WorldWideScience

Sample records for main transport mechanism

  1. Filtration as the main transport mechanism of protein exchange between plasma and the peritoneal cavity in hepatic cirrhosis

    DEFF Research Database (Denmark)

    Henriksen, J H; Lassen, N A; Parving, H H; Winkler, K

    1980-01-01

    plasma protein flux averaged 0.4% of the intravascular protein mass per hour. The results point to filtration (convective flux) as the main transport mechanism responsible for protein passage into the peritoneal cavity as well as for the protein passage (lymphatic drainage) back into the plasma. Pressure...

  2. Main transport challenges in South Eastern Europe, after enlargement

    OpenAIRE

    Giannopoulos, G. A.

    2005-01-01

    This paper looks at the main challenges that are facing the Transport sector in the countries of S. E. Europe after enlargement. First, it looks at the challenge of setting a common Transport policy and points as priority areas the questions of: frontier crossings, road transport quotas, working hours (road transport), restructuring of railways, promotion of Rail Freight Freeways, new financing schemes through Public Private Partnerships, and other issues. Then it looks at the factors that ...

  3. Tape transport mechanism

    International Nuclear Information System (INIS)

    A device is provided for transporting, in a stepwise manner, tape between a feed reel and takeup reel. An indexer moves across the normal path of the tape displacing it while the tape on the takeup reel side of the indexer is braked. After displacement, the takeup reel takes up the displaced tape while the tape on the feed reel side of the indexer is braked, providing stepwise tape transport in precise intervals determined by the amount of displacement caused by the indexer

  4. Turbulent transport and lithium destruction in main sequence stars

    International Nuclear Information System (INIS)

    The depletion of lithium in giants seems to result from the destruction of lithium on the main sequence prior to the formation of the giants. Lithium is carried by turbulent diffusion towards the region where it is burned. The measurement of the abundance of lithium in giants gives then the possibility of determining the rate of transport. It explains the depletion of lithium on the main sequence, the depletion of lithium in the Sun, is compatible with the loss of angular momentum of the Sun and suggests an explanation of the (V sin i) distribution function for main sequence stars, and for giant stars. (orig./BJ)

  5. Truck and Transport Mechanic. Occupational Analyses Series.

    Science.gov (United States)

    McRory, Aline; Ally, Mohamed

    This analysis covers tasks performed by a truck and transport mechanic, an occupational title some provinces and territories of Canada have also identified as commercial transport vehicle mechanic; transport truck mechanic; truck and coach technician; and truck and transport service technician. A guide to analysis discusses development, structure,

  6. Summary on main policies, funding mechanisms, actors and trends

    DEFF Research Database (Denmark)

    Kressler, Florian; Weiss, Lucas; Åkerman, Jonas; Gudmundsson, Henrik; Guihéry, Laurent; Vesela, Jirina

    This document summarizes the output of WP 3 on policies, funding mechanisms, actors and trends relating the four thematic groups. Each thematic group examines one goal of the White Paper on Transport, published by the European Commission in 2011. The purpose of this document is to provide input f...

  7. Membranes, mechanics, and intracellular transport

    Science.gov (United States)

    Parthasarathy, Raghuveer

    2012-10-01

    Cellular membranes are remarkable materials -- self-assembled, flexible, two-dimensional fluids. Understanding how proteins manipulate membrane curvature is crucial to understanding the transport of cargo in cells, yet the mechanical activities of trafficking proteins remain poorly understood. Using an optical-trap based assay involving dynamic deformation of biomimetic membranes, we have examined the behavior of Sar1, a key component of the COPII family of transport proteins. We find that Sar1 from yeast (S. cerevisiae) lowers membrane rigidity by up to 100% as a function of its concentration, thereby lowering the energetic cost of membrane deformation. Human Sar1 proteins can also lower the mechanical rigidity of the membranes to which they bind. However, unlike the yeast proteins, the rigidity is not a monotonically decreasing function of concentration but rather shows increased rigidity and decreased mobility at high concentrations that implies interactions between proteins. In addition to describing this study of membrane mechanics, I'll also discuss some topics relevant to a range of biophysical investigations, such as the insights provided by imaging methods and open questions in the dynamics of multicellular systems.

  8. Summary on main policies, funding mechanisms, actors and trends

    OpenAIRE

    Kressler, Florian; Weiss, Lucas; Åkerman, Jonas; Gudmundsson, Henrik; Guihéry, Laurent; Vesela, Jirina

    2014-01-01

    This document summarizes the output of WP 3 on policies, funding mechanisms, actors and trends relating the four thematic groups. Each thematic group examines one goal of the White Paper on Transport, published by the European Commission in 2011. The purpose of this document is to provide input for further work carried out in the project, especially the road-mapping exercises and the strategic outlook carried out in WP 6. The inputs for this document include information from a literature revi...

  9. Mechanisms of transport in radiative improved mode

    Energy Technology Data Exchange (ETDEWEB)

    Tokar, M.Z. [EURATOM-FZJ, Institut fur Plasmaphysik, Julich (Germany); Dumortier, P. [Association ' EURATOM-Belgian State' , ERM-KMS, Brussels (Belgium); Jackson, G.L. [DIII-D National Fusion Facility, San Diego, CA (US)] [and others

    2003-07-01

    Improvement of confinement by a deliberate seeding of impurities line neon and argon has been found in many devices. Most intensively this phenomenon was studied in the limiter tokamak TEXTOR, where it was called radiative improved (RI) mode, and in the divertor machine DII-D. Recent experiments on TFTR, JT-60 and JET have demonstrated that by an optimization of seeding procedure a positive effect of impurities can be achieved in reactor scale devices. Extensive theoretical and modelling activities were performed during past years in order to understand the mechanisms of confinement improvement in RI-mode. Characteristics of drift instabilities namely the ion temperature gradient (ITG) and dissipate trapped electron (DTE) modes, which provide the main contribution to the anomalous transport in tokamaks, have been analyzed by the code for Gyro-Kinetic Stability. The behavior of non-linear turbulent eddies and vortices was studied in 'particle in cell' simulations. Fluid approximation has been applied to asses the effect of impurities on anomalous transport. All these studies predict a reduction of turbulence originated from the most dangerous ITG modes. Computations by a transport code with models for anomalous transport coefficients due to drift micro-instabilities reproduce many peculiarities of RI-plasmas. (author)

  10. Mechanisms of transport in radiative improved mode

    International Nuclear Information System (INIS)

    Improvement of confinement by a deliberate seeding of impurities line neon and argon has been found in many devices. Most intensively this phenomenon was studied in the limiter tokamak TEXTOR, where it was called radiative improved (RI) mode, and in the divertor machine DII-D. Recent experiments on TFTR, JT-60 and JET have demonstrated that by an optimization of seeding procedure a positive effect of impurities can be achieved in reactor scale devices. Extensive theoretical and modelling activities were performed during past years in order to understand the mechanisms of confinement improvement in RI-mode. Characteristics of drift instabilities namely the ion temperature gradient (ITG) and dissipate trapped electron (DTE) modes, which provide the main contribution to the anomalous transport in tokamaks, have been analyzed by the code for Gyro-Kinetic Stability. The behavior of non-linear turbulent eddies and vortices was studied in 'particle in cell' simulations. Fluid approximation has been applied to asses the effect of impurities on anomalous transport. All these studies predict a reduction of turbulence originated from the most dangerous ITG modes. Computations by a transport code with models for anomalous transport coefficients due to drift micro-instabilities reproduce many peculiarities of RI-plasmas. (author)

  11. Main academic institutions conducting research in the public transport area

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, B.E. [Lund Inst. of Tech. (Sweden). Dept. of Traffic Planning and Engineering

    1997-12-01

    The international exchange of knowledge is becoming increasingly important for all activities. Within Europe, the need for simple reviews of institutions within one and the same subject area has become more tangible since the European Union started its public transport research program. The survey has been carried out in two stages. First a questionnaire was sent to those institutions, public transport authorities, public transport associations and individuals within the subject area that were known to the Department. In this questionnaire we asked for the names and addresses of institutions at colleges and universities where significant research on public transport is carried out. In a second stage, a list was compiled of the 48 institutions that were named in the results of the first questionnaire. This list was sent to these institutions with the request for a brief presentation of their research within the public transport sector and information on any institution they felt were missing in the list. We found further interesting institutions on the Internet. The final list contains more than 60 institutions outside the Nordic area. Within the Nordic countries we have exclusively followed our own address list of institutions with long-term research work within the subject area

  12. Main Directions and Mechanisms of Industrial Policy of Russia

    Directory of Open Access Journals (Sweden)

    Irina M. Podmolodina

    2015-06-01

    Full Text Available Under difficult economic conditions for Russian business, characterized by difficulties of Russian companies’ access to foreign modern technologies and long-term financial resources, there is a need for elaborated industrial policy which facilitates the development of national industry and provision of economic security of the country. With current sanctions, the Russian enterprises faced the problems of impossibility of getting foreign equipment under the previously signed contracts, re-orientation of orders for the similar domestic production, and attraction of financial resources from internal sources. Solution to these problems lies in the plane of development of “new” industrial policy. The purpose of the article is to determine main directions and mechanisms for realization of measures of industrial policy which facilitates the development of domestic industrial production, implementation of achievements of scientific and technological progress into industrial processes, and import substitution of science intensive products. Realization of industrial policy of Russia supposes the formation of special conditions. These are favorable economic and socio-infrastructural conditions, attractive entrepreneurial regime, high level of training of personnel for various industries, and informational support of government structures. Activation of innovational activity requires mechanisms that ensure the improvement of conditions for fair competition and increase of motivation of companies for innovations; regulation of product markets (service markets and sectorial regulation for distribution of leading technologies; development of the system of technical regulation, which includes harmonization of legislative basis of Russia and the EU countries in this sphere; simplification of a procedure of entry of new products into the market; simplification and quickening of the procedures of certification, including as to the international quality standards; simplification of a mechanism of import of technologies; strengthening of requirements to efficiency of enterprises’ usage of natural resources, safety of products (services for ecology and health of population, decrease of energy and materials consumption; development of the system of appropriate bonuses and sanctions, harmonization of Russian standards with international ones, particularly, in the directions that are characterized by perspectives of expansion for export of innovational products.

  13. Angular momentum transport efficiency in post-main sequence low-mass stars

    Science.gov (United States)

    Spada, F.; Gellert, M.; Arlt, R.; Deheuvels, S.

    2016-04-01

    Context. Using asteroseismic techniques, it has recently become possible to probe the internal rotation profile of low-mass (≈1.1-1.5 M⊙) subgiant and red giant stars. Under the assumption of local angular momentum conservation, the core contraction and envelope expansion occurring at the end of the main sequence would result in a much larger internal differential rotation than observed. This suggests that angular momentum redistribution must be taking place in the interior of these stars. Aims: We investigate the physical nature of the angular momentum redistribution mechanisms operating in stellar interiors by constraining the efficiency of post-main sequence rotational coupling. Methods: We model the rotational evolution of a 1.25M⊙ star using the Yale Rotational stellar Evolution Code. Our models take into account the magnetic wind braking occurring at the surface of the star and the angular momentum transport in the interior, with an efficiency dependent on the degree of internal differential rotation. Results: We find that models including a dependence of the angular momentum transport efficiency on the radial rotational shear reproduce very well the observations. The best fit of the data is obtained with an angular momentum transport coefficient scaling with the ratio of the rotation rate of the radiative interior over that of the convective envelope of the star as a power law of exponent ≈3. This scaling is consistent with the predictions of recent numerical simulations of the Azimuthal Magneto-Rotational Instability. Conclusions: We show that an angular momentum transport process whose efficiency varies during the stellar evolution through a dependence on the level of internal differential rotation is required to explain the observed post-main sequence rotational evolution of low-mass stars.

  14. Angular momentum transport efficiency in post-main sequence low-mass stars

    CERN Document Server

    Spada, F; Arlt, R; Deheuvels, S

    2016-01-01

    Context. Using asteroseismic techniques, it has recently become possible to probe the internal rotation profile of low-mass (~1.1-1.5 Msun) subgiant and red giant stars. Under the assumption of local angular momentum conservation, the core contraction and envelope expansion occurring at the end of the main sequence would result in a much larger internal differential rotation than observed. This suggests that angular momentum redistribution must be taking place in the interior of these stars. Aims. We investigate the physical nature of the angular momentum redistribution mechanisms operating in stellar interiors by constraining the efficiency of post-main sequence rotational coupling. Methods. We model the rotational evolution of a 1.25 Msun star using the Yale Rotational stellar Evolution Code. Our models take into account the magnetic wind braking occurring at the surface of the star and the angular momentum transport in the interior, with an efficiency dependent on the degree of internal differential rotati...

  15. Application of mechanized material transport in uranium mine

    International Nuclear Information System (INIS)

    Mechanisms had to be developed for speeding up the transport of material to the underground while increasing work safety and hygiene, this in view of the continuously growing volume of uranium ore mining in the pit. Attention was concentrated mainly on problems of transporting long material through the pit to the mining face. Three types of mechanisms were developed: a suspended material cage which is used to transport material with a length of up to 4 m, a suspension element for the transport of long flanged tubes and a suspension element for the transport of rails. The previous method of material handling is characterized and the new method using the suspended cage is described in detail. The actual amount of material transported in one year is given as is the time needed for manual transport and for transport using the cage. Annual savings are calculated. The transport of tubes and rails using the two suspension elements is described and 14 photographs are published showing the developed mechanisms and their uses. (A.K.)

  16. Seesaw mechanism in turbulence and turbulent transport

    International Nuclear Information System (INIS)

    Full text: Theory of nonlocal transport has been developed, based upon the statistical theory of plasma turbulence. Essence is that fluctuations (with long radial correlation length) can be excited by nonlinear processes, although they are linearly stable. Experiments have reported the non-diffusive mechanisms in rapid response of transport between distant radii. Simulations have demonstrated that transport barrier can be established while increasing linear growth rate of local instabilities. These await application of theory of nonlocal transport. Example of such nonlinearly-driven, meso-scale fluctuations is the zonal flow (ZF). ZFs grow extracting energy from microscopic fluctuations so as to reduce the turbulence and turbulent transport. Because the radial correlation length of ZF is longer than those for microscopic fluctuations, which are inducing turbulent transport, ZF, which is driven fluctuations at one radius, can suppress fluctuations at distant radii. Thus, the fluctuations exchange energy over the distance that is much longer than autocorrelation length of microscopic fluctuations. This mechanism induces new nonlocal interactions in turbulent transport. That is, strong fluctuations at particular radius can suppress fluctuations at different radius, via induction of ZFs. Stronger fluctuations suppress weaker fluctuations. This is called the seesaw mechanism via ZFs. Owing to this mechanism, the turbulence transport is not determined by local parameters alone, but by parameters at far distance. The transient response is much faster than the process governed by diffusive processes. [This work is partly supported by the Grant-in-Aid for Specially-Promoted Research (16002005), the Grant-in-Aid for Scientific Research (19360418) and collaboration programme of NIFS.] (author)

  17. Edge transport and its interconnection with main chamber recycling in ASDEX upgrade

    International Nuclear Information System (INIS)

    Edge profiles of electron temperature and density are measured in ASDEX Upgrade with high spatial resolution of 2-3 mm with Thomson scattering. In the region of the edge transport barrier in ELMy H-mode, the gradient lengths of Te and ne are found closely coupled, with the temperature profile twice as steep as the density profile corresponding to ηe ∼ 2. The edge density in the region of the barrier foot is closely coupled to the main chamber recycling, with no strong dependence on other parameters. In contrast the density rise from the outer barrier foot to the pedestal exhibits pronounced dependence on plasma current and shaping, indicating quite different mechanisms determining the absolute density and its gradient. (author)

  18. Edge transport and its interconnection with main chamber recycling in ASDEX Upgrade

    International Nuclear Information System (INIS)

    Edge profiles of electron temperature and density are measured in ASDEX Upgrade with a high spatial resolution of 2-3 mm with Thomson scattering. In the region of the edge transport barrier in ELMy H-mode, the gradient lengths of Te and ne are found closely coupled, with the temperature decay length two times shorter than the density decay length corresponding to ηe ∼ 2. The ηe constraint allows us to calculate the electron temperature and density profiles from the pressure profile if the density and temperature values are known at one spatial position. The edge density in the region of the barrier foot is closely coupled to the main chamber recycling, with no strong dependence on other parameters. In contrast, the density rise from the outer barrier foot to the pedestal exhibits pronounced dependence on plasma current and shaping, indicating quite different mechanisms determining the absolute density and its gradient. (author)

  19. Invasive home mechanical ventilation, mainly focused on neuromuscular disorders

    Directory of Open Access Journals (Sweden)

    Börger, Sandra

    2010-01-01

    Full Text Available Introduction and background: Invasive home mechanical ventilation is used for patients with chronic respiratory insufficiency. This elaborate and technology-dependent ventilation is carried out via an artificial airway (tracheal cannula to the trachea. Exact numbers about the incidence of home mechanical ventilation are not available. Patients with neuromuscular diseases represent a large portion of it. Research questions: Specific research questions are formulated and answered concerning the dimensions of medicine/nursing, economics, social, ethical and legal aspects. Beyond the technical aspect of the invasive home, mechanical ventilation, medical questions also deal with the patient’s symptoms and clinical signs as well as the frequency of complications. Economic questions pertain to the composition of costs and the differences to other ways of homecare concerning costs and quality of care. Questions regarding social aspects consider the health-related quality of life of patients and caregivers. Additionally, the ethical aspects connected to the decision of home mechanical ventilation are viewed. Finally, legal aspects of financing invasive home mechanical ventilation are discussed. Methods: Based on a systematic literature search in 2008 in a total of 31 relevant databases current literature is viewed and selected by means of fixed criteria. Randomized controlled studies, systematic reviews and HTA reports (health technology assessment, clinical studies with patient numbers above ten, health-economic evaluations, primary studies with particular cost analyses and quality-of-life studies related to the research questions are included in the analysis. Results and discussion: Invasive mechanical ventilation may improve symptoms of hypoventilation, as the analysis of the literature shows. An increase in life expectancy is likely, but for ethical reasons it is not confirmed by premium-quality studies. Complications (e. g. pneumonia are rare. Mobile home ventilators are available for the implementation of the ventilation. Their technical performance however, differs regrettably. Studies comparing the economic aspects of ventilation in a hospital to outpatient ventilation, describe home ventilation as a more cost-effective alternative to in-patient care in an intensive care unit, however, more expensive in comparison to a noninvasive (via mask ventilation. Higher expenses arise due to the necessary equipment and the high expenditure of time for the partial 24-hour care of the affected patients through highly qualified personnel. However, none of the studies applies to the German provisionary conditions. The calculated costs strongly depend on national medical fees and wages of caregivers, which barely allows a transmission of the results. The results of quality-of-life studies are mostly qualitative. The patient’s quality of life using mechanical ventilation is predominantly considered well. Caregivers of ventilated patients report positive as well as negative ratings. Regarding the ethical questions, it was researched which aspects of ventilation implementation will have to be considered. From a legal point of view the financing of home ventilation, especially invasive mechanical ventilation, requiring specialised technical nursing is regulated in the code of social law (Sozialgesetzbuch V. The absorption of costs is distributed to different insurance carriers, who often, due to cost pressures within the health care system, insurance carriers, who consider others and not themselves as responsible. Therefore in practice, the necessity to enforce a claim of cost absorption often arises in order to exercise the basic right of free choice of location. Conclusion: Positive effects of the invasive mechanical ventilation (overall survival and symptomatic are highly probable based on the analysed literature, although with a low level of evidence. An establishment of a home ventilation registry and health care research to ascertain valid data to improve outpatient structures is necessary. Gathering specific German data is needed to adequately depict the national concepts of provision and reimbursement. A differentiation of the cost structure according to the type of chosen outpatient care is currently not possible. There is no existing literature concerning the difference of life quality depending on the chosen outpatient care (homecare, assisted living, or in a nursing home specialised in invasive home ventilation. Further research is required. For a so called participative decision – made by the patient after intense counselling – an early and honest patient education pro respectively contra invasive mechanical ventilation is needed. Besides the long term survival, the quality of life and individual, social and religious aspects have also to be considered.

  20. Peroxisomal ABC transporters: functions and mechanism.

    Science.gov (United States)

    Baker, Alison; Carrier, David J; Schaedler, Theresia; Waterham, Hans R; van Roermund, Carlo W; Theodoulou, Frederica L

    2015-10-01

    Peroxisomes are arguably the most biochemically versatile of all eukaryotic organelles. Their metabolic functions vary between different organisms, between different tissue typesof the same organism and even between different developmental stages or in response to changed environmental conditions. New functions for peroxisomes are still being discovered and their importance is underscored by the severe phenotypes that can arise as a result of peroxisome dysfunction. The ?-oxidation pathway is central to peroxisomal metabolism, but the substrates processed are very diverse, reflecting the diversity of peroxisomes across species. Substrates for ?-oxidation enter peroxisomes via ATP-binding cassette (ABC) transporters of subfamily D; (ABCD) and are activated by specific acyl CoA synthetases for further metabolism. Humans have three peroxisomal ABCD family members, which are half transporters that homodimerize and have distinct but partially overlapping substrate specificity; Saccharomyces cerevisiae has two half transporters that heterodimerize and plants have a single peroxisomal ABC transporter that is a fused heterodimer and which appears to be the single entry point into peroxisomes for a very wide variety of ?-oxidation substrates. Our studies suggest that the Arabidopsis peroxisomal ABC transporter AtABCD1 accepts acyl CoA substrates, cleaves them before or during transport followed by reactivation by peroxisomal synthetases. We propose that this is a general mechanism to provide specificity to this class of transporters and by which amphipathic compounds are moved across peroxisome membranes. PMID:26517910

  1. Molecular mechanism of biological proton transport

    International Nuclear Information System (INIS)

    Proton transport across lipid membranes is a fundamental aspect of biological energy transduction (metabolism). This function is believed to be mediated by a Grotthuss mechanism involving proton hopping along hydrogen-bonded networks embedded in membrane-spanning proteins. Using molecular simulations, we have explored the structural, dynamic, and thermodynamic properties giving rise to long-range proton translocation in hydrogen-bonded networks involving water molecules, or 'water wires,' which are emerging as ubiquitous H+-transport devices in biological systems. (c) 1999 American Institute of Physics

  2. Dynamic analysis of the mechanical systems vibrating transversally in transportation

    Directory of Open Access Journals (Sweden)

    A. Buchacz

    2007-01-01

    Full Text Available Purpose: Purpose of this paper is analysis and modelling of mechanical systems in transportation. Thecontemporary technical problems are lashed with high work demands such as high speeds of mechanisms, usinglower density materials, high precision of work, etc. The main objective of this thesis was the dynamical analysiswith taking into consideration the interaction between main motion and local vibrations during the model isloaded by transverse forces.Design/methodology/approach: Equations of motion were derived by classical methods, the Lagrangeequations with generalized coordinates and generalized velocities assumed as orthogonal projections ofindividual coordinates and velocities of the beam and manipulators to axes of the global inertial frame.Findings: Presented mathematical model of the transversally vibrating systems in planar transportation can beput to use to derivation of the dynamical flexibility of these systems, moreover those equations are the startingpoint to the analysis of complex systems. In particular we can use those equations to derivation of the substitutedynamical flexibility of multibody systems.Research limitations/implications: There were considered mechanical systems vibrating transversally in termsof plane motion. Next problem of dynamical analysis is the analysis of systems in non-planar transportation andsystems loaded by longitudinal forces.Practical implications: Results of this thesis can be put to use into all machines and mechanisms running intransportation such as wind power plants, high speed turbines, rotors, manipulators and in aerodynamics issues,etc. Some results ought to be modified and adopted to appropriate models.Originality/value: High requirements applying to parameters of work of machines and mechanisms are causedthe new research and new ways of modelling and analyzing those systems. One of these ways are presented inthis thesis. There was defined the transportation effect for models vibrating transversally.

  3. Mechanical systems vibrating longitudinally with the transportation effect

    Directory of Open Access Journals (Sweden)

    S. Żółkiewski

    2007-03-01

    Full Text Available Purpose: High work speeds of mechanisms, using materials with high flexibility, high precision of work, etc. are the cause of searching of the new ways of modelling. One of these ways is presented in this thesis. The main purpose of this thesis is the dynamical analysis with taking into consideration the interaction between main motion and local vibrations during the model is loaded by longitudinal forces.Design/methodology/approach: Derived equations of motion were made by classical methods, with generalized coordinates and generalized velocities assumed as orthogonal projections of individual coordinates and velocities of the rod and manipulators to axes of the global inertial frame.Findings: Mathematical model of the longitudinally vibrating systems in terms of plane motion can be put to use to derivation of the dynamical flexibility of these systems, and also those equations are the starting point to the analysis of complex systems, especially we can use those equations to derivation of the substitute dynamical flexibility of n-linked systems in transportation.Research limitations/implications: In the thesis were considered mechanical systems vibrating longitudinally in terms of rotation. Next problem of dynamical analysis is the analysis of systems in non-planar transportation and systems loaded by transversal forces.Practical implications: Results of this thesis can be put to use into machines and mechanisms in transportation such as: wind power plant, high speed turbines, rotors, manipulators and in aerodynamics issues, etc.Originality/value: Up to now there were analyzed beams and rods in a separate way, first main motion of the system and after that the local vibrations. The new approach of modelling were presented by authors of this thesis, a new modelling took into consideration the interaction between those two displacement. There was defined the transportation effect for models vibrating longitudinally in this thesis.

  4. Evaporation as the transport mechanism of metals in arid regions

    KAUST Repository

    Lima, Ana T.

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust. © 2014 Elsevier Ltd.

  5. As if Kyoto mattered: The clean development mechanism and transportation

    International Nuclear Information System (INIS)

    Transportation is a major source of greenhouse gas (GHG) emissions and the most rapidly growing anthropogenic source. In the future, the developing world will account for the largest share of transport GHG increases. Four basic components drive transportation energy consumption and GHG emissions: activities (A), mode share (S), fuel intensity (I) and fuel choice (F) (ASIF). Currently, the Kyoto Protocol's clean development mechanism (CDM) serves as the main international market-based tool designed to reduce GHG emissions from the developing world. Theoretically, the CDM has the dual purpose of helping developing countries achieve 'sustainable development' goals and industrialized countries meet their Kyoto emissions reduction commitments. This paper reviews overall CDM activities and transportation CDM activities to date and then presents findings from three case studies of transportation CDM possibilities examined with the ASIF framework in Santiago de Chile. The analysis suggests that bus technology switch (I) provides a fairly good project fit for the CDM, while options aimed at inducing mode share (S) to bicycle, or modifying travel demand via land use changes (ASI) face considerable challenges. The implications of the findings for the CDM and the 'post-Kyoto' world are discussed

  6. Studies on lipid transport mechanism in the fish

    International Nuclear Information System (INIS)

    In mammals, absorbed micelles are resynthesized in the epithelial cells of the intestine and transported as chylomicrons through the lymphatic route, then as various lipoproteins in the circulatory system. It is rather difficult to draw conclusions about the dynamic processes involved in the absorption and transport of lipids, since there are few studies on these processes in fish. From the cannulated tube of a carp, 0.8 ml of blood was collected at various intervals after feeding. The disc electrophoresis pattern of carp blood plasma shows three main lipoprotein bands when prestained with acetylated Suden black B: Band 1 (albumin lipid complex), Band 2 (near alpha2-lipoprotein) and Band 3 (near beta- and pre-beta-lipoproteins of human plasma). Incorporation of palmitic acid into plasma lipid classes in starved fish was markedly characterized by the initial appearance within 1/2-3 hr of FFA associated mainly with Band 1 followed by gradual increase in TG and PL later. Under normal conditions, high levels of FFA appeared; however, TG associated with Band 3 and 1 appeared distinctly only after 6-12 hr. In the case of tripalmitin feeding, FFA appeared first, the incorporation being moderate but constant, followed by TG (after 3 hr) as the major lipid constituent associated first with Band 3 which seemed to be converted to Band 1 after 6 hr. It can be pointed out from these results that the mammalian lipid transport mechanism is not applicable to fish; instead, Band 1 associated mainly with FFA plays an important role in fish lipid transport. (auth.)

  7. Chemical and mechanical control of corrosion product transport

    Energy Technology Data Exchange (ETDEWEB)

    Hede Larsen, O.; Blum, R. [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark); Daucik, K. [I/S Skaerbaekvaerket, Faelleskemikerne, Fredericia (Denmark)

    1996-12-01

    The corrosion products formed in the condensate and feedwater system of once-through boilers are precipitated and deposited inside the evaporator tubes mainly in the burner zone at the highest heat flux. Depositions lead to increased oxidation rate and increased metal temperature of the evaporator tubes, hereby decreasing tube lifetime. This effect is more important in the new high efficiency USC boilers due to increased feedwater temperature and hence higher thermal load on the evaporator tubes. The only way to reduce the load on the evaporator tubes is to minimise corrosion product transport to the boiler. Two general methods for minimising corrosion product transport to the boiler have been evaluated through measurement campaigns for Fe in the water/steam cycle in supercritical boilers within the ELSAM area. One method is to reduce corrosion in the low temperature condensate system by changing conditioning mode from alkaline volatile treatment (AVT) to oxygenated treatment (OT). The other method is to filtrate part of the condensate with a mechanical filter at the deaerator. The results show, that both methods are effective at minimising Fe-transport to the boiler, but changing to OT has the highest effect and should always be used, whenever high purity condensate is maintained. Whether mechanical filtration also is required, depends on the boiler, specifically the load on the evaporator. A simplified calculation model for lifetime evaluation of evaporator tubes has been developed. This model has been used for evaluating the effect of corrosion product transport to the boiler on evaporator tube lifetime. Conventional supercritical boilers generally can achieve sufficient lifetime by AVT and even better by OT, whereas all measures to reduce Fe-content of feedwater, including OT and mechanical filtration, should be taken, to ensure sufficient lifetime for the new boilers with advanced steam data - 290 bar/580 deg. C and above. (au)

  8. Role of different scattering mechanisms on the temperature dependence of transport in graphene

    Science.gov (United States)

    Sarkar, Suman; Amin, Kazi Rafsanjani; Modak, Ranjan; Singh, Amandeep; Mukerjee, Subroto; Bid, Aveek

    2015-01-01

    Detailed experimental and theoretical studies of the temperature dependence of the effect of different scattering mechanisms on electrical transport properties of graphene devices are presented. We find that for high mobility devices the transport properties are mainly governed by completely screened short range impurity scattering. On the other hand, for the low mobility devices transport properties are determined by both types of scattering potentials - long range due to ionized impurities and short range due to completely screened charged impurities. The results could be explained in the framework of Boltzmann transport equations involving the two independent scattering mechanisms. PMID:26608479

  9. Osmoregulation in zebrafish: ion transport mechanisms and functional regulation.

    Science.gov (United States)

    Guh, Ying-Jey; Lin, Chia-Hao; Hwang, Pung-Pung

    2015-01-01

    Fish, like mammals, have to maintain their body fluid ionic and osmotic homeostasis through sophisticated iono-/osmoregulation mechanisms, which are conducted mainly by ionocytes of the gill (the skin in embryonic stages), instead of the renal tubular cells in mammals. Given the advantages in terms of genetic database availability and manipulation, zebrafish is an emerging model for research into regulatory and integrative physiology. At least five types of ionocytes, HR, NaR, NCC, SLC26, and KS cells, have been identified to carry out Na(+) uptake/H(+) secretion/NH4 (+) excretion, Ca(2+) uptake, Na(+)/Cl(-) uptake, K(+) secretion, and Cl(-) uptake/HCO3 (-) secretion, respectively, through distinct sets of transporters. Several hormones, namely isotocin, prolactin, cortisol, stanniocalcin-1, calcitonin, endothelin-1, vitamin D, parathyorid hormone 1, catecholamines, and the renin-angiotensin-system, have been demonstrated to positively or negatively regulate ion transport through specific receptors at different ionocytes stages, at either the transcriptional/translational or posttranslational level. The knowledge obtained using zebrafish answered many long-term contentious or unknown issues in the field of fish iono-/osmoregulation. The homology of ion transport pathways and hormone systems also means that the zebrafish model informs studies on mammals or other animal species, thereby providing insights into related fields. PMID:26600749

  10. [Review on the main microorganisms and their metabolic mechanisms in enhanced biological phosphorus removal (EBPR) systems].

    Science.gov (United States)

    Sun, Xue; Zhu, Wei-Jing; Wang, Liang; Wu, Wei-Xiang

    2014-03-01

    Enhanced biological phosphorus removal (EBPR) process is applied widely for removing phosphorus from wastewater. Studies on functional microorganisms and their metabolic mechanisms are fundamental to effective regulation for stable operation and performance improvement of EBPR process. Two main types of microorganisms in EBPR systems, polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were selected to summarize their metabolic mechanisms such as substrate uptake mechanisms, glycogen degradation pathways, extent of TCA cycle involvement and metabolic similarity between PAOs and GAOs. Application of molecular biology techniques in microbiology and metabolic mechanisms involved in the EBPR system was evaluated. Potential future research areas for the EBPR system and process optimization were also proposed. PMID:24984512

  11. Treatment of main heat transport system of Embalse Nuclear Power Plant with hydrazine at 150 deg C

    International Nuclear Information System (INIS)

    Ion exchange resins entrance to the main heat transport system of Embalse Nuclear Power Plant in April 1988 produced an increase of crud transport in the media, an increase of D2 evolution and mild steel corrosion rates. The removal of aggressive species from steady zones and a soft passivation of surfaces using hydrazine at moderate temperature, was recommended. The aim of this treatment was a partial dissolution of superficial defective oxides followed by the build up of a protective, homogeneous and adherent layer, to reduce generalized corrosion rate to historical values. The technique consisted of successive additions of the reagent solution to complete the prefixed amount, keeping a constant temperature of 150-152 deg C during 26 hours with continuous filtration through 1um mechanical filter, followed by a period at 180 deg C. Reagent addition was limited by ammonia concentration increase due to decomposition of hydrazine. Crud evolution was according to start up operation. Latter chemical control of the media consumes a 1000 litres resin bed. The results of this very soft treatment compatible with the start up operation of the plant, are very promising from the point of view that transported crud, deuterium concentration and corrosion rates decreased to the normal values before the mentioned event. (Author)

  12. Jaumann transport in relativistic continuum mechanics

    International Nuclear Information System (INIS)

    The Jaumann derivative of a tensor field in relativity is defined by a formal generalization of a stress rate in viscoelasticity. A tensor field is said to be Jaumann transported if its Jaumann derivative vanishes. It is found that the gravitational potentials are Jaumann transported identically. The concept of a ''complete rotation tensor'' has been introduced to study the Jaumann derivative with respect to a null vector field. This provides a characterization of the integrability of a hypersurface orthogonal congruence. A perfect fluid collapsing by neutrino emission and undergoing Jaumann transport with respect to the neutrino flow is found to be compatible with that of a catastrophic collapse. The circumstances leading to the existence of ''ghost neutrinos'' are cited. The degeneracy of the Kerr-Newmann black hole into the Reissner-Nordstrom black hole is expressed in terms of the Jaumann propagation. (author)

  13. Jaumann transport in relativistic continuum mechanics

    Science.gov (United States)

    Radhakrishna, L.; Katkar, L. N.; Date, T. H.

    1981-10-01

    We define the Jaumann derivative of a tensor field in relativity by a formal generalization of a stress rate in viscoelasticity. A tensor field is said to be Jaumann transported iff its Jaumann derivative vanishes. It is found that the gravitational potentials are Jaumann transported identically. The concept of a “complete rotation tensor” has been introduced to study the Jaumann derivative with respect to a null vector field. This provides a characterization of the integrability of a hypersurface orthogonal congruence. A perfect fluid collapsing by neutrino emission and undergoing Jaumann transport with respect to the neutrino flow is found to be compatible with that of a catastrophic collapse. The circumstances leading to the existence of “ghost neutrinos” are cited. The degeneracy of the Kerr-Newman black hole into the Reissner-Nordstrom black hole is expressed in terms of the Jaumann propagation.

  14. Jaumann transport in relativistic continuum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishna, L.; Katkar, L.N.; Date, T.H. (Shivaji Univ., Kolhapur (India). Dept. of Mathematics)

    1981-10-01

    The Jaumann derivative of a tensor field in relativity is defined by a formal generalization of a stress rate in viscoelasticity. A tensor field is said to be Jaumann transported if its Jaumann derivative vanishes. It is found that the gravitational potentials are Jaumann transported identically. The concept of a ''complete rotation tensor'' has been introduced to study the Jaumann derivative with respect to a null vector field. This provides a characterization of the integrability of a hypersurface orthogonal congruence. A perfect fluid collapsing by neutrino emission and undergoing Jaumann transport with respect to the neutrino flow is found to be compatible with that of a catastrophic collapse. The circumstances leading to the existence of ''ghost neutrinos'' are cited. The degeneracy of the Kerr-Newmann black hole into the Reissner-Nordstrom black hole is expressed in terms of the Jaumann propagation.

  15. Rupture mechanics of metallic alloys for hydrogen transport

    International Nuclear Information System (INIS)

    With the aim to establish a cheap hydrogen distribution system, the transport by pipelines is a solution particularly interesting. Among the high limit of elasticity steels, the X80 has been chosen for hydrogen transport. Its chemical composition and microstructure are given. Important microstructural changes have been revealed in the sheet thickness: the microstructure is thinner and richer in perlite in surface than in bulk. In parallel to this microstructural evolution, a microhardness gradient has been observed: the material microhardness is stronger in surface than in bulk of the sheet. The use of this material for hydrogen transport requires to study its resistance to hydrogen embrittlement. The main aim of this work is to develop an easy rupture mechanics test allowing to qualify the studied material in a gaseous hydrogen environment, to determine the sensitivity of the studied material to the hydrogen embrittlement and to better understand the mechanisms of the hydrogen embrittlement for ferritic materials. Two experimental tests have been used for: the first one is a traction machine coupled to an autoclave; the second one allows to carry out disk rupture tests. The toughness of the material in a gaseous hydrogen environment has thus been determined. The resistance of the material to hydrogen embrittlement has been characterized and by simulation, it has been possible to identify the areas with a strong concentration in hydrogen. The second aim of this work is to study the influence of the steel microstructure on the hydrogen position in the material and on the resistance of the material to the hydrogen embrittlement. The preferential trapping sites on the material not mechanically loaded have at first been identified, as well as the hydrogen position on the different phases and at the ferrite/cementite interface. The interaction between the mechanical loads, the position and the trapping of the hydrogen have been studied then. At last, has been established a link between the preferential localization of hydrogen and the results of the rupture mechanics tests in a gaseous hydrogen environment. (O.M.)

  16. Membrane transport mechanism 3D structure and beyond

    CERN Document Server

    Ziegler, Christine

    2014-01-01

    This book provides a molecular view of membrane transport by means of numerous biochemical and biophysical techniques. The rapidly growing number of atomic structures of transporters in different conformations and the constant progress in bioinformatics have recently added deeper insights.   The unifying mechanism of energized solute transport across membranes is assumed to consist of the conformational cycling of a carrier protein to provide access to substrate binding sites from either side of a cellular membrane. Due to the central role of active membrane transport there is considerable interest in deciphering the principles of one of the most fundamental processes in nature: the alternating access mechanism.   This book brings together particularly significant structure-function studies on a variety of carrier systems from different transporter families: Glutamate symporters, LeuT-like fold transporters, MFS transporters and SMR (RND) exporters, as well as ABC-type importers.   The selected examples im...

  17. Grain transport mechanics in shallow flow

    Science.gov (United States)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flows. The two-phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a dispe...

  18. Grain transport mechanics in shallow overland flow

    Science.gov (United States)

    A physical model based on continuum multiphase flow is described to represent saltating transport of grains in shallow overland flow. The two phase continuum flow of water and sediment considers coupled St.Venant type equations. The interactive cumulative effect of grains is incorporated by a disper...

  19. A Study on the Main Steam Safety Valve Opening Mechanism by Flashing on NPPs

    International Nuclear Information System (INIS)

    A safety injection event happened by opening of the Main Steam Safety Valve at Kori unit 1 on April 16, 2005. The safety valves were opened at the lower system pressure than the valve opening set point due to rapid system pressure drop by opening of the Power Operated Relief Valve installed at the upstream of the Main Steam System. But the opening mechanism of safety valve at the lower set point pressure was not explained exactly. So, it needs to be understood about the safety valve opening mechanism to prevent a recurrence of this kind of event at a similar system of Nuclear Power Plant. This study is aimed to suggest the hydrodynamic mechanism for the safety valve opening at the lower set point pressure and the possibility of the recurrence at similar system conditions through document reviewing for the related previous studies and Kori unit 1 event

  20. IMPROVEMENT OF FREIGHT TRANSPORTATION PROCESS AND THEIR MANAGEMENT MECHANISM

    Directory of Open Access Journals (Sweden)

    L. V. Martsenyuk

    2014-03-01

    Full Text Available Purpose. For Ukraine as for a post-socialist state there is an objective need of reforming on railway transport. In order to meet the requirements of consumers both within the country and outside of it, it is necessary to solve transport problems in time and to introduce new technologies, without lagging behind the developed European states. The purpose of this article is identification of problems in the process of freight transportations and development of ways of their overcoming, formation of the principles of economic efficiency increase for the use of freight cars using the improvement of management mechanism of freight transportations in the conditions of reforming. Methodology. Methods of strategic planning, system approach for research on improvement of the management mechanism of freight transportations, as well as the organizational-administrative method for structure of management construction were used in this research. Findings. Authors have explored the problems arising in the process of transportation of goods and measures, which will increase the efficiency of goods transportation. Advanced mechanism of freight transportation management for its application in the conditions of the railway transport reforming was developed. It is based on management centralization. Originality. The major factors, which slow down process of cargo transportations, are investigated in the article. The principles of management mechanism improvement of freight transportations are stated. They are based on association of commercial and car-repair activity of depots. All this will allow reducing considerably a car turn by decrease in duration of idle times on railway transport, increasing the speed of freight delivery and cutting down a transport component in the price of delivered production. Practical value. The offered measures will improve the efficiency of rolling stock use and increase cargo volumes turnover, promote links of Ukraine with neighboring countries.

  1. Statistical Mechanics of Collective Transport by Ants

    Science.gov (United States)

    Pinkoviezky, Itai; Gelblum, Aviram; Fonio, Ehud; Ghosh, Abhijit; Gov, Nir; Feinerman, Ofer

    Collective decisions and cooperation within groups are essential for the survival of many species. Conflicts within the group must be suppressed but conformism may render the system unresponsive to new information. Collective transport by ants is therefore an ideal model system to study how animal groups optimize these opposing requirements. We combine experiments and theory to characterize the collective transport. The ants are modeled as binary Ising spins, representing the two roles ants can perform during transport. It turns out that the ants poise themselves collectively near a critical point where the response to a newly attached ant is maximized. We identify the size as being proportional to an inverse effective temperature and thus the system can exhibit a mesoscopic transition between order and disorder by manipulating the size. Constraining the cargo with a string makes the system behave as a strongly non-linear pendulum. Theoretically we predict that a Hopf bifurcation occurs at a critical size followed by a global bifurcation where full swings emerge. Remarkably, these theoretical predictions were verified experimentally.

  2. Transport mechanisms in MoTe_{2-x} single crystals

    Science.gov (United States)

    Bonnet, A.; Conan, A.; Tregouet, Y.; Zoaeter, M.; Morsli, M.

    1991-05-01

    Transport coefficient measurements (electrical conductivity, thermoelectric power, Hall effect) have been performed on single crystals of MoTe{2-x} (x= 0.040 and 0.045). Experimental results are interpreted on the basis of a compensated p-type semiconductor model where donor and acceptor lacunar levels broaden in two energy bands. At low temperatures, the conduction mechanisms are mainly governed by a thermal hopping of carriers in these bands. At higher temperatures, the contribution of the extended states must be taken into account. MoTe{1,960} and MoTe{1,955} exhibit a quasi metallic behaviour which reflects the high delocalization of the electronic states in the broadened levels. Les mesures des coefficients de transport (conductivit lectrique, pouvoir thermolectrique, effet Hall ont t effectues sur des monocristaux de dans une gamme tendue de temprature. Les rsultats exprimentaux sont interprts sur la base d'un modle de semi-conducteur compens de type p niveaux largis d'origine lacunaire. A basse temprature les mcanismes de conduction sont principalement gouverns par des sauts activs thermiquement des porteurs dans le niveau accepteur largi. A plus haute temprature, la contribution des tats tendus doit tre prise en compte. MoTe{1,960} et MoTe{1,955} prsentent un comportement de type quasi mtallique associ la dlocalisation leve des tats lectroniques dans les niveaux largis.

  3. Directional auxin transport mechanisms in early diverging land plants

    OpenAIRE

    Viaene, Tom; Landberg, Katarina; Thelander, Mattias; Medvecka, Eva; Pederson, Eric; Feraru, Elena; Cooper, Endymion D.; Karimi, Mansour; Delwiche, Charles F.; Ljung, Karin; Geisler, Markus; Sundberg, Eva

    2015-01-01

    The emergence and radiation of multicellular land plants was driven by crucial innovations to their body plans [1]. The directional transport of the phytohormone auxin represents a key, plant-specific mechanism for polarization and patterning in complex seed plants [2, 3, 4 and 5]. Here, we show that already in the early diverging land plant lineage, as exemplified by the moss Physcomitrella patens, auxin transport by PIN transporters is operational and diversified into ER-localized and plasm...

  4. Quantum-mechanical wavepacket transport in quantum cascade laser structures

    OpenAIRE

    Lee, S. -C.; Banit, F.; Woerner, M.; Wacker, A.

    2005-01-01

    We present a viewpoint of the transport process in quantum cascade laser structures in which spatial transport of charge through the structure is a property of coherent quantum-mechanical wavefunctions. In contrast, scattering processes redistribute particles in energy and momentum but do not directly cause spatial motion of charge.

  5. Walking mechanism of the intracellular cargo transporter myosin V

    International Nuclear Information System (INIS)

    Motor proteins of the myosin, kinesin and dynein families transport vesicles and other cargo along tracks of actin filaments or microtubules through the cytoplasm of cells. The mechanism by which myosin V, a motor involved in several types of intracellular transport, moves processively along actin filaments, has recently been the subject of many single molecule biophysical studies. Details of the molecular mechanisms by which this molecular motor operates are starting to emerge

  6. Mechanical deformations in smectic-C main-chain liquid-crystalline elastomers

    OpenAIRE

    Snchez-Ferrer, Antoni; Finkelmann, Heino

    2009-01-01

    A novel crosslinked smectic-C Main-Chain Liquid-Crystalline Elastomer (MCLCE) has been synthesized by polycondensation of vinyloxy-terminated mesogens, tetramethyldisiloxane and pentamethylpentaoxapentasilecane. The introduction of the functional vinyloxy group allows the synthesis of well-defined networks having low soluble content and good mechanical properties. Networks having a macroscopic uniformly ordered director and a conical distribution of the smectic layer normal with respect to th...

  7. Charge Transport Mechanism in Thin Cuticles Holding Nandi Flame Seeds

    Directory of Open Access Journals (Sweden)

    Wycliffe K. Kipnusu

    2009-01-01

    Full Text Available Metal-sample-metal sandwich configuration has been used to investigate DC conductivity in 4 μm thick Nandi flame [Spathodea campanulata P. Beauv.] seed cuticles. J-V characteristics showed ohmic conduction at low fields and space charge limited current at high fields. Charge mobility in ohmic region was 4.06×10−5  (m2V−1s−1. Temperature-dependent conductivity measurements have been carried out in the temperature range 320 K 450 K. Activation energy within a temperature of 320 K–440 K was about 0.86 eV. Variable range hopping (VRH is the main current transport mechanism at the range of 330–440 K. The VRH mechanism was analyzed based on Mott theory and the Mott parameters: density of localized states near the Fermi-level N(EF≈9.04×1019  (eV−1cm−3 and hopping distance R≈1.44×10−7 cm, while the hopping energy (W was in the range of 0.72 eV–0.98 eV.

  8. TRANSPORT MECHANISM STUDIES OF CHITOSAN ELECTROLYTE SYSTEMS

    International Nuclear Information System (INIS)

    ABSTRACT: Knowledge of ion-conduction mechanisms in polymers is important for designing better polymer electrolytes for electrochemical devices. In this work, chitosan-ethylene carbonate/propylene carbonate (chitosan-EC/PC) system with lithium acetate (LiCH3COO) and lithium triflate (LiCF3SO3) as salts were prepared and characterized using electrochemical impedance spectroscopy to study the ion-conduction mechanism. It was found that the electrolyte system using LiCF3SO3 salt had a higher ionic conductivity, greater dielectric constant and dielectric loss value compared to system using LiCH3COO at room temperature. Hence, it may be inferred that the system incorporated with LiCF3SO3 dissociated more readily than LiCH3COO. Conductivity mechanism for the systems, 42 wt.% chitosan- 28 wt.% LiCF3SO3-30 wt.% EC/PC (CLT) and 42 wt.% chitosan-28 wt.% LiCH3COO-30 wt.% EC/PC (CLA) follows the overlapping large polaron tunneling (OLPT) model. Results show that the nature of anion size influences the ionic conduction of chitosan based polymer electrolytes. The conductivity values of the CLA system are found to be higher than that of CLT system at higher temperatures. This may be due to the vibration of bigger triflate anions would have hindered the lithium ion movements. FTIR results show that lithium ions can form complexation with polymer host which would provide a platform for ion hopping

  9. Structural basis for the mechanism of ABC transporters.

    Science.gov (United States)

    Beis, Konstantinos

    2015-10-01

    The ATP-binding cassette (ABC) transporters are primary transporters that couple the energy stored in adenosine triphosphate (ATP) to the movement of molecules across the membrane. ABC transporters can be divided into exporters and importers; importers mediate the uptake of essential nutrients into cells and are found predominantly in prokaryotes whereas exporters transport molecules out of cells or into organelles and are found in all organisms. ABC exporters have been linked with multi-drug resistance in both bacterial and eukaryotic cells. ABC transporters are powered by the hydrolysis of ATP and transport their substrate via the alternating access mechanism, whereby the protein alternates between a conformation in which the substrate-binding site is accessible from the outside of the membrane, outward-facing and one in which it is inward-facing. In this mini-review, the structures of different ABC transporter typesin different conformations are presented within the context of the alternating access mechanism and how they have shaped our current understanding of the mechanism of ABC transporters. PMID:26517899

  10. Structure and mechanism of ATP-binding cassette transporters

    Science.gov (United States)

    Locher, Kaspar P.

    2008-01-01

    ATP-binding cassette (ABC) transporters constitute a large superfamily of integral membrane proteins that includes both importers and exporters. In recent years, several structures of complete ABC transporters have been determined by X-ray crystallography. These structures suggest a mechanism by which binding and hydrolysis of ATP by the cytoplasmic, nucleotide-binding domains control the conformation of the transmembrane domains and therefore which side of the membrane the translocation pathway is exposed to. A basic, conserved two-state mechanism can explain active transport of both ABC importers and ABC exporters, but various questions remain unresolved. In this article, I will review some of the crystal structures and the mechanistic insight gained from them. Future challenges for a better understanding of the mechanism of ABC transporters will be outlined. PMID:18957379

  11. Mechanical energy transport. [during stellar turbulences

    Science.gov (United States)

    Stein, R. F.; Leibacher, J. W.

    1980-01-01

    The properties, generation, and dissipation mechanisms of acoustic, gravity and Alfven waves are described, whose restoring forces are pressure, buoyancy, and magnetic tension, respectively. For acoustic waves, generation by turbulent convective motions and by the Eddington Valve thermal overstability is discussed, considering the 'five-minute' oscillation; dissipation is possible either by radiation or shocks. Generation of gravity waves by penetrative convective motions and by shear arising from supergranule motions is reviewed, and dissipation due to wave breaking, interaction with the mean horizontal fluid flow, and very severe radiative damping is considered. Attention is given to Alfven wave generation by convective motions and thermal overstability, and to dissipation by mode coupling, wave decay, current dissipation, and particle collisions producing Joule or viscous heating.

  12. Main mechanisms of material properties degradation under reactor pressure vessel operating conditions

    International Nuclear Information System (INIS)

    In the process of NPP equipment operation materials are subjected to a prolonged influence of loads, associated with the variation of inner pressure and temperature under various conditions. Each equipment element damage is associated with some material fracture mechanism. For NPP equipment the mechanisms of irreversible damage accumulation are related with: irradiation embrittlement, thermal and strain aging, fatigue damages from mechanical and thermal loading, stress corrosion and fatigue corrosion, creep and thermal relaxation stresses, erosion and weak, thermal shock. The basic tasks of specialists working in the sphere of the provision of reliability and service life of nuclear power equipment are not only the determination of the main mechanisms of damages and reasons of their appearance, but also the study of methods which would permit to control these properties completely. By giving some examples of Russian NPP equipment with VVER-440 and VVER-1000 reactors the paper presents most typical degradation mechanisms of equipment material properties, including weldments, in the process of operation and methods to recover by using various technological means. (author)

  13. The alternating access mechanism of transport as observed in the sodium-hydantoin transporter Mhp1

    International Nuclear Information System (INIS)

    Crystal structures of a membrane protein transporter in three different conformational states provide insights into the transport mechanism. Secondary active transporters move molecules across cell membranes by coupling this process to the energetically favourable downhill movement of ions or protons along an electrochemical gradient. They function by the alternating access model of transport in which, through conformational changes, the substrate binding site alternately faces either side of the membrane. Owing to the difficulties in obtaining the crystal structure of a single transporter in different conformational states, relatively little structural information is known to explain how this process occurs. Here, the structure of the sodium-benzylhydantoin transporter, Mhp1, from Microbacterium liquefaciens, has been determined in three conformational states; from this a mechanism is proposed for switching from the outward-facing open conformation through an occluded structure to the inward-facing open state

  14. Controllable Lubrication for Main Engine Bearings Using Mechanical and Piezoelectric Actuators

    DEFF Research Database (Denmark)

    Estupinan, Edgar; Santos, Ilmar

    2012-01-01

    Although mechatronic systems are nowadays implemented in a large number of systems in vehicles, active lubrication systems are still incipient in industrial applications. This study is an attempt to extend the active lubrication concept to combustion engines and gives a theoretical contribution to...... this field. One refers to active lubrication when conventional hydrodynamic lubrication is combined with dynamically modified hydrostatic lubrication. In this study, two different schemes for the oil injection system in actively lubricated main engine bearings are presented. The use of active...... circumferentially located around the bearing surface. The main equations that govern the dynamics of the injection for a piezo-actuated oil injector and a mechanical-actuated oil injector are presented. It is shown how the dynamics of the oil injection system is coupled to the dynamics of the bearing fluid film...

  15. Increased oceanic heat transport in the main Atlantic inflow branch to the Nordic Seas 1993-2013

    Science.gov (United States)

    Hansen, Bogi; Margretha Larsen, Karin; Østerhus, Svein

    2015-04-01

    The flow of warm and saline water from the Atlantic Ocean, across the Greenland-Scotland Ridge, into the Nordic Seas - the Atlantic inflow - is split into three separate branches. The most intensive of these branches is the flow between Iceland and Faroes - the IF-inflow - which according to the latest estimates accounts for about half the total volume transport of the Atlantic inflow. The Atlantic inflow transports heat and salt into the Arctic region and is an integral part of the North Atlantic thermohaline circulation, projected to weaken during the 21st century, which might conceivably reduce the oceanic heat transport towards the Arctic. Since the late 1980s, the hydrographic properties of the IF-inflow have been monitored on regular CTD cruises along a section north from the Faroes and ADCPs have been moored on the section since the mid-1990s. From these in situ observations, time series of volume and heat transport have previously been reported, but the high variability of the heat transport has made identification of trends difficult. Here, we present the results from a new analysis of the IF-inflow where the in situ observations have been combined with data from satellite altimetry. The new time series show no indication of reduced volume transport and show a clear trend in heat transport. From 1993 to 2013, the heat transport relative to 0°C of the IF-inflow increased by more than 10%. This increase was mainly caused by increased temperatures of the inflow, which has been attributed to the weakening of the subpolar gyre, but small variations in the volume transport delayed the increase in heat transport so that it mainly occurred between 2003 and 2005.

  16. Transport mechanisms acting in toroidal devices: A theoretician's view

    International Nuclear Information System (INIS)

    Understanding the basic mechanisms of transport in toroidal confinement devices remains one of the more challenging scientific issues in magnetic confinement. At the same time, it is a critical issue for the magnetic fusion program. Recent progress in understanding fluctuations and transport has been fostered by the development and use of new diagnostics, bringing new perspectives on these studies. This has stimulated new theoretical developments. In this paper, a view of the most recent issues and progress in this area is given. The role of long wavelengths in core transport and the relation between shear flows and turbulence at the plasma edge are the primary topics considered in this paper

  17. [Genotypes and Main Effectors of Toxoplasma gondii and Their Pathogenic Mechanisms].

    Science.gov (United States)

    Shen, Ji-long; Wang, Lin

    2015-12-01

    Toxoplasma gondii is an intracellular Apicomplexan parasite that infects a wide range of warm blooded animals, including human, and has complex life cycle and pathogenic mechanisms. Although T. gondii is the only species recognized in the Toxoplasma genus, research on population genetic structure has shown its geographic genetic diversity. So far 232 genotypes have been identified by multilocus polymerase chain reaction-restriction fragment length polymorphism or microsatellite genotyping from both animals and human. T. gondii strains in North America typically possess types 2, 3 and 12 (found mainly in wild animals) clonal lineages, while types 2, 3, and 1 are common in Europe, and types 2 and 3 are common in Africa. These findings suggest a strongly clonal population structure in these regions. However, strains in South America are genetically more diverse, predominated by types Br I , Br II, Br III, and Br IV. Recent research has shown that the Chinese 1 (ToxoDB#9) genotype is dominantly circulating in the mainland of China, and shares the polymorphic ROP16I/III with types 1 and 3, and GRA15II with type 2. In this review, we summarized geographically the genotypes, host immune responses, and the pathogenic mechanisms of T. gondii strains, to provide basis for further research on genotype/effector-related pathogenic mechanism as well as biological and epidemiological studies of T. gondii. PMID:27089772

  18. ELECTRO-THERMAL AND MECHANICAL VALIDATION EXPERIMENT ON THE LHC MAIN BUSBAR SPLICE CONSOLIDATION

    CERN Document Server

    Willering, GP; Bourcey, N; Bottura, L; Charrondiere, M; Cerqueira Bastos, M; Deferne, G; Dib, G; Giloux, Chr; Grand-Clement, L; Heck, S; Hudson, G; Kudryavtsev, D; Perret, P; Pozzobon, M; Prin, H; Scheuerlein, Chr; Rijllart, A; Triquet, S; Verweij, AP

    2012-01-01

    To eliminate the risk of thermal runaways in LHC interconnections a consolidation by placing shunts on the main bus bar interconnections is proposed by the Task Force Splices Consolidation. To validate the design two special SSS magnet spares are placed on a test bench in SM-18 to measure the interconnection in between with conditions as close as possible to the LHC conditions. Two dipole interconnections are instrumented and prepared with worst-case-conditions to study the thermo-electric stability limits. Two quadrupole interconnections are instrumented and prepared for studying the effect of current cycling on the mechanical stability of the consolidation design. All 4 shunted interconnections showed very stable behaviour, well beyond the LHC design current cycle.

  19. Issues in tokamak/stellarator transport and confinement enhancement mechanisms

    International Nuclear Information System (INIS)

    At present, the mechanism for anomalous energy transport in low-β toroidal plasmas -- tokamaks and stellarators -- remains unclear, although transport by turbulent E x B velocities associated with nonlinear, fine-scale microinstabilities is a leading candidate. This article discusses basic theoretical concepts of various transport and confinement enhancement mechanisms as well as experimental ramifications which would enable one to distinguish among them and hence identify a dominant transport mechanism. While many of the predictions of fine-scale turbulence are born out by experiment, notable contradictions exist. Projections of ignition margin rest both on the scaling properties of the confinement mechanism and on the criteria for entering enhanced confinement regimes. At present, the greatest uncertainties lie with the basis for scaling confinement enhancement criteria. A series of questions, to be answered by new experimental/theoretical work, is posed to resolve these outstanding contradictions (or refute the fine-scale turbulence model) and to establish confinement enhancement criteria. 73 refs., 4 figs., 5 tabs

  20. Issues in tokamak/stellarator transport and confinement enhancement mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, F.W.

    1990-08-01

    At present, the mechanism for anomalous energy transport in low-{beta} toroidal plasmas -- tokamaks and stellarators -- remains unclear, although transport by turbulent E {times} B velocities associated with nonlinear, fine-scale microinstabilities is a leading candidate. This article discusses basic theoretical concepts of various transport and confinement enhancement mechanisms as well as experimental ramifications which would enable one to distinguish among them and hence identify a dominant transport mechanism. While many of the predictions of fine-scale turbulence are born out by experiment, notable contradictions exist. Projections of ignition margin rest both on the scaling properties of the confinement mechanism and on the criteria for entering enhanced confinement regimes. At present, the greatest uncertainties lie with the basis for scaling confinement enhancement criteria. A series of questions, to be answered by new experimental/theoretical work, is posed to resolve these outstanding contradictions (or refute the fine-scale turbulence model) and to establish confinement enhancement criteria. 73 refs., 4 figs., 5 tabs.

  1. Early metabolic effects and mechanism of ammonium transport in yeast

    International Nuclear Information System (INIS)

    Studies were performed to define the effects and mechanism of NH+4 transport in yeast. The following results were obtained. Glucose was a better facilitator than ethanol-H2O2 for ammonium transport; low concentrations of uncouplers or respiratory inhibitors could inhibit the transport with ethanol as the substrate. With glucose, respiratory inhibitors showed only small inhibitory effects, and only high concentrations of azide or trifluoromethoxy carbonylcyanide phenylhydrazone could inhibit ammonium transport. Ammonium in the free state could be concentrated approximately 200-fold by the cells. Also, the addition of ammonium produced stimulation of both respiration and fermentation; an increased rate of H+ extrusion and an alkalinization of the interior of the cell; a decrease of the membrane potential, as monitored by fluorescent cyanine; an immediate decrease of the levels of ATP and an increase of ADP, which may account for the stimulation of both fermentation and respiration; and an increase of the levels of inorganic phosphate. Ammonium was found to inhibit 86Rb+ transport much less than K+. Also, while K+ produced a competitive type of inhibition, that produced by NH4+ was of the noncompetitive type. From the distribution ratio of ammonium and the pH gradient, an electrochemical potential gradient of around -180 mV was calculated. The results indicate that ammonium is transported in yeast by a mechanism similar to that of monovalent alkaline cations, driven by a membrane potential. The immediate metabolic effects of this cation seem to be due to an increased [H+]ATPase, to which its transport is coupled. However, the carriers seem to be different. The transport system studied in this work was that of low affinity

  2. Charge carrier transport mechanisms in nanocrystalline indium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Forsh, E.A., E-mail: forsh_ea@nrcki.ru [National Research Center Kurchatov Institute, 123182 Moscow (Russian Federation); Faculty of Nano-, Bio-, Information and Cognitive Technologies, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Moscow Region (Russian Federation); Marikutsa, A.V. [Faculty of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Martyshov, M.N.; Forsh, P.A. [National Research Center Kurchatov Institute, 123182 Moscow (Russian Federation); Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Rumyantseva, M.N.; Gaskov, A.M. [Faculty of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Kashkarov, P.K. [National Research Center Kurchatov Institute, 123182 Moscow (Russian Federation); Faculty of Nano-, Bio-, Information and Cognitive Technologies, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Moscow Region (Russian Federation); Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow (Russian Federation)

    2014-05-02

    The charge transport properties of nanocrystalline indium oxide (In{sub 2}O{sub 3}) are studied. A number of nanostructured In{sub 2}O{sub 3} samples with various nanocrystal sizes are prepared by solgel method and characterized using various techniques. The mean nanocrystals size varies from 78 nm to 1820 nm depending on the conditions of their preparation. Structural characterizations of the In{sub 2}O{sub 3} samples are performed by means of transmission electron microscopy and X-ray diffraction. The analysis of dc and ac conductivity in a wide temperature range (T = 50300 K) shows that at high temperatures charge carrier transport takes place over conduction band and at low temperatures a variable range hopping transport mechanism can be observed. We find out that the temperature of transition from one mechanism to another depends on nanocrystal size: the transition temperature rises when nanocrystals are bigger in size. The average hopping distance between two sites and the activation energy are calculated basing on the analysis of dc conductivity at low temperature. Using random barrier model we show a uniform hopping mechanism taking place in our samples and conclude that nanocrystalline In{sub 2}O{sub 3} can be regarded as a disordered system. - Highlights: In{sub 2}O{sub 3} samples with various nanocrystal sizes are prepared by solgel method. The mean nanocrystal size varies from 78 nm to 1820 nm. At high temperatures charge carrier transport takes place over conduction band. At low temperatures a variable range hopping transport mechanism can be observed. We show a uniform hopping mechanism taking place in our samples.

  3. Increased coordination in public transport-which mechanisms are available?

    DEFF Research Database (Denmark)

    Sørensen, Claus Hedegaard; Longva, Frode

    2011-01-01

    After several years of New Public Management reforms within public transport, coordination seems to receive increased attention. With examples of actual as well as suggested changes taken from Denmark. Sweden and the UK the aim of the article is to analyse and classify the mechanisms utilized and...... mechanism has its strengths and failures. The article also debates to what extent the mechanisms conflict with three core characteristics of New Public Management: Unbundling of the public sector into corporatized units; more contract-based competitive provision; and greater emphasis on output controls...

  4. Increased coordination in public transport – which mechanisms are available?

    DEFF Research Database (Denmark)

    Sørensen, Claus Hedegaard; Longva, Frode

    2011-01-01

    After several years of New Public Management reforms within public transport, coordination seems to receive increased attention. With examples of actual as well as suggested changes taken from Denmark, Sweden and the UK the aim of the article is to analyse and classify the mechanisms utilized and...... mechanism has its strengths and failures. The article also debates to what extent the mechanisms conflict with three core characteristics of New Public Management: Unbundling of the public sector into corporatized units; more contract-based competitive provision; and greater emphasis on output controls....

  5. Structure and mechanism of ATP-dependent phospholipid transporters

    DEFF Research Database (Denmark)

    Lopez Marques, Rosa Laura; Poulsen, Lisbeth Rosager; Bailly, Aurélien; Geisler, Markus; Günther-Pomorski, Thomas; Palmgren, Michael Broberg

    2015-01-01

    Background ATP-binding cassette (ABC) transporters and P4-ATPases are two large and seemingly unrelated families of primary active pumps involved in moving phospholipids from one leaflet of a biological membrane to the other. Scope of review This review aims to identify common mechanistic features...... in the way phospholipid flipping is carried out by two evolutionarily unrelated families of transporters. Major conclusions Both protein families hydrolyze ATP, although they employ different mechanisms to use it, and have a comparable size with twelve transmembrane segments in the functional unit...

  6. Mechanical reliability of geometrically imperfect tubular oxygen transport membranes

    DEFF Research Database (Denmark)

    Kwok, Kawai; Frandsen, Henrik Lund; Søgaard, Martin; Hendriksen, Peter Vang

    2014-01-01

    Mixed ionic and electronic conductors have potential applications as oxygen transport membranes. Realization of the technology is challenged by mechanical reliability of the components which are subjected to stresses arising from oxygen stoichiometry gradients and external overpressure during...... operation. This paper investigates numerically the failure risk of tubular oxygen transport membranes under industrial operating conditions using finite element modeling and Weibull strength analysis. The effects of component manufacturing defects on fracture probability are elucidated by explicit modeling...... component quality (in terms of specification of tolerable deviation from perfect tubular shape) that allows fail-safe operation are deduced....

  7. Catalytic Mechanism of the Maltose Transporter Hydrolyzing ATP.

    Science.gov (United States)

    Huang, Wenting; Liao, Jie-Lou

    2016-01-12

    We use quantum mechanical and molecular mechanical (QM/MM) simulations to study ATP hydrolysis catalyzed by the maltose transporter. This protein is a prototypical member of a large family that consists of ATP-binding cassette (ABC) transporters. The ABC proteins catalyze ATP hydrolysis to perform a variety of biological functions. Despite extensive research efforts, the precise molecular mechanism of ATP hydrolysis catalyzed by the ABC enzymes remains elusive. In this work, the reaction pathway for ATP hydrolysis in the maltose transporter is evaluated using a QM/MM implementation of the nudged elastic band method without presuming reaction coordinates. The potential of mean force along the reaction pathway is obtained with an activation free energy of 19.2 kcal/mol in agreement with experiments. The results demonstrate that the reaction proceeds via a dissociative-like pathway with a trigonal bipyramidal transition state in which the cleavage of the ?-phosphate P-O bond occurs and the O-H bond of the lytic water molecule is not yet broken. Our calculations clearly show that the Walker B glutamate as well as the switch histidine stabilizes the transition state via electrostatic interactions rather than serving as a catalytic base. The results are consistent with biochemical and structural experiments, providing novel insight into the molecular mechanism of ATP hydrolysis in the ABC proteins. PMID:26666844

  8. Far SOL transport and main wall plasma interaction in DIII-D

    International Nuclear Information System (INIS)

    Far scrape-off layer (SOL) and near-wall plasma parameters in DIII-D depend strongly on the discharge parameters and confinement regime. In L-mode discharges cross-field transport increases with the average discharge density and flattens far SOL profiles, thus increasing plasma-wall contact. In H-mode between edge localized modes (ELMs), plasma-wall contact is generally weaker than in L-mode. During ELMs plasma fluxes to the wall increase to, or above the L-mode levels. Depending on the discharge conditions ELMs are responsible for 30-90% of the ion flux to the outboard chamber wall. Cross-field fluxes in far SOL are dominated by large amplitude intermittent transport events that may propagate all the way to the outer wall and cause sputtering. A Divertor Material Evaluation System (DiMES) probe containing samples of several ITER-relevant materials including carbon, beryllium and tungsten was exposed to a series of upper single null (USN) discharges as a proxy to measure the first wall erosion. (author)

  9. Co-current air-water flow in downward sloping pipes: Transport of capacity reducing gas pockets in wastewater mains:

    OpenAIRE

    Pothof, I.W.M.

    2011-01-01

    Air-water flow is an undesired condition in many systems for the transportation of water or wastewater. Air in storm water tunnels may get trapped and negatively affect the system. Air pockets in hydropower tunnels or sewers may cause blow-back events and inadmissible pressure spikes. Water pipes and wastewater pressure mains in particular are subject to air pocket formation in downward-sloping reaches, such as inverted siphons or terrain slopes. Air pocket accumulation causes energy losses a...

  10. Use of probabilistic design methods for NASA applications. [to be used in design phase of Space Transportation Main Engine

    Science.gov (United States)

    Safie, Fayssal M.

    1992-01-01

    This paper presents a reliability evaluation process designed to improve the reliability of advanced launch systems. The work performed includes the development of a reliability prediction methodology to be used in the design phase of the Space Transportation Main Engine (STME). This includes prediction techniques which use historical data bases as well as deterministic and probabilistic engineering models for predicting design reliability. In summary, this paper describes a probabilistic design approach for the next-generation liquid rocket engine, the STME.

  11. Microscopic chaos, fractals and transport in nonequilibrium statistical mechanics

    CERN Document Server

    Klages, Rainer

    2007-01-01

    A valuable introduction for newcomers as well as an important reference and source of inspiration for established researchers, this book provides an up-to-date summary of central topics in the field of nonequilibrium statistical mechanics and dynamical systems theory. Understanding macroscopic properties of matter starting from microscopic chaos in the equations of motion of single atoms or molecules is a key problem in nonequilibrium statistical mechanics. Of particular interest both for theory and applications are transport processes such as diffusion, reaction, conduction and viscosity. Recent advances towards a deterministic theory of nonequilibrium statistical physics are summarized: Both Hamiltonian dynamical systems under nonequilibrium boundary conditions and non-Hamiltonian modelings of nonequilibrium steady states by using thermal reservoirs are considered. The surprising new results include transport coefficients that are fractal functions of control parameters, fundamental relations between transp...

