Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Transport

  • acid transport
  • active transport
  • adenosine transport
  • advective heat transport
  • advective transport
  • ambulance transport
  • amino acid transport
  • angular momentum transport
  • anion transport
  • anterograde transport
  • atmospheric transport
  • auxin transport
  • bicarbonate transport
  • bidirectional transport
  • bile acid transport
  • calcium transport
  • carbon transport
  • carnitine transport
  • carrier transport
  • cation transport
  • charge carrier transport
  • charge transport
  • charge-carrier transport
  • chemical transport
  • chemical vapor transport
  • chloride transport
  • cholesterol transport
  • contaminant transport
  • convective transport
  • current transport
  • de transport
  • diffusive transport
  • dispersive transport
  • distance transport
  • dna transport
  • drug transport
  • efficient transport
  • efflux transport
  • electrical transport
  • electrolyte transport
  • electron transport
  • electronic transport
  • fatty acid transport
  • fluid transport
  • gas transport
  • glucose transport
  • glutamate transport
  • heat transport
  • hole transport
  • intracellular transport
  • ion transport
  • ionic transport
  • iron transport
  • k+ transport
  • larval transport
  • lateral transport
  • lipid transport
  • long distance transport
  • long-distance transport
  • lymphatic transport
  • mass transport
  • material transport
  • melanosome transport
  • membrane transport
  • metal transport
  • mitochondrial electron transport
  • mitochondrial transport
  • moisture transport
  • molecular transport
  • momentum transport
  • na+ transport
  • net transport
  • nuclear transport
  • nucleocytoplasmic transport
  • nutrient transport
  • o2 transport
  • oxygen transport
  • particle transport
  • passive transport
  • phosphate transport
  • photosynthetic electron transport
  • physical vapor transport
  • polar auxin transport
  • pollutant transport
  • protein transport
  • proton transport
  • public transport
  • quantum transport
  • radial transport
  • rapid transport
  • reactive transport
  • retrograde transport
  • reverse cholesterol transport
  • sediment transport
  • seed transport
  • sodium transport
  • solute transport
  • spin transport
  • substrate transport
  • tracer transport
  • transcellular transport
  • transmembrane transport
  • vapor transport
  • vapor-phase transport
  • vesicle transport
  • vesicular transport
  • vitro transport
  • water transport

  • Terms modified by Transport

  • transport activity
  • transport analysis
  • transport behavior
  • transport capability
  • transport capacity
  • transport chain
  • transport channel
  • transport characteristic
  • transport coefficient
  • transport condition
  • transport cost
  • transport data
  • transport distance
  • transport efficiency
  • transport equation
  • transport equilibration
  • transport event
  • transport experiment
  • transport fuel
  • transport function
  • transport increase
  • transport industry
  • transport infrastructure
  • transport inhibition
  • transport inhibitor
  • transport kinetics
  • transport layer
  • transport limitation
  • transport machinery
  • transport material
  • transport measurement
  • transport mechanism
  • transport medium
  • transport method
  • transport mode
  • transport model
  • transport modeling
  • transport models
  • transport network
  • transport parameter
  • transport pathway
  • transport pattern
  • transport phenomenoN
  • transport policy
  • transport potential
  • transport problem
  • transport process
  • transport property
  • transport protein
  • transport protocol
  • transport rate
  • transport regime
  • transport requirement
  • transport route
  • transport sector
  • transport services
  • transport simulation
  • transport studies
  • transport substrate
  • transport system
  • transport team
  • transport technique
  • transport time
  • transport vehicle
  • transport velocity

  • Selected Abstracts


    JOURNAL OF PHYCOLOGY, Issue 4 2000
    G. Jason Smith
    No abstract is available for this article. [source]


