Science.gov

Sample records for iron transport systems

  1. Bacterial ferrous iron transport: the Feo system.

    PubMed

    Lau, Cheryl K Y; Krewulak, Karla D; Vogel, Hans J

    2016-03-01

    To maintain iron homeostasis within the cell, bacteria have evolved various types of iron acquisition systems. Ferric iron (Fe(3+)) is the dominant species in an oxygenated environment, while ferrous iron (Fe(2+)) is more abundant under anaerobic conditions or at low pH. For organisms that must combat oxygen limitation for their everyday survival, pathways for the uptake of ferrous iron are essential. Several bacterial ferrous iron transport systems have been described; however, only the Feo system appears to be widely distributed and is exclusively dedicated to the transport of iron. In recent years, many studies have explored the role of the FeoB and FeoA proteins in ferrous iron transport and their contribution toward bacterial virulence. The three-dimensional structures for the Feo proteins have recently been determined and provide insight into the molecular details of the transport system. A highly select group of bacteria also express the FeoC protein from the same operon. This review will provide a comprehensive look at the structural and functional aspects of the Feo system. In addition, bioinformatics analyses of the feo operon and the Feo proteins have been performed to complement our understanding of this ubiquitous bacterial uptake system, providing a new outlook for future studies.

  2. Genetics and environmental regulation of Shigella iron transport systems.

    PubMed

    Wyckoff, Elizabeth E; Boulette, Megan L; Payne, Shelley M

    2009-02-01

    Shigella spp. have transport systems for both ferric and ferrous iron. The iron can be taken up as free iron or complexed to a variety of carriers. All Shigella species have both the Feo and Sit systems for acquisition of ferrous iron, and all have at least one siderophore-mediated system for transport of ferric iron. Several of the transport systems, including Sit, Iuc/IutA (aerobactin synthesis and transport), Fec (ferric di-citrate uptake), and Shu (heme transport) are encoded within pathogenicity islands. The presence and the genomic locations of these islands vary considerably among the Shigella species, and even between isolates of the same species. The expression of the iron transport systems is influenced by the concentration of iron and by environmental conditions including the level of oxygen. ArcA and FNR regulate iron transport gene expression as a function of oxygen tension, with the sit and iuc promoters being highly expressed in aerobic conditions, while the feo ferrous iron transporter promoter is most active under anaerobic conditions. The effects of oxygen are also seen in infection of cultured cells by Shigella flexneri; the Sit and Iuc systems support plaque formation under aerobic conditions, whereas Feo allows plaque formation anaerobically.

  3. Regulation of iron transport systems in Enterobacteriaceae in response to oxygen and iron availability.

    PubMed

    Carpenter, Chandra; Payne, Shelley M

    2014-04-01

    Iron is an essential nutrient for most bacteria. Depending on the oxygen available in the surrounding environment, iron is found in two distinct forms: ferrous (Fe(II)) or ferric (Fe(III)). Bacteria utilize different transport systems for the uptake of the two different forms of iron. In oxic growth conditions, iron is found in its insoluble, ferric form, and in anoxic growth conditions iron is found in its soluble, ferrous form. Enterobacteriaceae have adapted to transporting the two forms of iron by utilizing the global, oxygen-sensing regulators, ArcA and Fnr to regulate iron transport genes in response to oxygen.

  4. Characterization of ferric and ferrous iron transport systems in Vibrio cholerae.

    PubMed

    Wyckoff, Elizabeth E; Mey, Alexandra R; Leimbach, Andreas; Fisher, Carolyn F; Payne, Shelley M

    2006-09-01

    Vibrio cholerae has multiple iron acquisition systems, including TonB-dependent transport of heme and of the catechol siderophore vibriobactin. Strains defective in both of these systems grow well in laboratory media and in the infant mouse intestine, indicating the presence of additional iron acquisition systems. Previously uncharacterized potential iron transport systems, including a homologue of the ferrous transporter Feo and a periplasmic binding protein-dependent ATP binding cassette (ABC) transport system, termed Fbp, were identified in the V. cholerae genome sequence. Clones encoding either the Feo or the Fbp system exhibited characteristics of iron transporters: both repressed the expression of lacZ cloned under the control of a Fur-regulated promoter in Escherichia coli and also conferred growth on a Shigella flexneri mutant that has a severe defect in iron transport. Two other ABC transporters were also evaluated but were negative by these assays. Transport of radioactive iron by the Feo system into the S. flexneri iron transport mutant was stimulated by the reducing agent ascorbate, consistent with Feo functioning as a ferrous transporter. Conversely, ascorbate inhibited transport by the Fbp system, suggesting that it transports ferric iron. The growth of V. cholerae strains carrying mutations in one or more of the potential iron transport genes indicated that both Feo and Fbp contribute to iron acquisition. However, a mutant defective in the vibriobactin, Fbp, and Feo systems was not attenuated in a suckling mouse model, suggesting that at least one other iron transport system can be used in vivo.

  5. Pharmacology of Iron Transport

    PubMed Central

    Byrne, Shaina L.; Krishnamurthy, Divya; Wessling-Resnick, Marianne

    2013-01-01

    Elucidating the molecular basis for the regulation of iron uptake, storage, and distribution is necessary to understand iron homeostasis. Pharmacological tools are emerging to identify and distinguish among different iron transport pathways. Stimulatory or inhibitory small molecules with effects on iron uptake can help characterize the mechanistic elements of iron transport and the roles of the transporters involved in these processes. In particular, iron chelators can serve as potential pharmacological tools to alleviate diseases of iron overload. This review focuses on the pharmacology of iron transport, introducing iron transport membrane proteins and known inhibitors. PMID:23020294

  6. OPT3 Is a Phloem-Specific Iron Transporter That Is Essential for Systemic Iron Signaling and Redistribution of Iron and Cadmium in Arabidopsis[W][OPEN

    PubMed Central

    Zhai, Zhiyang; Gayomba, Sheena R.; Jung, Ha-il; Vimalakumari, Nanditha K.; Piñeros, Miguel; Craft, Eric; Rutzke, Michael A.; Danku, John; Lahner, Brett; Punshon, Tracy; Guerinot, Mary Lou; Salt, David E.; Kochian, Leon V.; Vatamaniuk, Olena K.

    2014-01-01

    Iron is essential for both plant growth and human health and nutrition. Knowledge of the signaling mechanisms that communicate iron demand from shoots to roots to regulate iron uptake as well as the transport systems mediating iron partitioning into edible plant tissues is critical for the development of crop biofortification strategies. Here, we report that OPT3, previously classified as an oligopeptide transporter, is a plasma membrane transporter capable of transporting transition ions in vitro. Studies in Arabidopsis thaliana show that OPT3 loads iron into the phloem, facilitates iron recirculation from the xylem to the phloem, and regulates both shoot-to-root iron signaling and iron redistribution from mature to developing tissues. We also uncovered an aspect of crosstalk between iron homeostasis and cadmium partitioning that is mediated by OPT3. Together, these discoveries provide promising avenues for targeted strategies directed at increasing iron while decreasing cadmium density in the edible portions of crops and improving agricultural productivity in iron deficient soils. PMID:24867923