  12. Calcium transport in strongly calcifying laying birds: mechanisms and regulation.

    Science.gov (United States)

    Bar, Arie

    2009-04-01

    Birds that lay long clutches (series of eggs laid sequentially before a "pause day"), among them the high-producing, strongly-calcifying Gallus gallus domesticus (domestic hen) and Coturnix coturnix japonica (Japanese quail), transfer about 10% of their total body calcium daily. They appear, therefore, to be the most efficient calcium-transporters among vertebrates. Such intensive transport imposes severe demands on ionic calcium (Ca2+) homeostasis, and activates at least two extremely effective mechanisms for Ca2+ transfer from food and bone to the eggshell. This review focuses on the development, action and regulation of the mechanisms associated with paracellular and transcellular Ca2+ transport in the intestine and the eggshell gland (ESG); it also considers some of the proteins (calbindin, Ca2+ATPase, Na+/Ca2+ exchange, epithelial calcium channels (TRPVs), osteopontin and carbonic anhydrase (CA) associated with this phenomenon. Calbindins are discussed in some detail, as they appear to be a major component of the transcellular transport system, and as only they have been studied extensively in birds. The review aims to gather old and new knowledge, which could form a conceptual basis, albeit not a completely accepted one, for our understanding of the mechanisms associated with this phenomenon. In the intestine, the transcellular pathway appears to compensate for low Ca2+ intake, but in birds fed adequate calcium the major drive for calcium absorption remains the electrochemical potential difference (ECPD) that facilitates paracellular transport. However, the mechanisms involved in Ca2+ transport into the ESG lumen are not yet established. In the ESG, the presence of Ca2+-ATPase and calbindin--two components of the transcellular transport pathway--and the apparently uphill transport of Ca2+ support the idea that Ca2+ is transported via the transcellular pathway. However, the positive (plasma with respect to mucosa) electrical potential difference (EPD) in the ESG, among other findings, indicates that there may be major alternative or complementary paracellular passive transport pathways. The available evidence hints that the flow from the gut to the ESG, which occurs during a relatively short period (11 to 14 h out the 24- to 25.5-h egg cycle), is primarily driven by carbonic anhydrase (CA) activity in the ESG, which results in high HCO3(-) content that, in turn, "sucks out" Ca2+ from the intestinal lumen via the blood and ESG cells, and deposits it in the shell crystals. The increased CA activity appears to be dependent on energy input, whereas it seems most likely that the Ca2+ movement is secondary, that it utilizes passive paracellular routes that fluctuate in accordance with the appearance of the energy-dependent CA activity, and that the level of Ca2+ movement mimics that of the CA activity. The on-off signals for the overall phenomenon have not yet been identified. They appear to be associated with the circadian cycle of gonadal hormones, coupled with the egg cycle: it is most likely that progesterone acts as the "off" signal, and that the "on" signal is provided by the combined effect of an as-yet undefined endocrine factor associated with ovulation and with the mechanical strain that results from "egg white" formation and "plumping". This strain may initially trigger the formation of the mammillae and the seeding of shell calcium crystals in the isthmus, and thereafter initiate the formation of the shell in the ESG. PMID:19118637

  13. Mechanisms of Carrier Transport Induced by a Microswimmer Bath

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Andreas; Sokolov, Andrey; Aranson, Igor S.; Lowen, Hartmut

    2015-04-01

    Recently, it was found that a wedgelike microparticle (referred to as ”carrier”) which is only allowed to translate but not to rotate exhibits a directed translational motion along the wedge cusp if it is exposed to a bath of microswimmers. Here we model this effect in detail by resolving the microswimmers explicitly using interaction models with different degrees of mutual alignment. Using computer simulations we study the impact of these interactions on the transport efficiency of V-shaped carrier. We show that the transport mechanisms itself strongly depends on the degree of alignment embodied in the modelling of the individual swimmer dynamics. For weak alignment, optimal carrier transport occurs in the turbulent microswimmer state and is induced by swirl depletion inside the carrier. For strong aligning interactions, optimal transport occurs already in the dilute regime and is mediated by a polar cloud of swimmers in the carrier wake pushing the wedge-particle forward. We also demonstrate that the optimal shape of the carrier leading to maximal transport speed depends on the kind of interaction model used.

  14. Mechanisms of carrier transport induced by a microswimmer bath.

    Science.gov (United States)

    Kaiser, Andreas; Sokolov, Andrey; Aranson, Igor S; Lwen, Hartmut

    2015-04-01

    It was shown that a wedgelike microparticle (referred to as "carrier") exhibits a directed translational motion along the wedge cusp if it is exposed to a bath of microswimmers. Here we model this effect in detail by resolving the microswimmers explicitly using interaction models with different degrees of mutual alignment. Using computer simulations we study the impact of these interactions on the transport efficiency of a V-shaped carrier. We show that the transport mechanism itself strongly depends on the degree of alignment embodied in the modeling of the individual swimmer dynamics. For weak alignment, optimal carrier transport occurs in the turbulent microswimmer state and is induced by swirl depletion inside the carrier. For strong aligning interactions, optimal transport occurs already in the dilute regime and is mediated by a polar cloud of swimmers in the carrier wake pushing the wedge-particle forward. We also demonstrate that the optimal shape of the carrier leading to maximal transport speed depends on the kind of interaction model used. PMID:25347885

  15. Mechanism of copper transport from plasma to hepatocytes

    International Nuclear Information System (INIS)

    The effects of plasma components on the kinetics of copper transport by rat hepatocytes were examined in an attempt to determine how copper is mobilized from plasma for uptake by the liver. Specific protein-facilitated transport was indicated by saturation kinetics, competition by related substrates, and similar kinetic parameters for uptake and efflux. For copper uptake, K/sub m/ = 11 +/- 0.6 μM and V/sub max/ = 2.7 +/- 0.6 nmol Cu/(min x mg protein). Zinc is a competitive inhibitor of copper uptake, and copper competes for zinc uptake. Copper efflux from preloaded cells is biphasic. The kinetic parameters for the initial rapid phase are similar to the parameters for uptake. Copper transport by hepatocytes is strictly passive. A variety of metabolic inhibitors have no effect on uptake and initial rates are solely dependent on extracellular-intracellular concentration gradients. Albumin markedly inhibits copper intake by a substrate removal mechanism, and histidine facilitates albumin-inhibited copper uptake. The active species that delivers copper to hepatocytes under conditions of excess albumin and excess histidine is the His2Cu complex. Experiments with [3H]His264Cu showed that the transported species is free ionic copper. The kinetic parameters of copper transport by hepatocytes isolated from the brindled mouse model of Menkes' disease are normal. However, these cells show a decreased capacity to accumulate copper on prolonged incubation. An intracellular metabolic defect seems to be involved

  16. IDDTL: A Novel Identified Internet Data Transport Layer Mechanism

    Directory of Open Access Journals (Sweden)

    Yangyang Gao

    2014-01-01

    Full Text Available This paper proposes an identified data transport layer (IDDTL mechanism, which is implemented based on our present concepts of connection identifier (CID and CID additional information (CID-info. Since the fast evolved Internet scale and largely emerging various applications, especially with the new Internet architectures developed such as information centric network (ICN, the traditional end-to-end transport model has been exposed many defects in sorts of aspects, such as network management, flexibility and security. The novelty of the mechanism consists of two points: 1 it always conceals part of the communication information during the specific data transport process; 2 it splits the whole end-to-end communication process into two segments and forms a three-party and two-segment communication process model. Performance analysis shows that the mechanism could easily mitigate the problems such as distributed denial of service (D/DOS attacks and greatly improve the network management, flexibility and mobility. Furthermore, our simulation and test results demonstrate that IDDTL can be implemented with unique identifiers within an acceptable extra time cost of about 3.6 useconds compared with the traditional end-to-end model.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Cross-field plasma transport and main-chamber recycling in diverted plasmas on Alcator C-Mod

    International Nuclear Information System (INIS)

    Cross-field particle transport increases sharply with distance into the SOL and plays a dominant role in the 'main-chamber recycling' regime in Alcator C-Mod, a regime in which most of the plasma particle efflux recycles on the main-chamber walls rather than flows into the divertor volume. This observation has potentially important implications for a reactor: contrary to the ideal picture of divertor operation, a tightly baffled divertor may not offer control of the neutral density in the main-chamber such that charge exchange heat losses and sputtering of the main-chamber walls can be reduced. The conditions that give rise to the main-chamber recycling regime can be understood by considering the plasma-neutral particle balance: when the flux surface averaged neutral density exceeds a critical value, flows to the divertor can no longer compete with the ionization source and particle fluxes must increase with distance into the SOL. This critical neutral density condition can be recast into a critical cross-field plasma flux condition: particle fluxes must increase with distance into the SOL when the plasma flux crossing a given flux surface exceeds a critical value. Thus, the existence of the main-chamber recycling regime is intrinsically tied to the level of anomalous cross-field particle transport. Direct measurement of the effective cross-field particle diffusivities Deff in a number of ohmic L mode discharges indicates that Deff near the separatrix strongly increases as plasma collisionality increases. Convected heat fluxes correspondingly increase, implying that there exists a critical plasma density (or perhaps collisionality) beyond which no steady state plasma can be maintained, even in the absence of radiation. (author)

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

    Science.gov (United States)

    Dulermo, Rmi; Gamboa-Melndez, Heber; Ledesma-Amaro, Rodrigo; Thvenieau, 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, ?Ylpxa1 ?Ylpxa2 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 ?Ylpxa1 ?Ylpxa2 ?Ylant1 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

  20. Design and manufacture of JOYO MK-III heat transport system components. Main dump heat exchangers

    International Nuclear Information System (INIS)

    The MK-III project has three major purposes such: increasing high neutron flux, improvement of plant availability factor and upgrading in irradiation techniques. The reactor thermal power was increased from 100 MWt to 140 MWt along with the increase of fast neutron flux. The plant concept of the cooling system to increase the heat removal capability was decided in 1991. The main components in the cooling system such as intermediate heat exchangers (IHXs) and dump heat exchangers (DHXs) were designed and manufactured based on the plant concept of the cooling system. These component replacements were safely carried out from October 30, 2000 to September 21, 2001. System function tests of the cooling system, the performance tests, were carried out from June 2003 as the last phase of the MK-III modification work. During the performance tests, the reactor power was raised step by step, while confirming the nuclear and thermal characteristics of the MK-III core and the heat removal capability of IHXs and DHXs. After the performance tests, the MK-III license was granted by the government in November 2003. The new DHX for MK-III with 35 MWt heat exchange rate was installed in the same location where the old one was installed, so the MK-III DHX was installed in the same location where the old one was installed, so the MK-III DHX was designed with almost the same geometry as the old one. The design was carefully reviewed for thermal hydraulics, pressure loss, flow induced vibration etc. During the design of the MK-III DHX, the following problems were evaluated. (1) Securing the appropriate heat removal capability margin. (2) Measures to increase the installed load associated with increase of the heat transfer area. (3) Measures to increase the air side pressure loss (Design optimization of the main air blower). (4) Improvement of the maintenance performance based on the maintenance experience of the old DHX. After the design study and modification work of the MK-III DHX, the system faction and the performance tests were carried out. As a result of these tests, it was confirmed that the performance of the MK-III DHX satisfied the design. This report describes the specific characteristics in the design and manufacturing, the design data and principles of the design for the MK-III DHX. (author)

  1. Diffusion and the dislocation sweeping mechanism for hydrogen transport

    International Nuclear Information System (INIS)

    A mechanism for H diffusion in metals is proposed. The mechanism for hydrogen transport or sweeping by dislocations has a number of features which invite discussion. A feature which is of some importance is that the pressures calculated in voids due to the sweeping of hydrogen to the voids are not maximum values since ideal gas conditions were assumed. It also reflects a choice of reasonable rather than maximizing values of the parameters. The sweeping mechanism predicts that voids or inclusions can be pressurized by hydrogen, which in turn can account for the much-observed reductions in the ductility of ductile alloys. Similarly, the sweeping of hydrogen to grain boundaries can also result in insidious embrittlement through the loss of cohesion

  2. Design and manufacture of JOYO MK-III heat transport system. Main Intermediate heat exchanger

    International Nuclear Information System (INIS)

    The MK-III project to improve the irradiation capability of the experimental fast reactor JOYO have been in underway. The MK-III project has three major purposes such as increasing high neutron flux, improvement of plant availability factor and upgrading in irradiation techniques. The increase of fast neutron flux and the enlargement of that field increase the reactor thermal rate from 100 MWt to 140 MWt. The main components in the cooling system such as intermediate heat exchangers (IHXs) and dump heat exchangers (DHXs) were replaced in MK-III modification in order to increase heat removal capability. These components replacement has been safely carried out from October 30, 2000 to September 21, 2001. The new IHX that has 70 MWt rated heat exchange rate was installed to the location where old one was installed, so the mew IHX was designed with almost same geometry as old one. The design was carefully reviewed on structural integrity, shielding performance, thermal hydraulics, pressure loss, flow induced vibration and component design criterion and earthquake-proof class. A newly developed stainless steel named 316FR was adopted as a major structure material of the new IHX. The 316FR was developed for usage of sodium cooled fast reactor and has improved creep rupture and creep fatigue strength, In the design the following problems to be solved were cleared, These problems arise from defect of old IHX, increase of temperature difference between outlet and inlet and increase of sodium flow rate. (1) Reduction of ineffective flow to increase the heat transfer efficiency. (2) Suppression of CP (Corrosion Products) adhesion. (3) To prevent falling down of sodium free surface accompanied by increase of sodium flow. (4) Mitigation of thermal transient. This report describes the specific characteristic in the design and manufacturing, design data and principle of the design for the new IHX. The design was proved on above mentioned problem (3) by measurement of sodium free surface level up to the MK-II sodium flow rate during the comprehensive function test from February to March, 2003. The design adequacy for problem (1) and (4) will be confirmed in performance test. The CP adhesion will be investigated through long term operation. (author)

  3. Analysis of River Sea Transport in the Direction of the Danube Black Sea and the Danube Rhine River River Main

    Directory of Open Access Journals (Sweden)

    S. o?kic

    2014-12-01

    Full Text Available Development of the river sea transport is directly related to the characteristics of waterway network which enables navigation between river basins and seas. Inland waterways in Serbia belong to the Danube navigational system. There are two navigational directions: Danube East and Danube West. River-sea transport can be directly established in these directions between the Serbian international ports on the Danube (Apatin, Novi Sad, Belgrade, Pan?evo, Smederevo and Prahovo. Development of the Pan-European Corridor VII and the River Danube-Black Sea and Danube-Rhine-Main region would allow not only in Serbia but also in neighbouring states and all over Europe connection with the sea. In this paper the technical and exploitation characteristics of the river Danube will be analysed in terms of the navigation of various river and sea vessels with different exploitation characteristics.

  4. Inner nuclear membrane protein transport is mediated by multiple mechanisms.

    Science.gov (United States)

    Zuleger, Nikolaj; Korfali, Nadia; Schirmer, Eric C

    2008-12-01

    Work in the nuclear transport field has led to an incredibly detailed description of protein translocation through the central channel of the nuclear pore complex, yet the mechanism by which nuclear envelope transmembrane proteins reach the inner nuclear membrane after synthesis in the endoplasmic reticulum is still hotly debated. Three different translocation models have gained experimental support: (i) simple lateral diffusion through the nuclear envelope membrane system; (ii) translocation by vesicle fusion events; and (iii) a variation on classical transport mediated by the nuclear pore complex. Although these models appear to be mutually exclusive, in the present paper we argue that they probably all function for different inner nuclear membrane proteins according to their unique characteristics. PMID:19021558

  5. Mechanical Fatigue Testing of High Burnup Fuel for Transportation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-05-01

    This report describes testing designed to determine the ability of high burnup (HBU) (>45 GWd/MTU) spent fuel to maintain its integrity under normal conditions of transportation. An innovative system, Cyclic Integrated Reversible-bending Fatigue Tester (CIRFT), has been developed at Oak Ridge National Laboratory (ORNL) to test and evaluate the mechanical behavior of spent nuclear fuel (SNF) under conditions relevant to storage and transportation. The CIRFT system is composed of a U-frame equipped with load cells for imposing the pure bending loads on the SNF rod test specimen and measuring the in-situ curvature of the fuel rod during bending using a set up with three linear variable differential transformers (LVDTs).

  6. Mechanical transport in two-dimensional networks of fractures

    International Nuclear Information System (INIS)

    The objectives of this research are to evaluate directional mechanical transport parameters for anisotropic fracture systems, and to determine if fracture systems behave like equivalent porous media. The tracer experiments used to measure directional tortuosity, longitudinal geometric dispersivity, and hydraulic effective porosity are conducted with a uniform flow field and measurements are made from the fluid flowing within a test section where linear length of travel is constant. Since fluid flow and mechanical transport are coupled processes, the directional variations of specific discharge and hydraulic effective porosity are measured in regions with constant hydraulic gradients to evaluate porous medium equivalence for the two processes, respectively. If the fracture region behaves like an equivalent porous medium, the system has the following stable properties: (1) specific discharge is uniform in any direction and can be predicted from a permeability tensor; and (2) hydraulic effective porosity is directionally stable. Fracture systems with two parallel sets of continuous fractures satisfy criterion 1. However, in these systems hydraulic effective porosity is directionally dependent, and thus, criterion 2 is violated. Thus, for some fracture systems, fluid flow can be predicted using porous media assumptions, but it may not be possible to predict transport using porous media assumptions. Two discontinuous fracture systems were studied which satisfied both criteria. Hydraulic effective porosity for both systems has a value between rock effective porosity and total porosity. A length-density analysis (LDS) of Canadian fracture data shows that porous media equivalence for fluid flow and transport is likely when systems have narrow aperture distributions. 54 references, 90 figures, 7 tables

  7. Mechanism of travelling-wave transport of particles

    International Nuclear Information System (INIS)

    Numerical and experimental investigations have been carried out on transport of particles in an electrostatic travelling field. A three-dimensional hard-sphere model of the distinct element method was developed to simulate the dynamics of particles. Forces applied to particles in the model were the Coulomb force, the dielectrophoresis force on polarized dipole particles in a non-uniform field, the image force, gravity and the air drag. Friction and repulsion between particle-particle and particle-conveyer were included in the model to replace initial conditions after mechanical contacts. Two kinds of experiments were performed to confirm the model. One was the measurement of charge of particles that is indispensable to determine the Coulomb force. Charge distribution was measured from the locus of free-fallen particles in a parallel electrostatic field. The averaged charge of the bulk particle was confirmed by measurement with a Faraday cage. The other experiment was measurements of the differential dynamics of particles on a conveyer consisting of parallel electrodes to which a four-phase travelling electrostatic wave was applied. Calculated results agreed with measurements, and the following characteristics were clarified. (1) The Coulomb force is the predominant force to drive particles compared with the other kinds of forces, (2) the direction of particle transport did not always coincide with that of the travelling wave but changed partially. It depended on the frequency of the travelling wave, the particle diameter and the electric field, (3) although some particles overtook the travelling wave at a very low frequency, the motion of particles was almost synchronized with the wave at the low frequency and (4) the transport of some particles was delayed to the wave at medium frequency; the majority of particles were transported backwards at high frequency and particles were not transported but only vibrated at very high frequency

  8. Mechanical seals qualification procedure of the main pumps of nuclear power plants in France

    International Nuclear Information System (INIS)

    Many important pumps in the nuclear power plants are equipped with mechanical seals. The good behaviour and reliability of mechanical seals depend specially on the quality and the stability of an interface of several microns. Peripheral speed reaches 50 m/s and pressure 5 MPa, shaft diameter may be 200 mm. Any failure of the mechanical seals may stop the production of electricity or may compromise nuclear safety. As far back as 1970, EDF has conducted qualification actions for the most important mechanical seals in terms of availability and safety. A qualification of mechanical seals needs three steps: - constructor test (tuning) at normal conditions, -qualification test on test rig at EDF/DER (semi-industrial) at normal, exceptional and incidental conditions lasting about 1500 h, - industrial qualification test in nuclear power station over one year. Several supplying sources are absolutely necessary. Any pump may receive mechanical seals from at least two different suppliers. A compromise had to be found to restrict the suppliers' number down to three. This choice concerned three high technology suppliers. A consistent modification procedure had been developed (references file procedure). For each power plant series, about ten types of mechanical seals are concerned. The selection criteria are the higher loads factors P, Vg or the safety related importance. This expensive approach is useful for EDF, many functional failures have been detected before the serial mechanical seals installation in the power plants. (authors). 1 annexe

  9. THE ORGANIZATIONAL-ECONOMIC MECHANISM OF DEVELOPMENT OF RAILWAY TRANSPORT ENTERPRISES

    OpenAIRE

    Plugina, J.

    2011-01-01

    The article highlighted the organizational-economic mechanism of development of railway transport enterprises, its components (organizational and economic mechanisms) and are defined and their essence is opened.

  10. The Bear Brook Watershed in Maine (BBWM) at 25: manipulation, monitoring, mechanism, and modeling

    Czech Academy of Sciences Publication Activity Database

    Norton, S. A.; Fernandez, I. J.; Navrátil, Tomáš; Simon, K. S.; Jain, S.

    Northport : University of Maine, 2012 - (Fernandez, I.; Norton, S.; Wilson, T.). s. 177-177 ISBN 978-0-87723-108-0. [BIOGEOMON : international symposium on ecosystem behavior /7./. 15.07.2012-20.07.2012, Northport] Institutional support: RVO:67985831 Keywords : geochemistry * monitoring * modeling Subject RIV: DD - Geochemistry

  11. New mechanism for the control of sodium transport in wheat

    International Nuclear Information System (INIS)

    Full text: Durum and other tetraploid wheats are typically very salt-sensitive compared to hexaploid bread wheats. This is primarily due to high rates of Na+ accumulation in the leaves in tetraploid wheat. Recently, we have discovered a durum landrace with low Na+ accumulation and enhanced K+/Na+ discrimination, much lower than current durum cultivars and similar to bread wheat. We have identified 3 different mechanisms for the control of Na+ transport to the leaves in this landrace, 1) control of Na+ uptake at the epidermis of the root, 2) control of Na+ loading into the xylem and 3) partitioning of Na+ into the leaf sheath. The low Na+ durum landrace had 3-4 fold lower Na+ uptake rates than durum cultivars. Using X ray microanalysis on snap-frozen root sections, we found Na+ to be high in the epidermis, a decreasing gradient through the cortex, low in the endodermis and again high in the stele (pencycle and xylem parenchyma), indicative of control points at the epidermis and in the stele. Partitioning of Na+ between shoot and root was at least 5 times lower in the durum landrace, suggestive of greater control of Na+ transport at the site of xylem loading. A third and novel control mechanism was found in the leaf sheath. Short and long term salinity treatments showed that Na+ was partitioned preferentially into the sheaths of the low Na+ durum landrace, keeping leaf blade Na+ levels very low and similar to that of bread wheat Na+ partitioned in the leaf sheath was stored primarily in the parenchyma cells and Cl- in the epidermal cells. Collectively, these data show that we have identified germplasm that has the potential to increase the salt tolerance of durum wheat. Additionally, as bread wheat does not contain the mechanism for partitioning Na+ into the sheath, this trait may be useful for further increasing the salt tolerance of this species

  12. Mechanical Forces Impair Alveolar Ion Transport Processes A Putative Mechanism Contributing to the Formation of Pulmonary Edema

    OpenAIRE

    Fronius, Martin

    2012-01-01

    The aim of this chapter is to highlight the importance of transepithelial ion transport processes for lung function in general and to focus on the impact of mechanical forces on pulmonary ion transport in particular. Linking mechanical forces with pulmonary ion transport derives from the fact that the lung is a dynamic organ as well as from several studies providing evidence that the amount of mechanical forces as used during artificial ventilation correlates with mortality rates in patients...

  13. High-Performance Concurrency Control Mechanisms for Main-Memory Databases

    CERN Document Server

    Larson, Per-Åke; Diaconu, Cristian; Freedman, Craig; Patel, Jignesh M; Zwilling, Mike

    2012-01-01

    A database system optimized for in-memory storage can support much higher transaction rates than current systems. However, standard concurrency control methods used today do not scale to the high transaction rates achievable by such systems. In this paper we introduce two efficient concurrency control methods specifically designed for main-memory databases. Both use multiversioning to isolate read-only transactions from updates but differ in how atomicity is ensured: one is optimistic and one is pessimistic. To avoid expensive context switching, transactions never block during normal processing but they may have to wait before commit to ensure correct serialization ordering. We also implemented a main-memory optimized version of single-version locking. Experimental results show that while single-version locking works well when transactions are short and contention is low performance degrades under more demanding conditions. The multiversion schemes have higher overhead but are much less sensitive to hotspots ...

  14. Mechanical analysis of the main bus bars in the DFBA shuffling modules

    CERN Document Server

    Ramos, D

    2012-01-01

    The main bus bars (13 kA) inside the shuffling modules of the distribution feed boxes powering the LHC arcs (DFBA) are subjected to high Lorentz forces. The structural behaviour of the bus bars under such forces is here analysed. The results are discussed with respect to a risk of structural failure due to excessive deformation or degradation of the electrical insulation by repeated contact with other surfaces.

  15. High-Performance Concurrency Control Mechanisms for Main-Memory Databases

    OpenAIRE

    Larson, Per-Åke; Blanas, Spyros; Diaconu, Cristian; Freedman, Craig; Patel, Jignesh M; Zwilling, Mike

    2011-01-01

    A database system optimized for in-memory storage can support much higher transaction rates than current systems. However, standard concurrency control methods used today do not scale to the high transaction rates achievable by such systems. In this paper we introduce two efficient concurrency control methods specifically designed for main-memory databases. Both use multiversioning to isolate read-only transactions from updates but differ in how atomicity is ensured: one is optimistic and one...

  16. Approaching the Shockley-Queisser limit: General assessment of the main limiting mechanisms in photovoltaic cells

    International Nuclear Information System (INIS)

    In principle, the upper efficiency limit of any solar cell technology can be determined using the detailed-balance limit formalism. However, “real” solar cells show efficiencies which are always below this theoretical value due to several limiting mechanisms. We study the ability of a solar cell architecture to approach its own theoretical limit, using a novel index introduced in this work, and the amplitude with which the different limiting mechanisms affect the cell efficiency is scrutinized as a function of the electronic gap and the illumination level to which the cell is submitted. The implications for future generations of solar cells aiming at an improved conversion of the solar spectrum are also addressed

  17. Cellular Transport Mechanisms of Cytotoxic Metallodrugs: An Overview beyond Cisplatin

    Directory of Open Access Journals (Sweden)

    Sarah Spreckelmeyer

    2014-09-01

    Full Text Available The field of medicinal inorganic chemistry has grown consistently during the past 50 years; however, metal-containing coordination compounds represent only a minor proportion of drugs currently on the market, indicating that research in this area has not yet been thoroughly realized. Although platinum-based drugs as cancer chemotherapeutic agents have been widely studied, exact knowledge of the mechanisms governing their accumulation in cells is still lacking. However, evidence suggests active uptake and efflux mechanisms are involved; this may be involved also in other experimental metal coordination and organometallic compounds with promising antitumor activities in vitro and in vivo, such as ruthenium and gold compounds. Such knowledge would be necessary to elucidate the balance between activity and toxicity profiles of metal compounds. In this review, we present an overview of the information available on the cellular accumulation of Pt compounds from in vitro, in vivo and clinical studies, as well as a summary of reports on the possible accumulation mechanisms for different families of experimental anticancer metal complexes (e.g., Ru Au and Ir. Finally, we discuss the need for rationalization of the investigational approaches available to study metallodrug cellular transport.

  18. Na+-stimulated phosphate uptake system in Synechocystis sp. PCC 6803 with Pst1 as a main transporter

    Directory of Open Access Journals (Sweden)

    Burut-Archanai Surachet

    2011-10-01

    Full Text Available Abstract Background Most living cells uptake phosphate, an indispensable nutrient for growth from their natural environment. In Synechocystis sp. PCC 6803, the cells lack phosphate-inorganic transport (Pit system but contain two phosphate-specific transport (Pst systems, Pst1 and Pst2. We investigated the kinetics of Pi uptake of these two Pst systems by constructing the two mutants, ΔPst1 and ΔPst2, and comparing their kinetic properties with those of the wild-type cells under both Pi-sufficient and deficient conditions. The effects of pH and Na+ on the uptake of phosphate in Synechocystis were also studied. Results Growth rates of the two mutants and wild type were similar either under phosphate-sufficient or deficient condition. The Km for phosphate uptake was 6.09 μM in wild type and this was reduced to 0.13 μM in ΔPst1 cells and 5.16 μM in the ΔPst2 strain. The Vmax values of 2.48, 0.22, and 2.17 μmol • (min • mg of chlorophyll a-1 were obtained for wild type, the ΔPst1 and ΔPst2 strains, respectively. A monophasic phosphate uptake was observed in wild-type cells. The uptake of phosphate was energy and pH-dependent with a broad pH optimum between pH 7-10. Osmolality imposed by NaCl stimulated phosphate uptake whereas that imposed by sorbitol decreased uptake, suggesting stimulation of uptake was dependent upon ionic effects. Conclusion The data demonstrate that Pst2 system of Synechocystis has higher affinity toward phosphate with lower Vmax than Pst1 system. The Pst1 system had similar Km and Vmax values to those of the wild type suggesting that Pst1 is the main phosphate transporter in Synechocystis sp. PCC 6803. The Km of Pst1 of Synechocystis is closer to that of Pit system than to that of the Pst system of E. coli, suggesting that Synechocystis Pst1 is rather a medium/low affinity transporter whereas Pst2 is a high affinity transporter.

  19. Correlation of microstructure and thermo-mechanical properties of a novel hydrogen transport membrane

    Science.gov (United States)

    Zhang, Yongjun

    A key part of the FutureGen concept is to support the production of hydrogen to fuel a "hydrogen economy," with the use of clean burning hydrogen in power-producing fuel cells, as well as for use as a transportation fuel. One of the key technical barriers to FutureGen deployment is reliable and efficient hydrogen separation technology. Most Hydrogen Transport Membrane (HTM) research currently focuses on separation technology and hydrogen flux characterization. No significant work has been performed on thermo-mechanical properties of HTMs. The objective of the thesis is to understand the structure-property correlation of HTM and to characterize (1) thermo mechanical properties under different reducing environments and thermal cycles (thermal shock), and (2) evaluate the stability of the novel HTM material. A novel HTM cermet bulk sample was characterized for its physical and mechanical properties at both room temperature and at elevated temperature up to 1000°C. Micro-structural properties and residual stresses were evaluated in order to understand the changing mechanism of the microstructure and its effects on the mechanical properties of materials. A correlation of the microstructural and thermo mechanical properties of the HTM system was established for both HTM and the substrate material. Mechanical properties of both selected structural ceramics and the novel HTM cermet bulk sample are affected mainly by porosity and microstructural features, such as grain size and pore size-distribution. The Young's Modulus (E-value) is positively correlated to the flexural strength for materials with similar crystallographic structure. However, for different crystallographic materials, physical properties are independent of mechanical properties. Microstructural properties, particularly, grain size and crystallographic structure, and thermodynamic properties are the main factors affecting the mechanical properties at both room and high temperatures. The HTM cermet behaves more like an elastic material at room temperature and as a ductile material at temperature above 850°C. The oxidation and the plasticity of Pd phase mainly affected the mechanical properties of HTM cermet at high temperature, also as a result of thermal cycling. Residual stress induced in the HTM by thermo cycles also plays a very critical role in defining the thermo-mechanical properties.

  20. [Dynamic hyperinflation -- the main mechanism of decreased exercise tolerance in patients with COPD].

    Science.gov (United States)

    Gologanu, Daniela

    2013-01-01

    Decreased exercise tolerance in patients with COPD is the result of involvement in variable proportion of three mechanisms: ventilatory limitation, muscle dysfunction and cardio-vascular involvement (inadequate intake of oxygen at tissue level). Ventilatory limitation is caused by the combination of increased demand and decreased ventilatory capacity Increased ventilatory demand is the result of exercise worsening of ventilation-perfusion imbalance, and decreased ventilatory capacity is the result of decreased elastic recoil and dynamic obstruction. The consequence is the expiratory flowlimitation, leading to inefficientexpiratory muscle activity and dynamic hyperinflation. Dynamic hyperinflation is a result of structural abnormalities in COPD producing mechanical disorders that limit ventilation. Dynamic hyperinflation has some beneficial effects by facilitating maximal exhalation. Negative effects ofhyperinflation are: (1) decreased tidal volume ability to grow properly at exercise, which causes mechanical ventilatorlimitation; (2) decreased functional capacity of inspiratory musles (by increasing elastic load with respiratory muscle fatigue and increase work ofbreathing); (3) exercise hypoxemia and carbon dioxide retention; (4) impairmentof cardiac function during exercise by decreasing venous return and cardiac output. Evaluation of pulmonary hyperinflation is a useful tool for better characterizing the effects of disease and for monitoring the response of therapeutic interventions on exercise tolerance of patients with COPD. PMID:23894791

  1. Tunnelling effect enhanced by lattice screening as main cold fusion mechanism: An brief theoretical overview

    International Nuclear Information System (INIS)

    In this paper are illustrated the main features of tunneling traveling between two deuterons within a lattice. Considering the screening effect due lattice electrons we compare the d-d fusion rate evaluated from different authors assuming different screening efficiency and different d-d potentials. Then, we propose a effective potential which describe very well the attractive contribute due to plasmon exchange between two deuterons and by means of it we will compute the d-d fusion rates for different energy values. Finally the good agreement between theoretical and experimental results proves the reality of cold fusion phenomena and the reliability of our model

  2. The present status of vacuum system of J-PARC main ring and 3-50 beam transport

    International Nuclear Information System (INIS)

    The vacuum system of J-PARC Main Ring synchrotron and 3-50 beam transport line were successfully developed in April 2008 and still progress synchronously with the accelerator study phases such as the injection, the acceleration, the fast extraction to the abort line, the slow extraction to the hadron laboratory, fast extraction to the neutrino line, and, also the remodeling of coil wiring of sextupole magnets in this summer. In the simple ducts of the arc section, a vacuum pressure is going down to about 2e-7 Pa so that the pumps are expected to be long life, otherwise, the vacuum chamber of in-vacuum magnets such as the injection or fast-extraction septum magnets with lamination cores keeps high pressure of over 1e-5 Pa by outgassing from huge surface area. The pumps at that chambers will die in a few years. (author)

  3. Correlation between magnetic field quality and mechanical components of the Large Hadron Collider main dipoles

    Energy Technology Data Exchange (ETDEWEB)

    Bellesia, B

    2006-12-15

    The 1234 superconducting dipoles of the Large Hadron Collider, working at a cryogenic temperature of 1.9 K, must guarantee a high quality magnetic field to steer the particles inside the beam pipe. Magnetic field measurements are a powerful way to detect assembly faults that could limit magnet performances. The aim of the thesis is the analysis of these measurements performed at room temperature during the production of the dipoles. In a large scale production the ideal situation is that all the magnets produced were identical. However all the components constituting a magnet are produced with certain tolerance and the assembly procedures are optimized during the production; due to these the reality drifts away from the ideal situation. We recollected geometrical data of the main components (superconducting cables, coil copper wedges and austenitic steel coil collars) and coupling them with adequate electro-magnetic models we reconstructed a multipolar field representation of the LHC dipoles defining their critical components and assembling procedures. This thesis is composed of 3 main parts: 1) influence of the geometry and of the assembling procedures of the dipoles on the quality of the magnetic field, 2) the use of measurement performed on the dipoles in the assembling step in order to solve production issues and to understand the behaviour of coils during the assembling step, and 3) a theoretical study of the uncertain harmonic components of the magnetic field in order to assess the dipole production.

  4. Correlation between magnetic field quality and mechanical components of the Large Hadron Collider main dipoles

    International Nuclear Information System (INIS)

    The 1234 superconducting dipoles of the Large Hadron Collider, working at a cryogenic temperature of 1.9 K, must guarantee a high quality magnetic field to steer the particles inside the beam pipe. Magnetic field measurements are a powerful way to detect assembly faults that could limit magnet performances. The aim of the thesis is the analysis of these measurements performed at room temperature during the production of the dipoles. In a large scale production the ideal situation is that all the magnets produced were identical. However all the components constituting a magnet are produced with certain tolerance and the assembly procedures are optimized during the production; due to these the reality drifts away from the ideal situation. We recollected geometrical data of the main components (superconducting cables, coil copper wedges and austenitic steel coil collars) and coupling them with adequate electro-magnetic models we reconstructed a multipolar field representation of the LHC dipoles defining their critical components and assembling procedures. This thesis is composed of 3 main parts: 1) influence of the geometry and of the assembling procedures of the dipoles on the quality of the magnetic field, 2) the use of measurement performed on the dipoles in the assembling step in order to solve production issues and to understand the behaviour of coils during the assembling step, and 3) a theoretical study of the uncertain harmonic components of the magnetic field in order to assess the dipole production

  5. Mechanisms of calcium transport in small intestine. Final report

    International Nuclear Information System (INIS)

    The vitamin D hormone, 1,25-dihydroxyvitamin D3, was demonstrated to be the prime hormonal agent regulating intestinal absorption of divalent cations. Production of the vitamin D hormone is, in turn, regulated by parathyroid hormone, low dietary calcium, low plasma phosphorus, and is suppressed by 1,25-dihydroxyvitamin D3, by high plasma phosphorus, high plasma calcium, and the absence of parathyroid hormone. A variety of analogs of the vitamin D hormone were prepared. In addition, the preparation of radiolabeled vitamin D hormone was accomplished using chemical synthesis, and this highly radioactive substance was found to localize in the nuclei of the intestinal villus cells that promote intestinal absorption of calcium. A receptor for the vitamin D hormone was also located, and the general mechanism of response to the vitamin D hormone included the binding to a receptor molecule, transfer to the nucleus, transcription of specific genes followed by translation to transport proteins. Methods were developed for the discovery of the appropriate gene products that play a role in calcium transport

  6. Flexible Mechanical Conveyors for Regolith Extraction and Transport

    Science.gov (United States)

    Walton, Otis R.; Vollmer, Hubert J.

    2013-01-01

    A report describes flexible mechanical conveying systems for transporting fine cohesive regolith under microgravity and vacuum conditions. They are totally enclosed, virtually dust-free, and can include enough flexibility in the conveying path to enable an expanded range of extraction and transport scenarios, including nonlinear drill-holes and excavation of enlarged subsurface openings without large entry holes. The design of the conveyors is a modification of conventional screw conveyors such that the central screw-shaft and the outer housing or conveyingtube have a degree of bending flexibility, allowing the conveyors to become nonlinear conveying systems that can convey around gentle bends. The central flexible shaft is similar to those used in common tools like a weed whacker, consisting of multiple layers of tightly wound wires around a central wire core. Utilization of compliant components (screw blade or outer wall) increases the robustness of the conveying, allowing an occasional oversized particle to pass hough the conveyor without causing a jam or stoppage

  7. Sensitivity of the Static Earthquake Triggering Mechanism to Elastic Heterogeneity and Main Event Slip

    CERN Document Server

    Maharramov, Musa

    2013-01-01

    This paper has evolved out of our previous work on static stress transfer, where we used the full-space elastostatic Green's tensor to compute the Coulomb stress transfer impact of the Landers earthquake on the Hector Mine event. In this work, we use the elastostatic Green's tensor for an arbitrary layered Earth model with free-surface boundary conditions to study the impact of elastic heterogeneity as well as source-fault slip and geometry on the stress transfer mechanism. Slip distribution and fault geometry of the source have a significant impact on the stress transfer, especially in case of spatially extended triggered events. Maximization of the Coulomb stress transfer function for known aftershocks provides a mechanism for inverting for the source event slip. Heterogeneity of the elastic earth parameters is shown to have a sizeable, but lower-magnitude, impact on the static stress transfer in 3D. The analysis is applied to Landers/Hector Mine and 100 small "aftershocks" of the Landers event. A computati...

  8. Mechanically induced chemiluminescence from polymers incorporating a 1,2-dioxetane unit in the main chain

    Science.gov (United States)

    Chen, Yulan; Spiering, A. J. H.; Karthikeyan, S.; Peters, Gerrit W. M.; Meijer, E. W.; Sijbesma, Rint P.

    2012-07-01

    Nature uses mechanochemical transduction processes to achieve diverse and vital functions, such as hearing, cellular adhesion and gating of ion channels. One fascinating example of biological mechanotransduction is the emission of light on mechanical stimulation. However, molecular-level transduction of force into luminescence in a synthetic system remains a challenge. Here, we show that bis(adamantyl)-1,2-dioxetane emits visible light when force is applied to a polymer chain or network in which this unit is incorporated. Bright-blue luminescence was observed on sonication of solutions of dioxetane-containing linear polymers and on the straining of polymer networks with dioxetane crosslinkers. Light is emitted from the adamantanone-excited state that forms on opening of the four-membered dioxetane ring. Increased sensitivity and colour tuning were achieved by energy transfer to suitable acceptors. High spatial and temporal resolutions highlight the potential to study the failure of polymeric materials in unprecedented detail.

  9. [The main pathophysiological mechanisms of kidney injury in obstructive sleep apnea syndrome].

    Science.gov (United States)

    Zelveian, P A; Dgerian, L G

    2014-01-01

    Nowadays, obstructive sleep apnea syndrome (OSAS) has been established to promote both structural and functional changes in the kidneys. The basis for these changes is pathophysiological mechanisms, such as hyperproduction of free radicals and disruption of NO-mediated vasodilator responses, activation of the sympathetic autonomic nervous system and the renin-angiotensin-aldosterone system, endothelial dysfunction, development of renal venous hypertension, and stimulation of atrial natriuretic peptide production, which in turn results in increased intraglomerular pressure and glomerular hyperfiltration. In patients with OSAS, the kidneys may be damaged by OSAS-related abnormalities, such as hypertension, diabetes mellitus, metabolic syndrome, erythrocytosis, atherosclerosis, and cor pulmonale, which may also lead to kidney injury under isolated conditions and, when concurrent OSAS is present, may even aggravate the existing kidney injury. PMID:25095664

  10. Decoupling Mechanical and Ion Transport Properties in Polymer Electrolyte Membranes

    Science.gov (United States)

    McIntosh, Lucas D.

    Polymer electrolytes are mixtures of a polar polymer and salt, in which the polymer replaces small molecule solvents and provides a dielectric medium so that ions can dissociate and migrate under the influence of an external electric field. Beginning in the 1970s, research in polymer electrolytes has been primarily motivated by their promise to advance electrochemical energy storage and conversion devices, such as lithium ion batteries, flexible organic solar cells, and anhydrous fuel cells. In particular, polymer electrolyte membranes (PEMs) can improve both safety and energy density by eliminating small molecule, volatile solvents and enabling an all-solid-state design of electrochemical cells. The outstanding challenge in the field of polymer electrolytes is to maximize ionic conductivity while simultaneously addressing orthogonal mechanical properties, such as modulus, fracture toughness, or high temperature creep resistance. The crux of the challenge is that flexible, polar polymers best-suited for polymer electrolytes (e.g., poly(ethylene oxide)) offer little in the way of mechanical robustness. Similarly, polymers typically associated with superior mechanical performance (e.g., poly(methyl methacrylate)) slow ion transport due to their glassy polymer matrix. The design strategy is therefore to employ structured electrolytes that exhibit distinct conducting and mechanically robust phases on length scales of tens of nanometers. This thesis reports a remarkably simple, yet versatile synthetic strategy---termed polymerization-induced phase separation, or PIPS---to prepare PEMs exhibiting an unprecedented combination of both high conductivity and high modulus. This performance is enabled by co-continuous, isotropic networks of poly(ethylene oxide)/ionic liquid and highly crosslinked polystyrene. A suite of in situ, time-resolved experiments were performed to investigate the mechanism by which this network morphology forms, and it appears to be tied to the disordered structure observed in diblock polymer melts near the order-disorder transition. In the resulting solid PEMs, the conductivity and modulus are both high, exceeding the 1 mS/cm and approaching the 1 GPa metrics, respectively, often cited for lithium-metal batteries. In the final chapter, an alternative synthetic route to generate nanostructured PEMs is presented. This strategy relies on the formation of a thermodynamically stable network morphology exhibited by a triblock terpolymer prepared with crosslinking moieties along the backbone. Although the mechanical properties of the resulting PEM are excellent, the conductivity is found to be somewhat limited by network defects that result from the solvent-casting procedure.

  11. The role of lock-in mechanisms in transition processes: the case of energy for road transport

    OpenAIRE

    Klitkou, Antje; Bolwig, Simon; Hansen, Teis; Wessberg, Nina

    2015-01-01

    This paper revisits the theoretical concepts of lock-in mechanisms to analyse transition processes in energy production and road transportation in the Nordic countries, focussing on three technology platforms: advanced biofuels, e-mobility and hydrogen and fuel cell electrical vehicles. The paper is based on a comparative analysis of case studies. The main lock-in mechanisms analysed are learning effects, economies of scale, economies of scope, network externalities, informational increasing ...

  12. CLUB FORMATION MECHANISM FOR TRANSPORT-COMMUNITY CREDIT CARDS

    Science.gov (United States)

    Ding, Yue; Kobayashi, Kiyoshi; Nishida, Junji; Yoshida, Mamoru

    In this paper, the roles of transport-community cards jointly issued by a public transport firm and retails are investigated as a means to vitalize an obsolescence shopping center located in a middle of a city. When both the price of goods supplied by the retails and the transport fares affect the consumers' behavior, there exist pecuniary externality between the behaviors of the retails and transport firms. The introduction of a transport-community cards system enables to integrate a basket of goods and transport service into a single commodity; thus, the pecuniary externality can be internalized by price coordination. In addition, the paper clarifies theoretically that the transport firm initiatively decides the price of the transportation service and the retails transfer their incomes to the transport firm so that they are induced to jointly issue the transport-community cards.

  13. Intracellular loop 5 is important for the transport mechanism and molecular pharmacology of the human serotonin transporter

    DEFF Research Database (Denmark)

    Said, Saida; Neubauer, Henrik Amtoft; Müller, Heidi Kaastrup; Sinning, Steffen

    2015-01-01

    . Understanding the molecular mechanism of inhibition and which structural elements are involved in inhibitor binding and conformational changes of the transporter will provide clues for the development of improved drugs for the treatment of depression. Guided by our previous studies, we combined different......-over rate of SERT for 5-HT transport. We also find that the potency of antidepressants is improved by in SERT with a lengthened IL5. These findings support the notion that intracellular loops are important substructures with a role in both the transport mechanism and molecular pharmacology of SERT.......The serotonin transporter (SERT) belongs to a family of transport proteins called the neurotransmitter:sodium symporters. The specialized members of this family transport different neurotransmitters across the cell membrane, thereby regulating signaling between neurons. Most of these transporters...

  14. Atlantic surfclam connectivity within the Middle Atlantic Bight: Mechanisms underlying variation in larval transport and settlement

    Science.gov (United States)

    Zhang, Xinzhong; Munroe, Daphne; Haidvogel, Dale; Powell, Eric N.

    2016-05-01

    Larval transport and settlement have been shown in various studies to be essential in determining population abundance and connectivity for benthic invertebrates. This transport is influenced by both the physical environment and biological behavior. The Atlantic surfclam, Spisula solidissima, is a commercially important benthic invertebrate fishery species along the U.S northeastern coast. In this study, a physical circulation model is coupled to a surfclam larval model to investigate the dynamics of larval transport and settlement within the Middle Atlantic Bight (MAB) shelf in 2006. The main physical mechanisms causing variability in larval transport and settlement are also examined. Model results show that surfclam larvae released from July to early October experience relatively larger settlement rates, due to higher average temperatures experienced by larvae. Larval along-shore transport exhibits a mean down-coast pattern following the coastal current from the northeast to the southwest, with most high-frequency (period of 2-10 days) variations caused by fluctuations in the along-shore surface wind stress, and with seasonal variations speculated to be driven mainly by changes in the across-shelf density gradient. Larval across-shelf movement is highly correlated with the along-shore surface wind stress mediated by coastal upwelling and downwelling episodes, but the correlation is further dependent on the vertical distribution of the larvae, particularly their position relative to the thermocline. Most surfclam larvae released from the Middle Atlantic shelf stay below the thermocline and experience a net onshore transport during the summer-stratified season when upwelling-favorable wind forcing dominates. A proposed critical value of water temperature at the thermocline successfully regulates the observed patterns of vertical distribution of surfclam larvae and their across-shelf movement off the New Jersey and South Virginia shelves; that is, when the water temperature at the thermocline is above the critical value (19.0 °C), surfclam larvae tend to escape the warm surface layer to concentrate below the thermocline and follow the across-shelf movement of bottom water, and vice versa. These results provide an important insight into the general mechanism of how physical environmental factors interact with biological behavior of the larvae to influence larval transport, connectivity and population dynamics, and also indicate the potential impact of large-scale climate change on benthic species and coastal ecosystems.

  15. Mechanism and regulation of phosphate transport in Streptococcus pyogenes

    International Nuclear Information System (INIS)

    In contrast to results reported with other bacteria, uptake of 32Pi in Streptococcus pyogenes was found to occur rapidly in starved cultures and to be strongly and immediately inhibited by addition of exogenous glycolytic energy sources (such as glucose) and nonglycolytic sources of ATP (such as arginine). Preincubation of starved cells with NaF, iodoacetate, or arsenate eliminated the inhibiting effect of glucose but not that of arginine. In accordance with the hypothesis that transport was attributable to P/sub i/-P/sub i/ exchange, uptake and efflux of 32P/sub i/ in the presence of trans unlabeled P/sub i/ exhibited similar characteristics and were largely eliminated by reduction of the trans P/sub i/ concentration. Neither process was inhibited appreciably by pretreatment of cells with ionophores or metabolic inhibitors, but both processes were abolished by exposure to p-chloromercuribenzoate. Inhibition by both exogenous energy sources resulted in a reduction in the maximal velocity of transport (V/sub max/). Whereas arginine also caused a shift in the apparent Michaelis-Menten constant (K/sub m/) to larger values, glucose did not alter the K/sub m/. On the basis of the results reported, it is proposed that the rate of P/sub i/ exchange is determined positively by the intracellular and extracellular concentrations of P/sub i/ and negatively by ATP or metabolites thereof. The mechanism of ATP action is unknown but could involve either covalent or noncovalent modification of the carrier protein

  16. Ethanol as a fuel for road transportation. Main report; Contribution to IEA Implementing Agreement on Advanced Motor Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, Ulrik; Johansen, T.; Schramm, J.

    2009-05-15

    Bioethanol as a motor fuel in the transportation sector, mainly for road transportation, has been subject to many studies and much discussion. Furthermore, the topic involves not only the application and engine technical aspects, but also the understanding of the entire life cycle of the fuel, well-to-wheels, including economical, environmental, and social aspects. It is not, however, the aim of this report to assess every single one of these aspects. The present report aims to address the technical potential and problems as well as the central issues related to the general application of bioethanol as an energy carrier in the near future. In discussions of the advantages and drawbacks of ethanol, the type of application is important. Generalization is not possible, because ethanol can be used in many forms. Furthermore, a wide range of ethanol/gasoline blends has not yet been investigated sufficiently. The most favorable type of application is determined by infrastructural factors, especially vehicle fleet configuration. From a technical point of view, optimal usage involves a high degree of water content in the ethanol, and this excludes low-percentage-ethanol fuels. The benefits seem strongly related to the amount of ethanol in a given blend, that is, the more the better. Both engine efficiencies and emissions improve with more ethanol in the fuel. Wet ethanol constitutes an even cleaner fuel in both the production and application phases. In summary, ethanol application has many possibilities, but with each type of application comes a set of challenges. Nevertheless, technical solutions for each challenge are available. (ln)

  17. Comparative study of chemo-electro-mechanical transport models for an electrically stimulated hydrogel

    International Nuclear Information System (INIS)

    The main objective of this work is to introduce a new expression for the hydrogel’s hydration for use within the Poisson Nernst–Planck chemo electro mechanical (PNP CEM) transport models. This new contribution to the models support large deformation by considering the higher order terms in the Green–Lagrangian strain tensor. A detailed discussion of the CEM transport models using Poisson Nernst–Planck (PNP) and Poisson logarithmic Nernst–Planck (PLNP) equations for chemically and electrically stimulated hydrogels will be presented. The assumptions made to simplify both CEM transport models for electric field application in the order of 0.833 kV m−1 and a highly diluted electrolyte solution (97% is water) will be explained. This PNP CEM model has been verified accurately against experimental and numerical results. In addition, different definitions for normalizing the parameters are used to derive the dimensionless forms of both the PNP and PLNP CEM. Four models, PNP CEM, PLNP CEM, dimensionless PNP CEM and dimensionless PNLP CEM transport models were employed on an axially symmetric cylindrical hydrogel problem with an aspect ratio (diameter to thickness) of 175:3. The displacement and osmotic pressure obtained for the four models are compared against the variation of the number of elements for finite element analysis, simulation duration and solution rate when using the direct numerical solver. (papers)

  18. Transport mechanism of 11C-labeled L- and D-methionine in human-derived tumor cells

    International Nuclear Information System (INIS)

    Introduction: S-methyl-11C-labeled L- and D-methionine (11C-L- and D-MET) are useful as radiotracers for tumor imaging. However, it is not known whether the transport mechanism of 11C-D-MET is the same as that for 11C-L-MET, which is transported by the amino acid transport system L. In this study, we investigated the transport mechanism of 11C-L- and D-MET by analyzing the expression of transport system genes in human-derived tumor cells. Methods: The expression of transport system genes in human-derived tumor cells was quantitatively analyzed. The mechanism of MET transport in these cells was investigated by incubating the cells with [S-methyl-3H]-L-MET (3H-L-MET) or [S-methyl-3H]-D-MET (3H-D-MET) and the effect of 2-amino-2- norbornane-carboxylic acid, a system L transport inhibitor, or α-(methylamino)isobutyric acid, a system A transport inhibitor, on their transport was measured. The transport and metabolic stability of [S-methyl-14C]-L-MET (14C-L-MET) and 3H-D-MET was also analyzed using bearing mice with H441 or PC14 tumor cells. Results: 3H-D-MET was mainly transported by both systems L and alanine–serine–cysteine (ASC), while system L was involved in 3H-L-MET transport. There was a high correlation between both 3H-L-MET and 3H-D-MET uptake and the expression of amino acid transport system genes. In the in vivo study, H441-cell accumulation of 3H-D-MET was higher than that of 14C-L-MET. Hepatic and renal accumulation of 3H-D-MET was lower than that of 14C-L-MET. Conclusion: The transport mechanism of 3H-D-MET was different from that of 3H-L-MET. Since 3H-D-MET has high metabolic stability, its accumulation reflects the transporter function of system L and ASC.

  19. Qinshan CANDU 6 main heat transport system high accuracy performance tracking in support of regional overpower protection

    International Nuclear Information System (INIS)

    This paper deals with the Qinshan CANDU 6 main Heat Transport System (HTS) high accuracy performance tracking/adjustment up to about 7 years of operation in support of Regional Overpower Protection (ROP). Operational and aging related changes of the HTS throughout its lifetime may lead to restrictions in certain safety system settings and hence some restriction in performance under certain conditions. A step in confirming safe reactor operation is the tracking of relevant data and their corresponding interpretation by the use of appropriate thermalhydraulic analytic models. Analytic predictions, in association with an optimized parameter tracking and adjustment methodology, confirm continued safe reactor operation. This paper demonstrates that Qinshan CANDU Unit 1, as compared to other CANDU 6 nuclear reactors of earlier design, continues to exhibit significantly improved performance with much reduced plant aging effects. This paper further demonstrates the high accuracy of the advanced performance tracking and adjustment methodology and applies it to Qinshan CANDU Unit 1, ensuring and demonstrating the continued excellent performance of the reference analytic models. The analytic methodology as well as the advanced performance tracking and analysis methodology can also beneficially be applied to both new and refurbished CANDU type nuclear reactors. (author)

  20. Time-resolved Mechanism of Extracellular Gate Opening and Substrate Binding in a Glutamate Transporter*S?

    OpenAIRE

    Shrivastava, Indira H.; Jiang, Jie; Amara, Susan G.; Bahar, Ivet

    2008-01-01

    Glutamate transporters, also referred to as excitatory amino acid transporters (EAATs), are membrane proteins that regulate glutamatergic signal transmission by clearing excess glutamate after its release at synapses. A structure-based understanding of their molecular mechanisms of function has been elusive until the recent determination of the x-ray structure of an archaeal transporter, GltPh. GltPh exists as a trimer, with each subunit containing a core region that m...

  1. Mechanical transport and porous media equivalence in anisotropic fracture networks

    International Nuclear Information System (INIS)

    The objective of this work is to investigate the directional characteristics of hydraulic effective porosity in an effort to understand porous medium equivalence for continuous and discontinuous fracture systems. Continuous systems contain infinitely long fractures. Discontinuous systems consist of fractures with finite lengths. The distribution of apertures (heterogeneity) has a major influence on the degree of porous medium equivalence for distributed continuous and discontinuous systems. When the aperture distribution is narrow, the hydraulic effective porosity is slightly less than the total porosity for continuous systems, and greater than the rock effective porosity for discontinuous systems. However, when heterogeneity is significant, the hydraulic effective porosity is directionally dependent and greater than total porosity for both systems. Non-porous medium behavior ws found to differ for distributed continuous systems and for continuous systems with parallel sets. For the latter systems, hydraulic effective porosity abruptly decreases below total porosity in those particular directions where the hydraulic gradient and the orientation of a fracture set are orthogonal. The results for the continuous systems with parallel sets also demonstrate that a system that behaves like a continuum for fluid flux may not behave like a continuum for mechanical transport. 3 references, 13 figures

  2. Dissecting the molecular mechanisms of intraflagellar transport in Chlamydomonas

    DEFF Research Database (Denmark)

    Pedersen, L. B.; Geimer, S.; Rosenbaum, J. L.

    2006-01-01

    Background The assembly and maintenance of eukaryotic cilia and flagella are mediated by intraflagellar transport (IFT), a bidirectional microtubule (MT)-based transport system. The IFT system consists of anterograde (kinesin-2) and retrograde (cDynein1b) motor complexes and IFT particles compris...

  3. Corrosion is the main mechanism of material loss at the taper junction of large head metal on metal hip replacements

    OpenAIRE

    Matthies, A.K.; Racasan, Radu; Bills, Paul J.; Panagiotidou, A.; Blunt, Liam; Skinner, J.; Blunn, G.; A.J. Hart

    2012-01-01

    Material loss at the head-stem taper junction may contribute to the high early failure rates of stemmed large head metal-on-metal (LH-MOM) hip replacements. We sought to quantify both wear and corrosion and by doing so determine the main mechanism of material loss at the taper. This was a retrospective study of 78 patients having undergone revision of a LH-MOM hip replacement. All relevant clinical data was recorded. Corrosion was assessed using light microscopy and scanning electron microsco...

  4. Main results on modeling of primary water stress corrosion cracking at control rod drive mechanism nozzles of pressurized water reactors

    International Nuclear Information System (INIS)

    One of the main failure mechanisms that cause risks to pressurized water reactors is the primary water stress corrosion cracking occurring at the control reactor displacement mechanism nozzles. It is caused by the joint effect of tensile stress, temperature, susceptible metallurgical microstructure and environmental conditions of the primary water. These cracks can cause accidents that reduce nuclear safety and reduce the reliability. The objective of this work is to propose the modeling of these cracks, for prediction of the initiation and propagation of them, and to validate it according with the experimental resulting and the literature in a nickel-based Alloy 600. The experimental data were obtained at CDTN-Brazilian Nuclear Technology Development Center, in a recent installed SSRT- slow strain rate testing equipment. It had been used tensile specimens not pre-cracked, made in Alloy 600 MA (mill annealed). In this paper was presented obtained models, experimental method used to its validation and conclusions. (author)

  5. Main results on modeling of primary water stress corrosion cracking at control rod drive mechanism nozzles of pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Aly, Omar F.; Andrade, Arnaldo H.P. de; Mattar Neto, Miguel [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: ofaly@ipen.br; aandrade@ipen.br; mmattar@ipen.br; Schvartzman, Monica M.A.M. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)]. E-mail: monicas@cdtn.br

    2007-07-01

    One of the main failure mechanisms that cause risks to pressurized water reactors is the primary water stress corrosion cracking occurring at the control reactor displacement mechanism nozzles. It is caused by the joint effect of tensile stress, temperature, susceptible metallurgical microstructure and environmental conditions of the primary water. These cracks can cause accidents that reduce nuclear safety and reduce the reliability. The objective of this work is to propose the modeling of these cracks, for prediction of the initiation and propagation of them, and to validate it according with the experimental resulting and the literature in a nickel-based Alloy 600. The experimental data were obtained at CDTN-Brazilian Nuclear Technology Development Center, in a recent installed SSRT- slow strain rate testing equipment. It had been used tensile specimens not pre-cracked, made in Alloy 600 MA (mill annealed). In this paper was presented obtained models, experimental method used to its validation and conclusions. (author)

  6. Structural mechanics research and development for main components of Chinese 300 MWe PWR NPPs: from design to life management

    International Nuclear Information System (INIS)

    Qinshan Nuclear Power Plant (Unit I), is a 300 MWe prototype PWR independently developed by Chinese own efforts, from design, manufacture, construction, installation, commissioning, to operation, inspection, maintenance, ageing management and lifetime assessment. Shanghai Nuclear Engineering Research and Design Institute (SNERDI) has taken up with and involved in deeply the R and D to tackle problems of this type of reactor since very beginning in early 1970s. Structural mechanics is one of the important aspects to ensure the safety and reliability for NPP components. This paper makes a summary on role of structural mechanics for component safety and reliability assessment in different stages of design, commissioning, operation, as well as lifetime assessment on this type PWR NPPs, including Qinshan-I and Chashma-I, a sister plant in Pakistan designed by SNERDI. The main contents of the paper cover design by analysis for key components of NSSS; mechanical problems relating to safety analysis; special problems relating to pressure retaining components, such as fracture mechanics, sealing analysis and its test verifications, etc.; experimental research on flow-induced vibration; seismic qualification for components; component failure diagnosis and root cause analysis; vibration qualification and diagnosis technique; component online monitoring technique; development of defect assessment; methodology of aging management and lifetime assessment for key components of NPPs, etc. (authors)

  7. Mechanism of transport modulation by an extracellular loop in an archaeal excitatory amino acid transporter (EAAT) homolog.

    Science.gov (United States)

    Mulligan, Christopher; Mindell, Joseph A

    2013-12-01

    Secondary transporters in the excitatory amino acid transporter family terminate glutamatergic synaptic transmission by catalyzing Na(+)-dependent removal of glutamate from the synaptic cleft. Recent structural studies of the aspartate-specific archaeal homolog, Glt(Ph), suggest that transport is achieved by a rigid body, piston-like movement of the transport domain, which houses the substrate-binding site, between the extracellular and cytoplasmic sides of the membrane. This transport domain is connected to an immobile scaffold by three loops, one of which, the 3-4 loop (3L4), undergoes substrate-sensitive conformational change. Proteolytic cleavage of the 3L4 was found to abolish transport activity indicating an essential function for this loop in the transport mechanism. Here, we demonstrate that despite the presence of fully cleaved 3L4, Glt(Ph) is still able to sample conformations relevant for transport. Optimized reconstitution conditions reveal that fully cleaved Glt(Ph) retains some transport activity. Analysis of the kinetics and temperature dependence of transport accompanied by direct measurements of substrate binding reveal that this decreased transport activity is not due to alteration of the substrate binding characteristics but is caused by the significantly reduced turnover rate. By measuring solute counterflow activity and cross-link formation rates, we demonstrate that cleaving 3L4 severely and specifically compromises one or more steps contributing to the movement of the substrate-loaded transport domain between the outward- and inward-facing conformational states, sparing the equivalent step(s) during the movement of the empty transport domain. These results reveal a hitherto unknown role for the 3L4 in modulating an essential step in the transport process. PMID:24155238

  8. Supernova explosion mechanism taking into account large-scale convection and neutrino transport

    Science.gov (United States)

    Aksenov, A. G.; Chechetkin, V. M.

    2014-07-01

    Two types of supernovae are considered: thermonuclear supernovae, whose explosions are due to thermonuclear energy, and core-collapse supernovae, whose explosions are due to the gravitational energy of collapsing stars released in the form of neutrinos. Numerical models of supernovae are discussed. Themain problem in devising supernova explosion mechanisms is producing the energy required to disperse the envelope. In theoretical models, it is necessary to solve multi-dimensional problems involving complex physics (3D gas dynamics, neutrino transport, large-scale convective instability, and other important physical processes). In recent years, the development of large-scale convection during supernova explosions has been reconsidered. Self-consistent problems problems in three-dimensional, gas-dynamical instability have been considered. Two-dimensional gas-dynamical calculations taking into account neutrino absorption in the envelope have been performed. The spherically symmetric collapse and neutrino transport were calculated including all reactions, leading to a new understanding of possible paths for the development of supernova theory. The main emphasis is placed on the neutrino transport and the basis for promising multidimensional models taking into account large-scale convective instability.

  9. Enrichment behavior and transport mechanism of soil-bound PAHs during rainfall-runoff events

    International Nuclear Information System (INIS)

    Polycyclic Aromatic Hydrocarbons (PAHs) transported by surface runoff result in nonpoint source pollution and jeopardize aquatic ecosystems. The transport mechanism of PAHs during rainfall-runoff events has been rarely studied regarding pervious areas. An experimental system was setup to simulate the runoff pollution process on PAHs-contaminated soil. The enrichment behavior of soil-bound PAHs was investigated. The results show that soil organic matters (SOM), rather than clay particles, seem to be the main carrier of PAHs. The enrichment is highly conditioned on runoff and erosion processes, and its magnitude varies among PAH compounds. It is not feasible to build a simple and universal relationship between enrichment ratio and sediment discharge following the traditional enrichment theory. To estimate the flux of PAHs from pervious areas, soil erosion process has to be clearly understood, and both organic carbon content and composition of SOM should be factored into the calculation. - Highlights: ► Significant enrichment of particle-bound PAHs during rainfall-runoff events. ► Organic matters as the direct carrier of PAHs in runoff from contaminated soil. ► The traditional enrichment theory is not fully valid for PAHs. - The traditional enrichment theory is not fully valid for PAHs, and soil organic matters have a significant impact on the transport of PAHs during rainfall-runoff events.

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

    Science.gov (United States)

    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 was significantly lower (by 50%) than of dry coals, no hysteresis was observed between sorption and desorption on dry and moisture-equilibrated samples and the sorption isotherms recorded for different particle sizes were essentially identical. The CH4 uptake rates were lower by a factor of two for moist coals than for dry coals. Busch, A., Gensterblum, Y., Krooss, B.M. and Siemons, N., 2006. Investigation of high-pressure selective adsorption/desorption behaviour of CO2 and CH4 on coals: An experimental study. International Journal of Coal Geology, 66(1-2): 53-68. Harpalani, S. and McPherson, M.J., 1985. Effect of stress on permeability of coal. Quarterly Review of methane from coal seams technology, 3(2): 23-29. Seidle, J.P., Jeansonne, M.W. and Erickson, D.J., 1992. Application of Matchstick Geometry to Stress-Dependent Permeability in Coals, SPE Rocky Mountain Regional Meeting, Casper, Wyoming.

  11. Intracellular transport driven by cytoskeletal motors: General mechanisms and defects

    Science.gov (United States)

    Appert-Rolland, C.; Ebbinghaus, M.; Santen, L.

    2015-09-01

    Cells are the elementary units of living organisms, which are able to carry out many vital functions. These functions rely on active processes on a microscopic scale. Therefore, they are strongly out-of-equilibrium systems, which are driven by continuous energy supply. The tasks that have to be performed in order to maintain the cell alive require transportation of various ingredients, some being small, others being large. Intracellular transport processes are able to induce concentration gradients and to carry objects to specific targets. These processes cannot be carried out only by diffusion, as cells may be crowded, and quite elongated on molecular scales. Therefore active transport has to be organized. The cytoskeleton, which is composed of three types of filaments (microtubules, actin and intermediate filaments), determines the shape of the cell, and plays a role in cell motion. It also serves as a road network for a special kind of vehicles, namely the cytoskeletal motors. These molecules can attach to a cytoskeletal filament, perform directed motion, possibly carrying along some cargo, and then detach. It is a central issue to understand how intracellular transport driven by molecular motors is regulated. The interest for this type of question was enhanced when it was discovered that intracellular transport breakdown is one of the signatures of some neuronal diseases like the Alzheimer. We give a survey of the current knowledge on microtubule based intracellular transport. Our review includes on the one hand an overview of biological facts, obtained from experiments, and on the other hand a presentation of some modeling attempts based on cellular automata. We present some background knowledge on the original and variants of the TASEP (Totally Asymmetric Simple Exclusion Process), before turning to more application oriented models. After addressing microtubule based transport in general, with a focus on in vitro experiments, and on cooperative effects in the transportation of large cargos by multiple motors, we concentrate on axonal transport, because of its relevance for neuronal diseases. Some important characteristics of axonal transport is that it takes place in a confined environment; besides several types of motors are involved, that move in opposite directions. It is a challenge to understand how this bidirectional transport is organized. We review several features that could contribute to the efficiency of bidirectional transport in the axon, including in particular the role of motor-motor interactions and of the dynamics of the underlying microtubule network. Finally, we also discuss some open questions that may be relevant for future research in this field.

  12. Cross-field transport in the SOL: Its relationship to main chamber and divertor neutral control in Alcator C-Mod

    International Nuclear Information System (INIS)

    The sources of neutrals at the outer midplane of the plasma are discussed. We find that both the flux of neutrals escaping the divertor through leaks and ion recycling at main chamber surfaces appear to contribute. The ion flux to the walls is larger than the flux entering the divertor and comparable to recycling at the divertor plate. The cause of these high wall ion fluxes is an enhancement of cross-field particle transport which gives rise to substantial convective heat transport at higher densities. We have further explored main chamber recycling and impurity transport utilizing a novel divertor 'bypass', which connects the outer divertor plenum to the main chamber. We find that leakage of neutrals (fuel and recycling impurities) from the divertor appears to be determined primarily by the conductance through the divertor structure, thus indicating that tight baffling would be desirable in a reactor for fuel and helium ash compression. (author)

  13. Proposal for the Award of a Contract for the Management and Operation of the Main Mechanical Workshop at CERN

    CERN Document Server

    2003-01-01

    This document concerns the award of a contract for the management and operation of the main mechanical workshop at CERN. Following a market survey carried out among 55 firms in thirteen Member States, a call for tenders (IT-3116/EST) was sent on 11 October 2002 to two firms and four consortia in seven Member States. By the closing date, CERN had received three tenders from three consortia in six Member States. The Finance Committee is invited to agree to the negotiation of a contract with the consortium CEGELEC (FR) - CEGELEC (NL) - CEGELEC (CH) - CLEMESSY (FR) - CLEMESSY (CH), the lowest bidder, for the management and operation of the main mechanical workshop, for an initial period of three years from 1 October 2003 and for a total amount not exceeding 9 680 000 Swiss francs, subject to revision for inflation from 1 October 2004. The contract will include options for two further one-year extensions beyond the initial three-year period. The consortium has indicated the following distribution by country of the...

  14. Catch bond mechanism in Dynein motor driven collective transport

    CERN Document Server

    Nair, Anil; Mitra, Mithun K; Muhuri, Sudipto; Chaudhuri, Abhishek

    2016-01-01

    Recent experiments have demonstrated that dynein motor exhibits catch bonding behaviour, in which the unbinding rate of a single dynein decreases with increasing force, for a certain range of force. Motivated by these experiments, we propose a model for catch bonding in dynein using a threshold force bond deformation (TFBD) model wherein catch bonding sets in beyond a critical applied load force. We study the effect of catch bonding on unidirectional transport properties of cellular cargo carried by multiple dynein motors within the framework of this model. We find catch bonding can result in dramatic changes in the transport properties, which are in sharp contrast to kinesin driven unidirectional transport, where catch bonding is absent. We predict that, under certain conditions, the average velocity of the cellular cargo can actually increase as applied load is increased. We characterize the transport properties in terms of a velocity profile phase plot in the parameter space of the catch bond strength and ...

  15. Origin of traps and charge transport mechanism in hafnia

    International Nuclear Information System (INIS)

    In this study, we demonstrated experimentally and theoretically that oxygen vacancies are responsible for the charge transport in HfO2. Basing on the model of phonon-assisted tunneling between traps, and assuming that the electron traps are oxygen vacancies, good quantitative agreement between the experimental and theoretical data of current-voltage characteristics was achieved. The thermal trap energy of 1.25 eV in HfO2 was determined based on the charge transport experiments

  16. FEATURES FOR TRANSPORT AND AIR MECHANICAL SYSTEMS OF DANGEROUS GOODS

    Directory of Open Access Journals (Sweden)

    Eugen Dumitru BUSA

    2012-05-01

    Full Text Available Transport of dangerous goods are regulated activities, they take place under the direction and control of the authorities and specialized bodies in an institutional framework determined by national and international law. Of economic, transport infrastructure is the crucial element without which both production and trade would become meaningless, it is an essential element of a civilization, is also a necessary accessory of other economic activities.

  17. Origin of traps and charge transport mechanism in hafnia

    OpenAIRE

    Islamov, D. R.; Gritsenko, V. A.; Cheng, C.H.; Chin, A.

    2014-01-01

    In this study, we demonstrated experimentally and theoretically that oxygen vacancies are responsible for the charge transport in HfO$_2$. Basing on the model of phonon-assisted tunneling between traps, and assuming that the electron traps are oxygen vacancies, good quantitative agreement between the experimental and theoretical data of current-voltage characteristics were achieved. The thermal trap energy of 1.25 eV in HfO$_2$ was determined based on the charge transport experiments.

