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Sample records for active transport processes

  1. Energetics of active transport processes.

    PubMed

    Essig, A; Caplan, S R

    1968-12-01

    Discussions of active transport usually assume stoichiometry between the rate of transport J(+) and the metabolic rate J(r). However, the observation of a linear relationship between J(+) and J(r) does not imply a stoichiometric relationship, i.e., complete coupling. Since coupling may possibly be incomplete, we examine systems of an arbitrary degree of coupling q, regarding stoichiometry as a limiting case. We consider a sodium pump, with J(+) and J(r) linear functions of the electrochemical potential difference, -X(+), and the chemical affinity of the metabolic driving reaction, A. The affinity is well defined even for various complex reaction pathways. Incorporation of a series barrier and a parallel leak does not affect the linearity of the composite observable system. The affinity of some region of the metabolic chain may be maintained constant, either by large pools of reactants or by regulation. If so, this affinity can be evaluated by two independent methods. Sodium transport is conveniently characterized by the open-circuit potential (Deltapsi)(I=0) and the natural limits, level flow (J(+))(X+=0), and static head X(0) (+) = (X(+))(J+=0). With high degrees of coupling -X(0) (+)/F approaches the electromotive force E(Na) (Ussing); -X(0) (+)/F cannot be identified with ((RT/F) ln f)(X+=0), where f is the flux ratio. The efficiency eta = -J(+)X(+)/J(r)A is of significance only when appreciable energy is being converted from one form to another. When either J(+) or -X(+) is small eta is low; the significant parameters are then the efficacies epsilon(J+) = J(+)/J(r)A and epsilon(X+) = -X(+)/J(r)A, respectively maximal at level flow and static head. Leak increases both J(+) and epsilon(J+) for isotonic saline reabsorption, but diminishes -X(0) (+) and epsilon(Xfemale symbol). Electrical resistance reflects both passive parameters and metabolism. Various fundamental relations are preserved despite coupling of passive ion and water flows. PMID:5713453

  2. Saharan Dust, Transport Processes, and Possible Impacts on Hurricane Activities

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, K. M.

    2010-01-01

    In this paper, we present observational evidence of significant relationships between Saharan dust outbreak, and African Easterly wave activities and hurricane activities. We found two dominant paths of transport of Saharan dust: a northern path, centered at 25degN associated with eastward propagating 6-19 days waves over northern Africa, and a southern path centered at 15degN, associated with the AEW, and the Atlantic ITCZ. Seasons with stronger dust outbreak from the southern path are associated with a drier atmosphere over the Maximum Development Region (MDR) and reduction in tropical cyclone and hurricane activities in the MDR. Seasons with stronger outbreak from the northern path are associated with a cooler N. Atlantic, and suppressed hurricane in the western Atlantic basin.

  3. Community Vision and Interagency Alignment: A Community Planning Process to Promote Active Transportation.

    PubMed

    DeGregory, Sarah Timmins; Chaudhury, Nupur; Kennedy, Patrick; Noyes, Philip; Maybank, Aletha

    2016-04-01

    In 2010, the Brooklyn Active Transportation Community Planning Initiative launched in 2 New York City neighborhoods. Over a 2-year planning period, residents participated in surveys, school and community forums, neighborhood street assessments, and activation events-activities that highlighted the need for safer streets locally. Consensus among residents and key multisectoral stakeholders, including city agencies and community-based organizations, was garnered in support of a planned expansion of bicycling infrastructure. The process of building on community assets and applying a collective impact approach yielded changes in the built environment, attracted new partners and resources, and helped to restore a sense of power among residents. PMID:26959270

  4. Competition and cooperation between active intra-network and passive extra-network transport processes

    PubMed Central

    Maruyama, Dan; Zochowski, Michal

    2014-01-01

    Many networks are embedded in physical space and often interact with it. This interaction can be exemplified through constraints exerted on network topology, or through interactions of processes defined on a network with those that are linked to the space that the network is embedded within, leading to complex dynamics. Here we discuss an example of such an interaction in which a signaling agent is actively transported through the network edges and, at the same time, spreads passively through space due to diffusion. We show that these two processes cooperate or compete depending on the network topology leading to complex dynamics. PMID:24920178

  5. Transport processes in tumours.

    PubMed

    Quastel, J H

    1965-12-01

    The characteristic features of transport systems controlling influx into tumour cells of nutrients and other chemicals are briefly described. Two notable features of transport of amino acids into tumour cells have been observed: extensive accumulation against a concentration gradient and equal accumulations, whether conditions are aerobic or anaerobic, provided glucose is present. This combination of features has not been observed in the majority of normal mammalian tissues so far examined. Important for considerations of chemotherapy is the ability of tumour transport carriers to transfer substances related in structure to amino acids and other nutrients. Amino acid analogues, for example, can either block transport of natural amino acids or can be transported into the cell where they may interfere with various aspects of amino acid metabolism. The study of transport carriers is essential for an understanding of tumour-host relationships and for considerations of chemotherapy. PMID:5842595

  6. EPAct Transportation Regulatory Activities

    SciTech Connect

    2011-11-21

    The U.S. Department of Energy's (DOE) Vehicle Technologies Program manages several transportation regulatory activities established by the Energy Policy Act of 1992 (EPAct), as amended by the Energy Conservation Reauthorization Act of 1998, EPAct 2005, and the Energy Independence and Security Act of 2007 (EISA).

  7. Crew Transportation Technical Management Processes

    NASA Technical Reports Server (NTRS)

    Mckinnie, John M. (Compiler); Lueders, Kathryn L. (Compiler)

    2013-01-01

    Under the guidance of processes provided by Crew Transportation Plan (CCT-PLN-1100), this document, with its sister documents, International Space Station (ISS) Crew Transportation and Services Requirements Document (CCT-REQ-1130), Crew Transportation Technical Standards and Design Evaluation Criteria (CCT-STD-1140), Crew Transportation Operations Standards (CCT STD-1150), and ISS to Commercial Orbital Transportation Services Interface Requirements Document (SSP 50808), provides the basis for a National Aeronautics and Space Administration (NASA) certification for services to the ISS for the Commercial Provider. When NASA Crew Transportation System (CTS) certification is achieved for ISS transportation, the Commercial Provider will be eligible to provide services to and from the ISS during the services phase.

  8. Transport processes of the legume symbiosome membrane

    PubMed Central

    Clarke, Victoria C.; Loughlin, Patrick C.; Day, David A.; Smith, Penelope M. C.

    2014-01-01

    The symbiosome membrane (SM) is a physical barrier between the host plant and nitrogen-fixing bacteria in the legume:rhizobia symbiosis, and represents a regulated interface for the movement of solutes between the symbionts that is under plant control. The primary nutrient exchange across the SM is the transport of a carbon energy source from plant to bacteroid in exchange for fixed nitrogen. At a biochemical level two channels have been implicated in movement of fixed nitrogen across the SM and a uniporter that transports monovalent dicarboxylate ions has been characterized that would transport fixed carbon. The aquaporin NOD26 may provide a channel for ammonia, but the genes encoding the other transporters have not been identified. Transport of several other solutes, including calcium and potassium, have been demonstrated in isolated symbiosomes, and genes encoding transport systems for the movement of iron, nitrate, sulfate, and zinc in nodules have been identified. However, definitively matching transport activities with these genes has proved difficult and many further transport processes are expected on the SM to facilitate the movement of nutrients between the symbionts. Recently, work detailing the SM proteome in soybean has been completed, contributing significantly to the database of known SM proteins. This represents a valuable resource for the identification of transporter protein candidates, some of which may correspond to transport processes previously described, or to novel transport systems in the symbiosis. Putative transporters identified from the proteome include homologs of transporters of sulfate, calcium, peptides, and various metal ions. Here we review current knowledge of transport processes of the SM and discuss the requirements for additional transport routes of other nutrients exchanged in the symbiosis, with a focus on transport systems identified through the soybean SM proteome. PMID:25566274

  9. Superiority of the S,S conformation in diverse pharmacological processes: Intestinal transport and entry inhibition activity of novel anti-HIV drug lead.

    PubMed

    Fanous, Joseph; Swed, Avi; Joubran, Salim; Hurevich, Mattan; Britan-Rosich, Elena; Kotler, Moshe; Gilon, Chaim; Hoffman, Amnon

    2015-11-30

    Chirality is an important aspect in many pharmacological processes including drug transport and metabolism. The current investigation examined the stereospecific transport and entry inhibitory activity of four diastereomers derived from a small (macrocyclic) molecule that has two chiral centers. These molecules were designed to mimic the interaction between CD4 and gp120 site of HIV-1 and thereby to function as entry inhibitor(s). Intestinal permeability was assessed by ex-vivo model using excised rat intestine mounted in side-by-side diffusion chambers. The entry inhibitory activity was monitored using indicator HeLa-CD4-LTR-beta-gal cells (MAGI assay). The (S/S) diastereomer, named CG-1, exhibited superiority in both unrelated tested biological processes: (I) high transport through the intestine and (II) entry inhibition activity (in the low μM range). The permeability screening revealed a unique transporter-mediated absorption pathway of CG-1, suggesting a significant role of the molecule's conformation on the mechanism of intestinal absorption. Here we highlight that only the S,S enantiomer (CG-1) has both (I) promising anti HIV-1 entry inhibitory properties and (II) high transporter mediated intestinal permeability. Hence we suggest preference in pharmacological processes to the S,S conformation. This report augments the knowledge regarding stereoselectivity in receptor mediated and protein-protein interaction processes. PMID:26392249

  10. MBAS (Methylene Blue Active Substances) and LAS (Linear Alkylbenzene Sulphonates) in Mediterranean coastal aerosols: Sources and transport processes

    NASA Astrophysics Data System (ADS)

    Becagli, S.; Ghedini, C.; Peeters, S.; Rottiers, A.; Traversi, R.; Udisti, R.; Chiari, M.; Jalba, A.; Despiau, S.; Dayan, U.; Temara, A.

    2011-12-01

    Methylene Blue Active Substances (MBAS) and Linear Alkylbenzene Sulphonates (LAS) concentrations, together with organic carbon and ions were measured in atmospheric coastal aerosols in the NW Mediterranean Basin. Previous studies have suggested that the presence of surfactants in coastal aerosols may result in vegetation damage without specifically detecting or quantifying these surfactants. Coastal aerosols were collected at a remote site (Porquerolles Island-Var, France) and at a more anthropised site (San Rossore National Park-Tuscany, Italy). The chemical data were interpreted according to a comprehensive local meteorological analysis aiming to decipher the airborne source and transport processes of these classes of compounds. The LAS concentration (anthropogenic surfactants) was measured in the samples using LC-MS/MS, a specific analytical method. The values were compared with the MBAS concentration, determined by a non-specific analytical method. At Porquerolles, the MBAS concentration (103 ± 93 ng m -3) in the summer samples was significantly higher than in the winter samples. In contrast, LAS concentrations were rarely greater than in the blank filters. At San Rossore, the mean annual MBAS concentration (887 ± 473 ng m -3 in PM10) contributed about 10% to the total atmospheric particulate organic matter. LAS mean concentration in these same aerosol samples was 11.5 ± 10.5 ng m -3. A similar MBAS (529 ± 454 ng m -3) - LAS (7.1 ± 4.1 ng m -3 LAS) ratio of ˜75 was measured in the fine (PM2.5) aerosol fraction. No linear correlation was found between MBAS and LAS concentrations. At San Rossore site the variation of LAS concentrations was studied on a daily basis over a year. The LAS concentrations in the coarse fraction (PM10-2.5) were higher during strong sea storm conditions, characterized by strong air flow coming from the sea sector. These events, occurring with more intensity in winter, promoted the formation of primary marine aerosols containing LAS

  11. Laboratory Exercise on Active Transport.

    ERIC Educational Resources Information Center

    Stalheim-Smith, Ann; Fitch, Greg K.

    1985-01-01

    Describes a laboratory exercise which demonstrates qualitatively the specificity of the transport mechanism, including a consideration of the competitive inhibition, and the role of adenosine triphosphate (ATP) in active transport. The exercise, which can be completed in two to three hours by groups of four students, consistently produces reliable…

  12. Transport processes in space plasmas

    SciTech Connect

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

    1997-08-01

    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.

  13. Rotary kilns - transport phenomena and transport processes

    SciTech Connect

    Boateng, A.

    2008-01-15

    Rotary kilns and rotating industrial drying ovens are used for a wide variety of applications including processing raw minerals and feedstocks as well as heat-treating hazardous wastes. They are particularly critical in the manufacture of Portland cement. Their design and operation is critical to their efficient usage, which if done incorrectly can result in improperly treated materials and excessive, high fuel costs. This book treats all engineering aspects of rotary kilns, including thermal and fluid principles involved in their operation, as well as how to properly design an engineering process that uses rotary kilns. Chapter 1: The Rotary Kiln Evolution and Phenomenon Chapter 2: Basic Description of Rotary Kiln Operation Chapter 3: Freeboard Aerodynamic Phenomena Chapter 4: Granular Flows in Rotary Kilns Chapter 5: Mixing and Segregation Chapter 6: Combustion and Flame - includes section on types of fuels used in rotary kilns, coal types, ranking and analysis, petroleum coke combustion, scrap tire combustion, pulverized fuel (coal/coke) firing in kilns, pulverized fuel delivery and firing systems. Chapter 7: Freeboard Heat Transfer Chapter 8: Heat Transfer Processes in the Rotary Kiln Bed Chapter 9: Mass and Energy Balance Chapter 10: Rotary Kiln Minerals Process Applications.

  14. A Combined Impact-Process Evaluation of a Program Promoting Active Transport to School: Understanding the Factors That Shaped Program Effectiveness

    PubMed Central

    Crawford, S.; Garrard, J.

    2013-01-01

    This mixed methods study was a comprehensive impact-process evaluation of the Ride2School program in metropolitan and regional areas in Victoria, Australia. The program aimed to promote transport to school for primary school children. Qualitative and quantitative data were collected at baseline and followup from two primary schools involved in the pilot phase of the program and two matched comparison schools, and a further 13 primary schools that participated in the implementation phase of the program. Classroom surveys, structured and unstructured observations, and interviews with Ride2School program staff were used to evaluate the pilot program. For the 13 schools in the second phase of the program, parents and students completed questionnaires at baseline (N = 889) and followup (N = 761). Based on the quantitative data, there was little evidence of an overall increase in active transport to school across participating schools, although impacts varied among individual schools. Qualitative data in the form of observations, interviews, and focus group discussions with students, school staff, and program staff provided insight into the reasons for variable program impacts. This paper highlights the benefits of undertaking a mixed methods approach to evaluating active transport to school programs that enables both measurement and understanding of program impacts. PMID:23606865

  15. A replacement of the active-site aspartic acid residue 293 in mouse cathepsin D affects its intracellular stability, processing and transport in HEK-293 cells.

    PubMed Central

    Partanen, Sanna; Storch, Stephan; Löffler, Hans-Gerhard; Hasilik, Andrej; Tyynelä, Jaana; Braulke, Thomas

    2003-01-01

    The substitution of an active-site aspartic acid residue by asparagine in the lysosomal protease cathepsin D (CTSD) results in a loss of enzyme activity and severe cerebrocortical atrophy in a novel form of neuronal ceroid lipofuscinosis in sheep [Tyynelä, Sohar, Sleat, Gin, Donnelly, Baumann, Haltia and Lobel (2000) EMBO J. 19, 2786-2792]. In the present study we have introduced the corresponding mutation by replacing aspartic acid residue 293 with asparagine (D293N) into the mouse CTSD cDNA to analyse its effect on synthesis, transport and stability in transfected HEK-293 cells. The complete inactivation of mutant D293N mouse CTSD was confirmed by a newly developed fluorimetric quantification system. Moreover, in the heterologous overexpression systems used, mutant D293N mouse CTSD was apparently unstable and proteolytically modified during early steps of the secretory pathway, resulting in a loss of mass by about 1 kDa. In the affected sheep, the endogenous mutant enzyme was stable but also showed the shift in its molecular mass. In HEK-293 cells, the transport of the mutant D293N mouse CTSD to the lysosome was delayed and associated with a low secretion rate compared with wild-type CTSD. These data suggest that the mutation may result in a conformational change which affects stability, processing and transport of the enzyme. PMID:12350228

  16. WASTE ACTIVATED SLUDGE PROCESSING

    EPA Science Inventory

    A study was made at pilot scale of a variety of processes for dewatering and stabilization of waste activated sludge from a pure oxygen activated sludge system. Processes evaluated included gravity thickening, dissolved air flotation thickening, basket centrifugation, scroll cent...

  17. Processing of Activated Core Components

    SciTech Connect

    Friske, A.; Gestermann, G.; Finkbeiner, R.

    2003-02-26

    Used activated components from the core of a NPP like control elements, water channels from a BWR, and others like in-core measurement devices need to be processed into waste forms suitable for interim storage, and for the final waste repository. Processing of the activated materials can be undertaken by underwater cutting and packaging or by cutting and high-pressure compaction in a hot cell. A hot cell is available in Germany as a joint investment between GNS and the Karlsruhe Research Center at the latter's site. Special transport equipment is available to transport the components ''as-is'' to the hot cell. Newly designed underwater processing equipment has been designed, constructed, and operated for the special application of NPP decommissioning. This equipment integrates an underwater cutting device with an 80 ton force underwater in-drum compactor.

  18. Lactate Stimulates IL-4 and IL-13 Production in Activated HuT-78 T Lymphocytes Through a Process That Involves Monocarboxylate Transporters and Protein Hyperacetylation.

    PubMed

    Wagner, Waldemar; Ciszewski, Wojciech; Kania, Katarzyna; Dastych, Jarosław

    2016-05-01

    Mucosal cells of the gastrointestinal and female reproductive tract are constantly exposed to l- and d-lactate of bacterial origin. These compounds not only protect the host from pathogen colonization but also modulate the activity of mucosal immune cells, thereby playing an important role in inflammatory host responses. In this study, we demonstrated that exposure of anti-CD3/CD28 or phorbol 12-myristate 13-acetate (PMA)/ionomycin-activated HuT-78 T lymphocyte cells to 10-20 mM d-lactate significantly increased IL-4 and IL-13 production. Interestingly, the d-lactate isomer, exclusively produced locally by gut or cervicovaginal microbiota, was found to be more potent than the l-isomer. Interestingly, neither of the strong histone deacetylase inhibitors [structurally similar butyrate and suberoylanilide hydroxamic acid (SAHA)] was as effective in the stimulation of IL-13 production as d-lactate. Lactate transport through monocarboxylate transporters was required for lactate-enhanced IL-13 production in a manner that was not hydroxycarboxylic acid receptor 1-dependent. Furthermore, lactate treatment increased the acetylation of GATA-3, a critical regulator of Th1/Th2 differentiation and resulted in H3 and H4 histone hyperacetylation state, which is a characteristic feature of transcriptionally active chromatin. Both lactate isomers also enhanced IL4 and IL13 promoter-driven activity of reporter constructs in murine and human cells. Together, these findings demonstrate that a local millimolar concentration of l- or d-lactate may play an important role in the modulation of inflammation-mediated processes. PMID:27119568

  19. Transport Processes in Dendritic Crystallization

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.

    1984-01-01

    Free dentritic growth refers to the unconstrained development of crystals within a supercooled melt, which is the classical dendrite problem. The development of theoretical understanding of dendritic growth and its experimental status is sketched showing that transport theory and interfacial thermodynamics (capillarity theory) are insufficient ingredients to develop a truly predictive model of dendrite formation. The convenient, but incorrect, notion of maximum velocity was used for many years to estimate the behavior of dendritic transformations until supplanted by modern dynamic stability theory. The proper combinations of transport theory and morphological stability seem to be able to predict the salient aspects of dendritic growth, especially in the neighborhood of the tip.

  20. Signal focusing through active transport

    NASA Astrophysics Data System (ADS)

    Godec, Aljaž; Metzler, Ralf

    2015-07-01

    The accuracy of molecular signaling in biological cells and novel diagnostic devices is ultimately limited by the counting noise floor imposed by the thermal diffusion. Motivated by the fact that messenger RNA and vesicle-engulfed signaling molecules transiently bind to molecular motors and are actively transported in biological cells, we show here that the random active delivery of signaling particles to within a typical diffusion distance to the receptor generically reduces the correlation time of the counting noise. Considering a variety of signaling particle sizes from mRNA to vesicles and cell sizes from prokaryotic to eukaryotic cells, we show that the conditions for active focusing—faster and more precise signaling—are indeed compatible with observations in living cells. Our results improve the understanding of molecular cellular signaling and novel diagnostic devices.

  1. Regulators of Slc4 bicarbonate transporter activity

    PubMed Central

    Thornell, Ian M.; Bevensee, Mark O.

    2015-01-01

    The Slc4 family of transporters is comprised of anion exchangers (AE1-4), Na+-coupled bicarbonate transporters (NCBTs) including electrogenic Na/bicarbonate cotransporters (NBCe1 and NBCe2), electroneutral Na/bicarbonate cotransporters (NBCn1 and NBCn2), and the electroneutral Na-driven Cl-bicarbonate exchanger (NDCBE), as well as a borate transporter (BTR1). These transporters regulate intracellular pH (pHi) and contribute to steady-state pHi, but are also involved in other physiological processes including CO2 carriage by red blood cells and solute secretion/reabsorption across epithelia. Acid-base transporters function as either acid extruders or acid loaders, with the Slc4 proteins moving HCO−3 either into or out of cells. According to results from both molecular and functional studies, multiple Slc4 proteins and/or associated splice variants with similar expected effects on pHi are often found in the same tissue or cell. Such apparent redundancy is likely to be physiologically important. In addition to regulating pHi, a HCO−3 transporter contributes to a cell's ability to fine tune the intracellular regulation of the cotransported/exchanged ion(s) (e.g., Na+ or Cl−). In addition, functionally similar transporters or splice variants with different regulatory profiles will optimize pH physiology and solute transport under various conditions or within subcellular domains. Such optimization will depend on activated signaling pathways and transporter expression profiles. In this review, we will summarize and discuss both well-known and more recently identified regulators of the Slc4 proteins. Some of these regulators include traditional second messengers, lipids, binding proteins, autoregulatory domains, and less conventional regulators. The material presented will provide insight into the diversity and physiological significance of multiple members within the Slc4 gene family. PMID:26124722

  2. Saturn Plasma Sources and Associated Transport Processes

    NASA Astrophysics Data System (ADS)

    Blanc, M.; Andrews, D. J.; Coates, A. J.; Hamilton, D. C.; Jackman, C. M.; Jia, X.; Kotova, A.; Morooka, M.; Smith, H. T.; Westlake, J. H.

    2015-10-01

    This article reviews the different sources of plasma for Saturn's magnetosphere, as they are known essentially from the scientific results of the Cassini-Huygens mission to Saturn and Titan. At low and medium energies, the main plasma source is the H2O cloud produced by the "geyser" activity of the small satellite Enceladus. Impact ionization of this cloud occurs to produce on the order of 100 kg/s of fresh plasma, a source which dominates all the other ones: Titan (which produces much less plasma than anticipated before the Cassini mission), the rings, the solar wind (a poorly known source due to the lack of quantitative knowledge of the degree of coupling between the solar wind and Saturn's magnetosphere), and the ionosphere. At higher energies, energetic particles are produced by energy diffusion and acceleration of lower energy plasma produced by the interchange instabilities induced by the rapid rotation of Saturn, and possibly, for the highest energy range, by contributions from the CRAND process acting inside Saturn's magnetosphere. Discussion of the transport and acceleration processes acting on these plasma sources shows the importance of rotation-induced radial transport and energization of the plasma, and also shows how much the unexpected planetary modulation of essentially all plasma parameters of Saturn's magnetosphere remains an unexplained mystery.

  3. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much_lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  4. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  5. Coupled transport processes in semipermeable media

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1990-03-01

    The thermodynamics of irreversible processes leads to nonlinear governing equations for direct and coupled mass transport processes. Analytical solutions of linearized versions of these equations can be used to verify numerical solutions of the nonlinear equations under conditions such that nonlinear terms are relatively small. This report presents derivations of the analytical solutions for one-dimensional and axisymmetric geometries. 7 refs.

  6. Modeling of Active Transmembrane Transport in a Mixture Theory Framework

    PubMed Central

    Ateshian, Gerard A.; Morrison, Barclay; Hung, Clark T.

    2010-01-01

    This study formulates governing equations for active transport across semi-permeable membranes within the framework of the theory of mixtures. In mixture theory, which models the interactions of any number of fluid and solid constituents, a supply term appears in the conservation of linear momentum to describe momentum exchanges among the constituents. In past applications, this momentum supply was used to model frictional interactions only, thereby describing passive transport processes. In this study, it is shown that active transport processes, which impart momentum to solutes or solvent, may also be incorporated in this term. By projecting the equation of conservation of linear momentum along the normal to the membrane, a jump condition is formulated for the mechano-electrochemical potential of fluid constituents which is generally applicable to nonequilibrium processes involving active transport. The resulting relations are simple and easy to use, and address an important need in the membrane transport literature. PMID:20213212

  7. Lagrangian coherent structures and plasma transport processes

    NASA Astrophysics Data System (ADS)

    Falessi, M. V.; Pegoraro, F.; Schep, T. J.

    2015-10-01

    > A dynamical system framework is used to describe transport processes in plasmas embedded in a magnetic field. For periodic systems with one degree of freedom, the Poincaré map provides a splitting of the phase space into regions where particles have different kinds of motion: periodic, quasi-periodic or chaotic. The boundaries of these regions are transport barriers, i.e. a trajectory cannot cross such boundaries throughout the evolution of the system. Lagrangian coherent structures generalize this method to systems with the most general time dependence, splitting the phase space into regions with different qualitative behaviours. This leads to the definition of finite-time transport barriers, i.e. trajectories cannot cross the barrier for a finite amount of time. This methodology can be used to identify fast recirculating regions in the dynamical system and to characterize the transport between them.

  8. Coupled transport processes in semipermeable media

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1990-04-01

    A numerical simulator has been developed to investigate the effects of coupled processes on heat and mass transport in semipermeable media. The governing equations on which the simulator is based were derived using the thermodynamics of irreversible processes. The equations are nonlinear and have been solved numerically using the n-dimensional Newton's method. As an example of an application, the numerical simulator has been used to investigate heat and solute transport in the vicinity of a heat source buried in a saturated clay-like medium, in part to study solute transport in bentonite packing material surrounding a nuclear waste canister. The coupled processes considered were thermal filtration, thermal osmosis, chemical osmosis and ultrafiltration. In the simulations, heat transport by coupled processes was negligible compared to heat conduction, but pressure and solute migration were affected. Solute migration was retarded relative to the uncoupled case when only chemical osmosis was considered. When both chemical osmosis and thermal osmosis were included, solute migration was enhanced. 18 refs., 20 figs.

  9. Gravity-dependent transport in industrial processes

    NASA Technical Reports Server (NTRS)

    Ostrach, Simon; Kamotani, Yasuhiro

    1994-01-01

    Gravity-dependent transport phenomena in various industrial processes are investigated in order to address a broader range of microgravity phenomena and to develop new applications of microgravity. A number of important topics are identified and analyzed in detail. The present article describes results on coating flow, zeolite growth, and rotating electrochemical system.

  10. Gravity-Dependent Transport in Industrial Processes

    NASA Technical Reports Server (NTRS)

    Ostrach, Simon; Kamotani, Yasuhiro

    1996-01-01

    Gravity dependent transport phenomena in various industrial processes are investigated in order to indicate new directions for micro-gravity research that enhance the commercial success of the space program. The present article describes the commercialization possibilities of such topics associated with physicochemical transport phenomena. The topics are: coating flow, rotating electrochemical system, and convection in low Plandtl number fluids. The present study is directed to understand these phenomena, and to develop a knowledge base for their applications with emphasis to a micro-gravity environment.

  11. Transport processes of radiopharmaceuticals and -modulators

    PubMed Central

    2011-01-01

    Radiotherapy and radiology have been indispensable components in cancer care for many years. The detection limit of small tumor foci as well as the development of radio-resistance and severe side effects towards normal tissues led to the development of strategies to improve radio-diagnostic and -therapeutic approaches by pharmaceuticals. The term "radiopharmaceutical" has been used for drugs labeled with radioactive tracers for therapy or diagnosis. In addition, drugs have been described to sensitize tumor cells to radiotherapy (radiosensitizers) or to protect normal tissues from detrimental effects of radiation (radioprotectors). The present review summarizes recent concepts on the transport of radiopharmaceuticals, radiosensitizers, and radioprotectors in cells and tissues, e.g. by ATP-binding cassette transporters such as P-glycoprotein. Strengths and weaknesses of current strategies to improve transport-based processes are discussed. PMID:21645349

  12. The Human Transporter Associated with Antigen Processing

    PubMed Central

    Corradi, Valentina; Singh, Gurpreet; Tieleman, D. Peter

    2012-01-01

    The human transporter associated with antigen processing (TAP) is a member of the ATP binding cassette (ABC) transporter superfamily. TAP plays an essential role in the antigen presentation pathway by translocating cytosolic peptides derived from proteasomal degradation into the endoplasmic reticulum lumen. Here, the peptides are loaded into major histocompatibility class I molecules to be in turn exposed at the cell surface for recognition by T-cells. TAP is a heterodimer formed by the association of two half-transporters, TAP1 and TAP2, with a typical ABC transporter core that consists of two nucleotide binding domains and two transmembrane domains. Despite the availability of biological data, a full understanding of the mechanism of action of TAP is limited by the absence of experimental structures of the full-length transporter. Here, we present homology models of TAP built on the crystal structures of P-glycoprotein, ABCB10, and Sav1866. The models represent the transporter in inward- and outward-facing conformations that could represent initial and final states of the transport cycle, respectively. We described conserved regions in the endoplasmic reticulum-facing loops with a role in the opening and closing of the cavity. We also identified conserved π-stacking interactions in the cytosolic part of the transmembrane domains that could explain the experimental data available for TAP1-Phe-265. Electrostatic potential calculations gave structural insights into the role of residues involved in peptide binding, such as TAP1-Val-288, TAP2-Cys-213, TAP2-Met-218. Moreover, these calculations identified additional residues potentially involved in peptide binding, in turn verified with replica exchange simulations performed on a peptide bound to the inward-facing models. PMID:22700967

  13. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

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

    1990-07-01

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

  14. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  15. The "independence principle" in the processes of water transport.

    PubMed Central

    Hernández, J A; Fischbarg, J

    1994-01-01

    The processes of membrane transport exhibiting permeability coefficients depending on the species activities do not obey the "independence principle" and are assumed to take place by a mechanism of discrete nature, analyzable by a kinetic formalism. In this article, we study the dependence of the osmotic permeability coefficient on the water activities, from the steady-state analysis of a kinetic model of single-file water transport that simultaneously incorporates the vacancy-mediated and "knock-on" mechanisms into the state diagram. In particular, we study the relation between the near-equilibrium osmotic permeability (Pe) and the equilibrium water activity of the compartments (w). The analysis and numerical calculations performed for a simple case of the model show that, for values of the parameters consistent with experimental data, Pe exhibits only a small variation with w within the physiological range in the majority of the situations considered here. It is not possible to predict, from the study of these simple models, whether more complicated kinetic diagrams of water transport may be characterized by permeability coefficients with a more evident dependence on the water activities. Nevertheless, the results obtained here suggest that, for the case of physiological water pores, the analysis of the kinetic dependence of the permeability coefficients on the water activities may not yield evidence pointing to a discrete nature for the transport process. PMID:7529582

  16. Coupled transport processes in semipermeable media

    SciTech Connect

    Carnahan, C.L.; Jacobsen, J.S.

    1990-04-01

    The thermodynamics of irreversible processes (TTIP) is used to derive governing equations and phenomenological equations for transport processes and chemical reactions in water-saturated semipermeable media. TTIP is based on three fundamental postulates. The first postulate, the assumption of local equilibrium, allows the formulation of balance equations for entropy. These equations are the bases for the derivation of governing equations for the thermodynamic variables, temperature, pressure, and composition. The governing equations involve vector fluxes of heat and mass and scalar rates of chemical reactions; in accordance with the second postulate of TTIP, these fluxes and rates are related, respectively, to all scalar driving forces (gradients of thermodynamic variables) acting within the system. The third postulate of TTIP states equality (the Onsager reciprocal relations) between certain of the phenomenological coefficients relating forces and fluxes. The description by TTIP of a system undergoing irreversible processes allows consideration of coupled transport processes such as thermal osmosis, chemical osmosis, and ultrafiltration. The coupled processes can make significant contributions to flows of mass and energy in slightly permeable, permselective geological materials such as clays and shales.

  17. Measurement of action spectra of light-activated processes

    NASA Astrophysics Data System (ADS)

    Ross, Justin; Zvyagin, Andrei V.; Heckenberg, Norman R.; Upcroft, Jacqui; Upcroft, Peter; Rubinsztein-Dunlop, Halina H.

    2006-01-01

    We report on a new experimental technique suitable for measurement of light-activated processes, such as fluorophore transport. The usefulness of this technique is derived from its capacity to decouple the imaging and activation processes, allowing fluorescent imaging of fluorophore transport at a convenient activation wavelength. We demonstrate the efficiency of this new technique in determination of the action spectrum of the light mediated transport of rhodamine 123 into the parasitic protozoan Giardia duodenalis.

  18. Ratchet transport powered by chiral active particles

    PubMed Central

    Ai, Bao-quan

    2016-01-01

    We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a ‘sea’ of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters (the chirality, the height of the barrier, the self-propulsion speed and the packing fraction) at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles. PMID:26795952

  19. Ratchet transport powered by chiral active particles

    NASA Astrophysics Data System (ADS)

    Ai, Bao-Quan

    2016-01-01

    We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a ‘sea’ of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters (the chirality, the height of the barrier, the self-propulsion speed and the packing fraction) at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles.

  20. Ratchet transport powered by chiral active particles.

    PubMed

    Ai, Bao-quan

    2016-01-01

    We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a 'sea' of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters (the chirality, the height of the barrier, the self-propulsion speed and the packing fraction) at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles. PMID:26795952

  1. Elucidating the role of transport processes in leaf glucosinolate distribution.

    PubMed

    Madsen, Svend Roesen; Olsen, Carl Erik; Nour-Eldin, Hussam Hassan; Halkier, Barbara Ann

    2014-11-01

    In Arabidopsis (Arabidopsis thaliana), a strategy to defend its leaves against herbivores is to accumulate glucosinolates along the midrib and at the margin. Although it is generally assumed that glucosinolates are synthesized along the vasculature in an Arabidopsis leaf, thereby suggesting that the margin accumulation is established through transport, little is known about these transport processes. Here, we show through leaf apoplastic fluid analysis and glucosinolate feeding experiments that two glucosinolate transporters, GTR1 and GTR2, essential for long-distance transport of glucosinolates in Arabidopsis, also play key roles in glucosinolate allocation within a mature leaf by effectively importing apoplastically localized glucosinolates into appropriate cells. Detection of glucosinolates in root xylem sap unambiguously shows that this transport route is involved in root-to-shoot glucosinolate allocation. Detailed leaf dissections show that in the absence of GTR1 and GTR2 transport activity, glucosinolates accumulate predominantly in leaf margins and leaf tips. Furthermore, we show that glucosinolates accumulate in the leaf abaxial epidermis in a GTR-independent manner. Based on our results, we propose a model for how glucosinolates accumulate in the leaf margin and epidermis, which includes symplasmic movement through plasmodesmata, coupled with the activity of putative vacuolar glucosinolate importers in these peripheral cell layers. PMID:25209984

  2. Conditions and processes affecting radionuclide transport

    USGS Publications Warehouse

    Simmons, Ardyth M.; Neymark, Leonid A.

    2012-01-01

    Understanding of unsaturated-zone transport is based on laboratory and field-scale experiments. Fractures provide advective transport pathways. Sorption and matrix diffusion may contribute to retardation of radionuclides. Conversely, sorption onto mobile colloids may enhance radionuclide transport.

  3. Stochastic steps in secondary active sugar transport.

    PubMed

    Adelman, Joshua L; Ghezzi, Chiara; Bisignano, Paola; Loo, Donald D F; Choe, Seungho; Abramson, Jeff; Rosenberg, John M; Wright, Ernest M; Grabe, Michael

    2016-07-01

    Secondary active transporters, such as those that adopt the leucine-transporter fold, are found in all domains of life, and they have the unique capability of harnessing the energy stored in ion gradients to accumulate small molecules essential for life as well as expel toxic and harmful compounds. How these proteins couple ion binding and transport to the concomitant flow of substrates is a fundamental structural and biophysical question that is beginning to be answered at the atomistic level with the advent of high-resolution structures of transporters in different structural states. Nonetheless, the dynamic character of the transporters, such as ion/substrate binding order and how binding triggers conformational change, is not revealed from static structures, yet it is critical to understanding their function. Here, we report a series of molecular simulations carried out on the sugar transporter vSGLT that lend insight into how substrate and ions are released from the inward-facing state of the transporter. Our simulations reveal that the order of release is stochastic. Functional experiments were designed to test this prediction on the human homolog, hSGLT1, and we also found that cytoplasmic release is not ordered, but we confirmed that substrate and ion binding from the extracellular space is ordered. Our findings unify conflicting published results concerning cytoplasmic release of ions and substrate and hint at the possibility that other transporters in the superfamily may lack coordination between ions and substrate in the inward-facing state. PMID:27325773

  4. Chill Down Process of Hydrogen Transport Pipelines

    NASA Technical Reports Server (NTRS)

    Mei, Renwei; Klausner, James

    2006-01-01

    A pseudo-steady model has been developed to predict the chilldown history of pipe wall temperature in the horizontal transport pipeline for cryogenic fluids. A new film boiling heat transfer model is developed by incorporating the stratified flow structure for cryogenic chilldown. A modified nucleate boiling heat transfer correlation for cryogenic chilldown process inside a horizontal pipe is proposed. The efficacy of the correlations is assessed by comparing the model predictions with measured values of wall temperature in several azimuthal positions in a well controlled experiment by Chung et al. (2004). The computed pipe wall temperature histories match well with the measured results. The present model captures important features of thermal interaction between the pipe wall and the cryogenic fluid, provides a simple and robust platform for predicting pipe wall chilldown history in long horizontal pipe at relatively low computational cost, and builds a foundation to incorporate the two-phase hydrodynamic interaction in the chilldown process.

  5. Space transportation main engine cycle assessment process

    NASA Technical Reports Server (NTRS)

    Mcconnaughey, H. V.; Lyles, G. M.

    1991-01-01

    The Advanced Launch System (ALS) program selection process for a space transportation main engine (STME) power cycle is described in terms of the methodology employed. Low cost, robustness, and high reliability are the primary parameters for engine choice, suggesting simplicity of design and efficient fabrication methods as the crucial characteristics. An evaluation methodology is developed based on the Pugh (1981) process and the King (1989) matrices. The cycle configurations considered are the gas generator (GG), the closed expander, and the open expander. The cycle assessment team determined that the GG cycle is favored by most cycle discriminators, based on an assessment of the characteristics in terms of ALS goals. The lower development risk of the GG-cycle STME is consistent with the goals of the ALS program in terms of reliability and cost efficiency.

  6. 23 CFR 450.208 - Coordination of planning process activities.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Coordination of planning process activities. 450.208 Section 450.208 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH PLANNING ASSISTANCE AND STANDARDS Statewide Transportation Planning and Programming § 450.208 Coordination of planning process activities. (a)...

  7. IDENTIFICATION AND EVALUATION OF FUNDAMENTAL TRANSPORT AND TRANSFORMATION PROCESS MODELS

    EPA Science Inventory

    Chemical fate models require explicit algorithms for computing the effects of transformation and transport processes on the spatial and temporal distribution of chemical concentrations. Transport processes in aquatic systems are driven by physical characteristics on the system an...

  8. Development of novel active transport membrande devices

    SciTech Connect

    Laciak, D.V.

    1994-11-01

    Air Products has undertaken a research program to fabricate and evaluate gas separation membranes based upon promising ``active-transport`` (AT) materials recently developed in our laboratories. Active Transport materials are ionic polymers and molten salts which undergo reversible interaction or reaction with ammonia and carbon dioxide. The materials are useful for separating these gases from mixtures with hydrogen. Moreover, AT membranes have the unique property of possessing high permeability towards ammnonia and carbon dioxide but low permeability towards hydrogen and can thus be used to permeate these components from a gas stream while retaining hydrogen at high pressure.

  9. Health Impacts of Active Transportation in Europe.

    PubMed

    Rojas-Rueda, David; de Nazelle, Audrey; Andersen, Zorana J; Braun-Fahrländer, Charlotte; Bruha, Jan; Bruhova-Foltynova, Hana; Desqueyroux, Hélène; Praznoczy, Corinne; Ragettli, Martina S; Tainio, Marko; Nieuwenhuijsen, Mark J

    2016-01-01

    Policies that stimulate active transportation (walking and bicycling) have been related to heath benefits. This study aims to assess the potential health risks and benefits of promoting active transportation for commuting populations (age groups 16-64) in six European cities. We conducted a health impact assessment using two scenarios: increased cycling and increased walking. The primary outcome measure was all-cause mortality related to changes in physical activity level, exposure to fine particulate matter air pollution with a diameter <2.5 μm, as well as traffic fatalities in the cities of Barcelona, Basel, Copenhagen, Paris, Prague, and Warsaw. All scenarios produced health benefits in the six cities. An increase in bicycle trips to 35% of all trips (as in Copenhagen) produced the highest benefits among the different scenarios analysed in Warsaw 113 (76-163) annual deaths avoided, Prague 61 (29-104), Barcelona 37 (24-56), Paris 37 (18-64) and Basel 5 (3-9). An increase in walking trips to 50% of all trips (as in Paris) resulted in 19 (3-42) deaths avoided annually in Warsaw, 11(3-21) in Prague, 6 (4-9) in Basel, 3 (2-6) in Copenhagen and 3 (2-4) in Barcelona. The scenarios would also reduce carbon dioxide emissions in the six cities by 1,139 to 26,423 (metric tonnes per year). Policies to promote active transportation may produce health benefits, but these depend of the existing characteristics of the cities. Increased collaboration between health practitioners, transport specialists and urban planners will help to introduce the health perspective in transport policies and promote active transportation. PMID:26930213

  10. Health Impacts of Active Transportation in Europe

    PubMed Central

    Rojas-Rueda, David; de Nazelle, Audrey; Andersen, Zorana J.; Braun-Fahrländer, Charlotte; Bruha, Jan; Bruhova-Foltynova, Hana; Desqueyroux, Hélène; Praznoczy, Corinne; Ragettli, Martina S.; Tainio, Marko; Nieuwenhuijsen, Mark J.

    2016-01-01

    Policies that stimulate active transportation (walking and bicycling) have been related to heath benefits. This study aims to assess the potential health risks and benefits of promoting active transportation for commuting populations (age groups 16–64) in six European cities. We conducted a health impact assessment using two scenarios: increased cycling and increased walking. The primary outcome measure was all-cause mortality related to changes in physical activity level, exposure to fine particulate matter air pollution with a diameter <2.5 μm, as well as traffic fatalities in the cities of Barcelona, Basel, Copenhagen, Paris, Prague, and Warsaw. All scenarios produced health benefits in the six cities. An increase in bicycle trips to 35% of all trips (as in Copenhagen) produced the highest benefits among the different scenarios analysed in Warsaw 113 (76–163) annual deaths avoided, Prague 61 (29–104), Barcelona 37 (24–56), Paris 37 (18–64) and Basel 5 (3–9). An increase in walking trips to 50% of all trips (as in Paris) resulted in 19 (3–42) deaths avoided annually in Warsaw, 11(3–21) in Prague, 6 (4–9) in Basel, 3 (2–6) in Copenhagen and 3 (2–4) in Barcelona. The scenarios would also reduce carbon dioxide emissions in the six cities by 1,139 to 26,423 (metric tonnes per year). Policies to promote active transportation may produce health benefits, but these depend of the existing characteristics of the cities. Increased collaboration between health practitioners, transport specialists and urban planners will help to introduce the health perspective in transport policies and promote active transportation. PMID:26930213

  11. Vertical transport processes in unconfined aquifers

    NASA Astrophysics Data System (ADS)

    Ostendorf, David W.; Reckhow, David A.; Popielarczyk, David J.

    1989-02-01

    We derive simple two-dimensional mathematical models describing the unsteady transport of conservative contaminants through an unconfined aquifer with a gently sloping aquiclude subject to advection, recharge, and vertical dispersion. The inclusion of vertical transport terms permits the proper nonreactive analysis of closed and open chemical systems, with the latter allowing dispersion of volatile constituents across the water table. These systems exhibit conservative and pseudoreactive behavior respectively when the pollution is analyzed on a depth-integrated basis, as is common in present one-dimensional models of groundwater contamination. Vertical and longitudinal chloride and total inorganic carbon observations at the well-documented Babylon, Long Island sanitary landfill plume are used to calibrate and test the analyses with a modest level of accuracy, using the vertical dispersivity as a calibration factor in this testing process. The parameter is important in the determination of reaeration rates across the water table and nutrient mixing from below in the related problem of biological transformations near the free surface.

  12. Howard Brenner's Legacy for Biological Transport Processes

    NASA Astrophysics Data System (ADS)

    Nitsche, Johannes

    2014-11-01

    This talk discusses the manner in which Howard Brenner's theoretical contributions have had, and long will have, strong and direct impact on the understanding of transport processes occurring in biological systems. His early work on low Reynolds number resistance/mobility coefficients of arbitrarily shaped particles, and particles near walls and in pores, is an essential component of models of hindered diffusion through many types of membranes and tissues, and convective transport in microfluidic diagnostic systems. His seminal contributions to macrotransport (coarse-graining, homogenization) theory presaged the growing discipline of multiscale modeling. For biological systems they represent the key to infusing diffusion models of a wide variety of tissues with a sound basis in their microscopic structure and properties, often over a hierarchy of scales. Both scientific currents are illustrated within the concrete context of diffusion models of drug/chemical diffusion through the skin. This area of theory, which is key to transdermal drug development and risk assessment of chemical exposure, has benefitted very directly from Brenner's contributions. In this as in other areas, Brenner's physicochemical insight, mathematical virtuosity, drive for fully justified analysis free of ad hoc assumptions, quest for generality, and impeccable exposition, have consistently elevated the level of theoretical understanding and presentation. We close with anecdotes showing how his personal qualities and warmth helped to impart high standards of rigor to generations of grateful research students. Authors are Johannes M. Nitsche, Ludwig C. Nitsche and Gerald B. Kasting.

  13. Fluid transport by active elastic membranes

    NASA Astrophysics Data System (ADS)

    Evans, Arthur A.; Lauga, Eric

    2011-09-01

    A flexible membrane deforming its shape in time can self-propel in a viscous fluid. Alternatively, if the membrane is anchored, its deformation will lead to fluid transport. Past work in this area focused on situations where the deformation kinematics of the membrane were prescribed. Here we consider models where the deformation of the membrane is not prescribed, but instead the membrane is internally forced. Both the time-varying membrane shape and the resulting fluid motion result then from a balance between prescribed internal active stresses, internal passive resistance, and external viscous stresses. We introduce two specific models for such active internal forcing: one where a distribution of active bending moments is prescribed, and one where active inclusions exert normal stresses on the membrane by pumping fluid through it. In each case, we asymptotically calculate the membrane shape and the fluid transport velocities for small forcing amplitudes, and recover our results using scaling analysis.

  14. Prebiotic activation processes.

    NASA Technical Reports Server (NTRS)

    Lohrmann, R.; Orgel, L. E.

    1973-01-01

    Questions regarding the combination of amino acids and ribonucleotides to polypeptides and polynucleotides are investigated. Each of the reactions considered occurs in the solid state in plausible prebiotic conditions. Together they provide the basis for a unified scheme of amino acid and nucleotide activation. Urea, imidazole and Mg(++) are essential catalytic components of the reaction mixtures. However, these compounds could probably be replaced by other organic molecules.

  15. Campylobacter and Salmonella in broiler processingtransport through chill

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When market age broilers are transported to processing plants, feces from individual birds in a Campylobacter positive flock can contaminate transport containers (1). Feces, and therefore Campylobacter, is deposited on the floor surface of transport cages. When placed in soiled transport cages pr...

  16. A Thermodynamic Description of Active Transport

    NASA Astrophysics Data System (ADS)

    Kjelstrup, S.; Rubi, J. M.; Bedeaux, D.

    We present a solution to problems that were raised in the 1960s: How can the vectorial ion flux couple to the scalar energy of the reaction of ATP to ADP and P, to give active transport of the ion; i.e. transport against its chemical potential? And, is it possible, on thermodynamic grounds to obtain non-linear flux force relations for this transport? Using non-equilibrium thermodynamics (NET) on the stochastic (mesoscopic) level, we explain how the second law of thermodynamics gives a basis for the description of active transport of Ca2+ by the Ca-ATPase. Coupling takes place at the surface, because the symmetry of the fluxes changes here. The theory gives the energy dissipated as heat during transport and reaction. Experiments are defined to determine coupling coefficients. We propose that the coefficients for coupling between chemical reaction, ion flux and heat flux are named thermogenesis coefficients. They are all probably significant. We discuss that the complete set of coefficients can explain slippage in molecular pumps as well as thermogenesis that is triggered by a temperature jump.

  17. Transport Processes in High Temperature QCD Plasmas

    NASA Astrophysics Data System (ADS)

    Hong, Juhee

    The transport properties of high temperature QCD plasmas can be described by kinetic theory based on the Boltzmann equation. At a leading-log approximation, the Boltzmann equation is reformulated as a Fokker-Planck equation. First, we compute the spectral densities of Tµν and Jµ by perturbing the system with weak gravitational and electromagnetic fields. The spectral densities exhibit a smooth transition from free-streaming quasi-particles to hydrodynamics. This transition is analyzed with hydrodynamics and diffusion equation up to second order. We determine all of the first and second order transport coefficients which characterize the linear response in the hydrodynamic regime. Second, we simulate the wake of a heavy quark moving through the plasmas. At long distances, the energy density and flux distributions show sound waves and a diffusion wake. The kinetic theory calculations based on the Boltzmann equation at weak coupling are compared to the strong coupling results given by the AdS/CFT correspondence. By using the hard-thermal-loop effective theory, we determine the photon emission rate at next-to-leading order (NLO), i.e., at order g2mD /T. There are three mechanisms which contribute to the leading-order photon emission: (2 ↔ 2) elastic scatterings, (1 ↔ 2) collinear bremsstrahlung, and (1 ↔ 1) quark-photon conversion due to soft fermion exchange. At NLO, these three mechanisms are not completely independent. When the transverse momentum between quark and photon becomes soft, the Compton scattering with a soft gluon reduces to wide-angle bremsstrahlung. Similarly, bremsstrahlung reduces to the quark-photon conversion process when the photon carries most of the incoming momentum. Therefore, the rates should be matched to determine the wide-angle NLO correction. Collinear bremsstrahlung can be accounted for by solving an integral

  18. Active transport of vesicles in neurons is modulated by mechanical tension

    NASA Astrophysics Data System (ADS)

    Ahmed, Wylie W.; Saif, Taher A.

    2014-03-01

    Effective intracellular transport of proteins and organelles is critical in cells, and is especially important for ensuring proper neuron functionality. In neurons, most proteins are synthesized in the cell body and must be transported through thin structures over long distances where normal diffusion is insufficient. Neurons transport subcellular cargo along axons and neurites through a stochastic interplay of active and passive transport. Mechanical tension is critical in maintaining proper function in neurons, but its role in transport is not well understood. To this end, we investigate the active and passive transport of vesicles in Aplysia neurons while changing neurite tension via applied strain, and quantify the resulting dynamics. We found that tension in neurons modulates active transport of vesicles by increasing the probability of active motion, effective diffusivity, and induces a retrograde bias. We show that mechanical tension modulates active transport processes in neurons and that external forces can couple to internal (subcellular) forces and change the overall transport dynamics.

  19. NEURONAL ACTIVITY REGULATES GLUTAMATE TRANSPORTER DYNAMICS IN DEVELOPING ASTROCYTES

    PubMed Central

    Benediktsson, A.M.; Marrs, G.S.; Tu, J.C.; Worley, P.F.; Rothstein, J.D.; Bergles, D.E.; Dailey, M.E.

    2011-01-01

    Glutamate transporters maintain a low ambient level of glutamate in the CNS and shape the activation of glutamate receptors at synapses. Nevertheless, the mechanisms that regulate the trafficking and localization of transporters near sites of glutamate release are poorly understood. Here we examined the subcellular distribution and dynamic remodeling of the predominant glutamate transporter GLT-1 (EAAT2) in developing hippocampal astrocytes. Immunolabeling revealed that endogenous GLT-1 is concentrated into discrete clusters along branches of developing astrocytes that were apposed preferentially to synapsin-1 positive synapses. GFP-GLT-1 fusion proteins expressed in astrocytes also formed distinct clusters that lined the edges of astrocyte processes, as well as the tips of filopodia and spine-like structures. Time-lapse 3D confocal imaging in tissue slices revealed that GFP-GLT-1 clusters were dynamically remodeled on a timescale of minutes. Some transporter clusters moved within developing astrocyte branches as filopodia extended and retracted, while others maintained stable positions at the tips of spine-like structures. Blockade of neuronal activity with tetrodotoxin reduced both the density and perisynaptic localization of GLT-1 clusters. Conversely, enhancement of neuronal activity increased the size of GLT-1 clusters and their proximity to synapses. Together, these findings indicate that neuronal activity influences both the organization of glutamate transporters in developing astrocyte membranes and their position relative to synapses. PMID:22052455

  20. Use of boundary fluxes when simulating solute transport with the MODFLOW ground-water transport process

    USGS Publications Warehouse

    Konikow, L.F.; Hornberger, G.Z.

    2003-01-01

    This report describes modifications to a U.S. Geological Survey (USGS) threedimensional solute-transport model (MODFLOWGWT), which is incorporated into the USGS MODFLOW ground-water model as the Ground- Water Transport (GWT) Process. The modifications improve the capability of MODFLOW-GWT to accurately simulate solute transport in simulations that represent a nonzero flux across an aquifer boundary. In such situations, the new Boundary Flux Package (BFLX) will allow the user flexibility to assign the flux to specific cell faces, although that flexibility is limited for certain types of fluxes (such as recharge and evapotranspiration, which can only be assigned to the top face if either is to be represented as a boundary flux). The approach is consistent with that used in the MODPATH model. The application of the BFLX Package was illustrated using a test case in which the Lake Package was active. The results using the BFLX Package showed noticeably higher magnitudes of velocity in the cells adjacent to the lake than previous results without the BFLX Package. Consequently, solute was transported slightly faster through the lake-aquifer system when the BFLX Package is active. However, the overall solute distributions did not differ greatly from simulations made without using the BFLX Package.

  1. Overview of medium heterogeneity and transport processes

    SciTech Connect

    Tsang, Y.; Tsang, C.F.

    1993-11-01

    Medium heterogeneity can have significant impact on the behavior of solute transport. Tracer breakthrough curves from transport in a heterogeneous medium are distinctly different from that in a homogeneous porous medium. Usually the shape of the breakthrough curves are highly non-symmetrical with a fast rise at early times and very long tail at late times, and often, they consist of multiple peaks. Moreover, unlike transport in a homogeneous medium where the same transport parameters describe the entire medium, transport through heterogeneous media gives rise to breakthrough curves which have strong spatial dependence. These inherent characteristics of transport in heterogeneous medium present special challenge to the performance assessment of a potential high level nuclear waste repository with respect to the possible release of radio nuclides to the accessible environment. Since an inherently desirable site characteristic for a waste repository is that flow and transport should be slow, then transport measurements in site characterization efforts will necessarily be spatially small and temporally short compare to the scales which are of relevance to performance assessment predictions. In this paper we discuss the role of medium heterogeneity in site characterization and performance assessment. Our discussion will be based on a specific example of a 3D heterogeneous stochastic model of a site generally similar to, the Aespoe Island, the site of the Hard Rock Laboratory in Southern Sweden. For our study, alternative 3D stochastic fields of hydraulic conductivities conditioned on ``point`` measurements shall be generated. Results of stochastic flow and transport simulations would be used to address the issues of (1) the relationship of tracer breakthrough with the structure of heterogeneity, and (2) the inference from small scale testing results to large scale and long term predictions.

  2. Active and passive calcium transport systems in plant cells

    SciTech Connect

    Sze, H.

    1990-01-01

    The ability to change cytoplasmic Ca{sup 2+} levels ((Ca{sup 2+})) by cells has made this cation a key regulator of many biological processes. Cytoplasmic (Ca{sup 2+}) is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic (Ca{sup 2+}) and active Ca{sup 2+} transport systems that lower cytosolic (Ca{sup 2+}). The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells. 10 figs., 2 tabs.

  3. Active and passive calcium transport systems in plant cells

    SciTech Connect

    Sze, H.

    1991-01-01

    The ability to change cytoplasmic Ca{sup 2+} levels ((Ca{sup 2+})) by cells has made this cation a key regulator of many biological processes. Cytoplasmic (Ca{sup 2+}) is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic (Ca{sup 2+}) and active Ca{sup 2+} transport systems that lower cytosolic (Ca{sup 2+}). The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells.

  4. Representing Microbial Processes in Environmental Reactive Transport Models

    NASA Astrophysics Data System (ADS)

    van Cappellen, P.

    2009-04-01

    The activities of microorganisms profoundly impact the chemical structure and biogeochemical dynamics of surface and subsurface environments. In the context of reactive transport modeling, a major challenge is to derive, calibrate and validate rate expressions for microbially-mediated reaction processes. This challenge is best met by combining field observations, laboratory experiments and theory. In my presentation, I will illustrate such an integrated approach for the case of microbial respiration in aquatic sediments. Topics that will be dealt with are model consistency, interpretation of experimental data, bioenergetics, transient behavior and model performance.

  5. Calcium and sodium transport processes in patients with cystic fibrosis 2. Mg2+- dependent, Ca2+ ATPase activity in fibroblast membrane preparations from cystic fibrosis patients and controls.

    PubMed

    Katz, S

    1978-03-01

    Mg2+-dependent Ca2+-ATPase activity was determined in membrane preparations of fibroblasts grown from skin biopsies of cystic fibrosis patients and age-matched controls. This enzyme was stimulated by increasing free calcium concentrations with an apparent Kdiss for calcium of approximately 45 micron. Although there was a great deal of variation in Ca2+-ATPase activity observed between individual strains, there was a significant decrease in the maximal activation of the Ca2+-ATPase in membrane preparations of fibroblasts obtained from cystic fibrosis patients compared to the controls (P less than 0.05). This observation indicates that decreased Ca2+-ATPase activity is a generalized phenomenon in cystic fibrosis found in more than one cell-type. This decrease in Ca2+-ATPase activity may have a number of implications that may explain some of the manifestations of the disease. PMID:148720

  6. Advocacy for active transport: advocate and city council perspectives

    PubMed Central

    2010-01-01

    Background Effective advocacy is an important part of efforts to increase population participation in physical activity. Research about effective health advocacy is scarce, however, the health sector can learn from the experiences and knowledge of community advocates and those who are on the receiving end of this advocacy. The aim of this study is to explore advocacy for active transport from the perspectives of community advocates and representatives from City councils. Methods Cycling and walking advocates were identified from the local contact list of Cycling Advocates Network and Living Streets Aotearoa. Semi-structured telephone interviews were conducted with cycle and walking advocates from throughout New Zealand. Advocates also nominated a suitable council officer at their local City council to be interviewed. Interviews were recorded and transcribed and categories of responses for each of the questions created. Results Several processes were used by advocates to engage with council staff, including formal council submissions, meetings, stakeholder forums and partnership in running community events promoting active transport. Several other agencies were identified as being influential for active transport, some as potential coalition partners and others as potential adversaries. Barriers to improving conditions for active transport included a lack of funding, a lack of will-power among either council staff or councillors, limited council staff capacity (time or training) and a culture of providing infrastructure for motor vehicles instead of people. Several suggestions were made about how the health sector could contribute to advocacy efforts, including encouraging political commitment, engaging the media, communicating the potential health benefits of active transport to the general public and being role models in terms of personal travel mode choice and having workplaces that support participation in active transport. Conclusions There is potential for the

  7. An active matter analysis of intracellular Active Transport

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Chen, Kejia; Bae, Sung Chul; Granick, Steve

    2012-02-01

    Tens of thousands of fluorescence-based trajectories at nm resolution have been analyzed, regarding active transport along microtubules in living cells. The following picture emerges. Directed motion to pre-determined locations is certainly an attractive idea, but cannot be pre-programmed as to do so would sacrifice adaptability. The polarity of microtubules is inadequate to identify these directions in cells, and no other mechanism is currently known. We conclude that molecular motors carry cargo through disordered intracellular microtubule networks in a statistical way, with loud cellular ``noise'' both in directionality and speed. Programmed random walks describe how local 1D active transport traverses crowded cellular space efficiently, rapidly, minimizing the energy waste that would result from redundant activity. The mechanism of statistical regulation is not yet understood, however.

  8. Quantification of chemical transport processes from soil to surface runoff

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although there is a conceptual understanding on processes governing chemical transport from soil to surface runoff, there are little literature and research results actually quantifying these individual processes. We developed a laboratory flow cell and experimental procedures to quantify chemical ...

  9. Large-Scale Stratospheric Transport Processes

    NASA Technical Reports Server (NTRS)

    Plumb, R. Alan

    2001-01-01

    The paper discusses the following: 1. The Brewer-Dobson circulation: tropical upwelling. 2. Mixing into polar vortices. 3. The latitudinal structure of "age" in the stratosphere. 4. The subtropical "tracer edges". 5. Transport in the lower troposphere. 6. Tracer modeling during SOLVE. 7. 3D modeling of "mean age". 8. Models and measurements II.

  10. Organic Semiconductors: A Molecular Picture of the Charge-Transport and Energy-Transport Processes.

    NASA Astrophysics Data System (ADS)

    Brédas, Jean-Luc

    2007-03-01

    Conjugated organic oligomer and polymer materials are being increasingly considered for their incorporation as the active semiconductor elements in devices such as photo-voltaic cells, light-emitting diodes, or field-effects transistors. In the operation of these devices, electron-transfer and energy-transfer processes play a key role, for instance in the form of charge transport (in the bulk or across interfaces), energy transport, charge separation, or charge recombination [1]. Here, we provide a theoretical description of electron-transfer phenomena based on electron-transfer theory, which allows us to provide a molecular, chemically-oriented understanding. In this presentation, we focus on the parameters that impact the mobility of charge carriers [2], that is the electronic coupling within chains and between adjacent chains and the reorganization energy of the chains upon ionization. Materials under study include conjugated oligomers such as oligoacenes, oligothiophene-acenes, oligothiophenes, and oligothienacenes. [1] J.L. Br'edas, D. Beljonne, V. Coropceanu, and J. Cornil, ``Charge-Transfer and Energy-Transfer Processes in pi-Conjugated Oligomers and Polymers'', Chemical Reviews, 104, 4971-5004 (2004). [2] V. Coropceanu, J. Cornil, D.A. da Silva Filho, Y. Olivier, R. Silbey, and J.L. Br'edas, ``Charge Transport in Organic Semiconductors'', Chemical Reviews, 107, xxx (2007).

  11. Activation product transport in fusion reactors. [RAPTOR

    SciTech Connect

    Klein, A.C.

    1983-01-01

    Activated corrosion and neutron sputtering products will enter the coolant and/or tritium breeding material of fusion reactor power plants and experiments and cause personnel access problems. Radiation levels around plant components due to these products will cause difficulties with maintenance and repair operations throughout the plant. Similar problems are experienced around fission reactor systems. The determination of the transport of radioactive corrosion and neutron sputtering products through the system is achieved using the computer code RAPTOR. This code calculates the mass transfer of a number of activation products based on the corrosion and sputtering rates through the system, the deposition and release characteristics of various plant components, the neturon flux spectrum, as well as other plant parameters. RAPTOR assembles a system of first order linear differential equations into a matrix equation based upon the reactor system parameters. Included in the transfer matrix are the deposition and erosion coefficients, and the decay and activation data for the various plant nodes and radioactive isotopes. A source vector supplies the corrosion and neutron sputtering source rates. This matrix equation is then solved using a matrix operator technique to give the specific activity distribution of each radioactive species throughout the plant. Once the amount of mass transfer is determined, the photon transport due to the radioactive corrosion and sputtering product sources can be evaluated, and dose rates around the plant components of interest as a function of time can be determined. This method has been used to estimate the radiation hazards around a number of fusion reactor system designs.

  12. Active transporters as enzymes: an energetic framework applied to major facilitator superfamily and ABC importer systems.

