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Sample records for transporter msba interacts

  1. Investigating the dynamic nature of the ABC transporters: ABCB1 and MsbA as examples for the potential synergies of MD theory and EPR applications.

    Science.gov (United States)

    Stockner, Thomas; Mullen, Anna; MacMillan, Fraser

    2015-10-01

    ABC transporters are primary active transporters found in all kingdoms of life. Human multidrug resistance transporter ABCB1, or P-glycoprotein, has an extremely broad substrate spectrum and confers resistance against chemotherapy drug treatment in cancer cells. The bacterial ABC transporter MsbA is a lipid A flippase and a homolog to the human ABCB1 transporter, with which it partially shares its substrate spectrum. Crystal structures of MsbA and ABCB1 have been solved in multiple conformations, providing a glimpse into the possible conformational changes the transporter could be going through during the transport cycle. Crystal structures are inherently static, while a dynamic picture of the transporter in motion is needed for a complete understanding of transporter function. Molecular dynamics (MD) simulations and electron paramagnetic resonance (EPR) spectroscopy can provide structural information on ABC transporters, but the strength of these two methods lies in the potential to characterise the dynamic regime of these transporters. Information from the two methods is quite complementary. MD simulations provide an all atom dynamic picture of the time evolution of the molecular system, though with a narrow time window. EPR spectroscopy can probe structural, environmental and dynamic properties of the transporter in several time regimes, but only through the attachment sites of an exogenous spin label. In this review the synergistic effects that can be achieved by combining the two methods are highlighted, and a brief methodological background is also presented. © 2015 Authors; published by Portland Press Limited.

  2. Analysis of an ATP-induced conformational transition of ABC transporter MsbA using a coarse-grained model.

    Science.gov (United States)

    Arai, Naoki; Furuta, Tadaomi; Sakurai, Minoru

    2017-01-01

    Upon the binding of ATP molecules to nucleotide binding domains (NBDs), ATP-binding cassette (ABC) exporters undergo a conformational transition from an inward-facing (IF) to an outward-facing (OF) state. This molecular event is a typical example of chemo-mechanical coupling. However, the underlying mechanism remains unclear. In this study, we analyzed the IF→OF transition of a representative ABC exporter, MsbA, by solving the equation of motion under an elastic network model (ENM). ATP was represented as a single node in ENM or replaced by external forces. When two ATP nodes were added to the ENM of the IF state protein, the two NBDs dimerized; subsequently, the two transmembrane domains opened toward the extracellular side, resulting in the formation of the OF structure. Such a conformational transition was also reproduced by applying external forces, which caused the rotational motion of the NBDs instead of the addition of ATP nodes. The process of the conformational transition was analyzed in detail using cross-correlation maps for node-node interactions. More importantly, it was revealed that the ATP binding energy is converted into distortion energy of several transmembrane helices. These results are useful for understanding the chemo-mechanical coupling in ABC transporters.

  3. Analysis of the structural and functional roles of coupling helices in the ATP-binding cassette transporter MsbA through enzyme assays and molecular dynamics simulations.

    Science.gov (United States)

    Furuta, Tadaomi; Yamaguchi, Tomohiro; Kato, Hiroaki; Sakurai, Minoru

    2014-07-08

    ATP-binding cassette (ABC) transporters are constructed from some common structural units: the highly conserved nucleotide-binding domains (NBDs), which work as a nucleotide-dependent engine for driving substrate transport, the diverse transmembrane domains (TMDs), which create the translocation pathway, and the coupling helices (CHs), which are located at the NBD-TMD interface. Although the CHs are believed to be essential for NBD-TMD communication, their roles remain unclear. In this study, we performed enzyme assays and molecular dynamics (MD) simulations of the ABC transporter MsbA and two MsbA mutants in which the amino acid residues of one of the CHs were mutated to alanines: (i) wild type (Wt), (ii) CH1 mutant (Mt1), and (iii) CH2 mutant (Mt2). The experiments show that the CH2 mutation decreases the ATPase activity (kcat) compared with that of the Wt (a decrease of 32%), and a nearly equal degree of decrease in the ATP binding affinity (Km) was observed for both Mt1 and Mt2. The MD simulations successfully accounted for several structural and dynamical origins for these experimental observations. In addition, on the basis of collective motion and morphing analyses, we propose that the reverse-rotational motions and noddinglike motions between the NBDs and TMDs are indispensable for the conformational transition between the inward- and outward-facing conformations. In particular, CH2 is significantly important for the occurrence of the noddinglike motion. These findings provide important insights into the structure-function relationship of ABC transporters.

  4. Entropic Ratchet transport of interacting active Brownian particles

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Bao-Quan, E-mail: aibq@hotmail.com [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, 510006 Guangzhou (China); He, Ya-Feng [College of Physics Science and Technology, Hebei University, 071002 Baoding (China); Zhong, Wei-Rong, E-mail: wrzhong@jnu.edu.cn [Department of Physics and Siyuan Laboratory, College of Science and Engineering, Jinan University, 510632 Guangzhou (China)

    2014-11-21

    Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction.

  5. Entropic Ratchet transport of interacting active Brownian particles

    International Nuclear Information System (INIS)

    Ai, Bao-Quan; He, Ya-Feng; Zhong, Wei-Rong

    2014-01-01

    Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction

  6. Fluid-rock interaction: A reactive transport approach

    Energy Technology Data Exchange (ETDEWEB)

    Steefel, C.; Maher, K.

    2009-04-01

    Fluid-rock interaction (or water-rock interaction, as it was more commonly known) is a subject that has evolved considerably in its scope over the years. Initially its focus was primarily on interactions between subsurface fluids of various temperatures and mostly crystalline rocks, but the scope has broadened now to include fluid interaction with all forms of subsurface materials, whether they are unconsolidated or crystalline ('fluid-solid interaction' is perhaps less euphonious). Disciplines that previously carried their own distinct names, for example, basin diagenesis, early diagenesis, metamorphic petrology, reactive contaminant transport, chemical weathering, are now considered to fall under the broader rubric of fluid-rock interaction, although certainly some of the key research questions differ depending on the environment considered. Beyond the broadening of the environments considered in the study of fluid-rock interaction, the discipline has evolved in perhaps an even more important way. The study of water-rock interaction began by focusing on geochemical interactions in the absence of transport processes, although a few notable exceptions exist (Thompson 1959; Weare et al. 1976). Moreover, these analyses began by adopting a primarily thermodynamic approach, with the implicit or explicit assumption of equilibrium between the fluid and rock. As a result, these early models were fundamentally static rather than dynamic in nature. This all changed with the seminal papers by Helgeson and his co-workers (Helgeson 1968; Helgeson et al. 1969) wherein the concept of an irreversible reaction path was formally introduced into the geochemical literature. In addition to treating the reaction network as a dynamically evolving system, the Helgeson studies introduced an approach that allowed for the consideration of a multicomponent geochemical system, with multiple minerals and species appearing as both reactants and products, at least one of which could be

  7. Transporter-mediated natural product–drug interactions for the treatment of cardiovascular diseases

    Directory of Open Access Journals (Sweden)

    Weibin Zha

    2018-04-01

    Full Text Available The growing use of natural products in cardiovascular (CV patients has been greatly raising the concerns about potential natural product–CV drug interactions. Some of these may lead to unexpected cardiovascular adverse effects and it is, therefore, essential to identify or predict potential natural product–CV drug interactions, and to understand the underlying mechanisms. Drug transporters are important determinants for the pharmacokinetics of drugs and alterations of drug transport has been recognized as one of the major causes of natural product–drug interactions. In last two decades, many CV drugs (e.g., angiotensin II receptor blockers, beta-blockers and statins have been identified to be substrates and inhibitors of the solute carrier (SLC transporters and the ATP-binding cassette (ABC transporters, which are two major transporter superfamilies. Meanwhile, in vitro and in vivo studies indicate that a growing number of natural products showed cardioprotective effects (e.g., gingko biloba, danshen and their active ingredients are also substrates and inhibitors of drug transporters. Thus, to understand transporter-mediated natural product–CV drug interactions is important and some transporter-mediated interactions have already shown to have clinical relevance. In this review, we review the current knowledge on the role of ABC and SLC transporters in CV therapy, as well as transporter modulation by natural products used in CV diseases and their induced natural product–CV drug interactions through alterations of drug transport. We hope our review will aid in a comprehensive summary of transporter-mediated natural product–CV drug interactions and help public and physicians understand these type of interactions. Keywords: Cardiovascular drugs, Natural products, Drug transporters, Natural product–drug interaction, Pharmacokinetics

  8. Interactions between co-expressed Arabidopsis sucrose transporters in the split-ubiquitin system

    Directory of Open Access Journals (Sweden)

    Lalonde Sylvie

    2003-03-01

    Full Text Available Abstract Background The Arabidopsis genome contains nine sucrose transporter paralogs falling into three clades: SUT1-like, SUT2 and SUT4. The carriers differ in their kinetic properties. Many transport proteins are known to exist as oligomers. The yeast-based split ubiquitin system can be used to analyze the ability of membrane proteins to interact. Results Promoter-GUS fusions were used to analyze the cellular expression of the three transporter genes in transgenic Arabidopsis plants. All three fusion genes are co-expressed in companion cells. Protein-protein interactions between Arabidopsis sucrose transporters were tested using the split ubiquitin system. Three paralogous sucrose transporters are capable of interacting as either homo- or heteromers. The interactions are specific, since a potassium channel and a glucose transporter did not show interaction with sucrose transporters. Also the biosynthetic and metabolizing enzymes, sucrose phosphate phosphatase and sucrose synthase, which were found to be at least in part bound to the plasma membrane, did not specifically interact with sucrose transporters. Conclusions The split-ubiquitin system provides a powerful tool to detect potential interactions between plant membrane proteins by heterologous expression in yeast, and can be used to screen for interactions with membrane proteins as baits. Like other membrane proteins, the Arabidopsis sucrose transporters are able to form oligomers. The biochemical approaches are required to confirm the in planta interaction.

  9. Simulating the Interactions Among Land Use, Transportation ...

    Science.gov (United States)

    In most transportation studies, computer models that forecast travel behavior statistics for a future year use static projections of the spatial distribution of future population and employment growth as inputs. As a result, they are unable to account for the temporally dynamic and non-linear interactions among transportation, land use, and socioeconomic systems. System dynamics (SD) provides a common framework for modeling the complex interactions among transportation and other related systems. This study uses a SD model to simulate the cascading impacts of a proposed light rail transit (LRT) system in central North Carolina, USA. The Durham-Orange Light Rail Project (D-O LRP) SD model incorporates relationships among the land use, transportation, and economy sectors to simulate the complex feedbacks that give rise to the travel behavior changes forecasted by the region’s transportation model. This paper demonstrates the sensitivity of changes in travel behavior to the proposed LRT system and the assumptions that went into the transportation modeling, and compares those results to the impacts of an alternative fare-free transit system. SD models such as the D-O LRP SD model can complement transportation studies by providing valuable insight into the interdependent community systems that collectively contribute to travel behavior changes. Presented at the 35th International Conference of the System Dynamics Society in Cambridge, MA, July 18th, 2017

  10. Transporter-mediated natural product-drug interactions for the treatment of cardiovascular diseases.

    Science.gov (United States)

    Zha, Weibin

    2018-04-01

    The growing use of natural products in cardiovascular (CV) patients has been greatly raising the concerns about potential natural product-CV drug interactions. Some of these may lead to unexpected cardiovascular adverse effects and it is, therefore, essential to identify or predict potential natural product-CV drug interactions, and to understand the underlying mechanisms. Drug transporters are important determinants for the pharmacokinetics of drugs and alterations of drug transport has been recognized as one of the major causes of natural product-drug interactions. In last two decades, many CV drugs (e.g., angiotensin II receptor blockers, beta-blockers and statins) have been identified to be substrates and inhibitors of the solute carrier (SLC) transporters and the ATP-binding cassette (ABC) transporters, which are two major transporter superfamilies. Meanwhile, in vitro and in vivo studies indicate that a growing number of natural products showed cardioprotective effects (e.g., gingko biloba, danshen and their active ingredients) are also substrates and inhibitors of drug transporters. Thus, to understand transporter-mediated natural product-CV drug interactions is important and some transporter-mediated interactions have already shown to have clinical relevance. In this review, we review the current knowledge on the role of ABC and SLC transporters in CV therapy, as well as transporter modulation by natural products used in CV diseases and their induced natural product-CV drug interactions through alterations of drug transport. We hope our review will aid in a comprehensive summary of transporter-mediated natural product-CV drug interactions and help public and physicians understand these type of interactions. Copyright © 2017. Published by Elsevier B.V.

  11. Interactions between organic anions on multiple transporters in Caco-2 cells

    DEFF Research Database (Denmark)

    Grandvuinet, Anne Sophie; Steffansen, Bente

    2011-01-01

    Caco-2 cell line may be used as an overall model to predict interactions on multiple membrane transporters in the intestine. Taurocholic acid (TCA) and estrone-3-sulfate (E1S) were used as model substrates. Possible inhibitors studied were TCA, E1S, taurolithocholic acid, fluvastatin, and glipizide......-dependent bile acid transporter and the organic solute transporter α/β, and to less extent by the organic anion transporting polypeptide 2B1. However, interactions on efflux transporters were not detected, although they were expected from the literature on the investigated compounds. Biosimulation methods may...

  12. Transport coefficients of strongly interacting matter

    International Nuclear Information System (INIS)

    Heckmann, Klaus

    2011-01-01

    In this thesis, we investigate the dissipative transport phenomena of strongly interacting matter. The special interest is in the shear viscosity and its value divided by entropy density. The performed calculations are based on effective models for Quantum Chromodynamics, mostly focused on the 2-flavor Nambu-Jona-Lasinio model. This allows us to study the hadronic sector as well as the quark sector within one single model. We expand the models up to next-to-leading order in inverse numbers of colors. We present different possibilities of calculating linear transport coefficients and give an overview over qualitative properties as well as over recent ideas concerning ideal fluids. As present methods are not able to calculate the quark two-point function in Minkowski space-time in the self-consistent approximation scheme of the Nambu-Jona-Lasinio model, a new method for this purpose is developed. This self-energy parametrization method is applied to the expansion scheme, yielding the quark spectral function with meson back-coupling effects. The usage of this spectral function in the transport calculation is only one result of this work. We also test the application of different transport approaches in the NJL model, and find an interesting behavior of the shear viscosity at the critical end point of the phase diagram. We also use the NJL model to calculate the viscosity of a pion gas in the dilute regime. After an analysis of other models for pions and their interaction, we find that the NJL-result leads to an important modification of transport properties in comparison with the calculations which purely rely on pion properties in the vacuum. (orig.)

  13. Transport quasiparticles and transverse interactions in quark-gluon plasmas

    International Nuclear Information System (INIS)

    Baym, Gordon

    1996-01-01

    Calculations of the properties of interacting quark-gluon plasmas are beset by infrared divergences associated with the fact that magnetic interactions, i.e., those occurring through exchange of transverse gluons, are, in the absence of a 'magnetic mass''in QCD, not screened. In this lecture we discuss the effects of magnetic interactions on the transport coefficients and the quasiparticle structure of quark-gluon plasmas. We describe how inclusion of dynamical screening effects - corresponding to Landau damping of the virtual quanta exchanged - leads to finite transport scattering rates. In the weak coupling limit, dynamical screening effects dominate over a magnetic mass. We illustrate the breakdown of the quasi particle structure of degenerate plasmas caused by long-ranged magnetic interactions, describe the structure of fermion quasiparticles in hot relativistic plasmas, and touch briefly on the problem of the lifetime of quasiparticle in the presence of long-ranged magnetic interactions. (author)

  14. Selected Topics on Mass Transport in Gas-solid Interactions

    DEFF Research Database (Denmark)

    Somers, Marcel A.J.

    2004-01-01

    The present article is a short review containing examples of the role of mass transport in the solid state during gas-solid interactions. Examples are taken from the authors' research on the interaction of carbon and/or nitrogen with iron-based metals. Topics dealt with are diffusion-controlled d......The present article is a short review containing examples of the role of mass transport in the solid state during gas-solid interactions. Examples are taken from the authors' research on the interaction of carbon and/or nitrogen with iron-based metals. Topics dealt with are diffusion...... on the kinetics of phenomena in the solid state. Various experimental techniques were applied to investigate these phenomena; it is however beyond the scope of the present article to treat experimental conditions in detail. The interested reader is referred to the original work for in depth discussions...

  15. Analysis of Nanobody-Epitope Interactions in Living Cells via Quantitative Protein Transport Assays.

    Science.gov (United States)

    Früholz, Simone; Pimpl, Peter

    2017-01-01

    Over the past few decades, quantitative protein transport analyses have been used to elucidate the sorting and transport of proteins in the endomembrane system of plants. Here, we have applied our knowledge about transport routes and the corresponding sorting signals to establish an in vivo system for testing specific interactions between soluble proteins.Here, we describe the use of quantitative protein transport assays in tobacco mesophyll protoplasts to test for interactions occurring between a GFP-binding nanobody and its GFP epitope. For this, we use a secreted GFP-tagged α-amylase as a reporter together with a vacuolar-targeted RFP-tagged nanobody. The interaction between these proteins is then revealed by a transport alteration of the secretory reporter due to the interaction-triggered attachment of the vacuolar sorting signal.

  16. Interaction of coenzyme Q10 with the intestinal drug transporter P-glycoprotein.

    Science.gov (United States)

    Itagaki, Shirou; Ochiai, Akiko; Kobayashi, Masaki; Sugawara, Mitsuru; Hirano, Takeshi; Iseki, Ken

    2008-08-27

    In clinical trials, patients usually take many kinds of drugs at the same time. Thus, drug-drug interactions can often directly affect the therapeutic safety and efficacy of many drugs. Oral delivery is the most desirable means of drug administration. Changes in the activity of drug transporters may substantially influence the absorption of administered drugs from the intestine. However, there have been a few studies on food-drug interactions involving transporters. It is important to be aware of the potential of food-drug interactions and to act in order to prevent undesirable and harmful clinical consequences. Coenzyme Q10 (CoQ10) is very widely consumed by humans as a food supplement because of its recognition by the public as an important nutrient in supporting human health. Since intestinal efflux transporter P-glycoprotein (P-gp) is one of the major factors in drug-drug interactions, we focused on this transporter. We report here for the first time that CoQ10, which is widely used as a food supplement, affects the transport activity of P-gp.

  17. Interactions of Transportation and Telecommunications Behaviors

    Science.gov (United States)

    Dholakia, N.; Mundorf, N.; Dholakia, R. R.; Xiao, J. J.

    2002-05-01

    This project was designed as a social science complement to the engineering studies supported by the University of Rhode Island (URI) Transportation Center (URITC). The project developed a behavioral knowledge base about the actual and intended transport and telecommunications behaviors of transportation users, with a particular focus on southern Rhode Island. Background studies, drawing from literature on telecommuting and travel behavior, led to the development of a generalized framework to understand the transport-telecom interactions. In particular, we developed working papers dealing with transport aspects of e-retailing and distance education. In the empirical part of this project, two major field studies were completed. The first of these was a survey of URI students, probing their car travel, carpool, bus use, and Internet use behaviors. The students were surveyed first by telephone, selected randomly from a list obtained from the Register's office. A total of 220 students responded to the telephone survey. Characteristics of the telephone survey respondents are shown in Appendix B. This was supplemented by an in-class survey of 107 students conveniently selected from the courses taught by the research faculty. This supplementary questionnaire probed the students more deeply regarding their motivations for transportation and technology use issues. The second major field study was a mail survey of southern Rhode Island residents. In this survey, we not only investigated actual travel and transport behaviors but also measured attitudes towards the environment and alternative transport and telecommuting solutions. At the time of writing this report, about 850 individuals had responded to our mail questionnaire. Characteristics of the resident sample are described in Appendix B. The results have laid the groundwork for our second year project where we plan to study the impact of specific interventions on transportation and telecommuting attitudes and intentions.

  18. Coulombic interactions during advection-dominated transport of ions in porous media

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Stolze, Lucien; Rolle, Massimo

    2017-01-01

    bench-scale experiments and numerical simulations. The investigation aims at quantifying the key role of small-scale electrostatic interactions in flow-through systems, especially when advection is the dominant mass-transfer process. Considering dilute solutions of strong electrolytes (e.g., MgCl2......Solute transport of charged species in porous media is significantly affected by the electrochemical migration term resulting from the charge-induced interactions among dissolved ions and with solid surfaces. Therefore, the characterization of such Coulombic interactions and their effect...... on multicomponent ionic transport is of critical importance for assessing the fate of charged solutes in porous media. In this work we present a detailed investigation of the electrochemical effects during conservative multicomponent ionic transport in homogeneous and heterogeneous domains by means of laboratory...

  19. Prohibitin/annexin 2 interaction regulates fatty acid transport in adipose tissue

    Science.gov (United States)

    Salameh, Ahmad; Daquinag, Alexes C.; Staquicini, Daniela I.; An, Zhiqiang; Pasqualini, Renata; Kolonin, Mikhail G.

    2016-01-01

    We have previously identified prohibitin (PHB) and annexin A2 (ANX2) as proteins interacting on the surface of vascular endothelial cells in white adipose tissue (WAT) of humans and mice. Here, we demonstrate that ANX2 and PHB also interact in adipocytes. Mice lacking ANX2 have normal WAT vascularization, adipogenesis, and glucose metabolism but display WAT hypotrophy due to reduced fatty acid uptake by WAT endothelium and adipocytes. By using cell culture systems in which ANX2/PHB binding is disrupted either genetically or through treatment with a blocking peptide, we show that fatty acid transport efficiency relies on this protein complex. We also provide evidence that the interaction between ANX2 and PHB mediates fatty acid transport from the endothelium into adipocytes. Moreover, we demonstrate that ANX2 and PHB form a complex with the fatty acid transporter CD36. Finally, we show that the colocalization of PHB and CD36 on adipocyte surface is induced by extracellular fatty acids. Together, our results suggest that an unrecognized biochemical interaction between ANX2 and PHB regulates CD36-mediated fatty acid transport in WAT, thus revealing a new potential pathway for intervention in metabolic diseases. PMID:27468426

  20. Phytotherapeutics: The Emerging Role of Intestinal and Hepatocellular Transporters in Drug Interactions with Botanical Supplements.

    Science.gov (United States)

    Murtaza, Ghulam; Ullah, Naveed; Mukhtar, Farah; Nawazish, Shamyla; Muneer, Saiqa

    2017-10-21

    In herbalism, botanical supplements are commonly believed to be safe remedies, however, botanical supplements and dietary ingredients interact with transport and metabolic processes, affecting drug disposition. Although a large number of studies have described that botanical supplements interfere with drug metabolism, the mode of their interaction with drug transport processes is not well described. Such interactions may result in serious undesired effects and changed drug efficacy, therefore, some studies on interaction between botanical supplement ingredients and drug transporters such as P-gp and OATPs are described here, suggesting that the interaction between botanical supplements and the drug transporters is clinically significant.

  1. The Electron Transport Chain: An Interactive Simulation

    Science.gov (United States)

    Romero, Chris; Choun, James

    2014-01-01

    This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

  2. Interaction and Transport of Methamphetamine and its Primary Metabolites by Organic Cation and Multidrug and Toxin Extrusion Transporters.

    Science.gov (United States)

    Wagner, David J; Sager, Jennifer E; Duan, Haichuan; Isoherranen, Nina; Wang, Joanne

    2017-07-01

    Methamphetamine is one of the most abused illicit drugs with roughly 1.2 million users in the United States alone. A large portion of methamphetamine and its metabolites is eliminated by the kidney with renal clearance larger than glomerular filtration clearance. Yet the mechanism of active renal secretion is poorly understood. The goals of this study were to characterize the interaction of methamphetamine and its major metabolites with organic cation transporters (OCTs) and multidrug and toxin extrusion (MATE) transporters and to identify the major transporters involved in the disposition of methamphetamine and its major metabolites, amphetamine and para -hydroxymethamphetamine ( p -OHMA). We used cell lines stably expressing relevant transporters to show that methamphetamine and its metabolites inhibit human OCTs 1-3 (hOCT1-3) and hMATE1/2-K with the greatest potencies against hOCT1 and hOCT2. Methamphetamine and amphetamine are substrates of hOCT2, hMATE1, and hMATE2-K, but not hOCT1 and hOCT3. p -OHMA is transported by hOCT1-3 and hMATE1, but not hMATE2-K. In contrast, organic anion transporters 1 and 3 do not interact with or transport these compounds. Methamphetamine and its metabolites exhibited complex interactions with hOCT1 and hOCT2, suggesting the existence of multiple binding sites. Our studies suggest the involvement of the renal OCT2/MATE pathway in tubular secretion of methamphetamine and its major metabolites and the potential of drug-drug interactions with substrates or inhibitors of the OCTs. This information may be considered when prescribing medications to suspected or known abusers of methamphetamine to mitigate the risk of increased toxicity or reduced therapeutic efficacy. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

  3. Interaction and diffusion transport of americium in soils

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Guinart, Oriol; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Marti i Franques 1-11, 08028, Barcelona (Spain)

    2014-07-01

    The final disposal of High Level Radioactive Wastes (HLRW) is based on its long-term storage in underground facilities located in geological stable sites with a multi-barrier system, the so called Deep Geological Repositories (DGR), that will keep HLRW confined for >10.000 years. After this period of time, leachates rich in long-live radioisotopes might escape from DGR and start to transport towards the biosphere. There is still a lack of information concerning the interaction and transport in soils of some radionuclides present in HLRW, especially for radionuclides that present a high sorption, such as americium (Am). Having reliable information about the mobility of radionuclides in soils is crucial in order to develop risk assessment models and to take proper decisions in case of soil contamination. The aim of the present work was, by means of laboratory scale experiments, to study the interaction and, for first time, to evaluate the diffusion transport of {sup 241}Am in soils. The {sup 241}Am interaction in soils was assessed by applying sorption batch assays to 20 soil samples with contrasted edaphic properties which allowed us to quantify the solid-liquid distribution coefficient (K{sub d}) and desorption percentage. K{sub d} (Am) values ranged from 10{sup 3} to 10{sup 5} L kg{sup -1} and desorption percentages were always less than 2% which denoted a high capacity of the soil to incorporate the Am and a low reversibility of the sorption process. The influence of soil properties in {sup 241}Am interaction was studied by means of multiple linear and multivariate regressions. Although a single correlation between K{sub d} (Am) values and a soil property was not found, the main properties affecting {sup 241}Am interaction in soils were soil pH, carbonate and organic matter contents in the soil. Finally, additional batch assays at different controlled pH were done to study Am sorption as a function of the contact solution pH. A variation of the Am sorption

  4. Channel-facilitated molecular transport: The role of strength and spatial distribution of interactions

    Energy Technology Data Exchange (ETDEWEB)

    Uppulury, Karthik, E-mail: karthik.uppulury@gmail.com [Department of Chemistry, Texas Tech University, Lubbock, TX 79409 (United States); Kolomeisky, Anatoly B. [Department of Chemistry, Department of Chemical and Biomolecular Engineering, Center for Theoretical Biological Physics, Rice University, Houston, TX 77005 (United States)

    2016-12-20

    Highlights: • Molecular flux strongly depends on the strength of the molecule-pore interactions. • There exists an optimal molecule-pore interaction potential for maximal flux. • Volume of interactions depends inversely on the strength for maximal flux. • Stronger interactions need more number of attractive sites for maximal flux. • Channels with few special sites need more attractive sites for higher flux. - Abstract: Molecular transport across channels and pores is critically important for multiple natural and industrial processes. Recent advances in single-molecule techniques have allowed researchers to probe translocation through nanopores with unprecedented spatial and temporal resolution. However, our understanding of the mechanisms of channel-facilitated molecular transport is still not complete. We present a theoretical approach that investigates the role of molecular interactions in the transport through channels. It is based on the discrete-state stochastic analysis that provides a fully analytical description of this complex process. It is found that a spatial distribution of the interactions strongly influences the translocation dynamics. We predict that there is the optimal distribution that leads to the maximal flux through the channel. It is also argued that the channel transport depends on the strength of the molecule-pore interactions, on the shape of interaction potentials and on the relative contributions of entrance and diffusion processes in the system. These observations are discussed using simple physical-chemical arguments.

  5. Channel-facilitated molecular transport: The role of strength and spatial distribution of interactions

    International Nuclear Information System (INIS)

    Uppulury, Karthik; Kolomeisky, Anatoly B.

    2016-01-01

    Highlights: • Molecular flux strongly depends on the strength of the molecule-pore interactions. • There exists an optimal molecule-pore interaction potential for maximal flux. • Volume of interactions depends inversely on the strength for maximal flux. • Stronger interactions need more number of attractive sites for maximal flux. • Channels with few special sites need more attractive sites for higher flux. - Abstract: Molecular transport across channels and pores is critically important for multiple natural and industrial processes. Recent advances in single-molecule techniques have allowed researchers to probe translocation through nanopores with unprecedented spatial and temporal resolution. However, our understanding of the mechanisms of channel-facilitated molecular transport is still not complete. We present a theoretical approach that investigates the role of molecular interactions in the transport through channels. It is based on the discrete-state stochastic analysis that provides a fully analytical description of this complex process. It is found that a spatial distribution of the interactions strongly influences the translocation dynamics. We predict that there is the optimal distribution that leads to the maximal flux through the channel. It is also argued that the channel transport depends on the strength of the molecule-pore interactions, on the shape of interaction potentials and on the relative contributions of entrance and diffusion processes in the system. These observations are discussed using simple physical-chemical arguments.

  6. Proteoliposomes as Tool for Assaying Membrane Transporter Functions and Interactions with Xenobiotics

    Directory of Open Access Journals (Sweden)

    Annamaria Tonazzi

    2013-09-01

    Full Text Available Proteoliposomes represent a suitable and up to date tool for studying membrane transporters which physiologically mediate absorption, excretion, trafficking and reabsorption of nutrients and metabolites. Using recently developed reconstitution strategies, transporters can be inserted in artificial bilayers with the same orientation as in the cell membranes and in the absence of other interfering molecular systems. These methodologies are very suitable for studying kinetic parameters and molecular mechanisms. After the first applications on mitochondrial transporters, in the last decade, proteoliposomes obtained with optimized methodologies have been used for studying plasma membrane transporters and defining their functional and kinetic properties and structure/function relationships. A lot of information has been obtained which has clarified and completed the knowledge on several transporters among which the OCTN sub-family members, transporters for neutral amino acid, B0AT1 and ASCT2, and others. Transporters can mediate absorption of substrate-like derivatives or drugs, improving their bioavailability or can interact with these compounds or other xenobiotics, leading to side/toxic effects. Therefore, proteoliposomes have recently been used for studying the interaction of some plasma membrane and mitochondrial transporters with toxic compounds, such as mercurials, H2O2 and some drugs. Several mechanisms have been defined and in some cases the amino acid residues responsible for the interaction have been identified. The data obtained indicate proteoliposomes as a novel and potentially important tool in drug discovery.

  7. Spin-dependent transport through interacting graphene armchair nanoribbons

    International Nuclear Information System (INIS)

    Koller, Sonja; Mayrhofer, Leonhard; Grifoni, Milena

    2010-01-01

    We investigate spin effects in transport across fully interacting, finite-size graphene armchair nanoribbons (ACNs) contacted to collinearly spin-polarized leads. In such systems, the presence of short-range Coulomb interaction between bulk states and states localized at the ribbon ends leads to novel spin-dependent phenomena. Specifically, the total spin of the low-energy many-body states is conserved during tunneling but that of the bulk and end states is not. As a consequence, in the single-electron regime, dominated by Coulomb blockade phenomena, we find pronounced negative differential conductance features for ACNs contacted to parallel polarized leads. These features are, however, absent in an anti-parallel contact configuration, which in turn leads, within a certain gate and bias voltage region, to a negative tunneling magneto-resistance. Moreover, we analyze the changes in the transport characteristics under the influence of an external magnetic field.

  8. Quantum transport in strongly interacting one-dimensional nanostructures

    NARCIS (Netherlands)

    Agundez, R.R.

    2015-01-01

    In this thesis we study quantum transport in several one-dimensional systems with strong electronic interactions. The first chapter contains an introduction to the concepts treated throughout this thesis, such as the Aharonov-Bohm effect, the Kondo effect, the Fano effect and quantum state transfer.

  9. Predicting transporter-mediated drug interactions: Commentary on: "Pharmacokinetic evaluation of a drug transporter cocktail consisting of digoxin, furosemide, metformin and rosuvastatin" and "Validation of a microdose probe drug cocktail for clinical drug interaction assessments for drug transporters and CYP3A".

    Science.gov (United States)

    Zhang, L; Sparreboom, A

    2017-04-01

    Transporters, expressed in various tissues, govern the absorption, distribution, metabolism, and excretion of drugs, and consequently their inherent safety and efficacy profiles. Drugs may interact with a transporter as a substrate and/or an inhibitor. Understanding transporter-mediated drug-drug interactions (DDIs), in addition to enzyme-mediated DDIs, is an integral part of risk assessment in drug development and regulatory review because the concomitant use of more than one medication in patients is common. © 2016 ASCPT.

  10. How cholesterol interacts with proteins and lipids during its intracellular transport

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Solanko, Katarzyna

    2015-01-01

    as well as by non-vesicular sterol exchange between organelles. In this article, we will review recent progress in elucidating sterol-lipid and sterol-protein interactions contributing to proper sterol transport in living cells. We outline recent biophysical models of cholesterol distribution and dynamics...... for characterization of sterol-protein interactions and for monitoring intracellular sterol transport. Finally, we review recent work on the molecular mechanisms underlying lipoprotein-mediated cholesterol import into mammalian cells and describe the process of cellular cholesterol efflux. Overall, we emphasize how......Sterols, as cholesterol in mammalian cells and ergosterol in fungi, are indispensable molecules for proper functioning and nanoscale organization of the plasma membrane. Synthesis, uptake and efflux of cholesterol are regulated by a variety of protein-lipid and protein-protein interactions...

  11. N(1)-methylnicotinamide as an endogenous probe for drug interactions by renal cation transporters: studies on the metformin-trimethoprim interaction.

    Science.gov (United States)

    Müller, Fabian; Pontones, Constanza A; Renner, Bertold; Mieth, Maren; Hoier, Eva; Auge, Daniel; Maas, Renke; Zolk, Oliver; Fromm, Martin F

    2015-01-01

    N(1)-methylnicotinamide (NMN) was proposed as an in vivo probe for drug interactions involving renal cation transporters, which, for example, transport the oral antidiabetic drug metformin, based on a study with the inhibitor pyrimethamine. The role of NMN for predicting other interactions with involvement of renal cation transporters (organic cation transporter 2, OCT2; multidrug and toxin extrusion proteins 1 and 2-K, MATE1 and MATE2-K) is unclear. We determined inhibition of metformin or NMN transport by trimethoprim using cell lines expressing OCT2, MATE1, or MATE2-K. Moreover, a randomized, open-label, two-phase crossover study was performed in 12 healthy volunteers. In each phase, 850 mg metformin hydrochloride was administered p.o. in the evening of day 4 and in the morning of day 5. In phase B, 200 mg trimethoprim was administered additionally p.o. twice daily for 5 days. Metformin pharmacokinetics and effects (measured by OGTT) and NMN pharmacokinetics were determined. Trimethoprim inhibited metformin transport with K i values of 27.2, 6.3, and 28.9 μM and NMN transport with IC50 values of 133.9, 29.1, and 0.61 μM for OCT2, MATE1, and MATE2-K, respectively. In the clinical study, trimethoprim increased metformin area under the plasma concentration-time curve (AUC) by 29.5 % and decreased metformin and NMN renal clearances by 26.4 and 19.9 %, respectively (p ≤ 0.01). Moreover, decreases of NMN and metformin renal clearances due to trimethoprim correlated significantly (r S=0.727, p=0.010). These data on the metformin-trimethoprim interaction support the potential utility of N(1)-methylnicotinamide as an endogenous probe for renal drug-drug interactions with involvement of renal cation transporters.

  12. Transportation dose analysis using an interactive menu-driven computer program

    International Nuclear Information System (INIS)

    Strenge, D.L.; Peloquin, R.A.

    1984-10-01

    An easy-to-use software package is described for performing radiological consequence analyses for transportation scenarios involving truck or rail transport of spent fuel, HLW and other radioactive waste forms. The consequence analysis is based on the unit radiological factors (person-rem/km) developed by the Transportation Technology Center (Sandia National Laboratories). These generic unit radiological factors are combined with user-supplied information describing transporation distances, routes and waste types to estimate total exposure of the population. The software was developed for use in preparing the Environmental Assessment for the Monitored Retrievable Storage Program and is suitable for such analyses as siting waste repositories. The key feature of the software is the user-oriented, menu-driven interactive input mode available as an alternative to formatted input. The interactive input option allows the user to supply all input data, edit the data and run the program. Output reports can be diverted to a high-speed printer

  13. Molecular Determinants for Substrate Interactions with the Glycine Transporter GlyT2.

    Science.gov (United States)

    Carland, Jane E; Thomas, Michael; Mostyn, Shannon N; Subramanian, Nandhitha; O'Mara, Megan L; Ryan, Renae M; Vandenberg, Robert J

    2018-03-21

    Transporters in the SLC6 family play key roles in regulating neurotransmission and are the targets for a wide range of therapeutics. Important insights into the transport mechanisms and the specificity of drug interactions of SLC6 transporters have been obtained from the crystal structures of a bacterial homologue of the family, LeuT Aa , and more recently the Drosophila dopamine transporter and the human serotonin transporter. However, there is disputed evidence that the bacterial leucine transporter, LeuT Aa , contains two substrate binding sites that work cooperatively in the mechanism of transport, with the binding of a second substrate being required for the release of the substrate from the primary site. An alternate proposal is that there may be low affinity binding sites that serve to direct the flow of substrates to the primary site. We have used a combination of molecular dynamics simulations of substrate interactions with a homology model of GlyT2, together with radiolabeled amino acid uptake assays and electrophysiological analysis of wild-type and mutant transporters, to provide evidence that substrate selectivity of GlyT2 is determined entirely by the primary substrate binding site and, furthermore, if a secondary site exists then it is a low affinity nonselective amino acid binding site.

  14. Documentation for TRACE: an interactive beam-transport code

    International Nuclear Information System (INIS)

    Crandall, K.R.; Rusthoi, D.P.

    1985-01-01

    TRACE is an interactive, first-order, beam-dynamics computer program. TRACE includes space-charge forces and mathematical models for a number of beamline elements not commonly found in beam-transport codes, such as permanent-magnet quadrupoles, rf quadrupoles, rf gaps, accelerator columns, and accelerator tanks. TRACE provides an immediate graphic display of calculative results, has a powerful and easy-to-use command procedure, includes eight different types of beam-matching or -fitting capabilities, and contains its own internal HELP package. This report describes the models and equations used for each of the transport elements, the fitting procedures, and the space-charge/emittance calculations, and provides detailed instruction for using the code

  15. PyMercury: Interactive Python for the Mercury Monte Carlo Particle Transport Code

    International Nuclear Information System (INIS)

    Iandola, F.N.; O'Brien, M.J.; Procassini, R.J.

    2010-01-01

    Monte Carlo particle transport applications are often written in low-level languages (C/C++) for optimal performance on clusters and supercomputers. However, this development approach often sacrifices straightforward usability and testing in the interest of fast application performance. To improve usability, some high-performance computing applications employ mixed-language programming with high-level and low-level languages. In this study, we consider the benefits of incorporating an interactive Python interface into a Monte Carlo application. With PyMercury, a new Python extension to the Mercury general-purpose Monte Carlo particle transport code, we improve application usability without diminishing performance. In two case studies, we illustrate how PyMercury improves usability and simplifies testing and validation in a Monte Carlo application. In short, PyMercury demonstrates the value of interactive Python for Monte Carlo particle transport applications. In the future, we expect interactive Python to play an increasingly significant role in Monte Carlo usage and testing.

  16. Interactions of psychosocial factors with built environments in explaining adolescents' active transportation.

    Science.gov (United States)

    Wang, Xiaobo; Conway, Terry L; Cain, Kelli L; Frank, Lawrence D; Saelens, Brian E; Geremia, Carrie; Kerr, Jacqueline; Glanz, Karen; Carlson, Jordan A; Sallis, James F

    2017-07-01

    The present study examined independent and interacting associations of psychosocial and neighborhood built environment variables with adolescents' reported active transportation. Moderating effects of adolescent sex were explored. Mixed-effects regression models were conducted on data from the Teen Environment and Neighborhood observational study (N=928) in the Seattle, WA and Baltimore regions 2009-2011. Frequency index of active transportation to neighborhood destinations (dependent variable) and 7 psychosocial measures were reported by adolescents. Built environment measures included home walkability and count of nearby parks and recreation facilities using GIS procedures and streetscape quality from environmental audits. Results indicated all 3 environmental variables and 3 psychosocial variables (self-efficacy, social support from peers, and enjoyment of physical activity) had significant positive main effects with active transportation (Pstransportation (Pstransportation was found among adolescents with the combination of activity-supportive built environment and positive psychosocial characteristics. Three-way interactions with sex indicated similar associations for girls and boys, with one exception. Results provided modest support for the ecological model principle of interactions across levels, highlight the importance of both built environment and psychosocial factors in shaping adolescents' active transportation, demonstrated the possibility of sex-specific findings, and suggested strategies for improving adolescents' active transportation may be most effective when targeting multiple levels of influence. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Interaction between Polyketide Synthase and Transporter Suggests Coupled Synthesis and Export of Virulence Lipid in M. tuberculosis.

    Directory of Open Access Journals (Sweden)

    2005-09-01

    Full Text Available Virulent mycobacteria utilize surface-exposed polyketides to interact with host cells, but the mechanism by which these hydrophobic molecules are transported across the cell envelope to the surface of the bacteria is poorly understood. Phthiocerol dimycocerosate (PDIM, a surface-exposed polyketide lipid necessary for Mycobacterium tuberculosis virulence, is the product of several polyketide synthases including PpsE. Transport of PDIM requires MmpL7, a member of the MmpL family of RND permeases. Here we show that a domain of MmpL7 biochemically interacts with PpsE, the first report of an interaction between a biosynthetic enzyme and its cognate transporter. Overexpression of the interaction domain of MmpL7 acts as a dominant negative to PDIM synthesis by poisoning the interaction between synthase and transporter. This suggests that MmpL7 acts in complex with the synthesis machinery to efficiently transport PDIM across the cell membrane. Coordination of synthesis and transport may not only be a feature of MmpL-mediated transport in M. tuberculosis, but may also represent a general mechanism of polyketide export in many different microorganisms.

  18. Energy for road passenger transport and sustainable development: assessing policies and goals interactions

    DEFF Research Database (Denmark)

    Meza, Maria Josefina Figueroa; Ribeiro, Suzana Kahn

    2013-01-01

    and sustainable development goals. Essential, uncertain and limited interactions are mapped out as a result, their overview indicates that a full reconciliation between these policies and sustainability goals is not always attainable. The careful alignment and contextual examination of interactions between...... measures and goals as exemplified in this approach can help inform practical transport energy policy that better match an agenda for sustainable development.......Development that is sustainable requires an operational, efficient and safe transportation system fueled by clean, low-carbon, secure and affordable energy. The energy used in road passenger transport enables social and economic development and is the target of interventions to fight pressing urban...

  19. Electroneutrality and ionic interactions in the modeling of mass transport in dilute electrochemical systems

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Swarnavo, E-mail: ss927@cornell.edu [School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14850 (United States); Aquino, Wilkins, E-mail: wa27@cornell.edu [School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14850 (United States)

    2011-10-01

    Highlights: > A simple ionic transport model including Coulombic interactions is proposed. > A connection between electroneutrality and Onsager's cross-flux terms is established. > Interionic flux densities are obtained from a constrained variational statement. > The numerical stiffness of the classical P-N-P system is bypassed using our proposed approach. - Abstract: We propose a simple, but novel mathematical and numerical approach to describe mass transport in dilute solutions, taking into consideration ionic interactions. Our proposed approach treats fluxes due to ionic interactions as additional unknowns in the transport equation. Through variational arguments, we derive a simple expression for these ionic fluxes in terms of the electroneutrality condition, which allows for a straightforward treatment of the new unknowns. Furthermore, a finite element formulation based on our mathematical model is presented. Finally, using the distribution of the interionic flux density and an energy dissipation function, we show that besides properly capturing flow due to ionic interactions, our model can also describe independent ionic flow as predicted by the conventional Nernst-Planck equation in regions where ionic interactions are weak.

  20. Land use transport interaction models: Application perspectives for the city of Thessaloniki

    Directory of Open Access Journals (Sweden)

    Pozoukidou Georgia

    2014-01-01

    Full Text Available Land use patterns and transport system are considered to be the two basic components of the urban development process, and as such they have been in the core of spatial planning policies for the last 4 decades. Land use transport interaction models are computer tools that could help us understand land use changes and organization of human activities in relation to existing or planned transport infrastructure. In this context this paper examines the perspectives of applying a land use transport interaction model for the city of Thessaloniki. Obtaining, preparing and validating socioeconomic data is a crucial part of the modeling process, therefore an extensive search of the required data was performed. The quest for appropriate and suitable data concluded with a detailed recording of emerged problems. In response to the inability of finding suitable data to perform the first step of the modeling process i.e. calibration, the paper concludes with some thoughts related to data availability, organization and standardization issues. Last but not least, the paper stresses out the significance of data availability for utilization of land use transport models, so as not to remain purely academic products but tools with practical value in planning.

  1. The Nucleotide-Free State of the Multidrug Resistance ABC Transporter LmrA: Sulfhydryl Cross-Linking Supports a Constant Contact, Head-to-Tail Configuration of the Nucleotide-Binding Domains.

    Directory of Open Access Journals (Sweden)

    Peter M Jones

    Full Text Available ABC transporters are integral membrane pumps that are responsible for the import or export of a diverse range of molecules across cell membranes. ABC transporters have been implicated in many phenomena of medical importance, including cystic fibrosis and multidrug resistance in humans. The molecular architecture of ABC transporters comprises two transmembrane domains and two ATP-binding cassettes, or nucleotide-binding domains (NBDs, which are highly conserved and contain motifs that are crucial to ATP binding and hydrolysis. Despite the improved clarity of recent structural, biophysical, and biochemical data, the seemingly simple process of ATP binding and hydrolysis remains controversial, with a major unresolved issue being whether the NBD protomers separate during the catalytic cycle. Here chemical cross-linking data is presented for the bacterial ABC multidrug resistance (MDR transporter LmrA. These indicate that in the absence of nucleotide or substrate, the NBDs come into contact to a significant extent, even at 4°C, where ATPase activity is abrogated. The data are clearly not in accord with an inward-closed conformation akin to that observed in a crystal structure of V. cholerae MsbA. Rather, they suggest a head-to-tail configuration 'sandwich' dimer similar to that observed in crystal structures of nucleotide-bound ABC NBDs. We argue the data are more readily reconciled with the notion that the NBDs are in proximity while undergoing intra-domain motions, than with an NBD 'Switch' mechanism in which the NBD monomers separate in between ATP hydrolysis cycles.

  2. Transport with three-particle interaction

    International Nuclear Information System (INIS)

    Morawetz, K.

    2000-01-01

    Starting from a point - like two - and three - particle interaction the kinetic equation is derived. While the drift term of the kinetic equation turns out to be determined by the known Skyrme mean field the collision integral appears in two - and three - particle parts. The cross section results from the same microscopic footing and is naturally density dependent due to the three - particle force. By this way no hybrid model for drift and cross section is needed for nuclear transport. The resulting equation of state has besides the mean field correlation energy also a two - and three - particle correlation energy which both are calculated analytically for the ground state. These energies contribute to the equation of state and lead to an occurrence of a maximum at 3 times nuclear density in the total energy. (author)

  3. Apoptosis-linked Gene-2 (ALG-2)/Sec31 Interactions Regulate Endoplasmic Reticulum (ER)-to-Golgi Transport

    Science.gov (United States)

    Helm, Jared R.; Bentley, Marvin; Thorsen, Kevin D.; Wang, Ting; Foltz, Lauren; Oorschot, Viola; Klumperman, Judith; Hay, Jesse C.

    2014-01-01

    Luminal calcium released from secretory organelles has been suggested to play a regulatory role in vesicle transport at several steps in the secretory pathway; however, its functional roles and effector pathways have not been elucidated. Here we demonstrate for the first time that specific luminal calcium depletion leads to a significant decrease in endoplasmic reticulum (ER)-to-Golgi transport rates in intact cells. Ultrastructural analysis revealed that luminal calcium depletion is accompanied by increased accumulation of intermediate compartment proteins in COPII buds and clusters of unfused COPII vesicles at ER exit sites. Furthermore, we present several lines of evidence suggesting that luminal calcium affected transport at least in part through calcium-dependent interactions between apoptosis-linked gene-2 (ALG-2) and the Sec31A proline-rich region: 1) targeted disruption of ALG-2/Sec31A interactions caused severe defects in ER-to-Golgi transport in intact cells; 2) effects of luminal calcium and ALG-2/Sec31A interactions on transport mutually required each other; and 3) Sec31A function in transport required luminal calcium. Morphological phenotypes of disrupted ALG-2/Sec31A interactions were characterized. We found that ALG-2/Sec31A interactions were not required for the localization of Sec31A to ER exit sites per se but appeared to acutely regulate the stability and trafficking of the cargo receptor p24 and the distribution of the vesicle tether protein p115. These results represent the first outline of a mechanism that connects luminal calcium to specific protein interactions regulating vesicle trafficking machinery. PMID:25006245

  4. Institutional interactions in developing a transportation system under the Nuclear Waste Policy Act

    International Nuclear Information System (INIS)

    Denny, S.H.

    1986-01-01

    The Department of Energy (DOE) recognizes that the success of its efforts to develop and operate a system for transporting nuclear waste under the provisions of the Nuclear Waste Policy Act of 1982 (NWPA) depends in large measure on the effectiveness of Departmental interactions with the affected parties. To ensure the necessary network of communication, the DOE is establishing lines of contact with those who are potential participants in the task of developing the policies and procedures for the NWPA transportation system. In addition, a number of measures have been initiated to reinforce broad-based involvement in program development. The Transportation Institutional Plan provides a preliminary road map of DOE's projected interactions over the next decade and is discussed in this paper

  5. The effect of electron-electron interaction induced dephasing on electronic transport in graphene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Kahnoj, Sina Soleimani; Touski, Shoeib Babaee [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Pourfath, Mahdi, E-mail: pourfath@ut.ac.ir, E-mail: pourfath@iue.tuwien.ac.at [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Institute for Microelectronics, TU Wien, Gusshausstrasse 27–29/E360, 1040 Vienna (Austria)

    2014-09-08

    The effect of dephasing induced by electron-electron interaction on electronic transport in graphene nanoribbons is theoretically investigated. In the presence of disorder in graphene nanoribbons, wavefunction of electrons can set up standing waves along the channel and the conductance exponentially decreases with the ribbon's length. Employing the non-equilibrium Green's function formalism along with an accurate model for describing the dephasing induced by electron-electron interaction, we show that this kind of interaction prevents localization and transport of electrons remains in the diffusive regime where the conductance is inversely proportional to the ribbon's length.

  6. Interaction between sheared flows and turbulent transport in magnetized fusion-grade plasmas; Interaction entre ecoulements cisailles et transport turbulent dans les plasmas de fusion magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Leconte, M.

    2008-11-15

    The H confinement regime is set when the heating power reaches a threshold value P{sub c} and is linked to the formation of a transport barrier in the edge region of the plasma. Such a barrier is characterized by a high pressure gradient and is submitted to ELM (edge localized mode) instabilities. ELM instabilities trigger violent quasi-periodical ejections of matter and heat that induce quasi-periodical relaxations of the transport barrier called relaxation oscillations. In this work we studied the interaction between sheared flows and turbulence in fusion plasmas. In particular, we studied the complex dynamics of a transport barrier and we show through a simulation that resonant magnetic perturbations could control relaxation oscillations without a significant loss of confinement

  7. Transport of an interacting Bose gas in 1D disordered lattices

    Energy Technology Data Exchange (ETDEWEB)

    D' Errico, C.; Chaudhuri, S.; Gori, L.; Kumar, A.; Lucioni, E.; Tanzi, L.; Inguscio, M.; Modugno, G. [LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, and CNR-INO, 50019 Sesto Fiorentino (Italy)

    2014-08-20

    We use ultracold atoms in a quasiperiodic lattice to study two outstanding problems in the physics of disordered systems: a) the anomalous diffusion of a wavepacket in the presence of disorder, interactions and noise; b) the transport of a disordered superfluid. a) Our results show that the subdiffusion, observed when interaction alone is present, can be modelled with a nonlinear diffusion equation and the peculiar shape of the expanding density profiles can be connected to the microscopic nonlinear diffusion coefficients. Also when noise alone is present we can describe the observed normal diffusion dynamics by existing microscopic models. In the unexplored regime in which noise and interaction are combined, instead, we observe an anomalous diffusion, that we model with a generalized diffusion equation, where noise- and interaction-induced contributions add each other. b) We find that an instability appearing at relatively large momenta can be employed to locate the fluid-insulator crossover driven by disorder. By investigating the momentum-dependent transport, we observe a sharp crossover from a weakly dissipative regime to a strongly unstable one at a disorder-dependent critical momentum. The set of critical disorder and interaction strengths for which such critical momentum vanishes, can be identified with the separation between a fluid regime and an insulating one and can be related to the predicted zero-temperature superfluid-Bose glass transition.

  8. Transport of an interacting Bose gas in 1D disordered lattices

    International Nuclear Information System (INIS)

    D'Errico, C.; Chaudhuri, S.; Gori, L.; Kumar, A.; Lucioni, E.; Tanzi, L.; Inguscio, M.; Modugno, G.

    2014-01-01

    We use ultracold atoms in a quasiperiodic lattice to study two outstanding problems in the physics of disordered systems: a) the anomalous diffusion of a wavepacket in the presence of disorder, interactions and noise; b) the transport of a disordered superfluid. a) Our results show that the subdiffusion, observed when interaction alone is present, can be modelled with a nonlinear diffusion equation and the peculiar shape of the expanding density profiles can be connected to the microscopic nonlinear diffusion coefficients. Also when noise alone is present we can describe the observed normal diffusion dynamics by existing microscopic models. In the unexplored regime in which noise and interaction are combined, instead, we observe an anomalous diffusion, that we model with a generalized diffusion equation, where noise- and interaction-induced contributions add each other. b) We find that an instability appearing at relatively large momenta can be employed to locate the fluid-insulator crossover driven by disorder. By investigating the momentum-dependent transport, we observe a sharp crossover from a weakly dissipative regime to a strongly unstable one at a disorder-dependent critical momentum. The set of critical disorder and interaction strengths for which such critical momentum vanishes, can be identified with the separation between a fluid regime and an insulating one and can be related to the predicted zero-temperature superfluid-Bose glass transition

  9. Caenorhabditis elegans ABCRNAi transporters interact genetically with rde-2 and mut-7.

    Science.gov (United States)

    Sundaram, Prema; Han, Wang; Cohen, Nancy; Echalier, Benjamin; Albin, John; Timmons, Lisa

    2008-02-01

    RNA interference (RNAi) mechanisms are conserved and consist of an interrelated network of activities that not only respond to exogenous dsRNA, but also perform endogenous functions required in the fine tuning of gene expression and in maintaining genome integrity. Not surprisingly, RNAi functions have widespread influences on cellular function and organismal development. Previously, we observed a reduced capacity to mount an RNAi response in nine Caenorhabditis elegans mutants that are defective in ABC transporter genes (ABC(RNAi) mutants). Here, we report an exhaustive study of mutants, collectively defective in 49 different ABC transporter genes, that allowed for the categorization of one additional transporter into the ABC(RNAi) gene class. Genetic complementation tests reveal functions for ABC(RNAi) transporters in the mut-7/rde-2 branch of the RNAi pathway. These second-site noncomplementation interactions suggest that ABC(RNAi) proteins and MUT-7/RDE-2 function together in parallel pathways and/or as multiprotein complexes. Like mut-7 and rde-2, some ABC(RNAi) mutants display transposon silencing defects. Finally, our analyses reveal a genetic interaction network of ABC(RNAi) gene function with respect to this part of the RNAi pathway. From our results, we speculate that the coordinated activities of ABC(RNAi) transporters, through their effects on endogenous RNAi-related mechanisms, ultimately affect chromosome function and integrity.

  10. Cosmic-Ray Transport in Heliospheric Magnetic Structures. II. Modeling Particle Transport through Corotating Interaction Regions

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Andreas [Université Libre de Bruxelles, Service de Physique Statistique et des Plasmas, CP 231, B-1050 Brussels (Belgium); Wiengarten, Tobias; Fichtner, Horst [Institut für Theoretische Physik IV, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Effenberger, Frederic [Department of Physics and KIPAC, Stanford University, Stanford, CA 94305 (United States); Kühl, Patrick; Heber, Bernd [Institut für Experimentelle und Angewandte Physik, Christian-Albrecht-Universität zu Kiel, D-24098 Kiel (Germany); Raath, Jan-Louis; Potgieter, Marius S. [Centre for Space Research, North-West University, 2520 Potchefstroom (South Africa)

    2017-03-01

    The transport of cosmic rays (CRs) in the heliosphere is determined by the properties of the solar wind plasma. The heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric CR transport are structures such as corotating interaction regions (CIRs), which, due to the enhancement of the magnetic field strength and magnetic fluctuations within and due to the associated shocks as well as stream interfaces, do influence the CR diffusion and drift. In a three-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with the numerical magnetohydrodynamic (MHD) framework Cronos (Wiengarten et al., referred as Paper I), and the results serve as input to a transport code employing a stochastic differential equation approach (this paper). While, in Paper I, we presented results from 3D simulations with Cronos, the MHD output is now taken as an input to the CR transport modeling. We discuss the diffusion and drift behavior of Galactic cosmic rays using the example of different theories, and study the effects of CIRs on these transport processes. In particular, we point out the wide range of possible particle fluxes at a given point in space resulting from these different theories. The restriction of this variety by fitting the numerical results to spacecraft data will be the subject of the third paper of this series.

  11. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Sourav, E-mail: sourav.bhattacharjee@wur.nl [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Opstal, Edward J. van; Alink, Gerrit M. [Wageningen University, Division of Toxicology (Netherlands); Marcelis, Antonius T. M.; Zuilhof, Han [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Rietjens, Ivonne M. C. M. [Wageningen University, Division of Toxicology (Netherlands)

    2013-06-15

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size {approx}45 nm) and polystyrene nanoparticles (PSNPs/size {approx}50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  12. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Science.gov (United States)

    Bhattacharjee, Sourav; van Opstal, Edward J.; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

    2013-06-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size 45 nm) and polystyrene nanoparticles (PSNPs/size 50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  13. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    International Nuclear Information System (INIS)

    Bhattacharjee, Sourav; Opstal, Edward J. van; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

    2013-01-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size ∼45 nm) and polystyrene nanoparticles (PSNPs/size ∼50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  14. Molecular analysis of interactions between dendrimers and asymmetric membranes at different transport stages.

    Science.gov (United States)

    He, XiaoCong; Qu, ZhiGuo; Xu, Feng; Lin, Min; Wang, JiuLing; Shi, XingHua; Lu, TianJian

    2014-01-07

    Studying dendrimer-biomembrane interactions is important for understanding drug and gene delivery. In this study, coarse-grained molecular dynamics simulations were performed to investigate the behaviors of polyamidoamine (PAMAM) dendrimers (G4 and G5) as they interacted with asymmetric membranes from different sides of the bilayer, thus mimicking different dendrimer transport stages. The G4 dendrimer could insert into the membrane during an equilibrated state, and the G5 dendrimer could induce pore formation in the membrane when the dendrimers interacted with the outer side (outer interactions) of an asymmetric membrane [with 10% dipalmitoyl phosphatidylserine (DPPS) in the inner leaflet of the membrane]. During the interaction with the inner side of the asymmetric membrane (inner interactions), the G4 and G5 dendrimers only adsorbed onto the membrane. As the membrane asymmetry increased (e.g., increased DPPS percentage in the inner leaflet of the membrane), the G4 and G5 dendrimers penetrated deeper into the membrane during the outer interactions and the G4 and G5 dendrimers were adsorbed more tightly onto the membrane for the inner interactions. When the DPPS content reached 50%, the G4 dendrimer could completely penetrate through the membrane from the outer side to the inner side. Our study provides molecular understanding and reference information about different dendrimer transport stages during drug and gene delivery.

  15. Phonon-magnon interaction in low dimensional quantum magnets observed by dynamic heat transport measurements.

    Science.gov (United States)

    Montagnese, Matteo; Otter, Marian; Zotos, Xenophon; Fishman, Dmitry A; Hlubek, Nikolai; Mityashkin, Oleg; Hess, Christian; Saint-Martin, Romuald; Singh, Surjeet; Revcolevschi, Alexandre; van Loosdrecht, Paul H M

    2013-04-05

    Thirty-five years ago, Sanders and Walton [Phys. Rev. B 15, 1489 (1977)] proposed a method to measure the phonon-magnon interaction in antiferromagnets through thermal transport which so far has not been verified experimentally. We show that a dynamical variant of this approach allows direct extraction of the phonon-magnon equilibration time, yielding 400 μs for the cuprate spin-ladder system Ca(9)La(5)Cu(24)O(41). The present work provides a general method to directly address the spin-phonon interaction by means of dynamical transport experiments.

  16. Coupled-resonator waveguide perfect transport single-photon by interatomic dipole-dipole interaction

    Science.gov (United States)

    Yan, Guo-an; Lu, Hua; Qiao, Hao-xue; Chen, Ai-xi; Wu, Wan-qing

    2018-06-01

    We theoretically investigate single-photon coherent transport in a one-dimensional coupled-resonator waveguide coupled to two quantum emitters with dipole-dipole interactions. The numerical simulations demonstrate that the transmission spectrum of the photon depends on the two atoms dipole-dipole interactions and the photon-atom couplings. The dipole-dipole interactions may change the dip positions in the spectra and the coupling strength may broaden the frequency band width in the transmission spectrum. We further demonstrate that the typical transmission spectra split into two dips due to the dipole-dipole interactions. This phenomenon may be used to manufacture new quantum waveguide devices.

  17. Interactions between Radial Electric Field, Transport and Structure in Helical Plasmas

    International Nuclear Information System (INIS)

    Ida, Katsumi and others

    2006-01-01

    Control of the radial electric field is considered to be important in helical plasmas, because the radial electric field and its shear are expected to reduce neoclassical and anomalous transport, respectively. Particle and heat transport, that determines the radial structure of density and electron profiles, sensitive to the structure of radial electric field. On the other hand, the radial electric field itself is determined by the plasma parameters. In general, the sign of the radial electric field is determined by the plasma collisionality, while the magnitude of the radial electric field is determined by the temperature and/or density gradients. Therefore the structure of radial electric field and temperature and density are strongly coupled through the particle and heat transport and formation mechanism of radial electric field. Interactions between radial electric field, transport and structure in helical plasmas is discussed based on the experiments on Large Helical Device

  18. Edge-core interaction revealed with dynamic transport experiment in LHD

    International Nuclear Information System (INIS)

    Tamura, N.; Ida, K.; Inagaki, S.

    2010-11-01

    Large scale coherent structures in electron heat transport of both core and edge plasmas are clearly found in plasma with a nonlocal transport phenomenon (NTP, a core electron temperature rise in response to an edge cooling) on Large Helical Device (LHD). At the onset of the NTP, a first order transition of the electron heat transport, which is characterized by a discontinuity of electron temperature gradient, is found to take place over a wide region (at least 6 cm wide) in the periphery of the plasma. At about the same time, over a wide region (about 10 cm wide) of the plasma core, a second order transition of the electron heat transport, which is characterized by a discontinuity of the time derivative of the electron temperature gradient, appears. The both large scale coherent structures are of a scale larger than a typical micro-turbulent eddy size (a few mm in this case). In order to assess dynamic characteristics of the electron heat transport state in the core region during the NTP, a transit time distribution analysis is applied to the temporal behaviors of the electron temperature gradient. The analysis results more clearly show the existence of the large coherent structures in electron heat transport. Thus the NTP observed in LHD is considered to be invoked by the interaction of those structures. (author)

  19. Plasma Interactions with Mixed Materials and Impurity Transport

    Energy Technology Data Exchange (ETDEWEB)

    Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Beiersdorfer, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chernov, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Frolov, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Magee, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rudd, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Umansky, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-28

    The project brings together three discipline areas at LLNL to develop advanced capability to predict the impact of plasma/material interactions (PMI) on metallic surfaces in magnetic fusion energy (MFE) devices. These areas are (1) modeling transport of wall impurity ions through the edge plasma to the core plasma, (2) construction of a laser blow-off (LBO) system for injecting precise amounts of metallic atoms into a tokamak plasma, and (3) material science analysis of fundamental processes that modify metallic surfaces during plasma bombardment. The focus is on tungsten (W), which is being used for the ITER divertor and in designs of future MFE devices. In area (1), we have worked with the University of California, San Diego (UCSD) on applications of the UEDGE/DUSTT coupled codes to predict the influx of impurity ions from W dust through the edge plasma, including periodic edge-plasma oscillations, and revived a parallel version of UEDGE to speed up these simulations. In addition, the impurity transport model in the 2D UEDGE code has been implemented into the 3D BOUT++ turbulence/transport code to allow fundamental analysis of the impact of strong plasma turbulence on the impurity transport. In area (2), construction and testing of the LBO injection system has been completed. The original plan to install the LBO on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton and its use to validate the impurity transport simulations is delayed owing to NSTX-U being offline for substantial magnetic coil repair period. In area (3), an analytic model has been developed to explain the growth of W tendrils (or fuzz) observed for helium-containing plasmas. Molecular dynamics calculations of W sputtering by W and deuterium (D) ions shows that a spatial blending of interatomic potentials is needed to describe the near-surface and deeper regions of the material.

  20. Plasma Interactions with Mixed Materials and Impurity Transport

    International Nuclear Information System (INIS)

    Rognlien, T. D.; Beiersdorfer, Peter; Chernov, A.; Frolov, T.; Magee, E.; Rudd, R.; Umansky, M.

    2016-01-01

    The project brings together three discipline areas at LLNL to develop advanced capability to predict the impact of plasma/material interactions (PMI) on metallic surfaces in magnetic fusion energy (MFE) devices. These areas are (1) modeling transport of wall impurity ions through the edge plasma to the core plasma, (2) construction of a laser blow-off (LBO) system for injecting precise amounts of metallic atoms into a tokamak plasma, and (3) material science analysis of fundamental processes that modify metallic surfaces during plasma bombardment. The focus is on tungsten (W), which is being used for the ITER divertor and in designs of future MFE devices. In area (1), we have worked with the University of California, San Diego (UCSD) on applications of the UEDGE/DUSTT coupled codes to predict the influx of impurity ions from W dust through the edge plasma, including periodic edge-plasma oscillations, and revived a parallel version of UEDGE to speed up these simulations. In addition, the impurity transport model in the 2D UEDGE code has been implemented into the 3D BOUT++ turbulence/transport code to allow fundamental analysis of the impact of strong plasma turbulence on the impurity transport. In area (2), construction and testing of the LBO injection system has been completed. The original plan to install the LBO on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton and its use to validate the impurity transport simulations is delayed owing to NSTX-U being offline for substantial magnetic coil repair period. In area (3), an analytic model has been developed to explain the growth of W tendrils (or fuzz) observed for helium-containing plasmas. Molecular dynamics calculations of W sputtering by W and deuterium (D) ions shows that a spatial blending of interatomic potentials is needed to describe the near-surface and deeper regions of the material.