  18. Intracellular transport driven by cytoskeletal motors: General mechanisms and defects

    CERN Document Server

    Appert-Rolland, Cecile; Santen, Ludger

    2015-01-01

    Cells are strongly out-of-equilibrium systems driven by continuous energy supply. They carry out many vital functions requiring active transport of various ingredients and organelles, some being small, others being large. The cytoskeleton, composed of three types of filaments, determines the shape of the cell and plays a role in cell motion. It also serves as a road network for the so-called cytoskeletal motors. These molecules can attach to a cytoskeletal filament, perform directed motion, possibly carrying along some cargo, and then detach. It is a central issue to understand how intracellular transport driven by molecular motors is regulated, in particular because its breakdown is one of the signatures of some neuronal diseases like the Alzheimer. We give a survey of the current knowledge on microtubule based intracellular transport. We first review some biological facts obtained from experiments, and present some modeling attempts based on cellular automata. We start with background knowledge on the origi...

  19. Structural Insights into the Transport Mechanism of the Human Sodium-dependent Lysophosphatidylcholine Transporter MFSD2A.

    Science.gov (United States)

    Quek, Debra Q Y; Nguyen, Long N; Fan, Hao; Silver, David L

    2016-04-29

    Major facilitator superfamily domain containing 2A (MFSD2A) was recently characterized as a sodium-dependent lysophosphatidylcholine transporter expressed at the blood-brain barrier endothelium. It is the primary route for importation of docosohexaenoic acid and other long-chain fatty acids into fetal and adult brain and is essential for mouse and human brain growth and function. Remarkably, MFSD2A is the first identified major facilitator superfamily member that uniquely transports lipids, implying that MFSD2A harbors unique structural features and transport mechanism. Here, we present three three-dimensional structural models of human MFSD2A derived by homology modeling using MelB- and LacY-based crystal structures and refined by biochemical analysis. All models revealed 12 transmembrane helices and connecting loops and represented the partially outward-open, outward-partially occluded, and inward-open states of the transport cycle. In addition to a conserved sodium-binding site, three unique structural features were identified as follows: a phosphate headgroup binding site, a hydrophobic cleft to accommodate a hydrophobic hydrocarbon tail, and three sets of ionic locks that stabilize the outward-open conformation. Ligand docking studies and biochemical assays identified Lys-436 as a key residue for transport. It is seen forming a salt bridge with the negative charge on the phosphate headgroup. Importantly, MFSD2A transported structurally related acylcarnitines but not a lysolipid without a negative charge, demonstrating the necessity of a negatively charged headgroup interaction with Lys-436 for transport. These findings support a novel transport mechanism by which lysophosphatidylcholines are "flipped" within the transporter cavity by pivoting about Lys-436 leading to net transport from the outer to the inner leaflet of the plasma membrane. PMID:26945070

  20. Origin of traps and charge transport mechanism in hafnia

    Energy Technology Data Exchange (ETDEWEB)

    Islamov, D. R., E-mail: damir@isp.nsc.ru; Gritsenko, V. A., E-mail: grits@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Cheng, C. H. [Department of Mechatronic Technology, National Taiwan Normal University, Taipei 106, Taiwan (China); Chin, A., E-mail: albert-achin@hotmail.com [National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2014-12-01

    In this study, we demonstrated experimentally and theoretically that oxygen vacancies are responsible for the charge transport in HfO{sub 2}. Basing on the model of phonon-assisted tunneling between traps, and assuming that the electron traps are oxygen vacancies, good quantitative agreement between the experimental and theoretical data of current-voltage characteristics was achieved. The thermal trap energy of 1.25 eV in HfO{sub 2} was determined based on the charge transport experiments.

  1. Price Analysis of Railway Freight Transport under Marketing Mechanism

    Science.gov (United States)

    Shi, Ying; Fang, Xiaoping; Chen, Zhiya

    Regarding the problems in the reform of the railway tariff system and the pricing of the transport, by means of assaying the influence of the price elasticity on the artifice used for price, this article proposed multiple regressive model which analyzed price elasticity quantitatively. This model conclude multi-factors which influences on the price elasticity, such as the averagely railway freight charge, the averagely freight haulage of proximate supersede transportation mode, the GDP per capita in the point of origin, and a series of dummy variable which can reflect the features of some productive and consume demesne. It can calculate the price elasticity of different classes in different domains, and predict the freight traffic volume on different rate levels. It can calculate confidence-level, and evaluate the relevance of each parameter to get rid of irrelevant or little relevant variables. It supplied a good theoretical basis for directing the pricing of transport enterprises in market economic conditions, which is suitable for railway freight, passenger traffic and other transportation manner as well. SPSS (Statistical Package for the Social Science) software was used to calculate and analysis the example. This article realized the calculation by HYFX system(Ministry of Railways fund).

  2. A multiclass vehicular dynamic traffic flow model for main roads and dedicated lanes/roads of multimodal transport network

    International Nuclear Information System (INIS)

    We present in this paper a model of vehicular traffic flow for a multimodal transportation road network. We introduce the notion of class of vehicles to refer to vehicles of different transport modes. Our model describes the traffic on highways (which may contain several lanes) and network transit for pubic transportation. The model is drafted with Eulerian and Lagrangian coordinates and uses a Logit model to describe the traffic assignment of our multiclass vehicular flow description on shared roads. The paper also discusses traffic streams on dedicated lanes for specific class of vehicles with event-based traffic laws. An Euler-Lagrangian-remap scheme is introduced to numerically approximate the model’s flow equations

  3. A multiclass vehicular dynamic traffic flow model for main roads and dedicated lanes/roads of multimodal transport network

    Energy Technology Data Exchange (ETDEWEB)

    Sossoe, K.S., E-mail: kwami.sossoe@irt-systemx.fr [TECHNOLOGICAL RESEARCH INSTITUTE SYSTEMX (France); Lebacque, J-P., E-mail: jean-patrick.lebacque@ifsttar.fr [UPE/IFSTTAR-COSYS-GRETTIA (France)

    2015-03-10

    We present in this paper a model of vehicular traffic flow for a multimodal transportation road network. We introduce the notion of class of vehicles to refer to vehicles of different transport modes. Our model describes the traffic on highways (which may contain several lanes) and network transit for pubic transportation. The model is drafted with Eulerian and Lagrangian coordinates and uses a Logit model to describe the traffic assignment of our multiclass vehicular flow description on shared roads. The paper also discusses traffic streams on dedicated lanes for specific class of vehicles with event-based traffic laws. An Euler-Lagrangian-remap scheme is introduced to numerically approximate the model’s flow equations.

  4. Na+-stimulated phosphate uptake system in Synechocystis sp. PCC 6803 with Pst1 as a main transporter

    OpenAIRE

    Burut-Archanai, Surachet; Eaton-Rye, Julian J.; Incharoensakdi, Aran

    2011-01-01

    Background Most living cells uptake phosphate, an indispensable nutrient for growth from their natural environment. In Synechocystis sp. PCC 6803, the cells lack phosphate-inorganic transport (Pit) system but contain two phosphate-specific transport (Pst) systems, Pst1 and Pst2. We investigated the kinetics of Pi uptake of these two Pst systems by constructing the two mutants, ΔPst1 and ΔPst2, and comparing their kinetic properties with those of the wild-type cells under both Pi-sufficient an...

  5. MANGANESE AS ESSENTIAL AND TOXIC ELEMENT FOR PLANTS: TRANSPORT, ACCUMULATION AND RESISTANCE MECHANISMS

    Directory of Open Access Journals (Sweden)

    R Millaleo

    2010-01-01

    Full Text Available Manganese is an essential element for plants, intervening in several metabolic processes, mainly in photosynthesis and as an enzyme antioxidant-cofactor. Nevertheless, an excess of this micronutrient is toxic for plants. Mn phytotoxicity is manifested in a reduction of biomass and photosynthesis, and biochemical disorders such as oxidative stress. Some studies on Mn toxicity and Mn translocation from soil to plant cells in Mn2+ form have demonstrated their importance under low pH and redox potential conditions in the soil. When Mn is inside the cells, mechanisms that can tolerate this toxicity are also observed, being important the compartmentalization of this metal in different organdes of shoot and leaf plant cells. A key role of antioxidative systems in plants in relation to high Mn amounts has also been reported as a defense mechanism. The purpose of this review is to show the role of Mn as an essential micronutrient and as a toxic element to higher plants as well as to their transport and tolerance mechanisms. The forms and dynamics of this element in soils and the importance of the acidity for this dynamic and availability for plants are also given.

  6. Current transport mechanisms in lattice-matched Pt/Au-InAlN/GaN Schottky diodes

    International Nuclear Information System (INIS)

    Lattice-matched Pt/Au-In0.17Al0.83N/GaN hetreojunction Schottky diodes with circular planar structure have been fabricated and investigated by temperature dependent electrical measurements. The forward and reverse current transport mechanisms are analyzed by fitting the experimental current-voltage characteristics of the devices with various models. The results show that (1) the forward-low-bias current is mainly due to the multiple trap-assisted tunneling, while the forward-high-bias current is governed by the thermionic emission mechanism with a significant series resistance effect; (2) the reverse leakage current under low electric fields (<6 MV/cm) is mainly carried by the Frenkel-Poole emission electrons, while at higher fields the Fowler-Nordheim tunneling mechanism dominates due to the formation of a triangular barrier

  7. Current transport mechanisms in lattice-matched Pt/Au-InAlN/GaN Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jian; Yan, Dawei, E-mail: daweiyan@jiangnan.edu.cn; Yang, Guofeng; Wang, Fuxue; Xiao, Shaoqing; Gu, Xiaofeng [Key Laboratory of Advanced Process Control for Light Industry (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122 (China)

    2015-04-21

    Lattice-matched Pt/Au-In{sub 0.17}Al{sub 0.83}N/GaN hetreojunction Schottky diodes with circular planar structure have been fabricated and investigated by temperature dependent electrical measurements. The forward and reverse current transport mechanisms are analyzed by fitting the experimental current-voltage characteristics of the devices with various models. The results show that (1) the forward-low-bias current is mainly due to the multiple trap-assisted tunneling, while the forward-high-bias current is governed by the thermionic emission mechanism with a significant series resistance effect; (2) the reverse leakage current under low electric fields (<6 MV/cm) is mainly carried by the Frenkel-Poole emission electrons, while at higher fields the Fowler-Nordheim tunneling mechanism dominates due to the formation of a triangular barrier.

  8. Mechanism of Paroxetine (Paxil) Inhibition of the Serotonin Transporter

    Science.gov (United States)

    Davis, Bruce A.; Nagarajan, Anu; Forrest, Lucy R.; Singh, Satinder K.

    2016-01-01

    The serotonin transporter (SERT) is an integral membrane protein that exploits preexisting sodium-, chloride-, and potassium ion gradients to catalyze the thermodynamically unfavorable movement of synaptic serotonin into the presynaptic neuron. SERT has garnered significant clinical attention partly because it is the target of multiple psychoactive agents, including the antidepressant paroxetine (Paxil), the most potent selective serotonin reuptake inhibitor known. However, the binding site and orientation of paroxetine in SERT remain controversial. To provide molecular insight, we constructed SERT homology models based on the Drosophila melanogaster dopamine transporter and docked paroxetine to these models. We tested the predicted binding configurations with a combination of radioligand binding and flux assays on wild-type and mutant SERTs. Our data suggest that the orientation of paroxetine, specifically its fluorophenyl ring, in SERT’s substrate binding site directly depends on this pocket’s charge distribution, and thereby provide an avenue toward understanding and enhancing high-affinity antidepressant activity. PMID:27032980

  9. Mechanism of Paroxetine (Paxil) Inhibition of the Serotonin Transporter.

    Science.gov (United States)

    Davis, Bruce A; Nagarajan, Anu; Forrest, Lucy R; Singh, Satinder K

    2016-01-01

    The serotonin transporter (SERT) is an integral membrane protein that exploits preexisting sodium-, chloride-, and potassium ion gradients to catalyze the thermodynamically unfavorable movement of synaptic serotonin into the presynaptic neuron. SERT has garnered significant clinical attention partly because it is the target of multiple psychoactive agents, including the antidepressant paroxetine (Paxil), the most potent selective serotonin reuptake inhibitor known. However, the binding site and orientation of paroxetine in SERT remain controversial. To provide molecular insight, we constructed SERT homology models based on the Drosophila melanogaster dopamine transporter and docked paroxetine to these models. We tested the predicted binding configurations with a combination of radioligand binding and flux assays on wild-type and mutant SERTs. Our data suggest that the orientation of paroxetine, specifically its fluorophenyl ring, in SERT's substrate binding site directly depends on this pocket's charge distribution, and thereby provide an avenue toward understanding and enhancing high-affinity antidepressant activity. PMID:27032980

  10. Molecular mechanism of regulation of iron transport across placenta

    OpenAIRE

    Hanif, R.

    2012-01-01

    During the third trimester of pregnancy, iron transport from mother to the foetus against a concentration gradient determines the iron endowment in foetal and neonatal life. Hfe functions as an upstream regulator of liver hepcidin which has been demonstrated to be a negative regulator of intestinal absorption of dietary iron and macrophage efflux of recycled iron. Hepcidin has also been proposed to be a negative regulator of iron efflux from the placenta, however it is not k...

  11. On the mechanism of gas transport in rigid polymer membranes

    OpenAIRE

    Hensema, E.R.; Mulder, M.H.V.; Smolders, C.A.

    1993-01-01

    Conventional polymers are compared as gas separation membrane materials with tailormade polymers. The increased permeability of the latter are due to their higher free volume available for gas transport. The increased free volume is associated with the rigidity polymer backbone. Free volume is obtained by subtracting the occupied volume, calculated using group contributions from the polymer specific volume. Wide Angle X-ray techniques are used to obtain average d-spacings that are interpreted...

  12. Catch bond mechanism in Dynein motor driven collective transport

    OpenAIRE

    Nair, Anil; Chandel, Sameep; Mitra, Mithun K; Muhuri, Sudipto; Chaudhuri, Abhishek

    2016-01-01

    Recent experiments have demonstrated that dynein motor exhibits catch bonding behaviour, in which the unbinding rate of a single dynein decreases with increasing force, for a certain range of force. Motivated by these experiments, we propose a model for catch bonding in dynein using a threshold force bond deformation (TFBD) model wherein catch bonding sets in beyond a critical applied load force. We study the effect of catch bonding on unidirectional transport properties of cellular cargo car...

  13. An ambiguous interface – on the transport mechanism of the ABC transport complex TAP

    OpenAIRE

    Großmann, Nina

    2012-01-01

    The adaptive immune system protects against daily infections and malignant transformation. In this, the translocation of antigenic peptides by the transporter associated with antigen processing (TAP) into the ER lumen is an essential step in the antigen presentation by MHC I molecules. The heterodimeric ATP-binding cassette transporter (ABC) TAP consist of the two halftransporters TAP1 and TAP2. Each monomer contains an N-terminal transmembrane domain (TMD) and a conserved C-terminal nucleoti...

  14. New Approaches to Solute Transport Measurement in Mechanically Loaded Articular Cartilage

    Science.gov (United States)

    Quinn, Thomas M.; Dunlop, Amy E.; Evans, Robin C.

    Diffusive and convective transport of bioactive solutes within the extracellular matrix of articular cartilage plays an important role in the regulation of tissue physiology and the cell biological response to mechanical compression. With a view toward identifying means to employ mechanical control of solute transport for the optimization of in vitro methods of cartilage tissue engineering, we have developed techniques for real-time observation and quantification of solute transport within statically compressed cartilage explants in the presence of interstitial fluid flows and matrix inhomogeneities, and also within dynamically compressed cartilage explants. Initial results confirm the potential usefulness of the new methods, and suggest roles for transport phenomena in regulation of the cartilage biological response to static and dynamic compression. Further characterization of solute transport using these methods may therefore guide the optimization of in vitro mechanical loading protocols used in cartilage tissue engineering.

  15. Lipid transport function is the main target of oral oleoylethanolamide to reduce adiposity in high-fat-fed mice

    OpenAIRE

    Thabuis, Clémentine; Destaillats, Frédéric; Lambert, Didier; Muccioli, Giulio; Maillot, Matthieu; Harach, Touafiq; Tissot-Favre, Delphine; Martin, Jean-Charles

    2011-01-01

    We evaluated the biological basis of reduced fat gain by oleoylethanolamide (OEA) in high-fat-fed mice and sought to determine how degradation of OEA affected its efficiency by comparing its effects to those of KDS-5104, a nonhydrolyzable lipid OEA analog. Mice were given OEA or KDS-5104 by the oral route (100 mg/kg body weight). Sixty-eight variables per mouse, describing six biological processes (lipid transport, lipogenesis, energy intake, energy expenditure, endocannabinoid signaling, and...

  16. Thermo-mechanical simulation of austenitic steel welding process with respect to main vessel roof slab shell joint

    International Nuclear Information System (INIS)

    Welding process involves high heat fluxes which give rise to high temperature gradient in vicinity of the weld region. Presence of various mechanical constraints to minimize the distortion results in high residual stresses in the weld region. Weld joint between main vessel and roof slab of Sodium cooled Fast Reactors (SFRs) results in distortion and residual stress; hence it is critical from functionality point of view. The welding of main vessel (13 m diameter) and roof slab of 25 mm thickness involves multi-pass weld. In the present work an attempt has been made to simulate the 3D multipass welding procedure using the element birth technique for the filler material addition. The accurate estimation of the residual stress distribution is required as one of the basic input for the study of crack propagation behavior in the critical weld zone. Also to minimize the global distortion of the shell prior information of the supports and clamping location is essential. The actual welding process involves an asymmetric k type of weld joint with 21 passes on alternating sides to neutralize the distortions produced by one pass by the other alternating pass on the opposite side. The whole vessel will be divided into four quarter circles and the welding will be started simultaneously from all the four points in counter-clockwise direction at same speed. In the view of very high computation time required for the actual simulation of this weld joint, a small mockup exercise has been done to investigate the local residual stress and the forces. (orig.)

  17. Envisaging palladium chemical transport mechanism from fuel kernel pellet to SiC cladding by bromination

    Energy Technology Data Exchange (ETDEWEB)

    Arias, F.J., E-mail: frarias@mit.edu [Nuclear Science and Engineering Department, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2012-07-15

    The SiC cladding corrosion in pellets by direct palladium chemical transport from fuel kernel through gap to SiC cladding by direct bromination is envisaged as feasible mechanism in corrosion of SiC pellets.

  18. Computerized simulation of the mechanical behavior of wood-filled shock absorbers of radioactive materials transport casks

    International Nuclear Information System (INIS)

    In Germany the mechanical component inspection of transport containers for radioactive materials is performed by BAM (Bundesanstalt fuer Materialforschung und -pruefung) under consideration of national and international standards and guidelines. Experimental and calculative (analytical and numerical) techniques combined with material and/or component testing are the basis of assessment concepts according the state of the art. The authors describe the experiences of BAM concerning assessment and description of the mechanical behavior of shock absorbing components, including modeling strategies, material models, drop tests and experiment-calculation comparison. Energy absorbing components are used to reduce the impact forces at the container in case of a transport accident. In Germany wood filled thin-walled constructions are used. The deformation behavior of the wood is a main part of the calculative simulation procedures in comparison with experimental tests.

  19. Mechanism(S) Involved in the Colon-Specific Expression of the Thiamine Pyrophosphate (Tpp) Transporter

    Science.gov (United States)

    Nabokina, Svetlana M.; Ramos, Mel Brendan; Said, Hamid M.

    2016-01-01

    Microbiota of the large intestine synthesizes considerable amount of vitamin B1 (thiamine) in the form of thiamine pyrophosphate (TPP). We have recently demonstrated the existence of an efficient and specific carrier-mediated uptake process for TPP in human colonocytes, identified the TPP transporter (TPPT) involved (product of the SLC44A4 gene), and shown that expression of TPPT along the gastrointestinal (GI) tract is restricted to the colon. Our aim in this study was to determine the molecular basis of the colon-specific expression of TPPT focusing on a possible epigenetic mechanism. Our results showed that the CpG island predicted in the SLC44A4 promoter is non-methylated in the human colonic epithelial NCM460 cells, but is hyper-methylated in the human duodenal epithelial HuTu80 cells (as well as in the human retinal pigment epithelial ARPE19 cells). In the mouse (where TPPT expression in the GI tract is also restricted to the colon), the CpG island predicted in the Slc44a4 promoter is non-methylated in both the jejunum and colon, thus arguing against possible contribution of DNA methylation in the colon-specific expression of TPPT. A role for histone modifications in the tissue-specific pattern of Slc44a4 expression, however, was suggested by the findings that in mouse colon, histone H3 in the 5’-regulatory region of Slc44a4 is tri-methylated at lysine 4 and acetylated at lysine 9, whereas the tri-methylation at lysine 27 modification was negligible. In contrast, in the mouse jejunum, histone H3 is hyper-trimethylated at lysine 27 (repressor mark). Similarly, possible involvement of miRNA(s) in the tissue-specific expression of TPPT was also suggested by the findings that the 3’-UTR of SLC44A4 is targeted by specific miRNAs/RNA binding proteins in non-colonic, but not in colonic, epithelial cells. These studies show, for the first time, epigenetic mechanisms (histone modifications) play a role in determining the tissue-specific pattern of expression of TPPT in the GI tract. PMID:26901654

  20. Angler awareness of aquatic nuisance species and potential transport mechanisms

    Science.gov (United States)

    Gates, K.K.; Guy, C.S.; Zale, A.V.; Horton, T.B.

    2009-01-01

    The role anglers play in transporting aquatic nuisance species (ANS) is important in managing infestations and preventing introductions. The objectives of this study were to: (1) quantify angler movement patterns in southwestern Montana, ANS awareness and equipment cleaning practices; and (2) quantify the amount of soil transported on boots and waders. Mean distance travelled by residents from their home to the survey site was 115 km (??17, 95% CI). Mean distance travelled by non-residents was 1738 km (??74). Fifty-one percent of residents and 49% of non-residents reported occasionally, rarely or never cleaning their boots and waders between uses. Mean weight of soil carried on one boot leg was 8.39 g (??1.50). Movement and equipment cleaning practices of anglers in southwestern Montana suggest that future control of ANS dispersal may require restricting the use of felt-soled wading boots, requiring river-specific wading equipment or providing cleaning stations and requiring their use. ?? 2009 Blackwell Publishing Ltd.

  1. Turbulence elasticityA new mechanism for transport barrier dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Z. B., E-mail: guozhipku@gmail.com [WCI Center for Fusion Theory, NFRI, Daejeon 305-333 (Korea, Republic of); Diamond, P. H. [WCI Center for Fusion Theory, NFRI, Daejeon 305-333 (Korea, Republic of); CMTFO and CASS, University of California, San Diego, California 92093 (United States); Kosuga, Y. [IAS and RIAM, Kyushu University, Kasuga 816-8580 (Japan); Grcan, . D. [LPP, Ecole Polytechnique, CNRS, Palaiseau Cedex 91128 (France)

    2014-09-15

    We present a new, unified model of transport barrier formation in elastic drift wave-zonal flow (DW-ZF) turbulence. A new physical quantitythe delay time (i.e., the mixing time for the DW turbulence)is demonstrated to parameterize each stage of the transport barrier formation. Quantitative predictions for the onset of limit-cycle-oscillation (LCO) among DW and ZF intensities (also denoted as I-mode) and I-mode to high-confinement mode (H-mode) transition are also given. The LCO occurs when the ZF shearing rate (|?v?{sub ZF}{sup ?}|) enters the regime ??{sub k}<|?V?{sub ZF}{sup ?}|?{sub cr}{sup ?1}, where the mean E??B shear flow driven by ion pressure locks the DW-ZF system to the H-mode by reducing the delay time below the threshold value.

  2. Turbulence elasticity—A new mechanism for transport barrier dynamics

    International Nuclear Information System (INIS)

    We present a new, unified model of transport barrier formation in “elastic” drift wave-zonal flow (DW-ZF) turbulence. A new physical quantity—the delay time (i.e., the mixing time for the DW turbulence)—is demonstrated to parameterize each stage of the transport barrier formation. Quantitative predictions for the onset of limit-cycle-oscillation (LCO) among DW and ZF intensities (also denoted as I-mode) and I-mode to high-confinement mode (H-mode) transition are also given. The LCO occurs when the ZF shearing rate (|〈v〉ZF′|) enters the regime ΔωkZF′|cr−1, where Δωk is the local turbulence decorrelation rate and τcr is the threshold delay time. In the basic predator-prey feedback system, τcr is also derived. The I-H transition occurs when |〈V〉E×B′|>τcr−1, where the mean E × B shear flow driven by ion pressure “locks” the DW-ZF system to the H-mode by reducing the delay time below the threshold value

  3. Water transport mechanisms across inorganic membranes in rad waste treatment by electro dialysis

    International Nuclear Information System (INIS)

    The work described in this paper deals with effects and mechanisms of water transport across an inorganic membrane, as related to some studied on the concentration of caesium, strontium, plutonium and other cations of interest to radioactive waste treatment. Several different water transport mechanisms are analysed and assessed as to their individual contribution towards the total transference of water during electro-dialysis using inorganic membranes. Water transfer assisted by proton jump mechanism, water of hydration transferred along with the ions, water related to thermo-osmotic effect, water transferred by concentration gradient and water transferred electrolytically under zeta potential surface charge drive are some of the different mechanism discussed. (author)

  4. The transport mechanism of integrin αvβ3 receptor targeting nanoparticles in Caco-2 cells.

    Science.gov (United States)

    Xu, Yining; Xu, Juan; Shan, Wei; Liu, Min; Cui, Yi; Li, Lian; Liu, Chong; Huang, Yuan

    2016-03-16

    As for the existence of epithelium barrier, accelerating the transport remains huge challenges for orally delivered protein and peptide drugs into blood circulation. Modifying nanopaticles (NPs) with targeting peptides can enhance the intestinal absorption of loaded macromolecular drugs. However, the transport process, which mainly means how the NPs pass through the apical membrane and the basolateral side and then enter into blood circulation, is needed comprehensive investigation. In this study, we systemically studied the transport mechanisms in Caco-2 cell model of trimethyl chitosan based NPs (TMC NPs) before and after modification of FQS, an integrin αvβ3 receptor targeting peptide. Our results showed FQS peptide mediated multiple endocytosis pathways and could activate integrin αvβ3 receptor by interacting with FAK and Src-family kinases to induce receptor-mediated endocytosis of the NPs. Then, both endocytosed NPs could transport from early endosome to lysososmes via late endosomes/lysosome pathway, as well as to recycling endosomes and Golgi apparatus through early endosome/recycling endosomes and Golgi apparatus/recycling endosomes/plasma membrane pathways, respectively. After FQS peptide modification, the endocytosis subpathways of NPs have been changed, and more pathways are involved in exocytosis process for FQS-modified NPs compared with non-modified NPs. Our study indicated the ligand modification could enhance the uptake and transport by altering some pathways in whole transport process of NPs. PMID:26784984

  5. Understanding the removal mechanisms of PPCPs and the influence of main technological parameters in anaerobic UASB and aerobic CAS reactors

    International Nuclear Information System (INIS)

    Highlights: • Removals of 16 PPCPs under aerobic and anaerobic conditions were quantified. • Operation conditions (HRT, vup, biomass activity and conformation) influenced removal. • Highest removals associated to aerobic biodegradation. • Sorption was only relevant for lipophilic compounds in the UASB reactor. - Abstract: The removal of 16 Pharmaceutical and Personal Care Products (PPCPs) were studied in a conventional activated sludge (CAS) unit and an upflow anaerobic sludge blanket (UASB) reactor. Special attention was paid to each biomass conformation and activity as well as to operational conditions. Biodegradation was the main PPCP removal mechanism, being higher removals achieved under aerobic conditions, except in the case of sulfamethoxazole and trimetrophim. Under anaerobic conditions, PPCP biodegradation was correlated with the methanogenic rate, while in the aerobic reactor a relationship with nitrification was found. Sorption onto sludge was influenced by biomass conformation, being only significant for musk fragrances in the UASB reactor, in which an increase of the upward velocity and hydraulic retention time improved this removal. Additionally, PPCP sorption increased with time in the UASB reactor, due to the granular biomass structure which suggests the existence of intra-molecular diffusion

  6. Understanding the removal mechanisms of PPCPs and the influence of main technological parameters in anaerobic UASB and aerobic CAS reactors

    Energy Technology Data Exchange (ETDEWEB)

    Alvarino, T., E-mail: teresa.alvarino@usc.es; Suarez, S., E-mail: Sonia.suarez@usc.es; Lema, J.M., E-mail: juan.lema@usc.es; Omil, F., E-mail: francisco.omil@usc.es

    2014-08-15

    Highlights: Removals of 16 PPCPs under aerobic and anaerobic conditions were quantified. Operation conditions (HRT, v{sub up}, biomass activity and conformation) influenced removal. Highest removals associated to aerobic biodegradation. Sorption was only relevant for lipophilic compounds in the UASB reactor. - Abstract: The removal of 16 Pharmaceutical and Personal Care Products (PPCPs) were studied in a conventional activated sludge (CAS) unit and an upflow anaerobic sludge blanket (UASB) reactor. Special attention was paid to each biomass conformation and activity as well as to operational conditions. Biodegradation was the main PPCP removal mechanism, being higher removals achieved under aerobic conditions, except in the case of sulfamethoxazole and trimetrophim. Under anaerobic conditions, PPCP biodegradation was correlated with the methanogenic rate, while in the aerobic reactor a relationship with nitrification was found. Sorption onto sludge was influenced by biomass conformation, being only significant for musk fragrances in the UASB reactor, in which an increase of the upward velocity and hydraulic retention time improved this removal. Additionally, PPCP sorption increased with time in the UASB reactor, due to the granular biomass structure which suggests the existence of intra-molecular diffusion.

  7. Transport mechanisms in high Tc bismuth-based oxide superconductors

    International Nuclear Information System (INIS)

    We apply our transport theory (I) on high temperature oxide superconductor was presented. Our calculations on bismuth based high temperature oxide superconductors suggest that the polarons may exist. There exists, no bipolarons. The polarons are produced due to free or dangling bonds of oxygen. The Cooper pairs while remaining on a pseudo Fermi surface behave like weak fermions. When the Cooper pairs become free they behave as spinless bosons. The binding energies of Cooper pairs both in a weak fermions system and for spinless bosons are calculated. A kind of semimetallic transition is responsible for high temperature superconductivity and is temperature independent. There is no electron-polaron, coupling for high temperature superconductors. High temperature oxide superconductors before the onset of superconductivity are found to be Mott insulating materials. Our results are in conformity with theory (I). (author)

  8. The proton-coupled amino acid transporter hPAT1 is the main transporter involved in vigabatrin uptake in intestinal Caco-2 cells

    DEFF Research Database (Denmark)

    Nøhr, Martha Kampp; Hansen, Steen Honore'; Brodin, Birger; Holm, René; Nielsen, Carsten Uhd

    2012-01-01

    transporter hPAT1. The aim of the project was to identify if transporters are involved in cellular uptake of vigabatrin in Caco-2 cells. Methods: The uptake rate of vigabatrin was measured in Caco-2 cells at pH 6.0 or 7.4 for 15 min after application of 0.1 – 25.0 mM vigabatrin. The inhibitory effect of...... vigabatrin was saturable at pH 6.0 with a Michaelis constant, Km of 12.7 ± 3.7 mM and a maximal flux, Jmax of 3.7 ± 0.5 nmol•min-1•cm-2. The presences of hPAT1 ligands significantly inhibited the uptake of vigabatrin in Caco-2 cells at pH 6.0, whereas hPAT1 non-ligands did not. Discussion: The saturability...... of the uptake at pH 6.0 indicates involvement of a carrier-mediated process in vigabatrin absorption. The pH-dependency of the vigabatrin uptake suggests that the uptake may be driven by a proton-coupled transporter. The Km-value is comparable to Km- values for other hPAT1 substrates (1-20 mM). The...

  9. Cytoplasmic HIV-1 RNA is mainly transported by diffusion in the presence or absence of Gag protein

    DEFF Research Database (Denmark)

    Chen, Jianbo; Grunwald, David; Sardo, Luca; Galli, Andrea; Plisov, Sergey; Nikolaitchik, Olga A; Chen, De; Lockett, Stephen; Larson, Daniel R; Pathak, Vinay K; Hu, Wei-Shau

    2014-01-01

    Full-length HIV-1 RNA plays a central role in viral replication by serving as the mRNA for essential viral proteins and as the genome packaged into infectious virions. Proper RNA trafficking is required for the functions of RNA and its encoded proteins; however, the mechanism by which HIV-1 RNA i...

  10. Mechanisms of Transport of Copper, Cadmium and Chromium in Soils

    OpenAIRE

    Biggar, J. W.; Tanji, K. K.; Nielsen, D. R.; Miller, R.J.

    1981-01-01

    The copper in the saturation extract of dried Davis sewage sludge was mainly in a complexed form. A Cu2+ specific ion electrode was used to determine the extent of complexation. Absorption experiments showed that the Kd value of 90 cc g-1. Paper electrophoresis was used to define the complexes according to their mobility in an electric field. Six fractions of positive, negative and neutral charge were isolated. The fraction of Cu in the sludge which was water soluble was found to increase sig...

  11. Coupling mechanical forces to electrical signaling: molecular motors and the intracellular transport of ion channels.

    Science.gov (United States)

    Barry, Joshua; Gu, Chen

    2013-04-01

    Proper localization of various ion channels is fundamental to neuronal functions, including postsynaptic potential plasticity, dendritic integration, action potential initiation and propagation, and neurotransmitter release. Microtubule-based forward transport mediated by kinesin motors plays a key role in placing ion channel proteins to correct subcellular compartments. PDZ- and coiled-coil-domain proteins function as adaptor proteins linking ionotropic glutamate and GABA receptors to various kinesin motors, respectively. Recent studies show that several voltage-gated ion channel/transporter proteins directly bind to kinesins during forward transport. Three major regulatory mechanisms underlying intracellular transport of ion channels are also revealed. These studies contribute to understanding how mechanical forces are coupled to electrical signaling and illuminating pathogenic mechanisms in neurodegenerative diseases. PMID:22910031

  12. Grotthuss mechanisms: from proton transport in proton wires to bioprotonic devices

    Science.gov (United States)

    Miyake, Takeo; Rolandi, Marco

    2016-01-01

    In 1804, Theodore von Grotthuss proposed a mechanism for proton (H+) transport between water molecules that involves the exchange of a covalent bond between H and O with a hydrogen bond. This mechanism also supports the transport of OH? as a proton hole and is essential in explaining proton transport in intramembrane proton channels. Inspired by the Grotthuss mechanism and its similarity to electron and hole transport in semiconductors, we have developed semiconductor type devices that are able to control and monitor a current of H+ as well as OH? in hydrated biopolymers. In this topical review, we revisit these devices that include protonic diodes, complementary, transistors, memories and transducers as well as a phenomenological description of their behavior that is analogous to electronic semiconductor devices.

  13. Grotthuss mechanisms: from proton transport in proton wires to bioprotonic devices.

    Science.gov (United States)

    Miyake, Takeo; Rolandi, Marco

    2016-01-20

    In 1804, Theodore von Grotthuss proposed a mechanism for proton (H(+)) transport between water molecules that involves the exchange of a covalent bond between H and O with a hydrogen bond. This mechanism also supports the transport of OH(-) as a proton hole and is essential in explaining proton transport in intramembrane proton channels. Inspired by the Grotthuss mechanism and its similarity to electron and hole transport in semiconductors, we have developed semiconductor type devices that are able to control and monitor a current of H(+) as well as OH(-) in hydrated biopolymers. In this topical review, we revisit these devices that include protonic diodes, complementary, transistors, memories and transducers as well as a phenomenological description of their behavior that is analogous to electronic semiconductor devices. PMID:26657711

  14. Mechanism of unassisted ion transport across membrane bilayers

    Science.gov (United States)

    Wilson, M. A.; Pohorille, A.

    1996-01-01

    To establish how charged species move from water to the nonpolar membrane interior and to determine the energetic and structural effects accompanying this process, we performed molecular dynamics simulations of the transport of Na+ and Cl- across a lipid bilayer located between two water lamellae. The total length of molecular dynamics trajectories generated for each ion was 10 ns. Our simulations demonstrate that permeation of ions into the membrane is accompanied by the formation of deep, asymmetric thinning defects in the bilayer, whereby polar lipid head groups and water penetrate the nonpolar membrane interior. Once the ion crosses the midplane of the bilayer the deformation "switches sides"; the initial defect slowly relaxes, and a defect forms in the outgoing side of the bilayer. As a result, the ion remains well solvated during the process; the total number of oxygen atoms from water and lipid head groups in the first solvation shell remains constant. A similar membrane deformation is formed when the ion is instantaneously inserted into the interior of the bilayer. The formation of defects considerably lowers the free energy barrier to transfer of the ion across the bilayer and, consequently, increases the permeabilities of the membrane to ions, compared to the rigid, planar structure, by approximately 14 orders of magnitude. Our results have implications for drug delivery using liposomes and peptide insertion into membranes.

  15. Dissolved load transport in the Ebro River Basin (Spain): Impact of main lithologies and role of tributaries

    Science.gov (United States)

    Petelet-Giraud, E.; Negrel, P. J.

    2012-12-01

    This study aims to evaluate, over more than 20 years, the export fluxes for dissolved loads at the Ebro River catchment scale. Data are compiled from the of the Confederacion Hidrografica del Ebro (CHE) databank. The spatial and temporal distribution of daily discharges, physico-chemical parameters and chemical data covering the last two decades (1981-2003) were investigated on five monitoring stations along the Ebro River (Mendavia, Castejon, Zaragoza, Sastago and Tortosa), as well as six stations at the outlet of the main tributaries (Arga, Aragon, Gallego, Jalon, Cinca and Segre). The dissolved load of the rivers at the Ebro Basin scale was characterized through the Electrical Conductivity (EC), total dissolved solids (TDS) and the major elements chemical data. The surface water can be classified into three main categories, a clear dominance of Ca-SO4 water type, a Ca-HCO3 type mainly encountered in the upper part of the basin and some data presenting a Na-Cl water type. The TDS values are highly variable, both in time and in space, in the range 390-1360 mg/L. The dissolved exportations to the Mediterranean Sea and the relative contribution of the different tributaries were calculated. The Ebro basin in its upper part (upstream Mendavia) contributes around 22.4% of the total exported flux near the outlet (Tortosa) over the studied period. The tributaries that mainly contribute to the total exported dissolved load are the Cinca and Segre (19% and 17% respectively). The Aragon, Gallego and Jalon contributions are very low, often less than 5% of the total exported flux. The specific TDS flux at the outlet of the Ebro is 70 +/- 23 t/km2/year and 108 +/- 24 t/km2/year upstream in Mendavia while the highest chemical erosion rate was calculated for the Arga with 251 +/- 55 t/km2/year. The dissolved export fluxes represent the major export from the Ebro basin, and the respective contribution of carbonate and evaporite (gypsum) with respect to the TDS was then calculated using the major element concentrations and discharge data. In the upper part of the Ebro Basin, carbonate weathering is dominant compared to gypsum weathering while downstream the dissolved exportations are dominated by gypsum weathering. For the tributaries, most of them are dominated by evaporite weathering. The exportation rates at the outlet of the watershed shows dissolved exportation derived from gypsum weathering, that are about 1.5 times that derived from carbonate weathering

  16. Main Achievements 2003-2004 - Experimental Nuclear Physics - Mechanisms of nuclear reactions - Thermal multifragmentation and liquid-fog transition

    International Nuclear Information System (INIS)

    The main decay mode of very excited nuclei is a copious emission of intermediate mass fragments (IMF), which are heavier than ?-particles but lighter than fission fragments. The FASA project is concentrated on the investigation of thermal multifragmentation induced in heavy targets by relativistic light ions. The 4?-setup is installed at the external beam of Nuclotron. It was proved that thermal multifragmentation should be considered as a spinodal decomposition, which is the liquid-fog phase transition. Measurements of critical temperature for the liquid-gas phase transition were refined. This temperature was found to be (17 2) MeV, which is significantly larger than the temperature of the fragmenting system (5-6 MeV). This is a very important observation in favour of the mechanism of spinodal disintegration. The space characteristics for the target multifragmentation in p(8.1 GeV) + Au collisions were also determined experimentally. The inclusive experimental data on the fragment charge distribution, Y(Z), and kinetic energy spectra were analyzed within the framework of the statistical multifragmentation model. It is found from the shape of Y(Z) that the partition of hot nuclei is specified after expansion of the target spectator to a volume equal to Vt= (2.9 0.2) V0, with V0 being the volume at normal density. However, the freeze-out volume is found from the energy spectra to be Vf = (11 3) V0. The first volume, Vt, corresponds to the configuration of the system at the top of the energy barrier for fragmentation, when charge distribution is specified. The other volume, Vf, corresponds to the multi-scission point in terms of ordinary fission

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-01-01

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

  18. Mechanism of arsenate inhibition of the glucose active transport system in Neurospora crassa

    International Nuclear Information System (INIS)

    The mechanism of arsenate inhibition of the glucose active transport system in wild-type cells of Neurospora crassa has been examined. Arsenate treatment results in approximately 65% inhibition of the glucose active transport system with only a small depression of cellular ATP levels. The transport system is not inhibited in cells treated with sodium arsenate in the presence of sodium azide. The transport inhibition is suppressed when orthophosphate is present during arsenate treatment, but is not reversed by orthophosphate when added after the arsenate treatment. The transport inhibition is completely reversed by treatment of the cells with mercaptoethanol. Gel chromatography of sonicates of intact cells which had been treated with [74As]arsenate reveals three radioactive peaks, one with the elution volume of arsenate, one with the elution volume of arsenite, and in high molecular-weight radioactive fraction. Treatment of the high molecular-weight radioactive fraction with mercaptoethanol results in the production of radioactive arsenite. In view of these findings, it is proposed that arsenate inhibition of the glucose active transport system in Neurospora involves transport of arsenate into the cells, probably via the orthophosphate transport system, reduction of the transported arsenate to arsenite, and interaction of arsenite with some component of the glucose active transport system, presumably via covalent binding with vicinal thiol groups. 15 references, 4 figures, 2 tables

  19. RISK ANALYSIS STUDY OF NOx, and SOx FROM TRANSPORTATION (CASE STUDY: MAIN STREETS OF D.I. JOGJAKARTA

    Directory of Open Access Journals (Sweden)

    Mochamad Arief Budihardjo

    2012-02-01

    Full Text Available The air pollution problems have been progressively set attention to the world especially industrialcountries recently. These problems not only give affect at health like emphysema, bronchitis, and otherinhalation disease but also make plants and properties destruction causes very big loss. This research isconcerned with the risk level which is accepted by people who reside in roadside because most of airpollutants come from transportation facilities such as motor vehicle. The limitation of the research is airpollutants exposure such like NOx, and SOx which enter the body through respiration. This risk analysisresearch is broken down into four step as follow; hazard identification showing NO2, and SO2concentration in 15 sampling locations where the highest value of NO2 is 56,5 μg / m3 and SO2 is 28,87μg/m3. According to DIY Governor Regulation No. 153 Year 2002 about the value of ambient air qualitystandard, quality standard of NO2 is 400 μg / m3, and SO2 is 900 μg / m3. It can be concluded thatconcentration of NO2 and SO2 in 2005 within all sampling locations is still under of quality standard. Thestep of exposure assessment involves the exposed population including pedicab worker, park worker, andcloister merchant. From calculation, the intake range of NO2 enters the body is 0,0025-0,0075 mg/kg.dayand SO2 is 0,0008-0,0038 mg/kg.day. Third step is dose-response assessment to find out what will be facedby people if exposure of pollutants occurs in a certain dose. The last step is risk characterization, theresult of research is that risk value / Hazard Index (HI less than 1 that still acceptable. It can besummarized that the ambient air quality of Jogjakarta especially NO2 and SO2 gas do not too adverse tohealth.

  20. Dynamic Analysis Of A Novel Manpowered Transportation Vehicle With High Mechanical Efficiency

    OpenAIRE

    Abdel Rahman, T. M; Al-Salem, Nabeel A.

    2002-01-01

    This paper evaluates the dynamics of a novel manpowered transportation vehicle. The vehicle has a novel mechanism that maximizes the mechanical input work and utilizes the weight of the rider for propulsion. The rider applies reciprocating stepping linear forces to drive chain and ratchet mechanism. The later transfer the reciprocating motion into a unidirectional rotational motion at the rear wheel to propel the vehicle. We analyzed the dynamics of the driving and transm...

  1. Structure and Mechanism of the S Component of a Bacterial ECF Transporter

    Energy Technology Data Exchange (ETDEWEB)

    P Zhang; J Wang; Y Shi

    2011-12-31

    The energy-coupling factor (ECF) transporters, responsible for vitamin uptake in prokaryotes, are a unique family of membrane transporters. Each ECF transporter contains a membrane-embedded, substrate-binding protein (known as the S component), an energy-coupling module that comprises two ATP-binding proteins (known as the A and A' components) and a transmembrane protein (known as the T component). The structure and transport mechanism of the ECF family remain unknown. Here we report the crystal structure of RibU, the S component of the ECF-type riboflavin transporter from Staphylococcus aureus at 3.6-{angstrom} resolution. RibU contains six transmembrane segments, adopts a previously unreported transporter fold and contains a riboflavin molecule bound to the L1 loop and the periplasmic portion of transmembrane segments 4-6. Structural analysis reveals the essential ligand-binding residues, identifies the putative transport path and, with sequence alignment, uncovers conserved structural features and suggests potential mechanisms of action among the ECF transporters.

  2. Modeling of glycerol-3-phosphate transporter suggests a potential 'tilt' mechanism involved in its function.

    Science.gov (United States)

    Tsigelny, Igor F; Greenberg, Jerry; Kouznetsova, Valentina; Nigam, Sanjay K

    2008-10-01

    Many major facilitator superfamily (MFS) transporters have similar 12-transmembrane alpha-helical topologies with two six-helix halves connected by a long loop. In humans, these transporters participate in key physiological processes and are also, as in the case of members of the organic anion transporter (OAT) family, of pharmaceutical interest. Recently, crystal structures of two bacterial representatives of the MFS family--the glycerol-3-phosphate transporter (GlpT) and lac-permease (LacY)--have been solved and, because of assumptions regarding the high structural conservation of this family, there is hope that the results can be applied to mammalian transporters as well. Based on crystallography, it has been suggested that a major conformational "switching" mechanism accounts for ligand transport by MFS proteins. This conformational switch would then allow periodic changes in the overall transporter configuration, resulting in its cyclic opening to the periplasm or cytoplasm. Following this lead, we have modeled a possible "switch" mechanism in GlpT, using the concept of rotation of protein domains as in the DynDom program17 and membranephilic constraints predicted by the MAPAS program.(23) We found that the minima of energies of intersubunit interactions support two alternate positions consistent with their transport properties. Thus, for GlpT, a "tilt" of 9 degrees -10 degrees rotation had the most favorable energetics of electrostatic interaction between the two halves of the transporter; moreover, this confirmation was sufficient to suggest transport of the ligand across the membrane. We conducted steered molecular dynamics simulations of the GlpT-ligand system to explore how glycerol-3-phosphate would be handled by the "tilted" structure, and obtained results generally consistent with experimental mutagenesis data. While biochemical data remain most consistent with a single-site alternating access model, our results raise the possibility that, while the "rocker switch" may apply to certain MFS transporters, intermediate "tilted" states may exist under certain circumstances or as transitional structures. Although wet lab experimental confirmation is required, our results suggest that transport mechanisms in this transporter family should probably not be assumed to be conserved simply based on standard structural homology considerations. Furthermore, steered molecular dynamics elucidating energetic interactions of ligands with amino acid residues in an appropriately modeled transporter may have predictive value in understanding the impact of mutations and/or polymorphisms on transporter function. PMID:18942157

  3. The Mechanical Design for the Darht-II Downstream Beam Transport Line

    CERN Document Server

    Westenskow, G A; Duffy, P T; Paul, A C

    2000-01-01

    This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-msec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The down-stream beam transport line is approximately 20-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 15 conventional solenoid, quadrupole and dipole magnets; as well as several speciality magnets, which transport and focus the beam to the target and to the beam dumps. There are two high power beam dumps, which are designed to absorb 80-kJ per pulse during accelerator start-up and operation. Aspects of the mechanical design of these elements are presented.

  4. The Mechanical Design for the DARHT-II Downstream Beam Transport Line

    Science.gov (United States)

    Westenskow, Glen

    This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-msec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The down-stream beam transport line is approximately 20-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 15 conventional solenoid, quadrupole and dipole magnets; as well as several speciality magnets, which transport and focus the beam to the target and to the beam dumps. There are two high power beam dumps, which are designed to absorb 80-kJ per pulse during accelerator start-up and operation. Aspects of the mechanical design of these elements are presented.

  5. Mechanism of methylmercury transport and transfer to the tissues of the rainbow trout (Salmo gairdneri)

    International Nuclear Information System (INIS)

    Hemoglobin (Hb) is the main methylmercury (Me Hg) transport protein in trout blood, binding 90 percent of whole blood MeHg as determined by gel filtration chromatography following an intragastric dose of Me 203HgCl. In vitro MeHg is taken up rapidly by red blood cells (RBC) with 84 percent of the Hg (5 ppM as MeHg) added to whole blood being accumulated by the RBCs in 3 minutes. The binding of MeHg within the RBC is freely reversible in vitro as demonstrated by the efflux of Hg from RBCs suspended in protein solutions. Trout hemolysate, containing 55 mg/ml HBB: removed 36 percent of the Hg from the RBCs in a 12 hour incubation period. The MeHg bond within the RBC is also reversible in vivo. Gel filtration chromatography of liver soluble proteins showed identical elution profiles for MeHg administered as the free salt or bound in RBCs. The number of reactive sulfhydryl (-SH) groups per molecule of Hb was found to be 4 by amperometric titration with MeHgCl. The reactive -SH concentration in the RBC was calculated to be at least 20 mM. A mechanism for the efflux of MeHg from the RBC is proposed involving the dissociation of MeHg from Hb initiated by -SH groups outside the RBC and migration of MeHg across the membrane as MeHgCl. (U.S.)

  6. Buoyancy-driven flow in a peat moss layer as a mechanism for solute transport

    OpenAIRE

    Rappoldt, C.; Pieters, G.J.J.M.; Adema, E.B.; Baaijens, G.J.; Grootjans, A.P.; Duijn, C.J. van

    2003-01-01

    Transport of nutrients, CO2, methane, and oxygen plays an important ecological role at the surface of wetland ecosystems. A possibly important transport mechanism in a water-saturated peat moss layer (usually Sphagnum cuspidatum) is nocturnal buoyancy flow, the downward flow of relatively cold surface water, and the upward flow of warm water induced by nocturnal cooling. Mathematical stability analysis showed that buoyancy flow occurs in a cooling porous layer if the system¿s Rayleigh number ...

  7. A mechanism for the fast ionic transport in nanostructured oxide-ion solid electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Bellino, M.G.; Lamas, D.G.; Walsoee de Reca, N.E. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397 (B1603ALO) Villa Martelli, Pcia. de Buenos Aires (Argentina)

    2006-11-17

    Ionic transport in nanostructured solid electrolytes is investigated using an atomistic model that clarifies the enhanced conductivity of these materials. It is based on the fast diffusion of free oxygen vacancies through the grain boundaries. A transition observed in the ionic conductivity of the nanoceramics as a function of temperature, caused by a change in the transport mechanism, is also explained. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  8. Interim results of the F-5 irradiation experiment and proposed fission product transport mechanisms

    International Nuclear Information System (INIS)

    This paper presents: (1) results of a study of gamma-scan data for eight fuel rods removed at the end of the first phase of the GCFR F-5 (X317) irradiation experiment in EBR-II; (2) a comparison of cesium and iodine migration behavior in F-5 and previous GCFR irradiation experiments (GB-9, GB-10, and F-1); and (3) proposed cesium and iodine transport mechanisms, based primarily on observed fission product behavior in the irradiation experiments. Two modes of cesium transport, metal vapor transport and xenon precursor transport, are shown to be important. The formation of cesium uranate at the fuel-blanket interface and the effect of uranate formation on cesium transport to the fuel rod trap are discussed. It is shown how cesium isotope concentrations in the fuel rod trap differ for sealed and vented rods

  9. Psychostimulants affect dopamine transmission through both dopamine transporter-dependent and independent mechanisms.

    Science.gov (United States)

    dela Pea, Ike; Gevorkiana, Ruzanna; Shi, Wei-Xing

    2015-10-01

    The precise mechanisms by which cocaine and amphetamine-like psychostimulants exert their reinforcing effects are not yet fully defined. It is widely believed, however, that these drugs produce their effects by enhancing dopamine neurotransmission in the brain, especially in limbic areas such as the nucleus accumbens, by inducing dopamine transporter-mediated reverse transport and/or blocking dopamine reuptake though the dopamine transporter. Here, we present the evidence that aside from dopamine transporter, non-dopamine transporter-mediated mechanisms also participate in psychostimulant-induced dopamine release and contribute to the behavioral effects of these drugs, such as locomotor activation and reward. Accordingly, psychostimulants could increase norepinephrine release in the prefrontal cortex, the latter then alters the firing pattern of dopamine neurons resulting in changes in action potential-dependent dopamine release. These alterations would further affect the temporal pattern of dopamine release in the nucleus accumbens, thereby modifying information processing in that area. Hence, a synaptic input to a nucleus accumbens neuron may be enhanced or inhibited by dopamine depending on its temporal relationship to dopamine release. Specific temporal patterns of dopamine release may also be required for certain forms of synaptic plasticity in the nucleus accumbens. Together, these effects induced by psychostimulants, mediated through a non-dopamine transporter-mediated mechanism involving norepinephrine and the prefrontal cortex, may also contribute importantly to the reinforcing properties of these drugs. PMID:26209364

  10. Changes of the main parameters of the primary heat transport system of the Embalse NPP after the replacement of the divider plates of the steam generators

    International Nuclear Information System (INIS)

    Divider plates of the four steam generators were repaired at Embalse NPP during the outage of 2002. This task led to a reduction of heavy water by-pass from the hot to the cold side. As a consequence of this, some Primary Heat Transport System (PHTS) parameters were affected. The main results of this work are the following: a) Bulk PHTS flow did not change significantly; b) Inlet Header temperature dropped 2,8 C degrees at full power; c) Quality at Outlet Header is now practically negligible. (author)

  11. A transition in mechanisms of size dependent electrical transport at nanoscale metal-oxide interfaces

    International Nuclear Information System (INIS)

    As device miniaturization approaches nanoscale dimensions, interfaces begin to dominate electrical properties. Here the system archetype Au/SrTiO3 is used to examine the origin of size dependent transport properties along metal-oxide interfaces. We demonstrate that a transition between two classes of size dependent electronic transport mechanisms exists, defined by a critical size ε. At sizes larger than ε an edge-related tunneling effect proportional to 1/D (the height of the supported Au nanoparticle) is observed; interfaces with sizes smaller than ε exhibit random fluctuations in current. The ability to distinguish between these mechanisms is important to future developments in nanoscale device design

  12. Towards a new generation of flow and transport models for the Aespoe Hard Rock Laboratory. Main results from the project Aespoe models 2005

    International Nuclear Information System (INIS)

    This report constitutes the outcome of a project called 'Aespoe models 2005'. The main objective of the project has been to provide a first step towards a new generation of numerical models of flow and transport, for the Aespoe HRL. In order to achieve this goal, work has been carried out along three parallel lines; discussion of basic concepts, compilation and analysis of data and model applications. A number of sub tasks are reported as appendices in the report. In fact, these appendices represent the main achievements of the project: an analysis of fracture properties, compilation of isotope and chemical data, dispersion and mixing in fractured rocks and model results. The conclusion of the project is that significant contributions to a new generation of Aespoe models have been obtained. It has further been demonstrated that working numerical simulations are up and running. Recommendations are provided for the continued work

  13. Towards a new generation of flow and transport models for the Aespoe Hard Rock Laboratory. Main results from the project Aespoe models 2005

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Urban (ed.) (Computer-aided Fluid Engineering AB (CFE AB), SE-602 10 Norrkoeping (Sweden)); Vidstrand, Patrik (Bergab AB, Goeteborg (Sweden)); Neretnieks, Ivars (Dept. of Chemical Engineering and Technology, Royal Inst. of Technology, Stockholm (Sweden)); Wallin, Bill (Geokema, Lidingoe (Sweden))

    2008-05-15

    This report constitutes the outcome of a project called 'Aespoe models 2005'. The main objective of the project has been to provide a first step towards a new generation of numerical models of flow and transport, for the Aespoe HRL. In order to achieve this goal, work has been carried out along three parallel lines; discussion of basic concepts, compilation and analysis of data and model applications. A number of sub tasks are reported as appendices in the report. In fact, these appendices represent the main achievements of the project: an analysis of fracture properties, compilation of isotope and chemical data, dispersion and mixing in fractured rocks and model results. The conclusion of the project is that significant contributions to a new generation of Aespoe models have been obtained. It has further been demonstrated that working numerical simulations are up and running. Recommendations are provided for the continued work

  14. Experimental Study on Influence of Mechanical Vibration during Transport of Transport/Storage Cask for Spent Nuclear Fuel on Containment Performance of Metal Gasket during Storage in Japan

    International Nuclear Information System (INIS)

    Transport casks of spent nuclear fuel will receive mechanical vibration during transport. It is known that the containment performance of metal gaskets is influenced by large external load or displacement. Quantitative influence of such vibration during transport on the containment performance of the metal gasket has not been known, but is crucial information particularly if the cask is stored as it is after the transport

  15. Complex Regulation of Plant Phosphate Transporters and the Gap between Molecular Mechanisms and Practical Application: What Is Missing?

    Science.gov (United States)

    Gu, Mian; Chen, Aiqun; Sun, Shubin; Xu, Guohua

    2016-03-01

    It has been almost 25 years since the first report of the gene encoding a high-affinity phosphate transporter (PT), PHO84, in yeast. Since then, an increasing number of yeast PHO84 homologs as well as other genes encoding proteins with phosphate (Pi) transport activities have been identified and functionally characterized in diverse plant species. Great progress has been made also in deciphering the molecular mechanism underlying the regulation of the abundance and/or activity of these genes and their products. The regulatory genes affect plant Pi homeostasis commonly through direct or indirect regulation of the abundance of PTs at different levels. However, little has been achieved in the use of PTs for developing genetically modified crops with high phosphorus use efficiency (PUE). This might be a consequence of overemphasizing Pi uptake from the rhizosphere and lack of knowledge about the roles of PTs in Pi transport and recycling within the plant that are required to optimize PUE. Here, we mainly focused on the genes encoding proteins with Pi transport activities and the emerging understanding of their regulation at the transcriptional, post-transcriptional, translational, and post-translational levels. In addition, we propose potential strategies for effective use of PTs in improving plant growth and development. PMID:26714050

  16. Emergency Situation Prediction Mechanism: A Novel Approach for Intelligent Transportation System Using Vehicular Ad Hoc Networks

    OpenAIRE

    Ganeshkumar, P.; Gokulakrishnan, P.

    2015-01-01

    In Indian four-lane express highway, millions of vehicles are travelling every day. Accidents are unfortunate and frequently occurring in these highways causing deaths, increase in death toll, and damage to infrastructure. A mechanism is required to avoid such road accidents at the maximum to reduce the death toll. An Emergency Situation Prediction Mechanism, a novel and proactive approach, is proposed in this paper for achieving the best of Intelligent Transportation System using Vehicular A...

  17. Tagged ozone mechanism for MOZART-4, CAM-chem, and other chemical transport models

    OpenAIRE

    Emmons, L. K.; P. G. Hess; J.-F. Lamarque; Pfister, G. G.

    2012-01-01

    A procedure for tagging ozone produced from NO sources through updates to an existing chemical mechanism is described, and results from its implementation in the Model for Ozone and Related chemical Tracers (MOZART-4), a global chemical transport model, are presented. Artificial tracers are added to the mechanism, thus not affecting the standard chemistry. The results are linear in the troposphere, i.e., the sum of ozone from individual tagged sources equals the ozone from all sources to ...

  18. Tagged ozone mechanism for MOZART-4, CAM-chem and other chemical transport models

    OpenAIRE

    Emmons, L. K.; P. G. Hess; Lamarque, J.-F.; Pfister, G. G.

    2012-01-01

    A procedure for tagging ozone produced from NO sources through updates to an existing chemical mechanism is described, and results from its implementation in the Model for Ozone and Related chemical Tracers (MOZART-4), a global chemical transport model, are presented. Artificial tracers are added to the mechanism, thus, not affecting the standard chemistry. The results are linear in the troposphere, i.e., the sum of ozone from individual tagged sources equals the ...

  19. ABC transporters as a multidrug detoxification mechanism in Rhipicephalus (Boophilus) microplus.

    Science.gov (United States)

    Pohl, Paula C; Klafke, Guilherme M; Jnior, Jos Reck; Martins, Joo Ricardo; da Silva Vaz, Itabajara; Masuda, Aoi

    2012-12-01

    ATP-binding cassette (ABC) transporters are responsible for pumping drugs across membranes and are an important drug detoxification mechanism. Since ABC transporters act on a wide spectrum of chemical compounds, they have been associated with multidrug resistance phenotype in various parasites and cancer cells. Here, we document the presence of a Rhipicephalus (Boophilus) microplus tick population (Jaguar) resistant to four acaricide classes (organophosphates (OP), synthetic pyrethroids (SP), amitraz and macrocyclic lactones (ML)) and reveal that the cattle tick has a multidrug detoxification mechanism based on ABC transporter proteins. Acaricide toxicity was assessed using the larval packet test (LPT), and mortality data were subjected to probit analysis using a susceptible strain (POA) as reference. Larvae were pre-exposed to sub-lethal doses of the ABC-transporter inhibitors, cyclosporin A (CsA) and MK571, and subsequently treated with ivermectin, abamectin, moxidectin, chlorpyriphos, cypermethrin, or amitraz in LPT. Results show that lethal concentrations 50 % (LC(50)) of ivermectin, abamectin, moxidectin (MLs), and chlorpyriphos (OP) were significantly reduced in larvae exposed to CsA and MK571 inhibitors in the Jaguar resistant population, but LC(50) did not change in POA susceptible strain larvae. LC(50) of cypermetrin (SP) and amitraz remained unchanged in inhibitor-exposed larvae, compared to larvae from Jaguar and POA strains not exposed to inhibitor. These results suggest that ABC transporter proteins can protect ticks against a wide range of acaricides and have an important implication in drug resistance development as a multidrug detoxification mechanism. PMID:22926678

  20. Growth mechanism of ZnSe single crystal by chemical vapour transport method

    International Nuclear Information System (INIS)

    We attempted to grow ZnSe single crystals by the chemical vapour transport (CVT) method using the source material with different particle diameters. The purpose of this study is to examine the dependence the growth mechanism on the source particle diameter. We observed surface topographies of grown single crystals using the ultra-high vacuum atomic force microscopy (UHV-AFM) and investigated the growth mechanism. Dislocation densities were determined from etch pit density counts. It can be seen that the transport rate is decreasing with the increase in the source particle diameter. In the case of decreasing in the transport rate, transported atoms diffuse easily on the grown surface. Moreover, it turned out that the growth mechanism changed to the two-dimensional growth from the three-dimensional growth because the transport rate decreased. The average value of EPD of 3.0x103 cm-2 was obtained. We found that control of the source particle diameter is important for preparing high-quality ZnSe single crystals

  1. Mechanical vibration: what is the importance of this physical quantity in the poultry transport?

    Directory of Open Access Journals (Sweden)

    Ana Carolina Donofre

    2014-01-01

    Full Text Available Mechanical vibrations are inherent to any system of transportation. In poultry production, the higher or lower intensity of this agent during the loading of eggs, chicks and chickens, can increase the production losses and decrease the efficiency of the system as a whole. However, despite its importance this factor is still unknown and little considered in the planning of the transport processes involved in the poultry industry. Therefore, the aim of raising the largest amount of data obtained so far to clarify the effects of mechanical vibrations already found in the transport of fertilized eggs, day-old chicks and broilers. A survey of international and national papers, from 1969 to 2014, which showed that the transport of fertilized eggs, the mechanical vibrations may be responsible for the incidence of cracks, in addition to promoting the agitation of internal constituents (yolk and albumen, which could potentially compromise the quality of birth and hatchlings. The transport of day-old chicks and broilers, the vibrations are related to situations of stress, discomfort and depreciation of the welfare of the birds, which still causes drops in the levels of glucose and corticosteroids and thus affect other parameters as the quality of the meat.

  2. Electron transport mechanism of bathocuproine exciton blocking layer in organic photovoltaics.

    Science.gov (United States)

    Lee, Jeihyun; Park, Soohyung; Lee, Younjoo; Kim, Hyein; Shin, Dongguen; Jeong, Junkyeong; Jeong, Kwangho; Cho, Sang Wan; Lee, Hyunbok; Yi, Yeonjin

    2016-02-10

    Efficient exciton management is a key issue to improve the power conversion efficiency of organic photovoltaics (OPVs). It is well known that the insertion of an exciton blocking layer (ExBL) having a large band gap promotes the efficient dissociation of photogenerated excitons at the donor-acceptor interface. However, the large band gap induces an energy barrier which disrupts the charge transport. Therefore, building an adequate strategy based on the knowledge of the true charge transport mechanism is necessary. In this study, the true electron transport mechanism of a bathocuproine (BCP) ExBL in OPVs is comprehensively investigated by in situ ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy, density functional theory calculation, and impedance spectroscopy. The chemical interaction between deposited Al and BCP induces new states within the band gap of BCP, so that electrons can transport through these new energy levels. Localized trap states are also formed upon the Al-BCP interaction. The activation energy of these traps is estimated with temperature-dependent conductance measurements to be 0.20 eV. The Al-BCP interaction induces both transport and trap levels in the energy gap of BCP and their interplay results in the electron transport observed. PMID:26821701

  3. The bacterial dicarboxylate transporter VcINDY uses a two-domain elevator-type mechanism.

    Science.gov (United States)

    Mulligan, Christopher; Fenollar-Ferrer, Cristina; Fitzgerald, Gabriel A; Vergara-Jaque, Ariela; Kaufmann, Desirée; Li, Yan; Forrest, Lucy R; Mindell, Joseph A

    2016-03-01

    Secondary transporters use alternating-access mechanisms to couple uphill substrate movement to downhill ion flux. Most known transporters use a 'rocking bundle' motion, wherein the protein moves around an immobile substrate-binding site. However, the glutamate-transporter homolog GltPh translocates its substrate-binding site vertically across the membrane, through an 'elevator' mechanism. Here, we used the 'repeat swap' approach to computationally predict the outward-facing state of the Na(+)/succinate transporter VcINDY, from Vibrio cholerae. Our model predicts a substantial elevator-like movement of VcINDY's substrate-binding site, with a vertical translation of ~15 Å and a rotation of ~43°. Our observation that multiple disulfide cross-links completely inhibit transport provides experimental confirmation of the model and demonstrates that such movement is essential. In contrast, cross-links across the VcINDY dimer interface preserve transport, thus revealing an absence of large-scale coupling between protomers. PMID:26828963

  4. Mechanical environmental transport of actinides and 137Cs from an arid radioactive waste disposal site

    International Nuclear Information System (INIS)

    Aeolian and pluvial processes represent important mechanisms for the movement of actinides and fission products at the Earth's surface. Soil samples taken in the early 1970's near a Department of Energy radioactive waste disposal site (the Subsurface Disposal Area, SDA, located in southeastern Idaho) provide a case study for studying the mechanisms and characteristics of environmental actinide and 137Cs transport in an arid environment. Multi-component mixing models suggest actinide contamination within 2.5 km of the SDA can be described by mixing between 2 distinct SDA end members and regional nuclear weapons fallout. The absence of chemical fractionation between 241Am and 239+240Pu with depth for samples beyond the northeastern corner and lack of 241Am in-growth over time (due to 241Pu decay) suggest mechanical transport and mixing of discrete contaminated particles under arid conditions. Occasional samples northeast of the SDA (the direction of the prevailing winds) contain anomalously high concentrations of Pu with 240Pu/239Pu isotopic ratios statistically identical to those in the northeastern corner. Taken together, these data suggest flooding resulted in mechanical transport of contaminated particles into the area between the SDA and a flood containment dike in the northeastern corner, following which subsequent contamination spreading in the northeastern direction resulted from wind transport of discrete particles. - Highlights: • Pu isotopic ratios from the SDA range from at least 0.059 to 0.069. • Frequent Pu “hot particles” with low Pu isotope ratios observed in samples at distance. • Similar Am/Pu ratios with depth suggest mechanical transport under arid conditions. • Data suggest mechanical flood depositino of particles in drainage ditch in 1969. • Particles subsequently resuspended/redistributed by wind

  5. The transport mechanisms of polymer nanoparticles in Caco-2 epithelial cells.

    Science.gov (United States)

    He, Bing; Lin, Ping; Jia, Zengrong; Du, Wenwen; Qu, Wei; Yuan, Lan; Dai, Wenbing; Zhang, Hua; Wang, Xueqing; Wang, Jiancheng; Zhang, Xuan; Zhang, Qiang

    2013-08-01

    As the primary physiological barrier, intestinal epithelial cells regulate the transportation of oral therapeutic agents including nanomedicines which significantly improves the bioavailability of many drugs. However, currently there seems in the lack of comprehensive understanding on nanoparticle transport in intestinal epithelial cells as well as the mechanisms related. So, in an attempt to illustrate the profile of nanoparticle transport in intestinal epithelial cells, Caco-2 cells and polymer nanoparticles (PNs) were used as the models to explore the whole transport process including endocytosis, intracellular trafficking, exocytosis and transcytosis. Via various techniques, the transport pathways of PNs in Caco-2 cells and their mechanisms were clarified. Firstly, the transport was characterized by its non-specificity. The co-mediation of clathrin, lipid raft/caveolae and macropinocytosis as well as the co-involvement of different proteins like actins, protein tyrosine kinase (PTK) and cyclooxygenase (COX) were found in the endocytosis of PNs. The endocytosed PNs could transport to apical early endosome (AEE) and then from AEE to lysososmes via AEE/late endosome (LE)/lysosome pathway, as well as to recycling endosome compartment (REC) or endoplasmic reticulum (ER) through AEE/REC and AEE/ER pathways, respectively. Both ER/Golgi and Golgi/REC/plasma membrane (PM) pathways were involved in the exocytosis of PNs. The transcytosis of PNs across the cell monolayer was very low with a ratio less than 0.5%, due to complicated reasons. Secondly, the transport was evidenced by its partial energy-dependency. Beside the energy-dependent transport mediated by some proteins, quantitative study demonstrated the obvious internalization as well as surface binding of PNs at both 37 °C and 4 °C, but significantly higher at 37 °C. Interestingly, the consistency between surface binding and internalization at each temperature was found, suggesting that cell binding was the precondition and key step for the following endocytosis. The involvement of both energy dependent and independent mechanism was also observed in the exocytosis and transcytosis process of PNs. Finally, there were opposite mechanisms found between the exocytosis and endocytosis of PNs, including the regulation role of lipid raft/caveolae, COX and Golgi complex, which also contributed to the fact of "easy entry and hard across" for PNs. Overall, this study depicts a clear picture of nanoparticle transport in Caco-2 epithelial cells characterized by non-specificity, partial energy-dependency and low transcytosis. PMID:23694903

  6. Quantum Mechanical Study on Tunnelling and Ballistic Transport of Nanometer Si MOSFETs

    International Nuclear Information System (INIS)

    Using self-consistent calculations of million-atom Schrödinger-Poisson equations, we investigate the I–V characteristics of tunnelling and ballistic transport of nanometer metal oxide semiconductor held effect transistors (MOSFET) based on a full 3-D quantum mechanical simulation under nonequilibtium condition. Atomistic empirical pseudopotentials are used to describe the device Hamiltonian and the underlying bulk band structure. We find that the ballistic transport dominates the I–V characteristics, whereas the effects of tunnelling cannot be neglected with the maximal value up to 0.8 mA/μm when the channel length of MOSFET scales down to 25 nm. The effects of tunnelling transport lower the threshold voltage Vt. The ballistic current based on fully 3-D quantum mechanical simulation is relatively large and has small on-off ratio compared with results derived from the calculation methods of Luo et al

  7. Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

    OpenAIRE

    David Rakhmilevitch; Oren Tal

    2015-01-01

    The vibration-mediated Kondo effect attracted considerable theoretical interest during the last decade. However, due to lack of extensive experimental demonstrations, the fine details of the phenomenon were not addressed. Here, we analyze the evolution of vibration-mediated Kondo effect in molecular junctions during mechanical stretching. The described analysis reveals the different contributions of Kondo and inelastic transport.

  8. Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching.