    PubMed

    Shilton, Brian H

    2015-04-15

    Active membrane transporters are dynamic molecular machines that catalyse transport across a membrane by coupling solute movement to a source of energy such as ATP or a secondary ion gradient. A central question for many active transporters concerns the mechanism by which transport is coupled to a source of energy. The transport process and associated energetic coupling involve conformational changes in the transporter. For efficient transport, the conformational changes must be tightly regulated and they must link energy use to movement of the substrate across the membrane. The present review discusses active transport using the well-established energetic framework for enzyme-mediated catalysis. In particular, membrane transport systems can be viewed as ensembles consisting of low-energy and high-energy conformations. The transport process involves binding interactions that selectively stabilize the higher energy conformations, and in this way promote conformational changes in the system that are coupled to decreases in free energy and substrate translocation. The major facilitator superfamily of secondary active transporters is used to illustrate these ideas, which are then be expanded to primary active transport mediated by ABC (ATP-binding cassette) import systems, with a focus on the well-studied maltose transporter. PMID:25837849

  13. Absorption of ipratropium and l-carnitine into the pulmonary circulation of the ex-vivo rat lung is driven by passive processes rather than active uptake by OCT/OCTN transporters.

    PubMed

    Al-Jayyoussi, Ghaith; Price, Daniel F; Kreitmeyr, Katharina; Keogh, John P; Smith, Mathew W; Gumbleton, Mark; Morris, Christopher J

    2015-12-30

    The organic cation transporters OCT and OCTN have been reported to play a significant role in the cellular uptake of substrates within in vitro lung cells. However, no studies to date have investigated the effect of these transporters upon transepithelial absorption of substrates into the pulmonary circulation. We investigated the contribution of OCT and OCTN transporters to total pulmonary absorption of l-carnitine and the anti-muscarinic drug, ipratropium, across an intact isolated perfused rat lung (IPRL). The results obtained from the IPRL were contrasted with active transport in vitro using three human pulmonary cell lines and primary rat alveolar epithelial cells. Ex-vivo studies showed that OCT/OCTN transporters do not play a role in the overall pulmonary absorption of l-carnitine or ipratropium, as evidenced by the effect of chemical inhibition of these transporters upon pulmonary absorption. In contrast, in vitro studies showed that OCT/OCTN transporters play a significant role in cellular accumulation of substrates with preferential uptake of ipratropium by OCTs, and of l-carnitine uptake by OCTNs. The results show that in vitro uptake studies cannot be predictive of airway to blood absorption in vivo. Nevertheless, localised submucosal pulmonary concentrations of inhaled drugs and their pulmonary pharmacodynamic profiles may be influenced by OCT/OCTN transport activity. PMID:26475971

  14. Large-scale Atmospheric Transport Processes

    NASA Technical Reports Server (NTRS)

    Plumb, R. Alan

    2004-01-01

    Continuing earlier work, we continued an investigation of the seasonal behavior of the edges of the stratospheric surf zone. These edges form a barrier between the rapidly mixed surf zone and the relatively isolated tropics. In collaboration with Dr Lynn Sparling at GSFC, we used a statistical analysis of HALOE and CLAES trace gas data from UARS to identify and locate these edges during each UARS observing period. We found that the edges on both sides of the equator are present all year (a fact that is important for conceptual models of stratospheric transport), though that on the summer side of the equator is much less sharp than the winter edge. The edges migrate seasonally into the summer hemisphere. Their location also shows influence of the QBO, together with the SAO at higher altitudes. Comparisons with effective diffusivities, and the edge locations, suggest that the edge is sustained by surf zone entrainment during winter, but by the residual circulation during summer.

  15. Large-scale Stratospheric Transport Processes

    NASA Technical Reports Server (NTRS)

    Plumb, R. Alan

    2003-01-01

    The PI has undertaken a theoretical analysis of the existence and nature of compact tracer-tracer relationships of the kind observed in the stratosphere, augmented with three-dimensional model simulations of stratospheric tracers (the latter being an extension of modeling work the group did during the SOLVE experiment). This work achieves a rigorous theoretical basis for the existence and shape of these relationships, as well as a quantitative theory of their width and evolution, in terms of the joint tracer-tracer PDF distribution. A paper on this work is almost complete and will soon be submitted to Rev. Geophys. We have analyzed lower stratospheric water in simulations with an isentropic-coordinate version of the MATCH transport model which we recently helped to develop. The three-dimensional structure of lower stratospheric water, in particular, attracted our attention: dry air is, below about 400K potential temperature, localized in the regions of the west Pacific and equatorial South America. We have been analyzing air trajectories to determine how air passes through the tropopause cold trap. This work is now being completed, and a paper will be submitted to Geophys. Res. Lett. before the end of summer. We are continuing to perform experiments with the 'MATCH' CTM, in both sigma- and entropy-coordinate forms. We earlier found (in collaboration with Dr Natalie Mahowald, and as part of an NSF-funded project) that switching to isentropic coordinates made a substantial improvement to the simulation of the age of stratospheric air. We are now running experiments with near-tropopause sources in both versions of the model, to see if and to what extent the simulation of stratosphere-troposphere transport is dependent on the model coordinate. Personnel Research is supervised by the PI, Prof. Alan Plumb. Mr William Heres conducts the tracer modeling work and performs other modeling tasks. Two graduate students, Ms Irene Lee and Mr Michael Ring, have been participating

  16. Universality in Transport Processes of Unconventional Superconductors

    NASA Astrophysics Data System (ADS)

    Sauls, J. A.

    1997-03-01

    I will review recent work on the theory of charge and energy transport in unconventional superconductors, with applications to d-wave models for the cuprates and the heavy fermion superconductors.(M.J. Graf, S.-K. Yip, D. Rainer and J.A. Sauls, Phys. Rev. B,53), 15147 (1996). Comparisons with recent experiments will be presented.(L. Taillefer, this conference.) I will discuss the key features of the pairing symmetry, Fermi surface and excitation spectrum that are reflected in the electrical, thermal and acoustic response functions at very low temperatures, where transport is limited by electron scattering from random defects. Certain eigenvalues of the thermal conductivity and acoustic attenuation tensors are shown to be universal at low temperature, kB T<< γ, where γ is the bandwidth of impurity-induced bound states in the superconducting phase. The components of the electrical and thermal conductivity also obey a Wiedemann-Franz law with the Lorenz ratio, L(T)=κ/σ T, given by the Sommerfeld value of L_S=(π^2/3)(k_B/e)^2 for k_BT<<γ. For intermediate temperatures the Lorenz ratio deviates significantly from L_S, and is strongly dependent on the scattering cross section, and qualitatively different for resonant vs. nonresonant scattering. Nonuniversal results for the acoustic response, arising from nonvanishing impurity scattering vertex corrections, are shown to be direct tests of spontaneously broken time-reversal symmetry by the pairing state.(M.J. Graf, et al., this conference.)

  17. Modeling Nonequilibrium Flow and Transport Processes Using HYDRUS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate process-based modeling of nonequilibrium water flow and solute transport remains a major challenge in vadose zone hydrology. The objective of this paper is to describe a wide range of nonequilibrium flow and transport modeling approaches available within the latest version of the HYDRUS-1D ...

  18. Active sodium transport and the electrophysiology of rabbit colon.

    PubMed

    Schultz, S G; Frizzell, R A; Nellans, H N

    1977-05-12

    The electrophysiologic properties of rabbit colonic epithelial cells were investigated employing microelectrode techniques. Under open-circuit conditions, the transepithelial electrical potential difference (PD) averaged 20 mV, serosa positive, and the intracellular electrical potential (psimc) averaged -32 mV, cell interior negative with respect to the mucosal solution; under short-circuit conditions, psimc averaged -46 mV. The addition of amiloride to the mucosal solution abolishes the transepithelial PD and active Na transport, and psimc is hyperpolarized to an average value of -53 mV. These results indicate that Na entry into the mucosal cell is a conductive process which, normally, depolarized psimc. The data obtained were interpreted using a double-membrane equivalent electrical circuit model of the "active Na transport pathway" involving two voltage-independent electromotive forces (emf's) and two voltage-independent resistances arrayed in series. Our observations are consistent with the notions that: (a) The emf's and resistances across the mucosal and baso-lateral membranes are determined predominantly by the emf (64 mV) and resistance of the Na entry process and the emf (53 mV) and resistance of the process responsible for active Na extrusion across the baso-lateral membranes: that is, the electrophysiological properties of the cell appear to be determined solely by the properties and processes responsible for transcellular active Na transport. The emf of the Na entry process is consistent with the notion that the Na activity in the intracellular transport pool is approximately one-tenth that in the mucosal solution or about 14 mM. (b) In the presence of amiloride, the transcellular conductance is essentially abolished and the total tissue conductance is the result of ionic diffusion through paracellular pathways. (c) The negative intracellular potential (with respect to the mucosal solution) is due primarily to the presence of a low resistance

  19. Processes of Salt Transport in Disturbed Streams

    NASA Astrophysics Data System (ADS)

    Chitrakar, S.; Miller, S. N.; Caffrey, P. A.; Stern, J.

    2013-12-01

    The extraction of coal bed methane natural gas involves removal of large amount of ground/Coal Bed Methane (CBM) water which is commonly discharged to surface-water drainages or constructed reservoirs. The extraction of large volume of water and its disposal on soil surface not only lowers the water table but also potentially accelerate soil erosions, contaminate surface water resources, and alter the natural flows. Due to the difference in quality and quantity between the surface discharge and disposed CBM water, this management strategy potentially poses threats to quality of surface water and soil. CBM discharge water typically contains high concentrations of sodium and low concentrations of calcium and magnesium, resulting in high sodium adsorption ratio (SAR). Similarly, it also contains high concentration of other ions which could results in increasing salt concentrations. Our study area is in the Atlantic Rim development area of the Muddy Creek, SE of Wyoming, a tributary to Colorado River, where significant development of CBM wells is ongoing. Since Muddy Creek is part of the Upper Colorado River, the greatest concern is its potential to contribute to surface water quality (primarily salinity) impairment downstream. However, very few studies have made efforts to assess the water quality in this particular region. The alteration of stream water quality in this region is still not fully understood if it due to CBM water discharge or via soil/water interactions, erosion, and sediment transport. Efforts are being made to identify crucial water quality parameters such as SAR and EC along with the quantification of solute/salt loadings at both CBM discharge fed streams and natural streams at different seasons to distinguish effect of CBM discharge on water quality. We have been continuously monitoring water quality on monthly basis and discharge measurement on daily basis at sampling sites that are placed to discriminate CBM fed streams and natural streams. The

  20. Associations between street connectivity and active transportation

    PubMed Central

    2010-01-01

    Background Past studies of associations between measures of the built environment, particularly street connectivity, and active transportation (AT) or leisure walking/bicycling have largely failed to account for spatial autocorrelation of connectivity variables and have seldom examined both the propensity for AT and its duration in a coherent fashion. Such efforts could improve our understanding of the spatial and behavioral aspects of AT. We analyzed spatially identified data from Los Angeles and San Diego Counties collected as part of the 2001 California Health Interview Survey. Results Principal components analysis indicated that ~85% of the variance in nine measures of street connectivity are accounted for by two components representing buffers with short blocks and dense nodes (PRIN1) or buffers with longer blocks that still maintain a grid like structure (PRIN2). PRIN1 and PRIN2 were positively associated with active transportation (AT) after adjustment for diverse demographic and health related variables. Propensity and duration of AT were correlated in both Los Angeles (r = 0.14) and San Diego (r = 0.49) at the zip code level. Multivariate analysis could account for the correlation between the two outcomes. After controlling for demography, measures of the built environment and other factors, no spatial autocorrelation remained for propensity to report AT (i.e., report of AT appeared to be independent among neighborhood residents). However, very localized correlation was evident in duration of AT, particularly in San Diego, where the variance of duration, after accounting for spatial autocorrelation, was 5% smaller within small neighborhoods (~0.01 square latitude/longitude degrees = 0.6 mile diameter) compared to within larger zip code areas. Thus a finer spatial scale of analysis seems to be more appropriate for explaining variation in connectivity and AT. Conclusions Joint analysis of the propensity and duration of AT behavior and an explicitly

  1. A Reactive Transport Simulator for Biogeochemical Processes in Subsurface System

    2003-04-01

    BIOGEOCHEM is a Fortran code that mumerically simulates the coupled processes of solute transport, microbial population dynamics, microbial metabolism, and geochemical reactions. The potential applications of the code include, but not limited to, (a) sensitivity and uncertainty analyses for assessing the impact of microbial activity on subsurface geochemical systems; (b) extraction of biogeochemical parameter values from field observations or laboratory measurements, (c) helping to design and optimize laboratory biogeochemical experiments, and (d) data integration. Methodmore » of Solution: A finite difference method and a Newton-Raphson technique are used to solve a set of coupled nonlinear partial differential equations and algebraic equations. Practical Application: Environmental analysis, bioremediation performance assessments of radioactive or non-radioactive wase disposal, and academic research.« less

  2. Transport processes in biological systems: Tumoral cells and human brain

    NASA Astrophysics Data System (ADS)

    Lucia, Umberto

    2014-01-01

    The entropy generation approach has been developed for the analysis of complex systems, with particular regards to biological systems, in order to evaluate their stationary states. The entropy generation is related to the transport processes related to exergy flows. Moreover, cancer can be described as an open complex dynamic and self-organizing system. Consequently, it is used as an example useful to evaluate the different thermo-chemical quantities of the transport processes in normal and in tumoral cells systems.

  3. Nucleocytoplasmic transport of ribosomes in a eukaryotic system: Is there a facilitated transport process

    SciTech Connect

    Khanna-Gupta, A.; Ware, V.C. )

    1989-03-01

    The authors have examined the kinetics of the process by which ribosomes are exported from the nucleus to the cytoplasm using Xenopus laevis oocytes microinjected into the germinal vesicle with radiolabeled ribosomes or ribosomal subunits from X. laevis, Tetrahymena thermophila, or Escherichia coli. Microinjected eukaryotic mature ribosomes are redistributed into the oocyte cytoplasm by an apparent carrier-mediated transport process that exhibits saturation kinetics as increasing amounts of ribosomes are injected. T. thermophila ribosomes are competent to traverse the Xenopus nuclear envelope, suggesting that the basic mechanism underlying ribosome transport is evolutionarily conserved. Microinjected E. coli ribosomes are not transported in this system, indicating that prokaryotic ribosomes lack the signals required for transport. Surprisingly, coinjected small (40S) and large (60S) subunits from T. thermophila are transported significantly faster than individual subunits. These observations support a facilitated transport model for the translocation of ribosomal subunits as separate units across the nuclear envelope whereby the transport rate of 60S or 40S subunits is enhanced by the presence of the partner subunit. Although the basic features of the transport mechanism have been preserved through evolution, other aspects of the process may be mediated through species-specific interactions. They hypothesize that a species-specific nuclear 40S-60S subunit association may expedite the transport of individual subunits across the nuclear envelope.

  4. Understanding the transport processes in polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Cheah, May Jean

    Polymer electrolyte membrane (PEM) fuel cells are energy conversion devices suitable for automotive, stationary and portable applications. An engineering challenge that is hindering the widespread use of PEM fuel cells is the water management issue, where either a lack of water (resulting in membrane dehydration) or an excess accumulation of liquid water (resulting in fuel cell flooding) critically reduces the PEM fuel cell performance. The water management issue is addressed by this dissertation through the study of three transport processes occurring in PEM fuel cells. Water transport within the membrane is a combination of water diffusion down the water activity gradient and the dragging of water molecules by protons when there is a proton current, in a phenomenon termed electro-osmotic drag, EOD. The impact of water diffusion and EOD on the water flux across the membrane is reduced due to water transport resistance at the vapor/membrane interface. The redistribution of water inside the membrane by EOD causes an overall increase in the membrane resistance that regulates the current and thus EOD, thereby preventing membrane dehydration. Liquid water transport in the PEM fuel cell flow channel was examined at different gas flow regimes. At low gas Reynolds numbers, drops transitioned into slugs that are subsequently pushed out of the flow channel by the gas flow. The slug volume is dependent on the geometric shape, the surface wettability and the orientation (with respect to gravity) of the flow channel. The differential pressure required for slug motion primarily depends on the interfacial forces acting along the contact lines at the front and the back of the slug. At high gas Reynolds number, water is removed as a film or as drops depending on the flow channel surface wettability. The shape of growing drops at low and high Reynolds number can be described by a simple interfacial energy minimization model. Under flooding conditions, the fuel cell local current

  5. Transport induced by mean-eddy interaction: II. Analysis of transport processes

    NASA Astrophysics Data System (ADS)

    Ide, Kayo; Wiggins, Stephen

    2015-03-01

    We present a framework for the analysis of transport processes resulting from the mean-eddy interaction in a flow. The framework is based on the Transport Induced by the Mean-Eddy Interaction (TIME) method presented in a companion paper (Ide and Wiggins, 2014) [1]. The TIME method estimates the (Lagrangian) transport across stationary (Eulerian) boundaries defined by chosen streamlines of the mean flow. Our framework proceeds after first carrying out a sequence of preparatory steps that link the flow dynamics to the transport processes. This includes the construction of the so-called "instantaneous flux" as the Hovmöller diagram. Transport processes are studied by linking the signals of the instantaneous flux field to the dynamical variability of the flow. This linkage also reveals how the variability of the flow contributes to the transport. The spatio-temporal analysis of the flux diagram can be used to assess the efficiency of the variability in transport processes. We apply the method to the double-gyre ocean circulation model in the situation where the Rossby-wave mode dominates the dynamic variability. The spatio-temporal analysis shows that the inter-gyre transport is controlled by the circulating eddy vortices in the fast eastward jet region, whereas the basin-scale Rossby waves have very little impact.

  6. Elemental processes of transport and energy conversion in Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Angelopoulos, Vassilis

    In the last 5 years observations from several missions and ground based observatories have honed in on the most elemental aspects of flux transport and energy conversion. Dipolarization fronts and their counterpart in the distant magnetotail "anti-dipolarization" fronts, which together are refered to herein as "reconnection fronts", usher the recently reconnected flux tubes from the near-Earth X-points and in the process convert magnetic energy to particle energy and wave radiation. On the tailward side they are responsible for plasmoid formation and acceleration. On the earthward side they result in elemental substorm current wedges or wedglets, which were initially postulated from ground observations alone. Recent observations have revealed how the interaction of wedgelets and the inner magnetosphere takes place. Questions remain with regards to the physics of the energy transfer process from global magnetic energy to local heating and waves, and with regards to the initiation of the X-point activations in space. Observations indicate that the latter may be induced by polar cap or dayside activity, suggesting a direct link between dayside reconnection and nightside phenomena. The likely causal sequence of events and open questions in light of these recent observations, and the field's outlook in anticipation of upcoming coordinated observations from the international Heliophysics System Observatory will be discussed.

  7. Air pollution exposure: An activity pattern approach for active transportation

    NASA Astrophysics Data System (ADS)

    Adams, Matthew D.; Yiannakoulias, Nikolaos; Kanaroglou, Pavlos S.

    2016-09-01

    In this paper, we demonstrate the calculation of personal air pollution exposure during trips made by active transportation using activity patterns without personal monitors. We calculate exposure as the inhaled dose of particulate matter 2.5 μg or smaller. Two modes of active transportation are compared, and they include cycling and walking. Ambient conditions are calculated by combining mobile and stationary monitoring data in an artificial neural network space-time model. The model uses a land use regression framework and has a prediction accuracy of R2 = 0.78. Exposure is calculated at 10 m or shorter intervals during the trips using inhalation rates associated with both modes. The trips are children's routes between home and school. The average dose during morning cycling trips was 2.17 μg, during morning walking trips was 3.19 μg, during afternoon cycling trips was 2.19 μg and during afternoon walking trips was 3.23 μg. The cycling trip dose was significantly lower than the walking trip dose. The air pollution exposure during walking or cycling trips could not be strongly predicted by either the school or household ambient conditions, either individually or in combination. Multiple linear regression models regressing both the household and school ambient conditions against the dose were only able to account for, at most, six percent of the variance in the exposure. This paper demonstrates that incorporating activity patterns when calculating exposure can improve the estimate of exposure compared to its calculation from ambient conditions.

  8. Modelling bedload transport events using an inhomogeneous gamma process

    NASA Astrophysics Data System (ADS)

    Hurley, M. A.

    1992-10-01

    Monitored sequences of bedload transport events in two small gravel-bedded trout streams are described. To model the event timings, the inhomogeneous gamma process, with the special case of the Poisson process, are introduced, in which the baseline intensity is related to a linear regression combination of covariates. These may be time-varying covariates, such as seasonal cycles, covariates specific to an individual process or covariates common to more than one process. It is shown that the maximum likelihood estimates of the regression parameters may be obtained by an iterative least-squares procedure. The procedure is demonstrated by application to the bedload transport event sequences.

  9. A Simple Laboratory Exercise Illustrating Active Transport in Yeast Cells.

    ERIC Educational Resources Information Center

    Stambuk, Boris U.

    2000-01-01

    Describes a simple laboratory activity illustrating the chemiosmotic principles of active transport in yeast cells. Demonstrates the energy coupling mechanism of active a-glucoside uptake by Saccaromyces cerevisiae cells with a colorimetric transport assay using very simple equipment. (Contains 22 references.) (Author/YDS)

  10. Processing and transport of environmental virus samples.

    PubMed Central

    Dahling, D R; Wright, B A

    1984-01-01

    Poliovirus-seeded tap water, conditioned with MgCl2 and passed through virus-adsorbing filters, gave better poliovirus recovery than water identically treated but conditioned with AlCl3. Elution of several filter types with beef extract yielded higher recoveries than did elution with glycine. Seeded samples filtered through various filters and stored showed considerable virus loss in 2 days when stored at 4 degrees C, whereas those stored at -70 degrees C gave stable virus recovery up to 4 days. Additionally, the use of antifoam during the elution process reduced foaming and increased virus recovery by 28%. PMID:6331312

  11. Thermodynamically coupled mass transport processes in a saturated clay

    SciTech Connect

    Carnahan, C.L.

    1984-11-01

    Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimensional transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 references, 8 figures, 1 table.

  12. Linking stochastic sediment transport to physical processes (Invited)

    NASA Astrophysics Data System (ADS)

    Jerolmack, D. J.; Martin, R.; Paola, C.; Reitz, M. D.; Schumer, R.

    2010-12-01

    Intermittent transport is the rule rather than the exception in sedimentary systems. Avalanching dynamics in granular flows is known to produce stochastic transport fluctuations over a wide range of scales - for example, the well known power-law distributions of landslide magnitudes. Similar stochastic dynamics can occur in multi-phase flows, e.g., bedload transport in rivers. A generalized theoretical framework for understanding stochastic transport is lacking. A pragmatic alternative is the stochastic processes approach: using (fractional) advection-diffusion equations, conditioned with measured statistics from a real system, to make future predictions about transport. Linking the macroscopic statistics described by such models to the microscopic physics of sediment transport will require a new statistical mechanics approach. We propose to begin by delineating generic categories of transport mechanics - universality classes - and determining their statistical signatures through theory and experiment. A first separation may be drawn between periodic and aperiodic transport fluctuations. Periodic transport fluctuations have been observed in both sand piles and river delta experiments, and appear to arise under conditions of a well-defined transport threshold (e.g., an angle of repose) and limited dissipation. Under these conditions, inertia overwhelms system heterogeneity and gives rise to periodic oscillations having a characteristic magnitude. Aperiodic transport fluctuations often imply a strong control of system heterogeneity, and/or significant dissipation or friction capable of “breaking up” sediment pulses. For example, varying soil properties give rise to a range of critical failure slopes for landslides. Transitions in the dominant transport process from small to large time or space scales are expected to result in transitions in scaling. Bedload transport is super-diffusive at short timescales because of correlated motion due to particle momentum. At

  13. Vortical ciliary flows actively enhance mass transport in reef corals

    PubMed Central

    Shapiro, Orr H.; Fernandez, Vicente I.; Garren, Melissa; Guasto, Jeffrey S.; Debaillon-Vesque, François P.; Kramarsky-Winter, Esti; Vardi, Assaf; Stocker, Roman

    2014-01-01

    The exchange of nutrients and dissolved gasses between corals and their environment is a critical determinant of the growth of coral colonies and the productivity of coral reefs. To date, this exchange has been assumed to be limited by molecular diffusion through an unstirred boundary layer extending 1–2 mm from the coral surface, with corals relying solely on external flow to overcome this limitation. Here, we present direct microscopic evidence that, instead, corals can actively enhance mass transport through strong vortical flows driven by motile epidermal cilia covering their entire surface. Ciliary beating produces quasi-steady arrays of counterrotating vortices that vigorously stir a layer of water extending up to 2 mm from the coral surface. We show that, under low ambient flow velocities, these vortices, rather than molecular diffusion, control the exchange of nutrients and oxygen between the coral and its environment, enhancing mass transfer rates by up to 400%. This ability of corals to stir their boundary layer changes the way that we perceive the microenvironment of coral surfaces, revealing an active mechanism complementing the passive enhancement of transport by ambient flow. These findings extend our understanding of mass transport processes in reef corals and may shed new light on the evolutionary success of corals and coral reefs. PMID:25192936

  14. Particle Tracking Model and Abstraction of Transport Processes

    SciTech Connect

    B. Robinson

    2000-04-07

    The purpose of the transport methodology and component analysis is to provide the numerical methods for simulating radionuclide transport and model setup for transport in the unsaturated zone (UZ) site-scale model. The particle-tracking method of simulating radionuclide transport is incorporated into the FEHM computer code and the resulting changes in the FEHM code are to be submitted to the software configuration management system. This Analysis and Model Report (AMR) outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the unsaturated zone at Yucca Mountain. In addition, methods for determining colloid-facilitated transport parameters are outlined for use in the Total System Performance Assessment (TSPA) analyses. Concurrently, process-level flow model calculations are being carrier out in a PMR for the unsaturated zone. The computer code TOUGH2 is being used to generate three-dimensional, dual-permeability flow fields, that are supplied to the Performance Assessment group for subsequent transport simulations. These flow fields are converted to input files compatible with the FEHM code, which for this application simulates radionuclide transport using the particle-tracking algorithm outlined in this AMR. Therefore, this AMR establishes the numerical method and demonstrates the use of the model, but the specific breakthrough curves presented do not necessarily represent the behavior of the Yucca Mountain unsaturated zone.

  15. Role of glutathione transport processes in kidney function

    SciTech Connect

    Lash, Lawrence H. . E-mail: l.h.lash@wayne.edu

    2005-05-01

    The kidneys are highly dependent on an adequate supply of glutathione (GSH) to maintain normal function. This is due, in part, to high rates of aerobic metabolism, particularly in the proximal tubules. Additionally, the kidneys are potentially exposed to high concentrations of oxidants and reactive electrophiles. Renal cellular concentrations of GSH are maintained by both intracellular synthesis and transport from outside the cell. Although function of specific carriers has not been definitively demonstrated, it is likely that multiple carriers are responsible for plasma membrane transport of GSH. Data suggest that the organic anion transporters OAT1 and OAT3 and the sodium-dicarboxylate 2 exchanger (SDCT2 or NaDC3) mediate uptake across the basolateral plasma membrane (BLM) and that the organic anion transporting polypeptide OATP1 and at least one of the multidrug resistance proteins mediate efflux across the brush-border plasma membrane (BBM). BLM transport may be used pharmacologically to provide renal proximal tubular cells with exogenous GSH to protect against oxidative stress whereas BBM transport functions physiologically in turnover of cellular GSH. The mitochondrial GSH pool is derived from cytoplasmic GSH by transport into the mitochondrial matrix and is mediated by the dicarboxylate and 2-oxoglutarate exchangers. Maintenance of the mitochondrial GSH pool is critical for cellular and mitochondrial redox homeostasis and is important in determining susceptibility to chemically induced apoptosis. Hence, membrane transport processes are critical to regulation of renal cellular and subcellular GSH pools and are determinants of susceptibility to cytotoxicity induced by oxidants and electrophiles.

  16. Transporting Radioactive Waste: An Engineering Activity. Grades 5-12.

    ERIC Educational Resources Information Center

    HAZWRAP, The Hazardous Waste Remedial Actions Program.

    This brochure contains an engineering activity for upper elementary, middle school, and high school students that examines the transportation of radioactive waste. The activity is designed to inform students about the existence of radioactive waste and its transportation to disposal sites. Students experiment with methods to contain the waste and…

  17. Particle Tracking Model and Abstraction of Transport Processes

    SciTech Connect

    B. Robinson

    2004-10-21

    The purpose of this report is to document the abstraction model being used in total system performance assessment (TSPA) model calculations for radionuclide transport in the unsaturated zone (UZ). The UZ transport abstraction model uses the particle-tracking method that is incorporated into the finite element heat and mass model (FEHM) computer code (Zyvoloski et al. 1997 [DIRS 100615]) to simulate radionuclide transport in the UZ. This report outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the UZ at Yucca Mountain. In addition, methods for determining and inputting transport parameters are outlined for use in the TSPA for license application (LA) analyses. Process-level transport model calculations are documented in another report for the UZ (BSC 2004 [DIRS 164500]). Three-dimensional, dual-permeability flow fields generated to characterize UZ flow (documented by BSC 2004 [DIRS 169861]; DTN: LB03023DSSCP9I.001 [DIRS 163044]) are converted to make them compatible with the FEHM code for use in this abstraction model. This report establishes the numerical method and demonstrates the use of the model that is intended to represent UZ transport in the TSPA-LA. Capability of the UZ barrier for retarding the transport is demonstrated in this report, and by the underlying process model (BSC 2004 [DIRS 164500]). The technical scope, content, and management of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Transport Model Report Integration'' (BSC 2004 [DIRS 171282]). Deviations from the technical work plan (TWP) are noted within the text of this report, as appropriate. The latest version of this document is being prepared principally to correct parameter values found to be in error due to transcription errors, changes in source data that were not captured in the report, calculation errors, and errors in interpretation of source data.

  18. Active transmembrane drug transport in microgravity: a validation study using an ABC transporter model

    PubMed Central

    Vaquer, Sergi; Cuyàs, Elisabet; Rabadán, Arnau; González, Albert; Fenollosa, Felip; de la Torre, Rafael

    2014-01-01

    Microgravity has been shown to influence the expression of ABC (ATP-Binding Cassette) transporters in bacteria, fungi and mammals, but also to modify the activity of certain cellular components with structural and functional similarities to ABC transporters. Changes in activity of ABC transporters could lead to important metabolic disorders and undesired pharmacological effects during spaceflights. However, no current means exist to study the functionality of these transporters in microgravity. To this end, a Vesicular Transport Assay ® (Solvo Biotechnology, Hungary) was adapted to evaluate multi-drug resistance-associated protein 2 (MRP2) trans-membrane estradiol-17-β-glucuronide (E17βG) transport activity, when activated by adenosine-tri-phosphate (ATP) during parabolic flights. Simple diffusion, ATP-independent transport and benzbromarone inhibition were also evaluated. A high accuracy engineering system was designed to perform, monitor and synchronize all procedures. Samples were analysed using a validated high sensitivity drug detection protocol. Experiments were performed in microgravity during parabolic flights, and compared to 1g on ground results using identical equipment and procedures in all cases. Our results revealed that sufficient equipment accuracy and analytical sensitivity were reached to detect transport activity in both gravitational conditions. Additionally, transport activity levels of on ground samples were within commercial transport standards, proving the validity of the methods and equipment used. MRP2 net transport activity was significantly reduced in microgravity, so was signal detected in simple diffusion samples. Ultra-structural changes induced by gravitational stress upon vesicle membranes or transporters could explain the current results, although alternative explanations are possible. Further research is needed to provide a conclusive answer in this regard. Nevertheless, the present validated technology opens new and

  19. Electro-osmotic transport in wet processing of textiles

    DOEpatents

    Cooper, J.F.

    1998-09-22

    Electro-osmotic (or electrokinetic) transport is used to efficiently force a solution (or water) through the interior of the fibers or yarns of textile materials for wet processing of textiles. The textile material is passed between electrodes that apply an electric field across the fabric. Used alone or in parallel with conventional hydraulic washing (forced convection), electro-osmotic transport greatly reduces the amount of water used in wet processing. The amount of water required to achieve a fixed level of rinsing of tint can be reduced, for example, to 1--5 lbs water per pound of fabric from an industry benchmark of 20 lbs water/lb fabric. 5 figs.

  20. Electro-osmotic transport in wet processing of textiles

    DOEpatents

    Cooper, John F.

    1998-01-01

    Electro-osmotic (or electrokinetic) transport is used to efficiently force a solution (or water) through the interior of the fibers or yarns of textile materials for wet processing of textiles. The textile material is passed between electrodes that apply an electric field across the fabric. Used alone or in parallel with conventional hydraulic washing (forced convection), electro-osmotic transport greatly reduces the amount of water used in wet processing. The amount of water required to achieve a fixed level of rinsing of tint can be reduced, for example, to 1-5 lbs water per pound of fabric from an industry benchmark of 20 lbs water/lb fabric.

  1. Kinetic and electromagnetic transport processes in toroidal devices

    SciTech Connect

    Moses, R.W.; Schoenberg, K.F.

    1990-01-01

    A brief review of transport processes in toroidal devices is presented. Particular attention is given to radial transport of power by the Poynting's vector and kinetic electron flow. This work is primarily focused on the Reversed Field Pinch (RFP) which holds the added complexity of a dynamo process that sustains poloidal current in the edge region, where the toroidal field is reversed. The experimental observation of superthermal unidirectional electrons in the plasma edge of ZT-40M and HBTX1C is noted, and the rapid, nonclassical ion heating in RFPs is taken account of. Radial transport parallel to fluctuating magnetic field lines is deemed a likely candidate for both electromagnetic and kinetic energy transport. Two models are discussed and compared. It is concluded that electromagnetic transport using a local Ohm's law best describes nonclassical ion heating, and the transport of kinetic energy by long mean free path electrons best represents the half-Maxwellian of electrons observed in the edge of several RFPs. A nonlocal Ohm's law is essential for the kinetic electron model. 18 refs.

  2. Active transport and accumulation of bicarbonate by a unicellular cyanobacterium.

    PubMed

    Miller, A G; Colman, B

    1980-09-01

    The rates of inorganic carbon accumulation and carbon fixation in light by the unicellular cyanobacterim Coccohloris peniocystis have been determined. Cells incubated in the light in medium containing H14CO3- were rapidly separated from the medium by centrifugation through silicone oil into a strongly basic terminating solution. Samples of these inactivated cells were assayed to determine total 14C accumulation, and acid-treated samples were assayed to determine 14C fixation. The rate of transport of inorganic into illuminated cells was faster than the rate of CO2 production in the medium from HCO3- dehydration. This evidence for HCO3- transport in these cells is in agreement with our previous results based upon measurements of photosynthetic O2 evolution. A substantial pool of inorganic carbon was bulit up within the cells presumably as HCO3- before the onset of the maximum rate of photosynthesis. Large accumulation ratios were observed, greater than 1,000 times the external HCO3- concentration. Accumulation did not occur in the dark and was greatly suppressed by the photosynthesis inhibitors 3-(3,4-dichlorophenyl)-1,1-dimethyl urea and 3-chloro-carbonylcyanide phenylhydrazone. These results indicate that the accumulation of inorganic carbon in these cells involves a light-dependent active transport process. PMID:6773925

  3. Heat transport in active harmonic chains

    SciTech Connect

    Zheng, Mei C.; Ellis, Fred M.; Kottos, Tsampikos; Fleischmann, Ragnar; Geisel, Theo; Prosen, Tomaz

    2011-08-15

    We show that a harmonic lattice model with amplifying and attenuating elements, when coupled to two thermal baths, exhibits unique heat transport properties. Some of these novel features include anomalous nonequilibrium steady-state heat currents, negative differential thermal conductance, as well as nonreciprocal heat transport. We find that when these elements are arranged in a PT-symmetric manner, the domain of existence of the nonequilibrium steady state is maximized. We propose an electronic experimental setup based on resistive-inductive-capacitive (RLC) transmission lines, where our predictions can be tested.

  4. Multi-fluid plasma modeling with Braginskii collisional transport processes

    NASA Astrophysics Data System (ADS)

    Ho, A.; Shumlak, U.; Miller, S. T.

    2015-11-01

    Magnetohydrodynamics (MHD) works well where transport processes are primarily advective. Extensions of the MHD model are capable of capturing some collisional phenomena such as electrical resistivity, which are important in systems with mean free paths less than the characteristic length. However, MHD models have difficulties resolving systems where the Debye length cannot be assumed to approach zero. These systems arise in low density, hot plasmas. By modeling the ions and electrons as distinct fluids, the 5-moment multi-fluid plasma model is able to capture these short-range transport processes that are not accounted for in MHD. To model the transport processes the Braginskii transport terms are added to the 5-moment model, which introduces viscosity, heat conduction, and binary species interactions. These transport properties are affected by strong magnetic fields, resulting in anisotropic collisional effects. The multi-fluid equations are evolved explicitly and are coupled with Maxwell's equations. This research extends the University of Washington's WARPXM code to include the Braginskii terms with the 5-moment multi-fluid plasma model. The implementation is validated against theoretical results from a Hartmann flow benchmark problem. This work is supported by a grant from the United States Air Force Office of Scientific Research.

  5. Background ozone in the southern Europe and Mediterranean area: influence of the transport processes.

    PubMed

    Cristofanelli, Paolo; Bonasoni, Paolo

    2009-05-01

    The troposphere is subject to continuous inputs, production and removal processes of ozone and its precursors from natural processes and human activities acting together within a very complex system. In order to assess the behaviour of background ozone in the Mediterranean area, a description of trends, seasonal and diurnal behaviours of free tropospheric ozone is provided. In the Mediterranean area and southern Europe the background tropospheric ozone concentration appears significantly affected by three main air mass transport processes: (i) transport of polluted air masses on regional and long-range scales, (ii) downward transport of stratospheric air masses, and (iii) transport of mineral dust from the Sahara desert. In this review of the literature of the last two decades, we present an overview of these phenomena, mainly monitored at high baseline mountain stations representative of background atmospheric conditions. PMID:18977575

  6. Application of active controls to civil transport aircraft

    NASA Technical Reports Server (NTRS)

    Taylor, L. W., Jr.

    1975-01-01

    The impact of active controls on civil transport aircraft and some of the complex problems involved are described. The approach taken by NASA as part of the Active Control Technology Program is discussed to integrate active controls in the conceptual design phase. It is shown that when handled correctly, active controls improve aircraft performance.

  7. Crystal structures of a polypeptide processing and secretion transporter.

    PubMed

    Lin, David Yin-wei; Huang, Shuo; Chen, Jue

    2015-07-23

    Bacteria secrete peptides and proteins to communicate, to poison competitors, and to manipulate host cells. Among the various protein-translocation machineries, the peptidase-containing ATP-binding cassette transporters (PCATs) are appealingly simple. Each PCAT contains two peptidase domains that cleave the secretion signal from the substrate, two transmembrane domains that form a translocation pathway, and two nucleotide-binding domains that hydrolyse ATP. In Gram-positive bacteria, PCATs function both as maturation proteases and exporters for quorum-sensing or antimicrobial polypeptides. In Gram-negative bacteria, PCATs interact with two other membrane proteins to form the type 1 secretion system. Here we present crystal structures of PCAT1 from Clostridium thermocellum in two different conformations. These structures, accompanied by biochemical data, show that the translocation pathway is a large α-helical barrel sufficient to accommodate small folded proteins. ATP binding alternates access to the transmembrane pathway and also regulates the protease activity, thereby coupling substrate processing to translocation. PMID:26201595

  8. Features, Events, and Processes in UZ Flow and Transport

    SciTech Connect

    P. Persoff

    2004-11-06

    The evaluation of impacts of potential volcanic eruptions on populations and facilities far in the future may involve detailed volcanological studies that differ from traditional hazards analyses. The proximity of Quaternary volcanoes to a proposed repository for disposal of the USA's high-level radioactive waste at Yucca Mountain, Nevada, has required in-depth study of probability and consequences of basaltic igneous activity. Because of the underground nature of the repository, evaluation of the potential effects of dike intrusion and interaction with the waste packages stored in underground tunnels (dnfts) as well as effects of eruption and ash dispersal have been important. These studies include analyses of dike propagation, dike-drift intersection, flow of magma into dnfts, heat and volcanic gas migration, atmospheric dispersal of tephra, and redistribution of waste-contaminated tephra by surficial processes. Unlike traditional volcanic hazards studies that focus on impacts on housing, transportation, communications, etc. (to name a small subset), the igneous consequences studies at Yucca Mountain have focused on evaluation of igneous impacts on nuclear waste packages and implications for enhanced radioactive dose on a hypothetical future ({le} 10000 yrs) local population. Potential exposure pathways include groundwater (affected by in-situ degradation of waste packages by igneous heat and corrosion) and inhalation, ingestion, and external exposure due to deposition and redistribution of waste-contaminated tephra.

  9. Reply to "Comment on `Generalized exclusion processes: Transport coefficients' "

    NASA Astrophysics Data System (ADS)

    Arita, Chikashi; Krapivsky, P. L.; Mallick, Kirone

    2016-07-01

    We reply to the Comment of Becker, Nelissen, Cleuren, Partoens, and Van den Broeck [Phys. Rev. E 93, 046101 (2016), 10.1103/PhysRevE.93.046101] on our article [Arita, Krapivsky, and Mallick, Phys. Rev. E 90, 052108 (2014), 10.1103/PhysRevE.90.052108] about the transport properties of a class of generalized exclusion processes.

  10. Transformation and Transport Processes of Nitrogen in Agricultural Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transformation and transport processes of nitrogen (N) in agricultural systems are discussed and information is provided on overall reservoir sizes for N. Nitrogen is ubiquitous in the environment and is required for the survival of all living things. It is also one of the most important essen...

  11. An Atomistic View on Fundamental Transport Processes on Metal Surfaces

    SciTech Connect

    Giesen, Margret

    2007-06-14

    In this lecture I present an introduction to the time-resolved observation of atomic transport processes on metal surfaces using scanning tunneling microscopy video sequences. The experimental data is analyzed using scaling law concepts known from statistical thermodynamics. I will present studies from metal surfaces in vacuum as well as in electrolyte.

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

    PubMed

    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. PMID:27472561

  13. Active urea transport by the skin of Bufo viridis: Amiloride- and phloretin-sensitive transport sites

    SciTech Connect

    Rapoport, J.; Abuful, A.; Chaimovitz, C.; Noeh, Z.; Hays, R.M. Albert Einstein College of Medicine, New York, NY )

    1988-09-01

    Urea is actively transported inwardly (J{sub i}) across the skin of the green toad Bufo viridis. J{sub i} is markedly enhanced in toads adapted to hypertonic saline. The authors studied urea transport across the skin of Bufo viridis under a variety of experimental conditions, including treatment with amiloride and phloretin, agents that inhibit urea permeability in the bladder of Bufo marinus. Amiloride (10{sup {minus}4} M) significantly inhibited J{sub i} in both adapted and unadapted animals and was unaffected by removal of sodium from the external medium. Phloretin (10{sup {minus}4} M) significantly inhibited J{sub i} in adapted animals by 23-46%; there was also a reduction in J{sub i} in unadapted toads at 10{sup {minus}4} and 5 {times} 10{sup {minus}4} M phloretin. A dose-response study revealed that the concentration of phloretin causing half-maximal inhibition (K{sub {1/2}}) was 5 {times} 10{sup {minus}4} M for adapted animals. J{sub i} was unaffected by the substitution of sucrose for Ringer solution or by ouabain. They conclude (1) the process of adaptation appears to involve an increase in the number of amiloride- and phloretin-inhibitable urea transport sites in the skin, with a possible increase in the affinity of the sites for phloretin; (2) the adapted skin resembles the Bufo marinus urinary bladder with respect to amiloride and phloretin-inhibitable sites; (3) they confirm earlier observations that J{sub i} is independent of sodium transport.

  14. Forest Canopy Processes in a Regional Chemical Transport Model

    NASA Astrophysics Data System (ADS)

    Makar, Paul; Staebler, Ralf; Akingunola, Ayodeji; Zhang, Junhua; McLinden, Chris; Kharol, Shailesh; Moran, Michael; Robichaud, Alain; Zhang, Leiming; Stroud, Craig; Pabla, Balbir; Cheung, Philip

    2016-04-01

    Forest canopies have typically been absent or highly parameterized in regional chemical transport models. Some forest-related processes are often considered - for example, biogenic emissions from the forests are included as a flux lower boundary condition on vertical diffusion, as is deposition to vegetation. However, real forest canopies comprise a much more complicated set of processes, at scales below the "transport model-resolved scale" of vertical levels usually employed in regional transport models. Advective and diffusive transport within the forest canopy typically scale with the height of the canopy, and the former process tends to dominate over the latter. Emissions of biogenic hydrocarbons arise from the foliage, which may be located tens of metres above the surface, while emissions of biogenic nitric oxide from decaying plant matter are located at the surface - in contrast to the surface flux boundary condition usually employed in chemical transport models. Deposition, similarly, is usually parameterized as a flux boundary condition, but may be differentiated between fluxes to vegetation and fluxes to the surface when the canopy scale is considered. The chemical environment also changes within forest canopies: shading, temperature, and relativity humidity changes with height within the canopy may influence chemical reaction rates. These processes have been observed in a host of measurement studies, and have been simulated using site-specific one-dimensional forest canopy models. Their influence on regional scale chemistry has been unknown, until now. In this work, we describe the results of the first attempt to include complex canopy processes within a regional chemical transport model (GEM-MACH). The original model core was subdivided into "canopy" and "non-canopy" subdomains. In the former, three additional near-surface layers based on spatially and seasonally varying satellite-derived canopy height and leaf area index were added to the original model

  15. Study of active cooling for supersonic transports

    NASA Technical Reports Server (NTRS)

    Brewer, G. D.; Morris, R. E.

    1975-01-01

    The potential benefits of using the fuel heat sink of hydrogen fueled supersonic transports for cooling large portions of the aircraft wing and fuselage are examined. The heat transfer would be accomplished by using an intermediate fluid such as an ethylene glycol-water solution. Some of the advantages of the system are: (1) reduced costs by using aluminum in place of titanium, (2) reduced cabin heat loads, and (3) more favorable environmental conditions for the aircraft systems. A liquid hydrogen fueled, Mach 2.7 supersonic transport aircraft design was used for the reference uncooled vehicle. The cooled aircraft designs were analyzed to determine their heat sink capability, the extent and location of feasible cooled surfaces, and the coolant passage size and spacing.

  16. Features, Events, and Processes in UZ Flow and Transport

    SciTech Connect

    J.E. Houseworth

    2001-04-10

    Unsaturated zone (UZ) flow and radionuclide transport is a component of the natural barriers that affects potential repository performance. The total system performance assessment (TSPA) model, and underlying process models, of this natural barrier component capture some, but not all, of the associated features, events, and processes (FEPs) as identified in the FEPs Database (Freeze, et al. 2001 [154365]). This analysis and model report (AMR) discusses all FEPs identified as associated with UZ flow and radionuclide transport. The purpose of this analysis is to give a comprehensive summary of all UZ flow and radionuclide transport FEPs and their treatment in, or exclusion from, TSPA models. The scope of this analysis is to provide a summary of the FEPs associated with the UZ flow and radionuclide transport and to provide a reference roadmap to other documentation where detailed discussions of these FEPs, treated explicitly in TSPA models, are offered. Other FEPs may be screened out from treatment in TSPA by direct regulatory exclusion or through arguments concerning low probability and/or low consequence of the FEPs on potential repository performance. Arguments for exclusion of FEPs are presented in this analysis. Exclusion of specific FEPs from the UZ flow and transport models does not necessarily imply that the FEP is excluded from the TSPA. Similarly, in the treatment of included FEPs, only the way in which the FEPs are included in the UZ flow and transport models is discussed in this document. This report has been prepared in accordance with the technical work plan for the unsaturated zone subproduct element (CRWMS M&O 2000 [153447]). The purpose of this report is to document that all FEPs are either included in UZ flow and transport models for TSPA, or can be excluded from UZ flow and transport models for TSPA on the basis of low probability or low consequence. Arguments for exclusion are presented in this analysis. Exclusion of specific FEPs from UZ flow and

  17. Processes of technology assessment: The National Transportation Safety Board

    NASA Technical Reports Server (NTRS)

    Weiss, E.

    1972-01-01

    The functions and operations of the Safety Board as related to technology assessment are described, and a brief history of the Safety Board is given. Recommendations made for safety in all areas of transportation and the actions taken are listed. Although accident investigation is an important aspect of NTSB's activity, it is felt that the greatest contribution is in pressing for development of better accident prevention programs. Efforts of the Safety Board in changing transportation technology to improve safety and prevent accidents are illustrated.

  18. 1995 national heat transfer conference: Proceedings. Volume 4: Transport phenomena in manufacturing and materials processing; Transport phenomena in materials joining processes; Transport phenomena in net shape manufacturing; HTD-Volume 306

    SciTech Connect

    Mahajan, R.L.

    1995-12-31

    This book is divided into three sections: (1) transport phenomena in manufacturing and materials processing; (2) transport phenomena in net shape manufacturing: and (3) transport phenomena in materials joining processes. Separate abstracts were prepared for most papers in this volume.

  19. Modeling of natural organic matter transport processes in groundwater.

    PubMed Central

    Yeh, T C; Mas-Pla, J; McCarthy, J F; Williams, T M

    1995-01-01

    A forced-gradient tracer test was conducted at the Georgetown site to study the transport of natural organic matter (NOM) in groundwater. In particular, the goal of this experiment was to investigate the interactions between NOM and the aquifer matrix. A detailed three-dimensional characterization of the hydrologic conductivity heterogeneity of the site was obtained using slug tests. The transport of a conservative tracer (chloride) was successfully reproduced using these conductivity data. Despite the good simulation of the flow field, NOM breakthrough curves could not be reproduced using a two-site sorption model with spatially constant parameters. Preliminary results suggest that different mechanisms for the adsorption/desorption processes, as well as their spatial variability, may significantly affect the transport and fate of NOM. PMID:7621798

  20. Modeling Multi-process Transport of Pathogens in Porous Media

    NASA Astrophysics Data System (ADS)

    Cheng, L.; Brusseau, M. L.

    2004-12-01

    The transport behavior of microorganisms in porous media is of interest with regard to the fate of pathogens associated with wastewater recharge, riverbank filtration, and land application of biosolids. This interest has fomented research on the transport of pathogens in the subsurface environment. The factors influencing pathogen transport within the subsurface environment include advection, dispersion, filtration, and inactivation. The filtration process, which mediates the magnitude and rate of pathogen retention, comprises several mechanisms such as attachment to porous-medium surfaces, straining, and sedimentation. We present a mathematical model wherein individual filtration mechanisms are explicitly incorporated along with advection, dispersion, and inactivation. The performance of the model is evaluated by applying it to several data sets obtained from miscible-displacement experiments conducted using various pathogens. Input parameters are obtained to the extent possible from independent means.

  1. An Abiotic Glass-Bead Collector Exhibiting Active Transport

    NASA Astrophysics Data System (ADS)

    Goto, Youhei; Kanda, Masato; Yamamoto, Daigo; Shioi, Akihisa

    2015-09-01

    Animals relocate objects as needed by active motion. Active transport is ubiquitous in living organisms but has been difficult to realize in abiotic systems. Here we show that a self-propelled droplet can gather scattered beads toward one place on a floor and sweep it clean. This is a biomimetic active transport with loadings and unloadings, because the transport was performed by a carrier and the motion of the carrier was maintained by the energy of the chemical reaction. The oil droplet produced fluctuation of the local number density of the beads on the floor, followed by its autocatalytic growth. This mechanism may inspire the technologies based on active transport wherein chemical and physical substances migrate as in living organisms.

  2. Is the wash-off process of road-deposited sediment source limited or transport limited?

    PubMed

    Zhao, Hongtao; Chen, Xuefei; Hao, Shaonan; Jiang, Yan; Zhao, Jiang; Zou, Changliang; Xie, Wenxia

    2016-09-01

    An in-depth understanding of the road-deposited sediments (RDS) wash-off process is essential to estimation of urban surface runoff pollution load and to designing methods to minimize the adverse impacts on the receiving waters. There are two debatable RDS wash-off views: source limited and transport limited. The RDS build-up and wash-off process was characterized to explore what determines the wash-off process to be source limited or transport limited based on twelve RDS sampling activities on an urban road in Beijing. The results showed that two natural rain events (2.0mm and 23.2mm) reduced the total RDS mass by 30%-40%, and that finer particles (<105μm) contributed 60%-80% of the wash-off load. Both single- and multi-rain events caused the RDS particle grain size to become coarser, while dry days made the RDS particle grain size finer. These findings indicated that the bulk RDS particles wash-off tends to be transport limited, but that finer particles tend to be source limited. To further explore and confirm the results of the field experiment, a total of 40 simulated rain events were designed to observe the RDS wash-off with different particle size fractions. The finer particles have a higher wash-off percentage (Fw) than the coarser particles, and the Fw values provide a good view to characterize the wash-off process. The key conclusions drawn from the combined field and simulated experiments data are: (i) Finer and coarser particle wash-off processes tend to be source limited and transport limited, respectively. (ii) The source and transport limited processes occur during the initial period (the first flush) and later periods, respectively. (iii) The smaller and larger rain events tend to be transport limited and source limited, respectively. Overall, the wash-off process is generally a combination of source and transport limited processes. PMID:27135567

  3. Scaling and predicting solute transport processes in riverine ecosystems

    NASA Astrophysics Data System (ADS)

    Gonzalez-Pinzon, R.; Haggerty, R.; Camacho Botero, L. A.

    2012-12-01

    In the last three decades, research on solute transport and nutrient processing has revealed complex interactions between landscapes and stream ecosystems, and numerous attempts to scale and predict these processes have been primarily limited by the difficulty of measuring and extrapolating hydrodynamic and geomorphic characteristics. We hypothesize that there should be predictable patterns in the way that streams interact with their landscapes, because those interactions are in the form of energy, mass and momentum, which are conservative and interrelated properties. Therefore, despite local hydrogeomorphic characteristics define the actual extent of solute transport processes in a given riverine ecosystem, the physical imprints marked-up in breakthrough curves (BTCs) should have scaling properties. To evaluate our hypothesis we created an extensive database that includes 133 BTCs from conservative tracer experiments conducted under different hydrologic conditions (1 lt/s to 1197 m3/s), different experimental conditions (10s of meters to 10s of kilometers), different geographic positions (South and North America, Europe, Australia, Antarctica), and different types of lotic environments, i.e., urban manmade channels, forested headwater streams, desert-like streams, hyporheic wells, and major rivers. We investigated the existence of patterns in conservative solute transport using a model-independent approach, i.e., temporal moments of the histories of tracer experiments. Our results show that the normalized first absolute moment is correlated with the second and third moments with R2>0.99 for all riverine ecosystems. Most importantly, the first central temporal moment of the distributions (mean travel time) is correlated with the second (variance) with an R2>0.93, and the correlation between the second central moment and the third central moment (skewness) takes the form of the coefficient of skewness (CSK) with an R2>0.98, defining a statistically averaged CSK= 1

  4. Nonlinear transport processes in tokamak plasmas. I. The collisional regimes

    SciTech Connect

    Sonnino, Giorgio; Peeters, Philippe

    2008-06-15

    An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear ('Onsager') transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch-Schlueter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for Joint European Torus (JET) plasmas are also reported. It is found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor that may be of the order 10{sup 2}. The nonlinear classical coefficients exceed the neoclassical ones by a factor that may be of order 2. For JET, the discrepancy between experimental and theoretical results for the electron losses is therefore significantly reduced by a factor 10{sup 2} when the nonlinear contributions are duly taken into account but, there is still a factor of 10{sup 2} to be explained. This is most likely due to turbulence. The expressions of the ion transport coefficients, determined by the neoclassical theory in these two regimes, remain unaltered. The low-collisional regimes, i.e., the plateau and the banana regimes, are analyzed in the second part of this work.

  5. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Public transportation programs and activities in existing facilities. 37.61 Section 37.61 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities...

  6. Active transportation safety features around schools in Canada.

    PubMed

    Pinkerton, Bryn; Rosu, Andrei; Janssen, Ian; Pickett, William

    2013-11-01

    The purpose of this study was to describe the presence and quality of active transportation safety features in Canadian school environments that relate to pedestrian and bicycle safety. Variations in these features and associated traffic concerns as perceived by school administrators were examined by geographic status and school type. The study was based on schools that participated in 2009/2010 Health Behaviour in School-aged Children (HBSC) survey. ArcGIS software version 10 and Google Earth were used to assess the presence and quality of ten different active transportation safety features. Findings suggest that there are crosswalks and good sidewalk coverage in the environments surrounding most Canadian schools, but a dearth of bicycle lanes and other traffic calming measures (e.g., speed bumps, traffic chokers). Significant urban/rural inequities exist with a greater prevalence of sidewalk coverage, crosswalks, traffic medians, and speed bumps in urban areas. With the exception of bicycle lanes, the active transportation safety features that were present were generally rated as high quality. Traffic was more of a concern to administrators in urban areas. This study provides novel information about active transportation safety features in Canadian school environments. This information could help guide public health efforts aimed at increasing active transportation levels while simultaneously decreasing active transportation injuries. PMID:24185844

  7. Entropic Ratchet transport of interacting active Brownian particles

    SciTech Connect

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

    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.

  8. Development of active-transport membrane devices

    SciTech Connect

    Laciak, D.V.

    1994-07-01

    This report introduces the concept of Air Products` AT membranes for the separation of NH{sub 3} and CO{sub 2} from process gas streams and presents results from the first year fabrication concept development studies.

  9. Contemporary sediment-transport processes in submarine canyons.

    PubMed

    Puig, Pere; Palanques, Albert; Martín, Jacobo

    2014-01-01

    Submarine canyons are morphological incisions into continental margins that act as major conduits of sediment from shallow- to deep-sea regions. However, the exact mechanisms involved in sediment transfer within submarine canyons are still a subject of investigation. Several studies have provided direct information about contemporary sedimentary processes in submarine canyons that suggests different modes of transport and various triggering mechanisms. Storm-induced turbidity currents and enhanced off-shelf advection, hyperpycnal flows and failures of recently deposited fluvial sediments, dense shelf-water cascading, canyon-flank failures, and trawling-induced resuspension largely dominate present-day sediment transfer through canyons. Additionally, internal waves periodically resuspend ephemeral deposits within canyons and contribute to dispersing particles or retaining and accumulating them in specific regions. These transport processes commonly deposit sediments in the upper- and middle-canyon reaches for decades or centuries before being completely or partially flushed farther down-canyon by large sediment failures. PMID:23937169

  10. Active matter transport on complex substrates

    NASA Astrophysics Data System (ADS)

    Olson Reichhardt, C. J.; Ray, D.; Reichhardt, C.

    2014-09-01

    Colloids interacting with complex landscapes created by optical means exhibit a remarkable variety of novel orderings and equilibrium states. It is also possible to study nonequilibrium properties for colloids driven over optical traps when there is an additional external electric field or some other form of external driving. Recently a new type of colloidal system has been realized in which the colloids are self-driven or self-motile and undergo a persistent random walk. Self motile particle systems fall into the broader class of self-driven systems called active matter. For the case of externally driven colloidal particles moving over random or periodic arrangements of traps, various types of pinning or jamming effects can arise. Far less is known about the mobility of active matter particles in the presence or random or periodic substrates. For example, it is not known whether increasing the activity of the particles would reduce the jamming effects caused by effective friction between particles. Here we show by varying the activity and the density of active particles that various types of motion can arise. In some cases, increasing the self-driving leads to a reduction in the net flow of particles through the system.

  11. Modeling sediment transport as a spatio-temporal Markov process.

    NASA Astrophysics Data System (ADS)

    Heyman, Joris; Ancey, Christophe

    2014-05-01

    Despite a century of research about sediment transport by bedload occuring in rivers, its constitutive laws remain largely unknown. The proof being that our ability to predict mid-to-long term transported volumes within reasonable confidence interval is almost null. The intrinsic fluctuating nature of bedload transport may be one of the most important reasons why classical approaches fail. Microscopic probabilistic framework has the advantage of taking into account these fluctuations at the particle scale, to understand their effect on the macroscopic variables such as sediment flux. In this framework, bedload transport is seen as the random motion of particles (sand, gravel, pebbles...) over a two-dimensional surface (the river bed). The number of particles in motion, as well as their velocities, are random variables. In this talk, we show how a simple birth-death Markov model governing particle motion on a regular lattice accurately reproduces the spatio-temporal correlations observed at the macroscopic level. Entrainment, deposition and transport of particles by the turbulent fluid (air or water) are supposed to be independent and memoryless processes that modify the number of particles in motion. By means of the Poisson representation, we obtained a Fokker-Planck equation that is exactly equivalent to the master equation and thus valid for all cell sizes. The analysis shows that the number of moving particles evolves locally far from thermodynamic equilibrium. Several analytical results are presented and compared to experimental data. The index of dispersion (or variance over mean ratio) is proved to grow from unity at small scales to larger values at larger scales confirming the non Poisonnian behavior of bedload transport. Also, we study the one and two dimensional K-function, which gives the average number of moving particles located in a ball centered at a particle centroid function of the ball's radius.

  12. Classroom Activities in Transportation: Technology Education.

    ERIC Educational Resources Information Center

    Wisconsin State Dept. of Public Instruction, Madison.

    This curriculum supplement was designed to correlate directly with "A Guide to Curriculum Planning in Technology Education," published by the Wisconsin Department of Public Instruction. It is also a companion book to three other classroom activity compilations, one in each of the other three major systems of technology--manufacturing,…

  13. Activation of a new proline transport system in Salmonella typhimurium.

    PubMed

    Ekena, K; Liao, M K; Maloy, S

    1990-06-01

    Proline uptake can be mediated by three different transport systems in wild-type Salmonella typhimurium: a high-affinity proline transport system encoded by the putP gene and two glycine-betaine transport systems with a low affinity for proline encoded by the proP and proU genes. However, only the PutP permease transports proline well enough t allow growth on proline as a sole carbon or nitrogen source. By selecting for mutations that allow a putP mutant to grow on proline as a sole nitrogen source, we isolated mutants (designated proZ) that appeared to activate a cryptic proline transport system. These mutants enhanced the transport of proline and proline analogs but did not require the function of any of the known proline transport genes. The mutations mapped between 75 and 77.5 min on the S. typhimurium linkage map. Proline transport by the proZ mutants was competitively inhibited by isoleucine and leucine, which suggests that the ProZ phenotype may be due to unusual mutations that alter the substrate specificity of the branched-chain amino acid transport system encoded by the liv genes. PMID:2160931

  14. Analytical model of reactive transport processes with spatially variable coefficients.

    PubMed

    Simpson, Matthew J; Morrow, Liam C

    2015-05-01

    Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems. PMID:26064648

  15. Analytical model of reactive transport processes with spatially variable coefficients

    PubMed Central

    Simpson, Matthew J.; Morrow, Liam C.

    2015-01-01

    Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems. PMID:26064648

  16. UV Irradiation Accelerates Amyloid Precursor Protein (APP) Processing and Disrupts APP Axonal Transport

    PubMed Central

    Almenar-Queralt, Angels; Falzone, Tomas L.; Shen, Zhouxin; Lillo, Concepcion; Killian, Rhiannon L.; Arreola, Angela S.; Niederst, Emily D.; Ng, Kheng S.; Kim, Sonia N.; Briggs, Steven P.; Williams, David S.