  7. Regulation of the transferrin-independent iron transport system in cultured cells.

    PubMed

    Kaplan, J; Jordan, I; Sturrock, A

    1991-02-15

    Mammalian cells accumulate iron via the binding of transferrin to high affinity surface receptors, or through a transferrin-independent pathway which involves the uptake of iron-organic anion chelates by a membrane-based transport system. Previously we determined that the transferrin-independent transport system was present on a wide variety of cultured cells (Sturrock, A., Alexander, J., Lamb, J., Craven, C. M., and Kaplan, J. (1990) J. Biol. Chem. 265, 3139-3145). In this communication we demonstrate that the transferrin-independent iron uptake system is regulated differently than the transferrin-mediated pathway. The activity of the transferrin-independent system was unaffected by changes in cellular growth rate, induction of DNA synthesis and cell division, or depletion of cellular iron. Exposure of cells to ferric or ferrous iron, however, resulted in a time-dependent increase in transport activity, due to a change in Vmax with no change in Km. Increased transport activity was seen in a variety of cultured cell types, occurred in the presence of cycloheximide, and persisted for hours after removal of iron. The ability of other transition metals to induce changes in transport, or to compete with iron for accumulation by the transferrin-independent uptake system, was critically dependent on the composition of the media in which the cells were incubated. Metals such as Cu2+ or Zn2+, but not Cd2+ or Mn2+, when dissolved in a balanced salt solution buffered with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, induced changes in the transferrin-independent iron transport system. The same metals which induced changes in transport were ineffective in media containing amino acids, ascorbate, or N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine. The Vmax of the transferrin-independent iron transport system was also elevated by increases in intracellular Ca2+. The effect of iron on transport activity, however, did not result from an iron-induced release of

  8. Chemical interference with iron transport systems to suppress bacterial growth of Streptococcus pneumoniae.

    PubMed

    Yang, Xiao-Yan; Sun, Bin; Zhang, Liang; Li, Nan; Han, Junlong; Zhang, Jing; Sun, Xuesong; He, Qing-Yu

    2014-01-01

    Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics.

  9. Chemical Interference with Iron Transport Systems to Suppress Bacterial Growth of Streptococcus pneumoniae

    PubMed Central

    Zhang, Liang; Li, Nan; Han, Junlong; Zhang, Jing; Sun, Xuesong; He, Qing-Yu

    2014-01-01

    Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics. PMID:25170896

  10. Cellular iron transport.

    PubMed

    Garrick, Michael D; Garrick, Laura M

    2009-05-01

    Iron has a split personality as an essential nutrient that also has the potential to generate reactive oxygen species. We discuss how different cell types within specific tissues manage this schizophrenia. The emphasis in enterocytes is on regulating the body's supply of iron by regulating transport into the blood stream. In developing red blood cells, adaptations in transport manage the body's highest flux of iron. Hepatocytes buffer the body's stock of iron. Macrophage recycle the iron from effete red cells among other iron management tasks. Pneumocytes provide a barrier to prevent illicit entry that, when at risk of breaching, leads to a need to handle the dangers in a fashion essentially shared with macrophage. We also discuss or introduce cell types including renal cells, neurons, other brain cells, and more where our ignorance, currently still vast, needs to be removed by future research. PMID:19344751

  11. The Vibrio cholerae VctPDGC system transports catechol siderophores and a siderophore-free iron ligand.

    PubMed

    Wyckoff, Elizabeth E; Payne, Shelley M

    2011-09-01

    Vibrio cholerae, the causative agent of cholera, has an absolute requirement for iron. It transports the catechol siderophores vibriobactin, which it synthesizes and secretes, and enterobactin. These siderophores are transported across the inner membrane by one of two periplasmic binding protein-dependent ABC transporters, VctPDGC or ViuPDGC. We show here that one of these inner membrane transport systems, VctPDGC, also promotes iron acquisition in the absence of siderophores. Plasmids carrying the vctPDGC genes stimulated growth in both rich and minimal media of a Shigella flexneri mutant that produces no siderophores. vctPDGC also stimulated the growth of an Escherichia coli enterobactin biosynthetic mutant in low iron medium, and this effect did not require feoB, tonB or aroB. A tyrosine to phenylalanine substitution in the periplasmic binding protein VctP did not alter enterobactin transport, but eliminated growth stimulation in the absence of a siderophore. These data suggest that the VctPDGC system has the capacity to transport both catechol siderophores and a siderophore-free iron ligand. We also show that VctPDGC is the previously unidentified siderophore-independent iron transporter in V. cholerae, and this appears to complete the list of iron transport systems in V. cholerae.

  12. Comparative Genomics of Iron-Transporting Systems in Bacillus cereus Strains and Impact of Iron Sources on Growth and Biofilm Formation.

    PubMed

    Hayrapetyan, Hasmik; Siezen, Roland; Abee, Tjakko; Nierop Groot, Masja

    2016-01-01

    Iron is an important element for bacterial viability, however it is not readily available in most environments. We studied the ability of 20 undomesticated food isolates of Bacillus cereus and two reference strains for capacity to use different (complex) iron sources for growth and biofilm formation. Studies were performed in media containing the iron scavenger 2,2-Bipyridine. Transcriptome analysis using B. cereus ATCC 10987 indeed showed upregulation of predicted iron transporters in the presence of 2,2-Bipyridine, confirming that iron was depleted upon its addition. Next, the impact of iron sources on growth performance of the 22 strains was assessed and correlations between growth stimulation and presence of putative iron transporter systems in the genome sequences were analyzed. All 22 strains effectively used Fe citrate and FeCl3 for growth, and possessed genes for biosynthesis of the siderophore bacillibactin, whereas seven strains lacked genes for synthesis of petrobactin. Hemoglobin could be used by all strains with the exception of one strain that lacked functional petrobactin and IlsA systems. Hemin could be used by the majority of the tested strains (19 of 22). Notably, transferrin, ferritin, and lactoferrin were not commonly used by B. cereus for growth, as these iron sources could be used by 6, 3, and 2 strains, respectively. Furthermore, biofilm formation was found to be affected by the type of iron source used, including stimulation of biofilms at liquid-air interphase (FeCl3 and Fe citrate) and formation of submerged type biofilms (hemin and lactoferrin). Our results show strain variability in the genome-encoded repertoire of iron-transporting systems and differences in efficacy to use complex iron sources for growth and biofilm formation. These features may affect B. cereus survival and persistence in specific niches.

  13. Comparative Genomics of Iron-Transporting Systems in Bacillus cereus Strains and Impact of Iron Sources on Growth and Biofilm Formation

    PubMed Central

    Hayrapetyan, Hasmik; Siezen, Roland; Abee, Tjakko; Nierop Groot, Masja

    2016-01-01

    Iron is an important element for bacterial viability, however it is not readily available in most environments. We studied the ability of 20 undomesticated food isolates of Bacillus cereus and two reference strains for capacity to use different (complex) iron sources for growth and biofilm formation. Studies were performed in media containing the iron scavenger 2,2-Bipyridine. Transcriptome analysis using B. cereus ATCC 10987 indeed showed upregulation of predicted iron transporters in the presence of 2,2-Bipyridine, confirming that iron was depleted upon its addition. Next, the impact of iron sources on growth performance of the 22 strains was assessed and correlations between growth stimulation and presence of putative iron transporter systems in the genome sequences were analyzed. All 22 strains effectively used Fe citrate and FeCl3 for growth, and possessed genes for biosynthesis of the siderophore bacillibactin, whereas seven strains lacked genes for synthesis of petrobactin. Hemoglobin could be used by all strains with the exception of one strain that lacked functional petrobactin and IlsA systems. Hemin could be used by the majority of the tested strains (19 of 22). Notably, transferrin, ferritin, and lactoferrin were not commonly used by B. cereus for growth, as these iron sources could be used by 6, 3, and 2 strains, respectively. Furthermore, biofilm formation was found to be affected by the type of iron source used, including stimulation of biofilms at liquid-air interphase (FeCl3 and Fe citrate) and formation of submerged type biofilms (hemin and lactoferrin). Our results show strain variability in the genome-encoded repertoire of iron-transporting systems and differences in efficacy to use complex iron sources for growth and biofilm formation. These features may affect B. cereus survival and persistence in specific niches. PMID:27375568

