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Sample records for determine transport properties

  1. A Genetic Algorithm for Simultaneous Determination of Thin Films Thermal Transport Properties and Contact Resistance

    Institute of Scientific and Technical Information of China (English)

    Zhengxing HUANG; Zhen'an TANG; Ziqiang XU; Haitao DING; Yuqin GU

    2006-01-01

    A genetic algorithm (GA) was studied to simultaneously determine the thermal transport properties and the contact resistance of thin films deposited on a thick substrate. A pulsed photothermal reflectance (PPR) system was employed for the measurements. The GA was used to extract the thermal properties. Measurements were performed on SiO2 thin films of different thicknesses on silicon substrate. The results show that the GA accompanied with the PPR system is useful for the simultaneous determination of thermal properties of thin films on a substrate.

  2. The determination of ionic transport properties at high pressures in a diamond anvil cell

    Science.gov (United States)

    Wang, Qinglin; Liu, Cailong; Han, Yonghao; Gao, Chunxiao; Ma, Yanzhang

    2016-12-01

    A two-electrode configuration was adopted in an in situ impedance measurement system to determine the ionic conductivity at high pressures in a diamond anvil cell. In the experimental measurements, Mo thin-films were specifically coated on tops of the diamond anvils to serve as a pair of capacitance-like electrodes for impedance spectrum measurements. In the spectrum analysis, a Warburg impedance element was introduced into the equivalent circuit to reveal the ionic transport property among other physical properties of a material at high pressures. Using this method, we were able to determine the ionic transport character including the ionic conductivity and the diffusion coefficient of a sodium azide solid to 40 GPa.

  3. Can the Transport Properties of Molten Salts and Ionic Liquids Be Used To Determine Ion Association?

    Science.gov (United States)

    Harris, Kenneth R

    2016-12-01

    There have long been arguments supporting the concept of ion association in molten salts and ionic liquids, largely based on differences between the conductivity and that predicted from self-diffusion coefficients by the Nernst-Einstein equation for noninteracting ions. It is known from molecular dynamics simulations that even simple models based on charged hard spheres show such a difference due to the (anti)-correlation of ion motions. Formally this is expressed as a difference between the velocity cross-correlation coefficient of the oppositely charged ions and the mean of those for the two like-charged ions. This article examines molten salt and ionic liquid transport property data, comparing simple and model associated salts (ZnCl2, PbCl2, and TlCl) including weakly dissociated molecular liquids (H2O, HCOOH, H2SO4). Analysis employing Laity resistance coefficients (rij) shows that the common ion-association rationalization is flawed, consistent with recent direct measurements of the degree of ionicity in ionic liquid chlorides and with theoretical studies. However, the protic ionic liquids [PyrOMe][BF4] and [DBUH][CH3SO3] have larger than usual NE deviation parameters (>0.5), and large negative like-ion rii, analogous to those of ZnCl2. Structural, spectroscopic, and theoretical studies are suggested to determine whether these are indeed genuine examples of association.

  4. Confined Water Determines Transport Properties of Guest Molecules in Narrow Pores.

    Science.gov (United States)

    Phan, Anh; Cole, David R; Weiß, R Gregor; Dzubiella, Joachim; Striolo, Alberto

    2016-08-23

    We computed the transport of methane through 1 nm wide slit-shaped pores carved out of solid substrates. Models for silica, magnesium oxide, and alumina were used as solid substrates. The pores were filled with water. The results show that the methane permeability through the hydrated pores is strongly dependent on the solid substrate. Detailed analysis of the simulated systems reveals that local properties of confined water, including its structure, and more importantly, evolution of solvation free energy and hydrogen bond structure are responsible for the pronounced differences observed. The simulations are extended to multicomponent systems representative of natural gas, containing methane, ethane, and H2S. The results show that all pores considered have high affinity for H2S, moderate affinity for methane, and low affinity for ethane. The H2S/methane transport selectivity through the hydrated alumina pore is comparable, or superior, to that reported for existing commercial membranes. A multiscale approach was then implemented to demonstrate that a Smoluchowski one-dimensional model is able to reproduce the molecular-level results for short pores when appropriate values for the local self-diffusion coefficients are used as input parameters. We propose that the model can be extended to predict methane transport through uniform hydrated pores of macroscopic length. When verified by experiments, our simulation results could have important implications in applications such as natural gas sweetening and predictions of methane migration through hydraulically fractured shale formations.

  5. Molecular simulations for determination of transport properties of nano-composites

    Science.gov (United States)

    Mahajan, Sanket S.

    In several recent applications, including those aimed at developing novel thermal interface materials, nano-particulate systems have been proposed to improve the effective behavior of the system. One critical challenge in using nano-particulate systems is the lack of knowledge regarding their thermal conductivity. In this thesis, techniques based on Molecular Dynamics (MD) simulations are developed to determine transport properties of various types of homogeneous and inhomogeneous systems. In particular, the thermal conductivity values of bulk silica, silica nano-wire and nano-particle are determined using MD simulations. The equilibrium MD simulations of nano-particles using Green-Kubo relations are demonstrated to be computationally very expensive and unsuitable for nano-scale systems. The reverse non-equilibrium MD method of imposing heat flux is shown to be efficient and more accurate. The method is first demonstrated on bulk amorphous silica and silica nano-wires. The mean thermal conductivity values for bulk silica and silica nano-wire are estimated to be 1.221 W/mK and 1.430 W/mK, respectively. To model nano-particles, a novel methodology inspired by the imposition of heat flux technique, is developed by dividing the nano-particle into concentric shells so as to capture the naturally radial mode of heat transfer. The mean thermal conductivity value of a 600-atom silica nano-particle obtained using this approach is 0.589 W/mK. This value is ˜50-60% lower than those of bulk silica and silica nano-wire. The above developed technique for estimating the thermal conductivity of nano-structured homogeneous systems is naturally extended to determine the Kapitza resistance between solid-solid interfaces. The systems considered are interfaces between Si-SiO2 and Si-HfO2 thin films. For the Si-SiO2 interface, the average Kapitza resistance for ˜8 A thick oxide layer system is 0.503 x 10-9 m2K/W and for the ˜11.5 A thick oxide layer system is 0.518 x 10-9 m 2K/W. For

  6. In Situ Determination of the Transport Properties of Near-Surface Concrete Using AC Impedance Spectroscopy Techniques

    Directory of Open Access Journals (Sweden)

    Lipeng Wu

    2016-01-01

    Full Text Available The durability of existing concrete structures has increasingly attracted widespread attention in recent years. The phenomenon of performance degradation is often associated with the intrusion of hazardous ions from outside. As the first barrier to external substances intrusion, the near-surface concrete plays an important role in durability. So the performance of in-service concrete structures often depends on the transport properties of the near-surface concrete. Accordingly, information on service conditions and life prediction can be obtained by testing these transport properties. In this paper, an in situ method for chloride ion diffusion coefficient determination is proposed based on the relationship between the alternating current impedance spectroscopy parameters and the chloride ion diffusion coefficient. By a rational design, the new method can synthetically reflect the transport properties of near-surface concrete and is not affected by the presence of the reinforcing bar. In addition, the experimental results show that the method is in good agreement with “PERMIT” migration test which has been widely used. The proposed method is less time consuming and nondestructive and has good reproducibility.

  7. Accurate determination of electronic transport properties of silicon wafers by nonlinear photocarrier radiometry with multiple pump beam sizes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qian [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Bincheng, E-mail: bcli@uestc.ac.cn [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-12-07

    In this paper, photocarrier radiometry (PCR) technique with multiple pump beam sizes is employed to determine simultaneously the electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) of silicon wafers. By employing the multiple pump beam sizes, the influence of instrumental frequency response on the multi-parameter estimation is totally eliminated. A nonlinear PCR model is developed to interpret the PCR signal. Theoretical simulations are performed to investigate the uncertainties of the estimated parameter values by investigating the dependence of a mean square variance on the corresponding transport parameters and compared to that obtained by the conventional frequency-scan method, in which only the frequency dependences of the PCR amplitude and phase are recorded at single pump beam size. Simulation results show that the proposed multiple-pump-beam-size method can improve significantly the accuracy of the determination of the electronic transport parameters. Comparative experiments with a p-type silicon wafer with resistivity 0.1–0.2 Ω·cm are performed, and the electronic transport properties are determined simultaneously. The estimated uncertainties of the carrier lifetime, diffusion coefficient, and front surface recombination velocity are approximately ±10.7%, ±8.6%, and ±35.4% by the proposed multiple-pump-beam-size method, which is much improved than ±15.9%, ±29.1%, and >±50% by the conventional frequency-scan method. The transport parameters determined by the proposed multiple-pump-beam-size PCR method are in good agreement with that obtained by a steady-state PCR imaging technique.

  8. In silico predictive model to determine vector-mediated transport properties for the blood–brain barrier choline transporter

    Directory of Open Access Journals (Sweden)

    Shityakov S

    2014-09-01

    Full Text Available Sergey Shityakov, Carola Förster Department of Anaesthesia and Critical Care, University of Würzburg, Würzburg, Germany Abstract: The blood–brain barrier choline transporter (BBB-ChT may have utility as a drug delivery vector to the central nervous system (CNS. We therefore initiated molecular docking studies with the AutoDock and AutoDock Vina (ADVina algorithms to develop predictive models for compound screening and to identify structural features important for binding to this transporter. The binding energy predictions were highly correlated with r2=0.88, F=692.4, standard error of estimate =0.775, and P-value<0.0001 for selected BBB-ChT-active/inactive compounds (n=93. Both programs were able to cluster active (Gibbs free energy of binding <−6.0 kcal*mol-1 and inactive (Gibbs free energy of binding >−6.0 kcal*mol-1 molecules and dock them significantly better than at random with an area under the curve value of 0.86 and 0.84, respectively. In ranking smaller molecules with few torsional bonds, a size-related bias in scoring producing false-negative outcomes was detected. Finally, important blood–brain barrier parameters, such as the logBBpassive and logBBactive values, were assessed to predict compound transport to the CNS accurately. Knowledge gained from this study is useful to better understand the binding requirements in BBB-ChT, and until such time as its crystal structure becomes available, it may have significant utility in developing a highly predictive model for the rational design of drug-like compounds targeted to the brain. Keywords: blood–brain barrier choline transporter, central nervous system, drug delivery vector, molecular docking, virtual screening, Gibbs free energy of binding, diffusion

  9. Determination of transport properties and optimization of lithium-ion batteries

    Science.gov (United States)

    Stewart, Sarah Grace

    We have adapted the method of restricted diffusion to measure diffusion coefficients in lithium-battery electrolytes using Ultra-Violent-Visible (UV-Vis) absorption. The use of UV-Vis absorption reduces the likelihood of side reactions. Here we describe the measurement of the diffusion coefficient in lithium-battery electrolytic solutions. The diffusion coefficient is seen to decrease with increasing concentration according to the following: D = 3.018·10-5 exp(-0.357c), for LiPF 6 in acetonitrile and D = 2.582·10-5 exp(-2.856c) for LiPF6 in EC:DEC (with D in cm2/s and c in moles per liter). This technique may be useful for any liquid solution with a UV-active species of D greater than 10-6 cm2/s. Activity coefficients were measured in concentration cell and melting-point-depression experiments. Results from concentration-cell experiments are presented for solutions of lithium hexafluorophosphate (LiPF6) in propylene carbonate (PC) as well as in a 1:1 by weight solution of ethylene carbonate (EC) and ethyl methyl carbonate (EMC). Heat capacity results are also presented. The thermodynamic factor of LiPF6 solutions in EC varies between ca. 1.33 and ca. 6.10 in the concentration range ca. 0.06 to 1.25 M (which appears to be a eutectic point). We show that the solutions of LiPF6 investigated are not ideal but that an assumption of ideality for these solutions may overestimate the specific energy of a lithium-ion cell by only 0.6%. The thermodynamic and transport properties that we have measured are used in a system model. We have used this model to optimize the design of an asymmetric-hybrid system. This technology attempts to bridge the gap in energy density between a battery and supercapacitor. In this system, the positive electrode stores charge through a reversible, nonfaradaic adsorption of anions on the surface. The negative electrode is nanostructured Li4Ti 5O12, which reversibly intercalates lithium. We use the properties that we have measured in a system

  10. On the role of entropy in determining transport properties in metallic melts

    Science.gov (United States)

    Pasturel, A.; Jakse, N.

    2015-08-01

    We performed ab initio molecular dynamics simulations to study the relationship between dynamic and structural properties of liquid Al1-xNix alloys along the T = 1795 K isotherm. Our findings show a strong non-linear dependence of self-diffusion coefficients and the viscosity as a function of composition, in fair agreement with available experimental data. We demonstrate that this non-linear dependence can be related to the detailed description of local structural ordering and more particularly to a pronounced increase of icosahedral short range order (ISRO) in the Ni-rich composition range. We evidence that the composition dependence of local structural ordering is not captured by the Stokes-Einstein relation but can be understood in terms of the partial excess entropy approximated by the two-body contribution.

  11. A realistic transport model with pressure dependent parameters for gas flow in tight porous media with application to determining shale rock properties

    CERN Document Server

    Ali, Iftikhar

    2016-01-01

    Shale gas recovery has seen a major boom in recent years due to the increasing global energy demands; but the extraction technologies are very expensive. It is therefore important to develop realistic transport modelling and simulation methods, for porous rocks and porous media, that can compliment the field work. Here, a new nonlinear transport model for single phase gas flow in tight porous media is derived, incorporating many important physical processes that occur in such porous systems: continuous flow, transition flow, slip flow, Knudsen diffusion, adsorption and desorption in to and out of the rock material, and a correction for high flow rates (turbulence). This produces a nonlinear advection-diffusion type of partial differential equation (PDE) with pressure dependent model parameters and associated compressibility coefficients, and highly nonlinear apparent convective flux (velocity) and apparent diffusivity. An important application is to the determination of shale rock properties, such as porosity...

  12. Colligative thermoelectric transport properties in n-type filled CoSb3 determined by guest electrons in a host lattice

    Science.gov (United States)

    Lim, Young Soo; Park, Kwan-Ho; Tak, Jang Yeul; Lee, Soonil; Seo, Won-Seon; Park, Cheol-Hee; Kim, Tae Hoon; Park, PumSuk; Kim, Il-Ho; Yang, Jihui

    2016-03-01

    Among many kinds of thermoelectric materials, CoSb3 has received exceptional attention for automotive waste heat recovery. Its cage structure provides an ideal framework for the realization of phonon-glass electron-crystal strategy, and there have been numerous reports on the enhanced thermoelectric performance through the independent control of the thermal and electrical conductivity by introducing fillers into its cage sites. Herein, we report colligative thermoelectric transport properties in n-type CoSb3 from the viewpoint of "guest electrons in a host lattice." Both the Seebeck coefficient and the charge transport properties are fundamentally determined by the concentration of the guest electrons, which are mostly donated by the fillers, in the conduction band of the host CoSb3. Comparing this observation to our previous results, colligative relations for both the Seebeck coefficient and the mobility were deduced as functions of the carrier concentration, and thermoelectric transport constants were defined to predict the power factor in filled CoSb3. This discovery not only increases the degree of freedom for choosing a filler but also provides the predictability of power factor in designing and engineering the n-type filled CoSb3 materials.

  13. Transport Properties for Combustion Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N.J.; Bastein, L.; Price, P.N.

    2010-02-19

    This review examines current approximations and approaches that underlie the evaluation of transport properties for combustion modeling applications. Discussed in the review are: the intermolecular potential and its descriptive molecular parameters; various approaches to evaluating collision integrals; supporting data required for the evaluation of transport properties; commonly used computer programs for predicting transport properties; the quality of experimental measurements and their importance for validating or rejecting approximations to property estimation; the interpretation of corresponding states; combination rules that yield pair molecular potential parameters for unlike species from like species parameters; and mixture approximations. The insensitivity of transport properties to intermolecular forces is noted, especially the non-uniqueness of the supporting potential parameters. Viscosity experiments of pure substances and binary mixtures measured post 1970 are used to evaluate a number of approximations; the intermediate temperature range 1 < T* < 10, where T* is kT/{var_epsilon}, is emphasized since this is where rich data sets are available. When suitable potential parameters are used, errors in transport property predictions for pure substances and binary mixtures are less than 5 %, when they are calculated using the approaches of Kee et al.; Mason, Kestin, and Uribe; Paul and Warnatz; or Ern and Giovangigli. Recommendations stemming from the review include (1) revisiting the supporting data required by the various computational approaches, and updating the data sets with accurate potential parameters, dipole moments, and polarizabilities; (2) characterizing the range of parameter space over which the fit to experimental data is good, rather than the current practice of reporting only the parameter set that best fits the data; (3) looking for improved combining rules, since existing rules were found to under-predict the viscosity in most cases; (4

  14. Quantitative Mobility Spectrum Analysis for Determination of Electron and Magneto Transport Properties of Te-Doped GaSb

    Institute of Scientific and Technical Information of China (English)

    S. Acar; M. Kasap; B. Y. Isik; S.(O)zcelik; N. Tugluoglu; S. Karadeniz

    2005-01-01

    @@ Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped GaSb grown by the liquid encapsuled Czochralski technique are carried out as functions of temperature (35-350 K) and magnetic field (0-1.35 T).The power law model is used to explain the temperature-dependent resistivity. The magnetic-field-dependent data are analysed using the quantitative mobility spectrum analysis technique. The effect of individual band parameters (nL, nг, μL, μг, p and μp) on both the electron and magneto transports have been discussed. The EL -- Eг energy separation between the L and conduction band edges is also derived.

  15. Transport properties of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L.; Hablutzel, N. [Georgia Institute of Technology, Atlanta, GA (United States)

    1996-08-01

    Instrumentation and procedures have been completed for measurement of gas permeability and mass diffusivity of fiber preforms and porous materials. Results are reported for composites reinforced with Nicalon fiber in cloth lay-up and 3-D weave and with Nextel fiber in multi-layer braid. Measured permeability values range from near 100 to less than 0.1 darcies. Mass diffusivity is reported as a structure factor relating the diffusion through the porous material to that in free space. This measure is independent of the diffusing species and depends only on the pore structure of the material. Measurements are compared to predictions of a node-bond model for gas transport. Model parameters adjusted to match measured transport properties relate to physical microstructure features of the different architectures. Combination of this transport model with the CVI process model offers a predictive method to evaluate the densification behavior of various fiber preforms.

  16. Transport properties of organic liquids

    CERN Document Server

    Latini, G; Passerini, G

    2006-01-01

    The liquid state is possibly the most difficult and intriguing state of matter to model. Organic liquids are required, mainly as working fluids, in almost all industrial activities and in most appliances (e.g. in air conditioning). Transport properties (namely dynamic viscosity and thermal conductivity) are possibly the most important properties for the design of devices and appliances. The aim of this book is to present both theoretical approaches and the latest experimental advances on the issue, and to merge them into a wider approach. It concentrates on applicability of models.This book is

  17. Transport Properties of Binary Clusters

    Institute of Scientific and Technical Information of China (English)

    WAN Hai-Qing; ZHOU Yan-Hong; XU Ying

    2007-01-01

    We present first-principles studies on the transport properties of small silicon and aluminium clusters:Al2,Si2,Al4 and AISi sandwiched between two Al(100) electrodes.The variation of the equilibrium conductance as a function of contact distance for these two-probe systems is probed.Our results show that the transport properties are dependent on both the specific nanostructure and the separation distance between the central molecule and the electrodes.For equilibrium transport properties.the clusters with the similar structure show similar transmission spectra at large distances.the small difference can be explained by the electron filling.For current-voltage characteristics,all the clusters show the metallic behaviour at lower bias,however very different non-linear behaviour can be observed at higher bias.For AISi and Al2,when the distance between the central cluster and the electrodes is 3.5A.large negative differential resistance (NDR) can be found in the bias range 0.8V~1.4V.

  18. Electronic transport properties in graphene oxide frameworks

    Science.gov (United States)

    Zhu, P.; Cruz-Silva, E.; Meunier, V.

    2014-02-01

    The electronic transport properties in multiterminal graphene oxide framework (GOF) materials are investigated using a combination of theoretical and computational methods. GOFs make up four-terminal [origin=c]90H-shaped GNR-L-GNR junctions where sandwiched boronic acid molecules (L) are covalently linked to two graphene nanoribbons (GNRs) of different edge chiralities. The transport properties are governed by both tunneling and quasiresonant regimes. We determine how the presence of linker molecules affects the transport properties and establish that the through-molecule transport properties can be tuned by varying the chemical composition of the pillar molecules but are not significantly modified when changing the type of electrodes from zigzag GNRs to armchair GNRs. In addition, we find that in multilinker systems containing two parallel molecules in the device area, the coupling between the molecules can lead to both constructive and destructive quantum interferences. We also examine the inability of the classical Kirchhoff's superposition law to account for electron flow in multilinker GOF nanonetworks.

  19. Transport properties of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L. [Georgia Inst. of Technology, Atlanta, GA (United States)

    1995-08-01

    This project involves experimental and modeling investigation of the transport properties of chemical vapor infiltration (CVI) preforms and densified composites, with particular emphasis on gas permeability and mass diffusivity. The results of this work will be useful both for on-going CVI process development and for evaluation and optimization of composite materials for fossil energy applications. With preforms made with 500 filaments/tow Nicalon at 40 vol% fiber loading, permeability values are similar for square-weave cloth layup and 3-D weave at low density. At greater densification the 3-D weave permeability is lower and approaches zero with significantly more closed porosity than the cloth layup. For filament wound preforms we were unable to make reliable measurements with the available materials. A model for gas transport in these materials utilizes percolation theory concepts. The ultimate achievable density is related to the closing of a continuous gas path through the preform. As the density approaches this limit the gas permeability and diffusivity vanish exponentially. The value of this limit is controlled primarily by the preform fiber architecture. The observed difference between the cloth layup and 3-D weave materials is due to the larger pores at tow crossing points found in the 3-D weave.

  20. Transport properties of alumina nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Kau-Fui Vincent; Kurma, Tarun [Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL 33124 (United States)], E-mail: kwong@miami.edu

    2008-08-27

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 deg. C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m{sup -1} K{sup -1} was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 deg. C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were

  1. Transport properties of alumina nanofluids.

    Science.gov (United States)

    Wong, Kau-Fui Vincent; Kurma, Tarun

    2008-08-27

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 °C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m(-1) K(-1) was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 °C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at

  2. The Transport Properties of Activated Carbon Fibers

    Science.gov (United States)

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  3. Nanofluidics thermodynamic and transport properties

    CERN Document Server

    Michaelides, Efstathios E (Stathis)

    2014-01-01

    This volume offers a comprehensive examination of the subject of heat and mass transfer with nanofluids as well as a critical review of the past and recent research projects in this area. Emphasis is placed on the fundamentals of the transport processes using particle-fluid suspensions, such as nanofluids. The nanofluid research is examined and presented in a holistic way using a great deal of our experience with the subjects of continuum mechanics, statistical thermodynamics, and non-equilibrium thermodynamics of transport processes. Using a thorough database, the experimental, analytical, and numerical advances of recent research in nanofluids are critically examined and connected to past research with medium and fine particles as well as to functional engineering systems. Promising applications and technological issues of heat/mass transfer system design with nanofluids are also discussed. This book also: Provides a deep scientific analysis of nanofluids using classical thermodynamics and statistical therm...

  4. Transport properties of porous media from the microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Torquato, S. [Princeton Univ., NJ (United States)

    1995-12-31

    The determination of the effective transport properties of a random porous medium remains a challenging area of research because the properties depend on the microstructure in a highly complex fashion. This paper reviews recent theoretical and experimental progress that we have made on various aspects of this problem. A unified approach is taken to characterize the microstructure and the seemingly disparate properties of the medium.

  5. Technological Support of Critical Parts for Railway Transport Working Properties

    Science.gov (United States)

    Gabets, A. V.; Gabets, D. A.; Markov, A. M.; Radchenko, M. V.; Leonov, S. L.

    2017-01-01

    The materials of complex research of operational properties of a new brand cast iron CHMN-35M. Optimal chemical composition was determined. The obtained results allow to conclude about possibility of its use for the manufacture of critical parts of rolling stock of railway transport, in particular of a side bearing cap

  6. Transport properties of fully screened Kondo models

    NARCIS (Netherlands)

    Hörig, Christoph B M; Mora, Christophe; Schuricht, Dirk

    2014-01-01

    We study the nonequilibrium transport properties of fully (exactly) screened Kondo quantum dots subject to a finite bias voltage or a finite temperature. First, we calculate the Fermi-liquid coefficients of the conductance for models with arbitrary spin, i.e., its leading behavior for small bias vol

  7. Unsaturated Zone and Saturated Zone Transport Properties (U0100)

    Energy Technology Data Exchange (ETDEWEB)

    J. Conca

    2000-12-20

    This Analysis/Model Report (AMR) summarizes transport properties for the lower unsaturated zone hydrogeologic units and the saturated zone at Yucca Mountain and provides a summary of data from the Busted Butte Unsaturated Zone Transport Test (UZTT). The purpose of this report is to summarize the sorption and transport knowledge relevant to flow and transport in the units below Yucca Mountain and to provide backup documentation for the sorption parameters decided upon for each rock type. Because of the complexity of processes such as sorption, and because of the lack of direct data for many conditions that may be relevant for Yucca Mountain, data from systems outside of Yucca Mountain are also included. The data reported in this AMR will be used in Total System Performance Assessment (TSPA) calculations and as general scientific support for various Process Model Reports (PMRs) requiring knowledge of the transport properties of different materials. This report provides, but is not limited to, sorption coefficients and other relevant thermodynamic and transport properties for the radioisotopes of concern, especially neptunium (Np), plutonium (Pu), Uranium (U), technetium (Tc), iodine (I), and selenium (Se). The unsaturated-zone (UZ) transport properties in the vitric Calico Hills (CHv) are discussed, as are colloidal transport data based on the Busted Butte UZTT, the saturated tuff, and alluvium. These values were determined through expert elicitation, direct measurements, and data analysis. The transport parameters include information on interactions of the fractures and matrix. In addition, core matrix permeability data from the Busted Butte UZTT are summarized by both percent alteration and dispersion.

  8. Transport properties of inertial confinement fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Issanova, M.K.; Kodanova, S.K.; Ramazanov, T.S. [IETP, Al-Farabi Kazakh National University, Almaty (Kazakhstan); Hoffmann, D.H.H. [Institut fuer Kernphysik, Technische Universitaet Darmstadt (Germany)

    2016-06-15

    In this paper the transport properties of non-isothermal dense deuterium-tritium plasmas were studied. Based on the effective interaction potentials between particles, the Coulomb logarithm for a two-temperature nonisothermal dense plasma was obtained. These potentials take into consideration long-range multi-particle screening effects and short-range quantum-mechanical effects in two-temperature plasmas. Transport processes in such plasmas were studied using the Coulomb logarithm. The obtained results were compared with the theoretical works of other authors and with the results of molecular dynamics simulations. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Transport properties of graphene and its application

    Science.gov (United States)

    Lu, Jianming

    This thesis focuses on the transport properties of graphene, a new emerging atomically thin, two-dimensional material, with and without the application of a magnetic field. Because of its high mobility, graphene is a promising candidate for Extraordinary Magnetoresistance (EMR) devices. The magnetoresistance of an EMR device arises mainly from its geometry rather than the intrinsic response of the material itself to an applied magnetic field. As a result, the geometric parameters play an important role in its performance. Experiments employing various combinations of geometric parameters and graphene of different quality levels were conducted to determine the optimal results. We found that the optimized parameters vary for different applied magnetic fields. In a magnetic field of 9 Tesla, magnetoresistance up to 55,000% was observed. In addition, Finite Element Analysis (FEA) simulations are used to complement the experiments and explain the measured magnetoresistance. The excellent agreement between the simulations and experimental results indicates that theoretical simulation can be used as a convenient method to explore EMR devices with alternative geometries or materials. The anomalous quantum Hall effect is one of the most exciting properties of graphene. The observation of the v=0 state above a critical magnetic field is closely related to the quality of the graphene, where a higher quality reduces the critical field needed. With our high quality graphene sample, the critical field is reduced to 6.75 Tesla. Moreover, from 6.75 T to 9T, the resistance at the cross point of the metal-insulator transition (MIT) is very close to h/2e2, which resembles the case of a disordered two-dimensional electron gas (2DEG) and may indicate a similar physical mechanism. In addition to the magnetotransport measurements, the current saturation of graphene in a high electric field is studied both theoretically and experimentally. This thesis focuses primarily on bilayer graphene

  10. Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium

    Science.gov (United States)

    Hunt, J. L.; Boney, L. R.

    1973-01-01

    Equations and in computer code are presented for the thermodynamic and transport properties of gaseous, undissociated tetrafluoromethane (CF4) in chemical equilibrium. The computer code calculates the thermodynamic and transport properties of CF4 when given any two of five thermodynamic variables (entropy, temperature, volume, pressure, and enthalpy). Equilibrium thermodynamic and transport property data are tabulated and pressure-enthalpy diagrams are presented.

  11. Electronic and transport properties of kinked graphene

    DEFF Research Database (Denmark)

    Rasmussen, Jesper Toft; Gunst, Tue; Bøggild, Peter

    2013-01-01

    Local curvature, or bending, of a graphene sheet is known to increase the chemical reactivity presenting an opportunity for templated chemical functionalisation. Using first-principles calculations based on density functional theory (DFT), we investigate the reaction barrier reduction...... for the adsorption of atomic hydrogen at linear bends in graphene. We find a significant barrier lowering (≈15%) for realistic radii of curvature (≈20 Å) and that adsorption along the linear bend leads to a stable linear kink. We compute the electronic transport properties of individual and multiple kink lines......, and demonstrate how these act as efficient barriers for electron transport. In particular, two parallel kink lines form a graphene pseudo-nanoribbon structure with a semimetallic/semiconducting electronic structure closely related to the corresponding isolated ribbons; the ribbon band gap translates...

  12. Electron transport properties of cobalt doped polyaniline

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, P [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Sarkar, A [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Meikap, A K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Chattopadhyay, S K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Chatterjee, S K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Ghosh, M [Department of Physics, Ramananda College, Bishnupur, Bankura-722 122, West Bengal (India)

    2006-07-21

    Electrical transport properties of cobalt doped polyaniline in an aqueous ethanol medium were investigated in the temperature range 77 {<=} T {<=} 300 K, applying magnetic fields up to 1 T in the frequency range 20 Hz-1 MHz. The room temperature dc resistivity increases with increase in Co content. The dc resistivity and magnetoresistivity of these samples have been interpreted in terms of the variable range hopping theory. The frequency dependence of conductivity has been described by a power law {sigma}({omega}) {approx} {omega}{sup S}. The value of s is found to be temperature dependent, which shows a decreasing trend with temperature. The correlated barrier hopping model is the most likely mechanism for the electron transport. The different physical parameters were calculated from the experimental data.

  13. Transport properties of multicomponent thermal plasmas: Grad method versus Chapman-Enskog method

    Energy Technology Data Exchange (ETDEWEB)

    Porytsky, P. [Institute for Nuclear Research, 03680 Kyiv (Ukraine); Krivtsun, I.; Demchenko, V. [Paton Welding Institute, 03680 Kyiv (Ukraine); Reisgen, U.; Mokrov, O.; Zabirov, A. [RWTH Aachen University, ISF-Welding and Joining Institute, 52062 Aachen (Germany); Gorchakov, S.; Timofeev, A.; Uhrlandt, D. [Leibniz Institute for Plasma Science and Technology (INP Greifswald), 17489 Greifswald (Germany)

    2013-02-15

    Transport properties (thermal conductivity, viscosity, and electrical conductivity) for multicomponent Ar-Fe thermal plasmas at atmospheric pressure have been determined by means of two different methods. The transport coefficients set based on Grad's method is compared with the data obtained when using the Chapman-Enskog's method. Results from both applied methods are in good agreement. It is shown that the Grad method is suitable for the determination of transport properties of the thermal plasmas.

  14. Determination of potential energy functions and calculation transport properties of oxygen and nitric oxide via the inversion of reduced viscosity collision integrals at zero pressure

    Energy Technology Data Exchange (ETDEWEB)

    Abbaspour, Mohsen [Department of Chemistry, Ferdowsi University, Mashhad, Khorasan-Razavi 91779 (Iran, Islamic Republic of)], E-mail: mabbaspoor@wali.um.ac.ir; Goharshadi, Elaheh K. [Department of Chemistry, Ferdowsi University, Mashhad, Khorasan-Razavi 91779 (Iran, Islamic Republic of); Emampour, Jalal S. [Department of Chemistry, Ferdowsi University, Mashhad, Khorasan-Razavi 91779 (Iran, Islamic Republic of)

    2006-08-01

    The potential energy functions of oxygen and nitric oxide have been determined via the inversion of reduced viscosity collision integrals at zero pressure and fitted to obtain the analytical potential forms. The potentials reproduce viscosity, self-diffusion coefficient, and second virial coefficient of oxygen and nitric oxide in excellent accordance with the experimental data over a wide range of temperature. We have also derived very accurate equations for viscosity, self-diffusion coefficient, and second virial coefficient of O{sub 2} and NO at different temperatures. Comparisons of O{sub 2} -O{sub 2} potential with experimental potentials of Perugia group and ESMSV-type potential and ab initio potentials (MCRI-1/B3 and CCSD (T)/MCRI mixed model) and NO-NO potential with the recently determined potential by means of ab initio electronic structure calculations, CASSCF/CASPT2 (18/14)/6-311G(2d) have been also included.

  15. TRANSPORT PROPERTIES OF THE STRONGLY CORRELATED SYSTEMS

    Directory of Open Access Journals (Sweden)

    T.Domanski

    2004-01-01

    Full Text Available The transport properties of various systems are studied here in the context of three different models. These are: - the disordered Hubbard model applicable to correlated binary alloys with a general disorder, - the Anderson model used in describing the Kondo physics of a quantum dot connected to the external superconducting leads, and - the Ranninger-Robaszkiewicz model applied to the study of optical properties of the system with preformed electron pairs above the temperature of transition to the superconducting state. We calculate the density of states, specific heat, the Wilson ratio and conductivity of the correlated binary alloy with off-diagonal disorder. We investigate the conditions under which the Kondo peak appears in the density of states and in the conductance of a dot coupled to the external superconducting leads. We analyze the effect of the pseudogap on the optical spectra in the high temperature superconductors described by the boson-fermion model.

  16. A general method for determining secondary active transporter substrate stoichiometry.

    Science.gov (United States)

    Fitzgerald, Gabriel A; Mulligan, Christopher; Mindell, Joseph A

    2017-01-25

    The number of ions required to drive substrate transport through a secondary active transporter determines the protein's ability to create a substrate gradient, a feature essential to its physiological function, and places fundamental constraints on the transporter's mechanism. Stoichiometry is known for a wide array of mammalian transporters, but, due to a lack of readily available tools, not for most of the prokaryotic transporters for which high-resolution structures are available. Here, we describe a general method for using radiolabeled substrate flux assays to determine coupling stoichiometries of electrogenic secondary active transporters reconstituted in proteoliposomes by measuring transporter equilibrium potentials. We demonstrate the utility of this method by determining the coupling stoichiometry of VcINDY, a bacterial Na(+)-coupled succinate transporter, and further validate it by confirming the coupling stoichiometry of vSGLT, a bacterial sugar transporter. This robust thermodynamic method should be especially useful in probing the mechanisms of transporters with available structures.

  17. Modeling transport properties of inhomogeneous superconductor-metal composites

    Energy Technology Data Exchange (ETDEWEB)

    Borroto, A.; Altshuler, E., E-mail: ealtshuler@fisica.uh.cu [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Del Río, L. [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Physics Department, McGill University, Montreal, Quebec H3A 2T8 (Canada); Arronte, M. [BRALAX, S. de RL., Tampico, Tamaulipas (Mexico); Technological Laser Laboratory, IMRE, University of Havana, 10400 Havana (Cuba); Johansen, T. H. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo (Norway); Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2014-11-17

    We propose a model for a superconductor-metal composite that allows to derive intrinsic transport properties of the superconducting phase based on 2D images of its cross section, and a minimal set of parameters. The method is tested experimentally by using, as model composite, a “transversal bridge” made on a Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} (BSCCO)-Ag multi-filamentary tape. It is shown that the approach allows to predict the measured I−〈E〉 curves of the filaments. In addition, one can determine the critical current anisotropy between the longitudinal and transverse directions of the Ag-BSCCO tape, and also of its superconducting filaments separately, which emphasizes the role of the morphology of the composite in the transport properties.

  18. Electronic transport properties of (fluorinated) metal phthalocyanine

    KAUST Repository

    Fadlallah, M M

    2015-12-21

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S–Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  19. Electronic transport properties of phenylacetylene molecular junctions

    Institute of Scientific and Technical Information of China (English)

    Liu Wen; Cheng Jie; Yah Cui-Xia; Li Hai-Hong; Wang Yong-Juan; Liu De-Sheng

    2011-01-01

    Electronic transport properties of a kind of phenylacetylene compound- (4-mercaptophenyl)-phenylacetylene are calculated by the first-principles method in the framework of density functional theory and the nonequilibrium Green's function formalism.The molecular junction shows an obvious rectifying behaviour at a bias voltage larger than 1.0 V.The rectification effect is attributed to the asymmetry of the interface contacts.Moreover,at a bias voltage larger than 2.0 V,which is not referred to in a relevant experiment [Fang L,Park J Y,Ma H,Jan A K Y and Salmeron M 2007 Langmuir 23 11522],we find a negative differential resistance phenomenon.The negative differential resistance effect may originate from the change of the delocalization degree of the molecular orbitais induced by the bias.

  20. Transport Properties of the Universal Quantum Equation

    Institute of Scientific and Technical Information of China (English)

    A.I.Arbab

    2012-01-01

    The universal quantum equation (UQE) is found to describe the transport properties of the quantum particles.This equation describes a wave equation interacting with constant scalar and vector potentials propagating in spacetime.A new transformation that sends the Schr(o)dinger equation with a potential energy V =-1/2mc2 to Dirac's equation is proposed.The Cattaneo telegraph equation as well as a one-dimensional UQE are compatible with our recently proposed generalized continuity equations.Furthermore,a new wave equation resulted from the invariance of the UQE under the post-Galilean transformations is derived.This equation is found to govern a Klein Gordon's particle interacting with a photon-like vector field (ether) whose magnitude is proportional to the particle's mass.

  1. Physical transport properties of marine microplastic pollution

    Directory of Open Access Journals (Sweden)

    A. Ballent

    2012-12-01

    Full Text Available Given the complexity of quantitative collection, knowledge of the distribution of microplastic pollution in many regions of the world ocean is patchy, both spatially and temporally, especially for the subsurface environment. However, with knowledge of typical hydrodynamic behavior of waste plastic material, models predicting the dispersal of pelagic and benthic plastics from land sources into the ocean are possible. Here we investigate three aspects of plastic distribution and transport in European waters. Firstly, we assess patterns in the distribution of plastics found in fluvial strandlines of the North Sea and how distribution may be related to flow velocities and distance from source. Second, we model transport of non-buoyant preproduction pellets in the Nazaré Canyon of Portugal using the MOHID system after assessing the density, settling velocity, critical and depositional shear stress characteristics of such waste plastics. Thirdly, we investigate the effect of surface turbulences and high pressures on a range of marine plastic debris categories (various densities, degradation states and shapes tested in an experimental water column simulator tank and pressure laboratory. Plastics deposited on North Sea strandlines varied greatly spatially, as a function of material composition and distance from source. Model outputs indicated that such dense production pellets are likely transported up and down canyon as a function of tidal forces, with only very minor net down canyon movement. Behaviour of plastic fragments under turbulence varied greatly, with the dimensions of the material, as well as density, playing major determining roles. Pressure was shown to affect hydrodynamic behaviours of only low density foam plastics at pressures ≥ 60 bar.

  2. Physical transport properties of marine microplastic pollution

    Science.gov (United States)

    Ballent, A.; Purser, A.; Mendes, P. de Jesus; Pando, S.; Thomsen, L.

    2012-12-01

    Given the complexity of quantitative collection, knowledge of the distribution of microplastic pollution in many regions of the world ocean is patchy, both spatially and temporally, especially for the subsurface environment. However, with knowledge of typical hydrodynamic behavior of waste plastic material, models predicting the dispersal of pelagic and benthic plastics from land sources into the ocean are possible. Here we investigate three aspects of plastic distribution and transport in European waters. Firstly, we assess patterns in the distribution of plastics found in fluvial strandlines of the North Sea and how distribution may be related to flow velocities and distance from source. Second, we model transport of non-buoyant preproduction pellets in the Nazaré Canyon of Portugal using the MOHID system after assessing the density, settling velocity, critical and depositional shear stress characteristics of such waste plastics. Thirdly, we investigate the effect of surface turbulences and high pressures on a range of marine plastic debris categories (various densities, degradation states and shapes tested) in an experimental water column simulator tank and pressure laboratory. Plastics deposited on North Sea strandlines varied greatly spatially, as a function of material composition and distance from source. Model outputs indicated that such dense production pellets are likely transported up and down canyon as a function of tidal forces, with only very minor net down canyon movement. Behaviour of plastic fragments under turbulence varied greatly, with the dimensions of the material, as well as density, playing major determining roles. Pressure was shown to affect hydrodynamic behaviours of only low density foam plastics at pressures ≥ 60 bar.

  3. Transport properties of supercooled confined water

    Science.gov (United States)

    Mallamace, F.; Branca, C.; Broccio, M.; Corsaro, C.; Gonzalez-Segredo, N.; Spooren, J.; Stanley, H. E.; Chen, S.-H.

    2008-07-01

    This article presents an overview of recent experiments performed on transport properties of water in the deeply supercooled region, a temperature region of fundamental importance in the science of water. We report data of nuclear magnetic resonance, quasi-elastic neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy, studying water confined in nanometer-scale environments. When contained within small pores, water does not crystallise, and can be supercooled well below its homogeneous nucleation temperature Th. On this basis it is possible to carry out a careful analysis of the well known thermodynamical anomalies of water. Studying the temperature and pressure dependencies of water dynamics, we show that the liquid-liquid phase transition (LLPT) hypothesis represents a reliable model for describing liquid water. In this model, water in the liquid state is a mixture of two different local structures, characterised by different densities, namely the low density liquid (LDL) and the high-density liquid (HDL). The LLPT line should terminate at a special transition point: a low-T liquid-liquid critical point. We discuss the following experimental findings on liquid water: (i) a crossover from non-Arrhenius behaviour at high T to Arrhenius behaviour at low T in transport parameters; (ii) a breakdown of the Stokes-Einstein relation; (iii) the existence of a Widom line, which is the locus of points corresponding to maximum correlation length in the p-T phase diagram and which ends in the liquid-liquid critical point; (iv) the direct observation of the LDL phase; (v) a minimum in the density at approximately 70 K below the temperature of the density maximum. In our opinion these results represent the experimental proofs of the validity of the LLPT hypothesis.

  4. Transport properties of ruthenophanes - A theoretical insight

    Science.gov (United States)

    Garcia, Leone C.; Caramori, Giovanni F.; Bergamo, Pedro A. S.; Parreira, Renato L. T.

    2016-10-01

    In this article, the electron transport properties of a series of ruthenophanes, 1-4, containing electron-donor and electron-acceptor substituents are studied. The electronic transmission at zero bias is mainly driven by only one eigenchannel. The substitutions constrain the energies in which the probability of electronic transmission is significant. The results suggest that the conductance at zero bias is dependent on the nature of the employed substituent. The eigenchannel wave functions show that the central molecules are preferentially coupled with right electrode. The calculated molecular projected self-consistent hamiltonian states also suggest that there is a dependence of the conductance at zero bias with the nature of the employed substituent. The current-voltage analyses suggest that the negative differential resistance effect is present in ruthenophanes, but it is dependent on both the nature of the substituent and the bias. Despite the moderate rectification ratio of the ruthenophanes, they present non-ohmic behaviour, indicating that they can be used as potential candidates in electronic molecular devices such as switches, oscillators, and frequency multipliers.

  5. Low temperature carrier transport properties in isotopically controlled germanium

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, K.

    1994-12-01

    Investigations of electronic and optical properties of semiconductors often require specimens with extremely homogeneous dopant distributions and precisely controlled net-carrier concentrations and compensation ratios. The previous difficulties in fabricating such samples are overcome as reported in this thesis by growing high-purity Ge single crystals of controlled {sup 75}Ge and {sup 70}Ge isotopic compositions, and doping these crystals by the neutron transmutation doping (NTD) technique. The resulting net-impurity concentrations and the compensation ratios are precisely determined by the thermal neutron fluence and the [{sup 74}Ge]/[{sup 70}Ge] ratios of the starting Ge materials, respectively. This method also guarantees unprecedented doping uniformity. Using such samples the authors have conducted four types of electron (hole) transport studies probing the nature of (1) free carrier scattering by neutral impurities, (2) free carrier scattering by ionized impurities, (3) low temperature hopping conduction, and (4) free carrier transport in samples close to the metal-insulator transition.

  6. Geometry dependent transport properties of undoped InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Guenel, H. Yusuf; Bloemers, Christian; Sladek, Kamil; Penz, Andreas; Hardtdegen, Hilde; Lenk, Steffi; Schubert, Juergen; Schaepers, Thomas; Gruetzmacher, Detlev [Institute of Bio- and Nanosystems (IBN-1) and JARA-Fundamentals of Future Information Technology, Research Centre Juelich GmbH, 52425 Juelich (Germany); Luysberg, Martina [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forchungszentrum Juelich, 52425 Juelich (Germany)

    2010-07-01

    In recent time nanowire (NW) structures attracted much attention, for electronics, optoelectronics and fundamental quantum properties. On account of different application purposes basic transport properties are crucially important at room temperature as well as low temperatures. In this respect InAs NWs are particularly important due to the low band gap and high carrier concentration. We characterized the basic transport parameters of undoped InAs NWs at room temperature, which were grown on GaAs(001) substrate by MOVPE without catalyst. The NWs that we used in this work had diameters ranging from 25 nm to 200 nm and lengths up to 3.5 {mu}m. Basic transport parameters, such as carrier concentration and mobility, were determined by using two- and four-terminal measurement configuration. The carrier concentration could be controlled by a SiO{sub 2} -isolated back-gate structure. By analyzing the transfer characteristics of the NW FET, we observed very good gate controllability.

  7. Transport properties of doped BICUVOX ceramics

    Directory of Open Access Journals (Sweden)

    Yaremchenko, A. A.

    1999-12-01

    Full Text Available Polycrystalline Bi2-xLaxV0.90Cu0.10O5.5-δ (x = 0, 0.10 and 0.20 and Bi1.90Pr0.10V0.90Cu0.10O5.5-δ were prepared by the standard ceramic- synthesis technique. The total electrical conductivity of Bi1.90La0.10V0.90Cu0.10O5.5-δ at temperatures above 500 K is slightly lower than undoped BICUVOX.10, but transport properties in the temperature range 370 - 450 K are similar. Doping BICUVOX. 10 with praseodymium led to the formation of impurity phases, and to both lower conductivity and thermal expansion of ceramic samples. Oxygen-ion transference numbers of phases with moderate rare-earth dopant content (x ≤ 0.10 vary in the range 0.90 - 0.99 at 780 - 910 K and decrease with increasing temperature. Thermal expansion coefficients calculated from the dilatometric data for Bi2-xLnxV0.90Cu0.10O5.5-δ ceramics are (16.1 - 18.0 x 10-6 K-1 at 730 - 1050 K.

    Bi2-xLaxV0.90Cu0.10O5.5-δ (x = 0, 0.10 and 0.20 y Bi1.90Pr0.10V0.90Cu0.10O5.5-δ policristalinos fueron preparados por síntesis cerámica convencional. La conductividad eléctrica total de Bi2-xLaxV0.90Cu0.10O5.5-δ a temperaturas superiores a 500K es ligeramente menor que la correspondiente a BICUVOX.10 no dopada, pero las propiedades de transporte en el rango de temperaturas 370- 450K son similares. Dopando BICUVOX.10 con praseodimio produce la formación de fases secundarias y la reducción de la conductividad y la expansión térmica de las muestras cerámicas. El número de transporte del ión sin oxígeno de fases con un contenido en tierra rara moderado como dopante (x ≤ 0.10 varía en el rango 0.90-0.99 a 780-910k y disminuye con el aumento de la temperatura. Los coeficientes de expansión térmicos calculados a partir de los datos dilatométricos para cerámicas Bi2-xLnxV0.90Cu0.10O5.5-δ son (16.1 - 18.0 x 10-6 K-1 a 730 - 1050 K.

  8. A general method for determining secondary active transporter substrate stoichiometry

    Science.gov (United States)

    Fitzgerald, Gabriel A; Mulligan, Christopher; Mindell, Joseph A

    2017-01-01

    The number of ions required to drive substrate transport through a secondary active transporter determines the protein’s ability to create a substrate gradient, a feature essential to its physiological function, and places fundamental constraints on the transporter’s mechanism. Stoichiometry is known for a wide array of mammalian transporters, but, due to a lack of readily available tools, not for most of the prokaryotic transporters for which high-resolution structures are available. Here, we describe a general method for using radiolabeled substrate flux assays to determine coupling stoichiometries of electrogenic secondary active transporters reconstituted in proteoliposomes by measuring transporter equilibrium potentials. We demonstrate the utility of this method by determining the coupling stoichiometry of VcINDY, a bacterial Na+-coupled succinate transporter, and further validate it by confirming the coupling stoichiometry of vSGLT, a bacterial sugar transporter. This robust thermodynamic method should be especially useful in probing the mechanisms of transporters with available structures. DOI: http://dx.doi.org/10.7554/eLife.21016.001 PMID:28121290

  9. 30 CFR 206.262 - Determination of transportation allowances.

    Science.gov (United States)

    2010-07-01

    ... REVENUE MANAGEMENT PRODUCT VALUATION Federal Coal § 206.262 Determination of transportation allowances. (a... transporting the coal under that contract, subject to monitoring, review, audit, and possible future adjustment... are generally those for depreciable fixed assets (including costs of delivery and installation...

  10. Electronic, transport, and magnetic properties of punctured carbon nanotubes

    Science.gov (United States)

    dos Santos, Jeová Calisto; de Vasconcelos, Fabrício Morais; de Aguiar, Acrísio Lins; Alves, Tayroni Francisco de Alencar; Meunier, Vincent; Girão, Eduardo Costa

    2016-12-01

    We use a spin-polarized tight-binding model Hamiltonian and the Landauer transport formalism to investigate the electronic transport properties of carbon nanotubes where different types of holes have been drilled through their sidewalls. We focus on zigzag edged defects with different atomic configurations since these systems enable the emergence of magnetic properties. We show that a number of hole geometries, magnetic states, and electronic spins yield attractive transport properties, such as ON/OFF switching for the electronic current, and nontrivial dependence of transmission with hole size.

  11. determination of physio determination of physio-chemical properties ...

    African Journals Online (AJOL)

    eobe

    The objectives were to determine the physical, chemical ... seed oil exhibited good chemical properties for biodiesel production with a viscosity of 46.58mpa/s at 30oC,. Free Fatty Acid (FFA) ... production than animal fats and used/blended oils.

  12. Transport properties site descriptive model. Guidelines for evaluation and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berglund, Sten [WSP Environmental, Stockholm (Sweden); Selroos, Jan-Olof [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2004-04-01

    This report describes a strategy for the development of Transport Properties Site Descriptive Models within the SKB Site Investigation programme. Similar reports have been produced for the other disciplines in the site descriptive modelling (Geology, Hydrogeology, Hydrogeochemistry, Rock mechanics, Thermal properties, and Surface ecosystems). These reports are intended to guide the site descriptive modelling, but also to provide the authorities with an overview of modelling work that will be performed. The site descriptive modelling of transport properties is presented in this report and in the associated 'Strategy for the use of laboratory methods in the site investigations programme for the transport properties of the rock', which describes laboratory measurements and data evaluations. Specifically, the objectives of the present report are to: Present a description that gives an overview of the strategy for developing Site Descriptive Models, and which sets the transport modelling into this general context. Provide a structure for developing Transport Properties Site Descriptive Models that facilitates efficient modelling and comparisons between different sites. Provide guidelines on specific modelling issues where methodological consistency is judged to be of special importance, or where there is no general consensus on the modelling approach. The objectives of the site descriptive modelling process and the resulting Transport Properties Site Descriptive Models are to: Provide transport parameters for Safety Assessment. Describe the geoscientific basis for the transport model, including the qualitative and quantitative data that are of importance for the assessment of uncertainties and confidence in the transport description, and for the understanding of the processes at the sites. Provide transport parameters for use within other discipline-specific programmes. Contribute to the integrated evaluation of the investigated sites. The site descriptive

  13. Transport Properties of some Conducting TCNQ-Salts

    DEFF Research Database (Denmark)

    Mortensen, Kell; Jacobsen, C. S.; Andersen, J. R.

    1979-01-01

    An experimental decomposition of the transport properties for organic transfer salts is attempted on the basis of conductivity and thermopower measurements. A decomposition is proposed on the compound: TMTSF-DMTCNQ. Furthermore some new transport data on the organic low-temperature conductor: HMT...

  14. Computer program for calculating thermodynamic and transport properties of fluids

    Science.gov (United States)

    Hendricks, R. C.; Braon, A. K.; Peller, I. C.

    1975-01-01

    Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.

  15. Molecular properties of bacterial multidrug transporters

    NARCIS (Netherlands)

    Putman, M; van Veen, HW; Konings, WN

    2000-01-01

    One of the mechanisms that bacteria utilize to evade the toxic effects of antibiotics is the active extrusion of structurally unrelated drugs from the cell. Both intrinsic and acquired multidrug transporters play an important role in antibiotic resistance of several pathogens, including Neisseria go

  16. The effect of mucolytic agents on the rheologic and transport properties of canine tracheal mucus.

    Science.gov (United States)

    Martin, R; Litt, M; Marriott, C

    1980-03-01

    The effect of several sulfhydryl and other agents on the rheologic and mucociliary transport properties of a model secretion, reconstituted canine tracheal mucus, was investigated. The mucus was obtained via the canine tracheal pouch. Rheologic properties were determined by mirorheometry, and the ciliary transport rate was determined using the frog palate technique. It was found that N-acetyl cysteine decreased the elastic modulus, leading to improved mucociliary transport at concentrations such that the mucin did not precipitate. S-carboxymethyl cysteine had no effect on either mucus properties or mucociliary transport rate, and its reported effectiveness in vivo must be due to some mechanism other than solubilization of mucin. Similar results were found with other blocked sulfhydryl compounds. Urea and potassium iodide to decrease mucus elasticity, but are harmful to cilia at the concentrations needed.

  17. Transport properties of highly asymmetric hard-sphere mixtures.

    Science.gov (United States)

    Bannerman, Marcus N; Lue, Leo

    2009-04-28

    The static and dynamic properties of binary mixtures of hard spheres with a diameter ratio of sigma(B)/sigma(A)=0.1 and a mass ratio of m(B)/m(A)=0.001 are investigated using event driven molecular dynamics. The contact values of the pair correlation functions are found to compare favorably with recently proposed theoretical expressions. The transport coefficients of the mixture, determined from simulation, are compared to the predictions of the revised Enskog theory using both a third-order Sonine expansion and direct simulation Monte Carlo. Overall, the Enskog theory provides a fairly good description of the simulation data, with the exception of systems at the smallest mole fraction of larger spheres (x(A)=0.01) examined. A "fines effect" was observed at higher packing fractions, where adding smaller spheres to a system of large spheres decreases the viscosity of the mixture; this effect is not captured by the Enskog theory.

  18. Dielectric Properties Determination of a Stratified Medium

    Directory of Open Access Journals (Sweden)

    P. Yoiyod

    2015-04-01

    Full Text Available The method of detection of variation in dielectric properties of a material covered with another material, which requires nondestructive measurement, has numerous applications and the accurate measurement system is desirable. This paper presents a dielectric properties determination technique whereby the dielectric constant and loss factor are extracted from the measured reflection coefficient. The high frequency reflection coefficient shows the effect of the upper layer, while the dielectric properties of the lower layer can be determined at the lower frequency. The proposed technique is illustrated in 1-11 GHz band using 5 mm-thick water and 5% saline solution. The fluctuation of the dielectric properties between the high frequency and the low frequency, results from the edge diffraction in the material and the multiple reflections at the boundary of the two media, are invalid results. With the proposed technique, the dielectric properties of the lower layer can be accurately determined. The system is validated by measurement and good agreement is obtained at the frequency below 3.5 GHz. It can be applied for justifying variation of the material in the lower layer which is important in industrial process.

  19. Transport properties of nanoperforated Nb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Trezza, M., E-mail: trezza@sa.infn.i [Laboratorio Regionale SuperMat, CNR-INFM Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Baronissi I-84081 (Italy); Cirillo, C. [Laboratorio Regionale SuperMat, CNR-INFM Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Baronissi (Saudi Arabia) I-84081 (Italy); Prischepa, S.L. [State University of Informatics and RadioElectronics, P. Brovka Street 6, Minsk 220013 (Belarus); Attanasio, C. [Laboratorio Regionale SuperMat, CNR-INFM Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Baronissi I-84081 (Italy)

    2010-10-01

    Porous silicon, obtained by electrochemical etching, has been used as a substrate for the growth of nanoperforated Nb thin films. The films, deposited by UHV magnetron sputtering, inherited from the Si substrates their structure, made of holes of 10 nm diameter and of 20 and 40 nm spacing, which provide an artificial pinning lattice. Commensurability effects between the Abrikosov vortex lattice and the artificial array of holes were investigated by transport measurements.

  20. Fibonacci Identities via the Determinant Sum Property

    Science.gov (United States)

    Spivey, Michael

    2006-01-01

    We use the sum property for determinants of matrices to give a three-stage proof of an identity involving Fibonacci numbers. Cassini's and d'Ocagne's Fibonacci identities are obtained at the ends of stages one and two, respectively. Catalan's Fibonacci identity is also a special case.

  1. Electronic transport properties of copper and gold at atomic scale

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadzadeh, Saeideh

    2010-11-23

    The factors governing electronic transport properties of copper and gold atomic-size contacts are theoretically examined in the present work. A two-terminal conductor using crystalline electrodes is adopted. The non-equilibrium Green's function combined with the density functional tight-binding method is employed via gDFTB simulation tool to calculate the transport at both equilibrium and non-equilibrium conditions. The crystalline orientation, length, and arrangement of electrodes have very weak influence on the electronic characteristics of the considered atomic wires. The wire width is found to be the most effective geometric aspect determining the number of conduction channels. The obtained conductance oscillation and linear current-voltage curves are interpreted. To analyze the conduction mechanism in detail, the transmission channels and their decomposition to the atomic orbitals are calculated in copper and gold single point contacts. The presented results offer a possible explanation for the relation between conduction and geometric structure. Furthermore, the results are in good agreement with available experimental and theoretical studies. (orig.)

  2. Statistical properties of transport in plasma turbulence

    DEFF Research Database (Denmark)

    Naulin, V.; Garcia, O.E.; Nielsen, A.H.;

    2004-01-01

    The statistical properties of the particle flux in different types of plasma turbulence models are numerically investigated using probability distribution functions (PDFs). The physics included in the models range from two-dimensional drift wave turbulence to three-dimensional MHD dynamics...

  3. Visualization of Steady-State Ionic Concentration Profiles Formed in Electrolytes during Li-Ion Battery Operation and Determination of Mass-Transport Properties by in Situ Magnetic Resonance Imaging.

    Science.gov (United States)

    Krachkovskiy, Sergey A; Bazak, J David; Werhun, Peter; Balcom, Bruce J; Halalay, Ion C; Goward, Gillian R

    2016-06-29

    Accurate modeling of Li-ion batteries performance, particularly during the transient conditions experienced in automotive applications, requires knowledge of electrolyte transport properties (ionic conductivity κ, salt diffusivity D, and lithium ion transference number t(+)) over a wide range of salt concentrations and temperatures. While specific conductivity data can be easily obtained with modern computerized instrumentation, this is not the case for D and t(+). A combination of NMR and MRI techniques was used to solve the problem. The main advantage of such an approach over classical electrochemical methods is its ability to provide spatially resolved details regarding the chemical and dynamic features of charged species in solution, hence the ability to present a more accurate characterization of processes in an electrolyte under operational conditions. We demonstrate herein data on ion transport properties (D and t(+)) of concentrated LiPF6 solutions in a binary ethylene carbonate (EC)-dimethyl carbonate (DMC) 1:1 v/v solvent mixture, obtained by the proposed technique. The buildup of steady-state (time-invariant) ion concentration profiles during galvanostatic experiments with graphite-lithium metal cells containing the electrolyte was monitored by pure phase-encoding single point imaging MRI. We then derived the salt diffusivity and Li(+) transference number over the salt concentration range 0.78-1.27 M from a pseudo-3D combined PFG-NMR and MRI technique. The results obtained with our novel methodology agree with those obtained by electrochemical methods, but in contrast to them, the concentration dependences of salt diffusivity and Li(+) transference number were obtained simultaneously within the single in situ experiment.

  4. Magnetothermoelectric transport properties of multiterminal graphene nanoribbons

    Science.gov (United States)

    Wei, Miao-Miao; Zhang, Ying-Tao; Guo, Ai-Min; Liu, Jian-Jun; Xing, Yanxia; Sun, Qing-Feng

    2016-06-01

    The Peltier effect and the Ettingshausen effect are investigated in graphene nanoribbons, where charge current produces heat current along the longitudinal direction in the former case, and longitudinal charge current generates transverse heat current in the latter case. With the aid of the nonequilibrium Green's function and the Landauer-Büttiker formalism, the Peltier coefficient Πc and the Ettingshausen coefficient Ec are obtained. We found that the Kelvin relation is always valid for the longitudinal thermoelectric transport, i.e., Πc=T Sc , with T the temperature and Sc the Seebeck coefficient. In contrast, for transverse magnetothermoelectric transport, the Kelvin relation breaks down and Ec≠T Nc usually, with Nc the Nernst coefficient. In the region of weak magnetic field, the Ettingshausen effect depends strongly on device parameters. When the Fermi energy EF is close to the Dirac point, the Ettingshausen effect of the semiconducting armchair graphene nanoribbon is much stronger than that of the metallic one. When EF is far away from the Dirac point, the Ettingshausen coefficient Ec oscillates around zero. When under a strong magnetic field, Ec is independent of the device parameters and swells only near the Dirac point. Further, the dependence of Ec on EF can be scaled by EF/kBT , with a peak value of (2 ln2 ) kBT /e for the three-terminal system and (4/3 ln2 ) kBT /e for the four-terminal system. We also study the impact of disorder on the Ettingshausen effect. Regardless of the magnetic field strength, Ec is robust against moderate disorder scattering. In addition, in the strong magnetic field, Ec with additional regular oscillating structure can be caused by disorder.

  5. Observationally Determining the Properties of Dark Matter

    CERN Document Server

    Hu, W; Tegmark, M; White, M; Hu, Wayne; Eisenstein, Daniel J.; Tegmark, Max; White, Martin

    1999-01-01

    Determining the properties of the dark components of the universe remains one of the outstanding challenges in cosmology. We explore how upcoming CMB anisotropy measurements, galaxy power spectrum data, and supernova (SN) distance measurements can observationally constrain their gravitational properties with minimal assumptions on the theoretical side. SN observations currently suggest the existence of dark matter with an exotic equation of state p/rho -1/2, then the clustering behavior (sound speed) of the dark component can be determined so as to test the scalar-field ``quintessence'' hypothesis. If the exotic matter turns out instead to be simply a cosmological constant (p/rho = -1), the combination of CMB and galaxy survey data should provide a significant detection of the remaining dark matter, the neutrino background radiation (NBR). The gross effect of its density or temperature on the expansion rate is ill-constrained as it is can be mimicked by a change in the matter density. However, anisotropies o...

  6. Methylxanthines: properties and determination in various objects

    Science.gov (United States)

    Andreeva, Elena Yu; Dmitrienko, Stanislava G.; Zolotov, Yurii A.

    2012-05-01

    Published data on the properties and determination of caffeine, theophylline, theobromine and some other methylxanthines in various objects are surveyed and described systematically. Different sample preparation procedures such as liquid extraction from solid matrices and liquid-liquid, supercritical fluid and solid-phase extraction are compared. The key methods of analysis including chromatography, electrophoresis, spectrometry and electrochemical methods are discussed. Examples of methylxanthine determination in plants, food products, energy beverages, pharmaceuticals, biological fluids and natural and waste waters are given. The bibliography includes 393 references.

