted into binary maps using the 10-percentile logistic threshold values. Performances of models were evaluated using area under the receiver-operating characteristic (ROC) curve (AUC). Our results indicate that the extent of P. juliflora invasion is approximately 3,605 km2 in the Afar region (AUC = 0.94), while the potential habitat for future infestations is 5,024 km2 (AUC = 0.95). Our analyses demonstrate that time-series of MODIS vegetation indices and species occurrence points can be used with Maxent modeling software to map the current distribution of P. juliflora, while topo-climatic variables are good predictors of potential habitat in Ethiopia. Our results can quantify current and future infestations, and inform management and policy decisions for containing P. juliflora. Our methods can also be replicated for managing invasive species in other East African countries.

  1. Research on social communication network evolution based on topology potential distribution

    Science.gov (United States)

    Zhao, Dongjie; Jiang, Jian; Li, Deyi; Zhang, Haisu; Chen, Guisheng

    2011-12-01

    Aiming at the problem of social communication network evolution, first, topology potential is introduced to measure the local influence among nodes in networks. Second, from the perspective of topology potential distribution the method of network evolution description based on topology potential distribution is presented, which takes the artificial intelligence with uncertainty as basic theory and local influence among nodes as essentiality. Then, a social communication network is constructed by enron email dataset, the method presented is used to analyze the characteristic of the social communication network evolution and some useful conclusions are got, implying that the method is effective, which shows that topology potential distribution can effectively describe the characteristic of sociology and detect the local changes in social communication network.

  2. An experimental study of the surface elevation probability distribution and statistics of wind-generated waves

    Science.gov (United States)

    Huang, N. E.; Long, S. R.

    1980-01-01

    Laboratory experiments were performed to measure the surface elevation probability density function and associated statistical properties for a wind-generated wave field. The laboratory data along with some limited field data were compared. The statistical properties of the surface elevation were processed for comparison with the results derived from the Longuet-Higgins (1963) theory. It is found that, even for the highly non-Gaussian cases, the distribution function proposed by Longuet-Higgins still gives good approximations.

  3. Potential Release of Manufactured Nano Objects During Sanding of Nano-Coated Wood Surfaces.

    Science.gov (United States)

    Fransman, Wouter; Bekker, Cindy; Tromp, Peter; Duis, Willem B

    2016-08-01

    Increasing production and applications of manufactured nano objects (MNOs) have become a source for human exposure and therefore raise concerns and questions about the possible health effects. In this study, the potential release of nano objects, their agglomerates, and aggregates (NOAA) as a result of sanding of hardwood treated with MNOs-containing coating was examined. Two types of MNO-containing coating were compared with untreated hardwood that allowed the evaluation of the influence of the chemical composition on the release of particles. Furthermore, the rotation speed of the sander and the grit size of the sanding paper were varied in order to assess their influence on the release of particles.Measurements were conducted in a gas-tight chamber with a volume of 19.5 m(3) in which ventilation was minimized during experiments. Particle size distributions were assessed by scanning mobility particle sizer , aerodynamic particle sizer, and electrical low pressure impactor. Furthermore, aerosol number concentrations (Nanotracer), active surface area (LQ1), and fractionated mass (Cascade Impactor) were measured before, during, and after sanding. Scanning electron microscope/energy dispersive X-ray (SEM/EDX) analysis was performed to adequately characterize the morphology, size, and chemical composition of released particles.SEM/EDX analysis indicated that sanding surfaces treated with MNO-containing coating did not release the designated MNO as free primary particles. In both coatings, clusters of MNO were perceived embedded in and attached to micro-sized wood and/or coating particles created by sanding the coated surface. Real-time measurements indicated a lower release of micro-sized particles from sanding of surfaces treated with Coating I than from sanding untreated surfaces or surfaces treated with Coating II. A substantial increase in nanosized and a slight increase in micro-sized particles was perceived as the rotation speed of the sander increased. However

  4. Ab initio potential energy and dipole moment surfaces for CS2: determination of molecular vibrational energies.

    Science.gov (United States)

    Pradhan, Ekadashi; Carreón-Macedo, José-Luis; Cuervo, Javier E; Schröder, Markus; Brown, Alex

    2013-08-15

    The ground state potential energy and dipole moment surfaces for CS2 have been determined at the CASPT2/C:cc-pVTZ,S:aug-cc-pV(T+d)Z level of theory. The potential energy surface has been fit to a sum-of-products form using the neural network method with exponential neurons. A generic interface between neural network potential energy surface fitting and the Heidelberg MCTDH software package is demonstrated. The potential energy surface has also been fit using the potfit procedure in MCTDH. For fits to the low-energy regions of the potential, the neural network method requires fewer parameters than potfit to achieve high accuracy; global fits are comparable between the two methods. Using these potential energy surfaces, the vibrational energies have been computed for the four most abundant CS2 isotopomers. These results are compared to experimental and previous theoretical data. The current potential energy surfaces are shown to accurately reproduce the low-lying vibrational energies within a few wavenumbers. Hence, the potential energy and dipole moments surfaces will be useful for future study on the control of quantum dynamics in CS2.

  5. Geographic conditions for distribution of agriculture and potentials for tourism development on Mokra mountain

    Directory of Open Access Journals (Sweden)

    Knežević Marko

    2009-01-01

    Full Text Available This work considers important natural conditions of distribution of agricultural production, cattle breeding in particular, and also potentials for tourism development on Mokra mountain. Half-nomadic cattle breeding in mountain settlements was highly developed in recent past. It represented the main source of existence for local highlanders. Today it is neglected and in phase of dying out. The mountain disposes with excellent natural potentials for ecological and mountain tourism, but these potentials are unused.

  6. Interaction of landscape varibles on the potential geographical distribution of parrots in the Yucatan Peninsula, Mexico

    Directory of Open Access Journals (Sweden)

    Plasencia–Vázquez, A. H.

    2014-12-01

    Full Text Available The loss, degradation, and fragmentation of forested areas are endangering parrot populations. In this study, we determined the influence of fragmentation in relation to vegetation cover, land use, and spatial configuration of fragments on the potential geographical distribution patterns of parrots in the Yucatan Peninsula, Mexico. We used the potential geographical distribution for eight parrot species, considering the recently published maps obtained with the maximum entropy algorithm, and we incorporated the probability distribution for each species. We calculated 71 metrics/variables that evaluate forest fragmentation, spatial configuration of fragments, the ratio occupied by vegetation, and the land use in 100 plots of approximately 29 km², randomly distributed within the presence and absence areas predicted for each species. We also considered the relationship between environmental variables and the distribution probability of species. We used a partial least squares regression to explore patterns between the variables used and the potential distribution models. None of the environmental variables analyzed alone determined the presence/absence or the probability distribution of parrots in the Peninsula. We found that for the eight species, either due to the presence/absence or the probability distribution, the most important explanatory variables were the interaction among three variables, particularly the interactions among the total forest area, the total edge, and the tropical semi–evergreen medium– height forest. Habitat fragmentation influenced the potential geographical distribution of these species in terms of the characteristics of other environmental factors that are expressed together with the geographical division, such as the different vegetation cover ratio and land uses in deforested areas.

  7. Discrete cilia modelling with singularity distributions: application to the embryonic node and the airway surface liquid.

    Science.gov (United States)

    Smith, D J; Gaffney, E A; Blake, J R

    2007-07-01

    We discuss in detail techniques for modelling flows due to finite and infinite arrays of beating cilia. An efficient technique, based on concepts from previous 'singularity models' is described, that is accurate in both near and far-fields. Cilia are modelled as curved slender ellipsoidal bodies by distributing Stokeslet and potential source dipole singularities along their centrelines, leading to an integral equation that can be solved using a simple and efficient discretisation. The computed velocity on the cilium surface is found to compare favourably with the boundary condition. We then present results for two topics of current interest in biology. 1) We present the first theoretical results showing the mechanism by which rotating embryonic nodal cilia produce a leftward flow by a 'posterior tilt,' and track particle motion in an array of three simulated nodal cilia. We find that, contrary to recent suggestions, there is no continuous layer of negative fluid transport close to the ciliated boundary. The mean leftward particle transport is found to be just over 1 mum/s, within experimentally measured ranges. We also discuss the accuracy of models that represent the action of cilia by steady rotlet arrays, in particular, confirming the importance of image systems in the boundary in establishing the far-field fluid transport. Future modelling may lead to understanding of the mechanisms by which morphogen gradients or mechanosensing cilia convert a directional flow to asymmetric gene expression. 2) We develop a more complex and detailed model of flow patterns in the periciliary layer of the airway surface liquid. Our results confirm that shear flow of the mucous layer drives a significant volume of periciliary liquid in the direction of mucus transport even during the recovery stroke of the cilia. Finally, we discuss the advantages and disadvantages of the singularity technique and outline future theoretical and experimental developments required to apply this

  8. Biofilm formation in surface and drinking water distribution systems in Mafikeng, South Africa

    Directory of Open Access Journals (Sweden)

    Suma George Mulamattathil

    2014-11-01

    Full Text Available Poor quality source water and poorly treated reused wastewater may result in poor quality drinking water that has a higher potential to form biofilms. A biofilm is a group of microorganisms which adhere to a surface. We investigated biofilm growth in the drinking water distribution systems in the Mafikeng area, in the North- West Province of South Africa. Analysis was conducted to determine the presence of faecal coliforms, total coliforms, Pseudomonas spp. and Aeromonas spp. in the biofilms. Biofilms were grown on a device that contained copper and galvanised steel coupons. A mini tap filter – a point-of-use treatment device which can be used at a single faucet – was also used to collect samples. Scanning electron microscopy demonstrated that multi-species biofilms developed on all the coupons as well as on the point-of-use filters. Galvanised steel and carbon filters had the highest density of biofilm. Total coliforms, faecal coliforms and Pseudomonas spp. were isolated from raw water biofilm coupons only. Aeromonas spp. and Pseudomonas spp. were isolated from filters. The susceptibility of selected isolates was tested against 11 antibiotics of clinical interest. The most prevalent antibiotic resistance phenotype observed was KF-AP-C-E-OT-K-TM-A. The presence of virulence genes was determined using the polymerase chain reaction. These results indicate that bacteria present in the water have the ability to colonise as biofilms and drinking water biofilms may be a reservoir for opportunistic bacteria including Pseudomonas and Aeromonas species.

  9. 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

  10. Sensitivity Analysis of CLIMEX Parameters in Modeling Potential Distribution of Phoenix dactylifera L.

    Science.gov (United States)

    Shabani, Farzin; Kumar, Lalit

    2014-01-01

    Using CLIMEX and the Taguchi Method, a process-based niche model was developed to estimate potential distributions of Phoenix dactylifera L. (date palm), an economically important crop in many counties. Development of the model was based on both its native and invasive distribution and validation was carried out in terms of its extensive distribution in Iran. To identify model parameters having greatest influence on distribution of date palm, a sensitivity analysis was carried out. Changes in suitability were established by mapping of regions where the estimated distribution changed with parameter alterations. This facilitated the assessment of certain areas in Iran where parameter modifications impacted the most, particularly in relation to suitable and highly suitable locations. Parameter sensitivities were also evaluated by the calculation of area changes within the suitable and highly suitable categories. The low temperature limit (DV2), high temperature limit (DV3), upper optimal temperature (SM2) and high soil moisture limit (SM3) had the greatest impact on sensitivity, while other parameters showed relatively less sensitivity or were insensitive to change. For an accurate fit in species distribution models, highly sensitive parameters require more extensive research and data collection methods. Results of this study demonstrate a more cost effective method for developing date palm distribution models, an integral element in species management, and may prove useful for streamlining requirements for data collection in potential distribution modeling for other species as well. PMID:24722140

  11. Sensitivity analysis of CLIMEX parameters in modeling potential distribution of Phoenix dactylifera L.

    Directory of Open Access Journals (Sweden)

    Farzin Shabani

    Full Text Available Using CLIMEX and the Taguchi Method, a process-based niche model was developed to estimate potential distributions of Phoenix dactylifera L. (date palm, an economically important crop in many counties. Development of the model was based on both its native and invasive distribution and validation was carried out in terms of its extensive distribution in Iran. To identify model parameters having greatest influence on distribution of date palm, a sensitivity analysis was carried out. Changes in suitability were established by mapping of regions where the estimated distribution changed with parameter alterations. This facilitated the assessment of certain areas in Iran where parameter modifications impacted the most, particularly in relation to suitable and highly suitable locations. Parameter sensitivities were also evaluated by the calculation of area changes within the suitable and highly suitable categories. The low temperature limit (DV2, high temperature limit (DV3, upper optimal temperature (SM2 and high soil moisture limit (SM3 had the greatest impact on sensitivity, while other parameters showed relatively less sensitivity or were insensitive to change. For an accurate fit in species distribution models, highly sensitive parameters require more extensive research and data collection methods. Results of this study demonstrate a more cost effective method for developing date palm distribution models, an integral element in species management, and may prove useful for streamlining requirements for data collection in potential distribution modeling for other species as well.

  12. Multispectral UV imaging for surface analysis of MUPS tablets with special focus on the pellet distribution

    DEFF Research Database (Denmark)

    Novikova, Anna; Carstensen, Jens Michael; Rades, Thomas

    2016-01-01

    In the present study the applicability of multispectral UV imaging in combination with multivariate image analysis for surface evaluation of MUPS tablets was investigated with respect to the differentiation of the API pellets from the excipients matrix, estimation of the drug content as well...... on the tablet surface allowed an estimation of the true drug content in the respective MUPS tablet. In addition, the pellet distribution in the MUPS formulations could be estimated by UV image analysis of the tablet surface. In conclusion, this study revealed that UV imaging in combination with multivariate...... image analysis is a promising approach for the automatic quality control of MUPS tablets during the manufacturing process....

  13. Potential sputtering from a Si surface by very highly charged ion impact

    International Nuclear Information System (INIS)

    Tona, Masahide; Watanabe, Hirofumi; Takahashi, Satoshi; Nakamura, Nobuyuki; Yoshiyasu, Nobuo; Sakurai, Makoto; Yamada, Chikashi; Ohtani, Shunsuke

    2007-01-01

    We have observed radiation effect in collision of slow highly charged ions with the following target materials; a SiO 2 thin film, a Si(1 1 1)-(7 x 7) surface and a hydrogen terminated Si(1 1 1)-(1 x 1) surface. Secondary ion mass spectrometry and scanning tunneling microscopy revealed some features due to 'potential sputtering'; (a) strong dependence of secondary particle emission on the surface condition, (b) high yield of positive ion emission including cluster fragments and (c) creation of nanometer sized surface structure. The mechanism for the potential sputtering is briefly discussed, based on the 'Coulomb explosion' model

  14. The stochastic distribution of available coefficient of friction for human locomotion of five different floor surfaces.

    Science.gov (United States)

    Chang, Wen-Ruey; Matz, Simon; Chang, Chien-Chi

    2014-05-01

    The maximum coefficient of friction that can be supported at the shoe and floor interface without a slip is usually called the available coefficient of friction (ACOF) for human locomotion. The probability of a slip could be estimated using a statistical model by comparing the ACOF with the required coefficient of friction (RCOF), assuming that both coefficients have stochastic distributions. An investigation of the stochastic distributions of the ACOF of five different floor surfaces under dry, water and glycerol conditions is presented in this paper. One hundred friction measurements were performed on each floor surface under each surface condition. The Kolmogorov-Smirnov goodness-of-fit test was used to determine if the distribution of the ACOF was a good fit with the normal, log-normal and Weibull distributions. The results indicated that the ACOF distributions had a slightly better match with the normal and log-normal distributions than with the Weibull in only three out of 15 cases with a statistical significance. The results are far more complex than what had heretofore been published and different scenarios could emerge. Since the ACOF is compared with the RCOF for the estimate of slip probability, the distribution of the ACOF in seven cases could be considered a constant for this purpose when the ACOF is much lower or higher than the RCOF. A few cases could be represented by a normal distribution for practical reasons based on their skewness and kurtosis values without a statistical significance. No representation could be found in three cases out of 15. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  15. Sensitivity of Distributions of Climate System Properties to Surface Temperature Datasets

    Science.gov (United States)

    Libardoni, A. G.; Forest, C. E.

    2011-12-01

    Predictions of climate change from models depend strongly on the representation of climate system properties emerging from the processes and feedbacks in the models. The quality of any model prediction can be evaluated by determining how well its output reproduces the observed climate system. With this evaluation, the reliability of climate projections derived from the model and provided for policy makers is assessed and quantified. In this study, surface temperature, upper-air temperature, and ocean heat content data are used to constrain the distributions of the parameters that define three climate system properties in the MIT Integrated Global Systems Model: climate sensitivity, the rate of ocean heat uptake into the deep ocean, and net anthropogenic aerosol forcing. In particular, we explore the sensitivity of the distributions to the surface temperature dataset used to estimate the likelihood of model output given the observed climate records. In total, five different reconstructions of past surface temperatures are used and the resulting parameter distribution functions differ from each other. Differences in estimates of climate sensitivity mode and mean are as great as 1 K between the datasets, with an overall range of 1.2 to 5.3 K using the 5-95 confidence intervals. Ocean effective diffusivity is poorly constrained regardless of which dataset is used. All distributions show broad distributions and only three show signs of a distribution mode. When a mode is present, they tend to be for low diffusivity values. Distributions for the net aerosol forcing show similar shapes and cluster into two groups that are shifted by approximately 0.1 watts per square meter. However, the overall spread of forcing values from the 5-95 confidence interval, -0.19 to -0.83 watts per square meter, is small compared to other uncertainties in climate forcings. Transient climate response estimates derived from these distributions range between 0.87 and 2.41 K. Similar to the

  16. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering.

    Science.gov (United States)

    Schreck, Simon; Pietzsch, Annette; Kennedy, Brian; Såthe, Conny; Miedema, Piter S; Techert, Simone; Strocov, Vladimir N; Schmitt, Thorsten; Hennies, Franz; Rubensson, Jan-Erik; Föhlisch, Alexander

    2016-01-29

    Thermally driven chemistry as well as materials' functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.

  17. The impact of oxic degradation on long chain alkyl diol distributions in Arabian Sea surface sediments

    NARCIS (Netherlands)

    Rodrigo-Gámiz, M.; Rampen, S.W.; Schouten, S.; Sinninghe Damsté, J.S.

    2016-01-01

    Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affectthe application of organic proxies used for reconstructing past environmental conditions. To determineits effect on long chain alkyl diol and keto-ol based proxies, the distributions of these lipids

  18. The impact of oxic degradation on long chain alkyl diol distributions in Arabian Sea surface sediments

    NARCIS (Netherlands)

    Rodrigo-Gámiz, M.; Rampen, Sebastiaan W.; Schouten, S.; Sinninghe Damsté, J.S.

    2016-01-01

    Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affect the application of organic proxies used for reconstructing past environmental conditions. To determine its effect on long chain alkyl diol and keto-ol based proxies, the distributions of these

  19. High-resolution pattern of mangrove species distribution is controlled by surface elevation

    Science.gov (United States)

    Leong, Rick C.; Friess, Daniel A.; Crase, Beth; Lee, Wei Kit; Webb, Edward L.

    2018-03-01

    Mangrove vegetation species respond to multiple environmental gradients, and an enhanced understanding of how mangrove species are distributed across these gradients will facilitate conservation and management. Many environmental gradients correlate with tidal inundation; however small-scale inundation patterns resulting from microtopographical changes are difficult to capture empirically. In contrast, surface elevation is often a suitable, measurable and cost-effective proxy for inundation. This study investigated the relationships between species distribution and surface elevation in a mangrove forest in northwest Singapore. Through high-resolution land surveying, we developed a digital elevation model (DEM) and conducted a comprehensive survey of 4380 trees with a stem diameter ≥ 5 cm. A total of 15 species were encountered, and elevation envelopes were generated for 12. Species envelopes were distributed along an elevation continuum, with most species overlapping within the continuum. Spatial autocorrelation (SAC) was present for nine of the 15 species, and when taken into account, species ordering was modified across the elevation continuum. The presence of SAC strongly reinforces the need for research to control for SAC: classical spatial description of mangrove species distribution should be revised to account for ecological factors. This study suggests that (1) surface elevation applies strong controls on species distribution and (2) most mangroves at our study site have similar physiological tolerances.

  20. Potentiating the antibacterial effect of silver nanospheres by surface-capping with chlorhexidine gluconate

    Energy Technology Data Exchange (ETDEWEB)

    Priyadarshini, Balasankar Meera; Fawzy, Amr S., E-mail: denasfmf@nus.edu.sg [National University of Singapore, Discipline of Oral Sciences, Faculty of Dentistry (Singapore)

    2017-04-15

    In this work, the commercial polyvinylpyrrolidone (PVP)-capped silver nanospheres (Ag-NSP) were surface decorated with chlorhexidine gluconate (CHXg) for potentiating the antibacterial properties of Ag-NSP. Different formulations of CHXg-loaded Ag-NSP (Ag-NSP/CHXg) were prepared by varying the incubation times (0.5, 1.5, and 3 h). A thorough characterization of Ag-NSP/CHXg nanospheres has been carried out by dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive surface elemental composition spectral analysis (SEM/EDX), Fourier transform infrared spectroscopy (FTIR), percentage (%) CHXg loading efficiency (LE), in vitro CHXg and Ag{sup +} ion release, antibacterial/biofilm inhibition assay, and human mesenchymal stem cells (hMSCs) cytotoxicity evaluation. DLS measured nanospheres to be <160 nm and indicated that CHXg treatment drastically shifted the surface charge from negative to high positive values, with homogenous distribution. TEM revealed spherical Ag-NSP/CHXg nanospheres with a clearly visible surface coating of CHXg. FTIR confirmed association of CHXg with Ag-NSP nanospheres, whereas SEM/EDX data verified presence of spectral peaks specific to silver (Ag), CHXg, and PVP. The %LE gradually increased with increasing incubation times. In vitro CHXg release exhibited a bi-phasic fashion showing maximum release of ~74.83 ± 20.67% from Ag-NSP/CHXg-3h at 14 days. A slow release of Ag{sup +} ions was detected; however, the surface decoration of Ag-NSP substantially hampered/restricted the liberation of ions. Agar well diffusion, MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl) -2H–tetrazolium), and crystal violet assay suggested good antibacterial/antibiofilm activity of Ag-NSP/CHXg that correlated with the increasing %LE of nanospheres. hMSCs cytotoxicity study showed low toxicity properties of all nanosphere formulations, except for Ag-NSP/CHXg-3h, affecting the cell viability at all

  1. Unraveling the size distributions of surface properties for purple soil and yellow soil.

    Science.gov (United States)

    Tang, Ying; Li, Hang; Liu, Xinmin; Zhu, Hualing; Tian, Rui

    2015-06-01

    Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges (i.e. >10, 1-10, 0.5-1, 0.2-0.5 and soil (Entisol) and a yellow soil (Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction. We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles (soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy. Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties. Copyright © 2015. Published by Elsevier B.V.

  2. Distributed approximating functional fit of the H3 ab initio potential-energy data of Liu and Siegbahn

    International Nuclear Information System (INIS)

    Frishman, A.; Hoffman, D.K.; Kouri, D.J.

    1997-01-01

    We report a distributed approximating functional (DAF) fit of the ab initio potential-energy data of Liu [J. Chem. Phys. 58, 1925 (1973)] and Siegbahn and Liu [ibid. 68, 2457 (1978)]. The DAF-fit procedure is based on a variational principle, and is systematic and general. Only two adjustable parameters occur in the DAF leading to a fit which is both accurate (to the level inherent in the input data; RMS error of 0.2765 kcal/mol) and smooth (open-quotes well-tempered,close quotes in DAF terminology). In addition, the LSTH surface of Truhlar and Horowitz based on this same data [J. Chem. Phys. 68, 2466 (1978)] is itself approximated using only the values of the LSTH surface on the same grid coordinate points as the ab initio data, and the same DAF parameters. The purpose of this exercise is to demonstrate that the DAF delivers a well-tempered approximation to a known function that closely mimics the true potential-energy surface. As is to be expected, since there is only roundoff error present in the LSTH input data, even more significant figures of fitting accuracy are obtained. The RMS error of the DAF fit, of the LSTH surface at the input points, is 0.0274 kcal/mol, and a smooth fit, accurate to better than 1cm -1 , can be obtained using more than 287 input data points. copyright 1997 American Institute of Physics

  3. BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment

    Science.gov (United States)

    Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

    2014-01-01

    BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

  4. [Potential distribution and geographic characteristics of wild populations of Vanilla planifolia (Orchidaceae) Oaxaca, Mexico].

    Science.gov (United States)

    Hernandez-Ruiz, Jesús; Herrera-Cabrera, B Edgar; Delgado-Alvarado, Adriana; Salazar-Rojas, Víctor M; Bustamante-Gonzalez, Ángel; Campos-Contreras, Jorge E; Ramírez-Juarez, Javier

    2016-03-01

    Wild specimens of Vanilla planifolia represent a vital part of this resource primary gene pool, and some plants have only been reported in Oaxaca, Mexico. For this reason, we studied its geographical distribution within the state, to locate and describe the ecological characteristics of the areas where they have been found, in order to identify potential areas of establishment. The method comprised four stages: 1) the creation of a database with herbarium records, 2) the construction of the potential distribution based on historical herbarium records for the species, using the model of maximum entropy (MaxEnt) and 22 bioclimatic variables as predictors; 3) an in situ systematic search of individuals, based on herbarium records and areas of potential distribution in 24 municipalities, to determine the habitat current situation and distribution; 4) the description of the environmental factors of potential ecological niches generated by MaxEnt. A review of herbarium collections revealed a total of 18 records of V. planifolia between 1939 and 1998. The systematic search located 28 plants distributed in 12 sites in 95 364 Km(2). The most important variables that determined the model of vanilla potential distribution were: precipitation in the rainy season (61.9 %), soil moisture regime (23.4 %) and precipitation during the four months of highest rainfall (8.1 %). The species potential habitat was found to be distributed in four zones: wet tropics of the Gulf of Mexico, humid temperate, humid tropical, and humid temperate in the Pacific. Precipitation oscillated within the annual ranges of 2 500 to 4 000 mm, with summer rains, and winter precipitation as 5 to 10 % of the total. The moisture regime and predominating climate were udic type I (330 to 365 days of moisture) and hot humid (Am/A(C) m). The plants were located at altitudes of 200 to 1 190 masl, on rough hillsides that generally make up the foothills of mountain systems, with altitudes of 1 300 to 2 500 masl. In

  5. Momentum distribution, vibrational dynamics, and the potential of mean force in ice

    Science.gov (United States)

    Lin, Lin; Morrone, Joseph A.; Car, Roberto; Parrinello, Michele

    2011-06-01

    By analyzing the momentum distribution obtained from path integral and phonon calculations we find that the protons in hexagonal ice experience an anisotropic quasiharmonic effective potential with three distinct principal frequencies that reflect molecular orientation. Due to the importance of anisotropy, anharmonic features of the environment cannot be extracted from existing experimental distributions that involve the spherical average. The full directional distribution is required, and we give a theoretical prediction for this quantity that could be verified in future experiments. Within the quasiharmonic context, anharmonicity in the ground-state dynamics of the proton is substantial and has quantal origin, a finding that impacts the interpretation of several spectroscopies.

  6. Effect of remote sea surface temperature change on tropical cyclone potential intensity.

    Science.gov (United States)

    Vecchi, Gabriel A; Soden, Brian J

    2007-12-13

    The response of tropical cyclone activity to global warming is widely debated. It is often assumed that warmer sea surface temperatures provide a more favourable environment for the development and intensification of tropical cyclones, but cyclone genesis and intensity are also affected by the vertical thermodynamic properties of the atmosphere. Here we use climate models and observational reconstructions to explore the relationship between changes in sea surface temperature and tropical cyclone 'potential intensity'--a measure that provides an upper bound on cyclone intensity and can also reflect the likelihood of cyclone development. We find that changes in local sea surface temperature are inadequate for characterizing even the sign of changes in potential intensity, but that long-term changes in potential intensity are closely related to the regional structure of warming; regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. We use this relationship to reconstruct changes in potential intensity over the twentieth century from observational reconstructions of sea surface temperature. We find that, even though tropical Atlantic sea surface temperatures are currently at a historical high, Atlantic potential intensity probably peaked in the 1930s and 1950s, and recent values are near the historical average. Our results indicate that--per unit local sea surface temperature change--the response of tropical cyclone activity to natural climate variations, which tend to involve localized changes in sea surface temperature, may be larger than the response to the more uniform patterns of greenhouse-gas-induced warming.

  7. Hot-electron-mediated desorption rates calculated from excited-state potential energy surfaces

    DEFF Research Database (Denmark)

    Olsen, Thomas; Gavnholt, Jeppe; Schiøtz, Jakob

    2009-01-01

    We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various...... transition-metal surfaces and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system with parameters obtained from the excited-state potential energy surface and show that this model can describe desorption dynamics...... in both the DIET and DIMET regimes and reproduce the power-law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong....

  8. Surface potential effects in low-energy current image diffraction patterns observed on the Al(001) surface

    International Nuclear Information System (INIS)

    Fine structure observed in high-resolution low-energy electron diffraction (LEED) measurements near the energy threshold for emergence of new beams has been attributed to surface barrier effects. Recently, the surface barrier has been suggested as the source of the fine structure observed in current image diffraction (CID) patterns obtained by rastering the primary beam across an Al(001) crystal surface at a constant energy. This suggestion was based on kinematic arguments which correlated the emergence angle for a new electron beam with the observed structure in the CID pattern. In this work, the angular dependence of the elastic component of the total crystal reflectivity is calculated at constant energy. The calculations are based on full dynamical theories such as used in LEED but incorporating different surface barrier models to account for the saturating image potential. The results are compared with the experimental CID results

  9. Effect of surface tension on the behavior of adhesive contact based on Lennard-Jones potential law

    Science.gov (United States)

    Zhu, Xinyao; Xu, Wei

    2018-02-01

    The present study explores the effect of surface tension on adhesive contact behavior where the adhesion is interpreted by long-range intermolecular forces. The adhesive contact is analyzed using the equivalent system of a rigid sphere and an elastic half space covered by a membrane with surface tension. The long-range intermolecular forces are modeled with the Lennard‒Jones (L‒J) potential law. The current adhesive contact issue can be represented by a nonlinear integral equation, which can be solved by Newton‒Raphson method. In contrast to previous studies which consider intermolecular forces as short-range, the present study reveals more details of the features of adhesive contact with surface tension, in terms of jump instabilities, pull-off forces, pressure distribution within the contact area, etc. The transition of the pull-off force is not only consistent with previous studies, but also presents some new interesting characteristics in the current situation.

  10. Mixed Potential Energy Surfaces of the Ultrafast Isomerization of Retinal in Bacteriorhodopsin

    OpenAIRE

    Prokhorenko Valentyn I.; Morizumi Takefumi; Halpin Alexei; Johnson Philip J. M.; Ernst Oliver P.; Dwayne Miller R. J.

    2013-01-01

    We observe, using electronic two-dimensional photon echo spectroscopy, that the cis and trans potential energy surfaces of the ultrafast isomerization of retinal in bacteriorhodopsin are mixed via the hydrogen out of plane (HOOP) mode.

  11. Mixed Potential Energy Surfaces of the Ultrafast Isomerization of Retinal in Bacteriorhodopsin

    Directory of Open Access Journals (Sweden)

    Prokhorenko Valentyn I.

    2013-03-01

    Full Text Available We observe, using electronic two-dimensional photon echo spectroscopy, that the cis and trans potential energy surfaces of the ultrafast isomerization of retinal in bacteriorhodopsin are mixed via the hydrogen out of plane (HOOP mode.

  12. Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces

    DEFF Research Database (Denmark)

    Hall, B.; Deumens, E.; Ohrn, Y.

    2014-01-01

    A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...

  13. On the relation of 6.7-micron water vapour features to isentropic distributions of potential vorticity

    Science.gov (United States)

    Manney, Gloria L.; Stanford, John L.

    1987-01-01

    Currently available isentropic maps of potential vorticity (IPV maps) are of low resolution. In this note, the possibility of using 6.7-micron satellite-derived water vapor measurements to obtain higher resolution information about IPV distributions is examined. While attempts to related the two data sets analytically have so far proved unsuccessful, a qualitative comparison shows very similar features in both. The results obtained here suggest that, over limited areas, it may be possible to use 6.7-micron brightness temperatures to obtain approximate contours for water vapor mixing ratio on a particular isentropic surface in the upper troposphere. For areas free of high clouds, these contours are expected to parallel the IPV contours on this surface. In a case study, the resulting map exhibits dramatically increased horizontal resolution compared with present IPV maps, detailing an intriguing upper-tropospheric feature at subsynoptic scales.