  14. Iron transport in Parkinson's disease.

    PubMed

    Hirsch, E C

    2009-12-01

    Dopaminergic cell death in the substantia nigra (SN) is central to Parkinson's disease (PD) but the neurodegenerative mechanisms have not been completely elucidated. Iron accumulation in dopaminergic neurons and glial cells in the SN of PD patients may contribute to the generation of oxidative stress, protein aggregation and neuronal death. However, the mechanisms involved in iron accumulation remain unclear. In previous studies we excluded a role of transferrin and its receptor in iron accumulation while we showed that lactoferrin receptors were overexpressed in blood vessels and dopaminergic neurons in Parkinson's disease. We recently also described an increase in the expression of the divalent metal transporter 1 (DMT1/Nramp2/Slc11a2) in the SN of PD patients. Using the PD animal model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication in mice, we showed that DMT1 expression increased in the ventral mesencephalon of intoxicated animals, concomitant with iron accumulation, oxidative stress and dopaminergic cell loss. A mutation in DMT1 that impairs iron transport protected rodents against parkinsonism-inducing neurotoxins MPTP and 6-hydroxydopamine (6-OHDA). This study supports a critical role for DMT1 in iron-mediated neurodegeneration in PD. PMID:20082992

  15. Vibrio Iron Transport: Evolutionary Adaptation to Life in Multiple Environments.

    PubMed

    Payne, Shelley M; Mey, Alexandra R; Wyckoff, Elizabeth E

    2016-03-01

    Iron is an essential element for Vibrio spp., but the acquisition of iron is complicated by its tendency to form insoluble ferric complexes in nature and its association with high-affinity iron-binding proteins in the host. Vibrios occupy a variety of different niches, and each of these niches presents particular challenges for acquiring sufficient iron. Vibrio species have evolved a wide array of iron transport systems that allow the bacteria to compete for this essential element in each of its habitats. These systems include the secretion and uptake of high-affinity iron-binding compounds (siderophores) as well as transport systems for iron bound to host complexes. Transporters for ferric and ferrous iron not complexed to siderophores are also common to Vibrio species. Some of the genes encoding these systems show evidence of horizontal transmission, and the ability to acquire and incorporate additional iron transport systems may have allowed Vibrio species to more rapidly adapt to new environmental niches. While too little iron prevents growth of the bacteria, too much can be lethal. The appropriate balance is maintained in vibrios through complex regulatory networks involving transcriptional repressors and activators and small RNAs (sRNAs) that act posttranscriptionally. Examination of the number and variety of iron transport systems found in Vibrio spp. offers insights into how this group of bacteria has adapted to such a wide range of habitats.

  16. Mining iron: iron uptake and transport in plants.

    PubMed

    Kim, Sun A; Guerinot, Mary Lou

    2007-05-25

    Iron uptake in plants is highly regulated in order to supply amounts sufficient for optimal growth while preventing excess accumulation. In response to iron deficiency, plants induce either reduction-based or chelation-based mechanisms to enhance iron uptake from the soil. Genes involved in each mechanism have been identified from various model plants including Arabidopsis and rice. Iron transport within plants is also tightly controlled. New information has emerged on transporters that play a role in xylem loading and phloem loading/unloading of iron, and on the iron chelators involved in iron homeostasis. Some of the components regulating iron deficiency responses also have been elucidated, demonstrating that iron dependent gene regulation occurs at both the transcriptional and post-transcriptional levels. PMID:17485078

  17. Iron absorption and transport-an update.

    PubMed

    Conrad, M E; Umbreit, J N

    2000-08-01

    Iron is vital for all living organisms. However, excess iron is hazardous because it produces free radical formation. Therefore, iron absorption is carefully regulated to maintain an equilibrium between absorption and body loss of iron. In countries where heme is a significant part of the diet, most body iron is derived from dietary heme iron because heme binds few of the luminal intestinal iron chelators that inhibit absorption of non-heme iron. Uptake of luminal heme into enterocytes occurs as a metalloporphyrin. Intracellularly, iron is released from heme by heme oxygenase so that iron leaves the enterocyte to enter the plasma as non-heme iron. Ferric iron is absorbed via a beta(3) integrin and mobilferrin (IMP) pathway that is not shared with other nutritional metals. Ferrous iron uptake is facilitated by DMT-1 (Nramp-2, DCT-1) in a pathway shared with manganese. Other proteins were recently described which are believed to play a role in iron absorption. SFT (Stimulator of Iron Transport) is postulated to facilitate both ferric and ferrous iron uptake, and Hephaestin is thought to be important in transfer of iron from enterocytes into the plasma. The iron concentration within enterocytes reflects the total body iron and either upregulates or satiates iron-binding sites on regulatory proteins. Enterocytes of hemochromatotics are iron-depleted similarly to the absorptive cells of iron-deficient subjects. Iron depletion, hemolysis, and hypoxia each can stimulate iron absorption. In non-intestinal cells most iron uptake occurs via either the classical clathrin-coated pathway utilizing transferrin receptors or the poorly defined transferrin receptor independent pathway. Non-intestinal cells possess the IMP and DMT-1 pathways though their role in the absence of iron overload is unclear. This suggests that these pathways have intracellular functions in addition to facilitating iron uptake.

  18. OPT3 is a phloem-specific iron transporter that is essential for systemic iron signaling and redistribution of iron and cadmium in arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron is essential for both plant growth and human health and nutrition. Cadmium, on the other hand, is a non-essential and highly toxic element that competes with iron for uptake and partitioning in plant tissues, posing a threat to crop productivity and human health. Knowledge of signaling mechanis...

  19. Coordination Chemistry of Microbial Iron Transport.

    PubMed

    Raymond, Kenneth N; Allred, Benjamin E; Sia, Allyson K

    2015-09-15

    with the characterization of what are now called siderocalins. Initially found as a protein of the human innate immune system, these proteins bind both ferric and apo-siderophores to inactivate the siderophore transport system and hence deny iron to an invading pathogenic microbe. Siderocalins also can play a role in iron transport of the host, particularly in the early stages of fetal development. Finally, it is speculated that the molecular targets of siderocalins in different species differ based on the siderophore structures of the most important bacterial pathogens of those species.