    Brian S. Caruso
    ABSTRACT: The U.S. Environmental Protection Agency (USEPA) Water Quality Analysis Simulation Program (WASP5) was used to model the transport and sediment/water interactions of metals under low flow, steady state conditions in Tenmile Creek, a mountain stream supplying drinking water to the City of Helena, Montana, impacted by numerous abandoned hard rock mines. The model was calibrated for base flow using data collected by USEPA and validated using data from the U.S. Geological Survey (USGS) for higher flows. It was used to assess metals loadings and losses, exceedances of Montana State water quality standards, metals interactions in stream water and bed sediment, uncertainty in fate and transport processes and model parameters, and effectiveness of remedial alternatives that include leaving contaminated sediment in the stream. Results indicated that during base flow, adits and point sources contribute significant metals loadings to the stream, but that shallow ground water and bed sediment also contribute metals in some key locations. Losses from the water column occur in some areas, primarily due to adsorption and precipitation onto bed sediments. Some uncertainty exists in the metal partition coefficients associated with sediment, significance of precipitation reactions, and in the specific locations of unidentified sources and losses of metals. Standards exceedances are widespread throughout the stream, but the model showed that remediation of point sources and mine waste near water courses can help improve water quality. Model results also indicate, however, that alteration of the water supply scheme and increasing base flow will probably be required to meet all water quality standards. [source]


    Edward H. Smith
    ABSTRACT: Levee sump systems are used by many riverine communities for temporary storage of urban wet weather flows. The hydrologic performance and transport of stormwater pollutants in sump systems, however, have not been systematically studied. The objective of this paper is to present a case study to demonstrate development and application of a procedure for assessing the hydraulic performance of flood control sumps in an urban watershed. Two sumps of highly variable physical and hydraulic characteristics were selected for analysis. A hydrologic modeling package was used to estimate the flow hydrograph for each outfall as part of the flow balance for the sump. To validate these results, a water balance was used to estimate the total runoff using sump operational data. The hydrologic model calculations provide a satisfactory estimate of the total runoff and its time-distribution to the sump. The model was then used to estimate pollutant loads to the sump and to the river. Although flow of stormwater through a sump system is regulated solely by flood-control requirements, these sumps may function as sedimentation basins that provide purification of stormwater. A sample calculation of removals of several conventional pollutants in the target sumps using a mass balance approach is presented. [source]


    Abstract In this paper, the effect of sand particles transport caused by wind blowing and its role in the land degradation and desertification process is considered. For the modeling of the 3D landscape, a grayscale height map has been used, the vegetation has been modeled using a Lindenmayer system, and the sand particles have been modeled as a 3D mesh-free particles system. It was assumed that both the sand motion and the wind motion are incompressible continuum systems and their behavior follows the Navier,Stokes equations. To simulate the sand transport, the Navier,Stokes equations are discretized using the moving particle Semi-implicit (MPS) method. Different types of revegetation patterns (windbreakers) have been used to show some effective measures preventing soils from erosion. [source]

    Call for Papers for a Special Issue on TRANSPORT, November 2010, Deadline for submission: April 15, 2010

    Article first published online: 4 APR 2010
    No abstract is available for this article. [source]


    Ramesh C Khanal
    SUMMARY 1Calcium (re)absorption occurs in epithelia, including the intestine, kidney, mammary glands, placenta and gills (in the case of fish). 2Calcium is transported across epithelia by two transport mechanisms, paracellular and transcellular, and the movement is regulated by a complex array of transport processes that are mediated by hormonal, developmental and physiological factors involving the gastrointestinal tract, bone, kidney and the parathyroids. 3Clear understanding of the calcium transport pathways and their endocrine regulation is critical for minimizing various metabolic and health disorders at different physiological stages. Here, we first briefly review the calcium transport mechanisms before discussing in detail the endocrine factors that regulate calcium transport in the epithelia. [source]

    Replica Exchange Light Transport

    Shinya Kitaoka
    I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism; I.3.3 [Computer Graphics]: Picture/Image Generation Abstract We solve the light transport problem by introducing a novel unbiased Monte Carlo algorithm called replica exchange light transport, inspired by the replica exchange Monte Carlo method in the fields of computational physics and statistical information processing. The replica exchange Monte Carlo method is a sampling technique whose operation resembles simulated annealing in optimization algorithms using a set of sampling distributions. We apply it to the solution of light transport integration by extending the probability density function of an integrand of the integration to a set of distributions. That set of distributions is composed of combinations of the path densities of different path generation types: uniform distributions in the integral domain, explicit and implicit paths in light (particle/photon) tracing, indirect paths in bidirectional path tracing, explicit and implicit paths in path tracing, and implicit caustics paths seen through specular surfaces including the delta function in path tracing. The replica-exchange light transport algorithm generates a sequence of path samples from each distribution and samples the simultaneous distribution of those distributions as a stationary distribution by using the Markov chain Monte Carlo method. Then the algorithm combines the obtained path samples from each distribution using multiple importance sampling. We compare the images generated with our algorithm to those generated with bidirectional path tracing and Metropolis light transport based on the primary sample space. Our proposing algorithm has better convergence property than bidirectional path tracing and the Metropolis light transport, and it is easy to implement by extending the Metropolis light transport. [source]

