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Sample records for main transport mechanism

  1. Alveolobronchiolar transport mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Green, G.M.

    1973-01-01

    In this proposed transport mechanism, particles impinging on alveolar surface layer are drawn, probably by random surface tension forces, to macrophages. Then, laden macrophages are transported along with alveolar fluid either via airways or more probably via pores of Kohn from alveolus to alveolus and eventually into ciliated airways. Additionally, lymphatic fluid transported centripetally to centrilobular lymphatics or centrifugally to perilobular lymphatics (on opposite side of fibrous separation of lobules). ''Sumps'' at broncho-alveolar junctions are for movement of macrophages out of alveoli and interstitial locations and into broncho-alveolar junction. Blind-pocket lymphatics are short-cuts to ciliary stream rather than drainages. (These sumps are drainages during flooding but not normally). Tissue fluid passes into lymph system but cellular material does not. Energetic mechanism is respiratory action in which mid-lobular areas would receive maximum deformation, producing the bidirectional movement. This mechanism is the only accounting for bidirectional movement and parallels lymphatic transport in other body areas. Clearance kinetics of particles are 4-phase: (1) deposition in upper airways with 1 to 2 hr clearance, (2) deposition in respiratory bronchioles with moderately rapid clearance, (3) deposition in alveoli and 1 to 14 day clearance via lymphatic short-cut, and (4) long-term retention of particles trapped in septal or perivascular lymphatics or subpleurally. Extended peribronchiolar retention is only in disease states or with heavy particulate burdens. Compartment model documentation is still lacking. Evidence of lymphoid nodules along macrophage pathways suggests mechanism for local immunity.

  2. Nature and main kinds of psychopathological mechanisms

    Directory of Open Access Journals (Sweden)

    Panagiotis Oulis

    2010-12-01

    Full Text Available The paper deals with two central issues in the philosophy of neuroscience and psychiatry, namely those of the nature and the major kinds and types of psychopathological mechanisms. Contrary to a widespread view, I argue that mechanisms are not kinds of systems but kinds of processes unfolding in systems or between systems. More precisely, I argue that psychopathological mechanisms are sets of actions and interactions between brain-systems or circuits as well as between the latter and other systems in one's body and external environment, both physical and social, involved in human psychopathology. According to the kinds of properties of the interacting systems or their component-parts, psychopathological mechanisms may be physical, chemical, biological, psychological, social, or, typically, mixed ones. Furthermore, I focus on two main kinds of psychopathological mechanisms involved in the causation of mental disorders, namely the pathogenetic and pathophysiological ones, stressing the importance of their careful distinction for the integrative understanding of otherwise disparate and apparently incommensurable psychiatric research findings. I illustrate my analysis with an example drawn from contemporary research on the mechanisms of acute psychosis. Finally, I stress the relevance of psychopathological mechanisms to a more scientifi cally-grounded classifi cation of mental disorders.

  3. Main aging mechanisms in Li ion batteries

    Science.gov (United States)

    Broussely, M.; Biensan, Ph.; Bonhomme, F.; Blanchard, Ph.; Herreyre, S.; Nechev, K.; Staniewicz, R. J.

    Some of the aging mechanisms occurring in Li ion batteries, either on rest or on cycling, are described from long-term storage or cycling data. Generally, the most critical part of the cell is the negative electrode/electrolyte interface. Stability of the solid electrolyte interface (SEI), more generally of the passivating layer, must be insured by proper material choice and additives. Excessive growth induces with time a capacity loss corresponding to the lithium corrosion, and a reduction of power capability of the electrode, from the active surface area degradation. In a worst case, reduction of charge rate capability may lead to local lithium plating during cycling, strongly aggravating the capacity fading. When the SEI is correctly built, with low electronic conductivity, the negative electrode stability can be very stable, as described by long-term aging (more than 4 years) at higher temperature than ambient. Vinylen carbonate is confirmed as outstanding additive. At elevated temperature, high SOC induces side reactions at the positive interface, involving electrolyte components oxidation. The results are an increase of cell impedance, and possible slow CO 2 evolution. Presence of lithium carbonate greatly enhanced the gas formation. The observed impedance increase indicates a reduction of the active surface area, in agreement with solid deposit. When properly designed with an appropriate choice of active materials and electrolyte, the Li ion system can provide a very long service.

  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. 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.

  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

    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 review ...

  7. MAIN DIRECTIONS OF EFFICIENCY IMPROVEMENT OF TRANSPORT INTERCHANGES FUNCTIONING

    Directory of Open Access Journals (Sweden)

    V. Naumov

    2015-07-01

    Full Text Available The article deals with the areas of study concerning transport interchanges. It has been determined that the most perspective directions for the future research is synchronization of the schedule that allous reducing the wating time, preventing the public transport congestion at bus stops and stations, and by doing this to ensure their sustainable development.

  8. Manganese Transport via the Transferrin Mechanism

    OpenAIRE

    Gunter, Thomas E.; Gerstner, Brent; Gunter, Karlene K.; Malecki, Jon; Gelein, Robert; Valentine, William M.; Aschner, Michael; Yule, David I.

    2012-01-01

    Excessive manganese (Mn) uptake by brain cells, particularly in regions like the basal ganglia, can lead to toxicity. Mn2+ is transported into cells via a number of mechanisms, while Mn3+ is believed to be transported similarly to iron (Fe) via the transferrin (Tf) mechanism. Cellular Mn uptake is therefore determined by the activity of the mechanisms transporting Mn into each type of cell and by the amounts of Mn2+, Mn3+ and their complexes to which these cells are exposed; this complicates ...

  9. Maine.

    Science.gov (United States)

    Newberg, Peg

    1992-01-01

    Discusses programs sponsored by groups that promote history instruction in the state of Maine. Reports recent developments concerning Maine's social studies curriculum. Underscores the significance of and financial problems facing "Maine's Common Core of Learning," a program setting out what the state's youth should know in the twenty-first…

  10. 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

  11. Introduction to fluid mechanics and transport phenomena

    CERN Document Server

    Hauke, G

    2008-01-01

    This book presents the foundations of fluid mechanics and transport phenomena in a concise way. It is suitable as an introduction to the subject as it contains many examples, proposed problems and a chapter for self-evaluation. The solutions to all problems are displayed in the corresponding appendix. The content is divided into four parts: fundamentals, conservation principles, dimensional analysis and transport phenomena at interfaces. The transport phenomena of momentum, heat and mass are presented from a rigorous fluid mechanics point of view, and they are explained using a unified, system

  12. Ethanol as a Future Fuel for Road Transportation : Main report

    OpenAIRE

    Larsen, Ulrik; Johansen, Troels; Schramm, Jesper

    2011-01-01

    IEA Implementing Agreement on Advanced Motor Fuels. This report is financed by the Danish Energy Authority (EFP 2006 — Ethanol som motorbrændstof) and made in cooperation with the International Energy Agency — Advanced Motor Fuels Agreement. The report is a contribution to Annex XXXV: “Ethanol as a Motor Fuel — Subtask 1: Ethanol as a Fuel in Road Vehicles.” The work has been carried out by The Technical University of Denmark, Department of Mechanical Engineering.

  13. 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.

  14. Structure and Mechanism of a Nitrate Transporter

    Directory of Open Access Journals (Sweden)

    Hanchi Yan

    2013-03-01

    Full Text Available The nitrate/nitrite transporters NarK and NarU play an important role in nitrogen homeostasis in bacteria and belong to the nitrate/nitrite porter family (NNP of the major facilitator superfamily (MFS fold. The structure and functional mechanism of NarK and NarU remain unknown. Here, we report the crystal structure of NarU at a resolution of 3.1 Å and systematic biochemical characterization. The two molecules of NarU in an asymmetric unit exhibit two distinct conformational states: occluded and partially inward-open. The substrate molecule nitrate appears to be coordinated by four highly conserved, charged, or polar amino acids. Structural and biochemical analyses allowed the identification of key amino acids that are involved in substrate gating and transport. The observed conformational differences of NarU, together with unique sequence features of the NNP family transporters, suggest a transport mechanism that might deviate from the canonical rocker-switch model.

  15. 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.

  16. Main mechanical and thermal problems of the FTU tokamak machine

    International Nuclear Information System (INIS)

    The FTU tokamak in order to reach the expected performance will have to operate steadily at high magnetic fields. Its magnet and vacuum chamber will undergo very high stresses due to thermal and electromagnetic loads for a large number of shots. In order to assess the feasibility of these components, numerical codes tocompute current, magnetic field and temperature distributions and extensive three dimensional finite element stress analysis have been developed. The main results obtained are illustrated. (orig.)

  17. 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 G

  18. 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

  19. Prenatal caffeine exposure induced a lower level of fetal blood leptin mainly via placental mechanism.

    Science.gov (United States)

    Wu, Yi-Meng; Luo, Han-Wen; Kou, Hao; Wen, Yin-Xian; Shen, Lang; Pei, Ling-Guo; Zhou, Jin; Zhang, Yuan-Zhen; Wang, Hui

    2015-11-15

    It's known that blood leptin level is reduced in intrauterine growth retardation (IUGR) fetus, and placental leptin is the major source of fetal blood leptin. This study aimed to investigate the decreased fetal blood leptin level by prenatal caffeine exposure (PCE) and its underlying placental mechanisms. Pregnant Wistar rats were intragastrically administered caffeine (30-120mg/kgday) from gestational day 9 to 20. The level of fetal serum leptin and the expression of placental leptin-related genes were analyzed. Furthermore, we investigated the molecular mechanism of the reduced placental leptin's expression by treatment with caffeine (0.8-20?M) in the BeWo cells. In vivo, PCE significantly decreased fetal serum leptin level in caffeine dose-dependent manner. Meanwhile, placental mRNA expression of adenosine A2a receptor (Adora2a), cAMP-response element binding protein (CREB), a short-type leptin receptor (Ob-Ra) and leptin was reduced in the PCE groups. In vitro, caffeine significantly decreased the mRNA expression of leptin, CREB and ADORA2A in concentration and time-dependent manners. The addition of ADORA2A agonist or adenylyl cyclase (AC) agonist reversed the inhibition of leptin expression induced by caffeine. PCE induced a lower level of fetal blood leptin, which the primary mechanism is that caffeine inhibited antagonized Adora2a and AC activities to decreased cAMP synthesis, thus inhibited the expression of the transcription factor CREB and target gene leptin in the placenta. Meantime, the reduced transportation of maternal leptin by placental Ob-Ra also contributed to the reduced fetal blood leptin. Together, PCE decreased fetal blood leptin mainly via reducing the expression and transportation of leptin in the placenta. PMID:26367767

  20. Rat hepatocytes transport water mainly via a non-channel-mediated pathway.

    Science.gov (United States)

    Yano, M; Marinelli, R A; Roberts, S K; Balan, V; Pham, L; Tarara, J E; de Groen, P C; LaRusso, N F

    1996-03-22

    During bile formation by the liver, large volumes of water are transported across two epithelial barriers consisting of hepatocytes and cholangiocytes (i.e. intrahepatic bile duct epithelial cells). We recently reported that a water channel, aquaporin-channel-forming integral protein of 28 kDa, is present in cholangiocytes and suggested that it plays a major role in water transport by these cells. Since the mechanisms of water transport across hepatocytes remain obscure, we performed physiological, molecular, and biochemical studies on hepatocytes to determine if they also contain water channels. Water permeability was studied by exposing isolated rat hepatocytes to buffers of different osmolarity and measuring cell volume by quantitative phase contrast, fluorescence and laser scanning confocal microscopy. Using this method, hepatocytes exposed to hypotonic buffers at 23 degrees C increased their cell volume in a time and osmolarity-dependent manner with an osmotic water permeability coefficient of 66.4 x 10(-4) cm/s. In studies done at 10 degrees C, the osmotic water permeability coefficient decreased by 55% (p < 0.001, at 23 degrees C; t test). The derived activation energy from these studies was 12.8 kcal/mol. After incubation of hepatocytes with amphotericin B at 10 degrees C, the osmotic water permeability coefficient increased by 198% (p < 0.001) and the activation energy value decreased to 3.6 kcal/mol, consistent with the insertion of artificial water channels into the hepatocyte plasma membrane. Reverse transcriptase polymerase chain reaction with hepatocyte RNA as template did not produce cDNAs for three of the known water channels. Both the cholesterol content and the cholesterol/phospholipid ratio of hepatocyte plasma membranes were significantly (p < 0.005) less than those of cholangiocytes; membrane fluidity of hepatocytes estimated by measuring steady-state anisotropy was higher than that of cholangiocytes. Our data suggests that the osmotic flow of water across hepatocyte membranes occurs mainly by diffusion via the lipid bilayer (not by permeation through water channels as in cholangiocytes). PMID:8636089

  1. 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.)

  2. 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

  3. 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)

  4. Detection of Explosives by Nqr Method: Main Aspects for Transport Security

    Science.gov (United States)

    Rudakov, Taras N.

    The main aspects specific to the Nuclear Quadrupole Resonance (NQR) application for the transport security are analyzed and discussed. The continuing efforts to improve the function of the NQR based Explosive Detection Systems (EDS) through a more sensitive detection are described. The methods of reducing false alarm events generated from the RF excitation and interference are presented and discussed. The operational features of the NQR scanners are also presented and discussed.

  5. Mechanism of ochratoxin A transport in kidney

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-08-01

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

  6. 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...

  7. [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

  8. 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

  9. Mesoscopic mechanism of adiabatic charge transport

    CERN Document Server

    Zhou, F; Altshuler, B L

    1998-01-01

    We consider adiabatic charge transport through mesoscopic metallic samples caused by a periodically changing external potential. We find that both the amplitude and the sign of the charge transferred through a sample per period are random sample specific quantities. The characteristic magnitude of the charge is determined by the quantum interference.

  10. 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??m 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.

  11. Transport mechanisms of contaminants released from fine sediment in rivers

    Science.gov (United States)

    Cheng, Pengda; Zhu, Hongwei; Zhong, Baochang; Wang, Daozeng

    2015-09-01

    Contaminants released from sediment into rivers are one of the main problems to study in environmental hydrodynamics. For contaminants released into the overlying water under different hydrodynamic conditions, the mechanical mechanisms involved can be roughly divided into convective diffusion, molecular diffusion, and adsorption/desorption. Because of the obvious environmental influence of fine sediment (D_{90}= 0.06 mm), non-cohesive fine sediment, and cohesive fine sediment are researched in this paper, and phosphorus is chosen for a typical adsorption of a contaminant. Through theoretical analysis of the contaminant release process, according to different hydraulic conditions, the contaminant release coupling mathematical model can be established by the N-S equation, the Darcy equation, the solute transport equation, and the adsorption/desorption equation. Then, the experiments are completed in an open water flume. The simulation results and experimental results show that convective diffusion dominates the contaminant release both in non-cohesive and cohesive fine sediment after their suspension, and that they contribute more than 90 % of the total release. Molecular diffusion and desorption have more of a contribution for contaminant release from unsuspended sediment. In unsuspension sediment, convective diffusion is about 10-50 times larger than molecular diffusion during the initial stages under high velocity; it is close to molecular diffusion in the later stages. Convective diffusion is about 6 times larger than molecular diffusion during the initial stages under low velocity, it is about a quarter of molecular diffusion in later stages, and has a similar level with desorption/adsorption. In unsuspended sediment, a seepage boundary layer exists below the water-sediment interface, and various release mechanisms in that layer mostly dominate the contaminant release process. In non-cohesive fine sediment, the depth of that layer increases linearly with shear stress. In cohesive fine sediment, the range seepage boundary is different from that in non-cohesive sediment, and that phenomenon is more obvious under a lower shear stress.

  12. 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

    Introduction: Many drug substances are substrates for membrane transporters, which influence their intestinal absorption. Vigabatrin is a drug substance used in the treatment of epilepsy, mainly for treatment of infantile spasms. Vigabatrin is a substrate for the human proton-coupled amino acid 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...

  13. Quantum mechanisms of density wave transport

    International Nuclear Information System (INIS)

    We report on new developments in the quantum picture of correlated electron transport in charge and spin density waves. The model treats the condensate as a quantum fluid in which charge soliton domain wall pairs nucleate above a Coulomb blockade threshold field. We employ a time-correlated soliton tunneling model, analogous to the theory of time-correlated single electron tunneling, to interpret the voltage oscillations and nonlinear current-voltage characteristics above threshold. An inverse scaling relationship between threshold field and dielectric response, originally proposed by Grüner, emerges naturally from the model. Flat dielectric and other ac responses below threshold in NbSe3 and TaS3, as well as small density wave phase displacements, indicate that the measured threshold is often much smaller than the classical depinning field. In some materials, the existence of two distinct threshold fields suggests that both soliton nucleation and classical depinning may occur. In our model, the ratio of electrostatic charging to pinning energy helps determine whether soliton nucleation or classical depinning dominates.

  14. Transport mechanisms in nanopores and nanochannels: can we mimic nature?

    Directory of Open Access Journals (Sweden)

    Mario Tagliazucchi

    2015-04-01

    Full Text Available The last few years have witnessed major advancements in the synthesis, modification, characterization and modeling of nanometer-size solid-state channels and pores. Future applications in sensing, energy conversion and purification technologies will critically rely on qualitative improvements in the control over the selectivity, directionality and responsiveness of these nanochannels and nanopores. It is not surprising, therefore, that researchers in the field seek inspiration in biological ion channels and ion pumps, paradigmatic examples of transport selectivity. This work reviews our current fundamental understanding of the mechanisms of transport of ions and larger cargoes through nanopores and nanochannels by examining recent experimental and theoretical work. It is argued that that structure and transport in biological channels and polyelectrolyte-modified synthetic nanopores are strongly coupled: the structure dictates transport and transport affects the structure. We compare synthetic and biological systems throughout this review to conclude that while they present interesting similarities, they also have striking differences.

  15. 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. 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

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

    OpenAIRE

    Sánchez-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...

  17. Remote controlled apparatus comprising a main motor unit and a slave unit for transporting contaminated substances

    International Nuclear Information System (INIS)

    This invention describes an apparatus for transporting objects over a previously determined path, in particular a transport apparatus that can be remotely controlled and powered from a distance that is suitable for use in contaminated areas. The aim of this invention is to suggest a transport appliance capable of treating or transporting contaminated substances and in which the parts of the apparatus, which are the most likely to require maintenance whilst in use, are not exposed to contamination

  18. [Vesicular intracellular transport in the digestive organs. Membrane vesicle--the universal mechanism of the functional transport].

    Science.gov (United States)

    Morozov, I A

    2014-01-01

    On the basis of long-term research of the morpho-functional characteristics of the cells of the stomach, small intestine and gallbladder the mechanism and function of membrane vesicles in the implementation of the main functions of these organs sets out in this article: the secretion of hydrochloric acid by parietal cells, the absorption of nutrients in the small intestine and the fluid at a concentration of bile epitheliocytes of gallbladder. Proofs of the intracellular formation of hydrochloric acid in tubulovesicles of the parietal cells and turnover of its secretory membranes in the process of secretory cycle, that has ensured the re-use and explained the extraordinary life of these unique cells are presented. The credible mechanism of HCl output oppression by H(+)-K(+)-ATPase activity blockers has set out on this basis. The article provides detailed endocytosis mechanism of the ions and nutrients absorption by enterocytes. The mechanism of participation of the apical contractile complex of brush border of epithelial cells in the initiation of endocytosis and cytoplasmic microtubules in transport of membrane vesicles in the cytoplasm was analyzed. Based on our research and numerous of the world scientific proceedings the conclusion was done about the existence of two energy dependent types of transport in the absorptive epithelium of the digestive--transmembrane (ionic and nutritive) homeostatic type which is realized by the ATP-system of the basal plasmalemma, and vesicular (endocytosis) type which is impltmented by apical contractile complex of brush border and cytoplasmic microtubules. Both types of transport are interrelated and are under constant cellular control. This observation is relevant to the majority of cells, including those involved in the secretion of various substances: hydrochloric acid by parietal cells, enzymes by main cells of the gastric glands and exocrinocytes of the pancreas, hormone by endocrine cells of the APUD system and, finally, mediators by nerve cells. To clarify the problem of cell transport two types: homeostatic and functional transport should be distinguished. The first type is carried out mainly in relation to ions on basolateral membrane with the help of its ATPase systems and provides intracellular homeostasis and nutritive co- transportation, the second (functional) type defines the basic specific function by means of membrane vesicles. PMID:25518468

  19. Catalyst transport in corn stover internodes: elucidating transport mechanisms using Direct Blue-I.

    Science.gov (United States)

    Viamajala, Sridhar; Selig, Michael J; Vinzant, Todd B; Tucker, Melvin P; Himmel, Michael E; McMillan, James D; Decker, Stephen R

    2006-01-01

    The transport of catalysts (chemicals and enzymes) within plant biomass is believed to be a major bottleneck during thermochemical pretreatment and enzymatic conversion of lignocellulose. Subjecting biomass to size reduction and mechanical homogenization can reduce catalyst transport limitations; however, such processing adds complexity and cost to the overall process. Using high-resolution light microscopy, we have monitored the transport of an aqueous solution of Direct Blue-I (DB-I) dye through intact corn internodes under a variety of impregnation conditions. DB-I is a hydrophilic anionic dye with affinity for cellulose. This model system has enabled us to visualize likely barriers and mechanisms of catalyst transport in corn stems. Microscopic images were compared with calculated degrees of saturation (i.e., volume fraction of internode void space occupied by dye solution) to correlate impregnation strategies with dye distribution and transport mechanisms. Results show the waxy rind exterior and air trapped within individual cells to be the major barriers to dye transport, whereas the vascular bundles, apoplastic continuum (i.e., the intercellular void space at cell junctions), and fissures formed during the drying process provided the most utilized pathways for transport. Although representing only 20-30% of the internode volume, complete saturation of the apoplast and vascular bundles by fluid allowed dye contact with a majority of the cells in the internode interior. PMID:16915666

  20. 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 suggested to increase coordination between core stakeholders within passenger railway services and bus services. Four distinctive mechanisms of coordination are suggested, namely organisational coordina...

  1. 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 suggested to increase coordination between core stakeholders within passenger railway services and bus services. Four distinctive mechanisms of coordination are suggested, namely organisational coordina...

  2. Perturbations to SOC models as a mechanism for transport control

    International Nuclear Information System (INIS)

    Recently the concept of Self-Organized Criticality (SOC) was advanced as a paradigm for turbulent transport in magnetically confined plasmas. The type of model has the advantage of predicting general features of the transport dynamics and profiles independent of the local instability driving the fluctuations. Such a model predicts profile resiliency, sub-marginal profiles maintaining active transport, intermittency in flux and transport events which have large correlation lengths while the underlying fluctuations have short correlation lengths. Given that many of these features have been observed in experiments, an investigation is made of the dynamics of a perturbed SOC system as a mechanism for the control of transport. One of the problems faced by magnetic confinement devices is the control of the heat and particle fluxes. If the fluxes are very open-quotes burstyclose quotes then even if the walls and divertor can safely absorb the average flux the instantaneous flux could damage or destroy these surfaces. Additionally, in enhanced confinement regimes (H-mode, VH-mode, Enhanced Reversed Shear modes and such) the limiting factor is often the buildup of a super-critical gradient which gives rise to a sudden large transport event. Computational experiments with a sandpile model of SOC dynamics suggests that some modification of the transport dynamics may be possible with periodic perturbations of the internal sources

  3. Mechanism of destruction of transport barriers in geophysical jets with Rossby waves

    CERN Document Server

    Uleysky, M Yu; Prants, S V; 10.1103/PhysRevE.81.017202

    2012-01-01

    The mechanism of destruction of a central transport barrier in a dynamical model of a geophysical zonal jet current in the ocean or the atmosphere with two propagating Rossby waves is studied. We develop a method for computing a central invariant curve which is an indicator of existence of the barrier. Breakdown of this curve under a variation of the Rossby wave amplitudes and onset of chaotic cross-jet transport happen due to specific resonances producing stochastic layers in the central jet. The main result is that there are resonances breaking the transport barrier at unexpectedly small values of the amplitudes that may have serious impact on mixing and transport in the ocean and the atmosphere. The effect can be found in laboratory experiments with azimuthal jets and Rossby waves in rotating tanks under specific values of the wave numbers that are predicted in the theory.

  4. Modeling Transport and Flow Regulatory Mechanisms of the Kidney

    Science.gov (United States)

    Layton, Anita T.

    2013-01-01

    The kidney plays an indispensable role in the regulation of whole-organism water balance, electrolyte balance, and acid-base balance, and in the excretion of metabolic wastes and toxins. In this paper, we review representative mathematical models that have been developed to better understand kidney physiology and pathophysiology, including the regulation of glomerular filtration, the regulation of renal blood flow by means of the tubuloglomerular feedback mechanisms and of the myogenic mechanism, the urine concentrating mechanism, and regulation of renal oxygen transport. We discuss how such modeling efforts have significantly expanded our understanding of renal function in both health and disease. PMID:23914303

  5. Mechanism of Transport through Wood Cell Wall Polymers

    Directory of Open Access Journals (Sweden)

    Joseph E Jakes

    2013-11-01

    Full Text Available The movement of chemicals through wood is necessaryfor decay and fastener corrosion to occur in forest products.However, the mechanism responsible for the onset of fastenercorrosion and decay in wood is not known. The onset occursbefore the formation of free water in wood cavities and aqueouschemical transport would be possible. Here, we propose that theonset mechanism is the hemicelluloses going through a moistureinducedglass transition. As nm-scale regions of mechanicallysoftened hemicelluloses in cell walls percolate, pathways forchemical transport are created. The ability of chemicals to movein cell walls enables fastener corrosion and decay to occur. Thismechanism suggests that wood treatments preventing the glasstransition of hemicelluloses will inhibit fastener corrosion andwood decay. The identification of this mechanism shouldaccelerate the development of wood treatments to improve forestproducts durability.

  6. Structure and mechanism of ATP-dependent phospholipid transporters

    DEFF Research Database (Denmark)

    Lopez Marques, Rosa Laura; Poulsen, Lisbeth Rosager

    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. Further, despite differences in overall architecture, both appear to operate by an alternating access mechanism and during transport they might allow access of phospholipids to the internal part of the transmembrane domain. The latter feature is obvious for ABC transporters, but phospholipids and other hydrophobic molecules have also been found embedded in P-type ATPase crystal structures. Taken together, in two diverse groups of pumps, nature appears to have evolved quite similar ways of flipping phospholipids. General significance Our understanding of the structural basis for phospholipid flipping is still limited but it seems plausible that a general mechanism for phospholipid flipping exists in nature. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.

  7. 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.

  8. 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 lubrication in journal bearings helps to enhance the hydrodynamic fluid film by increasing the fluid film thickness and consequently reducing viscous friction losses and vibrations. In this study, the hydrostatic lubrication is modified by injecting oil at controllable pressures through orifices 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 through equations. The global system is numerically solved using as a case study a single-cylinder combustion engine, where the conventional lubrication of the main bearing is modified by applying radial oil injection using piezo-actuated injection. The performance of such a hybrid bearing is compared to an equivalent conventional lubricated bearing in terms of the maximum fluid film pressures, minimum fluid film thicknesses, and reduction of viscous friction losses.

  9. General mechanism for helium blistering involving displaced atom transport

    International Nuclear Information System (INIS)

    A mechanism developed to account for formation of vertically elongated blisters in high displacement environments produced by 252Cf alpha particles and fission fragments has been extended to formation of done-shaped blisters in the low displacement environments produced by simple helium ion beams. In this mechanism, transport of displaced atoms to relieve compressive stresses in the helium-implanted layer allows interconnections of small, subsurface bubbles to form the blister cavity. The same transport may cause thickening of the blister caps at low implantation energies. The transition from dome-shaped to vertically elongated blistering occurs between the 300 and 3000 displacements per helium atom produced by simple helium ions and 252Cf radiations respectively

  10. 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...

  11. 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.

  12. 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.

  13. From PHENIX to SUPER PHENIX: mechanical structures assuring reactor vessel tightness at main sodium pump penetrations

    International Nuclear Information System (INIS)

    It is shown how the mechanical problems concerning the tightness of main sodium pump penetrations through the deck of a pool type reactor have been solved in joint SNECMA - HISPANO-SUIZA/CIRNA studies. Extensive general studies have been performed and a comprehensive dossier of different possible solutions compiled. Whereever appropriate, information has been extrapolated from PHENIX experience. In the solution finally adopted, an elastic torus shaped ring, which forms a ball-and-socket type joint is used. A thin shell structure connects the bottom to the reactor internals in such a way as to permit both vertical and rotational displacements. Studies and calculation have been completed with the realization of a 1/5 scale model of the upper torus ring. Displacement, and angular and axial stiffness measurements have confirmed the validity of the hypotheses. (Auth.)

  14. Transport of Sulfide-Reduced Graphene Oxide in Saturated Quartz Sand: Cation-Dependent Retention Mechanisms.

    Science.gov (United States)

    Xia, Tianjiao; Fortner, John D; Zhu, Dongqiang; Qi, Zhichong; Chen, Wei

    2015-10-01

    We describe how the reduction of graphene oxide (GO) via environmentally relevant pathways affects its transport behavior in porous media. A pair of sulfide-reduced GOs (RGOs), prepared by reducing 10 mg/L GO with 0.1 mM Na2S for 3 and 5 days, respectively, exhibited lower mobility than did parent GO in saturated quartz sand. Interestingly, decreased mobility cannot simply be attributed to the increased hydrophobicity and aggregation upon GO reduction because the retention mechanisms of RGOs were highly cation-dependent. In the presence of Na(+) (a representative monovalent cation), the main retention mechanism was deposition in the secondary energy minimum. However, in the presence of Ca(2+) (a model divalent cation), cation bridging between RGO and sand grains became the most predominant retention mechanism; this was because sulfide reduction markedly increased the amount of hydroxyl groups (a strong metal-complexing moiety) on GO. When Na(+) was the background cation, increasing pH (which increased the accumulation of large hydrated Na(+) ions on grain surface) and the presence of Suwannee River humic acid (SRHA) significantly enhanced the transport of RGO, mainly due to steric hindrance. However, pH and SRHA had little effect when Ca(2+) was the background cation because neither affected the extent of cation bridging that controlled particle retention. These findings highlight the significance of abiotic transformations on the fate and transport of GO in aqueous systems. PMID:26348539

  15. Estimation of the binding ability of main transport proteins of blood plasma with liver cirrhosis by the fluorescent probe method

    Science.gov (United States)

    Korolenko, E. A.; Korolik, E. V.; Korolik, A. K.; Kirkovskii, V. V.

    2007-07-01

    We present results from an investigation of the binding ability of the main transport proteins (albumin, lipoproteins, and ?-1-acid glycoprotein) of blood plasma from patients at different stages of liver cirrhosis by the fluorescent probe method. We used the hydrophobic fluorescent probes anionic 8-anilinonaphthalene-1-sulfonate, which interacts in blood plasma mainly with albumin; cationic Quinaldine red, which interacts with ?-1-acid glycoprotein; and neutral Nile red, which redistributes between lipoproteins and albumin in whole blood plasma. We show that the binding ability of albumin and ?-1-acid glycoprotein to negatively charged and positively charged hydrophobic metabolites, respectively, increases in the compensation stage of liver cirrhosis. As the pathology process deepens and transitions into the decompensation stage, the transport abilities of albumin and ?-1-acid glycoprotein decrease whereas the binding ability of lipoproteins remains high.

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

    OpenAIRE

    I. W. M. Pothof

    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...

  17. 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.

  18. Molecular Mechanisms of Phosphorus Metabolism and Transport during Leaf Senescence

    Directory of Open Access Journals (Sweden)

    Kyla A. Stigter

    2015-12-01

    Full Text Available Leaf senescence, being the final developmental stage of the leaf, signifies the transition from a mature, photosynthetically active organ to the attenuation of said function and eventual death of the leaf. During senescence, essential nutrients sequestered in the leaf, such as phosphorus (P, are mobilized and transported to sink tissues, particularly expanding leaves and developing seeds. Phosphorus recycling is crucial, as it helps to ensure that previously acquired P is not lost to the environment, particularly under the naturally occurring condition where most unfertilized soils contain low levels of soluble orthophosphate (Pi, the only form of P that roots can directly assimilate from the soil. Piecing together the molecular mechanisms that underpin the highly variable efficiencies of P remobilization from senescing leaves by different plant species may be critical for devising effective strategies for improving overall crop P-use efficiency. Maximizing Pi remobilization from senescing leaves using selective breeding and/or biotechnological strategies will help to generate P-efficient crops that would minimize the use of unsustainable and polluting Pi-containing fertilizers in agriculture. This review focuses on the molecular mechanisms whereby P is remobilized from senescing leaves and transported to sink tissues, which encompasses the action of hormones, transcription factors, Pi-scavenging enzymes, and Pi transporters.

  19. Driving mechanism of toroidal rotation and momentum transport in JT-60U

    International Nuclear Information System (INIS)

    The driving mechanism of toroidal rotation and the momentum transport are studied, utilizing nearperpendicular neutral beam injection (PERP-NBI), co tangential and counter tangential NBI in JT-60U. Main results are as follows: (i) fast ion losses due to the toroidal field ripple induce the toroidal rotation in the direction antiparallel to the plasma current, i.e. counter (CTR) direction in the peripheral region, (ii) the magnitude of CTR rotation increases with increasing the ripple loss power in the peripheral region. (iii) Diffusive and non-diffusive terms of momentum transport are evaluated from the transient analysis by using the momentum source modulation experiment. Fast ion losses which locally induce the edge CTR rotation have been used as a novel momentum source. (iv) Parameter dependence of these transport coefficients i.e. the toroidal momentum diffusivity ?? and the convection velocity Vconv, and the relation between heat and momentum diffusivities are investigated in L and H-mode plasmas systematically. The toroidal momentum diffusivity increases with increasing heating power, and decreases with increasing the plasma current in L-mode plasmas. The H-mode exhibits momentum diffusivity better than L-mode. Experiments indicate a positive correlation between the momentum and thermal transport at constant density. (v) We have also found that toroidal rotation velocity profiles in low .. plasmas can be almost explained by momentum transport considering diffusivity and convective velocity estimated from the transient momentum transport analysis. (author)

  20. Study of internal transport barrier triggering mechanism in tokamak plasmas

    International Nuclear Information System (INIS)

    Sheared flow layers driven by magnetic energy, released in tearing-reconnection processes inherent in dissipative magnetohydrodynamics, are proposed as a triggering mechanism for the creation of the internal transport barrier (ITB) in tokamak plasmas. The double tearing mode, mediated by anomalous electron viscosity in configurations with a nonmonotonic safety factor, is investigated as an example. Particular emphasis is placed on the formation of sheared poloidal flow layers in the vicinity of the magnetic islands. A quasilinear simulation demonstrates that the sheared flows induced by the mode have desirable characteristics (lying just outside the magnetic islands), and sufficient levels required for ITB formation. A possible explanation is also proffered for the experimental observation that the transport barriers are preferentially formed in the proximity of low-order rational surfaces

  1. [Mechanical stress of newborn infants caused by incubator transport].

    Science.gov (United States)

    Boenisch, H; Gaden, W; Mau, G; Gohrbandt, U; Teuteberg, H O; Braun, H; Beermann, H J

    1985-07-01

    Newborn babies transported in an incubator are obviously exposed to considerable mechanical vibrations. We measured these vibrations with the aim to improve these conditions. The vibrations measured on transportation by R.T.W. ambulance (Daimler-Benz 508 with an "anti-vibration platform") are almost tolerable; however on the K.T.W. ambulance (Volkswagen Type 2) the registered vertical accelerations were much greater and gave an unacceptable level of gravitational forces. Small constructive corrections to the stretcher and the connection between stretcher and incubator lead to a marked decrease in peak acceleration and the value of effective acceleration. We also found that it is of great importance to drive smoothly and that the vibrations are more pronounced with hasty driving. The influence of these vibrations as a possible co-factor in the pathogenesis of intracranial haemorrhage is discussed. PMID:4047059

  2. Nonlinear charge transport mechanism in periodic and disordered DNA

    CERN Document Server

    Hennig, D; Agarwal, J P

    2003-01-01

    We study a model for polaron-like charge transport mechanism along DNA molecules with emphasis on the impact of parametrical and structural disorder. Our model Hamiltonian takes into account the coupling of the charge carrier to two different kind of modes representing fluctuating twist motions of the base pairs and H-bond distortions within the double helix structure of $\\lambda-$DNA. Localized stationary states are constructed with the help of a nonlinear map approach for a periodic double helix and in the presence of intrinsic static parametrical and/or structural disorder reflecting the impact of ambient solvent coordinates. It is demonstrated that charge transport is mediated by moving polarons respectively breather compounds carrying not only the charge but causing also local temporal deformations of the helix structure through the traveling torsion and bond breather components illustrating the interplay of structure and function in biomolecules.

  3. 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).

  4. 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

  5. Mechanical transport in two-dimensional networks of fractures

    Energy Technology Data Exchange (ETDEWEB)

    Endo, H.K.

    1984-04-01

    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.

  6. 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.

  7. 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 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 ret...

  8. Double internal transport barrier triggering mechanism in tokamak plasmas

    International Nuclear Information System (INIS)

    Sheared flow layers created by energy released in magnetic reconnection processes are studied with the magneto hydrodynamics (MHD), aimed at internal transport barrier (ITB) dynamics. The double tearing mode induced by electron viscosity is investigated and proposed as a triggering mechanism for double internal transport barrier (DITB) observed in tokamak plasmas with non-monotonic safety factor profiles. The quasi-linear development of the mode is simulated and the emphasis is placed on the structure of sheared poloidal flow layers formed in the vicinity of the magnetic islands. For viscosity double tearing modes, it is shown that the sheared flows induced by the mode may reach the level required by the condition for ITB formation. Especially, the flow layers are found to form just outside the magnetic islands. The scaling of the generated velocity with plasma parameters is given. Possible explanation for the experimental observations that the preferential formation of transport barriers in the proximity of low order rational surface is discussed. (author)

  9. Calcium transport mechanism in molting crayfish revealed by microanalysis

    International Nuclear Information System (INIS)

    Crayfish provide a good model in which to study the transport mechanism of Ca ions. During the molting stage, decalcified Ca ions are transferred into the blood and accumulate in the gastrolith epithelium, after which a gastrolith is formed on the surface of the epithelium. The gastrolith is dissolved in the stomach after molting, and the Ca is reabsorbed and redistributed throughout the newly formed exoskeleton. We studied the mechanism of Ca transport by cytochemical precipitation of Ca ions and by electron microanalysis, including X-ray microanalysis (EDX) and electron energy-loss spectroscopy (EELS), with a computer. In EDX analysis, the fine precipitates of K-antimonate in the gastrolith mitochondria clearly defined Ca with antimony; we also observed a large amount of Ca-oxalate in the mitochondria, and Ca-K X-ray pulses were clearly defined. Ca-K X-rays were also detected from fresh freeze-substituted mitochondria. Finally, we succeeded in taking a Ca-L EELS image from the mitochondria of fresh freeze-substituted thin sections. Only a very small amount of Ca was detected from the cell membrane and other organelles. Ca-adenosine triphosphatase (ATPase) and Mg-ATPase activity was also very clearly demonstrated in the mitochondria. These enzymes may play an important role in Ca metabolism

  10. Bioturbation as a mechanism for radionuclide transport in soil: relevance of earthworms

    Energy Technology Data Exchange (ETDEWEB)

    Mueller-Lemans, H. [Tergeso AG, Sargans (Switzerland); Dorp, F. van [NAGRA, Wettingen (Switzerland)

    1996-07-01

    In the context of safety analyses performed for radioactive waste repositories, one important group of scenarios assumes that radionuclides escaping from a repository will reach the biosphere via groundwater. Consequently, when calculating radionuclide migration in the biosphere, most of the models used to date concentrate on transport in the liquid phase. In the soil, however, transport in the solid phase can also be important, particularly when burrowing animals displace the soil together with sorbed and low-solubility radionuclides. Given the conditions prevailing in agricultural areas of central Europe, it is mainly earthworms which play a significant role in material displacement and these will be the subject of this report. A numerical example is used to present the equations which, for given distribution coefficients, can be applied to calculate the portions of the transfer coefficient which can be attributed to transport in the liquid and solid phases. The results demonstrate that material transport by soil fauna, and particularly by earthworms, is a relevant mechanism in many cases, especially for the upward transport of strongly sorbing radionuclides. It should therefore be considered in biosphere models. (Author).

  11. Exciton delocalization and energy transport mechanisms in R-phycoerythrin.

    Science.gov (United States)

    Womick, Jordan M; Liu, Haoming; Moran, Andrew M

    2011-03-31

    Energy transport mechanisms in R-Phycoerythrin (RPE), a light harvesting protein located at the top of the phycobilisome antenna in red algae, are investigated using nonlinear optical spectroscopies and theoretical models. The RPE hexamer possesses a total of 30 bilin pigments, which can be subdivided into three classes based on their molecular structures and electronic resonance frequencies. Of particular interest to this study is the influence of exciton delocalization on the real-space paths traversed by photoexcitations as they concentrate on the lowest energy pigment sites. Transient grating measurements show that significant nuclear relaxation occurs at delay times less than 100 fs, whereas energy transport spans a wide range of time scales depending on the proximity of the initial and final states involved in the process. The fastest energy transport dynamics within the RPE complex are close to 1 ps; however, evidence for sub-100 fs exciton self-trapping is also obtained. In addition, photon echo experiments reveal vibronic interactions with overdamped and underdamped nuclear modes. To establish signatures of exciton delocalization, energy transport is simulated using both modified Redfield and Fo?rster theories, which respectively employ delocalized and localized basis states. We conclude that exciton delocalization occurs between six pairs of phycoerythrobilin pigments (i.e., dimers) within the protein hexamer. It is interesting that these dimers are bound in locations analogous to the well-studied phycocyanobilin dimers of cyanobacterial allophycocyanin and c-phycocyanin in which wave function delocalization is also known to take hold. Strong conclusions regarding the electronic structures of the remaining pigments cannot be drawn based on the present experiments and simulations due to overlapping resonances and broad spectroscopic line widths, which prevent the resolution of dynamics at particular pigment sites. PMID:21381708

  12. HYDROLOGICAL AND SEDIMENT TRANSPORT SIMULATION TO ASSESS THE IMPACT OF DAM CONSTRUCTION IN THE MEKONG RIVER MAIN CHANNEL

    Directory of Open Access Journals (Sweden)

    Satoshi Kameyama

    2013-01-01

    Full Text Available The downstream impact of dams is a complex problem in watershed management. In the upper Mekong River watershed and its main channel, dam construction projects were started in the 1950s to meet increasing demands for energy and food production. Dams called the Mekong Cascade were completed on the Mekong River in China, the Manwan Dam in 1996 and the Dachaoshan Dam in 2003. We evaluated the impact of the Manwan Dam and its related watershed development on seasonal water discharge and suspended sediment transportation using hydrological simulations of target years 1991 (before dam construction and 2002 (after dam completion. Our study area was the main channel of the Mekong River in northern Thailand extending about 100 km downstream from the intersection of Myanmar, Thailand and Laos. We used the MIKE SHE and MIKE11 (Enterprise models to calculate seasonal changes of water discharge and sediment transport at five points 15-35-km apart in this interval. Sediment load was calculated from a regression equation between sediment load and water discharge, using suspended sediment concentrations in monthly river water samples taken between November 2007 and November 2008. Finally we estimated annual sediment load along the study reach using from both of simulated annual hydrograph and the regression equation. Our simulations showed that after construction of the dam, there was a moderate decrease in peak discharge volume and during the rainy season in August and September and a corresponding increase in the subsequent months. Accordingly, sediment transportation budgets were increased in months after the rainy season. The suspended sediment transportation in Chiang Sean was increased from 21.13 to 27.90 (M ton/year in our model condition.

  13. Synthesis, characterization and charge transport mechanism of CdZnO nanorods

    International Nuclear Information System (INIS)

    ZnO and Cd-doped ZnO nanostructures were prepared by new facile method at 80 deg. C. XRD measurement indicated that both samples had typical hexagonal wurtzite structures. Transmission electron microscopy (TEM) measurement shows that rod-like crystals have been formed. EDX measurement confirms the incorporation of the cadmium ion into the crystalline lattice of ZnO and indicated that cadmium ions uniformly distributed on the surface of the rods. The doping with cadmium ions has a great influence on the optical properties of the ZnO. The electrical measurements of Cd-doped ZnO nanorod were measured. The current-voltage (I-V) characteristic curve revealed that the charge transport above 4 V is mainly non-linear due to grain boundary contribution. The complex impedance spectroscopy was confirmed that the grain boundary effect controls the charge transport mechanism through CdZnO ceramic material.

  14. 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.

  15. 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

  16. 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

  17. Mechanical reliability of geometrically imperfect tubular oxygen transport membranes

    DEFF Research Database (Denmark)

    Kwok, Kawai; Frandsen, Henrik Lund

    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 of imperfections in the tubular membrane geometry. A supported membrane made of dense and porous Zr-doped-BSCF is studied as an illustrative example. It is shown that stresses induced by oxygen stoichiometry gradients relax over time due to creep and external pressure is the dominating source of stress in the long term. Therefore, creep has no adverse effect for geometrically perfect membranes. For geometrically imperfect membranes, curl and eccentricity are found to have insignificant influence on fracture risk while ovality is identified as the most critical geometric imperfection. Under the influence of external pressure, ovality may lead to dramatic stress increase and flattening of oval cross sections. Oval membranes can fail in the long term even though the instantaneous fracture risk is tolerable. Based on industrial relevant conditions, the requirements to the material creep rate and component quality (in terms of specification of tolerable deviation from perfect tubular shape) that allows fail-safe operation are deduced.

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

    Science.gov (United States)

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

    2014-12-01

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

  19. 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.

  20. 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.

  1. A comparison of mechanisms generating vertical transport in the Brazilian coastal upwelling regions

    Science.gov (United States)

    Mazzini, P. L. F.; Barth, J. A.