  1. Hepatic transporter drug-drug interactions: an evaluation of approaches and methodologies.

    Science.gov (United States)

    Williamson, Beth; Riley, Robert J

    2017-12-01

    Drug-drug interactions (DDIs) continue to account for 5% of hospital admissions and therefore remain a major regulatory concern. Effective, quantitative prediction of DDIs will reduce unexpected clinical findings and encourage projects to frontload DDI investigations rather than concentrating on risk management ('manage the baggage') later in drug development. A key challenge in DDI prediction is the discrepancies between reported models. Areas covered: The current synopsis focuses on four recent influential publications on hepatic drug transporter DDIs using static models that tackle interactions with individual transporters and in combination with other drug transporters and metabolising enzymes. These models vary in their assumptions (including input parameters), transparency, reproducibility and complexity. In this review, these facets are compared and contrasted with recommendations made as to their application. Expert opinion: Over the past decade, static models have evolved from simple [I]/k i models to incorporate victim and perpetrator disposition mechanisms including the absorption rate constant, the fraction of the drug metabolised/eliminated and/or clearance concepts. Nonetheless, models that comprise additional parameters and complexity do not necessarily out-perform simpler models with fewer inputs. Further, consideration of the property space to exploit some drug target classes has also highlighted the fine balance required between frontloading and back-loading studies to design out or 'manage the baggage'.

  2. Coherent transport through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hiltscher, Bastian

    2012-10-05

    The present thesis is composed of four different works. All deal with coherent transport through interacting quantum dots, which are tunnel-coupled to external leads. There a two main motivations for the use of quantum dots. First, they are an ideal device to study the influence of strong Coulomb repulsion, and second, their discrete energy levels can easily be tuned by external gate electrodes to create different transport regimes. The expression of coherence includes a very wide range of physical correlations and, therefore, the four works are basically independent of each other. Before motivating and introducing the different works in more detail, we remark that in all works a diagrammatic real-time perturbation theory is used. The fermionic degrees of freedom of the leads are traced out and the elements of the resulting reduced density matrix can be treated explicitly by means of a generalized master equation. How this equation is solved, depends on the details of the problem under consideration. In the first of the four works adiabatic pumping through an Aharonov-Bohm interferometer with a quantum dot embedded in each of the two arms is studied. In adiabatic pumping transport is generated by varying two system parameters periodically in time. We consider the two dot levels to be these two pumping parameters. Since they are located in different arms of the interferometer, pumping is a quantum mechanical effect purely relying on coherent superpositions of the dot states. It is very challenging to identify a quantum pumping mechanism in experiments, because a capacitive coupling of the gate electrodes to the leads may yield an undesired AC bias voltage, which is rectified by a time dependent conductance. Therefore, distinguishing features of these two transport mechanisms are required. We find that the dependence on the magnetic field is the key feature. While the pumped charge is an odd function of the magnetic flux, the rectified current is even, at least in

  3. Coherent transport through interacting quantum dots

    International Nuclear Information System (INIS)

    Hiltscher, Bastian

    2012-01-01

    The present thesis is composed of four different works. All deal with coherent transport through interacting quantum dots, which are tunnel-coupled to external leads. There a two main motivations for the use of quantum dots. First, they are an ideal device to study the influence of strong Coulomb repulsion, and second, their discrete energy levels can easily be tuned by external gate electrodes to create different transport regimes. The expression of coherence includes a very wide range of physical correlations and, therefore, the four works are basically independent of each other. Before motivating and introducing the different works in more detail, we remark that in all works a diagrammatic real-time perturbation theory is used. The fermionic degrees of freedom of the leads are traced out and the elements of the resulting reduced density matrix can be treated explicitly by means of a generalized master equation. How this equation is solved, depends on the details of the problem under consideration. In the first of the four works adiabatic pumping through an Aharonov-Bohm interferometer with a quantum dot embedded in each of the two arms is studied. In adiabatic pumping transport is generated by varying two system parameters periodically in time. We consider the two dot levels to be these two pumping parameters. Since they are located in different arms of the interferometer, pumping is a quantum mechanical effect purely relying on coherent superpositions of the dot states. It is very challenging to identify a quantum pumping mechanism in experiments, because a capacitive coupling of the gate electrodes to the leads may yield an undesired AC bias voltage, which is rectified by a time dependent conductance. Therefore, distinguishing features of these two transport mechanisms are required. We find that the dependence on the magnetic field is the key feature. While the pumped charge is an odd function of the magnetic flux, the rectified current is even, at least in

  4. Effective interactions, transport properties, and elementary excitations in helium three-helium four mixtures

    International Nuclear Information System (INIS)

    Hsu, W.

    1984-01-01

    A unified theory of effective interaction, elementary excitations, transport properties, and possible superfluidity of 3 He- 4 He mixtures was developed. The basic approach is patterned after that of Aldrich and Pines (AP) for pure 4 He and 3 He, in which the consequence of the strong interactions in 3 He and 4 He is described in terms of self-consistent fields. The strength of these fields are determined by physical arguments, static measurement, and sum rule considerations. A set of pseudopotentials was developed to describe the 3 He- 3 He and 3 He- 4 He interactions. In the long wavelength and zero concentration limit, these potentials are obtained by the thermodynamic argument of Bardeen, Baym, and Pines. At finite concentration and finite momentum transfer, these potentials are obtained with the aids of a scaling law and the AP pseudopotential theory. From these pseudopotentials, the scattering amplitudes, transport coefficients, and normal-superfluid transition temperature are calculated as functions of 3 He concentration. Good agreement is obtained between theory and experiment for low temperature transport coefficients, and the 3 He superfluid transition temperature is predicted to be approx. -80 K. The change in the density fluctuation excitation spectrum of 4 He atoms in 3 He- 4 He mixtures is calculated

  5. Interaction of Degradation, Deformation and Transport Processes in Municipal Solid Waste Landfills

    OpenAIRE

    Bente, Sonja

    2010-01-01

    In this thesis a model for the complex interactions between deformation, degradation and transport processe in municipal solid waste landfills is presented. Key aspects of the model are a joint continuum mechanical framework and a monolithic solution of the governing equations within the Theory of Porous Media. Interactions are considered by coupling the governing physical fields over the domain of a representative elementary volume via selected state variables. A simplified two-stage degrada...

  6. Discrete and continuum links to a nonlinear coupled transport problem of interacting populations

    Science.gov (United States)

    Duong, M. H.; Muntean, A.; Richardson, O. M.

    2017-07-01

    We are interested in exploring interacting particle systems that can be seen as microscopic models for a particular structure of coupled transport flux arising when different populations are jointly evolving. The scenarios we have in mind are inspired by the dynamics of pedestrian flows in open spaces and are intimately connected to cross-diffusion and thermo-diffusion problems holding a variational structure. The tools we use include a suitable structure of the relative entropy controlling TV-norms, the construction of Lyapunov functionals and particular closed-form solutions to nonlinear transport equations, a hydrodynamics limiting procedure due to Philipowski, as well as the construction of numerical approximates to both the continuum limit problem in 2D and to the original interacting particle systems.

  7. The cannabinoid transporter inhibitor OMDM-2 reduces social interaction: Further evidence for transporter-mediated endocannabinoid release.

    Science.gov (United States)

    Seillier, Alexandre; Giuffrida, Andrea

    2018-03-01

    Experimental evidence suggests that the transport of endocannabinoids might work bi-directionally. Accordingly, it is possible that pharmacological blockade of the latter affects not only the re-uptake, but also the release of endocannabinoids, thus preventing them from stimulating CB 1 receptors. We used biochemical, pharmacological, and behavioral approaches to investigate the effects of the transporter inhibitor OMDM-2 on social interaction, a behavioral assay that requires activation of CB 1 receptors. The underlying mechanisms of OMDM-2 were compared with those of the Fatty Acid Amide Hydrolase (FAAH) inhibitor URB597. Systemic administration of OMDM-2 reduced social interaction, but in contrast to URB597-induced social deficit, this effect was not reversed by the TRPV1 antagonist capsazepine. The CB 1 antagonist AM251, which did not affect URB597-induced social withdrawal, exacerbated OMDM-2 effect. In addition, the potent CB 1 agonist CP55,940 reversed OMDM-2-, but not URB597-, induced social withdrawal. Blockade of CB 1 receptor by AM251 reduced social interaction and the cholecystokinin CCK2 antagonist LY225910 reversed this effect. Similarly, OMDM-2-induced social withdrawal was reversed by LY225910, whereas URB597 effect was not. Elevation of endocannabinoid levels by URB597 or JZL184, an inhibitor of 2-AG degradation, failed to reverse OMDM-2-induced social withdrawal, and did not show additive effects on cannabinoid measurements when co-administered with OMDM-2. Taken together, these findings indicate that OMDM-2 impaired social interaction in a manner that is consistent with reduced activation of presynaptic CB 1 receptors. As cannabinoid reuptake inhibitors may impair endocannabinoid release, caution should be taken when using these drugs to enhance endocannabinoid tone in vivo. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Interaction of Drug or Food with Drug Transporters in Intestine and Liver.

    Science.gov (United States)

    Nakanishi, Takeo; Tamai, Ikumi

    2015-01-01

    Oral bioavailability (F) is determined as fraction of the drug dose absorbed through the gastrointestinal membranes (Fa), the unmetabolized fraction of the absorbed dose that passes through the gut into the portal blood (Fg), and the hepatic first pass availability (Fh), namely F is expressed as the product of Fa, Fg and Fh (F = Fa.Fg.Fh). Current evidence suggests that transporter proteins play a role in intestinal absorption and hepatobiliary clearance of drugs. Among those transporters, this review will focus on PEPT1 and OATP2B1 as influx transporter and p-glycoprotein (P-gp) and BCRP as efflux transporter in intestinal epithelial cells, and on OATP1B1 and 1B3 as influx transporter and MRP2 as efflux transporter in hepatocytes, respectively, because drug-drug (DDI) and -food (DFI) interactions on these transporter are considered to affect bioavailability of their substrate drugs. DDI and DFI may reduce systemic exposure to drug by blocking influx transporters in intestine, but increase it by modulating influx and efflux transporters in liver and efflux transporters in intestines. Namely, drug disposition and efficacy are likely affected by DDI and DFI, resulting in treatment failures or increase in adverse effect. Therefore, it is of significantly importance to understand precise mechanism of DDI and DFI. This review will present information about transporter-based DDI and DFI in the processes of intestinal absorption and hepatic clearance of drugs, and discuss about their clinical implication.

  9. Simultaneous Assessment of Transporter-Mediated Drug-Drug Interactions Using a Probe Drug Cocktail in Cynomolgus Monkey.

    Science.gov (United States)

    Kosa, Rachel E; Lazzaro, Sarah; Bi, Yi-An; Tierney, Brendan; Gates, Dana; Modi, Sweta; Costales, Chester; Rodrigues, A David; Tremaine, Larry M; Varma, Manthena V

    2018-06-07

    We aim to establish an in vivo preclinical model to enable simultaneous assessment of inhibition potential of an investigational drug on clinically relevant drug transporters, organic anion transporting polypeptide (OATP)1B, breast cancer resistance protein (BCRP), P-glycoprotein (P-gp) and organic anion transporter (OAT)3. Pharmacokinetics of substrate cocktail consisting of pitavastatin (OATP1B substrate), rosuvastatin (OATP1B/BCRP/OAT3), sulfasalazine (BCRP) and talinolol (P-gp) were obtained in cynomolgus monkey - alone or in combination with transporter inhibitors. Single dose rifampicin (30 mg/kg) significantly (pdrugs, with a marked effect on pitavastatin and rosuvastatin (AUC ratio ~21-39). Elacridar, BCRP/P-gp inhibitor, increased the AUC of sulfasalazine, talinolol, as well as rosuvastatin and pitavastatin. An OAT1/3 inhibitor (probenecid) significantly (pdrug-drug interaction risk assessment, before advancing a new molecular entity into clinical development, as well as providing mechanistic insights on transporter-mediated interactions. The American Society for Pharmacology and Experimental Therapeutics.

  10. Influence of the flip-flop interaction on a single plasmon transport in 1D waveguide

    Science.gov (United States)

    Ko, Myong-Chol; Kim, Nam-Chol; Ho, Nam-Chol; Ryom, Ju-Song; Hao, Zhong-Hua; Li, Jian-Bo; Wang, Qu-Quan

    2017-12-01

    Transport of a single plasmon in the 1D waveguide coupled to two emitters with the flip-flop interaction is discussed theoretically via the real-space approach. We showed that the transmission and reflection of a single plasmon could be changeable by adjusting the flip-flop coupling strength of the QDs, the interaction of QDs with the metallic nanowaveguide, interparticle distance of the QDs and detuning. Setting the interparticle distances properly results in the switching between the complete transmission and the complete reflection. Especially, our results show that the QDs with the flip-flop interaction play important role in the transport of the propagating single plasmon, which is relevant to the Förster resonance energy transfer from donor QD to acceptor QD.

  11. Interactive 4D Visualization of Sediment Transport Models

    Science.gov (United States)

    Butkiewicz, T.; Englert, C. M.

    2013-12-01

    Coastal sediment transport models simulate the effects that waves, currents, and tides have on near-shore bathymetry and features such as beaches and barrier islands. Understanding these dynamic processes is integral to the study of coastline stability, beach erosion, and environmental contamination. Furthermore, analyzing the results of these simulations is a critical task in the design, placement, and engineering of coastal structures such as seawalls, jetties, support pilings for wind turbines, etc. Despite the importance of these models, there is a lack of available visualization software that allows users to explore and perform analysis on these datasets in an intuitive and effective manner. Existing visualization interfaces for these datasets often present only one variable at a time, using two dimensional plan or cross-sectional views. These visual restrictions limit the ability to observe the contents in the proper overall context, both in spatial and multi-dimensional terms. To improve upon these limitations, we use 3D rendering and particle system based illustration techniques to show water column/flow data across all depths simultaneously. We can also encode multiple variables across different perceptual channels (color, texture, motion, etc.) to enrich surfaces with multi-dimensional information. Interactive tools are provided, which can be used to explore the dataset and find regions-of-interest for further investigation. Our visualization package provides an intuitive 4D (3D, time-varying) visualization of sediment transport model output. In addition, we are also integrating real world observations with the simulated data to support analysis of the impact from major sediment transport events. In particular, we have been focusing on the effects of Superstorm Sandy on the Redbird Artificial Reef Site, offshore of Delaware Bay. Based on our pre- and post-storm high-resolution sonar surveys, there has significant scour and bedform migration around the

  12. Research on the Design of Visually Impaired Interactive Accessibility in Large Urban Public Transport System

    Science.gov (United States)

    Zhang, Weiru

    2017-12-01

    In medieval times, due to people’s reliance on belief, public space of Christianity came into being. With the rise of secularization, religion gradually turned into private belief, and accordingly public space returned to private space. In the 21st century, due to people’s reliance on intelligent devices, information-interactive public space emerges, and as information interaction is constantly constraining the visually impaired, public space regressed to the exclusive space of limited people[1]. Modernity is marked by technical rationality, but an ensuing basic problem lies in the separation between human action, ethics and public space. When technology fails to overcome obstacles for a particular group, the gap between the burgeoning intelligent phenomena and the increasing ratio of visually impaired is also expanding, ultimately resulting in a growing number of “blind spots” in information-interactive space. Technological innovation not only promotes the development of the information industry, but also promotes the rapid development of the transportation industry. Traffic patterns are diversifying and diverging nowadays, but it’s a fatal blow for people with visually disabilities, Because they still can only experience the most traditional mode of transportation, sometimes even not go out. How to guarantee their interactive accessibility in large urban public transport system right, currently, is a very important research direction.

  13. Metabolite transport and associated sugar signalling systems underpinning source/sink interactions.

    Science.gov (United States)

    Griffiths, Cara A; Paul, Matthew J; Foyer, Christine H

    2016-10-01

    Metabolite transport between organelles, cells and source and sink tissues not only enables pathway co-ordination but it also facilitates whole plant communication, particularly in the transmission of information concerning resource availability. Carbon assimilation is co-ordinated with nitrogen assimilation to ensure that the building blocks of biomass production, amino acids and carbon skeletons, are available at the required amounts and stoichiometry, with associated transport processes making certain that these essential resources are transported from their sites of synthesis to those of utilisation. Of the many possible posttranslational mechanisms that might participate in efficient co-ordination of metabolism and transport only reversible thiol-disulphide exchange mechanisms have been described in detail. Sucrose and trehalose metabolism are intertwined in the signalling hub that ensures appropriate resource allocation to drive growth and development under optimal and stress conditions, with trehalose-6-phosphate acting as an important signal for sucrose availability. The formidable suite of plant metabolite transporters provides enormous flexibility and adaptability in inter-pathway coordination and source-sink interactions. Focussing on the carbon metabolism network, we highlight the functions of different transporter families, and the important of thioredoxins in the metabolic dialogue between source and sink tissues. In addition, we address how these systems can be tailored for crop improvement. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Feasibility Study of Increasing Multimodal Interaction between Private and Public Transport Based on the Use of Intellectual Transport Systems and Services

    Directory of Open Access Journals (Sweden)

    Ulrich Weidmann

    2011-04-01

    Full Text Available The introduction of intellectual transport systems and services (ITS into the public and private transport sectors is closely connected with the development of multimodality in transport system (particularly, in towns and their suburbs. Taking into consideration the problems of traffic jams, the need for increasing the efficiency of power consumption and reducing the amount of burnt gases ejected into the air and the harmful effect of noise, the use of multimodal transport concept has been growing fast recently in most cities. It embraces a system of integrated tickets, the infrastructure, allowing a passenger to leave a car or a bike near a public transport station and to continue his/her travel by public transport (referred to as ‘Park&Ride’, ‘Bike&Ride’, as well as, real-time information system, universal design, and computer-aided traffic control. These concepts seem to be even more effective, when multimodal intellectual transport systems and services (ITS are introduced. In Lithuania, ITS is not widely used in passenger transportation, though its potential is great, particularly, taking into consideration the critical state of the capacity of public transport infrastructure. The paper considers the possibilities of increasing the effectiveness of public transport system ITS by increasing its interaction with private transport in the context of multimodal concept realization.Article in Lithuanian

  15. Effective interactions, elementary excitations, and transport in the helium liquids

    International Nuclear Information System (INIS)

    Pines, D.

    1986-01-01

    Polarization potentials, the self-consistent fields which describe the primary consequences of the strong atom-atom interaction in the helium liquids, are developed for liquid 4 He and 3 He. Emphasis is placed on the common physical origin of the effective interactions in all helium liquids, and the hierarchy of physical effects (very short-range atomic correlations, zero point motion, and the Pauli principle) which determine their strength is reviewed. An overview is then given of the application of polarization potential theory to experiment, including the phonon-maxon-roton spectra of 4 He and 3 He- 4 He mixtures, the phonon-maxon spectrum of normal and spin-polarized 3 He, and the transport properties of superfluid 4 He and of normal and spin-polarized 3 He

  16. Interaction of Dopamine Transporter (DAT1) Genotype and Maltreatment for ADHD: A Latent Class Analysis

    Science.gov (United States)

    Li, James J.; Lee, Steve S.

    2012-01-01

    Background: Although the association of the dopamine transporter (DAT1) gene and attention-deficit/hyperactivity disorder (ADHD) has been widely studied, far less is known about its potential interaction with environmental risk factors. Given that maltreatment is a replicated risk factor for ADHD, we explored the interaction between DAT1 and…

  17. Involvement of the carboxyl-terminal region of the yeast peroxisomal half ABC transporter Pxa2p in its interaction with Pxa1p and in transporter function.

    Directory of Open Access Journals (Sweden)

    Cheng-Yi Chuang

    Full Text Available The peroxisome is a single membrane-bound organelle in eukaryotic cells involved in lipid metabolism, including β-oxidation of fatty acids. The human genetic disorder X-linked adrenoleukodystrophy (X-ALD is caused by mutations in the ABCD1 gene (encoding ALDP, a peroxisomal half ATP-binding cassette [ABC] transporter. This disease is characterized by defective peroxisomal β-oxidation and a large accumulation of very long-chain fatty acids in brain white matter, adrenal cortex, and testis. ALDP forms a homodimer proposed to be the functional transporter, whereas the peroxisomal transporter in yeast is a heterodimer comprising two half ABC transporters, Pxa1p and Pxa2p, both orthologs of human ALDP. While the carboxyl-terminal domain of ALDP is engaged in dimerization, it remains unknown whether the same region is involved in the interaction between Pxa1p and Pxa2p.Using a yeast two-hybrid assay, we found that the carboxyl-terminal region (CT of Pxa2p, but not of Pxa1p, is required for their interaction. Further analysis indicated that the central part of the CT (designated CT2 of Pxa2p was indispensable for its interaction with the carboxyl terminally truncated Pxa1_NBD. An interaction between the CT of Pxa2p and Pxa1_NBD was not detected, but could be identified in the presence of Pxa2_NBD-CT1. A single mutation of two conserved residues (aligned with X-ALD-associated mutations at the same positions in ALDP in the CT2 of the Pxa2_NBD-CT protein impaired its interaction with Pxa1_NBD or Pxa1_NBD-CT, resulting in a mutant protein that exhibited a proteinase K digestion profile different from that of the wild-type protein. Functional analysis of these mutant proteins on oleate plates indicated that they were defective in transporter function.The CT of Pxa2p is involved in its interaction with Pxa1p and in transporter function. This concept may be applied to human ALDP studies, helping to establish the pathological mechanism for CT-related X

  18. Interactions Between Channel Topography and Hydrokinetic Turbines: Sediment Transport, Turbine Performance, and Wake Characteristics

    Science.gov (United States)

    Hill, Craig Steven

    Accelerating marine hydrokinetic (MHK) renewable energy development towards commercial viability requires investigating interactions between the engineered environment and its surrounding physical and biological environments. Complex and energetic hydrodynamic and morphodynamic environments desired for such energy conversion installations present difficulties for designing efficient yet robust sustainable devices, while permitting agency uncertainties regarding MHK device environmental interactions result in lengthy and costly processes prior to installing and demonstrating emerging technologies. A research program at St. Anthony Falls Laboratory (SAFL), University of Minnesota, utilized multi-scale physical experiments to study the interactions between axial-flow hydrokinetic turbines, turbulent open channel flow, sediment transport, turbulent turbine wakes, and complex hydro-morphodynamic processes in channels. Model axial-flow current-driven three-bladed turbines (rotor diameters, dT = 0.15m and 0.5m) were installed in open channel flumes with both erodible and non-erodible substrates. Device-induced local scour was monitored over several hydraulic conditions and material sizes. Synchronous velocity, bed elevation and turbine performance measurements provide an indication into the effect channel topography has on device performance. Complimentary experiments were performed in a realistic meandering outdoor research channel with active sediment transport to investigate device interactions with bedform migration and secondary turbulent flow patterns in asymmetric channel environments. The suite of experiments undertaken during this research program at SAFL in multiple channels with stationary and mobile substrates under a variety of turbine configurations provides an in-depth investigation into how axial-flow hydrokinetic devices respond to turbulent channel flow and topographic complexity, and how they impact local and far-field sediment transport characteristics

  19. Simple collision operators for direct Vlasov simulations of laser plasma interaction and transport

    International Nuclear Information System (INIS)

    Arber, T D; Sircombe, N J

    2010-01-01

    Non-local electron transport effects have a direct influence on the compression of cryogenic targets in laser driven ICF and target heating in high energy density experiments. There is a growing need for self-consistent models of laser plasma interactions coupled to nonlocal transport. We present a direct Vlasov solver that includes multiple species and a simple collision operator. This BGK model operator - which conserves particle density, energy and momentum - is fully implicit. For collisionless plasmas it has been shown that a double layer may be formed in which an accelerated, kinetic ion population satisfies the zero current condition. Here we extend this result to collisionalities of interest to laser driven ignition to assess the validity of nonlocal electron transport models based on fluid ions.

  20. Direct interaction between linear electron transfer chains and solute transport systems in bacteria

    NARCIS (Netherlands)

    Elferink, Marieke G.L.; Hellingwerf, Klaas J.; Belkum, Marco J. van; Poolman, Bert; Konings, Wil N.

    1984-01-01

    In studies on alanine and lactose transport in Rhodopseudomonas sphaeroides we have demonstrated that the rate of solute uptake in this phototrophic bacterium is regulated by the rate of light-induced cyclic electron transfer. In the present paper the interaction between linear electron transfer

  1. Development of two-group interfacial area transport equation for confined flow-1. Modeling of bubble interactions

    International Nuclear Information System (INIS)

    Sun, Xiaodong; Kim, Seungjin; Ishii, Mamoru; Beus, Stephen G.

    2003-01-01

    This paper presents the modeling of bubble interaction mechanisms in the two-group interfacial area transport equation (IATE) for confined gas-liquid two-phase flow. The transport equation is applicable to bubbly, cap-turbulent, and churn-turbulent flow regimes. In the two-group IATE, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 and cap/slug/churn-turbulent bubbles as Group 2. Thus, two sets of equations are used to describe the generation and destruction rates of bubble number density, void fraction, and interfacial area concentration for the two groups of bubbles due to bubble expansion and compression, coalescence and disintegration, and phase change. Five major bubble interaction mechanisms are identified for the gas-liquid two-phase flow of interest, and are analytically modeled as the source/sink terms for the transport equations based on certain assumptions for the confined flow. These models include both intra-group (within a certain group) and inter-group (between two groups) bubble interactions. The comparisons of the prediction by the one-dimensional two-group IATE with experimental data are presented in the second paper of this series. (author)

  2. The effect of pre-plasma formation under nonlocal transport conditions for ultra-relativistic laser-plasma interaction

    Science.gov (United States)

    Holec, M.; Nikl, J.; Vranic, M.; Weber, S.

    2018-04-01

    Interaction of high-power lasers with solid targets is in general strongly affected by the limited contrast available. The laser pre-pulse ionizes the target and produces a pre-plasma which can strongly modify the interaction of the main part of the laser pulse with the target. This is of particular importance for future experiments which will use laser intensities above 1021 W cm-2 and which are subject to the limited contrast. As a consequence the main part of the laser pulse will be modified while traversing the pre-plasma, interacting with it partially. A further complication arises from the fact that the interaction of a high-power pre-pulse with solid targets very often takes place under nonlocal transport conditions, i.e. the characteristic mean-free-path of the particles and photons is larger than the characteristic scale-lengths of density and temperature. The classical diffusion treatment of radiation and heat transport in the hydrodynamic model is then insufficient for the description of the pre-pulse physics. These phenomena also strongly modify the formation of the pre-plasma which in turn affects the propagation of the main laser pulse. In this paper nonlocal radiation-hydrodynamic simulations are carried out and serve as input for subsequent kinetic simulations of ultra-high intensity laser pulses interacting with the plasma in the ultra-relativistic regime. It is shown that the results of the kinetic simulations differ considerably whether a diffusive or nonlocal transport is used for the radiation-hydrodynamic simulations.

  3. P-glycoprotein interactions of novel psychoactive substances - stimulation of ATP consumption and transport across Caco-2 monolayers.

    Science.gov (United States)

    Meyer, Markus R; Wagmann, Lea; Schneider-Daum, Nicole; Loretz, Brigitta; de Souza Carvalho, Cristiane; Lehr, Claus-Michael; Maurer, Hans H

    2015-04-01

    In contrast to drugs for therapeutic use, there are only few data available concerning interactions between P-glycoprotein (P-gp) and drugs of abuse (DOA). In this work, interactions between structurally diverse DOA and P-gp were investigated using different strategies. First, the effect on the P-gp ATPase activity was studied by monitoring of ATP consumption after addition to recombinant, human P-gp. Second, DOA showing an increased ATP consumption were further characterized regarding their transport across filter grown Caco-2- monolayers. Analyses were performed by luminescence and liquid chromatography-mass spectrometry, respectively. Among the nine DOA initially screened, benzedrone, diclofensine, glaucine, JWH-200, MDBC, WIN-55,212-2 showed an increase of ATP consumption in the ATPase stimulation assay. In Caco-2 transport studies, Glaucine, JWH-200, mitragynine, WIN-55,212-2 could moreover be identified as non-transported substrates, but inhibitors of P-gp activity. Thus, drug-drug or drug-food interactions should be very likely for these compounds. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Molecular Properties of Drugs Interacting with SLC22 Transporters OAT1, OAT3, OCT1, and OCT2: A Machine-Learning Approach.

    Science.gov (United States)

    Liu, Henry C; Goldenberg, Anne; Chen, Yuchen; Lun, Christina; Wu, Wei; Bush, Kevin T; Balac, Natasha; Rodriguez, Paul; Abagyan, Ruben; Nigam, Sanjay K

    2016-10-01

    Statistical analysis was performed on physicochemical descriptors of ∼250 drugs known to interact with one or more SLC22 "drug" transporters (i.e., SLC22A6 or OAT1, SLC22A8 or OAT3, SLC22A1 or OCT1, and SLC22A2 or OCT2), followed by application of machine-learning methods and wet laboratory testing of novel predictions. In addition to molecular charge, organic anion transporters (OATs) were found to prefer interacting with planar structures, whereas organic cation transporters (OCTs) interact with more three-dimensional structures (i.e., greater SP3 character). Moreover, compared with OAT1 ligands, OAT3 ligands possess more acyclic tetravalent bonds and have a more zwitterionic/cationic character. In contrast, OCT1 and OCT2 ligands were not clearly distinquishable form one another by the methods employed. Multiple pharmacophore models were generated on the basis of the drugs and, consistent with the machine-learning analyses, one unique pharmacophore created from ligands of OAT3 possessed cationic properties similar to OCT ligands; this was confirmed by quantitative atomic property field analysis. Virtual screening with this pharmacophore, followed by transport assays, identified several cationic drugs that selectively interact with OAT3 but not OAT1. Although the present analysis may be somewhat limited by the need to rely largely on inhibition data for modeling, wet laboratory/in vitro transport studies, as well as analysis of drug/metabolite handling in Oat and Oct knockout animals, support the general validity of the approach-which can also be applied to other SLC and ATP binding cassette drug transporters. This may make it possible to predict the molecular properties of a drug or metabolite necessary for interaction with the transporter(s), thereby enabling better prediction of drug-drug interactions and drug-metabolite interactions. Furthermore, understanding the overlapping specificities of OATs and OCTs in the context of dynamic transporter tissue

  5. Cationic uremic toxins affect human renal proximal tubule cell functioning through interaction with the organic cation transporter.

    Science.gov (United States)

    Schophuizen, Carolien M S; Wilmer, Martijn J; Jansen, Jitske; Gustavsson, Lena; Hilgendorf, Constanze; Hoenderop, Joost G J; van den Heuvel, Lambert P; Masereeuw, Rosalinde

    2013-12-01

    Several organic cations, such as guanidino compounds and polyamines, have been found to accumulate in plasma of patients with kidney failure due to inadequate renal clearance. Here, we studied the interaction of cationic uremic toxins with renal organic cation transport in a conditionally immortalized human proximal tubule epithelial cell line (ciPTEC). Transporter activity was measured and validated in cell suspensions by studying uptake of the fluorescent substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium-iodide (ASP(+)). Subsequently, the inhibitory potencies of the cationic uremic toxins, cadaverine, putrescine, spermine and spermidine (polyamines), acrolein (polyamine breakdown product), guanidine, and methylguanidine (guanidino compounds) were determined. Concentration-dependent inhibition of ASP(+) uptake by TPA, cimetidine, quinidine, and metformin confirmed functional endogenous organic cation transporter 2 (OCT2) expression in ciPTEC. All uremic toxins tested inhibited ASP(+) uptake, of which acrolein required the lowest concentration to provoke a half-maximal inhibition (IC50 = 44 ± 2 μM). A Dixon plot was constructed for acrolein using three independent inhibition curves with 10, 20, or 30 μM ASP(+), which demonstrated competitive or mixed type of interaction (K i = 93 ± 16 μM). Exposing the cells to a mixture of cationic uremic toxins resulted in a more potent and biphasic inhibitory response curve, indicating complex interactions between the toxins and ASP(+) uptake. In conclusion, ciPTEC proves a suitable model to study cationic xenobiotic interactions. Inhibition of cellular uptake transport was demonstrated for several uremic toxins, which might indicate a possible role in kidney disease progression during uremia.

  6. Syntaxin 1A interaction with the dopamine transporter promotes amphetamine-induced dopamine efflux

    DEFF Research Database (Denmark)

    Binda, Francesca; Dipace, Concetta; Bowton, Erica

    2008-01-01

    of the dopamine (DA) transporter (DAT) as the site of direct interaction with SYN1A. Amphetamine (AMPH) increases the association of SYN1A with human DAT (hDAT) in a heterologous expression system (hDAT cells) and with native DAT in murine striatal synaptosomes. Immunoprecipitation of DAT from the biotinylated...

  7. An intracellular interaction network regulates conformational transitions in the dopamine transporter

    DEFF Research Database (Denmark)

    Kniazeff, Julie; Shi, Lei; Løland, Claus Juul

    2008-01-01

    Neurotransmitter:sodium symporters (NSS)(1) mediate sodium-dependent reuptake of neurotransmitters from the synaptic cleft and are targets for many psychoactive drugs. The crystal structure of the prokaryotic NSS protein, LeuT, was recently solved at high resolution; however, the mechanistic...... and the intracellular milieu. The mechanism that emerges from these findings may be unique to the NSS family, where the local disruption of ionic interactions modulates the transition of the transporter between the outward- and inward-facing conformations....

  8. GRAVE: An Interactive Geometry Construction and Visualization Software System for the TORT Nuclear Radiation Transport Code

    International Nuclear Information System (INIS)

    Blakeman, E.D.

    2000-01-01

    A software system, GRAVE (Geometry Rendering and Visual Editor), has been developed at the Oak Ridge National Laboratory (ORNL) to perform interactive visualization and development of models used as input to the TORT three-dimensional discrete ordinates radiation transport code. Three-dimensional and two-dimensional visualization displays are included. Display capabilities include image rotation, zoom, translation, wire-frame and translucent display, geometry cuts and slices, and display of individual component bodies and material zones. The geometry can be interactively edited and saved in TORT input file format. This system is an advancement over the current, non-interactive, two-dimensional display software. GRAVE is programmed in the Java programming language and can be implemented on a variety of computer platforms. Three- dimensional visualization is enabled through the Visualization Toolkit (VTK), a free-ware C++ software library developed for geometric and data visual display. Future plans include an extension of the system to read inputs using binary zone maps and combinatorial geometry models containing curved surfaces, such as those used for Monte Carlo code inputs. Also GRAVE will be extended to geometry visualization/editing for the DORT two-dimensional transport code and will be integrated into a single GUI-based system for all of the ORNL discrete ordinates transport codes

  9. Pharmacogenetic Aspects of the Interaction of AT1 Receptor Antagonists With ATP-Binding Cassette Transporter ABCG2

    Directory of Open Access Journals (Sweden)

    Anne Ripperger

    2018-05-01

    Full Text Available The ATP-binding cassette transporter ABCG2 (BCRP and MXR is involved in the absorption, distribution, and elimination of numerous drugs. Thus, drugs that are able to reduce the activity of ABCG2, e.g., antihypertensive AT1 receptor antagonists (ARBs, may cause drug-drug interactions and compromise drug safety and efficacy. In addition, genetic variability within the ABCG2 gene may influence the ability of the transporter to interact with ARBs. Thus, the aim of this study was to characterize the ARB-ABCG2 interaction in the light of naturally occurring variations (F489L, R482G or amino acid substitutions with in silico-predicted relevance for the ARB-ABCG2 interaction (Y469A; M483F; Y570A. For this purpose, ABCG2 variants were expressed in HEK293 cells and the impact of ARBs on ABCG2 activity was studied in vitro using the pheophorbide A (PhA efflux assay. First, we demonstrated that both the F489L and the Y469A substitution, respectively, reduced ABCG2 protein levels in these cells. Moreover, both substitutions enhanced the inhibitory effect of candesartan cilexetil, irbesartan, losartan, and telmisartan on ABCG2-mediated PhA efflux, whereas the R482G substitution blunted the inhibitory effect of candesartan cilexetil and telmisartan in this regard. In contrast, the ARB-ABCG2 interaction was not altered in cells expressing either the M483F or the Y570A variant, respectively. In conclusion, our data indicate that the third transmembrane helix and adjacent regions of ABCG2 may be of major importance for the interaction of ARBs with the ABC transporter. Moreover, we conclude from our data that individuals carrying the F489L polymorphism may be at increased risk of developing ABCG2-related drug-drug interactions in multi-drug regimens involving ARBs.

  10. Phonon transport in a one-dimensional harmonic chain with long-range interaction and mass disorder

    Science.gov (United States)

    Zhou, Hangbo; Zhang, Gang; Wang, Jian-Sheng; Zhang, Yong-Wei

    2016-11-01

    Atomic mass and interatomic interaction are the two key quantities that significantly affect the heat conduction carried by phonons. Here, we study the effects of long-range (LR) interatomic interaction and mass disorder on the phonon transport in a one-dimensional harmonic chain with up to 105 atoms. We find that while LR interaction reduces the transmission of low-frequency phonons, it enhances the transmission of high-frequency phonons by suppressing the localization effects caused by mass disorder. Therefore, LR interaction is able to boost heat conductance in the high-temperature regime or in the large size regime, where the high-frequency modes are important.

  11. Raman Spectroscopic Signature Markers of Dopamine-Human Dopamine Transporter Interaction in Living Cells.

    Science.gov (United States)

    Silwal, Achut P; Yadav, Rajeev; Sprague, Jon E; Lu, H Peter

    2017-07-19

    Dopamine (DA) controls many psychological and behavioral activities in the central nervous system (CNS) through interactions with the human dopamine transporter (hDAT) and dopamine receptors. The roles of DA in the function of the CNS are affected by the targeted binding of drugs to hDAT; thus, hDAT plays a critical role in neurophysiology and neuropathophysiology. An effective experimental method is necessary to study the DA-hDAT interaction and effects of variety of drugs like psychostimulants and antidepressants that are dependent on this interaction. In searching for obtaining and identifying the Raman spectral signatures, we have used surface enhanced Raman scattering (SERS) spectroscopy to record SERS spectra from DA, human embryonic kidney 293 cells (HEK293), hDAT-HEK293, DA-HEK293, and DA-hDAT-HEK293. We have demonstrated a specific 2D-distribution SERS spectral analytical approach to analyze DA-hDAT interaction. Our study shows that the Raman modes at 807, 839, 1076, 1090, 1538, and 1665 cm -1 are related to DA-hDAT interaction, where Raman shifts at 807 and 1076 cm -1 are the signature markers for the bound state of DA to probe DA-hDAT interaction. On the basis of density function theory (DFT) calculation, Raman shift of the bound state of DA at 807 cm -1 is related to combination of bending modes α(C3-O10-H21), α(C2-O11-H22), α(C7-C8-H18), α(C6-C4-H13), α(C7-C8-H19), and α(C7-C8-N9), and Raman shift at 1076 cm -1 is related to combination of bending modes α(H19-N9-C8), γ(N9-H19), γ(C8-H19), γ(N9-H20), γ(C8-H18), and α(C7-C8-H18). These findings demonstrate that protein-ligand interactions can be confirmed by probing change in Raman shift of ligand molecules, which could be crucial to understanding molecular interactions between neurotransmitters and their receptors or transporters.

  12. Regulation of dopamine transporter function by protein-protein interactions: new discoveries and methodological challenges

    DEFF Research Database (Denmark)

    Eriksen, Jacob; Jørgensen, Trine Nygaard; Gether, Ulrik

    2010-01-01

    -synaptic neurons. This has led to the identification of a plethora of different kinases, receptors and scaffolding proteins that interact with DAT and hereby either modulate the catalytic activity of the transporter or regulate its trafficking and degradation. Several new tools for studying DAT regulation in live...

  13. The interaction of horizontal eddy transport and thermal drive in the stratosphere

    Science.gov (United States)

    Salby, Murry L.; O'Sullivan, Donal; Callaghan, Patrick; Garcia, Rolando R.

    1990-01-01

    The two processes that determine the average state of the circulation; i.e., horizontal eddy transport and thermal dissipation, are examined, and the effects of their interaction on circulation and on tracer distribution in the stratosphere are investigated using barotropic calculations on the sphere. It is shown that eddy advection tends to homogenize the meridional gradient Q at low latitudes, while thermal dissipation restores the gradient after episodes of mixing.

  14. Fluid transport due to nonlinear fluid-structure interaction

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    1997-01-01

    This work considers nonlinear fluid-structure interaction for a vibrating pipe containing fluid. Transverse pipe vibrations will force the fluid to move relative to the pipe creating unidirectional fluid flow towards the pipe end. The fluid flow induced affects the damping and the stiffness...... of the pipe. The behavior of the system in response to lateral resonant base excitation is analysed numerically and by the use of a perturbation method (multiple scales). Exciting the pipe in the fundamental mode of vibration seems to be most effective for transferring energy from the shaker to the fluid......, whereas higher modes of vibration can be used to transport fluid with pipe vibrations of smaller amplitude. The effect of the nonlinear geometrical terms is analysed and these terms are shown to affect the response for higher modes of vibration. Experimental investigations show good agreement...

  15. Monitoring Interactions Inside Cells by Advanced Spectroscopies: Overview of Copper Transporters and Cisplatin.

    Science.gov (United States)

    Lasorsa, Alessia; Natile, Giovanni; Rosato, Antonio; Tadini-Buoninsegni, Francesco; Arnesano, Fabio

    2018-02-12

    Resistance, either at the onset of the treatment or developed after an initial positive response, is a major limitation of antitumor therapy. In the case of platinum- based drugs, copper transporters have been found to interfere with drug trafficking by facilitating the import or favoring the platinum export and inactivation. The use of powerful spectroscopic, spectrometric and computational methods has allowed a deep structural insight into the mode of interaction of platinum drugs with the metal-binding domains of the transporter proteins. This review article focuses on the mode in which platinum drugs can compete with copper ion for binding to transport proteins and consequent structural and biological effects. Three types of transporters are discussed in detail: copper transporter 1 (Ctr1), the major responsible for Cu+ uptake; antioxidant-1 copper chaperone (Atox1), responsible for copper transfer within the cytoplasm; and copper ATPases (ATP7A/B), responsible for copper export into specific subcellular compartments and outside the cell. The body of knowledge summarized in this review can help in shaping current chemotherapy to optimize the efficacy of platinum drugs (particularly in relation to resistance) and to mitigate adverse effects on copper metabolism. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Cellular interactions of a lipid-based nanocarrier model with human keratinocytes: Unravelling transport mechanisms.

    Science.gov (United States)

    Silva, Elisabete; Barreiros, Luísa; Segundo, Marcela A; Costa Lima, Sofia A; Reis, Salette

    2017-04-15

    delivery. However these nanocarriers' interactions with epidermal epithelial barrier are yet unknown. Unveiling the mechanisms involved in NLCs transport across the epidermal epithelial monolayers will contribute with valuable information to achieve enhanced skin permeability, superior bioavailability and consequently improved therapeutic effect. With our present work we could certainly provide researchers and clinicians guidance for the design of optimized transdermal delivery systems, based on the nanomaterials and biological interactions. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Thermal transport through a spin-phonon interacting junction: A nonequilibrium Green's function method study

    Science.gov (United States)

    Zhang, Zu-Quan; Lü, Jing-Tao

    2017-09-01

    Using the nonequilibrium Green's function method, we consider heat transport in an insulating ferromagnetic spin chain model with spin-phonon interaction under an external magnetic field. Employing the Holstein-Primakoff transformation to the spin system, we treat the resulted magnon-phonon interaction within the self-consistent Born approximation. We find the magnon-phonon coupling can change qualitatively the magnon thermal conductance in the high-temperature regime. At a spectral mismatched ferromagnetic-normal insulator interface, we also find thermal rectification and negative differential thermal conductance due to the magnon-phonon interaction. We show that these effects can be effectively tuned by the external applied magnetic field, a convenient advantage absent in anharmonic phonon and electron-phonon systems studied before.

  18. Experimental evidence for anisotropic double exchange interaction driven anisotropic transport in manganite heterostructures

    NARCIS (Netherlands)

    Liao, Zhaoliang; Koster, Gertjan; Huijben, Mark; Rijnders, A.J.H.M.

    2017-01-01

    An anisotropic double exchange interaction driven giant transport anisotropy is demonstrated in a canonic double exchange system of La2/3Sr1/3MnO3 ultrathin films epitaxially grown on NdGaO3 (110) substrates. The oxygen octahedral coupling at the La2/3Sr1/3MnO3/NdGaO3 interface induces a planar

  19. Interaction of convective flow generated by human body with room ventilation flow: impact on transport of pollution to the breathing zone

    DEFF Research Database (Denmark)

    Licina, Dusan; Melikov, Arsen Krikor; Sekhar, Chandra

    2014-01-01

    interaction with opposing flow from above and assisting flow from below; and secondly, implication of such a flow interaction on the particle transport from the feet to the breathing zone is examined. The results reveal that the human body heat transports the pollution to the breathing zone and increases......This study aims to investigate the interaction between the human convective boundary layer (CBL) and uniform airflow from two directions and with different velocities. The study has two objectives: first, to characterize the velocity field in the breathing zone of a thermal manikin under its...

  20. Reactive transport modeling of interaction processes between clay stone and cement

    International Nuclear Information System (INIS)

    Windt, L. de; van der Lee, J.; Pellegrini, D.

    2001-01-01

    The disposal of radioactive wastes in clayey formations may require the use of large amounts of concrete and cement. The chemical interactions between these industrial materials and the host rock are modeled with the reactive transport code HYTEC for time scales and a geometry representative of disposal projects. The pH evolution, a key parameter in element mobility, is studied more specifically. It depends on several interdependent processes: i) diffusion of highly alkaline cement pore solution, ii) strong buffering related to important mineral transformations both in the cement and in the clay, and iii) cation exchange processes, beyond the zone of intense mineral transformations. In addition, precipitation of secondary minerals may lead to a partial or complete clogging of the pore space, almost stopping the propagation of the high pH plume. In a second step, preliminary results on the migration of strontium and uranium in these strongly coupled systems are presented as an example of transport parameter derivation. (authors)

  1. Efflux of drugs and solutes from brain: the interactive roles of diffusional transcapillary transport, bulk flow and capillary transporters.

    Science.gov (United States)

    Groothuis, Dennis R; Vavra, Michael W; Schlageter, Kurt E; Kang, Eric W-Y; Itskovich, Andrea C; Hertzler, Shannon; Allen, Cathleen V; Lipton, Howard L

    2007-01-01

    We examined the roles of diffusion, convection and capillary transporters in solute removal from extracellular space (ECS) of the brain. Radiolabeled solutes (eight with passive distribution and four with capillary or cell transporters) were injected into the brains of rats (n=497) and multiple-time point experiments measured the amount remaining in brain as a function of time. For passively distributed compounds, there was a relationship between lipid:water solubility and total brain efflux:diffusional efflux, which dominated when k(p), the transcapillary efflux rate constant, was >10(0) h(-1); when 10(-1)transporters. The total efflux rate constant, k(eff), was the sum of a passive component (k(p)=0.0018 h(-1)), a convective component (k(csf)=0.2 h(-1)), and a variable, concentration-dependent component (k(x)=0 to 0.45 h(-1)). Compounds with cell membrane transporters had longer clearance half times as did an oligonucleotide, which interacted with cell surface receptors. Manipulation of physiologic state (n=35) did not affect efflux, but sucrose efflux half time was longer with pentobarbital anesthesia (24 h) than with no anesthesia or ketamine-xylazine anesthesia (2 to 3 h). These results show that solute clearance from normal brain ECS may involve multiple physiologic pathways, may be affected by anesthesia, and suggests that convection-mediated efflux may be manipulated to increase or decrease drug clearance from brain.

  2. Maternal use of drug substrates of placental transporters and the effect of transporter-mediated drug interactions on the risk of congenital anomalies.

    Directory of Open Access Journals (Sweden)

    Aizati N A Daud

    Full Text Available A number of transporter proteins are expressed in the placenta, and they facilitate the placental transfer of drugs. The inhibition of P-glycoprotein (P-gp was previously found to be associated with an increase in the risk of congenital anomalies caused by drug substrates of this transporter. We now explore the role of other placental transporter proteins.A population-based case-referent study was performed using cases with congenital anomalies (N = 5,131 from EUROCAT Northern Netherlands, a registry of congenital anomalies. The referent population (N = 31,055 was selected from the pregnancy IADB.nl, a pharmacy prescription database.Ten placental transporters known to have comparable expression levels in the placenta to that of P-gp, were selected in this study. In total, 147 drugs were identified to be substrates, inhibitors or inducers, of these transporters. Fifty-eight of these drugs were used by at least one mother in our cases or referent population, and 28 were used in both. The highest user rate was observed for the substrates of multidrug resistance-associated protein 1, mainly folic acid (6% of cases, 8% of referents, and breast cancer resistance protein, mainly nitrofurantoin (2.3% of cases, 2.9% of referents. In contrast to P-gp, drug interactions involving substrates of these transporters did not have a significant effect on the risk of congenital anomalies.Some of the drugs which are substrates or inhibitors of placental transporters were commonly used during pregnancy. No significant effect of transporter inhibition was found on fetal drug exposure, possibly due to a limited number of exposures.

  3. Interaction of Physical and Chemical Processes Controlling the Environmental Fate and Transport of Lampricides Through Stream-Hyporheic Systems

    Science.gov (United States)

    Hixson, J.; Ward, A. S.; Schmadel, N.; McConville, M.; Remucal, C.

    2016-12-01

    The transport and fate of contaminants of emerging concern through the environment is complicated by the heterogeneity of natural systems and the unique reaction pathways of individual compounds. Our current evaluation of risk is often simplified to controls assumed to be homogeneous in space and time. However, we know spatial heterogeneity and time-variable reaction rates complicate predictions of environmental transport and fate, and therefore risk. These complications are the result of the interactions between the physical and chemical systems and the time-variable equilibrium that exists between the two. Compounds that interact with both systems, such as photolytic compounds, require that both components are fully understood in order to predict transport and fate. Release of photolytic compounds occurs through both unintentional releases and intentional loadings. Evaluating risks associated with unintentional releases and implementing best management practices for intentional releases requires an in-depth understanding of the sensitivity of photolytic compounds to external controls. Lampricides, such as 3-trifluoromethyl-4-nitrophenol (TFM), are broadly applied in the Great Lakes system to control the population of invasive sea lamprey. Over-dosing can yield fish kills and other detrimental impacts. Still, planning accounts for time of passage and dilution, but not the interaction of the physical and chemical systems (i.e., storage in the hyporheic zone and time-variable decay rates). In this study, we model a series of TFM applications to test the efficacy of dosing as a function of system characteristics. Overall, our results demonstrate the complexity associated with photo-sensitive compounds through stream-hyporheic systems, and highlight the need to better understand how physical and chemical systems interact to control transport and fate in the environment.

  4. Self-generated magnetic fields and energy transport by ultra-intense laser-plasma interaction

    International Nuclear Information System (INIS)

    Abudurexiti, A.; Tuniyazi, P.; Wang Qian

    2011-01-01

    The electromagnetic instability (Weibel instability) and its mechanism in ultra-intense laser-plasma interactions are studied by using three-dimensional particle-in-cell simulations. The transport of energy in electron thermal conduction is analyzed by the Spitzer-Harm theory, and the election's vertical pyrogenation phenomenon that resulted from anisotropic heating of laser is observed. The results indicate that the strong magnetic field excited by Weibel instability makes the electron beam deposit its energy within a very short distance, and it restrains the electron thermal flux formed when the laser ponderomotive force bursts through the electron. With the increase of the self-generated magnetic field, the electron will be seized by the wave of magnetic field, and the transport of heat will be restricted. (authors)

  5. Effects of electron-electron interactions on electronic transport in disordered systems

    International Nuclear Information System (INIS)

    Foley, Simon Timothy

    2002-01-01

    This thesis is concerned with the role of electron-electron interactions on electronic transport in disordered systems. We first consider a novel non-linear sigma model in order to microscopically treat the effects of disorder and electronic interaction. We successfully reproduce the perturbative results for the zero-bias anomaly and the interaction correction to the conductivity in a weakly disordered system, and discuss possible directions for future work. Secondly we consider the fluctuations of the dephasing rate for a closed diffusive and quantum dot system. Using the Keldysh technique we derive an expression for the inelastic scattering rate with which we self-consistently obtain the fluctuations in the dephasing rate. For the diffusive regime we find the relative fluctuations is given by F ∼ (L φ /L) 2 /g 2 , where g is the dimensionless conductance, L φ is the dephasing length and L is the sample size. For the quantum dot regime we find a perturbative divergence due to the presence of the zero mode. By mapping divergent diagrams to those for the two-level correlation function, we conjecture the existence of an exact relation between the two. Finally we discuss the consequences of this relation. (author)

  6. Taking advantage of reduced droplet-surface interaction to optimize transport of bioanalytes in digital microfluidics.

    Science.gov (United States)

    Freire, Sergio L S; Thorne, Nathaniel; Wutkowski, Michael; Dao, Selina

    2014-11-10

    Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of "lab-on-a-chip" platforms. Often, droplet motion relies on the wetting of a surface, directly associated with the application of an electric field; surface interactions, however, make motion dependent on droplet contents, limiting the breadth of applications of the technique. Some alternatives have been presented to minimize this dependence. However, they rely on the addition of extra chemical species to the droplet or its surroundings, which could potentially interact with droplet moieties. Addressing this challenge, our group recently developed Field-DW devices to allow the transport of cells and proteins in DMF, without extra additives. Here, the protocol for device fabrication and operation is provided, including the electronic interface for motion control. We also continue the studies with the devices, showing that multicellular, relatively large, model organisms can also be transported, arguably unaffected by the electric fields required for device operation.

  7. Electronic Transport as a Driver for Self-Interaction-Corrected Methods

    KAUST Repository

    Pertsova, Anna; Canali, Carlo Maria; Pederson, Mark R.; Rungger, Ivan; Sanvito, Stefano

    2015-01-01

    © 2015 Elsevier Inc. While spintronics often investigates striking collective spin effects in large systems, a very important research direction deals with spin-dependent phenomena in nanostructures, reaching the extreme of a single spin confined in a quantum dot, in a molecule, or localized on an impurity or dopant. The issue considered in this chapter involves taking this extreme to the nanoscale and the quest to use first-principles methods to predict and control the behavior of a few "spins" (down to 1 spin) when they are placed in an interesting environment. Particular interest is on environments for which addressing these systems with external fields and/or electric or spin currents is possible. The realization of such systems, including those that consist of a core of a few transition-metal (TM) atoms carrying a spin, connected and exchanged-coupled through bridging oxo-ligands has been due to work by many experimental researchers at the interface of atomic, molecular and condensed matter physics. This chapter addresses computational problems associated with understanding the behaviors of nano- and molecular-scale spin systems and reports on how the computational complexity increases when such systems are used for elements of electron transport devices. Especially for cases where these elements are attached to substrates with electronegativities that are very different than the molecule, or for coulomb blockade systems, or for cases where the spin-ordering within the molecules is weakly antiferromagnetic, the delocalization error in DFT is particularly problematic and one which requires solutions, such as self-interaction corrections, to move forward. We highlight the intersecting fields of spin-ordered nanoscale molecular magnets, electron transport, and coulomb blockade and highlight cases where self-interaction corrected methodologies can improve our predictive power in this emerging field.

  8. Interactions of C+(2PJ) with rare gas atoms: incipient chemical interactions, potentials and transport coefficients

    Science.gov (United States)

    Tuttle, William D.; Thorington, Rebecca L.; Viehland, Larry A.; Breckenridge, W. H.; Wright, Timothy G.

    2018-03-01

    Accurate interatomic potentials were calculated for the interaction of a singly charged carbon cation, C+, with a single rare gas atom, RG (RG = Ne-Xe). The RCCSD(T) method and basis sets of quadruple-ζ and quintuple-ζ quality were employed; each interaction energy was counterpoise corrected and extrapolated to the basis set limit. The lowest C+(2P) electronic term of the carbon cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: 2Π and 2Σ+. Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. In doing this, anomalously large spin-orbit splittings for RG = Ar-Xe were found, and this was investigated using multi-reference configuration interaction calculations. The latter indicated a small amount of RG → C+ electron transfer and this was used to rationalize the observations. This is taken as evidence of an incipient chemical interaction, which was also examined via contour plots, Birge-Sponer plots and various population analyses across the C+-RG series (RG = He-Xe), with the latter showing unexpected results. Trends in several spectroscopic parameters were examined as a function of the increasing atomic number of the RG atom. Finally, each set of RCCSD(T) potentials was employed, including spin-orbit coupling to calculate the transport coefficients for C+ in RG, and the results were compared with the limited available data. This article is part of the theme issue `Modern theoretical chemistry'.

  9. A specific interdomain interaction preserves the structural and binding properties of the ModA protein from the phytopathogen Xanthomonas citri domain interaction and transport in ModA.

    Science.gov (United States)

    Santacruz-Perez, Carolina; Pegos, Vanessa Rodrigues; Honorato, Rodrigo V; Verli, Hugo; Lindahl, Erik; Barbosa, João Alexandre Ribeiro Gonçalves; Balan, Andrea

    2013-11-01

    The periplasmic-binding proteins in ATP-binding cassette systems (ABC Transporters) are responsible for the capture and delivery of ligands to their specific transporters, triggering a series of ATP-driven conformational changes that leads to the transport of the ligand. Structurally consisting of two lobes, the proteins change conformation after interaction with the ligand. The structure of the molybdate-binding protein (ModA) from Xanthomonas citri, bound to molybdate, was previously solved by our group and an interdomain interaction, mediated by a salt bridge between K127 and D59, apparently supports the binding properties and keeps the domains closed. To determinate the importance of this interaction, we built two ModA mutants, K127S and D59A, and analysed their functional and structural properties. Based on a set of spectroscopic experiments, crystallisation trials, structure determination and molecular dynamics (MD) simulations, we showed that the salt bridge is essential to maintain the structure and binding properties. Additionally, the MD simulations revealed that this mutant adopted a more compact structure that packed down the ligand-binding pocket. From the closed bound to open structure, the positioning of the helices forming the dipole and the salt bridge are essential to induce an intermediate state. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Multi-scale interactions affecting transport, storage, and processing of solutes and sediments in stream corridors (Invited)

    Science.gov (United States)

    Harvey, J. W.; Packman, A. I.

    2010-12-01

    Surface water and groundwater flow interact with the channel geomorphology and sediments in ways that determine how material is transported, stored, and transformed in stream corridors. Solute and sediment transport affect important ecological processes such as carbon and nutrient dynamics and stream metabolism, processes that are fundamental to stream health and function. Many individual mechanisms of transport and storage of solute and sediment have been studied, including surface water exchange between the main channel and side pools, hyporheic flow through shallow and deep subsurface flow paths, and sediment transport during both baseflow and floods. A significant challenge arises from non-linear and scale-dependent transport resulting from natural, fractal fluvial topography and associated broad, multi-scale hydrologic interactions. Connections between processes and linkages across scales are not well understood, imposing significant limitations on system predictability. The whole-stream tracer experimental approach is popular because of the spatial averaging of heterogeneous processes; however the tracer results, implemented alone and analyzed using typical models, cannot usually predict transport beyond the very specific conditions of the experiment. Furthermore, the results of whole stream tracer experiments tend to be biased due to unavoidable limitations associated with sampling frequency, measurement sensitivity, and experiment duration. We recommend that whole-stream tracer additions be augmented with hydraulic and topographic measurements and also with additional tracer measurements made directly in storage zones. We present examples of measurements that encompass interactions across spatial and temporal scales and models that are transferable to a wide range of flow and geomorphic conditions. These results show how the competitive effects between the different forces driving hyporheic flow, operating at different spatial scales, creates a situation

  11. Thermal transport across metal–insulator interface via electron–phonon interaction

    International Nuclear Information System (INIS)

    Zhang, Lifa; Wang, Jian-Sheng; Li, Baowen; Lü, Jing-Tao

    2013-01-01

    The thermal transport across a metal–insulator interface can be characterized by electron–phonon interaction through which an electron lead is coupled to a phonon lead if phonon–phonon coupling at the interface is very weak. We investigate the thermal conductance and rectification between the electron part and the phonon part using the nonequilibrium Green’s function method. It is found that the thermal conductance has a nonmonotonic behavior as a function of average temperature or the coupling strength between the phonon leads in the metal part and the insulator part. The metal–insulator interface shows a clear thermal rectification effect, which can be reversed by a change in average temperature or the electron–phonon coupling. (paper)

  12. Current correlations for the transport of interacting electrons through parallel quantum dots in a photon cavity

    Science.gov (United States)

    Gudmundsson, Vidar; Abdullah, Nzar Rauf; Sitek, Anna; Goan, Hsi-Sheng; Tang, Chi-Shung; Manolescu, Andrei

    2018-06-01

    We calculate the current correlations for the steady-state electron transport through multi-level parallel quantum dots embedded in a short quantum wire, that is placed in a non-perfect photon cavity. We account for the electron-electron Coulomb interaction, and the para- and diamagnetic electron-photon interactions with a stepwise scheme of configuration interactions and truncation of the many-body Fock spaces. In the spectral density of the temporal current-current correlations we identify all the transitions, radiative and non-radiative, active in the system in order to maintain the steady state. We observe strong signs of two types of Rabi oscillations.

  13. Transport through interacting quantum dots with Majorana fermions or phonons

    International Nuclear Information System (INIS)

    Huetzen, Roland

    2013-01-01

    Recent advances in the search for Majorana fermions within condensed matter systems inspired the first part of the thesis. These hypothetical particles which are their own antiparticles are predicted to arise in the form of quasi-particle excitations called Majorana bound states at the surface of engineered condensed matter systems. An experimental detection is challenging since their defining property also implies that they possess no charge, no energy and no spin. This significantly reduces the possibilities to interact with them and get a proof of their existence from a measurement. The most promising experimental results are based on transport measurements where current-voltage-characteristics play the role of a spectroscopy signal. In this thesis, we investigate a single electron transistor setup which hosts a spatially separated pair of Majorana fermions with respect to their influence on its transport characteristics. We focus on a master equation approach including sequential and cotunneling contributions. After deducing all relevant rates we solve the system numerically over a broad parameter regime. For some limits, we also elaborate analytical solutions. In comparison with collaboratively worked out other methods we provide a broad understanding of the setup and make a proposal how our results could be used as a detection scheme for Majorana fermions. The second part of the thesis investigates the spinless Anderson-Holstein model which is the minimal model for molecular transport. It models a molecule with electronic and vibronic degrees of freedom which is placed between metallic leads at different chemical potentials to investigate again its transport properties. Also here we intended to gain access to a broad parameter regime and successfully extended the numerical ''iterative summation of path-integrals'' scheme to this model. It is based on a real-time path-integral approach in combination with the nonequilibrium Keldysh

  14. Transport through interacting quantum dots with Majorana fermions or phonons

    Energy Technology Data Exchange (ETDEWEB)

    Huetzen, Roland

    2013-07-04

    Recent advances in the search for Majorana fermions within condensed matter systems inspired the first part of the thesis. These hypothetical particles which are their own antiparticles are predicted to arise in the form of quasi-particle excitations called Majorana bound states at the surface of engineered condensed matter systems. An experimental detection is challenging since their defining property also implies that they possess no charge, no energy and no spin. This significantly reduces the possibilities to interact with them and get a proof of their existence from a measurement. The most promising experimental results are based on transport measurements where current-voltage-characteristics play the role of a spectroscopy signal. In this thesis, we investigate a single electron transistor setup which hosts a spatially separated pair of Majorana fermions with respect to their influence on its transport characteristics. We focus on a master equation approach including sequential and cotunneling contributions. After deducing all relevant rates we solve the system numerically over a broad parameter regime. For some limits, we also elaborate analytical solutions. In comparison with collaboratively worked out other methods we provide a broad understanding of the setup and make a proposal how our results could be used as a detection scheme for Majorana fermions. The second part of the thesis investigates the spinless Anderson-Holstein model which is the minimal model for molecular transport. It models a molecule with electronic and vibronic degrees of freedom which is placed between metallic leads at different chemical potentials to investigate again its transport properties. Also here we intended to gain access to a broad parameter regime and successfully extended the numerical ''iterative summation of path-integrals'' scheme to this model. It is based on a real-time path-integral approach in combination with the nonequilibrium Keldysh

  15. Water-mediated interactions enable smooth substrate transport in a bacterial efflux pump.

    Science.gov (United States)

    Vargiu, Attilio Vittorio; Ramaswamy, Venkata Krishnan; Malvacio, Ivana; Malloci, Giuliano; Kleinekathöfer, Ulrich; Ruggerone, Paolo

    2018-04-01

    Efflux pumps of the Resistance-Nodulation-cell Division superfamily confer multi-drug resistance to Gram-negative bacteria. The most-studied polyspecific transporter belonging to this class is the inner-membrane trimeric antiporter AcrB of Escherichia coli. In previous studies, a functional rotation mechanism was proposed for its functioning, according to which the three monomers undergo concerted conformational changes facilitating the extrusion of substrates. However, the molecular determinants and the energetics of this mechanism still remain unknown, so its feasibility must be proven mechanistically. A computational protocol able to mimic the functional rotation mechanism in AcrB was developed. By using multi-bias molecular dynamics simulations we characterized the translocation of the substrate doxorubicin driven by conformational changes of the protein. In addition, we estimated for the first time the free energy profile associated to this process. We provided a molecular view of the process in agreement with experimental data. Moreover, we showed that the conformational changes occurring in AcrB enable the formation of a layer of structured waters on the internal surface of the transport channel. This water layer, in turn, allows for a fairly constant hydration of the substrate, facilitating its diffusion over a smooth free energy profile. Our findings reveal a new molecular mechanism of polyspecific transport whereby water contributes by screening potentially strong substrate-protein interactions. We provided a mechanistic understanding of a fundamental process related to multi-drug transport. Our results can help rationalizing the behavior of other polyspecific transporters and designing compounds avoiding extrusion or inhibitors of efflux pumps. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  16. Evaluation of a potential transporter-mediated drug interaction between rosuvastatin and pradigastat, a novel DGAT-1 inhibitor.

    Science.gov (United States)

    Kulmatycki, Kenneth; Hanna, Imad; Meyers, Dan; Salunke, Atish; Movva, Aishwarya; Majumdar, Tapan; Natrillo, Adrienne; Vapurcuyan, Arpine; Rebello, Sam; Sunkara, Gangadhar; Chen, Jin

    2015-05-01

    An in vitro drugdrug interaction (DDI) study was performed to assess the potential for pradigastat to inhibit breast cancer resistance protein (BCRP), organic anion-transporting polypeptide (OATP), and organic anion transporter 3 (OAT3) transport activities. To understand the relevance of these in vitro findings, a clinical pharmacokinetic DDI study using rosuvastatin as a BCRP, OATP, and OAT3 probe substrate was conducted. The study used cell lines that stably expressed or over-expressed the respective transporters. The clinical study was an open-label, single sequence study where subjects (n = 36) received pradigastat (100 mg once daily x 3 days thereafter 40 mg once daily) and rosuvastatin (10 mg once daily), alone and in combination. Pradigastat inhibited BCRP-mediated efflux activity in a dose-dependent fashion in a BCRP over-expressing human ovarian cancer cell line with an IC(50) value of 5 μM. Similarly, pradigastat inhibited OATP1B1, OATP1B3 (estradiol 17β glucuronide transport), and OAT3 (estrone 3 sulfate transport) activity in a concentrationdependent manner with estimated IC(50) values of 1.66 ± 0.95 μM, 3.34 ± 0.64 μM, and 0.973 ± 0.11 μM, respectively. In the presence of steady state pradigastat concentrations, AUC(τ, ss) of rosuvastatin was unchanged and its Cmax,ss decreased by 14% (5.30 and 4.61 ng/mL when administered alone and coadministered with pradigastat, respectively). Pradigastat AUC(τ, ss) and C(max, ss) were unchanged when coadministered with rosuvastatin at steady state. Both rosuvastatin and pradigastat were well tolerated. These data indicate no clinically relevant pharmacokinetic interaction between pradigastat and rosuvastatin.

  17. Effect of spin-orbit interactions on the structural stability, thermodynamic properties, and transport properties of lead under pressure

    Science.gov (United States)

    Smirnov, N. A.