  7. Material simulation of charge carrier transport properties of polymer dielectrics

    Science.gov (United States)

    Unge, Mikael; Christen, Thomas; Törnkvist, Christer; ABB Corporate Research Team

    To understand electron and hole transport in solid material requires to know its electronic properties, i.e. the density of states (DOS) and whether the states are spatially localized or delocalized. The states closest to the band edges may be localized, states further away can be delocalized. This transition from localized to delocalized states determines the mobility edge, above the mobility edge the mobility is expected to be high. A real polymer is never perfect; it contains a number of oxidative states, bonding defects and molecular impurities. These imperfections yield electronic states that can appear in the band gap of the polymer, traps. Traps can be shallow, i.e. close to the band edges, from these states the charge carrier easily can jump to a state in the band edge or another shallow state. Other traps can be deep, in these states it is likely that the charge carrier remains and become immobile. All these properties related to the electronic structure of the polymer, including its defects, affects the conductivity of the polymer. Linear scaling Density Functional Theory has been applied to calculate electronic structure of amorphous polyethylene. In particular DOS, trap levels and mobility edges are studied.

  8. 30 CFR 206.110 - How do I determine a transportation allowance under an arm's-length transportation contract?

    Science.gov (United States)

    2010-07-01

    ... under an arm's-length transportation contract? 206.110 Section 206.110 Mineral Resources MINERALS... § 206.110 How do I determine a transportation allowance under an arm's-length transportation contract? (a) If you or your affiliate incur transportation costs under an arm's-length transportation...

  9. Conical nanopore membranes. Preparation and transport properties.

    Science.gov (United States)

    Li, Naichao; Yu, Shufang; Harrell, C Chad; Martin, Charles R

    2004-04-01

    We have been investigating applications of nanopore membranes in analytical chemistry-specifically in membrane-based bioseparations, in electroanalytical chemistry, and in the development of new approaches to biosensor design. Membranes that have conically shaped pores (as opposed to the more conventional cylindrical shape) may offer some advantages for these applications. We describe here a simple plasma-etch method that converts cylindrical nanopores in track-etched polymeric membranes into conically shaped pores. This method allows for control of the shape of the resulting conical nanopores. For example, the plasma-etched pores may be cylindrical through most of the membrane thickness blossoming into cones at one face of the membrane (trumpet-shaped), or they may be nearly perfect cones. The key advantage of the conical pore shape is a dramatic enhancement in the rate of transport through the membrane, relative to an analogous cylindrical pore membrane. We demonstrate this here by measuring the ionic resistances of the plasma-etched conical pore membranes.

  10. Transport properties of colossal magnetoresistive materials

    CERN Document Server

    Yates, K A

    2002-01-01

    A microwave technique was developed in order to test the validity of the hypothesis that the microwave transport of polycrystalline, optimally doped, colossal magnetoresistive materials was dominated by intragranular material. The microwave surface resistance at 9GHz was compared with dc resistivity and magnetisation to study the influence of yttrium doping on the grain boundary regions of bulk polycrystalline samples of La sub 0 sub . sub 7 sub - sub x Y sub x Ca sub 0 sub . sub 3 MnO sub 3. It was found that, within the grains, the addition of yttrium causes the activation energy above T sub p to increase. A phenomenological model was introduced to explain the data in terms of the difference in structure between the grain and grain boundary regions. The technique was also used to study the influence of deoxygenation on the grain boundary regions of bulk, polycrystalline, La sub 0 sub . sub 6 sub 7 Ca sub 0 sub . sub 3 sub 3 MnO sub 3. For samples interconnected porosity, low temperature (600 deg C), short a...

  11. Transport properties of a novel molecular rotor

    Science.gov (United States)

    Xue, Mei; Wang, K. L.; Kabehie, Sanaz; Zink, Jeffrey I.

    2008-03-01

    Rotary motion around a molecular axis has been controlled by electron transfer process and by photoexcitation. The basis of the motion is intramolecular rotation of a ligand (3,8-di-ethynyltrityl-1, 10-phenanthroline) around a copper axle. The asymmetric copper system is synthesized by immobilizing a ``stator'' to a silicon support. The ``rotator,'' 3,8-di-ethynyltrityl-1, 10-phenanthroline is complexed to the metal center, Cu (I) or Cu (II) serving as an ``axle''. The Cu (I) system structure is tetrahedral, but that of Cu (II) is square planar. The interconversion of the two provides the basis for controlled, rotational motion. Hysteresis is observed in the different region of the applied voltage for different stators. The peak of the bisP-Si shifts to the left compared to that of the phen-Si stator because of the larger energy gap of phen-Si. The energy states of the Cu (I) and Cu (II) are extracted from the transport measurement results.

  12. 30 CFR 206.57 - Determination of transportation allowances.

    Science.gov (United States)

    2010-07-01

    ... lessee may elect to use either a straight-line depreciation method based on the life of equipment or on... cost allocation method on the basis of the values of the products transported. MMS shall approve the method unless it determines that it is not consistent with the purposes of the regulations in this...

  13. Industrial Requirements for Thermodynamics and Transport Properties

    DEFF Research Database (Denmark)

    Hendriks, Eric; Kontogeorgis, Georgios; Dohrn, Ralf

    2010-01-01

    . The main results are as follows. There is (still) an acute need for accurate, reliable, and thermodynamically consistent experimental data. Quality is more important than quantity. Similarly, there is a great need for reliable predictive, rather than correlative, models covering a wide range...... addressed to or written by industrial colleagues, are discussed initially. This provides the context of the survey and material with which the results of the survey can be compared. The results of the survey have been divided into the themes: data, models, systems, properties, education, and collaboration...... reactive systems (simultaneous chemical and physical equilibrium). Education in thermodynamics is perceived as key, for the future application of thermodynamics in the industry. A number of suggestions for improvement were made at all three levels (undergraduate, postgraduate, and professional development...

  14. Transport properties of partially ionized hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T S [IETP, Al Farabi Kazakh National University, Tole bi, 96a, 480012, Almaty (Kazakhstan); Galiyev, K Zh [IETP, Al Farabi Kazakh National University, Tole bi, 96a, 480012, Almaty (Kazakhstan); Dzhumagulova, K N [IETP, Al Farabi Kazakh National University, Tole bi, 96a, 480012, Almaty (Kazakhstan); Roepke, G [Fachbereich Physik, Universitaet Rostock, D-18051 Rostock (Germany); Redmer, R [Fachbereich Physik, Universitaet Rostock, D-18051 Rostock (Germany)

    2003-06-06

    We have considered partially ionized hydrogen plasma for the density region n{sub e} = (10{sup 18}-10{sup 22}) cm{sup -3}. Charged particles in the system (electrons, protons) interact via an effective potential taking into account three-particle correlations. We use the Buckingham polarization potential to describe electron-atom and proton-atom interactions. The electrical and thermal conductivity is determined using the Chapman-Enskog method. We compare the obtained results with other available data.

  15. Density functional theory calculations of charge transport properties of ‘plate-like’ coronene topological structures

    Indian Academy of Sciences (India)

    ZIRAN CHEN; ZHANRONG HE; YOUHUI XU; WENHAO YU

    2017-09-01

    Charge transport rate is one of the key parameters determining the performance of organic electronic devices. In this paper, we used density functional theory (DFT) at the M06-2X/6−31+G(d) level to compute the charge transport rates of nine coronene topological structures. The results show that the energy gap of these nine coronene derivatives is in the range 2.90–3.30 eV, falling into the organic semiconductor category. The size of the conjugate ring has a large influence on the charge transport properties. Incorporation of methyl groupson the rigid core of tetrabenzocoronene and hexabenzocoronene is more conducive to the hole transport of the molecule than incorporating methoxyl groups. The derivatisation of a ‘long plate-like’ coronene with methoxylgroups facilitates both hole and electron transport. This class of molecules can thus be used in the design of ambipolar transport semiconductor materials.

  16. Electronic Transport Properties of (7,0) Semiconducting Carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    SONG Jiu-Xu; YANG Yin-Wang; CHAI Chang-Chun; LIU Hong-Xia; DING Rui-Xue

    2008-01-01

    Electronic transport properties of a finite (7,0) carbon nanotube (CNT) coupled to Au (111) surfaces are investigated with a fully nonequilibrium Green's functions method combined with the density functional theory. The results show that the coupling effect between the CNT and Au electrode plays an important role in the transport properties, which leads to the formation of a high plateau in the transmission spectrum around Fermi energy. In addition, the current-voltage characteristic of the (7,0) CNT coupled to Au electrodes is different from an isolated (7,0) CNT.

  17. Prediction of transport and other physical properties of fluids

    CERN Document Server

    Bretsznajder, S

    1971-01-01

    Prediction of Transport and Other Physical Properties of Fluids reviews general methods for predicting the transport and other physical properties of fluids such as gases and liquids. Topics covered range from the theory of corresponding states and methods for estimating the surface tension of liquids to some basic concepts of the kinetic theory of gases. Methods of estimating liquid viscosity based on the principle of additivity are also described. This volume is comprised of eight chapters and opens by presenting basic information on gases and liquids as well as intermolecular forces and con

  18. Quantum-walk transport properties on graphene structures

    Science.gov (United States)

    Bougroura, Hamza; Aissaoui, Habib; Chancellor, Nicholas; Kendon, Viv

    2016-12-01

    We present numerical studies of quantum walks on C60 and related graphene structures to investigate their transport properties. Also known as a honeycomb lattice, the lattice formed by carbon atoms in the graphene phase can be rolled up to form nanotubes of various dimensions. Graphene nanotubes have many important applications, some of which rely on their unusual electrical conductivity and related properties. Quantum walks on graphs provide an abstract setting in which to study such transport properties independent of the other chemical and physical properties of a physical substance. They can thus be used to further the understanding of mechanisms behind such properties. We find that nanotube structures are significantly more efficient in transporting a quantum walk than cycles of equivalent size, provided the symmetry of the structure is respected in how they are used. We find faster transport on zigzag nanotubes compared to armchair nanotubes, which is unexpected given that for the actual materials the armchair nanotube is metallic, while the zigzag is semiconducting.

  19. METHODICAL APPROACH TO DETERMINATION OF PASSENGER TRANSPORTATION ATTRACTIVENESS ON RAILWAY TRANSPORT

    Directory of Open Access Journals (Sweden)

    N. A. Bozhok

    2014-03-01

    Full Text Available Purpose. Development of a methodological approach to determine the attractiveness of passenger traffic on the basis of competition factors. Methodology. The major factors of competition affecting the passenger traffic volumes were pointed out to achieve this purpose. Findings. There are 3 chief players in the market of passenger transport services in the long-distance: road, railway and air transport. Moreover, the competition between them is escalating. That is why there was a need for determination of railway transportation attractiveness. For this purpose the following factors of the competition were separated: price policy of a carrier; vehicle motion speed; term and rhythm of a trip; transportation quality. Each of these indicators is considered separately. As a result it gave the opportunity to construct an integrated indicator of passenger traffic attractiveness. Originality. The offered methodical approach to determine the passenger traffic attractiveness gives the opportunity to estimate it; as well it also considers the high-speed movement introduction in Ukraine. Practical value. The offered technique will give the opportunity to determine volumes of transportations more precisely. It is necessary for definition of quantity of a rolling stock for prospect.

  20. First thermochemical property of Seaborgium determined

    Energy Technology Data Exchange (ETDEWEB)

    Tuerler, A. for a LBNL Berkeley - Univ. Bern - FLNR Dubna -GSI Darmstadt - TU Dresden - Chalmers Univ. of Technology Goeteborg - GH Kassel - ITS and LLNL Livermore - Univ. Mainz - Univ. Oslo - FZ Rossendorf - JAERI Tokai - PSI Villigen collaboration

    1997-09-01

    The chemical properties of SgO{sub 2}Cl{sub 2} (element 106 = Seaborgium, Sg) were successfully studied using the On-line Gas Chromatography Apparatus (OLGA III). After chemical separation of Sg the nuclides {sup 265}Sg and {sup 266}Sg were unambiguously identified and their half-lives were determined for the first time. The Sg nuclides were produced from the {sup 248}Cm({sup 22}Ne,4,5n){sup 266,265}Sg reaction at the GSI Darmstadt UNILAC accelerator. Simultaneously, short-lived W nuclides were produced from a small admixture of {sup 152}Gd to the Cm target material. As predicted by relativistic calculations and by extrapolations of chemical properties, it was demonstrated that Sg oxychlorides are indeed less volatile than their lighter homologue Mo- and equally or less volatile than W-oxychlorides. (author) 1 fig., 1 tab., 4 refs.

  1. Properties of an affine transport equation and its holonomy

    Science.gov (United States)

    Vines, Justin; Nichols, David A.

    2016-10-01

    An affine transport equation was used recently to study properties of angular momentum and gravitational-wave memory effects in general relativity. In this paper, we investigate local properties of this transport equation in greater detail. Associated with this transport equation is a map between the tangent spaces at two points on a curve. This map consists of a homogeneous (linear) part given by the parallel transport map along the curve plus an inhomogeneous part, which is related to the development of a curve in a manifold into an affine tangent space. For closed curves, the affine transport equation defines a "generalized holonomy" that takes the form of an affine map on the tangent space. We explore the local properties of this generalized holonomy by using covariant bitensor methods to compute the generalized holonomy around geodesic polygon loops. We focus on triangles and "parallelogramoids" with sides formed from geodesic segments. For small loops, we recover the well-known result for the leading-order linear holonomy (˜ Riemann × area), and we derive the leading-order inhomogeneous part of the generalized holonomy (˜ Riemann × area^{3/2}). Our bitensor methods let us naturally compute higher-order corrections to these leading results. These corrections reveal the form of the finite-size effects that enter into the holonomy for larger loops; they could also provide quantitative errors on the leading-order results for finite loops.

  2. Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Barrufet, Maria

    2001-12-18

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibria, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

  3. Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Barufet, Maria

    2002-11-20

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

  4. Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Barrufet, Maria

    2002-11-20

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

  5. Transport Properties of Carbon-Nanotube/Cement Composites

    NARCIS (Netherlands)

    Han, B.; Yang, Z.; Shi, X.; Yu, X.

    2012-01-01

    This paper preliminarily investigates the general transport properties (i.e., water sorptivity, water permeability, and gas permeability) of carbon-nanotube/cement composites. Carboxyl multi-walled carbon nanotubes (MWNTs) are dispersed into cement mortar to fabricate the carbon nanotubes (CNTs) rei

  6. Transport Properties of the Metallic State of TMTSF-DMTCNQ

    DEFF Research Database (Denmark)

    Bechgaard, Klaus; Andersen, Jan Rud; Andrieux, A.

    1979-01-01

    The authors report the transport properties (longitudinal and transverse conductivity, magnetoresistance and thermopower) of TMTSF-DMTCNQ for pressures up to 13 kbar and temperatures down to 1.2K together with the phase diagram which results from these measurements. The most striking results are ...

  7. Transport properties of the Fermi hard-sphere system

    CERN Document Server

    Mecca, Angela; Benhar, Omar; Polls, Artur

    2015-01-01

    The transport properties of neutron star matter play an important role in a variety of astrophysical processes. We report the results of a calculation of the shear viscosity and thermal conductivity coefficients of the hard-sphere fermion system of degeneracy $\

  8. Phase Structure and Transport Properties of Dense Quark Matter

    CERN Document Server

    Schaefer, Thomas

    2010-01-01

    We provide a summary of our current knowledge of the phase structure of very dense quark matter. We concentrate on the question how the ground state at asymptotically high density -- color-flavor-locked (CFL) matter -- is modified as the density is lowered. We discuss the nature of the quasi-particle excitations, and present work on the transport properties of dense QCD matter.

  9. Transport Properties of Metallic Ruthenates: A DFT +DMFT Investigation

    Science.gov (United States)

    Deng, Xiaoyu; Haule, Kristjan; Kotliar, Gabriel

    2016-06-01

    We present a systematical theoretical study on the transport properties of an archetypal family of Hund's metals, Sr2RuO4 , Sr3 Ru2 O7 , SrRuO3 , and CaRuO3 , within the combination of first principles density functional theory and dynamical mean field theory. The agreement between theory and experiments for optical conductivity and resistivity is good, which indicates that electron-electron scattering dominates the transport of ruthenates. We demonstrate that in the single-site dynamical mean field approach the transport properties of Hund's metals fall into the scenario of "resilient quasiparticles." We explain why the single layered compound Sr2 RuO4 has a relative weak correlation with respect to its siblings, which corroborates its good metallicity.

  10. Determining physical properties of the cell cortex

    CERN Document Server

    Saha, A; Behrndt, M; Heisenberg, C -P; Jülicher, F; Grill, S W

    2015-01-01

    Actin and myosin assemble into a thin layer of a highly dynamic network underneath the membrane of eukaryotic cells. This network generates the forces that drive cell and tissue-scale morphogenetic processes. The effective material properties of this active network determine large-scale deformations and other morphogenetic events. For example,the characteristic time of stress relaxation (the Maxwell time)in the actomyosin sets the time scale of large-scale deformation of the cortex. Similarly, the characteristic length of stress propagation (the hydrodynamic length) sets the length scale of slow deformations, and a large hydrodynamic length is a prerequisite for long-ranged cortical flows. Here we introduce a method to determine physical parameters of the actomyosin cortical layer (in vivo). For this we investigate the relaxation dynamics of the cortex in response to laser ablation in the one-cell-stage {\\it C. elegans} embryo and in the gastrulating zebrafish embryo. These responses can be interpreted using ...

  11. Determination of physicochemical properties of delipidized hair.

    Science.gov (United States)

    McMullen, Roger L; Laura, Donna; Chen, Susan; Koelmel, Donald; Zhang, Guojin; Gillece, Timothy

    2013-01-01

    Using various physicochemical methods of analysis, we examined human hair in its virgin and delipidized state. Free lipids were removed by a solvent extraction technique (covalently bound lipids were not removed) using a series of solvents with varying polarity. We analyzed the surface properties of hair by conducting mechanical combing and dynamic contact angle analysis. In addition, we used inverse gas chromatography surface energy analysis to explore the chemical composition of the hair surface based on interactions of various nonpolar and polar probes with biological molecules residing on the hair surface. Further, we investigated the importance that free lipids play in the internal structural properties of hair using dynamic scanning calorimetry and tensile strength measurements. The microstructure of the hair surface was probed by atomic force microscopy, whereas the lipid content of hair's morphological components was determined by infrared spectroscopic imaging. We also monitored the water management properties of virgin and delipidized hair by dynamic vapor sorption, which yielded unique water sorption isotherms for each hair type. Using all these techniques, differences were found in the chemical composition and physical behavior of virgin and delipidized hair. To better understand the influence of hair lipid composition on hair styling treatments, we conducted mechanical analyses of hair shaped into omega loops to determine the stiffness, elasticity, and flexibility of hair-polymer assemblies. Although there were no discernible differences between untreated virgin and delipidized hair, in terms of stiffness and elasticity, we found that treatment with hair styling agents produced different effects depending on the hair type used. Likewise, streaming potential measurements were carried out to monitor the binding capacity of rinse-off treatments on virgin and delipidized hair. Using this technique, we monitored the surface potential of hair and found

  12. Structural and transport properties of directly assembled nanowires

    Science.gov (United States)

    Ozturk, Birol

    Scope and method of study. In this work, we present a systematic study on the assembly and characterization of nanostructures. We employed self and directed assembly methods in order to organize nanostructures. Quantitative film balance studies of self-assembled semiconductor nanoparticles enabled the determination of their effective interparticle potential. As a directed-assembly method, dielectrophoresis was used in the fabrication of interconnects from dispersions of nanostructures between targeted points in external circuitry. Directed electrochemical nanowire assembly (DENA) was developed and used in the fabrication of metallic nanowires from simple salt solutions. The structural and charge transport properties of the assembled nanostructures and the DENA-grown nanowires were characterized. Findings and conclusions. The CdSe nanoparticles of a given diameter were found to behave like hard-disks with significantly smaller diameters. This behavior was attributed to an attractive contribution to the interparticle potential, such as the dipolar potential. We found that nanoparticulate CdS converts to bulk CdS during dielectrophoretic interconnect fabrication. We demonstrated that the dielectrophoretic interconnects fabricated from gold nanorods are nanostructured, limiting their conductivity. DENA technique enabled the single-step growth and low-resistance interconnecting of crystalline diameter-tunable metallic nanowires. The preliminary results of the diameter-dependent resistivity studies with the DENA-grown gold nanowires were consistent with the predicted behavior.

  13. Thermodynamic and transport properties of superconducting Mg10B2.

    Science.gov (United States)

    Finnemore, D K; Ostenson, J E; Bud'ko, S L; Lapertot, G; Canfield, P C

    2001-03-12

    Transport and thermodynamic properties of a sintered pellet of the newly discovered MgB2 superconductor have been measured to determine the characteristic critical magnetic fields and critical current densities. Both resistive transition and magnetization data give similar values of the upper critical field, Hc2, with magnetization data giving dHc2/dT = 0.44 T/K at the transition temperature of Tc = 40.2 K. Close to the transition temperature, magnetization curves are thermodynamically reversible, but at low temperatures the trapped flux can be on the order of 1 T. The value of dHc/dT at Tc is estimated to be about 12 mT/K, a value similar to classical superconductors like Sn. Hence, the Ginzburg-Landau parameter kappa approximately 26. Estimates of the critical supercurrent density, Jc, using hysteresis loops and the Bean model, give critical current densities on the order of 10(5) A/cm2. Hence the supercurrent coupling through the grain boundaries is comparable to intermetallics like Nb3Sn.

  14. Transport properties of low-dimensional amorphous carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, Somnath [Nano-Electronics Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey (United Kingdom)]. E-mail: s.bhattacharyya@surrey.ac.uk; Silva, S.R.P. [Nano-Electronics Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey (United Kingdom)

    2005-06-22

    Research on amorphous carbon (a-C) to date has focused on the distinction between the sp{sup 2} and sp{sup 3} phases and understanding the properties on the basis of the sp{sup 2}-C bonded component. Recently, sufficient information on the sp{sup 2}-bonded clusters and nanoforms of carbon has helped to identify the importance of sp{sup 2}-C over sp{sup 3}-C, especially in transport properties and encouraged many groups to exploit this knowledge for device design. However, at present, few studies dedicated purely to understanding the transport properties and electronic structure of the family of a-C films as a whole is available. In this paper, we try to identify the key issues in using a-C as an unconventional semiconducting material and try to elaborate on how to overcome these hurdles in order to utilize this extremely versatile material for active device fabrication.

  15. Kinetic theory of transport processes in partially ionized reactive plasma, II: Electron transport properties

    Science.gov (United States)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-11-01

    The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion-electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases.

  16. Charge carrier transport properties in layer structured hexagonal boron nitride

    Directory of Open Access Journals (Sweden)

    T. C. Doan

    2014-10-01

    Full Text Available Due to its large in-plane thermal conductivity, high temperature and chemical stability, large energy band gap (˜ 6.4 eV, hexagonal boron nitride (hBN has emerged as an important material for applications in deep ultraviolet photonic devices. Among the members of the III-nitride material system, hBN is the least studied and understood. The study of the electrical transport properties of hBN is of utmost importance with a view to realizing practical device applications. Wafer-scale hBN epilayers have been successfully synthesized by metal organic chemical deposition and their electrical transport properties have been probed by variable temperature Hall effect measurements. The results demonstrate that undoped hBN is a semiconductor exhibiting weak p-type at high temperatures (> 700 °K. The measured acceptor energy level is about 0.68 eV above the valence band. In contrast to the electrical transport properties of traditional III-nitride wide bandgap semiconductors, the temperature dependence of the hole mobility in hBN can be described by the form of μ ∝ (T/T0−α with α = 3.02, satisfying the two-dimensional (2D carrier transport limit dominated by the polar optical phonon scattering. This behavior is a direct consequence of the fact that hBN is a layer structured material. The optical phonon energy deduced from the temperature dependence of the hole mobility is ħω = 192 meV (or 1546 cm-1, which is consistent with values previously obtained using other techniques. The present results extend our understanding of the charge carrier transport properties beyond the traditional III-nitride semiconductors.

  17. Transport properties of the Fermi hard-sphere system

    Energy Technology Data Exchange (ETDEWEB)

    Mecca, Angela; Lovato, Alessandro; Benhar, Omar; Polls, Artur

    2016-03-01

    The transport properties of neutron star matter play an important role in many astrophysical processes. We report the results of a calculation of the shear viscosity and thermal conductivity coefficients of the hard-sphere fermion system of degeneracy ν = 2, that can be regarded as a model of pure neutron matter. Our approach is based on the effective interaction obtained from the formalism of correlated basis functions and the cluster expansion technique. The resulting transport coefficients show a strong sensitivity to the quasiparticle effective mass, reflecting the effect of second-order contributions to the self-energy that are not taken into account in nuclear matter studies available in the literature.

  18. Determining Physical Properties of the Cell Cortex

    Science.gov (United States)

    Saha, Arnab; Nishikawa, Masatoshi; Behrndt, Martin; Heisenberg, Carl-Philipp; Jülicher, Frank; Grill, Stephan W.

    2016-03-01

    Actin and myosin assemble into a thin layer of a highly dynamic network underneath the membrane of eukaryotic cells. This network generates the forces that drive cell and tissue-scale morphogenetic processes. The effective material properties of this active network determine large-scale deformations and other morphogenetic events. For example,the characteristic time of stress relaxation (the Maxwell time)in the actomyosin sets the time scale of large-scale deformation of the cortex. Similarly, the characteristic length of stress propagation (the hydrodynamic length) sets the length scale of slow deformations, and a large hydrodynamic length is a prerequisite for long-ranged cortical flows. Here we introduce a method to determine physical parameters of the actomyosin cortical layer (in vivo). For this we investigate the relaxation dynamics of the cortex in response to laser ablation in the one-cell-stage {\\it C. elegans} embryo and in the gastrulating zebrafish embryo. These responses can be interpreted using a coarse grained physical description of the cortex in terms of a two dimensional thin film of an active viscoelastic gel. To determine the Maxwell time, the hydrodynamic length and the ratio of active stress and per-area friction, we evaluated the response to laser ablation in two different ways: by quantifying flow and density fields as a function of space and time, and by determining the time evolution of the shape of the ablated region. Importantly, both methods provide best fit physical parameters that are in close agreement with each other and that are similar to previous estimates in the two systems. We provide an accurate and robust means for measuring physical parameters of the actomyosin cortical layer.It can be useful for investigations of actomyosin mechanics at the cellular-scale, but also for providing insights in the active mechanics processes that govern tissue-scale morphogenesis.

  19. Metal selectivity determinants in a family of transition metal transporters.

    Science.gov (United States)

    Podar, Dorina; Scherer, Judith; Noordally, Zeenat; Herzyk, Pawel; Nies, Dietrich; Sanders, Dale

    2012-01-27

    Metal tolerance proteins (MTPs) are plant members of the cation diffusion facilitator (CDF) transporter family involved in cellular metal homeostasis. Members of the CDF family are ubiquitously found in all living entities and show principal selectivity for Zn(2+), Mn(2+), and Fe(2+). Little is known regarding metal selectivity determinants of CDFs. We identified a novel cereal member of CDFs in barley, termed HvMTP1, that localizes to the vacuolar membrane. Unlike its close relative AtMTP1, which is highly selective for Zn(2+), HvMTP1 exhibits selectivity for both Zn(2+) and Co(2+) as assessed by its ability to suppress yeast mutant phenotypes for both metals. Expression of HvMTP1/AtMTP1 chimeras in yeast revealed a five-residue sequence within the AtMTP1 N-segment of the His-rich intracytoplasmic loop that confines specificity to Zn(2+). Furthermore, mutants of AtMTP1 generated through random mutagenesis revealed residues embedded within transmembrane domain 3 that additionally specify the high degree of Zn(2+) selectivity. We propose that the His-rich loop, which might play a role as a zinc chaperone, determines the identity of the metal ions that are transported. The residues within transmembrane domain 3 can also influence metal selectivity, possibly through conformational changes induced at the cation transport site located within the membrane or at the cytoplasmic C-terminal domain.

  20. Numerically determined transport laws for fingering ("thermohaline") convection in astrophysics

    CERN Document Server

    Traxler, Adrienne; Stellmach, Stephan

    2010-01-01

    We present the first three-dimensional simulations of fingering convection performed in a parameter regime close to the one relevant for astrophysics, and reveal the existence of simple asymptotic scaling laws for turbulent heat and compositional transport. These laws can straightforwardly be extrapolated to the true astrophysical regime. Our investigation also indicates that thermocompositional "staircases," a key consequence of fingering convection in the ocean, cannot form spontaneously in stellar interiors. Our proposed empirically-determined transport laws thus provide simple prescriptions for mixing by fingering convection in a variety of astrophysical situations, and should, from here on, be used preferentially over older and less accurate parameterizations. They also establish that fingering convection does not provide sufficient extra mixing to explain observed chemical abundances in RGB stars.

  1. Coupled light transport-heat diffusion model for laser dosimetry with dynamic optical properties

    Energy Technology Data Exchange (ETDEWEB)

    London, R.A.; Glinsky, M.E.; Zimmerman, G.B.; Eder, D.C. [Lawrence Livermore National Lab., CA (United States); Jacques, S.L. [Texas Univ., Houston, TX (United States). M.D. Anderson Cancer Center

    1995-03-01

    The effect of dynamic optical properties on the spatial distribution of light in laser therapy is studied via numerical simulations. A two-dimensional, time dependent computer program called LATIS is used. Laser light transport is simulated with a Monte Carlo technique including anisotropic scattering and absorption. Thermal heat transport is calculated with a finite difference algorithm. Material properties are specified on a 2-D mesh and can be arbitrary functions of space and time. Arrhenius rate equations are solved for tissue damage caused by elevated temperatures. Optical properties are functions of tissue damage, as determined by previous measurements. Results are presented for the time variation of the light distribution and damage within the tissue as the optical properties of the tissue are altered.

  2. Transport properties of boron nanotubes investigated by ab initio calculation

    Institute of Scientific and Technical Information of China (English)

    Guo Wei; Hu Yi-Bin; Zhang Yu-Yang; Du Shi-Xuan; Gao Hong-Jun

    2009-01-01

    We investigate atomic and electronic structures of boron nanotubes (BNTs) by using the density functional theory(DFT). The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequi-librium Green function (NEGF) method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more difficult to form (N, 0) tubes than (M, M) tubes when the diameters of the two kinds of tubes are comparable. However, the (N, 0) tubes have a higher conductance than the (M, M) tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly.

  3. 1D-transport properties of single superconducting lead nanowires

    DEFF Research Database (Denmark)

    Michotte, S.; Mátéfi-Tempfli, Stefan; Piraux, L.

    2003-01-01

    We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ̃40 nm and a very large aspect ratio (̃500). The diameter of the nan......We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ̃40 nm and a very large aspect ratio (̃500). The diameter...... of the nanowire is small enough to ensure a 1D superconducting regime in a wide temperature range below T. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied DC current...

  4. Transport properties of anyons in random topological environments

    Science.gov (United States)

    Zatloukal, V.; Lehman, L.; Singh, S.; Pachos, J. K.; Brennen, G. K.

    2014-10-01

    The quasi-one-dimensional transport of Abelian and non-Abelian anyons is studied in the presence of a random topological background. In particular, we consider the quantum walk of an anyon that braids around islands of randomly filled static anyons of the same type. Two distinct behaviors are identified. We analytically demonstrate that all types of Abelian anyons localize purely due to the statistical phases induced by their random anyonic environment. In contrast, we numerically show that non-Abelian Ising anyons do not localize. This is due to their entanglement with the anyonic environment, which effectively induces dephasing. Our study demonstrates that localization properties strongly depend on nonlocal topological interactions, and it provides a clear distinction in the transport properties of Abelian and non-Abelian anyons.

  5. Stability properties of elementary dynamic models of membrane transport.

    Science.gov (United States)

    Hernández, Julio A

    2003-01-01

    Living cells are characterized by their capacity to maintain a stable steady state. For instance, cells are able to conserve their volume, internal ionic composition and electrical potential difference across the plasma membrane within values compatible with the overall cell functions. The dynamics of these cellular variables is described by complex integrated models of membrane transport. Some clues for the understanding of the processes involved in global cellular homeostasis may be obtained by the study of the local stability properties of some partial cellular processes. As an example of this approach, I perform, in this study, the neighborhood stability analysis of some elementary integrated models of membrane transport. In essence, the models describe the rate of change of the intracellular concentration of a ligand subject to active and passive transport across the plasma membrane of an ideal cell. The ligand can be ionic or nonionic, and it can affect the cell volume or the plasma membrane potential. The fundamental finding of this study is that, within the physiological range, the steady states are asymptotically stable. This basic property is a necessary consequence of the general forms of the expressions employed to describe the active and passive fluxes of the transported ligand.

  6. Molecular Dynamics Simulation on thermodynamic Properties and Transport Coefficients

    Institute of Scientific and Technical Information of China (English)

    D.X.Xiong

    1996-01-01

    Moecular dynamics simulation (MDS) is used to study the thermodynamic properties and transport coefficients of an argon system with Lennend-Jones potential.The results on the velocity distribution,mean free path,mean collison time,specific heat and self0diffusion coefficient agree well with the existing theoretical /experimental data,It shows that molecular dynamics method is another bridge to connect microworld and macreoworld.

  7. Electronic transport properties of metallic single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    曹觉先; 颜晓红; 肖杨; 丁建文

    2003-01-01

    We have calculated the differential conductance of metallic carbon nanotubes by the scatter matrix method. It is found that the differential conductance of metallic nanotube-based devices oscillates as a function of the bias voltage between the two leads and the gate voltage. Oscillation period T is directly proportional to the reciprocal of nanotube length. In addition, we found that electronic transport properties are sensitive to variation of the length of the nanotube.

  8. Determination of Some Mechanical Properties of Almond Seed ...

    African Journals Online (AJOL)

    Determination of Some Mechanical Properties of Almond Seed Related to Design of Food ... Nigerian Journal of Technological Development ... The determined engineering properties are vital for the design of postharvest handling and ...

  9. Transport properties of CNT/oligosilane/CNT heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J. [College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150080 (China); Zhang, G.L., E-mail: zglhrb@163.com [College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150080 (China); Shang, Y.; Wang, K.D.; Zhang, H.; Sun, M.; Liu, B.; Zeng, T. [College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150080 (China)

    2013-02-01

    Combining the non-equilibrium Green's function formalism with density functional theory, the transport properties of nine CNT/oligosilane/CNT heterojunctions were systematically studied. We have found that the incorporation of oligosilane linkage to the carbon nanotube mouth could significantly tune the transport properties compared with the pure oligosilane and pure CNT. The P- and B-dopings upon the oligosilane moiety could not only enhance the conductivity but also give rise to multiple negative differential resistance behavior for the CNT/oligosilane/CNT heterojunctions. The concentration of heteroatom plays an important role in the transport properties of the CNT/oligosilane/CNT heterojunctions, while the number of the oligosilane linkage exerts little effect on the conductivity. The B-doped CNT/oligosilane/CNT heterojunctions show higher conductivity than those of the P-doped ones. The p-n junction caused by B- and P-codopings exhibits a rectifying effect and the rectification ratio is up to 7.19.

  10. Experimental methods of determining thermal properties of granite

    Science.gov (United States)

    Determination of thermal properties of granite using the block method is discussed and compared with other methods. Problems that limit the accuracy of contact method in determining thermal properties of porous media are evaluated. Thermal properties of granite is determined in the laboratory with a...

  11. Thermal Transport Properties of Dry Spun Carbon Nanotube Sheets

    Directory of Open Access Journals (Sweden)

    Heath E. Misak

    2016-01-01

    Full Text Available The thermal properties of carbon nanotube- (CNT- sheet were explored and compared to copper in this study. The CNT-sheet was made from dry spinning CNTs into a nonwoven sheet. This nonwoven CNT-sheet has anisotropic properties in in-plane and out-of-plane directions. The in-plane direction has much higher thermal conductivity than the out-of-plane direction. The in-plane thermal conductivity was found by thermal flash analysis, and the out-of-plane thermal conductivity was found by a hot disk method. The thermal irradiative properties were examined and compared to thermal transport theory. The CNT-sheet was heated in the vacuum and the temperature was measured with an IR Camera. The heat flux of CNT-sheet was compared to that of copper, and it was found that the CNT-sheet has significantly higher specific heat transfer properties compared to those of copper. CNT-sheet is a potential candidate to replace copper in thermal transport applications where weight is a primary concern such as in the automobile, aircraft, and space industries.

  12. Red cell properties after different modes of blood transportation

    Directory of Open Access Journals (Sweden)

    Asya Makhro

    2016-07-01

    Full Text Available Transportation of blood samples is unavoidable for assessment of specific parameters in blood of patients with rare anemias, blood doping testing or for research purposes. Despite the awareness that shipment may substantially alter multiple parameters, no study of that extend has been performed to assess these changes and optimize shipment conditions to reduce transportation-related artifacts. Here we investigate the changes in multiple parameters in blood of healthy donors over 72 hours of simulated shipment conditions. Three different anticoagulants (K3EDTA, Sodium Heparin and citrate-based CPDA for two temperatures (4oC and room temperature were tested to define the optimal transportation conditions. Parameters measured cover common cytology and biochemistry parameters (complete blood count, hematocrit, morphological examination, red blood cell (RBC volume, ion content and density, membrane properties and stability (hemolysis, osmotic fragility, membrane heat stability, patch-clamp investigations and formation of micro vesicles, Ca2+ handling, RBC metabolism, activity of numerous enzymes and O2 transport capacity. Our findings indicate that individual sets of parameter may require different shipment settings (anticoagulants, temperature. Most of the parameters except for ion (Na+, K+, Ca2+ handling and, possibly, reticulocytes counts, tend to favor transportation at 4oC. Whereas plasma and intraerythrocytic Ca2+ cannot be accurately measured in the presence of chelators such as citrate and EDTA, majority of Ca2+-dependent parameters are stabilized in CPDA samples. Even in blood samples from healthy donors transported using optimized shipment protocol the majority of parameters were stable within 24 hours, the condition that may not hold for the samples of patients with rare anemias. This implies for the as short as possible shipping using fast courier services to the closest expert laboratory at reach. Mobile laboratories or the travel of the

  13. Symmetry properties of macroscopic transport coefficients in porous media

    Science.gov (United States)

    Lasseux, D.; Valdés-Parada, F. J.

    2017-04-01

    We report on symmetry properties of tensorial effective transport coefficients characteristic of many transport phenomena in porous systems at the macroscopic scale. The effective coefficients in the macroscopic models (derived by upscaling (volume averaging) the governing equations at the underlying scale) are obtained from the solution of closure problems that allow passing the information from the lower to the upper scale. The symmetry properties of the macroscopic coefficients are identified from a formal analysis of the closure problems and this is illustrated for several different physical mechanisms, namely, one-phase flow in homogeneous porous media involving inertial effects, slip flow in the creeping regime, momentum transport in a fracture relying on the Reynolds model including slip effects, single-phase flow in heterogeneous porous media embedding a porous matrix and a clear fluid region, two-phase momentum transport in homogeneous porous media, as well as dispersive heat and mass transport. The results from the analysis of these study cases are summarized as follows. For inertial single-phase flow, the apparent permeability tensor is irreducibly decomposed into its symmetric (viscous) and skew-symmetric (inertial) parts; for creeping slip-flow, the apparent permeability tensor is not symmetric; for one-phase slightly compressible gas flow in the slip regime within a fracture, the effective transmissivity tensor is symmetric, a result that remains valid in the absence of slip; for creeping one-phase flow in heterogeneous media, the permeability tensor is symmetric; for two-phase flow, we found the dominant permeability tensors to be symmetric, whereas the coupling tensors do not exhibit any special symmetry property; finally for dispersive heat transfer, the thermal conductivity tensors include a symmetric and a skew-symmetric part, the latter being a consequence of convective transport only. A similar result is achieved for mass dispersion. Beyond the

  14. Influence of biofilms on transport properties in porous media

    Science.gov (United States)

    Davit, Y.

    2015-12-01

    Microbial activity and biofilm growth in porous media can drastically modify transport properties such as permeability, longitudinal and transverse dispersion or effective reaction rates. Understanding these effects has proven to be a considerable challenge. Advances in this field have been hindered by the difficulty of modeling and visualizing these multi-phase non-linear effects across a broad range of spatial and temporal scales. To address these issues, we are developing a strategy that combines imaging techniques based on x-ray micro-tomography with homogenization of pore-scale transport equations. Here, we review recent progress in x-ray imaging of biofilms in porous media, with a particular focus on the contrast agents that are used to differentiate between the fluid and biofilm phases. We further show how the 3D distribution of the different phases can be used to extract specific information about the biofilm and how effective properties can be calculated via the resolution of closure problems. These closure problems are obtained using the method of volume averaging and must be adapted to the problem of interest. In hydrological systems, we show that a generic formulation for reactive solute transport is based on a domain decomposition approach at the micro-scale yielding macro-scale models reminiscent of multi-rate mass transfer approaches.

  15. Transport properties of the rough hard sphere fluid.

    Science.gov (United States)

    Kravchenko, Olga; Thachuk, Mark

    2012-01-28

    Results are presented of a systematic study of the transport properties of the rough hard sphere fluid. The rough hard sphere fluid is a simple model consisting of spherical particles that exchange linear and angular momenta, and energy upon collision. This allows a study of the sole effect of particle rotation upon fluid properties. Molecular dynamics simulations have been used to conduct extensive benchmark calculations of self-diffusion, shear and bulk viscosity, and thermal conductivity coefficients. As well, the validity of several kinetic theory equations have been examined at various levels of approximation as a function of density and translational-rotational coupling. In particular, expressions from Enskog theory using different numbers of basis sets in the representation of the distribution function were tested. Generally Enskog theory performs well at low density but deviates at larger densities, as expected. The dependence of these expressions upon translational-rotational coupling was also examined. Interestingly, even at low densities, the agreement with simulation results was sometimes not even qualitatively correct. Compared with smooth hard sphere behaviour, the transport coefficients can change significantly due to translational-rotational coupling and this effect becomes stronger the greater the coupling. Overall, the rough hard sphere fluid provides an excellent model for understanding the effects of translational-rotational coupling upon transport coefficients.

  16. Upscaling flow and transport properties in synthetic porous media

    Science.gov (United States)

    Jasinski, Lukasz; Dabrowski, Marcin

    2015-04-01

    Flow and transport through the porous media has instances in nature and industry: contaminant migration in geological formations, gas/oil extraction from proppant filled hydraulic fractures and surrounding porous matrix, underground carbon dioxide sequestration and many others. We would like to understand the behavior of propagating solute front in such medium, mainly flow preferential pathways and the solute dispersion due to the porous medium geometry. The motivation of our investigation is to find connection between the effective flow and transport properties and porous media geometry in 2D and 3D for large system sizes. The challenge is to discover a good way of upscaling flow and transport processes to obtain results comparable to these calculated on pore-scale in much faster way. We study synthetic porous media made of densely packed poly-disperse disk-or spherical-shaped grains in 2D and 3D, respectively. We use various protocols such as the random sequential addition (RSA) algorithm to generate densely packed grains. Imposed macroscopic pressure gradient invokes fluid flow through the pore space of generated porous medium samples. As the flow is considered in the low Reynolds number regime, a stationary velocity field is obtained by solving the Stokes equations by means of finite element method. Void space between the grains is accurately discretized by using body-fitting triangular or tetrahedral mesh. Finally, pure advection of a front carried by the velocity field is studied. Periodicity in all directions is applied to microstructure, flow and transport processes. Effective permeability of the media can be calculated by integrating the velocity field on cross sections, whereas effective dispersion coefficient is deduced by application of centered moment methods on the concentration field of transported solute in time. The effective parameters are investigated as a function of geometrical parameters of the media, such as porosity, specific surface area

  17. Structure and transport properties of ethylcellulose membranes with different types and granulation of magnetic powder

    Science.gov (United States)

    Krasowska, Monika; Strzelewicz, Anna; Rybak, Aleksandra; Dudek, Gabriela; Cieśla, Michał

    2016-06-01

    Structure and transport properties of ethylcellulose membranes with dispersed magnetic powder were investigated. The study mainly focused on diffusion, which is one of the transport mechanisms. The transport properties depend on many parameters like: polymeric matrix used, type of powder, its amount and granulation. The structure of the pattern formed by magnetic particles in the membrane matrix was studied. Description of the system was based on the phenomenological and molecular (random walk on a fractal lattice) approaches. Two parameters were calculated: the fractal dimension of random walk dw, and the fractal dimension of membrane structure df. The knowledge of both parameters made it possible to use the generalized equation of diffusion on the fractal structure obtained by Metzler et al. The research was carried out to determine the influence of magnetic powder granulation on the transport properties. The results showed that the random walk within the membranes of the smallest magnetic powder granulation was of the most subdiffusive character. Detailed investigation and quantitative description of gas transport through the membranes enables designing the membranes to be used in air oxygen enrichment.

  18. Morphologic and transport properties of natural organic floc

    Science.gov (United States)

    Larsen, L.G.; Harvey, J.W.; Crimaldi, J.P.

    2009-01-01

    The morphology, entrainment, and settling of suspended aggregates ("floc") significantly impact fluxes of organic carbon, nutrients, and contaminants in aquatic environments. However, transport properties of highly organic floc remain poorly understood. In this study detrital floc was collected in the Florida Everglades from two sites with different abundances of periphyton for use in a settling column and in racetrack flume entrainment experiments. Although Everglades flocs are similar to other organic aggregates in terms of morphology and settling rates, they tend to be larger and more porous than typical mineral flocs because of biostabilization processes and relatively low prevailing shear stresses typical of wetlands. Flume experiments documented that Everglades floc was entrained at a low bed shear stress of 1.0 ?? 10-2 Pa, which is considerably smaller than the typical entrainment threshold of mineral floc. Because of similarities between Everglades floc and other organic floc populations, floc transport characteristics in the Everglades typify the behavior of floc in other organic-rich shallow-water environments. Highly organic floc is more mobile than less organic floc, but because bed shear stresses in wetlands are commonly near the entrainment threshold, wetland floc dynamics are often transport-limited rather than supply limited. Organic floc transport in these environments is therefore governed by the balance between entrainment and settling fluxes, which has implications for ecosystem metabolism, materials cycling, and even landscape evolution. Copyright 2009 by the American Geophysical Union.

  19. Determining the Macroscopic Properties of Relativistic Jets

    Science.gov (United States)

    Hardee, P. E.

    2004-08-01

    The resolved relativistic jets contain structures whose observed proper motions are typically assumed to indicate the jet flow speed. In addition to structures moving with the flow, various normal mode structures such as pinching or helical and elliptical twisting can be produced by ejection events or twisting perturbations to the jet flow. The normal mode structures associated with relativistic jets, as revealed by numerical simulation, theoretical calculation, and suggested by observation, move more slowly than the jet speed. The pattern speed is related to the jet speed by the sound speed in the jet and in the surrounding medium. In the event that normal mode structures are observed, and where proper motions of pattern and flow speed are available or can be estimated, it is possible to determine the sound speed in the jet and surrounding medium. Where spatial development of normal mode structures is observed, it is possible to make inferences as to the heating rate/macroscopic viscosity of the jet fluid. Ultimately it may prove possible to separate the microscopic energization of the synchrotron radiating particles from the macroscopic heating of the jet fluid. Here I present the relevant properties of useful normal mode structures and illustrate the use of this technique. Various aspects of the work presented here have involved collaboration with I. Agudo (Max-Planck, Bonn), M.A. Aloy (Max-Planck, Garching), J. Eilek (NM Tech), J.L. Gómez (U. Valencia), P. Hughes (U. Michigan), A. Lobanov (Max-Planck, Bonn), J.M. Martí (U. Valencia), & C. Walker (NRAO).

  20. Electronic Transport Properties through Gold-Dithiol-Molecule-Gold Junctions in Equilibrium

    Institute of Scientific and Technical Information of China (English)

    NING Zhan-Yu; CHEN Jing-Zhe; HOU Shi-Min; ZHANG Jia-Xing; LIANG Zhen-Yu; ZHANG Jin; HAN Ru-Shan

    2005-01-01

    @@ We consider the electronic transport through gold-dithiol-molecule-gold junctions. We used an atomicallycontacted extended molecule model for the description of such systems. The calculations are based on the matrix Green function method combined with the hybrid tight-binding density functional theory. In order to determine the position of Fermi level, we referenced the experimental results from ultraviolet photoelectron spectroscopy.Our calculation of molecular conductance near the Fermi level qualitatively reproduces the experimental values measured previously [Science 301 (2003) 1221; J. Am. Chem. Soc. 125 (2003) 16164; Nano Lett. 4 (2004) 267].In addition, we discuss the relationship between different molecular electronic structures and transport properties.

  1. Laser patterning: A new approach to measure local magneto-transport properties in multifilamentary superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Valdes, C.F. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba); Perez-Penichet, C. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba); Noda, C. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba); Arronte, M. [Laser Technology Laboratory, CICATA-IPN, ALTAMIRA, Altamira 89600, TAMPS (Mexico); Batista-Leyva, A.J. [Department of General Physics and Mathematics, InSTEC, 10400 Havana (Cuba); Haugen, O. [Department of Physics, University of Oslo, Blindern, N-0316 Oslo (Norway); Johansen, T.H. [Department of Physics, University of Oslo, Blindern, N-0316 Oslo (Norway); Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Altshuler, E. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba)]. E-mail: ea@infomed.sld.cu

    2007-09-15

    The determination of inter- and intra-filament characteristics in superconducting composites such as BSCCO-Ag tapes is of great importance for material evaluation towards applications. Most attempts to separate the two contributions have relied on indirect methods based on magnetic measurements such as SQUID or magneto-optic imaging techniques. Here we show that laser patterning of superconducting BSCCO-Ag tapes constitutes a simple approach to measure local transport properties in a direct way, even able to separate inter- and intra-filament contributions to the overall transport behavior of the sample.

  2. Structural and robustness properties of smart-city transportation networks

    Science.gov (United States)

    Zhang, Zhen-Gang; Ding, Zhuo; Fan, Jing-Fang; Meng, Jun; Ding, Yi-Min; Ye, Fang-Fu; Chen, Xiao-Song

    2015-09-01

    The concept of smart city gives an excellent resolution to construct and develop modern cities, and also demands infrastructure construction. How to build a safe, stable, and highly efficient public transportation system becomes an important topic in the process of city construction. In this work, we study the structural and robustness properties of transportation networks and their sub-networks. We introduce a complementary network model to study the relevance and complementarity between bus network and subway network. Our numerical results show that the mutual supplement of networks can improve the network robustness. This conclusion provides a theoretical basis for the construction of public traffic networks, and it also supports reasonable operation of managing smart cities. Project supported by the Major Projects of the China National Social Science Fund (Grant No. 11 & ZD154).

  3. Transport properties of zigzag graphene nanoribbon decorated with copper clusters

    Energy Technology Data Exchange (ETDEWEB)

    Berahman, M.; Sheikhi, M. H., E-mail: msheikhi@shirazu.ac.ir [School of Electrical and Computer Eng, Shiraz University, Shiraz (Iran, Islamic Republic of); Nanotechnology Research Institute, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2014-09-07

    Using non-equilibrium green function with density functional theory, the present study investigates the transport properties of decorated zigzag graphene nanoribbon with a copper cluster. We have represented the decoration of zigzag graphene nanoribbon with single copper atom and cluster containing two and three copper atoms. In all the cases, copper atoms tend to occupy the edge state. In addition, we have shown that copper can alter the current-voltage characteristic of zigzag graphene nanoribbon and create new fluctuations and negative differential resistance. These alternations are made due to discontinuity in the combination of orbitals along the graphene nanoribbon. Decoration alters these discontinuities and creates more visible fluctuations. However, in low bias voltages, the changes are similar in all the cases. The study demonstrates that in the decorated zigzag graphene nanoribbon, the edge states are the main states for transporting electron from one electrode to another.

  4. Modeling the transport properties of epitaxially grown thermoelectric oxide thin films using spectroscopic ellipsometry

    KAUST Repository

    Sarath Kumar, S. R.

    2012-02-01

    The influence of oxygen vacancies on the transport properties of epitaxial thermoelectric (Sr,La)TiO3 thin films is determined using electrical and spectroscopic ellipsometry (SE) measurements. Oxygen vacancy concentration was varied by ex-situ annealing in Ar and Ar/H2. All films exhibited degenerate semiconducting behavior, and electrical conductivity decreased (258–133 S cm−1) with increasing oxygen content. Similar decrease in the Seebeck coefficient is observed and attributed to a decrease in effective mass (7.8–3.2 me ), as determined by SE. Excellent agreement between transport properties deduced from SE and direct electrical measurements suggests that SE is an effective tool for studying oxide thin film thermoelectrics.

  5. Transport Properties of Aqueous Glycerol and Aqueous Mannitol through the Zirconium Oxide Membrane

    Science.gov (United States)

    Blokhra; Sharma; Blokhra

    1997-08-15

    The transport properties of aqueous glycerol and aqueous mannitol across a zirconium oxide membrane are, investigated from the point of view of irreversible thermodynamics. The data on hydrodynamic permeability are analyzed in terms of frictional coefficients and entropy of activation. The phenomenological coefficient characterizing the electroosmotic flow and the membrane characteristics are also estimated for the various solutions with the object of determining the efficiencies of electrokinetic energy conversion and zeta potential. Copyright 1997Academic Press

  6. Electronic Transport Properties of Doped C28 Fullerene

    Directory of Open Access Journals (Sweden)

    Akshu Pahuja

    2014-01-01

    Full Text Available Endohedral doping of small fullerenes like C28 affects their electronic structure and increases their stability. The transport properties of Li@C28 sandwiched between two gold surfaces have been calculated using first-principles density functional theory and nonequilibrium Green’s function formalism. The transmission curves, IV characteristics, and molecular projected self-consistent Hamiltonian eigenstates of both pristine and doped molecule are computed. The current across the junction is found to decrease upon Li encapsulation, which can be attributed to change in alignment of molecular energy levels with bias voltage.

  7. Thermodynamic and transport properties of underdoped cuprates from ARPES data

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T.; Zhou, X.J.; Yagi, H.; Lu, D.H.; Tanaka, K.; Fujimori, A.; Hussain, Z.; Shen, Z.-X.; Kakeshita, T.; Eisaki, H.; Uchida, S.; Segawa, Kouji; Lavrov, A.N.; Ando, Yoichi

    2004-09-15

    The relationship between photoemission spectra of high-T{sub c} cuprates and their thermodynamic and transport properties are discussed. The doping dependence of the expected quasi-particle density at the Fermi level (E{sub F}) are compared with the electronic specific heat coefficient {gamma} and that of the spectral weight at E{sub F} with the in-plane and out-of-plane superfluid density. We have estimated the electrical resistivity of underdoped cuprates from the momentum distribution curve (MDC) at E{sub F} in the nodal direction. The temperature dependence of the MDC width is also consistent with that of the electrical resistivity.

  8. Transport properties of a ladder with two random dimer chains

    Institute of Scientific and Technical Information of China (English)

    Hu Donng-Sheng; Zhu Chen-Ping; Zhang Yong-Mei

    2011-01-01

    We investigate the transport properties of a ladder with two random dimer (RD) chains. It is found that there are two extended states in the ladder with identical RD chains and a critical state regarded as an extended state in the ladder with pairing RD chains. Such a critical state is caused by the chiral symmetry. The ladder with identical RD chains can be decoupled into two isolated RD chains and the ladder with pairing RD chains can not. The analytic expressions of the extended states are presented for the ladder with identical RD chains.

  9. Transport properties in periodically modulated zigzag silicene nanoribbon

    Science.gov (United States)

    Wang, Xiao-Shuang; Shen, Man; An, Xing-Tao; Liu, Jian-Jun

    2016-04-01

    We study theoretically the electronic transport properties of zigzag silicene nanoribbon superlattices subject to a periodic electric field perpendicular to the surface of silicene. Our results show that the conductivity of the system depends on the superlattice structural parameters and show effects analogous to those found with two-dimensional semiconductor superlattices. For a superlattice with Nb barriers, a series of resonant peaks, each of which is split into (Nb - 1) subpeaks, and transmission blockade regions appear in the conductance spectrum, which indicates the formation of minibands and minigaps. These silicene-based quantum structures can provide concepts for the design nanodevices.

  10. Transport properties of Fibonacci heterostructures: a nonparabolic approach

    Science.gov (United States)

    Palomino-Ovando, M.; Cocoletzi, G. H.

    1998-07-01

    A fourth order hamiltonian is used to explore transport properties of semiconductor Fibonacci heterostructures. The tunneling current and time delay are obtained for different Fibonacci sequences constructed withGaAsandAlxGa1 - xAs. Energy minibands are calculated to study the fractal dimension and critical electronic states in quasi-periodic arrays. Results show that nonparabolic corrections produce changes in the tunneling current, time delay and fractal dimension, and a low voltage shift of the current peaks compared with the parabolic theory. The electronic states preserve their critical nature in the presence of nonparabolic effects.

  11. Magnetoelectric and transport properties of (GaMn)Sb thin films: A ferrimagnetic phase in dilute alloys

    Science.gov (United States)

    Calderón, Jorge A.; Mesa, F.; Dussan, A.

    2017-02-01

    We studied the electrical, magnetic, and transport properties of (GaMn)Sb thin films fabricated by the direct current magnetron co-sputtering method. Using X-ray powder diffraction measurements, we identified the presence of ferrimagnetic (Mn2Sb) and ferromagnetic (Mn2Sb2) phases within the films. We also measured the magnetization of the films versus an applied magnetic field as well as their hysteresis curves at room temperature. We determined the electrical and transport properties of the films through temperature-dependent resistivity measurements using the Van Der Pauw method. The main contribution to the transport process was variable range hopping. Hopping parameters were calculated using percolation theory and refined using the diffusional model. In addition, we determined that all samples had p type semiconductor behavior, that there was an increase in the density of localized states near the Fermi level, and that the binary magnetic phases influenced the electrical properties and transport mechanisms.

  12. Transport and magnetic properties of CMR manganites with antidot arrays

    Science.gov (United States)

    Zhang, Kai; Du, Kai; Niu, Jiebin; Wei, Wengang; Chen, Jinjie; Yin, Lifeng; Shen, Jian

    2014-03-01

    We fabricated and characterized a series of manganites thin film samples with different densities of antidots. With increasing antidot density, the samples show higher MIT temperature and lower resistivity under zero and low magnetic fields. These differences become smaller and finally vanished when the magnetic field is large enough to melt the charge ordered phase in the system, which is expected in our theoretical explanations. We believe that emerging edge states at the ring of antidotes play a significant role for observed metal-insulator transition and electrical transport properties, which are of great importance of real storage and sensor device design. Magnetic property measurements and theoretical simulation also support the conclusion. These results open up new ways to control and tune the strongly correlated oxides without introduce any new material or field.

  13. Predicting the transport properties of sedimentary rocks from microgeometry

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, E.M.

    1995-02-01

    The author investigates through analysis and experiment how pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated porous media. The approach is to measure fluid permeability and electrical conductivity of rock samples using single and multiple fluid phases that can be frozen in place (wetting and nonwetting) over a range of pore pressures. These experiments are analyzed in terms of the microphysics and microchemistry of the processes involved to provide a theoretical basis for the macroscopic constitutive relationships between fluid-flow and geophysical properties that the authors develop. The purpose of these experiments and their analyses is to advance the understanding of the mechanisms and factors that control fluid transport in porous media. This understanding is important in characterizing porous media properties and heterogeneities before simulating and monitoring the progress of complex flow processes at the field scale in permeable media.

  14. Electromagnetic and transport properties of QGP within PLSM approach

    CERN Document Server

    Tawfik, Abdel Nasser

    2016-01-01

    In order to study the response of the quantum chromodynamic matter to finite electromagnetic fields, we utilize the Polyakov linear - sigma model (PLSM) in mean-field approximation. Due to participants' momentum imbalance and off-center relativistic motion of the spectators' electric charges, localized, short-lived, huge electromagnetic fields are to be generated in the relativistic heavy-ion collisions. We report on various electromagnetic and transport properties of the new-state-of matter; the quark-gluon plasma (QGP) within the QCD-like approach, PLSM. We find an excellent agreement between our PLSM calculations and various recent lattice QCD simulations and notice that the magnetization and the magnetic susceptibility and the relative permeability obviously increase in the QGP phase. We predict that increasing the magnetic field remarkable decreases the viscosity, especially in hadron phase. while in QGP phase, the viscous properties seem not being affected with.

  15. Elastic properties and electron transport in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Migunov, Vadim

    2013-02-22

    The electron transport and elastic properties of InAs nanowires grown by chemical vapor deposition on InAs (001) substrate were studied experimentally, in-situ in a transmission electron microscope (TEM). A TEM holder allowing the measurement of a nanoforce while simultaneous imaging nanowire bending was used. Diffraction images from local areas of the wire were recorded to correlate elastic properties with the atomic structure of the nanowires. Another TEM holder allowing the application of electrical bias between the nanowire and an apex of a metallic needle while simultaneous imaging the nanowire in TEM or performing electron holography was used to detect mechanical vibrations in mechanical study or holographical observation of the nanowire inner potential in the electron transport studies. The combination of the scanning probe methods with TEM allows to correlate the measured electric and elastic properties of the nanowires with direct identification of their atomic structure. It was found that the nanowires have different atomic structures and different stacking fault defect densities that impacts critically on the elastic properties and electric transport. The unique methods, that were applied in this work, allowed to obtain dependencies of resistivity and Young's modulus of left angle 111 right angle -oriented InAs nanowires on defect density and diameter. It was found that the higher is the defect density the higher are the resistivity and the Young's modulus. Regarding the resistivity, it was deduced that the stacking faults increase the scattering of the electrons in the nanowire. These findings are consistent with the literature, however, the effect described by the other groups is not so pronounced. This difference can be attributed to the significant incompleteness of the physical models used for the data analysis. Regarding the elastic modulus, there are several mechanisms affecting the elasticity of the nanowires discussed in the thesis. It

  16. Analysis Of Transport Properties of Mechanically Alloyed Lead Tin Telluride

    Science.gov (United States)

    Krishna, Rajalakshmi

    these inclusions would not be less than that expected in alloys without these inclusions while the portion of the thermal conductivity that is not due to charge carriers (the lattice thermal conductivity) would be less than what would be expected from alloys that do not have these inclusions. Furthermore, it would be possible to approximate the observed changes in the electrical and thermal transport properties using existing physical models for the scattering of electrons and phonons by small inclusions. The approach taken to investigate this hypothesis was to first experimentally characterize the mobile carrier concentration at room temperature along with the extent and type of secondary phase inclusions present in a series of three mechanically alloyed Pb1-xSnxTe alloys with different Sn content. Second, the physically based computational model was developed. This model was used to determine what the electronic conductivity, Seebeck coefficient, total thermal conductivity, and the portion of the thermal conductivity not due to mobile charge carriers would be in these particular Pb1-x SnxTe alloys if there were to be no secondary phase inclusions. Third, the electronic conductivity, Seebeck coecient and total thermal conductivity was experimentally measured for these three alloys with inclusions present at elevated temperatures. The model predictions for electrical conductivity and Seebeck coefficient were directly compared to the experimental elevated temperature electrical transport measurements. The computational model was then used to extract the lattice thermal conductivity from the experimentally measured total thermal conductivity. This lattice thermal conductivity was then compared to what would be expected from the alloys in the absence of secondary phase inclusions. Secondary phase inclusions were determined by X-ray diraction analysis to be present in all three alloys to a varying extent. The inclusions were found not to significantly degrade electrical

  17. A non-Linear transport model for determining shale rock characteristics

    Science.gov (United States)

    Ali, Iftikhar; Malik, Nadeem

    2016-04-01

    Unconventional hydrocarbon reservoirs consist of tight porous rocks which are characterised by nano-scale size porous networks with ultra-low permeability [1,2]. Transport of gas through them is not well understood at the present time, and realistic transport models are needed in order to determine rock properties and for estimating future gas pressure distribution in the reservoirs. Here, we consider a recently developed non-linear gas transport equation [3], ∂p-+ U ∂p- = D ∂2p-, t > 0, (1) ∂t ∂x ∂x2 complimented with suitable initial and boundary conditions, in order to determine shale rock properties such as the permeability K, the porosity φ and the tortuosity, τ. In our new model, the apparent convection velocity, U = U(p,px), and the apparent diffusivity D = D(p), are both highly non-linear functions of the pressure. The model incorporate various flow regimes (slip, surface diffusion, transition, continuum) based upon the Knudsen number Kn, and also includes Forchchiemers turbulence correction terms. In application, the model parameters and associated compressibility factors are fully pressure dependent, giving the model more realism than previous models. See [4]. Rock properties are determined by solving an inverse problem, with model parameters adjustment to minimise the error between the model simulation and available data. It is has been found that the proposed model performs better than previous models. Results and details of the model will be presented at the conference. Corresponding author: namalik@kfupm.edu.sa and nadeem_malik@cantab.net References [1] Cui, X., Bustin, A.M. and Bustin, R., "Measurements of gas permeability and diffusivity of tight reservoir rocks: different approaches and their applications", Geofluids 9, 208-223 (2009). [2] Chiba R., Fomin S., Chugunov V., Niibori Y. and Hashida T., "Numerical Simulation of Non Fickian Diffusion and Advection in a Fractured Porous Aquifer", AIP Conference Proceedings 898, 75 (2007

  18. Electrical transport properties of manganite powders under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M.G. [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina); Leyva, A.G. [Gerencia de Investigacion y Aplicaciones, CAC, Comision Nacional de Energia Atomica, Gral Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Acha, C., E-mail: acha@df.uba.ar [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina)

    2012-08-15

    We have measured the electrical resistance of micrometric to nanometric powders of the La{sub 5/8-y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (LPCMO with y=0.3) manganite for hydrostatic pressures up to 4 kbar. By applying different final thermal treatments to samples synthesized by a microwave assisted denitration process, we obtained two particular grain characteristic dimensions (40 nm and 1000 nm) which allowed us to analyze the grain size sensitivity of the electrical conduction properties of both the metal electrode interface with manganite (Pt/LPCMO) and the intrinsic intergranular interfaces formed by the LPCMO powder, conglomerate under the only effect of external pressure. We also analyzed the effects of pressure on the phase diagram of these powders. Our results indicate that different magnetic phases coexist at low temperatures and that the electrical transport properties are related to the intrinsic interfaces, as we observe evidences of a granular behavior and an electronic transport dominated by the Space Charge limited Current mechanism.