    Science.gov (United States)

    Rakhmilevitch, David; Tal, Oren

    2015-01-01

    The vibration-mediated Kondo effect attracted considerable theoretical interest during the last decade. However, due to lack of extensive experimental demonstrations, the fine details of the phenomenon were not addressed. Here, we analyze the evolution of vibration-mediated Kondo effect in molecular junctions during mechanical stretching. The described analysis reveals the different contributions of Kondo and inelastic transport. PMID:26734532

  9. Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

    Directory of Open Access Journals (Sweden)

    David Rakhmilevitch

    2015-12-01

    Full Text Available The vibration-mediated Kondo effect attracted considerable theoretical interest during the last decade. However, due to lack of extensive experimental demonstrations, the fine details of the phenomenon were not addressed. Here, we analyze the evolution of vibration-mediated Kondo effect in molecular junctions during mechanical stretching. The described analysis reveals the different contributions of Kondo and inelastic transport.

  10. Novel Transport Mechanism for Interacting Electrons in Disordered Systems: Variable-Range Resonant Tunneling

    OpenAIRE

    Baranovskii, S. D.; Shlimak, I. S.

    1998-01-01

    To interpret recent experimental observations of the phononless hopping conduction, we suggest a novel transport mechanism according to which the current-carrying single electrons move via quantum resonant tunneling between localized states brought into resonance by fast electron hops in their environment.

  11. Mechanical environmental transport of actinides and ?Cs from an arid radioactive waste disposal site.

    Science.gov (United States)

    Snow, Mathew S; Clark, Sue B; Morrison, Samuel S; Watrous, Matthew G; Olson, John E; Snyder, Darin C

    2015-10-01

    Aeolian and pluvial processes represent important mechanisms for the movement of actinides and fission products at the Earth's surface. Soil samples taken in the early 1970's near a Department of Energy radioactive waste disposal site (the Subsurface Disposal Area, SDA, located in southeastern Idaho) provide a case study for studying the mechanisms and characteristics of environmental actinide and (137)Cs transport in an arid environment. Multi-component mixing models suggest actinide contamination within 2.5 km of the SDA can be described by mixing between 2 distinct SDA end members and regional nuclear weapons fallout. The absence of chemical fractionation between (241)Am and (239+240)Pu with depth for samples beyond the northeastern corner and lack of (241)Am in-growth over time (due to (241)Pu decay) suggest mechanical transport and mixing of discrete contaminated particles under arid conditions. Occasional samples northeast of the SDA (the direction of the prevailing winds) contain anomalously high concentrations of Pu with (240)Pu/(239)Pu isotopic ratios statistically identical to those in the northeastern corner. Taken together, these data suggest flooding resulted in mechanical transport of contaminated particles into the area between the SDA and a flood containment dike in the northeastern corner, following which subsequent contamination spreading in the northeastern direction resulted from wind transport of discrete particles. PMID:26107287

  12. Molecular characterisation of transport mechanisms at the developing mouse blood-CSF interface

    DEFF Research Database (Denmark)

    Liddelow, Shane A; Temple, Sally; Møllgård, Kjeld; Gehwolf, Renate; Wagner, Andrea; Bauer, Hannelore; Bauer, Hans-Christian; Phoenix, Timothy N; Dziegielewska, Katarzyna M; Saunders, Norman R

    2012-01-01

    of albumin from blood to cerebrospinal fluid. In adult plexus this pattern of immunostaining was absent. We propose a model of the cellular mechanism in which SPARC and GYPA, together with identified vesicle-associated membrane proteins (VAMPs) may act as receptors/transporters in developmentally...... coding for key functions (intercellular/tight junctions, influx/efflux transporters) changed expression during development and their expression patterns are discussed in the context of available physiological/permeability results in the developing brain. Three genes: Secreted protein acidic and rich in......-immunopositive. Results showed a significant degree of concordance between plasma protein/albumin immunoreactivity and expression of the putative transporters. Immunohistochemistry identified SPARC and GYPA in choroid plexus epithelial cells in the embryo with a subcellular distribution that was consistent with transport...

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

    CERN Document Server

    Kou, Wenjun; Griffith, Boyce E; Pandolfino, John E; Kahrilas, Peter J; Patankar, Neelesh A

    2015-01-01

    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, which is modeled as an actively contracting, fiber-reinforced tube. A simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are then 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 i...

  14. Filtration as the main transport mechanism of protein exchange between plasma and the peritoneal cavity in hepatic cirrhosis

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl; Lassen, N A; Parving, H H; Winkler, K

    1980-01-01

    Fractional peritoneal reabsorption rates (FPRR) were determined from the plasma activity after simultaneous intraperitoneal injection of 131I-labelled serum albumin (a) and 125I-labelled immunoglobulin G-IgG (g) in eight patients with cirrhosis (+ ascites 6, -ascites 2) and in one patient with...... carcinomatous ascites. Trans-vascular escape rates of albumin (TERa) and IgG (TERg) were determined in the cirrhotic patients from the disappearance of simultaneously intravenously injected 131I-labelled serum albumin and 124I-labelled IgG. Peritoneal space to plasma appearance times ranged 0.1-3.3 h, and the...... appearance times of albumin and IgG were almost identical. In patients with cirrhosis FPRRa and FPRRg were on average 1.27 and 1.21% of intraperitoneal protein masses returning to plasma per hour, respectively. Mean FPRRg/FPRRa ratio was 0.95 and this value was not significantly different from unity, but...

  15. Rupture mechanics of metallic alloys for hydrogen transport; Mecanique de la rupture des alliages metalliques pour le transport de l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Moro, I.; Briottet, L.; Lemoine, P. [CEA Grenoble (DRT/LITEN/DTH/LEV), 38 (France); Andrieu, E.; Blanc, C. [Centre Interuniversitaire de Recherche et d' Ingenierie des Materiaux (ENSIACET/CIRIMAT), 31 - Toulouse (France)

    2007-07-01

    With the aim to establish a cheap hydrogen distribution system, the transport by pipelines is a solution particularly interesting. Among the high limit of elasticity steels, the X80 has been chosen for hydrogen transport. Its chemical composition and microstructure are given. Important microstructural changes have been revealed in the sheet thickness: the microstructure is thinner and richer in perlite in surface than in bulk. In parallel to this microstructural evolution, a microhardness gradient has been observed: the material microhardness is stronger in surface than in bulk of the sheet. The use of this material for hydrogen transport requires to study its resistance to hydrogen embrittlement. The main aim of this work is to develop an easy rupture mechanics test allowing to qualify the studied material in a gaseous hydrogen environment, to determine the sensitivity of the studied material to the hydrogen embrittlement and to better understand the mechanisms of the hydrogen embrittlement for ferritic materials. Two experimental tests have been used for: the first one is a traction machine coupled to an autoclave; the second one allows to carry out disk rupture tests. The toughness of the material in a gaseous hydrogen environment has thus been determined. The resistance of the material to hydrogen embrittlement has been characterized and by simulation, it has been possible to identify the areas with a strong concentration in hydrogen. The second aim of this work is to study the influence of the steel microstructure on the hydrogen position in the material and on the resistance of the material to the hydrogen embrittlement. The preferential trapping sites on the material not mechanically loaded have at first been identified, as well as the hydrogen position on the different phases and at the ferrite/cementite interface. The interaction between the mechanical loads, the position and the trapping of the hydrogen have been studied then. At last, has been established a link between the preferential localization of hydrogen and the results of the rupture mechanics tests in a gaseous hydrogen environment. (O.M.)

  16. Receptor-mediated mechanism for the transport of prolactin from blood to cerebrospinal fluid

    International Nuclear Information System (INIS)

    Prolactin (PRL) interacts with areas of the central nervous system which reside behind the blood-brain barrier. While vascular PRL does not cross this barrier, it is readily accessible to the cerebrospinal fluid (CSF) from which it may gain access to the PRL-responsive areas of the brain. Studies were undertaken to characterize the mechanism responsible for the translocation of PRL from blood to CSF. Rats were given external jugular vein injections of [125-I]iodo-PRL in the presence or absence of an excess of unlabeled ovine PRL (oPRL), human GH, bovine GH, or porcine insulin. CSF and choroid plexus were removed 60 min later. CSF samples were electrophoresed on sodium dodecyl sulfate-polyacrylamide slab gels and resultant autoradiographs were analyzed with quantitative microdensitometry. The data revealed that unlabeled lactogenic hormones, viz. oPRL and human GH, caused a statistically significant inhibition of [125I]iodo-PRL transport from blood to CSF. In contrast, nonlactogenic hormones, viz bovine GH and insulin, had no effect on [125I]iodo-PRL transport into the CSF. An identical pattern of competition was observed in the binding of hormone to the choroid plexus. Furthermore, vascular injections of [125I]iodo-PRL administered with a range of concentrations of unlabeled oPRL revealed a dose-response inhibition in the transport of [125I]iodo-PRL from blood to CSF. The study demonstrates that PRL enters the CSF by a specific, PRL receptor-mediated transport mechanism. The data is consistent with the hypothesis that the transport mechanism resides at the choroid plexus. The existence of this transport mechanism reflects the importance of the cerebroventricular system in PRL-brain interactions

  17. Investigation on the oxygen transport mechanisms in the Sarcheshmeh waste rock dumps

    Directory of Open Access Journals (Sweden)

    Saeed Yousefi

    2015-04-01

    Full Text Available Introduction Pyrite oxidation and acid mine drainage (AMD are the serious environmental problems associated with the mining activities in sulphide ores. The rate of pyrite oxidation is governed by the availability of oxygen (Borden, 2003. Therefore, the identifying oxygen supplying mechanism is one of the most important issues related to the environmental assessment of waste rock dumps (Cathles and Apps, 1975; Jaynes et al., 1984; Davis and Ritchie, 1986. Although comprehensive researches were performed on the mathematical description of oxygen transport processes using the numerical modeling (Morin et al., 1988; Blowes et al., 1991; Wunderly et al., 1986; Elberling et al., 1994; Jannesar Malakooti et al., 2014, so far, the interactions between these processes and geochemical and mineralogical characteristics has not been studied especially in waste rock dumps. Therefore the main objective of this study is to identify the evidences for knowing the oxygen transport mechanisms in the waste dumps and also, its role in intensity of pyrite oxidation. It is expected that such these structural studies could be useful for better understanding of dominant processes in numerical modeling and also providing environmental management strategies in the study area and other sites by similar characteristics. Materials and Methods In this study, thirty solid samples were collected from six excavated trenches in the waste rock dumps No. 19 and 31 of the Sarcheshmeh porphyry copper mine. Collected samples were studied using several methods such as XRD, ASTM-D2492, paste pH and grain size distribution. The results obtained from these methods were used with the field observations in order to characterize some detail information about oxygen supplying mechanisms for oxidation reactions in the waste rock dumps. Result The main minerals found by the XRD analysis were quartz and muscovite which were present in all samples. Pyrite, orthose, albite, and chlorite were also present in some samples. The carbonate content as the major neutralizing agent was zero in all samples. Due to the presence of sulfide minerals, mainly as pyrite, and also lack of any carbonate minerals, the AMD generation from the Sarcheshmeh waste rocks during the weathering reactions is predictable. At the Sarcheshmeh mine waste, several secondary minerals such as butlerite, jarosite and gypsum were detected by XRD at some depths. Moreover, amorphous iron oxyhydroxide minerals visually observed in waste dumps were not detected by XRD due to being negligible and low level of crystallinity. Hence, they were measured in terms of (Feo-h by ASTM standard test method. The ASTM-D2492 standard test showed that pyrite, sulphate and iron oxyhydroxide minerals (Feo-h are present in all samples. Against the XRD method, the test even detected the negligible content of the minerals. The paste pH tests showed that 15 samples were acid-producing because they had pH lower than 4. On the basis of moisture content results, the samples by name A6, A7, B1 and B2 showed high level of moisture which can be sign of the particular status in them. Discussion According to the field observations, channels with a strong flow of warm and humid air were detected in the depth of 3 to 5 meters of the investigated waste rock dumps. High content of humidity (8.25 and 13.43 percent and sulfate (4.5 and 7.02 percent were observed together with low content of pyrite (1.5 and 6.23 percent and acidic paste pH values (3.13 and 2.88 around these channels. Therefore, from the relation of these occurrences, it can be inferred that the air convection is important for supply oxygen to pyrite oxidation in the waste dumps of Sarcheshmeh. The results also indicate that, two main factors including grain size distribution and formation of hardpan layer on top of old weathered rocks are responsible for the decreasing of oxygen transformation rate via the molecular diffusion mechanism through the waste rock dumps. Considering the presence of coarse grain and poorly graded material as a proper media for air convection and also hardpan layer as a confining factor in molecular diffusion of oxygen, it can be deduced that the air convection is the main important mechanism to supply oxygen for weathering and oxidation reactions in the waste rock dumps. The abundance of oxygen and high temperatures in such conditions are also favorable for bacterial activities, which can then accelerate the pyrite oxidation in lower depth of dump. It is expected that the results of this study could be useful as a basis for providing the remediation strategies to control acidic drainage. So that knowing the domination of air convection and presence of hardpan justify controlling the flux of oxygen from the coarse material in bottom of waste dump. Therefore, it would be wrong to construct the impermeable layer on the surface of waste dump for arresting the oxygen diffusion as a traditional method in the remediation. Acknowledgement The authors appreciate the cooperation of the Research and Development Division of the Sarcheshmeh Copper Complex for financial support and access to sampling and analysis facilities. Reference Blowes, D.W., Reardon, E.J., Jambor, J.L. and Cherry, J.A., 1991. The formation and potential importance of cemented layers in inactive sulfide mine tailings. Geochimica et Cosmochimica Acta, 55(4: 965-978. Borden, R.K., 2003. Environmental geochemistry of the Bingham Canyon porphyry copper deposit, Utah. Environmental Geology, 43(7: 752-758. Cathles, L.M. and Apps, J.A., 1975. A model of the dump leaching process that incorporates oxygen balance, heat balance, and air convection. Metallurgical Transactions B, 6(4: 617-624. Davis, G.B. and Ritchie A.I.M., 1986. A model of oxidation in pyritic mine wastes: part 1: Equations and approximate solution. Applied Mathematical Modeling, 10(5: 314-322. Elberling, B., Nicholson, R.V., Reardon, E.J. and Tibble, R., 1994. Evaluation of sulphide oxidation rates: a laboratory study comparing oxygen fluxes and rates of oxidation product release. Canadian Geotechnical Journal, 31(3: 375-383. Jannesar Malakooti, S., Shafaei Tonkaboni, S.Z., Noaparast, M., Ardejani, F.D. and Naseh, R., 2014. Characterisation of the Sarcheshmeh copper mine tailings, Kerman province, southeast of Iran. Environmental Earth Sciences, 71(5: 2267-2291. Jaynes, D.B., Rogowski, A.S. and Pionke, H.B., 1984. Acid mine drainage from reclaimed coal strip mines 1. Model description. Water Resources Research, 20(2: 233-242. Morin, K.A., Cherry, J.A., Dave, N.K., Lim, T.P. and Vivyurka, A.J., 1988. Migration of acidic groundwater seepage from uranium-tailings impoundments, 1. Field study and conceptual hydrogeochemical model. Journal of Contaminant Hydrology, 2(4: 271-303. Wunderly, M.D., Blowes, D.W., Frind, E.O. and Ptacek, C.J., 1986. Sulfide mineral oxidation and subsequent reactive transport of oxidation products in mine tailings impoundments: A numerical model. Water Resources Research, 32(10: 3173-3187.

  18. OPTIMIZATION OF REGULATORY MECHANISMS AS A CONDITION OF COMPETITIVE TRANSPORT COMPLEX

    Directory of Open Access Journals (Sweden)

    S. Ilchenko

    2012-06-01

    Full Text Available At the present time for confident entrance to the European transport system with its standards, technical, organizational and ecological norms, the transport network of regions and the whole Ukraine requires constant qualitative updating. A number of important actions in this direction are already carried out, at the same time, to maintain an effective utilization of the international transport corridors in new conditions, it is important to reach the ultimate coordination of actions of all participants in this sphere.Complexity and immensity of the problems connected to the improvement of management of transport systems, leads to the necessity of an overall problem solution of the balanced transport development, transport systems and multi-modal transport development as a basic element of domestic potential growth of the state. Maintenance of these processes should be carried out through working out the programs of national transport system development and regional development programs in this direction. Therefore a research problem is to lay out the recommendations and methodical approaches to the problems of realization the above-stated programs and development strategy.In the presented article the basic problems of realization of the assigned tasks are designated, the principles underlying their performance are constructed, the legislative base which represents a legal mechanism of programs realization is defined, and recommendations which will give the chance to provide dynamic balanced development of a transport network of the country are presented. All these factors will help bring into the standards of living to the European ones and to create conditions for economic activity strengthening in all regions of the country that will contribute gradual easing of inter-regional disproportion, reduction of risks of formation of depressive territories and will protect society from considerable expenses on renewal of appropriate conditions of their ability to live.

  19. A review of overseas financing mechanisms and incentives for commercial renewable energy projects. V. 1: Main report

    International Nuclear Information System (INIS)

    Overseas financing mechanisms and incentives for commercial renewable energy projects being undertaken worldwide are reviewed in this study funded by the United Kingdom Department of Trade and Industry. The study examines how commercial renewable energy projects have been financed in Europe and North America. Future trends are suggested. Financial, contractual or market incentives for each technology are examined for each country. Incentive programmes are evaluated and analysed in terms of cost to the government and consumer. The potential and issues involved for British companies aiming to export expertise or equipment for such projects is also evaluated briefly. (UK)

  20. Use of molecular modelling to probe the mechanism of the nucleoside transporter NupG

    Science.gov (United States)

    Vaziri, Hamidreza; Baldwin, Stephen A.; Baldwin, Jocelyn M.; Adams, David G.; Young, James D.

    2013-01-01

    Nucleosides play key roles in biology as precursors for salvage pathways of nucleotide synthesis. Prokaryotes import nucleosides across the cytoplasmic membrane by proton- or sodium-driven transporters belonging to the Concentrative Nucleoside Transporter (CNT) family or the Nucleoside:H+ Symporter (NHS) family of the Major Facilitator Superfamily. The high resolution structure of a CNT from Vibrio cholerae has recently been determined, but no similar structural information is available for the NHS family. To gain a better understanding of the molecular mechanism of nucleoside transport, in the present study the structures of two conformations of the archetypical NHS transporter NupG from Escherichia coli were modelled on the inward- and outward-facing conformations of the lactose transporter LacY from E. coli, a member of the Oligosaccharide:H+ Symporter (OHS) family. Sequence alignment of these distantly related proteins (? 10% sequence identity), was facilitated by comparison of the patterns of residue conservation within the NHS and OHS families. Despite the low sequence similarity, the accessibilities of endogenous and introduced cysteine residues to thiol reagents were found to be consistent with the predictions of the models, supporting their validity. For example C358, located within the predicted nucleoside binding site, was shown to be responsible for the sensitivity of NupG to inhibition by p-chloromercuribenzene sulphonate. Functional analysis of mutants in residues predicted by the models to be involved in the translocation mechanism, including Q261, E264 and N228, supported the hypothesis that they play important roles, and suggested that the transport mechanisms of NupG and LacY, while different, share common features. PMID:23256604

  1. Mechanical thermal and electric measurements on materials and components of the main coils of the Milan superconducting cyclotron

    International Nuclear Information System (INIS)

    The coils of the Milan Superconducting Cyclotron are the largest superconducting devices built up to now in Italy and constitute the first superconducting magnet for accelerator in Europe. Because of the large stored energy (more than 40 MJ), of the high stresses and of of the need of reliability, a lot of measurements were carried out as well on materials used for the coils, both on superconducting cable and structural materials, as on the main components of the coils and on two double pancakes prototypes (wound with full copper cable). In this paper the results on these measurements are reported and the results of tests on the prototypes are discussed. The aim is to provide an easy source of data for superconducting coils useful to verify calculations or to improve the performances

  2. Species Transport Mechanisms Governing Crossover and Capacity Loss in Vanadium Redox Flow Batteries

    Science.gov (United States)

    Agar, Ertan

    Vanadium redox flow batteries (VRFBs) are an emerging energy storage technology that offers unique advantages for grid-scale energy storage due to their flexible design and decoupled power/energy feature. Despite their popularity, a series of technical challenges hinder their widespread implementation. Among these, capacity loss (i.e., loss of energy storage capability) due to the undesired species crossover across the membrane has been identified as the key issue limiting the longevity of these systems. This issue is primarily governed by the properties of the membrane and can be mitigated by using proper membrane architectures with desired features. Presently, identifying proper membrane architectures for VRFB systems is hampered by the lack of a fundamental understanding of the nature of species transport mechanisms and how they are related to the membrane properties and key operating conditions. This Ph.D. study seeks to address this critical challenge by exploring the fundamental mechanisms responsible for species transport within the membrane. The overall objective of this dissertation study is to establish a fundamental understanding of the multi-ionic transport in VRFB membranes by investigating the ionic transport mechanisms responsible for crossover, and utilize this understanding to reveal the role of membrane properties and operating conditions on the capacity loss. To achieve these goals, a combined experimental and computational study was designed. An experimentally validated, 2-D, transient VRFB model that can track the vanadium crossover and capture the related capacity loss was developed. In addition to the model, several electrochemical techniques were used to characterize different types of membrane and study the effects of various operating conditions on the species crossover. Using these computational and experimental tools, an in-depth understanding of the species transport mechanisms within the membrane and how they are related to membrane properties and operating conditions of VRFBs has been obtained. Finally, this understanding was utilized to identify effective mitigation strategies to minimize the capacity fade and improve the long-term performance of these systems.

  3. Mechanical and fracture behavior of nuclear fuel cladding in terms of transport and temporary dry storage; Comportamiento mecanio y en fractura de vainas de combustible nuclear en condiciones de transporte y almacenamiento temporal en seco

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz Hervias, J.; Martin Rengel, M. A.; Gomez, F. J.

    2012-11-01

    In this work, the most relevant results of a research project on the mechanical and fracture behavior of cladding in transport and dry storage conditions are summarized. the project is being carried out at Universidad Politecnica de Madrid in collaboration with ENUSA, ENRESA and CSN. Non-irradiated cladding is investigated. The main objective is to determine a failure criterion of cladding as a function of hydrogen content, temperature and strain rate. (Author)

  4. Mechanism for Particle Transport and Size Sorting via Low-Frequency Vibrations

    Science.gov (United States)

    Sherrit, Stewart; Scott, James S.; Bar-Cohen, Yoseph; Badescu, Mircea; Bao, Xiaoqi

    2010-01-01

    There is a need for effective sample handling tools to deliver and sort particles for analytical instruments that are planned for use in future NASA missions. Specifically, a need exists for a compact mechanism that allows transporting and sieving particle sizes of powdered cuttings and soil grains that may be acquired by sampling tools such as a robotic scoop or drill. The required tool needs to be low mass and compact to operate from such platforms as a lander or rover. This technology also would be applicable to sample handling when transporting samples to analyzers and sorting particles by size.

  5. The Mechanical Design for the Darht-II Downstream Beam Transport Line

    OpenAIRE

    Westenskow, G. A.; Bertolini, L. R.; Duffy, P. T.; Paul, A.C.

    2000-01-01

    This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-msec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The down-stream beam transport line is approximately 20-meter long region extending from the e...

  6. The mechanism of the NH4 ion oscillatory transport across the excitable cell membrane

    Directory of Open Access Journals (Sweden)

    Radenović Čedomir N.

    2005-01-01

    Full Text Available This paper presents results on typical oscillations of the membrane potential induced by the excitation of the cell membrane by different concentrations of the NH4Cl solution. The existence of four classes of oscillations of the membrane potential and several different single and local impulses rhythmically occurring were determined. It is known that the oscillatory processes of the membrane potential are in direct dependence on oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane. A hypothesis on a possible mechanism of oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane is also presented.

  7. The transport mechanism of cadmium by the small intestine of rats

    International Nuclear Information System (INIS)

    The mechanism of cadmium absorption was studied in vitro using the sacs of small intestines of male Sprague-Dawley rats. Relation between the concentration of cadmium in the mucosal fluid and the rate of transport of 109Cd to the serosal fluid showed that the higher the concentration of cadmium, the greater the transport of 109Cd. Wall uptake of 109Cd was limited, and could be saturated at relatively low concentration. 109Cd transport was not proportional to the cadmium concentration on the mucosal side, nor to the concentration of cadmium taken up by the intestinal walls. At the initial cadmium concentration of 50 μg/ml, there was no significant effect on the retention of 109Cd in the intestinal walls, inspite of extremely large increase in the amount of 109Cd transport into the serosal fluid. Cadmium could be transported across the intestinal walls against a gradient when the initial cadmium concentration on the mucosal side was raised to 50 μg/ml, which showed that the passage of 109Cd across the intestinal walls could not be the result of uptake by the walls from the mucosal fluid, followed by simple diffusion into the serosal fluid. Cadmium transport through and retention within the intestinal walls was reduced by preliminary cadmium treatment, and it suggests that it induced some change in the permeability of the intestinal walls that facilitated the transmural passage of 109Cd. (Kaihara, S.)

  8. ATP binding drives substrate capture in an ECF transporter by a release-and-catch mechanism.

    Science.gov (United States)

    Karpowich, Nathan K; Song, Jin Mei; Cocco, Nicolette; Wang, Da-Neng

    2015-07-01

    ECF transporters are a family of active transporters for vitamins. They are composed of four subunits: a membrane-embedded substrate-binding subunit (EcfS), a transmembrane coupling subunit (EcfT) and two ATP-binding-cassette ATPases (EcfA and EcfA'). We have investigated the mechanism of the ECF transporter for riboflavin from the pathogen Listeria monocytogenes, LmECF-RibU. Using structural and biochemical approaches, we found that ATP binding to the EcfAA' ATPases drives a conformational change that dissociates the S subunit from the EcfAA'T ECF module. Upon release from the ECF module, the RibU S subunit then binds the riboflavin transport substrate. We also find that S subunits for distinct substrates compete for the ATP-bound state of the ECF module. Our results explain how ECF transporters capture the transport substrate and reproduce the in vivo observations on S-subunit competition for which the family was named. PMID:26052893

  9. Alternating-access mechanism in conformationally asymmetric trimers of the betaine transporter BetP.

    Science.gov (United States)

    Perez, Camilo; Koshy, Caroline; Yildiz, Ozkan; Ziegler, Christine

    2012-10-01

    Betaine and Na(+) symport has been extensively studied in the osmotically regulated transporter BetP from Corynebacterium glutamicum, a member of the betaine/choline/carnitine transporter family, which shares the conserved LeuT-like fold of two inverted structural repeats. BetP adjusts its transport activity by sensing the cytoplasmic K(+) concentration as a measure for hyperosmotic stress via the osmosensing carboxy-terminal domain. BetP needs to be in a trimeric state for communication between individual protomers through several intratrimeric interaction sites. Recently, crystal structures of inward-facing BetP trimers have contributed to our understanding of activity regulation on a molecular level. Here we report new crystal structures, which reveal two conformationally asymmetric BetP trimers, capturing among them three distinct transport states. We observe a total of four new conformations at once: an outward-open apo and an outward-occluded apo state, and two closed transition states--one in complex with betaine and one substrate-free. On the basis of these new structures, we identified local and global conformational changes in BetP that underlie the molecular transport mechanism, which partially resemble structural changes observed in other sodium-coupled LeuT-like fold transporters, but show differences we attribute to the osmolytic nature of betaine, the exclusive substrate specificity and the regulatory properties of BetP. PMID:22940865

  10. Structure and transport mechanisms of Si/porous Si n-p junctions prepared by liquid phase epitaxy

    International Nuclear Information System (INIS)

    Heterojunction devices of n-Si/p-PSi were fabricated by growing n-Si films onto p-type porous Si substrates by liquid phase epitaxy. The structure of the grown films was checked using scanning electron microscopy and X-ray diffraction spectroscopy. X-ray diffraction measurements showed that the grown films have monocrystalline structure oriented along (1 1 1) direction with mainly cubic phase. Current-voltage (I-V) and capacitance-voltage (C-V) characteristics were measured over the temperature range from 298 to 398 K. The analysis of the dark I-V characteristics of n-Si/p-PSi at several temperatures is done to elucidate the conduction mechanisms and the evaluation of the heterojunction parameters is presented. Two carrier transport mechanisms are believed to be at the origin of the forward current. At low bias voltage (V ≤ 0.4 V) the forward current is dominated by the recombination at the porous silicon side of the space charge region. In the 0.5 V ≤ V ≤ 1.4 V region, the current transport is due to the space charge-limited current mechanism dominated by a single trapping level of energy 0.41 eV. The reverse current is considered to be mainly generated in the depletion region of the porous silicon. The capacitance-voltage results confirm an abrupt junction with a homogenous distribution of the impurities inside the space charge region. Information on the depletion region, built-in voltage and net carrier concentration were obtained from the dark C-V characteristics.

  11. Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

    Energy Technology Data Exchange (ETDEWEB)

    Bobkov, K K; Rybaltovsky, A A; Vel' miskin, V V; Likhachev, M E; Bubnov, M M; Dianov, E M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Umnikov, A A; Gur' yanov, A N; Vechkanov, N N [G.G.Devyatykh Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation); Shestakova, I A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2014-12-31

    We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb{sup 2+} ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb{sup 2+} ions and aluminium – oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicate glass, has been identified: photoinduced Yb{sup 3+} charge-transfer state excitation. (optical fibres)

  12. Impact of mechanical- and maintenance-induced failures of main reactor coolant pump seals on plant safety

    International Nuclear Information System (INIS)

    This document presents an investigation of the safety impact resulting from mechanical- and maintenance-induced reactor coolant pump (RCP) seal failures in nuclear power plants. A data survey of the pump seal failures for existing nuclear power plants in the US from several available sources was performed. The annual frequency of pump seal failures in a nuclear power plant was estimated based on the concept of hazard rate and dependency evaluation. The conditional probability of various sizes of leak rates given seal failures was then evaluated. The safety impact of RCP seal failures, in terms of contribution to plant core-melt frequency, was also evaluated for three nuclear power plants. For leak rates below the normal makeup capacity and the impact of plant safety were discussed qualitatively, whereas for leak rates beyond the normal make up capacity, formal PRA methodologies were applied. 22 refs., 17 figs., 19 tabs

  13. Mechanism of NaCl transport-stimulated prostaglandin formation in MDCK cells

    International Nuclear Information System (INIS)

    Recently the authors have found that stimulation of NaCl transport in high-resistance MDCK cells enhances their prostaglandin formation. In the present study, they investigated the mechanisms by which prostaglandin formation, measured by radioimmunoassay, could be linked to the ion transport in these cells. They found that stimulation of transport caused a transient stimulation of prostaglandin formation lasting 5-10 min. The rise in prostaglandin formation was paralleled by a rise of free intracellular [14C]-arachidonic acid. Analysis of membrane lipids revealed that the rise of free arachidonic acid was paralleled by a loss of arachidonic acid from polyphosphoinositides. They failed to obtain indications for the stimulation of calcium-dependent phospholipase A2. However, they did obtain evidence that the incorporation of arachidonic acid into phospholipids was diminished during stimulation of ion transport, indicating a decreased rate of reesterification. Despite the fact that there was no significant fall in total cellular ATP on stimulation of ion transport, they found a high and transient rise of lactate production of the cells on stimulation of the [45Ca]-ion transport indicating an alteration of the ADP/ATP ratio. The results suggest that an increase in the rate of sodium chloride transport by MDCK cells stimulates formation by an inhibition of reesterification of free arachidonic acid. Reesterification of arachidonic acid is most likely inhibited by a local and transient fall of ATP at the basal membrane side, which is caused by the enhanced ATP consumption of the sodium potassium adenosine triphosphatase (ATPase) during stimulation of ion transport

  14. Long-range transport of Asian pollution to North America: Mechanisms, chemistry and variability

    Science.gov (United States)

    Liang, Qing

    Long-range transport (LRT) of Asian pollutants affects the atmospheric composition over the North Pacific and has important implications in terms of air quality regulation in the United States. Through analysis of surface and aircraft observations with a global model of tropospheric chemistry, this dissertation investigates the mechanisms, chemistry, and variability of long-range transport of Asian pollution. This study has resulted in three papers, two of which have been published in the Journal of Geophysical Research - Atmospheres (Chapter 2 and 3), and one is in preparation for submission to the same journal (Chapter 4). Chapter 2 examines observations of carbon monoxide (CO, a tracer for anthropogenic emissions) in the North Pacific to understand the seasonality and transport of Asian pollution. The Asian influence on the North Pacific troposphere maximizes during spring and minimizes in summer, but LRT occurs throughout the year. We find that 80% of the export episodes over East Asia are mediated by mid-latitude cyclones and 3/4 of the events imported into the lower troposphere over the NE Pacific are by boundary layer transport. Chapter 3 focuses on the daily to interannual variability of transpacific transport. We relate the daily variability in Asian outflow to the passage of mid-latitude cyclones in East Asia, while transpacific transport is linked to the intensity of the Pacific High and the Aleutian low. On interannual timescales, we find that the variability in transpacific transport is favored by a strong Pacific High and a strong Aleutian Low. Chapter 4 focuses on observations of Asian pollution plumes in the free troposphere over North America during summer. The summertime Asian plumes are enhanced in many trace gases compared to background. When contrasted with previous springtime measurements, the summertime transport plumes show much higher levels of reactive nitrogen species and ozone as a result of active photochemistry.

  15. Haemophilus parainfluenzae expresses diverse lipopolysaccharide O-antigens using ABC transporter and Wzy polymerase-dependent mechanisms.

    Science.gov (United States)

    Young, Rosanna E B; Twelkmeyer, Brigitte; Vitiazeva, Varvara; Power, Peter M; Schweda, Elke K H; Hood, Derek W

    2013-12-01

    Lipopolysaccharide O-antigens are the basis of serotyping schemes for Gram negative bacteria and help to determine the nature of host-bacterial interactions. Haemophilus parainfluenzae is a normal commensal of humans but is also an occasional pathogen. The prevalence, diversity and biosynthesis of O-antigens were investigated in this species for the first time. 18/18 commensal H. parainfluenzae isolates contain a O-antigen biosynthesis gene cluster flanked by glnA and pepB, the same position as the hmg locus for tetrasaccharide biosynthesis in Haemophilus influenzae. The O-antigen loci show diverse restriction digest patterns but fall into two main groups: (1) those encoding enzymes for the synthesis and transfer of FucNAc4N in addition to the Wzy-dependent mechanism of O-antigen synthesis and transport and (2) those encoding galactofuranose synthesis/transfer enzymes and an ABC transporter. The other glycosyltransferase genes differ between isolates. Three H. parainfluenzae isolates fell outside these groups and are predicted to synthesise O-antigens containing ribitol phosphate or deoxytalose. Isolates using the ABC transporter system encode a putative O-antigen ligase, required for the synthesis of O-antigen-containing LPS glycoforms, at a separate genomic location. The presence of an O-antigen contributes significantly to H. parainfluenzae resistance to the killing effect of human serum in vitro. The discovery of O-antigens in H. parainfluenzae is striking, as its close relative H. influenzae lacks this cell surface component. PMID:24035104

  16. Haemophilus parainfluenzae expresses diverse lipopolysaccharide O-antigens using ABC transporter and Wzy polymerase-dependent mechanisms

    Science.gov (United States)

    Young, Rosanna E.B.; Twelkmeyer, Brigitte; Vitiazeva, Varvara; Power, Peter M.; Schweda, Elke K.H.; Hood, Derek W.

    2013-01-01

    Lipopolysaccharide O-antigens are the basis of serotyping schemes for Gram negative bacteria and help to determine the nature of hostbacterial interactions. Haemophilus parainfluenzae is a normal commensal of humans but is also an occasional pathogen. The prevalence, diversity and biosynthesis of O-antigens were investigated in this species for the first time. 18/18 commensal H. parainfluenzae isolates contain a O-antigen biosynthesis gene cluster flanked by glnA and pepB, the same position as the hmg locus for tetrasaccharide biosynthesis in Haemophilus influenzae. The O-antigen loci show diverse restriction digest patterns but fall into two main groups: (1) those encoding enzymes for the synthesis and transfer of FucNAc4N in addition to the Wzy-dependent mechanism of O-antigen synthesis and transport and (2) those encoding galactofuranose synthesis/transfer enzymes and an ABC transporter. The other glycosyltransferase genes differ between isolates. Three H. parainfluenzae isolates fell outside these groups and are predicted to synthesise O-antigens containing ribitol phosphate or deoxytalose. Isolates using the ABC transporter system encode a putative O-antigen ligase, required for the synthesis of O-antigen-containing LPS glycoforms, at a separate genomic location. The presence of an O-antigen contributes significantly to H. parainfluenzae resistance to the killing effect of human serum in vitro. The discovery of O-antigens in H. parainfluenzae is striking, as its close relative H. influenzae lacks this cell surface component. PMID:24035104

  17. Excess white noise to probe transport mechanisms in a membrane channel

    Science.gov (United States)

    Queralt-Martín, María; López, M. Lidón; Alcaraz, Antonio

    2015-06-01

    Current fluctuation analysis has been successfully used over the years to investigate the physical properties of different systems. Here, we perform single-channel time-resolved current experiments in a protein channel to evaluate the different transport mechanisms governing the channel function. Using different salts of monovalent and divalent cations in a wide range of concentrations and applied potentials, we analyze current fluctuations focusing on the voltage dependence of the additional white noise that appears in the low-frequency range of the spectra. We demonstrate that the channel displays two characteristic transport regimes: at low salt concentrations (10 mM to 1 M) ion permeation is controlled by the protein fixed charges that induce accumulation or exclusion of ions to preserve local electroneutrality. At high salt concentrations (>1 M ) adsorption processes associated to the binding of cations to the channel charges regulate the transport properties.

  18. Recent Developments in Graphene-Based Membranes: Structure, Mass-Transport Mechanism and Potential Applications.

    Science.gov (United States)

    Sun, Pengzhan; Wang, Kunlin; Zhu, Hongwei

    2016-03-01

    Significant achievements have been made on the development of next-generation filtration and separation membranes using graphene materials, as graphene-based membranes can afford numerous novel mass-transport properties that are not possible in state-of-art commercial membranes, making them promising in areas such as membrane separation, water desalination, proton conductors, energy storage and conversion, etc. The latest developments on understanding mass transport through graphene-based membranes, including perfect graphene lattice, nanoporous graphene and graphene oxide membranes are reviewed here in relation to their potential applications. A summary and outlook is further provided on the opportunities and challenges in this arising field. The aspects discussed may enable researchers to better understand the mass-transport mechanism and to optimize the synthesis of graphene-based membranes toward large-scale production for a wide range of applications. PMID:26797529

  19. Transport equations, Level Set and Eulerian mechanics. Application to fluid-structure coupling

    International Nuclear Information System (INIS)

    My works were devoted to numerical analysis of non-linear elliptic-parabolic equations, to neutron transport equation and to the simulation of fabrics draping. More recently I developed an Eulerian method based on a level set formulation of the immersed boundary method to deal with fluid-structure coupling problems arising in bio-mechanics. Some of the more efficient algorithms to solve the neutron transport equation make use of the splitting of the transport operator taking into account its characteristics. In the present work we introduced a new algorithm based on this splitting and an adaptation of minimal residual methods to infinite dimensional case. We present the case where the velocity space is of dimension 1 (slab geometry) and 2 (plane geometry) because the splitting is simpler in the former

  20. Electrical transport mechanisms and structure of hydrogenated and non-hydrogenated nanocrystalline Ga1−xMnxAs films

    International Nuclear Information System (INIS)

    Highlights: • Ga1−xMnxAs films were produced by the RF magnetron sputtering technique. • The structures of the films were analyzed by Rietveld refinement. • Electrical conductivity was analyzed with basis on the structure and morphology. • Space charge limited current regime was identified in the films without manganese. • The electrical transport of the sample with manganese showed only “Ohmic regime”. - Abstract: The mechanisms of electrical conductivity in hydrogenated and non-hydrogenated nanocrystalline Ga1−xMnxAs (0.000 ⩽ x ⩽ 0.081) films were analyzed, first from a macroscopic perspective, followed by microscopic analysis to investigate the energy levels for trapping electric charges. The analysis of the current–voltage and resistivity–temperature characteristics allowed the development of a model based on the morphology and structure of the films. This model takes into account the main aspects of the transport above 300 K. Space charge limited current (SCLC) mechanism was observed in Mn-free films and is associated with deep trap states located at 0.10 and 0.22 eV below the conduction band. In samples containing Mn, the dark conductivity is highly dependent on the presence of hydrogen. This effect was related to the grain boundaries and interstitial regions of the films, in which the density of gap states is expected to be reduced by the presence of hydrogen

  1. Mechanical evaluation of a natural UF6 transport container at high temperature

    International Nuclear Information System (INIS)

    International Atomic Energy Agency (IAEA) revised the transport regulation for natural uranium hexafluoride (UF6) transportation taking into account chemical and radiological hazards in 1996. A supplementary fire test requirement (800 deg. C for 30 minutes) was imposed on the natural UF6 transport container. In 1996, Central Research Institute of Electric Power Industry (CRIEPI) and Nuclear Protection and Safety Institute (IPSN) terminated experimental joint research works with the aim to determine the thermal-physical behavior of UF6 in a transport container under realistic fire conditions and to use the experimental data to validate a thermal-hydraulic numerical model. Now, they have started a new experimental joint research as to the rupture test of the 48Y-cylinder which will be terminated at the end of 1998. The purpose of this study is to evaluate numerically the mechanical integrity of this cylinder in the IAEA fire test conditions. Firstly, pre-thermal-hydraulic numerical analysis of the 48Y-cylinder under the IAEA fire test condition was performed. Nextly, the structural material model at high temperature for natural UF6 transport container was proposed based on the CRIEPI's material tests and applied to the ABAQUS computer code. According to the mechanical non-linear analysis results, it was found that it is necessary to evaluate the safety margin for the rupture of the 48Y-cylinder because considerable plastic and creep deformations are generated due to the temperature distribution of the cylinder and the inner pressure. This thermal-mechanical behavior of the container will be verified according to the rupture test results of the 48Y-cylinder until the end of 1998. (authors)

  2. Experiment showing a mechanical manifestation of the helicity of transport current in superconducting wires

    International Nuclear Information System (INIS)

    The transport current density of the mixed state of type II wires will have the form J = z J/sub z/ + THETA J/sub THETA/ when the supercurrent exhibits a helical distribution due to the application of an external field H/sub z/. This is proved by the magnetic moment measurements of Walmsley and Timms, who observed the so-called paramagnetic component of moment M when J/sub THETA/ not equal to 0. A mechanical manifestation of the helical current was observed by combining a normal-zone propagation experiment with a capacitive technique for measuring mechanical torsion of the sample. Moreover, the torsion was observed even when H/sub z/ = 0, an effect that might be explained by the theory of Kondo and Kuroda on the helicity of transport currents in normal metals due to spiral dislocations

  3. The molecular mechanism of Zinc acquisition by the neisserial outer-membrane transporter ZnuD

    Science.gov (United States)

    Calmettes, Charles; Ing, Christopher; Buckwalter, Carolyn M.; El Bakkouri, Majida; Chieh-Lin Lai, Christine; Pogoutse, Anastassia; Gray-Owen, Scott D.; Pomès, Régis; Moraes, Trevor F.

    2015-08-01

    Invading bacteria from the Neisseriaceae, Acinetobacteriaceae, Bordetellaceae and Moraxellaceae families express the conserved outer-membrane zinc transporter zinc-uptake component D (ZnuD) to overcome nutritional restriction imposed by the host organism during infection. Here we demonstrate that ZnuD is required for efficient systemic infections by the causative agent of bacterial meningitis, Neisseria meningitidis, in a mouse model. We also combine X-ray crystallography and molecular dynamics simulations to gain insight into the mechanism of zinc recognition and transport across the bacterial outer-membrane by ZnuD. Because ZnuD is also considered a promising vaccine candidate against N. meningitidis, we use several ZnuD structural intermediates to map potential antigenic epitopes, and propose a mechanism by which ZnuD can maintain high sequence conservation yet avoid immune recognition by altering the conformation of surface-exposed loops.

  4. Fracture mechanics based design for radioactive material transport packagings -- Historical review

    International Nuclear Information System (INIS)

    The use of a fracture mechanics based design for the radioactive material transport (RAM) packagings has been the subject of extensive research for more than a decade. Sandia National Laboratories (SNL) has played an important role in the research and development of the application of this technology. Ductile iron has been internationally accepted as an exemplary material for the demonstration of a fracture mechanics based method of RAM packaging design and therefore is the subject of a large portion of the research discussed in this report. SNL's extensive research and development program, funded primarily by the U. S. Department of Energy's Office of Transportation, Energy Management and Analytical Services (EM-76) and in an auxiliary capacity, the office of Civilian Radioactive Waste Management, is summarized in this document along with a summary of the research conducted at other institutions throughout the world. In addition to the research and development work, code and standards development and regulatory positions are also discussed

  5. Drug transport mechanism of P-glycoprotein monitored by single molecule fluorescence resonance energy transfer

    CERN Document Server

    Ernst, Stefan; Zarrabi, Nawid; Wilkens, Stephan; Boersch, Michael

    2011-01-01

    In this work we monitor the catalytic mechanism of P-glycoprotein (Pgp) using single-molecule fluorescence resonance energy transfer (FRET). Pgp, a member of the ATP binding cassette family of transport proteins, is found in the plasma membrane of animal cells where it is involved in the ATP hydrolysis driven export of hydrophobic molecules. When expressed in the plasma membrane of cancer cells, the transport activity of Pgp can lead to the failure of chemotherapy by excluding the mostly hydrophobic drugs from the interior of the cell. Despite ongoing effort, the catalytic mechanism by which Pgp couples MgATP binding and hydrolysis to translocation of drug molecules across the lipid bilayer is poorly understood. Using site directed mutagenesis, we have introduced cysteine residues for fluorescence labeling into different regions of the nucleotide binding domains (NBDs) of Pgp. Double-labeled single Pgp molecules showed fluctuating FRET efficiencies during drug stimulated ATP hydrolysis suggesting that the NBD...

  6. Charge transport mechanisms of graphene/semiconductor Schottky barriers: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Haijian; Liu, Zhenghui; Xu, Gengzhao; Shi, Lin; Fan, Yingmin; Yang, Hui [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Xu, Ke, E-mail: kxu2006@sinano.ac.cn; Wang, Jianfeng; Ren, Guoqiang [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Suzhou Nanowin Science and Technology Co., Ltd., Suzhou 215123 (China)

    2014-01-07

    Graphene has been proposed as a material for semiconductor electronic and optoelectronic devices. Understanding the charge transport mechanisms of graphene/semiconductor Schottky barriers will be crucial for future applications. Here, we report a theoretical model to describe the transport mechanisms at the interface of graphene and semiconductors based on conventional semiconductor Schottky theory and a floating Fermi level of graphene. The contact barrier heights can be estimated through this model and be close to the values obtained from the experiments, which are lower than those of the metal/semiconductor contacts. A detailed analysis reveals that the barrier heights are as the function of the interface separations and dielectric constants, and are influenced by the interfacial states of semiconductors. Our calculations show how this behavior of lowering barrier heights arises from the Fermi level shift of graphene induced by the charge transfer owing to the unique linear electronic structure.

  7. The application of fracture mechanics to the safety assessment of transport casks for radioactive materials

    International Nuclear Information System (INIS)

    BAM is the German responsible authority for the mechanical and thermal design safety assessment of packages for the transport of radioactive materials. The assessment has to cover the brittle fracture safety proof of package components made of potentially brittle materials. This paper gives a survey of the regulatory and technical requirements for such an assessment according to BAM's new ''Guidelines for the Application of Ductile Cast Iron for Transport and Storage Casks for Radioactive Materials''. Based on these guidelines higher stresses than before can become permissible, but it is necessary to put more effort into the safety assessment procedure. The fundamentals of such a proof with the help of the methods of fracture mechanics are presented. The recommended procedure takes into account the guidelines of the IAEA Advisory Material which are based on the prevention of crack initiation. Examples of BAM's research and safety assessment practices are given. Recommendations for further developments towards package designs with higher acceptable stress levels will be concluded

  8. Electronic transport and mechanical properties of phosphorus and phosphorus-nitrogen doped carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Sumpter, Bobby G [ORNL; Charlier, Jean Christophe [Universite Catholique de Louvain; Terrones Maldonado, Mauricio [ORNL; Meunier, Vincent [ORNL; Terrones Maldonado, Humberto [ORNL; Cruz Silva, Eduardo [ORNL; Lopez, Florentino [IPICyT; Munoz-Sandoval, Emilio [IPICyT

    2009-01-01

    We present a density functional theory study of the electronic structure, quantum transport and mechanical properties of recently synthesized phosphorus (P) and phosphorus-nitrogen (PN) doped single-walled carbon nanotubes. The results demonstrate that substitutional P and PN doping creates localized electronic states that modify the electron transport properties by acting as scattering centers. For low doping concentrations (1 doping site per ~200 atoms), the quantum conductance for metallic nanotubes is found to be only slightly reduced. The substitutional doping also alters the mechanical strength, leading to a 50% reduction in the elongation upon fracture, while Young s modulus remains approximately unchanged. Overall, the PN- and P-doped nanotubes display promising properties for components in composite materials and, in particular, for fast response and ultra sensitive sensors operating at the molecular level.

  9. Endosomal Transport of ErbB-2: Mechanism for Nuclear Entry of the Cell Surface Receptor†

    OpenAIRE

    Giri, Dipak K.; Ali-Seyed, Mohamed; Li, Long-Yuan; Lee, Dung-Fang; Ling, Pin; Bartholomeusz, Geoffrey; Wang, Shao-chun; Hung, Mien-Chie

    2005-01-01

    The cell membrane receptor ErbB-2 migrates to the nucleus. However, the mechanism of its nuclear translocation is unclear. Here, we report a novel mechanism of its nuclear localization that involves interaction with the transport receptor importin β1, nuclear pore protein Nup358, and a host of players in endocytic internalization. Knocking down importin β1 using small interfering RNA oligonucleotides or inactivation of small GTPase Ran by RanQ69L, a dominant-negative mutant of Ran, causes a n...

  10. Charge-carrier transport mechanisms in composites containing carbon-nanotube inclusions

    Energy Technology Data Exchange (ETDEWEB)

    Usanov, D. A., E-mail: UsanovDA@info.sgu.ru; Skripal’, A. V.; Romanov, A. V. [Saratov State University (Russian Federation)

    2015-12-15

    From the microwave-radiation transmittance and reflectance spectra, the temperature dependence of the complex permittivity of carbon nanotubes, subjected to high-temperature annealing, and composite materials produced on their basis is determined. The electron transport mechanisms in composites with inclusions of unannealed carbon nanotubes and nanotubes subjected to high-temperature annealing are determined. The influence of the annealing temperature on the parameters that are characteristic of these mechanisms and control the temperature dependence of the conductivity of multiwall carbon nanotubes is established.

  11. Charge-carrier transport mechanisms in composites containing carbon-nanotube inclusions

    International Nuclear Information System (INIS)

    From the microwave-radiation transmittance and reflectance spectra, the temperature dependence of the complex permittivity of carbon nanotubes, subjected to high-temperature annealing, and composite materials produced on their basis is determined. The electron transport mechanisms in composites with inclusions of unannealed carbon nanotubes and nanotubes subjected to high-temperature annealing are determined. The influence of the annealing temperature on the parameters that are characteristic of these mechanisms and control the temperature dependence of the conductivity of multiwall carbon nanotubes is established

  12. Investigations of particle transport mechanism during a blowdown test at the HDR

    International Nuclear Information System (INIS)

    Experiments have been performed in the HDR-Containment focussed on transport mechanism of solid particles after a loss of coolant accident. For this purpose at several locations marked particles of various size have been deposed before a LOCA-experiment and their distribution after the experiment investigated. The complex geometry of the HDR-Containment has many floors for deposition of solid particles, so no particles were drained to the containment sump. (orig.)

  13. Mechanism of hypercalciuria in genetic hypercalciuric rats. Inherited defect in intestinal calcium transport.

    OpenAIRE

    Bushinsky, D A; Favus, M J

    1988-01-01

    Excessive urine calcium excretion in patients with idiopathic hypercalciuria may involve a primary increase in intestinal calcium absorption, overproduction of 1,25-dihydroxyvitamin D3 or a defect in renal tubular calcium reabsorption. To determine the mechanism of hypercalciuria in an animal model, hypercalciuria was selected for in rats and the most hypercalciuric animals inbred. Animals from the fourth generation were utilized to study mineral balance and intestinal transport in relation t...

  14. Analysis of Mechanical Energy Transport on Free-Falling Wedge during Water-Entry Phase

    OpenAIRE

    Yan-Ying Wang; Wen-Hua Wang; Yi Huang

    2012-01-01

    For better discussing and understanding the physical phenomena and body-fluid interaction of water-entry problem, here mechanical-energy transport (wedge, fluid, and each other) of water-entry model for free falling wedge is studied by numerical method based on free surface capturing method and Cartesian cut cell mesh. In this method, incompressible Euler equations for a variable density fluid are numerically calculated by the finite volume method. Then artificial compressibility method, dual...

  15. Interaction of gatifloxacin with efflux transporters: a possible mechanism for drug resistance

    OpenAIRE

    Kwatra, Deep; Vadlapatla, Ramya Krishna; Vadlapudi, Aswani Dutt; Pal, Dhananjay; Mitra, Ashim K

    2010-01-01

    The purpose of the study is to screen the interactions of fourth generation fluoroquinolone-gatifloxacin with efflux pumps i.e. P-gp, MRP2 and BCRP. Mechanism of gatifloxacin interaction with efflux transporters may explain its acquired resistance. Such clarification may lead to the development of strategies to overcome efflux and enhance its bioavailability at target site. This process will aid in the reduction of dose volume, further eliminating the chances of systemic toxicity from topical...

  16. The influence of the membrane transport on the heart mechanical activity

    Czech Academy of Sciences Publication Activity Database

    Převorovská, Světlana; Maršík, František

    Vol. 2. Brno : VUT, 1999 - (Kratochvíl, C.; Kotek, V.; Krejsa, J.), s. 55-60 ISBN 80-214-1325-5. [International conference Engineering mechanics '99.. Svratka (CZ), 17.05.1999-20.05.1999] R&D Projects: GA ČR GA106/98/1373 Grant ostatní: PP ÚT AV ČR(XC) 2/50 U Keywords : human cardiovascular system * myocardium * membrane transport Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  17. Reform of refined oil product pricing mechanism and energy rebound effect for passenger transportation in China

    International Nuclear Information System (INIS)

    Improving energy efficiency is the primary method adopted by the Chinese government in an effort to achieve energy conservation target in the transport sector. However, the offsetting effect of energy rebound would greatly reduce its real energy-saving potentials. We set up a Linear Approximation of the Almost Ideal Demand System Model (LA-AIDS model) to estimate the rebound effect for passenger transportation in China. Real energy conservation effect of improving energy efficiency can also be obtained in the process. The result shows that the rebound effect is approximately 107.2%. This figure signifies the existence of ‘backfire effect’, indicating that efficiency improvement in practice does not always lead to energy-saving. We conclude that one important factor leading to the rebound effect, is the refined oil pricing mechanism. China's refined oil pricing mechanism has been subjected to criticism in recent years. The results of simulation analysis show that the rebound could be reduced to approximately 90.7% if the refined oil pricing mechanism is reformed. In this regard, we suggest further reforms in the current refined oil pricing mechanism. - Highlights: ► We set up the LA-AIDS model to estimate traffic service demand for urban residents. ► The size of the rebound effect for passenger transportation in China is evaluated. ► The rebound effect for passenger transportation in China is 107.2%. ► Reform of oil pricing could reduced the rebound to 90.7%. ► Reform of oil pricing might be an effective method for mitigating rebound effect

  18. A Novel Mechanism for Fire Detection in Subway Transportation Systems Based on Wireless Sensor Networks

    OpenAIRE

    Zhen-Jiang Zhang; Jun-Song Fu; Hua-Pei Chiang; Yueh-Min Huang

    2013-01-01

    Fire is a common and disastrous phenomenon in subway transportation systems because of closed environment and large passenger flow. Traditional methods detect and forecast fire incidents by fusing the data collected by wireless sensor networks and compare the fusion result with a threshold. However, this approach has a significant shortcoming. Fusion of data decreases the amount of useful information since the distribution of data is not considered. In this paper, a novel mechanism based on w...

  19. Molecular mechanisms of cocaine reward: Combined dopamine and serotonin transporter knockouts eliminate cocaine place preference

    OpenAIRE

    Sora, Ichiro; Hall, F. Scott; Andrews, Anne M.; Itokawa, Masanari; Li, Xiao-Fei; Wei, Hong-Bing; Wichems, Christine; Lesch, Klaus-Peter; Murphy, Dennis L.; Uhl, George R

    2001-01-01

    Cocaine blocks uptake by neuronal plasma membrane transporters for dopamine (DAT), serotonin (SERT), and norepinephrine (NET). Cocaine reward/reinforcement has been linked to actions at DAT or to blockade of SERT. However, knockouts of neither DAT, SERT, or NET reduce cocaine reward/reinforcement, leaving substantial uncertainty about cocaine's molecular mechanisms for reward. Conceivably, the molecular bases of cocaine reward might display sufficient redundancy th...

  20. Zinc Transporters, Mechanisms of Action and Therapeutic Utility: Implications for Type 2 Diabetes Mellitus

    OpenAIRE

    Myers, Stephen A.; Alex Nield; Mark Myers

    2012-01-01

    Zinc is an essential trace element that plays a vital role in maintaining many biological processes and cellular homeostasis. Dysfunctional zinc signaling is associated with a number of chronic disease states including cancer, cardiovascular disease, Alzheimers disease, and diabetes. Cellular homeostasis requires mechanisms that tightly control the uptake, storage, and distribution of zinc. This is achieved through the coordinated actions of zinc transporters and metallothioneins. Evidence o...

  1. Buoyancy-driven flow in a peat moss layer as a mechanism for solute transport.

    Science.gov (United States)

    Rappoldt, Cornelis; Pieters, Gert-Jan J M; Adema, Erwin B; Baaijens, Gerrit J; Grootjans, Ab P; van Duijn, Cornelis J

    2003-12-01

    Transport of nutrients, CO2, methane, and oxygen plays an important ecological role at the surface of wetland ecosystems. A possibly important transport mechanism in a water-saturated peat moss layer (usually Sphagnum cuspidatum) is nocturnal buoyancy flow, the downward flow of relatively cold surface water, and the upward flow of warm water induced by nocturnal cooling. Mathematical stability analysis showed that buoyancy flow occurs in a cooling porous layer if the system's Rayleigh number (Ra) exceeds 25. For a temperature difference of 10 K between day and night, a typical Ra value for a peat moss layer is 80, which leads to quickly developing buoyancy cells. Numerical simulation demonstrated that fluid flow leads to a considerable mixing of water. Temperature measurements in a cylindrical peat sample of 50-cm height and 35-cm diameter were in agreement with the theoretical results. The nocturnal flow and the associated mixing of the water represent a mechanism for solute transport in water-saturated parts of peat land and in other types of terrestrializing vegetation. This mechanism may be particularly important in continental wetlands, where Ra values in summer are often much larger than the threshold for fluid flow. PMID:14657381

  2. Analog performance of vertical nanowire TFETs as a function of temperature and transport mechanism

    Science.gov (United States)

    Martino, Marcio Dalla Valle; Neves, Felipe; Ghedini Der Agopian, Paula; Martino, João Antonio; Vandooren, Anne; Rooyackers, Rita; Simoen, Eddy; Thean, Aaron; Claeys, Cor

    2015-10-01

    The goal of this work is to study the analog performance of tunnel field effect transistors (TFETs) and its susceptibility to temperature variation and to different dominant transport mechanisms. The experimental input characteristic of nanowire TFETs with different source compositions (100% Si and Si1-xGex) has been presented, leading to the extraction of the Activation Energy for each bias condition. These first results have been connected to the prevailing transport mechanism for each configuration, namely band-to-band tunneling (BTBT) or trap assisted tunneling (TAT). Afterward, this work analyzes the analog behavior, with the intrinsic voltage gain calculated in terms of Early voltage, transistor efficiency, transconductance and output conductance. Comparing the results for devices with different source compositions, it is interesting to note how the analog trends vary depending on the source characteristics and the prevailing transport mechanisms. This behavior results in a different suitability analysis depending on the working temperature. In other words, devices with full-Silicon source and non-abrupt junction profile present the worst intrinsic voltage gain at room temperature, but the best results for high temperatures. This was possible since, among the 4 studied devices, this configuration was the only one with a positive intrinsic voltage gain dependence on the temperature variation.

  3. Mechanical and transport characteristic exploration for coated conductors by hoop stress tests

    International Nuclear Information System (INIS)

    Mechanical and transport characteristics of coated conductors were explored by hoop stress tests at 4.2 K, 11 T. Deformation was investigated by strain gauges. Monolayer coils were simple, i.e. BJR-strain relations were observed. The first observation of radial deformation of a multilayer coil fabricated by YBCO coated conductor. The authors have explored mechanical and transport characteristics of coated conductors by hoop stress tests at 4.2 K, 11 T. Two monolayer coils, which were YBa2Cu3O7 (YBCO) and GdBa2Cu3O7 (GdBCO) coils, and a double-stacked single-pancake coil were tested. The mechanical and electrical behavior of monolayer coils were simple, thus they were well explained by simple forms. The stress and strain were easily evaluated by using BJR relation and strain gauge measurements. On the other hand, the behavior of the pancake coil was not simple. The analytically evaluated azimuthal strain was qualitatively consistent with measured strain. However, the measured radial strain was not explained by analytically because of non-monolithic deformation of the coil. The transport characteristic was influenced by the non-monolithic deformation.

  4. Delivery of marine larvae to shore requires multiple sequential transport mechanisms.

    Science.gov (United States)

    Pfaff, Maya C; Branch, George M; Fisher, Jennifer L; Hoffmann, Vera; Ellis, Allan G; Largier, John L

    2015-05-01

    Most sedentary marine animals disperse from their place of origin during their initial life stages as larvae. The delivery of planktonic larvae back to coastal adult habitats after weeks or months of offshore development is commonly thought to be stochastic, resulting in large recruitment fluctuations and making predictive understanding of population dynamics difficult. Time series of invertebrate settlement on intertidal shores have been used to infer how various oceanographic processes deliver planktonic larvae ashore. However, the possibility that successful settlement may involve a series of different transport mechanisms, which are sequentially utilized by late-stage larvae, has received little attention. To address this, we monitored both the delivery of mussel and barnacle larvae to inner-shelf moorings positioned 200-1400 m from the shore, and larval settlement in the intertidal adult habitat, at two contrasting sites: a headland forming an upwelling center and a downstream bay. Model selection was employed to determine the most likely scenario(s) of larval onshore transport from four a priori transport mechanisms individually and in combination: (1) upwelling or relaxation/downwelling, (2) tidal motions, (3) diurnal sea breezes, and (4) surface waves. Mussel larvae were delivered to the inner shelf during upwelling in the bay, but during downwelling at the headland, and were further transported to the shore by surface waves at both locales. In contrast, the delivery of barnacle larvae to the inner shelf occurred during relaxation/downwelling events at both sites, and intertidal settlement coincided with spring tides, suggesting a role for internal tides in their onshore transport. Thus, sequential mechanisms appear to be utilized by larvae to get to the shore, involving interactions of regional-scale upwelling/downwelling processes and local-scale tidal and surface-wave processes, which differ among taxa and among sites with different topography. A bottleneck for larval delivery across the surf zone may be a result of out-of-phase steps in sequential transport mechanisms leaving larvae lost "in transit." PMID:26236852

  5. Fibre bundle formulation of nonrelativistic quantum mechanics: I. Introduction. The evolution transport

    International Nuclear Information System (INIS)

    We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one and is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it the Hilbert space of a quantum system (from conventional quantum mechanics) is replaced with an appropriate Hilbert bundle of states and a pure state of the system is described by a lifting of paths or sections along paths in this bundle. The evolution of a pure state is determined through the bundle (analogue of the) Schroedinger equation. Now the dynamical variables and density operators are described via liftings of paths or morphisms along paths in suitable bundles. The mentioned quantities are connected by a number of relations derived in this paper. The present, first, part of this investigation is devoted to the introduction of basic concepts on which the fibre bundle approach to quantum mechanics rests. We show that the evolution of pure quantum mechanical states can be described as a suitable linear transport along paths, called evolution transport, of the state liftings in the Hilbert bundle of states of a considered quantum system. (author)

  6. Charge transport mechanisms in organic and microcrystalline silicon field-effect transistors

    Science.gov (United States)

    Konezny, S. J.; Bussac, M. N.; Geiser, A.; Zuppiroli, L.

    2007-09-01

    Several organic and inorganic materials have emerged as promising candidates for the active layer of field-effect transistors (FETs) fabricated on flexible substrates. The charge transport models necessary for device optimization in these systems are at different stages of development. The understanding of charge transport in single-crystal and thin-film FETs based on organic materials such as pentacene, rubrene, and other related compounds has advanced considerably in recent years and a clear picture of the relevant transport mechanisms is forming. In contrast, the theoretical description of transport in hydrogenated microcrystalline silicon (μc-Si:H) is not as well known and the published results and theories are often contradictory. We review the paradigms we feel are useful in describing the current understanding of transport in organic and μc-Si:H field-effect transistors. In the case of organic materials these include the polarization and transfer integral fluctuation model [A. Troisi and G. Orlandi, Phys. Rev. Lett. 96, 086601 (2006), J.-D. Picon et al., Phys. Rev. B 75, 235106 (2007)], the Frölich polaron model [I.N. Hulea et al., Nat. Mater. 5, 982 (2006), H. Houilli et al., J. Appl. Phys. 100, 033702 (2006)], and several trapping models [M.E. Gershenson et al., Rev. Mod. Phys. 78, 973 (2006), V. Podzorov et al., Phys Rev. Lett. 95, 226601 (2005)]. Given the heterogeneous composition and structure of microcrystalline silicon thin films, a variety of theories to describe dark conductivity have been applied to μc-Si:H including those based on percolation theory [H. Overhof et al., J. Non-Cryst. Solids 227-230, 992 (1998)], hopping models [A. Dussan and R. H. Buitrago, J. Appl. Phys. 97, 043711 (2005)], thermionic emission, and tunneling. We give a brief overview of these models and present a fluctuation-induced tunneling model that we are developing to describe charge transport in microcrystalline silicon.

  7. MAINE AQUIFERS

    Science.gov (United States)

    AQFRS24 contains polygons of significant aquifers in Maine (glacial deposits that are a significant ground water resource) mapped at a scale 1:24,000. This statewide coverage was derived from aquifer boundaries delineated and digitized by the Maine Geological Survey from data com...

  8. Discovery of a Biological Mechanism of Active Transport through the Tympanic Membrane to the Middle Ear.

    Science.gov (United States)

    Kurabi, Arwa; Pak, Kwang K; Bernhardt, Marlen; Baird, Andrew; Ryan, Allen F

    2016-01-01

    Otitis media (OM) is a common pediatric disease for which systemic antibiotics are often prescribed. While local treatment would avoid the systemic treatment side-effects, the tympanic membrane (TM) represents an impenetrable barrier unless surgically breached. We hypothesized that the TM might harbor innate biological mechanisms that could mediate trans-TM transport. We used two M13-bacteriophage display biopanning strategies to search for mediators of trans-TM transport. First, aliquots of linear phage library displaying 10(10th) 12mer peptides were applied on the TM of rats with active bacterial OM. The middle ear (ME) contents were then harvested, amplified and the preparation re-applied for additional rounds. Second, the same naïve library was sequentially screened for phage exhibiting TM binding, internalization and then transit. Results revealed a novel set of peptides that transit across the TM to the ME in a time and temperature dependent manner. The peptides with highest transport capacities shared sequence similarities. Historically, the TM was viewed as an impermeable barrier. However, our studies reveal that it is possible to translocate peptide-linked small particles across the TM. This is the first comprehensive biopanning for the isolation of TM transiting peptidic ligands. The identified mechanism offers a new drug delivery platform into the ME. PMID:26946957

  9. Current transport mechanism and effect of hydrogen plasma treatment on Al-GaSb Schottky diode

    International Nuclear Information System (INIS)

    The aluminium Schottky contact to n-GaSb was fabricated using standard photolithography and lift-off techniques. The ohmic contact of low resistance was first formed by evaporating Ge-Au-Ni-Au (88% Au - 12% Ge by weight) on GaSb surface then followed by heat treatments. The I-V-T measurements were performed with a cryogenic system. The current transport mechanism of this non-ideal Al-GaSb Schottky diode was modelled for a wide temperature range. The conduction in both ? and L valleys was included in the calculation of the thermionic emission current component. The contribution of thermionic emission, recombination and other current transport mechanisms were evaluated. The I-V characteristic at 300 K had an ideality factor of about 2 since the recombination dominates the current transport. However, at higher temperatures the thermionic emission becomes important and the ideality factor decreases below 2. We also examined the electrical properties of this diode after exposure on hydrogen plasma

  10. Coupled mechanical and chemo-transport model for the simulation of cementitious materials subjected to external sulfate attack

    International Nuclear Information System (INIS)

    We propose in this study to develop a chemo-transport-mechanical model for the simulation of external sulfate attack in cementitious materials. This degradation mainly consists in the hydrate decalcification/dissolution due to leaching, and in the reaction between the sulfate ions migrating within the material and mono-sulfate initially present to precipitate into ettringite. It may generate macroscopic expansions leading to severe microcracking. The key point in this study is the use of the integration numerical platform ALLIANCES which couples a code solving the chemical equations, the diffusion of ionic species into the porosity and the mechanical problem. The crystallization pressures resulting from the interaction between growing mono-sulfate crystals and the surrounding C-S-H matrix are assumed to cause the observed macroscopic swelling. A macroscopic bulk strain tensor calculated from the volume of formed ettringite is introduced for directly reproducing these expansions. Explicit up-scaling techniques applied on a simplified representation of the materials allow estimating both mechanical and diffusive properties of the evolving microstructure. The calculated macroscopic free expansions are in quite good agreement with experimental data, provided a correct calibration of the parameter involved in the expression of the bulk strain tensor. However, it is asserted that the model would lead to very high stress levels in the structures in the particular case of restrained displacements at its boundaries

  11. Air pollutants and plant cuticles: mechanisms of gas and water transport, and effects on water permeability

    International Nuclear Information System (INIS)

    A short overview of studies carried out by K.J. Lendzian and his group on transport rates of pure pollutant gases across isolated cuticles will be given. They show that the boiling point of a gas is a good predictor of cuticular permeability. Apparently good prediction quality, however, contrasts with a considerable gap between uptake rates determined in stomata-free systems, and rates of dry deposition to whole leaves observed under conditions where stomata should be closed to the maximum extent. Apart from other possible reasons for this difference, examination of cuticular sorption and diffusion characteristics indicates two major problems that may account for inconsistencies to some extent: (1) transport rates of gases in cuticles may be concentration-dependent and (2) interactions in gas mixtures with respect to cuticular transport are possible. Potential mechanisms of transport across cuticles and ways of interaction between gases (including water vapour) will be discussed. There has long been the notion that air pollutants may affect the water barrier quality of plant cuticles. This hypothesis has been tested in a recent study of effects of a wide range of air pollutants and elevated UV-B radiation on adaxial in situ-cuticular water permeability of various broadleaf tree species. No effects were found unless the leaves showed visible signs of stress due to treatment or chamber effects. (orig.)

  12. The mechanical design for the second axis beam transport line for the DARHT facility

    International Nuclear Information System (INIS)

    This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) facility. The DARHT II project is a collaboration between LANL, LBNL, and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-ampersand micro;sec pulse length linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The downstream beam transport line is an 18-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 17 conventional solenoid, quadrupole and dipole magnets; as well as several specialty magnets, which transport and focus the beam to the target and beam dumps. There is a high power beam dump, which is designed to absorb the 80-kJ of beam energy during accelerator start-up and operation. The beamline vacuum chamber has an 8-cm diameter aperture and operates at an average pressure of 10-7 Torr

  13. How do we convert the transport sector to renewable energy and improve the sector's interplay with the energy system? Main findings and recommendations from Workshop on Transport - renewable energy in the transport sector and planning

    Energy Technology Data Exchange (ETDEWEB)

    Soenderberg Petersen, L.; Larsen, Hans (eds.)