  14. First Principle Calculation of Electronic, Optical Properties and Photocatalytic Potential of CuO Surfaces

    OpenAIRE

    Ahmad, Faozan

    2016-01-01

    We have performed DFT calculations of electronic structure, optical properties and photocatalytic potential of the low-index surfaces of CuO. Photocatalytic reaction on the surface of semiconductor requires the appropriate band edge of the semiconductor surface to drive redox reactions. The calculation begins with the electronic structure of bulk system; it aims to determine realistic input parameters and band gap prediction. CuO is an antiferromagnetic material with strong electronic correla...

  15. Geographic conditions for distribution of agriculture and potentials for tourism development on Mokra mountain

    OpenAIRE

    Knežević Marko; Knežević Danilo

    2009-01-01

    This work considers important natural conditions of distribution of agricultural production, cattle breeding in particular, and also potentials for tourism development on Mokra mountain. Half-nomadic cattle breeding in mountain settlements was highly developed in recent past. It represented the main source of existence for local highlanders. Today it is neglected and in phase of dying out. The mountain disposes with excellent natural potentials for ecological and mountain tourism, but these p...

  16. Ion-step method for surface potential sensing of silicon nanowires

    NARCIS (Netherlands)

    Chen, S.; van Nieuwkasteele, Jan William; van den Berg, Albert; Eijkel, Jan C.T.

    2016-01-01

    This paper presents a novel stimulus-response method for surface potential sensing of silicon nanowire (Si NW) field-effect transistors. When an "ion-step" from low to high ionic strength is given as a stimulus to the gate oxide surface, an increase of double layer capacitance is therefore expected.

  17. The sand extraction potential of embedded land surface lowering in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Kleine, M.P.E. de; Veldkamp, J.G.; Dubelaar, C.W.; Pietersen, H.S.

    2004-01-01

    In the Netherlands, mineral extraction by means of dredging or quarrying meets with considerable societal resistance. Land surface lowering prior to large land reconstruction projects may raise fewer objections. We have calculated the potential yields of sand and gravel from land surface lowering

  18. The sand extraction potential of embedded land surface lowering in the Netherlands

    NARCIS (Netherlands)

    Van der Meulen, M.J.; De Kleine, M.P.E.; Veldkamp, J.G.; Dubbelaar, C.W.; Pietersen, H.S.

    2004-01-01

    In the Netherlands, mineral extraction by means of dredging or quarrying meets with considerable societal resistance. Land surface lowering prior to large land reconstruction projects may raise fewer objections. We have calculated the potential yields of sand and gravel form land surface lowering

  19. Characterization of the surface of protein-adsorbed dental materials by wetting and streaming potential measurements

    NARCIS (Netherlands)

    Matsumura, H.; Kawasaki, K.; Okumura, N.; Kambara, M.; Norde, W.

    2003-01-01

    In this study we have elucidated the water-wettability and the electrokinetic surface potential of protein-covered dental materials. The proteins used here as typical proteins were human serum albumin and lysozyme from hen*s egg. The wettability (hydrophobicity/hydrophilicity) and the surface

  20. Characterization of the surface of protein-adsorbed dental materials by wetting and streaming potential measurements

    NARCIS (Netherlands)

    Matsumura, H; Kawasaki, K; Okumura, N; Kambara, M; Norde, W

    2003-01-01

    In this study we have elucidated the water-wettability and the electrokinetic surface potential of protein-covered dental materials. The proteins used here as typical proteins were human serum albumin and lysozyme from hen's egg. The wettability (hydrophobicity/hydrophilicity) and the surface

  1. Hydrophobicity, surface tension, and zeta potential measurements of glass-reinforced hydroxyapatite composites.

    Science.gov (United States)

    Lopes, M A; Monteiro, F J; Santos, J D; Serro, A P; Saramago, B

    1999-06-15

    Wettability and zeta potential studies were performed to characterize the hydrophobicity, surface tension, and surface charge of P2O5-glass-reinforced hydroxyapatite composites. Quantitative phase analysis was performed by the Rietveld method using GSAS software applied to X-ray diffractograms. Surface charge was assessed by zeta potential measurements. Protein adsorption studies were performed using vitronectin. Contact angles and surface tensions variation with time were determined by the sessile and pendent drop techniques, respectively, using ADSA-P software. The highest (-18.1 mV) and lowest (-28.7 mV) values of zeta potential were found for hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP), respectively, with composite materials presenting values in between. All studied bioceramic materials showed similar solid surface tension. For HA and beta-TCP, solid surface tensions of 46.7 and 45.3 mJ/m2, respectively, were obtained, while composites presented intermediate surface tension values. The dispersive component of surface tension was the predominant one for all materials studied. Adhesion work values between the vitronectin solution and HA and beta-TCP were found to be 79.8 and 88.0 mJ/m2, respectively, while the 4.0 wt % glass composites showed slightly lower values than the 2.5 wt % ones. The presence of beta-TCP influenced surface charge, hydrophobicity, and protein adsorption of the glass-reinforced HA composites, and therefore indirectly affected cell-biomaterial interactions.

  2. Effect of an end plate on surface pressure distributions of two swept wings

    Directory of Open Access Journals (Sweden)

    Mohammad Reza SOLTANI

    2017-10-01

    Full Text Available A series of wind tunnel tests was conducted to examine how an end plate affects the pressure distributions of two wings with leading edge (LE sweep angles of 23° and 40°. All the experiments were carried out at a midchord Reynolds number of 8×105, covering an angle of attack (AOA range from −2° to 14°. Static pressure distribution measurements were acquired over the upper surfaces of the wings along three chordwise rows and one spanwise direction at the wing quarter-chord line. The results of the tests confirm that at a particular AOA, increasing the sweep angle causes a noticeable decrease in the upper-surface suction pressure. Furthermore, as the sweep angle increases, the development of a laminar separation bubble near the LEs of the wings takes place at higher AOAs. On the other hand, spanwise pressure measurements show that increasing the wing sweep angle results in forming a stronger vortex on the quarter-chord line which has lower sensitivity to AOA variation and remains substantially attached to the wing surface for higher AOAs than that can be achieved in the case of a lower sweep angle. In addition, data obtained indicate that installing an end plate further reinforces the spanwise flow over the wing surface, thus affecting the pressure distribution.

  3. Distribution of 137Cs in surface seawater and sediment around Sabahs Sulu-Sulawesi Sea

    International Nuclear Information System (INIS)

    Mohd Izwan Abdul Aziz; Ahmad Sanadi Abu Bakar; Yii, Mei Wo; Nurrul Assyikeen Jaffary; Zaharudin Ahmad

    2010-01-01

    The studies on distribution of 137 Cs in surface seawater and sediment around Sabahs Sulu-Sulawesi Sea were carried out during Ekspedisi Pelayaran Saintifik Perdana (EPSP) in July 2009. About sixteen and twenty five sampling locations were identified for surface seawater and sediment respectively in Sabahs Sulu-Sulawesi Sea. Large volumes of seawater samples are collected and co-precipitation technique was employed to concentrate cesium content before known amounts of 134 Cs tracer were added as yield determinant. Grab sampler were used to collect surface sediment sample. The caesium precipitate and sediment were dried and finely ground before counted using gamma-ray spectrometry system at 661 keV. The activity of 137 Cs was found in surface seawater and sediment to be in the range 1.73 Bq/ m 3 to 5.50 Bq/ m 3 and 1.15 Bq/ kg to 4.53 Bq/ kg respectively. (author)

  4. Influences of climate change on the potential distribution of Lutzomyia longipalpis sensu lato (Psychodidae: Phlebotominae).

    Science.gov (United States)

    Peterson, A Townsend; Campbell, Lindsay P; Moo-Llanes, David A; Travi, Bruno; González, Camila; Ferro, María Cristina; Ferreira, Gabriel Eduardo Melim; Brandão-Filho, Sinval P; Cupolillo, Elisa; Ramsey, Janine; Leffer, Andreia Mauruto Chernaki; Pech-May, Angélica; Shaw, Jeffrey J

    2017-09-01

    This study explores the present day distribution of Lutzomyia longipalpis in relation to climate, and transfers the knowledge gained to likely future climatic conditions to predict changes in the species' potential distribution. We used ecological niche models calibrated based on occurrences of the species complex from across its known geographic range. Anticipated distributional changes varied by region, from stability to expansion or decline. Overall, models indicated no significant north-south expansion beyond present boundaries. However, some areas suitable both at present and in the future (e.g., Pacific coast of Ecuador and Peru) may offer opportunities for distributional expansion. Our models anticipated potential range expansion in southern Brazil and Argentina, but were variably successful in anticipating specific cases. The most significant climate-related change anticipated in the species' range was with regard to range continuity in the Amazon Basin, which is likely to increase in coming decades. Rather than making detailed forecasts of actual locations where Lu. longipalpis will appear in coming years, our models make interesting and potentially important predictions of broader-scale distributional tendencies that can inform heath policy and mitigation efforts. Copyright © 2017 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

  5. Organic-walled dinoflagellate cysts in western equatorial Atlantic surface sediments: distributions and their relation to environment.

    Science.gov (United States)

    Vink; Zonneveld; Willems

    2000-11-01

    In contrast to the wide range of studies carried out in temperate and high-latitude oceanic regions, only a few studies have focused on recent and Holocene organic-walled dinoflagellate cyst assemblages from the tropics. This information is, however, essential for fully understanding the ability of species to adapt to different oceanographic regimes, and ultimately their potential application to local and regional palaeoenvironmental and palaeoceanographic reconstructions. Surface sediment samples of the western equatorial Atlantic Ocean north of Brazil, an area greatly influenced by Amazon River discharge waters, were therefore analysed in detail for their organic-walled dinoflagellate cyst content. A diverse association of 43 taxa was identified, and large differences in cyst distribution were observed. The cyst thanatocoenosis in bottom sediments reflects the seasonal advection of Amazon River discharge water through the Guyana Current and the North Equatorial Countercurrent well into the North Atlantic. To establish potential links between cyst distribution and the environmental conditions of the upper water column, distribution patterns were compared with mean temperature, salinity, density and stratification gradients within the upper water column (0-100m) over different times of the year, using correspondence analysis and canonical correspondence analysis. The analyses show that differences in these parameters only play a subordinate role in determining species distribution. Instead, nutrient availability, or related factors, dominates the distribution pattern. The only possible indicators of slightly reduced salinities are Trinovantedinium applanatum and Lingulodinium machaerophorum. Four assemblage groups of cyst taxa with similar environmental affinities related to specific water masses/currents can be distinguished and have potential for palaeoenvironmental reconstruction.

  6. Streaming potential revisited: the influence of convection on the surface conductivity.

    Science.gov (United States)

    Saini, Rakesh; Garg, Abhinandan; Barz, Dominik P J

    2014-09-16

    Electrokinetic phenomena play an important role in the electrical characterization of surfaces. In terms of planar or porous substrates, streaming potential and/or streaming current measurements can be used to determine the zeta potential of the substrates in contact with aqueous electrolytes. In this work, we perform electrical impedance spectroscopy measurements to infer the electrical resistance in a microchannel with the same conditions as for a streaming potential experiment. Novel correlations are derived to relate the streaming current and streaming potential to the Reynolds number of the channel flow. Our results not only quantify the influence of surface conductivity, and here especially the contribution of the stagnant layer, but also reveal that channel resistance and therefore zeta potential are influenced by the flow in the case of low ionic strengths. We conclude that convection can have a significant impact on the electrical double layer configuration which is reflected by changes in the surfaces conductivity.

  7. An atlas of monthly mean distributions of SSMI surface wind speed, ARGOS buoy drift, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1991

    Science.gov (United States)

    Halpern, D.; Knauss, W.; Brown, O.; Wentz, F.

    1993-01-01

    The following monthly mean global distributions for 1991 are presented with a common color scale and geographical map: 10-m height wind speed estimated from the Special Sensor Microwave Imager (SSMI) on a United States Air Force Defense Meteorological Satellite Program (DMSP) spacecraft; sea surface temperature estimated from the advanced very high resolution radiometer (AVHRR/2) on a U.S. National Oceanic and Atmospheric Administration (NOAA) spacecraft; Cartesian components of free-drifting buoys which are tracked by the ARGOS navigation system on NOAA satellites; and Cartesian components of the 10-m height wind vector computed by the European Center for Medium-Range Weather Forecasting (ECMWF). Charts of monthly mean value, sampling distribution, and standard deviation value are displayed. Annual mean distributions are displayed.

  8. An atlas of monthly mean distributions of SSMI surface wind speed, ARGOS buoy drift, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1990

    Science.gov (United States)

    Halpern, D.; Knauss, W.; Brown, O.; Wentz, F.

    1993-01-01

    The following monthly mean global distributions for 1990 are proposed with a common color scale and geographical map: 10-m height wind speed estimated from the Special Sensor Microwave Imager (SSMI) on a United States (US) Air Force Defense Meteorological Satellite Program (DMSP) spacecraft; sea surface temperature estimated from the advanced very high resolution radiometer (AVHRR/2) on a U.S. National Oceanic and Atmospheric Administration (NOAA) spacecraft; Cartesian components of free drifting buoys which are tracked by the ARGOS navigation system on NOAA satellites; and Cartesian components on the 10-m height wind vector computed by the European Center for Medium-Range Weather Forecasting (ECMWF). Charts of monthly mean value, sampling distribution, and standard deviation values are displayed. Annual mean distributions are displayed.

  9. Surface Complexation Modeling of Calcite Zeta Potential Measurement in Mixed Brines for Carbonate Wettability Characterization

    Science.gov (United States)

    Song, J.; Zeng, Y.; Biswal, S. L.; Hirasaki, G. J.

    2017-12-01

    We presents zeta potential measurements and surface complexation modeling (SCM) of synthetic calcite in various conditions. The systematic zeta potential measurement and the proposed SCM provide insight into the role of four potential determining cations (Mg2+, SO42- , Ca2+ and CO32-) and CO2 partial pressure in calcite surface charge formation and facilitate the revealing of calcite wettability alteration induced by brines with designed ionic composition ("smart water"). Brines with varying potential determining ions (PDI) concentration in two different CO2 partial pressure (PCO2) are investigated in experiments. Then, a double layer SCM is developed to model the zeta potential measurements. Moreover, we propose a definition for contribution of charged surface species and quantitatively analyze the variation of charged species contribution when changing brine composition. After showing our model can accurately predict calcite zeta potential in brines containing mixed PDIs, we apply it to predict zeta potential in ultra-low and pressurized CO2 environments for potential applications in carbonate enhanced oil recovery including miscible CO2 flooding and CO2 sequestration in carbonate reservoirs. Model prediction reveals that pure calcite surface will be positively charged in all investigated brines in pressurized CO2 environment (>1atm). Moreover, the sensitivity of calcite zeta potential to CO2 partial pressure in the various brine is found to be in the sequence of Na2CO3 > Na2SO4 > NaCl > MgCl2 > CaCl2 (Ionic strength=0.1M).

  10. Surface flux density distribution characteristics of bulk high-T c superconductor in external magnetic field

    International Nuclear Information System (INIS)

    Nishikawa, H.; Torii, S.; Yuasa, K.

    2005-01-01

    This paper describes the measured results of the two-dimensional flux density distribution of a YBCO bulk under applied AC magnetic fields with various frequency. Melt-processed oxide superconductors have been developed in order to obtain strong pinning forces. Various electric mechanical systems or magnetic levitation systems use those superconductors. The major problem is that cracks occur because the bulk superconductors are brittle. The bulk may break in magnetizing process after cracks make superconducting state instable. The trapped flux density and the permanent current characteristics of bulk superconductors have been analyzed, so as to examine the magnetizing processes or superconducting states of the bulk. In those studies, the two-dimensional surface flux density distributions of the bulk in static fields are discussed. On the other hand, the distributions in dynamic fields are little discussed. We attempted to examine the states of the bulk in the dynamic fields, and made a unique experimental device which has movable sensors synchronized with AC applied fields. As a result, the two-dimensional distributions in the dynamic fields are acquired by recombining the one-dimensional distributions. The dynamic states of the flux of the bulk and the influences of directions of cracks are observed from the distributions. In addition, a new method for measuring two-dimensional flux density distribution under dynamic magnetic fields is suggested

  11. Shifts in the potential distribution of Sky Island plant communities in response to climate change

    Science.gov (United States)

    John A. Kupfer; Jeff Balmat; Jacqueline L. Smith

    2005-01-01

    To examine potential responses of sky island ecosystem pattern to projected climate changes, we used topographic and climatic data to develop a predictive model of plant community distribution in Saguaro National Park East, AZ. Increasing temperatures led to an upslope movement of communities and increased the area of desert scrub at the expense of montane conifer...

  12. Intrinsic potential of cell membranes: opposite effects of lipid transmembrane asymmetry and asymmetric salt ion distribution

    DEFF Research Database (Denmark)

    Gurtovenko, Andrey A; Vattulainen, Ilpo

    2009-01-01

    Using atomic-scale molecular dynamics simulations, we consider the intrinsic cell membrane potential that is found to originate from a subtle interplay between lipid transmembrane asymmetry and the asymmetric distribution of monovalent salt ions on the two sides of the cell membrane. It turns out...

  13. Full-dimensional diabatic potential energy surfaces including dissociation: the ²E″ state of NO₃.

    Science.gov (United States)

    Eisfeld, Wolfgang; Vieuxmaire, Olivier; Viel, Alexandra

    2014-06-14

    A scheme to produce accurate full-dimensional coupled diabatic potential energy surfaces including dissociative regions and suitable for dynamical calculations is proposed. The scheme is successfully applied to model the two-sheeted surface of the (2)E″ state of the NO3 radical. An accurate potential energy surface for the NO₃⁻ anion ground state is developed as well. Both surfaces are based on high-level ab initio calculations. The model consists of a diabatic potential matrix, which is expanded to higher order in terms of symmetry polynomials of symmetry coordinates. The choice of coordinates is key for the accuracy of the obtained potential energy surfaces and is discussed in detail. A second central aspect is the generation of reference data to fit the expansion coefficients of the model for which a stochastic approach is proposed. A third ingredient is a new and simple scheme to handle problematic regions of the potential energy surfaces, resulting from the massive undersampling by the reference data unavoidable for high-dimensional problems. The final analytical diabatic surfaces are used to compute the lowest vibrational levels of NO₃⁻ and the photo-electron detachment spectrum of NO₃⁻ leading to the neutral radical in the (2)E″ state by full dimensional multi-surface wave-packet propagation for NO3 performed using the Multi-Configuration Time Dependent Hartree method. The achieved agreement of the simulations with available experimental data demonstrates the power of the proposed scheme and the high quality of the obtained potential energy surfaces.

  14. Distribution, enrichment and sources of thallium in the surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea.

    Science.gov (United States)

    Zhuang, Wen; Gao, Xuelu

    2015-07-15

    The concentrations of thallium (Tl) in the surface sediments of the southwestern coastal Laizhou Bay and the rivers it connects were determined. In riverine sediments, the Tl concentrations ranged from 0.34 to 0.76 μg g(-1) in summer; in autumn, the corresponding data were 0.35-1.08 μg g(-1). In marine sediments, the Tl concentrations ranged from 0.36 to 0.58 μg g(-1) in summer; and from 0.30 to 0.56 μg g(-1) in autumn. The grain size, Al and Fe oxides were major factors affecting Tl distribution. Tl in the surface sediments of the studied area was mainly from the natural input with the non-natural input as a subsidiary source. The low concentrations of Tl made it hard to cause potential negative environmental effects in this area. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from the Bering Sea and western Arctic Ocean.

    Science.gov (United States)

    Zhao, Mengwei; Wang, Weiguo; Liu, Yanguang; Dong, Linsen; Jiao, Liping; Hu, Limin; Fan, Dejiang

    2016-03-15

    To analyze the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and evaluate their potential ecological risks, the concentrations of 16 PAHs were measured in 43 surface sediment samples from the Bering Sea and western Arctic Ocean. Total PAH (tPAH) concentrations ranged from 36.95 to 150.21 ng/g (dry weight). In descending order, the surface sediment tPAH concentrations were as follows: Canada Basin>northern Chukchi Sea>Chukchi Basin>southern Chukchi Sea>Aleutian Basin>Makarov Basin>Bering Sea shelf. The Bering Sea and western Arctic Ocean mainly received PAHs of pyrogenic origin due to pollution caused by the incomplete combustion of fossil fuels. The concentrations of PAHs in the sediments of the study areas did not exceed effects range low (ERL) values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Adsorption of urinary components influences the zeta potential of uropathogen surfaces

    NARCIS (Netherlands)

    Habash, MB; van der Mei, HC; Busscher, HJ; Reid, G

    2000-01-01

    Zeta potential distributions of five uropathogens were measured in urines collected after increased water intake, consumption of cranberry supplements, or intake of ascorbic acid by volunteers. Zeta potentials of bacteria in urine from ascorbic acid consumption shifted towards less negative values

  17. The Variation of Planetary Surfaces' Structure and Size Distribution with Depth

    Science.gov (United States)

    Charalambous, C. A.; Pike, W. T.

    2014-12-01

    The particle, rock and boulder size distribution of a planetary surface bring important implications not only to crucial aspects of future missions but also to the better understanding of planetary and earth sciences. By exploiting a novel statistical model, the evolution of particle fragmentation phenomena can be understood in terms of a descriptive maturity index, a measure of the number of fragmentation events that have produced the soil. This statistical model, which is mathematically constructed via fundamental physical principles, has been validated by terrestrial mineral grinding data and impact experiments. Applying the model to planetary surfaces, the number of fragmentation events is determined by production function curves that quantify the degree of impact cratering. The model quantifies the variation of the maturity index of the regolith with depth, with a high maturity index at the surface decreasing to a low index corresponding to the megaregolith of a blocky population and fractured bedrock. The measured lunar and martian particle size distributions at the surface is well matched by the model over several orders of magnitude. The continuous transition invoked by the model can be furthermore synthesised to provide temporal and spatial visualisations of the internal architecture of the Martian and Lunar regolith. Finally, the model is applied to the risk assessment and success criteria of future mission landings as well as drilling on planetary surfaces. The solutions to a variety of planetary fragmentation related problems can be found via exact mathematical foundations or through simulations using the particle population provided by the model's maturation.

  18. Anticancer drugs in Portuguese surface waters - Estimation of concentrations and identification of potentially priority drugs.

    Science.gov (United States)

    Santos, Mónica S F; Franquet-Griell, Helena; Lacorte, Silvia; Madeira, Luis M; Alves, Arminda

    2017-10-01

    Anticancer drugs, used in chemotherapy, have emerged as new water contaminants due to their increasing consumption trends and poor elimination efficiency in conventional water treatment processes. As a result, anticancer drugs have been reported in surface and even drinking waters, posing the environment and human health at risk. However, the occurrence and distribution of anticancer drugs depend on the area studied and the hydrological dynamics, which determine the risk towards the environment. The main objective of the present study was to evaluate the risk of anticancer drugs in Portugal. This work includes an extensive analysis of the consumption trends of 171 anticancer drugs, sold or dispensed in Portugal between 2007 and 2015. The consumption data was processed aiming at the estimation of predicted environmental loads of anticancer drugs and 11 compounds were identified as potentially priority drugs based on an exposure-based approach (PEC b > 10 ng L -1 and/or PEC c > 1 ng L -1 ). In a national perspective, mycophenolic acid and mycophenolate mofetil are suspected to pose high risk to aquatic biota. Moderate and low risk was also associated to cyclophosphamide and bicalutamide exposition, respectively. Although no evidences of risk exist yet for the other anticancer drugs, concerns may be associated with long term effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Surface Functionalization of Iron Oxide Nanoparticles with Gallic Acid as Potential Antioxidant and Antimicrobial Agents

    Directory of Open Access Journals (Sweden)

    Syed Tawab Shah

    2017-10-01

    Full Text Available In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8 nm for in situ synthesis of gallic acid functionalized magnetite IONP@GA1 and IONP@GA2, respectively, which are ultra-small particles as compared to unfunctionalized magnetite (IONP and post functionalized magnetite IONP@GA3 with average size of 10 and 11 nm respectively. All the IONPs@GA samples were found hydrophilic with stable aggregation state. Prior to commencement of experimental lab work, PASS software was used to predict the biological activities of GA and it is found that experimental antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH assay and antimicrobial studies using well diffusion method are in good agreement with the simulated results. Furthermore, the half maximal inhibitory concentration (IC50 values of DPPH antioxidant assay revealed a 2–4 fold decrease as compared to unfunctionalized IONP. In addition to antioxidant activity, all the three IONP@GA proved outstanding antimicrobial activity while testing on different bacterial and fungal strains. The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries.

  20. Surface Functionalization of Iron Oxide Nanoparticles with Gallic Acid as Potential Antioxidant and Antimicrobial Agents

    Science.gov (United States)

    Shah, Syed Tawab; Saad, Omar; Simarani, Khanom; Chowdhury, Zaira Zaman; Alhadi, Abeer A.; Al-Ani, Lina A.

    2017-01-01

    In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA) as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8 nm for in situ synthesis of gallic acid functionalized magnetite IONP@GA1 and IONP@GA2, respectively, which are ultra-small particles as compared to unfunctionalized magnetite (IONP) and post functionalized magnetite IONP@GA3 with average size of 10 and 11 nm respectively. All the IONPs@GA samples were found hydrophilic with stable aggregation state. Prior to commencement of experimental lab work, PASS software was used to predict the biological activities of GA and it is found that experimental antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and antimicrobial studies using well diffusion method are in good agreement with the simulated results. Furthermore, the half maximal inhibitory concentration (IC50) values of DPPH antioxidant assay revealed a 2–4 fold decrease as compared to unfunctionalized IONP. In addition to antioxidant activity, all the three IONP@GA proved outstanding antimicrobial activity while testing on different bacterial and fungal strains. The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries. PMID:28981476

  1. Impact of climate change on potential distribution of Chinese caterpillar fungus (Ophiocordyceps sinensis) in Nepal Himalaya.

    Science.gov (United States)

    Shrestha, Uttam Babu; Bawa, Kamaljit S

    2014-01-01

    Climate change has already impacted ecosystems and species and substantial impacts of climate change in the future are expected. Species distribution modeling is widely used to map the current potential distribution of species as well as to model the impact of future climate change on distribution of species. Mapping current distribution is useful for conservation planning and understanding the change in distribution impacted by climate change is important for mitigation of future biodiversity losses. However, the current distribution of Chinese caterpillar fungus, a flagship species of the Himalaya with very high economic value, is unknown. Nor do we know the potential changes in suitable habitat of Chinese caterpillar fungus caused by future climate change. We used MaxEnt modeling to predict current distribution and changes in the future distributions of Chinese caterpillar fungus in three future climate change trajectories based on representative concentration pathways (RCPs: RCP 2.6, RCP 4.5, and RCP 6.0) in three different time periods (2030, 2050, and 2070) using species occurrence points, bioclimatic variables, and altitude. About 6.02% (8,989 km2) area of the Nepal Himalaya is suitable for Chinese caterpillar fungus habitat. Our model showed that across all future climate change trajectories over three different time periods, the area of predicted suitable habitat of Chinese caterpillar fungus would expand, with 0.11-4.87% expansion over current suitable habitat. Depending upon the representative concentration pathways, we observed both increase and decrease in average elevation of the suitable habitat range of the species.

  2. Climate change and the potential global distribution of Aedes aegypti: spatial modelling using GIS and CLIMEX.

    Science.gov (United States)

    Khormi, Hassan M; Kumar, Lalit

    2014-05-01

    We examined the potential added risk posed by global climate change on the dengue vector Aedes aegypti abundance using CLIMEX, a powerful tool for exploring the relationship between the fundamental and realised niche of any species. After calibrating the model using data from several knowledge domains, including geographical distribution records, we estimated potential distributions of the mosquito under current and future potential scenarios. The impact of climate change on its potential distribution was assessed with two global climate models, the CSIRO-Mk3.0 and the MIROC-H, run with two potential, future emission scenarios (A1B and A2) published by the Intergovernmental Panel on Climate Change. We compared today's climate situation with two arbitrarily chosen future time points (2030 and 2070) to see the impact on the worldwide distribution of A. aegypti . The model for the current global climate indicated favourable areas for the mosquito within its known distribution in tropical and subtropical areas. However, even if much of the tropics and subtropics will continue to be suitable, the climatically favourable areas for A. aegypti globally are projected to contract under the future scenarios produced by these models, while currently unfavourable areas, such as inland Australia, the Arabian Peninsula, southern Iran and some parts of North America may become climatically favourable for this mosquito species. The climate models for the Aedes dengue vector presented here should be useful for management purposes as they can be adapted for decision/making regarding allocation of resources for dengue risk toward areas where risk infection remains and away from areas where climatic suitability is likely to decrease in the future.

  3. Spatial Distribution and Fuzzy Health Risk Assessment of Trace Elements in Surface Water from Honghu Lake

    Directory of Open Access Journals (Sweden)

    Fei Li

    2017-09-01

    Full Text Available Previous studies revealed that Honghu Lake was polluted by trace elements due to anthropogenic activities. This study investigated the spatial distribution of trace elements in Honghu Lake, and identified the major pollutants and control areas based on the fuzzy health risk assessment at screening level. The mean total content of trace elements in surface water decreased in the order of Zn (18.04 μg/L > Pb (3.42 μg/L > Cu (3.09 μg/L > Cr (1.63 μg/L > As (0.99 μg/L > Cd (0.14 μg/L, within limits of Drinking Water Guidelines. The results of fuzzy health risk assessment indicated that there was no obvious non-carcinogenic risk to human health, while carcinogenic risk was observed in descending order of As > Cr > Cd > Pb. As was regarded to have the highest carcinogenic risk among selected trace elements because it generally accounted for 64% of integrated carcinogenic risk. Potential carcinogenic risk of trace elements in each sampling site was approximately at medium risk level (10−5 to 10−4. The areas in the south (S4, S13, and S16 and northeast (S8, S18, and S19 of Honghu Lake were regarded as the risk priority control areas. However, the corresponding maximum memberships of integrated carcinogenic risk in S1, S3, S10–S13, S15, and S18 were of relatively low credibility (50–60%, and may mislead the decision-makers in identifying the risk priority areas. Results of fuzzy assessment presented the subordinate grade and corresponding reliability of risk, and provided more full-scale results for decision-makers, which made up for the deficiency of certainty assessment to a certain extent.

  4. Probing surface distributions of α clusters in 20Ne via α -transfer reaction

    Science.gov (United States)

    Fukui, Tokuro; Taniguchi, Yasutaka; Suhara, Tadahiro; Kanada-En'yo, Yoshiko; Ogata, Kazuyuki

    2016-03-01

    Background: Direct evidence of the α -cluster manifestation in bound states has not been obtained yet, although a number of experimental studies were carried out to extract the information of the clustering. In particular in conventional analyses of α -transfer reactions, there exist a few significant problems on reaction models, which are insufficient to qualitatively discuss the cluster structure. Purpose: We aim to verify the manifestation of the α -cluster structure from observables. As the first application, we plan to extract the spatial information of the cluster structure of the 20Ne nucleus in its ground state through the cross section of the α -transfer reaction 16O(6Li,d )20Ne. Methods: For the analysis of the transfer reaction, we work with the coupled-channel Born approximation (CCBA) approach, in which the breakup effect of 6Li is explicitly taken into account by means of the continuum-discretized coupled-channel method based on the three-body α +d +16O model. The two methods are adopted to calculate the overlap function between 20Ne and α +16O ; one is the microscopic cluster model (MCM) with the generator coordinate method, and the other is the phenomenological two-body potential model (PM). Results: We show that the CCBA calculation with the MCM wave function gives a significant improvement of the theoretical result on the angular distribution of the transfer cross section, which is consistent with the experimental data. Employing the PM, it is discussed which region of the cluster wave function is probed on the transfer cross section. Conclusions: It is found that the surface region of the cluster wave function is sensitive to the cross section. The present work is situated as the first step in obtaining important information to systematically investigate the cluster structure.

  5. Efficient Geometry Minimization and Transition Structure Optimization Using Interpolated Potential Energy Surfaces and Iteratively Updated Hessians.