    2013-11-01

    Several mechanisms can drive vertical velocities in the coastal ocean, including wind-forcing and through gradients in the vorticity field generated by flow-topography interactions. A two-layer, steady, wind-driven, analytical model is applied to the major upwelling systems of Brazil: Cabo Frio (CF) and Cabo de Santa Marta (CSM) regions. Comparisons are made between the relative roles of wind and flow-topography interaction in inducing upwelling over these regions. Ekman pumping is the weakest mechanism over the shelf, but does influence the along-shelf temperature in the CF area. Away from coastline irregularities, wind-driven upwelling (Ekman transport) dominates over all mechanisms. However, in the vicinity of capes and coastal features, topographically driven upwelling plays a significant role, and its transports may vary from 43% to 94% of wind-driven upwelling. Upstream of capes, topographically driven vertical motions are downwelling favorable and act against the wind-driven coastal upwelling, while downstream of capes, they are upwelling favorable, where all mechanisms add up to create strong upwelling. Peaks in total upwelling in the CF region are about twice as large as those in the CSM area because the CF region has stronger winds and larger coastline perturbations than in the CSM region. Observed sea surface temperatures (SST) agree well with variability in the vertical transports where upwelling peaks are in phase with low temperature peaks along the coast. Results suggest that on larger scales, the SST variability along the coast is mainly controlled by wind-driven upwelling, while upwelling due to flow-topography interaction is responsible for the smaller scale SST variability.

  2. Cultural Diffusion Was the Main Driving Mechanism of the Neolithic Transition in Southern Africa

    OpenAIRE

    Jerardino, Antonieta; Fort, Joaquim; Isern, Neus; Rondelli, Bernardo

    2014-01-01

    It is well known that the Neolithic transition spread across Europe at a speed of about 1 km/yr. This result has been previously interpreted as a range expansion of the Neolithic driven mainly by demic diffusion (whereas cultural diffusion played a secondary role). However, a long-standing problem is whether this value (1 km/yr) and its interpretation (mainly demic diffusion) are characteristic only of Europe or universal (i.e. intrinsic features of Neolithic transitions all over the world). ...

  3. An Ekman Transport Mechanism for the Atlantic Multidecadal Oscillation

    Science.gov (United States)

    Pratt, V. R.

    2014-12-01

    Multidecadal global climate since 1850 consists of the expected greenhouse warming and two cycles of a fluctuation commonly associated with the AMO that so far has not been satisfactorily explained. In GC53C-06 at AGUFM13 we compared land and sea temperatures during the global warmings of 1860-1880 and 1910-1940 and inferred that heat flowed sea to land, ruling out aerosol-based external forcings and indicating an internal source such as an instability in the AMOC. Length of day during the past century has varied by ~4 ms inversely with the AMO. Noting that the ocean floor is some five times thinner than the continental crust, we propose here that Earth's rotation regulates heat flux through the ocean floor. One mechanism for this is centrifugal force pulling plates apart, particularly along the Mid-Atlantic Ridge and around the Ring of Fire, increasing flux by an amount that would easily pass unnoticed in the 1930s. Another mechanism, perhaps less strong, is stress from rotational acceleration increasing the thermal conductivity of the young rocks comprising the ocean floor. A difficulty is that the ocean would absorb the fluctuations before reaching the surface. We overcome this difficulty via Ekman transport. This mechanism acts on a 50 m deep layer at the surface to drive it polewards from the ITCZ at 3 cm/sec or 1000 km/yr, orders of magnitude faster than the MOC which therefore cannot interfere. This creates a suction at the ITCZ and a downwards pumping action at 30°. In order to close this cycle there must be a flow equal in volume rate towards the ITCZ at depth. We propose that the heat entering the ocean bottom between 30° S and 30° N enters these two "Ekman cells", which carry it to the surface via the ITCZ. To evaluate feasibility, take the area of the participating 50m surface layer to be 1014 m2, making the volume of the top and bottom layers 1016 m3. Only 1022 J of heat is needed to warm or cool this by 1/3.85 = 0.26 °C. Over the 30 years 1910-1940 or 109seconds, this represents 10 TW of warming, raising Earth's total geothermal release from a cold 40 TW to 50 TW (80 to 100 mW/m2), subsequently declining to today's 45-47 TW, an entirely feasible amount. An additional 10 TW to warm the whole OML is still plausible. If this mechanism is correct, varying LOD would forecast varying AMO several years in advance.

  4. 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.

  5. Main mechanical and thermal problems in the vacuum vessel of the FTU Tokamak machine

    International Nuclear Information System (INIS)

    The FTU Tokamak, in order to reach the expected performance has to operate steadily at high magnetic fields. Its vacuum chamber would undergo very high stresses due to thermal and electromagnetic loads for a large number of shots. In order to assess the feasibility of this component, numerical codes to compute current, magnetic field and temperature distributions and extensive three dimensional finite element stress analysis have been developed. The main results obtained are illustrated

  6. 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

  7. Current Imbalances and Main Adjustment Mechanisms in the European Monetary Union

    OpenAIRE

    Gheorghe Matei; Luiza Apostol

    2013-01-01

    The adoption of the euro as a common currency in 17 of the 27 member states of the European Union was achieved in a process that did not strictly observe the recommendations of the economic theory of an optimal monetary area. The elimination of exchange rates before the establishment of European Monetary Union represented the renunciation of an automatic macroeconomic stabilization mechanism and generated major commercial and financial imbalances between the countries in the Eurozone. The eme...

  8. 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

  9. 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

  10. 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.

  11. 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...

  12. Organophosphate Resistance and its Main Mechanism in Populations of Codling Moth (Lepidoptera: Tortricidae) from Central Chile.

    Science.gov (United States)

    Reyes, Maritza; Barros-Parada, Wilson; Ramírez, Claudio C; Fuentes-Contreras, Eduardo

    2015-02-01

    The codling moth, Cydia pomonella (L.), is the key pest of apple production worldwide. Insecticide resistance has been reported in all producing countries, based on five different mechanisms. Codling moth in Chile has resistance to azinphos-methyl and tebufenozide in post-diapausing larvae. However, there are no studies about the susceptibility of these populations to insecticides from other chemical groups. Therefore, the efficacy of azinphos-methyl, chlorpyrifos-ethyl, esfenvalerate, methoxyfenozide, tebufenozide, and thiacloprid on neonate and post-diapausing larvae from six field populations was investigated, and identified resistance mechanisms in this species were evaluated. Neonate larvae were susceptible to all insecticides studied, but post-diapausing larvae from four populations were resistant to chlorpyrifos, one of them was also resistant to azinphos-methyl, and another one was resistant to tebufenozide. The acetylcholinesterase insensitivity mutation was not detected, and the sodium channel knockdown resistance mutation was present in a low frequency in one population. Detoxifying enzymatic activity of glutathione S-transferases, esterases, and cytochrome P-450 monooxygenases in adults differed among populations, but chlorpyrifos resistance was associated only with a decreased esterase activity as shown by a significant negative correlation between chlorpyrifos mortality and esterase activity. PMID:26470131

  13. 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)

  14. Market Mechanism Design for Profitable On-Demand Transport Services

    OpenAIRE

    Egan, Malcolm; Jakob, Michal

    2015-01-01

    On-demand transport services in the form of dial-a-ride and taxis are crucial parts of the transport infrastructure in all major cities. However, not all on-demand transport services are equal. In particular, not-for-profit dial-a-ride services with coordinated drivers significantly differ from profit-motivated taxi services with uncoordinated drivers. As such, there are two key threads of research for efficient scheduling, routing, and pricing for passengers: dial-a-ride se...

  15. Molecular Mechanisms of Urea Transport in Health and Disease

    OpenAIRE

    KLEIN, JANET D.; Blount, Mitsi A.; Sands, Jeff M.

    2012-01-01

    In the late 1980s, urea permeability measurements produced values that could not be explained by paracellular transport or lipid phase diffusion. The existence of urea transport proteins were thus proposed and less than a decade later, the first urea transporter was cloned. The SLC14A family of urea transporters has two major subgroups, designated SLC14A1 (or UT-B) and Slc14A2 (or UT-A). UT-B and UT-A gene products are glycoproteins located in various extra-renal tissues however, a majority o...

  16. Center for low-gravity fluid mechanics and transport phenomena

    Science.gov (United States)

    Kassoy, D. R.; Sani, R. L.

    1991-01-01

    Research projects in several areas are discussed. Mass transport in vapor phase systems, droplet collisions and coalescence in microgravity, and rapid solidification of undercooled melts are discussed.

  17. Interannual forcing mechanisms of California Current transports II: Mesoscale eddies

    Science.gov (United States)

    Davis, Andrew; Di Lorenzo, Emanuele

    2015-02-01

    Mesoscale eddies exert dominant control of cross-shelf exchanges, yet the forcing dynamics underlying their interannual and decadal variability remain uncertain. Using an ensemble of high-resolution ocean model hindcasts of the central and eastern North Pacific from 1950 to 2010 we diagnose the forcing mechanisms of low-frequency eddy variability in the California Current System (CCS). We quantify eddy activity by developing eddy counts based on closed contours of the Okubo-Weiss parameter and find that the spatial and temporal features of model-derived counts largely reproduce the short AVISO observational record. Comparison of model ensemble members allows us to separate the intrinsic and deterministic fractions of eddy variability in the northern CCS (34.5-50°N) and in the southern CCS (28.5-34.5°N). In the North, a large fraction of low-frequency eddy variability (30% anticyclones, 20% cyclones) is deterministic and shared with satellite observations. We develop a diagnostic model based on indices of the large-scale barotropic and baroclinic states of the CCS which recovers this deterministic variance. This model also strongly correlates with local atmospheric forcing. In contrast to the North, Southern CCS eddy counts exhibit very little deterministic variance, and eddy formation closely resembles a red-noise process. This new understanding of the external forcings of eddy variability allows us to better estimate how climate variability and change impact mesoscale transports in the California Current. The skill of our diagnostic model and its close association with local wind stress curl indicate that local atmospheric forcing is the dominant driver of eddy activity on interannual and decadal time scales north of pt. conception (~33°N).

  18. Transport mechanisms in the outer region of RFX-mod

    International Nuclear Information System (INIS)

    Transport properties of the edge region of RFPs are characterized by complicated mechanisms further entangled by the complex magnetic topology. Recently on RFX-mod (Sonato 2003 Fusion Eng. Des. 66-68 161) the use of an efficient feedback system for MHD control allowed the achievement of an unprecedented plasma current for an RFP, of up to 1.6 MA, with an improvement in the confinement properties. This is accompanied by an amelioration of the magnetic boundary and the observation of different MHD regimes, moving from low current multiple helical regime, to high current quasi-single helical ones. At a low plasma current (Ip ? 300-400 kA) in multiple helicity discharge the plasma parameter profiles at the edge are strongly influenced by the presence of m = 0 islands which flatten the temperature profile and modify substantially both the electric drift flow and the E x B shear. The particle diffusion coefficient and the thermal conductivity ?e in this regime are 10-20 m2 s-1 and 100-200 m2 s-1, respectively. Both temperature and pressure characteristic scale lengths are found to scale favourably with the decrease in the secondary modes achieved through the increase in the plasma current. The same trend is observed for the thermal conductivity, and the recently discovered single helical axis states (Lorenzini et al 2008 Phys. Rev. Lett. 101 025005) exhibit an edge ?e reduced by a factor of up to 40%. Finally the perpendicular flow at the edge is found to scale with the density normalized to the Greenwald density with a saturation at values around n/nG ? 0.35.

  19. Transport mechanisms in the outer region of RFX-mod

    Science.gov (United States)

    Vianello, N.; Martines, E.; Agostini, M.; Alfier, A.; Canton, A.; Cavazzana, R.; DeMasi, G.; Fassina, A.; Lorenzini, R.; Scarin, P.; Serianni, G.; Spagnolo, S.; Spizzo, G.; Spolaore, M.; Zuin, M.; RFX-mod Team

    2009-04-01

    Transport properties of the edge region of RFPs are characterized by complicated mechanisms further entangled by the complex magnetic topology. Recently on RFX-mod (Sonato 2003 Fusion Eng. Des. 66-68 161) the use of an efficient feedback system for MHD control allowed the achievement of an unprecedented plasma current for an RFP, of up to 1.6 MA, with an improvement in the confinement properties. This is accompanied by an amelioration of the magnetic boundary and the observation of different MHD regimes, moving from low current multiple helical regime, to high current quasi-single helical ones. At a low plasma current (Ip ? 300-400 kA) in multiple helicity discharge the plasma parameter profiles at the edge are strongly influenced by the presence of m = 0 islands which flatten the temperature profile and modify substantially both the electric drift flow and the E × B shear. The particle diffusion coefficient and the thermal conductivity ?e in this regime are 10-20 m2 s-1 and 100-200 m2 s-1, respectively. Both temperature and pressure characteristic scale lengths are found to scale favourably with the decrease in the secondary modes achieved through the increase in the plasma current. The same trend is observed for the thermal conductivity, and the recently discovered single helical axis states (Lorenzini et al 2008 Phys. Rev. Lett. 101 025005) exhibit an edge ?e reduced by a factor of up to 40%. Finally the perpendicular flow at the edge is found to scale with the density normalized to the Greenwald density with a saturation at values around n/nG ? 0.35.

  20. Differential mechanisms for insulin-induced relaxations in mouse posterior tibial arteries and main mesenteric arteries.

    Science.gov (United States)

    Qu, Dan; Liu, Jian; Lau, Chi Wai; Huang, Yu

    2014-12-01

    The characteristics of endothelium-dependent relaxations in response to insulin and acetylcholine (ACh) in the mouse posterior tibial artery (PTA) were studied on wire myograph, and compared to those in the mouse main mesenteric artery (MMA). Insulin-induced relaxation in PTA was reversed by PI3K and Akt inhibitors, LY294002 and triciribine, but not by nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME) or guanylate cyclase inhibitor, ODQ. The relaxation in PTA was also inhibited by apamin (small-conductance Ca(2+)-activated K(+) channel blocker) plus charybdotoxin (intermediate-conductance Ca(2+)-activated K(+) channel blocker), elevated KCl or ouabain (Na(+)-K(+) ATPase inhibitor) plus BaCl(2) [inwardly rectifying K(+) (K(IR)) channel inhibitor]; whereas L-NAME but not triciribine inhibited ACh-induced relaxation in PTA. On the other hand, nitric oxide and endothelium-derived hyperpolarizing factor albeit to a less extent mediated both insulin- and ACh-induced relaxations in MMA. The present study is for the first time dissecting out the components of endothelium-dependent relaxation in mouse PTA and suggesting differential responses to different agonists in distinctive blood vessels. PMID:25446161

  1. Current Imbalances and Main Adjustment Mechanisms in the European Monetary Union

    Directory of Open Access Journals (Sweden)

    Gheorghe Matei

    2013-11-01

    Full Text Available The adoption of the euro as a common currency in 17 of the 27 member states of the European Union was achieved in a process that did not strictly observe the recommendations of the economic theory of an optimal monetary area. The elimination of exchange rates before the establishment of European Monetary Union represented the renunciation of an automatic macroeconomic stabilization mechanism and generated major commercial and financial imbalances between the countries in the Eurozone. The emergence of the financial crisis in 2008 combined with the lack of mobility of the labor at European level and the lack of fiscal reforms in the less competitive countries led to the current situation of the unsustainable public debts. The measures envisaged with the purpose to address this crisis are different in terms of level of assistance the competitive countries have to give to the others, the duration and value of wealth transfers that should be made between the states and the limit from which they will affect the fundamental stability and prosperity policy objectives of the European project.

  2. Mechanism of strain retention and shape memory in main chain liquid crystalline networks

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Wanting; Griffin, Anselm C. [School of Materials Science and Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, GA 30332-0295 (United States)

    2012-07-15

    Liquid crystalline networks (LCNs) are described in which there is anelasticity in strain recovery response (under zero load) after uniaxial tensile loading. This strain retention is shown as a function of time after release of load and is further characterized by thermal, X-ray, and stress/strain experiments. It was found that, at temperatures in the smectic phase far below the isotropization temperature, this LCN film retains significant levels of strain when in the monodomain state. On free recovery (zero load) of the LCN film there is a rapid elastic response followed by a slow anelastic response for those films that had undergone a polydomain-to-monodomain transition during the initial imposed strain regimen. It is postulated that the mechanism leading to the strain retention involves nanosegregation-driven pinning of unfolded hairpins in shallow energy wells and that this effect is responsible for the thermally activated recovery of strain (shape memory) at elevated temperatures. Stress-strain curves of pre-strained C11(MeHQ)Si8XL10 LC networks having various initial strains: (a) 350%, (b) 300%, (c) 250%, (d) 200%, (e) 150%, (f) 100%, and (g) 50%. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. On-Chip Transportation and Measurement of Mechanical Characteristics of Oocytes in an Open Environment

    Directory of Open Access Journals (Sweden)

    Kou Nakahara

    2015-05-01

    Full Text Available We propose a system that transports oocytes and measures their mechanical characteristics in an open environment using a robot integrated microfluidic chip (chip. The cells are transported through a micropillar array in the chip, and their characteristics are measured by a mechanical probe and a force sensor. Because the chip has an open microchannel, important cells such as oocytes are easily introduced and collected without the risk for losing them. In addition, any bubbles trapped in the chip, which degrade the measurement precision, are easily removed. To transport the oocytes through the open microchannel, we adopt a transportation technique based on a vibration-induced flow. Under this flow, oocytes arrive at the measurement point, where their mechanical characteristics are determined. We demonstrate the introduction, transportation, measurement of mechanical characteristics, and collection of oocytes using this system.

  4. From Phenix to Super Phenix: mechanical structures assuring reactor vessel tightness at main sodium pump penetrations

    International Nuclear Information System (INIS)

    Even though the components of SUPER PHENIX are larger than those of PHENIX, there is no corresponding increase in available vessel height. Furthermore the SUPER PHENIX vessel does not possess a roof. For these reasons, original and patented solutions, which, nevertheless, take advantage of the experimental results and operating experience acquired with PHENIX, were sought. The most important parameters are: weights and sizes of various components; stresses transmitted to the structures differential displacements between the top and bottom positions of components; inclinations due to deformation of the deck; preservation of containment at places where components penetrate the deck. In the solution finally adopted, an elastic torus shaped ring, which forms a ball-and-socket type joint is used. A thin shell structure connects the bottom to the reactor internals in such a way as to permit both vertical and rotational displacements. The upper joint consists of: a bolted double flange system; flanged component; a torus with a gear tooth shape profile made of elastic material; leaktight bellows attached to both flanges. Studies and calculations have been completed with the realization of a 1/5 scale model of the upper torus ring. Displacement, and angular and axial stiffness measurements have confirmed the validity of the hypotheses. Moreover, even though the lower part is an extrapolation of PHENIX, full scale experimental tests have been carried out in sodium, reproducing the real displacements and forces that will be experienced in the reactor. Finally, the pumps will be tested with water; the suspension will be studied (investigation of relevant mechanical parameters, measurement of leaktightness with respect to the outside)

  5. 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.

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

    Scientific Electronic Library Online (English)

    R, Millaleo; M, Reyes- Diaz; A.G, Ivanov; M.L, Mora; M, Alberdi.

    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, an [...] d 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 organdíes 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.

  7. Mimicking cellular transport mechanism in stem cells through endosomal escape of new peptide-coated quantum dots

    OpenAIRE

    Narayanan, Karthikeyan; Yen, Swee Kuan; Dou, Qingqing; Padmanabhan, Parasuraman; Sudhaharan, Thankiah; Ahmed, Sohail; Ying, Jackie Y.; Selvan, Subramanian Tamil

    2013-01-01

    Protein transport is an important phenomenon in biological systems. Proteins are transported via several mechanisms to reach their destined compartment of cell for its complete function. One such mechanism is the microtubule mediated protein transport. Up to now, there are no reports on synthetic systems mimicking the biological protein transport mechanism. Here we report a highly efficient method of mimicking the microtubule mediated protein transport using newly designed biotinylated peptid...

  8. 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)

  9. Basic mechanisms for recognition and transport of synaptic cargos

    OpenAIRE

    Schlager Max A; Hoogenraad Casper C

    2009-01-01

    Abstract Synaptic cargo trafficking is essential for synapse formation, function and plasticity. In order to transport synaptic cargo, such as synaptic vesicle precursors, mitochondria, neurotransmitter receptors and signaling proteins to their site of action, neurons make use of molecular motor proteins. These motors operate on the microtubule and actin cytoskeleton and are highly regulated so that different cargos can be transported to distinct synaptic specializations at both pre- and post...

  10. 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.

  11. Evaluation of hydrazine as an additive to provide reducing condition in the main heat transport system of AHWR

    International Nuclear Information System (INIS)

    Hydrogen is known to be injected in boiling water reactors to mitigate stress corrosion cracking (SCC) due to the oxidizing environment prevailing in the reactor coolant system. Further this technique has been modified by addition of noble metals such as Pt, Ir so that the required ECP can be achieved by injecting a lower concentration of hydrogen. All the boiling water reactors are pot type reactors. Unlike BWRs, the Advanced Heavy Water Reactor (AHWR) is a boiling tube type reactor. Here, boiling takes place in the tube and the coolant exits the core with 18 % steam. The steam containing water exits the core through tail pipes connected to each fuel channel. The material of construction of most of the AHWR main coolant system components is stainless steel. Hence, the possibility of stress corrosion cracking of stainless steel components can not be ruled out if oxidizing chemistry conditions prevail in the coolant. Addition of hydrogen and hydrogen with noble metal may not be effective in controlling the radiolytic generation of oxygen/hydrogen peroxide under the two phase conditions prevailing in the fuel channels (tubes) of the core. Hence, the feasibility of using hydrazine to provide reducing condition to the main heat transport system of AHWR was studied. Computation on the generation of oxidizing species (O2 and H2O2) and their distribution in steam and water phase were made. The difference in the distribution behavior of hydrogen and hydrazine under AHWR condition is explained in the paper. Analytical methods have been standardized to study the distribution of hydrazine, ammonia, oxygen and hydrogen peroxide and tested by carrying out radiolysis of water containing hydrazine etc. Experiments were also carried out in the High Temperature and High Pressure (HTHP) system at WSCD to study the thermal stability of hydrazine and to evaluate its effect on the redox potential and corrosion potential of stainless steel under the simulated AHWR temperature conditions. The effect of hydrazine concentration and temperature on the electrochemical corrosion potentials (ECP) and redox was monitored. Thermal stability of hydrazine was studied over a wide range of temperature. Redox potential changed from -0.4 V versus the standard hydrogen electrode (V(SHE)) to -0.67 V(SHE) on addition of 5 ppm of hydrazine at 240 deg C. The decomposition rate of hydrazine was observed to follow a first order decay at 240 deg C where as a mixed rate was observed at 200 deg C. (author)

  12. LOS COMIENZOS DEL TRANSPORTE MECANIZADO TERRESTRE EN MAGALLANES (1900-1930) / THE BEGINNINGS OF MECHANIZED TERRESTRIAL TRANSPORT IN MAGELLAN (1900-1930)

    Scientific Electronic Library Online (English)

    Mateo, Martinic B.

    2009-07-01

    Full Text Available Se da cuenta de las formas y circunstancias que determinaron la evolución del sistema de transporte en Magallanes, desde los carruajes de tiro animal propios de la época de la colonización inicial, hasta los vehículos automotores, fenómeno entendido como la culminación del ciclo de modernización mec [...] ánica que caracterizó a la crianza ovejera extensiva, que fue la actividad vertebradora matriz de la economía magallánica. Abstract in english The forms and circumstances that determined the evolution of transport systems in Magellan are narrated, from the carriages pushed by animal’s characteristic of the initial settling epoch, up to the self-propelled vehicles, phenomenon understood as the culmination of the cycle of mechanical moderniz [...] ation that characterized the upbringing extensive sheep farming, main vertebrate activity of the magellanic economy.

  13. Mechanisms Underlying the Antinociceptive, Antiedematogenic, and Anti-Inflammatory Activity of the Main Flavonoid from Kalanchoe pinnata

    OpenAIRE

    Ferreira, Raquel Teixeira; Coutinho, Marcela Araújo Soares; Malvar, David do Carmo; Costa, Elson Alves; Florentino, Iziara Ferreira; Costa, Sônia Soares; Vanderlinde, Frederico Argollo

    2014-01-01

    Kalanchoe pinnata (KP) is popularly used for treating inflammatory diseases. This study investigated the antinociceptive, antiedematogenic, and anti-inflammatory potential of the subcutaneous administration of KP flower aqueous extract (KPFE), its ethyl acetate (EtOAcF) and butanol (BuOHF) fractions, and the main KP flavonoid [quercetin 3-O-?-L-arabinopyranosyl (1 ? 2) ?-L-rhamnopyranoside] (KPFV) in mice, as well as its possible mechanisms of action. KPFE (30–300?mg/kg) and KPFV (1–10?mg/kg)...

  14. Osmotic water transport in aquaporins : evidence for a stochastic mechanism

    DEFF Research Database (Denmark)

    Zeuthen, Thomas; Alsterfjord, Magnus

    2013-01-01

    Abstract? We test a novel, stochastic model of osmotic water transport in aquaporins. A solute molecule present at the pore mouth can either be reflected or permeate the pore. We assume that only reflected solute molecules induce osmotic transport of water through the pore, while permeating solute molecules give rise to no water transport. Accordingly, the rate of water transport is proportional to the reflection coefficient ?, while the solute permeability, P(S), is proportional to 1 - ?. The model was tested in aquaporins heterologously expressed in Xenopus oocytes. A variety of aquaporin channel sizes and geometries were obtained with the two aquaporins AQP1 and AQP9 and mutant versions of these. Osmotic water transport was generated by adding 20 mM of a range of different-sized osmolytes to the outer solution. The osmotic water permeability and the reflection coefficient were measured optically at high resolution and compared to the solute permeability obtained from short-term uptake of radio-labelled solute under isotonic conditions. For each type of aquaporin there was a linear relationship between solute permeability and reflection coefficient, in accordance with the model. We found no evidence for coupling between water and solute fluxes in the pore. In confirmation of molecular dynamic simulations, we conclude that the magnitude of the osmotic water permeability and the reflection coefficient are determined by processes at the arginine selectivity filter located at the outward-facing end of the pore.

  15. 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...

  16. Water transport mechanism through open capillaries analyzed by direct surface modifications on biological surfaces

    OpenAIRE

    Ishii, Daisuke; Horiguchi, Hiroko; Hirai, Yuji; Yabu, Hiroshi; Matsuo, Yasutaka; Ijiro, Kuniharu; Tsujii, Kaoru; Shimozawa, Tateo; Hariyama, Takahiko; Shimomura, Masatsugu

    2013-01-01

    Some small animals only use water transport mechanisms passively driven by surface energies. However, little is known about passive water transport mechanisms because it is difficult to measure the wettability of microstructures in small areas and determine the chemistry of biological surfaces. Herein, we developed to directly analyse the structural effects of wettability of chemically modified biological surfaces by using a nanoliter volume water droplet and a hi-speed video system. The whar...

  17. Electron transport mechanisms in thin boron-doped diamond films

    International Nuclear Information System (INIS)

    Electron transmission spectroscopy is used to examine the effect of transport distance, diamond nanostructure, and electron affinity on the cold emission characteristics of thin nanocrystalline diamond films. Energy distribution and intensity measurements are taken from films having different thicknesses (?0.15, 2, and 4 ?m) and surface properties (hydrogenated, cesiated), and two distinct transmission regimes are identified that exhibit fundamentally different characteristics. In measurements taken at sufficiently high beam energy Eo, electrons are transported through the conduction band of the diamond and emitted at a low-affinity surface, with transmission yields generally greater than 1. In this regime, the dependence on Eo results from the finite escape depth of the conduction-band electrons, which is determined to be ?1 ?m for these films based on a Monte Carlo analysis of the incident electron range. In measurements taken at lower values of Eo, electrons are generated outside of this escape range and are unable to reach the surface via conduction-band transport. In this regime, the transmission data are dominated by a much broader, low-intensity distribution, and the transmission yields are substantially lower than 1. The transmission is furthermore completely insensitive to changes in the surface properties of the diamond. Based on the nanostructure of the films, electrons are most likely transported along grain boundaries that propagate through the films

  18. Endoplasmic reticulum: Where nucleotide sugar transport meets cytokinin control mechanisms.

    Science.gov (United States)

    Niemann, Michael Ce; Werner, Tomáš

    2015-10-01

    The endoplasmic reticulum (ER) is a multifunctional eukaryotic organelle where the vast majority of secretory proteins are folded and assembled to achieve their correct tertiary structures. The lumen of the ER and Golgi apparatus also provides an environment for numerous glycosylation reactions essential for modifications of proteins and lipids, and for cell wall biosynthesis. These glycosylation reactions require a constant supply of cytosolically synthesized substrate precursors, nucleotide sugars, which are transported by a group of dedicated nucleotide sugar transporters (NST). Recently, we have reported on the identification of a novel ER-localized NST protein, ROCK1, which mediates the transport of UDP-linked acetylated hexosamines across the ER membrane in Arabidopsis. Interestingly, it has been demonstrated that the activity of ROCK1 is important for the regulation of cytokinin-degrading enzymes, cytokinin oxidases/dehydrogenases (CKX), in the ER and, thus, for cytokinin responses. In this addendum we will address the biochemical and cellular activity of the ROCK1 transporter and its phylogenetic relation to other NST proteins. PMID:26418963

  19. 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).

  20. Mechanisms of acetylcholine synthesis: Coupling with choline transport

    International Nuclear Information System (INIS)

    Comparative studies were performed to assess the utilization of choline transported by synaptosomal sodium-dependent, high-affinity choline carriers for the synthesis of ACh; it was determined that a significantly higher percentage of tritium-choline transported into rat forebrain synaptosomes was acetylated immediately compared to that of guinea-pig. Studies were performed to determine whether inhibition of synaptosomal ChAT was produced by incubating guinea-pig brain synaptosomes with ChMAz, comparable to that observed with rat brain synaptosomes. Very little ChAT activity was measured in guinea-pig brain; that this difference could reflect differing subcellular localizations of ChAT and different relativities with respect to coupling with choline carriers is speculative and currtly being investigated

  1. Relative mechanical quantities in spaces with a transport along paths

    CERN Document Server

    Iliev, Bozhidar Z

    1994-01-01

    The concepts of relative velocity and acceleration, deviation velocity and acceleration and relative momentum of point particles in spaces (manifolds), the tangent bundle of which is equipped with a transport along paths, are introduced. If the tangent bundle is endowed also with a metric, it gives rise also to the notion of a relative energy. Certain ties between these quantities are considered. The cases of massless particles and of special relativity are presented in this context.

  2. Relative mechanical quantities in spaces with a transport along paths

    OpenAIRE

    Iliev, Bozhidar Z.

    2003-01-01

    The concepts of relative velocity and acceleration, deviation velocity and acceleration and relative momentum of point particles in spaces (manifolds), the tangent bundle of which is equipped with a transport along paths, are introduced. If the tangent bundle is endowed also with a metric, it gives rise also to the notion of a relative energy. Certain ties between these quantities are considered. The cases of massless particles and of special relativity are presented in this...

  3. Identification of a Novel System for Boron Transport: Atr1 Is a Main Boron Exporter in Yeast? †

    OpenAIRE

    Kaya, Alaattin; Karakaya, Huseyin C.; Fomenko, Dmitri E; GLADYSHEV, Vadim N.; Koc, Ahmet

    2009-01-01

    Boron is a micronutrient in plants and animals, but its specific roles in cellular processes are not known. To understand boron transport and functions, we screened a yeast genomic DNA library for genes that confer resistance to the element in Saccharomyces cerevisiae. Thirty boron-resistant transformants were isolated, and they all contained the ATR1 (YML116w) gene. Atr1 is a multidrug resistance transport protein belonging to the major facilitator superfamily. C-terminal green fluorescent p...

  4. Modeling Transport and Flow Regulatory Mechanisms of the Kidney

    OpenAIRE

    Layton, Anita T.

    2012-01-01

    The kidney plays an indispensable role in the regulation of whole-organism water balance, electrolyte balance, and acid-base balance, and in the excretion of metabolic wastes and toxins. In this paper, we review representative mathematical models that have been developed to better understand kidney physiology and pathophysiology, including the regulation of glomerular filtration, the regulation of renal blood flow by means of the tubuloglomerular feedback mechanisms and of the myogenic mechan...

  5. Molecular parameters and transmembrane transport mechanism of imidazolium-functionalized binols.

    Science.gov (United States)

    Vidal, Marc; Schmitzer, Andreea

    2014-08-01

    We describe the molecular parameters governing the transmembrane activity of imidazolium-functionalized anion transporters and present a detailed mechanistic study. These ionophores adopt a mobile-carrier mechanism for short methyl and butyl chains, a combined mobile-carrier/transmembrane-pore mechanism for octyl and dodecyl chains, and form transmembrane aggregates for hexadecyl chains. PMID:25043746

  6. Chronic exposure to cereal mycotoxin likely citreoviridin may be a trigger for Keshan disease mainly through oxidative stress mechanism.

    Science.gov (United States)

    Sun, Shuqiu

    2010-05-01

    The origin of Keshan disease (KD), an endemic cardiomyopathy particularly affected children and young women in China, has been a controversial and difficult problem in academics over the past decades. We hypothesize that mycotoxins likely citreoviridin may initiate KD mainly through oxidative stress mechanism by long-term consumption of mouldy cereals due to food shortage lifestyle. Dietary deficiency of selenium, proteins, Vitamin C, E, etc., may act as enhancing factors to exacerbate the pathological damage. This speculation can perfectly explain the features of KD and has received strong supporting evidences. If the hypothesis were to be confirmed, it is of very important value in monitoring and blocking the incidence of KD. Thus, future efforts are needed to investigate specific biomarkers of exposure to citreoviridin in KD cases. PMID:20034747

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

    Science.gov (United States)

    Alvarino, T; Suarez, S; Lema, J M; Omil, F

    2014-08-15

    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. PMID:25010455

  8. Turbulence elasticity—A 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); Gürcan, Ö. 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 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?{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.

  9. 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.

  10. Lamination in Atmospheric Ozone: A Diagnostic for Tracer Transport Mechanisms

    Science.gov (United States)

    Minschwaner, Kenneth; Manney, Gloria; Torres, Luis

    2015-03-01

    An understanding of ozone variability in the upper troposphere (from ~5 km altitude up to the tropopause level) is critical to assessing the radiative forcing of climate by ozone, and for evaluating the impact of transport on regional air quality. Part of this variability arises in fine-layered (~0.2 to ~2 km) structures seen in vertical profile measurements of ozone. These laminae are also generally limited on horizontal scales (10's to 100's of km), leading to spatial ozone variability observed on quasi-horizontal coordinate surfaces. Given the relatively long photochemical time constants for ozone in the upper troposphere, most of the observed variability arises from transport rather than photochemistry. There are a wide range of dynamical processes that can generate ozone laminae in the upper troposphere, such as gravity and Rossby waves, convective lofting and detrainment of either high or low ozone amounts from the boundary layer, and intrusions of air masses with high ozone concentrations from the stratosphere. Here, we examine the range of observed laminae characteristics and describe methods for tracing the origins of tropospheric ozone laminae.

  11. 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

  12. 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.

  13. Identification of regulatory mechanisms of intestinal folate transport in condition of folate deficiency.

    Science.gov (United States)

    Thakur, Shilpa; Rahat, Beenish; Hamid, Abid; Najar, Rauf Ahmad; Kaur, Jyotdeep

    2015-10-01

    Folic acid is an essential micronutrient, deficiency of which can lead to disturbance in various metabolic processes of cell. Folate transport across intestine occurs via the involvement of specialized folate transporters viz. proton coupled folate transporter (PCFT) and reduced folate carrier (RFC), which express at the membrane surfaces. The current study was designed to identify the regulatory mechanisms underlying the effects of folate deficiency (FD) on folate transport in human intestinal cell line as well as in rats and to check the reversibility of such effects. Caco-2 cells were grown for five generations in control and FD medium. Following treatment, one subgroup of cells was shifted on folate sufficient medium and grown for three more generations. Similarly, rats were fed an FD diet for 3 and 5 months, and after 3 months of FD treatment, one group of rats were shifted on normal folate-containing diet. Increase in folate transport and expression of folate transporters were observed on FD treatment. However, when cells and rats were shifted to control conditions after treatment, transport and expression of these genes restored to the control level. FD was found to have no impact on promoter methylation of PCFT and RFC; however, messenger RNA stability of transporters was found to be decreased, suggesting some adaptive response. Overall, increased expression of transporters under FD conditions can be attributed to enhanced rate of transcription of folate transporters and also to the increased binding of specificity protein 1 transcription factor to the RFC promoter only. PMID:26168702

  14. Transport of Heat and Charge in Electromagnetic Metrology Based on Nonequilibrium Statistical Mechanics

    Directory of Open Access Journals (Sweden)

    James Baker-Jarvis

    2009-11-01

    Full Text Available Current research is probing transport on ever smaller scales. Modeling of the electromagnetic interaction with nanoparticles or small collections of dipoles and its associated energy transport and nonequilibrium characteristics requires a detailed understanding of transport properties. The goal of this paper is to use a nonequilibrium statistical-mechanical method to obtain exact time-correlation functions, fluctuation-dissipation theorems (FD, heat and charge transport, and associated transport expressions under electromagnetic driving. We extend the time-symmetric Robertson statistical-mechanical theory to study the exact time evolution of relevant variables and entropy rate in the electromagnetic interaction with materials. In this exact statistical-mechanical theory, a generalized canonical density is used to define an entropy in terms of a set of relevant variables and associated Lagrange multipliers. Then the entropy production rate are defined through the relevant variables. The influence of the nonrelevant variables enter the equations through the projection-like operator and thereby influences the entropy. We present applications to the response functions for the electrical and thermal conductivity, specific heat, generalized temperature, Boltzmann’s constant, and noise. The analysis can be performed either classically or quantum-mechanically, and there are only a few modifications in transferring between the approaches. As an application we study the energy, generalized temperature, and charge transport equations that are valid in nonequilibrium and relate it to heat flow and temperature relations in equilibrium states.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-01-01

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

  16. 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.

  17. Structure and permeation mechanism of a mammalian urea transporter

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Elena J.; Cao, Yu; Enkavi, Giray; Quick, Matthias; Pan, Yaping; Tajkhorshid, Emad; Zhou, Ming (UIUC); (Columbia)

    2012-09-17

    As an adaptation to infrequent access to water, terrestrial mammals produce urine that is hyperosmotic to plasma. To prevent osmotic diuresis by the large quantity of urea generated by protein catabolism, the kidney epithelia contain facilitative urea transporters (UTs) that allow rapid equilibration between the urinary space and the hyperosmotic interstitium. Here we report the first X-ray crystal structure of a mammalian UT, UT-B, at a resolution of 2.36 {angstrom}. UT-B is a homotrimer and each protomer contains a urea conduction pore with a narrow selectivity filter. Structural analyses and molecular dynamics simulations showed that the selectivity filter has two urea binding sites separated by an approximately 5.0 kcal/mol energy barrier. Functional studies showed that the rate of urea conduction in UT-B is increased by hypoosmotic stress, and that the site of osmoregulation coincides with the location of the energy barrier.

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

    OpenAIRE

    Sarah Spreckelmeyer; Chris Orvig; Angela Casini

    2014-01-01

    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 activ...

  19. Effect of Temperature on Thermal Transport and Mechanical Properties of Trans-polyisoprene

    Science.gov (United States)

    Baboo, Mahesh; Dixit, Manasvi; Sharma, Kananbala; Saxena, N. S.

    2010-06-01

    Thick and thin films of trans-polyisoprene (TPI) have been prepared using solution casting method by dissolving TPI in toluene. Thick films of TPI have been used to determine thermal transport properties at different temperatures through Thermal Constant Analyzer (TCA). The results show that thermal conductivity, thermal diffusivity and volumetric heat capacity increase with respect to temperature. Thin films of TPI on the other hand have been utilized for the measurement of mechanical properties such as Young's modulus, tensile strength and toughness. The effect of temperature on the mechanical properties of thin films of TPI has been investigated using Dynamic Mechanical analyzer (DMA) and it was found that the mechanical properties decrease with increasing temperature. Above said behavior of the thermal transport and mechanical properties as a function of temperatures is attributed to the increase in free volume of molecules in chains with temperature.

  20. Effects of intravenous furosemide on mucociliary transport and rheological properties of patients under mechanical ventilation

    OpenAIRE

    Kondo, Cláudia Seiko; Macchionne, Mariângela; Nakagawa, Naomi Kondo; Carvalho, Carlos Roberto Ribeiro; King, Malcolm; Saldiva, Paulo Hilário Nascimento; Lorenzi-Filho, Geraldo

    2001-01-01

    The use of intravenous (IV) furosemide is common practice in patients under mechanical ventilation (MV), but its effects on respiratory mucus are largely unknown. Furosemide can affect respiratory mucus either directly through inhibition of the NaK(Cl)2 co-transporter on the basolateral surface of airway epithelium or indirectly through increased diuresis and dehydration. We investigated the physical properties and transportability of respiratory mucus obtained from 26 patients under MV distr...

  1. In Vivo Imaging of oskar mRNA Transport Reveals the Mechanism of Posterior Localization

    OpenAIRE

    Zimyanin, VL; Belaya, K; Pecreaux, J; Gilchrist, MJ; Clark, A.; Davis, I; St. Johnston, D.

    2008-01-01

    oskar mRNA localization to the posterior of the Drosophila oocyte defines where the abdomen and germ cells form in the embryo. Although this localization requires microtubules and the plus end-directed motor, kinesin, its mechanism is controversial and has been proposed to involve active transport to the posterior, diffusion and trapping, or exclusion from the anterior and lateral cortex. By following oskar mRNA particles in living oocytes, we show that the mRNA is actively transported along ...

  2. 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.; C. J. van Duijn

    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 ...

  3. D-cycloserine uses an active transport mechanism in the human intestinal cell line Caco 2.

    OpenAIRE

    Ranaldi, G; Islam, K.; Sambuy, Y

    1994-01-01

    In a previous study we have shown that cultured epithelial cell lines can be used to measure the transepithelial passage of antimicrobial agents across the intestine and to obtain information on the mechanisms of transport utilized and predict the bioavailability of the antimicrobial agents after oral administration. In particular, among the drugs investigated, D-cycloserine had been shown to be transported in a polarized manner only in the intestinal cells. In the present work, further chara...

  4. 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.

  5. Mechanisms Underlying the Antinociceptive, Antiedematogenic, and Anti-Inflammatory Activity of the Main Flavonoid from Kalanchoe pinnata.

    Science.gov (United States)

    Ferreira, Raquel Teixeira; Coutinho, Marcela Araújo Soares; Malvar, David do Carmo; Costa, Elson Alves; Florentino, Iziara Ferreira; Costa, Sônia Soares; Vanderlinde, Frederico Argollo

    2014-01-01

    Kalanchoe pinnata (KP) is popularly used for treating inflammatory diseases. This study investigated the antinociceptive, antiedematogenic, and anti-inflammatory potential of the subcutaneous administration of KP flower aqueous extract (KPFE), its ethyl acetate (EtOAcF) and butanol (BuOHF) fractions, and the main KP flavonoid [quercetin 3-O-?-L-arabinopyranosyl (1 ? 2) ?-L-rhamnopyranoside] (KPFV) in mice, as well as its possible mechanisms of action. KPFE (30-300?mg/kg) and KPFV (1-10?mg/kg) inhibited the acetic acid-induced writhing (ID50 = 164.8 and 9.4?mg/kg, resp.). KPFE (300?mg/kg), EtOAcF (12?mg/kg), BuOHF (15?mg/kg), or KPFV (0.3-3.0?mg/kg) reduced leukocyte migration on carrageenan-induced pleurisy (ID50 = 2.0?mg/kg for KPFV). KPFE (3-30?mg/kg) and KPFV (0.3-3.0?mg/kg) reduced the croton oil-induced ear edema (ID50 = 4.3 and 0.76?mg/kg, resp.). KPFE and KPFV reduced the TNF-? concentration in the pleural exudates on carrageenan-induced pleurisy test. Moreover, KPFV inhibited COX-1 (IC50 = 22.1??g/mL) and COX-2 (IC50 > 50??g/mL). The selectivity index (COX-1IC50 /COX-2IC50 ) was <0.44. These results indicate that KPFE and KPFV produced antinociceptive, antiedematogenic, and anti-inflammatory activities through COX inhibition and TNF-? reduction, revealing that the main flavonoid in KP flowers and leaves plays an important role in the ethnomedicinal use of the plant. PMID:25580151

  6. 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.)

  7. Regional variation of the dimethyl sulfide oxidation mechanism in the summertime marine boundary layer in the Gulf of Maine

    Science.gov (United States)

    Osthoff, Hans D.; Bates, Timothy S.; Johnson, James E.; Kuster, William C.; Goldan, Paul; Sommariva, Roberto; Williams, Eric J.; Lerner, Brian M.; Warneke, Carsten; de Gouw, Joost A.; Pettersson, Anders; Baynard, Tahllee; Meagher, James F.; Fehsenfeld, Frederick C.; Ravishankara, A. R.; Brown, Steven S.

    2009-04-01

    Mixing ratios of dimethyl sulfide (DMS) and its nighttime oxidant, the nitrate radical (NO3), were measured in the summertime marine boundary layer (MBL) of the Gulf of Maine during the New England Air Quality Study-International Transport and Chemical Transformation campaign in 2004. DMS fluxes from the ocean were derived from simultaneous measurements of the wind speed and DMS in seawater. Day and night DMS oxidation rates were determined from modeled OH and measured NO3 concentrations. The average DMS lifetime with respect to oxidation by OH at noon was 13.5 ± 3.4 (1?) h, while at night, DMS lifetimes with respect to NO3 oxidation varied by sampling region from 11 min to 28 h. Oxidation by photochemically generated halogen species likely also played a role during the day, although the nature and extent of the halogen species is more difficult to predict due to lack of halogen measurements. Closure of the DMS budget in the MBL required a vertical entrainment velocity of ˜0.4 cm s-1. This study suggests that entrainment of DMS out of the MBL competes with daytime oxidation and that the presence of pollution in the form of NOx and O3 in near-coastal regions at night results in nearly complete DMS oxidation within the MBL via reaction with NO3, with a much smaller contribution from entrainment. One potential implication of near-complete DMS oxidation within the MBL is a reduction of the amount of sulfur available for aerosol formation and growth at higher altitudes in the atmosphere.