  20. Coordination Chemistry of Microbial Iron Transport

    PubMed Central

    2016-01-01

    has emerged with the characterization of what are now called siderocalins. Initially found as a protein of the human innate immune system, these proteins bind both ferric and apo-siderophores to inactivate the siderophore transport system and hence deny iron to an invading pathogenic microbe. Siderocalins also can play a role in iron transport of the host, particularly in the early stages of fetal development. Finally, it is speculated that the molecular targets of siderocalins in different species differ based on the siderophore structures of the most important bacterial pathogens of those species. PMID:26332443

  1. Iron uptake and transport across physiological barriers.

    PubMed

    Duck, Kari A; Connor, James R

    2016-08-01

    Iron is an essential element for human development. It is a major requirement for cellular processes such as oxygen transport, energy metabolism, neurotransmitter synthesis, and myelin synthesis. Despite its crucial role in these processes, iron in the ferric form can also produce toxic reactive oxygen species. The duality of iron's function highlights the importance of maintaining a strict balance of iron levels in the body. As a result, organisms have developed elegant mechanisms of iron uptake, transport, and storage. This review will focus on the mechanisms that have evolved at physiological barriers, such as the intestine, the placenta, and the blood-brain barrier (BBB), where iron must be transported. Much has been written about the processes for iron transport across the intestine and the placenta, but less is known about iron transport mechanisms at the BBB. In this review, we compare the established pathways at the intestine and the placenta as well as describe what is currently known about iron transport at the BBB and how brain iron uptake correlates with processes at these other physiological barriers. PMID:27457588

  2. The placenta: the forgotten essential organ of iron transport.

    PubMed

    Cao, Chang; Fleming, Mark D

    2016-07-01

    Optimal iron nutrition in utero is essential for development of the fetus and helps establish birth iron stores adequate to sustain growth in early infancy. In species with hemochorial placentas, such as humans and rodents, iron in the maternal circulation is transferred to the fetus by directly contacting placental syncytiotrophoblasts. Early kinetic studies provided valuable data on the initial uptake of maternal transferrin, an iron-binding protein, by the placenta. However, the remaining steps of iron trafficking across syncytiotrophoblasts and through the fetal endothelium into the fetal blood remain poorly characterized. Over the last 20 years, identification of transmembrane iron transporters and the iron regulatory hormone hepcidin has greatly expanded the knowledge of cellular iron transport and its regulation by systemic iron status. In addition, emerging human and animal data demonstrating comprised fetal iron stores in severe maternal iron deficiency challenge the classic dogma of exclusive fetal control over the transfer process and indicate that maternal and local signals may play a role in regulating this process. This review compiles current data on the kinetic, molecular, and regulatory aspects of placental iron transport and considers new questions and knowledge gaps raised by these advances. PMID:27261274

  3. Ferrous iron transport in Streptococcus mutans

    SciTech Connect

    Evans, S.L.; Arcenaeux, J.E.L.; Byers, B.R.; Martin, M.E.; Aranha, H.

    1986-12-01

    Radioiron uptake from /sup 59/FeCl/sub 3/ by Streptococcus mutans OMZ176 was increased by anaerobiosis, sodium ascorbate, and phenazine methosulfate (PMS), although there was a 10-min lag before PMS stimulation was evident. The reductant ascorbate may have provided ferrous iron. The PMS was reduced by the cells, and the reduced PMS then may have generated ferrous iron for transport; reduced PMS also may have depleted dissolved oxygen. It was concluded that S. mutans transports only ferrous iron, utilizing reductants furnished by glucose metabolism to reduce iron prior to its uptake.

  4. Iron transport in Mycobacterium smegmatis: uptake of iron from ferric citrate

    SciTech Connect

    Messenger, A.J.M.; Ratledge, C.

    1982-01-01

    In mycobacterial growth medium 40 to 400 ..mu..M citrate was required to solubilize 2 ..mu..M /sup 55/Fe. This solubilized /sup 55/Fe was taken up into both iron-deficient and iron-sufficient washed cell suspensions of Mycobacterium smegmatis and Mycobacterium bovis BCG. Although the /sup 55/Fe was taken up into the cell, the citrate was not. The uptake system with M. smegmatis was not inhibited by electron transport inhibitors, uncouplers of oxidative phosphorylation, or thiol reagents and was saturable with iron at approximately 35 ..mu..M. The system was independent of the iron transport systems already known to exist in M. smegmatis: i.e., the two exochelin routes of assimilation as well as the mycobactin-salicylate system. It was not induced by the presence of 400 ..mu..M citrate in the growth medium, nor did the presence of citrate in the medium affect the production of either exochelin or mycobactin.

  5. Dinitrosyl iron complexes and S-nitrosothiols are two possible forms for stabilization and transport of nitric oxide in biological systems.

    PubMed

    Vanin, A F

    1998-07-01

    The physicochemical properties, mechanisms of synthesis and decomposition of dinitrosyl iron complexes (DNICs) with thiol-containing ligands and of S-nitrosothiols (RS-NO), and the potential role of these compounds in storage and transport of NO in biological systems are reviewed. Special attention is given to the phenomenon of mutual transformation of DNIC and RS-NO catalyzed by Fe2+. Each Fe2+ binds two neutral NO molecules in the DNICs, catalyzes their mutual oxidation--reduction with formation of nitrous oxide and nitrosonium ions appearing in the DNICs. These ions S-nitrosate thiol-compounds with RS-NO formation. Fe2+ binds two RS-NO molecules and catalyzes their mutual oxidation--reduction followed by decomposition of the resulting molecules. Mutual conversion of DNICs and RS-NO regulated by iron, thiol, and NO levels is suggested to provide NO transport in cells and tissues. PMID:9721330

  6. Coordinated transporter activity shapes high-affinity iron acquisition in cyanobacteria

    PubMed Central

    Kranzler, Chana; Lis, Hagar; Finkel, Omri M; Schmetterer, Georg; Shaked, Yeala; Keren, Nir

    2014-01-01

    Iron bioavailability limits biological activity in many aquatic and terrestrial environments. Broad scale genomic meta-analyses indicated that within a single organism, multiple iron transporters may contribute to iron acquisition. Here, we present a functional characterization of a cyanobacterial iron transport pathway that utilizes concerted transporter activities. Cyanobacteria are significant contributors to global primary productivity with high iron demands. Certain cyanobacterial species employ a siderophore-mediated uptake strategy; however, many strains possess neither siderophore biosynthesis nor siderophore transport genes. The unicellular, planktonic, freshwater cyanobacterium, Synechocystis sp. PCC 6803, employs an alternative to siderophore-based uptake-reduction of Fe(III) species before transport through the plasma membrane. In this study, we combine short-term radioactive iron uptake and reduction assays with a range of disruption mutants to generate a working model for iron reduction and uptake in Synechocystis sp. PCC 6803. We found that the Fe(II) transporter, FeoB, is the major iron transporter in this organism. In addition, we uncovered a link between a respiratory terminal oxidase (Alternate Respiratory Terminal Oxidase) and iron reduction - suggesting a coupling between these two electron transfer reactions. Furthermore, quantitative RNA transcript analysis identified a function for subunits of the Fe(III) transporter, FutABC, in modulating reductive iron uptake. Collectively, our results provide a molecular basis for a tightly coordinated, high-affinity iron transport system. PMID:24088625

  7. The liver: conductor of systemic iron balance

    PubMed Central

    Meynard, Delphine; Babitt, Jodie L.