    Science.gov (United States)

    Zheng, Jingjing; Frisch, Michael J

    2017-12-12

    An efficient geometry optimization algorithm based on interpolated potential energy surfaces with iteratively updated Hessians is presented in this work. At each step of geometry optimization (including both minimization and transition structure search), an interpolated potential energy surface is properly constructed by using the previously calculated information (energies, gradients, and Hessians/updated Hessians), and Hessians of the two latest geometries are updated in an iterative manner. The optimized minimum or transition structure on the interpolated surface is used for the starting geometry of the next geometry optimization step. The cost of searching the minimum or transition structure on the interpolated surface and iteratively updating Hessians is usually negligible compared with most electronic structure single gradient calculations. These interpolated potential energy surfaces are often better representations of the true potential energy surface in a broader range than a local quadratic approximation that is usually used in most geometry optimization algorithms. Tests on a series of large and floppy molecules and transition structures both in gas phase and in solutions show that the new algorithm can significantly improve the optimization efficiency by using the iteratively updated Hessians and optimizations on interpolated surfaces.

  6. Effect of distribution of striated laser hardening tracks on dry sliding wear resistance of biomimetic surface

    Science.gov (United States)

    Su, Wei; Zhou, Ti; Zhang, Peng; Zhou, Hong; Li, Hui

    2018-01-01

    Some biological surfaces were proved to have excellent anti-wear performance. Being inspired, Nd:YAG pulsed laser was used to create striated biomimetic laser hardening tracks on medium carbon steel samples. Dry sliding wear tests biomimetic samples were performed to investigate specific influence of distribution of laser hardening tracks on sliding wear resistance of biomimetic samples. After comparing wear weight loss of biomimetic samples, quenched sample and untreated sample, it can be suggested that the sample covered with dense laser tracks (3.5 mm spacing) has lower wear weight loss than the one covered with sparse laser tracks (4.5 mm spacing); samples distributed with only dense laser tracks or sparse laser tracks (even distribution) were proved to have better wear resistance than samples distributed with both dense and sparse tracks (uneven distribution). Wear mechanisms indicate that laser track and exposed substrate of biomimetic sample can be regarded as hard zone and soft zone respectively. Inconsecutive striated hard regions, on the one hand, can disperse load into small branches, on the other hand, will hinder sliding abrasives during wear. Soft regions with small range are beneficial in consuming mechanical energy and storing lubricative oxides, however, soft zone with large width (>0.5 mm) will be harmful to abrasion resistance of biomimetic sample because damages and material loss are more obvious on surface of soft phase. As for the reason why samples with even distributed bionic laser tracks have better wear resistance, it can be explained by the fact that even distributed laser hardening tracks can inhibit severe worn of local regions, thus sliding process can be more stable and wear extent can be alleviated as well.

  7. One-dimensional Schrödinger operators with singular potentials: A Schwartz distributional formulation

    Science.gov (United States)

    Dias, Nuno Costa; Jorge, Cristina; Prata, João Nuno

    2016-04-01

    Using an extension of the Hörmander product of distributions, we obtain an intrinsic formulation of one-dimensional Schrödinger operators with singular potentials. This formulation is entirely defined in terms of standard Schwartz distributions and does not require (as some previous approaches) the use of more general distributions or generalized functions. We determine, in the new formulation, the action and domain of the Schrödinger operators with arbitrary singular boundary potentials. We also consider the inverse problem, and obtain a general procedure for constructing the singular (pseudo) potential that imposes a specific set of (local) boundary conditions. This procedure is used to determine the boundary operators for the complete four-parameter family of one-dimensional Schrödinger operators with a point interaction. Finally, the δ and δ‧ potentials are studied in detail, and the corresponding Schrödinger operators are shown to coincide with the norm resolvent limit of specific sequences of Schrödinger operators with regular potentials.

  8. The PyPES library of high quality semi-global potential energy surfaces.

    Science.gov (United States)

    Sibaev, Marat; Crittenden, Deborah L

    2015-11-05

    In this article, we present a Python-based library of high quality semi-global potential energy surfaces for 50 polyatomic molecules with up to six atoms. We anticipate that these surfaces will find widespread application in the testing of new potential energy surface construction algorithms and nuclear ro-vibrational structure theories. To this end, we provide the ability to generate the energy derivatives required for Taylor series expansions to sixth order about any point on the potential energy surface in a range of common coordinate systems, including curvilinear internal, Cartesian, and normal mode coordinates. The PyPES package, along with FORTRAN, C, MATLAB and Mathematica wrappers, is available at http://sourceforge.net/projects/pypes-lib. © 2015 Wiley Periodicals, Inc.

  9. Potential impacts of climate change on the distributions and diversity patterns of European mammals

    DEFF Research Database (Denmark)

    Levinsky, Irina; Skov, Flemming; Svenning, Jens-Christian

    2007-01-01

    Abstract  The Intergovernmental Panel on Climate Change (IPCC) predicts an increase in global temperatures of between 1.4°C and 5.8°C during the 21st century, as a result of elevated CO2 levels. Using bioclimatic envelope models, we evaluate the potential impact of climate change...... (lose > 30% of their current distribution) under the two scenarios. Under the no migration assumption endemic species were predicted to be strongly negatively affected by future climatic changes, while widely distributed species would be more mildly affected. Finally, potential mammalian species...... should therefore be seen as first approximations of the potential magnitude of future climatic changes....

  10. The geographic distribution of strontium isotopes in Danish surface waters - A base for provenance studies in archaeology, hydrology and agriculture

    International Nuclear Information System (INIS)

    Frei, Karin M.; Frei, Robert

    2011-01-01

    Research highlights: → Strontium isotope data of 192 surface waters from Denmark. → Geographic baseline distribution of bio-available fractions. → Applicable for provenance studies within archaeology, geology, agriculture and hydrology. → Proposal of a band of strontium isotope values to characterize 'local' Danish signatures. - Abstract: In this paper Sr isotope signatures are reported for 192 surface water (lakes/ponds and rivers/creeks) samples from within Denmark and an isotope distribution map is presented that may serve as a base for provenance applications, including archaeological migration studies, ground water - surface water - seawater interaction/contamination monitoring, and potentially for agricultural applications, including cases of authenticity proof for particular food products. The Sr isotopic compositions of surface waters range from 87 Sr/ 86 Sr = 0.7078 to 0.7125 (average 0.7096 ± 0.0016; 2σ). This average value lies above the range of 87 Sr/ 86 Sr values between 0.7078 and 0.7082 expected from Late Cretaceous to Early Tertiary (Oligocene) limestones which form the dominant bedrock type in a NW-SE trending belt in Denmark. The elevated 87 Sr/ 86 Sr signatures >∼0.7095 are explained by additions to the surface waters of radiogenic Sr predominantly derived from the near-surface weathering and wash-out of Quarternary glaciogenic tills and soils deposited and formed during and after the last two ice age stages (Saale and Weichsel). The Sr isotopic compositions and concentrations of the surface waters can, therefore, best be modeled by a two-component mixing involving carbonaceous bedrock and glaciogenic cover sediments as the two predominant Sr sources. A feasibility study for using Sr isotopic compositions of surface waters as a proxy for bio-available Sr signatures was conducted in a representative test area on Zealand (Land of Legends, Lejre) where there is no use and application of commercial fertilizers. It is demonstrated that

  11. Plasma membrane surface potential: dual effects upon ion uptake and toxicity

    Science.gov (United States)

    Electrical properties of plasma membranes (PMs), partially controlled by the ionic composition of the bathing medium, play significant roles in the distribution of ions at the exterior surface of PMs and in the transport of ions across PMs. The effects of coexistent cations (commonly Al3+, Ca2+, Mg...

  12. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential

    Directory of Open Access Journals (Sweden)

    Maíra Maciel Mattos de Oliveira

    2010-03-01

    Full Text Available An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4 stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 ºC and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential.

  13. Spatial and energy distributions of satellite-speed helium atoms reflected from satellite-type surfaces

    International Nuclear Information System (INIS)

    Liu, S.M.; Rodgers, W.E.; Knuth, E.L.

    1977-01-01

    Interactions of satellite-speed helium atoms (accelerated in an expansion from an arc-heated supersonic-molecular-beam source) with practical satellite surfaces have been investigated experimentally. The density and energy distributions of the scattered atoms were measured using a detection system developed for this study. This detection system includes (a) a target positioning mechanism, (b) a detector rotating mechanism, and (c) a mass spectrometer and/or a retarding-field energy analyzer. (Auth.)

  14. Normal loads program for aerodynamic lifting surface theory. [evaluation of spanwise and chordwise loading distributions

    Science.gov (United States)

    Medan, R. T.; Ray, K. S.

    1974-01-01

    A description of and users manual are presented for a U.S.A. FORTRAN 4 computer program which evaluates spanwise and chordwise loading distributions, lift coefficient, pitching moment coefficient, and other stability derivatives for thin wings in linearized, steady, subsonic flow. The program is based on a kernel function method lifting surface theory and is applicable to a large class of planforms including asymmetrical ones and ones with mixed straight and curved edges.

  15. An atlas of monthly mean distributions of SSMI surface wind speed, AVHRR/2 sea surface temperature, AMI surface wind velocity, TOPEX/POSEIDON sea surface height, and ECMWF surface wind velocity during 1993

    Science.gov (United States)

    Halpern, D.; Fu, L.; Knauss, W.; Pihos, G.; Brown, O.; Freilich, M.; Wentz, F.

    1995-01-01

    The following monthly mean global distributions for 1993 are presented with a common color scale and geographical map: 10-m height wind speed estimated from the Special Sensor Microwave Imager (SSMI) on a United States (U.S.) Air Force Defense Meteorological Satellite Program (DMSP) spacecraft; sea surface temperature estimated from the Advanced Very High Resolution Radiometer (AVHRR/2) on a U.S. National Oceanic and Atmospheric Administration (NOAA) satellite; 10-m height wind speed and direction estimated from the Active Microwave Instrument (AMI) on the European Space Agency (ESA) European Remote Sensing (ERS-1) satellite; sea surface height estimated from the joint U.S.-France Topography Experiment (TOPEX)/POSEIDON spacecraft; and 10-m height wind speed and direction produced by the European Center for Medium-Range Weather Forecasting (ECMWF). Charts of annual mean, monthly mean, and sampling distributions are displayed.

  16. Estimating the transmission potential of supercritical processes based on the final size distribution of minor outbreaks.

    Science.gov (United States)

    Nishiura, Hiroshi; Yan, Ping; Sleeman, Candace K; Mode, Charles J

    2012-02-07

    Use of the final size distribution of minor outbreaks for the estimation of the reproduction numbers of supercritical epidemic processes has yet to be considered. We used a branching process model to derive the final size distribution of minor outbreaks, assuming a reproduction number above unity, and applying the method to final size data for pneumonic plague. Pneumonic plague is a rare disease with only one documented major epidemic in a spatially limited setting. Because the final size distribution of a minor outbreak needs to be normalized by the probability of extinction, we assume that the dispersion parameter (k) of the negative-binomial offspring distribution is known, and examine the sensitivity of the reproduction number to variation in dispersion. Assuming a geometric offspring distribution with k=1, the reproduction number was estimated at 1.16 (95% confidence interval: 0.97-1.38). When less dispersed with k=2, the maximum likelihood estimate of the reproduction number was 1.14. These estimates agreed with those published from transmission network analysis, indicating that the human-to-human transmission potential of the pneumonic plague is not very high. Given only minor outbreaks, transmission potential is not sufficiently assessed by directly counting the number of offspring. Since the absence of a major epidemic does not guarantee a subcritical process, the proposed method allows us to conservatively regard epidemic data from minor outbreaks as supercritical, and yield estimates of threshold values above unity. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  17. Global potential distribution of an invasive species, the yellow crazy ant (Anoplolepis gracilipes) under climate change.

    Science.gov (United States)

    Chen, Youhua

    2008-09-01

    Changes to the Earth's climate may affect the distribution of countless species. Understanding the potential distribution of known invasive species under an altered climate is vital to predicting impacts and developing management policy. The present study employs ecological niche modeling to construct the global potential distribution range of the yellow crazy ant (Anoplolepis gracilipes) using past, current and future climate scenarios. Three modeling algorithms, GARP, BioClim and Environmental Distance, were used in a comparative analysis. Output from the models suggest firstly that this insect originated from south Asia, expanded into Europe and then into Afrotropical regions, after which it formed its current distribution. Second, the invasive risk of A. gracilipes under future climatic change scenarios will become greater because of an extension of suitable environmental conditions in higher latitudes. Third, when compared to the GARP model, BioClim and Environmental Distance models were better at modeling a species' ancestral distribution. These findings are discussed in light of the predictive accuracy of these models. © 2008 ISZS, Blackwell Publishing and IOZ/CAS.

  18. Hydro power potentials of water distribution networks in public universities: A case study

    Directory of Open Access Journals (Sweden)

    Olufemi Adebola KOYA

    2017-06-01

    Full Text Available Public Universities in Southwestern Nigeria are densely populated student-resident campuses, so that provision of regular potable water and electricity are important, but power supply is not optimally available for all the necessary activities. This study assesses the hydropower potential of the water distribution networks in the Universities, with the view to augmenting the inadequate power supplies. The institutions with water distribution configuration capable of accommodating in-pipe turbine are identified; the hydropower parameters, such as the flow characteristics and the pipe geometry are determined to estimate the water power. Global positioning device is used in estimating the elevations of the distribution reservoirs and the nodal points. The hydropower potential of each location is computed incorporating Lucid® Lift-based spherical turbine in the pipeline. From the analysis, the lean and the peak water power are between 1.92 – 3.30 kW and 3.95 – 7.24 kW, respectively, for reservoir-fed distribution networks; while, a minimum of 0.72 kW is got for pipelines associated with borehole-fed overhead tanks. Possible applications of electricity generation from the water distribution networks of the public universities are recommended.

  19. Infrared spectroscopy of the Ar-C2HD complex: Potential energy surfaces

    International Nuclear Information System (INIS)

    Bemish, R.J.; Miller, R.E.

    1996-01-01

    The argon-acetylene complex has been studied by a number of experimental and theoretical groups, with the aim in mind of determining an accurate potential energy surface for this system. Both microwave and infrared spectroscopy have provided detailed rotational and vibrational constants for this system. In addition, scattering experiments have been reported and ab initio calculation performed. Even with all of this, there are still some fundamental questions that remain unanswered with regards to the shape of the potential surface. The authors will review some of this work to outline the current situation. In the present study, the authors have obtained high resolution infrared spectra of the Ar-C 2 HD complex with the aim of providing additional molecular constants that could be used to help constrain the potential. Collocation calculations are reported, using a number of potential surfaces, for this and the normal isotopomer. This additional data helps to answer some of these open questions

  20. Determination of Nerve Fiber Diameter Distribution From Compound Action Potential: A Continuous Approach.

    Science.gov (United States)

    Un, M Kerem; Kaghazchi, Hamed

    2018-01-01

    When a signal is initiated in the nerve, it is transmitted along each nerve fiber via an action potential (called single fiber action potential (SFAP)) which travels with a velocity that is related with the diameter of the fiber. The additive superposition of SFAPs constitutes the compound action potential (CAP) of the nerve. The fiber diameter distribution (FDD) in the nerve can be computed from the CAP data by solving an inverse problem. This is usually achieved by dividing the fibers into a finite number of diameter groups and solve a corresponding linear system to optimize FDD. However, number of fibers in a nerve can be measured sometimes in thousands and it is possible to assume a continuous distribution for the fiber diameters which leads to a gradient optimization problem. In this paper, we have evaluated this continuous approach to the solution of the inverse problem. We have utilized an analytical function for SFAP and an assumed a polynomial form for FDD. The inverse problem involves the optimization of polynomial coefficients to obtain the best estimate for the FDD. We have observed that an eighth order polynomial for FDD can capture both unimodal and bimodal fiber distributions present in vivo, even in case of noisy CAP data. The assumed FDD distribution regularizes the ill-conditioned inverse problem and produces good results.

  1. Predicting the potential distribution in China of Euwallacea fornicates (Eichhoff) under current and future climate conditions.

    Science.gov (United States)

    Ge, Xuezhen; Jiang, Chao; Chen, Linghong; Qiu, Shuang; Zhao, Yuxiang; Wang, Tao; Zong, Shixiang

    2017-04-19

    Euwallacea fornicatus (Eichhoff) is an important forest pest that has caused serious damage in America and Vietnam. In 2014, it attacked forests of Acer trialatum in the Yunnan province of China, creating concern in China's Forestry Bureau. We used the CLIMEX model to predict and compare the potential distribution for E. fornicates in China under current (1981-2010) and projected climate conditions (2011-2040) using one scenario (RCP8.5) and one global climate model (GCM), CSIRO-Mk3-6-0. Under both current and future climate conditions, the model predicted E. fornicates to be mainly distributed in the south of China. Comparing distributions under both climate conditions showed that the area of potential distribution was projected to increase (mainly because of an increase in favourable habitat) and shift to the north. Our results help clarify the potential effect of climate change on the range of this forest pest and provide a reference and guide to facilitate its control in China.

  2. Evaluation of protein adsorption onto a polyurethane nanofiber surface having different segment distributions

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Yuko; Koizumi, Gaku [Frontier Fiber Technology and Science, Graduate School of Engineering, University of Fukui (Japan); Sakamoto, Hiroaki, E-mail: hi-saka@u-fukui.ac.jp [Tenure-Track Program for Innovative Research, University of Fukui (Japan); Suye, Shin-ichiro [Frontier Fiber Technology and Science, Graduate School of Engineering, University of Fukui (Japan)

    2017-02-01

    Electrospinning is well known to be an effective method for fabricating polymeric nanofibers with a diameter of several hundred nanometers. Recently, the molecular-level orientation within nanofibers has attracted particular attention. Previously, we used atomic force microscopy to visualize the phase separation between soft and hard segments of a polyurethane (PU) nanofiber surface prepared by electrospinning. The unstretched PU nanofibers exhibited irregularly distributed hard segments, whereas hard segments of stretched nanofibers prepared with a high-speed collector exhibited periodic structures along the long-axis direction. PU was originally used to inhibit protein adsorption, but because the surface segment distribution was changed in the stretched nanofiber, here, we hypothesized that the protein adsorption property on the stretched nanofiber might be affected. We investigated protein adsorption onto PU nanofibers to elucidate the effects of segment distribution on the surface properties of PU nanofibers. The amount of adsorbed protein on stretched PU nanofibers was increased compared with that of unstretched nanofibers. These results indicate that the hard segment alignment on stretched PU nanofibers mediated protein adsorption. It is therefore expected that the amount of protein adsorption can be controlled by rotation of the collector. - Highlights: • The hard segments of stretched PU nanofibers exhibit periodic structures. • The adsorbed protein on stretched PU nanofibers was increased compared with PU film. • The hard segment alignment on stretched PU nanofibers mediated protein adsorption.

  3. Changes in snow distribution and surface topography following a snowstorm on Antarctic sea ice

    Science.gov (United States)

    Trujillo, Ernesto; Leonard, Katherine; Maksym, Ted; Lehning, Michael

    2016-11-01

    Snow distribution over sea ice is an important control on sea ice physical and biological processes. We combine measurements of the atmospheric boundary layer and blowing snow on an Antarctic sea ice floe with terrestrial laser scanning to characterize a typical storm and its influence on the spatial patterns of snow distribution at resolutions of 1-10 cm over an area of 100 m × 100 m. The pre-storm surface exhibits multidirectional elongated snow dunes formed behind aerodynamic obstacles. Newly deposited dunes are elongated parallel to the predominant wind direction during the storm. Snow erosion and deposition occur over 62% and 38% of the area, respectively. Snow deposition volume is more than twice that of erosion (351 m3 versus 158 m3), resulting in a modest increase of 2 ± 1 cm in mean snow depth, indicating a small net mass gain despite large mass relocation. Despite significant local snow depth changes due to deposition and erosion, the statistical distributions of elevation and the two-dimensional correlation functions remain similar to those of the pre-storm surface. Pre-storm and post-storm surfaces also exhibit spectral power law relationships with little change in spectral exponents. These observations suggest that for sea ice floes with mature snow cover features under conditions similar to those observed in this study, spatial statistics and scaling properties of snow surface morphology may be relatively invariant. Such an observation, if confirmed for other ice types and conditions, may be a useful tool for model parameterizations of the subgrid variability of sea ice surfaces.

  4. Effect of surface condition to temperature distribution in living tissue during cryopreservation

    Science.gov (United States)

    Nozawa, M.; Hatakeyama, S.; Sugimoto, Y.; Sasaki, H.

    2017-12-01

    The temperature distribution of the simulated living tissue is measured for the improvement of the cooling rate during cryopreservation when the surface condition of the test sample is changed by covering the stainless steel mesh. Agar is used as a simulated living tissue and is filled inside the test sample. The variation of the transient temperature with mesh by the directly immersion in the liquid nitrogen is measured. The temperatures on the sample surface and the inside of the sample are measured by use of type T thermocouples. It is confirmed that on the sample surface there is the slightly temperature increase than that in the saturated liquid nitrogen at the atmospheric pressure. It is found by the comparison of the degree of superheat with or without the mesh that the surface temperature of the test sample with the mesh is lower than that without the mesh. On the other hand, the time series variations of the temperature located in the center of the sample does not change with or without the mesh. It is considered that the center of the sample used is too deep from the surface to respond to the boiling state on the sample surface.

  5. Ecological niche and potential distribution of Anopheles arabiensis in Africa in 2050.

    Science.gov (United States)

    Drake, John M; Beier, John C

    2014-06-03

    The future distribution of malaria in Africa is likely to be much more dependent on environmental conditions than the current distribution due to the effectiveness of indoor and therapeutic anti-malarial interventions, such as insecticide-treated nets (ITNs), indoor residual spraying for mosquitoes (IRS), artemisinin-combination therapy (ACT), and intermittent presumptive treatment (IPT). Future malaria epidemiology is therefore expected to be increasingly dominated by Anopheles arabiensis, which is the most abundant exophagic mosquito competent to transmit Plasmodium falciparum and exhibits a wide geographic range. To map the potential distribution of An. arabiensis in Africa, ecological niche models were fit to 20th century collection records. Many common species distribution modelling techniques aim to discriminate species habitat from the background distribution of environments. Since these methods arguably result in unnecessarily large Type I and Type II errors, LOBAG-OC was used to identify the niche boundary using only data on An. arabiensis occurrences. The future distribution of An. arabiensis in Africa was forecasted by projecting the fit model onto maps of simulated climate change following three climate change scenarios. Ecological niche modelling revealed An. arabiensis to be a climate generalist in the sense that it can occur in most of Africa's contemporary environmental range. Under three climate change scenarios, the future distribution of An. arabiensis is expected to be reduced by 48%-61%. Map differences between baseline and projected climate suggest that habitat reductions will be especially extensive in Western and Central Africa; portions of Botswana, Namibia, and Angola in Southern Africa; and portions of Sudan, South Sudan, Somalia, and Kenya in East Africa. The East African Rift Valley and Eastern Coast of Africa are expected to remain habitable. Some modest gains in habitat are predicted at the margins of the current range in South Sudan

  6. Adsorption of a single polymer chain on a surface: effects of the potential range.

    Science.gov (United States)

    Klushin, Leonid I; Polotsky, Alexey A; Hsu, Hsiao-Ping; Markelov, Denis A; Binder, Kurt; Skvortsov, Alexander M

    2013-02-01

    We investigate the effects of the range of adsorption potential on the equilibrium behavior of a single polymer chain end-attached to a solid surface. The exact analytical theory for ideal lattice chains interacting with a planar surface via a box potential of depth U and width W is presented and compared to continuum model results and to Monte Carlo (MC) simulations using the pruned-enriched Rosenbluth method for self-avoiding chains on a simple cubic lattice. We show that the critical value U(c) corresponding to the adsorption transition scales as W(-1/ν), where the exponent ν=1/2 for ideal chains and ν≈3/5 for self-avoiding walks. Lattice corrections for finite W are incorporated in the analytical prediction of the ideal chain theory U(c)≈(π(2)/24)(W+1/2)(-2) and in the best-fit equation for the MC simulation data U(c)=0.585(W+1/2)(-5/3). Tail, loop, and train distributions at the critical point are evaluated by MC simulations for 1≤W≤10 and compared to analytical results for ideal chains and with scaling theory predictions. The behavior of a self-avoiding chain is remarkably close to that of an ideal chain in several aspects. We demonstrate that the bound fraction θ and the related properties of finite ideal and self-avoiding chains can be presented in a universal reduced form: θ(N,U,W)=θ(NU(c),U/U(c)). By utilizing precise estimations of the critical points we investigate the chain length dependence of the ratio of the normal and lateral components of the gyration radius. Contrary to common expectations this ratio attains a limiting universal value /=0.320±0.003 only at N~5000. Finite-N corrections for this ratio turn out to be of the opposite sign for W=1 and for W≥2. We also study the N dependence of the apparent crossover exponent φ(eff)(N). Strong corrections to scaling of order N(-0.5) are observed, and the extrapolated value φ=0.483±0.003 is found for all values of W. The strong correction to scaling effects found here explain why

  7. Evaluating wind energy potential in Gorgan–Iran using two methods of Weibull distribution function

    Directory of Open Access Journals (Sweden)

    Mehdi Hashemi-Tilehnoee

    2016-02-01

    Full Text Available In this study, wind energy characteristics of the, a city in northeast of Iran, measured at 10m height in 2014. The Gorgan airport one hour recorded data extrapolated to 50m height. The data have been statistically analyzed hourly, daily, monthly, seasonally and annually to determine the wind power potential. Weibull distribution function has been used to determine the wind power density and then the potential energy. Standard deviation method and power density method are the methods used to calculate the scaling and shaping parameters of the Weibull distribution function. The annual mean wind power calculated by the standard deviation method and the power density method is 38.98w/m2 and 41.32w/m2, respectively. By comparing the results concluded that the power density method is a better method than the standard deviation method. In addition, Gorgan wind energy potentiality categorized into class 1. So is unsuitable to utilize large wind energy turbine. Article History: Received November 21, 2015; Received in revised form January 15, 2016; Accepted February 10, 2016; Available online How to Cite This Article: Babayani, D., Khaleghi, M., Tashakor, S., and Hashemi-Tilehnoee.,M. (2016 Evaluating wind energy potential in Gorgan–Iran using two methods of Weibull distribution function. Int. Journal of Renewable Energy Development, 5(1, 43-48. http://dx.doi.org/10.14710/ijred.5.1.43-48 

  8. Codling Moth (Lepidoptera: Tortricidae) Establishment in China: Stages of Invasion and Potential Future Distribution

    Science.gov (United States)

    Zhu, Hongyu; Kumar, Sunil

    2017-01-01

    Abstract Codling moth (Cydia pomonella L.) is an internal feeding pest of apples and can cause substantial economic losses to fruit growers due to larval feeding which in turn degrades fruit quality and can result in complete crop loss if left uncontrolled. Although this pest originally developed in central Asia, it was not known to occur in China until 1953. For the first three decades the spread of codling moth within China was slow. Within the last three decades, addition of new commercial apple orchards and improved transportation, this pest has spread to over 131 counties in seven provinces in China. We developed regional (China) and global ecological niche models using MaxEnt to identify areas at highest potential risk of codling moth establishment and spread. Our objectives were to 1) predict the potential distribution of codling moth in China, 2) identify the important environmental factors associated with codling moth distribution in China, and 3) identify the different stages of invasion of codling moth in China. Human footprint, annual temperature range, precipitation of wettest quarter, and degree days ≥10 °C were the most important predictors associated with codling moth distribution. Our analysis identified areas where codling moth has the potential to establish, and mapped the different stages of invasion (i.e., potential for population stabilization, colonization, adaptation, and sink) of codling moth in China. Our results can be used in effective monitoring and management to stem the spread of codling moth in China. PMID:28973489

  9. A Universal Isotherm Model to Capture Adsorption Uptake and Energy Distribution of Porous Heterogeneous Surface

    KAUST Repository

    Ng, Kim Choon

    2017-08-31

    The adsorbate-adsorbent thermodynamics are complex as it is influenced by the pore size distributions, surface heterogeneity and site energy distribution, as well as the adsorbate properties. Together, these parameters defined the adsorbate uptake forming the state diagrams, known as the adsorption isotherms, when the sorption site energy on the pore surfaces are favorable. The available adsorption models for describing the vapor uptake or isotherms, hitherto, are individually defined to correlate to a certain type of isotherm patterns. There is yet a universal approach in developing these isotherm models. In this paper, we demonstrate that the characteristics of all sorption isotherm types can be succinctly unified by a revised Langmuir model when merged with the concepts of Homotattic Patch Approximation (HPA) and the availability of multiple sets of site energy accompanied by their respective fractional probability factors. The total uptake (q/q*) at assorted pressure ratios (P/P s ) are inextricably traced to the manner the site energies are spread, either naturally or engineered by scientists, over and across the heterogeneous surfaces. An insight to the porous heterogeneous surface characteristics, in terms of adsorption site availability has been presented, describing the unique behavior of each isotherm type.

  10. Predicting the potential geographical distribution of Rhodnius neglectus (Hemiptera, Reduviidae) based on ecological niche modeling.

    Science.gov (United States)

    Gurgel-Goncalves, Rodrigo; Cuba, César Augusto Cuba

    2009-07-01

    Rhodnius neglectus is frequently found in palm trees and bird nests in sylvatic environments. However, adult specimens infected by Trypanosoma cruzi have been invading houses in central Brazil. Analyzing and predicting the geographical distribution of this species may improve vector surveillance strategies for Chagas disease. Ecological niche modeling using the genetic algorithm for rule-set production (GARP) was applied to predict the geographical distribution of R. neglectus from occurrence records and a set of 23 predictor variables (e.g., temperature, precipitation, altitude, and vegetation). Additionally, the geographical distribution of R. neglectus was compared with the geographical distribution of four species of palm trees and two species of birds from the study region. The models were able to predict, with high probability, the occurrence of R. neglectus as a regular (although nonendemic) species of the Cerrado biome in central Brazil. Caatinga, Amazonian savanna, Pantanal, and the Bolivian Chaco appear as areas with lower probabilities of potential occurrence for the species. A great overlap was observed between the distribution of R. neglectus, palm trees (Acrocomia aculeata and Syagrus oleracea), and birds (Phacellodomus ruber and Pseudoseisura cristata). By including new records for R. neglectus (from both sylvatic and domestic environments), our study showed a distribution increase toward the west and northeast areas of Brazil in the "diagonal of open/dry ecoregions of South America". These results should aid Chagas disease vector surveillance programs, given that household invasion by Rhodnius species maintains the risk of disease transmission and limits control strategies.

  11. A Screen Space GPGPU Surface LIC Algorithm for Distributed Memory Data Parallel Sort Last Rendering Infrastructures

    Energy Technology Data Exchange (ETDEWEB)

    Loring, Burlen; Karimabadi, Homa; Rortershteyn, Vadim

    2014-07-01

    The surface line integral convolution(LIC) visualization technique produces dense visualization of vector fields on arbitrary surfaces. We present a screen space surface LIC algorithm for use in distributed memory data parallel sort last rendering infrastructures. The motivations for our work are to support analysis of datasets that are too large to fit in the main memory of a single computer and compatibility with prevalent parallel scientific visualization tools such as ParaView and VisIt. By working in screen space using OpenGL we can leverage the computational power of GPUs when they are available and run without them when they are not. We address efficiency and performance issues that arise from the transformation of data from physical to screen space by selecting an alternate screen space domain decomposition. We analyze the algorithm's scaling behavior with and without GPUs on two high performance computing systems using data from turbulent plasma simulations.

  12. Electrocardiogram: his bundle potentials can be recorded noninvasively beat by beat on surface electrocardiogram.

    Science.gov (United States)

    Wang, Gaopin; Liu, Renguang; Chang, Qinghua; Xu, Zhaolong; Zhang, Yingjie; Pan, Dianzhu

    2017-03-15

    The micro waveform of His bundle potential can't be recorded beat-to-beat on surface electrocardiogram yet. We have found that the micro-wavelets before QRS complex may be related to atrioventricular conduction system potentials. This study is to explore the possibility of His bundle potential can be noninvasively recorded on surface electrocardiogram. We randomized 65 patients undergoing radiofrequency catheter ablation of paroxysmal superventricular tachycardia (exclude overt Wolff-Parkinson-White syndrome) to receive "conventional electrocardiogram" and "new electrocardiogram" before the procedure. His bundle electrogram was collected during the procedure. Comparative analysis of PA s (PA interval recorded on surface electrocardiogram), AH s (AH interval recorded on surface electrocardiogram) and HV s (HV interval recorded on surface electrocardiogram) interval recorded on surface "new electrocardiogram" and PA, AH, HV interval recorded on His bundle electrogram was investigated. There was no difference (P > 0.05) between groups in HV s interval (49.63 ± 6.19 ms) and HV interval (49.35 ± 6.49 ms). Results of correlational analysis found that HV S interval was significantly positively associated with HV interval (r = 0.929; P electrocardiogram. Noninvasive His bundle potential tracing might represent a new method for locating the site of atrioventricular block and identifying the origin of a wide QRS complex.