    2009-07-15

    As part of the DTU Climate Change Technologies Programme, DTU arranged a series of workshops and conferences on climate change technology focusing on assessment of and adaptation to climate changes as well as on mitigation of greenhouse gasses (GHG). Each workshop targeted a specific technology problem area. The Workshop on Transport took place at DTU 17 - 18 March 2009. The workshop developed and discussed recommendations for future climate change technologies. This report presents summary and recommendations from the workshop. (au)

  14. spatial variability of solute transport mechanisms based on time domain reflectometry and generalized transfer function model

    International Nuclear Information System (INIS)

    the flexible generalized transfer function model (GTF ) and TDR based time normalized resident concentrations were combined in order to characterize solute transport mechanism both at local and field scale. a leaching experiment was carried out in a plot under greenhouse, where TDR probes were installed at the three different depths at 37 sites along a 40 m transect. the field plot was brought to steady-state water content; a pulse application of 3.87 mm of KCl solution was applied . measurements of water content (?) and impedance (Z) were simultaneously taken to follow the kcl solution propagation through the soil profile. time series of relative resident concentrations for each site where effectively interpreted in terms of GTF model. the field scale behavior was described by calculating a local average and an integral average, by averaging local scale parameters and local scale original measurements, respectively. the two different averaging schemes resulted in two significantly different field scale solute transport behaviors

  15. Growth Dynamics and Gas Transport Mechanism of Nanobubbles in Graphene Liquid Cells

    CERN Document Server

    Shin, Dongha; Kim, Yong-Jin; Kim, Sang Jin; Kang, Jin Hyoun; Lee, Bora; Cho, Sung-Pyo; Hong, Byung Hee; Novoselov, Konstantin S

    2014-01-01

    Formation, evolution, and vanishing of bubbles are common phenomena in our nature, which can be easily observed in boiling or falling waters, carbonated drinks, gas-forming electrochemical reactions, etc. However, the morphology and the growth dynamics of the bubbles at nanoscale have not been fully investigated owing to the lack of proper imaging tools that can visualize nanoscale objects in liquid phase. Here we demonstrate, for the first time, that the nanobubbles in water encapsulated by graphene membrane can be visualized by in situ ultrahigh vacuum transmission electron microscopy (UHV-TEM), showing the critical radius of nanobubbles determining its unusual long-term stability as well as two distinct growth mechanisms of merging nanobubbles (Ostwald ripening and coalescing) depending on their relative sizes. Interestingly, the gas transport through ultrathin water membranes at nanobubble interface is free from dissolution, which is clearly different from conventional gas transport that includes condensa...

  16. Mechanisms of heat transport across a nano-scale gap in heat assisted magnetic recording

    Science.gov (United States)

    Budaev, Bair V.; Bogy, David B.

    2012-06-01

    This paper compares different mechanisms of heat transport across nano-scale gaps and discusses the role of electromagnetic phenomena in heat transport in general nano-scale layered structures. The results of the analysis suggest that heat transfer across sub-5 nm gaps like that appearing in prototypes of heat assisted magnetic recording (HAMR) systems is dominated by direct intermolecular interactions between the separated bodies and is little affected by electromagnetic radiation. The analysis further suggests that local heating for HAMR with sub-5 nm spacing can be more efficiently achieved by a Joule heater that is simpler to fabricate than laser-based optical systems and is less destructive for the nano-scale transducers than laser radiation, which may lead to their structural damage and short duration life of nanoscale transducers.

  17. Investigation of MCHM transport mechanisms and fate: implications for coal beneficiation.

    Science.gov (United States)

    He, Y Thomas; Noble, Aaron; Ziemkiewicz, Paul

    2015-05-01

    4-Methyl cyclohexane methanol (MCHM) is a flotation reagent often used in fine coal beneficiation and notably involved in the January 9, 2014 Elk River chemical spill in Charleston, WV. This study investigates the mechanisms controlling the transport and fate of MCHM in coal beneficiation plants and surrounding environments. Processes such as volatilization, sorption, and leaching were evaluated through laboratory batch and column experiments. The results indicate volatilization and sorption are important mechanisms which influence the removal of MCHM from water, with sorption being the most significant removal mechanism over short time scales (leaching experiments show both coal and tailings have high affinity for MCHM, and this reagent does not desorb readily. Overall, the results from these experiments indicate that MCHM is either volatilized or sorbed during coal beneficiation, and it is not likely to transport out of coal beneficiation plant. Thus, use of MCHM in coal beneficiation plant is not likely to pose threat to either surface or groundwater under normal operating conditions. PMID:25698101

  18. Vitamin A Transport Mechanism of the Multitransmembrane Cell-Surface Receptor STRA6

    Directory of Open Access Journals (Sweden)

    Riki Kawaguchi

    2015-08-01

    Full Text Available Vitamin A has biological functions as diverse as sensing light for vision, regulating stem cell differentiation, maintaining epithelial integrity, promoting immune competency, regulating learning and memory, and acting as a key developmental morphogen. Vitamin A derivatives have also been used in treating human diseases. If vitamin A is considered a drug that everyone needs to take to survive, evolution has come up with a natural drug delivery system that combines sustained release with precise and controlled delivery to the cells or tissues that depend on it. This “drug delivery system” is mediated by plasma retinol binding protein (RBP, the principle and specific vitamin A carrier protein in the blood, and STRA6, the cell-surface receptor for RBP that mediates cellular vitamin A uptake. The mechanism by which the RBP receptor absorbs vitamin A from the blood is distinct from other known cellular uptake mechanisms. This review summarizes recent progress in elucidating the fundamental molecular mechanism mediated by the RBP receptor and multiple newly discovered catalytic activities of this receptor, and compares this transport system with retinoid transport independent of RBP/STRA6. How to target this new type of transmembrane receptor using small molecules in treating diseases is also discussed.

  19. In situ investigation of the mechanisms of the transport to tissues of polycyclic aromatic hydrocarbons adsorbed onto the root surface of Kandelia obovata seedlings.

    Science.gov (United States)

    Li, Ruilong; Zhu, Yaxian; Zhang, Yong

    2015-06-01

    A novel method for in situ determination of the polycyclic aromatic hydrocarbons (PAHs) adsorbed onto the root surface of Kandelia obovata seedlings was established using laser-induced time-resolved nanosecond fluorescence spectroscopy (LITRF). The linear dynamic ranges for the established method were 1.5-1240ng/spot for phenanthrene, 1.0-1360ng/spot for pyrene and 5.0-1220ng/spot for benzo[a]pyrene. Then, the mechanisms of PAHs transport from the Ko root surface to tissues were investigated. The three-phase model including fast, slow and very slow fractions was superior to the single or dual-phase model to describe the PAHs transport processes. Moreover, the fast fraction of PAHs transport process was mainly due to passive movement, while the slow and very slow fractions were not. Passive movement was the main process of B[a]P adsorbed onto Ko root surface transport to tissues. In addition, the extent of the PAHs transport to Ko root tissues at different salinity were evaluated. PMID:25779208

  20. Main Facilities

    International Nuclear Information System (INIS)

    This chapter discuss on main nuclear facilities available in the Malaysian Institute for Nuclear Technology Research (MINT). As a national research institute whose core activities are nuclear science and technology, MINT are made up of main commercializable radiation irradiators, pilot plant and fully equipped laboratories. Well elaboration on its characteristics and functions explain for RTP (PUPSPATI TRIGA reactors), Cobalt-60 gamma irradiator, electron beam accelerators, and radioactive waste management center

  1. Dual mechanism for stimulation of glutamate transport by potassium ions in Streptococcus mutans.

    OpenAIRE

    Y. Sato; Noji, S.; Suzuki, R.; Taniguchi, S

    1989-01-01

    An ATP-driven primary transport system operative for L-glutamate or L-aspartate in Streptococcus mutans is, through the entire pH range from 5.5 to 8.5, specifically stimulated by extracellular potassium ions. The stimulation by potassium ions observed in the low pH range between 5.5 and 7 has been interpreted to be due to potassium ion-dependent regulation of the intracellular pH (the first mechanism). In the high pH range from 7 to 8.5, on the other hand, the present study demonstrates that...

  2. Mechanical, electronic, and transport properties of functionalized graphene monolayers from ab initio studies

    International Nuclear Information System (INIS)

    We present exemplary results of extensive studies of mechanical, electronic and transport properties of covalent functionalization of graphene monolayers (GML). We report new results of ab initio studies for covalent functionalization of GML with ?NH2 groups up to 12.5 % concentration. Our studies are performed in the framework of the density functional theory (DFT) and non-equilibrium Greens function (NEGF). We discuss the stability (adsorption energy), elastic moduli, electronic structure, band gaps, and effective electron masses as a function of the density of the adsorbed molecules. We also show the conductance and current voltage I(V) characteristics for these systems

  3. Electron transport mechanism of thermally oxidized ZnO gas sensors

    International Nuclear Information System (INIS)

    ZnO gas sensor was fabricated by thermal oxidation of metallic Zn at different time periods. The sensors were characterized by I-V measurement with DC voltage, ranging from -2 to 2 volts, in both normal air and H2 gas with concentration from 40 to 160 ppm. The transport mechanism of the carriers was found to be due to thermionic process through both the grain boundaries and the metal-semiconductor junctions. Resistance of the ZnO sensing film is independent of applied voltage in the range 0.5 Va<2 V; however, it is dependent on gas concentration, which makes it useful for gas sensing application.

  4. Functional Anatomy and Biophysical Mechanisms of Fluid Transport in Vascular Plants : Implications for Structural Optimisation in Fossil and Extant Plants

    OpenAIRE

    Konrad, Wilfried.

    2007-01-01

    In plants, water and carbon dioxide molecules are transported either in liquid or gaseous state: From the roots to the leaves water flows as a liquid. Between leaves and atmosphere water and carbon dioxide are exchanged as gases. Accordingly, the driving forces and mechanisms of transport are also different. The driving force of the water transport between roots and leaves is transpiration which takes place in the gas-filled intercellulars of the leaves. Attached to this tissue is a netw...

  5. Reaction mechanisms in the radiolysis of peptides, polypeptides, and proteins. I. Reactions of the peptide main-chain in model systems

    International Nuclear Information System (INIS)

    The object of this review is to bring together and to correlate our present knowledge of products and mechanisms in the radiolysis of peptides, polypeptides and proteins in both aqueous and solid-state systems. Results obtained with various experimental techniques such as product analysis, competition kinetics, ESR spectroscopy and pulse radiolysis are included. Here in part I the emphasis is on the various radiation-induced reactions of the peptide main-chain in model systems. In part II the emphasis is on the radiation chemistry of side-chain loci of the aliphatic, sulfur-containing, aromatic and other unsaturated amino acid residues in similar systems. And, in part III this information on model systems is used in interpreting the mechanisms of chemical change in the radiolysis of proteins in aqueous solution and in the solid state. 60 references

  6. Influence of supplementary cementitious materials on water transport kinetics and mechanical properties of hydrated lime and cement mortars

    Directory of Open Access Journals (Sweden)

    Ince, C.

    2015-06-01

    Full Text Available The purpose of this paper is an investigation of the possible role of supplementary cementitious materials (SCMs on water transport kinetics and mechanical properties of hydrated lime (CL90 and Portland cement (PC mortars. The properties of hydrated lime are significantly different from those of cement and therefore modifying fresh and hardened properties of these mortars are vital for mortar/substrate optimisation in masonry construction. The parameters investigated in this paper often are the main barriers to the use of hydrated lime in construction practice. The results show that transfer sorptivity and time to dewater freshly-mixed hydrated lime mortars can be modified when binder is partially replaced with SCMs. Compressive strength of CL90 mortars is increased systematically with the increased replacement levels of SCMs and the results are supported with the microstructural images. The ability to modify the water transport kinetics and mechanical properties allows compatibility between the mortar and the substrate unit in masonry construction.El objetivo de este artículo es investigar el papel de los materiales cementantes suplementarios (SCMs en la cinética de transporte del agua y en las propiedades mecánicas de los morteros de cal hidratada (CL90 y cemento Portland. Las propiedades de la cal hidratada son significativamente diferentes a las del cemento y por lo tanto el control de las propiedades de los morteros frescos y endurecidos es fundamental en la optimización mortero/substrato en albañilería. Los parámetros estudiados en este trabajo son a menudo las principales barreras para el uso de la cal hidratada en la práctica de la construcción. Los resultados indican que la absortividad y el tiempo necesario para deshidratar morteros de cal hidratada recién mezclados pueden ser controlados cuando el conglomerante es parcialmente remplazado por SCMs. La resistencia a compresión de los morteros CL90 aumenta sistemáticamente con el nivel de sustitución de SCM. Las imágenes microestructurales realizadas, confirman estos resultados. La posibilidad de manipular la cinética de transporte de agua y las propiedades mecánicas permite la compatibilidad entre el mortero y la unidad de sustrato en albañilería.

  7. Palmitate stimulates glucose transport in rat adipocytes by a mechanism involving translocation of the insulin sensitive glucose transporter (GLUT4)

    Science.gov (United States)

    Hardy, R. W.; Ladenson, J. H.; Henriksen, E. J.; Holloszy, J. O.; McDonald, J. M.

    1991-01-01

    In rat adipocytes, palmitate: a) increases basal 2-deoxyglucose transport 129 +/- 27% (p less than 0.02), b) decreases the insulin sensitive glucose transporter (GLUT4) in low density microsomes and increases GLUT4 in plasma membranes and c) increases the activity of the insulin receptor tyrosine kinase. Palmitate-stimulated glucose transport is not additive with the effect of insulin and is not inhibited by the protein kinase C inhibitors staurosporine and sphingosine. In rat muscle, palmitate: a) does not affect basal glucose transport in either the soleus or epitrochlearis and b) inhibits insulin-stimulated glucose transport by 28% (p less than 0.005) in soleus but not in epitrochlearis muscle. These studies demonstrate a potentially important differential role for fatty acids in the regulation of glucose transport in different insulin target tissues.

  8. Transport mechanisms of uranium released to the coolant from fuel defects

    International Nuclear Information System (INIS)

    Fuel performance at domestic CANDU-600s, Point Lepreau and Gentilly, has been very good, with only a small number of fuel defects releasing uranium to the coolant. The in-core monitoring on these early fuel defects using the delayed neutron system, provides some insight into uranium transport mechanisms and how they influence signal trends. Better understanding of these mechanisms, will assist the station operator in responding to trend changes and will ultimately provide guidance in assigning removal priorities should several fuel defects occur simultaneously. The average delayed neutron signal of all channels is the key parameter for monitoring fuel performance in-core, and should be regarded as an early warning indicator of fuel performance problems

  9. Photoluminescence and carrier transport mechanisms of silicon-rich silicon nitride light emitting device

    International Nuclear Information System (INIS)

    Highlights: • Amorphous silicon quantum dots (a-Si QDs) embedded in silicon nitride were fabricated using plasma-enhanced chemical vapor deposition (PECVD). • Two different excitation sources were used to investigate the PL mechanisms. • Light emitting diode (LED) with ITO/SiNx/p-Si/Al structure was fabricated and the carrier transport mechanisms were investigated. - Abstract: Silicon-rich silicon nitride (SRSN) films were prepared on p-type silicon substrates using plasma-enhanced chemical vapor deposition (PECVD). Small size (∼3 nm) amorphous silicon quantum dots (a-Si QDs) were obtained after 1100 °C annealing. Two different excitation sources, namely 325 nm and 532 nm lasers, were introduced to investigate the photoluminescence (PL) properties. The PL bands pumped by 325 nm laser at ∼2.90 eV and ∼1.80 eV were contributed to the radiative centers from N dangling bonds (DBs), while the dominant PL bands at 2.10 eV were ascribed to the instinct PL centers in the nitride matrix. However, PL emissions from band tail luminescence and quantum confined effect (QCE) in a-Si QDs were found under the excitation of 532 nm laser. Light emitting diode (LED) with ITO/SiNx/p-Si/Al structure was fabricated. Intensely red light emission was observed by naked eyes at room temperature under forward 20 V. Three different carrier transport mechanisms, namely Poole–Frenkel (P–F) tunneling, Fowler–Nordheim (F–N) tunneling and space charge limited current (SCLC), were found to fit different electric field regions. These results help to understand the PL mechanisms and to optimize the fabrication of a-Si QD LED

  10. Photoluminescence and carrier transport mechanisms of silicon-rich silicon nitride light emitting device

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Wugang [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Zeng, Xiangbin, E-mail: eexbzeng@mail.hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Yao, Wei [Shenzhen Institute of Huazhong University of Science and Technology, Shenzhen 518000 (China); Wen, Xixing [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2015-10-01

    Highlights: • Amorphous silicon quantum dots (a-Si QDs) embedded in silicon nitride were fabricated using plasma-enhanced chemical vapor deposition (PECVD). • Two different excitation sources were used to investigate the PL mechanisms. • Light emitting diode (LED) with ITO/SiNx/p-Si/Al structure was fabricated and the carrier transport mechanisms were investigated. - Abstract: Silicon-rich silicon nitride (SRSN) films were prepared on p-type silicon substrates using plasma-enhanced chemical vapor deposition (PECVD). Small size (∼3 nm) amorphous silicon quantum dots (a-Si QDs) were obtained after 1100 °C annealing. Two different excitation sources, namely 325 nm and 532 nm lasers, were introduced to investigate the photoluminescence (PL) properties. The PL bands pumped by 325 nm laser at ∼2.90 eV and ∼1.80 eV were contributed to the radiative centers from N dangling bonds (DBs), while the dominant PL bands at 2.10 eV were ascribed to the instinct PL centers in the nitride matrix. However, PL emissions from band tail luminescence and quantum confined effect (QCE) in a-Si QDs were found under the excitation of 532 nm laser. Light emitting diode (LED) with ITO/SiNx/p-Si/Al structure was fabricated. Intensely red light emission was observed by naked eyes at room temperature under forward 20 V. Three different carrier transport mechanisms, namely Poole–Frenkel (P–F) tunneling, Fowler–Nordheim (F–N) tunneling and space charge limited current (SCLC), were found to fit different electric field regions. These results help to understand the PL mechanisms and to optimize the fabrication of a-Si QD LED.

  11. Evaluation of the film formation and the charge transport mechanism of indium tin oxide nanoparticle films

    International Nuclear Information System (INIS)

    The structure formation and charge transfer of thin nanoparticulate indium tin oxide (ITO) films prepared by dip-coating was studied as a function of stabilizer before and after annealing at different temperatures. The analysis of the film structure by optical methods revealed that it is a function of the stability. Suspensions containing an optimum stabilizer concentration of 0.1 mol/l resulted in densely packed films with a peak specific conductivity of 8.3 S cm-1 after annealing at 550 oC for 1 h in air and 121 S cm-1 after annealing in forming gas at 250 oC for 1 h, respectively. Furthermore, for the densely packed films fluctuation-induced tunnelling was found to be the dominant charge transport mechanism, whereas for the low density films a thermally activated charge transport was observed. That the films of maximum density showed a metallic charge transport behaviour at temperatures above 300 K indicated the optimal contact between ITO particles had been achieved.

  12. Perturbation of the Electron Transport Mechanism by Proton Intercalation in Nanoporous TiO2 Films

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, A. F.; Zhu, K.; Erslev, P. T.; Kim, J. Y.; Neale, N. R.; Frank, A. J.

    2012-04-11

    This study addresses a long-standing controversy about the electron-transport mechanism in porous metal oxide semiconductor films that are commonly used in dye-sensitized solar cells and related systems. We investigated, by temperature-dependent time-of-flight measurements, the influence of proton intercalation on the electron-transport properties of nanoporous TiO{sub 2} films exposed to an ethanol electrolyte containing different percentages of water (0-10%). These measurements revealed that increasing the water content in the electrolyte led to increased proton intercalation into the TiO{sub 2} films, slower transport, and a dramatic change in the dependence of the thermal activation energy (E{sub a}) of the electron diffusion coefficient on the photogenerated electron density in the films. Random walk simulations based on a microscopic model incorporating exponential conduction band tail (CBT) trap states combined with a proton-induced shallow trap level with a long residence time accounted for the observed effects of proton intercalation on E{sub a}. Application of this model to the experimental results explains the conditions under which E{sub a} dependence on the photoelectron density is consistent with multiple trapping in exponential CBT states and under which it appears at variance with this model.

  13. The relative importance of decomposition and transport mechanisms in accounting for soil organic carbon profiles

    Directory of Open Access Journals (Sweden)

    B. Guenet

    2013-04-01

    Full Text Available Soil is the major terrestrial reservoir of carbon and a substantial part of this carbon is stored in deep layers, typically deeper than 50 cm below the surface. Several studies underlined the quantitative importance of this deep soil organic carbon (SOC pool and models are needed to better understand this stock and its evolution under climate and land-uses changes. In this study, we tested and compared three simple theoretical models of vertical transport for SOC against SOC profiles measurements from a long-term bare fallow experiment carried out by the Central-Chernozem State Natural Biosphere Reserve in the Kursk Region of Russia. The transport schemes tested are diffusion, advection and both diffusion and advection. They are coupled to three different formulations of soil carbon decomposition kinetics. The first formulation is a first order kinetics widely used in global SOC decomposition models; the second one, so-called "priming" model, links SOC decomposition rate to the amount of fresh organic matter, representing the substrate interactions. The last one is also a first order kinetics, but SOC is split into two pools. Field data are from a set of three bare fallow plots where soil received no input during the past 20, 26 and 58 yr, respectively. Parameters of the models were optimised using a Bayesian method. The best results are obtained when SOC decomposition is assumed to be controlled by fresh organic matter (i.e., the priming model. In comparison to the first-order kinetic model, the priming model reduces the overestimation in the deep layers. We also observed that the transport scheme that improved the fit with the data depended on the soil carbon mineralisation formulation chosen. When soil carbon decomposition was modelled to depend on the fresh organic matter amount, the transport mechanism which improved best the fit to the SOC profile data was the model representing both advection and diffusion. Interestingly, the older the bare fallow is, the lesser the need for diffusion is, suggesting that stabilised carbon may not be transported within the profile by the same mechanisms than more labile carbon.

  14. JOYO MK-III heat transport system renovation operation. Primary heat transport mechanical system (IHXs (intermediate heat exchangers))

    International Nuclear Information System (INIS)

    The MK-III project to improve the irradiation capability of the experimental fast reactor JOYO have been carried out since 1987. The increase of fast neutron flux and the enlargement of irradiation field increase the reactor thermal power from 100 MWt to 140 MWt. To accommodate the increased thermal power, the IHXs and the IHX connecting piping were replaced. The IHXs were replaced with securing cooling system boundary in high dose rate surroundings and very limited operation space of the radiation controlled area in the containment vessel. Primary sodium contains radioactive 22Na, 24Na and radioactive CPs such as 60Co and 54Mn, and this sodium adhered to the inner surface of IHXs and pipe. Therefore, the renovation procedure and method were carefully examined based on the JOYO operation and maintenance experiences and research and development results on the sodium handling technique. The major results obtained in the primary heat transport mechanical system (IHXs) renovation operation were shown as follows; (1) The mock up tests to optimize the operating methods, to check the operability and for workers training were useful for reduction of radiation exposure by shortening the operation time in high dose rate surrounding. (2) The effectiveness of seal bag for prevention of impurity ingress to the sodium system and contamination during sodium boundary opening (cutting pipes, sodium removal and welding pipes) was confirmed. (3) The pipes were cut without foreign object such as cutting piece and tool ingress by careful examination of cutting procedure and methods such as bite, roller cutter. (4) The temporary closing equipment such as seal cap and seal plug were effectively worked to seal the cooling system boundary between cutting and welding pipes. (5) Sodium adhered on the inner surfaces of pipe was effectively and safely removed by a mechanical scraper or drill and a cloth moistened by a mixture of alcohol and water. (6) Control of low gas pressure difference between cover gas pressure and seal bag pressure and monitoring of pipe surface temperature is useful to avoid welding flaw during pipe welding in the seal bag. Replacement operations started October 30, 2000 and finished September 21, 2001 without major troubles. The above results obtained this operation will be applied not only the operation and maintenance activity of JOYO but also the renovation of FBR and design for future sodium cooled FBR. (author)

  15. The effect of mechanical twisting on oxygen ionic transport in solid-state energy conversion membranes

    Science.gov (United States)

    Shi, Yanuo; Bork, Alexander Hansen; Schweiger, Sebastian; Rupp, Jennifer Lilia Marguerite

    2015-07-01

    Understanding `electro-chemo-mechanics in oxygen ion conducting membranes represents a foundational step towards new energy devices such as micro fuel cells and oxygen or fuel separation membranes. For ionic transport in macro crystalline electrolytes, doping is conventionally used to affect oxygen ionic association/migration energies. Recently, tuning ionic transport in films through lattice strain conveyed by substrates or heterostructures has generated much interest. However, reliable manipulation of strain states to twist the ionic conduction in real micro energy devices remains intractable. Here, we demonstrate that the oxygen ionic conductivity clearly correlates with the compressive strain energy acting on the near order of the electrolyte lattices by comparing thin-film ceria-based membrane devices against substrate-supported flat structures. It is possible to capitalize on this phenomenon with a smart choice of strain patterns achieved through microelectrode design. We highlight the importance of electro-chemo-mechanics in the electrolyte material for the next generation of solid-state energy conversion microdevices.

  16. Current transport mechanisms in plasma-enhanced atomic layer deposited AlN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Altuntas, Halit, E-mail: altunhalit@gmail.com, E-mail: biyikli@unam.bilkent.edu.tr [Faculty of Science, Department of Physics, Cankiri Karatekin University, Cankiri 18100 (Turkey); Ozgit-Akgun, Cagla; Donmez, Inci; Biyikli, Necmi, E-mail: altunhalit@gmail.com, E-mail: biyikli@unam.bilkent.edu.tr [National Nanotechnology Research Center (UNAM), Bilkent University, Bilkent, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Bilkent, Ankara 06800 (Turkey)

    2015-04-21

    Here, we report on the current transport mechanisms in AlN thin films deposited at a low temperature (i.e., 200 °C) on p-type Si substrates by plasma-enhanced atomic layer deposition. Structural characterization of the deposited AlN was carried out using grazing-incidence X-ray diffraction, revealing polycrystalline films with a wurtzite (hexagonal) structure. Al/AlN/ p-Si metal-insulator-semiconductor (MIS) capacitor structures were fabricated and investigated under negative bias by performing current-voltage measurements. As a function of the applied electric field, different types of current transport mechanisms were observed; i.e., ohmic conduction (15.2–21.5 MV/m), Schottky emission (23.6–39.5 MV/m), Frenkel-Poole emission (63.8–211.8 MV/m), trap-assisted tunneling (226–280 MV/m), and Fowler-Nordheim tunneling (290–447 MV/m). Electrical properties of the insulating AlN layer and the fabricated Al/AlN/p-Si MIS capacitor structure such as dielectric constant, flat-band voltage, effective charge density, and threshold voltage were also determined from the capacitance-voltage measurements.

  17. Fracture mechanics based design for radioactive material transport packagings -- Historical review

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J.A.; Salzbrenner, D.; Sorenson, K.; McConnell, P.

    1998-04-01

    The use of a fracture mechanics based design for the radioactive material transport (RAM) packagings has been the subject of extensive research for more than a decade. Sandia National Laboratories (SNL) has played an important role in the research and development of the application of this technology. Ductile iron has been internationally accepted as an exemplary material for the demonstration of a fracture mechanics based method of RAM packaging design and therefore is the subject of a large portion of the research discussed in this report. SNL`s extensive research and development program, funded primarily by the U. S. Department of Energy`s Office of Transportation, Energy Management and Analytical Services (EM-76) and in an auxiliary capacity, the office of Civilian Radioactive Waste Management, is summarized in this document along with a summary of the research conducted at other institutions throughout the world. In addition to the research and development work, code and standards development and regulatory positions are also discussed.

  18. Structure, Mechanics, and Transport in Block Copolymer-Nanoparticle Composites at the Macroscopic and Nanometer Lengthscales

    Science.gov (United States)

    Cheng, Vicki Alice

    2013-08-01

    Pluronic triblock copolymers self-assemble in water to form thermoreversible soft solids that comprise of periodically spaced micelles. The interstitial spacings of these micellar crystals are on the order of tens of nanometers, and have been used to template comparably sized nanoparticles with hydrodynamic diameters (Dh) ranging from 4-7 nm. Here, nanoparticle diffusivity is studied and modeled in these self-assembling block copolymers across a range of polymer concentrations. Transport in the disordered micellar solution is described as diffusion through a polymer solution, while diffusive behavior in the structured micellar phase is modeled as an activated hopping process. The effects of protein loading, shear alignment, particle type, and block copolymer composition on particle transport are also examined, and they affect particle diffusivity to varying degrees. Block copolymer architecture influences the micellar structure and dimensions, which in turn affects protein templating and protein aggregation behavior. The overall micellar dimensions are smaller in block copolymers with shorter block lengths, and efforts to template particles which are larger than the interstitial spacings result in changes to the block copolymer structure and mechanics. It is possible, however, for block copolymers to accommodate a limited amount of particles which are larger than the estimated micellar interstitial site. When examining protein aggregation behavior in block copolymers with varying PEO chain lengths, striking differences in aggregation behavior are observed as well. Ultimately, this work underscores the interplay between the structure, mechanics, and transport behavior in nanoparticle-block copolymer composites, and this knowledge can be applied towards the design of self-assembling nanoscale materials.

  19. Mechanical design engineering. NASA/university advanced design program: Lunar Bulk Material Transport Vehicle

    Science.gov (United States)

    Daugherty, Paul; Griner, Stewart; Hendrix, Alan; Makarov, Chris; Martiny, Stephen; Meyhoefer, Douglas Ralph; Platt, Cody Claxton; Sivak, John; Wheeler, Elizabeth Fitch

    1988-01-01

    The design of a Lunar Bulk Material Transport Vehicle (LBMTV) is discussed. Goals set in the project include a payload of 50 cubic feet of lunar soil with a lunar of approximately 800 moon-pounds, a speed of 15 mph, and the ability to handle a grade of 20 percent. Thermal control, an articulated steering mechanism, a dump mechanism, a self-righting mechanism, viable power sources, and a probable control panel are analyzed. The thermal control system involves the use of small strip heaters to heat the housing of electronic equipment in the absence of sufficient solar radiation and multi-layer insulation during periods of intense solar radiation. The entire system uses only 10 W and weighs about 60 pounds, or 10 moon-pounds. The steering mechanism is an articulated steering joint at the center of the vehicle. It utilizes two actuators and yields a turning radius of 10.3 feet. The dump mechanism rotates the bulk material container through an angle of 100 degree using one actuator. The self-righting mechanism consists of two four bar linkages, each of which is powered by the same size actuator as the other linkages. The LBMTV is powered by rechargeable batteries. A running time of at least two hours is attained under a worst case analysis. The weight of the batteries is 100 pounds. A control panel consisting of feedback and control instruments is described. The panel includes all critical information necessary to control the vehicle remotely. The LBMTV is capable of handling many types of cargo. It is able to interface with many types of removable bulk material containers. These containers are made to interface with the three-legged walker, SKITTER. The overall vehicle is about 15 feet in length and has a weight of about 1000 pounds, or 170 lunar pounds.

  20. Transport

    International Nuclear Information System (INIS)

    Transport is one of the major causes of environmental damage in Austria. Energy consumption, pollutants emissions, noise emissions, use of surfaces, sealing of surfaces, dissection of ecosystems and impact on landscape are the most significant environmental impacts caused by it. An overview of the transport development of passengers and freight in Austria is presented. Especially the energy consumption growth, carbon dioxide and nitrogen oxide emissions by type of transport, and the emissions development (HC, particle and carbon monoxide) of goods and passengers transport are analyzed covering the years 1980 - 1999. The health cost resulting from transport-related air pollution in Austria is given and measures to be taken for an effective control of the transport sector are mentioned. Figs. 8, Table 1. (nevyjel)

  1. Elastic tunneling charge transport mechanisms in silicon quantum dots /SiO{sub 2} thin films and superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Illera, S., E-mail: sillera@el.ub.edu; Prades, J. D.; Cirera, A. [MIND/IN2UB Departament d' Electrònica, Universitat de Barcelona, C/Martí i Franquès 1, E-08028 Barcelona (Spain)

    2015-05-07

    The role of different charge transport mechanisms in Si/SiO{sub 2} structures has been studied. A theoretical model based on the Transfer Hamiltonian Formalism has been developed to explain experimental current trends in terms of three different elastic tunneling processes: (1) trap assisted tunneling; (2) transport through an intermediate quantum dot; and (3) direct tunneling between leads. In general, at low fields carrier transport is dominated by the quantum dots whereas, for moderate and high fields, transport through deep traps inherent to the SiO{sub 2} is the most relevant process. Besides, current trends in Si/SiO{sub 2} superlattice structure have been properly reproduced.

  2. Evidence for enhanced cross-field transport mechanisms in the TCV Snowflake divertor

    Science.gov (United States)

    Vijvers, Wouter

    2015-11-01

    TCV experiments demonstrate that cross-field plasma transport is enhanced in the Snowflake divertor (SFD) compared to a standard single-null divertor (SND). This enhanced cross-field transport spreads the exhaust power over a larger surface area than can be achieved by magnetic geometry alone and, thereby, reduces the peak heat flux. Comparison of the experiments with modelling identifies steepened radial gradients, ExB drift effects, and βp-driven instabilities as the responsible transport mechanisms. The uncovered physics is also relevant to the SND and may help improve predictive models for the target profiles in ITER and DEMO. In SFD variants with an X-point in the scrape-off layer (SOL), part of the heat flux profile is split off and redirected to an additional target. The resulting steepened radial gradients enhance cross-field diffusion. This is confirmed by EMC3-Eirene simulations, which show a factor two reduction of the parallel heat flux, even if diffusivities remain constant. Theoretical analysis predicts enhanced ExB drifts in the SFD by increased poloidal gradients of the temperature and density. The predictions are confirmed by target heat and particle flux measurements in dedicated experiments with both toroidal field directions. Cross-field convection by curvature-driven modes at high βp (``churning modes'') explains the large fluxes into the private flux region of the SFD. This activates the extra targets and reduces the peak power to the primary targets up to a factor four. This mechanism is expected to be most effective when the divertor conditions are most severe: near the separatrix of a narrow, high-pressure SOL of a large tokamak. These and other alternative divertor configurations thus provide potential solutions to the power exhaust challenge, as well as laboratories to study SOL transport, one of the most important topics in tokamak research. This project was carried out with financial support from NWO. The work was carried out within the framework of the EUROfusion Consortium and received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053.

  3. Oxygen transport and reaction mechanisms in rhenium gate contacts on hafnium oxide films on Si

    International Nuclear Information System (INIS)

    Oxygen transport and incorporation were investigated following postdeposition annealing of metal-oxide-semiconductor structures having ultrathin rhenium films as metal electrode and HfO2 films as dielectric on Si(001). Isotopic tracing, nuclear reaction analysis, narrow resonant nuclear reaction profiling, and x-ray photoelectron spectroscopy were used to pursue this investigation. For annealing temperatures below 400 deg. C, oxygen from the gas phase incorporates mainly in near-surface regions of the overlying Re cap. Significant oxygen incorporation into the HfO2 films is observed only after annealing at 500 deg. C. The present results are discussed considering that supplying oxygen to the metal/dielectric interface can cause device threshold voltage shifts

  4. Review: Role of Chemistry, Mechanics, and Transport on Well Integrity in CO2 Storage Environments

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Susan A.; Carey, William J.; Dzombak, David; Huerta, Nicolas J.; Li, Li; Richard, Tom; Um, Wooyong; Walsh, Stuart D.; ZHANG, LIWEI

    2016-01-11

    Among the various risks associated with CO2 storage in deep geologic formations, wells are important potential pathways for fluid leaks and groundwater contamination. Injection of CO2 will perturb the storage reservoir and any wells that penetrate the CO2 or pressure footprints are potential pathways for leakage of CO2 and/or reservoir brine. Well leakage is of particular concern for regions with a long history of oil and gas exploration because they are top candidates for geologic CO2 storage sites. This review explores in detail the ability of wells to retain their integrity against leakage with careful examination of the coupled physical and chemical processes involved. Understanding time-dependent leakage is complicated by the changes in fluid flow, solute transport, chemical reactions, and mechanical stresses over decade or longer time frames for site operations and monitoring. Almost all studies of the potential for well leakage have been laboratory based, as there are limited data on field-scale leakage. When leakage occurs by diffusion only, laboratory experiments show that while CO2 and CO2-saturated brine react with cement and casing, the rate of degradation is transport-limited and alteration of cement and casing properties is low. When a leakage path is already present due to cement shrinkage or fracturing, gaps along interfaces (e.g. casing/cement or cement/rock), or casing failures, chemical and mechanical alteration have the potential to decrease or increase leakage risks. Laboratory experiments and numerical simulations have shown that mineral precipitation or closure of strain-induced fractures can seal a leak pathway over time or conversely open pathways depending on flow-rate, chemistry, and the stress state. Experiments with steel/cement and cement/rock interfaces have indicated that protective mechanisms such as metal passivation, chemical alteration, mechanical deformation, and pore clogging can also help mitigate leakage. The specific rate and nature of alteration depends on the cement, brine, and injected fluid compositions. For example, the presence of co-injected gases (e.g. O2, H2S, and SO2) and pozzolan amendments (fly ash) to cement influences the rate and the nature of cement reactions. A more complete understanding of the coupled physical-chemical mechanisms involved with sealing and opening of leakage pathways is needed. An important challenge is to take empirically based chemical, mechanical, and transport models reviewed here and assess leakage risk for carbon storage at the field scale. Field observations to accompany laboratory and modeling studies are critical to validating understanding of leakage risk. Long-term risk at the field scale is an area of active research made difficult by the large variability of material types (cement, geologic material, casing), field conditions (pressure, temperature, gradient in potential, residence time), and leaking fluid composition (CO2, co-injected gases, brine). Of particular interest are the circumstances when sealing and other protective mechanisms are likely to be effective, when they are likely to fail, and the zone of uncertainty between these two extremes.

  5. Progress in Solving the Elusive Ag Transport Mechanism in TRISO Coated Particles: What is new?

    Energy Technology Data Exchange (ETDEWEB)

    Isabella Van Rooyen

    2014-10-01

    The TRISO particle for HTRs has been developed to an advanced state where the coating withstands internal gas pressures and retains fission products during irradiation and under postulated accidents. However, one exception is Ag that has been found to be released from high quality TRISO coated particles when irradiated and can also during high temperature accident heating tests. Although out- of- pile laboratory tests have never hither to been able to demonstrate a diffusion process of Ag in SiC, effective diffusion coefficients have been derived to successfully reproduce measured Ag-110m releases from irradiated HTR fuel elements, compacts and TRISO particles It was found that silver transport through SiC does not proceed via bulk volume diffusion. Presently grain boundary diffusion that may be irradiation enhanced either by neutron bombardment or by the presence of fission products such as Pd, are being investigated. Recent studies of irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), transmission kukuchi diffraction (TKD) patterns and high resolution transmission electron microscopy (HRTEM) have been used to further the understanding of Ag transport through TRISO particles. No silver was observed in SiC grains, but Ag was identified at triple-points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in some of the very same triple junctions, but this could be related to silver behavior as Ag-110m decays to Cd-110. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries and in most SiC grain boundaries and the potential role of Pd in the transport of Ag will be discussed.

  6. Molecular mechanisms regulating oxygen transport and consumption in high altitude and hibernating mammals

    DEFF Research Database (Denmark)

    Revsbech, Inge Grønvall

    2016-01-01

    The aim of this thesis is to broaden the knowledge of molecular mechanisms of adjustment in oxygen (O2) uptake, conduction, delivery and consumption in mammals adapted to extreme conditions. For this end, I have worked with animals living at high altitude as an example of environmental hypoxia, and...... repeatedly found adaptive traits in animals living at high altitude and in hibernating mammals during hibernation compared with the active state. Factors that affect O2 affinity of Hb include temperature, H+/CO2 via the Bohr effect as well as Cl- and organic phosphates, in mammals mainly 2...

  7. Transportation R and D included in thermal and mechanical sciences program

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-03-01

    Argonne National Laboratory is a multiprogram research and development laboratory operated by The University of Chicago for the US Department of Energy. At Argonne, applied research in thermal and mechanical sciences is performed within the Thermal and Mechanical Sciences Section of the Energy Technology Division. Current program areas include compact evaporators and condensers for the process and transportation industries, ice slurries for district cooling, advanced fluids for improved heat transfer and reduced pressure drop, flow-induced vibration and flow distribution in shell-and-tube heat exchangers, and dynamics and control of maglev systems. In general, the objective of the research is to extend the technology base in each of these areas and to facilitate its application in solving problems of importance to US industries and utilities. This is accomplished by developing validated design correlations and predictive methods. The staff of the Thermal and Mechanical Sciences Section have extensive experimental and analytical experience in heat transfer, multiphase flow, structural dynamics and control, fluid-structure interaction, transient flow and mixing, thermally driven flows, and flow visualization using ultra-high-speed video. Large, general-purpose test facilities and smaller, single-purpose test apparatuses are available for experiments and component design evaluation. A world-class capability in the study of flow-induced vibrations exists within the Section. Individual fact sheets, describing currently active research program areas, related facilities, and listing, as a contact, the principal investigator, are included.

  8. Dissecting the Molecular Mechanism of Nucleotide-Dependent Activation of the KtrAB K+ Transporter

    Science.gov (United States)

    Szollosi, Andras; Vieira-Pires, Ricardo S.; Teixeira-Duarte, Celso M.; Rocha, Rita; Morais-Cabral, Joo H.

    2016-01-01

    KtrAB belongs to the Trk/Ktr/HKT superfamily of monovalent cation (K+ and Na+) transport proteins that closely resemble K+ channels. These proteins underlie a plethora of cellular functions that are crucial for environmental adaptation in plants, fungi, archaea, and bacteria. The activation mechanism of the Trk/Ktr/HKT proteins remains unknown. It has been shown that ATP stimulates the activity of KtrAB while ADP does not. Here, we present X-ray structural information on the KtrAB complex with bound ADP. A comparison with the KtrAB-ATP structure reveals conformational changes in the ring and in the membrane protein. In combination with a biochemical and functional analysis, we uncover how ligand-dependent changes in the KtrA ring are propagated to the KtrB membrane protein and conclude that, despite their structural similarity, the activation mechanism of KtrAB is markedly different from the activation mechanism of K+ channels. PMID:26771197

  9. Transportation R and D included in thermal and mechanical sciences program

    Science.gov (United States)

    1995-06-01

    Argonne National Laboratory is a multiprogram research and development laboratory operated by The University of Chicago for the US Department of Energy. At Argonne, applied research in thermal and mechanical sciences is performed within the Thermal and Mechanical Sciences Section of the Energy Technology Division. Current program areas include compact evaporators and condensers for the process and transportation industries, ice slurries for district cooling, advanced fluids for improved heat transfer and reduced pressure drop, flow-induced vibration and flow distribution in shell-and-tube heat exchangers, and dynamics and control of maglev systems. In general, the objective of the research is to extend the technology base in each of these areas and to facilitate its application in solving problems of importance to US industries and utilities. This is accomplished by developing validated design correlations and predictive methods. The staff of the Thermal and Mechanical Sciences Section have extensive experimental and analytical experience in heat transfer, multiphase flow, structural dynamics and control, fluid-structure interaction, transient flow and mixing, thermally driven flows, and flow visualization using ultra-high-speed video. Large, general-purpose test facilities and smaller, single-purpose test apparatuses are available for experiments and component design evaluation. A world-class capability in the study of flow-induced vibrations exists within the section. Individual fact sheets, describing currently active research program areas and related facilities and listing, as a contact, the principal investigator, are included.

  10. Dark current transport mechanisms in narrow-gap heterojunctions for IR arrays

    Science.gov (United States)

    Sizov, Fiodor F.; Gumenjuk-Sichevskaya, Joanna V.; Sidorov, Yuri G.; Vasilev, Vladimir; Golenkov, Alexandr G.; Zabudsky, Vyacheslav V.; Reva, Vladimir P.; Derkach, Yurii P.; Tetyorkin, Vladimir V.

    2001-11-01

    Dark carrier transport mechanisms in narrow-gap Hg1-xCdxTe multilayer structures and Pb1-zSnzTe/PbTe1-yS(Se)y heterojunctions at T~80 K for applications in IR arrays are analyzed and compared with homojunction mercury-cadmium telluride (MCT) photodiode characteristics in the temperature range T~70-150 K. In the analysis procedure two major current mechanisms were included into the current balance equations: trap-assisted tunneling (TAT) and Shockley-Reed-Hall (SRH) generation-recombination processes for a defect trap level. Other current mechanisms (e.g., band-to-band tunneling, bulk diffusion) were taken into account as additive contributions. For TAT the tunneling rate characteristics were calculated within the k-p-approximation. Using donor and acceptor concentrations, trap level energies and concentrations, and in-junction trap level lifetimes as fitting parameters, good agreement with experimental data for HgCdTe and PbSnTe heterojunction and homojunction diodes was obtained, which allows one to predict the diode parameters from the known material characteristics. Photodiode or array parameters itself, or with CCD readouts, or CCD readouts separately were tested to study the influence of readout cascade on the diodes' properties.

  11. Quantum mechanics of excitation transport in photosynthetic complexes: a key issues review

    Science.gov (United States)

    Levi, Federico; Mostarda, Stefano; Rao, Francesco; Mintert, Florian

    2015-07-01

    For a long time microscopic physical descriptions of biological processes have been based on quantum mechanical concepts and tools, and routinely employed by chemical physicists and quantum chemists. However, the last ten years have witnessed new developments on these studies from a different perspective, rooted in the framework of quantum information theory. The process that more, than others, has been subject of intense research is the transfer of excitation energy in photosynthetic light-harvesting complexes, a consequence of the unexpected experimental discovery of oscillating signals in such highly noisy systems. The fundamental interdisciplinary nature of this research makes it extremely fascinating, but can also constitute an obstacle to its advance. Here in this review our objective is to provide an essential summary of the progress made in the theoretical description of excitation energy dynamics in photosynthetic systems from a quantum mechanical perspective, with the goal of unifying the language employed by the different communities. This is initially realized through a stepwise presentation of the fundamental building blocks used to model excitation transfer, including protein dynamics and the theory of open quantum system. Afterwards, we shall review how these models have evolved as a consequence of experimental discoveries; this will lead us to present the numerical techniques that have been introduced to quantitatively describe photo-absorbed energy dynamics. Finally, we shall discuss which mechanisms have been proposed to explain the unusual coherent nature of excitation transport and what insights have been gathered so far on the potential functional role of such quantum features.

  12. Buffer transport mechanisms in intentionally carbon doped GaN heterojunction field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Uren, Michael J.; Csar, Markus; Kuball, Martin [Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Gajda, Mark A. [NXP Semiconductors, Bramhall Moor Lane, Hazel Grove, Stockport SK7 5BJ (United Kingdom)

    2014-06-30

    Temperature dependent pulsed and ramped substrate bias measurements are used to develop a detailed understanding of the vertical carrier transport in the buffer layers in a carbon doped GaN power heterojunction field effect transistor. Carbon doped GaN and multiple layers of AlGaN alloy are used in these devices to deliver an insulating and strain relieved buffer with high breakdown voltage capability. However, understanding of the detailed physical mechanism for its operation is still lacking. At the lowest electric fields (<10 MV/m), charge redistribution within the C doped layer is shown to occur by hole conduction in the valence band with activation energy 0.86?eV. At higher fields, leakage between the two-dimensional electron gas and the buffer dominates occurring by a Poole-Frenkel mechanism with activation energy ?0.65?eV, presumably along threading dislocations. At higher fields still, the strain relief buffer starts to conduct by a field dependent process. Balancing the onset of these leakage mechanisms is essential to allow the build-up of positive rather than negative space charge, and thus minimize bulk-related current-collapse in these devices.

  13. Integrated Radiation Transport and Thermo-Mechanics Simulation of a PWR Assembly

    International Nuclear Information System (INIS)

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step towards incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source terms, such as the neutron flux distribution, coolant conditions, and assembly mechanical stresses, of traditional (single-pin) nuclear fuel performance simulation. AMPFuel was used to model an entire 17 x 17 Pressurized Water Reactor (PWR) fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics), including the fuel, gap, and cladding of each of the 264 fuel pins, the 25 guide tubes, top and bottom structural regions, and the upper and lower (neutron) reflector regions. The final full-assembly calculation was executed on Jaguar (Cray XT5) at the Oak Ridge Leadership Computing Facility using 40,000 cores in under 10 hours to model over 162 billion degrees of freedom for 10 loading steps.

  14. Free Energies of Ion Binding in the Bacterial CLC-ec1 Chloride Transporter with Implications for the Transport Mechanism and Selectivity.

    Science.gov (United States)

    Chen, Zhihong; Beck, Thomas L

    2016-03-31

    The chloride channel/transporter family of proteins facilitates anion transport across biological membranes. There is extensive physiological and bioinformatic evidence that the channels and transporters are closely related. Each monomer of a homodimeric CLC transport protein contains a narrow selectivity filter. Investigating the ion binding properties inside the filter is crucial for understanding key mechanistic states during ion transit. Here computer simulations are used to explore the free energies of Cl(-) ions in the binding sites of the wild-type CLC-ec1 transporter and its mutant E148A. Specifically, a local molecular field theory approach for free energy calculations is exploited to compute the absolute free energies in water and in the protein binding sites. The calculations indicate a close synergy between anion binding and protonation of the external glutamate gate. Electrostatic differences between the bacterial CLC-ec1 and eukaryotic CmCLC transporters revealed by these and other simulations help to rationalize the observed differing structures in the pore region. In addition, quantum chemical calculations on the F(-), Cl(-), and Br(-) ions in the central binding site are used to examine ion selectivity. The calculations show a significant extent of charge transfer from the ion to the nearby residues. The computed free energies, in conjunction with experimental measurements, place constraints on proposed mechanisms for the transport cycle. PMID:26967203

  15. Diffusion and bulk flow in phloem loading: A theoretical analysis of the polymer trap mechanism for sugar transport in plants

    Science.gov (United States)

    Dlger, Julia; Rademaker, Hanna; Liesche, Johannes; Schulz, Alexander; Bohr, Tomas

    2014-10-01

    Plants create sugar in the mesophyll cells of their leaves by photosynthesis. This sugar, mostly sucrose, has to be loaded via the bundle sheath into the phloem vascular system (the sieve elements), where it is distributed to growing parts of the plant. We analyze the feasibility of a particular loading mechanism, active symplasmic loading, also called the polymer trap mechanism, where sucrose is transformed into heavier sugars, such as raffinose and stachyose, in the intermediary-type companion cells bordering the sieve elements in the minor veins of the phloem. Keeping the heavier sugars from diffusing back requires that the plasmodesmata connecting the bundle sheath with the intermediary cell act as extremely precise filters, which are able to distinguish between molecules that differ by less than 20% in size. In our modeling, we take into account the coupled water and sugar movement across the relevant interfaces, without explicitly considering the chemical reactions transforming the sucrose into the heavier sugars. Based on the available data for plasmodesmata geometry, sugar concentrations, and flux rates, we conclude that this mechanism can in principle function, but that it requires pores of molecular sizes. Comparing with the somewhat uncertain experimental values for sugar export rates, we expect the pores to be only 5%-10% larger than the hydraulic radius of the sucrose molecules. We find that the water flow through the plasmodesmata, which has not been quantified before, contributes only 10%-20% to the sucrose flux into the intermediary cells, while the main part is transported by diffusion. On the other hand, the subsequent sugar translocation into the sieve elements would very likely be carried predominantly by bulk water flow through the plasmodesmata. Thus, in contrast to apoplasmic loaders, all the necessary water for phloem translocation would be supplied in this way with no need for additional water uptake across the plasma membranes of the phloem.

  16. A mechanism of viral immune evasion revealed by cryo-EM analysis of the TAP transporter.

    Science.gov (United States)

    Oldham, Michael L; Hite, Richard K; Steffen, Alanna M; Damko, Ermelinda; Li, Zongli; Walz, Thomas; Chen, Jue

    2016-01-28

    Cellular immunity against viral infection and tumour cells depends on antigen presentation by major histocompatibility complex class I (MHC I) molecules. Intracellular antigenic peptides are transported into the endoplasmic reticulum by the transporter associated with antigen processing (TAP) and then loaded onto the nascent MHC I molecules, which are exported to the cell surface and present peptides to the immune system. Cytotoxic T lymphocytes recognize non-self peptides and program the infected or malignant cells for apoptosis. Defects in TAP account for immunodeficiency and tumour development. To escape immune surveillance, some viruses have evolved strategies either to downregulate TAP expression or directly inhibit TAP activity. So far, neither the architecture of TAP nor the mechanism of viral inhibition has been elucidated at the structural level. Here we describe the cryo-electron microscopy structure of human TAP in complex with its inhibitor ICP47, a small protein produced by the herpes simplex virus I. Here we show that the 12 transmembrane helices and 2 cytosolic nucleotide-binding domains of the transporter adopt an inward-facing conformation with the two nucleotide-binding domains separated. The viral inhibitor ICP47 forms a long helical hairpin, which plugs the translocation pathway of TAP from the cytoplasmic side. Association of ICP47 precludes substrate binding and prevents nucleotide-binding domain closure necessary for ATP hydrolysis. This work illustrates a striking example of immune evasion by persistent viruses. By blocking viral antigens from entering the endoplasmic reticulum, herpes simplex virus is hidden from cytotoxic T lymphocytes, which may contribute to establishing a lifelong infection in the host. PMID:26789246

  17. Transport and Mechanical Characteristics of Corrosion-Inhibited High- Strength Self-Compacting Concrete

    Directory of Open Access Journals (Sweden)

    Marva Blankson

    2015-11-01

    Full Text Available This paper is on the study of traditional silica fume (SG self-compacting concrete (SCC samples that was made as control and then incorporated with carboxylic inhibitor (SM to study the transport, rheological and mechanical responses of the inhibited samples. Comparison with the respective SG control, showed that the carboxylic inhibitor resulted in the reduction of the homogeneity of the SM samples and there was the development of flaws that could have contributed to the reduction in strength of the SM samples. When the concentration of the inhibitor was increased from the basic content to 100% higher, there was a noticeable increase in the chloride migration resistance of the SM samples. The study also showed that the transit time of the ultrasonic pulse that was transmitted was slower in the carboxylic inhibited-samples.

  18. Reaction mechanisms in transport theories: a test of the nuclear effective interaction

    CERN Document Server

    Colonna, M; Di Toro, M; Frecus, B; Zhang, Y X

    2012-01-01

    We review recent results concerning collective excitations in neutron-rich systems and reactions between charge asymmetric systems at Fermi energies. Solving numerically self-consistent transport equations for neutrons and protons with specific initial conditions, we explore the structure of the different dipole vibrations in the $^{132}Sn$ system and investigate their dependence on the symmetry energy. We evidence the existence of a distinctive collective mode, that can be associated with the Pygmy Dipole Resonance, with an energy well below the standard Giant Dipole Resonance and isoscalar-like character, i.e. very weakly dependent on the isovector part of the nuclear effective interaction. At variance, the corresponding strength is rather sensitive to the behavior of the symmetry energy below saturation, which rules the number of excess neutrons in the nuclear surface. In reactions between charge asymmetric systems at Fermi energies, we investigate the interplay between dissipation mechanisms and isospin e...

  19. Single-vesicle imaging reveals different transport mechanisms between glutamatergic and GABAergic vesicles.

    Science.gov (United States)

    Farsi, Zohreh; Preobraschenski, Julia; van den Bogaart, Geert; Riedel, Dietmar; Jahn, Reinhard; Woehler, Andrew

    2016-02-26

    Synaptic transmission is mediated by the release of neurotransmitters, which involves exo-endocytotic cycling of synaptic vesicles. To maintain synaptic function, synaptic vesicles are refilled with thousands of neurotransmitter molecules within seconds after endocytosis, using the energy provided by an electrochemical proton gradient. However, it is unclear how transmitter molecules carrying different net charges can be efficiently sequestered while maintaining charge neutrality and osmotic balance. We used single-vesicle imaging to monitor pH and electrical gradients and directly showed different uptake mechanisms for glutamate and γ-aminobutyric acid (GABA) operating in parallel. In contrast to glutamate, GABA was exchanged for protons, with no other ions participating in the transport cycle. Thus, only a few components are needed to guarantee reliable vesicle filling with different neurotransmitters. PMID:26912364

  20. Mechanisms of molecular transport through the urea channel of Helicobacter pylori

    Science.gov (United States)

    McNulty, Reginald; Ulmschneider, Jakob P.; Luecke, Hartmut; Ulmschneider, Martin B.

    2013-12-01

    Helicobacter pylori survival in acidic environments relies on cytoplasmic hydrolysis of gastric urea into ammonia and carbon dioxide, which buffer the pathogen’s periplasm. Urea uptake is greatly enhanced and regulated by HpUreI, a proton-gated inner membrane channel protein essential for gastric survival of H. pylori. The crystal structure of HpUreI describes a static snapshot of the channel with two constriction sites near the center of the bilayer that are too narrow to allow passage of urea or even water. Here we describe the urea transport mechanism at atomic resolution, revealed by unrestrained microsecond equilibrium molecular dynamics simulations of the hexameric channel assembly. Two consecutive constrictions open to allow conduction of urea, which is guided through the channel by interplay between conserved residues that determine proton rejection and solute selectivity. Remarkably, HpUreI conducts water at rates equivalent to aquaporins, which might be essential for efficient transport of urea at small concentration gradients.

  1. The extreme mobility of debris avalanches: A new model of transport mechanism

    Science.gov (United States)

    Perinotto, Hlne; Schneider, Jean-Luc; Bachlery, Patrick; Le Bourdonnec, Franois-Xavier; Famin, Vincent; Michon, Laurent

    2015-12-01

    Large rockslide-debris avalanches, resulting from flank collapses that shape volcanoes and mountains on Earth and other object of the solar system, are rapid and dangerous gravity-driven granular flows that travel abnormal distances. During the last 50 years, numerous physical models have been put forward to explain their extreme mobility. The principal models are based on fluidization, lubrication, or dynamic disintegration. However, these processes remain poorly constrained. To identify precisely the transport mechanisms during debris avalanches, we examined morphometric (fractal dimension and circularity), grain size, and exoscopic characteristics of the various types of particles (clasts and matrix) from volcanic debris avalanche deposits of La Runion Island (Indian Ocean). From these data we demonstrate for the first time that syn-transport dynamic disintegration continuously operates with the increasing runout distance from the source down to a grinding limit of 500 m. Below this limit, the particle size reduction exclusively results from their attrition by frictional interactions. Consequently, the exceptional mobility of debris avalanches may be explained by the combined effect of elastic energy release during the dynamic disintegration of the larger clasts and frictional reduction within the matrix due to interactions between the finer particles.

  2. Solute transport in fractured media - The important mechanisms for performance assessment

    International Nuclear Information System (INIS)

    The most important mechanisms that control the release of contaminants from a repository for nuclear or chemical waste have been studied. For the time scale of interest for the disposal of nuclear or even chemical waste, diffusion into the rock matrix is an important factor which retards and dilutes the contaminants. It is found that the water flow-rate distribution and the flow-wetted surface are the entities that primarily determine the solute transport. If the diffusion in the rock matrix is negligible, the solute transport is determined by the water flow-rate and the flow porosity. This is shown by simulations using analytical solutions obtained for simple geometries, such as the flow in a fracture or a channel. Similar results are obtained for more complex systems, such as flow in a fracture with variable aperture and through a network of channels. It is also found that the use of a retardation factor relating the travel times of interacting and noninteracting solutes is inappropriate and may be misleading. 11 refs, 9 figs, 1 tab

  3. Mechanism for transport of ivermectin to the stratum corneum in rats.

    Science.gov (United States)

    Miyajima, Atsushi; Kigure, Akira; Anata, Taichi; Hirota, Takashi

    2015-12-01

    Ivermectin (IVM) is used as an oral medication for scabies, a skin infection caused by a mite, sarcoptes scabiei, which parasitizes in the stratum corneum. After oral administration IVM is absorbed from the intestine, and finally distributed to the stratum corneum to eliminate the mites. However its transport mechanism remains unclear. A pharmacokinetic study was performed using hairless Wistar Yagi (HWY) rats, which have no or atrophied sebaceous glands, and Wistar rats as a reference. After oral administration of IVM to both groups, the area under the concentration-time curve of IVM in the dermis and epidermis (dermis-epidermis) of HWY rats were about 60% lower than that of Wistar rats, even though the plasma concentration profiles were comparable in both groups. In addition at 12 h after the administration, IVM concentration in the outer stratum corneum, the shallower layer of the dermis-epidermis, was higher compared to that in the deeper layer. In the dermis-epidermis of the skin from various locations, the concentrations of IVM and squalene, the latter of which is secreted to the skin surface via the sebaceous gland, were positively well correlated. Those results suggest that IVM is transported to the stratum corneum via the sebaceous glands. PMID:26613804

  4. Gamma ray attenuation studies of interception from Sitka spruce: some evidence for an additional transport mechanism

    International Nuclear Information System (INIS)

    Various forest canopy characteristics of stands of Sitka spruce (Picea sitchensis (Bong.) Carr.), including canopy density, the aerodynamic resistance to the transfer of water vapor, and the rates of change of drainage and evaporation of water with respect to canopy storage, were investigated using direct measurements of canopy mass and water storage. The measurements, made at sites located in Wales and Scotland, utilized the attenuation of a horizontal beam of gamma rays which was arranged to scan through the canopy at different levels. The aerodynamic resistance to the transport of water vapor from the canopy to a reference level 5 m above mean tree height was found to be consistent with the value of 3.5 s m−1, determined from earlier modeling studies (I. R. Calder, 1977). This value is, however, lower and shows less wind speed dependence than would be expected from conventional formulae which are based on eddy diffusion theory and tree height. The possibility of explaining these discrepancies in terms of an additional transport mechanism involving large-scale eddies is discussed

  5. Effects of hydrophobic aggregation on the charge transport mechanism of quaternary ammonium ionic liquids

    Science.gov (United States)

    Griffin, Philip; Holt, Adam; Wang, Yangyang; Novikov, Vladimir; Sangoro, Joshua; Sokolov, Alexei

    2014-03-01

    Aprotic quaternary ammonium ionic liquids (ILs) are an important class of ILs due to their large electrochemical window and hydrophobicity. However, many of these ILs suffer from relatively low conductivity at room temperature which limits their use in electrochemical applications. In order to understand the nature of this low conductivity and its relation to the chemical structure of the alkyl ammonium cation, we have measured the charge transport properties and structural dynamics of the room temperature ionic liquid methyltrioctylammonium bistriflimide [m3oa][ntf2] over a broad temperature range using dielectric spectroscopy, dynamic light scattering, rheology, and pulsed field gradient nuclear magnetic resonance. We demonstrate that the low values of dc conductivity are due to the combined effects of significantly reduced ion mobility as well as reduced free ion concentration relative to other types of ILs. Secondly we find evidence for a mesoscopic scale structural relaxation process that we attribute to the reorientational motion of nanometer sized alkyl nanodomains. These two findings indicate that hydrophobic aggregation plays an important role in the charge transport mechanism of aprotic ammonium ionic liquids with long aliphatic side chains.

  6. Embedding a Multi-agents Collaboration Mechanism into the Hybrid Middleware of an Intelligent Transportation System

    Directory of Open Access Journals (Sweden)

    Huan-Chao Keh

    2011-01-01

    Full Text Available Even if wireless networks and mobile computing technologies have comprehensively developed in recent years. Letting people extract information anywhere at anytime is the goal of this development. But in the telematics domain, the drivers can obtain road information through radio or certain in-car equipment, there is still a wide gap with regard to the synchronization of this information with actual road conditions. In the absence of adequate information, drivers often react to conditions with behaviors that do not contribute to their own driving goals but rather cause more complicated traffic conditions. Therefore, this study employs a process known as multi-agent collaboration. Information exchanged between the features and established mutual communication and collaboration mechanisms is applied in Intelligent Transportation Systems (ITS. By allowing drivers to have distributed communication with other vehicles to share driving information, collect information and/or submit their own reasoned driving advice to other drivers, many traffic situations could effectively be improved and the efficiency of the computing processes could be improved through distributed communication. This study proposes an architecture design for middleware that includes vehicle information, navigation, announcements and communication which could prove to be a more convenient and efficient intelligent transportation system.

  7. Catecholamine transport in cultured bovine adrenal medullary cells: kinetics and mechanism

    International Nuclear Information System (INIS)

    In primary cultures of bovine adrenomedullary cells, catecholamine uptake was found to be a saturable process exhibiting Michaelis-Menten kinetics with an apparent K/sub m/ for 1-norepinephrine of 0.5 μM. Radiolabeled catecholamines were employed to study the general characteristics and kinetic properties of catecholamine transport in cultured adrenomedullary cells. This process was found to be temperature, energy and Na+-dependent. In addition, uptake required the presence of extracellular Cl-, K+, and divalent cation such as Mn2+, Ca2+, or Mg2+. Agents that induce Ca2+-dependent, exocytotic secretion of catecholamines from these cells had significant inhibitory effects on catecholamine uptake. The secretagogues, nicotine, veratridine and elevated extracellular K+ concentrations, were all found to inhibit norepinephrine uptake. The inhibitory effects of the secretagogues could be fully demonstrated in the absence of catecholamine secretion. Investigation into the mechanism of catecholamine transport was pursued by measuring the effects of various catecholamine altering conditions or agents on the cellular membrane potential and/or the inwardly directed Na+ concentration gradient. Changes in the membrane potential were determined biochemically using tetraphenylphosphonium ion distribution, whereas changes in the Na+-gradient were assessed using 22Na+ distribution

  8. Solute transport and storage mechanisms in wetlands of the Everglades, south Florida

    Science.gov (United States)

    Harvey, Judson W.; Saiers, James E.; Newlin, Jessica T.

    2005-05-01

    Solute transport and storage processes in wetlands play an important role in biogeochemical cycling and in wetland water quality functions. In the wetlands of the Everglades, there are few data or guidelines to characterize transport through the heterogeneous flow environment. Our goal was to conduct a tracer study to help quantify solute exchange between the relatively fast flowing water in the open part of the water column and much more slowly moving water in thick floating vegetation and in the pore water of the underlying peat. We performed a tracer experiment that consisted of a constant-rate injection of a sodium bromide (NaBr) solution for 22 hours into a 3 m wide, open-ended flume channel in Everglades National Park. Arrival of the bromide tracer was monitored at an array of surface water and subsurface samplers for 48 hours at a distance of 6.8 m downstream of the injection. A one-dimensional transport model was used in combination with an optimization code to identify the values of transport parameters that best explained the tracer observations. Parameters included dimensions and mass transfer coefficients describing exchange with both short (hours) and longer (tens of hours) storage zones as well as the average rates of advection and longitudinal dispersion in the open part of the water column (referred to as the ``main flow zone''). Comparison with a more detailed set of tracer measurements tested how well the model's storage zones approximated the average characteristics of tracer movement into and out of the layer of thick floating vegetation and the pore water in the underlying peat. The rate at which the relatively fast moving water in the open water column was exchanged with slowly moving water in the layer of floating vegetation and in sediment pore water amounted to 50 and 3% h-1, respectively. Storage processes decreased the depth-averaged velocity of surface water by 50% relative to the water velocity in the open part of the water column. As a result, flow measurements made with other methods that only work in the open part of the water column (e.g., acoustic Doppler) would have overestimated the true depth-averaged velocity by a factor of 2. We hypothesize that solute exchange and storage in zones of floating vegetation and peat pore water increase contact time of solutes with biogeochemically active surfaces in this heterogeneous wetland environment.

  9. Helium solubility in mica and mechanisms for deep transport of noble gases in subduction zones

    Science.gov (United States)

    Jackson, C.; Parman, S. W.; Kelley, S. P.; Cooper, R. F.

    2012-12-01

    We have experimentally determined helium solubility in mica to explore possible transport mechanisms of noble gases in subduction zones. Helium solubility in single crystals of muscovite and F-phlogopite investigated is relatively high, ~1 [He]/PHe (ppm/kbar). This solubility is approximately two orders of magnitude greater than values recently measured for olivine [1], and similar to values recently measured for amphibole with a low density of unoccupied ring sites [2]. Helium was dissolved into the micas by subjecting them to a high pressure noble gas atmosphere (1.26-1.48 He-Ne-Ar kbar) at moderate temperatures (450-700 C), allowing the micas to diffusively equilibrate with the imposed helium fugacity. Diffusion of Ne and Ar is too slow in both micas at the explored conditions to quantify their solubility. Experiments were conducted using a TZM gas pressure medium apparatus (Brown University). Analysis was completed by noble gas LA-MS (Open University, UK). Muscovite (dioctehedral) and F-phlogopite (trioctehedral) represent the two basic structural groups of micas, suggesting micas stabilized at higher pressures and temperatures, such as phengite, can provide a relatively deep transport mechanism for noble gases delivered to subduction zones. Thus, phengite may play a role in explaining atmospheric signatures in mantle derived noble gases [e.g.3,4]. 1. Heber, V. S., Brooker, R. A., Kelley, S. P. & Wood, B. J., GCA, 71, 1041-1061 2. Jackson C.R.M, Kelley S.P., Parman S.W., Cooper R.F., Goldschmidt 2012 Abstract 3. Holland, G. & Ballentine, C. J., Nature 441, 186-191 4. Mukhopadhyay, S.. Nature 486, 101-104

  10. Ceruloplasmin ferroxidase activity stimulates cellular iron uptake by a trivalent cation-specific transport mechanism

    Science.gov (United States)

    Attieh, Z. K.; Mukhopadhyay, C. K.; Seshadri, V.; Tripoulas, N. A.; Fox, P. L.

    1999-01-01

    The balance required to maintain appropriate cellular and tissue iron levels has led to the evolution of multiple mechanisms to precisely regulate iron uptake from transferrin and low molecular weight iron chelates. A role for ceruloplasmin (Cp) in vertebrate iron metabolism is suggested by its potent ferroxidase activity catalyzing conversion of Fe2+ to Fe3+, by identification of yeast copper oxidases homologous to Cp that facilitate high affinity iron uptake, and by studies of "aceruloplasminemic" patients who have extensive iron deposits in multiple tissues. We have recently shown that Cp increases iron uptake by cultured HepG2 cells. In this report, we investigated the mechanism by which Cp stimulates cellular iron uptake. Cp stimulated the rate of non-transferrin 55Fe uptake by iron-deficient K562 cells by 2-3-fold, using a transferrin receptor-independent pathway. Induction of Cp-stimulated iron uptake by iron deficiency was blocked by actinomycin D and cycloheximide, consistent with a transcriptionally induced or regulated transporter. Cp-stimulated iron uptake was completely blocked by unlabeled Fe3+ and by other trivalent cations including Al3+, Ga3+, and Cr3+, but not by divalent cations. These results indicate that Cp utilizes a trivalent cation-specific transporter. Cp ferroxidase activity was required for iron uptake as shown by the ineffectiveness of two ferroxidase-deficient Cp preparations, copper-deficient Cp and thiomolybdate-treated Cp. We propose a model in which iron reduction and subsequent re-oxidation by Cp are essential for an iron uptake pathway with high ion specificity.

  11. Generation and transport mechanisms of chemical species by a post-discharge flow for inactivation of bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Takehiko [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Ochiai, Shiroh [Graduate School of Engineering, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Urayama, Takuya [Adtec Plasma Technology Co Ltd, 5-6-10 Hikino-chou, Fukuyama 721-0942 (Japan)], E-mail: sato@ifs.tohoku.ac.jp

    2009-11-15

    A post-discharge flow that is formed downstream of a microwave argon plasma in atmospheric air was investigated to clarify the generation and transport of chemical species, which are considered to result in the inactivation of bacteria. The flow, which is characterized by ultra-weak emission, can be visualized using an optical analysis system. This visualized jet-like flow forms downstream of the nozzle exit, and then, as the gas temperature is 877 K at the center of the nozzle exit, the main flow travels upstream around the quartz tube due to buoyancy, the reason being that the temperature decreases to room temperature at 30 mm downstream. It was clarified that excited argon atoms, molecular nitrogen (N{sub 2} second positive system) and OH radicals were generated in the post-discharge flow, subsequent to which NO{sub 2} and ions with a number density of 10{sup 6} counts cm{sup -3} were transported downstream below the main flow. These results imply that most of the heat and chemical species were transported by convective transport of the main flow, but that a small amount of chemically active species and ions might have been transported further downstream by diffusive transport, these species being considered to result in an inactivation effect on bacteria.

  12. Generation and transport mechanisms of chemical species by a post-discharge flow for inactivation of bacteria

    International Nuclear Information System (INIS)

    A post-discharge flow that is formed downstream of a microwave argon plasma in atmospheric air was investigated to clarify the generation and transport of chemical species, which are considered to result in the inactivation of bacteria. The flow, which is characterized by ultra-weak emission, can be visualized using an optical analysis system. This visualized jet-like flow forms downstream of the nozzle exit, and then, as the gas temperature is 877 K at the center of the nozzle exit, the main flow travels upstream around the quartz tube due to buoyancy, the reason being that the temperature decreases to room temperature at 30 mm downstream. It was clarified that excited argon atoms, molecular nitrogen (N2 second positive system) and OH radicals were generated in the post-discharge flow, subsequent to which NO2 and ions with a number density of 106 counts cm-3 were transported downstream below the main flow. These results imply that most of the heat and chemical species were transported by convective transport of the main flow, but that a small amount of chemically active species and ions might have been transported further downstream by diffusive transport, these species being considered to result in an inactivation effect on bacteria.