    2018-03-01

    The paper investigates the role of spin-orbit interaction in the prediction of structural stability, lattice dynamics, elasticity, thermodynamic and transport properties (electrical resistivity and thermal conductivity) of lead under pressure with the FP-LMTO (full-potential linear-muffin-tin orbital) method for the first-principles band structure calculations. Our calculations were carried out for three polymorphous lead modifications (fcc, hcp, and bcc) in generalized gradient approximation with the exchange-correlation functional PBEsol. They suggest that compared to the scalar-relativistic calculation, the account for the SO effects insignificantly influences the compressibility of Pb. At the same time, in the calculation of phonon spectra and transport properties, the role of SO interaction is important, at least, for P ≲150 GPa. At higher pressures, the contribution from SO interaction reduces but not vanishes. As for the relative structural stability, our studies show that SO effects influence weakly the pressure of the fcc →hcp transition and much higher the pressure of the hcp →bcc transition.

  18. Spatial and thickness dependence of coupling interaction of surface states and influence on transport and optical properties of few-layer Bi2Se3

    Science.gov (United States)

    Li, Zhongjun; Chen, Shi; Sun, Jiuyu; Li, Xingxing; Qiu, Huaili; Yang, Jinlong

    2018-02-01

    Coupling interaction between the bottom and top surface electronic states and the influence on transport and optical properties of Bi2Se3 thin films with 1-8 quintuple layers (QLs) have been investigated by first principles calculations. Obvious spatial and thickness dependences of coupling interaction are found by analyzing hybridization of two surface states. In the thin film with a certain thickness, from the outer to inner atomic layers, the coupling interaction exhibits an increasing trend. On the other hand, as thickness increases, the coupling interaction shows a disproportionate decrease trend. Moreover, the system with 3 QLs exhibits stronger interaction than that with 2 QLs. The presence of coupling interaction would suppress destructive interference of surface states and enhance resistance in various degrees. In view of the inversely proportional relation to transport channel width, the resistance of thin films should show disproportionate thickness dependence. This prediction is qualitatively consistent with the transport measurements at low temperature. Furthermore, the optical properties also exhibit obvious thickness dependence. Especially as the thickness increases, the coupling interaction results in red and blue shifts of the multiple-peak structures in low and high energy regions of imaginary dielectric function, respectively. The red shift trend is in agreement with the recent experimental observation and the blue shift is firstly predicted by the present calculation. The present results give a concrete understanding of transport and optical properties in devices based on Bi2Se3 thin films with few QLs.

  19. Modeling multicomponent ionic transport in groundwater with IPhreeqc coupling: Electrostatic interactions and geochemical reactions in homogeneous and heterogeneous domains

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Rolle, Massimo

    2016-01-01

    is coupled with the geochemical code PHREEQC-3 by utilizing the IPhreeqc module, thus enabling to perform the geochemical calculations included in the PHREEQC's reaction package. The multicomponent reactive transport code is benchmarked with different 1-D and 2-D transport problems. Successively...... the electrostatic interactions during transport of charged ions in physically and chemically heterogeneous porous media. The modeling approach is based on the local charge balance and on the description of compound-specific and spatially variable diffusive/dispersive fluxes. The multicomponent ionic transport code......, conservative and reactive transport examples are presented to demonstrate the capability of the proposed model to simulate transport of charged species in heterogeneous porous media with spatially variable physical and chemical properties. The results reveal that the Coulombic cross-coupling between dispersive...

  20. Crew/Automation Interaction in Space Transportation Systems: Lessons Learned from the Glass Cockpit

    Science.gov (United States)

    Rudisill, Marianne

    2000-01-01

    The progressive integration of automation technologies in commercial transport aircraft flight decks - the 'glass cockpit' - has had a major, and generally positive, impact on flight crew operations. Flight deck automation has provided significant benefits, such as economic efficiency, increased precision and safety, and enhanced functionality within the crew interface. These enhancements, however, may have been accrued at a price, such as complexity added to crew/automation interaction that has been implicated in a number of aircraft incidents and accidents. This report briefly describes 'glass cockpit' evolution. Some relevant aircraft accidents and incidents are described, followed by a more detailed description of human/automation issues and problems (e.g., crew error, monitoring, modes, command authority, crew coordination, workload, and training). This paper concludes with example principles and guidelines for considering 'glass cockpit' human/automation integration within space transportation systems.

  1. Modeling Groundwater-Surface Water Interaction and Contaminant Transport of Chlorinated Solvent Contaminated Site

    Science.gov (United States)

    Yimer Ebrahim, Girma; Jonoski, Andreja; van Griensven, Ann; Dujardin, Juliette; Baetelaan, Okke; Bronders, Jan

    2010-05-01

    Chlorinated-solvent form one of the largest groups of environmental chemicals. Their use and misuse in industry have lead to a large entry of these chemicals into the environment, resulting in widespread dissemination and oftentimes environmental contamination. Chlorinated solvent contamination of groundwater resources has been widely reported. For instance, there has been much interest in the assessment of these contaminant levels and their evolutions with time in the groundwater body below the Vilvoorde-Machelen industrial area (Belgium). The long industrial history of the area has lead to complex patterns of pollution from multiple sources and the site has been polluted to the extent that individual plumes are not definable any more. Understanding of groundwater/surface water interaction is a critical component for determining the fate of contaminant both in streams and ground water due to the fact that groundwater and surface water are in continuous dynamic interaction in the hydrologic cycle. The interaction has practical consequences in the quantity and quality of water in either system in the sense that depletion and/or contamination of one of the system will eventually affect the other one. The transition zone between a stream and its adjacent aquifer referred to as the hyporheic zone plays a critical role in governing contaminant exchange and transformation during water exchange between the two water bodies. The hyporheic zone of Zenne River ( the main receptor ) is further complicated due to the fact that the river banks are artificially trained with sheet piles along its reach extending some 12 m below the surface. This study demonstrates the use of MODFLOW, a widely used modular three-dimensional block-centred finite difference, saturated flow model for simulating the flow and direction of movement of groundwater through aquifer and stream-aquifer interaction and the use of transport model RT3D, a three-dimensional multi-species reactive transport model

  2. A Crowdsensing-Based Real-Time System for Finger Interactions in Intelligent Transport System

    Directory of Open Access Journals (Sweden)

    Chengqun Song

    2017-01-01

    Full Text Available Crowdsensing leverages human intelligence/experience from the general public and social interactions to create participatory sensor networks, where context-aware and semantically complex information is gathered, processed, and shared to collaboratively solve specific problems. This paper proposes a real-time projector-camera finger system based on the crowdsensing, in which user can interact with a computer by bare hand touching on arbitrary surfaces. The interaction process of the system can be completely carried out automatically, and it can be used as an intelligent device in intelligent transport system where the driver can watch and interact with the display information while driving, without causing visual distractions. A single camera is used in the system to recover 3D information of fingertip for hand touch detection. A linear-scanning method is used in the system to determine the touch for increasing the users’ collaboration and operationality. Experiments are performed to show the feasibility of the proposed system. The system is robust to different lighting conditions. The average percentage of correct hand touch detection of the system is 92.0% and the average time of processing one video frame is 30 milliseconds.

  3. Endocytic Uptake, Transport and Macromolecular Interactions of Anionic PAMAM Dendrimers within Lung Tissue.

    Science.gov (United States)

    Morris, Christopher J; Aljayyoussi, Ghaith; Mansour, Omar; Griffiths, Peter; Gumbleton, Mark

    2017-12-01

    Polyamidoamine (PAMAM) dendrimers are a promising class of nanocarrier with applications in both small and large molecule drug delivery. Here we report a comprehensive evaluation of the uptake and transport pathways that contribute to the lung disposition of dendrimers. Anionic PAMAM dendrimers and control dextran probes were applied to an isolated perfused rat lung (IPRL) model and lung epithelial monolayers. Endocytosis pathways were examined in primary alveolar epithelial cultures by confocal microscopy. Molecular interactions of dendrimers with protein and lipid lung fluid components were studied using small angle neutron scattering (SANS). Dendrimers were absorbed across the intact lung via a passive, size-dependent transport pathway at rates slower than dextrans of similar molecular sizes. SANS investigations of concentration-dependent PAMAM transport in the IPRL confirmed no aggregation of PAMAMs with either albumin or dipalmitoylphosphatidylcholine lung lining fluid components. Distinct endocytic compartments were identified within primary alveolar epithelial cells and their functionality in the rapid uptake of fluorescent dendrimers and model macromolecular probes was confirmed by co-localisation studies. PAMAM dendrimers display favourable lung biocompatibility but modest lung to blood absorption kinetics. These data support the investigation of dendrimer-based carriers for controlled-release drug delivery to the deep lung.

  4. Evaluating Otto the Auto: Does Engagement in an Interactive Website Improve Young Children's Transportation Safety?

    Science.gov (United States)

    Schwebel, David C; Johnston, Anna; Shen, Jiabin; Li, Peng

    2017-07-19

    Transportation-related injuries are a leading cause of pediatric death, and effective interventions are limited. Otto the Auto is a website offering engaging, interactive activities. We evaluated Otto among a sample of sixty-nine 4- and 5-year-old children, who participated in a randomized parallel group design study. Following baseline evaluation, children engaged with either Otto or a control website for 2 weeks and then were re-evaluated. Children who used Otto failed to show increases in transportation safety knowledge or behavior compared to the control group, although there was a dosage effect whereby children who engaged in the website more with parents gained safer behavior patterns. We conclude Otto may have some efficacy when engaged by children with their parents, but continued efforts to develop and refine engaging, effective, theory-driven strategies to teach children transportation safety, including via internet, should be pursued.

  5. Drug membrane interaction and the importance for drug transport, distribution, accumulation, efficacy and resistance.

    Science.gov (United States)

    Seydel, J K; Coats, E A; Cordes, H P; Wiese, M

    1994-10-01

    Some aspects of drug membrane interaction and its influence on drug transport, accumulation, efficacy and resistance have been discussed. The interactions manifest themselves macroscopically in changes in the physical and thermodynamic properties of "pure membranes" or bilayers. As various amounts of foreign molecules enter the membrane, in particular the main gel to liquid crystalline phase transition can be dramatically changed. This may change permeability, cell-fusion, cell resistance and may also lead to changes in conformation of the embedded receptor proteins. Furthermore, specific interactions with lipids may lead to drug accumulation in membranes and thus to much larger concentrations at the active site than present in the surrounding water phase. The lipid environment may also lead to changes in the preferred conformation of drug molecules. These events are directly related to drug efficacy. The determination of essential molecular criteria for the interaction could be used to design new and more selective therapeutics. This excursion in some aspects of drug membrane interaction underlines the importance of lipids and their interaction with drug molecules for our understanding of drug action, but this is not really a new thought but has been formulated in 1884 by THUDICUM: "Phospholipids are the centre, life and chemical soul of all bioplasm whatsoever, that of plants as well as of animals".

  6. Transport and interaction blockade of cold bosonic atoms in a triple-well potential

    International Nuclear Information System (INIS)

    Schlagheck, P; Malet, F; Cremon, J C; Reimann, S M

    2010-01-01

    We theoretically investigate the transport properties of cold bosonic atoms in a quasi-one-dimensional (1D) triple-well potential that consists of two large outer wells, which act as microscopic source and drain reservoirs, and a small inner well, which represents a quantum-dot-like scattering region. Bias and gate 'voltages' introduce a time-dependent tilt of the triple-well configuration, and are used to shift the energetic level of the inner well with respect to the outer ones. By means of exact diagonalization considering a total number of six atoms in the triple-well potential, we find diamond-like structures for the occurrence of single-atom transport in the parameter space spanned by the bias and gate voltages. We discuss the analogy with Coulomb blockade in electronic quantum dots, and point out how one can infer the interaction energy in the central well from the distance between the diamonds.

  7. Potential interaction between transport and stream networks over the lowland rivers in Eastern India.

    Science.gov (United States)

    Roy, Suvendu; Sahu, Abhay Sankar

    2017-07-15

    Extension of transport networks supports good accessibility and associated with the development of a region. However, transport lines have fragmented the regional landscape and disturbed the natural interplay between rivers and their floodplains. Spatial analysis using multiple buffers provides information about the potential interaction between road and stream networks and their impact on channel morphology of a small watershed in the Lower Gangetic Plain. Present study is tried to understand the lateral and longitudinal disconnection in headwater stream by rural roads with the integration of geoinformatics and field survey. Significant (p development, delineation of stream corridor, regular monitoring and engineering efficiency for the construction of road and road-stream crossing might be effective in managing river geomorphology and riverine landscape. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Impact of airflow interaction on inhaled air quality and transport of contaminants in rooms with personalized and total volume ventilation

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Cermak, Radim; Kovar, O.

    2003-01-01

    The impact of airflow interaction on inhaled air quality and transport of contaminants between occupants was studied in regard to pollution from floor covering, human bioeffluents and exhaled air, with combinations of two personalized ventilation systems (PV) with mixing and displacement...... quality with personalized and mixing ventilation was higher or at least similar compared to mixing ventilation alone. In the case of PV combined with displacement ventilation, the interaction caused mixing of the room air, an increase in the transport of bioeffluents and exhaled air between occupants and...... ventilation. In total, 80 L/s of clean air supplied at 20°C was distributed between the ventilation systems at different combinations of personalized airflow rate. Two breathing thermal manikins were used to simulate occupants in a full-scale test room. Regardless of the airflow interaction, the inhaled air...

  9. Interactions between cask components and content of packaging for the transport of radioactive material during drop tests

    International Nuclear Information System (INIS)

    Quercetti, T.; Ballheimer, V.; Zeisler, P.; Mueller, K.

    2003-01-01

    This paper describes the analytical, numerical and experimental investigations on the phenomenon of interactions between cask components and content of packages for the transport of radioactive material during drop tests required according to the IAEA Regulations for the Safe Transport of Radioactive Material. Radial and axial gaps between cask components and content are usually necessary for thermal reasons but larger gaps can exist because of the geometrical dimensions of the specified content. Consequently interactions between content and cask components (lid system, cask body, etc.) are possible and can not be excluded during drop tests. Interactions in this context are relative movements between cask and content which are mainly due to elastic spring effects after releasing the cask for the free drop. These relative movements can cause interior collisions between content and cask during the main impact of the package onto the unyielding target. Drop tests with various types of Type A and Type B packages fully instrumented with strain gauges and accelerometers showed that these interactions respectively interior collisions can be considerable relating to high forces acting on cask lids, lid bolts and the content. Of course the real quantitative consequences of the interactions depend upon different conditions, among others the drop orientation, the design characteristics of the impact limiters, the dimensions of the gaps, the material characteristics of the contents, etc. . In order to investigate more precisely the phenomenon of interactions BAM carried out finite element calculations for the named casks using the ABAQUS/ Standard and ABAQUS/ Explicit computer code comparing them with results obtained from experiments. Additionally, tests with a simplified model instrumented with accelerometers were carried out accompanied by finite element calculations and analytical calculations using MATHEMATICA. The investigations on the mentioned phenomena of interaction

  10. Design, Development, and Innovation of an Interactive Multimedia Training Simulator for Responding to Air Transportation Bomb Threats

    Science.gov (United States)

    Chung, Christopher A.; Marwaha, Shweta

    2005-01-01

    This paper describes an interactive multimedia simulator for air transportation bomb threat training. The objective of this project is to improve the air transportation sector s capability to respond to bomb threats received by commercial airports and aircraft. The simulator provides realistic training on receiving and responding to a variety of bomb threats that might not otherwise be possible due to time, cost, or operational constraints. Validation analysis indicates that the use of the simulator resulted in statistically significant increases in individual ability to respond to these types of bomb threats.

  11. Interaction of Sp1 zinc finger with transport factor in the nuclear localization of transcription factor Sp1

    International Nuclear Information System (INIS)

    Ito, Tatsuo; Kitamura, Haruka; Uwatoko, Chisana; Azumano, Makiko; Itoh, Kohji; Kuwahara, Jun

    2010-01-01

    Research highlights: → Sp1 zinc fingers themselves interact with importin α. → Sp1 zinc finger domains play an essential role as a nuclear localization signal. → Sp1 can be transported into the nucleus in an importin-dependent manner. -- Abstract: Transcription factor Sp1 is localized in the nucleus and regulates the expression of many cellular genes, but the nuclear transport mechanism of Sp1 is not well understood. In this study, we revealed that GST-fused Sp1 protein bound to endogenous importin α in HeLa cells via the Sp1 zinc finger domains, which comprise the DNA binding domain of Sp1. It was found that the Sp1 zinc finger domains directly interacted with a wide range of importin α including the armadillo (arm) repeat domain and the C-terminal acidic domain. Furthermore, it turned out that all three zinc fingers of Sp1 are essential for binding to importin α. Taken together, these results suggest that the Sp1 zinc finger domains play an essential role as a NLS and Sp1 can be transported into the nucleus in an importin-dependent manner even though it possesses no classical NLSs.

  12. Stable isotope reactive transport modeling in water-rock interactions during CO2 injection

    Science.gov (United States)

    Hidalgo, Juan J.; Lagneau, Vincent; Agrinier, Pierre

    2010-05-01

    Stable isotopes can be of great usefulness in the characterization and monitoring of CO2 sequestration sites. Stable isotopes can be used to track the migration of the CO2 plume and identify leakage sources. Moreover, they provide unique information about the chemical reactions that take place on the CO2-water-rock system. However, there is a lack of appropriate tools that help modelers to incorporate stable isotope information into the flow and transport models used in CO2 sequestration problems. In this work, we present a numerical tool for modeling the transport of stable isotopes in groundwater reactive systems. The code is an extension of the groundwater single-phase flow and reactive transport code HYTEC [2]. HYTEC's transport module was modified to include element isotopes as separate species. This way, it is able to track isotope composition of the system by computing the mixing between the background water and the injected solution accounting for the dependency of diffusion on the isotope mass. The chemical module and database have been expanded to included isotopic exchange with minerals and the isotope fractionation associated with chemical reactions and mineral dissolution or precipitation. The performance of the code is illustrated through a series of column synthetic models. The code is also used to model the aqueous phase CO2 injection test carried out at the Lamont-Doherty Earth Observatory site (Palisades, New York, USA) [1]. References [1] N. Assayag, J. Matter, M. Ader, D. Goldberg, and P. Agrinier. Water-rock interactions during a CO2 injection field-test: Implications on host rock dissolution and alteration effects. Chemical Geology, 265(1-2):227-235, July 2009. [2] Jan van der Lee, Laurent De Windt, Vincent Lagneau, and Patrick Goblet. Module-oriented modeling of reactive transport with HYTEC. Computers & Geosciences, 29(3):265-275, April 2003.

  13. Interactions of solutes and streambed sediment: 1. An experimental analysis of cation and anion transport in a mountain stream

    Science.gov (United States)

    Bencala, Kenneth E.; Kennedy, Vance C.; Zellweger, Gary W.; Jackman, Alan P.; Avanzino, Ronald J.

    1984-01-01

    An experimental injection was performed to study the transport of stream water solutes under conditions of significant interaction with streambed sediments in a mountain pool-and-riffle stream. Experiments were conducted in Little Lost Man Creek, Humboldt County, California, in a period of low flow duringwhich only a part of the bank-full channel held active surface flow. The injection of chloride and several trace cations lasted 20 days. In this report we discuss the results of the first 24 hours of the injection and survey the results of the first 10 days. Solute-streambed interactions of two types were observed. First, the physical transport of the conservative tracer, chloride, was affected by intergravel flow and stagnant watt, zones created by the bed relief. Second, the transport of the cations (strontium, potassium, and lithium) was appreciably modified by sorption onto streambed sediment. In the stream the readily observable consequence of the solute-streambed interactions was an attenuation of the dissolved concentration of each of the tracers. The attenuation in the stream channel occurred concurrently with the storage of tracers in the streambed via both physical and chemical processes. All tracers were subsequently present in shallow wells dug several meters from the wetted part of the channel. Sediment samples collected approximately 3 weeks after the start of the injection contained increased concentrations of the injected cations.

  14. Ligand-Receptor Interaction-Mediated Transmembrane Transport of Dendrimer-like Soft Nanoparticles: Mechanisms and Complicated Diffusive Dynamics.

    Science.gov (United States)

    Liang, Junshi; Chen, Pengyu; Dong, Bojun; Huang, Zihan; Zhao, Kongyin; Yan, Li-Tang

    2016-05-09

    Nearly all nanomedical applications of dendrimer-like soft nanoparticles rely on the functionality of attached ligands. Understanding how the ligands interact with the receptors in cell membrane and its further effect on the cellular uptake of dendrimer-like soft nanoparticles is thereby a key issue for their better application in nanomedicine. However, the essential mechanism and detailed kinetics for the ligand-receptor interaction-mediated transmembrane transport of such unconventional nanoparticles remain poorly elucidated. Here, using coarse-grained simulations, we present the very first study of molecular mechanism and kinetics behaviors for the transmembrane transport of dendrimer-like soft nanoparticles conjugated with ligands. A phase diagram of interaction states is constructed through examining ligand densities and membrane tensions that allows us to identify novel endocytosis mechanisms featured by the direct wrapping and the penetration-extraction vesiculation. The results provide an in-depth insight into the diffusivity of receptors and dendrimer in the membrane plane and demonstrate how the ligand density influences receptor diffusion and uptake kinetics. It is interesting to find that the ligand-conjugated dendrimers present superdiffusive behaviors on a membrane, which is revealed to be driven by the random fluctuation dynamics of the membrane. The findings facilitate our understanding of some recent experimental observations and could establish fundamental principles for the future development of such important nanomaterials for widespread nanomedical applications.

  15. Effects of electron-phonon interaction on thermal and electrical transport through molecular nano-conductors

    Energy Technology Data Exchange (ETDEWEB)

    Lü, Jing-Tao, E-mail: jtlu@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, 430074 Wuhan (China); Zhou, Hangbo [Department of Physics and Center for Computational Science and Engineering, National University of Singapore, 117551 Singapore (Singapore); NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 117456 Singapore (Singapore); Jiang, Jin-Wu [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai University, 200072 Shanghai (China); Wang, Jian-Sheng [Department of Physics and Center for Computational Science and Engineering, National University of Singapore, 117551 Singapore (Singapore)

    2015-05-15

    The topic of this review is the effects of electron-phonon interaction (EPI) on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green’s function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system’s thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor’s atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons.

  16. Effects of electron-phonon interaction on thermal and electrical transport through molecular nano-conductors

    International Nuclear Information System (INIS)

    Lü, Jing-Tao; Zhou, Hangbo; Jiang, Jin-Wu; Wang, Jian-Sheng

    2015-01-01

    The topic of this review is the effects of electron-phonon interaction (EPI) on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green’s function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system’s thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor’s atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons

  17. Transporters affecting biochemical test results: Creatinine-drug interactions.

    Science.gov (United States)

    Chu, X; Bleasby, K; Chan, G H; Nunes, I; Evers, R

    2016-11-01

    Creatinine is eliminated by the kidneys through a combination of glomerular filtration and active transport. Drug-induced increases in serum creatinine (SCr) and/or reduced creatinine renal clearance are used as a marker for acute kidney injury. However, inhibition of active transport of creatinine can result in reversible and, therefore, benign increases in SCr levels. Herein, the transporters involved in creatinine clearance are discussed, in addition to limitations of using creatinine as a biomarker for kidney damage. © 2016 American Society for Clinical Pharmacology and Therapeutics.

  18. Interaction of antidepressants with the serotonin and norepinephrine transporters

    DEFF Research Database (Denmark)

    Sørensen, Lena; Andersen, Jacob; Thomsen, Mette

    2012-01-01

    The serotonin transporter (SERT) and the norepinephrine transporter (NET) are sodium-dependent neurotransmitter transporters responsible for reuptake of released serotonin and norepinephrine, respectively, into nerve terminals in the brain. A wide range of inhibitors of SERT and NET are used...

  19. Coulombic interactions and multicomponent ionic dispersion during transport of charged species in heterogeneous porous media

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Rolle, Massimo

    Electrochemical cross-coupling plays a significant role for transport of charged species in porous media [1, 2]. In this study we performed flow-through experiments in a quasi two-dimensional setup using dilute solutions of strong electrolytes to study the influence of charge interactions on mass...... occurred. To quantitatively interpret the outcomes of our laboratory experiments in the spatially variable flow fields we developed a two dimensional numerical model based on a multicomponent formulation, on charge conservation and on the accurate description of transverse dispersion. The results...... of the multicomponent transport simulations were compared with the high-resolution (5 mm spacing) concentration measurements of the ionic species at the outlet of the flow-through domain. The excellent agreement between the measured concentrations and the results of purely forward numerical simulations demonstrates...

  20. Diffusion, Coulombic interactions and multicomponent ionic transport of charged species in saturated porous media

    DEFF Research Database (Denmark)

    Rolle, Massimo; Muniruzzaman, Muhammad

    water are cross-coupled due to the effects of Coulombic interactions. Such effects are illustrated in flow-through experiments in saturated porous media. Simple strong electrolytes (i.e., salts and strong acid solutions) were selected as tracers and their transport was studied under different advection......-dominated conditions in homogeneous and heterogeneous porous media [2-3]. The model-based interpretation of the experimental results is challenging since it requires a multicomponent ionic formulation with an accurate description of local hydrodynamic dispersion and explicitly accounting for the cross-coupling...

  1. Validation of a microdose probe drug cocktail for clinical drug interaction assessments for drug transporters and CYP3A.

    Science.gov (United States)

    Prueksaritanont, T; Tatosian, D A; Chu, X; Railkar, R; Evers, R; Chavez-Eng, C; Lutz, R; Zeng, W; Yabut, J; Chan, G H; Cai, X; Latham, A H; Hehman, J; Stypinski, D; Brejda, J; Zhou, C; Thornton, B; Bateman, K P; Fraser, I; Stoch, S A

    2017-04-01

    A microdose cocktail containing midazolam, dabigatran etexilate, pitavastatin, rosuvastatin, and atorvastatin has been established to allow simultaneous assessment of a perpetrator impact on the most common drug metabolizing enzyme, cytochrome P450 (CYP)3A, and the major transporters organic anion-transporting polypeptides (OATP)1B, breast cancer resistance protein (BCRP), and MDR1 P-glycoprotein (P-gp). The clinical utility of these microdose cocktail probe substrates was qualified by conducting clinical drug interaction studies with three inhibitors with different in vitro inhibitory profiles (rifampin, itraconazole, and clarithromycin). Generally, the pharmacokinetic profiles of the probe substrates, in the absence and presence of the inhibitors, were comparable to their reported corresponding pharmacological doses, and/or in agreement with theoretical expectations. The exception was dabigatran, which resulted in an approximately twofold higher magnitude for microdose compared to conventional dosing, and, thus, can be used to flag a worst-case scenario for P-gp. Broader application of the microdose cocktail will facilitate a more comprehensive understanding of the roles of drug transporters in drug disposition and drug interactions. © 2016 American Society for Clinical Pharmacology and Therapeutics.

  2. Groundwater-Surface Water Interactions and Downstream Transport of Water, Heat, and Solutes in a Hydropeaked River

    Science.gov (United States)

    Ferencz, S. B.; Cardenas, M. B.; Neilson, B. T.; Watson, J.

    2017-12-01

    A majority of the world's largest river systems are regulated by dams. In addition to being used for water resources management and flood prevention, many large dams are also used for hydroelectric power generation. In the United States, dams account for 7% of domestic electricity, and hydropower accounts for 16% of worldwide electricity production. To help meet electricity demand during peak usage times, hydropower utilities often increase their releases of water during high demand periods. This practice, termed hydropeaking, can cause large transient flow regimes downstream of hydroelectric dams. These transient flow increases can result in order of magnitude daily fluctuations in discharge, and the released water can have different thermal and chemical properties than ambient river water. As hydropeaking releases travel downstream, the temporary rise in stage and increase in discharge can enhance surface water-groundwater (SW-GW) exchange between the river and its alluvial aquifer. This dam-induced SW-GW exchange, combined with hydrodynamic attenuation and heat exchange processes, result in complex responses downstream. The dam-regulated Lower Colorado River downstream of Austin, TX was used as a natural laboratory to observe SW-GW interactions and downstream transport of water, heat, and solutes under hydropeaking conditions. To characterize SW-GW interactions, well transects were installed in the banks of the river to observe exchanges between the river and alluvial aquifer. The well transects were installed at three different distances from the dam (15km, 35km, and 80km). At each well transect conductivity, temperature, and pressure sensors were deployed in the monitoring wells and in the channel. Additional conductivity and temperature sensors were deployed along the study reach to provide a more detailed record of heat and solute transport during hydropeaking releases. The field data spans over two months of daily dam releases that were punctuated by two

  3. Polymorphisms in ATP-binding cassette transporter genes and interaction with diet and life style factors in relation to colorectal cancer in a Danish prospective case-cohort study

    DEFF Research Database (Denmark)

    Kopp, Tine Iskov; Andersen, Vibeke; Tjonneland, Anne

    2015-01-01

    to assess whether polymorphisms in ABCB1, ABCC2 and ABCG2 were associated with risk of colorectal cancer (CRC) and to investigate gene-environment (dietary factors, smoking and use of non-steroidal anti-inflammatory drugs) and gene-gene interactions between previously studied polymorphisms in IL1B and IL10......The ATP-binding cassette (ABC) transporter family transports various molecules across the enterocytes in the gut protecting the intestine against potentially harmful substances. Moreover, ABC transporters are involved in mucosal immune defence through interaction with cytokines. The study aimed...... of the polymorphisms were associated with CRC, but ABCB1 and ABCG2 haplotypes were associated with risk of CRC. ABCB1/rs1045642 interacted with intake of cereals and fiber (p-Value for interaction (Pint) = 0.001 and 0.01, respectively). In a three-way analysis, both ABCB1/rs1045642 and ABCG2/rs2231137 in combination...

  4. Influence of Dzyaloshinskii-Moriya interaction and ballistic spin transport in the two and three-dimensional Heisenberg model

    Science.gov (United States)

    Lima, L. S.

    2018-06-01

    We study the effect of Dzyaloshisnkii-Moriya interaction on spin transport in the two and three-dimensional Heisenberg antiferromagnetic models in the square lattice and cubic lattice respectively. For the three-dimensional model, we obtain a large peak for the spin conductivity and therefore a finite AC conductivity. For the two-dimensional model, we have gotten the AC spin conductivity tending to the infinity at ω → 0 limit and a suave decreasing in the spin conductivity with increase of ω. We obtain a small influence of the Dzyaloshinskii-Moriya interaction on the spin conductivity in all cases analyzed.

  5. Serotonin Transporter-Linked Polymorphic Region (5-HTTLPR) Genotype and Stressful Life Events Interact to Predict Preschool-Onset Depression: A Replication and Developmental Extension

    Science.gov (United States)

    Bogdan, Ryan; Agrawal, Arpana; Gaffrey, Michael S.; Tillman, Rebecca; Luby, Joan L.

    2014-01-01

    Background: Scientific enthusiasm about gene × environment interactions, spurred by the 5-HTTLPR (serotonin transporter-linked polymorphic region) × SLEs (stressful life events) interaction predicting depression, have recently been tempered by sober realizations of small effects and meta-analyses reaching opposing conclusions. These mixed findings…

  6. Anisotropic spin transport affected by competition between spin orbit interaction and Zeeman effect in an InGaAs based wire

    International Nuclear Information System (INIS)

    Nitta, Junsaku; Moulis, Sylvain; Kohda, Makoto

    2011-01-01

    Spin transport affected by competition between Zeeman effect and spin-orbit interaction (SOI) is investigated in order to check a proposed method to deduce the Rashba SOI α and Dresselhaus SOI β ratio. The experimentally obtained ratio α/β of the present sample is about 4 from angle dependence of magnetoconductance under in-plane magnetic field. The proposed method to detect the ratio by transport measurement is promising although further improvement of sample fabrication and measurement is required.

  7. A physical model describing the interaction of nuclear transport receptors with FG nucleoporin domain assemblies.

    Science.gov (United States)

    Zahn, Raphael; Osmanović, Dino; Ehret, Severin; Araya Callis, Carolina; Frey, Steffen; Stewart, Murray; You, Changjiang; Görlich, Dirk; Hoogenboom, Bart W; Richter, Ralf P

    2016-04-08

    The permeability barrier of nuclear pore complexes (NPCs) controls bulk nucleocytoplasmic exchange. It consists of nucleoporin domains rich in phenylalanine-glycine motifs (FG domains). As a bottom-up nanoscale model for the permeability barrier, we have used planar films produced with three different end-grafted FG domains, and quantitatively analyzed the binding of two different nuclear transport receptors (NTRs), NTF2 and Importin β, together with the concomitant film thickness changes. NTR binding caused only moderate changes in film thickness; the binding isotherms showed negative cooperativity and could all be mapped onto a single master curve. This universal NTR binding behavior - a key element for the transport selectivity of the NPC - was quantitatively reproduced by a physical model that treats FG domains as regular, flexible polymers, and NTRs as spherical colloids with a homogeneous surface, ignoring the detailed arrangement of interaction sites along FG domains and on the NTR surface.

  8. Interaction of H2S with Calcium Permeable Channels and Transporters

    Directory of Open Access Journals (Sweden)

    Weihua Zhang

    2015-01-01

    Full Text Available A growing amount of evidence has suggested that hydrogen sulfide (H2S, as a gasotransmitter, is involved in intensive physiological and pathological processes. More and more research groups have found that H2S mediates diverse cellular biological functions related to regulating intracellular calcium concentration. These groups have demonstrated the reciprocal interaction between H2S and calcium ion channels and transporters, such as L-type calcium channels (LTCC, T-type calcium channels (TTCC, sodium/calcium exchangers (NCX, transient receptor potential (TRP channels, β-adrenergic receptors, and N-methyl-D-aspartate receptors (NMDAR in different cells. However, the understanding of the molecular targets and mechanisms is incomplete. Recently, some research groups demonstrated that H2S modulates the activity of calcium ion channels through protein S-sulfhydration and polysulfide reactions. In this review, we elucidate that H2S controls intracellular calcium homeostasis and the underlying mechanisms.

  9. Transporter taxonomy - a comparison of different transport protein classification schemes.

    Science.gov (United States)

    Viereck, Michael; Gaulton, Anna; Digles, Daniela; Ecker, Gerhard F

    2014-06-01

    Currently, there are more than 800 well characterized human membrane transport proteins (including channels and transporters) and there are estimates that about 10% (approx. 2000) of all human genes are related to transport. Membrane transport proteins are of interest as potential drug targets, for drug delivery, and as a cause of side effects and drug–drug interactions. In light of the development of Open PHACTS, which provides an open pharmacological space, we analyzed selected membrane transport protein classification schemes (Transporter Classification Database, ChEMBL, IUPHAR/BPS Guide to Pharmacology, and Gene Ontology) for their ability to serve as a basis for pharmacology driven protein classification. A comparison of these membrane transport protein classification schemes by using a set of clinically relevant transporters as use-case reveals the strengths and weaknesses of the different taxonomy approaches.

  10. Interactive Effects of the Serotonin Transporter 5-HTTLPR Polymorphism and Stressful Life Events on College Student Drinking and Drug Use

    NARCIS (Netherlands)

    Covault, J.; Tennen, H.; Armeli, S.; Conner, T.S.; Herman, A.I.; Cillessen, A.H.N.; Kranzler, H.R.

    2007-01-01

    Background - A common functional polymorphism, 5-HTTLPR, in the serotonin transporter gene has been associated with heavy drinking in college students. We examined this polymorphism as it interacted with negative life events to predict drinking and drug use in college students. Methods - Daily

  11. Spin-orbit coupling effects, interactions and superconducting transport in nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Andreas

    2010-05-15

    the RKKY Hamiltonian on both RSOC and interaction strength and an anisotropic range function. In the second part of this thesis we focus on the study of superconducting transport in a quantum dot Josephson junctions coupled to a two-level system, which serves as a simple model for a conformational degree of freedom of a molecular dot or a break junction. We first address the limit of weak coupling to the leads and calculate the critical current through the junction perturbatively to lowest nonvanishing order in the tunneling couplings, allowing for arbitrary charging energy U and TLS parameters. We show that the critical current can change by orders of magnitude due to the two-level system. In particular, the {pi}-junction behavior, generally present for strong interactions, can be completely suppressed. We also study the influence of the Josephson current on the state of the TLS in the regime of weak charging energy. Within a wide range of parameters, our calculations predict that the TLS is quite sensitive to a variation of the phase difference {phi} across the junction. Conformational changes, up to a a complete reversal, can be induced by varying {phi}. This allows for the dissipationless control (including switching) of the TLS. (orig.)

  12. Spin-orbit coupling effects, interactions and superconducting transport in nanostructures

    International Nuclear Information System (INIS)

    Schulz, Andreas

    2010-05-01

    the RKKY Hamiltonian on both RSOC and interaction strength and an anisotropic range function. In the second part of this thesis we focus on the study of superconducting transport in a quantum dot Josephson junctions coupled to a two-level system, which serves as a simple model for a conformational degree of freedom of a molecular dot or a break junction. We first address the limit of weak coupling to the leads and calculate the critical current through the junction perturbatively to lowest nonvanishing order in the tunneling couplings, allowing for arbitrary charging energy U and TLS parameters. We show that the critical current can change by orders of magnitude due to the two-level system. In particular, the π-junction behavior, generally present for strong interactions, can be completely suppressed. We also study the influence of the Josephson current on the state of the TLS in the regime of weak charging energy. Within a wide range of parameters, our calculations predict that the TLS is quite sensitive to a variation of the phase difference φ across the junction. Conformational changes, up to a a complete reversal, can be induced by varying φ. This allows for the dissipationless control (including switching) of the TLS. (orig.)

  13. Role of electrostatic interactions on the transport of druglike molecules in hydrogel-based articular cartilage mimics

    DEFF Research Database (Denmark)

    Ye, Fengbin; Baldursdottir, Stefania G.; Hvidt, Søren

    2016-01-01

    In the field of drug delivery to the articular cartilage, it is advantageous to apply artificial tissue models as surrogates of cartilage for investigating drug transport and release properties. In this study, artificial cartilage models consisting of 0.5% (w/v) agarose gel containing 0.5% (w...... to the pure agarose gel. The decrease in apparent diffusivity of the cationic compounds was not caused by a change in the gel structure since a similar reduction in apparent diffusivity was not observed for the net negatively charged protein α-lactalbumin. The apparent diffusivity of the cationic compounds...... the electrostatic nature of their interactions. The results obtained from the UV imaging diffusion studies are important for understanding the effect of drug physicochemical properties on the transport in articular cartilage. The extracted information may be useful in the development of hydrogels for in vitro...

  14. Transport-induced correlations in weakly interacting systems

    International Nuclear Information System (INIS)

    Bunin, Guy; Kafri, Yariv; Podolsky, Daniel; Lecomte, Vivien; Polkovnikov, Anatoli

    2013-01-01

    We study spatial correlations in the transport of energy between two baths at different temperatures. To do this, we introduce a minimal model in which energy flows from one bath to another through two subsystems. We show that the transport-induced energy correlations between the two subsystems are of the same order as the energy fluctuations within each subsystem. The correlations can be either positive or negative and we give bounds on their values which are associated with a dynamic energy scale. The different signs originate as a competition between fluctuations generated near the baths and fluctuations of the current between the two subsystems. This interpretation sheds light on known results for spatially-dependent heat and particle conduction models. (paper)

  15. Implication of the C terminus of the Prunus necrotic ringspot virus movement protein in cell-to-cell transport and in its interaction with the coat protein.

    Science.gov (United States)

    Aparicio, Frederic; Pallás, Vicente; Sánchez-Navarro, Jesús

    2010-07-01

    The movement protein (MP) of Prunus necrotic ringspot virus (PNRSV) is required for viral transport. Previous analysis with MPs of other members of the family Bromoviridae has shown that the C-terminal part of these MPs plays a critical role in the interaction with the cognate coat protein (CP) and in cell-to-cell transport. Bimolecular fluorescence complementation and overlay analysis confirm an interaction between the C-terminal 38 aa of PNRSV MP and its cognate CP. Mutational analysis of the C-terminal region of the PNRSV MP revealed that its C-terminal 38 aa are dispensable for virus transport, however, the 4 aa preceding the dispensable C terminus are necessary to target the MP to the plasmodesmata and for the functionality of the protein. The capacity of the PNRSV MP to use either a CP-dependent or a CP-independent cell-to-cell transport is discussed.

  16. Diffusion equation and spin drag in spin-polarized transport

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Jensen, Thomas Stibius; Mortensen, Asger

    2001-01-01

    We study the role of electron-electron interactions for spin-polarized transport using the Boltzmann equation, and derive a set of coupled transport equations. For spin-polarized transport the electron-electron interactions are important, because they tend to equilibrate the momentum of the two-s...

  17. Molecular interaction of selected phytochemicals under the charged environment of Plasmodium falciparum chloroquine resistance transporter (PfCRT) model.

    Science.gov (United States)

    Patel, Saumya K; Khedkar, Vijay M; Jha, Prakash C; Jasrai, Yogesh T; Pandya, Himanshu A; George, Linz-Buoy; Highland, Hyacinth N; Skelton, Adam A

    2016-01-01

    Phytochemicals of Catharanthus roseus Linn. and Tylophora indica have been known for their inhibition of malarial parasite, Plasmodium falciparum in cell culture. Resistance to chloroquine (CQ), a widely used antimalarial drug, is due to the CQ resistance transporter (CRT) system. The present study deals with computational modeling of Plasmodium falciparum chloroquine resistance transporter (PfCRT) protein and development of charged environment to mimic a condition of resistance. The model of PfCRT was developed using Protein homology/analogy engine (PHYRE ver 0.2) and was validated based on the results obtained using PSI-PRED. Subsequently, molecular interactions of selected phytochemicals extracted from C. roseus Linn. and T. indica were studied using multiple-iterated genetic algorithm-based docking protocol in order to investigate the translocation of these legends across the PfCRT protein. Further, molecular dynamics studies exhibiting interaction energy estimates of these compounds within the active site of the protein showed that compounds are more selective toward PfCRT. Clusters of conformations with the free energy of binding were estimated which clearly demonstrated the potential channel and by this means the translocation across the PfCRT is anticipated.

  18. Early life adversity and serotonin transporter gene variation interact to affect DNA methylation of the corticotropin-releasing factor gene promoter region in the adult rat brain

    NARCIS (Netherlands)

    Doelen, R.H.A. van der; Arnoldussen, I.A.C.; Ghareh, H.; Och, L. van; Homberg, J.R.; Kozicz, L.T.

    2015-01-01

    The interaction between childhood maltreatment and the serotonin transporter (5-HTT) gene linked polymorphic region has been associated with increased risk to develop major depression. This Gene x Environment interaction has furthermore been linked with increased levels of anxiety and glucocorticoid

  19. The transportation institutional plan: Cooperative planning for NWPA transportation

    International Nuclear Information System (INIS)

    Denny, S.H.; Livingston-Behan, E.A.

    1987-01-01

    The Transportation Institutional Plan, published in 1986 by the U.S. Department of Energy's Office of Civilian Radioactive Waste Management (OCRWM), defines a process for effective interaction among those who may be affected by transportation activities conducted under provisions of the Nuclear Waste Policy Act of 1982 (NWPA). The Plan describes formal mechanisms for identifying, addressing, and resolving specific transportation issues. An appendix to the Plan includes detailed discussion of the following transportation issues: (1) the transportation of defense waste; (2) prenotification; (3) physical and rail shipments; (4) highway routing; (5) rail routing; (6) inspection and enforcement for highway and rail shipments; (7) emergency response; (8) liability coverage for transportation to NWPA facilities; (9) cask design and testing; (10) overweight truck shipments; (11) rail service analysis; (12) mixture of transportation modes; (13) transportation infrastructure improvements; (14) OCRWM training standards; (15) transportation operational procedures; and (16) State, Tribal, and local regulation of transportation. The OCRWM's intent is to provide an open accounting of planning, to identify opportunities for public involvement in program activities, and to foster communication and negotiation in the cooperative development of a safe, efficient, and cost-effective NWPA transportation program

  20. A Process-Based Transport-Distance Model of Aeolian Transport

    Science.gov (United States)

    Naylor, A. K.; Okin, G.; Wainwright, J.; Parsons, A. J.

    2017-12-01

    We present a new approach to modeling aeolian transport based on transport distance. Particle fluxes are based on statistical probabilities of particle detachment and distributions of transport lengths, which are functions of particle size classes. A computational saltation model is used to simulate transport distances over a variety of sizes. These are fit to an exponential distribution, which has the advantages of computational economy, concordance with current field measurements, and a meaningful relationship to theoretical assumptions about mean and median particle transport distance. This novel approach includes particle-particle interactions, which are important for sustaining aeolian transport and dust emission. Results from this model are compared with results from both bulk- and particle-sized-specific transport equations as well as empirical wind tunnel studies. The transport-distance approach has been successfully used for hydraulic processes, and extending this methodology from hydraulic to aeolian transport opens up the possibility of modeling joint transport by wind and water using consistent physics. Particularly in nutrient-limited environments, modeling the joint action of aeolian and hydraulic transport is essential for understanding the spatial distribution of biomass across landscapes and how it responds to climatic variability and change.

  1. Thermal-chemical-mechanical feedback during fluid-rock interactions: Implications for chemical transport and scales of equilibria in the crust

    International Nuclear Information System (INIS)

    Dutrow, Barbara

    2008-01-01

    Our research evaluates the hypothesis that feedback amongst thermal-chemical-mechanical processes operative in fluid-rock systems alters the fluid flow dynamics of the system which, in turn, affects chemical transport and temporal and spatial scales of equilibria, thus impacting the resultant mineral textural development of rocks. Our methods include computational experimentation and detailed analyses of fluid-infiltrated rocks from well-characterized terranes. This work focuses on metamorphic rocks and hydrothermal systems where minerals and their textures are utilized to evaluate pressure (P), temperature (T), and time (t) paths in the evolution of mountain belts and ore deposits, and to interpret tectonic events and the timing of these events. Our work on coupled processes also extends to other areas where subsurface flow and transport in porous media have consequences such as oil and gas movement, geothermal system development, transport of contaminants, nuclear waste disposal, and other systems rich in fluid-rock reactions. Fluid-rock systems are widespread in the geologic record. Correctly deciphering the products resulting from such systems is important to interpreting a number of geologic phenomena. These systems are characterized by complex interactions involving time-dependent, non-linear processes in heterogeneous materials. While many of these interactions have been studied in isolation, they are more appropriately analyzed in the context of a system with feedback. When one process impacts another process, time and space scales as well as the overall outcome of the interaction can be dramatically altered. Our goals to test this hypothesis are: to develop and incorporate algorithms into our 3D heat and mass transport code to allow the effects of feedback to be investigated numerically, to analyze fluid infiltrated rocks from a variety of terranes at differing P-T conditions, to identify subtle features of the infiltration of fluids and/or feedback, and

  2. Interactions and feedbacks among phytobenthos, hydrodynamics, nutrient cycling and sediment transport in estuarine ecosystems

    Science.gov (United States)

    Bergamasco, A.; De Nat, L.; Flindt, M. R.; Amos, C. L.

    2003-11-01

    Phytobenthic communities can play an active role in modifying the environmental characteristics of the ecosystem in which they live so mediating the human impact on Coastal Zone habitats. Complicated feedbacks couple the establishment of phytobenthic communities with water quality and physical parameters in estuaries. Direct and indirect interactions between physical and biological attributes need to be considered in order to improve the management of these ecosystems to guarantee a sustainable use of coastal resources. Within the project F-ECTS ("Feedbacks of Estuarine Circulation and Transport of Sediments on phytobenthos") this issue was approached through a three-step strategy: (i) Monitoring: detailed fieldwork activities focusing on the measurement and evaluation of the main processes involving hydrodynamics, sediments, nutrients, light and phytobenthic biomass; (ii) Modeling: joint modeling of the suspended particulate matter erosion/transport/deposition and biological mediation of the hydrodynamics and (iii) GIS: development of GIS-based practical tools able to manage and exploit measured and modeled data on the basis of scientific investigation guidelines and procedures. The overall strategy is described by illustrating results of field measurements, providing details of model implementation and demonstrating the GIS-based tools.

  3. 3D Structure and Interaction of p24β and p24δ Golgi Dynamics Domains: Implication for p24 Complex Formation and Cargo Transport.

    Science.gov (United States)

    Nagae, Masamichi; Hirata, Tetsuya; Morita-Matsumoto, Kana; Theiler, Romina; Fujita, Morihisa; Kinoshita, Taroh; Yamaguchi, Yoshiki

    2016-10-09

    The p24 family consists of four subfamilies (p24α, p24β, p24γ, and p24δ), and the proteins are thought to form hetero-oligomeric complexes for efficient transport of cargo proteins from the endoplasmic reticulum to the Golgi apparatus. The proteins possess a conserved luminal Golgi dynamics (GOLD) domain, whose functions are largely unknown. Here, we present structural and biochemical studies of p24β1 and p24δ1 GOLD domains. Use of GOLD domain-deleted mutants revealed that the GOLD domain of p24δ1 is required for proper p24 hetero-oligomeric complex formation and efficient transport of GPI-anchored proteins. The p24β1 and p24δ1 GOLD domains share a common β-sandwich fold with a characteristic intrasheet disulfide bond. The GOLD domain of p24δ1 crystallized as dimers, allowing the analysis of a homophilic interaction site. Surface plasmon resonance and solution NMR analyses revealed that p24β1 and p24δ1 GOLD domains interact weakly (K d = ~10 -4 M). Bi-protein titration provided interaction site maps. We propose that the heterophilic interaction of p24 GOLD domains contributes to the formation of the p24 hetero-oligomeric complex and to efficient cargo transport. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. The interactive effects of transportation and lairage time on welfare indicators, carcass and meat quality traits in slaughter pigs

    Science.gov (United States)

    Čobanović, N.; Vasilev, D.; Dimitrijević, M.; Teodorović, V.; Parunović, N.; Betić, N.; Karabasil, N.

    2017-09-01

    This study assessed the effects of transportation and lairage time and their interaction on welfare, carcass and meat quality traits in slaughter pigs under commercial conditions. The study was conducted on 120 pigs with a live weight of approximately 115 kg and about six months old. A complete blood picture was measured in pigs to assess pre-slaughter stress. Also, nine different carcass quality parameters including live weight, hot and cold carcass weights, cooling loss, dressing percentage, backfat thickness, meatiness and skin lesions score were measured. The pH and temperature measurements were performed 45 minutes post-mortem. The results showed that short transportation time and slaughtering without lairaging and long transportation time and overnight lairaging negatively influenced the hematological parameters, which meant that the animal welfare was seriously compromised under these pre-slaughter conditions. Long transportation time and overnight lairaging reduced live and carcass weights and increased the incidence of skin lesions on the carcass and DFD pork. In addition, short transportation time and slaughtering without lairaging caused a significant deterioration in pork quality. It can be concluded that, from the standpoint of animal welfare, carcass and meat quality, the above-mentioned pre-slaughter conditions are not recommended to the farmers and/or pork producers.

  5. Electroluminescence Caused by the Transport of Interacting Electrons through Parallel Quantum Dots in a Photon Cavity

    Science.gov (United States)

    Gudmundsson, Vidar; Abdulla, Nzar Rauf; Sitek, Anna; Goan, Hsi-Sheng; Tang, Chi-Shung; Manolescu, Andrei

    2018-02-01

    We show that a Rabi-splitting of the states of strongly interacting electrons in parallel quantum dots embedded in a short quantum wire placed in a photon cavity can be produced by either the para- or the dia-magnetic electron-photon interactions when the geometry of the system is properly accounted for and the photon field is tuned close to a resonance with the electron system. We use these two resonances to explore the electroluminescence caused by the transport of electrons through the one- and two-electron ground states of the system and their corresponding conventional and vacuum electroluminescense as the central system is opened up by coupling it to external leads acting as electron reservoirs. Our analysis indicates that high-order electron-photon processes are necessary to adequately construct the cavity-photon dressed electron states needed to describe both types of electroluminescence.

  6. X-ray spectroscopic technique for energetic electron transport studies in short-pulse laser/plasma interactions

    Energy Technology Data Exchange (ETDEWEB)

    Tutt, T.E.

    1994-12-01

    When a solid target is irradiated by a laser beam, the material is locally heated to a high temperature and a plasma forms. The interaction of the laser with plasma can produce energetic electrons. By observing the behavior of these {open_quotes}hot{close_quotes} electrons, we hope to obtain a better understanding of Laser/Plasma Interactions. In this work we employ a layered-fluorescer technique to study the transport, and therefore the energetics, of the electrons. The plasma forms on a thin foil of metallic Pd which is bonded to thin layer of metallic Sn. Electrons formed from the plasma penetrate first the Pd and then the Sn. In both layers the energetic electrons promote inner (K) shell ionization of the metallic atoms which leads to the emission of characteristic K{sub {alpha}} x-rays of the fluorescers. By recording the x-ray spectrum emitted by the two foils, we can estimate the energy-dependent range of the electrons and their numbers.

  7. PERMEABILITY, SOLUBILITY, AND INTERACTION OF HYDROGEN IN POLYMERS- AN ASSESSMENT OF MATERIALS FOR HYDROGEN TRANSPORT

    Energy Technology Data Exchange (ETDEWEB)

    Kane, M

    2008-02-05

    Fiber-reinforced polymer (FRP) piping has been identified as a leading candidate for use in a transport system for the Hydrogen Economy. Understanding the permeation and leakage of hydrogen through the candidate materials is vital to effective materials system selection or design and development of safe and efficient materials for this application. A survey of the literature showed that little data on hydrogen permeation are available and no mechanistically-based models to quantitatively predict permeation behavior have been developed. However, several qualitative trends in gaseous permeation have been identified and simple calculations have been performed to identify leakage rates for polymers of varying crystallinity. Additionally, no plausible mechanism was found for the degradation of polymeric materials in the presence of pure hydrogen. The absence of anticipated degradation is due to lack of interactions between hydrogen and FRP and very low solubility coefficients of hydrogen in polymeric materials. Recommendations are made to address research and testing needs to support successful materials development and use of FRP materials for hydrogen transport and distribution.

  8. A mechanistic framework for in vitro-in vivo extrapolation of liver membrane transporters: prediction of drug-drug interaction between rosuvastatin and cyclosporine.

    Science.gov (United States)

    Jamei, M; Bajot, F; Neuhoff, S; Barter, Z; Yang, J; Rostami-Hodjegan, A; Rowland-Yeo, K

    2014-01-01

    The interplay between liver metabolising enzymes and transporters is a complex process involving system-related parameters such as liver blood perfusion as well as drug attributes including protein and lipid binding, ionisation, relative magnitude of passive and active permeation. Metabolism- and/or transporter-mediated drug-drug interactions (mDDIs and tDDIs) add to the complexity of this interplay. Thus, gaining meaningful insight into the impact of each element on the disposition of a drug and accurately predicting drug-drug interactions becomes very challenging. To address this, an in vitro-in vivo extrapolation (IVIVE)-linked mechanistic physiologically based pharmacokinetic (PBPK) framework for modelling liver transporters and their interplay with liver metabolising enzymes has been developed and implemented within the Simcyp Simulator(®). In this article an IVIVE technique for liver transporters is described and a full-body PBPK model is developed. Passive and active (saturable) transport at both liver sinusoidal and canalicular membranes are accounted for and the impact of binding and ionisation processes is considered. The model also accommodates tDDIs involving inhibition of multiple transporters. Integrating prior in vitro information on the metabolism and transporter kinetics of rosuvastatin (organic-anion transporting polypeptides OATP1B1, OAT1B3 and OATP2B1, sodium-dependent taurocholate co-transporting polypeptide [NTCP] and breast cancer resistance protein [BCRP]) with one clinical dataset, the PBPK model was used to simulate the drug disposition of rosuvastatin for 11 reported studies that had not been used for development of the rosuvastatin model. The simulated area under the plasma concentration-time curve (AUC), maximum concentration (C max) and the time to reach C max (t max) values of rosuvastatin over the dose range of 10-80 mg, were within 2-fold of the observed data. Subsequently, the validated model was used to investigate the impact of

  9. Selection of organic chemicals for subsurface transport. Subsurface transport program interaction seminar series. Summary

    International Nuclear Information System (INIS)

    Zachara, J.M.; Wobber, F.J.

    1984-11-01

    Model compounds are finding increasing use in environmental research. These individual compounds are selected as surrogates of important contaminants present in energy/defense wastes and their leachates and are used separately or as mixtures in research to define the anticipated or ''model'' environmental behavior of key waste components and to probe important physicochemical mechanisms involved in transport and fate. A seminar was held in Germantown, Maryland, April 24-25, 1984 to discuss the nature of model organic compounds being used for subsurface transport research. The seminar included participants experienced in the fields of environmental chemistry, microbiology, geohydrology, biology, and analytic chemistry. The objectives of the seminar were two-fold: (1) to review the rationale for the selection of organic compounds adopted by research groups working on the subsurface transport of organics, and (2) to evaluate the use of individual compounds to bracket the behavior of compound classes and compound constructs to approximate the behavior of complex organic mixtures

  10. Evaluation of air-interfaced Calu-3 cell layers for investigation of inhaled drug interactions with organic cation transporters in vitro.

    Science.gov (United States)

    Mukherjee, Manali; Pritchard, D I; Bosquillon, C

    2012-04-15

    A physiologically pertinent in vitro model is urgently needed for probing interactions between inhaled drugs and the organic cation transporters (OCT) in the bronchial epithelium. This study evaluated OCT expression, functionality, inhibition by common inhaled drugs and impact on formoterol transepithelial transport in layers of human bronchial epithelial Calu-3 cells grown at an air-liquid interface. 21 day old Calu-3 layers expressed OCT1, OCT3, OCTN1 and OCTN2 whereas OCT2 could not be detected. Quantification of the cellular uptake of the OCT substrate ASP(+) in presence of inhibitors suggested several OCT were functional at the apical side of the cell layers. ASP(+) uptake was reduced by the bronchodilators formoterol, salbutamol (albuterol), ipratropium and the glucocorticoid budesonide. However, the OCT inhibitory properties of the two β(2)-mimetics were suppressed at therapeutically relevant concentrations. The absorptive permeability of formoterol across the cell layers was enhanced at a high drug concentration shown to decrease ASP(+) uptake by ∼50% as well as in presence of the OCT inhibitor tetraethylammonium (TEA). Secretory transport was unaffected by the drug concentration but was reduced by TEA. Our data indicate air-interfaced Calu-3 layers offer a low-cost in vitro model suitable for assessing inhaled drug-OCT interactions in the bronchial epithelium. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Transportation Institutional Plan

    Energy Technology Data Exchange (ETDEWEB)

    1986-08-01

    This Institutional Plan is divided into three chapters. Chapter 1 provides background information, discusses the purposes of the Plan and the policy guidance for establishing the transportation system, and describes the projected system and the plans for its integrated development. Chapter 2 discusses the major participants who must interact to build the system. Chapter 3 suggests mechanisms for interaction that will foster wide participation in program planning and implementation and provides a framework for managing and resolving the issues related to development and operation of the transportation system. A list of acronyms and a glossary are included for the reader's convenience. Also included in this Plan are four appendices. Of particular importance is Appendix A, which includes detailed discussion of specific transportation issues. Appendices B, C, and D provide supporting material to assist the reader in understanding the roles of the involved institutions.

  12. Interaction and transport of actinides in natural clay rock with consideration of humic substances and clay organic compounds

    International Nuclear Information System (INIS)

    Marquardt, C.M.

    2012-01-01

    The present report summarizes the progress and the results obtained within the BMWi financed Joint Research Project Interaction and Transport of Actinides in Natural Clay Rock with Consideration of Humic Substances and Clay Organic Compounds. The basic approach of the work was to obtain a fundamental process understanding on the molecular level of complexation and sorption reactions as well as diffusion processes. The experimental findings are supported by quantum mechanical modeling.

  13. Physical Interactions and Functional Relationships of Neuroligin 2 and Midbrain Serotonin Transporters

    Directory of Open Access Journals (Sweden)

    Ran eYe

    2016-01-01

    Full Text Available The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT modulates many key brain functions including those subserving sensation, emotion, reward and cognition. Efficient clearance of 5-HT after release is achieved by the antidepressant-sensitive 5-HT transporter (SERT, SLC6A4. To identify novel SERT regulators, we pursued a proteomic analysis of mouse midbrain SERT complexes, evaluating findings in the context of prior studies that established a SERT-linked transcriptome. Remarkably, both efforts converged on a relationship of SERT with the synaptic adhesion protein neuroligin 2 (NLGN2, a postsynaptic partner for presynaptic neurexins, and a protein well known to organize inhibitory GABAergic synapses. Western blots of midbrain reciprocal immunoprecipitations confirmed SERT/NLGN2 associations, and also extended to other NLGN2 associated proteins (e.g. -neurexin (NRXN, gephyrin. Midbrain SERT/NLGN2 interactions were found to be Ca2+-independent, supporting cis versus trans-synaptic interactions, and were absent in hippocampal preparations, consistent with interactions arising in somatodendritic compartments. Dual color in situ hybridization confirmed co-expression of Tph2 and Nlgn2 mRNA in the dorsal raphe, with immunocytochemical studies confirming SERT:NLGN2 co-localization in raphe cell bodies but not axons. Consistent with correlative mRNA expression studies, loss of NLGN2 expression in Nlgn2 null mice produced significant reductions in midbrain and hippocampal SERT expression and function. Additionally, dorsal raphe 5-HT neurons from Nlgn2 null mice exhibit reduced excitability, a loss of GABAA receptor-mediated IPSCs, and increased 5-HT1A autoreceptor sensitivity. Finally, Nlgn2 null mice display significant changes in behaviors known to be responsive to SERT and/or 5-HT receptor manipulations. We discuss our findings in relation to the possible coordination of intrinsic and extrinsic regulation afforded by somatodendritic SERT:NLGN2

  14. Transport and environmental sustainability: An adapted SPE approach for modelling interactions between transport, infrastructure, economy and environment

    Energy Technology Data Exchange (ETDEWEB)

    Verhoef, Erik; Van den Bergh, Jeroen [Department of Spatial Economics, Faculty of Economics and Econometrics, Free University Amsterdam, Amsterdam (Netherlands)

    1994-05-01

    The present paper aims at shedding some light on the concept of `sustainable transport`. Within the context of a sustainable development, the consequences of interdependencies between transport, infrastructure, economy and environment for the formulation of optimal regulatory policies are investigated. The Spatial Price Equilibrium approach is adapted for the analysis of sustainable spatio-economic development, and for the evaluation of first-best and second-best regulatory policies on the issues at hand. The analysis demonstrates the need for integration of elements concerning economic structure, infrastructure, transportation, environment and space in one single analytical framework when considering questions on sustainability in relation to transport. 2 figs., 1 appendix, 10 refs.

  15. Energy transport in dendrimers

    International Nuclear Information System (INIS)

    Supritz, C.; Engelmann, A.; Reineker, P.

    2006-01-01

    Dendrimers are highly branched polymers which are expected to be useful, for example, as efficient artificial light harvesting systems in nano-technological applications. There are two different classes of dendrimers: compact dendrimers with constant distance between neighboring branching points throughout the macromolecule and extended dendrimers where this distance increases from the system periphery to the center. An open question is still whether energy transport (via Frenkel excitons) occurs in a coherent or incoherent manner. We model the hyperbranched dendrimer molecule as an arrangement of two-level systems and apply the Frenkel exciton concept. The two-level systems are interacting with each other via transfer integrals modeling the special spatial structure of dendrimers. To take into account the electron-phonon interaction we introduce a heat bath that interacts with the exciton in a stochastic manner. In this way we describe the coupled coherent and incoherent Frenkel exciton transport inside a dendrimer. In order to mimic the influence of an energy capturing reaction center (like in photosynthesis) on exciton transport, we attach a sink to the dendrimer core

  16. Energy transport in dendrimers

    Energy Technology Data Exchange (ETDEWEB)

    Supritz, C. [Abteilung Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)]. E-mail: christoph.supritz@uni-ulm.de; Engelmann, A. [Abteilung Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany); Reineker, P. [Abteilung Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

    2006-07-15

    Dendrimers are highly branched polymers which are expected to be useful, for example, as efficient artificial light harvesting systems in nano-technological applications. There are two different classes of dendrimers: compact dendrimers with constant distance between neighboring branching points throughout the macromolecule and extended dendrimers where this distance increases from the system periphery to the center. An open question is still whether energy transport (via Frenkel excitons) occurs in a coherent or incoherent manner. We model the hyperbranched dendrimer molecule as an arrangement of two-level systems and apply the Frenkel exciton concept. The two-level systems are interacting with each other via transfer integrals modeling the special spatial structure of dendrimers. To take into account the electron-phonon interaction we introduce a heat bath that interacts with the exciton in a stochastic manner. In this way we describe the coupled coherent and incoherent Frenkel exciton transport inside a dendrimer. In order to mimic the influence of an energy capturing reaction center (like in photosynthesis) on exciton transport, we attach a sink to the dendrimer core.

  17. On the importance of aqueous diffusion and electrostatic interactions in advection-dominated transport in saturated porous media

    DEFF Research Database (Denmark)

    Rolle, Massimo

    2015-01-01

    to multicomponent ionic dispersion: the dispersive fluxes of the different ions are cross-coupled due to the effects of Coulombic interactions. Such effects are illustrated in flow-through experiments in saturated porous media. Simple strong electrolytes were selected as tracers and their transport was studied...... under different advection-dominated conditions and in homogeneous and heterogeneous porous media. The interpretation of the experimental results requires a multicomponent modeling approach with an accurate description of local hydrodynamic dispersion and explicitly accounting for the cross-coupling...

  18. Water transport through the intestinal epithelial barrier under different osmotic conditions is dependent on LI-cadherin trans-interaction.

    Science.gov (United States)

    Weth, Agnes; Dippl, Carsten; Striedner, Yasmin; Tiemann-Boege, Irene; Vereshchaga, Yana; Golenhofen, Nikola; Bartelt-Kirbach, Britta; Baumgartner, Werner

    2017-04-03

    In the intestine water has to be reabsorbed from the chymus across the intestinal epithelium. The osmolarity within the lumen is subjected to high variations meaning that water transport often has to take place against osmotic gradients. It has been hypothesized that LI-cadherin is important in this process by keeping the intercellular cleft narrow facilitating the buildup of an osmotic gradient allowing water reabsorption. LI-cadherin is exceptional among the cadherin superfamily with respect to its localization along the lateral plasma membrane of epithelial cells being excluded from adherens junction. Furthermore it has 7 but not 5 extracellular cadherin repeats (EC1-EC7) and a small cytosolic domain. In this study we identified the peptide VAALD as an inhibitor of LI-cadherin trans-interaction by modeling the structure of LI-cadherin and comparison with the known adhesive interfaces of E-cadherin. This inhibitory peptide was used to measure LI-cadherin dependency of water transport through a monolayer of epithelial CACO2 cells under various osmotic conditions. If LI-cadherin trans-interaction was inhibited by use of the peptide, water transport from the luminal to the basolateral side was impaired and even reversed in the case of hypertonic conditions whereas no effect could be observed at isotonic conditions. These data are in line with a recently published model predicting LI-cadherin to keep the width of the lateral intercellular cleft small. In this narrow cleft a high osmolarity can be achieved due to ion pumps yielding a standing osmotic gradient allowing water absorption from the gut even if the faeces is highly hypertonic.