  19. Topological phases and transport properties of screened interacting quantum wires

    Science.gov (United States)

    Xu, Hengyi; Xiong, Ye; Wang, Jun

    2016-10-01

    We study theoretically the effects of long-range and on-site Coulomb interactions on the topological phases and transport properties of spin-orbit-coupled quasi-one-dimensional quantum wires imposed on a s-wave superconductor. The distributions of the electrostatic potential and charge density are calculated self-consistently within the Hartree approximation. Due to the finite width of the wires and charge repulsion, the potential and density distribute inhomogeneously in the transverse direction and tend to accumulate along the lateral edges where the hard-wall confinement is assumed. This result has profound effects on the topological phases and the differential conductance of the interacting quantum wires and their hybrid junctions with superconductors. Coulomb interactions renormalize the gate voltage and alter the topological phases strongly by enhancing the topological regimes and producing jagged boundaries. Moreover, the multicritical points connecting different topological phases are modified remarkably in striking contrast to the predictions of the two-band model. We further suggest the possible non-magnetic topological phase transitions manipulated externally with the aid of long-range interactions. Finally, the transport properties of normal-superconductor junctions are further examined, in particular, the impacts of Coulomb interactions on the zero-bias peaks related to the Majorana fermions and near zero-energy peaks.

  20. First-principles determination of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ruqian; Yang Zongxian; Hong Jisang [Department of Physics, University of California, Irvine, CA (United States)

    2003-02-12

    First-principles density functional theory calculations have achieved great success in the exciting field of low-dimension magnetism, in explaining new phenomena observed in experiments as well as in predicting novel properties and materials. As known, spin-orbit coupling (SOC) plays an extremely important role in various magnetic properties such as magnetic anisotropy, magnetostriction, magneto-optical effects and spin-dynamics. Using the full potential linearized augmented plane wave approach, we have carried out extensive investigations for the effects of SOC in various materials. Results of selected examples, such as structure and magnetic properties of Ni/Cu(001), magnetism and magnetic anisotropy in magnetic Co/Cu(001) thin films, wires and clusters, magnetostriction in FeGa alloys and magneto-optical effects in Fe/Cr superlattices, are discussed.

  1. TASK 7 DEMONSTRATION OF THAMES FOR MICROSTRUCTURE AND TRANSPORT PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Bullard, J.; Stutzman, P.; Snyder, K.; Garboczi, E.

    2010-03-29

    The goal of the Cementitious Barriers Partnership (CBP) is to develop a reasonable and realible set of tools to reduce the uncertainty in predicting the structural, hydraulic and chemical performance of cement barriers used in nuclear applications that are exposed to dynamic environmental conditions over extended time frames. One of these tools, the responsibility of NIST, is THAMES (Thermodynamic Hydration and Microstructure Evolution Simulator), which is being developed to describe cementitious binder microstructures and calculate important engineering properties during hydration and degradation. THAMES is designed to be a 'micro-probe', used to evaluate changes in microstructure and properties occurring over time because of hydration or degradation reactions in a volume of about 0.001 mm{sup 3}. It will be used to map out microstructural and property changes across reaction fronts, for example, with spatial resolution adequate to be input into other models (e.g., STADIUM{reg_sign}, LeachSX{trademark}) in the integrated CBP package. THAMES leverages thermodynamic predictions of equilibrium phase assemblages in aqueous geochemical systems to estimate 3-D virtual microstructures of a cementitious binder at different times during the hydration process or potentially during degradation phenomena. These virtual microstructures can then be used to calculate important engineering properties of a concrete made from that binder at prescribed times. In this way, the THAMES model provides a way to calculate the time evolution of important material properties such as elastic stiffness, compressive strength, diffusivity, and permeability. Without this model, there would be no way to update microstructure and properties for the barrier materials considered as they are exposed to the environment, thus greatly increasing the uncertainty of long-term transport predictions. This Task 7 report demonstrates the current capabilities of THAMES. At the start of the CBP

  2. Efficient calculation of dissipative quantum transport properties in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Greck, Peter

    2012-11-26

    We present a novel quantum transport method that follows the non-equilibrium Green's function (NEGF) framework but side steps any self-consistent calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. We termed this method the multi-scattering Buettiker-Probe (MSB) method. It generalizes the so-called Buettiker-Probe model but takes into account all relevant individual scattering mechanisms. It is orders of magnitude more efficient than a fully selfconsistent non-equilibrium Green's function calculation for realistic devices, yet accurately reproduces the results of the latter method as well as experimental data. This method is fairly easy to implement and opens the path towards realistic three-dimensional quantum transport calculations. In this work, we review the fundamentals of the non-equilibrium Green's function formalism for quantum transport calculations. Then, we introduce our novel MSB method after briefly reviewing the original Buettiker-Probe model. Finally, we compare the results of the MSB method to NEGF calculations as well as to experimental data. In particular, we calculate quantum transport properties of quantum cascade lasers in the terahertz (THz) and the mid-infrared (MIR) spectral domain. With a device optimization algorithm based upon the MSB method, we propose a novel THz quantum cascade laser design. It uses a two-well period with alternating barrier heights and complete carrier thermalization for the majority of the carriers within each period. We predict THz laser operation for temperatures up to 250 K implying a new temperature record.

  3. Determining the Permeable Efficiency of Elements in Transport Networks

    Directory of Open Access Journals (Sweden)

    V. Svoboda

    2001-01-01

    Full Text Available The transport network is simulated by a directed graph. Its edges are evaluated by length (in linear units or time units, by permeability and by the cost of driving through in a transport unit. Its peaks (nodes are evaluated in terms of permeability, the time of driving through the node in time units and the cost of driving a transport unit (set through this node.For such a conception of the transport network a role of optimisation and disintegration of transport flow was formulated, defined by a number of transport units (transport sets. These units enter the network at the initial node and exit the network (or vanish at the defined node. The aim of optimization was to disintegrate the transport flow so that the permeability was not exceeded in any element of the network (edge, nod, so that the relocation of the defined transport flow was completed in a prearranged time and so that the cost of driving through the transport net between the entry and exit knots was minimal.

  4. Effective Heat and Mass Transport Properties of Anisotropic Porous Ceria for Solar Thermochemical Fuel Generation

    Directory of Open Access Journals (Sweden)

    Sophia Haussener

    2012-01-01

    Full Text Available High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, and tortuosity and residence time distributions. Tailored foam designs for enhanced transport properties are examined by means of adjusting morphologies of artificial ceria samples composed of bimodal distributed overlapping transparent spheres in an opaque medium.

  5. Effective Heat and Mass Transport Properties of Anisotropic Porous Ceria for Solar Thermochemical Fuel Generation.

    Science.gov (United States)

    Haussener, Sophia; Steinfeld, Aldo

    2012-01-19

    High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, and tortuosity and residence time distributions. Tailored foam designs for enhanced transport properties are examined by means of adjusting morphologies of artificial ceria samples composed of bimodal distributed overlapping transparent spheres in an opaque medium.

  6. Transport Properties in a One-Dimensional Chain with Randomly Side-Coupled Impurities

    Institute of Scientific and Technical Information of China (English)

    胡冬生; 张桂平; 熊诗杰

    2002-01-01

    We investigate the transport properties of a one-dimensional (1D) chain with randomly side-coupled impurities.By using the transfer matrix technique, we present numerical results of the transmission coefficient as a function of the electron energy. It is found that an extended state will be shown in such a random 1D system if the impurities are side-coupled to the chain with not only the nearest-neighbour bonds but also the next-nearest-neighbour bonds. We present an analytical expression for the energy of this extended state, which is determined by the strength of the nearest and next-nearest couplings between the impurities and the chain. The obtained results can be used to explain the transport properties of DNA chains and other quasi-lD organic structures.

  7. Interface disorder and transport properties in HTC/CMR superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Haberkorn, N.; Guimpel, J.; Sirena, M.; Steren, L.B.; Campillo, G.; Saldarriaga, W.; Gomez, M.E

    2004-08-01

    The physical properties of superlattices are affected by interface disorder, like roughness and interdiffusion. X-ray diffraction allows its measurement through modeling and structure refinement. The high-T{sub c} RBa{sub 2}Cu{sub 3}O{sub 7} (RBCO) and colossal magnetoresistance La{sub x}A{sub 1-x}MnO{sub 3} (LAMO) perovskites are interesting superlattice partners given their similar lattice parameters and because the combination of magnetic and superconducting properties is interesting for both basic and applied research. We have investigated the structural and transport properties of YBCO/La{sub 2/3}Ca{sub 1/3}MnO{sub 3} and GdBCO/La{sub 0.6}Sr{sub 0.04}MnO{sub 3} superlattices grown by sputtering on (1 0 0)MgO. We find a roughness of 1 RBCO unit cell and a 30% interdiffusion in the same length from the interfaces for all samples. The superconducting behavior is found strongly dependent on the LAMO layer thickness.

  8. Electrical transport properties of single-layer WS2.

    Science.gov (United States)

    Ovchinnikov, Dmitry; Allain, Adrien; Huang, Ying-Sheng; Dumcenco, Dumitru; Kis, Andras

    2014-08-26

    We report on the fabrication of field-effect transistors based on single layers and bilayers of the semiconductor WS2 and the investigation of their electronic transport properties. We find that the doping level strongly depends on the device environment and that long in situ annealing drastically improves the contact transparency, allowing four-terminal measurements to be performed and the pristine properties of the material to be recovered. Our devices show n-type behavior with a high room-temperature on/off current ratio of ∼10(6). They show clear metallic behavior at high charge carrier densities and mobilities as high as ∼140 cm(2)/(V s) at low temperatures (above 300 cm(2)/(V s) in the case of bilayers). In the insulating regime, the devices exhibit variable-range hopping, with a localization length of about 2 nm that starts to increase as the Fermi level enters the conduction band. The promising electronic properties of WS2, comparable to those of single-layer MoS2 and WSe2, together with its strong spin-orbit coupling, make it interesting for future applications in electronic, optical, and valleytronic devices.

  9. Determination of atmospheric aerosol properties over land using satellite measurements

    NARCIS (Netherlands)

    Kokhanovsky, A.A.; Leeuw, G. de

    2009-01-01

    Mostly, aerosol properties are poorly understood because the aerosol properties are very sparse. The first workshop on the determination of atmospheric aerosol properties over land using satellite measurements is convened in Bremen, Germany. In this workshop, the topics of discussions included a var

  10. The study of thermodynamic properties and transport properties of multicomponent systems with chemical reactions

    Directory of Open Access Journals (Sweden)

    Samujlov E.

    2013-04-01

    Full Text Available In case of system with chemical reaction the most important properties are heat conductivity and heat capacity. In this work we have considered the equation for estimate the component of these properties caused by chemical reaction and ionization processes. We have evaluated the contribution of this part in heat conductivity and heat capacity too. At the high temperatures contribution in heat conductivity from ionization begins to play an important role. We have created a model, which describe partial and full ionization of gases and gas mixtures. In addition, in this work we present the comparison of our result with experimental data and data from numerical simulation. We was used the data about transport properties of middle composition of Russian coals and the data of thermophysical properties of natural gas for comparison.

  11. Spin transport properties in double quantum rings connected in series*

    Institute of Scientific and Technical Information of China (English)

    Du Jian; Wang Suxin; Pan Jianghong

    2011-01-01

    A new model of metal/semiconductor/metal double-quantum-ring connected in series is proposed and the transport properties in this model are theoretically studied. The results imply that the transmission coefficient shows periodic variations with increasing semiconductor ring size. The effects of the magnetic field and Rashba spin-orbit interaction on the transmission coefficient for two kinds of spin state electrons are different. The number of the transmission coefficient peaks is related to the length ratio between the upper ann and the half circumference of the ring. In addition, the transmission coefficient shows oscillation behavior with enhanced external magnetic field, and the corresponding average value is related to the two leads' relative position.

  12. Electronic transport properties of a quinone-based molecular switch

    Science.gov (United States)

    Zheng, Ya-Peng; Bian, Bao-An; Yuan, Pei-Pei

    2016-09-01

    In this paper, we carried out first-principles calculations based on density functional theory and non-equilibrium Green's function to investigate the electronic transport properties of a quinone-based molecule sandwiched between two Au electrodes. The molecular switch can be reversibly switched between the reduced hydroquinone (HQ) and oxidized quinone (Q) states via redox reactions. The switching behavior of two forms is analyzed through their I- V curves, transmission spectra and molecular projected self-consistent Hamiltonian at zero bias. Then we discuss the transmission spectra of the HQ and Q forms at different bias, and explain the oscillation of current according to the transmission eigenstates of LUMO energy level for Q form. The results suggest that this kind of a quinone-based molecule is usable as one of the good candidates for redox-controlled molecular switches.

  13. Direct method for calculating temperature-dependent transport properties

    Science.gov (United States)

    Liu, Yi; Yuan, Zhe; Wesselink, R. J. H.; Starikov, Anton A.; van Schilfgaarde, Mark; Kelly, Paul J.

    2015-06-01

    We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calculated from first principles. For Fe, the agreement with experiment is limited by how well the magnetization (of itinerant ferromagnets) can be calculated as a function of temperature. By introducing a simple Debye-like model of spin disorder parameterized to reproduce the experimental magnetization, the temperature dependence of the average resistivity, the anisotropic magnetoresistance, and the spin polarization of a Ni80Fe20 alloy are calculated and found to be in good agreement with existing data. Extension of the method to complex, inhomogeneous materials as well as to the calculation of other finite-temperature physical properties within the adiabatic approximation is straightforward.

  14. Symmetry analysis of transport properties in helical superconductor junctions

    Science.gov (United States)

    Cheng, Qiang; Zhang, Yinhan; Zhang, Kunhua; Jin, Biao; Zhang, Changlian

    2017-03-01

    We study the discrete symmetries satisfied by helical p-wave superconductors with the d-vectors {{k}x}\\hat{x}+/- {{k}y}\\hat{y} or {{k}y}\\hat{x}+/- {{k}x}\\hat{y} and the transformations brought by symmetry operations to ferromagnet and spin-singlet superconductors, which show intimate associations with the transport properties in heterojunctions, including helical superconductors. In particular, the partial symmetries of the Hamiltonian under spin-rotation and gauge-rotation operations are responsible for the novel invariances of the conductance in tunnel junctions and the new selection rules for the lowest current and peculiar phase diagrams in Josephson junctions, which were reported recently. The symmetries of constructed free energies for Josephson junctions are also analyzed, and are consistent with the results from the Hamiltonian.

  15. Structure and transport properties of atomic chains and molecules

    DEFF Research Database (Denmark)

    Strange, Mikkel

    2008-01-01

    conductance properties are explained in terms of a resonating-chain model, which takes the reflection probability and phase-shift of a single bulk-chain interface as the only input. The stability of silver-oxygen chains was studied with a thermodynamic model. This model has been developed in this work...... to describe tip-suspended atomically thin chains between macroscopic size electrodes. It has been tested with the use of DFT calculations on metal chains for which good agreement with experiments was obtained. To ensure the correctness of the DFT based transport calculations presented here, and in more...... tilted bridge configuration is found, with a conductance of 0.5G0 over a wide range of electrode displacements. This is in agreement with the observed peak at 0.5G0 in the experimentally obtained conductance histogram for Pt/CO [4]. Also, for homogenous Pt point contacts and short chains good agreement...

  16. Electronic transport properties of carbon nanotube metal-semiconductor-metal

    Directory of Open Access Journals (Sweden)

    F Khoeini

    2008-07-01

    Full Text Available  In this work, we study electronic transport properties of a quasi-one dimensional pure semi-conducting Zigzag Carbon Nanotube (CNT attached to semi-infinite clean metallic Zigzag CNT leads, taking into account the influence of topological defect in junctions. This structure may behave like a field effect transistor. The calculations are based on the tight-binding model and Green’s function method, in which the local density of states(LDOS in the metallic section to semi-conducting section, and muli-channel conductance of the system are calculated in the coherent and linear response regime, numerically. Also we have introduced a circuit model for the system and investigated its current. The theoretical results obtained, can be a base, for developments in designing nano-electronic devices.

  17. Magnetic and transport properties of discontinuous metal-oxides multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Dinia, A.; Schmerber, G.; Ulhaq, C.; El Bahraoui, T

    2003-02-15

    We report on structural, magnetic and transport properties of Al{sub 2}O{sub 3}/CoFe discontinuous multilayers deposited by RF sputtering at room temperature on silicon substrate. Transmission electron microscopy observations show that these multilayers consist of discontinuous layers of CoFe particles embedded in an insulating Al{sub 2}O{sub 3} matrix. This is further supported by magnetization measurements showing the presence at room temperature of both superparamagnetic and ferromagnetic components. The current-in-plane resistivity of the discontinuous multilayers has shown a negative magnetoresistance due to a spin-dependent tunneling between the CoFe magnetic particles through the insulating Al{sub 2}O{sub 3} barrier. The magnetoresistance response gives rise to two spin-dependent tunneling contributions. A contribution at small applied fields due to ferromagnetic particles and a contribution at larger magnetic applied fields due to a superparamagnetic particles.

  18. Electronic transport properties of the armchair silicon carbide nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Song Jiuxu; Yang Yintang; Liu Hongxia [Key Laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Guo Lixin [School of Science, Xidian University, Xi' an 710071 (China); Zhang Zhiyong, E-mail: songjiuxu@126.com [Information Science and Technology Institution, Northwest University, Xi' an 710069 (China)

    2010-11-15

    The electronic transport properties of the armchair silicon carbide nanotube (SiCNT) are investigated by using the combined nonequilibrium Green's function method with density functional theory. In the equilibrium transmission spectrum of the nanotube, a transmission valley of about 2.12 eV is discovered around Fermi energy, which means that the nanotube is a wide band gap semiconductor and consistent with results of first principle calculations. More important, negative differential resistance is found in its current voltage characteristic. This phenomenon originates from the variation of density of states caused by applied bias voltage. These investigations are meaningful to modeling and simulation in silicon carbide nanotube electronic devices.

  19. Electrical transport and thermoelectric properties of boron carbide nanowires

    Science.gov (United States)

    Kirihara, Kazuhiro; Mukaida, Masakazu; Shimizu, Yoshiki

    2017-04-01

    The electrical transport and thermoelectric property of boron carbide nanowires synthesized by a carbothermal method are reported. It is demonstrated that the nanowires achieve a higher Seebeck coefficient and power factor than those of the bulk samples. The conduction mechanism of the nanowires at low temperatures below 300 K is different from that of the sintered-polycrystalline and single-crystal bulk samples. In a temperature range of 200–450 K, there is a crossover between electrical conduction by variable-range hopping and phonon-assisted hopping. The inhomogeneous carbon concentration and planar defects, such as twins and stacking faults, in the nanowires are thought to modify the bonding nature and electronic structure of the boron carbide crystal substantially, causing differences in the electrical conductivity and Seebeck coefficient. The effect of boundary scattering of phonon at nanostructured surface on the thermal conductivity reduction is discussed.

  20. Transport Properties of Fluids in Micropores by Molecular Dynamics Simulation

    Institute of Scientific and Technical Information of China (English)

    LIU, Ying-Chun(刘迎春); WANG, Qi(王琦); Lü, Ling-Hong(吕玲红)

    2004-01-01

    The transport properties of fluid argon in micropores, i.e. diffusivity and viscosity, were studied by molecular dynamics simulations. The effects of pore width, temperature and density on diffusivity and viscosity were analyzed in micropores with pore widths from 0.8 to 4.0 nm. The results show that the diffusivity in micropores is much lower than the bulk diffusivity, and it decreases as the pore width decreases; but the viscosity in micropores is significantly larger than the bulk one, and it increases sharply in narrow micropores. The diffusivity in channel parallel direction is obviously larger than that in channel perpendicular direction. The temperature and density are important factors that obviously affect diffusivity and viscosity in micropores.

  1. Research on Transport Properties of HFC-227ea

    Institute of Scientific and Technical Information of China (English)

    Lin Shi; Xiaojun Liu; Yuanyuan Duan; Lizhong Han; Mingshan Zhu

    2001-01-01

    HFC-227ea(1,1,1,2,3,3,3-heptafluoropropane) is considered as a promising refrigerant alternative, especially as a component in mixtures, to replace to CFC-12, HCFC-22 and R502. But reliable transport properties data for HFC-227ea are very limited. In this paper, experimental data of viscosity along the saturation line and gaseous thermal conductivity of HFC-227ea are given. The viscosity of HFC-227ea was measured with a capillary viscometer at temperatures between 263.15 K and 333.15 K along the saturation line and its uncertainty of the results is estimated to be no more than +3%. The thermal conductivity of gaseous HFC-227ea was also measured with a transient hot-wire instrument at temperatures between 259.28 K and 341.75 K and pressures up to 1.289MPa, and its uncertainty of the results is estimated to be less than +1%.

  2. Coarse grained modeling of transport properties in monoclonal antibody solution

    Science.gov (United States)

    Swan, James; Wang, Gang

    Monoclonal antibodies and their derivatives represent the fastest growing segment of the bio pharmaceutical industry. For many applications such as novel cancer therapies, high concentration, sub-cutaneous injections of these protein solutions are desired. However, depending on the peptide sequence within the antibody, such high concentration formulations can be too viscous to inject via human derived force alone. Understanding how heterogenous charge distribution and hydrophobicity within the antibodies leads to high viscosities is crucial to their future application. In this talk, we explore a coarse grained computational model of therapeutically relevant monoclonal antibodies that accounts for electrostatic, dispersion and hydrodynamic interactions between suspended antibodies to predict assembly and transport properties in concentrated antibody solutions. We explain the high viscosities observed in many experimental studies of the same biologics.

  3. Soil properties and preferential solute transport at the field scale

    DEFF Research Database (Denmark)

    Koestel, J K; Minh, Luong Nhat; Nørgaard, Trine

    An important fraction of water flow and solute transport through soil takes place through preferential flow paths. Although this had been already observed in the nineteenth century, it had been forgotten by the scientific community until it was rediscovered during the 1970s. The awareness...... of the relevance of preferential flow was broadly re-established in the community by the early 1990s. However, since then, the notion remains widespread among soil scientists that the occurrence and strength of preferential flow cannot be predicted from measurable proxy variables such as soil properties or land...... management practices (e.g. Beven, K., 1991, modeling preferential flow - an uncertain future, Preferential Flow, 1-11). In our study, we present evidence that disproves this notion. We evaluated breakthrough curve experiments under a constant irrigation rate of 1 cm/h conducted on 65 soil columns (20 cm...

  4. Theoretical studies of the transport property of oligosilane

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The transport mechanisms of four-conjugated systems were comparatively studied by combining ATK and Gaussian 03 calculations.It was found that the charge-doped oligosilane behaved in a different way from the boron doped and phosphorus doped oligosilanes in terms of the transmission property.The charge-doped oligosilane showed almost no conductivity owing to the damage of the electron transfer path by charge-doping.By contrast,the boron doped and phosphorus doped oligosilanes were demonstrated to be good semiconductors and NDR behavior was observed for them.This is a reasonable result after the analysis of the transmission spectra,MPSH states,energy gap,conjugation effect,and scattering effect.

  5. Electron Transport Materials: Synthesis, Properties and Device Performance

    Energy Technology Data Exchange (ETDEWEB)

    Cosimbescu, Lelia; Wang, Liang; Helm, Monte L.; Polikarpov, Evgueni; Swensen, James S.; Padmaperuma, Asanga B.

    2012-06-01

    We report the design, synthesis and characterization, thermal and photophysical properties of two silane based electron transport materials, dibenzo[b,d]thiophen-2-yltriphenylsilane (Si{phi}87) and (dibenzo[b,d]thiophen-2-yl)diphenylsilane (Si{phi}88) and their performance in blue organic light emitting devices (OLEDs). The utility of these materials in blue OLEDs with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C']picolinate (Firpic) as the phosphorescent emitter was demonstrated. Using the silane Si{phi}87 as the electron transport material (ETm) an EQE of 18.2% was obtained, with a power efficiency of 24.3 lm/W (5.8V at 1mA/cm{sup 2}), in a heterostructure. When Si{phi}88 is used, the EQE is 18.5% with a power efficiency of 26.0 lm/W (5.5V at 1mA/cm{sup 2}).

  6. Compaction and transport properties of newly replicated Caulobacter crescentus DNA.

    Science.gov (United States)

    Hong, Sun-Hae; McAdams, Harley H

    2011-12-01

    Upon initiating replication of the Caulobacter chromosome, one copy of the parS centromere remains at the stalked pole; the other moves to the distal pole. We identified the segregation dynamics and compaction characteristics of newly replicated Caulobacter DNA during transport (highly variable from cell to cell) using time-lapse fluorescence microscopy. The parS centromere and a length (also highly variable) of parS proximal DNA on each arm of the chromosome are segregated with the same relatively slow transport pattern as the parS locus. Newly replicated DNA further than about 100 kb from parS segregates with a different and faster pattern, while loci at 48 kb from parS segregate with the slow pattern in some cells and the fast pattern in others. The observed parS-proximal DNA compaction characteristics have scaling properties that suggest the DNA is branched. HU2-deletion strains exhibited a reduced compaction phenotype except near the parS site where only the ΔHU1ΔHU2 double mutant had a compaction phenotype. The chromosome shows speed-dependent extension during translocation suggesting the DNA polymer is under tension. While DNA segregation is highly reliable and succeeds in virtually all wild-type cells, the high degree of cell to cell variation in the segregation process is noteworthy.

  7. Transport properties of ultrathin black phosphorus on hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Doganov, Rostislav A.; Özyilmaz, Barbaros [Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore (Singapore); Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, 28 Medical Drive, 117456 Singapore (Singapore); Koenig, Steven P.; Yeo, Yuting [Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore (Singapore); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2015-02-23

    Ultrathin black phosphorus, or phosphorene, is a two-dimensional material that allows both high carrier mobility and large on/off ratios. Similar to other atomic crystals, like graphene or layered transition metal dichalcogenides, the transport behavior of few-layer black phosphorus is expected to be affected by the underlying substrate. The properties of black phosphorus have so far been studied on the widely utilized SiO{sub 2} substrate. Here, we characterize few-layer black phosphorus field effect transistors on hexagonal boron nitride—an atomically smooth and charge trap-free substrate. We measure the temperature dependence of the field effect mobility for both holes and electrons and explain the observed behavior in terms of charged impurity limited transport. We find that in-situ vacuum annealing at 400 K removes the p-doping of few-layer black phosphorus on both boron nitride and SiO{sub 2} substrates and reduces the hysteresis at room temperature.

  8. Transport properties of liquid metal hydrogen under high pressures

    Science.gov (United States)

    Brown, R. C.; March, N. H.

    1972-01-01

    A theory is developed for the compressibility and transport properties of liquid metallic hydrogen, near to its melting point and under high pressure. The interionic force law is assumed to be of the screened Coulomb type, because hydrogen has no core electrons. The random phase approximation is used to obtain the structure factor S(k) of the system in terms of the Fourier transform of this force law. The long wavelenth limit of the structure factor S(o) is related to the compressibility, which is much lower than that of alkali metals at their melting points. The diffusion constant at the melting point is obtained in terms of the Debye frequency, using a frequency spectrum analogous with the phonon spectrum of a solid. A similar argument is used to obtain the combined shear and bulk viscosities, but these depend also on S(o). The transport coefficients are found to be about the same size as those of alkali metals at their melting points.

  9. Predicting the transport properties of sedimentary rocks from microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, Erika M. [Univ. of California, Berkeley, CA (United States)

    1995-01-01

    Understanding transport properties of sedimentary rocks, including permeability, relative permeability, and electrical conductivity, is of great importance for petroleum engineering, waste isolation, environmental restoration, and other applications. These transport properties axe controlled to a great extent by the pore structure. How pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated porous media are investigated analytically and experimentally. Hydraulic and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. Cross-sectional areas and perimeters of individual pores are estimated from two-dimensional scanning electron microscope (SEM) photomicrographs of rock sections. Results, using Berea, Boise, Massilon, and Saint-Gilles sandstones show close agreement between the predicted and measured permeabilities. Good to fair agreement is found in the case of electrical conductivity. In particular, good agreement is found for a poorly cemented rock such as Saint-Gilles sandstone, whereas the agreement is not very good for well-cemented rocks. The possible reasons for this are investigated. The surface conductance contribution of clay minerals to the overall electrical conductivity is assessed. The effect of partial hydrocarbon saturation on overall rock conductivity, and on the Archie saturation exponent, is discussed. The region of validity of the well-known Kozeny-Carman permeability formulae for consolidated porous media and their relationship to the microscopic spatial variations of channel dimensions are established. It is found that the permeabilities predicted by the Kozeny-Carman equations are valid within a factor of three of the observed values methods.

  10. Brownian dynamics determine universality of charge transport in ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Sangoro, Joshua R [ORNL; Iacob, Ciprian [University of Leipzig; Mierzwa, Michal [University of Silesia, Uniwersytecka, Katowice, Poland; Paluch, Marian [University of Silesia, Uniwersytecka, Katowice, Poland; Kremer, Friedrich [University of Leipzig

    2012-01-01

    Broadband dielectric spectroscopy is employed to investigate charge transport in a variety of glass-forming ionic liquids over wide frequency, temperature and pressure ranges. Using a combination of Einstein, Einstein-Smoluchowski, and Langevin relations, the observed universal scaling of charge transport in ionic liquids is traced back to the dominant role of Brownian dynamics.

  11. Determining the Thermal Properties of Space Lubricants

    Science.gov (United States)

    Maldonado, Christina M.

    2004-01-01

    Many mechanisms used in spacecrafts, such as satellites or the space shuttle, employ ball bearings or gears that need to be lubricated. Normally this is not a problem, but in outer space the regular lubricants that are used on Earth will not function properly. Regular lubricants will quickly vaporize in the near vacuum of space. A unique liquid called a perfluoropolyalkylether (PFPE) has an extremely low vapor pressure, around l0(exp -10) torr at 20 C, and has been used in numerous satellites and is currently used in the space shuttle. Many people refer to the PFPEs as "liquid Teflon". PFPE lubricants however, have a number of problems with them. Lubricants need many soluble additives, especially boundary and anti-wear additives, in them to function properly. All the regular known boundary additives are insoluble in PFPEs and so PFPEs lubricate poorly under highly loaded conditions leading to many malfunctioning ball bearings and gears. JAXA, the Japanese Space Agency, is designing and building a centrifuge rotor to be installed in the International Space Station. The centrifuge rotor is part of a biology lab module. They have selected a PFPE lubricant to lubricate the rotor s ball bearings and NASA bearing experts feel this is not a wise choice. An assessment of the centrifuge rotor design is being conducted by NASA and part of the assessment entails knowing the physical and thermal properties of the PFPE lubricant. One important property, the thermal diffusivity, is not known. An experimental apparatus was set up in order to measure the thermal diffusivity of the PFPE. The apparatus consists of a constant temperature heat source, cylindrical Pyrex glassware, a thermal couple and digital thermometer. The apparatus was tested and calibrated using water since the thermal diffusivity of water is known.

  12. Predictive model of transport properties of fuel cell membrane : from microscopic to macroscopic level

    Energy Technology Data Exchange (ETDEWEB)

    Colinart, T.; Lottin, O.; Maranzana, G.; Didierjean, S.; Moyne, C. [Nancy-Univ., Vandoeuvre-les-Nancy (France). Laboratoire d' Energetique et de Mecanique Theorique et Appliquee

    2007-07-01

    Because of their attractiveness as efficient and clean energy producers, proton exchange membrane fuel cells (PEMFC) can be used in automotive and small stationary applications. The electrochemical reaction takes place on two electrodes separated by a ionomer membrane. An important component of fuel cell water management and a problem for fuel cell performances involves the transport of protons from the anode to the cathode as its' transport properties are highly water dependent. Nafion membranes are widely used as an electrolyte for PEMFC. This paper presented a model to predict transport properties of polymer membranes such as Nafion used as electrolytes in a low temperature fuel cell. The paper discussed the electrical double layer that was used to determine surface charge density. The paper then discussed the analytical solution to the physical problem in the diffuse part of a cylindrical pore which involved solving the Poisson-Boltzmann, the Navier-Stokes and the Nernst-Planck equations. The properties of the electrolytic solution were equal to those of water and they were considered to be constant within the pore. A literature comparison with other models was also presented. It was concluded that in order to supplement the model, it is necessary to investigate the mechanics of the membrane, particularly the swelling behaviour, and the adsorption phenomena of the ions in the stern layer. 15 refs., 1 tab., 3 figs.

  13. Transport mechanism and regulatory properties of the human amino acid transporter ASCT2 (SLC1A5).

    Science.gov (United States)

    Scalise, Mariafrancesca; Pochini, Lorena; Panni, Simona; Pingitore, Piero; Hedfalk, Kristina; Indiveri, Cesare

    2014-11-01

    The kinetic mechanism of the transport catalyzed by the human glutamine/neutral amino acid transporter hASCT2 over-expressed in P. pastoris was determined in proteoliposomes by pseudo-bi-substrate kinetic analysis of the Na(+)-glutamineex/glutaminein transport reaction. A random simultaneous mechanism resulted from the experimental analysis. Purified functional hASCT2 was chemically cross-linked to a stable dimeric form. The oligomeric structure correlated well with the kinetic mechanism of transport. Half-saturation constants (Km) of the transporter for the other substrates Ala, Ser, Asn and Thr were measured both on the external and internal side. External Km were much lower than the internal ones confirming the asymmetry of the transporter. The electric nature of the transport reaction was determined imposing a negative inside membrane potential generated by K(+) gradients in the presence of valinomycin. The transport reaction resulted to be electrogenic and the electrogenicity originated from external Na(+). Internal Na(+) exerted a stimulatory effect on the transport activity which could be explained by a regulatory, not a counter-transport, effect. Native and deglycosylated hASCT2 extracted from HeLa showed the same transport features demonstrating that the glycosyl moiety has no role in transport function. Both in vitro and in vivo interactions of hASCT2 with the scaffold protein PDZK1 were revealed.

  14. Transport properties and nanosensors of oxide nanowires and nanobelts

    Science.gov (United States)

    Lao, Changshi

    ZnO is one of the most important materials for electronics, optoelectronics, piezoelectricity and optics. With a wide band gap of 3.37eV and an exiton binding energy of 60meV, ZnO ID nanostructures exhibit promising properties in a lot of optical device applications. It is also an important piezoelectric material and has applications in a new category of nanodevices, nano-piezotronics. Demonstrated prototype of devices includes nanogenerators, piezoelectric-FET, and a series of evolutive devices based on the concept of nanogenerator. This is based on working principle of a semiconductor and piezoelectric coupled property. This thesis is about the growth, characterization and device fabrication of ZnO nanowires and nanobelts for sensors and UV detectors. First, the fundamental synthesis of ZnO nanostructurs is investigated, particularly polar surface dominated nanostructues, to illustrate the unique growth configurations of ZnO nanobelts, nanorings and nanosprings. Detail study in this part includes nanobelts, nanorings, nanocombs, nanonetworks, and nanodiskettes synthesis. Important factors in driving the nanostructure synthesis mechanism are analyzed, such as the chemical activities of different surface of ZnO, the abundant of available Zn ions in the vapor, and the polar surface dominated effects. These factors contribute to the large abundant available ZnO nanostructures. Then, the devices fabricated methods using individual nanowires/nanobelts and their electrical transport properties were carefully characterized. In this part, dominant factors which are critical for nanobelt device performance are investigated, such as the contact properties, interface effects, and durability testing. Also, a metal doping method is studied to explore the controlling and modification of nanowire electric and optical properties. Research results obtained here provide a basic and thoroughly understanding the control process and fabrication criteria in building a functional

  15. Optical and Transport Properties of Organic Molecules: Methods and Applications

    Science.gov (United States)

    Strubbe, David Alan

    Organic molecules are versatile and tunable building blocks for technology, in nanoscale and bulk devices. In this dissertation, I will consider some important applications for organic molecules involving optical and transport properties, and develop methods and software appropriate for theoretical calculations of these properties. Specifically, we will consider second-harmonic generation, a nonlinear optical process; photoisomerization, in which absorption of light leads to mechanical motion; charge transport in junctions formed of single molecules; and optical excitations in pentacene, an organic semiconductor with applications in photovoltaics, optoelectronics, and flexible electronics. In the Introduction (Chapter 1), I will give an overview of some phenomenology about organic molecules and these application areas, and discuss the basics of the theoretical methodology I will use: density-functional theory (DFT), time-dependent density-functional theory (TDDFT), and many-body perturbation theory based on the GW approximation. In the subsequent chapters, I will further discuss, develop, and apply this methodology. 2. I will give a pedagogical derivation of the methods for calculating response properties in TDDFT, with particular focus on the Sternheimer equation, as will be used in subsequent chapters. I will review the many different response properties that can be calculated (dynamic and static) and the appropriate perturbations used to calculate them. 3. Standard techniques for calculating response use either integer occupations (as appropriate for a system with an energy gap) or fractional occupations due to a smearing function, used to improve convergence for metallic systems. I will present a generalization which can be used to compute response for a system with arbitrary fractional occupations. 4. Chloroform (CHCl3) is a small molecule commonly used as a solvent in measurements of nonlinear optics. I computed its hyperpolarizability for second

  16. Atomistic Force Field for Pyridinium-Based Ionic Liquids: Reliable Transport Properties

    DEFF Research Database (Denmark)

    Voroshylova, I. V.; Chaban, V. V.

    2014-01-01

    Reliable force field (FF) is a central issue in successful prediction of physical chemical properties via computer simulations. This work introduces refined FF parameters for six popular ionic liquids (ILs) of the pyridinium family (butylpyridinium tetrafluoroborate, bis(trifluoromethanesulfonyl)......Reliable force field (FF) is a central issue in successful prediction of physical chemical properties via computer simulations. This work introduces refined FF parameters for six popular ionic liquids (ILs) of the pyridinium family (butylpyridinium tetrafluoroborate, bis......(trifluoromethanesulfonyl)imide, dicyanamide, hexafluorophosphate, triflate, chloride). We elaborate a systematic procedure, which allows accounting for specific cationanion interactions in the liquid phase. Once these interactions are described accurately, all experimentally determined transport properties can be reproduced. We prove...

  17. Determining fate and transport parameters for nitroglycerine, 2,4-dinitrotoluine, and nitroguanidine in soils

    Science.gov (United States)

    Gosch, D. L.; Dontsova, K.; Chorover, J.; Ferré, T.; Taylor, S.

    2010-12-01

    During military operations, a small fraction of propellant mass is not consumed during firing and is deposited onto the ground surface (Jenkins et al., 2006). Soluble propellant constituents can be released from particulate residues into the environment. Propellant constituents of interest for this study are nitroglycerine (NG), 2,4-dinitrotoluine (2,4-DNT), 2,6-dinitrotoluine (2,6-DNT), and nitroguanidine (NQ). The goal of this work is to determine fate and transport parameters for these constituents in three soils that represent a range of geographic locations and soil properties. This supports a companion study that looks at dissolution of NG, 2,4-DNT, 2,6-DNT, and NQ from fired and unfired solid propellant formulations and their transport in soils. The three soils selected for the study are Catlin silt loam (fine-silty, mixed, mesic, superactive Oxyaquic Argiudoll), Plymouth sandy loam (mesic, coated Typic Quartzipsamment), and Sassafras loam (fine loamy, siliceous, mesic Typic Hapudult). Two of these soils, Plymouth sandy loam and Sassafras loam, were collected on military installations. Linear adsorption coefficients and transformation rates of propellant constituents were determined in batch kinetic experiments. Soils were mixed with propellant constituent solutions (2 mg L-1) at 4:1 solution/soil mass ratio and equilibrated for 0, 1, 2, 6, 12, 24, 48, and 120 hr at which time samples were centrifuged and supernatant solutions were analyzed for target compounds by high performance liquid chromatography (HPLC) using U.S. EPA Method 8330b for NG, 2,4-DNT, and 2,6-DNT, and Walsh (1989) method for NQ. Adsorption and transformation of propellant constituents were determined from the decrease in solution concentration of these compounds. It was determined that all studied compounds were subjected to sorption by the solid phase and degradation. Catlin soil, with finer texture and high organic matter content, influenced solution concentration of NG, 2,4-DNT, 2,6-DNT

  18. Elastic and transport properties in polycrystals of crackedgrains: Cross-property relations and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J.G.

    2007-10-02

    Some arguments of Bristow (1960) concerning the effects of cracks on elastic and transport (i.e., electrical or thermal conduction) properties of cold-worked metals are reexamined. The discussion is posed in terms of a modern understanding of bounds and estimates for physical properties of polycrystals--in contrast to Bristow's approach using simple mixture theory. One type of specialized result emphasized here is the cross-property estimates and bounds that can be obtained using the methods presented. Our results ultimately agree with those of Bristow, i.e., confirming that microcracking is not likely to be the main cause of the observed elastic behavior of cold-worked metals. However, it also becomes clear that the mixture theory approach to the analysis is too simple and that crack-crack interactions are necessary for proper quantitative study of Bristow's problem.

  19. Principle of Cross Coupling Between Vertical Heat Turbulent Transport and Vertical Velocity and Determination of Cross Coupling Coefficient

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It has been proved that there exists a cross coupling between vertical heat turbulent transport and vertical velocity by using linear thermodynamics. This result asserts that the vertical component of heat turbulent transport flux is composed of both the transport of the vertical potential temperature gralient and the coupling transport of the vertical velocity. In this paper, the coupling effect of vertical velocity on vertical heat turbulent transportation is validated by using observed data from the atmospheric boundary layer to determine cross coupling coefficients, and a series of significant properties of turbulent transportation are opened out. These properties indicate that the cross coupling coefficient is a logarithm function of the dimensionless vertical velocity and dimensionless height, and is not only related to the friction velocity u*,but also to the coupling roughness height zwo and the coupling temperature Two of the vertical velocity.In addition, the function relations suggest that only when the vertical velocity magnitude conforms to the limitation |W/u* | ≠ 1, and is above the level zwo, then the vertical velocity leads to the cross coupling effect on the vertical heat turbulent transport flux. The cross coupling theory and experimental results provide a challenge to the traditional turbulent K closure theory and the Monin-Obukhov similarity theory.

  20. A new methodology for determination of macroscopic transport parameters in drying porous media

    Science.gov (United States)

    Attari Moghaddam, A.; Kharaghani, A.; Tsotsas, E.; Prat, M.

    2015-12-01

    Two main approaches have been used to model the drying process: The first approach considers the partially saturated porous medium as a continuum and partial differential equations are used to describe the mass, momentum and energy balances of the fluid phases. The continuum-scale models (CM) obtained by this approach involve constitutive laws which require effective material properties, such as the diffusivity, permeability, and thermal conductivity which are often determined by experiments. The second approach considers the material at the pore scale, where the void space is represented by a network of pores (PN). Micro- or nanofluidics models used in each pore give rise to a large system of ordinary differential equations with degrees of freedom at each node of the pore network. In this work, the moisture transport coefficient (D), the pseudo desorption isotherm inside the network and at the evaporative surface are estimated from the post-processing of the three-dimensional pore network drying simulations for fifteen realizations of the pore space geometry from a given probability distribution. A slice sampling method is used in order to extract these parameters from PN simulations. The moisture transport coefficient obtained in this way is shown in Fig. 1a. The minimum of average D values demonstrates the transition between liquid dominated moisture transport region and vapor dominated moisture transport region; a similar behavior has been observed in previous experimental findings. A function is fitted to the average D values and then is fed into the non-linear moisture diffusion equation. The saturation profiles obtained from PN and CM simulations are shown in Fig. 1b. Figure 1: (a) extracted moisture transport coefficient during drying for fifteen realizations of the pore network, (b) average moisture profiles during drying obtained from PN and CM simulations.

  1. Electron transport properties of carbon-based nanostructures

    Science.gov (United States)

    Diaz Pinto, Carlos A.

    Grapheme and graphene-related systems have been the focus of intensive research due to their exceptional electronic behavior. Their properties have been studied for decades, from the unique band structure predicted for a single layer of graphite, to the unexpected linear magnetoresistance observed in its bulk form. Since its experimental isolation in 2004, studies on graphene monolayer, bilayer, and few-layer systems garnered an overwhelming amount of attention from the scientific community, with studies focusing on multilayers with nanometer thicknesses paling in comparison. The main motivation of this study is to further the understanding of systems consisting of multilayer graphene and ultrathin graphite (graphitic multilayers) through electron transport experiments. Uniquely designed and fabricated devices based on carbon nanostructures were used to study the transport of charge carriers under high electric and magnetic fields. For short-channel suspended graphitic multilayer devices, the two-terminal differential conductance dI/dV as a function of drain-source bias Vd displays a pronounced dip pinned at Vd=0, explained by the hot electron effect. The dip is attenuated under high magnetic fields, likely due to intra-Landau level cyclotron phonon scattering. Also, distinct high-energy dI/dV anomalies have been observed and shown to be related to intrinsic phonon-emission processes in graphite. The evolution of such dI/dV anomalies under magnetic fields is understood as a consequence of the inter-Landau level cyclotron-phonon resonance scattering. The magnetoresistance (MR) of this system shows Shubnikov-de Haas oscillations on top of a strong positive nearly-linear background. Upon the introduction of a significant amount of short-range disorders through ion implantation, the positive MR transforms into a negative MR. The results for the MR of pure and implanted graphitic multilayers can be understood by considering a recent magneto-transport theory for two

  2. Transport properties of damaged materials. Cementitious barriers partnership

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-11-01

    The objective of the Cementitious Barriers Partnership (CBP) project is to develop tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in low-level waste storage applications. One key concern for the long-term durability of concrete is the degradation of the cementitious matrix, which occurs as a result of aggressive chemical species entering the material or leaching out in the environment, depending on the exposure conditions. The objective of the experimental study described in this report is to provide experimental data relating damage in cementitious materials to changes in transport properties, which can eventually be used to support predictive model development. In order to get results within a reasonable timeframe and to induce as much as possible uniform damage level in materials, concrete samples were exposed to freezing and thawing (F/T) cycles. The methodology consisted in exposing samples to F/T cycles and monitoring damage level with ultrasonic pulse velocity measurements. Upon reaching pre-selected damage levels, samples were tested to evaluate changes in transport properties. Material selection for the study was motivated by the need to get results rapidly, in order to assess the relevance of the methodology. Consequently, samples already available at SIMCO from past studies were used. They consisted in three different concrete mixtures cured for five years in wet conditions. The mixtures had water-to-cement ratios of 0.5, 0.65 and 0.75 and were prepared with ASTM Type I cement only. The results showed that porosity is not a good indicator for damage caused by the formation of microcracks. Some materials exhibited little variations in porosity even for high damage levels. On the other hand, significant variations in tortuosity were measured in all materials. This implies that damage caused by internal pressure does not necessarily create additional pore space in

  3. Cementitious barriers partnership transport properties of damaged materials

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-11-01

    The objective of the Cementitious Barriers Partnership (CBP) project is to develop tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in low level waste storage applications. One key concern for the long-term durability of concrete is the degradation of the cementitious matrix, which occurs as a result of aggressive chemical species entering the material or leaching out in the environment, depending on the exposure conditions. The objective of the experimental study described in this report is to provide experimental data relating damage in cementitious materials to changes in transport properties, which can eventually be used to support predictive model development. In order to get results within a reasonable timeframe and to induce as much as possible uniform damage level in materials, concrete samples were exposed to freezing and thawing (F/T) cycles. The methodology consisted in exposing samples to F/T cycles and monitoring damage level with ultrasonic pulse velocity measurements. Upon reaching pre-selected damage levels, samples were tested to evaluate changes in transport properties. Material selection for the study was motivated by the need to get results rapidly, in order to assess the relevance of the methodology. Consequently, samples already available at SIMCO from past studies were used. They consisted in three different concrete mixtures cured for five years in wet conditions. The mixtures had water-to-cement ratios of 0.5, 0.65 and 0.75 and were prepared with ASTM Type I cement only. The results showed that porosity is not a good indicator for damage caused by the formation of microcracks. Some materials exhibited little variations in porosity even for high damage levels. On the other hand, significant variations in tortuosity were measured in all materials. This implies that damage caused by internal pressure do not necessarily creates additional pore space in

  4. REPRESENTING AEROSOL DYNAMICS AND PROPERTIES IN CHEMICAL TRANSPORT MODELS BY THE METHOD OF MOMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    SCHWARTZ, S.E.; MCGRAW, R.; BENKOVITZ, C.M.; WRIGHT, D.L.

    2001-04-01

    Atmospheric aerosols, suspensions of solid or liquid particles, are an important multi-phase system. Aerosols scatter and absorb shortwave (solar) radiation, affecting climate (Charlson et al., 1992; Schwartz, 1996) and visibility; nucleate cloud droplet formation, modifying the reflectivity of clouds (Twomey et al., 1984; Schwartz and Slingo, 1996) as well as contributing to composition of cloudwater and to wet deposition (Seinfeld and Pandis, 1998); and affect human health through inhalation (NRC, 1998). Existing and prospective air quality regulations impose standards on concentrations of atmospheric aerosols to protect human health and welfare (EPA, 1998). Chemical transport and transformation models representing the loading and geographical distribution of aerosols and precursor gases are needed to permit development of effective and efficient strategies for meeting air quality standards, and for examining aerosol effects on climate retrospectively and prospectively for different emissions scenarios. Important aerosol properties and processes depend on their size distribution: light scattering, cloud nucleating properties, dry deposition, and penetration into airways of lungs. The evolution of the mass loading itself depends on particle size because of the size dependence of growth and removal processes. For these reasons it is increasingly recognized that chemical transport and transformation models must represent not just the mass loading of atmospheric particulate matter but also the aerosol microphysical properties and the evolution of these properties if aerosols are to be accurately represented in these models. If the size distribution of the aerosol is known, a given property can be evaluated as the integral of the appropriate kernel function over the size distribution. This has motivated the approach of determining aerosol size distribution, and of explicitly representing this distribution and its evolution in chemical transport models.

  5. Abrasion properties of homogenous and blended fill materials during pressure hydraulic transport

    Energy Technology Data Exchange (ETDEWEB)

    Turchaninov, S.P.

    1978-03-01

    A description is given of tests conducted to determine the abrasive properties of small and large-grain free-flowing fill materials during hydraulic transport of the materials under pressure. Data are given on the size, density, abrasiveness of various sized varieties of rock, sand, and blends comprising homogenous materials, simple and complex mixtures, and on the physical characteristics of various fill materials in relation to the trafficability and parameters of pipelines. Technical specifications are given for fill steel pipes. The study indicates that the durability of hydraulic fill pipelines largely depends on the abrasiveness of the fill materials. 3 references, 2 figures, 2 tables.

  6. Determination of substrate specificity of polyamine transporters in roseobacter species

    Science.gov (United States)

    Madhuri, S.; Mou, X.

    2012-12-01

    Polyamines, such as cadaverine, putrescine, spermidine, spermine and norspermine are a class of dissolved organic nitrogen (DON) that is ubiquitously found in marine environments. Intracellular polyamines are important in a variety of biological reactions, such as nucleic acid synthesis and protein synthesis. Free polyamines in seawater can be transported into bacterial cells by ABC transporter systems, each of which consists of four components including one substrate binding protein, one ATPase and two permeases. In silico analysis of marine bacterial genomes has revealed that roseobacter, a numerically and ecologically important taxa of marine bacteria, have at least two sets of polyamine transporter genes. This study was to examine the potential preference of roseobacter to different polyamine compounds and the substrate specificity of different polyamine transporters. Eleven roseobacter species, which genomes have been sequenced, were grown in defined media supplied with single polyamine compound as the sole carbon and nitrogen source. Growth assay showed a small number of roseobacter isolates to be generalist showing no preference among the tested polyamines (Ruegeria pomeroyi DSS-3, Roseovarius sp. TM1035, Roseovarius nubinhibens ISM, Jannaschia sp. CCS1 and Sagittula stellata E-37), whereas other isolates were specilists and were specific on polyamine compounds (Roseobacter sp. CCS2 and Roseobacter denitrificans OCh 114). Primers that probe poly-1 and pot-D genes, the two genes that encode common polyamine-binding genes of polyamine transporter systems were designed using net primer and primer design program. The specificity of the primers was validated by PCR followed by amplicon sequencing. Single step reverse transcription quantitative polymerase chain reactions (RT-qPCR) was performed to investigate substrate specificity of poly-1 and pot-D genes. Key-words Roseobacter, polyamine, polyamine transporter, dissolved organic nitrogen

  7. Fundamental investigation of the transport properties of superacids in aqueous and non-aqueous media

    Science.gov (United States)

    Suarez, Sophia

    In the quest to develop more efficient energy providers one of the main focus of research has been on the improvement of ion transport. In lithium battery research this has led to the incorporation of various lithium salts, ceramics and plasticizers into the poly(ethylene)oxide (PEO) matrix, the polymer most used In Proton Conduction Membrane (PCM) fuel cell research this has led to the development of new membranes, which are designed with to replicate Nafion's ((c)DuPont) proton transport but also improve upon its deficiency of transporting intact fuel molecules and its dependence upon the presence of solvating water molecules. To better understand the process of ion transport, NMR was used to investigate dynamic properties such as D (self-diffusion coefficient) and T1 (spin-lattice relaxation time) of various proton and lithium ion-conducting systems. Ionic conductivity and viscosity measurements were also performed. The systems studied includes aqueous superacid solutions (trifluoromethanesulfonic (TFSA), para-toluenesulfonic (PTSA) and bis(trifluoromethanesulfonyl)imide (TFSI)); nano-porous (NP-) PCM's incorporating various ceramics and 3M fuel/2M H2SO4 solutions; and P(EO)20LiBETI (LiN(SO 2CF2CF3)2 composite incorporating SiO 2 ceramic nano particles. The objective of the study of the superacid solutions was to determine the effect of concentration on the transport. It was found that beyond the ionic conductivity maximum, fluctuations in both D and T1 supports the existence of local ordering in the ionic network, caused by the reduced solvent dielectric coefficient and increasing viscosity. Of the three superacids TFSA was the most conductive and most affected by reduced solvent concentration. For the P(EO)20LiBETI composite the aim was to determine the effect of the ceramic on the ion transport of the composite in a solvent free environment. Results show that the ceramic causes only modest increase in the lithium transport below 90°C. The objective in the

  8. DETERMINATION OF EFFECTIVE PROPERTIES OF FIBER-REINFORCED COMPOSITE LAMINATES

    Directory of Open Access Journals (Sweden)

    Andrzej Skrzat

    2014-06-01

    Full Text Available The determination of effective mechanical properties of multi-layer composite is presented in this paper. Computations based on finite element method predicting properties of inhomogeneous materials require solving huge tasks. More effective is Mori-Tanaka approach, typical for micromechanics problems. For regularly distributed fibers closed-forms for effective composite material properties are possible to derive. The results of homogenization are used in strength analysis of the composite pressure vessel.

  9. Determination of the Higgs boson properties with the ATLAS detector

    CERN Document Server

    Laforge, Bertrand; The ATLAS collaboration

    2016-01-01

    The results obtained from the different search channels are combined to determine global properties of the SM Higgs boson production and decay, measured at 13 TeV using about 10 fb-1 of p-p collisions.

  10. Transport properties of ion implanted poly (p-phenylene vinylene)

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, B. (LEPOFI, Faculte des Sciences, 87 Limoges (France)); Ratier, B. (LEPOFI, Faculte des Sciences, 87 Limoges (France)); Moliton, A. (LEPOFI, Faculte des Sciences, 87 Limoges (France)); Moreau, C. (Cavendish Lab., Univ. of Cambridge, Cambridge (United Kingdom)); Friend, R.H. (Cavendish Lab., Univ. of Cambridge, Cambridge (United Kingdom))

    1993-04-19

    We have studied the effect of ion implantation on transport properties (thermopower S, dc conductivity [sigma], ac conductivity [sigma][sub T]) of poly (p-phenylene vinylene). We have noticed that the thermopower sign is characteristic of the implanted ion (S > 0 for halogen, S < 0 for alkali) at low implantation energy (E [<=] 50 keV). The slope of [sigma] = f (T[sup -1]) varies, with values for activation energy between 32 meV (D = 10[sup 16] ions/cm[sup 2]) and 57 meV (D = 10[sup 15] ions/cm[sup 2]): the activation energy falls as the fluence increases in the case of implantation at low energy (E [<=] 50 keV). AC conductivity has been studied as a function of frequency v (v = 20 Hz - 1 MHz) and of temperatures T (T = 100 K - 380 K). For lower fluences (D = 2.10[sup 15] ions/cm[sup 2]), at low temperatures the ac conductivity shows hopping behaviour, switching to activated behaviour at higher temperatures. For higher fluences (D = 2.10[sup 16] ions/cm[sup 2]) the main processes are thermally activated. Thus for a high implantation energy (E = 250 keV), the related conductivity is less thermally activated and the curve [sigma][sub T] = f (1/T) slightly depends on temperature (hopping mechanism). (orig.)

  11. Transport properties of C and O in UN fuels

    Science.gov (United States)

    Schuler, Thomas; Lopes, Denise Adorno; Claisse, Antoine; Olsson, Pär

    2017-03-01

    Uranium nitride fuel is considered for fast reactors (GEN-IV generation and space reactors) and for light water reactors as a high-density fuel option. Despite this large interest, there is a lack of information about its behavior for in-pile and out-of-pile conditions. From the present literature, it is known that C and O impurities have significant influence on the fuel performance. Here we perform a systematic study of these impurities in the UN matrix using electronic-structure calculations of solute-defect interactions and microscopic jump frequencies. These quantities were calculated in the DFT +U approximation combined with the occupation matrix control scheme, to avoid convergence to metastable states for the 5 f levels. The transport coefficients of the system were evaluated with the self-consistent mean-field theory. It is demonstrated that carbon and oxygen impurities have different diffusion properties in the UN matrix, with O atoms having a higher mobility, and C atoms showing a strong flux coupling anisotropy. The kinetic interplay between solutes and vacancies is expected to be the main cause for surface segregation, as incorporation energies show no strong thermodynamic segregation preference for (001) surfaces compared with the bulk.

  12. Nanostructured semiconductors for thermoelectric energy conversion: Synthesis and transport properties

    Science.gov (United States)

    Sahoo, Pranati

    Increasing energy demands and decreasing natural energy resources have sparked search for alternative clean and renewable energy sources. For instance, currently there is a tremendous interest in thermoelectric and photovoltaic solar energy production technologies. Half-Heusler (HH) alloys are among the most popular material systems presently under widespread investigations for high temperature thermoelectric energy conversion. Approaches to increase the thermoelectric figure of merit (ZT) of HH range from (1) chemical substitution of atoms with different masses within the same atomic position in the crystal structure to optimize carrier concentration and enhance phonon scattering via mass fluctuation and (2) embedding secondary phonon scattering centers in the matrix (nanostructuring) to further reduce thermal conductivity. This work focuses on three material systems. The first part describes the synthesis and properties (thermal conductivity, electrical conductivity, magnetic) of various oxide nanostructures (NiO, Co3O4) which were subsequently used as inclusion phases in a HH matrix to reduce the thermal conductivity. Detailed reviews of the past efforts along with the current effort to optimize synthetic routes are presented. The effects of the synthesis conditions on the thermoelectric properties of compacted pellets of NiO and Co3O4 are also discussed. The second part of the work discusses the development of synthetic strategies for the fabrication of p-type and n-type bulk nanostructured thermoelectric materials made of a half-Heusler matrix based on (Ti,Hf)CoSb, containing nanostructures with full-Heusler (FH) compositions and structures coherently embedded inside the half-Heusler matrix. The role of the nanostructures in the regulation of phonon and charge carrier transports within the half-heusler matrix is extensively discussed by combining transport data and electron microscopy images. It was found that the FH nanoinclusions form staggered

  13. Electrical and thermal transport property studies of high-temperature thermoelectric materials

    Science.gov (United States)

    Bates, J. L.

    1984-12-01

    High-temperature materials that exhibit small polaron conduction appear to exhibit the highest figures of merit. A thermoelectric model based on small polaron transport has been developed. The model predicts that broad-band semiconductors with small polarons hopping along inequivalent sites of distorted sublattices can result in increases in both the electrical conductivity and the Seeback coefficient with increasing temperature without significant increases in thermal conductivity. High figures of merit (ZT), greater than 1 at 1000K, that increase with increasing temperatures are predicted. The model is being applied to the divalent metal containing (Y,LA)Cr0(3) systems with an ABO(3) perovskite structure. Transport properties have been determined for various doping elements and for different compositions. These data are being used for the evaluation of this model.

  14. Determinants of Capacity Utilization in Road Freight Transportation

    DEFF Research Database (Denmark)

    Abate, Megersa Abera

    2014-01-01

    Recent performance figures in the European road freight transport sector show that there is an excess capacity. To shed light on this phenomenon, this paper studies two aspects of capacity utilization in trucking: the extent of empty running and the load factor. The paper shows that they can...

  15. the determinants of demand for public transport services in kumasi ...

    African Journals Online (AJOL)

    dmosman.admin

    The objective of the study was to establish the major factors influencing demand as well as de- velop a demand model for urban passenger transport services in Kumasi, Ghana. .... of higher-quality services (air-conditioned, seat ... age of the vehicles within the industry is 18 ...... and Managing the Development of Kumasi,.

  16. Research Update: Structural and transport properties of (Ca,LaFeAs2 single crystal

    Directory of Open Access Journals (Sweden)

    F. Caglieris

    2016-02-01

    Full Text Available Structural and transport properties in the normal and superconducting states are investigated in a Ca0.8La0.2FeAs2 single crystal with Tc = 27 K, belonging to the newly discovered 112 family of iron based superconductors. The transport critical current density Jc for both field directions measured in a focused ion beam patterned microbridge reveals a weakly field dependent and low anisotropic behaviour with a low temperature value as high as Jc(B = 0 ∼ 105 A/cm2. This demonstrates not only bulk superconductivity but also the potential of 112 superconductors towards applications. Interestingly, this superconducting compound undergoes a structural transition below 100 K which is evidenced by temperature-dependent X-ray diffraction measurements. Data analysis of Hall resistance and magnetoresistivity indicate that magnetotransport properties are largely dominated by an electron band, with a change of regime observed in correspondence of the onset of a structural transition. In the low temperature regime, the contribution of a hole band to transport is suggested, possibly playing a role in determining the superconducting state.

  17. Research Update: Structural and transport properties of (Ca,La)FeAs{sub 2} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Caglieris, F.; Pallecchi, I.; Lamura, G.; Putti, M. [CNR-SPIN and Università di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Sala, A. [CNR-SPIN and Università di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Department of Applied Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565 (Japan); Fujioka, M. [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Hummel, F.; Johrendt, D. [Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstr. 5-13, 81377 München (Germany); Takano, Y. [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Ishida, S.; Iyo, A.; Eisaki, H. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565 (Japan); Ogino, H.; Yakita, H. [Department of Applied Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Shimoyama, J. [Department of Applied Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258 (Japan)

    2016-02-01

    Structural and transport properties in the normal and superconducting states are investigated in a Ca{sub 0.8}La{sub 0.2}FeAs{sub 2} single crystal with T{sub c} = 27 K, belonging to the newly discovered 112 family of iron based superconductors. The transport critical current density J{sub c} for both field directions measured in a focused ion beam patterned microbridge reveals a weakly field dependent and low anisotropic behaviour with a low temperature value as high as J{sub c}(B = 0) ∼ 10{sup 5} A/cm{sup 2}. This demonstrates not only bulk superconductivity but also the potential of 112 superconductors towards applications. Interestingly, this superconducting compound undergoes a structural transition below 100 K which is evidenced by temperature-dependent X-ray diffraction measurements. Data analysis of Hall resistance and magnetoresistivity indicate that magnetotransport properties are largely dominated by an electron band, with a change of regime observed in correspondence of the onset of a structural transition. In the low temperature regime, the contribution of a hole band to transport is suggested, possibly playing a role in determining the superconducting state.