    2014-01-01

    Overexpression and/or abnormal cleavage of amyloid precursor protein (APP) are linked to Alzheimer's disease (AD) development and progression. However, the molecular mechanisms regulating cellular levels of APP or its processing, and the physiological and pathological consequences of altered processing are not well understood. Here, using mouse and human cells, we found that neuronal damage induced by UV irradiation leads to specific APP, APLP1, and APLP2 decline by accelerating their secretase-dependent processing. Pharmacological inhibition of endosomal/lysosomal activity partially protects UV-induced APP processing implying contribution of the endosomal and/or lysosomal compartments in this process. We found that a biological consequence of UV-induced γ-secretase processing of APP is impairment of APP axonal transport. To probe the functional consequences of impaired APP axonal transport, we isolated and analyzed presumptive APP-containing axonal transport vesicles from mouse cortical synaptosomes using electron microscopy, biochemical, and mass spectrometry analyses. We identified a population of morphologically heterogeneous organelles that contains APP, the secretase machinery, molecular motors, and previously proposed and new residents of APP vesicles. These possible cargoes are enriched in proteins whose dysfunction could contribute to neuronal malfunction and diseases of the nervous system including AD. Together, these results suggest that damage-induced APP processing might impair APP axonal transport, which could result in failure of synaptic maintenance and neuronal dysfunction. PMID:24573290

  17. The Role of Flexible Loops in Folding, Trafficking and Activity of Equilibrative Nucleoside Transporters

    PubMed Central

    Aseervatham, Jaya; Tran, Lucky; Machaca, Khaled; Boudker, Olga

    2015-01-01

    Equilibrative nucleoside transporters (ENTs) are integral membrane proteins, which reside in plasma membranes of all eukaryotic cells and mediate thermodynamically downhill transport of nucleosides. This process is essential for nucleoside recycling, and also plays a key role in terminating adenosine-mediated cellular signaling. Furthermore, ENTs mediate the uptake of many drugs, including anticancer and antiviral nucleoside analogues. The structure and mechanism, by which ENTs catalyze trans-membrane transport of their substrates, remain unknown. To identify the core of the transporter needed for stability, activity, and for its correct trafficking to the plasma membrane, we have expressed human ENT deletion mutants in Xenopus laevis oocytes and determined their localization, transport properties and susceptibility to inhibition. We found that the carboxyl terminal trans-membrane segments are essential for correct protein folding and trafficking. In contrast, the soluble extracellular and intracellular loops appear to be dispensable, and must be involved in the fine-tuning of transport regulation. PMID:26406980

  18. The Role of Flexible Loops in Folding, Trafficking and Activity of Equilibrative Nucleoside Transporters.

    PubMed

    Aseervatham, Jaya; Tran, Lucky; Machaca, Khaled; Boudker, Olga

    2015-01-01

    Equilibrative nucleoside transporters (ENTs) are integral membrane proteins, which reside in plasma membranes of all eukaryotic cells and mediate thermodynamically downhill transport of nucleosides. This process is essential for nucleoside recycling, and also plays a key role in terminating adenosine-mediated cellular signaling. Furthermore, ENTs mediate the uptake of many drugs, including anticancer and antiviral nucleoside analogues. The structure and mechanism, by which ENTs catalyze trans-membrane transport of their substrates, remain unknown. To identify the core of the transporter needed for stability, activity, and for its correct trafficking to the plasma membrane, we have expressed human ENT deletion mutants in Xenopus laevis oocytes and determined their localization, transport properties and susceptibility to inhibition. We found that the carboxyl terminal trans-membrane segments are essential for correct protein folding and trafficking. In contrast, the soluble extracellular and intracellular loops appear to be dispensable, and must be involved in the fine-tuning of transport regulation. PMID:26406980

  19. Active Transportation to School: Findings from a National Survey

    ERIC Educational Resources Information Center

    Fulton, Janet E.; Shisler, Jessica L.; Yore, Michelle M.; Caspersen, Carl J.

    2005-01-01

    In the past, active transportation to school offered an important source of daily physical activity for youth; more recently, however, factors related to distance, safety, or physical or social environments may have contributed to the proportion of children who travel to school by motorized vehicle. The authors examine the characteristics of…

  20. Monitoring of sediment transport processes using tracer stones

    NASA Astrophysics Data System (ADS)

    Redtenbacher, Matthias; Harb, Gabriele; Barbas, Teresa; Schneider, Josef

    2014-05-01

    In the last decades the vulnerability of our civilization to geomorphological damaging events like debris flows and exceptional floods increased. The reasons are, on one side, that the global hydrological cycle became more intense during the recent past and on the other side that the material assets of the population increased. Risk prevention, risk analysis and forecast methods thus became more important. Geomorphological processes are often not easy to analyse. To get information about the probability and the consequences of these increasing events, it is necessary to analyse the availability of sediments in the catchment area, the erosion processes of the sediment and the transport of the sediments along torrents. The project ClimCatch, which started in April 2012, investigates the torrential sediment transport processes in a non-glaciated Alpine valley in Austria and the related natural hazards under the viewpoint of the on-going climate change. Due to an extreme precipitation event in 2011 debris flow-similar discharges occurred in this catchment and since that the sediment sources are highly erodible there. The aims of the project are to derive a quantitative sediment budget model, including geomorphic process domains, determining sediment transport in the river system and the measurement of bed load output, besides others. To quantify river sediment dynamics several different methodologies are applied within the project. Discharge and sediment transport measurement as well as hydrological stations are installed in the catchment area. Aggradation and erosion are analysed by means of laser scanning technology in the sediment storage basin which is located at the outlet of the catchment. The observation and measurement of the sediment transport is performed by the application of radio telemetry stones and colour tracer stones. Line pebble counting, automated grain size determination using photographs and sieving on-site is performed to get qualitative sediment

  1. Microchamber Device for Detection of Transporter Activity of Adherent Cells

    PubMed Central

    Tsugane, Mamiko; Uejima, Etsuko; Suzuki, Hiroaki

    2015-01-01

    We present a method to detect the transporter activity of intact adherent cells using a microchamber device. When adherent cells are seeded onto the poly-di-methyl siloxane substrate having microchambers with openings smaller than the size of a cell, the cells form a confluent layer that covers the microchambers, creating minute, confined spaces. As substances exported across the cell membrane accumulate, transporter activity can be detected by observing the fluorescence intensity increase in the microchamber. We tested the microchamber device with HeLa cells over-expressing MDR1, an ATP-binding cassette transporter, and succeeded in detecting the transport of fluorescence-conjugated paclitaxel, the anti-cancer drug, at the single-cell level. PMID:25853126

  2. Condensation and transport in the totally asymmetric inclusion process (TASIP)

    NASA Astrophysics Data System (ADS)

    Knebel, Johannes; Weber, Markus F.; Krueger, Torben; Frey, Erwin

    Transport phenomena are often modeled by the hopping of particles on regular lattices or networks. Such models describe, e.g., the exclusive movement of molecular motors along microtubules: no two motors may occupy the same site. In our work, we study inclusion processes that are the bosonic analogues of the fermionic exclusion processes. In inclusion processes, many particles may occupy a single site and hopping rates depend linearly on the occupation of departure and arrival sites. Particles thus attract other particles to their own site. Condensation occurs when particles collectively cluster in one or multiple sites, whereas other sites become depleted.We showed that inclusion processes describe both the selection of strategies in evolutionary zero-sum games and the condensation of non-interacting bosons into multiple quantum states in driven-dissipative systems. The condensation is captured by the antisymmetric Lotka-Volterra equation (ALVE), which constitutes a nonlinearly coupled dynamical system. We derived an algebraic method to analyze the ALVE and to determine the condensates. Our approach allows for the design of networks that result in condensates with oscillating occupations, and yields insight into the interplay between network topology and transport properties. Deutsche Forschungsgemeinschaft (SFB-TR12), German Excellence Initiative (Nanosystems Initiative Munich), Center for NanoScience Munich.

  3. Hyporheic flow and transport processes: mechanisms, models, and biogeochemical implications

    USGS Publications Warehouse

    Boano, Fulvio; Harvey, Judson W.; Marion, Andrea; Packman, Aaron I.; Revelli, Roberto; Ridolfi, Luca; Anders, Wörman

    2014-01-01

    Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed."

  4. Hyporheic flow and transport processes: Mechanisms, models, and biogeochemical implications

    NASA Astrophysics Data System (ADS)

    Boano, F.; Harvey, J. W.; Marion, A.; Packman, A. I.; Revelli, R.; Ridolfi, L.; Wörman, A.

    2014-12-01

    Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed.

  5. Characterization of Transport and Solidification in the Metal Recycling Processes

    SciTech Connect

    M. A. Ebadian; R. C. Xin; Z. F. Dong

    1997-08-06

    The characterization of the transport and solidification of metal in the melting and casting processes is significant for the optimization of the radioactively contaminated metal recycling and refining processes. . In this research project, the transport process in the melting and solidification of metal was numerically predicted, and the microstructure and radionuclide distribution have been characterized by scanning electron microscope/electron diffractive X-ray (SEWEDX) analysis using cesium chloride (CSC1) as the radionuclide surrogate. In the melting and solidification process, a resistance furnace whose heating and cooling rates are program- controlled in the helium atmosphere was used. The characterization procedures included weighing, melting and solidification, weighing after solidification, sample preparation, and SEM/EDX analysis. This analytical methodology can be used to characterize metal recycling and refining products in order to evaluate the performance of the recycling process. The data obtained provide much valuable information that is necessary for the enhancement of radioactive contaminated metal decontamination and recycling technologies. The numerical method for the prediction of the melting and solidification process can be implemented in the control and monitoring system-of the melting and casting process in radioactive contaminated metal recycling. The use of radionuclide surrogates instead of real radionuclides enables the research to be performed without causing harmfid effects on people or the community. This characterization process has been conducted at the Hemispheric Center for Environmental Technology (HCET) at Florida International University since October 1995. Tests have been conducted on aluminum (Al) and copper (Cu) using cesium chloride (CSCI) as a radionuclide surrogate, and information regarding the radionuclide transfer and distribution in melting and solidification process has been obtained. The numerical simulation of

  6. Collecting Duct Principal Cell Transport Processes and Their Regulation

    PubMed Central

    Soundararajan, Rama; Trimpert, Christiane; Kashlan, Ossama B.; Deen, Peter M.T.; Kohan, Donald E.

    2015-01-01

    The principal cell of the kidney collecting duct is one of the most highly regulated epithelial cell types in vertebrates. The effects of hormonal, autocrine, and paracrine factors to regulate principal cell transport processes are central to the maintenance of fluid and electrolyte balance in the face of wide variations in food and water intake. In marked contrast with the epithelial cells lining the proximal tubule, the collecting duct is electrically tight, and ion and osmotic gradients can be very high. The central role of principal cells in salt and water transport is reflected by their defining transporters—the epithelial Na+ channel (ENaC), the renal outer medullary K+ channel, and the aquaporin 2 (AQP2) water channel. The coordinated regulation of ENaC by aldosterone, and AQP2 by arginine vasopressin (AVP) in principal cells is essential for the control of plasma Na+ and K+ concentrations, extracellular fluid volume, and BP. In addition to these essential hormones, additional neuronal, physical, and chemical factors influence Na+, K+, and water homeostasis. Notably, a variety of secreted paracrine and autocrine agents such as bradykinin, ATP, endothelin, nitric oxide, and prostaglandin E2 counterbalance and limit the natriferic effects of aldosterone and the water-retaining effects of AVP. Considerable recent progress has improved our understanding of the transporters, receptors, second messengers, and signaling events that mediate principal cell responses to changing environments in health and disease. This review primarily addresses the structure and function of the key transporters and the complex interplay of regulatory factors that modulate principal cell ion and water transport. PMID:24875192

  7. CONVERTING PYROLYSIS OILS TO RENEWABLE TRANSPORT FUELS: PROCESSING CHALLENGES & OPPORTUNITIES

    SciTech Connect

    Holmgren, Jennifer; Nair, Prabhakar N.; Elliott, Douglas C.; Bain, Richard; Marinangelli, Richard

    2008-03-11

    To enable a sustained supply of biomass-based transportation fuels, the capability to process feedstocks outside the food chain must be developed. Significant industry efforts are underway to develop these new technologies, such as converting cellulosic wastes to ethanol. UOP, in partnership with U.S. Government labs, NREL and PNNL, is developing an alternate route using cellulosic feedstocks. The waste biomass is first subjected to a fast pyrolysis operation to generate pyrolysis oil (pyoil for short). Current efforts are focused on developing a thermochemical platform to convert pyoils to renewable gasoline, diesel and jet fuel. The fuels produced will be indistinguishable from their fossil fuel counterparts and, therefore, will be compatible with existing transport and distribution infrastructure.

  8. Chapman Conference on Sediment Transport Processes in Estuaries

    NASA Astrophysics Data System (ADS)

    Perillo, Gerardo M. E.; Lavelle, J. William

    During the week of June 13-17, 1988, 72 sediment transport researchers “aggregated” at the Universidad Nacional del Sur in Bahfa Blanca, Argentina, to participate in an AGU Chapman Conference on Sediment Transport Processes in Estuaries. The main goals of the meeting were to discuss recent advances in estuarine science, to appraise promising future research directions, and to develop contacts and establish working relationships between Latin American and non-Latin- American estuarine researchers. The meeting drew participants from Argentina, Brazil, Chile, Uruguay, Venezuela, the U.S., Canada, Britain, France, the Federal Republic of Germany, The Netherlands, and South Africa. Meeting cosponsors were UNESCO, Secretaria de Ciencía y Técnica, Consejo Nacional de Investigaciones Cientificas y Técnicas, Comision de Investigaciones Cientificas de la Provincia de Buenos Aires, Universidad del Sur, Municipalidad de Bahia Blanca, Asociaciôn Argentina de Geofisicos y Geodestas (AGU sister organization), and the Instituto Argentino de Oceanografia (IADO).

  9. Convection in the Physical Vapor Transport Process-I: Thermal

    NASA Technical Reports Server (NTRS)

    Duval, Walter M. B.

    1994-01-01

    The effects of convection on diffusive-convective physical vapor transport process are examined computationally. We analyze conditions ranging from typical laboratory conditions to conditions achievable only in a low gravity environment. This corresponds to thermal Rayleigh numbers Ra, ranging from 1.80 x 10 to 1.92 x 10(exp 6). Our results indicate that the effect of the sublimation and condensation fluxes at the boundaries is to increase the threshold of instability. For typical ground based conditions, time dependent oscillatory convection can occur. This results in unsteady transport, and non- uniform temperature and concentration gradients at the crystal interface. Spectral analysis of the flow field shows parametric regions exhibiting both an oscillatory approach to steady state and a chaotic transient to a periodic state. Low gravity conditions stabilize the flow field. Convective effects are effectively reduced, thus resulting in uniform temperature and concentration gradients at the interface, a desirable condition for crystal growth.

  10. Convection in the Physical Vapor Transport Process. 1; Thermal

    NASA Technical Reports Server (NTRS)

    Duval, Walter M. B.

    1994-01-01

    The effects of convection on diffusive-convective physical vapor transport process are examined computationally. We analyze conditions ranging from typical laboratory conditions to conditions achievable only in a low gravity environment. This corresponds to thermal Rayleigh numbers Ra(sub tau) ranging from 1.80 x 10 to 1.92 x 10(exp 6). Our results indicate that the effect of the sublimation and condensation fluxes at the boundaries is to increase the threshold of instability. For typical ground based conditions, time dependent oscillatory convection can occur. This results in unsteady transport, and non-uniform temperature and concentration gradients at the crystal interface. Spectral analysis of the flow field shows parametric regions exhibiting both an oscillatory approach to steady state and a chaotic transient to a periodic state. Low gravity conditions stabilize the flow field. Convective effects are effectively reduced, thus resulting in uniform temperature and concentration gradients at the interface, a desirable condition for crystal growth.

  11. Cycles, randomness, and transport from chaotic dynamics to stochastic processes

    NASA Astrophysics Data System (ADS)

    Gaspard, Pierre

    2015-09-01

    An overview of advances at the frontier between dynamical systems theory and nonequilibrium statistical mechanics is given. Sensitivity to initial conditions is a mechanism at the origin of dynamical randomness—alias temporal disorder—in deterministic dynamical systems. In spatially extended systems, sustaining transport processes, such as diffusion, relationships can be established between the characteristic quantities of dynamical chaos and the transport coefficients, bringing new insight into the second law of thermodynamics. With methods from dynamical systems theory, the microscopic time-reversal symmetry can be shown to be broken at the statistical level of description in nonequilibrium systems. In this way, the thermodynamic entropy production turns out to be related to temporal disorder and its time asymmetry away from equilibrium.

  12. Cycles, randomness, and transport from chaotic dynamics to stochastic processes.

    PubMed

    Gaspard, Pierre

    2015-09-01

    An overview of advances at the frontier between dynamical systems theory and nonequilibrium statistical mechanics is given. Sensitivity to initial conditions is a mechanism at the origin of dynamical randomness-alias temporal disorder-in deterministic dynamical systems. In spatially extended systems, sustaining transport processes, such as diffusion, relationships can be established between the characteristic quantities of dynamical chaos and the transport coefficients, bringing new insight into the second law of thermodynamics. With methods from dynamical systems theory, the microscopic time-reversal symmetry can be shown to be broken at the statistical level of description in nonequilibrium systems. In this way, the thermodynamic entropy production turns out to be related to temporal disorder and its time asymmetry away from equilibrium. PMID:26428559

  13. Moisture processes accompanying convective activity

    NASA Technical Reports Server (NTRS)

    Sienkiewicz, M. E.; Scoggins, J. R.

    1982-01-01

    A moisture budget analysis was performed on data collected during the AVE 7 (May 2 to 3, 1978) and AVE-SESAME1 (April 10 to 11, 1979) experiments. Local rates-of-change of moisture were compared with average moisture divergence in the same time period. Results were presented as contoured plots in the horizontal and as vertical cross sections. These results were used to develop models of the distribution of moisture processes in the vicinity of convective areas in two layers representing lower and middle tropospheric conditions. Good correspondence was found between the residual term of the moisture budget and actual precipitation.

  14. Substrate regulation of ascorbate transport activity in astrocytes

    SciTech Connect

    Wilson, J.X.; Jaworski, E.M.; Kulaga, A.; Dixon, S.J. )

    1990-10-01

    Astrocytes possess a concentrative L-ascorbate (vitamin C) uptake mechanism involving a Na(+)-dependent L-ascorbate transporter located in the plasma membrane. The present experiments examined the effects of deprivation and supplementation of extracellular L-ascorbate on the activity of this transport system. Initial rates of L-ascorbate uptake were measured by incubating primary cultures of rat astrocytes with L-(14C)ascorbate for 1 min at 37 degrees C. We observed that the apparent maximal rate of uptake (Vmax) increased rapidly (less than 1 h) when cultured cells were deprived of L-ascorbate. In contrast, there was no change in the apparent affinity of the transport system for L-(14C)ascorbate. The increase in Vmax was reversed by addition of L-ascorbate, but not D-isoascorbate, to the medium. The effects of external ascorbate on ascorbate transport activity were specific in that preincubation of cultures with L-ascorbate did not affect uptake of 2-deoxy-D-(3H(G))glucose. We conclude that the astroglial ascorbate transport system is modulated by changes in substrate availability. Regulation of transport activity may play a role in intracellular ascorbate homeostasis by compensating for regional differences and temporal fluctuations in external ascorbate levels.

  15. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    SciTech Connect

    E.L. Hardin

    2000-07-17

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

  16. Memoryless self-reinforcing directionality in endosomal active transport within living cells

    NASA Astrophysics Data System (ADS)

    Chen, Kejia; Wang, Bo; Granick, Steve

    2015-06-01

    In contrast to Brownian transport, the active motility of microbes, cells, animals and even humans often follows another random process known as truncated Lévy walk. These stochastic motions are characterized by clustered small steps and intermittent longer jumps that often extend towards the size of the entire system. As there are repeated suggestions, although disagreement, that Lévy walks have functional advantages over Brownian motion in random searching and transport kinetics, their intentional engineering into active materials could be useful. Here, we show experimentally in the classic active matter system of intracellular trafficking that Brownian-like steps self-organize into truncated Lévy walks through an apparent time-independent positive feedback such that directional persistence increases with the distance travelled persistently. A molecular model that allows the maximum output of the active propelling forces to fluctuate slowly fits the experiments quantitatively. Our findings offer design principles for programming efficient transport in active materials.

  17. Transport equations of electrodiffusion processes in the laboratory reference frame.

    PubMed

    Garrido, Javier

    2006-02-23

    The transport equations of electrodiffusion processes use three reference frames for defining the fluxes: Fick's reference in diffusion, solvent-fixed reference in transference numbers, and laboratory fluxes in electric conductivity. The convenience of using only one reference frame is analyzed here from the point of view of the thermodynamics of irreversible processes. A relation between the fluxes of ions and solvent and the electric current density is deduced first from a mass and volume balance. This is then used to show that (i) the laboratory and Fick's diffusion coefficients are identical and (ii) the transference numbers of both the solvent and the ion in the laboratory reference frame are related. Finally, four experimental methods for the measurement of ion transference numbers are analyzed critically. New expressions for evaluating transference numbers for the moving boundary method and the chronopotentiometry technique are deduced. It is concluded that the ion transport equation in the laboratory reference frame plays a key role in the description of electrodiffusion processes. PMID:16494340

  18. Advanced Reactors Thermal Energy Transport for Process Industries

    SciTech Connect

    P. Sabharwall; S.J. Yoon; M.G. McKellar; C. Stoots; George Griffith

    2014-07-01

    The operation temperature of advanced nuclear reactors is generally higher than commercial light water reactors and thermal energy from advanced nuclear reactor can be used for various purposes such as liquid fuel production, district heating, desalination, hydrogen production, and other process heat applications, etc. Some of the major technology challenges that must be overcome before the advanced reactors could be licensed on the reactor side are qualification of next generation of nuclear fuel, materials that can withstand higher temperature, improvement in power cycle thermal efficiency by going to combined cycles, SCO2 cycles, successful demonstration of advanced compact heat exchangers in the prototypical conditions, and from the process side application the challenge is to transport the thermal energy from the reactor to the process plant with maximum efficiency (i.e., with minimum temperature drop). The main focus of this study is on doing a parametric study of efficient heat transport system, with different coolants (mainly, water, He, and molten salts) to determine maximum possible distance that can be achieved.

  19. Active water transport in unicellular algae: where, why, and how.

    PubMed

    Raven, John A; Doblin, Martina A

    2014-12-01

    The occurrence of active water transport (net transport against a free energy gradient) in photosynthetic organisms has been debated for several decades. Here, active water transport is considered in terms of its roles, where it is found, and the mechanisms by which it could occur. First there is a brief consideration of the possibility of active water transport into plant xylem in the generation of root pressure and the refilling of embolized xylem elements, and from an unsaturated atmosphere into terrestrial organisms living in habitats with limited availability of liquid water. There is then a more detailed consideration of volume and osmotic regulation in wall-less freshwater unicells, and the possibility of generation of buoyancy in marine phytoplankton such as large-celled diatoms. Calculations show that active water transport is a plausible mechanism to assist cells in upwards vertical movements, requires less energy than synthesis of low-density organic solutes, and potentially on a par with excluding certain ions from the vacuole. PMID:25205578

  20. Representing Microbial Processes in Environmental Reactive Transport Models

    NASA Astrophysics Data System (ADS)

    van Cappellen, P.

    2009-04-01

    Microorganisms play a key role in the biogeochemical functioning of the earth's surface and shallow subsurface. In the context of reactive transport modeling, a major challenge is to derive, parameterize, calibrate and verify mathematical expressions for microbially-mediated reactions in the environmental. This is best achieved by combining field observations, laboratory experiments, theoretical principles and modeling. Here, I will illustrate such an integrated approach for the case of microbial respiration processes in aquatic sediments. Important issues that will be covered include experimental design, model consistency and performance, as well as the bioenergetics and transient behavior of geomicrobial reaction systems.

  1. Identifying Clusters of Active Transportation Using Spatial Scan Statistics

    PubMed Central

    Huang, Lan; Stinchcomb, David G.; Pickle, Linda W.; Dill, Jennifer; Berrigan, David

    2009-01-01

    Background There is an intense interest in the possibility that neighborhood characteristics influence active transportation such as walking or biking. The purpose of this paper is to illustrate how a spatial cluster identification method can evaluate the geographic variation of active transportation and identify neighborhoods with unusually high/low levels of active transportation. Methods Self-reported walking/biking prevalence, demographic characteristics, street connectivity variables, and neighborhood socioeconomic data were collected from respondents to the 2001 California Health Interview Survey (CHIS; N=10,688) in Los Angeles County (LAC) and San Diego County (SDC). Spatial scan statistics were used to identify clusters of high or low prevalence (with and without age-adjustment) and the quantity of time spent walking and biking. The data, a subset from the 2001 CHIS, were analyzed in 2007–2008. Results Geographic clusters of significantly high or low prevalence of walking and biking were detected in LAC and SDC. Structural variables such as street connectivity and shorter block lengths are consistently associated with higher levels of active transportation, but associations between active transportation and socioeconomic variables at the individual and neighborhood levels are mixed. Only one cluster with less time spent walking and biking among walkers/bikers was detected in LAC, and this was of borderline significance. Age-adjustment affects the clustering pattern of walking/biking prevalence in LAC, but not in SDC. Conclusions The use of spatial scan statistics to identify significant clustering of health behaviors such as active transportation adds to the more traditional regression analysis that examines associations between behavior and environmental factors by identifying specific geographic areas with unusual levels of the behavior independent of predefined administrative units. PMID:19589451

  2. Interacting Physical and Biological Processes Affecting Nutrient Transport Through Human Dominated Landscapes

    NASA Astrophysics Data System (ADS)

    Finlay, J. C.

    2015-12-01

    Human activities increasingly dominate biogeochemical cycles of limiting nutrients on Earth. Urban and agricultural landscapes represent the largest sources of excess nutrients that drive water quality degradation. The physical structure of both urban and agricultural watersheds has been extensively modified, and these changes have large impacts on water and nutrient transport. Despite strong physical controls over nutrient transport in human dominated landscapes, biological processes play important roles in determining the fates of both nitrogen and phosphorus. This talk uses examples from research in urban and agricultural watersheds in the Midwestern USA to illustrate interactions of physical and biological controls over nutrient cycles that have shifted nitrogen (N) and phosphorus (P) sources and cycling in unexpected ways in response to management changes. In urban watersheds, efforts to improve water quality have been hindered by legacy sources of phosphorus added to storm water through transport to drainage systems by vegetation. Similarly, reductions in field erosion in agricultural watersheds have not led to major reductions in phosphorus transport, because of continued release of biological sources of P. Where management of phosphorus has been most effective in reducing eutrophication of lakes, decreases in N removal processes have led to long term increases in N concentration and transport. Together, these examples show important roles for biological processes affecting nutrient movement in highly modified landscapes. Consideration of the downstream physical and biological responses of management changes are thus critical toward identification of actions that will most effectively reduce excess nutrients watersheds and coastal zones.

  3. APP anterograde transport requires Rab3A GTPase activity for assembly of the transport vesicle

    PubMed Central

    Szodorai, A; Kuan, Y-H; Hunzelmann, S; Engel, U; Sakane, A; Sasaki, T; Takai, Y; Kirsch, J; Müller, U; Beyreuther, K; Brady, S; Morfini, G; Kins, S

    2010-01-01

    The amyloid precursor protein (APP) may be sequentially cleaved by β- and γ-secretases leading to accumulation of Aβ peptides in brains of Alzheimer’s Disease patients. Cleavage by α-secretase prevents Aβ generation. APP is anterogradely transported by conventional kinesin in a distinct transport vesicle, but both the biochemical composition of such a vesicle as well as the specific kinesin-1 motor responsible for transport are poorly defined. Here, we demonstrate by time-lapse analysis and immunoisolations that APP is a cargo of a vesicle containing the kinesin heavy chain isoform kinesin-1C, the small GTPase Rab3A and a specific subset of presynaptic protein components. Moreover, we report that assembly of kinesin-1C and APP in this vesicle type requires Rab3A GTPase activity. Finally, we show cleavage of APP in the analyzed transport vesicles by α-secretase activity, likely mediated by ADAM10. Together, these data indicate for the first time that maturation of transport vesicles, including coupling of conventional kinesin, requires Rab GTPase activity. PMID:19923287

  4. Virtual laboratory for the study of transport processes in surface waterflows

    NASA Astrophysics Data System (ADS)

    Aguilar, C.; Egüen, M.; Contreras, E.; Polo, M. J.

    2012-04-01

    The equations involved in the study of transport processes depend on the spatial and temporal scale of the study and according to the required level of detail can become very difficult to solve analytically. Besides, experimentation of processes with any transport phenomena involved is complex due to their natural or forced occurrence in the environment (eg. Rainfall-runoff, sediment yield, controlled and uncontrolled pollutant loadings, etc.) and the great diversity of substances and components with an specific chemical behavior. However, due to the numerous fields of application of transport phenomena (basic and applied research, hydrology and associated fluxes, sediment transport, pollutant loadings to water flows, industrial processes, soil and water quality, atmospheric emissions, legislation, etc.), realistic studies of transport processes are required. In this context, case study application, an active methodology according to the structural implications of the European Higher Education Area (EHEA), with the aid of computer tools constitute an interactive, instantaneous and flexible method with a new interplay between students and lecturers. Case studies allow the lecturer to design significant activities that generate knowledge in the students and motivates them to look for information, discuss, and be autonomous. This work presents the development of a graphical interface for the solution of different case studies for the acquisition of capacities and abilities in the autonomous apprenticeship of courses related to transport processes in Environmental Hydraulics. The interactive tool helps to develop and improve abilities in mixing and transport in surface water related courses. Thus, students clarify theoretical concepts and visualize processes with negative effects for the environment and that therefore, can only be reproduced in the laboratory or in the field under very controlled conditions and commonly with tracers instead of the real substances. The

  5. Isotopic constraints on atmospheric moisture transport processes in South America

    NASA Astrophysics Data System (ADS)

    Samuels-Crow, Kimberly E.

    The water cycle in the tropics and subtropics exerts a strong influence on Earth's climate. Isotopic ratios in modern water vapor can provide us with insights into low-latitude moisture-transport processes in the modern climate system, recorded in paleoclimate proxy records, and in general circulation models that we rely on to understand how our climate is changing. Advances in satellite and groundbased instruments in the past decade have improved measurements of isotopes in water vapor. In this study, I focus on satellite (chapters 2 and 3) and ground-based (chapters 2 and 4) measurements of isotopes in atmospheric water vapor to evaluate processes responsible for moisture transport in tropical and subtropical South America. Satellite-measured hydrogen isotope ratios (deltaD), mixing ratios (q), and outgoing longwave radiation (OLR) show that upwind convective intensity controls the seasonal variability in isotopic ratios in tropical Andean water vapor and leads to lower isotopic ratios than predicted by equilibrium isotope fractionation models (i.e. DdeltaD = deltaDmeasured - deltaD Rayleigh < 0 ‰) (chapter 2). Deep convection in the South American Summer Monsoon domain in austral summer and in the Inter-tropical Convergence Zone in austral winter leads to zones where DdeltaD is negative from the Lifted Condensation Level through the mid- to upper-troposphere and possibly above the Level of Neutral Buoyancy (chapter 3). In subtropical South America, nearly continuous measurements of isotopic ratios, mixing ratios, and deuterium-excess (i.e. d-excess = deltaD - (8*delta 18O)) indicate that condensation under ice supersaturated conditions and mixing with moister air play important roles in controlling moisture transport to the hyperarid Chajnantor Plateau.

  6. Features, Events and Processes in UZ Flow and Transport

    SciTech Connect

    P. Persoff

    2005-08-04

    The purpose of this report is to evaluate and document the inclusion or exclusion of the unsaturated zone (UZ) features, events, and processes (FEPs) with respect to modeling that supports the total system performance assessment (TSPA) for license application (LA) for a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either Included or Excluded, is given for each FEP, along with the technical basis for the screening decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) in 10 CFR 63.114 (d, e, and f) [DIRS 173273]. The FEPs deal with UZ flow and radionuclide transport, including climate, surface water infiltration, percolation, drift seepage, and thermally coupled processes. This analysis summarizes the implementation of each FEP in TSPA-LA (that is, how the FEP is included) and also provides the technical basis for exclusion from TSPA-LA (that is, why the FEP is excluded). This report supports TSPA-LA.

  7. Features, Events, and Processes in UZ and Transport

    SciTech Connect

    P. Persoff

    2004-11-06

    The purpose of this report is to evaluate and document the inclusion or exclusion of the unsaturated zone (UZ) features, events, and processes (FEPs) with respect to modeling that supports the total system performance assessment (TSPA) for license application (LA) for a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either ''Included'' or ''Excluded'', is given for each FEP, along with the technical basis for the screening decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) in 10 CFR 63.114 (d, e, and f) [DIRS 156605]. The FEPs deal with UZ flow and radionuclide transport, including climate, surface water infiltration, percolation, drift seepage, and thermally coupled processes. This analysis summarizes the implementation of each FEP in TSPA-LA (that is, how the FEP is included) and also provides the technical basis for exclusion from TSPA-LA (that is, why the FEP is excluded). This report supports TSPA-LA.

  8. Efficient processing of transportation surveillance videos in the compressed domain

    NASA Astrophysics Data System (ADS)

    Bulan, Orhan; Bernal, Edgar A.; Loce, Robert P.

    2013-10-01

    Video surveillance is used extensively in intelligent transportation systems to enforce laws, collect tolls, and regularize traffic flow. Benefits to society include reduced fuel consumption and emissions, improved safety, and reduced traffic congestion. These video cameras installed at traffic lights, highways, toll booths, etc., continuously capture video and hence generate a vast amount of data that are stored in large databases. The captured video is typically compressed before being transmitted and/or stored. While all the archived information is present in the compressed video, most current applications operate on uncompressed video. The aim is to improve the efficiency of processing by utilizing features of the compression process and the compressed video stream. Key methods that are employed involve intelligent selection of reference frames (I-frames) and exploitation of the compression motion vectors. Although specific applications in the transportation imaging domain are presented, the methods proposed here can generally impact the ability to mine vast amounts of video data for usable information in many diverse settings. Applications presented include rapid search for target vehicles (Amber Alert, Silver Alert, stolen car, etc.), vehicle counting, stop sign/light enforcement, and vehicle speed estimation.

  9. Transport of active ellipsoidal particles in ratchet potentials

    SciTech Connect

    Ai, Bao-Quan Wu, Jian-Chun

    2014-03-07

    Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle destroys the directed transport. There exist optimized values of the parameters (the self-propelled velocity, the torque acting on the body) at which the average velocity takes its maximal value. For the ellipsoidal particle with not large asymmetric parameter, the average velocity decreases with increasing the rotational diffusion rate, while for the needlelike particle (very large asymmetric parameter), the average velocity is a peaked function of the rotational diffusion rate. By introducing a finite load, particles with different shapes (or different self-propelled velocities) will move to the opposite directions, which is able to separate particles of different shapes (or different self-propelled velocities)

  10. Active transport and cluster formation on 2D networks.

    PubMed

    Greulich, P; Santen, L

    2010-06-01

    We introduce a model for active transport on inhomogeneous networks embedded in a diffusive environment which is motivated by vesicular transport on actin filaments. In the presence of a hard-core interaction, particle clusters are observed that exhibit an algebraically decaying distribution in a large parameter regime, indicating the existence of clusters on all scales. The scale-free behavior can be understood by a mechanism promoting preferential attachment of particles to large clusters. The results are compared with a diffusion-limited aggregation model and active transport on a regular network. For both models we observe aggregation of particles to clusters which are characterized by a finite size scale if the relevant time scales and particle densities are considered. PMID:20556462

  11. Selective and Reversible Inhibition of Active CO2 Transport by Hydrogen Sulfide in a Cyanobacterium 1

    PubMed Central

    Espie, George S.; Miller, Anthony G.; Canvin, David T.

    1989-01-01

    The active transport of CO2 in the cyanobacterium Synechococcus UTEX 625 was inhibited by H2S. Treatment of the cells with up to 150 micromolar H2S + HS− at pH 8.0 had little effect on Na+-dependent HCO3− transport or photosynthetic O2 evolution, but CO2 transport was inhibited by more than 90%. CO2 transport was restored when H2S was removed by flushing with N2. At constant total H2S + HS− concentrations, inhibition of CO2 transport increased as the ratio of H2S to HS− increased, suggesting a direct role for H2S in the inhibitory process. Hydrogen sulfide does not appear to serve as a substrate for transport. In the presence of H2S and Na+ -dependent HCO3− transport, the extracellular CO2 concentration rose considerably above its equilibrium level, but was maintained far below its equilibrium level in the absence of H2S. The inhibition of CO2 transport, therefore, revealed an ongoing leakage from the cells of CO2 which was derived from the intracellular dehydration of HCO3− which itself had been recently transported into the cells. Normally, leaked CO2 is efficiently transported back into the cell by the CO2 transport system, thus maintaining the extracellular CO2 concentration near zero. It is suggested that CO2 transport not only serves as a primary means of inorganic carbon acquisition for photosynthesis but also serves as a means of recovering CO2 lost from the cell. A schematic model describing the relationship between the CO2 and HCO3− transport systems is presented. Images Figure 7 PMID:16667030

  12. Dopamine transporter occupancy by RTI-55, inhibition of dopamine transport and stimulation of locomotor activity

    SciTech Connect

    Gatley, S.J.; Gifford, A.N.; Volkow, N.D.

    1997-05-01

    Cocaine analogs such as RTI-55 (or {beta}CIT) with a higher affinity for the DAT are potentially useful as therapeutic drugs in cocaine abuse as well as for radiopharmaceutical use. Previously we showed that in mice RTI-55 (2 mg/Kg, i/p) reduced H-3 cocaine striatum-to-cerebellum ratios (St/Cb, {lg_bullet}) from 1.6 to 1.2 at 3 h after administration, with recovery by 12 h. In the present study we demonstrate a very similar time-course for transport {triangle} measured in striatal homo within 2 min of sacrifice. The maximum inhibition of uptake at about 1 h corresponded to about 80% of the control uptake rate, similar to the percent reduction in St/Cb. The time-course of the effect of this dose of RTI-55 on locomotor activity ({sq_bullet}) was complex, with a drop in the activity measure at 7 h, after a further injection of RTI-55, but activity remained higher than in saline controls. In spite of this complexity, which may be associated with stereotypies and/or exhaustion, the duration of increased activity is consistent with the duration of transporter blockade. These experiments support the notion that PET/SPECT measures of transporter occupancy accurately reflect transporter inhibition.

  13. Parental Factors in Children’s Active Transport to School

    PubMed Central

    Henne, Heather M.; Tandon, Pooja S.; Frank, Larry D.; Saelens, Brian E.

    2014-01-01

    Objective Identify non-distance factors related to children’s active transport (AT) to school, including parental, home, and environment characteristics. Understanding the factors related to children’s AT to school, beyond distance to school, could inform interventions to increase AT and children’s overall physical activity. Study Design Participants were in the Neighborhood Impact on Kids Study, a longitudinal, observational cohort study of children aged 6 - 11 and their parents in King County, WA and San Diego County, CA between 2007-2009. Parents reported frequency and mode of child transport to school, perceived neighborhood, home and family environments, parental travel behaviors, and sociodemographics. Methods Children living less than a 20 minute walk to school were in this analysis. Children classified as active transporters (walked/bicycled to or from school at least once per week) were compared with those not using AT as often. Results Children using AT were older and had parents who reported themselves using active transport. Having a family rule that restricts the child to stay within sight of the parent or home and more parent working hours was related to lower odds of a child using AT. Conclusions Children’s AT to school is associated with parental AT to work and other locations. Interventions should be considered that enable whole family AT, ameliorate safety concerns and decrease the need for parental supervision, such as walking school buses. PMID:24999161

  14. Macrophages require different nucleoside transport systems for proliferation and activation.

    PubMed

    Soler, C; García-Manteiga, J; Valdés, R; Xaus, J; Comalada, M; Casado, F J; Pastor-Anglada, M; Celada, A; Felipe, A

    2001-09-01

    To evaluate the mechanisms involved in macrophage proliferation and activation, we studied the regulation of the nucleoside transport systems. In murine bone marrow-derived macrophages, the nucleosides required for DNA and RNA synthesis are recruited from the extracellular medium. M-CSF induced macrophage proliferation and DNA and RNA synthesis, whereas interferon gamma (IFN-gamma) led to activation, blocked proliferation, and induced only RNA synthesis. Macrophages express at least the concentrative systems N1 and N2 (CNT2 and CNT1 genes, respectively) and the equilibrative systems es and ei (ENT1 and ENT2 genes, respectively). Incubation with M-CSF only up-regulated the equilibrative system es. Inhibition of this transport system blocked M-CSF-dependent proliferation. Treatment with IFN-gamma only induced the concentrative N1 and N2 systems. IFN-gamma also down-regulated the increased expression of the es equilibrative system induced by M-CSF. Thus, macrophage proliferation and activation require selective regulation of nucleoside transporters and may respond to specific requirements for DNA and RNA synthesis. This report also shows that the nucleoside transporters are critical for macrophage proliferation and activation. PMID:11532978

  15. Genetic and chemical reductions in protein phosphatase activity alter auxin transport, gravity response, and lateral root growth

    NASA Technical Reports Server (NTRS)

    Rashotte, A. M.; DeLong, A.; Muday, G. K.; Brown, C. S. (Principal Investigator)

    2001-01-01

    Auxin transport is required for important growth and developmental processes in plants, including gravity response and lateral root growth. Several lines of evidence suggest that reversible protein phosphorylation regulates auxin transport. Arabidopsis rcn1 mutant seedlings exhibit reduced protein phosphatase 2A activity and defects in differential cell elongation. Here we report that reduced phosphatase activity alters auxin transport and dependent physiological processes in the seedling root. Root basipetal transport was increased in rcn1 or phosphatase inhibitor-treated seedlings but showed normal sensitivity to the auxin transport inhibitor naphthylphthalamic acid (NPA). Phosphatase inhibition reduced root gravity response and delayed the establishment of differential auxin-induced gene expression across a gravity-stimulated root tip. An NPA treatment that reduced basipetal transport in rcn1 and cantharidin-treated wild-type plants also restored a normal gravity response and asymmetric auxin-induced gene expression, indicating that increased basipetal auxin transport impedes gravitropism. Increased auxin transport in rcn1 or phosphatase inhibitor-treated seedlings did not require the AGR1/EIR1/PIN2/WAV6 or AUX1 gene products. In contrast to basipetal transport, root acropetal transport was normal in phosphatase-inhibited seedlings in the absence of NPA, although it showed reduced NPA sensitivity. Lateral root growth also exhibited reduced NPA sensitivity in rcn1 seedlings, consistent with acropetal transport controlling lateral root growth. These results support the role of protein phosphorylation in regulating auxin transport and suggest that the acropetal and basipetal auxin transport streams are differentially regulated.

  16. Process Modeling of Flow, Transport, and Biodegradation in Landfill Bioreactors

    NASA Astrophysics Data System (ADS)

    Oldenburg, C. M.; Borglin, S. E.; Hazen, T. C.

    2001-12-01

    The need to control gas and leachate production and minimize refuse volume has motivated laboratory experiments and model development for design and assessment of bioremediation treatment processes. In parallel with landfill bioreactor laboratory experiments, we have developed T2LBM, a module for the TOUGH2 multiphase flow and transport simulator that implements a Landfill Bioreactor Model. T2LBM provides simulation capability for the processes of aerobic or anaerobic biodegradation of municipal solid waste and the associated three-dimensional flow and transport of gas, liquid, and heat through the refuse mass. T2LBM considers the components water, acetic acid, carbon dioxide, methane, oxygen, and nitrogen in aqueous and gas phases, with partitioning specified by temperature-dependent Henry's coefficients. T2LBM incorporates a Monod kinetic rate law for the exothermic biodegradation of acetic acid in the aqueous phase by either aerobic or anaerobic microbes as controlled by the local oxygen concentration. Methane and carbon dioxide generation due to biodegradation with corresponding thermal effects are modeled. Acetic acid is considered a proxy for all biodegradable substrates in the refuse. Aerobic and anaerobic microbes are assumed to be immobile and not limited by nutrients in their growth. Although a simplification of complex landfill processes, T2LBM shows reasonable agreement to published laboratory experiments of biodegradation and gas production depending on the choice of numerous input parameters. Simulations of the landfill bioreactor laboratory experiments show that the mechanistic approach of T2LBM can be used to model bioremediation assessment indicators such as oxygen consumption associated with respiration tests. This work was supported by Laboratory Directed Research and Development Funds at Lawrence Berkeley National Laboratory under Department of Energy Contract No. DE-AC03-76SF00098.

  17. Unraveling fatty acid transport and activation mechanisms in Yarrowia lipolytica.

    PubMed

    Dulermo, Rémi; Gamboa-Meléndez, Heber; Ledesma-Amaro, Rodrigo; Thévenieau, France; Nicaud, Jean-Marc

    2015-09-01

    Fatty acid (FA) transport and activation have been extensively studied in the model yeast species Saccharomyces cerevisiae but have rarely been examined in oleaginous yeasts, such as Yarrowia lipolytica. Because the latter begins to be used in biodiesel production, understanding its FA transport and activation mechanisms is essential. We found that Y. lipolytica has FA transport and activation proteins similar to those of S. cerevisiae (Faa1p, Pxa1p, Pxa2p, Ant1p) but mechanism of FA peroxisomal transport and activation differs greatly with that of S. cerevisiae. While the ScPxa1p/ScPxa2p heterodimer is essential for growth on long-chain FAs, ΔYlpxa1 ΔYlpxa2 is not impaired for growth on FAs. Meanwhile, ScAnt1p and YlAnt1p are both essential for yeast growth on medium-chain FAs, suggesting they function similarly. Interestingly, we found that the ΔYlpxa1 ΔYlpxa2 ΔYlant1 mutant was unable to grow on short-, medium-, or long-chain FAs, suggesting that YlPxa1p, YlPxa2p, and YlAnt1p belong to two different FA degradation pathways. We also found that YlFaa1p is involved in FA storage in lipid bodies and that FA remobilization largely depended on YlFat1p, YlPxa1p and YlPxa2p. This study is the first to comprehensively examine FA intracellular transport and activation in oleaginous yeast. PMID:25887939

  18. Engineering intracellular active transport systems as in vivo biomolecular tools.

    SciTech Connect

    Bachand, George David; Carroll-Portillo, Amanda

    2006-11-01

    Active transport systems provide essential functions in terms of cell physiology and metastasis. These systems, however, are also co-opted by invading viruses, enabling directed transport of the virus to and from the cell's nucleus (i.e., the site of virus replication). Based on this concept, fundamentally new approaches for interrogating and manipulating the inner workings of living cells may be achievable by co-opting Nature's active transport systems as an in vivo biomolecular tool. The overall goal of this project was to investigate the ability to engineer kinesin-based transport systems for in vivo applications, specifically the collection of effector proteins (e.g., transcriptional regulators) within single cells. In the first part of this project, a chimeric fusion protein consisting of kinesin and a single chain variable fragment (scFv) of an antibody was successfully produced through a recombinant expression system. The kinesin-scFv retained both catalytic and antigenic functionality, enabling selective capture and transport of target antigens. The incorporation of a rabbit IgG-specific scFv into the kinesin established a generalized system for functionalizing kinesin with a wide range of target-selective antibodies raised in rabbits. The second objective was to develop methods of isolating the intact microtubule network from live cells as a platform for evaluating kinesin-based transport within the cytoskeletal architecture of a cell. Successful isolation of intact microtubule networks from two distinct cell types was demonstrated using glutaraldehyde and methanol fixation methods. This work provides a platform for inferring the ability of kinesin-scFv to function in vivo, and may also serve as a three-dimensional scaffold for evaluating and exploiting kinesin-based transport for nanotechnological applications. Overall, the technology developed in this project represents a first-step in engineering active transport system for in vivo applications. Further

  19. Features, Events, and Processes in SZ Flow and Transport

    SciTech Connect

    K. Economy

    2004-11-16

    This analysis report evaluates and documents the inclusion or exclusion of the saturated zone (SZ) features, events, and processes (FEPs) with respect to modeling used to support the total system performance assessment (TSPA) for license application (LA) of a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either ''Included'' or ''Excluded'', is given for each FEP along with the technical basis for the decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.114 (d), (e), (f) (DIRS 156605). This scientific report focuses on FEP analysis of flow and transport issues relevant to the SZ (e.g., fracture flow in volcanic units, anisotropy, radionuclide transport on colloids, etc.) to be considered in the TSPA model for the LA. For included FEPs, this analysis summarizes the implementation of the FEP in TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded).

  20. Features, Events, and Processes in SZ Flow and Transport

    SciTech Connect

    S. Kuzio

    2005-08-20

    This analysis report evaluates and documents the inclusion or exclusion of the saturated zone (SZ) features, events, and processes (FEPs) with respect to modeling used to support the total system performance assessment (TSPA) for license application (LA) of a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either Included or Excluded, is given for each FEP along with the technical basis for the decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.11(d), (e), (f) [DIRS 173273]. This scientific report focuses on FEP analysis of flow and transport issues relevant to the SZ (e.g., fracture flow in volcanic units, anisotropy, radionuclide transport on colloids, etc.) to be considered in the TSPA model for the LA. For included FEPs, this analysis summarizes the implementation of the FEP in TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded).

  1. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  2. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  3. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  4. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  5. Analysis of Charge Carrier Transport in Organic Photovoltaic Active Layers

    NASA Astrophysics Data System (ADS)

    Han, Xu; Maroudas, Dimitrios

    2015-03-01

    We present a systematic analysis of charge carrier transport in organic photovoltaic (OPV) devices based on phenomenological, deterministic charge carrier transport models. The models describe free electron and hole transport, trapping, and detrapping, as well as geminate charge-pair dissociation and geminate and bimolecular recombination, self-consistently with Poisson's equation for the electric field in the active layer. We predict photocurrent evolution in devices with active layers of P3HT, P3HT/PMMA, and P3HT/PS, as well as P3HT/PCBM blends, and photocurrent-voltage (I-V) relations in these devices at steady state. Charge generation propensity, zero-field charge mobilities, and trapping, detrapping, and recombination rate coefficients are determined by fitting the modeling predictions to experimental measurements. We have analyzed effects of the active layer morphology for layers consisting of both pristine drop-cast films and of nanoparticle (NP) assemblies, as well as effects on device performance of insulating NP doping in conducting polymers and of specially designed interlayers placed between an electrode and the active layer. The model predictions provide valuable input toward synthesis of active layers with prescribed morphology that optimize OPV device performance.

  6. Modeling transport processes in sterilization-in-place.

    PubMed

    Noble, P T

    1992-01-01

    SIP (sterilization-in-place) of equipment using saturated steam is limited by transport processes that restrict the distribution of sterilizing steam. The following are two crucial operations: the removal of air prior to sterilization, and the removal of condensate during the sterilization. Using simple model systems of pipes and tanks, characteristic operating parameters were examined and steady-state models were analyzed. The results were used to evaluate design aspects of SIP, including heat insulation, spacing of steam traps, sloping of lines, steam velocities and consumption, placement of temperature sensors, and scale factors in piping. A more reliable SIP design is achievable by insulating equipment, spacing steam traps to limit condensate buildup, providing an effective air removal operation, and providing reliable, high-quality steam. PMID:1368451

  7. Processed sweet corn has higher antioxidant activity.

    PubMed

    Dewanto, Veronica; Wu, Xianzhong; Liu, Rui Hai

    2002-08-14

    Processed fruits and vegetables have been long considered to have lower nutritional value than the fresh produce due to the loss of vitamin C during processing. Vitamin C in apples has been found to contribute <0.4% of total antioxidant activity, indicating most of the activity comes from the natural combination of phytochemicals. This suggests that processed fruits and vegetables may retain their antioxidant activity despite the loss of vitamin C. Here it is shown that thermal processing at 115 degrees C for 25 min significantly elevated the total antioxidant activity of sweet corn by 44% and increased phytochemical content such as ferulic acid by 550% and total phenolics by 54%, although 25% vitamin C loss was observed. Processed sweet corn has increased antioxidant activity equivalent to 210 mg of vitamin C/100 g of corn compared to the remaining 3.2 mg of vitamin C in the sample that contributed only 1.5% of its total antioxidant activity. These findings do not support the notion that processed fruits and vegetables have lower nutritional value than fresh produce. This information may have a significant impact on consumers' food selection by increasing their consumption of fruits and vegetables to reduce the risk of chronic diseases. PMID:12166989

  8. Fluctuation driven active molecular transport in passive channel proteins

    NASA Astrophysics Data System (ADS)

    Kosztin, Ioan

    2006-03-01

    Living cells interact with their extracellular environment through the cell membrane, which acts as a protective permeability barrier for preserving the internal integrity of the cell. However, cell metabolism requires controlled molecular transport across the cell membrane, a function that is fulfilled by a wide variety of transmembrane proteins, acting as either passive or active transporters. In this talk it is argued that, contrary to the general belief, in active cell membranes passive and spatially asymmetric channel proteins can act as active transporters by consuming energy from nonequilibrium fluctuations fueled by cell metabolism. This assertion is demonstrated in the case of the E. coli aquaglyceroporin GlpF channel protein, whose high resolution crystal structure is manifestly asymmetric. By calculating the glycerol flux through GlpF within the framework of a stochastic model, it is found that, as a result of channel asymmetry, glycerol uptake driven by a concentration gradient is enhanced significantly in the presence of non-equilibrium fluctuations. Furthermore, the enhancement caused by a ratchet-like mechanism is larger for the outward, i.e., from the cytoplasm to the periplasm, flux than for the inward one, suggesting that the same non-equilibrium fluctuations also play an important role in protecting the interior of the cell against poisoning by excess uptake of glycerol. Preliminary data on water and sugar transport through aquaporin and maltoporin channels, respectively, are indicative of the universality of the proposed nonequilibrium-fluctuation-driven active transport mechanism. This work was supported by grants from the Univ. of Missouri Research Board, the Institute for Theoretical Sciences and the Department of Energy (DOE Contract W-7405-ENG-36), and the National Science Foundation (FIBR-0526854).

  9. Proton Gradients and Proton-Dependent Transport Processes in the Chloroplast.

    PubMed

    Höhner, Ricarda; Aboukila, Ali; Kunz, Hans-Henning; Venema, Kees

    2016-01-01

    Proton gradients are fundamental to chloroplast function. Across thylakoid membranes, the light induced -proton gradient is essential for ATP synthesis. As a result of proton pumping into the thylakoid lumen, an alkaline stromal pH develops, which is required for full activation of pH-dependent Calvin Benson cycle enzymes. This implies that a pH gradient between the cytosol (pH 7) and the stroma (pH 8) is established upon illumination. To maintain this pH gradient chloroplasts actively extrude protons. More than 30 years ago it was already established that these proton fluxes are electrically counterbalanced by Mg(2+), K(+), or Cl(-) fluxes, but only recently the first transport systems that regulate the pH gradient were identified. Notably several (Na(+),K(+))/H(+) antiporter systems where identified, that play a role in pH gradient regulation, ion homeostasis, osmoregulation, or coupling of secondary active transport. The established pH gradients are important to drive uptake of essential ions and solutes, but not many transporters involved have been identified to date. In this mini review we summarize the current status in the field and the open questions that need to be addressed in order to understand how pH gradients are maintained, how this is interconnected with other transport processes and what this means for chloroplast function. PMID:26973667

  10. Proton Gradients and Proton-Dependent Transport Processes in the Chloroplast

    PubMed Central

    Höhner, Ricarda; Aboukila, Ali; Kunz, Hans-Henning; Venema, Kees

    2016-01-01

    Proton gradients are fundamental to chloroplast function. Across thylakoid membranes, the light induced -proton gradient is essential for ATP synthesis. As a result of proton pumping into the thylakoid lumen, an alkaline stromal pH develops, which is required for full activation of pH-dependent Calvin Benson cycle enzymes. This implies that a pH gradient between the cytosol (pH 7) and the stroma (pH 8) is established upon illumination. To maintain this pH gradient chloroplasts actively extrude protons. More than 30 years ago it was already established that these proton fluxes are electrically counterbalanced by Mg2+, K+, or Cl- fluxes, but only recently the first transport systems that regulate the pH gradient were identified. Notably several (Na+,K+)/H+ antiporter systems where identified, that play a role in pH gradient regulation, ion homeostasis, osmoregulation, or coupling of secondary active transport. The established pH gradients are important to drive uptake of essential ions and solutes, but not many transporters involved have been identified to date. In this mini review we summarize the current status in the field and the open questions that need to be addressed in order to understand how pH gradients are maintained, how this is interconnected with other transport processes and what this means for chloroplast function. PMID:26973667

  11. Processing activities for STS-91 continue in OPF Bay 2

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Processing activities for STS-91 continue in KSC's Orbiter Processing Facility Bay 2. Two Get Away Special (GAS) canisters are shown after their installation into Discovery's payload bay. At left is G-648, an Canadian Space Agency-sponsored study of manufactured organic thin film by the physical vapor transport method, and the can on the right contains commemorative flags to be flown during the mission. STS-91 is scheduled to launch aboard the Space Shuttle Discovery for the ninth and final docking with the Russian Space Station Mir from KSC's Launch Pad 39A on June 2 with a launch window opening around 6:04 p.m. EDT.

  12. Measuring hydrodynamics and sediment transport processes in the Dee estuary

    NASA Astrophysics Data System (ADS)

    Bolaños, R.; Souza, A.

    2010-03-01

    The capability of monitoring and predicting the marine environment leads to a more sustainable development of coastal and offshore regions. Therefore, the continuous measurement of environmental processes become an important source of information. The present paper shows data collected during 6 years, and in particular during 2008, in the Dee Estuary. The data aims to improve the observations of the mobile sediments in coastal areas and its forcing hydrodynamics and turbulence. Data involves the deployment of instrumented rigs measuring sediment in suspension, currents, waves, sea level, sediment size and bedforms as well as cruise work including grab sampling, CTD profiles and side-scan sonar. The data covers flood and ebb tides during spring and neap periods with moderate and mild wave events, thus, having a good coverage of the processes needed to improve knowledge of sediment transport and the parameterizations used in numerical modelling. The data, in raw and treated, is being banked at BODC (British Oceanographic Data Centre, http://www.bodc.ac.uk/) which is the formal British organization for looking after and distributing data concerning the marine environment.

  13. Measuring hydrodynamics and sediment transport processes in the Dee Estuary

    NASA Astrophysics Data System (ADS)

    Bolaños, R.; Souza, A.

    2010-06-01

    The capability of monitoring and prediction in the marine environment provides information that may allow sustainable development of coastal and offshore regions. Therefore, the continuous measurement of environmental processes becomes an important source of information. The present paper shows data collected during 6 years, and in particular during 2008, in the Dee Estuary. The aim of the data collection is to improve the observations of the mobile sediments in coastal areas and its forcing hydrodynamics and turbulence. Data includes information from the deployment of instrumented rigs measuring sediment in suspension, currents, waves, sea level, sediment size and bedforms as well as cruise work including grab sampling, CTD profiles and side-scan sonar. The data cover flood and ebb tides during spring and neap periods with moderate and mild wave events, thus, having a good coverage of the processes needed to improve knowledge of sediment transport and the parameterizations used in numerical modelling. The data, in raw and treated, are being banked at BODC (British Oceanographic Data Centre, http://www.bodc.ac.uk/) which is the formal British organization for looking after and distributing data concerning the marine environment.

  14. Analysis of the irreversible process of proton transport in the purple membrane of Halobacterium halobium.

    PubMed

    Hong, T; Manqi, T

    1980-04-01

    The proton transport across biological membrane, accompanied by energy transformation, is closely related with many basic processes involved in the maintenance of life. Active researches are carried out in this field, but so far we have not known a complete calculation. This paper presents a model of an open and closed photon-controlled ion pore with a quantitative analysis of the irreversible process of the proton transport across the purple membrane. Upon absorbing photon by the purple membrane, the deprotonation of the Schiff base causes the ion pore to open, but it will close when it returns to bR570. A set of nonlinear differential equations describing this model is given. The stability of the equations is discussed. The results of the numerical calculation for steady state are found in good agreement with the experimental data of Bakker. PMID:6250213

  15. Transport activity of chimaeric AE2-AE3 chloride/bicarbonate anion exchange proteins.

    PubMed Central

    Fujinaga, Jocelyne; Loiselle, Frederick B; Casey, Joseph R

    2003-01-01

    Chloride/bicarbonate anion exchangers (AEs), found in the plasma membrane of most mammalian cells, are involved in pH regulation and bicarbonate metabolism. Although AE2 and AE3 are highly similar in sequence, AE2-transport activity was 10-fold higher than AE3 (41 versus 4 mM x min(-1) respectively), when expressed by transient transfection of HEK-293 cells. AE2-AE3 chimaeras were constructed to define the region responsible for differences in transport activity. The level of AE2 expression was approx. 30% higher than that of AE3. Processing to the cell surface, studied by chemical labelling and confocal microscopy, showed that AE2 is processed to the cell surface approx. 8-fold more efficiently than AE3. The efficiency of cell-surface processing was dependent on the cytoplasmic domain, since the AE2 domain conferred efficient processing upon the AE3 membrane domain, with a predominant role for amino acids 322-677 of AE2. AE2 that was expressed in HEK-293 cells was glycosylated, but little of AE3 was. However, AE2 expressed in the presence of the glycosylation inhibitor, tunicamycin, was not glycosylated, yet retained 85 +/- 8% of anion-transport activity. Therefore glycosylation has little, if any, role in the cell-surface processing or activity of AE2 or AE3. We conclude that the low anion-transport activity of AE3 in HEK-293 cells is due to low level processing to the plasma membrane, possibly owing to protein interactions with the AE3 cytoplasmic domain. PMID:12578559

  16. Hydrologic processes controlling herbicide transport in a Missouri claypan watershed

    NASA Astrophysics Data System (ADS)

    Liu, F.; Lerch, R.; Baffaut, C.; Yang, J.; Sadler, J.

    2011-12-01

    Hydrologic processes controlling herbicide transport are still poorly understood for claypan watersheds in the US Midwest. The presence of a near-surface claypan, a restrictive soil layer of smectitic mineralogy, may play a critical role in controlling herbicide transport to stream water. Data from Goodwater Creek Experimental Watershed (GCEW) (area = 72.5 km2) in central Missouri indicate that atrazine concentrations in stream water peaked during spring storm events, but high concentrations persisted in the baseflow following these events for days to weeks. It is hypothesized that hydrologic pathways exert a major control on atrazine concentrations in stream water. The hypothesis is tested using a combination of a statistical hydrograph model developed by Washington University in Saint Louis using Darcy's law and the diffusion equation and orthogonal data such as electric conductivity (EC). The basin time constant, the single fitting parameter for the model, was approximately 600 minutes or 0.4 days for GCEW. This value is similar to those for other small, non-claypan watersheds in Missouri. Stream flows were simulated very well by the model during the rising limbs of hydrographs for GCEW. Unlike other Missouri watersheds without claypan soils, stream flows in this claypan watershed were always significantly over-predicted for the prolonged falling tails, indicating a possible strong evapotranspiration effect during baseflow. EC values in shallow subsurface water indeed became much higher during baseflow than during storm events, consistent with the evapotranspiration effect on shallow subsurface water. These results suggests that both hydrologic pathways and evapotranspiration exert a major control on stream water quality in Goodwater Creek Experimental Watershed.

  17. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  18. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  19. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  20. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  1. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  2. A fully resolved active musculo-mechanical model for esophageal transport

    NASA Astrophysics Data System (ADS)

    Kou, Wenjun; Bhalla, Amneet Pal Singh; Griffith, Boyce E.; Pandolfino, John E.; Kahrilas, Peter J.; Patankar, Neelesh A.

    2015-10-01

    Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multi-layered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, and the esophagus is modeled as an actively contracting, fiber-reinforced tube. Before considering the full model of the esophagus, however, we first consider a standard benchmark problem of flow past a cylinder. Next a simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Finally, three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation into an integrated model. Consistent with experimental observations, our simulations capture the pressure peak generated by the muscle activation pulse that travels along the bolus tail. These fully resolved simulations provide new insights into roles of the mucosal layers during bolus transport. In addition, the information on pressure and the kinematics of the esophageal wall resulting from the coordination of muscle activation is provided, which may help relate clinical data from manometry and ultrasound images to the underlying esophageal motor function.

  3. 78 FR 68908 - Proposed Information Collection (Veterans Transportation Service Data Collection); Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-15

    ... AFFAIRS Proposed Information Collection (Veterans Transportation Service Data Collection); Activity... needed to evaluate the Veterans Transportation Service Data Collection program to ensure Veterans... Control No. 2900-NEW (Veterans Transportation Service Data Collection)'' in any correspondence. During...

  4. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Y.; Sartorius, M.; Busch, A.; Krooss, B. M.; Littke, R.

    2012-12-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a subbituminous A coal from the Surat Basin, Queensland Australia (figure). From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg-corrected permeability depends on gas type. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa, with increasing mean pore pressure at lower confining pressure an increase in permeability is observed, which is attributed to a widening of cleat aperture. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane and CO2. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals was significantly lower (by 50%) than that of dry coals, no hysteresis was observed between sorption and desorption on dry and moisture-equilibrated samples and the

  5. Decision process involved in preparing the Shippingport reactor pressure vessel for transport

    SciTech Connect

    Murphie, W.E.

    1989-01-01

    The most significant part of the Shippingport Station Decommissioning Project was the one-piece removal and shipment of the reactor pressure vessel (RPV). Implicit in the RPV transport was the task of qualifying the RPV as a waste package acceptable for shipment. Soon after physical decommissioning began on September 1985, questions regarding the packaging certification and transport of the RPV from Shippingport, Pennsylvania to the US Department of Energy (DOE) Hanford Waste Burial Site necessitated reexamination of several planning assumptions. A complete reassessment of the regulatory requirements governing the RPV shipment resulted in a programmatic decision to obtain a type B(U) Certificate of Compliance and abandon the originally planned US Department of Transportation (DOT) low specific activity (LSA) shipment. The decision process resulting in this conclusion was extensive and involved many organizations and agencies. Incidental to this process, several subtle certification issues were identified that required resolution. Some of these issues involved the definition of LSA material for large packages; interpretation and compliance with DOE, DOT and US Nuclear Regulatory Commission (NRC) regulations for the transport of radioactive material; incorporation of the International Atomic Energy Agency (IAEA) regulations by the Panama Canal; and DOE policy requiring advance notification to states of radioactive waste shipments. 2 figs.