  19. Interaction of environmental contaminants with zebrafish organic anion transporting polypeptide, Oatp1d1 (Slco1d1)

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, Marta; Zaja, Roko [Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb (Croatia); Fent, Karl [University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Swiss Federal Institute of Technology (ETH Zürich), Department of Environmental System Sciences, Institute of Biogeochemistry and Pollution Dynamics, CH-8092 Zürich (Switzerland); Smital, Tvrtko, E-mail: smital@irb.hr [Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb (Croatia)

    2014-10-01

    Polyspecific transporters from the organic anion transporting polypeptide (OATP/Oatp) superfamily mediate the uptake of a wide range of compounds. In zebrafish, Oatp1d1 transports conjugated steroid hormones and cortisol. It is predominantly expressed in the liver, brain and testes. In this study we have characterized the transport of xenobiotics by the zebrafish Oatp1d1 transporter. We developed a novel assay for assessing Oatp1d1 interactors using the fluorescent probe Lucifer yellow and transient transfection in HEK293 cells. Our data showed that numerous environmental contaminants interact with zebrafish Oatp1d1. Oatp1d1 mediated the transport of diclofenac with very high affinity, followed by high affinity towards perfluorooctanesulfonic acid (PFOS), nonylphenol, gemfibrozil and 17α-ethinylestradiol; moderate affinity towards carbaryl, diazinon and caffeine; and low affinity towards metolachlor. Importantly, many environmental chemicals acted as strong inhibitors of Oatp1d1. A strong inhibition of Oatp1d1 transport activity was found by perfluorooctanoic acid (PFOA), chlorpyrifos-methyl, estrone (E1) and 17β-estradiol (E2), followed by moderate to low inhibition by diethyl phthalate, bisphenol A, 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4 tetrahydronapthalene and clofibrate. In this study we identified Oatp1d1 as a first Solute Carrier (SLC) transporter involved in the transport of a wide range of xenobiotics in fish. Considering that Oatps in zebrafish have not been characterized before, our work on zebrafish Oatp1d1 offers important new insights on the understanding of uptake processes of environmental contaminants, and contributes to the better characterization of zebrafish as a model species. - Highlights: • We optimized a novel assay for determination of Oatp1d1 interactors • Oatp1d1 is the first SLC characterized fish xenobiotic transporter • PFOS, nonylphenol, diclofenac, EE2, caffeine are high affinity Oatp1d1substrates • PFOA, chlorpyrifos

  20. Interaction of environmental contaminants with zebrafish organic anion transporting polypeptide, Oatp1d1 (Slco1d1)

    International Nuclear Information System (INIS)

    Popovic, Marta; Zaja, Roko; Fent, Karl; Smital, Tvrtko

    2014-01-01

    Polyspecific transporters from the organic anion transporting polypeptide (OATP/Oatp) superfamily mediate the uptake of a wide range of compounds. In zebrafish, Oatp1d1 transports conjugated steroid hormones and cortisol. It is predominantly expressed in the liver, brain and testes. In this study we have characterized the transport of xenobiotics by the zebrafish Oatp1d1 transporter. We developed a novel assay for assessing Oatp1d1 interactors using the fluorescent probe Lucifer yellow and transient transfection in HEK293 cells. Our data showed that numerous environmental contaminants interact with zebrafish Oatp1d1. Oatp1d1 mediated the transport of diclofenac with very high affinity, followed by high affinity towards perfluorooctanesulfonic acid (PFOS), nonylphenol, gemfibrozil and 17α-ethinylestradiol; moderate affinity towards carbaryl, diazinon and caffeine; and low affinity towards metolachlor. Importantly, many environmental chemicals acted as strong inhibitors of Oatp1d1. A strong inhibition of Oatp1d1 transport activity was found by perfluorooctanoic acid (PFOA), chlorpyrifos-methyl, estrone (E1) and 17β-estradiol (E2), followed by moderate to low inhibition by diethyl phthalate, bisphenol A, 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4 tetrahydronapthalene and clofibrate. In this study we identified Oatp1d1 as a first Solute Carrier (SLC) transporter involved in the transport of a wide range of xenobiotics in fish. Considering that Oatps in zebrafish have not been characterized before, our work on zebrafish Oatp1d1 offers important new insights on the understanding of uptake processes of environmental contaminants, and contributes to the better characterization of zebrafish as a model species. - Highlights: • We optimized a novel assay for determination of Oatp1d1 interactors • Oatp1d1 is the first SLC characterized fish xenobiotic transporter • PFOS, nonylphenol, diclofenac, EE2, caffeine are high affinity Oatp1d1substrates • PFOA, chlorpyrifos

  1. Spin-orbit interaction induced anisotropic property in interacting quantum wires

    Directory of Open Access Journals (Sweden)

    Chang Kai

    2011-01-01

    Full Text Available We investigate theoretically the ground state and transport property of electrons in interacting quantum wires (QWs oriented along different crystallographic directions in (001 and (110 planes in the presence of the Rashba spin-orbit interaction (RSOI and Dresselhaus SOI (DSOI. The electron ground state can cross over different phases, e.g., spin density wave, charge density wave, singlet superconductivity, and metamagnetism, by changing the strengths of the SOIs and the crystallographic orientation of the QW. The interplay between the SOIs and Coulomb interaction leads to the anisotropic dc transport property of QW which provides us a possible way to detect the strengths of the RSOI and DSOI. PACS numbers: 73.63.Nm, 71.10.Pm, 73.23.-b, 71.70.Ej

  2. Divide and conquer: processive transport enables multidrug transporters to tackle challenging drugs

    Directory of Open Access Journals (Sweden)

    Nir Fluman

    2014-09-01

    Full Text Available Multidrug transporters are membrane proteins that catalyze efflux of antibiotics and other toxic compounds from cells, thereby conferring drug resistance on various organisms. Unlike most solute transporters that transport a single type of compound or similar analogues, multidrug transporters are extremely promiscuous. They transport a broad spectrum of dissimilar drugs and represent a serious obstacle to antimicrobial or anticancer chemotherapy. Many challenging aspects of multidrug transporters, which are unique, have been studied in detail, including their ability to interact with chemically unrelated drugs, and how they utilize energy to drive efflux of compounds that are not only structurally but electrically different. A new and surprising dimension of the promiscuous nature of multidrug transporters has been described recently: they can move long molecules through the membrane in a processive manner.

  3. Yeast Interacting Proteins Database: YNR051C, YER151C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available that coregulates anterograde and retrograde transport between the endoplasmic reticulum and Golgi compartme...C UBP3 Ubiquitin-specific protease that interacts with Bre5p to co-regulate anterograde and retrograde...t coregulates anterograde and retrograde transport between the endoplasmic reticulum and Golgi compartments;...3 Prey description Ubiquitin-specific protease that interacts with Bre5p to co-regulate anterograde and retrograde

  4. Transport, chaos and plasma physics

    International Nuclear Information System (INIS)

    Benkadda, S.; Doveil, F.; Elskens, Y.

    1993-01-01

    This workshop made it possible to gather for the first time plasma physicists, dynamical systems physicists and mathematicians, around a general theme focusing on the characterisation of chaotic transport. The participations have been divided into 4 topics: - dynamical systems and microscopic models of chaotic transport, - magnetic fluctuations and transport in tokamaks, - drift wave turbulence, self-organisation and intermittency, and - Wave-particle interactions

  5. Understanding transporter specificity and the discrete appearance of channel-like gating domains in transporters

    Directory of Open Access Journals (Sweden)

    GEORGE eDIALLINAS

    2014-09-01

    Full Text Available Transporters are ubiquitous proteins mediating the translocation of solutes across cell membranes, a biological process involved in nutrition, signaling, neurotransmission, cell communication and drug uptake or efflux. Similarly to enzymes, most transporters have a single substrate binding-site and thus their activity follows Michaelis-Menten kinetics. Substrate binding elicits a series of structural changes, which produce a transporter conformer open towards the side opposite to the one from where the substrate was originally bound. This mechanism, involving alternate outward- and inward-facing transporter conformers, has gained significant support from structural, genetic, biochemical and biophysical approaches. Most transporters are specific for a given substrate or a group of substrates with similar chemical structure, but substrate specificity and/or affinity can vary dramatically, even among members of a transporter family that show high overall amino acid sequence and structural similarity. The current view is that transporter substrate affinity or specificity is determined by a small number of interactions a given solute can make within a specific binding site. However, genetic, biochemical and in silico modeling studies with the purine transporter UapA of the filamentous ascomycete Aspergillus nidulans have challenged this dogma. This review highlights results leading to a novel concept, stating that substrate specificity, but also transport kinetics and transporter turnover, are determined by subtle intramolecular interactions between a major substrate binding site and independent outward- or cytoplasmically-facing gating domains, analogous to those present in channels. This concept is supported by recent structural evidence from several, phylogenetically and functionally distinct transporter families. The significance of this concept is discussed in relationship to the role and potential exploitation of transporters in drug action.

  6. Does prenatal valproate interact with a genetic reduction in the serotonin transporter?A rat study on anxiety and cognition

    Directory of Open Access Journals (Sweden)

    Bart A Ellenbroek

    2016-09-01

    Full Text Available There is ample evidence that prenatal exposure to valproate (or valproic acid, VPA enhances the risk of developing Autism Spectrum Disorders (ASD. In line with this, a single injection of VPA induces a multitude of ASD-like symptoms in animals such as rats and mice. However, there is equally strong evidence that genetic factors contribute significantly to the risk of ASD and indeed, like most other psychiatric disorders, ASD is now generally thought to results from an interaction between genetic and environmental factors. Given that VPA significantly impacts on the serotonergic system, and serotonin has strong biochemical and genetic links to ASD, we aimed to investigate the interaction between genetic reduction in the serotonin transporter and prenatal valproate administration. More specifically, we exposed both wildtype (SERT+/+ rats and rats heterozygous for the serotonin transporter deletion (SERT+/- to a single injection of 400 mg/kg VPA at gestational day (GD 12. The offspring, in adulthood, was assessed in four different tests: Elevated Plus Maze and Novelty Suppressed Feeding as measures for anxiety and prepulse inhibition (PPI and latent inhibition as measures for cognition and information processing. The results show that prenatal VPA significantly increased anxiety in both paradigm, reduced PPI and reduced conditioning in the latent inhibition paradigm. However, we failed to find a significant gene – environment interaction. We propose that this may be related to the timing of the VPA injection and suggest that whereas GD12 might be optimal for affecting normal rat, rats with a genetically compromised serotonergic system may be more sensitive to VPA at earlier time points during gestation. Overall our data are the first to investigate gene * environmental interactions in a genetic rat model for ASD suggest that timing may be of crucial importance to the long-term outcome.

  7. Draft Transportation Institutional Plan

    International Nuclear Information System (INIS)

    1985-09-01

    The Department of Energy recognizes that the success of its program to develop and implement a national system for nuclear waste management and disposal depends on broad-based public understanding and acceptance. While each program element has its particular sensitivity, the transportation of the waste may potentially affect the greatest number of people, and accordingly is highly visible and potentially issue-laden. Therefore, the Office of Civilian Radioactive Waste Management has developed this Transportation Institutional Plan to lay the foundation for interaction among all interested parties for the purpose of identifying and resolving issues of concern. The Plan is divided into four chapters. Chapter 1 provides bachground information and discusses the purpose of the Plan and the policy guidance for establishing the transportation system. Chapter 2 introduces the major participants who must interact to build both the system itself and the consensus philosophy that is essential for effective operations. Chapter 3 suggests mechanisms for interaction that will ensure wide participation in program planning and implementation. And, finally, Chapter 4 suggests a framework for managing and resolving the issues related to development and operation of the transportation system. A list of acronyms and a glossary are included for the reader's convenience. The Plan's appendices provide supporting material to assist the reader in understanding the roles of the involved institutions. 4 figs., 1 tab

  8. Micron-scale mapping of megagauss magnetic fields using optical polarimetry to probe hot electron transport in petawatt-class laser-solid interactions.

    Science.gov (United States)

    Chatterjee, Gourab; Singh, Prashant Kumar; Robinson, A P L; Blackman, D; Booth, N; Culfa, O; Dance, R J; Gizzi, L A; Gray, R J; Green, J S; Koester, P; Kumar, G Ravindra; Labate, L; Lad, Amit D; Lancaster, K L; Pasley, J; Woolsey, N C; Rajeev, P P

    2017-08-21

    The transport of hot, relativistic electrons produced by the interaction of an intense petawatt laser pulse with a solid has garnered interest due to its potential application in the development of innovative x-ray sources and ion-acceleration schemes. We report on spatially and temporally resolved measurements of megagauss magnetic fields at the rear of a 50-μm thick plastic target, irradiated by a multi-picosecond petawatt laser pulse at an incident intensity of ~10 20 W/cm 2 . The pump-probe polarimetric measurements with micron-scale spatial resolution reveal the dynamics of the magnetic fields generated by the hot electron distribution at the target rear. An annular magnetic field profile was observed ~5 ps after the interaction, indicating a relatively smooth hot electron distribution at the rear-side of the plastic target. This is contrary to previous time-integrated measurements, which infer that such targets will produce highly structured hot electron transport. We measured large-scale filamentation of the hot electron distribution at the target rear only at later time-scales of ~10 ps, resulting in a commensurate large-scale filamentation of the magnetic field profile. Three-dimensional hybrid simulations corroborate our experimental observations and demonstrate a beam-like hot electron transport at initial time-scales that may be attributed to the local resistivity profile at the target rear.

  9. Mathematical foundations of transport theory

    International Nuclear Information System (INIS)

    Ershov, Yu.I.; Shikhov, S.B.

    1985-01-01

    Foundations of mathematical transport theory are presented. Definitions and theorems of functional analysis are given. Linear kinetic equation of neutron transport in multiplication media is derived. A model of neutron interaction with nuclei of medium determining completely the coefficient properties in transport equation is described. Non-stationary problems regarding and without regard of d=e layed neutrons are analyzed. Results of solving Cauchy problem are discussed

  10. Dossier: transport of radioactive materials; Dossier: le transport des matieres radioactives

    Energy Technology Data Exchange (ETDEWEB)

    Mignon, H. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Direction du Cycle du Combustible; Niel, J.Ch. [CEA Centre d`Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire; Canton, H. [CEA Cesta, 33 - Bordeaux (France); Brachet, Y. [Transnucleaire, 75 - Paris (France); Turquet de Beauregard, G.; Mauny, G. [CIS bio international, France (France); Robine, F.; Plantet, F. [Prefecture de la Moselle (France); Pestel Lefevre, O. [Ministere de l`Equipement, des transports et du logement, (France); Hennenhofer, G. [BMU, Ministere de l`environnement, de la protection de la nature et de la surete des reacteurs (Germany); Bonnemains, J. [Association Robin des Bois (France)

    1997-12-01

    This dossier is entirely devoted to the transportation of radioactive and fissile materials of civil use. It comprises 9 papers dealing with: the organization of the control of the radioactive materials transport safety (safety and security aspects, safety regulations, safety analysis and inspection, emergency plans, public information), the technical aspects of the regulation concerning the transport of radioactive materials (elaboration of regulations and IAEA recommendations, risk assessments, defense in depth philosophy and containers, future IAEA recommendations, expertise-research interaction), the qualification of containers (regulations, test facilities), the Transnucleaire company (presentation, activity, containers for spent fuels), the packages of radioactive sources for medical use (flux, qualification, safety and transport), an example of accident during radioactive materials transportation: the Apach train derailment (February 4, 1997), the sea transport of radioactive materials (international maritime organization (OMI), international maritime dangerous goods (IMDG) code, irradiated nuclear fuel (INF) safety rules), the transport of radioactive materials in Germany, and the point of view from an external observer. (J.S.)

  11. The interaction of the flux errors and transport errors in modeled atmospheric carbon dioxide concentrations

    Science.gov (United States)

    Feng, S.; Lauvaux, T.; Butler, M. P.; Keller, K.; Davis, K. J.; Jacobson, A. R.; Schuh, A. E.; Basu, S.; Liu, J.; Baker, D.; Crowell, S.; Zhou, Y.; Williams, C. A.

    2017-12-01

    Regional estimates of biogenic carbon fluxes over North America from top-down atmospheric inversions and terrestrial biogeochemical (or bottom-up) models remain inconsistent at annual and sub-annual time scales. While top-down estimates are impacted by limited atmospheric data, uncertain prior flux estimates and errors in the atmospheric transport models, bottom-up fluxes are affected by uncertain driver data, uncertain model parameters and missing mechanisms across ecosystems. This study quantifies both flux errors and transport errors, and their interaction in the CO2 atmospheric simulation. These errors are assessed by an ensemble approach. The WRF-Chem model is set up with 17 biospheric fluxes from the Multiscale Synthesis and Terrestrial Model Intercomparison Project, CarbonTracker-Near Real Time, and the Simple Biosphere model. The spread of the flux ensemble members represents the flux uncertainty in the modeled CO2 concentrations. For the transport errors, WRF-Chem is run using three physical model configurations with three stochastic perturbations to sample the errors from both the physical parameterizations of the model and the initial conditions. Additionally, the uncertainties from boundary conditions are assessed using four CO2 global inversion models which have assimilated tower and satellite CO2 observations. The error structures are assessed in time and space. The flux ensemble members overall overestimate CO2 concentrations. They also show larger temporal variability than the observations. These results suggest that the flux ensemble is overdispersive. In contrast, the transport ensemble is underdispersive. The averaged spatial distribution of modeled CO2 shows strong positive biogenic signal in the southern US and strong negative signals along the eastern coast of Canada. We hypothesize that the former is caused by the 3-hourly downscaling algorithm from which the nighttime respiration dominates the daytime modeled CO2 signals and that the latter

  12. Economic crisis and its influences on the interaction between land use and transport in Madrid Region

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.

    2016-07-01

    The road transport system is closely linked to the land-use system. The road system connects territories at all spatial scale, on the other hand, passengers and freight travel behavior are strongly influenced both by land-use and the road transport system. Hence, research in the field of the interactions between land-use and the road transport system is still less, particular the influence of the economic crisis. This paper aims to find out if the statistical analysis of land use and mobility can help to answer the question of what happens during economic crisis on both land use and transport system, and unveiling key spatial relationships between them. The methodology for the analysis was developed accordingly with the data and resources available. First, an exploratory data analysis (EDA) is performed in order to identify the land use and mobility pattern during the last decade. This analysis focuses on six aspects, which are distribution of population and dwellings, employment and jobs, GDP, motorization and modal split. The second aspect consists on crossing the spatial patterns of the different aspects in order to find some explanatory relationships that indicate the presence of the key characteristics. The analysis is based on the case of Madrid Region. The land-use and transport data presented in this analysis are from 2004 to 2014, which are collected from the national statistical institute, the regional government database and two urban mobility surveys of Madrid. Through the exploration analysis, we find that there is close relationship between the land-use system and travel behavior in Madrid Region. With an increasing of new dwellings constructed in the outer periphery of Madrid Region, it leads longer trips distance and more travel cost particularly by car mode. Moreover, during the economic crisis, we also find the motorization level of Madrid keeps the same, as a result of the decreasing GDP and relatively decreasing. (Author)

  13. Advanced methods for the computation of particle beam transport and the computation of electromagnetic fields and beam-cavity interactions

    International Nuclear Information System (INIS)

    Dragt, A.J.; Gluckstern, R.L.

    1992-11-01

    The University of Maryland Dynamical Systems and Accelerator Theory Group carries out research in two broad areas: the computation of charged particle beam transport using Lie algebraic methods and advanced methods for the computation of electromagnetic fields and beam-cavity interactions. Important improvements in the state of the art are believed to be possible in both of these areas. In addition, applications of these methods are made to problems of current interest in accelerator physics including the theoretical performance of present and proposed high energy machines. The Lie algebraic method of computing and analyzing beam transport handles both linear and nonlinear beam elements. Tests show this method to be superior to the earlier matrix or numerical integration methods. It has wide application to many areas including accelerator physics, intense particle beams, ion microprobes, high resolution electron microscopy, and light optics. With regard to the area of electromagnetic fields and beam cavity interactions, work is carried out on the theory of beam breakup in single pulses. Work is also done on the analysis of the high frequency behavior of longitudinal and transverse coupling impedances, including the examination of methods which may be used to measure these impedances. Finally, work is performed on the electromagnetic analysis of coupled cavities and on the coupling of cavities to waveguides

  14. Surface targeting of the dopamine transporter involves discrete epitopes in the distal C terminus but does not require canonical PDZ domain interactions.

    Science.gov (United States)

    Bjerggaard, Christian; Fog, Jacob U; Hastrup, Hanne; Madsen, Kenneth; Loland, Claus J; Javitch, Jonathan A; Gether, Ulrik

    2004-08-04

    The human dopamine transporter (hDAT) contains a C-terminal type 2 PDZ (postsynaptic density 95/Discs large/zona occludens 1) domain-binding motif (LKV) known to interact with PDZ domain proteins such as PICK1 (protein interacting with C-kinase 1). As reported previously, we found that, after deletion of this motif, hDAT was retained in the endoplasmic reticulum (ER) of human embryonic kidney (HEK) 293 and Neuro2A cells, suggesting that PDZ domain interactions might be critical for hDAT targeting. Nonetheless, substitution of LKV with SLL, the type 1 PDZ-binding sequence from the beta2-adrenergic receptor, did not disrupt plasma membrane targeting. Moreover, the addition of an alanine to the hDAT C terminus (+Ala), resulting in an LKVA termination sequence, or substitution of LKV with alanines (3xAla_618-620) prevented neither plasma membrane targeting nor targeting into sprouting neurites of differentiated N2A cells. The inability of +Ala and 3xAla_618-620 to bind PDZ domains was confirmed by lack of colocalization with PICK1 in cotransfected HEK293 cells and by the inability of corresponding C-terminal fusion proteins to pull down purified PICK1. Thus, although residues in the hDAT C terminus are indispensable for proper targeting, PDZ domain interactions are not required. By progressive substitutions with beta2-adrenergic receptor sequence, and by triple-alanine substitutions in the hDAT C terminus, we examined the importance of epitopes preceding the LKV motif. Substitution of RHW(615-617) with alanines caused retention of the transporter in the ER despite preserved ability of this mutant to bind PICK1. We propose dual roles of the hDAT C terminus: a role independent of PDZ interactions for ER export and surface targeting, and a not fully clarified role involving PDZ interactions with proteins such as PICK1.

  15. Interactive Design of Accelerators (IDA)

    International Nuclear Information System (INIS)

    Barton, M.Q.

    1987-01-01

    IDA is a beam transport line calculation program which runs interactively on an IBM PC computer. It can be used for a large fraction of the usual calculations done for beam transport systems or periods of accelerators or storage rings. Because of the interactive screen editor nature of the data input, this program permits one to rather quickly arrive at general properties of a beam line or an accelerator period

  16. Variations in periplasmic loop interactions determine the pH-dependent activity of the hexameric urea transporter UreI from Helicobacter pylori: a molecular dynamics study.

    Science.gov (United States)

    Cáceres-Delpiano, Javier; Teneb, Jaime; Mansilla, Rodrigo; García, Apolinaria; Salas-Burgos, Alexis

    2015-06-26

    Helicobacter pylori is an important factor in the development of diseases such as ulcer and gastric cancer. This bacterium uses a periplasmic transporter, UreI, to deliver urea to the intracelullar space, where later it is transformed into ammonia by the cytoplasmic enzyme urease to survive the acidic condition of the human stomach. The UreI transporter presents a pH-dependent activity, where this pH-dependence remains unknown at a structural level. Althought the existance of several protonable residues in the periplasmic loops are related to the pH-dependent activity, we find interesting to have a clear view of the conformational changes involved in this phenomena through a molecular dynamic study. Molecular dynamic simulations of the UreI transporter at three different pH conditions were performed, revealing two main pH-dependent conformations, which we present as the open and close states. We find that salt bridges between the periplasmic loops are crucial interactions that stabilize these conformations. Besides, a cooperative behaviour exists between the six subunits of the system that is necessary to fulfill the activity of this transporter. We found different pH-dependent conformations of the urea transporter UreI from Helicobacter pylori, which are related to salt-bridge interactions in the periplasmic regions. The behaviour of every channel in the system is not independent, given the existance of a cooperative behaviour through the formation of salt-bridges between the subunits of the hexameric system. We believe that our results will be related to the generation of new eradication therapies using this transporter as an attractive target, denoting that the knowledge of the possible pH-dependent conformations adopted for this transporter are important for the development of rational drug design approximations.

  17. Evaluation of transporters in drug development: Current status and contemporary issues.

    Science.gov (United States)

    Lee, Sue-Chih; Arya, Vikram; Yang, Xinning; Volpe, Donna A; Zhang, Lei

    2017-07-01

    Transporters govern the access of molecules to cells or their exit from cells, thereby controlling the overall distribution of drugs to their intracellular site of action. Clinically relevant drug-drug interactions mediated by transporters are of increasing interest in drug development. Drug transporters, acting alone or in concert with drug metabolizing enzymes, can play an important role in modulating drug absorption, distribution, metabolism and excretion, thus affecting the pharmacokinetics and/or pharmacodynamics of a drug. The drug interaction guidance documents from regulatory agencies include various decision criteria that may be used to predict the need for in vivo assessment of transporter-mediated drug-drug interactions. Regulatory science research continues to assess the prediction performances of various criteria as well as to examine the strength and limitations of each prediction criterion to foster discussions related to harmonized decision criteria that may be used to facilitate global drug development. This review discusses the role of transporters in drug development with a focus on methodologies in assessing transporter-mediated drug-drug interactions, challenges in both in vitro and in vivo assessments of transporters, and emerging transporter research areas including biomarkers, assessment of tissue concentrations, and effect of diseases on transporters. Published by Elsevier B.V.

  18. Spin transport in intermediate-energy heavy-ion collisions as a probe of in-medium spin–orbit interactions

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yin [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xu, Jun, E-mail: xujun@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li, Bao-An [Department of Physics and Astronomy, Texas A& M University-Commerce, Commerce, TX 75429-3011 (United States); Department of Applied Physics, Xi' an Jiao Tong University, Xi' an 710049 (China); Shen, Wen-Qing [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-11-15

    The spin up-down splitting of collective flows in intermediate-energy heavy-ion collisions as a result of the nuclear spin–orbit interaction is investigated within a spin- and isospin-dependent Boltzmann–Uehling–Uhlenbeck transport model SIBUU12. Using a Skyrme-type spin–orbit coupling quadratic in momentum, we found that the spin splittings of the directed flow and elliptic flow are largest in peripheral Au+Au collisions at beam energies of about 100–200 MeV/nucleon, and the effect is considerable even in smaller systems especially for nucleons with high transverse momenta. The collective flows of light clusters of different spin states are also investigated using an improved dynamical coalescence model with spin. Our study can be important in understanding the properties of in-medium nuclear spin–orbit interactions once the spin-dependent observables proposed in this work can be measured.

  19. The use of Monte Carlo radiation transport codes in radiation physics and dosimetry

    CERN Multimedia

    CERN. Geneva; Ferrari, Alfredo; Silari, Marco

    2006-01-01

    Transport and interaction of electromagnetic radiation Interaction models and simulation schemes implemented in modern Monte Carlo codes for the simulation of coupled electron-photon transport will be briefly reviewed. In these codes, photon transport is simulated by using the detailed scheme, i.e., interaction by interaction. Detailed simulation is easy to implement, and the reliability of the results is only limited by the accuracy of the adopted cross sections. Simulations of electron and positron transport are more difficult, because these particles undergo a large number of interactions in the course of their slowing down. Different schemes for simulating electron transport will be discussed. Condensed algorithms, which rely on multiple-scattering theories, are comparatively fast, but less accurate than mixed algorithms, in which hard interactions (with energy loss or angular deflection larger than certain cut-off values) are simulated individually. The reliability, and limitations, of electron-interacti...

  20. Effect of External Electric Field on Substrate Transport of a Secondary Active Transporter.

    Science.gov (United States)

    Zhang, Ji-Long; Zheng, Qing-Chuan; Yu, Li-Ying; Li, Zheng-Qiang; Zhang, Hong-Xing

    2016-08-22

    Substrate transport across a membrane accomplished by a secondary active transporter (SAT) is essential to the normal physiological function of living cells. In the present research, a series of all-atom molecular dynamics (MD) simulations under different electric field (EF) strengths was performed to investigate the effect of an external EF on the substrate transport of an SAT. The results show that EF both affects the interaction between substrate and related protein's residues by changing their conformations and tunes the timeline of the transport event, which collectively reduces the height of energy barrier for substrate transport and results in the appearance of two intermediate conformations under the existence of an external EF. Our work spotlights the crucial influence of external EFs on the substrate transport of SATs and could provide a more penetrating understanding of the substrate transport mechanism of SATs.

  1. Holographic interaction effects on transport in Dirac semimetals

    NARCIS (Netherlands)

    Jacobs, V.P.J.; Vandoren, S.; Stoof, H.T.C.

    2014-01-01

    Strongly interacting Dirac semimetals are investigated using a holographic model especially geared to compute the single-particle correlation function for this case, including both interaction effects and non-zero temperature. We calculate the (homogeneous) optical conductivity at zero chemical

  2. Development of novel, 384-well high-throughput assay panels for human drug transporters: drug interaction and safety assessment in support of discovery research.

    Science.gov (United States)

    Tang, Huaping; Shen, Ding Ren; Han, Yong-Hae; Kong, Yan; Balimane, Praveen; Marino, Anthony; Gao, Mian; Wu, Sophie; Xie, Dianlin; Soars, Matthew G; O'Connell, Jonathan C; Rodrigues, A David; Zhang, Litao; Cvijic, Mary Ellen

    2013-10-01

    Transporter proteins are known to play a critical role in affecting the overall absorption, distribution, metabolism, and excretion characteristics of drug candidates. In addition to efflux transporters (P-gp, BCRP, MRP2, etc.) that limit absorption, there has been a renewed interest in influx transporters at the renal (OATs, OCTs) and hepatic (OATPs, BSEP, NTCP, etc.) organ level that can cause significant clinical drug-drug interactions (DDIs). Several of these transporters are also critical for hepatobiliary disposition of bilirubin and bile acid/salts, and their inhibition is directly implicated in hepatic toxicities. Regulatory agencies took action to address transporter-mediated DDI with the goal of ensuring drug safety in the clinic and on the market. To meet regulatory requirements, advanced bioassay technology and automation solutions were implemented for high-throughput transporter screening to provide structure-activity relationship within lead optimization. To enhance capacity, several functional assay formats were miniaturized to 384-well throughput including novel fluorescence-based uptake and efflux inhibition assays using high-content image analysis as well as cell-based radioactive uptake and vesicle-based efflux inhibition assays. This high-throughput capability enabled a paradigm shift from studying transporter-related issues in the development space to identifying and dialing out these concerns early on in discovery for enhanced mechanism-based efficacy while circumventing DDIs and transporter toxicities.

  3. Quantitative measurements and modeling of cargo–motor interactions during fast transport in the living axon

    International Nuclear Information System (INIS)

    Seamster, Pamela E; Loewenberg, Michael; Pascal, Jennifer; Chauviere, Arnaud; Gonzales, Aaron; Cristini, Vittorio; Bearer, Elaine L

    2012-01-01

    The kinesins have long been known to drive microtubule-based transport of sub-cellular components, yet the mechanisms of their attachment to cargo remain a mystery. Several different cargo-receptors have been proposed based on their in vitro binding affinities to kinesin-1. Only two of these—phosphatidyl inositol, a negatively charged lipid, and the carboxyl terminus of the amyloid precursor protein (APP-C), a trans-membrane protein—have been reported to mediate motility in living systems. A major question is how these many different cargo, receptors and motors interact to produce the complex choreography of vesicular transport within living cells. Here we describe an experimental assay that identifies cargo–motor receptors by their ability to recruit active motors and drive transport of exogenous cargo towards the synapse in living axons. Cargo is engineered by derivatizing the surface of polystyrene fluorescent nanospheres (100 nm diameter) with charged residues or with synthetic peptides derived from candidate motor receptor proteins, all designed to display a terminal COOH group. After injection into the squid giant axon, particle movements are imaged by laser-scanning confocal time-lapse microscopy. In this report we compare the motility of negatively charged beads with APP-C beads in the presence of glycine-conjugated non-motile beads using new strategies to measure bead movements. The ensuing quantitative analysis of time-lapse digital sequences reveals detailed information about bead movements: instantaneous and maximum velocities, run lengths, pause frequencies and pause durations. These measurements provide parameters for a mathematical model that predicts the spatiotemporal evolution of distribution of the two different types of bead cargo in the axon. The results reveal that negatively charged beads differ from APP-C beads in velocity and dispersion, and predict that at long time points APP-C will achieve greater progress towards the presynaptic

  4. Logistics and Transport - a conceptual model

    DEFF Research Database (Denmark)

    Jespersen, Per Homann; Drewes, Lise

    2004-01-01

    This paper describes how the freight transport sector is influenced by logistical principles of production and distribution. It introduces new ways of understanding freight transport as an integrated part of the changing trends of mobility. By introducing a conceptual model for understanding...... the interaction between logistics and transport, it points at ways to over-come inherent methodological difficulties when studying this relation...

  5. Interaction with the 5D3 monoclonal antibody is regulated by intramolecular rearrangements but not by covalent dimer formation of the human ABCG2 multidrug transporter

    DEFF Research Database (Denmark)

    Özvegy-Laczka, Csilla; Laczkó, Rozália; Hegedűs, Csilla

    2008-01-01

    D3 monoclonal antibody shows a function-dependent reactivity to an extracellular epitope of the ABCG2 transporter. In the current experiments we have further characterized the 5D3-ABCG2 interaction. The effect of chemical cross-linking and the modulation of extracellular S-S bridges...... on the transporter function and 5D3 reactivity of ABCG2 were investigated in depth. We found that several protein cross-linkers greatly increased 5D3 labeling in ABCG2 expressing HEK cells; however, there was no correlation between covalent dimer formation, the inhibition of transport activity, and the increase in 5...

  6. CHARLES HORTON COOLEY'S THEORY OF TRANSPORTATION: TOWARDS AN INTERACTIONIST APPROACH FOR TRANSPORTATION STUDIES

    Science.gov (United States)

    Nakano, Takeshi

    The aim of this paper is to interpret Charles Horton Cooley's "Theory of Transportation", situating it in his interactionist sociology of communication and social process. Cooley defines transportation as a spatial and physical form of communication. He also develops a interactionist theory of valuation and articulates that value as an end of action is shaped an d transformed by communication and interaction. These insights suggest that transportation as a form of communication will change and develop economic society through transforming personal desires and values so as to change behaviours. Cooley's theory implies that an interactionist approach is useful for understanding the subjective side of phenomena of transportation.

  7. Adolescent Loneliness and the Interaction between the Serotonin Transporter Gene (5-HTTLPR and Parental Support: A Replication Study.

    Directory of Open Access Journals (Sweden)

    Annette W M Spithoven

    Full Text Available Gene-by-environment interaction (GxEs studies have gained popularity over the last decade, but the robustness of such observed interactions has been questioned. The current study contributes to this debate by replicating the only study on the interaction between the serotonin transporter gene (5-HTTLPR and perceived parental support on adolescents' peer-related loneliness. A total of 1,111 adolescents (51% boys with an average age of 13.70 years (SD = 0.93 participated and three annual waves of data were collected. At baseline, adolescent-reported parental support and peer-related loneliness were assessed and genetic information was collected. Assessment of peer-related loneliness was repeated at Waves 2 and 3. Using a cohort-sequential design, a Latent Growth Curve Model was estimated. Overall, a slight increase of loneliness over time was found. However, the development of loneliness over time was found to be different for boys and girls: girls' levels of loneliness increased over time, whereas boys' levels of loneliness decreased. Parental support was inversely related to baseline levels of loneliness, but unrelated to change of loneliness over time. We were unable to replicate the main effect of 5-HTTLPR or the 5-HTTLPR x Support interaction effect. In the Discussion, we examine the implications of our non-replication.

  8. Functional interaction between CFTR and the sodium-phosphate co-transport type 2a in Xenopus laevis oocytes.

    Directory of Open Access Journals (Sweden)

    Naziha Bakouh

    Full Text Available A growing number of proteins, including ion transporters, have been shown to interact with Cystic Fibrosis Transmembrane conductance Regulator (CFTR. CFTR is an epithelial chloride channel that is involved in Cystic Fibrosis (CF when mutated; thus a better knowledge of its functional interactome may help to understand the pathophysiology of this complex disease. In the present study, we investigated if CFTR and the sodium-phosphate co-transporter type 2a (NPT2a functionally interact after heterologous expression of both proteins in Xenopus laevis oocytes.NPT2a was expressed alone or in combination with CFTR in X. laevis oocytes. Using the two-electrode voltage-clamp technique, the inorganic phosphate-induced current (IPi was measured and taken as an index of NPT2a activity. The maximal IPi for NPT2a substrates was reduced when CFTR was co-expressed with NPT2a, suggesting a decrease in its expression at the oolemna. This was consistent with Western blot analysis showing reduced NPT2a plasma membrane expression in oocytes co-expressing both proteins, whereas NPT2a protein level in total cell lysate was the same in NPT2a- and NPT2a+CFTR-oocytes. In NPT2a+CFTR- but not in NPT2a-oocytes, IPi and NPT2a surface expression were increased upon PKA stimulation, whereas stimulation of Exchange Protein directly Activated by cAMP (EPAC had no effect. When NPT2a-oocytes were injected with NEG2, a short amino-acid sequence from the CFTR regulatory domain that regulates PKA-dependent CFTR trafficking to the plasma membrane, IPi values and NPT2a membrane expression were diminished, and could be enhanced by PKA stimulation, thereby mimicking the effects of CFTR co-expression.We conclude that when both CFTR and NPT2a are expressed in X. laevis oocytes, CFTR confers to NPT2a a cAMPi-dependent trafficking to the membrane. This functional interaction raises the hypothesis that CFTR may play a role in phosphate homeostasis.

  9. Early life adversity and serotonin transporter gene variation interact at the level of the adrenal gland to affect the adult hypothalamo-pituitary-adrenal axis

    NARCIS (Netherlands)

    Doelen, R.H.A. van der; Deschamps, W.; D'Annibale, C.; Peeters, D.; Wevers, R.A.; Zelena, D.; Homberg, J.R.; Kozicz, L.T.

    2014-01-01

    The short allelic variant of the serotonin transporter (5-HTT) promoter-linked polymorphic region (5-HTTLPR) has been associated with the etiology of major depression by interaction with early life stress (ELS). Furthermore, 5-HTTLPR has been associated with abnormal functioning of the

  10. Structure-affinity relationship in the interactions of human organic anion transporter 1 with caffeine, theophylline, theobromine and their metabolites.

    Science.gov (United States)

    Sugawara, Mitsuru; Mochizuki, Takahiro; Takekuma, Yoh; Miyazaki, Katsumi

    2005-08-15

    It is well known that human organic anion transporter 1 (hOAT1) transports many kinds of drugs, endogenous compounds, and toxins. However, little is known about the structure-affinity relationship. The aim of this study was to elucidate the structure-affinity relationship using a series of structurally related compounds that interact with hOAT1. Inhibitory effects of xanthine- and uric acid-related compounds on the transport of p-aminohippuric acid were examined using CHO-K1 cells stably expressing hOAT1. The order of potency for the inhibitory effects of xanthine-related compounds on PAH uptake was 1-methyl derivative>7-methyl derivative>3-methyl derivative falling dotsxanthine>1,3,7-trimethyl derivative (caffeine). The order of potency of the inhibition was 1,3,7-trimethyluric acid>1,3-dimethyluric acid>1,7-dimethyluric acid>1-methyluric acid>uric acid. A significant correlation between inhibitory potency and lipophilicity of the tested uric acid-related compounds was observed. The main determinant of the affinity of xanthine-related compounds is the position of the methyl group. On the other hand, lipophilicity is the main determinant of the affinity of uric acid-related compounds.

  11. Natural polyphenols: Influence on membrane transporters

    Directory of Open Access Journals (Sweden)

    Saad Abdulrahman Hussain

    2016-03-01

    Full Text Available Accumulated evidences have focused on the use of natural polyphenolic compounds as nutraceuticals, since they showed a wide range of bioactivities and exhibited protection against variety of age related disorders. Polyphenols have variable potencies to interact, and hence alter the activities of various transporter proteins, many of them classified as ATP-Binding Cassette transporters, like multidrug resistance protein (MDRP, and p-glycoprotein (P-gp. Some of the efflux transporters are generally linked with anticancer and antiviral drug resistance; in this context, polyphenols may be beneficial in modulating drug resistance by increasing the efficacy of anticancer and antiviral drugs. Additionally, these effects were implicated to explain the influence of dietary polyphenols on drug efficacy as result of food-drug interactions. However, limited data are available about the influence of these components on uptake transporters. Therefore, the objective of this article is to review the potential efficacies of polyphenols in modulating the functional integrity of uptake transporter proteins, including those terminated the effect of neurotransmitters, and their possible influence in neuropharmacology. [J Complement Med Res 2016; 5(1.000: 97-104

  12. Experimental investigation of the impact of compound-specific dispersion and electrostatic interactions on transient transport and solute breakthrough

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Rolle, Massimo

    2017-01-01

    . The experimental results show that compound-specific effects and charge-induced Coulombic interactions are important not only at low velocities and/or for steady state plumes but also for transient transport under high flow velocities. Such effects can lead to a remarkably different behavior of measured....... The latter is based on the multicomponent formulation of coupled diffusive/dispersive fluxes and was used to describe and explain the electrostatic effects of charged species. Furthermore, we determined experimentally the temporal profiles of the flux-related dilution index. This metric of mixing, used...

  13. Co-evolution of transportation and land use : modeling historical dependencies in land use and transportation decision making.

    Science.gov (United States)

    2009-11-01

    The interaction between land use and transportation has long been the central issue in urban and regional planning. Models of such : interactions provide vital information to support many public policy decisions, such as land supply, infrastructure p...

  14. Interacting effects of discharge and channel morphology on transport of semibuoyant fish eggs in large, altered river systems.

    Directory of Open Access Journals (Sweden)

    Thomas A Worthington

    Full Text Available Habitat fragmentation and flow regulation are significant factors related to the decline and extinction of freshwater biota. Pelagic-broadcast spawning cyprinids require moving water and some length of unfragmented stream to complete their life cycle. However, it is unknown how discharge and habitat features interact at multiple spatial scales to alter the transport of semi-buoyant fish eggs. Our objective was to assess the relationship between downstream drift of semi-buoyant egg surrogates (gellan beads and discharge and habitat complexity. We quantified transport time of a known quantity of beads using 2-3 sampling devices at each of seven locations on the North Canadian and Canadian rivers. Transport time was assessed based on median capture time (time at which 50% of beads were captured and sampling period (time period when 2.5% and 97.5% of beads were captured. Habitat complexity was assessed by calculating width∶depth ratios at each site, and several habitat metrics determined using analyses of aerial photographs. Median time of egg capture was negatively correlated to site discharge. The temporal extent of the sampling period at each site was negatively correlated to both site discharge and habitat-patch dispersion. Our results highlight the role of discharge in driving transport times, but also indicate that higher dispersion of habitat patches relates to increased retention of beads within the river. These results could be used to target restoration activities or prioritize water use to create and maintain habitat complexity within large, fragmented river systems.

  15. Analytical methods for predicting contaminant transport

    International Nuclear Information System (INIS)

    Pigford, T.H.

    1989-09-01

    This paper summarizes some of the previous and recent work at the University of California on analytical solutions for predicting contaminate transport in porous and fractured geologic media. Emphasis is given here to the theories for predicting near-field transport, needed to derive the time-dependent source term for predicting far-field transport and overall repository performance. New theories summarized include solubility-limited release rate with flow backfill in rock, near-field transport of radioactive decay chains, interactive transport of colloid and solute, transport of carbon-14 as carbon dioxide in unsaturated rock, and flow of gases out of and a waste container through cracks and penetrations. 28 refs., 4 figs

  16. Elucidation of the glucose transport pathway in glucose transporter 4 via steered molecular dynamics simulations.

    Directory of Open Access Journals (Sweden)

    Aswathy Sheena

    Full Text Available BACKGROUND: GLUT4 is a predominant insulin regulated glucose transporter expressed in major glucose disposal tissues such as adipocytes and muscles. Under the unstimulated state, GLUT4 resides within intracellular vesicles. Various stimuli such as insulin translocate this protein to the plasma membrane for glucose transport. In the absence of a crystal structure for GLUT4, very little is known about the mechanism of glucose transport by this protein. Earlier we proposed a homology model for GLUT4 and performed a conventional molecular dynamics study revealing the conformational rearrangements during glucose and ATP binding. However, this study could not explain the transport of glucose through the permeation tunnel. METHODOLOGY/PRINCIPAL FINDINGS: To elucidate the molecular mechanism of glucose transport and its energetic, a steered molecular dynamics study (SMD was used. Glucose was pulled from the extracellular end of GLUT4 to the cytoplasm along the pathway using constant velocity pulling method. We identified several key residues within the tunnel that interact directly with either the backbone ring or the hydroxyl groups of glucose. A rotation of glucose molecule was seen near the sugar binding site facilitating the sugar recognition process at the QLS binding site. CONCLUSIONS/SIGNIFICANCE: This study proposes a possible glucose transport pathway and aids the identification of several residues that make direct interactions with glucose during glucose transport. Mutational studies are required to further validate the observation made in this study.

  17. Opioid transport by ATP-binding cassette transporters at the blood-brain barrier: implications for neuropsychopharmacology.

    Science.gov (United States)

    Tournier, Nicolas; Declèves, Xavier; Saubaméa, Bruno; Scherrmann, Jean-Michel; Cisternino, Salvatore

    2011-01-01

    Some of the ATP-binding cassette (ABC) transporters like P-glycoprotein (P-gp; ABCB1, MDR1), BCRP (ABCG2) and MRPs (ABCCs) that are present at the blood-brain barrier (BBB) influence the brain pharmacokinetics (PK) of their substrates by restricting their uptake or enhancing their clearance from the brain into the blood, which has consequences for their CNS pharmacodynamics (PD). Opioid drugs have been invaluable tools for understanding the PK-PD relationships of these ABC-transporters. The effects of morphine, methadone and loperamide on the CNS are modulated by P-gp. This review examines the ways in which other opioid drugs and some of their active metabolites interact with ABC transporters and suggests new mechanisms that may be involved in the variability of the response of the CNS to these drugs like carrier-mediated system belonging to the solute carrier (SLC) superfamily. Exposure to opioids may also alter the expression of ABC transporters. P-gp can be overproduced during morphine treatment, suggesting that the drug has a direct or, more likely, an indirect action. Variations in cerebral neurotransmitters during exposure to opioids and the release of cytokines during pain could be new endogenous stimuli affecting transporter synthesis. This review concludes with an analysis of the pharmacotherapeutic and clinical impacts of the interactions between ABC transporters and opioids.

  18. Electrical energy conversion and transport an interactive computer-based approach

    CERN Document Server

    Karady, George G

    2013-01-01

    Provides relevant material for engineering students and practicing engineers who want to learn the basics of electrical power transmission, generation, and usage This Second Edition of Electrical Energy Conversion and Transport is thoroughly updated to address the recent environmental effects of electric power generation and transmission, which have become more important in conjunction with the deregulation of the industry. The maintenance and development of the electrical energy generation and transport industry requires well-trained engineers who are able to use mode

  19. A microdot multilayer oxide device: let us tune the strain-ionic transport interaction.

    Science.gov (United States)

    Schweiger, Sebastian; Kubicek, Markus; Messerschmitt, Felix; Murer, Christoph; Rupp, Jennifer L M

    2014-05-27

    In this paper, we present a strategy to use interfacial strain in multilayer heterostructures to tune their resistive response and ionic transport as active component in an oxide-based multilayer microdot device on chip. For this, fabrication of strained multilayer microdot devices with sideways attached electrodes is reported with the material system Gd0.1Ce0.9O(2-δ)/Er2O3. The fast ionic conducting Gd0.1Ce0.9O(2-δ) single layers are altered in lattice strain by the electrically insulating erbia phases of a microdot. The strain activated volume of the Gd0.1Ce0.9O(2-δ) is investigated by changing the number of individual layers from 1 to 60 while keeping the microdot at a constant thickness; i.e., the proportion of strained volume was systematically varied. Electrical measurements showed that the activation energy of the devices could be altered by Δ0.31 eV by changing the compressive strain of a microdot ceria-based phase by more than 1.16%. The electrical conductivity data is analyzed and interpreted with a strain volume model and defect thermodynamics. Additionally, an equivalent circuit model is presented for sideways contacted multilayer microdots. We give a proof-of-concept for microdot contacting to capture real strain-ionic transport effects and reveal that for classic top-electrode contacting the effect is nil, highlighting the need for sideways electric contacting on a nanoscopic scale. The near order ionic transport interaction is supported by Raman spectroscopy measurements. These were conducted and analyzed together with fully relaxed single thin film samples. Strain states are described relative to the strain activated volumes of Gd0.1Ce0.9O(2-δ) in the microdot multilayer. These findings reveal that strain engineering in microfabricated devices allows altering the ionic conduction over a wide range beyond classic doping strategies for single films. The reported fabrication route and concept of strained multilayer microdots is a promising path

  20. INTERACTION OF AIR TRANSPORTATION AND FUEL-SUPPLY COMPANIES

    Directory of Open Access Journals (Sweden)

    I. P. Zheleznaya

    2014-01-01

    Full Text Available The article describes the role of aviation fuel in the life of air transport. Fueling industry worldwide solves two main tasks - ensuring the safety and economy of air traffic. In Russia, there is one more task of airlines fuel supply. The article deals with fuel pricing taking into consideration today's realities.

  1. Dissipative time-dependent quantum transport theory.

    Science.gov (United States)

    Zhang, Yu; Yam, Chi Yung; Chen, GuanHua

    2013-04-28

    A dissipative time-dependent quantum transport theory is developed to treat the transient current through molecular or nanoscopic devices in presence of electron-phonon interaction. The dissipation via phonon is taken into account by introducing a self-energy for the electron-phonon coupling in addition to the self-energy caused by the electrodes. Based on this, a numerical method is proposed. For practical implementation, the lowest order expansion is employed for the weak electron-phonon coupling case and the wide-band limit approximation is adopted for device and electrodes coupling. The corresponding hierarchical equation of motion is derived, which leads to an efficient and accurate time-dependent treatment of inelastic effect on transport for the weak electron-phonon interaction. The resulting method is applied to a one-level model system and a gold wire described by tight-binding model to demonstrate its validity and the importance of electron-phonon interaction for the quantum transport. As it is based on the effective single-electron model, the method can be readily extended to time-dependent density functional theory.

  2. Membrane permeable C-terminal dopamine transporter peptides attenuate amphetamine-evoked dopamine release

    DEFF Research Database (Denmark)

    Rickhag, Karl Mattias; Owens, WA; Winkler, Marie-Therese

    2013-01-01

    The dopamine transporter (DAT) is responsible for sequestration of extracellular dopamine (DA). The psychostimulant amphetamine (AMPH) is a DAT substrate, which is actively transported into the nerve terminal, eliciting vesicular depletion and reversal of DA transport via DAT. Here, we investigate......-terminal protein-protein interactions are critical for AMPH-evoked DA efflux and suggest that it may be possible to target protein-protein interactions to modulate transporter function and interfere with psychostimulant effects....

  3. Fluctuation theorem for channel-facilitated membrane transport of interacting and noninteracting solutes.

    Science.gov (United States)

    Berezhkovskii, Alexander M; Bezrukov, Sergey M

    2008-05-15

    In this paper, we discuss the fluctuation theorem for channel-facilitated transport of solutes through a membrane separating two reservoirs. The transport is characterized by the probability, P(n)(t), that n solute particles have been transported from one reservoir to the other in time t. The fluctuation theorem establishes a relation between P(n)(t) and P-(n)(t): The ratio P(n)(t)/P-(n)(t) is independent of time and equal to exp(nbetaA), where betaA is the affinity measured in the thermal energy units. We show that the same fluctuation theorem is true for both single- and multichannel transport of noninteracting particles and particles which strongly repel each other.

  4. Charge transport in organic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ortmann, Frank

    2009-07-01

    The understanding of charge transport is one of the central goals in the research on semiconducting crystals. For organic crystals this is particularly complicated due to the strength of the electron-phonon interaction which requires the description of a seamless transition between the limiting cases of a coherent band-transport mechanism and incoherent hopping. In this thesis, charge transport phenomena in organic crystals are studied by theoretical means. A theory for charge transport in organic crystals is developed which covers the whole temperature range from low T, where it reproduces an expression from the Boltzmann equation for band transport, via elevated T, where it generalizes Holstein's small-polaron theory to finite bandwidths, up to high T, for which a temperature dependence equal to Marcus' electron-transfer theory is obtained. Thereby, coherent band transport and thermally induced hopping are treated on equal footing while simultaneously treating the electron-phonon interaction non-perturbatively. By avoiding the approximation of narrow polaron bands the theory allows for the description of large and small polarons and serves as a starting point for computational studies. The theoretical description is completed by using ab initio material parameters for the selected crystals under study. These material parameters are taken from density functional theory calculations for durene, naphthalene, and guanine crystals. Besides the analysis of the transport mechanism, special focus is put on the study of the relationship between mobility anisotropy and structure of the crystals. This study is supported by a 3D-visualization method for the transport channels in such crystals which has been derived in this thesis. (orig.)

  5. Interactions between oxygen permeation and homogeneous-phase fuel conversion on the sweep side of an ion transport membrane

    KAUST Repository

    Hong, Jongsup

    2013-02-01

    The interactions between oxygen permeation and homogeneous fuel oxidation reactions on the sweep side of an ion transport membrane (ITM) are examined using a comprehensive model, which couples the dependency of the oxygen permeation rate on the membrane surface conditions and detailed chemistry and transport in the vicinity of the membrane. We assume that the membrane surface is not catalytic to hydrocarbon or syngas oxidation. Results show that increasing the sweep gas inlet temperature and fuel concentration enhances oxygen permeation substantially. This is accomplished through promoting oxidation reactions (oxygen consumption) and the transport of the products and reaction heat towards the membrane, which lowers the oxygen concentration and increases the gas temperature near the membrane. Faster reactions at higher fuel concentration and higher inlet gas temperature support substantial fuel conversion and lead to a higher oxygen permeation flux without the contribution of surface catalytic activity. Beyond a certain maximum in the fuel concentration, extensive heat loss to the membrane (and feed side) reduces the oxidation kinetic rates and limits oxygen permeation as the reaction front reaches the membrane. The sweep gas flow rate and channel height have moderate impacts on oxygen permeation and fuel conversion due to the residence time requirements for the chemical reactions and the location of the reaction zone relative to the membrane surface. © 2012 Elsevier B.V.

  6. Molecular Imaging of Transporters with Positron Emission Tomography

    Science.gov (United States)

    Antoni, Gunnar; Sörensen, Jens; Hall, Håkan

    Positron emission tomography (PET) visualization of brain components in vivo is a rapidly growing field. Molecular imaging with PET is also increasingly used in drug development, especially for the determination of drug receptor interaction for CNS-active drugs. This gives the opportunity to relate clinical efficacy to per cent receptor occupancy of a drug on a certain targeted receptor and to relate drug pharmacokinetics in plasma to interaction with target protein. In the present review we will focus on the study of transporters, such as the monoamine transporters, the P-glycoprotein (Pgp) transporter, the vesicular monoamine transporter type 2, and the glucose transporter using PET radioligands. Neurotransmitter transporters are presynaptically located and in vivo imaging using PET can therefore be used for the determination of the density of afferent neurons. Several promising PET ligands for the noradrenaline transporter (NET) have been labeled and evaluated in vivo including in man, but a really useful PET ligand for NET still remains to be identified. The most promising tracer to date is (S,S)-[18F]FMeNER-D2. The in vivo visualization of the dopamine transporter (DAT) may give clues in the evaluation of conditions related to dopamine, such as Parkinson's disease and drug abuse. The first PET radioligands based on cocaine were not selective, but more recently several selective tracers such as [11C]PE2I have been characterized and shown to be suitable as PET radioligands. Although there are a large number of serotonin transporter inhibitors used today as SSRIs, it was not until very recently, when [11C]McN5652 was synthesized, that this transporter was studied using PET. New candidates as PET radioligands for the SERT have subsequently been developed and [11C]DASB and [11C]MADAM and their analogues are today the most promising ligands. The existing radioligands for Pgp transporters seem to be suitable tools for the study of both peripheral and central drug

  7. Generation and transport of fast electrons in the interaction of high intensity laser with matter; Generation et transport des electrons rapides dans l'interaction laser-matiere a haut flux

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, H

    2005-10-15

    The general context of this study is the Inertial Confinement for thermonuclear controlled fusion and, more precisely, the Fast Igniter (FI). In this context the knowledge of the generation and transport of fast electrons is crucial. This thesis is an experimental study of the generation and transport of fast electrons in the interaction of a high intensity laser ({>=} 10{sup 19} W/cm{sup 2}) with a solid target. The main diagnostic used here is the transition radiation. This radiation depends on the electrons which produce it and thus it gives important information on the electrons: energy, temperature, propagation geometry, etc. The spectral, temporal and spatial analysis permitted to put in evidence the acceleration of periodic electron bunches which, in this case, emit a Coherent Transition Radiation (CTR). During this thesis we have developed some theoretical models in order to explain the experimental results. We find this way two kinds of electron bunches, emitted either at the laser frequency ({omega}{sub 0}), either at the double of this frequency (2{omega}{sub 0}), involving several acceleration mechanisms: vacuum heating / resonance absorption and Lorentz force, respectively. These bunches are also observed in the PIC (particle-in-cell) simulations. The electron temperature is of about 2 MeV in our experimental conditions. The electrons are emitted starting from a point source (which is the laser focal spot) and then propagate in a ballistic way through the target. In some cases they can be re-injected in the target by the electrostatic field from the target edges. This diagnostic is only sensitive to the coherent relativistic electrons, which explains the weak total energy that they contain (about a few mJ). The CTR signal emitted by those fast electrons is largely dominating the signal emitted by the less energetic electrons, even if they contain the major part of the energy (about 1 J). (author)

  8. Estado situacional de los modelos basados en agentes y su impacto en la investigación organizacional

    OpenAIRE

    Ovalle Pinilla, Dayana

    2014-01-01

    En un mundo hiperconectado, dinámico y cargado de incertidumbre como el actual, los métodos y modelos analíticos convencionales están mostrando sus limitaciones. Las organizaciones requieren, por tanto, herramientas útiles que empleen tecnología de información y modelos de simulación computacional como mecanismos para la toma de decisiones y la resolución de problemas. Una de las más recientes, potentes y prometedoras es el modelamiento y la simulación basados en agentes (MSBA). Muchas organi...

  9. The Explicit-Cloud Parameterized-Pollutant hybrid approach for aerosol-cloud interactions in multiscale modeling framework models: tracer transport results

    International Nuclear Information System (INIS)

    Jr, William I Gustafson; Berg, Larry K; Easter, Richard C; Ghan, Steven J

    2008-01-01

    All estimates of aerosol indirect effects on the global energy balance have either completely neglected the influence of aerosol on convective clouds or treated the influence in a highly parameterized manner. Embedding cloud-resolving models (CRMs) within each grid cell of a global model provides a multiscale modeling framework for treating both the influence of aerosols on convective as well as stratiform clouds and the influence of clouds on the aerosol, but treating the interactions explicitly by simulating all aerosol processes in the CRM is computationally prohibitive. An alternate approach is to use horizontal statistics (e.g., cloud mass flux, cloud fraction, and precipitation) from the CRM simulation to drive a single-column parameterization of cloud effects on the aerosol and then use the aerosol profile to simulate aerosol effects on clouds within the CRM. Here, we present results from the first component of the Explicit-Cloud Parameterized-Pollutant parameterization to be developed, which handles vertical transport of tracers by clouds. A CRM with explicit tracer transport serves as a benchmark. We show that this parameterization, driven by the CRM's cloud mass fluxes, reproduces the CRM tracer transport significantly better than a single-column model that uses a conventional convective cloud parameterization

  10. The Explicit-Cloud Parameterized-Pollutant hybrid approach for aerosol-cloud interactions in multiscale modeling framework models: tracer transport results

    Energy Technology Data Exchange (ETDEWEB)

    Jr, William I Gustafson; Berg, Larry K; Easter, Richard C; Ghan, Steven J [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, PO Box 999, MSIN K9-30, Richland, WA (United States)], E-mail: William.Gustafson@pnl.gov

    2008-04-15

    All estimates of aerosol indirect effects on the global energy balance have either completely neglected the influence of aerosol on convective clouds or treated the influence in a highly parameterized manner. Embedding cloud-resolving models (CRMs) within each grid cell of a global model provides a multiscale modeling framework for treating both the influence of aerosols on convective as well as stratiform clouds and the influence of clouds on the aerosol, but treating the interactions explicitly by simulating all aerosol processes in the CRM is computationally prohibitive. An alternate approach is to use horizontal statistics (e.g., cloud mass flux, cloud fraction, and precipitation) from the CRM simulation to drive a single-column parameterization of cloud effects on the aerosol and then use the aerosol profile to simulate aerosol effects on clouds within the CRM. Here, we present results from the first component of the Explicit-Cloud Parameterized-Pollutant parameterization to be developed, which handles vertical transport of tracers by clouds. A CRM with explicit tracer transport serves as a benchmark. We show that this parameterization, driven by the CRM's cloud mass fluxes, reproduces the CRM tracer transport significantly better than a single-column model that uses a conventional convective cloud parameterization.

  11. On the transport, segregation, and dispersion of heavy and light particles interacting with rising thermal plumes

    Science.gov (United States)

    Lappa, Marcello

    2018-03-01

    A systematic numerical analysis is carried out on the multiplicity of patterns produced by inertial particles dispersed in a fluid and localized gravitational convection developing in the form of a rising thermal plume. In particular, specific numerical examples are presented to provide inputs for an increased understanding of the underlying flow-particle interaction mechanisms and cause-and-effect relationships. A rich spectrum of convective dynamics is obtained at the relatively high value of the considered Rayleigh number (Ra = 108), which naturally allows the investigation of several intriguing effects (including, but not limited to, particle interaction with plume jet, associated vortices, shear instabilities, and symmetry breaking phenomena). An important degree of freedom is introduced in the problem by changing the particle viscous drag through proper tuning of the related Stokes number (St). Similarly, inertia and weight of solid matter are varied parametrically by performing numerical simulations for both light and heavy particles at different values of the Froude number. This framework lets us identify the average behavior of particles by revealing the mean evolution. We connect such statistics to the behavior of the temporally evolving thermal plume, giving deeper insights into the particle transport mechanisms and associated dissipative dynamics.

  12. The application of fluid structure interaction techniques within finite element analyses of water-filled transport flasks

    International Nuclear Information System (INIS)

    Smith, C.; Stojko, S.

    2004-01-01

    Historically, Finite Element (FE) analyses of water-filled transport flasks and their payloads have been carried out assuming a dry environment, mainly due to a lack of robust Fluid Structure Interaction (FSI) modelling techniques. Also it has been accepted within the RAM transport industry that the presence of water would improve the impact withstand capability of dropped payloads within containers. In recent years the FE community has seen significant progress and improvement in FSI techniques. These methods have been utilised to investigate the effects of a wet environment on payload behaviour for the regulatory drop test within a recent transport licence renewal application. Fluid flow and pressure vary significantly during a wet impact and the effects on the contents become complex when water is incorporated into the flask analyses. Modelling a fluid environment within the entire flask is considered impractical; hence a good understanding of the FSI techniques and assumptions regarding fluid boundaries is required in order to create a representative FSI model. Therefore, a Verification and Validation (V and V) exercise was undertaken to underpin the FSI techniques eventually utilised. A number of problems of varying complexity have been identified to test the FSI capabilities of the explicit code LS-DYNA, which is used in the extant dry container impact analyses. RADIOSS explicit code has been used for comparison, to provide further confidence in LS-DYNA predictions. Various methods of modelling fluid are tested, and the relative advantages and limitations of each method and FSI coupling approaches are discussed. Results from the V and V problems examined provided sufficient confidence that FSI effects within containers can be accurately modelled

  13. Colloid Genesis/Transport and Flow Pathway Alterations Resulting From Interactions of Reactive Waste Solutions and Hanford Vadose Zone Sediments

    International Nuclear Information System (INIS)

    Wan, Jiamin; Tokunaga, Tetsu K.

    2001-01-01

    Leakage of underground tanks containing high-level nuclear waste solutions has been identified at various DOE facilities. The Hanford Site is one the main facilities of concern, with about 2,300 to 3,400 m3 of leaked waste liquids. Radionuclides and other contaminants have been found in elevated concentrations in the vadose zone and groundwater underneath single shell tank farms. We do not currently know the mechanisms responsible for the unexpected deep migration of some contaminants through the vadose zone, and such understanding is urgently needed for planning remediation. Due to the extreme chemical conditions of the tank waste solutions (very high pH, aluminum concentration, and ionic strength), interactions between the highly reactive waste solutions and sediments underneath the tanks can result in dissolution of primary minerals of the sediments and precipitation of secondary phases including colloidal particles. Contaminants can sorb onto and/or co-precipitate with the secondary phases. Therefore transport of strongly associated contaminants on mobile colloids can be substantially greater than without colloids. The overall objective of this research is to improve our understanding on the effects of interactions between the tank waste solution and sediments on deep contaminant migration under Hanford Site conditions. This objective will be achieved through the following four tasks: (1) colloid generation and transport studies, (2) studies on sediment permeability and chemical composition alterations, (3) quantifying associations of contaminants with secondary colloids, and (4) studies on the combined effects of the aforementioned processes on deep contaminant migration

  14. Interactive ion-mediated sap flow regulation in olive and laurel stems: physicochemical characteristics of water transport via the pit structure.

    Science.gov (United States)

    Ryu, Jeongeun; Ahn, Sungsook; Kim, Seung-Gon; Kim, TaeJoo; Lee, Sang Joon

    2014-01-01

    Sap water is distributed and utilized through xylem conduits, which are vascular networks of inert pipes important for plant survival. Interestingly, plants can actively regulate water transport using ion-mediated responses and adapt to environmental changes. However, ionic effects on active water transport in vascular plants remain unclear. In this report, the interactive ionic effects on sap transport were systematically investigated for the first time by visualizing the uptake process of ionic solutions of different ion compositions (K+/Ca2+) using synchrotron X-ray and neutron imaging techniques. Ionic solutions with lower K+/Ca2+ ratios induced an increased sap flow rate in stems of Olea europaea L. and Laurus nobilis L. The different ascent rates of ionic solutions depending on K+/Ca2+ ratios at a fixed total concentration increases our understanding of ion-responsiveness in plants from a physicochemical standpoint. Based on these results, effective structural changes in the pit membrane were observed using varying ionic ratios of K+/Ca2+. The formation of electrostatically induced hydrodynamic layers and the ion-responsiveness of hydrogel structures based on Hofmeister series increase our understanding of the mechanism of ion-mediated sap flow control in plants.

  15. OCWM Transportation Institutional Program Update on Collaborative Efforts with Key Stakeholders

    International Nuclear Information System (INIS)

    Saris, E.; Austin, P.; Offner, J.J.

    2004-01-01

    The Department of Energy's (DOE) Office of Civilian Radioactive Waste Management (OCRWM) created the Office of National Transportation in 2003 recognizing the need to revitalize and accelerate development of the transportation system. The Department has made a commitment to work through a collaborative planning process before developing specific policies and procedures and making transportation decisions. OCRWM has begun to build the institutional framework to support development of this transportation system. Interactions with stakeholders have been initiated. The authors describe the key stakeholders, identified issues, regional and national planning activities, and mechanisms for interaction

  16. Investigation of transport properties of colossal magnetoresistive materials

    International Nuclear Information System (INIS)

    Kaurav, Netram

    2006-01-01

    The transport properties, i.e. resistivity, heat capacity, thermal conductivity and optical conductivity have been theoretically analysed for colossal magnetoresistive materials within the framework of double exchange mechanism. Following an effective interaction potential, we deduce acoustic (optical) phonon modes, coupling strength for electron-phonon and phonon-impurities, the phonon (magnon) scattering rate and constants characterise the scattering of charge and heat carriers with various disorders in the crystal. The theoretical models have been developed to account the anomalies observed in the transport phenomenon. It is noticed that electron-electron, electron-phonon and electron-magnon interactions are essential in discussing the transport behaviour of doped magnetites. (author)

  17. One-Dimensional Transport with Equilibrium Chemistry (OTEQ) - A Reactive Transport Model for Streams and Rivers

    Science.gov (United States)

    Runkel, Robert L.

    2010-01-01

    OTEQ is a mathematical simulation model used to characterize the fate and transport of waterborne solutes in streams and rivers. The model is formed by coupling a solute transport model with a chemical equilibrium submodel. The solute transport model is based on OTIS, a model that considers the physical processes of advection, dispersion, lateral inflow, and transient storage. The equilibrium submodel is based on MINTEQ, a model that considers the speciation and complexation of aqueous species, acid-base reactions, precipitation/dissolution, and sorption. Within OTEQ, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (waterborne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach. The model's ability to simulate pH, precipitation/dissolution, and pH-dependent sorption provides a means of evaluating the complex interactions between instream chemistry and hydrologic transport at the field scale. This report details the development and application of OTEQ. Sections of the report describe model theory, input/output specifications, model applications, and installation instructions. OTEQ may be obtained over the Internet at http://water.usgs.gov/software/OTEQ.