    On Kinetic Effects during Parallel Transport in the SOL

    D. Tskhakaya
    Abstract 1D kinetic (PIC) and fluid simulations have been performed in order to study boundary conditions and heat flux and viscosity limiting coefficients in the inter-ELM and ELMy SOLs. Simulated plasma parameters correspond to the JET SOL under different conditions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Ion Particle Transport in the Tokamak Edge Plasma

    W. M. Stacey
    Abstract A generalized pinch-diffusion transport relation previously derived from momentum conservation is combined with the continuity equation to derive a "generalized diffusion theory" for ion particle transport in the tokamak plasma edge inside the separatrix. The resulting generalized diffusion coefficients are evaluated for a representative experiment. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Blob Transport in the Tokamak Scrape-off-Layer

    D. A. D'Ippolito
    Abstract Recent experimental evidence suggests the importance of fast radial plasma transport in the scrape-off-layer (SOL) of tokamaks. The outward transport appears to be convective rather than diffusive, extends into the far SOL, and can produce significant recycling from the main-chamber walls, partially bypassing the divertor. A plausible theoretical mechanism to explain this phenomenon is the radial transport of "blobs" of locally dense plasma created by turbulent processes. A related process is the inward transport of "holes" of reduced density plasma, which provides a mechanism for rapid inward transport of impurities. The blob model is also consistent with the spatial and temporal intermittency and the non-Gaussian statistics observed in the SOL plasma. This paper reviews the present status of blob theory, including analytic models and simulations, and discusses the preliminary comparisons of the blob model with experimental data. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Insulin-treated diabetes and driving in the UK

    DIABETIC MEDICINE, Issue 6 2002
    G. Gill
    Abstract Diabetes, and particularly insulin-treated diabetes, has important implications for motor vehicle driving, largely because of its association with potential hypoglycaemia. For this reason, most countries operate some driving restrictions on insulin-treated diabetic patients, as well as systems of intermittent reassessment of hypoglycaemic risk. In the UK, regulations are operated by the Driver and Vehicle Licensing Agency (DVLA), which is an agency of the Department of the Environment, Transport and the Regions (DETR). They are supported by an Expert Panel which advises the Secretary of State on diabetes-related issues relating to fitness to drive. The patient organization Diabetes UK is also concerned with diabetes and driving issues, largely from a position of lobbying policy-influencers and supporting individual cases. All parties involved with diabetes and driving issues recognize the need for more research on the subject, as the current literature is flawed in design, though no convincing excess of accidents amongst diabetic drivers has been conclusively demonstrated. Currently in the UK, Class 2 vehicles (large trucks and passenger vehicles) are barred to diabetic drivers on insulin. European law has recently extended this to so-called C1 (large vans and small lorries) and D1 (minibuses) vehicles, though the law has recently been revised to allow individual consideration for potential diabetic C1 drivers on insulin treatment. Diabetes and insulin-treated diabetes is an emotive and difficult issue, for which a stronger evidence base is urgently needed. [source]

    Telemetry Monitoring during Transport of Low-risk Chest Pain Patients from the Emergency Department: Is It Necessary?