  6. The role of the soil-root interface for transport processes in soils.

    NASA Astrophysics Data System (ADS)

    Vanderborght, J.; Schröder, N.; Garre, S.; Javaux, M.; Haber-Pohlmeier, S.; Pohlmeier, A. J.; Vereecken, H.

    2011-12-01

    Transport processes in soils are known to be strongly influenced by soil heterogeneity, which leads to a spatially variable flow field. Also plants, which take up water from the root zone, have an important impact on the flow field and therefore on solute transport processes. In order to describe the impact of plant water uptake on the flow field, water flow in the soil-plant system has to be simulated in an integrated way. The simulation models R-SWMS and PARTRACE (Javaux et al., 2008) couple 3-D water flow in the soil with flow in a plant root network and simulate solute transport using particle tracking. Using this model, the impact of root architecture, plant solute uptake mechanisms: passive, active and solute exclusion, and plant transpiration rate, on the water flow field in the soil and on solute dispersion was simulated. Root water uptake induces small-scale variations in the water flow field which increases solute dispersion. For the case that solutes are not taken up by plant roots but excluded, the simulations suggest that part of the applied solute mass is immobilized at the soil-root interface. This immobilisation results in lower effluent concentrations than would be expected from simulations with a 1-D transport model. Tracer experiments at two different scales: the small column scale with a single plant in packed sand and the lysimeter scale with a set of plants in an undisturbed large soil monolith, were conducted to validate the simulation studies. At the small column scale, transport of a Gd tracer and the root network were imaged using MRI. At the lysimeter scale, transport of a salt tracer was monitored by measuring tracer concentrations in the effluent of the lysimeter. Javaux, M., T. Schröder, J. Vanderborght, and H. Vereecken. 2008. Use of a three-dimensional detailed modeling approach for predicting root water uptake. Vadose Zone J. 7:1079-1088.doi: 10.2136/vzj2007.0115.

  7. Differences in associations between active transportation and built environmental exposures when expressed using different components of individual activity spaces.

    PubMed

    van Heeswijck, Torbjorn; Paquet, Catherine; Kestens, Yan; Thierry, Benoit; Morency, Catherine; Daniel, Mark

    2015-05-01

    This study assessed relationships between built environmental exposures measured within components of individual activity spaces (i.e., travel origins, destinations and paths in-between), and use of active transportation in a metropolitan setting. Individuals (n=37,165) were categorised as using active or sedentary transportation based on travel survey data. Generalised Estimating Equations analysis was used to test relationships with active transportation. Strength and significance of relationships between exposures and active transportation varied for different components of the activity space. Associations were strongest when including travel paths in expression of the built environment. Land use mix and greenness were negatively related to active transportation. PMID:25862996

  8. 23 CFR 450.306 - Scope of the metropolitan transportation planning process.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... CFR part 940. (g) Preparation of the coordinated public transit-human services transportation plan, as... Programming § 450.306 Scope of the metropolitan transportation planning process. (a) The...

  9. The contribution of an overlooked transport process to a wetland's methane emissions

    NASA Astrophysics Data System (ADS)

    Poindexter, Cristina M.; Baldocchi, Dennis D.; Matthes, Jaclyn Hatala; Knox, Sara Helen; Variano, Evan A.

    2016-06-01

    Wetland methane transport processes affect what portion of methane produced in wetlands reaches the atmosphere. We model what has been perceived to be the least important of these transport processes: hydrodynamic transport of methane through wetland surface water and show that its contribution to total methane emissions from a temperate freshwater marsh is surprisingly large. In our 1 year study, hydrodynamic transport comprised more than half of nighttime methane fluxes and was driven primarily by water column thermal convection occurring overnight as the water surface cooled. Overall, hydrodynamic transport was responsible for 32% of annual methane emissions. Many methane models have overlooked this process, but our results show that wetland methane fluxes cannot always be accurately described using only other transport processes (plant-mediated transport and ebullition). Modifying models to include hydrodynamic transport and the mechanisms that drive it, particularly convection, could help improve predictions of future wetland methane emissions.

  10. The role of Na/+/ in transport processes of bacterial membranes

    NASA Technical Reports Server (NTRS)

    Lanyi, J. K.

    1979-01-01

    Until recently it was generally held that transport in bacteria was linked exclusively to proton circulation, in contrast to most eucaryotic systems, which depended on Na(+) circulation. The present review is intended to trace recent developments which have led to the discarding of this idea. The discussion covers transport of Na(+) and other cations, effects of Na(+) and Na(+) gradients on metabolite transport, properties of Na(+)-dependent transport carriers, and evolutionary considerations of Na(+) transport. It is now apparent that the transport of Na(+) is an important part of energy metabolism in bacteria, and that Na(+) gradients as well as H(+) gradients are used in these systems for the conservation and transmission of energy. Two hypotheses are proposed to explain the evolution of Na/K systems, and it is presently difficult to decide between them.

  11. Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

    NASA Astrophysics Data System (ADS)

    Annewandter, Robert

    2014-05-01

    The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced gas transport and subsequent soil gas sampling during On-Site inspections. Generally, gas transport has been widely studied with different numerical codes. However, gas transport of radioxenons and radioiodines in the post-detonation regime and their possible fractionation is still neglected in the open peer-reviewed literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the multiple isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radionuclides, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different mass diffusivities due to mass differences between the radionuclides. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures or highly conductive faults which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a so-called ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which is recognized by the oil industry as leading in Discrete Fracture-Matrix (DFM) simulations. It has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations, fracture propagation in fractured, porous media, and Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite

  12. Mechanistic determinants of the directionality and energetics of active export by a heterodimeric ABC transporter

    NASA Astrophysics Data System (ADS)

    Grossmann, Nina; Vakkasoglu, Ahmet S.; Hulpke, Sabine; Abele, Rupert; Gaudet, Rachelle; Tampé, Robert

    2014-11-01

    The ATP-binding cassette (ABC) transporter associated with antigen processing (TAP) participates in immune surveillance by moving proteasomal products into the endoplasmic reticulum (ER) lumen for major histocompatibility complex class I loading and cell surface presentation to cytotoxic T cells. Here we delineate the mechanistic basis for antigen translocation. Notably, TAP works as a molecular diode, translocating peptide substrates against the gradient in a strict unidirectional way. We reveal the importance of the D-loop at the dimer interface of the two nucleotide-binding domains (NBDs) in coupling substrate translocation with ATP hydrolysis and defining transport vectoriality. Substitution of the conserved aspartate, which coordinates the ATP-binding site, decreases NBD dimerization affinity and turns the unidirectional primary active pump into a passive bidirectional nucleotide-gated facilitator. Thus, ATP hydrolysis is not required for translocation per se, but is essential for both active and unidirectional transport. Our data provide detailed mechanistic insight into how heterodimeric ABC exporters operate.

  13. Active and passive calcium transport systems in plant cells. Progress report, May 1986--January 1991

    SciTech Connect

    Sze, H.

    1991-12-31

    The ability to change cytoplasmic Ca{sup 2+} levels ([Ca{sup 2+}]) by cells has made this cation a key regulator of many biological processes. Cytoplasmic [Ca{sup 2+}] is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic [Ca{sup 2+}] and active Ca{sup 2+} transport systems that lower cytosolic [Ca{sup 2+}]. The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells.

  14. Convection in the Physical Vapor Transport Process. Part 2; Thermosolutal

    NASA Technical Reports Server (NTRS)

    Duval, Walter M. B.

    1994-01-01

    We consider the effect of an inert gas on the diffusive-convective physical vapor transport process. We investigate the case when the temperature gradient is stabilizing and the concentration gradient is destabilizing for a wide parametric range. When an inert gas is present, the thermal and solutal convection oppose each other. The solutal field is destabilizing while the thermal field and the advective-diffusive flux stabilize the flow field. When the pressure of the inert component is increased, the stabilizing effect of the advective-diffusive flux is decreased. The intensity of convection as well as the oscillatory transient time increases. Below, the critical Rayleigh number, the nonlinear dynamics of the flow field show an oscillatory approach to steady state. For parametric values in the neighborhood of the critical Rayleigh number, the flow field undergoes a chaotic transient which settles to a periodic state. The asymptotic state of the flow field shows that growth and amalgamation of cells yields an overturning motion which results in an asymmetric cellular structure. The low gravity environment yields the stabilizing advective-diffusive flow which results in uniform temperature and concentration gradients near the crystal interface.

  15. Transport processes and interfacial phenomena in an evaporating meniscus

    SciTech Connect

    Sujanani, M.; Wayner, P.C. Jr.

    1991-01-01

    When a liquid film wets a solid surface, a contact line region is formed where the vapor, liquid and solid phases are in close proximity. The film thickness in this region varies from about 10 {mu}m (Capillary Meniscus) to less than about 100 nm (Adsorbed film). In addition to being functions of temperature and pressure (as for a bulk phase), the thermodynamic properties (e.g., chemical potential) of these thin films depend on their shape (curvature) and thickness due to surface forces. The coupled transport processes and interfacial phenomena occurring in this microscopic region are also controlled by these surface forces. The objective of this paper is to report experimental data which complement earlier analytical models of this region. The experimental setup consists of a flat silicon plate partially immersed at a small angle, {theta}, in a pool of liquid. The plate is in a closed cell and a spreading liquid (1,1,2-Trichlorotrifluoro ethane), in equilibrium with its own vapor, forms a zero contact angle with the plate. The plate can be electrically heated at the upper end by supplying power to a thin, rectangular platinum heater which is painted on the backside of the silicon wafer. The meniscus thickness profile, which is related to the effective pressure in the liquid, was used as a probe for understanding the sensitivity of the meniscus to the non-equilibrium effects associated with evaporation/condensation mechanisms. 5 refs., 8 figs.

  16. Space Transportation System Liftoff Debris Mitigation Process Overview

    NASA Technical Reports Server (NTRS)

    Mitchell, Michael; Riley, Christopher

    2011-01-01

    Liftoff debris is a top risk to the Space Shuttle Vehicle. To manage the Liftoff debris risk, the Space Shuttle Program created a team with in the Propulsion Systems Engineering & Integration Office. The Shutt le Liftoff Debris Team harnesses the Systems Engineering process to i dentify, assess, mitigate, and communicate the Liftoff debris risk. T he Liftoff Debris Team leverages off the technical knowledge and expe rtise of engineering groups across multiple NASA centers to integrate total system solutions. These solutions connect the hardware and ana lyses to identify and characterize debris sources and zones contribut ing to the Liftoff debris risk. The solutions incorporate analyses sp anning: the definition and modeling of natural and induced environmen ts; material characterizations; statistical trending analyses, imager y based trajectory analyses; debris transport analyses, and risk asse ssments. The verification and validation of these analyses are bound by conservative assumptions and anchored by testing and flight data. The Liftoff debris risk mitigation is managed through vigilant collab orative work between the Liftoff Debris Team and Launch Pad Operation s personnel and through the management of requirements, interfaces, r isk documentation, configurations, and technical data. Furthermore, o n day of launch, decision analysis is used to apply the wealth of ana lyses to case specific identified risks. This presentation describes how the Liftoff Debris Team applies Systems Engineering in their proce sses to mitigate risk and improve the safety of the Space Shuttle Veh icle.

  17. Deformational mass transport and invasive processes in soil evolution

    NASA Technical Reports Server (NTRS)

    Brimhall, George H.; Chadwick, Oliver A.; Lewis, Chris J.; Compston, William; Williams, Ian S.; Danti, Kathy J.; Dietrich, William E.; Power, Mary E.; Hendricks, David; Bratt, James

    1992-01-01

    Channels left in soil by decayed roots and burrowing animals allow organic and inorganic precipitates and detritus to move through soil from above, to depths at which the minuteness of pores restricts further passage. Consecutive translocation-and-root-growth phases stir the soil, constituting an invasive, dilatational process which generates cumulative strains. Below the depths thus affected, mineral dissolution by descending organic acids leads to internal collapse; this softened/condensed precursor horizon is then transformed into soil via biological activity that mixes and expands the evolving residuum through root and micropore-network invasion.

  18. Energy loss in a partonic transport model including bremsstrahlung processes

    SciTech Connect

    Fochler, Oliver; Greiner, Carsten; Xu Zhe

    2010-08-15

    A detailed investigation of the energy loss of gluons that traverse a thermal gluonic medium simulated within the perturbative QCD-based transport model BAMPS (a Boltzmann approach to multiparton scatterings) is presented in the first part of this work. For simplicity the medium response is neglected in these calculations. The energy loss from purely elastic interactions is compared with the case where radiative processes are consistently included based on the matrix element by Gunion and Bertsch. From this comparison, gluon multiplication processes gg{yields}ggg are found to be the dominant source of energy loss within the approach employed here. The consequences for the quenching of gluons with high transverse momentum in fully dynamic simulations of Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC) energy of {radical}(s)=200A GeV are discussed in the second major part of this work. The results for central collisions as discussed in a previous publication are revisited, and first results on the nuclear modification factor R{sub AA} for noncentral Au+Au collisions are presented. They show a decreased quenching compared to central collisions while retaining the same shape. The investigation of the elliptic flow v{sub 2} is extended up to nonthermal transverse momenta of 10 GeV, exhibiting a maximum v{sub 2} at roughly 4 to 5 GeV and a subsequent decrease. Finally the sensitivity of the aforementioned results on the specific implementation of the effective modeling of the Landau-Pomeranchuk-Migdal (LPM) effect via a formation-time-based cutoff is explored.

  19. Ride On! Mini-Units and Learning Activities on Public Transportation for Grades 6 through 9.

    ERIC Educational Resources Information Center

    Finn, Peter; And Others

    One of a series of eleven curriculum manuals which cover the four transportation topics of public transportation, transportation and the environment, transportation safety, and bicycles for elementary, secondary, and adult levels, this manual covers the public transportation topic for grades 6-9. It contains forty-two learning activities grouped…

  20. Ride On! Mini-Units and Learning Activities on Public Transportation for Grades 9 through 12.

    ERIC Educational Resources Information Center

    Finn, Peter; And Others

    One of a series of eleven curriculum manuals which cover the four transportation topics of public transportation, transportation and the environment, transportation safety, and bicycles for elementary, secondary, and adult levels, this manual covers the public transportation topic for grades 9-12. It contains forty-nine learning activities grouped…

  1. Simulation of reactive processes related to biodegradation in aquifers. 1. Structure of the three-dimensional reactive transport model

    NASA Astrophysics Data System (ADS)

    Schäfer, Dirk; Schäfer, Wolfgang; Kinzelbach, Wolfgang

    1998-05-01

    The reactive transport model TBC (transport, biochemistry, and chemistry) numerically solves the equations for reactive transport in three-dimensional saturated groundwater flow. A finite element approximation and a standard Galerkin method are used. Solute transport is coupled to microbially mediated organic carbon degradation. Microbial growth is assumed to follow Monod-type kinetics. Substrate consumption and release of metabolic products is coupled to microbial growth via yield coefficients and stoichiometric relations. Additionally, the effects of microbial activity on selected inorganic chemical species in the aquifer can be considered. TBC allows the user to specify a wide range of possible biochemical and chemical reactions in the input file. This makes TBC a powerful and flexible simulation tool. It was developed to simulate reactive processes related to in situ bioremediation, but further fields of application are laboratory column studies on redox processes coupled to organic carbon degradation, field cases of intrinsic biodegradation, and early diagenetic processes in sediments.

  2. Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity

    PubMed Central

    Kasess, Christian H.; Meyer, Bernhard M.; Hofmaier, Tina; Diers, Kersten; Bartova, Lucie; Pail, Gerald; Huf, Wolfgang; Uzelac, Zeljko; Hartinger, Beate; Kalcher, Klaudius; Perkmann, Thomas; Haslacher, Helmuth; Meyer-Lindenberg, Andreas; Kasper, Siegfried; Freissmuth, Michael; Windischberger, Christian; Willeit, Matthäus; Lanzenberger, Rupert; Esterbauer, Harald; Brocke, Burkhard; Moser, Ewald; Sitte, Harald H.; Pezawas, Lukas

    2014-01-01

    Background The serotonin transporter (5-HTT) is abundantly expressed in humans by the serotonin transporter gene SLC6A4 and removes serotonin (5-HT) from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence. Methods A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (Vmax) was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA) to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD) activity and platelet Vmax. Results The present study demonstrates that increases in platelet Vmax significantly predict default-mode network (DMN) suppression in healthy subjects independent of genetic variation within SLC6A4. Furthermore, functional connectivity analyses indicate that platelet Vmax is related to global DMN activation and not intrinsic DMN connectivity. Conclusion This study provides evidence that platelet Vmax predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal Vmax coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation. PMID:24667541

  3. Studies of thunderstorm transport processes with aircraft using tracer techniques

    SciTech Connect

    Detwiler, A.G.; Smith, P.L.; Stith, J.L.

    1996-10-01

    Instrumented aircraft can provide in situ measurements of winds and turbulence useful for studying transport and dispersion in clouds. Using inert artificial gases as tracers, and fast response analyzers on aircraft, time-resolved observations of transport and dispersion have been obtained. Examples are shown of these types of observations in and around cumulus and cumulonimbus clouds. 23 refs., 6 figs.

  4. Processing of Color Words Activates Color Representations

    ERIC Educational Resources Information Center

    Richter, Tobias; Zwaan, Rolf A.

    2009-01-01

    Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

  5. Acetaminophen inhibits intestinal p-glycoprotein transport activity.

    PubMed

    Novak, Analia; Carpini, Griselda Delli; Ruiz, María Laura; Luquita, Marcelo G; Rubio, Modesto C; Mottino, Aldo D; Ghanem, Carolina I

    2013-10-01

    Repeated acetaminophen (AP) administration modulates intestinal P-glycoprotein (P-gp) expression. Whether AP can modulate P-gp activity in a short-term fashion is unknown. We investigated the acute effect of AP on rat intestinal P-gp activity in vivo and in vitro. In everted intestinal sacs, AP inhibited serosal-mucosal transport of rhodamine 123 (R123), a prototypical P-gp substrate. R123 efflux plotted against R123 concentration adjusted well to a sigmoidal curve. Vmax decreased 50% in the presence of AP, with no modification in EC50, or slope, ruling out the possibility of inhibition to be competitive. Inhibition by AP was absent at 0°C, consistent with interference of the active transport of R123 by AP. Additionally, AP showed no effect on normal localization of P-gp at the apical membrane of the enterocyte and neither affected paracellular permeability. Consistent with absence of a competitive inhibition, two further strategies strongly suggested that AP is not a P-gp substrate. First, serosal-mucosal transport of AP was not affected by the classical P-gp inhibitors verapamil or Psc 833. Second, AP accumulation was not different between P-gp knock-down and wild-type HepG2 cells. In vivo intestinal absorption of digoxin, another substrate of P-gp, was assessed in the presence or absence of AP (100 μM). Portal digoxin concentration was increased by 214%, in average, by AP, as compared with digoxin alone. In conclusion, AP inhibited P-gp activity, increasing intestinal absorption of digoxin, a prototypical substrate. These results suggest that therapeutic efficacy of P-gp substrates can be altered if coadministered with AP. PMID:23897240

  6. Theory and Simulation of Neoclassical Transport Processes, with Local Trapping

    SciTech Connect

    Dubin, Daniel H. E.

    2009-03-30

    Neoclassical transport is studied using idealized simulations that follow guiding centers in given fields, neglecting collective effects on the plasma evolution, but including collisions at rate {nu}. For simplicity the magnetic field is assumed to be uniform; transport is due to asymmetries in applied electrostatic fields. Also, the Fokker-Planck equation describing the particle distribution is solved, and the predicted transport is found to agree with the simulations. Banana, plateau, and fluid regimes are identified and observed in the simulations. When separate trapped particle populations are created by application of an axisymmetric squeeze potential, enhanced transport regimes are observed, scaling as {radical}({nu}) when {nu}<{omega}{sub 0}<{omega}{sub b} and as 1/{nu} when {omega}{sub 0}<{nu}<{omega}{sub b} where {omega}{sub 0} and {omega}{sub b} are the rotation and axial bounce frequencies, respectively. These regimes are similar to those predicted for neoclassical transport in stellarators.

  7. Laboratory studies of aeolian sediment transport processes on planetary surfaces

    NASA Astrophysics Data System (ADS)

    Rasmussen, Keld R.; Valance, Alexandre; Merrison, Jonathan

    2015-09-01

    , but not all, older or recent wind tunnel observations. Similarly some measurements performed with uniform sand samples having grain diameters of the order of 0.25-0.40 mm indicate that ripple spacing depends on friction velocity in a similar way as particle jump length. The observations are thus in agreement with a recent ripple model that link the typical jump length to ripple spacing. A possible explanation for contradictory observations in some experiments may be that long observation sequences are required in order to assure that equilibrium exists between ripple geometry and wind flow. Quantitative understanding of saltation characteristics on Mars still lacks important elements. Based upon image analysis and numerical predictions, aeolian ripples have been thought to consist of relatively large grains (diameter > 0.6 mm) and that saltation occurs at high wind speeds (> 26 m/s) involving trajectories that are significantly longer than those on Earth (by a factor of 10-100). However, this is not supported by recent observations from the surface of Mars, which shows that active ripples in their geometry and composition have characteristics compatible with those of terrestrial ripples (Sullivan et al., 2008). Also the highest average wind speeds on Mars have been measured to be < 20 m/s, with even turbulent gusts not exceeding 25 m/s. Electrification is seen as a dominant factor in the transport dynamics of dust on Mars, affecting the structure, adhesive properties and detachment/entrainment mechanisms specifically through the formation of aggregates (Merrison et al., 2012). Conversely for terrestrial conditions electric fields typically observed are not intense enough to significantly affect sand transport rates while little is known in the case of extra-terrestrial environments.

  8. Curcumin directly inhibits the transport activity of GLUT1

    PubMed Central

    Gunnink, Leesha K.; Alabi, Ola D.; Kuiper, Benjamin D.; Gunnink, Stephen M.; Schuiteman, Sam J.; Strohbehn, Lauren E.; Hamilton, Kathryn E.; Wrobel, Kathryn E.; Louters, Larry L.

    2016-01-01

    Curcumin, a major ingredient in turmeric, has a long history of medicinal applications in a wide array of maladies including treatment for diabetes and cancer. Seemingly counterintuitive to the documented hypoglycemic effects of curcumin, however, a recent report indicates that curcumin directly inhibits glucose uptake in adipocytes. The major glucose transporter in adipocytes is GLUT4. Therefore, this study investigates the effects of curcumin in cell lines where the major transporter is GLUT1. We report that curcumin has an immediate inhibitory effect on basal glucose uptake in L929 fibroblast cells with a maximum inhibition of 80% achieved at 75 μM curcumin. Curcumin also blocks activation of glucose uptake by azide, glucose deprivation, hydroxylamine, or phenylarsine oxide. Inhibition does not increase with exposure time and the inhibitory effects reverse within an hour. Inhibition does not appear to involve a reaction between curcumin and the thiol side chain of a cysteine residue since neither prior treatment of cells with iodoacetamide nor curcumin with cysteine alters curcumin’s inhibitory effects. Curcumin is a mixed inhibitor reducing the Vmax of 2DG transport by about half with little effect on the Km. The inhibitory effects of curcumin are not additive to the effects of cytochalasin B and 75 μM curcumin actually reduces specific cytochalasin B binding by 80%. Taken together, the data suggest that curcumin binds directly to GLUT1 at a site that overlaps with the cytochalasin B binding site and thereby inhibits glucose transport. A direct inhibition of GLUT proteins in intestinal epithelial cells would likely reduce absorption of dietary glucose and contribute to a hypoglycemic effect of curcumin. Also, inhibition of GLUT1 activity might compromise cancer cells that overexpress GLUT1 and be another possible mechanism for the documented anticancer effects of curcumin. PMID:27039889

  9. Curcumin directly inhibits the transport activity of GLUT1.

    PubMed

    Gunnink, Leesha K; Alabi, Ola D; Kuiper, Benjamin D; Gunnink, Stephen M; Schuiteman, Sam J; Strohbehn, Lauren E; Hamilton, Kathryn E; Wrobel, Kathryn E; Louters, Larry L

    2016-06-01

    Curcumin, a major ingredient in turmeric, has a long history of medicinal applications in a wide array of maladies including treatment for diabetes and cancer. Seemingly counterintuitive to the documented hypoglycemic effects of curcumin, however, a recent report indicates that curcumin directly inhibits glucose uptake in adipocytes. The major glucose transporter in adipocytes is GLUT4. Therefore, this study investigates the effects of curcumin in cell lines where the major transporter is GLUT1. We report that curcumin has an immediate inhibitory effect on basal glucose uptake in L929 fibroblast cells with a maximum inhibition of 80% achieved at 75 μM curcumin. Curcumin also blocks activation of glucose uptake by azide, glucose deprivation, hydroxylamine, or phenylarsine oxide. Inhibition does not increase with exposure time and the inhibitory effects reverse within an hour. Inhibition does not appear to involve a reaction between curcumin and the thiol side chain of a cysteine residue since neither prior treatment of cells with iodoacetamide nor curcumin with cysteine alters curcumin's inhibitory effects. Curcumin is a mixed inhibitor reducing the Vmax of 2DG transport by about half with little effect on the Km. The inhibitory effects of curcumin are not additive to the effects of cytochalasin B and 75 μM curcumin actually reduces specific cytochalasin B binding by 80%. Taken together, the data suggest that curcumin binds directly to GLUT1 at a site that overlaps with the cytochalasin B binding site and thereby inhibits glucose transport. A direct inhibition of GLUT proteins in intestinal epithelial cells would likely reduce absorption of dietary glucose and contribute to a hypoglycemic effect of curcumin. Also, inhibition of GLUT1 activity might compromise cancer cells that overexpress GLUT1 and be another possible mechanism for the documented anticancer effects of curcumin. PMID:27039889

  10. Thermodynamics of Irreversible Processes. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Levin, Michael; Gallucci, V. F.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module describes the application of irreversible thermodynamics to biology. It begins with…

  11. Speech perception as an active cognitive process

    PubMed Central

    Heald, Shannon L. M.; Nusbaum, Howard C.

    2014-01-01

    One view of speech perception is that acoustic signals are transformed into representations for pattern matching to determine linguistic structure. This process can be taken as a statistical pattern-matching problem, assuming realtively stable linguistic categories are characterized by neural representations related to auditory properties of speech that can be compared to speech input. This kind of pattern matching can be termed a passive process which implies rigidity of processing with few demands on cognitive processing. An alternative view is that speech recognition, even in early stages, is an active process in which speech analysis is attentionally guided. Note that this does not mean consciously guided but that information-contingent changes in early auditory encoding can occur as a function of context and experience. Active processing assumes that attention, plasticity, and listening goals are important in considering how listeners cope with adverse circumstances that impair hearing by masking noise in the environment or hearing loss. Although theories of speech perception have begun to incorporate some active processing, they seldom treat early speech encoding as plastic and attentionally guided. Recent research has suggested that speech perception is the product of both feedforward and feedback interactions between a number of brain regions that include descending projections perhaps as far downstream as the cochlea. It is important to understand how the ambiguity of the speech signal and constraints of context dynamically determine cognitive resources recruited during perception including focused attention, learning, and working memory. Theories of speech perception need to go beyond the current corticocentric approach in order to account for the intrinsic dynamics of the auditory encoding of speech. In doing so, this may provide new insights into ways in which hearing disorders and loss may be treated either through augementation or therapy. PMID

  12. The Vesicle Protein SAM-4 Regulates the Processivity of Synaptic Vesicle Transport

    PubMed Central

    Zheng, Qun; Ahlawat, Shikha; Schaefer, Anneliese; Mahoney, Tim; Koushika, Sandhya P.; Nonet, Michael L.

    2014-01-01

    Axonal transport of synaptic vesicles (SVs) is a KIF1A/UNC-104 mediated process critical for synapse development and maintenance yet little is known of how SV transport is regulated. Using C. elegans as an in vivo model, we identified SAM-4 as a novel conserved vesicular component regulating SV transport. Processivity, but not velocity, of SV transport was reduced in sam-4 mutants. sam-4 displayed strong genetic interactions with mutations in the cargo binding but not the motor domain of unc-104. Gain-of-function mutations in the unc-104 motor domain, identified in this study, suppress the sam-4 defects by increasing processivity of the SV transport. Genetic analyses suggest that SAM-4, SYD-2/liprin-α and the KIF1A/UNC-104 motor function in the same pathway to regulate SV transport. Our data support a model in which the SV protein SAM-4 regulates the processivity of SV transport. PMID:25329901

  13. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Yves; Satorius, Michael; Busch, Andreas; Krooß, Bernhard

    2013-04-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a sub bituminous A coal from the Surat Basin, Queensland Australia. From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg corrected permeability shows a gas type dependence. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa we observe with increasing mean pressure at lower confining pressure an increase in permeability which we attribute to a cleat aperture widening. The cleat volume compressibility (cf) also shows a dependence on the mean pore pressure. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. This permeability hysteresis is in accordance with results reported by Harpalani and McPherson (1985). The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals

  14. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Y.; Sartorius, M.; Busch, A.; Cumming, D.; Krooss, B. M.

    2012-04-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a sub bituminous A coal from the Surat Basin, Queensland Australia. From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg corrected permeability shows a gas type dependence. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa we observe with increasing mean pressure at lower confining pressure an increase in permeability which we attribute to a cleat aperture widening. The cleat volume compressibility (cf) also shows a dependence on the mean pore pressure. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. This permeability hysteresis is in accordance with results reported by Harpalani and McPherson (1985). The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals

  15. Artemisinin Inhibits Chloroplast Electron Transport Activity: Mode of Action

    PubMed Central

    Bharati, Adyasha; Kar, Monaranjan; Sabat, Surendra Chandra

    2012-01-01

    Artemisinin, a secondary metabolite produced in Artemisia plant species, besides having antimalarial properties is also phytotoxic. Although, the phytotoxic activity of the compound has been long recognized, no information is available on the mechanism of action of the compound on photosynthetic activity of the plant. In this report, we have evaluated the effect of artemisinin on photoelectron transport activity of chloroplast thylakoid membrane. The inhibitory effect of the compound, under in vitro condition, was pronounced in loosely and fully coupled thylakoids; being strong in the former. The extent of inhibition was drastically reduced in the presence of uncouplers like ammonium chloride or gramicidin; a characteristic feature described for energy transfer inhibitors. The compound, on the other hand, when applied to plants (in vivo), behaved as a potent inhibitor of photosynthetic electron transport. The major site of its action was identified to be the QB; the secondary quinone moiety of photosystemII complex. Analysis of photoreduction kinetics of para-benzoquinone and duroquinone suggest that the inhibition leads to formation of low pool of plastoquinol, which becomes limiting for electron flow through photosystemI. Further it was ascertained that the in vivo inhibitory effect appeared as a consequence of the formation of an unidentified artemisinin-metabolite rather than by the interaction of the compound per se. The putative metabolite of artemisinin is highly reactive in instituting the inhibition of photosynthetic electron flow eventually reducing the plant growth. PMID:22719995

  16. Dopamine Transporter Activity Is Modulated by α-Synuclein.

    PubMed

    Butler, Brittany; Saha, Kaustuv; Rana, Tanu; Becker, Jonas P; Sambo, Danielle; Davari, Paran; Goodwin, J Shawn; Khoshbouei, Habibeh

    2015-12-01

    The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases have all been associated with altered DAT activity. The membrane localization and the activity of DAT are regulated by a number of intracellular proteins. α-Synuclein, a protein partner of DAT, is implicated in neurodegenerative disease and drug addiction. Little is known about the regulatory mechanisms of the interaction between DAT and α-synuclein, the cellular location of this interaction, and the functional consequences of this interaction on the basal, amphetamine-induced DAT-mediated dopamine efflux, and membrane microdomain distribution of the transporter. Here, we found that the majority of DAT·α-synuclein protein complexes are found at the plasma membrane of dopaminergic neurons or mammalian cells and that the amphetamine-mediated increase in DAT activity enhances the association of these proteins at the plasma membrane. Further examination of the interaction of DAT and α-synuclein revealed a transient interaction between these two proteins at the plasma membrane. Additionally, we found DAT-induced membrane depolarization enhances plasma membrane localization of α-synuclein, which in turn increases dopamine efflux and enhances DAT localization in cholesterol-rich membrane microdomains. PMID:26442590

  17. Uterine activity, sperm transport, and the role of boar stimuli around insemination in sows.

    PubMed

    Langendijk, P; Soede, N M; Kemp, B

    2005-01-15

    This paper describes changes in spontaneous myometrial activity around estrus, factors that affect myometrial activity, and the possible role of uterine contractions in the process of (artificial) insemination, sperm transport and fertilization. Myometrial activity in the sow increases during estrus. The activity is myogenic in origin, but several factors have been shown to affect myometrial activity. Natural mating stimulates uterine contractions through several mechanisms. The presence of a boar, rather than the act of mating, induces central oxytocin release in the sow and thus increases uterine activity. Estrogens in the ejaculate of a boar can trigger prostaglandin release by the endometrium and thus increase uterine activity. Tactile stimulation of the genital tract (cervix) or tactile stimulation of the back and flanks of the sow during artificial insemination does not cause a release of oxytocin. There is hardly any evidence for the effects of these latter stimuli on uterine activity, and if they are present at all, the effects are very small. Evidence for the effects of synthetic boar odor on oxytocin release and/or uterine activity is inconsistent. The mere presence of a boar during insemination, in contrast, clearly stimulates uterine activity through the release of oxytocin. Hormonal stimulation (intrauterine) of uterine activity with estrogens, prostaglandins, or oxytocins before, during or after insemination generally improves fertilization rate, especially in situations with reduced fertility. Therefore, uterine contractions are believed to play an important role in the transport of sperm cells to the oviducts after insemination. Whether uterine contractions are absolutely necessary for sperm transport through the uterine horns, however, is not clear. Intensive stimulation of uterine contractions using hormones can also reduce the fertilization rate, probably by increasing the reflux of sperm cells during insemination. In this respect, the presence

  18. Controlling Contagion Processes in Activity Driven Networks

    NASA Astrophysics Data System (ADS)

    Liu, Suyu; Perra, Nicola; Karsai, Márton; Vespignani, Alessandro

    2014-03-01

    The vast majority of strategies aimed at controlling contagion processes on networks consider the connectivity pattern of the system either quenched or annealed. However, in the real world, many networks are highly dynamical and evolve, in time, concurrently with the contagion process. Here, we derive an analytical framework for the study of control strategies specifically devised for a class of time-varying networks, namely activity-driven networks. We develop a block variable mean-field approach that allows the derivation of the equations describing the coevolution of the contagion process and the network dynamic. We derive the critical immunization threshold and assess the effectiveness of three different control strategies. Finally, we validate the theoretical picture by simulating numerically the spreading process and control strategies in both synthetic networks and a large-scale, real-world, mobile telephone call data set.

  19. Active patterning and asymmetric transport in a model actomyosin network

    SciTech Connect

    Wang, Shenshen; Wolynes, Peter G.

    2013-12-21

    Cytoskeletal networks, which are essentially motor-filament assemblies, play a major role in many developmental processes involving structural remodeling and shape changes. These are achieved by nonequilibrium self-organization processes that generate functional patterns and drive intracellular transport. We construct a minimal physical model that incorporates the coupling between nonlinear elastic responses of individual filaments and force-dependent motor action. By performing stochastic simulations we show that the interplay of motor processes, described as driving anti-correlated motion of the network vertices, and the network connectivity, which determines the percolation character of the structure, can indeed capture the dynamical and structural cooperativity which gives rise to diverse patterns observed experimentally. The buckling instability of individual filaments is found to play a key role in localizing collapse events due to local force imbalance. Motor-driven buckling-induced node aggregation provides a dynamic mechanism that stabilizes the two-dimensional patterns below the apparent static percolation limit. Coordinated motor action is also shown to suppress random thermal noise on large time scales, the two-dimensional configuration that the system starts with thus remaining planar during the structural development. By carrying out similar simulations on a three-dimensional anchored network, we find that the myosin-driven isotropic contraction of a well-connected actin network, when combined with mechanical anchoring that confers directionality to the collective motion, may represent a novel mechanism of intracellular transport, as revealed by chromosome translocation in the starfish oocyte.

  20. Active patterning and asymmetric transport in a model actomyosin network

    NASA Astrophysics Data System (ADS)

    Wang, Shenshen; Wolynes, Peter G.

    2013-12-01

    Cytoskeletal networks, which are essentially motor-filament assemblies, play a major role in many developmental processes involving structural remodeling and shape changes. These are achieved by nonequilibrium self-organization processes that generate functional patterns and drive intracellular transport. We construct a minimal physical model that incorporates the coupling between nonlinear elastic responses of individual filaments and force-dependent motor action. By performing stochastic simulations we show that the interplay of motor processes, described as driving anti-correlated motion of the network vertices, and the network connectivity, which determines the percolation character of the structure, can indeed capture the dynamical and structural cooperativity which gives rise to diverse patterns observed experimentally. The buckling instability of individual filaments is found to play a key role in localizing collapse events due to local force imbalance. Motor-driven buckling-induced node aggregation provides a dynamic mechanism that stabilizes the two-dimensional patterns below the apparent static percolation limit. Coordinated motor action is also shown to suppress random thermal noise on large time scales, the two-dimensional configuration that the system starts with thus remaining planar during the structural development. By carrying out similar simulations on a three-dimensional anchored network, we find that the myosin-driven isotropic contraction of a well-connected actin network, when combined with mechanical anchoring that confers directionality to the collective motion, may represent a novel mechanism of intracellular transport, as revealed by chromosome translocation in the starfish oocyte.

  1. Interfacial phenomena and microscale transport processes in evaporating ultrathin menisci

    NASA Astrophysics Data System (ADS)

    Panchamgam, Sashidhar S.

    The study of interfacial phenomena in the three-phase contact line region, where a liquid-vapor interface intersects a solid surface, is of importance to many equilibrium and non-equilibrium processes. However, lack of experimental data on microscale transport processes controlled by interfacial phenomena has restricted progress. This thesis includes a high resolution image analyzing technique, based on reflectivity measurements, that accurately measures the thickness, contact angle and curvature profiles of ultrathin films, drops and curved menisci. In particular, the technique was used to emphasize measurements for thicknesses, delta < 100 nm, while studying delta < 2.5 mum. Using the "reflectivity technique", we studied fluid flow and heat transfer in a wickless, miniature heat pipe, a device which will be a very effective passive heat exchanger in a microgravity environment. The heat pipe is based on the Vertical Constrained Vapor Bubble (VCVB) concept. The broad objective was to increase the efficiency of the miniature heat pipe by enhancing the liquid flow towards the hotter region. This was achieved by understanding and manipulating the wetting and spreading characteristics of the liquid on the solid surface. By using a binary mixture (98% pentane and 2% octane by volume) instead of either pure pentane or octane, we were able to achieve a significant increase in the microscale phase change heat transfer. The experimental work was supported by numerical studies to understand the physics of the system at microscopic scale. In addition, using the reflectivity technique, we enhanced our understanding of interfacial phenomena in the contact line region. Experiments included flow instabilities in HFE-7000 meniscus on quartz (System S1), the spreading of a pentane (System S2 and S3), octane (System S4) and binary mixture menisci (System S5) during evaporation. The main objectives of the work are to present a new experimental technique, new observations, new data

  2. The bacterial flagellar protein export apparatus processively transports flagellar proteins even with extremely infrequent ATP hydrolysis

    PubMed Central

    Minamino, Tohru; Morimoto, Yusuke V.; Kinoshita, Miki; Aldridge, Phillip D.; Namba, Keiichi

    2014-01-01

    For self-assembly of the bacterial flagellum, a specific protein export apparatus utilizes ATP and proton motive force (PMF) as the energy source to transport component proteins to the distal growing end. The export apparatus consists of a transmembrane PMF-driven export gate and a cytoplasmic ATPase complex composed of FliH, FliI and FliJ. The FliI6FliJ complex is structurally similar to the α3β3γ complex of FOF1-ATPase. FliJ allows the gate to efficiently utilize PMF to drive flagellar protein export but it remains unknown how. Here, we report the role of ATP hydrolysis by the FliI6FliJ complex. The export apparatus processively transported flagellar proteins to grow flagella even with extremely infrequent or no ATP hydrolysis by FliI mutation (E211D and E211Q, respectively). This indicates that the rate of ATP hydrolysis is not at all coupled with the export rate. Deletion of FliI residues 401 to 410 resulted in no flagellar formation although this FliI deletion mutant retained 40% of the ATPase activity, suggesting uncoupling between ATP hydrolysis and activation of the gate. We propose that infrequent ATP hydrolysis by the FliI6FliJ ring is sufficient for gate activation, allowing processive translocation of export substrates for efficient flagellar assembly. PMID:25531309

  3. CFD Model of Water Droplet Transport for ISS Hygiene Activity

    NASA Technical Reports Server (NTRS)

    Son, Chang H.

    2011-01-01

    The goal of the study is to assess the impacts of free water propagation in the Waste and Hygiene Compartment (WHC). Free water can be generated inside the WHC in small quantities due to crew hygiene activity. To mitigate potential impact of free water in Node 3 cabin the WHC doorway is enclosed by a waterproof bump-out, Kabin, with openings at the top and bottom. At the overhead side of the rack, there is a screen that prevents large drops of water from exiting. However, as the avionics fan in the WHC causes airflow toward the deck side of the rack, small quantities of free water may exit at the bottom of the Kabin. A Computational Fluid Dynamics (CFD) analysis of Node 3 cabin airflow made possible to identify the paths of water transport. The Node 3 airflow was computed for several ventilation scenarios. To simulate the droplet transport the Lagrangian discrete phase approach was used. Various initial droplet distributions were considered in the study. The droplet diameter was varied in the range of 2-20 mm. The results of the computations showed that most of the drops fall to the rack surface not far from the WHC curtain. The probability of the droplet transport to the adjacent rack surface with electronic equipment was predicted.

  4. Adult Active Transport in the Netherlands: An Analysis of Its Contribution to Physical Activity Requirements

    PubMed Central

    Fishman, Elliot; Böcker, Lars; Helbich, Marco

    2015-01-01

    Introduction Modern, urban lifestyles have engineered physical activity out of everyday life and this presents a major threat to human health. The Netherlands is a world leader in active travel, particularly cycling, but little research has sought to quantify the cumulative amount of physical activity through everyday walking and cycling. Methods Using data collected as part of the Dutch National Travel Survey (2010 – 2012), this paper determines the degree to which Dutch walking and cycling contributes to meeting minimum level of physical activity of 150 minutes of moderate intensity aerobic activity throughout the week. The sample includes 74,465 individuals who recorded at least some travel on the day surveyed. As physical activity benefits are cumulative, all walking and cycling trips are analysed, including those to and from public transport. These trips are then converted into an established measure of physical activity intensity, known as metabolic equivalents of tasks. Multivariate Tobit regression models were performed on a range of socio-demographic, transport resources, urban form and meteorological characteristics. Results The results reveal that Dutch men and women participate in 24 and 28 minutes of daily physical activity through walking and cycling, which is 41% and 55% more than the minimum recommended level. It should be noted however that some 57% of the entire sample failed to record any walking or cycling, and an investigation of this particular group serves as an important topic of future research. Active transport was positively related with age, income, bicycle ownership, urban density and air temperature. Car ownership had a strong negative relationship with physically active travel. Conclusion The results of this analysis demonstrate the significance of active transport to counter the emerging issue of sedentary lifestyle disease. The Dutch experience provides other countries with a highly relevant case study in the creation of

  5. 23 CFR 450.306 - Scope of the metropolitan transportation planning process.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Scope of the metropolitan transportation planning process. 450.306 Section 450.306 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH PLANNING ASSISTANCE AND STANDARDS Metropolitan Transportation Planning and Programming § 450.306 Scope of the...

  6. Process for preparing active oxide powders

    DOEpatents

    Berard, Michael F.; Hunter, Jr., Orville; Shiers, Loren E.; Dole, Stephen L.; Scheidecker, Ralph W.

    1979-02-20

    An improved process for preparing active oxide powders in which cation hydroxide gels, prepared in the conventional manner are chemically dried by alternately washing the gels with a liquid organic compound having polar characteristics and a liquid organic compound having nonpolar characteristics until the mechanical water is removed from the gel. The water-free cation hydroxide is then contacted with a final liquid organic wash to remove the previous organic wash and speed drying. The dried hydroxide treated in the conventional manner will form a highly sinterable active oxide powder.

  7. PET measurement of glucose membrane transport using labeled analogs: Distinction of transport from metabolic processes

    SciTech Connect

    Holden, J.E.; Koeppe, R.A.; Gatley, S.J.

    1984-01-01

    Carrier mediated glucose transport rates across brain capillary and myocardial cell membranes are many times higher than those expected for simple diffusion, and transport regulation can be an important determinant of tissue metabolic status. The authors have investigated the use of glucose analogs and dynamic positron tomography for the non-invasive measurement of unidirectional membrane transport rates. If analog extraction is sufficiently low, transport rates can be inferred directly from fitted kinetic rate constants. Fitting calculations were seen to be sensitive to the difficult to measure rapid components of the arterial input curves, to contributions from blood-borne label in the early data points, and to interference from other chemical forms in cases of significant phosphorylation. This last uncertainty was studied using serial scans of normal brain after venous injection of the well-transported but poorly phosphorylated analog 3-deoxy-3-fluoroglucose. Transport rate constants derived from 4-parameter fits of three hours of data were compared to those derived from 2-parameter fits of the first 12-20 minutes of data. Errors due to trapped label were absorbed primarily into the apparent distribution volume, allowing accurate estimation of transport rate constants from a brief data acquisition period. The study of the distinction of transport from phosphorylation also bears on the important question of the significance of the individual rate constants in the four-parameter fitting of brief dynamic scan sequences in studies of metabolic rate using 2-deoxy-2-fluoroglucose.

  8. Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

    SciTech Connect

    Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

  9. Tubular Unimolecular Transmembrane Channels: Construction Strategy and Transport Activities.

    PubMed

    Si, Wen; Xin, Pengyang; Li, Zhan-Ting; Hou, Jun-Li

    2015-06-16

    Lipid bilayer membranes separate living cells from their environment. Membrane proteins are responsible for the processing of ion and molecular inputs and exports, sensing stimuli and signals across the bilayers, which may operate in a channel or carrier mechanism. Inspired by these wide-ranging functions of membrane proteins, chemists have made great efforts in constructing synthetic mimics in order to understand the transport mechanisms, create materials for separation, and develop therapeutic agents. Since the report of an alkylated cyclodextrin for transporting Cu(2+) and Co(2+) by Tabushi and co-workers in 1982, chemists have constructed a variety of artificial transmembrane channels by making use of either the multimolecular self-assembly or unimolecular strategy. In the context of the design of unimolecular channels, important advances have been made, including, among others, the tethering of natural gramicidin A or alamethicin and the modification of various macrocycles such as crown ethers, cyclodextrins, calixarenes, and cucurbiturils. Many of these unimolecular channels exhibit high transport ability for metal ions, particularly K(+) and Na(+). Concerning the development of artificial channels based on macrocyclic frameworks, one straightforward and efficient approach is to introduce discrete chains to reinforce their capability to insert into bilayers. Currently, this approach has found the widest applications in the systems of crown ethers and calixarenes. We envisioned that for macrocycle-based unimolecular channels, control of the arrangement of the appended chains in the upward and/or downward direction would favor the insertion of the molecular systems into bilayers, while the introduction of additional interactions among the chains would further stabilize a tubular conformation. Both factors should be helpful for the formation of new efficient channels. In this Account, we discuss our efforts in designing new unimolecular artificial channels from

  10. Kinetic theory of transport processes in partially ionized reactive plasma, I: General transport equations

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    In this paper we derive the set of general transport equations for multicomponent partially ionized reactive plasma in the presence of electric and magnetic fields taking into account the internal degrees of freedom and electronic excitation of plasma particles. Our starting point is a generalized Boltzmann equation with the collision integral in the Wang-Chang and Uhlenbeck form and a reactive collision integral. We obtain a set of conservation equations for such plasma and employ a linearized variant of Grad's moment method to derive the system of moment (or transport) equations for the plasma species nonequilibrium parameters. Full and reduced transport equations, resulting from the linearized system of moment equations, are presented, which can be used to obtain transport relations and expressions for transport coefficients of electrons and heavy plasma particles (molecules, atoms and ions) in partially ionized reactive plasma.

  11. All-solution-processed inverted organic solar cell with a stacked hole-transporting layer

    NASA Astrophysics Data System (ADS)

    Lin, Wen-Kai; Su, Shui-Hsiang; Liu, Che-Chun; Yokoyama, Meiso

    2014-11-01

    In this study, inverted organic solar cells (IOSCs) have been fabricated and characterized. A sol-gel zinc oxide (ZnO) film is used as a hole-blocking layer (HBL). Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and copper phthalocyanine (CuPc) are used as a hole-transporting layer (HTL). The HBL, active layer, and HTL films are fabricated by spin-coating technique. The anode is fabricated from Ag nanoparticles by drop titration using a Pasteur burette. Experimental results show that the PEDOT:PSS/CuPc stacked HTL provides a stepwise hole-transporting energy diagram configuration, which subsequently increases the charge carrier transporting capability and extracts holes from the active layer to the anode. The characteristics of the IOSCs were optimized and exhibited an open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) of 0.53 V, 6.13 mA/cm2, 37.53%, and 1.24%, respectively, under simulated AM1.5G illumination of 100 mW/cm2. Hence, a solution process is feasible for fabricating low-cost and large-area solar energy devices.

  12. Na(+)-independent multispecific anion transporter mediates active transport of pravastatin into rat liver.

    PubMed

    Yamazaki, M; Suzuki, H; Hanano, M; Tokui, T; Komai, T; Sugiyama, Y

    1993-01-01

    To examine whether the relatively selective inhibition of hepatic cholesterol synthesis by the hydrophilic 3-hydroxyl-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor pravastatin in vivo may be due to the existence of a specific uptake mechanism in the liver, the uptake by isolated rat hepatocytes was investigated. The uptake was composed of a saturable component [Michaelis constant (Km) 29 microM, maximal uptake rate 546 pmol.min-1.mg-1] and nonspecific diffusion (nonspecific uptake clearance 1.6 microliters.min-1.mg-1), inhibited by hypothermia, metabolic inhibitors, sulfhydryl-modifying reagents, and inhibitor of anion exchanger, whereas replacement of Na+ by choline+ or Cl- by gluconate- did not alter the uptake. Competitive inhibition was observed by a more highly lipophilic HMG-CoA reductase inhibitor simvastatin (open acid form), dibromosulfophthalein, cholate, and taurocholate. Pravastatin inhibited Na(+)-independent taurocholate uptake with an inhibition constant comparable with the Km value of pravastatin itself. Furthermore, the hepatic permeability clearance in vivo obtained with intact rats was comparable with that in vitro, indicating that the carrier-mediated active transport system we demonstrated in vitro is responsible for the hepatic uptake in vivo. These findings demonstrated that the hepatic uptake of pravastatin occurs via a carrier-mediated active transport mechanism utilizing the so-called multispecific anion transporter, which is common with the Na(+)-independent bile acid uptake system, and that this is one of the mechanisms for its selective inhibition of hepatic cholesterol synthesis in vivo. PMID:8430803

  13. Active voltammetric microsensors with neural signal processing.

    SciTech Connect

    Vogt, M. C.

    1998-12-11

    Many industrial and environmental processes, including bioremediation, would benefit from the feedback and control information provided by a local multi-analyte chemical sensor. For most processes, such a sensor would need to be rugged enough to be placed in situ for long-term remote monitoring, and inexpensive enough to be fielded in useful numbers. The multi-analyte capability is difficult to obtain from common passive sensors, but can be provided by an active device that produces a spectrum-type response. Such new active gas microsensor technology has been developed at Argonne National Laboratory. The technology couples an electrocatalytic ceramic-metallic (cermet) microsensor with a voltammetric measurement technique and advanced neural signal processing. It has been demonstrated to be flexible, rugged, and very economical to produce and deploy. Both narrow interest detectors and wide spectrum instruments have been developed around this technology. Much of this technology's strength lies in the active measurement technique employed. The technique involves applying voltammetry to a miniature electrocatalytic cell to produce unique chemical ''signatures'' from the analytes. These signatures are processed with neural pattern recognition algorithms to identify and quantify the components in the analyte. The neural signal processing allows for innovative sampling and analysis strategies to be employed with the microsensor. In most situations, the whole response signature from the voltammogram can be used to identify, classify, and quantify an analyte, without dissecting it into component parts. This allows an instrument to be calibrated once for a specific gas or mixture of gases by simple exposure to a multi-component standard rather than by a series of individual gases. The sampled unknown analytes can vary in composition or in concentration, the calibration, sensing, and processing methods of these active voltammetric microsensors can detect, recognize, and

  14. Pentagalloylglucose Blocks the Nuclear Transport and the Process of Nucleocapsid Egress to Inhibit HSV-1 Infection.

    PubMed

    Jin, Fujun; Ma, Kaiqi; Chen, Maoyun; Zou, Muping; Wu, Yanting; Li, Feng; Wang, Yifei

    2016-03-23

    Herpes simplex virus type 1 (HSV-1), a widespread virus, causes a variety of human viral diseases worldwide. The serious threat of drug-resistance highlights the extreme urgency to develop novel antiviral drugs with different mechanisms of action. Pentagalloylglucose (PGG) is a natural polyphenolic compound with significant anti-HSV activity; however, the mechanisms underlying its antiviral activity need to be defined by further studies. In this study, we found that PGG treatment delays the nuclear transport process of HSV-1 particles by inhibiting the upregulation of dynein (a cellular major motor protein) induced by HSV-1 infection. Furthermore, PGG treatment affects the nucleocapsid egress of HSV-1 by inhibiting the expression and disrupting the cellular localization of pEGFP-UL31 and pEGFP-UL34, which are indispensable for HSV-1 nucleocapsid egress from the nucleus. However, the over-expression of pEGFP-UL31 and pEGFP-UL34 could decrease the antiviral effect of PGG. In this study, for the first time, the antiviral activity of PGG against acyclovir-resistant virus was demonstrated in vitro, and the possible mechanisms of its anti-HSV activities were identified based on the inhibition of nuclear transport and nucleocapsid egress in HSV-1. It was further confirmed that PGG could be a promising candidate for HSV therapy, especially for drug-resistant strains. PMID:26166506

  15. Active migration and passive transport of malaria parasites.

    PubMed

    Douglas, Ross G; Amino, Rogerio; Sinnis, Photini; Frischknecht, Freddy

    2015-08-01

    Malaria parasites undergo a complex life cycle between their hosts and vectors. During this cycle the parasites invade different types of cells, migrate across barriers, and transfer from one host to another. Recent literature hints at a misunderstanding of the difference between active, parasite-driven migration and passive, circulation-driven movement of the parasite or parasite-infected cells in the various bodily fluids of mosquito and mammalian hosts. Because both active migration and passive transport could be targeted in different ways to interfere with the parasite, a distinction between the two ways the parasite uses to get from one location to another is essential. We discuss the two types of motion needed for parasite dissemination and elaborate on how they could be targeted by future vaccines or drugs. PMID:26001482

  16. Directed transport of active particles over asymmetric energy barriers.

    PubMed

    Koumakis, N; Maggi, C; Di Leonardo, R

    2014-08-21

    We theoretically and numerically investigate the transport of active colloids to target regions, delimited by asymmetric energy barriers. We show that it is possible to introduce a generalized effective temperature that is related to the local variance of particle velocities. The stationary probability distributions can be derived from a simple diffusion equation in the presence of an inhomogeneous effective temperature resulting from the action of external force fields. In particular, transition rates over asymmetric energy barriers can be unbalanced by having different effective temperatures over the two slopes of the barrier. By varying the type of active noise, we find that equal values of diffusivity and persistence time may produce strongly varied effective temperatures and thus stationary distributions. PMID:24978345

  17. Modeling preferential water flow and solute transport in unsaturated soil using the active region model

    SciTech Connect

    Sheng, F.; Wang, K.; Zhang, R.; Liu, H.H.

    2009-03-15

    Preferential flow and solute transport are common processes in the unsaturated soil, in which distributions of soil water content and solute concentrations are often characterized as fractal patterns. An active region model (ARM) was recently proposed to describe the preferential flow and transport patterns. In this study, ARM governing equations were derived to model the preferential soil water flow and solute transport processes. To evaluate the ARM equations, dye infiltration experiments were conducted, in which distributions of soil water content and Cl{sup -} concentration were measured. Predicted results using the ARM and the mobile-immobile region model (MIM) were compared with the measured distributions of soil water content and Cl{sup -} concentration. Although both the ARM and the MIM are two-region models, they are fundamental different in terms of treatments of the flow region. The models were evaluated based on the modeling efficiency (ME). The MIM provided relatively poor prediction results of the preferential flow and transport with negative ME values or positive ME values less than 0.4. On the contrary, predicted distributions of soil water content and Cl- concentration using the ARM agreed reasonably well with the experimental data with ME values higher than 0.8. The results indicated that the ARM successfully captured the macroscopic behavior of preferential flow and solute transport in the unsaturated soil.

  18. A fully resolved fluid-structure-muscle-activation model for esophageal transport

    NASA Astrophysics Data System (ADS)

    Kou, Wenjun; Bhalla, Amneet P. S.; Griffith, Boyce E.; Johnson, Mark; Patankar, Neelesh A.

    2013-11-01

    Esophageal transport is a mechanical and physiological process that transfers the ingested food bolus from the pharynx to the stomach through a multi-layered esophageal tube. The process involves interactions between the bolus, esophageal wall composed of mucosal, circular muscle (CM) and longitudinal muscle (LM) layers, and neurally coordinated muscle activation including CM contraction and LM shortening. In this work, we present a 3D fully-resolved model of esophageal transport based on the immersed boundary method. The model describes the bolus as a Newtonian fluid, the esophageal wall as a multi-layered elastic tube represented by springs and beams, and the muscle activation as a traveling wave of sequential actuation/relaxation of muscle fibers, represented by springs with dynamic rest lengths. Results on intraluminal pressure profile and bolus shape will be shown, which are qualitatively consistent with experimental observations. Effects of activating CM contraction only, LM shortening only or both, for the bolus transport, are studied. A comparison among them can help to identify the role of each type of muscle activation. The support of grant R01 DK56033 and R01 DK079902 from NIH is gratefully acknowledged.

  19. Active Transport of Nanomaterials Using Motor Proteins -Final Report

    SciTech Connect

    Hess, Henry

    2005-09-01

    During the six months of funding we have focused first on the completion of the research begun at the University of Washington in the previous funding cycle. Specifically, we developed a method to polymerize oriented networks of microtubules on lithographically patterned surfaces (M.S. thesis Robert Doot). The properties of active transport have been studied detail, yielding insights into the dispersion mechanisms (Nitta et al.). The assembly of multifunctional structures with a microtubule core has been investigated (Ramachandran et al.). Isaac Luria (B.S. in physics, U. of Florida 2005) worked on the directed assembly of nanoscale, non-equilibrium structures as a summer intern. He is now a graduate student in my group at the University of Florida. T. Nitta and H. Hess: Dispersion in Active Transport by Kinesin-Powered Molecular Shuttles, Nano Letters, 5, 1337-1342 (2005) S. Ramachandran, K.-H. Ernst, G. D. Bachand, V. Vogel, H. Hess*: Selective Loading of Kinesin-Powered Molecular Shuttles with Protein Cargo and its Application to Biosensing, submitted to Small (2005)

  20. Socioeconomic and regional differences in active transportation in Brazil

    PubMed Central

    de Sá, Thiago Hérick; Pereira, Rafael Henrique Moraes; Duran, Ana Clara; Monteiro, Carlos Augusto

    2016-01-01

    ABSTRACT OBJECTIVE To present national estimates regarding walking or cycling for commuting in Brazil and in 10 metropolitan regions. METHODS By using data from the Health section of 2008’s Pesquisa Nacional por Amostra de Domicílio (Brazil’s National Household Sample Survey), we estimated how often employed people walk or cycle to work, disaggregating our results by sex, age range, education level, household monthly income per capita, urban or rural address, metropolitan regions, and macro-regions in Brazil. Furthermore, we estimated the distribution of this same frequency according to quintiles of household monthly income per capita in each metropolitan region of the country. RESULTS A third of the employed men and women walk or cycle from home to work in Brazil. For both sexes, this share decreases as income and education levels rise, and it is higher among younger individuals, especially among those living in rural areas and in the Northeast region of the country. Depending on the metropolitan region, the practice of active transportation is two to five times more frequent among low-income individuals than among high-income individuals. CONCLUSIONS Walking or cycling to work in Brazil is most frequent among low-income individuals and the ones living in less economically developed areas. Active transportation evaluation in Brazil provides important information for public health and urban mobility policy-making PMID:27355465

  1. Activation of consolidation processes of alumina ceramics

    NASA Astrophysics Data System (ADS)

    Matrenin, S. V.; Zenin, B. S.; Tayukin, R. V.

    2016-02-01

    The methods for activating sintering ceramics based on Al2O3 by mechanical activation in the planetary mill, by adding in the mixture of nanopowders (NP) Al, Al2O3, and submicron powder TiO2, and by applying the technology of spark plasma sintering (SPS) are developed. It has been shown that adding the nanopowder up to 20 wt. % Al2O3 in a coarse powder α-Al2O3 activates the sintering process resulting in increased density and hardness of the sintered alumina ceramics. Substantial effect of increasing density of alumina ceramics due to adding the submicron powder TiO2 in the compound of initial powder mixtures has been established.

  2. Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

    NASA Astrophysics Data System (ADS)

    Annewandter, R.

    2013-12-01

    The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced soil gas sampling during On-Site inspections. Gas transport has been widely studied with different numerical codes. However, gas transport of all radioxenons in the post-detonation regime and their possible fractionation is still neglected in the open literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radioxenons, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different diffusivities due to mass differences between the radioxenons. A previous study showed surface arrival time of a chemically inert gaseous tracer is affected by its diffusivity. They observed detectable amount for SF6 50 days after detonation and 375 days for He-3. They predict 50 and 80 days for Xe-133 and Ar-37 respectively. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations , fracture propagation in fractured, porous media, Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic

  3. Amphetamine activates calcium channels through dopamine transporter-mediated depolarization.

    PubMed

    Cameron, Krasnodara N; Solis, Ernesto; Ruchala, Iwona; De Felice, Louis J; Eltit, Jose M

    2015-11-01

    Amphetamine (AMPH) and its more potent enantiomer S(+)AMPH are psychostimulants used therapeutically to treat attention deficit hyperactivity disorder and have significant abuse liability. AMPH is a dopamine transporter (DAT) substrate that inhibits dopamine (DA) uptake and is implicated in DA release. Furthermore, AMPH activates ionic currents through DAT that modify cell excitability presumably by modulating voltage-gated channel activity. Indeed, several studies suggest that monoamine transporter-induced depolarization opens voltage-gated Ca(2+) channels (CaV), which would constitute an additional AMPH mechanism of action. In this study we co-express human DAT (hDAT) with Ca(2+) channels that have decreasing sensitivity to membrane depolarization (CaV1.3, CaV1.2 or CaV2.2). Although S(+)AMPH is more potent than DA in transport-competition assays and inward-current generation, at saturating concentrations both substrates indirectly activate voltage-gated L-type Ca(2+) channels (CaV1.3 and CaV1.2) but not the N-type Ca(2+) channel (CaV2.2). Furthermore, the potency to achieve hDAT-CaV electrical coupling is dominated by the substrate affinity on hDAT, with negligible influence of L-type channel voltage sensitivity. In contrast, the maximal coupling-strength (defined as Ca(2+) signal change per unit hDAT current) is influenced by CaV voltage sensitivity, which is greater in CaV1.3- than in CaV1.2-expressing cells. Moreover, relative to DA, S(+)AMPH showed greater coupling-strength at concentrations that induced relatively small hDAT-mediated currents. Therefore S(+)AMPH is not only more potent than DA at inducing hDAT-mediated L-type Ca(2+) channel currents but is a better depolarizing agent since it produces tighter electrical coupling between hDAT-mediated depolarization and L-type Ca(2+) channel activation. PMID:26162812

  4. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Congestion management process in transportation management areas. 450.320 Section 450.320 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF... Programming § 450.320 Congestion management process in transportation management areas. (a) The...

  5. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Congestion management process in transportation management areas. 450.320 Section 450.320 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF... Programming § 450.320 Congestion management process in transportation management areas. (a) The...

  6. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Congestion management process in transportation management areas. 450.320 Section 450.320 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF... Programming § 450.320 Congestion management process in transportation management areas. (a) The...

  7. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Congestion management process in transportation management areas. 450.320 Section 450.320 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF... Programming § 450.320 Congestion management process in transportation management areas. (a) The...