  18. Ultrafast Thermal Transport at Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, David [Univ. of Illinois, Champaign, IL (United States); Murphy, Catherine [Univ. of Illinois, Champaign, IL (United States); Martin, Lane [Univ. of Illinois, Champaign, IL (United States)

    2014-10-21

    Our research program on Ultrafast Thermal Transport at Interfaces advanced understanding of the mesoscale science of heat conduction. At the length and time scales of atoms and atomic motions, energy is transported by interactions between single-particle and collective excitations. At macroscopic scales, entropy, temperature, and heat are the governing concepts. Key gaps in fundamental knowledge appear at the transitions between these two regimes. The transport of thermal energy at interfaces plays a pivotal role in these scientific issues. Measurements of heat transport with ultrafast time resolution are needed because picoseconds are the fundamental scales where the lack of equilibrium between various thermal excitations becomes a important factor in the transport physics. A critical aspect of our work has been the development of experimental methods and model systems that enabled more precise and sensitive investigations of nanoscale thermal transport.

  19. OpenDMAP: An open source, ontology-driven concept analysis engine, with applications to capturing knowledge regarding protein transport, protein interactions and cell-type-specific gene expression

    Directory of Open Access Journals (Sweden)

    Johnson Helen L

    2008-01-01

    Full Text Available Abstract Background Information extraction (IE efforts are widely acknowledged to be important in harnessing the rapid advance of biomedical knowledge, particularly in areas where important factual information is published in a diverse literature. Here we report on the design, implementation and several evaluations of OpenDMAP, an ontology-driven, integrated concept analysis system. It significantly advances the state of the art in information extraction by leveraging knowledge in ontological resources, integrating diverse text processing applications, and using an expanded pattern language that allows the mixing of syntactic and semantic elements and variable ordering. Results OpenDMAP information extraction systems were produced for extracting protein transport assertions (transport, protein-protein interaction assertions (interaction and assertions that a gene is expressed in a cell type (expression. Evaluations were performed on each system, resulting in F-scores ranging from .26 – .72 (precision .39 – .85, recall .16 – .85. Additionally, each of these systems was run over all abstracts in MEDLINE, producing a total of 72,460 transport instances, 265,795 interaction instances and 176,153 expression instances. Conclusion OpenDMAP advances the performance standards for extracting protein-protein interaction predications from the full texts of biomedical research articles. Furthermore, this level of performance appears to generalize to other information extraction tasks, including extracting information about predicates of more than two arguments. The output of the information extraction system is always constructed from elements of an ontology, ensuring that the knowledge representation is grounded with respect to a carefully constructed model of reality. The results of these efforts can be used to increase the efficiency of manual curation efforts and to provide additional features in systems that integrate multiple sources for

  20. Stochastic models of intracellular transport

    KAUST Repository

    Bressloff, Paul C.

    2013-01-09

    The interior of a living cell is a crowded, heterogenuous, fluctuating environment. Hence, a major challenge in modeling intracellular transport is to analyze stochastic processes within complex environments. Broadly speaking, there are two basic mechanisms for intracellular transport: passive diffusion and motor-driven active transport. Diffusive transport can be formulated in terms of the motion of an overdamped Brownian particle. On the other hand, active transport requires chemical energy, usually in the form of adenosine triphosphate hydrolysis, and can be direction specific, allowing biomolecules to be transported long distances; this is particularly important in neurons due to their complex geometry. In this review a wide range of analytical methods and models of intracellular transport is presented. In the case of diffusive transport, narrow escape problems, diffusion to a small target, confined and single-file diffusion, homogenization theory, and fractional diffusion are considered. In the case of active transport, Brownian ratchets, random walk models, exclusion processes, random intermittent search processes, quasi-steady-state reduction methods, and mean-field approximations are considered. Applications include receptor trafficking, axonal transport, membrane diffusion, nuclear transport, protein-DNA interactions, virus trafficking, and the self-organization of subcellular structures. © 2013 American Physical Society.

  1. The DOE transportation strategy: Public information, communications network and issue resolution

    International Nuclear Information System (INIS)

    Philpott, R.E.

    1986-01-01

    The OCRWM plans to issue a draft ''comprehensive transportation plan'' in the fall of 1987 that combines the Institutional Plan, the Transportation Business Plan (DOE/RW-0046, January 1986), and a framework for transportation operational procedures. This paper reviews the major elements of the OCRWM's institutional strategy. The OCRWM's strategy for addressing transportation issues relies on the development of public information to foster public understanding and acceptance of program activities and goals, and active communication and interaction with all parties having an interest in the development and operation of the NWPA transportation program. The OCRWM's goal in conducting such activities is to foster cooperative effort in addressing transportation issues, and to focus on communication and constructive interaction rather than conflict

  2. Dossier: transport of radioactive materials

    International Nuclear Information System (INIS)

    Mignon, H.; Brachet, Y.; Turquet de Beauregard, G.; Mauny, G.; Robine, F.; Plantet, F.; Pestel Lefevre, O.; Hennenhofer, G.; Bonnemains, J.

    1997-01-01

    This dossier is entirely devoted to the transportation of radioactive and fissile materials of civil use. It comprises 9 papers dealing with: the organization of the control of the radioactive materials transport safety (safety and security aspects, safety regulations, safety analysis and inspection, emergency plans, public information), the technical aspects of the regulation concerning the transport of radioactive materials (elaboration of regulations and IAEA recommendations, risk assessments, defense in depth philosophy and containers, future IAEA recommendations, expertise-research interaction), the qualification of containers (regulations, test facilities), the Transnucleaire company (presentation, activity, containers for spent fuels), the packages of radioactive sources for medical use (flux, qualification, safety and transport), an example of accident during radioactive materials transportation: the Apach train derailment (February 4, 1997), the sea transport of radioactive materials (international maritime organization (OMI), international maritime dangerous goods (IMDG) code, irradiated nuclear fuel (INF) safety rules), the transport of radioactive materials in Germany, and the point of view from an external observer. (J.S.)

  3. Role of molecular charge in nucleocytoplasmic transport.

    Directory of Open Access Journals (Sweden)

    Alexander Goryaynov

    Full Text Available Transport of genetic materials and proteins between the nucleus and cytoplasm of eukaryotic cells is mediated by nuclear pore complexes (NPCs. A selective barrier formed by phenylalanine-glycine (FG nucleoporins (Nups with net positive charges in the NPC allows for passive diffusion of signal-independent small molecules and transport-receptor facilitated translocation of signal-dependent cargo molecules. Recently, negative surface charge was postulated to be another essential criterion for selective passage through the NPC. However, the charge-driven mechanism in determining the transport kinetics and spatial transport route for either passive diffusion or facilitated translocation remains obscure. Here we employed high-speed single-molecule fluorescence microscopy with an unprecedented spatiotemporal resolution of 9 nm and 400 µs to uncover these mechanistic fundamentals for nuclear transport of charged substrates through native NPCs. We found that electrostatic interaction between negative surface charges on transiting molecules and the positively charged FG Nups, although enhancing their probability of binding to the NPC, never plays a dominant role in determining their nuclear transport mode or spatial transport route. A 3D reconstruction of transport routes revealed that small signal-dependent endogenous cargo protein constructs with high positive surface charges that are destined to the nucleus, rather than repelled from the NPC as suggested in previous models, passively diffused through an axial central channel of the NPC in the absence of transport receptors. Finally, we postulated a comprehensive map of interactions between transiting molecules and FG Nups during nucleocytoplasmic transport by combining the effects of molecular size, signal and surface charge.

  4. Comparative proteomic analysis reveals a dynamic pollen plasma membrane protein map and the membrane landscape of receptor-like kinases and transporters important for pollen tube growth and interaction with pistils in rice.

    Science.gov (United States)

    Yang, Ning; Wang, Tai

    2017-01-05

    The coordination of pollen tube (PT) growth, guidance and timely growth arrest and rupture mediated by PT-pistil interaction is crucial for the PT to transport sperm cells into ovules for double fertilization. The plasma membrane (PM) represents an important interface for cell-cell interaction, and PM proteins of PTs are pioneers for mediating PT integrity and interaction with pistils. Thus, understanding the mechanisms underlying these events is important for proteomics. Using the efficient aqueous polymer two-phase system and alkali buffer treatment, we prepared high-purity PM from mature and germinated pollen of rice. We used iTRAQ quantitative proteomic methods and identified 1,121 PM-related proteins (PMrPs) (matched to 899 loci); 192 showed differential expression in the two pollen cell types, 119 increased and 73 decreased in abundance during germination. The PMrP and differentially expressed PMrP sets all showed a functional skew toward signal transduction, transporters, wall remodeling/metabolism and membrane trafficking. Their genomic loci had strong chromosome bias. We found 37 receptor-like kinases (RLKs) from 8 kinase subfamilies and 209 transporters involved in flux of diversified ions and metabolites. In combination with the rice pollen transcriptome data, we revealed that in general, the protein expression of these PMrPs disagreed with their mRNA expression, with inconsistent mRNA expression for 74% of differentially expressed PMrPs. This study identified genome-wide pollen PMrPs, and provided insights into the membrane profile of receptor-like kinases and transporters important for pollen tube growth and interaction with pistils. These pollen PMrPs and their mRNAs showed discordant expression. This work provides resource and knowledge to further dissect mechanisms by which pollen or the PT controls PMrP abundance and monitors interactions and ion and metabolite exchanges with female cells in rice.

  5. Membrane-traversing mechanism of thyroid hormone transport by monocarboxylate transporter 8.

    Science.gov (United States)

    Protze, Jonas; Braun, Doreen; Hinz, Katrin Manuela; Bayer-Kusch, Dorothea; Schweizer, Ulrich; Krause, Gerd

    2017-06-01

    Monocarboxylate transporter 8 (MCT8) mediates thyroid hormone (TH) transport across the plasma membrane in many cell types. In order to better understand its mechanism, we have generated three new MCT8 homology models based on sugar transporters XylE in the intracellular opened (PDB ID: 4aj4) and the extracellular partly occluded (PDB ID: 4gby) conformations as well as FucP (PDB ID: 3o7q) and GLUT3 (PDB ID: 4zwc) in the fully extracellular opened conformation. T 3 -docking studies from both sides revealed interactions with His192, His415, Arg445 and Asp498 as previously identified. Selected mutations revealed further transport-sensitive positions mainly at the discontinuous transmembrane helices TMH7 and 10. Lys418 is potentially involved in neutralising the charge of the TH substrate because it can be replaced by charged, but not by uncharged, amino acids. The side chain of Thr503 was hypothesised to stabilise a helix break at TMH10 that undergoes a prominent local shift during the transport cycle. A T503V mutation accordingly affected transport. The aromatic Tyr419, the polar Ser313 and Ser314 as well as the charged Glu422 and Glu423 lining the transport channel have been studied. Based on related sugar transporters, we suggest an alternating access mechanism for MCT8 involving a series of amino acid positions previously and newly identified as critical for transport.

  6. The Particle Beam Optics Interactive Computer Laboratory

    International Nuclear Information System (INIS)

    Gillespie, George H.; Hill, Barrey W.; Brown, Nathan A.; Babcock, R. Chris; Martono, Hendy; Carey, David C.

    1997-01-01

    The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) is an educational software concept to aid students and professionals in learning about charged particle beams and particle beam optical systems. The PBO Lab is being developed as a cross-platform application and includes four key elements. The first is a graphic user interface shell that provides for a highly interactive learning session. The second is a knowledge database containing information on electric and magnetic optics transport elements. The knowledge database provides interactive tutorials on the fundamental physics of charged particle optics and on the technology used in particle optics hardware. The third element is a graphical construction kit that provides tools for students to interactively and visually construct optical beamlines. The final element is a set of charged particle optics computational engines that compute trajectories, transport beam envelopes, fit parameters to optical constraints and carry out similar calculations for the student designed beamlines. The primary computational engine is provided by the third-order TRANSPORT code. Augmenting TRANSPORT is the multiple ray tracing program TURTLE and a first-order matrix program that includes a space charge model and support for calculating single particle trajectories in the presence of the beam space charge. This paper describes progress on the development of the PBO Lab

  7. Quantum Transport Through Tunable Molecular Diodes

    KAUST Repository

    Obodo, Tobechukwu Joshua

    2017-07-31

    Employing self-interaction corrected density functional theory combined with the non-equilibrium Green\\'s function method, we study the quantum transport through molecules with different numbers of phenyl (donor) and pyrimidinyl (acceptor) rings in order to evaluate the effects of the molecular composition on the transport properties. Excellent agreement with the results of recent experiments addressing the rectification behavior of molecular junctions is obtained, which demonstrates the potential of quantum transport simulations for designing high performance junctions by tuning the molecular specifications.

  8. Strong enhancement of transport by interaction on contact links

    DEFF Research Database (Denmark)

    Bohr, Dan; Schmitteckert, P.

    2007-01-01

    Strong repulsive interactions within a one-dimensional Fermi system in a two-probe configuration normally lead to a reduced off-resonance conductance. We show that if the repulsive interaction extends to the contact regions, a strong increase of the conductance may occur, even for systems where o...

  9. Air transport system

    CERN Document Server

    Schmitt, Dieter

    2016-01-01

    The book addresses all major aspects to be considered for the design and operation of aircrafts within the entire transportation chain. It provides the basic information about the legal environment, which defines the basic requirements for aircraft design and aircraft operation. The interactions between  airport, air traffic management and the airlines are described. The market forecast methods and the aircraft development process are explained to understand the very complex and risky business of an aircraft manufacturer. The principles of flight physics as basis for aircraft design are presented and linked to the operational and legal aspects of air transport including all environmental impacts. The book is written for graduate students as well as for engineers and experts, who are working in aerospace industry, at airports or in the domain of transport and logistics.

  10. Characterization of calculation of in-situ retardation factors of contaminant transport using naturally-radionuclides and rock/water interaction occurring U-Series disequilibria timescales. 1997 annual progress report

    International Nuclear Information System (INIS)

    Goldstein, S.; Ku, T.L.; Luo, S.; Murrel, M.; Roback, R.

    1997-01-01

    'The research is directed toward a quantitative assessment of contaminant transport rates in fracture-rock systems using uranium-series radionuclides. Naturally occurring uranium-and thorium-series radioactive disequilibria will provide information on the rates of adsorption-desorption and transport of radioactive contaminants as well as on fluid transport and rock dissolution in a natural setting. This study will also provide an improved characterization of preferential flow and contaminant transport at the Idaho Environmental and Engineering Lab. (INEEL) site. To a lesser extent, the study will include rocks in the unsaturated zone. The authors will produce a realistic model of radionuclide migration under unsaturated and saturated field conditions at the INEEL site, taking into account the retardation processes involved in the rock/water interaction. The major tasks are to (1) determine the natural distribution of U, Th, Pa and Ra isotopes in rock minerals. sorbed phases on the rocks, and in fluids from both saturated and unsaturated zones at the site, and (2) study rock/water interaction processes using U/Th series disequilibrium and a statistical analysis-based model for the Geologic heterogeneity plays an important role in transporting contaminants in fractured rocks. Preferential flow paths in the fractured rocks act as a major pathway for transport of radioactive contaminants in groundwaters. The weathering/dissolution of rock by groundwater also influences contaminant mobility. Thus, it is important to understand the hydrogeologic features of the site and their impact on the migration of radioactive contaminants. In this regard, quantification of the rock weathering/dissolution rate and fluid residence time from the observed decay-series disequilibria will be valuable. By mapping the spatial distribution of the residence time of groundwater in fractured rocks, the subsurface preferential flow paths (with high rock permeability and short fluid residence

  11. Interaction of bootstrap-current-driven magnetic islands

    International Nuclear Information System (INIS)

    Hegna, C.C.; Callen, J.D.

    1991-10-01

    The formation and interaction of fluctuating neoclassical pressure gradient driven magnetic islands is examined. The interaction of magnetic islands produces a stochastic region around the separatrices of the islands. This interaction causes the island pressure profile to be broadened, reducing the island bootstrap current and drive for the magnetic island. A model is presented that describes the magnetic topology as a bath of interacting magnetic islands with low to medium poloidal mode number (m congruent 3-30). The islands grow by the bootstrap current effect and damp due to the flattening of the pressure profile near the island separatrix caused by the interaction of the magnetic islands. The effect of this sporadic growth and decay of the islands (''magnetic bubbling'') is not normally addressed in theories of plasma transport due to magnetic fluctuations. The nature of the transport differs from statistical approaches to magnetic turbulence since the radial step size of the plasma transport is now given by the characteristic island width. This model suggests that tokamak experiments have relatively short-lived, coherent, long wavelength magnetic oscillations present in the steep pressure-gradient regions of the plasma. 42 refs

  12. Channel-accelerating gap interaction and beam acceleration and transport experiments with the recirculating linear accelerator (RLA)

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Smith, D.L.; Poukey, J.W.; Wagner, J.S.; Bennett, L.F.; Olson, W.R.; Turman, B.N.; Prestwich, K.R.; Wells, J.; Struve, K.

    1992-01-01

    The lifetime of the Ion Focusing Regime (IFR) channel following the pulsing of the post-accelerating gaps is critical for open-ended low energy devices. It dictates the number of allowable beam recirculations through the gaps. In the case of a closed racetrack configuration, it is significant but not as critical, since the presence of the electron beam focuses the ions and lengthens the lifetime of the ion channel. The authors have experimentally established that pulsing an accelerating gap perturbs the IFR channel. However for the parameters studied, the lifetime is long enough to allow at least four beam recirculations in a spiral device. In addition transparent grids of cusp fields positioned upstream and downstream from the gaps prevent them from perturbing the IFR channel. Experiments were performed with and without injected electron beams. For the experiments investigating the IFR channel interaction with the accelerating gap, the injector was removed and the beam line was extended downstream and upstream from the accelerating cavity. Only the first straight section of the RLA with one accelerating cavity (ET-2) was utilized. The acceleration and transport experiments were performed utilizing two injectors: first the low energy 1.3-MV Isolated Blumlein (IB) injector and most recently the new 4-MV 20-kA injector. Beams of 6--20 kA current were produced and successfully transported and accelerated through the ET-2 post-accelerating gap. For both injectors an apertured non-immersed ion-focused foilless diode was selected among various options. It is the simplest and easiest to operate and can be adjusted to provide variable beam impedance loads to the injector. The transport efficiencies were 90% for the low energy injector and 100% for the new 4-MV injector. The beam Gaussian profile and radius (5 mm) remain the same through acceleration. Experimental results will be presented and compared with numerical simulations

  13. Organic anion transporter 3- and organic anion transporting polypeptides 1B1- and 1B3-mediated transport of catalposide

    Directory of Open Access Journals (Sweden)

    Jeong HU

    2015-01-01

    M, respectively. However, catalposide did not significantly inhibit the transport activities of OCT1, OCT2, OAT1, P-gp, or BCRP. In conclusion, OAT3, OATP1B1, and OATP1B3 are major transporters that may regulate the pharmacokinetic properties and may cause herb–drug interactions of catalposide, although their clinical relevance awaits further evaluation. Keywords: catalposide, drug transporters, herb–drug interaction, OAT3, OATP1B1, OATP1B3

  14. The serotonin transporter: Examination of the changes in transporter affinity induced by ligand binding

    International Nuclear Information System (INIS)

    Humphreys, C.J.

    1989-01-01

    The plasmalemmal serotonin transporter uses transmembrane gradients of Na + , Cl - and K + to accumulate serotonin within blood platelets. Transport is competitively inhibited by the antidepressant imipramine. Like serotonin transport, imipramine binding requires Na + . Unlike serotonin, however, imipramine does not appear to be transported. To gain insight into the mechanism of serotonin transport the author have analyzed the influences of Na + and Cl - , the two ions cotransported with serotonin, on both serotonin transport and the interaction of imipramine and other antidepressant drugs with the plasmalemmal serotonin transporter of human platelets. Additionally, the author have synthesized, purified and characterized the binding of 2-iodoimipramine to the serotonin transporter. Finally, the author have conducted a preliminary study of the inhibition of serotonin transport and imipramine binding produced by dicyclohexylcarbodiimide. My results reveal many instances of positive heterotropic cooperativity in ligand binding to the serotonin transporter. Na + binding enhances the transporters affinity for imipramine and several other antidepressant drugs, and also increases the affinity for Cl - . Cl - enhances the transporters affinity for imipramine, as well as for Na + . At concentrations in the range of its K M for transport serotonin is a competitive inhibitor of imipramine binding. At much higher concentrations, however, serotonin also inhibits imipramines dissociation rate constant. This latter effect which is Na + -independent and species specific, is apparently produced by serotonin binding at a second, low affinity site on, or near, the transporter complex. Iodoimipramine competitively inhibit both [ 3 H]imipramine binding and [ 3 H]serotonin transport

  15. Colloid-Facilitated Transport of Radionuclides Through The Vadose Zone

    International Nuclear Information System (INIS)

    Markus Flury; James B. Harsh; John F. McCarthy' Peter C. Lichtner; John M. Zachara

    2007-01-01

    The main purpose of this project was to advance the basic scientific understanding of colloid and colloid-facilitated Cs transport of radionuclides in the vadose zone. We focused our research on the hydrological and geochemical conditions beneath the leaking waste tanks at the USDOE Hanford reservation. Specific objectives were (1) to determine the lability and thermodynamic stability of colloidal materials, which form after reacting Hanford sediments with simulated Hanford Tank Waste, (2) to characterize the interactions between colloidal particles and contaminants, i.e., Cs and Eu, (3) to determine the potential of Hanford sediments for in situ mobilization of colloids, (4) to evaluate colloid-facilitated radionuclide transport through sediments under unsaturated flow, (5) to implement colloid-facilitated contaminant transport mechanisms into a transport model, and (6) to improve conceptual characterization of colloid-contaminant-soil interactions and colloid-facilitated transport for clean-up procedures and long-term risk assessment

  16. 'Complexity' and anomalous transport in space plasmas

    International Nuclear Information System (INIS)

    Chang, Tom; Wu Chengchin

    2002-01-01

    'Complexity' has become a hot topic in nearly every field of modern physics. Space plasma is of no exception. In this paper, it is demonstrated that the sporadic and localized interactions of magnetic coherent structures are the origin of 'complexity' in space plasmas. The intermittent localized interactions, which generate the anomalous diffusion, transport, and evolution of the macroscopic state variables of the overall dynamical system, may be modeled by a triggered (fast) localized chaotic growth equation of a set of relevant order parameters. Such processes would generally pave the way for the global system to evolve into a 'complex' state of long-ranged interactions of fluctuations, displaying the phenomenon of forced and/or self-organized criticality. An example of such type of anomalous transport and evolution in a sheared magnetic field is provided via two-dimensional magnetohydrodynamic simulations. The coarse-grained dissipation due to the intermittent triggered interactions among the magnetic coherent structures induces a 'fluctuation-induced nonlinear instability' that reconfigures the sheared magnetic field into an X-point magnetic geometry (in the mean field sense), leading to the anomalous acceleration of the magnetic coherent structures. A phenomenon akin to such type of anomalous transport and acceleration, the so-called bursty bulk flows, has been commonly observed in the plasma sheet of the Earth's magnetotail

  17. Arg188 in rice sucrose transporter OsSUT1 is crucial for substrate transport

    Directory of Open Access Journals (Sweden)

    Sun Ye

    2012-11-01

    Full Text Available Abstract Background Plant sucrose uptake transporters (SUTs are H+/sucrose symporters related to the major facilitator superfamily (MFS. SUTs are essential for plant growth but little is known about their transport mechanism. Recent work identified several conserved, charged amino acids within transmembrane spans (TMS in SUTs that are essential for transport activity. Here we further evaluated the role of one of these positions, R188 in the fourth TMS of OsSUT1, a type II SUT. Results The OsSUT1(R188K mutant, studied by expression in plants, yeast, and Xenopus oocytes, did not transport sucrose but showed a H+ leak that was blocked by sucrose. The H+ leak was also blocked by β-phenyl glucoside which is not translocated by OsSUT1. Replacing the corresponding Arg in type I and type III SUTs, AtSUC1(R163K and LjSUT4(R169K, respectively, also resulted in loss of sucrose transport activity. Fluorination at the glucosyl 3 and 4 positions of α-phenyl glucoside greatly decreased transport by wild type OsSUT1 but did not affect the ability to block H+ leak in the R188K mutant. Conclusion OsSUT1 R188 appears to be essential for sucrose translocation but not for substrate interaction that blocks H+ leak. Therefore, we propose that an additional binding site functions in the initial recognition of substrates. The corresponding Arg in type I and III SUTs are equally important. We propose that R188 interacts with glucosyl 3-OH and 4-OH during translocation.

  18. Live Cell Discovery of Microbial Vitamin Transport and Enzyme-Cofactor Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Lindsey N.; Koech, Phillip K.; Plymale, Andrew E.; Landorf, Elizabeth V.; Konopka, Allan; Collart, Frank; Lipton, Mary S.; Romine, Margaret F.; Wright, Aaron T.

    2016-02-02

    The rapid completion of microbial genomes is inducing a conundrum in functional gene discovery. Novel methods are critically needed to shorten the gap between characterizing a microbial genome and experimentally validating bioinformatically-predicted functions. Of particular importance are transport mechanisms, used to shuttle nutrients and metabolites across cell mem-branes, such as B vitamins, which are indispensable to metabolic reactions crucial to the survival of diverse microbes ranging from members of environmental microbial communities to human pathogens. Methods to accurately assign function and specificity for a wide range of experimentally unidentified and/or predicted membrane-embedded transport proteins, and characterization of intra-cellular enzyme-cofactor/nutrient associations are needed to enable a significantly improved understanding of microbial biochemis-try and physiology, how microbes associate with others, and how they sense and respond to environmental perturbations. Chemical probes derived from B vitamins B1, B2, and B7 have allowed us to experimentally address the aforementioned needs by identifying B vitamin transporters and intracellular protein-cofactor associations through live cell labeling of the filamentous anoxygenic pho-toheterotroph, Chloroflexus aurantiacus J-10-fl, known for both B vitamin biosynthesis and environmental salvage. Our probes provide a unique opportunity to directly link cellular activity and protein function back to ecosystem and/or host dynamics by iden-tifying B vitamin transport and disposition mechanisms required for survival.

  19. Diffusion transport of nanoparticles at nanochannel boundaries

    International Nuclear Information System (INIS)

    Mahadevan, T. S.; Milosevic, M.; Kojic, M.; Hussain, F.; Kojic, N.; Serda, R.; Ferrari, M.; Ziemys, A.

    2013-01-01

    The manipulation of matter at the nanoscale has unleashed a great potential for engineering biomedical drug carriers, but the transport of nanoparticles (NPs) under nanoscale confinement is still poorly understood. Using colloidal physics to describe NP interactions, we have computationally studied the passive transport of NPs using experimentally relevant conditions from bulk into a nanochannel of 60–90 nm height. NP size, channel height, and the Debye length are comparable so that changes in nanoscale dimensions may induce substantial changes in NP transport kinetics. We show that subtle changes in nanochannel dimensions may alter the energy barrier by about six orders of magnitude resulting in different NP penetration depths and diffusion mechanisms: ballistic, first-order and quasi zero-order transport regimes. The analysis of NP diffusion by continuum methods reveals that apparent diffusivity is reduced by decreasing channel size. The continuum finite element (FE) numerical method reproduced the colloidal model results only when surface interactions were accounted for. These results give a new insight into NP passive transport at the boundaries of nanoconfined domains, and have implications on the design of nanoscale fluidics and NP systems for biomedical and engineering applications.

  20. Coupled electric and transport phenomena in porous media

    NARCIS (Netherlands)

    Li, Shuai

    2014-01-01

    The coupled electrical and transport properties of clay-containing porous media are the topics of interest in this study. Both experimental and numerical (pore network modeling) techniques are employed to gain insight into the macro-scale interaction between electrical and solute transport phenomena

  1. Computational Nanophotonics: modeling optical interactions and transport in tailored nanosystem architectures

    Energy Technology Data Exchange (ETDEWEB)

    Schatz, George [Northwestern Univ., Evanston, IL (United States); Ratner, Mark [Northwestern Univ., Evanston, IL (United States)

    2014-02-27

    This report describes research by George Schatz and Mark Ratner that was done over the period 10/03-5/09 at Northwestern University. This research project was part of a larger research project with the same title led by Stephen Gray at Argonne. A significant amount of our work involved collaborations with Gray, and there were many joint publications as summarized later. In addition, a lot of this work involved collaborations with experimental groups at Northwestern, Argonne, and elsewhere. The research was primarily concerned with developing theory and computational methods that can be used to describe the interaction of light with noble metal nanoparticles (especially silver) that are capable of plasmon excitation. Classical electrodynamics provides a powerful approach for performing these studies, so much of this research project involved the development of methods for solving Maxwell’s equations, including both linear and nonlinear effects, and examining a wide range of nanostructures, including particles, particle arrays, metal films, films with holes, and combinations of metal nanostructures with polymers and other dielectrics. In addition, our work broke new ground in the development of quantum mechanical methods to describe plasmonic effects based on the use of time dependent density functional theory, and we developed new theory concerned with the coupling of plasmons to electrical transport in molecular wire structures. Applications of our technology were aimed at the development of plasmonic devices as components of optoelectronic circuits, plasmons for spectroscopy applications, and plasmons for energy-related applications.

  2. The inhibitory effects of five alkaloids on the substrate transport mediated through human organic anion and cation transporters.

    Science.gov (United States)

    Shams, Tahiatul; Lu, Xiaoxi; Zhu, Ling; Zhou, Fanfan

    2018-02-01

    1. Human solute carrier transporters (SLCs) are important membrane proteins mediate the cellular transport of many endogenous and exogenous substances. Organic anion/cation transporters (OATs/OCTs) and organic anion transporting polypeptides (OATPs) are essential SLCs involved in drug influx. Drug-drug/herb interactions through competing for specific SLCs often lead to unsatisfied therapeutic outcomes and/or unwanted side effects. In this study, we comprehensively investigated the inhibitory effects of five clinically relevant alkaloids (dendrobine, matrine, oxymatrine, tryptanthrin and chelerythrine) on the substrate transport through several OATs/OCTs and OATPs. 2. We performed transport functional assay and kinetic analysis on the HEK-293 cells over-expressing each SLC gene. 3. Our data showed tryptanthrin significantly inhibited the transport activity of OAT3 (IC 50  = 0.93 ± 0.22 μM, K i  = 0.43 μM); chelerythrine acted as a potent inhibitor to the substrate transport mediated through OATP1A2 (IC 50  = 0.63 ± 0.43 μM, K i  = 0.60 μM), OCT1 (IC 50  = 13.60 ± 2.81 μM) and OCT2 (IC 50  =10.80 ± 1.16 μM). 4. Our study suggested tryptanthrin and chelerythrine could potently impact on the drug transport via specific OATs/OCTs. Therefore, the co-administration of these alkaloids with drugs could have clinical consequences due to drug-drug/herb interactions. Precautions should be warranted in the multi-drug therapies involving these alkaloids.

  3. Understanding spatial and temporal patterning of astrocyte calcium transients via interactions between network transport and extracellular diffusion

    Science.gov (United States)

    Shtrahman, E.; Maruyama, D.; Olariu, E.; Fink, C. G.; Zochowski, M.

    2017-02-01

    Astrocytes form interconnected networks in the brain and communicate via calcium signaling. We investigate how modes of coupling between astrocytes influence the spatio-temporal patterns of calcium signaling within astrocyte networks and specifically how these network interactions promote coordination within this group of cells. To investigate these complex phenomena, we study reduced cultured networks of astrocytes and neurons. We image the spatial temporal patterns of astrocyte calcium activity and quantify how perturbing the coupling between astrocytes influences astrocyte activity patterns. To gain insight into the pattern formation observed in these cultured networks, we compare the experimentally observed calcium activity patterns to the patterns produced by a reduced computational model, where we represent astrocytes as simple units that integrate input through two mechanisms: gap junction coupling (network transport) and chemical release (extracellular diffusion). We examine the activity patterns in the simulated astrocyte network and their dependence upon these two coupling mechanisms. We find that gap junctions and extracellular chemical release interact in astrocyte networks to modulate the spatiotemporal patterns of their calcium dynamics. We show agreement between the computational and experimental findings, which suggests that the complex global patterns can be understood as a result of simple local coupling mechanisms.

  4. Dynamic transport study of the plasmas with transport improvement in LHD and JT-60U

    International Nuclear Information System (INIS)

    Ida, K.; Inagaki, S.; Sakamoto, R.; Tanaka, K.; Fujita, T.; Funaba, H.; Kubo, S.; Yoshinuma, M.; Shimozuma, T.; Takeiri, Y.; Ikeda, K.; Michael, C.; Tokuzawa, T.; Sakamoto, Y.; Takenaga, H.; Isayama, A.; Matsunaga, G.; Ide, S.

    2009-01-01

    Transport analysis during the transient phase of heating (a dynamic transport study) applied to the plasma with internal transport barriers (ITBs) in the Large Helical Device (LHD) heliotron and the JT-60U tokamak is described. In the dynamic transport study the time of transition from the L-mode plasma to the ITB plasma is clearly determined by the onset of flattening of the temperature profile in the core region and a spontaneous phase transition from a zero curvature ITB (hyperbolic tangent shaped ITB) or a positive curvature ITB (concaved shaped ITB) to a negative curvature ITB (convex shaped ITB) and its back-transition are observed. The flattening of the core region of the ITB transition and the back-transition between a zero curvature ITB and a convex ITB suggest the strong interaction of turbulent transport in space.

  5. Harpin Hpa1 Interacts with Aquaporin PIP1;4 to Promote the Substrate Transport and Photosynthesis in Arabidopsis.

    Science.gov (United States)

    Li, Liang; Wang, Hao; Gago, Jorge; Cui, Haiying; Qian, Zhengjiang; Kodama, Naomi; Ji, Hongtao; Tian, Shan; Shen, Dan; Chen, Yanjuan; Sun, Fengli; Xia, Zhonglan; Ye, Qing; Sun, Wei; Flexas, Jaume; Dong, Hansong

    2015-11-26

    Harpin proteins produced by plant-pathogenic Gram-negative bacteria are the venerable player in regulating bacterial virulence and inducing plant growth and defenses. A major gap in these effects is plant sensing linked to cellular responses, and plant sensor for harpin Hpa1 from rice bacterial blight pathogen points to plasma membrane intrinsic protein (PIP). Here we show that Arabidopsis AtPIP1;4 is a plasma membrane sensor of Hpa1 and plays a dual role in plasma membrane permeability of CO2 and H2O. In particular, AtPIP1;4 mediates CO2 transport with a substantial contribute to photosynthesis and further increases this function upon interacting with Hpa1 at the plasma membrane. As a result, leaf photosynthesis rates are increased and the plant growth is enhanced in contrast to the normal process without Hpa1-AtPIP1;4 interaction. Our findings demonstrate the first case that plant sensing of a bacterial harpin protein is connected with photosynthetic physiology to regulate plant growth.

  6. Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Pepper, Michael; Kumar, Sanjeev [Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom)

    2015-11-15

    For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

  7. Elevated level of human RPA interacting protein α (hRIPα) in cervical tumor cells is involved in cell proliferation through regulating RPA transport.

    Science.gov (United States)

    Namkoong, Sim; Lee, Eun-Ju; Jang, Ik-Soon; Park, Junsoo

    2012-10-19

    Replication protein A (RPA) is a eukaryotic single-stranded DNA binding protein that is essential for DNA replication, repair, and recombination, and human RPA interacting protein α (hRIPα) is the nuclear transporter of RPA. Here, we report the regulatory role of hRIPα protein in cell proliferation. Western blot analysis revealed that the level of hRIPα was frequently elevated in cervical tumors tissues and hRIPα knockdown by siRNA inhibited cellular proliferation through deregulation of the cell cycle. In addition, overexpression of hRIPα resulted in increased clonogenicity. These results indicate that hRIPα is involved in cell proliferation through regulation of RPA transport. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  8. Bronchial Mucus as a Complex Fluid: Molecular Interactions and Influence of Nanostructured Particles on Rheological and Transport Properties

    Directory of Open Access Journals (Sweden)

    Odziomek Marcin

    2017-06-01

    Full Text Available Transport properties of bronchial mucus are investigated by two-stage experimental approach focused on: (a rheological properties and (b mass transfer rate through the stagnant layer of solutions of mucus components (mucine, DNA, proteins and simulated multi-component mucus. Studies were done using thermostated horizontal diffusion cells with sodium cromoglycate and carminic acid as transferred solutes. Rheological properties of tested liquids was studied by a rotational viscometer and a cone-plate rheometer (dynamic method. First part of the studies demonstrated that inter-molecular interactions in these complex liquids influence both rheological and permeability characteristics. Transfer rate is governed not only by mucus composition and concentration but also by hydrophobic/hydrophilic properties of transported molecules. Second part was focused on the properties of such a layer in presence of selected nanostructured particles (different nanoclays and graphene oxide which may be present in lungs after inhalation. It was shown that most of such particles increase visco-elasticity of the mucus and reduce the rate of mass transfer of model drugs. Measured effects may have adverse impact on health, since they will reduce mucociliary clearance in vivo and slow down drug penetration to the bronchial epithelium during inhalation therapy.

  9. Fate and Transport of Nanoparticles in Porous Media: A Numerical Study

    Science.gov (United States)

    Taghavy, Amir

    Understanding the transport characteristics of NPs in natural soil systems is essential to revealing their potential impact on the food chain and groundwater. In addition, many nanotechnology-based remedial measures require effective transport of NPs through soil, which necessitates accurate understanding of their transport and retention behavior. Based upon the conceptual knowledge of environmental behavior of NPs, mathematical models can be developed to represent the coupling of processes that govern the fate of NPs in subsurface, serving as effective tools for risk assessment and/or design of remedial strategies. This work presents an innovative hybrid Eulerian-Lagrangian modeling technique for simulating the simultaneous reactive transport of nanoparticles (NPs) and dissolved constituents in porous media. Governing mechanisms considered in the conceptual model include particle-soil grain, particle-particle, particle-dissolved constituents, and particle- oil/water interface interactions. The main advantage of this technique, compared to conventional Eulerian models, lies in its ability to address non-uniformity in physicochemical particle characteristics. The developed numerical simulator was applied to investigate the fate and transport of NPs in a number of practical problems relevant to the subsurface environment. These problems included: (1) reductive dechlorination of chlorinated solvents by zero-valent iron nanoparticles (nZVI) in dense non-aqueous phase liquid (DNAPL) source zones; (2) reactive transport of dissolving silver nanoparticles (nAg) and the dissolved silver ions; (3) particle-particle interactions and their effects on the particle-soil grain interactions; and (4) influence of particle-oil/water interface interactions on NP transport in porous media.

  10. Transport Research Needs

    DEFF Research Database (Denmark)

    Ortúzar, Juan de Dios; Cherchi, Elisabetta; Rizzi, Luis

    2014-01-01

    Transport is a large, multidisciplinary and fascinating field, encompassing vastly different areas of research. In fact transport interests span from not very well understood (in fieldwork) issues related with survey methods to highly complex questions associated with the dynamic equilibration...... of supply and demand in strategic planning contexts; the latter involving large zoning systems, huge multimodal networks and highly complex dynamic modelling approaches (Mahmassani, 2001). But questions also arise at a more macro level (and in a different time span) regarding the interaction of transport....... For these reasons, in this chapter we will just concentrate on issues related with modelling the demand for travel in the relatively short term. In particular, we will refer to modelling discrete short-term choices, such as mode, route and/or trip timing; although in our analysis we will pay attention to research...

  11. Dynamic transport study of the plasmas with transport improvement in LHD and JT-60U

    International Nuclear Information System (INIS)

    Ida, K.; Inagaki, S.; Sakamoto, R.; Tanaka, K.; Funaba, H.; Kubo, S.; Yoshinuma, M.; Shimozuma, T.; Takeiri, Y.; Ikeda, K.; Michael, C.; Tokuzawa, T.; Sakamoto, Yoshiteru; Takenaga, Hidenobu; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki

    2006-10-01

    A transport analysis during the transient phase of heating (a dynamic transport study) applied to the plasma with internal transport barriers (ITBs) in the Large Helical Device (LHD) heliotron and JT-60U tokamak is described. In the dynamic transport study 1) a slow transition between two transport branches is observed, 2) the time of the transition from the L-mode plasma to the ITB plasma is clearly determined by the onset of the flattening of the temperature profile in the core region and 3) a spontaneous phase transition from a weak, wide ITB to a strong, narrow ITB and its back-transition are observed. The flattening of the core region of the ITB transition and the back-transition between a wide ITB and a narrow ITB suggest the strong interaction of turbulent transport in space, where turbulence suppression at certain locations in the plasma causes the enhancement of turbulence and thermal diffusivity nearby. (author)

  12. Serotonin transporter and dopamine transporter imaging in the canine brain

    International Nuclear Information System (INIS)

    Peremans, Kathelijne; Goethals, Ingeborg; De Vos, Filip; Dobbeleir, A.; Ham, Hamphrey; Van Bree, Henri; Heeringen, Cees van; Audenaert, Kurt

    2006-01-01

    The serotonergic and dopaminergic systems are involved in a wide range of emotional and behavioral aspects of animals and humans and are involved in many neuropsychiatric disorders. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are designed to block the 5-HT transporter (SERT), thereby increasing the available 5-HT in the brain. Functional imaging with specific SERT and dopamine transporter (DAT) ligands contributes to the study of the SSRI-transporter interaction. First, we evaluated the feasibility of a canine model in the study of the SERT and DAT with the radioligands [ 123 I]-β-CIT and [ 123 I]-FP-CIT as well as single-photon emission computed tomography imaging. Second, we studied the effect of SSRIs (sertraline, citalopram and escitalopram) on the SERT and DAT in two dogs. The position of the canine model in the study of the SERT and DAT is discussed and compared with other animal models

  13. Stochastic transport of particles across single barriers

    International Nuclear Information System (INIS)

    Kreuter, Christian; Siems, Ullrich; Henseler, Peter; Nielaba, Peter; Leiderer, Paul; Erbe, Artur

    2012-01-01

    Transport phenomena of interacting particles are of high interest for many applications in biology and mesoscopic systems. Here we present measurements on colloidal particles, which are confined in narrow channels on a substrate and interact with a barrier, which impedes the motion along the channel. The substrate of the particle is tilted in order for the particles to be driven towards the barrier and, if the energy gained by the tilt is large enough, surpass the barrier by thermal activation. We therefore study the influence of this barrier as well as the influence of particle interaction on the particle transport through such systems. All experiments are supported with Brownian dynamics simulations in order to complement the experiments with tests of a large range of parameter space which cannot be accessed in experiments.

  14. Genetically determined interaction between the dopamine transporter and the D2 receptor on prefronto-striatal activity and volume in humans.

    Science.gov (United States)

    Bertolino, Alessandro; Fazio, Leonardo; Di Giorgio, Annabella; Blasi, Giuseppe; Romano, Raffaella; Taurisano, Paolo; Caforio, Grazia; Sinibaldi, Lorenzo; Ursini, Gianluca; Popolizio, Teresa; Tirotta, Emanuele; Papp, Audrey; Dallapiccola, Bruno; Borrelli, Emiliana; Sadee, Wolfgang

    2009-01-28

    Dopamine modulation of neuronal activity during memory tasks identifies a nonlinear inverted-U shaped function. Both the dopamine transporter (DAT) and dopamine D(2) receptors (encoded by DRD(2)) critically regulate dopamine signaling in the striatum and in prefrontal cortex during memory. Moreover, in vitro studies have demonstrated that DAT and D(2) proteins reciprocally regulate each other presynaptically. Therefore, we have evaluated the genetic interaction between a DRD(2) polymorphism (rs1076560) causing reduced presynaptic D(2) receptor expression and the DAT 3'-VNTR variant (affecting DAT expression) in a large sample of healthy subjects undergoing blood oxygenation level-dependent (BOLD)-functional magnetic resonance imaging (MRI) during memory tasks and structural MRI. Results indicated a significant DRD(2)/DAT interaction in prefrontal cortex and striatum BOLD activity during both working memory and encoding of recognition memory. The differential effect on BOLD activity of the DAT variant was mostly manifest in the context of the DRD(2) allele associated with lower presynaptic expression. Similar results were also evident for gray matter volume in caudate. These interactions describe a nonlinear relationship between compound genotypes and brain activity or gray matter volume. Complementary data from striatal protein extracts from wild-type and D(2) knock-out animals (D2R(-/-)) indicate that DAT and D(2) proteins interact in vivo. Together, our results demonstrate that the interaction between genetic variants in DRD(2) and DAT critically modulates the nonlinear relationship between dopamine and neuronal activity during memory processing.

  15. The Particle Beam Optics Interactive Computer Laboratory

    International Nuclear Information System (INIS)

    Gillespie, G.H.; Hill, B.W.; Brown, N.A.; Babcock, R.C.; Martono, H.; Carey, D.C.

    1997-01-01

    The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) is an educational software concept to aid students and professionals in learning about charged particle beams and particle beam optical systems. The PBO Lab is being developed as a cross-platform application and includes four key elements. The first is a graphic user interface shell that provides for a highly interactive learning session. The second is a knowledge database containing information on electric and magnetic optics transport elements. The knowledge database provides interactive tutorials on the fundamental physics of charged particle optics and on the technology used in particle optics hardware. The third element is a graphical construction kit that provides tools for students to interactively and visually construct optical beamlines. The final element is a set of charged particle optics computational engines that compute trajectories, transport beam envelopes, fit parameters to optical constraints and carry out similar calculations for the student designed beamlines. The primary computational engine is provided by the third-order TRANSPORT code. Augmenting TRANSPORT is the multiple ray tracing program TURTLE and a first-order matrix program that includes a space charge model and support for calculating single particle trajectories in the presence of the beam space charge. This paper describes progress on the development of the PBO Lab. copyright 1997 American Institute of Physics

  16. An introduction to neutron transport

    International Nuclear Information System (INIS)

    Wiesenfeld, Bernard

    2015-01-01

    Neutron transport science is the study of neutron transport in a nuclear reactor and of associated nuclear reactions, notably fission reactions. Heat released by these reactions can be used for several purposes: electricity production, hydrogen production, sea water desalination, urban heating, naval propulsion, space propulsion, and so on. This publication contains the course proposed at Mines ParisTech and at the Arts et Metiers ParisTech. It is an introduction to neutron transport science and aims at presenting fundamental physical principles of this original branch of nuclear physics, a so called 'low energies' branch whereas 'high energy' nuclear physics focuses on elementary particles. It addresses complex computation methods which have been developed during the last decades with computation codes of always higher performance. The first part presents elements of atom physics: origin of matter, properties of nuclei and atoms, notion of quantum mechanics, interaction between radiation and matter (ray absorption, Compton Effect and scattering, photoelectric effect). The second part introduces neutron transport by addressing the following issues: nuclear structure, the various aspects of the interaction between neutrons and matter, the evolution of the reactivity of a reactor in normal operation, the chain fission reaction kinetics, and neutron slowing down. The third part addresses various aspects of neutron transport calculation: expression of neutron assessment, scattering approximation, critical condition of a nuclear reactor, introduction to transport theory, peculiarities of fast breeder reactors. The last chapter 'from theory to practice' addresses the approach of the neutron scientist, proposes an overview of the main calculation codes, and presents fields of application (within or without nuclear fission)

  17. Quantitative Analysis of Complex Drug-Drug Interactions Between Repaglinide and Cyclosporin A/Gemfibrozil Using Physiologically Based Pharmacokinetic Models With In Vitro Transporter/Enzyme Inhibition Data.

    Science.gov (United States)

    Kim, Soo-Jin; Toshimoto, Kota; Yao, Yoshiaki; Yoshikado, Takashi; Sugiyama, Yuichi

    2017-09-01

    Quantitative analysis of transporter- and enzyme-mediated complex drug-drug interactions (DDIs) is challenging. Repaglinide (RPG) is transported into the liver by OATP1B1 and then is metabolized by CYP2C8 and CYP3A4. The purpose of this study was to describe the complex DDIs of RPG quantitatively based on unified physiologically based pharmacokinetic (PBPK) models using in vitro K i values for OATP1B1, CYP3A4, and CYP2C8. Cyclosporin A (CsA) or gemfibrozil (GEM) increased the blood concentrations of RPG. The time profiles of RPG and the inhibitors were analyzed by PBPK models, considering the inhibition of OATP1B1 and CYP3A4 by CsA or OATP1B1 inhibition by GEM and its glucuronide and the mechanism-based inhibition of CYP2C8 by GEM glucuronide. RPG-CsA interaction was closely predicted using a reported in vitro K i,OATP1B1 value in the presence of CsA preincubation. RPG-GEM interaction was underestimated compared with observed data, but the simulation was improved with the increase of f m,CYP2C8 . These results based on in vitro K i values for transport and metabolism suggest the possibility of a bottom-up approach with in vitro inhibition data for the prediction of complex DDIs using unified PBPK models and in vitro f m value of a substrate for multiple enzymes should be considered carefully for the prediction. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  18. Zymosan-induced immune challenge modifies the stress response of hypoxic air-breathing fish (Anabas testudineus Bloch): Evidence for reversed patterns of cortisol and thyroid hormone interaction, differential ion transporter functions and non-specific immune response.

    Science.gov (United States)

    Simi, S; Peter, Valsa S; Peter, M C Subhash

    2017-09-15

    Fishes have evolved physiological mechanisms to exhibit stress response, where hormonal signals interact with an array of ion transporters and regulate homeostasis. As major ion transport regulators in fish, cortisol and thyroid hormones have been shown to interact and fine-tune the stress response. Likewise, in fishes many interactions have been identified between stress and immune components, but the physiological basis of such interaction has not yet delineated particularly in air-breathing fish. We, therefore, investigated the responses of thyroid hormones and cortisol, ion transporter functions and non-specific immune response of an obligate air-breathing fish Anabas testudineus Bloch to zymosan treatment or hypoxia stress or both, to understand how immune challenge modifies the pattern of stress response in this fish. Induction of experimental peritonitis in these fish by zymosan treatment (200ngg -1 ) for 24h produced rise in respiratory burst and lysozomal activities in head kidney phagocytes. In contrast, hypoxia stress for 30min in immune-challenged fish reversed these non-specific responses of head kidney phagocytes. The decline in plasma cortisol in zymosan-treated fish and its further suppression by hypoxia stress indicate that immune challenge suppresses the cortisol-driven stress response of this fish. Likewise, the decline in plasma T 3 and T 4 after zymosan-treatment and the rise in plasma T 4 after hypoxia stress in immune-challenged fish indicate a critical role for thyroid hormone in immune-stress response due to its differential sensitivity to both immune and stress challenges. Further, analysis of the activity pattern of ion-dependent ATPases viz. Na + /K + -ATPase, H + /K + -ATPase and Na + /NH 4 + -ATPase indicates a functional interaction of ion transport system with the immune response as evident in its differential and spatial modifications after hypoxia stress in immune-challenged fish. The immune-challenge that produced differential

  19. Transporter-mediated interaction of indican and methotrexate in rats

    Directory of Open Access Journals (Sweden)

    Shiuan-Pey Lin

    2018-04-01

    Full Text Available Indican (indoxyl-β-D-glucoside is present in several Chinese herbs e.g. Isatis indigotica, Polygonum tinctorium and Polygonum perfoliatum. The major metabolite of indican was indoxyl sulfate (IS, an uremic toxin which was a known substrate/inhibitor of organic anion transporter (OAT 1, OAT 3 and multidrug resistance-associated protein (MRP 4. Methotrexate (MTX, an important immunosuppressant with narrow therapeutic window, is a substrate of OAT 1, 2, 3, 4 and MRP 1, 2, 3, 4. We hypothesized that IS, the major metabolite of oral indican, might inhibit the renal excretion of MTX mediated by OAT 1, OAT 3 and MRP 4. Therefore, this study investigated the effect of oral indican on the pharmacokinetics of MTX. Rats were orally given MTX with and without indican (20.0 and 40.0 mg/kg in a parallel design. The serum MTX concentration was determined by a fluorescence polarization immunoassay. For mechanism clarification, phenolsulfonphthalein (PSP, 5.0 mg/kg, a probe substrate of OAT 1, OAT 3, MRP 2 and MRP 4, was intravenously given to rats with and without a intravenous bolus of IS (10.0 mg/kg to measure the effect of IS on the elimination of PSP. The results indicated that 20.0 and 40.0 mg/kg of oral indican significantly increased the area under concentration–time curve0-t (AUC0-t of MTX by 231% and 259%, prolonged the mean residence time (MRT by 223% and 204%, respectively. Furthermore, intravenous IS significantly increased the AUC0-t of PSP by 204% and decreased the Cl by 68%. In conclusion, oral indican increased the systemic exposure and MRT of MTX through inhibition on multiple anion transporters including OAT 1, OAT 3 and MRP 4 by the major metabolite IS. Keywords: Indican, Indoxyl sulfate, Methotrexate, Anion transporters, Pharmacokinetics

  20. Characterization of SLC transporters in human skin

    Directory of Open Access Journals (Sweden)

    Marion Alriquet

    2015-03-01

    Full Text Available Most identified drug transporters belong to the ATP-binding Cassette (ABC and Solute Carrier (SLC families. Recent research indicates that some of these transporters play an important role in the absorption, distribution and excretion of drugs, and are involved in clinically relevant drug-drug interactions for systemic drugs. However, very little is known about the role of drug transporters in human skin in the disposition of topically applied drugs and their involvement in drug-drug interactions. The aim of this work was to compare the expression in human skin (vs human hepatocytes and kidney of SLC transporters included in the EMA guidance as the most likely clinical sources of drug interactions. The expression of SLC transporters in human tissues was analyzed by quantitative RT-PCR. Modulation of SLC47A1 and SLC47A2 (MATE1 and MATE2 expression was analyzed after treatment of human skin in organ-culture with rifampicin and UV irradiation. The expression of SLCO2B1 (OATPB, SLCO3A1 (OATPD, SLCO4A1 (OATPE, SLC47A1 and SLC47A2 (MATE1 and MATE2 was detected in human skin, OATPE and MATE1 being the most expressed. OATPE is about 70 times more expressed in human skin than in human hepatocytes. Moreover, the expression of SLC47A1 and SLC47A2 was down-regulated after treatment with rifampicin or after exposure to UV light. The present findings demonstrate that SLCO4A1 (OATPE and SLC47A1 (MATE1 are highly expressed in human skin and suggest the involvement of SLC transporters in the disposition of topically applied drugs.

  1. Interfacial area transport in a confined Bubbly flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.; Sun, X.; Ishii, M. [Purdue Univ., Lafayette, IN (United States). School of Nuclear Engineering; Lincoln, F. [Bettis Atomic Power Lab., West Mifflin, Bechtel Bettis, Inc., PA (United States)

    2001-07-01

    The interfacial area transport equation applicable to the bubbly flow is presented. The model is evaluated against the data acquired in an adiabatic air-water upward two-phase flow loop with a test section of 20 cm in width and 1 cm in gap. In general, a good agreement, within the measurement error of {+-}10%, is observed for a wide range in the bubbly flow regime. The sensitivity analysis on the individual particle interaction mechanisms demonstrates the active interactions between the bubbles and highlights the mechanisms playing the dominant role in interfacial area transport. (author)

  2. Transport processes in space plasmas

    International Nuclear Information System (INIS)

    Birn, J.; Elphic, R.C.; Feldman, W.C.

    1997-01-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project represents a comprehensive research effort to study plasma and field transport processes relevant for solar-terrestrial interaction, involving the solar wind and imbedded magnetic field and plasma structures, the bow shock of the Earth's magnetosphere and associated waves, the Earth's magnetopause with imbedded flux rope structures and their connection with the Earth, plasma flow in the Earth's magnetotail, and ionospheric beam/wave interactions. The focus of the work was on the interaction between plasma and magnetic and electric fields in the regions where different plasma populations exist adjacent to or superposed on each other. These are the regions of particularly dynamic plasma behavior, important for plasma and energy transport and rapid energy releases. The research addressed questions about how this interaction takes place, what waves, instabilities, and particle/field interactions are involved, how the penetration of plasma and energy through characteristic boundaries takes place, and how the characteristic properties of the plasmas and fields of the different populations influence each other on different spatial and temporal scales. These topics were investigated through combining efforts in the analysis of plasma and field data obtained through space missions with theory and computer simulations of the plasma behavior

  3. ZnO nanoparticles modulate the ionic transport and voltage regulation of lysenin nanochannels.

    Science.gov (United States)

    Bryant, Sheenah L; Eixenberger, Josh E; Rossland, Steven; Apsley, Holly; Hoffmann, Connor; Shrestha, Nisha; McHugh, Michael; Punnoose, Alex; Fologea, Daniel

    2017-12-16

    The insufficient understanding of unintended biological impacts from nanomaterials (NMs) represents a serious impediment to their use for scientific, technological, and medical applications. While previous studies have focused on understanding nanotoxicity effects mostly resulting from cellular internalization, recent work indicates that NMs may interfere with transmembrane transport mechanisms, hence enabling contributions to nanotoxicity by affecting key biological activities dependent on transmembrane transport. In this line of inquiry, we investigated the effects of charged nanoparticles (NPs) on the transport properties of lysenin, a pore-forming toxin that shares fundamental features with ion channels such as regulation and high transport rate. The macroscopic conductance of lysenin channels greatly diminished in the presence of cationic ZnO NPs. The inhibitory effects were asymmetrical relative to the direction of the electric field and addition site, suggesting electrostatic interactions between ZnO NPs and a binding site. Similar changes in the macroscopic conductance were observed when lysenin channels were reconstituted in neutral lipid membranes, implicating protein-NP interactions as the major contributor to the reduced transport capabilities. In contrast, no inhibitory effects were observed in the presence of anionic SnO 2 NPs. Additionally, we demonstrate that inhibition of ion transport is not due to the dissolution of ZnO NPs and subsequent interactions of zinc ions with lysenin channels. We conclude that electrostatic interactions between positively charged ZnO NPs and negative charges within the lysenin channels are responsible for the inhibitory effects on the transport of ions. These interactions point to a potential mechanism of cytotoxicity, which may not require NP internalization.

  4. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton.

    Science.gov (United States)

    Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T; Tortell, Philippe D

    2015-01-01

    Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETR(RCII), mol e- mol RCII(-1) s(-1)) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal--oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETR(RCII): CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.

  5. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton.

    Directory of Open Access Journals (Sweden)

    Nina Schuback

    Full Text Available Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETR(RCII, mol e- mol RCII(-1 s(-1 increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal--oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETR(RCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.

  6. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton

    Science.gov (United States)

    Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T.; Tortell, Philippe D.

    2015-01-01

    Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETRRCII, mol e- mol RCII-1 s-1) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements. PMID:26171963

  7. Evaluation of the transporter-mediated herb-drug interaction potential of DA-9801, a standardized dioscorea extract for diabetic neuropathy, in human in vitro and rat in vivo.

    Science.gov (United States)

    Song, Im-Sook; Kong, Tae Yeon; Jeong, Hyeon-Uk; Kim, Eun Nam; Kwon, Soon-Sang; Kang, Hee Eun; Choi, Sang-Zin; Son, Miwon; Lee, Hye Suk

    2014-07-17

    Drug transporters play important roles in the absorption, distribution, and elimination of drugs and thereby, modulate drug efficacy and toxicity. With a growing use of poly pharmacy, concurrent administration of herbal extracts that modulate transporter activities with drugs can cause serious adverse reactions. Therefore, prediction and evaluation of drug-drug interaction potential is important in the clinic and in the drug development process. DA-9801, comprising a mixed extract of Dioscoreae rhizoma and Dioscorea nipponica Makino, is a new standardized extract currently being evaluated for diabetic peripheral neuropathy in a phase II clinical study. The inhibitory effects of DA-9801 on the transport functions of organic cation transporter (OCT)1, OCT2, organic anion transporter (OAT)1, OAT3, organic anion transporting polypeptide (OATP)1B1, OATP1B3, P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP) were investigated in HEK293 or LLC-PK1 cells. The effects of DA-9801 on the pharmacokinetics of relevant substrate drugs of these transporters were also examined in vivo in rats. DA-9801 inhibited the in vitro transport activities of OCT1, OCT2, OAT3, and OATP1B1, with IC50 values of 106, 174, 48.1, and 273 μg/mL, respectively, while the other transporters were not inhibited by 300 μg/mL DA-9801. To investigate whether this inhibitory effect of DA-9801 on OCT1, OCT2, and OAT3 could change the pharmacokinetics of their substrates in vivo, we measured the pharmacokinetics of cimetidine, a substrate for OCT1, OCT2, and OAT3, and of furosemide, a substrate for OAT1 and OAT3, by co-administration of DA-9801 at a single oral dose of 1,000 mg/kg. Pre-dose of DA-9801 5 min or 2 h prior to cimetidine administration decreased the Cmax of cimetidine in rats. However, DA-9801 did not affect the elimination parameters such as half-life, clearance, or amount excreted in the urine, suggesting that it did not inhibit elimination process of cimetidine, which is

  8. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    Science.gov (United States)

    Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.

    2016-03-01

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  9. Colloid transport in model fracture filling materials

    Science.gov (United States)

    Wold, S.; Garcia-Garcia, S.; Jonsson, M.

    2010-12-01

    Colloid transport in model fracture filling materials Susanna Wold*, Sandra García-García and Mats Jonsson KTH Chemical Science and Engineering Royal Institute of Technology, SE-100 44 Stockholm, Sweden *Corresponding author: E-mail: wold@kth.se Phone: +46 8 790 6295 In colloid transport in water-bearing fractures, the retardation depends on interactions with the fracture surface by sorption or filtration. These mechanisms are difficult to separate. A rougher surface will give a larger area available for sorption, and also when a particle is physically hindered, it approaches the surface and enables further sorption. Sorption can be explained by electrostatics were the strongest sorption on minerals always is observed at pH below pHpzc (Filby et al., 2008). The adhesion of colloids to mineral surfaces is related to the surface roughness according to a recent study (Darbha et al., 2010). There is a large variation in the characteristics of water-bearing fractures in bedrock in terms of aperture distribution, flow velocity, surface roughness, mineral distributions, presence of fracture filling material, and biological and organic material, which is hard to implement in modeling. The aim of this work was to study the transport of negatively charged colloids in model fracture filling material in relation to flow, porosity, mineral type, colloid size, and surface charge distribution. In addition, the impact on transport of colloids of mixing model fracture filling materials with different retention and immobilization capacities, determined by batch sorption experiments, was investigated. The transport of Na-montmorillonite colloids and well-defined negatively charged latex microspheres of 50, 100, and 200 nm diameter were studied in either columns containing quartz or quartz mixed with biotite. The ionic strength in the solution was exclusively 0.001 and pH 6 or 8.5. The flow rates used were 0.002, 0.03, and 0.6 mL min-1. Sorption of the colloids on the model fracture

  10. Planetary Surface-Atmosphere Interactions

    Science.gov (United States)

    Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.

    2013-09-01

    Planetary bodies having an accessible solid surface and significant atmosphere, such as Earth, Mars, Venus, Titan, share common phenomenology. Specifically wind induced transport of surface materials, subsequent erosion, the generation and transport of solid aerosols which leads both to chemical and electrostatic interaction with the atmosphere. How these processes affect the evolution of the atmosphere and surface will be discussed in the context of general planetology and the latest laboratory studies will be presented.

  11. LATTICE: an interactive lattice computer code

    International Nuclear Information System (INIS)

    Staples, J.

    1976-10-01

    LATTICE is a computer code which enables an interactive user to calculate the functions of a synchrotron lattice. This program satisfies the requirements at LBL for a simple interactive lattice program by borrowing ideas from both TRANSPORT and SYNCH. A fitting routine is included

  12. Strong Ligand-Protein Interactions Derived from Diffuse Ligand Interactions with Loose Binding Sites.

    Science.gov (United States)

    Marsh, Lorraine

    2015-01-01

    Many systems in biology rely on binding of ligands to target proteins in a single high-affinity conformation with a favorable ΔG. Alternatively, interactions of ligands with protein regions that allow diffuse binding, distributed over multiple sites and conformations, can exhibit favorable ΔG because of their higher entropy. Diffuse binding may be biologically important for multidrug transporters and carrier proteins. A fine-grained computational method for numerical integration of total binding ΔG arising from diffuse regional interaction of a ligand in multiple conformations using a Markov Chain Monte Carlo (MCMC) approach is presented. This method yields a metric that quantifies the influence on overall ligand affinity of ligand binding to multiple, distinct sites within a protein binding region. This metric is essentially a measure of dispersion in equilibrium ligand binding and depends on both the number of potential sites of interaction and the distribution of their individual predicted affinities. Analysis of test cases indicates that, for some ligand/protein pairs involving transporters and carrier proteins, diffuse binding contributes greatly to total affinity, whereas in other cases the influence is modest. This approach may be useful for studying situations where "nonspecific" interactions contribute to biological function.

  13. Serotonin transporter and dopamine transporter imaging in the canine brain

    Energy Technology Data Exchange (ETDEWEB)

    Peremans, Kathelijne [Department of Medical Imaging, Faculty of Veterinary Sciences, Ghent University, B-9000 Ghent (Belgium); Goethals, Ingeborg [Division of Nuclear Medicine, University Hospital Ghent, B-9000 Ghent (Belgium); De Vos, Filip [Laboratory of Radiopharmacy, Pharmaceutical Sciences, Ghent University, B-9000 Ghent (Belgium); Dobbeleir, A. [Department of Medical Imaging, Faculty of Veterinary Sciences, Ghent University, B-9000 Ghent (Belgium); Ham, Hamphrey [Division of Nuclear Medicine, University Hospital Ghent, B-9000 Ghent (Belgium); Van Bree, Henri [Department of Medical Imaging, Faculty of Veterinary Sciences, Ghent University, B-9000 Ghent (Belgium); Heeringen, Cees van [Department of Psychiatry and Medical Psychology, Faculty of Medical and Health Sciences, Ghent University, B-9000, Ghent (Belgium); Audenaert, Kurt [Division of Nuclear Medicine, University Hospital Ghent, B-9000 Ghent (Belgium) and Department of Psychiatry and Medical Psychology, Faculty of Medical and Health Sciences, Ghent University, B-9000, Ghent (Belgium)]. E-mail: kurt.audenaert@ugent.be

    2006-10-15

    The serotonergic and dopaminergic systems are involved in a wide range of emotional and behavioral aspects of animals and humans and are involved in many neuropsychiatric disorders. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are designed to block the 5-HT transporter (SERT), thereby increasing the available 5-HT in the brain. Functional imaging with specific SERT and dopamine transporter (DAT) ligands contributes to the study of the SSRI-transporter interaction. First, we evaluated the feasibility of a canine model in the study of the SERT and DAT with the radioligands [{sup 123}I]-{beta}-CIT and [{sup 123}I]-FP-CIT as well as single-photon emission computed tomography imaging. Second, we studied the effect of SSRIs (sertraline, citalopram and escitalopram) on the SERT and DAT in two dogs. The position of the canine model in the study of the SERT and DAT is discussed and compared with other animal models.