    2014-01-01

    Iron is a micronutrient essential for almost all organisms: bacteria, plants, and animals. It is a metal that exists in multiple redox states, including the divalent ferrous (Fe2+) and the trivalent ferric (Fe3+) species. The multiple oxidation states of iron make it excellent for electron transfer, allowing iron to be selected during evolution as a cofactor for many proteins involved in central cellular processes including oxygen transport, mitochondrial respiration, and DNA synthesis. However, the redox cycling of ferrous and ferric iron in the presence of H2O2, which is physiologically present in the cells, also leads to the production of free radicals (Fenton reaction) that can attack and damage lipids, proteins, DNA, and other cellular components. To meet the physiological needs of the body, but to prevent cellular damage by iron, the amount of iron in the body must be tightly regulated. Here we review how the liver is the central conductor of systemic iron balance and show that this central role is related to the secretion of a peptide hormone hepcidin by hepatocytes. We then review how the liver receives and integrates the many signals that report the body’s iron needs to orchestrate hepcidin production and maintain systemic iron homeostasis. PMID:24200681

  8. Genetics and molecular biology of siderophore-mediated iron transport in bacteria.

    PubMed Central

    Crosa, J H

    1989-01-01

    The possession of specialized iron transport systems may be crucial for bacteria to override the iron limitation imposed by the host or the environment. One of the most commonly found strategies evolved by microorganisms is the production of siderophores, low-molecular-weight iron chelators that have very high constants of association for their complexes with iron. Thus, siderophores act as extracellular solubilizing agents for iron from minerals or organic compounds, such as transferrin and lactoferrin in the host vertebrate, under conditions of iron limitation. Transport of iron into the cell cytosol is mediated by specific membrane receptor and transport systems which recognize the iron-siderophore complexes. In this review I have analyzed in detail three siderophore-mediated iron uptake systems: the plasmid-encoded anguibactin system of Vibrio anguillarum, the aerobactin-mediated iron assimilation system present in the pColV-K30 plasmid and in the chromosomes of many enteric bacteria, and the chromosomally encoded enterobactin iron uptake system, found in Escherichia coli, Shigella spp., Salmonella spp., and other members of the family Enterobacteriaceae. The siderophore systems encoded by Pseudomonas aeruginosa, namely, pyochelin and pyoverdin, as well as the siderophore amonabactin, specified by Aeromonas hydrophila, are also discussed. The potential role of siderophore-mediated systems as virulence determinants in the specific host-bacteria interaction leading to disease is also analyzed with respect to the influence of these systems in the expression of other factors, such as toxins, in the bacterial virulence repertoire. PMID:2531838

  9. mRNA regulation of cardiac iron transporters and ferritin subunits in a mouse model of iron overload.

    PubMed

    Brewer, Casey J; Wood, Ruth I; Wood, John C

    2014-12-01

    Iron cardiomyopathy is the leading cause of death in iron overload. Men have twice the mortality rate of women, though the cause is unknown. In hemojuvelin-knockout mice, a model of the disease, males load more cardiac iron than females. We postulated that sex differences in cardiac iron import cause differences in cardiac iron concentration. Reverse transcription polymerase chain reaction was used to measure mRNA of cardiac iron transporters in hemojuvelin-knockout mice. No sex differences were discovered among putative importers of nontransferrin-bound iron (L-type and T-type calcium channels, ZRT/IRT-like protein 14 zinc channels). Transferrin-bound iron transporters were also analyzed; these are controlled by the iron regulatory element/iron regulatory protein (IRE/IRP) system. There was a positive relationship between cardiac iron and ferroportin mRNA in both sexes, but it was significantly steeper in females (p < 0.05). Transferrin receptor 1 and divalent metal transporter 1 were more highly expressed in females than males (p < 0.01 and p < 0.0001, respectively), consistent with their lower cardiac iron levels, as predicted by IRE/IRP regulatory pathways. Light-chain ferritin showed a positive correlation with cardiac iron that was nearly identical in males and females (R(2) = 0.41, p < 0.01; R(2) = 0.56, p < 0.05, respectively), whereas heavy-chain ferritin was constitutively expressed in both sexes. This represents the first report of IRE/IRP regulatory pathways in the heart. Transcriptional regulation of ferroportin was suggested in both sexes, creating a potential mechanism for differential set points for iron export. Constitutive heavy-chain-ferritin expression suggests a logical limit to cardiac iron buffering capacity at levels known to produce heart failure in humans. PMID:25220979

  10. Ascorbate Efflux as a New Strategy for Iron Reduction and Transport in Plants*

    PubMed Central

    Grillet, Louis; Ouerdane, Laurent; Flis, Paulina; Hoang, Minh Thi Thanh; Isaure, Marie-Pierre; Lobinski, Ryszard; Curie, Catherine; Mari, Stéphane

    2014-01-01

    Iron (Fe) is essential for virtually all living organisms. The identification of the chemical forms of iron (the speciation) circulating in and between cells is crucial to further understand the mechanisms of iron delivery to its final targets. Here we analyzed how iron is transported to the seeds by the chemical identification of iron complexes that are delivered to embryos, followed by the biochemical characterization of the transport of these complexes by the embryo, using the pea (Pisum sativum) as a model species. We have found that iron circulates as ferric complexes with citrate and malate (Fe(III)3Cit2Mal2, Fe(III)3Cit3Mal1, Fe(III)Cit2). Because dicotyledonous plants only transport ferrous iron, we checked whether embryos were capable of reducing iron of these complexes. Indeed, embryos did express a constitutively high ferric reduction activity. Surprisingly, iron(III) reduction is not catalyzed by the expected membrane-bound ferric reductase. Instead, embryos efflux high amounts of ascorbate that chemically reduce iron(III) from citrate-malate complexes. In vitro transport experiments on isolated embryos using radiolabeled 55Fe demonstrated that this ascorbate-mediated reduction is an obligatory step for the uptake of iron(II). Moreover, the ascorbate efflux activity was also measured in Arabidopsis embryos, suggesting that this new iron transport system may be generic to dicotyledonous plants. Finally, in embryos of the ascorbate-deficient mutants vtc2-4, vtc5-1, and vtc5-2, the reducing activity and the iron concentration were reduced significantly. Taken together, our results identified a new iron transport mechanism in plants that could play a major role to control iron loading in seeds. PMID:24347170

  11. Iron acquisition and regulation systems in Streptococcus species.

    PubMed

    Ge, Ruiguang; Sun, Xuesong

    2014-05-01

    Gram-positive Streptococcus species are responsible for millions of cases of meningitis, bacterial pneumonia, endocarditis, erysipelas and necrotizing fasciitis. Iron is essential for the growth and survival of Streptococcus in the host environment. Streptococcus species have developed various mechanisms to uptake iron from an environment with limited available iron. Streptococcus can directly extract iron from host iron-containing proteins such as ferritin, transferrin, lactoferrin and hemoproteins, or indirectly by relying on the employment of specialized secreted hemophores (heme chelators) and small siderophore molecules (high affinity ferric chelators). This review presents the most recent discoveries in the iron acquisition system of Streptococcus species - the transporters as well as the regulators.

  12. Iron, copper, zinc, and manganese transport and regulation in pathogenic Enterobacteria: correlations between strains, site of infection and the relative importance of the different metal transport systems for virulence

    PubMed Central

    Porcheron, Gaëlle; Garénaux, Amélie; Proulx, Julie; Sabri, Mourad; Dozois, Charles M.