  8. 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

  9. The homodimeric ATP-binding cassette transporter LmrA mediates multidrug transport by an alternating two-site (two-cylinder engine) mechanism

    OpenAIRE

    Van Veen, Hendrik W.; Margolles, Abelardo; Müller, Michael; Higgins, Christopher F.; Wil N. Konings

    2000-01-01

    The bacterial LmrA protein and the mammalian multidrug resistance P-glycoprotein are closely related ATP-binding cassette (ABC) transporters that confer multidrug resistance on cells by mediating the extrusion of drugs at the expense of ATP hydrolysis. The mechanisms by which transport is mediated, and by which ATP hydrolysis is coupled to drug transport, are not known. Based on equilibrium binding experiments, photoaffinity labeling and drug transport assays, we conclude that homodimeric Lmr...

  10. The fluid mechanics of nutrient transport within biofilms

    Science.gov (United States)

    Brenner, Michael; Seminara, Agnese; Sinha, Naveen; Wilking, James; Angelini, Tommy; Kolter, Roberto; Weitz, David

    2011-11-01

    Bacterial biofilms are interface-associated colonies of bacteria embedded in an extracellular matrix that is composed primarily of polymers and proteins. During the growth of a biofilm, nutrient is taken up by the surface of the biofilm, and contained by cells in the bulk. A critical problem is that above a critical size there is necessarily a growth bottleneck, in which the biofilm cannot take up enough nutrients to feed all of the cells within it. We discuss, through theory and experiments, several strategies that are employed by biofilms of Bacillus subtilus to avoid this growth bottleneck. These include clever use and control of osmotic pressure (through the expression of polymeric extracellular matrix); the excretion of surfactants and the use of associated marangoni stresses; and the distribution of flagella (used as mixers) within the bulk of the biofilm. Some speculations about other potential mechanisms (for which there is no current experimental support) will also be presented.

  11. 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

  12. 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.

  13. Fluorescence measurement of chloride transport in monolayer cultured cells. Mechanisms of chloride transport in fibroblasts.

    OpenAIRE

    Chao, A. C.; Dix, J A; Sellers, M. C.; VERKMAN, A. S.

    1989-01-01

    The methodology has been developed to measure Cl activity and transport in cultured cells grown on a monolayer using the entrapped Cl-sensitive fluorophore 6-methoxy-N-[3-sulfopropyl] quinolinium (SPQ). The method was applied to a renal epithelial cell line, LLC-PKI, and a nonepithelial cell line, Swiss 3T3 fibroblasts. SPQ was nontoxic to cells when present for greater than h in the culture media. To load with SPQ (5 mM), cells were made transiently permeable by exposure to hypotonic buffer ...

  14. Mechanism of Cu+-transporting ATPases: Soluble Cu+ chaperones directly transfer Cu+ to transmembrane transport sites

    OpenAIRE

    González-Guerrero, Manuel; Argüello, José M

    2008-01-01

    As in other P-type ATPases, metal binding to transmembrane metal-binding sites (TM-MBS) in Cu+-ATPases is required for enzyme phosphorylation and subsequent transport. However, Cu+ does not access Cu+-ATPases in a free (hydrated) form but is bound to a chaperone protein. Cu+ transfer from Cu+ chaperones to regulatory cytoplasmic metal-binding domains (MBDs) present in these ATPases has been described, but there is no evidence of a proposed subsequent Cu+ movement from the MBDs to the TM-MBS. ...

  15. Identification of a Novel System for Boron Transport: Atr1 Is a Main Boron Exporter in Yeast? †

    Science.gov (United States)

    Kaya, Alaattin; Karakaya, Huseyin C.; Fomenko, Dmitri E.; Gladyshev, Vadim N.; Koc, Ahmet

    2009-01-01

    Boron is a micronutrient in plants and animals, but its specific roles in cellular processes are not known. To understand boron transport and functions, we screened a yeast genomic DNA library for genes that confer resistance to the element in Saccharomyces cerevisiae. Thirty boron-resistant transformants were isolated, and they all contained the ATR1 (YML116w) gene. Atr1 is a multidrug resistance transport protein belonging to the major facilitator superfamily. C-terminal green fluorescent protein-tagged Atr1 localized to the cell membrane and vacuole, and ATR1 gene expression was upregulated by boron and several stress conditions. We found that atr1? mutants were highly sensitive to boron treatment, whereas cells overexpressing ATR1 were boron resistant. In addition, atr1? cells accumulated boron, whereas ATR1-overexpressing cells had low intracellular levels of the element. Furthermore, atr1? cells showed stronger boron-dependent phenotypes than mutants deficient in genes previously reported to be implicated in boron metabolism. ATR1 is widely distributed in bacteria, archaea, and lower eukaryotes. Our data suggest that Atr1 functions as a boron efflux pump and is required for boron tolerance. PMID:19414602

  16. Identification of a novel system for boron transport: Atr1 is a main boron exporter in yeast.

    Science.gov (United States)

    Kaya, Alaattin; Karakaya, Huseyin C; Fomenko, Dmitri E; Gladyshev, Vadim N; Koc, Ahmet

    2009-07-01

    Boron is a micronutrient in plants and animals, but its specific roles in cellular processes are not known. To understand boron transport and functions, we screened a yeast genomic DNA library for genes that confer resistance to the element in Saccharomyces cerevisiae. Thirty boron-resistant transformants were isolated, and they all contained the ATR1 (YML116w) gene. Atr1 is a multidrug resistance transport protein belonging to the major facilitator superfamily. C-terminal green fluorescent protein-tagged Atr1 localized to the cell membrane and vacuole, and ATR1 gene expression was upregulated by boron and several stress conditions. We found that atr1Delta mutants were highly sensitive to boron treatment, whereas cells overexpressing ATR1 were boron resistant. In addition, atr1Delta cells accumulated boron, whereas ATR1-overexpressing cells had low intracellular levels of the element. Furthermore, atr1Delta cells showed stronger boron-dependent phenotypes than mutants deficient in genes previously reported to be implicated in boron metabolism. ATR1 is widely distributed in bacteria, archaea, and lower eukaryotes. Our data suggest that Atr1 functions as a boron efflux pump and is required for boron tolerance. PMID:19414602

  17. 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.)

  18. HYDROLOGICAL AND SEDIMENT TRANSPORT SIMULATION TO ASSESS THE IMPACT OF DAM CONSTRUCTION IN THE MEKONG RIVER MAIN CHANNEL

    OpenAIRE

    Satoshi Kameyama; Hiroto Shimazaki; Seiichi Nohara; Tatsuaki Sato; Yoshiaki Fujii; Keita Kudo

    2013-01-01

    The downstream impact of dams is a complex problem in watershed management. In the upper Mekong River watershed and its main channel, dam construction projects were started in the 1950s to meet increasing demands for energy and food production. Dams called the Mekong Cascade were completed on the Mekong River in China, the Manwan Dam in 1996 and the Dachaoshan Dam in 2003. We evaluated the impact of the Manwan Dam and its related watershed development on seasonal water discharge and suspended...

  19. Gabapentin increases extracellular glutamatergic level in the locus coeruleus via astroglial glutamate transporter-dependent mechanisms

    OpenAIRE

    Suto, Takashi; Severino, Amie L.; Eisenach, James. C.; Hayashida, Ken-ichiro

    2014-01-01

    Gabapentin has shown to be effective in animals and humans with acute postoperative and chronic pain. Yet the mechanisms by which gabapentin reduces pain have not been fully addressed. The current study performed in vivo microdialysis in the locus coeruleus (LC) in normal and spinal nerve ligated (SNL) rats to examine the effect of gabapentin on extracellular glutamate concentration and its mechanisms of action with focus on presynaptic GABA-B receptors, astroglial glutamate transporter-1 (GL...

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

    OpenAIRE

    Emmons, L. K.; Hess, P. G.; 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 ...

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

    OpenAIRE

    Ganeshkumar, P.; P. Gokulakrishnan

    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...

  2. 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)

  3. 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.

  4. Substrate specificity and transport mechanism of amino-acid transceptor Slimfast from Aedes aegypti.

    Science.gov (United States)

    Boudko, Dmitri Y; Tsujimoto, Hitoshi; Rodriguez, Stacy D; Meleshkevitch, Ella A; Price, David P; Drake, Lisa L; Hansen, Immo A

    2015-01-01

    Anautogenous mosquitoes depend on vertebrate blood as nutrient source for their eggs. A highly efficient set of membrane transporters mediates the massive movement of nutrient amino acids between mosquito tissues after a blood meal. Here we report the characterization of the amino-acid transporter Slimfast (Slif) from the yellow-fever mosquito Aedes aegypti using codon-optimized heterologous expression. Slif is a well-known component of the target-of-rapamycin signalling pathway and fat body nutrient sensor, but its substrate specificity and transport mechanism were unknown. We found that Slif transports essential cationic and neutral amino acids with preference for arginine. It has an unusual dual-affinity mechanism with only the high affinity being Na(+) dependent. Tissue-specific expression and blood meal-dependent regulation of Slif are consistent with conveyance of essential amino acids from gut to fat body. Slif represents a novel transport system and type of transceptor for sensing and transporting essential amino acids during mosquito reproduction. PMID:26449545

  5. Mechanisms of cellular uptake, intracellular transportation, and degradation of CIGB-300, a Tat-conjugated peptide, in tumor cell lines.

    Science.gov (United States)

    Benavent Acero, Fernando R; Perera Negrin, Yasser; Alonso, Daniel F; Perea, Silvio E; Gomez, Daniel E; Farina, Hernán G

    2014-06-01

    CIGB-300 is a cyclic synthetic peptide that induces apoptosis in malignant cells, elicits antitumor activity in cancer animal models, and shows tumor reduction signs when assayed in first-in-human phase I trial in patients with cervical tumors. CIGB-300 impairs phosphorylation by casein kinase 2 through targeting the substrate's phosphoacceptor domain. CIGB-300 was linked to the cell penetrating peptide Tat to facilitate the delivery into cells. Previously, we showed that CIGB-300 had a differential antiproliferative behavior in different tumor cell lines. In this work, we studied differential antiproliferative behavior in terms of cellular uptake, intracellular transportation, and degradation in tumor cell lines with dissimilar sensitivity to CIGB-300. The internalization of CIGB-300 was studied in different malignant cell lines. We found that the cell membrane heparan sulfate proteoglycans act as main receptors for extracellular CIGB-300 uptake. The most sensitive tumor cell lines showed higher intracellular incorporation of CIGB-300 in comparison to less sensitive cell lines. Furthermore, CIGB-300 uptake is time- and concentration-dependent in all studied cell lines. It was shown that CIGB-300 has the ability to penetrate cells mainly by direct membrane translocation. However, a minor proportion of the peptide uses an energy-dependent endocytic pathway mechanism to gain access into cells. CIGB-300 is internalized and transported into cells preferentially by caveolae-mediated endocytosis. Lysosomes are involved in CIGB-300 degradation; highly sensitive cell lines showed degradation at earlier times compared to low sensitive cells. Altogether, our data suggests a mechanism of internalization, vesicular transportation, and degradation for CIGB-300 in tumor cells. PMID:24773585

  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/?m 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. Mechanical environmental transport of actinides and ¹³?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

  8. 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

  9. 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...

  10. Transport mechanisms for the uptake of organic compounds by rice (Oryza sativa) roots

    Energy Technology Data Exchange (ETDEWEB)

    Su Yuhong [Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Chemistry Department, Xinjiang University, Urumqi 830046 (China); Zhu Yongguan [Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China)]. E-mail: ygzhu@rcees.ac.cn

    2007-07-15

    Uptake of six organic compounds, dinitrobenzene (DNB), dinitrotoluene (DNT), lindan (LIN), 1,2,3-triclorobenzene (TCB), phenanthrene (PHN) and pyrene (PYR) by freshly excised rice roots and dead rice roots (heated for 40 min at 105 {sup o}C) were investigated. Results indicated that the uptake by the two types of roots did not increase proportionally with those in external solution. There appears to be some special chemical function of root cells other than simple absorption by the cells. The contribution of this special function can be roughly estimated by deducting the partition uptake into cells from the total uptake. Both time-dependent uptake data and concentration-dependent uptake curves demonstrate that, DNT and DNB transport is achieved presumably mainly via the symplastic pathway, while PHN and PYR transport mainly via the apoplastic pathway. For LIN and TCB, apoplastic transport pathway plays major roles in the first 2 h of uptake, then symplastic transport pathway dominates uptake. - Different organic compounds may be transported via different pathways in plant roots depending on log K {sub ow}.

  11. Transport mechanisms for the uptake of organic compounds by rice (Oryza sativa) roots

    International Nuclear Information System (INIS)

    Uptake of six organic compounds, dinitrobenzene (DNB), dinitrotoluene (DNT), lindan (LIN), 1,2,3-triclorobenzene (TCB), phenanthrene (PHN) and pyrene (PYR) by freshly excised rice roots and dead rice roots (heated for 40 min at 105 oC) were investigated. Results indicated that the uptake by the two types of roots did not increase proportionally with those in external solution. There appears to be some special chemical function of root cells other than simple absorption by the cells. The contribution of this special function can be roughly estimated by deducting the partition uptake into cells from the total uptake. Both time-dependent uptake data and concentration-dependent uptake curves demonstrate that, DNT and DNB transport is achieved presumably mainly via the symplastic pathway, while PHN and PYR transport mainly via the apoplastic pathway. For LIN and TCB, apoplastic transport pathway plays major roles in the first 2 h of uptake, then symplastic transport pathway dominates uptake. - Different organic compounds may be transported via different pathways in plant roots depending on log K ow

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

    Energy Technology Data Exchange (ETDEWEB)

    Farag, A.A.M. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Heliopolis, Cairo 11757 (Egypt)], E-mail: alaafaragg@yahoo.com

    2009-01-01

    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.

  13. 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.

  14. About charge-transport mechanisms in mesoporous silicon under adsorption of plant viruses

    Energy Technology Data Exchange (ETDEWEB)

    Vashpanov, Yuriy; Kwack, Kae-Dal; Woo, Sun-Bo [Research Institute of Electrical and Computer Engineering, HIT Hanyang University, Seongdong-ku, Seoul (Korea); Son, Jung-Young [School of Computer and Communication Engineering, Daegu University, Kyungsan, Kyungbuk (Korea); Choi, Kyu-Hwan [Physics Department, Korea University, Seoul (Korea)

    2009-07-15

    Changes in the electric parameters and the charge-transport mechanism in a mesoporous silicon under adsorption of TORSV (tomato ringspot virus) and GFLV (grapevine fan leaf virus) NEPO-viruses are analyzed. The mechanism influencing the electric characteristics of the mesoporous silicon under adsorption of the plant viruses is related with the changes in parameters of a potential-barrier system due to redistribution of voltages at the silicon structure. The mechanism of charge transport in the mesoporous silicon is more likely connected to the changes in parameters of isotopic heterojunction barriers under small bias voltages, and it can be interpreted as Poole-Frenkel and tunnel conductivity for large bias. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Mimicking cellular transport mechanism in stem cells through endosomal escape of new peptide-coated quantum dots

    Science.gov (United States)

    Narayanan, Karthikeyan; Yen, Swee Kuan; Dou, Qingqing; Padmanabhan, Parasuraman; Sudhaharan, Thankiah; Ahmed, Sohail; Ying, Jackie Y.; Selvan, Subramanian Tamil

    2013-07-01

    Protein transport is an important phenomenon in biological systems. Proteins are transported via several mechanisms to reach their destined compartment of cell for its complete function. One such mechanism is the microtubule mediated protein transport. Up to now, there are no reports on synthetic systems mimicking the biological protein transport mechanism. Here we report a highly efficient method of mimicking the microtubule mediated protein transport using newly designed biotinylated peptides encompassing a microtubule-associated sequence (MTAS) and a nuclear localization signaling (NLS) sequence, and their final conjugation with streptavidin-coated CdSe/ZnS quantum dots (QDs). Our results demonstrate that these novel bio-conjugated QDs enhance the endosomal escape and promote targeted delivery into the nucleus of human mesenchymal stem cells via microtubules. Mimicking the cellular transport mechanism in stem cells is highly desirable for diagnostics, targeting and therapeutic applications, opening up new avenues in the area of drug delivery.

  16. 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

  17. 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

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    Radenovi? ?edomir 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.

  20. 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.

  1. New mechanism for amino acid influx into human epidermal Langerhans cells: L-dopa/proton counter-transport system.

    OpenAIRE

    Falck, Bengt; Bendsöe, Niels; Ronquist, Gunnar

    2003-01-01

    We have characterized a stereospecific transport mechanism for L-dopa into human epidermal Langerhans cells (LCs). It is different from any other amino acid transport system. It is highly concentrative, largely pH-independent, and independent of exogenous Na+, glucose and oxygen, and fuelled by a renewable intracellular energy source inhibited by iodoacetate but not by arsenate. We propose that the mechanism is a unidirectional L-dopa/proton counter-transport system. We have recently demonstr...

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

    DEFF Research Database (Denmark)

    Klitkou, Antje; Bolwig, Simon

    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 returns, technological interrelatedness, collective action, institutional learning effects and the differentiation of power. We show that very different path dependencies have been reinforced by the lock-in mechanisms. Hence, the characteristics of existing regimes set the preconditions for the development of new transition pathways. The incumbent socio-technical regime is not just fossil-based, but may also include mature niches specialised in the exploitation of renewable sources. This implies a need to distinguish between lock-in mechanisms favouring the old fossil-based regime, well-established (mature) renewable energy niches, or new pathways.

  3. Investigation of Sediment Transport Mechanisms in the Durres Gulf – Albania Using Radiotracers [Case Study: Radiotracer Applications for Investigation of Bedload Transport of Sediments

    International Nuclear Information System (INIS)

    The radiotracer study had the following objectives: • to clarify the mechanism and to obtain quantitative results regarding the sediment transport in the gulf of Durres; • to find the sediment transport direction and quantity in the vicinity of the access channel of Durres port; • to determine the sediment quantity deposed every year in the channel

  4. 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

  5. Modeling of Colloid Transport Mechanisms Facilitating Migration of Radionuclides in Fractured Media

    International Nuclear Information System (INIS)

    Performance assessments of high-level radioactive waste disposal have emphasized the role of colloids in the migration of radionuclides in the geosphere. The transport of colloids often brings them in contact with fracture surfaces or porous rock matrix. Colloids that attach to these surfaces are treated as being immobile and are called filtered colloids. The filtered colloids could be released into the fracture again; that is, the attachment of colloids may be reversible. Also, the colloids in the fracture could diffuse into the porous matrix rock. A methodology is proposed to evaluate a predictive model to assess transport within the fractured rock as well as various phenomenological coefficients employed in the different mechanisms, such as filtration, remobilization, and matrix diffusion of colloids. The governing equations of colloids considering mechanisms of the colloidal transport in the fractured media, including filtration, remobilization, and matrix diffusion, have been modeled and solved analytically in previous studies. In the present study, transport equations of colloids and radionuclides that consider the combination of the aforementioned transport mechanisms have also been solved numerically and investigated. The total concentration of mobile radionuclides in the fracture becomes lower because the concentration of mobile colloids in the fracture decreases when the filtration coefficient for colloids increases. Additionally, the concentration of mobile radionuclides was increased at any given time step due to the higher sorption partition coefficient of radionuclides associated with colloids. The results also show that the concentration of radionuclides in the fracture zone decreases when the remobilization coefficient of colloids or the percentages of the matrix diffusion flux of colloids increase

  6. 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

  7. 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...

  8. 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.

  9. Advances in the numerical treatment of grain-boundary migration: Coupling with mass transport and mechanics

    CERN Document Server

    Mourad, H M; Mourad, Hashem M.; Garikipati, Krishna

    2004-01-01

    This work is based upon a coupled, atomically-based continuum formulation that was previously applied to problems involving strong coupling between mechanics and mass transport; e.g. diffusional creep and electromigration. Here we discuss an enhancement of this formulation to account for migrating grain boundaries. The treatment is based on the level set method and can easily be generalized to model other problems with migrating interfaces; e.g. void evolution and free-surface morphology evolution. The level-set formulation developed is remarkably simple and obviates the need for spatial stabilization. It also makes use of velocity extension, field re-initialization and least-squares smoothing techniques. The latter allow the local curvature of a grain boundary to be computed directly from the level-set field without resorting to higher-order interpolation. A notable feature is that the coupling between mass transport, mechanics and grain-boundary migration is fully accounted for. The complexities associated ...

  10. 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.

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

    International Nuclear Information System (INIS)

    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

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

    Czech Academy of Sciences Publication Activity Database

    P?evorovská, Sv?tlana; 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 ?R GA106/98/1373 Grant ostatní: PP ÚT AV ?R(XC) 2/50 U Keywords : human cardiovascular system * myocardium * membrane transport Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  13. Mechanically reinforced MgB2 wires and tapes with high transport currents

    OpenAIRE

    Nast, R.; Schlachter, S. I.; Zimmer, S.; H.; Reiner; Goldacker, W.

    2001-01-01

    Monofilamentary MgB2-wires with a 2- or 3-component sheath containing mechanical reinforcing stainless steel (SS) were prepared and characterized. In direct contact to the superconductor Nb, Ta or Fe was used. For a selection of samples with a Fe and Fe/SS sheath, we investigated the transport critical current behaviour in magnetic fields changing systematically the geometrical shape from a round wire to a flat tape. A strong increase of the current densities in flat tapes w...

  14. Ovariectomy Enhances Mechanical Load-Induced Solute Transport around Osteocytes in Rat Cancellous Bone

    OpenAIRE

    Ciani, Cesare; Sharma, Divya; Stephen B. Doty; Fritton, Susannah P.

    2013-01-01

    To test if osteoporosis alters mechanical load-induced interstitial fluid flow in bone, this study examined the combined effect of estrogen deficiency and external loading on solute transport around osteocytes. An in vivo tracer, FITC-labeled bovine serum albumin, was injected into anaesthetized ovariectomized and control female Sprague Dawley rats before the right tibia was subjected to a controlled, physiological, non-invasive sinusoidal load to mimic walking. Tracer movement through the la...

  15. 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...

  16. Charge Carrier Transport Mechanism Based on Stable Low Voltage Organic Bistable Memory Device.

    Science.gov (United States)

    Ramana, V V; Moodley, M K; Kumar, A B V Kiran; Kannan, V

    2015-05-01

    A solution processed two terminal organic bistable memory device was fabricated utilizing films of polymethyl methacrylate PMMA/ZnO/PMMA on top of ITO coated glass. Electrical characterization of the device structure showed that the two terminal device exhibited favorable switching characteristics with an ON/OFF ratio greater than 1 x 10(4) when the voltage was swept between - 2 V and +3 V. The device maintained its state after removal of the bias voltage. The device did not show degradation after a 1-h retention test at 120 degrees C. The memory functionality was consistent even after fifty cycles of operation. The charge transport switching mechanism is discussed on the basis of carrier transport mechanism and our analysis of the data shows that the charge carrier trans- port mechanism of the device during the writing process can be explained by thermionic emission (TE) and space-charge-limited-current (SCLC) mechanism models while erasing process could be explained by the FN tunneling mechanism. This demonstration provides a class of memory devices with the potential for low-cost, low-power consumption applications, such as a digital memory cell. PMID:26505027

  17. Variability of the transport of anthropogenic CO2 at the Greenland–Portugal OVIDE section: controlling mechanisms

    Directory of Open Access Journals (Sweden)

    P. Zunino

    2013-10-01

    Full Text Available The interannual to decadal variability of the transport of anthropogenic carbon dioxide (Cant across the Subpolar North Atlantic (SPNA is investigated, using data of the OVIDE high resolution transoceanic section, from Greenland to Portugal, occupied six times from 1997 to 2010. The transport of Cant across this section, TCant hereafter, is northward, with a mean value of 254 ± 29 kmol s–1 over the 1997–2010 period. The TCant presents a high interannual variability, masking any trend different from 0 for this period. In order to understand the mechanisms controlling the variability of the TCant across the SPNA, we propose a new method that quantifies the transport of Cant caused by the diapycnal and isopycnal circulation. The diapycnal component yields a large northward transport of Cant (400 ± 29 kmol s–1 which is partially compensated by a southward transport of Cant caused by the isopycnal component (–171 ± 11 kmol s–1, mainly localized in the Irminger Sea. Most importantly, the diapycnal component is found to be the main driver of the variability of the TCant across the SPNA. Both the Meridional Overturning Circulation (MOC and the Cant increase in the water column have an important effect on the variability of the diapycnal component and of the TCant itself. Based on this analysis, we propose a simplified estimator for the variability of the TCant based on the intensity of the MOC and on the difference of Cant between the upper and lower limb of the MOC (?Cant. This estimator shows a good consistency with the diapycnal component of the TCant, and help to disentangle the effect of the variability of both the circulation and the Cant increase on the TCant variability. We find that ?Cant keeps increasing over the past decade, and it is very likely that the continuous Cant increase in the water masses will cause an increase in the TCant across the SPNA at long time scale. Nevertheless, at the time scale analyzed here (1997–2010, the MOC is controlling the TCant variability, blurring the expected TCant increase. Extrapolating the observed ?Cant increase rate and considering the predicted slow-down of 25% of the MOC, the TCant across the SPNA is expected to increase by 430 kmol s–1 during the 21st century. Consequently, an increase in the storage rate of Cant in the SPNA could be envisaged.

  18. 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.

  19. 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

  20. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Iliev, Bozhidar Z. [Department of Mathematical Modeling, Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia (Bulgaria)]. E-mail: bozho@inrne.bas.bg

    2001-06-15

    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)

  2. Vibrações mecânicas: um agente estressor no transporte de pintos / Mechanical vibrations: a stressor in the transport of chicken

    Scientific Electronic Library Online (English)

    Ana C., Donofre; Iran J. O. da, Silva; Aérica C., Nazareno.

    2014-04-01

    Full Text Available As vibrações mecânicas, presentes no transporte de cargas vivas, podem comprometer a estabilidade fisiológica e o futuro desempenho dos animais de produção. O objetivo desta pesquisa foi avaliar, por meio de simulações, o efeito de dois níveis de aceleração (9,64 e 15,19 m s-2) sobre o estresse e o [...] desempenho de pintos de corte de um dia. As vibrações foram simuladas utilizando-se um agitador mecânico e as intensidades de vibração estudadas por valores de aceleração geral. O período de simulação durou duas horas para cada tratamento e as aves tiveram seus parâmetros (diferença de peso; frequência respiratória e desempenho na primeira semana) comparados a grupos-controle (sem vibração). Realizou-se um delineamento inteiramente casualizado em que os resultados obtidos indicaram que esses níveis não influenciaram significativamente (p Abstract in english Mechanical vibrations present in transporting live loads can impair physiologic stability and the future performance of livestock. The aim of this study was to evaluate, using simulations, the effect of two levels of vibration (9.64 and 15.19 m s-2) in stress responses and performance of day-old chi [...] cken. The vibrations were simulated by means of a shaking machine and studied by general acceleration values. The simulation period lasted two hours for each treatment and the birds had their parameters (difference in weight, respiratory rate, and performance in the first week) compared to control groups (without vibration). The experiment was conducted in a randomized design and the results showed that these levels did not differ significantly (p

  3. In vivo imaging of oskar mRNA transport reveals the mechanism of posterior localization.

    Science.gov (United States)

    Zimyanin, Vitaly L; Belaya, Katsiaryna; Pecreaux, Jacques; Gilchrist, Michael J; Clark, Alejandra; Davis, Ilan; St Johnston, Daniel

    2008-09-01

    oskar mRNA localization to the posterior of the Drosophila oocyte defines where the abdomen and germ cells form in the embryo. Although this localization requires microtubules and the plus end-directed motor, kinesin, its mechanism is controversial and has been proposed to involve active transport to the posterior, diffusion and trapping, or exclusion from the anterior and lateral cortex. By following oskar mRNA particles in living oocytes, we show that the mRNA is actively transported along microtubules in all directions, with a slight bias toward the posterior. This bias is sufficient to localize the mRNA and is reversed in mago, barentsz, and Tropomyosin II mutants, which mislocalize the mRNA anteriorly. Since almost all transport is mediated by kinesin, oskar mRNA localizes by a biased random walk along a weakly polarized cytoskeleton. We also show that each component of the oskar mRNA complex plays a distinct role in particle formation and transport. PMID:18775316

  4. 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.)

  5. 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.

  6. Designing and testing regenerative pulp treatment strategies: modeling the transdentinal transport mechanisms

    Science.gov (United States)

    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 investigation on the development of a methodology that can calculate the transport rate of selected molecules inside a typical dentinal tubule. The transport rate of biological molecules has been investigated using a validated CFD code. In that framework we propose a simple algorithm that, given the type of molecules of the therapeutic agent and the maximum acceptable time for the drug concentration to attain a required value at the pulpal side of the tubules, can estimate the initial concentration to be imposed. PMID:26441676

  7. Growth dynamics and gas transport mechanism of nanobubbles in graphene liquid cells

    Science.gov (United States)

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

    2015-02-01

    Formation, evolution and vanishing of bubbles are common phenomena in nature, which can be easily observed in boiling or falling water, carbonated drinks, gas-forming electrochemical reactions and so on. 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 the liquid phase. Here, we demonstrate for the first time that the nanobubbles in water encapsulated by graphene membrane can be visualized by in-situ ultra-high vacuum transmission electron microscopy. Our microscopic results indicate two distinct growth mechanisms of merging nanobubbles and the existence of a critical radius of nanobubbles that determines the unusually long stability of nanobubbles. 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 condensation, transmission and evaporation.

  8. 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

  9. 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...

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

    Science.gov (United States)

    Kawaguchi, Riki; Zhong, Ming; Kassai, Miki; Ter-Stepanian, Mariam; Sun, Hui

    2015-01-01

    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. PMID:26343735

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

    Science.gov (United States)

    Kawaguchi, Riki; Zhong, Ming; Kassai, Miki; Ter-Stepanian, Mariam; Sun, Hui

    2015-01-01

    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. PMID:26343735

  12. Fibre bundle formulation of nonrelativistic quantum mechanics; 1, Introduction The evolution transport

    CERN Document Server

    Iliev, Bozhidar Z

    1998-01-01

    We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one but it is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it a pure state of some quantum system is described by a state section (along paths) of a (Hilbert) fibre bundle. It's evolution is determined through the bundle (analogue of the) Schrödinger equation. Now the dynamical variables and the density operator are described via bundle morphisms (along paths). The mentioned quantities are connected by a number of relations derived in this work. 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 sections in the Hilbert f...

  13. 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

  14. Monte Carlo study in the mechanisms of transport of fast neutrons in various media

    International Nuclear Information System (INIS)

    The life histories of fast neutrons created by the straight Monte Carlo method in various attenuation media were examined. The media studied range from the one with simple, featureless properties (Na) to iron with very complicated cross section structure. The life histories of exceptional neutrons, i.e. those staying very close to the source, or those going very far from the source, were compared with those of the general population. When the exceptional neutrons exploited a particular collision property in a narrow energy band in order to reach a given detector, the method of analyzing Monte Carlo histories was able to provide a clear physical picture and single out the influence of that property on the macroscopic behavior of the neutrons. Two such phenomena were demonstrated by using this technique. In one, transport in a cross section minimum dominates the deep penetration of the neutrons. In such a circumstance most of the spatial transport is accomplished by the traveling at energies in and near the minimum, while little transport occurs at any other energies. The second example involves the effect of inelastic scattering on the low-energy leakage spectra for small bare assemblies. It is shown that, for a small bare iron sphere and for a fission source, the exit current spectrum below 100 keV is extremely sensitive to the details of the inelastic scattering near threshold. It often happened that in some exceptional situations the number of histories available for the analysis was too few to give statistically significant results. The most important conclusion to be drawn here is that the analysis of Monte Carlo histories can provide information on the details of transport mechanisms that is not available through forward or even adjoint deterministic transport calculations. 47 figures, 21 tables

  15. 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 ? = 915 nm and under UV irradiation with an excimer laser (? = 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)

  16. 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

  17. Recent fracture mechanics results from NASA research related to the aging commercial transport fleet

    Science.gov (United States)

    Harris, Charles E.

    1991-01-01

    NASA is conducting the Airframe Structural Integrity Program in support of the aging commercial transport fleet. This interdisciplinary program is being worked in cooperation with the U.S. airframe manufacturers, airline operators, and the FAA. Advanced analysis methods are under development to predict the fatigue crack growth in complex built-up shell structures. Innovative nondestructive examination technologies are also under development to provide large area inspection capability to detect corrosion, disbonds, and fatigue cracks. Recent fracture mechanics results applicable to predicting the growth of cracks initiating at the rivets of fuselage splice joints are reviewed.

  18. Fracture mechanics research at NASA related to the aging commercial transport fleet

    Science.gov (United States)

    Newman, James C., Jr.; Harris, Charles E.

    1992-01-01

    NASA is conducting the Airframe Structural Integrity Program in support of the aging commercial transport fleet. This interdisciplinary program is being worked in cooperation with the U.S. airframe manufacturers, airline operators, and the FAA. Advanced analysis methods are under development and an extensive testing program is under way to study fatigue crack growth and fracture in complex built-up shell structures. Innovative nondestructive examination technologies are also being developed to provide large area inspection capability to detect corrosion, disbonds, and cracks. Recent fracture mechanics results applicable to predicting the growth of cracks under monotonic and cyclic loading at rivets in fuselage lap-splice joints are reviewed.

  19. 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.

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

    OpenAIRE

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

  1. Control of oxygen transport in the microcrustacean Daphnia: regulation of haemoglobin expression as central mechanism of adaptation to different oxygen and temperature conditions.

    Science.gov (United States)

    Paul, R J; Zeis, B; Lamkemeyer, T; Seidl, M; Pirow, R

    2004-11-01

    The pathway for oxygen, the control of oxygen transport and the role of haemoglobin expression for the physiological adaptation to different oxygen and temperature conditions were studied in the ecological model organism Daphnia magna. Ventilation of the inner walls of the carapace as the main gas exchange area as well as of the embryos in the brood pouch are controlled, oxygen-dependent processes. The P(O2)-dependent increase of heart rate as well as perfusion rate during short-term, progressive hypoxia improves the circulatory oxygen transport within the body. The regulation of haemoglobin (Hb) expression is the central mechanism for a medium-term adaptation to hypoxia. Genetic control elements and oxygen conditions near the two Hb synthesis sites (fat cells, epipodite epithelial cells) determine, which types of Hb subunits and, accordingly, hetero-multimeric Hb macromolecules are produced. One synthesis site may respond mainly to internal, the other one to external oxygen conditions. Depending on environmental condition, either higher quantities of macromolecules of unchanged functionality (P50) or increasing amounts of macromolecules with higher oxygen affinity are synthesized. The Hb subunit DmHbA is probably of considerable importance for this functional change. The physiological benefits of haemoglobin in Daphnia are discussed. Physiological adaptation of Daphnia to different temperatures is also related to the control of oxygen transport processes with the regulation of haemoglobin expression again as a central mechanism. PMID:15491405

  2. Elastic tunneling charge transport mechanisms in silicon quantum dots /SiO2 thin films and superlattices

    International Nuclear Information System (INIS)

    The role of different charge transport mechanisms in Si/SiO2 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 SiO2 is the most relevant process. Besides, current trends in Si/SiO2 superlattice structure have been properly reproduced

  3. Molecular mechanism of pH-dependent substrate transport by an arginine-agmatine antiporter

    Science.gov (United States)

    Wang, Sheng; Yan, Renhong; Zhang, Xi; Chu, Qi; Shi, Yigong

    2014-01-01

    Enteropathogenic bacteria, exemplified by Escherichia coli, rely on acid-resistance systems (ARs) to survive the acidic environment of the stomach. AR3 consumes intracellular protons through decarboxylation of arginine (Arg) in the cytoplasm and exchange of the reaction product agmatine (Agm) with extracellular Arg. The latter process is mediated by the Arg:Agm antiporter AdiC, which is activated in response to acidic pH and remains fully active at pH 6.0 and below. Despite our knowledge of structural information, the molecular mechanism by which AdiC senses acidic pH remains completely unknown. Relying on alanine-scanning mutagenesis and an in vitro proteoliposome-based transport assay, we have identified Tyr74 as a critical pH sensor in AdiC. The AdiC variant Y74A exhibited robust transport activity at all pH values examined while maintaining stringent substrate specificity for Arg:Agm. Replacement of Tyr74 by Phe, but not by any other amino acid, led to the maintenance of pH-dependent substrate transport. These observations, in conjunction with structural information, identify a working model for pH-induced activation of AdiC in which a closed conformation is disrupted by cation–? interactions between proton and the aromatic side chain of Tyr74. PMID:25136114

  4. 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.

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

    International Nuclear Information System (INIS)

    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

  6. Constraints on Transport and Emplacement Mechanisms of Labile Fractions in Lunar Cold Traps

    Science.gov (United States)

    Rickman, D.; Gertsch, L.

    2014-01-01

    Sustaining the scientific exploration of the Solar System will require a significant proportion of the necessary fuels and propellants, as well as other bulk commodities, to be produced from local raw materials [1]. The viability of mineral production depends on the ability to locate and characterize mineable deposits of the necessary feedstocks. This requires, among other things, a workable understanding of the mechanisms by which such deposits form, which is the subject of Economic Geology. Multiple deposition scenarios are possible for labile materials on the Moon. This paper suggests labile fractions moved diffusely through space; deposits may grow richer with depth until low porosity rock; lateral transport is likely to have occurred with the regolith, at least for short distances; crystalline ice may not exist; the constituent phases could be extremely complex. At present we can constrain the sources only mildly; once on the Moon, the transport mechanisms inherently mix and therefore obscure the origins. However, the importance of expanding our understanding of ore-forming processes on the Moon behooves us to make the attempt. Thus begins a time of new inquiry for Economic Geology.

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

    Science.gov (United States)

    Altuntas, Halit; Ozgit-Akgun, Cagla; Donmez, Inci; Biyikli, Necmi

    2015-04-01

    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.

  8. Carrier transport mechanism of Mo contact to amorphous hafnium indium zinc oxides

    International Nuclear Information System (INIS)

    We investigated the carrier transport mechanism of Mo contacts to amorphous hafnium indium zinc oxides (a-HIZO). As-deposited Mo exhibited nearly ohmic behavior, while the thermal annealing improved the ohmic contact significantly, i.e. the specific contact resistance was 1.9 x 10-1, 4.3 x 10-3, and 1.5 x 10-3 ? cm2 for the as-deposited, 200 and 400 C-annealed condition, respectively. The ohmic mechanism of as-deposited Mo contact might be attributed to the barrier inhomogeneity and/or to the trap-assisted tunneling. For the annealed contact, the carrier transport could be explained by thermionic field emission model, yielding a tunneling parameter of 57 meV and a Schottky barrier height of 0.82 eV, i.e. the ohmic behavior is due to the tunneling through thin barrier. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Carrier transport mechanism of Mo contact to amorphous hafnium indium zinc oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seongjun; Gil, Youngun; Kim, Hyunsoo [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center, Chonbuk National University, 561-756, Jeonju (Korea, Republic of); Kim, Kyoung-Kook [Department of Nano-Optical Engineering, Korea Polytechnic University, 429-793, Siheung (Korea, Republic of); Ahn, Kwang-Soon [School of Chemical Engineering, Yeungnam University, Gyeongsan, 712-749, Gyeongbuk (Korea, Republic of)

    2014-08-15

    We investigated the carrier transport mechanism of Mo contacts to amorphous hafnium indium zinc oxides (a-HIZO). As-deposited Mo exhibited nearly ohmic behavior, while the thermal annealing improved the ohmic contact significantly, i.e. the specific contact resistance was 1.9 x 10{sup -1}, 4.3 x 10{sup -3}, and 1.5 x 10{sup -3} ? cm{sup 2} for the as-deposited, 200 and 400 C-annealed condition, respectively. The ohmic mechanism of as-deposited Mo contact might be attributed to the barrier inhomogeneity and/or to the trap-assisted tunneling. For the annealed contact, the carrier transport could be explained by thermionic field emission model, yielding a tunneling parameter of 57 meV and a Schottky barrier height of 0.82 eV, i.e. the ohmic behavior is due to the tunneling through thin barrier. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Mechanisms of zinc uptake in gills of freshwater rainbow trout: interplay with calcium transport.

    Science.gov (United States)

    Hogstrand, C; Verbost, P M; Bonga, S E; Wood, C M

    1996-05-01

    The uptake mechanism of Zn2+ through the gill epithelium of freshwater rainbow trout was investigated both in intact animals and in isolated basolateral membranes. Involvement of the apical Ca2+ uptake sites in Zn2+ uptake was examined in vivo by pharmacological manipulation of the apical Ca2+ permeability. The apical entries of Ca2+ and Zn2+, but not Na2+ and Cl-, were inhibited by addition of La to the water. Addition of 1.0 microM La reduced the influxes of Ca2+ and Zn2+ to 22 +/- 3 and 53 +/- 7% (mean +/- SE) of the control value, respectively. Injection of CaCl2 also reduced the branchial influxes of Ca2+ and Zn2+. This treatment decreased the influx of Ca2- to 45 +/- 4% of the control level and the Zn2+ influx to 68 +/- 5%. These results strongly imply that Zn2+ passes across the apical membrane of the chloride cells of the gills via the same pathway as Ca2+. The presence of an active basolateral transporter for Zn2+ was investigated in vitro on isolated basolateral membranes. There was no ATP-dependent or Na2+(-)gradient driven transport of Zn2+ at physiological Zn2+ activities. The same system was used to study potential effects of Zn2+ on the basolateral Ca2+(-)adenosinetri-phosphatase. Zn2+ was found to be a potent blocker of this transporter, causing a mixed inhibitory effect on the ATP driven Ca2+ transport at a free Zn2+ activity of 100 pM. PMID:8928918

  15. 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)

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

    DEFF Research Database (Denmark)

    Dölger, Julia; Rademaker, Hanna

    2014-01-01

    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.

  17. Thermopower and transport mechanism of the La2-xSrxCu0.94Ti0.06O4 system

    Science.gov (United States)

    Wang, Caixia; Chen, Xiaobing; Zhu, Aiping

    2012-06-01

    The thermal properties and their relationship to the charge transport properties of the La2-xSrxCu0.94Ti0.06O4 solid solution series have been investigated by means of electric resistivity and thermopower measurements. The different changes of the broad peak in S-T curves for Sr-doped samples were observed, which may result from the itinerant hole carriers. The transport mechanism of La2-xSrxCu0.94Ti0.06O4 is mainly dominated by the small-polaron hopping due to the discrepancy in the activation energy derived from the resistivity and the thermoelectric power. The small polarons are not originated from the magnetic coupling between magnetic ions and hole spins, but from the coupling between the phonon with a breathing mode and the hole carriers.

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

    Energy Technology Data Exchange (ETDEWEB)

    Uren, Michael J.; Cäsar, 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.

  19. 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.

  20. 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.

  1. Impact of strong magnetic fields on collision mechanism for transport of charged particles

    CERN Document Server

    Bostan, Mihai

    2012-01-01

    One of the main applications in plasma physics concerns the energy production through thermo-nuclear fusion. The controlled fusion is achieved by magnetic confinement i.e., the plasma is confined into a toroidal domain (tokamak) under the action of huge magnetic fields. Several models exist for describing the evolution of strongly magnetized plasmas, most of them by neglecting the collisions between particles. The subject matter of this paper is to investigate the effect of large magnetic fields with respect to a collision mechanism. We consider here linear collision Boltzmann operators and derive, by averaging with respect to the fast cyclotronic motion due to strong magnetic forces, their effective collision kernels.

  2. Sub-continental transport mechanisms and pathways during two ozone episodes in northern Spain

    Directory of Open Access Journals (Sweden)

    G. Gangoiti

    2006-01-01

    Full Text Available Two ozone episodes (occurring in June 2001 and June 2003 in the air quality monitoring network of the Basque Country (BC are analyzed. The population information threshold was exceeded in many stations (urban, urban-background and rural. During this type of episodes, forced by a blocking anticyclone over the British Isles, ozone background concentrations over the area increase after the import of pollution from both, the continental Europe and the western Mediterranean areas (Gangoiti et al., 2002. For the present analysis, emphasis is made in the search for transport mechanisms, pathways and area sources contributing to the build-up of the episodes. Contributions from a selection of 17 urban and industrial conglomerates in the western European Atlantic (WEA and the western Mediterranean (WM are shown after the results of a coupled RAMS-HYPACT modelling system. Meteorological simulations are tested against both the high-resolution wind data recorded at the BC coastal area by a boundary layer wind-profiler radar (Alonso et al., 1998 and the wind soundings reported by the National Centres of Meteorology at a selection of European and north-African sites. Results show that during the accumulation phase of the episodes, background ozone concentrations increase in the whole territory as a consequence of transport from the Atlantic coast of France and the British Channel. For the peak phase, intrusions from new sources, located at the Western Mediterranean, Southern France, Ebro Valley, and, occasionally, the area of Madrid are added, resulting in a further increase in the ozone concentrations. Direct day and night transport within the north-easterly winds over the sea from the WEA source region, and night-time transport within the residual layer over continental areas (southern France, the Ebro Valley, and central Iberia modulate the import sequence of pollutants and the local increase of ozone concentrations. The alternative direct use of low resolution meteorological data for the estimation of back-trajectories shows a more simple transport scheme with no contributions neither from the Western Mediterranean nor from the Madrid area.

  3. 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.

  4. Transportation

    International Nuclear Information System (INIS)

    Here is the decree of the thirtieth of July 1998 relative to road transportation, to trade and brokerage of wastes. It requires to firms which carry out a road transportation as well as to traders and to brokers of wastes to declare their operations to the prefect. The declaration has to be renewed every five years. (O.M.)