  14. SU-E-P-04: Transport Theory Learning Module in the Maple Environment

    Energy Technology Data Exchange (ETDEWEB)

    Both, J [University of Miami, Miller School of Medicine, Department of Radiation Oncology (United States)

    2014-06-01

    Purpose: The medical physics graduate program at the University of Miami is developing a computerized instructional module which provides an interactive mechanism for students to learn transport theory. While not essential in the medical physics curriculum, transport theory should be taught because the conceptual level of transport theory is fundamental, a substantial literature exists and ought to be accessible, and students should understand commercial software which solves the Boltzmann equation.But conventional teaching and learning of transport theory is challenging. Students may be under prepared to appreciate its methods, results, and relevance, and it is not substantially addressed in textbooks for the medical physicists. Other resources an instructor might reasonably use, while excellent, may be too briskly paced for beginning students. The purpose of this work is to render teaching of transport theory more tractable by making learning highly interactive. Methods: The module is being developed in the Maple mathematics environment by instructors and graduate students. It will refresh the students' knowledge of vector calculus and differential equations, and will develop users' intuition for phase space concepts. Scattering concepts will be developed with animated simulations using tunable parameters characterizing interactions, so that students may develop a “feel” for cross section. Transport equations for one and multiple types of radiation will be illustrated with phase space animations. Numerical methods of solution will be illustrated. Results: Attempts to teach rudiments of transport theory in radiation physics and dosimetry courses using conventional classroom techniques at the University of Miami have had small success, because classroom time is limited and the material has been hard for our students to appreciate intuitively. Conclusion: A joint effort of instructor and students to teach and learn transport theory by building an

  15. SU-E-P-04: Transport Theory Learning Module in the Maple Environment

    International Nuclear Information System (INIS)

    Both, J

    2014-01-01

    Purpose: The medical physics graduate program at the University of Miami is developing a computerized instructional module which provides an interactive mechanism for students to learn transport theory. While not essential in the medical physics curriculum, transport theory should be taught because the conceptual level of transport theory is fundamental, a substantial literature exists and ought to be accessible, and students should understand commercial software which solves the Boltzmann equation.But conventional teaching and learning of transport theory is challenging. Students may be under prepared to appreciate its methods, results, and relevance, and it is not substantially addressed in textbooks for the medical physicists. Other resources an instructor might reasonably use, while excellent, may be too briskly paced for beginning students. The purpose of this work is to render teaching of transport theory more tractable by making learning highly interactive. Methods: The module is being developed in the Maple mathematics environment by instructors and graduate students. It will refresh the students' knowledge of vector calculus and differential equations, and will develop users' intuition for phase space concepts. Scattering concepts will be developed with animated simulations using tunable parameters characterizing interactions, so that students may develop a “feel” for cross section. Transport equations for one and multiple types of radiation will be illustrated with phase space animations. Numerical methods of solution will be illustrated. Results: Attempts to teach rudiments of transport theory in radiation physics and dosimetry courses using conventional classroom techniques at the University of Miami have had small success, because classroom time is limited and the material has been hard for our students to appreciate intuitively. Conclusion: A joint effort of instructor and students to teach and learn transport theory by building an interactive

  16. Surface Effect on Oil Transportation in Nanochannel: a Molecular Dynamics Study.

    Science.gov (United States)

    Zheng, Haixia; Du, Yonggang; Xue, Qingzhong; Zhu, Lei; Li, Xiaofang; Lu, Shuangfang; Jin, Yakang

    2017-12-01

    In this work, we investigate the dynamics mechanism of oil transportation in nanochannel using molecular dynamics simulations. It is demonstrated that the interaction between oil molecules and nanochannel has a great effect on the transportation properties of oil in nanochannel. Because of different interactions between oil molecules and channel, the center of mass (COM) displacement of oil in a 6-nm channel is over 30 times larger than that in a 2-nm channel, and the diffusion coefficient of oil molecules at the center of a 6-nm channel is almost two times more than that near the channel surface. Besides, it is found that polarity of oil molecules has the effect on impeding oil transportation, because the electrostatic interaction between polar oil molecules and channel is far larger than that between nonpolar oil molecules and channel. In addition, channel component is found to play an important role in oil transportation in nanochannel, for example, the COM displacement of oil in gold channel is very few due to great interaction between oil and gold substrate. It is also found that nano-sized roughness of channel surface greatly influences the speed and flow pattern of oil. Our findings would contribute to revealing the mechanism of oil transportation in nanochannels and therefore are very important for design of oil extraction in nanochannels.

  17. Transport properties of chiral fermions

    Energy Technology Data Exchange (ETDEWEB)

    Puhr, Matthias

    2017-04-26

    Anomalous transport phenomena have their origin in the chiral anomaly, the anomalous non-conservation of the axial charge, and can arise in systems with chiral fermions. The anomalous transport properties of free fermions are well understood, but little is known about possible corrections to the anomalous transport coefficients that can occur if the fermions are strongly interacting. The main goal of this thesis is to study anomalous transport effects in media with strongly interacting fermions. In particular, we investigate the Chiral Magnetic Effect (CME) in a Weyl Semimetal (WSM) and the Chiral Separation Effect (CSE) in finite-density Quantum Chromodynamics (QCD). The recently discovered WSMs are solid state crystals with low-energy excitations that behave like Weyl fermions. The inter-electron interaction in WSMs is typically very strong and non-perturbative calculations are needed to connect theory and experiment. To realistically model an interacting, parity-breaking WSM we use a tight-binding lattice Hamiltonian with Wilson-Dirac fermions. This model features a non-trivial phase diagram and has a phase (Aoki phase/axionic insulator phase) with spontaneously broken CP symmetry, corresponding to the phase with spontaneously broken chiral symmetry for interacting continuum Dirac fermions. We use a mean-field ansatz to study the CME in spatially modulated magnetic fields and find that it vanishes in the Aoki phase. Moreover, our calculations show that outside of the Aoki phase the electron interaction has only a minor influence on the CME. We observe no enhancement of the magnitude of the CME current. For our non-perturbative study of the CSE in QCD we use the framework of lattice QCD with overlap fermions. We work in the quenched approximation to avoid the sign problem that comes with introducing a finite chemical potential on the lattice. The overlap operator calls for the evaluation of the sign function of a matrix with a dimension proportional to the volume

  18. Correlations and symmetry of interactions influence collective dynamics of molecular motors

    International Nuclear Information System (INIS)

    Celis-Garza, Daniel; Teimouri, Hamid; Kolomeisky, Anatoly B

    2015-01-01

    Enzymatic molecules that actively support many cellular processes, including transport, cell division and cell motility, are known as motor proteins or molecular motors. Experimental studies indicate that they interact with each other and they frequently work together in large groups. To understand the mechanisms of collective behavior of motor proteins we study the effect of interactions in the transport of molecular motors along linear filaments. It is done by analyzing a recently introduced class of totally asymmetric exclusion processes that takes into account the intermolecular interactions via thermodynamically consistent approach. We develop a new theoretical method that allows us to compute analytically all dynamic properties of the system. Our analysis shows that correlations play important role in dynamics of interacting molecular motors. Surprisingly, we find that the correlations for repulsive interactions are weaker and more short-range than the correlations for the attractive interactions. In addition, it is shown that symmetry of interactions affect dynamic properties of molecular motors. The implications of these findings for motor proteins transport are discussed. Our theoretical predictions are tested by extensive Monte Carlo computer simulations. (paper)

  19. Epithelial transport in The Journal of General Physiology.

    Science.gov (United States)

    Palmer, Lawrence G

    2017-10-02

    Epithelia define the boundaries of the body and often transfer solutes and water from outside to inside (absorption) or from inside to outside (secretion). Those processes involve dual plasma membranes with different transport components that interact with each other. Understanding those functions has entailed breaking down the problem to analyze properties of individual membranes (apical vs. basolateral) and individual transport proteins. It also requires understanding of how those components interact and how they are regulated. This article outlines the modern history of this research as reflected by publications in The Journal of General Physiology . © 2017 Palmer.

  20. A study of fast electron energy transport in relativistically intense laser-plasma interactions with large density scalelengths

    Energy Technology Data Exchange (ETDEWEB)

    Scott, R. H. H.; Norreys, P. A. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Perez, F.; Baton, S. D. [LULI, Ecole Polytechnique, UMR 7605, CNRS/CEA/UPMC, Route de Saclay, 91128 Palaiseau (France); Santos, J. J.; Nicolai, Ph.; Hulin, S. [Univ. Bordeaux/CNRS/CEA, CELIA, UMR 5107, 33405 Talence (France); Ridgers, C. P. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Davies, J. R. [GoLP, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Lancaster, K. L.; Trines, R. M. G. M. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Bell, A. R.; Tzoufras, M. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Rose, S. J. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom)

    2012-05-15

    A systematic experimental and computational investigation of the effects of three well characterized density scalelengths on fast electron energy transport in ultra-intense laser-solid interactions has been performed. Experimental evidence is presented which shows that, when the density scalelength is sufficiently large, the fast electron beam entering the solid-density plasma is best described by two distinct populations: those accelerated within the coronal plasma (the fast electron pre-beam) and those accelerated near or at the critical density surface (the fast electron main-beam). The former has considerably lower divergence and higher temperature than that of the main-beam with a half-angle of {approx}20 Degree-Sign . It contains up to 30% of the total fast electron energy absorbed into the target. The number, kinetic energy, and total energy of the fast electrons in the pre-beam are increased by an increase in density scalelength. With larger density scalelengths, the fast electrons heat a smaller cross sectional area of the target, causing the thinnest targets to reach significantly higher rear surface temperatures. Modelling indicates that the enhanced fast electron pre-beam associated with the large density scalelength interaction generates a magnetic field within the target of sufficient magnitude to partially collimate the subsequent, more divergent, fast electron main-beam.

  1. Quantum Transport Through Tunable Molecular Diodes

    KAUST Repository

    Obodo, Tobechukwu Joshua; Murat, Altynbek; Schwingenschlö gl, Udo

    2017-01-01

    Employing self-interaction corrected density functional theory combined with the non-equilibrium Green's function method, we study the quantum transport through molecules with different numbers of phenyl (donor) and pyrimidinyl (acceptor) rings

  2. Public transport optimisation emphasising passengers’ travel behaviour

    DEFF Research Database (Denmark)

    Jensen, Jens Parbo

    to the case where the two problems are solved sequentially without taking into account interdependencies. Figure 1 - Planning public transport The PhD study develops a metaheuristic algorithm to adapt the line plan configuration in order better to match passengers’ travel demand in terms of transfers as well......Passengers in public transport complaining about their travel experiences are not uncommon. This might seem counterintuitive since several operators worldwide are presenting better key performance indicators year by year. The present PhD study focuses on developing optimisation algorithms...... to enhance the operations of public transport while explicitly emphasising passengers’ travel behaviour and preferences. Similar to economic theory, interactions between supply and demand are omnipresent in the context of public transport operations. In public transport, the demand is represented...

  3. Phonon limited electronic transport in Pb

    Science.gov (United States)

    Rittweger, F.; Hinsche, N. F.; Mertig, I.

    2017-09-01

    We present a fully ab initio based scheme to compute electronic transport properties, i.e. the electrical conductivity σ and thermopower S, in the presence of electron-phonon interaction. We explicitly investigate the \

  4. Calmodulin kinase II interacts with the dopamine transporter C terminus to regulate amphetamine-induced reverse transport

    DEFF Research Database (Denmark)

    Fog, Jacob U; Khoshbouei, Habibeh; Holy, Marion

    2006-01-01

    Efflux of dopamine through the dopamine transporter (DAT) is critical for the psychostimulatory properties of amphetamines, but the underlying mechanism is unclear. Here we show that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) plays a key role in this efflux. CaMKIIalpha bound to the d...

  5. Structure/functional aspects of the human riboflavin transporter-3 (SLC52A3): role of the predicted glycosylation and substrate-interacting sites.

    Science.gov (United States)

    Subramanian, Veedamali S; Sabui, Subrata; Teafatiller, Trevor; Bohl, Jennifer A; Said, Hamid M

    2017-08-01

    The human riboflavin (RF) transporter-3 (hRFVT-3; product of the SLC52A3 gene) plays an essential role in the intestinal RF absorption process and is expressed exclusively at the apical membrane domain of polarized enterocytes. Previous studies have characterized different physiological/biological aspects of this transporter, but nothing is known about the glycosylation status of the hRFVT-3 protein and role of this modification in its physiology/biology. Additionally, little is known about the residues in the hRFVT-3 protein that interact with the ligand, RF. We addressed these issues using appropriate biochemical/molecular approaches, a protein-docking model, and established intestinal/renal epithelial cells. Our results showed that the hRFVT-3 protein is glycosylated and that glycosylation is important for its function. Mutating the predicted N -glycosylation sites at Asn 94 and Asn 168 led to a significant decrease in RF uptake; it also led to a marked intracellular (in the endoplasmic reticulum, ER) retention of the mutated proteins as shown by live-cell confocal imaging studies. The protein-docking model used in this study has identified a number of putative substrate-interacting sites: Ser 16 , Ile 20 , Trp 24 , Phe 142 , Thr 314 , and Asn 315 Mutating these potential interacting sites was indeed found to lead to a significant inhibition in RF uptake and to intracellular (ER) retention of the mutated proteins (except for the Phe 142 mutant). These results demonstrate that the hRFVT-3 protein is glycosylated and this glycosylation is important for its function and cell surface expression. This study also identified a number of residues in the hRFVT-3 polypeptide that are important for its function/cell surface expression.

  6. Quantitative Rationalization of Gemfibrozil Drug Interactions: Consideration of Transporters-Enzyme Interplay and the Role of Circulating Metabolite Gemfibrozil 1-O-β-Glucuronide.

    Science.gov (United States)

    Varma, Manthena V S; Lin, Jian; Bi, Yi-an; Kimoto, Emi; Rodrigues, A David

    2015-07-01

    Gemfibrozil has been suggested as a sensitive cytochrome P450 2C8 (CYP2C8) inhibitor for clinical investigation by the U.S. Food and Drug Administration and the European Medicines Agency. However, gemfibrozil drug-drug interactions (DDIs) are complex; its major circulating metabolite, gemfibrozil 1-O-β-glucuronide (Gem-Glu), exhibits time-dependent inhibition of CYP2C8, and both parent and metabolite also behave as moderate inhibitors of organic anion transporting polypeptide 1B1 (OATP1B1) in vitro. Additionally, parent and metabolite also inhibit renal transport mediated by OAT3. Here, in vitro inhibition data for gemfibrozil and Gem-Glu were used to assess their impact on the pharmacokinetics of several victim drugs (including rosiglitazone, pioglitazone, cerivastatin, and repaglinide) by employing both static mechanistic and dynamic physiologically based pharmacokinetic (PBPK) models. Of the 48 cases evaluated using the static models, about 75% and 98% of the DDIs were predicted within 1.5- and 2-fold of the observed values, respectively, when incorporating the interaction potential of both gemfibrozil and its 1-O-β-glucuronide. Moreover, the PBPK model was able to recover the plasma profiles of rosiglitazone, pioglitazone, cerivastatin, and repaglinide under control and gemfibrozil treatment conditions. Analyses suggest that Gem-Glu is the major contributor to the DDIs, and its exposure needed to bring about complete inactivation of CYP2C8 is only a fraction of that achieved in the clinic after a therapeutic gemfibrozil dose. Overall, the complex interactions of gemfibrozil can be quantitatively rationalized, and the learnings from this analysis can be applied in support of future predictions of gemfibrozil DDIs. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  7. Drug-permeability and transporter assays in Caco-2 and MDCK cell lines.

    Science.gov (United States)

    Volpe, Donna A

    2011-12-01

    The human colon adenocarcinoma Caco-2 and Madin-Darby canine kidney epithelial cell lines provide in vitro tools to assess a drug's permeability and transporter interactions during discovery and development. The cells, when cultured on semiporous filters, form confluent monolayers that model the intestinal epithelial barrier for permeability, transporter and drug-interaction assays. The applications of these assays in pharmaceutical research include qualitative prediction and ranking of absorption, determining mechanism(s) of permeability, formulation effects on drug permeability, and the potential for transporter-mediated drug-drug interactions. This review focuses on recent examples of Caco-2 and Madin-Darby canine kidney cells assays for drug permeability including transfected and knock-down cells, miniaturization and automation, and assay combinations to better understand and predict intestinal drug absorption.

  8. ABC transporters from Botrytis cinerea in biotic and abiotic interactions

    NARCIS (Netherlands)

    Schoonbeek, H.

    2004-01-01

    Botrytis cinereais the causal agent of grey mould disease on a wide variety of crop plants. It is relatively insensitive to natural and synthetic fungitoxic compounds. This thesis describes how ABC (ATP-binding cassette) transporters contribute to protection by actively

  9. Recent advances in the understanding of the interaction of antidepressant drugs with serotonin and norepinephrine transporters

    DEFF Research Database (Denmark)

    Andersen, Jacob; Kristensen, Anders Skov; Bang-Andersen, Benny

    2009-01-01

    The biogenic monoamine transporters are integral membrane proteins that perform active transport of extracellular dopamine, serotonin and norepinephrine into cells. These transporters are targets for therapeutic agents such as antidepressants, as well as addictive substances such as cocaine...... and amphetamine. Seminal advances in the understanding of the structure and function of this transporter family have recently been accomplished by structural studies of a bacterial transporter, as well as medicinal chemistry and pharmacological studies of mammalian transporters. This feature article focuses...

  10. Interactions between crude drug extracts used in Japanese traditional Kampo medicines and organic anion-transporting polypeptide 2B1.

    Science.gov (United States)

    Iijima, Rie; Watanabe, Tomoki; Ishiuchi, Kan'ichiro; Matsumoto, Takashi; Watanabe, Junko; Makino, Toshiaki

    2018-03-25

    The use of herbal medicines has become popular worldwide, and the information on drug interactions between herbal medicines and chemical drugs is needed. We screened the inhibitory effects of crude drugs used in Kampo medicines used in Japan on organic anion-transporting polypeptide (OATP) 2B1 to predict potential interactions between Kampo medicines and chemical drugs used together. We chose 98 kinds of crude drugs frequently used as ingredients of Kampo formulations in Japan and prepared their boiling water extracts. We then screened their inhibitory effects on OATP2B1 by measuring the uptake of estrone 3-sulphate (E3S) by HEK293 cells stably expressing OATP2B1. At the concentration of 100µg/ml, the extracts prepared from 12 kinds of crude drugs, Scuteralliae Radix, Arecae Semen, Aurantii Fructus Immaturus, Perillae Herba, Panacis Japonici Rhizoma, Moutan Cortex, Polygalae Radix, Rhei Rhizoma, Cannabis Fructus, Chrysanthemi Flos, Eriobotryae Folium, and Querci Cortex, suppressed the function of OATP2B1 by less than 20%. The extract of bofutsushosan, a representative Kampo formulation, inhibited OATP2B1 function with sufficient levels to suppress absorption of OATP2B1 substrates in clinics. We further evaluated the inhibitory effects of several ingredients containing Rhei Rhizoma, Perillae Herba, and Moutan Cortex on OATP2B1. Because of crude drugs used in Kampo medicines might suppress absorption of OATP2B1 substrates, these results may contribute to the safe and effective use of Kampo medicine in clinics. A list of abbreviations: EC, (-)-epicatechin; ECG, epicatechin gallate; EGC, epigallocatechin; EGCG, Epigallocatechin gallate; FBS, fetal bovine serum; grapefruit juice; HEK293, Human embryonic kidney; IC 50, The half inhibitory concentration; OATP, organic anion-transporting polypeptide; β-PGG, penta-O-galloyl-β-D-glucose; t.i.d, 3 times a day. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Advanced Monte Carlo for radiation physics, particle transport simulation and applications. Proceedings

    International Nuclear Information System (INIS)

    Kling, A.; Barao, F.J.C.; Nakagawa, M.; Tavora, L.

    2001-01-01

    The following topics were dealt with: Electron and photon interactions and transport mechanisms, random number generation, applications in medical physisc, microdosimetry, track structure, radiobiological modeling, Monte Carlo method in radiotherapy, dosimetry, and medical accelerator simulation, neutron transport, high-energy hadron transport. (HSI)

  12. Modified Monte Carlo method for study of electron transport in degenerate electron gas in the presence of electron–electron interactions, application to graphene

    International Nuclear Information System (INIS)

    Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek

    2017-01-01

    Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of electron transport in semiconductors may give unphysical results in low field regime, where obtained electron distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for electron scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for electron–electron (e–e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the electron distribution function. Proposed algorithm is applied to study transport properties of degenerate electrons in graphene with e–e interactions. This required adapting the treatment of e–e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.

  13. Modified Monte Carlo method for study of electron transport in degenerate electron gas in the presence of electron-electron interactions, application to graphene

    Science.gov (United States)

    Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek

    2017-07-01

    Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of electron transport in semiconductors may give unphysical results in low field regime, where obtained electron distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for electron scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for electron-electron (e-e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the electron distribution function. Proposed algorithm is applied to study transport properties of degenerate electrons in graphene with e-e interactions. This required adapting the treatment of e-e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.

  14. Modified Monte Carlo method for study of electron transport in degenerate electron gas in the presence of electron–electron interactions, application to graphene

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Piotr, E-mail: pborow@poczta.onet.pl [Warsaw University of Technology, Faculty of Physics, ul. Koszykowa 75, 00-662 Warszawa (Poland); Thobel, Jean-Luc, E-mail: jean-luc.thobel@iemn.univ-lille1.fr [Institut d' Electronique, de Microélectronique et de Nanotechnologies, UMR CNRS 8520, Université Lille 1, Avenue Poincaré, CS 60069, 59652 Villeneuve d' Ascq Cédex (France); Adamowicz, Leszek, E-mail: adamo@if.pw.edu.pl [Warsaw University of Technology, Faculty of Physics, ul. Koszykowa 75, 00-662 Warszawa (Poland)

    2017-07-15

    Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of electron transport in semiconductors may give unphysical results in low field regime, where obtained electron distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for electron scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for electron–electron (e–e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the electron distribution function. Proposed algorithm is applied to study transport properties of degenerate electrons in graphene with e–e interactions. This required adapting the treatment of e–e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.

  15. Critical review: Radionuclide transport, sediment transport, and water quality mathematical modeling; and radionuclide adsorption/desorption mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Y.; Serne, R.J.; Arnold, E.M.; Cowan, C.E.; Thompson, F.L. [Pacific Northwest Lab., Richland, WA (United States)

    1981-01-01

    This report describes the results of a detailed literature review of radionuclide transport models applicable to rivers, estuaries, coastal waters, the Great Lakes, and impoundments. Some representatives sediment transport and water quality models were also reviewed to evaluate if they can be readily adapted to radionuclide transport modeling. The review showed that most available transport models were developed for dissolved radionuclide in rivers. These models include the mechanisms of advection, dispersion, and radionuclide decay. Since the models do not include sediment and radionuclide interactions, they are best suited for simulating short-term radionuclide migration where: (1) radionuclides have small distribution coefficients; (2) sediment concentrations in receiving water bodies are very low. Only 5 of the reviewed models include full sediment and radionuclide interactions: CHMSED developed by Fields; FETRA SERATRA, and TODAM developed by Onishi et al, and a model developed by Shull and Gloyna. The 5 models are applicable to cases where: (1) the distribution coefficient is large; (2) sediment concentrations are high; or (3) long-term migration and accumulation are under consideration. The report also discusses radionuclide absorption/desorption distribution ratios and addresses adsorption/desorption mechanisms and their controlling processes for 25 elements under surface water conditions. These elements are: Am, Sb, C, Ce, Cm, Co, Cr, Cs, Eu, I, Fe, Mn, Np, P, Pu, Pm, Ra, Ru, Sr, Tc, Th, {sup 3}H, U, Zn and Zr.

  16. Public transport optimisation emphasising passengers’ travel behaviour.

    OpenAIRE

    Jensen, Jens Parbo; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2015-01-01

    Passengers in public transport complaining about their travel experiences are not uncommon. This might seem counterintuitive since several operators worldwide are presenting better key performance indicators year by year. The present PhD study focuses on developing optimisation algorithms to enhance the operations of public transport while explicitly emphasising passengers’ travel behaviour and preferences. Similar to economic theory, interactions between supply and demand are omnipresent in ...

  17. Lipid-protein interactions. The leucine transport system of Lactococcus lactis.

    NARCIS (Netherlands)

    Veld, Geertruida Elisabeth in 't

    1992-01-01

    In summary, it is concluded, that a functionally reconstituted leucine transport system of L. lactis is affected by bilayer features in the following order of importance: lipid headgroup (H+-bonding) › acyl chain carbon number (thickness) › cholesterol (fluidity) › acyl chain unsaturation (indirect

  18. In-stream contaminant interaction and transport

    International Nuclear Information System (INIS)

    Whelan, G.

    1983-07-01

    In order to assess contaminant exposure levels in biotic and abiotic pathways from waste-disposal sites, a comprehensive Multimedia Contaminant Environmental Exposure Assessment (MCEA) methodology using several mathematical models is being developed. Prior to a full development of the proposed methodology, a scaled-down version involving terrestrial plants, overland, and in-stream compartments was applied to an actual shallow land waste-disposal site. The purpose was to evaluate and demonstrate the attributes of the methodology. The in-stream component of the abbreviated methodology as it relates to Mortandad Canyon in Los Alamos, New Mexico is discussed herein. A two-year period was simulated consisting of six major runoff events which possessed a variety of distributions and magnitudes. The in-stream component of the methodology was composed of two models integrated to simulate the migration of radionuclides: DKWAV and TODAM. DKWAV is an unsteady, one-dimensional, second-order, explicit, finite difference, channel flow code which simulates the hydrodynamics in dendritric river systems and includes point and/or continuous lateral inflow and channel seepage. TODAM is an unsteady, one-dimensional, finite element, sediment-contaminant transport code which simulates the migration and fate of sediment and radionuclides in their dissolved and particulate phases by solving the general advection/diffusion equation with sink and source terms

  19. Anomalous transport of magnetized electrons interacting with EC waves

    Energy Technology Data Exchange (ETDEWEB)

    Tsironis, C; Vlahos, L [Section of Astrophysics, Astronomy and Mechanics, Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2005-01-01

    We consider the nonlinear interaction of magnetized electrons with an oblique narrow-band electromagnetic wave-packet. The interaction is analysed over and near the local threshold to chaos. The statistical character of the forcing that controls the trajectories of the particles is also studied. We focus our analysis on issues related to energy and spatial diffusion across the magnetic field by following the evolution of the ensemble mean squares (({gamma} - {gamma}{sub 0}){sup 2}) and ((r{sub perpendicular}-r{sub perpendicular0}){sup 2}) for various values of the wave amplitude and angle of wave propagation. We study, in particular, the interaction of magnetized electrons with waves having strong and moderate amplitudes, near the transition to chaos, where the dynamics is complex and a mixture of periodic and stochastic orbits coexist. The electron diffusions in real and energy spaces are found to obey simple power laws in time, and the scaling exponents are indicative of sub-diffusion. This is a direct consequence of the effect of the resonant phase-space islands in the particle motion.

  20. 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.

  1. New trends in mechanics and transport

    CERN Document Server

    Uhl, Tadeusz

    2007-01-01

    Nowadays, one of the most rapidly growing sectors of industry is that of the infrastructure and vehicles of transportation systems. This discipline needs new, innovative and economically proven initiatives.The domain of transport is an interdisciplinary one which brings together many different scientific and engineering strands. The synergy between mechanics and transportation science offers the possibility of finding new and effective solutions to design, manufacturing and servicing problems. Due to globalization of the market-place, international cooperation in applied research is very fruitful and expedient.This collection of 13 refereed papers is the result of a unique opportunity offered to the scientific and technical communities for them to interact and to consolidate the application of current achievements in mechanical science as applied to transport. It covers topics which include theoretical, numerical and experimental studies of transport-related areas. All-in-all, it represents a succinct state-o...

  2. Academic Training - The use of Monte Carlo radiation transport codes in radiation physics and dosimetry

    CERN Multimedia

    Françoise Benz

    2006-01-01

    2005-2006 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 27, 28, 29 June 11:00-12:00 - TH Conference Room, bldg. 4 The use of Monte Carlo radiation transport codes in radiation physics and dosimetry F. Salvat Gavalda,Univ. de Barcelona, A. FERRARI, CERN-AB, M. SILARI, CERN-SC Lecture 1. Transport and interaction of electromagnetic radiation F. Salvat Gavalda,Univ. de Barcelona Interaction models and simulation schemes implemented in modern Monte Carlo codes for the simulation of coupled electron-photon transport will be briefly reviewed. Different schemes for simulating electron transport will be discussed. Condensed algorithms, which rely on multiple-scattering theories, are comparatively fast, but less accurate than mixed algorithms, in which hard interactions (with energy loss or angular deflection larger than certain cut-off values) are simulated individually. The reliability, and limitations, of electron-interaction models and multiple-scattering theories will be analyzed. Benchmark comparisons of simu...

  3. Resonance controlled transport in phase space

    Science.gov (United States)

    Leoncini, Xavier; Vasiliev, Alexei; Artemyev, Anton

    2018-02-01

    We consider the mechanism of controlling particle transport in phase space by means of resonances in an adiabatic setting. Using a model problem describing nonlinear wave-particle interaction, we show that captures into resonances can be used to control transport in momentum space as well as in physical space. We design the model system to provide creation of a narrow peak in the distribution function, thus producing effective cooling of a sub-ensemble of the particles.

  4. Experimental studies and modelling of cation interactions with solid materials: application to the MIMICC project. (Multidimensional Instrumented Module for Investigations on chemistry-transport Coupled Codes)

    International Nuclear Information System (INIS)

    Hardin, Emmanuelle

    1999-01-01

    The study of cation interactions with solid materials is useful in order to define the chemistry interaction component of the MIMICC project (Multidimensional Instrumented Module for Investigations on chemistry-transport Coupled Codes). This project will validate the chemistry-transport coupled codes. Database have to be supplied on the cesium or ytterbium interactions with solid materials in suspension. The solid materials are: a strong cation exchange resin, a natural sand which presents small impurities, and a zirconium phosphate. The cation exchange resin is useful to check that the surface complexation theory can be applied on a pure cation exchanger. The sand is a natural material, and its isotherms will be interpreted using pure oxide-cation system data, such as pure silica-cation data. Then the study on the zirconium phosphate salt is interesting because of the increasing complexity in the processes (dissolution, sorption and co-precipitation). These data will enable to approach natural systems, constituted by several complex solids which can interfere on each other. These data can also be used for chemistry-transport coupled codes. Potentiometric titration, sorption isotherms, sorption kinetics, cation surface saturation curves are made, in order to obtain the different parameters relevant to the cation sorption at the solid surface, for each solid-electrolyte-cation system. The influence of different parameters such as ionic strength, pH, and electrolyte is estimated. All the experimental curves are fitted with FITEQL code based on the surface complexation theory using the constant capacitance model, in order to give a mechanistic interpretation of the ion retention phenomenon at the solid surface. The speciation curves of all systems are plotted, using the FITEQL code too. Systems with an increasing complexity are studied: dissolution, sorption and coprecipitation coexist in the cation-salt systems. Then the data obtained on each single solid, considered

  5. Sugar and Glycerol Transport in Saccharomyces cerevisiae.

    Science.gov (United States)

    Bisson, Linda F; Fan, Qingwen; Walker, Gordon A

    2016-01-01

    In Saccharomyces cerevisiae the process of transport of sugar substrates into the cell comprises a complex network of transporters and interacting regulatory mechanisms. Members of the large family of hexose (HXT) transporters display uptake efficiencies consistent with their environmental expression and play physiological roles in addition to feeding the glycolytic pathway. Multiple glucose-inducing and glucose-independent mechanisms serve to regulate expression of the sugar transporters in yeast assuring that expression levels and transporter activity are coordinated with cellular metabolism and energy needs. The expression of sugar transport activity is modulated by other nutritional and environmental factors that may override glucose-generated signals. Transporter expression and activity is regulated transcriptionally, post-transcriptionally and post-translationally. Recent studies have expanded upon this suite of regulatory mechanisms to include transcriptional expression fine tuning mediated by antisense RNA and prion-based regulation of transcription. Much remains to be learned about cell biology from the continued analysis of this dynamic process of substrate acquisition.

  6. Mechanism of ochratoxin A transport in kidney

    International Nuclear Information System (INIS)

    Sokol, P.P.; Ripich, G.; Holohan, P.D.; Ross, C.R.

    1988-01-01

    The effect of the fungal metabolite (mycotoxin) Ochratoxin A (OTA) on the transport of p-amino[ 3 H]hippurate (PAH), a prototypic organic anion, was examined in renal brush border (BBMV) and basolateral membrane vesicles (BLMV). OTA was as effective an inhibitor of PAH uptake in both membranes as probenecid. The dose response curves for OTA in BBMV and BLMV gave IC50 values of 20 +/- 6 and 32 +/- 7 microM, respectively. The effect was specific since the transport of the organic cation N1-methylnicotinamide was not affected. The phenomenon of counterflow was studied to establish that OTA is translocated. OTA produced trans stimulation of PAH transport in both BBMV and BLMV, demonstrating that OTA is transported across both these membranes. The data suggest that OTA interacts with the PAH transport system in both BBMV and BLMV. We conclude that OTA transport in the kidney is mediated via the renal organic anion transport system

  7. Effect of finite Coulomb interaction on full counting statistics of electronic transport through single-molecule magnet

    Energy Technology Data Exchange (ETDEWEB)

    Xue Haibin, E-mail: xhb98326110@163.co [Institute of Theoretical Physics, Shanxi University, Taiyuan, Shanxi 030006 (China); Nie, Y.-H., E-mail: nieyh@sxu.edu.c [Institute of Theoretical Physics, Shanxi University, Taiyuan, Shanxi 030006 (China); Li, Z.-J.; Liang, J.-Q. [Institute of Theoretical Physics, Shanxi University, Taiyuan, Shanxi 030006 (China)

    2011-01-17

    We study the full counting statistics (FCS) in a single-molecule magnet (SMM) with finite Coulomb interaction U. For finite U the FCS, differing from U{yields}{infinity}, shows a symmetric gate-voltage-dependence when the coupling strengths with two electrodes are interchanged, which can be observed experimentally just by reversing the bias-voltage. Moreover, we find that the effect of finite U on shot noise depends on the internal level structure of the SMM and the coupling asymmetry of the SMM with two electrodes as well. When the coupling of the SMM with the incident-electrode is stronger than that with the outgoing-electrode, the super-Poissonian shot noise in the sequential tunneling regime appears under relatively small gate-voltage and relatively large finite U, and dose not for U{yields}{infinity}; while it occurs at relatively large gate-voltage for the opposite coupling case. The formation mechanism of super-Poissonian shot noise can be qualitatively attributed to the competition between fast and slow transport channels.

  8. Effect of finite Coulomb interaction on full counting statistics of electronic transport through single-molecule magnet

    International Nuclear Information System (INIS)

    Xue Haibin; Nie, Y.-H.; Li, Z.-J.; Liang, J.-Q.

    2011-01-01

    We study the full counting statistics (FCS) in a single-molecule magnet (SMM) with finite Coulomb interaction U. For finite U the FCS, differing from U→∞, shows a symmetric gate-voltage-dependence when the coupling strengths with two electrodes are interchanged, which can be observed experimentally just by reversing the bias-voltage. Moreover, we find that the effect of finite U on shot noise depends on the internal level structure of the SMM and the coupling asymmetry of the SMM with two electrodes as well. When the coupling of the SMM with the incident-electrode is stronger than that with the outgoing-electrode, the super-Poissonian shot noise in the sequential tunneling regime appears under relatively small gate-voltage and relatively large finite U, and dose not for U→∞; while it occurs at relatively large gate-voltage for the opposite coupling case. The formation mechanism of super-Poissonian shot noise can be qualitatively attributed to the competition between fast and slow transport channels.

  9. Comparing FRACHEM and TOUGHREACT for reactive transport modelingof brine-rock interactions in enhanced geothermal systems (EGS)

    Energy Technology Data Exchange (ETDEWEB)

    Andre, L.; Spycher, N.; Xu, T.; Pruess, K.; Vuataz, F.-D.

    2005-11-15

    Coupled modelling of fluid flow and reactive transport ingeothermal systems is challenging because of reservoir conditions such ashigh temperatures, elevated pressures and sometimes high salinities ofthe formation fluids. Thermal hydrological-chemical (THC) codes, such asFRACHEM and TOUGHREACT, have been developed to evaluate the long-termhydrothermal and chemical evolution of exploited reservoirs. In thisstudy, the two codes were applied to model the same geothermal reservoir,to forecast reservoir evolution using respective thermodynamic andkinetic input data. A recent (unreleased) TOUGHREACT version allows theuse of either an extended Debye-Hu?ckel or Pitzer activity model forcalculating activity coefficients, while FRACHEM was designed to use thePitzer formalism. Comparison of models results indicate that differencesin thermodynamic equilibrium constants, activity coefficients andkinetics models can result in significant differences in predictedmineral precipitation behaviour and reservoir-porosity evolution.Differences in the calculation schemes typically produce less differencein model outputs than differences in input thermodynamic and kineticdata, with model results being particularly sensitive to differences inion-interaction parameters for highsalinity systems.

  10. Air-Sea Interaction

    Science.gov (United States)

    Csanady, G. T.

    2001-03-01

    In recent years air-sea interaction has emerged as a subject in its own right, encompassing small-scale and large-scale processes in both air and sea. Air-Sea Interaction: Laws and Mechanisms is a comprehensive account of how the atmosphere and the ocean interact to control the global climate, what physical laws govern this interaction, and its prominent mechanisms. The topics covered range from evaporation in the oceans, to hurricanes, and on to poleward heat transport by the oceans. By developing the subject from basic physical (thermodynamic) principles, the book is accessible to graduate students and research scientists in meteorology, oceanography, and environmental engineering. It will also be of interest to the broader physics community involved in the treatment of transfer laws, and thermodynamics of the atmosphere and ocean.

  11. Transport Coefficients for the NASA Lewis Chemical Equilibrium Program

    Science.gov (United States)

    Svehla, Roger A.

    1995-01-01

    The new transport property data that will be used in the NASA Lewis Research Center's Chemical Equilibrium and Applications Program (CEA) is presented. It complements a previous publication that documented the thermodynamic and transport property data then in use. Sources of the data and a brief description of the method by which the data were obtained are given. Coefficients to calculate the viscosity, thermal conductivity, and binary interactions are given for either one, or usually, two temperature intervals, typically 300 to 1000 K and 1000 to 5000 K. The form of the transport equation is the same as used previously. The number of species was reduced from the previous database. Many species for which the data were estimated were eliminated from the database. Some ionneutral interactions were added.

  12. Intergovermental Cooperation Initiative on Sustainable Transportation Management in Jabodetabek

    Directory of Open Access Journals (Sweden)

    Hidayat Chusnul Chotimah

    2016-05-01

    Full Text Available The main issues in Jabodetabek concerning the management of transportation are related to the increased use of private vehicles and the decreased use of public transportation, overcrowding daily traffic in Jabodetabek, the high congestion followed by insecurity in traffic, environmental pollution, uncontrolled growth of and underdeveloped infrastructure, and irregularities in land use. To overcome these problems, sustainable transportation management becomes very important in which the government should be able to cope with environmental, economic and social factors under the decision making related to transportation in Jabodetabek. Therefore, through interactive planning, this study will examine intergovernmental cooperation initiatives on sustainable transportation management in Jabodetabek. This study uses qualitative and descriptive method through literature study and existing statistics as the resources to apply the interactive planning approach. The result shows that there are found a number of problems and gaps in the management of transportation in Jabodetabek that needs to be reduced because it has the same scope of other gaps. From these problems can be made further action programs and policies in accordance with the resources owned, and then, the design of implementation made and controlled whether in accordance with the purpose or not. Thus, sustainable transportation management in the Jabodetabek needs to be done jointly in an institutional or policyframework involving governments Jabodetabekpunjur, BKSP Jabodetabekpunjur, and the private sector.

  13. Key role of asymmetric interactions in low-dimensional heat transport

    International Nuclear Information System (INIS)

    Chen, Shunda; Zhang, Yong; Wang, Jiao; Zhao, Hong

    2016-01-01

    We study the heat current autocorrelation function (HCAF) in one-dimensional, momentum-conserving lattices. In particular, we explore if there is any link between the decaying characteristics of the HCAF and asymmetric interparticle interactions. The Lennard-Jones model is investigated intensively in view of its significance to applications. It is found that, in the time range accessible to numerical simulations, the HCAF decays faster than power-law manners, and in some cases it decays even exponentially. Following the Green–Kubo formula, fast decay of the HCAF implies convergence of the heat conductivity, which is also corroborated by simulations. In addition, with a comparison to the Fermi–Pasta–Ulam-β model of symmetric interactions, the HCAF of the Fermi–Pasta–Ulam-α–β model of asymmetric interactions is also investigated. The results of all these studies lead to that, in certain ranges of parameters, fast decaying of the HCAF can be observed and correlated to the asymmetry degree of interactions. (paper: classical statistical mechanics, equilibrium and non-equilibrium)

  14. Aluminum-Activated Malate Transporters Can Facilitate GABA Transport.

    Science.gov (United States)

    Ramesh, Sunita A; Kamran, Muhammad; Sullivan, Wendy; Chirkova, Larissa; Okamoto, Mamoru; Degryse, Fien; McLaughlin, Michael; Gilliham, Matthew; Tyerman, Stephen D

    2018-05-01

    Plant aluminum-activated malate transporters (ALMTs) are currently classified as anion channels; they are also known to be regulated by diverse signals, leading to a range of physiological responses. Gamma-aminobutyric acid (GABA) regulation of anion flux through ALMT proteins requires a specific amino acid motif in ALMTs that shares similarity with a GABA binding site in mammalian GABA A receptors. Here, we explore why TaALMT1 activation leads to a negative correlation between malate efflux and endogenous GABA concentrations ([GABA] i ) in both wheat ( Triticum aestivum ) root tips and in heterologous expression systems. We show that TaALMT1 activation reduces [GABA] i because TaALMT1 facilitates GABA efflux but GABA does not complex Al 3+ TaALMT1 also leads to GABA transport into cells, demonstrated by a yeast complementation assay and via 14 C-GABA uptake into TaALMT1 -expressing Xenopus laevis oocytes; this was found to be a general feature of all ALMTs we examined. Mutation of the GABA motif (TaALMT1 F213C ) prevented both GABA influx and efflux, and resulted in no correlation between malate efflux and [GABA] i We conclude that ALMTs are likely to act as both GABA and anion transporters in planta. GABA and malate appear to interact with ALMTs in a complex manner to regulate each other's transport, suggestive of a role for ALMTs in communicating metabolic status. © 2018 American Society of Plant Biologists. All rights reserved.

  15. Source to sink transport and regulation by environmental factors

    Directory of Open Access Journals (Sweden)

    Remi eLemoine

    2013-07-01

    Full Text Available Source-to-sink transport of sugar is one of the major determinants of plant growth and relies on the efficient and controlled distribution of sucrose (and some other sugars such as raffinose and polyols across plant organs through the phloem. However, sugar transport through the phloem can be affected by many environmental factors that alter source/sink relationships. In this paper, we summarize current knowledge about the phloem transport mechanisms and review the effects of several abiotic (water and salt stress, mineral deficiency, CO2, light, temperature, air and soil pollutants and biotic (mutualistic and pathogenic microbes, viruses, aphids and parasitic plants factors. Concerning abiotic constraints, alteration of the distribution of sugar among sinks is often reported, with some sinks as roots favoured in case of mineral deficiency. Many of these constraints impair the transport function of the phloem but the exact mechanisms are far from being completely known. Phloem integrity can be disrupted (e.g. by callose deposition and under certain conditions, phloem transport is affected, earlier than photosynthesis. Photosynthesis inhibition could result from the increase in sugar concentration due to phloem transport decrease. Biotic interactions (aphids, fungi, viruses… also affect crop plant productivity. Recent breakthroughs have identified some of the sugar transporters involved in these interactions on the host and pathogen sides. The different data are discussed in relation to the phloem transport pathways. When possible, the link with current knowledge on the pathways at the molecular level will be highlighted.

  16. Chaperone turns gatekeeper: PCBP2 and DMT1 form an iron-transport pipeline.

    Science.gov (United States)

    Lane, Darius J R; Richardson, Des R

    2014-08-15

    How is cellular iron (Fe) uptake and efflux regulated in mammalian cells? In this issue of the Biochemical Journal, Yanatori et al. report for the first time that a member of the emerging PCBP [poly(rC)-binding protein] Fe-chaperone family, PCBP2, physically interacts with the major Fe importer DMT1 (divalent metal transporter 1) and the Fe exporter FPN1 (ferroportin 1). In both cases, the interaction of the Fe transporter with PCBP2 is Fe-dependent. Interestingly, another PCBP Fe-chaperone, PCBP1, does not appear to bind to DMT1. Strikingly, the PCBP2-DMT1 interaction is required for DMT1-dependent cellular Fe uptake, suggesting that, in addition to functioning as an intracellular Fe chaperone, PCBP2 may be a molecular 'gate- keeper' for transmembrane Fe transport. These new data hint at the possibility that PCBP2 may be a component of a yet-to-be-described Fe-transport metabolon that engages in Fe channelling to and from Fe transporters and intracellular sites.

  17. Functional interaction between bicarbonate transporters and carbonic anhydrase modulates lactate uptake into mouse cardiomyocytes.

    Science.gov (United States)

    Peetz, Jan; Barros, L Felipe; San Martín, Alejandro; Becker, Holger M

    2015-07-01

    Blood-derived lactate is a precious energy substrate for the heart muscle. Lactate is transported into cardiomyocytes via monocarboxylate transporters (MCTs) together with H(+), which couples lactate uptake to cellular pH regulation. In this study, we have investigated how the interplay between different acid/base transporters and carbonic anhydrases (CA), which catalyze the reversible hydration of CO2, modulates the uptake of lactate into isolated mouse cardiomyocytes. Lactate transport was estimated both as lactate-induced acidification and as changes in intracellular lactate levels measured with a newly developed Förster resonance energy transfer (FRET) nanosensor. Recordings of intracellular pH showed an increase in the rate of lactate-induced acidification when CA was inhibited by 6-ethoxy-2-benzothiazolesulfonamide (EZA), while direct measurements of lactate flux demonstrated a decrease in MCT transport activity, when CA was inhibited. The data indicate that catalytic activity of extracellular CA increases lactate uptake and counteracts intracellular lactate-induced acidification. We propose a hypothetical model, in which HCO3 (-), formed from cell-derived CO2 at the outer surface of the cardiomyocyte plasma membrane by membrane-anchored, extracellular CA, is transported into the cell via Na(+)/HCO3 (-) cotransport to counteract intracellular acidification, while the remaining H(+) stabilizes extracellular pH at the surface of the plasma membrane during MCT activity to enhance lactate influx into cardiomyocytes.

  18. Nonequilibrium thermodynamics of interacting tunneling transport: variational grand potential, density functional formulation and nature of steady-state forces

    International Nuclear Information System (INIS)

    Hyldgaard, P

    2012-01-01

    The standard formulation of tunneling transport rests on an open-boundary modeling. There, conserving approximations to nonequilibrium Green function or quantum statistical mechanics provide consistent but computational costly approaches; alternatively, the use of density-dependent ballistic-transport calculations (e.g., Lang 1995 Phys. Rev. B 52 5335), here denoted ‘DBT’, provides computationally efficient (approximate) atomistic characterizations of the electron behavior but has until now lacked a formal justification. This paper presents an exact, variational nonequilibrium thermodynamic theory for fully interacting tunneling and provides a rigorous foundation for frozen-nuclei DBT calculations as a lowest-order approximation to an exact nonequilibrium thermodynamic density functional evaluation. The theory starts from the complete electron nonequilibrium quantum statistical mechanics and I identify the operator for the nonequilibrium Gibbs free energy which, generally, must be treated as an implicit solution of the fully interacting many-body dynamics. I demonstrate a minimal property of a functional for the nonequilibrium thermodynamic grand potential which thus uniquely identifies the solution as the exact nonequilibrium density matrix. I also show that the uniqueness-of-density proof from a closely related Lippmann-Schwinger collision density functional theory (Hyldgaard 2008 Phys. Rev. B 78 165109) makes it possible to express the variational nonequilibrium thermodynamic description as a single-particle formulation based on universal electron-density functionals; the full nonequilibrium single-particle formulation improves the DBT method, for example, by a more refined account of Gibbs free energy effects. I illustrate a formal evaluation of the zero-temperature thermodynamic grand potential value which I find is closely related to the variation in the scattering phase shifts and hence to Friedel density oscillations. This paper also discusses the

  19. The coat protein of Alternanthera mosaic virus is the elicitor of a temperature-sensitive systemic necrosis in Nicotiana benthamiana, and interacts with a host boron transporter protein

    International Nuclear Information System (INIS)

    Lim, Hyoun-Sub; Nam, Jiryun; Seo, Eun-Young; Nam, Moon; Vaira, Anna Maria; Bae, Hanhong; Jang, Chan-Yong; Lee, Cheol Ho; Kim, Hong Gi; Roh, Mark; Hammond, John

    2014-01-01

    Different isolates of Alternanthera mosaic virus (AltMV; Potexvirus), including four infectious clones derived from AltMV-SP, induce distinct systemic symptoms in Nicotiana benthamiana. Virus accumulation was enhanced at 15 °C compared to 25 °C; severe clone AltMV 3-7 induced systemic necrosis (SN) and plant death at 15 °C. No interaction with potexvirus resistance gene Rx was detected, although SN was ablated by silencing of SGT1, as for other cases of potexvirus-induced necrosis. Substitution of AltMV 3-7 coat protein (CP SP ) with that from AltMV-Po (CP Po ) eliminated SN at 15 °C, and ameliorated symptoms in Alternanthera dentata and soybean. Substitution of only two residues from CP Po [either MN(13,14)ID or LA(76,77)IS] efficiently ablated SN in N. benthamiana. CP SP but not CP Po interacted with Arabidopsis boron transporter protein AtBOR1 by yeast two-hybrid assay; N. benthamiana homolog NbBOR1 interacted more strongly with CP SP than CP Po in bimolecular fluorescence complementation, and may affect recognition of CP as an elicitor of SN. - Highlights: • Alternanthera mosaic virus CP is an elicitor of systemic necrosis in N. benthamiana. • Virus-induced systemic necrosis is enhanced at 15 °C compared to 25 °C. • Induction of systemic necrosis is dependent on as few as two CP amino acid residues. • These residues are at subunit interfaces within the same turn of the virion helix. • Inducer/non-inducer CPs interact differentially with a boron transporter protein

  20. Hepatitis C Virus Proteins Interact with the Endosomal Sorting Complex Required for Transport (ESCRT Machinery via Ubiquitination To Facilitate Viral Envelopment

    Directory of Open Access Journals (Sweden)

    Rina Barouch-Bentov

    2016-11-01

    Full Text Available Enveloped viruses commonly utilize late-domain motifs, sometimes cooperatively with ubiquitin, to hijack the endosomal sorting complex required for transport (ESCRT machinery for budding at the plasma membrane. However, the mechanisms underlying budding of viruses lacking defined late-domain motifs and budding into intracellular compartments are poorly characterized. Here, we map a network of hepatitis C virus (HCV protein interactions with the ESCRT machinery using a mammalian-cell-based protein interaction screen and reveal nine novel interactions. We identify HRS (hepatocyte growth factor-regulated tyrosine kinase substrate, an ESCRT-0 complex component, as an important entry point for HCV into the ESCRT pathway and validate its interactions with the HCV nonstructural (NS proteins NS2 and NS5A in HCV-infected cells. Infectivity assays indicate that HRS is an important factor for efficient HCV assembly. Specifically, by integrating capsid oligomerization assays, biophysical analysis of intracellular viral particles by continuous gradient centrifugations, proteolytic digestion protection, and RNase digestion protection assays, we show that HCV co-opts HRS to mediate a late assembly step, namely, envelopment. In the absence of defined late-domain motifs, K63-linked polyubiquitinated lysine residues in the HCV NS2 protein bind the HRS ubiquitin-interacting motif to facilitate assembly. Finally, ESCRT-III and VPS/VTA1 components are also recruited by HCV proteins to mediate assembly. These data uncover involvement of ESCRT proteins in intracellular budding of a virus lacking defined late-domain motifs and a novel mechanism by which HCV gains entry into the ESCRT network, with potential implications for other viruses.

  1. Neurosteroid Transport in the Brain: Role of ABC and SLC Transporters

    Directory of Open Access Journals (Sweden)

    Markus Grube

    2018-04-01

    Full Text Available Neurosteroids, comprising pregnane, androstane, and sulfated steroids can alter neuronal excitability through interaction with ligand-gated ion channels and other receptors and have therefore a therapeutic potential in several brain disorders. They can be formed in brain cells or are synthesized by an endocrine gland and reach the brain by penetrating the blood–brain barrier (BBB. Especially sulfated steroids such as pregnenolone sulfate (PregS and dehydroepiandrosterone sulfate (DHEAS depend on transporter proteins to cross membranes. In this review, we discuss the involvement of ATP-binding cassette (ABC- and solute carrier (SLC-type membrane proteins in the transport of these compounds at the BBB and in the choroid plexus (CP, but also in the secretion from neurons and glial cells. Among the ABC transporters, especially BCRP (ABCG2 and several MRP/ABCC subfamily members (MRP1, MRP4, MRP8 are expressed in the brain and known to efflux conjugated steroids. Furthermore, several SLC transporters have been shown to mediate cellular uptake of steroid sulfates. These include members of the OATP/SLCO subfamily, namely OATP1A2 and OATP2B1, as well as OAT3 (SLC22A3, which have been reported to be expressed at the BBB, in the CP and in part in neurons. Furthermore, a role of the organic solute transporter OSTα-OSTβ (SLC51A/B in brain DHEAS/PregS homeostasis has been proposed. This transporter was reported to be localized especially in steroidogenic cells of the cerebellum and hippocampus. To date, the impact of transporters on neurosteroid homeostasis is still poorly understood. Further insights are desirable also with regard to the therapeutic potential of these compounds.

  2. Efficiency, selectivity, and robustness of nucleocytoplasmic transport.

    Directory of Open Access Journals (Sweden)

    Anton Zilman

    2007-07-01

    Full Text Available All materials enter or exit the cell nucleus through nuclear pore complexes (NPCs, efficient transport devices that combine high selectivity and throughput. NPC-associated proteins containing phenylalanine-glycine repeats (FG nups have large, flexible, unstructured proteinaceous regions, and line the NPC. A central feature of NPC-mediated transport is the binding of cargo-carrying soluble transport factors to the unstructured regions of FG nups. Here, we model the dynamics of nucleocytoplasmic transport as diffusion in an effective potential resulting from the interaction of the transport factors with the flexible FG nups, using a minimal number of assumptions consistent with the most well-established structural and functional properties of NPC transport. We discuss how specific binding of transport factors to the FG nups facilitates transport, and how this binding and competition between transport factors and other macromolecules for binding sites and space inside the NPC accounts for the high selectivity of transport. We also account for why transport is relatively insensitive to changes in the number and distribution of FG nups in the NPC, providing an explanation for recent experiments where up to half the total mass of the FG nups has been deleted without abolishing transport. Our results suggest strategies for the creation of artificial nanomolecular sorting devices.

  3. Influence of multidrug resistance and drug transport proteins on chemotherapy drug metabolism.

    Science.gov (United States)

    Joyce, Helena; McCann, Andrew; Clynes, Martin; Larkin, Annemarie

    2015-05-01

    Chemotherapy involving the use of anticancer drugs remains an important strategy in the overall management of patients with metastatic cancer. Acquisition of multidrug resistance remains a major impediment to successful chemotherapy. Drug transporters in cell membranes and intracellular drug metabolizing enzymes contribute to the resistance phenotype and determine the pharmacokinetics of anticancer drugs in the body. ATP-binding cassette (ABC) transporters mediate the transport of endogenous metabolites and xenobiotics including cytotoxic drugs out of cells. Solute carrier (SLC) transporters mediate the influx of cytotoxic drugs into cells. This review focuses on the substrate interaction of these transporters, on their biology and what role they play together with drug metabolizing enzymes in eliminating therapeutic drugs from cells. The majority of anticancer drugs are substrates for the ABC transporter and SLC transporter families. Together, these proteins have the ability to control the influx and the efflux of structurally unrelated chemotherapeutic drugs, thereby modulating the intracellular drug concentration. These interactions have important clinical implications for chemotherapy because ultimately they determine therapeutic efficacy, disease progression/relapse and the success or failure of patient treatment.

  4. Statistical analysis of anomalous transport in resistive interchange turbulence

    International Nuclear Information System (INIS)

    Sugama, Hideo; Wakatani, Masahiro.

    1992-01-01

    A new anomalous transport model for resistive interchange turbulence is derived from statistical analysis applying two-scale direct-interaction approximation to resistive magnetohydrodynamic equations with a gravity term. Our model is similar to the K-ε model for eddy viscosity of turbulent shear flows in that anomalous transport coefficients are expressed in terms of by the turbulent kinetic energy K and its dissipation rate ε while K and ε are determined by transport equations. This anomalous transport model can describe some nonlocal effects such as those from boundary conditions which cannot be treated by conventional models based on the transport coefficients represented by locally determined plasma parameters. (author)

  5. Transport barriers in bootstrap-driven tokamaks

    Science.gov (United States)

    Staebler, G. M.; Garofalo, A. M.; Pan, C.; McClenaghan, J.; Van Zeeland, M. A.; Lao, L. L.

    2018-05-01

    Experiments have demonstrated improved energy confinement due to the spontaneous formation of an internal transport barrier in high bootstrap fraction discharges. Gyrokinetic analysis, and quasilinear predictive modeling, demonstrates that the observed transport barrier is caused by the suppression of turbulence primarily from the large Shafranov shift. It is shown that the Shafranov shift can produce a bifurcation to improved confinement in regions of positive magnetic shear or a continuous reduction in transport for weak or negative magnetic shear. Operation at high safety factor lowers the pressure gradient threshold for the Shafranov shift-driven barrier formation. Two self-organized states of the internal and edge transport barrier are observed. It is shown that these two states are controlled by the interaction of the bootstrap current with magnetic shear, and the kinetic ballooning mode instability boundary. Election scale energy transport is predicted to be dominant in the inner 60% of the profile. Evidence is presented that energetic particle-driven instabilities could be playing a role in the thermal energy transport in this region.

  6. KBS-3H. Reactive transport modelling of iron-bentonite interactions, an update for the Olkiluoto case

    International Nuclear Information System (INIS)

    Birgersson, M.; Wersin, P.

    2014-03-01

    According to the KBS-3H concept, each copper canister containing spent nuclear fuel will be surrounded by a bentonite buffer and a perforated cylinder. The originally planned material for the perforated steel cylinder shell has been carbon steel. After emplacement, the steel material will corrode anaerobically in contact with water and generate hydrogen, iron species and hydroxyl ions. Iron corrosion products will be formed at the steel surface, but in addition, the released species may interact with the clay and lead to undesirable effects, such as montmorillonite transformation and cementation. The impact of corrosion and iron-bentonite interactions has been assessed for Olkiluoto-specific conditions by reactive transport modelling using the CrunchFlow code. The main focus of this modelling exercise was to update the previous modelling study of Wersin et al. (2007). by accounting for new thermodynamic data on clays and uncertainties in precipitation rates of iron reaction products. The modelling strategy was first to select appropriate thermodynamic and kinetic mineral by review of current data, in particular of the THERMODDEM database, and by chemical equilibrium modelling. Second, a 1D reactive transport model which includes a corroding iron source from which solutes can diffuse into the buffer and interact with the clay and accessory minerals was set up in a similar way as that applied in Wersin et al. (2007). A number of test cases were defined, including a Base Case and various less likely as well as bounding cases. The modelling results largely confirmed previous findings in that the zone of alteration was predicted to remain spatially limited for very long times. However, they highlighted that under unfavourable conditions during the initial corrosion phase (before complete corrosion of the shell), pronounced increase in pH might occur, which would lead to enhanced dissolution of the montmorillonite clay. Factors favouring pH increase were found to be slow

  7. KBS-3H. Reactive transport modelling of iron-bentonite interactions, an update for the Olkiluoto case

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, M. [Clay Technology AB, Lund (Sweden); Wersin, P. [Bern Univ. (Switzerland)

    2014-03-15

    According to the KBS-3H concept, each copper canister containing spent nuclear fuel will be surrounded by a bentonite buffer and a perforated cylinder. The originally planned material for the perforated steel cylinder shell has been carbon steel. After emplacement, the steel material will corrode anaerobically in contact with water and generate hydrogen, iron species and hydroxyl ions. Iron corrosion products will be formed at the steel surface, but in addition, the released species may interact with the clay and lead to undesirable effects, such as montmorillonite transformation and cementation. The impact of corrosion and iron-bentonite interactions has been assessed for Olkiluoto-specific conditions by reactive transport modelling using the CrunchFlow code. The main focus of this modelling exercise was to update the previous modelling study of Wersin et al. (2007). by accounting for new thermodynamic data on clays and uncertainties in precipitation rates of iron reaction products. The modelling strategy was first to select appropriate thermodynamic and kinetic mineral by review of current data, in particular of the THERMODDEM database, and by chemical equilibrium modelling. Second, a 1D reactive transport model which includes a corroding iron source from which solutes can diffuse into the buffer and interact with the clay and accessory minerals was set up in a similar way as that applied in Wersin et al. (2007). A number of test cases were defined, including a Base Case and various less likely as well as bounding cases. The modelling results largely confirmed previous findings in that the zone of alteration was predicted to remain spatially limited for very long times. However, they highlighted that under unfavourable conditions during the initial corrosion phase (before complete corrosion of the shell), pronounced increase in pH might occur, which would lead to enhanced dissolution of the montmorillonite clay. Factors favouring pH increase were found to be slow

  8. Subsurface transport program: Research summary

    International Nuclear Information System (INIS)

    1987-01-01

    DOE's research program in subsurface transport is designed to provide a base of fundamental scientific information so that the geochemical, hydrological, and biological mechanisms that contribute to the transport and long term fate of energy related contaminants in subsurface ecosystems can be understood. Understanding the physical and chemical mechanisms that control the transport of single and co-contaminants is the underlying concern of the program. Particular attention is given to interdisciplinary research and to geosphere-biosphere interactions. The scientific results of the program will contribute to resolving Departmental questions related to the disposal of energy-producing and defense wastes. The background papers prepared in support of this document contain additional information on the relevance of the research in the long term to energy-producing technologies. Detailed scientific plans and other research documents are available for high priority research areas, for example, in subsurface transport of organic chemicals and mixtures and in the microbiology of deep aquifers. 5 figs., 1 tab

  9. Psychological distress following marital separation interacts with a polymorphism in the serotonin transporter gene to predict cardiac vagal control in the laboratory.

    Science.gov (United States)

    Hasselmo, Karen; Sbarra, David A; O'Connor, Mary-Frances; Moreno, Francisco A

    2015-06-01

    Marital separation is linked to negative mental and physical health; however, the strength of this link may vary across people. This study examined changes in respiratory sinus arrhythmia (RSA), used to assess cardiac vagal control, in recently separated adults (N = 79; M time since separation = 3.5 months). When reflecting on the separation, self-reported psychological distress following the separation interacted with a polymorphism in the serotonin transporter gene (5-HTTLPR) and a relevant single nucleotide polymorphism (SNP), rs25531, to predict RSA. Among people reporting emotional difficulties after the separation, those who were homozygous for the short allele had lower RSA levels while reflecting on their relationship than other genotypes. The findings, although limited by the relatively small sample size, are discussed in terms of how higher-sensitivity genotypes may interact with psychological responses to stress to alter physiology. © 2015 Society for Psychophysiological Research.

  10. Imidazole-4-acetic acid, a new lead structure for interaction with the taurine transporter in outer blood-retinal barrier cells.

    Science.gov (United States)

    Valembois, Sophie; Krall, Jacob; Frølund, Bente; Steffansen, Bente

    2017-05-30

    Retinal diseases leading to impaired vision and ultimately blindness are mainly characterized by ischemic and hypoxic stress. Targeting the retinal ρ-containing γ-aminobutyric acid type A receptors (ρ GABA A Rs) and thereby decreasing the retinal neuronal activity has been proposed as a novel therapeutic approach. The taurine transporter (TAUT) plays a key role in the retinal transport of GABA and has been previously suggested to display a higher functional activity in the retina compared to the brain. TAUT would therefore stand as a suitable target for the selective delivery of ρ GABA A R ligands into the retina. Consequently, an in vitro model of TAUT at the outer blood-retinal barrier (BRB) was developed and characterized using the ARPE-19 cell line. Furthermore, the structural requirements of GABA A R ligands for interacting with TAUT at the BRB were investigated for a series of standard GABA A R ligands by testing their ability to inhibit the TAUT-mediated influx of taurine in ARPE-19 cells. Results showed that taurine influx was seven-fold higher when the ARPE-19 cells were cultured under hyperosmotic conditions and was demonstrated to display saturable kinetics (K m =27.7±2.2μM and J max =24.2±0.6pmol/cm 2 ·min). Furthermore, the taurine influx was significantly inhibited in a concentration-dependent manner by GABA and imidazole-4-acetic acid (IAA), which is a naturally occurring metabolite of histamine. These compounds display similar K i values of 644.2μM and 658.6μM, respectively. Moreover, IAA demonstrated higher inhibitory properties than the other tested GABA analogs: 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), 4,5,6,7-tetrahydropyrazolo[5,4-c]pyridin-3-ol (Aza-THIP), muscimol, and thiomuscimol. These studies demonstrated that IAA interacts with TAUT, which makes IAA a new lead structure in the development of new compounds, which are not only interacting with TAUT but also potent ρ GABA A R ligands. Copyright © 2017 Elsevier B

  11. Thermal Transport in Phosphorene.

    Science.gov (United States)

    Qin, Guangzhao; Hu, Ming

    2018-03-01

    Phosphorene, a novel elemental 2D semiconductor, possesses fascinating chemical and physical properties which are distinctively different from other 2D materials. The rapidly growing applications of phosphorene in nano/optoelectronics and thermoelectrics call for comprehensive studies of thermal transport properties. In this Review, based on the theoretical and experimental progresses, the thermal transport properties of single-layer phosphorene, multilayer phosphorene (nanofilms), and bulk black phosphorus are summarized to give a general view of the overall thermal conductivity trend from single-layer to bulk form. The mechanism underlying the discrepancy in the reported thermal conductivity of phosphorene is discussed by reviewing the effect of different functionals and cutoff distances on the thermal transport evaluations. This Review then provides fundamental insight into the thermal transport in phosphorene by reviewing the role of resonant bonding in driving giant phonon anharmonicity and long-range interactions. In addition, the extrinsic thermal conductivity of phosphorene is reviewed by discussing the effects of strain and substrate, together with phosphorene based heterostructures and nanoribbons. This Review summarizes the progress of thermal transport in phosphorene from both theoretical calculations and experimental measurements, which would be of significance to the design and development of efficient phosphorene based nanoelectronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Radiation interaction with substance and simulation of the nuclear geophysical problems

    International Nuclear Information System (INIS)

    Pshenichnyj, G.A.

    1982-01-01

    Main processes of interaction of various types of nuclear radiation (NR) with substance, NR transport theory and physical- mathematical simulation of basic problems of nuclear geophysics (NG) are considered. General classification of NG methods according to the type of the detected radiation with a more detailed division according to the physical essence of the interaction process employed is given. Direct NG problems are related to the study of space- energy radiation distribution in substance under certain cross sections of elementary interaction processes, substance properties and specified geometric conditions. The theoretical solution of the direct problems is based on using mathematical models of radiation transport in specified media. The NG inverse problems consist in determining element composition and other medium properties by data of integral or spectral characteristics of NR fields measurements. The NR in the course of its transport in substance can experience dozens of elementary interaction processes, the predominance of this or that process depending on NR energy, medium properties and geometric measurement conditions. This explains a wide NG method diversity. The Monte Carlo method application in the NR transport theory and various methods of decreasing calculations labour input are considered [ru

  13. Hydrodynamic approach to electronic transport in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Narozhny, Boris N. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Gornyi, Igor V. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Ioffe Physical Technical Institute, St. Petersburg (Russian Federation); Mirlin, Alexander D. [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Schmalian, Joerg [Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute for Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2017-11-15

    The last few years have seen an explosion of interest in hydrodynamic effects in interacting electron systems in ultra-pure materials. In this paper we briefly review the recent advances, both theoretical and experimental, in the hydrodynamic approach to electronic transport in graphene, focusing on viscous phenomena, Coulomb drag, non-local transport measurements, and possibilities for observing nonlinear effects. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Tubular transport and metabolism of cimetidine in chicken kidneys

    International Nuclear Information System (INIS)

    Rennick, B.; Ziemniak, J.; Smith, I.; Taylor, M.; Acara, M.