    Adam J. Singer MD
    Abstract Background: Low-risk emergency department (ED) patients with chest pain (CP) are often transported by nurses to monitored beds on telemetry monitoring, diverting valuable resources from the ED and delaying transport. Objectives: To test the hypothesis that transporting low-risk CP patients off telemetry monitoring is safe. Methods: This was a secondary analysis of a prospective, observational cohort of ED patients with low-risk chest pain (no active chest pain, normal or nondiagnostic electrocardiogram, normal initial troponin I) admitted to a non,intensive care unit monitored bed who were transported off telemetry monitor by nonclinical personnel. A protocol allowing transportation of low-risk CP patients off telemetry monitoring to a monitored bed was developed, and an ongoing daily log of patients transported off telemetry was maintained for the occurrence of any adverse events en route to the floor. Adverse events requiring treatment included dysrhythmias, hypotension, syncope, and cardiac arrest. The study population included patients who presented during September,October 2004, whose data were abstracted from the medical records using standardized methodology. A subset of 10% of the medical records were reviewed by a second investigator for interrater reliability. Death, syncope, resuscitation, and dysrhythmias during transport or immediately on arrival to the floor were the outcomes measured. Descriptive statistics and confidence intervals (CIs) were used in data analysis. Results: During the study period, 425 patients had CP of potentially ischemic origin, of whom 322 (75.8%) were low risk and met the inclusion criteria and were transported off monitors. Their mean (±standard deviation) age was 58.3 (±16.0) years; 48.1% were female. During transport from the ED, there was no patient with any adverse events requiring treatment and there was no death (95% CI = 0% to 0.93%). Conclusions: Transportation of low-risk ED chest pain patients off telemetry monitoring by nonclinical personnel to the floor appears safe. This may reduce diversion of ED nurses from the ED, helping to alleviate nursing shortages. [source]

    The influence of plant cover and land use on slope,channel decoupling in a foothill catchment: a case study from the Carpathian Foothills, southern Poland

    Jolanta, chowicz
    Abstract This paper examines the influence of plant cover and land use on slope,channel decoupling in the Stara Rzeka Stream catchment (22·4 km2) and its subcatchment Dworski Potok Stream (0·3 km2). The Stara Rzeka catchment is situated in the marginal part of the Carpathian Foothills and is characterized by a relief of low and medium hills. The catchment is used for agriculture but unlike other foothill catchments, it has a relatively extensive unfragmented area of forests (41·3 per cent). Grasslands and pastures (13·8 per cent) are mainly along the broad and flat valley floor. In the cultivated area (38·5 per cent) of the northern low hill part of the catchment, the fields are long, narrow and separated by boundary strips. They stretch from the hilltops to the valley bottom and are traditionally ploughed along the slopes. The research into slope wash was carried out at six sites downslope (August 1989 to October 1990) and on experimental plots (1989,1991). Transport of suspended matter was determined in the channels of the Stara Rzeka and Dworski Potok Streams (1987,1991). The results show that transport and export of the material on the slopes depend on the morphology of the slope and on the agricultural use of the area. The mosaic of fields which are used differently makes the soil wash process very intensive only if the slopes are ploughed and unprotected by a dense cover of vegetation. The material displaced is mostly accumulated at the foot of the slopes or at the bottom of the valley. Footslope areas and flat valley bottoms covered with grass function as a barrier separating the slope and the river bed. These features generally negate the transfer of slope-originated material to the bed of the stream. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Road pricing: lessons from London

    ECONOMIC POLICY, Issue 46 2006
    Georgina Santos
    SUMMARY Road pricing LESSONS FROM LONDON This paper assesses the original London Congestion Charging Scheme (LCCS) and its impacts, and it simulates the proposed extension which will include most of Kensington and Chelsea. It also touches upon the political economy of the congestion charge and the increase of the charge from £5 to £8 per day. The possibility of transferring the experience to Paris, Rome and New York is also discussed. The LCCS has had positive impacts. This was despite the considerable political influences on the charge level and location. It is difficult to assess the impacts of the increase of the charge from £5 to £8, which took place in July 2005, because no data have yet been released by Transport for London. The proposed extension of the charging zone does not seem to be an efficient change on economic grounds, at least for the specific boundaries, method of charging and level of charging that is currently planned. Our benefit cost ratios computed under different assumptions of costs and benefits are all below unity. Overall, the experience shows that simple methods of congestion charging, though in no way resembling first-best Pigouvian taxes, can do a remarkably good job of creating benefits from the reduction of congestion. Nevertheless, the magnitude of these benefits can be highly sensitive to the details of the scheme, which therefore need to be developed with great care. , Georgina Santos and Gordon Fraser [source]

    Electrochemical Elucidation of the Facilitated Ion Transport Across a Bilayer Lipid Membrane in the Presence of Neutral Carrier Compounds