  8. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Congestion management process in transportation management areas. 450.320 Section 450.320 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF... Programming § 450.320 Congestion management process in transportation management areas. (a) The...

  9. Trailers transporting oranges to processing plants move Asian citrus psyllids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (citrus greening) is one of the most serious of citrus diseases. Movement of the disease occurs as a result of natural vector-borne infection and by movement of plant material. We demonstrate here that Diaphorina citri Kuwayama (vector of citrus greening pathogens) can be transported i...

  10. Complete solids retention activated sludge process.

    PubMed

    Amanatidou, E; Samiotis, G; Trikoilidou, E; Pekridis, G; Tsikritzis, L

    2016-01-01

    In a slaughterhouse's full-scale extended aeration activated sludge wastewater treatment plant (WWTP), operating under complete solids retention time, the evolution of mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) concentration, food to micro-organisms ratio (F/M) and substrate utilization rate (SUR) were studied for over a year. Biomass growth phases in correlation to sludge biological and morphological characteristics were studied. Three distinguished growth phases were observed during the 425 days of monitoring. The imposed operational conditions led the process to extended biomass starvation conditions, minimum F/M, minimum SUR and predator species growth. MLSS and MLVSS reached a stabilization phase (plateau phase) where almost zero sludge accumulation was observed. The concept of degradation of the considered non-biodegradable particulate compounds in influent and in biomass (cell debris) was also studied. Comparison of evolution of observed sludge yields (Yobs) in the WWTP with Yobs predictions by activated sludge models verified the degradation concept for the considered non-biodegradable compounds. Control of the sedimentation process was achieved, by predicting the solids loading rate critical point using state point analysis and stirred/unstirred settling velocity tests and by applying a high return activated sludge rate. The nitrogen gas related sedimentation problems were taken into consideration. PMID:27003077

  11. Modeling of an Active Tablet Coating Process.

    PubMed

    Toschkoff, Gregor; Just, Sarah; Knop, Klaus; Kleinebudde, Peter; Funke, Adrian; Djuric, Dejan; Scharrer, Georg; Khinast, Johannes G

    2015-12-01

    Tablet coating is a common unit operation in the pharmaceutical industry, during which a coating layer is applied to tablet cores. The coating uniformity of tablets in a batch is especially critical for active coating, that is, coating that contains an active pharmaceutical ingredient. In recent years, discrete element method (DEM) simulations became increasingly common for investigating tablet coating. In this work, DEM was applied to model an active coating process as closely as possible, using measured model parameters and non-spherical particles. We studied how operational conditions (rotation speed, fill level, number of nozzles, and spray rate) influence the coating uniformity. To this end, simulation runs were planned and interpreted according to a statistical design of (simulation) experiments. Our general goal was to achieve a deeper understanding of the process in terms of residence times and dimensionless scaling laws. With that regard, the results were interpreted in light of analytical models. The results were presented at various detail levels, ranging from an overview of all variations to in-depth considerations. It was determined that the biggest uniformity improvement in a realistic setting was achieved by increasing the number of spray nozzles, followed by increasing the rotation speed and decreasing the fill level. PMID:26344941

  12. Modeling field scale unsaturated flow and transport processes

    SciTech Connect

    Gelhar, L.W.; Celia, M.A.; McLaughlin, D.

    1994-08-01

    The scales of concern in subsurface transport of contaminants from low-level radioactive waste disposal facilities are in the range of 1 to 1,000 m. Natural geologic materials generally show very substantial spatial variability in hydraulic properties over this range of scales. Such heterogeneity can significantly influence the migration of contaminants. It is also envisioned that complex earth structures will be constructed to isolate the waste and minimize infiltration of water into the facility. The flow of water and gases through such facilities must also be a concern. A stochastic theory describing unsaturated flow and contamination transport in naturally heterogeneous soils has been enhanced by adopting a more realistic characterization of soil variability. The enhanced theory is used to predict field-scale effective properties and variances of tension and moisture content. Applications illustrate the important effects of small-scale heterogeneity on large-scale anisotropy and hysteresis and demonstrate the feasibility of simulating two-dimensional flow systems at time and space scales of interest in radioactive waste disposal investigations. Numerical algorithms for predicting field scale unsaturated flow and contaminant transport have been improved by requiring them to respect fundamental physical principles such as mass conservation. These algorithms are able to provide realistic simulations of systems with very dry initial conditions and high degrees of heterogeneity. Numerical simulation of the movement of water and air in unsaturated soils has demonstrated the importance of air pathways for contaminant transport. The stochastic flow and transport theory has been used to develop a systematic approach to performance assessment and site characterization. Hypothesis-testing techniques have been used to determine whether model predictions are consistent with observed data.

  13. Physical Activity Energy Expenditure in Dutch Adolescents: Contribution of Active Transport to School, Physical Education, and Leisure Time Activities

    ERIC Educational Resources Information Center

    Slingerland, Menno; Borghouts, Lars B.; Hesselink, Matthijs K. C.

    2012-01-01

    Background: Detailed knowledge about physical activity energy expenditure (PAEE) can guide the development of school interventions aimed at reducing overweight in adolescents. However, relevant components of PAEE have never been objectively quantified in this population. This study investigated the contribution of active transport to and from…

  14. Processing activities for STS-91 continue in OPF Bay 2

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Processing activities for STS-91 continue in KSC's Orbiter Processing Facility Bay 2. The payload bay of Space Shuttle Discovery is relatively empty as installation of the Get Away Special (GAS) canisters begins. Two GAS canisters can be seen in the center of the photograph. On the left is G-648, a Canadian Space Agency-sponsored study on manufactured organic thin film by the physical vapor transport method, and on the right is a can with hundreds of commemorative flags to be flown on the mission. STS-91 is scheduled to launch aboard the Space Shuttle Discovery for the ninth and final docking with the Russian Space Station Mir from KSC's Launch Pad 39A on June 2 with a launch window opening around 6:04 p.m. EDT.

  15. KIF5B transports BNIP-2 to regulate p38 mitogen-activated protein kinase activation and myoblast differentiation

    PubMed Central

    Yi, Peng; Chew, Li Li; Zhang, Ziwang; Ren, Hao; Wang, Feiya; Cong, Xiaoxia; Zheng, Liling; Luo, Yan; Ouyang, Hongwei; Low, Boon Chuan; Zhou, Yi Ting

    2015-01-01

    The Cdo-p38MAPK (p38 mitogen-activated protein kinase) signaling pathway plays important roles in regulating skeletal myogenesis. During myogenic differentiation, the cell surface receptor Cdo bridges scaffold proteins BNIP-2 and JLP and activates p38MAPK, but the spatial-temporal regulation of this process is largely unknown. We here report that KIF5B, the heavy chain of kinesin-1 motor, is a novel interacting partner of BNIP-2. Coimmunoprecipitation and far-Western study revealed that BNIP-2 directly interacted with the motor and tail domains of KIF5B via its BCH domain. By using a range of organelle markers and live microscopy, we determined the endosomal localization of BNIP-2 and revealed the microtubule-dependent anterograde transport of BNIP-2 in C2C12 cells. The anterograde transport of BNIP-2 was disrupted by a dominant-negative mutant of KIF5B. In addition, knockdown of KIF5B causes aberrant aggregation of BNIP-2, confirming that KIF5B is critical for the anterograde transport of BNIP-2 in cells. Gain- and loss-of-function experiments further showed that KIF5B modulates p38MAPK activity and in turn promotes myogenic differentiation. Of importance, the KIF5B-dependent anterograde transport of BNIP-2 is critical for its promyogenic effects. Our data reveal a novel role of KIF5B in the spatial regulation of Cdo–BNIP-2–p38MAPK signaling and disclose a previously unappreciated linkage between the intracellular transporting system and myogenesis regulation. PMID:25378581

  16. Fatty acid transport and activation and the expression patterns of genes involved in fatty acid trafficking.

    PubMed

    Sandoval, Angel; Fraisl, Peter; Arias-Barrau, Elsa; Dirusso, Concetta C; Singer, Diane; Sealls, Whitney; Black, Paul N

    2008-09-15

    These studies defined the expression patterns of genes involved in fatty acid transport, activation and trafficking using quantitative PCR (qPCR) and established the kinetic constants of fatty acid transport in an effort to define whether vectorial acylation represents a common mechanism in different cell types (3T3-L1 fibroblasts and adipocytes, Caco-2 and HepG2 cells and three endothelial cell lines (b-END3, HAEC, and HMEC)). As expected, fatty acid transport protein (FATP)1 and long-chain acyl CoA synthetase (Acsl)1 were the predominant isoforms expressed in adipocytes consistent with their roles in the transport and activation of exogenous fatty acids destined for storage in the form of triglycerides. In cells involved in fatty acid processing including Caco-2 (intestinal-like) and HepG2 (liver-like), FATP2 was the predominant isoform. The patterns of Acsl expression were distinct between these two cell types with Acsl3 and Acsl5 being predominant in Caco-2 cells and Acsl4 in HepG2 cells. In the endothelial lines, FATP1 and FATP4 were the most highly expressed isoforms; the expression patterns for the different Acsl isoforms were highly variable between the different endothelial cell lines. The transport of the fluorescent long-chain fatty acid C(1)-BODIPY-C(12) in 3T3-L1 fibroblasts and 3T3-L1 adipocytes followed typical Michaelis-Menten kinetics; the apparent efficiency (k(cat)/K(T)) of this process increases over 2-fold (2.1 x 10(6)-4.5 x 10(6)s(-1)M(-1)) upon adipocyte differentiation. The V(max) values for fatty acid transport in Caco-2 and HepG2 cells were essentially the same, yet the efficiency was 55% higher in Caco-2 cells (2.3 x 10(6)s(-1)M(-1) versus 1.5 x 10(6)s(-1)M(-1)). The kinetic parameters for fatty acid transport in three endothelial cell types demonstrated they were the least efficient cell types for this process giving V(max) values that were nearly 4-fold lower than those defined form 3T3-L1 adipocytes, Caco-2 cells and HepG2 cells. The

  17. Thermally activated charge transport in microbial protein nanowires

    PubMed Central

    Lampa-Pastirk, Sanela; Veazey, Joshua P.; Walsh, Kathleen A.; Feliciano, Gustavo T.; Steidl, Rebecca J.; Tessmer, Stuart H.; Reguera, Gemma

    2016-01-01

    The bacterium Geobacter sulfurreducens requires the expression of conductive protein filaments or pili to respire extracellular electron acceptors such as iron oxides and uranium and to wire electroactive biofilms, but the contribution of the protein fiber to charge transport has remained elusive. Here we demonstrate efficient long-range charge transport along individual pili purified free of metal and redox organic cofactors at rates high enough to satisfy the respiratory rates of the cell. Carrier characteristics were within the orders reported for organic semiconductors (mobility) and inorganic nanowires (concentration), and resistivity was within the lower ranges reported for moderately doped silicon nanowires. However, the pilus conductance and the carrier mobility decreased when one of the tyrosines of the predicted axial multistep hopping path was replaced with an alanine. Furthermore, low temperature scanning tunneling microscopy demonstrated the thermal dependence of the differential conductance at the low voltages that operate in biological systems. The results thus provide evidence for thermally activated multistep hopping as the mechanism that allows Geobacter pili to function as protein nanowires between the cell and extracellular electron acceptors. PMID:27009596

  18. Thermally activated charge transport in microbial protein nanowires.

    PubMed

    Lampa-Pastirk, Sanela; Veazey, Joshua P; Walsh, Kathleen A; Feliciano, Gustavo T; Steidl, Rebecca J; Tessmer, Stuart H; Reguera, Gemma

    2016-01-01

    The bacterium Geobacter sulfurreducens requires the expression of conductive protein filaments or pili to respire extracellular electron acceptors such as iron oxides and uranium and to wire electroactive biofilms, but the contribution of the protein fiber to charge transport has remained elusive. Here we demonstrate efficient long-range charge transport along individual pili purified free of metal and redox organic cofactors at rates high enough to satisfy the respiratory rates of the cell. Carrier characteristics were within the orders reported for organic semiconductors (mobility) and inorganic nanowires (concentration), and resistivity was within the lower ranges reported for moderately doped silicon nanowires. However, the pilus conductance and the carrier mobility decreased when one of the tyrosines of the predicted axial multistep hopping path was replaced with an alanine. Furthermore, low temperature scanning tunneling microscopy demonstrated the thermal dependence of the differential conductance at the low voltages that operate in biological systems. The results thus provide evidence for thermally activated multistep hopping as the mechanism that allows Geobacter pili to function as protein nanowires between the cell and extracellular electron acceptors. PMID:27009596

  19. Degradation of corticosteroids during activated sludge processing.

    PubMed

    Miyamoto, Aoi; Kitaichi, Yuko; Uchikura, Kazuo

    2014-01-01

    Laboratory tests of the decomposition of corticosteroids during activated sludge processing were investigated. Corticosteroid standards were added to activated sludge, and aliquots were regularly taken for analysis. The corticosteroids were extracted from the samples using a solid-phase extraction method and analyzed LC-MS. Ten types of corticosteroids were measured and roughly classified into three groups: 1) prednisolone, triamcinolone, betamethasone, prednisolone acetate, and hydrocortisone acetate, which decomposed within 4 h; 2) flunisolide, betamethasone valerate, and budesonide of which more than 50% remained after 4 h, but almost all of which decomposed within 24 h; and 3) triamcinolone acetonide, and fluocinolone acetonide of which more than 50% remained after 24 h. The decomposed ratio was correlated with each corticosteroid's Log P, especially groups 2) and 3). PMID:24390495

  20. Transport processes in partially saturate concrete: Testing and liquid properties

    NASA Astrophysics Data System (ADS)

    Villani, Chiara

    The measurement of transport properties of concrete is considered by many to have the potential to serve as a performance criterion that can be related to concrete durability. However, the sensitivity of transport tests to several parameters combined with the low permeability of concrete complicates the testing. Gas permeability and diffusivity test methods are attractive due to the ease of testing, their non-destructive nature and their potential to correlate to in-field carbonation of reinforced concrete structures. This work was aimed at investigating the potential of existing gas transport tests as a way to reliably quantify transport properties in concrete. In this study gas permeability and diffusivity test methods were analyzed comparing their performance in terms of repeatability and variability. The influence of several parameters was investigated such as moisture content, mixture proportions and gas flow. A closer look to the influence of pressure revealed an anomalous trend of permeability with respect to pressure. An alternative calculation is proposed in an effort to move towards the determination of intrinsic material properties that can serve as an input for service life prediction models. The impact of deicing salts exposure was also analyzed with respect to their alteration of the degree of saturation as this may affect gas transport in cementitious materials. Limited information were previously available on liquid properties over a wide range of concentrations. To overcome this limitation, this study quantified surface tension, viscosity in presence of deicing salts in a broad concentration range and at different temperatures. Existing models were applied to predict the change of fluid properties during drying. Vapor desorption isotherms were obtained to investigate the influence of deicing salts presence on the non-linear moisture diffusion coefficient. Semi-empirical models were used to quantify the initiation and the rate of drying using liquid

  1. Simple jumping process with memory: Transport equation and diffusion

    NASA Astrophysics Data System (ADS)

    Kamińska, A.; Srokowski, T.

    2004-06-01

    We present a stochastic jumping process, defined in terms of jump-size probability density and jumping rate, which is a generalization of the well-known kangaroo process. The definition takes into account two process values: after and before the jump. Therefore, the process is able to preserve memory about its previous values. It possesses a simple stationary limit. Its master equation is interpreted as the kinetic equation with variable collision rate. The process can be easily applied to model systems which relax to distributions other than Maxwellian. The case of a constant jumping rate corresponds to the diffusion process, either normal or ballistic.

  2. Allosteric Regulation of Transport Activity by Heterotrimerization of Arabidopsis Ammonium Transporter Complexes in Vivo[C][W][OA

    PubMed Central

    Yuan, Lixing; Gu, Riliang; Xuan, Yuanhu; Smith-Valle, Erika; Loqué, Dominique; Frommer, Wolf B.; von Wirén, Nicolaus

    2013-01-01

    Ammonium acquisition by plant roots is mediated by AMMONIUM TRANSPORTERs (AMTs), ubiquitous membrane proteins with essential roles in nitrogen nutrition in all organisms. In microbial and plant cells, ammonium transport activity is controlled by ammonium-triggered feedback inhibition to prevent cellular ammonium toxicity. Data from heterologous expression in yeast indicate that oligomerization of plant AMTs is critical for allosteric regulation of transport activity, in which the conserved cytosolic C terminus functions as a trans-activator. Employing the coexpressed transporters AMT1;1 and AMT1;3 from Arabidopsis thaliana as a model, we show here that these two isoforms form functional homo- and heterotrimers in yeast and plant roots and that AMT1;3 carrying a phosphomimic residue in its C terminus regulates both homo- and heterotrimers in a dominant-negative fashion in vivo. 15NH4+ influx studies further indicate that allosteric inhibition represses ammonium transport activity in roots of transgenic Arabidopsis expressing a phosphomimic mutant together with functional AMT1;3 or AMT1;1. Our study demonstrates in planta a regulatory role in transport activity of heterooligomerization of transporter isoforms, which may enhance their versatility for signal exchange in response to environmental triggers. PMID:23463773

  3. Theory of activated transport in bilayer quantum Hall systems.

    PubMed

    Roostaei, B; Mullen, K J; Fertig, H A; Simon, S H

    2008-07-25

    We analyze the transport properties of bilayer quantum Hall systems at total filling factor nu=1 in drag geometries as a function of interlayer bias, in the limit where the disorder is sufficiently strong to unbind meron-antimeron pairs, the charged topological defects of the system. We compute the typical energy barrier for these objects to cross incompressible regions within the disordered system using a Hartree-Fock approach, and show how this leads to multiple activation energies when the system is biased. We then demonstrate using a bosonic Chern-Simons theory that in drag geometries current in a single layer directly leads to forces on only two of the four types of merons, inducing dissipation only in the drive layer. Dissipation in the drag layer results from interactions among the merons, resulting in very different temperature dependences for the drag and drive layers, in qualitative agreement with experiment. PMID:18764355

  4. Theory of Activated Transport in Bilayer Quantum Hall Systems

    NASA Astrophysics Data System (ADS)

    Roostaei, Bahman; Fertig, Herbert; Mullen, Kieran; Simon, Steven

    2008-03-01

    We analyze the transport properties of bilayer quantum Hall systems at total filling factor ν= 1 in drag geometries as a function of interlayer bias, in the limit where the disorder is sufficiently strong to unbind meron-antimeron pairs, the charged topological defects of the system. We compute the typical energy barrier for these objects to cross incompressible regions within the disordered system using a Hartree-Fock approach, and show how this leads to multiple activation energies when the system is biased. We then demonstrate using a bosonic Chern- Simons theory that in drag geometries, current in a single layer directly leads to forces on only two of the four types of merons, inducing dissipation only in the drive layer. Dissipation in the drag layer results from interactions among the merons, resulting in very different temperature dependences for the drag and drive layers, in qualitative agreement with experiment. We conclude with predictions for future experiments.

  5. Theory of Activated Transport in Bilayer Quantum Hall Systems

    NASA Astrophysics Data System (ADS)

    Roostaei, B.; Mullen, K. J.; Fertig, H. A.; Simon, S. H.

    2008-07-01

    We analyze the transport properties of bilayer quantum Hall systems at total filling factor ν=1 in drag geometries as a function of interlayer bias, in the limit where the disorder is sufficiently strong to unbind meron-antimeron pairs, the charged topological defects of the system. We compute the typical energy barrier for these objects to cross incompressible regions within the disordered system using a Hartree-Fock approach, and show how this leads to multiple activation energies when the system is biased. We then demonstrate using a bosonic Chern-Simons theory that in drag geometries current in a single layer directly leads to forces on only two of the four types of merons, inducing dissipation only in the drive layer. Dissipation in the drag layer results from interactions among the merons, resulting in very different temperature dependences for the drag and drive layers, in qualitative agreement with experiment.

  6. Active transport of maltose in membrane vesicles obtained from Escherichia coli cells producing tethered maltose-binding protein.

    PubMed Central

    Dean, D A; Fikes, J D; Gehring, K; Bassford, P J; Nikaido, H

    1989-01-01

    Attempts to reconstitute periplasmic binding protein-dependent transport activity in membrane vesicles have often resulted in systems with poor and rather inconsistent activity, possibly because of the need to add a large excess of purified binding protein to the vesicles. We circumvented this difficulty by using a mutant which produces a precursor maltose-binding protein that is translocated across the cytoplasmic membrane but is not cleaved by the signal peptidase (J. D. Fikes and P. J. Bassford, Jr., J. Bacteriol. 169:2352-2359, 1987). The protein remains tethered to the cytoplasmic membrane, presumably through the hydrophobic signal sequence, and we show here that the spheroplasts and membrane vesicles prepared from this mutant catalyze active maltose transport without the addition of purified maltose-binding protein. In vesicles, the transport requires electron donors, such as ascorbate and phenazine methosulfate or D-lactate. However, inhibition by dicyclohexylcarbodiimide and stimulation of transport by the inculsion of ADP or ATP in the intravesicular space suggest that ATP (or compounds derived from it) is involved in the energization of the transport. The transport activity of intact cells can be recovered without much inactivation in the vesicles, and their high activity and ease of preparation will be useful in studies of the mechanism of the binding protein-dependent transport process. Images PMID:2644203

  7. Compromising KCC2 transporter activity enhances the development of continuous seizure activity.

    PubMed

    Kelley, Matthew R; Deeb, Tarek Z; Brandon, Nicholas J; Dunlop, John; Davies, Paul A; Moss, Stephen J

    2016-09-01

    Impaired neuronal inhibition has long been associated with the increased probability of seizure occurrence and heightened seizure severity. Fast synaptic inhibition in the brain is primarily mediated by the type A γ-aminobutyric acid receptors (GABAARs), ligand-gated ion channels that can mediate Cl(-) influx resulting in membrane hyperpolarization and the restriction of neuronal firing. In most adult brain neurons, the K(+)/Cl(-) co-transporter-2 (KCC2) establishes hyperpolarizing GABAergic inhibition by maintaining low [Cl(-)]i. In this study, we sought to understand how decreased KCC2 transport function affects seizure event severity. We impaired KCC2 transport in the 0-Mg(2+) ACSF and 4-aminopyridine in vitro models of epileptiform activity in acute mouse brain slices. Experiments with the selective KCC2 inhibitor VU0463271 demonstrated that reduced KCC2 transport increased the duration of SLEs, resulting in non-terminating discharges of clonic-like activity. We also investigated slices obtained from the KCC2-Ser940Ala (S940A) point-mutant mouse, which has a mutation at a known functional phosphorylation site causing behavioral and cellular deficits under hyperexcitable conditions. We recorded from the entorhinal cortex of S940A mouse brain slices in both 0-Mg(2+) ACSF and 4-aminopyridine, and demonstrated that loss of the S940 residue increased the susceptibility of continuous clonic-like discharges, an in vitro form of status epilepticus. Our experiments revealed KCC2 transport activity is a critical factor in seizure event duration and mechanisms of termination. Our results highlight the need for therapeutic strategies that potentiate KCC2 transport function in order to decrease seizure event severity and prevent the development of status epilepticus. PMID:27108931

  8. Erosion Processes, Sediment Transport and Hydrological Responses Due to Land Use Changes in Serbian Ski Resorts

    NASA Astrophysics Data System (ADS)

    Ristic, R.; Radic, B.; Vasiljevic, N.; Nikic, Z.; Malusevic, I.

    2012-04-01

    The construction or improvement of Serbian ski resorts provoked intensive erosion processes, sediment transport and hydrological responses due to land use changes, affecting the surrounding environment and even endangering the functionality of the built objects. The dominant disturbing activities (clear cuttings, trunk transport, machine grading of slopes, huge excavations, and access road construction) were followed by the activities during skiing and non skiing periods (skiing, usage of snow groomers, moving of vehicles and tourists, forestry activities and overgrazing). These activities put a lot of pressure on the environment, including the removal or compaction of the surface soil layer, the reduction of the infiltration capacity, the destruction or degradation of the vegetation cover, the intensifying of the surface runoff and the development of erosion processes. The most affected ski runs were surveyed (scale 1:1000) and all damages were mapped and classified during the summers of 2007-2010. The development of rills and gullies was measured at experimental plots (100x60 m), and the survey data were entered into a GIS application. The area sediment yield and the intensity of erosion processes were estimated on the basis of the "Erosion Potential Method"(EPM). The changes in hydrological conditions were estimated by comparing the computed values of maximal discharges in the conditions before and after massive activities in the ski resorts, as well as by using the local hydrological records. The determination of maximal discharges was achieved using a combined method: the synthetic unit hydrograph (maximum ordinate of unit runoff, qmax) and the Soil Conservation Service (SCS, 1979) methodology (deriving effective rainfall, Pe, from total precipitation, Pb). The determination was performed for AMC III (Antecedent Moisture Conditions III: high water content in the soil and significantly reduced infiltration capacity). The computations of maximal discharges were

  9. Modeling of coupled geochemical and transport processes: An overview

    SciTech Connect

    Carnahan, C.L.

    1989-10-01

    Early coupled models associated with fluid flow and solute transport have been limited by assumed conditions of constant temperature, fully saturated fluid flow, and constant pore fluid velocity. Developments including coupling of chemical reactions to variable fields of temperature and fluid flow have generated new requirements for experimental data. As the capabilities of coupled models expand, needs are created for experimental data to be used for both input and validation. 25 refs.

  10. Transport processes in magnetically confined plasmas in the nonlinear regime

    SciTech Connect

    Sonnino, Giorgio

    2006-06-15

    A field theory approach to transport phenomena in magnetically confined plasmas is presented. The thermodynamic field theory (TFT), previously developed for treating the generic thermodynamic system out of equilibrium, is applied to plasmas physics. Transport phenomena are treated here as the effect of the field linking the thermodynamic forces with their conjugate flows combined with statistical mechanics. In particular, the Classical and the Pfirsch-Schlueter regimes are analyzed by solving the thermodynamic field equations of the TFT in the weak-field approximation. We found that, the TFT does not correct the expressions of the ionic heat fluxes evaluated by the neoclassical theory in these two regimes. On the other hand, the fluxes of matter and electronic energy (heat flow) is further enhanced in the nonlinear Classical and Pfirsch-Schlueter regimes. These results seem to be in line with the experimental observations. The complete set of the electronic and ionic transport equations in the nonlinear Banana regime, is also reported. A paper showing the comparison between our theoretic results and the experimental observations in the JET machine is currently in preparation.

  11. Inhibition of ABC transport proteins by oil sands process affected water.

    PubMed

    Alharbi, Hattan A; Saunders, David M V; Al-Mousa, Ahmed; Alcorn, Jane; Pereira, Alberto S; Martin, Jonathan W; Giesy, John P; Wiseman, Steve B

    2016-01-01

    The ATP-binding cassette (ABC) superfamily of transporter proteins is important for detoxification of xenobiotics. For example, ABC transporters from the multidrug-resistance protein (MRP) subfamily are important for excretion of polycyclic aromatic hydrocarbons (PAHs) and their metabolites. Effects of chemicals in the water soluble organic fraction of relatively fresh oil sands process affected water (OSPW) from Base Mine Lake (BML-OSPW) and aged OSPW from Pond 9 (P9-OSPW) on the activity of MRP transporters were investigated in vivo by use of Japanese medaka at the fry stage of development. Activities of MRPs were monitored by use of the lipophilic dye calcein, which is transported from cells by ABC proteins, including MRPs. To begin to identify chemicals that might inhibit activity of MRPs, BML-OSPW and P9-OSPW were fractionated into acidic, basic, and neutral fractions by use of mixed-mode sorbents. Chemical compositions of fractions were determined by use of ultrahigh resolution orbitrap mass spectrometry in ESI(+) and ESI(-) mode. Greater amounts of calcein were retained in fry exposed to BML-OSPW at concentration equivalents greater than 1× (i.e., full strength). The neutral and basic fractions of BML-OSPW, but not the acidic fraction, caused greater retention of calcein. Exposure to P9-OSPW did not affect the amount of calcein in fry. Neutral and basic fractions of BML-OSPW contained relatively greater amounts of several oxygen-, sulfur, and nitrogen-containing chemical species that might inhibit MRPs, such as O(+), SO(+), and NO(+) chemical species, although secondary fractionation will be required to conclusively identify the most potent inhibitors. Naphthenic acids (O2(-)), which were dominant in the acidic fraction, did not appear to be the cause of the inhibition. This is the first study to demonstrate that chemicals in the water soluble organic fraction of OSPW inhibit activity of this important class of proteins. However, aging of OSPW attenuates

  12. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 2 2011-01-01 2011-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  13. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  14. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 2 2012-01-01 2012-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  15. MODELING COUPLED HYDROLOGICAL AND CHEMICAL PROCESSES: LONG-TERM URANIUM TRANSPORT FOLLOWING PHOSPHOROUS-FERTILIZATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Contaminants in the vadose zone are affected by the physical processes of water flow, heat movement and multicomponent transport, as well as generally by a range of interacting biogeochemical processes. Coupling these various processes within one integrated numerical simulator provides a process-ba...

  16. Hydrogen Transport to Mars Enables the Sabatier/Electrolysis Process

    NASA Technical Reports Server (NTRS)

    Mueller, P. J.; Rapp, D.

    1997-01-01

    The Sabatier/Electrolysis (S/E) process is an attractive approach to in situ propellant production (ISPP), and a breadboard demonstration of this process at Lockheed Martin Astronautics funded by JPL performed very well, with high conversion efficiency, and reliable diurnal operation. There is a net usage of hydrogen in the S/E process, and this has been the principal problem for this approach to ISPP.

  17. Active Transport Can Greatly Enhance Cdc20:Mad2 Formation

    PubMed Central

    Ibrahim, Bashar; Henze, Richard

    2014-01-01

    To guarantee genomic integrity and viability, the cell must ensure proper distribution of the replicated chromosomes among the two daughter cells in mitosis. The mitotic spindle assembly checkpoint (SAC) is a central regulatory mechanism to achieve this goal. A dysfunction of this checkpoint may lead to aneuploidy and likely contributes to the development of cancer. Kinetochores of unattached or misaligned chromosomes are thought to generate a diffusible “wait-anaphase” signal, which is the basis for downstream events to inhibit the anaphase promoting complex/cyclosome (APC/C). The rate of Cdc20:C-Mad2 complex formation at the kinetochore is a key regulatory factor in the context of APC/C inhibition. Computer simulations of a quantitative SAC model show that the formation of Cdc20:C-Mad2 is too slow for checkpoint maintenance when cytosolic O-Mad2 has to encounter kinetochores by diffusion alone. Here, we show that an active transport of O-Mad2 towards the spindle mid-zone increases the efficiency of Mad2-activation. Our in-silico data indicate that this mechanism can greatly enhance the formation of Cdc20:Mad2 and furthermore gives an explanation on how the “wait-anaphase” signal can dissolve abruptly within a short time. Our results help to understand parts of the SAC mechanism that remain unclear. PMID:25338047

  18. Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

    SciTech Connect

    Woodman, N.D. Rees-White, T.C.; Stringfellow, A.M.; Beaven, R.P.; Hudson, A.P.

    2015-04-15

    Highlights: • Multiple tracers were applied to saturated MSW to test dual-porosity properties. • Lithium demonstrated to be non-conservative as a tracer. • 260 mm diameter column too small to test transport properties of MSW. • The classical advection-dispersion mode was rejected due to high dispersivity. • Characteristic diffusion times did not vary with the tracer. - Abstract: Two column tests were performed in conditions emulating vertical flow beneath the leachate table in a biologically active landfill to determine dominant transport mechanisms occurring in landfills. An improved understanding of contaminant transport process in wastes is required for developing better predictions about potential length of the long term aftercare of landfills, currently measured in timescales of centuries. Three tracers (lithium, bromide and deuterium) were used. Lithium did not behave conservatively. Given that lithium has been used extensively for tracing in landfill wastes, the tracer itself and the findings of previous tests which assume that it has behaved conservatively may need revisiting. The smaller column test could not be fitted with continuum models, probably because the volume of waste was below a representative elemental volume. Modelling compared advection-dispersion (AD), dual porosity (DP) and hybrid AD–DP models. Of these models, the DP model was found to be the most suitable. Although there is good evidence to suggest that diffusion is an important transport mechanism, the breakthrough curves of the different tracers did not differ from each other as would be predicted based on the free-water diffusion coefficients. This suggested that solute diffusion in wastes requires further study.

  19. Serum- and glucocorticoid-inducible kinase sgk2 stimulates the transport activity of human organic anion transporters 1 by enhancing the stability of the transporter

    PubMed Central

    Xu, Da; Huang, Haozhe; Toh, May Fern; You, Guofeng

    2016-01-01

    Human organic anion transporter 1 (hOAT1) belongs to a family of organic anion transporters that play critical roles in the body disposition of clinically important drugs, including anti-viral therapeutics, anti-cancer drugs, antibiotics, antihypertensives, and anti-inflammatories. hOAT1 is abundantly expressed in the kidney and brain. In the current study, we examined the regulation of hOAT1 by serum- and glucocorticoid-inducible kinase 2 (sgk2) in the kidney COS-7 cells. We showed that sgk2 stimulated hOAT1 transport activity. Such stimulation mainly resulted from an increased cell surface expression of the transporter, kinetically revealed as an increased maximal transport velocity V max without significant change in substrate-binding affinity K m. We further showed that stimulation of hOAT1 activity by sgk2 was achieved by preventing hOAT1 degradation. Our co-immunoprecipitation experiment revealed that the effect of sgk2 on hOAT1 was through a direct interaction between these two proteins. In conclusion, our study demonstrated that sgk2 stimulates hOAT1 transport activity by enhancing the stability of the transporter. This study provides the insights into sgk2 regulation of hOAT1-mediated transport in normal physiology and disease. PMID:27335683

  20. Serum- and glucocorticoid-inducible kinase sgk2 stimulates the transport activity of human organic anion transporters 1 by enhancing the stability of the transporter.

    PubMed

    Xu, Da; Huang, Haozhe; Toh, May Fern; You, Guofeng

    2016-01-01

    Human organic anion transporter 1 (hOAT1) belongs to a family of organic anion transporters that play critical roles in the body disposition of clinically important drugs, including anti-viral therapeutics, anti-cancer drugs, antibiotics, antihypertensives, and anti-inflammatories. hOAT1 is abundantly expressed in the kidney and brain. In the current study, we examined the regulation of hOAT1 by serum- and glucocorticoid-inducible kinase 2 (sgk2) in the kidney COS-7 cells. We showed that sgk2 stimulated hOAT1 transport activity. Such stimulation mainly resulted from an increased cell surface expression of the transporter, kinetically revealed as an increased maximal transport velocity V max without significant change in substrate-binding affinity K m. We further showed that stimulation of hOAT1 activity by sgk2 was achieved by preventing hOAT1 degradation. Our co-immunoprecipitation experiment revealed that the effect of sgk2 on hOAT1 was through a direct interaction between these two proteins. In conclusion, our study demonstrated that sgk2 stimulates hOAT1 transport activity by enhancing the stability of the transporter. This study provides the insights into sgk2 regulation of hOAT1-mediated transport in normal physiology and disease. PMID:27335683

  1. Simulating Sediment Transport Processes in San Francisco Bay Using Coupled Hydrodynamic, Wave, and Sediment Transport Models

    NASA Astrophysics Data System (ADS)

    Bever, A. J.; MacWilliams, M.

    2012-12-01

    Under the conceptual model of sediment transport in San Pablo Bay, a sub-embayment of San Francisco Bay, proposed by Krone (1979), sediment typically enters San Pablo Bay during large winter and spring flows and is redistributed during summer conditions through wind wave resuspension and transport by tidal currents. A detailed understanding of how the waves and tides redistribute sediment within San Francisco Bay is critical for predicting how future sea level rise and a reduction in the sediment supply to the Bay will impact existing marsh and mudflat habitat, tidal marsh restoration projects, and ongoing maintenance dredging of the navigation channels. The three-dimensional UnTRIM San Francisco Bay-Delta Model was coupled with the Simulating WAves Nearshore (SWAN) wave model and the SediMorph morphological model, to develop a three-dimensional hydrodynamic, wind wave, and sediment transport model of the San Francisco Bay and the Sacramento-San Joaquin Delta. Numerical simulations of sediment resuspension due to tidal currents and wind waves and the subsequent transport of this sediment by tidal currents are used to quantify the spatial and temporal variability of sediment fluxes on the extensive shoals in San Pablo Bay under a range of tidal and wind conditions. The results demonstrate that suspended sediment concentration and sediment fluxes within San Pablo Bay are a complex product of tides and waves interacting spatially throughout the Bay, with concentrations responding to local resuspension and sediment advection. Sediment fluxes between the San Pablo Bay shoals and the deeper channel are highest during spring tides, and are elevated for up to a week following wave events, even though the greatest influence of the wave event occurs abruptly.

  2. Localization of the calcium-regulated citrate transport process in proximal tubule cells.

    PubMed

    Hering-Smith, Kathleen S; Mao, Weibo; Schiro, Faith R; Coleman-Barnett, Joycelynn; Pajor, Ana M; Hamm, L Lee

    2014-06-01

    Urinary citrate is an important inhibitor of calcium-stone formation. Most of the citrate reabsorption in the proximal tubule is thought to occur via a dicarboxylate transporter NaDC1 located in the apical membrane. OK cells, an established opossum kidney proximal tubule cell line, transport citrate but the characteristics change with extracellular calcium such that low calcium solutions stimulate total citrate transport as well as increase the apparent affinity for transport. The present studies address several fundamental properties of this novel process: the polarity of the transport process, the location of the calcium-sensitivity and whether NaDC1 is present in OK cells. OK cells grown on permeable supports exhibited apical >basolateral citrate transport. Apical transport of both citrate and succinate was sensitive to extracellular calcium whereas basolateral transport was not. Apical calcium, rather than basolateral, was the predominant determinant of changes in transport. Also 2,3-dimethylsuccinate, previously identified as an inhibitor of basolateral dicarboxylate transport, inhibited apical citrate uptake. Although the calcium-sensitive transport process in OK cells is functionally not typical NaDC1, NaDC1 is present in OK cells by Western blot and PCR. By immunolocalization studies, NaDC1 was predominantly located in discrete apical membrane or subapical areas. However, by biotinylation, apical NaDC1 decreases in the apical membrane with lowering calcium. In sum, OK cells express a calcium-sensitive/regulated dicarboxylate process at the apical membrane which responds to variations in apical calcium. Despite the functional differences of this process compared to NaDC1, NaDC1 is present in these cells, but predominantly in subapical vesicles. PMID:24652587

  3. XTP as a transport protocol for distributed parallel processing

    SciTech Connect

    Strayer, W.T.; Lewis, M.J.; Cline, R.E. Jr.

    1994-12-31

    The Xpress Transfer Protocol (XTP) is a flexible transport layer protocol designed to provide efficient service without dictating the communication paradigm or the delivery characteristics that quality the paradigm. XTP provides the tools to build communication services appropriate to the application. Current data delivery solutions for many popular cluster computing environments use TCP and UDP. We examine TCP, UDP, and XTP with respect to the communication characteristics typical of parallel applications. We perform measurements of end-to-end latency for several paradigms important to cluster computing. An implementation of XTP is shown to be comparable to TCP in end-to-end latency on preestablished connections, and does better for paradigms where connections must be constructed on the fly.

  4. DESCRIPTION OF ATMOSPHERIC TRANSPORT PROCESSES IN EULERIAN AIR QUALITY MODELS

    EPA Science Inventory

    Key differences among many types of air quality models are the way atmospheric advection and turbulent diffusion processes are treated. Gaussian models use analytical solutions of the advection-diffusion equations. Lagrangian models use a hypothetical air parcel concept effecti...

  5. Mutations in the diastrophic dysplasia sulfate transporter (DTDST) gene: correlation between sulfate transport activity and chondrodysplasia phenotype.

    PubMed

    Karniski, L P

    2001-07-01

    The diastrophic dysplasia sulfate transporter (DTDST) gene encodes a transmembrane protein that transports sulfate into chondrocytes to maintain adequate sulfation of proteoglycans. Mutations in this gene are responsible for four recessively inherited chondrodysplasias that include diastrophic dysplasia, multiple epiphyseal dysplasia, atelosteogenesis type 2 and achondrogenesis 1B (ACG-1B). To determine whether the DTDST mutations found in individuals with these chondrodysplasias differ functionally from each other, we compared the sulfate transport activity of 11 reported DTDST mutations. Five mutations, G255E, Delta a1751, L483P, R178X and N425D, had minimal sulfate transport function following expression in Xenopus laevis oocytes. Two mutations, Delta V340 and R279W, transported sulfate at rates of 17 and 32%, respectively, of wild-type DTDST. Four mutations, A715V, C653S, Q454P and G678V, had rates of sulfate transport nearly equal to that of wild-type DTDST. Transport kinetics were not different among the four mutations with near-normal sulfate transport function and wild-type DTDST. When the sulfate transport function of the different DTDST mutations are grouped according to the general phenotypes, individuals with the most severe form, ACG-1B, tend to be homozygous for null mutations, individuals with the moderately severe atelosteogenesis type 2 have at least one allele with a loss-of-function mutation, and individuals with the mildest forms are typically homozygous for mutations with residual sulfate transport function. However, in the X.laevis oocyte expression system, the correlation between residual transport function and the severity of phenotype was not absolute, suggesting that factors in addition to the intrinsic sulfate transport properties of the DTDST protein may influence the phenotype in individuals with DTDST mutations. PMID:11448940

  6. Alkaline pH activates the transport activity of GLUT1in L929 fibroblast cells

    PubMed Central

    Gunnink, Stephen M.; Kerk, Samuel A.; Kuiper, Benjamin D.; Alabi, Ola D.; Kuipers, David P.; Praamsma, Riemer C.; Wrobel, Kathryn E.; Louters, Larry L.

    2016-01-01

    The widely expressed mammalian glucose transporter, GLUT1, can be acutely activated in L929 fibroblast cells by a variety of conditions, including glucose deprivation, or treatment with various respiration inhibitors. Known thiol reactive compounds including phenylarsine oxide and nitroxyl are the fastest acting stimulators of glucose uptake, implicating cysteine biochemistry as critical to the acute activation of GLUT1. In this study, we report that in L929 cells glucose uptake increases 6-fold as the pH of the uptake solution is increased from 6 to 9 with the half-maximal activation at pH 7.5; consistent with the pKa of cysteine residues. This pH effect is essentially blocked by the pretreatment of the cells with either iodoacetamide or cinnamaldehyde, compounds that form covalent adducts with reduced cysteine residues. In addition, the activation by alkaline pH is not additive at pH 8 with known thiol reactive activators such as phenylarsine oxide or hydroxylamine. Kinetic analysis in L929 cells at pH 7 and 8 indicate that alkaline conditions both increases the Vmax and decreases the Km of transport. This is consistent with the observation that pH activation is additive to methylene blue, which activates uptake by increasing the Vmax, as well as to berberine, which activates uptake by decreasing the Km. This suggests that cysteine biochemistry is utilized in both methylene blue and berberine activation of glucose uptake. In contrast a pH increase from 7 to 8 in HCLE cells does not further activate glucose uptake. HCLE cells have a 25-fold higher basal glucose uptake rate than L929 cells and the lack of a pH effect suggests that the cysteine biochemistry has already occurred in HCLE cells. The data are consistent with pH having a complex mechanism of action, but one likely mediated by cysteine biochemistry. PMID:24333987

  7. Alkaline pH activates the transport activity of GLUT1 in L929 fibroblast cells.

    PubMed

    Gunnink, Stephen M; Kerk, Samuel A; Kuiper, Benjamin D; Alabi, Ola D; Kuipers, David P; Praamsma, Riemer C; Wrobel, Kathryn E; Louters, Larry L

    2014-04-01

    The widely expressed mammalian glucose transporter, GLUT1, can be acutely activated in L929 fibroblast cells by a variety of conditions, including glucose deprivation, or treatment with various respiration inhibitors. Known thiol reactive compounds including phenylarsine oxide and nitroxyl are the fastest acting stimulators of glucose uptake, implicating cysteine biochemistry as critical to the acute activation of GLUT1. In this study, we report that in L929 cells glucose uptake increases 6-fold as the pH of the uptake solution is increased from 6 to 9 with the half-maximal activation at pH 7.5; consistent with the pKa of cysteine residues. This pH effect is essentially blocked by the pretreatment of the cells with either iodoacetamide or cinnamaldehyde, compounds that form covalent adducts with reduced cysteine residues. In addition, the activation by alkaline pH is not additive at pH 8 with known thiol reactive activators such as phenylarsine oxide or hydroxylamine. Kinetic analysis in L929 cells at pH 7 and 8 indicate that alkaline conditions both increases the Vmax and decreases the Km of transport. This is consistent with the observation that pH activation is additive to methylene blue, which activates uptake by increasing the Vmax, as well as to berberine, which activates uptake by decreasing the Km. This suggests that cysteine biochemistry is utilized in both methylene blue and berberine activation of glucose uptake. In contrast a pH increase from 7 to 8 in HCLE cells does not further activate glucose uptake. HCLE cells have a 25-fold higher basal glucose uptake rate than L929 cells and the lack of a pH effect suggests that the cysteine biochemistry has already occurred in HCLE cells. The data are consistent with pH having a complex mechanism of action, but one likely mediated by cysteine biochemistry. PMID:24333987

  8. The association between access to public transportation and self-reported active commuting.

    PubMed

    Djurhuus, Sune; Hansen, Henning S; Aadahl, Mette; Glümer, Charlotte

    2014-12-01

    Active commuting provides routine-based regular physical activity which can reduce the risk of chronic diseases. Using public transportation involves some walking or cycling to a transit stop, transfers and a walk to the end location and users of public transportation have been found to accumulate more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number of transport modes were all positively associated with being an active commuter and with meeting recommendations of physical activity. No significant association was found between bus services at the nearest stop and active commuting. The results highlight the importance of including detailed measurements of access to public transit in order to identify the characteristics that facilitate the use of public transportation and active commuting. PMID:25489998

  9. The Association between Access to Public Transportation and Self-Reported Active Commuting

    PubMed Central

    Djurhuus, Sune; Hansen, Henning S.; Aadahl, Mette; Glümer, Charlotte

    2014-01-01

    Active commuting provides routine-based regular physical activity which can reduce the risk of chronic diseases. Using public transportation involves some walking or cycling to a transit stop, transfers and a walk to the end location and users of public transportation have been found to accumulate more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number of transport modes were all positively associated with being an active commuter and with meeting recommendations of physical activity. No significant association was found between bus services at the nearest stop and active commuting. The results highlight the importance of including detailed measurements of access to public transit in order to identify the characteristics that facilitate the use of public transportation and active commuting. PMID:25489998

  10. Evaluation of Proposed In Vivo Probe Substrates and Inhibitors for Phenotyping Transporter Activity in Humans.

    PubMed

    Momper, Jeremiah D; Tsunoda, Shirley M; Ma, Joseph D

    2016-07-01

    Drug transporters are present in various tissues and have a significant role in drug absorption, distribution, and elimination. The International Transporter Consortium has identified 7 transporters of increasing importance from evidence of clinically significant transporter-mediated drug-drug interactions. The transporters are P-glycoprotein, breast cancer resistance protein, organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic cation transporter 2, organic anion transporters (OAT) 1, and OAT3. Decision trees were created based on in vitro experiments to determine whether an in vivo transporter-mediated drug-drug interaction study is needed. Phenotyping is a methodology that evaluates real-time in vivo transporter activity, whereby changes in a probe substrate or probe inhibitor reflect alternations in the activity of the specified transporter. In vivo probe substrates and/or probe inhibitors have been proposed for each aforementioned transporter. In vitro findings and animal models provide the strongest evidence regarding probe specificity. However, such findings have not conclusively correlated with human phenotyping studies. Furthermore, the extent of contribution from multiple transporters in probe disposition complicates the ability to discern if study findings are the result of a specific transporter and thus provide a recommendation for a preferred probe for a drug transporter. PMID:27385182

  11. School Travel Planning: Mobilizing School and Community Resources to Encourage Active School Transportation

    ERIC Educational Resources Information Center

    Buliung, Ron; Faulkner, Guy; Beesley, Theresa; Kennedy, Jacky

    2011-01-01

    Background: Active school transport (AST), school travel using an active mode like walking, may be important to children's overall physical activity. A "school travel plan" (STP) documents a school's transport characteristics and provides an action plan to address school and neighborhood barriers to AST. Methods: We conducted a pilot STP…

  12. Magnetic Processing of Structural Components for Transportation Vehicles

    SciTech Connect

    Mackiewicz-Ludtka, G.; Ludtka, G. M.; Fleming, S.; del Prado Villasana, J.

    2011-09-30

    The specific goal of this project was to develop and evaluate the effect of magnetic processing as a viable and new technology to manufacture side‐rails for heavy trucks; and to demonstrate the applicability of this technology for an industrial truck/automotive process. The targeted performance enhancements for this project were to increase the hardness or strength of two families of alloys (comparable carbon contents but one alloy system incorporating hardenability improving additions of titanium and boron) by 15 to 20%. Thermomagnetic processing has been shown to make significant and unprecedented, simultaneous improvements in yield strength and ultimate tensile strength with no loss of ductility for the truck rail application investigated in this project. Improvements in the ultimate tensile strength and yield strength in the range 20 to 30% have been measured even for the lower hardenability alloy samples that only received a very low magnetic field tempering treatment at a tempering temperature that was 67% lower than the current non-magnetic field enhanced commercial process and for a brief tempering time of 20% of the time required in their current process at the higher temperature. These significant developments, that require further demonstration and investigation on current commercial and other alloy systems, promise the evolution of a much more energy efficient and lower-carbon footprint process to be used in the future to produce stronger, tougher, and lighter weight truck rails. The property increases in the truck rails themselves will enable lighter weight truck side-rails to be produced which will reduce the overall weight of heavy duty trucks which will reduce fuel consumption and be an enabler of the goals of the DOE EERE SuperTruck Program where fuel consumption reductions of 50% are targeted for the future generation of trucks.

  13. The Use of Transportable Processing Systems for the Treatment of Radioactive Nuclear Wastes

    SciTech Connect

    Phillips, Ch.; Houghton, D.; Crawford, G.

    2008-07-01

    EnergySolutions has developed two major types of radioactive processing plants based on its experience in the USA and UK, and its exclusive North American access to the intellectual property and know-how developed over 50 years at the Sellafield nuclear site in the UK. Passive Secure Cells are a type of hot cell used in place of the Canyons typically used in US-designed radioactive facilities. They are used in permanent, large scale plants suitable for long term processing of large amounts of radioactive material. The more recently developed Transportable Processing Systems, which are the subject of this paper, are used for nuclear waste processing and clean-up when processing is expected to be complete within shorter timescales and when it is advantageous to be able to move the processing equipment amongst a series of geographically spread-out waste treatment sites. Such transportable systems avoid the construction of a monolithic waste processing plant which itself would require extensive decommissioning and clean-up when its mission is complete. This paper describes a range of transportable radioactive waste processing equipment that EnergySolutions and its partners have developed including: the portable MOSS drum-based waste grouting system, the skid mounted MILWPP large container waste grouting system, the IPAN skid-mounted waste fissile content non-destructive assay system, the Wiped Film Evaporator low liquid hold-up transportable evaporator system, the CCPU transportable solvent extraction cesium separation system, and the SEP mobile shielded cells for emptying radioactive debris from water-filled silos. Maximum use is made of proven, robust, and compact processing equipment such as centrifugal contactors, remote sampling systems, and cement grout feed and metering devices. Flexible, elastomer-based Hose-in-Hose assemblies and container-based transportable pump booster stations are used in conjunction with these transportable waste processing units for

  14. Silver Nanoparticle Transport Through Soil: Illuminating the Pore-Scale Processes

    NASA Astrophysics Data System (ADS)

    Molnar, I. L.; Willson, C. S.; Gerhard, J.; O'Carroll, D. M.

    2015-12-01

    For nanoparticle transport through soil, the pore-scale (i.e., tens to hundreds of grains and pores) is a crucial intermediate scale which links nanoparticle-surface interactions with field-scale transport behaviour. However, very little information exists on how nanoparticles behave within real three-dimensional pore spaces. As a result, pore-scale processes are poorly characterized for nanoparticle systems and, subsequently, continuum-scale transport models struggle to describe commonly observed 'anomalous' behaviour such as extended tailing. This knowledge gap is due to two primary factors: an inability to experimentally observe nanoparticles within real pore spaces, and the computationally expensive models required to simulate nanoparticle movement. However, due to recent advances in Synchrotron X-Ray Computed Microtomography (SXCMT), it is now possible to quantify in-situ pore-scale nanoparticle concentrations during transport through real 3-dimensional porous media [1]. Employing this SXCMT quantification method to examine real nanoparticle/soil transport experiments has yielded new insights into the pore-scale processes governing nanoparticle transport. By coupling SXCMT nanoparticle quantification method with Computational Fluid Dynamics (CFD) simulations we are able to construct a better picture of how nanoparticles flow through real pore spaces. This talk presents SXCMT/CFD analyses of three silver nanoparticle transport experiments. Silver nanoparticles were flushed through three different sands to characterize the influence of grain distribution and retention rates on pore-scale flow and transport processes. These CFD/SXCMT analyses illuminate how processes such as temporary hydraulic retention govern nanoparticle transport. In addition, the observed distributions of pore water velocities and nanoparticle mass flow rates challenge the standard conceptual model of nanoparticle transport, suggesting that pore-scale processes require explicit consideration

  15. CALIBRATION OF SUBSURFACE BATCH AND REACTIVE-TRANSPORT MODELS INVOLVING COMPLEX BIOGEOCHEMICAL PROCESSES

    EPA Science Inventory

    In this study, the calibration of subsurface batch and reactive-transport models involving complex biogeochemical processes was systematically evaluated. Two hypothetical nitrate biodegradation scenarios were developed and simulated in numerical experiments to evaluate the perfor...

  16. A COMSOL-GEMS interface for modeling coupled reactive-transport geochemical processes

    NASA Astrophysics Data System (ADS)

    Azad, Vahid Jafari; Li, Chang; Verba, Circe; Ideker, Jason H.; Isgor, O. Burkan

    2016-07-01

    An interface was developed between COMSOL MultiphysicsTM finite element analysis software and (geo)chemical modeling platform, GEMS, for the reactive-transport modeling of (geo)chemical processes in variably saturated porous media. The two standalone software packages are managed from the interface that uses a non-iterative operator splitting technique to couple the transport (COMSOL) and reaction (GEMS) processes. The interface allows modeling media with complex chemistry (e.g. cement) using GEMS thermodynamic database formats. Benchmark comparisons show that the developed interface can be used to predict a variety of reactive-transport processes accurately. The full functionality of the interface was demonstrated to model transport processes, governed by extended Nernst-Plank equation, in Class H Portland cement samples in high pressure and temperature autoclaves simulating systems that are used to store captured carbon dioxide (CO2) in geological reservoirs.

  17. Are the correlates of active school transport context-specific?

    PubMed Central

    Larouche, R; Sarmiento, O L; Broyles, S T; Denstel, K D; Church, T S; Barreira, T V; Chaput, J-P; Fogelholm, M; Hu, G; Kuriyan, R; Kurpad, A; Lambert, E V; Maher, C; Maia, J; Matsudo, V; Olds, T; Onywera, V; Standage, M; Tremblay, M S; Tudor-Locke, C; Zhao, P; Katzmarzyk, P T

    2015-01-01

    OBJECTIVES: Previous research consistently indicates that children who engage in active school transport (AST) are more active than their peers who use motorized modes (car or bus). However, studies of the correlates of AST have been conducted predominantly in high-income countries and have yielded mixed findings. Using data from a heterogeneous sample of 12 country sites across the world, we investigated the correlates of AST in 9–11-year olds. METHODS: The analytical sample comprised 6555 children (53.8% girls), who reported their main travel mode to school and the duration of their school trip. Potential individual and neighborhood correlates of AST were assessed with a parent questionnaire adapted from previously validated instruments. Multilevel generalized linear mixed models (GLMM) were used to examine the associations between individual and neighborhood variables and the odds of engaging in AST while controlling for the child's school. Site moderated the relationship of seven of these variables with AST; therefore we present analyses stratified by site. RESULTS: The prevalence of AST varied from 5.2 to 79.4% across sites and the school-level intra-class correlation ranged from 0.00 to 0.56. For each site, the final GLMM included a different set of correlates of AST. Longer trip duration (that is, ⩾16 min versus ⩽15 min) was associated with lower odds of AST in eight sites. Other individual and neighborhood factors were associated with AST in three sites or less. CONCLUSIONS: Our results indicate wide variability in the prevalence and correlates of AST in a large sample of children from twelve geographically, economically and culturally diverse country sites. This suggests that AST interventions should not adopt a ‘one size fits all' approach. Future research should also explore the association between psychosocial factors and AST in different countries. PMID:27152191

  18. Field and theoretical aspects of explosive volcanic transport processes

    SciTech Connect

    Valentine, G.A.

    1988-12-01

    Chapter 1 presents results of a study of deposits at the base of the large-volume Peach Springs Tuff ignimbrite (referred to as layer 1). The layer 1 deposits are interpreted to record initial blasting and pyroclastic surge events at the beginning of the eruption. Changes in bedding structures with increasing flow distance are related to the decreasing sediment load of the surges and possibly to shocks in the surges. In Chapter 2 stratified glow theory is applied to pyroclastic surges. Particle transport is assumed to be turbulent suspension. The discussion centers on the Rouse, Froude, and Richardson numbers, and the Brunt-Vaisala frequency. Chapter 3 presents results of simulations Plinian eruption columns based upon numerical solution of the time-dependent, two-phase, compressible Navier-Stokes equations. Consideration of dimensionless groups define conditions leading to column collapse. Collapsing fountains form pyroclastic flows that consist of low-concentration fronts, relatively thick heads, vortex development along the top surfaces, and rising clouds of buoyant ash. The presence of coarse-grained proximal deposits primarily reflects tephra sorting within the eruption column before collapse. 154 refs., 32 figs., 2 tabs.

  19. Partial ages: diagnosing transport processes by means of multiple clocks

    NASA Astrophysics Data System (ADS)

    Mouchet, Anne; Cornaton, Fabien; Deleersnijder, Éric; Delhez, Éric J. M.

    2016-03-01

    The concept of age is widely used to quantify the transport rate of tracers - or pollutants - in the environment. The age focuses only on the time taken to reach a given location and disregards other aspects of the path followed by the tracer parcel. To keep track of the subregions visited by the tracer parcel along this path, partial ages are defined as the time spent in the different subregions. Partial ages can be computed in an Eulerian framework in much the same way as the usual age by extending the Constituent oriented Age and Residence Time theory (CART, www.climate.be/CART

  20. The pultrusion process for structures on advanced aerospace transportation systems

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Macconochie, Ian O.; Johnson, Gary S.

    1986-01-01

    The pultrusion process, which has the potential for use in the manufacture of structures for aerospace hardware, is described. In this process, reinforcing fibers are pulled continuously through a resin system for wetting and subsequently through a heated die for polymerization. By using this process, fabrication of very long lengths of high strength, lightweight structures with consistently high quality for aerospace applications is possible. The more conventional processes involve hand lay-up, vacuum bagging, autoclaving or oven curing techniques such that lengths of structural elements produced are limited by the lengths of autoclaves or curing ovens. Several types of developmental structural elements are described in which fiberglass, aramid, graphite, and hybrid fiber systems have been used as reinforcements in an epoxy matrix and their flexural properties compared. Reinforcement fibers having tailor-made orientations which achieve tailor-made strength in the pultrusions are described. The potential aerospace applications for the pultruded products are described with advantages cited over conventional hand lay-up methods.

  1. PROCESSES AFFECTING SUBSURFACE TRANSPORT OF LEAKING UNDERGROUND STORAGE TANK FLUIDS

    EPA Science Inventory

    The document focuses solely on the process affecting migration of fluids from a leaking tank and their effects on monitoring methodologies. Based upon the reviews presented, soil heterogeneities and the potential for multiphase flow will lead to high monitoring uncertainties if l...

  2. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... quality modeling do not preclude the consideration of alternatives in the NEPA process or other project... and TIP conformity with the NEPA process. 93.107 Section 93.107 Protection of Environment... Transit Laws § 93.107 Relationship of transportation plan and TIP conformity with the NEPA process....

  3. Evaluation of Transportation Vibration Associated with Relocation of Work in Process As Part of KCRIMS

    SciTech Connect

    Hartwig, Troy

    2013-04-01

    During relocation of the Kansas City Plant (KCP) from the site at Bannister Road to the site at Botts Road, work in process (WIP) within a production department must be transported. This report recommends packaging to mitigate vibration levels experienced by products during between-facility transportation. Measurements and analysis demonstrate that this mitigation results in vibration levels less than those experienced by the product during routine production processes within potentially damaging frequency ranges.

  4. Quasi-Three-Dimensional Mathematical Modeling of Morphological Processes Based on Equilibrium Sediment Transport

    NASA Astrophysics Data System (ADS)

    Charafi, My. M.; Sadok, A.; Kamal, A.; Menai, A.

    A quasi-three-dimensional mathematical model has been developed to study the morphological processes based on equilibrium sediment transport method. The flow velocities are computed by a two-dimensional horizontal depth-averaged flow model (H2D) in combination with logarithmic velocity profiles. The transport of sediment particles by a flow water has been considered in the form of bed load and suspended load. The bed load transport rate is defined as the transport of particles by rolling and saltating along the bed surface and is given by the Van Rijn relationship (1987). The equilibrium suspended load transport is described in terms of an equilibrium sediment concentration profile (ce) and a logarithmic velocity (u). Based on the equilibrium transport, the bed change rate is given by integration of the sediment mass-balance equation. The model results have been compared with a Van Rijn results (equilibrium approach) and good agreement has been found.

  5. Grout pump selection process for the Transportable Grout Facility

    SciTech Connect

    McCarthy, D.; Treat, R.L.

    1985-01-01

    Selected low-level radioactive liquid wastes at Hanford will be disposed by grouting. Grout is formed by mixing the liquid wastes with solid materials, including Portland cement, fly ash, and clay. The mixed grouts will be pumped to disposal sites (e.g., trenches and buried structures) where the grout will be allowed to harden and, thereby, immobilize the wastes. A Transportable Grout Facility (TGF) will be constructed and operated by Rockwell Hanford Operations to perform the grouting function. A critical component of the TGF is the grout pump. A preliminary review of pumping requirements identified reciprocating pumps and progressive cavity pumps as the two classes of pumps best suited for the application. The advantages and disadvantages of specific types of pumps within these two classes were subsequently investigated. As a result of this study, the single-screw, rotary positive displacement pump was identified as the best choice for the TGF application. This pump has a simple design, is easy to operate, is rugged, and is suitable for a radioactive environment. It produces a steady, uniform flow that simplifies suction and discharge piping requirements. This pump will likely require less maintenance than reciprocating pumps and can be disassembled rapidly and decontaminated easily. If the TGF should eventually require discharge pressures in excess of 500 psi, a double-acting duplex piston pump is recommended because it can operate at low speed, with only moderate flow rate fluctuations. However, the check valves, stuffing box, piston, suction, and discharge piping must be designed carefully to allow trouble-free operations.

  6. Identification of sorption processes and parameters for radionuclide transport in fractured rock

    NASA Astrophysics Data System (ADS)

    Dai, Zhenxue; Wolfsberg, Andrew; Reimus, Paul; Deng, Hailin; Kwicklis, Edward; Ding, Mei; Ware, Doug; Ye, Ming

    2012-01-01

    SummaryIdentification of chemical reaction processes in subsurface environments is a key issue for reactive transport modeling because simulating different processes requires developing different chemical-mathematical models. In this paper, two sorption processes (equilibrium and kinetics) are considered for modeling neptunium and uranium sorption in fractured rock. Based on different conceptualizations of the two processes occurring in fracture and/or matrix media, seven dual-porosity, multi-component reactive transport models are developed. The process models are identified with a stepwise strategy by using multi-tracer concentration data obtained from a series of transport experiments. In the first step, breakthrough data of a conservative tracer (tritium) obtained from four experiments are used to estimate the flow and non-reactive transport parameters (i.e., mean fluid residence time in fracture, fracture aperture, and matrix tortuosity) common to all the reactive transport models. In the second and third steps, by fixing the common non-reactive flow and transport parameters, the sorption parameters (retardation factor, sorption coefficient, and kinetic rate constant) of each model are estimated using the breakthrough data of reactive tracers, neptunium and uranium, respectively. Based on the inverse modeling results, the seven sorption-process models are discriminated using four model discrimination (or selection) criteria, Akaike information criterion ( AIC), modified Akaike information criterion ( AICc), Bayesian information criterion ( BIC) and Kashyap information criterion ( KIC). These criteria suggest the kinetic sorption process for modeling reactive transport of neptunium and uranium transport in both fracture and matrix. This conclusion is confirmed by two chemical criteria, the half reaction time and Damköhler number criterion.