    1984-01-01

    Renal tubular transport and renal metabolism of [ 14 C]cimetidine (CIM) were investigated by unilateral infusion into the renal portal circulation in chickens (Sperber technique). [ 14 C]CIM was actively transported at a rate 88% that of simultaneously infused p-aminohippuric acid, and its transport was saturable. The following organic cations competitively inhibited the tubular transport of [ 14 C]CIM with decreasing potency: CIM, ranitidine, thiamine, procainamide, guanidine and choline. CIM inhibited the transport of [ 14 C]thiamine, [ 14 C]amiloride and [ 14 C]tetraethylammonium. During CIM infusion, two renal metabolites, CIM sulfoxide and hydroxymethylcimetidine, were found in urine. When CIM sulfoxide was infused, its transport efficiency was 32% and not saturable. CIM sulfoxide did ot inhibit the simultaneous renal tubular transport of p-aminohippuric acid or tetraethylammonium. CIM is transported by the organic cation transport system and the kidney metabolizes CIM. Transport of CIM and other cationic drugs could produce a drug interaction to alter drug excretion

  15. Interactive transport of guanidinylated poly(propylene imine)-based dendrimers through liposomal and cellular membranes.

    Science.gov (United States)

    Tsogas, Ioannis; Sideratou, Zili; Tsiourvas, Dimitris; Theodossiou, Theodossis A; Paleos, Constantinos M

    2007-10-15

    The ability of guanidinylated poly(propylene imine) dendrimers to translocate across lipid bilayers was assessed by employing either a model phosphate-bearing liposomal membrane system or A549 human lung carcinoma cells. Two dendrimer generations, differing in the number of surface guanidinium groups, were employed, while surface acetylation or the use of spacers affected the binding of the guanidinium group to the phosphate moiety and finally the transport efficiency. Following adhesion of dendrimers with liposomes, fusion or transport occurred. Transport through the liposomal bilayer was observed at low guanidinium/phosphate molar ratios, and was enhanced when the bilayer was in the liquid-crystalline phase. For effective transport through the liposomal membrane, an optimum balance between the binding strength and the degree of hydrophobicity of the guanidinylated dendrimer is required. In experiments performed in vitro with cells, efficient penetration and internalization in subcellular organelles and cytosol was observed.

  16. pH modulates transport rates of manganese and cadmium in the green alga Chlamydomonas reinhardtii through non-competitive interactions: Implications for an algal BLM

    International Nuclear Information System (INIS)

    Francois, Laura; Fortin, Claude; Campbell, Peter G.C.

    2007-01-01

    The influence of pH on short-term uptake of manganese and cadmium by the green alga Chlamydomonas reinhardtii was studied to better understand the nature of proton interactions with metal membrane transporters. Manganese and cadmium internalization fluxes (J int ) were measured over a wide range of free metal ion concentrations from 1 x 10 -10 to 4 x 10 -4 M at several pH values (Mn: 5.0, 6.5 and 8.0; Cd: 5.0 and 6.5). For both metals, first-order biological internalization kinetics were observed but the maximum transport flux (J max ) decreased when pH decreased, in contradiction with the Biotic Ligand Model (BLM). This result suggested a non-competitive inhibition of metal uptake by the H + -ion. A Michaelis-Menten type inhibition model considering proton and calcium competition was tested. The metal biotic ligand stability constants and the stability constants for competitive binding of Ca 2+ and H + with the metal transporters were calculated: for manganese, K Mn = 10 4.20 and K Ca = 10 3.71 ; for cadmium, K Cd = 10 4.19 and K Ca = 10 4.76 ; for both metal transport systems, K H was not a significant parameter. Furthermore, metal uptake was not significantly influenced by the pH of the antecedent growth medium, suggesting that increases in metal fluxes as the pH is raised are caused by conformational changes of the surface transport proteins rather than by the synthesis of additional transport sites. Our results demonstrate that the BLM in its present state does not properly describe the true influence of pH on manganese and cadmium uptake by algae and that a non-competitive inhibition component must be integrated

  17. The 3rd Asia–Pacific Transport Working Group (APTWG) Meeting

    International Nuclear Information System (INIS)

    Jhang, Hogun; Diamond, P.H.; Leconte, M.; Kwon, J.M.; Ida, K.; Tamura, N.; Kosuga, Y.

    2014-01-01

    This conference report summarizes the contributions to and discussions at the 3rd Asia–Pacific Transport Working Group (APTWG) meeting held in Jeju-island, Korea, on 21–24 May 2013. The main objective of the meeting is to develop a predictive understanding of transport mechanisms in magnetically confined fusion plasmas. In an effort to accomplish this objective, four technical working groups were organized under the headings: (1) transport barrier formation and confinement enhancement, (2) 3D effects and Magnetohydrodynamic–turbulence interaction, (3) momentum transport and non-locality and (4) particle/impurity transport and energetic particles. (conference report)

  18. Vgi Based Urban Public Transport

    Science.gov (United States)

    Teymurian, F.; Alesheikh, A. A.; Alimohammadi, A.; Sadeghi-Niaraki, A.

    2013-09-01

    Recent advances in information technology have made geographic information system (GIS) a powerful and affordable tool for planning and decision making in various fields such as the public transportation. These technologies such as the social network (e.g. face-book, twitter), new technologies such as ubiquitous, mobile, Web 2.0, geo tagging and RFID can help to create better shapes and forms of the communication and geo-collaboration for public. By using these, user-generated content and spatial information can be easily and quickly produced and shared in a dynamic, interactive, multimedia and distributed environment. The concept of volunteered geographic information (VGI) has been introduced by the transaction from consultation to content interaction. VGI describes any type of content that has a geographic element and has been voluntarily collected. In other words, ordinary users; without a professional training, can participate in generating and using the spatial information. As a result, the gaps between the producers and users of GIS and spatial information, has been considerably reduced. Public transportation is one of the most important elements of the transportation system. Rapid growth of the cities has resulted in high increase of demand for the public transportation which created new challenges. Improvement of the desirability of public transportation can increase its efficiency, reduction of the environmental pollution (such as air and noise pollution), traffic problems, and fuel consumption. Hence, development of an urban public transportation system which is responsive to citizen's need and motivates them to use public transportation system is one of the most important objectives and issues that urban planners and designers are concerned about. One solution to achieve this, goal is to develop public transportation system by assistance from the system users. According to approach, users are considered as the valuable resources, because people who are

  19. Plant viral nanoparticles-based HER2 vaccine: Immune response influenced by differential transport, localization and cellular interactions of particulate carriers.

    Science.gov (United States)

    Shukla, Sourabh; Myers, Jay T; Woods, Sarah E; Gong, Xingjian; Czapar, Anna E; Commandeur, Ulrich; Huang, Alex Y; Levine, Alan D; Steinmetz, Nicole F

    2017-03-01

    Cancer vaccines are designed to elicit an endogenous adaptive immune response that can successfully recognize and eliminate residual or recurring tumors. Such approaches can potentially overcome shortcomings of passive immunotherapies by generating long-lived therapeutic effects and immune memory while limiting systemic toxicities. A critical determinant of vaccine efficacy is efficient transport and delivery of tumor-associated antigens to professional antigen presenting cells (APCs). Plant viral nanoparticles (VNPs) with natural tropism for APCs and a high payload carrying capacity may be particularly effective vaccine carriers. The applicability of VNP platform technologies is governed by stringent structure-function relationships. We compare two distinct VNP platforms: icosahedral cowpea mosaic virus (CPMV) and filamentous potato virus X (PVX). Specifically, we evaluate in vivo capabilities of engineered VNPs delivering human epidermal growth factor receptor 2 (HER2) epitopes for therapy and prophylaxis of HER2 + malignancies. Our results corroborate the structure-function relationship where icosahedral CPMV particles showed significantly enhanced lymph node transport and retention, and greater uptake by/activation of APCs compared to filamentous PVX particles. These enhanced immune cell interactions and transport properties resulted in elevated HER2-specific antibody titers raised by CPMV- vs. PVX-based peptide vaccine. The 'synthetic virology' field is rapidly expanding with numerous platforms undergoing development and preclinical testing; our studies highlight the need for systematic studies to define rules guiding the design and rational choice of platform, in the context of peptide-vaccine display technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. The coat protein of Alternanthera mosaic virus is the elicitor of a temperature-sensitive systemic necrosis in Nicotiana benthamiana, and interacts with a host boron transporter protein

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyoun-Sub, E-mail: hyounlim@cnu.ac.kr [Department of Applied Biology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Nam, Jiryun, E-mail: jilyoon@naver.com [Department of Applied Biology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Seo, Eun-Young, E-mail: sey22@cnu.ac.kr [Department of Applied Biology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Nam, Moon, E-mail: moonlit51@cnu.ac.kr [Department of Applied Biology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Vaira, Anna Maria, E-mail: a.vaira@ivv.cnr.it [Floral and Nursery Plants Research Unit, US National Arboretum, USDA-ARS, 10300 Baltimore Avenue B-010A, Beltsville, MD 20705 (United States); Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, Torino 10135 (Italy); Bae, Hanhong, E-mail: hanhongbae@ynu.ac.kr [School of Biotechnology, Yeungnam University, Geongsan 712-749 (Korea, Republic of); Jang, Chan-Yong, E-mail: sunbispirit@gmail.com [Department of Applied Biology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lee, Cheol Ho, E-mail: chlee1219@hanmail.net [Department of Chemical and Biological Engineering, Seokyoung University, Seoul 136-704 (Korea, Republic of); Kim, Hong Gi, E-mail: hgkim@cnu.ac.kr [Department of Applied Biology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Roh, Mark, E-mail: marksroh@gmail.com [Floral and Nursery Plants Research Unit, US National Arboretum, USDA-ARS, 10300 Baltimore Avenue B-010A, Beltsville, MD 20705 (United States); Laboratory of Floriculture and Plant Physiology, School of Bio-Resource Science, Dankook University, Cheonan, Chungnam 330-714 (Korea, Republic of); Hammond, John, E-mail: john.hammond@ars.usda.gov [Floral and Nursery Plants Research Unit, US National Arboretum, USDA-ARS, 10300 Baltimore Avenue B-010A, Beltsville, MD 20705 (United States)

    2014-03-15

    Different isolates of Alternanthera mosaic virus (AltMV; Potexvirus), including four infectious clones derived from AltMV-SP, induce distinct systemic symptoms in Nicotiana benthamiana. Virus accumulation was enhanced at 15 °C compared to 25 °C; severe clone AltMV 3-7 induced systemic necrosis (SN) and plant death at 15 °C. No interaction with potexvirus resistance gene Rx was detected, although SN was ablated by silencing of SGT1, as for other cases of potexvirus-induced necrosis. Substitution of AltMV 3-7 coat protein (CP{sub SP}) with that from AltMV-Po (CP{sub Po}) eliminated SN at 15 °C, and ameliorated symptoms in Alternanthera dentata and soybean. Substitution of only two residues from CP{sub Po} [either MN(13,14)ID or LA(76,77)IS] efficiently ablated SN in N. benthamiana. CP{sub SP} but not CP{sub Po} interacted with Arabidopsis boron transporter protein AtBOR1 by yeast two-hybrid assay; N. benthamiana homolog NbBOR1 interacted more strongly with CP{sub SP} than CP{sub Po} in bimolecular fluorescence complementation, and may affect recognition of CP as an elicitor of SN. - Highlights: • Alternanthera mosaic virus CP is an elicitor of systemic necrosis in N. benthamiana. • Virus-induced systemic necrosis is enhanced at 15 °C compared to 25 °C. • Induction of systemic necrosis is dependent on as few as two CP amino acid residues. • These residues are at subunit interfaces within the same turn of the virion helix. • Inducer/non-inducer CPs interact differentially with a boron transporter protein.

  1. 1D momentum-conserving systems: the conundrum of anomalous versus normal heat transport

    International Nuclear Information System (INIS)

    Li, Yunyun; Li, Nianbei; Hänggi, Peter; Li, Baowen; Liu, Sha

    2015-01-01

    Transport and the spread of heat in Hamiltonian one dimensional momentum conserving nonlinear systems is commonly thought to proceed anomalously. Notable exceptions, however, do exist of which the coupled rotator model is a prominent case. Therefore, the quest arises to identify the origin of manifest anomalous energy and momentum transport in those low dimensional systems. We develop the theory for both, the statistical densities for momentum- and energy-spread and particularly its momentum-/heat-diffusion behavior, as well as its corresponding momentum/heat transport features. We demonstrate that the second temporal derivative of the mean squared deviation of the momentum spread is proportional to the equilibrium correlation of the total momentum flux. Subtracting the part which corresponds to a ballistic momentum spread relates (via this integrated, subleading momentum flux correlation) to an effective viscosity, or equivalently, to the underlying momentum diffusivity. We next put forward the intriguing hypothesis: normal spread of this so adjusted excess momentum density causes normal energy spread and alike normal heat transport (Fourier Law). Its corollary being that an anomalous, superdiffusive broadening of this adjusted excess momentum density in turn implies an anomalous energy spread and correspondingly anomalous, superdiffusive heat transport. This hypothesis is successfully corroborated within extensive molecular dynamics simulations over large extended time scales. Our numerical validation of the hypothesis involves four distinct archetype classes of nonlinear pair-interaction potentials: (i) a globally bounded pair interaction (the noted coupled rotator model), (ii) unbounded interactions acting at large distances (the coupled rotator model amended with harmonic pair interactions), (iii) the case of a hard point gas with unbounded square-well interactions and (iv) a pair interaction potential being unbounded at short distances while displaying an

  2. 1D momentum-conserving systems: the conundrum of anomalous versus normal heat transport

    Science.gov (United States)

    Li, Yunyun; Liu, Sha; Li, Nianbei; Hänggi, Peter; Li, Baowen

    2015-04-01

    Transport and the spread of heat in Hamiltonian one dimensional momentum conserving nonlinear systems is commonly thought to proceed anomalously. Notable exceptions, however, do exist of which the coupled rotator model is a prominent case. Therefore, the quest arises to identify the origin of manifest anomalous energy and momentum transport in those low dimensional systems. We develop the theory for both, the statistical densities for momentum- and energy-spread and particularly its momentum-/heat-diffusion behavior, as well as its corresponding momentum/heat transport features. We demonstrate that the second temporal derivative of the mean squared deviation of the momentum spread is proportional to the equilibrium correlation of the total momentum flux. Subtracting the part which corresponds to a ballistic momentum spread relates (via this integrated, subleading momentum flux correlation) to an effective viscosity, or equivalently, to the underlying momentum diffusivity. We next put forward the intriguing hypothesis: normal spread of this so adjusted excess momentum density causes normal energy spread and alike normal heat transport (Fourier Law). Its corollary being that an anomalous, superdiffusive broadening of this adjusted excess momentum density in turn implies an anomalous energy spread and correspondingly anomalous, superdiffusive heat transport. This hypothesis is successfully corroborated within extensive molecular dynamics simulations over large extended time scales. Our numerical validation of the hypothesis involves four distinct archetype classes of nonlinear pair-interaction potentials: (i) a globally bounded pair interaction (the noted coupled rotator model), (ii) unbounded interactions acting at large distances (the coupled rotator model amended with harmonic pair interactions), (iii) the case of a hard point gas with unbounded square-well interactions and (iv) a pair interaction potential being unbounded at short distances while displaying an

  3. PLANNING FOR THE FUTURE: A LAND-USE AND TRANSPORT INTERACTION MODEL FOR SWITZERLAND

    OpenAIRE

    Balz R. Bodenmann; Breogan Sanchez; Alexandra Zeiler; Milan Kuliowsky; Peter Furtak; Georgios Sarlas

    2014-01-01

    Spatial and transport planners, authorities, real estate developers, investors, re-locating residents and businesses have different questions related to space and transport. These questions may concern specific land parcels, or cover a much larger area such as a city, a region, or even a whole nation. Amongst others, these questions include: - How will our society respond to influences of global economy and political decisions (e.g. regarding demographics and firmographics)? - Which strategie...

  4. Impact of transporters in oral absorption

    DEFF Research Database (Denmark)

    Gram, Luise Kvisgaard; Rist, Gerda Marie; Steffansen, Bente

    2009-01-01

    A key determinant for oral bioavailability of a drug candidate is the intestinal epithelial permeation of the drug candidate. This intestinal permeation may be affected by interactions on membrane transporters expressed in the intestinal epithelial cells. The purpose of the present study...

  5. Vehicle/Guideway Interaction in Maglev Systems

    Science.gov (United States)

    1992-03-01

    Technology Division Materials and Components in Maglev Systems Technology Division Materials and Components Technology Division byY. Cai, S. S. Chen, and D. M...Transportation Systems Reports (UC-330, Vehicle/Guideway Interaction in Maglev Systems by Y. Cai and S. S. Chen Materials and Components Technology Division D. M...Surface Irregularities ...................................... 32 4 Vehicle/Guideway Interaction in Transrapid Maglev System .................. 34 4.1

  6. Drift-Scale Radionuclide Transport

    International Nuclear Information System (INIS)

    Houseworth, J.

    2004-01-01

    The purpose of this model report is to document the drift scale radionuclide transport model, taking into account the effects of emplacement drifts on flow and transport in the vicinity of the drift, which are not captured in the mountain-scale unsaturated zone (UZ) flow and transport models ''UZ Flow Models and Submodels'' (BSC 2004 [DIRS 169861]), ''Radionuclide Transport Models Under Ambient Conditions'' (BSC 2004 [DIRS 164500]), and ''Particle Tracking Model and Abstraction of Transport Process'' (BSC 2004 [DIRS 170041]). The drift scale radionuclide transport model is intended to be used as an alternative model for comparison with the engineered barrier system (EBS) radionuclide transport model ''EBS Radionuclide Transport Abstraction'' (BSC 2004 [DIRS 169868]). For that purpose, two alternative models have been developed for drift-scale radionuclide transport. One of the alternative models is a dual continuum flow and transport model called the drift shadow model. The effects of variations in the flow field and fracture-matrix interaction in the vicinity of a waste emplacement drift are investigated through sensitivity studies using the drift shadow model (Houseworth et al. 2003 [DIRS 164394]). In this model, the flow is significantly perturbed (reduced) beneath the waste emplacement drifts. However, comparisons of transport in this perturbed flow field with transport in an unperturbed flow field show similar results if the transport is initiated in the rock matrix. This has led to a second alternative model, called the fracture-matrix partitioning model, that focuses on the partitioning of radionuclide transport between the fractures and matrix upon exiting the waste emplacement drift. The fracture-matrix partitioning model computes the partitioning, between fractures and matrix, of diffusive radionuclide transport from the invert (for drifts without seepage) into the rock water. The invert is the structure constructed in a drift to provide the floor of the

  7. What Moves Them? Active Transport among Inhabitants of Dutch Deprived Districts

    Directory of Open Access Journals (Sweden)

    Carla Saris

    2013-01-01

    Full Text Available Background. Active modes of transport like walking and cycling have been shown to be valuable contributions to daily physical activity. The current study investigates associations between personal and neighbourhood environmental characteristics and active transport among inhabitants of Dutch deprived districts. Method. Questionnaires about health, neighbourhoods, and physical activity behaviour were completed by 742 adults. Data was analysed by means of multivariate linear regression analyses. Results. Being younger, female, and migrant and having a normal weight were associated with more walking for active transport. Being younger, male, and native Dutch and having a normal weight were associated with more cycling for active transport. Neighbourhood characteristics were generally not correlated with active transport. Stratified analyses, based on significant person-environment interactions, showed that migrants and women walked more when cars did not exceed maximum speed in nearby streets and that younger people walked more when speed of traffic in nearby streets was perceived as low. Among migrants, more cycling was associated with the perceived attractiveness of the neighbourhood surroundings. Discussion and Conclusion. Results indicated that among inhabitants of Dutch deprived districts, personal characteristics were associated with active transport, whereas neighbourhood environmental characteristics were generally not associated with active transport. Nevertheless, interaction effects showed differences among subgroups that should be considered in intervention development.

  8. Engineering solutions of traffic safety problems of road transport

    Directory of Open Access Journals (Sweden)

    M. Bogdevičius

    2004-02-01

    Full Text Available The authors of this paper focus on the simulation of the motor vehicle movement (taking into consideration motor vehicle dynamics, motor vehicle hydraulic brake system influence on motor vehicle movement, interaction between its wheels with road pavements, road guardrail characteristics, interaction between motor vehicle and road guardrail on a certain road section and propose their specific solution of this problem. The presented results, illustrating the motor vehicle movement trajectories (motor vehicle braking and interaction between motor vehicle and road guardrail at various initial conditions and at various certain pavement surface of the road section under investigation and work of a motor vehicle hydraulic brake system. Taking into consideration the presented general mathematical model and computer aided test results it is possible to investigate various road transport traffic situations as well as to investigate various transport traffic safety problems.

  9. Interaction of an ultra-intense laser pulse with a dense plasma: heating and transport of electrons and ions

    International Nuclear Information System (INIS)

    Toupin, Catherine

    1999-01-01

    This work was aimed at characterizing the acceleration and transport of the plasma electrons and ions during the interaction of an ultra-intense laser pulse with a dense plasma. Our main tool was numerical simulation with kinetic particle-in-cell codes. During the interaction, the target surface electrons are accelerated up to high energies inward the target. The electron acceleration mechanisms are proved to strongly depend on the density profile deformation due to the ion motion. This motion has been studied as well and different acceleration mechanisms have been identified: pushing in of the target surface by the laser ponderomotive pressure, acceleration by an electrostatic shock or by breaking of an ion acoustic wave, acceleration by the space charge force induced by radial expulsion of the electrons out of a channel drilled in a slightly overcritical plasma. The electrons and ions accelerated at the target surface penetrate inward the target and interact with it. The competition between the focussing due to the self-generated magnetic field, driven by the very important electron current, and the scattering induced by collisions has been analyzed. In a homogeneous, hot plasma, the existence of an optimum current for which the propagation length without scattering is maximum, has been demonstrated. The electron drag-back effect of the axial electric field is also proved to be more significant than the friction due to collisions. By penetrating into the target, the accelerated ions can produce neutrons if the target is deuterated. A strong correlation between the ion acceleration mechanisms and the angle and energy distributions of the produced neutrons has been underlined. (author) [fr

  10. The content and features of transport servicing of region economy

    Directory of Open Access Journals (Sweden)

    L. P. Paristova

    2016-01-01

    Full Text Available Development of a transport complex of the region and transport servicing becomes more and more urgent every year and exerts the increasing impact on development of the region in general. In article basic provisions of transport servicing of economy of the region are determined. On the basis of a research of approaches to determination of transport servicing the author's understanding of this process is provided. The system of transport servicing of the region is considered as set of elements of transport infrastructure through which interaction the needs for cargo transfer and passengers in the region are satisfied. It is the open system having the isolated internal environment and interacting with the external environment. At the same time the internal environment consists of elements between which communication is much stronger, than with the elements constituting the external environment. In market conditions the urgent problem of uncertainty of the external environment influences in turn a condition and development of system of transport servicing of the region, changing external and internal conditions of its functioning. The characteristic of system of transport servicing of the region is provided. Methods of regulation of transport servicing are determined. Features of transport servicing of economy of the region are marked out: need of updating of a property, plant and equipment on transport and development of transport infrastructure; insufficient development of strategic planning of transport as single complex within transport system and in a general context of development of productive forces; the low investment and innovative activity in a motor transportation industry caused by reducing internal and foreign investments, decrease in financing from the government budget. The research of a condition of standard legal support of development of a transport complex in the Voronezh region is conducted, the analysis of the strategic and

  11. Energy transport

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    The measurement of primary interaction cross sections and the incorporation of these data into Monte Carlo calculations provide detailed information about the initial spatial distribution of absorbed dose. Our theoretical energy transport studies have focused on the use of this information to predict the evolution of chemical species formed as a result of the energy deposition. This effort has led to a stochastic approach to diffusion kinetics that can account for the influence of track structure on the yield of free radicals in the radiolysis of water. Fluorescence studies with pulsed alpha particle and proton beams provided the first experimental test of our stochastic model of tract structure effects. Our experimental studies use time-resolved emission spectroscopy to investigate the mechanism of energy transport in nonpolar liquids. Studies of the concentration dependence of time-resolved emission from solutions of benzene in cyclohexane also show the importance of using low benzene concentrations to minimize the influence of benzene dimers on the emission kinetics

  12. COLLOID-FACILITATED TRANSPORT OF RADIONUCLIDES THROUGH THE VADOSE ZONE

    International Nuclear Information System (INIS)

    Flury, Markus

    2003-01-01

    Contaminants have leaked into the vadose zone at the USDOE Hanford reservation. It is important to understand the fate and transport of these contaminants to design remediation strategies and long-term waste management plans at the Hanford reservation. Colloids may play an important role in fate and transport of strongly sorbing contaminants, such as Cs or Pu. This project seeks to improve the basic understanding of colloid and colloid-facilitated transport of contaminants in the vadose zone. The specific objectives addressed are: (1) Determine the structure, composition, and surface charge characteristics of colloidal particles formed under conditions similar to those occurring during leakage of waste typical of Hanford tank supernatants into soils and sediments surrounding the tanks. (2) Characterize the mutual interactions between colloids, contaminant, and soil matrix in batch experiments under various ionic strength and pH conditions. We will investigate the nature of the solid-liquid interactions and the kinetics of the reactions. (3) Evaluate mobility of colloids through soil under different degrees of water saturation and solution chemistry (ionic strength and pH). (4) Determine the potential of colloids to act as carriers to transport the contaminant through the vadose zone and verify the results through comparison with field samples collected under leaking tanks. (5) Improve conceptual characterization of colloid-contaminant-soil interactions and colloid-facilitated transport for implementation into reactive chemical transport models. This project was in part supported by an NSF-IGERT grant to Washington State University. The IGERT grant provided funding for graduate student research and education, and two graduate students were involved in the EMSP project. The IGERT program also supported undergraduate internships. The project is part of a larger EMSP program to study fate and transport of contaminants under leaking Hanford waste tanks. The project has

  13. Nano and Mesoscale Ion and Water Transport in Perfluorosulfonic AcidMembranes

    Science.gov (United States)

    2017-10-01

    Nano- and Mesoscale Ion and Water Transport in Perfluorosulfonic-Acid Membranes A. R. Crothers a,b , C. J. Radke a,b , A. Z. Weber a a...Berkeley, CA 94720, USA Water and aqueous cations transport along multiple length scales in perfluorosulfonic-acid membranes. Molecular interactions...as a function of hydration. A resistor network upscales the nanoscale properties to predict effective membrane ion and water transport and their

  14. Grapefruit and drug interactions.

    Science.gov (United States)

    2012-12-01

    Since the late 1980s, grapefruit juice has been known to affect the metabolism of certain drugs. Several serious adverse effects involving drug interactions with grapefruit juice have been published in detail. The components of grapefruit juice vary considerably depending on the variety, maturity and origin of the fruit, local climatic conditions, and the manufacturing process. No single component accounts for all observed interactions. Other grapefruit products are also occasionally implicated, including preserves, lyophylised grapefruit juice, powdered whole grapefruit, grapefruit seed extract, and zest. Clinical reports of drug interactions with grapefruit juice are supported by pharmacokinetic studies, each usually involving about 10 healthy volunteers, in which the probable clinical consequences were extrapolated from the observed plasma concentrations. Grapefruit juice inhibits CYP3A4, the cytochrome P450 isoenzyme most often involved in drug metabolism. This increases plasma concentrations of the drugs concerned, creating a risk of overdose and dose-dependent adverse effects. Grapefruit juice also inhibits several other cytochrome P450 isoenzymes, but they are less frequently implicated in interactions with clinical consequences. Drugs interacting with grapefruit and inducing serious clinical consequences (confirmed or very probable) include: immunosuppressants, some statins, benzodiazepines, most calcium channel blockers, indinavir and carbamazepine. There are large inter-individual differences in enzyme efficiency. Along with the variable composition of grapefruit juice, this makes it difficult to predict the magnitude and clinical consequences of drug interactions with grapefruit juice in a given patient. There is increasing evidence that transporter proteins such as organic anion transporters and P-glycoprotein are involved in interactions between drugs and grapefruit juice. In practice, numerous drugs interact with grapefruit juice. Although only a few

  15. Phonon limited electronic transport in Pb

    DEFF Research Database (Denmark)

    Rittweger, Florian; Hinsche, Nicki Frank; Mertig, Ingrid

    2017-01-01

    We present a fully ab initio based scheme to compute electronic transport properties, i.e. the electrical conductivity σ and thermopower S, in the presence of electron-phonon interaction. We explicitly investigate the k-dependent structure of the Éliashberg spectral function, the coupling strength...

  16. Complement Activation by Ceramide Transporter Proteins

    NARCIS (Netherlands)

    Bode, G.H.; Losen, M.; Buurman, W.A.; Veerhuis, R.; Molenaar, P.C.; Steinbusch, H.W.M.; De Baets, M.H.; Daha, MR; Martinez-Martinez, P.

    2014-01-01

    C1q is the initiator of the classical complement pathway and, as such, is essential for efficient opsonization and clearance of pathogens, altered self-structures, and apoptotic cells. The ceramide transporter protein (CERT) and its longer splicing isoform CERTL are known to interact with

  17. Prediction of transport phenomena in near and far field: interaction solid phase/fluid phase

    International Nuclear Information System (INIS)

    Mingarro, E.

    1995-01-01

    The prediction of transport phenomena in near and far field is presented in the present report. The study begins with the analysis of solid phases stability: solubility of storage waste: UO 2 and solubility of radionuclides the redox and sorption-desorption conditions are the last aspects studied to predict the transport phenomena

  18. Interactions of [14C]phosphonoformic acid with renal cortical brush-border membranes. Relationship to the Na+-phosphate co-transporter

    International Nuclear Information System (INIS)

    Szczepanska-Konkel, M.; Yusufi, A.N.; Dousa, T.P.

    1987-01-01

    Since phosphonoformic acid (PFA) acts as a specific competitive inhibitor of Na+-Pi co-transport across renal brush-border membrane (BBM), we employed the [ 14 C]PFA as a probe to determine the mechanism of its interaction with rat renal BBM. The binding of [ 14 C]PFA to BBM vesicles (BBMV), with Na+ present in extravesicular medium (Na+o), was time- and temperature-dependent. The replacement of Na+o with other monovalent cations reduced the PFA binding by -80%. Cl- was the most effective accompanying monovalent anion as NaCl for maximum PFA binding. The Na+o increased the apparent affinity of BBMV for [ 14 C]PFA binding, but it did not change the maximum binding capacity. The maximum [ 14 C]PFA binding was achieved at Na+o approximately equal to 50 mM. The extent of Na+-dependent [ 14 C]PFA binding correlated with percent inhibition by an equimolar dose of PFA of the dependent BBMV uptake of 32Pi. Intravesicular Na+ (Na+i) decreased [ 14 C]PFA binding, on BBMV, and this inhibition by Na+i was dependent on the presence of Na+o. The increase in Na+i, at constant [Na+]o, decreased the Vmax, but not the Km, for [ 14 C]PFA binding on BBMV. Bound [ 14 C]PFA was displaced from BBMV by phosphonocarboxylic acids proportionally to their ability to inhibit gradient-dependent Pi transport, whereas other monophosphonates, diphosphonates, L-proline, or D-glucose did not influence the [ 14 C]PFA binding. The Na+-dependent binding of [ 14 C]PFA and of [ 3 H]phlorizin by BBMV was 10 times higher than binding of these ligands to renal basolateral membranes and to mitochondria. [ 14 C]PFA probably binds onto the same locus on the luminal surface of BBM, where Pi and Na+ form a ternary complex with the Na+-Pi co-transporter

  19. Modified finite element transport model, FETRA, for sediment and radionuclide migration in open coastal waters

    International Nuclear Information System (INIS)

    Onishi, Y.; Arnold, E.M.; Mayer, D.W.

    1979-08-01

    The finite element model, FETRA, simulates transport of sediment and radionuclides (and other contaminants, such as heavy metals, pesticides, and other toxic substances) in surface water bodies. The model is an unsteady, two-dimensional (longitudinal and lateral) model which consists of the following three submodels coupled to include sediment-contaminant interactions: (1) sediment transport submodel, (2) dissolved contaminant transport submodel, and (3) particulate contaminant (contaminant adsorbed by sediment) transport submodel. Under the current phase of the study, FETRA was modified to include sediment-wave interaction in order to extend the applicability of the model to coastal zones and large lakes (e.g., the Great Lakes) where wave actions can be one of the dominant mechanisms to transport sediment and toxic contaminant. FETRA was further modified to handle both linear and quadratic approximations to velocity and depth distributions in order to be compatible with various finite element hydrodynamic models (e.g., RMA II and CAFE) which supply hydrodynamic input data to FETRA. The next step is to apply FETRA to coastal zones to simulate transport of sediment and radionuclides with their interactions in order to test and verify the model under marine and large lacustrine environments

  20. Interactions of [3H]amphetamine with rat brain synaptosomes. II. Active transport

    International Nuclear Information System (INIS)

    Zaczek, R.; Culp, S.; De Souza, E.B.

    1991-01-01

    The accumulation of 5 nM d-[ 3 H]amphetamine (d-[ 3 H]AMPH) into rat brain synaptosomes was examined using physiological buffer conditions. The accumulation of d-[ 3 H]AMPH into striatal synaptosomes was saturable, of high affinity, ouabain-sensitive and temperature-dependent, suggesting an active transport phenomenon. Eadee-Hofstee analysis of striatal d-[ 3 H]AMPH transport (AMT) saturation isotherms indicated an apparent Km of 97 nM and a Vmax of 3.0 fmol/mg tissue/min. Lesion of the striatal dopaminergic innervation led to equivalent decreases of [ 3 H] dopamine (DA) transport and AMT, indicating that AMT occurs in DA terminals. Furthermore, AMT was not evident in cerebral cortex, a brain region with a paucity of DA terminals. In competition studies, AMT was stereospecific; d-AMPH (IC50 = 60 nM) was an 8-fold more potent inhibitor of the transport than its I-isomer (IC50 = 466 nM). DA(IC50 = 257 nM), DA uptake blockers and substrates were found to be potent inhibitors of AMT: GBR12909 IC50 = 5 nM; methamphetamine IC50 = 48 nM; methylphenidate IC50 = 53 nM; and cocaine IC50 = 172 nM. In contrast, serotonin was relatively weak in inhibiting AMT (IC50 = 7.9 microM). There was a highly significant (P less than .001; slope = 1.2) linear correlation between the AMT-inhibiting potencies of AMPH analogs and their potencies in stimulating locomotor activity in rodents. AMT may be important in the low dose effects of AMPH such as increased locomotor activity in rodents and stimulant activity in man. Differences between AMT and d-[ 3 H]AMPH sequestration described earlier, as well as their possible relevance to behavioral and neurochemical sequelae of AMPH administration are also discussed

  1. Transport through hybrid superconducting/normal nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Futterer, David

    2013-01-29

    We mainly investigate transport through interacting quantum dots proximized by superconductors. For this purpose we extend an existing theory to describe transport through proximized quantum dots coupled to normal and superconducting leads. It allows us to study the influence of a strong Coulomb interaction on Andreev currents and Josephson currents. This is a particularly interesting topic because it combines two competing properties: in superconductors Cooper pairs are formed by two electrons which experience an attractive interaction while two electrons located on a quantum dot repel each other due to the Coulomb interaction. It seems at first glance that transport processes involving Cooper pairs should be suppressed because of the two competing interactions. However, it is possible to proximize the dot in nonequilibrium situations. At first, we study a setup composed of a quantum dot coupled to one normal, one ferromagnetic, and one superconducting lead in the limit of an infinitely-large superconducting gap. Within this limit the coupling between dot and superconductor is described exactly by the presented theory. It leads to the formation of Andreev-bound states (ABS) and an additional bias scheme opens in which a pure spin current, i.e. a spin current with a vanishing associated charge current, can be generated. In a second work, starting from the infinite-gap limit, we perform a systematic expansion of the superconducting gap around infinity and investigate Andreev currents and Josephson currents. This allows us to estimate the validity of infinite-gap calculations for real systems in which the superconducting gap is usually a rather small quantity. We find indications that a finite gap renormalizes the ABS and propose a resummation approach to explore the finite-gap ABS. Despite the renormalization effects the modifications of transport by finite gaps are rather small. This result lets us conclude that the infinite-gap calculation is a valuable tool to

  2. Transport through hybrid superconducting/normal nanostructures

    International Nuclear Information System (INIS)

    Futterer, David

    2013-01-01

    We mainly investigate transport through interacting quantum dots proximized by superconductors. For this purpose we extend an existing theory to describe transport through proximized quantum dots coupled to normal and superconducting leads. It allows us to study the influence of a strong Coulomb interaction on Andreev currents and Josephson currents. This is a particularly interesting topic because it combines two competing properties: in superconductors Cooper pairs are formed by two electrons which experience an attractive interaction while two electrons located on a quantum dot repel each other due to the Coulomb interaction. It seems at first glance that transport processes involving Cooper pairs should be suppressed because of the two competing interactions. However, it is possible to proximize the dot in nonequilibrium situations. At first, we study a setup composed of a quantum dot coupled to one normal, one ferromagnetic, and one superconducting lead in the limit of an infinitely-large superconducting gap. Within this limit the coupling between dot and superconductor is described exactly by the presented theory. It leads to the formation of Andreev-bound states (ABS) and an additional bias scheme opens in which a pure spin current, i.e. a spin current with a vanishing associated charge current, can be generated. In a second work, starting from the infinite-gap limit, we perform a systematic expansion of the superconducting gap around infinity and investigate Andreev currents and Josephson currents. This allows us to estimate the validity of infinite-gap calculations for real systems in which the superconducting gap is usually a rather small quantity. We find indications that a finite gap renormalizes the ABS and propose a resummation approach to explore the finite-gap ABS. Despite the renormalization effects the modifications of transport by finite gaps are rather small. This result lets us conclude that the infinite-gap calculation is a valuable tool to

  3. Implementation of sorption hysteresis in multi-Fickian moisture transport

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Svensson, Staffan

    2007-01-01

    In the cellular structure of wood, bound-water diffusion and water-vapor diffusion interact via sorption in a complex moisture-transportation system. At low relative humidities, moisture transport may be modeled by a Fickian diffusion equation with a good approximation. At higher relative......-35% in moisture content. Hence, for a precise moisture content computation, sorption hysteresis must be taken into account. The present paper explains the relation between sorption hysteresis and multi-Fickian moisture transport, and clarifies how models for the two phenomena are coupled. To illustrate...

  4. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system; Modelisation couplee (transport - reaction) des interactions fluides - argiles et de leurs effets en retour sur les proprietes physiques de barrieres ouvragees en bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Marty, N

    2006-11-15

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  5. Contaminant geochemistry. Interactions and transport in the subsurface environment

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, Brian; Dror, Ishai; Yaron, Bruno [Weizmann Institute of Science, Rehovot (Israel). Dept. of Environmental Sciences and Energy Research

    2008-07-01

    This book combines earth science, subsurface hydrology and environmental geochemistry, providing a comprehensive background for specialists interested in the protection and sustainable management of the subsurface environment. The reader is introduced to the chemistry of contaminants, which usually disturb the natural equilibrium in the subsurface as a result of human activity. The major focus of the book is on contaminant reactions in soil solutions, groundwater and porous media solid phases, accounting for their persistence and transformation in the subsurface, as they are transported from the land surface into groundwater. Discussions on selected case studies are provided. (orig.)

  6. Interplay of drug metabolizing enzymes with cellular transporters.

    Science.gov (United States)

    Böhmdorfer, Michaela; Maier-Salamon, Alexandra; Riha, Juliane; Brenner, Stefan; Höferl, Martina; Jäger, Walter

    2014-11-01

    Many endogenous and xenobiotic substances and their metabolites are substrates for drug metabolizing enzymes and cellular transporters. These proteins may not only contribute to bioavailability of molecules but also to uptake into organs and, consequently, to overall elimination. The coordinated action of uptake transporters, metabolizing enzymes, and efflux pumps, therefore, is a precondition for detoxification and elimination of drugs. As the understanding of the underlying mechanisms is important to predict alterations in drug disposal, adverse drug reactions and, finally, drug-drug interactions, this review illustrates the interplay between selected uptake/efflux transporters and phase I/II metabolizing enzymes.

  7. Transport and interaction of a relativistic electron beam in low pressure neutral gases

    International Nuclear Information System (INIS)

    Iyyengar, S.K.; Rohatgi, V.K.

    1989-01-01

    A numerical study of the transport of a 0.27-MeV, 6.6-kA, 40-ns relativistic electron beam in argon and hydrogen in the pressure range of 0.01--1.0 Torr taking into account charge and current neutralization effects is presented. Ionization by avalanching and by beam and plasma electrons is included in the calculation of plasma density buildup. Plasma heating resulting from return current heating and two-stream instability is taken into account. The computed results of charge transport, net current, and breakdown time are compared with experimental results obtained in this laboratory. The results are in reasonable agreement with the experiment and show a maximum charge transport of 75% at the optimum pressure of 0.1 and 0.6 Torr in argon and hydrogen, respectively. The calculations indicate beam-generated plasma parameters of 10 19 --10 20 m -3 density and 1--5 eV electron temperature

  8. Investment in transport infrastructure, regulation, and gas-gas competition

    Energy Technology Data Exchange (ETDEWEB)

    Gasmi, Farid [Toulouse School of Economics (ARQADE and IDEI), Universite Toulouse 1 Capitole (France); Oviedo, Juan Daniel [Universidad del Rosario (Colombia)

    2010-05-15

    This paper develops a simple model in which a regulated (upstream) transporter provides capacity to a marketer competing in output with an incumbent in the (downstream) gas commodity market. The equilibrium outcome of the firms' interaction in the downstream market is explicitly taken into account by the regulator when setting the transport charge. We consider various forms of competition in this market and derive the corresponding optimal transport charge policies. We then run simulations that allow us to perform a comparative welfare analysis of these transport infrastructure investment policies based on different assumptions about the intensity of the competition that prevails in the gas commodity market. (author)

  9. Investment in transport infrastructure, regulation, and gas-gas competition

    International Nuclear Information System (INIS)

    Gasmi, Farid; Oviedo, Juan Daniel

    2010-01-01

    This paper develops a simple model in which a regulated (upstream) transporter provides capacity to a marketer competing in output with an incumbent in the (downstream) gas commodity market. The equilibrium outcome of the firms' interaction in the downstream market is explicitly taken into account by the regulator when setting the transport charge. We consider various forms of competition in this market and derive the corresponding optimal transport charge policies. We then run simulations that allow us to perform a comparative welfare analysis of these transport infrastructure investment policies based on different assumptions about the intensity of the competition that prevails in the gas commodity market. (author)

  10. The research into development of passanger transport by land

    Directory of Open Access Journals (Sweden)

    J. Butkevičius

    2004-10-01

    Full Text Available This is the first scientific work in Lithuania carrying out a complex research into passenger transport by land, covering all problematic issues related to the field such as development, market planning, organization, management, competition, contractual relations, financing, development of transport technologies, implementation of new transport technologies elaborating the theoretical base for the development of passenger transport. The research shows the analysis of the movement of passenger transport volumes and determines the regularity of these changes. The forecast of passenger transport by land is based on a multiple analysis. The work determines the perspective markets of rail and road transport as well as elaborates the principles of the improvement of road and rail transport interaction.The author originates the principles of the development of passenger transport technologies and the principles of the implementation of advanced technologies. The author also founds the principles of planning, organization and management of land transport as well as the principles of security of equal conditions of competition and contractual relations between customers and haulers.

  11. Far SOL transport and main wall plasma interaction in DIII-D

    International Nuclear Information System (INIS)

    Rudakov, D.L.; Boedo, J.A.; Moyer, R.A.; Doerner, R.P.; Hollmann, E.M.; Krasheninnikov, S.I.; Pigarov, A.Yu.; Stangeby, P.C.; McLean, A.G.; Watkins, J.G.; Wampler, W.R.; Whyte, D.G.; McKee, G.R.; Zeng, L.; Wang, G.; Brooks, N.H.; Evans, T.E.; Leonard, A.W.; Mahdavi, M.A.; West, W.P.; Wong, C.P.C.; Fenstermacher, M.E.; Groth, M.; Lasnier, C.J.

    2005-01-01

    Far scrape-off layer (SOL) and near-wall plasma parameters in DIII-D depend strongly on the discharge parameters and confinement regime. In L-mode discharges cross-field transport increases with the average discharge density and flattens far SOL profiles, thus increasing plasma-wall contact. In H-mode between edge localized modes (ELMs), plasma-wall contact is generally weaker than in L-mode. During ELMs plasma fluxes to the wall increase to, or above the L-mode levels. Depending on the discharge conditions ELMs are responsible for 30-90% of the ion flux to the outboard chamber wall. Cross-field fluxes in far SOL are dominated by large amplitude intermittent transport events that may propagate all the way to the outer wall and cause sputtering. A Divertor Material Evaluation System (DiMES) probe containing samples of several ITER-relevant materials including carbon, beryllium and tungsten was exposed to a series of upper single null (USN) discharges as a proxy to measure the first wall erosion. (author)

  12. Grain transport mechanics in shallow flow

    Science.gov (United States)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flows. The two-phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a dispe...

  13. Axisymmetric tokamak scapeoff transport

    International Nuclear Information System (INIS)

    Singer, C.E.; Langer, W.D.

    1982-08-01

    We present the first self-consistent estimate of the magnitude of each term in a fluid treatment of plasma transport for a plasma lying in regions of open field lines in an axisymmetric tokamak. The fluid consists of a pure hydrogen plasma with sources which arise from its interaction with neutral hydrogen atoms. The analysis and results are limited to the high collisionality regime, which is optimal for a gaseous neutralizer divertor, or to a cold plasma mantle in a tokamak reactor. In this regime, both classical and neoclassical transport processes are important, and loss of particles and energy by diamagnetic flow are also significant. The prospect of extending the analysis to the lower collisionality regimes encountered in many existing experiments is discussed

  14. Aquaporin Protein-Protein Interactions

    Directory of Open Access Journals (Sweden)

    Jennifer Virginia Roche

    2017-10-01

    Full Text Available Aquaporins are tetrameric membrane-bound channels that facilitate transport of water and other small solutes across cell membranes. In eukaryotes, they are frequently regulated by gating or trafficking, allowing for the cell to control membrane permeability in a specific manner. Protein–protein interactions play crucial roles in both regulatory processes and also mediate alternative functions such as cell adhesion. In this review, we summarize recent knowledge about aquaporin protein–protein interactions; dividing the interactions into three types: (1 interactions between aquaporin tetramers; (2 interactions between aquaporin monomers within a tetramer (hetero-tetramerization; and (3 transient interactions with regulatory proteins. We particularly focus on the structural aspects of the interactions, discussing the small differences within a conserved overall fold that allow for aquaporins to be differentially regulated in an organism-, tissue- and trigger-specific manner. A deep knowledge about these differences is needed to fully understand aquaporin function and regulation in many physiological processes, and may enable design of compounds targeting specific aquaporins for treatment of human disease.

  15. Specific effects of c-Jun NH2-terminal kinase-interacting protein 1 in neuronal axons

    Directory of Open Access Journals (Sweden)

    Shu Tang

    2016-01-01

    Full Text Available c-Jun NH2-terminal kinase (JNK-interacting protein 3 plays an important role in brain-derived neurotrophic factor/tropomyosin-related kinase B (TrkB anterograde axonal transport. It remains unclear whether JNK-interacting protein 1 mediates similar effects, or whether JNK-interacting protein 1 affects the regulation of TrkB anterograde axonal transport. In this study, we isolated rat embryonic hippocampus and cultured hippocampal neurons in vitro. Coimmunoprecipitation results demonstrated that JNK-interacting protein 1 formed TrkB complexes in vitro and in vivo. Immunocytochemistry results showed that when JNK-interacting protein 1 was highly expressed, the distribution of TrkB gradually increased in axon terminals. However, the distribution of TrkB reduced in axon terminals after knocking out JNK-interacting protein 1. In addition, there were differences in distribution of TrkB after JNK-interacting protein 1 was knocked out compared with not. However, knockout of JNK-interacting protein 1 did not affect the distribution of TrkB in dendrites. These findings confirm that JNK-interacting protein 1 can interact with TrkB in neuronal cells, and can regulate the transport of TrkB in axons, but not in dendrites.

  16. Intestinal transporters for endogenic and pharmaceutical organic anions

    DEFF Research Database (Denmark)

    Grandvuinet, Anne Sophie; Vestergaard, Henrik Tang; Rapin, Nicolas

    2012-01-01

    This review provides an overview of intestinal human transporters for organic anions and stresses the need for standardization of the various in-vitro methods presently employed in drug-drug interaction (DDI) investigations....

  17. Rate and Regulation of Copper Transport by Human Copper Transporter 1 (hCTR1)*

    Science.gov (United States)

    Maryon, Edward B.; Molloy, Shannon A.; Ivy, Kristin; Yu, Huijun; Kaplan, Jack H.

    2013-01-01

    Human copper transporter 1 (hCTR1) is a homotrimer of a 190-amino acid monomer having three transmembrane domains believed to form a pore for copper permeation through the plasma membrane. The hCTR1-mediated copper transport mechanism is not well understood, nor has any measurement been made of the rate at which copper ions are transported by hCTR1. In this study, we estimated the rate of copper transport by the hCTR1 trimer in cultured cells using 64Cu uptake assays and quantification of plasma membrane hCTR1. For endogenous hCTR1, we estimated a turnover number of about 10 ions/trimer/s. When overexpressed in HEK293 cells, a second transmembrane domain mutant of hCTR1 (H139R) had a 3-fold higher Km value and a 4-fold higher turnover number than WT. Truncations of the intracellular C-terminal tail and an AAA substitution of the putative metal-binding HCH C-terminal tripeptide (thought to be required for transport) also exhibited elevated transport rates and Km values when compared with WT hCTR1. Unlike WT hCTR1, H139R and the C-terminal mutants did not undergo regulatory endocytosis in elevated copper. hCTR1 mutants combining methionine substitutions that block transport (M150L,M154L) on the extracellular side of the pore and the high transport H139R or AAA intracellular side mutations exhibited the blocked transport of M150L,M154L, confirming that Cu+ first interacts with the methionines during permeation. Our results show that hCTR1 elements on the intracellular side of the hCTR1 pore, including the carboxyl tail, are not essential for permeation, but serve to regulate the rate of copper entry. PMID:23658018

  18. The Science of Transportation Analysis and Simulation

    Science.gov (United States)

    Gleibe, John

    2010-03-01

    Transportation Science focuses on methods developed to model and analyze the interaction between human behavior and transportation systems. From the human behavioral, or demand, perspective, we are interested in how person and households organize their activities across space and time, with travel viewed as an enabling activity. We have a particular interest in how to model the range of responses to public policy and transportation system changes, which leads to the consideration of both short- and long-term decision-making, interpersonal dependencies, and non-transportation-related opportunities and constraints, including household budgets, land use systems and economic systems. This has led to the development of complex structural econometric modeling systems as well as agent-based simulations. From the transportation systems, or supply, perspective we are interested in the level of service provide by transportation facilities, be it auto, transit or multi-modal systems. This has led to the development of network models and equilibrium concepts as well as hybrid simulation systems based on concepts borrowed from physics, such as fluid flow models, and cellular automata-type models. In this presentation, we review a representative sample of these methods and their use in transportation planning and public policy analysis.

  19. Transport Statistics - Transport - UNECE

    Science.gov (United States)

    Sustainable Energy Statistics Trade Transport Themes UNECE and the SDGs Climate Change Gender Ideas 4 Change UNECE Weekly Videos UNECE Transport Areas of Work Transport Statistics Transport Transport Statistics About us Terms of Reference Meetings and Events Meetings Working Party on Transport Statistics (WP.6

  20. Electronic Transport in Two-Dimensional Materials

    Science.gov (United States)

    Sangwan, Vinod K.; Hersam, Mark C.

    2018-04-01

    Two-dimensional (2D) materials have captured the attention of the scientific community due to the wide range of unique properties at nanometer-scale thicknesses. While significant exploratory research in 2D materials has been achieved, the understanding of 2D electronic transport and carrier dynamics remains in a nascent stage. Furthermore, because prior review articles have provided general overviews of 2D materials or specifically focused on charge transport in graphene, here we instead highlight charge transport mechanisms in post-graphene 2D materials, with particular emphasis on transition metal dichalcogenides and black phosphorus. For these systems, we delineate the intricacies of electronic transport, including band structure control with thickness and external fields, valley polarization, scattering mechanisms, electrical contacts, and doping. In addition, electronic interactions between 2D materials are considered in the form of van der Waals heterojunctions and composite films. This review concludes with a perspective on the most promising future directions in this fast-evolving field.

  1. Transport of microplastics in coastal seas

    Science.gov (United States)

    Zhang, Hua

    2017-12-01

    Microplastic pollution of the marine environment has received increasing attention from scientists, the public, and policy makers over the last few years. Marine microplastics predominantly originate near the coast and can remain in the nearshore zone for some time. However, at present, there is little understanding of the fate and transport of microplastics in coastal regions. This paper provides a comprehensive overview of the physical processes involved in the movement of microplastics from estuaries to the continental shelf. The trajectory and speed of microplastics are controlled by their physical characteristics (density, size, and shape) and ocean dynamic conditions (wind, waves, tides, thermohaline gradients, and the influence of benthic sediments). Microplastic particles can be subjected to beaching, surface drifting, vertical mixing, and biofouling, as well as bed-load and suspended load transport processes, until reaching terminal deposition on beaches, in coastal marshes, in benthic sediments or until they are carried by ocean currents to subtropical convergence zones. The dynamic interaction of released microplastics with the shoreline is regulated by onshore/offshore transport, which is impacted by the source location as well as the geometry, vegetation, tidal regime, and wave direction. Wind and wave conditions dominate surface drifting of buoyant particles through Ekman drift, windage, and Stokes drift mechanisms. Neustic microplastic particles travel in the subsurface because of vertical mixing through wind-driven Langmuir circulation and heat cycling. Increasing accumulation of microplastics in benthic sediments needs to be quantitatively explored in terms of biofouling, deposition, entrainment, and transport dynamics. Further studies are required to understand the following: 1) the primary parameters (e.g., windage, terminal velocity, diffusivity, critical shear stress) that determine microplastic transport in different pathways; 2) dynamic

  2. Tariff Policy and Transport Costs under Reciprocal Dumping

    OpenAIRE

    Jun Oshiro

    2011-01-01

    This paper analyzes tariff competition by investigating the strategic interactions among firms that are highly mobile across national boundaries. Although high transport costs yield a geographic dispersion of the industry, sufficiently low transport costs result in a core-periphery location where nobody bears tariff burdens. In any case, the world economy would be in a much better position under an international coordination scheme. An economy is only required to enforce a weak international ...

  3. INVESTIGATING THE ROLE OF PDZ-DOMAIN INTERACTIONS FOR DOPAMINE TRANSPORTER FUNCTION

    DEFF Research Database (Denmark)

    Fog, Jacob; Vægter, Christian Bjerggaard; Gether, Ulrik

    canonical PDZ domain interactions with proteins such as PICK1. To clarify the actual role of PDZ domain interactions for DAT function we have expressed the wild type DAT and a number of C-terminal mutants either alone or together with PICK1 in HEK293, N2A neuroblastoma and PC12 cells. Data obtained from...

  4. Safe transport of tritium-producing burnable absorber rods: Intergovernmental regulations perspective

    International Nuclear Information System (INIS)

    Steinhoff, R.L.; Patterson, J.; Helvey, E.

    2000-01-01

    The state, tribal, and local governments along the shipment corridors share the US Department of Energy's (DOE's) goal of safe and uneventful radioactive materials transportation. The various governmental bodies involved can have different interpretations of a safe and uneventful shipping campaign. However, that gap has narrowed in recent years, due in part to improved coordination among DOE and the affected states, tribes, and municipal governments. This paper describes how the interactions between a new DOE radioactive materials transportation program and the corridor governments bridged that gap to create a shipping campaign that most of those involved viewed as safer and more publicly acceptable than had the process not occurred. It also describes the successful interaction between two DOE shipment campaigns transporting along much of the same route during the same time period

  5. Thermodynamics of competitive molecular channel transport: application to artificial nuclear pores.

    Science.gov (United States)

    Bauer, Wolfgang R; Nadler, Walter

    2010-12-13

    In an analytical model channel transport is analyzed as a function of key parameters, determining efficiency and selectivity of particle transport in a competitive molecular environment. These key parameters are the concentration of particles, solvent-channel exchange dynamics, as well as particle-in-channel- and interparticle interaction. These parameters are explicitly related to translocation dynamics and channel occupation probability. Slowing down the exchange dynamics at the channel ends, or elevating the particle concentration reduces the in-channel binding strength necessary to maintain maximum transport. Optimized in-channel interaction may even shift from binding to repulsion. A simple equation gives the interrelation of access dynamics and concentration at this transition point. The model is readily transferred to competitive transport of different species, each of them having their individual in-channel affinity. Combinations of channel affinities are determined which differentially favor selectivity of certain species on the cost of others. Selectivity for a species increases if its in-channel binding enhances the species' translocation probability when compared to that of the other species. Selectivity increases particularly for a wide binding site, long channels, and fast access dynamics. Recent experiments on competitive transport of in-channel binding and inert molecules through artificial nuclear pores serve as a paradigm for our model. It explains qualitatively and quantitatively how binding molecules are favored for transport at the cost of the transport of inert molecules.

  6. Optical absorption and energy transport in compact dendrimers with unsymmetrical branching

    International Nuclear Information System (INIS)

    Supritz, C.; Gounaris, V.; Reineker, P.

    2008-01-01

    We investigate the linear optical absorption and the energy transport in compact dendrimers with unsymmetrical branching, using the Frenkel exciton concept. The electron-phonon interaction is taken into account by introducing a heat bath that interacts with the exciton in a stochastic manner

  7. Source-to-sink transport of sugar and regulation by environmental factors.

    Science.gov (United States)

    Lemoine, Remi; La Camera, Sylvain; Atanassova, Rossitza; Dédaldéchamp, Fabienne; Allario, Thierry; Pourtau, Nathalie; Bonnemain, Jean-Louis; Laloi, Maryse; Coutos-Thévenot, Pierre; Maurousset, Laurence; Faucher, Mireille; Girousse, Christine; Lemonnier, Pauline; Parrilla, Jonathan; Durand, Mickael

    2013-01-01

    Source-to-sink transport of sugar is one of the major determinants of plant growth and relies on the efficient and controlled distribution of sucrose (and some other sugars such as raffinose and polyols) across plant organs through the phloem. However, sugar transport through the phloem can be affected by many environmental factors that alter source/sink relationships. In this paper, we summarize current knowledge about the phloem transport mechanisms and review the effects of several abiotic (water and salt stress, mineral deficiency, CO2, light, temperature, air, and soil pollutants) and biotic (mutualistic and pathogenic microbes, viruses, aphids, and parasitic plants) factors. Concerning abiotic constraints, alteration of the distribution of sugar among sinks is often reported, with some sinks as roots favored in case of mineral deficiency. Many of these constraints impair the transport function of the phloem but the exact mechanisms are far from being completely known. Phloem integrity can be disrupted (e.g., by callose deposition) and under certain conditions, phloem transport is affected, earlier than photosynthesis. Photosynthesis inhibition could result from the increase in sugar concentration due to phloem transport decrease. Biotic interactions (aphids, fungi, viruses…) also affect crop plant productivity. Recent breakthroughs have identified some of the sugar transporters involved in these interactions on the host and pathogen sides. The different data are discussed in relation to the phloem transport pathways. When possible, the link with current knowledge on the pathways at the molecular level will be highlighted.

  8. Molecular interactions and thermal transport in ionic liquids with carbon nanomaterials.

    Science.gov (United States)

    França, João M P; Nieto de Castro, Carlos A; Pádua, Agílio A H

    2017-07-05

    We used molecular dynamics simulation to study the effect of suspended carbon nanomaterials, nanotubes and graphene sheets, on the thermal conductivity of ionic liquids, an issue related to understanding the properties of nanofluids. One important aspect that we developed is an atomistic model of the interactions between the organic ions and carbon nanomaterials, so we did not rely on existing force fields for small organic molecules or assume simple combining rules to describe the interactions at the liquid/material interface. Instead, we used quantum calculations with a density functional suitable for non-covalent interactions to parameterize an interaction model, including van der Waals terms and also atomic partial charges on the materials. We fitted a n-m interaction potential function with n values of 9 or 10 and m values between 5 and 8, so a 12-6 Lennard-Jones function would not fit the quantum calculations. For the atoms of ionic liquids and carbon nanomaterials interacting among themselves, we adopted existing models from the literature. We studied the imidazolium ionic liquids [C 4 C 1 im][SCN], [C 4 C 1 im][N(CN) 2 ], [C 4 C 1 im][C(CN) 3 ] and [C 4 C 1 im][(CF 3 SO 2 ) 2 N]. Attraction is stronger for cations (than for anions) above and below the π-system of the nanomaterials, whereas anions show stronger attraction for the hydrogenated edges. The ordering of ions around and inside (7,7) and (10,10) single-walled nanotubes, and near a stack of graphene sheets, was analysed in terms of density distribution functions. We verified that anions are found, as well as cations, in the first interfacial layer interacting with the materials, which is surprising given the interaction potential surfaces. The thermal conductivity of the ionic liquids and of composite systems containing one nanotube or one graphene stack in suspension was calculated using non-equilibrium molecular dynamics. Thermal conductivity was calculated along the axis of the nanotube and

  9. Decoupled electron and phonon transports in hexagonal boron nitride-silicene bilayer heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yongqing; Pei, Qing-Xiang, E-mail: peiqx@ihpc.a-star.edu.sg, E-mail: zhangg@ihpc.a-star.edu.sg; Zhang, Gang, E-mail: peiqx@ihpc.a-star.edu.sg, E-mail: zhangg@ihpc.a-star.edu.sg; Zhang, Yong-Wei [Institute of High Performance Computing, A*STAR, Singapore 138632 (Singapore)

    2016-02-14

    Calculations based on the density functional theory and empirical molecular dynamics are performed to investigate interlayer interaction, electronic structure and thermal transport of a bilayer heterostructure consisting of silicene and hexagonal boron nitride (h-BN). In this heterostructure, the two layers are found to interact weakly via a non-covalent binding. As a result, the Dirac cone of silicene is preserved with the Dirac cone point being located exactly at the Fermi level, and only a small amount of electrons are transferred from h-BN to silicene, suggesting that silicene dominates the electronic transport. Molecular dynamics calculation results demonstrate that the heat current along h-BN is six times of that along silicene, suggesting that h-BN dominates the thermal transport. This decoupled role of h-BN and silicene in thermal and electronic transport suggests that the BN-silicene bilayer heterostructure is promising for thermoelectric applications.

  10. Protein Kinases C-Mediated Regulations of Drug Transporter Activity, Localization and Expression

    Directory of Open Access Journals (Sweden)

    Abdullah Mayati

    2017-04-01

    Full Text Available Drug transporters are now recognized as major actors in pharmacokinetics, involved notably in drug–drug interactions and drug adverse effects. Factors that govern their activity, localization and expression are therefore important to consider. In the present review, the implications of protein kinases C (PKCs in transporter regulations are summarized and discussed. Both solute carrier (SLC and ATP-binding cassette (ABC drug transporters can be regulated by PKCs-related signaling pathways. PKCs thus target activity, membrane localization and/or expression level of major influx and efflux drug transporters, in various normal and pathological types of cells and tissues, often in a PKC isoform-specific manner. PKCs are notably implicated in membrane insertion of bile acid transporters in liver and, in this way, are thought to contribute to cholestatic or choleretic effects of endogenous compounds or drugs. The exact clinical relevance of PKCs-related regulation of drug transporters in terms of drug resistance, pharmacokinetics, drug–drug interactions and drug toxicity remains however to be precisely determined. This issue is likely important to consider in the context of the development of new drugs targeting PKCs-mediated signaling pathways, for treating notably cancers, diabetes or psychiatric disorders.

  11. Interleukin-10 increases reverse cholesterol transport in macrophages through its bidirectional interaction with liver X receptor α

    International Nuclear Information System (INIS)

    Halvorsen, Bente; Holm, Sverre; Yndestad, Arne; Scholz, Hanne; Sagen, Ellen Lund; Nebb, Hilde; Holven, Kirsten B.; Dahl, Tuva B.; Aukrust, Pål

    2014-01-01

    Highlights: • IL-10 promotes reverse cholesterol efflux from lipid loaded macrophages. • IL-10 increases the expression of ABCA-1 and ABCG-1. • IL-10 exhibits cross-talk with the nuclear receptor LXRα. - Abstract: Interleukin (IL)-10 is a prototypical anti-inflammatory cytokine that has been shown to attenuate atherosclerosis development. In addition to its anti-inflammatory properties, the anti-atherogenic effect of IL-10 has recently also been suggested to reflect a complex effect of IL-10 on lipid metabolism in macrophages. In the present study we examined the effects of IL-10 on cholesterol efflux mechanism in lipid-loaded THP-1 macrophages. Our main findings were: (i) IL-10 significantly enhanced cholesterol efflux induced by fetal-calf serum, high-density lipoprotein (HDL) 2 and apolipoprotein A-1. (ii) The IL-10-mediated effects on cholesterol efflux were accompanied by an increased IL-10-mediated expression of the ATP-binding cassette transporters ABCA1 and ABCG1, that was further enhanced when the cells were co-activated with the liver X receptor (LXR)α agonist (22R)-hydroxycholesterol. (iii) The effect of LXRα activation on the IL-10-mediated effects on the ATP-binding cassette transporters seems to include enhancing effects on the IL-10 receptor 1 (IL10R1) expression and interaction with STAT-3 signaling. (iv) These enhancing effects on ABCA1 and ABCG1 was not seen when the cells were stimulated with the IL-10 family members IL-22 and IL-24. This study suggests that the anti-atherogenic properties of IL-10 may include enhancing effects on cholesterol efflux mechanism that involves cross-talk with LXRα activation

  12. Interleukin-10 increases reverse cholesterol transport in macrophages through its bidirectional interaction with liver X receptor α

    Energy Technology Data Exchange (ETDEWEB)

    Halvorsen, Bente, E-mail: Bente.Halvorsen@rr-research.no [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo (Norway); Holm, Sverre [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Yndestad, Arne [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo (Norway); Scholz, Hanne [Section for Transplantation, Institute for Surgical Research, Oslo University Hospital Rikshospitalet, Oslo (Norway); Sagen, Ellen Lund [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Nebb, Hilde [Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); Holven, Kirsten B. [Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Oslo (Norway); Dahl, Tuva B. [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); Aukrust, Pål [Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo (Norway); Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital Rikshospitalet, Oslo (Norway); Institute of Clinical Medicine, University of Oslo, Oslo (Norway); K.G. Jebsen Inflammation Research Center, University of Oslo, Oslo (Norway)

    2014-08-08

    Highlights: • IL-10 promotes reverse cholesterol efflux from lipid loaded macrophages. • IL-10 increases the expression of ABCA-1 and ABCG-1. • IL-10 exhibits cross-talk with the nuclear receptor LXRα. - Abstract: Interleukin (IL)-10 is a prototypical anti-inflammatory cytokine that has been shown to attenuate atherosclerosis development. In addition to its anti-inflammatory properties, the anti-atherogenic effect of IL-10 has recently also been suggested to reflect a complex effect of IL-10 on lipid metabolism in macrophages. In the present study we examined the effects of IL-10 on cholesterol efflux mechanism in lipid-loaded THP-1 macrophages. Our main findings were: (i) IL-10 significantly enhanced cholesterol efflux induced by fetal-calf serum, high-density lipoprotein (HDL){sub 2} and apolipoprotein A-1. (ii) The IL-10-mediated effects on cholesterol efflux were accompanied by an increased IL-10-mediated expression of the ATP-binding cassette transporters ABCA1 and ABCG1, that was further enhanced when the cells were co-activated with the liver X receptor (LXR)α agonist (22R)-hydroxycholesterol. (iii) The effect of LXRα activation on the IL-10-mediated effects on the ATP-binding cassette transporters seems to include enhancing effects on the IL-10 receptor 1 (IL10R1) expression and interaction with STAT-3 signaling. (iv) These enhancing effects on ABCA1 and ABCG1 was not seen when the cells were stimulated with the IL-10 family members IL-22 and IL-24. This study suggests that the anti-atherogenic properties of IL-10 may include enhancing effects on cholesterol efflux mechanism that involves cross-talk with LXRα activation.