  13. Axonal sodium channel distribution shapes the depolarized action potential threshold of dentate granule neurons.

    Science.gov (United States)

    Kress, Geraldine J; Dowling, Margaret J; Eisenman, Lawrence N; Mennerick, Steven

    2010-04-01

    Intrinsic excitability is a key feature dictating neuronal response to synaptic input. Here we investigate the recent observation that dentate granule neurons exhibit a more depolarized voltage threshold for action potential initiation than CA3 pyramidal neurons. We find no evidence that tonic GABA currents, leak or voltage-gated potassium conductances, or the expression of sodium channel isoform differences can explain this depolarized threshold. Axonal initial segment voltage-gated sodium channels, which are dominated by the Na(V)1.6 isoform in both cell types, distribute more proximally and exhibit lower overall density in granule neurons than in CA3 neurons. To test possible contributions of sodium channel distributions to voltage threshold and to test whether morphological differences participate, we performed simulations of dentate granule neurons and of CA3 pyramidal neurons. These simulations revealed that cell morphology and sodium channel distribution combine to yield the characteristic granule neuron action potential upswing and voltage threshold. Proximal axon sodium channel distribution strongly contributes to the higher voltage threshold of dentate granule neurons for two reasons. First, action potential initiation closer to the somatodendritic current sink causes the threshold of the initiating axon compartment to rise. Second, the proximity of the action potential initiation site to the recording site causes somatic recordings to more faithfully reflect the depolarized threshold of the axon than in cells like CA3 neurons, with distally initiating action potentials. Our results suggest that the proximal location of axon sodium channels in dentate granule neurons contributes to the intrinsic excitability differences between DG and CA3 neurons and may participate in the low-pass filtering function of dentate granule neurons. (c) 2009 Wiley-Liss, Inc.

  14. The Effect of Images on Surface Potential and Resistance Calculation of Grounding Systems

    Directory of Open Access Journals (Sweden)

    MARTINS, A.

    2015-05-01

    Full Text Available In the grounding systems with a two layers soil, the calculation of the surface potential using the image method is sometimes impossible due to singularities, avoiding researchers to use the method for electrodes in the bottom layer. In the literature this problem solution is refereed as unreliable or solved with other more complex methods. This paper presents a new approach to calculate the surface potentials in a two. layer soil, for electrodes in the bottom layer, when images are at surface. The singularities in computing surface voltage, when the first image upwards lies at surface, are analysed and it's shown that a small change in top layer thickness allows an approximate solution. Surface potentials due to grid conductor are also considered and the values of resistance are compared with those from other methodologies. Singularities for a ground rod that crosses the two layers are also treated. The obtained values of resistance are not satisfactory, due to lower segments images that overlap the upper segments. This paper also proposes shifting the surface of the upper part of the ground rod, in the upper layer, or taking the modulus of the mutual resistance, to overcome this difficulty.

  15. Pollution distribution of heavy metals in surface soil at an informal electronic-waste recycling site.

    Science.gov (United States)

    Fujimori, Takashi; Takigami, Hidetaka

    2014-02-01

    We studied distribution of heavy metals [lead (Pb), copper (Cu) and zinc (Zn)] in surface soil at an electronic-waste (e-waste) recycling workshop near Metro Manila in the Philippines to evaluate the pollution size (spot size, small area or the entire workshop), as well as to assess heavy metal transport into the surrounding soil environment. On-site length-of-stride-scale (~70 cm) measurements were performed at each surface soil point using field-portable X-ray fluorescence (FP-XRF). The surface soil at the e-waste recycling workshop was polluted with Cu, Zn and Pb, which were distributed discretely in surface soil. The site was divided into five areas based on the distance from an entrance gate (y-axis) of the e-waste recycling workshop. The three heavy metals showed similar concentration gradients in the y-axis direction. Zn, Pb and Cu concentrations were estimated to decrease to half of their maximum concentrations at ~3, 7 and 7 m from the pollution spot, respectively, inside the informal e-waste recycling workshop. Distance from an entrance may play an important role in heavy metal transport at the soil surface. Using on-site FP-XRF, we evaluated the metal ratio to characterise pollution features of the solid surface. Variability analysis of heavy metals revealed vanishing surficial autocorrelation over metre ranges. Also, the possibility of concentration prediction at unmeasured points using geostatistical kriging was evaluated, and heavy metals had a relative "small" pollution scales and remained inside the original workshop compared with toxic organohalogen compounds. Thus, exposure to heavy metals may directly influence the health of e-waste workers at the original site rather than the surrounding habitat and environmental media.

  16. Comparison of Degrees of Potential-Energy-Surface Anharmonicity for Complexes and Clusters with Hydrogen Bonds

    Science.gov (United States)

    Kozlovskaya, E. N.; Doroshenko, I. Yu.; Pogorelov, V. E.; Vaskivskyi, Ye. V.; Pitsevich, G. A.

    2018-01-01

    Previously calculated multidimensional potential-energy surfaces of the MeOH monomer and dimer, water dimer, malonaldehyde, formic acid dimer, free pyridine-N-oxide/trichloroacetic acid complex, and protonated water dimer were analyzed. The corresponding harmonic potential-energy surfaces near the global minima were constructed for series of clusters and complexes with hydrogen bonds of different strengths based on the behavior of the calculated multidimensional potential-energy surfaces. This enabled the introduction of an obvious anharmonicity parameter for the calculated potential-energy surfaces. The anharmonicity parameter was analyzed as functions of the size of the analyzed area near the energy minimum, the number of points over which energies were compared, and the dimensionality of the solved vibrational problem. Anharmonicity parameters for potential-energy surfaces in complexes with strong, medium, and weak H-bonds were calculated under identical conditions. The obtained anharmonicity parameters were compared with the corresponding diagonal anharmonicity constants for stretching vibrations of the bridging protons and the lengths of the hydrogen bridges.

  17. A new potential surface and quasiclassical trajectory study of H+H2O→OH+H2

    International Nuclear Information System (INIS)

    Wu, Guo-sheng; Schatz, George C.; Lendvay, G.; Fang, De-Cai; Harding, L. B.

    2000-01-01

    We present a method for developing potential-energy surfaces for abstraction reactions with four or more atoms which combines spline fits to high quality ab initio results for the three degrees of freedom that are most active in the reaction (two stretches and a bend) with simple empirical functions (Morse stretches, cosine bends, and torsions) for the spectator variables. The geometry and force constants associated with the spectator modes are allowed to vary along the reaction path so as to match stationary point properties from the ab initio calculations. In an application of this approach to the H+H 2 O reaction, we are able to generate a global surface for the H 3 O system that accurately matches ab initio properties, and is globally smooth and free of artifacts. Quasiclassical trajectory (QCT) calculations are used with this surface to study the H+H 2 O reaction dynamics for both the ground and local mode excited states. The resulting ground-state angular distributions, product state vibrational and rotational distributions, and rotational alignment factors are in excellent agreement with all known experiments. This represents an improvement over the results obtained using previous surfaces, but like the past surfaces, the calculated integral cross sections are below experiment by at least a factor of 2. For studies of the H+H 2 O reaction involving local mode excited states of water, the new surface is consistent with ab initio threshold behavior, with the (04) - local mode state having zero activation energy. However the reactive rate coefficients are substantially smaller than the observed total reactive plus inelastic rate coefficient. This indicates that recent experiments due to Barnes, Sharkey, Sims, and Smith are dominated by energy transfer rather than reaction. (c) 2000 American Institute of Physics

  18. Optically pumped vertical-cavity surface-emitting laser at 374.9 nm with an electrically conducting n-type distributed Bragg reflector

    Science.gov (United States)

    Liu, Yuh-Shiuan; Saniul Haq, Abul Fazal Muhammad; Mehta, Karan; Kao, Tsung-Ting; Wang, Shuo; Xie, Hongen; Shen, Shyh-Chiang; Yoder, P. Douglas; Ponce, Fernando A.; Detchprohm, Theeradetch; Dupuis, Russell D.

    2016-11-01

    An optically pumped vertical-cavity surface-emitting laser with an electrically conducting n-type distributed Bragg reflector was achieved at 374.9 nm. An epitaxially grown 40-pair n-type AlGaN/GaN distributed Bragg reflector was used as the bottom mirror, while the top mirror was formed by a dielectric distributed Bragg reflector composed of seven pairs of HfO2/SiO2. A numerical simulation for the optical mode clearly demonstrated that a high confinement factor was achieved and the threshold pumping power density at room temperature was measured as 1.64 MW/cm2. The achieved optically pumped laser demonstrates the potential of utilizing an n-type distributed Bragg reflector for surface-emitting optical devices.

  19. High volume hydraulic fracturing operations: potential impacts on surface water and human health.

    Science.gov (United States)

    Mrdjen, Igor; Lee, Jiyoung

    2016-08-01

    High volume, hydraulic fracturing (HVHF) processes, used to extract natural gas and oil from underground shale deposits, pose many potential hazards to the environment and human health. HVHF can negatively affect the environment by contaminating soil, water, and air matrices with potential pollutants. Due to the relatively novel nature of the process, hazards to surface waters and human health are not well known. The purpose of this article is to link the impacts of HVHF operations on surface water integrity, with human health consequences. Surface water contamination risks include: increased structural failure rates of unconventional wells, issues with wastewater treatment, and accidental discharge of contaminated fluids. Human health risks associated with exposure to surface water contaminated with HVHF chemicals include increased cancer risk and turbidity of water, leading to increased pathogen survival time. Future research should focus on modeling contamination spread throughout the environment, and minimizing occupational exposure to harmful chemicals.

  20. Self-consistent density functional calculation of the image potential at a metal surface

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Alvarellos, J E [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Chacon, E [Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); GarcIa-Gonzalez, P [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain)

    2007-07-04

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z{sub 0}), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z{sub 0}, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.

  1. Self-consistent density functional calculation of the image potential at a metal surface

    International Nuclear Information System (INIS)

    Jung, J; Alvarellos, J E; Chacon, E; GarcIa-Gonzalez, P

    2007-01-01

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z 0 ), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z 0 , and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description

  2. Data documenting the potential distribution of Aedes aegypti in the center of Veracruz, Mexico

    Directory of Open Access Journals (Sweden)

    Israel Estrada-Contreras

    2017-02-01

    Full Text Available The data presented in this article are related to the research article entitled “Establishment of Aedes aegypti (L. in mountainous regions in Mexico: Increasing number of population at risk of mosquito-borne disease and future climate conditions” (M. Equihua, S. Ibáñez-Bernal, G. Benítez, I. Estrada-Contreras, C.A. Sandoval-Ruiz, F.S. Mendoza-Palmero, 2016 [1]. This article provides presence records in shapefile format used to generate maps of potential distribution of Aedes aegypti with different climate change scenarios as well as each of the maps obtained in raster format. In addition, tables with values of potential distribution of the vector as well as the average values of probability of presence including data of the mosquito incidence along the altitudinal range.

  3. The potential natural vegetation of eastern Africa distribution, conservation and future changes

    DEFF Research Database (Denmark)

    van Breugel, Paulo

    perspectives. Chapter 2 presents a biogeographic study of a hitherto poorly studied vegetation type in Ethiopia which is characterized by many near-endemic or endemic species. Chapter 3 focusses on the distribution of fire and different potential vegetation types in Ethiopia under current climatic conditions...... and sustainable management of the natural environment. There is therefore an urgent need for information that allow us to assess the current status of the region’s natural environment and to predict how this may change under future climates. This thesis aims to improve our knowledge on natural vegetation...... distribution in eastern African, examine how this may change under future climates, and how this can be used to identify conservation priorities in the region. Chapter 1 presents a brief overview of the concept of the potential natural vegetation (PNV), synthesizes the general findings and discusses future...

  4. Generalized parton distributions: confining potential effects within AdS/QCD

    Energy Technology Data Exchange (ETDEWEB)

    Traini, Marco [Universite Paris Saclay, CEA, Institut de Physique Theorique, Gif-sur-Yvette (France); Universita degli Studi di Trento, Dipartimento di Fisica, Trento (Italy); INFN-TIFPA, Trento (Italy)

    2017-04-15

    Generalized parton distributions are investigated within a holographic approach where the string modes in the fifth dimension describe the nucleon in a bottom-up or AdS/QCD framework. The aim is to bring the AdS/QCD results in the realm of phenomenology in order to extract consequences and previsions. Two main aspects are studied: (i) the role of the confining potential needed for breaking conformal invariance and introducing confinement (both: classic soft-wall and recent infra-red potentials are investigated); (ii) the extension of the predicted GPDs to the entire range of off-forward kinematics by means of double distributions. Higher Fock states are included describing the nucleon as a superposition of three valence quarks and quark-antiquark pairs and gluons. (orig.)

  5. [Effect of pulse magnetic field on distribution of neuronal action potential].

    Science.gov (United States)

    Zheng, Yu; Cai, Di; Wang, Jin-Hai; Li, Gang; Lin, Ling

    2014-08-25

    The biological effect on the organism generated by magnetic field is widely studied. The present study was aimed to observe the change of sodium channel under magnetic field in neurons. Cortical neurons of Kunming mice were isolated, subjected to 15 Hz, 1 mT pulse magnetic stimulation, and then the currents of neurons were recorded by whole-cell patch clamp. The results showed that, under magnetic stimulation, the activation process of Na(+) channel was delayed, and the inactivation process was accelerated. Given the classic three-layer model, the polarization diagram of cell membrane potential distribution under pulse magnetic field was simulated, and it was found that the membrane potential induced was associated with the frequency and intensity of magnetic field. Also the effect of magnetic field-induced current on action potential was simulated by Hodgkin-Huxley (H-H) model. The result showed that the generation of action potential was delayed, and frequency and the amplitudes were decreased when working current was between -1.32 μA and 0 μA. When the working current was higher than 0 μA, the generation frequency of action potential was increased, and the change of amplitudes was not obvious, and when the working current was lower than -1.32 μA, the time of rising edge and amplitudes of action potential were decreased drastically, and the action potential was unable to generate. These results suggest that the magnetic field simulation can affect the distribution frequency and amplitude of action potential of neuron via sodium channel mediation.

  6. MRD-CI potential surfaces using balanced basis sets. IV. The H2 molecule and the H3 surface

    International Nuclear Information System (INIS)

    Wright, J.S.; Kruus, E.

    1986-01-01

    The utility of midbond functions in molecular calculations was tested in two cases where the correct results are known: the H 2 potential curve and the collinear H 3 potential surface. For H 2 , a variety of basis sets both with and without bond functions was compared to the exact nonrelativistic potential curve of Kolos and Wolniewicz [J. Chem. Phys. 43, 2429 (1965)]. It was found that optimally balanced basis sets at two levels of quality were the double zeta single polarization plus sp bond function basis (BF1) and the triple zeta double polarization plus two sets of sp bond function basis (BF2). These gave bond dissociation energies D/sub e/ = 4.7341 and 4.7368 eV, respectively (expt. 4.7477 eV). Four basis sets were tested for basis set superposition errors, which were found to be small relative to basis set incompleteness and therefore did not affect any conclusions regarding basis set balance. Basis sets BF1 and BF2 were used to construct potential surfaces for collinear H 3 , along with the corresponding basis sets DZ*P and TZ*PP which contain no bond functions. Barrier heights of 12.52, 10.37, 10.06, and 9.96 kcal/mol were obtained for basis sets DZ*P, TZ*PP, BF1, and BF2, respectively, compared to an estimated limiting value of 9.60 kcal/mol. Difference maps, force constants, and relative rms deviations show that the bond functions improve the surface shape as well as the barrier height

  7. The Low-Noise Potential of Distributed Propulsion on a Catamaran Aircraft

    Science.gov (United States)

    Posey, Joe W.; Tinetti, A. F.; Dunn, M. H.

    2006-01-01

    The noise shielding potential of an inboard-wing catamaran aircraft when coupled with distributed propulsion is examined. Here, only low-frequency jet noise from mid-wing-mounted engines is considered. Because low frequencies are the most difficult to shield, these calculations put a lower bound on the potential shielding benefit. In this proof-of-concept study, simple physical models are used to describe the 3-D scattering of jet noise by conceptualized catamaran aircraft. The Fast Scattering Code is used to predict noise levels on and about the aircraft. Shielding results are presented for several catamaran type geometries and simple noise source configurations representative of distributed propulsion radiation. Computational analyses are presented that demonstrate the shielding benefits of distributed propulsion and of increasing the width of the inboard wing. Also, sample calculations using the FSC are presented that demonstrate additional noise reduction on the aircraft fuselage by the use of acoustic liners on the inboard wing trailing edge. A full conceptual aircraft design would have to be analyzed over a complete mission to more accurately quantify community noise levels and aircraft performance, but the present shielding calculations show that a large acoustic benefit could be achieved by combining distributed propulsion and liner technology with a twin-fuselage planform.

  8. Permutation invariant potential energy surfaces for polyatomic reactions using atomistic neural networks

    International Nuclear Information System (INIS)

    Kolb, Brian; Zhao, Bin; Guo, Hua; Li, Jun; Jiang, Bin

    2016-01-01

    The applicability and accuracy of the Behler-Parrinello atomistic neural network method for fitting reactive potential energy surfaces is critically examined in three systems, H + H 2 → H 2 + H, H + H 2 O → H 2 + OH, and H + CH 4 → H 2 + CH 3 . A pragmatic Monte Carlo method is proposed to make efficient choice of the atom-centered mapping functions. The accuracy of the potential energy surfaces is not only tested by fitting errors but also validated by direct comparison in dynamically important regions and by quantum scattering calculations. Our results suggest this method is both accurate and efficient in representing multidimensional potential energy surfaces even when dissociation continua are involved.

  9. Image potential resonances of the aluminum (100) surface; Bildpotentialresonanzen der Aluminium-(100)-Oberflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Winter, Matthias

    2011-07-08

    Image-potential resonances on the (100) surface of pure Aluminum are investigated experimentally and theoretically. The experiments are conducted both energy- and time-resolved using the method of two-photon photoemission spectroscopy. The main attention of the theoretical examination and extensive numerical calculations is devoted to the interaction between surface and bulk states. Image-potential resonances on Al(100) are a system in which a complete series of discrete Rydberg states strongly couples to a continuum of states. As a simple metal it also provides a good opportunity to test theoretical models of the structure of the potential at metal surfaces. This work represents the first high-resolution investigation of image-potential resonances with such strong resonance character. For the first time, it is demonstrated experimentally that isolated image-potential resonances exist on an Aluminum surface. On the (100) surface of Aluminum the second through fifth image-potential resonance are resolved and both, their energies and lifetimes are measured. The binding energies of the image-potential resonances form a Rydberg series of states {epsilon}{sub n}=-(0,85 eV)/((n+a){sup 2}). Within the accuracy of the measurement it is not necessary to introduce a quantum defect a (a=0.022{+-}0.035). Using angle-resolved two-photon photoemission spectroscopy the effective mass of electrons in the second image-potential resonance is measured to 1.01{+-}0.11 electron masses. The lifetimes of the resonances increase as {tau}{sub n} = (1.0{+-}0.2)fs.n{sup 3} starting from n=2. Calculations using the density matrix formalism show that the experimentally observed lifetimes can be explained well by electrons decaying into the bulk. The effect of resonance trapping leads to extended lifetimes in the process. Contrary to common theoretical models of image-potential states at metal surfaces the first image-potential resonance cannot be observed in two-photon photoemission on Al(100

  10. [Distributions of phosphorus fractions in suspended sediments and surface sediments of Tiaoxi mainstreams and cause analysis].

    Science.gov (United States)

    Chen, Hai-Long; Yuan, Xu-Yin; Wang, Huan; Li, Zheng-Yang; Xu, Hai-Yan

    2015-02-01

    Phosphorus is a primary nutrient showing the water quality status of river and inducing eutrophication, and a different phosphorus fraction can make diverse contributions to water quality. Four phosphorus forms of suspended sediments and surface sediments in Tiaoxi mainstreams were measured using a sequential extraction procedure, and the distributions of their forms were discussed. The results showed that the tropic status of Xitiaoxi River was inferior to that of Dongtiaoxi River as a whole, and the water quality in the middle reach of Dongtiaoxi River was better than that in the upper and lower reaches. The contents of nutrient elements in suspended sediments were significantly higher than those in surface sediment, which indicated an enrichment of nutrient in fine sediment. The percentages of the loosely absorbed phosphorus ( NH4Cl-P), the reductant phosphorus (BD-P) and the metal oxide bound phosphorus (NaOH-P) in the suspended sediment were higher than those in surface sediment, while the percentage of the calcium bound phosphorus (HCl-P) showed a reverse trend. Correlation analyses between phosphorus forms and chemical compositions of suspended sediments and surface sediments were performed. The results showed the phosphorus forms in suspended sediments and surface sediments of Xitiaoxi River had weak relationships with mineral components, while those in the Dongtiaoxi River had strong relationships with mineral, especially OM and clay mineral. The cause was associated with the geological setting and material sources in Tiaoxi watershed.

  11. Modelling the potential distribution of Bemisia tabaci in Europe in light of the climate change scenario.

    Science.gov (United States)

    Gilioli, Gianni; Pasquali, Sara; Parisi, Simone; Winter, Stephan

    2014-10-01

    Bemisia tabaci is a serious pest of agricultural and horticultural crops in greenhouses and fields around the world. This paper deals with the distribution of the pest under field conditions. In Europe, the insect is currently found in coastal regions of Mediterranean countries where it is subject to quarantine regulations. To assess the risk presented by B. tabaci to Europe, the area of potential establishment of this insect, in light of the climate change scenario, was assessed by a temperature-dependent physiologically based demographic model (PBDM). The simulated potential distribution under current climate conditions has been successfully validated with the available field records of B. tabaci in Europe. Considering climate change scenarios of +1 and +2 °C, range expansion by B. tabaci is predicted, particularly in Spain, France, Italy, Greece and along the Adriatic coast of the Balkans. Nonetheless, even under the scenario of +2 °C, northern European countries are not likely to be at risk of B. tabaci establishment because of climatic limitations. Model validation with field observations and evaluation of uncertainties associated with model parameter variability support the reliability of model results. The PBDM developed here can be applied to other organisms and offers significant advantages for assessing the potential distribution of invasive species. © 2014 Society of Chemical Industry.

  12. The impacts of racial group membership on people's distributive justice: an event-related potential study.

    Science.gov (United States)

    Wang, Yan; Tang, Yi-Yuan; Deng, Yuqin

    2014-04-16

    How individuals and societies distribute benefits has long been studied by psychologists and sociologists. Previous work has highlighted the importance of social identity on people's justice concerns. However, it is not entirely clear how racial in-group/out-group relationship affects the brain activity in distributive justice. In this study, event-related potentials were recorded while participants made their decisions about donation allocation. Behavioral results showed that racial in-group factor affected participants' decisions on justice consideration. Participants were more likely to make relatively equity decisions when racial in-group factor was congruent with equity compared with the corresponding incongruent condition. Moreover, this incongruent condition took longer response times than congruent condition. Meanwhile, less equity decisions were made when efficiency was larger in the opposite side to equity than it was equal between the two options. Scalp event-related potential analyses revealed that greater P300 and late positive potential amplitudes were elicited by the incongruent condition compared with the congruent condition. These findings suggest that the decision-making of distributive justice could be modulated by racial group membership, and greater attentional resources or cognitive efforts are required when racial in-group factor and equity conflict with each other.

  13. Single-ion and pair-interaction potentials near simple metal surfaces

    International Nuclear Information System (INIS)

    Barnett, R.N.; Barrera, R.G.; Cleveland, C.L.; Landman, U.

    1983-01-01

    Presented is a model for semi-infinite simple metals which does not require crystalline order or a single species, and thus is applicable to problems of defect energetics near the surface and random-alloy surfaces as well as ideal metal surfaces. The formulation is based on the use of ionic pseudopotentials and linear-response theory. An expression for the total energy is obtained which depends explicitly on ionic species and position. This expression is decomposed into a density-dependent term and single-ion and ionic pair-interaction potential terms. The single-ion potentials oscillate about a constant bulk value, with the magnitude of the oscillation decreasing rapidly away from the surface. The interaction between pairs of ions near the surface is shown to be a noncentral force interaction which differs significantly from the central-force bulk pair potential. The effect of quantum interference in the response of the semi-infinite electron gas to the ions is seen in both the single-ion and the pair-interaction potentials. Results are presented for the simple metals sodium, potassium, and rubidium

  14. Processing statistics: an examination of focused and distributed attention using event related potentials.

    Science.gov (United States)

    Baijal, Shruti; Nakatani, Chie; van Leeuwen, Cees; Srinivasan, Narayanan

    2013-06-07

    Human observers show remarkable efficiency in statistical estimation; they are able, for instance, to estimate the mean size of visual objects, even if their number exceeds the capacity limits of focused attention. This ability has been understood as the result of a distinct mode of attention, i.e. distributed attention. Compared to the focused attention mode, working memory representations under distributed attention are proposed to be more compressed, leading to reduced working memory loads. An alternate proposal is that distributed attention uses less structured, feature-level representations. These would fill up working memory (WM) more, even when target set size is low. Using event-related potentials, we compared WM loading in a typical distributed attention task (mean size estimation) to that in a corresponding focused attention task (object recognition), using a measure called contralateral delay activity (CDA). Participants performed both tasks on 2, 4, or 8 different-sized target disks. In the recognition task, CDA amplitude increased with set size; notably, however, in the mean estimation task the CDA amplitude was high regardless of set size. In particular for set-size 2, the amplitude was higher in the mean estimation task than in the recognition task. The result showed that the task involves full WM loading even with a low target set size. This suggests that in the distributed attention mode, representations are not compressed, but rather less structured than under focused attention conditions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Spatial distribution of heterocyclic organic matter compounds at macropore surfaces in Bt-horizons

    Science.gov (United States)

    Leue, Martin; Eckhardt, Kai-Uwe; Gerke, Horst H.; Ellerbrock, Ruth H.; Leinweber, Peter

    2017-04-01

    The illuvial Bt-horizon of Luvisols is characterized by coatings of clay and organic matter (OM) at the surfaces of cracks, biopores and inter-aggregate spaces. The OM composition of the coatings that originate from preferential transport of suspended matter in macropores determines the physico-chemical properties of the macropore surfaces. The analysis of the spatial distribution of specific OM components such as heterocyclic N-compounds (NCOMP) and benzonitrile and naphthalene (BN+NA) could enlighten the effect of macropore coatings on the transport of colloids and reactive solutes during preferential flow and on OM turnover processes in subsoils. The objective was to characterize the mm-to-cm scale spatial distribution of NCOMP and BN+NA at intact macropore surfaces from the Bt-horizons of two Luvisols developed on loess and glacial till. In material manually separated from macropore surfaces the proportions of NCOMP and BN+NA were determined by pyrolysis-field ionization mass spectrometry (Py-FIMS). These OM compounds, likely originating from combustion residues, were found increased in crack coatings and pinhole fillings but decreased in biopore walls (worm burrows and root channels). The Py-FIMS data were correlated with signals from C=O and C=C groups and with signals from O-H groups of clay minerals as determined by Fourier transform infrared spectroscopy in diffuse reflectance mode (DRIFT). Intensive signals of C15 to C17 alkanes from long-chain alkenes as main components of diesel and diesel exhaust particulates substantiated the assumption that burning residues were prominent in the subsoil OM. The spatial distribution of NCOMP and BN+NA along the macropores was predicted by partial least squares regression (PLSR) using DRIFT mapping spectra from intact surfaces and was found closely related to the distribution of crack coatings and pinholes. The results emphasize the importance of clay coatings in the subsoil to OM sorption and stabilization

  16. Abundance and Distribution Characteristics of Microplastics in Surface Seawaters of the Incheon/Kyeonggi Coastal Region.

    Science.gov (United States)

    Chae, Doo-Hyeon; Kim, In-Sung; Kim, Seung-Kyu; Song, Young Kyoung; Shim, Won Joon

    2015-10-01

    Microplastics in marine environments are of emerging concern due to their widespread distribution, their ingestion by various marine organisms, and their roles as a source and transfer vector of toxic chemicals. However, our understanding of their abundance and distribution characteristics in surface seawater (SSW) remains limited. We investigated microplastics in the surface microlayer (SML) and the SSW at 12 stations near-shore and offshore of the Korean west coast, Incheon/Kyeonggi region. Variation between stations, sampling media, and sampling methods were compared based on abundances, size distribution, and composition profiles of microsized synthetic polymer particles. The abundance of microplastics was greater in the SML (152,688 ± 92,384 particles/m(3)) than in SSW and showed a significant difference based on the sampling method for SSWs collected using a hand net (1602 ± 1274 particles/m(3)) and a zooplankton trawl net (0.19 ± 0.14 particles/m(3)). Ship paint particles (mostly alkyd resin polymer) accounted for the majority of microplastics detected in both SML and SSWs, and increased levels were observed around the voyage routes of large vessels. This indicates that polymers with marine-based origins become an important contributor to microplastics in coastal SSWs of this coastal region.

  17. Multispectral UV imaging for surface analysis of MUPS tablets with special focus on the pellet distribution.

    Science.gov (United States)

    Novikova, Anna; Carstensen, Jens M; Rades, Thomas; Leopold, Prof Dr Claudia S

    2016-12-30

    In the present study the applicability of multispectral UV imaging in combination with multivariate image analysis for surface evaluation of MUPS tablets was investigated with respect to the differentiation of the API pellets from the excipients matrix, estimation of the drug content as well as pellet distribution, and influence of the coating material and tablet thickness on the predictive model. Different formulations consisting of coated drug pellets with two coating polymers (Aquacoat ® ECD and Eudragit ® NE 30 D) at three coating levels each were compressed to MUPS tablets with various amounts of coated pellets and different tablet thicknesses. The coated drug pellets were clearly distinguishable from the excipients matrix using a partial least squares approach regardless of the coating layer thickness and coating material used. Furthermore, the number of the detected drug pellets on the tablet surface allowed an estimation of the true drug content in the respective MUPS tablet. In addition, the pellet distribution in the MUPS formulations could be estimated by UV image analysis of the tablet surface. In conclusion, this study revealed that UV imaging in combination with multivariate image analysis is a promising approach for the automatic quality control of MUPS tablets during the manufacturing process. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Dose distribution considerations of medium energy electron beams at extended source-to-surface distance

    International Nuclear Information System (INIS)

    Saw, Cheng B.; Ayyangar, Komanduri M.; Pawlicki, Todd; Korb, Leroy J.

    1995-01-01

    Purpose: To determine the effects of extended source-to-surface distance (SSD) on dose distributions for a range of medium energy electron beams and cone sizes. Methods and Materials: The depth-dose curves and isodose distributions of 6 MeV, 10 MeV, and 14 MeV electron beams from a dual photon and multielectron energies linear accelerator were studied. To examine the influence of cone size, the smallest and the largest cone sizes available were used. Measurements were carried out in a water phantom with the water surface set at three different SSDs from 101 to 116 cm. Results: In the region between the phantom surface and the depth of maximum dose, the depth-dose decreases as the SSD increases for all electron beam energies. The effects of extended SSD in the region beyond the depth of maximum dose are unobservable and, hence, considered minimal. Extended SSD effects are apparent for higher electron beam energy with small cone size causing the depth of maximum dose and the rapid dose fall-off region to shift deeper into the phantom. However, the change in the depth-dose curve is small. On the other hand, the rapid dose fall-off region is essentially unaltered when the large cone is used. The penumbra enlarges and electron beam flatness deteriorates with increasing SSD

  19. Distribution of potential eye and tissue donors within an Australian teaching hospital.

    Science.gov (United States)

    Dutch, Martin J; Denahy, Anthony F

    2017-12-11

    Eye and Tissue donation has the capacity to transform lives, yet the vast majority of potential in-hospital donors are not recognised. Studies which describe the relative importance of specific units or wards in determining the size of the donor pool are limited. The aim of this study was to map the distribution of potential Eye and Tissue donors within the study hospital. A 12-month retrospective analysis of all patient deaths at the study hospital was undertaken. The ability to donate corneal, heart valve, bone and skin tissue was investigated. Patients were classified as potential donors if they met specific age criteria and had an absence of contraindications based on electronic database search. There were 985 deaths during the study period. Deaths occurred under the care of 26 separate clinical units, and within 28 unique wards and treatment spaces. Four hundred and forty nine (45.6%) patients were identified as potential eye or tissue donors. The majority of potential donors occurred in ICU, Emergency and palliative care units. Of the subset of 328 deaths ≤ 70 years, the frequency of potential tissue donors was 55% (n = 181). ED and ICU had significantly higher frequencies of potential donor than other wards (86 and 77%, p Donors within our hospital. These will provide an important focus for future interventions to improve the rate of eye and tissue donation.