  7. Mechanistic determinants of the directionality and energetics of active export by a heterodimeric ABC transporter

    DOE PAGESBeta

    Grossmann, Nina; Vakkasoglu, Ahmet S.; Hulpke, Sabine; Abele, Rupert; Gaudet, Rachelle; Tampé, Robert

    2014-11-07

    The ATP-binding cassette (ABC) transporter associated with antigen processing (TAP) participates in immune surveillance by moving proteasomal products into the endoplasmic reticulum (ER) lumen for major histocompatibility complex class I loading and cell surface presentation to cytotoxic T cells. Here we delineate the mechanistic basis for antigen translocation. Notably, TAP works as a molecular diode, translocating peptide substrates against the gradient in a strict unidirectional way. We reveal the importance of the D-loop at the dimer interface of the two nucleotide-binding domains (NBDs) in coupling substrate translocation with ATP hydrolysis and defining transport vectoriality. Substitution of the converved aspartate, whichmore » coordinates the ATP-binding site, decreases NBD dimerization affinity and turns the unidirectional primary active pump into a passive bidirectional nucleotide-gated facilitator. Thus, ATP hydrolysis is not required for translocation per se, but is essential for both active and unidirectional transport. As a result, our data provide detailed mechanistic insight into how heterodimeric ABC exporters operate.« less

  8. Mechanistic determinants of the directionality and energetics of active export by a heterodimeric ABC transporter

    SciTech Connect

    Grossmann, Nina; Vakkasoglu, Ahmet S.; Hulpke, Sabine; Abele, Rupert; Gaudet, Rachelle; Tampé, Robert

    2014-11-07

    The ATP-binding cassette (ABC) transporter associated with antigen processing (TAP) participates in immune surveillance by moving proteasomal products into the endoplasmic reticulum (ER) lumen for major histocompatibility complex class I loading and cell surface presentation to cytotoxic T cells. Here we delineate the mechanistic basis for antigen translocation. Notably, TAP works as a molecular diode, translocating peptide substrates against the gradient in a strict unidirectional way. We reveal the importance of the D-loop at the dimer interface of the two nucleotide-binding domains (NBDs) in coupling substrate translocation with ATP hydrolysis and defining transport vectoriality. Substitution of the converved aspartate, which coordinates the ATP-binding site, decreases NBD dimerization affinity and turns the unidirectional primary active pump into a passive bidirectional nucleotide-gated facilitator. Thus, ATP hydrolysis is not required for translocation per se, but is essential for both active and unidirectional transport. As a result, our data provide detailed mechanistic insight into how heterodimeric ABC exporters operate.

  9. Sediment transport processes from the topset to the foreset of a crenulated clinoform (Adriatic Sea)

    NASA Astrophysics Data System (ADS)

    Puig, P.; Ogston, A. S.; Guillén, J.; Fain, A. M. V.; Palanques, A.

    2007-02-01

    Crenulated clinoforms of complex and uncertain origin characterize large portions of the Late-Holocene prograding mud wedge in the western Adriatic continental shelf. Sediment failure was originally postulated as the most plausible mechanism for the formation of the crenulations. Subsequent work has shown that, although the origin of the crenulations may have been related to deformation processes, their maintenance through time seems to be better explained by different sediment accumulation rates in the flat and steep flanks. In order to establish relationships between active sediment dynamics, across-shelf transport and sediment accumulation in these crenulated clinoforms, two tripods and a mooring were deployed off the Pescara River during autumn and winter 2002-2003 as part of the EuroSTRATAFORM program, and in combination with the Po and Apennine Sediment Transport and Accumulation (PASTA) study. The tripods were placed on the shallow topset region and close to the clinoform roll-over point (i.e., offlap break), at 12 and 20-m water depth, respectively, and the mooring was located at 50-m depth, in the crenulated foreset region. Several sediment-resuspension events were recorded, mainly related to Bora and Sirocco storms, during which wave-orbital and current velocities increased considerably. Sediment transport in the topset region was predominantly towards the SE, following the direction of the coastal current and the bathymetry, but showing a significant offshore component at the roll-over point that was intensified during storm events. Currents at the foreset region were also directed to the SE. In mid-waters they were clearly aligned with the local bathymetry, whereas near the bottom they had an important and persistent offshore component. This current behavior seems to be associated with an intense bottom Ekman transport that causes the near-bottom current to be deflected to the left (i.e., offshore) with respect to the direction of the surface current

  10. Propulsion/ASME Rocket-Based Combined Cycle Activities in the Advanced Space Transportation Program Office

    NASA Technical Reports Server (NTRS)

    Hueter, Uwe; Turner, James

    1998-01-01

    NASA's Office Of Aeronautics and Space Transportation Technology (OASTT) has establish three major coals. "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville,Ala. focuses on future space transportation technologies under the "Access to Space" pillar. The Advanced Reusable Technologies (ART) Project, part of ASTP, focuses on the reusable technologies beyond those being pursued by X-33. The main activity over the past two and a half years has been on advancing the rocket-based combined cycle (RBCC) technologies. In June of last year, activities for reusable launch vehicle (RLV) airframe and propulsion technologies were initiated. These activities focus primarily on those technologies that support the year 2000 decision to determine the path this country will take for Space Shuttle and RLV. In February of this year, additional technology efforts in the reusable technologies were awarded. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion. Aerojet, Boeing-Rocketdyne and Pratt & Whitney were selected for a two-year period to design, build and ground test their RBCC engine concepts. In addition, ASTROX, Pennsylvania State University (PSU) and University of Alabama in Huntsville also conducted supporting activities. The activity included ground testing of components (e.g., injectors, thrusters, ejectors and inlets) and integrated flowpaths. An area that has caused a large amount of difficulty in the testing efforts is the means of initiating the rocket combustion process. All three of the prime contractors above were using silane (SiH4) for ignition of the thrusters. This follows from the successful use of silane in the NASP program for scramjet ignition. However, difficulties were immediately encountered when silane (an 80/20 mixture of hydrogen/silane) was used for rocket

  11. Prospect on the Atomic and Molecular Processes in Plasmas 4. Transport Code 4.1 Radiation Transport Code

    NASA Astrophysics Data System (ADS)

    Takabe, Hideaki

    A brief review is given of the physics of radiation transport, a topic that is important in the study of astrophysics, laser-plasmas, divertor-plasmas, etc. In general, we must solve non-local thermodynamic equilibrium processes using an appropriate atomic model. The resultant data related to the spectral emissivity and opacity of partially ionized plasmas are then used to solve the radiation transfer equation. In this note, I briefly overview a variety of ways to carry out such a calculation. In addition, similarities and differences in the physical process between laser-plasmas and divertor-plasmas are briefly described.

  12. Thermodynamics of peptide binding to the transporter associated with antigen processing (TAP).

    PubMed

    Neumann, Lars; Abele, Rupert; Tampé, Robert

    2002-12-13

    The ATP-binding cassette (ABC) transporter TAP plays an essential role in antigen processing and immune response to infected or malignant cells. TAP translocates proteasomal degradation products from the cytosol into the endoplasmic reticulum, where MHC class I molecules are loaded with these peptides. Kinetically stable peptide-MHC complexes are transported to the cell surface for inspection by cytotoxic T lymphocytes. The transport cycle of TAP is initiated by peptide binding, which is responsible for peptide selection and for stimulation of ATP-hydrolysis and subsequent translocation. Here we have analysed the driving forces for the formation of the peptide-TAP complex by kinetic and thermodynamic methods. First, the apparent peptide association and dissociation rates were determined at various temperatures. Strikingly, very high activation energies for apparent association (E(a)(ass)=106 kJmol(-1)) and dissociation (E(a)(diss)=80 kJmol(-1)) of the peptide-TAP complex were found. Next, the temperature-dependence of the peptide affinity constants was investigated by equilibrium-binding assays. Along with calculations of free enthalpy deltaG, enthalpy deltaH and entropy deltaS, a large positive change in heat capacity was resolved (deltaC degrees =23 kJmol(-1)K(-1)), indicating a fundamental structural reorganization of the TAP complex upon peptide binding. The inspection of the conformational entropy reveals that approximately one-fourth of all TAP residues is rearranged. These thermodynamic studies indicate that at physiological temperature, peptide binding is endothermic and driven by entropy. PMID:12470952

  13. Transport processes investigation: A necessary first step in site scale characterization plans

    SciTech Connect

    Roepke, C.; Glass, R.J.; Brainard, J.; Mann, M.; Kriel, K.; Holt, R.; Schwing, J.

    1995-03-01

    We propose an approach, which we call the Transport Processes Investigation or TPI, to identify and verify site-scale transport processes and their controls. The TPI aids in the formulation of an accurate conceptual model of flow and transport, an essential first step in the development of a cost effective site characterization strategy. The TPI is demonstrated in the highly complex vadose zone of glacial tills that underlie the Fernald Environmental Remediation Project (FEMP) in Fernald, Ohio. As a result of the TPI, we identify and verify the pertinent flow processes and their controls, such as extensive macropore and fracture flow through layered clays, which must be included in an accurate conceptual model of site-scale contaminant transport. We are able to conclude that the classical modeling and sampling methods employed in some site characterization programs will be insufficient to characterize contaminant concentrations or distributions at contaminated or hazardous waste facilities sited in such media.

  14. Degassing Processes at Persistently Active Explosive Volcanoes

    NASA Astrophysics Data System (ADS)

    Smekens, Jean-Francois

    Among volcanic gases, sulfur dioxide (SO2) is by far the most commonly measured. More than a monitoring proxy for volcanic degassing, SO 2 has the potential to alter climate patterns. Persistently active explosive volcanoes are characterized by short explosive bursts, which often occur at periodic intervals numerous times per day, spanning years to decades. SO 2 emissions at those volcanoes are poorly constrained, in large part because the current satellite monitoring techniques are unable to detect or quantify plumes of low concentration in the troposphere. Eruption plumes also often show high concentrations of ash and/or aerosols, which further inhibit the detection methods. In this work I focus on quantifying volcanic gas emissions at persistently active explosive volcanoes and their variations over short timescales (minutes to hours), in order to document their contribution to natural SO2 flux as well as investigate the physical processes that control their behavior. In order to make these measurements, I first develop and assemble a UV ground-based instrument, and validate it against an independently measured source of SO2 at a coal-burning power plant in Arizona. I establish a measurement protocol and demonstrate that the instrument measures SO 2 fluxes with < 20 % error. Using the same protocol, I establish a record of the degassing patterns at Semeru volcano (Indonesia), a volcano that has been producing cycles of repeated explosions with periods of minutes to hours for the past several decades. Semeru produces an average of 21-71 tons of SO2 per day, amounting to a yearly output of 8-26 Mt. Using the Semeru data, along with a 1-D transient numerical model of magma ascent, I test the validity of a model in which a viscous plug at the top of the conduit produces cycles of eruption and gas release. I find that it can be a valid hypothesis to explain the observed patterns of degassing at Semeru. Periodic behavior in such a system occurs for a very narrow range

  15. Evaluation of Activity Concentration Values and Doses due to the Transport of Low Level Radioactive Material

    SciTech Connect

    Rawl, Richard R; Scofield, Patricia A; Leggett, Richard Wayne; Eckerman, Keith F

    2010-04-01

    The International Atomic Energy Agency (IAEA) initiated an international Coordinated Research Project (CRP) to evaluate the safety of transport of naturally occurring radioactive material (NORM). This report presents the United States contribution to that IAEA research program. The focus of this report is on the analysis of the potential doses resulting from the transport of low level radioactive material. Specific areas of research included: (1) an examination of the technical approach used in the derivation of exempt activity concentration values and a comparison of the doses associated with the transport of materials included or not included in the provisions of Paragraph 107(e) of the IAEA Safety Standards, Regulations for the Safe Transport of Radioactive Material, Safety Requirements No. TS-R-1; (2) determination of the doses resulting from different treatment of progeny for exempt values versus the A{sub 1}/A{sub 2} values; and (3) evaluation of the dose justifications for the provisions applicable to exempt materials and low specific activity materials (LSA-I). It was found that the 'previous or intended use' (PIU) provision in Paragraph 107(e) is not risk informed since doses to the most highly exposed persons (e.g., truck drivers) are comparable regardless of intended use of the transported material. The PIU clause can also have important economic implications for co-mined ores and products that are not intended for the fuel cycle but that have uranium extracted as part of their industrial processing. In examination of the footnotes in Table 2 of TS-R-1, which identifies the progeny included in the exempt or A1/A2 values, there is no explanation of how the progeny were selected. It is recommended that the progeny for both the exemption and A{sub 1}/A{sub 2} values should be similar regardless of application, and that the same physical information should be used in deriving the limits. Based on the evaluation of doses due to the transport of low-level NORM

  16. Environmental impact assessment in urban transport planning: Exploring process-related barriers in Spanish practice

    SciTech Connect

    Soria-Lara, Julio A. Bertolini, Luca Brömmelstroet, Marco te

    2015-01-15

    The effectiveness of EIA for evaluating transport planning projects is increasingly being questioned by practitioners, institutions and scholars. The academic literature has traditionally focused more on solving content-related problems with EIA (i.e. the measurement of environmental effects) than on process-related issues (i.e. the role of EIA in the planning process and the interaction between key actors). Focusing only on technical improvements is not sufficient for rectifying the effectiveness problems of EIA. In order to address this knowledge gap, the paper explores how EIA is experienced in the Spanish planning context and offers in-depth insight into EIA process-related issues in the field of urban transport planning. From the multitude of involved actors, the research focuses on exploring the perceptions of the two main professional groups: EIA developers and transport planners. Through a web-based survey we assess the importance of process-related barriers to the effective use of EIA in urban transport planning. The analyses revealed process issues based fundamentally on unstructured stakeholders involvement and an inefficient public participation - Highlights: • Qualitative research on perceptions of EIA participants on EIA processes. • Web-based survey with different participants (EIA-developers; transport planners). • It was seen an inefficient participation of stakeholders during the EIA processes.

  17. Synthesis and Structure–Activity Relationships of Pteridine Dione and Trione Monocarboxylate Transporter 1 Inhibitors

    PubMed Central

    2015-01-01

    Novel substituted pteridine-derived inhibitors of monocarboxylate transporter 1 (MCT1), an emerging target for cancer therapy, are reported. The activity of these compounds as inhibitors of lactate transport was confirmed using a 14C-lactate transport assay, and their potency against MCT1-expressing human tumor cells was established using MTT assays. The four most potent compounds showed substantial anticancer activity (EC50 37–150 nM) vs MCT1-expressing human Raji lymphoma cells. PMID:25068893

  18. Transport phenomena of reactive fluid flow in heterogeneous combustion processes.

    NASA Technical Reports Server (NTRS)

    Hung, W. S. Y.; Chen, C. S.; Haviland, J. K.

    1972-01-01

    A previously developed computer program was used to model two transient hybrid combustion processes involving tubes of solid Plexiglas. In the first study, representing combustion of a hybrid rocket, the oxidizing gas was oxygen, and calculations were continued sufficiently long to obtain steady-state values. Systematic variations were made in reaction rate constant, mass flow rate, and pressure, alternatively using constant and temperature dependent regression rate models for the fuel surface. Consistent results were obtained, as is evidenced by the values for the mass function of the reaction product and the flame temperature, for which plots are supplied. In the second study, fire initiation in a duct was studied, with an air mixture as the oxidizing gas. It was demonstrated that a satisfactory flame spread mechanism could be reproduced on the computer. In both of the above applications, the general, transient, two-dimensional conservation equations were represented, together with chemical reactions, solid-fuel interface conditions, and heat conduction in the solid fuel.

  19. The impact of different sediment concentrations and sediment transport formulas on the simulated floodplain processes

    NASA Astrophysics Data System (ADS)

    Benjankar, Rohan; Yager, Elowyn M.

    2012-07-01

    SummaryOverbank sedimentation is an important process in river floodplain ecosystems and is a component of the floodplain geomorphologic evolution. The impact of suspended sediment supply on floodplain processes is still unclear because sediment deposition can be influenced by many factors. We quantified the effect of sediment supply (suspended sediment) and transport formulas on simulated floodplain processes using a coupled two-dimensional hydrodynamic and sediment transport model (MIKE21C). Erosion and deposition depths, net sedimentation depth and total volume were quantified based on the last time step of the simulation period. The MIKE21C model was validated by comparing simulated water surface elevations to those from a one-dimensional hydrodynamic model. We compared the sediment transport model simulated suspended sediment concentrations (SSCs) to measured concentrations at a gage station. Erosion and deposition processes were simulated using five hydrograph scenarios as a function of high and low SSC and two sediment transport equations, Van Rijn (1984) and Engelund and Hansen (1967). A specific location could be an erosional or depositional zone at different time steps of the simulation. Thus, floodplain deposition is a discontinuous function of river discharge and varies spatially and temporally over the floodplain. Large flows with high SSC were more effective for floodplain deposition than lower discharges, which dominantly caused sediment scour. Coupled hydrodynamic and sediment transport models that account for feedback processes between topography and hydraulics should be given first preference for future floodplain restoration projects. From a restoration perspective, larger flows are required for greater floodplain deposition rates and maintenance of dynamic processes. The Engelund and Hansen (1967) equation simulated higher transport rates than the Van Rijn equation (1984). For future studies, transport equations should be selected based on the

  20. Regulation of the creatine transporter by AMP-activated protein kinase in kidney epithelial cells

    PubMed Central

    Li, Hui; Thali, Ramon F.; Smolak, Christy; Gong, Fan; Alzamora, Rodrigo; Wallimann, Theo; Scholz, Roland; Pastor-Soler, Núria M.; Neumann, Dietbert

    2010-01-01

    The metabolic sensor AMP-activated protein kinase (AMPK) regulates several transport proteins, potentially coupling transport activity to cellular stress and energy levels. The creatine transporter (CRT; SLC6A8) mediates creatine uptake into several cell types, including kidney epithelial cells, where it has been proposed that CRT is important for reclamation of filtered creatine, a process critical for total body creatine homeostasis. Creatine and phosphocreatine provide an intracellular, high-energy phosphate-buffering system essential for maintaining ATP supply in tissues with high energy demands. To test our hypothesis that CRT is regulated by AMPK in the kidney, we examined CRT and AMPK distribution in the kidney and the regulation of CRT by AMPK in cells. By immunofluorescence staining, we detected CRT at the apical pole in a polarized mouse S3 proximal tubule cell line and in native rat kidney proximal tubules, a distribution overlapping with AMPK. Two-electrode voltage-clamp (TEV) measurements of Na+-dependent creatine uptake into CRT-expressing Xenopus laevis oocytes demonstrated that AMPK inhibited CRT via a reduction in its Michaelis-Menten Vmax parameter. [14C]creatine uptake and apical surface biotinylation measurements in polarized S3 cells demonstrated parallel reductions in creatine influx and CRT apical membrane expression after AMPK activation with the AMP-mimetic compound 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside. In oocyte TEV experiments, rapamycin and the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5′-monophosphate (ZMP) inhibited CRT currents, but there was no additive inhibition of CRT by ZMP, suggesting that AMPK may inhibit CRT indirectly via the mammalian target of rapamycin pathway. We conclude that AMPK inhibits apical membrane CRT expression in kidney proximal tubule cells, which could be important in reducing cellular energy expenditure and unnecessary creatine reabsorption under conditions of local

  1. Spatial correlations, additivity, and fluctuations in conserved-mass transport processes

    NASA Astrophysics Data System (ADS)

    Das, Arghya; Chatterjee, Sayani; Pradhan, Punyabrata

    2016-06-01

    We exactly calculate two-point spatial correlation functions in steady state in a broad class of conserved-mass transport processes, which are governed by chipping, diffusion, and coalescence of masses. We find that the spatial correlations are in general short-ranged and, consequently, on a large scale, these transport processes possess a remarkable thermodynamic structure in the steady state. That is, the processes have an equilibrium-like additivity property and, consequently, a fluctuation-response relation, which help us to obtain subsystem mass distributions in the limit of subsystem size large.

  2. Neoclassical plasma viscosity and transport processes in non-axisymmetric tori

    NASA Astrophysics Data System (ADS)

    Shaing, K. C.; Ida, K.; Sabbagh, S. A.

    2015-11-01

    Neoclassical transport processes are important to the understanding of plasma confinement physics in doubly periodic magnetized toroidal plasmas, especially, after the impact of the momentum confinement on the particle and energy confinement is recognized. Real doubly periodic tori in general are non-axisymmetric, with symmetric tori as a special case. An eight-moment approach to transport theory with plasma density N, plasma pressure p, mass flow velocity V and heat flow q as independent variables is adopted. Transport processes are dictated by the solutions of the momentum and heat flux balance equations. For toroidal plasma confinement devices, the first order (in the gyro-radius ordering) plasma flows are on the magnetic surface to guarantee good plasma confinement and are thus two-dimensional. Two linearly independent components of the momentum equation are required to determine the flows completely. Once this two-dimensional flow is relaxed, i.e. the momentum equation reaches a steady state, plasmas become ambipolar, and all the transport fluxes are determined through the flux-force relation. The flux-force relation is derived both from the kinetic definitions for the transport fluxes and from the manipulation of the momentum and heat flux balance equations to illustrate the nature of the transport fluxes by examining their corresponding driven forces and their roles in the momentum and heat flux balance equations. Steady-state plasma flows are determined by the components of the stress and heat stress tensors in the momentum and heat flux balance equations. This approach emphasizes the pivotal role of the momentum equation in the transport processes and is particularly useful in modelling plasma flows in experiments. The methodology for neoclassical transport theory is applied to fluctuation-driven transport fluxes in the quasilinear theory to unify these two theories. Experimental observations in tokamaks and stellarators for the physics discussed are

  3. Imaging on a Shoestring: Cost-Effective Technologies for Probing Vadose Zone Transport Processes

    NASA Astrophysics Data System (ADS)

    Corkhill, C.; Bridge, J. W.; Barns, G.; Fraser, R.; Romero-Gonzalez, M.; Wilson, R.; Banwart, S.

    2010-12-01

    Key barriers to the widespread uptake of imaging technology for high spatial resolution monitoring of porous media systems are cost and accessibility. X-ray tomography, magnetic resonance imaging (MRI), gamma and neutron radiography require highly specialised equipment, controlled laboratory environments and/or access to large synchrotron facilities. Here we present results from visible light, fluorescence and autoradiographic imaging techniques developed at low cost and applied in standard analytical laboratories, adapted where necessary at minimal capital expense. UV-visible time lapse fluorescence imaging (UV-vis TLFI) in a transparent thin bed chamber enabled microspheres labelled with fluorescent dye and a conservative fluorophore solute (disodium fluorescein) to be measured simultaneously in saturated, partially-saturated and actively draining quartz sand to elucidate empirical values for colloid transport and deposition parameters distributed throughout the flow field, independently of theoretical approximations. Key results include the first experimental quantification of the effects of ionic strength and air-water interfacial area on colloid deposition above a capillary fringe, and the first direct observations of particle mobilisation and redeposition by moving saturation gradients during drainage. UV-vis imaging was also used to study biodegradation and reactive transport in a variety of saturated conditions, applying fluorescence as a probe for oxygen and nitrate concentration gradients, pH, solute transport parameters, reduction of uranium, and mapping of two-dimensional flow fields around a model dipole flow borehole system to validate numerical models. Costs are low: LED excitation sources (< US 50), flow chambers (US 200) and detectors (although a complete scientific-grade CCD set-up costs around US$ 8000, robust datasets can be obtained using a commercial digital SLR camera) mean that set-ups can be flexible to meet changing experimental

  4. Mass transport processes in the southern Scotia Sea: Evidence of paleoearthquakes

    NASA Astrophysics Data System (ADS)

    Ruano, Patricia; Bohoyo, Fernando; Galindo-Zaldívar, Jesús; Pérez, Lara F.; Hernández-Molina, F. Javier; Maldonado, Andrés; García, Marga; Medialdea, Teresa

    2014-12-01

    The southern margin of the Scotia Sea hosts the convergent boundary between the Scotia and Antarctic plates where a number of small basins are situated. Mass transport deposits (MTDs) within two of these small basins, Dove and Scan basins, reveal the importance of seismicity, slope instabilities and depositional processes in their growth patterns. Swath-bathymetry and very high-resolution seismic data show that there are over 200 MTDs in these basins in the last 100 ky record. MTD characterizations are determined on the basis of their regional distribution, shape, apparent size and depth. Their sedimentary and tectonic implications are discussed, as well as the evidence of different triggering mechanisms in this region, which is characterized at present by moderate-to-high magnitude, shallow to intermediate earthquakes. MTDs are more abundant in the Dove Basin (with lenticular and wedge shapes), suggesting that this basin was affected by active tectonics to a greater degree than the Scan Basin. This finding is significant in the overall evolutionary context of the Scotia Sea region and Scotia-Antarctic plate geodynamics. Nevertheless, other factors -volcanic activity, vigorous bottom-currents, and/or higher sedimentation rates - must also be considered for the generation of MTDs in the Scan Basin, where a variety of processes generated more diverse MTD morphologies. Paleoseismological estimations of the repeated occurrence of wedge shaped MTDs in contact with fault scarps point to potential sources of large magnitude (Mw ~ 7.2-7.3) paleoearthquakes in several sites, in agreement with the present high magnitudes of regional seismicity. This study shows MTDs to be appropriate as paleoearthquake indicators in active tectonic settings. The distribution of MTDs in the southern Scotia Sea has important implications for geodynamic and geohazard research. They may prove to be unmistakable stratigraphic markers for future basin analysis.

  5. Acceleration and transport processes - Verification and observations. [of particles in interstellar medium

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.

    1983-01-01

    The general problem of diffusive transport and acceleration of energetic charged particles is considered. The transport of solar-flare particles, solar modulation of galactic cosmic rays and shock acceleration processes on the solar wind are examined and observational tests are summarized. It is concluded that the basic diffusive transport equation is a useful approximation in situations like the solar wind, where turbulent scattering by magnetic irregularities is sufficient to maintain near isotropy. The application of this equation to the interstellar medium andd other, more distant astrophysical regimes is then discussed and implications for gamma-ray astrophysics are outlined. Finally the evidence for interstellar turbulence is reviewed and its consequences briefly discussed.

  6. Transport processes and mutual interactions of three bacterial strains in saturated porous media

    NASA Astrophysics Data System (ADS)

    Stumpp, Christine; Lawrence, John R.; Hendry, M. Jim; Maloszewski, Pitor

    2010-05-01

    Transport processes of the bacterial strains Klebsiella oxytoca, Burkholderia cepacia G4PR-1 and Pseudomonas sp #5 were investigated in saturated column experiments to study the differences in transport characteristics and the mutual interactions of these strains during transport. Soil column experiments (114 mm long x 33 mm in diameter) were conducted with constant water velocities (3.9-5.7 cm/h) through a medium to coarse grained silica sand. All experiments were performed in freshly packed columns in quadruplicate. Chloride was used as tracer to determine the mean transit time, dispersivity and flow rate. It was injected as a pulse into the columns together with the bacterial strains suspended in artificial groundwater medium. In the first setup, each strain was investigated alone. In the second setup, transport processes were performed injecting two strains simultaneously. Finally, the transport characteristics were studied in successive experiments when one bacterium was resident on the sand grains prior to the introduction of the second strain. In all experiments the peak C/Co bacterial concentrations were attenuated with respect to the conservative tracer chloride and a well defined tailing was observed. A one dimensional mathematical model for advective-dispersive transport that accounts for irreversible and reversible sorption was used to analyze the bacterial breakthrough curves and tailing patterns. It was shown that the sorption parameters were different for the three strains that can be explained by the properties of the bacteria. For the species Klebsiella oxytoca and Burkholderia cepacia G4PR-the transport parameters were mostly in the same range independent of the experimental setup. However, Pseudomonas sp #5, which is a motile bacterium, showed differences in the breakthrough curves and sorption parameters during the experiments. The simultaneous and successive experiments indicated an influence on the reversible sorption processes when another

  7. Modeling the coupled mechanics, transport, and growth processes in collagen tissues.

    SciTech Connect

    Holdych, David J.; Nguyen, Thao D.; Klein, Patrick A.; in't Veld, Pieter J.; Stevens, Mark Jackson

    2006-11-01

    The purpose of this project is to develop tools to model and simulate the processes of self-assembly and growth in biological systems from the molecular to the continuum length scales. The model biological system chosen for the study is the tendon fiber which is composed mainly of Type I collagen fibrils. The macroscopic processes of self-assembly and growth at the fiber scale arise from microscopic processes at the fibrillar and molecular length scales. At these nano-scopic length scales, we employed molecular modeling and simulation method to characterize the mechanical behavior and stability of the collagen triple helix and the collagen fibril. To obtain the physical parameters governing mass transport in the tendon fiber we performed direct numerical simulations of fluid flow and solute transport through an idealized fibrillar microstructure. At the continuum scale, we developed a mixture theory approach for modeling the coupled processes of mechanical deformation, transport, and species inter-conversion involved in growth. In the mixture theory approach, the microstructure of the tissue is represented by the species concentration and transport and material parameters, obtained from fibril and molecular scale calculations, while the mechanical deformation, transport, and growth processes are governed by balance laws and constitutive relations developed within a thermodynamically consistent framework.

  8. Littoral transport rates in the Santa Barbara Littoral Cell: a process-based model analysis

    USGS Publications Warehouse

    Elias, E. P. L.; Barnard, Patrick L.; Brocatus, John

    2009-01-01

    Identification of the sediment transport patterns and pathways is essential for sustainable coastal zone management of the heavily modified coastline of Santa Barbara and Ventura County (California, USA). A process-based model application, based on Delft3D Online Morphology, is used to investigate the littoral transport potential along the Santa Barbara Littoral Cell (between Point Conception and Mugu Canyon). An advanced optimalization procedure is applied to enable annual sediment transport computations by reducing the ocean wave climate in 10 wave height - direction classes. Modeled littoral transport rates compare well with observed dredging volumes, and erosion or sedimentation hotspots coincide with the modeled divergence and convergence of the transport gradients. Sediment transport rates are strongly dependent on the alongshore variation in wave height due to wave sheltering, diffraction and focusing by the Northern Channel Islands, and the local orientation of the geologically-controlled coastline. Local transport gradients exceed the net eastward littoral transport, and are considered a primary driver for hot-spot erosion.

  9. The importance of gradients in particle activity during sediment transport: Insights from a probabilistic description of particle motions

    NASA Astrophysics Data System (ADS)

    Furbish, D. J.

    2009-04-01

    Sediment particles transported by rainsplash, by bioturbation, and as bedload in turbulent flows, undergo motions that are quasi-random in magnitude and direction. Moreover, these motions characteristically are intermittent, in that particles are mostly at rest most of the time, and heterogeneous, in that the volumetric or areal concentration of particles in motion at any instant is spatially patchy. These particle motions can be formulated as a stochastic processes involving both advective and dispersive parts. By taking into account the intermittent activity of particles, and separating this activity from the physics of motion in the parametric description of transport, the formulation indicates that gradients in particle activity can have a key role in transport. The formulation illustrates, for example, how the growth of soil mounds beneath desert shrubs involves differential rainsplash that initially causes more grains to be splashed inward beneath protective shrub canopies than outward. This ‘harvesting' of nearby soil material, including nutrients, means that shrubs locally participate in regulating the rate sediment transport down a hillslope. With soil bioturbation, spatial variations in the disturbance frequency strongly influence the mixing of soil constituents, including distinct particle fractions (such as specific size or mineral fractions, seeds, or debitage), or elements and compounds adsorbed to particles. The formulation also provides a probabilistic version of the Exner equation. During bedload transport, gradients in particle activity, through both advective and dispersive effects, may contribute importantly to the local divergence of the particle flux, thereby influencing initial bedform growth.

  10. RAFT: A simulator for ReActive Flow and Transport of groundwater contaminants

    SciTech Connect

    Chilakapati, A

    1995-07-01

    This report documents the use of the simulator RAFT for the ReActive flow and Transport of groundwater contaminants. RAFT can be used as a predictive tool in the design and analysis of laboratory and field experiments or it can be used for the estimation of model/process parameters from experiments. RAFT simulates the reactive transport of groundwater contaminants in one, two-, or three-dimensions and it can model user specified source/link configurations and arbitrary injection strategies. A suite of solvers for transport, reactions and regression are employed so that a combination of numerical methods best suited for a problem can be chosen. User specified coupled equilibrium and kinetic reaction systems can be incorporated into RAFT. RAFT is integrated with a symbolic computational language MAPLE, to automate code generation for arbitrary reaction systems. RAFT is expected to be used as a simulator for engineering design for field experiments in groundwater remediation including bioremediation, reactive barriers and redox manipulation. As an integrated tool with both the predictive ability and the ability to analyze experimental data, RAFT can help in the development of remediation technologies, from laboratory to field.

  11. Low Activity Waste Feed Process Control Strategy

    SciTech Connect

    STAEHR, T.W.

    2000-06-14

    The primary purpose of this document is to describe the overall process control strategy for monitoring and controlling the functions associated with the Phase 1B high-level waste feed delivery. This document provides the basis for process monitoring and control functions and requirements needed throughput the double-shell tank system during Phase 1 high-level waste feed delivery. This document is intended to be used by (1) the developers of the future Process Control Plan and (2) the developers of the monitoring and control system.

  12. Role of tryptophan-388 of GLUT1 glucose transporter in glucose-transport activity and photoaffinity-labelling with forskolin.

    PubMed Central

    Katagiri, H; Asano, T; Ishihara, H; Lin, J L; Inukai, K; Shanahan, M F; Tsukuda, K; Kikuchi, M; Yazaki, Y; Oka, Y

    1993-01-01

    GLUT1 glucose-transporter cDNA was modified to substitute leucine for Trp-388 and transfected into Chinese hamster ovary cells using the expression vector termed pMTHneo. This tryptophan residue is conserved among most of the facilitative glucose-transporter isoforms and has been proposed to be the photolabelling site of forskolin, a competitive inhibitor of glucose transport. In addition, this residue is located on membrane-spanning helix 10 which is suggested to contain the dynamic segment of the transporter. The mutated glucose transporter was expressed and inserted into the plasma membrane in a fashion similar to the wild-type. Unexpectedly, this mutation did not abolish photolabelling with forskolin. However, the mutation induced a marked decrease in 2-deoxyglucose uptake with a 4-fold decrease in turnover number and a 1.25-fold increase in Km compared with the wild-type GLUT1. A similar decrease in zero-trans influx activity was also observed for 3-O-methylglucose. In contrast, no apparent decrease was observed in zero trans efflux activity for 3-O-methylglucose. The mutation decreased the turnover number of the glucose transporter in equilibrium exchange influx for 3-O-methylglucose by 33% without any change in Km. These results indicate that (1) Trp-388 is not the photolabelling site for forskolin, if we assume that the labelling occurs at a single site and (2) Trp-388 is more likely to be involved in interconversion between the inward-facing and outward-facing conformers of GLUT1 than binding of glucose, and thus, substitution of leucine for Trp-388 in this dynamic segment would decrease the rate of alternating conformation, which would preferentially affect the influx activity. Images Figure 1 Figure 2 PMID:8489512

  13. A vadose zone Transport Processes Investigation within the glacial till at the Fernald Environmental Management Project.

    SciTech Connect

    Schwing, J.; Roepke, Craig Senninger; Brainard, James Robert; Glass, Robert John, Jr.; Mann, Michael J. A.; Holt, Robert M.; Kriel, Kelly

    2007-08-01

    This report describes a model Transport Processes Investigation (TPI) where field-scale vadose zone flow and transport processes are identified and verified through a systematic field investigation at a contaminated DOE site. The objective of the TPI is to help with formulating accurate conceptual models and aid in implementing rational and cost effective site specific characterization strategies at contaminated sites with diverse hydrogeologic settings. Central to the TPI are Transport Processes Characterization (TPC) tests that incorporate field surveys and large-scale infiltration experiments. Hypotheses are formulated based on observed pedogenic and hydrogeologic features as well as information provided by literature searches. The field and literature information is then used to optimize the design of one or more infiltration experiments to field test the hypothesis. Findings from the field surveys and infiltration experiments are then synthesized to formulate accurate flow and transport conceptual models. Here we document a TPI implemented in the glacial till vadose zone at the Fernald Environmental Management Project (FEMP) in Fernald, Ohio, a US Department of Energy (DOE) uranium processing site. As a result of this TPI, the flow and transport mechanisms were identified through visualization of dye stain within extensive macro pore and fracture networks which provided the means for the infiltrate to bypass potential aquatards. Such mechanisms are not addressed in current vadose zone modeling and are generally missed by classical characterization methods.

  14. Borreliacidal activity of Borrelia metal transporter A (BmtA) binding small molecules by manganese transport inhibition.

    PubMed

    Wagh, Dhananjay; Pothineni, Venkata Raveendra; Inayathullah, Mohammed; Liu, Song; Kim, Kwang-Min; Rajadas, Jayakumar

    2015-01-01

    Borrelia burgdorferi, the causative agent of Lyme disease, utilizes manganese (Mn) for its various metabolic needs. We hypothesized that blocking Mn transporter could be a possible approach to inhibit metabolic activity of this pathogen and eliminate the infection. We used a combination of in silico protein structure prediction together with molecular docking to target the Borrelia metal transporter A (BmtA), a single known Mn transporter in Borrelia and screened libraries of FDA approved compounds that could potentially bind to the predicted BmtA structure with high affinity. Tricyclic antihistamines such as loratadine, desloratadine, and 3-hydroxydesloratadine as well as yohimbine and tadalafil demonstrated a tight binding to the in silico folded BmtA transporter. We, then, tested borreliacidal activity and dose response of the shortlisted compounds from this screen using a series of in vitro assays. Amongst the probed compounds, desloratadine exhibited potent borreliacidal activity in vitro at and above 78 μg/mL (250 μM). Borrelia treated with lethal doses of desloratadine exhibited a significant loss of intracellular Mn specifically and a severe structural damage to the bacterial cell wall. Our results support the possibility of developing a novel, targeted therapy to treat Lyme disease by targeting specific metabolic needs of Borrelia. PMID:25709405

  15. Implementation of polarization processes in a charge transport model applied on poly(ethylene naphthalate) films

    NASA Astrophysics Data System (ADS)

    Hoang, M.-Q.; Le Roy, S.; Boudou, L.; Teyssedre, G.

    2016-06-01

    One of the difficulties in unravelling transport processes in electrically insulating materials is the fact that the response, notably charging current transients, can have mixed contributions from orientation polarization and from space charge processes. This work aims at identifying and characterizing the polarization processes in a polar polymer in the time and frequency-domains and to implement the contribution of the polarization into a charge transport model. To do so, Alternate Polarization Current (APC) and Dielectric Spectroscopy measurements have been performed on poly(ethylene naphthalene 2,6-dicarboxylate) (PEN), an aromatic polar polymer, providing information on polarization mechanisms in the time- and frequency-domain, respectively. In the frequency-domain, PEN exhibits 3 relaxation processes termed β, β* (sub-glass transitions), and α relaxations (glass transition) in increasing order of temperature. Conduction was also detected at high temperatures. Dielectric responses were treated using a simplified version of the Havriliak-Negami model (Cole-Cole (CC) model), using 3 parameters per relaxation process, these parameters being temperature dependent. The time dependent polarization obtained from the CC model is then added to a charge transport model. Simulated currents issued from the transport model implemented with the polarization are compared with the measured APCs, showing a good consistency between experiments and simulations in a situation where the response comes essentially from dipolar processes.

  16. Perfluoroalkyl Acid Concentrations in Blood Samples Subjected to Transportation and Processing Delay

    PubMed Central

    Bach, Cathrine Carlsen; Henriksen, Tine Brink; Bossi, Rossana; Bech, Bodil Hammer; Fuglsang, Jens; Olsen, Jørn; Nohr, Ellen Aagaard

    2015-01-01

    Background In studies of perfluoroalkyl acids, the validity and comparability of measured concentrations may be affected by differences in the handling of biospecimens. We aimed to investigate whether measured plasma levels of perfluoroalkyl acids differed between blood samples subjected to delay and transportation prior to processing and samples with immediate processing and freezing. Methods Pregnant women recruited at Aarhus University Hospital, Denmark, (n = 88) provided paired blood samples. For each pair of samples, one was immediately processed and plasma was frozen, and the other was delayed and transported as whole blood before processing and freezing of plasma (similar to the Danish National Birth Cohort). We measured 12 perfluoroalkyl acids and present results for compounds with more than 50% of samples above the lower limit of quantification. Results For samples taken in the winter, relative differences between the paired samples ranged between -77 and +38% for individual perfluoroalkyl acids. In most cases concentrations were lower in the delayed and transported samples, e.g. the relative difference was -29% (95% confidence interval -30; -27) for perfluorooctane sulfonate. For perfluorooctanoate there was no difference between the two setups [corresponding estimate 1% (0, 3)]. Differences were negligible in the summer for all compounds. Conclusions Transport of blood samples and processing delay, similar to conditions applied in some large, population-based studies, may affect measured perfluoroalkyl acid concentrations, mainly when outdoor temperatures are low. Attention to processing conditions is needed in studies of perfluoroalkyl acid exposure in humans. PMID:26356420

  17. Interactions of solutes and streambed sediment. 2. A dynamic analysis of coupled hydrologic and chemical processes that determine solute transport.

    USGS Publications Warehouse

    Bencala, K.E.

    1984-01-01

    Solute transport in streams is determined by the interaction of physical and chemical processes. Data from an injection experiment for chloride and several cations indicate significant influence of solute-streambed processes on transport in a mountain stream. These data are interpreted in terms of transient storage processes for all tracers and sorption processes for the cations. Process parameter values are estimated with simulations based on coupled quasi-two-dimensional transport and first-order mass transfer sorption. Comparative simulations demonstrate the relative roles of the physical and chemical processes in determining solute transport. -from Author

  18. Applications of Electro-Osmotic Transport in the Processing of Textiles

    SciTech Connect

    Cooper, J.F.; Krueger, R.; Hopper, R.; Cherepy, N.

    1999-11-29

    We report development of a pilot process for the industrial rinsing of fabrics. This process combines hydraulic (pressure-driven) transport with electro-osmotic transport. It reduces the total amount of water required in certain rinsing operations by a factor of about five. Cotton exhibits an electro-osmotic transport coefficient of about 6 x 10{sup -9} m{sup 2}/s-V resulting from a partial ionization of hydroxyl groups on the cellulose polymer substrate. This process applies a field transverse to the fabric to effect the movement of water in the spaces between the 10 {micro}m cotton fibers which constitute the yam. The field strength is adjusted so that the induced electro-osmotic flux is comparable to a pressure-driven flux, which moves preferentially in the more open channels between the yams. For a fixed current density, solution conductivity and electro-osmotic transport vary inversely. The process is most practical for removal of liquids of relatively low conductivity (<500 {micro}S/cm). For removal of solutions of conductivity greater than 1200 {micro}S/cm, the rate of electro-osmotic flow may be too low to benefit the rinsing process if current densities are restricted to practical levels of about 30 mA/cm{sup 2}. Electra-osmotic transport may have important applications in wet processing of extremely fine textiles, such as micro fiber fabrics. In addition to rinsing, electro-osmotic transport may also be used to speed the penetration of chemicals and dyestuffs that are applied to the surface of wet textiles.

  19. Physical Activity Associated with Public Transport Use—A Review and Modelling of Potential Benefits

    PubMed Central

    Rissel, Chris; Curac, Nada; Greenaway, Mark; Bauman, Adrian

    2012-01-01

    Active travel, particularly walking and cycling, has been recommended because of the health benefits associated with increased physical activity. Use of public transport generally involves some walking to bus stops or train stations. This paper is a systematic review of how much time is spent in physical activity among adults using public transport. It also explores the potential effect on the population level of physical activity if inactive adults in NSW, Australia, increased their walking through increased use of public transport. Of 1,733 articles, 27 met the search criteria, and nine reported on absolute measures of physical activity associated with public transport. A further 18 papers reported on factors associated with physical activity as part of public transport use. A range of 8–33 additional minutes of walking was identified from this systematic search as being attributable to public transport use. Using “bootstrapping” statistical modelling, if 20% of all inactive adults increased their walking by only 16 minutes a day for five days a week, we predict there would be a substantial 6.97% increase in the proportion of the adult population considered “sufficiently active”. More minutes walked per day, or a greater uptake of public transport by inactive adults would likely lead to significantly greater increases in the adult population considered sufficiently active. PMID:22851954

  20. Na+-K+-activated adenosine triphosphatase and intestinal electrolyte transport. Effect of adrenal steroids.

    PubMed Central

    Charney, A N; Kinsey, M D; Myers, L; Gainnella, R A; Gots, R E

    1975-01-01

    Sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) is associated with electrolyte transport in many tissues. To help delineate its role in intestinal transport, changes in rat intestinal electrolyte and water transport induced by injecting methylprednisolone acetate 3 mg/100 g or deoxycorticosterone acetate (DOCA) 0.5 mg/100 g per day for 3 days were correlated with changes in Na-K-ATPase activity. Methylprednisolone increased sodium and water absorption, potassium secretion, transmural potential difference, and Na-K-ATPase activity in the jejunum, ileum, and colon. Examination of isolated epithelial cells demonstrated that the jejunal and ileal increase in Na-K-ATPase occurred in both the villus tip and crypermeability, Mg-ATPase, and adenylate cyclase activities were unchanged by methylprednisolone. DOCA increased sodium and water absorption, potassium secretion, transmural potential difference, and Na-K-ATPase activity in the colon alone. Colonic Mg-ATPase and adenylate cyclase activities were unaffected. Jejunal and ileal enzyme activity, electrolyte transport, and permeability were unchanged by DOCA. Methylprednisolone and DOCA were not additive in their effect on colonic Na-K-ATPase activity. Methylprednisolone and DOCA increased electrolyte and water transport and Na-K-ATPase activity concomitantly in specific segments of small intestine and colon. These data are consistent with an important role for Na-K-ATPase in intestinal electrolyte and water transport. PMID:125764

  1. Polarization fluctuation dominated electrical transport processes of polymer-based ferroelectric field effect transistors

    NASA Astrophysics Data System (ADS)

    Senanayak, Satyaprasad P.; Guha, S.; Narayan, K. S.

    2012-03-01

    Ferroelectric field effect transistors (FE-FETs) consisting of tunable dielectric layers are utilized to investigate interfacial transport processes. Large changes in the dielectric constant as a function of temperature are observed in FE-FETs in conjunction with the ferroelectric to paraelectric transition. The devices offer a test bed to evaluate specific effects of polarization on the electrical processes. FE-FETs have dominant contributions from polarization fluctuation rather than static dipolar disorder prevalent in high k paraelectric dielectric-based FETs. Additionally, photo-excitation measurements in the depletion mode reveal clear features in the FET response at different temperatures, indicative of different transport regimes.

  2. Activity dependent internalization of the glutamate transporter GLT-1 mediated by β-arrestin 1 and ubiquitination.

    PubMed

    Ibáñez, Ignacio; Díez-Guerra, F Javier; Giménez, Cecilio; Zafra, Francisco

    2016-08-01

    GLT-1 is the main glutamate transporter in the brain and undergoes trafficking processes that control its concentration on the cell surface thereby shaping glutamatergic neurotransmission. We have investigated how the traffic of GLT-1 is regulated by transporter activity. We report that internalization of GLT-1 from the cell surface is accelerated by transportable substrates like glutamate or aspartate, as well as by the transportable inhibitor L-trans-2,4-PDC, but not by the non-substrate inhibitor WAY 213613 in primary mixed cultures and in transiently transfected HEK293 cells. Analysis of the mechanism of endocytosis in HEK293 cells revealed that glutamate promoted the association with the transporter of the adaptor protein β-arrestin and the ubiquitin ligase Nedd4-2. The addition of glutamate is accompanied by an increase in the transporter ubiquitination, and the internalization is suppressed by an ubiquitination inhibitor (PYR41), and in a mutant defective in C-terminal lysines. The glutamate triggered endocytosis was also suppressed by siRNA for β-arrestin. This regulatory mechanism might be relevant in controlling the amount of transporter on the cell surface in conditions such as ischemia or traumatic brain injury, where extracellular concentrations of glutamate are persistently elevated. PMID:27044663

  3. Transportation.

    ERIC Educational Resources Information Center

    Crank, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with transportation and energy use. Its objective is for the student to be able to discuss the implication of energy usage as it applies to the area of transportation. Some topics covered are efficiencies of various transportation…

  4. Active geologic processes in Barrow Canyon, northeast Chukchi Sea

    USGS Publications Warehouse

    Eittreim, S.; Grantz, A.; Greenberg, J.

    1982-01-01

    Circulation patterns on the shelf and at the shelf break appear to dominate the Barrow Canyon system. The canyon's shelf portion underlies and is maintained by the Alaska Coastal Current (A.C.C.), which flows northeastward along the coast toward the northeast corner of the broad Chukchi Sea. Offshelf and onshelf advective processes are indicated by oceanographic measurements of other workers. These advective processes may play an important role in the production of bedforms that are found near the canyon head as well as in processes of erosion or non-deposition in the deeper canyon itself. Coarse sediments recovered from the canyon axis at 400 to 570 m indicate that there is presently significant flow along the canyon. The canyon hooks left at a point north of Point Barrow where the A.C.C. loses its coastal constriction. The left hook, as well as preferential west-wall erosion, continues down to the abyssal plain of the Canada Basin at 3800 m. A possible explanation for the preferential west-wall erosion along the canyon, at least for the upper few hundred meters, is that the occasional upwelling events, which cause nutrient-rich water to flow along the west wall would in turn cause larger populations of burrowing organisms to live there than on the east wall, and that these organisms cause high rates of bioerosion. This hypothesis assumes that the dominant factor in the canyon's erosion is biological activity, not current velocity. Sedimentary bedforms consisting of waves and furrows are formed in soft mud in a region on the shelf west of the canyon head; their presence there perhaps reflects: (a) the supply of fine suspended sediments delivered by the A.C.C. from sources to the south, probably the Yukon and other rivers draining northwestern Alaska; and (b) the westward transport of these suspended sediments by the prevailing Beaufort Gyre which flows along the outer shelf. ?? 1982.

  5. Laboratory Activities for Developing Process Skills.

    ERIC Educational Resources Information Center

    Institute for Services to Education, Inc., Washington, DC.

    This workbook contains laboratory exercises designed for use in a college introductory biology course. Each exercise helps the student develop a basic science skill. The exercises are arranged in a hierarchical sequence suggesting the scientific method. Each skill facilitates the development of succeeding ones. Activities include Use of the…

  6. Colloid release and transport processes in natural and model porous media

    SciTech Connect

    Roy, S.B.; Dzombak, D.A.

    1995-12-01

    Colloidal particles present in porous media may be released and transported over significant distances when contacted with water at low ionic strength. An understanding of this process is of environmental interest because suspended colloidal particles in groundwater may enhance the subsurface transport of contaminants that are sorbed on their surfaces. This research focused on the processes of colloid release and transport in natural porous media of interest in contaminant transport, i.e., high permeability materials with low fines contents. Our objective in this study was to examine the mechanisms of colloid release and transport in a natural sand, and two model systems: latex particles attached on glass beads, and kaolinite particles attached on glass beads. For the appropriate electrolyte conditions, the release of attached colloids from all three porous media was found to be substantial. The total amount of colloids released depended upon the electrolyte composition and concentration. Column effluent data could be described with an advective-dispersive transport equation for colloidal particles with first-order terms for colloid release and deposition rates, by changing the mass of colloids available for release at each electrolyte concentrations.

  7. Processes and controls of ditch erosion and suspended sediment transport in drained peatland forests

    NASA Astrophysics Data System (ADS)

    Tuukkanen, Tapio; Stenberg, Leena; Marttila, Hannu; Finér, Leena; Piirainen, Sirpa; Koivusalo, Harri; Kløve, Bjørn

    2016-04-01

    Drainage and periodic ditch cleaning are needed in peatland forests to allow adequate tree growth. The downside is that these practices usually increase erosion and transport of organic and inorganic matter to downstream waterbodies. In this study, our aim was to assess the role of hydrological factors and ditch-level bed and bank erosion processes in controlling suspended sediment (SS) transport in peatland forests after ditch cleaning. To do this, a 113 ha catchment and a nested sub-catchment (5.2 ha) in eastern Finland were instrumented for continuous hydrological and SS concentration (turbidity) measurements and for the detection of ditch bed and bank erosion with erosion pins. The impacts of ditch cleaning on instantaneous unit hydrographs were also assessed against two reference catchments. The results suggested that, in small intensively drained catchments, SS transport is likely to be limited by the availability of easily erodible sediment in the ditch network, and that ditch cleaning operations as well as preparatory bank erosion processes such as peat desiccation and frost action can be important in producing erodible sediment for transport. Detachment of soil particle from ditch banks by raindrop impact can also be an important factor explaining variations in SS concentrations in small catchments. In larger drainage areas, peak runoff characteristics may play a more dominant role in SS transport. The results give new insights into the dynamics of sediment transport in drained peatland catchments, which can be useful, for example, for planning and implementation of water conservation measures.

  8. Trace and major element pollution originating from coal ash suspension and transport processes.

    PubMed

    Popovic, A; Djordjevic, D; Polic, P

    2001-04-01

    Coal ash obtained by coal combustion in the "Nikola Tesla A" power plant in Obrenovac, near Belgrade, Yugoslavia, is mixed with water of the Sava river and transported to the dump. In order to assess pollution caused by leaching of some minor and major elements during ash transport through the pipeline, two sets of samples (six samples each) were subjected to a modified sequential extraction. The first set consisted of coal ash samples taken immediately after combustion, while the second set was obtained by extraction with river water, imitating the processes that occur in the pipeline. Samples were extracted consecutively with distilled water and a 1 M solution of KCl, pH 7, and the differences in extractability were compared in order to predict potential pollution. Considering concentrations of seven trace elements as well as five major elements in extracts from a total of 12 samples, it can be concluded that lead and cadmium do not present an environmental threat during and immediately after ash transport to the dump. Portions of zinc, nickel and chromium are released during the ash transport, and arsenic and manganese are released continuously. Copper and iron do not present an environmental threat due to element leaching during and immediately after the coal ash suspension and transport. On the contrary, these elements, as well as chromium, become concentrated during coal ash transport. Adsorbed portions of calcium, magnesium and potassium are also leached during coal ash transport. PMID:11341293

  9. Policies related to active transport to and from school: a multisite case study.

    PubMed

    Eyler, Amy A; Brownson, Ross C; Doescher, Mark P; Evenson, Kelly R; Fesperman, Carrie E; Litt, Jill S; Pluto, Delores; Steinman, Lesley E; Terpstra, Jennifer L; Troped, Philip J; Schmid, Thomas L

    2008-12-01

    Active transportation to and from school (ATS) is a viable strategy to help increase physical activity among youth. ATS can be challenging because initiatives require transdisciplinary collaboration, are influenced by the built environment and are affected by numerous policies. The purpose of this study is to identify policies and factors that influence ATS initiatives. Nine elementary schools in seven states participated in this case study. Sixty-nine stakeholders were interviewed. The interviews were transcribed, coded and analyzed using a master thematic codebook. This study identified two distinct aspects of policies: 'influential factors' which are factors that might impact policies related to ATS and 'policy actions' which are policies reported by people involved in ATS initiatives that directly affected their success. Influential factors included sidewalks, crosswalks/crossing guards, funding, personal safety concerns, advocacy group involvement and others. Policy actions included policies on school speed zone, drop-off, no-transport zones, school siting, school start/dismissal time and school choice. Despite the diversity of the schools studied, similarities included influence of built environment, safety concerns, funding and transdisciplinary collaboration. Stakeholders need to work together to stimulate action and ensure successful initiatives. Influential factors appear to be important to this process. PMID:17956883

  10. Lateral transport of solutes in microfluidic channels using electrochemically generated gradients in redox-active surfactants.

    PubMed

    Liu, Xiaoyang; Abbott, Nicholas L

    2011-04-15

    We report principles for a continuous flow process that can separate solutes based on a driving force for selective transport that is generated by a lateral concentration gradient of a redox-active surfactant across a microfluidic channel. Microfluidic channels fabricated with gold electrodes lining each vertical wall were used to electrochemically generate concentration gradients of the redox-active surfactant 11-ferrocenylundecyl-trimethylammonium bromide (FTMA) in a direction perpendicular to the flow. The interactions of three solutes (a hydrophobic dye, 1-phenylazo-2-naphthylamine (yellow AB), an amphiphilic molecule, 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (BODIPY C(5)-HPC), and an organic salt, 1-methylpyridinium-3-sulfonate (MPS)) with the lateral gradients in surfactant/micelle concentration were shown to drive the formation of solute-specific concentration gradients. Two distinct physical mechanisms were identified to lead to the solute concentration gradients: solubilization of solutes by micelles and differential adsorption of the solutes onto the walls of the microchannels in the presence of the surfactant concentration gradient. These two mechanisms were used to demonstrate delipidation of a mixture of BODIPY C(5)-HPC (lipid) and MPS and purification of BODIPY C(5)-HPC from a mixture of BODIPY C(5)-HPC and yellow AB. Overall, the results of this study demonstrate that lateral concentration gradients of redox-active surfactants formed within microfluidic channels can be used to transport solutes across the microfluidic channels in a solute-dependent manner. The approach employs electrical potentials (<1 V) that are sufficiently small to avoid electrolysis of water, can be performed in solutions having high ionic strength (>0.1M), and offers the basis of continuous processes for the purification or separation of solutes in microscale systems. PMID:21446653

  11. The Green Revolution in Transportation. Resource Recovery. Technology Learning Activities.

    ERIC Educational Resources Information Center

    Technology Teacher, 1991

    1991-01-01

    These two learning activities provide context, objectives, list of materials, student activity, and evaluation criteria. The first involves an automotive class in developing a model alternative fueled vehicle, and the second involves the design of a useful recyclable product. (JOW)

  12. Gravity-Related Transport Process in Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehozeku, S. L.

    2000-01-01

    In the synthesis of epitaxial oxide films, reactive off-axis sputtering deposition techniques have demonstrated the advantages of fabricating high quality epitaxial films. Due to the collisions between the sputtered species and the residue gases, the kinetic energy of species was reduced and the transport of depositing species changed from a ballistic movement to a diffusive drift in which the transport species were almost thermalized. A gravity effect could appear in the transport process. Three transport regimes were observed when the growth pressures vary from 5 mTorr to 150 mTorr. Film growth rate, depositing orientations, crystal structure, surface morphology, and compositions were characterized. A gravity related phenomenon was revealed in film growth at the relative low growth pressures.

  13. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  14. INFLUENCE OF COUPLED PROCESSES ON CONTAMINANT FATE AND TRANSPORT IN SUBSURFACE ENVIRONMENTS

    SciTech Connect

    Jardine, Philip M

    2008-01-01

    The following chapter emphasizes subsurface environmental research investigations over the past 10 to 15 years that couple hydrological, geochemical, and biological processes as related to contaminant fate and transport. An attempt is made to focus on field-scale studies with possible reference to laboratory-scale endeavors. Much of the research discussed reflects investigations of the influence of coupled processes on the fate and transport of inorganic, radionuclide, and organic contaminants in subsurface environments as a result of natural processes or energy and weapons production endeavors that required waste disposal. The chapter provides on overview of the interaction between hydro-bio-geochemical processes in structured, heterogeneous subsurface environments and how these interactions control contaminant fate and transport, followed by experimental and numerical subsurface science research and case studies involving specific classes of inorganic and organic contaminants. Lastly, thought provoking insights are highlighted on why the study of subsurface coupled processes is paramount to understanding potential future contaminant fate and transport issues of global concern.

  15. Opposite-polarity motors activate one another to trigger cargo transport in live cells.

    PubMed

    Ally, Shabeen; Larson, Adam G; Barlan, Kari; Rice, Sarah E; Gelfand, Vladimir I

    2009-12-28

    Intracellular transport is typically bidirectional, consisting of a series of back and forth movements. Kinesin-1 and cytoplasmic dynein require each other for bidirectional transport of intracellular cargo along microtubules; i.e., inhibition or depletion of kinesin-1 abolishes dynein-driven cargo transport and vice versa. Using Drosophila melanogaster S2 cells, we demonstrate that replacement of endogenous kinesin-1 or dynein with an unrelated, peroxisome-targeted motor of the same directionality activates peroxisome transport in the opposite direction. However, motility-deficient versions of motors, which retain the ability to bind microtubules and hydrolyze adenosine triphosphate, do not activate peroxisome motility. Thus, any pair of opposite-polarity motors, provided they move along microtubules, can activate one another. These results demonstrate that mechanical interactions between opposite-polarity motors are necessary and sufficient for bidirectional organelle transport in live cells. PMID:20038680

  16. Opposite-polarity motors activate one another to trigger cargo transport in live cells

    PubMed Central

    Ally, Shabeen; Larson, Adam G.; Barlan, Kari; Rice, Sarah E.

    2009-01-01

    Intracellular transport is typically bidirectional, consisting of a series of back and forth movements. Kinesin-1 and cytoplasmic dynein require each other for bidirectional transport of intracellular cargo along microtubules; i.e., inhibition or depletion of kinesin-1 abolishes dynein-driven cargo transport and vice versa. Using Drosophila melanogaster S2 cells, we demonstrate that replacement of endogenous kinesin-1 or dynein with an unrelated, peroxisome-targeted motor of the same directionality activates peroxisome transport in the opposite direction. However, motility-deficient versions of motors, which retain the ability to bind microtubules and hydrolyze adenosine triphosphate, do not activate peroxisome motility. Thus, any pair of opposite-polarity motors, provided they move along microtubules, can activate one another. These results demonstrate that mechanical interactions between opposite-polarity motors are necessary and sufficient for bidirectional organelle transport in live cells. PMID:20038680

  17. Modelling the Active Hearing Process in Mosquitoes

    NASA Astrophysics Data System (ADS)

    Avitabile, Daniele; Homer, Martin; Jackson, Joe; Robert, Daniel; Champneys, Alan

    2011-11-01

    A simple microscopic mechanistic model is described of the active amplification within the Johnston's organ of the mosquito species Toxorhynchites brevipalpis. The model is based on the description of the antenna as a forced-damped oscillator coupled to a set of active threads (ensembles of scolopidia) that provide an impulsive force when they twitch. This twitching is in turn controlled by channels that are opened and closed if the antennal oscillation reaches a critical amplitude. The model matches both qualitatively and quantitatively with recent experiments. New results are presented using mathematical homogenization techniques to derive a mesoscopic model as a simple oscillator with nonlinear force and damping characteristics. It is shown how the results from this new model closely resemble those from the microscopic model as the number of threads approach physiologically correct values.