  18. Effects of Climate Changes on Firn Properties and Gas Transport in Firn

    Science.gov (United States)

    Stevens, C.; Lundin, J.; Vo, H.; Yoon, M.; Waddington, E. D.

    2014-12-01

    Knowledge of the physics of firn-density evolution and gas transport in firn has several important applications in glaciology, including (1) correcting for firn air content when estimating ice-sheet mass-balance changes from satellite altimetry and (2) determining the ice-age/gas-age difference for paleoclimate interpretations of ice-core records. The firn-physics group at the University of Washington is developing modular and open-source community models describing evolution of firn density, temperature, diffusivity, and other structural properties affecting gas transport. A novel aspect is that the gas model can be coupled to the density model, allowing bubble-close-off depth, lock-in depth, depth-integrated porosity, and effective diffusivity to evolve in the gas-transport model. This feature allows us to investigate changes in firn physical properties and the evolving impacts of those changes on gas diffusion, thermal and gravitational fractionation, and the mixing ratio of gasses in bubbles trapped in firn during climate change events. Here, we use ice-core derived and synthetic climate data to show the scope of these impacts for gradual and abrupt climate changes.

  19. Research Update: Structural and transport properties of (Ca,La)FeAs2 single crystal

    Science.gov (United States)

    Caglieris, F.; Sala, A.; Fujioka, M.; Hummel, F.; Pallecchi, I.; Lamura, G.; Johrendt, D.; Takano, Y.; Ishida, S.; Iyo, A.; Eisaki, H.; Ogino, H.; Yakita, H.; Shimoyama, J.; Putti, M.

    2016-02-01

    Structural and transport properties in the normal and superconducting states are investigated in a Ca0.8La0.2FeAs2 single crystal with Tc = 27 K, belonging to the newly discovered 112 family of iron based superconductors. The transport critical current density Jc for both field directions measured in a focused ion beam patterned microbridge reveals a weakly field dependent and low anisotropic behaviour with a low temperature value as high as Jc(B = 0) ˜ 105 A/cm2. This demonstrates not only bulk superconductivity but also the potential of 112 superconductors towards applications. Interestingly, this superconducting compound undergoes a structural transition below 100 K which is evidenced by temperature-dependent X-ray diffraction measurements. Data analysis of Hall resistance and magnetoresistivity indicate that magnetotransport properties are largely dominated by an electron band, with a change of regime observed in correspondence of the onset of a structural transition. In the low temperature regime, the contribution of a hole band to transport is suggested, possibly playing a role in determining the superconducting state.

  20. The influence of doping on the electronic transport properties of InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wirths, Stephan; Weis, Karl; Volk, Christian; Alagha, Shima; Akabori, Masashi; Sladek, Kamil; Trellenkamp, Stefan; Lueth, Hans; Schaepers, Thomas; Hardtdegen, Hilde; Gruetzmacher, Detlev [Institut fuer Bio- und Nanosysteme (IBN-1), Forschungszentrum Juelich (Germany); JARA, Fundamentals of Future Information Technology (Germany)

    2010-07-01

    The investigation of the electrical conductivity of semiconductor nanowires is a crucial step on the road to zero-dimensional electronic systems. Especially the effect of Si-doping on the resistivity plays an important role and has not been investigated, yet. We study the electronic transport properties of n-doped InAs:Si nanowires grown by metal organic vapor phase epitaxy. Nominally undoped wires and Si-doped wires with four different dopant concentrations are examined. Two- and four-terminal transport measurements are performed both at room temperature and at low temperatures down to 4 K. In addition, by using a SiO{sub 2} back gate, we yield field effect transistor characteristics. Hence, the depending of conductivity on the gate voltage is determined. Moreover, we investigate the temperature dependency of transport properties. For the lowest dopant concentration we quantify {rho}=(3.8{+-}0.8) x 10{sup -4} {omega}m and {rho}=(1.8{+-}0.4) x 10{sup -5} {omega}m for the highest dopant concentration. The values of {rho} were averaged over approximately 10 to 30 wires. We can conclude, that Si-doping decreases the resistivity.

  1. The synthesis and transport properties of the complex salt /TMPD/ /TCNQ/2

    Science.gov (United States)

    Somoano, R.; Hadek, V.; Yen, S. P. S.; Rembaum, A.; Deck, R.

    1975-01-01

    The syntheses and transport properties of the complex salt /TMPD/ /TCNQ/2 are described. At high temperatures, the complex is a magnetic semiconductor with transport properties intermediate between those found in the highly conducting and poorly conducting TCNQ salts. The complex undergoes a transition below 50-60 K to a state exhibiting singlet-triplet behavior with weakly alternating exchange coupling.

  2. The phase diagram and transport properties of MgO from theory and experiment

    Science.gov (United States)

    Shulenburger, Luke

    2013-06-01

    Planetary structure and the formation of terrestrial planets have received tremendous interest due to the discovery of so called super-earth exoplanets. MgO is a major constituent of Earth's mantle, the rocky cores of gas giants and is a likely component of the interiors of many of these exoplanets. The high pressure - high temperature behavior of MgO directly affects equation of state models for planetary structure and formation. In this work, we examine MgO under extreme conditions using experimental and theoretical methods to determine its phase diagram and transport properties. Using plate impact experiments on Sandia's Z facility the solid-solid phase transition from B1 to B2 is clearly determined. The melting transition, on the other hand, is subtle, involving little to no signal in us-up space. Theoretical work utilizing density functional theory (DFT) provides a complementary picture of the phase diagram. The solid-solid phase transition is identified through a series of quasi-harmonic phonon calculations and thermodynamic integration, while the melt boundary is found using phase coexistence calculations. One issue of particular import is the calculation of reflectivity along the Hugoniot and the influence of the ionic structure on the transport properties. Particular care is necessary because of the underestimation of the band gap and attendant overestimation of transport properties due to the use of semi-local density functional theory. We will explore the impact of this theoretical challenge and its potential solutions in this talk. The integrated use of DFT simulations and high-accuracy shock experiments together provide a comprehensive understanding of MgO under extreme conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  3. Influence of metallic vapours on thermodynamic and transport properties of two-temperature air plasma

    Science.gov (United States)

    Zhong, Linlin; Wang, Xiaohua; Cressault, Yann; Teulet, Philippe; Rong, Mingzhe

    2016-09-01

    The metallic vapours (i.e., copper, iron, and silver in this paper) resulting from walls and/or electrode surfaces can significantly affect the characteristics of air plasma. Different from the previous works assuming local thermodynamic equilibrium, this paper investigates the influence of metallic vapours on two-temperature (2 T) air plasma. The 2 T compositions of air contaminated by Cu, Fe, and Ag are first determined based on Saha's and Guldberg-Waage's laws. The thermodynamic properties (including mass density, specific enthalpy, and specific heat) are then calculated according to their definitions. After determining the collision integrals for each pair of species in air-metal mixtures using the newly published methods and source data, the transport coefficients (including electrical conductivity, viscosity, and thermal conductivity) are calculated for air-Cu, air-Fe, and air-Ag plasmas with different non-equilibrium degree θ (Te/Th). The influences of metallic contamination as well as non-equilibrium degree are discussed. It is found that copper, iron, and silver exist mainly in the form of Cu2, FeO, and AgO at low temperatures. Generally, the metallic vapours increase mass density at most temperatures, reduce the specific enthalpy and specific heat in the whole temperature range, and affect the transport properties remarkably from 5000 K to 20 000 K. The effect arising from the type of metals is little except for silver at certain temperatures. Besides, the departure from thermal equilibrium results in the delay of dissociation and ionization reactions, leading to the shift of thermodynamic and transport properties towards a higher temperature.

  4. Opto-electronic and quantum transport properties of semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sabathil, M.

    2005-01-01

    In this work a novel and efficient method for the calculation of the ballistic transport properties of open semiconductor nanostructures connected to external reservoirs is presented. It is based on the Green's function formalism and reduces the effort to obtain the transmission and the carrier density to a single solution of a hermitian eigenvalue problem with dimensions proportional to the size of the decoupled device and the multiple inversion of a small matrix with dimensions proportional to the size of the contacts to the leads. Using this method, the 4-band GaAs hole transport through a 2-dimensional three-terminal T-junction device, and the resonant tunneling current through a 3-dimensional InAs quantum dot molecule embedded into an InP heterostructure have been calculated. The further extension of the method into a charge self-consistent scheme enables the efficient prediction of the IV-characteristics of highly doped nanoscale field effect transistors in the ballistic regime, including the influence of quasi bound states and the exchange-correlation interaction. Buettiker probes are used to emulate the effect of inelastic scattering on the current for simple 1D devices, systematically analyzing the dependence of the density of states and the resulting self-consistent potential on the scattering strength. The second major topic of this work is the modeling of the optical response of quantum confined neutral and charged excitons in single and coupled self-assembled InGaAs quantum dots. For this purpose the existing device simulator nextnano{sup 3} has been extended to incorporate particle-particle interactions within the means of density functional theory in local density approximation. In this way the exciton transition energies for neutral and charged excitons as a function of an externally applied electric field have been calculated, revealing a systematic reduction of the intrinsic dipole with the addition of extra holes to the exciton, a finding

  5. Possible Evidence for Stripes in the Transport Properties of PLCCO

    Science.gov (United States)

    Ando, Yoichi

    2004-03-01

    It is now recognized that the charged stripes exist surely in La_1.6-xNd_0.4Sr_xCuO_4, probably in La_2-xSr_xCuO4 (LSCO), and possibly in YBa_2Cu_3O_y. It is also recognized that an intrinsic electronic inhomogeneity exists in Bi_2Sr_2CaCu_2O_8. These observations naturally lead to a notion that some form of electron self-organization might be fundamentally related to the high-Tc superconductivity. In this context, of particular interest is whether stripes (or some electron self-organizations) exist in electron-doped cuprates as well. To investigate this issue, we took notice of two peculiar features in lightly hole-doped LSCO: (1) It was demonstrated that the anisotropic phonon heat transport is a good probe of the stripe formation in lightly-doped LSCO; namely, the spin stripes in this system are well-ordered in the CuO2 planes but are disordered along the c axis, which causes the c-axis phonons alone to be anomalously scattered [X. F. Sun et al., PRB 67, 104503 (2003)]. (2) It was also demonstrated that the in-plane resistivity ρ_ab of lightly-doped LSCO crystals shows metallic behavior (dρ_ab/dT > 0) even in the long-range-ordered Néel state, where the hole mobility is surprisingly similar to that in optimally-doped samples; such an unusual metallic behavior can naturally be understood if doped holes form self-organized ``rivers" whose distance changes with doping [Y. Ando et al., PRL 87, 017001 (2001)]. Taking these features as signatures of stripes, we examined the transport properties of lightly electron-doped Pr_1.3-xLa_0.7Ce_xCuO4 (PLCCO). It was found that both of the above unusual features are observed also in lightly-doped PLCCO, which gives possible evidence for stripes in electron-doped cuprates.

  6. Relationship between the adhesive properties of bacteria and their transport and colonization in the subsurface environment. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, M.

    1997-03-13

    The adhesion of bacteria to sediment particle or rock surfaces considerably effects their transport in subsurface environments. This research focuses on the macromolecular properties of bacteria that determine their adhesiveness and on the significance of adhesion in transport of subsurface bacteria. Specific objectives include (1) to obtain adhesion mutants of subsurface Pseudomonas species altered in surface adhesives; (2) to determine alterations in adhesives in selected mutants; (3) to evaluate the effect of adhesiveness on transport and long-term distribution and colonization of bacteria in porous media. Primary methods will be tranposon mutagenesis to generate adhesion mutants, biochemical analyses of cell surface polymers, and the use of laboratory columns containing subsurface materials to study the distribution and transport of bacteria along flow paths over time.

  7. Magnetic colloid by PLA: Optical, magnetic and thermal transport properties

    Science.gov (United States)

    Pandey, B. K.; Shahi, A. K.; Gopal, Ram

    2015-08-01

    Ferrofluids of cobalt and cobalt oxide nanoparticles (NPs) have been successfully synthesized using liquid phase-pulse laser ablation (LP-PLA) in ethanol and double distilled water, respectively. The mechanism of laser ablation in liquid media and formation process for Co target in double distilled water (DDW) and ethanol are speculated based on the reactions between laser generated highly nascent cobalt species and vaporized solvent media in a confined high temperature and pressure at the plume-surrounding liquid interface region. Optical absorption, emission, vibrational and rotational properties have been investigated using UV-vis absorption, photoluminescence (PL) and Fourier transform-infra red (FT-IR) spectroscopy, respectively. In this study optical band gap of cobalt oxide ferrofluids has been engineered using different pulse energy of Nd:YAG laser in the range of (2.80-3.60 eV). Vibrating sample magnetometer (VSM) is employed to determine the magnetic properties of ferrofluids of cobalt and cobalt oxide NPs while their thermal conductivities are examined using rotating disc method. Ferrofluids have gained enormous curiosity due to many technological applications, i.e. drug delivery, coolant and heating purposes.

  8. High field transport properties of a bilayer graphene

    Science.gov (United States)

    Bhargavi, K. S.; Kubakaddi, S. S.

    2014-02-01

    The high electric field transport properties namely, hot electron energy loss rate P, momentum loss rate Q, electron temperature Te and drift velocity Vd are studied theoretically in a bilayer graphene (BLG) by employing the momentum and energy balance technique. P and Q are investigated as a function of Te by considering the electron interaction with the acoustic phonons (APs) and the surface polar phonons (SPPs). In the Bloch-Grüneisen regime P (Q) due to APs is ~Te4 (Te2.5), with a new feature of a kink appearing due to the chiral nature of the electrons. The predicted Te4 is consistent with the recent experimental observation of heat resistance (Yan et al. Nature Nanotechnology 3 (2012) 472 [35]). Hot phonon effect is taken into account for SPPs. A dip has been observed in the hot phonon distribution of SPPs, a new feature, which is not found in conventional two-dimensional electron gas, and this can be attributed to the chiral nature of the electrons. P (Q) due to SPPs is found to be dominant at about Te>150 (180) K for a lattice temperature T=4.2 K. It is observed that the hot phonon effect is found to reduce P and Q due to SPPs significantly. Te and Vd are calculated as a function of the electric field E by taking into account the additional channels for momentum relaxation due to Coulomb impurity (CI) and short-range disorder (SD). Te is found to increase with the increasing electric field and is significantly enhanced by the hot phonon effect. Low field Vd is found to be limited by CI, SD and APs and in the high field region it reaches a near saturation value. The hot phonon effect tends to reduce the value of Vd. The presence of disorders CI and SD reduces Vd significantly and in clean samples larger saturation velocity can be achieved at a relatively smaller E.

  9. Preduction of transport properties of gases using classical nonspherical models

    Energy Technology Data Exchange (ETDEWEB)

    Verlin, J.D.

    1976-01-01

    The general formulation of the classical kinetic theory, which is needed to predict transport properties of gases in situations where the hydrodynamic equations are valid, is reviewed. A rigid convex model of tetrahedral symmetry is used to predict the Senftleben-Beenakker effect of a static magnetic field on the thermal conductivity and viscosity of pure CH/sub 4/, CD/sub 4/ and CF/sub 4/. The parameters of the model are optimized and are found to assume physically reasonable values. The calculations agree with experiment to a degree comparable to that of similar work on diatomic molecules. A generalized scattering cross section, ..gamma.., is defined which can be evaluated exactly for the limiting cases of a spherical soft potential and rigid ovaloids. For a general soft nonspherical interaction of the Kihara type, a suitable approximation for the momentum dependence is made with the following attributes: ..gamma.. reduces to the form for soft sphere and rigid ovaloid in the limits and the resulting matrix elements of the collision operator can be written in terms of the familiar ..cap omega..* integrals. This formulation is used to investigate thermal diffusion in binary isotopic mixtures of CO. Calculations are made in an 80/sup 0/K to 300/sup 0/K range which includes the inversion temperatures for all mixtures studied. Thermal conductivity and diffusion coefficients of CO are also calculated. The parameters of the model can be adjusted to account for the major features of the experimental data. The physical significance of the parameters is discussed. (auth)

  10. Identifying the Critical Links in Road Transportation Networks: Centrality-based approach utilizing structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, Supriya [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-04-01

    Surface transportation road networks share structural properties similar to other complex networks (e.g., social networks, information networks, biological networks, and so on). This research investigates the structural properties of road networks for any possible correlation with the traffic characteristics such as link flows those determined independently. Additionally, we define a criticality index for the links of the road network that identifies the relative importance in the network. We tested our hypotheses with two sample road networks. Results show that, correlation exists between the link flows and centrality measures of a link of the road (dual graph approach is followed) and the criticality index is found to be effective for one test network to identify the vulnerable nodes.

  11. Determination of petrophysical properties of sedimentary rocks by optical methods

    Science.gov (United States)

    Korte, D.; Kaukler, D.; Fanetti, M.; Cabrera, H.; Daubront, E.; Franko, M.

    2017-04-01

    Petrophysical properties of rocks (thermal diffusivity and conductivity, porosity and density) as well as the correlation between them are of great importance for many geoscientific applications. The porosity of the reservoir rocks and their permeability are the most fundamental physical properties with respect to the storage and transmission of fluids, mainly oil characterization. Accurate knowledge of these parameters for any hydrocarbon reservoir is required for efficient development, management, and prediction of future performance of the oilfield. Thus, the porosity and permeability, as well as the chemical composition must be quantified as precisely as possible. This should be done along with the thermal properties, density, conductivity, diffusivity and effusivity that are intimately related with them. For this reason, photothermal Beam Deflection Spectrometry (BDS) technique for determination of materials' thermal properties together with other methods such as Energy Dispersive X-ray Scanning Electron Microscopy (SEM-EDX) for determining the chemical composition and sample structure, as well as optical microscopy to determine the particles size, were applied for characterization of sedimentary rocks. The rocks were obtained from the Andes south flank in the Venezuela's western basin. The validation of BDS applicability for determination of petrophysical properties of three sedimentary rocks of different texture and composition (all from Late Cretaceous associated with the Luna, Capacho and Colón-Mito Juan geological formations) was performed. The rocks' thermal properties were correlated to the microstructures and chemical composition of the examined samples.

  12. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, B.Y.; Song, S.Y. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  13. Modeling silica aerogel optical performance by determining its radiative properties

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2016-02-01

    Full Text Available Silica aerogel has been known as a promising candidate for high performance transparent insulation material (TIM. Optical transparency is a crucial metric for silica aerogels in many solar related applications. Both scattering and absorption can reduce the amount of light transmitted through an aerogel slab. Due to multiple scattering, the transmittance deviates from the Beer-Lambert law (exponential attenuation. To better understand its optical performance, we decoupled and quantified the extinction contributions of absorption and scattering separately by identifying two sets of radiative properties. The radiative properties are deduced from the measured total transmittance and reflectance spectra (from 250 nm to 2500 nm of synthesized aerogel samples by solving the inverse problem of the 1-D Radiative Transfer Equation (RTE. The obtained radiative properties are found to be independent of the sample geometry and can be considered intrinsic material properties, which originate from the aerogel’s microstructure. This finding allows for these properties to be directly compared between different samples. We also demonstrate that by using the obtained radiative properties, we can model the photon transport in aerogels of arbitrary shapes, where an analytical solution is difficult to obtain.

  14. Structural Properties of the Brazilian Air Transportation Network.

    Science.gov (United States)

    Couto, Guilherme S; da Silva, Ana Paula Couto; Ruiz, Linnyer B; Benevenuto, Fabrício

    2015-09-01

    The air transportation network in a country has a great impact on the local, national and global economy. In this paper, we analyze the air transportation network in Brazil with complex network features to better understand its characteristics. In our analysis, we built networks composed either by national or by international flights. We also consider the network when both types of flights are put together. Interesting conclusions emerge from our analysis. For instance, Viracopos Airport (Campinas City) is the most central and connected airport on the national flights network. Any operational problem in this airport separates the Brazilian national network into six distinct subnetworks. Moreover, the Brazilian air transportation network exhibits small world characteristics and national connections network follows a power law distribution. Therefore, our analysis sheds light on the current Brazilian air transportation infrastructure, bringing a novel understanding that may help face the recent fast growth in the usage of the Brazilian transport network.

  15. Strategy for the use of laboratory methods in the site investigations programme for the transport properties of the rock

    Energy Technology Data Exchange (ETDEWEB)

    Widestrand, Henrik; Byegaard, Johan [Geosigma AB, Kungaelv (Sweden); Ohlsson, Yvonne [SWECO VIAK AB, Stockholm (Sweden); Tullborg, Eva-Lena [Terralogica AB, Graabo (Sweden)

    2003-06-01

    This report comprises a strategy for the handling of laboratory investigations of diffusivity and sorption characteristics within the discipline-specific programme 'Transport Properties of the Rock' in the SKB site investigations. The aim of the transport programme is to investigate the solute transport properties at a site in order to acquire data that are required for an assessment of the long-term performance and radiological safety of the deep repository. The result of the transport programme is the Transport Properties Site Descriptive Model, i.e. a description of the site-specific properties for the transport of solutes in the groundwater at a site. A strategy for the methodology, control of sampling and characterisation programme and interpretation of the results, is proposed. The basis for the laboratory investigations is a conceptual geological model based on the geological model produced in the geology programme. Major and minor types of rock and fractures are defined and characterised according to the quality of the general database and site-specific needs. The selection of samples and analyses is determined in close co-operation with the geology, hydrogeology, hydrogeochemistry and rock mechanics programmes. The result of the laboratory investigations is a retardation model, which is used as an input in the Transport Properties Site Descriptive Model. The interpretation and production of a retardation model is described and exemplified. Lastly, method-specific strategies and recommendations are given, including strategies for the selection of tracers in the experiments and for the treatment of the sampled geologic materials.

  16. Determination of Mechanical Properties of Micromembranes with Compressive Residual Stress

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel model of a load-deflection method to determine the mechanical properties of micromembranes with compressive residual stress is described. Since thin film structures are frequently used in micro devices, characterisation of mechanical properties of thin films is desired by the design and fabrication of micromachines. In this paper, the mechanical properties of thin micromembranes under compressive stress are characterised, which are fabricated by bulk micromachining. The relation between the center deflection and the load pressure on a square membrane is deduced by modelling the membrane as an elastic plate having large deflection with clamped boundaries. According to the model, whether the membrane has initial deflection or not has no effect on the measurement result. The Young's modulus and residual stress are simultaneously determined. The mechanical properties of siliconoxide, silicon nitride membranes and composite membranes of polysilicon with silicon nitride are measured.

  17. Proximity Labeling Reveals Molecular Determinants of FGFR4 Endosomal Transport.

    Science.gov (United States)

    Haugsten, Ellen Margrethe; Sørensen, Vigdis; Kunova Bosakova, Michaela; de Souza, Gustavo Antonio; Krejci, Pavel; Wiedlocha, Antoni; Wesche, Jørgen

    2016-10-07

    The fibroblast growth factor receptors (FGFRs) are important oncogenes promoting tumor progression in many types of cancer, such as breast, bladder, and lung cancer as well as multiple myeloma and rhabdomyosarcoma. However, little is known about how these receptors are internalized and down-regulated in cells. We have here applied proximity biotin labeling to identify proteins involved in FGFR4 signaling and trafficking. For this purpose we fused a mutated biotin ligase, BirA*, to the C-terminal tail of FGFR4 (FGFR4-BirA*) and the fusion protein was stably expressed in U2OS cells. Upon addition of biotin to these cells, proteins in proximity to the FGFR4-BirA* fusion protein became biotinylated and could be isolated and identified by quantitative mass spectrometry. We identified in total 291 proteins, including 80 proteins that were enriched in samples where the receptor was activated by the ligand (FGF1), among them several proteins previously found to be involved in FGFR signaling (e.g., FRS2, PLCγ, RSK2 and NCK2). Interestingly, many of the identified proteins were implicated in endosomal transport, and by precise annotation we were able to trace the intracellular pathways of activated FGFR4. Validating the data by confocal and three-dimensional structured illumination microscopy analysis, we concluded that FGFR4 uses clathrin-mediated endocytosis for internalization and is further sorted from early endosomes to the recycling compartment and the trans-Golgi network. Depletion of cells for clathrin heavy chain led to accumulation of FGFR4 at the cell surface and increased levels of active FGFR4 and PLCγ, while AKT and ERK signaling was diminished, demonstrating that functional clathrin-mediated endocytosis is required for proper FGFR4 signaling. Thus, this study reveals proteins and pathways involved in FGFR4 transport and signaling that provide possible targets and opportunities for therapeutic intervention in FGFR4 aberrant cancer.

  18. Computer program for calculation of thermodynamic and transport properties of complex chemical systems

    Science.gov (United States)

    Svehla, R. A.; Mcbride, B. J.

    1973-01-01

    Program performs calculations such as chemical equilibrium for assigned thermodynamic states, theoretical rocket performance for both equilibrium and frozen compositions during expansion, incident and reflected shock properties, and Chapman-Jouget detonation properties. Features include simplicity of input and storage of all thermodynamic and transport property data on master tape.

  19. Understanding hopping transport and thermoelectric properties of conducting polymers

    OpenAIRE

    Ihnatsenka, Siarhei; Crispin, Xavier; Zozoulenko, Igor

    2015-01-01

    We calculate the conductivity sigma and the Seebeck coefficient S for the phonon-assisted hopping transport in conducting polymers poly(3,4-ethylenedioxythiophene) or PEDOT, experimentally studied by Bubnova et al. [J. Am. Chem. Soc. 134, 16456 (2012)]. We use the Monte Carlo technique as well as the semianalytical approach based on the transport energy concept. We demonstrate that both approaches show a good qualitative agreement for the concentration dependence of sigma and S. At the same t...

  20. Detecting the local transport properties and the dimensionality of transport of epitaxial graphene by a multi-point probe approach

    DEFF Research Database (Denmark)

    Barreto, Lucas; Perkins, Edward; Johannsen, Jens;

    2013-01-01

    The electronic transport properties of epitaxial monolayer graphene (MLG) and hydrogen-intercalated quasi free-standing bilayer graphene (QFBLG) on SiC(0001) are investigated by micro multi-point probes. Using a probe with 12 contacts, we perform four-point probe measurements with the possibility...

  1. Radcalc for Windows 2.0 transportation packaging software to determine hydrogen generation and transportation classification

    Energy Technology Data Exchange (ETDEWEB)

    Green, J.R.

    1996-10-21

    Radclac for Windows is a user friendly menu-driven Windows compatible software program with applications in the transportation of radioactive materials. It calculates the radiolytic generation of hydrogen gas in the matrix of low-level and high-level radioactive wastes. It also calculates pressure buildup due to hydrogen and the decay heat generated in a package at seal time. It computes the quantity of a radionuclide and its associated products for a given period of time. In addition, the code categorizes shipment quantities as reportable quantity (RQ), radioactive Type A or Type B, limited quality (LQ), low specific activity (LSA), highway road controlled quality (HRCQ), and fissile excepted using US Department of Transportation (DOT) definitions and methodologies.

  2. Using regression models to determine the poroelastic properties of cartilage.

    Science.gov (United States)

    Chung, Chen-Yuan; Mansour, Joseph M

    2013-07-26

    The feasibility of determining biphasic material properties using regression models was investigated. A transversely isotropic poroelastic finite element model of stress relaxation was developed and validated against known results. This model was then used to simulate load intensity for a wide range of material properties. Linear regression equations for load intensity as a function of the five independent material properties were then developed for nine time points (131, 205, 304, 390, 500, 619, 700, 800, and 1000s) during relaxation. These equations illustrate the effect of individual material property on the stress in the time history. The equations at the first four time points, as well as one at a later time (five equations) could be solved for the five unknown material properties given computed values of the load intensity. Results showed that four of the five material properties could be estimated from the regression equations to within 9% of the values used in simulation if time points up to 1000s are included in the set of equations. However, reasonable estimates of the out of plane Poisson's ratio could not be found. Although all regression equations depended on permeability, suggesting that true equilibrium was not realized at 1000s of simulation, it was possible to estimate material properties to within 10% of the expected values using equations that included data up to 800s. This suggests that credible estimates of most material properties can be obtained from tests that are not run to equilibrium, which is typically several thousand seconds.

  3. Waveguide sensor with metamaterial structure for determination of dielectric properties

    Science.gov (United States)

    Steigmann, R.; Savin, A.; Isteníková, K.; Faktorová, D.; Fabo, P.

    2017-08-01

    Microwave sensor (MWS) compared with classical sensor, offers many advantage such as rapid and nondestructive measurement. At microwave (MW) frequencies, dielectric properties of materials depend on frequency, moisture content, bulk density and temperature. MW waveguide sensors can measure properties of materials based on MW interaction with matter, and provide information about dielectric properties of investigated dielectric material, characterized with complex permittivity. The paper presents a new approach for determination of the dielectric properties of dielectric material by embedding a metamaterial (MM) structure over the aperture of waveguide sensor in order to increase the sensing properties of classical waveguide sensor. The optimal design of MM structure for waveguide sensor tuning in MW X-band is obtained. In this new approach the MM function in two ways: like a tool for increasing the sensibility of classical waveguide sensor and the tool sensitive to the dielectric properties of investigated material through the adjusted resonance frequency of designed MM units. The numerical simulation of 2D MM structure properties and experimental results for dielectric properties of dielectric materials are carried out.

  4. Carbon materials with quasi-graphene layers: The dielectric, percolation properties and the electronic transport mechanism

    Institute of Scientific and Technical Information of China (English)

    Lu Ming-Ming; Yuan Jie; Wen Bo; Liu Jia; Cao Wen-Qiang; Cao Mao-Sheng

    2013-01-01

    We investigate the dielectric properties of muhi-walled carbon nanotubes (MWCNTs) and graphite filling in SiO2 with the filling concentration of 2-20 wt.% in the frequency range of 102-107 Hz.M WCNTs and graphite have general electrical properties and percolation phenomena owing to their quasi-structure made up of graphene layers.Both permittivity ε and conductivity σ exhibit jumps around the percolation threshold.Variations of dielectric properties of the composites are in agreement with the percolation theory.All the percolation phenomena are determined by hopping and migrating electrons,which are attributed to the special electronic transport mechanism of the fillers in the composites.However,the twin-percolation phenomenon exists when the concentration of MWCNTs is between 5-10 wt.% and 15-20 wt.% in the MWCNTs/SiO2 composites,while in the graphite/SiO2 composites,there is only one percolation phenomenon in the graphite concentration of 10-15 wt.%.The unique twin-percolation phenomenon of MWCNTs/SiO2 is described and attributed to the electronic transfer mechanism,especially the network effect of MWCNTs in the composites.The network formation plays an essential role in determining the second percolation threshold of MWCNTs/SiO2.

  5. Attempt at determining selected parameters of gravitational transport of ash and water or ash-brine mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Postawa, J.

    1984-03-01

    This paper discusses results of laboratory investigations into hydraulic transport of hardening mixtures which are used for stowing in underground coal mines in Poland. Two types of hardening mixtures are used: fly ash from the Jaworzno I power plant or the Leg power plant and water or fly ash and brine. The following proportions of fly ash and water are used: 1.5:1, 2:1, 2.5:1 and 3.0:1. Proportion of fly ash and brine ranges from 1.5:1 to 2.5:1. Critical transport velocity of mixtures depending on physical properties of fly ash, proportion of fly ash and water or brine and pipeline diameter is determined. Equations for calculating the optimum conditions of hydraulic transport of hardening stowing are derived. Factors which influence range of hydraulic stowing and stowing efficiency are analyzed. The results of analyses are given in 6 diagrams and 4 tables. (4 refs.) (In Polish)

  6. Ionic structures and transport properties of hot dense W and U plasmas

    Science.gov (United States)

    Hou, Yong; Yuan, Jianmin

    2016-10-01

    We have combined the average-atom model with the hyper-netted chain approximation (AAHNC) to describe the electronic and ionic structure of uranium and tungsten in the hot dense matter regime. When the electronic structure is described within the average-atom model, the effects of others ions on the electronic structure are considered by the correlation functions. And the ionic structure is calculated though using the hyper-netted chain (HNC) approximation. The ion-ion pair potential is calculated using the modified Gordon-Kim model based on the electronic density distribution in the temperature-depended density functional theory. And electronic and ionic structures are determined self-consistently. On the basis of the ion-ion pair potential, we perform the classical (CMD) and Langevin (LMD) molecular dynamics to simulate the ionic transport properties, such as ionic self-diffusion and shear viscosity coefficients, through the ionic velocity correlation functions. Due that the free electrons become more and more with increasing the plasma temperature, the influence of the electron-ion collisions on the transport properties become more and more important.

  7. Transport properties in dilute UN (X ) solid solutions (X =Xe ,Kr )

    Science.gov (United States)

    Claisse, Antoine; Schuler, Thomas; Lopes, Denise Adorno; Olsson, Pär

    2016-11-01

    Uranium nitride (UN) is a candidate fuel for current GEN III fission reactors, for which it is investigated as an accident-tolerant fuel, as well as for future GEN IV reactors. In this study, we investigate the kinetic properties of gas fission products (Xe and Kr) in UN. Binding and migration energies are obtained using density functional theory, with an added Hubbard correlation to model f electrons, and the occupation matrix control scheme to avoid metastable states. These energies are then used as input for the self-consistent mean field method which enables to determine transport coefficients for vacancy-mediated diffusion of Xe and Kr on the U sublattice. The magnetic ordering of the UN structure is explicitly taken into account, for both energetic and transport properties. Solute diffusivities are compared with experimental measurements and the effect of various parameters on the theoretical model is carefully investigated. We find that kinetic correlations are very strong in this system, and that despite atomic migration anisotropy, macroscopic solute diffusivities show limited anisotropy. Our model indicates that the discrepancy between experimental measurements probably results from different irradiation conditions, and hence different defect concentrations.

  8. Unconventional ferromagnetism and transport properties of (In,Mn)Sb dilute magnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Krivoruchko, V.N., E-mail: krivoruc@krivoruc.fti.ac.donetsk.u [Donetsk Physics and Technology Institute NAS of Ukraine, Street R. Luxemburg 72, 83114 Donetsk (Ukraine); Tarenkov, V.Yu.; Varyukhin, D.V.; D' yachenko, A.I. [Donetsk Physics and Technology Institute NAS of Ukraine, Street R. Luxemburg 72, 83114 Donetsk (Ukraine); Pashkova, O.N.; Ivanov, V.A. [N. S. Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31 Leninsky av., 119991 Moscow (Russian Federation)

    2010-04-15

    Narrow-gap higher mobility semiconducting alloys In{sub 1-x}Mn{sub x}Sb were synthesized in polycrystalline form and their magnetic and transport properties have been investigated. Ferromagnetic response in In{sub 0.98}Mn{sub 0.02}Sb was detected by the observation of clear hysteresis loops up to room temperature in direct magnetization measurements. An unconventional (reentrant) magnetization versus temperature behavior has been found. We explained the observed peculiarities within the frameworks of recent models which suggest that a strong temperature dependence of the carrier density is a crucial parameter determining carrier-mediated ferromagnetism of (III,Mn)V semiconductors. The correlation between magnetic states and transport properties of the sample has been discussed. The contact spectroscopy method is used to investigate a band structure of (InMn)Sb near the Fermi level. Measurements of the degree of charge current spin polarization have been carried out using the point contact Andreev reflection (AR) spectroscopy. The AR data are analyzed by introducing a quasiparticle spectrum broadening, which is likely to be related to magnetic scattering in the contact. The AR spectroscopy data argued that at low temperature the sample is decomposed on metallic ferromagnetic clusters with relatively high spin polarization of charge carriers (up to 65% at 4.2 K) within a cluster.

  9. Molecular Dynamics Simulation of the Transport Properties of Molten Transuranic Salt Mixtures

    Science.gov (United States)

    Baty, Austin; McIntyre, Peter; Sattarov, Akhdiyor; Sooby, Elizabeth

    2012-10-01

    The Accelerator Research Laboratory at Texas A&M is proposing a revolutionary design for accelerator-driven subcritical fission in molten salt (ADSMS), a system that destroys the transuranic elements in spent nuclear fuel. The transuranics are the most enduring hazard of nuclear power, since they contain high radiotoxicity and have half-lives of a thousand to a million years. The ADSMS core is fueled by a homogeneous chloride-based molten salt mixture containing the chlorides of the transuranics and NaCl. Knowledge of the density, heat capacity, thermal conductivity, etc. of the salt mixtures is needed to accurately model the complex ADSMS system. There is a lack of experimental data on the density and transport properties of such mixtures. Molecular dynamics simulations using polarizable ion potentials are used to determine the density and heat capacity of these melts as a function of temperature. Green-Kubo methods are employed to calculate the electrical conductivity, thermal conductivity, and viscosity of the salt using the outputs of the model. Results for pure molten salt systems are compared to experimental data when possible to validate the potentials used. Here we discuss potential salt systems, their neutronic behavior, and the calculated transport properties.

  10. Electron transport properties of gallium nitride for microscopic power device modelling

    Energy Technology Data Exchange (ETDEWEB)

    Benbakhti, B [University of Glasgow, Glasgow, Scotland G12 8LT (United Kingdom); Rousseau, M; Soltani, A; Jaeger, J-C De, E-mail: brahim@elec.gla.ac.u [IEMN, Avenue Poincar, Villeneuve dAscq 59652 (France)

    2009-11-15

    The design of power GaN devices has to take into account the impact of temperature on device materials due to highly dissipated power and a consequent large self-heating. The accurate knowledge of transport properties as a function of the lattice temperature is essential in order to make a good thermal management to optimise the device performance. In this paper, accurate expressions describing the main transport properties as function of temperature and electric field for wurtzite GaN have been extracted starting from Monte Carlo simulations and then using a genetic algorithm. In particular, these expressions take into account the abrupt change in electron velocity slope at a low electric field ({approx}20 kV/cm). Using the same methodology, we have determined the temperature dependence of other physical parameters such as the low field mobility, saturation velocity, critical electric field and the corresponding peak velocity in a temperature range of 300 K - 700 K. The results show a very good agreement between the theoretical and experimental values.

  11. 30 CFR 206.359 - How do I determine byproduct transportation allowances?

    Science.gov (United States)

    2010-07-01

    ... MINERALS REVENUE MANAGEMENT PRODUCT VALUATION Geothermal Resources § 206.359 How do I determine byproduct... equipment or the life of the geothermal project which the transportation system services. After you choose... operations data for the transportation system or, if such data are not available, use estimates based on data...

  12. 40 CFR 93.122 - Procedures for determining regional transportation-related emissions.

    Science.gov (United States)

    2010-07-01

    ... or maintenance area VMT on off-network roadways within the urban transportation planning area, and on roadways outside the urban transportation planning area. (b) Regional emissions analysis in serious, severe... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Procedures for determining regional...

  13. Insights into molecular properties of the human monocarboxylate transporter 8 by combining functional with structural information

    Directory of Open Access Journals (Sweden)

    Kleinau Gunnar

    2011-08-01

    Full Text Available Abstract Background The monocarboxylate transporter 8 (MCT8 is a member of the major facilitator superfamily (MFS and transports specificly iodothyronines. MCT8 mutations are the underlying cause of a syndrome of severe X-linked psychomotor retardation known as the Allan-Herndon-Dudley syndrome. This syndrome is characterized by abnormally high T3, low/normal T4 serum levels and slightly elevated serum TSH. To date, more than 25 pathogenic mutations in hMCT8 are known and they are valuable indicators of important regions for structural and functional MCT8 properties. Methods We designed a structural human MCT8 model and studied reported pathogenic missense mutations with focus on the estimation of those amino acid positions which are probably sensitive for substrate transport. Furthermore, assuming similarities between determinants of T3 binding observed in the published crystal structure of the thyroid hormone receptor beta occupied by its ligand T3 and the structural MCT8 model, we explore potential T3 binding sites in the MCT8 substrate channel cavity. Results We found that all known pathogenic missense mutations are located exclusively in the transmembrane helices and to a high degree at conserved residues among the MCT family. Furthermore, mutations either of or to prolines/glycines are located mainly at helices 9-12 and are expected to cause steric clashes or structural misfolding. In contrast, several other mutations are close to the potential substrate channel and affected amino acids are likely involved in the switching mechanism between different transporter conformations. Finally, three potential substrate binding sites are predicted for MCT8. Conclusions Naturally occurring mutations of MCT8 provide molecular insights into protein regions important for protein folding, substrate binding and the switching mechanism during substrate transport. Future studies guided by this information should help to clarify structure

  14. State-to-state kinetics and transport properties of electronically excited N and O atoms

    Science.gov (United States)

    Istomin, V. A.; Kustova, E. V.

    2016-11-01

    A theoretical model of transport properties in electronically excited atomic gases in the state-to-state approach is developed. Different models for the collision diameters of atoms in excited states are discussed, and it is shown that the Slater-like models can be applied for the state-resolved transport coefficient calculations. The influence of collision diameters of N and O atoms with electronic degrees of freedom on the transport properties is evaluated. Different distributions on the electronic energy are considered for the calculation of transport coefficients. For the Boltzmann-like distributions at temperatures greater than 15000 K, an important effect of electronic excitation on the thermal conductivity and viscosity coefficients is found; the coefficients decrease significantly when many electronic states are taken into account. It is shown that under hypersonic reentry conditions the impact of collision diameters on the transport properties is not really important since the populations of high levels behind the shock waves are low.

  15. Improved Flow Property Determination from Nanotomography of Porous Media

    DEFF Research Database (Denmark)

    Jha, Diwaker

    The pore scale morphology of a porous medium determines the fluid transport through that medium. It can be described by parameters, such as porosity, pore size distribution and surface area, which can be computationally determined from synchrotron based X-ray tomography (SXCT) data. The uncertain......The pore scale morphology of a porous medium determines the fluid transport through that medium. It can be described by parameters, such as porosity, pore size distribution and surface area, which can be computationally determined from synchrotron based X-ray tomography (SXCT) data...... methods, the results can become unreliable if the structural disparity between a reconstructed tomogram and a real sample is large. In this thesis, I attempted to decrease this disparity, especially because the samples were natural porous media, such as Bryozoan limestone and North Sea Basin chalk, where...... errors in a small scale study can have profound implications when the results are applied to larger scale systems. The sources of the disparity between a physical sample and tomography data already begin with imaging. As most imaging systems, tomograms are prone to various artifacts. A reconstructed...

  16. Pedometer-determined physical activity and active transport in girls

    Directory of Open Access Journals (Sweden)

    Schofield Grant

    2008-01-01

    Full Text Available Abstract Background It is well established that the risk of insufficient physical activity is greater in girls than in boys, especially during the adolescent years. The promotion of active transport (AT to and from school has been posited as a practical and convenient solution for increasing girls' total daily activity. However, there is limited information describing the associations between AT choices and girls' physical activity across a range of age, ethnic, and socioeconomic groups. The objectives of this study were to (1 investigate physical activity patterns in a large multiethnic sample of female children and adolescents, and to (2 estimate the physical activity associated with AT to and from school. Methods A total of 1,513 girls aged 5–16 years wore sealed multiday memory (MDM pedometers for three weekdays and two weekend days. The ethnic composition of this sample was 637 European (42.1%, 272 Pacific Island (18.0%, 207 East Asian (13.7%, 179 Maori (11.8%, 142 South Asian (9.4%, and 76 from other ethnic groups (5%. Pedometer compliance and school-related AT were assessed by questionnaire. Results Mean weekday step counts (12,597 ± 3,630 were higher and less variable than mean weekend steps (9,528 ± 4,407. A consistent decline in daily step counts was observed with age: after adjustment for ethnicity and SES, girls in school years 9–10 achieved 2,469 (weekday and 4,011 (weekend fewer steps than girls in years 1–2. Daily step counts also varied by ethnicity, with Maori girls the most active and South Asian girls the least active. Overall, 44.9% of participants used AT for school-related travel. Girls who used AT to and from school averaged 1,052 more weekday steps than those who did not use AT. However, the increases in steps associated with AT were significant only in older girls (school years 5–10 and in those of Maori or European descent. Conclusion Our data suggest that adolescent-aged girls and girls of Asian descent are

  17. Transport properties of topological insulators films and nanowires

    Institute of Scientific and Technical Information of China (English)

    Liu Yi; Ma Zheng; Zhao Yan-Fei; Meenakshi Singh; Wang Jian

    2013-01-01

    The last several years have witnessed the rapid developments in the study and understanding of topological insulators.In this review,after a brief summary of the history of topological insulators,we focus on the recent progress made in transport experiments on topological insulator films and nanowires.Some quantum phenomena,including the weak antilocalization,the Aharonov-Bohm effect,and the Shubnikov-de Haas oscillations,observed in these nanostructures are described.In addition,the electronic transport evidence of the superconducting proximity effect as well as an anomalous resistance enhancement in topological insulator/superconductor hybrid structures is included.

  18. INVESTIGATION OF TURBULENCE STRUCTURES AND TURBULENT COUNTER-GRADIENT TRANSPORT PROPERTIES IN STRATIFIED FLOWS

    Institute of Scientific and Technical Information of China (English)

    QIU Xiang

    2006-01-01

    Turbulence structures and turbulent Counter-Gradient Transport(CGT) properties in the stratified flows with a sharp temperature interface are investigated by experimental measurements using LIF and PIV, by LES and by correlation analysis.

  19. Electron transport and electrocatalytic properties of MWCNT/nickel nanocomposites: hydrazine and diethylaminoethanethiol as analytical probes

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-06-01

    Full Text Available This work describes the electron transport and electrocatalytic properties of chemically-synthesized nickel (Ni) and nickel oxide (NiO) nanoparticles supported on multi-walled carbon nanotubes (MWCNT) platforms. Successful modification...

  20. Magnetic and Transport Properties of Ferromagnetic Semiconductor GaDyN Thin Film

    Institute of Scientific and Technical Information of China (English)

    LI Xi-Jun; ZHOU YI-Kai; KIM M.; KIMURA S.; TERAGUCHI N.; EMURA S.; HASEGAWA S.; ASAHI H.

    2005-01-01

    @@ Magnetic properties and temperature dependence of electrical transport properties of rare-earth-metal Dy-doped GaN thin film are experimentally studied with a superconducting quantum interference device magnetometer and van der Pauw method. It was found that this thin nitride film has both semiconductor properties and ferromagnetism from 10K to room temperature. The dopant-band (conducting band due to doping) electron conduction dominates the transport properties of this film at low temperatures. These results indicate that Dy-doped GaN is an n-type ferromagnetic semiconductor at room temperature.

  1. Experimental determination of thermal properties of alluvial soil

    Science.gov (United States)

    Kulkarni, N. G.; Bhandarkar, U. V.; Puranik, B. P.; Rao, A. B.

    2016-12-01

    In the present work, thermal conductivity and specific heat of a particular type of alluvial soil used in brick making in a certain region of India (Karad, Maharashtra State) are experimentally determined for later use in the estimation of ground heat loss in clamp type kilns. These properties are determined simultaneously using the steady-state and the transient temperature data measured in the setup constructed for this purpose. Additionally, physical properties of the soil are experimentally determined for use with six models for the prediction of the thermal conductivity of soil. The predictions from the models are compared with the experimental data. A separate data fitting exercise revealed a small temperature dependence of the soil thermal conductivity on the soil mean temperature.

  2. Physicochemical properties and transport of steroids across Caco-2 cells

    NARCIS (Netherlands)

    Faassen, F.; Kelder, J.; Lenders, J.; Onderwater, R.; Vromans, H.

    2003-01-01

    Purpose. The purpose of this work was to study the relevant physicochemical properties for the absorption of steroids. Methods. Various physicochemical properties of steroids were calculated (molecular weight, ClogP, static polar surface area [PSA], etc.). Within this series of steroids, different p

  3. Direct method for calculating temperature-dependent transport properties

    NARCIS (Netherlands)

    Liu, Y.; Yuan, Z.; Wesselink, R.J.H.; Starikov, A.A.; Schilfgaarde, van M.; Kelly, P.J.

    2015-01-01

    We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calcula

  4. Field scale variability of solute transport parameters and related soil properties

    Directory of Open Access Journals (Sweden)

    B. Lennartz

    1997-01-01

    transport parameters and independently determined soil properties when non-preferential and preferential samples were considered separately in regression analyses. Future work should concentrate to relate integrated parameters such as the infiltration rate or the soil hydraulic functions to solute mobility under different flow situations.

  5. Charge transport properties of metal/metal-phthalocyanine/n-Si structures

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Afzal

    2010-12-16

    In present work the charge transport properties of metal/metal-phthalocyanine/n-Si structures with low (N{sub D} = 4 x 10{sup 14} cm{sup -3}), medium (N{sub D}=1 x 10{sup 16} cm{sup -3}) and high (N{sub D}=2 x 10{sup 19} cm{sup -3}) doped n-Si as injecting electrode and the effect of air exposure of the vacuum evaporated metal-phthalocyanine film in these structures is investigated. The results obtained through temperature dependent electrical characterizations of the structures suggest that in terms of dominant conduction mechanism in the corresponding devices Schottky-type conduction mechanism dominates the charge transport in low-bias region of these devices up to 0.8 V, 0.302 V and 0.15 V in case of low, medium and high doped n-Silicon devices. For higher voltages, in each case of devices, the space-charge-limited conduction, controlled by exponential trap distribution, is found to dominate the charge transport properties of the devices. The interface density of states at the CuPc/n-Si interface of the devices are found to be lower in case of lower work function difference at the CuPc/n-Si interface of the devices. The results also suggest that the work function difference at the CuPc/n-Si interface of these devices causes charge transfer at the interface and these phenomena results in formation of interface dipole. The width of the Schottky depletion region at the CuPc/n-Si interface of these devices is found to be higher with higher work function difference at the interface. The investigation of charge transport properties of Al/ZnPc/medium n-Si and Au/ZnPc/ medium n-Si devices suggest that the Schottky depletion region formed at the ZnPc/n-Si interface of these devices determines the charge transport in the low-bias region of both the devices. Therefore, the Schottky-type (injection limited) and the space-charge-limited (bulk limited) conduction are observed in the low and the high bias regions of these devices, respectively. The determined width of the

  6. Seasonal transport - A study to determine the seasonal effects of transporting fish from the Snake River to optimize a transportation strategy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of this U.S. Army Corps of Engineers (USACE) - funded study that began in 2004 is to determine if the smolt-to-adult return rates (SARs), transport/in-river...

  7. Temperature dependent dielectric properties and ion transportation in solid polymer electrolyte for lithium ion batteries

    Science.gov (United States)

    Sengwa, R. J.; Dhatarwal, Priyanka; Choudhary, Shobhna

    2016-05-01

    Solid polymer electrolyte (SPE) film consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrix with lithium tetrafluroborate (LiBF4) as dopant ionic salt and poly(ethylene glycol) (PEG) as plasticizer has been prepared by solution casting method followed by melt pressing. Dielectric properties and ionic conductivity of the SPE film at different temperatures have been determined by dielectric relaxation spectroscopy. It has been observed that the dc ionic conductivity of the SPE film increases with increase of temperature and also the decrease of relaxation time. The temperature dependent relaxation time and ionic conductivity values of the electrolyte are governed by the Arrhenius relation. Correlation observed between dc conductivity and relaxation time confirms that ion transportation occurs with polymer chain segmental dynamics through hopping mechanism. The room temperature ionic conductivity is found to be 4 × 10-6 S cm-1 which suggests the suitability of the SPE film for rechargeable lithium batteries.

  8. Physical property determinations of short chain chlorinated paraffins

    Energy Technology Data Exchange (ETDEWEB)

    Drouillard, K.G.D. [Univ. of Manitoba, Winnipeg, Manitoba (Canada). Dept. of Soil Science; Hiebert, T.; Friesen, K.J. [Univ. of Winnipeg, Manitoba (Canada). Dept. of Chemistry; Muir, D.C.G. [Freshwater Inst., Winnipeg, Manitoba (Canada)

    1995-12-31

    Chlorinated paraffins (CP) are chlorinated derivatives of n-alkanes commonly utilized in commercial formulations of flame retardants, plasticizers and high pressure lubricants. Recent reviews on CPs have expressed concern regarding the potential toxicity and carcinogenic properties of these compounds. Of the various classes of CPs, short chain compounds (carbon chain lengths 10 to 13) appear to pose the greatest risk. There is little data available concerning key physical properties of CPs required to assess their environmental behavior and mobility. In this study, water solubilities, dissolved organic matter water partition coefficients (K{sub DOM}) and Henry`s Law constants were determined for short chain chlorinated paraffins by generator column, apparent solubility enhancement and gas-purging techniques. Water solubilities were determined for synthesized, isolated products of polychlorinated decanes, undecanes and dodecanes. Solubilities at 25 C were on the order of 2 to 140 {micro}g/L for tetra- to hexachlorodecane products. The Henry`s Law constants for tetra- and pentachlorodecane were determined to be 6.6 {+-} 0.6 and 3.5 {+-} 0.6 Pa{center_dot}m{sup 3}{center_dot}mol{sup {minus}1} respectively. Relationships between carbon chain length and degree of chlorination on the determined physical properties will be discussed.

  9. DETERMINATION OF THE AGR-1 CAPSULE TO FPMS SPECTROMETER TRANSPORT VOLUMES FROM LEADOUT FLOW TEST DATA

    Energy Technology Data Exchange (ETDEWEB)

    J. K. Hartwell; J. B. Walter; D. M. Scates; M. W. Drigert

    2007-05-01

    The AGR-1 experiment is a fueled multiple-capsule irradiation experiment being conducted in the Advanced Test Reactor (ATR) in support of the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program. A flow experiment conducted during the AGR-1 irradiation provided data that included the effect of flow rate changes on the decay of a short-lived radionuclide (23Ne). This data has been analyzed to determine the capsule-specific downstream transport volume through which the capsule effluents must pass before arrival at the fission product monitoring system spectrometers. These resultant transport volumes when coupled with capsule outlet flow rates determine the transport times from capsule-to-detector. In this work an analysis protocol is developed and applied in order to determine capsule-specific transport volumes to precisions of better than +/- 7%.

  10. Exercise gas transport determinants in elderly normotensive and hypertensive humans.

    Science.gov (United States)

    Petrella, R J; Cunningham, D A; Paterson, D H

    1999-01-01

    This study examined the effect of the phenylalkylamine calcium channel blocker verapamil, on resting left ventricular (LV) function and O2 uptake rate (VO2) during exercise at maximal and submaximal work rates. Nine older hypertensive (71 years; OH), 10 older sedentary normotensive (69 years; OS), 10 older active (71 years; OA) and 10 young (24 years; Y) individuals volunteered. Studies were completed in the control condition and 4-6 h following 240 mg verapamil SR per os. Resting LV systolic (fractional shortening; FS) and diastolic (early: late (E/A) flow velocity ratio and isovolumic relaxation time (IVRT) were measured by Doppler echocardiography. Maximal oxygen uptake (VO2,max) and, on subsequent test days, four transitions to and from a 6 min square wave exercise perturbation at a sub-anaerobic threshold intensity of 40 W (OH, OS, OA) or 100 W (Y) for determination of VO2 kinetics were performed on a cycle ergometer. Breath-by-breath VO2 transients were fitted with a monoexponential equation, starting at phase 2 of the response, while heart rate (HR) was fitted from phase 1, for the determination of the time constant of VO2 (tau VO2) and HR (tau HR). Baseline left ventricular FS was significantly greater in the OS (32%), OA (34%) and Y (34%) than in the OH (23%) groups, while E/A was significantly greater in the OA (1.16) and Y (2.34) than in the OH (0.9) and OS (0.82) groups (P < 0.05). Baseline VO2,max was higher and tau VO2 faster in the young (41.4 ml kg-1 min-1; 25.2 s) than in the older groups and in the OA (28.8 ml kg-1 min-1; 44.3 s) than in both OH (20.8 ml kg-1 min-1; 71.3 s) and OS (22.0 ml kg-1 min-1; 59.5 s) groups (P < 0.05). Heart rate kinetics showed similar differences to VO2 kinetics among the groups. After verapamil, no significant changes in FS, E/A or IVRT were observed in the OA and Y groups. In the OH group, FS (32%) and E/A (1.15) increased while IVRT decreased significantly (from 0.103 to 0.07; P < 0.05). In the OS group, only E

  11. EFFECT OF SANDSTONE ANISOTROPY ON ITS HEAT AND MOISTURE TRANSPORT PROPERTIES

    Directory of Open Access Journals (Sweden)

    Jan Fořt

    2015-09-01

    Full Text Available Each type of natural stone has its own geological history, formation conditions, different chemical and mineralogical composition, which influence its possible anisotropy. Knowledge in the natural stones anisotropy represents crucial information for the process of stone quarrying, its correct usage and arrangement in building applications. Because of anisotropy, many natural stones exhibit different heat and moisture transport properties in various directions. The main goal of this study is to analyse several anisotropy indices and their effect on heat transport and capillary absorption. For the experimental determination of the anisotropy effect, five types of sandstone coming from different operating quarries in the Czech Republic are chosen. These materials are often used for restoration of culture heritage monuments as well as for other building applications where they are used as facing slabs, facade panels, decoration stones, paving, etc. For basic characterization of studied materials, determination of their bulk density, matrix density and total open porosity is done. Chemical composition of particular sandstones is analysed by X-Ray Fluorescence. Anisotropy is examined by the non-destructive measurement of velocity of ultrasonic wave propagation. On the basis of ultrasound testing data, the relative anisotropy, total anisotropy and anisotropy coefficient are calculated. Then, the measurement of thermal conductivity and thermal diffusivity in various directions of samples orientation is carried out. The obtained results reveal significant differences between the parameters characterizing the heat transport in various directions, whereas these values are in accordance with the indices of anisotropy. Capillary water transport is described by water absorption coefficient measured using a sorption experiment, which is performed for distilled water and 1M NaCl water solution.  The measured data confirm the effect of anisotropy which is

  12. Investigation of mass transport properties of microfibrillated cellulose (MFC) films

    DEFF Research Database (Denmark)

    Minelli, Matteo; Baschetti, Marco Giacinti; Doghieri, Ferruccio

    2010-01-01

    sorption experiments confirmed the hydrophilic character of these cellulosic materials and showed a dual effect of glycerol which reduced the water uptake at low water activity while enhancing it at high relative humidity. The water diffusion in dry samples was remarkably slow for a porous material...... was observed in permeation experiments. Dry MFC films showed excellent oxygen barrier properties; however, a dramatic decrease in these properties was observed when the water content in the samples was increased....

  13. Understanding hopping transport and thermoelectric properties of conducting polymers

    Science.gov (United States)

    Ihnatsenka, S.; Crispin, X.; Zozoulenko, I. V.

    2015-07-01

    We calculate the conductivity σ and the Seebeck coefficient S for the phonon-assisted hopping transport in conducting polymers poly(3,4-ethylenedioxythiophene) or PEDOT, experimentally studied by Bubnova et al. [J. Am. Chem. Soc. 134, 16456 (2012)], 10.1021/ja305188r. We use the Monte Carlo technique as well as the semianalytical approach based on the transport energy concept. We demonstrate that both approaches show a good qualitative agreement for the concentration dependence of σ and S . At the same time, we find that the semianalytical approach is not in a position to describe the temperature dependence of the conductivity. We find that both Gaussian and exponential density of states (DOS) reproduce rather well the experimental data for the concentration dependence of σ and S giving similar fitting parameters of the theory. The obtained parameters correspond to a hopping model of localized quasiparticles extending over 2-3 monomer units with typical jumps over a distance of 3-4 units. The energetic disorder (broadening of the DOS) is estimated to be 0.1 eV. Using the Monte Carlo calculation we reproduce the activation behavior of the conductivity with the calculated activation energy close to the experimentally observed one. We find that for a low carrier concentration a number of free carriers contributing to the transport deviates strongly from the measured oxidation level. Possible reasons for this behavior are discussed. We also study the effect of the dimensionality on the charge transport by calculating the Seebeck coefficient and the conductivity for the cases of three-, two-, and one-dimensional motion.

  14. Size Effects in Transport Properties of PbSe Thin Films

    Science.gov (United States)

    Rogacheva, E. I.; Nashchekina, O. N.; Menshikova, S. I.

    2017-07-01

    This paper presents an overview and analysis of our earlier obtained experimental results on the dependences of kinetic properties of single PbSe quantum wells and PbSe-based superlattices on the PbSe layer thickness d. The observed oscillatory character of these dependences is attributed to quantum size effects due to electron or hole confinement in quantum wells. Some general regularities and factors that determine the character of these quantum size effects are established. The influence of the oxidation processes and doping on the d-dependences of the transport properties is revealed. A periodic change in the conductivity type related to quantum size oscillations is detected. It is shown that the experimentally determined values of the oscillation period Δ d are in good agreement with the results of theoretical calculations based on the model of a rectangular quantum well with infinitely high walls, taking into account the dependence of the Fermi energy ɛ F on d and the availability of subbands below ɛ F. It is established that the Δ d value for the superlattices is practically equal to the Δ d value observed for the single PbSe thin film.

  15. Systematic characterization of porosity and mass transport and mechanical properties of porous polyurethane scaffolds.

    Science.gov (United States)

    Wang, Yu-Fu; Barrera, Carlos M; Dauer, Edward A; Gu, Weiyong; Andreopoulos, Fotios; Huang, C-Y Charles

    2017-01-01

    One of the key challenges in porous scaffold design is to create a porous structure with desired mechanical function and mass transport properties which support delivery of biofactors and development of function tissue substitute. In recent years, polyurethane (PU) has become one of the most popular biomaterials in various tissue engineering fields. However, there are no studies fully investigating the relations between porosity and both mass transport and mechanical properties of PU porous scaffolds. In this paper, we fabricated PU scaffolds by combining phase inversion and salt (sodium chloride) leaching methods. The tensile and compressive moduli were examined on PU scaffolds fabricated with different PU concentrations (25%, 20% and 15% w/v) and salt/PU weight ratios (9/1, 6/1, 3/1 and 0/1). The mass transport properties of PU scaffolds including hydraulic permeability and glucose diffusivity were also measured. Furthermore, the relationships between the porosity and mass transport and mechanical properties of porous PU scaffold were systemically investigated. The results demonstrated that porosity is a key parameter which governs both mass transport and mechanical properties of porous PU scaffolds. With similar pore sizes, the mass transport and mechanical properties of porous PU scaffold can be described as single functions of porosity regardless of initial PU concentration. The relationships between scaffold porosity and properties can be utilized to facilitate porous PU scaffold fabrication with specific mass transport and mechanical properties. The systematic approach established in this study can be applied to characterization of other biomaterials for scaffold design and fabrication.

  16. Mechanical property determination of high conductivity metals and alloys

    Science.gov (United States)

    Harrod, D. L.; Vandergrift, E.; France, L.

    1973-01-01

    Pertinent mechanical properties of three high conductivity metals and alloys; namely, vacuum hot pressed grade S-200E beryllium, OFHC copper and beryllium-copper alloy no. 10 were determined. These materials were selected based on their possible use in rocket thrust chamber and nozzle hardware. They were procured in a form and condition similar to that which might be ordered for actual hardware fabrication. The mechanical properties measured include (1) tension and compression stress strain curves at constant strain rate (2) tensile and compressive creep, (3) tensile and compressive stress-relaxation behavior and (4) elastic properties. Tests were conducted over the temperature range of from 75 F to 1600 F. The resulting data is presented in both graphical and tabular form.

  17. Determination of optical properties by variation of boundary conditions

    Science.gov (United States)

    Nickell, Stephan; Essenpreis, Matthias; Kraemer, U.; Kohl-Bareis, Matthias; Boecker, Dirk

    1998-01-01

    Propagation of photons in multiple scattering media depends on absorbing and scattering properties as well as the boundary conditions of the semi-infinite medium. A new method is shown that makes use of differences in boundary conditions to determine the optical properties. Induced are these different conditions by varying the reflectivity of a sensor head. We describe the influence of the change in reflectivity with the common diffusion theory. By building a ratio between the spatially-resolved diffuse reflectance under different boundary conditions it is possible to calculate the optical properties of homogeneous phantoms. Due to optical heterogeneities in living tissue, limitations of the method was observed, which restricts the application to in vivo measurements.

  18. Determination of physical properties of fibrous thermal insulation

    Directory of Open Access Journals (Sweden)

    Jeandel G.

    2012-10-01

    Full Text Available The objective of this study is to characterize both experimentally and theoretically, conductive and radiative heat transfer within polyester batting. This material is derived from recycled bottles (PET with fibres of constant diameters. Two other mineral and plant fibrous insulation materials, (glass wool and hemp wool are also characterized for comparative purposes. To determine the overall thermophysical properties of the tested materials, heat flux measurement are carried out using a device developed in house. The radiative properties of the material are determined by an inverse method based on measurements of transmittance and reflectance using a FTIR spectrometer and by solving the equation of radiative heat transfer. These measures are compared to results of numerical simulations.