  5. Ion transport mechanisms linked to bicarbonate secretion in the esophageal submucosal glands.

    Science.gov (United States)

    Abdulnour-Nakhoul, Solange; Nakhoul, Hani N; Kalliny, Medhat I; Gyftopoulos, Alex; Rabon, Edd; Doetjes, Rienk; Brown, Karen; Nakhoul, Nazih L

    2011-07-01

    The esophageal submucosal glands (SMG) secrete HCO(3)(-) and mucus into the esophageal lumen, where they contribute to acid clearance and epithelial protection. This study characterized the ion transport mechanisms linked to HCO(3)(-) secretion in SMG. We localized ion transporters using immunofluorescence, and we examined their expression by RT-PCR and in situ hybridization. We measured HCO(3)(-) secretion by using pH stat and the isolated perfused esophagus. Using double labeling with Na(+)-K(+)-ATPase as a marker, we localized Na(+)-coupled bicarbonate transporter (NBCe1) and Cl(-)-HCO(3)(-) exchanger (SLC4A2/AE2) to the basolateral membrane of duct cells. Expression of cystic fibrosis transmembrane regulator channel (CFTR) was confirmed by immunofluorescence, RT-PCR, and in situ hybridization. We identified anion exchanger SLC26A6 at the ducts' luminal membrane and Na(+)-K(+)-2Cl(-) (NKCC1) at the basolateral membrane of mucous and duct cells. pH stat experiments showed that elevations in cAMP induced by forskolin or IBMX increased HCO(3)(-) secretion. Genistein, an activator of CFTR, which does not increase intracellular cAMP, also stimulated HCO(3)(-) secretion, whereas glibenclamide, a Cl(-) channel blocker, and bumetanide, a Na(+)-K(+)-2Cl(-) blocker, decreased it. CFTR(inh)-172, a specific CFTR channel blocker, inhibited basal HCO(3)(-) secretion as well as stimulation of HCO(3)(-) secretion by IBMX. This is the first report on the presence of CFTR channels in the esophagus. The role of CFTR in manifestations of esophageal disease in cystic fibrosis patients remains to be determined. PMID:21474426

  6. Electron transport mechanism of thermally oxidized ZnO gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hardan, N.H., E-mail: naif.zd06@student.usm.m [School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Pulau Pinang (Malaysia); Abdullah, M.J.; Abdul Aziz, A. [School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Pulau Pinang (Malaysia)

    2010-11-01

    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 H{sub 2} 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 V

  7. Understanding Kondo Peak Splitting and Novel Transport Mechanism in a Single-Electron Transistor

    CERN Document Server

    Hong, J; Hong, Jongbae; Woo, Wonmyung

    2007-01-01

    The peculiar behavior of Kondo peak splitting under a magnetic field and bias can be explained by calculating the nonequilibrium retarded Green's function via the nonperturbative dynamical theory (NDT). In the NDT, the application of a lead-dot-lead system reveals that new resonant tunneling levels are activated near the Fermi level and the conventional Kondo peak at the Fermi level diminishes when a bias is applied. Magnetic field causes asymmetry in the spectral density and transforms the new resonant peak into a major peak whose behavior explains all the features of the nonequilibrium Kondo phenomenon. Transport through the new resonant tunneling level is a novel mechanism of current occurring in a single-electron transistor.

  8. 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.

  9. Electrical characteristics and carrier transport mechanism for Ti/ p-GaN Schottky diodes

    Science.gov (United States)

    Jang, Seon-Ho; Jang, Ja-Soon

    2013-03-01

    The temperature dependence of the electrical characteristics of non-alloyed Ti/ p-GaN Schottky diodes was examined using current-voltage-temperature, turn-on voltage-temperature, and series resistance-temperature measurements. The thermal coefficient ( K j ) and characteristic temperature ( T 0 ) at T ? 293 K were determined to be -4.1 mV/K and 65.06 K, respectively. The effective Schottky barrier height (SBH) was also determined to be 2.1 (±0.03) eV, which was in good agreement with the theoretical value. The possible carrier transport mechanisms at the interface are described in terms of the thermally decreased energy-band gap of p-GaN layers, thermally increased deep-level acceptor and increased further-activated-shallow-level acceptor. These were confirmed by the thermally increased ideality factor and high tunnelling parameter.

  10. 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 ?M. 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

  11. Charge carrier transport mechanisms in perovskite CdTiO3 fibers

    Science.gov (United States)

    Imran, Z.; Rafiq, M. A.; Hasan, M. M.

    2014-06-01

    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.

  12. 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.

  13. 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

  14. 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

  15. Uptake and transport mechanisms of decabromodiphenyl ether (BDE-209) by rice (Oryza sativa).

    Science.gov (United States)

    Chow, Ka Lai; Man, Yu Bon; Tam, Nora Fung Yee; Liang, Yan; Wong, Ming Hung

    2015-01-01

    The extensive industrial use of brominated flame retardants has aroused rapidly growing public concerns about their ubiquity in the environment. The feasibility of uptake and translocation of decabromodiphenyl ether (BDE-209) by three rice cultivars, namely Fengmeizhan, Hefengzhan and Guangyinzhan, and the uptake mechanisms of BDE-209 into rice roots, were investigated by employing a partition-limited model. Uptake of BDE-209 by the rice cultivars (Fengmeizhan, Hefengzhan and Guangyinzhan) was examined by a 60-day cultivation in sterilized BDE-209 spiked sand, followed by Soxhlet extraction and gas chromatography-mass spectrometry (GC-MS) analysis. A partition-limited model was applied for estimating and describing the approach of the uptake of BDE-209 by rice in sand. The average quasi-equilibrium factor (?pt) of BDE-209 in root uptake in sand was 0.112×10(-3) for three rice cultivars in the present study (<1), implying a non-equilibrium movement of molecules and a dominated passive transport uptake. According to the results of sorption analysis of dead and fresh roots, apoplastic pathway likely dominated the transport of BDE-209 into roots cells. PMID:25460770

  16. 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.

  17. Mass transport mechanism of cu species at the metal/dielectric interfaces with a graphene barrier.

    Science.gov (United States)

    Zhao, Yuda; Liu, Zhaojun; Sun, Tieyu; Zhang, Ling; Jie, Wenjing; Wang, Xinsheng; Xie, Yizhu; Tsang, Yuen Hong; Long, Hui; Chai, Yang

    2014-12-23

    The interface between the metal and dielectric is an indispensable part in various electronic devices. The migration of metallic species into the dielectric can adversely affect the reliability of the insulating dielectric and can also form a functional solid-state electrolyte device. In this work, we insert graphene between Cu and SiO2 as a barrier layer and investigate the mass transport mechanism of Cu species through the graphene barrier using density functional theory calculations, second-ion mass spectroscopy (SIMS), capacitance-voltage measurement, and cyclic voltammetry. Our theoretical calculations suggest that the major migration path for Cu species to penetrate through the multiple-layered graphene is the overlapped defects larger than 0.25 nm2. The depth-profile SIMS characterizations indicate that the "critical" thickness of the graphene barrier for completely blocking the Cu migration is 5 times smaller than that of the conventional TaN barrier. Capacitance-voltage and cyclic voltammetry measurement reveal that the electrochemical reactions at the Cu/SiO2 interface become a rate-limiting factor during the bias-temperature stressing process with the use of a graphene barrier. These studies provide a distinct roadmap for designing controllable mass transport in solid-state electrolyte devices with the use of a graphene barrier. PMID:25423484

  18. Dual Mechanisms of Metabolite Acquisition by the Obligate Intracytosolic Pathogen Rickettsia prowazekii Reveal Novel Aspects of Triose Phosphate Transport

    OpenAIRE

    Frohlich, Kyla M.; Audia, Jonathon P.

    2013-01-01

    Rickettsia prowazekii is an obligate intracytosolic pathogen and the causative agent of epidemic typhus fever in humans. As an evolutionary model of intracellular pathogenesis, rickettsiae are notorious for their use of transport systems that parasitize eukaryotic host cell biochemical pathways. Rickettsial transport systems for substrates found only in eukaryotic cell cytoplasm are uncommon among free-living microorganisms and often possess distinctive mechanisms. We previously reported that...

  19. 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.

  20. ADSORPTION MECHANISMS AND TRANSPORT BEHAVIOR BETWEEN SELENATE AND SELENITE ON DIFFERENT SORBENTS

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, Michelle MV; Um, Wooyong

    2014-04-30

    Adsorption of different oxidation species of selenium (Se), selenate (SeO42-) and selenite (SeO32-), with varying pHs (2 - 10) and ionic strengths (I = 0.01 M, 0.1 M and 1.0 M NaNO3) was measured on quartz, aluminum oxide, and synthetic iron oxide (ferrihydrite) using batch reactors to obtain a more detailed understanding of the adsorption mechanisms (e.g., inner- and outer-sphere complex). In addition to the batch experiments with single minerals contained in native Hanford Site sediment, additional batch adsorption studies were conducted with native Hanford Site sediment and groundwater as a function of 1) total Se concentration (from 0.01 to 10 mg L-1) and 2) soil to solution ratios (1:20 and 1:2 grams per mL). Results from these batch studies were compared to a set of saturated column experiments that were conducted with natural Hanford sediment and groundwater spiked with either selenite or selenate to observe the transport behavior of these species. Both batch and column results indicated that selenite adsorption was consistently higher than that of selenate in all experimental conditions used. These different adsorption mechanisms between selenite and selenate result in the varying mobility of Se in the subsurface environment and explain the dependence on the oxidation species.

  1. An alkaline phosphatase transport mechanism in the pathogenesis of Alzheimer's disease and neurodegeneration.

    Science.gov (United States)

    Pike, Adrianne F; Kramer, Nynke I; Blaauboer, Bas J; Seinen, Willem; Brands, Ruud

    2015-01-25

    Systemic inflammation is associated with loss of blood-brain barrier integrity and neuroinflammation that lead to the exacerbation of neurodegenerative diseases. It is also associated specifically with the characteristic amyloid-? and tau pathologies of Alzheimer's disease. We have previously proposed an immunosurveillance mechanism for epithelial barriers involving negative feedback-regulated alkaline phosphatase transcytosis as an acute phase anti-inflammatory response that hangs in the balance between the resolution and the progression of inflammation. We now extend this model to endothelial barriers, particularly the blood-brain barrier, and present a literature-supported mechanistic explanation for Alzheimer's disease pathology with this system at its foundation. In this mechanism, a switch in the role of alkaline phosphatase from its baseline duties to a stopgap anti-inflammatory function results in the loss of alkaline phosphatase from cell membranes into circulation, thereby decreasing blood-brain barrier integrity and functionality. This occurs with impairment of both amyloid-? efflux and tau dephosphorylating activity in the brain as alkaline phosphatase is replenished at the barrier by receptor-mediated transport. We suggest systemic alkaline phosphatase administration as a potential therapy for the resolution of inflammation and the prevention of Alzheimer's disease pathology as well as that of other inflammation-related neurodegenerative diseases. PMID:25500268

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

    Science.gov (United States)

    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

  3. 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

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

    Science.gov (United States)

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

    2012-12-01

    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 within 3% in zonal mean monthly averages. In addition, the tagged ozone is shown to equal the standard ozone, when all tropospheric sources are tagged and stratospheric input is turned off. The stratospheric ozone contribution to the troposphere determined from the difference between total ozone and ozone from all tagged sources is significantly less than estimates using a traditional stratospheric ozone tracer (8 vs. 20 ppbv at the surface). The commonly used technique of perturbing NO emissions by 20% in a region to determine its ozone contribution is compared to the tagging technique, showing that the tagged ozone is 2-4 times the ozone contribution that was deduced from perturbing emissions. The ozone tagging described here is useful for identifying source contributions based on NO emissions in a given state of the atmosphere, such as for quantifying the ozone budget.

  5. Cellular mechanism of HCO-3 and Cl- transport in insect salt gland.

    Science.gov (United States)

    Strange, K; Phillips, J E

    1985-01-01

    Active HCO-3 secretion in the anterior rectal salt gland of the mosquito larva, Aedes dorsalis, is mediated by a 1:1 Cl-/HCO-3 exchanger. The cellular mechanisms of HCO-3 and Cl- transport are examined using ion- and voltage-sensitive microelectrodes in conjunction with a microperfused preparation which allowed rapid saline changes. Addition of DIDS or acetazolamide to, or removal of CO2 and HCO-3 from, the serosal bath caused large (20 to 50 mV) hyperpolarizations of apical membrane potential (Va) and had little effect on basolateral potential (Vbl). Changes in luminal Cl- concentration altered Va in a rapid, linear manner with a slope of 42.2 mV/decalog a1Cl-. Intracellular Cl- activity was 23.5 mM and was approximately 10 mM lower than that predicted for a passive distribution across the apical membrane. Changes in serosal Cl- concentration had no effect on Vbl, indicating an electrically silent basolateral Cl- exit step. Intracellular pH in anterior rectal cells was 7.67 and the calculated acHCO-3 was 14.4 mM. These results show that under control conditions HCO-3 enters the anterior rectal cell by an active mechanism against an electrochemical gradient of 77.1 mV and exits the cell at the apical membrane down a favorable electrochemical gradient of 27.6 mV. A tentative cellular model is proposed in which Cl- enters the apical membrane of the anterior rectal cells by passive, electrodiffusive movement through a Cl- -selective channel, and HCO-3 exits the cell by an active or passive electrogenic transport mechanism. The electrically silent nature of basolateral Cl- exit and HCO-3 entry, and the effects of serosal addition of the Cl-/HCO-3 exchange inhibitor, DIDS, on JCO2net and transepithelial potential (Vte) suggest strongly that the basolateral membrane is the site of a direct coupling between Cl- and HCO-3 movements. PMID:3999119

  6. Charge carrier transport mechanisms in perovskite CdTiO{sub 3} fibers

    Energy Technology Data Exchange (ETDEWEB)

    Imran, Z.; Rafiq, M. A., E-mail: aftab@cantab.net; Hasan, M. M. [Micro and Nano Devices Group, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), P.O. Nilore, Islamabad, 45650 (Pakistan)

    2014-06-15

    Electrical transport properties of electrospun cadmium titanate (CdTiO{sub 3}) 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 N{sub t} = 6.27 × 10{sup 17} /cm{sup 3}. 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(E{sub F}) = 5.51 × 10{sup 21} eV{sup ?1} cm{sup ?3} at 2 V. Other VRH parameters such as hopping distance (R{sub hop}) and hopping energy (W{sub hop}) 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 CdTiO{sub 3} fibers efficient material for capacitive energy storage devices.

  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. Paddle-wheel versus percolation mechanism for cation transport in some sulphate phases

    DEFF Research Database (Denmark)

    Andersen, N.H.; Bandaranyake, P.W.S.K.

    1992-01-01

    Lithium sulphate and a few other compounds have high temperature phases which are both solid electrolytes and plastic crystals (rotor phases). Three types of experiments are here considered in order to test the validity of a "paddle-wheel mechanism" that has been proposed for cation conductivity in these phases. A single-crystal neutron diffraction study has been performed for cubic lithium sulphate. The refinement of the data gives a very complex model for the location of the lithium ions. There is definitely a void at and near the octahedral (1/2, 1/2, 1/2) position. 90% of the lithium ions are located at the tetrahedral 8c-sites (1/4, 1/4, 1/4), although significantly distorted in the directions of the four neighbouring sulphate ions. The remaining 10% of the lithium ions are refined as an evenly distributed spherical shell which is surrounding the sulphate ions. The lithium ions are 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 lithium sulphate. The conductivity is reduced in the one-phase region, while it is increased in a two phase (solid-melt) region. There are pronounced differences between the rotor phases and other phases concerning how partial cation substitution affects the electrical conductivity of solid solutions. Regarding self and interdiffusion, all studied mono- and divalent cations are very mobile in the rotor phases, which lack the pronounced correlation with ionic radii that is characteristic for diffusion in other classes of solid electrolytes. The quoted studies are to be considered as strong evidence against a percolation model proposed by Secco.

  9. Study on transportation and accumulation mechanisms of cesium in Camellia sinensis by SR-XRF imaging

    International Nuclear Information System (INIS)

    After the tragedy in Fukushima, soil and food pollution by radionuclides has become a serious problem. Cs can be uptaken by many plants due to its chemical similarities with K. So, removal of radioactive Cs from the soils can be carried out using the phytoremediation technology. However, the development of phytoremediation techniques require the knowledge on the interactions between the plants and soils. Although the competitive relation between K and Cs to enter the plant is known, few works were dedicated to the visual localization of Cs in the plant and its relation to potassium. In this study, we have used synchrotron radiation X-ray fluorescence (SR-XRF) imaging in order to reveal accumulation of Cs with a cellular spatial resolution. The Cs L? intensity measured in the XRF imaging were transformed into the Cs concentration based on the calibration curves prepared using in house standard samples of known Cs concentrations. It is remarkable that after exposure to 10 ppm Cs solution for 4 weeks Camellia sinensis accumulated Cs up to 300 ppm (expressed in dry weight) in the body. XRF imaging of the root show that Cs was located mainly at the epidermis. On the other hand, K was located mainly at endodermis and the cell wall. A correlation coefficient(R) between XRF intensity of K and that of Cs in the root was about R=0.5. This suggest that Cs is hardly absorbed from roots of Camellia sinensis compared with K, due to its large ionic radius. In the case of stem, distribution of Cs was similar to that of K. They were located at the exodermis, epidermis and the cell wall. Their correlation coefficient was about R=0.8. These results suggest that Cs was transported through the same pathway as that of K in the stem. (author)

  10. Fibre bundle formulation of nonrelativistic quantum mechanics; 4, Mixed states and evolution transport's curvature

    CERN Document Server

    Iliev, Bozhidar Z

    1999-01-01

    We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one but it is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it a pure state of some quantum system is described by a state section (along paths) of a (Hilbert) fibre bundle. It's evolution is determined through the bundle (analogue of the) Schrödinger equation. Now the dynamical variables and the density operator are described via bundle morphisms (along paths). The mentioned quantities are connected by a number of relations derived in this work. The present fourth part of this series is devoted mainly to the fibre bundle description of mixed quantum states. We show that to the conventional density operator there corresponds a unique density morphism (along paths) for which the corresponding equations of motion are derived. It is also investigated the bundle description of mixed quantu...

  11. 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.

  12. 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

  13. Structural, mechanical and magnetic properties studies on high-energy Kr-ion irradiated Fe3O4 material (main corrosion layer of Fe-based alloys)

    Science.gov (United States)

    Sun, Jianrong; Wang, Zhiguang; Zhang, Hongpeng; Song, Peng; Chang, Hailong; Cui, Minghuan; Pang, Lilong; Zhu, Yabin; Li, Fashen

    2014-12-01

    The Fe-based (T91 and RAFM) alloys are considered as the promising candidate structural materials for DEMO and the first fusion power plant, and these two kinds of steels suffered more serious corrosion attack at 450 °C in liquid PbBi metal. So in order to further clarify the applicability of Fe-based structural materials in nuclear facilities, we should study not only the alloys itself but also its corrosion layers; and in order to simplify the discussion and clarify the irradiation effects of the different corrosion layer, we abstract the Fe3O4 (main corrosion layer of Fe-based alloys) to study the structural, micro-mechanical and magnetic properties under 2.03 GeV Kr-ion irradiation. The initial crystallographic structure of the Fe3O4 remains unaffected after irradiation at low damage levels, but as the Kr-ion fluence increases and the defects accumulate, the macroscopic magnetic properties (Ms, Hc, etc.) and micro-mechanical properties (nano-hardness and Young's modulus) are sensitive to high-energy Kr-ion irradiation and exhibit excruciating uniform changing regularities with varying fluences (firstly increases, then decreases). And these magnetism, hardening and softening phenomena can be interpreted very well by the effects related to the stress and defects (the production, accumulation and free) induced by high-energy ions irradiation.

  14. Current-transport mechanism in Au/V-doped PVC+TCNQ/p-Si structures

    Science.gov (United States)

    Tecimer, H.; Vural, Ö.; Kaya, A.; Alt?ndal, ?.

    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) (?ap = ?Bo) and ideality factor (nap = n) were found strongly temperature dependent and the value of nap decreases, while the ?ap increases with the increasing temperature. Also, the ?ap 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 (?Si = -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 ?ap and nap with temperature, ?ap Versus q/2kT plot was drawn and the mean value of (?Bo) and standard deviation (?s) 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)-(q?s)2/2(kT)2 versus (q/kT) plot gives the ?Bo and effective Richardson constant A* as 1.115 eV and 31.94 A?(cm?K)-2, respectively. This value of A*( = 31.94 A?(cm?K)-2) is very close to the theoretical value of 32 A?(cm?K)-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.

  15. Avaliação de mecânica ventilatória por oscilações forçadas: fundamentos e aplicações clínicas Analysis of the ventilatory mechanics by forced oscillations technique: main concepts and clinical applications

    Directory of Open Access Journals (Sweden)

    PEDRO LOPES DE MELO

    2000-08-01

    Full Text Available Requerendo apenas cooperação passiva e fornecendo novos parâmetros para análise da mecânica ventilatória, a técnica de oscilações forçadas (TOF apresenta características complementares aos métodos clássicos de avaliação pulmonar. Neste trabalho, inicialmente é apresentada uma revisão dos princípios da técnica juntamente com uma discussão sobre suas vantagens e atuais limitações. A performance da técnica é comparada com a dos métodos clássicos na detecção de afecções respiratórias. As principais aplicações clínicas reportadas anteriormente na literatura, incluindo a avaliação da mecânica ventilatória infantil, estudos em neonatos, monitorização de pacientes sob ventilação mecânica, medicina ocupacional e avaliação de distúrbios no sono, são revisadas e discutidas. Com base na revisão efetuada e nos resultados obtidos em estudos efetuados em laboratório, os autores concluem que a TOF pode contribuir para um exame mais detalhado, assim como para facilitar a realização de testes de função pulmonar em condições nas quais as técnicas tradicionais não são adequadas.Requesting passive cooperation from the patient and supplying new parameters for the analysis of the ventilatory mechanics, the forced oscillations technique (FOT has complementary characteristics to the classical methods of lung evaluation. In this work, a review of the principles of this technique is initially presented together with a discussion about its advantages and present limitations. The performance of the technique is compared to classical methods in the detection of breathing disorders. The main clinical applications reported previously in the literature, including the evaluation of the ventilatory mechanics in children, studies in neonates, monitoring of patients under mechanical ventilation, occupational medicine, and evaluation of respiratory sleep disturbances are reviewed and discussed. Based on this review and on the results obtained in studies made in their laboratory, the authors concluded that FOT could render a more detailed examination and facilitate the accomplishment of lung function tests under conditions in which traditional techniques are not appropriate.

  16. Avaliação de mecânica ventilatória por oscilações forçadas: fundamentos e aplicações clínicas / Analysis of the ventilatory mechanics by forced oscillations technique: main concepts and clinical applications

    Scientific Electronic Library Online (English)

    PEDRO LOPES DE, MELO; MARCELO MARTINS, WERNECK; ANTONIO, GIANNELLA-NETO.

    2000-08-01

    Full Text Available Requerendo apenas cooperação passiva e fornecendo novos parâmetros para análise da mecânica ventilatória, a técnica de oscilações forçadas (TOF) apresenta características complementares aos métodos clássicos de avaliação pulmonar. Neste trabalho, inicialmente é apresentada uma revisão dos princípios [...] da técnica juntamente com uma discussão sobre suas vantagens e atuais limitações. A performance da técnica é comparada com a dos métodos clássicos na detecção de afecções respiratórias. As principais aplicações clínicas reportadas anteriormente na literatura, incluindo a avaliação da mecânica ventilatória infantil, estudos em neonatos, monitorização de pacientes sob ventilação mecânica, medicina ocupacional e avaliação de distúrbios no sono, são revisadas e discutidas. Com base na revisão efetuada e nos resultados obtidos em estudos efetuados em laboratório, os autores concluem que a TOF pode contribuir para um exame mais detalhado, assim como para facilitar a realização de testes de função pulmonar em condições nas quais as técnicas tradicionais não são adequadas. Abstract in english Requesting passive cooperation from the patient and supplying new parameters for the analysis of the ventilatory mechanics, the forced oscillations technique (FOT) has complementary characteristics to the classical methods of lung evaluation. In this work, a review of the principles of this techniqu [...] e is initially presented together with a discussion about its advantages and present limitations. The performance of the technique is compared to classical methods in the detection of breathing disorders. The main clinical applications reported previously in the literature, including the evaluation of the ventilatory mechanics in children, studies in neonates, monitoring of patients under mechanical ventilation, occupational medicine, and evaluation of respiratory sleep disturbances are reviewed and discussed. Based on this review and on the results obtained in studies made in their laboratory, the authors concluded that FOT could render a more detailed examination and facilitate the accomplishment of lung function tests under conditions in which traditional techniques are not appropriate.

  17. Carrier transport mechanisms of hybrid ZnO nanorod-polymer LEDs

    Science.gov (United States)

    Cho, Sungjae; Lee, Kyu Seung; Son, Dong Ick; Oh, Youngjei; Choi, Won Kook; Angadi, Basavaraj

    2014-07-01

    A hybrid polymer-nanorod (NR) light-emitting diode (LED), consisting of a hole-conducting polymer poly (9-vinyl carbazole) (PVK) and ZnO nanorod (NR) composite, with the device structure of glass/indium-tin-oxide (ITO)/PEDOT:PSS/(PVK + ZnO nanorods)/Al is fabricated through a simple spin coating technique. TEM images shows inhomogeneous deposition and the agglomeration of ZnO NRs, which is explained through their low probability of adsorption on PVK due to two-dimensional structural property. In the current-voltage characteristics, negative differential resistance (NDR) phenomenon is observed corresponding to device structure without ZnO NRs. The carrier transport behavior in the LED device is well described by both ohmic and space-chargelimited-current (SCLC) mechanisms. Broad blue electroluminescence (EL) consisting of two sub peaks, are centered at 441 nm and the other at 495 nm, is observed, which indicates that the ZnO nanorod play a role as a recombination center for excitons. The red shift in the position of the EL compared to that photoluminescence is well explained through band offsets at the heterojunction between the PVK and ZnO NRs.

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

    International Nuclear Information System (INIS)

    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 132Sn 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 effects. Observables sensitive to the isospin dependent part of nuclear interaction are discussed, providing information on the symmetry energy density dependence below saturation.

  19. Carrier transport mechanisms of hybrid ZnO nanorod-polymer LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sungjae; Lee, Kyuseung; Son, Dongick [Korea Institute of Science and Technology, Wanju (Korea, Republic of); Oh, Youngjei; Choi, Wonkook [Korea Institute of Science and Technology, Seoul (Korea, Republic of); Angadi, Basavaraj [Bangalore University, Bangalore (India)

    2014-07-15

    A hybrid polymer-nanorod (NR) light-emitting diode (LED), consisting of a hole-conducting polymer poly (9-vinyl carbazole) (PVK) and ZnO nanorod (NR) composite, with the device structure of glass/indium-tin-oxide (ITO)/PEDOT:PSS/(PVK + ZnO nanorods)/Al is fabricated through a simple spin coating technique. TEM images shows inhomogeneous deposition and the agglomeration of ZnO NRs, which is explained through their low probability of adsorption on PVK due to two-dimensional structural property. In the current-voltage characteristics, negative differential resistance (NDR) phenomenon is observed corresponding to device structure without ZnO NRs. The carrier transport behavior in the LED device is well described by both ohmic and space-charge-limited-current (SCLC) mechanisms. Broad blue electroluminescence (EL) consisting of two sub peaks, are centered at 441 nm and the other at 495 nm, is observed, which indicates that the ZnO nanorod play a role as a recombination center for excitons. The red shift in the position of the EL compared to that photoluminescence is well explained through band offsets at the heterojunction between the PVK and ZnO NRs.

  20. Carrier transport mechanisms of hybrid ZnO nanorod-polymer LEDs

    International Nuclear Information System (INIS)

    A hybrid polymer-nanorod (NR) light-emitting diode (LED), consisting of a hole-conducting polymer poly (9-vinyl carbazole) (PVK) and ZnO nanorod (NR) composite, with the device structure of glass/indium-tin-oxide (ITO)/PEDOT:PSS/(PVK + ZnO nanorods)/Al is fabricated through a simple spin coating technique. TEM images shows inhomogeneous deposition and the agglomeration of ZnO NRs, which is explained through their low probability of adsorption on PVK due to two-dimensional structural property. In the current-voltage characteristics, negative differential resistance (NDR) phenomenon is observed corresponding to device structure without ZnO NRs. The carrier transport behavior in the LED device is well described by both ohmic and space-charge-limited-current (SCLC) mechanisms. Broad blue electroluminescence (EL) consisting of two sub peaks, are centered at 441 nm and the other at 495 nm, is observed, which indicates that the ZnO nanorod play a role as a recombination center for excitons. The red shift in the position of the EL compared to that photoluminescence is well explained through band offsets at the heterojunction between the PVK and ZnO NRs.

  1. Mechanisms and dynamics of the external transport barrier formation in non-linear plasma edge simulations

    Science.gov (United States)

    Chôné, L.; Beyer, P.; Sarazin, Y.; Fuhr, G.; Bourdelle, C.; Benkadda, S.

    2015-07-01

    L-H transition features are reproduced using three-dimensional first-principles plasma edge turbulence simulations. A transport barrier is observed to form spontaneously above a threshold of the input power. The physical mechanism relies on the coupling between the equilibrium pressure gradient and the poloidal flow, through both the radial force balance and the neoclassical friction. Accounting for the actual radial profile and time evolution of the latter is key to the barrier formation. It is found that neoclassical friction acts as an energy source for the flow, which largely overcomes the sink due to the turbulent Reynolds stress during the whole barrier lifetime. Importantly, experimentally reported dynamical features are recovered during the formation and lifetime of the barrier. This includes dithering of the radial electric field, which is reminiscent of experimentally observed limit-cycle oscillations and quasi-periodic relaxation oscillations showing similarities with type-III ELMs. These rich dynamics emerge from interplay between turbulence, turbulence-driven flows and the equilibrium flow governed by force balance.

  2. Evaluation of potential sources and transport mechanisms of fecal indicator bacteria to beach water, Murphy Park Beach, Door County, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Corsi, Steven R.; McDermott, Colleen; Kleinheinz, Gregory; Fogarty, Lisa R.; Haack, Sheridan K.; Johnson, Heather E.

    2013-01-01

    Fecal Indicator Bacteria (FIB) concentrations in beach water have been used for many years as a criterion for closing beaches due to potential health concerns. Yet, current understanding of sources and transport mechanisms that drive FIB occurrence remains insufficient for accurate prediction of closures at many beaches. Murphy Park Beach, a relatively pristine beach on Green Bay in Door County, Wis., was selected for a study to evaluate FIB sources and transport mechanisms. Although the relatively pristine nature of the beach yielded no detection of pathogenic bacterial genes and relatively low FIB concentrations during the study period compared with other Great Lakes Beaches, its selection limited the number of confounding FIB sources and associated transport mechanisms. The primary sources of FIB appear to be internal to the beach rather than external sources such as rivers, storm sewer outfalls, and industrial discharges. Three potential FIB sources were identified: sand, swash-zone groundwater, and Cladophora mats. Modest correlations between FIB concentrations in these potential source reservoirs and FIB concentrations at the beach from the same day illustrate the importance of understanding transport mechanisms between FIB sources and the water column. One likely mechanism for transport and dispersion of FIB from sand and Cladophora sources appears to be agitation of Cladophora mats and erosion of beach sand due to storm activity, as inferred from storm indicators including turbidity, wave height, current speed, wind speed, sky visibility, 24-hour precipitation, and suspended particulate concentration. FIB concentrations in beach water had a statistically significant relation (p-value ‹0.05) with the magnitude of these storm indicators. In addition, transport of FIB in swash-zone groundwater into beach water appears to be driven by groundwater recharge associated with multiday precipitation and corresponding increased swash-zone groundwater discharge at the beach, as indicated by an increase in the specific conductance of beach water. Understanding the dynamics of FIB sources (sand, swash-zone groundwater, and Cladophora) and transport mechanisms (dispersion and erosion from storm energy, and swash-zone groundwater discharge) is important for improving predictions of potential health risks from FIB in beach water.

  3. 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

  4. Ocean heat transport in a simple ocean data assimilation (SODA): Structure, mechanisms, and impacts on climate

    Science.gov (United States)

    Zheng, Yangxing

    A Simple Ocean Data Assimilation (SODA) reanalysis is used to investigate the trend and variability of global ocean heat transport for the period 1958-2004. The forecast model utilizes Parallel Ocean Program (POP) physics, with an average 0.4° (lon) x 0.25° (lat) x 40-level resolution, and is forced with ERA-40 atmospheric reanalysis from 1958 to 2001. The reanalysis is updated in a second run which is forced with QuickSCAT wind stress from 2000 to 2004. SODA uses a sequential estimation algorithm, with observations from the historical archive of hydrographic profiles supplemented by ship intake measurements, moored hydrographic observations and remotely sensed sea surface temperature. The results suggest that the interannual to decadal variability of ocean heat transport (OHT) is primarily controlled by the strength of the meridional overturning circulation (MOC), particularly in the Atlantic Ocean. The role of variation of temperature on variability of meridional OHT increases in the northern North Atlantic Ocean. Results from an analysis of the vertical structure of OHT show that most change of OHT in the oceans occurs in the upper 1000m. A heat budget analysis for the North Atlantic Ocean suggests that the long-term change of surface heat flux is principally balanced by the convergence of OHT as compared to change in the heat storage. The linear change in heat storage rate is only about one third as large as the convergence of OHT. Enhanced subtropical cells (STCs), largely affected by strengthened equatorial upwelling processes, are responsible for an intensified northward OHT in the north tropical Atlantic Ocean and a weakened northward OHT in the south tropical Atlantic Ocean. Convergence of flow due to a northward shift of the atmospheric circulation in the mid-latitude Atlantic reinforces the MOCs, which contribute to a positive trend of OHT. Finally, in the northern North Atlantic Ocean, a small increase in meridional OHT and a slight weakening of MOC are detected. The weakening in the northern North Atlantic MOC mainly arises from a freshening in the Labrador Sea and slowdown of the overflows from the Nordic Seas into the northern North Atlantic Ocean.

  5. 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)

  6. “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

  7. CBM and CO{sub 2}-ECBM related coupled transport- and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Gensterblum, Y.; Satorius, M.; Krooss, B.M. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Busch, A. [Shell Global Solutions International, Rijswijk (Netherlands)

    2013-08-01

    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 (CH{sub 4}, CO{sub 2}) and inert gases (N{sub 2}, 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 (c{sub f}) 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 (c{sub f}) 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. These observations have been summarised to a best practice for the operation of a CBM reservoir. This contains for instance a permeability development as a function of reservoir pressure. (orig.)

  8. 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

    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 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 mechani...

  9. Molecular mechanism of ?-tocopheryl-phosphate transport across the cell membrane

    International Nuclear Information System (INIS)

    ?-Tocopheryl-phosphate (?-TP) is synthesized and hydrolyzed in animal cells and tissues where it modulates several functions. ?-TP is more potent than ?-T in inhibiting cell proliferation, down-regulating CD36 transcription, inhibiting atherosclerotic plaque formation. Administration of ?-TP to cells or animals requires its transfer through membranes, via a transporter. We show here that ?-TP is passing the plasma membrane via a system that is inhibited by glibenclamide and probenecid, inhibitors of a number of transporters. Glibenclamide and probenecid prevent dose-dependently ?-TP inhibition of cell proliferation. The two inhibitors act on ATP binding cassette (ABC) and organic anion transporters (OAT). Since ABC transporters function to export solutes and ?-TP is transported into cells, it may be concluded that ?-TP transport may occur via an OAT family member. Due to the protection by glibenclamide and probenecid on the ?-TP induced cell growth inhibition it appears that ?-TP acts after its uptake inside cells

  10. 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.)

  11. The role of biomembrane lipids in the molecular mechanism of ion transport radiation damage

    International Nuclear Information System (INIS)

    Increase in the rate of ATP synthesis (I.4-I.6 times), Ca2+-capacity (I.4-I.8 times), membrane potential (by 20-50 mv) and decrease in K--conductivity (2.5-3 times) in rat liver mitochondria was observed three hours after ?-irradiation at a dose of 1000r. The process of oxidative phosphorylation was normalized 24 hours later, whereas damages of Ca2+-accumulation and K+-conductivity remain. The molecular mechanism of reduction in K+-permeability of mitochondrial membranes has been studied. The endogenous regulators of ionic transport in the lipid phase of mitochondrial biomembranes were investigated before and after ?-irradiation. It was revealed that K+-conductivity of the artificial phospholipid membranes (APM) formed of the phospholipids from irradiated mitochondria was substantially lower than that in the control. Using thin-layer chromatography the minor phospholipid fraction which increases K+-conductivity of APM was isolated from the lipids of unirradiated mitochondria. In the lipid preparations of irradiated mitochondria the minor phospholipid fraction content is sharply lowered (or absent at all). Besides the content of lysoforms of phosphatidylcholine and phosphatidylethanolamine as well as that of fatty acids and cholesterol esters were reduced 24 hours after irradiation. Three compounds with different capability to increase the APM conductivity for monovalent ions were revealed in the composition of the minor fraction. One of these components was shown to be lysopolyglycerophosphatide (lysodiphosphatidylglycerol). The role of the enzyme systems involved in radiational changes of the membrane lipid components and the importance of these phenomena for cell radiosensitivity will be discussed

  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. Electric vehicles and renewable energy in the transport sector - energy system consequences. Main focus: Battery electric vehicles and hydrogen based fuel cell vehicles

    DEFF Research Database (Denmark)

    Nielsen, L.H.; JØrgensen K., no-firstname

    2000-01-01

    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 toillustrate 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 liberalisedelectricity 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 forthe 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 analysisincludes 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. Theelectricity 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 potentialtransition 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 powersupply 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 baselineelectricity 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 tothe Norwegian model.

  14. 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 ?m and 0.525 ?m. 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.

  15. The cytotoxicity of the ?1-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 ?1-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-?-cyclodextrin (cholesterol chelator) inhibited the uptake of QAPB. Bafilomycin A1 and methyl-?-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

  16. Study of mechanical and thermal transport properties of Cis- and Trans-polyisoprene blends in low temperature range

    Science.gov (United States)

    Baboo, Mahesh; Sharma, Kananbala; Saxena, N. S.

    2014-10-01

    Measurements of mechanical and thermal transport properties have been carried out on the samples of polyisoprene (Cis and Trans) blends prepared by solution casting, in the temperature range from 173K to 273K using Dynamic Mechanical Analyzer and Transient Plane Source Technique, respectively. Results show that a sudden change is observed in the values of tan ?, storage modulus (G), thermal conductivity (?) and heat capacity per unit volume (?cp) at the glass transition temperature. Also the values of G, ? and ?cp have been observed higher for all the three blends as compared to their pure components. The variation of all these properties has been explained on the basis of crystallinity and crosslink density.

  17. Mechanisms controlling surface ozone over East Asia: a multiscale study coupling regional and global chemical transport models

    OpenAIRE

    Lin, M.; HOLLOWAY, T; Oki, T.; Streets, D. G.; Richter, A.

    2008-01-01

    Mechanisms controlling surface ozone (O3) over East Asia are examined using the regional Community Multiscale Air Quality (CMAQ) model at two horizontal scales: 81 km and 27 km. Through sensitivity studies and comparison with recently available satellite data and surface measurements in China and Japan, we find that the O3 budget over East Asia shows complex interactions among photochemical production, regional transport, meteorological conditions...

  18. Adenoviral-Mediated Placental Gene Transfer of IGF-1 Corrects Placental Insufficiency via Enhanced Placental Glucose Transport Mechanisms

    OpenAIRE

    Jones, Helen N.; Crombleholme, Timothy; Habli, Mounira

    2013-01-01

    Previous work in our laboratory demonstrated that over-expression of human insulin-like growth factor -1 (hIGF-1) in the placenta corrects fetal weight deficits in mouse, rat, and rabbit models of intrauterine growth restriction without changes in placental weight. The underlying mechanisms of this effect have not been elucidated. To investigate the effect of intra-placental IGF-1 over-expression on placental function we examined glucose transporter expression and localization in both a mouse...

  19. Metaiodobenzylguanidine [131I] scintigraphy detects impaired myocardial sympathetic neuronal transport function of canine mechanical-overload heart failure

    International Nuclear Information System (INIS)

    In heart failure secondary to chronic mechanical overload, cardiac sympathetic neurons demonstrate depressed catecholamine synthetic and transport function. To assess the potential of sympathetic neuronal imaging for detection of depressed transport function, serial scintigrams were acquired after the intravenous administration of metaiodobenzylguanidine [131I] to 13 normal dogs, 3 autotransplanted (denervated) dogs, 5 dogs with left ventricular failure, and 5 dogs with compensated left ventricular hypertrophy due to a surgical arteriovenous shunt. Nine dogs were killed at 14 hours postinjection for determination of metaiodobenzylguanidine [131I] and endogenous norepinephrine content in left atrium, left ventricle, liver, and spleen. By 4 hours postinjection, autotransplanted dogs had a 39% reduction in mean left ventricular tracer accumulation, reflecting an absent intraneuronal tracer pool. Failure dogs demonstrated an accelerated early mean left ventricular tracer efflux rate (26.0%/hour versus 13.7%/hour in normals), reflecting a disproportionately increased extraneuronal tracer pool. They also showed reduced late left ventricular and left atrial concentrations of tracer, consistent with a reduced intraneuronal tracer pool. By contrast, compensated hypertrophy dogs demonstrated a normal early mean left ventricular tracer efflux rate (16.4%/hour) and essentially normal late left ventricular and left atrial concentrations of tracer. Metaiodobenzylguanidine [131I] scintigraphic findings reflect the integrity of the cardiac sympathetic neuronal transport system in canine mechanical-overload heart failure. Metaiodobenzylguanidine [123I] scintigraphy should be explored as a means of early detection of mechanical-overload heart failure in patients

  20. 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)

  1. The transport mechanism of the human sodium/myo-inositol transporter 2 (SMIT2/SGLT6), a member of the LeuT structural family.

    Science.gov (United States)

    Sasseville, Louis J; Longpré, Jean-Philippe; Wallendorff, Bernadette; Lapointe, Jean-Yves

    2014-09-01

    The sodium/myo-inositol transporter 2 (SMIT2) is a member of the SLC5A gene family, which is believed to share the five-transmembrane segment inverted repeat of the LeuT structural family. The two-electrode voltage-clamp (TEVC) technique was used to measure the steady-state and the pre-steady-state currents mediated by human SMIT2 after expression in Xenopus laevis oocytes. Phlorizin is first shown to be a poor inhibitor of pre-steady-state currents for depolarizing voltage pulse. From an up to threefold difference between the apparent ON and OFF transferred charges during a voltage pulse, we also show that a fraction of the transient current recorded for very negative potentials is not a true pre-steady-state current coming from the cotransporter conformational changes. We suggest that this transient current comes from a time-dependent leak current that can reach large amplitudes when external Na(+) concentration is reduced. A kinetic model was generated through a simulated annealing algorithm. This algorithm was used to identify the optimal connectivity among 19 different kinetic models and obtain the numerical values of the associated parameters. The proposed 5-state model includes cooperative binding of Na(+) ions, strong apparent asymmetry of the energy barriers, a rate-limiting step that is likely associated with the translocation of the empty transporter, and a turnover rate of 21 s(-1). The proposed model is a proof of concept for a novel approach to kinetic modeling of electrogenic transporters and allows insight into the transport mechanism of members of the LeuT structural family at the millisecond timescale. PMID:24944204

  2. 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.

  3. 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 ...

  4. Multiple mechanisms of ligand interaction with the human organic cation transporter, OCT2

    OpenAIRE

    Harper, Jaclyn N.; Wright, Stephen H

    2012-01-01

    OCT2 is the entry step for organic cation (OC) secretion by renal proximal tubules. Although many drugs inhibit OCT2 activity, neither the mechanistic basis of their inhibition nor their transport status is generally known. Using representatives of several structural classes of OCT2-inhibitory ligands described recently (Kido Y, Matsson P, Giacomini KM. J Med Chem 54: 4548–4558, 2011), we determined the kinetic basis of their inhibition of 1-methyl-4-phenylpyridinium (MPP) transport into Chin...

  5. Introduction of Organic Anion Transporters (SLC22A) and a Regulatory Mechanism by Caveolins

    OpenAIRE

    Lee, Woon Kyu; Jung, Sun-Mi; Kwak, Jin-Oh; Cha, Seok Ho

    2006-01-01

    The kidney is an important organ for controlling the volume of body fluids, electrolytic balance and excretion/reabsorption of endogenous and exogenous compounds. Among these renal functions, excretion/reabsorption of endogenous and exogenous substance is very important for the maintenance of physiological homeostasis in the body. Recently discovered organic anion transporters (OAT or SLC22A) have important roles for renal functions. It is well known as drug transporter. Several isoforms belo...

  6. Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols

    OpenAIRE

    Fussen, D.; Vanhellemont, F.; Bingen, C.

    2001-01-01

    Spatio-temporal distributions of stratospheric aerosols, measured by the ORA instrument from August 1992 until May 1993, are presented in the latitude range (40° S–40° N). Particle total number density, mode radius and distribution width are derived and interpreted. The respective roles of advection, sedimentation and coagulation are discussed. We also identify clear transport/sedimentation patterns and we show the enhancement of coagulation in stagnation regions. Efficient transport o...

  7. Differential localization of ion transporters suggests distinct cellular mechanisms for calcification and photosynthesis between two coral species.