    ELECTROANALYSIS, Issue 11 2010
    Jun Onishi
    Abstract The ion transport facilitated by neutral carrier compounds (valinomycin, nonactin) has been investigated by cyclic voltammetry in the several electrolyte solutions (KF, KCl, KBr, KNO3, KSCN, KClO4), and we demonstrated the effect of the counter anions on the facilitated transport of K+ from the viewpoint of electroneutrality. Voltammograms for the ion transport were generated at steady state and the current density between W1 and W2, jW1,W2, increased with the absolute value of the applied membrane potential, EW1,W2. Then, the magnitude of jW1,W2 at a certain EW1,W2 increased with the hydrophobicity of the counter anion. It was proved that the logarithm of |jW1,W2|at a certain EW1,W2 is almost proportional to the hydration energy of the counter anion. This indicates that not only K+ but also the counter anion distributes into the BLM. Therefore, the magnitude of jW1,W2 at a certain EW1,W2 increased with an increase of pH, because the hydroxide ion was served as a counter anion. Based on the variation of the zero-current potential in case of various asymmetrical ionic compositions, it is found that the amount of cation transport is much larger than that of anion transport. [source]

    Transport and deformation of droplets in a microdevice using dielectrophoresis

    ELECTROPHORESIS, Issue 4 2007
    Pushpendra Singh Professor
    Abstract In microfluidic devices the fluid can be manipulated either as continuous streams or droplets. The latter is particularly attractive as individual droplets can not only move but also split and fuse, thus offering great flexibility for applications such as laboratory-on-a-chip. We consider the transport of liquid drops immersed in a surrounding liquid by means of the dielectrophoretic force generated by electrodes mounted at the bottom of a microdevice. The direct numerical simulation (DNS) approach is used to study the motion of droplets subjected to both hydrodynamic and electrostatic forces. Our technique is based on a finite element scheme using the fundamental equations of motion for both the droplets and surrounding fluid. The interface is tracked by the level set method and the electrostatic forces are computed using the Maxwell stress tensor. The DNS results show that the droplets move, and deform, under the action of nonuniform electric stresses on their surfaces. The deformation increases as the drop moves closer to the electrodes. The extent to which the isolated drops deform depends on the electric Weber number. When the electric Weber number is small, the drops remain spherical; otherwise, the drops stretch. Two droplets, however, that are sufficiently close to each other, can deform and coalesce, even if the electric Weber number is small. This phenomenon does not rely on the magnitude of the electric stresses generated by the bulk electric field, but instead is due to the attractive electrostatic drop,drop interaction overcoming the surface tension force. Experimental results are also presented and found to be in agreement with the DNS results. [source]

    Lymantria dispar herbivory induces rapid changes in carbon transport and partitioning in Populus nigra

    Benjamin A. Babst
    Abstract We tested for rapid changes in photosynthate transport and partitioning in response to Lymantria dispar (L.) (Lepidoptera: Lymantriidae) (gypsy moth) herbivory in Populus nigra L. (Salicaceae). Transport and partitioning of [11C]-photosynthate from young mature leaves were measured in vivo before and 18 h after leaf chewing by gypsy moth larvae, which were caged on three older leaves. Following herbivory, there was an increase in export speed of recently fixed carbon from younger mature leaves. The increased export speed was due to a quicker transit time of 11C through the leaf, rather than a change in transport speed through the phloem. Additionally, basipetal partitioning of [11C]-photosynthate was increased following herbivory. Neither of these changes was observed in control plants. This enhancement of export occurs even though herbivores are well known to induce increases in carbon allocation to secondary metabolites within leaves. Our results demonstrate that the use of non-destructive imaging of 11C tracer is a powerful tool for examining plant responses to herbivory. Although the mechanisms underlying the rapid increase in carbon flux to stems and roots remain to be elucidated, our results raise the possibility of a coordinated whole plant response to herbivory. Thus, even when the herbivore specializes on only one plant tissue type, a whole plant approach may be key to understanding how plants respond to herbivory. [source]

    Impact of surface thermodynamics on bacterial transport

    Gang Chen
    Microbial surface thermodynamics correlated with bacterial transport in saturated porous media. The surface thermodynamics was characterized by contact-angle measurement and the wicking method, which was related to surface free energies of Lifshitz,van der Waals interaction, Lewis acid,base interaction, and electrostatic interaction between the bacteria and the medium matrix. Transport of three different strains of bacteria present at three physiological states was measured in columns of silica gel and sand from the Canadian River Alluvium (Norman, OK, USA). Microorganisms in stationary state had the highest deposit on solid matrix, compared with logarithmic and decay states. The deposition correlated with the total surface free energy (,G132TOT) and the differences in ,G132TOT were mainly controlled by the Lewis acid,base interaction. Infrared spectroscopy showed that the increased deposition correlated with an increase in the hydrogen-bonding functional groups on the cell surfaces. [source]