  19. Determination of physical properties of fibrous thermal insulation

    Science.gov (United States)

    Tilioua, A.; Libessart, L.; Joulin, A.; Lassue, S.; Monod, B.; Jeandel, G.

    2012-10-01

    The objective of this study is to characterize both experimentally and theoretically, conductive and radiative heat transfer within polyester batting. This material is derived from recycled bottles (PET) with fibres of constant diameters. Two other mineral and plant fibrous insulation materials, (glass wool and hemp wool) are also characterized for comparative purposes. To determine the overall thermophysical properties of the tested materials, heat flux measurement are carried out using a device developed in house. The radiative properties of the material are determined by an inverse method based on measurements of transmittance and reflectance using a FTIR spectrometer and by solving the equation of radiative heat transfer. These measures are compared to results of numerical simulations.

  20. Thermodynamical and microscopic properties of turbulent transport in the edge plasma

    Science.gov (United States)

    Ghendrih, Ph; Norscini, C.; Hasenbeck, F.; Dif-Pradalier, G.; Abiteboul, J.; Cartier-Michaud, T.; Garbet, X.; Grandgirard, V.; Marandet, Y.; Sarazin, Y.; Tamain, P.; Zarzoso, D.

    2012-12-01

    Edge plasma turbulence modelled with 2D interchange is shown to exhibit convective transport at the microscale level. This transport property is related to avalanche like transport in such a flux-driven system. Correlation functions and source modulation are used to analyse the transport properties but do not allow one to recover the Fick law that must characterise the system at large scales. Coarse graining is then introduced to average out the small scales in order to recover the Fick law. One finds that the required space averaging is comparable to the system size while the time averaging is comparable to the confinement time. The system is then reduced to a single reservoir such that transport is characterised by a single scalar, either the diffusion coefficient of the Fick law or a characteristic evolution time constant.

  1. Influence of deformation on the fluid transport properties of salt rocks

    NARCIS (Netherlands)

    Peach, C.J.

    1991-01-01

    While the fluid transport properties of rocks are well understood under hydrostatic conditions, little is known regarding these properties in rocks undergoing crystal plastic deformation. However, such data are needed as input in the field of radioactive waste disposal in salt formations. They are a

  2. Influence of deformation on the fluid transport properties of salt rocks

    NARCIS (Netherlands)

    Peach, C.J.

    1991-01-01

    While the fluid transport properties of rocks are well understood under hydrostatic conditions, little is known regarding these properties in rocks undergoing crystal plastic deformation. However, such data are needed as input in the field of radioactive waste disposal in salt formations. They are a

  3. Determination of Tensile Properties of Polymers at High Strain Rates

    Directory of Open Access Journals (Sweden)

    Major Z.

    2010-06-01

    Full Text Available In the field of high rate testing of polymers the measured properties are highly dependent on the applied methodology. Hence, the test setup as whole but in particular also the geometrical type of specimen plays a decisive role. The widely used standard for the determination of tensile properties of polymers (ISO527-2 was extended by a novel standard (ISO18872:2007, which is targeted on the determination of tensile properties at high strain rates. In this standard also a novel specimen shape is proposed. Hand in hand with the introduction of new specimen geometry the question of comparability arises. To point out the differences in stress-strain response of the ISO18872 specimen and the ISO527-2 multipurpose specimen tensile tests over a wide loading rate range were conducted in this paper. A digital image correlation system in combination with a high speed camera was used to characterize the local material behaviour. Different parameters like nominal stress, true stress, nominal strain, true strain as well as volumetric strain were determined and used to compare the two specimen geometries.

  4. Determination of deposited flux and energy of sputtered tungsten atoms on every stages of transport in HiPIMS discharge

    Science.gov (United States)

    Desecures, M.; de Poucques, L.; Bougdira, J.

    2017-02-01

    A time-resolved tunable diode-laser (DL) induced fluorescence (TR-TDLIF) technique has been used to identify different populations of atoms (on different stages of transport) to determine their corresponding deposited energy and flux. The temporal dimension permits the splitting of the processes of sputtering during the discharge and particles transport in the post-discharge where atoms and flux velocity distribution functions (AVDF, FVDF) of each population were measured varying the discharge parameters (power, voltage, pressure, and distance from target). Tungsten (W) was chosen, being an interesting case in terms of sputtered atom transport, considering its weight which implies weak changes of directivity or energy transfer after collisions with the buffer gas. The high temporal and spectral resolutions of TR-TDLIF are the keys for the distinction of the atoms populations and the stage corresponding to the transition from the ballistic to diffusive regime of transport was observed for the first time and named quasi-diffusive regime. Thus, the ability to dissociate populations of atoms and to determine their deposited flux and energy may be of great interest to adjust film properties as desired for applications.

  5. Role of atomic terraces and steps in the electron transport properties of epitaxial graphene grown on SiC

    Directory of Open Access Journals (Sweden)

    H. Kuramochi

    2012-03-01

    Full Text Available Thermal decomposition of vicinal SiC substrates with self-organized periodic nanofacets is a promising method to produce large graphene sheets toward the commercial exploitation of graphene's superior electronic properties. The epitaxial graphene films grown on vicinal SiC comprise two distinct regions of terrace and step; and typically exhibit anisotropic electron transport behavior, although limited areas in the graphene film showed ballistic transport. To evaluate the role of terraces and steps in electron transport properties, we compared graphene samples with terrace and step regions grown on 4H-SiC(0001. Arrays of field effect transistors were fabricated on comparable graphene samples with their channels parallel or perpendicular to the nanofacets to identify the source of measured reduced mobility. Minimum conductivity and electron mobility increased with the larger proportional terrace region area; therefore, the terrace region has superior transport properties to step regions. The measured electron mobility in the terrace region, ∼1000 cm2/Vs, is 10 times larger than that in the step region, ∼100 cm2/Vs. We conclusively determine that parasitic effects originate in regions of graphene that grow over step edges in 4H-SiC(0001.

  6. Microsphere-chain waveguides: Focusing and transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Kenneth W., E-mail: kallen62@uncc.edu; Astratov, Vasily N., E-mail: astratov@uncc.edu [Department of Physics and Optical Science, Center for Optoelectronics and Optical Communications, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001 (United States); Air Force Research Laboratory, Sensors Directorate, Wright Patterson AFB, Ohio 45433 (United States); Darafsheh, Arash; Abolmaali, Farzaneh [Department of Physics and Optical Science, Center for Optoelectronics and Optical Communications, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001 (United States); Mojaverian, Neda; Limberopoulos, Nicholaos I. [Air Force Research Laboratory, Sensors Directorate, Wright Patterson AFB, Ohio 45433 (United States); Lupu, Anatole [Institut d' Electronique Fondamentale, UMR 8622 CNRS, Universite Paris-Sud XI, 91405 Orsay (France)

    2014-07-14

    It is shown that the focusing properties of polystyrene microsphere-chain waveguides (MCWs) formed by sufficiently large spheres (D ≥ 20λ, where D is the sphere diameter and λ is the wavelength of light) scale with the sphere diameter as predicted by geometrical optics. However, this scaling behavior does not hold for mesoscale MCWs with D ≤ 10λ resulting in a periodical focusing with gradually reducing beam waists and in extremely small propagation losses. The observed effects are related to properties of nanojet-induced and periodically focused modes in such structures. The results can be used for developing focusing microprobes, laser scalpels, and polarization filters.

  7. Transport Properties of the Tomato Fruit Tonoplast : III. Temperature Dependence of Calcium Transport.

    Science.gov (United States)

    Joyce, D C; Cramer, G R; Reid, M S; Bennett, A B

    1988-12-01

    Calcium transport into tomato (Lycopersicon esculentum Mill, cv Castlemart) fruit tonoplast vesicles was studied. Calcium uptake was stimulated approximately 10-fold by MgATP. Two ATP-dependent Ca(2+) transport activities could be resolved on the basis of sensitivity to nitrate and affinity for Ca(2+). A low affinity Ca(2+) uptake system (K(m) > 200 micromolar) was inhibited by nitrate and ionophores and is thought to represent a tonoplast localized H(+)/Ca(2+) antiport. A high affinity Ca(2+) uptake system (K(m) = 6 micromolar) was not inhibited by nitrate, had reduced sensitivity to ionophores, and appeared to be associated with a population of low density endoplasmic reticulum vesicles that contaminated the tonoplast-enriched membrane fraction. Arrhenius plots of the temperature dependence of Ca(2+) transport in tomato membrane vesicles showed a sharp increase in activation energy at temperatures below 10 to 12 degrees C that was not observed in red beet membrane vesicles. This low temperature effect on tonoplast Ca(2+)/H(+) antiport activity could only by partially ascribed to an effect of low temperature on H(+)-ATPase activity, ATP-dependent H(+) transport, passive H(+) fluxes, or passive Ca(2+) fluxes. These results suggest that low temperature directly affects Ca(2+)/H(+) exchange across the tomato fruit tonoplast, resulting in an apparent change in activation energy for the transport reaction. This could result from a direct effect of temperature on the Ca(2+)/H(+) exchange protein or by an indirect effect of temperature on lipid interactions with the Ca(2+)/H(+) exchange protein.

  8. Transport properties of partially ionized and unmagnetized plasmas

    Science.gov (United States)

    Magin, Thierry E.; Degrez, Gérard

    2004-10-01

    This work is a comprehensive and theoretical study of transport phenomena in partially ionized and unmagnetized plasmas by means of kinetic theory. The pros and cons of different models encountered in the literature are presented. A dimensional analysis of the Boltzmann equation deals with the disparity of mass between electrons and heavy particles and yields the epochal relaxation concept. First, electrons and heavy particles exhibit distinct kinetic time scales and may have different translational temperatures. The hydrodynamic velocity is assumed to be identical for both types of species. Second, at the hydrodynamic time scale the energy exchanged between electrons and heavy particles tends to equalize both temperatures. Global and species macroscopic fluid conservation equations are given. New constrained integral equations are derived from a modified Chapman-Enskog perturbative method. Adequate bracket integrals are introduced to treat thermal nonequilibrium. A symmetric mathematical formalism is preferred for physical and numerical standpoints. A Laguerre-Sonine polynomial expansion allows for systems of transport to be derived. Momentum, mass, and energy fluxes are associated to shear viscosity, diffusion coefficients, thermal diffusion coefficients, and thermal conductivities. A Goldstein expansion of the perturbation function provides explicit expressions of the thermal diffusion ratios and measurable thermal conductivities. Thermal diffusion terms already found in the Russian literature ensure the exact mass conservation. A generalized Stefan-Maxwell equation is derived following the method of Kolesnikov and Tirskiy. The bracket integral reduction in terms of transport collision integrals is presented in Appendix for the thermal nonequilibrium case. A simple Eucken correction is proposed to deal with the internal degrees of freedom of atoms and polyatomic molecules, neglecting inelastic collisions. The authors believe that the final expressions are

  9. Transport Properties of III-N Hot Electron Transistors

    Science.gov (United States)

    Suntrup, Donald J., III

    Unipolar hot electron transistors (HETs) represent a tantalizing alternative to established bipolar transistor technologies. During device operation electrons are injected over a large emitter barrier into the base where they travel along the device axis with very high velocity. Upon arrival at the collector barrier, high-energy electrons pass over the barrier and contribute to collector current while low-energy electrons are quantum mechanically reflected back into the base. Designing the base with thickness equal to or less than the hot electron mean free path serves to minimize scattering events and thus enable quasi-ballistic operation. Large current gain is achieved by increasing the ratio of transmitted to reflected electrons. Although III-N HETs have undergone substantial development in recent years, there remain ample opportunities to improve key device metrics. In order to engineer improved device performance, a deeper understanding of the operative transport physics is needed. Fortunately, the HET provides fertile ground for studying several prominent electron transport phenomena. In this thesis we present results from several studies that use the III-N HET as both emitter and analyzer of hot electron momentum states. The first provides a measurement of the hot electron mean free path and the momentum relaxation rate in GaN; the second relies on a new technique called electron injection spectroscopy to investigate the effects of barrier height inhomogeneity in the emitter. To supplement our analysis we develop a comprehensive theory of coherent electron transport that allows us to model the transfer characteristics of complex heterojunctions. Such a model provides a theoretical touchstone with which to compare our experimental results. While these studies are of potential interest in their own right, we interpret the results with an eye toward improving next-generation device performance.

  10. FORTRAN 4 computer program for calculation of thermodynamic and transport properties of complex chemical systems

    Science.gov (United States)

    Svehla, R. A.; Mcbride, B. J.

    1973-01-01

    A FORTRAN IV computer program for the calculation of the thermodynamic and transport properties of complex mixtures is described. The program has the capability of performing calculations such as:(1) chemical equilibrium for assigned thermodynamic states, (2) theoretical rocket performance for both equilibrium and frozen compositions during expansion, (3) incident and reflected shock properties, and (4) Chapman-Jouguet detonation properties. Condensed species, as well as gaseous species, are considered in the thermodynamic calculation; but only the gaseous species are considered in the transport calculations.

  11. Corresponding-states principle and its practice thermodynamic, transport and surface properties of fluids

    CERN Document Server

    Xiang, Hong Wei

    2005-01-01

    The corresponding-states principle helps the understanding and calculating of thermodynamic, transport, and surface properties of substances in various states, required by our modern lifestyle. The Corresponding-States Principle and its Practice: Thermodynamic, Transport and Surface Properties of Fluids describes the origins and applications of the principle from a universal point of view with comparisons to experimental data where possible. It uses the universal theory to explain present theories. Emphasis is on the properties of pure systems, and the corresponding-states theory can also be e

  12. Optical and transport properties of complex molecular systems

    OpenAIRE

    2009-01-01

    Esta Tesis presenta el estudio de las propiedades ópticas y de transporte de sistemas de baja dimensionalidad a través de modelos de enlace fuerte. Nuestro trabajo se centra en dos tipos de sistemas: agregados moleculares lineales y moléculas de ADN.En los Capítulos 2, 3 y 4 se estudian las propiedades de localización de un Hamiltoniano de Frenkel desordenado unidimensional. El desorden se introduce en las energías de sitio y es correlacionado de largo alcance. Para correlaciones fuertes, se ...

  13. Electronic transport properties of graphene doped by gallium

    Science.gov (United States)

    Mach, J.; Procházka, P.; Bartošík, M.; Nezval, D.; Piastek, J.; Hulva, J.; Švarc, V.; Konečný, M.; Kormoš, L.; Šikola, T.

    2017-10-01

    In this work we present the effect of low dose gallium (Ga) deposition (graphene grown by chemical vapor deposition. In situ graphene transport measurements performed with a graphene field-effect transistor structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 electrons per one Ga atom, while the further deposition and Ga cluster formation results in removing electrons from graphene (less n-doping). The experimental results are supported by the density functional theory calculations and explained as a consequence of distinct interaction between graphene and Ga atoms in case of individual atoms, layers, or clusters.

  14. Correlation of Crystalline Structure with Magnetic and Transport Properties of Glass-Coated Microwires

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2017-02-01

    Full Text Available We overviewed the correlation between the structure, magnetic and transport properties of magnetic microwires prepared by the Taylor-Ulitovsky method involving rapid quenching from the melt and drawing of the composite (metallic core, glass coated wire. We showed that this method can be useful for the preparation of different families of magnetic microwires: soft magnetic microwires displaying Giant magnetoimpedance (GMI effect, semi-hard magnetic microwires, microwires with granular structure exhibiting Giant Magnetoresistance (GMR effect and Heusler-type microwires. Magnetic and transport properties of magnetic microwires depend on the chemical composition of metallic nucleus and on the structural features (grain size, precipitating phases of prepared microwires. In all families of crystalline microwires, their structure, magnetic and transport properties are affected by internal stresses induced by the glass coating, depending on the quenching rate. Therefore, properties of glass-coated microwires are considerably different from conventional bulk crystalline alloys.

  15. Electrochemical Approach for Analyzing Electrolyte Transport Properties and Their Effect on Protonic Ceramic Fuel Cell Performance.

    Science.gov (United States)

    Danilov, Nikolay; Lyagaeva, Julia; Vdovin, Gennady; Medvedev, Dmitry; Demin, Anatoly; Tsiakaras, Panagiotis

    2017-08-16

    The design and development of highly conductive materials with wide electrolytic domain boundaries are among the most promising means of enabling solid oxide fuel cells (SOFCs) to demonstrate outstanding performance across low- and intermediate-temperature ranges. While reducing the thickness of the electrolyte is an extensively studied means for diminishing the total resistance of SOFCs, approaches involving an improvement in the transport behavior of the electrolyte membranes have been less-investigated. In the present work, a strategy for analyzing the electrolyte properties and their effect on SOFC output characteristics is proposed. To this purpose, a SOFC based on a recently developed BaCe0.5Zr0.3Dy0.2O3-δ proton-conducting ceramic material was fabricated and tested. The basis of the strategy consists of the use of traditional SOFC testing techniques combined with the current interruption method and electromotive force measurements with a modified polarization-correction assessment. This allows one to determine simultaneously such important parameters as maximal power density; ohmic and polarization resistances; average ion transport numbers; and total, ionic, and electronic film conductivities and their activation energies. The proposed experimental procedure is expected to expand both fundamental and applied basics that could be further adopted to improve the technology of electrochemical devices based on proton-conducting electrolytes.

  16. Electron transport properties of bis[2-(2-hydroxyphenyl)-pyridine]beryllium investigated by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yanping; Chen, Jiangshan; Huang, Jinying; Ma, Dongge, E-mail: mdg1014@ciac.jl.cn, E-mail: dongls@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Changchun 130022 (China); Dong, Lisong, E-mail: mdg1014@ciac.jl.cn, E-mail: dongls@ciac.jl.cn [Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Changchun 130022 (China); Chen, Hui [Department of Science, Shenyang University of Chemical Technology, Shenyang 110142 (China)

    2014-06-14

    The electron transport properties of bis[2-(2-hydroxyphenyl)-pyridine] beryllium (Bepp{sub 2}) are investigated by impedance spectroscopy over a frequency range of 10 Hz to 13 MHz. The Cole-Cole plots demonstrate that the Bepp{sub 2}-based device can be represented by a single parallel resistance R{sub p} and capacitance C{sub p} network with a series resistance R{sub s}. The current-voltage characteristics and the variation of R{sub p} with applied bias voltage indicate the electron conduction of space-charge-limited current with exponential trap distributions in Bepp{sub 2}. It can be seen that the electron mobility exhibits strong field-dependence in low electric field region and almost saturate in high electric field region. It is experimentally found that Bepp{sub 2} shows dispersion transport and becomes weak as the electric field increases. The activation energy is determined to be 0.043 eV by temperature-dependent conductivity, which is consistent with the result obtained from the temperature-dependent current density characteristics. The electron mobility reaches the orders of 10{sup −6}–10{sup −5} cm{sup 2} V{sup −1} s{sup −1}, depending on the electric field.

  17. Tailoring the thermal and electrical transport properties of graphene films by grain size engineering

    Science.gov (United States)

    Ma, Teng; Liu, Zhibo; Wen, Jinxiu; Gao, Yang; Ren, Xibiao; Chen, Huanjun; Jin, Chuanhong; Ma, Xiu-Liang; Xu, Ningsheng; Cheng, Hui-Ming; Ren, Wencai

    2017-02-01

    Understanding the influence of grain boundaries (GBs) on the electrical and thermal transport properties of graphene films is essentially important for electronic, optoelectronic and thermoelectric applications. Here we report a segregation-adsorption chemical vapour deposition method to grow well-stitched high-quality monolayer graphene films with a tunable uniform grain size from ~200 nm to ~1 μm, by using a Pt substrate with medium carbon solubility, which enables the determination of the scaling laws of thermal and electrical conductivities as a function of grain size. We found that the thermal conductivity of graphene films dramatically decreases with decreasing grain size by a small thermal boundary conductance of ~3.8 × 109 W m-2 K-1, while the electrical conductivity slowly decreases with an extraordinarily small GB transport gap of ~0.01 eV and resistivity of ~0.3 kΩ μm. Moreover, the changes in both the thermal and electrical conductivities with grain size change are greater than those of typical semiconducting thermoelectric materials.

  18. Transport properties of the fluid produced at Relativistic Heavy-Ion Collider

    Indian Academy of Sciences (India)

    Rajeev S Bhalerao

    2010-08-01

    It is by now well known that the relativistic heavy-ion collisions at RHIC, BNL have produced a strongly interacting fluid with remarkable properties, among them the lowest ever observed ratio of the coefficient of shear viscosity to entropy density. Arguments based on ideas from the string theory, in particular the AdS/CFT correspondence, led to the conjecture – now known to be violated – that there is an absolute lower limit 1/4 on the value of this ratio. Causal viscous hydrodynamics calculations together with the RHIC data have put an upper limit on this ratio, a small multiple of 1/4, in the relevant temperature regime. Less well-determined is the ratio of the coefficient of bulk viscosity to entropy density. These transport coefficients have also been studied non-perturbatively in the lattice QCD framework, and perturbatively in the limit of high-temperature QCD. Another interesting transport coefficient is the coefficient of diffusion which is also being studied in this context. In this paper some of these recent developments are reviewed and then the opportunities presented by the anticipated LHC data are discussed, for the general nuclear physics audience.

  19. Pore-space distribution and transport properties of an andesitic intrusion

    Science.gov (United States)

    Jamtveit, Bjørn; Krotkiewski, Marcin; Kobchenko, Maya; Renard, Francois; Angheluta, Luiza

    2014-08-01

    The pore structure of magmatic rocks records processes operating during magma solidification and cooling. It has first order effects on the petrophysical properties of the magmatic rocks, and also influences mass transfer and mineral reactions during subsequent metamorphism or weathering. Here, the pore space characteristics of an andesitic sill intrusion were determined by multiscale resolution computed X-ray microtomography (μ-CT), and the 3D structure was used for transport modeling. Unaltered andesite has a power law distribution of pore volumes over a range of five orders of magnitude. The probability distribution function (PDF) scales with the inverse square of the pore volume (V), PDF∝V-2. This scaling behavior is attributed to the coalescence of pores at crystal-melt boundaries. Large pores are concentrated on the outer margins of amphibole and plagioclase phenocrystals. Incipient weathering of the andesite is associated with preferential growth of weathering products in the largest pores. This can be explained by a model in which diffusion of external components into the porous andesite is controlled by a random network of grain boundaries and/or microfractures. This network preferentially links the larger pores to the system boundaries and it is the major fluid transport pathway, confining incipient weathering into a small fraction of the rock volume only.

  20. Model Of Determining Amount Of City Transport Optimal City In Bandung

    Directory of Open Access Journals (Sweden)

    Aviasti Aviasti

    2016-09-01

    Full Text Available The research conducted is to make the model of determining the optimal transportation fleet in Bandung City, to overcome the imbalance between the number of available fleet and the number of passengers in need. This research type is quantitative with case study of two city transportation trajectory in the route of Sadang Serang Caringin and Riung Bandung Dago trajectory which at the time of preliminary research is categorized not optimal. To determine the optimal number of urban transport fleets, there are several variables associated with this include: number of passengers (P, fleet volume / frequency (F, vehicle capacity (C, cycle time (CTABA, load factor ( LF, and headway (H. The results showed that the number of public transport fleet for the route Dago - Riung Bandung and Sadang Serang - Caringin currently too much does not match the needs of the meaning is not optimal

  1. Studies of Transport Properties of Fractures: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephen R. Brown

    2006-06-30

    We proposed to study several key factors controlling the character and evolution of fracture system permeability and transport processes. We suggest that due to surface roughness and the consequent channeling in single fractures and in fracture intersections, the tendency of a fracture system to plug up, remain permeable, or for permeability to increase due to chemical dissolution/precipitation conditions will depend strongly on the instantaneous flow channel geometry. This geometry will change as chemical interaction occurs, thus changing the permeability through time. To test this hypothesis and advance further understanding toward a predictive capability, we endeavored to physically model and analyze several configurations of flow and transport of inert and chemically active fluids through channels in single fractures and through fracture intersections. This was an integrated program utilizing quantitative observations of fractures and veins in drill core, quantitative and visual observations of flow and chemical dissolution and precipitation within replicas of real rough-walled fractures and fracture intersections, and numerical modeling via lattice Boltzmann methods.

  2. Electrical Transport Properties of Polymorphic MoS2.

    Science.gov (United States)

    Kim, Jun Suk; Kim, Jaesu; Zhao, Jiong; Kim, Sungho; Lee, Jin Hee; Jin, Youngjo; Choi, Homin; Moon, Byoung Hee; Bae, Jung Jun; Lee, Young Hee; Lim, Seong Chu

    2016-08-23

    The engineering of polymorphs in two-dimensional layered materials has recently attracted significant interest. Although the semiconducting (2H) and metallic (1T) phases are known to be stable in thin-film MoTe2, semiconducting 2H-MoS2 is locally converted into metallic 1T-MoS2 through chemical lithiation. In this paper, we describe the observation of the 2H, 1T, and 1T' phases coexisting in Li-treated MoS2, which result in unusual transport phenomena. Although multiphase MoS2 shows no transistor-gating response, the channel resistance decreases in proportion to the temperature, similar to the behavior of a typical semiconductor. Transmission electron microscopy images clearly show that the 1T and 1T' phases are randomly distributed and intervened with 2H-MoS2, which is referred to as the 1T and 1T' puddling phenomenon. The resistance curve fits well with 2D-variable range-hopping transport behavior, where electrons hop over 1T domains that are bounded by semiconducting 2H phases. However, near 30 K, electrons hop over charge puddles. The large temperature coefficient of resistance (TCR) of multiphase MoS2, -2.0 × 10(-2) K(-1) at 300 K, allows for efficient IR detection at room temperature by means of the photothermal effect.

  3. Bayesian estimation of the hydraulic and solute transport properties of a small-scale unsaturated soil column

    Directory of Open Access Journals (Sweden)

    Moreira Paulo H. S.

    2016-03-01

    Full Text Available In this study the hydraulic and solute transport properties of an unsaturated soil were estimated simultaneously from a relatively simple small-scale laboratory column infiltration/outflow experiment. As governing equations we used the Richards equation for variably saturated flow and a physical non-equilibrium dual-porosity type formulation for solute transport. A Bayesian parameter estimation approach was used in which the unknown parameters were estimated with the Markov Chain Monte Carlo (MCMC method through implementation of the Metropolis-Hastings algorithm. Sensitivity coefficients were examined in order to determine the most meaningful measurements for identifying the unknown hydraulic and transport parameters. Results obtained using the measured pressure head and solute concentration data collected during the unsaturated soil column experiment revealed the robustness of the proposed approach.

  4. METHODOLOGY FOR DETERMINATION OF ECONOMIC LOSSES AT COORDINATED REGULATION OF TRANSPORT-PEDESTRIAN FLOWS

    OpenAIRE

    2010-01-01

    The paper presents some peculiar features of the developed methodology for determination of economic losses at coordinated regulation of transport and pedestrian flow movement. Preconditions for introduction of pre-signals on light objects which raise efficiency of coordinated control over transport flows are considered separately in the paper. The paper proposes to estimate the coordinated regulation by such criterion as minimization of economic, ecological and emergency losses. Basic princi...

  5. Method of determining an electrical property of a test sample

    DEFF Research Database (Denmark)

    2010-01-01

    A method of obtaining an electrical property of a test sample, comprising a non-conductive area and a conductive or semi-conductive test area, byperforming multiple measurements using a multi-point probe. The method comprising the steps of providing a magnetic field having field lines passing...... each tip, selecting one tip to be a current source positioned between conductive tips being used for determining a voltage in the test sample, performing a first measurement, moving the probe and performing a second measurement, calculating on the basis of the first and second measurement...... perpendicularly through the test area, bringing the probe into a first position on the test area, the conductive tips of the probe being in contact with the test area, determining a position for each tip relative to the boundary between the non- conductive area and the test area, determining distances between...

  6. Transport properties of melanosomes along microtubules interpreted by a tug-of-war model with loose mechanical coupling.

    Directory of Open Access Journals (Sweden)

    Sebastián Bouzat

    Full Text Available In this work, we explored theoretically the transport of organelles driven along microtubules by molecular motors of opposed polarities using a stochastic model that considers a Langevin dynamics for the cargo, independent cargo-motor linkers and stepping motion for the motors. It has been recently proposed that the stiffness of the motor plays an important role when multiple motors collectively transport a cargo. Therefore, we considered in our model the recently reported values for the stiffness of the cargo-motor linker determined in living cells (∼0.01 pN/nm, which is significantly lower than the motor stiffness obtained in in vitro assays and used in previous studies. Our model could reproduce the multimodal velocity distributions and typical trajectory characteristics including the properties of the reversions in the overall direction of motion observed during melanosome transport along microtubules in Xenopus laevis melanophores. Moreover, we explored the contribution of the different motility states of the cargo-motor system to the different modes of the velocity distributions and could identify the microscopic mechanisms of transport leading to trajectories compatible with those observed in living cells. Finally, by changing the attachment and detachment rates, the model could reproduce the different velocity distributions observed during melanosome transport along microtubules in Xenopus laevis melanophores stimulated for aggregation and dispersion. Our analysis suggests that active tug-of-war processes with loose mechanical coupling can account for several aspects of cargo transport along microtubules in living cells.

  7. Suitable experimental design for determination of auxin polar transport in space using a spacecraft.

    Science.gov (United States)

    Shimazu, T; Miyamoto, K; Hoson, T; Kamisaka, S; Ueda, J

    2000-03-01

    It is necessary to establish a suitable experimental design for the determination of auxin (indole-3-acetic acid: IAA) polar transport in space using a spacecraft in concerning with the role of gravity. Problems in space experiments are as follows: I) Selection of suitable plant species; II) Preservation of integrity of plant segments for activities of auxin polar transport; III) Stop of auxin polar transport of the segments after the transport experiment in space. Segments of etiolated pea epicotyls and etiolated maize coleoptiles showed relatively high activities of auxin polar transport among dicotyledonous and monocotyledonous plants tested, respectively. The activities decreased dramatically when the segments were pre-stored at 25 degrees C only for 1 day. On the other hand, the storage at low temperature (5 degrees C) in the presence of antioxidants or chelating agents, especially EGTA, maintained relatively high activities of auxin polar transport in pea epicotyl segments. Low temperature (5 degrees C) substantially inhibited the activity of auxin polar transport. Based on the results in this study, a suitable experimental design for the space experiment of auxin polar transport using a spacecraft is also proposed.

  8. Microstructural and transport properties of superconducting FeTe0.65Se0.35 crystals

    Science.gov (United States)

    Sivakov, A. G.; Bondarenko, S. I.; Prokhvatilov, A. I.; Timofeev, V. P.; Pokhila, A. S.; Koverya, V. P.; Dudar, I. S.; Link, S. I.; Legchenkova, I. V.; Bludov, A. N.; Monarkha, V. Yu; Gawryluk, D. J.; Pietosa, J.; Berkowski, M.; Diduszko, R.; Puzniak, R.; Wisniewski, A.

    2017-01-01

    The issue concerning the nature and the role of microstructural inhomogeneities in iron chalcogenide superconducting crystals of FeTe0.65Se0.35 and their correlation with transport properties of this system was addressed. The presented data demonstrate that chemical disorder originating from the kinetics of the crystal growth process significantly influences the superconducting properties of an Fe-Te-Se system. Transport measurements of the transition temperature and critical current density performed for microscopic bridges allow us to deduce the local properties of a superconductor with microstructural inhomogeneities, and significant differences were noted. The variances observed in the local properties were explained as a consequence of weak superconducting links existing in the studied crystals. The results confirm that the inhomogeneous spatial distribution of ions and small hexagonal symmetry nanoscale regions with nanoscale phase separation also seem to enhance the superconductivity in this system with respect to the values of the critical current density. Magnetic measurements performed in order to determine, in an alternative way, the values of the critical current density, as well as to find the relaxation rate and to check the scaling of the pinning force, confirm the conclusions drawn from the transport measurements.

  9. Desvenlafaxine succinate identifies novel antagonist binding determinants in the human norepinephrine transporter.

    Science.gov (United States)

    Mason, John N; Deecher, Darlene C; Richmond, Rhonda L; Stack, Gary; Mahaney, Paige E; Trybulski, Eugene; Winneker, Richard C; Blakely, Randy D

    2007-11-01

    Desvenlafaxine succinate (DVS) is a recently introduced antagonist of the human norepinephrine and serotonin transporters (hNET and hSERT, respectively), currently in clinical development for use in the treatment of major depressive disorder and vasomotor symptoms associated with menopause. Initial evaluation of the pharmacological properties of DVS (J Pharmacol Exp Ther 318:657-665, 2006) revealed significantly reduced potency for the hNET expressed in membranes compared with whole cells when competing for [(3)H]nisoxetine (NIS) binding. Using hNET in transfected human embryonic kidney-293 cells, this difference in potency for DVS at sites labeled by [(3)H]NIS was found to distinguish DVS, the DVS analog rac-(1-[1-(3-chloro-phenyl)-2-(4-methylpiperazin-1-yl)-ethyl]cyclohexanol (WY-46824), methylphenidate, and the cocaine analog 3beta-(4-iodophenyl)tropane-2beta-carboxylic acid methyl ester (RTI-55) from other hNET antagonists, such as NIS, mazindol, tricyclic antidepressants, and cocaine. These differences seem not to arise from preparation-specific perturbations of ligand intrinsic affinity or antagonist-specific surface trafficking but rather from protein conformational alterations that perturb the relationships between distinct hNET binding sites. In an initial search for molecular features that differentially define antagonist binding determinants, we document that Val148 in hNET transmembrane domain 3 selectively disrupts NIS binding but not that of DVS.

  10. Impact of carbonation on the durability of cementitious materials: water transport properties characterization

    Directory of Open Access Journals (Sweden)

    Le Bescop P.

    2013-07-01

    Full Text Available Within the context of long-lived intermediate level radioactive waste geological disposal, reinforced concrete would be used. In service life conditions, the concrete structures would be subjected to drying and carbonation. Carbonation relates to the reaction between carbon dioxide (CO2 and the main hydrates of the cement paste (portlandite and C-S-H. Beyond the fall of the pore solution pH, indicative of steel depassivation, carbonation induces mineralogical and microstructural changes (due to portlandite and C-S-H dissolution and calcium carbonate precipitation. This results in the modification of the transport properties, which can impact the structure durability. Because concrete durability depends on water transport, this study focuses on the influence of carbonation on water transport properties. In fact, the transport properties of sound materials are known but they still remain to be assessed for carbonated ones. An experimental program has been designed to investigate the transport properties in carbonated materials. Four hardened cement pastes, differing in mineralogy, are carbonated in an accelerated carbonation device (in controlled environmental conditions at CO2 partial pressure of about 3%. Once fully carbonated, all the data needed to describe water transport, using a simplified approach, will be evaluated.

  11. Determination of thermal properties of composting bulking materials.

    Science.gov (United States)

    Ahn, H K; Sauer, T J; Richard, T L; Glanville, T D

    2009-09-01

    Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric heat capacity of 12 compost bulking materials were determined in this study. Thermal properties were determined at varying bulk densities (1, 1.3, 1.7, 2.5, and 5 times uncompacted bulk density), particle sizes (ground and bulk), and water contents (0, 20, 50, 80% of water holding capacity and saturated condition). For the water content at 80% of water holding capacity, saw dust, soil compost blend, beef manure, and turkey litter showed the highest thermal conductivity (K) and volumetric heat capacity (C) (K: 0.12-0.81 W/m degrees C and C: 1.36-4.08 MJ/m(3) degrees C). Silage showed medium values at the same water content (K: 0.09-0.47 W/m degrees C and C: 0.93-3.09 MJ/m(3) degrees C). Wheat straw, oat straw, soybean straw, cornstalks, alfalfa hay, and wood shavings produced the lowest K and C values (K: 0.03-0.30 W/m degrees C and C: 0.26-3.45 MJ/m(3) degrees C). Thermal conductivity and volumetric heat capacity showed a linear relationship with moisture content and bulk density, while thermal diffusivity showed a nonlinear relationship. Since the water, air, and solid materials have their own specific thermal property values, thermal properties of compost bulking materials vary with the rate of those three components by changing water content, bulk density, and particle size. The degree of saturation was used to represent the interaction between volumes of water, air, and solids under the various combinations of moisture content, bulk density, and particle size. The first order regression models developed in this paper represent the relationship between degree of saturation and volumetric heat capacity (r=0.95-0.99) and thermal conductivity (r=0.84-0.99) well. Improved

  12. Transport properties of graphene under periodic and quasiperiodic magnetic superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei-Tao, E-mail: luweitao@lyu.edu.cn [School of Science, Linyi University, 276005 Linyi (China); Institute of Condensed Matter Physics, Linyi University, 276005 Linyi (China); Wang, Shun-Jin [Department of Physics, Sichuan University, 610064 Chengdu (China); Wang, Yong-Long; Jiang, Hua [School of Science, Linyi University, 276005 Linyi (China); Institute of Condensed Matter Physics, Linyi University, 276005 Linyi (China); Li, Wen [School of Science, Linyi University, 276005 Linyi (China)

    2013-08-15

    We study the transmission of Dirac electrons through the one-dimensional periodic, Fibonacci, and Thue–Morse magnetic superlattices (MS), which can be realized by two different magnetic blocks arranged in certain sequences in graphene. The numerical results show that the transmission as a function of incident energy presents regular resonance splitting effect in periodic MS due to the split energy spectrum. For the quasiperiodic MS with more layers, they exhibit rich transmission patterns. In particular, the transmission in Fibonacci MS presents scaling property and fragmented behavior with self-similarity, while the transmission in Thue–Morse MS presents more perfect resonant peaks which are related to the completely transparent states. Furthermore, these interesting properties are robust against the profile of MS, but dependent on the magnetic structure parameters and the transverse wave vector.

  13. Electrical Transport Properties of Carbon Nanotube Metal-Semiconductor Heterojunction

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-10-01

    Carbon nanotubes (CNTs) have been proved to have promising applicability in various fields of science and technology. Their fascinating mechanical, electrical, thermal, optical properties have caught the attention of today’s world. We have discussed here the great possibility of using CNTs in electronic devices. CNTs can be both metallic and semiconducting depending on their chirality. When two CNTs of different chirality are joined together via topological defects, they may acquire rectifying diode property. We have joined two tubes of different chiralities through circumferential Stone-Wales defects and calculated their density of states by nearest neighbor tight binding approximation. Transmission function is also calculated to analyze whether the junctions can be used as electronic devices. Different heterojunctions are modeled and analyzed in this study. Internal stresses in the heterojunctions are also calculated by molecular dynamics simulation.

  14. Determination of corneal image-forming properties from corneal topography.

    Science.gov (United States)

    Maloney, R K; Bogan, S J; Waring, G O

    1993-01-01

    Keratometry provides useful information about the cornea's image-forming properties, such as corneal astigmatism, but is inaccurate on irregular corneas. Quantitative corneal topographic information is now obtainable on irregular corneas, but is difficult for the clinician to interpret. We developed a method to determine the spherical power, astigmatism, and topographic irregularity of a cornea by finding the best-fit spherocylinder that was closest to its measured topography. Keratometric measurements and two videokeratographs were gathered prospectively on 262 normal and abnormal corneas. The best-fit measurements of spherical power, astigmatism, and topographic irregularity were reproducible with one standard deviation of 0.75 diopter or better; agreement with keratometric measurements in normal eyes was good (0.60 diopter or better). Topographic irregularity averaged 0.1 diopter on precision spheres, 0.4 diopter on 146 normal eyes, 0.8 diopter on 29 eyes after radial keratotomy, 2.0 diopters on 58 eyes after penetrating keratoplasty, and 3.0 diopters on 29 eyes with advanced keratoconus. We conclude the following: basic corneal image-forming properties can be measured from videokeratographs; the properties can be determined, by our methods, on irregular corneas in which keratometry is unreliable; and topographic irregularity provides a measure of irregular astigmatism.

  15. Electrical transport properties of CaB6

    Science.gov (United States)

    Stankiewicz, Jolanta; Sesé, Javier; Balakrishnan, Geetha; Fisk, Zachary

    2014-10-01

    We report results from a systematic electron-transport study in a broad temperature range on 12 CaB6 single crystals. None of the crystals were intentionally doped. The different carrier densities observed presumably arise from slight variations in the Ca:B stoichiometry. In these crystals, the variation of the electrical resistivity and of the Hall effect with temperature can be consistently accounted for by the model we propose, in which B-antisite defects (B atom replacing Ca atom) are "amphoteric." The magnetotransport measurements reveal that most of the samples we have studied are close to a metal-insulator transition at low temperatures. The magnetoresistance changes smoothly from negative—for weakly metallic samples—to positive values—for samples in a localized regime.

  16. Low temperature transport properties of pyrolytic graphite sheet

    Science.gov (United States)

    Nakamura, Sachiko; Miyafuji, Daisuke; Fujii, Takenori; Matsui, Tomohiro; Fukuyama, Hiroshi

    2017-09-01

    We have made thermal and electrical transport measurements of uncompressed pyrolytic graphite sheet (uPGS), a mass-produced thin graphite sheet with various thicknesses between 10 and 100 μ m, at temperatures between 2 and 300 K. Compared to exfoliated graphite sheets like Grafoil, uPGS has much higher conductivities by an order of magnitude because of its high crystallinity confirmed by X-ray diffraction and Raman spectroscopy. This material is advantageous as a thermal link of light weight in a wide temperature range particularly above 60 K where the thermal conductivity is much higher than common thermal conductors such as copper and aluminum alloys. We also found a general relationship between thermal and electrical conductivities in graphite-based materials which have highly anisotropic conductivities. This would be useful to estimate thermal conductance of a cryogenic part made of these materials from its electrical conductance more easily measurable at low temperature.

  17. Reference dataset of volcanic ash physicochemical and optical properties for atmospheric measurement retrievals and transport modelling

    Science.gov (United States)

    Vogel, Andreas; Durant, Adam; Sytchkova, Anna; Diplas, Spyros; Bonadonna, Costanza; Scarnato, Barbara; Krüger, Kirstin; Kylling, Arve; Kristiansen, Nina; Stohl, Andreas

    2016-04-01

    Explosive volcanic eruptions emit up to 50 wt.% (total erupted mass) of fine ash particles (threat for aviation operations. Recent volcanic eruptions, such as the 2010 Icelandic Eyjafjallajökull event, illustrated how volcanic ash can severely impact commercial air traffic. In order to manage the threat, it is important to have accurate forecast information on the spatial extent and absolute quantity of airborne volcanic ash. Such forecasts are constrained by empirically-derived estimates of the volcanic source term and the nature of the constituent volcanic ash properties. Consequently, it is important to include a quantitative assessment of measurement uncertainties of ash properties to provide realistic ash forecast uncertainty. Currently, information on volcanic ash physicochemical and optical properties is derived from a small number of somewhat dated publications. In this study, we provide a reference dataset for physical (size distribution and shape), chemical (bulk vs. surface chemistry) and optical properties (complex refractive index in the UV-vis-NIR range) of a representative selection of volcanic ash samples from 10 different volcanic eruptions covering the full variability in silica content (40-75 wt.% SiO2). Through the combination of empirical analytical methods (e.g., image analysis, Energy Dispersive Spectroscopy, X-ray Photoelectron Spectroscopy, Transmission Electron Microscopy and UV/Vis/NIR/FTIR Spectroscopy) and theoretical models (e.g., Bruggeman effective medium approach), it was possible to fully capture the natural variability of ash physicochemical and optical characteristics. The dataset will be applied in atmospheric measurement retrievals and atmospheric transport modelling to determine the sensitivity to uncertainty in ash particle characteristics.

  18. Bottom-up processing and low temperature transport properties of polycrystalline SnSe

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Zhen-Hua; Wei, Kaya; Lewis, Hutton [Department of Physics, University of South Florida, Tampa, FL 33620 (United States); Martin, Joshua [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Nolas, George S., E-mail: gnolas@usf.edu [Department of Physics, University of South Florida, Tampa, FL 33620 (United States)

    2015-05-15

    A hydrothermal approach was employed to efficiently synthesize SnSe nanorods. The nanorods were consolidated into polycrystalline SnSe by spark plasma sintering for low temperature electrical and thermal properties characterization. The low temperature transport properties indicate semiconducting behavior with a typical dielectric temperature dependence of the thermal conductivity. The transport properties are discussed in light of the recent interest in this material for thermoelectric applications. The nanorod growth mechanism is also discussed in detail. - Graphical abstract: SnSe nanorods were synthesized by a simple hydrothermal method through a bottom-up approach. Micron sized flower-like crystals changed to nanorods with increasing hydrothermal temperature. Low temperature transport properties of polycrystalline SnSe, after SPS densification, were reported for the first time. This bottom-up synthetic approach can be used to produce phase-pure dense polycrystalline materials for thermoelectrics applications. - Highlights: • SnSe nanorods were synthesized by a simple and efficient hydrothermal approach. • The role of temperature, time and NaOH content was investigated. • SPS densification allowed for low temperature transport properties measurements. • Transport measurements indicate semiconducting behavior.

  19. Determination of magnetic properties of multilayer metallic thin films

    CERN Document Server

    Birlikseven, C

    2000-01-01

    and magnetization measurements were taken. In recent year, Giant Magnetoresistance Effect has been attracting an increasingly high interest. High sensitivity magnetic field detectors and high sensitivity read heads of magnetic media can be named as important applications of these films. In this work, magnetic and electrical properties of single layer and thin films were investigated. Multilayer thin films were supplied by Prof. Dr. A. Riza Koeymen from Texas University. Multilayer magnetic thin films are used especially for magnetic reading and magnetic writing. storing of large amount of information into small areas become possible with this technology. Single layer films were prepared using the electron beam evaporation technique. For the exact determination of film thicknesses, a careful calibration of the thicknesses was made. Magnetic properties of the multilayer films were studied using the magnetization, magnetoresistance measurements and ferromagnetic resonance technique. Besides, by fitting the exper...

  20. Non-equilibrium STLS approach to transport properties of single impurity Anderson model

    Science.gov (United States)

    Rezai, Raheleh; Ebrahimi, Farshad

    2014-04-01

    In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron-electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current-voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron-electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U2 IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior.

  1. Investigation of boron modified graphene nanostructures; optoelectronic properties of graphene nanoparticles and transport properties of graphene nanosheets

    Science.gov (United States)

    Armaković, Stevan; Armaković, Sanja J.

    2016-11-01

    In this work we investigated optoelectronic properties of graphene nanoparticles and transport properties of graphene nanosheets and the consequences on these properties after modifications with boron atoms. Within the framework of density functional theory (DFT) several important optoelectronic quantities have been calculated for graphene nanoparticles: oxidation and reduction potentials, hole and electron reorganization energies, while thermally activated delayed fluorescence was assessed by calculations of energy separation between the lowest excited singlet (S1) and triplet (T1) state, Δ E (S1 -T1) . Obtained results show that optoelectronic properties of graphene nanoparticles are significantly improved by the modification with boron atoms and that investigated structures can be considered as a promising organic light emitting diode (OLED) materials. Influence of boron atoms to charge and heat transport properties of graphene nanosheets was investigated as well, employing the self-consistent non-equilibrium Green's functions with DFT. On the other side it is shown that charge transport of graphene nanosheets is not influenced by the introduction of boron atoms, while influence to the phonon subsystem is minimal.

  2. Correlating substituent parameter values to electron transport properties of molecules

    Science.gov (United States)

    Vedova-Brook, Natalie; Matsunaga, Nikita; Sohlberg, Karl

    2004-03-01

    There are a vast number of organic compounds that could be considered for use in molecular electronics. Because of this, the need for efficient and economical screening tools has emerged. We demonstrate that the substituent parameter values ( σ), commonly found in advanced organic chemistry textbooks, correlate strongly with features of the charge migration process, establishing them as useful indicators of electronic properties. Specifically, we report that ab initio derived electronic charge transfer values for 16 different substituted aromatic molecules for molecular junctions correlate to the σ values with a correlation coefficient squared ( R2) of 0.863.

  3. Random lasing in structures with multi-scale transport properties

    CERN Document Server

    Leonetti, Marco

    2013-01-01

    In a random laser (RL), a system possessing in itself both resonator and amplifying medium while lacking of a macroscopic cavity, the feedback is provided by the scattering, which forces light to travel across very long random paths. Here we demonstrate that RL properties may be tuned by the topology of the scattering system retaining unchanged scattering strength and gain efficiency. This is possible in a system based on sparse clusters, possessing two relevant structural lengths: the macroscopic inter cluster separation and the mesoscopic intra-cluster mean free path.

  4. Method for determining transport critical current densities and flux penetration depth in bulk superconductors

    Science.gov (United States)

    Israelsson, Ulf E. (Inventor); Strayer, Donald M. (Inventor)

    1992-01-01

    A contact-less method for determining transport critical current density and flux penetration depth in bulk superconductor material. A compressor having a hollow interior and a plunger for selectively reducing the free space area for distribution of the magnetic flux therein are formed of superconductor material. Analytical relationships, based upon the critical state model, Maxwell's equations and geometrical relationships define transport critical current density and flux penetration depth in terms of the initial trapped magnetic flux density and the ratio between initial and final magnetic flux densities whereby data may be reliably determined by means of the simple test apparatus for evaluating the current density and flux penetration depth.

  5. Oxide-based protonic conductors: Point defects and transport properties

    DEFF Research Database (Denmark)

    Bonanos, N.

    2001-01-01

    that determine the protonic concentrations are considered, with emphasis on the regime of low oxygen partial pressure. The measurement of the thermoelectric power (TEP) and of the H+/D+ isotope effect in conductivity are discussed as a means of characterising the conduction process. (C) 2001 Elsevier Science B...

  6. Transport properties of stripe-ordered high Tc cuprates

    Science.gov (United States)

    Jie, Qing; Han, Su Jung; Dimitrov, Ivo; Tranquada, J. M.; Li, Qiang

    2012-11-01

    Transport measurements provide important characterizations of the nature of stripe order in the cuprates. Initial studies of systems such as La1.6-xNd0.4SrxCuO4 demonstrated the strong anisotropy between in-plane and c-axis resistivities, but also suggested that stripe order results in a tendency towards insulating behavior within the planes at low temperature. More recent work on La2-xBaxCuO4 with x = 1/8 has revealed the occurrence of quasi-two-dimensional superconductivity that onsets with spin-stripe order. The suppression of three-dimensional superconductivity indicates a frustration of the interlayer Josephson coupling, motivating a proposal that superconductivity and stripe order are intertwined in a pair-density-wave state. Complementary characterizations of the low-energy states near the Fermi level are provided by measurements of the Hall and Nernst effects, each revealing intriguing signatures of stripe correlations and ordering. We review and discuss this work.

  7. Spin-polarized quantum transport properties through flexible phosphorene

    Science.gov (United States)

    Chen, Mingyan; Yu, Zhizhou; Xie, Yiqun; Wang, Yin

    2016-10-01

    We report a first-principles study on the tunnel magnetoresistance (TMR) and spin-injection efficiency (SIE) through phosphorene with nickel electrodes under the mechanical tension and bending on the phosphorene region. Both the TMR and SIE are largely improved under these mechanical deformations. For the uniaxial tension (ɛy) varying from 0% to 15% applied along the armchair transport (y-)direction of the phosphorene, the TMR ratio is enhanced with a maximum of 107% at ɛy = 10%, while the SIE increases monotonously from 8% up to 43% with the increasing of the strain. Under the out-of-plane bending, the TMR overall increases from 7% to 50% within the bending ratio of 0%-3.9%, and meanwhile the SIE is largely improved to around 70%, as compared to that (30%) of the flat phosphorene. Such behaviors of the TMR and SIE are mainly affected by the transmission of spin-up electrons in the parallel configuration, which is highly dependent on the applied mechanical tension and bending. Our results indicate that the phosphorene based tunnel junctions have promising applications in flexible electronics.

  8. Transport properties and Stokes-Einstein relation in Al-rich liquid alloys

    Science.gov (United States)

    Jakse, N.; Pasturel, A.

    2016-06-01

    We use ab initio molecular dynamics simulations to study the transport properties and the validity of the Stokes-Einstein relation in Al-rich liquid alloys with Ni, Cu, and Zn as alloying elements. First, we show that the composition and temperature dependence of their transport properties present different behaviors, which can be related to their local structural ordering. Then, we evidence that the competition between the local icosahedral ordering and the local chemical ordering may cause the breakdown of the Stokes-Einstein relation even in the liquid phase. We demonstrate that this breakdown can be captured by entropy-scaling relationships developed by Rosenfeld and using the two-body excess entropy. Our findings provide a unique framework to study the relation between structure, thermodynamics, and dynamics in metallic melts and pave the way towards the explanation of various complex transport properties in metallic melts.

  9. Study on the Electronic Transport Properties of Zigzag GaN Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Li Enling; Wang Xiqiang; Hou Liping; Zhao Danna; Dai Yuanbin [Sciences School, Xi' an University of Technology, Xi' an, China 710054 (China); Wang Xuewen [Electronic Information Science and Technology, Northwest University, Xi' an, China 710068 (China)

    2011-02-01

    The electronic transport properties of zigzag GaN nanotubes (n, 0) (4 {<=} n {<=} 9) have been calculated using the density functional theory and non-equilibrium Green's functions method. Firstly, the density functional theory (DFT) is used to optimize and calculate the electronic structure of GaNNTs (n, 0) (4{<=}n{<=}9). Secondly, DFT and non-equilibrium Green function (NEGF) method are also used to predict the electronic transport properties of GaNNTs two-probe system. The results showed: there is a corresponding relation between the electronic transport properties and the valley of state density of each GaNNT. In addition, the volt-ampere curve of GaNNT is approximately linear.

  10. Transport properties of iron-porphyrin molecule sandwiched between Au surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Hisashi [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)], E-mail: KONDO.Hisashi@nims.go.jp; Kino, Hiori; Nara, Jun [CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Ohno, Takahisa [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); MANA, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2008-09-30

    The transport properties of an iron-porphyrin molecule sandwiched between Au(1 1 1) electrodes are investigated using the non-equilibrium Green's function method based on the density functional theory, and in particular, the dependence on a terminal-atom position is studied. We consider four models for terminal-atom positions. It is found that the transport properties of the junction system are very sensitive to a terminal-atom position. We also find that the contribution of the d-orbitals of the Fe atom to the transport properties around the Fermi energy strongly changes, depending on a terminal-atom position. From these results, we propose a suitable terminal-atom position for the molecular sensor discussed in the other paper.

  11. High field transport properties of InAs/AlGaSb quantum wires

    Science.gov (United States)

    Sasa, S.; Sugihara, T.; Tada, K.; Izumiya, S.; Yamamoto, Y.; Inoue, M.

    1996-09-01

    We demonstrate the successful fabrication of multiple quantum wire structures using InAs/AlGaSb heterostructures and report on their transport properties. We have performed magnetotransport measurements on the various width of the wires ranging between 0.2 and 0.4 μm. One-dimensional transport properties confirmed by magnetic depopulation were observed up to 0.4-μm-wide wires, and the sublevel spacing was as large as 5.9 meV for 0.2-μm-wide wires. This demonstrates the advantageous feature of InAs/AlGaSb heterostructures for realizing quantum devices operating at higher temperatures. High field transport properties also reveal their advantageous features.

  12. Transport Properties of Two-Dimensional Electron Gases in Antiparallel Magnetic-Electric Barrier Structures

    Institute of Scientific and Technical Information of China (English)

    PING Yun-Xia; CHENG Ze

    2006-01-01

    We study theoretically transport properties of two-dimensional electron gases through antiparallel magnetic electric barrier structures. Two kinds of magnetic barrier configurations are employed: one is that the strength of the double δ-function in opposite directions is equal and the other is that the strength is unequal. Similarities and differences of electronic transports are presented. It is found that the transmission and the conductance depend strongly on the shape of the magnetic barrier and the height of the electric barrier. The results indicate that this system does not possess any spin filtering and spin polarization and electron gases can realize perfect resonant tunneling and wave-vector filtering properties. Moreover, the strength of the effect of the inhomogeneous magnetic field on the transport properties is discussed.

  13. Tuning of Transport and Magnetic Properties in Epitaxial LaMnO3+δ Thin Films

    Directory of Open Access Journals (Sweden)

    J. Chen

    2014-01-01

    Full Text Available The effect of compressive strain on the transport and magnetic properties of epitaxial LaMnO3+δ thin films has been investigated. It is found that the transport and magnetic properties of the LaMnO3+δ thin films grown on the LaAlO3 substrates can be tuned by the compressive strain through varying film thickness. And the insulator-metal transition, charge/orbital ordering transition, and paramagnetic-ferromagnetic transition are suppressed by the compressive strain. Consequently, the related electronic and magnetic transition temperatures decrease with an increase in the compressive strain. The present results can be explained by the strain-controlled lattice deformation and the consequent orbital occupation. It indicates that the lattice degree of freedom is crucial for understanding the transport and magnetic properties of the strongly correlated LaMnO3+δ.

  14. Determining adjustment variables for rationalising a design for fleet operation in public passenger transport

    Directory of Open Access Journals (Sweden)

    Carlos Fabián Flórez Valero

    2010-04-01

    Full Text Available This investigation was aimed at establishing aspects leading to adjusting the operational design of public transport fleet operation to make it more profitable for private investors. Data obtained from more than a year’s operation by the Alianza Sat S.A. was used (this being a bus- company alliance grouping about 100 buses from some of Bogotá’s collective transport companies for carrying out the present investigation regarding fleet administration and operation. Simply implementing conventionally-designed routing plans is not enough for rationalising fleet operation, as most public collective transport is not directly operated by companies The Alianza Sat S.A. bus fleet was used for testing hypotheses demonstrating that current operational design for the company’s routes (in Bogotá’s current public transport market conditions leads to reducing the company’s income. The investigation revealed that public pas-senger transport bus fleet revenue can be increased if aspects different to those considered in standard route design methodology are controlled. The investigation has determined alternative rationalisation for operational collective public passenger transport company design regarding adjusting aspects such as the demand pattern, operating scheme, route variability, etc. This will provide an innovative and useful tool for rationalising the operational design of bus routes operating in cities having weak public transport control and excess bus supply.

  15. Charge Transport Properties of Tetrabenz[a,c,h,jl-anthracene Derivatives

    Institute of Scientific and Technical Information of China (English)

    CHEN Zi-Ran; YU Wen-Hao; LI Quan

    2012-01-01

    Charge transport properties of F, OH, OCH3, SH and SCH3-substituted tetra- benz[a,c,h,j]- anthracene derivative molecules have been investigated theoretically at the B3LYP/6-31G** level using Marcus theory. The results showed that at 300 K, the hole or electron transport capability of F or SH-substituted molecules was better obviously than that of OH or OCH3-substituted molecules, The electron transport capability of SCH3-substituted and F or SH-substituted molecules was superior to their hole transport capability, respectively. F, SH or SCH3-substituted tetrabenz[a,c,h,j]-anthracene derivative molecules can be used as electron transport materials.

  16. Effect of Cd ions on transport properties of orthomanganites

    CERN Document Server

    Troyanchuk, I O; Pastushonok, S N

    1998-01-01

    Magnetic and magnetotransport measurements have been used to study the compositional dependence of the electronic properties of the solid solutions La sub 0 sub . sub 7 (Pb sub 0 sub . sub 3 sub - sub x Cd sub x)MnO sub 3 and Nd sub 0 sub . sub 7 (Pb sub 0 sub . sub 3 sub - sub x Cd sub x)MnO sub 3. It was found that these compounds are ferromagnets and have the rhombohedrally or orthorhombically distorted perovskite structure. The substitution of Pb ions by Cd leads to the transition from the metallic to the insulating state. The intermediate compositions exhibit two peaks of the resistivity and magnetoresistance. The high-temperature peak is associated with the Curie temperature whereas there is no magnetic anomaly in the temperature interval of the second peak. We suppose that Cd ions participate in the formation of the narrow impurity band limiting the mobility of charge carriers. (author)

  17. Exceptional transport property in a rolled-up germanium tube

    Science.gov (United States)

    Guo, Qinglei; Wang, Gang; Chen, Da; Li, Gongjin; Huang, Gaoshan; Zhang, Miao; Wang, Xi; Mei, Yongfeng; Di, Zengfeng

    2017-03-01

    Tubular germanium (Ge) resistors are demonstrated by rolling-up thin Ge nanomembranes (NMs, 50 nm in thickness) with electrical contacts. The strain distribution of rolled-up Ge microtubes along the radial direction is investigated and predicted by utilizing micro-Raman scattering spectroscopy with two different excitation lasers. Electrical properties are characterized for both unreleased GeNMs and released/rolled-up Ge microtubes. The conductivities of GeNMs significantly decrease after rolling-up into tubular structures, which can be attributed to surface charging states on the conductance, band bending, and piezo-resistance effect. When illuminated with a light source, facilitated by the suppressed dark current of rolled-up Ge tubes, the corresponding signal-to-noise ratio can be dramatically enhanced compared with that of planar GeNMs.

  18. Electronic transport properties of Ir-decorated graphene.

    Science.gov (United States)

    Wang, Yilin; Xiao, Shudong; Cai, Xinghan; Bao, Wenzhong; Reutt-Robey, Janice; Fuhrer, Michael S

    2015-10-28

    Graphene decorated with 5d transitional metal atoms is predicted to exhibit many intriguing properties; for example iridium adatoms are proposed to induce a substantial topological gap in graphene. We extensively investigated the conductivity of single-layer graphene decorated with iridium deposited in ultra-high vacuum at low temperature (7 K) as a function of Ir concentration, carrier density, temperature, and annealing conditions. Our results are consistent with the formation of Ir clusters of ~100 atoms at low temperature, with each cluster donating a single electronic charge to graphene. Annealing graphene increases the cluster size, reducing the doping and increasing the mobility. We do not observe any sign of an energy gap induced by spin-orbit coupling, possibly due to the clustering of Ir.

  19. Effect of vertical-strain-induced symmetry breaking on transport properties of zigzag graphene nanoribbons

    Science.gov (United States)

    Zou, Dongqing; Zhao, Wenkai; Fang, Changfeng; Cui, Bin; Liu, Desheng

    2017-02-01

    Using density functional theory combined with nonequilibrium Green's function formalism, we investigate the transport properties of zigzag graphene nanoribbons (ZGNRs) under vertical strain. Our calculations show that localized state induced by vertical strain will inhibit the electronic transport of the systems at zero bias, but at nonzero bias, the localized state can enhance the electronic transport behavior if ZGNRs are symmetry with respect to the mid-plane between two edges. This is because the localized state produces an asymmetry electron density distribution which break the current suppression. These findings may be useful for the application of strain-induced ZGNR based molecular devices.

  20. An overview of heavy oil properties and its recovery and transportation methods

    Directory of Open Access Journals (Sweden)

    R. G. Santos

    2014-09-01

    Full Text Available Unconventional oils - mainly heavy oils, extra heavy oils and bitumens - represent a significant share of the total oil world reserves. Oil companies have expressed interest in unconventional oil as alternative resources for the energy supply. These resources are composed usually of viscous oils and, for this reason, their use requires additional efforts to guarantee the viability of the oil recovery from the reservoir and its subsequent transportation to production wells and to ports and refineries. This review describes the main properties of high-viscosity crude oils, as well as compares traditional and emergent methods for their recovery and transportation. The main characteristics of viscous oils are discussed to highlight the oil properties that affect their flowability in the processes of recovery and pipeline transportation. Chemical composition is the starting point for the oil characterization and it has major impact on other properties, including key properties for their dynamics, such as density and viscosity. Next, enhanced oil recovery (EOR methods are presented, followed by a discussion about pipeline and transportation methods. In addition, the main challenges to achieve viable recovery and transportation of unconventional oils are compared for the different alternatives proposed. The work is especially focused on the heavy oils, while other hydrocarbon solid sources, such as oil sands and shale oil, are outside of the scope of this review.

  1. The Effect of Twin Grain Boundary Tuned by Temperature on the Electrical Transport Properties of Monolayer MoS2

    OpenAIRE

    Luojun Du; Hua Yu; Li Xie; Shuang Wu; Shuopei Wang; Xiaobo Lu; Mengzhou Liao; Jianling Meng; Jing Zhao; Jing Zhang; Jianqi Zhu; Peng Chen; Guole Wang; Rong Yang; Dongxia Shi

    2016-01-01

    Theoretical calculation and experimental measurement have shown that twin grain boundary (GB) of molybdenum disulphide (MoS2) exhibits extraordinary effects on transport properties. Precise transport measurements need to verify the transport mechanism of twin GB in MoS2. Here, monolayer molybdenum disulphide with a twin grain boundary was grown in our developed low-pressure chemical vapor deposition (CVD) system, and we investigated how the twin GB affects the electrical transport properties ...