  13. Main aspects in licensing of a type B(U) package design for the transport of 12.95 PBq of cobalt 60

    International Nuclear Information System (INIS)

    This paper points out the relevant technical issues related to the licensing process, of a type B(U) package design, with cylindrical form and 9.3 ton mass, approved by the Argentine Competent Authority for the transport of 12.95 PBq of cobalt 60 as special form radioactive material. It is briefly described the heat transfer analysis, the structural performance under impulsive loads and the shielding calculation under both normal and accidental conditions of transport, as well as the comparative analysis of the results obtained from design, pre-operational tests and independent evaluation performed by the Argentine Competent Authority to verify the compliance with the Regulations for the Safe Transport of Radioactive Material of the International Atomic Energy Agency. (author). 14 refs., 1 fig., tabs

  14. Na+-stimulated phosphate uptake system in Synechocystis sp. PCC 6803 with Pst1 as a main transporter

    OpenAIRE

    Burut-Archanai Surachet; Eaton-Rye Julian J; Incharoensakdi Aran

    2011-01-01

    Abstract Background Most living cells uptake phosphate, an indispensable nutrient for growth from their natural environment. In Synechocystis sp. PCC 6803, the cells lack phosphate-inorganic transport (Pit) system but contain two phosphate-specific transport (Pst) systems, Pst1 and Pst2. We investigated the kinetics of Pi uptake of these two Pst systems by constructing the two mutants, ΔPst1 and ΔPst2, and comparing their kinetic properties with those of the wild-type cells under both Pi-suff...

  15. Transport in semiconductor nanowire superlattices described by coupled quantum mechanical and kinetic models.

    Science.gov (United States)

    Alvaro, M; Bonilla, L L; Carretero, M; Melnik, R V N; Prabhakar, S

    2013-08-21

    In this paper we develop a kinetic model for the analysis of semiconductor superlattices, accounting for quantum effects. The model consists of a Boltzmann-Poisson type system of equations with simplified Bhatnagar-Gross-Krook collisions, obtained from the general time-dependent Schrdinger-Poisson model using Wigner functions. This system for superlattice transport is supplemented by the quantum mechanical part of the model based on the Ben-Daniel-Duke form of the Schrdinger equation for a cylindrical superlattice of finite radius. The resulting energy spectrum is used to characterize the Fermi-Dirac distribution that appears in the Bhatnagar-Gross-Krook collision, thereby coupling the quantum mechanical and kinetic parts of the model. The kinetic model uses the dispersion relation obtained by the generalized Kronig-Penney method, and allows us to estimate radii of quantum wire superlattices that have the same miniband widths as in experiments. It also allows us to determine more accurately the time-dependent characteristics of superlattices, in particular their current density. Results, for several experimentally grown superlattices, are discussed in the context of self-sustained coherent oscillations of the current density which are important in an increasing range of current and potential applications. PMID:23877936

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

    International Nuclear Information System (INIS)

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

  17. Emergency Situation Prediction Mechanism: A Novel Approach for Intelligent Transportation System Using Vehicular Ad Hoc Networks.

    Science.gov (United States)

    Ganeshkumar, P; Gokulakrishnan, P

    2015-01-01

    In Indian four-lane express highway, millions of vehicles are travelling every day. Accidents are unfortunate and frequently occurring in these highways causing deaths, increase in death toll, and damage to infrastructure. A mechanism is required to avoid such road accidents at the maximum to reduce the death toll. An Emergency Situation Prediction Mechanism, a novel and proactive approach, is proposed in this paper for achieving the best of Intelligent Transportation System using Vehicular Ad Hoc Network. ESPM intends to predict the possibility of occurrence of an accident in an Indian four-lane express highway. In ESPM, the emergency situation prediction is done by the Road Side Unit based on (i) the Status Report sent by the vehicles in the range of RSU and (ii) the road traffic flow analysis done by the RSU. Once the emergency situation or accident is predicted in advance, an Emergency Warning Message is constructed and disseminated to all vehicles in the area of RSU to alert and prevent the vehicles from accidents. ESPM performs well in emergency situation prediction in advance to the occurrence of an accident. ESPM predicts the emergency situation within 0.20 seconds which is comparatively less than the statistical value. The prediction accuracy of ESPM against vehicle density is found better in different traffic scenarios. PMID:26065014

  18. Preliminary investigation of gas transport mechanism in a H+ irradiated polyimide-ceramic composite membrane

    International Nuclear Information System (INIS)

    Recent research by our group indicated that ion beam irradiation can simultaneously increase the gas permeability and permselectivity of polymeric membrane materials. The temperature dependence of the gas permeation properties of a H+ ion irradiated polyimide-ceramic composite membrane was investigated to address issues of changes in the gas transport mechanism in irradiated polymers. As was seen for glassy polymers, the temperature dependence of the permeation properties of the irradiated membrane followed an Arrhenius type relationship. Both the activation energy (Ep) for gas permeation and the pre-exponential factor (P0) of the irradiated polymer were greater than the values of the unmodified bulk polymer. Large increases in the pre-exponential factor of the irradiated sample for small size gas molecules (He, O2 and CO2) combined with the dominant contribution of the pre-exponential factor to the permselectivity for several gas pairs (He/CH4, O2/N2, and CO2/CH4) implied that the irradiated sample had a different permeation mechanism than the bulk material

  19. “Green” fuel tax on private transportation services and subsidies to electric energy. A model-based assessment for the main European countries

    International Nuclear Information System (INIS)

    This paper evaluates the environmental and macroeconomic implications for France, Germany, Italy and Spain of taxing motor vehicle fuels for private transportation, a sector not subject to the Emissions Trading System, so as to reduce taxes on electricity consumption and increase subsidies to renewable sources of electricity generation. The assessment is based on a dynamic general equilibrium model calibrated for each of the four countries. The results suggest that the measures posited will reduce carbon dioxide emissions in the transportation sector and favor the development of electricity generation from renewable sources, thus limiting the growth of emissions from electricity generation. The measures do not jeopardize economic activity. The results are robust whether implementation is unilateral in one country or simultaneous throughout the EU. - Highlights: • The European Union's Agenda 2020 calls for member countries to reduce greenhouse gas emissions and increase renewable energy. • We evaluate implications in the EU of taxing fuels for private transportation, reducing taxes on electricity and increase subsidies to renewable sources of electricity. • The assessment is based on a dynamic general equilibrium model. • The measures reduce emissions, in particular in the transportation sector, favor electricity generation from renewable sources and do not jeopardize economic activity

  20. First-principles Study on the Charge Transport Mechanism of Lithium Sulfide (Li2 S) in Lithium-Sulfur Batteries.

    Science.gov (United States)

    Kim, B S Do-Hoon; Lee, M S Byungju; Park, Kyu-Young; Kang, Kisuk

    2016-04-20

    The lithium-sulfur chemistry is regarded as a promising candidate for next-generation battery systems because of its high specific energy (1675 mA h g(-1) ). Although issues such as low cycle stability and power capability of the system remain to be addressed, extensive research has been performed experimentally to resolve these problems. Attaining a fundamental understanding of the reaction mechanism and its reaction product would further spur the development of lithium-sulfur batteries. Here, we investigated the charge transport mechanism of lithium sulfide (Li2 S), a discharge product of conventional lithium-sulfur batteries using first-principles calculations. Our calculations indicate that the major charge transport is governed by the lithium-ion vacancies among various possible charge carriers. Furthermore, the large bandgap and low concentration of electron polarons indicate that the electronic conduction negligibly contributes to the charge transport mechanism in Li2 S. PMID:26928985

  1. The allosteric regulatory mechanism of the Escherichia coli MetNI methionine ATP binding cassette (ABC) transporter.

    Science.gov (United States)

    Yang, Janet G; Rees, Douglas C

    2015-04-01

    The MetNI methionine importer of Escherichia coli, an ATP binding cassette (ABC) transporter, uses the energy of ATP binding and hydrolysis to catalyze the high affinity uptake of D- and L-methionine. Early in vivo studies showed that the uptake of external methionine is repressed by the level of the internal methionine pool, a phenomenon termed transinhibition. Our understanding of the MetNI mechanism has thus far been limited to a series of crystal structures in an inward-facing conformation. To understand the molecular mechanism of transinhibition, we studied the kinetics of ATP hydrolysis using detergent-solubilized MetNI. We find that transinhibition is due to noncompetitive inhibition by L-methionine, much like a negative feedback loop. Thermodynamic analyses revealed two allosteric methionine binding sites per transporter. This quantitative analysis of transinhibition, the first to our knowledge for a structurally defined transporter, builds upon the previously proposed structurally based model for regulation. This mechanism of regulation at the transporter activity level could be applicable to not only ABC transporters but other types of membrane transporters as well. PMID:25678706

  2. Main findings

    International Nuclear Information System (INIS)

    Licensing regimes vary from country to country. When the license regime involves several regulators and several licenses, this may lead to complex situations. Identifying a leading organisation in charge of overall coordination including preparation of the licensing decision is a useful practice. Also, if a stepwise licensing process is implemented, it is important to fix in legislation decisions and/or time points and to identify the relevant actors. There is considerable experience in civil and mining engineering that can be applied when constructing a deep geological disposal facility. Specific challenges are, however, the minimization of disturbances to the host rock and the understanding of its long-term behavior. Construction activities may affect the geo-hydraulic and geochemical properties of the various system components which are important safety features of the repository system. Clearly defined technical specifications and an effective quality management plan are important in ensuring successful repository implementation which is consistent with safety requirements. Monitoring plan should also be defined in advance. The regulatory organization should prepare itself to the licensing review before construction by allocating sufficient resources. It should increase its competence, e.g., by interacting early with the implementer and through its own R and D. This will allow the regulator to define appropriate technical conditions associated to the construction license and to elaborate a relevant inspection plan of the construction work. After construction, obtaining the operational license is the most important and crucial step. Main challenges include (a) establishing sufficient confidence so that the methods for closing the individual disposal units comply with the safety objectives and (b) addressing the issue of ageing of materials during a 50-100 years operational period. This latter challenge is amplified when reversibility/retrievability is required. Managing concomitant construction of new galleries with continuing operation and/or closure in the existing galleries remains as another challenge. There is a need, during the project, to address targets very different in nature and which may potentially compete with each other. Alternative solutions are typically compared and evaluated with a view to lower potential impacts and risks to workers, people and the environment in the short and the long term to as low as reasonably practicable. This is often called 'radiological optimisation'. In repository development, the set of target functions can be much broader, blurring the meaning of 'optimisation'. The visibility and importance to optimisation for licensing varies from country to country, and it may take different names

  3. Dysregulation of glutamine transporter SNAT1 in Rett syndrome microglia: a mechanism for mitochondrial dysfunction and neurotoxicity.

    Science.gov (United States)

    Jin, Lee-Way; Horiuchi, Makoto; Wulff, Heike; Liu, Xiao-Bo; Cortopassi, Gino A; Erickson, Jeffrey D; Maezawa, Izumi

    2015-02-11

    Rett syndrome (RTT) is an autism spectrum disorder caused by loss-of-function mutations in the gene encoding MeCP2, an epigenetic modulator that binds the methyl CpG dinucleotide in target genes to regulate transcription. Previously, we and others reported a role of microglia in the pathophysiology of RTT. To understand the mechanism of microglia dysfunction in RTT, we identified a MeCP2 target gene, SLC38A1, which encodes a major glutamine transporter (SNAT1), and characterized its role in microglia. We found that MeCP2 acts as a microglia-specific transcriptional repressor of SNAT1. Because glutamine is mainly metabolized in the mitochondria, where it is used as an energy substrate and a precursor for glutamate production, we hypothesize that SNAT1 overexpression in MeCP2-deficient microglia would impair the glutamine homeostasis, resulting in mitochondrial dysfunction as well as microglial neurotoxicity because of glutamate overproduction. Supporting this hypothesis, we found that MeCP2 downregulation or SNAT1 overexpression in microglia resulted in (1) glutamine-dependent decrease in microglial viability, which was corroborated by reduced microglia counts in the brains of MECP2 knock-out mice; (2) proliferation of mitochondria and enhanced mitochondrial production of reactive oxygen species; (3) increased oxygen consumption but decreased ATP production (an energy-wasting state); and (4) overproduction of glutamate that caused NMDA receptor-dependent neurotoxicity. The abnormalities could be rectified by mitochondria-targeted expression of catalase and a mitochondria-targeted peptide antioxidant, Szeto-Schiller 31. Our results reveal a novel mechanism via which MeCP2 regulates bioenergetic pathways in microglia and suggest a therapeutic potential of mitochondria-targeted antioxidants for RTT. PMID:25673846

  4. Transport

    International Nuclear Information System (INIS)

    The decree ''RID'' of the 5. June 2001 concerns the rail transport of dangerous materials (RID), it replaces and abrogates the previous decree ''RID'' dating from the 6. December 1996 and all its successive modifying texts. This new decree ''RID'' aims at implementing in French law the amendment 2001 of the European RID regulations. This decree is composed of 2 parts, the first part contains the RID regulations itself and the second part concerns the transport of explosible materials and object that are usually rated in the class 1. (A.C.)

  5. Charge carrier transport mechanisms in perovskite CdTiO3 fibers

    International Nuclear Information System (INIS)

    Electrical transport properties of electrospun cadmium titanate (CdTiO3) fibers have been investigated using ac and dc measurements. Air annealing of as spun fibers at 1000 °C yielded the single phase perovskite fibers having diameter ∼600 nm - 800 nm. Both the ac and dc electrical measurements were carried out at temperatures from 200 K – 420 K. The complex impedance plane plots revealed a single semicircular arc which indicates the interfacial effect due to grain boundaries of fibers. The dielectric properties obey the Maxwell-Wagner theory of interfacial polarization. In dc transport study at low voltages, data show Ohmic like behavior followed by space charge limited current (SCLC) with traps at higher voltages at all temperatures (200 K – 420 K). Trap density in our fibers system is Nt = 6.27 × 1017 /cm3. Conduction mechanism in the sample is governed by 3-D variable range hopping (VRH) from 200 K – 300 K. The localized density of states were found to be N(EF) = 5.51 × 1021 eV−1 cm−3 at 2 V. Other VRH parameters such as hopping distance (Rhop) and hopping energy (Whop) were also calculated. In the high temperature range of 320 K – 420 K, conductivity follows the Arrhenius law. The activation energy found at 2 V is 0.10 eV. Temperature dependent and higher values of dielectric constant make the perovskite CdTiO3 fibers efficient material for capacitive energy storage devices

  6. Theoretical analysis of selectivity mechanisms in molecular transport through channels and nanopores

    International Nuclear Information System (INIS)

    Selectivity is one of the most fundamental concepts in natural sciences, and it is also critically important in various technological, industrial, and medical applications. Although there are many experimental methods that allow to separate molecules, frequently they are expensive and not efficient. Recently, a new method of separation of chemical mixtures based on utilization of channels and nanopores has been proposed and successfully tested in several systems. However, mechanisms of selectivity in the molecular transport during the translocation are still not well understood. Here, we develop a simple theoretical approach to explain the origin of selectivity in molecular fluxes through channels. Our method utilizes discrete-state stochastic models that take into account all relevant chemical transitions and can be solved analytically. More specifically, we analyze channels with one and two binding sites employed for separating mixtures of two types of molecules. The effects of the symmetry and the strength of the molecular-pore interactions are examined. It is found that for one-site binding channels, the differences in the strength of interactions for two species drive the separation. At the same time, in more realistic two-site systems, the symmetry of interaction potential becomes also important. The most efficient separation is predicted when the specific binding site is located near the entrance to the nanopore. In addition, the selectivity is higher for large entrance rates into the channel. It is also found that the molecular transport is more selective for repulsive interactions than for attractive interactions. The physical-chemical origin of the observed phenomena is discussed

  7. Chalcopyrite solar cells: Formation of the buffer / absorber interface and related transport mechanisms

    International Nuclear Information System (INIS)

    Full text : It was investigated the chemistry and electronics as well as the related transport mechanisms of low-gap chalcopyrite Cu(In1-xGax)Se2- (CIGSe; Ga/(In+Ga) = 0.24) and wide-gap CuGaSe2- (CGSe; 0.94 ≤ Ga/Cu ≤ 1.39) based solar cells by addressing the following issues: (1) condition of the absorber surface, (2) condition of the buffer layer preparation, and (3) thermal annealing of the devices. The chemical structure is investigated by applying heavy-ion elastic recoil detection analysis (ERDA), non-destructive x-ray photoelectron spectroscopy (XPS) and x-ray emission spectroscopy (XES). The electronic structure is investigated by UV photoelectron spectroscopy (UPS) and Kelvin probe force microscopy (KPFM) in UHV (p ≤ 10-10 mbar). The device transport properties have been investigated by illumination- and temperature-dependent current-voltage [J(V,T)] measurements. As a result, for respective solar cells we find that independently from the absorber bulk composition the dominant recombination process takes place at the buffer/absorber interface. However, while in devices from near-stoichiometric absorbers a tunnelling enhanced interface recombination takes place competitively at CdS/CuGaSe2 - CdS/CuGa3Se5 interfaces, in solar cells from Ga-rich absorbers a dominant thermally activated Shockley-Read-Hall recombination via deep levels in the CuGa3Se5 layer occur at the buffer/absorber interface. Furthermore, it was found that the monotonic increase of the devices open circuit voltages is determined by the monotonic variation of the potential barrier of recombination

  8. Mechanism of Nitrate-N Transport in Surface Water and Groundwater in a Missourian Claypan Watershed

    Science.gov (United States)

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

    2014-12-01

    Nitrogen (N) fertilizer applications have resulted in widespread surface water and groundwater nitrate-N (NO3-N) contamination in the U.S. Corn Belt. However, the processes that control NO3-N concentrations in both surface water and groundwater were not well understood, particularly for claypan-dominated watersheds. The objective of this study was to understand the processes that control the transport of NO3-N in/from surface water and/to groundwater in Goodwater Creek Experimental Watershed (GCEW), a claypan-dominated watershed in north-central Missouri. The mean nitrate-N concentration in groundwater determined from more than 2000 samples collected during 1991 - 2004 was approximately three times that in stream water at GCEW. Despite the low hydraulic conductivity of the claypan soils, considerable NO3-N contamination of the glacial till aquifer occurred, with 38% of the wells exceeding 10 mg l-1. Groundwater recharge by preferential pathways through the claypan appeared to be the primary mechanism for NO3-N movement to the aquifer. In comparison, only 19-23% of sampled wells in non-claypan agricultural watersheds over the continental U.S. exceeded 10 mg l-1, suggesting that groundwater in GCEW appears to be more susceptible to NO3-N contamination than non-claypan watersheds. Using endmember mixing analysis based on conservative tracers, stream flow during the relatively low flow periods was primarily from surface runoff, shallow subsurface water and groundwater, with an average contribution of 25%, 44% and 31% from 2011 to 2014, respectively. Stable isotopic values of nitrate (d15N, d18O and D17O) also demonstrated that groundwater exerted a major control on nitrate concentrations in stream water. This information greatly improves our understanding of the processes that control NO3-N transport to the groundwater system of claypan-dominated watersheds.

  9. Charge carrier transport mechanisms in perovskite CdTiO3 fibers

    Directory of Open Access Journals (Sweden)

    Z. Imran

    2014-06-01

    Full Text Available Electrical transport properties of electrospun cadmium titanate (CdTiO3 fibers have been investigated using ac and dc measurements. Air annealing of as spun fibers at 1000 °C yielded the single phase perovskite fibers having diameter ∼600 nm - 800 nm. Both the ac and dc electrical measurements were carried out at temperatures from 200 K – 420 K. The complex impedance plane plots revealed a single semicircular arc which indicates the interfacial effect due to grain boundaries of fibers. The dielectric properties obey the Maxwell-Wagner theory of interfacial polarization. In dc transport study at low voltages, data show Ohmic like behavior followed by space charge limited current (SCLC with traps at higher voltages at all temperatures (200 K – 420 K. Trap density in our fibers system is Nt = 6.27 × 1017 /cm3. Conduction mechanism in the sample is governed by 3-D variable range hopping (VRH from 200 K – 300 K. The localized density of states were found to be N(EF = 5.51 × 1021 eV−1 cm−3 at 2 V. Other VRH parameters such as hopping distance (Rhop and hopping energy (Whop were also calculated. In the high temperature range of 320 K – 420 K, conductivity follows the Arrhenius law. The activation energy found at 2 V is 0.10 eV. Temperature dependent and higher values of dielectric constant make the perovskite CdTiO3 fibers efficient material for capacitive energy storage devices.

  10. Transport mechanisms in low-resistance ohmic contacts to p-InP formed by rapid thermal annealing

    DEFF Research Database (Denmark)

    Clausen, Thomas; Leistiko, Otto

    1993-01-01

    process is related to interdiffusion and compound formation between the metal elements and the InP. The onset of low specific contact resistance is characterized by a change in the dominant transport mechanism; from predominantly a combination of thermionic emission and field emission to purely thermionic......Thermionic emission across a very small effective Schottky barrier (0-0.2 eV) are reported as being the dominant transport process mechanism in very low-resistance ohmic contacts for conventional AuZn(Ni) metallization systems top-InP formed by rapid thermal annealing. The barrier modulation...

  11. Mechanism of lipid mobilization by the small intestine after transport blockade

    International Nuclear Information System (INIS)

    The nonionic detergent, Pluronic L-81 (L-81) has been shown to block the transport of intestinal mucosal triacylglycerol (TG) in chylomicrons. This results in large lipid masses within the enterocyte that are greater in diameter than chylomicrons. On removal of L-81, mucosal TG is rapidly mobilized and appears in the lymph. We questioned whether the blocked TG requires partial or complete hydrolysis before its transport. Rats were infused intraduodenally with [3H]glyceryl, [14C]oleoyl trioleate (TO) and 0.5 mg L-81/h for 8 h, followed by 120 mumol/h linoleate for 18 h. Mesenteric lymph was collected and analyzed for TG content and radioactivity. An HPLC method was developed to separate TG on the basis of its acyl group species. The assumed acyl group composition was confirmed by gas liquid chromatography analysis. TG lymphatic output was low for the first 8 h but increased to 52 mumol/h at the 11th h of infusion (3 h after stopping L-81). 38% of the infused TO was retained in the mucosa after the 8-h infusion. 95% of mucosal TG was TO, 92% of the radioactivity was in TG, and 2.4% of the 14C disintegrations per minute was in fatty acid. HPLC analysis of lymph at 6, 10, 12, and 14.5 h of infusion showed a progressive rise in TG composed of one linoleate and two oleates, to 39%; and in TG composed of two linoleates and one oleate to 20% at 14.5 h of infusion. On a mass basis, however, 80% of the TG acyl groups were oleate. 3H/14C ratios in the various TG acyl group species reflected the decrease in oleate. We conclude that first, unlike liver, most mucosal TG is not hydrolyzed before transport. The mechanism of how the large lipid masses present in mucosal cells after L-81 infusion are converted to the much smaller chylomicrons is unknown. Second, the concomitant infusion of linoleate did not impair lymph TG delivery after L-81 blockade

  12. Multi-Path Transportation Futures Study. Vehicle Characterization and Scenario Analyses: Main Text and Appendices A, B, C, D, and F

    Energy Technology Data Exchange (ETDEWEB)

    Plotkin, Steve [Argonne National Lab. (ANL), Argonne, IL (United States); Singh, Margaret [Argonne National Lab. (ANL), Argonne, IL (United States); Patterson, Phil [U.S. Dept. of Energy, Washington, DC (United States); Ward, Jake [U.S. Dept. of Energy, Washington, DC (United States); Wood, Frances [OnLocation Inc., Vienna, VA (United States); Kydes, Niko [OnLocation Inc., Vienna, VA (United States); Holte, John [OnLocation Inc., Vienna, VA (United States); Moore, Jim [TA Engineering, Inc., Catonsville, MD (United States); Miller, Grant [TA Engineering, Inc., Catonsville, MD (United States); Das, Sujit [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Greene, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2009-07-22

    This report provides details for Phase 2 of the Multi-Path Transportation Futures Study, which compares alternative ways to make significant reductions in oil use and carbon emissions from U.S. light vehicles to 2050. Phase I, completed in 2009, examined the full range of pathways of interest to EERE, with multiple scenarios aimed at revealing the issues and impacts associated with a national effort to reduce U.S. dependence on oil use in transportation. Phase 2 expanded the scope of the analysis by examining the interactive effects of multiple pathways on each other and on oil and feedstock prices, focusing far more on costs; and substantially increasing the number of metrics used to compare pathways and scenarios.

  13. An evaluation of perfomance management in the Department of Public Works, Roads and Transport of the North West Privince / S. E Maine

    OpenAIRE

    Maine, S E

    2014-01-01

    Effective performance management is vital in all public and private sectors and contributes to service delivery of the organisations. Research on public-sector performance management, however, points out challenges in the implementation of the systems and questions the effectiveness of policy tools for enhancing the governmental accountability. The Department of Public Works, Roads and Transport is a large institution and its vision is to provide successful infrastructure projects...

  14. Lipid transport function is the main target of oral oleoylethanolamide to reduce adiposity in high-fat-fed mice[S

    OpenAIRE

    Thabuis, Clémentine; Destaillats, Frédéric; Lambert, Didier M; Muccioli, Giulio G.; Maillot, Matthieu; Harach, Touafiq; Tissot-Favre, Delphine; Martin, Jean-Charles

    2011-01-01

    Abstract We evaluated the biological basis of reduced fat gain by oleoylethanolamide (OEA) in high-fat-fed mice and sought to determine how degradation of OEA affected its efficiency by comparing its effects to those of KDS-5104, a nonhydrolyzable lipid OEA analog. Mice were given OEA or KDS-5104 by the oral route (100 mg/kg body weight). Sixty-eight variables per mouse, describing six biological processes (lipid transport, lipogenesis, energy intake, energy expenditure, endocannabinoid signa...

  15. Oxygen transport in perovskite-type solid oxide fuel cell materials: insights from quantum mechanics.

    Science.gov (United States)

    Muoz-Garca, Ana B; Ritzmann, Andrew M; Pavone, Michele; Keith, John A; Carter, Emily A

    2014-11-18

    CONSPECTUS: Global advances in industrialization are precipitating increasingly rapid consumption of fossil fuel resources and heightened levels of atmospheric CO2. World sustainability requires viable sources of renewable energy and its efficient use. First-principles quantum mechanics (QM) studies can help guide developments in energy technologies by characterizing complex material properties and predicting reaction mechanisms at the atomic scale. QM can provide unbiased, qualitative guidelines for experimentally tailoring materials for energy applications. This Account primarily reviews our recent QM studies of electrode materials for solid oxide fuel cells (SOFCs), a promising technology for clean, efficient power generation. SOFCs presently must operate at very high temperatures to allow transport of oxygen ions and electrons through solid-state electrolytes and electrodes. High temperatures, however, engender slow startup times and accelerate material degradation. SOFC technologies need cathode and anode materials that function well at lower temperatures, which have been realized with mixed ion-electron conductor (MIEC) materials. Unfortunately, the complexity of MIECs has inhibited the rational tailoring of improved SOFC materials. Here, we gather theoretically obtained insights into oxygen ion conductivity in two classes of perovskite-type materials for SOFC applications: the conventional La1-xSrxMO3 family (M = Cr, Mn, Fe, Co) and the new, promising class of Sr2Fe2-xMoxO6 materials. Using density functional theory + U (DFT+U) with U-J values obtained from ab initio theory, we have characterized the accompanying electronic structures for the two processes that govern ionic diffusion in these materials: (i) oxygen vacancy formation and (ii) vacancy-mediated oxygen migration. We show how the corresponding macroscopic oxygen diffusion coefficient can be accurately obtained in terms of microscopic quantities calculated with first-principles QM. We find that the oxygen vacancy formation energy is a robust descriptor for evaluating oxide ion transport properties. We also find it has a direct relationship with (i) the transition metal-oxygen bond strength and (ii) the extent to which electrons left behind by the departing oxygen delocalize onto the oxygen sublattice. Design principles from our QM results may guide further development of perovskite-based MIEC materials for SOFC applications. PMID:24972154

  16. Multi-Drug Resistance Transporters and a Mechanism-Based Strategy for Assessing Risks of Pesticide Combinations to Honey Bees.

    Science.gov (United States)

    Guseman, Alex J; Miller, Kaliah; Kunkle, Grace; Dively, Galen P; Pettis, Jeffrey S; Evans, Jay D; vanEngelsdorp, Dennis; Hawthorne, David J

    2016-01-01

    Annual losses of honey bee colonies remain high and pesticide exposure is one possible cause. Dangerous combinations of pesticides, plant-produced compounds and antibiotics added to hives may cause or contribute to losses, but it is very difficult to test the many combinations of those compounds that bees encounter. We propose a mechanism-based strategy for simplifying the assessment of combinations of compounds, focusing here on compounds that interact with xenobiotic handling ABC transporters. We evaluate the use of ivermectin as a model substrate for these transporters. Compounds that increase sensitivity of bees to ivermectin may be inhibiting key transporters. We show that several compounds commonly encountered by honey bees (fumagillin, Pristine, quercetin) significantly increased honey bee mortality due to ivermectin and significantly reduced the LC50 of ivermectin suggesting that they may interfere with transporter function. These inhibitors also significantly increased honey bees sensitivity to the neonicotinoid insecticide acetamiprid. This mechanism-based strategy may dramatically reduce the number of tests needed to assess the possibility of adverse combinations among pesticides. We also demonstrate an in vivo transporter assay that provides physical evidence of transporter inhibition by tracking the dynamics of a fluorescent substrate of these transporters (Rhodamine B) in bee tissues. Significantly more Rhodamine B remains in the head and hemolymph of bees pretreated with higher concentrations of the transporter inhibitor verapamil. Mechanism-based strategies for simplifying the assessment of adverse chemical interactions such as described here could improve our ability to identify those combinations that pose significantly greater risk to bees and perhaps improve the risk assessment protocols for honey bees and similar sensitive species. PMID:26840460

  17. Computational modelling of thermo-mechanical and transport properties of carbon nanotubes

    International Nuclear Information System (INIS)

    Over the recent years, numerical modelling and computer-based simulation of the properties of carbon nanotubes have become the focal points of research in computational nano-science and its associated fields of computational condensed matter physics and materials modelling. Modelling of the mechanical, thermal and transport properties of nanotubes via numerical simulations forms the central part of this research, concerned with the nano-scale mechanics and nano-scale thermodynamics of nanotubes, and nano-scale adsorption, storage and flow properties in nanotubes. A review of these properties, obtained via computational modelling studies, is presented here. We first introduce the physics of carbon nanotubes, and then present the computational simulation tools that are appropriate for conducting a modelling study at the nano-scales. These include the molecular dynamics (MD), the Monte Carlo (MC), and the ab initio MD simulation methods. A complete range of inter-atomic potentials, of two-body and many-body varieties, that underlie all the modelling studies considered in this review is also given. Mechanical models from continuum-based elasticity theory that have been extensively employed in computing the energetics of nanotubes, or interpret the results from atomistic modelling, are presented and discussed. These include models based on the continuum theory of curved plates, shells, vibrating rods and bending beams. The validity of these continuum-based models has also been examined and the conditions under which they are applicable to nanotube modelling have been listed. Pertinent concepts from continuum theories of stress analysis are included, and the relevant methods for conducting the computation of the stress tensor, elastic constants and elastic modulii at the atomic level are also given. We then survey a comprehensive range of modelling studies concerned with the adsorption and storage of gases, and flow of fluids, in carbon nanotubes of various types. This is then followed by an extensive survey of the numerical modelling investigations that have addressed the mechanical and thermal properties of these structures. The survey of modelling studies is supplemented by reviews of experimental investigations, where appropriate, to help clarify their results

  18. Red blood cell transport mechanisms in polyester thread-based blood typing devices.

    Science.gov (United States)

    Nilghaz, Azadeh; Ballerini, David R; Guan, Liyun; Li, Lizi; Shen, Wei

    2016-02-01

    A recently developed blood typing diagnostic based on a polyester thread substrate has shown great promise for use in medical emergencies and in impoverished regions. The device is easy to use and transport, while also being inexpensive, accurate, and rapid. This study used a fluorescent confocal microscope to delve deeper into how red blood cells were behaving within the polyester thread-based diagnostic at the cellular level, and how plasma separation could be made to visibly occur on the thread, making it possible to identify blood type in a single step. Red blood cells were stained and the plasma phase dyed with fluorescent compounds to enable them to be visualised under the confocal microscope at high magnification. The mechanisms uncovered were in surprising contrast with those found for a similar, paper-based method. Red blood cell aggregates did not flow over each other within the thread substrate as expected, but suffered from a restriction to their flow which resulted in the chromatographic separation of the RBCs from the liquid phase of the blood. It is hoped that these results will lead to the optimisation of the method to enable more accurate and sensitive detection, increasing the range of blood systems that can be detected. Graphical Abstract Agglutinated FITC stained A+ blood on anti-A antibody treated thread. Sheet like structures composed of agglutinated RBCs can be seen, wrapped around fibres and occupying the spaces between them. PMID:26163133

  19. Transport-mechanisms in natural nucleate boiling in absence of external forces

    Energy Technology Data Exchange (ETDEWEB)

    Straub, Johannes [Technical University Munich, Faculty Mw. Thermodynamic, Garching (Germany); Zell, Martin [ESA-ESTEC, Directorate of Human Spaceflight, Head of ISS Utilisation Department, Noordwijk (Netherlands)

    2010-11-15

    In literature it is generally supposed that under terrestrial conditions the driving force in natural, nucleate boiling heat transfer is namely buoyancy caused by earth gravity, which is expressed in the empirical correlations for technical applications. However, experiments in microgravity performed during the past three decades demonstrate unanimously that up to a medium level heat flux the overall heat transfer in pool boiling is nearly independent from gravity. We refer and discuss in this paper on results of experiments performed with various liquids and liquid states and also using various heater geometries on mission platforms which provide low gravity for short and long periods. Beside the measurements of the experimental parameters to determine the heat transfer, we observed the macroscopic boiling process itself with movie films and videos in order to study the bubble dynamics. From these records we learned about the mechanisms of heat and vapour bubble transport, about the interaction between solid heater, superheated liquid, and vapour without gravity or other external force only generated by the bubbles themselves, and we observed significant details about the boiling process not recognized so far. These findings are essential for a better understanding of the complex physical process; and therefore they are important for the formulation of empirical correlations, and in future for numerical simulations to predict properly boiling heat transfer for technical applications. (orig.)

  20. Heat-transport mechanisms in molecular building blocks of inorganic/organic hybrid superlattices

    Science.gov (United States)

    Giri, Ashutosh; Niemelä, Janne-Petteri; Tynell, Tommi; Gaskins, John T.; Donovan, Brian F.; Karppinen, Maarit; Hopkins, Patrick E.

    2016-03-01

    Nanomaterial interfaces and concomitant thermal resistances are generally considered as atomic-scale planes that scatter the fundamental energy carriers. Given that the nanoscale structural and chemical properties of solid interfaces can strongly influence this thermal boundary conductance, the ballistic and diffusive nature of phonon transport along with the corresponding phonon wavelengths can affect how energy is scattered and transmitted across an interfacial region between two materials. In hybrid composites composed of atomic layer building blocks of inorganic and organic constituents, the varying interaction between the phononic spectrum in the inorganic crystals and vibronic modes in the molecular films can provide a new avenue to manipulate the energy exchange between the fundamental vibrational energy carriers across interfaces. Here, we systematically study the heat transfer mechanisms in hybrid superlattices of atomic- and molecular-layer-grown zinc oxide and hydroquinone with varying thicknesses of the inorganic and organic layers in the superlattices. We demonstrate ballistic energy transfer of phonons in the zinc oxide that is limited by scattering at the zinc oxide/hydroquinone interface for superlattices with a single monolayer of hydroquinone separating the thicker inorganic layers. The concomitant thermal boundary conductance across the zinc oxide interfacial region approaches the maximal thermal boundary conductance of a zinc oxide phonon flux, indicative of the contribution of long wavelength vibrations across the aromatic molecular monolayers in transmitting energy across the interface. This transmission of energy across the molecular interface decreases considerably as the thickness of the organic layers are increased.

  1. Threshold switching mechanism by high-field energy gain in the hopping transport of chalcogenide glasses

    Science.gov (United States)

    Ielmini, Daniele

    2008-07-01

    Chalcogenide glasses are widely used in phase-change nonvolatile memories and in optical recording media for their ability to rapidly change their structure to crystalline, thus obtaining different electrical resistance and optical reflectivity. Chalcogenide glasses universally display threshold switching, that is a sudden, reversible transition from a high-resistivity state to a low-resistivity state observed in the current-voltage (I-V) characteristic. Since threshold switching controls the operating voltage and speed of phase-change memories, the predictability of the switching voltage, current, and speed is of critical importance for selecting the proper chalcogenide material for memory applications. Although threshold switching has long been recognized to be an electronic process with an intimate relation to localized states, its detailed physical mechanism is still not clear. In this work, threshold switching is explained by the field-induced energy increase in electrons in their hopping transport, moderated by the energy relaxation due to phonon-electron interaction. The energy increase leads to an enhancement of conductivity and a collapse of the electric field within the amorphous chalcogenide layer, accounting for the observed negative differential resistance at switching. Threshold switching is found to obey to a constant electrical-power condition. The proposed model generally applies to low-mobility semiconductors featuring a deep Fermi level and hopping-type conduction, and can predict the thickness, temperature, and material dependence of threshold voltage and current.

  2. Electric vehicles and renewable energy in the transport sector - energy system consequences. Main focus: Battery electric vehicles and hydrogen based fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, L.H.; Joergensen, K.

    2000-04-01

    The aim of the project is to analyse energy, environmental and economic aspects of integrating electric vehicles in the future Danish energy system. Consequences of large-scale utilisation of electric vehicles are analysed. The aim is furthermore to illustrate the potential synergistic interplay between the utilisation of electric vehicles and large-scale utilisation of fluctuating renewable energy resources, such as wind power. Economic aspects for electric vehicles interacting with a liberalised electricity market are analysed. The project focuses on battery electric vehicles and fuel cell vehicles based on hydrogen. Based on assumptions on the future technical development for battery electric vehicles, fuel cell vehicles on hydrogen, and for the conventional internal combustion engine vehicles, scenarios are set up to reflect expected options for the long-term development of road transport vehicles. Focus is put on the Danish fleet of passenger cars and delivery vans. The scenario analysis includes assumptions on market potential developments and market penetration for the alternative vehicles. Vehicle replacement rates in the Danish transport fleet and the size of fleet development are based on data from The Danish Road Directorate. The electricity supply system development assumed is based on the Danish energy plan, Energy 21, The Plan scenario. The time horizon of the analysis is year 2030. Results from the scenario analysis include the time scales involved for the potential transition towards electricity based vehicles, the fleet composition development, the associated developments in transport fuel consumption and fuel substitution, and the potential CO{sub 2}-emission reduction achievable in the overall transport and power supply system. Detailed model simulations, on an hourly basis, have furthermore been carried out for year 2005 that address potential electricity purchase options for electric vehicles in the context of a liberalised electricity market. The baseline electricity market considered comprises a spot market and a balance market. The structure chosen for the baseline spot market is close to the structure of the Nord Pool electricity market, and the structure of the balance or regulatory market is close to the Norwegian model. (au)

  3. Electric vehicles and renewable energy in the transport sector - energy system consequences. Main focus: Battery electric vehicles and hydrogen based fuel cell vehicles

    International Nuclear Information System (INIS)

    The aim of the project is to analyse energy, environmental and economic aspects of integrating electric vehicles in the future Danish energy system. Consequences of large-scale utilisation of electric vehicles are analysed. The aim is furthermore to illustrate the potential synergistic interplay between the utilisation of electric vehicles and large-scale utilisation of fluctuating renewable energy resources, such as wind power. Economic aspects for electric vehicles interacting with a liberalised electricity market are analysed. The project focuses on battery electric vehicles and fuel cell vehicles based on hydrogen. Based on assumptions on the future technical development for battery electric vehicles, fuel cell vehicles on hydrogen, and for the conventional internal combustion engine vehicles, scenarios are set up to reflect expected options for the long-term development of road transport vehicles. Focus is put on the Danish fleet of passenger cars and delivery vans. The scenario analysis includes assumptions on market potential developments and market penetration for the alternative vehicles. Vehicle replacement rates in the Danish transport fleet and the size of fleet development are based on data from The Danish Road Directorate. The electricity supply system development assumed is based on the Danish energy plan, Energy 21, The Plan scenario. The time horizon of the analysis is year 2030. Results from the scenario analysis include the time scales involved for the potential transition towards electricity based vehicles, the fleet composition development, the associated developments in transport fuel consumption and fuel substitution, and the potential CO2-emission reduction achievable in the overall transport and power supply system. Detailed model simulations, on an hourly basis, have furthermore been carried out for year 2005 that address potential electricity purchase options for electric vehicles in the context of a liberalised electricity market. The baseline electricity market considered comprises a spot market and a balance market. The structure chosen for the baseline spot market is close to the structure of the Nord Pool electricity market, and the structure of the balance or regulatory market is close to the Norwegian model. (au)

  4. Contribution of the organic anion transporter OAT2 to the renal active tubular secretion of creatinine and mechanism for serum creatinine elevations caused by cobicistat

    OpenAIRE

    Lepist, Eve-Irene; Zhang, Xuexiang; Hao, Jia; Huang, Jane; Kosaka, Alan; Birkus, Gabriel; Murray, Bernard P.; Bannister, Roy; Cihlar, Tomas; Huang, Yong; Ray, Adrian S

    2014-01-01

    Many xenobiotics including the pharmacoenhancer cobicistat increase serum creatinine by inhibiting its renal active tubular secretion without affecting the glomerular filtration rate. This study aimed to define the transporters involved in creatinine secretion, applying that knowledge to establish the mechanism for xenobiotic-induced effects. The basolateral uptake transporters organic anion transporter OAT2 and organic cation transporters OCT2 and OCT3 were found to transport creatinine. At ...

  5. The role of lock-in mechanisms in transition processes: The case of energy for road transport

    DEFF Research Database (Denmark)

    Klitkou, Antje; Bolwig, Simon; Hansen, Teis; Wessberg, Nina

    2015-01-01

    This paper revisits the theoretical concepts of lock-in mechanisms to analyse transition processes in energy production and road transportation in the Nordic countries, focussing on three technology platforms: advanced biofuels, e-mobility and hydrogen and fuel cell electrical vehicles. The paper...

  6. Rate and mechanism of facilitated americium(III) transport through a supported liquid membrane containing a bifunctional organophosphorus mobile carrier

    International Nuclear Information System (INIS)

    The facilitated transport of Am(III) from aqueous nitrate solutions to formic acid aqueous solutions through a supported liquid membrane (SLM) is described. The supported liquid membrane consists of a solution of a new (carbamoylmethyl)phosphine oxide in diethylbenzene (DEB) absorbed into a 48 μm thick microporous polypropylene film. The transport mechanism consists of a diffusion process through an aqueous diffusion film, a fast interfacial chemical reaction, and diffusion through the membrane itself. Equations describing the rate of transport are derived. They correlate the membrane permeability coefficient to diffusional parameters and to the chemical composition of the system. Different rate-controlling processes are shown to control the membrane permeability when the composition of the system is varied and as long as the transport occurs. The experimental data are quantitatively explained with the derived equations. The diffusion coefficient of the permeating species and the equilibrium constant of the fast interfacial reactions are evaluated. 13 figures, 1 table

  7. Investigating radionuclide bearing suspended sediment transport mechanisms in the Ribble estuary using airborne remote sensing

    International Nuclear Information System (INIS)

    BNFL Sellafield has been authorised to discharge radionuclides to the Irish Sea since 1952. In the aquatic environment the radionuclides are adsorbed by sediments and are thus redistributed by sediment transport mechanisms. This sediment is known to accumulate in the estuaries of the Irish Sea. BNFL Springfields is also licensed to discharge isotopically different radionuclides directly to the Ribble estuary. Thus there is a need to understand the sediment dynamics of the Ribble estuary in order to understand the fate of these radionuclides within the Ribble estuary. Estuaries are highly dynamic environments that are difficult to monitor using the conventional sampling techniques. However, remote sensing provides a potentially powerful tool for monitoring the hydrodynamics of the estuarine environment by providing data that are both spatially and temporally representative. This research develops a methodology for mapping suspended sediment concentration (SSC) in the Ribble estuary using airborne remote sensing. The first hypothesis, that there is a relationship between SSC and 137Cs concentration is proven in-situ (R2=0.94), thus remotely sensed SSC can act as a surrogate for 137Cs concentration. Initial in-situ characterisation of the suspended sediments was investigated to identify spatial and temporal variability in grain size distributions and reflectance characteristics for the Ribble estuary. Laboratory experiments were then performed to clearly define the SSC reflectance relationship, identify the optimum CASI wavelengths for quantifying SSC and to demonstrate the effects on reflectance of the environmental variables of salinity and clay content. Images were corrected for variation in solar elevation and angle to give a ground truth calibration for SSC, with an R2=0.76. The remaining scatter in this relationship was attributed to the differences in spatial and temporal representation between sampling techniques and remote sensing. The second hypothesis assumes that a series of images over a flood tide can be animated to provide information on the hydrodynamic regime, erosion, and deposition. Spatial and temporal data demonstrated the complex controls on sediment transport. The data also showed the importance of microphytobenthos in the stabilisation of intertidal sediments, highlighting their importance in defining sources and sinks of radionuclides in intertidal areas. Water volume data from the VERSE model were combined with SSC from the imagery to calculate the total sediment in suspension for each flight line. This provided the figures used to determine total erosion and deposition, which were then used to derive net suspended sediment and 137Cs influxes of 2.01x106 kg and 604MBq per flood tide. (author)

  8. Transport

    International Nuclear Information System (INIS)

    Here are given the European Union Commission directives (2001/6 and 2001/7) of the 29. of January 2001 relative to the Member States legislation rapprochement and concerning the transport of dangerous goods by rail (2001/6) and road (2001/7). The directives 96/49 and 94/55 are therefore modified; Member States have to transpose them before the 31. of December 2001 for class 7 goods (radioactive materials) and before the 31. of December 2002 for the other classes. (O.M.)

  9. Electrical transport and EPR investigations: A comparative study for d.c. conduction mechanism in monovalent and multivalent ions doped polyaniline

    Indian Academy of Sciences (India)

    Suresh Kumar Gupta; Vandna Luthra; Ramadhar Singh

    2012-10-01

    A detailed comparative study of electron paramagnetic resonance (EPR) in conjunction with d.c. electrical conductivity has been undertaken to know about the charge transport mechanism in polyaniline (PANI) doped with monovalent and multivalent protonic acids. This work is in continuation of our previous work for further understanding the conduction mechanism in conducting polymers. The results reveal that the polarons and bipolarons are the main charge carriers formed during doping process and these cause increase in electrical conductivity not only by increase in their concentration but also because of their enhanced mobility due to increased inter-chain transport in polyaniline at high doping levels. EPR line asymmetry having Dysonian line shape for highly doped samples shows a marked deviation of amplitudes / ratio from values close to one to much high values as usually observed in metals, thereby support the idea of high conductivity at higher doping levels. The nature of dopant ions and their doping levels control the charge carriers concentration as well as electrical conductivity of polyaniline. The electrical conductivity has also been studied as a function of temperature to know the thermally assisted transport process of these charge carriers at different doping levels which has been found to follow the Mott’s variable range hopping (VRH) conduction model for all the three dopants used. The charge carriers show a change over from 3D VRH to quasi 1D VRH hopping process for multivalent ions at higher doping levels whereas 1D VRH has been followed by monovalent ion for full doping range. These studies collectively give evidence of inter-chain percolation at higher doping levels causing increase in effective mobility of the charge carriers which mainly seems to govern the electrical conduction behaviour in this system.

  10. Current-transport mechanism in Au/V-doped PVC+TCNQ/p-Si structures

    Science.gov (United States)

    Tecimer, H.; Vural, Ö.; Kaya, A.; Altındal, Ş.

    2015-03-01

    The forward and reverse bias current-voltage (I-V) characteristics of Au/V-doped polyvinyl chloride+Tetracyanoquino dimethane/porous silicon (PVC+TCNQ/p-Si) structures have been investigated in the temperature range of 160-340 K. The zero bias or apparent barrier height (BH) (Φap = ΦBo) and ideality factor (nap = n) were found strongly temperature dependent and the value of nap decreases, while the Φap increases with the increasing temperature. Also, the Φap versus T plot shows almost a straight line which has positive temperature coefficient and it is not in agreement with the negative temperature coefficient of ideal diode or forbidden bandgap of Si (αSi = -4.73×10-4eV/K). The high value of n cannot be explained only with respect to interfacial insulator layer and interface traps. In order to explain such behavior of Φap and nap with temperature, Φap Versus q/2kT plot was drawn and the mean value of (ΦBo) and standard deviation (σs) values found from the slope and intercept of this plot as 1.176 eV and 0.152 V, respectively. Thus, the modified (ln(Io/T2)-(qσs)2/2(kT)2 versus (q/kT) plot gives the ΦBo and effective Richardson constant A* as 1.115 eV and 31.94 Aṡ(cmṡK)-2, respectively. This value of A*( = 31.94 Aṡ(cmṡK)-2) is very close to the theoretical value of 32 Aṡ(cmṡK)-2 for p-Si. Therefore, the forward bias I-V-T characteristics confirmed that the current-transport mechanism (CTM) in Au/V-doped PVC+TCNQ/p-Si structures can be successfully explained in terms of the thermionic emission (TE) mechanism with a Gaussian distribution (GD) of BHs at around mean BH.

  11. Mechanical, sorption and transport experiments on a German high volatile bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Gensterblum, Y.; Krooss, B.M. [RWTH Aachen Univ. (Germany). Inst. of Geology and Geochemistry of Petroleum and Coal; Massarotto, Paul [Queensland Univ., Brisbane, St Lucia, QLD (Australia). School of Engineering

    2013-08-01

    A high volatile bituminous coal (vitrinite reflectance: 0.93%, carbon content: 83%) from the Prosper-Haniel mine, North Rhine-Westphalia has been studied using a comprehensive set of measurements and experimental procedures at RWTH Aachen University and the University of Queensland. Using the True Triaxial Stress Coal Permeameter (TTSCP) (Massarotto 2003) of the University of Queensland, permeability and gas displacement tests were performed on an 80 mm cube of the Prosper-Haniel coal. Extensive data sets were recorded to assess the effects of stress changes on gas transport and the impact of nitrogen, methane and CO{sub 2} sorption on the mechanical properties. We investigate the permeability coefficients for helium, nitrogen, methane and carbon dioxide measured on this sample as a function of net stress. As expected, permeability values decrease with increasing stress. Methane and nitrogen have nearly identical permeability coefficients throughout the entire net stress range, while permeability coefficients measured with helium are higher and those measured with CO{sub 2} significantly lower. During the permeability measurements with CO{sub 2} an anisotropic swelling of the coal cube by about 0.19% to 0.23% was observed. The volumetric effect (swelling) is 100 times slower than gas displacement. Simultaneous mechanical tests indicated a softening of the coal block upon exposure to CO{sub 2}. Thus, a decrease of Young's modulus (YM) of the coal cube during the CO{sub 2} flow test was observed as compared to the methane and nitrogen tests. High-pressure sorption isotherms with CH{sub 4} and CO{sub 2} were determined on different grain-size fractions of the Prosper-Haniel coal at 318K and different moisture contents. Methane sorption capacity decreases by 29% with increasing moisture content. Also, a decrease of sorption rate was observed with increasing moisture content. While sorption rates are generally faster for CO{sub 2} than for CH{sub 4}, the sorption rates of CH{sub 4} and CO{sub 2} at a moisture content of 1.6 % were nearly identical. The results of this study are compared with those of similar experiments performed on a other sets of coals (Busch and Gensterblum, 2011). Finally several theoretical models to predict the reservoir permeability as a function of reservoir pressure has been tested. (orig.)

  12. Two-Dimensional Hopping Conductivity: Experimental Evidence for a Novel Electron Transport Mechanism

    International Nuclear Information System (INIS)

    Results are presented of measurements of two-dimensional (2D) variable-range-hopping (VRH) conductivity and magnetoresistance (MR) in a delta-doped GaAs/AlGaAs heterostructure. It is shown that at zero magnetic field and low temperatures (T xx(T) exhibits 'Coulomb-gap behavior': ρ(T) =: ρ0exp(T0/T)1/2 with the pre factor ρ0 = (h/e2) which is independent of temperature and electron density. This value of po exactly coincides with that observed by Mason et al. in a different material - Si-MOSFET. Universality of the hopping pre factor is considered as evidence that in some interval of electron densities close to the metal-insulator transition, the 2D VRH is assisted by the electron-electron interaction (EEI), rather than by conventional electron-phonon interaction. Experimental data show that (i) existence of a delta-doped layer in the proximate vicinity of the 2D conducting plane favors EEI-assisted VRH, and (ii) a strong magnetic field parallel to the 2D plane leads to the suppression of the EEI-assistance and the restoration of the conventional phonon-assisted hopping. To interpret these experimental observations, a novel electron transport mechanism is suggested, according to which the current-carrying single electron move via quantum resonant tunneling between localized states, brought into resonance by fast electron hops in their environment. The last hops can be assisted by phonons; however, the phonon frequency does not appear in the final expression for the current-carrying transition rate

  13. Paddle-wheel versus percolation mechanism for cation transport in some sulphate phases

    DEFF Research Database (Denmark)

    Andersen, N.H.; Bandaranyake, P.W.S.K.; Careem, M.A.; Dissanayake, M.A.K.L.; Wijayasekera, C.N.; Kaber, R.; Lundén, A.; Mellander, B.-E.; Nilsson, L.; Thomas, J.O.

    transported along a slightly curved pathway of continuous lithium occupation corresponding to a distance of about 3.7 angstrom. Thus, lithium transport occurs in one of the six directions [110], [110BAR], [101] etc. The electrical conductivity has been studied for solid solutions of lithium tungstate in cubic...

  14. Structure and molecular mechanism of a nucleobase-cation-symport-1 family transporter

    DEFF Research Database (Denmark)

    Weyand, Simone; Shimamura, Tatsuro; Yajima, Shunsuke; Suzuki, Shun'ichi; Mirza, Osman Asghar; Krusong, Kuakarun; Carpenter, Elisabeth P; Rutherford, Nicholas G; Hadden, Jonathan M; O'Reilly, John; Ma, Pikyee; Saidijam, Massoud; Patching, Simon G; Hope, Ryan J; Norbertczak, Halina T; Roach, Peter C J; Iwata, So; Henderson, Peter J F; Cameron, Alexander D

    2008-01-01

    The nucleobase-cation-symport-1 (NCS1) transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85-angstrom resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 trans...

  15. Elucidation of Transport Mechanism of Paeoniflorin and the Influence of Ligustilide, Senkyunolide I and Senkyunolide A on Paeoniflorin Transport through Mdck-Mdr1 Cells as Blood–Brain Barrier in Vitro Model

    OpenAIRE

    Peng-Yi Hu; Dan Liu; Qin Zheng; Qing Wu; Yu Tang; Ming Yang

    2016-01-01

    The objectives of the present investigation were to: (1) elucidate the transport mechanism of paeoniflorin (PF) across MDCK-MDR1 monolayers; and (2) evaluate the effect of ligustilide (LIG), senkyunolide I (SENI) and senkyunolide A (SENA) on the transport of PF through blood–brain barrier so as to explore the enhancement mechanism. Transport studies of PF were performed in both directions, from apical to basolateral side (A→B) and from basolateral to apical sides (B→A). Drug concentrations we...

  16. Mechanisms for Two-Step Proton Transfer Reactions in the Outward-Facing Form of MATE Transporter.

    Science.gov (United States)

    Nishima, Wataru; Mizukami, Wataru; Tanaka, Yoshiki; Ishitani, Ryuichiro; Nureki, Osamu; Sugita, Yuji

    2016-03-29

    Bacterial pathogens or cancer cells can acquire multidrug resistance, which causes serious clinical problems. In cells with multidrug resistance, various drugs or antibiotics are extruded across the cell membrane by multidrug transporters. The multidrug and toxic compound extrusion (MATE) transporter is one of the five families of multidrug transporters. MATE from Pyrococcus furiosus uses H(+) to transport a substrate from the cytoplasm to the outside of a cell. Crystal structures of MATE from P. furiosus provide essential information on the relevant H(+)-binding sites (D41 and D184). Hybrid quantum mechanical/molecular mechanical simulations and continuum electrostatic calculations on the crystal structures predict that D41 is protonated in one structure (Straight) and, both D41 and D184 protonated in another (Bent). All-atom molecular dynamics simulations suggest a dynamic equilibrium between the protonation states of the two aspartic acids and that the protonation state affects hydration in the substrate binding cavity and lipid intrusion in the cleft between the N- and C-lobes. This hypothesis is examined in more detail by quantum mechanical/molecular mechanical calculations on snapshots taken from the molecular dynamics trajectories. We find the possibility of two proton transfer (PT) reactions in Straight: the 1st PT takes place between side-chains D41 and D184 through a transient formation of low-barrier hydrogen bonds and the 2nd through another H(+) from the headgroup of a lipid that intrudes into the cleft resulting in a doubly protonated (both D41 and D184) state. The 1st PT affects the local hydrogen bond network and hydration in the N-lobe cavity, which would impinge on the substrate-binding affinity. The 2nd PT would drive the conformational change from Straight to Bent. This model may be applicable to several prokaryotic H(+)-coupled MATE multidrug transporters with the relevant aspartic acids. PMID:27028644

  17. Comparison of mechanical and manual ventilation during transport of patients to the intensive care unit after cardiac surgery

    Directory of Open Access Journals (Sweden)

    Atilla Canbulat

    2012-12-01

    Full Text Available Objectives: We compared effects of mechanical andmanual ventilation during transport to the intensive careunit(ICU in cardiac surgeries.Materials and methods: After ethical approval, 66 patients(ASAgrade II and III, 20-80years were assignedrandomly. Ventilation during transport to ICU was performedmanual (Group EV; n=36 or mechanical ventilation(Group MV; n=30. Measurements were recorded:operation room (A, during transport (T and in ICU (YB.Systolic, diastolic pressures (SAP, DAP, pulmonary arterialpressure (PAP, pulmonary capillary wedge pressure(PCWP, central venous pressure (CVP, heart rate (HR,cardiac output (CO, blood gases (pH, PCO2, PO2, BEand peripheral oxygen saturation (SpO2 were recorded.Stroke volume index (SVI, systemic and pulmonary vascularresistance indices (SVRI, PVRI and mean arterialpressures(MAP were calculated.Results: Patients were similar. Duration of transportwas shorter in Group MV (p< 0.01. The alterations inHR, MAP, DAP, CVP, PAP, PCWP, PVRI, SVRI, SVI, CO,SpO2 were similar, the increase in SAP during T periodwas higher in Group MV (p<0.05. Pulmonary arterial pHin Group MV was lower (p< 0.05. Arterial and pulmonaryarterial pO2, pCO2 decreased in Group MV, there was increasein Group EV during ICU (p< 0.001, p< 0.01, p<0.01, p< 0.05. During T period hypotension and tachycardiain Group EV, and hypertension in Group MV wereobserved.Conclusions: Mechanical ventilation had short transporttime, less alterations in hemodynamic and respiration valuesand less complication rates. We concluded that theuse of mechanical ventilation is a safer method for theintrahospital transport of critical patients. J Clin Exp Invest2012; 3(4: 521-528Key words: Cardiac surgery, patient transport, mechanicalventilator, manual ventilator, hemodynamia

  18. A multi-scale approach of mechanical and transport properties of cementitious materials under rises of temperature

    International Nuclear Information System (INIS)

    The modern industrial activities (storage of nuclear waste, geothermal wells, nuclear power plants,...) can submit cementitious materials to some extreme conditions, for example at temperatures above 200 C. This level of temperature will induce phenomena of dehydration in the cement paste, particularly impacting the CSH hydrates which led to the mechanical cohesion. The effects of these temperatures on the mechanical and transport properties have been the subject of this thesis.To understand these effects, we need to take into account the heterogeneous, porous, multi-scale aspects of these materials. To do this, micro-mechanics and homogenization tools based on the Eshelby problem's solution were used. Moreover, to support this multi-scale modeling, mechanical testing based on the theory of porous media were conducted. The measurements of modulus compressibility, permeability and porosity under confining pressure were used to investigate the mechanisms of degradation of these materials during thermal loads up to 400 C. (author)

  19. Human Equilibrative Nucleoside Transporter-1 Knockdown Tunes Cellular Mechanics through Epithelial-Mesenchymal Transition in Pancreatic Cancer Cells

    OpenAIRE

    Lee, Yeonju; Koay, Eugene J.; Zhang, Weijia; Qin, Lidong; Kirui, Dickson K.; Hussain, Fazle; Shen, Haifa; Ferrari, Mauro

    2014-01-01

    We report cell mechanical changes in response to alteration of expression of the human equilibrative nucleoside transporter-1 (hENT1), a most abundant and widely distributed plasma membrane nucleoside transporter in human cells and/or tissues. Modulation of hENT1 expression level altered the stiffness of pancreatic cancer Capan-1 and Panc 03.27 cells, which was analyzed by atomic force microscopy (AFM) and correlated to microfluidic platform. The hENT1 knockdown induced reduction of cellular ...

  20. A Study of e- Transport through Li2O2, the Main Discharge Product in the Li-O2 Battery

    DEFF Research Database (Denmark)

    Knudsen, Kristian Bastholm; Jensen, Søren Højgaard; Luntz, Alan C.; Hjelm, Johan

    solvents etc. [2] [3]. In order to improve the electrochemical performance of the Li-O2batteries; it is crucial to understand the fundamental mechanisms that governs and limits the system during electrochemical operation. Here we present a redox probing study of the charge transfer across the deposition...... Polaron Charge Transport through Li2O2 in Li-O2 Batteries," J. Phys. Chem. Lett., vol. 4, pp. 3494-3499, 2013....

  1. Description of the transport mechanisms and pathways in the far field of a KBS-3 type repository

    International Nuclear Information System (INIS)

    The main purpose of this document is to serve as a reference document for the far field radionuclide transport description within SKB 91. A conceptual description of far field transport in crystalline rock is given together with a discussion of the application of the stream tube concept. In this concept the transport in a complex tree-dimensional flow field is divided into a number of imaginary tubes which are modelled independently. The stream tube concept is used as the basis for the radionuclide calculations in SKB 91. Different mathematical models for calculating the transport of radionuclides in fractured rock are compared: advection dispersion models, channeling models and network models. In the SKB 91 project a dual-porosity continuum model based on the one dimensional advection-dispersion equation taking into account matrix diffusion, sorption in the rock matrix and radioactive chain decay. Furthermore, the data needed for the transport models is discussed and recommended ranges and central values are given. (42 refs.) (au)

  2. Mechanisms affecting the transport and retention of bacteria, bacteriophage and microspheres in laboratory-scale saturated fractures

    Science.gov (United States)

    Seggewiss, G.; Dickson, S. E.

    2013-12-01

    Groundwater is becoming an increasingly important water source due to the ever-increasing demands from agricultural, residential and industrial consumers. In search of more secure sources, wells are routinely finished over large vertical depths in bedrock aquifers, creating new hydraulic pathways and thus increasing the risk of cross contamination. Moreover, hydraulic pathways are also being altered and created by increasing water withdrawal rates from these wells. Currently, it is not well understood how biological contaminants are transported through, and retained in, fractured media thereby making risk assessment and land use decisions difficult. Colloid transport within fractured rock is a complex process with several mechanisms affecting transport and retention, including: advection, hydrodynamic dispersion, diffusion, size exclusion, adsorption, and decay. Several researchers have investigated the transport of bacteria, bacteriophage, and microspheres (both carboxylated and plain) to evaluate the effects of surface properties and size on transport and retention. These studies have suggested that transport is highly dependent on the physico-chemical properties of the particle, the fracture, and the carrying fluid. However, these studies contain little detail regarding the specific mechanisms responsible for transport beyond speculating about their existence. Further, little work has been done to compare the transport of these particulate materials through the same fracture, allowing for direct observations based on particulate size and surface properties. This research examines the similarities and differences in transport and retention between four different particles through two different laboratory-scale, saturated fractures. This work is designed to explore the effects of particle size, surface properties, ionic strength of the carrying solution, and aperture field characteristics on transport and retention in single, saturated fractures. The particulates chosen for this work include E.coli RS2-GFP, MS2, and carboxylated microspheres with diameters of 0.0425 μm and 0.525 μm. The results of this work will contribute to the understanding of risk posed by contaminants to bedrock aquifer sources. Dolomite rock samples were collected from the DoLime quarry in Guelph, Ontario. A single fracture was induced in the sample by applying a uniaxial force. Lengthwise edges were sealed to create no-flow boundaries, and flow cells were fitted on the up- and down-stream ends of the fracture. Aperture size and variability were characterized using hydraulic and solute tracer tests. Particulate tracer tests were conducted by injecting a pulse of particles (E.coli RS2-GFP, MS2, or microspheres) into the upstream flow cell, and measuring the subsequent effluent concentration profile. From these tests, the percent recovery and mean residence time of the particulate were analyzed. Generally, it was found that microspheres are a poor indication of biological particulate transport, likely due to differences in surface properties affecting the retention mechanisms. This talk will provide an analysis of the breakthrough curves, with specific details regarding the transport and retention mechanisms for the various types and sizes of particles employed in these experiments.

  3. Deposition patterns and transport mechanisms for the endocrine disruptor 4-nonylphenol across the Sierra Nevada Mountains, California.

    Science.gov (United States)

    Lyons, Rebecca; Van de Bittner, Kyle; Morgan-Jones, Sean

    2014-12-01

    Dust and particulate distribution patterns are shifting as global climate change brings about longer drought periods. Particulates act as vehicles for long range transport of organic pollutants, depositing at locations far from their source. Nonylphenol, a biodegradation product of nonylphenol polyethoxylate, is a known endocrine disruptor. Nonylphenol polyethoxylate enters the environment as an inert ingredient in pesticide sprays, potentially traveling great distances from its application site. This is of concern when a highly agricultural region, California's Central Valley, lies adjacent to sensitive areas like the Eastern Sierra Nevada Mountains. The distribution and transport mechanisms for 4-nonylphenol were investigated in Eastern Sierra Nevada canyons. Regions close to canyon headwalls showed trace amounts of 4-nonylphenol in surface water, snow, and atmospheric deposition. Exposed areas had yearly average concentrations as high as 9?g/L. Distribution patterns are consistent with particulate-bound transport. This suggests with increasing drought periods, higher levels of persistent organic pollutants are likely. PMID:25215456

  4. ABC transporters as multidrug resistance mechanisms and the development of chemosensitizers for their reversal

    Directory of Open Access Journals (Sweden)

    Choi Cheol-Hee

    2005-10-01

    Full Text Available Abstract One of the major problems related with anticancer chemotherapy is resistance against anticancer drugs. The ATP-binding cassette (ABC transporters are a family of transporter proteins that are responsible for drug resistance and a low bioavailability of drugs by pumping a variety of drugs out cells at the expense of ATP hydrolysis. One strategy for reversal of the resistance of tumor cells expressing ABC transporters is combined use of anticancer drugs with chemosensitizers. In this review, the physiological functions and structures of ABC transporters, and the development of chemosensitizers are described focusing on well-known proteins including P-glycoprotein, multidrug resistance associated protein, and breast cancer resistance protein.

  5. Mechanism of active transport: Free energy dissipation and free energy transduction

    OpenAIRE

    Tanford, C

    1983-01-01

    The thermodynamic pathway for "chemiosmotic" free energy transduction in active transport is discussed with an ATP-driven Ca2+ pump as an illustrative example. Two innovations are made in the analysis. (i) Free energy dissipated as heat is rigorously excluded from overall free energy bookkeeping by focusing on the dynamic equilibrium state of the chemiosmotic process. (ii) Separate chemical potential terms for free energy donor and transported ions are used to keep track of the thermodynamic ...

  6. Mechanisms of equinatoxin II-induced transport through the membrane of a giant phospholipid vesicle.

    OpenAIRE

    Mally, M; Majhenc, J; Svetina, S; Zeks, B.

    2002-01-01

    Protein equinatoxin II from sea anemone Actinia equina L. was used to form pores in phospholipid membranes. We studied the effect of these pores on the net transmembrane transport of sucrose and glucose by observing single giant (cell-size) vesicles under the phase contrast microscope. Sugar composition in the vesicle was determined by measuring the width of the halo, which appears around the vesicle in the phase contrast image. The transport of sugars was induced when a vesicle, filled with ...

  7. Transport and Removal Mechanisms of Trace Organic Pollutants by Nanofiltration and Reverse Osmosis Membranes

    OpenAIRE

    Wang, Jinwen

    2014-01-01

    The objective and focus of this study is to fully understand trace organic pollutant transport through NF/RO membranes. An extension of the classical solution-diffusion model had been developed that relates transport through NF/RO membranes directly to membrane structure descriptors (i.e., effective barrier layer pore size, porosity and thickness, etc.). In general, model predictions agreed well with experimental data suggesting the model captures the phenomenological behavior of commercial N...

  8. Acrylamide Retards the Slow Axonal Transport of Neurofilaments in Rat Cultured Dorsal Root Ganglia Neurons and the Corresponding Mechanisms.

    Science.gov (United States)

    An, Lihong; Li, Guozhen; Si, Jiliang; Zhang, Cuili; Han, Xiaoying; Wang, Shuo; Jiang, Lulu; Xie, Keqin

    2016-05-01

    Chronic acrylamide (ACR) exposure induces peripheral-central axonopathy in occupational workers and laboratory animals, but the underlying mechanisms remain unclear. In this study, we first investigated the effects of ACR on slow axonal transport of neurofilaments in cultured rat dorsal root ganglia (DRG) neurons through live-cell imaging approach. Then for the underlying mechanisms exploration, the protein level of neurofilament subunits, motor proteins kinesin and dynein, and dynamitin subunit of dynactin in DRG neurons were assessed by western blotting and the concentrations of ATP was detected using ATP Assay Kit. The results showed that ACR treatment results in a dose-dependent decrease of slow axonal transport of neurofilaments. Furthermore, ACR intoxication significantly increases the protein levels of the three neurofilament subunits (NF-L, NF-M, NF-H), kinesin, dynein, and dynamitin subunit of dynactin in DRG neurons. In addition, ATP level decreased significantly in ACR-treated DRG neurons. Our findings indicate that ACR exposure retards slow axonal transport of NF-M, and suggest that the increase of neurofilament cargoes, motor proteins, dynamitin of dynactin, and the inadequate ATP supply contribute to the ACR-induced retardation of slow axonal transport. PMID:26721510

  9. Theoretical study and design of a low-grade heat-driven pilot ejector refrigeration machine operating with butane and isobutane and intended for cooling of gas transported in a gas-main pipeline

    KAUST Repository

    Petrenko, V.O.

    2011-11-01

    This paper describes the construction and performance of a novel combined system intended for natural gas transportation and power production, and for cooling of gas transported in a gas-main pipeline. The proposed system includes a gas turbine compressor, a combined electrogenerating plant and an ejector refrigeration unit operating with a hydrocarbon refrigerant. The combined electrogenerating plant consists of a high-temperature steam-power cycle and a low-temperature hydrocarbon vapor power cycle, which together comprise a binary vapor system. The combined system is designed for the highest possible effectiveness of power generation and could find wide application in gas-transmission systems of gas-main pipelines. Application of the proposed system would enable year-round power generation and provide cooling of natural gas during periods of high ambient temperature operation. This paper presents the main results of a theoretical study and design performance specifications of a low-grade heat-driven pilot ejector refrigeration machine operating with butane and isobutane. © 2010 Elsevier Ltd and IIR. All rights reserved.

  10. Triboelectric-Potential-Regulated Charge Transport Through p-n Junctions for Area-Scalable Conversion of Mechanical Energy.

    Science.gov (United States)

    Meng, Xian Song; Wang, Zhong Lin; Zhu, Guang

    2016-01-01

    Regulation of charge-transport direction is realized through the coupling of triboelectrification, electrostatic induction, and semiconducting properties for area-scalable conversion of mechanical energy. The output current from each unit triboelectric generator can always constructively add up due to the unidirectional flow of electrons. This work proposes a practical and general route to area-scalable applications of the triboelectric generator and other energy-harvesting techniques. PMID:26611707

  11. Influence of supplementary cementitious materials on water transport kinetics and mechanical properties of hydrated lime and cement mortars

    OpenAIRE

    Ince, C.; Derogar, S.; Michelitsch, T. M.

    2015-01-01

    The purpose of this paper is an investigation of the possible role of supplementary cementitious materials (SCMs) on water transport kinetics and mechanical properties of hydrated lime (CL90) and Portland cement (PC) mortars. The properties of hydrated lime are significantly different from those of cement and therefore modifying fresh and hardened properties of these mortars are vital for mortar/substrate optimisation in masonry construction. The parameters investigated in this paper often ar...