    The accuracy of regulatory cost estimates: a study of the London congestion charging scheme

    Chris Sherrington
    Abstract This paper considers the accuracy of regulatory cost estimates using the London congestion charging scheme as a case study. In common with other regulations, ex ante estimates of the direct costs of the scheme were produced by the regulator, Transport for London. Reviews of a number of environmental and industrial regulations have shown that ex ante costs tend to exceed the ex post (or outturn) costs. This study finds that while Transport for London moderately overestimated the total costs of the scheme (by 16%) there was a significant overestimate of chargepayer compliance costs (by 64%). The main reasons for this were greater than expected reductions in traffic and unanticipated technological innovation. As the compliance cost is essentially the cost of transacting payment of the charge, these results have wider implications for other similar regulations. One example is the proposed national road user charging in the UK, where it could reasonably be expected that the ex post cost of compliance will again be lower than the ex ante estimate, and that compliance costs will continue to reduce over time. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment. [source]

    Transport and environment: policy directions for europe

    Robert Tinch
    Transport externalities are among the most important environmental problems affecting quality of life in Europe. Forecasts suggest that past environmental improvements may now be rolled back by traffic growth, and current traffic trends are not sustainable. The theory of environmental policy proposes pricing external costs at their marginal social costs as one solution. Although full marginal social cost pricing is impracticable, advances in tolling technology and environmental valuation mean that it is now a viable option to approximate such charging. There are signs that the European Commission and other bodies are starting to favour pricing over regulatory instruments. However, often overlooked is the potential for non-convexities in the transport sector or between transport and the rest of the economy. For example it may be that small increases in resources for public transport would not result in welfare gains, whereas large increases would. Non-convexities would mean that market forces under marginal social cost pricing might lead away from the optimal transport system. This is one reason why pricing instruments cannot in themselves be a panacea for transport externalities or bring about a sustainable transport system. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment [source]

    Mechanisms affecting the dissolution of nonaqueous phase liquids into the aqueous phase in slow-stirring batch systems

    Mathias Schluep
    Abstract Understanding the kinetics of the exchange processes between nonaqueous phase liquids (NALs) and water is important in predicting the fate of anthropogenic compounds such as petroleum hydrocarbons, i.e., benzene, toluene, ethylbenzene, and xylene (BTEX) as well as polynuclear aromatic hydrocarbons (PAHs). Exchange processes occurring in the environment resemble the experimental setup of the slow-stirring method (SSM) designed to determine solubilities and octanol-water partition coefficients. Data obtained from SSM experiments for diesel fuel compounds are interpreted by a linear transfer model that is characterized by an aqueous molecular boundary layer and the water/NAPL equilibrium partition coefficient. For the chosen experimental setup, the boundary layer thickness is 2.42 × 10,2 cm. Typical equilibration times lie between 1 and 2 d. Due to the temperature dependence of the aqueous diffusivity, this time increases with decreasing temperature. Transport within the NAPL phase can slow down the exchange process for the more water-soluble compounds (e.g., benzene) provided that the stirring rate exceeds a critical value. [source]

    Binding of Oxovanadium(IV) to Tripeptides Containing Histidine and Cysteine Residues and Its Biological Implication in the Transport of Vanadium and Insulin-Mimetic Compounds

    Eugenio Garribba
    Abstract The complexation of VIVO ion with three tripeptides of biological importance containing L -histidine or L -cysteine (HisGlyGly, GlyGlyHis and GlyGlyCys) has been studied. This study was performed in aqueous solution by the combined application of potentiometric and spectroscopic (electronic absorption and EPR) techniques. The results indicate that these oligopeptides, if a ligand-to-metal molar ratio of 10 or 15 is used, can keep VIVO ion in solution until the deprotonation of the amide group with the donor set (NH2, CO, Nimax) for HisGlyGly or (COO,, CO) for GlyGlyHis and GlyGlyCys. In all the systems, at pH values around neutrality, a VOLH,2 species is formed with an (NH2, N,, N,, COO,) donor set for HisGlyGly, (NH2, N,, N,, Nim) for GlyGlyHis and (NH2, N,,N,, S,) for GlyGlyCys. These species, and those with onedeprotonated amide group coordinated to the VIVO ion, can be detected by EPR spectroscopy. The N,(amide) contribution to the hyperfine coupling constant along the z axis, Az, depends on the total charge of the donor atoms in the equatorial plane. The participation of albumin in the transport of vanadium and insulin-mimetic VIVO compounds is reconsidered based on these results. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    Ultra-Fast Atomic Transport in Severely Deformed Materials,A Pathway to Applications?,