  2. Epitaxial growth and electrical transport properties of La0.5Sr0.5CoO3 thin films prepared by pulsed laser deposition

    Institute of Scientific and Technical Information of China (English)

    李美亚; 熊光成; 王忠烈; 范守善; 赵清太; 林揆训

    1999-01-01

    Epitaxial growth of the La0.5Sr0.5CoO3(LSCO) thin films has been realized on LaAlO3, SrTiO3 and MgO substrates by pulsed laser deposition. The epitaxial growth behavior and the electrical transport properties of these films were studied systematically. The temperature dependencies of the resistivity of the film have been determined. Studies indicate that close dependencies exist between the crystal structures and the electrical transport properties of the epitaxial LSCO films, and that the epitaxial thin films are of low resistivity and metallic conductive features. The epitaxial films deposited on the LaAlO3 substrates at about 700℃ possess the optimal properties compared with the others. Discussions of the dependencies and the mechanisms of the epitaxial structures on the electrical transport properties of the LSCO films have been made.

  3. Determining the population properties of spinning black holes

    Science.gov (United States)

    Talbot, Colm; Thrane, Eric

    2017-07-01

    There are at least two formation scenarios consistent with the first gravitational-wave observations of binary black hole mergers. In field models, black hole binaries are formed from stellar binaries that may undergo common envelope evolution. In dynamic models, black hole binaries are formed through capture events in globular clusters. Both classes of models are subject to significant theoretical uncertainties. Nonetheless, the conventional wisdom holds that the distribution of spin orientations of dynamically merging black holes is nearly isotropic while field-model black holes prefer to spin in alignment with the orbital angular momentum. We present a framework in which observations of black hole mergers can be used to measure ensemble properties of black hole spin such as the typical black hole spin misalignment. We show how to obtain constraints on population hyperparameters using minimal assumptions so that the results are not strongly dependent on the uncertain physics of formation models. These data-driven constraints will facilitate tests of theoretical models and help determine the formation history of binary black holes using information encoded in their observed spins. We demonstrate that the ensemble properties of binary detections can be used to search for and characterize the properties of two distinct populations of black hole mergers.

  4. Determination of Some Physical Properties of Jatropha (Jatropha Curcas Oil

    Directory of Open Access Journals (Sweden)

    Olasheu, T.I

    2015-06-01

    Full Text Available The energy crisis and shortage of fuel emanating from total dependence on mineral oil with resultant socioeconomic problems demand the need to explore the use of renewable energy as alternative. This study evaluates the physical properties Jatropha (Jatropha curcas oil as alternative base oil for lubricant in auto engines. A quantity of 32 kg dried base decorticated seeds of Jatropha was locally obtained. Volume of 4 litres of Jatropha oil was extracted from the seeds using existing hydraulic press machine, while its physical properties was determined through laboratory analytical procedure of American Society for Testing and Materials analytical standard 960-52 (ASTM,D960-52. The properties determined were: viscosity, density, flash point, pour point, melting point, refractive index, specific heat and thermal conductivity. Comparisons of the properties were also made with the standard lubricant (SAE 40 engine oil. The principles of flow theories were employed to develop heat generated equation in terms of temperature, density and viscosity of the oil and a computer program in C++ language was thus written. Sensitivity analysis was performed on the effect of temperature change, (30 oC to 100 oC on value of density and viscosity. The physical properties of Jatropha oil are viscosity (162.8 cst, density (0.920 g/ml, flash point (113oC, pour point (7.7oC, melting point (4 to 5oC, refractive index (1.435, specific heat (0.082 KJ/Kg/K and thermal conductivity (4.250 W/moC. Comparative analysis showed that the values of viscosity, density, thermal conductivity and pour point for Jatropha oil were higher than the values of SAE 40 engine oil while specific heat, flash point and refractive index values of Jatropha oil were less than the values of SAE 40 engine oil. The result showed that the average values for density and viscosity of Jatropha oil were 890.75 Kgm-3 and 0.1385 N.S/m2 . Sensitivity analysis showed that Jatropha oil has highest density and

  5. Fluctuation theory for transport properties in multicomponent mixtures: thermodiffusion and heat conductivity

    DEFF Research Database (Denmark)

    Shapiro, Alexander

    2004-01-01

    The theory of transport properties in multicomponent gas and liquid mixtures, which was previously developed for diffusion coefficients, is extended onto thermodiffusion coefficients and heat conductivities. The derivation of the expressions for transport properties is based on the general...... statistical theory of fluctuations around an equilibrium state. The Onsager matrix of phenomenological coefficients is expressed in terms of the penetration lengths, including the newly introduced penetration length for the energy transfer. As an example, this penetration length is found from the known value...... of the heat conductivity coefficient for ideal gas. (C) 2003 Elsevier B.V. All rights reserved....

  6. Electrical transport properties of graphene on SiO2 with specific surface structures

    OpenAIRE

    Nagashio, K.; Yamashita, T; Nishimura, T.; K. Kita; Toriumi, A.

    2011-01-01

    The mobility of graphene transferred on a SiO2/Si substrate is limited to ~10,000 cm2/Vs. Without understanding the graphene/SiO2 interaction, it is difficult to improve the electrical transport properties. Although surface structures on SiO2 such as silanol and siloxane groups are recognized, the relation between the surface treatment of SiO2 and graphene characteristics has not yet been elucidated. This paper discusses the electrical transport properties of graphene on specific surface stru...

  7. How to determine composite material properties using numerical homogenization

    DEFF Research Database (Denmark)

    Andreassen, Erik; Andreasen, Casper Schousboe

    2014-01-01

    Numerical homogenization is an efficient way to determine effective macroscopic properties, such as the elasticity tensor, of a periodic composite material. In this paper an educational description of the method is provided based on a short, self-contained Matlab implementation. It is shown how t...... cell of the periodic material can take the shape of a square, rectangle, or parallelogram, allowing for all kinds of 2D periodicities. © 2013 Elsevier B.V. All rights reserved.......Numerical homogenization is an efficient way to determine effective macroscopic properties, such as the elasticity tensor, of a periodic composite material. In this paper an educational description of the method is provided based on a short, self-contained Matlab implementation. It is shown how...... the basic code, which computes the effective elasticity tensor of a two material composite, where one material could be void, is easily extended to include more materials. Furthermore, extensions to homogenization of conductivity, thermal expansion, and fluid permeability are described in detail. The unit...

  8. Determination of Quality Properties in Labneh Produced with Probiotic Culture

    Directory of Open Access Journals (Sweden)

    Tuğba Kök Taş

    2014-07-01

    Full Text Available The recent years, functional food market has been dramatically growing due to the increasing number of conscious consumers. More products in the field of functional foods include dairy products. Diversity of functional foods that are very popular in the world are very limited in Turkey. Use of probiotic microorganisms in dairy products are provided positive contribution to public health. Probiotic products are featured in many studies to affect the intestinal immune system, regulating the immune system. The aim of this reseach was to use probiotic starter culture to improve functional properties of Labne that is a very nutritious dairy product and preferred by children and youths. The quality properties (chemical, microbiological and sensorial of Labneh were determined. pH value and lactic acid of Labneh sample with yogurt culture and Labneh sample produced with Lactobacillus acidophilus culture were determined 4.53 and 4.58; 0.52 and 0.53, respectively. Labneh sample containing probiotic culture had 21% fat and 29.38% total solid. Labneh sample with probiotic culture contained 8.97 log cfu/ml as content of L. acidophilus. Result of sensory analyses showed that Labneh sample produced using L. acidophilus had higher taste, odor and texture scores.

  9. A method for determination of the absorption and scattering properties interstitially in turbid media

    Science.gov (United States)

    Dimofte, Andreea; Finlay, Jarod C.; Zhu, Timothy C.

    2005-05-01

    We have developed a method to quickly determine tissue optical properties (absorption coefficient μa and transport scattering coefficient μ's) by measuring the ratio of light fluence rate to source power along a linear channel at a fixed distance (5 mm) from an isotropic point source. Diffuse light is collected by an isotropic detector whose position is determined by a computer-controlled step motor, with a positioning accuracy of better than 0.1 mm. The system automatically records and plots the light fluence rate per unit source power as a function of position. The result is fitted with a diffusion equation to determine μa and μ's. We use an integrating sphere to calibrate each source-detector pair, thus reducing uncertainty of individual calibrations. To test the ability of this algorithm to accurately recover the optical properties of the tissue, we made measurements in tissue simulating phantoms consisting of Liposyn at concentrations of 0.23, 0.53 and 1.14% (μ's = 1.7-9.1 cm-1) in the presence of Higgins black India ink at concentrations of 0.002, 0.012 and 0.023% (μa = 0.1-1 cm-1). For comparison, the optical properties of each phantom are determined independently using broad-beam illumination. We find that μa and μ's can be determined by this method with a standard (maximum) deviation of 8% (15%) and 18% (32%) for μa and μ's, respectively. The current method is effective for samples whose optical properties satisfy the requirement of the diffusion approximation. The error caused by the air cavity introduced by the catheter is small, except when μa is large (μa > 1 cm-1). We presented in vivo data measured in human prostate using this method.

  10. Transport Properties of Complex Oxides: New Ideas and Insights from Theory and Simulation

    Science.gov (United States)

    Benedek, Nicole

    Complex oxides are one of the largest and most technologically important materials families. The ABO3 perovskite oxides in particular display an unparalleled variety of physical properties. The microscopic origin of these properties (how they arise from the structure of the material) is often complicated, but in many systems previous research has identified simple guidelines or `rules of thumb' that link structure and chemistry to the physics of interest. For example, the tolerance factor is a simple empirical measure that relates the composition of a perovskite to its tendency to adopt a distorted structure. First-principles calculations have shown that the tendency towards ferroelectricity increases systematically as the tolerance factor of the perovskite decreases. Can we uncover a similar set of simple guidelines to yield new insights into the ionic and thermal transport properties of perovskites? I will discuss recent research from my group on the link between crystal structure and chemistry, soft phonons and ionic transport in a family of layered perovskite oxides, the Ln2NiO4+δ Ruddlesden-Popper phases. In particular, we show how the lattice dynamical properties of these materials (their tendency to undergo certain structural distortions) can be correlated with oxide ion transport properties. Ultimately, we seek new ways to understand the microscopic origins of complex transport processes and to develop first-principles-based design rules for new materials based on our understanding.

  11. Oligomers Modulate Interfibril Branching and Mass Transport Properties of Collagen Matrices

    Science.gov (United States)

    Whittington, Catherine F.; Brandner, Eric; Teo, Ka Yaw; Han, Bumsoo; Nauman, Eric; Voytik-Harbin, Sherry L.

    2013-01-01

    Mass transport within collagen-based matrices is critical to tissue development, repair, and pathogenesis as well as the design of next generation tissue engineering strategies. This work shows how collagen precursors, specified by intermolecular cross-link composition, provide independent control of collagen matrix mechanical and transport properties. Collagen matrices were prepared from tissue-extracted monomers or oligomers. Viscoelastic behavior was measured in oscillatory shear and unconfined compression. Matrix permeability and diffusivity were measured using gravity-driven permeametry and integrated optical imaging, respectively. Both collagen types showed an increase in stiffness and permeability hindrance with increasing collagen concentration (fibril density); however, different physical property-concentration relationships were noted. Diffusivity wasn’t affected by concentration for either collagen type over the range tested. In general, oligomer matrices exhibited a substantial increase in stiffness and only a modest decrease in transport properties when compared to monomer matrices prepared at the same concentration. The observed differences in viscoelastic and transport properties were largely attributed to increased levels of interfibril branching within oligomer matrices. The ability to relate physical properties to relevant microstructure parameters, including fibril density and interfibril branching, is expected to advance the understanding of cell-matrix signaling as well as facilitate model-based prediction and design of matrix-based therapeutic strategies. PMID:23842082

  12. High-field thermal transports properties of REBCO coated conductors

    CERN Document Server

    Bonura, M

    2015-01-01

    The use of REBCO coated conductors is envisaged for many applications, extending from power cables to high-field magnets. Whatever the case, thermal properties of REBCO tapes play a key role for the stability of superconducting devices. In this work, we present the first study on the longitudinal thermal conductivity (k) of REBCO coated conductors in magnetic fields up to 19 T applied both parallelly and perpendicularly to the thermal-current direction. Copper-stabilized tapes from six industrial manufacturers have been investigated. We show that zero-field k of coated conductors can be calculated with an accuracy of ‡ 15% from the residual resistivity ratio of the stabilizer and the Cu/non-Cu ratio. Measurements performed at high fields have allowed us to evaluate the consistency of the procedures generally used for estimating in-field k in the framework of the Wiedemann-Franz law from an electrical characterization of the materials. In-field data are intended to provide primary ingredients for the ...

  13. Structure and transport properties of polymer grafted nanoparticles

    KAUST Repository

    Goyal, Sushmit

    2011-01-01

    We perform molecular dynamics simulations on a bead-spring model of pure polymer grafted nanoparticles (PGNs) and of a blend of PGNs with a polymer melt to investigate the correlation between PGN design parameters (such as particle core concentration, polymer grafting density, and polymer length) and properties, such as microstructure, particle mobility, and viscous response. Constant strain-rate simulations were carried out to calculate viscosities and a constant-stress ensemble was used to calculate yield stresses. The PGN systems are found to have less structural order, lower viscosity, and faster diffusivity with increasing length of the grafted chains for a given core concentration or grafting density. Decreasing grafting density causes depletion effects associated with the chains leading to close contacts between some particle cores. All systems were found to shear thin, with the pure PGN systems shear thinning more than the blend; also, the pure systems exhibited a clear yielding behavior that was absent in the blend. Regarding the mechanism of shear thinning at the high shear rates examined, it was found that the shear-induced decrease of Brownian stresses and increase in chain alignment, both correlate with the reduction of viscosity in the system with the latter being more dominant. A coupling between Brownian stresses and chain alignment was also observed wherein the non-equilibrium particle distribution itself promotes chain alignment in the direction of shear. © 2011 American Institute of Physics.

  14. Magneto-optical transport properties of monolayer WSe2

    Science.gov (United States)

    Tahir, M.; Vasilopoulos, P.

    2016-07-01

    The recent experimental realization of a high quality WSe2 leads to the possibility of magneto-optical measurements and the manipulation of the spin and valley degrees of freedom. We study the influence of the very strong spin-orbit coupling and of the anisotropic lifting of the valley pseudospin degeneracy on its magnetotransport properties. The energy spectrum of WSe2 is derived and discussed in the presence of a perpendicular magnetic field B . Correspondingly we evaluate the magneto-optical Hall conductivity and the optical longitudinal conductivity as functions of the frequency, magnetic field, and Fermi energy. They are strongly influenced by the field B and the strong spin splitting. The former exhibits valley polarization and the latter beatings of oscillations. The magneto-optical responses can be tuned in two different regimes: the microwave-to-terahertz regime and the visible-frequency one. The absorption peaks involving the n =0 LL appear in between these two regimes and show a magnetic control of the spin and valley splittings. We also evaluate the power absorption spectrum.

  15. Investigations of electrical transport properties of individual carbon nanotubes with nanoprober

    Science.gov (United States)

    Feng, Wei; Hayama, Kazumi; Akinaga, Hiroyuki

    2016-06-01

    We investigated and discussed quantitatively the transport properties of individual multiwalled (MW) carbon nanotubes (CNTs) by four-terminal measurement using a nanoprobing system. The homogeneity of the CNT was visibly examined using the electron beam absorbed current function of the nanoprober. The observed ohmic properties of the current-voltage characteristics and metallic transport properties of the CNTs proved that reliable contact of four probes was achieved on the outermost shell of MWCNTs. The experimental methodology was validated for the intrinsic properties of individual CNTs. Lower resistance per unit length was evaluated for thicker CNT. The measured resistance per unit length was lower than those reported by other researchers, but higher than ideally expected.

  16. DETERMINED MODEL FOR COORDINATED REGULATION OF MOTOR TRANSPORT MOVEMENT ON HIGHWAY WITH T-SHAPE CROSSROADS

    Directory of Open Access Journals (Sweden)

    V. N. Shut

    2009-01-01

    Full Text Available The paper examines variants of higher control efficiency in respect of road traffic by creating coordinated regulation  with the help of a determined module. Model application conditions have been determined for specific traffic situations with due account of transport-pedestrian load. The paper contains proposals for the model optimization directed on reduction of  motor vehicle delay in front of the in-traffic light  stop-line along the main highway direction.

  17. Transport timescales and tracer properties in the extratropical UTLS

    Directory of Open Access Journals (Sweden)

    P. Hoor

    2010-05-01

    Full Text Available A comprehensive evaluation of seasonal backward trajectories initialized in the Northern Hemisphere lowermost stratosphere (LMS has been performed to investigate the origin of air parcels and the main mechanisms determining characteristic structures in H2O and CO within the LMS. In particular we explain the fundamental role of the transit time since last tropopause crossing (tTST for the chemical structure of the LMS as well as the feature of the extra-tropical tropopause transition layer (ExTL as identified from CO profiles. The distribution of H2O in the background LMS above Θ=320 K and 340 K in northern winter and summer, respectively, is found to be governed mainly by the saturation mixing ratio, which in turn is determined by the Lagrangian Cold Point (LCP encountered by each trajectory. Most of the backward trajectories from this region in the LMS experienced their LCP in the tropics and sub-tropics. The transit time since crossing the tropopause from the troposphere to the stratosphere (tTST is independent of the H2O value of the air parcel. TST often occurs 20 days after trajectories have encountered their LCP. CO, on the other hand, depends strongly on tTST due to its finite lifetime. The ExTL as identified from CO measurements is then explained as a layer of air just above the tropopause, which on average encountered TST fairly recently.

  18. Formulating gels for decreased mucociliary transport using rheologic properties: Polyacrylic acids

    OpenAIRE

    Shah, Ankur J.; Donovan, Maureen D.

    2007-01-01

    The purpose of these studies was to identify the rheologic properties of polyacrylic acid gels necessary for optimal reductions in mucociliary clearance. The mucociliary transport of 2 bioadhesive polyacrylic acid polymers, polycarbophil and carbopol, was assessed in vitro by measuring their clerance rates across explants of ciliated bovine tracheal tissue. The viscoelastic properties of polymer gels were measured in the presence of mucus using controlled stress rheometry. Combinations of app...

  19. The Arabidopsis MTP8 transporter determines the localization of manganese and iron in seeds.

    Science.gov (United States)

    Chu, Heng-Hsuan; Car, Suzana; Socha, Amanda L; Hindt, Maria N; Punshon, Tracy; Guerinot, Mary Lou

    2017-09-08

    Understanding how seeds obtain and store nutrients is key to developing crops with higher agronomic and nutritional value. We have uncovered unique patterns of micronutrient localization in seeds using synchrotron X-ray fluorescence (SXRF). Although all four members of the Arabidopsis thaliana Mn-CDF family can transport Mn, here we show that only mtp8-2 has an altered Mn distribution pattern in seeds. In an mtp8-2 mutant, Mn no longer accumulates in hypocotyl cortex cells and sub-epidermal cells of the embryonic cotyledons, but rather accumulates with Fe in the cells surrounding the vasculature, a pattern previously shown to be determined by the vacuolar transporter VIT1. We also show that MTP8, unlike the other three Mn-CDF family members, can transport Fe and is responsible for localization of Fe to the same cells that store Mn. When both the VIT1 and MTP8 transporters are non-functional, there is no accumulation of Fe or Mn in specific cell types; rather these elements are distributed amongst all cell types in the seed. Disruption of the putative Fe binding sites in MTP8 resulted in loss of ability to transport Fe but did not affect the ability to transport Mn.

  20. DETERMINATION OF PERMEATION PROPERTIES OF GAS THROUGH POLYMER MEMBRANE BY GAS CHROMATOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    JIN Xigao; FU Xiucheng; ZHAN Yongjian; QIAN Renyuan

    1987-01-01

    An apparatus constructed for measuring permeation properties of polymer membranes using a mixture of gases is described. A gas chromatographic system was applied to determine the individual transport characteristics of component gases without a vacuum line. This paper also discusses some experimental factors effecting the precision of measurement. The results show that there is a linear relationship between the permeation time and the volume of the gas permeated through the membrane within certain permeation period, which depends on the permeation rate (from 10-4 to 10-7 cm3 (STP)/cm2.sec. cmHg) of the membrane. The reproducibility has been found to be good with a relative standard deviation of 3.5%. This method is more sensitive, considerably faster and more convenient for determining both the permeability coefficient and the separation factor of a polymer membrane from a chromat ogram using mixed penetrant gases.

  1. Biphasic flow: structure and upscaling, consequences on macroscopic transport properties

    CERN Document Server

    Toussaint, Renaud; Méheust, Yves; Løvoll, Grunde; Jankov, Mihailo; Schäfer, Gerhard; Schmittbuhl, Jean

    2012-01-01

    In disordered porous media, two-phase flow of immiscible fluids (biphasic flow) is organized in patterns that sometimes exhibit fractal geometries over a range of length scales, depending on the capillary, gravitational and viscous forces at play. These forces, as well as the boundary conditions, also determine whether the flow leads to the appearance of fingering pathways, i.e., unstable flow, or not. We present here a short review of these aspects, focusing on drainage and summarizing when these flows are expected to be stable or not, what fractal dimensions can be expected, and in which range of scales. We base our review on experimental studies performed in two-dimensional Hele-Shaw cells, or addressing three dimensional porous media by use of several imaging techniques. We first present configurations in which solely capillary forces and gravity play a role. Next, we review configurations in which capillarity and viscosity are the main forces at play. Eventually, we examine how the microscopic geometry o...

  2. Charge distribution and transport properties in reduced ceria phases: A review

    Science.gov (United States)

    Shoko, E.; Smith, M. F.; McKenzie, Ross H.

    2011-12-01

    The question of the charge distribution in reduced ceria phases (CeO2-x) is important for understanding the microscopic physics of oxygen storage capacity, and the electronic and ionic conductivities in these materials. All these are key properties in the application of these materials in catalysis and electrochemical devices. Several approaches have been applied to study this problem, including ab initio methods. Recently [1], we applied the bond valence model (BVM) to discuss the charge distribution in several different crystallographic phases of reduced ceria. Here, we compare the BVM results to those from atomistic simulations to determine if there is consistency in the predictions of the two approaches. Our analysis shows that the two methods give a consistent picture of the charge distribution around oxygen vacancies in bulk reduced ceria phases. We then review the transport theory applicable to reduced ceria phases, providing useful relationships which enable comparison of experimental results obtained by different techniques. In particular, we compare transport parameters obtained from the observed optical absorption spectrum, α(ω), dc electrical conductivity with those predicted by small polaron theory and the Harrison method. The small polaron energy is comparable to that estimated from α(ω). However, we found a discrepancy between the value of the electron hopping matrix element, t, estimated from the Marcus-Hush formula and that obtained by the Harrison method. Part of this discrepancy could be attributed to the system lying in the crossover region between adiabatic and nonadiabatic whereas our calculations assumed the system to be nonadiabatic. Finally, by considering the relationship between the charge distribution and electronic conductivity, we suggest the possibility of low temperature metallic conductivity for intermediate phases, i.e., x˜0.3. This has not yet been experimentally observed.

  3. High temperature transport properties of BaZn{sub 2}Sn{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Aydemir, U., E-mail: uaydemir@caltech.edu [Department of Materials Science, California Institute of Technology, 1200 E California Blvd., Pasadena (United States); Department of Chemistry, Koç University, Rumelifeneri Yolu, Sariyer, Istanbul (Turkey); Zevalkink, A.; Bux, S. [Thermal Energy Conversion Technologies Group, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena (United States); Snyder, G.J. [Department of Materials Science, California Institute of Technology, 1200 E California Blvd., Pasadena (United States)

    2015-02-15

    Highlights: • BaZn{sub 2}Sn{sub 2} is obtained from the solid state reaction and Sn flux methods. • BaZn{sub 2}Sn{sub 2} structure contains PbO-like {ZnSn_4_/_4} and anti-PbO-like {SnZn_4_/_4} layers. • Weak or nonbonding interaction in BaZn{sub 2}Sn{sub 2} may lead to partially filled orbitals. • BaZn{sub 2}Sn{sub 2} displays a metal-like electronic and thermal transport properties. - Abstract: BaZn{sub 2}Sn{sub 2} (space group P4/nmm, a = 4.7459(5) Å, c = 11.330(2) Å, Z = 2) crystallizes in the CaBe{sub 2}Ge{sub 2} structure type with a polyanionic framework comprising alternately stacked PbO-like {ZnSn_4_/_4} and anti-PbO-like {SnZn_4_/_4} layers along the c-axis. BaZn{sub 2}Sn{sub 2} samples were obtained by either direct solid state reaction of the elements or from a Sn-flux method in very high yield with very small amount of β-Sn as the secondary phase. The samples were characterized by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The chemical compositions were determined to be off-stoichiometric with Zn/Sn ratio lower than 1.0 and Sn2 atoms in the crystal structure were found to be either loosely bonded or not bonded which might lead to an incomplete charge balance. Electrical and thermal transport measurements have been performed in the temperature range 300-773 K. BaZn{sub 2}Sn{sub 2} displays the electrical resistivity of a metal (or semimetal) along with very low Seebeck coefficients and relatively high thermal conductivity.

  4. Seismic properties of volcanic rocks from Montagne Pelée (Martinique, Lesser Antilles) and their relations to transport properties

    Science.gov (United States)

    Bernard, M.-L.; Zamora, M.

    2012-04-01

    Numerous laboratory and theoretical studies on the physical properties of rocks and their relationships - lead mainly in the framework of petroleum exploration - show that rock physics is necessary for an accurate quantitative interpretation of geophysical observations. Moreover joint inversion of different geophysical datasets is emerging as an important tool to enhance resolution and decrease inversion artifacts in imaging of structurally complex areas such as volcanoes. In many cases, the coupling between the inverted parameters is based on empirical or theoretical relationships derived from laboratory data. Consequently rock physics can be used to: interpret simultaneously several geophysical datasets on volcanoes when they are available, improve the imaging of volcano structures, and better understand the coupled processes that can occur during volcanic unrest. It's in this context that we lead a laboratory study on the transport properties (permeability, thermal and electrical conductivities) and seismic properties (velocity and attenuation of P and S waves) of volcanic rocks representative of Montagne Pelée (Martinique) deposits. In this presentation we will focus on (1) the seismic properties and (2) the relations between seismic and transport properties. The 43 samples collected are representative of the main lithological units of this volcano: vesicular lava blocks and indurated ashed from indurated block-and-ash flows also called breccias, vesicular lava blocks from "Pelean nuee ardente" flows, scoriae from scoria flows, pumices from ash-and-pumices flows, and dense lava blocks from lava flows and lava domes. Their total porosity varies over a wide range from 4 to 73%. Since the samples present similar chemical and mineralogical compositions (andesites), the main difference between the samples comes from their pore structure and reflects differences in the mechanisms of magma degassing and vesiculation during their formation (Bernard et al., 2007). This

  5. METHODOLOGY FOR DETERMINATION OF ECONOMIC LOSSES AT COORDINATED REGULATION OF TRANSPORT-PEDESTRIAN FLOWS

    Directory of Open Access Journals (Sweden)

    D. V. Kapsky

    2010-01-01

    Full Text Available The paper presents some peculiar features of the developed methodology for determination of economic losses at coordinated regulation of transport and pedestrian flow movement. Preconditions for introduction of pre-signals on light objects which raise efficiency of coordinated control over transport flows are considered separately in the paper. The paper proposes to estimate the coordinated regulation by such criterion as minimization of economic, ecological and emergency losses. Basic principles on investigation of main costs in the process of  coordinated pack movement are cited in the paper.

  6. Aerosol properties and radiative forcing for three air masses transported in Summer 2011 to Sopot, Poland

    Science.gov (United States)

    Rozwadowska, Anna; Stachlewska, Iwona S.; Makuch, P.; Markowicz, K. M.; Petelski, T.; Strzałkowska, A.; Zieliński, T.

    2013-05-01

    Properties of atmospheric aerosols and solar radiation reaching the Earth's surface were measured during Summer 2011 in Sopot, Poland. Three cloudless days, characterized by different directions of incoming air-flows, which are typical transport pathways to Sopot, were used to estimate a radiative forcing due to aerosols present in each air mass.

  7. A whole range hygric material model: Modelling liquid and vapour transport properties in porous media

    DEFF Research Database (Denmark)

    Scheffler, Gregor Albrecht; Plagge, Rudolf

    2010-01-01

    This paper addresses the modelling of hygric material coefficients bridging the gap between measured material properties and the non-linear storage and transport coefficients in the transfer equation. The conductivity approach and a bundle of tubes model are the basis. By extending this model...

  8. Predicting Soil-Air and Soil-Water Transport Properties During Soil Vapor Extraction

    DEFF Research Database (Denmark)

    Poulsen, Tjalfe

    designing and operating remediation systems. Simple and accurate models for estimating soil properties from soil parameters that are easy to measure are useful in connection with preliminary remedial investigations and evaluation of remedial technologies. In this work simple models for predicting transport...

  9. A law of mixtures for transport properties in binary particulate composites

    Science.gov (United States)

    Duncan, K. L.; Lodenquai, J. F.; Wagh, A. S.; Goretta, K. C.

    1998-09-01

    A connected-grain model was developed earlier to explain mechanical and thermal properties of porous ceramics and sedimentary rocks. We have now generalized this model for binary particulate composites, based on simulation of a connected-grain structure of individual components of the composites by randomly selecting individual grains and shrinking them. Repetition of this procedure results in a structure of a binary particulate composite that contains channels of individual components, through which transport occurs. We developed a generalized law of mixtures in which transport properties are expressed as scaling relationships that depend on the shrinking parameter expressed as an exponent. This parameter provides the skewness of the distribution of the grains. The model is compared with various transport properties of binary composites reported in the literature. In addition, the model is tested on YBa2Cu3Ox superconductors and Ag composites that were fabricated in our laboratory and tested for electrical conductivity and elastic modulus. This test demonstrates how the model predicts two entirely different transport properties through their common microstructure and grain-size distribution.

  10. Quark Transport Properties in the Region of Coexistence of Both Hadronic and QGP Phases

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiang-Jun; LI Hong; WANG Gang; ZHANG Wei-Ning; HUO Lei

    2001-01-01

    The physical picture of coexistence of both hadronic and QGP phases is given by Friedberg and T.D. Lee's nontopology soliton model. The transport properties of quark in color space and spin space in a system of two-phase coexistence are investigated from both quantum and classical theories.

  11. Ab initio description of the thermoelectric properties of heterostructures in the diffusive limit of transport

    DEFF Research Database (Denmark)

    Hinsche, Nicki Frank; Rittweger, Florian; Hölzer, Martin

    2016-01-01

    -principles calculations a consistent and convenient method is presented to fully describe the thermoelectric properties in the diffusive limit of transport for bulk systems and their associated heterostructures. While fundamentals of the functionality of phonon-blocking and electron-transmitting superlattices could...

  12. Electrical transport properties of oligothiophene based molecular films studied by current sensing Atomic Force Microscopy

    NARCIS (Netherlands)

    Hendriksen, Bas L.M.; Martin, Florent; Qi, Yabing; Qi, Y.; Mauldin, Clayton; Vukmirovic, Nenad; Ren, JunFeng; Wormeester, Herbert; Katan, Allard J.; Altoe, Virginia; Aloni, Shaul; Frechet, Jean M.J.; Wang, Lin-Wang; Salmeron, Miquel

    2011-01-01

    Using conducting probe atomic force microscopy (CAFM) we have investigated the electrical conduction properties of monolayer films of a pentathiophene derivative on a SiO2/Si-p+ substrate. By a combination of current–voltage spectroscopy and current imaging we show that lateral charge transport

  13. Quantum transport properties of the three-dimensional Dirac semimetal Cd3As2 single crystals

    Science.gov (United States)

    He, Lan-Po; Li, Shi-Yan

    2016-11-01

    The discovery of the three-dimensional Dirac semimetals have expanded the family of topological materials, and attracted massive attentions in recent few years. In this short review, we briefly overview the quantum transport properties of a well-studied three-dimensional Dirac semimetal, Cd3As2. These unusual transport phenomena include the unexpected ultra-high charge mobility, large linear magnetoresistivity, remarkable Shubnikov-de Hass oscillations, and the evolution of the nontrivial Berry’s phase. These quantum transport properties not only reflect the novel electronic structure of Dirac semimetals, but also give the possibilities for their future device applications. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB821402 and 2015CB921401), the National Natural Science Foundation of China, the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, and STCSM of China (Grant No. 15XD1500200).

  14. Theoretical study on charge injection and transport properties of six emitters with push-pull structure

    Science.gov (United States)

    Lin, Tao; Liu, Xiaojun; Lou, Zhidong; Hou, Yanbing; Teng, Feng

    2014-08-01

    The charge injection and transport properties of six organic light-emitting molecules with push-pull structures were studied by theoretical calculations. The ground-state geometries for the neutral, cationic and anionic states were optimized using density functional theory. Subsequently, the ionization potentials and electron affinities were calculated. We computed the reorganization energies and the transfer integrals based on the Marcus electron transfer theory. It was found that in addition to being emitters the six compounds are multifunctional materials being capable of transport for both holes and electrons. Moreover, the double-branched compound DCDPC2 was found to have higher charge injection ability and better balanced charge transport properties than single-branched compounds.

  15. Transport properties of zigzag graphene nanoribbons adsorbed with single iron atom

    Institute of Scientific and Technical Information of China (English)

    杨玉娥; 肖杨; 颜晓红; 戴昌杰

    2015-01-01

    We have performed density-functional calculations of the transport properties of the zigzag graphene nanoribbon (ZGNR) adsorbed with a single iron atom. Two adsorption configurations are considered, i.e., iron adsorbed on the edge and on the interior of the nanoribbon. The results show that the transport features of the two configurations are similar. However, the transport properties are modified due to the scattering effects induced by coupling of the ZGNR band states to the localized 3d-orbital state of the iron atom. More importantly, one can find that several dips appear in the transmission curve, which is closely related to the above mentioned coupling. We expect that our results will have potential applications in graphene-based spintronic devices.

  16. Further developments in material properties determined by vibration analysis

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang; Andreasen, Lotte; Seifert, Mette

    1997-01-01

    have been studied by testing a number of building materials. The method has been PC-integrated with the Brüel & Kjær's type 3550 vibration equipment - and special user menus have been developed to facilitate handling of the method in practice. Limits on range of test frequencies applied are discussed...... with respect to configurations of vibration equipment and shapes of test specimens used. Sensitivity studies have been made to identify sources of errors which may disturb the reliability of the method used in practice. Practical aspects with respect to test set-ups are considered in these studies - as well......A method was described in Materialnyt 1 (1995) on "Material properties determined by vibration analysis". This new method of materials testing has been further developed as the result of research at the Building Materials Laboratory, Technical University of Denmark.Practical aspects of the method...

  17. Novel evaporation experiment to determine soil hydraulic properties

    Directory of Open Access Journals (Sweden)

    K. Schneider

    2006-01-01

    Full Text Available A novel experimental approach to determine soil hydraulic material properties for the dry and very dry range is presented. Evaporation from the surface of a soil column is controlled by a constant flux of preconditioned air and the resulting vapour flux is measured by infrared absorption spectroscopy. The data are inverted under the assumptions that (i the simultaneous movement of water in the liquid and vapour is represented by Richards' equation with an effective hydraulic conductivity and that (ii the coupling between the soil and the well-mixed atmosphere can be modelled by a boundary layer with a constant transfer resistance. The optimised model fits the data exceptionally well. Remaining deviations during the initial phase of an experiment are thought to be well-understood and are attributed to the onset of the heat flow through the column which compensates the latent heat of evaporation.

  18. [Solanine and chaconine: occurrence, properties, methods for determination].

    Science.gov (United States)

    Badowski, P; Urbanek-Karłowska, B

    1999-01-01

    Glycoalkaloids are naturally occurring toxicants in plants that are members of the Solanaceae family. In this paper occurrence of glycoalkaloids, especially solanine and chaconine in potatoes and tomatoes, were reviewed. Basing on literature, toxicological properties and methods of determination were reported. Attention was paid to common content of glycoalkaloids in potatoes and tomatoes and their commercial products. Solanine and chaconine are usually present at low levels in large majority of current commercial varieties but they can accumulate to high levels in greened, stored, damaged potatoes. High concentration may cause acute poisoning, including gastro-intestinal and neurological disturbances, in man. The upper limit, recognized as a safe (non-toxic), was presented. According to WHO normal levels in potatoes 20-100 mg per kg of potatoes is not of toxicological concern.

  19. Determination of Dark Matter Properties at High-Energy Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Baltz, Edward A.; Battaglia, Marco; Peskin, Michael E.; Wizansky, Tommer

    2006-11-05

    If the cosmic dark matter consists of weakly-interacting massive particles, these particles should be produced in reactions at the nextgeneration of high-energy accelerators. Measurements at these accelerators can then be used to determine the microscopic properties of the dark matter. From this, we can predict the cosmic density, the annihilation cross sections, and the cross sections relevant to direct detection. In this paper, we present studies in supersymmetry models with neutralino dark matter that give quantitative estimates of the accuracy that can be expected. We show that these are well matched to the requirements of anticipated astrophysical observations of dark matter. The capabilities of the proposed International Linear Collider (ILC) are expected to play a particularly important role in this study.

  20. Determination of Dark Matter Properties at High-Energy Collider

    Energy Technology Data Exchange (ETDEWEB)

    Baltz, Edward A.; Battaglia, Marco; Peskin, Michael E.; Wizansky, Tommer

    2006-02-24

    If the cosmic dark matter consists of weakly-interacting massive particles, these particles should be produced in reactions at the next generation of high-energy accelerators. Measurements at these accelerators can then be used to determine the microscopic properties of the dark matter. From this, we can predict the cosmic density, the annihilation cross sections, and the cross sections relevant to direct detection. In this paper, we present studies in supersymmetry models with neutralino dark matter that give quantitative estimates of the accuracy that can be expected. We show that these are well matched to the requirements of anticipated astrophysical observations of dark matter. The capabilities of the proposed International Linear Collider (ILC) are expected to play a particularly important role in this study.

  1. Determination of Hillside Hydraulic Properties With an Hillslope Infiltrometer

    Science.gov (United States)

    Steenhuis, T. S.; Mendoza, G.; Hanson, D.; Walter, M. T.

    2001-12-01

    Watersheds, in many parts of the world, consist of sloping soils with a dense subsoil at shallow depth. Very few measurement techniques exist for realistically determining hydraulic properties in situ on these hillside soils. A hillslope infiltrometer, open at the bottom, top, and downhill sides, was developed that could measure the vertical and lateral hydraulic conductivity by applying increasing amounts of rainfall. The infiltrometer was tested on the steeply sloping hillsides of Honduras and proved useful in the characterization of subsurface flow under five different land uses. The findings were in agreement with the farmers' perception: The hillsides with the infiltration rates higher than the prevailing rainfall rates were not considered by the farmers in need of conservation practices.

  2. Determination of Properties of Selected Fresh and Processed Medicinal Plants

    Directory of Open Access Journals (Sweden)

    Shirley G. Cabrera

    2015-11-01

    Full Text Available The study aimed to determine the chemical properties, bioactive compounds, antioxidant activity and toxicity level of fresh and processed medicinal plants such as corn (Zea mays silk, pancitpancitan (Peperomiapellucida leaves, pandan (Pandanus amaryllifolius leaves, and commercially available tea. The toxicity level of the samples was measured using the Brine Shrimp Lethality Assay (BSLA. Statistical analysis was done using Statistical Package for Social Sciences (SPSS. Results showed that in terms of chemical properties there is significant difference between fresh and processed corn silk except in crude fiber content was noted. Based on proximate analyses of fresh and processed medicinal plants specifically in terms of % moisture, %crude protein and % total carbohydrates were also observed. In addition, there is also significant difference on bioactive compound contents such as total flavonoids and total phenolics between fresh and processed corn silk except in total vitamin E (TVE content. Pandan and pancit-pancitan showed significant difference in all bioactive compounds except in total antioxidant content (TAC. Fresh pancit-pancitan has the highest total phenolics content (TPC and TAC, while the fresh and processed corn silk has the lowest TAC and TVE content, respectively. Furthermore, results of BSLA for the three medicinal plants and commercially available tea extract showed after 24 hours exposure significant difference in toxicity level was observed. The percentage mortality increased with an increase in exposure time of the three medicinal plants and tea extract. The results of the study can served as baseline data for further processing and commercialization of these medicinal plants.

  3. Determination of replicate composite bone material properties using modal analysis.

    Science.gov (United States)

    Leuridan, Steven; Goossens, Quentin; Pastrav, Leonard; Roosen, Jorg; Mulier, Michiel; Denis, Kathleen; Desmet, Wim; Sloten, Jos Vander

    2017-02-01

    Replicate composite bones are used extensively for in vitro testing of new orthopedic devices. Contrary to tests with cadaveric bone material, which inherently exhibits large variability, they offer a standardized alternative with limited variability. Accurate knowledge of the composite's material properties is important when interpreting in vitro test results and when using them in FE models of biomechanical constructs. The cortical bone analogue material properties of three different fourth-generation composite bone models were determined by updating FE bone models using experimental and numerical modal analyses results. The influence of the cortical bone analogue material model (isotropic or transversely isotropic) and the inter- and intra-specimen variability were assessed. Isotropic cortical bone analogue material models failed to represent the experimental behavior in a satisfactory way even after updating the elastic material constants. When transversely isotropic material models were used, the updating procedure resulted in a reduction of the longitudinal Young's modulus from 16.00GPa before updating to an average of 13.96 GPa after updating. The shear modulus was increased from 3.30GPa to an average value of 3.92GPa. The transverse Young's modulus was lowered from an initial value of 10.00GPa to 9.89GPa. Low inter- and intra-specimen variability was found. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Neighborhood properties are important determinants of temperature sensitive mutations.

    Directory of Open Access Journals (Sweden)

    Svetlana Lockwood

    Full Text Available Temperature-sensitive (TS mutants are powerful tools to study gene function in vivo. These mutants exhibit wild-type activity at permissive temperatures and reduced activity at restrictive temperatures. Although random mutagenesis can be used to generate TS mutants, the procedure is laborious and unfeasible in multicellular organisms. Further, the underlying molecular mechanisms of the TS phenotype are poorly understood. To elucidate TS mechanisms, we used a machine learning method-logistic regression-to investigate a large number of sequence and structure features. We developed and tested 133 features, describing properties of either the mutation site or the mutation site neighborhood. We defined three types of neighborhood using sequence distance, Euclidean distance, and topological distance. We discovered that neighborhood features outperformed mutation site features in predicting TS mutations. The most predictive features suggest that TS mutations tend to occur at buried and rigid residues, and are located at conserved protein domains. The environment of a buried residue often determines the overall structural stability of a protein, thus may lead to reversible activity change upon temperature switch. We developed TS prediction models based on logistic regression and the Lasso regularized procedure. Through a ten-fold cross-validation, we obtained the area under the curve of 0.91 for the model using both sequence and structure features. Testing on independent datasets suggested that the model predicted TS mutations with a 50% precision. In summary, our study elucidated the molecular basis of TS mutants and suggested the importance of neighborhood properties in determining TS mutations. We further developed models to predict TS mutations derived from single amino acid substitutions. In this way, TS mutants can be efficiently obtained through experimentally introducing the predicted mutations.

  5. Electronic structure and quantum transport properties of metallic and semiconducting nanowires

    Science.gov (United States)

    Simbeck, Adam J.

    The future of the semiconductor industry hinges upon new developments to combat the scaling issues that currently afflict two main chip components: transistors and interconnects. For transistors this means investigating suitable materials to replace silicon for both the insulating gate and the semiconducting channel in order to maintain device performance with decreasing size. For interconnects this equates to overcoming the challenges associated with copper when the wire dimensions approach the confinement limit, as well as continuing to develop low-k dielectric materials that can assure minimal cross-talk between lines. In addition, such challenges make it increasingly clear that device design must move from a top-down to a bottom-up approach in which the desired electronic characteristics are tailored from first-principles. It is with such fundamental hurdles in mind that ab initio calculations on the electronic and quantum transport properties of nanoscale metallic and semiconducting wires have been performed. More specifically, this study seeks to elaborate on the role played by confinement, contacts, dielectric environment, edge decoration, and defects in altering the electronic and transport characteristics of such systems. As experiments continue to achieve better control over the synthesis and design of nanowires, these results are expected to become increasingly more important for not only the interpretation of electronic and transport trends, but also in engineering the electronic structure of nanowires for the needs of the devices of the future. For the metallic atomic wires, the quantum transport properties are first investigated by considering finite, single-atom chains of aluminum, copper, gold, and silver sandwiched between gold contacts. Non-equilibrium Green's function based transport calculations reveal that even in the presence of the contact the conductivity of atomic-scale aluminum is greater than that of the other metals considered. This is

  6. State-specific transport properties of partially ionized flows of electronically excited atomic gases

    Science.gov (United States)

    Istomin, V. A.; Kustova, E. V.

    2017-03-01

    State-to-state approach for theoretical study of transport properties in atomic gases with excited electronic degrees of freedom of both neutral and ionized species is developed. The dependence of atomic radius on the electronic configuration of excited atoms is taken into account in the transport algorithm. Different cutoff criteria for increasing atomic radius are discussed and the limits of applicability for these criteria are evaluated. The validity of a Slater-like model for the calculation of state-resolved transport coefficients in neutral and ionized atomic gases is shown. For ionized flows, a method of evaluation for effective cross-sections of resonant charge-transfer collisions is suggested. Accurate kinetic theory algorithms for modelling the state-specific transport properties are applied for the prediction of transport coefficients in shock heated flows. Based on the numerical observations, different distributions over electronic states behind the shock front are considered. For the Boltzmann-like distributions at temperatures greater than 14,000 K, an important effect of electronic excitation on the partial thermal conductivity and viscosity coefficients is found for both neutral and ionized atomic gases: increasing radius of excited atoms causes a strong decrease in these transport coefficients. Similarly, the presence of electronically excited states with increased atomic radii leads to reduced diffusion coefficients. Nevertheless the overall impact of increasing effective cross-sections on the transport properties just behind the shock front under hypersonic reentry conditions is found to be minor since the populations of high-lying electronic energy levels behind the shock waves are low.

  7. FY:15 Transport Properties of Run-of-Mine Salt Backfill ? Unconsolidated to Consolidated.

    Energy Technology Data Exchange (ETDEWEB)

    Dewers, Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Heath, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Leigh, Christi D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-28

    The nature of geologic disposal of nuclear waste in salt formations requires validated and verified two-phase flow models of transport of brine and gas through intact, damaged, and consolidating crushed salt. Such models exist in other realms of subsurface engineering for other lithologic classes (oil and gas, carbon sequestration etc. for clastics and carbonates) but have never been experimentally validated and parameterized for salt repository scenarios or performance assessment. Models for waste release scenarios in salt back-fill require phenomenological expressions for capillary pressure and relative permeability that are expected to change with degree of consolidation, and require experimental measurement to parameterize and validate. This report describes a preliminary assessment of the influence of consolidation (i.e. volume strain or porosity) on capillary entry pressure in two phase systems using mercury injection capillary pressure (MICP). This is to both determine the potential usefulness of the mercury intrusion porosimetry method, but also to enable a better experimental design for these tests. Salt consolidation experiments are performed using novel titanium oedometers, or uniaxial compression cells often used in soil mechanics, using sieved run-of-mine salt from the Waste Isolation Pilot Plant (WIPP) as starting material. Twelve tests are performed with various starting amounts of brine pore saturation, with axial stresses up to 6.2 MPa (~900 psi) and temperatures to 90°C. This corresponds to UFD Work Package 15SN08180211 milestone “FY:15 Transport Properties of Run-of-Mine Salt Backfill – Unconsolidated to Consolidated”. Samples exposed to uniaxial compression undergo time-dependent consolidation, or creep, to various degrees. Creep volume strain-time relations obey simple log-time behavior through the range of porosities (~50 to 2% as measured); creep strain rate increases with temperature and applied stress as expected. Mercury porosimetry

  8. Wireless Location Determination for Mobile Objects Based on GSM in Intelligent Transportation Systems

    Institute of Scientific and Technical Information of China (English)

    徐志扬; 施鹏飞

    2003-01-01

    The mobile object (MO) location determination technologies which can be used in intelligent transportation system (ITS) are studied in this paper. The principles and characteristics of wireless location determination technologies are introduced and the characteristics of GSM useful for location determination are also summarized. An experimental positioning system based on GSM is proposed, and the architecture is described. TOA method based on GSM signals and TDOA method are used in the experimental system. Moreover, the methods are simulated. The performance of the positioning methods is assessed in the simulation environment, and the accuracy for 67% mobile stations (MS) is 70m in urban areas.

  9. Transport properties of room temperature ionic liquids from classical molecular dynamics

    CERN Document Server

    Andreussi, Oliviero

    2012-01-01

    Room Temperature Ionic Liquids (RTILs) have attracted much of the attention of the scientific community in the past decade due the their novel and highly customizable properties. Nonetheless their high viscosities pose serious limitations to the use of RTILs in practical applications. To elucidate some of the physical aspects behind transport properties of RTILs, extensive classical molecular dynamics (MD) calculations are reported. Bulk viscosities and ionic conductivities of butyl-methyl-imidazole based RTILs are presented over a wide range of temperatures. The dependence of the properties of the liquids on simulation parameters, e.g. system size effects and choice of the interaction potential, is analyzed.

  10. Electronic transport properties of fullerene functionalized carbon nanotubes: Ab initio and tight-binding calculations

    DEFF Research Database (Denmark)

    Fürst, Joachim Alexander; Hashemi, J.; Markussen, Troels

    2009-01-01

    techniques and tight-binding calculations to illustrate these materials' transmission properties and give physical arguments to interpret the numerical results. Specifically, above the Fermi energy we find a strong reduction in electron transmission due to localized states in certain regions of the structure......Fullerene functionalized carbon nanotubes-NanoBuds-form a novel class of hybrid carbon materials, which possesses many advantageous properties as compared to the pristine components. Here, we report a theoretical study of the electronic transport properties of these compounds. We use both ab initio...

  11. Tribological properties of epoxy composite materials for marine and river transport

    Science.gov (United States)

    Buketov, A. V.; Maruschak, P. O.; Brailo, N. V.; Akimov, A. V.; Kobelnik, O. S.; Panin, S. V.

    2016-11-01

    Tribological properties of epoxy composites filled with thermoplastics and dispersed particles under sea water environment were analyzed. It has been revealed that the composition, sliding friction conditions, as well as the marine environment, substantially affect the tribological properties of the materials. The improvement of tribological properties of epoxycomposite thermosetting plastics after their filling with thermoplastic polyamide PA-6 granules under friction in sea water environment has been proved. The recommendations on applying the developed material in friction parts for marine and river transport were formulated.

  12. Surface and transport properties of Cu-Sn-Ti liquid alloys

    Institute of Scientific and Technical Information of China (English)

    R. Novakovic; E. Ricci; S. Amore; T. Lanata

    2006-01-01

    The lack of experimental data and / or limited experimental information concerning both surface and transport properties of liquid alloys often require the prediction of these quantities. An attempt has been made to link the thermophysical properties of a ternary Cu-Sn-Ti system and its binary Cu-Sn, Cu-Ti and Sn-Ti subsystems with the bulk through the study of the concentration dependence of various thermodynamic, structural, surface and dynamic properties in the frame of the statistical mechanical theory in conjunction with the quasi-lattce theory (QLT). This formalism provides valuable qualitative insight into mixing processes that occur in molten alloys.

  13. Applications of asymmetric nanotextured parylene surface using its wetting and transport properties

    Science.gov (United States)

    Sekeroglu, Koray

    In this thesis, basic digital fluidics devices were introduced using polymeric nanorods (nano-PPX) inspired from nature. Natural inspiration ignited this research by observing butterfly wings, water strider legs, rye grass leaves, and their asymmetric functions. Nano-PPX rods, manufactured by an oblique angle polymerization (OAP) method, are asymmetrically aligned structures that have unidirectional wetting properties. Nano-PPX demonstrates similar functions to the directional textured surfaces of animals and plants in terms of wetting, adhesion, and transport. The water pin-release mechanism on the asymmetric nano-PPX surface with adhesion function provides a great transport property. How the asymmetry causes transport is discussed in terms of hysteresis and interface contact of water droplets. In this study, the transport property of nano-PPX rods is used to guide droplets as well as transporting cargo such as microgels. With the addition of tracks on the nano-PPX rods, the surfaces were transformed into basic digital fluidics devices. The track-assisted nano-PPX has been employed to applications (i.e. sorting, mixing, and carrying cargo particles). Thus, digital fluidics devices fabricated on nano-PPX surface is a promising pathway to assemble microgels in the field of bioengineering. The characterization of the nano textured surface was completed using methods such as Scanning Electron Microscopy, Atomic Force Microscopy, Contact Angle Goniometry, and Fourier Transform Infra-Red Spectroscopy. These methods helped to understand the physical and chemical properties of nano-PPX. Parameters such as advancing and receding contact angles, nanorod tilt angle, and critical drop volumes were utilized to investigate the anisotropic wetting properties of nano-PPX surface. This investigation explained the directional wetting behavior of the surface as well as approaching new design parameters for adjusting surface properties. The nanorod tilt angle was a key parameter

  14. Determination of Physical Properties of Some Agricultural Grains

    Directory of Open Access Journals (Sweden)

    S. Gürsoy

    2010-08-01

    Full Text Available In this study, for the purpose of determining physical and aerodynamic properties, some varieties of wheat, barley, chickpea and lentil were used. The length, width, thickness, geometric mean diameter, equivalent sphere diam eter, sphericity, seed mass, bulk density, true density, projected area, terminal velocity, drag coefficient of each grain variety were determined. The theoretical terminal velocities of those grains were calculated by using equations corrected with the shape factor. For all the grains, theoretical terminal velocities were lower than the experimental values. The average experimental terminal velocity was found to be in the range of 7.52 to 8.14 m/s for wheat varieties, 7.04 to 7.07 m /s for barley varieties, 7.72 to 7.78 m/s for lentil varieties and 11.15 to 12.01 m/s for chickpea varieties. The drag coefficients of seeds according to projected areas in different positions and equivalent spheres were calculated. The drag coefficient in the position of the lowest projected area for all the grain varieties was higher than that in the other position.

  15. Transport and mechanical properties of self consolidating concrete with high volume fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Mustafa Sahmaran; Ismail O. Yaman; Mustafa Tokyay [Gaziantep University, Gaziantep (Turkey). Department of Civil Engineering

    2009-02-15

    This paper presents the transport and mechanical properties of self consolidating concrete that contain high percentages of low-lime and high-lime fly ash (FA). Self consolidating concretes (SCC) containing five different contents of high-lime FA and low-lime FA as a replacement of cement (30, 40, 50, 60 and 70 by weight of total cementitious material) are examined. For comparison, a control SCC mixture without any FA was also produced. The fresh properties of the SCCs were observed through, slump flow time and diameter, V-funnel flow time, L-box height ratio, and segregation ratio. The hardened properties included the compressive strength, split tensile strength, drying shrinkage and transport properties (absorption, sorptivity and rapid chloride permeability tests) up to 365 days. Test results confirm that it is possible to produce SCC with a 70% of cement replacement by both types of FA. The use of high volumes of FA in SCC not only improved the workability and transport properties but also made it possible to produce concretes between 33 and 40 MPa compressive strength at 28 days, which exceeds the nominal compressive strength for normal concrete (30 MPa).

  16. The electronic transport properties of graphene-like beryllium sulfide nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    An, Yipeng, E-mail: ypan@htu.edu.cn; Wang, Tianxing; Fu, Zhaoming; Chu, Xingli; Xu, Guoliang

    2015-09-11

    The electronic transport properties of zigzag beryllium sulfide nanoribbons (ZBeSNRs) are investigated by first-principles calculations. The results indicate that the electrons flow mainly through the two edges of ZBeSNRs. The electron transmission pathways are analyzed in detail. The ZBeSNRs show the remarkable negative differential resistance (NDR) properties, which are independent of the nanoribbon width due to their very similar band structures. The NDR behavior can be maintained by introducing a Be or S atom vacancy defect. The H-passivated ZBeSNR presents the interesting current-limited effect. The ZBeSNRs could be the promising candidates for the future nano devices, such as NDR devices. - Highlights: • The electronic transport properties of zigzag BeS nanoribbons (ZBeSNRs) are investigated. • The ZBeSNRs show the remarkable negative differential resistance (NDR) properties. • The electronic transport properties of ZBeSNRs are independent of the nanoribbon width. • The NDR behavior can be maintained by introducing a Be or S atom vacancy defect. • The H-passivated ZBeSNR presents the interesting current-limited effect.

  17. Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Govind Mallick

    2017-08-01

    Full Text Available Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs from hydrothermally grown Ni(OH2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (∼0.7 V electron tunneling than the parent Ni(OH2.

  18. Transport properties and electroanalytical response characteristics of drotaverine ion-selective sensors.

    Science.gov (United States)

    Kharitonov, Sergey V

    2005-08-01

    The construction and electroanalytical response characteristics of poly(vinyl chloride) matrix ion-selective sensors (ISSs) for drotaverine hydrochloride are described. The membranes incorporate ion-association complexes of drotaverine with tetraphenylborate, picrate, tetraiodomercurate, tetraiodobismuthate, Reinecke salt, and heteropolycompounds of Keggin structure-molybdophosphoric acid, tungstophosphoric acid, molybdosiliconic acid and tungstosiliconic acid as electroactive materials for ionometric sensor controls. These ISSs have a linear response to drotaverine hydrochloride over the range 8 x 10(-6) to 5 x 10(-2) mol L(-1) with cationic slopes from 51 to 58 mV per concentration decade. These ISSs have a fast response time (up to 1 min), a low determination limit (down to 4.3 x 10(-6) mol L(-1)), good stability (3-5 weeks), and reasonable selectivity. Permeabilities and ion fluxes through a membrane were calculated for major and interfering ions. Dependences of the transport properties of the membranes on the concentrations of the ion exchanger and near-membrane solution and their electrochemical characteristics are presented. The ISSs were used for direct potentiometry and potentiometric titration (sodium tetraphenylborate) of drotaverine hydrochloride. Results with mean accuracy of 99.1+/-1.0% of nominal were obtained which corresponded well to data obtained by use of high-performance liquid chromatography.

  19. Hole-transport properties of a low-band gap alternating polyfluorene

    Science.gov (United States)

    Debebe, Siraye E.; Mammo, Wendimagegn; Yohannes, Teketel; Tinti, Francesca; Martelli, Alessandro; Camaioni, Nadia

    2010-07-01

    The bulk transport properties of positive carriers in thin films of a low band-gap conjugated polymer, called APFO-Green5, have been investigated in the ac regime. The frequency-dependent impedance of an ITO/PEDOT:PSS/APFO-Green5/Al structure (where ITO is indium tin oxide and PEDOT:PSS is poly(3,4-ethylenedioxythiophene)/polystyrene sulphonic acid) was measured as a function of the dc applied bias. The capacitance response at low frequency gave indication of a combination of trapping and double-injection effects, while in the intermediate-high frequency range was determined by the transit time of injected holes. Hole mobility in APFO-Green5 thin films exhibited a Frenkel-like dependence on the applied electric field, with a field-dependent coefficient of around 8×10-3 (V cm-1)-1/2. A hole mobility close to 2×10-5 cm2 V-1 s-1 was achieved at the field of 3.5×105 V cm-1, in excellent agreement with that already reported by using a different bulk investigation technique.

  20. Correlation between Cohesive Energy Density, Fractional Free Volume, and Gas Transport Properties of Poly(ethylene-co-vinyl acetate Materials

    Directory of Open Access Journals (Sweden)

    Piotr Kubica

    2015-01-01

    Full Text Available The transport properties of the poly(ethylene-co-vinyl acetate (EVA materials to He, N2, O2, and CO2 are correlated with two polymer molecular structure parameters, that is, cohesive energy density (CED and fractional free volume (FFV, determined by the group contribution method. In our preceding paper, the attempt was made to approximate EVA permeability using a linear function of 1/FFV as predicted by the free volume theory. However, the deviations from this relationship appeared to be significant. In this paper, it is shown that permeation of gas molecules is controlled not only by free volume but also by the polymer cohesive energy. Moreover, the behavior of CO2 was found to differ significantly from that of other gases. In this instance, the correlation is much better when diffusivity instead of permeability is taken into account in a modified transport model.

  1. Transport properties of 2DEGs in AlGaN/GaN heterostructures: Spin splitting and occupation of higher subbands

    Energy Technology Data Exchange (ETDEWEB)

    Link, A.; Graf, T.; Stutzmann, M. [Walter Schottky Institute, Technical University Munich, Am Coulombwall 3, 85748 Garching (Germany); Ambacher, O. [Center for Micro- and Nanotechnologies, Technical University of Ilmenau, Gustav-Kirchhoff-Str 1, 8639 Ilmenau (Germany); Jimenez, A.; Calleja, E. [Dpto. Ingenieria Electronica, E.T.S.I.Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid (Spain); Smorchkova, Y.; Speck, J.; Mishra, U. [Electrical and Computer Engineering Department, College of Engineering, University of California, Santa Barbara, California 93106 (United States); Materials Department, College of Engineering, University of California, Santa Barbara, California 93106 (United States)

    2002-12-01

    To study the electronic transport properties of two-dimensional electron gases confined at the interfaces of AlGaN/GaN heterostructures, Shubnikov-de Haas (SdH) and Hall measurements were performed with structures covering a wide range of sheet carrier concentrations from 2.25 x 10{sup 12} to 1.83 x 10{sup 13} cm{sup -} {sup 2}. For samples with sheet carrier concentrations above 1.7 x 10{sup 13} cm{sup -} {sup 2}, the occupation of a second subband was observed. Fourier transformation was used to separate the contributions of both occupied subbands to the electronic transport. Quite similar quantum scattering times and effective masses of the electrons in the first and second subband were determined. In samples with lower sheet carrier concentration traces of a spin splitting could be found by investigating the angle dependence of the SdH-oscillations. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  2. Modulation of the electron transport properties in graphene nanoribbons doped with BN chains

    Directory of Open Access Journals (Sweden)

    Wu Liu

    2014-06-01

    Full Text Available Using density-functional theory and the non-equilibrium Green's function method, the electron transport properties of zigzag graphene nanoribbons (ZGNRs doped with BN chains are studied by systematically calculating the energy band structure, density of states and the transmission spectra for the systems. The BN chains destroyed the electronic transport properties of the ZGNRs, and an energy gap appeared for the ZGNRs, and displayed variations from a metal to a wide-gap semiconductor. With an increase in the number of BN chains, the band gap increased gradually in the band structure and the transmission coefficient decreased near the Fermi surface. Additionally, the doping position had a significant effect on the electronic properties of the ZGNRs.

  3. Electron transport properties in InAs four-terminal ballistic junctions under weak magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, M.; Fujiwara, K.; Amano, N.; Maemoto, T.; Sasa, S.; Inoue, M. [Nanomaterials Microdevices Research Center, Osaka Institute of Technology (JP)u, Osaka 535-8585 (Japan)

    2009-06-15

    We report on the electron transport properties based on ballistic electrons under magnetic fields in four-terminal ballistic junctions fabricated on an InAs/AlGaSb heterostructure. The four-terminal junction structure is composed of two longitudinal stems with two narrow wires slanted with 30 degree from the perpendicular axis. The electron focusing peak was obtained with the bend resistance measurement. Then it was investigated the nonlinear electron transport property of potential difference between longitudinal stems due to ballistic electrons with applying direct current from narrow wires. Observed nonlinearity showed clear rectification effects which have negative polarity regardless of input voltage polarity. Although this nonlinearity was qualitatively changed due to the Lorentz force under magnetic fields, the degradation of ballistic effects on nonlinear properties were observed when the current increased to higher strength. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Graphene transport properties upon exposure to PMMA processing and heat treatments

    DEFF Research Database (Denmark)

    Gammelgaard, Lene; Caridad, Jose; Cagliani, Alberto

    2014-01-01

    , allowing us to measure the evolution of the electrical transport properties during individual processing steps from the initial as-exfoliated to the PMMA-processed graphene. Heating generally promotes the conformation of graphene to SiO2 and is found to play a major role for the electrical properties......The evolution of graphene's electrical transport properties due to processing with the polymer polymethyl methacrylate (PMMA) and heat are examined in this study. The use of stencil (shadow mask) lithography enables fabrication of graphene devices without the usage of polymers, chemicals or heat...... of graphene while PMMA residues are found to be surprisingly benign. In accordance with this picture, graphene devices with initially high carrier mobility tend to suffer a decrease in carrier mobility, while in contrast an improvement is observed for low carrier mobility devices. We explain this by noting...

  5. Determining the potential scalability of transport interventions for improving maternal, child, and newborn health in Pakistan.