    2013-01-01

    For all microorganisms, acquisition of metal ions is essential for survival in the environment or in their infected host. Metal ions are required in many biological processes as components of metalloproteins and serve as cofactors or structural elements for enzymes. However, it is critical for bacteria to ensure that metal uptake and availability is in accordance with physiological needs, as an imbalance in bacterial metal homeostasis is deleterious. Indeed, host defense strategies against infection either consist of metal starvation by sequestration or toxicity by the highly concentrated release of metals. To overcome these host strategies, bacteria employ a variety of metal uptake and export systems and finely regulate metal homeostasis by numerous transcriptional regulators, allowing them to adapt to changing environmental conditions. As a consequence, iron, zinc, manganese, and copper uptake systems significantly contribute to the virulence of many pathogenic bacteria. However, during the course of our experiments on the role of iron and manganese transporters in extraintestinal Escherichia coli (ExPEC) virulence, we observed that depending on the strain tested, the importance of tested systems in virulence may be different. This could be due to the different set of systems present in these strains, but literature also suggests that as each pathogen must adapt to the particular microenvironment of its site of infection, the role of each acquisition system in virulence can differ from a particular strain to another. In this review, we present the systems involved in metal transport by Enterobacteria and the main regulators responsible for their controlled expression. We also discuss the relative role of these systems depending on the pathogen and the tissues they infect. PMID:24367764

  13. Effects of developmental iron deficiency and post-weaning iron repletion on the levels of iron transporter proteins in rats

    PubMed Central

    Oh, Sugyoung; Shin, Pill-kyung

    2015-01-01

    BACKGROUND/OBJECTIVES Iron deficiency in early life is associated with developmental problems, which may persist until later in life. The question of whether iron repletion after developmental iron deficiency could restore iron homeostasis is not well characterized. In the present study, we investigated the changes of iron transporters after iron depletion during the gestational-neonatal period and iron repletion during the post-weaning period. MATERIALS/METHODS Pregnant rats were provided iron-deficient (< 6 ppm Fe) or control (36 ppm Fe) diets from gestational day 2. At weaning, pups from iron-deficient dams were fed either iron-deficient (ID group) or control (IDR group) diets for 4 week. Pups from control dams were continued to be fed with the control diet throughout the study period (CON). RESULTS Compared to the CON, ID rats had significantly lower hemoglobin and hematocrits in the blood and significantly lower tissue iron in the liver and spleen. Hepatic hepcidin and BMP6 mRNA levels were also strongly down-regulated in the ID group. Developmental iron deficiency significantly increased iron transporters divalent metal transporter 1 (DMT1) and ferroportin (FPN) in the duodenum, but decreased DMT1 in the liver. Dietary iron repletion restored the levels of hemoglobin and hematocrit to a normal range, but the tissue iron levels and hepatic hepcidin mRNA levels were significantly lower than those in the CON group. Both FPN and DMT1 protein levels in the liver and in the duodenum were not different between the IDR and the CON. By contrast, DMT1 in the spleen was significantly lower in the IDR, compared to the CON. The splenic FPN was also decreased in the IDR more than in the CON, although the difference did not reach statistical significance. CONCLUSIONS Our findings demonstrate that iron transporter proteins in the duodenum, liver and spleen are differentially regulated during developmental iron deficiency. Also, post-weaning iron repletion efficiently

  14. Chloroplast Iron Transport Proteins - Function and Impact on Plant Physiology.

    PubMed

    López-Millán, Ana F; Duy, Daniela; Philippar, Katrin

    2016-01-01

    Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field. PMID:27014281

  15. Atypical iron storage in marine brown algae: a multidisciplinary study of iron transport and storage in Ectocarpus siliculosus

    PubMed Central

    Matzanke, Berthold F.; Küpper, Frithjof C.; Carrano, Carl J.

    2012-01-01

    Iron is an essential element for all living organisms due to its ubiquitous role in redox and other enzymes, especially in the context of respiration and photosynthesis. The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood, with two basic strategies for iron uptake being distinguished: strategy I plants use a mechanism involving induction of Fe(III)-chelate reductase (ferrireductase) and Fe(II) transporter proteins, while strategy II plants utilize high-affinity, iron-specific, binding compounds called phytosiderophores. In contrast, little is known about the corresponding systems in marine, plant-like lineages, particularly those of multicellular algae (seaweeds). Herein the first study of the iron uptake and storage mechanisms in the brown alga Ectocarpus siliculosus is reported. Genomic data suggest that Ectocarpus may use a strategy I approach. Short-term radio-iron uptake studies verified that iron is taken up by Ectocarpus in a time- and concentration-dependent manner consistent with an active transport process. Upon long-term exposure to 57Fe, two metabolites have been identified using a combination of Mössbauer and X-ray absorption spectroscopies. These include an iron–sulphur cluster accounting for ~26% of the total intracellular iron pool and a second component with spectra typical of a polymeric (Fe3+O6) system with parameters similar to the amorphous phosphorus-rich mineral core of bacterial and plant ferritins. This iron metabolite accounts for ~74% of the cellular iron pool and suggests that Ectocarpus contains a non-ferritin but mineral-based iron storage pool. PMID:22945940

  16. Quercetin inhibits intestinal iron absorption and ferroportin transporter expression in vivo and in vitro.

    PubMed

    Lesjak, Marija; Hoque, Rukshana; Balesaria, Sara; Skinner, Vernon; Debnam, Edward S; Srai, Surjit K S; Sharp, Paul A

    2014-01-01

    Balancing systemic iron levels within narrow limits is critical for maintaining human health. There are no known pathways to eliminate excess iron from the body and therefore iron homeostasis is maintained by modifying dietary absorption so that it matches daily obligatory losses. Several dietary factors can modify iron absorption. Polyphenols are plentiful in human diet and many compounds, including quercetin--the most abundant dietary polyphenol--are potent iron chelators. The aim of this study was to investigate the acute and longer-term effects of quercetin on intestinal iron metabolism. Acute exposure of rat duodenal mucosa to quercetin increased apical iron uptake but decreased subsequent basolateral iron efflux into the circulation. Quercetin binds iron between its 3-hydroxyl and 4-carbonyl groups and methylation of the 3-hydroxyl group negated both the increase in apical uptake and the inhibition of basolateral iron release, suggesting that the acute effects of quercetin on iron transport were due to iron chelation. In longer-term studies, rats were administered quercetin by a single gavage and iron transporter expression measured 18 h later. Duodenal FPN expression was decreased in quercetin-treated rats. This effect was recapitulated in Caco-2 cells exposed to quercetin for 18 h. Reporter assays in Caco-2 cells indicated that repression of FPN by quercetin was not a transcriptional event but might be mediated by miRNA interaction with the FPN 3'UTR. Our study highlights a novel mechanism for the regulation of iron bioavailability by dietary polyphenols. Potentially, diets rich in polyphenols might be beneficial for patients groups at risk of iron loading by limiting the rate of intestinal iron absorption. PMID:25058155

  17. Quercetin Inhibits Intestinal Iron Absorption and Ferroportin Transporter Expression In Vivo and In Vitro

    PubMed Central

    Balesaria, Sara; Skinner, Vernon; Debnam, Edward S.; Srai, Surjit K. S.; Sharp, Paul A.

    2014-01-01

    Balancing systemic iron levels within narrow limits is critical for maintaining human health. There are no known pathways to eliminate excess iron from the body and therefore iron homeostasis is maintained by modifying dietary absorption so that it matches daily obligatory losses. Several dietary factors can modify iron absorption. Polyphenols are plentiful in human diet and many compounds, including quercetin – the most abundant dietary polyphenol – are potent iron chelators. The aim of this study was to investigate the acute and longer-term effects of quercetin on intestinal iron metabolism. Acute exposure of rat duodenal mucosa to quercetin increased apical iron uptake but decreased subsequent basolateral iron efflux into the circulation. Quercetin binds iron between its 3-hydroxyl and 4-carbonyl groups and methylation of the 3-hydroxyl group negated both the increase in apical uptake and the inhibition of basolateral iron release, suggesting that the acute effects of quercetin on iron transport were due to iron chelation. In longer-term studies, rats were administered quercetin by a single gavage and iron transporter expression measured 18 h later. Duodenal FPN expression was decreased in quercetin-treated rats. This effect was recapitulated in Caco-2 cells exposed to quercetin for 18 h. Reporter assays in Caco-2 cells indicated that repression of FPN by quercetin was not a transcriptional event but might be mediated by miRNA interaction with the FPN 3′UTR. Our study highlights a novel mechanism for the regulation of iron bioavailability by dietary polyphenols. Potentially, diets rich in polyphenols might be beneficial for patients groups at risk of iron loading by limiting the rate of intestinal iron absorption. PMID:25058155