    Sergiy Divinski
    Abstract Severe plastic deformation of pure Cu and Cu-rich alloys was found to create a hierarchical combination of fast and ultra-fast diffusion paths ranging from non-equilibrium grain boundaries to non-equilibrium triple junctions, vacancy clusters, nano- and micro-pores, and finally to general high-angle grain boundaries. Under certain conditions, a percolating network of porosity can be introduced in the ultra-fine grained materials by a proper mechanical and thermal treatment. This network may offer promising opportunities for creating materials with tailor-made properties, including combinations of improved mechanical performance with a possibility of self repair using "vascular structures" for atom transport. Applications in such areas as drug eluting bioimplants and lead or polymer eluting materials for reduction of friction based on impregnation of porosity networks with these agents are also envisaged. [source]

    Heat Transport in Closed Cell Aluminum Foams: Application Notes,

    Jaime Lázaro
    Heat transport equations have been used to solve, by implementing the Finite Element Method (FEM), three different cases representative of the aluminium foams life: the production process (solidification in the molten state), post-production (water quenching heat treatments) and applications (fire barriers). [source]

    Quantitative Removal of Mercury(II) from Water Through Bulk Liquid Membranes by Lipophilic Polyamines

    Nicoletta Spreti
    Abstract Transport of mercury(II) and copper(II) ions through bulk liquid membranes has been studied, the former because of its toxicity and wide distribution in the environment, the latter for comparative purposes. The abilities of two carriers, the known N,N, -bis[2-(hexadecylamino)ethyl]- N,N, -bis(hydroxyethyl)ethylenediamine (bis-HE16ED) and the new N,N,-bis(p -octyloxybenzyl)-3,6-dioxaoctane-1,8-diamine (bis- pODODA), to complex and transport the selected metal ions are reported. Bis-HE16ED is a good carrier for Cu2+ ions, but the high stability of the carrier/Hg2+ ion complex in the membrane results in a lack of its transport. On the other hand, the new carrier displays a very high efficiency in Hg2+ ion transport, effecting quantitative transfer of the metal ion into the receiving phase within 24 h, despite its chelating region being only slightly different from that in bis-HE16ED. The ability of bis- pODODA to transport 100,% of Hg2+ efficiently in consecutive cycles is also reported. This result provides a basis for future development of a decontamination process based on a carrier-mediated transport system. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Carrier-Mediated Transport of Toxic Heavy Metal Ions in Bulk Liquid Membranes

    Lucia Brinchi
    Abstract Transport through a dichloromethane liquid membrane has been studied to investigate the ability of 1,1,7,7-tetraethyl-4-tetradecyldiethylenetriamine (TE14DT), previously tested for the transport of copper, to act as a carrier for toxic heavy metal ions such as Cd2+, Pb2+ and Hg2+. The carrier displayed a remarkable capability to extract all the metal ions from the source to the organic phases but only cadmium was efficiently transported across the membrane. The experimental conditions optimised for the transport of copper are inadequate for lead and mercury. In fact, the inefficacy of their transport could be due, as regards lead, to the slow diffusion of the complex through the membrane, while mercury remained in the organic phase because of the high stability of the mercury-carrier complex. Selectivity tests using binary mixtures of the metal ions showed TE14DT's capability to transport copper or cadmium also in the presence of lead in the source phase. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Modelling of colloid leaching from unsaturated, aggregated soil