    Science.gov (United States)

    uddin Mian, Naeem; Malik, Mariam Zahid; Iqbal, Sarosh; Alvi, Muhammad Adeel; Memon, Zahid; Chaudhry, Muhammad Ashraf; Majrooh, Ashraf; Awan, Shehzad Hussain

    2015-11-25

    Pakistan is far behind in achieving the Millennium Development Goals regarding the reduction of child and maternal mortality. Amongst other factors, transport barriers make the requisite obstetric care inaccessible for women during pregnancy and at birth, when complications may become life threatening for mother and child. The significance of efficient transport in maternal and neonatal health calls for identifying which currently implemented transport interventions have potential for scalability. A qualitative appraisal of data and information about selected transport interventions generated primarily by beneficiaries, coordinators, and heads of organizations working with maternal, child, and newborn health programs was conducted against the CORRECT criteria of Credibility, Observability, Relevance, Relative Advantage, Easy-Transferability, Compatibility and Testability. Qualitative comparative analysis (QCA) techniques were used to analyse seven interventions against operational indicators. Logical inference was drawn to assess the implications of each intervention. QCA was used to determine simplifying and complicating factors to measure potential for scaling up of the selected transport intervention. Despite challenges like deficient in-journey care and need for greater community involvement, community-based ambulance services were managed with the support of the community and had a relatively simple model, and therefore had high scalability potential. Other interventions, including facility-based services, public-sector emergency services, and transport voucher schemes, had limitations of governance, long-term sustainability, large capital expenditures, and need for management agencies that adversely affected their scalability potential. To reduce maternal and child morbidity and mortality and increase accessibility of health facilities, it is important to build effective referral linkages through efficient transport systems. Effective linkages between

  6. Determinants of satisfaction with campus transportation services: Implications for service quality

    Directory of Open Access Journals (Sweden)

    Felix Charbatzadeh

    2016-01-01

    Full Text Available Background: In a number of countries, buses are a critical element of public transportation, providing the most inclusive and sustainable mode of transportation to all forms of citizenry, including staff and students of universities.Objectives: The study examines the determinants of satisfaction with campus bus transportation. The article is primarily discursive and based on the synthesis of existing service literature supported by data obtained from a survey of 847 respondents.Method: Structural equation modelling is undertaken using AMOS 19, allowing for the examination of compound relationships between service engagement variables.Results: Results show statistically significant differences between perceived service quality and travel routes. The authors argue that managerial attention to service user experiences does not only hold the key to ongoing competitive success in campus transportation services but also that those services can be significantly enriched through greater managerial attention to the interface between risk of financial loss (which increases when the campus bus transportation service provider becomes less able to compete and service quality.Conclusion: The authors argue that if providers of campus bus transportation services are to rise to their service delivery challenges and also maintain or improve upon their market positions, they must conceptualise their services in a manner that takes into consideration the two-way interrelationship between risk of financial loss and service quality. It must also be noted that, although this study may have relevance for firm–firm scenarios, its focus is primarily on service supplier firm–customer service engagements.Keywords: Modelling; Transportation; Service

  7. Correlation between AC and DC transport properties of Mn substituted cobalt ferrite

    Science.gov (United States)

    Supriya, Sweety; Kumar, Sunil; Kar, Manoranjan

    2016-12-01

    The CoFe2-xMnxO4 compound is prepared by following the sol gel technique. The structural analysis through XRD and Rietveld has been confirmed for the single cubic phase having F d 3 ¯ m space group for CoFe2-xMnxO4 and also verified it through Raman spectroscopy measurements. The tetrahedral site observed to be red shifted with increase in Mn concentration in cobalt ferrite. All the XRD patterns have been analyzed by employing the Rietveld refinement technique. The particle size was found to be in the range of 30-40 nm. The electrical properties of polycrystalline CoFe2-xMnxO4 for x = 0.00, 0.10, 0.15, and 0.2, spinel ferrite was investigated by impedance spectroscopy. The influence of doping, frequency and temperature on the electrical transport properties of the CoFe2-xMnxO4 for x = 0.00, 0.10, 0.15, and 0.20 were investigated. The magnitude of Z' and Z″ decreases with increase in temperature. Only one semicircle is observed in each Cole Cole plot which reveals that ac conductivity is dominated by grains. The grain resistance and grain boundary resistance both were found to decrease as a function of temperature. Temperature variation of DC electrical conductivity follows the Arrhenius relationship. A detailed analysis of electrical parameters provides assistance in connecting information regarding the conduction mechanism as well as determination of both dielectric and magnetic transition temperatures in the substituted cobalt ferrite. Detailed analysis of ac impedance and DC resistivity measurement reveals that, the magnetic ordering temperature in the Mn substituted cobalt ferrite does not respond to the frequency of ac electrical signal; however, it responds to the DC resistivity. The correlation between ac impedance and DC resistivity has been established.

  8. Properties of microalloyed steels used for sour gas transportation; Propiedades de aceros microaleados utilizados para el transporte de gas acido

    Energy Technology Data Exchange (ETDEWEB)

    Saldana, E.; Castro, H.; Rodriguez, C.; Belzunce, J.

    2001-07-01

    The aim of this work was to evaluate the hydrogen induced damage on the microstructure and mechanical properties of API steels (X-52 and X-65 grades). Both steels were characterized in the as-rolled state and after being submitted to NACE TM 284/87, pH 3.5, test. Microstructure, mechanical properties and fracture behaviour have been determined along with the internal cracking due to hydrogen. The appearance of these cracks were located in reference to the geometry of the plate and the way they propagate through the steel microstructure was also assessed. (Author) 6 refs.

  9. Transport properties of pyroclastic rocks from Montagne Pelée volcano (Martinique, Lesser Antilles)

    Science.gov (United States)

    Bernard, Marie-Lise; Zamora, Maria; GéRaud, Yves; Boudon, Georges

    2007-05-01

    The hydraulic and electrical properties of pyroclastic rocks have been investigated in laboratory on a representative sampling of Montagne Pelée (Martinique, France) deposits with renewed interest in geophysical applications. This sampling covers all the lithologic units of this volcano: lava dome and lava flows, pumices from ash-and-pumice fall and flow deposits, lava blocks from block-and-ash flow and Peléean "nuées ardentes" deposits, scoriae from scoria flow deposits. The connected porosity varies over a wide range from 3 to 62%. The unconnected porosity is important only on pumices where it can reach 15%. The permeability covers more than 5 orders of magnitude, ranging from 10-16 to 35 × 10-12 m2. The higher values are obtained on lava blocks and the scoriae, even if these rocks are less porous than the pumices. The formation factor ranges from 7 to 1139. The transport properties of these rocks are slightly correlated with porosity. This indicates that these properties are not only controlled by the connected porosity. To connect the transport properties to the textural characteristics of the pore network of pyroclastic rocks, different models, based on geometrical considerations or percolation theory, were tested. The pore access radius distribution and the tortuosity control the transport properties of pyroclastic rocks. Consequently, the models (electric and hydraulic) based on the concept of percolation (e.g., the models of Katz and Thompson), apply better than the equivalent channel model of Kozeny-Carman. In addition, the difference in transport properties observed on lava blocks and pumices confirms that the mechanisms of degassing and vesiculation are different for these two types of rock.

  10. Structure-dependent optical and electrical transport properties of nanostructured Al-doped ZnO.

    Science.gov (United States)

    Gondoni, P; Ghidelli, M; Di Fonzo, F; Carminati, M; Russo, V; Li Bassi, A; Casari, C S

    2012-09-14

    The structure-property relation of nanostructured Al-doped ZnO thin films has been investigated in detail through a systematic variation of structure and morphology, with particular emphasis on how they affect optical and electrical properties. A variety of structures, ranging from compact polycrystalline films to mesoporous, hierarchically organized cluster assemblies, are grown by pulsed laser deposition at room temperature at different oxygen pressures. We investigate the dependence of functional properties on structure and morphology and show how the correlation between electrical and optical properties can be studied to evaluate energy gap, conduction band effective mass and transport mechanisms. Understanding these properties opens up opportunities for specific applications in photovoltaic devices, where optimized combinations of conductivity, transparency and light scattering are required.

  11. Nanostructured ZnO films: A study of molecular influence on transport properties by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sappia, Luciano D.; Trujillo, Matias R. [Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET, Chacabuco 461, T4000ILI San Miguel de Tucumán (Argentina); Laboratorio de Medios e Interfases (LAMEIN), Departamento de Bioingeniería, Fac. de Cs. Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán (Argentina); Lorite, Israel [Division of Superconductivity and Magnetism, Institute for Experimental Physics II, University of Leipzig, Linnéstrasse 5, 04103 Leipzig (Germany); Madrid, Rossana E., E-mail: rmadrid@herrera.unt.edu.ar [Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET, Chacabuco 461, T4000ILI San Miguel de Tucumán (Argentina); Laboratorio de Medios e Interfases (LAMEIN), Departamento de Bioingeniería, Fac. de Cs. Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán (Argentina); Tirado, Monica [NanoProject and Laboratorio de Nanomateriales y Propiedades Dieléctricas, Departamento de Física, Universidad Nacional de Tucumán, Avenida Independencia 1800, Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); and others

    2015-10-15

    Graphical abstract: - Highlights: • We study electrical transport in nanostructured ZnO films by impedance spectroscopy. • Bioaggregates on the surface produce strong changes in film transport properties. • This behavior is explained by modeling data with RC parallel circuits. • Electrical responses of ZnO films to aggregates are promising for biosensing. - Abstract: Nanomaterials based on ZnO have been used to build glucose sensors due to its high isoelectric point, which is important when a protein like Glucose Oxidase (GOx) is attached to a surface. It also creates a biologically friendly environment to preserve the activity of the enzyme. In this work we study the electrical transport properties of ZnO thin films (TFs) and single crystals (SC) in contact with different solutions by using impedance spectroscopy. We have found that the composition of the liquid, by means of the charge of the ions, produces strong changes in the transport properties of the TF. The enzyme GOx and phosphate buffer solutions have the major effect in the conduction through the films, which can be explained by the entrapment of carriers at the grain boundaries of the TFs. These results can help to design a new concept in glucose biosensing.

  12. Electronic transport properties of molecular junctions based on the direct binding of aromatic ring to electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Tran Nguyen, E-mail: lantran@ims.ac.jp

    2014-01-15

    Highlights: • Transport properties of molecular junction having direct binding of aromatic ring to electrode have been investigated. • The conductance of junction with sp-type electrode is higher than that of junction with sd-type electrode. • The rectifying mechanism critically depends on the nature of benzene–electrode coupling. • The p–n junction-like can be obtained even without heteroatom doping. • The negative differential resistance effect was observed for the case of sp-type electrode. - Abstract: We have used the non-equilibrium Green’s function in combination with the density functional theory to investigate the quantum transport properties of the molecular junctions including a terminated benzene ring directly coupled to surface of metal electrodes (physisorption). The other side of molecule was connected to electrode via thiolate bond (chemisorption). Two different electrodes have been studied, namely Cu and Al. Rectification and negative differential resistance behavior have been observed. We found that the electron transport mechanism is affected by the nature of benzene–electrode coupling. In other words, the transport mechanism depends on the nature of metallic electrode. Changing from sp- to sd-metallic electrode, the molecular junction changes from the Schottky to p–n junction-like diode. The transmission spectra, projected density of state, molecular projected self-consistent Hamiltonian, transmission eigenchannel, and Muliken population have been analyzed for explanation of electronic transport properties. Understanding the transport mechanism in junction having direct coupling of π-conjugate to electrode will be useful to design the future molecular devices.

  13. Determining Transport Coefficients for a Microscopic Simulation of a Hadron Gas

    CERN Document Server

    Pratt, Scott; Kim, Jane

    2016-01-01

    Quark-Gluon plasmas produced in relativistic heavy-ion collisions quickly expand and cool, entering a phase consisting of multiple interacting hadronic resonances just below the QCD deconfinement temperature, $T\\sim 155$ MeV. Numerical microscopic simulations have emerged as the principal method for modeling the behavior of the hadronic stage of heavy-ion collisions, but the transport properties that characterize these simulations are not well understood. Methods are presented here for extracting the shear viscosity, and two transport parameters that emerge in Israel-Stewart hydrodynamics. The analysis is based on studying how the stress-energy tensor responds to velocity gradients. Results agree with expectations based on Kubo relations.

  14. Determination of the transport levels in thin films of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Krause, Stefan

    2009-07-27

    The approach of using the combination of Ultraviolet (UPS) and Inverse Photoemission (IPS) to determine the transport levels in thin films of organic semiconductors is the scope of this work. For this matter all influences on the peak position and width in Photoelectron Spectroscopy are discussed with a special focus on organic semiconductors. Many of these influences are shown with experimental results of the investigation of diindenoperylene on Ag(111). These findings are applied to inorganic semiconductors silicon in order to establish the use of UPS and IPS on a well-understood system. Finally, the method is used to determine the transport level of several organic semiconductors (PTCDA, Alq3, CuPc, DIP, PBI-H4) and the corresponding exciton binding energies are calculated by comparison to optical absorption data. (orig.)

  15. Procedure for determining transport and warehousing systems characteristics in industrial enterprises in megapolis

    Directory of Open Access Journals (Sweden)

    Radaev Anton

    2017-01-01

    Full Text Available The most common problem among a vast variety of design and performance management problems for the industrial enterprises supply chain networks is determining transport and storage processes’ characteristics in the areas of high population density. The divergence of the logistic structure development in the area has a major influence on the choice of location for the warehouses and the characteristics of the corresponding material flows. This article addresses the issues of determining transport and warehousing systems characteristics in a major population center and its suburbs. In particular, this means the warehouse location and the delivery lot sizes. The article suggests a procedure for solving this problem based on a set of mathematical models using linear and non-linear optimization via the standard algorithms of common computer software like Microsoft Excel, Mathcad, MatLab, etc.

  16. Tuning the Transport Properties of Layered Materials for Thermoelectric Applications using First-Principles Calculations

    KAUST Repository

    Saeed, Yasir

    2014-05-11

    Thermoelectric materials can convert waste heat into electric power and thus provide a way to reduce the dependence on fossil fuels. Our aim is to model the underlying materials properties and, in particular, the transport as controlled by electrons and lattice vibrations. The goal is to develop an understanding of the thermoelectric properties of selected materials at a fundamental level. The structural, electronic, optical, and phononic properties are studied in order to tune the transport, focusing on KxRhO2, NaxRhO2, PtSb2 and Bi2Se3. The investigations are based on density functional theory as implemented in the all electron linearized augmented plane wave plus local orbitals WIEN2k and pseudo potential Quantum-ESPRESSO codes. The thermoelectric properties are derived from Boltzmann transport theory under the constant relaxation time approximation, using the BoltzTraP code. We will discuss first the changes in the electronic band structure under variation of the cation concentration in layered KxRhO2 in the 2H phase and NaxRhO2 in the 3R phase. We will also study the hydrated phase. The deformations of the RhO6 octahedra turn out to govern the thermoelectric properties, where the high Seebeck coefficient results from ”pudding mold" bands. We investigate the thermoelectric properties of electron and hole doped PtSb2, which is not a layered material but shares “pudding mold" bands. PtSb2 has a high Seebeck coefficient at room temperature, which increases significantly under As alloying by bandgap opening and reduction of the lattice thermal conductivity. Bi2Se3 (bulk and thin film) has a larger bandgap then the well-known thermoelectric material Bi2Te3, which is important at high temperature. The structural stability, electronic structure, and transport properties of one to six quintuple layers of Bi2Se3 will be discussed. We also address the effect of strain on a single quintuple layer by phonon band structures. We will analyze the electronic and transport

  17. Magnetically Controlled Electronic Transport Properties of a Ferromagnetic Junction on the Surface of a Topological Insulator

    Science.gov (United States)

    Liu, Zheng-Qin; Wang, Rui-Qiang; Deng, Ming-Xun; Hu, Liang-Bin

    2015-06-01

    We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topological insulator. The current-voltage characteristic curve and the tunneling conductance are calculated theoretically. Two interesting transport features are predicted: observable negative differential conductances and linear conductances tunable from unit to nearly zero. These features can be magnetically manipulated simply by changing the spacial orientation of the magnetization. Our results may contribute to the development of high-speed switching and functional applications or electrically controlled magnetization switching. Supported by National Natural Science Foundation of China under Grant Nos. 11174088, 11175067, 11274124

  18. Vibrational energy transport in molecules and the statistical properties of vibrational modes

    Science.gov (United States)

    Pandey, Hari Datt; Leitner, David M.

    2017-01-01

    Statistical properties of the eigenmodes computed for two molecules, dodecane and perfluorododecane, are examined and compared with predictions of random matrix theory. The eigenmode statistics of the heat carrying modes of perfluorododecane correspond to Porter-Thomas statistics, whereas those for dodecane do not. Vibrational energy transport in the two molecules is also computed and found to be diffusive in perfluorododecane but not in dodecane, consistent with recent experiments. The correspondence between eigenmode statistics and vibrational energy transport dynamics in molecules as well as thermalization in molecules are discussed.

  19. Synthesis and quantum transport properties of Bi₂Se₃ topological insulator nanostructures.

    Science.gov (United States)

    Yan, Yuan; Liao, Zhi-Min; Zhou, Yang-Bo; Wu, Han-Chun; Bie, Ya-Qing; Chen, Jing-Jing; Meng, Jie; Wu, Xiao-Song; Yu, Da-Peng

    2013-01-01

    Bi₂Se₃ nanocrystals with various morphologies, including nanotower, nanoplate, nanoflake, nanobeam and nanowire, have been synthesized. Well-distinguished Shubnikov-de Haas (SdH) oscillations were observed in Bi₂Se₃ nanoplates and nanobeams. Careful analysis of the SdH oscillations suggests the existence of Berry's phase π, which confirms the quantum transport of the surface Dirac fermions in both Bi₂Se₃ nanoplates and nanobeams without intended doping. The observation of the singular quantum transport of the topological surface states implies that the high-quality Bi₂Se₃ nanostructures have superiorities for investigating the novel physical properties and developing the potential applications.

  20. Poly(o-aminophenol) film electrodes synthesis, transport properties and practical applications

    CERN Document Server

    Tucceri, Ricardo

    2014-01-01

    This review book is concerned with the synthesis, charge transport properties and practical applications of poly (o-aminophenol) (POAP) film electrodes. It is divided into three parts. The first one has a particular emphasis on problems of synthesis and structure of POAP. The second part deals with the mechanism of charge transfer and charge transport processes occurring in the course of the redox reactions of POAP. The third part describes the promising applications of POAP in the different fields of sensors, electrocatalysis, bioelectrochemistry, corrosion protection, among others. This review covers the literature on POAP in the time period comprised between 1987 and 2013.

  1. Charge transport and memristive properties of graphene quantum dots embedded in poly(3-hexylthiophene) matrix

    Energy Technology Data Exchange (ETDEWEB)

    Cosmin Obreja, Alexandru; Cristea, Dana; Radoi, Antonio; Gavrila, Raluca; Comanescu, Florin; Kusko, Cristian, E-mail: cristian.kusko@imt.ro [National Institute for R and D in Microtechnologies, 72996, Bucharest (Romania); Mihalache, Iuliana [National Institute for R and D in Microtechnologies, 72996, Bucharest (Romania); Physics Department, University Bucharest, P.O. Box MG-11, 077125 Bucharest (Romania)

    2014-08-25

    We show that graphene quantum dots (GQD) embedded in a semiconducting poly(3-hexylthiophene) polymeric matrix act as charge trapping nanomaterials. In plane current-voltage (I-V) measurements of thin films realized from this nanocomposite deposited on gold interdigitated electrodes revealed that the GQD enhanced dramatically the hole transport. I-V characteristics exhibited a strong nonlinear behavior and a pinched hysteresis loop, a signature of a memristive response. The transport properties of this nanocomposite were explained in terms of a trap controlled space charge limited current mechanism.

  2. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    Science.gov (United States)

    Denjean, C.; Cassola, F.; Mazzino, A.; Triquet, S.; Chevaillier, S.; Grand, N.; Bourrianne, T.; Momboisse, G.; Sellegri, K.; Schwarzenbock, A.; Freney, E.; Mallet, M.; Formenti, P.

    2016-02-01

    This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals

  3. Quantum Size Effects in Transport Properties of Bi2Te3 Topological Insulator Thin Films

    Science.gov (United States)

    Rogacheva, E. I.; Budnik, A. V.; Nashchekina, O. N.; Meriuts, A. V.; Dresselhaus, M. S.

    2017-07-01

    Bi2Te3 compound and Bi2Te3-based solid solutions have attracted much attention as promising thermoelectric materials for refrigerating devices. The possibility of enhancing the thermoelectric efficiency in low-dimensional structures has stimulated studies of Bi2Te3 thin films. Now, interest in studying the transport properties of Bi2Te3 has grown sharply due to the observation of special properties characteristic of three-dimensional (3D) topological insulators in Bi2Te3. One of the possible manifestations of quantum size effects in two-dimensional structures is an oscillatory behavior of the dependences of transport properties on film thickness, d. The goal of this work is to summarize our earlier experimental results on the d-dependences of transport properties of Bi2Te3 thin films obtained by thermal evaporation in a vacuum on glass substrates, and to present our new results of theoretical calculations of the oscillations periods within the framework of the model of an infinitely deep potential well, which takes into account the dependence of the Fermi energy on d and the contribution of all energy subbands below the Fermi level to the conductivity. On the basis of the data obtained, some general regularities and specificity of the quantum size effects manifestation in 3D topological insulators are established.

  4. Calculation of thermodynamic and transport properties of thermal plasmas based on the Cantera software toolkit

    Science.gov (United States)

    Doiron, Charles; Hencken, Kai

    2013-09-01

    Computational fluid-dynamic simulations nowadays play a central role in the development of new gas circuit breakers. For these simulations to be reliable, a good knowledge of the pressure and temperature-dependence of the thermodynamic and transport properties of ionized gases is required. A key ingredient in the calculation of thermodynamic properties of thermal plasmas is the calculation of the chemical equilibrium composition of the gas. The general-purpose, open-source software toolkit Cantera provides most functionality required to carry out such thermodynamic calculations. In this contribution, we explain how we tailored Cantera specifically to calculate material properties of plasmas. The highly modular architecture of this framework made it possible to add support for Debye-Hückel non-ideality corrections in the calculation of the chemical equilibrium mixture, as well as to enable the calculation of the key transport parameters needed in CFD-based electric arc simulations: electrical and thermal conductivity, viscosity, and diffusion coefficients. As an example, we discuss the thermodynamic and transport properties of mixtures of carbon dioxide and copper vapor.

  5. 36 CFR 18.4 - What determinations must the Director make before leasing property?

    Science.gov (United States)

    2010-07-01

    ... Director make before leasing property? 18.4 Section 18.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR LEASING OF PROPERTIES IN PARK AREAS § 18.4 What determinations must the Director make before leasing property? Before leasing property in a park area under this part,...

  6. Binding Mode Selection Determines the Action of Ecstasy Homologs at Monoamine Transporters.

    Science.gov (United States)

    Sandtner, Walter; Stockner, Thomas; Hasenhuetl, Peter S; Partilla, John S; Seddik, Amir; Zhang, Yuan-Wei; Cao, Jianjing; Holy, Marion; Steinkellner, Thomas; Rudnick, Gary; Baumann, Michael H; Ecker, Gerhard F; Newman, Amy Hauck; Sitte, Harald H

    2016-01-01

    Determining the structural elements that define substrates and inhibitors at the monoamine transporters is critical to elucidating the mechanisms underlying these disparate functions. In this study, we addressed this question directly by generating a series of N-substituted 3,4-methylenedioxyamphetamine analogs that differ only in the number of methyl substituents on the terminal amine group. Starting with 3,4-methylenedioxy-N-methylamphetamine, 3,4-methylenedioxy-N,N-dimethylamphetamine (MDDMA) and 3,4-methylenedioxy-N,N,N-trimethylamphetamine (MDTMA) were prepared. We evaluated the functional activities of the compounds at all three monoamine transporters in native brain tissue and cells expressing the transporters. In addition, we used ligand docking to generate models of the respective protein-ligand complexes, which allowed us to relate the experimental findings to available structural information. Our results suggest that the 3,4-methylenedioxyamphetamine analogs bind at the monoamine transporter orthosteric binding site by adopting one of two mutually exclusive binding modes. 3,4-methylenedioxyamphetamine and 3,4-methylenedioxy-N-methylamphetamine adopt a high-affinity binding mode consistent with a transportable substrate, whereas MDDMA and MDTMA adopt a low-affinity binding mode consistent with an inhibitor, in which the ligand orientation is inverted. Importantly, MDDMA can alternate between both binding modes, whereas MDTMA exclusively binds to the low-affinity mode. Our experimental results are consistent with the idea that the initial orientation of bound ligands is critical for subsequent interactions that lead to transporter conformational changes and substrate translocation.

  7. Correlation of microstructure and thermo-mechanical properties of a novel hydrogen transport membrane

    Science.gov (United States)

    Zhang, Yongjun

    A key part of the FutureGen concept is to support the production of hydrogen to fuel a "hydrogen economy," with the use of clean burning hydrogen in power-producing fuel cells, as well as for use as a transportation fuel. One of the key technical barriers to FutureGen deployment is reliable and efficient hydrogen separation technology. Most Hydrogen Transport Membrane (HTM) research currently focuses on separation technology and hydrogen flux characterization. No significant work has been performed on thermo-mechanical properties of HTMs. The objective of the thesis is to understand the structure-property correlation of HTM and to characterize (1) thermo mechanical properties under different reducing environments and thermal cycles (thermal shock), and (2) evaluate the stability of the novel HTM material. A novel HTM cermet bulk sample was characterized for its physical and mechanical properties at both room temperature and at elevated temperature up to 1000°C. Micro-structural properties and residual stresses were evaluated in order to understand the changing mechanism of the microstructure and its effects on the mechanical properties of materials. A correlation of the microstructural and thermo mechanical properties of the HTM system was established for both HTM and the substrate material. Mechanical properties of both selected structural ceramics and the novel HTM cermet bulk sample are affected mainly by porosity and microstructural features, such as grain size and pore size-distribution. The Young's Modulus (E-value) is positively correlated to the flexural strength for materials with similar crystallographic structure. However, for different crystallographic materials, physical properties are independent of mechanical properties. Microstructural properties, particularly, grain size and crystallographic structure, and thermodynamic properties are the main factors affecting the mechanical properties at both room and high temperatures. The HTM cermet behaves

  8. Stochastic reconstruction and a scaling method to determine effective transport coefficients of a proton exchange membrane fuel cell catalyst layer

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, R. [Centro de Investigacion en Energia, UNAM, Privada Xochicalco S/N, 62580 Temixco (Mexico); Andaverde, J. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, UAEM, Av. Universidad 1001, Col. Chamilpa, 62210 Cuernavaca (Mexico); Escobar, B. [Instituto Tecnologico de Cancun, Av. Kabah 3, 77515 Cancun (Mexico); Cano, U. [Instituto de Investigaciones Electricas, Av. Reforma 113, col. Palmira, 62490 Cuernavaca (Mexico)

    2011-02-01

    This work uses a method for the stochastic reconstruction of catalyst layers (CLs) proposing a scaling method to determine effective transport properties in proton exchange membrane fuel cell (PEMFC). The algorithm that generates the numerical grid makes use of available information before and after manufacturing the CL. The structures so generated are characterized statistically by two-point correlation functions and by the resultant pore size distribution. As an example of this method, the continuity equation for charge transport is solved directly on the three-dimensional grid of finite control volumes (FCVs), to determine effective electrical and proton conductivities of different structures. The stochastic reconstruction and the electrical and proton conductivity of a 45 {mu}m side size cubic sample of a CL, represented by more than 3.3 x 10{sup 12} FVCs were realized in a much shorter time compared with non-scaling methods. Variables studied in an example of CL structure were: (i) volume fraction of dispersed electrolyte, (ii) total CL porosity and (iii) pore size distribution. Results for the conduction efficiency for this example are also presented. (author)

  9. Structural determinants of NH3 and NH4+ transport by mouse Rhbg, a renal Rh glycoprotein.

    Science.gov (United States)

    Abdulnour-Nakhoul, Solange; Le, Trang; Rabon, Edd; Hamm, L Lee; Nakhoul, Nazih L

    2016-12-01

    Renal Rhbg is localized to the basolateral membrane of intercalated cells and is involved in NH3/NH4(+) transport. The structure of Rhbg is not yet resolved; however, a high-resolution crystal structure of AmtB, a bacterial homolog of Rh, has been determined. We aligned the sequence of Rhbg to that of AmtB and identified important sites of Rhbg that may affect transport. Our analysis positioned three conserved amino acids, histidine 183 (H183), histidine 342 (H342), and tryptophan 230 (W230), within the hydrophobic pore where they presumably serve to control NH3 transport. A fourth residue, phenylalanine 128 (F128) was positioned at the upper vestibule, presumably contributing to recruitment of NH4(+) We generated three mutations each of H183, H342, W230, and F128 and expressed them in frog oocytes. Immunolabeling showed that W230 and F128 mutants were localized to the cell membrane, whereas H183 and H342 staining was diffuse and mostly intracellular. To determine function, we compared measurements of NH3/NH4(+) and methyl amine (MA)/methyl ammonium (MA(+))-induced currents, intracellular pH, and surface pH (pHs) among oocytes expressing the mutants, Rhbg, or injected with H2O. In H183 and W230 mutants, NH4(+)-induced current and intracellular acidification were inhibited compared with that of Rhbg, and MA-induced intracellular alkalinization was completely absent. Expression of H183A or W230A mutants inhibited NH3/NH4(+)- and MA/MA(+)-induced decrease in pHs to the level observed in H2O-injected oocytes. Mutations of F128 did not significantly affect transport of NH3 or NH4(+) These data demonstrated that mutating H183 or W230 caused loss of function but not F128. H183 and H342 may affect membrane expression of the transporter.

  10. CHARACTERIZATION OF NATURAL ZEOLITE AND DETERMINATION ITS ADSORPTION PROPERTIES

    Directory of Open Access Journals (Sweden)

    Marian HOLUB

    Full Text Available Pollution of water by toxic substances is one of the major reason concerning human health as well as the environmental quality. In terms of pollution, mining activities represent a serious threat. Countries of the middle Europe, where extraction of mineral resources takes place a long period, have to solve the problems of wastewater containing whole spectra of heavy metals, which are dangerous to the environment. Finding of the new and cheap ways of wastewater contaminated by heavy metals treatment can increase the quality of the environment in the affected localities and thus prevent adverse effects on fauna, flora or human beings. Sorption techniques belong to a cost effective methods that are able to effectively remove heavy metals. For the overall understanding of the sorption process, it is necessary to characterize and determine the properties of the used adsorbents. The paper deals with characterization of natural zeolite before and after sorption process under acidic conditions. The zeolite was characterized using Fourier transform infrared spectroscopy, X – ray diffraction, scanning electron microscopy and N2 adsorption/desorption isotherms.

  11. Calibrated sky imager for aerosol optical properties determination

    Directory of Open Access Journals (Sweden)

    A. Cazorla

    2008-11-01

    Full Text Available The calibrated ground-based sky imager developed in the Marine Physical Laboratory, the Whole Sky Imager (WSI, has been tested to determine optical properties of the atmospheric aerosol. Different neural network-based models calculate the aerosol optical depth (AOD for three wavelengths using the radiance extracted from the principal plane of sky images from the WSI as input parameters. The models use data from a CIMEL CE318 photometer for training and validation and the wavelengths used correspond to the closest wavelengths in both instruments. The spectral dependency of the AOD, characterized by the Ångström exponent α in the interval 440–870, is also derived using the standard AERONET procedure and also with a neural network-based model using the values obtained with a CIMEL CE318. The deviations between the WSI derived AOD and the AOD retrieved by AERONET are within the nominal uncertainty assigned to the AERONET AOD calculation (±0.01, in 80% of the cases. The explanation of data variance by the model is over 92% in all cases. In the case of α, the deviation is within the uncertainty assigned to the AERONET α (±0.1 in 50% for the standard method and 84% for the neural network-based model. The explanation of data variance by the model is 63% for the standard method and 77% for the neural network-based model.

  12. Three perspectives on bedload transport at a sandy gravel beach (Advocate Harbour, Nova Scotia) with focus on sediment properties

    Science.gov (United States)

    Stark, N.; Hay, A. E.; Guest, T.; Hatcher, M. G.; Cheel, R. A.; Barclay, D. J.; Zedel, L. J.; Lake, C. B.

    2012-12-01

    Bedload transport is the major transport mode for coarse sediment in coastal zones. Understanding its mechanisms requires knowledge of the driving force (hydrodynamics), the stabilizing force (sediment properties), and the bed characteristics (bed roughness, bed slope, bedforms). During a 3-week-long field experiment at Advocate Beach, Nova Scotia, bedload transport was targeted from three perspectives: (i) The water column: using a new acoustic Doppler profiler (MFDop), 3D flow velocities were monitored to assess bed shear stress over a range of conditions. Additionally, sediment concentrations close to the bed (~10 cm) were determined by water sampling under calm conditions (0.15-0.6 g/l) and within the shorebreak (1-50 g/l). (ii) The bed: rotary sonars were used to observe the development of ripples and bed elevation change as a measure of ongoing sediment transport. Also, the net displacement of 20 marked cobbles on the seabed surface was measured, revealing significant changes in transport direction and distance (ranging from 0 to 50 m). (iii) The sediment properties: grain size ranged from medium sand to small cobbles. The finer-grained particles were rounded, but showed an elliptic to plate-like shape. Grain size distributions varied significantly across the shoreface as well as under different hydrodynamic conditions. Observed beach cusps were strongly sorted (coarse pebbles at the horns, coarse sand in the bays). Direct shear tests were carried out to determine peak shear strengths of the sediment and friction angles. Peak shear strengths under low normal stress (0.47 kPa) can be compared best to surficial sediment conditions, and did not exceed 9 kPa in the case of the sands. The sediment showed a surprisingly strong dilative behavior during shearing and high friction angles considering the grain size, the low load and low density conditions during the tests. Thus, grain shape and the particle re-organization under shearing played important roles. Finally

  13. Estimation of fluid flow and mass transport properties in a natural fracture using laboratory testing system on mass transport in fractured rock (LABROCK)

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, Naoto; Uchida, Masahiro [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai, Ibaraki (Japan); Satou, Hisashi [Inspection Development Company Ltd., Tokai, Ibaraki (Japan)

    2003-03-01

    The understanding of mass transport and fluid flow properties in natural rock fractures is important for safety assessment of geological disposal of high level nuclear waste. The authors developed advanced tracer test equipment in which a 50-cm cubic scale rock sample was feasible. The mass transport and fluid flow properties in a single fracture were also examined. The relation among hydraulic, transport and mass balance apertures of a natural single fracture were obtained. Heterogeneity of the aperture distribution was evident, as was the possibility of some major flow line perpendicular to the flow direction. Additionally, the relation between normal stress and each aperture was also obtained by loading normal stress on the fracture. In future, measuring the aperture distribution and establishing the model considering fluid flow and mass transport properties in natural rock fractures will be conducted. (author)

  14. Electron Density Determination, Bonding and Properties of Tetragonal Ferromagnetic Intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Wiezorek, Jorg [Univ. of Pittsburgh, PA (United States)

    2016-09-01

    The project developed quantitative convergent-beam electron diffraction (QCBED) methods by energy-filtered transmission electron microscopy (EFTEM) and used them in combination with density functional theory (DFT) calculations to study the electron density distribution in metallic and intermetallic phases with different cubic and non-cubic crystal structures that comprise elements with d-electron shells. The experimental methods developed here focus on the bonding charge distribution as one of the quantum mechanical characteristics central for understanding of intrinsic properties and validation of DFT calculations. Multiple structure and temperature factors have been measured simultaneously from nano-scale volumes of high-quality crystal with sufficient accuracy and precision for comparison with electron density distribution calculations by DFT. The often anisotropic temperature factors for the different atoms and atom sites in chemically ordered phases can differ significantly from those known for relevant pure element crystals due to bonding effects. Thus they have been measured from the same crystal volumes from which the structure factors have been determined. The ferromagnetic ordered intermetallic phases FePd and FePt are selected as model systems for 3d-4d and 3d-5d electron interactions, while the intermetallic phases NiAl and TiAl are used to probe 3d-3p electron interactions. Additionally, pure transition metal elements with d-electrons have been studied. FCC metals exhibit well defined delocalized bonding charge in tetrahedral sites, while less directional, more distributed bonding charge attains in BCC metals. Agreement between DFT calculated and QCBED results degrades as d-electron levels fill in the elements, and for intermetallics as d-d interactions become prominent over p-d interactions. Utilizing the LDA+U approach enabled inclusion of onsite Coulomb-repulsion effects in DFT calculations, which can afford improved agreements with QCBED results

  15. Interactive FORTRAN IV computer programs for the thermodynamic and transport properties of selected cryogens (fluids pack)

    Science.gov (United States)

    Mccarty, R. D.

    1980-01-01

    The thermodynamic and transport properties of selected cryogens had programmed into a series of computer routines. Input variables are any two of P, rho or T in the single phase regions and either P or T for the saturated liquid or vapor state. The output is pressure, density, temperature, entropy, enthalpy for all of the fluids and in most cases specific heat capacity and speed of sound. Viscosity and thermal conductivity are also given for most of the fluids. The programs are designed for access by remote terminal; however, they have been written in a modular form to allow the user to select either specific fluids or specific properties for particular needs. The program includes properties for hydrogen, helium, neon, nitrogen, oxygen, argon, and methane. The programs include properties for gaseous and liquid states usually from the triple point to some upper limit of pressure and temperature which varies from fluid to fluid.

  16. A Review of Hydrothermal Liquefaction Bio-Crude Properties and Prospects for Upgrading to Transportation Fuels

    Directory of Open Access Journals (Sweden)

    Jerome A. Ramirez

    2015-07-01

    Full Text Available Hydrothermal liquefaction (HTL presents a viable route for converting a vast range of materials into liquid fuel, without the need for pre-drying. Currently, HTL studies produce bio-crude with properties that fall short of diesel or biodiesel standards. Upgrading bio-crude improves the physical and chemical properties to produce a fuel corresponding to diesel or biodiesel. Properties such as viscosity, density, heating value, oxygen, nitrogen and sulphur content, and chemical composition can be modified towards meeting fuel standards using strategies such as solvent extraction, distillation, hydrodeoxygenation and catalytic cracking. This article presents a review of the upgrading technologies available, and how they might be used to make HTL bio-crude into a transportation fuel that meets current fuel property standards.

  17. Evaluation of collective transport properties of ionic melts from molecular dynamics simulations

    Indian Academy of Sciences (India)

    Manish Agarwal; Charusita Chakravarty

    2009-09-01

    Molecular dynamics simulations of beryllium fluoride (BeF2) have been carried out in the canonical (NVT) ensemble using a rigid-ion potential model. The Green-Kubo formalism has been applied to compute viscosities and ionic conductivities of BeF2 melt. The computational parameters critical for reliably estimating these collective transport properties are shown to differ significantly for viscosity and ionic conductivity. In addition to the equilibrium values of these transport properties, structural relaxation times as well as high-frequency IR-active modes are computed from the pressure and charge-flux auto correlation functions (ACFs) respectively. It is shown that a network-forming ionic melt, such as BeF2, will display persistent oscillatory behaviour of the integral of the charge-flux ACF. By suitable Fourier transformation, one can show that these persistent oscillations correspond to highfrequency, infra-red active vibrations associated with local modes of the network.

  18. Ab initio study of transport properties in defected carbon nanotubes: an O(N) approach

    Energy Technology Data Exchange (ETDEWEB)

    Biel, Blanca; GarcIa-Vidal, F J; Flores, Fernando [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Rubio, Angel [European Theoretical Spectroscopy Facility (ETSF), Departamento de Fisica de Materiales, Universidad PaIs Vasco, Edificio Korta, Avenida Tolosa 72, 20018 San Sebastian (Spain)], E-mail: blanca.biel@cea.fr

    2008-07-23

    A combination of ab initio simulations and linear-scaling Green's functions techniques is used to analyze the transport properties of long (up to 1 {mu}m) carbon nanotubes with realistic disorder. The energetics and the influence of single defects (monovacancies and divacancies) on the electronic and transport properties of single-walled armchair carbon nanotubes are analyzed as a function of the tube diameter by means of the local orbital first-principles Fireball code. Efficient O(N) Green's functions techniques framed within the Landauer-Buettiker formalism allow a statistical study of the nanotube conductance averaged over a large sample of defected tubes and thus extraction of the nanotube localization length. The cases of zero and room temperature are both addressed.

  19. Crystallization and Transport Properties of Amorphous Cr-Si Thin Film Thermoelectrics

    Science.gov (United States)

    Novikov, S. V.; Burkov, A. T.; Schumann, J.

    2014-06-01

    We studied the thermoelectric properties, crystallization, and stability of amorphous and nanocrystalline states in Cr-Si composite films. Amorphous films, prepared by magnetron sputtering, were transformed into the nanocrystalline state by annealing with in situ thermopower and electrical resistivity measurements. We have found that the amorphous state is stable in these film composites to about 550 K. Prior to crystallization, the amorphous films undergo a structural relaxation, detected by peculiarities in the temperature dependences of the transport properties, but not visible in x-ray or electron diffraction. The magnitude and temperature dependences of electrical conductivity and thermopower indicate that electron transport in the amorphous films is through extended states. The amorphous films are crystallized at annealing temperatures above 550 K into a nanocrystalline composite with an average grain size of 10-20 nm.

  20. Crystal structure and electrical transport properties of single layered perovskite LaSrCoO4

    Science.gov (United States)

    Ahad, Abdul; Shukla, D. K.; Rahman, F.; Majid, S.; Tarachand; Okram, G. S.; Phase, D. M.

    2016-10-01

    We present here investigations on the influence of structure on electrical transport properties of polycrystalline LaSrCoO4 that is single layered perovskite with K2NiF4 type structure synthesized using solid state reaction route. Using Reitveld refinement of X-ray diffraction (XRD) data, it is found that the sample is in single phase with tetragonal structure (space group I4/mmm). Electrical resistivity performed in the temperature range 140-300K shows semiconducting character of the sample. Considerable contrasts in the Co-O bond length is associated with the intermediate spin (IS) state of Co ion that correlates the structural and transport properties. Detailed analysis indicates that the temperature dependent electrical resistivity follows the three-dimensional variable range hopping (VRH) model in low temperature region below 225K. The high temperature (225-300K) resistivity data has been found to follow the thermally activated behaviour.

  1. Theoretical study of electronic transport properties of a graphene-silicene bilayer

    Science.gov (United States)

    Berdiyorov, G. R.; Bahlouli, H.; Peeters, F. M.

    2015-06-01

    Electronic transport properties of a graphene-silicene bilayer system are studied using density-functional theory in combination with the nonequilibrium Green's function formalism. Depending on the energy of the electrons, the transmission can be larger in this system as compared to the sum of the transmissions of separated graphene and silicene monolayers. This effect is related to the increased electron density of states in the bilayer sample. At some energies, the electronic states become localized in one of the layers, resulting in the suppression of the electron transmission. The effect of an applied voltage on the transmission becomes more pronounced in the layered sample as compared to graphene due to the larger variation of the electrostatic potential profile. Our findings will be useful when creating hybrid nanoscale devices where enhanced transport properties will be desirable.

  2. On the statistical and transport properties of a non-dissipative Fermi-Ulam model

    Energy Technology Data Exchange (ETDEWEB)

    Livorati, André L. P. [Departamento de Física, UNESP - Univ. Estadual Paulista, Ave. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Instituto de Física, IFUSP - Universidade de São Paulo, Rua do Matão, Tr.R 187, Cidade Universitária, 05314-970 São Paulo, SP (Brazil); School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Dettmann, Carl P. [School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Caldas, Iberê L. [Instituto de Física, IFUSP - Universidade de São Paulo, Rua do Matão, Tr.R 187, Cidade Universitária, 05314-970 São Paulo, SP (Brazil); Leonel, Edson D. [Departamento de Física, UNESP - Univ. Estadual Paulista, Ave. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste (Italy)

    2015-10-15

    The transport and diffusion properties for the velocity of a Fermi-Ulam model were characterized using the decay rate of the survival probability. The system consists of an ensemble of non-interacting particles confined to move along and experience elastic collisions with two infinitely heavy walls. One is fixed, working as a returning mechanism of the colliding particles, while the other one moves periodically in time. The diffusion equation is solved, and the diffusion coefficient is numerically estimated by means of the averaged square velocity. Our results show remarkably good agreement of the theory and simulation for the chaotic sea below the first elliptic island in the phase space. From the decay rates of the survival probability, we obtained transport properties that can be extended to other nonlinear mappings, as well to billiard problems.

  3. The influence of inner hydrophobisation on water transport properties of modified lime plasters

    Science.gov (United States)

    Pavlíková, Milena; Pavlík, Zbyšek; Pernicová, Radka; Černý, Robert

    2016-06-01

    The effect of hydrophobic agent admixture on water vapour and liquid water transport properties of newly designed lime plasters is analysed in the paper. The major part of physico - chemical building deterioration is related to the penetration of moisture and soluble salts into the building structure. For that reason, the modified lime plasters were in the broad range of basic material properties tested. From the quantitative point of view, the measured results clearly demonstrate the big differences in the behaviour of studied materials depending on applied modifying admixtures. From the practical point of view, plaster made of lime hydrate, metakaolin, zinc stearate and air-entraining agent can be recommended for renovation purposes. The accessed material parameters will be used as input data for computational modelling of moisture transport in this type of porous building materials and will be stored in material database.

  4. Electronic structure and transport properties of the Heusler compound Co{sub 2}TiAl

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Tanja; Fecher, Gerhard H; Barth, Joachim; Winterlik, Juergen; Felser, Claudia, E-mail: fecher@uni-mainz.d [Johannes Gutenberg Universitaet, Institut fuer Analytische und Anorganische Chemie, 55099 Mainz (Germany)

    2009-04-21

    The properties of the Heusler compound Co{sub 2}TiAl were investigated in detail by experimental techniques and theoretical methods. X-ray diffraction measurements indicate that as-cast samples of the compound exhibit the L2{sub 1} structure with a small amount of B2-type disorder. This leads to a reduced saturation magnetization per formula unit of 0.747 {mu}{sub B}. The Curie temperature is approximately 120 K. The transport properties are influenced by the change in the electronic structure at the Curie temperature, as revealed experimentally by conductivity, thermal transport and specific heat measurements. Different theoretical models based on ab initio calculations of the electronic structure are used to explain the experimental observations.

  5. Transport properties of boron-doped single-walled silicon carbide nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.T. [Key laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Ding, R.X., E-mail: rx_ding@163.co [Key laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Song, J.X. [Key laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); School of Electronic Engineering, Xi' an Shiyou University, Xi' an 710075 (China)

    2011-01-15

    The doped boron (B) atom in silicon carbide nanotube (SiCNT) can substitute carbon or silicon atom, forming two different structures. The transport properties of both B-doped SiCNT structures are investigated by the method combined non-equilibrium Green's function with density functional theory (DFT). As the bias ranging from 0.8 to 1.0 V, the negative differential resistance (NDR) effect occurs, which is derived from the great difficulty for electrons tunneling from one electrode to another with the increasing of localization of molecular orbital. The high similar transport properties of both B-doped SiCNT indicate that boron is a suitable impurity for fabricating nano-scale SiCNT electronic devices.

  6. Magnetization and electric transport properties of single-crystal MgB2 nanowires.

    Science.gov (United States)

    Wu, Cen-Shawn; Chang, Yu-Cheng; Chen, Weimeng; Chen, Chinping; Feng, Qingrong

    2012-11-23

    High quality single-crystal magnesium diboride (MgB(2)) nanowires with lengths exceeding 10 μm were successfully synthesized by hybrid physical chemical vapor deposition. The magnetization and electrical transport properties of single-crystal MgB(2) nanowires (NWs) were measured. The superconducting transition temperature of the NWs was 37 K, as confirmed by magnetization measurements. The disordered behavior of the nanowires was observed by four-terminal current-voltage characteristic measurements of an individual NW from T = 10 to 300 K. The temperature-dependent resistivity curves for seven NWs collapsed into a universal curve described by the variable range hopping model, showing intrinsic nonmetallic transport properties. This implies that the granular superconducting defect states are critical to the superconductivity of the individual MgB(2) NWs.

  7. Thermal transport properties of thermally sprayed coatings: An integrated study of materials, processing and microstructural effects

    Science.gov (United States)

    Chi, Weiguang

    The complex microstructures of thermally sprayed coatings are very sensitive to processing conditions and have a significant influence on the properties. The thermal transport property is a very important design parameter for thermally sprayed coatings. Despite considerable progress in this area, there is continued need to clarify the interrelationships among processing, microstructure and thermal transport properties. This has been enabled through continued advancements in processing science and control, enhancements in microstructural characterization and new methods of property characterization. The purpose of this research is to seek a successive pathway to prior efforts in understanding the effect of microstructural defects on the thermal transport property of thermally sprayed coatings. Relationship between microstructure and thermal conductivity is investigated for three sets of plasma sprayed yttria stabilized zirconia (YSZ) coating systems made using different morphology powders, different particle size distribution and controlled modification of particle states via plasma torch parameters. By integrating the results, maps of the thermal conductivity-porosity relationship have been established. Such maps highlight the role of splat thickness and interfaces in thermal conductivity. Furthermore, a new microstructural parameter termed "effective porosity" is proposed which considers the dominating role of interlamellar pores on through thickness thermal transport in thermally sprayed coatings. This effective porosity is rationalized based on the heat transport mechanism and enables better understanding of microstructure-thermal transport property correlation. An inverse linear model and a percolation model are established which can serve as predictive tools for understanding microstructure-thermal conductivity relationships. In addition, a systematic assessment of thermal conductivity anisotropy has been carried out for YSZ, Al2O 3 and several metallic

  8. Theoretical study of electronic transport properties of a graphene-silicene bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Berdiyorov, G. R. [Qatar Environment and Energy Research Institute, Qatar Foundation, P.O. Box 5825, Doha (Qatar); Bahlouli, H. [Department of Physics, King Fahd University of Petroleum and Minerals, 31261 Dhahran (Saudi Arabia); Saudi Center for Theoretical Physics, 31261 Dhahran (Saudi Arabia); Peeters, F. M. [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2015-06-14

    Electronic transport properties of a graphene-silicene bilayer system are studied using density-functional theory in combination with the nonequilibrium Green's function formalism. Depending on the energy of the electrons, the transmission can be larger in this system as compared to the sum of the transmissions of separated graphene and silicene monolayers. This effect is related to the increased electron density of states in the bilayer sample. At some energies, the electronic states become localized in one of the layers, resulting in the suppression of the electron transmission. The effect of an applied voltage on the transmission becomes more pronounced in the layered sample as compared to graphene due to the larger variation of the electrostatic potential profile. Our findings will be useful when creating hybrid nanoscale devices where enhanced transport properties will be desirable.

  9. Transport Properties of Amine/Carbon Dioxide Reactive Mixtures and Implications to Carbon Capture Technologies.

    Science.gov (United States)

    Turgman-Cohen, Salomon; Giannelis, Emmanuel P; Escobedo, Fernando A

    2015-08-19

    The structure and transport properties of physisorbed and chemisorbed CO2 in model polyamine liquids (hexamethylenediamine and diethylenetriamine) are studied via molecular dynamics simulations. Such systems are relevant to CO2 absorption processes where nonaqueous amines are used as absorbents (e.g., when impregnated or grafted onto mesoporous media or misted in the gas phase). It is shown that accounting for the ionic speciation resulting from CO2 chemisorption enabled us to capture the qualitative changes in extent of absorption and fluidity with time that are observed in thermogravimetric experiments. Simulations reveal that high enough concentration of reacted CO2 leads to strong intermolecular ionic interactions and the arrest of molecular translations. The transport properties obtained from the simulations of the ionic speciated mixtures are also used to construct an approximate continuum-level model for the CO2 absorption process that mimics thermogravimetric experiments.

  10. Electronic and transport properties of a molecular junction with asymmetric contacts

    Science.gov (United States)

    Tsai, M.-H.; Lu, T.-H.

    2010-02-01

    Asymmetric molecular junctions have been shown experimentally to exhibit a dual-conductance transport property with a pulse-like current-voltage characteristic, by Reed and co-workers. Using a recently developed first-principles integrated piecewise thermal equilibrium current calculation method and a gold-benzene-1-olate-4-thiolate-gold model molecular junction, this unusual transport property has been reproduced. Analysis of the electrostatics and the electronic structure reveals that the high-current state results from subtle bias induced charge transfer at the electrode-molecule contacts that raises molecular orbital energies and enhances the current-contributing molecular density of states and the probabilities of resonance tunneling of conduction electrons from one electrode to another.

  11. The thermodynamics and transport properties of transition metals in critical point

    CERN Document Server

    Khomkin, Alexander L

    2016-01-01

    A new method for calculating the critical point parameters (density, temperature, pressure and electrical conductivity) and binodal of vapor-liquid (dielectric-metal) phase transition is proposed. It is based on the assumption that cohesion, which determines the main properties of solid state, also determines the properties in the vicinity of the critical point. Comparison with experimental and theoretical data available for transition metals is made.

  12. Volumetric and Transport Properties of Aqueous NaB(OH)4 Solutions

    Institute of Scientific and Technical Information of China (English)

    周永全; 房春晖; 房艳; 朱发岩

    2013-01-01

    Density, pH, viscosity, conductivity and the Raman spectra of aqueous NaB(OH)4 solutions precisely measured as functions of concentration at different temperatures (293.15, 298.15, 303.15, 313.15 and 323.15 K) are presented. Polyborate distributions in aqueous NaB(OH)4 solution were calculated, covering all the concentration range, 4B(OH)− is the most dominant species, other polyborate anions are less than 5.0%. The volumetric and the transport properties were discussed in detail, both of these properties indicate that 4B(OH)− behaves as a struc-ture-disordered anion.

  13. Effect of the molecular chain orientation on carrier transport and optical properties of polymer blends

    Science.gov (United States)

    Kažukauskas, V.; Čyras, V.; Pranaitis, M.; Apostoluk, A.; Rocha, L.; Sicot, L.; Raimond, P.; Sentein, C.

    2007-03-01

    We have investigated properties of poly(9-vinylcarbazole) (PVK) doped with 30% wt 4-dibutylamino-4'-nitrostilbene (DBANS), depending on the orientation of the polar DBANS molecules. Appearance of the orientation-induced built-in electrical field was proven optically by the Solid Electric Field Induced Second Harmonic Generation and electrically by Current-Voltage characterization. Modification of optical properties was evidenced by the spectral dependencies of absorption coefficient. The Thermally Stimulated Currents spectra demonstrated that carrier transport and trapping are affected, too. This paper has been presented at “ECHOS06”, Paris, 28 30 juin 2006.

  14. Strain Modulation of Electronic and Heat Transport Properties of Bilayer Boronitrene

    Science.gov (United States)

    Yang, Ming; Sun, Fang-Yuan; Wang, Rui-Ning; Zhang, Hang; Tang, Da-Wei

    2017-10-01

    Strain engineering has been proven as an effective approach to modify electronic and thermal properties of materials. Recently, strain effects on two-dimensional materials have become important relevant topics in this field. We performed density functional theory studies on the electronic and heat transport properties of bilayer boronitrene samples under an isotropic strain. We demonstrate that the strain will reduce the band gap width but keep the band gap type robust and direct. The strain will enhance the thermal conductivity of the system because of the increase in specific heat. The thermal conductivity was studied as a function of the phonon mean-free path.

  15. Transport properties of photonic topological insulators based on microring resonator array

    CERN Document Server

    Jiang, Xiaohui; Yin, Chenxuan; Zhang, Yanfeng; Chen, Hui; Yu, Siyuan

    2016-01-01

    An array of ring resonators specifically designed can perform as a topological insulator. We conduct simulations using both Tight-Binding Model (TBM) and Transfer Matrix Method (TMM) to analyze the transport properties of such optical structure, verifying the presence of robust topological edge states which is immune to disorder and defect. We have also made a comparison between these two methods, of which results suggesting that TBM is only applicable under weakly-coupling condition while TMM is more rigorous. Finally we compared the structure with common microring array and coupled resonator optical waveguide (CROW) to demonstrate that it has desired transmission properties with wide and flat spectral response.

  16. Structural, magnetic and transport properties of discontinuous granular multi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Denardin, J.C. [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas SP (Brazil); Knobel, M. [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas SP (Brazil)]. E-mail: knobel@ifi.unicamp.br; Dorneles, L.S. [Departamento de Fisica, CCNE, UFSM 97105-900, Santa Maria RS (Brazil); Schelp, L.F. [Departamento de Fisica, CCNE, UFSM 97105-900, Santa Maria RS (Brazil)

    2005-07-15

    Results of structural, magnetic and transport properties of magnetic Co/SiO{sub 2} discontinuous multi-layers produced by sequential deposition are presented. Transmission electron microscopy (TEM) images show that the samples that are close to metal-insulation transition are composed by a connected network of metallic paths, and display an enhanced Hall Effect. The granular samples are composed by an almost periodic array of Co nanoparticles, and after annealing these samples show a clear evolution in the nanostructure, with increasing average Co grain sizes and decreasing size dispersion. Relationships between the nanostructure and magnetotransport properties are discussed and compared with previous results obtained in cosputtered films.

  17. Properties of Martian winds as determined from trajectory modelling of jettisoned spacecraft parts

    Science.gov (United States)

    Paton, Mark; Harri, Ari-Matti; Savijärvi, Hannu

    2016-10-01

    Knowing the properties of the Martian winds, i.e. speed, direction and structure, is important for understanding the global circulation of the atmosphere, dust and water transport and planning the landing of spacecraft. Measurements of wind speed and direction on Mars have previously been limited to near-surface measurements made by landers, imaging of atmospheric features such as clouds and dust and while the lander is on the parachute. The understanding of the Martian environment could therefore benefit from more determinations of wind speed and direction.The distribution of spacecraft hardware, such as heat shields, parachutes, backshells and landers, on the surface of Mars have been imaged by the HiRISE imager on-board Mars Reconnaissance Orbiter. We analyse these images, and other known properties of a spacecraft's descent, to reconstruct the trajectories of the jettisoned spacecraft components and further constrain wind properties at various lander sites. Interestingly this approach may allow wind property assessments at the landing sites of failed landers assuming their hardware components can be correctly identified in images.We assess the vertical structure of the wind at selected landing sites of successful spacecraft missions to Mars by comparing our results to mesoscale (MLAM) and 1-D column models of the Martian atmosphere that have been jointly developed by FMI and the University of Helsinki. In addition we compare our wind property findings to published meteorological measurements and modelling. We discuss the implications of our results with respect to slope and crater circulations. The feasibility of imaging spacecraft hardware from orbit of the MetNet vehicle (metnet.fmi.fi) is assessed with space flight visualisation software.

  18. Anisotropic surface hole-transport property of triphenylamine-derivative single crystal prepared by solution method

    Science.gov (United States)

    Umeda, Minoru; Katagiri, Mitsuhiko; Shironita, Sayoko; Nagayama, Norio

    2016-12-01

    This paper reports the anisotropic hole transport at the triphenylamine-derivative single crystal surface prepared by a solution method. Triphenylamine derivatives are commonly used in a hole-transport material for organic photoconductors of laser-beam printers, in which the materials are used as an amorphous form. For developing organic photovoltaics using the photoconductor's technology, preparation of a single crystal seems to be a specific way by realizing the high mobility of an organic semiconductor. In this study, a single crystal of 4-(2,2-diphenylethenyl)-N,N-bis(4-methylphenyl)-benzenamine (TPA) was prepared and its anisotropic hole-transport property measured. First, the hole-transport property of the TPA was investigated based on its chemical structure and electrochemical redox characteristics. Next, a large-scale single crystal formation at a high rate was developed by employing a solution method based on its solubility and supersolubility curves. The grown TPA was found to be a single crystal based on the polarization micrograph observation and crystallographic analysis. For the TPA single crystal, an anisotropic surface conduction was found, which was well explained by its molecular stack structure. The measured current in the long-axis direction is one order of magnitude greater than that of amorphous TPA.

  19. Effect of Yield Power Law Fluid Rheological Properties on Cuttings Transport in Eccentric Horizontal Narrow Annulus

    Directory of Open Access Journals (Sweden)

    Titus Ntow Ofei

    2016-01-01

    Full Text Available Narrow annular drilling such as casing-while-drilling technique is gaining popularity due to its ability to mitigate nonproductive time during oil and gas drilling operations. However, very little is known about the flow dynamics in narrow annular drilling. In this study, the Eulerian-Eulerian two-fluid model was used to examine the influence of Yield Power Law fluid rheological properties on cuttings transport in eccentric horizontal narrow annulus. The flow was assumed as fully developed, laminar, and transient state. The present simulation model was validated against experimental data, where a mean percent error of −1.2% was recorded. Results revealed an increase in the radial distribution of cuttings transport velocity in the wide annular region as the consistency index, K, and the flow behavior index, n, increase. Nonetheless, increasing the yield stress, τo, had insignificant effect on the cuttings transport velocity. Three-dimensional profiles showed how cuttings preferred to travel in less resistant flow area, whereas cuttings concentration builds up in the narrow annular region. Furthermore, annular frictional pressure losses also increased as K, n, and τo increased. This study serves as a guide to properly optimize drilling fluid rheological properties for efficient cuttings transport and equivalent circulating density (ECD management in narrow annular drilling.

  20. The Influence of Calcium Chloride Salt Solution on the Transport Properties of Cementitious Materials

    Directory of Open Access Journals (Sweden)

    Yaghoob Farnam

    2015-01-01

    Full Text Available The chemical interaction between calcium chloride (CaCl2 and cementitious binder may alter the transport properties of concrete which are important in predicting the service life of infrastructure elements. This paper presents a series of fluid and gas transport measurements made on cementitious mortars before and after exposure to various solutions with concentrations ranging from 0% to 29.8% CaCl2 by mass. Fluid absorption, oxygen diffusivity, and oxygen permeability were measured on mortar samples prepared using Type I and Type V cements. Three primary factors influence the transport properties of mortar exposed to CaCl2: (1 changes in the degree of saturation, (2 calcium hydroxide leaching, and (3 formation of chemical reaction products (i.e., Friedel’s salt, Kuzel’s salt, and calcium oxychloride. It is shown that an increase in the degree of saturation decreases oxygen permeability. At lower concentrations (~12%, the formation of chemical reaction products (mainly calcium oxychloride is a dominant factor decreasing the fluid and gas transport in concrete.

  1. Modeling the Thermodynamic and Transport Properties of Decahydronaphthalene/Propane Mixtures: Phase Equilibria, Density, and Viscosity

    Science.gov (United States)

    2011-01-01

    Modeling the Thermodynamic and Transport Properties of Decahydronaphthalene/Propane Mixtures: Phase Equilibria , Density, and Viscosity Nathaniel...Decahydronaphthalene/Propane Mixtures: Phase Equilibria , Density, And Viscosity 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Keywords: phase equilibria ; modified Sanchez-Lacombe equation of state

  2. Size distribution and optical properties of African mineral dust after intercontinental transport

    Science.gov (United States)

    Denjean, Cyrielle; Formenti, Paola; Desboeufs, Karine; Chevaillier, Servanne; Triquet, Sylvain; Maillé, Michel; Cazaunau, Mathieu; Laurent, Benoit; Mayol-Bracero, Olga L.; Vallejo, Pamela; Quiñones, Mariana; Gutierrez-Molina, Ian E.; Cassola, Federico; Prati, Paolo; Andrews, Elisabeth; Ogren, John

    2016-06-01

    The transatlantic transport of mineral dust from Africa is a persistent atmospheric phenomenon, clue for understanding the impacts of dust at the global scale. As part of the DUST Aging and Transport from Africa to the Caribbean (Dust-ATTACk) intensive field campaign, the size distribution and optical properties of mineral dust were measured in June-July 2012 on the east coast of Puerto Rico, more than 5000 km from the west coast of Africa. During the recorded dust events, the PM10 (particulate matter 10 micrometers or less in diameter) concentrations increased from 20 to 70 µg m-3. Remote sensing observations and modeling analysis were used to identify the main source regions, which were found in the Western Sahara, Mauritania, Algeria, Niger, and Mali. The microphysical and optical properties of the dust plumes were almost independent of origin. The size distribution of mineral dust after long-range transport may have modal diameters similar to those on the eastern side of the Atlantic short time after emission, possibly depending on height of transport. Additional submicron particles of anthropogenic absorbing aerosols (likely from regional marine traffic activities) can be mixed within the dust plumes, without affecting in a significant way the PM10 absorption properties of dust observed in Puerto Rico. The Dust-ATTACk experimental data set may be useful for modeling the direct radiative effect of dust. For accurate representation of dust optical properties over the Atlantic remote marine region, we recommend mass extinction efficiency (MEE) and single-scattering albedo values in the range 1.1-1.5 m2 g-1 and 0.97-0.98, respectively, for visible wavelengths.

  3. Influence of Microstructure and Sintering Routes on Transport Properties of Apatite Materials for Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    A.Chesnaud; C.Estournes; G.Dezannau

    2007-01-01

    1 Results Oxy-apatite materials are thought as zirconia-substitutes in Solid Oxide Fuel Cells due to their fast ionic conduction. However, the well known difficulties related to their densification prevent them from being used as such. This study presents strategies to obtain oxy-apatite dense materials and the influence of elaboration route on transport properties. Particular emphasis is put on the microstructure effect on ion conduction. By the combined use of freeze-drying and conventional or spark p...