    Science.gov (United States)

    Barott, Katie L; Perez, Sidney O; Linsmayer, Lauren B; Tresguerres, Martin

    2015-08-01

    Ion transport is fundamental for multiple physiological processes, including but not limited to pH regulation, calcification, and photosynthesis. Here, we investigated ion-transporting processes in tissues from the corals Acropora yongei and Stylophora pistillata, representatives of the complex and robust clades that diverged over 250 million years ago. Antibodies against complex IV revealed that mitochondria, an essential source of ATP for energetically costly ion transporters, were abundant throughout the tissues of A. yongei. Additionally, transmission electron microscopy revealed septate junctions in all cell layers of A. yongei, as previously reported for S. pistillata, as well as evidence for transcellular vesicular transport in calicoblastic cells. Antibodies against the alpha subunit of Na(+)/K(+)-ATPase (NKA) and plasma membrane Ca(2+)-ATPase (PMCA) immunolabeled cells in the calicoblastic epithelium of both species, suggesting conserved roles in calcification. However, NKA was abundant in the apical membrane of the oral epithelium in A. yongei but not S. pistillata, while PMCA was abundant in the gastroderm of S. pistillata but not A. yongei. These differences indicate that these two coral species utilize distinct pathways to deliver ions to the sites of calcification and photosynthesis. Finally, antibodies against mammalian sodium bicarbonate cotransporters (NBC; SLC4 family) resulted in strong immunostaining in the apical membrane of oral epithelial cells and in calicoblastic cells in A. yongei, a pattern identical to NKA. Characterization of ion transport mechanisms is an essential step toward understanding the cellular mechanisms of coral physiology and will help predict how different coral species respond to environmental stress. PMID:26062631

  8. Transport mechanisms for synoptic, seasonal and interannual SF6 variations and "age" of air in troposphere

    Directory of Open Access Journals (Sweden)

    K. Miyazaki

    2009-02-01

    Full Text Available We use an atmospheric general circulation model (AGCM driven chemistry-transport model (ACTM to simulate the evolution of sulfur hexafluoride (SF6 in the troposphere. The model results are compared with continuous measurements at 6 sites over 71° N–90° S. These comparisons demonstrate that the ACTM simulations lie within the measurement uncertainty over the analysis period (1999–2006 and capture salient features of synoptic, seasonal and interannual SF6 variability. To understand transport timescales of SF6 within the troposphere, transport times of air parcels from the surface to different regions of the troposphere ("age" are estimated from a simulation of an idealized tracer. The age estimation error and its sensitivity to the selection of reanalysis meteorology for ACTM nudging or the tracer transport by deep cumulus convection as represented in the model are discussed. Monthly-mean, 2-box model exchange times (?ex are calculated from both the observed and simulated SF6 time series at the 6 observing sites and show favorable agreement, suggesting that the ACTM adequately represents large-scale interhemispheric transport. The simulated SF6 variability is further investigated through decomposition of the mixing ratio time-tendency into advective, convective, and vertical diffusive components. The transport component analysis illustrates the role of each process in SF6 synoptic variability at the site level and provides insight into the seasonality of ?ex.

  9. A simple modeling approach to elucidate the main transport processes and predict invasive spread: River-mediated invasion of Ageratina adenophora in China

    Science.gov (United States)

    Horvitz, Nir; Wang, Rui; Zhu, Min; Wan, Fang-Hao; Nathan, Ran

    2014-12-01

    A constantly increasing number of alien species invade novel environments and cause enormous damage to both biodiversity and economics worldwide. This global problem is calling for better understanding of the different mechanisms driving invasive spread, hence quantification of a range of dispersal vectors. Yet, methods for elucidating the mechanisms underlying large-scale invasive spread from empirical patterns have not yet been developed. Here we propose a new computationally efficient method to quantify the contribution of different dispersal vectors to the spread rate of invasive plants. Using data collected over 30 years regarding the invasive species Ageratina adenophora since its detection at the Sichuan province, we explored its spread by wind and animals, rivers, and roads into 153 subcounties in the Sichuan, Chongqingshi, and Hubei provinces of China. We found that rivers are the most plausible vector for the rapid invasion of this species in the study area. Model explorations revealed robustness to changes in key assumptions and configuration. Future predictions of this ongoing invasion process project that the species will quickly spread along the Yangtze River and colonize large areas within a few years. Further model developments would provide a much needed tool to mechanistically and realistically describe large-scale invasive spread, providing insights into the underlying mechanisms and an ability to predict future spatial invasive dynamics.

  10. Implementing energy conservation strategies in energy materials transport: U. S. Department of Energy and other government agency policy-making mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Bertram, K. M.

    1978-11-01

    This report defines policy-making channels within Federal agencies for the strategy implementation efforts of a U.S. Department of Energy (DOE) project entitled ''Development and Implementation of Strategies to Conserve Energy in Energy Materials Transport and Through Modal Shifts.'' The report's research involved review and analysis of government-agency policy-making mechanisms. Research methods included interviews with 36 regulatory officials, and review of pertinent legislative, organizational and other technical materials. Emphasis was placed upon relevant Federal agencies and summary treatment given other federal, state, and local agencies. In addition to DOE, the ICC, DOT, DOI, EPA, and Council on Environmental Quality were found to be highly important to the implementation of strategies developed during this project. Brief case studies were also made of states and localities which have had significant effects upon energy materials transport systems. The main findings of the report are that two primary channels exist for effecting this project's policy-oriented strategies: inputs to legislation and inducement of regulatory involvements. In addition, interviews with Federal agency officials during the research produced two significant suggestions for implementing strategies--to hold internal DOE and inter-agency briefings.

  11. 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)

  12. Effect of PANI rate percentage on morphology, structure and charge transport mechanism in PANI–PVDF composites above percolation threshold

    International Nuclear Information System (INIS)

    Polyaniline–Poly(vinylidene) fluoride (PANI–PVDF) composites were prepared by adding PANI to the PVDF by different weight percentages p % (p = 0, 5, 10, 20, … until 100%). The dc and ac electrical conductivity were studied as a function of PANI percentage in the temperature range 303–453 K. The percolation threshold was found to be equal to 2.95%. When the amount of PANI varies from 5 to 30%, the charge transport mechanism was found to be governed by Mott's three-dimensional variable range hopping model and the dc conductivity decreases within this range. For p > 30%, the conductivity increases and the charge transport mechanism are better fitted by a fluctuation induced tunnelling model (FIT). By calculating the distance ‘s’ between two successive clusters (the distance between two active imines centres (=N+H–) of PANI) from the FIT model, we deduce that electron charge transfer is done by inter-chain hopping for the range [p = 40 to 60%] and by intra-chain hopping for p = 70 to 90%. Some insights about the contribution of the ionic charge transport for PANI concentrations in the interval 5% < p < 30% were obtained using impedance measurements at different frequencies. X-ray diffraction measurements, Fourier transform infrared spectroscopy and scanning electron microscopy were used to investigate the effect of PANI on the structure and morphology of composites. (paper)

  13. Baculovirus Infection of Nondividing Mammalian Cells: Mechanisms of Entry and Nuclear Transport of Capsids

    Science.gov (United States)

    van Loo, Nico-Dirk; Fortunati, Elisabetta; Ehlert, Erich; Rabelink, Martijn; Grosveld, Frank; Scholte, Bob J.

    2001-01-01

    We have studied the infection pathway of Autographa californica multinuclear polyhedrosis virus (baculovirus) in mammalian cells. By titration with a baculovirus containing a green fluorescent protein cassette, we found that several, but not all, mammalian cell types can be infected efficiently. In contrast to previous suggestions, our data show that the asialoglycoprotein receptor is not required for efficient infection. We demonstrate for the first time that this baculovirus can infect nondividing mammalian cells, which implies that the baculovirus is able to transport its genome across the nuclear membrane of mammalian cells. Our data further show that the virus enters via endocytosis, followed by an acid-induced fusion event, which releases the nucleocapsid into the cytoplasm. Cytochalasin D strongly reduces the infection efficiency but not the delivery of nucleocapsids to the cytoplasm, suggesting involvement of actin filaments in cytoplasmic transport of the capsids. Electron microscopic analysis shows the cigar-shaped nucleocapsids located at nuclear pores of nondividing cells. Under these conditions, we observed the viral genome, major capsid protein, and electron-dense capsids inside the nucleus. This suggests that the nucleocapsid is transported through the nuclear pore. This mode of transport seems different from viruses with large spherical capsids, such as herpes simplex virus and adenovirus, which are disassembled before nuclear transport of the genome. The implications for the application of baculovirus or its capsid proteins in gene therapy are discussed. PMID:11134309

  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. 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.

  16. Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca2+ release

    DEFF Research Database (Denmark)

    Jensen, Thomas Elbenhardt; Sylow, Lykke

    2014-01-01

    Understanding how muscle contraction orchestrates insulin-independent muscle glucose transport may enable development of hyperglycemia-treating drugs. The prevailing concept implicates Ca(2+) 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 Ca(2+) 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 Ca(2+) centric paradigm.

  17. 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.

  18. 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.

  19. Urban non-motorised transport (NMT): A Critical look at the development of Urban NMT Policy and planning mechanisms in South Africa from 1996 - 2006

    OpenAIRE

    Gwala, Sabelo

    2007-01-01

    Paper presented at the 26th Annual Southern African Transport Conference 9 - 12 July 2007 "The challenges of implementing policy?", CSIR International Convention Centre, Pretoria, South Africa. ABSTRACT:With problems of congestion and pollution in urban areas perhaps greater work is needed in terms of both infrastructure and policy alignment when it comes to urban non-motorised transport (NMT). The objective of reviewing transport planning and policy mechanisms that prevailed during 1996 and ...

  20. Vibrational mechanics in an optical lattice: controlling transport via potential renormalization

    CERN Document Server

    Wickenbrock, A; Wahab, N A Abdul; Phoonthong, P; Cubero, D; Renzoni, F

    2011-01-01

    We demonstrate theoretically and experimentally the phenomenon of vibrational resonance in a periodic potential, using cold atoms in an optical lattice as a model system. A high-frequency (HF) drive, with frequency much larger than any characteristic frequency of the system, is applied by phase-modulating one of the lattice beams. We show that the HF drive leads to the renormalization of the potential. We used transport measurements as a probe of the potential renormalization. The very same experiments also demonstrate that transport can be controlled by the HF drive via potential renormalization.

  1. Pseudorabies Virus Fast Axonal Transport Occurs by a pUS9-Independent Mechanism.

    Science.gov (United States)

    Daniel, Gina R; Sollars, Patricia J; Pickard, Gary E; Smith, Gregory A

    2015-08-01

    Reactivation from latency results in transmission of neurotropic herpesviruses from the nervous system to body surfaces, referred to as anterograde axonal trafficking. The virus-encoded protein pUS9 promotes axonal dissemination by sorting virus particles into axons, but whether it is also an effector of fast axonal transport within axons is unknown. To determine the role of pUS9 in anterograde trafficking, we analyzed the axonal transport of pseudorabies virus in the presence and absence of pUS9. PMID:25995254

  2. 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.

  3. Interaction of PIN and PGP transport mechanisms in auxin distribution-dependent development.

    Czech Academy of Sciences Publication Activity Database

    Mravec, J.; Kubeš, Martin; Bielach, A.; Gaykova, V.; Petrášek, Jan; Sk?pa, Petr; Chand, S.; Benková, E.; Zažímalová, Eva; Friml, J.

    2008-01-01

    Ro?. 135, ?. 20 (2008), s. 3345-3354. ISSN 0950-1991 R&D Projects: GA MŠk(CZ) LC06034; GA AV ?R KJB600380604 Institutional research plan: CEZ:AV0Z50380511 Keywords : PGP * PIN * Auxin transport * Embryogenesis Subject RIV: ED - Physiology Impact factor: 6.812, year: 2008

  4. 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, Ond?ej; Šebera, Jakub; Rosenberg, Ivan; Sychrovský, Vladimír

    2013-01-01

    Ro?. 20, ?. 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

  5. Noble gases as natural tracers of water circulation in the Paris Basin: 1. Measurements and discussion of their origin and mechanisms of vertical transport in the basin

    Science.gov (United States)

    Castro, Maria Clara; Jambon, Albert; de Marsily, Ghislain; Schlosser, Peter

    1998-10-01

    The concentrations and isotopic compositions of helium, neon, and argon were measured in 29 water samples collected from five superposed aquifers in the Paris Basin (Ypresian, Albian, Neocomian, Dogger, and Trias). In all these groundwater flow systems the data showed excesses of 3He, 4He, and 40Ar above the solubility equilibrium with the atmosphere (air saturated water (ASW)), as well as vertical concentration gradients of these isotopes throughout the basin. The water of the Dogger and the Trias formations also had a 21Ne excess above ASW values. The mean rate of radiogenic and nucleogenic isotope production in the entire sedimentary sequence of the basin cannot produce the measured quantities of 3He, 4He, 21Ne, and 40Ar, if reasonable water residence times are considered. The total calculated production is estimated to represent less than about 13% of the measured values for all isotopes. The greater part (>87%) of the radiogenic and nucleogenic noble gas isotopes is thus believed to originate from the bedrock, and the isotopes are transported vertically through the entire basin. Three mechanisms of transport are considered: advection, dispersion, and molecular diffusion. For the Trias the radiogenic/nucleogenic production ratios of 4He/40Ar and 21Ne/40Ar are close to the mean production rate in the crust (4 ± 3 and 0.96 × 10-7, respectively). For the overlying Dogger, however, these ratios are much higher (4He/40Ar: 10 to 70; 21Ne/40Ar: 8 × 10-7 to 23 × 10-7). We suggest that differences in the vertical diffusive flux of 4He, 21Ne, and 40Ar are the reason for the high isotope ratios observed in the Dogger. In the vertical direction, 4He is transported mostly by diffusion, whereas 40Ar is transported mostly by advection. Neon 21 represents an intermediate situation. The distribution of 3He, 4He,21Ne, and 40Ar throughout the basin can be explained by the existence of only two sources: an atmospheric component contributed by recharge water and a radiogenic/nucleogenic component originating mainly in the bedrock. This concept is supported by two-dimensional cross-section modeling of the water flow in the Paris Basin and the advective, dispersive, and diffusive transport of these noble gases in its multiaquifer system presented in part 2 of this study.

  6. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis1. In prokaryotes and photosynthetic eukaryotes, Zn2+-transporting P-type ATPases of class IB (ZntA) are crucial for cellular redistribution and detoxification of Zn2+ and related elements2, 3. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation intermediate (E2·Pi) of ZntA from Shigella sonnei, determined at 3.2 Å and 2.7 Å resolution, respectively. The structures reveal a similar fold to Cu+-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn2+ ions by the transporter. The E2P structure displays a wide extracellular release pathway reaching the invariant residues at the high-affinity site, including C392, C394 and D714. The pathway closes in the E2·Pi state, in which D714 interacts with the conserved residue K693, which possibly stimulates Zn2+ release as a built-in counter ion, as has been proposed for H+-ATPases. Indeed, transport studies in liposomes provide experimental support for ZntA activity without counter transport. These findings suggest a mechanistic link between PIB-type Zn2+-ATPases and PIII-type H+-ATPases and at the same time show structural features of the extracellular release pathway that resemble PII-type ATPases such as the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase4, 5 (SERCA) and Na+, K+-ATPase6. These findings considerably increase our understanding of zinc transport in cells and represent new possibilities for biotechnology and biomedicine.

  7. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis. In prokaryotes and photosynthetic eukaryotes, Zn(2+)-transporting P-type ATPases of class IB (ZntA) are crucial for cellular redistribution and detoxification of Zn(2+) and related elements. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation intermediate (E2·Pi) of ZntA from Shigella sonnei, determined at 3.2 Å and 2.7 Å resolution, respectively. The structures reveal a similar fold to Cu(+)-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn(2+) ions by the transporter. The E2P structure displays a wide extracellular release pathway reaching the invariant residues at the high-affinity site, including C392, C394 and D714. The pathway closes in the E2·Pi state, in which D714 interacts with the conserved residue K693, which possibly stimulates Zn(2+) release as a built-in counter ion, as has been proposed for H(+)-ATPases. Indeed, transport studies in liposomes provide experimental support for ZntA activity without counter transport. These findings suggest a mechanistic link between PIB-type Zn(2+)-ATPases and PIII-type H(+)-ATPases and at the same time show structural features of the extracellular release pathway that resemble PII-type ATPases such as the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA) and Na(+), K(+)-ATPase. These findings considerably increase our understanding of zinc transport in cells and represent new possibilities for biotechnology and biomedicine.

  8. Integrated evaluation of aerogenic pollution by air-transported heavy metals (Pb, Cd, Ni, Zn, Mn and Cu) in the analysis of the main deposit media.

    Science.gov (United States)

    Baltr?nait?, Edita; Baltr?nas, Pranas; Lietuvninkas, Arvydas; Serevi?ien?, Vaida; Zuokait?, Egl?

    2014-01-01

    The composition of the ambient air is constantly changing; therefore, the monitoring of ambient air quality to detect the changes caused by aerogenic pollutants makes the essential part of general environmental monitoring. To achieve more effective improvement of the ambient air quality, the Directive 2008/50/EC on 'Ambient Air Quality and Cleaner Air for Europe' was adopted by the European Parliament and the European Council. It informed the public and enterprises about a negative effect of pollution on humans, animals and plants, as well as about the need for monitoring aerogenic pollutants not only at the continuous monitoring stations but also by using indicator methods, i.e. by analysing natural deposit media. The problem of determining the relationship between the accumulation level of pollutants by a deposit medium and the level of air pollution and its risks is constantly growing in importance. The paper presents a comprehensive analysis of the response of the main four deposit media, i.e. snow cover, soil, pine bark and epigeic mosses, to the long-term pollution by aerogenic pollutants which can be observed in the area of oil refinery influence. Based on the quantitative expressions of the amounts of the accumulated pollutants in the deposit media, the territory of the oil refinery investigated in this paper has been referred to the areas of mild or moderate pollution. PMID:23933956

  9. Aero-Mechanical Design Methodology for Subsonic Civil Transport High-Lift Systems

    Science.gov (United States)

    vanDam, C. P.; Shaw, S. G.; VanderKam, J. C.; Brodeur, R. R.; Rudolph, P. K. C.; Kinney, D.

    2000-01-01

    In today's highly competitive and economically driven commercial aviation market, the trend is to make aircraft systems simpler and to shorten their design cycle which reduces recurring, non-recurring and operating costs. One such system is the high-lift system. A methodology has been developed which merges aerodynamic data with kinematic analysis of the trailing-edge flap mechanism with minimum mechanism definition required. This methodology provides quick and accurate aerodynamic performance prediction for a given flap deployment mechanism early on in the high-lift system preliminary design stage. Sample analysis results for four different deployment mechanisms are presented as well as descriptions of the aerodynamic and mechanism data required for evaluation. Extensions to interactive design capabilities are also discussed.

  10. 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.

  11. 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)

  12. 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)

  13. Determinación de los principales parámetros de calidad que afectan la cosecha mecanizada de arroz / Determination of the main quality parameters that affect the mechanical harvest of rice

    Scientific Electronic Library Online (English)

    Alexander, Miranda Caballero; Ciro E, Iglesias Coronel; Erwin, Herrera González; Nathali, Abraham Ferro; Santiago, Castells Hernández.

    2010-12-01

    Full Text Available El presente trabajo tiene como objetivo analizar la calidad de la cosecha mecanizada de la semilla de arroz, realizada por las cosechadoras de arroz New Holland L521, en las condiciones de trabajo del Complejo Agroindustrial (CAI) Arrocero "Los Palacios". Fueron evaluados los parámetros tecnológicos [...] de la cosechadora en función de la calidad del producto cosechado, tales como: grano entero, pelado y/o quebrado, contenido de impurezas y pérdidas totales. Los resultados obtenidos para los parámetros estudiados indican que para las cosechadoras New Holland L 521 el comportamiento del grano pelado y/o quebrado en los cinco rendimientos agrícolas diferentes observados tomó valores de 5,2-6,4% y el contenido de impurezas estuvo entre 8,3-9,6%, encontrándose ambos parámetros por encima de los límites establecidos, influyendo principalmente en este aspecto la mala regulación de los órganos de trilla, la velocidad trabajo y la mala capacitación de los operadores. La aplicación de estos resultados le permite al CAI Arrocero "Los Palacios" disminuir las pérdidas durante la cosecha se redujeron las pérdidas de 206 kg/ha hasta 85 kg/ha, lo que representa un efecto económico de $ 316 202.04 pesos cubanos y a la vez permite dejar de invertir aproximadamente por la compra del arroz cáscara para ser procesado para la alimentación de nuestra población 184 793.4 USD. Abstract in english The present paper has as objective to analyze quality parameters that affect the mechanical harvest of the seed of rice, carried out by the New Holland L521 rice harvester machine, under the conditions of work of the Rice Enterprise "Los Palacios" the cropper's technological parameters were evaluate [...] d in function of the quality of the harvested product, such as: seed entirely, peeled broken and content of sludges and total losses. The results obtained for the studied parameters indicate that for the New Holland L521 rice harvester machine the behavior of the grain peeled y/o broken in the five observed different agricultural yields took values of 5,2-6,4% and the content of sludges was among 8,3-9,6%, being both parameters above the established limits, influencing mainly in this aspect the bad regulation of the organs of it thrashes, the speed work and the bad training of the operators. The application of these results allows him to the Rice Enterprise "Los Palacios to diminish the losses during the crop decreased the losses of 206 kg/ha up to 85 kg/ha, what represents an economic effect of $316 202.04 Cuban pesos and at the same time allows to stop to invest approximately for the purchase of the rice shell to be processed for our population's feeding 184 793.4 USD.

  14. Main regularities in variations of mechanical properties and microstructure of fuel element assembly can material (steel EhP-450) irradiated in BN-600 and BN-350 reactors

    International Nuclear Information System (INIS)

    The complex of mechanical properties of steel EhP-450 fuel assembly cans irradiated in fast reactors was under study. The steel is shown to possess a high resistance to swelling as well as acceptable values of mechanical properties under tension and impact bending. Based on the results obtained a conclusion is made that in a low-temperature zone of BN-600 reactor fuel assembly cans at 15% burnup the most essential change in mechanical properties should be expected in the vicinity of a lower reactor core boundary at damaging doses of 20-40 dpa

  15. A quantum mechanical flux correlation approach to steady-state transport rates in molecular junctions

    Energy Technology Data Exchange (ETDEWEB)

    Caspary Toroker, Maytal [Schulich Faculty of Chemistry, Lise Meitner Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Peskin, Uri, E-mail: uri@tx.technion.ac.il [Schulich Faculty of Chemistry, Lise Meitner Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2010-05-12

    A time-dependent approach for the calculation of steady-state currents through molecular junctions is presented. Using the close analogy between electronic currents and thermal reactive scattering rates, algorithms and methodologies originally developed for calculations of thermal reaction rates are utilized for electronic transport calculations. Resonant transport is considered in detail, in view of the dominant contribution of resonance states to the current in molecular junctions. The problem of long-time delays due to population of long-lived resonances is a challenge for most time-dependent calculation of steady-state currents, involving an infinite time-limit. A solution to this problem is presented by reformulating a flux-averaging method for the molecular junction scenario. The new formulation is implemented for commonly used simple tight binding models of molecular junctions, demonstrating its numerical advantages.

  16. A quantum mechanical flux correlation approach to steady-state transport rates in molecular junctions

    International Nuclear Information System (INIS)

    A time-dependent approach for the calculation of steady-state currents through molecular junctions is presented. Using the close analogy between electronic currents and thermal reactive scattering rates, algorithms and methodologies originally developed for calculations of thermal reaction rates are utilized for electronic transport calculations. Resonant transport is considered in detail, in view of the dominant contribution of resonance states to the current in molecular junctions. The problem of long-time delays due to population of long-lived resonances is a challenge for most time-dependent calculation of steady-state currents, involving an infinite time-limit. A solution to this problem is presented by reformulating a flux-averaging method for the molecular junction scenario. The new formulation is implemented for commonly used simple tight binding models of molecular junctions, demonstrating its numerical advantages.

  17. Investigation of silicate surface chemistry and reaction mechanisms associated with mass transport in geologic media

    International Nuclear Information System (INIS)

    The concentration and rate of transport of radionuclides through geologic media can be strongly influenced by the extent of sorption on aquifer surfaces. Over time intervals relevant to such transport processes, rock and mineral surfaces cannot be considered as inert, unreactive substrates but rather as groundwater/solidphase interfaces which are commonly in a state of natural or artificially induced disequilibrium. The goal of the present research is to define experimentally the type of water/rock interactions that will influence surface chemistry and hence sorption characteristics and capacities of natural aquifers. As wide a range of silicate minerals as possible was selected for study to represent rock-forming minerals in basalt, tuff, and granite. The minerals include K-feldspar, plagioclase feldspar, olivine, hornblende, biotite, and volcanic glass

  18. Mechanism of Insulin-resistant Glucose Transport Activity in the Enlarged Adipose Cell of the Aged, Obese Rat: RELATIVE DEPLETION OF INTRACELLULAR GLUCOSE TRANSPORT SYSTEMS

    OpenAIRE

    Hissin, Paul J.; Foley, James E; Wardzala, Lawrence J.; Karnieli, Eddy; Simpson, Ian A.; Salans, Lester B.; Cushman, Samuel W.

    1982-01-01

    The effects of increasing cell size on glucose transport activity and metabolism and on the concentrations of glucose transport systems in both the plasma and low density microsomal membranes in isolated adipose cells from the aging rat model of obesity have been examined. Glucose transport activity was assessed by measuring l-arabinose transport and the concentration of glucose transport systems estimated by measuring specific d-glucose-inhibitable cytochalasin B-binding. Basal glucose trans...

  19. Charge carrier transport mechanisms in perovskite CdTiO3 fibers

    OpenAIRE

    Z. Imran; M. A. Rafiq; Hasan, M. M.

    2014-01-01

    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 d...

  20. Transport Mechanism in Polyethylene Membrane during Vapor Permeation of Propan-1-ol and Toluene.

    Czech Academy of Sciences Publication Activity Database

    Fialová, Kate?ina; Petri?kovi?, Roman; Uchytil, Petr

    Sofia : University of Chemical Technology and Metallurgy, 2005 - (Mehmetli, E.; Kemperman, A.; Kozhukharov, V.), s. 45-50 ISBN 954-8954-55-9. [Application of Nanotechnologies for Separation and Recovery of Volatile Organic Compounds from Waste Air Streams. Istanbul (TR), 30.05.2005-01.06.2005] R&D Projects: GA AV ?R(CZ) IAA4072402 Institutional research plan: CEZ:AV0Z40720504 Keywords : vapor permeation * sorption * transport model Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  1. Towards the Restructuring and Co-ordination Mechanisms for the Architecture of Chinese Transport Logistics

    OpenAIRE

    Yang, J.

    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 transpo...

  2. Synthesis, transport and mechanism of a type I prodrug: L-carnitine ester of prednisolone.

    Science.gov (United States)

    Mo, Jing-xin; Shi, San-jun; Zhang, Qin; Gong, Tao; Sun, Xun; Zhang, Zhi-rong

    2011-10-01

    Aerosol glucocorticoid medications have become more and more important in treating BA (bronchial asthma). Although these agents are dosed to directly target airway inflammation, adrenocortical suppression and other systematic effects are still seen. To tackle this problem in a novel way, two L-carnitine ester derivatives of prednisolone (as the model drug), namely, PDC and PDSC, were synthesized to increase the absorption of prednisolone across the human bronchial epithelial BEAS-2B cells by the organic cation/carnitine transporter OCTN2 (SLC22A5) and then to slowly and intracellularly release prednisolone. The transport of prednisolone, PDC and PDSC into the human bronchial epithelial BEAS-2B cells was in the order PDSC > prednisolone > PDC at 37 °C. It was found that PDSC displayed 1.79-fold increase of uptake compared to prednisolone. Transport of PDSC by BEAS-2B was temperature-, time-, and Na(+)-dependent and saturable, with an apparent K(m) value of 329.74 ?M, suggesting the involvement of carrier-mediated uptake. An RT-PCR study showed that organic cation/carnitine transporters OCTN1 and OCTN2 are expressed in BEAS-2B cells, but little in HEK293T cells. The order of uptake by HEK293T was prednisolone > PDC > PDSC. In addition, the inhibitory effects of organic cations such as L-carnitine, ergothioneine, TEA(+) and ipratropium on PDSC uptake in BEAS-2B cells were in the order L-carnitine > ipratropium > TEA(+) > ergothioneine, whereas their inhibitory effects on PDSC uptake in HEK293T cells were negligible. Finally, in vitro LPS-induced IL-6 production from BEAS-2B was more and longer suppressed by PDSC than prednisolone and PDC. All of these results suggested PDSC may be an attractive candidate for asthma treatment. PMID:21854030

  3. MAJOR TRANSPORT MECHANISMS OF PYRETHROIDS IN RESIDENTIAL SETTINGS AND EFFECTS OF MITIGATION MEASURES

    OpenAIRE

    Davidson, Paul C; Jones, Russell L.; Harbourt, Christopher M; Hendley, Paul; Goodwin, Gregory E; Sliz, Bradley A

    2013-01-01

    The major pathways for transport of pyrethroids were determined in runoff studies conducted at a full-scale test facility in central California, USA. The 6 replicate house lots were typical of front lawns and house fronts of California residential developments and consisted of stucco walls, garage doors, driveways, and residential lawn irrigation sprinkler systems. Each of the 6 lots also included a rainfall simulator to generate artificial rainfall events. Different pyrethroids were applied ...

  4. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg; Meloni, Gabriele; Autzen, Henriette Elisabeth; Andersson, Magnus; Klymchuk, Tetyana; Nielsen, Anna Marie; Rees, Douglas C; Nissen, Poul; Gourdon, Pontus

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis1. In prokaryotes and photosynthetic eukaryotes, Zn2+-transporting P-type ATPases of class IB (ZntA) are crucial for cellular redistribution and detoxification of Zn2+ and related elements2, 3. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation...

  5. Receptor-mediated transcytosis: a mechanism for active extravascular transport of nanoparticles in solid tumors

    OpenAIRE

    Lu, Wei; Xiong, Chiyi; Zhang, Rui; Shi, Lifang; Huang, Miao; Zhang, Guodong; Song, Shaoli; Huang, Qian; Liu, Gang-Yu; Li, Chun

    2012-01-01

    Targeted nanoparticle-based delivery systems have been used extensively to develop effective cancer theranostics. However, how targeting ligands affect extravascular transport of nanoparticles in solid tumors remains unclear. Here, we show, using B16/F10 melanoma cells expressing melanocortin type-1 receptor (MC1R), that the nature of targeting ligands, i.e., whether they are agonists or antagonists, directs tumor uptake and intratumoral distribution after extravasation of nanoparticles from ...

  6. Description of Transport Mechanism in Polymeric Membrane via Sorption in Steady State.

    Czech Academy of Sciences Publication Activity Database

    Fialová, Kate?ina

    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 ?R GD203/03/H140; GA AV ?R IAA4072402 Institutional research plan: CEZ:AV0Z4072921 Keywords : vapor permeation * pervaporation * membrane transport Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  7. 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 ?-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 ?-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)

  8. Ab initio study of the stabilities of and mechanism of superionic transport in lithium-rich antiperovskites

    Science.gov (United States)

    Zhang, Yi; Zhao, Yusheng; Chen, Changfeng

    2013-04-01

    Recently, a family of halogen-based Li-rich antiperovskites were synthesized [J. Am. Chem. Soc.JACSAT0002-786310.1021/ja305709z 134, 15042 (2012)], and the measured superionic conductivity makes these materials promising candidates as solid electrolytes for applications in Li-ion and Li-air batteries. This discovery raises several pressing issues on the fundamental physics concerning the thermodynamic and electrochemical stability of the synthesized materials and the mechanism of the observed superionic Li+ transport. Here, we study the reported antiperovskites Li3OCl, Li3OBr, and their mixed compounds using first-principles density functional theory and molecular dynamics simulations. Our calculations show that these materials are thermodynamically metastable. Their large electronic band gaps and chemical stability against electrodes suggest the excellent electrochemical performance, which bodes well for the use in potentially harsh working conditions in practical battery applications. The calculated low activation enthalpy for Li-ion migration well below the crystal melting temperature and superionic transport near the Li sublattice melting state explain the experimentally observed phenomena. Our study identifies mobile Li vacancies and anion disorder as the primary driving mechanisms for superionic Li+ conductivity in the antiperovskites. This work unveils essential working principles of the Li-rich antiperovskites, which are crucial to further exploration, development, and application of these and other charge-inverted materials with tailored properties.

  9. Down-regulation of mechanisms involved in cell transport and maintenance of mucosal integrity in pigs infected with Lawsonia intracellularis.

    Science.gov (United States)

    Smith, Sionagh H; Wilson, Alison D; Van Ettinger, Imke; MacIntyre, Neil; Archibald, Alan L; Ait-Ali, Tahar

    2014-01-01

    Lawsonia intracellularis is an obligate intracellular bacterium, responsible for the disease complex known as proliferative enteropathy (PE). L. intracellularis is associated with intestinal crypt epithelial cell proliferation but the mechanisms responsible are yet to be defined. Microarray analysis was used to investigate the host-pathogen interaction in experimentally infected pigs to identify pathways that may be involved. Ileal samples originating from twenty-eight weaner pigs experimentally challenged with a pure culture of L. intracellularis (strain LR189/5/83) were subjected to microarray analysis. Microarray transcriptional signatures were validated using immunohistochemistry and quantitative real time PCR of selected genes at various time points post challenge. At peak of infection (14 days post challenge) 86% of altered transcripts were down regulated, particularly those involved in maintenance of mucosal integrity and regulation of cell transport. Among the up-regulated transcripts, CD163 and CDK1 were novel findings and considered to be important, due to their respective roles in innate immunity and cellular proliferation. Overall, targeted cellular mechanisms included those that are important in epithelial restitution, migration and protection; maintenance of stable inter-epithelial cell relationships; cell transport of nutrients and electrolytes; innate immunity; and cell cycle. PMID:24885874

  10. 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. PMID:26076303

  11. FSV technology for passenger, materials and coarse debris transport in the main roadway network of the Haard satellite mine. Final report; Gleislostechnik fuer Personenbefoerderung, Material- und Grobbergetransport im Hauptstreckennetz des Anschlussbergwerkes Haard. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Einhaeuser, J.

    1992-09-01

    A free-steered transport system was developed which can be used for passenger, materials and, with restrictions, debris transport around the shaft (distance max. 4 km). The system includes all-wheel driven or center pivot steered passenger busses with max. 26 seats, a combination of trucks with trailers (20 t payload) and material transporters (5 and 8 t) as well as special vehicles for heavy loads of up to 14 t (shield supports) and loaders (4 and 6 t) for dinting, loading and transport work. The vehicles can be used in roadways with free cross sections of more than 3 m width and 2.4 m height and inclinations of up to 1 in 4. For inclinations of more than 1 in 10 the transport velocity is insufficient (with the exception of the loaders) because suitable Diesel engines are currently not available for the vehicles. The applicability of the vehicles is mainly determined by the condition of the lanes or roadways. Suitable lane construction methods were developed. An EDP assisted transport simulation model is available for the planning work. (orig.) [Deutsch] Es wurde ein gleisloses Transportsystem entwickelt, das fuer den schachtnahen Bereich (Umkreis max. 4 km) fuer die Personenbefoerderung, den Materialtransport und mit Einschraenkungen fuer den Bergetransport (Haufwerkstransport) einsetzbar ist. Das System besteht aus allrad- oder knickgelenkten Personenbussen bis maximal 26 Sitzplaetze, aus einer Kombination von Sattelschleppern mit Anhaengern (Nutzlast 20 t) und Materialtransportern (5 und 8 t) sowie Sonderfahrzeugen fuer Schwerlasten bis 14 t (Schildausbau und aus Fahrladern (4 und 6 t) fuer Senk-, Lade- und Transportarbeiten. Die Fahrzeuge sind einsetzbar in Strecken mit Lichtraumprofil ueber 3 m Breite und 2,4 m Hoehe, sowie Steigungen bis 15 Gon = 25%. Bei Neigungen ueber 6 Gon = 10% ist (bis auf die Fahrlader) die Transportgeschwindigkeit unzureichend, weil fuer die Fahrzeuge zur Zeit keine geeigneten Dieselmotoren gebaut werden. Die Betriebsbereitschaft der Fahrzeuge wird massgeblich durch den Zustand der Fahrbahnen bzw. der Strecken bestimmt. Geeignete Verfahren zum Fahrbahnbau wurden entwickelt. Fuer die Planung steht ein EDV-gestuetztes Transportmodel zur Verfuegung. (orig.)

  12. The Mechanism of Phloem Loading in Rice (Oryza sativa)

    OpenAIRE

    Eom, Joon-Seob; Choi, Sang-Bong; Ward, John M.; Jeon, Jong-Seong

    2012-01-01

    Carbohydrates, mainly sucrose, that are synthesized in source organs are transported to sink organs to support growth and development. Phloem loading of sucrose is a crucial step that drives long-distance transport by elevating hydrostatic pressure in the phloem. Three phloem loading strategies have been identified, two active mechanisms, apoplastic loading via sucrose transporters and symplastic polymer trapping, and one passive mechanism. The first two active loading mechanisms require meta...

  13. 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)

  14. 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.)

  15. Electronic transport mechanisms in scaled gate-all-around silicon nanowire transistor arrays

    International Nuclear Information System (INIS)

    Low-frequency noise is used to study the electronic transport in arrays of 14?nm gate length vertical silicon nanowire devices. We demonstrate that, even at such scaling, the electrostatic control of the gate-all-around is sufficient in the sub-threshold voltage region to confine charges in the heart of the wire, and the extremely low noise level is comparable to that of high quality epitaxial layers. Although contact noise can already be a source of poor transistor operation above threshold voltage for few nanowires, nanowire parallelization drastically reduces its impact

  16. 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.)

  17. Ubiquitination as a Mechanism To Transport Soluble Mycobacterial and Eukaryotic Proteins to Exosomes.

    Science.gov (United States)

    Smith, Victoria L; Jackson, Liam; Schorey, Jeffrey S

    2015-09-15

    Exosomes are extracellular vesicles of endocytic origin that function in intercellular communication. Our previous studies indicate that exosomes released from Mycobacterium tuberculosis-infected macrophages contain soluble mycobacterial proteins. However, it was unclear how these secreted proteins were targeted to exosomes. In this study, we determined that exosome production by the murine macrophage cell line RAW264.7 requires the endosomal sorting complexes required for transport and that trafficking of mycobacterial proteins from phagocytosed bacilli to exosomes was dependent on protein ubiquitination. Moreover, soluble mycobacterial proteins, when added exogenously to RAW264.7 or human HEK293 cells, were endocytosed, ubiquitinated, and released via exosomes. This suggested that endocytosed proteins could be recycled from cells through exosomes. This hypothesis was supported using the tumor-associated protein He4, which, when endocytosed by RAW264.7 or HEK293 cells, was transported to exosomes in a ubiquitin-dependent manner. Our data suggest that ubiquitination is a modification sufficient for trafficking soluble proteins within the phagocytic/endocytic network to exosomes. PMID:26246139

  18. Protein Electronic Conductors: Hemin-Substrate Bonding Dictates Transport Mechanism and Efficiency across Myoglobin.

    Science.gov (United States)

    Raichlin, Sara; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2015-10-12

    Electron transport (ETp) across met-myoglobin (m-Mb), as measured in a solid-state-like configuration between two electronic contacts, increases by up to 20 fold if Mb is covalently bound to one of the contacts, a Si electrode, in an oriented manner by its hemin (ferric) group, rather than in a non-oriented manner. Oriented binding of Mb is achieved by covalently binding hemin molecules to form a monolayer on the Si electrode, followed by reconstitution with apo-Mb. We found that the ETp temperature dependence (>120?K) of non-oriented m-Mb virtually disappears when bound in an oriented manner by the hemin group. Our results highlight that combining direct chemical coupling of the protein to one of the electrodes with uniform protein orientation strongly improves the efficiency of ET across the protein. We hypothesize that the behavior of reconstituted m-Mb is due to both strong protein-substrate electronic coupling (which is likely greater than in non-oriented m-Mb) and direct access to a highly efficient transport path provided by the hemin group in this configuration. PMID:26346916

  19. Theoretical preconditions and technical substantiation for mechanical compressed air drying method application on the railway transport

    Directory of Open Access Journals (Sweden)

    Tatiana RIPOL’-SARAGOSI

    2009-01-01

    Full Text Available The article is related to the compressed air purification for the rolling stock problems. The mechanical method is described as a potential way of the compressed air cooling and purificating. The temperature field at the heat conducting surface engineer function equation is given in the article as well.

  20. 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

  1. A Mechanism for a Tropical Cloud Thermostat in response to Ocean Heat Transport Changes

    Science.gov (United States)

    Koll, D.; Pierrehumbert, R.; Abbot, D. S.

    2011-12-01

    Past studies have proposed that clouds could hold tropical temperatures constant in response to rising CO2 levels and thus act like a tropical thermostat. If such a thermostat exists, it would help explain the low meridional temperature gradients during the Pliocene and Eocene. Subsequent observational and theoretical work, however, has raised questions about the validity of a tropical cloud thermostat in response to changes in CO2 . Independently, recent work has suggested that tropical cyclones could have increased the ocean heat transport (OHT) and lowered temperature gradients in the Pliocene and Eocene. This motivates further theoretical investigation of the influence of OHT on tropical and global mean temperature. We consider this question with a global climate model (CAM4 and CAM5) that is coupled to a slab ocean run in aquaplanet mode with no sea ice. We force the model with an idealized OHT profile and vary the amplitude of the profile. We find that increased OHT raises global mean temperature and decreases the temperature gradient, consistent with previous studies. Unlike other studies, we also find a negative tropical cloud feedback that keeps tropical temperatures nearly constant in response to OHT changes, i.e., a cloud thermostat. The thermostat is linked to the global water feedback and atmospheric circulation. Increasing the OHT causes less evaporation in the tropics and a weaker Hadley circulation, both of which dry the deep tropics. This leads to less reflective clouds in the deep tropics, which causes a warming and counteracts the cooling effects of increased ocean heat export from the tropics. We investigate the thermostat's robustness across a large range of ocean heat transport strengths, including cases in which the ocean reverses its transport. We find that global temperatures and tropical clouds respond approximately linearly and antisymetrically to changes in OHT (see figure). In contrast, increases in CO2 cause a simple warming of both the equatorial and global mean temperature (see figure). Our results are dependent on the CAM cloud schemes, although the cloud response is driven by atmospheric circulation changes that are robust in multiple other models. If confirmed, this thermostat could help explain the relative stability of tropical temperatures in warm past climates.

  2. Mechanisms of hepatic transport of cyclosporin A: an explanation for its cholestatic action?

    Science.gov (United States)

    Fricker, G; Fahr, A

    1997-01-01

    The hepatic transport of the immunosuppressive Cyclosporin A (CyA) was studied using liposomal phospholipid membranes, freshly isolated rat hepatocytes and bile canalicular plasma membrane vesicles from rat liver. The Na(+)-dependent, saturable uptake of the bile acid 3H-taurocholate into isolated rat liver cells was apparently competitively inhibited by CyA. However, the uptake of CyA into the cells was neither saturable, nor temperature-dependent nor Na(+)-dependent, nor could it be inhibited by bile salts or CyA-derivatives, indicating passive diffusion. In steady state depolarization fluorescence studies, CyA caused a concentration-dependent decrease of anisotropy, indicating a membrane fluidizing effect. Ion flux experiments demonstrated that CyA dramatically increases the permeability of Na+ and Ca2+ across phospholipid membranes in a dose- and time-dependent manner, suggesting a iontophoretic activity that might have a direct impact on cellular ion homeostasis and regulation of bile acid uptake. Photoaffinity labeling with a [3H]-labeled photolabile CyA-derivative resulted in the predominant incorporation of radioactivity into a membrane polypeptide with an apparent molecular weight of 160,000 and a minor labeling of polypeptides with molecular weights of 85,000-90,000. In contrast, use of a photolabile bile acid resulted in the labeling of a membrane polypeptide with an apparent molecular weight of 110,000, representing the bile canalicular bile acid carrier. The photoaffinity labeling as well as CyA transport by canalicular membrane vesicles were inhibited by CyA and the p-glycoprotein substrates daunomycin and PSC-833, but not by taurocholate, indicating that CyA is excreted by p-glycoprotein. CyA uptake by bile canalicular membrane vesicles was ATP-dependent and could not be inhibited by taurocholate. CyA caused a decrease in the maximum amount of bile salt accumulated by the vesicles with time. However, initial rates of [3H]-taurocholate uptake within the first 2.5 min remained unchanged at increasing CyA concentrations. In summary, the data indicate that CyA does not directly interact with the hepatic bile acid transport systems. Its cholestatic action may rather be the result of alterations in membrane fluidity, intracellular effects and an interaction with p-glycoprotein. PMID:9626758

  3. 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.

  4. Fractional quantum mechanics on networks: Long-range dynamics and quantum transport

    Science.gov (United States)

    Riascos, A. P.; Mateos, José L.

    2015-11-01

    In this paper we study the quantum transport on networks with a temporal evolution governed by the fractional Schrödinger equation. We generalize the dynamics based on continuous-time quantum walks, with transitions to nearest neighbors on the network, to the fractional case that allows long-range displacements. By using the fractional Laplacian matrix of a network, we establish a formalism that combines a long-range dynamics with the quantum superposition of states; this general approach applies to any type of connected undirected networks, including regular, random, and complex networks, and can be implemented from the spectral properties of the Laplacian matrix. We study the fractional dynamics and its capacity to explore the network by means of the transition probability, the average probability of return, and global quantities that characterize the efficiency of this quantum process. As a particular case, we explore analytically these quantities for circulant networks such as rings, interacting cycles, and complete graphs.

  5. Numerical simulation of dynamic deformation of a spent nuclear fuel transport package in accidental mechanical impacts

    International Nuclear Information System (INIS)

    Numerical simulation results and their analysis are presented for dynamic deformations of the TUK-117 package, intended for the transport of spent nuclear fuel from nuclear power plants, subjected to accidental 9 m drops on to an unyielding surface at different angles. This paper focuses on the analysis of the deformation behaviour of container shock limiters. It is demonstrated that maximum loading affects the package during a side drop. For a side drop, the maximum strain levels are determined for the different construction elements, including the cask's body and the bolts securing the sealing lid. Dynamic simulation of the behaviour of the construction elements was carried out using the LS-DYNA code, version 970. (author)

  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. 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 ?mol/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.

  8. Thermodynamic, transport and mechanical properties of amorphous metallic alloys: Relation to the glass transition

    International Nuclear Information System (INIS)

    Properties related to the glass transition of metallic melts are reviewed both on empirical ground and using the statistics of local minima in the potential energy landscape of the material. For metallic alloys some correlations have been disputed (e.g., the one between the Kauzmann and VFT temperatures). In the first part of this report these issues are considered and the possible reasons for either good or poor correlation are outlined. Then the relationship of the glass transition to mechanical properties (e.g., strength, moduli) is described with special attention to the failure mechanism of amorphous alloys via shear band propagation. The relationships are discussed for glass-forming alloys in comparison also with properties of other families of glass-formers.