  18. Nonredundant Roles of Iron Acquisition Systems in Vibrio cholerae.

    PubMed

    Peng, Eric D; Wyckoff, Elizabeth E; Mey, Alexandra R; Fisher, Carolyn R; Payne, Shelley M

    2015-12-07

    Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, thrives in both marine environments and the human host. To do so, it must encode the tools necessary to acquire essential nutrients, including iron, under these vastly different conditions. A number of V. cholerae iron acquisition systems have been identified; however, the precise role of each system is not fully understood. To test the roles of individual systems, we generated a series of mutants in which only one of the four systems that support iron acquisition on unsupplemented LB agar, Feo, Fbp, Vct, and Vib, remains functional. Analysis of these mutants under different growth conditions showed that these systems are not redundant. The strain carrying only the ferrous iron transporter Feo grew well at acidic, but not alkaline, pH, whereas the ferric iron transporter Fbp promoted better growth at alkaline than at acidic pH. A strain defective in all four systems (null mutant) had a severe growth defect under aerobic conditions but accumulated iron and grew as well as the wild type in the absence of oxygen, suggesting the presence of an additional, unidentified iron transporter in V. cholerae. In support of this, the null mutant was only moderately attenuated in an infant mouse model of infection. While the null mutant used heme as an iron source in vitro, we demonstrate that heme is not available to V. cholerae in the infant mouse intestine.

  19. Nonredundant Roles of Iron Acquisition Systems in Vibrio cholerae

    PubMed Central

    Peng, Eric D.; Wyckoff, Elizabeth E.; Mey, Alexandra R.; Fisher, Carolyn R.

    2015-01-01

    Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, thrives in both marine environments and the human host. To do so, it must encode the tools necessary to acquire essential nutrients, including iron, under these vastly different conditions. A number of V. cholerae iron acquisition systems have been identified; however, the precise role of each system is not fully understood. To test the roles of individual systems, we generated a series of mutants in which only one of the four systems that support iron acquisition on unsupplemented LB agar, Feo, Fbp, Vct, and Vib, remains functional. Analysis of these mutants under different growth conditions showed that these systems are not redundant. The strain carrying only the ferrous iron transporter Feo grew well at acidic, but not alkaline, pH, whereas the ferric iron transporter Fbp promoted better growth at alkaline than at acidic pH. A strain defective in all four systems (null mutant) had a severe growth defect under aerobic conditions but accumulated iron and grew as well as the wild type in the absence of oxygen, suggesting the presence of an additional, unidentified iron transporter in V. cholerae. In support of this, the null mutant was only moderately attenuated in an infant mouse model of infection. While the null mutant used heme as an iron source in vitro, we demonstrate that heme is not available to V. cholerae in the infant mouse intestine. PMID:26644383

  20. Iron transport in plants: better be safe than sorry.

    PubMed

    Thomine, Sébastien; Vert, Grégory

    2013-06-01

    Iron is essential for plant cell function and more specifically for photosynthesis. Plants have evolved highly efficient systems to take up iron from the soil. However, activating iron uptake is a double jeopardy: not only iron itself is toxic but iron uptake systems are poorly selective and allow the entry of other potentially toxic metals. Plants therefore tightly control iron uptake at the transcriptional and post-translational level and have evolved mechanisms to cope with the concomitant entry of toxic metals. In plant cells, iron has to be distributed to chloroplasts and mitochondria or may be stored safely in vacuole. Distinct transcriptional networks regulating uptake and intracellular distribution are being uncovered, while iron sensing mechanisms remain elusive.

  1. Ferric hydroxamate transport without subsequent iron utilization in Bacillus megaterium.

    PubMed Central

    Arceneaux, J E; Byers, B R

    1976-01-01

    Iron transport and utilization were examined in Bacillus megaterium Ard1, a mutant that is resistant to the hydroxymate antibiotic A22765 and whose growth is inhibited by the structurally similar hydroxamate Desferal. Rapid, low-level uptake of Desferal-50Fe was observed; such uptake was temperature and energy independent. Gel filtration chromatography of the cytoplasmic fraction of protoplasts labeled with Desferal-55Fe for 30 to 120 s demonstrated only unchanged esferal-55Fe in the cytoplasm. Although B. megaterium Ard1 showed transport of Desferal-59Fe by a process that resembles facilitated diffusion, this organism was unable to transfer iron from this chelate to cellular macromolecules for metabolic use. High-level transport of the ferric hydroxamate schizokinen-59Fe by B. megaterium Ard1 was both temperature and energy dependent. Within 30 s, protoplasts labeled with schizokinen-55Fe contained iron associated with certain macromolecules and in an apparent "pool" of schizokinen-55Fe in the cytoplasmic fraction. Prior transport of Dseferal-55Fe by protoplasts of strain Ard1 did not interfere with subsequent transport and utilization of schizokinen-59Fe. These studies suggest that transport of ferric hydroxamates may occur by a facilitated diffusion-type process; transfer of iron to cellular macromolecules may drive high-level transport of the chelate and may be the step at which energy is required in the iron transport-assimilation process. PMID:821926

  2. Thermal transport properties of grey cast irons

    SciTech Connect

    Hecht, R.L.; Dinwiddie, R.B.; Porter, W.D.; Wang, Hsin

    1996-10-01

    Thermal diffusivity and thermal conductivity of grey cast iron have been measured as a function of graphite flake morphology, chemical composition, and position in a finished brake rotor. Cast iron samples used for this investigation were cut from ``step block`` castings designed to produce iron with different graphite flake morphologies resulting from different cooling rates. Samples were also machined from prototype alloys and from production brake rotors representing a variation in foundry practice. Thermal diffusivity was measured at room and elevated temperatures via the flash technique. Heat capacity of selected samples was measured with differential scanning calorimetry, and these results were used to calculate the thermal conductivity. Microstructure of the various cast iron samples was quantified by standard metallography and image analysis, and the chemical compositions were determined by optical emission spectroscopy.

  3. A Systems Biology Approach to Iron Metabolism

    PubMed Central

    Chifman, J.; Laubenbacher, R.; Torti, S.V.

    2015-01-01

    Iron is critical to the survival of almost all living organisms. However, inappropriately low or high levels of iron are detrimental and contribute to a wide range of diseases. Recent advances in the study of iron metabolism have revealed multiple intricate pathways that are essential to the maintenance of iron homeostasis. Further, iron regulation involves processes at several scales, ranging from the subcellular to the organismal. This complexity makes a systems biology approach crucial, with its enabling technology of computational models based on a mathematical description of regulatory systems. Systems biology may represent a new strategy for understanding imbalances in iron metabolism and their underlying causes. PMID:25480643

  4. Shigella Iron Acquisition Systems and their Regulation

    PubMed Central

    Wei, Yahan; Murphy, Erin R.