  20. Contrasting the surface ocean distribution of bromoform and methyl iodide; implications for boundary layer physics, chemistry and climate

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, C J, E-mail: carl.j.palmer@gmail.co [Department of Oceanography, University of Cape Town, 7701 (South Africa)

    2010-08-15

    Bromoform and methyl iodide are both methane-like hydrocarbons with a halogen atom replacing one or more of the hydrogen atoms. Both of these compounds occur naturally in the environment as a result of their production from seaweed and kelp. They are of interest to climate science as a result of their catalytic destruction of boundary layer ozone (a potent greenhouse gas) and, specifically for methyl iodide, the proposed role in the formation of new cloud condensation nuclei with implications for climate. In this paper, the currently available data on the distribution of bromoform and methyl iodide are analysed and contrasted to show that the concentrations of bromoform and methyl iodide do not correlate, that, in contrast to bromoform, the parameterization of sea surface methyl iodide concentrations demands only the sea surface temperature, and that the pelagic distribution of methyl iodide appears to follow the solar zenith angle. These three observations together suggest that, while the pelagic source of bromoform is mostly biogenic, the source of methyl iodide is photochemical. This has implications for the understanding of planetary boundary layer chemistry and potential organohalogen mediated feedbacks to climate.

  1. Spatial distribution of the electrical potential and ion concentration in the downstream area of atmospheric pressure remote plasma

    Directory of Open Access Journals (Sweden)

    M. V. Mishin

    2014-10-01

    Full Text Available This paper presents the results from an experimental study of the ion flux characteristics behind the remote plasma zone in a vertical tube reaction chamber for atmospheric pressure plasma enhanced chemical vapor deposition. Capacitively coupled radio frequency plasma was generated in pure He and gas mixtures: He–Ar, He–O2, He–TEOS. We previously used the reaction system He–TEOS for the synthesis of self-assembled structures of silicon dioxide nanoparticles. It is likely that the electrical parameters of the area, where nanoparticles have been transported from the synthesis zone to the substrate, play a significant role in the self-organization processes both in the vapor phase and on the substrate surface. The results from the spatial distribution of the electrical potential and ion concentration in the discharge downstream area measured by means of the external probe of original design and the special data processing method are demonstrated in this work. Positive and negatives ions with maximum concentrations of 106–107 cm−3 have been found at 10–80 mm distance behind the plasma zone. On the basis of the revealed distributions for different gas mixtures, the physical model of the observed phenomena is proposed. The model illustrates the capability of the virtual ion emitter formation behind the discharge gap and the presence of an extremum of the electrical potential at the distance of approximately 10−2–10−1 mm from the grounded electrode.

  2. Study on the distribution of streaming potential while groundwater pumping up; Chikasui no kumiage ni tomonau ryudo den`i hassei ni kansuru kento

    Energy Technology Data Exchange (ETDEWEB)

    Sato, H.; Shima, H.; Sakurai, K. [OYO Corp., Tokyo (Japan)

    1997-10-22

    This paper describes effectiveness of water channel prospecting by means of streaming potential method. To investigate the distribution of streaming potential on the ground surface while groundwater pumping up, some laboratory experiments were performed. A system was constructed, in which fluid is flowed in an experimental cistern from its both ends and self-flowed through a strainer pipe fixed for flowing out the fluid at the center of the cistern. Streaming potential with the flowing of the fluid was observed. Positive streaming potential waveform was generated with the flowing of the fluid, and the potential increased with approaching the strainer pipe. A groundwater pumping test facility was used as a field test site. There was a positive maximal point of potential distribution at about 30 m far from the pumping well in the southeast direction. The potential gradually decreased in the eastern part from the maximal point. The potential steeply decreased in the northwest direction from the pumping well. From these experiments, it was found that the groundwater flow and underground structures can be reflected by the distribution of streaming potential, and that the present method is effective for water channel prospecting. 3 refs., 8 figs.

  3. Potential Distribution Predicted for Rhynchophorus ferrugineus in China under Different Climate Warming Scenarios.

    Directory of Open Access Journals (Sweden)

    Xuezhen Ge

    Full Text Available As the primary pest of palm trees, Rhynchophorus ferrugineus (Olivier (Coleoptera: Curculionidae has caused serious harm to palms since it first invaded China. The present study used CLIMEX 1.1 to predict the potential distribution of R. ferrugineus in China according to both current climate data (1981-2010 and future climate warming estimates based on simulated climate data for the 2020s (2011-2040 provided by the Tyndall Center for Climate Change Research (TYN SC 2.0. Additionally, the Ecoclimatic Index (EI values calculated for different climatic conditions (current and future, as simulated by the B2 scenario were compared. Areas with a suitable climate for R. ferrugineus distribution were located primarily in central China according to the current climate data, with the northern boundary of the distribution reaching to 40.1°N and including Tibet, north Sichuan, central Shaanxi, south Shanxi, and east Hebei. There was little difference in the potential distribution predicted by the four emission scenarios according to future climate warming estimates. The primary prediction under future climate warming models was that, compared with the current climate model, the number of highly favorable habitats would increase significantly and expand into northern China, whereas the number of both favorable and marginally favorable habitats would decrease. Contrast analysis of EI values suggested that climate change and the density of site distribution were the main effectors of the changes in EI values. These results will help to improve control measures, prevent the spread of this pest, and revise the targeted quarantine areas.

  4. Generalized Extreme Value Distribution Models for the Assessment of Seasonal Wind Energy Potential of Debuncha, Cameroon

    Directory of Open Access Journals (Sweden)

    Nkongho Ayuketang Arreyndip

    2016-01-01

    Full Text Available The method of generalized extreme value family of distributions (Weibull, Gumbel, and Frechet is employed for the first time to assess the wind energy potential of Debuncha, South-West Cameroon, and to study the variation of energy over the seasons on this site. The 29-year (1983–2013 average daily wind speed data over Debuncha due to missing values in the years 1992 and 1994 is gotten from NASA satellite data through the RETScreen software tool provided by CANMET Canada. The data is partitioned into min-monthly, mean-monthly, and max-monthly data and fitted using maximum likelihood method to the two-parameter Weibull, Gumbel, and Frechet distributions for the purpose of determining the best fit to be used for assessing the wind energy potential on this site. The respective shape and scale parameters are estimated. By making use of the P values of the Kolmogorov-Smirnov statistic (K-S and the standard error (s.e analysis, the results show that the Frechet distribution best fits the min-monthly, mean-monthly, and max-monthly data compared to the Weibull and Gumbel distributions. Wind speed distributions and wind power densities of both the wet and dry seasons are compared. The results show that the wind power density of the wet season was higher than in the dry season. The wind speeds at this site seem quite low; maximum wind speeds are listed as between 3.1 and 4.2 m/s, which is below the cut-in wind speed of many modern turbines (6–10 m/s. However, we recommend the installation of low cut-in wind turbines like the Savonius or Aircon (10 KW for stand-alone low energy need.

  5. An economic evaluation of the potential for distributed energy in Australia

    International Nuclear Information System (INIS)

    Lilley, William E.; Reedman, Luke J.; Wagner, Liam D.; Alie, Colin F.; Szatow, Anthony R.

    2012-01-01

    We present here economic findings from a major study by Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) on the value of distributed energy technologies (DE; collectively demand management, energy efficiency and distributed generation) for reducing greenhouse gas emissions from Australia's energy sector (CSIRO, 2009). The study covered potential economic, environmental, technical, social, policy and regulatory impacts that could result from their wide scale adoption. Partial Equilibrium modeling of the stationary energy and transport sectors found that Australia could achieve a present value welfare gain of around $130 billion when operating under a 450 ppm carbon reduction trajectory through to 2050. Modeling also suggests that reduced volatility in the spot market could decrease average prices by up to 12% in 2030 and 65% in 2050 by using local resources to better cater for an evolving supply–demand imbalance. Further modeling suggests that even a small amount of distributed generation located within a distribution network has the potential to significantly alter electricity prices by changing the merit order of dispatch in an electricity spot market. Changes to the dispatch relative to a base case can have both positive and negative effects on network losses. - Highlights: ► Quantified impact of distributed generation (DG) on the Australian energy sector. ► Australia could achieve a welfare gain of around $130 billion through to 2050. ► Wholesale market modeling found that DG led to lower price levels and volatility. ► DG has impacts on the transmission system in terms of dispatch and system losses.

  6. Potential Cost-Effectiveness of Prenatal Distribution of Misoprostol for Prevention of Postpartum Hemorrhage in Uganda.

    Directory of Open Access Journals (Sweden)

    Solomon J Lubinga

    Full Text Available In settings where home birth rates are high, prenatal distribution of misoprostol has been advocated as a strategy to increase access to uterotonics during the third stage of labor to prevent postpartum hemorrhage (PPH. Our objective was to project the potential cost-effectiveness of this strategy in Uganda from both governmental (the relevant payer and modified societal perspectives.To compare prenatal misoprostol distribution to status quo (no misoprostol distribution, we developed a decision analytic model that tracked the delivery pathways of a cohort of pregnant women from the prenatal period, labor to delivery without complications or delivery with PPH, and successful treatment or death. Delivery pathway parameters were derived from the Uganda Demographic and Health Survey. Incidence of PPH, treatment efficacy, adverse event and case fatality rates, access to misoprostol, and health resource use and cost data were obtained from published literature and supplemented with expert opinion where necessary. We computed the expected incidence of PPH, mortality, disability adjusted life years (DALYs, costs and incremental cost effectiveness ratios (ICERs. We conducted univariate and probabilistic sensitivity analyses to examine robustness of our results. In the base-case analysis, misoprostol distribution lowered the expected incidence of PPH by 1.2% (95% credibility interval (CrI: 0.55%, 1.95%, mortality by 0.08% (95% CrI: 0.04%, 0.13% and DALYs by 0.02 (95% CrI: 0.01, 0.03.” and “ICERs were US$181 (95% CrI: 81, 443 per DALY averted from a governmental perspective, and US$64 (95% CrI: -84, 260 per DALY averted from a modified societal perspective [corrected].Prenatal distribution of misoprostol is potentially cost-effective in Uganda and should be considered for national-level scale up for prevention of PPH.

  7. Potential Distribution Predicted for Rhynchophorus ferrugineus in China under Different Climate Warming Scenarios.

    Science.gov (United States)

    Ge, Xuezhen; He, Shanyong; Wang, Tao; Yan, Wei; Zong, Shixiang

    2015-01-01

    As the primary pest of palm trees, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) has caused serious harm to palms since it first invaded China. The present study used CLIMEX 1.1 to predict the potential distribution of R. ferrugineus in China according to both current climate data (1981-2010) and future climate warming estimates based on simulated climate data for the 2020s (2011-2040) provided by the Tyndall Center for Climate Change Research (TYN SC 2.0). Additionally, the Ecoclimatic Index (EI) values calculated for different climatic conditions (current and future, as simulated by the B2 scenario) were compared. Areas with a suitable climate for R. ferrugineus distribution were located primarily in central China according to the current climate data, with the northern boundary of the distribution reaching to 40.1°N and including Tibet, north Sichuan, central Shaanxi, south Shanxi, and east Hebei. There was little difference in the potential distribution predicted by the four emission scenarios according to future climate warming estimates. The primary prediction under future climate warming models was that, compared with the current climate model, the number of highly favorable habitats would increase significantly and expand into northern China, whereas the number of both favorable and marginally favorable habitats would decrease. Contrast analysis of EI values suggested that climate change and the density of site distribution were the main effectors of the changes in EI values. These results will help to improve control measures, prevent the spread of this pest, and revise the targeted quarantine areas.

  8. Foraging on the potential energy surface: a swarm intelligence-based optimizer for molecular geometry.

    Science.gov (United States)

    Wehmeyer, Christoph; Falk von Rudorff, Guido; Wolf, Sebastian; Kabbe, Gabriel; Schärf, Daniel; Kühne, Thomas D; Sebastiani, Daniel

    2012-11-21

    We present a stochastic, swarm intelligence-based optimization algorithm for the prediction of global minima on potential energy surfaces of molecular cluster structures. Our optimization approach is a modification of the artificial bee colony (ABC) algorithm which is inspired by the foraging behavior of honey bees. We apply our modified ABC algorithm to the problem of global geometry optimization of molecular cluster structures and show its performance for clusters with 2-57 particles and different interatomic interaction potentials.

  9. Toward accurate prediction of potential energy surfaces and the spectral density of hydrogen bonded systems

    International Nuclear Information System (INIS)

    Rekik, Najeh

    2014-01-01

    Despite the considerable progress made in quantum theory and computational methods, detailed descriptions of the potential energy surfaces of hydrogen-bonded systems have not yet been achieved. In addition, the hydrogen bond (H-bond) itself is still so poorly understood at the fundamental level that it remains unclear exactly what geometry constitutes a “real” H-bond. Therefore, in order to investigate features essential for hydrogen bonded complexes, a simple, efficient, and general method for calculating matrix elements of vibrational operators capable of describing the stretching modes and the H-bond bridges of hydrogen-bonded systems is proposed. The derived matrix elements are simple and computationally easy to evaluate, which makes the method suitable for vibrational studies of multiple-well potentials. The method is illustrated by obtaining potential energy surfaces for a number of two-dimensional systems with repulsive potentials chosen to be in Gaussian form for the stretching mode and of the Morse-type for the H-bond bridge dynamics. The forms of potential energy surfaces of weak and strong hydrogen bonds are analyzed by varying the asymmetry of the Gaussian potential. Moreover, the choice and applicability of the selected potential for the stretching mode and comparison with other potentials used in the area of hydrogen bond research are discussed. The approach for the determination of spectral density has been constructed in the framework of the linear response theory for which spectral density is obtained by Fourier transform of the autocorrelation function of the dipole moment operator of the fast mode. The approach involves anharmonic coupling between the high frequency stretching vibration (double well potential) and low-frequency donor-acceptor stretching mode (Morse potential) as well as the electrical anharmonicity of the dipole moment operator of the fast mode. A direct relaxation mechanism is incorporated through a time decaying exponential

  10. Oxidation-state distribution of plutonium in surface and subsurface waters at Thule, northwest Greenland

    DEFF Research Database (Denmark)

    McMahon, C.A.; Vintró, L.L.; Mitchell, P.I.

    2000-01-01

    The speciation of plutonium in Arctic waters sampled on the northwest Greenland shelf in August 1997 is discussed in this paper. Specifically, we report the results of analyses carried out on seawater sampled (a) close to the Thule air base where, in 1968, a US military aircraft carrying four......(V, VI) (mean, 68 +/- 6%; n = 6), with little if any distinction apparent between surface and bottom waters. Further, the oxidation state distribution at stations close to the accident site is similar to that measured at Upernavik, remote from this site. It is also similar to the distribution observed...... in shelf waters at midlatitudes, suggesting that the underlying processes controlling plutonium speciation are insensitive to temperature over the range 0-25 degrees C. Measurements using tangential-flow ultrafiltration indicate that virtually all of the plutonium (including the fraction in a reduced...

  11. Distributed modeling of surface solar radiation based on aerosol optical depth and sunshine duration in China

    Science.gov (United States)

    Zeng, Xiaofan; Zhao, Na; Ma, Yue

    2018-02-01

    Surface solar radiation, as a major component of energy balance, is an important driving condition for nutrient and energy cycle in the Earth system. The spatial distribution of total solar radiation at 10 km×10 km resolution in China was simulated with Aerosol Optical Depth (AOD) data from remote sensing and observing sunshine hours data from ground meteorological stations based on Geographic Information System (GIS). The results showed that the solar radiation was significantly different in the country, and affected by both sunshine hours and AOD. Sunshine hours are higher in the Northwest than that in the Northeast, but solar radiation is lower because of the higher AOD, especially in autumn and winter. It was suggested that the calculation accuracy of solar radiation was limited if just based on sunshine hours, and AOD can be considered as the influencing factor which would help to improve the simulation accuracy of the total solar radiation and realize the solar radiation distributed simulation.

  12. Distribution of /sup 137/Cs in surface intertidal sediments from the Solway Firth

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D.G.; Miller, J.M.; Roberts, P.D. (Institute of Geological Sciences, Keyworth (UK))

    1984-05-01

    The distribution of /sup 137/Cs from the Sellafield (Windscale) nuclear fuel reprocessing plant has been examined in detail in the surface intertidal sediments of the inner Solway Firth by means of a hovercraft-borne radiometric survey. With the exception of a belt of relatively active sands to the south of Silloth, caesium distribution is generally consistent with that of fine-grained sediment such that the highest concentrations occur in mud flat and salt marsh sediments which are most extensive in sheltered coastal embayments. /sup 137/Cs activities in July 1980 were typically 2 to 30 pCi g/sup -1/ but locally exceeded 50 pCi g/sup -1/. These levels are considerably lower than those recorded in locations, such as the outer Solway and Ravenglass estuary, which are closer to the Sellafield outfall.

  13. Evaluation of two microwave surface distribution systems designed for substratum and agricultural soil disinfection

    International Nuclear Information System (INIS)

    Velázquez Martí, B.; Gracia López, C.

    2004-01-01

    Heat treatment by microwave for soil disinfection may represent an alternative to chemical treatments. One of the main problems in the design of microwave applicators for agricultural soil disinfection is to achieve a homogeneous surface energy distribution. This work has been carried out in order to evaluate two systems which can solve this problem: the first one is based on the use of a slotted waveguide and the other is based on overlapping the radiation of several magnetrons working simultaneously. Initially, the systems were modelled using an algorithm based on Maxwell equations in order to give a first overview of the system functioning. In a second step, the models were validated by comparison with thermal maps obtained empirically. As a consequence of this work we propose a redesign of the slotted waveguide system to improve the homogeneity of the temperature distribution over a large radiation area. The overlapping system gave adequate homogeneity for commercial purposes [es

  14. Distribution of Different Sized Ocular Surface Vessels in Diabetics and Normal Individuals.

    Science.gov (United States)

    Banaee, Touka; Pourreza, Hamidreza; Doosti, Hassan; Abrishami, Mojtaba; Ehsaei, Asieh; Basiry, Mohsen; Pourreza, Reza

    2017-01-01

    To compare the distribution of different sized vessels using digital photographs of the ocular surface of diabetic and normal individuals. In this cross-sectional study, red-free conjunctival photographs of diabetic and normal individuals, aged 30-60 years, were taken under defined conditions and analyzed using a Radon transform-based algorithm for vascular segmentation. The image areas occupied by vessels (AOV) of different diameters were calculated. The main outcome measure was the distribution curve of mean AOV of different sized vessels. Secondary outcome measures included total AOV and standard deviation (SD) of AOV of different sized vessels. Two hundred and sixty-eight diabetic patients and 297 normal (control) individuals were included, differing in age (45.50 ± 5.19 vs. 40.38 ± 6.19 years, P distribution curves of mean AOV differed between patients and controls (smaller AOV for larger vessels in patients; P distribution curve of vessels compared to controls. Presence of diabetes mellitus is associated with contraction of larger vessels in the conjunctiva. Smaller vessels dilate with diabetic retinopathy. These findings may be useful in the photographic screening of diabetes mellitus and retinopathy.

  15. Evaporation Flux Distribution of Drops on a Hydrophilic or Hydrophobic Flat Surface by Molecular Simulations.

    Science.gov (United States)

    Xie, Chiyu; Liu, Guangzhi; Wang, Moran

    2016-08-16

    The evaporation flux distribution of sessile drops is investigated by molecular dynamic simulations. Three evaporating modes are classified, including the diffusion dominant mode, the substrate heating mode, and the environment heating mode. Both hydrophilic and hydrophobic drop-substrate interactions are considered. To count the evaporation flux distribution, which is position dependent, we proposed an azimuthal-angle-based division method under the assumption of spherical crown shape of drops. The modeling results show that the edge evaporation, i.e., near the contact line, is enhanced for hydrophilic drops in all the three modes. The surface diffusion of liquid molecular absorbed on solid substrate for hydrophilic cases plays an important role as well as the space diffusion on the enhanced evaporation rate at the edge. For hydrophobic drops, the edge evaporation flux is higher for the substrate heating mode, but lower than elsewhere of the drop for the diffusion dominant mode; however, a nearly uniform distribution is found for the environment heating mode. The evidence shows that the temperature distribution inside drops plays a key role in the position-dependent evaporation flux.

  16. Surface-Wettability Patterning for Distributing High-Momentum Water Jets on Porous Polymeric Substrates.

    Science.gov (United States)

    Sen, Uddalok; Chatterjee, Souvick; Sinha Mahapatra, Pallab; Ganguly, Ranjan; Dodge, Richard; Yu, Lisha; Megaridis, Constantine M

    2018-02-07

    Liquid jet impingement on porous materials is particularly important in many applications of heat transfer, filtration, or in incontinence products. Generally, it is desired that the liquid not penetrate the substrate at or near the point of jet impact, but rather be distributed over a wider area before reaching the back side. A facile wettability-patterning technique is presented, whereby a water jet impinging orthogonally on a wettability-patterned nonwoven substrate is distributed on the top surface and through the porous matrix, and ultimately dispensed from prespecified points underneath the sample. A systematic approach is adopted to identify the optimum design that allows for a uniform distribution of the liquid on horizontally mounted substrates of ∼50 cm 2 area, with minimal or no spilling over the sample edges at jet flow rates exceeding 1 L/min. The effect of the location of jet impingement on liquid distribution is also studied, and the design is observed to perform well even under offset jet impact conditions.

  17. System architecture and operational analysis of medium displacement unmanned surface vehicle sea hunter as a surface warfare component of distributed lethality

    Science.gov (United States)

    2017-06-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release. Distribution is unlimited. SYSTEM ARCHITECTURE ...TITLE AND SUBTITLE SYSTEM ARCHITECTURE AND OPERATIONAL ANALYSIS OF MEDIUM DISPLACEMENT UNMANNED SURFACE VEHICLE SEA HUNTER AS A SURFACE WARFARE...traceability, requirements and capabilities while determining the architecture framework in accordance with the Department of Defense Architectural

  18. Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

    Science.gov (United States)

    Zhan, Hanyu; Voelz, David G.

    2016-12-01

    The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.

  19. Surface-distributed low-frequency asynchronous stimulation delays fatigue of stimulated muscles.

    Science.gov (United States)

    Maneski, Lana Z Popović; Malešević, Nebojša M; Savić, Andrej M; Keller, Thierry; Popović, Dejan B

    2013-12-01

    One important reason why functional electrical stimulation (FES) has not gained widespread clinical use is the limitation imposed by rapid muscle fatigue due to non-physiological activation of the stimulated muscles. We aimed to show that asynchronous low-pulse-rate (LPR) electrical stimulation applied by multipad surface electrodes greatly postpones the occurrence of muscle fatigue compared with conventional stimulation (high pulse rate, HPR). We compared the produced force vs. time of the forearm muscles responsible for finger flexion in 2 stimulation protocols, LPR (fL = 10 Hz) and HPR (fH = 40 Hz). Surface-distributed low-frequency asynchronous stimulation (sDLFAS) doubles the time interval before the onset of fatigue (104 ± 80%) compared with conventional synchronous stimulation. Combining the performance of multipad electrodes (increased selectivity and facilitated positioning) with sDLFAS (decreased fatigue) can improve many FES applications in both the lower and upper extremities. Copyright © 2013 Wiley Periodicals, Inc.

  20. Pyrometer for measurement of surface temperature distribution on a rotating turbine blade.

    Science.gov (United States)

    Buchele, D. R.; Lesco, D. J.

    1972-01-01

    A conceptual optical method and some test results are presented for measuring the surface temperature distribution on one of the rotating turbine blades with a surface resolution of 0.05 cm spot diameter at a tip speed of 400 m/sec. The blade is scanned line-by-line by a fixed optical system. During each line-scan, the detector analog output signal is converted to 200 consecutive digital values that are temporarily stored in a high-speed buffer memory and then transferred at a slower rate to a computer for processing. The signal-to-noise ratio of the silicon avalanche detector is large enough to obtain an accuracy of 1% at 1050 K blade temperature. By averaging 25 scans of the same line the same accuracy can be obtained at 900 K.

  1. Predicting potential global distributions of two Miscanthus grasses: implications for horticulture, biofuel production, and biological invasions.

    Science.gov (United States)

    Hager, Heather A; Sinasac, Sarah E; Gedalof, Ze'ev; Newman, Jonathan A

    2014-01-01

    In many regions, large proportions of the naturalized and invasive non-native floras were originally introduced deliberately by humans. Pest risk assessments are now used in many jurisdictions to regulate the importation of species and usually include an estimation of the potential distribution in the import area. Two species of Asian grass (Miscanthus sacchariflorus and M. sinensis) that were originally introduced to North America as ornamental plants have since escaped cultivation. These species and their hybrid offspring are now receiving attention for large-scale production as biofuel crops in North America and elsewhere. We evaluated their potential global climate suitability for cultivation and potential invasion using the niche model CLIMEX and evaluated the models' sensitivity to the parameter values. We then compared the sensitivity of projections of future climatically suitable area under two climate models and two emissions scenarios. The models indicate that the species have been introduced to most of the potential global climatically suitable areas in the northern but not the southern hemisphere. The more narrowly distributed species (M. sacchariflorus) is more sensitive to changes in model parameters, which could have implications for modelling species of conservation concern. Climate projections indicate likely contractions in potential range in the south, but expansions in the north, particularly in introduced areas where biomass production trials are under way. Climate sensitivity analysis shows that projections differ more between the selected climate change models than between the selected emissions scenarios. Local-scale assessments are required to overlay suitable habitat with climate projections to estimate areas of cultivation potential and invasion risk.

  2. Predicting potential global distributions of two Miscanthus grasses: implications for horticulture, biofuel production, and biological invasions.

    Directory of Open Access Journals (Sweden)

    Heather A Hager

    Full Text Available In many regions, large proportions of the naturalized and invasive non-native floras were originally introduced deliberately by humans. Pest risk assessments are now used in many jurisdictions to regulate the importation of species and usually include an estimation of the potential distribution in the import area. Two species of Asian grass (Miscanthus sacchariflorus and M. sinensis that were originally introduced to North America as ornamental plants have since escaped cultivation. These species and their hybrid offspring are now receiving attention for large-scale production as biofuel crops in North America and elsewhere. We evaluated their potential global climate suitability for cultivation and potential invasion using the niche model CLIMEX and evaluated the models' sensitivity to the parameter values. We then compared the sensitivity of projections of future climatically suitable area under two climate models and two emissions scenarios. The models indicate that the species have been introduced to most of the potential global climatically suitable areas in the northern but not the southern hemisphere. The more narrowly distributed species (M. sacchariflorus is more sensitive to changes in model parameters, which could have implications for modelling species of conservation concern. Climate projections indicate likely contractions in potential range in the south, but expansions in the north, particularly in introduced areas where biomass production trials are under way. Climate sensitivity analysis shows that projections differ more between the selected climate change models than between the selected emissions scenarios. Local-scale assessments are required to overlay suitable habitat with climate projections to estimate areas of cultivation potential and invasion risk.

  3. Potential and Kinetic Electron Emissions from HOPG Surface Irradiated by Highly Charged Xenon and Neon Ions

    International Nuclear Information System (INIS)

    Yu-Yu, Wang; Yong-Tao, Zhao; Jian-Rong, Sun; De-Hui, Li; Jin-Yu, Li; Ping-Zhi, Wang; Guo-Qing, Xiao; Abdul, Qayyum

    2011-01-01

    Highly charged 129 Xe q+ (q = 10−30) and 40 Ne q+ (q = 4−8) ion-induced secondary electron emissions on the surface of highly oriented pyrolytic graphite (HOPG) are reported. The total secondary electron yield is measured as a function of the potential energy of incident ions. The experimental data are used to separate contributions of kinetic and potential electron yields. Our results show that about 4.5% and 13.2% of ion's potential energies are consumed in potential electron emission due to different Xe q+ -HOPG and Ne q+ -HOPG combinations. A simple formula is introduced to estimate the fraction of ion's potential energy for potential electron emission. (atomic and molecular physics)

  4. Surface Mass Balance Distributions: Downscaling of Coarse Climates to drive Ice Sheet Models realistically

    Science.gov (United States)

    Rodehacke, Christian; Mottram, Ruth; Langen, Peter; Madsen, Marianne; Yang, Shuting; Boberg, Fredrik; Christensen, Jens

    2017-04-01

    The surface mass balance (SMB) is the most import boundary conditions for the state of glaciers and ice sheets. Hence its representation in numerical model simulations is of highest interest for glacier, ice cap and ice sheet modeling efforts. While descent SMB distributions of the current climate could be interfered with the help of various observation techniques and platforms, its construction for older past and future climates relies on input from spatially coarse resolved global climate models or reconstructions. These coarse SMB estimates with a footprint in the order of 100 km could hardly resolve the marginal ablations zones where the Greenland ice sheets, for instance, loses snow and ice. We present a downscaling method that is based on the physical calculation of the surface mass and energy balance. By the consequent application of universal and computationally cheap parameterizations we get an astonishing good representation of the SMB distribution including its marginal ablation zone. However the method has its limitations; for example wrong accumulation rates due to an insufficient precipitation field leaves its imprint on the SMB distribution. Also the still not satisfactory description of the bare ice albedo, in particular, in parts of Greenland is a challenge. We inspect our Greenland SMB fields' for various forcings and compare them with some widely used reference fields in the community to highlight the weakness and strength of our approach. We use the ERA-Interim reanalyzes period starting in 1979 directly as well as dynamically downscaled by our regional climate model HIRHAM (5 km resolution). Also SMB distributions obtained from the climate model EC-Earth with a resolution of T159 (approx. 125 km resolution in Greenland) are used either directly or downscaled with our regional climate model HIRHAM. Model-based End-of-the-century SMB estimates give an outlook of the future.

  5. Assessing the potential impacts of a changing climate on the distribution of a rabies virus vector.

    Directory of Open Access Journals (Sweden)

    Mark A Hayes

    Full Text Available Common vampire bats (Desmodus rotundus occur throughout much of South America to northern México. Vampire bats have not been documented in recent history in the United States, but have been documented within about 50 km of the U.S. state of Texas. Vampire bats feed regularly on the blood of mammals and can transmit rabies virus to native species and livestock, causing impacts on the health of prey. Thus cattle producers, wildlife management agencies, and other stakeholders have expressed concerns about whether vampire bats might spread into the southern United States. On the other hand, concerns about vampire-borne rabies can also result in wanton destruction at bat roosts in areas occupied by vampire bats, but also in areas not known to be occupied by this species. This can in turn negatively affect some bat roosts, populations, and species that are of conservation concern, including vampire bats. To better understand the current and possible future distribution of vampire bats in North America and help mitigate future cattle management problems, we used 7,094 vampire bat occurrence records from North America and species distribution modeling (SDM to map the potential distribution of vampire bats in North America under current and future climate change scenarios. We analysed and mapped the potential distribution of this species using 5 approaches to species distribution modeling: logistic regression, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy. We then projected these models into 17 "worst-case" future climate scenarios for year 2070 to generate hypotheses about how the vampire bat distribution in North America might change in the future. Of the variables used in this analysis, minimum temperature of the coldest month had the highest variable importance using all 5 SDM approaches. These results suggest two potential near-future routes of vampire bat dispersal into the U.S., one via

  6. Study of surface potential contamination in radioisotope and radiopharmaceutical production facilities and alternative solutions

    International Nuclear Information System (INIS)

    Suhaedi Muhammad; Rimin Sumantri; Farida Tusafariah; Djarwanti Rahayu Pipin Soedjarwo

    2013-01-01

    Radioisotope and radiopharmaceutical production facilities that exist in their operations around the world in the form of radiological impacts of radiation exposure, contamination of surface and air contamination. Given the number of existing open source in radioisotope and radiopharmaceutical production facility, then the possibility of surface contamination in the work area is quite high. For that to protect the safety and health of both workers, the public and the environment, then the licensee must conduct an inventory of some of the potential that could result in contamination of surfaces in radioisotope and radiopharmaceutical production facilities. Several potential to cause surface contamination in radioisotope and radiopharmaceutical production facilities consist of loss of resources, the VAC system disorders, impaired production facilities, limited resources and lack of work discipline and radioactive waste handling activities. From the study of some potential, there are several alternative solutions that can be implemented by the licensee to address the contamination of the surface so as not to cause adverse radiological impacts for both radiation workers, the public or the environment. (author)

  7. Minimal configuration of body surface potential mapping for discrimination of left versus right dominant frequencies during atrial fibrillation.