  9. A hopping mechanism for cargo transport by molecular motors in crowded microtubules

    OpenAIRE

    Goldman, Carla

    2010-01-01

    Most models designed to study the bidirectional movement of cargos as they are driven by molecular motors rely on the idea that motors of different polarities can be coordinated by external agents if arranged into a motor-cargo complex to perform the necessary work [gross04]. Although these models have provided us with important insights into these phenomena, there are still many unanswered questions regarding the mechanisms through which the movement of the complex takes pl...

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

    OpenAIRE

    Iliev, Bozhidar Z.

    1998-01-01

    We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one but it is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it a pure state of some quantum system is described by a state section (along paths) of a (Hilbert) fibre bundle. Its evolution is determined through the bundle (analogue of the) Schr\\"odinger...

  11. Fibre bundle formulation of nonrelativistic quantum mechanics. IV. Mixed states and evolution transport's curvature

    OpenAIRE

    Iliev, Bozhidar Z.

    1999-01-01

    We propose a new systematic fibre bundle formulation of nonrelativistic quantum mechanics. The new form of the theory is equivalent to the usual one but it is in harmony with the modern trends in theoretical physics and potentially admits new generalizations in different directions. In it a pure state of some quantum system is described by a state section (along paths) of a (Hilbert) fibre bundle. It's evolution is determined through the bundle (analogue of the) Schr\\"odinge...

  12. The influence of Morphology on the Transport and Mechanical Properties of Polyethylene

    OpenAIRE

    Neway, Bereket

    2003-01-01

    The sorption/desorption behaviour of n-hexane in high molarmass linear polyethylene (PE) and branched PEs with 0.39 and5.09 hexyl branches per 100 main chain C atoms andcrystallinities between 4 and 82% at 298 K has been studied.Crystal core contents determined by Raman spectroscopy werealways lower than those determined by density measurements. Then-hexane solubilities in the copolymers depended in anon-linear manner on the content of penetrable polymercomponent and were lower for homogeneou...

  13. Crustal melt granites and migmatites along the Himalaya: melt source, segregation, transport and granite emplacement mechanisms

    OpenAIRE

    Searle, MP; Cottle, JM; Streule, MJ; Waters, DJ

    2010-01-01

    India-Asia collision resulted in crustal thickening and shortening, metamorphism and partial melting along the 2200 km-long Himalayan range. In the core of the Greater Himalaya, widespread in situ partial melting in sillimanite+K-feldspar gneisses resulted in formation of migmatites and Ms+Bt+Grt+Tur±Crd±Sil leucogranites, mainly by muscovite dehydration melting. Melting occurred at shallow depths (4-6 kbar; 15-20 km depth) in the middle crust, but not in the lower crust. 87Sr/ 86Sr ratios of...

  14. Environmental Impact of Flooding in the Main (Smallwood) Reservoir of the Churchill Falls Power Plant, Labrador, Canada. II. Chemical and Mechanical Analysis of Flooded Trees and Shoreline Changes.

    OpenAIRE

    Bruce A. Roberts; Denes Bajzak

    2011-01-01

    The Churchill Falls Hydro Project (called the “Upper Churchill Development”) in Labrador, Canada, was initiated in the late 1960s. At that time, in general, not much attention was paid to the impact of such devel-opment on the flooding of vegetation especially forest stands. Both forested and un-forested terrestrial vege-tation types were flooded (244 915 ha). Some islands were created and in addition portions of existing areas were flooded to form islands (74 075 ha) in the Main (Smallwood) ...

  15. 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.

  16. 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.

  17. Modeling Breadcrust Bombs to Better Understand Their Transportation Mechanisms and Thermal History

    Science.gov (United States)

    Benage, M. C.; Dufek, J.; Degruyter, W.

    2012-12-01

    The thermal history of pyroclastic density currents (PDCs) can influence their runout distance and dynamics and provides information about the concentration field and air entrainment in these flows. We have been investigating breadcrust bombs contained in PDCs as useful thermal proxies that can also be contrasted with ballistically ejected breadcrust bombs. Breadcrust bombs can have dense, non-vesicular rinds and/or surface cracks and are usually basaltic to andesitic in composition. Their textures may contain clues to the way they were transported, the thermal history they underwent, and their initial water concentration. To better interpret these textures, we model the morphology of the bomb as it is being transported. The juvenile clasts are modeled as Lagrangian particles in a coupled multiphase numerical model (Eulerian-Eulerian-Lagrangian [EEL]) that tracks the heat exchange between the current and the clasts. The volcanic clast morphology is modeled by coupling cooling, viscosity, and bubble growth models and the glass transition temperature. The cooling of the clast is calculated by convective and radiative heat transfer to the surrounding environment, as well as conductive cooling. The temperature profile of the clast is then used, along with composition of the clast, to calculate the distribution of viscosity. Viscosity can have a significant impact on restricting bubble growth within the clast. The Proussevitch et al., (1993) numerical bubble growth model is included to calculate post-eruption bubble evolution and the clast morphology, such as rind thickness and bubble size distributions. We examined the likely morphology of clasts that develop in PDCs and ballistic trajectories. We ran multiple models of ballistic and PDC eruptions with varying conditions such as initial current temperature, initial clast temperature, and initial water concentration. The results show that ballistic clasts rapidly cool and produce thicker rinds for higher temperature eruptions. There is less of a difference between the rind of a ballistic and PDC clast if the erupting gas temperature is low. However, the bubble sizes and rinds are also a function of the clast's initial water concentration. Therefore, the modeled volcanic clast's morphology is dependent not only on the cooling regime and rate but also the initial water content in the erupting magmatic clasts. We conclude that breadcrust bombs can provide information about the initial eruption temperature, water concentration, and that they are good proxies for the thermal history of a current, which is critical in determining current dynamics and deposit characteristics.

  18. Investigation of transport mechanisms in Bi doped Ge2Sb2Te5 thin films for phase change memory application

    Science.gov (United States)

    Lazarenko, Petr I.; Sherchenkov, Alexey A.; Kozyukhin, Sergey S.; Shtern, Maxim Y.; Timoshenkov, Sergey P.; Gromov, Dmitry G.; Redichev, Evgeniy N.

    2014-12-01

    The influence of Bi doping on the charge carrier transport mechanism in GST225 thin films was investigated. The three regions with different current-voltage dependencies were established. The energy diagrams for Bi doped GST225 thin films for different regions were analyzed. Analysis of experimental data showed that space charge limited current is the most possible explanation for the nonlinear I-V dependence in the middle electrical field strength (103 mobility gap, Urbach energy, density distribution of localized states, and activation energy of conductivity. The most pronounced modification of current-voltage characteristic and parameters of the thin films was established for GST225 + 0,5 wt. % Bi. Thus, doping of Ge2Sb2Te5 by Bi expands the range of material properties, which is important for the optimization of PCM technology.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.)

  5. Molecular mechanism of pH-dependent substrate transport by an arginine-agmatine antiporter

    OpenAIRE

    Wang, Sheng; Yan, Renhong; Zhang, Xi; Chu, Qi; Shi, Yigong

    2014-01-01

    Enteropathogenic bacteria, exemplified by Escherichia coli strain O157:H7, rely on elaborate acid-resistance systems (ARs) to survive the extremely acidic environment of the stomach. The amino acid antiporter AdiC plays a key role in AR3 and is activated only under acidic pH conditions. Despite elucidation of crystal structures, the molecular mechanism by which AdiC senses acidic pH remains unknown. In this study, we have identified a single aromatic amino acid, Tyr74, as a pH sensor in AdiC....

  6. Upregulation of the Rab27a-Dependent Trafficking and Secretory Mechanisms Improves Lysosomal Transport, Alleviates Endoplasmic Reticulum Stress, and Reduces Lysosome Overload in Cystinosis

    OpenAIRE

    Johnson, Jennifer L; Napolitano, Gennaro; Monfregola, Jlenia; Rocca, Celine J; Cherqui, Stephanie; Catz, Sergio D

    2013-01-01

    Cystinosis is a lysosomal storage disorder caused by the accumulation of the amino acid cystine due to genetic defects in the CTNS gene, which encodes cystinosin, the lysosomal cystine transporter. Although many cellular dysfunctions have been described in cystinosis, the mechanisms leading to these defects are not well understood. Here, we show that increased lysosomal overload induced by accumulated cystine leads to cellular abnormalities, including vesicular transport defects and increased...

  7. 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.

  8. Determination of micro-mechanical parameters of primary heat transport piping material of Pressurised Heavy Water Reactor

    International Nuclear Information System (INIS)

    Models being developed for numerical simulation of ductile fracture require a number of input parameters, which are known as micro-mechanical parameters. The micro-mechanical parameters of the primary heat transport (PHT) piping material of pressurised heavy water reactor (PHWR) are not known. A study has been carried out to understand the micro-void development and to determine the three important micro-mechanical parameters of this material namely, initial void volume fraction (fo), critical void volume fraction (fc) and void volume fraction at final failure (fF). Initial void volume fraction (fo) was determined by measuring inclusion volume fraction by quantitative image analysis of photomicrographs taken on the as polished surface of the samples cut of PHT piping piece. Micro-void development in the material was studied using scanning electron microscope (SEM) on specimens sectioned from the tensile tested specimens. For this purpose, nine smooth round bar tensile testing specimens were subjected to uniaxial tension test. Six samples underwent interrupted test while three were loaded till fracture occurred. The critical void volume fraction (fc) and the void volume fraction at fracture (fF) were estimated from the fracture surfaces of the tensile specimens. The study of sections from the interrupted tests showed that voids were present in the material around inclusions when the diameter reduction during tension test was 10.5% or more. However, no micro-voids were seen in the specimens in which the diameter reduction was 4.5%. The mean values of the three micro-mechanical parameters fo, fc and fF from the study were found to be 0.0011, 0.118 and 0.368, respectively. The average void volume fraction at a location where the diameter reduction was 44% was found to be 0.00463 which is more than four times the initial void volume fraction. (author)

  9. 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 12±2 water molecules at 20oC and 6±2 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

  10. 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

  11. 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 ...

  12. 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.

  13. 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.

  14. Thermo-Hydro-Mechanical Evolution of Transport Properties in Porous Media: From Laboratory to the Groß-Schönebeck Geothermal Reservoir.

    Science.gov (United States)

    Jacquey, Antoine; Cacace, Mauro; Blöcher, 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, Blöcher 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 Groß-Schönebeck 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.

  15. Auxin apical control of the auxin polar transport and its oscillation - a suggested cellular transduction mechanism

    Directory of Open Access Journals (Sweden)

    Tomasz J. Wodzicki

    2014-02-01

    Full Text Available The proposed hypothesis concerns the transduction of auxin molecular signals arriving from the apoplast at the plasma membrane or recognized by the proteineous receptors of the responding cell, to the concentration gradients oscillating in the supracellular space, associated usually with the specific plant growth and differentiation. Acting as an agonist from outside the target cell auxin stimulates in this cell: (1 the liberation of auxin from the cytosolic pool of its conjugates directly into the basipetal efflux; (2 the synthesis of new auxin which restores the cytosolic reserve of auxin conjugates. The functioning of such a system may be effective in a series of processes initiated by the changing concentration of cytosolic calcium. The hypothesis suggests a molecular mechanism for the development and effective operation of the morphogenetic field in the supracellular space of the plant body, such as the field resulting from auxin waves discovered in cambium.

  16. 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.

  17. Seismic valve as the main mechanism for sedimentary fluid entrapment within extensional basin: example of the Lodève Permian Basin (Hérault, 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 Lodève Permian Basin (Hérault, 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 230°C, 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.

  18. Charge transport mechanism and the effects of device temperature on electrical parameters of Au/ZnPc/N-Si structures

    International Nuclear Information System (INIS)

    Gold/Zinc Phthalocyanine/n-Si metal semiconductor contact with organic interfacial layer have been developed and characterized by Current-Voltage-Temperature (I-V-T) measurements, to study its junction and charge transport properties. The junction parameters, of diode ideality factor (n), barrier height (phi/sub b/) and series resistance (R/sub S/), of the device are found to shift with device temperature. The barrier height and the diode ideality factor are found to increase and the series resistance is found to decrease with increasing device temperature. The activation energy of the charge carriers is found to be 44 MeV and the peak of interface state energy distribution curves is found to shift in terms of Ess-Ev value from 0.582 eV to 0.776 eV with increasing device temperature. The data analysis implies that the Fermi level of the organic interfacial layer shifts as function of device temperature by 100 MeV in the device temperature range of 283K to 343K. In terms of dominant conduction mechanism, the I-V-T data analysis confirms the fit of data to the relationship log (IV/sup 4/) proportional to V/sup 1/2/ for higher device temperatures and log Poole-Frenkel type is found to be the dominant conduction mechanism for the hybrid device. (author)

  19. Stepwise substrate translocation mechanism revealed by free energy calculations of doxorubicin in the multidrug transporter AcrB.

    Science.gov (United States)

    Zuo, Zhicheng; Wang, Beibei; Weng, Jingwei; Wang, Wenning

    2015-01-01

    AcrB is the inner membrane transporter of the tripartite multidrug efflux pump AcrAB-TolC in E. coli, which poses a major obstacle to the treatment of bacterial infections. X-ray structures have identified two types of substrate-binding pockets in the porter domains of AcrB trimer: the proximal binding pocket (PBP) and the distal binding pocket (DBP), and suggest a functional rotating mechanism in which each protomer cycles consecutively through three distinct conformational states (access, binding and extrusion). However, the details of substrate binding and translocation between the binding pockets remain elusive. In this work, we performed atomic simulations to obtain the free energy profile of the translocation of an antibiotic drug doxorubicin (DOX) inside AcrB. Our simulation indicates that DOX binds at the PBP and DBP with comparable affinities in the binding state protomer, and overcomes a 3?kcal/mol energy barrier to transit between them. Obvious conformational changes including closing of the PC1/PC2 cleft and shrinking of the DBP were observed upon DOX binding in the PBP, resulting in an intermediate state between the access and binding states. Taken together, the simulation results reveal a detailed stepwise substrate binding and translocation process in the framework of functional rotating mechanism. PMID:26365278

  20. Stepwise substrate translocation mechanism revealed by free energy calculations of doxorubicin in the multidrug transporter AcrB

    Science.gov (United States)

    Zuo, Zhicheng; Weng, Jingwei; Wang, Wenning

    2015-01-01

    AcrB is the inner membrane transporter of the tripartite multidrug efflux pump AcrAB-TolC in E. coli, which poses a major obstacle to the treatment of bacterial infections. X-ray structures have identified two types of substrate-binding pockets in the porter domains of AcrB trimer: the proximal binding pocket (PBP) and the distal binding pocket (DBP), and suggest a functional rotating mechanism in which each protomer cycles consecutively through three distinct conformational states (access, binding and extrusion). However, the details of substrate binding and translocation between the binding pockets remain elusive. In this work, we performed atomic simulations to obtain the free energy profile of the translocation of an antibiotic drug doxorubicin (DOX) inside AcrB. Our simulation indicates that DOX binds at the PBP and DBP with comparable affinities in the binding state protomer, and overcomes a 3?kcal/mol energy barrier to transit between them. Obvious conformational changes including closing of the PC1/PC2 cleft and shrinking of the DBP were observed upon DOX binding in the PBP, resulting in an intermediate state between the access and binding states. Taken together, the simulation results reveal a detailed stepwise substrate binding and translocation process in the framework of functional rotating mechanism. PMID:26365278

  1. Theoretical study on mechanical and electron-transport properties of conjugated molecular junctions with carboxylic or methyl sulfide links

    Energy Technology Data Exchange (ETDEWEB)

    Bao, De-Liang; Liu, Ran [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Leng, Jian-Cai [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); School of Science, Qilu University of Technology, Jinan 250353 (China); Zuo, Xi; Jiao, Yang [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Li, Zong-Liang, E-mail: lizongliang@sdnu.edu.cn [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Wang, Chuan-Kui [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)

    2014-03-01

    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 0.6±0.1 nN as experiment probed, which is much smaller than the force to break COO{sup ?}–Au bond. The COO{sup ?} group strongly influenced on M1 molecular junction and further strengthened SMe–Au bond at the other end of the junction. The M3 junction is less stable because the CH{sub 3} group linked to COO group destroyed the mechanical stability of COO–Au 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.

  2. Current transport mechanisms in CdS and Cd0.8NI0.2S thin films

    International Nuclear Information System (INIS)

    CdS and Cd0.8Ni0.2S thin films were deposited by Ultrasonic Spray Pyrolysis (USP) technique at 300±5 #Celsius# substrate temperature. The current transport mechanisms in polycrystalline CdS and Cd0.8Ni0.2S thin films were studied for the temperature range 140-425 K and 70-425 K, respectively. It was seen that CdS films were thermally activated and have the activation energy of 14.4 meV at temperatures between 140-205 K and the energy of traps like donor of 0.64 eV at temperatures between 265-425 K. These energy values were considerable lower for Cd0.8Ni0.2S thin films. The conductivity data for the high temperature region was analyzed using Seto's model of thermionic emission. At low temperatures it was found that tunneling of carriers through the potential barrier contributes to the conductivity. The space-charge limited (SCL) current mechanisms were also investigated to support the existence of traps

  3. THE MAIN PROBLEMS IN THE PROCESS OF ESTABLISHMENT OF PUBLIC COUNCILS AT THE FEDERAL EXECUTIVE BODIES OF THE RUSSIAN FEDERATION AS A MECHANISM OF PUBLIC CONTROL

    Directory of Open Access Journals (Sweden)

    Liliya Anatol’evna Bespalaya

    2015-08-01

    Full Text Available The article is devoted to the analysis of the organization and activity of Public councils at Federal executive authorities as social institutes of the civil society and the structure of social control of the power institutes which is formed in our country.The main purpose of this article consisted in research of the principles of formation of these social institutes, their powers, positive and negative aspects of their activity and dynamics, beginning from the moment of attempts of their introduction within Administrative reform in the country and then in the following laws aimed at improving the institutions of social control over the authorities.In article it is noted that process of reforming of public councils is only at the initial stage. However these structures possess the considerable potential of growth of opportunities for implementation of effective control and monitoring of authorities. This situation is possible only in case of the solving problems and difficulties in the course of their institutionalization and at adjustment of mutual dialogue between the state and civil society.

  4. 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)

  5. High CO2 emissions through porous media: Transport mechanisms and implications for flux measurement and fractionation

    Science.gov (United States)

    Evans, William C.; Sorey, M.L.; Kennedy, B.M.; Stonestrom, D.A.; Rogie, J.D.; Shuster, D.L.

    2001-01-01

    Diffuse emissions of CO2 are known to be large around some volcanoes and hydrothermal areas. Accumulation-chamber measurements of CO2 flux are increasingly used to estimate the total magmatic or metamorphic CO2 released from such areas. To assess the performance of accumulation chamber systems at fluxes one to three orders of magnitude higher than normally encountered in soil respiration studies, a test system was constructed in the laboratory where known fluxes could be maintained through dry sand. Steady-state gas concentration profiles and fractionation effects observed in the 30-cm sand column nearly match those predicted by the Stefan-Maxwell equations, indicating that the test system was functioning successfully as a uniform porous medium. Eight groups of investigators tested their accumulation chamber equipment, all configured with continuous infrared gas analyzers (IRGA), in this system. Over a flux range of ~ 200-12,000 g m-2 day-1, 90% of their 203 flux measurements were 0-25% lower than the imposed flux with a mean difference of - 12.5%. Although this difference would seem to be within the range of acceptability for many geologic investigations, some potential sources for larger errors were discovered. A steady-state pressure gradient of -20 Pa/m was measured in the sand column at a flux of 11,200 g m-2 day-1. The derived permeability (50 darcies) was used in the dusty-gas model (DGM) of transport to quantify various diffusive and viscous flux components. These calculations were used to demonstrate that accumulation chambers, in addition to reducing the underlying diffusive gradient, severely disrupt the steady-state pressure gradient. The resultant diversion of the net gas flow is probably responsible for the systematically low flux measurements. It was also shown that the fractionating effects of a viscous CO2 efflux against a diffusive influx of air will have a major impact on some important geochemical indicators, such as N2/Ar, ??15N-N2, and 4He/22Ne. Published by Elsevier Science B.V.

  6. A hopping mechanism for cargo transport by molecular motors in crowded microtubules

    CERN Document Server

    Goldman, Carla

    2010-01-01

    Most models designed to study the bidirectional movement of cargos as they are driven by molecular motors rely on the idea that motors of different polarities can be coordinated by external agents if arranged into a motor-cargo complex to perform the necessary work [gross04]. Although these models have provided us with important insights into these phenomena, there are still many unanswered questions regarding the mechanisms through which the movement of the complex takes place on crowded microtubules. For example (i) how does cargo-binding affect motor motility? and in connection with that - (ii) how does the presence of other motors (and also other cargos) on the microtubule affect the motility of the motor-cargo complex? We discuss these questions from a different perspective. The movement of a cargo is conceived here as a hopping process resulting from the transference of cargo between neighboring motors. In the light of this, we examine the conditions under which cargo might display bidirectional movemen...

  7. Study on Transport and Mechanical Properties of La and Ce Double Filled p-type Skutterudites

    Science.gov (United States)

    Dahal, Tulashi; Gahalwat, Sonika; Jie, Qing; Kim, Hee Seok; Dahal, Keshab; Liu, Weishu; Lan, Yucheng; White, Kenneth; Ren, Zhifeng; Ren's Group Team

    2015-03-01

    Optimizing the thermoelectric performance of p-type skutterudites is extremely challenging due to several factors such as low Seebeck voltage and bipolar contribution in electrical and thermal conductivity at elevated temperature, leading to small ZTvalue. In this work, we report improved thermoelectric performance of La and Ce double filled p-type skutterudites by melting-quenching-annealing-ball milling-hot pressing. The observed high power factor (~35 ?W cm-1 K-2 at 500 °C) and low thermal conductivity (~2.5 W m-1 K-1 at 500 °C) leads to a peak ZT about 1.1 in the optimized composition. With a ?T of 475 °C between heat source and sink, the estimated output power density in the best sample is ~8 W cm-2. The nano-indentation experiment reveals that the hardness and Young's modulus of elasticity of the sample is much better than Bi2Te3 and PbTe-based samples, indicating skutterudites is suitable for practical applications where mechanical strength is also important. U.S. Department of Energy.

  8. Electronic parameters and carrier transport mechanism of high-barrier Se Schottky contacts to n-type GaN

    Science.gov (United States)

    Rajagopal Reddy, V.; Janardhanam, V.; Ju, Jin-Woo; Yun, Hyung-Joong; Choi, Chel-Jong

    2014-02-01

    The electrical properties and current conduction mechanism of high-barrier Se/n-GaN Schottky diode have been investigated for the first time by current-voltage (I-V) and capacitance-voltage (C-V) measurements. High resolution transmission electron microscopy (HRTEM) results confirmed that no reaction occurs between Se film and the GaN substrate during Se deposition. Investigations reveal that the contact exhibited an excellent rectification behavior. The estimated barrier height of Se/n-GaN Schottky contact is 0.92 eV (I-V) and 1.27 eV (C-V) with the ideality factor of 1.10. The barrier height and series resistance are extracted by Cheung's functions. It is observed that the series resistance values obtained from Cheung's functions is in good agreement with each other. Further, capacitance-voltage measurements of the Se/n-GaN Schottky diode are carried out at different frequencies. The discrepancy between Schottky barrier heights obtained from I-V and C-V measurements is also explained. The AFM results showed that the surface morphology of the Se Schottky contacts on n-GaN is fairly smooth. The forward bias current transport mechanism of the Se/n-type GaN Schottky diode is determined by the log-log plot of I-V characteristics. Investigations reveal that the Schottky emission mechanism is found to be dominant in the reverse bias region of Se/n-GaN Schottky diode.

  9. Metabolismo do ferro: uma revisão sobre os principais mecanismos envolvidos em sua homeostase / Iron metabolism: an overview on the main mechanisms involved in its homeostasis

    Scientific Electronic Library Online (English)

    Helena Z. W., Grotto.

    2008-10-01

    Full Text Available Um perfeito sincronismo entre absorção, utilização e estoque de ferro é essencial para a manutenção do equilíbrio desse metal no organismo. Alterações nesses processos podem levar tanto à deficiência como ao seu acúmulo de ferro, duas situações com repercussões clínicas e laboratoriais importantes p [...] ara o paciente. Essa revisão aborda os diversos aspectos relacionados com a cinética do ferro, descrevendo as proteínas e mediadores nela envolvidos. Apresenta, ainda, como é feita a regulação intracelular e sistêmica do ferro que visa a manutenção de uma quantidade ótima de ferro para o metabolismo das células e, em especial, para uma perfeita hematopoiese.É discutido também o importante papel da hepcidina, como regulador da homeostase sistêmica. Será a apresenta da a relação entre a hepcidina e a resposta de fase aguda, e como as alterações na expressão da hepcidina podem contribuir com a fisiopatogênese da anemia de doença crônica. Abstract in english The perfect synchronism of intestinal absorption, use and storage of iron is critical for maintaining a balance in the organism. Disorders in these processes may lead either to iron deficiency or to iron overload, both of which have important clinical and laboratorial consequences for the patient. T [...] his review describes aspects related to iron metabolism and the participation of several proteins and mediators in these mechanisms. Moreover, intracellular and systemic regulation is responsible for providing the optimal iron concentration for cellular metabolism and, in particular, for adequate hematopoiesis. The relationship between hepcidin and acute phase response is presented and how changes in hepcidin expression may be related to the physiopathogenesis of anemia of chronic disease.

  10. Experience in the determination of the depth and of the transport mechanism of inhibitors in natural gas production plants using radioisotopes

    International Nuclear Information System (INIS)

    The method described made it possible for the first time to determine with sufficient accuracy the depth of the protective effect of solid inhibitors placed by means of tubings in natural gas wells. In the surface installations possible influences on the gas cleaning lines could be detected and prevented by elucidating the transport mechanism of the inhibitors. (author)

  11. Transport and Retention of TiO2 Rutile Nanoparticles in Saturated Porous Media at Low-Ionic-Strength Conditions: Measurements and Mechanisms

    Science.gov (United States)

    The mechanisms governing the transport and retention kinetics of titanium dioxide (TiO2, rutile) nanoparticle (NP) aggregates were investigated in saturated porous media. Experiments were carried out under a range of well-controlled ionic strength (from DI water up to 1 mM) and...

  12. Transport Experiments

    Science.gov (United States)

    Hall, Timothy M.; Wuebbles, Donald J.; Boering, Kristie A.; Eckman, Richard S.; Lerner, Jean; Plumb, R. Alan; Rind, David H.; Rinsland, Curtis P.; Waugh, Darryn W.; Wei, Chu-Feng

    1999-01-01

    MM II defined a series of experiments to better understand and characterize model transport and to assess the realism of this transport by comparison to observations. Measurements from aircraft, balloon, and satellite, not yet available at the time of MM I [Prather and Remsberg, 1993], provide new and stringent constraints on model transport, and address the limits of our transport modeling abilities. Simulations of the idealized tracers the age spectrum, and propagating boundary conditions, and conserved HSCT-like emissions probe the relative roles of different model transport mechanisms, while simulations of SF6 and C02 make the connection to observations. Some of the tracers are related, and transport diagnostics such as the mean age can be derived from more than one of the experiments for comparison to observations. The goals of the transport experiments are: (1) To isolate the effects of transport in models from other processes; (2) To assess model transport for realistic tracers (such as SF6 and C02) for comparison to observations; (3) To use certain idealized tracers to isolate model mechanisms and relationships to atmospheric chemical perturbations; (4) To identify strengths and weaknesses of the treatment of transport processes in the models; (5) To relate evaluated shortcomings to aspects of model formulation. The following section are included:Executive Summary, Introduction, Age Spectrum, Observation, Tropical Transport in Models, Global Mean Age in Models, Source-Transport Covariance, HSCT "ANOY" Tracer Distributions, and Summary and Conclusions.

  13. Adiabatic and diabatic aerosol transport to the Jungfraujoch

    Energy Technology Data Exchange (ETDEWEB)

    Lugauer, M.; Baltensperger, U.; Furger, M.; Jost, D.T.; Schwikowski, M.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Synoptic scale vertical motion, here detected by the geopotential height of the 500 hPa surface, mainly accounts for the aerosol transport to the Jungfraujoch in winter. In summer, diabatic convection provides the dominant vertical transport mechanism. Nevertheless, synoptic scale adiabatic motion still determines whether diabatic convection can develop. (author) 2 figs., 2 refs.

  14. Mechanisms Regulating Acid-Base Transporter Expression in Breast- and Pancreatic Cancer : Contributions to the Cancer Phenotype

    DEFF Research Database (Denmark)

    Gorbatenko, Andrej

    2015-01-01

    Breast cancer is the most commonly diagnosed cancer in women, and the second most frequent cause of death from cancer in women. Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest forms of cancer with only a 5% 5-year survival rate. Both types of cancer form solid tumors, 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 dealing with excess acid production. In this light, evidence accumulates on the importance of pH regulatory proteins to cancer cell survival and motility. Our group previously demonstrated upregulation of the Na+/HCO3 - co-transporter NBCn1 (SLC4A7) by a constitutively active form of HER2 receptor (p95HER2). In Paper 1 and Paper 3 we demonstrate mechanisms of p95HER2-dependent NBCn1 upregulation. Transcriptionally, NBCn1 expression is controlled by ERK1 and Akt1 kinases modulating Krüppel-like factor 4 (KLF4) transcriptional activity. Additionally, we show that other HER2 family members, when stimulated, are able to upregulate NBCn1 expression as well. Paper 3 demonstrates that p95HER2 further stabilizes NBCn1 mRNA, by preventing its downregulation through a 3’UTR region-dependent mechanism, probably involving miRNAs. In Paper 5 we investigate miRNA expression profiles induced by full-HER2 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-221/222 pathway. Paper 2 reviews current findings on two families of bicarbonate transporters – SLC4 and SLC26, in cancer. Moreover, using analysis of publicly available high-throughput data we hypothesize that expression and, perhaps, function, of SLC4 and SLC26 family members, as well as carbonic anhydrase (CA) II, IX and XII is cancer subtype specific. In Paper 4 we show that a3, subunit of another pH-regulatory protein complex - V-ATPase, is upregulated at the mRNA and protein level in a panel of PDAC cancer cell lines. We demonstrate the importance of the a3 subunit for proliferation and survival pathways, motility and invasion in PDAC cells. As increased expression of a3 was detected in every PDAC cell line tested, we propose a3 as a potential target for diagnostics and targeted therapy. Collectively, our findings demonstrate several novel mechanisms through which the expression of a pH-regulatory protein, NBCn1, can be controlled by an oncogene, p95HER2. Further, they reveal differences in small non-coding RNA (miRNA) expression profiles between full-length HER2 and its truncated p95HER2 form. And finally, we report a potential target for PDAC diagnostics and treatment

  15. Avaliação de danos mecânicos causados em banana "Nanicão" durante as etapas de beneficiamento, transporte e embalagem" / Mechanical damages caused in banana "Nanicão" in the improvement process, packing and transport

    Scientific Electronic Library Online (English)

    Juliana, Sanches; Paulo A. M., Leal; José H., Saravali; Silvia, Antoniali.

    2004-04-01

    Full Text Available Este estudo teve como objetivo a avaliação de danos mecânicos ocorridos na banana "Nanicão" durante o processo de beneficiamento, transporte, embalagem e distribuição, identificando os prováveis pontos críticos. Avaliaram-se os danos mecânicos causados após o transporte, despistilagem e primeira des [...] penca; limpeza e classificação; acondicionamento nas embalagens e transporte, e amadurecimento. As embalagens estudadas foram: embalagem de madeira torito (18 kg), madeira tipo ½ caixa (13 kg) e papelão (18 kg). Verificou-se que, na etapa de acondicionamento e transporte das frutas até o centro de distribuição, duplicaram os defeitos leves e os defeitos graves quintuplicaram, causando podridões após a climatização. A embalagem de papelão não suportou o empilhamento e apresentou deformações, que resultaram no amassamento das frutas que estavam nas embalagens inferiores e no aumento significativo dos defeitos graves. As frutas acondicionadas nas embalagens envolvidas pelo plástico bolha apresentaram menos danos graves quando comparadas às demais embalagens, sem o plástico. Abstract in english This study had as objective the evaluation of mechanical damages occurred in banana "Nanicão" during the improvement process, packing and distribution, identifying the probable critical points. The mechanical damages caused by transport, first cleaning; cleanness and sorting; preservation in the pac [...] king, transport, and mature were evaluated. The studied packing had been: torito wooden packing (18 kg), wood type ½ box, (13 kg) and cardboard (18 kg). The stage of preservation and transport of the fruits to the distribution center duplicated the light defects and quintupled the serious defects, causing rottenness after the acclimatization. The cardboard packing did not support the piling up and presented deformations, that resulted in the kneading the fruits of the inferior packing, causing a significant increase of the serious defects. The fruits conditioned in the involved packing of plastic bubble had presented an inferior number of serious damages when compared with the others packing, without the plastic.

  16. Avaliação de danos mecânicos causados em banana "Nanicão" durante as etapas de beneficiamento, transporte e embalagem" Mechanical damages caused in banana "Nanicão" in the improvement process, packing and transport

    Directory of Open Access Journals (Sweden)

    Juliana Sanches

    2004-04-01

    Full Text Available Este estudo teve como objetivo a avaliação de danos mecânicos ocorridos na banana "Nanicão" durante o processo de beneficiamento, transporte, embalagem e distribuição, identificando os prováveis pontos críticos. Avaliaram-se os danos mecânicos causados após o transporte, despistilagem e primeira despenca; limpeza e classificação; acondicionamento nas embalagens e transporte, e amadurecimento. As embalagens estudadas foram: embalagem de madeira torito (18 kg, madeira tipo ½ caixa (13 kg e papelão (18 kg. Verificou-se que, na etapa de acondicionamento e transporte das frutas até o centro de distribuição, duplicaram os defeitos leves e os defeitos graves quintuplicaram, causando podridões após a climatização. A embalagem de papelão não suportou o empilhamento e apresentou deformações, que resultaram no amassamento das frutas que estavam nas embalagens inferiores e no aumento significativo dos defeitos graves. As frutas acondicionadas nas embalagens envolvidas pelo plástico bolha apresentaram menos danos graves quando comparadas às demais embalagens, sem o plástico.This study had as objective the evaluation of mechanical damages occurred in banana "Nanicão" during the improvement process, packing and distribution, identifying the probable critical points. The mechanical damages caused by transport, first cleaning; cleanness and sorting; preservation in the packing, transport, and mature were evaluated. The studied packing had been: torito wooden packing (18 kg, wood type ½ box, (13 kg and cardboard (18 kg. The stage of preservation and transport of the fruits to the distribution center duplicated the light defects and quintupled the serious defects, causing rottenness after the acclimatization. The cardboard packing did not support the piling up and presented deformations, that resulted in the kneading the fruits of the inferior packing, causing a significant increase of the serious defects. The fruits conditioned in the involved packing of plastic bubble had presented an inferior number of serious damages when compared with the others packing, without the plastic.

  17. Characterizing mechanisms of extracellular electron transport in sulfur and iron-oxidizing electrochemically active bacteria isolated from marine sediments

    Science.gov (United States)

    Rowe, A. R.; Bird, L. J.; Lam, B. R.; Nealson, K. H.

    2014-12-01

    Lithotrophic reactions, including the oxidation of mineral species, are often difficult to detect in environmental systems. This could be due to the nature of substrate or metabolite quantification or the rapid consumption of metabolic end products or intermediates by proximate biological or abiotic processes. Though recently genetic markers have been applied to detecting these processes in environmental systems, our knowledge of lithotrophic markers are limited to those processes catalyzed by organisms that have been cultured and physiologically characterized. Here we describe the use of electrochemical enrichment techniques to isolate marine sediment-dwelling microbes capable of the oxidation or insoluble forms of iron and sulfur including both the elemental species. All the organisms isolated fall within the Alphaproteobacteria and Gammaproteobacteria and are capable of acquiring electrons from an electrode while using either oxygen or nitrate as a terminal electron acceptor. Electrochemical analysis of these microbes has demonstrated that, though they have similar geochemical abilities (either sulfur or iron oxidation), they likely utilize different biochemical mechanisms demonstrated by the variability in dominant electron transfer modes or interactions (i.e., biofilm, planktonic or mediator facilitated interactions) and the wide range of midpoint potentials observed for dominant redox active cellular components (ranging from -293 to +50 mV vs. Ag/AgCl). For example, organisms isolated on elemental sulfur tended to have higher midpoint potentials than iron-oxidizing microbes. A variety of techniques are currently being applied to understanding the different mechanisms of extracellular electron transport for oxidizing an electrode or corresponding insoluble electron donor including both genomic and genetic manipulation experiments. The insight gained from these experiments is not limited to the physiology of the organisms isolated but will also aid in identification of genetic targets to better understand the ecologic importance of lithotrophs and the role solid substrates may play in their metabolism.

  18. Predicted Structure, Thermo-Mechanical Properties and Li Ion Transport in LiAlF4 Glass

    Energy Technology Data Exchange (ETDEWEB)

    Stechert, T. R.; Rushton, M. J. D.; Grimes, R. W.; Dillon, A. C.

    2012-08-15

    Materials with the LiAlF{sub 4} composition are of interest as protective electrode coatings in Li ion battery applications due to their high cationic conductivity. Here classical molecular dynamics calculations are used to produce amorphous model structures by simulating a quench from the molten state. These are analysed in terms of their individual pair correlation functions and atomic coordination environments. This indicates that amorphous LiAlF{sub 4} is formed of a network of corner sharing AlF{sub 6} octahedra. Li ions are distributed within this network, primarily associated with non-bridging fluorine atoms. The nature of the octahedral network is further analysed through intra- and interpolyhedral bond angle distributions and the relative populations of bridging and non-bridging fluorine ions are calculated. Network topology is considered through the use of ring statistics, which indicates that, although topologically well connected, LiAlF{sub 4} contains an appreciable number of corner-linked branch-like AlF{sub 6} chains. Thermal expansion values are determined above and below the predicted glass transition temperature of 1340 K. Finally, movement of Li ions within the network is examined with predictions of the mean squared displacements, diffusion coefficients and Li ion activation energy. Different regimes for lithium ion movement are identified, with both diffusive and sessile Li ions observed. For migrating ions, a typical trajectory is illustrated and discussed in terms of a hopping mechanism for Li transport.

  19. Hydro-mechanical coupling and transport in Meuse/Haute-Marne argillite: experimental and multi-scale approaches

    International Nuclear Information System (INIS)

    This thesis deals with the hydro-mechanical behaviour of argillite. Classical Biot theory is shown to be badly adapted to the case of argillite. An original state equation is then built by use of homogenization tools, and takes into account the microstructure of argillite as well as physical phenomena happening inside the material, like the swelling overpressure inside the clay particles or the capillary effects in the porous network. This state equation explains some experiments which were not by the classical Biot theory. It is then improved by integrating the experimental data that are the dependency of the elasticity tensor with the saturation degree and the existence of a porosity surrounding the inclusions. Combined with the monitoring of length variation under hydric loading, this relevant state equation permits one to determine the Biot tensor of argillite. Since this state equation is coupled with the hydric state of the material, one is interested in modelling the variation of the saturation degree during a drying process. Two transport models are studied and compared, then a model for the porous network is proposed in order to explain the unusual permeability measurements. (author)

  20. Geoinformatics for intelligent transportation

    CERN Document Server

    Ivan, Igor; Jiang, Bin; Horák, Jirí; Haworth, James; Inspektor, Tomas

    2014-01-01

    The aim of the book is to present and discuss new methods, issues and challenges involved in geoinformatics' contribution to making transportation more intelligent, efficient and human-friendly. It covers a wide range of topics related to transportation and geoinformatics. The themes are divided into four main sections: Transport modeling, Sensor data and services, Intelligent transport systems, and Transport planning and accessibility.

  1. 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

  2. The influence of hydrogen on the chemical, mechanical, optical/electronic, and electrical transport properties of amorphous hydrogenated boron carbide

    Science.gov (United States)

    Nordell, Bradley J.; Karki, Sudarshan; Nguyen, Thuong D.; Rulis, Paul; Caruso, A. N.; Purohit, Sudhaunshu S.; Li, Han; King, Sean W.; Dutta, Dhanadeep; Gidley, David; Lanford, William A.; Paquette, Michelle M.

    2015-07-01

    Because of its high electrical resistivity, low dielectric constant (?), high thermal neutron capture cross section, and robust chemical, thermal, and mechanical properties, amorphous hydrogenated boron carbide (a-BxC:Hy) has garnered interest as a material for low-? dielectric and solid-state neutron detection applications. Herein, we investigate the relationships between chemical structure (atomic concentration B, C, H, and O), physical/mechanical properties (density, porosity, hardness, and Young's modulus), electronic structure [band gap, Urbach energy (EU), and Tauc parameter (B1/2)], optical/dielectric properties (frequency-dependent dielectric constant), and electrical transport properties (resistivity and leakage current) through the analysis of a large series of a-BxC:Hy thin films grown by plasma-enhanced chemical vapor deposition from ortho-carborane. The resulting films exhibit a wide range of properties including H concentration from 10% to 45%, density from 0.9 to 2.3 g/cm3, Young's modulus from 10 to 340 GPa, band gap from 1.7 to 3.8 eV, Urbach energy from 0.1 to 0.7 eV, dielectric constant from 3.1 to 7.6, and electrical resistivity from 1010 to 1015 ? cm. Hydrogen concentration is found to correlate directly with thin-film density, and both are used to map and explain the other material properties. Hardness and Young's modulus exhibit a direct power law relationship with density above ˜1.3 g/cm3 (or below ˜35% H), below which they plateau, providing evidence for a rigidity percolation threshold. An increase in band gap and decrease in dielectric constant with increasing H concentration are explained by a decrease in network connectivity as well as mass/electron density. An increase in disorder, as measured by the parameters EU and B1/2, with increasing H concentration is explained by the release of strain in the network and associated decrease in structural disorder. All of these correlations in a-BxC:Hy are found to be very similar to those observed in amorphous hydrogenated silicon (a-Si:H), which suggests parallels between the influence of hydrogenation on their material properties and possible avenues for optimization. Finally, an increase in electrical resistivity with increasing H at <35 at. % H concentration is explained, not by disorder as in a-Si:H, but rather by a lower rate of hopping associated with a lower density of sites, assuming a variable range hopping mechanism interpreted in the framework of percolation theory.

  3. Reactive Transport Modelling of CO2 Storage in Saline Aquifers to Elucidate Fundamental Processes, Trapping Mechanisms, and Sequestration Partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J W; Nitao, J J; Knauss, K G

    2004-07-26

    The ultimate fate of CO{sub 2} injected into saline aquifers for environmental isolation is governed by three interdependent yet conceptually distinct processes: CO{sub 2} migration as a buoyant immiscible fluid phase, direct chemical interaction of this rising plume with ambient saline waters, and its indirect chemical interaction with aquifer and cap-rock minerals through the aqueous wetting phase. Each process is directly linked to a corresponding trapping mechanism: immiscible plume migration to hydrodynamic trapping, plume-water interaction to solubility trapping, and plume-mineral interaction to mineral trapping. In this study, reactive transport modeling of CO{sub 2} storage in a shale-capped sandstone aquifer at Sleipner has elucidated and established key parametric dependencies of these fundamental processes, the associated trapping mechanisms, and sequestration partitioning among them during consecutive 10-year prograde (active-injection) and retrograde (post-injection) regimes. Intra-aquifer permeability structure controls the path of immiscible CO{sub 2} migration, thereby establishing the spatial framework of plume-aquifer interaction and the potential effectiveness of solubility and mineral trapping. Inter-bedded thin shales--which occur at Sleipner--retard vertical and promote lateral plume migration, thereby significantly expanding this framework and enhancing this potential. Actual efficacy of these trapping mechanisms is determined by compositional characteristics of the aquifer and cap rock: the degree of solubility trapping decreases with increasing formation-water salinity, while that of mineral trapping is proportional to the bulk concentration of carbonate-forming elements--principally Fe, Mg, Ca, Na, and Al. In the near-field environment of Sleipner-like settings, 80-85% by mass of injected CO{sub 2} remains and migrates as an immiscible fluid phase, 15-20% dissolves into formation waters, and less than 1% precipitates as carbonate minerals. This partitioning defines the relative effectiveness of hydrodynamic, solubility, and mineral trapping on a mass basis. Seemingly inconsequential, mineral trapping has enormous strategic significance: it maintains injectivity, delineates the storage volume, and improves cap-rock integrity. We have identified four distinct mechanisms: dawsonite [NaAlCO{sub 3}(OH){sub 2}] cementation occurs throughout the intra-aquifer plume, while calcite-group carbonates [principally, (Fe,Mg,Ca)CO{sub 3}] precipitate via disparate processes along lateral and upper plume margins, and by yet another process within inter-bedded and cap-rock shales. The coupled mineral dissolution/precipitation reaction associated with each mechanism reduces local porosity and permeability. For Sleipner-like settings, the magnitude of such reduction for dawsonite cementation is near negligible; hence, this process effectively maintains initial CO{sub 2} injectivity. Of similarly small magnitude is the reduction associated with formation of carbonate rind along upper and lateral plume boundaries; these processes effectively delineate the CO{sub 2} storage volume, and for saline aquifers anomalously rich in Fe-Mg-Ca may partially self-seal the plume. Porosity and permeability reduction is most extreme within shales, because their clay-rich mineralogy defines bulk Fe-Mg concentrations much greater than those of saline aquifers. In the basal cap-rock shale of our models, these reductions amount to 4.5 and 13%, respectively, after the prograde regime. During the retrograde phase, residual saturation of immiscible CO{sub 2} maintains the prograde extent of solubility trapping while continuously enhancing that of mineral trapping. At the close of our 20-year simulations, initial porosity and permeability of the basal cap-rock shale have been reduced by 8 and 22%, respectively. Extrapolating to hypothetical complete consumption of Fe-Mg-bearing shale minerals (here, 10 vol.% Mg-chlorite) yields an ultimate reduction of about 52 and 90%, respectively, after 130 years. Hence, the most crucial strategic impa

  4. Unique Aeolian Transport Mechanisms on Mars: Respective Roles of Percussive and Repercussive Grain Populations in the Sediment Load

    Science.gov (United States)

    Marshall, John R.