  18. A systematic review of interventions for promoting active transportation to school

    PubMed Central

    2011-01-01

    Background Active transportation to school is an important contributor to the total physical activity of children and adolescents. However, active school travel has declined over time, and interventions are needed to reverse this trend. The purpose of this paper is to review intervention studies related to active school transportation to guide future intervention research. Methods A systematic review was conducted to identify intervention studies of active transportation to school published in the scientific literature through January 2010. Five electronic databases and a manual search were conducted. Detailed information was extracted, including a quantitative assessment comparing the effect sizes, and a qualitative assessment using an established evaluation tool. Results We identified 14 interventions that focused on active transportation to school. These interventions mainly focused on primary school children in the United States, Australia, and the United Kingdom. Almost all the interventions used quasi-experimental designs (10/14), and most of the interventions reported a small effect size on active transportation (6/14). Conclusion More research with higher quality study designs and measures should be conducted to further evaluate interventions and to determine the most successful strategies for increasing active transportation to school. PMID:21320322

  19. Identification of an important motif that controls the activity and specificity of sugar transporters.

    PubMed

    Wang, Meng; Yu, Chenzhao; Zhao, Huimin

    2016-07-01

    Efficient glucose-xylose co-utilization is critical for economical biofuel production from lignocellulosic biomass. To enable glucose-xylose co-utilization, a highly active xylose specific transporter without glucose inhibition is desirable. However, our understanding of the structure-activity/specificity relationship of sugar transporters in general is limited, which hinders our ability to engineer xylose-specific transporters. In this study, via homology modeling and analysis of hexose sugar transporter HXT14 mutants, we identified a highly conserved YYX(T/P) motif that plays an important role in controlling the activity and specificity of sugar transporters. We demonstrated that mutating the two tyrosine residues of the motif to phenylalanine, respectively, improved glucose transport capacity across several different sugar transporters. Furthermore, we illustrated that by engineering the fourth position in the YYX(T/P) motif, the sugar specificity of transporters was significantly altered or even reversed towards xylose. Finally, using the engineered sugar transporter, genuine glucose-xylose co-fermentation was achieved. Biotechnol. Bioeng. 2016;113: 1460-1467. © 2016 Wiley Periodicals, Inc. PMID:26724683

  20. Alteration of human hepatic drug transporter activity and expression by cigarette smoke condensate.

    PubMed

    Sayyed, Katia; Vee, Marc Le; Abdel-Razzak, Ziad; Jouan, Elodie; Stieger, Bruno; Denizot, Claire; Parmentier, Yannick; Fardel, Olivier

    2016-07-01

    Smoking is well-known to impair pharmacokinetics, through inducing expression of drug metabolizing enzymes. In the present study, we demonstrated that cigarette smoke condensate (CSC) also alters activity and expression of hepatic drug transporters, which are now recognized as major actors of hepatobiliary elimination of drugs. CSC thus directly inhibited activities of sinusoidal transporters such as OATP1B1, OATP1B3, OCT1 and NTCP as well as those of canalicular transporters like P-glycoprotein, MRP2, BCRP and MATE1, in hepatic transporters-overexpressing cells. CSC similarly counteracted constitutive OATP, NTCP and OCT1 activities in human highly-differentiated hepatic HepaRG cells. In parallel, CSC induced expression of BCRP at both mRNA and protein level in HepaRG cells, whereas it concomitantly repressed mRNA expression of various transporters, including OATP1B1, OATP2B1, OAT2, NTCP, OCT1 and BSEP, and enhanced that of MRP4. Such changes in transporter gene expression were found to be highly correlated to those caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin, a reference activator of the aryl hydrocarbon receptor (AhR) pathway, and were counteracted, for some of them, by siRNA-mediated AhR silencing. This suggests that CSC alters hepatic drug transporter levels via activation of the AhR cascade. Importantly, drug transporter expression regulations as well as some transporter activity inhibitions occurred for a range of CSC concentrations similar to those required for inducing drug metabolizing enzymes and may therefore be hypothesized to be relevant for smokers. Taken together, these data established human hepatic transporters as targets of cigarette smoke, which could contribute to known alteration of pharmacokinetics and some liver adverse effects caused by smoking. PMID:27450509

  1. SIMPLIFIED INJECTION OF OXYGEN GAS INTO AN ACTIVATED SLUDGE PROCESS

    EPA Science Inventory

    The Las Virgenes Municipal Water District conducted a pilot investigation of the Simplox process at their Tapia Water Reclamation Facility in Calabasas, California. The Simplox process, developed by the Cosmodyne Division of Cordon International, involves covering an activated sl...

  2. Growth kinetics of physical vapor transport processes: Crystal growth of the optoelectronic material mercurous chloride

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Duval, W. M.

    1991-01-01

    Physical vapor transport processes were studied for the purpose of identifying the magnitude of convective effects on the crystal growth process. The effects of convection on crystal quality were were studied by varying the aspect ratio and those thermal conditions which ultimately affect thermal convection during physical vapor transport. An important outcome of the present study was the observation that the convection growth rate increased up to a certain value and then dropped to a constant value for high aspect ratios. This indicated that a very complex transport had occurred which could not be explained by linear stability theory. Better quality crystals grown at a low Rayleigh number confirmed that improved properties are possible in convectionless environments.

  3. A triple-continuum approach for modeling flow and transport processes in fractured rock.

    PubMed

    Wu, Yu-Shu; Liu, H H; Bodvarsson, G S

    2004-09-01

    This paper presents a triple-continuum conceptual model for simulating flow and transport processes in fractured rock. Field data collected from the unsaturated zone of Yucca Mountain, a repository site of high-level nuclear waste, show a large number of small-scale fractures. The effect of these small fractures has not been considered in previous modeling investigations within the context of a continuum approach. A new triple-continuum model (consisting of matrix, small-fracture, and large-fracture continua) has been developed to investigate the effect of these small fractures. This paper derives the model formulation and discusses the basic triple-continuum behavior of flow and transport processes under different conditions, using both analytical solutions and numerical approaches. The simulation results from the site-scale model of the unsaturated zone of Yucca Mountain indicate that these small fractures may have an important effect on radionuclide transport within the mountain. PMID:15336793

  4. Skylab and solar exploration. [chromosphere-corona structure, energy production and heat transport processes

    NASA Technical Reports Server (NTRS)

    Von Puttkamer, J.

    1973-01-01

    Review of some of the findings concerning solar structure, energy production, and heat transport obtained with the aid of the manned Skylab space station observatory launched on May 14, 1973. Among the topics discussed are the observation of thermonuclear fusion processes which cannot be simulated on earth, the observation of short-wave solar radiation not visible to observers on earth, and the investigation of energy-transport processes occurring in the photosphere, chromosphere, and corona. An apparent paradox is noted in that the cooler chromosphere is heating the hotter corona, seemingly in defiance of the second law of thermodynamics, thus suggesting that a nonthermal mechanism underlies the energy transport. Understanding of this nonthermal mechanism is regarded as an indispensable prerequisite for future development of plasma systems for terrestrial applications.

  5. Uav Data Processing for Rapid Mapping Activities

    NASA Astrophysics Data System (ADS)

    Tampubolon, W.; Reinhardt, W.

    2015-08-01

    During disaster and emergency situations, geospatial data plays an important role to serve as a framework for decision support system. As one component of basic geospatial data, large scale topographical maps are mandatory in order to enable geospatial analysis within quite a number of societal challenges. The increasing role of geo-information in disaster management nowadays consequently needs to include geospatial aspects on its analysis. Therefore different geospatial datasets can be combined in order to produce reliable geospatial analysis especially in the context of disaster preparedness and emergency response. A very well-known issue in this context is the fast delivery of geospatial relevant data which is expressed by the term "Rapid Mapping". Unmanned Aerial Vehicle (UAV) is the rising geospatial data platform nowadays that can be attractive for modelling and monitoring the disaster area with a low cost and timely acquisition in such critical period of time. Disaster-related object extraction is of special interest for many applications. In this paper, UAV-borne data has been used for supporting rapid mapping activities in combination with high resolution airborne Interferometric Synthetic Aperture Radar (IFSAR) data. A real disaster instance from 2013 in conjunction with Mount Sinabung eruption, Northern Sumatra, Indonesia, is used as the benchmark test for the rapid mapping activities presented in this paper. On this context, the reliable IFSAR dataset from airborne data acquisition in 2011 has been used as a comparable dataset for accuracy investigation and assessment purpose in 3 D reconstructions. After all, this paper presents a proper geo-referencing and feature extraction method of UAV data to support rapid mapping activities.

  6. Individual Public Transportation Accessibility is Positively Associated with Self-Reported Active Commuting

    PubMed Central

    Djurhuus, Sune; Hansen, Henning Sten; Aadahl, Mette; Glümer, Charlotte

    2014-01-01

    Background: Active commuters have lower risk of chronic disease. Understanding which of the, to some extent, modifiable characteristics of public transportation that facilitate its use is thus important in a public health perspective. The aim of the study was to examine the association between individual public transportation accessibility and self-reported active commuting, and whether the associations varied with commute distance, age, and gender. Methods: Twenty-eight thousand nine hundred twenty-eight commuters in The Capital Region of Denmark reported self-reported time spent either walking or cycling to work or study each day and the distance to work or study. Data were obtained from the Danish National Health Survey collected in February to April 2010. Individual accessibility by public transportation was calculated using a multi-modal network in a GIS. Multilevel logistic regression was used to analyze the association between accessibility, expressed as access area, and being an active commuter. Results: Public transport accessibility area based on all stops within walking and cycling distance was positively associated with being an active commuter. Distance to work, age, and gender modified the associations. Residing within 10 km commute distance and in areas of high accessibility was associated with being an active commuter and meeting the recommendations of physical activity. For the respondents above 29 years, individual public transportation accessibility was positively associated with being an active commuter. Women having high accessibility had significantly higher odds of being an active commuter compared to having a low accessibility. For men, the associations were insignificant. Conclusion: This study extends the knowledge about the driving forces of using public transportation for commuting by examining the individual public transportation accessibility. Findings suggest that transportation accessibility supports active commuting and planning

  7. Turbulence and Fluid Flow: Perspectives. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Simpson, James R.

    This module is part of a series on Physical Processes in Terrestrial and Aquatic Ecosystems. The materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process.…

  8. Low band gap polymeric solar cells using solution-processable copper iodide as hole transporting layer

    NASA Astrophysics Data System (ADS)

    Chaudhary, Neeraj; Kesari, J. P.; Chaudhary, Rajiv; Patra, Asit

    2016-08-01

    In the present work, we have shown the performance of solution-processable copper iodide (CuI) as an alternative hole transporting layer (HTL) for polymeric solar cells. Optical spectra of the CuI thin film reveal highly transparent and practically no absorption in the range vis-NIR region (450-1110 nm). X-ray diffraction (XRD) patterns of CuI exhibits as a p-type semiconductor as well as crystalline nature. The photovoltaic devices were fabricated using PCDTBT and PTB7 as donor materials blended with PC71BM as an acceptor material. The power conversion efficiencies (PCEs) based on CuI as an HTL have been achieved to up to 3.04% and 4.48% for PCDTBT and PTB7 based donor materials respectively with a configuration based on ITO/CuI(40 nm)/active layer (60 nm)/Al (120 nm). This study clearly indicated that the devices made with CuI as an HTL showed superior performance than the device fabricated from PEDOT:PSS layer as an HTL. Morphological characterization of the HTL using scanning electron microscopy (SEM) and atomic force microscope (AFM) were carried for better understanding.

  9. Industrial Arts Education Competency Catalogs for Communication Technology, Materials and Processes Technology, Power and Transportation Technology.

    ERIC Educational Resources Information Center

    Dugger, William E.; And Others

    Three competency catalogs of tasks for industrial arts programs are presented. These include catalogs in Communications Technology, Materials and Processes Technology, and Power and Transportation Technology. The purpose of each catalog is to establish a basis for program content selection and criterion levels from which one may measure to see if…

  10. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... degree of specificity required in the transportation plan and the specific travel network assumed for air quality modeling do not preclude the consideration of alternatives in the NEPA process or other project... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DETERMINING CONFORMITY OF FEDERAL...

  11. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... specificity required in the transportation plan and the specific travel network assumed for air quality modeling do not preclude the consideration of alternatives in the NEPA process or other project development... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DETERMINING CONFORMITY OF FEDERAL ACTIONS TO STATE...

  12. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... degree of specificity required in the transportation plan and the specific travel network assumed for air quality modeling do not preclude the consideration of alternatives in the NEPA process or other project... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DETERMINING CONFORMITY OF FEDERAL...

  13. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... degree of specificity required in the transportation plan and the specific travel network assumed for air quality modeling do not preclude the consideration of alternatives in the NEPA process or other project... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DETERMINING CONFORMITY OF FEDERAL...

  14. Clustering of a kinesin-14 motor enables processive retrograde microtubule-based transport in plants

    PubMed Central

    Jonsson, Erik; Yamada, Moé; Vale, Ronald D.; Goshima, Gohta

    2015-01-01

    The molecular motors kinesin and dynein drive bidirectional motility along microtubules (MTs) in most eukaryotic cells. Land plants, however, are a notable exception, because they contain a large number of kinesins but lack cytoplasmic dynein, the foremost processive retrograde transporter. It remains unclear how plants achieve retrograde cargo transport without dynein. Here, we have analysed the motility of the six members of minus-end-directed kinesin-14 motors in the moss Physcomitrella patens and found that none are processive as native dimers. However, when artificially clustered into as little as dimer of dimers, the type-VI kinesin-14 (a homologue of Arabidopsis KCBP (kinesin-like calmodulin binding protein)) exhibited highly processive and fast motility (up to 0.6 μm s−1). Multiple kin14-VI dimers attached to liposomes also induced transport of this membrane cargo over several microns. Consistent with these results, in vivo observations of green fluorescent protein-tagged kin14-VI in moss cells revealed fluorescent punctae that moved processively towards the minus-ends of the cytoplasmic MTs. These data suggest that clustering of a kinesin-14 motor serves as a dynein-independent mechanism for retrograde transport in plants. PMID:26322239

  15. Coupled transport processes in semipermeable media. Part 2: Numerical method and results

    NASA Astrophysics Data System (ADS)

    Jacobsen, Janet S.; Carnahan, Chalon L.

    1990-04-01

    A numerical simulator has been developed to investigate the effects of coupled processes on heat and mass transport in semipermeable media. The governing equations on which the simulator is based were derived using the thermodynamics of irreversible processes. The equations are nonlinear and have been solved numerically using the n-dimensional Newton's method. As an example of an application, the numerical simulator has been used to investigate heat and solute transport in the vicinity of a heat source buried in a saturated clay-like medium, in part to study solute transport in bentonite packing material surrounding a nuclear waste canister. The coupled processes considered were thermal filtration, thermal osmosis, chemical osmosis and ultrafiltration. In the simulations, heat transport by coupled processes was negligible compared to heat conduction, but pressure and solute migration were affected. Solute migration was retarded relative to the uncoupled case when only chemical osmosis was considered. When both chemical osmosis and thermal osmosis were included, solute migration was enhanced.

  16. Symposium on intermediate-range atmospheric-transport processes and technology assessment. [Lead Abstract

    SciTech Connect

    Not Available

    1981-10-01

    Separate abstracts were prepared for the 47 papers in this proceedings. The purpose of this meeting was to assess the state of the art of modeling atmospheric transport processes 10 to 100 km downwind of point and area sources of pollution. (KRM)

  17. Insight into sediment transport processes on saline rangeland hillslopes using three-dimensional soil microtoprgraphy changes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hillslope runoff and soil erosion processes play a vital role on rangeland ecosystem sustainability due to their control on resource mobility but they also have significant implications in off-site resource transport. In general, physically-based soil erosion models such as RHEM divide erosion and ...

  18. IRIP, a New Ischemia/Reperfusion-Inducible Protein That Participates in the Regulation of Transporter Activity

    PubMed Central

    Jiang, Wei; Prokopenko, Olga; Wong, Lawrence; Inouye, Masayori; Mirochnitchenko, Oleg

    2005-01-01

    We report the identification and characterization of a new ischemia/reperfusion-inducible protein (IRIP), which belongs to the SUA5/YrdC/YciO protein family. IRIP cDNA was isolated in a differential display analysis of an ischemia/reperfusion-treated kidney RNA sample. Mouse IRIP mRNA was expressed in all tissues tested, the highest level being in the testis, secretory, and endocrine organs. Besides ischemia/reperfusion, endotoxemia also activated the expression of IRIP in the liver, lung, and spleen. The transporter regulator RS1 was identified as an IRIP-interacting protein in yeast two-hybrid screening. The interaction between IRIP and RS1 was further confirmed in coimmunoprecipitation assays. A possible role of IRIP in regulating transporter activity was subsequently investigated. IRIP overexpression inhibited endogenous 1-methyl-4-phenylpyridinium (MPP+) uptake activity in HeLa cells. The activities of exogenous organic cation transporters (OCT2 and OCT3), organic anion transporter (OAT1), and monoamine transporters were also inhibited by IRIP. Conversely, inhibition of IRIP expression by small interfering RNA or antisense RNA increased MPP+ uptake. We measured transport kinetics of OCT2-mediated uptake and demonstrated that IRIP overexpression significantly decreased Vmax but did not affect Km. On the basis of these results, we propose that IRIP regulates the activity of a variety of transporters under normal and pathological conditions. PMID:16024787

  19. Development and testing of heat transport fluids for use in active solar heating and cooling systems

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1981-01-01

    Work on heat transport fluids for use with active solar heating and cooling systems is described. Program objectives and how they were accomplished including problems encountered during testing are discussed.

  20. Dopamine Transporter Genotype Conveys Familial Risk of Attention-Deficit/Hyperactivity Disorder through Striatal Activation

    ERIC Educational Resources Information Center

    Durston, Sarah; Fossella, John A.; Mulder, Martijn J.; Casey B. J.; Ziermans, Tim B.; Vessaz, M. Nathalie; Van Engeland, Herman

    2008-01-01

    The study examines the effect of the dopamine transporter (DAT1) genotype in attention-deficit/hyperactivity disorder (ADHD). The results confirm that DAT1 translates the genetic risk of ADHD through striatal activation.

  1. The PP-motif in luminal loop 2 of ZnT transporters plays a pivotal role in TNAP activation.

    PubMed

    Fujimoto, Shigeyuki; Tsuji, Tokuji; Fujiwara, Takashi; Takeda, Taka-Aki; Merriman, Chengfeng; Fukunaka, Ayako; Nishito, Yukina; Fu, Dax; Hoch, Eitan; Sekler, Israel; Fukue, Kazuhisa; Miyamae, Yusaku; Masuda, Seiji; Nagao, Masaya; Kambe, Taiho

    2016-09-01

    Secretory and membrane-bound zinc-requiring enzymes are thought to be activated by binding zinc in the early secretory pathway. One such enzyme, tissue-non-specific alkaline phosphatase (TNAP), is activated through a two-step mechanism, via protein stabilization and subsequent enzyme activation through metalation, by ZnT5-ZnT6 heterodimers or ZnT7 homodimers. However, little is known about the molecular basis underlying the activation process. In the present study, we found that the di-proline motif (PP-motif) in luminal loop 2 of ZnT5 and ZnT7 is important for TNAP activation. TNAP activity was significantly reduced in cells lacking ZnT5-ZnT6 heterodimers and ZnT7 homodimers [triple knockout (TKO) cells]. The decreased TNAP activity was restored by expressing hZnT5 with hZnT6 or hZnT7, but significantly less so (almost 90% less) by expressing mutants thereof in which the PP-motif was mutated to alanine (PP-AA). In TKO cells, overexpressed hTNAP was not completely activated, and it was converted less efficiently into the holo form by expressing a PP-AA mutant of hZnT5 with hZnT6, whose defects were not restored by zinc supplementation. The zinc transport activity of hZnT7 was not significantly impaired by the PP-AA mutation, indicating that the PP-motif is involved in the TNAP maturation process, although it does not control zinc transport activity. The PP-motif is highly conserved in ZnT5 and ZnT7 orthologues, and its importance for TNAP activation is conserved in the Caenorhabditis elegans hZnT5 orthologue CDF5. These results provide novel molecular insights into the TNAP activation process in the early secretory pathway. PMID:27303047

  2. Low-temperature photo-activated inorganic electron transport layers for flexible inverted polymer solar cells

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Wook; Lee, Soo-Hyoung; Kim, Yong-Hoon; Park, Sung Kyu

    2014-09-01

    A simple and versatile route of forming sol-gel-derived metal oxide n-type electron transport layers (ETLs) for flexible inverted polymer solar cells (PSCs) is proposed using low-temperature photochemical activation process. The photochemical activation, which is induced by deep ultraviolet irradiation on sol-gel films, allows formation of metal oxide n-type ETLs such as zinc oxide (ZnO) and indium gallium zinc oxide films at a low temperature. Compared to poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester inverted PSCs with thermally annealed ZnO ETLs (optimized efficiency of 3.26 ± 0.03 %), the inverted PSCs with photo-activated ZnO ETLs showed an improved efficiency of 3.60 ± 0.02 %. The enhanced photovoltaic property is attributed to efficient charge collection from low overall series resistance and high surface area-to-geometric area ratio by the photo-activated ZnO ETLs.

  3. Parental Involvement in Active Transport to School Initiatives: A Multi-Site Case Study

    ERIC Educational Resources Information Center

    Eyler, Amy; Baldwin, Julie; Carnoske, Cheryl; Nickelson, Jan; Troped, Philip; Steinman, Lesley; Pluto, Delores; Litt, Jill; Evenson, Kelly; Terpstra, Jennifer; Brownson, Ross; Schmid, Thomas

    2008-01-01

    Background: Increasing physical activity in youth is a recommended approach to curbing the childhood obesity epidemic. One way to help increase children's daily activity is to promote active transportation to and from school (ATS). Purpose: The purpose of this case study was to explore parental perception of, and participation in, ATS initiatives.…

  4. Disposition and transportation of surplus radioactive low specific activity nitric acid. Volume 1, Environmental Assessment

    SciTech Connect

    1995-05-01

    DOE is deactivating the PUREX plant at Hanford; this will involve the disposition of about 692,000 liters (183,000 gallons) of surplus nitric acid contaminated with low levels of U and other radionuclides. The nitric acid, designated as low specific activity, is stored in 4 storage tanks at PUREX. Five principal alternatives were evaluated: transfer for reuse (sale to BNF plc), no action, continued storage in Hanford upgraded or new facility, consolidation of DOE surplus acid, and processing the LSA nitric acid as waste. The transfer to BNF plc is the preferred alternative. From the analysis, it is concluded that the proposed disposition and transportation of the acid does not constitute a major federal action significantly affecting the quality of the human environment within the meaning of NEPA; therefore an environmental impact statement is not required.

  5. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-10-07

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  6. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, G.G.; Kato, T.R.; Schonegg, E.

    1985-04-11

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed. 5 tabs.

  7. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-01-01

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  8. Neuronal activity mediated regulation of glutamate transporter GLT-1 surface diffusion in rat astrocytes in dissociated and slice cultures.

    PubMed

    Al Awabdh, Sana; Gupta-Agarwal, Swati; Sheehan, David F; Muir, James; Norkett, Rosalind; Twelvetrees, Alison E; Griffin, Lewis D; Kittler, Josef T

    2016-07-01

    The astrocytic GLT-1 (or EAAT2) is the major glutamate transporter for clearing synaptic glutamate. While the diffusion dynamics of neurotransmitter receptors at the neuronal surface are well understood, far less is known regarding the surface trafficking of transporters in subcellular domains of the astrocyte membrane. Here, we have used live-cell imaging to study the mechanisms regulating GLT-1 surface diffusion in astrocytes in dissociated and brain slice cultures. Using GFP-time lapse imaging, we show that GLT-1 forms stable clusters that are dispersed rapidly and reversibly upon glutamate treatment in a transporter activity-dependent manner. Fluorescence recovery after photobleaching and single particle tracking using quantum dots revealed that clustered GLT-1 is more stable than diffuse GLT-1 and that glutamate increases GLT-1 surface diffusion in the astrocyte membrane. Interestingly, the two main GLT-1 isoforms expressed in the brain, GLT-1a and GLT-1b, are both found to be stabilized opposed to synapses under basal conditions, with GLT-1b more so. GLT-1 surface mobility is increased in proximity to activated synapses and alterations of neuronal activity can bidirectionally modulate the dynamics of both GLT-1 isoforms. Altogether, these data reveal that astrocytic GLT-1 surface mobility, via its transport activity, is modulated during neuronal firing, which may be a key process for shaping glutamate clearance and glutamatergic synaptic transmission. GLIA 2016;64:1252-1264. PMID:27189737

  9. Entropy production and Onsager symmetry in neoclassical transport processes of toroidal plasmas

    SciTech Connect

    Sugama, H.; Horton, W.

    1996-01-01

    Entropy production and Onsager symmetry in neoclassical transport processes of magnetically confined plasmas are studied in detail for general toroidal systems, including nonaxisymmetric configurations. It is found that the flux surface average of the entropy production defined from the linearized collision operator and the gyroangle-averaged distribution function coincides with the sum of the inner products of the thermodynamic forces and the conjugate fluxes consisting of the Pfirsch-Schlueter, banana-plateau, nonaxisymmetric parts of the neoclassical radial fluxes and the parallel current. It is proved from the self-adjointness of the linearized collision operator that the Onsager symmetry is robustly valid for the neoclassical transport equations in the cases of general toroidal plasmas consisting of electrons and multi-species ions with arbitrary collision frequencies. It is shown that the Onsager symmetry holds whether or not the ambipolarity condition is used to reduce the number of the conjugate pairs of the transport fluxes and the thermodynamic forces. The full transport coefficients for the banana-plateau and nonaxisymmetric parts are separately derived, and their symmetry properties are investigated. The nonaxisymmetric transport equations are obtained for arbitrary collision frequencies in the Pfirsch{endash}Schlueter and plateau regimes, and it is directly confirmed that the total banana-plateau and nonaxisymmetric transport equations satisfy the Onsager symmetry. {copyright} {ital 1996 American Institute of Physics.}

  10. RESEARCH ACTIVITIES AT U.S. GOVERNMENT AGENCIES IN SUBSURFACE REACTIVE TRANSPORT MODELING

    EPA Science Inventory

    The fate of contaminants in the environment is controlled by both chemical reactions and transport phenomena in the subsurface. Our ability to understand the significance of these processes over time requires an accurate conceptual model that incorporates the various mechanisms ...

  11. Statistics of Active Transport in Xenopus Melanophores Cells

    PubMed Central

    Snezhko, Alexey; Barlan, Kari; Aranson, Igor S.; Gelfand, Vladimir I.

    2010-01-01

    The transport of cell cargo, such as organelles and protein complexes in the cytoplasm, is determined by cooperative action of molecular motors stepping along polar cytoskeletal elements. Analysis of transport of individual organelles generated useful information about the properties of the motor proteins and underlying cytoskeletal elements. In this work, for the first time (to our knowledge), we study collective movement of multiple organelles using Xenopus melanophores, pigment cells that translocate several thousand of pigment granules (melanosomes), spherical organelles of a diameter of ∼1 μm. These cells disperse melanosomes in the cytoplasm in response to high cytoplasmic cAMP, while at low cAMP melanosomes cluster at the cell center. Obtained results suggest spatial and temporal organization, characterized by strong correlations between movement of neighboring organelles, with correlation length of ∼4 μm and pair lifetime ∼5 s. Furthermore, velocity statistics revealed strongly non-Gaussian velocity distribution with high velocity tails demonstrating exponential behavior suggestive of strong velocity correlations. Depolymerization of vimentin intermediate filaments using a dominant-negative vimentin mutant or actin with cytochalasin B reduced correlation of behavior of individual particles. Based on our analysis, we concluded that steric repulsion is dominant, but both intermediate filaments and actin microfilaments are involved in dynamic cross-linking organelles in the cytoplasm. PMID:21081069

  12. Statistics of active transport in Xenopus melanophores cells.

    SciTech Connect

    Snezhko, A.; Barlan, K.; Aranson, I. S.; Gelfand, V. I.; Materials Science Division; Northwestern Univ.

    2010-11-01

    The transport of cell cargo, such as organelles and protein complexes in the cytoplasm, is determined by cooperative action of molecular motors stepping along polar cytoskeletal elements. Analysis of transport of individual organelles generated useful information about the properties of the motor proteins and underlying cytoskeletal elements. In this work, for the first time (to our knowledge), we study collective movement of multiple organelles using Xenopus melanophores, pigment cells that translocate several thousand of pigment granules (melanosomes), spherical organelles of a diameter of {approx} 1 {micro}m. These cells disperse melanosomes in the cytoplasm in response to high cytoplasmic cAMP, while at low cAMP melanosomes cluster at the cell center. Obtained results suggest spatial and temporal organization, characterized by strong correlations between movement of neighboring organelles, with correlation length of {approx} 4 {micro}m and pair lifetime {approx} 5 s. Furthermore, velocity statistics revealed strongly non-Gaussian velocity distribution with high velocity tails demonstrating exponential behavior suggestive of strong velocity correlations. Depolymerization of vimentin intermediate filaments using a dominant-negative vimentin mutant or actin with cytochalasin B reduced correlation of behavior of individual particles. Based on our analysis, we concluded that steric repulsion is dominant, but both intermediate filaments and actin microfilaments are involved in dynamic cross-linking organelles in the cytoplasm.

  13. Hydraulics and sediment transport processes in a pool-riffle rocky mountain stream

    USGS Publications Warehouse

    Thompson, Douglas M.

    1994-01-01

    Sediment transport processes related to varying channel-bed morphology were investigated from April to November, 1993 along a 1 km pool-riffle and step-pool reach of North Saint Vrain Creek, a small mountain stream in the Northern Colorado Rocky Mountains. Three hundred sixteen 16-256 mm tracer particles placed in two separate pool-riffle-pool sequences, forty-three direct bedload measurements at three separate cross-sections in discharges ranging between 0.27-8.8 m3/s, and indirect velocity measurements at thirteen cross-sections in 23 discharges ranging between 0.23-9.2 m3/s are used to assess sediment sorting patterns and sediment transport capacity variations. An investigation of secondary flow features and wave patterns provides preliminary evidence of turbulent controls on sediment entrainment and transport, and was used to develop a conceptual model of bedload transport and channel-bed maintenance on North Saint Vrain Creek. Recirculating eddy systems provide a means to constrict flow in pools, leading to modeled velocity-reversals at high flows. Tracer particle depositional evidence also indicates higher sediment transport capacities in pools versus riffles at high flow. Modeled hydraulic conditions and depositional evidence of tracers indicates that high-flow recirculating-eddy-influenced velocity-reversals and associated turbulence may provide the primary pool maintenance processes in this channel.

  14. Saharan Dust Export towards the Caribbean: Transport, Mixing and Deposition Processes over the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Heinold, Bernd; Schepanski, Kerstin; Haarig, Moritz; Ansmann, Albert; Groß, Silke; Schäfler, Andreas; Weinzierl, Bernadett; Tegen, Ina

    2015-04-01

    Large amounts of Saharan dust are carried towards the Caribbean within the Saharan Air Layer (SAL), with maximum transport in late boreal spring and early summer. During long-range transport, the dust particles are transformed by aging and mixing, which may have significant but as yet unquantified effects on the dust impact on radiation, cloud properties, and the biogeochemical processes of ecosystems. Here, we investigate the long-range transport of Saharan dust across the Atlantic Ocean by means of transport modelling that has been performed within the framework of the SALTRACE (Saharan Aerosol Long-Range Transport and Aerosol-Cloud Interaction Experiment) project. The emission, transport, dry and wet deposition of Saharan dust as well as the effect of dust radiative forcing are simulated with the regional model COSMO-MUSCAT. The model results are evaluated against the various ground and airborne observations from the SALTRACE field measurements at Barbados Island in June and July 2013. The dust simulations, in turn, help to interpret the observations, in particular from a Lagrangian flight experiment, by providing a spatiotemporal context. Specifically, this study addresses the questions of (a) how the Saharan dust export towards the Caribbean is influenced by the atmospheric circulation over West Africa, (b) which role the different removal and mixing processes play during long-range transport, and (c) what is the impact of dust forcing on the vertical structure of the SAL? In addition, the Saharan dust simulations with COSMO-MUSCAT are combined with trajectory analysis to study particle aging and dust-cloud interactions.

  15. Modeling water stability and transport on Mars and Iapetus: Exploring their effects on geomorphic and atmospheric processes

    NASA Astrophysics Data System (ADS)

    Rivera-Valentin, Edgard G.

    2012-05-01

    The stability and transport of water on solid planetary surfaces strongly affects both atmospheric and surfaces processes. In this work, two bodies are specifically investigated where transport of water is relevant: Iapetus and Mars. Iapetus, an icy Kronian satellite, has a drastic albedo contrast on its surface and one of the darkest surfaces in the solar system. This extreme brightness contrast is suggested to occur via the transport of water ice from the leading hemisphere to the trailing hemisphere and the poles. Here a global heat and mass transfer model is developed for Iapetus in order to study the current state of H2O transport and to make inferences about the temporal evolution of this process on its surface. On Mars, atmosphere-regolith interactions have been suggested to control the near-surface water vapor cycle. Due to the large amount of experimental values of the absorptivity of soil materials, a model is developed in order to study the effects of an active regolith on the transport of water vapor. Liquid water has been a controversial subject in the martian literature. However, there exists sufficient evidence of past standing bodies of liquid on Mars. If these paleolakes contained dissolved salts, their evolution would be drastically affected. Therefore, a model is developed in order to study the effect of dissolved salts and investigate if there exists the possibility for brine residue formation. Recent observations also strongly suggest that liquid may be possible on present-day Mars. A model is developed in order to investigate the possibility of brine flows as the source for recurring slope lineae.

  16. Kinetics of Ion Transport in Perovskite Active Layers and Its Implications for Active Layer Stability.

    PubMed

    Bag, Monojit; Renna, Lawrence A; Adhikari, Ramesh Y; Karak, Supravat; Liu, Feng; Lahti, Paul M; Russell, Thomas P; Tuominen, Mark T; Venkataraman, D

    2015-10-14

    Solar cells fabricated using alkyl ammonium metal halides as light absorbers have the right combination of high power conversion efficiency and ease of fabrication to realize inexpensive but efficient thin film solar cells. However, they degrade under prolonged exposure to sunlight. Herein, we show that this degradation is quasi-reversible, and that it can be greatly lessened by simple modifications of the solar cell operating conditions. We studied perovskite devices using electrochemical impedance spectroscopy (EIS) with methylammonium (MA)-, formamidinium (FA)-, and MA(x)FA(1-x) lead triiodide as active layers. From variable temperature EIS studies, we found that the diffusion coefficient using MA ions was greater than when using FA ions. Structural studies using powder X-ray diffraction (PXRD) show that for MAPbI3 a structural change and lattice expansion occurs at device operating temperatures. On the basis of EIS and PXRD studies, we postulate that in MAPbI3 the predominant mechanism of accelerated device degradation under sunlight involves thermally activated fast ion transport coupled with a lattice-expanding phase transition, both of which are facilitated by absorption of the infrared component of the solar spectrum. Using these findings, we show that the devices show greatly improved operation lifetimes and stability under white-light emitting diodes, or under a solar simulator with an infrared cutoff filter or with cooling. PMID:26414066

  17. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... (12 CFR part 225) at that time, as the Regulation K authority permitted limited non-financial data... data processing or data transmission activities beyond those described in Regulation Y, it must...

  18. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 2 2013-01-01 2013-01-01 false Data processing activities. 211.604 Section 211.604 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM INTERNATIONAL BANKING OPERATIONS (REGULATION K) International Lending Supervision Interpretations § 211.604 Data processing activities. (a)...

  19. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... (12 CFR part 225) at that time, as the Regulation K authority permitted limited non-financial data... 12 Banks and Banking 2 2014-01-01 2014-01-01 false Data processing activities. 211.604 Section...

  20. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... (12 CFR part 225) at that time, as the Regulation K authority permitted limited non-financial data... 12 Banks and Banking 2 2012-01-01 2012-01-01 false Data processing activities. 211.604 Section...

  1. 12 CFR 211.604 - Data processing activities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... processing activities under Regulation K (12 CFR part 211). This question has arisen as a result of the fact... (12 CFR part 225) at that time, as the Regulation K authority permitted limited non-financial data... 12 Banks and Banking 2 2011-01-01 2011-01-01 false Data processing activities. 211.604 Section...

  2. Modeling watershed-scale solute transport using an integrated, process-based hydrologic model with applications to bacterial fate and transport

    NASA Astrophysics Data System (ADS)

    Niu, Jie; Phanikumar, Mantha S.

    2015-10-01

    Distributed hydrologic models that simulate fate and transport processes at sub-daily timescales are useful tools for estimating pollutant loads exported from watersheds to lakes and oceans downstream. There has been considerable interest in the application of integrated process-based hydrologic models in recent years. While the models have been applied to address questions of water quantity and to better understand linkages between hydrology and land surface processes, routine applications of these models to address water quality issues are currently limited. In this paper, we first describe a general process-based watershed-scale solute transport modeling framework, based on an operator splitting strategy and a Lagrangian particle transport method combined with dispersion and reactions. The transport and the hydrologic modules are tightly coupled and the interactions among different hydrologic components are explicitly modeled. We test transport modules using data from plot-scale experiments and available analytical solutions for different hydrologic domains. The numerical solutions are also compared with an analytical solution for groundwater transit times with interactions between surface and subsurface flows. Finally, we demonstrate the application of the model to simulate bacterial fate and transport in the Red Cedar River watershed in Michigan and test hypotheses about sources and transport pathways. The watershed bacterial fate and transport model is expected to be useful for making near real-time predictions at marine and freshwater beaches.

  3. In vitro reconstitution of an mRNA-transport complex reveals mechanisms of assembly and motor activation

    PubMed Central

    Heym, Roland G.; Zimmermann, Dennis; Edelmann, Franziska T.; Israel, Lars; Ökten, Zeynep; Kovar, David R.

    2013-01-01

    The assembly and composition of ribonucleic acid (RNA)–transporting particles for asymmetric messenger RNA (mRNA) localization is not well understood. During mitosis of budding yeast, the Swi5p-dependent HO expression (SHE) complex transports a set of mRNAs into the daughter cell. We recombinantly reconstituted the core SHE complex and assessed its properties. The cytoplasmic precomplex contains only one motor and is unable to support continuous transport. However, a defined interaction with a second, RNA-bound precomplex after its nuclear export dimerizes the motor and activates processive RNA transport. The run length observed in vitro is compatible with long-distance transport in vivo. Surprisingly, SHE complexes that either contain or lack RNA cargo show similar motility properties, demonstrating that the RNA-binding protein and not its cargo activates motility. We further show that SHE complexes have a defined size but multimerize into variable particles upon binding of RNAs with multiple localization elements. Based on these findings, we provide an estimate of number, size, and composition of such multimeric SHE particles in the cell. PMID:24368805

  4. Calculation tool for transported geothermal energy using two-step absorption process

    DOE Data Explorer

    Kyle Gluesenkamp

    2016-02-01

    This spreadsheet allows the user to calculate parameters relevant to techno-economic performance of a two-step absorption process to transport low temperature geothermal heat some distance (1-20 miles) for use in building air conditioning. The parameters included are (1) energy density of aqueous LiBr and LiCl solutions, (2) transportation cost of trucking solution, and (3) equipment cost for the required chillers and cooling towers in the two-step absorption approach. More information is available in the included public report: "A Technical and Economic Analysis of an Innovative Two-Step Absorption System for Utilizing Low-Temperature Geothermal Resources to Condition Commercial Buildings"

  5. Synchronization of elastically coupled processive molecular motors and regulation of cargo transport

    NASA Astrophysics Data System (ADS)

    Kohler, Felix; Rohrbach, Alexander

    2015-01-01

    The collective work of motor proteins plays an important role in cellular transport processes. Since measuring intermotor coupling and hence a comparison to theoretical predictions is difficult, we introduce the synchronization as an alternative observable for motor cooperativity. This synchronization can be determined from the ratio of the mean times of motor resting and stepping. Results from a multistate Markov chain model and Brownian dynamics simulations, describing the elastically coupled motors, coincide well. Our model can explain the experimentally observed effect of strongly increased transport velocities and powers by the synchronization and coupling of myosin V and kinesin I.

  6. Active membrane transport and receptor proteins from bacteria.

    PubMed

    Saidijam, M; Bettaney, K E; Szakonyi, G; Psakis, G; Shibayama, K; Suzuki, S; Clough, J L; Blessie, V; Abu-Bakr, A; Baumberg, S; Meuller, J; Hoyle, C K; Palmer, S L; Butaye, P; Walravens, K; Patching, S G; O'reilly, J; Rutherford, N G; Bill, R M; Roper, D I; Phillips-Jones, M K; Henderson, P J F

    2005-08-01

    A general strategy for the expression of bacterial membrane transport and receptor genes in Escherichia coli is described. Expression is amplified so that the encoded proteins comprise 5-35% of E. coli inner membrane protein. Depending upon their topology, proteins are produced with RGSH6 or a Strep tag at the C-terminus. These enable purification in mg quantities for crystallization and NMR studies. Examples of one nutrient uptake and one multidrug extrusion protein from Helicobacter pylori are described. This strategy is successful for membrane proteins from H. pylori, E. coli, Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, Microbacterium liquefaciens, Brucella abortus, Brucella melitensis, Campylobacter jejuni, Neisseria meningitides, Streptomyces coelicolor and Rhodobacter sphaeroides. PMID:16042616

  7. Barrier Crossing and Transport Activated by Kangaroo Fluctuations

    NASA Astrophysics Data System (ADS)

    Kostur, M.; Luczka, J.

    1999-01-01

    We study barrier crossing of Brownian particles in a bistable symmetric potential and transport of Brownian particles in spatially periodic structures, driven by both kangaroo fluctuations and thermal equilibrium noise of zero mean values. We consider exponentially and algebraically correlated kangaroo fluctuations. Starting with the full Newton--Langevin equation for the Brownian particle and by introducing scaling as well as dimensionless variables, we show that the equation is very well approximated by overdamped dynamics in which inertial effects can be neglected. We analyze properties of selected macroscopic characteristics of the system such as the mean first passage time (MFPT) of particles from one minimum of the bistable potential to the other and mean stationary velocity of particles moving in a spatially periodic potential. In dependence upon statistics of kangaroo fluctuations and temperature of the system, macroscopic characteristics exhibit distinctive non-monotonic behavior. Accordingly, there exist optimal statistics of fluctuations optimizing macroscopic characteristics.

  8. Assessment of controlling processes for field-scale uranium reactive transport under highly transient flow conditions

    NASA Astrophysics Data System (ADS)

    Ma, Rui; Zheng, Chunmiao; Liu, Chongxuan; Greskowiak, Janek; Prommer, Henning; Zachara, John M.

    2014-02-01

    This paper presents the results of a comprehensive model-based analysis of a uranyl [U(VI)] tracer test conducted at the U.S. DOE Hanford 300 Area (300A) IFRC. Despite the highly complex field conditions the numerical three-dimensional multicomponent reactive transport model was able to capture most of the spatiotemporal variations of the observed U(VI) concentrations. A multimodel analysis was performed to interrogate the relative importance of various processes and factors for controlling field-scale reactive transport during the uranyl tracer test. The results indicate that multirate sorption/desorption, surface complexation reactions, and initial concentration distributions were the most important processes and factors controlling U(VI) migration. On the other hand, cation exchange reactions, the choice of the surface complexation model, and dual-domain mass transfer processes played less important roles under the prevailing field-test conditions. Further analysis of the modeling results demonstrates that these findings are conditioned to the relatively stable groundwater chemistry and the selected length of the field experimental duration (16 days). The model analysis also revealed the crucial role of the intraborehole flow that occurred within the long-screened monitoring wells and thus affected both field measurements and simulated U(VI) concentrations as a combined effect of aquifer heterogeneity and dynamic flow conditions. This study provides the first highly data-constrained uranium transport simulations under highly dynamic flow conditions. It illustrates the value of reactive transport modeling for elucidating the relative importance of individual processes in controlling uranium transport under specific field-scale conditions.

  9. A biophysical analysis of mitochondrial movement: differences between transport in neuronal cell bodies versus processes.

    PubMed

    Narayanareddy, Babu Reddy Janakaloti; Vartiainen, Suvi; Hariri, Neema; O'Dowd, Diane K; Gross, Steven P

    2014-07-01

    There is an increasing interest in factors that can impede cargo transport by molecular motors inside the cell. Although potentially relevant (Yi JY, Ori-McKenney KM, McKenney RJ, Vershinin M, Gross SP, Vallee RB. High-resolution imaging reveals indirect coordination of opposite motors and a role for LIS1 in high-load axonal transport. J Cell Biol 2011;195:193-201), the importance of cargo size and subcellular location has received relatively little attention. Here we address these questions taking advantage of the fact that mitochondria - a common cargo - in Drosophila neurons exhibit a wide distribution of sizes. In addition, the mitochondria can be genetically marked with green fluorescent protein (GFP) making it possible to visualize and compare their movement in the cell bodies and in the processes of living cells. Using total internal reflection microscopy coupled with particle tracking and analysis, we quantified the transport properties of GFP-positive mitochondria as a function of their size and location. In neuronal cell bodies, we find little evidence for significant opposition to motion, consistent with a previous study on lipid droplets (Shubeita GT, Tran SL, Xu J, Vershinin M, Cermelli S, Cotton SL, Welte MA, Gross SP. Consequences of motor copy number on the intracellular transport of kinesin-1-driven lipid droplets. Cell 2008;135:1098-1107). However, in the processes, we observe an inverse relationship between the mitochondrial size and velocity and the run distances. This can be ameliorated via hypotonic treatment to increase process size, suggesting that motor-mediated movement is impeded in this more-confined environment. Interestingly, we also observe local mitochondrial accumulations in processes but not in cell bodies. Such accumulations do not completely block the transport but do increase the probability of mitochondria-mitochondria interactions. They are thus particularly interesting in relation to mitochondrial exchange of elements

  10. Enhancement of carrier-mediated transport after immunologic activation of peritoneal macrophages.

    PubMed

    Bonventre, P F; Straus, D; Baughn, R E; Imhoff, J

    1977-05-01

    Immunologically activated peritoneal macrophages from inbred mice and Hartley strain guinea pigs demonstrate a markedly greater than normal transport of 2-deoxy-D-glucose and L-leucine. The degree of nutrilite transport enhancement was greatest when animals were injected with the appropriate eliciting antigens before harvesting and also, if antigen was included in the tissue culture medium during the initial hours of in vitro culture. Enhanced hexose and amino acid uptake could also be achieved by exposure of macrophages from nonimmunized animals for 48 hr to supernatants of sensitized splenic lymphocyte cultures incubated with specific antigens. The animal systems in which this phenomenon was observed included CBA/J and C57BL/6J mice immunized with Staphylococcus aureus or sub-lethal doses of Listeria monocytogens, and the Hartley strain, albino guinea pig immunized with S. aureus or BCG. In all cases, immunization resulted in a state of delayed hypersensitivity as measured by skin testing or footpad swelling. Splenic cell supernatants contained lymphokines as detected by the presence of macrophage inhibitory factor (MIF), and by the supernatants' capacity to stimulate incorporation of 14C-glucosamine by macrophages in vitro. No increase of glucose or leucine transport by macrophages was observed in the absence of appropriate antigen stimulation in vivo or in vitro. We previously showed that a phagocytic stimulus results in a significant increase in hexose transport by normal macrophages; leucine transport by these same cells was unaltered after phagocytosis. In contrast, immunologically activated macrophages do not transport measurably more 2-deoxy-C-glucose after particle ingestion; activation or the phagocytic stimulus enhance 2-deoxy-C-glucose uptake to approximately the same extent. Analysis of nutrilite transport kinetics revealed that immunologic activation of macrophages increases the initial velocity (V1) and Vmax but does not change the Km values of

  11. Moditored unsaturated soil transport processes as a support for large scale soil and water management

    NASA Astrophysics Data System (ADS)

    Vanclooster, Marnik

    2010-05-01

    The current societal demand for sustainable soil and water management is very large. The drivers of global and climate change exert many pressures on the soil and water ecosystems, endangering appropriate ecosystem functioning. The unsaturated soil transport processes play a key role in soil-water system functioning as it controls the fluxes of water and nutrients from the soil to plants (the pedo-biosphere link), the infiltration flux of precipitated water to groundwater and the evaporative flux, and hence the feed back from the soil to the climate system. Yet, unsaturated soil transport processes are difficult to quantify since they are affected by huge variability of the governing properties at different space-time scales and the intrinsic non-linearity of the transport processes. The incompatibility of the scales between the scale at which processes reasonably can be characterized, the scale at which the theoretical process correctly can be described and the scale at which the soil and water system need to be managed, calls for further development of scaling procedures in unsaturated zone science. It also calls for a better integration of theoretical and modelling approaches to elucidate transport processes at the appropriate scales, compatible with the sustainable soil and water management objective. Moditoring science, i.e the interdisciplinary research domain where modelling and monitoring science are linked, is currently evolving significantly in the unsaturated zone hydrology area. In this presentation, a review of current moditoring strategies/techniques will be given and illustrated for solving large scale soil and water management problems. This will also allow identifying research needs in the interdisciplinary domain of modelling and monitoring and to improve the integration of unsaturated zone science in solving soil and water management issues. A focus will be given on examples of large scale soil and water management problems in Europe.

  12. Light and Sound: Evolutionary Aspects. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Roseman, Leonard D.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module is concerned with the exchange of energy between an organism and its environment in…

  13. Pressure and Buoyancy in Aquatic Ecosystems. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Cowan, Christina E.

    This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module explores some of the characteristics of aquatic organisms which can be…

  14. Fluid Dynamics Applied to Streams. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Cowan, Christina E.

    This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module deals specifically with concepts that are basic to fluid flow and…

  15. Transpiration and Leaf Temperature. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Gates, David M.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This report introduces two models of the thermal energy budget of a leaf. Typical values for…

  16. Soil Heat Flow. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Simpson, James R.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. Soil heat flow and the resulting soil temperature distributions have ecological consequences…

  17. Activated Sludge and other Aerobic Suspended Culture Processes.

    PubMed

    Li, Chunying; Wei, Li; Chang, Chein-Chi; Zhang, Yuhua; Wei, Dong

    2016-10-01

    This is a literature review for the year 2015 and contains information specifically associated with suspended growth processes including activated sludge, upflow anaerobic sludge blanket, and sequencing batch reactors. The review encompasses modeling and kinetics, nutrient removal, system design and operation. Compared to past reviews, many topics show increase in activity in 2015. These include, fate and effect of xenobiotics, industrial wastes treatment with sludge, and pretreatment for the activated sludge. These topics are referred to the degradation of constituents in activated sludge. Other sections include population dynamics, process microbiology give an insight into the activated sludge. The subsection in industrial wastes: converting sewage sludge into biogases was also mentioned. PMID:27620082

  18. Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

    SciTech Connect

    Sode, Olaseni; Voth, Gregory A.

    2014-12-14

    Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A{sup 2−}, a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A{sup 2-} by closing a cavity that could otherwise fill with water near the proximal Fe of the active site.

  19. Role of thyroxine on postnatal development of ileal active bile salt transport

    SciTech Connect

    Heubi, J.E.

    1986-08-01

    The role of thyroid hormone on the postnatal development of ileal active taurocholate transport uptake was measured by an in vitro incubation technique in Sprague-Dawley rats. In 16-day-old rats treated with pharmacological doses of L-thyroxine ileal active transport appeared precociously whose K/sub m/ was 1.60 +/- 0.48 mM and V/sub app/ was 8.09 +/- 1.14 nmol min mg dry wt , while age-matched shams had only passive diffusion of taurocholate. To determine whether enhanced endogenous secretion of thyroxine was capable of stimulating development of ileal active taurocholate transport, thyrotrophic stimulating hormone (TSH) was given on days 10-13, with uptake measured on day 16. Following TSH treatment, only passive transport for taurocholate was observed in the ileum; uptake rates were consistently higher than those for untreated controls at each study concentration. Thyroidectomy performed at age 14 days with uptake measured at age 21 days did not ablate development of ileal active transport but resulted in a significant reduction in the V/sub app/ and a significant increase in K/sub m/ compared with age-matched controls. Thyroid hormone does not appear to be obligatory for the postnatal development of ileal active taurocholate transport.

  20. Investigation of Micro- and Macro-Scale Transport Processes for Improved Fuel Cell Performance

    SciTech Connect

    Gu, Wenbin

    2015-02-05

    This report documents the work performed by General Motors (GM) under the Cooperative agreement No. DE-EE0000470, “Investigation of Micro- and Macro-Scale Transport Processes for Improved Fuel Cell Performance,” in collaboration with the Penn State University (PSU), University of Tennessee Knoxville (UTK), Rochester Institute of Technology (RIT), and University of Rochester (UR) via subcontracts. The overall objectives of the project are to investigate and synthesize fundamental understanding of transport phenomena at both the macro- and micro-scales for the development of a down-the-channel model that accounts for all transport domains in a broad operating space. GM as a prime contractor focused on cell level experiments and modeling, and the Universities as subcontractors worked toward fundamental understanding of each component and associated interface.

  1. Active transportation to school in Canadian youth: should injury be a concern?

    PubMed

    Gropp, Kathleen; Janssen, Ian; Pickett, William

    2013-02-01

    Active transportation to school provides a means for youth to incorporate physical activity into their daily routines, and this has obvious benefits for child health. Studies of active transportation have rarely focused on the negative health effects in terms of injury. This cross-sectional study is based on the 2009/10 Canadian Health Behaviour in School-Aged Children survey. A sample of children aged 11-15 years (n=20 076) was studied. Multi-level logistic regression was used to examine associations between walking or bicycling to school and related injury. Regular active transportation to school at larger distances (approximately >1.6 km; 1.0 miles) was associated with higher relative odds of active transportation injury (OR: 1.52; 95% CI 1.08 to 2.15), with a suggestion of a dose-response relationship between longer travel distances and injury (p=0.02). Physical activity interventions for youth should encourage participation in active transportation to school, while also recognising the potential for unintentional injury. PMID:22627782

  2. Neuronal transporter and astrocytic ATP exocytosis underlie activity-dependent adenosine release in the hippocampus

    PubMed Central

    Wall, Mark J; Dale, Nicholas

    2013-01-01

    The neuromodulator adenosine plays an important role in many physiological and pathological processes within the mammalian CNS. However, the precise mechanisms of how the concentration of extracellular adenosine increases following neural activity remain contentious. Here we have used microelectrode biosensors to directly measure adenosine release induced by focal stimulation in stratum radiatum of area CA1 in mouse hippocampal slices. Adenosine release was both action potential and Ca2+ dependent and could be evoked with low stimulation frequencies and small numbers of stimuli. Adenosine release required the activation of ionotropic glutamate receptors and could be evoked by local application of glutamate receptor agonists. Approximately 40% of stimulated-adenosine release occurred by translocation of adenosine via equilibrative nucleoside transporters (ENTs). This component of release persisted in the presence of the gliotoxin fluoroacetate and thus results from the direct release of adenosine from neurons. A reduction of adenosine release in the presence of NTPDase blockers, in slices from CD73−/− and dn-SNARE mice, provides evidence that a component of adenosine release arises from the extracellular metabolism of ATP released from astrocytes. This component of release appeared to have slower kinetics than the direct ENT-mediated release of adenosine. These data suggest that activity-dependent adenosine release is surprisingly complex and, in the hippocampus, arises from at least two distinct mechanisms with different cellular sources. PMID:23713028

  3. Processes governing phytoplankton blooms in estuaries. II: The role of horizontal transport

    USGS Publications Warehouse

    Lucas, L.V.; Koseff, Jeffrey R.; Monismith, Stephen G.; Cloern, J.E.; Thompson, J.K.

    1999-01-01

    The development and distribution of phytoplankton blooms in estuaries are functions of both local conditions (i.e. the production-loss balance for a water column at a particular spatial location) and large-scale horizontal transport. In this study, the second of a 2-paper series, we use a depth-averaged hydrodynamic-biological model to identify transport-related mechanisms impacting phytoplankton biomass accumulation and distribution on a system level. We chose South San Francisco Bay as a model domain, since its combination of a deep channel surrounded by broad shoals is typical of drowned-river estuaries. Five general mechanisms involving interaction of horizontal transport with variability in local conditions are discussed. Residual (on the order of days to weeks) transport mechanisms affecting bloom development and location include residence time/export, import, and the role of deep channel regions as conduits for mass transport. Interactions occurring on tidal time scales, i.e. on the order of hours) include the phasing of lateral oscillatory tidal flow relative to temporal changes in local net phytoplankton growth rates, as well as lateral sloshing of shoal-derived biomass into deep channel regions during ebb and back into shallow regions during flood tide. Based on these results, we conclude that: (1) while local conditions control whether a bloom is possible, the combination of transport and spatial-temporal variability in local conditions determines if and where a bloom will actually occur; (2) tidal-time-scale physical-biological interactions provide important mechanisms for bloom development and evolution. As a result of both subtidal and tidal-time-scale transport processes, peak biomass may not be observed where local conditions are most favorable to phytoplankton production, and inherently unproductive areas may be regions of high biomass accumulation.

  4. Membrane Transport Processes Analyzed by a Highly Parallel Nanopore Chip System at Single Protein Resolution.

    PubMed

    Urban, Michael; Vor der Brüggen, Marc; Tampé, Robert

    2016-01-01

    Membrane protein transport on the single protein level still evades detailed analysis, if the substrate translocated is non-electrogenic. Considerable efforts have been made in this field, but techniques enabling automated high-throughput transport analysis in combination with solvent-free lipid bilayer techniques required for the analysis of membrane transporters are rare. This class of transporters however is crucial in cell homeostasis and therefore a key target in drug development and methodologies to gain new insights desperately needed. The here presented manuscript describes the establishment and handling of a novel biochip for the analysis of membrane protein mediated transport processes at single transporter resolution. The biochip is composed of microcavities enclosed by nanopores that is highly parallel in its design and can be produced in industrial grade and quantity. Protein-harboring liposomes can directly be applied to the chip surface forming self-assembled pore-spanning lipid bilayers using SSM-techniques (solid supported lipid membranes). Pore-spanning parts of the membrane are freestanding, providing the interface for substrate translocation into or out of the cavity space, which can be followed by multi-spectral fluorescent readout in real-time. The establishment of standard operating procedures (SOPs) allows the straightforward establishment of protein-harboring lipid bilayers on the chip surface of virtually every membrane protein that can be reconstituted functionally. The sole prerequisite is the establishment of a fluorescent read-out system for non-electrogenic transport substrates. High-content screening applications are accomplishable by the use of automated inverted fluorescent microscopes recording multiple chips in parallel. Large data sets can be analyzed using the freely available custom-designed analysis software. Three-color multi spectral fluorescent read-out furthermore allows for unbiased data discrimination into different

  5. Influence of karst evolution on solute transport evaluated by process-based numerical modelling

    NASA Astrophysics Data System (ADS)

    Hubinger, Bernhard; Birk, Steffen

    2010-05-01

    Karst waters are of major interest in water resources management. Because of their inherent properties karst systems show great vulnerability with regard to contaminants. Karst systems include highly permeable solution conduit networks formed by chemical aggressive water embedded in a fissured matrix. Small initial voids are widened and thus act as preferential passages, where flow is rapid and often turbulent. Water discharging at karst spring originates from different pathways with different residence times. Contaminant transport through conduit pathways is very rapid, whereas flow through the fissured porous matrix is much slower. Thus, on the one hand, pollutants may be rapidly transported and reach high concentrations at the karst spring shortly after their release; on the other hand, the existence of slow flow components may cause the pollution to last for long times. In this work, solute transport properties of karst aquifers are investigated using generic conduit networks of hydraulically connected proto-conduits with initially log-normally distributed apertures in the millimetre range and below. Conduit evolution is modelled by coupling flow, transport, and dissolution processes, whereby single conduits are widened up to the metre range. Thus, different stages of karst evolution can be distinguished. The resulting flow systems provide the basis for modelling advective-dispersive transport of non-reactive solutes through the network of more or less widened (proto-)conduits. The general transport characteristics in karst systems as well as the influence of heterogeneities and structures on solute transport are illustrated for cases of direct injection into the conduit systems at different evolutionary stages. The resulting breakthrough curves typically show several distinct, chronologically shifted peaks with long tailings, which appears to be similar to data from field tracer experiments.

  6. Neuronal activity mediated regulation of glutamate transporter GLT‐1 surface diffusion in rat astrocytes in dissociated and slice cultures

    PubMed Central

    Al Awabdh, Sana; Gupta‐Agarwal, Swati; Sheehan, David F.; Muir, James; Norkett, Rosalind; Twelvetrees, Alison E.; Griffin, Lewis D.

    2016-01-01

    The astrocytic GLT‐1 (or EAAT2) is the major glutamate transporter for clearing synaptic glutamate. While the diffusion dynamics of neurotransmitter receptors at the neuronal surface are well understood, far less is known regarding the surface trafficking of transporters in subcellular domains of the astrocyte membrane. Here, we have used live‐cell imaging to study the mechanisms regulating GLT‐1 surface diffusion in astrocytes in dissociated and brain slice cultures. Using GFP‐time lapse imaging, we show that GLT‐1 forms stable clusters that are dispersed rapidly and reversibly upon glutamate treatment in a transporter activity‐dependent manner. Fluorescence recovery after photobleaching and single particle tracking using quantum dots revealed that clustered GLT‐1 is more stable than diffuse GLT‐1 and that glutamate increases GLT‐1 surface diffusion in the astrocyte membrane. Interestingly, the two main GLT‐1 isoforms expressed in the brain, GLT‐1a and GLT‐1b, are both found to be stabilized opposed to synapses under basal conditions, with GLT‐1b more so. GLT‐1 surface mobility is increased in proximity to activated synapses and alterations of neuronal activity can bidirectionally modulate the dynamics of both GLT‐1 isoforms. Altogether, these data reveal that astrocytic GLT‐1 surface mobility, via its transport activity, is modulated during neuronal firing, which may be a key process for shaping glutamate clearance and glutamatergic synaptic transmission. GLIA 2016;64:1252–1264 PMID:27189737

  7. Changes In The Characteristics of Basaltic Particles During Different Transport Processes

    NASA Astrophysics Data System (ADS)

    Craddock, R. A.; Rose, T. R.

    2014-12-01

    The physical and chemical characteristics of the grains in sedimentary deposits can provide valuable clues about transport processes, distance traveled, and provenance. A fundamental physical characteristic is particle shape, which is diagnostic of transport process as well as the distance traveled. For example, it is possible to distinguish the emplacement process of sediments based entirely on the shape of the quartz grains in the deposit [e.g., Folk, 1980]. Such basic sedimentological concepts have been applied to our interpretation of surface materials on the terrestrial planets [e.g. Cabrol et al., 2014]. However, what we know about the nature of sedimentary materials is based primarily on sediments that have weathered from felsic rocks—granite. This is true because felsic materials compose most of the landmass on the Earth. Yet, the surface of Mars is composed predominately of mafic materials—basalt—and sedimentary particles derived from basalt are much different than those derived from granite. Instead of quartz, feldspar, and heavy minerals commonly found in most terrestrial sedimentary deposits, basaltic sediments are typically composed of varying amounts of olivine, pyroxene, plagioclase, and vitric and lithic fragments. Both the persistence of basaltic particles and their specific gravities are different than particles derived from granite. These differences are important because they will affect the characteristics of basaltic sediment as it is transported by wind, water, and ice, and currently we have little to no understanding as to how basaltic sediment will weather as a function of the transport mechanism and distance. We will present preliminary analyses of typical basaltic sediments that have been transported by a variety of geologic processes in Hawaii, including details about surface texture, componentry, and the influence different sedimentary processes may have on remote sensing data. The figure below shows examples of A) sediment

  8. The association between green neighborhood environments and active transportation

    EPA Science Inventory

    Background: Urban nature is an important aspect of health-promoting environments. In particular, street trees and green space can provide a low cost approach to improving public health by promoting physical activity, improving mental health, and facilitating social cohesion. Acti...

  9. Bidirectional Transport by Molecular Motors: Enhanced Processivity and Response to External Forces

    PubMed Central

    Müller, Melanie J.I.; Klumpp, Stefan; Lipowsky, Reinhard

    2010-01-01

    Abstract Intracellular transport along cytoskeletal filaments is often mediated by two teams of molecular motors that pull on the same cargo and move in opposite directions along the filaments. We have recently shown theoretically that this bidirectional transport can be understood as a stochastic tug-of-war between the two motor teams. Here, we further develop our theory to investigate the experimentally accessible dynamic behavior of cargos transported by strong motors such as kinesin-1 or cytoplasmic dynein. By studying the run and binding times of such a cargo, we show that the properties of biological motors, such as the large ratio of stall/detachment force and the small ratio of superstall backward/forward velocity, are favorable for bidirectional cargo transport, leading to fast motion and enhanced diffusion. In addition, cargo processivity is shown to be strongly enhanced by transport via several molecular motors even if these motors are engaged in a tug-of-war. Finally, we study the motility of a bidirectional cargo under force. Frictional forces arising, e.g., from the viscous cytoplasm, lead to peaks in the velocity distribution, while external forces as exerted, e.g., by an optical trap, lead to hysteresis effects. Our results, in particular our explicit expressions for the cargo binding time and the distance of the peaks in the velocity relation under friction, are directly accessible to in vitro as well as in vivo experiments. PMID:20513405

  10. A biophysical analysis of mitochondrial movement: differences between transport in neuronal cell bodies versus processes

    PubMed Central

    Narayanareddy, Babu Reddy Janakaloti; Vartiainen, Suvi; Hariri, Neema; O’Dowd, Diane K.; Gross, Steven P.