    M. Laegdsmand
    Summary The migration of colloids in soils can enhance the leaching of strongly sorbing contaminants. We present a model for the simulation of colloid leaching from unsaturated, aggregated soil media under stationary flow. Transport in the intra-aggregate pores is simulated by convection,dispersion, and transport in the interaggregate pores, and a stagnant layer of water surrounding the aggregates, is simulated by diffusion. The model describes the release of colloids from soil aggregates, sorption and desorption processes at the air,water interfaces, and flocculation and subsequent straining from the flowing water. All three processes were simulated as functions of ionic strength. Transport of ions in intra-aggregate pores was simulated by Fickian diffusion. The model was calibrated against experimental results of colloid leaching from columns packed with natural soil aggregates. The aggregates were of two soils differing in organic matter content. On each soil a single calibrated parameter set could describe the experiments with the three ionic strengths. The parameters for release of colloids from the aggregate surface and the sorption properties of the air,water interface were different for the two soils. The key parameters for leaching were the thickness of the stagnant layer of water surrounding the aggregates, the mechanical dispersion, the maximum concentration of colloids at the surface of the aggregates, the sorption capacity and rate coefficient of the colloids at the air,water interface, and the colloid diffusion coefficient. Simulations were also done with two additional irrigation intensities at one ionic strength. Simulated leaching was greater than measured leaching at both irrigation intensities, but the diffusion-controlled release of colloids from the aggregates was simulated correctly. [source]

    Kinetics of Thyroxine (T4) and Triiodothyronine (T3) Transport in the Isolated Rat Heart

    Mirko A. Rosic
    The dynamics and kinetics of thyroid hormone transport in the isolated rat heart were examined using the modified unidirectional paired tracer dilution method. The uptake of 125I-thyroxine (125I-T4) and 125I-triiodothyronine (125I-T3) from the extracellular space into heart cells was measured relative to the extracellular space marker 3H-mannitol. The thyroid hormone maximal uptake was 54.4% for 125I-T4 and 52.15% for 125I-T3. The thyroid hormone net uptake was 25.69% for 125I-T4 and 25.49% for 125I-T3. Backflux from the intracellular space was 53.17% for 125I-T4 and 61.59% for 125I-T3. In the presence of unlabelled thyroid hormones, 125I-T4 and 125I-T3 maximal uptakes were reduced from 10.1 to 59.74% and from 34.6 to 65.3%, respectively, depending on the concentration of the unlabelled hormone, suggesting a saturable mechanism of the thyroid hormone uptake by the heart cells, with Km(T4)= 105.46 ,M and the maximal rate of 125I-thyroid hormone flux from the extracellular space to heart cells (Vmax(T4)) = 177.84 nM min,1 for 125I-T4 uptake, and Km(T3)= 80.0 ,M and Vmax(T3)= 118.5 nM min,1 for 125I-T3 uptake. [source]

    Epidermal Growth Factor Regulates Amino Acid Transport in Chick Embryo Hepatocytes via Protein Kinase C

    Maria Marino
    System A-mediated amino acid transport, activation of different steps of signal transduction and involvement of different isoforms of protein kinase C (PKC) have been investigated in chick embryo hepatocytes after epidermal growth factor (EGF) stimulation. EGF rapidly (10 min) increased the rate of aminoisobutyric acid (AIB) uptake in chick embryo hepatocytes freshly isolated on the 19th day of embryonic life, while no change was detectable at other embryonal stages. The growth factor stimulation was abolished by PKC and tyrosine kinase inhibitors and was mimicked by 4-phorbol-12-myristate-13-acetate, dimethyl-2 (PMA). EGF treatment did not modify the phosphorylation of the , isoform of phospholipase C (PLC-,), and inositol trisphosphate (IP3) and intracellular calcium levels, but it induced an increase in PKC activity. Our data show that EGF regulates amino acid uptake, via PKC and without PLC-, activation, only in the last period of chick embryo hepatocyte development. The effects of growth factor on PKC activity suggest the involvement of PKC-, and -, isoforms in EGF modulation of amino acid transport. [source]

    Nanomotors: Magnetic Control of Tubular Catalytic Microbots for the Transport, Assembly, and Delivery of Micro-objects (Adv. Funct.

    S. Sanchez, Y. F. Mei, and co-workers present the concept of a microfactory on page 2430, where micro-objects are mixed together with synthetic microbots in a fluid and fuel is added in order to power them, as shown in the image. The motion of these microbots is remotely controlled by magnetic field that is an essential requirement for specialized tasks such as transport and delivery of microscale loads. [source]