    Science.gov (United States)

    Rodrigo, M; Climent, A M; Liberos, A; Fernández-Aviles, F; Atienza, F; Guillem, M S; Berenfeld, O

    2017-08-01

    Ablation of drivers maintaining atrial fibrillation (AF) has been demonstrated as an effective therapy. Drivers in the form of rapidly activated atrial regions can be noninvasively localized to either left or right atria (LA, RA) with body surface potential mapping (BSPM) systems. This study quantifies the accuracy of dominant frequency (DF) measurements from reduced-leads BSPM systems and assesses the minimal configuration required for ablation guidance. Nine uniformly distributed lead sets of eight to 66 electrodes were evaluated. BSPM signals were registered simultaneously with intracardiac electrocardiograms (EGMs) in 16 AF patients. DF activity was analyzed on the surface potentials for the nine leads configurations, and the noninvasive measures were compared with the EGM recordings. Surface DF measurements presented similar values than panoramic invasive EGM recordings, showing the highest DF regions in corresponding locations. The noninvasive DFs measures had a high correlation with the invasive discrete recordings; they presented a deviation of 0.8 for leads configurations with 12 or more electrodes. Reduced-leads BSPM systems enable noninvasive discrimination between LA versus RA DFs with similar results as higher-resolution 66-leads system. Our findings demonstrate the possible incorporation of simplified BSPM systems into clinical planning procedures for AF ablation. © 2017 Wiley Periodicals, Inc.

  8. [Treatment of burn surfaces by proteinases: mathematical description of an enzyme distribution].

    Science.gov (United States)

    Khalili, A S; Domogatskiĭ, S P; Blizniukov, O P; Ruuge, E K

    2003-01-01

    The process of penetration of a proteolytic enzyme applied to the surface of burn wound into the depth of necrotic tissue was considered. The model approximation describes three factors by a series of mathematical equations: inward-directed enzyme diffusion, counter-flow filtration of interstitial fluid (exudates), and irreversible inactivation of the enzyme by specific inhibitors present in exudates. According to the model, a quasi-stationary distribution of enzymatic activity through the thickness of the necrotic layer is achieved within 3 h and persists as long as the enzyme concentration on the wound surface is constant. The enzyme activity diminishes linearly from the wound surface to the mid-part of the necrotic layer. No enzyme activity is retained in the inner mid-part of the necrotic layer completely protected by the prevalent inhibitor. The ratio of enzyme concentration on the wound surface to inhibitor concentration in the interstitial fluid is the same as the ratio of the depth of active enzyme area to the depth of the inhibitor-protected area through the necrotic layer. The dynamics of accumulation of the active enzyme in the necrotic zone and the rate of enzyme inactivation in the wound by inhibitors were described by formulas applicable for practical purposes.

  9. Distribution and sources of n-alkanes in surface sediments of Taihu Lake, China

    Directory of Open Access Journals (Sweden)

    Yu Yunlong

    2016-03-01

    Full Text Available The last study on n-alkanes in surface sediments of Taihu Lake was in 2000, only 13 surface sediment samples were analysed, in order to have a comprehensive and up-to-date understanding of n-alkanes in the surface sediments of Taihu Lake, 41 surface sediment samples were analyzed by GC-MS. C10 to C37 were detected, the total concentrations of n-alkanes ranged from 2109 ng g−1 to 9096 ng g−1 (dry weight. There was strong odd carbon predominance in long chain n-alkanes and even carbon predominance in short chain n-alkanes. When this finding was combined with the analysis results of wax n-alkanes (WaxCn, carbon preference index (CPI, unresolved complex mixture (UCM, hopanes and steranes, it was considered that the long chain n-alkanes were mainly from terrigenous higher plants, and that the short chain n-alkanes mainly originated from bacteria and algae in the lake, compared with previous studies, there were no obvious anthropogenic petrogenic inputs. Terrestrial and aquatic hydrocarbons ratio (TAR and C21−/C25+ indicated that terrigenous input was higher than aquatic sources and the nearshore n-alkanes were mainly from land-derived sources. Moreover, the distribution of short chain n-alkanes presented a relatively uniform pattern, while the long chain n-alkanes presented a trend that concentrations dropped from nearshore places to the middle of lake.

  10. Surface-deposition and distribution of the radon-decay products indoors

    International Nuclear Information System (INIS)

    Espinosa, G.; Tommasino, L.

    2015-01-01

    The exposure to radon-decay products is of great concern both in dwellings and workplaces. The model to estimate the lung dose refers to the deposition mechanisms and particle sizes. Unfortunately, most of the dose data available are based on the measurement of radon concentration and the concentration of radon decay products. These combined measurements are widely used in spite of the fact that accurate dose assessments require information on the particle deposition mechanisms and the spatial distribution of radon decay products indoors. Most of the airborne particles and/or radon decay products are deposited onto indoor surfaces, which deposition makes the radon decay products unavailable for inhalation. These deposition processes, if properly known, could be successfully exploited to reduce the exposure to radon decay products. In spite of the importance of the surface deposition of the radon decay products, both for the correct evaluation of the dose and for reducing the exposure; little or no efforts have been made to investigate these deposition processes. Recently, two parallel investigations have been carried out in Rome and at Universidad Nacional Autónoma de México (UNAM) in Mexico City respectively, which address the issue of the surface-deposited radon decay products. Even though these investigations have been carried independently, they complement one another. It is with these considerations in mind that it was decided to report both investigations in the same paper. - Highlights: • Distribution of Radon and Thoron decay indoor products. • Indoor radon measurements complexity. • Short and long term measurements of surface deposit of Radon and Thoron decay products. • Microclimate controlled conditions room. • Nuclear Tracks Detectors

  11. Predicting the spatial distribution of Biomphalaria straminea, a potential intermediate host for Schistosoma mansoni, in China

    Directory of Open Access Journals (Sweden)

    Mohamed R. Habib

    2016-11-01

    Full Text Available Schistosomiasis is one of the most prevalent parasitic diseases impacting human health in the tropics and sub-tropics. The geographic distribution of Schistosoma mansoni, the most widespread species, includes areas in Africa, the Middle East, South America and the Caribbean. Snails of the genus Biomphalaria act as intermediate host for S. mansoni. Biomphalaria straminea is not indigenous in China but was accidentally introduced to Hong Kong from South America and has spread to other habitats in the southern parts of the country. This species is known for its great dispersal capacity that highlights the importance of the snail as a potential host for S. mansoni in China. In this connection, although no such infection has been recorded in the field so far, the continuous expansion of China’s projects in endemic areas of Africa and import of the infection via returning workers or visitors deserve attention. The purpose of this study was to map and predict the spatial distribution of B. straminea in China. Snail occurrence data were assembled and investigated using MaxEnt software, along with climatic and environmental variables to produce a predictive risk map. Of the environmental variables tested, the precipitation of warmest quarter was the most contribution factor for snail’s spatial distribution. Risk areas were found in southeastern China and it is expected that they will guide policies and control programmes to potential areas area of snail abundance and used for spatial targeting of control interventions for this invasive species.

  12. Distribution and habitat specificity of potentially-toxic Microcystis across climate, land and water use gradients.

    Directory of Open Access Journals (Sweden)

    Sophi eMarmen

    2016-03-01

    Full Text Available Toxic cyanobacterial blooms are a growing threat to freshwater bodies worldwide. In order for a toxic bloom to occur, a population of cells with the genetic capacity to produce toxins must be present together with the appropriate environmental conditions. In this study, we investigated the distribution patterns and phylogeny of potentially-toxic Microcystis (indicated by the presence and/or phylogeny of the mcyD and mcyA genes. Samples were collected from the water column of almost sixty water bodies across widely differing gradients of environmental conditions and land use in Israel. Potentially toxic populations were common but not ubiquitous, detected in ~65% of the studied sites. Local environmental factors, including phosphorus and ammonia concentrations and pH, as well as regional conditions such as the distance from built areas and nature reserves, were correlated with the distribution of the mcyD gene. A specific phylogenetic clade of Microcystis, defined using the sequence of the mcyA gene, was preferentially associated with aquaculture facilities but not irrigation reservoirs. Our results reveal important environmental, geospatial, and land use parameters affecting the geographic distribution of toxinogenic Microcystis, suggesting non-random dispersal of these globally abundant toxic cyanobacteria.

  13. Surface ozone in China: present-day distribution and long-term changes

    Science.gov (United States)

    Xu, X.; Lin, W.; Xu, W.

    2017-12-01

    Reliable knowledge of spatio-temporal variations of surface ozone is highly needed to assess the impacts of ozone on human health, ecosystem and climate. Although regional distributions and trends of surface ozone in European and North American countries have been well characterized, little is known about the variability of surface ozone in many other countries, including China, where emissions of ozone precursors have been changing rapidly in recent decades. Here we present the first comprehensive description of present-day (2013-2017) distribution and long-term changes of surface ozone in mainland China. Recent ozone measurements from China's air quality monitoring network (AQMN) are analyzed to show present-day distributions of a few ozone exposure metrics for urban environment. Long-term measurements of ozone at six background sites, a rural site and an urban are used to study the trends of ozone in background, rural and urban air, respectively. The average levels of ozone at the AQMN sites (mainly urban) are close to those found at many European and North American sites. However, ozone at most of the sites shows very large diurnal and seasonal variations so that ozone nonattainment can occur in many cities, particularly those in the North China Plain (NCP), the south of Northeast China (NEC), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), and the Sichuan Basin-Chongqing region (SCB). In all these regions, particularly in the NCP, the maximum daily 8-h average (MDA8) ozone concentration can significantly exceed the national limit (75 ppb). High annual sum of ozone means over 35 ppb (SOMO35) exist mainly in the NCP, NEC and YRD, with regional averages over 4000 ppb·d. Surface ozone has significantly increased at Waliguan (a baseline site in western China) and Shangdianzi (a background site in the NCP), and decreased in winter and spring at Longfengshan (a background site in Northeast China). No clear trend can be derived from long-term measurements

  14. Lunar Surface Electric Potential Changes Associated with Traversals through the Earth's Foreshock

    Science.gov (United States)

    Collier, Michael R.; Hills, H. Kent; Stubbs, Timothy J.; Halekas, Jasper S.; Delory, Gregory T.; Espley, Jared; Farrell, William M.; Freeman, John W.; Vondrak, Richard

    2011-01-01

    We report an analysis of one year of Suprathermal Ion Detector Experiment (SIDE) Total Ion Detector (TID) resonance events observed between January 1972 and January 1973. The study includes only those events during which upstream solar wind conditions were readily available. The analysis shows that these events are associated with lunar traversals through the dawn flank of the terrestrial magnetospheric bow shock. We propose that the events result from an increase in lunar surface electric potential effected by secondary electron emission due to primary electrons in the Earth's foreshock region (although primary ions may play a role as well). This work establishes (1) the lunar surface potential changes as the Moon moves through the terrestrial bow shock, (2) the lunar surface achieves potentials in the upstream foreshock region that differ from those in the downstream magnetosheath region, (3) these differences can be explained by the presence of energetic electron beams in the upstream foreshock region and (4) if this explanation is correct, the location of the Moon with respect to the terrestrial bow shock influences lunar surface potential.

  15. Ab initio ground state phenylacetylene-argon intermolecular potential energy surface and rovibrational spectrum

    DEFF Research Database (Denmark)

    Cybulski, Hubert; Fernandez, Berta; Henriksen, Christian

    2012-01-01

    We evaluate the phenylacetylene-argon intermolecular potential energy surface by fitting a representative number of ab initio interaction energies to an analytic function. These energies are calculated at a grid of intermolecular geometries, using the CCSD(T) method and the aug-cc-pVDZ basis set ...... Institute of Physics. [http://dx.doi.org/10.1063/1.4742153]...

  16. Dipyridamole Body Surface Potential Mapping: Noninvasive Differentiation of Syndrome X from Coronary Artery Disease

    Czech Academy of Sciences Publication Activity Database

    Boudík, F.; Anger, Z.; Aschermann, M.; Vojáček, J.; Tomečková, Marie

    2002-01-01

    Roč. 35, č. 3 (2002), s. 181-191 ISSN 0022-0736 R&D Projects: GA MZd IZ4038 Keywords : body surface potential mapping * dipyridamole * coronary artery disease * syndrome X Subject RIV: BD - Theory of Information Impact factor: 0.599, year: 2002

  17. Nanoscale surface potential imaging of the photocatalytic TiO2 films on aluminum

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Dirscherl, Kai; Canulescu, Stela

    2013-01-01

    The change in the surface potential of TiO2 coatings upon UV-illumination was investigated on the nanoscale using Scanning Kelvin Probe Force microscopy and on the micro-scale using photo-electrochemical measurements. A good correlation between the two techniques was obtained. The changes in the ...

  18. A new analytical potential energy surface for the adsorption systemk CO/Cu(100)

    NARCIS (Netherlands)

    Marquardt, R.; Cuvelier, F.; Olsen, R.A.; Baerends, E.J.; Tremblay, J.C.; Saalfrank, P.

    2010-01-01

    Electronic structure data and analytical representations of the potential energy surface for the adsorption of carbon monoxide on a crystalline copper Cu(100) substrate are reviewed. It is found that a previously published and widely used analytical hypersurface for this process [J. C. Tully, M.

  19. Ab initio potential-energy surface and rovibrational states of the HCN-HCl complex

    NARCIS (Netherlands)

    Avoird, A. van der; Pedersen, T.B.; Dhont, G.S.F.; Fernandez, B.; Koch, H.

    2006-01-01

    A four-dimensional intermolecular potential-energy surface has been calculated for the HCN-HCl complex, with the use of the coupled cluster method with single and double excitations and noniterative inclusion of triples. Data for more than 13 000 geometries were represented by an angular expansion

  20. Impact of organic overlayers on a-Si:H/c-Si surface potential

    KAUST Repository

    Seif, Johannes P.

    2017-04-11

    Bilayers of intrinsic and doped hydrogenated amorphous silicon, deposited on crystalline silicon (c-Si) surfaces, simultaneously provide contact passivation and carrier collection in silicon heterojunction solar cells. Recently, we have shown that the presence of overlaying transparent conductive oxides can significantly affect the c-Si surface potential induced by these amorphous silicon stacks. Specifically, deposition on the hole-collecting bilayers can result in an undesired weakening of contact passivation, thereby lowering the achievable fill factor in a finished device. We test here a variety of organic semiconductors of different doping levels, overlaying hydrogenated amorphous silicon layers and silicon-based hole collectors, to mitigate this effect. We find that these materials enhance the c-Si surface potential, leading to increased implied fill factors. This opens opportunities for improved device performance.

  1. Occurrence survey and spatial distribution of perfluoroalkyl and polyfluoroalkyl surfactants in groundwater, surface water, and sediments from tropical environments.

    Science.gov (United States)

    Munoz, Gabriel; Labadie, Pierre; Botta, Fabrizio; Lestremau, François; Lopez, Benjamin; Geneste, Emmanuel; Pardon, Patrick; Dévier, Marie-Hélène; Budzinski, Hélène

    2017-12-31

    The occurrence and spatial distribution of 22 selected perfluoroalkyl and polyfluoroalkyl substances (PFASs) in surface water (n=75), groundwater (n=80) and surficial sediment (n=15) were investigated for the first time in the tropical areas constituted by the French Overseas Territories (French Guiana, Guadeloupe, Martinique, Mayotte and Reunion). Descriptive statistics and correlations between PFASs were evaluated through the use of specific statistical treatments to handle left-censored data ("non-detects"). PFASs were ubiquitous in these samples and detection frequencies as high as 79% for perfluorooctane sulfonate (PFOS) and 65% for perfluorooctanoate (PFOA) were reported in surface waters. ∑PFASs was in the rangewaters and PFAS composition profiles in surface water, while shorter-chain compounds prevailed in groundwater, highlighting their higher transfer potential through infiltration processes and the possible influence of precursors. Elevated levels of 6:2 fluorotelomer sulfonate (6:2 FTSA) and short-chain perfluoroalkyl carboxylates were found in groundwater near several industrial facilities such as oil refineries or electricity power plants. This may be related to the existence of firefighting operations involving the use of aqueous film forming foams (AFFFs) that contain precursors to such compounds. These findings would also tend to confirm recent trends regarding the increasing proportion of C 4 - or C 6 -based perfluoroalkyl acids, their precursors, or even shorter-chain congeners at PFAS hot spots. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Mapping the ecological dimensions and potential distributions of endangered relic shrubs in western Ordos biodiversity center.

    Science.gov (United States)

    Zhu, Geng-Ping; Li, Hui-Qi; Zhao, Li; Man, Liang; Liu, Qiang

    2016-05-20

    Potential distributions of endemic relic shrubs in western Ordos were poorly mapped, which hindered our implementation of proper conservation. Here we investigated the applicability of ecological niche modeling for endangered relic shrubs to detect areas of priority for biodiversity conservation and analyze differences in ecological niche spaces used by relic shrubs. We applied ordination and niche modeling techniques to assess main environmental drivers of five endemic relic shrubs in western Ordos, namely, Ammopiptanthus mongolicus, Amygdalus mongolica, Helianthemum songaricum, Potaninia mongolica, and Tetraena mongolica. We calculated niche overlap metrics in gridded environmental spaces and compared geographical projections of ecological niches to determine similarities and differences of niches occupied by relic shrubs. All studied taxa presented different responses to environmental factors, which resulted in a unique combination of niche conditions. Precipitation availability and soil quality characteristics play important roles in the distributions of most shrubs. Each relic shrub is constrained by a unique set of environmental conditions, the distribution of one species cannot be implied by the distribution of another, highlighting the inadequacy of one-fits-all type of conservation measure. Our stacked habitat suitability maps revealed regions around Yellow River, which are highly suitable for most species, thereby providing high conservation value.

  3. Potential dependence of surface crystal structure of iron passive films in borate buffer solution

    International Nuclear Information System (INIS)

    Deng, Huihua; Nanjo, Hiroshi; Qian, Pu; Santosa, Arifin; Ishikawa, Ikuo; Kurata, Yoshiaki

    2007-01-01

    The effect of passivation potential on surface crystal structure, apparent thickness and passivity of oxide films formed on pure iron prepared by plasma sputter deposition was investigated. The crystallinity was improved with passivation potential and the width of atomically flat terraces was expanded to 6 nm when passivating at 750 mV for 15 min, as observed by ex situ scanning tunneling microscopy (STM) after aging in air (<30% RH). Apparent thickness and passivity are linearly dependent on passivation potential. The former weakly depends on passivation duration, the latter strongly depends on passivation duration. This is well explained by the correlation between crystal structure and passivity

  4. Refined potentials for rare gas atom adsorption on rare gas and alkali-halide surfaces

    Science.gov (United States)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1985-01-01

    The utilization of models of interatomic potential for physical interaction to estimate the long range attractive potential for rare gases and ions is discussed. The long range attractive force is calculated in terms of the atomic dispersion properties. A data base of atomic dispersion parameters for rare gas atoms, alkali ion, and halogen ions is applied to the study of the repulsive core; the procedure for evaluating the repulsive core of ion interactions is described. The interaction of rare gas atoms on ideal rare gas solid and alkali-halide surfaces is analyzed; zero coverage absorption potentials are derived.

  5. Spatial distribution and pollution assessment of heavy metals in the surface sediments of the Bohai and Yellow Seas.

    Science.gov (United States)

    Xu, Xiaoda; Cao, Zhimin; Zhang, Zhixun; Li, Rihui; Hu, Bangqi

    2016-09-15

    A total of 141 surface sediments were collected and analyzed for their geochemistry, total organic carbon, and grain size to assess the heavy metal pollution in the Bohai and Yellow Seas. The enrichment factor (EF) and geoaccumulation index (Igeo) of Cu, Pb, Zn, Cr, Cd, Ni, As, and Hg were calculated to assess anthropogenic contamination, and the results suggest that moderate Pb, Cd, and As contamination occurs in the study area. Sediment quality guidelines were applied to assess the adverse biological effects of these metals. The spatial distribution of the mean Effects Range-Median quotient for the vast majority of the study area is between 0.1 and 0.5, indicating low impact and potential negative biological effects. Multivariate analysis indicates that Cu, Pb, Zn, Cr, and Ni resulted primarily from lithogenic sources, whereas As, Cd, and Hg were mainly attributed to anthropogenic sources. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Mapping the Distribution of Potential Land Drought in Batam Island Using the Integration of Remote Sensing and Geographic Information Systems (GIS)

    Science.gov (United States)

    Lubis, M. Z.; Taki, H. M.; Anurogo, W.; Pamungkas, D. S.; Wicaksono, P.; Aprilliyanti, T.

    2017-12-01

    Potential land drought mapping on Batam is needed to determine the distribution of areas that are very potential to the physical drought of the land. It is because the drought is always threatening on the long dry season. This research integrates remote sensing science with Geographic Information System (GIS). This research aims to map the distribution of land drought potential in Batam Island. The parameters used in this research are land use, Land Surface Temperature (LST), Potential dryness of land on the Batam island. The resulting map indicates the existence of five potential drought classes on the island of Batam. The area of very low drought potential is 2629.45 ha, mostly located in the Sungai Beduk sub-district. High drought potential with an area of 7081.39 ha is located in Sekupang sub-district. The distribution of very high land drought potential is in Batam city and Nongsa sub-district with area of 15600.12 ha. The coefficient of determination (R 2) is 0.6279. This indicates a strong positive relationship between field LST and modelled LST.

  7. Evaluation of surface charge density and surface potential by electrophoretic mobility for solid lipid nanoparticles and human brain-microvascular endothelial cells.

    Science.gov (United States)

    Kuo, Yung-Chih; Chen, I-Chun

    2007-09-27

    Electrophoretic mobility, zeta potential, surface charge density, and surface potential of cacao butter-based solid lipid nanoparticles (SLN) and human brain-microvascular endothelial cells (HBMEC) were analyzed in this study. Electrophoretic mobility and zeta potential were determined experimentally. Surface charge density and surface potential were evaluated theoretically via incorporation of ion condensation theory with the relationship between surface charge density and surface potential. The results revealed that the lower the pH value, the weaker the electrostatic properties of the negatively charged SLN and HBMEC. A higher content of cacao butter or a slower stirring rate yielded a larger SLN and stronger surface electricity. On the contrary, storage led to instability of SLN suspension and weaker electrical behavior because of hydrolysis of ionogenic groups on the particle surfaces. Also, high H+ concentration resulted in excess adsorption of H+ onto HBMEC, rendering charge reversal and cell death. The largest normalized discrepancy between surface potential and zeta potential occurred at pH = 7. For a fixed biocolloidal species, the discrepancy was nearly invariant at high pH value. However, the discrepancy followed the order of electrical intensity for HBMEC system at low pH value because mammalian cells were sensitive to H+. The present study provided a practical method to obtain surface charge properties by capillary electrophoresis.

  8. Potential Distribution of Chagas Disease Vectors (Hemiptera, Reduviidae, Triatominae) in Colombia, Based on Ecological Niche Modeling.

    Science.gov (United States)

    Parra-Henao, Gabriel; Suárez-Escudero, Laura C; González-Caro, Sebastián

    2016-01-01

    Ecological niche modeling of Triatominae bugs allow us to establish the local risk of transmission of the parasite Trypanosoma cruzi, which causes Chagas disease. This information could help to guide health authority recommendations on infection monitoring, prevention, and control. In this study, we estimated the geographic distribution of triatomine species in Colombia and identified the relationship between landscape structure and climatic factors influencing their occurrence. A total of 2451 records of 4 triatomine species ( Panstrongylus geniculatus , Rhodnius pallescens , R. prolixus , and Triatoma maculata ) were analyzed. The variables that provided more information to explain the ecologic niche of these vectors were related to precipitation, altitude, and temperature. We found that the species with the broadest potential geographic distribution were P. geniculatus , R. pallescens , and R. prolixus . In general, the models predicted the highest occurrence probability of these vectors in the eastern slope of the Eastern Cordillera, the southern region of the Magdalena valley, and the Sierra Nevada of Santa Marta.

  9. Potential Distribution of Chagas Disease Vectors (Hemiptera, Reduviidae, Triatominae) in Colombia, Based on Ecological Niche Modeling

    Science.gov (United States)

    Suárez-Escudero, Laura C.; González-Caro, Sebastián

    2016-01-01

    Ecological niche modeling of Triatominae bugs allow us to establish the local risk of transmission of the parasite Trypanosoma cruzi, which causes Chagas disease. This information could help to guide health authority recommendations on infection monitoring, prevention, and control. In this study, we estimated the geographic distribution of triatomine species in Colombia and identified the relationship between landscape structure and climatic factors influencing their occurrence. A total of 2451 records of 4 triatomine species (Panstrongylus geniculatus, Rhodnius pallescens, R. prolixus, and Triatoma maculata) were analyzed. The variables that provided more information to explain the ecologic niche of these vectors were related to precipitation, altitude, and temperature. We found that the species with the broadest potential geographic distribution were P. geniculatus, R. pallescens, and R. prolixus. In general, the models predicted the highest occurrence probability of these vectors in the eastern slope of the Eastern Cordillera, the southern region of the Magdalena valley, and the Sierra Nevada of Santa Marta. PMID:28115946

  10. Antarctic ice shelf potentially stabilized by export of meltwater in surface river

    Science.gov (United States)

    Bell, Robin E.; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J.; Zappa, Christopher J.; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang

    2017-04-01

    Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks—interconnected streams, ponds and rivers—on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf’s meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica—contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.

  11. Insight into induced charges at metal surfaces and biointerfaces using a polarizable Lennard-Jones potential.

    Science.gov (United States)

    Geada, Isidro Lorenzo; Ramezani-Dakhel, Hadi; Jamil, Tariq; Sulpizi, Marialore; Heinz, Hendrik

    2018-02-19

    Metallic nanostructures have become popular for applications in therapeutics, catalysts, imaging, and gene delivery. Molecular dynamics simulations are gaining influence to predict nanostructure assembly and performance; however, instantaneous polarization effects due to induced charges in the free electron gas are not routinely included. Here we present a simple, compatible, and accurate polarizable potential for gold that consists of a Lennard-Jones potential and a harmonically coupled core-shell charge pair for every metal atom. The model reproduces the classical image potential of adsorbed ions as well as surface, bulk, and aqueous interfacial properties in excellent agreement with experiment. Induced charges affect the adsorption of ions onto gold surfaces in the gas phase at a strength similar to chemical bonds while ions and charged peptides in solution are influenced at a strength similar to intermolecular bonds. The proposed model can be applied to complex gold interfaces, electrode processes, and extended to other metals.

  12. Potential dependent adhesion forces on bare and underpotential deposition modified electrode surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Serafin, J.M.; Hsieh, S.J.; Monahan, J.; Gewirth, A.A. [Univ. of Illinois, Urbana, IL (United States)

    1998-12-03

    Adhesion force measurements are used to determine the potential dependence of the force of adhesion between a Si{sub 3}N{sub 4} cantilever and a Au(111) surface modified by the underpotential deposition (upd) of Bi or Cu in acid solution or by oxide formation. The measured work of adhesion is near zero for most of the potential region examined in Bi upd but rises after the formation of a full Bi monolayer. The work of adhesion is high at positive potentials for Cu upd but then decreases as the Cu partial and full monolayers are formed. The work of adhesion is low in the oxide region on Au(111) but rises following the sulfate disordering transition at 1.1 V vs NHE. These results are interpreted in terms of the degree of solvent order on the electrode surface.

  13. Xenognosin methylation is critical in defining the chemical potential gradient that regulates the potential distribution in Striga pathogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Fate, G.D.; Lynn, D.G. [Univ. of Chicago, IL (United States)

    1996-11-20

    Striga asiatica (Scrophulariaceae) is a parasitic plant requiring a host-derived signal, xenognosin, to initiate a cascade of events necessary for the establishment of host contact. By attempting to model the distribution of the xenognosin around the host, the activity of the signal is shown to be strongly dependent on the presence of another component in the host exudate. Surprisingly this component, characterized as 4,6-dimethoxy-2-[(8`Z.11`Z)-8`,11`, -14`-pentadecatriene]resorcinol, is structurally related and shares the same biosynthetic pathway as the xenognosin. This compound is shown to function as an antioxidant and its ability to enhance the activity of the xenognosin is consistent with its ability to extend its lifetime in the exudate. This endogenous antioxidant activity is required to explain the spatial sensing in the establishment of the host-parasite interface and its characterization provides insight into how chemical potential may be regulated within and around plant tissues. 23 refs., 7 figs., 1 tab.

  14. The potential distribution of bioenergy crops in Europe under present and future climate

    International Nuclear Information System (INIS)

    Tuck, Gill; Glendining, Margaret J.; Smith, Pete; Wattenbach, Martin; House, Jo I.

    2006-01-01

    We have derived maps of the potential distribution of 26 promising bioenergy crops in Europe, based on simple rules for suitable climatic conditions and elevation. Crops suitable for temperate and Mediterranean climates were selected from four groups: oilseeds (e.g. oilseed rape, sunflower), starch crops (e.g. potatoes), cereals (e.g. barley) and solid biofuel crops (e.g. sorghum, Miscanthus). The impact of climate change under different scenarios and GCMs on the potential future distribution of these crops was determined, based on predicted future climatic conditions. Climate scenarios based on four IPCC SRES emission scenarios, A1FI, A2, B1 and B2, implemented by four global climate models, HadCM3, CSIRO2, PCM and CGCM2, were used. The potential distribution of temperate oilseeds, cereals, starch crops and solid biofuels is predicted to increase in northern Europe by the 2080s, due to increasing temperatures, and decrease in southern Europe (e.g. Spain, Portugal, southern France, Italy, and Greece) due to increased drought. Mediterranean oil and solid biofuel crops, currently restricted to southern Europe, are predicted to extend further north due to higher summer temperatures. Effects become more pronounced with time and are greatest under the A1FI scenario and for models predicting the greatest climate forcing. Different climate models produce different regional patterns. All models predict that bioenergy crop production in Spain is especially vulnerable to climate change, with many temperate crops predicted to decline dramatically by the 2080s. The choice of bioenergy crops in southern Europe will be severely reduced in future unless measures are taken to adapt to climate change. (author)

  15. The pace of past climate change vs. potential bird distributions and land use in the United States.

    Science.gov (United States)

    Bateman, Brooke L; Pidgeon, Anna M; Radeloff, Volker C; VanDerWal, Jeremy; Thogmartin, Wayne E; Vavrus, Stephen J; Heglund, Patricia J

    2016-03-01

    Climate change may drastically alter patterns of species distributions and richness, but predicting future species patterns in occurrence is challenging. Significant shifts in distributions have already been observed, and understanding these recent changes can improve our understanding of potential future changes. We assessed how past climate change affected potential breeding distributions for landbird species in the conterminous United States. We quantified the bioclimatic velocity of potential breeding distributions, that is, the pace and direction of change for each species' suitable climate space over the past 60 years. We found that potential breeding distributions for landbirds have shifted substantially with an average velocity of 1.27 km yr(-1) , about double the pace of prior distribution shift estimates across terrestrial systems globally (0.61 km yr(-1) ). The direction of shifts was not uniform. The majority of species' distributions shifted west, northwest, and north. Multidirectional shifts suggest that changes in climate conditions beyond mean temperature were influencing distributional changes. Indeed, precipitation variables that were proxies for extreme conditions were important variables across all models. There were winners and losers in terms of the area of distributions; many species experienced contractions along west and east distribution edges, and expansions along northern distribution edges. Changes were also reflected in the potential species richness, with some regions potentially gaining species (Midwest, East) and other areas potentially losing species (Southwest). However, the degree to which changes in potential breeding distributions are manifested in actual species richness depends on landcover. Areas that have become increasingly suitable for breeding birds due to changing climate are often those attractive to humans for agriculture and development. This suggests that many areas might have supported more breeding bird

  16. Potential Cost-Effectiveness of Prenatal Distribution of Misoprostol for Prevention of Postpartum Hemorrhage in Uganda

    Science.gov (United States)

    Lubinga, Solomon J.; Atukunda, Esther C.; Wasswa-Ssalongo, George; Babigumira, Joseph B.