    2014-01-01

    There is increasing interest in factors that can impede cargo transport by molecular motors inside the cell. While potentially relevant (1), the importance of cargo size and sub-cellular location have received relatively little attention. Here we address these questions taking advantage of the fact that mitochondria—a common cargo—in Drosophila neurons exhibit a wide distribution of sizes. In addition, the mitochondria can be genetically marked with GFP making it possible to visualize and compare their movement in the cell bodies and processes of living cells. Using total internal reflection (TIRF) microscopy coupled with particle tracking and analysis, we quantified transport properties of GFP positive mitochondria as a function of their size and location. In neuronal cell bodies we find little evidence for significant opposition to motion, consistent with a previous study on lipid droplets (2). However, in the processes we observe an inverse relationship between mitochondrial size and velocity and run distances. This can be ameliorated via hypotonic treatment to increase process size, suggesting that motor mediated movement is impeded in this more confined environment. Interestingly, we also observe local mitochondrial accumulations in processes but not in cell bodies. Such accumulations do not completely block transport, but do increase the probability of mitochondria-mitochondria interactions. They are thus particularly interesting in relation to mitochondrial exchange of elements. PMID:24673933

  11. Multi-process herbicide transport in structured soil columns: experiments and model analysis.

    PubMed

    Köhne, J Maximilian; Köhne, Sigrid; Simůnek, Jirka

    2006-05-01

    Model predictions of pesticide transport in structured soils are complicated by multiple processes acting concurrently. In this study, the hydraulic, physical, and chemical nonequilibrium (HNE, PNE, and CNE, respectively) processes governing herbicide transport under variably saturated flow conditions were studied. Bromide (Br-), isoproturon (IPU, 3-(4-isoprpylphenyl)-1,1-dimethylurea) and terbuthylazine (TER, N2-tert-butyl-6-chloro-N4-ethyl-1,3,5-triazine-2,4-diamine) were applied to two soil columns. An aggregated Ap soil column and a macroporous, aggregated Ah soil column were irrigated at a rate of 1 cm h(-1) for 3 h. Two more irrigations at the same rate and duration followed in weekly intervals. Nonlinear (Freundlich) equilibrium and two-site kinetic sorption parameters were determined for IPU and TER using batch experiments. The observed water flow and Br- transport were inversely simulated using mobile-immobile (MIM), dual-permeability (DPM), and combined triple-porosity (DP-MIM) numerical models implemented in HYDRUS-1D, with improving correspondence between empirical data and model results. Using the estimated HNE and PNE parameters together with batch-test derived equilibrium sorption parameters, the preferential breakthrough of the weakly adsorbed IPU in the Ah soil could be reasonably well predicted with the DPM approach, whereas leaching of the strongly adsorbed TER was predicted less well. The transport of IPU and TER through the aggregated Ap soil could be described consistently only when HNE, PNE, and CNE were simultaneously accounted for using the DPM. Inverse parameter estimation suggested that two-site kinetic sorption in inter-aggregate flow paths was reduced as compared to within aggregates, and that large values for the first-order degradation rate were an artifact caused by irreversible sorption. Overall, our results should be helpful to enhance the understanding and modeling of multi-process pesticide transport through structured soils

  12. Modeling Unsaturated Flow and Transport Processes in Fractured Tuffs of Yucca Mountain

    SciTech Connect

    Wu, Yu-Shu; Lu, Guoping; Zhang, Keni; Bodvarsson, G.S.

    2003-07-15

    This paper presents a field modeling study characterizing fluid flow and tracer transport in the unsaturated zone of Yucca Mountain, Nevada, a proposed underground repository for storing high-level radioactive waste. The 500 to 700 meter thick unsaturated zone of Yucca Mountain consists of highly heterogeneous layers of anisotropic, fractured ash flow and air fall tuffs. Characterization of fluid flow and heat transfer through such a system has been a challenge due to the heterogeneities prevalent on various scales. Quantitative evaluation of water, gas, and heat flow by means of numerical simulation is essential for design and performance assessment of the repository. A three-dimensional numerical flow and transport model will be discussed. The model has been calibrated against field-measured data and takes into account the coupled processes of unsaturated flow and tracer transport in the highly heterogeneous, unsaturated fractured porous rock. The modeling approach of the model is based on a dual-continuum formulation of coupled multiphase fluid and tracer transport through fractured porous rock. As application examples, effects of current and future climates on the unsaturated zone processes are evaluated to aid in the assessment of the proposed repository's system performance.

  13. Function and repair of dental enamel - Potential role of epithelial transport processes of ameloblasts.

    PubMed

    Varga, Gábor; Kerémi, Beáta; Bori, Erzsébet; Földes, Anna

    2015-07-01

    The hardest mammalian tissue, dental enamel is produced by ameloblasts, which are electrolyte-transporting epithelial cells. Although the end product is very different, they show many similarities to transporting epithelia of the pancreas, salivary glands and kidney. Enamel is produced in a multi-step epithelial secretory process that features biomineralization which is an interplay of secreted ameloblast specific proteins and the time-specific transport of minerals, protons and bicarbonate. First, "secretory" ameloblasts form the entire thickness of the enamel layer, but with low mineral content. Then they differentiate into "maturation" ameloblasts, which remove organic matrix from the enamel and in turn further build up hydroxyapatite crystals. The protons generated by hydroxyapatite formation need to be buffered, otherwise enamel will not attain full mineralization. Buffering requires a tight pH regulation and secretion of bicarbonate by ameloblasts. The whole process has been the focus of many immunohistochemical and gene knock-out studies, but, perhaps surprisingly, no functional data existed for mineral ion transport by ameloblasts. However, recent studies including ours provided a better insight for molecular mechanism of mineral formation. The secretory regulation is not completely known as yet, but its significance is crucial. Impairing regulation retards or prevents completion of enamel mineralization and results in the development of hypomineralized enamel that easily erodes after dental eruption. Factors that impair this function are fluoride and disruption of pH regulators. Revealing these factors may eventually lead to the treatment of enamel hypomineralization related to genetic or environmentally induced malformation. PMID:25747281

  14. Recommended direct simulation Monte Carlo collision model parameters for modeling ionized air transport processes

    NASA Astrophysics Data System (ADS)

    Swaminathan-Gopalan, Krishnan; Stephani, Kelly A.

    2016-02-01

    A systematic approach for calibrating the direct simulation Monte Carlo (DSMC) collision model parameters to achieve consistency in the transport processes is presented. The DSMC collision cross section model parameters are calibrated for high temperature atmospheric conditions by matching the collision integrals from DSMC against ab initio based collision integrals that are currently employed in the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) and Data Parallel Line Relaxation (DPLR) high temperature computational fluid dynamics solvers. The DSMC parameter values are computed for the widely used Variable Hard Sphere (VHS) and the Variable Soft Sphere (VSS) models using the collision-specific pairing approach. The recommended best-fit VHS/VSS parameter values are provided over a temperature range of 1000-20 000 K for a thirteen-species ionized air mixture. Use of the VSS model is necessary to achieve consistency in transport processes of ionized gases. The agreement of the VSS model transport properties with the transport properties as determined by the ab initio collision integral fits was found to be within 6% in the entire temperature range, regardless of the composition of the mixture. The recommended model parameter values can be readily applied to any gas mixture involving binary collisional interactions between the chemical species presented for the specified temperature range.

  15. Gli2 and Gli3 Localize to Cilia and Require the Intraflagellar Transport Protein Polaris for Processing and Function

    SciTech Connect

    Michaud III, Edward J; Haycraft, Courtney J; Aydin Son, Yesim; Zhang, Qihong; Yoder, Bradley

    2005-01-01

    Intraflagellar transport (IFT) proteins are essential for cilia assembly and have recently been associated with a number of developmental processes, such as left-right axis specification and limb and neural tube patterning. Genetic studies indicate that IFT proteins are required for Sonic hedgehog (Shh)signaling downstream of the Smoothened and Patched membrane proteins but upstream of the Glioma (Gli) transcription factors. However, the role that IFT proteins play in transduction of Shh signaling and the importance of cilia in this process remain unknown. Here we provide insights into the mechanism by which defects in an IFT protein, Tg737/Polaris, affect Shh signaling in the murine limb bud. Our data show that loss of Tg737 results in altered Gli3 processing that abrogates Gli3-mediated repression of Gli1 transcriptional activity. In contrast to the conclusions drawn from genetic analysis, the activity of Gli1 and truncated forms of Gli3 (Gli3R) are unaffected in Tg737 mutants at the molecular level, indicating that Tg737/Polaris is differentially involved in specific activities of the Gli proteins. Most important, a negative regulator of Shh signaling, Suppressor of fused, and the three full-length Gli transcription factors localize to the distal tip of cilia in addition to the nucleus. Thus, our data support a model where cilia have a direct role in Gli processing and Shh signal transduction.

  16. Regulation of Human Hepatic Drug Transporter Activity and Expression by Diesel Exhaust Particle Extract

    PubMed Central

    Le Vee, Marc; Jouan, Elodie; Stieger, Bruno; Lecureur, Valérie; Fardel, Olivier

    2015-01-01

    Diesel exhaust particles (DEPs) are common environmental air pollutants primarily affecting the lung. DEPs or chemicals adsorbed on DEPs also exert extra-pulmonary effects, including alteration of hepatic drug detoxifying enzyme expression. The present study was designed to determine whether organic DEP extract (DEPe) may target hepatic drug transporters that contribute in a major way to drug detoxification. Using primary human hepatocytes and transporter-overexpressing cells, DEPe was first shown to strongly inhibit activities of the sinusoidal solute carrier (SLC) uptake transporters organic anion-transporting polypeptides (OATP) 1B1, 1B3 and 2B1 and of the canalicular ATP-binding cassette (ABC) efflux pump multidrug resistance-associated protein 2, with IC50 values ranging from approximately 1 to 20 μg/mL and relevant to environmental exposure situations. By contrast, 25 μg/mL DEPe failed to alter activities of the SLC transporter organic cation transporter (OCT) 1 and of the ABC efflux pumps P-glycoprotein and bile salt export pump (BSEP), whereas it only moderately inhibited those of sodium taurocholate co-transporting polypeptide and of breast cancer resistance protein (BCRP). Treatment by 25 μg/mL DEPe was next demonstrated to induce expression of BCRP at both mRNA and protein level in cultured human hepatic cells, whereas it concomitantly repressed mRNA expression of various transporters, including OATP1B3, OATP2B1, OCT1 and BSEP. Such changes in transporter expression were found to be highly correlated to those caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a reference activator of the aryl hydrocarbon receptor (AhR) pathway. This suggests that DEPe, which is enriched in known ligands of AhR like polycyclic aromatic hydrocarbons, alters drug transporter expression via activation of the AhR cascade. Taken together, these data established human hepatic transporters as targets of organic chemicals containing in DEPs, which may contribute to their

  17. Regulation of human hepatic drug transporter activity and expression by diesel exhaust particle extract.

    PubMed

    Le Vee, Marc; Jouan, Elodie; Stieger, Bruno; Lecureur, Valérie; Fardel, Olivier

    2015-01-01

    Diesel exhaust particles (DEPs) are common environmental air pollutants primarily affecting the lung. DEPs or chemicals adsorbed on DEPs also exert extra-pulmonary effects, including alteration of hepatic drug detoxifying enzyme expression. The present study was designed to determine whether organic DEP extract (DEPe) may target hepatic drug transporters that contribute in a major way to drug detoxification. Using primary human hepatocytes and transporter-overexpressing cells, DEPe was first shown to strongly inhibit activities of the sinusoidal solute carrier (SLC) uptake transporters organic anion-transporting polypeptides (OATP) 1B1, 1B3 and 2B1 and of the canalicular ATP-binding cassette (ABC) efflux pump multidrug resistance-associated protein 2, with IC50 values ranging from approximately 1 to 20 μg/mL and relevant to environmental exposure situations. By contrast, 25 μg/mL DEPe failed to alter activities of the SLC transporter organic cation transporter (OCT) 1 and of the ABC efflux pumps P-glycoprotein and bile salt export pump (BSEP), whereas it only moderately inhibited those of sodium taurocholate co-transporting polypeptide and of breast cancer resistance protein (BCRP). Treatment by 25 μg/mL DEPe was next demonstrated to induce expression of BCRP at both mRNA and protein level in cultured human hepatic cells, whereas it concomitantly repressed mRNA expression of various transporters, including OATP1B3, OATP2B1, OCT1 and BSEP. Such changes in transporter expression were found to be highly correlated to those caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a reference activator of the aryl hydrocarbon receptor (AhR) pathway. This suggests that DEPe, which is enriched in known ligands of AhR like polycyclic aromatic hydrocarbons, alters drug transporter expression via activation of the AhR cascade. Taken together, these data established human hepatic transporters as targets of organic chemicals containing in DEPs, which may contribute to their

  18. Chronic methylphenidate alters locomotor activity and dopamine transporters differently from cocaine.

    PubMed

    Izenwasser, S; Coy, A E; Ladenheim, B; Loeloff, R J; Cadet, J L; French, D

    1999-06-01

    Continuous infusion of cocaine produces partial behavioral tolerance to its locomotor activating effects, while daily injections produce sensitization. Methylphenidate binds with a similar affinity to cocaine at the dopamine transporter, but has a much lower affinity for the serotonin transporter than does cocaine. This study was done to compare the effects of chronic methylphenidate with chronic cocaine. The pattern of locomotor activity over a 7 day treatment period was significantly different from cocaine. Methylphenidate elevated activity on each day, compared to saline, yet neither tolerance to a continuous infusion of the drug, nor sensitization to repeated daily injections was produced. We have previously shown that neither of these treatments with cocaine produces significant alterations in dopamine transporter density 1 day after the end of treatment. In contrast, methylphenidate injections significantly decreased dopamine transporters in rostral caudate putamen, with no change in nucleus accumbens. Continuous infusion of methylphenidate had no effect on dopamine transporters in either brain region. These findings provide further evidence that different classes of dopamine uptake inhibitors may interact with the dopamine transporter in qualitatively different manners. Furthermore, it is possible that the inhibition of serotonin uptake by cocaine may contribute to the adaptations in behavioral activity that are seen during chronic treatment. PMID:10414438

  19. Metronidazole activation and isolation of Clostridium acetobutylicum electron transport genes.

    PubMed Central

    Santangelo, J D; Jones, D T; Woods, D R

    1991-01-01

    An Escherichia coli F19 recA, nitrate reductase-deficient mutant was constructed by transposon mutagenesis and shown to be resistant to metronidazole. This mutant was a most suitable host for the isolation of Clostridium acetobutylicum genes on recombinant plasmids, which activated metronidazole and rendered the E. coli F19 strain sensitive to metronidazole. Twenty-five E. coli F19 clones containing different recombinant plasmids were isolated and classified into five groups on the basis of their sensitivity to metronidazole. The clones were tested for nitrate reductase, pyruvate-ferredoxin oxidoreductase, and hydrogenase activities. DNA hybridization and restriction endonuclease mapping revealed that four of the C. acetobutylicum insert DNA fragments on recombinant plasmids were linked in an 11.1-kb chromosomal fragment. DNA sequencing and amino acid homology studies indicated that this DNA fragment contained a flavodoxin gene which encoded a protein of 160 amino acids that activated metronidazole and made the E. coli F19 mutant very sensitive to metronidazole. The flavodoxin and hydrogenase genes which are involved in electron transfer systems were linked on the 11.1-kb DNA fragment from C. acetobutylicum. Images PMID:1991710

  20. Heat Transfer Processes for the Thermal Energy Balance of Organisms. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Stevenson, R. D.

    This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module describes heat transfer processes involved in the exchange of heat…

  1. Loads and Transport Processes of Nutrients and Pesticides in Five Agricultural Watersheds

    NASA Astrophysics Data System (ADS)

    Domagalski, J. L.; Ator, S. W.; Lampe, D. C.; Baker, N. T.; Sandstrom, M. W.; Coupe, R. H.; Dileanis, P. D.

    2006-05-01

    A comparative study of five agricultural watersheds spanning a range of climatic and hydrologic conditions was completed as part of a larger study on the transport of nutrients and pesticides in multiple environmental compartments of small watersheds. Attention was given to the role of the unsaturated zone, ground water, the ground-water/surface-water interface, overland flow, and rain to account for the loads and to determine which compounds move through the environment in similar ways. In ephemeral streams, with little or no connection to shallow ground water such as in semi-arid settings, most of the chemical transport occurs following precipitation events. In contrast, some heavily irrigated agricultural watersheds, also in semi-arid environments but where the source of irrigation water is imported surface water, experience increases in ground-water levels and year-round stream flow as a result of ground water discharge to the stream through either the stream bed or through seeps (base flow). In those systems, total nitrogen is likely to be the most important agricultural compound with respect to the annual load, while pesticide transport may be minimal. Streams with a combination of base flow and substantial overland flow are more likely to transport significant quantities of phosphorus and pesticides relative to streams dominated by ground-water base flow. Streams fed by other subsurface processes, such as discharge from tile drains, are more like the ground-water base-flow-dominated systems with respect to nitrogen, phosphorus, and pesticides. In most cases, overland flow processes transport the greatest amount of unaltered pesticide compounds. However, some pesticide degradates, such as the daughter products of atrazine and metolachlor, are transported more effectively, or accumulate to a greater degree, in the unsaturated zone and ground water relative to the parent compounds, and a substantial amount of the annual load is contributed by ground water. Rain

  2. Workshop on Critical Issues in Microgravity Fluids, Transport, and Reaction Processes in Advanced Human Support Technology

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Francis P.; Joshi, Jitendra A.

    2004-01-01

    This workshop was designed to bring the experts from the Advanced Human Support Technologies communities together to identify the most pressing and fruitful areas of research where success hinges on collaborative research between the two communities. Thus an effort was made to bring together experts in both advanced human support technologies and microgravity fluids, transport and reaction processes. Expertise was drawn from academia, national laboratories, and the federal government. The intent was to bring about a thorough exchange of ideas and develop recommendations to address the significant open design and operation issues for human support systems that are affected by fluid physics, transport and reaction processes. This report provides a summary of key discussions, findings, and recommendations.

  3. Investigation of the Physical Processes Governing Large-scale Tracer Transport in the Stratosphere and Troposphere

    NASA Technical Reports Server (NTRS)

    Selkirk, Henry B.

    1996-01-01

    This report reviews the second year of a three-year research program to investigate the physical mechanisms which underlie the transport of trace constituents in the stratosphere- troposphere system. The primary scientific goal of the research is to identify the processes which transport air masses within the lower stratosphere, particularly between the tropics and middle latitudes. The SASS program seeks to understand the impact of the present and future fleets of conventional jet traffic on the upper troposphere and lower stratosphere, while complementary airborne observations under UARP seek to understand the complex interactions of dynamical and chemical processes that affect the ozone layer. The present investigation contributes to the goals of each of these by diagnosing the history of air parcels intercepted by NASA research aircraft in UARP and AEAP campaigns.

  4. The Effect of an Active Transport to School Intervention at a Suburban Elementary School

    ERIC Educational Resources Information Center

    Bungum, Timothy J.; Clark, Sheila; Aguilar, Brenda

    2014-01-01

    Background: Many children do not meet physical activity (PA) guidelines. One strategy that may enhance PA is to increase active transport to school (ATS) rates. Purpose: To assess the effects of an ATS intervention. Methods: A quasi-experimental design was used to compare ATS and vehicle traffic rates at a school that participated in a statewide…

  5. Policies Related to Active Transport to and from School: A Multisite Case Study

    ERIC Educational Resources Information Center

    Eyler, Amy A.; Brownson, Ross C.; Doescher, Mark P.; Evenson, Kelly R.; Fesperman, Carrie E.; Litt, Jill S.; Pluto, Delores; Steinman, Lesley E.; Terpstra, Jennifer L.; Troped, Philip J.; Schmid, Thomas L.

    2008-01-01

    Active transportation to and from school (ATS) is a viable strategy to help increase physical activity among youth. ATS can be challenging because initiatives require transdisciplinary collaboration, are influenced by the built environment and are affected by numerous policies. The purpose of this study is to identify policies and factors that…

  6. The co-benefits for health of investing in active transportation.

    PubMed

    Giles-Corti, Billie; Foster, Sarah; Shilton, Trevor; Falconer, Ryan

    2010-01-01

    Amid growing concerns about the impact of rising obesity and physical inactivity levels, climate change, population growth, increasing traffic congestion and declining oil supplies, multiple sectors are now promoting active transportation as an alternative to driving. This paper considers the health benefits and co-benefits of investing in active transportation, enabling comparison of policy options to optimise societal objectives aimed at creating healthy, socially and environmentally sustainable communities. Policies promoting the use of both energy-efficient motor vehicles and increased active transportation would almost double the impact on greenhouse gas emissions and would reduce disease burden by increasing physical activity. More co-benefit and economic analyses research is required to inform 'joined-up' policy solutions. PMID:20637168

  7. A numerical method for the time coarsening of transport processes at the atomistic scale

    NASA Astrophysics Data System (ADS)

    Gonzalez-Ferreiro, B.; Romero, I.; Ortiz, M.

    2016-05-01

    We propose a novel numerical scheme for the simulation of slow transport processes at the atomistic scale. The scheme is based on a model for non-equilibrium statistical thermodynamics recently proposed by the authors, and extends it by formulating a variational integrator, i.e. a discrete functional whose optimality conditions provide all the governing equations of the problem. The method is employed to study surface segregation of AuAg alloys and its convergence is confirmed numerically.

  8. Barotropic and baroclinic processes in the transport variability of the Antarctic Circumpolar Current

    NASA Astrophysics Data System (ADS)

    Olbers, Dirk; Lettmann, Karsten

    2007-12-01

    Synoptic scale variability of the Southern Ocean wind field in the high-frequency range of barotropic Rossby waves results in transport variations of the Antarctic Circumpolar Current (ACC), which are highly coherent with the bottom pressure field all around the Antarctic continent. The coherence pattern, in contrast to the steady state ACC, is steered by the geostrophic f/ h contours passing through Drake Passage and circling closely around the continent. At lower frequencies, with interannual and decadal periods, the correlation with the bottom pressure continues, but baroclinic processes gain importance. For periods exceeding a few years, variations of the ACC transport are in geostrophic balance with the pressure field associated with the baroclinic potential energy stored in the stratification, whereas bottom pressure plays a minor role. The low-frequency variability of the ACC transport is correlated with the baroclinic state variable in the entire Southern Ocean, mediated by baroclinic topographic-planetary Rossby waves that are not bound to f/ h contours. To clarify the processes of wave dynamics and pattern correlation, we apply a circulation model with simplified physics (the barotropic-baroclinic-interaction model BARBI) and use two types of wind forcing: the National Centers for Environmental Prediction (NCEP) wind field with integrations spanning three decades and an artificial wind field constructed from the first three empirical orthogonal functions of NCEP combined with a temporal variability according to an autoregressive process. Experiments with this Southern Annular Mode type forcing have been performed for 1,800 years. We analyze the spin-up, trends, and variability of the model runs. Particular emphasis is placed on coherence and correlation patterns between the ACC transport, the wind forcing, the bottom pressure field and the pressure associated with the baroclinic potential energy. A stochastic dynamical model is developed that describes

  9. Process of activation of a palladium catalyst system

    DOEpatents

    Sobolevskiy, Anatoly; Rossin, Joseph A.; Knapke, Michael J.

    2011-08-02

    Improved processes for activating a catalyst system used for the reduction of nitrogen oxides are provided. In one embodiment, the catalyst system is activated by passing an activation gas stream having an amount of each of oxygen, water vapor, nitrogen oxides, and hydrogen over the catalyst system and increasing a temperature of the catalyst system to a temperature of at least 180.degree. C. at a heating rate of from 1-20.degree./min. Use of activation processes described herein leads to a catalyst system with superior NOx reduction capabilities.

  10. Built Environment and Active Transport to School (BEATS) Study: protocol for a cross-sectional study

    PubMed Central

    Mandic, Sandra; Williams, John; Moore, Antoni; Hopkins, Debbie; Flaherty, Charlotte; Wilson, Gordon; García Bengoechea, Enrique; Spence, John C

    2016-01-01

    Introduction Active transport to school (ATS) is a convenient way to increase physical activity and undertake an environmentally sustainable travel practice. The Built Environment and Active Transport to School (BEATS) Study examines ATS in adolescents in Dunedin, New Zealand, using ecological models for active transport that account for individual, social, environmental and policy factors. The study objectives are to: (1) understand the reasons behind adolescents and their parents' choice of transport mode to school; (2) examine the interaction between the transport choices, built environment, physical activity and weight status in adolescents; and (3) identify policies that promote or hinder ATS in adolescents. Methods and analysis The study will use a mixed-method approach incorporating both quantitative (surveys, anthropometry, accelerometers, Geographic Information System (GIS) analysis, mapping) and qualitative methods (focus groups, interviews) to gather data from students, parents, teachers and school principals. The core data will include accelerometer-measured physical activity, anthropometry, GIS measures of the built environment and the use of maps indicating route to school (students)/work (parents) and perceived safe/unsafe areas along the route. To provide comprehensive data for understanding how to change the infrastructure to support ATS, the study will also examine complementary variables such as individual, family and social factors, including student and parental perceptions of walking and cycling to school, parental perceptions of different modes of transport to school, perceptions of the neighbourhood environment, route to school (students)/work (parents), perceptions of driving, use of information communication technology, reasons for choosing a particular school and student and parental physical activity habits, screen time and weight status. The study has achieved a 100% school recruitment rate (12 secondary schools). Ethics and

  11. Students' Learning Activities While Studying Biological Process Diagrams

    NASA Astrophysics Data System (ADS)

    Kragten, Marco; Admiraal, Wilfried; Rijlaarsdam, Gert

    2015-08-01

    Process diagrams describe how a system functions (e.g. photosynthesis) and are an important type of representation in Biology education. In the present study, we examined students' learning activities while studying process diagrams, related to their resulting comprehension of these diagrams. Each student completed three learning tasks. Verbal data and eye-tracking data were collected as indications of students' learning activities. For the verbal data, we applied a fine-grained coding scheme to optimally describe students' learning activities. For the eye-tracking data, we used fixation time and transitions between areas of interest in the process diagrams as indices of learning activities. Various learning activities while studying process diagrams were found that distinguished between more and less successful students. Results showed that between-student variance in comprehension score was highly predicted by meaning making of the process arrows (80%) and fixation time in the main area (65%). Students employed successful learning activities consistently across learning tasks. Furthermore, compared to unsuccessful students, successful students used a more coherent approach of interrelated learning activities for comprehending process diagrams.

  12. [Monitoring of water and salt transport in silt and sandy soil during the leaching process].

    PubMed

    Fu, Teng-Fei; Jia, Yong-Gang; Guo, Lei; Liu, Xiao-Lei

    2012-11-01

    Water and salt transport in soil and its mechanism is the key point of the saline soil research. The dynamic rule of water and transport in soil during the leaching process is the theoretical basis of formation, flush, drainage and improvement of saline soil. In this study, a vertical infiltration experiment was conducted to monitor the variation in the resistivity of silt and sandy soil during the leaching process by the self-designed automatic monitoring device. The experimental results showed that the peaks in the resistivity of the two soils went down and faded away in the course of leaching. It took about 30 minutes for sandy soil to reach the water-salt balance, whereas the silt took about 70 minutes. With the increasing leaching times, the desalination depth remained basically the same, being 35 cm for sandy soil and 10 cm for the silt from the top to bottom of soil column. Therefore, 3 and 7 leaching processes were required respectively for the complete desalination of the soil column. The temporal and spatial resolution of this monitoring device can be adjusted according to the practical demand. This device can not only achieve the remote, in situ and dynamic monitoring data of water and salt transport, but also provide an effective method in monitoring, assessment and early warning of salinization. PMID:23323426

  13. New Potentiometric Wireless Chloride Sensors Provide High Resolution Information on Chemical Transport Processes in Streams

    NASA Astrophysics Data System (ADS)

    Smettem, Keith; Harris, Nick; Cranny, Andy; Klaus, Julian; Pfister, Laurent

    2016-04-01

    Quantifying the travel times, pathways and dispersion of solutes moving through stream environments is critical for understanding the biogeochemical cycling processes that control ecosystem functioning. Validation of stream solute transport and exchange process models requires data obtained from in-stream measurement of chemical concentration changes through time. This can be expensive and time consuming, leading to a need for cheap distributed sensor arrays that respond instantly and record chemical transport at points of interest on timescales of seconds. To meet this need we apply new, low-cost (in the order of a euro per sensor) potentiometric chloride sensors used in a distributed array to obtain data with high spatial and temporal resolution. The application here is to monitoring in-stream hydrodynamic transport and dispersive mixing of an injected chemical, in this case NaCl. We present data obtained from the distributed sensor array under baseflow conditions for three stream reaches in Luxembourg. Sensor results are comparable to data obtained from more expensive electrical conductivity meters and allow spatial resolution of hydrodynamic mixing processes and identification of chemical 'dead zones' in the study reaches.

  14. Hydrologic Processes Controlling the Transport of Radionuclides Through the Hanford Vadose Zone

    NASA Astrophysics Data System (ADS)

    Mayes, M. A.; Jardine, P. M.; Pace, M. N.; Fendorf, S. E.; Mehlhorn, T. L.; Roh, Y.; Ladd, J. L.; Bjornstad, B. N.

    2001-12-01

    At the U.S. Department of Energy's Hanford Reservation in south central Washington, accelerated migration of radionuclides has been observed in the vadose zone beneath the Hanford Tank Farms. The goal of this research was to provide an improved understanding and predictive capability of the coupled hydrological and geochemical mechanisms that are responsible for contaminant mobility in the vadose zone. The research strategy consisted of collecting undisturbed sediment cores (0.3 m diameter x 0.3 m length) in order to perform laboratory-scale, multiple nonreactive and reactive transport experiments at a variety of different water contents. Cores were collected from the Miocene-Pliocene age Upper Ringold Formation, which consists of fine sand, silt and clay. Cores were acquired both parallel and perpendicular to bedding. Two units within the U. Ringold were sampled, a horizontally-bedded, laminated Upper Silt and a cross-bedded Lower Silty Sand. Unsaturated transport experiments were performed using the nonreactive tracers Br-, PFBA, and PIPES, which differ in their free-water molecular diffusion coefficients. Unsaturated transport experiments through cores with discontinuous layering resulted in the formation of an unstable wetting front characterized by preferential finger flow and the development of zones of perched water. Media bypass is inferred by early breakthrough of tracers relative to saturated flow, while the presence of perched water is suggested by decreasing core matric potential. Further, observed separation of tracers (Br-> PFBA > PIPES) suggests that diffusional processes can contribute to contaminant transport. Conversely, transport through cores composed of laterally continuous beds did not result in preferential flow, the development of perched water, or tracer separation regardless of saturation. This suggests a propensity for lateral flow beneath the tank farms. Preferential vertical finger flow may be initiated by intersection with lithologic

  15. Dissection of Photosynthetic Electron Transport Process in Sweet Sorghum under Heat Stress

    PubMed Central

    Yan, Kun; Chen, Peng; Shao, Hongbo; Shao, Chuyang; Zhao, Shijie; Brestic, Marian

    2013-01-01

    Plant photosynthesis and photosystem II (PSII) are susceptible to high temperature. However, photosynthetic electron transport process under heat stress remains unclear. To reveal this issue, chlorophyll a fluorescence and modulated 820 nm reflection were simultaneously detected in sweet sorghum. At 43°C, J step in the chlorophyll a fluorescence transient was significantly elevated, suggesting that electron transport beyond primary quinone of PSII (QA) (primary quinone electron acceptor of PSII) was inhibited. PSI (Photosystem I) photochemical capacity was not influenced even under severe heat stress at 48°C. Thus, PSI oxidation was prolonged and PSI re-reduction did not reach normal level. The inhibition of electron transport between PSII and PSI can reduce the possibility of PSI photoinhibition under heat stress. PSII function recovered entirely one day after heat stress at 43°C, implying that sweet sorghum has certain self-remediation capacity. When the temperature reached 48°C, the maximum quantum yield for primary photochemistry and the electron transport from PSII donor side were remarkably decreased, which greatly limited the electron flow to PSI, and PSI re-reduction suspended. The efficiency of an electron transferred from the intersystem electron carrier (plastoquinol, PQH2) to the end electron acceptors at the PSI acceptor side increased significantly at 48°C, and the reason was the greater inhibition of electron transport before PQH2. Thus, the fragment from QA to PQH2 is the most heat sensitive in the electron transport chain between PSII and PSI in sweet sorghum. PMID:23717388

  16. Tau reduction prevents Aβ-induced axonal transport deficits by blocking activation of GSK3β

    PubMed Central

    Xu, Jordan C.; Fomenko, Vira; Miyamoto, Takashi; Suberbielle, Elsa; Knox, Joseph A.; Ho, Kaitlyn; Kim, Daniel H.; Yu, Gui-Qiu

    2015-01-01

    Axonal transport deficits in Alzheimer’s disease (AD) are attributed to amyloid β (Aβ) peptides and pathological forms of the microtubule-associated protein tau. Genetic ablation of tau prevents neuronal overexcitation and axonal transport deficits caused by recombinant Aβ oligomers. Relevance of these findings to naturally secreted Aβ and mechanisms underlying tau’s enabling effect are unknown. Here we demonstrate deficits in anterograde axonal transport of mitochondria in primary neurons from transgenic mice expressing familial AD-linked forms of human amyloid precursor protein. We show that these deficits depend on Aβ1–42 production and are prevented by tau reduction. The copathogenic effect of tau did not depend on its microtubule binding, interactions with Fyn, or potential role in neuronal development. Inhibition of neuronal activity, N-methyl-d-aspartate receptor function, or glycogen synthase kinase 3β (GSK3β) activity or expression also abolished Aβ-induced transport deficits. Tau ablation prevented Aβ-induced GSK3β activation. Thus, tau allows Aβ oligomers to inhibit axonal transport through activation of GSK3β, possibly by facilitating aberrant neuronal activity. PMID:25963821

  17. Identification of transport processes in Southern Indian fractured crystalline rock using forced-gradient tracer experiments

    NASA Astrophysics Data System (ADS)

    Guihéneuf, Nicolas; Bour, Olivier; Boisson, Alexandre; Le Borgne, Tanguy; Becker, Matthew R.; Nigon, Benoit; Wajiduddin, Mohammed; Ahmed, Shakeel; Maréchal, Jean-Christophe

    2015-04-01

    Understanding dominant transport processes is essential to improve prediction of contaminants transfer in fractured crystalline rocks. In such fractured media, solute transport is characterized by fast advection within open and connected fractures and sometimes by matrix diffusion that may be enhanced by chemical weathering. To investigate this phenomenon, we carried out radially convergent and push-pull tracer experiments in the fractured granite of the Experimental Hydrogeological Park of Choutuppal (Southern India). Tracer tests were performed in the same permeable fracture from few meters to several ten meters and from few hours to two weeks to check the consistency of the results at different spatial and temporal scales. These different types of forced gradient tracer experiments allow separation of the effects of advection and diffusion on transport. Breakthrough curves from radially convergent tracer tests display systematically a -2 power law slope on the late time behavior. This tailing can be adequately represented by a transport model that only takes into account heterogeneous advection caused by fluid flow channeling. The negligible impact of matrix diffusion was confirmed by the push-pull tracer tests, at least for the duration of experiments. A push-pull experiment carried out with a cocktail of two conservative tracers having different diffusion coefficients displayed similar breakthrough curves. Increasing the resting phase during the experiments did not lead to a significant decline of peak concentration. All these results suggest a negligible impact of matrix diffusion. However, increasing the scales of investigation during push-pull tracer tests led to a decrease of the power law slope on the late time behavior. This behavior that cannot be modeled with a transport model based on independent flow paths and indicate non-reversible heterogeneous advection. This process could be explained by the convergence of streamlines after a certain distance

  18. Advanced bulk processing of lightweight materials for utilization in the transportation sector

    NASA Astrophysics Data System (ADS)

    Milner, Justin L.

    The overall objective of this research is to develop the microstructure of metallic lightweight materials via multiple advanced processing techniques with potentials for industrial utilization on a large scale to meet the demands of the aerospace and automotive sectors. This work focused on (i) refining the grain structure to increase the strength, (ii) controlling the texture to increase formability and (iii) directly reducing processing/production cost of lightweight material components. Advanced processing is conducted on a bulk scale by several severe plastic deformation techniques including: accumulative roll bonding, isolated shear rolling and friction stir processing to achieve the multiple targets of this research. Development and validation of the processing techniques is achieved through wide-ranging experiments along with detailed mechanical and microstructural examination of the processed material. On a broad level, this research will make advancements in processing of bulk lightweight materials facilitating industrial-scale implementation. Where accumulative roll bonding and isolated shear rolling, currently feasible on an industrial scale, processes bulk sheet materials capable of replacing more expensive grades of alloys and enabling low-temperature and high-strain-rate formability. Furthermore, friction stir processing to manufacture lightweight tubes, made from magnesium alloys, has the potential to increase the utilization of these materials in the automotive and aerospace sectors for high strength - high formability applications. With the increased utilization of these advanced processing techniques will significantly reduce the cost associated with lightweight materials for many applications in the transportation sectors.

  19. Hold My Calls: An Activity for Introducing the Statistical Process

    ERIC Educational Resources Information Center

    Abel, Todd; Poling, Lisa

    2015-01-01

    Working with practicing teachers, this article demonstrates, through the facilitation of a statistical activity, how to introduce and investigate the unique qualities of the statistical process including: formulate a question, collect data, analyze data, and interpret data.

  20. Rebuilding cytoskeleton roads: Active-transport-induced polarization of cells

    NASA Astrophysics Data System (ADS)

    Hawkins, R. J.; Bénichou, O.; Piel, M.; Voituriez, R.

    2009-10-01

    Many cellular processes require a polarization axis which generally initially emerges as an inhomogeneous distribution of molecular markers in the cell. We present a simple analytical model of a general mechanism of cell polarization taking into account the positive feedback due to the coupled dynamics of molecular markers and cytoskeleton filaments. We find that the geometry of the organization of cytoskeleton filaments, nucleated on the membrane (e.g., cortical actin) or from a center in the cytoplasm (e.g., microtubule asters), dictates whether the system is capable of spontaneous polarization or polarizes only in response to external asymmetric signals. Our model also captures the main features of recent experiments of cell polarization in two considerably different biological systems, namely, mating budding yeast and neuron growth cones.

  1. Multidrug efflux transporter activity in sea urchin embryos:Does localization provide a diffusive advantage?

    NASA Astrophysics Data System (ADS)

    Song, Xianfeng; Setayeshgar, Sima; Cole, Bryan; Hamdoun, Amro; Epel, David

    2008-03-01

    Experiments have shown upregulation of multidrug efflux transporter activity approximately 30 min after fertilization in the sea urchin embryo [1]. These ATP-hydrolyzing transporter proteins pump moderately hydrophobic molecules out of the cell and represent the cell's first line of defense againstexogenous toxins. It has also been shown that transporters are moved in vesicles along microfilaments and localized to tips of microvilli prior to activation. We have constructed a geometrically realistic model of the embryo, including microvilli, to explore the functional role of this localization in the efficient elimination of toxins from the standpoint of diffusion. We compute diffusion of toxins in extracellular, membrane and intracellular spaces coupled with transporter activity, using experimentally derived values for physical parameters. For transporters uniformly distributed along microvilli and tip-localized transporters we compare regions in parameter space where each distribution provides diffusive advantage, and comment on the physically expected conditions. [1] A. M. Hamdoun, G. N. Cherr, T. A. Roepke and D. Epel, Developmental Biology 276 452 (2004).

  2. High liquid fuel yielding biofuel processes and a roadmap for the future transportation

    NASA Astrophysics Data System (ADS)

    Singh, Navneet R.

    In a fossil-fuel deprived world when crude oil will be scarce and transportation need cannot be met with electricity and transportation liquid fuel must be produced, biomass derived liquid fuels can be a natural replacement. However, the carbon efficiency of the currently known biomass to liquid fuel conversion processes ranges from 35-40%, yielding 90 ethanol gallon equivalents (ege) per ton of biomass. This coupled with the fact that the efficiency at which solar energy is captured by biomass (<1%) is significantly lower than H 2 (10-27%) and electricity (20-42%), implies that sufficient land area is not available to meet the need for the entire transportation sector. To counter this dilemma, a number of processes have been proposed in this work: a hybrid hydrogen-carbon (H2CAR) process based on biomass gasification followed by the Fischer-Tropsch process such that 100% carbon efficiency is achieved yielding 330 ege/ton biomass using hydrogen derived from a carbon-free energy. The hydrogen requirement for the H2CAR process is 0.33 kg/liter of diesel. To decrease the hydrogen requirement associated with the H2CAR process, a hydrogen bio-oil (H2Bioil) process based on biomass fast-hydropyrolysis/hydrodeoxygenation is proposed which can achieve liquid fuel yield of 215 ege/ton consuming 0.11 kg hydrogen per liter of oil. Due to the lower hydrogen consumption of the H2Bioil process, synergistically integrated transition pathways are feasible where hot syngas derived from coal gasification (H2Bioil-C) or a natural gas reformer (H 2Bioil-NG) is used to supply the hydrogen and process heat for the biomass fast-hydropyrolysis/hydrodeoxygenation. Another off-shoot of the H2Bioil process is the H2Bioil-B process, where hydrogen required for the hydropyrolysis is obtained from gasification of a fraction of the biomass. H2Bioil-B achieves the highest liquid fuel yield (126-146 ege/ton of biomass) reported in the literature for any self-contained conversion of biomass to

  3. Importin-mediated retrograde transport of CREB2 from distal processes to the nucleus in neurons

    PubMed Central

    Lai, Kwok-On; Zhao, Yali; Ch'ng, Toh Hean; Martin, Kelsey C.

    2008-01-01

    Signals received at distal synapses of neurons must be conveyed to the nucleus to initiate the changes in transcription that underlie long-lasting synaptic plasticity. The presence of importin nuclear transporters and of select transcription factors at synapses raises the possibility that importins directly transport transcription factors from synapse to nucleus to modulate gene expression. Here, we show that cyclic AMP response element binding protein 2 (CREB2)/activating transcription factor 4 (ATF4), a transcriptional repressor that modulates long-term synaptic plasticity and memory, localizes to distal dendrites of rodent hippocampal neurons and neurites of Aplysia sensory neurons (SNs) and binds to specific importin α isoforms. Binding of CREB2 to importin α is required for its transport from distal dendrites to the soma and for its translocation into the nucleus. CREB2 accumulates in the nucleus during long-term depression (LTD) but not long-term potentiation of rodent hippocampal synapses, and during LTD but not long-term facilitation (LTF) of Aplysia sensory-motor synapses. Time-lapse microscopy of CREB2 tagged with a photoconvertible fluorescent protein further reveals retrograde transport of CREB2 from distal neurites to the nucleus of Aplysia SN during phenylalanine-methionine-arginine-phenylalanine-amide (FMRFamide)-induced LTD. Together, our findings indicate that CREB2 is a novel cargo of importin α that translocates from distal synaptic sites to the nucleus after stimuli that induce LTD of neuronal synapses. PMID:18957537

  4. Biochemical activities in soil overlying Paraho processed oil shale

    SciTech Connect

    Sorensen, D.L.

    1982-01-01

    Microbial activity development in soil materials placed over processed oil shale is vital to the plant litter decomposition, cycling of nutrients, and soil organic matter accumulation and maintenance. Samples collected in the summers of 1979, 1980, and 1981 from revegetated soil 30-, 61-, and 91-cm deep overlying spent oil shale in the Piceance Basin of northwestern Colorado were assayed for dehydrogenease activity with glucose and without glucose, for phosphatase activity, and for acetylene reduction activity. Initial ammonium and nitrite nitrogen oxidation rates and potential denitrification rates were determined in 1981. Zymogenous dehydrogenase activity, phosphatase activity, nitrogenase activity, potential denitrification rates, and direct microscopic counts were lower in surface soil 30 cm deep, and were frequently lower in surface soil 61 cm deep over processed shale than in a surface-disturbed control area soil. Apparently, microbial activities are stressed in these more shallow replaced soils. Soil 61 cm deep over a coarse-rock capillary barrier separating the soil from the spent shale, frequently had improved biochemical activity. Initial ammonium and nitrite nitrogen oxidation rates were lower in all replaced soils than in the disturbed control soil. Soil core samples taken in 1981 were assayed for dehydrogenase and phosphatase activities, viable bacteria, and viable fungal propagules. In general, microbial activity decreased quickly below the surface. At depths greater than 45 cm, microbial activities were similar in buried spent shale and surface-disturbed control soil.

  5. Transport processes and distribution of plasma in the ionosphere during total solar eclipses

    NASA Astrophysics Data System (ADS)

    Chukwuma, Victor

    2016-07-01

    The effect of solar eclipse on the ionospheric F2 layer does not appear to depend only on the changes in the electron density. In this regards therefore, we have investigated the transport term process and the distribution F2 plasma during three total solar eclipses (TSE) at low- and mid-latitude. Particularly, the diurnal changes in the NmF2 and hmF2 during these spectacular events, as recorded by the ionosondes situated along the path of solar eclipses, which are within the obscuration percentage of 59-90% were investigated. Presently, our results show that NmF2 decreased during the eclipse window, as a consequence of the variation in the local solar radiation in regions under investigation. However, at mid-latitude, the distribution of F2 plasma was dominated by diffusion mechanisms which determined the height at which the F2 peak formed and were related to the changes in thermospheric composition. While at low-latitude the plasma distribution during TSE appeared to depend on combined effect of solar ionizing radiation (SIR) and the background nighttime ionospheric instabilities/irregularities mechanism. The downward/upward transport processes of the plasma appear to correspond with the drifting of the diffusion mechanisms and suffered a comparable variation with the SIR. Furthermore, at low-latitude ionosphere the transport process is controlled by the equatorial electric field. It is also observed that the eastward/westward movement of the equatorial electric field during the eclipse phase was connected to the upward/downward movement of the vertical transport. In conclusion, our results appear to indicate that eclipse effects increased with increase in latitude and the time lag decreases with increase in latitude.

  6. A coupling kinetics model for pollutant release and transport in the process of landfill settlement.

    PubMed

    Zhao, Ying; Xue, Qiang; Liu, Lei

    2012-10-01

    A coupling kinetics model is developed to simulate the release and transport of landfill leachate pollutants in a deformable municipal solid waste landfill by taking into account of landfill settlement, seepage of leachate water, hydrolyse of insoluble and degradable organic pollutants in solid phase, biodegradation of soluble and degradable organic pollutants in solid phase and aqueous one, growth of aerobic and anaerobic microorganism, and consumption of dissolved oxygen. The release and transport of organic pollutants and microorganisms in landfills in the process of landfill settlement was simulated by considering no hydraulic effect. Simulation results demonstrated that the interaction between landfill settlement and the release, transport and biodegradation of landfill leachate pollutants was significant. Porosity and saturated hydraulic conductivity were not constants because of the landfill settlement, which affected the release, transport and biodegradation of landfill leachate pollutants, and furthermore acted on the landfill settlement. The simulation results accorded with the practical situation, which preliminarily verified the reliability of the mathematical model and the numerical program in this paper. PMID:23202755

  7. Ozone seasonality above the tropical tropopause: reconciling the Eulerian and Lagrangian perspectives of transport processes

    NASA Astrophysics Data System (ADS)

    Abalos, M.; Ploeger, F.; Konopka, P.; Randel, W. J.; Serrano, E.

    2013-11-01

    We aim to reconcile the recently published, apparently contrasting results regarding the relative importance of tropical upwelling versus horizontal transport for the seasonality of ozone above the tropical tropopause. Different analysis methods in the literature (Lagrangian versus Eulerian, and isentropic versus pressure vertical coordinates) yield different perspectives of ozone transport, and the results must be carefully compared in equivalent terms to avoid misinterpretation. By examining the Lagrangian calculations in the Eulerian formulation, we show here that the results are in fact consistent with each other and with a common understanding of the ozone transport processes near and above the tropical tropopause. We further emphasize that the complementary approaches are suited for answering two different scientific questions: (1) what drives the observed seasonal cycle in ozone at a particular level above the tropical tropopause? and (2) how important is horizontal transport from mid-latitudes for ozone concentrations in the tropical lower stratosphere? Regarding the first question, the analysis of the transformed Eulerian mean (TEM) ozone budget shows that the annual cycle in tropical upwelling is the main forcing of the ozone seasonality at altitudes with large vertical gradients in the tropical lower stratosphere. To answer the second question a Lagrangian framework must be used, and the results show that a large fraction (~50%) of the ozone molecules ascending through the tropical lower stratosphere is of extra-tropical origin and has been in-mixed from mid-latitudes.

  8. Ozone seasonality above the tropical tropopause: reconciling the Eulerian and Lagrangian perspectives of transport processes

    NASA Astrophysics Data System (ADS)

    Abalos, M.; Ploeger, F.; Konopka, P.; Randel, W. J.; Serrano, E.

    2013-07-01

    We aim to reconcile the recently published, apparently contrasting results regarding the relative importance of tropical upwelling versus horizontal transport for the seasonality of ozone above the tropical tropopause. Different analysis methods in the literature (Lagrangian versus Eulerian, and isentropic versus pressure vertical coordinates) yield different perspectives of ozone transport, and the results must be carefully compared in equivalent terms to avoid misinterpretation. By examining the Lagrangian calculations in the Eulerian formulation, we show here that the results are in fact consistent with each other and with a common understanding of the ozone transport processes near and above the tropical tropopause. We further emphasize that the complementary approaches are suited for answering two different scientific questions: (1) what drives the observed seasonal cycle in ozone at a particular level above the tropical tropopause? and (2) how important is horizontal transport from mid-latitudes for ozone concentrations in the tropical lower stratosphere? Regarding the first question, the analysis of the Transformed Eulerian Mean (TEM) ozone budget shows that the annual cycle in tropical upwelling is the main forcing of the ozone seasonality at altitudes with large vertical gradients in the tropical lower stratosphere. To answer the second question a Lagrangian framework must be used, and the results show that a large fraction (∼50%) of the ozone molecules ascending through the tropical lower stratosphere is of extra-tropical origin and has been in-mixed from mid-latitudes.

  9. Transport and reaction processes affecting the attenuation of landfill gas in cover soils.

    PubMed

    Molins, S; Mayer, K U; Scheutz, C; Kjeldsen, P

    2008-01-01

    Methane and trace organic gases produced in landfill waste are partly oxidized in the top 40 cm of landfill cover soils under aerobic conditions. The balance between the oxidation of landfill gases and the ingress of atmospheric oxygen into the soil cover determines the attenuation of emissions of methane, chlorofluorocarbons, and hydrochlorofluorocarbons to the atmosphere. This study was conducted to investigate the effect of oxidation reactions on the overall gas transport regime and to evaluate the contributions of various gas transport processes on methane attenuation in landfill cover soils. For this purpose, a reactive transport model that includes advection and the Dusty Gas Model for simulation of multicomponent gas diffusion was used. The simulations are constrained by data from a series of counter-gradient laboratory experiments. Diffusion typically accounts for over 99% of methane emission to the atmosphere. Oxygen supply into the soil column is driven exclusively by diffusion, whereas advection outward offsets part of the diffusive contribution. In the reaction zone, methane consumption reduces the pressure gradient, further decreasing the significance of advection near the top of the column. Simulations suggest that production of water or accumulation of exopolymeric substances due to microbially mediated methane oxidation can significantly reduce diffusive fluxes. Assuming a constant rate of methane production within a landfill, reduction of the diffusive transport properties, primarily due to exopolymeric substance production, may result in reduced methane attenuation due to limited O(2) -ingress. PMID:18268309

  10. A Coupling Kinetics Model for Pollutant Release and Transport in the Process of Landfill Settlement

    PubMed Central

    Zhao, Ying; Xue, Qiang; Liu, Lei

    2012-01-01

    A coupling kinetics model is developed to simulate the release and transport of landfill leachate pollutants in a deformable municipal solid waste landfill by taking into account of landfill settlement, seepage of leachate water, hydrolyse of insoluble and degradable organic pollutants in solid phase, biodegradation of soluble and degradable organic pollutants in solid phase and aqueous one, growth of aerobic and anaerobic microorganism, and consumption of dissolved oxygen. The release and transport of organic pollutants and microorganisms in landfills in the process of landfill settlement was simulated by considering no hydraulic effect. Simulation results demonstrated that the interaction between landfill settlement and the release, transport and biodegradation of landfill leachate pollutants was significant. Porosity and saturated hydraulic conductivity were not constants because of the landfill settlement, which affected the release, transport and biodegradation of landfill leachate pollutants, and furthermore acted on the landfill settlement. The simulation results accorded with the practical situation, which preliminarily verified the reliability of the mathematical model and the numerical program in this paper. PMID:23202755

  11. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers

    NASA Astrophysics Data System (ADS)

    You, Jingbi; Meng, Lei; Song, Tze-Bin; Guo, Tzung-Fang; Yang, Yang (Michael); Chang, Wei-Hsuan; Hong, Ziruo; Chen, Huajun; Zhou, Huanping; Chen, Qi; Liu, Yongsheng; De Marco, Nicholas; Yang, Yang

    2016-01-01

    Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiOx and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiOx/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%.

  12. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers.

    PubMed

    You, Jingbi; Meng, Lei; Song, Tze-Bin; Guo, Tzung-Fang; Yang, Yang Michael; Chang, Wei-Hsuan; Hong, Ziruo; Chen, Huajun; Zhou, Huanping; Chen, Qi; Liu, Yongsheng; De Marco, Nicholas; Yang, Yang

    2016-01-01

    Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiO(x) and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiO(x)/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%. PMID:26457966

  13. Amphetamine activates Rho GTPase signaling to mediate dopamine transporter internalization and acute behavioral effects of amphetamine.

    PubMed

    Wheeler, David S; Underhill, Suzanne M; Stolz, Donna B; Murdoch, Geoffrey H; Thiels, Edda; Romero, Guillermo; Amara, Susan G

    2015-12-22

    Acute amphetamine (AMPH) exposure elevates extracellular dopamine through a variety of mechanisms that include inhibition of dopamine reuptake, depletion of vesicular stores, and facilitation of dopamine efflux across the plasma membrane. Recent work has shown that the DAT substrate AMPH, unlike cocaine and other nontransported blockers, can also stimulate endocytosis of the plasma membrane dopamine transporter (DAT). Here, we show that when AMPH enters the cytoplasm it rapidly stimulates DAT internalization through a dynamin-dependent, clathrin-independent process. This effect, which can be observed in transfected cells, cultured dopamine neurons, and midbrain slices, is mediated by activation of the small GTPase RhoA. Inhibition of RhoA activity with C3 exotoxin or a dominant-negative RhoA blocks AMPH-induced DAT internalization. These actions depend on AMPH entry into the cell and are blocked by the DAT inhibitor cocaine. AMPH also stimulates cAMP accumulation and PKA-dependent inactivation of RhoA, thus providing a mechanism whereby PKA- and RhoA-dependent signaling pathways can interact to regulate the timing and robustness of AMPH's effects on DAT internalization. Consistent with this model, the activation of D1/D5 receptors that couple to PKA in dopamine neurons antagonizes RhoA activation, DAT internalization, and hyperlocomotion observed in mice after AMPH treatment. These observations support the existence of an unanticipated intracellular target that mediates the effects of AMPH on RhoA and cAMP signaling and suggest new pathways to target to disrupt AMPH action. PMID:26553986

  14. Gender differences in association between serotonin transporter gene polymorphism and resting-state EEG activity.

    PubMed

    Volf, N V; Belousova, L V; Knyazev, G G; Kulikov, A V

    2015-01-22

    Human brain oscillations represent important features of information processing and are highly heritable. Gender has been observed to affect association between the 5-HTTLPR (serotonin-transporter-linked polymorphic region) polymorphism and various endophenotypes. This study aimed to investigate the effects of 5-HTTLPR on the spontaneous electroencephalography (EEG) activity in healthy male and female subjects. DNA samples extracted from buccal swabs and resting EEG recorded at 60 standard leads were collected from 210 (101 men and 109 women) volunteers. Spectral EEG power estimates and cortical sources of EEG activity were investigated. It was shown that effects of 5-HTTLPR polymorphism on electrical activity of the brain vary as a function of gender. Women with the S/L genotype had greater global EEG power compared to men with the same genotype. In men, current source density was markedly different among genotype groups in only alpha 2 and alpha 3 frequency ranges: S/S allele carriers had higher current source density estimates in the left inferior parietal lobule in comparison with the L/L group. In women, genotype difference in global power asymmetry was found in the central-temporal region. Contrasting L/L and S/L genotype carriers also yielded significant effects in the right hemisphere inferior parietal lobule and the right postcentral gyrus with L/L genotype carriers showing lower current source density estimates than S/L genotype carriers in all but gamma bands. So, in women, the effects of 5-HTTLPR polymorphism were associated with modulation of the EEG activity in a wide range of EEG frequencies. The significance of the results lies in the demonstration of gene by sex interaction with resting EEG that has implications for understanding sex-related differences in affective states, emotion and cognition. PMID:25450956

  15. Amphetamine activates Rho GTPase signaling to mediate dopamine transporter internalization and acute behavioral effects of amphetamine

    PubMed Central

    Wheeler, David S.; Underhill, Suzanne M.; Stolz, Donna B.; Murdoch, Geoffrey H.; Thiels, Edda; Romero, Guillermo; Amara, Susan G.

    2015-01-01

    Acute amphetamine (AMPH) exposure elevates extracellular dopamine through a variety of mechanisms that include inhibition of dopamine reuptake, depletion of vesicular stores, and facilitation of dopamine efflux across the plasma membrane. Recent work has shown that the DAT substrate AMPH, unlike cocaine and other nontransported blockers, can also stimulate endocytosis of the plasma membrane dopamine transporter (DAT). Here, we show that when AMPH enters the cytoplasm it rapidly stimulates DAT internalization through a dynamin-dependent, clathrin-independent process. This effect, which can be observed in transfected cells, cultured dopamine neurons, and midbrain slices, is mediated by activation of the small GTPase RhoA. Inhibition of RhoA activity with C3 exotoxin or a dominant-negative RhoA blocks AMPH-induced DAT internalization. These actions depend on AMPH entry into the cell and are blocked by the DAT inhibitor cocaine. AMPH also stimulates cAMP accumulation and PKA-dependent inactivation of RhoA, thus providing a mechanism whereby PKA- and RhoA-dependent signaling pathways can interact to regulate the timing and robustness of AMPH’s effects on DAT internalization. Consistent with this model, the activation of D1/D5 receptors that couple to PKA in dopamine neurons antagonizes RhoA activation, DAT internalization, and hyperlocomotion observed in mice after AMPH treatment. These observations support the existence of an unanticipated intracellular target that mediates the effects of AMPH on RhoA and cAMP signaling and suggest new pathways to target to disrupt AMPH action. PMID:26553986

  16. Insulin Regulates the Activity of the High-Affinity Choline Transporter CHT.

    PubMed

    Fishwick, Katherine J; Rylett, R Jane

    2015-01-01

    Studies in humans and animal models show that neuronal insulin resistance increases the risk of developing Alzheimer's Disease (AD), and that insulin treatment may promote memory function. Cholinergic neurons play a critical role in cognitive and attentional processing and their dysfunction early in AD pathology may promote the progression of AD pathology. Synthesis and release of the neurotransmitter acetylcholine (ACh) is closely linked to the activity of the high-affinity choline transporter protein (CHT), but the impact of insulin receptor signaling and neuronal insulin resistance on these aspects of cholinergic function are unknown. In this study, we used differentiated SH-SY5Y cells stably-expressing CHT proteins to study the effect of insulin signaling on CHT activity and function. We find that choline uptake activity measured after acute addition of 20 nM insulin is significantly lower in cells that were grown for 24 h in media containing insulin compared to cells grown in the absence of insulin. This coincides with loss of ability to increase phospho-Protein Kinase B (PKB)/Akt levels in response to acute insulin stimulation in the chronic insulin-treated cells. Inhibition of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3-kinase) in cells significantly lowers phospho-PKB/Akt levels and decreases choline uptake activity. We show total internal reflection microscopy (TIRF) imaging of the dynamic movement of CHT proteins in live cells in response to depolarization and drug treatments. These data show that acute exposure of depolarized cells to insulin is coupled to transiently increased levels of CHT proteins at the cell surface, and that this is attenuated by chronic insulin exposure. Moreover, prolonged inhibition of PI3-kinase results in enhanced levels of CHT proteins at the cell surface by decreasing their rate of internalization. PMID:26161852

  17. Insulin Regulates the Activity of the High-Affinity Choline Transporter CHT

    PubMed Central

    Fishwick, Katherine J.; Rylett, R. Jane

    2015-01-01

    Studies in humans and animal models show that neuronal insulin resistance increases the risk of developing Alzheimer’s Disease (AD), and that insulin treatment may promote memory function. Cholinergic neurons play a critical role in cognitive and attentional processing and their dysfunction early in AD pathology may promote the progression of AD pathology. Synthesis and release of the neurotransmitter acetylcholine (ACh) is closely linked to the activity of the high-affinity choline transporter protein (CHT), but the impact of insulin receptor signaling and neuronal insulin resistance on these aspects of cholinergic function are unknown. In this study, we used differentiated SH-SY5Y cells stably-expressing CHT proteins to study the effect of insulin signaling on CHT activity and function. We find that choline uptake activity measured after acute addition of 20 nM insulin is significantly lower in cells that were grown for 24 h in media containing insulin compared to cells grown in the absence of insulin. This coincides with loss of ability to increase phospho-Protein Kinase B (PKB)/Akt levels in response to acute insulin stimulation in the chronic insulin-treated cells. Inhibition of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3-kinase) in cells significantly lowers phospho-PKB/Akt levels and decreases choline uptake activity. We show total internal reflection microscopy (TIRF) imaging of the dynamic movement of CHT proteins in live cells in response to depolarization and drug treatments. These data show that acute exposure of depolarized cells to insulin is coupled to transiently increased levels of CHT proteins at the cell surface, and that this is attenuated by chronic insulin exposure. Moreover, prolonged inhibition of PI3-kinase results in enhanced levels of CHT proteins at the cell surface by decreasing their rate of internalization. PMID:26161852

  18. [Relationships between H2O2 metabolism and Ca2+ transport in dormancy-breaking process of nectarine floral buds].

    PubMed

    Tan, Yue; Gao, Dong-sheng; Li, Ling; Wei, Hai-rong; Wang, Jia-wei; Liu, Qing-zhong

    2015-02-01

    In order to explore regulatory function of H2O2 in bud dormancy release, main effects of three dormancy-breaking treatments (high temperature, hydrogen cyanamide and TDZ) on H2O2 metabolism were determined, and impacts of H2O2 on Ca2+ transport were tested using non-invasive micro-test technique. The results showed that both high temperature and hydrogen cyanamide induced H2O2 accumulation and CAT inhibition were efficient in breaking dormancy during deep dormancy period. However, TDZ showed little impacts on H2O2 metabolism and was much less effective in breaking dormancy. Dormant floral primordium was absorbing state to exogenous Ca2+ due to active calcium channels. The Ca2+ transport could be changed by exogenous H2O2. H2O2 of low concentration reduced the absorption rate of Ca2+, and at high concentration, it changed the Ca2+ transport direction from absorption to release. The results indicated that H2O2 signals were related with Ca2+ signals in dormant buds. Ca2+ signal regulated by H2O2 accumulation might be important in the dormancy-breaking signal transduction process induced by high temperature and hydrogen cyanamide. PMID:26094456

  19. Revealing the flux: Using processed Husimi maps to visualize dynamics of bound systems and mesoscopic transport

    NASA Astrophysics Data System (ADS)

    Mason, Douglas J.; Borunda, Mario F.; Heller, Eric J.

    2015-04-01

    We elaborate upon the "processed Husimi map" representation for visualizing quantum wave functions using coherent states as a measurement of the local phase space to produce a vector field related to the probability flux. Adapted from the Husimi projection, the processed Husimi map is mathematically related to the flux operator under certain limits but offers a robust and flexible alternative since it can operate away from these limits and in systems that exhibit zero flux. The processed Husimi map is further capable of revealing the full classical dynamics underlying a quantum wave function since it reverse engineers the wave function to yield the underlying classical ray structure. We demonstrate the capabilities of processed Husimi maps on bound systems with and without electromagnetic fields, as well as on open systems on and off resonance, to examine the relationship between closed system eigenstates and mesoscopic transport.

  20. Assessment of Controlling Processes for Field-Scale Uranium Reactive Transport under Highly Transient Flow Conditions

    SciTech Connect

    Ma, Rui; Zheng, Chunmiao; Liu, Chongxuan; Greskowiak, Janek; Prommer, Henning; Zachara, John M.

    2014-02-06

    This paper presents the results of a comprehensive model-based analysis of a uranium tracer test conducted at the U.S Department of Energy Hanford 300 Area (300A) IFRC site. A three-dimensional multi-component reactive transport model was employed to assess the key factors and processes that control the field-scale uranium reactive transport. Taking into consideration of relevant physical and chemical processes, the selected conceptual/numerical model replicates the spatial and temporal variations of the observed U(VI) concentrations reasonably well in spite of the highly complex field conditions. A sensitivity analysis was performed to interrogate the relative importance of various processes and factors for reactive transport of U(VI) at the field-scale. The results indicate that multi-rate U(VI) sorption/desorption, U(VI) surface complexation reactions, and initial U(VI) concentrations were the most important processes and factors controlling U(VI) migration. On the other hand, cation exchange reactions, the choice of the surface complexation model, and dual-domain mass transfer processes, which were previously identified to be important in laboratory experiments, played less important roles under the field-scale experimental condition at the 300A site. However, the model simulations also revealed that the groundwater chemistry was relatively stable during the uranium tracer experiment and therefore presumably not dynamic enough to appropriately assess the effects of ion exchange reaction and the choice of surface complexation models on U(VI) sorption and desorption. Furthermore, it also showed that the field experimental duration (16 days) was not sufficiently long to precisely assess the role of a majority of the sorption sites that were accessed by slow kinetic processes within the dual domain model. The sensitivity analysis revealed the crucial role of the intraborehole flow that occurred within the long-screened monitoring wells and thus significantly