  12. Multi-Drug Resistance Transporters and a Mechanism-Based Strategy for Assessing Risks of Pesticide Combinations to Honey Bees

    OpenAIRE

    Guseman, Alex J.; Miller, Kaliah; Kunkle, Grace; Dively, Galen P.; Pettis, Jeffrey S.; Evans, Jay D.; vanEngelsdorp, Dennis; Hawthorne, David J.

    2016-01-01

    Annual losses of honey bee colonies remain high and pesticide exposure is one possible cause. Dangerous combinations of pesticides, plant-produced compounds and antibiotics added to hives may cause or contribute to losses, but it is very difficult to test the many combinations of those compounds that bees encounter. We propose a mechanism-based strategy for simplifying the assessment of combinations of compounds, focusing here on compounds that interact with xenobiotic handling ABC transporte...

  13. Estimates of Cl atom concentrations and hydrocarbon kinetic reactivity in surface air at Appledore Island, Maine (USA), during International Consortium for Atmospheric Research on Transport and Transformation/Chemistry of Halogens at the Isles of Shoals

    Science.gov (United States)

    Pszenny, Alexander A. P.; Fischer, Emily V.; Russo, Rachel S.; Sive, Barkley C.; Varner, Ruth K.

    2007-05-01

    Average hydroxyl radical (OH) to chlorine atom (Cl) ratios ranging from 45 to 119 were determined from variability-lifetime relationships for selected nonmethane hydrocarbons (NMHC) in surface air from six different transport sectors arriving at Appledore Island, Maine, during July 2004. Multiplying these ratios by an assumed average OH concentration of 2.5 106 cm-3 yielded estimates of Cl concentrations of 2.2 to 5.6 104 cm-3. Summed reaction rates of methane and more than 30 abundant NMHCs with OH and Cl suggest that Cl reactions increased the kinetic reactivity of hydrocarbons by 16% to 30% over that due to OH alone in air associated with the various transport sectors. Isoprene and other abundant biogenic alkenes were the most important hydrocarbon contributors after methane to overall kinetic reactivity.

  14. Multi-scales modeling of reactive transport mechanisms. Impact on petrophysical properties during CO2 storage

    International Nuclear Information System (INIS)

    The geo-sequestration of carbon dioxide (CO2) is an attractive option to reduce the emission of greenhouse gases. Within carbonate reservoirs, acidification of brine in place can occur during CO2 injection. This acidification leads to mineral dissolution which can modify the transport properties of a solute in porous media. The aim of this study is to quantify the impact of reactive transport on a solute distribution and on the structural modification induced by the reaction from the pore to the reservoir scale. This study is focused on reactive transport problem in the case of single phase flow in the limit of long time. To do so, we used a multi-scale up-scaling method that takes into account (i) the local scale, where flow, reaction and transport are known; (ii) the pore scale, where the reactive transport is addressed by using averaged formulation of the local equations; (iii) the Darcy scale (also called core scale), where the structure of the rock is taken into account by using a three-dimensions network of pore-bodies connected by pore-throats; and (iv) the reservoir scale, where physical phenomenon, within each cell of the reservoir model, are taken into account by introducing macroscopic coefficients deduced from the study of these phenomenon at the Darcy scale, such as the permeability, the apparent reaction rate, the solute apparent velocity and dispersion. (author)

  15. ACIDIFICATION TRENDS AND THE EVOLUTION OF NEUTRALIZATION MECHANISMS THROUGH TIME AT THE BEAR BROOK WATERSHED IN MAINE (BBWM), U.S.A.

    Science.gov (United States)

    The paired catchment study at the forested Bear Brook Watershed in Maine (BBWM) U.S.A. documents interactions among short- to long-term processes of acidification. In 1987-1989, runoff from the two catchments was nearly identical in quality and quantity. Ammonium sulfate has been...

  16. Interfacial Reduction-Oxidation Mechanisms Governing Fate and Transport of Contaminants in the Vadose Zone

    Energy Technology Data Exchange (ETDEWEB)

    Principal Investigator: Baolin Deng, University of Missouri, Columbia, MO; Co-Principal Investigator: Silvia Sabine Jurisson, University of Missouri, Columbia, MO; Co-Principal Investigator: Edward C. Thornton, Pacific Northwest National Laboratory Richland, WA; Co-Principal Investigator: Jeff Terry, Illinois Institute of Technology, Chicago, IL

    2008-05-12

    There are many soil contamination sites at the Department of Energy (DOE) installations that contain radionuclides and toxic metals such as uranium (U), technetium (Tc), and chromium (Cr). Since these contaminants are the main 'risk drivers' at the Hanford site (WA) and some of them also pose significant risk at other DOE facilities (e.g., Oak Ridge Reservation - TN; Rocky Flats - CO), development of technologies for cost effective site remediation is needed. Current assessment indicates that complete removal of these contaminants for ex-situ disposal is infeasible, thus in-situ stabilization through reduction to insoluble species is considered one of the most important approaches for site remediation. In Situ Gaseous Reduction (ISGR) is a technology developed by Pacific Northwest National Laboratory (PNNL) for vadose zone soil remediation. The ISGR approach uses hydrogen sulfide (H{sub 2}S) for reductive immobilization of contaminants that show substantially lower mobility in their reduced forms (e.g., Tc, U, and Cr). The technology can be applied in two ways: (i) to immobilize or stabilize pre-existing contaminants in the vadose zone soils by direct H{sub 2}S treatment, or (ii) to create a permeable reactive barrier (PRB) that prevents the migration of contaminants. Direct treatment involves reduction of the contaminants by H{sub 2}S to less mobile species. Formation of a PRB is accomplished through reduction of ferric iron species in the vadose zone soils by H{sub 2}S to iron sulfides (e.g., FeS), which provides a means for capturing the contaminants entering the treated zone. Potential future releases may occur during tank closure activities. Thus, the placement of a permeable reactive barrier by ISGR treatment can be part of the leak mitigation program. Deployment of these ISGR approaches, however, requires a better understanding of the immobilization kinetics and mechanisms, and a better assessment of the long-term effectiveness of treatment. The primary objective of this project was to understand the complex interactions among the contaminants (i.e., Cr, Tc, and U), H{sub 2}S, and various soil constituents. The reaction with iron sulfide is also the focus of the research, which could be formed from iron oxide reduction by hydrogen sulfide. Factors controlling the reductive immobilization of these contaminants were identified and quantified. The results and fundamental knowledge obtained from this project shall help better evaluate the potential of in situ gaseous treatment to immobilize toxic and radioactive metals examined.

  17. Species transport mechanisms governing capacity loss in vanadium flow batteries: Comparing Nafion® and sulfonated Radel membranes

    International Nuclear Information System (INIS)

    Highlights: • Species transport mechanisms are investigated in Nafion® and s-Radel for VRFBs. • Unlike diffusion in Nafion®, crossover in s-Radel is dominated by convection. • In particular, electro-osmotic convection is the dominant mode in s-Radel. • Change in direction of convection causes a lower crossover in s-Radel. • Hydraulic and electrokinetic permeability are as important as vanadium permeability. -- Abstract: In this study, a 2-D, transient vanadium redox flow battery (VRFB) model was used to investigate and compare the ion transport mechanisms responsible for vanadium crossover in Nafion® 117 and sulfonated Radel (s-Radel) membranes. Specifically, the model was used to distinguish the relative contribution of diffusion, migration, osmotic and electro-osmotic convection to the net vanadium crossover in Nafion® and s-Radel. Model simulations indicate that diffusion is the dominant mode of vanadium transport in Nafion®, whereas convection dominates the vanadium transport through s-Radel due to the lower vanadium permeability, and thus diffusivity of s-Radel. Among the convective transport modes, electro-osmotic convection (i.e., electro-osmotic drag) is found to govern the species crossover in s-Radel due to its higher fixed acid concentration and corresponding free ions in the membrane. Simulations also show that vanadium crossover in s-Radel changes direction during charge and discharge due to the change in the direction of electro-osmotic convection. This reversal in the direction of crossover during charge and discharge is found to result in significantly lower “net” crossover for s-Radel when compared to Nafion®. Comparison of these two membranes also provides guidance for minimizing crossover in VRFB systems and underscores the importance of measuring the hydraulic and the electro-kinetic permeability of a membrane in addition to vanadium diffusion characteristics, when evaluating new membranes for VRFB applications

  18. High-speed transport and magneto-mechanical resonant sensing of superparamagnetic microbeads using magnetic domain walls

    Science.gov (United States)

    Rapoport, Elizabeth

    2013-03-01

    Surface-functionalized superparamagnetic (SPM) microbeads are of great interest in biomedical research and diagnostic device engineering for tagging, manipulating, and detecting chemical and biological species in a fluid environment. Recent work has shown that magnetic domain walls (DWs) can be used to shuttle individual SPM microbeads and magnetically tagged entities across the surface of a chip. This talk will describe the dynamics of SPM microbead transport by nanotrack-guided DWs, and show how these coupled dynamics can be exploited for on-chip digital biosensing applications. Using curvilinear magnetic nanotracks, we demonstrate rapid transport of SPM microbeads at speeds approaching 1000 μm/s, and present a mechanism for selective transport at a junction that allows for the design of complex bead routing networks. We further demonstrate that a SPM bead trapped by a DW exhibits a distinct magneto-mechanical resonance that depends on its hydrodynamic characteristics in the host fluid, and that this resonance can be used for robust size-based discrimination of commercial microbead populations. By embedding a spin-valve sensor within a DW transport conduit, we show that the resonance can be detected electrically and on-the-fly. Thus, we demonstrate a complete set of essential bead handling functions, including capture, transport, identification, and release, required for an integrated lab-on-a-chip platform. In collaboration with Daniel Montana, David Bono, and Geoffrey S.D. Beach, Massachusetts Institute of Technology. This work is supported by the MIT CMSE under NSF-DMR-0819762 and by the MIT Deshpande Center.

  19. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Glenn C.

    1999-12-01

    In this dissertation, results are presented of laboratory investigations and mathematical modeling efforts designed to better understand the interactions of ozone with surfaces. In the laboratory, carpet and duct materials were exposed to ozone and measured ozone uptake kinetics and the ozone induced emissions of volatile organic compounds. To understand the results of the experiments, mathematical methods were developed to describe dynamic indoor aldehyde concentrations, mass transport of reactive species to smooth surfaces, the equivalent reaction probability of whole carpet due to the surface reactivity of fibers and carpet backing, and ozone aging of surfaces. Carpets, separated carpet fibers, and separated carpet backing all tended to release aldehydes when exposed to ozone. Secondary emissions were mostly n-nonanal and several other smaller aldehydes. The pattern of emissions suggested that vegetable oils may be precursors for these oxidized emissions. Several possible precursors and experiments in which linseed and tung oils were tested for their secondary emission potential were discussed. Dynamic emission rates of 2-nonenal from a residential carpet may indicate that intermediate species in the oxidation of conjugated olefins can significantly delay aldehyde emissions and act as reservoir for these compounds. The ozone induced emission rate of 2-nonenal, a very odorous compound, can result in odorous indoor concentrations for several years. Surface ozone reactivity is a key parameter in determining the flux of ozone to a surface, is parameterized by the reaction probability, which is simply the probability that an ozone molecule will be irreversibly consumed when it strikes a surface. In laboratory studies of two residential and two commercial carpets, the ozone reaction probability for carpet fibers, carpet backing and the equivalent reaction probability for whole carpet were determined. Typically reaction probability values for these materials were 10{sup {minus}7}, 10{sup {minus}5}, and 10{sup {minus}5} respectively. To understand how internal surface area influences the equivalent reaction probability of whole carpet, a model of ozone diffusion into and reaction with internal carpet components was developed. This was then used to predict apparent reaction probabilities for carpet. He combines this with a modified model of turbulent mass transfer developed by Liu, et al. to predict deposition rates and indoor ozone concentrations. The model predicts that carpet should have an equivalent reaction probability of about 10{sup {minus}5}, matching laboratory measurements of the reaction probability. For both carpet and duct materials, surfaces become progressively quenched (aging), losing the ability to react or otherwise take up ozone. He evaluated the functional form of aging and find that the reaction probability follows a power function with respect to the cumulative uptake of ozone. To understand ozone aging of surfaces, he developed several mathematical descriptions of aging based on two different mechanisms. The observed functional form of aging is mimicked by a model which describes ozone diffusion with internal reaction in a solid. He shows that the fleecy nature of carpet materials in combination with the model of ozone diffusion below a fiber surface and internal reaction may explain the functional form and the magnitude of power function parameters observed due to ozone interactions with carpet. The ozone induced aldehyde emissions, measured from duct materials, were combined with an indoor air quality model to show that concentrations of aldehydes indoors may approach odorous levels. He shows that ducts are unlikely to be a significant sink for ozone due to the low reaction probability in combination with the short residence time of air in ducts.

  20. Charge transport through DNA/DNA duplexes and DNA/RNA hybrids: complex mechanism study

    Czech Academy of Sciences Publication Activity Database

    Kratochvílová, Irena; Vala, M.; Weiter, M.; Špérová, M.; Schneider, Bohdan; Páv, Ondřej; Šebera, Jakub; Rosenberg, Ivan; Sychrovský, Vladimír

    2013-01-01

    Roč. 20, č. 1 (2013), s. 9-9. ISSN 1211-5894. [Discussions in Structural Molecular Biology. Annual Meeting of the Czech Society for Structural Biology /11./. 14.03.2013-16.03.2013, Nové Hrady] Institutional support: RVO:61388963 ; RVO:68378271 ; RVO:86652036 Keywords : charge transport * fluorescence spectroscopy * DFT Subject RIV: CF - Physical ; Theoretical Chemistry

  1. Mechanism of the Antimicrobial Action of Pyrithione: Effects on Membrane Transport, ATP Levels, and Protein Synthesis

    Science.gov (United States)

    Chandler, Carol J.; Segel, Irwin H.

    1978-01-01

    Pyrithione is a general inhibitor of membrane transport processes in fungi. A brief preincubation of Penicillium mycelia with pyrithione resulted in a marked decrease in the activities of a variety of independently regulated transport systems, including those for inorganic sulfate, inorganic phosphate, methylamine (actually, the NH4+ permease), choline-O-sulfate, glucose, l-methionine (a specific system), and several hydrophobic l-?-amino acids (the general amino acid permease). The degree of inhibition at any fixed pyrithione concentration and exposure time increased as the pH of the incubation medium was decreased. This result strongly suggests that the active species is the un-ionized molecule and that pyrithione acts by collapsing a transmembrane ?pH driving force. The degree of transport inhibition caused by a given concentration of pyrithione increased with increasing time of exposure to the inhibitor. However, exposure time and pyrithione concentration were not reciprocally related. At low pyrithione concentrations, transport inhibition plateaued at some finite value. This observation suggests that the fungi can detoxify low levels of the inhibitor. The concentration of pyrithione required for a given degree of growth inhibition increased as the experimental mycelial density increased. This phenomenon was consistent with the suggestion that the fungi are capable of inactivating pyrithione. PMID:28693

  2. Seat Belt Usage in Injured Car Occupants: Injury Patterns, Severity and Outcome After Two Main Car Accident Mechanisms in Kashan, Iran, 2012

    OpenAIRE

    Mahdi MOHAMMADZADEH; Paravar, Mohammad; MIRZADEH, Azadeh Sadat; Mohammadzadeh, Javad; Mahdian, Soroush

    2015-01-01

    Background: Road traffic accidents (RTAs) are the main public health problems in Iran. The seat belts, which are vehicle safety devices, are imperative to reduce the risk of severe injuries and mortality. Objectives: The aim of the study was to evaluate injury patterns, severity and outcome among belted and unbelted car occupants who were injured in car accidents. Patients and Methods: This cross-sectional prospective study was performed on all car occupants injured in RTAs (n = 822) who were...

  3. An Human Reliability Analysis to Identify Human Error Mechanisms for Reducing the Risks Associated with Human Errors in a Main Control Room of the SMART

    International Nuclear Information System (INIS)

    The research results are summarized as followed: (1) The task analysis performed on the EOGs of the SMART MMIS identified seven different human error mechanisms: Perception Error, Decision Error, Control-Identification Error, Control-Selection Error, Control-Execution Error, Communication Error, and Extraneous Error. The human error mechanisms includes 48 different human error types. 2) The design requirements were proposed to prevent 48 different possible human errors while running the HSI of SMART. 3) Sixteen different human errors were found for the SC designed by KAERI. Fifty six PSFs were also identified influencing the initiation of a human error mechanism. 4) Human factors design requirements were developed to hinder the human error mechanisms. CHED in KHU proposed a design alternative of the SC which took into account the human factors design requirements previously identified. 5) An human error quantification technique was applied to compare the CHED design with that the KAERI's in terms of the probabilities of the human errors caused by each design. The comparison showed that the CHD design was more effective than the KAERI's to reduce the human error probability from 0.0108 to 0.00004. It meant that 96.3% of the human error probability in the KAERI's was prevented by introducing the human factors design recommendations on the SC design

  4. Asymmetric Transport Mechanisms of Hydronium and Hydroxide Ions in Amorphous Solid Water: Hydroxide Goes Brownian while Hydronium Hops.

    Science.gov (United States)

    Lee, Du Hyeong; Choi, Cheol Ho; Choi, Tae Hoon; Sung, Bong June; Kang, Heon

    2014-08-01

    The diffusion of hydronium (H3O(+)) and hydroxide (OH(-)) ions is one of the most intriguing topics in aqueous chemistry. It is considered that these ions in aqueous solutions move via sequential proton transfer events, known as the Grotthuss mechanisms. Here, we present an experimental study of the diffusion and H/D exchange of hydronium and hydroxide ions in amorphous solid water (ASW) at 140-180 K by using low-energy sputtering (LES) and temperature-programmed desorption (TPD) measurements. The study shows that the two species transport in ASW via fundamentally different molecular mechanisms. Whereas hydronium ions migrate via efficient proton transfer, hydroxide ions move via Brownian molecular diffusion without proton transfer. The molecular hydroxide diffusion in ASW is in stark contrast to the current view of the hydroxide diffusion mechanism in aqueous solution, which involves proton transfer. PMID:26277944

  5. Assessing the gas transport mechanisms in the Swiss L/ILW concept using numerical modeling and supporting experimental work

    International Nuclear Information System (INIS)

    In low/intermediate-level waste (L/ILW) repositories, anaerobic corrosion of metals and degradation of organic materials produce hydrogen, methane, and carbon dioxide. Gas accumulation and gas transport in a L/ILW repository is an important component in the safety assessment of proposed deep repositories in low-permeability formations. The dominant gas transport mechanisms are dependent on the gas overpressures as with increasing overpressure the gas transport capacity of the system increases. The dominant gas transport mechanisms occurring with increasing gas pressure within the anticipated pressure ranges are: diffusion of gas dissolved in pore water (1), two phase flow in the host rock and the excavation damaged zone (EDZ) whereby no deformation of the pore space occurs (2), gas migration within parts of the repository (if repository materials are appropriately chosen) (3) and pathway dilation (4). Under no circumstances the gas is expected to induce permanent fractures in the host rock. This paper focuses on the gas migration in parts of the repository whereby materials are chosen aimed at increasing the gas transport capacity of the backfilled underground structures without compromising the radionuclide retention capacity of the engineered barrier system (EBS). These materials with enhanced gas permeability and low water permeability can supplement the gas flow that is expected to occur through the EDZ and the host rock. The impact of the use of adapted backfill and sealing materials on the gas pressure build-up and the major gas paths were assessed using numerical two-phase flow models on the repository scale. Furthermore, both the gas and water fluxes as a function of time and gas generation rate can be evaluated by varying the physical properties of the materials and hence their transport capacity. Results showed that by introducing seals with higher gas permeability, the modelled gas flow is largely limited to the access tunnels and the excavation disturbed zone for the case of a very low permeability host rock. The bulk of the gas flows through the repository seal and the adjacent EDZ into the tunnel system. In addition to the demonstration of the gas flow in the seal and access tunnel system by numerical models, laboratory results confirm the high gas transport capacity of the sand/bentonite mixtures. In a next step a multi year demonstration scale experiment (GAST) at the Grimsel Test Site is envisioned. (author)

  6. Linking valve closure behavior and sodium transport mechanism in freshwater clam Corbicula fluminea in response to copper

    International Nuclear Information System (INIS)

    The purpose of this study is to develop a mechanistic model to describe a conceptually new 'flux-biological response' approach based on biotic ligand model (BLM) and Michaelis-Menten (M-M) kinetics to allow the linkage between valve closure behavior and sodium (Na) transport mechanism in freshwater clam Corbicula fluminea in response to waterborne copper (Cu). We test the proposed model against published data regarding Na uptake kinetics in rainbow trout and Na uptake profile in C. fluminea, confirming that the predictive model is robust. Here, we show that the predicted M-M maximum Cu internalization flux in C. fluminea is 0.369 μmol g-1 h-1 with a half-saturation affinity constant of 7.87 x 10-3 μM. Dynamics of Na uptake and valve closure daily rhythm driven by external Cu can also be predicted simultaneously. We suggest that this 'Na transport-valve closure behavior' approach might provide the basis of a future design of biomonitoring tool. - A new flux-biological response model can link valve closure and sodium transport mechanisms in freshwater clam in response to copper

  7. Carbon dioxide transport in molten calcium carbonate occurs through an oxo-Grotthuss mechanism via a pyrocarbonate anion

    Science.gov (United States)

    Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

    2016-05-01

    The reactivity, speciation and solvation structure of CO2 in carbonate melts are relevant for both the fate of carbon in deep geological formations and for its electroreduction to CO (to be used as fuel) when solvated in a molten carbonate electrolyte. In particular, the high solubility of CO2 in carbonate melts has been tentatively attributed to the formation of the pyrocarbonate anion, C2O52–. Here we study, by first-principles molecular dynamics simulations, the behaviour of CO2 in molten calcium carbonate. We find that pyrocarbonate forms spontaneously and the identity of the CO2 molecule is quickly lost through O2– exchange. The transport of CO2 in this molten carbonate thus occurs in a fashion similar to the Grotthuss mechanism in water, and is three times faster than molecular diffusion. This shows that Grotthuss-like transport is more general than previously thought.

  8. Energy transport mechanism in the form of proton soliton in a one-dimensional hydrogen-bonded polypeptide chain.

    Science.gov (United States)

    Kavitha, L; Priya, R; Ayyappan, N; Gopi, D; Jayanthi, S

    2016-01-01

    The dynamics of protons in a one-dimensional hydrogen-bonded (HB) polypeptide chain (PC) is investigated theoretically. A new Hamiltonian is formulated with the inclusion of higher-order molecular interactions between peptide groups (PGs). The wave function of the excitation state of a single particle is replaced by a new wave function of a two-quanta quasi-coherent state. The dynamics is governed by a higher-order nonlinear Schrödinger equation and the energy transport is performed by the proton soliton. A nonlinear multiple-scale perturbation analysis has been performed and the evolution of soliton parameters such as velocity and amplitude is explored numerically. The proton soliton is thermally stable and very robust against these perturbations. The energy transport by the proton soliton is more appropriate to understand the mechanism of energy transfer in biological processes such as muscle contraction, DNA replication, and neuro-electric pulse transfer on biomembranes. PMID:26198375

  9. Description of Transport Mechanism in Polymeric Membrane via Sorption in Steady State

    Czech Academy of Sciences Publication Activity Database

    Fialová, Kateřina

    Geesthacht : GKSS Research Centre, 2004 - (Castano, M.; Schipolowski, T.; Siegert, M.), s. 82-83 [Network Young Membrains 6th Meeting. Hamburg (DE), 22.09.2004-24.09.2004] R&D Projects: GA ČR GD203/03/H140; GA AV ČR IAA4072402 Institutional research plan: CEZ:AV0Z4072921 Keywords : vapor permeation * pervaporation * membrane transport Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  10. Towards the Restructuring and Co-ordination Mechanisms for the Architecture of Chinese Transport Logistics

    OpenAIRE

    Yang, Jiaqi

    2009-01-01

    textabstractWith China’s emergence as a global manufacturing centre, reshaping the country’s logistics industry is assuming a global dimension too. The Chinese transport sector, despite its tremendous potential in facilitating the economic development of the country, is plagued with problems of insufficient infrastructure; overlapping regulatory authority; operational inefficiencies and a lack of logistics culture. The thesis shows that China urgently needs to restructure the architecture of ...

  11. Uptake of waterborne tributyltin in the brain of fish: axonal transport as a proposed mechanism.

    Science.gov (United States)

    Rouleau, Claude; Xiong, Zheng-Hu; Pacepavicius, Grazina; Huang, Guo-Lan

    2003-08-01

    In previous studies, it was shown that waterborne Hg(II), Cd(II), and Mn(II) enter nerves innervating water-exposed sensory organs of fish and are transported to the brain by axonal transport. However, it is not known if organometals, such as tributyltin (TBT), can reach the brain of fish via the same route. In this work, we exposed rainbow trout (Oncorhynchus mykiss) to waterborne [113Sn]-TBT (4.2 kBq/L). Three fish were sampled after a 2-week exposure, and three others were sampled after a 2-week depuration period. Another group of four fish received an intravenous injection of [113Sn]-TBT and were sampled after 2 and 14 d. Distribution of the radiolabel was visualized and quantified by quantitative whole-body autoradiography. The brain accumulated a significant amount of 113Sn, with hot spots being found in parts receiving sensory nerves from water-exposed sensory organs, such as eminentia granulares (lateral lines organs). Labeling of the brain was also seen for i.v.-injected fish, indicating that the blood-brain barrier is not impervious to TBT or its metabolites. Nevertheless, the distribution of radioactivity in the brain was much more uniform, with no evident hot spot. Though the transfer [water --> gills --> blood stream --> blood-brain barrier --> brain] may account for a certain proportion of the radiolabel accumulation in fish brain, exposure to [113Sn]-TBT via water resulted in higher accumulation in some areas of the brain, of which the specific location strongly suggests that it was taken up in different water-exposed sensory nerve terminals and transported directly to the brain by axonal transport, as the parent compound or as a metabolite. The resulting local enhancement of the accumulation of butyltins might jeopardize the integrity of nervous system. Further work is needed to assess the toxicological significance of this process. PMID:12966973

  12. Nicotine increases dopamine transporter function in rat striatum through a trafficking-independent mechanism

    OpenAIRE

    Middleton, Lisa S.; Apparsundaram, Subbu; King-Pospisil, Kelley A.; DWOSKIN, LINDA P.

    2006-01-01

    In previous in vivo voltammetry studies, acute nicotine administration increased striatal dopamine clearance. The current study aimed to determine whether nicotine also increases [3H]dopamine uptake across the time course of the previous voltammetry studies and whether dopamine transporter trafficking to the cell surface mediates the nicotine-induced augmentation of dopamine clearance in striatum. Rats were administered nicotine (0.32 mg/kg, s.c.); striatal synaptosomes were obtained 5, 10, 4...

  13. Sensitizing Curium Luminescence through an Antenna Protein to Investigate Biological Actinide Transport Mechanisms

    OpenAIRE

    Sturzbecher-Hoehne, Manuel; Goujon, Christophe; Deblonde, Gauthier J.-P.; Mason, Anne B; Abergel, Rebecca J.

    2013-01-01

    Worldwide stocks of actinides and lanthanide fission products produced through conventional nuclear spent fuel are increasing continuously, resulting in a growing risk of environmental and human exposure to these toxic radioactive metal ions. Understanding the bio-molecular pathways involved in mammalian uptake, transport and storage of these f-elements is crucial to the development of new decontamination strategies and could also be beneficial to the design of new containment and separation ...

  14. Towards the Restructuring and Co-ordination Mechanisms for the Architecture of Chinese Transport Logistics

    OpenAIRE

    Yang, Jiaqi

    2009-01-01

    With China’s emergence as a global manufacturing centre, reshaping the country’s logistics industry is assuming a global dimension too. The Chinese transport sector, despite its tremendous potential in facilitating the economic development of the country, is plagued with problems of insufficient infrastructure; overlapping regulatory authority; operational inefficiencies and a lack of logistics culture. The thesis shows that China urgently needs to restructure the architecture of its transpor...

  15. Controlling the transport of an ion: classical and quantum mechanical solutions

    International Nuclear Information System (INIS)

    The accurate transport of an ion over macroscopic distances represents a challenging control problem due to the different length and time scales that enter and the experimental limitations on the controls that need to be accounted for. Here, we investigate the performance of different control techniques for ion transport in state-of-the-art segmented miniaturized ion traps. We employ numerical optimization of classical trajectories and quantum wavepacket propagation as well as analytical solutions derived from invariant based inverse engineering and geometric optimal control. The applicability of each of the control methods depends on the length and time scales of the transport. Our comprehensive set of tools allows us make a number of observations. We find that accurate shuttling can be performed with operation times below the trap oscillation period. The maximum speed is limited by the maximum acceleration that can be exerted on the ion. When using controls obtained from classical dynamics for wavepacket propagation, wavepacket squeezing is the only quantum effect that comes into play for a large range of trapping parameters. We show that this can be corrected by a compensating force derived from invariant based inverse engineering, without a significant increase in the operation time. (paper)

  16. Observations of Intertidal Bars Welding to the Shoreline: Examining the Mechanisms of Onshore Sediment Transport and Beach Recovery

    Science.gov (United States)

    Cohn, N.; Anderson, D. L.; Susa, T.; Ruggiero, P.; Honegger, D.; Haller, M. C.

    2014-12-01

    Many coastlines throughout the world are in a net erosional state due to factors such as climate change and anthropogenic activities. While most coastal erosion occurs episodically during major storms, beaches recover during extended periods of low wave energy. Despite the importance of beach recovery on limiting coastal vulnerability, the mechanisms driving onshore sediment transport are much less well understood than those of storm-driven offshore transport. Intertidal bar (i.e., swash bar) welding to the shoreline is one proposed mechanism of sediment delivery from the nearshore to the backshore. However, studies of swash bars and their contribution to beach building have been scarce because of the sporadic nature of these events and difficulty measuring sediment fluxes in the intertidal zone. Several beaches in the US Pacific Northwest are prograding rapidly in part due to highly dissipative conditions and an abundant sediment supply. For example, at South Beach State Park (SBSP) in Newport, OR the shoreline accreted at an average of 6 m/yr from 1960 to 2002. To explore the role of intertidal bar welding on supplying sediment to this dynamic backshore, we recently completed a boutique field experiment at SBSP. Topographic and bathymetric surveys carried out over 9 months document the short term (welding on supplying sediment to the backshore as well as the environmental conditions and physical mechanisms that promote onshore delivery of sediment.

  17. The influence of particle shape on structure, mechanics, and transport in granular materials

    Science.gov (United States)

    Smith, Kyle C.

    The development of materials with tailored transport properties is essential to energy conversion and storage applications. Utilization of heterogeneous composite materials composed of discrete particles (i.e., granular materials) represents a promising approach to sustainable, scalable materials production. The so-called jamming point, which represents the transition between fluid-like and solid-like regimes of granular materials, has been the subject of recent fundamental studies. Prior studies have incorporated highly simplified grain shapes that do not reflect the diversity commonly observed in advanced composite materials (e.g., nanomaterials). In the present work, the coupling of heat and charge transport to the level of order in jammed microstructures composed of faceted 3D grains is explored. The systems investigated include lithium ion battery cathodes composed of LiFePO4 nanoparticles, solid state H2 storage in packed beds composed of metal hydride particles, and the Platonic solids. Empirical and theoretical representations of particle shape are determined with single crystal growth models, statistical geometric models, and experimental measurements. An energy-based structural optimization method for the jamming of such arbitrary polyhedral grains is developed to model the mesoscopic structure of heterogeneous materials. Diffusion through the resulting microstructures is simulated with the finite volume method. In LiFePO4 systems a strong dependence of jamming on particle shapes is observed, in which columnar structures aligned with the [010] direction inhibit diffusion along [010] in anisotropic LiFePO4. Transport limitations are induced by [010] columnar order and lead to catastrophic performance degradation in anisotropic LiFePO4 cathodes. Further, judicious mixing of nanoplatelets with additive nanoparticles can frustrate columnar ordering and thereby enhance the rate capability of LiFePO4 electrodes by nearly an order of magnitude. In contrast, metal hydride particles (and all Platonic solids except cubes) jam into highly disordered structures, as a result of anisotropic shape and size distribution. Such systems exhibit fundamentally different pathways of heat transport than that of packed spheres and consequently display close agreement with granular effective medium theory predictions. Also, despite possessing rigidity percolation at the jamming point, conductivity percolation does not occur at the jamming point. From these initial studies it is clear that knowledge of particle shape effects on structure and transport provide a pathway for scalable, bottom-up design of materials.

  18. Carbon Footprint Management of Road Freight Transport under the Carbon Emission Trading Mechanism

    OpenAIRE

    Jin Li; Qihui Lu; Peihua Fu

    2015-01-01

    Growing concern over environmental issues has considerably increased the number of regulations and legislation that aim to curb carbon emissions. Carbon emission trading mechanism, which is one of the most effective means, has been broadly adopted by several countries. This paper presents a road truck routing problem under the carbon emission trading mechanism. By introducing a calculation method of carbon emissions that considers the load and speed of the vehicle among other factors, a road ...

  19. Mechanical properties used for the qualification of transport casks: Prototype development and extension to serial production

    International Nuclear Information System (INIS)

    A thorough understanding of the mechanical behavior of material in a specific cask is required to properly analyze the structural response of the cask. An appropriate way to establish this understanding is through laboratory testing of cask material. The laboratory testing that was done to support the MOSAIK Drop Test Program is summarized as an example of how mechanical properties can be mapped for a prototype cask. The broad range of measured properties allows the critical aspects of mechanical behavior to be understood. This is necessary for the proper application of fracture mechanics, and focuses on fracture toughness as the inherent materials property which quantifies the fracture resistance of a material. The general fracture mechanics approach and its application to specific cask designs are described elsewhere (Salzbrenner et al. 1990, Sorenson et al. 1992a, Sorenson et al. 1992b). The understanding established by a thorough mapping of the mechanical properties is necessary to apply fracture mechanics to a particular prototype, but it is not sufficient for qualifying serially produced casks. The mechanical behavior of a prototype must be correctly associated with parameters which can be measured on production casks. Since the production casks cannot be destructively tested, measurements are commonly made on sub-size specimens. This may prevent direct measurement of valid design properties. An additional database may then be required to establish the correlation between sub-size specimen measurements and valid design properties. This is illustrated by outlining the additional testing which would be necessary to allow the successful verification of the MOSAIK Drop Test Program to be extended from the prototype to serially produced casks

  20. The cytotoxicity of the α1-adrenoceptor antagonist prazosin is linked to an endocytotic mechanism equivalent to transport-P.

    Science.gov (United States)

    Fuchs, Robert; Stracke, Anika; Ebner, Nadine; Zeller, Christian Wolfgang; Raninger, Anna Maria; Schittmayer, Matthias; Kueznik, Tatjana; Absenger-Novak, Markus; Birner-Gruenberger, Ruth

    2015-12-01

    Since the α1-adrenergic antagonist prazosin (PRZ) was introduced into medicine as a treatment for hypertension and benign prostate hyperplasia, several studies have shown that PRZ induces apoptosis in various cell types and interferes with endocytotic trafficking. Because PRZ is also able to induce apoptosis in malignant cells, its cytotoxicity is a focus of interest in cancer research. Besides inducing apoptosis, PRZ was shown to serve as a substrate for an amine uptake mechanism originally discovered in neurones called transport-P. In line with our hypothesis that transport-P is an endocytotic mechanism also present in non-neuronal tissue and linked to the cytotoxicity of PRZ, we tested the uptake of QAPB, a fluorescent derivative of PRZ, in cancer cell lines in the presence of inhibitors of transport-P and endocytosis. Early endosomes and lysosomes were visualised by expression of RAB5-RFP and LAMP1-RFP, respectively; growth and viability of cells in the presence of PRZ and uptake inhibitors were also tested. Cancer cells showed co-localisation of QAPB with RAB5 and LAMP1 positive vesicles as well as tubulation of lysosomes. The uptake of QAPB was sensitive to transport-P inhibitors bafilomycin A1 (inhibits v-ATPase) and the antidepressant desipramine. Endocytosis inhibitors pitstop(®) 2 (general inhibitor of endocytosis), dynasore (dynamin inhibitor) and methyl-β-cyclodextrin (cholesterol chelator) inhibited the uptake of QAPB. Bafilomycin A1 and methyl-β-cyclodextrin but not desipramine were able to preserve growth and viability of cells in the presence of PRZ. In summary, we confirmed the hypothesis that the cellular uptake of QAPB/PRZ represents an endocytotic mechanism equivalent to transport-P. Endocytosis of QAPB/PRZ depends on a proton gradient, dynamin and cholesterol, and results in reorganisation of the LAMP1 positive endolysosomal system. Finally, the link seen between the cellular uptake of PRZ and cell death implies a still unknown pro-apoptotic membrane protein with affinity towards PRZ. PMID:26449523

  1. Development of intestinal ion-transporting mechanisms during smoltification and seawater acclimation in Atlantic salmon Salmo salar

    Science.gov (United States)

    Sundh, Henrik; Nilsen, Tom O.; Lindström, Jenny; Hasselberg-Frank, Linda; Stefansson, Sigurd O.; McCormick, Stephen D.; Sundell, K.

    2014-01-01

    This study investigated the expression of ion transporters involved in intestinal fluid absorption and presents evidence for developmental changes in abundance and tissue distribution of these transporters during smoltification and seawater (SW) acclimation of Atlantic salmonSalmo salar. Emphasis was placed on Na+, K+-ATPase (NKA) and Na+, K+, Cl− co-transporter (NKCC) isoforms, at both transcriptional and protein levels, together with transcription of chloride channel genes. The nka α1c was the dominant isoform at the transcript level in both proximal and distal intestines; also, it was the most abundant isoform expressed in the basolateral membrane of enterocytes in the proximal intestine. This isoform was also abundantly expressed in the distal intestine in the lower part of the mucosal folds. The protein expression of intestinal Nkaα1c increased during smoltification. Immunostaining was localized to the basal membrane of the enterocytes in freshwater (FW) fish, and re-distributed to a lateral position after SW entry. Two other Nka isoforms, α1a and α1b, were expressed in the intestine but were not regulated to the same extent during smoltification and subsequent SW transfer. Their localization in the intestinal wall indicates a house-keeping function in excitatory tissues. The absorptive form of the NKCC-like isoform (sub-apically located NKCC2 and/or Na+, Cl−co-transporter) increased during smoltification and further after SW transfer. The cellular distribution changed from a diffuse expression in the sub-apical regions during smoltification to clustering of the transporters closer to the apical membrane after entry to SW. Furthermore, transcript abundance indicates that the mechanisms necessary for exit of chloride ions across the basolateral membrane and into the lateral intercellular space are present in the form of one or more of three different chloride channels: cystic fibrosis transmembrane conductance regulator I and II and chloride channel 3.

  2. Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca2+ release

    Directory of Open Access Journals (Sweden)

    Thomas E. Jensen

    2014-10-01

    Full Text Available Understanding how muscle contraction orchestrates insulin-independent muscle glucose transport may enable development of hyperglycemia-treating drugs. The prevailing concept implicates Ca2+ as a key feed forward regulator of glucose transport with secondary fine-tuning by metabolic feedback signals through proteins such as AMPK. Here, we demonstrate in incubated mouse muscle that Ca2+ release is neither sufficient nor strictly necessary to increase glucose transport. Rather, the glucose transport response is associated with metabolic feedback signals through AMPK, and mechanical stress-activated signals. Furthermore, artificial stimulation of AMPK combined with passive stretch of muscle is additive and sufficient to elicit the full contraction glucose transport response. These results suggest that ATP-turnover and mechanical stress feedback are sufficient to fully increase glucose transport during muscle contraction, and call for a major reconsideration of the established Ca2+ centric paradigm.

  3. Analysis and further development of fracture mechanics failure concepts. Main topic: Application of the J integral concept and its extensions on component-relevant situations

    International Nuclear Information System (INIS)

    In many investigations with increasingly complex conditions of use, the concepts of elastic/plastic fracture mechanics and particularly the J integral concept for the quantitative evaluation of failure behaviour have proved successful. This was proved in this project by largely clearing up the effects of constraint in the environment of cracks and the use of the J integral concept with superimposed thermal and mechanical stresses which can occur in thermal shock transients important for safety analysis. In continuing the investigations of dynamic JR curves, it was confirmed that the tendency to form auxiliary cracks and therefore to raise the crack resistance curve increases with the stress parameters and also with the size of the sample. Here and in investigations on the effect of large crack widths on quickly loaded disks with side cracks caused some difficulties. The improvement of the J integral calculation aimed at by correction terms could not be satisfactorily achieved. One way out is the crack energy to describe great extensions of cracks. (orig.)

  4. Monitoring and modelling of thermo-hydro-mechanical processes - main results of a heater experiment at the Mont Terri underground rock laboratory

    International Nuclear Information System (INIS)

    The long-term safety of permanent underground repositories relies on a combination of engineered and geological barriers, so that the interactions between the barriers in response to conditions expected in a high-level waste repository need to be identified and fully understood. Co-financed by the European Community, a heater experiment was realized on a pilot plant scale at the underground laboratory in Mont Terri, Switzerland. The experiment was accompanied by an extensive programme of continuous monitoring, experimental investigations on-site as well as in laboratories, and numerical modelling of the coupled thermo-hydro-mechanical processes. Heat-producing waste was simulated by a heater element of 10 cm diameter, held at a constant surface temperature of 100 C. The heater element (length 2 m) operated in a vertical borehole of 7 m depth at 4 to 6 m depth. It was embedded in a geotechnical barrier of pre-compacted bentonite blocks (outer diameter 30 cm) that were irrigated for 35 months before the heating phase (duration 18 months) began. The host rock is a highly consolidated stiff Jurassic clay stone (Opalinus Clay). After the heating phase, the vicinity of the heater element was explored by seismic, hydraulic, and geotechnical tests to investigate if the heating had induced changes in the Opalinus Clay. Additionally, rock mechanic specimens were tested in the laboratory. Finally, the experiment was dismantled to provide laboratory specimens of post - heating buffer and host rock material. The bentonite blocks were thoroughly wetted at the time of the dismantling. The volume increase amounted to 5 to 9% and was thus below the bentonite potential. Geo-electrical measurements showed no decrease of the water content in the vicinity of the heater during the heating phase. Decreasing energy input to the heater element over time suggests hence, that the bentonite dried leading to a decrease of its thermal conductivity. Gas release during the heating period occurred most pronouncedly in a borehole closest to the heater (0.5 m), where after an incubation period of about 6 months after the beginning of heating bell-shaped release curves of carbon dioxide and hydrogen sulphide developed over 10 months indicating that chemical reactions in the Opalinus Clay are restricted. Metal corrosion caused by Opalinus Clay (as it occurred in the rock mechanic laboratory) is probably restricted as well by the supply of a reactant such as oxygen. Gas release data also suggest that the gas permeability of the Opalinus Clay may be inhomogeneous. Bentonite and Opalinus Clay show only very weak modifications induced by the heater experiment. Numerical calculations were done with axisymmetric as well as with anisotropic models. The input data for the anisotropic properties of the Opalinus Clay were provided by the rock mechanic tests. Data of anisotropic creep properties were determined in the laboratory and integrated in a Burgers model (but have not yet been used in the Finite Element modeling). Mineralogical analysis shows that the mechanical properties of the Opalinus Clay depend on microstructure rather than mineralogy. The match between monitored and calculated time series of temperature and pore pressure is good. The pore pressure development shows the impact of transition processes in the Opalinus Clay caused b y watering of the bentonite, heating, and cooling. The hydraulic conductivity has considerable influence on the magnitude of the pore pressure values. The long-term steady stress field does not appear to be affected by the heating and cooling. The bentonite blocks insulate the heater element so that the host rock was only moderately heated (about 65 C at the interface buffer-rock). The temperature field extended to a maximum radial distance of about 5 m only. (authors)

  5. Monitoring and modelling of thermo-hydro-mechanical processes - main results of a heater experiment at the Mont Terri underground rock laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Ingeborg, G.; Alheid, H.J. [BGR - Federal Institute for Geosciences and Natural Resources, Hannover (Germany); Jockwerz, N. [Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS) - Final Repository Research Division, Braunschweig (Germany); Mayor, J.C. [ENRESA - Empresa Nacional des Residuos Radioactivos, Madrid (Spain); Garcia-Siner, J.L. [AITEMIN -Asociacion para la Investigacion y Desarrollo Industrial de los Recursos Naturales, Madrid, (Spain); Alonso, E. [CIMNE - Centre Internacional de Metodos Numerics en Ingenyeria, UPC, Barcelona (Spain); Weber, H.P. [NAGRA - National Cooperative for the Disposal of Radioactive Waste, Wettingen (Switzerland); Plotze, M. [ETHZ - Swiss Federal Institute of Technology Zurich, IGT, Zurich, (Switzerland); Klubertanz, G. [COLENCO Power Engineering Ltd., Baden (Switzerland)

    2005-07-01

    The long-term safety of permanent underground repositories relies on a combination of engineered and geological barriers, so that the interactions between the barriers in response to conditions expected in a high-level waste repository need to be identified and fully understood. Co-financed by the European Community, a heater experiment was realized on a pilot plant scale at the underground laboratory in Mont Terri, Switzerland. The experiment was accompanied by an extensive programme of continuous monitoring, experimental investigations on-site as well as in laboratories, and numerical modelling of the coupled thermo-hydro-mechanical processes. Heat-producing waste was simulated by a heater element of 10 cm diameter, held at a constant surface temperature of 100 C. The heater element (length 2 m) operated in a vertical borehole of 7 m depth at 4 to 6 m depth. It was embedded in a geotechnical barrier of pre-compacted bentonite blocks (outer diameter 30 cm) that were irrigated for 35 months before the heating phase (duration 18 months) began. The host rock is a highly consolidated stiff Jurassic clay stone (Opalinus Clay). After the heating phase, the vicinity of the heater element was explored by seismic, hydraulic, and geotechnical tests to investigate if the heating had induced changes in the Opalinus Clay. Additionally, rock mechanic specimens were tested in the laboratory. Finally, the experiment was dismantled to provide laboratory specimens of post - heating buffer and host rock material. The bentonite blocks were thoroughly wetted at the time of the dismantling. The volume increase amounted to 5 to 9% and was thus below the bentonite potential. Geo-electrical measurements showed no decrease of the water content in the vicinity of the heater during the heating phase. Decreasing energy input to the heater element over time suggests hence, that the bentonite dried leading to a decrease of its thermal conductivity. Gas release during the heating period occurred most pronouncedly in a borehole closest to the heater (0.5 m), where after an incubation period of about 6 months after the beginning of heating bell-shaped release curves of carbon dioxide and hydrogen sulphide developed over 10 months indicating that chemical reactions in the Opalinus Clay are restricted. Metal corrosion caused by Opalinus Clay (as it occurred in the rock mechanic laboratory) is probably restricted as well by the supply of a reactant such as oxygen. Gas release data also suggest that the gas permeability of the Opalinus Clay may be inhomogeneous. Bentonite and Opalinus Clay show only very weak modifications induced by the heater experiment. Numerical calculations were done with axisymmetric as well as with anisotropic models. The input data for the anisotropic properties of the Opalinus Clay were provided by the rock mechanic tests. Data of anisotropic creep properties were determined in the laboratory and integrated in a Burgers model (but have not yet been used in the Finite Element modeling). Mineralogical analysis shows that the mechanical properties of the Opalinus Clay depend on microstructure rather than mineralogy. The match between monitored and calculated time series of temperature and pore pressure is good. The pore pressure development shows the impact of transition processes in the Opalinus Clay caused b y watering of the bentonite, heating, and cooling. The hydraulic conductivity has considerable influence on the magnitude of the pore pressure values. The long-term steady stress field does not appear to be affected by the heating and cooling. The bentonite blocks insulate the heater element so that the host rock was only moderately heated (about 65 C at the interface buffer-rock). The temperature field extended to a maximum radial distance of about 5 m only. (authors)

  6. Transport function and reaction mechanism of vacuolar H{sup +}- translocation inorganic pyrophosphatase. Annual technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    These studies describe progress made in the definition of the transport capabilities and reaction mechanism of the V-PPase through biochemical analyses of native membrane vesicles isolated from etiolated hypocotyls of Vigna radiate and by reconstitution of the purified enzyme into artificial liposomes; delineation of the ligand requirements of the V-PPase; and the delineation of sequence motifs implicated in substrate-binding through the development of strategies for selective cleavage of the M{sub r} 66,000 polypeptide and the mapping of covalently modified peptide fragments.

  7. Panorama 2013 - Air transport and the problem of CO2: ETS mechanisms and bio-jet fuels

    International Nuclear Information System (INIS)

    Air transport currently accounts for only 2% (∼600 Mt/year) of global CO2 emissions from human activity. Despite this 2% level, this industry is targeted by governments - especially European Union - and initiatives targeting zero growth in carbon from 2020 onwards, and a 50% reduction by 2050. Over and above aircraft technical innovations and the way in which air traffic is organised, the introduction of ETS (Emissions Trading System) mechanisms and the development of bio-jet fuels are the options most commonly cited in discussions on how to achieve that target. (author)

  8. Mechanisms of meridional transport processes in the tropical Atlantic; Mechanismen meridionaler Transportprozesse im tropischen Atlantik

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, J.

    2001-07-01

    Meridional transport processes of water masses and tracers in the subtropical and tropical Atlantic are investigated using a regional eddy resolving model of the wind driven and thermohaline circulation. Analytical emphasis is on float simulations in the model which, complementary to Eulerian means, represent the Lagrangian view and give further insight into the spreading and pathways of characteristic water masses in this area. In the tropics and subtropics shallow 3-dimensional circulation cells are superimposed on the northward warm water transfer within the deep reaching thermohaline overturning cell (MOC) as part of the global ''Conveyor Belt''. Under present-day climate conditions the model shows that the equatorial thermocline is exclusively ventilated by subsurface flow within the tropical-subtropical cell (STC) of the South Atlantic. Only with a prescribed ''Conveyor-off''-Mode the STC of the North Atlantic contributes to this ventilation process with equal amounts. Throughout the year the interhemispheric transport of surface and central water masses of South Atlantic origin into the Caribbean Sea is dominated by zonal detours to the east as a consequence of the interplay of several retroflection events occuring in the North Atlantic. The eulerian mean flow field in the deep layer postulates the interhemispheric mass transport into the South Atlantic to be confined entirely to the western boundary, whereas Lagrangian means indicate intermittent eastward excursions along the equator, related to seasonally alternating zonal currents due to long Rossby waves. It was suggested that the observed characteristic eastward maximum of tracer concentrations along the equator is a consequence of rectifying effects of single or interacting equatorial waves. The model does not validate this hypothesis. The response to transport anomalies of subpolar origin and long periodicity is subject to different time-scales in both hemispheres. The fast response is confined to the northern hemisphere and dominates the first two years because of the mediating waves which at first propagate only around the North Atlantic basin. After 8 to 10 years the changes in the overturning are not restricted to the North anymore but are apparent in both hemispheres. (orig.)

  9. Understanding of pairing mechanism and transport properties in double energy gap superconductors: MgB2

    International Nuclear Information System (INIS)

    It is intended to trace the evolution of an effective dynamic interaction embodying the screening of electrons by optical phonons and plasmons. A model dielectric function is set up for MgB2 with two energy gaps following realistic sum rules on electronic (ionic) polarizabilities. Developing this scheme within strong coupling theory, Tc is estimated as 40 K and energy gap ratio is larger than BCS value. The isotope exponent, pressure effect and magnetic penetration depth are also estimated. The transport properties as electrical resistivity, thermal conductivity, thermoelectric power and optical conductivity are discussed with both ?and ? carriers in MgB2. (author)

  10. A Molecular Mechanism for Copper Transportation to Tyrosinase That Is Assisted by a Metallochaperone, Caddie Protein*

    OpenAIRE

    Matoba, Yasuyuki; Bando, Naohiko; Oda, Kosuke; Noda, Masafumi; Higashikawa, Fumiko; KUMAGAI, Takanori; Sugiyama, Masanori

    2011-01-01

    The Cu(II)-soaked crystal structure of tyrosinase that is present in a complex with a protein, designated “caddie,” which we previously determined, possesses two copper ions at its catalytic center. We had identified two copper-binding sites in the caddie protein and speculated that copper bound to caddie may be transported to the tyrosinase catalytic center. In our present study, at a 1.16–1.58 Å resolution, we determined the crystal structures of tyrosinase complexed with caddie prepared by...

  11. The solar neutrino problem: limitations of energy transport by mechanical means

    International Nuclear Information System (INIS)

    The thermodynamic limitations of energy transfer by mechanical means in the solar core are examined in the context of the solar neutrino problem. Under the hypothesis that thermal energy is converted into mechanical energy in the nuclear-burning core of the sun, it is possible to find steady-state solar models with very low neutrino counting rates. However, the efficiencies required in the conversion of thermal into mechanical energy are very close to the maximum possible value given by Carnot's theorem. Moreover, these models are very helium-poor (Xi approximately < 0.84) since an adjustment of the initial composition is necessary to compensate for the overall decrease of the opacity. It is then quite unlikely that energy transfer by mechnaical means in the central regions of the sun can resolve the solar neutrino puzzle. (orig.)

  12. Seismic valve as the main mechanism for sedimentary fluid entrapment within extensional basin: example of the Lodve Permian Basin (Hrault, South of France).

    Science.gov (United States)

    Laurent, D.; Lopez, M.; Chauvet, A.; Imbert, P.; Sauvage, A. C.; Martine, B.; Thomas, M.

    2014-12-01

    During syn-sedimentary burial in basin, interstitial fluids initially trapped within the sedimentary pile are easily moving under overpressure gradient. Indeed, they have a significant role on deformation during basin evolution, particularly on fault reactivation. The Lodve Permian Basin (Hrault, France) is an exhumed half graben with exceptional outcrop conditions providing access to barite-sulfides mineralized systems and hydrocarbon trapped into rollover faults of the basin. Architectural studies shows a cyclic infilling of fault zone and associated S0-parallel veins according to three main fluid events during dextral/normal faulting. Contrasting fluid entrapment conditions are deduced from textural analysis, fluid inclusion microthermometry and sulfide isotope geothermometer: (i) the first stage is characterized by an implosion breccia cemented by silicifications and barite during abrupt pressure drop within fault zone; (ii) the second stage consists in succession of barite ribbons precipitated under overpressure fluctuations, derived from fault-valve action, with reactivation planes formed by sulphide-rich micro-shearing structures showing normal movement; and (iii) the third stage is associated to the formation of dextral strike-slip pull-apart infilling by large barite crystals and contemporary hydrocarbons under suprahydrostatic pressure values. Microthermometry, sulfide and strontium isotopic compositions of the barite-sulfides veins indicate that all stages were formed by mixing between deep basinal fluids at 230C, derived from cinerite dewatering, and formation water from overlying sedimentary cover channelized trough fault planes. We conclude to a polyphase history of fluid trapping during Permian synrift formation of the basin: (i) a first event, associated with the dextral strike-slip motion on faults, leads to a first sealing of the fault zone; (ii) periodic reactivations of fault planes and bedding-controlled shearing form the main mineralized ore bodies by the single action of fluid overpressure fluctuations, undergoing changes in local stress distribution and (iii) a final tectonic activation of fault linked to last basinal fluid and hydrocarbon migration during which shear stress restoration on fault plane is faster than fluid pressure build-up.

  13. Visualization of TlBr ionic transport mechanism by the Accelerated Device Degradation technique

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Amlan, E-mail: datta@capesym.com [CapeSym, Inc., Natick, MA 01760 (United States); Becla, Piotr [CapeSym, Inc., Natick, MA 01760 (United States); Massachusetts Institute of Technology, Materials Processing Center, Cambridge, MA 02139 (United States); Motakef, Shariar [CapeSym, Inc., Natick, MA 01760 (United States)

    2015-06-01

    Thallium Bromide (TlBr) is a promising gamma radiation semiconductor detector material. However, it is an ionic semiconductor and suffers from polarization. As a result, TlBr devices degrade rapidly at room temperature. Polarization is associated with the flow of ionic current in the crystal under electrical bias, leading to the accumulation of charged ions at the device's electrical contacts. We report a fast and reliable direct characterization technique to identify the effects of various growth and post-growth process modifications on the polarization process. The Accelerated Device Degradation (ADD) characterization technique allows direct observation of nucleation and propagation of ionic transport channels within the TlBr crystals under applied bias. These channels are observed to be initiated both directly under the electrode as well as away from it. The propagation direction is always towards the anode indicating that Br{sup −} is the mobile diffusing species within the defect channels. The effective migration energy of the Br{sup −} ions was calculated to be 0.33±0.03 eV, which is consistent with other theoretical and experimental results. - Highlights: • A new technique was developed to visualize the ionic transport phenomena in TlBr. • Tl-rich defects nucleate under cathode and propagates through bulk to the anode. • Migration energy of Br{sup −} ions in TlBr was calculated to be 0.33 eV.

  14. Visualization of TlBr ionic transport mechanism by the Accelerated Device Degradation technique

    International Nuclear Information System (INIS)

    Thallium Bromide (TlBr) is a promising gamma radiation semiconductor detector material. However, it is an ionic semiconductor and suffers from polarization. As a result, TlBr devices degrade rapidly at room temperature. Polarization is associated with the flow of ionic current in the crystal under electrical bias, leading to the accumulation of charged ions at the device's electrical contacts. We report a fast and reliable direct characterization technique to identify the effects of various growth and post-growth process modifications on the polarization process. The Accelerated Device Degradation (ADD) characterization technique allows direct observation of nucleation and propagation of ionic transport channels within the TlBr crystals under applied bias. These channels are observed to be initiated both directly under the electrode as well as away from it. The propagation direction is always towards the anode indicating that Br− is the mobile diffusing species within the defect channels. The effective migration energy of the Br− ions was calculated to be 0.33±0.03 eV, which is consistent with other theoretical and experimental results. - Highlights: • A new technique was developed to visualize the ionic transport phenomena in TlBr. • Tl-rich defects nucleate under cathode and propagates through bulk to the anode. • Migration energy of Br− ions in TlBr was calculated to be 0.33 eV

  15. Numerical simulation of the tumor interstitial fluid transport: Consideration of drug delivery mechanism.

    Science.gov (United States)

    Moghadam, Mohammad Charjouei; Deyranlou, Amin; Sharifi, Alireza; Niazmand, Hamid

    2015-09-01

    The interstitial fluid transport plays an important role in terms of its effect on the delivery of therapeutic agents to the cancerous organs. In this study, a comprehensive numerical simulation of the interstitial fluid transport establishing 3D models of tumor and normal tissue is accomplished. Different shapes of solid tumors and their surrounding normal tissues are selected, by employing the porous media model and incorporating Darcy's model and Starling's law. Besides, effects of the tumor radius, normal tissue size, tissue hydraulic conductivity and necrotic core are investigated on the interstitial fluid pressure (IFP) and interstitial fluid velocity (IFV). Generally, results suggest that the configurations of the tumor and surrounding normal tissue affect IFP and IFV distributions inside the interstitium, which are much more pronounced for various configuration of the tumor. Furthermore, findings demonstrate that larger tumors are more prone for producing elevated IFP comparing with the smaller ones and impress both IFP and IFV dramatically. Nevertheless, normal tissue size has less impact on IFP and IFV, until its volume ratio to the tumor remains greater than unity; conversely, for the values lower than unity the variations become more significant. Finally, existence of necrotic core and its location in the tumor interstitium alters IFP and IFV patterns and increases IFV, considerably. PMID:26122936

  16. [Transplacental transport mechanisms of drugs for transplacental treatment of fetal tachyarrhythmia of MDCKII/MDCKII-BCRP cell line].

    Science.gov (United States)

    Wang, Wei; Zhao, Jia-jia; Wang, Ting; Wang, Ling; Jiang, Xue-hua

    2015-03-01

    To study the transport mechanisms of drugs for transplacental treatment of fetal tachyarrhythmia, MDCKII-BCRP and MDCKII cell models was used. MDCKII-BCRP and MDCKII cell monolayer model was used to investigate the bi-direction transport of sotalol, propranolol, propafenone, procainamide and flecainide. Drug concentrations were measured by HPLC-UV or chemiluminescence. The apparent permeability coefficient (P(app)), efflux rate (R(E)) and net efflux rate (R(net)) were calculated. Drugs with R(net) greater than 1.5 were further investigated using cellular accumulation experiments with or without a BCRP inhibitor. The R(net) of sotalol, propranolol, propafenone and procainamide were less than 1.5, while R(net) of flecainide with concentrations of 20 and 5 ?mol x L(-1) were 1.6 and 1.9, respectively. The results showed that the transport of flecainide on MDCKII-BCRP cell monolayer could be mediated by BCRP; and the affinity increased when the concentration of flecainide decreased. Cellular accumulation experiments further suggested that accumulation of flecainide in MDCKII-BCRP cells was significantly lower than that in MDCKII cells in a concentration-dependent manner. BCRP inhibitor quercetin (50 ?mol x L(-1)) significantly increased the accumulation of flecainide in MDCKII-BCRP cells (P flecainide but not sotalol, propranolol, propafenone or procainamide can be a substrate of BCRP. Thus the effect of flecainide may be affected by the BCRP in the maternal placental trophoblast membrane layer when treating fetal tachyarrhythmia. PMID:26118109

  17. MANGANESE AS ESSENTIAL AND TOXIC ELEMENT FOR PLANTS: TRANSPORT, ACCUMULATION AND RESISTANCE MECHANISMS

    OpenAIRE

    R Millaleo; M Reyes- Diaz; A.G Ivanov; M.L Mora; Alberdi, M.

    2010-01-01

    Manganese is an essential element for plants, intervening in several metabolic processes, mainly in photosynthesis and as an enzyme antioxidant-cofactor. Nevertheless, an excess of this micronutrient is toxic for plants. Mn phytotoxicity is manifested in a reduction of biomass and photosynthesis, and biochemical disorders such as oxidative stress. Some studies on Mn toxicity and Mn translocation from soil to plant cells in Mn2+ form have demonstrated their importance under low pH and redox po...

  18. Mechanical properties used for the qualification of transport casks: Prototype development and extension to serial production

    International Nuclear Information System (INIS)

    A thorough understanding of the mechanical behavior of material in a specific cask is required to properly analyze the structural response of the cask. An appropriate way to establish this understanding is through laboratory testing of cask material. The laboratory testing that was done to support the MOSAIK Drop Test Program is summarized as an example of how mechanical properties can be mapped for a prototype cask. The broad range behavior to be understood. This is necessary for the proper application of fracture mechanics, and focuses on fracture toughness as the inherent materials property which quantifies the fracture resistance of a material. The understanding established by a mechanics to a particular prototype, behavior of a prototype must be correctly associated with parameters which can be measured on production casks. Since the production casks cannot be destructively tested, measurements are commonly made on sub-size specimens. This may prevent direct measurement of valid design properties. An additional database may then be required to establish the correlation between sub-size specimen measurements and valid design properties. This is illustrated by outlining the additional testing which would be necessary to allow the successful verification of the MOSAIK Drop Test Program to be extended from the prototype to serially produced casks

  19. The effect of mechanical twisting on oxygen ionictransport in solid-state energy conversionmembranes.

    Science.gov (United States)

    Shi, Yanuo; Bork, Alexander Hansen; Schweiger, Sebastian; Rupp, Jennifer Lilia Marguerite

    2015-07-01

    Understanding 'electro-chemo-mechanics' in oxygen ion conducting membranes represents a foundational step towards new energy devices such as micro fuel cells and oxygen or fuel separation membranes. For ionic transport in macro crystalline electrolytes, doping is conventionally used to affect oxygen ionic association/migration energies. Recently, tuning ionic transport in films through lattice strain conveyed by substrates or heterostructures has generated much interest. However, reliable manipulation of strain states to twist the ionic conduction in real micro energy devices remains intractable. Here, we demonstrate that the oxygen ionic conductivity clearly correlates with the compressive strain energy acting on the near order of the electrolyte lattices by comparing thin-film ceria-based membrane devices against substrate-supported flat structures. It is possible to capitalize on this phenomenon with a smart choice of strain patterns achieved through microelectrode design. We highlight the importance of electro-chemo-mechanics in the electrolyte material for the next generation of solid-state energy conversion microdevices. PMID:26076303

  20. Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France)

    International Nuclear Information System (INIS)

    With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium (234U et 238U), thorium (230Th et 232Th), 226Ra and 222Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during α-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and α-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

  1. Atypical Dopamine Uptake Inhibitors that Provide Clues About Cocaine's Mechanism at the Dopamine Transporter

    Science.gov (United States)

    Hauck Newman, Amy; Katz, Jonathan L.

    The dopamine transporter (DAT) has been a primary target for cocaine abuse/addiction medication discovery. However predicted addiction liability and limited clinical evaluation has provided a formidable challenge for development of these agents for human use. The unique and atypical pharmacological profile of the benztropine (BZT) class of dopamine uptake inhibitors, in preclinical models of cocaine effects and abuse, has encouraged further development of these agents. Moreover, in vivo studies have challenged the original DAT hypothesis and demonstrated that DAT occupancy and subsequent increases in dopamine produced by BZT analogues are significantly delayed and long lasting, as compared to cocaine. These important and distinctive elements are critical to the lack of abuse liability among BZT analogues, and improve their potential for development as treatments for cocaine abuse and possibly other neuropsychiatric disorders.

  2. Mechanisms of energetic efficiency in the transportation sector: environmental impacts and reflections in final energy consumption: PNE 2030; Mecanismos de eficiencia energetica no setor de transportes: impactos ambientais e os reflexos no consumo final de energia: PNE 2030

    Energy Technology Data Exchange (ETDEWEB)

    Berni, Mauro Donizeti [Universidade Estadual de Campinas (NIPE/UNICAMP), SP (Brazil). Nucleo Interdisciplinar de Planejamento Energetico], email: mauro_berni@nipeunicamp.org.br; Dorileo, Ivo Leandro [Universidade Federal do Mato Grosso (NIEPE/UFMT), Cuiaba, MT (Brazil). Nucleo Interdisciplinar de Estudos em Planejamento Energetico; Perez, Andrea Juliana Ortiz [Universidade Estadual de Campinas (DE/FEM/UNICAMP), SP (Brazil). Dept. de Energia. Fac. de Engenharia Mecanica; Paccola, Jose Angelo; Silva Junior, Herculano Xavier da; Bernardes, Cyro Barbosa [MCPAR Engenharia, Campinas, SP (Brazil)

    2010-07-01

    This work presents an energy efficiency mechanisms analysis in the Brazilian transport sector. Significant energy savings can be made in this sector and rely on urgent widespread implementation of mechanisms. The experience of the developed countries serves as base for the critical evaluation of the Brazilian situation, considering the current technological period, the investments and initiatives to reduce CO{sub 2} emissions. (author)

  3. Comparative study of electron transport mechanisms in epitaxial and polycrystalline zinc nitride films

    Science.gov (United States)

    Cao, Xiang; Yamaguchi, Yuuki; Ninomiya, Yoshihiko; Yamada, Naoomi

    2016-01-01

    Zn3N2 has been reported to have high electron mobility even in polycrystalline films. The high mobility in polycrystalline films is a striking feature as compared with group-III nitrides. However, the origins of the high mobility have not been elucidated to date. In this paper, we discuss the reason for high mobility in Zn3N2. We grew epitaxial and polycrystalline films of Zn3N2. Electron effective mass (m*) was determined optically and found to decrease with a decrease in electron density. Using a nonparabolic conduction band model, the m* at the bottom of the conduction band was derived to be (0.08 ± 0.03)m0 (m0 denotes the free electron mass), which is comparable to that in InN. Optically determined intra-grain mobility (μopt) in the polycrystalline films was higher than 110 cm2 V-1 s-1, resulting from the small m*. The Hall mobility (μH) in the polycrystalline films was significantly smaller than μopt, indicating that electron transport is impeded by scattering at the grain boundaries. Nevertheless, μH higher than 70 cm2 V-1 s-1 was achievable owing to the beneficial effect of the high μopt. As for the epitaxial films, we revealed that electron transport is hardly affected by grain boundary scattering and is governed solely by ionized impurity scattering. The findings in this study suggest that Zn3N2 is a high-mobility semiconductor with small effective mass.

  4. Transport mechanisms and rates for long lived Chernobyl deposits in mid-Wales

    International Nuclear Information System (INIS)

    The deposition and transport of 134Cs and 137Cs derived from Chernobyl within 3 upland catchments in mid-Wales (Upper Severn, Wye and Rheidol) has been examined between 1987-1989. An increase in the pre-existing inventory of 137Cs of 15% was observed. During the study period all fluvial outputs of 134Cs and 137Cs were in association with suspended and bedload sediments with no radiocaesium being detectable in solute form. The major source of 137Cs on suspended sediments was ''old'' 137Cs originating from fallout due to nuclear weapons testing. Mineral magnetic measurements combined with radiometric data suggest that the Chernobyl component in association with suspended sediments originates from top-soil sediment sources whilst the fine particulate material in association with bedload is supplied from subsurface and channel sources. Outputs of Chernobyl-labelled sediments from the catchments indicated by river and lake sampling were low. In 1988 ?0.08% of the soil inventory of Chernobyl derived radiocaesium was removed from the Wye and Severn catchments via fluvial transport, whilst between January and August 1989 ?0.04% was removed. Lake sediment inventories in Llyn Llygad Rheidol also suggest that rates of transfer across the upper Rheidol catchment are low. Sampling of the Hafren Forest indicates ?0.01 GBq of 137Cs and ?0.006 GBq of 134Cs deposited due to the Chernobyl accident is stored in the canopy of the forest. Losses to the forest floor from a Norway Spruce canopy were 13% and 15% of the activity contained in the overlying canopy in 1988 and 1989 and 16.5% and 9% in 1988 and 1989 under Sitka Spruce. (author)

  5. Effect of chlordecone (Kepone) on calcium transport mechanisms in rat heart sarcoplasmic reticulum.

    Science.gov (United States)

    Kodavanti, P R; Cameron, J A; Yallapragada, P R; Desaiah, D

    1990-09-01

    Previous studies from our laboratory have indicated that chlordecone (Kepone CD), an organochlorine insecticide, inhibited cardiac sodium pump activity and catecholamine uptake suggesting that CD may interfere with cardiac function. Sarcoplasmic reticulum (SR) calcium pump has an important role in myocardial contraction and relaxation, besides Na+ transport. Since CD interferes with cardiac Na+ ion translocases, we have studied CD effects on cardiac SR calcium pump activity. Experiments were carried out both in vitro and in vivo. SR was isolated from heart ventricles of male Sprague-Dawley rats. Cardiac SR Ca2(+)-ATPase. 45Ca-uptake and cAMP as well as calmodulin (CaM) dependent protein phosphorylation were measured. Ca2(+)-ATPase was differentiated into low affinity and high affinity forms by measuring the activity using 50 and 0.7 microM free Ca2(+)-respectively. CD in vitro inhibited 45Ca-uptake by SR in a concentration dependent manner with an IC50 value of 7 microM and SR 45Ca-uptake was totally inhibited at 20-30 microM CD. In agreement with this, both high affinity and low affinity Ca2(+)-ATPases, which are involved in Ca2+ transport across membranes, were also inhibited by CD in a concentration dependent manner with IC50 values of 0.7 and 3.2 microM respectively. Both Ca2(+)-ATPase and 45Ca-uptake by cardiac SR were significantly lower in rats treated with CD (25, 50 or 75 mg/kg) when compared to control rats. cAMP as well as CaM significantly elevated the 32P-binding to SR proteins in vitro to about 70-80%. In the presence of CD, this 32P-binding was reduced, however, not concentration dependent.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1701552

  6. Transport mechanism in ambipolar pentacene organic thin film transistors with lithium fluoride gate dielectric

    Science.gov (United States)

    Rahimi, R.; Korakakis, D.

    2011-07-01

    The electrical properties of organic thin film transistors (OTFTs) based on pentacene as the active layer and lithium fluoride (LiF) as the gate dielectric layer were investigated. Fabricated devices exhibited ambipolar behavior that can be controlled by the applied source, drain and gate biases. It was found that at low source-drain biases, multistep hopping is the dominant conduction mechanism, whereas in high voltage regimes, I-V data fits in the Fowler-Nordheim (FN) tunneling model. The relationship between the applied gate bias and the field enhancement factor, which is the ratio of the local surface electric field to the applied electric field, were determined from the slope of the FN plots. The dependency between the transition points in conduction mechanism upon gate bias has also been extracted from the FN plots. The transition points show more dependency on gate voltage for negative biases compared to the positive biases.