    1999-09-01

    Experiments show that when sand-size grains impact a sediment surface with energy levels commensurate for Mars, small craters are formed by the ejection of several hundred grains from the bed. The experiments were conducted with a modified crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism. Individual grains of sand could be fired at loose sand targets to observe ballistic effects unhindered by aerodynamic mobilization of the bed. Impact trajectories simulated the saltation process on dune surfaces. Impact craters were not elongated despite glancing (15 deg.) bed impact; the craters were very close to being circular. High-speed photography showed them to grow in both diameter and depth after the impactor had ricochetted from the crater site. The delayed response of the bed was "explosive" in nature, and created a miniature ejecta curtain spreading upward and outward for many centimeters for impact of 100-300 micron-diameter grains into similar material. This behavior is explained by deposition of elastic energy in the bed by the "percussive" grain. Impact creates a subsurface stress regime or "quasi-Boussinesq" compression field. Elastic recovery of the bed occurs by dilatancy; shear stresses suddenly convert the grains to open packing and they consequently become forcefully ejected from the site. Random jostling of the grains causes radial homogenization of stress vectors and a resulting circular crater. A stress model based on repercussive bed dilatancy and interparticle adhesive forces (for smaller grains) predicts, to first order, the observed crater volumes for various impact conditions. On earth, only a few grains are mobilized by a percussive saltating grain; some grains are "knudged" along the ground, and some are partly expelled on short trajectories. These motions constitute reptation transport. On Mars, saltation and reptation become indistinct: secondary or "repercussive" trajectories have sufficient vertical impulse to create a dense saltation population of many tens or hundreds of grains for each single high-speed saltation percussion of the bed. Impact cascading will lead to near-surface distortion of the boundary layer, and choked flow formed by a dense "slurry" of sand, with the majority of grains mobilized by repercussive forces rather than by aerodynamic lift. This proceeds until a fully-matured transport layer imposes self- limitations as grain-population density constrains the free-path motion of individual grains.

  5. Unique Aeolian Transport Mechanisms on Mars: Respective Roles of Percussive and Repercussive Grain Populations in the Sediment Load

    Science.gov (United States)

    Marshall, John R.

    1999-01-01

    Experiments show that when sand-size grains impact a sediment surface with energy levels commensurate for Mars, small craters are formed by the ejection of several hundred grains from the bed. The experiments were conducted with a modified crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism. Individual grains of sand could be fired at loose sand targets to observe ballistic effects unhindered by aerodynamic mobilization of the bed. Impact trajectories simulated the saltation process on dune surfaces. Impact craters were not elongated despite glancing (15 deg.) bed impact; the craters were very close to being circular. High-speed photography showed them to grow in both diameter and depth after the impactor had ricochetted from the crater site. The delayed response of the bed was "explosive" in nature, and created a miniature ejecta curtain spreading upward and outward for many centimeters for impact of 100-300 micron-diameter grains into similar material. This behavior is explained by deposition of elastic energy in the bed by the "percussive" grain. Impact creates a subsurface stress regime or "quasi-Boussinesq" compression field. Elastic recovery of the bed occurs by dilatancy; shear stresses suddenly convert the grains to open packing and they consequently become forcefully ejected from the site. Random jostling of the grains causes radial homogenization of stress vectors and a resulting circular crater. A stress model based on repercussive bed dilatancy and interparticle adhesive forces (for smaller grains) predicts, to first order, the observed crater volumes for various impact conditions. On earth, only a few grains are mobilized by a percussive saltating grain; some grains are "knudged" along the ground, and some are partly expelled on short trajectories. These motions constitute reptation transport. On Mars, saltation and reptation become indistinct: secondary or "repercussive" trajectories have sufficient vertical impulse to create a dense saltation population of many tens or hundreds of grains for each single high-speed saltation percussion of the bed. Impact cascading will lead to near-surface distortion of the boundary layer, and choked flow formed by a dense "slurry" of sand, with the majority of grains mobilized by repercussive forces rather than by aerodynamic lift. This proceeds until a fully-matured transport layer imposes self- limitations as grain-population density constrains the free-path motion of individual grains.

  6. Sistemas primários de transporte de prótons integram os mecanismos de desintoxicação do mesotrione em plantas de milho Proton transport primary systems used as mechanisms of mesotrione detoxification in corn plants

    Directory of Open Access Journals (Sweden)

    J. Ogliari

    2009-01-01

    Full Text Available O mesotrione é um dos mais efetivos herbicidas desenvolvidos para o controle de uma ampla gama de plantas daninhas que infestam campos de milho (Zea mays. Todavia, as bases bioquímicas e moleculares da tolerância das plantas de milho a esse herbicida ainda não foram estabelecidas. Para compreender os mecanismos de desintoxicação do mesotrione em plantas de milho, foram analisadas as atividades dos principais sistemas primários de transporte de prótons (íons H+ das membranas plasmática e vacuolar (H+-ATPases do tipo P e V e H+-PPases de células de diferentes tecidos de plantas tratadas após aplicação do herbicida em pós-emergência. Para isso, foram realizados procedimentos de fracionamento celular, de tecidos radiculares, foliares e do caule, por centrifugação diferencial e purificação de vesículas membranares em gradiente de densidade de sacarose. Os ensaios enzimáticos das atividades hidrolíticas das três bombas de H+ foram realizados aplicando-se um método colorimétrico para medir o fosfato liberado das hidrólises dos substratos: adenosina-5'-trifosfato (ATP e pirofosfato (PPi. Parâmetros fotossintéticos foram analisados como marcadores fisiológicos dos diferentes estádios da desintoxicação das plantas. Essa análise demonstrou que o tratamento com mesotrione promoveu uma redução na taxa fotossintética e na relação Fv/Fm no terceiro dia após aplicação (DAA, mas não afetou significativamente a fotossíntese a partir do quinto DAA. Nos três tecidos analisados, raiz, folha e caule, aos 3 DAA, foi observado forte estímulo da atividade da H+-PPase vacuolar, a qual variou de cerca de 100 a 600%. Essa forte ativação foi reduzida significativamente aos 7 DAA, mas permaneceu pelo menos duas vezes maior com relação ao controle. Por sua vez, as H+-ATPases das membranas plasmática e vacuolar foram bem menos moduladas pelo tratamento com o herbicida, apresentando estimulações e inibições que não variaram mais do que 20 a 60% das atividades obtidas em vesículas de membranas oriundas de plantas não tratadas (controle. Os resultados demonstraram que o mesotrione promove uma ativação diferencial dos principais sistemas primários de transporte de H+, indicando que essas bombas iônicas são enzimas transportadoras essenciais aos mecanismos relacionados com o processo de desintoxicação das plantas de milho, possivelmente ao energizar a compartimentalização das moléculas do herbicida mesotrione no vacúolo ou a exceção celular através das membranas plasmáticas.The herbicide Mesotrione herbicides are very effective in the control of a wide range of weeds that infest corn (Zea mays fields. However, the biochemical and molecular bases of corn seedling tolerance to this herbicide have not been established so far. To understand the mechanisms of mesotrione detoxification in corn plants, the activities of the main primary proton (H+ ion transport systems of the vacuolar and plasma membranes (H+-ATPases V- and P-types, and H+-PPase of the cells from different tissues were analyzed, after post-emergence herbicide application. Thus, cell fractionation procedures on root, leaf and mesocotyl tissues were performed using differential membrane vesicle centrifugation and purification in sucrose density gradient. Hydrolytic activities of the proton pumps were measured by using a colorimetric method for phosphate released through enzymatic hydrolysis of the substrates adenosine-5'-triphosphate (ATP and pyrophosphate (PPi. Photosynthetic parameters were analyzed as physiological markers of the different stages of plant detoxification. Such analysis demonstrated that, three days after herbicide application (DAA, mesotrione induced a reduction in the photosynthetic rate and Fv/Fm ratio, but no significant effect could be found after the fifth DAA. These data suggest that the treatment with mesotrione promoted a spatial and temporal regulation of the H+ pump activities. In all the root, leaf and mesocotyl tisues analyzed, at three DAA, a strong stimulation of the vacuolar

  7. Sistemas primários de transporte de prótons integram os mecanismos de desintoxicação do mesotrione em plantas de milho / Proton transport primary systems used as mechanisms of mesotrione detoxification in corn plants

    Scientific Electronic Library Online (English)

    J., Ogliari; S.P., Freitas; A.C., Ramos; R.E., Bressan Smith; A.R., Façanha.

    Full Text Available O mesotrione é um dos mais efetivos herbicidas desenvolvidos para o controle de uma ampla gama de plantas daninhas que infestam campos de milho (Zea mays). Todavia, as bases bioquímicas e moleculares da tolerância das plantas de milho a esse herbicida ainda não foram estabelecidas. Para compreender [...] os mecanismos de desintoxicação do mesotrione em plantas de milho, foram analisadas as atividades dos principais sistemas primários de transporte de prótons (íons H+) das membranas plasmática e vacuolar (H+-ATPases do tipo P e V e H+-PPases) de células de diferentes tecidos de plantas tratadas após aplicação do herbicida em pós-emergência. Para isso, foram realizados procedimentos de fracionamento celular, de tecidos radiculares, foliares e do caule, por centrifugação diferencial e purificação de vesículas membranares em gradiente de densidade de sacarose. Os ensaios enzimáticos das atividades hidrolíticas das três bombas de H+ foram realizados aplicando-se um método colorimétrico para medir o fosfato liberado das hidrólises dos substratos: adenosina-5'-trifosfato (ATP) e pirofosfato (PPi). Parâmetros fotossintéticos foram analisados como marcadores fisiológicos dos diferentes estádios da desintoxicação das plantas. Essa análise demonstrou que o tratamento com mesotrione promoveu uma redução na taxa fotossintética e na relação Fv/Fm no terceiro dia após aplicação (DAA), mas não afetou significativamente a fotossíntese a partir do quinto DAA. Nos três tecidos analisados, raiz, folha e caule, aos 3 DAA, foi observado forte estímulo da atividade da H+-PPase vacuolar, a qual variou de cerca de 100 a 600%. Essa forte ativação foi reduzida significativamente aos 7 DAA, mas permaneceu pelo menos duas vezes maior com relação ao controle. Por sua vez, as H+-ATPases das membranas plasmática e vacuolar foram bem menos moduladas pelo tratamento com o herbicida, apresentando estimulações e inibições que não variaram mais do que 20 a 60% das atividades obtidas em vesículas de membranas oriundas de plantas não tratadas (controle). Os resultados demonstraram que o mesotrione promove uma ativação diferencial dos principais sistemas primários de transporte de H+, indicando que essas bombas iônicas são enzimas transportadoras essenciais aos mecanismos relacionados com o processo de desintoxicação das plantas de milho, possivelmente ao energizar a compartimentalização das moléculas do herbicida mesotrione no vacúolo ou a exceção celular através das membranas plasmáticas. Abstract in english The herbicide Mesotrione herbicides are very effective in the control of a wide range of weeds that infest corn (Zea mays) fields. However, the biochemical and molecular bases of corn seedling tolerance to this herbicide have not been established so far. To understand the mechanisms of mesotrione de [...] toxification in corn plants, the activities of the main primary proton (H+ ion) transport systems of the vacuolar and plasma membranes (H+-ATPases V- and P-types, and H+-PPase) of the cells from different tissues were analyzed, after post-emergence herbicide application. Thus, cell fractionation procedures on root, leaf and mesocotyl tissues were performed using differential membrane vesicle centrifugation and purification in sucrose density gradient. Hydrolytic activities of the proton pumps were measured by using a colorimetric method for phosphate released through enzymatic hydrolysis of the substrates adenosine-5'-triphosphate (ATP) and pyrophosphate (PPi). Photosynthetic parameters were analyzed as physiological markers of the different stages of plant detoxification. Such analysis demonstrated that, three days after herbicide application (DAA), mesotrione induced a reduction in the photosynthetic rate and Fv/Fm ratio, but no significant effect could be found after the fifth DAA. These data suggest that the treatment with mesotrione promoted a spatial and temporal regulation of the H+ pump activities. In all the root, leaf and mesocotyl tisues analyzed, at

  8. Functional Analysis of Arabidopsis Sucrose Transporters

    Energy Technology Data Exchange (ETDEWEB)

    John M. Ward

    2009-03-31

    Sucrose is the main photosynthetic product that is transported in the vasculature of plants. The long-distance transport of carbohydrates is required to support the growth and development of net-importing (sink) tissues such as fruit, seeds and roots. This project is focused on understanding the transport mechanism sucrose transporters (SUTs). These are proton-coupled sucrose uptake transporters (membrane proteins) that are required for transport of sucrose in the vasculature and uptake into sink tissues. The accomplishments of this project included: 1) the first analysis of substrate specificity for any SUT. This was accomplished using electrophysiology to analyze AtSUC2, a sucrose transporter from companion cells in Arabidopsis. 2) the first analysis of the transport activity for a monocot SUT. The transport kinetics and substrate specificity of HvSUT1 from barley were studied. 3) the first analysis of a sucrose transporter from sugarcane. and 4) the first analysis of transport activity of a sugar alcohol transporter homolog from plants, AtPLT5. During this period four primary research papers, funded directly by the project, were published in refereed journals. The characterization of several sucrose transporters was essential for the current effort in the analysis of structure/function for this gene family. In particular, the demonstration of strong differences in substrate specificity between type I and II SUTs was important to identify targets for site-directed mutagenesis.

  9. Concurrency in Main-Memory Database Systems

    OpenAIRE

    Mühe, Henrik

    2014-01-01

    The availability of terabytes of main-memory has sparked a renewed interest in main-memory database systems. In this thesis, we first determine the optimal mechanism for creating snapshots in main-memory systems which can be used to execute OLAP queries. Then, we introduce tentative execution, a mechanism which allows long-running transactions to be efficiently executed. Lastly, we describe our multi-tenancy approach which uses operating system mechanisms to enforce service level agreements.

  10. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  11. Rab1-dependent ER-Golgi transport dysfunction is a common pathogenic mechanism in SOD1, TDP-43 and FUS-associated ALS.

    Science.gov (United States)

    Soo, Kai Y; Halloran, Mark; Sundaramoorthy, Vinod; Parakh, Sonam; Toth, Reka P; Southam, Katherine A; McLean, Catriona A; Lock, Peter; King, Anna; Farg, Manal A; Atkin, Julie D

    2015-11-01

    Several diverse proteins are linked genetically/pathologically to neurodegeneration in amyotrophic lateral sclerosis (ALS) including SOD1, TDP-43 and FUS. Using a variety of cellular and biochemical techniques, we demonstrate that ALS-associated mutant TDP-43, FUS and SOD1 inhibit protein transport between the endoplasmic reticulum (ER) and Golgi apparatus in neuronal cells. ER-Golgi transport was also inhibited in embryonic cortical and motor neurons obtained from a widely used animal model (SOD1(G93A) mice), validating this mechanism as an early event in disease. Each protein inhibited transport by distinct mechanisms, but each process was dependent on Rab1. Mutant TDP-43 and mutant FUS both inhibited the incorporation of secretory protein cargo into COPII vesicles as they bud from the ER, and inhibited transport from ER to the ER-Golgi intermediate (ERGIC) compartment. TDP-43 was detected on the cytoplasmic face of the ER membrane, whereas FUS was present within the ER, suggesting that transport is inhibited from the cytoplasm by mutant TDP-43, and from the ER by mutant FUS. In contrast, mutant SOD1 destabilised microtubules and inhibited transport from the ERGIC compartment to Golgi, but not from ER to ERGIC. Rab1 performs multiple roles in ER-Golgi transport, and over-expression of Rab1 restored ER-Golgi transport, and prevented ER stress, mSOD1 inclusion formation and induction of apoptosis, in cells expressing mutant TDP-43, FUS or SOD1. Rab1 also co-localised extensively with mutant TDP-43, FUS and SOD1 in neuronal cells, and Rab1 formed inclusions in motor neurons of spinal cords from sporadic ALS patients, which were positive for ubiquitinated TDP-43, implying that Rab1 is misfolded and dysfunctional in sporadic disease. These results demonstrate that ALS-mutant forms of TDP-43, FUS, and SOD1 all perturb protein transport in the early secretory pathway, between ER and Golgi compartments. These data also imply that restoring Rab1-mediated ER-Golgi transport is a novel therapeutic target in ALS. PMID:26298469

  12. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers: A Case Study of Regional Entrepreneurship in Finland

    OpenAIRE

    Teijo Palander; Mika Vainikka; Antti Yletyinen

    2012-01-01

    The objectives of this study were to investigate how to increase co-operation in the regional entrepreneurship approach of wood transportation and facilitate the ongoing outsourcing of wood-procurement responsibilities in the Finnish forest industry. We examined co-operation between transportation entrepreneurs (suppliers) and between suppliers and the forest industry (customers). A questionnaire was sent to wood transportation entrepreneurs working in the wood-procurement network of the cust...

  13. Sediment Transport

    DEFF Research Database (Denmark)

    Liu, Zhou

    1999-01-01

    Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sedi...

  14. Neutron transport

    International Nuclear Information System (INIS)

    This bibliographical note presents a reference book which addresses the study of neutron transport in matter, the study of conditions for a chain reaction and the study of modifications of matter composition due to nuclear reactions. This book presents the main nuclear data, their measurement, assessment and processing, and the spallation. It proposes an overview of methods applied for the study of neutron transport: basic equations and their derived forms, deterministic methods and Monte Carlo method of resolution of the Boltzmann equation, methods of resolution of generalized Bateman equations, methods of time resolution of space kinetics coupled equations. It presents the main calculation codes, discusses the qualification and experimental aspects, and gives an overview of neutron transport applications: neutron transport calculation of reactors, neutron transport coupled with other disciplines, physics of fuel cycle, criticality

  15. Regulation mechanism of rosiglitazone on the oligopeptide transporter (PepT1 in septic rats after cecal ligation and puncture

    Directory of Open Access Journals (Sweden)

    Li-ping LIU

    2013-07-01

    Full Text Available Objective?To explore the regulation effect and its mechanism of rosiglitazone on the oligopeptide transporter (PepT1 expression in rats after cecal ligation and puncture (CLP. Methods?Forty-eight SD rats were randomly divided into 6 groups (8 each: CLP group (C group, sham operation group (S group, CLP+rosiglitazone group (R group, CLP+rosiglitazone+insulin group (RI group, CLP+insulin group (CI group, and normal control group (N group. Rats in C, S and CI groups received 0.9% NaCl solution by intragastric administration 30min before CLP or sham operation, while in R and RI group, rats received rosiglitazone instead. Rats in RI and CI group received insulin through femoral vein 150min after CLP. Glucose was measured at 30min preoperatively and every 30min postoperatively (30, 60, 90, 120, 150min. Arterial blood and proximal jejunum were harvested at 150min. Plasma D-lactate was determined by ultraviolet spectrophotometry. Serum IL-6, TNF-? and IL-10 were determined by ELISA. Pept1 expression was detected by Western blotting. Results?When rosiglitazone was given preoperatively, the respiratory rate, neutrophil count, glucose concentration, and the levels of TNF-?, IL-6, IL-10 and plasma D-lactate all decreased significantly after CLP (P<0.05 or P<0.01. Rosiglitazone-pretreatment increased PepT1 expression in both baseline and insulin-induced conditions (P<0.05. Conclusion?Rosiglitazone may increase the PepT1 expression in jejunal mucosa by reducing inflammatory cytokines in sepsis.

  16. Advection and dispersion heat transport mechanisms in the quantification of shallow geothermal resources and associated environmental impacts.

    Science.gov (United States)

    Alcaraz, Mar; García-Gil, Alejandro; Vázquez-Suñé, Enric; Velasco, Violeta

    2016-02-01

    Borehole Heat Exchangers (BHEs) are increasingly being used to exploit shallow geothermal energy. This paper presents a new methodology to provide a response to the need for a regional quantification of the geothermal potential that can be extracted by BHEs and the associated environmental impacts. A set of analytical solutions facilitates accurate calculation of the heat exchange of BHEs with the ground and its environmental impacts. For the first time, advection and dispersion heat transport mechanisms and the temporal evolution from the start of operation of the BHE are taken into account in the regional estimation of shallow geothermal resources. This methodology is integrated in a GIS environment, which facilitates the management of input and output data at a regional scale. An example of the methodology's application is presented for Barcelona, in Spain. As a result of the application, it is possible to show the strengths and improvements of this methodology in the development of potential maps of low temperature geothermal energy as well as maps of environmental impacts. The minimum and maximum energy potential values for the study site are 50 and 1800W/m(2) for a drilled depth of 100m, proportionally to Darcy velocity. Regarding to thermal impacts, the higher the groundwater velocity and the energy potential, the higher the size of the thermal plume after 6months of exploitation, whose length ranges from 10 to 27m long. A sensitivity analysis was carried out in the calculation of heat exchange rate and its impacts for different scenarios and for a wide range of Darcy velocities. The results of this analysis lead to the conclusion that the consideration of dispersion effects and temporal evolution of the exploitation prevent significant differences up to a factor 2.5 in the heat exchange rate accuracy and up to several orders of magnitude in the impacts generated. PMID:26605833

  17. (abstract) Fundamental Mechanisms of Electrode Kinetics and Alkali Metal Atom Transport at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    Science.gov (United States)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kisor, A.; Kikkert, S. K.

    1993-01-01

    The mechanisms of electrode kinetics and mass transport of alkali metal oxidation and alkali metal cation reduction at the solid electrolyte/porous electrode boundary as well as alkali metal transport through porous metal electrodes has important applications in optimizing device performance in alkali metal thermal to electric converter (AMTEC) cells which are high temperature, high current density electrochemical cells. Basic studies of these processes also affords the opportunity to investigate a very basic electrochemical reaction over a wide range of conditions; and a variety of mass transport modes at high temperatures via electrochemical techniques. The temperature range of these investigations covers 700K to 1240K; the alkali metal vapor pressures range from about 10(sup -2) to 10(sup 2) Pa; and electrodes studied have included Mo, W, Mo/Na(sub 2)MoO(sub 4), W/Na(sub 2)WO(sub 4), WPt(sub x), and WRh(sub x) (1.0 electrodes.

  18. Impact of the base doping concentration on the transport mechanisms in n-type a-SiGe:H/p-type c-Silicon Heterojunctions

    Scientific Electronic Library Online (English)

    P., Rosales-Quintero; M., Moreno-Moreno; A., Torres-Jacome; F.J. De la, Hidalga Wade; J., Molina-Reyes; W., Calleja-Arriaga; C., Zuñiga-Islas.

    2011-04-01

    Full Text Available Heterouniones de a-SiGe:H tipo-n sobre silicio cristalino tipo-p con cuatro diferentes concentraciones pico en la base (l x lO15, 7 x lO16, 7 x l0(17) y 5 x lO18 cm-3) fueron fabricadas y caracterizadas. Los mecanismos de transporte se determinaron por medio de sus curvas características de corrient [...] e vs voltaje en función de la temperatura. El análisis de los resultados muestra que a bajos voltajes de polarización directa (V 0.45V) el efecto de corriente limitada por carga espacial (SCLC) es el mecanismo de transporte dominante en todos los dispositivos caracterizados. El incremento en la concentración de dopantes en la base, además, causa un aumento en la corriente inversa. Abstract in english The charge transport mechanisms occurring in n-type a-SiGe:H on p-type c-Si heteroj unctions were determined by analyzing the temperature dependence of the current-voltage characteristics in structures with four different peak base doping concentrations (N B = 1 x 10(15), 7 x 10(16), 7 x l0(17) and [...] 5 x lO18 cm-3). From the experimental results, we observed that at low forward bias (V 0.45V), the space charge limited current effect became the dominant transport mechanism for all the measured devices. Under reverse bias the transport mechanisms depends on the peak base doping, going from carrier generation inside the space charge region for the lowest doping, to hopping and thermionic field emission as the base doping concentration is increased.

  19. Intestinal absorption mechanisms of MTBH, a novel hesperetin derivative, in Caco-2 cells, and potential involvement of monocarboxylate transporter 1 and multidrug resistance protein 2.

    Science.gov (United States)

    Shen, Chenlin; Chen, Ruonan; Qian, Zhengyue; Meng, Xiaoming; Hu, Tingting; Li, Yangyang; Chen, Zhaolin; Huang, Cheng; Hu, Chaojie; Li, Jun

    2015-10-12

    Hesperetin, the aglycone of hesperidin, occurs naturally in citrus fruits. It exerts extensive pharmacological activities. However, hesperetin's poor solubility and low bioavailability limit its wide application. In order to overcome these limitations, recently a series of novel hesperitin derivatives containing Mannich base moieties were synthesized and the anti-inflammatory activity was evaluated, among which MTBH (8-methylene-tert-butylamine-3',5,7-trihydroxy-4'-methoxyflavanone) showed a significantly improved water solubility, and promising anti-inflammatory activity in vitro and in vivo compared with hesperitin. Thus, the aim of this study was to investigate the permeability and transport mechanisms of MTBH, using Caco-2 cell monolayer. MTBH was effectively absorbed by Caco-2 cells in a concentration-dependent manner in both directions at 7.5-480 ?M. Moreover, MTBH showed pH dependent and TEER values independent transport in both directions. Transport of MTBH was obviously decreased in the presence of sodium azide (an ATP inhibitor) or CCCP (a proton-ionophore). MTBH transport was markedly reduced by MCT inhibitors quercetin or phloretin, and the substrate analogs l-lactate or benzoic acid. We verified MCT1, MCT3, MCT4, MCT5, and MCT6 were expressed in Caco-2 cells by western blot. Silence MCT1 with siRNA resulted in significant inhibition of MTBH uptake. The verapamil, a P-gp inhibitor, and Ko143, a BCRP inhibitor, had no effect on the transport of MTBH. However, MK-571 or probenecid, MRP2 inhibitors, led to an apparently decrease in the efflux of MTBH. In summary, MTBH was absorbed by transcellular passive diffusion and a pH dependent mechanism mediated by MCT1. MRP2 but P-gp or BCRP may be involved in the transport of MTBH. PMID:26231439

  20. Inhibition Mechanism of the Intracellular Transporter Ca2+-Pump from Sarco-Endoplasmic Reticulum by the Antitumor Agent Dimethyl-Celecoxib

    OpenAIRE

    Coca, Ramón; Soler, Fernando; Cortés-Castell, Ernesto; Gil-Guillén, Vicente; Fernández-Belda, Francisco

    2014-01-01

    Dimethyl-celecoxib is a celecoxib analog that lacks the capacity as cyclo-oxygenase-2 inhibitor and therefore the life-threatening effects but retains the antineoplastic properties. The action mechanism at the molecular level is unclear. Our in vitro assays using a sarcoplasmic reticulum preparation from rabbit skeletal muscle demonstrate that dimethyl-celecoxib inhibits Ca2+-ATPase activity and ATP-dependent Ca2+ transport in a concentration-dependent manner. Celecoxib was a more potent inhi...

  1. Review on mechanisms and continuum models of multi-phase transport phenomena in porous structures of non-aqueous Li-Air batteries

    Science.gov (United States)

    Yuan, Jinliang; Yu, Jong-Sung; Sundén, Bengt

    2015-03-01

    During recent years intensive research activities involving both experimental and modeling approaches have appeared for different aspects of Lithium-air (Li-air) battery. Multi-phase transport phenomena including dissolved oxygen and lithium ions (Li+) in the liquid electrolyte, as well as electrons in the solid materials, are strongly coupled with the porous structures and various reactions, particularly the solid product grown in the porous cathode during battery discharge. Understanding the mechanisms of transport phenomena and accurate evaluation of effective transport properties are significant for improving the battery capacities and design, especially at high rate conditions. In this paper, the transport governing equations commonly used for macroscopic continuum models at porous-average level are outlined and highlighted, with a purpose to provide a general overview of the validity and the limitation of these approaches. The most often used models in the open literature are reviewed and discussed focusing on the effective properties involving tortuosity factors, solid product morphologies, as well as effects on the void space clogging, surface area reduction and passivation. Comments and suggestions are also provided for better understanding of multi-phase transport phenomena and implementation of the detailed models for solid product generation and morphology growth in Li-air battery cathodes.

  2. Multiple drug resistance associated with function of ABC-transporters in diabetes mellitus: molecular mechanism and clinical relevance.

    Science.gov (United States)

    Koehn, J; Fountoulakis, M; Krapfenbauer, K

    2008-06-01

    ATP-binding cassette (ABC) transporters are involved in a variety of physiological processes such as lipid metabolism, ion homeostasis and immune functions. A large number of these proteins have been causatively linked to rare and common human genetic diseases including familial high-density lipoprotein deficiency, retinopathies, cystic fibrosis, diabetes and cardiomyopathies. Furthermore, genetic variations in ABC transporter genes and deregulated expression patterns significantly contribute to drug resistance in human cancer and pancreatic beta cells and alter the pharmacokinetic properties of a variety of drugs. Up-to-date 15 ABC transporters have been identified in human pancreatic beta cells, however only a few of them are identified to date as proteins/genes associated with multidrug resistance (MDR) in diabetes mellitus. Prominent members include the multidrug resistance protein 1 (MRP1/ABCC1), sulfonylurea receptor 1 (SUR1/ABCC8), the multi drug transporter TAP2 and member of the ATP-binding cassette transporter subfamily A (ABCA1). ABCC8 is a subunit of the pancreatic beta-cell K(ATP) channel and plays a key role in the regulation of glucose-induced insulin secretion. Although the physiological role of these transporters to MDR is not yet fully understood, they play an important role in the blood-membrane barrier in pancreatic beta cells. The aim of this article is to provide an overview and to present few examples of drug treatment in MDR in diabetes mellitus associated with function of ABC-transporters. PMID:18537706

  3. Análise comparativa entre os mecanismos de trauma, as lesões e o perfil de gravidade das vítimas, em Catanduva - SP / Mechanisms of trauma, main injuries and severity of patients’ conditions in Catanduva - SP

    Scientific Electronic Library Online (English)

    Sandra Elisa Adami, Batista; Juliana Govoni, Baccani; Raquel Amarante de Paula e, Silva; Kamila de Paula Ferlin, Gualda; Raul José de Andrade, Vianna Jr..

    2006-02-01

    Full Text Available OBJETIVO: Realizar uma análise comparativa entre os principais mecanismos de trauma, a gravidade das vítimas e os principais ferimentos que proporcionaram. MÉTODO: Estudo randomizado de 1486 fichas de vítimas traumatizadas atendidas pela Unidade de Resgate do Corpo de Bombeiros em Catanduva - SP, no [...] período de janeiro/1997 a dezembro/2003. Foi realizada uma avaliação a partir dos itens ferimentos, Revised Trauma Score e mecanismos de trauma, cujas variáveis foram expressas em porcentagens e correlacionadas pelo Teste X². RESULTADOS: Houve predomínio de acidentes motociclísticos com 42,2% dos traumas. As regiões corpóreas mais acometidas foram os membros inferiores/cintura pélvica (32,2%). Os ferimentos superficiais acometeram 88% das vítimas. Para todos os eventos, prevaleceram vítimas com RTS=6 excetuando-se os acidentes envolvendo veículos pesados em que 25% das vítimas obtiveram RTS Abstract in english BACKGROUND: To compare main trauma mechanisms, main injuries and severity of patients’ conditions. METHODS: A retrospective study of 1486 records of trauma patients treated at the Firefighters’ Rescue Unit in Catanduva, Sao Paulo, from January 1997 to December 2003. Assessment was based on the follo [...] wing criteria: injuries, Revised Trauma Score, and trauma mechanisms. The variables were expressed in percentages and evaluated by X² Test. RESULTS: The most frequent accidents were motorcycle related (42% of the total). The most affected segments were the lower limbs and pelvis (32%). 88% of the patients had superficial injuries. Most patients had RTS6 for all types of accidents except for those related to large truck, in which 25% of the victims had RTS

  4. Mechanisms controlling surface ozone over East Asia: a multiscale study coupling regional and global chemical transport models

    Science.gov (United States)

    Lin, M.; Holloway, T.; Oki, T.; Streets, D. G.; Richter, A.

    2008-12-01

    Mechanisms controlling surface ozone (O3) over East Asia are examined using the regional Community Multiscale Air Quality (CMAQ) model at two horizontal scales: 81 km and 27 km. Through sensitivity studies and comparison with recently available satellite data and surface measurements in China and Japan, we find that the O3 budget over East Asia shows complex interactions among photochemical production, regional transport, meteorological conditions, burning of agricultural residues, and global inflows. For example, wintertime surface O3 over northern domain is sensitive to boundary conditions derived from the MOZART (Model for Ozone and Related Tracers) global model, whereas summertime O3 budget is controlled by the competitive processes between photochemical production and monsoonal intrusion of low-O3 marine air masses from tropical Pacific. We find that simulated surface O3 for 2001 does not exhibit the same sharp drop in July and August concentrations that is observed at two mountaintop sites (Tai and Hua) for 2004 and Beijing for 1995-2005. CMAQ sensitivity tests with two widely used photochemical schemes demonstrate that over the industrial areas in East Asia north of 30° N, SAPRC99 produces higher values of mean summertime O3 than CBIV, amounting to a difference of 10 ppb. In addition, analysis of NCEP winds and geopotential heights suggests that southwesterly monsoonal intrusion in central east China is weakened in August 2001 as compared with the climatologically mean for 1980-2005. Further examination of the O3 diurnal cycle at nine Japanese sites shows that boundary layer evolution has an important effect on the vertical mixing of ground-level O3, and error in near surface meteorology might contribute to overprediction of nighttime O3 in urban and rural areas. In conclusion, the uncertainties in simulating cloud activities and convection mixing, Asian monsoon circulation, photochemical production, and nighttime cooling explain why CMAQ with 81 km horizontal scale overpredicts the observed surface O3 in July and August over central east China and central Japan by 5-15 ppb (CBIV) and 15-25 ppb (SAPRC99). The results suggest clear benefits in evaluating atmospheric chemistry over Asia with high resolution regional model.

  5. Mechanisms controlling surface ozone over East Asia: a multiscale study coupling regional and global chemical transport models

    Directory of Open Access Journals (Sweden)

    M. Lin

    2008-12-01

    Full Text Available Mechanisms controlling surface ozone (O3 over East Asia are examined using the regional Community Multiscale Air Quality (CMAQ model at two horizontal scales: 81 km and 27 km. Through sensitivity studies and comparison with recently available satellite data and surface measurements in China and Japan, we find that the O3 budget over East Asia shows complex interactions among photochemical production, regional transport, meteorological conditions, burning of agricultural residues, and global inflows. For example, wintertime surface O3 over northern domain is sensitive to boundary conditions derived from the MOZART (Model for Ozone and Related Tracers global model, whereas summertime O3 budget is controlled by the competitive processes between photochemical production and monsoonal intrusion of low-O3 marine air masses from tropical Pacific. We find that simulated surface O3 for 2001 does not exhibit the same sharp drop in July and August concentrations that is observed at two mountaintop sites (Tai and Hua for 2004 and Beijing for 1995–2005. CMAQ sensitivity tests with two widely used photochemical schemes demonstrate that over the industrial areas in East Asia north of 30° N, SAPRC99 produces higher values of mean summertime O3 than CBIV, amounting to a difference of 10 ppb. In addition, analysis of NCEP winds and geopotential heights suggests that southwesterly monsoonal intrusion in central east China is weakened in August 2001 as compared with the climatologically mean for 1980–2005. Further examination of the O3 diurnal cycle at nine Japanese sites shows that boundary layer evolution has an important effect on the vertical mixing of ground-level O3, and error in near surface meteorology might contribute to overprediction of nighttime O3 in urban and rural areas. In conclusion, the uncertainties in simulating cloud activities and convection mixing, Asian monsoon circulation, photochemical production, and nighttime cooling explain why CMAQ with 81 km horizontal scale overpredicts the observed surface O3 in July and August over central east China and central Japan by 5–15 ppb (CBIV and 15–25 ppb (SAPRC99. The results suggest clear benefits in evaluating atmospheric chemistry over Asia with high resolution regional model.

  6. Quantum transport and electroweak baryogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Konstandin, Thomas

    2013-02-15

    We review the mechanism of electroweak baryogenesis. The main focus of the review lies on the development of quantum transport equations from first principles in the Kadanoff-Baym framework. We emphasize the importance of the semi-classical force that leads to reliable predictions in most cases. Besides, we discuss the status of electroweak baryogenesis in the light of recent electric dipole moment probes and collider experiments in a variety of models.

  7. Cement reactivity in CO2 saturated brines: use of a reactive transport code to highlight key degradation mechanisms

    International Nuclear Information System (INIS)

    A modular reactive transport code is proposed to analyze the reactivity of cement in CO2 saturated brine. The coupling of the transport module and the geochemical module within DynaflowTM is derived. Both modules are coupled in a sequential iterative approach to accurately model: (1) mineral dissolution/precipitation and (2) porosity dependent transport properties. Results of the model reproduce qualitatively the dissolution of cement hydrates (C-H, C-S-H, AFm, AFt) and intermediate products (CaCO3) into the brine. Slight discrepancies between modeling and experimental results were found concerning the dynamics of the mineral zoning. Results suggest that the power law relationship to model effective transport properties from porosity values is not accurate for very reactive case. (authors)

  8. Mechanisms of calcium transport in small intestine. Overall review of the contract, September 1, 1972--March 1, 1976

    Energy Technology Data Exchange (ETDEWEB)

    DeLuca, H.F.

    1976-01-01

    Progress is reported in the following areas of research: role of high molecular weight protein in calcium transport in vitamin D deficient chicks; subcellular localization of 1,25-(OH)/sub 2/D/sub 3/; receptor proteins for 1,25-(OH)/sub 2/D/sub 3/; effects of high calcium diet, strontium diet, EHDP, and parathyroidectomy on intestinal calcium transport in chicks; effects of analogs of 1,25-(OH)/sub 2/D/sub 3/ on intestinal calcium transport; discrimination by chicks against vitamin D/sub 2/ compounds by metabolism; effects of extract of Solanum malacoxylan on intestinal calcium absorption in nephrectomized rats; and role of vitamin D in phosphate transport reactions in the intestine. (HLW)

  9. The mechanism of ammonia transport based on the crystal structure of AmtB of Escherichia coli

    OpenAIRE

    Zheng, Lei; Kostrewa, Dirk; Bernèche, Simon; Winkler, Fritz K; Li, Xiao-dan

    2004-01-01

    Ammonium is one of the most important nitrogen sources for bacteria, fungi, and plants, but it is toxic to animals. The ammonium transport proteins (methylamine permeases/ammonium transporters/rhesus) are present in all domains of life; however, functional studies with members of this family have yielded controversial results with respect to the chemical identity (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} ...

  10. The role of multixenobiotic transporters in predatory marine molluscs as counter-defense mechanisms against dietary allelochemicals.

    Science.gov (United States)

    Whalen, Kristen E; Sotka, Erik E; Goldstone, Jared V; Hahn, Mark E

    2010-09-01

    Multixenobiotic transporters have been extensively studied for their ability to modulate the disposition and toxicity of pharmacological agents, yet their influence in regulating the levels of dietary toxins within marine consumers has only recently been explored. This study presents functional and molecular evidence for multixenobiotic transporter-mediated efflux activity and expression in the generalist gastropod Cyphoma gibbosum, and the specialist nudibranch Tritonia hamnerorum, obligate predators of chemically defended gorgonian corals. Immunochemical analysis revealed that proteins with homology to permeability glycoprotein (P-gp) were highly expressed in T. hamnerorum whole animal homogenates and localized to the apical tips of the gut epithelium, a location consistent with a role in protection against ingested prey toxins. In vivo dye assays with specific inhibitors of efflux transporters demonstrated the activity of P-gp and multidrug resistance-associated protein (MRP) families of ABC transporters in T. hamnerorum. In addition, we identified eight partial cDNA sequences encoding two ABCB and two ABCC proteins from each molluscan species. Digestive gland transcripts of C. gibbosum MRP-1, which have homology to vertebrate glutathione-conjugate transporters, were constitutively expressed regardless of gorgonian diet. This constitutive expression may reflect the ubiquitous presence of high affinity substrates for C. gibbosum glutathione transferases in gorgonian tissues likely necessitating export by MRPs. Our results suggest that differences in multixenobiotic transporter expression patterns and activity in molluscan predators may stem from the divergent foraging strategies of each consumer. PMID:20546934

  11. 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

    2015-01-01

    In the field of energy storage devices the pursuit for cheap, high energy density, reliable secondary batteries is at the top of the agenda. The Li-O2battery is one of the possible technologies that, in theory, should be able to close the gap, which exists between the present state-of-the-art Li-ion technologies and the demand placed on batteries by technologies such as electrical vehicles [1]. However, the Li-O2 battery still suffers greatly from high overpotentials during oxygen reduction and evolution reactions (discharge and charge, respectively), poor rechargeability, and decomposition of salts and 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 product lithium peroxide, Li2O2, using outer-sphere redox shuttles: cobaltocene, ferrocene, and decamethylferrocene. The change in heterogeneous electron transfer exchange rate as a function of the potential and the Li2O2 layer thickness (~state of charge) was determined using electrochemical impedance spectroscopy. The attenuation of the electron transfer exchange rate with film thickness is dependent on the probing potential, indicating that hole tunneling is the dominant process for charge transfer through Li2O2supporting previous work by Luntz et al. [4]. Additionally, this work includes the determination of diffusion coefficients and concentrations of the redox shuttles and the superoxide ion, in a 1,2-dimethoxyethane based electrolyte. References [1] S. A. Freunberger, P. G. Bruce, L. J. Hardwick et J.-M. Tarascon, «Li-O2 and Li-S batteries with high energy storage,» Nature Materials, vol. 11, pp. 19-29, 2012. [2] B. D. McCloskey, A. Valery, A. C. Luntz, S. R. Gowda, G. M. Wallraff, J. M. Garcia, T. Mori et L. E. Krupp, «Combining Accurate O2 and Li2O2 Assays to Separate Discharge and Charge stability Limitations in Nonaqueous Li-O2 Batteries,» J. Phys. Chem. Lett., vol. 4, pp. 2989-2993, 2013. [3] R. Younesi, M. Hahlin, F. Björefors, P. Johansson et K. Edström, «Li-O2 Battery Degradation by Lithium Peroxide (Li2O2): A Model Study,» Chem. Mater., vol. 25, pp. 77-84, 2013. [4] A. C. Luntz, V. Viswanathan, J. Voss, J. B. Varley, J. K. Nørskov, R. Scheffler and A. Speidel, "Tunneling and Polaron Charge Transport through Li2O2 in Li-O2 Batteries," J. Phys. Chem. Lett., vol. 4, pp. 3494-3499, 2013.

  12. The Fermilab Main Injector

    International Nuclear Information System (INIS)

    The Fermilab Main Injector is a new 150 GeV proton synchrotron, designed to replace the Main Ring and improve the high energy physics potential of Fermilab. The status of the Fermilab accelerator complex upgrade will be discussed

  13. Structural, mechanical and magnetic properties studies on high-energy Kr-ion irradiated Fe{sub 3}O{sub 4} material (main corrosion layer of Fe-based alloys)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jianrong, E-mail: sunjr@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Zhiguang; Zhang, Hongpeng; Song, Peng; Chang, Hailong; Cui, Minghuan; Pang, Lilong; Zhu, Yabin [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Fashen [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2014-12-15

    The Fe-based (T91 and RAFM) alloys are considered as the promising candidate structural materials for DEMO and the first fusion power plant, and these two kinds of steels suffered more serious corrosion attack at 450 °C in liquid PbBi metal. So in order to further clarify the applicability of Fe-based structural materials in nuclear facilities, we should study not only the alloys itself but also its corrosion layers; and in order to simplify the discussion and clarify the irradiation effects of the different corrosion layer, we abstract the Fe{sub 3}O{sub 4} (main corrosion layer of Fe-based alloys) to study the structural, micro-mechanical and magnetic properties under 2.03 GeV Kr-ion irradiation. The initial crystallographic structure of the Fe{sub 3}O{sub 4} remains unaffected after irradiation at low damage levels, but as the Kr-ion fluence increases and the defects accumulate, the macroscopic magnetic properties (M{sub s}, H{sub c}, etc.) and micro-mechanical properties (nano-hardness and Young’s modulus) are sensitive to high-energy Kr-ion irradiation and exhibit excruciating uniform changing regularities with varying fluences (firstly increases, then decreases). And these magnetism, hardening and softening phenomena can be interpreted very well by the effects related to the stress and defects (the production, accumulation and free) induced by high-energy ions irradiation.

  14. Análise comparativa entre os mecanismos de trauma, as lesões e o perfil de gravidade das vítimas, em Catanduva - SP Mechanisms of trauma, main injuries and severity of patients’ conditions in Catanduva - SP

    Directory of Open Access Journals (Sweden)

    Sandra Elisa Adami Batista

    2006-02-01

    Full Text Available OBJETIVO: Realizar uma análise comparativa entre os principais mecanismos de trauma, a gravidade das vítimas e os principais ferimentos que proporcionaram. MÉTODO: Estudo randomizado de 1486 fichas de vítimas traumatizadas atendidas pela Unidade de Resgate do Corpo de Bombeiros em Catanduva - SP, no período de janeiro/1997 a dezembro/2003. Foi realizada uma avaliação a partir dos itens ferimentos, Revised Trauma Score e mecanismos de trauma, cujas variáveis foram expressas em porcentagens e correlacionadas pelo Teste X². RESULTADOS: Houve predomínio de acidentes motociclísticos com 42,2% dos traumas. As regiões corpóreas mais acometidas foram os membros inferiores/cintura pélvica (32,2%. Os ferimentos superficiais acometeram 88% das vítimas. Para todos os eventos, prevaleceram vítimas com RTS=6 excetuando-se os acidentes envolvendo veículos pesados em que 25% das vítimas obtiveram RTSBACKGROUND: To compare main trauma mechanisms, main injuries and severity of patients’ conditions. METHODS: A retrospective study of 1486 records of trauma patients treated at the Firefighters’ Rescue Unit in Catanduva, Sao Paulo, from January 1997 to December 2003. Assessment was based on the following criteria: injuries, Revised Trauma Score, and trauma mechanisms. The variables were expressed in percentages and evaluated by X² Test. RESULTS: The most frequent accidents were motorcycle related (42% of the total. The most affected segments were the lower limbs and pelvis (32%. 88% of the patients had superficial injuries. Most patients had RTS6 for all types of accidents except for those related to large truck, in which 25% of the victims had RTS<2. If we ignore motor vehicle accidents, 63.4% were falls. There was association between trauma mechanisms and injured segment of the body (p <0.01. The lower limbs/pelvis were the most affected body parts in accidents involving people hit by cars and motorcycle accidents. The head/neck were injured in agressions, falls, and accidents involving large trucks and cars. Cyclists had similar head/neck and lower patients limb/pelvis injuries. CONCLUSION: The majority of trauma patients in Catanduva were victims of motorcycle accidents. The part of the body most frequently injured was the the lower limbs/pelvis. Most patients had superficial injuries characterized as mild trauma.