  13. Electronic transport and lasing in microstructures

    International Nuclear Information System (INIS)

    Lax, M.

    1992-01-01

    We consider the interaction of hot carriers with hot phonons in a quantum well. Transport is considered in the transverse direction and tunneling through the well barriers. Time-dependent transport effects down to the femto-second regime are included, as are strong and/or microwave fields, with negative resistance effects. Resonant tunneling assisted by phonon relaxation and infra-red radiation will be explored. The limitations on transmission of information due to partition noise, as influenced by the design of semiconductor feedback lasers will be considered. The use of light scattering and decision theory to detect shell-like aerosols is examined

  14. Two Differential Binding Mechanisms of FG-Nucleoporins and Nuclear Transport Receptors

    Directory of Open Access Journals (Sweden)

    Piau Siong Tan

    2018-03-01

    Full Text Available Summary: Phenylalanine-glycine-rich nucleoporins (FG-Nups are intrinsically disordered proteins, constituting the selective barrier of the nuclear pore complex (NPC. Previous studies showed that nuclear transport receptors (NTRs were found to interact with FG-Nups by forming an “archetypal-fuzzy” complex through the rapid formation and breakage of interactions with many individual FG motifs. Here, we use single-molecule studies combined with atomistic simulations to show that, in sharp contrast, FG-Nup214 undergoes a coupled reconfiguration-binding mechanism when interacting with the export receptor CRM1. Association and dissociation rate constants are more than an order of magnitude lower than in the archetypal-fuzzy complex between FG-Nup153 and NTRs. Unexpectedly, this behavior appears not to be encoded selectively into CRM1 but rather into the FG-Nup214 sequence. The same distinct binding mechanisms are unperturbed in O-linked β-N-acetylglucosamine-modified FG-Nups. Our results have implications for differential roles of distinctly spatially distributed FG-Nup⋅NTR interactions in the cell. : Archetypal-fuzzy complexes found in most FG-Nucleoporin⋅nuclear transport receptor complexes allow fast yet specific nuclear transport. Tan et al. show that FG-Nup214, located at the periphery of the nuclear pore complex, binds to CRM1⋅RanGTP via a coupled reconfiguration-binding mechanism, which can enable different functionalities e.g., cargo release. Keywords: intrinsically disordered protein, glycosylation, FG-Nup, nuclear transport receptors, binding mechanism, single-molecule FRET, molecular dynamics simulations

  15. Molecular properties of mammalian proteins that interact with cGMP: protein kinases, cation channels, phosphodiesterases, and multi-drug anion transporters.

    Science.gov (United States)

    Francis, Sharron H; Blount, Mitsi A; Zoraghi, Roya; Corbin, Jackie D

    2005-09-01

    Cyclic GMP is a critical second messenger signaling molecule in many mammalian cell types. It is synthesized by a family of guanylyl cyclases that is activated in response to stimuli from hormones such as natriuretic peptides, members of the guanylin family, and chemical stimuli including nitric oxide and carbon monoxide. The resulting elevation of cGMP modulates myriad physiological processes. Three major groups of cellular proteins bind cGMP specifically at allosteric sites; interaction of cGMP with these sites modulates the activities and functions of other domains within these protein groups to bring about physiological effects. These proteins include the cyclic nucleotide (cN)-dependent protein kinases, cN-gated cation channels, and cGMP-binding phosphodiesterases (PDE). Cyclic GMP also interacts with the catalytic sites of many cN PDEs and with some members of the multi-drug anion transporter family (MRPs) which can extrude nucleotides from cells. The allosteric cN-binding sites in the kinases and the cN-gated channels are evolutionarily and biochemically related, whereas the allosteric cGMP-binding sites in PDEs (also known as GAF domains), the catalytic sites of PDEs , and the ligand-binding sites in the MRPs are evolutionarily and biochemically distinct from each other and from those in the kinase and channel families. The sites that interact with cGMP within each of these groups of proteins have unique properties that provide for cGMP binding. Within a given cell, cGMP can potentially interact with members of all these groups of proteins if they are present. The relative abundance and affinities of these various cGMP-binding sites in conjunction with their subcellular compartmentation, proximity to cyclases and PDEs, and post-translational modification contribute importantly in determining the impact of these respective proteins to cGMP signaling within a particular cell.

  16. BEAMR: An interactive graphic computer program for design of charged particle beam transport systems

    Science.gov (United States)

    Leonard, R. F.; Giamati, C. C.

    1973-01-01

    A computer program for a PDP-15 is presented which calculates, to first order, the characteristics of charged-particle beam as it is transported through a sequence of focusing and bending magnets. The maximum dimensions of the beam envelope normal to the transport system axis are continuously plotted on an oscilloscope as a function of distance along the axis. Provision is made to iterate the calculation by changing the types of magnets, their positions, and their field strengths. The program is especially useful for transport system design studies because of the ease and rapidity of altering parameters from panel switches. A typical calculation for a system with eight elements is completed in less than 10 seconds. An IBM 7094 version containing more-detailed printed output but no oscilloscope display is also presented.

  17. Enigma interacts with adaptor protein with PH and SH2 domains to control insulin-induced actin cytoskeleton remodeling and glucose transporter 4 translocation.

    Science.gov (United States)

    Barrès, Romain; Grémeaux, Thierry; Gual, Philippe; Gonzalez, Teresa; Gugenheim, Jean; Tran, Albert; Le Marchand-Brustel, Yannick; Tanti, Jean-François

    2006-11-01

    APS (adaptor protein with PH and SH2 domains) initiates a phosphatidylinositol 3-kinase-independent pathway involved in insulin-stimulated glucose transport. We recently identified Enigma, a PDZ and LIM domain-containing protein, as a partner of APS and showed that APS-Enigma complex plays a critical role in actin cytoskeleton organization in fibroblastic cells. Because actin rearrangement is important for insulin-induced glucose transporter 4 (Glut 4) translocation, we studied the potential involvement of Enigma in insulin-induced glucose transport in 3T3-L1 adipocytes. Enigma mRNA was expressed in differentiated adipocytes and APS and Enigma were colocalized with cortical actin. Expression of an APS mutant unable to bind Enigma increased the insulin-induced Glut 4 translocation to the plasma membrane. By contrast, overexpression of Enigma inhibited insulin-stimulated glucose transport and Glut 4 translocation without alterations in proximal insulin signaling. This inhibitory effect was prevented with the deletion of the LIM domains of Enigma. Using time-lapse fluorescent microscopy of green fluorescent protein-actin, we demonstrated that the overexpression of Enigma altered insulin-induced actin rearrangements, whereas the expression of Enigma without its LIM domains was without effect. A physiological link between increased expression of Enigma and an alteration in insulin-induced glucose uptake was suggested by the increase in Enigma mRNA expression in adipose tissue of diabetic obese patients. Taken together, these data strongly suggest that the interaction between APS and Enigma is involved in insulin-induced Glut 4 translocation by regulating cortical actin remodeling and raise the possibility that modification of APS/Enigma ratio could participate in the alteration of insulin-induced glucose uptake in adipose tissue.

  18. Drug interactions at the human placenta: what is the evidence?

    Directory of Open Access Journals (Sweden)

    Miriam eRubinchik-Stern

    2012-07-01

    Full Text Available Pregnant women (and their fetuses are treated with a significant number of prescription and nonprescription medications. Interactions among those drugs may affect their efficacy and toxicity in both mother and fetus. Whereas interactions that result in altered drug concentrations in maternal plasma are detectable, those involving modulation of placental transfer mechanisms are rarely reflected by altered drug concentrations in maternal plasma. Therefore, they are often overlooked. Placental-mediated interactions are possible because the placenta is not only a passive diffusional barrier, but also expresses a variety of influx and efflux transporters and drug metabolizing enzymes. Current data on placental-mediated drug interactions are limited. In rodents, pharmacological or genetic manipulations of placental transporters significantly affect fetal drug exposure. In contrast, studies in human placentae suggest that the magnitude of such interactions is modest in most cases. Nevertheless, under certain circumstances, such interactions may be of clinical significance. This review describes currently known mechanisms of placental-mediated drug interactions and the potential implications of such interactions in humans. Better understanding of those mechanisms is important for minimizing fetal toxicity from drugs while improving their efficacy when directed to treat the fetus.

  19. Perturbative analysis of transport and fluctuation studies on RFX

    International Nuclear Information System (INIS)

    Martini, S.

    2002-01-01

    On the RFX reversed field pinch different transport mechanisms govern the centre and the edge of the plasma. Core transport is driven by parallel transport in a stochastic magnetic field, giving rise to an outward directed particle convection velocity. At the edge, roughly corresponding to the region outside the toroidal field reversal surface (where q=0), electrostatic fluctuations are an important loss channel, but more than 50% of the power losses have been associated to localized plasma-wall interaction due to the non-axisymmetric magnetic perturbations caused by locked modes. In the paper we present the most recent progress made in the modeling and understanding of the above mechanisms underlying particle and energy transport. The paper also discusses the correlations between core and edge transport phenomena. The main tools are perturbative transport studies by pellet injection and the analysis of the contribution of intermittency processes to particle transport in the edge. (author)

  20. Aeolian sediment transport on a beach: Surface moisture, wind fetch, and mean transport

    Science.gov (United States)

    Bauer, B. O.; Davidson-Arnott, R. G. D.; Hesp, P. A.; Namikas, S. L.; Ollerhead, J.; Walker, I. J.

    2009-04-01

    Temporal and spatial changes in wind speed, wind direction, and moisture content are ubiquitous across sandy coastal beaches. Often these factors interact in unknown ways to create complexity that confounds our ability to model sediment transport at any point across the beach as well as our capacity to predict sediment delivery into the adjacent foredunes. This study was designed to measure wind flow and sediment transport over a beach and foredune at Greenwich Dunes, Prince Edward Island National Park, with the express purpose of addressing these complex interactions. Detailed measurements are reported for one stormy day, October 11, 2004, during which meteorological conditions were highly variable. Wind speed ranged from 4 ms - 1 to over 20 ms - 1 , wind direction was highly oblique varying between 60° and 85° from shore perpendicular, and moisture content of the sand surface ranged from a minimum of about 3% (by mass) to complete saturation depending on precipitation, tidal excursion, and storm surge that progressively inundated the beach. The data indicate that short-term variations (i.e., minutes to hours) in sediment transport across this beach arise predominantly because of short-term changes in wind speed, as is expected, but also because of variations in wind direction, precipitation intensity, and tide level. Even slight increases in wind speed are capable of driving more intense saltation events, but this relationship is mediated by other factors on this characteristically narrow beach. As the angle of wind approach becomes more oblique, the fetch distance increases and allows greater opportunity for the saltation system to evolve toward an equilibrium transport state before reaching the foredunes. Whether the theoretically-predicted maximum rate of transport is ever achieved depends on the character of the sand surface (e.g., grain size, slope, roughness, vegetation, moisture content) and on various attributes of the wind field (e.g., average wind

  1. Discrete element modelling of bedload transport

    Science.gov (United States)

    Loyer, A.; Frey, P.

    2011-12-01

    Discrete element modelling (DEM) has been widely used in solid mechanics and in granular physics. In this type of modelling, each individual particle is taken into account and intergranular interactions are modelled with simple laws (e.g. Coulomb friction). Gravity and contact forces permit to solve the dynamical behaviour of the system. DEM is interesting to model configurations and access to parameters not directly available in laboratory experimentation, hence the term "numerical experimentations" sometimes used to describe DEM. DEM was used to model bedload transport experiments performed at the particle scale with spherical glass beads in a steep and narrow flume. Bedload is the larger material that is transported on the bed on stream channels. It has a great geomorphic impact. Physical processes ruling bedload transport and more generally coarse-particle/fluid systems are poorly known, arguably because granular interactions have been somewhat neglected. An existing DEM code (PFC3D) already computing granular interactions was used. We implemented basic hydrodynamic forces to model the fluid interactions (buoyancy, drag, lift). The idea was to use the minimum number of ingredients to match the experimental results. Experiments were performed with one-size and two-size mixtures of coarse spherical glass beads entrained by a shallow turbulent and supercritical water flow down a steep channel with a mobile bed. The particle diameters were 4 and 6mm, the channel width 6.5mm (about the same width as the coarser particles) and the channel inclination was typically 10%. The water flow rate and the particle rate were kept constant at the upstream entrance and adjusted to obtain bedload transport equilibrium. Flows were filmed from the side by a high-speed camera. Using image processing algorithms made it possible to determine the position, velocity and trajectory of both smaller and coarser particles. Modelled and experimental particle velocity and concentration depth

  2. On the Acceleration and Transport of Electrons Generated by Intense Laser-Plasma Interactions at Sharp Interfaces

    Science.gov (United States)

    May, Joshua Joseph

    The continued development of the chirped pulse amplification technique has allowed for the development of lasers with powers of in excess of 10 15W, for pulse lengths with durations of between .01 and 10 picoseconds, and which can be focused to energy densities greater than 100 giga-atmospheres. When such lasers are focused onto material targets, the possibility of creating particle beams with energy fluxes of comparable parameters arises. Such interactions have a number of theorized applications. For instance, in the Fast Ignition concept for Inertial Confinement Fusion [1], a high-intensity laser efficiently transfers its energy into an electron beam with an appropriate spectra which is then transported into a compressed target and initiate a fusion reaction. Another possible use is the so called Radiation Pressure Acceleration mechanism, in which a high-intensity, circularly polarized laser is used to create a mono-energetic ion beam which could then be used for medical imaging and treatment, among other applications. For this latter application, it is important that the laser energy is transferred to the ions and not to the electrons. However the physics of such high energy-density laser-matter interactions is highly kinetic and non-linear, and presently not fully understood. In this dissertation, we use the Particle-in-Cell code OSIRIS [2, 3] to explore the generation and transport of relativistic particle beams created by high intensity lasers focused onto solid density matter at normal incidence. To explore the generation of relativistic electrons by such interactions, we use primarily one-dimensional (1D) and two-dimensional (2D), and a few three-dimensional simulations (3D). We initially examine the idealized case of normal incidence of relatively short, plane-wave lasers on flat, sharp interfaces. We find that in 1D the results are highly dependent on the initial temperature of the plasma, with significant absorption into relativistic electrons only

  3. Transport of Organic Solutes in Clay Formations

    Science.gov (United States)

    The research is a pilot investigation for the SERDP (Strategic Environmental Research and Development Program, DoD) founded project, Impact of Clay-DNAPL Interactions on Transport and Storage of Chlorinated Solvents in Low Permeability Zones, from 2010-2012. The report tries to s...

  4. Plasticity of an ultrafast interaction between nucleoporins and nuclear transport receptors.

    Science.gov (United States)

    Milles, Sigrid; Mercadante, Davide; Aramburu, Iker Valle; Jensen, Malene Ringkjøbing; Banterle, Niccolò; Koehler, Christine; Tyagi, Swati; Clarke, Jane; Shammas, Sarah L; Blackledge, Martin; Gräter, Frauke; Lemke, Edward A

    2015-10-22

    The mechanisms by which intrinsically disordered proteins engage in rapid and highly selective binding is a subject of considerable interest and represents a central paradigm to nuclear pore complex (NPC) function, where nuclear transport receptors (NTRs) move through the NPC by binding disordered phenylalanine-glycine-rich nucleoporins (FG-Nups). Combining single-molecule fluorescence, molecular simulations, and nuclear magnetic resonance, we show that a rapidly fluctuating FG-Nup populates an ensemble of conformations that are prone to bind NTRs with near diffusion-limited on rates, as shown by stopped-flow kinetic measurements. This is achieved using multiple, minimalistic, low-affinity binding motifs that are in rapid exchange when engaging with the NTR, allowing the FG-Nup to maintain an unexpectedly high plasticity in its bound state. We propose that these exceptional physical characteristics enable a rapid and specific transport mechanism in the physiological context, a notion supported by single molecule in-cell assays on intact NPCs. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  5. Interaction between serotonin transporter and serotonin receptor 1 B genes polymorphisms may be associated with antisocial alcoholism.

    Science.gov (United States)

    Wang, Tzu-Yun; Lee, Sheng-Yu; Chen, Shiou-Lan; Chang, Yun-Hsuan; Chen, Shih-Heng; Chu, Chun-Hsien; Huang, San-Yuan; Tzeng, Nian-Sheng; Wang, Chen-Lin; Lee, I Hui; Yeh, Tzung Lieh; Yang, Yen Kuang; Lu, Ru-Band

    2012-07-11

    Several studies have hypothesized that genes regulating the components of the serotonin system, including serotonin transporter (5-HTTLPR) and serotonin 1 B receptor (5-HT1B), may be associated with alcoholism, but their results are contradictory because of alcoholism's heterogeneity. Therefore, we examined whether the 5-HTTLPR gene and 5-HT1B gene G861C polymorphism are susceptibility factors for a specific subtype of alcoholism, antisocial alcoholism in Han Chinese in Taiwan. We recruited 273 Han Chinese male inmates with antisocial personality disorder (ASPD) [antisocial alcoholism (AS-ALC) group (n=120) and antisocial non-alcoholism (AS-N-ALC) group (n=153)] and 191 healthy male controls from the community. Genotyping was done using PCR-RFLP. There were no significant differences in the genotypic frequency of the 5-HT1B G861C polymorphism between the 3 groups. Although AS-ALC group members more frequently carried the 5-HTTLPR S/S, S/LG, and LG/LG genotypes than controls, the difference became non-significant after controlling for the covarying effects of age. However, the 5-HTTLPR S/S, S/LG, and LG/LG genotypes may have interacted with the 5-HT1B G861C C/C polymorphism and increased the risk of becoming antisocial alcoholism. Our study suggests that neither the 5-HTTLPR gene nor the 5-HT1B G861C polymorphism alone is a risk factor for antisocial alcoholism in Taiwan's Han Chinese population, but that the interaction between both genes may increase susceptibility to antisocial alcoholism.

  6. Several hPepT1-transported drugs are substrates of the Escherichia coli proton-coupled oligopeptide transporter YdgR.

    Science.gov (United States)

    Prabhala, Bala K; Aduri, Nanda G; Iqbal, Mazhar; Rahman, Moazur; Gajhede, Michael; Hansen, Paul R; Mirza, Osman

    2017-06-01

    Proton-dependent oligopeptide transporters (POTs) are secondary active transporters found in all kingdoms of life. POTs utilize the proton electrochemical gradient for the uptake of nutrient dipeptides and tripeptides. The human POT hPepT1 is known to transport a number of drugs. As part of ongoing studies on substrate specificities of POTs from Escherichia coli, our aim in this study was to investigate whether bacterial POTs could also transport these drugs. For this, we selected the common orally administered drugs sulpiride, bestatin, valacyclovir, ampicillin and oseltamivir, that are all transported by hPepT1. The transport of these drugs was evaluated using the prototypical POT YdgR from E. coli. The transport studies were pursued through combining cell-based assays with liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. These investigations revealed that YdgR from E. coli is able to transport five (sulpiride, bestatin, valacyclovir, ampicillin and oseltamivir) drugs. Furthermore, cells not overexpressing YdgR were also able to transport these drugs in a POT-like manner. Orthologues of YdgR are found in several species in the gut microbiome; hence, our findings could have implications for further understanding about the interaction between gut microbes and orally administered drugs. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  7. Experimental investigation of the impact of compound-specific dispersion and electrostatic interactions on transient transport and solute breakthrough

    Science.gov (United States)

    Muniruzzaman, Muhammad; Rolle, Massimo

    2017-02-01

    This study investigates the effects of compound-specific diffusion/dispersion and electrochemical migration on transient solute transport in saturated porous media. We conducted laboratory bench-scale experiments, under advection-dominated regimes (seepage velocity: 0.5, 5, 25 m/d), in a quasi two-dimensional flow-through setup using pulse injection of multiple tracers (both uncharged and ionic species). Extensive sampling and measurement of solutes' concentrations (˜1500 samples; >3000 measurements) were performed at the outlet of the flow-through setup, at high spatial and temporal resolution. The experimental results show that compound-specific effects and charge-induced Coulombic interactions are important not only at low velocities and/or for steady state plumes but also for transient transport under high flow velocities. Such effects can lead to a remarkably different behavior of measured breakthrough curves also at very high Péclet numbers. To quantitatively interpret the experimental results, we used four modeling approaches: classical advection-dispersion equation (ADE), continuous time random walk (CTRW), dual-domain mass transfer model (DDMT), and a multicomponent ionic dispersion model. The latter is based on the multicomponent formulation of coupled diffusive/dispersive fluxes and was used to describe and explain the electrostatic effects of charged species. Furthermore, we determined experimentally the temporal profiles of the flux-related dilution index. This metric of mixing, used in connection with the traditional solute breakthrough curves, proved to be useful to correctly distinguish between plume spreading and mixing, particularly for the cases in which the sole analysis of integrated concentration breakthrough curves may lead to erroneous interpretation of plume dilution.

  8. Dynamics of indirect exciton transport by moving acoustic fields

    International Nuclear Information System (INIS)

    Violante, A; Lazić, S; Hey, R; Santos, P V; Cohen, K; Rapaport, R

    2014-01-01

    We report on the modulation of indirect excitons (IXs) as well as their transport by moving periodic potentials produced by surface acoustic waves (SAWs). The potential modulation induced by the SAW strain modifies both the band gap and the electrostatic field in the quantum wells confining the IXs, leading to changes in their energy. In addition, this potential captures and transports IXs over several hundreds of μm. While the IX packets keep to a great extent their spatial shape during transport by the moving potential, the effective transport velocity is lower than the SAW group velocity and increases with the SAW amplitude. This behavior is attributed to the capture of IXs by traps along the transport path, thereby increasing the IX transit time. The experimental results are well-reproduced by an analytical model for the interaction between trapping centers and IXs during transport. (paper)

  9. Heat transport in the XXZ spin chain: from ballistic to diffusive regimes and dephasing enhancement

    International Nuclear Information System (INIS)

    Mendoza-Arenas, J J; Al-Assam, S; Clark, S R; Jaksch, D

    2013-01-01

    In this work we study the heat transport in an XXZ spin-1/2 Heisenberg chain with homogeneous magnetic field, incoherently driven out of equilibrium by reservoirs at the boundaries. We focus on the effect of bulk dephasing (energy-dissipative) processes in different parameter regimes of the system. The non-equilibrium steady state of the chain is obtained by simulating its evolution under the corresponding Lindblad master equation, using the time evolving block decimation method. In the absence of dephasing, the heat transport is ballistic for weak interactions, while being diffusive in the strongly interacting regime, as evidenced by the heat current scaling with the system size. When bulk dephasing takes place in the system, diffusive transport is induced in the weakly interacting regime, with the heat current monotonically decreasing with the dephasing rate. In contrast, in the strongly interacting regime, the heat current can be significantly enhanced by dephasing for systems of small size. (paper)

  10. CHMTRNS, Non-Equilibrium Chemical Transport Code

    International Nuclear Information System (INIS)

    Noorishad, J.; Carnahan, C.L.; Benson, L.V.

    1998-01-01

    1 - Description of program or function: CHMTRNS simulates solute transport for steady one-dimensional fluid flow by convection and diffusion or dispersion in a saturated porous medium based on the assumption of local chemical equilibrium. The chemical interactions included in the model are aqueous-phase complexation, solid-phase ion exchange of bare ions and complexes using the surface complexation model, and precipitation or dissolution of solids. The program can simulate the kinetic dissolution or precipitation for calcite and silica as well as irreversible dissolution of glass. Thermodynamic parameters are temperature dependent and are coupled to a companion heat transport simulator; thus, the effects of transient temperature conditions can be considered. Options for oxidation-reduction (redox) and C-13 fractionation as well as non-isothermal conditions are included. 2 - Method of solution: The governing equations for both reactive chemical and heat transport are discretized in time and space. For heat transport, the Crank-Nicolson approximation is used in conjunction with a LU decomposition and backward substitution solution procedure. To deal with the strong nonlinearity of the chemical transport equations, a generalized Newton-Raphson method is used

  11. Colloid-Facilitated Transport of Radionuclides through the Vadose Zone

    International Nuclear Information System (INIS)

    Flury, Markus; Harsh, James B.; Zachara, John M.; McCarthy, John F.; Lichtner, Peter C.

    2006-01-01

    This project seeks to improve the basic understanding of the role of colloids in facilitating the transport of contaminants in the vadose zone. We focus on three major thrusts: (1) thermodynamic stability and mobility of colloids formed by reactions of sediments with highly alkaline tank waste solutions, (2) colloid-contaminant interactions, and (3) in-situ colloid mobilization and colloid facilitated contaminant transport occurring in both contaminated and uncontaminated Hanford sediments

  12. From conservative to reactive transport under diffusion-controlled conditions

    Science.gov (United States)

    Babey, Tristan; de Dreuzy, Jean-Raynald; Ginn, Timothy R.

    2016-05-01

    We assess the possibility to use conservative transport information, such as that contained in transit time distributions, breakthrough curves and tracer tests, to predict nonlinear fluid-rock interactions in fracture/matrix or mobile/immobile conditions. Reference simulated data are given by conservative and reactive transport simulations in several diffusive porosity structures differing by their topological organization. Reactions includes nonlinear kinetically controlled dissolution and desorption. Effective Multi-Rate Mass Transfer models (MRMT) are calibrated solely on conservative transport information without pore topology information and provide concentration distributions on which effective reaction rates are estimated. Reference simulated reaction rates and effective reaction rates evaluated by MRMT are compared, as well as characteristic desorption and dissolution times. Although not exactly equal, these indicators remain very close whatever the porous structure, differing at most by 0.6% and 10% for desorption and dissolution. At early times, this close agreement arises from the fine characterization of the diffusive porosity close to the mobile zone that controls fast mobile-diffusive exchanges. At intermediate to late times, concentration gradients are strongly reduced by diffusion, and reactivity can be captured by a very limited number of rates. We conclude that effective models calibrated solely on conservative transport information like MRMT can accurately estimate monocomponent kinetically controlled nonlinear fluid-rock interactions. Their relevance might extend to more advanced biogeochemical reactions because of the good characterization of conservative concentration distributions, even by parsimonious models (e.g., MRMT with 3-5 rates). We propose a methodology to estimate reactive transport from conservative transport in mobile-immobile conditions.

  13. Study of thermodynamic and transport properties of strongly interacting matter in a color string percolation model at RHIC

    International Nuclear Information System (INIS)

    Sahoo, Pragati; Tiwari, Swatantra Kumar; De, Sudipan; Sahoo, Raghunath

    2017-01-01

    The main perspectives of Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory are to study the properties of the strongly interacting matter and to explore the conjectured Quantum Chromodynamics (QCD) phase diagram. Lattice QCD (lQCD) predicts a smooth crossover at vanishing baryon chemical potential (μ B ) and other QCD based theoretical models predicts first order phase transition at large μB. Searching of the Critical Point in the QCD phase diagram, finding the evidence and nature of phase transition, studying the properties of the matter formed in nuclear collisions as a function of √sNN are the main goals of RHIC. To investigate the nature of the matter produced at heavy-ion collisions, the thermodynamical and transport quantities like: energy density, shear viscosity etc. are studied. It is expected that the ratio of shear viscosity (η) to entropy density (s) would exhibit a minimum value near the QCD critical point

  14. Transport and attenuation of radiations

    CERN Document Server

    Nimal, J C

    2003-01-01

    This article treats of the calculation methods used for the dimensioning of the protections against radiations. The method consists in determining for a given point the flux of particles coming from a source at a given time. A strong attenuation (of about some few mu Sv.h sup - sup 1) is in general expected between the source and the areas accessible to the personnel or the public. The calculation has to take into account a huge number of radiation-matter interactions and to solve the integral-differential transport equation which links the particles flux to the source. Several methods exist from the simplified physical model with numerical developments to the more or less precise resolution of the transport equation. These methods allows also the calculation of the uncertainties of equivalent dose rates, heat sources, structure damages using the data covariances (efficient cross-sections, modeling, etc..): 1 - transport equation; 2 - Monte-Carlo method; 3 - semi-numerical methods S sub N; 4 - methods based o...

  15. Transport and turbulence in a magnetized plasma (application to tokamak plasmas); Transport et turbulence dans un plasma magnetise (application aux plasmas de tokamaks)

    Energy Technology Data Exchange (ETDEWEB)

    Sarazin, Y

    2004-03-01

    This document gathers the lectures made in the framework of a Ph.D level physics class dedicated to plasma physics. This course is made up of 3 parts : 1) collisions and transport, 2) transport and turbulence, and 3) study of a few exchange instabilities. More precisely the first part deals with the following issues: thermonuclear fusion, Coulomb collisions, particles trajectories in a tokamak, neo-classical transport in tokamaks, the bootstrap current, and ware pinch. The second part involves: particle transport in tokamaks, quasi-linear transport, resonance islands, resonance in tokamaks, from quasi to non-linear transport, and non-linear saturation of turbulence. The third part deals with: shift velocities in fluid theory, a model for inter-change instabilities, Rayleigh-Benard instability, Hasegawa-Wakatani model, and Hasegawa-Mima model. This document ends with a series of appendices dealing with: particle-wave interaction, determination of the curvature parameter G, Rossby waves.

  16. Energetics of Transport through the Nuclear Pore Complex.

    Directory of Open Access Journals (Sweden)

    Ali Ghavami

    Full Text Available Molecular transport across the nuclear envelope in eukaryotic cells is solely controlled by the nuclear pore complex (NPC. The NPC provides two types of nucleocytoplasmic transport: passive diffusion of small molecules and active chaperon-mediated translocation of large molecules. It has been shown that the interaction between intrinsically disordered proteins that line the central channel of the NPC and the transporting cargoes is the determining factor, but the exact mechanism of transport is yet unknown. Here, we use coarse-grained molecular dynamics simulations to quantify the energy barrier that has to be overcome for molecules to pass through the NPC. We focus on two aspects of transport. First, the passive transport of model cargo molecules with different sizes is studied and the size selectivity feature of the NPC is investigated. Our results show that the transport probability of cargoes is significantly reduced when they are larger than ∼5 nm in diameter. Secondly, we show that incorporating hydrophobic binding spots on the surface of the cargo effectively decreases the energy barrier of the pore. Finally, a simple transport model is proposed which characterizes the energy barrier of the NPC as a function of diameter and hydrophobicity of the transporting particles.

  17. Forecasting transportation impacts upon land use

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, P F [ed.

    1976-01-01

    Chapter titles include: introduction and overview; national and regional econometric models; growth and change in the Georgia regional economies; a Delphi approach to land use forecasting; land suitability and land use analysis; the interaction of transportation and land use; and, summary and conclusions. Lists of tables and figures are also included. (JGB)

  18. Transport properties for some atom-ion interactions in air

    International Nuclear Information System (INIS)

    Biolsi, L.; Holland, P.M.; Procter and Gamble Co., Cincinnati, OH)

    1985-01-01

    The thermal conductivity and viscosity for the N-N(+) and O-O(+) interactions have been calculated, using the kinetic theory of gases, from 500 K-20,000 K. Accurate spectroscopically determined potentials have been used for the calculations. The results are compared with previous results obtained using less accurate potentials. 62 references

  19. Universal interaction-driven gap in metallic carbon nanotubes

    Science.gov (United States)

    Senger, Mitchell J.; McCulley, Daniel R.; Lotfizadeh, Neda; Deshpande, Vikram V.; Minot, Ethan D.

    2018-02-01

    Suspended metallic carbon nanotubes (m-CNTs) exhibit a remarkably large transport gap that can exceed 100 meV. Both experiment and theory suggest that strong electron-electron interactions play a crucial role in generating this electronic structure. To further understand this strongly interacting system, we have performed electronic measurements of suspended m-CNTs with known diameter and chiral angle. Spectrally resolved photocurrent microscopy was used to determine m-CNT structure. The room-temperature electrical characteristics of 18 individually contacted m-CNTs were compared to their respective diameter and chiral angle. At the charge neutrality point, we observe a peak in m-CNT resistance that scales exponentially with inverse diameter. Using a thermally activated transport model, we estimate that the transport gap is (450 meV nm)/D , where D is CNT diameter. We find no correlation between the gap and the CNT chiral angle. Our results add important constraints to theories attempting to describe the electronic structure of m-CNTs.

  20. Integrated design for space transportation system

    CERN Document Server

    Suresh, B N

    2015-01-01

    The book addresses the overall integrated design aspects of a space transportation system involving several disciplines like propulsion, vehicle structures, aerodynamics, flight mechanics, navigation, guidance and control systems, stage auxiliary systems, thermal systems etc. and discusses the system approach for design, trade off analysis, system life cycle considerations, important aspects in mission management, the risk assessment, etc. There are several books authored to describe the design aspects of various areas, viz., propulsion, aerodynamics, structures, control, etc., but there is no book which presents space transportation system (STS) design in an integrated manner. This book attempts to fill this gap by addressing systems approach for STS design, highlighting the integrated design aspects, interactions between various subsystems and interdependencies. The main focus is towards the complex integrated design to arrive at an optimum, robust and cost effective space transportation system. The orbit...

  1. Competent authority regulatory control of the transport of radioactive material

    International Nuclear Information System (INIS)

    1987-04-01

    The purpose of this guide is to assist competent authorities in regulating the transport of radioactive materials and to assist users of transport regulations in their interactions with competent authorities. The guide should assist specifically those countries which are establishing their regulatory framework and further assist countries with established procedures to harmonize their application and implementation of the IAEA Regulations. This guide specifically covers various aspects of the competent authority implementation of the IAEA Regulations for the Safe Transport of Radioactive Material. In addition, physical protection and safeguards control of the transport of nuclear materials as well as third party liability aspects are briefly discussed. This is because they have to be taken into account in overall transport regulatory activities, especially when establishing the regulatory framework

  2. Distinct Mechanisms of Recognizing Endosomal Sorting Complex Required for Transport III (ESCRT-III) Protein IST1 by Different Microtubule Interacting and Trafficking (MIT) Domains*

    Science.gov (United States)

    Guo, Emily Z.; Xu, Zhaohui

    2015-01-01

    The endosomal sorting complex required for transport (ESCRT) machinery is responsible for membrane remodeling in a number of biological processes including multivesicular body biogenesis, cytokinesis, and enveloped virus budding. In mammalian cells, efficient abscission during cytokinesis requires proper function of the ESCRT-III protein IST1, which binds to the microtubule interacting and trafficking (MIT) domains of VPS4, LIP5, and Spartin via its C-terminal MIT-interacting motif (MIM). Here, we studied the molecular interactions between IST1 and the three MIT domain-containing proteins to understand the structural basis that governs pairwise MIT-MIM interaction. Crystal structures of the three molecular complexes revealed that IST1 binds to the MIT domains of VPS4, LIP5, and Spartin using two different mechanisms (MIM1 mode versus MIM3 mode). Structural comparison revealed that structural features in both MIT and MIM contribute to determine the specific binding mechanism. Within the IST1 MIM sequence, two phenylalanine residues were shown to be important in discriminating MIM1 versus MIM3 binding. These observations enabled us to deduce a preliminary binding code, which we applied to provide CHMP2A, a protein that normally only binds the MIT domain in the MIM1 mode, the additional ability to bind the MIT domain of Spartin in the MIM3 mode. PMID:25657007

  3. Distinct mechanisms of recognizing endosomal sorting complex required for transport III (ESCRT-III) protein IST1 by different microtubule interacting and trafficking (MIT) domains.

    Science.gov (United States)

    Guo, Emily Z; Xu, Zhaohui

    2015-03-27

    The endosomal sorting complex required for transport (ESCRT) machinery is responsible for membrane remodeling in a number of biological processes including multivesicular body biogenesis, cytokinesis, and enveloped virus budding. In mammalian cells, efficient abscission during cytokinesis requires proper function of the ESCRT-III protein IST1, which binds to the microtubule interacting and trafficking (MIT) domains of VPS4, LIP5, and Spartin via its C-terminal MIT-interacting motif (MIM). Here, we studied the molecular interactions between IST1 and the three MIT domain-containing proteins to understand the structural basis that governs pairwise MIT-MIM interaction. Crystal structures of the three molecular complexes revealed that IST1 binds to the MIT domains of VPS4, LIP5, and Spartin using two different mechanisms (MIM1 mode versus MIM3 mode). Structural comparison revealed that structural features in both MIT and MIM contribute to determine the specific binding mechanism. Within the IST1 MIM sequence, two phenylalanine residues were shown to be important in discriminating MIM1 versus MIM3 binding. These observations enabled us to deduce a preliminary binding code, which we applied to provide CHMP2A, a protein that normally only binds the MIT domain in the MIM1 mode, the additional ability to bind the MIT domain of Spartin in the MIM3 mode. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Molecular determinants of transport stimulation of EAAT2 are located at interface between the trimerization and substrate transport domains.

    Science.gov (United States)

    Mortensen, Ole V; Liberato, José L; Coutinho-Netto, Joaquim; Dos Santos, Wagner F; Fontana, Andréia C K

    2015-04-01

    Excitatory amino acid transporters (EAATs) regulate glutamatergic signal transmission by clearing extracellular glutamate. Dysfunction of these transporters has been implicated in the pathogenesis of various neurological disorders. Previous studies have shown that venom from the spider Parawixia bistriata and a purified compound (Parawixin1) stimulate EAAT2 activity and protect retinal tissue from ischemic damage. In the present study, the EAAT2 subtype specificity of this compound was explored, employing chimeric proteins between EAAT2 and EAAT3 transporter subtypes and mutants to characterize the structural region targeted by the compound. This identified a critical residue (Histidine-71 in EAAT2 and Serine-45 in EAAT3) in transmembrane domain 2 (TM2) to be important for the selectivity between EAAT2 and EAAT3 and for the activity of the venom. Using the identified residue in TM2 as a structural anchor, several neighboring amino acids within TM5 and TM8 were identified to also be important for the activity of the venom. This structural domain of the transporter lies at the interface of the rigid trimerization domain and the central substrate-binding transport domain. Our studies suggest that the mechanism of glutamate transport enhancement involves an interaction with the transporter that facilitates the movement of the transport domain. We identified a domain (purple star) in the glutamate transporter EAAT2 that is important for transport stimulation through a spider venom, and suggest a mechanism for enhanced transporter function through facilitated substrate translocation (arrow). Because the dysfunction of glutamate transporters is implicated in the pathogenesis of neurological disorders, understanding the mechanisms of enhanced transport could have therapeutic implications. © 2015 International Society for Neurochemistry.

  5. Charge transport through DNA based electronic barriers

    Science.gov (United States)

    Patil, Sunil R.; Chawda, Vivek; Qi, Jianqing; Anantram, M. P.; Sinha, Niraj

    2018-05-01

    We report charge transport in electronic 'barriers' constructed by sequence engineering in DNA. Considering the ionization potentials of Thymine-Adenine (AT) and Guanine-Cytosine (GC) base pairs, we treat AT as 'barriers'. The effect of DNA conformation (A and B form) on charge transport is also investigated. Particularly, the effect of width of 'barriers' on hole transport is investigated. Density functional theory (DFT) calculations are performed on energy minimized DNA structures to obtain the electronic Hamiltonian. The quantum transport calculations are performed using the Landauer-Buttiker framework. Our main findings are contrary to previous studies. We find that a longer A-DNA with more AT base pairs can conduct better than shorter A-DNA with a smaller number of AT base pairs. We also find that some sequences of A-DNA can conduct better than a corresponding B-DNA with the same sequence. The counterions mediated charge transport and long range interactions are speculated to be responsible for counter-intuitive length and AT content dependence of conductance of A-DNA.

  6. Thermodynamics of competitive molecular channel transport: application to artificial nuclear pores.

    Directory of Open Access Journals (Sweden)

    Wolfgang R Bauer

    Full Text Available In an analytical model channel transport is analyzed as a function of key parameters, determining efficiency and selectivity of particle transport in a competitive molecular environment. These key parameters are the concentration of particles, solvent-channel exchange dynamics, as well as particle-in-channel- and interparticle interaction. These parameters are explicitly related to translocation dynamics and channel occupation probability. Slowing down the exchange dynamics at the channel ends, or elevating the particle concentration reduces the in-channel binding strength necessary to maintain maximum transport. Optimized in-channel interaction may even shift from binding to repulsion. A simple equation gives the interrelation of access dynamics and concentration at this transition point. The model is readily transferred to competitive transport of different species, each of them having their individual in-channel affinity. Combinations of channel affinities are determined which differentially favor selectivity of certain species on the cost of others. Selectivity for a species increases if its in-channel binding enhances the species' translocation probability when compared to that of the other species. Selectivity increases particularly for a wide binding site, long channels, and fast access dynamics. Recent experiments on competitive transport of in-channel binding and inert molecules through artificial nuclear pores serve as a paradigm for our model. It explains qualitatively and quantitatively how binding molecules are favored for transport at the cost of the transport of inert molecules.

  7. Transport of Mineral Dust and Its Impact on Climate

    Directory of Open Access Journals (Sweden)

    Kerstin Schepanski

    2018-04-01

    Full Text Available Mineral dust plays a pivotal role in the Earth’s system. Dust modulates the global energy budget directly via its interactions with radiation and indirectly via its influence on cloud and precipitation formation processes. Dust is a micro-nutrient and fertilizer for ecosystems due to its mineralogical composition and thus impacts on the global carbon cycle. Hence, dust aerosol is an essential part of weather and climate. Dust suspended in the air is determined by the atmospheric dust cycle: Dust sources and emission processes define the amount of dust entrained into the atmosphere. Atmospheric mixing and circulation carry plumes of dust to remote places. Ultimately, dust particles are removed from the atmosphere by deposition processes such as gravitational settling and rain wash out. During its residence time, dust interacts with and thus modulates the atmosphere resulting into changes such as in surface temperature, wind, clouds, and precipitation rates. There are still uncertainties regarding individual dust interactions and their relevance. Dust modulates key processes that are inevitably influencing the Earth energy budget. Dust transport allows for these interactions and at the same time, the intermittency of dust transport introduces additional fluctuations into a complex and challenging system.

  8. Spin Transport in Semiconductor heterostructures

    International Nuclear Information System (INIS)

    Marinescu, Domnita Catalina

    2011-01-01

    The focus of the research performed under this grant has been the investigation of spin transport in magnetic semiconductor heterostructures. The interest in these systems is motivated both by their intriguing physical properties, as the physical embodiment of a spin-polarized Fermi liquid, as well as by their potential applications as spintronics devices. In our work we have analyzed several different problems that affect the spin dynamics in single and bi-layer spin-polarized two-dimensional (2D) systems. The topics of interests ranged from the fundamental aspects of the electron-electron interactions, to collective spin and charge density excitations and spin transport in the presence of the spin-orbit coupling. The common denominator of these subjects is the impact at the macroscopic scale of the spin-dependent electron-electron interaction, which plays a much more subtle role than in unpolarized electron systems. Our calculations of several measurable parameters, such as the excitation frequencies of magneto-plasma modes, the spin mass, and the spin transresistivity, propose realistic theoretical estimates of the opposite-spin many-body effects, in particular opposite-spin correlations, that can be directly connected with experimental measurements.

  9. Study on the Relationship between Land Transport and Economic Growth in Xinjiang

    Directory of Open Access Journals (Sweden)

    Jingxin Sun

    2018-01-01

    Full Text Available Xinjiang’s land transport network is mainly comprised of highways and railways. Using statistical data from 1985 to 2015, this study applies the Lotka-Volterra model to investigate the competitive interactions among highway transport, railway transport, and the regional economy of Xinjiang. We can draw the following conclusions: First, highway mileage, highway passenger transportation, and railway freight transportation have played a significant role in promoting the development of the national economy in Xinjiang, while the latter has weakened highway passenger transportation and promoted the growth of the added value of transportation industry (AVTI, railway mileage, and railway passenger transportation. Second, highway passenger transportation enhances the development of railway passenger transportation, while railway freight transportation has played the same role in the development of highway freight transportation. Third, the increase in AVTI will increase total population, but both may have a negative impact on the national economy in the short term. Fourth, there is no significant relationship between the economy and transportation investment.

  10. Tissue-specific amino acid transporter partners ACE2 and collectrin differentially interact with hartnup mutations

    DEFF Research Database (Denmark)

    Camargo, Simone M R; Singer, Dustin; Makrides, Victoria

    2008-01-01

    BACKGROUND & AIMS: Hartnup amino acid transporter B(0)AT1 (SLC6A19) is the major luminal sodium-dependent neutral amino acid transporter of small intestine and kidney proximal tubule. The expression of B(0)AT1 in kidney was recently shown to depend on its association with collectrin (Tmem27...

  11. Lunar dust transport and potential interactions with power system components

    International Nuclear Information System (INIS)

    Katzan, C.M.; Edwards, J.L.

    1991-11-01

    The lunar surface is covered by a thick blanket of fine dust. This dust may be readily suspended from the surface and transported by a variety of mechanisms. As a consequence, lunar dust can accumulate on sensitive power components, such as photovoltaic arrays and radiator surfaces, reducing their performance. In addition to natural mechanisms, human activities on the Moon will disturb significant amounts of lunar dust. Of all the mechanisms identified, the most serious is rocket launch and landing. The return of components from the Surveyor III provided a rare opportunity to observe the effects of the nearby landing of the Apollo 12 lunar module. The evidence proved that significant dust accumulation occurred on the Surveyor at a distance of 155 m. From available information on particle suspension and transport mechanisms, a series of models was developed to predict dust accumulation as a function of distance from the lunar module. The accumulation distribution was extrapolated to a future lunar lander scenario. These models indicate that accumulation is expected to be substantial even as far as 2 km from the landing site. Estimates of the performance penalties associated with lunar dust coverage on radiators and photovoltaic arrays are presented. Because of the lunar dust adhesive and cohesive properties, the most practical dust defensive strategy appears to be the protection of sensitive components from the arrival of lunar dust by location, orientation, or barriers

  12. Lunar dust transport and potential interactions with power system components

    Energy Technology Data Exchange (ETDEWEB)

    Katzan, C.M.; Edwards, J.L.

    1991-11-01

    The lunar surface is covered by a thick blanket of fine dust. This dust may be readily suspended from the surface and transported by a variety of mechanisms. As a consequence, lunar dust can accumulate on sensitive power components, such as photovoltaic arrays and radiator surfaces, reducing their performance. In addition to natural mechanisms, human activities on the Moon will disturb significant amounts of lunar dust. Of all the mechanisms identified, the most serious is rocket launch and landing. The return of components from the Surveyor III provided a rare opportunity to observe the effects of the nearby landing of the Apollo 12 lunar module. The evidence proved that significant dust accumulation occurred on the Surveyor at a distance of 155 m. From available information on particle suspension and transport mechanisms, a series of models was developed to predict dust accumulation as a function of distance from the lunar module. The accumulation distribution was extrapolated to a future lunar lander scenario. These models indicate that accumulation is expected to be substantial even as far as 2 km from the landing site. Estimates of the performance penalties associated with lunar dust coverage on radiators and photovoltaic arrays are presented. Because of the lunar dust adhesive and cohesive properties, the most practical dust defensive strategy appears to be the protection of sensitive components from the arrival of lunar dust by location, orientation, or barriers.

  13. Effect of temperature on the transport of solvents through PTMSP under ultra-high pressures

    International Nuclear Information System (INIS)

    Grekhov, A M; Belogorlov, A A; Eremin, Yu S; Pastukhova, E V; Yushkin, A A; Volkov, A V

    2016-01-01

    Despite a large number of studies, by now there is no any definitive explanation of the solvent transport mechanism in nanostructured polymer materials. Both convective and diffusive transport of solvents can be observed in these materials. The study of the solvents permeability at different temperatures and pressures allow the variation of the physical parameters and structure of the solvent-membrane interaction thus becoming the key factor in the understanding of the fundamental aspects of the selective transport process in nanostructured polymer membranes. The paper presents the study of ethanol, propanol and water transport through poly [1- (trimethylsilyl)-l-propine] (PTMSP) at pressures 50-150 atm and temperature up to 90°C. The study was done by the method of pressure dynamic decay. As the temperature rises, the permeability of ethanol and propanol through PTMSP is shown to increase in proportion to decreasing viscosity that denotes a convective type of transport. As for water, the permeability change is thermo-activated that is typical for a diffusive type of transport. This difference in the transport characteristics can be related to a change in the membrane structure and energetic characteristics of the solvent-polymer interaction. (paper)

  14. Transport of fission products in matrix and graphite

    International Nuclear Information System (INIS)

    Hoinkis, E.

    1983-06-01

    In the past years new experimental methods were applied to or developed for the investigation of fission product transport in graphitic materials and to characterization of the materials. Models for fission product transport and computer codes for the calculation of core release rates were improved. Many data became available from analysis of concentration profiles in HTR-fuel elements. New work on the effect on diffusion of graphite corrosion, fast neutron flux and fluence, heat treatment, chemical interactions and helium pressure was reported on recently or was in progress in several laboratories. It seemed to be the right time to discuss the status of transport of metallic fission products in general, and in particular the relationship between structural and transport properties. Following a suggestion a Colloquium was organized at the HMI Berlin. Interdisciplinary discussions were stimulated by only inviting a limited number of participants who work in different fields of graphite and fission product transport research. (orig./RW)

  15. Transportation System Concept of Operations

    Energy Technology Data Exchange (ETDEWEB)

    N. Slater-Thompson

    2006-08-16

    The Nuclear Waste Policy Act of 1982 (NWPA), as amended, authorized the DOE to develop and manage a Federal system for the disposal of SNF and HLW. OCRWM was created to manage acceptance and disposal of SNF and HLW in a manner that protects public health, safety, and the environment; enhances national and energy security; and merits public confidence. This responsibility includes managing the transportation of SNF and HLW from origin sites to the Repository for disposal. The Transportation System Concept of Operations is the core high-level OCRWM document written to describe the Transportation System integrated design and present the vision, mission, and goals for Transportation System operations. By defining the functions, processes, and critical interfaces of this system early in the system development phase, programmatic risks are minimized, system costs are contained, and system operations are better managed, safer, and more secure. This document also facilitates discussions and understanding among parties responsible for the design, development, and operation of the Transportation System. Such understanding is important for the timely development of system requirements and identification of system interfaces. Information provided in the Transportation System Concept of Operations includes: the functions and key components of the Transportation System; system component interactions; flows of information within the system; the general operating sequences; and the internal and external factors affecting transportation operations. The Transportation System Concept of Operations reflects OCRWM's overall waste management system policies and mission objectives, and as such provides a description of the preferred state of system operation. The description of general Transportation System operating functions in the Transportation System Concept of Operations is the first step in the OCRWM systems engineering process, establishing the starting point for the lower

  16. Transport infrastructure and technology: Investment, externalities, and general equilibrium effects

    Energy Technology Data Exchange (ETDEWEB)

    Van den Bergh, Jeroen C.J.M.; Nijkamp, P. [Faculty of Economics, Free University, Amsterdam (Netherlands)

    1993-04-01

    The paper addresses the use of general equilibrium models to analyze transportation policies. After a discussion of possible approaches, a representative set of static and dynamic models is developed and investigated, which focus on the interaction between general equilibrium, transport, infrastructure and environment. It is shown that each of these allows one to deal with specific types of policy questions. More technical modelling issues are dealt with as well, e.g. returns to scale, production functions, and disaggregation. Finally, attention is devoted to freight transport in a multisectoral production setting. 5 figs., 8 refs.

  17. A study on the characteristics of colloid-associated radionuclide transport in porous media

    International Nuclear Information System (INIS)

    Jeong, Yun Chang

    1997-02-01

    Recently, the radionuclide transport in the form of colloids has been focused intensively in the safety assessment of a radioactive waste repository. As colloids are considered to be able to increase the transport rate of radionuclide through geologic media, the transport of radionuclide should be adjusted by the presence of colloids. The migration of dissolved radionuclide is expected to depend on various process such as advection, dispersion and interactions with soils, and, in addition, the transport of colloid-mediated radionuclide is considered to be more complicated because of the interactions between radionuclides and colloids. In this paper the migration behavior of colloid-associated radionuclides within subsurface are reviewed and studied in detail. The colloid-mediated transport system was modelled and simulated in order to illustrate the effects of colloids on the transport of radionuclide in the aquifer system. The transport rate of radionuclide is mainly controlled by a retardation factor which is controlled by colloidal behaviors, degree of adsorption, and the related geologic parameters. Therefore it is necessary to carefully understand the accelerating tendency of the retardation difference factor, and in this study the trends are analyzed, described and the retardation difference factor is mathematically defined, simplified and applied practically to the safety and performance assessment of a future repository

  18. Grain transport mechanics in shallow overland flow

    Science.gov (United States)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flow. The two phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a disper...

  19. Pair production from nuclear collisions and cosmic ray transport

    International Nuclear Information System (INIS)

    Norbury, John W

    2006-01-01

    Modern cosmic ray transport codes, that are capable of use for a variety of applications, need to include all significant atomic, nuclear and particle reactions at a variety of energies. Lepton pair production from nucleus-nucleus collisions has not been included in transport codes to date. Using the methods of Baur, Bertulani and Baron, the present report provides estimates of electron-positron pair production cross sections for nuclei and energies relevant to cosmic ray transport. It is shown that the cross sections are large compared to other typical processes such as single neutron removal due to strong or electromagnetic interactions. Therefore, lepton pair production may need to be included in some transport code applications involving MeV electrons. (brief report)

  20. Charge-transport simulations in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    May, Falk

    2012-07-06

    In this thesis we have extended the methods for microscopic charge-transport simulations for organic semiconductors, where weak intermolecular interactions lead to spatially localized charge carriers, and the charge transport occurs as an activated hopping process between diabatic states. In addition to weak electronic couplings between these states, different electrostatic environments in the organic material lead to a broadening of the density of states for the charge energies which limits carrier mobilities. The contributions to the method development include (i) the derivation of a bimolecular charge-transfer rate, (ii) the efficient evaluation of intermolecular (outer-sphere) reorganization energies, (iii) the investigation of effects of conformational disorder on intramolecular reorganization energies or internal site energies and (iv) the inclusion of self-consistent polarization interactions for calculation of charge energies. These methods were applied to study charge transport in amorphous phases of small molecules used in the emission layer of organic light emitting diodes (OLED). When bulky substituents are attached to an aromatic core in order to adjust energy levels or prevent crystallization, a small amount of delocalization of the frontier orbital to the substituents can increase electronic couplings between neighboring molecules. This leads to improved charge-transfer rates and, hence, larger charge-mobility. We therefore suggest using the mesomeric effect (as opposed to the inductive effect) when attaching substituents to aromatic cores, which is necessary for example in deep blue OLEDs, where the energy levels of a host molecule have to be adjusted to those of the emitter. Furthermore, the energy landscape for charges in an amorphous phase cannot be predicted by mesoscopic models because they approximate the realistic morphology by a lattice and represent molecular charge distributions in a multipole expansion. The microscopic approach shows that

  1. Overview of TFTR transport studies

    International Nuclear Information System (INIS)

    Hawryluk, R.J.; Arunasalam, V.; Beer, M.; Bell, M.; Bell, R.; Biglari, H.; Bitter, M.; Boivin, R.; Bretz, N.L.; Budny, R.; Cheng, C.Z.; Chu, T.K.; Cohen, S.A.; Cowley, S.; Efthimion, P.C.; Fredrickson, E.; Furth, H.P.; Goldston, R.J.; Greene, G.; Grek, B.; Grisham, L.R.; Hammett, G.; Hill, K.W.; Hosea, J.; Hulse, R.A.; Hsuan, H.; Janos, A.; Jassby, D.; Jobes, F.C.; Johnson, D.W.; Johnson, L.C.; Kieras-Phillips, C.; Kilpatrick, S.J.; Kugel, H.; La Marche, P.H.; LeBlanc, B.; Manos, D.M.; Mansfield, D.K.; Mazzucato, E.; McCarthy, M.P.; McCune, D.C.; McGuire, K.M.; Meade, D.M.; Medley, S.S.; Mikkelsen, D.R.; Monticello, D.; Motley, R.; Mueller, D.; Nazikian, R.; Owens, D.K.; Park, H.; Park, W.; Paul, S.; Perkins, F.; Ramsey, A.T.; Redi, M.H.; Rewoldt, G.; Roquemore, A.L.; Rutherford, P.H.; Schilling, G.; Schivell, J.; Schmidt, G.L.; Scott, S.D.; Stevens, J.; Stratton, B.C.; Stodiek, W.; Synakowski, E.; Tang, W.; Taylor, G.; Timberlake, J.R.; Towner, H.H.; Ulrickson, M.; von Goeler, S.; Wieland, R.; Williams, M.; Wilson, J.R.; Wong, K.L.; Yamada, M.; Yoshikawa, S.; Young, K.M.; Zarnstorff, M.C.; Zweben, S.J.; Bush, C.E.; Fonck, R.J; Roberts, D.; Heidbrink, W.; Kesner, J.; Marmar, E.S.; Snipes, J.; Takase, Y.; Terry, J.; Mauel, M.; Navratil, G.A.; Sabbagh, S.; Nagayama, Y.; Pitcher, S.

    1991-10-01

    A review of TFTR plasma transport studies is presented. Parallel transport and the confinement of suprathermal ions are found to be relatively well described by theory. Cross-field transport of the thermal plasma, however, is anomalous with the momentum diffusivity being comparable to the ion thermal diffusivity and larger than the electron thermal diffusivity in neutral beam heated discharges. Perturbative experiments have studied non-linear dependencies in the transport coefficients and examined the role of possible non-local phenomena. The underlying turbulence has been studied using microwave scattering, beam emission spectroscopy and microwave reflectometry over a much broader range in k perpendicular than previously possible. Results indicate the existence of large-wavelength fluctuations correlated with enhanced transport. MHD instabilities set important operational constraints. However, by modifying the current profile using current ramp-down techniques, it has been possible to extend the operating regime to higher values of both var-epsilon β p and normalized β T . In addition, the interaction of MHD fluctuations with fast ions, of potential relevance to α-particle confinement in D-T plasmas, has been investigated. The installation of carbon-carbon composite tiles and improvements in wall conditioning, in particular the use of Li pellet injection to reduce the carbon recycling, continue to be important in the improvement of plasma performance. 96 refs., 16 figs

  2. Barriers to Superfast Water Transport in Carbon Nanotube Membranes

    DEFF Research Database (Denmark)

    Walther, Jens Honore; Ritos, Konstantinos; Cruz-Chu, Eduardo R.

    2013-01-01

    Carbon nanotube (CNT) membranes hold the promise of extraordinary fast water transport for applications such as energy efficient filtration and molecular level drug delivery. However, experiments and computations have reported flow rate enhancements over continuum hydrodynamics that contradict each...... over the continuum predictions. These rates are far below those reported experimentally. The results suggest that the reported superfast water transport rates cannot be attributed to interactions of water with pristine CNTs alone....

  3. Coupling effect on the electronic transport through dimolecular junctions

    International Nuclear Information System (INIS)

    Long, Meng-Qiu; Wang, Lingling; Chen, Ke-Qiu; Li, Xiao-Fei; Zou, B.S.; Shuai, Z.

    2007-01-01

    Using nonequilibrium Green's function and first-principle calculations, we investigate the transport behaviors of a dimolecule device with two 1,4-Dithiolbenzenes (DTB) sandwiched between two gold electrodes. The results show that the intermolecular coupling effect plays an important role in the conducting behavior of the system. By changing the dihedral angles between the two DTB molecules, namely changing the magnitude of the intermolecular interaction, a different transport behavior can be observed in the system

  4. Role of transporters in placental transfer of drugs

    International Nuclear Information System (INIS)

    Ganapathy, Vadivel; Prasad, Puttur D.

    2005-01-01

    Human placenta functions as an important transport organ that mediates the exchange of nutrients and metabolites between maternal and fetal circulations. This function is made possible because of the expression of a multitude of transport proteins in the placental syncytiotrophoblast with differential localization in the maternal-facing brush border membrane versus the fetal-facing basal membrane. Even though the physiological role of most of these transport proteins is to handle nutrients, many of them interact with xenobiotics and pharmacological agents. These transport proteins therefore play a critical role in the disposition of drugs across the maternal-fetal interface, with some transporters facilitating the entry of drugs from maternal circulation into fetal circulation whereas others preventing such entry by actively eliminating drugs from the placenta back into maternal circulation. The net result as to whether the placenta enhances the exposure of the developing fetus to drugs and xenobiotics or functions as a barrier to protect the fetus from such agents depends on the types of transporters expressed in the brush border membrane and basal membrane of the syncytiotrophoblast and on the functional mode of these transporters (influx versus efflux)

  5. A continuum mechanics-based musculo-mechanical model for esophageal transport

    Science.gov (United States)

    Kou, Wenjun; Griffith, Boyce E.; Pandolfino, John E.; Kahrilas, Peter J.; Patankar, Neelesh A.

    2017-11-01

    In this work, we extend our previous esophageal transport model using an immersed boundary (IB) method with discrete fiber-based structural model, to one using a continuum mechanics-based model that is approximated based on finite elements (IB-FE). To deal with the leakage of flow when the Lagrangian mesh becomes coarser than the fluid mesh, we employ adaptive interaction quadrature points to deal with Lagrangian-Eulerian interaction equations based on a previous work (Griffith and Luo [1]). In particular, we introduce a new anisotropic adaptive interaction quadrature rule. The new rule permits us to vary the interaction quadrature points not only at each time-step and element but also at different orientations per element. This helps to avoid the leakage issue without sacrificing the computational efficiency and accuracy in dealing with the interaction equations. For the material model, we extend our previous fiber-based model to a continuum-based model. We present formulations for general fiber-reinforced material models in the IB-FE framework. The new material model can handle non-linear elasticity and fiber-matrix interactions, and thus permits us to consider more realistic material behavior of biological tissues. To validate our method, we first study a case in which a three-dimensional short tube is dilated. Results on the pressure-displacement relationship and the stress distribution matches very well with those obtained from the implicit FE method. We remark that in our IB-FE case, the three-dimensional tube undergoes a very large deformation and the Lagrangian mesh-size becomes about 6 times of Eulerian mesh-size in the circumferential orientation. To validate the performance of the method in handling fiber-matrix material models, we perform a second study on dilating a long fiber-reinforced tube. Errors are small when we compare numerical solutions with analytical solutions. The technique is then applied to the problem of esophageal transport. We use two

  6. Coal transportation research and information needs

    Energy Technology Data Exchange (ETDEWEB)

    Eck, R.W. (West Virginia Univ., Morgantown); Hui, C.Y.

    1978-09-01

    This paper examines some of the existing and emerging issues of interest to engineers and planners dealing with coal transportation. One conclusion is that any research or data collection efforts in this field must be of a multidisciplinary nature. Not only must transportation planners, highway engineers, maintenance engineers, and soils engineers work together but, in addition, engineers will need to work with geologists, economists, and marketing specialists for effective planning, design, and operation of the coal transportation system. Earlier sections of this paper may have given the erroneous impression that all future research should concentrate on problems of transporting coal by truck. Although the West Virginia coal conversion study documented information deficiencies relative to the highway transportation of coal, research efforts involving railroads and waterways should continue. There is a serious need for research and information relative to the interactions between modes. For example, in order to predict the impact of local coal conversions on rail and barge systems that serve retailers, it is necessary to have a knowledge of the typical volumes that would be required by retail facilities, frequency of delivery to retail yards, and transportation distances involved mine and retailer. This paper deals with relatively short-term planning, however, information is required on the long-range future of the coal industry. Decision makers involved with providing an adequate coal transportation system must have information on the future role that coal will play in United States energy policy. (MCW)

  7. Controlling Ionic Transport for Device Design in Synthetic Nanopores

    Science.gov (United States)

    Kalman, Eric Boyd

    Polymer nanopores present a number of behaviors not seen in microscale systems, such as ion current rectification, ionic selectivity, size exclusion and potential dependent ion concentrations in and near the pore. The existence of these effects stems from the small size of nanopores with respect to the characteristic length scales of surface interactions at the interface between the nanopore surface and the solution within it. The large surface-to-volume ratio due to the nanoscale geometry of a nanopore, as well as similarity in scale between geometry and interaction demands the solution interact with the nanopore walls. As surfaces in solution almost always carry residual charge, these surface forces are primarily the electrostatic interactions between the charge groups on the pore surface and the ions in solution. These interactions may be used by the experimentalist to control ionic transport through synthetic nanopores, and use them as a template for the construction of devices. In this research, we present our work on creating a number of ionic analogs to seminal electronic devices, specifically diodes, and transistors, by controlling ionic transport through the electrostatic interactions between a single synthetic nanopore and ions. Control is achieved by "doping" the effective charge carrier concentration in specific regions of the nanopore through manipulation of the pore's surface charge. This manipulation occurs through two mechanisms: chemical modification of the surface charge and electrostatic manipulation of the local internal nanopore potential using a gate electrode. Additionally, the innate selectivity of the charged nanopores walls allows for the separation of charges in solution. This well-known effect, which spawns measureable quantities, the streaming potential and current, has been used to create nanoscale water desalination membranes. We attempt to create a device using membranes with large nanopore densities for the desalination of water

  8. Modeling reactive geochemical transport of concentrated aqueous solutions in variably saturated media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoxiang; Zheng, Zuoping; Wan, Jiamin

    2004-01-28

    Concentrated aqueous solutions (CAS) have unique thermodynamic and physical properties. Chemical components in CAS are incompletely dissociated, especially those containing divalent or polyvalent ions. The problem is further complicated by the interaction between CAS flow processes and the naturally heterogeneous sediments. As the CAS migrates through the porous media, the composition may be altered subject to fluid-rock interactions. To effectively model reactive transport of CAS, we must take into account ion-interaction. A combination of the Pitzer ion-interaction and the ion-association model would be an appropriate way to deal with multiple-component systems if the Pitzer' parameters and thermodynamic data of dissolved components and the related minerals are available. To quantify the complicated coupling of CAS flow and transport, as well as the involved chemical reactions in natural and engineered systems, we have substantially extended an existing reactive biogeochemical transport code, BIO-CORE{sup 2D}{copyright}, by incorporating a comprehensive Pitzer ion-interaction model. In the present paper, the model, and two test cases against measured data were briefly introduced. Finally we present an application to simulate a laboratory column experiment studying the leakage of the high alkaline waste fluid stored in Hanford (a site of the U.S. Department of Energy, located in Washington State, USA). With the Pitzer ion-interaction ionic activity model, our simulation captures measured pH evolution. The simulation indicates that all the reactions controlling the pH evolution, including cation exchanges, mineral precipitation and dissolution, are coupled.

  9. Modeling coupled nanoparticle aggregation and transport in porous media: a Lagrangian approach.

    Science.gov (United States)

    Taghavy, Amir; Pennell, Kurt D; Abriola, Linda M

    2015-01-01

    Changes in nanoparticle size and shape due to particle-particle interactions (i.e., aggregation or agglomeration) may significantly alter particle mobility and retention in porous media. To date, however, few modeling studies have considered the coupling of transport and particle aggregation processes. The majority of particle transport models employ an Eulerian modeling framework and are, consequently, limited in the types of collisions and aggregate sizes that can be considered. In this work, a more general Lagrangian modeling framework is developed and implemented to explore coupled nanoparticle aggregation and transport processes. The model was verified through comparison of model simulations to published results of an experimental and Eulerian modeling study (Raychoudhury et al., 2012) of carboxymethyl cellulose (CMC)-modified nano-sized zero-valent iron particle (nZVI) transport and retention in water-saturated sand columns. A model sensitivity analysis reveals the influence of influent particle concentration (ca. 70 to 700 mg/L), primary particle size (10-100 nm) and pore water velocity (ca. 1-6 m/day) on particle-particle, and, consequently, particle-collector interactions. Model simulations demonstrate that, when environmental conditions promote particle-particle interactions, neglecting aggregation effects can lead to under- or over-estimation of nanoparticle mobility. Results also suggest that the extent to which higher order particle-particle collisions influence aggregation kinetics will increase with the fraction of primary particles. This work demonstrates the potential importance of time-dependent aggregation processes on nanop