  7. Chaotic Advection at the Pore Scale: Mechanisms, Upscaling and Implications for Macroscopic Transport

    CERN Document Server

    Lester, D R; Metcalfe, Guy

    2016-01-01

    The macroscopic spreading and mixing of solute plumes in saturated porous media is ultimately controlled by processes operating at the pore scale. Whilst the conventional picture of pore-scale mechanical dispersion and molecular diffusion leading to persistent hydrodynamic dispersion is well accepted, this paradigm is inherently two-dimensional (2D) in nature and neglects important three-dimensional (3D) phenomena. We discuss how the kinematics of steady 3D flow at the porescale generate chaotic advection, involving exponential stretching and folding of fluid elements,the mechanisms by which it arises and implications of microscopic chaos for macroscopic dispersion and mixing. Prohibited in steady 2D flow due to topological constraints, these phenomena are ubiquitous due to the topological complexity inherent to all 3D porous media. Consequently 3D porous media flows generate profoundly different fluid deformation and mixing processes to those of 2D flow. The interplay of chaotic advection and broad transit t...

  8. Designing and testing regenerative pulp treatment strategies: modeling the transdentinal transport mechanisms

    OpenAIRE

    Passos, Agathoklis D.; Mouza, Aikaterini A.; Paras, Spiros V.; Gogos, Christos; Tziafas, Dimitrios

    2015-01-01

    The need for simulation models to thoroughly test the inflammatory effects of dental materials and dentinogenic effects of specific signaling molecules has been well recognized in current dental research. The development of a model that simulates the transdentinal flow and the mass transfer mechanisms is of prime importance in terms of achieving the objectives of developing more effective treatment modalities in restorative dentistry. The present protocol study is part of an ongoing investiga...

  9. Mechanism of the Citrate Transporters in Carbohydrate and Citrate Cometabolism in Lactococcus and Leuconostoc Species

    OpenAIRE

    Bandell, M.; Lhotte, M. E.; Marty-Teysset, C; Veyrat, A.; Prvost, H.; Dartois, V.; Divis, C; Konings, W. N.; Lolkema, J. S.

    1998-01-01

    Citrate metabolism in the lactic acid bacterium Leuconostoc mesenteroides generates an electrochemical proton gradient across the membrane by a secondary mechanism (C. Marty-Teysset, C. Posthuma, J. S. Lolkema, P. Schmitt, C. Divies, and W. N. Konings, J. Bacteriol. 178:21782185, 1996). Reports on the energetics of citrate metabolism in the related organism Lactococcus lactis are contradictory, and this study was performed to clarify this issue. Cloning of the membrane potential-generating c...

  10. Mechanisms for lithospheric heat transport on Venus Implications for tectonic style and volcanism

    Science.gov (United States)

    Solomon, S. C.; Head, J. W.

    1982-01-01

    The mechanisms of plate recycling, lithospheric conduction, and hot spot volcanism are each evaluated to determine which is the dominant mode of lithospheric heat transfer on Venus, with attention given to the implications of each mechanism for the interpretation of Venus surface features. It is thought that plate recycling on Venus cannot be excluded on the basis of either theoretical arguments or present observations on topography and radar backscatter. Landforms caused by plate convergence and divergence on Venus, it is noted, would differ substantially from those on the earth owing to the high surface temperature and the absence of oceans on Venus, the lack of free or hydrated water in subducted material, the possibility that subduction would more commonly be accompanied by lithospheric delamination, and the rapid spreading rates that would be required if plate recycling removed a significant fraction of the internal heat. The possibility that the dominant mechanism early in the history of the planet was different from the one at work now is thought to merit consideration.

  11. Divergent mechanisms for the insulin resistant and hyperresponsive glucose transport in adipose cells from fasted and refed rats. Alterations in both glucose transporter number and intrinsic activity.

    OpenAIRE

    Kahn, B. B.; Simpson, I. A.; Cushman, S. W.

    1988-01-01

    The effects of fasting and refeeding on the glucose transport response to insulin in isolated rat adipose cells have been examined using 3-O-methylglucose transport in intact cells and cytochalasin B binding and Western blotting in subcellular membrane fractions. After a 72-h fast, basal glucose transport activity decreases slightly and insulin-stimulated activity decreases greater than 85%. Following 48 h of fasting, insulin-stimulated glucose transport activity is diminished from 3.9 +/- 0....

  12. Main Achievements 2003-2004 - Interdisciplinary Research - Applications of nuclear methods to biomedical physics, environmental biology, environmental physics, and medical physics - Studies of the electron and energy transport in the process of photosynthesis

    International Nuclear Information System (INIS)

    In studies of the electron and energy transport in the process of photosynthesis it has been shown that allosteric interactions within the protein matrix of photosystem II (PSII) and charge stabilizing reactions at the donor and /or acceptor side of PSII mutually influence one another. The amount of H2O molecules in the cleavage site of the oxygen evolving complex depends on the temperature. It is estimated that there are about 122 water molecules at 20oC and 62 H2O at 9-11oC. The observed 18O isotope effect during the process of oxygen evolution has been enhanced by the clustering effect. With the use of Moessbauer spectroscopy fluorescence and absorption spectroscopy, and the fast polarographic method the molecular mechanism of variable fluorescence quenching in PSII caused by copper(II) ions and tocopherolquinone has been explained and the binding sites of these compounds indicated within photosystem II

  13. Abnormal expression of dopamine and serotonin transporters associated with the pathophysiologic mechanism of Tourette syndrome

    Directory of Open Access Journals (Sweden)

    Jijun Li

    2010-01-01

    Full Text Available Background : Tourette syndrome (TS is a neurobehavioral and neuropsychiatric disorder and its pathophysiology is not well understood. However, recent studies provide evidence implicating metabolic abnormalities of dopamine (DA and serotonin (5-HT of the basal ganglia both in TS patients and TS animal models. It is also well known that dopamine and serotonin transporters (DAT and SERT are monoamine neurotransmitter transporters, which participate in the metabolism of DA and 5-HT, respectively. Objective : To evaluate whether expression of DAT and SERT in the striatum could lead to pathophysiological change in TS rat model. Materials and Methods : Twenty-four Wistar male rats were randomly allocated to: TS model group (n=12 and control group (n=12. The stereotypy counts were recorded during the 2-week period of inducing TS rat models. The levels of DA and 5-HT in striatum homogenate were measured by ELISA. The protein and mRNA expression of DAT and SERT in the striatum were tested respectively by Immunofluorescence, Western blot and quantitative real-time PCR. Results : ANOVA analysis indicated that the stereotypy scores were much higher in the TS model group than in the control group at different time points (P<0.01. By ELISA analysis, the DA concentration in striatum homogenate was higher in the TS model group (130.92 ± 25.60 ng/mL than in the control group (101.00 ± 20.14 ng/mL (P<0.01, but 5-HT concentration in striatum was found to be lower in the TS model group (59.79 ± 14.73 ng/mL compared to the control group (77.01 ± 14.05 ng/mL (P<0.05. Analysis of protein and mRNA levels revealed a lower expression of DAT, concomitant with a higher expression of SERT in striatum of the TS model group than in the control group. Conclusions : Lower expression in DAT, concomitant with higher expression in SERT could participate in the pathophysiology of TS.

  14. Main: FEA5 [TP Atlas

    Lifescience Database Archive (English)

    Full Text Available FEA5 Structural biology on efflux transport machineries to understand multi-drug resistance Effl ... ness of a drug such as an antimicrobial or an anti-cancer ... drug, is the main cause of hospital-acquired infec ... ness of a drug such as an antimicrobial or an anti-cancer ... drug, is an emerging threat worldwide. One of the ...

  15. Mechanisms of material removal and mass transport in focused ion beam nanopore formation

    Science.gov (United States)

    Das, Kallol; Freund, Jonathan B.; Johnson, Harley T.

    2015-02-01

    Despite the widespread use of focused ion beam (FIB) processing as a material removal method for applications ranging from electron microscope sample preparation to nanopore processing for DNA sequencing, the basic material removal mechanisms of FIB processing are not well understood. We present the first complete atomistic simulation of high-flux FIB using large-scale parallel molecular dynamics (MD) simulations of nanopore fabrication in freestanding thin films. We focus on the root mechanisms of material removal and rearrangement and describe the role of explosive boiling in forming nanopores. FIB nanopore fabrication is typically understood to occur via sputter erosion. This can be shown to be the case in low flux systems, where individual ion impacts are sufficiently separated in time that they may be considered as independent events. But our detailed MD simulations show that in high flux FIB processing, above a threshold level at which thermal effects become significant, the primary mechanism of material removal changes to a significantly accelerated, thermally dominated process. Under these conditions, the target is heated by the ion beam faster than heat is conducted away by the material, leading quickly to melting, and then continued heating to nearly the material critical temperature. This leads to explosive boiling of the target material with spontaneous bubble formation and coalescence. Mass is rapidly rearranged at the atomistic scale, and material removal occurs orders of magnitude faster than would occur by simple sputtering. While the phenomenology is demonstrated computationally in silicon, it can be expected to occur at lower beam fluxes in other cases where thermal conduction is suppressed due to material properties, geometry, or ambient thermal conditions.

  16. Mechanisms of material removal and mass transport in focused ion beam nanopore formation

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kallol, E-mail: das7@illinois.edu; Johnson, Harley T., E-mail: htj@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, MC-244, Urbana, Illinois 61801 (United States); Freund, Jonathan B., E-mail: jbfreund@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, MC-244, Urbana, Illinois 61801 (United States); Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, MC-236, 104 South Wright Street Urbana, Illinois 61801 (United States)

    2015-02-28

    Despite the widespread use of focused ion beam (FIB) processing as a material removal method for applications ranging from electron microscope sample preparation to nanopore processing for DNA sequencing, the basic material removal mechanisms of FIB processing are not well understood. We present the first complete atomistic simulation of high-flux FIB using large-scale parallel molecular dynamics (MD) simulations of nanopore fabrication in freestanding thin films. We focus on the root mechanisms of material removal and rearrangement and describe the role of explosive boiling in forming nanopores. FIB nanopore fabrication is typically understood to occur via sputter erosion. This can be shown to be the case in low flux systems, where individual ion impacts are sufficiently separated in time that they may be considered as independent events. But our detailed MD simulations show that in high flux FIB processing, above a threshold level at which thermal effects become significant, the primary mechanism of material removal changes to a significantly accelerated, thermally dominated process. Under these conditions, the target is heated by the ion beam faster than heat is conducted away by the material, leading quickly to melting, and then continued heating to nearly the material critical temperature. This leads to explosive boiling of the target material with spontaneous bubble formation and coalescence. Mass is rapidly rearranged at the atomistic scale, and material removal occurs orders of magnitude faster than would occur by simple sputtering. While the phenomenology is demonstrated computationally in silicon, it can be expected to occur at lower beam fluxes in other cases where thermal conduction is suppressed due to material properties, geometry, or ambient thermal conditions.

  17. Mechanisms of material removal and mass transport in focused ion beam nanopore formation

    International Nuclear Information System (INIS)

    Despite the widespread use of focused ion beam (FIB) processing as a material removal method for applications ranging from electron microscope sample preparation to nanopore processing for DNA sequencing, the basic material removal mechanisms of FIB processing are not well understood. We present the first complete atomistic simulation of high-flux FIB using large-scale parallel molecular dynamics (MD) simulations of nanopore fabrication in freestanding thin films. We focus on the root mechanisms of material removal and rearrangement and describe the role of explosive boiling in forming nanopores. FIB nanopore fabrication is typically understood to occur via sputter erosion. This can be shown to be the case in low flux systems, where individual ion impacts are sufficiently separated in time that they may be considered as independent events. But our detailed MD simulations show that in high flux FIB processing, above a threshold level at which thermal effects become significant, the primary mechanism of material removal changes to a significantly accelerated, thermally dominated process. Under these conditions, the target is heated by the ion beam faster than heat is conducted away by the material, leading quickly to melting, and then continued heating to nearly the material critical temperature. This leads to explosive boiling of the target material with spontaneous bubble formation and coalescence. Mass is rapidly rearranged at the atomistic scale, and material removal occurs orders of magnitude faster than would occur by simple sputtering. While the phenomenology is demonstrated computationally in silicon, it can be expected to occur at lower beam fluxes in other cases where thermal conduction is suppressed due to material properties, geometry, or ambient thermal conditions

  18. Mechanisms Regulating Acid-Base Transporter Expression in Breast- and Pancreatic Cancer

    DEFF Research Database (Denmark)

    Gorbatenko, Andrej

    , characteristics of which are a shift towards glycolytic metabolism and increased acid production. HER2 receptor overexpression in breast cancer leads to further increased glycolysis, invasion and metastasis, drug resistance and poor prognosis. Increased tumor glycolysis requires acquisition of mechanisms for...... receptor and p95HER2 and demonstrate that despite major similarities, a group of miRNAs are differentially regulated by full-length HER2 and p95HER2. Additionally, we demonstrate that p95HER2 downregulates a member of the c-myb family of transcription factors, MYBL1, through an oncogenic miR-221...

  19. Surface Evolution of the Sun's Magnetic Field: A Historical Review of the Flux-Transport Mechanism

    Directory of Open Access Journals (Sweden)

    Sheeley Jr. Neil R.

    2005-10-01

    Full Text Available This paper reviews our attempts to understand the transport of magnetic flux on the Sun from the Babcock and Leighton models to the recent revisions that are being used to simulate the field over many sunspot cycles. In these models, the flux originates in sunspot groups and spreads outward on the surface via supergranular diffusion; the expanding patterns become sheared by differential rotation, and the remnants are carried poleward by meridional flow. The net result of all of the flux eruptions during a sunspot cycle is to replace the initial polar fields with new fields of opposite polarity. A central issue in this process is the role of meridional flow, whose relatively low speed is near the limit of detection with Doppler techniques. A compelling feature of Leighton’s original model was that it reversed the polar fields without the need for meridional flow. Now, we think that meridional flow is central to the reversal and to the dynamo itself.

  20. A possible mechanisms for quantum coherence assisted ion transport in ion channels

    Science.gov (United States)

    Vaziri, Alipasha

    2011-03-01

    Recently it was demonstrated that long-lived quantum coherence exists during excitation energy transport in photosynthesis. It is a valid question up to which length, time and mass scales quantum coherence may extend, how to one may detect this coherence and what if any role it plays for the dynamics of the system. Ion-channels are involved in many physiological processes. In the nervous system their coordinated opening and closing generates action potentials that form the basis for intra-neural communication which are essential for information representation and processing. We have recently suggested that the selectivity filter of ion channels may exhibit quantum coherence which might be relevant for the process of ion selectivity and conduction. I will discuss some of our current experimental efforts in this direction and show that quantum resonances could provide a viable approach to probe these quantum coherences. The emergence of resonances in the conduction of ion channels that are modulated periodically by time varying external fields can serve as signatures of quantum coherence in such a system.

  1. Quantum mechanics of charged-particle beam transport through magnetic lenses

    Science.gov (United States)

    Khan, S. A.; Jagannathan, R.

    1995-03-01

    The quantum theory of charged-particle beam transport through a magnetic lens system with a straight optic axis, at the level of single-particle dynamics and disregarding spin (or, when nonzero, assuming it to be an independent spectator degree of freedom), is presented, based on the Schrödinger and Klein-Gordon equations in a form suitable for analyzing the paraxial and aberration aspects in a systematic way using a Lie algebraic approach. In the classical limit, the well known Lie algebraic treatment of the corresponding classical theory is obtained. As examples, quadrupole and axially symmetric magnetic lenses are considered. An extension of the theory to the cases of electrostatic and other electromagnetic lens systems is outlined. This work is complementary to an already known similar approach to the spinor electron optics based on the Dirac equation and provides the corresponding framework when the optics of charged particles, with or without spin, is described with scalar wave functions in the nonrelativistic and relativistic situations.

  2. Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells

    Science.gov (United States)

    Jäckle, Sara; Mattiza, Matthias; Liebhaber, Martin; Brönstrup, Gerald; Rommel, Mathias; Lips, Klaus; Christiansen, Silke

    2015-08-01

    We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and valence band edge of the polymer from ultraviolet photoelectron spectroscopy, a band diagram of the hybrid n-Si/PEDOT:PSS heterojunction is presented. The current-voltage characteristics were analyzed using Schottky and abrupt pn-junction models. The magnitude as well as the dependence of dark saturation current on n-Si doping concentration proves that the transport is governed by diffusion of minority charge carriers in the n-Si and not by thermionic emission of majorities over a Schottky barrier. This leads to a comprehensive explanation of the high observed open-circuit voltages of up to 634 mV connected to high conversion efficiency of almost 14%, even for simple planar device structures without antireflection coating or optimized contacts. The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction.

  3. Technical-evaluation report on the proposed technical-specification changes for the inservice surveillance of safety-related hydraulic and mechanical snubbers at the Maine Yankee Nuclear Power Plant (Docket No. 50-309)

    International Nuclear Information System (INIS)

    This report documents the technical evaluation of the proposed Technical Specification changes to Limiting Conditions for Operation, Surveillance Requirements and Bases for safety-related hydraulic and mechanical snubbers at the Maine Yankee Nuclear Power Plant. The evaluation is to determine whether the proposed Technical Specifications are in conformance with the model Standard Technical Specification set forth by the NRC. A check list, Appendix A of this report, compares the licensee's submittal with the NRC requirements and includes Proposed Resolution of the Deviations

  4. Mechanisms of turbulence transport in a turbine blade coolant passage with a rib turbulator

    Energy Technology Data Exchange (ETDEWEB)

    Panigrahi, P.K.; Acharya, S. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Mechanical Engineering

    1999-01-01

    This paper provides detailed measurements of the flow in a ribbed coolant passage, and attempts to delineate the important mechanisms that contribute to the production of turbulent shear stress and the normal stresses. It is shown that the separated flow behind the rib is dictated by large-scale structures, and that the dynamics of the large-scale structures, associated with sweep, ejection, and inward and outward interactions, all play an important role in the production of the turbulent shear stress. Unlike the turbulent boundary layer, in a separated shear flow past the rib, the inward and outward interaction terms are both important, accounting for a negative stress production that is nearly half of the positive stress produced by the ejection and sweep mechanisms. It is further shown that the shear layer wake persists well past the re-attachment location of the shear layer, implying that the flow between ribbed passages never recovers to that of a turbulent boundary layer. Therefore, even past re-attachment, the use of statistical turbulence models that ignore coherent structure dynamics is inappropriate.

  5. Transport mechanisms of trans-1-amino-3-fluoro[1-14C]cyclobutanecarboxylic acid in prostate cancer cells

    International Nuclear Information System (INIS)

    Introduction: We investigated the mechanisms of trans-1-amino-3-fluoro[1-14C]cyclobutanecarboxylic acid (anti-[14C]FACBC) transport by human-derived prostate cancer (PCa) cells and normal human prostatic epithelial cells (PrECs). Methods: Using PCa cells (DU145, PC-3, LNCaP) and PrECs, we performed the following in vitro experiments: time-course, kinetics, competitive inhibition by synthetic/naturally occurring amino acids (AAs), exchange transport with synthetic/naturally occurring AAs and pH-dependency of anti-[14C]FACBC uptake. We also examined the amino acid transporter (AAT) expression using flow cytometry. Results: The uptake of anti-[14C]FACBC by LNCaP and DU145 cells was higher than that by PC-3 and PrECs. The Km values for anti-[14C]FACBC were 64.4 and 191.7 μmol/L in the DU145 cells and PrECs, respectively. Total levels of anti-[14C]FACBC uptake were positively correlated with the expression level of system ASC in PCa cells. The contributions of Na+-dependent AATs to anti-[14C]FACBC uptake were greater than those of Na+-independent AATs, especially in PCa cells. In the presence of Na+, glutamine and serine showed the strongest inhibitory effect against anti-[14C]FACBC uptake, suggesting that system ASC, especially ASCT2, is an important AAT for anti-[14C]FACBC. In contrast, phenylalanine and 2-amino-bicyclo[2,2,1]heptane-2-carboxylic acid, but not N-ethylmaleimide, almost completely inhibited the anti-[14C]FACBC uptake in the absence of Na+, indicating the contribution of LAT1. In the exchange transport experiments, glutamine showed the strongest transstimulation of intracellular anti-[14C]FACBC efflux in DU145 cells. Furthermore, the contributions of Na+-independent AATs to the uptake of anti-[14C]FACBC in DU145 and PrECs were greater under acidic pH conditions than under neutral or alkaline pH conditions. Conclusions: Total uptake of anti-[14C]FACBC by PCa cells correlates with the expression level of system ASC in PCa cells. Furthermore, LAT1 is an important transport system for anti-[14C]FACBC uptake, especially in an acidic environment, such as the intra-tumoural environment.

  6. Mechanized Verification of Security Properties of Transport Layer Security 1.2 Protocol with Crypto Verif in Computational Model

    Directory of Open Access Journals (Sweden)

    Bo Meng

    2014-01-01

    Full Text Available In modern society, many transactions have been processed through web-based applications. In order to protect those critical applications against attacks, Transport Layer Security (TLS protocol has been implemented and widely deployed. The related literatures show that security analysis of TLS 1.2 protocol where cipher suite is RSA encryption has not been implemented with mechanized tool in computational model. Hence in this study, Blanchet calculus is used to analyze TLS 1.2 protocol where cipher suite is RSA encryption with mechanized tool crypto verif in computational model. The term, process and correspondence are used to model authentication in TLS 1.2 protocol where cipher suite is RSA encryption. The result shows that TLS 1.2 protocol where Cipher suite is RSA encryption has the pre master key confidentiality and authentication from server to client. The first mechanized analysis on TLS 1.2 protocol where Cipher suite is RSA encryption is implemented in computational model with active adversary in this study.

  7. Mechanism of Crystallization and Implications for Charge Transport in Poly(3-ethylhexylthiophene) Thin Films

    KAUST Repository

    Duong, Duc T.

    2014-04-09

    In this work, crystallization kinetics and aggregate growth of poly(3-ethylhexylthiophene) (P3EHT) thin films are studied as a function of film thickness. X-ray diffraction and optical absorption show that individual aggregates and crystallites grow anisotropically and mostly along only two packing directions: the alkyl stacking and the polymer chain backbone direction. Further, it is also determined that crystallization kinetics is limited by the reorganization of polymer chains and depends strongly on the film thickness and average molecular weight. Time-dependent, field-effect hole mobilities in thin films reveal a percolation threshold for both low and high molecular weight P3EHT. Structural analysis reveals that charge percolation requires bridged aggregates separated by a distance of ≈2-3 nm, which is on the order of the polymer persistence length. These results thus highlight the importance of tie molecules and inter-aggregate distance in supporting charge percolation in semiconducting polymer thin films. The study as a whole also demonstrates that P3EHT is an ideal model system for polythiophenes and should prove to be useful for future investigations into crystallization kinetics. Recrystallization kinetics and its relationship to charge transport in poly(3-ethylhexylthiophene) (P3EHT) thin films are investigated using a combination of grazing incidence X-ray diffraction, optical absorption, and field-effect transistor measurements. These results show that thin film crystallization kinetics is limited by polymer chain reorganization and that charge percolation depends strongly on the edge-to-edge distance between aggregates. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Virus in Groundwater: Characterization of transport mechanisms and impacts on an agricultural area in Uruguay

    Science.gov (United States)

    Gamazo, P. A.; Colina, R.; Victoria, M.; Alvareda, E.; Burutaran, L.; Ramos, J.; Lopez, F.; Soler, J.

    2014-12-01

    In many areas of Uruguay groundwater is the only source of water for human consumption and for industrial-agricultural economic activities. Traditionally considered as a safe source, due to the "natural filter" that occurs in porous media, groundwater is commonly used without any treatment. The Uruguayan law requires bacteriological analysis for most water uses, but virological analyses are not mentioned in the legislation. In the Salto district, where groundwater is used for human consumption and for agricultural activities, bacterial contamination has been detected in several wells but no viruses analysis have been performed. The Republic University (UDELAR), with the support of the National Agency for Research and Innovation (ANII), is studying the incidence of virus in groundwater on an intensive agriculture area of the Salto district. In this area water is pumped from the "Salto Aquifer", a free sedimentary aquifer. Below this sedimentary deposit is the "Arapey" basaltic formation, which is also exploited for water productions on its fractured zones. A screening campaign has been performed searching for bacterial and viral contamination. Total and fecal coliforms have been found on several wells and Rotavirus and Adenovirus have been detected. A subgroup of the screening wells has been selected for an annual survey. On this subgroup, besides bacteria and viruses analysis, a standard physical and chemical characterization was performed. Results show a significant seasonal variation on microbiological contamination. In addition to field studies, rotavirus circulation experiments on columns are being performed. The objective of this experiments is to determinate the parameters that control virus transport in porous media. The results of the study are expected to provide an insight into the impacts of groundwater on Salto's viral gastroenterocolitis outbreaks.

  9. Scanning internal photoemission microscopy for the identification of hot carrier transport mechanisms

    Science.gov (United States)

    Differt, D.; Pfeiffer, W.; Diesing, D.

    2012-09-01

    Linear and nonlinear internal photoemission in a thin-film metal-insulator-metal heterosystem, i.e., a Ta-TaOx-Ag junction, together with surface reflectivity are mapped with a lateral resolution of better than 5 μm. The spatial correlation of the different signals and time-resolved internal photoemission spectroscopy reveal excitation mechanisms and ballistic hot carrier injection. The internal photoemission yield variation with Ag layer thickness is quantitatively explained by above-barrier injection. The hot-spot-like behavior of the two-photon induced internal photoemission observed for short pulse excitation is attributed to local field enhancements because of Ag-film thickness reduction and plasmonic effects at structural defects.

  10. Flow pathways and nutrient transport mechanisms drive hydrochemical sensitivity to climate change across catchments with different geology and topography

    Directory of Open Access Journals (Sweden)

    J. Crossman

    2014-07-01

    Full Text Available Hydrological processes determine the transport of nutrients and passage of diffuse pollution. Consequently, catchments are likely to exhibit individual hydrochemical responses (sensitivities to climate change, which is expected to alter the timing and amount of runoff, and to impact in-stream water quality. In developing robust catchment management strategies and quantifying plausible future hydrochemical conditions it is therefore equally important to consider the potential for spatial variability in, and causal factors of, catchment sensitivity, as to explore future changes in climatic pressures. This study seeks to identify those factors which influence hydrochemical sensitivity to climate change. A perturbed physics ensemble (PPE, derived from a series of Global Climate Model (GCM variants with specific climate sensitivities was used to project future climate change and uncertainty. Using the Integrated Catchment Model of Phosphorus Dynamics (INCA-P, we quantified potential hydrochemical responses in four neighbouring catchments (with similar land use but varying topographic and geological characteristics in southern Ontario, Canada. Responses were assessed by comparing a 30 year baseline (1968–1997 to two future periods: 2020–2049 and 2060–2089. Although projected climate change and uncertainties were similar across these catchments, hydrochemical responses (sensitivity were highly varied. Sensitivity was governed by soil type (influencing flow pathways and nutrient transport mechanisms. Clay-rich catchments were most sensitive, with total phosphorus (TP being rapidly transported to rivers via overland flow. In these catchments large annual reductions in TP loads were projected. Sensitivity in the other two catchments, dominated by sandy-loams, was lower due to a larger proportion of soil matrix flow, longer soil water residence times and seasonal variability in soil-P saturation. Here smaller changes in TP loads, predominantly increases, were projected. These results suggest that the clay content of soils could be a good indicator of the sensitivity of catchments to climatic input, and reinforces calls for catchment-specific management plans.

  11. Flow pathways and nutrient transport mechanisms drive hydrochemical sensitivity to climate change across catchments with different geology and topography

    Science.gov (United States)

    Crossman, J.; Futter, M. N.; Whitehead, P. G.; Stainsby, E.; Baulch, H. M.; Jin, L.; Oni, S. K.; Wilby, R. L.; Dillon, P. J.

    2014-12-01

    Hydrological processes determine the transport of nutrients and passage of diffuse pollution. Consequently, catchments are likely to exhibit individual hydrochemical responses (sensitivities) to climate change, which are expected to alter the timing and amount of runoff, and to impact in-stream water quality. In developing robust catchment management strategies and quantifying plausible future hydrochemical conditions it is therefore equally important to consider the potential for spatial variability in, and causal factors of, catchment sensitivity, as it is to explore future changes in climatic pressures. This study seeks to identify those factors which influence hydrochemical sensitivity to climate change. A perturbed physics ensemble (PPE), derived from a series of global climate model (GCM) variants with specific climate sensitivities was used to project future climate change and uncertainty. Using the INtegrated CAtchment model of Phosphorus dynamics (INCA-P), we quantified potential hydrochemical responses in four neighbouring catchments (with similar land use but varying topographic and geological characteristics) in southern Ontario, Canada. Responses were assessed by comparing a 30 year baseline (1968-1997) to two future periods: 2020-2049 and 2060-2089. Although projected climate change and uncertainties were similar across these catchments, hydrochemical responses (sensitivities) were highly varied. Sensitivity was governed by quaternary geology (influencing flow pathways) and nutrient transport mechanisms. Clay-rich catchments were most sensitive, with total phosphorus (TP) being rapidly transported to rivers via overland flow. In these catchments large annual reductions in TP loads were projected. Sensitivity in the other two catchments, dominated by sandy loams, was lower due to a larger proportion of soil matrix flow, longer soil water residence times and seasonal variability in soil-P saturation. Here smaller changes in TP loads, predominantly increases, were projected. These results suggest that the clay content of soils could be a good indicator of the sensitivity of catchments to climatic input, and reinforces calls for catchment-specific management plans.

  12. Hydro-mechanical and gas transport properties of bentonite blocks - role of interfaces

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. The long-term safety of the disposal of nuclear waste is an important issue in all countries with a significant nuclear programme. Repositories for the disposal of high-level and long-lived radioactive waste generally rely on a multi-barrier system to isolate the waste from the biosphere. The multi-barrier system typically comprises the natural geological barrier provided by the repository host rock and its surroundings and an engineered barrier system (EBS), i.e. the backfilling and sealing of shafts and galleries to block any preferential path for radioactive contaminants. Because gas will be created in a radioactive waste repository performance assessment requires quantification of the relevancy of various potential pathways. Referring to the sealing plugs it is expected that in addition to the matrix properties of the sealing material conductive discrete interfaces inside the sealing elements itself and to the host rock may act not only as mechanical weakness planes but also as preferential gas pathways (Popp, 2009). For instance despite the assumed self sealing capacity of bentonite inherent existing interfaces may be reopened during gas injection. Our lab investigations are aiming on a comprehensive hydro-mechanical characterization of interfaces in bentonite buffers, i.e. (1) between prefabricated bentonite blocks itself and (2) on mechanical contacts of bentonite blocks and concrete to various host rocks, i.e. granite. We used as reference material pre-compacted bentonite blocks consisting of a sand clay-bentonite mixture but the variety of bentonite-based buffer materials has to be taken in mind. The blocks were manufactured in the frame work of the so-called dam - project 'Sondershausen', i.e. a German research project performed between 1997 and 2002. The blocks have a standard size of (250 x 125 x 62.5) mm. Approximately 500 t of such bentonite blocks have been produced and assembled in underground drift sealing elements. The investigations consist of: - long-term water injection tests in a new designed oedometer cell with different sample constellations under well controlled stress and swelling conditions to provide data about - time dependent interface 'permeability' changes during long-term compaction and fluid injection - gas entry pressures and relative gas permeability changes during pressure dependent gas injection; - shear tests to quantify mechanical interface properties of pre-saturated bentonite blocks under well controlled shear forces or displacements. As initial characterization both, triaxial and direct strength tests were performed, which allow to separate between matrix and interface properties. The investigations are being performed in the framework of the pan-European project FORGE project which aims on the generation and movement of repository gases. Results and interpretation The performed lab investigations cover a wide field of hydro-mechanical properties of bentonite blocks, which represent a favorable option for constructing sealing plugs in different host rock environments. Based on the experimental results the following conclusions can be drawn: - At dry conditions gas flow along interfaces is at least 4 orders higher than through the matrix. Increase of confinement significantly lowers the gas flow but the effect is more pronounced for interfaces → crack sealing. - Saturation of bentonite block assembly, i.e. blocks with a common interface, is not affected by the interfaces and only weakly by the acting confining pressure. - During gas injection a significant effect is only observed if the minimal stress is passed resulting in some minor gas flow. - The gas break through results in stationary inflow but no significant effect on the total stress is measured, probably due to the central gas injection. - The measured gas threshold pressures under constant volume conditions significantly exceed the sum of the swelling pressure and externally-applied pore water pressure - drained conditions. An important observation is that despite the former interface the bentonite block assembly behaves during the saturation of the buffer not different than the homogenous matrix. This has been confirmed as well by gas injection tests on the former interface as well by shear tests. The demonstration of the development of cohesion after pre-saturation is a favorable finding, because this verifies physical healing of the interface. In addition, cohesion inside the matrix helps to explain why the measured gas entry pressures are higher than the applied minimal stress

  13. Effect of chlordecone (kepone) on calcium transport mechanisms in rat heart sarcoplasmic reticulum

    International Nuclear Information System (INIS)

    Since chlordecone (Kepone, CD) interferes with cardiac Na+ ion translocases, we have studied CD effects on cardiac SR calcium pump activity. SR was isolated from heart ventricles of male Sprague-Dawley rats. Cardiac SR Ca2+-ATPase, 45Ca-uptake and cAMP as well as calmodulin (CaM) dependent protein phosphorylation were measured. Ca2+-ATPase was differentiated into low affinity and high affinity forms by measuring the activity using 50 and 0.7 ?M free Ca2+ respectively. CD in vitro inhibited 45Ca-uptake by SR in a concentration dependent manner with an IC50 value of 7 ?M and SR 45Ca-uptake was totally inhibited at 20-30 ?M CD. In agreement with this, both high affinity and low affinity Ca2+-ATPases, which are involved in Ca2+ transport across membranes, were also inhibited by CD in a concentration dependent manner with IC50 values of 0.7 and 3.2 ?M respectively. Both Ca2+-ATPase and 45Ca-uptake by cardiac SR were significantly lower in rats treated with CD (25, 50 or 75 mg/kg) when compared to control rats. cAMP as well as CaM significantly elevated the 32P-binding to SR proteins in vitro to about 70-80%. In the presence of CD, this 32P-binding was reduced, however, not concentration dependent. In agreement with in vitro studies, 32P-bound to proteins was significantly lowered in rats treated with CD. SDS-polyacrylamide gel electrophoresis of the cardiac SR revealed the presence of at least 30 comassie blue-stainable bands with mobilities corresponding to molecular weights ranging from 9 to 120 kDa using 15% acrylamide gels. Autoradiographs from samples incubated in the presence of cAMP or CaM indicated 32P-incorporation in 7 bands. Of these, bands corresponding to about 24 kDa and adjacent lower molecular weights decreased in their intensity by CD in vitro as well as in vivo. (LN)

  14. Effect of chlordecone (kepone) on calcium transport mechanisms in rat heart sarcoplasmic reticulum

    Energy Technology Data Exchange (ETDEWEB)

    Kodavanti, P.R.S.; Yallapragada, P.R.; Desaiah, D. (Department of Neurology, University of Mississippi Medical Center, Jackson (USA)); Cameron, J.A. (Department of Biology, Jackson State University, Jackson (USA))

    1990-01-01

    Since chlordecone (Kepone, CD) interferes with cardiac Na{sup +} ion translocases, we have studied CD effects on cardiac SR calcium pump activity. SR was isolated from heart ventricles of male Sprague-Dawley rats. Cardiac SR Ca{sup 2+}-ATPase, {sup 45}Ca-uptake and cAMP as well as calmodulin (CaM) dependent protein phosphorylation were measured. Ca{sup 2+}-ATPase was differentiated into low affinity and high affinity forms by measuring the activity using 50 and 0.7 {mu}M free Ca{sup 2+} respectively. CD in vitro inhibited {sup 45}Ca-uptake by SR in a concentration dependent manner with an IC50 value of 7 {mu}M and SR {sup 45}Ca-uptake was totally inhibited at 20-30 {mu}M CD. In agreement with this, both high affinity and low affinity Ca{sup 2+}-ATPases, which are involved in Ca{sup 2+} transport across membranes, were also inhibited by CD in a concentration dependent manner with IC50 values of 0.7 and 3.2 {mu}M respectively. Both Ca{sup 2+}-ATPase and {sup 45}Ca-uptake by cardiac SR were significantly lower in rats treated with CD (25, 50 or 75 mg/kg) when compared to control rats. cAMP as well as CaM significantly elevated the {sup 32}P-binding to SR proteins in vitro to about 70-80%. In the presence of CD, this {sup 32}P-binding was reduced, however, not concentration dependent. In agreement with in vitro studies, {sup 32}P-bound to proteins was significantly lowered in rats treated with CD. SDS-polyacrylamide gel electrophoresis of the cardiac SR revealed the presence of at least 30 comassie blue-stainable bands with mobilities corresponding to molecular weights ranging from 9 to 120 kDa using 15% acrylamide gels. Autoradiographs from samples incubated in the presence of cAMP or CaM indicated {sup 32}P-incorporation in 7 bands. Of these, bands corresponding to about 24 kDa and adjacent lower molecular weights decreased in their intensity by CD in vitro as well as in vivo. (LN).

  15. Molire theory of multiple Coulomb scattering with ionization and the transport mechanism of the multiple scattering process.

    Science.gov (United States)

    Nakatsuka, Takao; Nishimura, Jun

    2008-08-01

    The Molire theory of multiple Coulomb scattering is improved to take account of ionization loss by applying a differential formulation of the theory. Distributions for the deflection angle theta over, as well as for any linear combination between theta over and the lateral displacement r over, under the ionization process are derived by a series expansion with the same universal functions f(n)(theta) of Molire, except that the values for both the expansion parameter B and the scale angle thetaM are corrected from those under the fixed-energy process. We find that Goudsmit-Saunderson angular distribution with ionization is also expressed by the same characteristic parameters B and thetaM derived above by the Molire theory. The transport mechanism of Molire process of multiple Coulomb scattering and the stochastic property of Molire series expansion are also investigated and discussed. PMID:18850815

  16. Mechanical and charge transport properties of alkanethiol self-assembled monolayers on Au (111) surface: The Role of Molecular Tilt

    Energy Technology Data Exchange (ETDEWEB)

    Mulleregan, Alice; Qi, Yabing; Ratera, Imma; Park, Jeong Y.; Ashby, Paul D.; Quek, Su Ying; Neaton, J. B.; Salmeron, Miquel

    2007-11-12

    The relationship between charge transport and mechanical properties of alkanethiol self-assembled monolayers (SAM) on Au(111) films has been investigated using an atomic force microscope with a conductive tip. Molecular tilts induced by the pressure applied by the tip cause stepwise increases in film conductivity. A decay constant {beta} = 0.57 {+-} 0.03 {angstrom}{sup -1} was found for the current passing through the film as a function of tip-substrate separation due to this molecular tilt. This is significantly smaller than the value of {approx} 1 {angstrom}{sup -1} found when the separation is changed by changing the length of the alkanethiol molecules. Calculations indicate that for isolated dithiol molecules S-bonded to hollow sites, the junction conductance does not vary significantly as a function of molecular tilt. The impact of S-Au bonding on SAM conductance is discussed.

  17. Macro-scale complexity of nano- to micro-scale architecture of olivine crystals through an iodine vapour transport mechanism

    Indian Academy of Sciences (India)

    Raymond L D Whitby; Takahiro Fukuda; Toru Maekawa

    2014-04-01

    The production of nano- to micro-scale olivine (magnesium and iron silicate) crystals has been achieved at relatively low temperatures through an iodine vapour transport of the metal onto amorphous silicon dioxide. The process occurs down a temperature gradient from 800 to 600°C yielding high quality crystals with long range crystallinity, highly complex interconnectivity and intricate macroscale architecture. Scanning electron microscopy (SEM) imaging of the substrate before and after the reaction reveals that the amorphous silicon oxide species is mobile, due to the lack of correlation between the silicon oxide layer and the final olivine particles, leading to a vapour–liquid–solid or vapour–solid growth mechanism. This technique demonstrates a facile, low temperature synthetic route towards olivine crystals with nano- to micro-scale dimensions.

  18. Proton Gradients as a Key Physical Factor in the Evolution of the Forced Transport Mechanism Across the Lipid Membrane

    Science.gov (United States)

    Strbak, Oliver; Kanuchova, Zuzana; Krafcik, Andrej

    2016-04-01

    A critical phase in the transition from prebiotic chemistry to biological evolution was apparently an asymmetric ion flow across the lipid membrane. Due to imbalance in the ion flow, the early lipid vesicles could selectively take the necessary molecules from the environment, and release the side-products from the vesicle. Natural proton gradients played a definitively crucial role in this process, since they remain the basis of energy transfer in the present-day cells. On the basis of this supposition, and the premise of the early vesicle membrane's impermeability to protons, we have shown that the emergence of the proton gradient in the lipid vesicle could be a key physical factor in the evolution of the forced transport mechanism (pore formation and active transport) across the lipid bilayer. This driven flow of protons across the membrane is the result of the electrochemical proton gradient and osmotic pressures on the integrity of the lipid vesicle. At a critical number of new lipid molecules incorporated into the vesicle, the energies associated with the creation of the proton gradient exceed the bending stiffness of the lipid membrane, and overlap the free energy of the lipid bilayer pore formation.

  19. An Investigation of Neutrino-Driven Convection and the Core Collapse Supernova Mechanism Using Multigroup Neutrino Transport

    CERN Document Server

    Mezzacappa, A; Bruenn, S W; Blondin, J M; Guidry, M W; Strayer, M R; Umar, A S

    1996-01-01

    We investigate neutrino-driven convection in core collapse supernovae and its ramifications for the explosion mechanism. We begin with an ``optimistic'' 15 solar mass precollapse model, which is representative of the class of stars with compact iron cores. This model is evolved through core collapse and bounce in one dimension using multigroup (neutrino-energy--dependent) flux-limited diffusion (MGFLD) neutrino transport and Lagrangian hydrodynamics, providing realistic initial conditions for the postbounce convection and evolution. Our two-dimensional simulation begins at 106 ms after bounce at a time when there is a well-developed gain region, and proceeds for 400 ms. We couple two-dimensional (PPM) hydrodynamics to one-dimensional MGFLD neutrino transport. At 225 ms after bounce we see large-scale convection behind the shock, characterized by high-entropy, mushroom-like, expanding upflows and dense, low-entropy, finger-like downflows. The upflows reach the shock and distort it from sphericity. The radial c...

  20. Exploring the pH-dependent substrate transport mechanism of FocA using molecular dynamics simulation.

    Science.gov (United States)

    Lv, Xiaoying; Liu, Huihui; Ke, Meng; Gong, Haipeng

    2013-12-17

    FocA belongs to the formate-nitrate transporter family and plays an essential role in the export and uptake of formate in organisms. According to the available crystal structures, the N-terminal residues of FocA are structurally featureless at physiological conditions but at reduced pH form helices to harbor the cytoplasmic entrance of the substrate permeation pathway, which apparently explains the cessation of electrical signal observed in electrophysiological experiments. In this work, we found by structural analysis and molecular dynamics simulations that those N-terminal helices cannot effectively preclude the substrate permeation. Equilibrium simulations and thermodynamic calculations suggest that FocA is permeable to both formate and formic acid, the latter of which is transparent to electrophysiological studies as an electrically neutral species. Hence, the cease of electrical current at acidic pH may be caused by the change of the transported substrate from formate to formic acid. In addition, the mechanism of formate export at physiological pH is discussed. PMID:24359743

  1. Transport and aggregation of Al2O3 nanoparticles through saturated limestone under high ionic strength conditions: measurements and mechanisms

    International Nuclear Information System (INIS)

    Aluminum oxide (Al2O3) nanoparticles (NPs) are being utilized in a broad range of applications; thus, noticeable quantities of these particles are being released into the environment. Issues of how and where these particles distribute into the subsurface remain major challenges. In this study, mechanisms governing the transport and aggregation of Al2O3-NPs (Alpha-40 nm) through saturated limestone porous media under different ionic strength conditions were evaluated. For this aim, 50 mg of Al2O3-NPs was dispersed in 1 L of different electrolyte solutions including NaCl and CaCl2. Ionic strength range was selected from deionized water up to 500 mM. Breakthrough curves in the column effluent were measured by UV–VIS spectrometry. It was found that the presence of NaCl and CaCl2 in the suspensions led to formation of ion bridges among NPs. Thus, the stability of Al2O3-NPs significantly declined and NPs started to flocculate and form bigger clusters. Furthermore, ionic strength caused considerable delay in NPs breakthrough in the effluents and reduction of NPs recovery. CaCl2 compared to NaCl was found more effective in instability and deposition of Al2O3-NPs. In addition, the obtained results from transport experiments were checked against classical filtration and Derjaguin–Landau–Verwey–Overbeek (DLVO) theories. The results were found to be in agreement with named theories

  2. Mechanisms of calcium transport in small intestine. Overall review of the contract, September 1, 1972--March 1, 1975

    International Nuclear Information System (INIS)

    During the past three years considerable advance has been registered in our understanding of the mechanism of intestinal calcium transport, which is activated in response to 1,25-(OH)2D3, the active form of the vitamin in the system. In brush borders isolated from vitamin D-deficient chicks, a 200,000 molecular weight protein has been found by disc gel electrophoresis which is not present in chicks given vitamin D. This protein does not bind calcium and does not possess calcium dependent adenosine triphosphatase activity. Following the administration of 1,25-(OH)2D3 to the deficient chicks this protein disappears from the disc gel profiles and a protein of molecular weight 220,000 appears in the gel profiles. This protein has been isolated and shown to possess calcium adenosine triphosphatase activity, alkaline phosphatase activity and it binds calcium. Work is progressing on the purification of these proteins with the ultimate aim of discerning what role they have in intestinal calcium transport. (U.S.)

  3. Endocytosis of ABCG2 drug transporter caused by binding of 5D3 antibody: trafficking mechanisms and intracellular fate.

    Science.gov (United States)

    Studzian, Maciej; Bartosz, Grzegorz; Pulaski, Lukasz

    2015-08-01

    ABCG2, a metabolite and xenobiotic transporter located at the plasma membrane (predominantly in barrier tissues and progenitor cells), undergoes a direct progressive endocytosis process from plasma membrane to intracellular compartments upon binding of 5D3 monoclonal antibody. This antibody is specific to an external epitope on the protein molecule and locks it in a discrete conformation within its activity cycle, presumably providing a structural trigger for the observed internalization phenomenon. Using routine and novel assays, we show that ABCG2 is endocytosed by a mixed mechanism: partially via a rapid, clathrin-dependent pathway and partially in a cholesterol-dependent, caveolin-independent manner. While the internalization process is entirely dynamin-dependent and converges initially at the early endosome, subsequent intracellular fate of ABCG2 is again twofold: endocytosis leads to only partial lysosomal degradation, while a significant fraction of the protein is retained in a post-endosomal compartment with the possibility of at least partial recycling back to the cell surface. This externally triggered, conformation-related trafficking pathway may serve as a general regulatory paradigm for membrane transporters, and its discovery was made possible thanks to consistent application of quantitative methods. PMID:25918011

  4. Ab initio study of the mechanical and transport properties of pure and contaminated silver nanowires

    International Nuclear Information System (INIS)

    The mechanical properties and conductance of contaminated and pure silver nanowires were studied using density functional theory (DFT) calculations. Several nanowires containing O2 on their surfaces were elongated along two different directions. All of the NWs thinned down to single atom chains. In most simulations, the breaking force was not affected by the presence of the O2, and similar fracture strengths of ≈1 nN were computed for the pure and impure NWs. When the O2 became incorporated in the single atom chain, the fracture occurred at the Ag–O bond and a lower fracture strength was found. All of the simulations showed that the impurity interacted with the silver atoms to reduce the electron density in its nearby vicinity. A variety of conductance effects were observed depending on the location of the impurity. When the impurity migrated during the elongation to the thinnest part of the NW, it reduced the conductance significantly, and an ≈1 G0 conductance (usually associated with a single atom chain) was calculated for three- and two-dimensional structures. When the impurity was adjacent to the single atom chain, the conductance reduced almost to zero. However, when it stayed far from the thinnest part of the NW, the impurity had only a small influence on the conductance. (paper)

  5. Fluorination of an antiepileptic drug: A self supporting transporter by oxygen enrichment mechanism.

    Science.gov (United States)

    Natchimuthu, V; Amoros, J; Ravi, S

    2016-03-01

    Drug therapy of seizures involves producing high levels of antiepileptic drugs in the blood. Drug must enter the brain by crossing from the blood into the brain tissue, called a transvascular route (TVR). Even before the drug can reach the brain tissue, factors such as systemic toxicity, macrophage phagocytises and reduction in oxygen content limit the success of this TVR. Encapsulating the drug within a nano scale delivering system, synthesising drugs with low molecular weight are the best mechanisms to deliver the drug to the brain. But through this article, we have explored a possibility of attaching a molecule 4-(trifluoromethyl) benzoic acid (TFMBA), that possess more number of fluorine atom, to benzodiazepine (BDZ) resulting in an ionic salt (S)-(+)-2,3-dihydro-1H-pyrrolo[2,1-c][1,4]benzodiazepine5,11(10H,11aH)-dione with 4-(trifluoromethyl)benzoic acid. By this way, reducing the toxicity of BDZ than the conventional anti-epileptic drugs (AEDs), increasing the solubility, reducing the melting point, enriching the TVR with excess oxygen content with the support of fluorine. With all these important prerequisites fulfilled, the drug along with the attached molecule is expected to travel more comfortably through the TVR without any external support than any other conventional AEDs. FTIR, (1)H NMR, (13)C NMR, HRMS spectroscopy, HRTEM and In vitro cytotoxicity analysis supports this study. PMID:26708322

  6. Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

    Science.gov (United States)

    Philipp, Sonja; Afşar, Filiz; Gudmundsson, Agust

    2013-12-01

    Fractures generated by internal fluid pressure, for example, dykes, mineral veins, many joints and man-made hydraulic fractures, are referred to as hydrofractures. Together with shear fractures, they contribute significantly to the permeability of fluid reservoirs such as those of petroleum, geothermal water, and groundwater. Analytical and numerical models show that - in homogeneous host rocks - any significant overpressure in hydrofractures theoretically generates very high crack tip tensile stresses. Consequently, overpressured hydrofractures should propagate and help to form interconnected fracture systems that would then contribute to the permeability of fluid reservoirs. Field observations, however, show that in heterogeneous and anisotropic, e.g., layered, rocks many hydrofractures become arrested or offset at layer contacts and do not form vertically interconnected networks. The most important factors that contribute to hydrofracture arrest are discontinuities (including contacts), stiffness changes between layers, and stress barriers, where the local stress field is unfavourable to hydrofracture propagation. A necessary condition for a hydrofracture to propagate to the surface is that the stress field along its potential path is everywhere favourable to extension-fracture formation so that the probability of hydrofracture arrest is minimised. Mechanical layering and the resulting heterogeneous stress field largely control whether evolving hydrofractures become confined to single layers (stratabound fractures) or not (non-stratabound fractures) and, therefore, if a vertically interconnected fracture system forms. Non-stratabound hydrofractures may propagate through many layers and generate interconnected fracture systems. Such systems commonly reach the percolation threshold and largely control the overall permeability of the fluid reservoirs within which they develop.

  7. Effect of triorganotin compounds on calcium transport mechanisms in rat cardiac sarcoplasmic reticulum

    International Nuclear Information System (INIS)

    Although organotin compounds, in general, are neurotoxicants, recent studies indicate that these tin compounds affect heme metabolism as well as cardiovascular system. Sarcoplasmic reticulum (SR) calcium pump together with phosphorylation of phospholamban has an important role in myocardial contraction and relaxation. Since organotin compounds interfere with cardiovascular system, we have studied the in vitro as well as in vivo effects of tributyltin bromide (TBT), triethyltin bromide (TET) and trimethyltin chloride (TMT) on cardiac SR Ca2+-pump activity, in order to know the relative potency of these tin compounds. SR was isolated from heart ventricles of male Sprague-Dawley rats and used for in vitro studies. For in vivo studies, rats were treated orally in corn oil for 6 days with different doses of TET (0.5, 1.0 and 1.5 mg/kg/d), TMT (0.75, 1.5 and 2.5 mg/kg/d) and TBT (0.75, 1.5 and 2.5 mg/kg/d). Rats were sacrificed 24 hr after the last dosage and cardiac SR was prepared. Cardiac SR Ca2+-ATPase and 45Ca-uptake were measured. All the three tin compounds inhibited Ca2+-ATPase and 45Ca-uptake in vitro in a concentration dependent manner. The order of potency for Ca2+-ATPase as determined IC50, is TBT (2 uM) > TET (63 uM) > TMT (280 uM). For 45Ca-uptake, if followed the same order i.e., TBT (0.35 uM) > TET (10 uM) > TMT (440 uM). In agreement with in vitro results, both SR Ca2+-ATPase and 45Ca-uptake were significantly inhibited in rats treated with these tin compounds. These studies indicate that triorganotin compounds affect Ca2+-pumping mechanisms and thereby alter cardiac contraction-relaxation process

  8. Thermo-Hydro-Mechanical Evolution of Transport Properties in Porous Media: From Laboratory to the Gro-Schnebeck Geothermal Reservoir.

    Science.gov (United States)

    Jacquey, Antoine; Cacace, Mauro; Blcher, Guido; Watanabe, Norihiro; Scheck-Wenderoth, Magadalena

    2015-04-01

    Quantifying variations of transport properties of porous material, which are porosity and permeability is of special interest for geothermal applications. Variations of these properties result from the coupling between rock deformation and thermal processes. Significant pore pressure and temperature changes can occur during injection and production of fluid. Such changes have a direct impact on the stress-field affecting the geothermal reservoir performance. Understanding the coupling between deformation of the porous material and variation of its properties for mass and energy transfer is therefore a major focus for any geothermal operations. Deformation of a porous material filled with fluid is based on variations of bulk and pore volumes and affects therefore the basic transport properties of the rock. Variations of the transport properties can be expressed by theoretical formulations based on experimental observations and then integrated into numerical models which can be used to predict reservoir performance at the field scale. The aim of this study is to develop a complete poro- and thermoelastic formulation capable of explaining and quantifying fluid-rock interactions in a context of geothermal applications. In a first step, formulations to quantify porosity variations are tested with the open-source finite element method based software OpenGeoSys (Kolditz et al. 2012) and compared to laboratory experiments to constrain the parameters involved. Numerical description of the physical phenomena involved for such behavior requires to account for the coupling between deformation, thermal and hydraulic processes and the relations between different scales. Three different formulations with H-M coupling are studied which are based on the theories of poroelasticity and crack closure (Zimmerman 1991, Blcher et al. 2013 and Chin et al. 2000). These three formulations are tested on two different kinds of sandstones (Flechtinger and Bentheimer sandstones) by comparing simulations to experimental results. It is then possible to constrain some parameters involved in these porosity formulations. One formulation with T-M coupling is also investigated (Ghabezloo et al. 2008) which is based on thermoelasticity and a fluid volume balance. Then, this theoretical background has been applied to the field scale to study the performance of the Gro-Schnebeck geothermal reservoir situated in the North-East German Basin. Current results on numerical simulations of Thermo-Hydro-Mechanical coupled processes involving transport properties evolution will be presented.

  9. Impact of defects on the electrical transport, optical properties and failure mechanisms of GaN nanowires.

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Andrew M.; Aubry, Sylvie; Shaner, Eric Arthur; Siegal, Michael P.; Li, Qiming; Jones, Reese E.; Westover, Tyler; Wang, George T.; Zhou, Xiao Wang; Talin, Albert Alec; Bogart, Katherine Huderle Andersen; Harris, C. Thomas; Huang, Jian Yu

    2010-09-01

    We present the results of a three year LDRD project that focused on understanding the impact of defects on the electrical, optical and thermal properties of GaN-based nanowires (NWs). We describe the development and application of a host of experimental techniques to quantify and understand the physics of defects and thermal transport in GaN NWs. We also present the development of analytical models and computational studies of thermal conductivity in GaN NWs. Finally, we present an atomistic model for GaN NW electrical breakdown supported with experimental evidence. GaN-based nanowires are attractive for applications requiring compact, high-current density devices such as ultraviolet laser arrays. Understanding GaN nanowire failure at high-current density is crucial to developing nanowire (NW) devices. Nanowire device failure is likely more complex than thin film due to the prominence of surface effects and enhanced interaction among point defects. Understanding the impact of surfaces and point defects on nanowire thermal and electrical transport is the first step toward rational control and mitigation of device failure mechanisms. However, investigating defects in GaN NWs is extremely challenging because conventional defect spectroscopy techniques are unsuitable for wide-bandgap nanostructures. To understand NW breakdown, the influence of pre-existing and emergent defects during high current stress on NW properties will be investigated. Acute sensitivity of NW thermal conductivity to point-defect density is expected due to the lack of threading dislocation (TD) gettering sites, and enhanced phonon-surface scattering further inhibits thermal transport. Excess defect creation during Joule heating could further degrade thermal conductivity, producing a viscous cycle culminating in catastrophic breakdown. To investigate these issues, a unique combination of electron microscopy, scanning luminescence and photoconductivity implemented at the nanoscale will be used in concert with sophisticated molecular-dynamics calculations of surface and defect-mediated NW thermal transport. This proposal seeks to elucidate long standing material science questions for GaN while addressing issues critical to realizing reliable GaN NW devices.

  10. Revealing the Molecular Structure and the Transport Mechanism at the Base of Primary Cilia Using Superresolution STED Microscopy

    Science.gov (United States)

    Yang, Tung-Lin

    The primary cilium is an organelle that serves as a signaling center of the cell and is involved in the hedgehog signaling, cAMP pathway, Wnt pathways, etc. Ciliary function relies on the transportation of molecules between the primary cilium and the cell, which is facilitated by intraflagellar transport (IFT). IFT88, one of the important IFT proteins in complex B, is known to play a role in the formation and maintenance of cilia in various types of organisms. The ciliary transition zone (TZ), which is part of the gating apparatus at the ciliary base, is home to a large number of ciliopathy molecules. Recent studies have identified important regulating elements for TZ gating in cilia. However, the architecture of the TZ region and its arrangement relative to intraflagellar transport (IFT) proteins remain largely unknown, hindering the mechanistic understanding of the regulation processes. One of the major challenges comes from the tiny volume at the ciliary base packed with numerous proteins, with the diameter of the TZ close to the diffraction limit of conventional microscopes. Using a series of stimulated emission depletion (STED) superresolution images mapped to electron microscopy images, we analyzed the structural organization of the ciliary base. Subdiffraction imaging of TZ components defines novel geometric distributions of RPGRIP1L, MKS1, CEP290, TCTN2 and TMEM67, shedding light on their roles in TZ structure, assembly, and function. We found TCTN2 at the outmost periphery of the TZ close to the ciliary membrane, with a 227+/-18 nm diameter. TMEM67 was adjacent to TCTN2, with a 205+/-20 nm diameter. RPGRIP1L was localized toward the axoneme at the same axial level as TCTN2 and TMEM67, with a 165+/-8 nm diameter. MKS1 was situated between TMEM67 and RPGRIP1L, with an 186+/-21 nm diameter. Surprisingly, CEP290 was localized at the proximal side of the TZ close to the distal end of the centrin-labeled basal body. The lateral width was unexpectedly close to the width of the basal body, distant from the potential Y-links region of the TZ. Moreover, IFT88 was intriguingly distributed in two distinct patterns, forming three puncta or a Y shape at the ciliary base found in human retinal pigment epithelial cells (RPE), human fibroblasts (HFF), mouse inner medullary collecting duct (IMCD) cells and mouse embryonic fibroblasts (MEFs). We hypothesize that the two distribution states of IFT88 correspond to the open and closed gating states of the TZ, where IFT particles aggregate to form three puncta when the gate is closed, and move to form the branches of the Y-shape pattern when the gate is open. Two reservoirs of IFT particles, correlating with phases of ciliary growth, were localized relative to the internal structure of the TZ. These subdiffraction images reveal unprecedented architectural details of the TZ, providing a basic structural framework for future functional studies. To visualize the dynamic movement of IFT particles within primary cilia, we further conducted superresolution live-cell imaging of IFT88 fused to EYFP in IMCD cells. Our findings, in particular, show IFT88 particles pass through the TZ at a reduced speed by approximately 50%, implying the gating mechanism is involved at this region to slow down IFT trafficking. Finally, we report the distinct transport pathways of IFT88 and Smo (Smoothened), an essential player to hedgehog signaling, to support our hypothesis that two proteins are transported in different mechanisms at the ciliary base, based on dual-color superresolution imaging.

  11. Study on the bubble transport mechanism in an acoustic standing wave field.

    Science.gov (United States)

    Xi, Xiaoyu; Cegla, Frederic B; Lowe, Michael; Thiemann, Andrea; Nowak, Till; Mettin, Robert; Holsteyns, Frank; Lippert, Alexander

    2011-12-01

    The use of bubbles in applications such as surface chemistry, drug delivery, and ultrasonic cleaning etc. has been enormously popular in the past two decades. It has been recognized that acoustically-driven bubbles can be used to disturb the flow field near a boundary in order to accelerate physical or chemical reactions on the surface. The interactions between bubbles and a surface have been studied experimentally and analytically. However, most of the investigations focused on violently oscillating bubbles (also known as cavitation bubble), less attention has been given to understand the interactions between moderately oscillating bubbles and a boundary. Moreover, cavitation bubbles were normally generated in situ by a high intensity laser beam, little experimental work has been carried out to study the translational trajectory of a moderately oscillating bubble in an acoustic field and subsequent interactions with the surface. This paper describes the design of an ultrasonic test cell and explores the mechanism of bubble manipulation within the test cell. The test cell consists of a transducer, a liquid medium and a glass backing plate. The acoustic field within the multi-layered stack was designed in such a way that it was effectively one dimensional. This was then successfully simulated by a one dimensional network model. The model can accurately predict the impedance of the test cell as well as the mode shape (distribution of particle velocity and stress/pressure field) within the whole assembly. The mode shape of the stack was designed so that bubbles can be pushed from their injection point onto a backing glass plate. Bubble radial oscillation was simulated by a modified Keller-Miksis equation and bubble translational motion was derived from an equation obtained by applying Newton's second law to a bubble in a liquid medium. Results indicated that the bubble trajectory depends on the acoustic pressure amplitude and initial bubble size: an increase of pressure amplitude or a decrease of bubble size forces bubbles larger than their resonant size to arrive at the target plate at lower heights, while the trajectories of smaller bubbles are less influenced by these factors. The test cell is also suitable for testing the effects of drag force on the bubble motion and for studying the bubble behavior near a surface. PMID:21719064

  12. Arsenic hypertolerance in the protist Euglena mutabilis is mediated by specific transporters and functional integrity maintenance mechanisms.

    Science.gov (United States)

    Halter, David; Andres, Jrmy; Plewniak, Frdric; Poulain, Julie; Da Silva, Corinne; Arsne-Ploetze, Florence; Bertin, Philippe N

    2015-06-01

    Arsenic is a toxic metalloid known to cause multiple and severe cellular damages, including lipid peroxidation, protein misfolding, mutagenesis and double and single-stranded DNA breaks. Thus, exposure to this compound is lethal for most organisms but some species such as the photosynthetic protist Euglena mutabilis are able to cope with very high concentrations of this metalloid. Our comparative transcriptomic approaches performed on both an arsenic hypertolerant protist, i.e. E.?mutabilis, and a more sensitive one, i.e. E.?gracilis, revealed multiple mechanisms involved in arsenic tolerance. Indeed, E.?mutabilis prevents efficiently the accumulation of arsenic in the cell through the expression of several transporters. More surprisingly, this protist induced the expression of active DNA reparation and protein turnover mechanisms, which allow E.?mutabilis to maintain functional integrity of the cell under challenging conditions. Our observations suggest that this protist has acquired specific functions regarding arsenic and has developed an original metabolism to cope with acid mine drainages-related stresses. PMID:24698441

  13. Theoretical study on mechanical and electron-transport properties of conjugated molecular junctions with carboxylic or methyl sulfide links

    International Nuclear Information System (INIS)

    The mechanical and electronic transport properties of 4-(methylthio)benzoic acid (M1), 1,4-bis(methylthio) benzene (M2) and methyl 4-(methylthio)benzoate (M3) molecular junctions are studied employing density functional theory and elastic scattering Green's function method. The numerical results show that the rupture force of M1 and M2 junctions are both about 0.60.1nN as experiment probed, which is much smaller than the force to break COO?Au bond. The COO? group strongly influenced on M1 molecular junction and further strengthened SMeAu bond at the other end of the junction. The M3 junction is less stable because the CH3 group linked to COO group destroyed the mechanical stability of COOAu connection. The conductance of M2 junction is about an order larger than that of M1 junction as the experiment probed. The less stable feature of M3 junction leads the absence of conductive peak.

  14. Analysis and development of fracture mechanical failure concepts on the basis of research results from the field of component safety engineering. Points of main interest: J-integral concept, crack resistance curves, dynamic parameters

    International Nuclear Information System (INIS)

    On the basis of results and data obtained within the framework of reactor safety research, activities for the development and application of fracture mechanical failure concepts for assessing the behaviour of structural members and components have been carried out in the years 1980 through 1985 in close co-operation with the FhIWM at Freiburg, the IEHK of Aachen University, and the BAM, Berlin. The work performed by the FhIWM are theoretical numerical and experimental investigations centering on the following subjects: Application, verification and development of continuum-mechanical strength and failure concepts on the basis of the J-integral, and analysis of dynamic loads and load characteristics. The results obtained are presented in this report in the three main sections entitled 'Loads', 'Materials characteristics', and 'Applicability'. (orig.). With 62 figs., 3 tabs., 73 refs

  15. The 1991 research program (of the Faculty of Mechanical Engineering)

    Science.gov (United States)

    1991-05-01

    The main research activities and programs are overviewed. The following domains are covered: production techniques, production organization, transportation and storage, mechanical engineering automation, design and construction, ergonomics, design in plastics, thermal mechanics, heat transfer and fluid mechanics, biomedical mechanical engineering, materials science, and technical mechanics and tribology.

  16. Mitochondrial Genome-Knockout Cells Demonstrate a Dual Mechanism of Action for the Electron Transport Complex I Inhibitor Mycothiazole

    Directory of Open Access Journals (Sweden)

    Michael V. Berridge

    2012-04-01

    Full Text Available Mycothiazole, a polyketide metabolite isolated from the marine sponge Cacospongia mycofijiensis, is a potent inhibitor of metabolic activity and mitochondrial electron transport chain complex I in sensitive cells, but other cells are relatively insensitive to the drug. Sensitive cell lines (IC50 0.36–13.8 nM include HeLa, P815, RAW 264.7, MDCK, HeLa S3, 143B, 4T1, B16, and CD4/CD8 T cells. Insensitive cell lines (IC50 12.2–26.5 μM include HL-60, LN18, and Jurkat. Thus, there is a 34,000-fold difference in sensitivity between HeLa and HL-60 cells. Some sensitive cell lines show a biphasic response, suggesting more than one mechanism of action. Mitochondrial genome-knockout ρ0 cell lines are insensitive to mycothiazole, supporting a conditional mitochondrial site of action. Mycothiazole is cytostatic rather than cytotoxic in sensitive cells, has a long lag period of about 12 h, and unlike the complex I inhibitor, rotenone, does not cause G2/M cell cycle arrest. Mycothiazole decreases, rather than increases the levels of reactive oxygen species after 24 h. It is concluded that the cytostatic inhibitory effects of mycothiazole on mitochondrial electron transport function in sensitive cell lines may depend on a pre-activation step that is absent in insensitive cell lines with intact mitochondria, and that a second lower-affinity cytotoxic target may also be involved in the metabolic and growth inhibition of cells.

  17. Blood flow mechanics and oxygen transport and delivery in the retinal microcirculation: multiscale mathematical modeling and numerical simulation.

    Science.gov (United States)

    Causin, Paola; Guidoboni, Giovanna; Malgaroli, Francesca; Sacco, Riccardo; Harris, Alon

    2016-06-01

    The scientific community continues to accrue evidence that blood flow alterations and ischemic conditions in the retina play an important role in the pathogenesis of ocular diseases. Many factors influence retinal hemodynamics and tissue oxygenation, including blood pressure, blood rheology, oxygen arterial permeability and tissue metabolic demand. Since the influence of these factors on the retinal circulation is difficult to isolate in vivo, we propose here a novel mathematical and computational model describing the coupling between blood flow mechanics and oxygen ([Formula: see text]) transport in the retina. Albeit in a simplified manner, the model accounts for the three-dimensional anatomical structure of the retina, consisting in a layered tissue nourished by an arteriolar/venular network laying on the surface proximal to the vitreous. Capillary plexi, originating from terminal arterioles and converging into smaller venules, are embedded in two distinct tissue layers. Arteriolar and venular networks are represented by fractal trees, whereas capillary plexi are represented using a simplified lumped description. In the model, [Formula: see text] is transported along the vasculature and delivered to the tissue at a rate that depends on the metabolic demand of the various tissue layers. First, the model is validated against available experimental results to identify baseline conditions. Then, a sensitivity analysis is performed to quantify the influence of blood pressure, blood rheology, oxygen arterial permeability and tissue oxygen demand on the [Formula: see text] distribution within the blood vessels and in the tissue. This analysis shows that: (1) systemic arterial blood pressure has a strong influence on the [Formula: see text] profiles in both blood and tissue; (2) plasma viscosity and metabolic consumption rates have a strong influence on the [Formula: see text] tension at the level of the retinal ganglion cells; and (3) arterial [Formula: see text] permeability has a strong influence on the [Formula: see text] saturation in the retinal arterioles. PMID:26232093

  18. Transport phenomena

    International Nuclear Information System (INIS)

    Some simple remarks on the basis of transport theory. - Entropy, dynamics and scattering theory. - Response, relaxation and fluctuation. - Fluctuating hydrodynamics and renormalization of susceptibilities and transport coefficients. - Irreversibility of the transport equations. - Ergodic theory and statistical mechanics. - Correlation functions in Heisenberg magnets. - On the Enskog hard-sphere kinetic eqquation and the transport phenomena of dense simple gases. - What can one learn from Lorentz models. - Conductivity in a magnetic field. - Transport properties in gases in presence of external fields. - Transport properties of dilute gases with internal structure. (orig.)

  19. Structure and Mechanism of Proton Transport Through the Transmembrane Tetrameric M2 Protein Bundle of the Influenza A Virus

    Energy Technology Data Exchange (ETDEWEB)

    R Acharya; V Carnevale; G Fiorin; B Levine; A Polishchuk; V Balannick; I Samish; R Lamb; L Pinto; et al.

    2011-12-31

    The M2 proton channel from influenza A virus is an essential protein that mediates transport of protons across the viral envelope. This protein has a single transmembrane helix, which tetramerizes into the active channel. At the heart of the conduction mechanism is the exchange of protons between the His37 imidazole moieties of M2 and waters confined to the M2 bundle interior. Protons are conducted as the total charge of the four His37 side chains passes through 2{sup +} and 3{sup +} with a pK{sub a} near 6. A 1.65 {angstrom} resolution X-ray structure of the transmembrane protein (residues 25-46), crystallized at pH 6.5, reveals a pore that is lined by alternating layers of sidechains and well-ordered water clusters, which offer a pathway for proton conduction. The His37 residues form a box-like structure, bounded on either side by water clusters with well-ordered oxygen atoms at close distance. The conformation of the protein, which is intermediate between structures previously solved at higher and lower pH, suggests a mechanism by which conformational changes might facilitate asymmetric diffusion through the channel in the presence of a proton gradient. Moreover, protons diffusing through the channel need not be localized to a single His37 imidazole, but instead may be delocalized over the entire His-box and associated water clusters. Thus, the new crystal structure provides a possible unification of the discrete site versus continuum conduction models.

  20. Elucidation of Transport Mechanism of Paeoniflorin and the Influence of Ligustilide, Senkyunolide I and Senkyunolide A on Paeoniflorin Transport through Mdck-Mdr1 Cells as Blood–Brain Barrier in Vitro Model

    Directory of Open Access Journals (Sweden)

    Peng-Yi Hu

    2016-03-01

    Full Text Available The objectives of the present investigation were to: (1 elucidate the transport mechanism of paeoniflorin (PF across MDCK-MDR1 monolayers; and (2 evaluate the effect of ligustilide (LIG, senkyunolide I (SENI and senkyunolide A (SENA on the transport of PF through blood–brain barrier so as to explore the enhancement mechanism. Transport studies of PF were performed in both directions, from apical to basolateral side (A→B and from basolateral to apical sides (B→A. Drug concentrations were analyzed by LC-MS/MS. PF showed relatively poor absorption in MDCK-MDR1 cells, apparent permeability coefficients (Papp ranging from 0.587 × 10−6 to 0.705 × 10−6 cm/s. In vitro experiments showed that the transport of PF in both directions was concentration dependent and not saturable. The B→A/A→B permeability ER of PF was more than 2 in the MDCK-MDR1 cells, which indicated that the transport mechanism of PF might be passiv