  15. CIEMAT results in the frame of the european project Mechanisms governing the behaviour and transport of transuranics (analogues) and other radionuclides in marine ecosystems

    International Nuclear Information System (INIS)

    This report summarises the objectives and more relevant conclusions obtained by CIEMAT in the frame of the project Mechanisms governing the behaviour and transport of transuranics (analogues) and other radionuclides in marine ecosystems. The overall objective of this project was to identify the basic mechanisms and define the key parameters governing the physico-chemical speciation, vertical and horizontal mobility, biological magnification, incorporation to seabed sediments and ultimate fate of transuranium and other long-lived radionuclides in the marine environment, with a view to providing high-quality data of a universal character for use in the development and validation of predictive models based on fundamental mechanisms rather than the simpler box-model approach. This research was carried out in different European marine ecosystems: those directly affected by controlled releases from Nuclear Industries and/or accidents and those characterized by being preferent radionuclides accumulation sites (submarine canyons, estuaries, etc.). (Author)

  16. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  17. Identification of a transport mechanism for NH4+ in the symbiosome membrane of pea root nodules

    DEFF Research Database (Denmark)

    Mouritzen, P.; Rosendahl, L.

    1997-01-01

    Symbiosome membrane vesicles, facing bacteroid-side-out, were purified from pea (Pisum sativum L.) root nodules and used to study NH4+ transport across the membrane by recording vesicle uptake of the NH4+ analog [C-14]methylamine (MA). Membrane potentials (Delta psi) were imposed on the vesicles using K+ concentration gradients and valinomycin, and the size of the imposed Delta psi was determined by measuring vesicle uptake of [C-14]tetraphenylphosphonium. Vesicle uptake of MA was driven by a negative Delta psi and was stimulated by a low extravesicular pH. Protonophore-induced collapse of the pH gradient indicated that uptake of MA was not related to the presence of a pH gradient. The MA-uptake mechanism appeared to have a large capacity for transport, and saturation was not observed at MA concentrations in the range of 25 mu M to 150 mM. MA uptake could be inhibited by NH4+, which indicates that NH4+ and MA compete for the same uptake mechanism. The observed fluxes suggest that voltage-driven channels are operating in the wsymbiosome membrane and that these are capable of transporting NH4+ at high rates from the bacteroid side of the membrane to the plant cytosol. The pH of the symbiosome space is likely to be involved in regulation of the flux.

  18. Molecular mechanisms of the epithelial transport of toxic metal ions. Final report, September 1, 1975-December 31, 1985

    Energy Technology Data Exchange (ETDEWEB)

    Wasserman, R.H.; Fullmer, C.S.

    1986-01-01

    Studies were undertaken to examine the effects of various factors on the intestinal absorption of cadmium, zinc, arsenate and lead as well as the toxic effects of cadmium and lead on the intestinal transport of calcium. Intestinal cadmium absorption was influenced by many of the same factors which influence calcium transport, although there was no direct evidence for a common transport pathway. Cadmium inhibited the intestinal absorption of calcium, primarily at the intestinal level, since no effect on the cholecalciferol endocrine system was observed. Many similarities and differences were documented for intestinal lead and calcium transport, suggesting that these two cations share some of the same transport components. The effect of dietary lead was far more severe under conditions of dietary calcium restriction, effectively eliminating the adaptation response via the cholecalciferol endocrine system. This effect was attributed partially to lead inhibition of renal production of the active hormone, although direct inhibition, at the intestinal level, was also suggested. Several members of the troponin C family of calcium-binding proteins were shown to bind lead in preference to calcium, suggesting that many of the toxic manifestations of lead may be related to perturbation of calcium-mediated cellular processes. 110 refs.

  19. Molecular mechanisms of the epithelial transport of toxic metal ions. Final report, September 1, 1975-December 31, 1985

    International Nuclear Information System (INIS)

    Studies were undertaken to examine the effects of various factors on the intestinal absorption of cadmium, zinc, arsenate and lead as well as the toxic effects of cadmium and lead on the intestinal transport of calcium. Intestinal cadmium absorption was influenced by many of the same factors which influence calcium transport, although there was no direct evidence for a common transport pathway. Cadmium inhibited the intestinal absorption of calcium, primarily at the intestinal level, since no effect on the cholecalciferol endocrine system was observed. Many similarities and differences were documented for intestinal lead and calcium transport, suggesting that these two cations share some of the same transport components. The effect of dietary lead was far more severe under conditions of dietary calcium restriction, effectively eliminating the adaptation response via the cholecalciferol endocrine system. This effect was attributed partially to lead inhibition of renal production of the active hormone, although direct inhibition, at the intestinal level, was also suggested. Several members of the troponin C family of calcium-binding proteins were shown to bind lead in preference to calcium, suggesting that many of the toxic manifestations of lead may be related to perturbation of calcium-mediated cellular processes. 110 refs

  20. Increased transvascular escape rate and lymph drainage of albumin in pigs during intravenous diuretic medication. Relations to treatment in man and transport mechanisms

    DEFF Research Database (Denmark)

    Henriksen, J H; Parving, H H

    1982-01-01

    Transvascular escape rate of albumin (TERalb, i.e. the fraction of intravascular mass of albumin (IVMalb) passing to (or during steady state returning from) the extravascular space per unit time) was determined from the initial disappearance rate of i.v. injected radioiodinated serum albumin in anaesthetized pigs during control conditions and during diuretic medication (furosemide i.v. 20 mg/15 min, total 160-200 mg). During diuretic medication TERalb (mean 17.1% IVMalb X h-1, range 11.5-21, n = 6) increased significantly above the control period (mean 12.3% IVMalb X h-1, range 9.5-16.5, P less than 0.05). Pressures in artery, right atrium, hepatic and portal veins did not change significantly from control to diuretic period. TERalb equals the lymphatic return rate of albumin provided the transport mechanisms are filtrative-convective (i.e. no local back transport). Additional measurements in five pigs with proteins of different molecular size confirmed a dominating filtrative-convective transport. The increased TERalb during diuretic medication is best explained by an increased lymph drainage, which may decrease interstitial fluid pressure and thereby increase the transmural capillary pressure difference being essential for a filtrative-convective transvascular albumin transport. Increased lymph drainage may contribute to the therapeutic effect of diuretic treatment in oedema and ascites.

  1. A critical review of cooperative agreement as a mechanism for state, tribal, and local government participation in DOE transportation programs

    International Nuclear Information System (INIS)

    This paper discusses the transportation program-related cooperative agreements held by the Department of Energy of Civilian Radioactive Waste Management (OCRWM) Transportation Branch, ORCWM headquarters, the Office of Environmental Restoration and Waste Management (EM) Transportation Management Program (TMP), and the Waste Isolation Pilot Plant (WIPP). The paper explores the reasons for instituting cooperative agreements, the roles of DOE staff and State, Tribal, and local government organization staff in establishing scopes of work and budget levels, participants' roles in executing the agreements, and the impact of the agreements on the policy-making process. Lessons learned about the factor that have contributed to the success of many agreements and difficulties in finalizing and carrying out other agreements are also reviewed

  2. Mechanisms of calcium transport in small intestine. Progress report, March 1, 1976--September 30, 1977. [Chickens, rats, lead

    Energy Technology Data Exchange (ETDEWEB)

    DeLuca, H.F.

    1977-01-01

    Progress is reported on the following research projects: subcellular location of 1,25-dihydroxyvitamin D/sub 3/(1,25-(OH)/sub 2/D/sub 3/) in intestine of chickens; studies on receptor proteins in intestine for 1,25-(OH)/sub 2/D3; studies on intestinal cytosol receptors in chickens and rats; control of intestinal calcium transport; effect of calcitonin on 25-OH-D/sub 3/-1-hydroxylase; isolation and identification of the active principle of Solonum glaucophyllum, the South American plant that causes metastatic calcification and death to grazing animals; and studies on lead transport in vitro and in vivo. (HLW)

  3. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers: A Case Study of Regional Entrepreneurship in Finland

    Directory of Open Access Journals (Sweden)

    Teijo Palander

    2012-06-01

    Full Text Available The objectives of this study were to investigate how to increase co-operation in the regional entrepreneurship approach of wood transportation and facilitate the ongoing outsourcing of wood-procurement responsibilities in the Finnish forest industry. We examined co-operation between transportation entrepreneurs (suppliers and between suppliers and the forest industry (customers. A questionnaire was sent to wood transportation entrepreneurs working in the wood-procurement network of the customers. The entrepreneurs felt that the most interesting form of consortium between suppliers, which would let them respond better to outsourcing, would be the formation of a joint venture responsible for sales and marketing of their services. Such a company would develop an overall contract with each customer, and then each shareholder in the joint venture would sign their own contracts with the venture to share the work. All transactions would be based on invoicing instead of the current salary-based approach. However, entrepreneurs did not believe that their profitability would increase by expanding their responsibilities in the current entrepreneurial environment. If the aim of co-operation is to outsource the wood transportation function, decision-makers in the Finnish forest industry should modify the current environment so that larger, more organized consortia of wood suppliers would become more profitable than they presently are in the regional entrepreneurship approach.

  4. Transport mechanism of reverse surface leakage current in AlGaN/GaN high-electron mobility transistor with SiN passivation

    Science.gov (United States)

    Zheng, Xue-Feng; Fan, Shuang; Chen, Yong-He; Kang, Di; Zhang, Jian-Kun; Wang, Chong; Mo, Jiang-Hui; Li, Liang; Ma, Xiao-Hua; Zhang, Jin-Cheng; Hao, Yue

    2015-02-01

    The transport mechanism of reverse surface leakage current in the AlGaN/GaN high-electron mobility transistor (HEMT) becomes one of the most important reliability issues with the downscaling of feature size. In this paper, the research results show that the reverse surface leakage current in AlGaN/GaN HEMT with SiN passivation increases with the enhancement of temperature in the range from 298 K to 423 K. Three possible transport mechanisms are proposed and examined to explain the generation of reverse surface leakage current. By comparing the experimental data with the numerical transport models, it is found that neither Fowler-Nordheim tunneling nor Frenkel-Poole emission can describe the transport of reverse surface leakage current. However, good agreement is found between the experimental data and the two-dimensional variable range hopping (2D-VRH) model. Therefore, it is concluded that the reverse surface leakage current is dominated by the electron hopping through the surface states at the barrier layer. Moreover, the activation energy of surface leakage current is extracted, which is around 0.083 eV. Finally, the SiN passivated HEMT with a high Al composition and a thin AlGaN barrier layer is also studied. It is observed that 2D-VRH still dominates the reverse surface leakage current and the activation energy is around 0.10 eV, which demonstrates that the alteration of the AlGaN barrier layer does not affect the transport mechanism of reverse surface leakage current in this paper. Project supported by the National Natural Science Foundation of China (Grant Nos. 61334002, 61106106, and 61474091), the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory, China (Grant No. ZHD201206), the New Experiment Development Funds for Xidian University, China (Grant No. SY1213), the 111 Project, China (Grant No. B12026), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, and the Fundamental Research Funds for the Central Universities, China (Grant No. K5051325002).

  5. Measurements of polluted air masses from Eurasia at a surface site in the Pacific Northwest: the importance of transport mechanisms on the chemical composition

    Science.gov (United States)

    Snow, J. A.; Jaffe, D. A.; Weiss, P. S.; Price, H. U.; Jaeglé, L.; McClintick, A.

    2002-12-01

    Springtime measurements of carbon monoxide (CO), ozone (O3), nonmethane hydrocarbons (NMHCs), and aerosols were collected at Cheeka Peak Observatory (CPO), located at 48.3 N and 124.6 W, during the Photochemical Ozone Budget of the Eastern North Pacific (PHOBEA-I and II) experiments, 1997-98 and 2001-02. The purpose of these experiments was to quantify the long-range transport (LRT) of pollutants from the Eurasian continent to the Pacific Northwest (PNW) United States and examine the impact on the photochemical O3 budget and local air quality in this region. During this study, 8 distinct LRT events were documented at CPO, when the transport of Eurasian industrial pollution, dust, or haze from Asian biomass burning was measured. These events were defined by enhanced CO (up to 190 ppbv), O3 (up to 60 ppbv), NMHCs, and aerosol scattering coefficients (reaching 40 Mm-}{1). However, aircraft measurements over CPO (0-6 km) during the spring of 2001 and 2002 indicate that LRT events were often observed at altitudes above 2 km. For example, several aircraft vertical profiles collected during this experiment measured elevated CO and O3 above 2 km due to LRT that did not correlate with enhanced measurements at CPO. In addition, not all LRT events contained elevated O3, possibly due to different sources or the result of loss due to HOx chemistry in the boundary layer, or precipitation and heterogeneous chemistry along the transport path. These observations are employed in our subsequent analysis of the transport mechanisms bringing Eurasian pollution to the CPO surface site and how these transport pathways influence the chemical composition of the air masses observed at CPO.

  6. Mechanisms of Air Pollution Transport in Urban Valleys as a Result of the Interplay Between the Temperature Inversion and the Urban Heat Island Effect

    Science.gov (United States)

    Rendón, A.; Wirth, V.; Salazar, J. F.; Palacio, C. A.; Brötz, B.

    2014-12-01

    Urban valleys can experience serious air pollution problems of concern for public health. The venting of pollution out of an urban valley is limited by the topography and can be further restricted by low-level temperature inversions and/or local circulations such as those induced by the Urban Heat Island (UHI) effect. The combined effects of a temperature inversion and a UHI on the dynamics of the atmospheric boundary layer and the associated mechanisms of air pollution transport in urban valleys were studied through idealized simulations performed with the EULAG model. Three different aspects were considered: the expansion of the urban area, variations in surface heating owing to topographic shading, and variations of the topography. The results show that different mechanisms of air pollution transport may arise in urban valleys as a result of the interplay between the temperature inversion, the slope flows, and the UHI. Three types of interrelated mechanisms of air pollution transport were identified. Type A describes the transport of pollutants by the slope winds, which can reduce pollution in the lower levels or reinforce the trapping of pollutants below the inversion layer depending on the UHI effect on weakening or reversing the upslope winds. Type B describes closed slope-flow circulations that are likely to occur below an inversion layer near the base of the sidewalls of valleys where an urban area is concentrated on the valley floor. These circulations can develop when upslope winds are detrained toward the center due to the inversion layer, or when the UHI forces downslope winds linked to ascending flows that are also restricted by the inversion layer. Pollutants can remain trapped within these circulation cells that have been termed smog traps. Type C describes a low-level UHI-induced circulation that tends to concentrate pollutants in the valley center and may cause the development of elevated polluted layers below the inversion layer. The persistence of these type of mechanisms could cause severe air pollution episodes in urban valleys. Despite the completely idealized framework adopted, this study provides evidence about a series of physical processes that are likely to occur in nature and agrees well with previous studies.

  7. Evaluate and characterize mechanisms controlling transport, fate, and effects of army smokes in the aerosol wind tunnel: Transport, transformations, fate, and terrestrial ecological effects of hexachloroethane obscurant smokes

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, D.A.; Ligotke, M.W.; Bolton, H. Jr.; Fellows, R.J.; Van Voris, P.; McVeety, B.D.; Li, Shu-mei W.; McFadden, K.M.

    1989-09-01

    The terrestrial transport, chemical fate, and ecological effects of hexachloroethane (HC) smoke were evaluated under controlled wind tunnel conditions. The primary objectives of this research program are to characterize and assess the impacts of smoke and obscurants on: (1) natural vegetation characteristic of US Army training sites in the United States; (2) physical and chemical properties of soils representative of these training sites; and (3) soil microbiological and invertebrate communities. Impacts and dose/responses were evaluated based on exposure scenarios, including exposure duration, exposure rate, and sequential cumulative dosing. Key to understanding the environmental impacts of HC smoke/obscurants is establishing the importance of environmental parameters such as relative humidity and wind speed on airborne aerosol characteristics and deposition to receptor surfaces. Direct and indirect biotic effects were evaluated using five plant species and two soil types. HC aerosols were generated in a controlled atmosphere wind tunnel by combustion of hexachloroethane mixtures prepared to simulate normal pot burn rates and conditions. The aerosol was characterized and used to expose plant, soil, and other test systems. Particle sizes of airborne HC ranged from 1.3 to 2.1 {mu}m mass median aerodynamic diameter (MMAD), and particle size was affected by relative humidity over a range of 20% to 85%. Air concentrations employed ranged from 130 to 680 mg/m{sup 3}, depending on exposure scenario. Chlorocarbon concentrations within smokes, deposition rates for plant and soil surfaces, and persistence were determined. The fate of principal inorganic species (Zn, Al, and Cl) in a range of soils was assessed.

  8. I-t, J-1/T and J-E characteristics for the understanding of the main mechanism of electric conduction and the determination of the glass transition temperature of parylene C thin films

    International Nuclear Information System (INIS)

    Measurements under both transient and steady-state conditions on parylene C (-H2C - C6H3Cl - CH2-)n, also called PPX C, were made for different electric fields ranging from 8.33 to 33.33 MV m-1. The transient current behaviour is hyperbolic in nature up to 125 °C. Above, the current is transient free and becomes constant reflecting the presence of the steady state. The decay rate of the transient current increases with increasing temperature and field. The transient current is attributed mainly to the dipolar relaxation due to the polarization of the C-Cl dipole. The J-1/T characteristic reflects the change in the conduction regime occurring at a critical temperature associated with the glass transition temperature of the materials. The J-E measurements show that hopping conduction is the possible mechanism below and above Tg of parylene C. The activation energy is determined to be 0.13 eV, independent of the electric fields below Tg and varies from 0.65 to 0.94 eV above Tg, indicating the presence of more than one type of trapping centres in parylene C. The ionic jump distance ‘a’ is estimated to be 5.60-6.68 Å below Tg and 8.36-26.58 Å above Tg. (paper)

  9. Mechanisms of Pathogen and Surrogate Transport in Porous Media: Concurrent Effects of Grain Characteristics, NOM and Ionic Strength

    Science.gov (United States)

    Emelko, M. B.; Stimson, J.; McLellan, N.; Tufenkji, N.

    2009-05-01

    It is widely accepted that riverbank filtration (RBF) can provide substantial reductions in the concentrations of both microbial and chemical contaminants while providing more consistent water quality to subsequent treatment processes. Factors such as experimental scale, subsurface heterogeneity, and variable flow paths and fluxes have made it difficult to relate laboratory outcomes to field performance. Field studies have been plagued with inadequate consideration of ground water flow, reliance on unproven "surrogate" parameters, non-detects at the extraction well, and limited sampling. As a result, a treatment-technique type of approach has been utilized to describe subsurface and operational conditions that result in effective RBF. While it is generally understood that parameters such as ionic strength, the presence of natural organic matter (NOM), and media size and shape characteristics affect pathogen transport in porous media, one major limiting factor in the development of regulatory credits and predictive models is the lack of understanding of the concurrent effects of such parameters. To provide guidance for assessing the efficacy of RBF processes, the present investigation is focused on evaluating the concurrent effects of these parameters on pathogen transport in RBF environments. This work details the complete outcomes of a factorial experimental investigation of the concurrent impacts of the four parameters: ionic strength, NOM concentration, grain size, and uniformity coefficient on pathogen and surrogate transport in porous media. Duplicate column studies have been conducted to evaluate the transport of Cryptosporidium oocysts and Salmonella typhimurium bacteria in saturated sandy environments; PR772 bacteriophage, and 4.5 ?m and 1.5 ?m microspheres are also being used as surrogates for pathogen transport. The strain of Salmonella was selected due to the direct link to human illness in the Grand River watershed. Preliminary results indicate that ionic strength effects are greater than NOM effects. Grain size also significantly impacts pathogen transport. Experiments conducted at rates relevant to both GWUDI and conventional filtration systems have indicated that removals of 4.5 ?m microspheres appear to be somewhat reliable surrogate indicators of oocyst removal. No apparent correlation between oocyst removals and removals of bacteria (Bacillus spores) was observed, underscoring that relying on assumed correlation between removals of surrogate parameters target organisms may not be appropriate during RBF investigations.

  10. The S-enantiomer of R, S-citalopram, increases inhibitor binding to the human serotonin transporter by an allosteric mechanism. : Comparison with other serotonin transporter inhibitors.

    DEFF Research Database (Denmark)

    Chen, Fenghua; Larsen, Mads

    2005-01-01

    The interaction of the S- and R-enantiomers (escitalopram and R-citalopram) of citalopram, with high- and low-affinity binding sites in COS-1 cell membranes expressing human SERT (hSERT) were investigated. Escitalopram affinity for hSERT and its 5-HT uptake inhibitory potency was in the nanomolar range and approximately 40-fold more potent than R-citalopram. Escitalopram considerably stabilised the [3H]-escitalopram/SERT complex via an allosteric effect at a low-affinity binding site. The stereoselectivity between escitalopram and R-citalopram was approximately 3:1 for the [3H]-escitalopram/hSERT complex. The combined effect of escitalopram and R-citalopram was additive. Paroxetine and sertraline mainly stabilised the [3H]-paroxetine/hSERT complex. Fluoxetine, duloxetine and venlafaxine have only minor effects. 5-HT stabilised the [125I]-RTI-55, [3H]-MADAM, [3H]-paroxetine, [3H]-fluoxetine and [3H]-venlafaxine/SERT complex to some extent. Thus, escitalopram shows a unique interaction with the hSERT compared with other 5-HT reuptake inhibitors (SSRIs) and, in addition to its 5-HT reuptake inhibitory properties, displays a pronounced effect via an affinity-modulating allosteric site.

  11. The S-enantiomer of R,S-citalopram, increases inhibitor binding to the human serotonin transporter by an allosteric mechanism. Comparison with other serotonin transporter inhibitors.

    DEFF Research Database (Denmark)

    Chen, Fenghua; Larsen, Mads Breum

    2005-01-01

    The interaction of the S- and R-enantiomers (escitalopram and R-citalopram) of citalopram, with high- and low-affinity binding sites in COS-1 cell membranes expressing human SERT (hSERT) were investigated. Escitalopram affinity for hSERT and its 5-HT uptake inhibitory potency was in the nanomolar range and approximately 40-fold more potent than R-citalopram. Escitalopram considerably stabilised the [3H]-escitalopram/SERT complex via an allosteric effect at a low-affinity binding site. The stereoselectivity between escitalopram and R-citalopram was approximately 3:1 for the [3H]-escitalopram/hSERT complex. The combined effect of escitalopram and R-citalopram was additive. Paroxetine and sertraline mainly stabilised the [3H]-paroxetine/hSERT complex. Fluoxetine, duloxetine and venlafaxine have only minor effects. 5-HT stabilised the [125I]-RTI-55, [3H]-MADAM, [3H]-paroxetine, [3H]-fluoxetine and [3H]-venlafaxine/SERT complex to some extent. Thus, escitalopram shows a unique interaction with the hSERT compared with other 5-HT reuptake inhibitors (SSRIs) and, in addition to its 5-HT reuptake inhibitory properties, displays a pronounced effect via an affinity-modulating allosteric site. Udgivelsesdato: 2005-Mar

  12. Comparison of carrier transport mechanism under UV/Vis illumination in an AZO photodetector and an AZO/p-Si heterojunction photodiode produced by spray pyrolysis

    International Nuclear Information System (INIS)

    In this study, Aluminum doped Zinc Oxide (AZO) layer is deposited on p-type silicon (p-Si) by spray pyrolysis method to fabricate ultraviolet-visible (UV/Vis) photodetector as Al doping process can have positive effect on the photodetector performance. Morphology, crystalline structure, and Al concentration of AZO layer are investigated by SEM, XRD, and EDX. The goal of this study is to analyze the mechanism of carrier transport by means of current-voltage characteristics under UV/Vis illumination in two cases: (a) electrodes connected to the surface of AZO layer and (b) electrodes connected to cross section of heterojunction (AZO/p-Si). Measurements indicate that the AZO/p-Si photodiode exhibits a higher photocurrent and lower photoresponse time under visible illumination with respect to AZO photodetector; while under UV illumination, the above result is inversed. Besides, the internal junction field of AZO/p-Si heterojunction plays an important role on this mechanism

  13. Sub-band transport mechanism and switching properties for resistive switching nonvolatile memories with structure of silver/aluminum oxide/p-type silicon

    International Nuclear Information System (INIS)

    In this paper, we discuss a model of sub-band in resistive switching nonvolatile memories with a structure of silver/aluminum oxide/p-type silicon (Ag/AlxOy/p-Si), in which the sub-band is formed by overlapping of wave functions of electron-occupied oxygen vacancies in AlxOy layer deposited by atomic layer deposition technology. The switching processes exhibit the characteristics of the bipolarity, discreteness, and no need of forming process, all of which are discussed deeply based on the model of sub-band. The relationships between the SET voltages and distribution of trap levels are analyzed qualitatively. The semiconductor-like behaviors of ON-state resistance affirm the sub-band transport mechanism instead of the metal filament mechanism

  14. Flow pathways and nutrient transport mechanisms drive hydrochemical sensitivity to climate change across catchments with different geology and topography

    OpenAIRE

    Crossman, J; Futter, M. N.; P. G. Whitehead; E. Stainsby; H. M. Baulch; Jin, L.; Oni, S. K.; Wilby, R. L.; Dillon, P. J.

    2014-01-01

    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 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 p...

  15. Evolutionary Origin of the Mitochondrial Cholesterol Transport Machinery Reveals a Universal Mechanism of Steroid Hormone Biosynthesis in Animals

    OpenAIRE

    Fan, Jinjiang; Papadopoulos, Vassilios

    2013-01-01

    Steroidogenesis begins with the transport of cholesterol from intracellular stores into mitochondria via a series of protein-protein interactions involving cytosolic and mitochondrial proteins located at both the outer and inner mitochondrial membranes. In adrenal glands and gonads, this process is accelerated by hormones, leading to the production of high levels of steroids that control tissue development and function. A hormone-induced multiprotein complex, the transduceosome, was recently ...

  16. Three different regulatory mechanisms enable yeast hexose transporter (HXT) genes to be induced by different levels of glucose.

    OpenAIRE

    Ozcan, S.; Johnston, M.

    1995-01-01

    The HXT genes (HXT1 to HXT4) of the yeast Saccharomyces cerevisiae encode hexose transporters. We found that transcription of these genes is induced 10- to 300-fold by glucose. Analysis of glucose induction of HXT gene expression revealed three types of regulation: (i) induction by glucose independent of sugar concentration (HXT3); (ii) induction by low levels of glucose and repression at high glucose concentrations (HXT2 and HXT4); and (iii) induction only at high glucose concentrations (HXT...

  17. Ab initio study of evolution of mechanical and transport properties of clean and contaminated Au nanowires along the deformation path.

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Pavel; Pérez, R.; Ortega, J.; Flores, F.

    2008-01-01

    Ro?. 77, ?. 11 (2008), 115447/1-115447/11. ISSN 1098-0121 R&D Projects: GA AV ?R KAN400100701; GA AV ?R IAA100100616; GA MŠk 1K05020; GA AV ?R IAA1010413 Institutional research plan: CEZ:AV0Z10100521 Keywords : electronic transport in nanoscale materials and structures * ab initio calculations of adsorbate structure and reactions * nanoscale contacts Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008

  18. Turbine main engines

    CERN Document Server

    Main, John B; Herbert, C W; Bennett, A J S

    1965-01-01

    Turbine Main Engines deals with the principle of operation of turbine main engines. Topics covered include practical considerations that affect turbine design and efficiency; steam turbine rotors, blades, nozzles, and diaphragms; lubricating oil systems; and gas turbines for use with nuclear reactors. Gas turbines for naval boost propulsion, merchant ship propulsion, and naval main propulsion are also considered. This book is divided into three parts and begins with an overview of the basic mode of operation of the steam turbine engine and how it converts the pressure energy of the ingoing ste

  19. A POTluck of peptide transporters

    OpenAIRE

    Nissen, Poul

    2012-01-01

    Diet-derived peptides are taken up by conserved proton-dependent oligopeptide transporters. Two papers on crystal structures of bacterial transporters in different conformations now shed light on the transport mechanism.

  20. Changes in the source and transport mechanism of terrigenous input to the Indian sector of Southern Ocean during the late Quaternary and its palaeoceanographic implications

    Indian Academy of Sciences (India)

    M Thamban; S S Naik; R Mohan; A Rajakumar; N Basavaiah; Witty D'Souza; Sarita Kerkar; M M Subramaniam; M Sudhakar; P C Pandey

    2005-10-01

    Changes in the terrigenous sediment source and transport mechanisms during the late Quaternary have been investigated using four sediment cores within the Indian sector of Southern Ocean, using the magnetic susceptibility (MS)and sedimentological records.Sediments deposited during the Holocene and other interglacial periods were characterised by low MS,low sand content, reduced ice-rafted detritus (IRD)input and increased illite possibly transported via hydrographic advection from the south.The glacial intervals are characterised by high MS,high sand content, increased IRD input and reduced illite clays,derived from both local as well as Antarctic sources. Signi?cant reduction in clay fraction and illite content during glacials suggests that the erosive and transporting capabilities of the deep and bottom waters could have reduced compared to the interglacial times.The changes in terrigenous in ?ux to this region were signi ?cantly in ?uenced by the rhythmic glacial –interglacial ?uctuations in bottom circulation and the position of the Polar Front.

  1. Evolution of planet crossing asteroids in the inner Main Belt

    International Nuclear Information System (INIS)

    We studied the dynamical evolution of asteroids in terrestrial planet crossing orbits, located between 2.1 and 2.5 AU. The evolution is analyzed by direct numerical integration of massless particles under the gravitational influence of all planets from Venus to Neptune. The simulations include the Yarkovsky effect, introduced as a non conservative force that produces a slow variation of the average orbital semimajor axis. Our analysis focuses on the test particles that can reach the middle and outer regions of the Main Belt (semimajor axis > 2.5 AU) during their evolution, since these may be relevant for understanding the transport mechanisms of asteroids from the inner Belt. These mechanisms could help to explain, for example, the existence of basaltic asteroids beyond 2.5 AU assuming that these bodies originate in the Vesta family, located at ? 2.3 AU. We found that, although some orbits that reach the middle and outer regions of the Belt can become temporarily detached from the planet crossing regime, and may have their orbital eccentricities damped due to capture at some mean motion resonances, such orbits survive for only a few hundred thousand years and, ultimately, the test particles return to the planet crossing regime being eventually discarded by close encounters with the planets. These results seem to indicate that a transport mechanism based only on planetary encounters and resonant capture might not be efficient enough to justify the presence of basaltic asteroids beyond 2.5 AU.

  2. Evolution of planet crossing asteroids in the inner Main Belt

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, A O; Roig, F, E-mail: anderson@on.br [Observatorio Nacional, Rio de Janeiro, 20921-400, RJ (Brazil)

    2011-03-01

    We studied the dynamical evolution of asteroids in terrestrial planet crossing orbits, located between 2.1 and 2.5 AU. The evolution is analyzed by direct numerical integration of massless particles under the gravitational influence of all planets from Venus to Neptune. The simulations include the Yarkovsky effect, introduced as a non conservative force that produces a slow variation of the average orbital semimajor axis. Our analysis focuses on the test particles that can reach the middle and outer regions of the Main Belt (semimajor axis > 2.5 AU) during their evolution, since these may be relevant for understanding the transport mechanisms of asteroids from the inner Belt. These mechanisms could help to explain, for example, the existence of basaltic asteroids beyond 2.5 AU assuming that these bodies originate in the Vesta family, located at {approx} 2.3 AU. We found that, although some orbits that reach the middle and outer regions of the Belt can become temporarily detached from the planet crossing regime, and may have their orbital eccentricities damped due to capture at some mean motion resonances, such orbits survive for only a few hundred thousand years and, ultimately, the test particles return to the planet crossing regime being eventually discarded by close encounters with the planets. These results seem to indicate that a transport mechanism based only on planetary encounters and resonant capture might not be efficient enough to justify the presence of basaltic asteroids beyond 2.5 AU.

  3. The Maine Music Box

    OpenAIRE

    Lutz, Marilyn; Gallucci, Laura

    2005-01-01

    The paper describes the Maine Music Box and examines its potential as a tool for teaching and learning music. Pedagogical concepts are demonstrated using MIDI, Scorch, image and streaming video files.

  4. 2004 Maine Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata document describes the collection and processing of Light Detection and Ranging (LIDAR) data over an area along the coast of Maine. Data was collected...

  5. Main condenser system

    International Nuclear Information System (INIS)

    Real time simulation of the Washington Nuclear Project Unit 2 (WNP-2) Main Condenser System, using a SEL 32/77 computer, is described herein. The system interacts with the main steam, condensate and feedwater, and circulating water systems. The condenser evacuation system is included as a part of the main condenser system simulation. The main condenser is a single pass, three-bank divided waterbox type surface condenser which acts as a heat sink for condensing turbine exhaust and bypass steam, a receiver for miscellaneous drains, and a storage for condensate. It is internally divided into three pressure zones with three associated hotwells. Three parallel tube bundles carrying circulating water for cooling purposes run across three pressure zone compartments. Water in the hotwells is free to cross over through the bottom of the condenser. The evacuation system consists of vacuum pumps to evacuate air during the startup and steam jet ejectors to maintain the vacuum during normal operation

  6. Thermal stability of the current transport mechanisms in Ni-based Ohmic contacts on n- and p-implanted 4H-SiC

    International Nuclear Information System (INIS)

    Studying the temperature dependence of the electrical properties of Ohmic contacts formed on ion-implanted SiC layers is fundamental to understand and to predict the behaviour of practical devices. This paper reports the electrical characterization, as a function of temperature, of Ni-based Ohmic contacts, simultaneously formed on both n- or p-type implanted 4H-SiC. A structural analysis showed the formation of the Ni2Si phase after an annealing leading to Ohmic behaviour. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism (TFE) dominates the current transport for contacts formed on p-type material, while a field emission (FE) is likely occurring in the contacts formed on n-type implanted SiC. The values of the barrier height were 0.75 eV on p-type material and 0.45 eV on n-type material. The thermal stability of the current transport mechanisms and related physical parameters has been demonstrated upon a long-term (up to 95 h) cycling in the temperature range 200–400 °C. (papers)

  7. Differential rotation of main sequence F stars

    OpenAIRE

    Kueker, M.; Ruediger, G.

    2004-01-01

    The differential rotation of a 1.2 $M_\\odot$ zero age MS star (spectral type F8) is computed and the results are compared with those from a similar model of the Sun. The rotation pattern is determined by solving the Reynolds equation including the convective energy transport. The latter is anisotropic due to the Coriolis force causing a horizontal temperature gradient of ~ 7 K between the poles and the equator. Comparison of the transport mechanisms of angular momentum (the ...

  8. Mechanical and thermal processing effects on crystal defects and thermoelectric transport properties of Bi{sub 2}(Se,Te){sub 3} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Meng-Pei; Liao, Chien-Neng, E-mail: cnliao@mx.nthu.edu.tw

    2013-09-15

    Highlights: •Mechanically and thermally induced crystal defects in Bi{sub 2}(Se,Te){sub 3} are studied. •Donor-type Te vacancy is the major crystal defect caused by mechanical milling. •A two-step thermal annealing improves thermoelectric power factor of Bi{sub 2}(Se,Te){sub 3}. -- Abstract: Charged crystal defects generally play the roles of electron donor or acceptor and affect thermoelectric properties of bismuth telluride compounds profoundly. In this study the effects of ball milling, pressing and thermal annealing on populations of various crystal defects and electrical/thermal transport properties of Bi{sub 2}(Se,Te){sub 3} compounds are investigated. It has been found that abundant donor-type Te vacancies are introduced during mechanical milling process, leading to high electron concentration and reduced carrier mobility for cold-pressed Bi{sub 2}(Se,Te){sub 3}. A two-step annealing method consisting of pre-press and post-press annealing is presented for improving thermoelectric power factor while retaining low thermal conductivity of Bi{sub 2}(Se,Te){sub 3} compounds by tweaking crystal defect population and carrier scattering mechanism.

  9. Molecular mechanisms of the epithelial transport of toxic metal ions, particularly mercury, cadmium, lead, arsenic, zinc, and copper. Progress report, January 1, 1979-December 31, 1979

    International Nuclear Information System (INIS)

    The mechanism of lead transport is presented, and especially the particular similarities or dissimilarities between lead and calcium in this process. The absorption of these metals was determined cockerels, raised on a commercial diet or on a specified diet, using in vivo ligated loop procedure. The dose administered into the loop contained 0.5 ?Ci 203Pb (and/or 0.1 ?Ci 47Ca), and 0.01 mM lead acetate (and/or mM CaCl2) in 0.5 ml 0.15 M NaCl,pH 6.5. It was shown that lead is rapidly taken up by the mucosal tissue, and slowly transferred into the body, whereas less calcium is retained by the tissue and the transfer of calcium is many times as effective as that for lead. They appear to respond in a similar manner to a low calcium intake and vitamin D treatment. Increasing luminal stable lead concentration significantly reduced the percentage of radiolead significantly reduced the percentage of radiolead absorbed, but did not affect the absorption of calcium. Also, vitamin D enhanced the transfer of plasma 47Ca into the lumen but did not affect the transfer of plasma 203Pb. Intravenous administration of 1,25(OH)2CC to rachitic chicks enhanced calcium and lead absorption, but the maximal absorption of these metals occurred at slightly different times after administering this metabolite, indicating that two different transport systems may be involved. It was concluded that lead is transported across the epithelial wall by a passive diffusion and this process is affected by vitamin D in a similar manner as this vitamin affects the diffusional component of calcium transport

  10. Molecular mechanisms of the epithelial transport of toxic metal ions, particularly mercury, cadmium, lead, arsenic, zinc, and copper. Progress report, January 1, 1979-December 31, 1979

    International Nuclear Information System (INIS)

    The purpose of the present studies was to elucidate the mechanism of lead transport, and especially the particular similarities or dissimilarities between lead and calcium in this process. The absorption of these metals was determined in 3-week old White Leghorn cockerels, raised on a commercial diet or on a specified diet, using in vivo ligated loop procedure. The dose administered into the loop contained 0.5 ?Ci 203Pb (and/or 0.1 ?Ci 47Ca), and 0.01 mM lead acetate (and/or 1 mM CaCl2) in 0.5 ml 0.15 M NaCl,pH 6.5. It was shown that lead is rapidly taken up by the mucosal tissue, and slowly transferred into the body, whereas less calcium is retained by the tissue and the transfer of calcium is many times as effective as that for lead. They appear to respond in a similar manner to a low calcium intake and vitamin D treatment. Certain differences were, however, observed in the absorption process. Increasing luminal stable lead concentration from 0.01 to 1.00 mM Pb, significantly reduced the percentage of radiolead absorbed, but did not affect the absorption of calcium. Also, vitamin D enhanced the transfer of plasma 47Ca into the lumen but did not affect the transfer of plasma 203Pb. Intravenous administration of 1,25(OH)2CC to rachitic chicks enhanced calcium and lead absorption, but the maximal absorption of these metals occurred at slightly different times after administering this metabolite, and the effect on calcium outlasted that on lead, indicating that two different transport systems may be involved. It was concluded that lead is transported across the epithelial wall by a passive diffusion and this process is affected by vitamin D in a similar manner as this vitamin affects the diffusional component of calcium transport

  11. 49 CFR 236.831a - Track, main.

    Science.gov (United States)

    2010-10-01

    ...Transportation 4 2010-10-01 2010-10-01 false Track, main. 236.831a Section 236.831a Transportation...DEVICES, AND APPLIANCES Definitions § 236.831a Track, main. A track, other than auxiliary track, extending through...

  12. Intestinal Phosphate Transport

    OpenAIRE

    Sabbagh, Yves; Giral, Hector; Caldas, Yupanqui; Levi, Moshe; Schiavi, Susan C.

    2011-01-01

    Phosphate is absorbed in the small intestine by at least two distinct mechanisms: paracellular phosphate transport which is dependent on passive diffusion and active transport which occurs through the sodium-dependent phosphate co-transporters. Despite evidence emerging for other ions, regulation of the phosphate specific paracellular pathways remains largely unexplored. In contrast, there is a growing body of evidence that active transport through the sodium-dependent phosphate co-transporte...

  13. Vesicular Glutamate Transporter 2 Expression in the Rat Pineal Gland: Detailed Analysis of Expression Pattern and Regulatory Mechanism

    Science.gov (United States)

    Yoshida, Sachine; Hisano, Setsuji

    Melatonin, a hormone secreted by the pineal gland, is closely related physiologically to circadian rhythm, sleep and reproduction, and also psychiatrically to mood disorders in humans. Under circadian control, melatonin secretion is modulated via nocturnal autonomic (adrenergic) stimulation to the gland, which expresses vesicular glutamate transporter (VGLUT) 1, VGLUT2 and a VGLUT1 splice variant (VGLUT1v), glutamatergic markers. Expression of VGLUT2 gene and protein in the intact gland has been reported to exhibit a rhythmic change during a day. To study VGLUT2 expression is under adrenergic control, we here performed an in vitro experiment using dispersed pineal cells of rats. Stimulation of either ?-adrenergic receptor or cAMP production to the pineal cells was shown to increase mRNA level of VGLUT2, but not VGLUT1 and VGLUT1v. Because an ability of glutamate to inhibit melatonin production was previously reported in the cultured gland, it is likely that pineal VGLUT2 transports glutamate engaged in the inhibition of melatonin production.

  14. Unusual effects of monocarboxylic acids on the structure and on the transport and mechanical properties of chitosan films.

    Science.gov (United States)

    Chen, Fei; Gällstedt, Mikael; Olsson, Richard T; Gedde, Ulf W; Hedenqvist, Mikael S

    2015-11-01

    The purpose of this study was to study the transport of monocarboxylic acids in chitosan films, since this is important for understanding and predicting the drying kinetics of chitosan from aqueous solutions. Despite the wealth of data on chitosan films prepared from aqueous monocarboxylic acid solutions, this transport has not been reported. Chitosan films were exposed to formic, acetic, propionic and butyric acid vapours, it was found that the rate of uptake decreased with increasing molecular size. The equilibration time was unexpectedly long, especially for propionic and butyric acid, nine months. A clear two-stage uptake curve was observed for propionic acid. Evidently, the rate of uptake was determined by acid-induced changes in the material. X-ray diffraction and infrared spectroscopy indicated that the structure of the chitosan acetate and buffered chitosan films changed during exposure to acid and during the subsequent drying. The dried films previously exposed to the acid showed less crystalline features than the original material and a novel repeating structure possibly involving acid molecules. The molar mass of the chitosan decreased on exposure to acid but tensile tests revealed that the films were always ductile. The films exposed to acid vapour (propionic and butyric acid) for the longest period of time were insoluble in the size-exclusion chromatography eluent, and they were also the most ductile/extensible of all samples studied. PMID:26256366

  15. TransECO{sub 2}. Demonstration project: Environmental and economic benefits by environmental management in freight transportation. Main report; TransECO{sub 2}. Demonstrationsprojekt: Miljoemaessige og oekonomiske benefits ved miljoestyring i godstransport. Hovedrapport

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The aim of the transECO{sub 2} project has was to carry out cooperation projects between companies in order to demonstrate an effect for the environment and for the economy of the companies (earnings and costs) of environmental management related to transportation of goods. 10 demonstration projects were carried thorugh in cooperation with 14 companies. 8 subjects were analysed through the transECO{sub 2} project: 1. Environmental data; 2. Benefits from the environmental management work; 3. Use of new technology; 4. Cooperation; 5. Environment and logistics; 6. Education and competence; 7. Environment and business strategy; 8. Environmental statement/tagging. (EHS)

  16. Mechanical properties degradation in a Cr-Mo low-alloy steel pipe after prolonged use for gas transport in a power plant station

    Directory of Open Access Journals (Sweden)

    Mihai, D.

    2002-12-01

    Full Text Available Some prolonged exposure effects at the high temperatures and pressures characteristic to the steam transport in power station, have been revealed in a 12HMF GOST (13CrMo44 DIN Cr-Mo low alloy steel pipes, at both macro and microstructural level, by mechanical tests and optical microscopy. After 128625 functioning hours, a marked mechanical degradation was noticed by the values of tensile strength, hardness and toughness that decreased with 14-16 %, 45-48 % and 47-59 %, respectively. This lose of mechanical properties was correlated on one hand to the coalescence of ferrite grains and pearlite islets and on the other hand to a decrease in the anisotropy of the grains morphology.

    Se han determinado algunos efectos de la exposición prolongada a temperaturas y presiones altas, características del transporte del vapor en una central térmica, en las conducciones de acero 12HMF GOST (13CrMo44 DIN Cr-Mo de baja aleación, a nivel macro y microestructural a través de ensayos mecánicos y microscopia óptica. Tras 128.625 h de servicio, se ha notado una notable degradación mecánica en los valores de la resistencia a la rotura, de la dureza y de la resilencia, que han disminuido entre un 14-16 %, un 45-48 % y un 47-59 %, respectivamente. La degradación mecánica se correlacionó, por una parte, con la coalescencia de los granos de ferrita y de las islas de perlita y, por otra, con el decrecimiento en la anisotropía de la morfología de los granos.

  17. Different transport mechanisms for cadmium and mercury in Caco-2 cells: inhibition of Cd uptake by Hg without evidence for reciprocal effects

    International Nuclear Information System (INIS)

    Cadmium/Hg interactions have been studied in the TC7 clone of the enterocytic-like Caco-2 cells to test the hypothesis that these metals may compete for intestinal transport. Comparison of the kinetic parameter values for 203Hg(II) and 109Cd(II) uptake in a serum-free medium revea