    2015-01-01

    Background In settings where home birth rates are high, prenatal distribution of misoprostol has been advocated as a strategy to increase access to uterotonics during the third stage of labor to prevent postpartum hemorrhage (PPH). Our objective was to project the potential cost-effectiveness of this strategy in Uganda from both governmental (the relevant payer) and modified societal perspectives. Methods and Findings To compare prenatal misoprostol distribution to status quo (no misoprostol distribution), we developed a decision analytic model that tracked the delivery pathways of a cohort of pregnant women from the prenatal period, labor to delivery without complications or delivery with PPH, and successful treatment or death. Delivery pathway parameters were derived from the Uganda Demographic and Health Survey. Incidence of PPH, treatment efficacy, adverse event and case fatality rates, access to misoprostol, and health resource use and cost data were obtained from published literature and supplemented with expert opinion where necessary. We computed the expected incidence of PPH, mortality, disability adjusted life years (DALYs), costs and incremental cost effectiveness ratios (ICERs). We conducted univariate and probabilistic sensitivity analyses to examine robustness of our results. In the base-case analysis, misoprostol distribution lowered the expected incidence of PPH by 1.0% (95% credibility interval (CrI): 0.55%, 1.95%), mortality by 0.08% (95% CrI: 0.04%, 0.13%) and DALYs by 0.02 (95% CrI: 0.01, 0.03). Mean costs were higher with prenatal misoprostol distribution from governmental by US$3.3 (95% CrI: 2.1, 4.2) and modified societal (by US$1.3; 95% CrI: -1.6, 2.8) perspectives. ICERs were US$191 (95% CrI: 82, 443) per DALY averted from a governmental perspective, and US$73 (95% CI: -86, 256) per DALY averted from a modified societal perspective. Conclusions Prenatal distribution of misoprostol is potentially cost-effective in Uganda and should be

  17. Evaluation of internal potential distribution and carrier extraction properties of organic solar cells through Kelvin probe and time-of-flight measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Yuya; Oda, Keisuke; Nakayama, Yasuo [Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522 (Japan); Noguchi, Yutaka, E-mail: noguchi@meiji.ac.jp; Ishii, Hisao, E-mail: ishii130@faculty.chiba-u.jp [Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522 (Japan); Center for Frontier Science, Chiba University, Chiba 263-8522 (Japan); Takahashi, Jun-ichi; Tokairin, Hiroshi [Advanced Technology Research Laboratories, Idemitsu Kosan Co., Ltd. Sodegaura 299-0293 (Japan)

    2014-09-21

    The carrier extraction property of a prototypical small molecule organic solar cell (OSC) composed of copper phthalocyanine (CuPc), C⁶⁰, and bathocuproine (BCP) was studied on the basis of the internal potential distribution and carrier dynamics in the device. The internal potential distribution in the OSC structure at the interfaces and in the bulk region was determined by the Kelvin probe method. Significant potential gradients were found in the CuPc film on indium tin oxide and in the C⁶⁰ film on CuPc, consistent with charge transfer through the contacts. Moreover, surface potential of the BCP layer grew linearly with increasing film thickness with a slope of ca. 35 mV/nm (giant surface potential: GSP), which indicated spontaneous orientation polarization in the film. The potential gradient and GSP significantly changed the built-in potential of the device. Current–voltage and modified time-of-flight measurements revealed that the BCP layer worked as an electron injection and extraction layer despite the wide energy gap. These results were discussed based on the contributions of GSP and the gap states in the BCP layer.

  18. Evaluation of internal potential distribution and carrier extraction properties of organic solar cells through Kelvin probe and time-of-flight measurements

    International Nuclear Information System (INIS)

    Tanaka, Yuya; Oda, Keisuke; Nakayama, Yasuo; Noguchi, Yutaka; Ishii, Hisao; Takahashi, Jun-ichi; Tokairin, Hiroshi

    2014-01-01

    The carrier extraction property of a prototypical small molecule organic solar cell (OSC) composed of copper phthalocyanine (CuPc), C 60 , and bathocuproine (BCP) was studied on the basis of the internal potential distribution and carrier dynamics in the device. The internal potential distribution in the OSC structure at the interfaces and in the bulk region was determined by the Kelvin probe method. Significant potential gradients were found in the CuPc film on indium tin oxide and in the C 60 film on CuPc, consistent with charge transfer through the contacts. Moreover, surface potential of the BCP layer grew linearly with increasing film thickness with a slope of ca. 35 mV/nm (giant surface potential: GSP), which indicated spontaneous orientation polarization in the film. The potential gradient and GSP significantly changed the built-in potential of the device. Current–voltage and modified time-of-flight measurements revealed that the BCP layer worked as an electron injection and extraction layer despite the wide energy gap. These results were discussed based on the contributions of GSP and the gap states in the BCP layer.

  19. Potential distribution of pine wilt disease under future climate change scenarios.

    Directory of Open Access Journals (Sweden)

    Akiko Hirata

    Full Text Available Pine wilt disease (PWD constitutes a serious threat to pine forests. Since development depends on temperature and drought, there is a concern that future climate change could lead to the spread of PWD infections. We evaluated the risk of PWD in 21 susceptible Pinus species on a global scale. The MB index, which represents the sum of the difference between the mean monthly temperature and 15 when the mean monthly temperatures exceeds 15°C, was used to determine current and future regions vulnerable to PWD (MB ≥ 22. For future climate conditions, we compared the difference in PWD risks among four different representative concentration pathways (RCPs 2.6, 4.5, 6.0, and 8.5 and two time periods (2050s and 2070s. We also evaluated the impact of climate change on habitat suitability for each Pinus species using species distribution models. The findings were then integrated and the potential risk of PWD spread under climate change was discussed. Within the natural Pinus distribution area, southern parts of North America, Europe, and Asia were categorized as vulnerable regions (MB ≥ 22; 16% of the total Pinus distribution area. Representative provinces in which PWD has been reported at least once overlapped with the vulnerable regions. All RCP scenarios showed expansion of vulnerable regions in northern parts of Europe, Asia, and North America under future climate conditions. By the 2070s, under RCP 8.5, an estimated increase in the area of vulnerable regions to approximately 50% of the total Pinus distribution area was revealed. In addition, the habitat conditions of a large portion of the Pinus distribution areas in Europe and Asia were deemed unsuitable by the 2070s under RCP 8.5. Approximately 40% of these regions overlapped with regions deemed vulnerable to PWD, suggesting that Pinus forests in these areas are at risk of serious damage due to habitat shifts and spread of PWD.

  20. Potential distribution of pine wilt disease under future climate change scenarios.

    Science.gov (United States)

    Hirata, Akiko; Nakamura, Katsunori; Nakao, Katsuhiro; Kominami, Yuji; Tanaka, Nobuyuki; Ohashi, Haruka; Takano, Kohei Takenaka; Takeuchi, Wataru; Matsui, Tetsuya

    2017-01-01

    Pine wilt disease (PWD) constitutes a serious threat to pine forests. Since development depends on temperature and drought, there is a concern that future climate change could lead to the spread of PWD infections. We evaluated the risk of PWD in 21 susceptible Pinus species on a global scale. The MB index, which represents the sum of the difference between the mean monthly temperature and 15 when the mean monthly temperatures exceeds 15°C, was used to determine current and future regions vulnerable to PWD (MB ≥ 22). For future climate conditions, we compared the difference in PWD risks among four different representative concentration pathways (RCPs 2.6, 4.5, 6.0, and 8.5) and two time periods (2050s and 2070s). We also evaluated the impact of climate change on habitat suitability for each Pinus species using species distribution models. The findings were then integrated and the potential risk of PWD spread under climate change was discussed. Within the natural Pinus distribution area, southern parts of North America, Europe, and Asia were categorized as vulnerable regions (MB ≥ 22; 16% of the total Pinus distribution area). Representative provinces in which PWD has been reported at least once overlapped with the vulnerable regions. All RCP scenarios showed expansion of vulnerable regions in northern parts of Europe, Asia, and North America under future climate conditions. By the 2070s, under RCP 8.5, an estimated increase in the area of vulnerable regions to approximately 50% of the total Pinus distribution area was revealed. In addition, the habitat conditions of a large portion of the Pinus distribution areas in Europe and Asia were deemed unsuitable by the 2070s under RCP 8.5. Approximately 40% of these regions overlapped with regions deemed vulnerable to PWD, suggesting that Pinus forests in these areas are at risk of serious damage due to habitat shifts and spread of PWD.

  1. Potential impacts of climate change on the winter distribution of Afro-Palaearctic migrant passerines

    DEFF Research Database (Denmark)

    Barbet-Massin, Morgane; Walther, Bruno A; Thuiller, Wilfried

    2009-01-01

    We modelled the present and future sub-Saharan winter distributions of 64 trans-Saharan migrant passerines to predict the potential impacts of climate change. These predictions used the recent ensemble modelling developments and the latest IPCC climatic simulations to account for possible...... changes in range size and location were spatially structured, with species that winter in southern and eastern Africa facing larger range contractions and shifts. Predicted changes in regional species richness for these long-distance migrants are increases just south of the Sahara and on the Arabian...... Peninsula and major decreases in southern and eastern Africa....

  2. Predicting the potential distribution in China of Euwallacea fornicates (Eichhoff) under current and future climate conditions

    OpenAIRE

    Ge, Xuezhen; Jiang, Chao; Chen, Linghong; Qiu, Shuang; Zhao, Yuxiang; Wang, Tao; Zong, Shixiang

    2017-01-01

    Euwallacea fornicatus (Eichhoff) is an important forest pest that has caused serious damage in America and Vietnam. In 2014, it attacked forests of Acer trialatum in the Yunnan province of China, creating concern in China?s Forestry Bureau. We used the CLIMEX model to predict and compare the potential distribution for E. fornicates in China under current (1981?2010) and projected climate conditions (2011?2040) using one scenario (RCP8.5) and one global climate model (GCM), CSIRO-Mk3-6-0. Unde...

  3. Sea surface temperature data from a world wide distribution from 01 January 1971 to 31 December 2000 (NODC Accession 0000712)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea surface temperature data were collected in a world wide distribution from January 1, 1971 to December 31, 2000. Data were submitted by Japan Meteorological...

  4. Characteristics and Distribution of Phosphorus in Surface Sediments of Limnetic Ecosystem in Eastern China.

    Directory of Open Access Journals (Sweden)

    Wenqiang Zhang

    Full Text Available Phosphorus (P is an essential nutrient for aquatic organisms; however, excessive P inflow to limnetic ecosystems can induce eutrophication. P concentrations in the rivers, wetlands and lakes of Eastern China have been amplified by fertilizer and sewage inputs associated with the development of industry and agriculture. Yet, knowledge of the distribution and speciation of P is lacking at the regional scale. We determined the distribution and speciation of P in limnetic ecosystems in Eastern China using Standards, Measurements and Testing (SMT and phosphorus nuclear magnetic resonance (31P-NMR. The results indicate that P pollution in surface sediments was serious. Inorganic P (Pi was the primary drive of variation in total P (TP among different river systems, and Pi accounted for 71% to 90% of TP in surface sediment in Eastern China. Also, the concentrations of TP and Pi varied among watersheds and Pi primarily drove the variation in TP in different watersheds. Sediments less than 10-cm deep served as the main P reservoir. Environmental factors affect the speciation and origin of P. NaOH-Pi, HCl-Pi and organic P (Po were related to pH accordingly at the regional scale. The physicochemical properties of sediments from different limnetic ecosystems affect the P speciation. HCl-Pi was higher in wetland sediments than in riverine and lake sediments in Eastern China. Conversely, NaOH-Pi was lowest in wetland sediments. Total Po concentration was lower in riverine sediments than in other sediments, but Mono-P was higher, with an average concentration of 48 mg kg-1. Diesters-P was highest in lake sediments. By revealing the regional distribution of TP, Pi and Po, this study will support eutrophication management in Eastern China.

  5. The Role of Anion Adsorption in the Effect of Electrode Potential on Surface Plasmon Resonance Response.

    Science.gov (United States)

    Laurinavichyute, Veronika K; Nizamov, Shavkat; Mirsky, Vladimir M

    2017-06-20

    Surface plasmon resonance, being widely used in bioanalytics and biotechnology, is influenced by the electrical potential of the resonant gold layer. To evaluate the mechanism of this effect, we have studied it in solutions of various inorganic electrolytes. The magnitude of the effect decreases according to the series: KBr>KCl>KF>NaClO 4 . The data were treated by using different models of the interface. A quantitative description was obtained for the model, which takes into account the local dielectric function of gold being affected by the free electron charge, diffuse ionic layer near the gold/water interface, and specific adsorption of halides to the gold surface with partial charge transfer. Taking into account that most biological experiments are performed in chloride-containing solutions, detailed analysis of the model at these conditions was performed. The results indicate that the chloride adsorption is the main mechanism for the influence of potential on the surface plasmon resonance. The dependencies of surface concentration and residual charge of chloride on the applied potential were determined. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Effects of Wearing Different Personal Equipment on Force Distribution at the Plantar Surface of the Foot

    Directory of Open Access Journals (Sweden)

    Christoph Schulze

    2013-01-01

    Full Text Available Background. The wearing of personal equipment can cause specific changes in muscle activity and posture. In the present study, we investigated the influence of differences in equipment related weight loading and load distribution on plantar pressure. In addition, we studied functional effects of wearing different equipment with a particular focus on relevant changes in foot shape. Methods. Static and dynamic pedobarography were performed on 31 male soldiers carrying increasing weights consisting of different items of equipment. Results. The pressure acting on the plantar surface of the foot increased with higher loading, both under static and dynamic conditions (p < 0.05. We observed an increase in the contact area (p < 0.05 and an influence of load distribution through different ways to carry the rifle. Conclusions. The wearing of heavier weights leads to an increase in plantar pressure and contact area. This may be caused by flattening of the transverse and longitudinal arches. The effects are more evident in subjects with flat feet deformities which seem to flatten at an earlier load condition with a greater amount compared to subjects with normal arches. Improving load distribution should be a main goal in the development of military equipment in order to prevent injuries or functional disorders of the lower extremity.

  7. Examining Urban Impervious Surface Distribution and Its Dynamic Change in Hangzhou Metropolis

    Directory of Open Access Journals (Sweden)

    Longwei Li

    2016-03-01

    Full Text Available Analysis of urban distribution and its expansion using remote sensing data has received increasing attention in the past three decades, but little research has examined spatial patterns of urban distribution and expansion with buffer zones in different directions. This research selected Hangzhou metropolis as a case study to analyze spatial patterns and dynamic changes based on time-series urban impervious surface area (ISA datasets. ISA was developed from Landsat imagery between 1991 and 2014 using a hybrid approach consisting of linear spectral mixture analysis, decision tree classifiers, and post-processing. The spatial patterns of ISA distribution and its dynamic changes in eight directions—east, southeast, south, southwest, west, northwest, north, and northeast—at the temporal scale were analyzed with a buffer zone-based approach. This research indicated that ISA can be extracted from Landsat imagery with both producer and user accuracies of over 90%. ISA in Hangzhou metropolis increased from 146 km2 in 1991 to 868 km2 in 2014. Annual ISA growth rates were between 15.6 km2 and 48.8 km2 with the lowest growth rate in 1994–2000 and the highest growth rate in 2005–2010. Urban ISA increase before 2000 was mainly due to infilling within the urban landscape, and, after 2005, due to urban expansion in the urban-rural interfaces. Urban expansion in this study area has different characteristics in various directions that are influenced by topographic factors and urban development policies.

  8. Soil surface organic layers in Arctic Alaska: spatial distribution, rates of formation, and microclimatic effects

    Science.gov (United States)

    Baughman, Carson A.; Mann, Daniel H.; Verbyla, David L.; Kunz, Michael L.

    2015-01-01

    Organic layers of living and dead vegetation cover the ground surface in many permafrost landscapes and play important roles in ecosystem processes. These soil surface organic layers (SSOLs) store large amounts of carbon and buffer the underlying permafrost and its contained carbon from changes in aboveground climate. Understanding the dynamics of SSOLs is a prerequisite for predicting how permafrost and carbon stocks will respond to warming climate. Here we ask three questions about SSOLs in a representative area of the Arctic Foothills region of northern Alaska: (1) What environmental factors control the thickness of SSOLs and the carbon they store? (2) How long do SSOLs take to develop on newly stabilized point bars? (3) How do SSOLs affect temperature in the underlying ground? Results show that SSOL thickness and distribution correlate with elevation, drainage area, vegetation productivity, and incoming solar radiation. A multiple regression model based on these correlations can simulate spatial distribution of SSOLs and estimate the organic carbon stored there. SSOLs develop within a few decades after a new, sandy, geomorphic surface stabilizes but require 500–700 years to reach steady state thickness. Mature SSOLs lower the growing season temperature and mean annual temperature of the underlying mineral soil by 8 and 3°C, respectively. We suggest that the proximate effects of warming climate on permafrost landscapes now covered by SSOLs will occur indirectly via climate's effects on the frequency, extent, and severity of disturbances like fires and landslides that disrupt the SSOLs and interfere with their protection of the underlying permafrost.

  9. Effect of electrode density and measurement noise on the spatial resolution of cortical potential distribution.

    Science.gov (United States)

    Ryynänen, Outi R M; Hyttinen, Jari A K; Laarne, Päivi H; Malmivuo, Jaakko A

    2004-09-01

    The purpose of the present study was to examine the spatial resolution of electroencephalography (EEG) by means of inverse cortical EEG solution. The main interest was to study how the number of measurement electrodes and the amount of measurement noise affects the spatial resolution. A three-layer spherical head model was used to obtain the source-field relationship of cortical potentials and scalp EEG field. Singular value decomposition was used to evaluate the spatial resolution with various measurement noise estimates. The results suggest that as the measurement noise increases the advantage of dense electrode systems is decreased. With low realistic measurement noise, a more accurate inverse cortical potential distribution can be obtained with an electrode system where the distance between two electrodes is as small as 16 mm, corresponding to as many as 256 measurement electrodes. In clinical measurement environments, it is always beneficial to have at least 64 measurement electrodes.

  10. Widespread distribution of OH/H2O on the lunar surface inferred from spectral data

    Science.gov (United States)

    Bandfield, Joshua L.; Poston, Michael J.; Klima, Rachel L.; Edwards, Christopher S.

    2018-02-01

    Remote-sensing data from lunar orbiters have revealed spectral features consistent with the presence of OH or H2O on the lunar surface. Analyses of data from the Moon Mineralogy Mapper spectrometer onboard the Chandrayaan-1 spacecraft have suggested that OH/H2O is recycled on diurnal timescales and persists only at high latitudes. However, the spatial distribution and temporal variability of the OH/H2O, as well as its source, remain uncertain. Here we incorporate a physics-based thermal correction into analysis of reflectance spectra from the Moon Mineralogy Mapper and find that prominent absorption features consistent with OH/H2O can be present at all latitudes, local times and surface types examined. This suggests the widespread presence of OH/H2O on the lunar surface without significant diurnal migration. We suggest that the spectra are consistent with the production of OH in space-weathered materials by the solar wind implantation of H+ and formation of OH at crystal defect sites, as opposed to H2O sourced from the lunar interior. Regardless of the specific composition or formation mechanism, we conclude that OH/H2O can be present on the Moon under thermal conditions more wide-ranging than previously recognized.

  11. Distribution of energy levels of quantum free particle on the Liouville surface and trace formulae

    International Nuclear Information System (INIS)

    Bleher, P.M.; Kosygin, D.V.; Sinai, Y.G.

    1995-01-01

    We consider the Weyl asymptotic formula [{E n ≤R 2 }=Area Q.R 2 /(4π)+n(R), for eigenvalues of the Laplace-Beltrami operator on a two-dimensional torus Q with a Liouville metric which is in a sense the most general case of an integrable metric. We prove that if the surface Q is non-degenerate then the remainder term n(R) has the form n(R)=R 1/2 θ(R), where θ(R) is an almost periodic function of the Besicovitch class B 1 , and the Fourier amplitudes and the Fourier frequencies of θ(R) can be expressed via lengths of closed geodesics on Q and other simple geometric characteristics of these geodesics. We prove then that if the surface Q is generic then the limit distribution of θ(R) has a density p(t), which is an entire function of t possessing an asymptotics on a real line, logp(t)∝-C ± t 4 as t→±∞. An explicit expression for the Fourier transform of p(t) via Fourier amplitudes of θ(R) is also given. We obtain the analogue of the Guillemin-Duistermaat trace formula for the Liouville surfaces and discuss its accuracy. (orig.)

  12. On the Pressure Distribution in a Porous Media under a Spherical Loading Surface

    Science.gov (United States)

    Wang, Qiuyun; Zhu, Zenghao; Nathan, Rungun; Wu, Qianhong

    2017-11-01

    The phenomenon of pressure generation and relaxation inside a porous media is widely observed in biological systems. Herein, we report a biomimetic study to examine the pressure distribution inside a soft porous layer when a spherical loaded surface suddenly impacts on it. A novel experimental setup was developed that includes a fully instrumented spherical piston and a soft fibrous porous layer underneath. Extensive experimental study was performed with different porous materials, different loadings and different sized loading surfaces. The pore pressure generation and the motion of the loading surface were recorded. A novel theoretical model was developed to characterize the pressure field during the process. Excellent agreement was observed between the experimental results and the theoretically predictions. It shows that the pressure generation is governed by the Brinkman parameter, α = h/Kp0.5, where h is the porous layer thickness, and Kp is the undeformed permeability. The study improves our understanding of the dynamic response of soft porous media under rapid compression. It has board impact on the study of transient load bearing in biological systems and industry applications. This work was supported by the National Science Foundation (NSF CBET) under Award #1511096.

  13. Analysis and applications of a frequency selective surface via a random distribution method

    International Nuclear Information System (INIS)

    Xie Shao-Yi; Huang Jing-Jian; Yuan Nai-Chang; Liu Li-Guo

    2014-01-01

    A novel frequency selective surface (FSS) for reducing radar cross section (RCS) is proposed in this paper. This FSS is based on the random distribution method, so it can be called random surface. In this paper, the stacked patches serving as periodic elements are employed for RCS reduction. Previous work has demonstrated the efficiency by utilizing the microstrip patches, especially for the reflectarray. First, the relevant theory of the method is described. Then a sample of a three-layer variable-sized stacked patch random surface with a dimension of 260 mm×260 mm is simulated, fabricated, and measured in order to demonstrate the validity of the proposed design. For the normal incidence, the 8-dB RCS reduction can be achieved both by the simulation and the measurement in 8 GHz–13 GHz. The oblique incidence of 30° is also investigated, in which the 7-dB RCS reduction can be obtained in a frequency range of 8 GHz–14 GHz. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  14. The distribution of star formation and metals in the low surface brightness galaxy UGC 628

    Science.gov (United States)

    Young, J. E.; Kuzio de Naray, Rachel; Wang, Sharon X.

    2015-09-01

    We introduce the MUSCEL Programme (MUltiwavelength observations of the Structure, Chemistry and Evolution of LSB galaxies), a project aimed at determining the star-formation histories of low surface brightness galaxies. MUSCEL utilizes ground-based optical spectra and space-based UV and IR photometry to fully constrain the star-formation histories of our targets with the aim of shedding light on the processes that led low surface brightness galaxies down a different evolutionary path from that followed by high surface brightness galaxies, such as our Milky Way. Here we present the spatially resolved optical spectra of UGC 628, observed with the VIRUS-P IFU at the 2.7-m Harlen J. Smith Telescope at the McDonald Observatory, and utilize emission-line diagnostics to determine the rate and distribution of star formation as well as the gas-phase metallicity and metallicity gradient. We find highly clustered star formation throughout UGC 628, excluding the core regions, and a log(O/H) metallicity around -4.2, with more metal-rich regions near the edges of the galactic disc. Based on the emission-line diagnostics alone, the current mode of star formation, slow and concentrated in the outer disc, appears to have dominated for quite some time, although there are clear signs of a much older stellar population formed in a more standard inside-out fashion.

  15. The distribution of sulfur dioxide and other infrared absorbers on the surface of Io

    Science.gov (United States)

    Carlson, R.W.; Smythe, W.D.; Lopes-Gautier, R. M. C.; Davies, A.G.; Kamp, L.W.; Mosher, J.A.; Soderblom, L.A.; Leader, F.E.; Mehlman, R.; Clark, R.N.; Fanale, F.P.

    1997-01-01

    The Galileo Near Infrared Mapping Spectrometer was used to investigate the distribution and properties of sulfur dioxide over the surface of Io, and qualitative results for the anti-Jove hemisphere are presented here. SO2, existing as a frost, is found almost everywhere, but with spatially variable concentration. The exceptions are volcanic hot spots, where high surface temperatures promote rapid vaporization and can produce SO2-free areas. The pervasive frost, if fully covering the cold surface, has characteristic grain sizes of 30 to 100 Urn, or greater. Regions of greater sulfur dioxide concentrations are found. The equatorial Colchis Regio area exhibits extensive snowfields with large particles (250 to 500 ??m diameter, or greater) beneath smaller particles. A weak feature at 3.15 ??m is observed and is perhaps due to hydroxides, hydrates, or water. A broad absorption in the 1 ??m region, which could be caused by iron-containing minerals, shows a concentration in Io'S southern polar region, with an absence in the Pele plume deposition ring. Copyright 1997 by the American Geophysical Union.

  16. Atom diffraction reveals the impact of atomic core electrons on atom-surface potentials.

    Science.gov (United States)

    Lonij, Vincent P A; Klauss, Catherine E; Holmgren, William F; Cronin, Alexander D

    2010-12-03

    We measured ratios of van der Waals potential coefficients (C3) for different atoms (Li, Na, K, and Rb) interacting with the same surface by studying atom diffraction from a nanograting. These measurements are a sensitive test of atomic structure calculations because C3 ratios are strongly influenced by core electrons and only weakly influenced by the permittivity and geometry of the surface. Our measurement uncertainty of 2% in the ratio C(3)(K)/C(3)(Na) is close to the uncertainty of the best theoretical predictions, and some of these predictions are inconsistent with our measurement.

  17. On the instabilities of a potential vortex with a free surface

    DEFF Research Database (Denmark)

    Mougel, J.; Fabre, D.; Lacaze, L.

    2017-01-01

    In this paper, we address the linear stability analysis of a confined potential vortex with a free surface. This particular flow has been recently used by Tophoj et al. (Phys. Rev. Lett., vol. 110(19), 2013, article 194502) as a model for the swirling flow of fluid in an open cylindrical containe...... the numerical and theoretical analysis presented. These different methods and observations allow to support the unstable wave coupling mechanism as the physical process at the origin of the polygonal patterns observed in free-surface rotating flows....

  18. Potential energy surfaces for N = Z, 20Ne-112Ba nuclei

    International Nuclear Information System (INIS)

    Mehta, M.S.; Gupta, Raj K.; Jha, T.K.; Patra, S.K.

    2004-01-01

    We have calculated the potential energy surfaces for N = Z, 20 Ne- 112 Ba nuclei in an axially deformed relativistic mean field approach. A quadratic constraint scheme is applied to determine the complete energy surface for a wide range of the quadrupole deformation. The NL3, NL-RAl and TM1 parameter sets are used. The phenomenon of (multiple) shape coexistence is studied and the calculated ground and excited state binding energies, quadrupole deformation parameters and root mean square (rms) charge radii are compared with the available experimental data and other theoretical predictions. (author)

  19. Surface-active biopolymers from marine bacteria for potential biotechnological applications

    Directory of Open Access Journals (Sweden)

    Karina Sałek

    2016-03-01

    Full Text Available Surface-active agents are amphiphilic chemicals that are used in almost every sector of modern industry, the bulk of which are produced by organo-chemical synthesis. Those produced from biological sources (biosurfactants and bioemulsifiers, however, have gained increasing interest in recent years due to their wide structural and functional diversity, lower toxicities and high biodegradability, compared to their chemically-synthesised counterparts. This review aims to present a general overview on surface-active agents, including their classification, where new types of these biomolecules may lay awaiting discovery, and some of the main bottlenecks for their industrial-scale production. In particular, the marine environment is highlighted as a largely untapped source for discovering new types of surface-active agents. Marine bacteria, especially those living associated with micro-algae (eukaryotic phytoplankton, are a highly promising source of polymeric surface-active agents with potential biotechnological applications. The high uronic acids content of these macromolecules has been linked to conferring them with amphiphilic qualities, and their high structural diversity and polyanionic nature endows them with the potential to exhibit a wide range of functional diversity. Production yields (e.g. by fermentation for most microbial surface-active agents have often been too low to meet the volume demands of industry, and this principally remains as the most important bottleneck for their further commercial development. However, new developments in recombinant and synthetic biology approaches can offer significant promise to alleviate this bottleneck. This review highlights a particular biotope in the marine environment that offers promise for discovering novel surface-active biomolecules, and gives a general overview on specific areas that researchers and the industry could focus work towards increasing the production yields of microbial surface

  20. Feet on the potential energy surface, head in the pi clouds

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Quentin [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    This work presents explorations of the potential energy surface of clusters of atoms and of the interactions between molecules. First, structures of small aluminum clusters are examined and classified as ground states, transition states, or higher-order saddle points. Subsequently, the focus shifts to dispersion-dominated π-π interactions when the potential energy surfaces of benzene, substituted benzene, and pyridine dimers are explored. Because DNA nucleotide bases can be thought of as substituted heterocycles, a natural extension of the substituted benzene and pyridine investigations is to model paired nucleotide bases. Finally, the success of the dispersion studies inspires the development of an extension to the computational method used, which will enable the dispersion energy to be modeled – and the potential energy surface explored – in additional chemical systems. The effective fragment potential (EFP) method is described, as well as various quantum mechanical methods. An ab inito quantum mechanical study of 13-atom aluminum clusters is described. EFP studies of aromatic dimers are reported in which dispersion energy makes a significant contribution to the attraction between monomers. Theory and code development toward a means of computing dispersion energy in mixed ab inito-EFP systems are described.

  1. Polycyclic aromatic hydrocarbons in surface soil across the Tibetan Plateau: Spatial distribution, source and air–soil exchange

    International Nuclear Information System (INIS)

    Wang, Chuanfei; Wang, Xiaoping; Gong, Ping; Yao, Tandong

    2014-01-01

    There are limited data on polycyclic aromatic hydrocarbons (PAHs) in both the atmosphere and soil of the Tibetan Plateau (TP). Concentrations of PAHs were therefore measured in 13 XAD resin-based passive air samplers and 41 surface (0–5 cm) soil samples across the TP. The average concentration of atmospheric PAHs was 5.55 ng/m 3 , which was lower than that reported for other background areas, but higher than the Arctic. Concentrations in the soils fell in a wide range from 5.54 to 389 ng/g, with an average of 59.9 ng/g. Elevation was found to play an important role in determining the spatial distribution of soil PAHs. The air–soil exchange state showed that the soils of the TP will likely remain as a sink for high molecular weight PAHs, but may become a potential “secondary source” for low molecular weight PAHs. Highlights: • The levels of PAHs in air and soil of the Tibetan Plateau were relatively lower than other background region of world. • The soil PAHs concentration decreased with the increase of elevation. • The Tibetan Plateau will likely remain as a sink for high molecular weight PAHs. • The Tibetan Plateau may become a potential “secondary source” for low molecular weight PAHs. -- The Tibetan soil will likely remain as a sink for high molecular weight PAHs, but may become a potential “secondary source” for low molecular weight PAHs

  2. Potential impacts of changing supply-water quality on drinking water distribution: A review.

    Science.gov (United States)

    Liu, Gang; Zhang, Ya; Knibbe, Willem-Jan; Feng, Cuijie; Liu, Wentso; Medema, Gertjan; van der Meer, Walter

    2017-06-01

    Driven by the development of water purification technologies and water quality regulations, the use of better source water and/or upgraded water treatment processes to improve drinking water quality have become common practices worldwide. However, even though these elements lead to improved water quality, the water quality may be impacted during its distribution through piped networks due to the processes such as pipe material release, biofilm formation and detachment, accumulation and resuspension of loose deposits. Irregular changes in supply-water quality may cause physiochemical and microbiological de-stabilization of pipe material, biofilms and loose deposits in the distribution system that have been established over decades and may harbor components that cause health or esthetical issues (brown water). Even though it is clearly relevant to customers' health (e.g., recent Flint water crisis), until now, switching of supply-water quality is done without any systematic evaluation. This article reviews the contaminants that develop in the water distribution system and their characteristics, as well as the possible transition effects during the switching of treated water quality by destabilization and the release of pipe material and contaminants into the water and the subsequent risks. At the end of this article, a framework is proposed for the evaluation of potential transition effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. The influence of local glucose oxidase activity on the potential/current distribution on stainless steel: A study by the wire beam electrode method

    International Nuclear Information System (INIS)

    Wang Wei; Zhang Xia; Wang Jia

    2009-01-01

    The wire beam electrode (WBE) method was first used to study the activity of local glucose oxidase (GOD) on stainless steel surface in seawater. Glucose oxidase was immobilized in calcium alginate gel capsules, which were embedded in a layer of artificial biofilm (calcium alginate gel) on the WBE surface. The potential/current distributions on the WBE surface were mapped using a newly developed device for the WBE method in our lab. The results demonstrated that the catalysis of H 2 O 2 formation by GOD can produce local noble potential peaks and cathodic current zones on the stainless steel surface. An interesting fluctuant current distribution around cathodic zones was observed the first time. The potential and current maps showed that the enzyme heterogeneity of the artificial biofilm caused a corresponding electrochemical heterogeneity at the biofilm/metal interface. The application of the WBE method to ennoblement study enables us to observe the heterogeneous electrochemistry at biofilm/stainless steel interface directly, providing us with a powerful tool to investigate other biofilm-related processes such as microbially influenced corrosion (MIC).