  4. Electronic properties of mesoscopic graphene structures: Charge confinement and control of spin and charge transport

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, A.V., E-mail: arozhkov@gmail.co [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412, Moscow (Russian Federation); Giavaras, G. [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Bliokh, Yury P. [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Freilikher, Valentin [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel); Nori, Franco [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2011-06-15

    This brief review discusses electronic properties of mesoscopic graphene-based structures. These allow controlling the confinement and transport of charge and spin; thus, they are of interest not only for fundamental research, but also for applications. The graphene-related topics covered here are: edges, nanoribbons, quantum dots, pn-junctions, pnp-structures, and quantum barriers and waveguides. This review is partly intended as a short introduction to graphene mesoscopics.

  5. Mass transport properties of Pu/DT mixtures from orbital free molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Kress, Joel David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ticknor, Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Collins, Lee A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-09-16

    Mass transport properties (shear viscosity and diffusion coefficients) for Pu/DT mixtures were calculated with Orbital Free Molecular Dynamics (OFMD). The results were fitted to simple functions of mass density (for ρ=10.4 to 62.4 g/cm3) and temperature (for T=100 up to 3,000 eV) for Pu/DT mixtures consisting of 100/0, 25/75, 50/50, and 75/25 by number.

  6. A computational study of the quantum transport properties of a Cu-CNT composite.

    Science.gov (United States)

    Ghorbani-Asl, Mahdi; Bristowe, Paul D; Koziol, Krzysztof

    2015-07-28

    The quantum transport properties of a Cu-CNT composite are studied using a non-equilibrium Green's function approach combined with the self-consistent-charge density-functional tight-binding method. The results show that the electrical conductance of the composite depends strongly on CNT density and alignment but more weakly on chirality. Alignment with the applied bias is preferred and the conductance of the composite increases as its mass density increases.

  7. The Determinants of Transportation Mode Choice in the Middle Eastern Cities: the Kerman Case, Iran

    Directory of Open Access Journals (Sweden)

    Hamid Soltanzadeh

    2014-07-01

    Full Text Available Having a precise understanding of the determinants of transportation mode choices and decisions can be under the influence of regional and cultural aspects. This paper outlines such determinants in the Iranian city of Kerman as a representative of the similar Middle Eastern cities located in hot-arid climates and Moslem cultures. The descriptive analysis of the results derived from a short survey that was a part of a larger study conducted in the second half of 2013 indicated that adding to accessibility to public transportation and the convenience of using it can persuade people to shift from car driving to public transit use. The main barriers to bicycling are socio-cultural aspects, while for walking the obstacles are physical and objective. Increasing the quality of pedestrian infrastructure and spaces is a stronger deterrent than personal attitudes against walking. Such findings show slight dissimilarities from the results of some of the western studies that find the built environment more effective. These findings can be a general guide for the Middle Eastern planners to promote walking, biking, and public transport use.

  8. Impact of lux gene insertion on bacterial surface properties and transport.

    Science.gov (United States)

    Chen, Gang; Srinivasa Ranga, Vijay Penagonda; Mao, Yongjun; Chen, Kevin; Qiao, Hanzi

    2008-03-01

    Genetic markers have been in popular use for tracing microbial movement in the environment. However, the impact of genetic marker insertion on microbial surface properties and consequent transport is often ignored. For this research, we investigated the impact of luminescence-based genetic marker insertion on bacterial surface properties and transport. Typical Gram-positive bacterial strains of Lactobacillus casei, Streptococcus mitis and Micrococcus luteus were used as model bacterial strains in this research. We manipulated gene transfer to observe the impact of lux gene insertion on bacterial surface properties based on contact angle measurements, and we conducted column experiments to evaluate the impact of lux gene insertion on bacterial transport. After lux gene insertion, bacterial interactions with the porous media increased, demonstrating stronger deposition potential in the porous media. Accordingly, retention of the daughter strains increased. Lux gene insertion also resulted in an increase in bacterial dispersion and equilibrium adsorption in the porous media. The bacterial deposition coefficient was found to correlate with the free energy of interactions between bacteria and the porous media.

  9. Transport properties of the topological Kondo insulator SmB6 under the irradiation of light

    Science.gov (United States)

    Zhu, Guo-Bao; Yang, Hui-Min

    2016-10-01

    In this paper, we study transport properties of the X point in the Brillouin zone of the topological Kondo insulator SmB6 under the application of a circularly polarized light. The transport properties at high-frequency regime and low-frequency regime as a function of the ratio (κ) of the Dresselhaus-like and Rashba-like spin-orbit parameter are studied based on the Floquet theory and Boltzmann equation respectively. The sign of Hall conductivity at high-frequency regime can be reversed by the ratio κ and the amplitude of the light. The amplitude of the current can be enhanced by the ratio κ. Our findings provide a way to control the transport properties of the Dirac materials at low-frequency regime. Project supported by the National Natural Science Foundation of China (Grant Nos. 11504095 and 11447145), the Foundation of Heze University (Grant Nos. XY14B002 and XYPY01), and the Project funded by the Higher Educational Science and Technology Program of Shandong Province, China (Grant No. J15LJ55).

  10. Formulating gels for decreased mucociliary transport using rheologic properties: polyacrylic acids.

    Science.gov (United States)

    Shah, Ankur J; Donovan, Maureen D

    2007-04-20

    The purpose of these studies was to identify the rheologic properties of polyacrylic acid gels necessary for optimal reductions in mucociliary clearance. The mucociliary transport of 2 bioadhesive polyacrylic acid polymers, polycarbophil and carbopol, was assessed in vitro by measuring their clearance rates across explants of ciliated bovine tracheal tissue. The viscoelastic properties of polymer gels were measured in the presence of mucus using controlled stress rheometry. Combinations of apparent viscosity (eta) and complex modulus (G*) were found to be the most useful parameters in the identification of polyacrylic acid formulations capable of decreasing mucociliary transport rate (MTR). A narrow range of eta and G* values suitable for reducing mucociliary clearance, while remaining sufficiently fluid for intranasal administration, were identified. The correlations between the rheologic parameters of the polycarbophil gels and their mucociliary transport rates were used to identify other polyacrylic acid gels that also had suitable mucociliary clearance properties, demonstrating that these parameters can be used to direct the optimization of formulations using simple in vitro rheologic testing.

  11. Calculation of effective transport properties of partially saturated gas diffusion layers

    Science.gov (United States)

    Bednarek, Tomasz; Tsotridis, Georgios

    2017-02-01

    A large number of currently available Computational Fluid Dynamics numerical models of Polymer Electrolyte Membrane Fuel Cells (PEMFC) are based on the assumption that porous structures are mainly considered as thin and homogenous layers, hence the mass transport equations in structures such as Gas Diffusion Layers (GDL) are usually modelled according to the Darcy assumptions. Application of homogenous models implies that the effects of porous structures are taken into consideration via the effective transport properties of porosity, tortuosity, permeability (or flow resistance), diffusivity, electric and thermal conductivity. Therefore, reliable values of those effective properties of GDL play a significant role for PEMFC modelling when employing Computational Fluid Dynamics, since these parameters are required as input values for performing the numerical calculations. The objective of the current study is to calculate the effective transport properties of GDL, namely gas permeability, diffusivity and thermal conductivity, as a function of liquid water saturation by using the Lattice-Boltzmann approach. The study proposes a method of uniform water impregnation of the GDL based on the "Fine-Mist" assumption by taking into account the surface tension of water droplets and the actual shape of GDL pores.

  12. Comparison of transport properties models for numerical simulations of Mars entry vehicles

    Science.gov (United States)

    Hao, Jiaao; Wang, Jingying; Gao, Zhenxun; Jiang, Chongwen; Lee, Chunhian

    2017-01-01

    Effects of two different models for transport properties, including the approximate model and the collision integral model, on hypersonic flow simulations of Mars entry vehicles are numerically investigated. A least square fitting is firstly performed using the best-available data of collision integrals for Martian atmosphere species within the temperature range of 300-20,000 K. Then, the performance of these two transport properties models are compared for an equilibrium Martian atmosphere gas mixture at 10 kPa and temperatures ranging from 1000 to 10,000 K. Finally, four flight conditions chosen from the trajectory of the Mars Pathfinder entry vehicle are numerically simulated. It is indicated that the approximate model is capable of accurately providing the distributions of species mass fractions and temperatures in the flowfield. Both models give similar translational-rotational and vibrational heat fluxes. However, the chemical diffusion heat fluxes predicted by the approximate model are significantly larger than the results computed by the collision integral model, particularly in the vicinity of the forebody stagnation point, whose maximum relative error of 15% for the super-catalytic case. The diffusion model employed in the approximate model is responsible to the discrepancy. In addition, the wake structure is largely unaffected by the transport properties models.

  13. Dispersion stability and electrokinetic properties of intrinsic plutonium colloids: implications for subsurface transport.

    Science.gov (United States)

    Abdel-Fattah, Amr I; Zhou, Dongxu; Boukhalfa, Hakim; Tarimala, Sowmitri; Ware, S Doug; Keller, Arturo A

    2013-06-04

    Subsurface transport of plutonium (Pu) may be facilitated by the formation of intrinsic Pu colloids. While this colloid-facilitated transport is largely governed by the electrokinetic properties and dispersion stability (resistance to aggregation) of the colloids, reported experimental data is scarce. Here, we quantify the dependence of ζ-potential of intrinsic Pu(IV) colloids on pH and their aggregation rate on ionic strength. Results indicate an isoelectric point of pH 8.6 and a critical coagulation concentration of 0.1 M of 1:1 electrolyte at pH 11.4. The ζ-potential/pH dependence of the Pu(IV) colloids is similar to that of goethite and hematite colloids. Colloid interaction energy calculations using these values reveal an effective Hamaker constant of the intrinsic Pu(IV) colloids in water of 1.85 × 10(-19) J, corresponding to a relative permittivity of 6.21 and refractive index of 2.33, in agreement with first principles calculations. This relatively high Hamaker constant combined with the positive charge of Pu(IV) colloids under typical groundwater aquifer conditions led to two contradicting hypotheses: (a) the Pu(IV) colloids will exhibit significant aggregation and deposition, leading to a negligible subsurface transport or (b) the Pu(IV) colloids will associate with the relatively stable native groundwater colloids, leading to a considerable subsurface transport. Packed column transport experiments supported the second hypothesis.

  14. Blue emitting 1,8-naphthalimides with electron transport properties for organic light emitting diode applications

    Science.gov (United States)

    Ulla, Hidayath; Kiran, M. Raveendra; Garudachari, B.; Ahipa, T. N.; Tarafder, Kartick; Adhikari, Airody Vasudeva; Umesh, G.; Satyanarayan, M. N.

    2017-09-01

    In this article, the synthesis, characterization and use of two novel naphthalimides as electron-transporting emitter materials for organic light emitting diode (OLED) applications are reported. The molecules were obtained by substituting electron donating chloro-phenoxy group at the C-4 position. A detailed optical, thermal, electrochemical and related properties were systematically studied. Furthermore, theoretical calculations (DFT) were performed to get a better understanding of the electronic structures. The synthesized molecules were used as electron transporters and emitters in OLEDs with three different device configurations. The devices with the molecules showed blue emission with efficiencies of 1.89 cdA-1, 0.98 lmW-1, 0.71% at 100 cdm-2. The phosphorescent devices with naphthalimides as electron transport materials displayed better performance in comparison to the device without any electron transporting material and were analogous with the device using standard electron transporting material, Alq3. The results demonstrate that the naphthalimides could play a significant part in the progress of OLEDs.

  15. Transport proteins determine drug sensitivity and resistance in a protozoan parasite, Trypanosoma brucei

    Science.gov (United States)

    Munday, Jane C.; Settimo, Luca; de Koning, Harry P.

    2015-01-01

    Drug resistance in pathogenic protozoa is very often caused by changes to the ‘transportome’ of the parasites. In Trypanosoma brucei, several transporters have been implicated in uptake of the main classes of drugs, diamidines and melaminophenyl arsenicals. The resistance mechanism had been thought to be due to loss of a transporter known to carry both types of agents: the aminopurine transporter P2, encoded by the gene TbAT1. However, although loss of P2 activity is well-documented as the cause of resistance to the veterinary diamidine diminazene aceturate (DA; Berenil®), cross-resistance between the human-use arsenical melarsoprol and the diamidine pentamidine (melarsoprol/pentamidine cross resistance, MPXR) is the result of loss of a separate high affinity pentamidine transporter (HAPT1). A genome-wide RNAi library screen for resistance to pentamidine, published in 2012, gave the key to the genetic identity of HAPT1 by linking the phenomenon to a locus that contains the closely related T. brucei aquaglyceroporin genes TbAQP2 and TbAQP3. Further analysis determined that knockdown of only one pore, TbAQP2, produced the MPXR phenotype. TbAQP2 is an unconventional aquaglyceroporin with unique residues in the “selectivity region” of the pore, and it was found that in several MPXR lab strains the WT gene was either absent or replaced by a chimeric protein, recombined with parts of TbAQP3. Importantly, wild-type AQP2 was also absent in field isolates of T. b. gambiense, correlating with the outcome of melarsoprol treatment. Expression of a wild-type copy of TbAQP2 in even the most resistant strain completely reversed MPXR and re-introduced HAPT1 function and transport kinetics. Expression of TbAQP2 in Leishmania mexicana introduced a pentamidine transport activity indistinguishable from HAPT1. Although TbAQP2 has been shown to function as a classical aquaglyceroporin it is now clear that it is also a high affinity drug transporter, HAPT1. We discuss here a

  16. Transport proteins determine drug sensitivity and resistance in a protozoan parasite, Trypanosoma brucei

    Directory of Open Access Journals (Sweden)

    Jane Claire Munday

    2015-03-01

    Full Text Available Drug resistance in pathogenic protozoa is very often caused by changes to the ‘transportome’ of the parasites. In Trypanosoma brucei, several transporters have been implicated in uptake of the main classes of drugs, diamidines and melaminophenyl arsenicals. The resistance mechanism had been thought to be due to loss of a transporter known to carry both types of agents: the aminopurine transporter P2, encoded by the gene TbAT1. However, although loss of P2 activity is well-documented as the cause of resistance to the veterinary diamidine diminazene aceturate (Berenil®, cross-resistance between the human-use arsenical melarsoprol and the diamidine pentamidine (MPXR is the result of loss of a separate High Affinity Pentamidine Transporter (HAPT1. A genome-wide RNAi library screen for resistance to pentamidine, published in 2012, gave the key to the genetic identity of HAPT1 by linking the phenomenon to a locus that contains the closely related T. brucei aquaglyceroporin genes TbAQP2 and TbAQP3. Further analysis determined that knockdown of only one pore, TbAQP2, produced the MPXR phenotype. TbAQP2 is an unconventional aquaglyceroporin with unique residues in the selectivity region of the pore, and it was found that in several MPXR lab strains the WT gene was either absent or replaced by a chimeric protein, recombined with parts of TbAQP3. Importantly, wild-type AQP2 was also absent in field isolates of T. b. gambiense, correlating with the outcome of melarsoprol treatment. Expression of a wild-type copy of TbAQP2 in even the most resistant strain completely reversed MPXR and re-introduced HAPT1 function and transport kinetics. Expression of TbAQP2 in Leishmania mexicana introduced a pentamidine transport activity indistinguishable from HAPT1. Although TbAQP2 has been shown to function as a classical aquaglyceroporin it is now clear that it is also a high affinity drug transporter, HAPT1. We discuss here a possible structural rationale for this

  17. Characterisation of advanced windows. Determination of thermal properties by measurements

    Energy Technology Data Exchange (ETDEWEB)

    Duer, K.

    2001-04-01

    optically inhomogeneous materials). Therefor an outdoor test facility has been constructed in order to facilitate the measurement of direct solar transmittance of optically inhomogeneous samples under natural solar radiation and under any chosen angle of incidence. The test facility is based on a scanning pyranometer mounted in a tracking device. Utilising the equipment and the procedures for measurements and data treatment described in this report will in most cases allow a full thermal characterisation of advanced windows and glazings to be carried out by measurements and with good accuracy. As an example of this the thermal and optical properties of a prototypical aerogel glazing have been determined by means of measurements. (au)

  18. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    Directory of Open Access Journals (Sweden)

    C. Denjean

    2015-08-01

    Full Text Available This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June–July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco, time of tranport (1–5 days and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried higher concentration of pollution particles at intermediate altitude (1–3 km than at elevated altitude (> 3 km, resulting in scattering Angstrom exponent up to 2.2 within the intermediate altitude. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate light absorption of the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00 ± 0.04. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assimilated to those of native dust in radiative transfer simulations

  19. Determination of Weight Suspension Rigidity in the Transport-Erector Aggregates

    Directory of Open Access Journals (Sweden)

    V. A. Zverev

    2016-01-01

    Full Text Available The aim is to determine weight suspension rigidity in aggregates designed to perform technological transport-erector operations at the miscellaneous launch complexes.We consider the weight suspension comprising the following distinctive structural components: the executive weight-lowering mechanism, polyspast mechanism, rope, traverse, and rods. A created structural dynamic model of suspension allowed us to define weight suspension rigidity. Within the framework of design analysis of a dynamic model we determined the rigidity of its structural units, i.e. traverse, rope, and polyspast.Known analytical relationships were used to calculate the rope rigidity. To determine rigidity of polyspast and traverse have been created special models based on the finite element method. For each model deformation in the specific points under the test load have been defined. Data obtained were used to determine trigidity of traverses and polyspast, and also rigidity of suspension in total. The rigidity models of polispast mechanism and traverse have been developed and calculated using the software complex "Zenit-95".As the research results, the paper presents a dynamic model of the weight suspension of the transport-erector aggregate, the finite element models of the polispast mechanism and traverse, an algorithm for determining the weight suspension rigidity and relevant analytical relationships.Independent calculation of weight suspension rigidity enables us to simplify further dynamic calculation of the aggregate-weight system because it allows attaining a simpler model of the aggregate-weight system that uses the weight suspension model as an element of equivalent rigidity. Despite this simplification the model allows us to determine correctly weight movement parameters and overloads in the aggregate-weight system in the process of technical operations.

  20. Representative equations for the thermodynamic and transport properties of fluids near the gas-liquid critical point

    Science.gov (United States)

    Sengers, J. V.; Basu, R. S.; Sengers, J. M. H. L.

    1981-01-01

    A survey is presented of representative equations for various thermophysical properties of fluids in the critical region. Representative equations for the transport properties are included. Semi-empirical modifications of the theoretically predicted asymtotic critical behavior that yield simple and practical representations of the fluid properties in the critical region are emphasized.

  1. Microstructure, magnetic and transport properties of magnetoresistive Cu{sub 80}Fe{sub x}Ni{sub 20-x} (x = 5, 10 and 15 at.%) ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Cazottes, S.; Fnidiki, A., E-mail: abdeslem.fnidiki@univ-rouen.fr [Site Universitaire du Madrillet, Groupe de Physique des Materiaux, UMR CNRS 6634 (France); Coisson, M. [INRIM, Electromagnetism Division (Italy); Lemarchand, D.; Danoix, F. [Site Universitaire du Madrillet, Groupe de Physique des Materiaux, UMR CNRS 6634 (France); Ochin, P. [Institut de Chimie et des Materiaux Paris Est (ex CECM), UMR 7182 CNRS (France)

    2012-07-15

    Microstructure, magnetic and transport properties of magnetoresistive Cu{sub 80}Fe{sub x}Ni{sub 20-x} (x = 5, 10 and 15 at.%) melt-spun ribbons were studied for the as-spun and annealed for 2 h at 400 to 600 Degree-Sign C samples. The microstructure was characterised by means of X-ray diffraction, transmission electron microscopy, energy filtered transmission electron microscopy and Moessbauer spectrometry (MS). Magnetic and transport measurements such as magnetization, zero field cooled/field cooled and giant magnetoresistance (GMR) measurements at 5 and 300 K were performed. The aim of this work is to study the influence of the microstructure of as-spun and annealed ribbons on magnetic and transport properties at 5 and 300 K. We have precisely determined the nature of precipitation of nanoparticles, the relative proportion and the magnetic properties of each phase in such a system using MS at both temperatures. We report the conclusive observation of the magnetic behaviour of each phase which was correlated to the structural data to explain the GMR properties that are observed. The influence of magnetic interactions between nanoparticles on magnetic and magnetoresistive properties of these ribbons was determined. We have clearly shown the existence and the nature of the magnetic interactions that reduce the GMR.

  2. The effects of surface functionalization on rheology, structure and transport properties of nanocomposites

    Science.gov (United States)

    Ranka, Moulik A.

    In this thesis, the effects of surface functionalization using hydrophobic silanes on properties of nanocomposites comprising 42 nm silica particles suspended in a melt of polyethylene-glycol (PEG) are studied using rheological, static and dynamic x-ray scattering studies. The nanocomposites are studied in the low molecular weight unentangled (PEG-400) and high molecular weight entangled (PEG-20000) regimes. We find no differences in the properties of the bare and silanized particles in the low volume fraction regime up to where the interparticle separation distance h > 6Rg. In the region of 6Rg > h > 3Rg (5Rg > h > 3Rg, in case of entangled melts), we find substantial differences in the rheological, structure and transport properties when comparing the bare and silanized particles. In the unentangled melts, we observe up to four orders of magnitude drop in the viscosity of the composites at the highest levels of silanization and observe shear thinning behavior that is unlike what is universally seen for hard spheres. For the entangled melts, a yield stress is observed for the silanized particles that is absent in the case of the bare particles and there is a divergence in the elastic modulus in comparison to bare particles. We observe an anomalous speed up in the density relaxations and an associated maxima in structure properties in the case of unentangled melts which has been reported previously for particles experiencing soft repulsive potentials. A clear reentrant behavior in structure and transport properties is observed for bare particles in the entangled melts that have been previously reported for particles interacting with soft repulsive potentials such as square shoulder and ramp potentials. In the silanized systems, the density relaxation times although lower than bare particles, is ii unaffected by increasing volume fraction up to h ~ 3Rg and is decoupled from the structure properties which are non-monotonic similar to bare particles. In the region of

  3. Constitutive Relations for Reactive Transport Modeling: Effects of Chemical Reactions on Multi-Phase Flow Properties

    Science.gov (United States)

    Zhang, S.; Liu, H. H.; van Dijke, M. I.; Geiger, S.; Agar, S. M.

    2016-12-01

    The relationship between flow properties and chemical reactions is key to modeling subsurface reactive transport. This study develops closed-form equations to describe the effects of mineral precipitation and dissolution on multiphase flow properties (capillary pressure and relative permeabilities) of porous media. The model accounts for the fact that precipitation/dissolution only takes place in the water-filled part of pore space. The capillary tube concept was used to connect pore-scale changes to macroscopic hydraulic properties. Precipitation/dissolution induces changes in the pore radii of water-filled pores and consequently in the pore-size distribution. The updated pore-size distribution is converted back to a new capillary pressure-water saturation relation from which the new relative permeabilities are calculated. Pore network modeling is conducted on a Berea sandstone to validate the new continuum-scale relations. The pore network modeling results are satisfactorily predicted by the new closed-form equations. Currently the effects of chemical reactions on flow properties are represented as a relation between permeability and porosity in reactive transport modeling. Porosity is updated after chemical calculations from the change of mineral volumes, then permeability change is calculated from the porosity change using an empirical permeability-porosity relation, most commonly the Carman-Kozeny relation, or the Verma-Pruess relation. To the best of our knowledge, there are no closed-form relations available yet for the effects of chemical reactions on multi-phase flow properties, and thus currently these effects cannot be accounted for in reactive transport modeling. This work presents new constitutive relations to represent how chemical reactions affect multi-phase flow properties on the continuum scale based on the conceptual model of parallel capillary tubes. The parameters in our new relations are either pre-existing input in a multi-phase flow

  4. Direct optical determination of interfacial transport barriers in molecular tunnel junctions.

    Science.gov (United States)

    Fereiro, Jerry A; McCreery, Richard L; Bergren, Adam Johan

    2013-07-03

    Molecular electronics seeks to build circuitry using organic components with at least one dimension in the nanoscale domain. Progress in the field has been inhibited by the difficulty in determining the energy levels of molecules after being perturbed by interactions with the conducting contacts. We measured the photocurrent spectra for large-area aliphatic and aromatic molecular tunnel junctions with partially transparent copper top contacts. Where no molecular absorption takes place, the photocurrent is dominated by internal photoemission, which exhibits energy thresholds corresponding to interfacial transport barriers, enabling their direct measurement in a functioning junction.

  5. Determination of Heat Transport Mechanism in Aqueous Nanofluids Using Regime Diagram

    Institute of Scientific and Technical Information of China (English)

    M.CHANDRASEKAR; S.SURESH

    2009-01-01

    We provide an approximate method to determine the dominant heat transport mechanism responsible for the anomalous enhancement of thermal conductivity in aqueous nanofluids.Due to a large degree of randomness and scatter observed in the published experimental data,limits to nanofluid thermal conductivity are fixed analytically by taking into account the contribution of particle Brownian motion and clustering,and a regime diagram is developed.Experimental data from a range of independent published sources is used for validation of the developed regime diagram.

  6. Large eddy simulation of turbulent statistical and transport properties in stably stratified flows

    Institute of Scientific and Technical Information of China (English)

    Xiang QIU; Yong-xiang HUANG; Zhi-ming LU; Yu-lu LIU

    2009-01-01

    Three dimensional large eddy simulation (LES) is performed in the inves-tigation of stably stratified turbulence with a sharp thermal interface. Main results are focused on the turbulent characteristic scale, statistical properties, transport properties,and temporal and spatial evolution of the scalar field. Results show that the buoyancy scale increases first, and then goes to a certain constant value. The stronger the mean shear, the larger the buoyancy scale. The overturning scale increases with the flow, and the mean shear improves the overturning scale. The flatness factor of temperature de-parts from the Ganssian distribution in a fairly large region, and its statistical properties are clearly different from those of the velocity fluctuations in strong stratified cases. Tur-bulent mixing starts from small scale motions, and then extends to large scale motions.

  7. determination of personal and common property during dissolution ...

    African Journals Online (AJOL)

    613/93, Federal Supreme Court Case Report, Vol. 1, Addis Ababa ..... In short, the courts' inquiry for a written evidence registered with a court has no legal ... underpinning business partnership with the purpose behind marital property. Despite ...

  8. Properties of theranostic nanoparticles determined in suspension by ultrasonic spectroscopy.

    Science.gov (United States)

    Astafyeva, Ksenia; Thomas, Jean-Louis; Coulouvrat, François; Guédra, Matthieu; Diou, Odile; Mousnier, Ludivine; Tsapis, Nicolas; Urbach, Wladimir; Taulier, Nicolas

    2015-10-14

    In the context of growing use of nanoparticles, it is important to be able to characterize all their physical properties in order to understand their behavior, to optimize them, and to control their quality. We showed that ultrasonic spectroscopy provides many of the desired properties. To do so, we used as an example nanocapsules made of a polymer shell encaspulating a liquid perfluorocarbon core and designed them for theranostic applications. Frequency-dependent measurements of both ultrasound velocity and attenuation were performed on nanocapsule suspensions. Then the desired properties were extracted by analyzing the experimental data using a recently developed model that relates the speed of sound and attenuation of a suspension to the geometrical and viscoelastic properties of the nanocapsules.

  9. Thermodynamic properties and transport coefficients of air thermal plasmas mixed with ablated vapors of Cu and polytetrafluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, JunMin, E-mail: jmzhang@buaa.edu.cn, E-mail: guanyg@tsinghua.edu.cn; Lu, ChunRong [School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191 (China); Guan, YongGang, E-mail: jmzhang@buaa.edu.cn, E-mail: guanyg@tsinghua.edu.cn; Liu, WeiDong [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China)

    2015-10-15

    Because the fault arc in aircraft electrical system often causes a fire, it is particularly important to analyze its energy and transfer for aircraft safety. The calculation of arc energy requires the basic parameters of the arc. This paper is mainly devoted to the calculations of equilibrium composition, thermodynamic properties (density, molar weight, enthalpy, and specific heat at constant pressure) and transport coefficients (thermal conductivity, electrical conductivity, and viscosity) of plasmas produced by a mixture of air, Cu, and polytetrafluoroethylene under the condition of local thermodynamic equilibrium. The equilibrium composition is determined by solving a system of equations around the number densities of each species. The thermodynamic properties are obtained according to the standard thermodynamic relationships. The transport coefficients are calculated using the Chapman-Enskog approximations. Results are presented in the temperature range from 3000 to 30 000 K for pressures of 0.08 and 0.1 MPa, respectively. The results are more accurate and are reliable reference data for theoretical analysis and computational simulation of the behavior of fault arc.

  10. A Darwinian view of metabolism: molecular properties determine fitness.

    Science.gov (United States)

    Firn, Richard D; Jones, Clive G

    2009-01-01

    Why do organisms make the types of chemicals that they do? Evolutionary theory tells us that individuals within populations will be subject to mutation and that some of those mutations will be enzyme variants that make new chemicals. A mutant making a novel chemical for that species will only survive in the population if the 'cost' of making the new chemical is outweighed by the benefits that result from making that molecule. The benefits, or adverse consequences, that a novel chemical X can confer to the individual organism are not a property of the simple existence of X in the cell but can be traced to one of the multiple properties that X will possess because of its molecular structure. By considering only three basic types of molecular property and by considering how selection pressures will differ for each kind of property, it is possible to account for much of the chemical diversity made by organisms. Such an evolutionary model can also explain why the properties of enzymes will differ depending on the molecular properties of the chemicals they make, and why the widely accepted terms 'primary metabolism' and 'secondary metabolism' have been so misleading and unsatisfactory.

  11. Strain-modulated electronic and thermal transport properties of two-dimensional O-silica

    Science.gov (United States)

    Han, Yang; Qin, Guangzhao; Jungemann, Christoph; Hu, Ming

    2016-07-01

    Silica is one of the most abundant materials in the Earth’s crust and is a remarkably versatile and important engineering material in various modern science and technology. Recently, freestanding and well-ordered two-dimensional (2D) silica monolayers with octahedral (O-silica) building blocks were found to be theoretically stable by (Wang G et al 2015 J. Phys. Chem. C 119 15654-60). In this paper, by performing first-principles calculations, we systematically investigated the electronic and thermal transport properties of 2D O-silica and also studied how these properties can be tuned by simple mechanical stretching. Unstrained 2D O-silica is an insulator with an indirect band gap of 6.536 eV. The band gap decreases considerably with bilateral strain up to 29%, at which point a semiconductor-metal transition occurs. More importantly, the in-plane thermal conductivity of freestanding 2D O-silica is found to be unusually high, which is around 40 to 50 times higher than that of bulk α-quartz and more than two orders of magnitude higher than that of amorphous silica. The thermal conductivity of O-silica decreases by almost two orders of magnitude when the bilateral stretching strain reaches 10%. By analyzing the mode-dependent phonon properties and phonon-scattering channel, the phonon lifetime is found to be the dominant factor that leads to the dramatic decrease of the lattice thermal conductivity under strain. The very sensitive response of both band gap and phonon transport properties to the external mechanical strain will enable 2D O-silica to easily adapt to the different environment of realistic applications. Our study is expected to stimulate experimental exploration of further physical and chemical properties of 2D silica systems, and offers perspectives on modulating the electronic and thermal properties of related low-dimensional structures for applications such as thermoelectric, photovoltaic, and optoelectronic devices.

  12. GaAs nanowires: from manipulation of defect formation to controllable electronic transport properties.

    Science.gov (United States)

    Han, Ning; Hou, Jared J; Wang, Fengyun; Yip, SenPo; Yen, Yu-Ting; Yang, Zai-Xing; Dong, Guofa; Hung, TakFu; Chueh, Yu-Lun; Ho, Johnny C

    2013-10-22

    Reliable control in the crystal quality of synthesized III-V nanowires (NWs) is particularly important to manipulate their corresponding electronic transport properties for technological applications. In this report, a "two-step" growth process is adopted to achieve single-crystalline GaAs NWs, where an initial high-temperature nucleation process is employed to ensure the formation of high Ga supersaturated Au7Ga3 and Au2Ga alloy seeds, instead of the low Ga supersaturated Au7Ga2 seeds observed in the conventional "single-step" growth. These two-step NWs are long (>60 μm) and thick (>80 nm) with the minimal defect concentrations and uniform growth orientations. Importantly, these NWs exhibit p-type conductivity as compared to the single-step grown n-type NWs for the same diameter range. This NW conductivity difference (p- versus n-channel) is shown to originate from the donor-like crystal defects, such as As precipitates, induced by the low Ga supersaturated multicrystalline Au7Ga2 alloy seeds. Then the well-controlled crystal quality for desired electronic properties is further explored in the application of large-scale p-type GaAs NW parallel array FETs as well as the integration of both p- and n-type GaAs NWs into CMOS inverters. All these illustrate the successful control of NW crystal defects and corresponding electronic transport properties via the manipulation of Ga supersaturation in the catalytic alloy tips with different preparation methods. The understanding of this relationship between NW crystal quality and electronic transport properties is critical and preferential to the future development of nanoelectronic materials, circuit design, and fabrication.

  13. Using Contaminant Transport Modeling to Determine Historical Discharges at the Surface

    Science.gov (United States)

    Fogwell, T. W.

    2013-12-01

    When it is determined that a contaminated site needs to be remediated, the issue of who is going to pay for that remediation is an immediate concern. This means that there needs to be a determination of who the responsible parties are for the existing contamination. Seldom is it the case that records have been made and kept of the surface contaminant discharges. In many cases it is possible to determine the relative amount of contaminant discharge at the surface of the various responsible parties by employing a careful analysis of the history of contaminant transport through the surface, through the vadose zone, and within the saturated zone. The process begins with the development of a dynamic conceptual site model that takes into account the important features of the transport of the contaminants through the vadose zone and in the groundwater. The parameters for this model can be derived from flow data available for the site. The resulting contaminant transport model is a composite of the vadose zone transport model, together with the saturated zone (groundwater) flow model. Any calibration of the model should be carefully employed in order to avoid using information about the conclusions of the relative discharge amounts of the responsible parties in determining the calibrated parameters. Determination of the leading edge of the plume is an important first step. It is associated with the first discharges from the surface of the site. If there were several discharging parties at the same time, then it is important to establish a chemical or isotopic signature of the chemicals that were discharged. The time duration of the first discharger needs to be determined as accurately as possible in order to establish the appropriate characterization of the leading portion of the resulting plume in the groundwater. The information about the first discharger and the resulting part of the plume associated with this discharger serves as a basis for the determination of the

  14. Theory of Band Warping and its Effects on Thermoelectronic Transport Properties

    Science.gov (United States)

    Mecholsky, Nicholas; Resca, Lorenzo; Pegg, Ian; Fornari, Marco

    2015-03-01

    Transport properties of materials depend upon features of band structures near extrema in the BZ. Such features are generally described in terms of quadratic expansions and effective masses. Such expansions, however, are permissible only under strict conditions that are sometimes violated by materials. Suggestive terms such as ``band warping'' have been used to refer to such situations and ad hoc methods have been developed to treat them. We develop a generally applicable theory, based on radial expansions, and a corresponding definition of angular effective mass which also accounts for effects of band non-parabolicity and anisotropy. Further, we develop precise procedures to evaluate band warping quantitatively and as an example we analyze the warping features of valence bands in silicon using first-principles calculations and we compare those with semi-empirical models. We use our theory to generalize derivations of transport coefficients for cases of either single or multiple electronic bands, with either quadratically expansible or warped energy surfaces. We introduce the transport-equivalent ellipsoid and illustrate the drastic effects that band warping can induce on thermoelectric properties using multi-band models. Vitreous State Laboratory and Samsung's GRO program.

  15. Electrical Transport Properties of Mn doped Bi2Se3 Thin Films

    Science.gov (United States)

    Babakiray, Sercan; Johnson, Trent; Borisov, Pavel; Lederman, David

    2015-03-01

    Magnetic impurity doping in topological insulators manifest itself with a gap opening in the Dirac cone as a result of breaking the time reversal symmetry. Moreover, the magnetic impurities affect the structural and quantum transport properties of topological insulators by increasing the disorder and by changing the bulk charge carrier type, charge carrier density and Hall mobility. Here, we investigated the effect of Mn doping on the structural and electrical transport properties of Bi2-xMnxSe3 thin films which are 12 quintuple layers thick and grown on Al2O3 (0001) single crystal substrates via molecular beam epitaxy (MBE). Hikami-Larkin-Nagaoka (HLN) formalism was used to study the weak antilocalization (WAL). Increasing Mn doping concentration was found to increase the bulk charge carrier density and to decrease the Hall mobility. A decrease was also observed in the phase coherence length related to WAL as a function of Mn content x. Values of another WAL parameter, the pre-factor alpha, showed that the top and bottom surfaces were coupled through the bulk conducting channels. The temperature dependence of phase coherence length indicated the electrical transport was dominated by 2D electron-electron scattering for the undoped, and by bulk weak localization effects for the Mn doped samples, respectively.

  16. Literature Survey of Crude Oil Properties Relevant to Handling and Fire Safety in Transport.

    Energy Technology Data Exchange (ETDEWEB)

    Lord, David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Luketa, Anay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wocken, Chad [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schlasner, Steve [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aulich, Ted [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Allen, Ray [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rudeen, David Keith [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Several fiery rail accidents in 2013-2015 in the U.S. and Canada carrying crude oil produced from the Bakken region of North Dakota have raised questions at many levels on the safety of transporting this, and other types of crude oil, by rail. Sandia National Laboratories was commissioned by the U.S. Department of Energy to investigate the material properties of crude oils, and in particular the so-called "tight oils" like Bakken that comprise the majority of crude oil rail shipments in the U.S. at the current time. The current report is a literature survey of public sources of information on crude oil properties that have some bearing on the likelihood or severity of combustion events that may occur around spills associated with rail transport. The report also contains background information including a review of the notional "tight oil" field operating environment, as well a basic description of crude oils and potential combustion events in rail transport. This page intentionally blank

  17. Effects of functional group mass variance on vibrational properties and thermal transport in graphene

    Science.gov (United States)

    Lindsay, L.; Kuang, Y.

    2017-03-01

    Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. Here we present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first-principles calculations. We use graphane, a buckled graphene backbone with covalently bonded hydrogen atoms on both sides, as the base material and vary the mass of the hydrogen atoms to simulate the effect of mass variance from other functional groups. We find nonmonotonic behavior of κ with increasing mass of the functional group and an unusual crossover from acoustic-dominated to optic-dominated thermal transport behavior. We connect this crossover to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection-symmetry-based scattering selection rule responsible for their large contributions in graphene. This work demonstrates the potential for manipulation and engineering of thermal transport properties in two-dimensional materials toward targeted applications.

  18. Investigation of chemical properties and transport phenomena associated with pollutants in the atmospheric boundary layer

    Science.gov (United States)

    Holmes, Heather A.

    Under the Clean Air Act, the U.S. Environmental Protection Agency is required to determine which air pollutants are harmful to human health, then regulate, monitor and establish criteria levels for these pollutants. To accomplish this and for scientific advancement, integration of knowledge from several disciplines is required including: engineering, atmospheric science, chemistry and public health. Recently, a shift has been made to establish interdisciplinary research groups to better understand the atmospheric processes that govern the transport of pollutants and chemical reactions of species in the atmospheric boundary layer (ABL). The primary reason for interdisciplinary collaboration is the need for atmospheric processes to be treated as a coupled system, and to design experiments that measure meteorological, chemical and physical variables simultaneously so forecasting models can be improved (i.e., meteorological and chemical process models). This dissertation focuses on integrating research disciplines to provide a more complete framework to study pollutants in the ABL. For example, chemical characterization of particulate matter (PM) and the physical processes governing PM distribution and mixing are combined to provide more comprehensive data for source apportionment. Data from three field experiments were utilized to study turbulence, meteorological and chemical parameters in the ABL. Two air quality field studies were conducted on the U.S./Mexico border. The first was located in Yuma, AZ to investigate the spatial and temporal variability of PM in an urban environment and relate chemical properties of ambient aerosols to physical findings. The second border air quality study was conducted in Nogales, Sonora, Mexico to investigate the relationship between indoor and outdoor air quality in order to better correlate cooking fuel types and home activities to elevated indoor PM concentrations. The final study was executed in southern Idaho and focused on

  19. Property Valuation and Radioactive Materials Transportation: A Legal, Economic and Public Perception Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Holm, J. A.; Thrower, A. W.; Widmayer, D. A.; Portner, W.

    2003-02-26

    The shipment of transuranic (TRU) radioactive waste to the Waste Isolation Pilot Plant (WIPP) in New Mexico raised a serious socioeconomic issue - the potential devaluation of property values due to the transportation of TRU waste from generator sites to the disposal facility. In 1992, the New Mexico Supreme Court held in City of Santa Fe v. Komis that a loss in value from public perception of risk was compensable. This issue has become an extremely important one for the development of the Yucca Mountain repository in Nevada for disposal of spent nuclear fuel and high-level radioactive waste. Much research has been conducted about the potential impacts of transportation of spent fuel and radioactive waste. This paper examines the pertinent studies conducted since the Komis case. It examines how the public debate on radioactive materials transportation continues and is now focused on transportation of high-level waste and spent nuclear fuel to the proposed Yucca Mountain repository. Finally, the paper suggests a path forward DOE can take to address this issue.

  20. Charge transport properties of bulk Ta3N5 from first principles

    Science.gov (United States)

    Morbec, Juliana M.; Galli, Giulia

    2016-01-01

    Tantalum nitride is considered a promising material for photoelectrochemical water splitting, however, its charge transport properties remain poorly understood. We investigated polaronic and band transport in Ta3N5 using first-principles calculations. We first studied the formation of small polarons using density-functional theory (DFT) including DFT +U and hybrid functionals. We found that electron small polarons may occur but hole polarons are not energetically favorable. The estimated polaronic mobility for electrons is at least three orders of magnitude smaller than that measured in Ta3N5 films, suggesting that the main transport mechanism for both electrons and holes is bandlike. Since band transport is strongly affected by the carrier effective masses, and Ta3N5 is known to have large electron and hole effective masses, we also investigated whether substitutional impurities or strain may help lower the effective masses. We found a significant reduction in both electron and hole effective masses (up to 17% for electrons and 39% for holes) under applied strain, which may lead to a substantial improvement (up to 30% for electrons and 15% for holes) in the carrier mobilities.

  1. Integrating-Sphere Measurements for Determining Optical Properties of Tissue-Engineered Oral Mucosa

    Science.gov (United States)

    Ionescu, A. M.; Cardona, J. C.; Garzón, I.; Oliveira, A. C.; Ghinea, R.; Alaminos, M.; Pérez, M. M.

    2015-02-01

    Surgical procedures carried out in the oral and maxillofacial region can result in large tissue defects. Accounting for the shortage of oral mucosa to replace the excised tissues, different models of an organotypic substitute of the oral mucosa generated by tissue engineering have recently been proposed. In this work, the propagation of light radiation through artificial human oral mucosa substitutes based on fibrin-agarose scaffolds (fibrin, fibrin-0.1% agarose, fibrin-0.2%agarose) is investigated, and their optical properties are determined using the inverse adding-doubling (IAD) method based on integrating-sphere measurements. Similar values for the absorption and scattering coefficients between the fibrin and fibrin-0.1% agarose bioengineered tissues and the native oral mucosa were found. These results suggest the adequacy of these biomaterials for potential clinical use in human oral mucosa applications. These optical properties represent useful references and data for applications requiring the knowledge of the light transport through this type of tissues, applications used in clinical practice. It also provides a new method of information analysis for the quality control of the development of the artificial nanostructured oral mucosa substitutes and its comparison with native oral mucosa tissues.

  2. Transport, geometrical, and topological properties of stealthy disordered hyperuniform two-phase systems.

    Science.gov (United States)

    Zhang, G; Stillinger, F H; Torquato, S

    2016-12-28

    Disordered hyperuniform many-particle systems have attracted considerable recent attention, since they behave like crystals in the manner in which they suppress large-scale density fluctuations, and yet also resemble statistically isotropic liquids and glasses with no Bragg peaks. One important class of such systems is the classical ground states of "stealthy potentials." The degree of order of such ground states depends on a tuning parameter χ. Previous studies have shown that these ground-state point configurations can be counterintuitively disordered, infinitely degenerate, and endowed with novel physical properties (e.g., negative thermal expansion behavior). In this paper, we focus on the disordered regime (0 two-phase media by circumscribing each point with a possibly overlapping sphere of a common radius a: the "particle" and "void" phases are taken to be the space interior and exterior to the spheres, respectively. The hyperuniformity of such two-phase media depends on the sphere sizes: While it was previously analytically proven that the resulting two-phase media maintain hyperuniformity if spheres do not overlap, here we show numerically that they lose hyperuniformity whenever the spheres overlap. We study certain transport properties of these systems, including the effective diffusion coefficient of point particles diffusing in the void phase as well as static and time-dependent characteristics associated with diffusion-controlled reactions. Besides these effective transport properties, we also investigate several related structural properties, including pore-size functions, quantizer error, an order metric, and percolation thresholds. We show that these transport, geometrical, and topological properties of our two-phase media derived from decorated stealthy ground states are distinctly different from those of equilibrium hard-sphere systems and spatially uncorrelated overlapping spheres. As the extent of short-range order increases, stealthy disordered

  3. Determining the thermal and physicals properties of oil processing products

    Directory of Open Access Journals (Sweden)

    Viktoria I. Kryvda

    2015-03-01

    Full Text Available In the last decades both technological process’ improvement and primary energy resources saving are the main tasks of oil refineries. Using various oil products does impose an accurate knowledge of their properties. The dispersion analysis applied makes possible to construct a model simulating the primary oil refining products’ and raw materials’ thermal physical properties. As a result of data approximation there were obtained polynomials with coefficients differing from attributable to the studied oil products fractions. The research represents graphic dependences of thermal physical properties on temperature values for diesel oil fraction. The linear character of density and calorific capacity dependencies from temperature is represented with a proportional error in calculations. The relative minimum error is below 2% that confirms the implemented calculations’ adequacy. The resulting model can be used in calculations for further technological process improvements.

  4. An Assessment of Transport Property Estimation Methods for Ammonia–Water Mixtures and Their Influence on Heat Exchanger Size

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Modi, Anish; Jensen, Jonas Kjær

    2015-01-01

    are considered: a flue-gas-based heat recovery boiler for a combined cycle power plant and a hot-oil-based boiler for a solar thermal power plant. The different transport property methods resulted in larger differences at high pressures and temperatures, and a possible discontinuous first derivative, when using...... the interpolative methods in contrast to the corresponding state methods. Nevertheless, all possible mixture transport property combinations used herein resulted in a heat exchanger size within 4.3 % difference for the flue-gas heat recovery boiler, and within 12.3 % difference for the oil-based boiler.......Transport properties of fluids are indispensable for heat exchanger design. The methods for estimating the transport properties of ammonia–water mixtures are not well established in the literature. The few existent methods are developed from none or limited, sometimes inconsistent experimental...

  5. Transport properties of non-conformal gluonic matter from compactified D4 branes

    CERN Document Server

    Wu, Chao; Huang, Mei

    2015-01-01

    We investigate non-conformal transport properties of gluonic matter via the fluid/gravity correspondence from compactified D4 branes. The D4-D6 model and the Sakai-Sugimoto (SS) model are two non-conformal holographic QCD models from top- down, whose background is the compactified D4 black branes under the near horizon limit. By using the dimensional reduction technique, we derive a 5D Einstein gravity minimally coupled with 3 scalar fields from the 10D D4 brane background. Following the boundary derivative expansion formalism of fluid/gravity correspondence, we obtain for the first time all the first order transport coefficients separately for non-conformal gluonic matter, and the ratio of the bulk to shear viscosity and the sound speed are consistent with former studies.

  6. Transport properties of hydrogen passivated silicon nanotubes and silicon nanotube field effect transistors

    KAUST Repository

    Montes Muñoz, Enrique

    2017-01-24

    We investigate the electronic transport properties of silicon nanotubes attached to metallic electrodes from first principles, using density functional theory and the non-equilibrium Green\\'s function method. The influence of the surface termination is studied as well as the dependence of the transport characteristics on the chirality, diameter, and length. Strong electronic coupling between nanotubes and electrodes is found to be a general feature that results in low contact resistance. The conductance in the tunneling regime is discussed in terms of the complex band structure. Silicon nanotube field effect transistors are simulated by applying a uniform potential gate. Our results demonstrate very high values of transconductance, outperforming the best commercial silicon field effect transistors, combined with low values of sub-threshold swing.

  7. Naphthodipyrrolidone (NDP) Based Conjugated Polymers with High Electron Mobility and Ambipolar Transport Properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haichang; Zhang, Shuo; Mao, Yifan; Liu, Kewei; Chen, Yu-Ming; Jiang, Zhang; Strzalka, Joseph; Yang, Wenjun; Wang, Chien-Lung; Zhu, Yu

    2017-06-07

    Two novel donor-acceptor pi-conjugated polymers based on naphthodipyrrolidone (NDP) were synthesized and characterized. The polymers possess low band gaps and suitable molecular orbital levels as ambipolar semiconductors. The thin film organic field effect transistor of NDP polymers exhibited ambipolar transport properties with a high electron mobility up to 0.67 cm(2) V-1 s(-1). The grazing-incidence wide-angle X-ray scattering (GIWAXS) studies demonstrated that the polymer molecules pack into a long-range-ordered lamellar structure with isotropically oriented crystalline domains. Thermal annealing promoted edge-on lamellar stacking as evidenced by the increased diffraction intensity along the out-of-plane direction. The polymer with NDP and bithiophene units achieved the best edge-on lamellar stacking after thermal annealing, which yielded the best electron transport performance in this work.

  8. Electronic and Quantum Transport Properties of Atomically Identified Si Point Defects in Graphene.

    Science.gov (United States)

    Lopez-Bezanilla, Alejandro; Zhou, Wu; Idrobo, Juan-Carlos

    2014-05-15

    We report high-resolution scanning transmission electron microscopy images displaying a range of inclusions of isolated silicon atoms at the edges and inner zones of graphene layers. Whereas the incorporation of Si atoms to a graphene armchair edge involves no reconstruction of the neighboring carbon atoms, the inclusion of a Si atom to a zigzag graphene edge entails the formation of five-membered carbon rings. In all the observed atomic edge terminations, a Si atom is found bridging two C atoms in a 2-fold coordinated configuration. The atomic-scale observations are underpinned by first-principles calculations of the electronic and quantum transport properties of the structural anomalies. Experimental estimations of Si-doped graphene band gaps realized by means of transport measurements may be affected by a low doping rate of 2-fold coordinated Si atoms at the graphene edges, and 4-fold coordinated at inner zones due to the apparition of mobility gaps.

  9. Photo-transport properties of Pb2CrO5 single crystals

    Science.gov (United States)

    Mondal, P. S.; Okazaki, R.; Taniguchi, H.; Terasaki, I.

    2014-11-01

    We report photo-thermoelectric transport phenomena in Pb2CrO5 single crystals. Without illumination, this material exhibits an insulating behavior characterized by an activation-type temperature variation of the electrical conductivity. The Seebeck coefficient contrastingly shows a crossover from high-temperature insulating to low-temperature metallic behavior, which is attributed to degenerate carriers in a donor level. We have found that under illumination, both the conductivity and the Seebeck coefficient increase in magnitude with increasing photon flux density in the degenerate-conduction regime. This result is difficult to understand within a simple photo-doping effect, which usually leads to a decrease in the Seebeck coefficient under illumination. The observed phenomenon is discussed in terms of a two-carrier contribution to the transport properties.

  10. Photo-transport properties of Pb{sub 2}CrO{sub 5} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, P. S.; Okazaki, R., E-mail: okazaki.ryuji@cc.nagoya-u.ac.jp; Taniguchi, H.; Terasaki, I. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2014-11-21

    We report photo-thermoelectric transport phenomena in Pb{sub 2}CrO{sub 5} single crystals. Without illumination, this material exhibits an insulating behavior characterized by an activation-type temperature variation of the electrical conductivity. The Seebeck coefficient contrastingly shows a crossover from high-temperature insulating to low-temperature metallic behavior, which is attributed to degenerate carriers in a donor level. We have found that under illumination, both the conductivity and the Seebeck coefficient increase in magnitude with increasing photon flux density in the degenerate-conduction regime. This result is difficult to understand within a simple photo-doping effect, which usually leads to a decrease in the Seebeck coefficient under illumination. The observed phenomenon is discussed in terms of a two-carrier contribution to the transport properties.

  11. Effect of substitutional impurities on the electronic transport properties of graphene

    Science.gov (United States)

    Berdiyorov, G. R.; Bahlouli, H.; Peeters, F. M.

    2016-10-01

    Density-functional theory in combination with the nonequilibrium Green's function formalism is used to study the effect of substitutional doping on the electronic transport properties of hydrogen passivated zig-zag graphene nanoribbon devices. B, N and Si atoms are used to substitute carbon atoms located at the center or at the edge of the sample. We found that Si-doping results in better electronic transport as compared to the other substitutions. The transmission spectrum also depends on the location of the substitutional dopants: for single atom doping the largest transmission is obtained for edge substitutions, whereas substitutions in the middle of the sample give larger transmission for double carbon substitutions. The obtained results are explained in terms of electron localization in the system due to the presence of impurities.

  12. A comparative study of proton transport properties of zirconium phosphate and its metal exchanged phases

    Indian Academy of Sciences (India)

    Rakesh Thakkar; Heemanshu Patel; Uma Chudasama

    2007-06-01

    A new phase of amorphous zirconium phosphate (ZrP), an inorganic ion exchanger of the class of tetravalent metal acid (TMA) salt, is synthesized by sol–gel method. The protons present in the structural hydroxyl groups indicate good potential for TMA salts to exhibit solid state proton conduction. Cu2+ and Li+ are exchanged onto ZrP to yield CuZrP and LiZrP exchanged phases. All these materials were characterized for elemental analysis (ICP–AES), thermal analysis (TGA, DSC), X-ray analysis and FTIR spectroscopy. The transport properties of these materials were explored and compared by measuring conductance at different temperatures using an impedance analyser. It is observed that conductivity decreases with increasing temperature in all cases and mechanism of transportation is proposed to be Grotthuss type. Conductivity performance of ZrP, CuZrP and LiZrP is discussed based on conductivity data and activation energy.

  13. Transmission and transport properties in Cantor graphene structures: The case of magnetoelectric modulation

    Science.gov (United States)

    Rodríguez-González, R.; Rodríguez-Vargas, I.

    2017-04-01

    We discuss theoretically the transmission and transport properties of Dirac electrons in a Cantor graphene system under magnetoelectric effects. The transfer matrix method and the Landauer-Büttiker formalism have been implemented to compute the transmittance and the linear-regime conductance, respectively. The fractal order of Cantor type together with the magnetic and electric field are used to distribute and generate the magnetoelectric barriers. This system give us the possibility of compare the mentioned physical properties for magnetic and magnetoelectric barriers. We found a bifurcation process in the transmission spectra which is observable when the generation increases. Also, an asymmetrical and symmetrical behavior is presented for magnetic and magnetoelectric barriers, respectively. In general, an oscillatory behavior is manifested in the conductance. Moreover, we can describe the peaks (form and location) that give rise to the oscillations through the contour plots of the transmittance in the (E ,ky) space. Likewise, by increasing the generation of the system the conductance is enhanced, the oscillations reduced and less pronounced. In short, the magnetoelectric modulation along with the fractal order can be used to control the transmission and transport properties in graphene-based structures.

  14. Magnetic, transport and structural properties of Co/Ir multilayers grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Colis, S.; Dinia, A.; Ulhaq-Bouillet, C.; Panissod, P.; Meny, C.; Schmerber, G.; Arabski, J. [IPCMS-GEMME (UMR 7504 du CNRS), 23 rue du Loess, BP 34, F-67034 Strasbourg Cedex 2 (France)

    2003-09-01

    We report on the structural properties of a [Co{sub 30}/Ir{sub 10}]{sub 10} {sub x} (A) superlattice, as well as on the magnetic and transport properties of a Co{sub 15}/Ir{sub 5}/Co{sub 30} (A) artificial ferrimagnetic system. The samples were grown by molecular beam epitaxy (MBE) on MgO(001) substrates covered with a Ir{sub 130} (A) buffer layer. High resolution cross section and plan view transmission electron microscopy (TEM) images present a high quality epitaxial stack [100]MgO(001) parallel [100]Ir(001) parallel [100]Co(001), with a tetragonalization of the Co fcc structure, due to strains induced by the Ir buffer. TEM images also show that the Co/Ir interfaces are flat, while the layers are continuous and free of bridges. These observations are consistent with zero field nuclear magnetic resonance measurements which indicate an fcc structure of the Co layers, and an interface mixing between Co and Ir limited to one atomic layer. As a consequence the antiferromagnetically coupled Co/Ir/Co sandwich presents large saturation and coercive fields which exceed 20 kOe and 220 Oe, respectively. Annealing made on the same sandwich indicate that the magnetic and transport properties are stable up to 300 C. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Pressure tuning of the electrical transport properties of the Weyl semimetal NbP

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Ricardo dos; Ajeesh, M.O.; Sun, Yan; Shekhar, Chandra; Schmidt, Marcus; Felser, Claudia; Yan, Binghai; Nicklas, Michael [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)

    2016-07-01

    Recently enormous attention has been given to a class of material called Weyl semimetal (WSM) due to the prediction of many exotic phenomena, in particular exceptional transport properties, making these systems not only interesting for fundamental research, but also promising materials for novel applications. WSM can be viewed as the hybrid of 3D graphene and topological insulators. The band crossing point, the so-called Weyl point, acts as a magnetic monopole (a singular point of Berry curvature) in momentum space, which always comes in a pairs. If the time-reversal and inversion symmetries are respected, a pair of Weyl points is degenerate in energy, forming another topological phase called Dirac semimetal. Owing this complex band structure the details of the electronic structure can play a significant role in the electrical transport properties of these materials. In this context, external pressure is an important control parameter to effectively tune lattice structures and the corresponding electronic states in a systematic fashion, avoiding the complexity brought by chemical doping. Here, we present a high pressure study of the magnetotransport properties of the Weyl semimetal NbP, which are particularly important to explore novel phenomena and understand the physics behind.

  16. Transport Properties of the Organic Conductor (TMTSF)2BrO4: Evidence of Variable Range Hopping

    DEFF Research Database (Denmark)

    Mortensen, Kell; Jacobsen, Claus Schelde; Bechgaard, Klaus

    1984-01-01

    A study of d.c. and microwave conductivity and thermoelectric power of the organic conductor (TMTSF)2BrO4 is presented. The transport properties are in qualitative agreement with charge transport via variable-range hopping among localized states. The localization is attributed to the anions, which...

  17. Quantitative characterization of the microstructure and transport properties of biopolymer networks

    Science.gov (United States)

    Jiao, Yang; Torquato, Salvatore

    2012-06-01

    Biopolymer networks are of fundamental importance to many biological processes in normal and tumorous tissues. In this paper, we employ the panoply of theoretical and simulation techniques developed for characterizing heterogeneous materials to quantify the microstructure and effective diffusive transport properties (diffusion coefficient De and mean survival time τ) of collagen type I networks at various collagen concentrations. In particular, we compute the pore-size probability density function P(δ) for the networks and present a variety of analytical estimates of the effective diffusion coefficient De for finite-sized diffusing particles, including the low-density approximation, the Ogston approximation and the Torquato approximation. The Hashin-Strikman upper bound on the effective diffusion coefficient De and the pore-size lower bound on the mean survival time τ are used as benchmarks to test our analytical approximations and numerical results. Moreover, we generalize the efficient first-passage-time techniques for Brownian-motion simulations in suspensions of spheres to the case of fiber networks and compute the associated effective diffusion coefficient De as well as the mean survival time τ, which is related to nuclear magnetic resonance relaxation times. Our numerical results for De are in excellent agreement with analytical results for simple network microstructures, such as periodic arrays of parallel cylinders. Specifically, the Torquato approximation provides the most accurate estimates of De for all collagen concentrations among all of the analytical approximations we consider. We formulate a universal curve for τ for the networks at different collagen concentrations, extending the work of Torquato and Yeong (1997 J. Chem. Phys. 106 8814). We apply rigorous cross-property relations to estimate the effective bulk modulus of collagen networks from a knowledge of the effective diffusion coefficient computed here. The use of cross-property relations

  18. Linking aquifer spatial properties and non-Fickian transport in mobile-immobile like alluvial settings

    Science.gov (United States)

    Zhang, Yong; Green, Christopher T.; Baeumer, Boris

    2014-01-01

    Time-nonlocal transport models can describe non-Fickian diffusion observed in geological media, but the physical meaning of parameters can be ambiguous, and most applications are limited to curve-fitting. This study explores methods for predicting the parameters of a temporally tempered Lévy motion (TTLM) model for transient sub-diffusion in mobile–immobile like alluvial settings represented by high-resolution hydrofacies models. The TTLM model is a concise multi-rate mass transfer (MRMT) model that describes a linear mass transfer process where the transfer kinetics and late-time transport behavior are controlled by properties of the host medium, especially the immobile domain. The intrinsic connection between the MRMT and TTLM models helps to estimate the main time-nonlocal parameters in the TTLM model (which are the time scale index, the capacity coefficient, and the truncation parameter) either semi-analytically or empirically from the measurable aquifer properties. Further applications show that the TTLM model captures the observed solute snapshots, the breakthrough curves, and the spatial moments of plumes up to the fourth order. Most importantly, the a priori estimation of the time-nonlocal parameters outside of any breakthrough fitting procedure provides a reliable “blind” prediction of the late-time dynamics of subdiffusion observed in a spectrum of alluvial settings. Predictability of the time-nonlocal parameters may be due to the fact that the late-time subdiffusion is not affected by the exact location of each immobile zone, but rather is controlled by the time spent in immobile blocks surrounding the pathway of solute particles. Results also show that the effective dispersion coefficient has to be fitted due to the scale effect of transport, and the mean velocity can differ from local measurements or volume averages. The link between medium heterogeneity and time-nonlocal parameters will help to improve model predictability for non

  19. Scaling of plant size and age emerges from linked aboveground and belowground transport network properties

    Science.gov (United States)

    Manzoni, S.; Hunt, A. G.

    2016-12-01

    Vegetation growth modulates cycling of water, carbon, and nutrients at local-to-global scales. It is therefore critical to quantify plant growth rates and how they are constrained by environmental conditions (especially limited resource availability). Various theoretical approaches have been proposed to this aim. Specifically, allometric theory provides a powerful tool to describe plant growth form and function, but it is focused on the properties of plant xylem networks, neglecting any role played by soils in supplying water to plants. On the other hand, percolation theory addresses physical constraints imposed by the soil pore network to water and nutrient transport, neglecting roles of root networks and vegetation taking up soil resources. In this contribution, we merge these two perspectives to derive scaling relations between plant size (namely height) and age. Our guiding hypothesis is that the root network expands in the soil at a rate sufficient to match the rate of transport of water and nutrients in an idealized optimal fractal pore network, as predicted by percolation theory; with nutrient transport distance vs. time scaling exponent 0.82, and water transport (saturated conditions) distance vs. time scaling exponent 1. The root expansion rate is mirrored by growth aboveground, as in allometric theory, which predicts an isometric relation between root extension and plant height. Building on these results, we predict that the scaling of plant height and age should also have exponent 0.82 in natural systems where nutrients are heterogeneously distributed, and 1 in fertilized systems where nutrients are homogeneously distributed. These predictions are successfully tested with extensive datasets covering major plant functional types worldwide, showing that soil and root network properties constrain vegetation growth by setting limits to the rates of water and nutrient supply to plants.

  20. The Effect of Twin Grain Boundary Tuned by Temperature on the Electrical Transport Properties of Monolayer MoS2

    Directory of Open Access Journals (Sweden)

    Luojun Du

    2016-09-01

    Full Text Available Theoretical calculation and experimental measurement have shown that twin grain boundary (GB of molybdenum disulphide (MoS2 exhibits extraordinary effects on transport properties. Precise transport measurements need to verify the transport mechanism of twin GB in MoS2. Here, monolayer molybdenum disulphide with a twin grain boundary was grown in our developed low-pressure chemical vapor deposition (CVD system, and we investigated how the twin GB affects the electrical transport properties of MoS2 by temperature-dependent transport studies. At low temperature, the twin GB can increase the in-plane electrical conductivity of MoS2 and the transport exhibits variable-range hopping (VRH, while at high temperature, the twin GB impedes the electrical transport of MoS2 and the transport exhibits nearest-neighbor hopping (NNH. Our results elucidate carrier transport mechanism of twin GB and give an important indication of twin GB in tailoring the electronic properties of MoS2 for its applications in next-generation electronics and optoelectronic devices.