  4. Potential energy surfaces for alkali plus noble gas pairs: a systematic comparison

    Science.gov (United States)

    Blank, L. Aaron; Kedziora, Gary S.; Weeks, David E.

    2010-02-01

    Optically Pumped Alkali Lasers (OPAL) involve interactions of alkali atoms with a buffer gas typically consisting of a noble gas together with C2H4. Line broadening mechanisms are of particular interest because they can be used to match a broad optical pumping source with relatively narrow alkali absorption spectra. To better understand the line broadening processes at work in OPAL systems we focus on the noble gas collisional partners. A matrix of potential energy surfaces (PES) has been generated at the multi-configurational self consistent field (MCSCF) level for M + Ng, where M=Li, Na, K, Rb, Cs and Ng=He, Ne, Ar. The PES include the X2Σ ground state surface and the A2II, B2Σ excited state surfaces. In addition to the MCSCF surfaces, PES for Li+He have been calculated at the multi-reference singles and doubles configuration interaction (MRSDCI) level with spin-orbit splitting effects included. These surfaces provide a way to check the qualitative applicability of the MCSCF calculations. They also exhibit the avoided crossing between the B2Σ and A2II1/2 surfaces that is partially responsible for collision induced relaxation from the 2P3/2 to the 2P1/2 atomic levels.

  5. Bohm potential effect on the propagation of electrostatic surface wave in semi-bounded quantum plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myoung-Jae [Department of Physics, Hanyang University, Seoul 04763 (Korea, Republic of); Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588 (Korea, Republic of); Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0407 (United States)

    2017-02-12

    High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained. - Highlights: • High frequency electrostatic wave propagation is investigated in a dense semi-bounded quantum plasma. • The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. • The quantum effect enhances the frequency of the wave especially in the high wave number regime. • The frequency of surface wave is found to be always lower than that of the bulk wave. • The group velocity of the surface wave for various quantum wave number is also obtained.

  6. N deposition affects allelopathic potential of Amaranthus retroflexus with different distribution regions

    Directory of Open Access Journals (Sweden)

    CONGYAN WANG

    Full Text Available ABSTRACT This study aims to determine the allelopathic potential of Amaranthus retroflexus (Ar with different climatic zones on seed germination and growth of A. tricolor (At treated with a gradient N addition. Ar leaf extracts only displayed significantly allelopathic potential on the underground growth of Ar but not the aboveground growth of At. The allelopathic potential of Ar leaf extracts on root length of At were enhanced under N addition and there may be a N-concentration-dependent relationship. The effects of the extracts of Ar leaves that collected from Zhenjiang on seed germination and growth of At may be higher than that collected from Jinan especially on root length of At under medium N addition. This reason may be the contained higher concentration of secondary metabolites for the leaves of plants that growths in high latitudes compare with that growth in low latitudes. This phenomenon may also partly be attributed to the fact that Ar originated in America and/or south-eastern Asia which have higher similarity climate conditions as Zhenjiang rather than Jinan. The allelopathic potential of Ar on seed germination and growth of acceptor species may play an important role in its successful invasion especially in the distribution region with low latitudes.

  7. [Species identification of freshwater snail Planorbella trivolvis and analysis of its potential distribution].

    Science.gov (United States)

    Li, Xiao-heng; Gao, Shi-tong; Gu, Wen-biao; Zhang, Yi; Guo, Yun-hai

    2015-06-01

    To identify the species classification of an ornamental Planorbidae from a flower market in Shanghai and analyze its potential distribution in China. In August 2013, six freshwater snail specimens were collected from the Wanshang flower market. The species was identified by morphology and molecular biology. An ecological niche model was constructed based on the native geographic presence occurrence data, and projected onto the whole of China to predict the potential distribution. Their shell external morphology suggested that the specimens belonged to Planorbella trivolvis (Say 1817) of Planorbidae, which is native in North America. The sequence data of a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) confirmed its identification. A total of 2 294 georeferenced occurrence points in North America were carried out from the Global Biodiversity Information Facility databases and 614 records with coordinates were used to produce a North American native niche model by a maximum entropy method (Maxent). The projection on China results suggested high probabilities of occurrence mostly in Henan Province and its borderland with nearby provinces. P. trivolvis is similarly with Biomphalaria species from shell morphology. It is the first records of the species in China, and the field dispersal is not clear.

  8. Theoretical Analysis of Potential and Current Distributions in Planar Electrodes of Lithium-ion Batteries

    International Nuclear Information System (INIS)

    Taheri, Peyman; Mansouri, Abraham; Yazdanpour, Maryam; Bahrami, Majid

    2014-01-01

    An analytical model is proposed to describe the two-dimensional distribution of potential and current in planar electrodes of pouch-type lithium-ion batteries. A concentration-independent polarization expression, obtained experimentally, is used to mimic the electrochemical performance of the battery. By numerically solving the charge balance equation on each electrode in conjugation with the polarization expression, the battery behavior during constant-current discharge processes is simulated. Our numerical simulations show that reaction current between the electrodes remains approximately uniform during most of the discharge process, in particular, when depth-of-discharge varies from 5% to 85%. This observation suggests to simplify the electrochemical behavior of the battery such that the charge balance equation on each electrode can be solved analytically to obtain closed-form solutions for potential and current density distributions. The analytical model shows fair agreement with numerical data at modest computational cost. The model is applicable for both charge and discharge processes, and its application is demonstrated for a prismatic 20 Ah nickel-manganese-cobalt lithium-ion battery during discharge processes

  9. The potential distribution of cassava mealybug (Phenacoccus manihoti, a threat to food security for the poor.

    Directory of Open Access Journals (Sweden)

    Tania Yonow

    Full Text Available The cassava mealybug is a clear and present threat to the food security and livelihoods of some of the world's most impoverished citizens. Niche models, such as CLIMEX, are useful tools to indicate where and when such threats may extend, and can assist with planning for biosecurity and the management of pest invasions. They can also contribute to bioeconomic analyses that underpin the allocation of resources to alleviate poverty. Because species can invade and establish in areas with climates that are different from those that are found in their native range, it is essential to define robust range-limiting mechanisms in niche models. To avoid spurious results when applied to novel climates, it is necessary to employ cross-validation techniques spanning different knowledge domains (e.g., distribution data, experimental results, phenological observations. We build upon and update a CLIMEX niche model by Parsa et al. (PloS ONE 7: e47675, correcting inconsistent parameters and re-fitting it based on a careful examination of geographical distribution data and relevant literature. Further, we consider the role of irrigation, the known distribution of cassava production and a targeted review of satellite imagery to refine, validate and interpret our model and results. In so doing, we bring new insights into the potential spread of this invasive insect, enabling us to identify potential bio-security threats and biological control opportunities. The fit of the revised model is improved, particularly in relation to the wet and dry limits to establishment, and the parameter values are biologically plausible and accord with published scientific literature.

  10. Patterns and controls of surface sediment distribution: West-central Florida inner shelf

    Science.gov (United States)

    Brooks, G.R.; Doyle, L.J.; Davis, R.A.; DeWitt, N.T.; Suthard, B.C.

    2003-01-01

    The west-central Florida inner shelf represents a transition between the quartz-dominated barrier-island system and the carbonate-dominated mid-outer shelf. Surface sediments exhibit a complex distribution pattern that can be attributed to multiple sediment sources and the ineffectiveness of physical processes for large-scale sediment redistribution. The west Florida shelf is the submerged extension of the Florida carbonate platform, consisting of a limestone karst surface veneered with a thin unconsolidated sediment cover. A total of 498 surface sediment samples were collected on the inner shelf and analyzed for texture and composition. Results show that sediment consists of a combination of fine quartz sand and coarse, biogenic carbonate sand and gravel, with variable but subordinate amounts of black, phosphorite-rich sand. The carbonate component consists primarily of molluskan fragments. The distribution is patchy and discontinuous with no discernible pattern, and the transition between sediment types is generally abrupt. Quartz-rich sediment dominates the inner 15 km north of the entrance into Tampa Bay, but south of the Bay is common only along the inner 3 km. Elsewhere, carbonate-rich sediment is the predominate sediment type, except where there is little sediment cover, in which cases black, phosphorite-rich sand dominates. Sediment sources are likely within, or around the periphery of the basin. Fine quartz sand is likely reworked from coastal units deposited during Pleistocene sea-level high stands. Carbonate sand and gravel is produced by marine organisms within the depositional basin. The black, phosphorite-rich sand likely originates from the bioerosion and reworking of the underlying strata that irregularly crop out within the study area. The distribution pattern contains elements of both storm- and tide-dominated siliciclastic shelves, but it is dictated primarily by the sediment source, similar to some carbonate systems. Other systems with similar

  11. Sensitivity analysis and parameter estimation for distributed hydrological modeling: potential of variational methods

    Directory of Open Access Journals (Sweden)

    W. Castaings

    2009-04-01

    Full Text Available Variational methods are widely used for the analysis and control of computationally intensive spatially distributed systems. In particular, the adjoint state method enables a very efficient calculation of the derivatives of an objective function (response function to be analysed or cost function to be optimised with respect to model inputs.

    In this contribution, it is shown that the potential of variational methods for distributed catchment scale hydrology should be considered. A distributed flash flood model, coupling kinematic wave overland flow and Green Ampt infiltration, is applied to a small catchment of the Thoré basin and used as a relatively simple (synthetic observations but didactic application case.

    It is shown that forward and adjoint sensitivity analysis provide a local but extensive insight on the relation between the assigned model parameters and the simulated hydrological response. Spatially distributed parameter sensitivities can be obtained for a very modest calculation effort (~6 times the computing time of a single model run and the singular value decomposition (SVD of the Jacobian matrix provides an interesting perspective for the analysis of the rainfall-runoff relation.

    For the estimation of model parameters, adjoint-based derivatives were found exceedingly efficient in driving a bound-constrained quasi-Newton algorithm. The reference parameter set is retrieved independently from the optimization initial condition when the very common dimension reduction strategy (i.e. scalar multipliers is adopted.

    Furthermore, the sensitivity analysis results suggest that most of the variability in this high-dimensional parameter space can be captured with a few orthogonal directions. A parametrization based on the SVD leading singular vectors was found very promising but should be combined with another regularization strategy in order to prevent overfitting.

  12. Heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan, China: distribution, contamination, and ecological risk assessment.

    Science.gov (United States)

    Chai, Liyuan; Li, Huan; Yang, Zhihui; Min, Xiaobo; Liao, Qi; Liu, Yi; Men, Shuhui; Yan, Yanan; Xu, Jixin

    2017-01-01

    Here, we aim to determine the distribution, ecological risk and sources of heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan Province, China. Sixty-four surface sediment samples were collected in 16 sites of the Xiangjiang River, and the concentrations of ten heavy metals and metalloids (Mn, Zn, Cr, V, Pb, Cu, As, Ni, Co, and Cd) in the sediment samples were investigated using an inductively coupled plasma mass spectrometer (ICP-MS) and an atomic fluorescence spectrophotometer (AFS), respectively. The results showed that the mean concentrations of the ten heavy metals and metalloids in the sediment samples followed the order Mn > Zn > Cr > V > Pb > Cu > As ≈ Ni >Co > Cd. The geoaccumulation index (I geo ), enrichment factor (EF), modified degree of contamination (mC d ), and potential ecological risk index (RI) revealed that Cd, followed by Pb, Zn, and Cu, caused severely contaminated and posed very highly potential ecological risk in the Xiangjiang River, especially in Shuikoushan of Hengyang, Xiawan of Zhuzhou, and Yijiawan of Xiangtan. The Pearson's correlation coefficient (PCC) analysis, principal component analysis (PCA), and hierarchical cluster analysis (HCA) indicated that the ten heavy metals and metalloids in the sampling sediments of the Xiangjiang River were classified into three groups: (1) Cd, Pb, Zn, and Cu which possibly originated from Shuikoushan, Xiawan, and Yijiawan clustering Pb-Zn mining and smelting industries; (2) Co, V, Ni, Cr, and Al from natural resources; and (3) Mn and As. Therefore, our results suggest that anthropogenic activities, especially mining and smelting, have caused severe contamination of Cd, Pb, Zn, and Cu and posed very high potential ecological risk in the Xiangjiang River.

  13. The geographic distribution of strontium isotopes in Danish surface waters - A base for provenance studies in archaeology, hydrology and agriculture

    DEFF Research Database (Denmark)

    Frei, Karin Margarita; Frei, Robert

    2011-01-01

    In this paper Sr isotope signatures are reported for 192 surface water (lakes/ponds and rivers/creeks) samples from within Denmark and an isotope distribution map is presented that may serve as a base for provenance applications, including archaeological migration studies, ground water – surface ...

  14. Electrical potential-assisted DNA hybridization. How to mitigate electrostatics for surface DNA hybridization.

    Science.gov (United States)

    Tymoczko, Jakub; Schuhmann, Wolfgang; Gebala, Magdalena

    2014-12-24

    Surface-confined DNA hybridization reactions are sensitive to the number and identity of DNA capture probes and experimental conditions such as the nature and the ionic strength of the electrolyte solution. When the surface probe density is high or the concentration of bulk ions is much lower than the concentration of ions within the DNA layer, hybridization is significantly slowed down or does not proceed at all. However, high-density DNA monolayers are attractive for designing high-sensitivity DNA sensors. Thus, circumventing sluggish DNA hybridization on such interfaces allows a high surface concentration of target DNA and improved signal/noise ratio. We present potential-assisted hybridization as a strategy in which an external voltage is applied to the ssDNA-modified interface during the hybridization process. Results show that a significant enhancement of hybridization can be achieved using this approach.

  15. Potentialities of some surface characterization techniques for the development of titanium biomedical alloys

    Directory of Open Access Journals (Sweden)

    P.S. Vanzillotta

    2004-09-01

    Full Text Available Bone formation around a metallic implant is a complex process that involves micro- and nanometric interactions. Several surface treatments, including coatings were developed in order to obtain faster osseointegration. To understand the role of these surface treatments on bone formation it is necessary to choose adequate characterization techniques. Among them, we have selected electron microscopy, profilometry, atomic force microscopy (AFM and X-ray photoelectron spectroscopy (XPS to describe them briefly. Examples of the potentialities of these techniques on the characterization of titanium for biomedical applications were also presented and discussed. Unfortunately more than one technique is usually necessary to describe conveniently the topography (scanning electron microsocopy, profilometry and/or AFM and the chemical state (XPS of the external layer of the material surface. The employment of the techniques above described can be useful especially for the development of new materials or products.

  16. Metrological Aspects of Surface Topographies Produced by Different Machining Operations Regarding Their Potential Functionality

    Directory of Open Access Journals (Sweden)

    Żak Krzysztof

    2017-06-01

    Full Text Available This paper presents a comprehensive methodology for measuring and characterizing the surface topographies on machined steel parts produced by precision machining operations. The performed case studies concern a wide spectrum of topographic features of surfaces with different geometrical structures but the same values of the arithmetic mean height Sa. The tested machining operations included hard turning operations performed with CBN tools, grinding operations with Al2O3 ceramic and CBN wheels and superfinish using ceramic stones. As a result, several characteristic surface textures with the Sa roughness parameter value of about 0.2 μm were thoroughly characterized and compared regarding their potential functional capabilities. Apart from the standard 2D and 3D roughness parameters, the fractal, motif and frequency parameters were taken in the consideration.

  17. Stair-Step Particle Flux Spectra on the Lunar Surface: Evidence for Nonmonotonic Potentials?

    Science.gov (United States)

    Collier, Michael R.; Newheart, Anastasia; Poppe, Andrew R.; Hills, H. Kent; Farrell, William M.

    2016-01-01

    We present examples of unusual "stair-step" differential flux spectra observed by the Apollo 14 Suprathermal Ion Detector Experiment on the lunar dayside surface in Earth's magnetotail. These spectra exhibit a relatively constant differential flux below some cutoff energy and then drop off precipitously, by about an order of magnitude or more, at higher energies. We propose that these spectra result from photoions accelerated on the lunar dayside by nonmonotonic potentials (i.e.,potentials that do not decay to zero monotonically) and present a model for the expected differential flux. The energy of the cutoff and the magnitude of the differential flux are related to the properties of the local space environment and are consistent with the observed flux spectra. If this interpretation is correct, these surface-based ion observations provide a unique perspective that both complements and enhances the conclusions obtained by remote-sensing orbiter observations on the Moon's exospheric and electrostatic properties.

  18. Prediction of Tetraoxygen Reaction Mechanism with Sulfur Atom on the Singlet Potential Energy Surface

    Directory of Open Access Journals (Sweden)

    Ashraf Khademzadeh

    2014-01-01

    Full Text Available The mechanism of S+O4 (D2h reaction has been investigated at the B3LYP/6-311+G(3df and CCSD levels on the singlet potential energy surface. One stable complex has been found for the S+O4 (D2h reaction, IN1, on the singlet potential energy surface. For the title reaction, we obtained four kinds of products at the B3LYP level, which have enough thermodynamic stability. The results reveal that the product P3 is spontaneous and exothermic with −188.042 and −179.147 kcal/mol in Gibbs free energy and enthalpy of reaction, respectively. Because P1 adduct is produced after passing two low energy level transition states, kinetically, it is the most favorable adduct in the 1S+1O4 (D2h atmospheric reactions.

  19. Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

    International Nuclear Information System (INIS)

    Osborn, David L.

    2017-01-01

    Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low temperature combustion and the oxidation of volatile organic compounds in earth’s atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization make characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, while master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

  20. Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

    Science.gov (United States)

    Osborn, David L.

    2017-05-01

    Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low-temperature combustion and in the oxidation of volatile organic compounds in Earth's atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization makes characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, and master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

  1. Systematic and efficient navigating potential energy surface: Data for silver doped gold clusters

    Directory of Open Access Journals (Sweden)

    Vitaly V. Chaban

    2016-06-01

    Full Text Available Locating global minimum of certain atomistic ensemble is known to be a highly challenging and resource consuming task. This dataset represents joint usage of the semi-empirical PM7 Hamiltonian, Broyden–Fletcher–Goldfarb–Shanno algorithm and basin hopping scheme to navigate a potential energy surface. The Au20 nanocluster was used for calibration as its global minimum structure is well-known. Furthermore, Au18Ag2 and Au15Ag5 were simulated for illustration of the algorithm performance. The work shows encouraging results and, particularly, underlines proper accuracy of PM7 as applied to this type of heavy metal systems. The reported dataset motivates to use the benchmarked method for studying potential energy surfaces of manifold systems and locate their global-minimum atomistic configurations.

  2. Dynamical image potential and induced forces for charged particles moving parallel to a solid surface

    International Nuclear Information System (INIS)

    Arista, N.R.

    1994-01-01

    The dynamical image potential and ensuing forces induced by a charged particle moving parallel to a solid surface are investigated by using a dielectric formulation for semi-infinite dispersive media. The adiabatic behavior of the field in the asymptotic range is discussed in a general way using a multipole expansion. Several calculations illustrate the behavior of the field using both a simple model, where the surface response is approximated by a single plasma resonance, and a more realistic representation of the medium based upon the empirical information on the optical constants for various solids (Al, Cu, Ag, and Au). The model parameters may be adjusted to provide very good agreement with the optical-data integrations of the stopping and lateral forces on the moving charge. On the other hand, important differences in the description of the wake potential using either the simple plasma resonance model, or the optical-data representation, are obtained for Cu, Ag, and Au

  3. Modification of transition's factor in the compact surface-potential-based MOSFET model

    Directory of Open Access Journals (Sweden)

    Kevkić Tijana

    2016-01-01

    Full Text Available The modification of an important transition's factor which enables continual behavior of the surface potential in entire useful range of MOSFET operation is presented. The various modifications have been made in order to obtain an accurate and computationally efficient compact MOSFET model. The best results have been achieved by introducing the generalized logistic function (GL in fitting of considered factor. The smoothness and speed of the transition of the surface potential from the depletion to the strong inversion region can be controlled in this way. The results of the explicit model with this GL functional form for transition's factor have been verified extensively with the numerical data. A great agreement was found for a wide range of substrate doping and oxide thickness. Moreover, the proposed approach can be also applied on the case where quantum mechanical effects play important role in inversion mode.

  4. Exploring a potential energy surface by machine learning for characterizing atomic transport

    Science.gov (United States)

    Kanamori, Kenta; Toyoura, Kazuaki; Honda, Junya; Hattori, Kazuki; Seko, Atsuto; Karasuyama, Masayuki; Shitara, Kazuki; Shiga, Motoki; Kuwabara, Akihide; Takeuchi, Ichiro

    2018-03-01

    We propose a machine-learning method for evaluating the potential barrier governing atomic transport based on the preferential selection of dominant points for atomic transport. The proposed method generates numerous random samples of the entire potential energy surface (PES) from a probabilistic Gaussian process model of the PES, which enables defining the likelihood of the dominant points. The robustness and efficiency of the method are demonstrated on a dozen model cases for proton diffusion in oxides, in comparison with a conventional nudge elastic band method.

  5. Physisorbed H{sub 2}@Cu(100) surface: Potential and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, Eddy; Houriez, Céline; Mitrushchenkov, Alexander O.; Guitou, Marie; Chambaud, Gilberte, E-mail: gilberte.chambaud@univ-mlv.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi-Echelle, UMR 8208 CNRS, 5 Boulevard Descartes, Champs sur Marne, F-77454 Marne-la-Vallée (France)

    2015-02-07

    Using an embedding approach, a 2-D potential energy function has been calculated to describe the physisorption interaction of H{sub 2} with a Cu(100) surface. For this purpose, a cluster model of the system calculated with highly correlated wavefunctions is combined with a periodic Density-Functional-Theory method using van der Waals-DF2 functional. Rotational and vibrational energy levels of physisorbed H{sub 2}, as well as D{sub 2} and HD, are calculated using the 2D embedding corrected potential energy function. The calculated transitions are in a very good agreement with Electron-Energy-Loss-Spectroscopy observations.

  6. Rotational Energy Transfer of N2 Gas Determined Using a New Ab Initio Potential Energy Surface

    Science.gov (United States)

    Huo, Winifred M.; Stallcop, James R.; Partridge, Harry; Langhoff, Stephen R. (Technical Monitor)

    1997-01-01

    Rotational energy transfer between two N2 molecules is a fundamental process of some importance. Exchange is expected to play a role, but its importance is somewhat uncertain. Rotational energy transfer cross sections of N2 also have applications in many other fields including modeling of aerodynamic flows, laser operations, and linewidth analysis in nonintrusive laser diagnostics. A number of N2-N2 rigid rotor potential energy surface (PES) has been reported in the literature.

  7. Ab initio Potential-Energy Surfaces and Electron-Spin-Exchange Cross Sections for H-O2 Interactions

    Science.gov (United States)

    Stallcop, James R.; Partridge, Harry; Levin, Eugene

    1996-01-01

    Accurate quartet- and doublet-state potential-energy surfaces for the interaction of a hydrogen atom and an oxygen molecule in their ground states have been determined from an ab initio calculation using large-basis sets and the internally contracted multireference configuration interaction method. These potential surfaces have been used to calculate the H-O2 electron-spin-exchange cross section; the square root of the cross section (in a(sub 0)), not taking into account inelastic effects, can be obtained approximately from the expressions 2.390E(sup -1/6) and 5.266-0.708 log10(E) at low and high collision energies E (in E(sub h)), respectively. These functional forms, as well as the oscillatory structure of the cross section found at high energies, are expected from the nature of the interaction energy. The mean cross section (the cross section averaged over a Maxwellian velocity distribution) agrees reasonably well with the results of measurements.

  8. Sustained distribution of aerosolized PEGylated liposomes in epithelial lining fluids on alveolar surfaces.

    Science.gov (United States)

    Kaneko, Keita; Togami, Kohei; Yamamoto, Eri; Wang, Shujun; Morimoto, Kazuhiro; Itagaki, Shirou; Chono, Sumio

    2016-10-01

    The distribution characteristics of aerosolized PEGylated liposomes in alveolar epithelial lining fluid (ELF) were examined in rats, and the ensuing mechanisms were investigated in the in vitro uptake and protein adsorption experiments. Nonmodified or PEGylated liposomes (particle size 100 nm) were aerosolized into rat lungs. PEGylated liposomes were distributed more sustainably in ELFs than nonmodified liposomes. Furthermore, the uptake of PEGylated liposomes by alveolar macrophages (AMs) was less than that of nonmodified liposomes. In further in vitro uptake experiments, nonmodified and PEGylated liposomes were opsonized with rat ELF components and then added to NR8383 cells as cultured rat AMs. The uptake of opsonized PEGylated liposomes by NR8383 cells was lower than that of opsonized nonmodified liposomes. Moreover, the protein absorption levels in opsonized PEGylated liposomes were lower than those in opsonized nonmodified liposomes. These findings suggest that sustained distributions of aerosolized PEGylated liposomes in ELFs reflect evasion of liposomal opsonization with surfactant proteins and consequent reductions in uptake by AMs. These data indicate the potential of PEGylated liposomes as aerosol-based drug delivery system that target ELF for the treatment of respiratory diseases.

  9. Technical assessment of forest road network using Backmund and surface distribution algorithm in a hardwood forest of Hyrcanian zone

    Energy Technology Data Exchange (ETDEWEB)

    Parsakhoo, P.

    2016-07-01

    Aim of study: Corrected Backmund and Surface Distribution Algorithms (SDA) for analysis of forest road network are introduced and presented in this study. Research was carried out to compare road network performance between two districts in a hardwood forest. Area of study: Shast Kalateh forests, Iran. Materials and methods: In uncorrected Backmund algorithm, skidding distance was determined by calculating road density and spacing and then it was designed as Potential Area for Skidding Operations (PASO) in ArcGIS software. To correct this procedure, the skidding constraint areas were taken using GPS and then removed from PASO. In SDA, shortest perpendicular distance from geometrical center of timber compartments to road was measured at both districts. Main results: In corrected Backmund, forest openness in district I and II were 70.3% and 69.5%, respectively. Therefore, there was little difference in forest openness in the districts based on the uncorrected Backmund. In SDA, the mean distance from geometrical center of timber compartments to the roads of districts I and II were 199.45 and 149.31 meters, respectively. Forest road network distribution in district II was better than that of district I relating to SDA. Research highlights: It was concluded that uncorrected Backmund was not precise enough to assess forest road network, while corrected Backmund could exhibit a real PASO by removing skidding constraints. According to presented algorithms, forest road network performance in district II was better than district I. (Author)

  10. Technical assessment of forest road network using Backmund and surface distribution algorithm in a hardwood forest of Hyrcanian zone

    Directory of Open Access Journals (Sweden)

    Aidin Parsakhoo

    2016-07-01

    Full Text Available Aim of study: Corrected Backmund and Surface Distribution Algorithms (SDA for analysis of forest road network are introduced and presented in this study. Research was carried out to compare road network performance between two districts in a hardwood forest. Area of study: Shast Kalateh forests, Iran. Materials and methods: In uncorrected Backmund algorithm, skidding distance was determined by calculating road density and spacing and then it was designed as Potential Area for Skidding Operations (PASO in ArcGIS software. To correct this procedure, the skidding constraint areas were taken using GPS and then removed from PASO. In SDA, shortest perpendicular distance from geometrical center of timber compartments to road was measured at both districts. Main results: In corrected Backmund, forest openness in district I and II were 70.3% and 69.5%, respectively. Therefore, there was little difference in forest openness in the districts based on the uncorrected Backmund. In SDA, the mean distance from geometrical center of timber compartments to the roads of districts I and II were 199.45 and 149.31 meters, respectively. Forest road network distribution in district II was better than that of district I relating to SDA. Research highlights: It was concluded that uncorrected Backmund was not precise enough to assess forest road network, while corrected Backmund could exhibit a real PASO by removing skidding constraints. According to presented algorithms, forest road network performance in district II was better than district I.

  11. Temperature effect of irradiated target surface on distribution of nanoparticles formed by implantation

    CERN Document Server

    Stepanov, A L; Popok, V N

    2001-01-01

    The composition layers, containing the metal nanoparticles, synthesized thorough implantation of the Ag sup + ions with the energy of 60 keV and the dose of 3 x 10 sup 1 sup 6 ion/cm sup 2 into the sodium-calcium silicate glass by the ion current of 3 mu A/cm sup 2 and the sublayer temperature of 35 deg C are studied. The obtained implantation results are analyzed in dependence on the temperature effects, developing for the glass samples of various thickness. The data on the silver distribution, the metal nanoparticles formation and growth by depth are obtained from the optical reflection spectra. It is demonstrated that minor changes in the surface temperature of the irradiated glass sublayer lead to noticeable diversities in the regularities of the nanoparticles formation in the sample volume

  12. Transmission comb of a distributed Bragg reflector with two surface dielectric gratings

    KAUST Repository

    Zhao, Xiaobo

    2016-02-19

    The transmission behaviour of a distributed Bragg reector (DBR) with surface dielectric gratings on top and bottom is studied. The transmission shows a comb-like spectrum in the DBR band gap, which is explained in the Fano picture. The number density of the transmission peaks increases with increasing number of cells of the DBR, while the ratio of the average full width at half maximum to the corresponding average free spectral range, being only few percent for both transversal electric and magnetic waves, is almost invariant. The transmission peaks can be narrower than 0.1 nm and are fully separated from each other in certain wavebands. We further prove that the transmission combs are robust against randomness in the heights of the DBR layers. Therefore, the proposed structure is a candidate for an ultra-narrow-band multichannel filter or polarizer.

  13. Global Cr-isotope distributions in surface seawater and incorporation of Cr isotopes into carbonate shells

    DEFF Research Database (Denmark)

    Paulukat, Cora Stefanie; Frei, Robert; Vögelin, Andrea Regula

    In this study we present the Cr-isotope composition of surface seawater from several locations worldwide. In addition to the samples from the oceans (Atlantic Ocean, Pacific Ocean, Southern Ocean and Artic Ocean) we analysed water samples from areas with a more limited water exchange (Mediterranean...... Sea, Baltic Sea, Øresund and Kattegat). The long residence time of Cr (7,000 to 40,000 years) [1,2,3] relative to the ocean mixing time (1,000 to 2,000 years) [4] could lead to the expectation that the Cr concentration and Cr-isotope distribution are homogeneous in the oceans. However, our seawater...... observed a negative correlation between the Cr-isotope composition and the Cr concentration. Exceptions are samples from the Baltic Sea/Øresund, which are isotopically light despite low Cr concentrations (~0.1-0.2 ppb). In addition to the seawater data, we measured Cr isotopes in modern biologically...

  14. Structural instability of sheath potential distribution and its possible implications for the L/H transition in tokamak plasmas

    International Nuclear Information System (INIS)

    Yoshida, Zensho; Yamada, Hiroshi.

    1988-07-01

    The Bohm equation of electrostatic potential distributions in one-dimensional plasmas has been studied for various Mach numbers and plasma potentials. Solvability and structural stability have been discussed using the Sagdeev potential. Implications of the structural stability for the L/H transitions in tokamak plasmas has been also discussed. (author)

  15. Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions

    Science.gov (United States)

    Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

    1994-01-01

    Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. For some dynamics methods, global potential energy surfaces are required. In this case, it is necessary to obtain the energy at a complete sampling of all the possible arrangements of the nuclei, which are energetically accessible, and then a fitting function must be obtained to interpolate between the computed points. In other cases, characterization of the stationary points and the reaction pathway connecting them is sufficient. These properties may be readily obtained using analytical derivative methods. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives usefull results for a number of chemically important systems. The talk will focus on a number of applications including global potential energy surfaces, H + O2, H + N2, O(3p) + H2, and reaction pathways for complex reactions, including reactions leading to NO and soot formation in hydrocarbon combustion.

  16. Distribution of cardiac sodium channels in clusters potentiates ephaptic interactions in the intercalated disc.

    Science.gov (United States)

    Hichri, Echrak; Abriel, Hugues; Kucera, Jan P

    2018-02-15

    It has been proposed that ephaptic conduction, relying on interactions between the sodium (Na + ) current and the extracellular potential in intercalated discs, might contribute to cardiac conduction when gap junctional coupling is reduced, but this mechanism is still controversial. In intercalated discs, Na + channels form cluste