    2016-01-01

    Survival of Shigella within the host is strictly dependent on the ability of the pathogen to acquire essential nutrients, such as iron. As an innate immune defense against invading pathogens, the level of bio-available iron within the human host is maintained at exceeding low levels, by sequestration of the element within heme and other host iron-binding compounds. In response to sequestration mediated iron limitation, Shigella produce multiple iron-uptake systems that each function to facilitate the utilization of a specific host-associated source of nutrient iron. As a mechanism to balance the essential need for iron and the toxicity of the element when in excess, the production of bacterial iron acquisition systems is tightly regulated by a variety of molecular mechanisms. This review summarizes the current state of knowledge on the iron-uptake systems produced by Shigella species, their distribution within the genus, and the molecular mechanisms that regulate their production. PMID:26904516

  5. Effect of water chemistry and aging on iron-mica interaction forces: implications for iron particle transport.

    PubMed

    Pensini, Erica; Yip, Christopher M; O'Carroll, Denis M; Sleep, Brent E

    2012-07-17

    The transport of particles through groundwater systems is governed by a complex interplay of mechanical and chemical forces that are ultimately responsible for binding to geological substrates. To understand these forces in the context of zero valent iron particles used in the remediation of groundwater, atomic force microscopy (AFM)-based force spectroscopy was employed to characterize the interactions between AFM tips modified with either carbonyl iron particles (CIP) or electrodeposited Fe as a function of counterion valency, temperature, particle morphology, and age. The measured interaction forces were always attractive for both fresh and aged CIP and electrodeposited iron, except in 100 mM NaCl, as a consequence of electrostatic attraction between the negatively charged mica and positively charged iron. In 100 mM NaCl, repulsive hydration forces appeared to dominate. Good agreement was found between the experimental data and predictions based on the extended DLVO (XDLVO) theory. The effect of aging on iron particle composition and morphology was assessed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) revealing that the aged particles comprising a zero valent iron core passivated by a mixture of iron oxides and hydroxides. Force spectroscopy showed that aging caused variations in the adhesive force due to the changes in particle morphology and contact area.

  6. Vacuolar Iron Transporter BnMEB2 Is Involved in Enhancing Iron Tolerance of Brassica napus.

    PubMed

    Zhu, Wei; Zuo, Rong; Zhou, Rongfang; Huang, Junyan; Tang, Minqiang; Cheng, Xiaohui; Liu, Yueying; Tong, Chaobo; Xiang, Yang; Dong, Caihua; Liu, Shengyi

    2016-01-01

    Iron toxicity is a nutrient disorder that severely affects crop development and yield in some soil conditions. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT) members are involved in this process and play essential roles in iron storage and transport. In this study, we identified a rapeseed VIT gene BnMEB2 (BnaC07g30170D) homologs to Arabidopsis MEB2 (At5g24290). Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old) leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other VIT genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops.

  7. Vacuolar Iron Transporter BnMEB2 Is Involved in Enhancing Iron Tolerance of Brassica napus

    PubMed Central

    Zhu, Wei; Zuo, Rong; Zhou, Rongfang; Huang, Junyan; Tang, Minqiang; Cheng, Xiaohui; Liu, Yueying; Tong, Chaobo; Xiang, Yang; Dong, Caihua; Liu, Shengyi

    2016-01-01

    Iron toxicity is a nutrient disorder that severely affects crop development and yield in some soil conditions. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT) members are involved in this process and play essential roles in iron storage and transport. In this study, we identified a rapeseed VIT gene BnMEB2 (BnaC07g30170D) homologs to Arabidopsis MEB2 (At5g24290). Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old) leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other VIT genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops. PMID:27679642

  8. Vacuolar Iron Transporter BnMEB2 Is Involved in Enhancing Iron Tolerance of Brassica napus

    PubMed Central

    Zhu, Wei; Zuo, Rong; Zhou, Rongfang; Huang, Junyan; Tang, Minqiang; Cheng, Xiaohui; Liu, Yueying; Tong, Chaobo; Xiang, Yang; Dong, Caihua; Liu, Shengyi

    2016-01-01

    Iron toxicity is a nutrient disorder that severely affects crop development and yield in some soil conditions. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT) members are involved in this process and play essential roles in iron storage and transport. In this study, we identified a rapeseed VIT gene BnMEB2 (BnaC07g30170D) homologs to Arabidopsis MEB2 (At5g24290). Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old) leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other VIT genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops.

  9. Vacuolar Iron Transporter BnMEB2 Is Involved in Enhancing Iron Tolerance of Brassica napus.

    PubMed

    Zhu, Wei; Zuo, Rong; Zhou, Rongfang; Huang, Junyan; Tang, Minqiang; Cheng, Xiaohui; Liu, Yueying; Tong, Chaobo; Xiang, Yang; Dong, Caihua; Liu, Shengyi

    2016-01-01

    Iron toxicity is a nutrient disorder that severely affects crop development and yield in some soil conditions. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT) members are involved in this process and play essential roles in iron storage and transport. In this study, we identified a rapeseed VIT gene BnMEB2 (BnaC07g30170D) homologs to Arabidopsis MEB2 (At5g24290). Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old) leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other VIT genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops. PMID:27679642

  10. Monoubiquitin-dependent endocytosis of the iron-regulated transporter 1 (IRT1) transporter controls iron uptake in plants.

    PubMed

    Barberon, Marie; Zelazny, Enric; Robert, Stéphanie; Conéjéro, Geneviève; Curie, Cathy; Friml, Jìrí; Vert, Grégory

    2011-08-01

    Plants take up iron from the soil using the iron-regulated transporter 1 (IRT1) high-affinity iron transporter at the root surface. Sophisticated regulatory mechanisms allow plants to tightly control the levels of IRT1, ensuring optimal absorption of essential but toxic iron. Here, we demonstrate that overexpression of Arabidopsis thaliana IRT1 leads to constitutive IRT1 protein accumulation, metal overload, and oxidative stress. IRT1 is unexpectedly found in trans-Golgi network/early endosomes of root hair cells, and its levels and localization are unaffected by iron nutrition. Using pharmacological approaches, we show that IRT1 cycles to the plasma membrane to perform iron and metal uptake at the cell surface and is sent to the vacuole for proper turnover. We also prove that IRT1 is monoubiquitinated on several cytosol-exposed residues in vivo and that mutation of two putative monoubiquitination target residues in IRT1 triggers stabilization at the plasma membrane and leads to extreme lethality. Together, these data suggest a model in which monoubiquitin-dependent internalization/sorting and turnover keep the plasma membrane pool of IRT1 low to ensure proper iron uptake and to prevent metal toxicity. More generally, our work demonstrates the existence of monoubiquitin-dependent trafficking to lytic vacuoles in plants and points to proteasome-independent turnover of plasma membrane proteins.

  11. Controls on radium transport by adsorption to iron minerals

    NASA Astrophysics Data System (ADS)

    Chen, M.; Wang, T.; Kocar, B. D.

    2015-12-01

    Radium is a naturally occurring radioactive metal found in many subsurface environments. Radium isotopes are generated by uranium and thorium decay, and are particularly abundant within groundwaters where minimal porewater flux leads to accumulation. These isotopes are used as natural tracers for estimating submarine groundwater discharge (SGD) [1], allowing for large scale estimation of GW fluxes into and out of the ocean [2]. They also represent a substantial hazard in wastewater produced after hydraulic fracturing for natural gas extraction [3], resulting in a significant risk of environmental release to surface and near-surface waters, and increased cost for water treatment or disposal. Adsorption to mineral surfaces represents a dominant pathway of radium retention in subsurface environments. For SGD studies, adsorption processes impact estimates of GW fluxes, while in hydraulic fracturing, radium adsorption to aquifer solids mediates wastewater radium activities. Analysis of past sorption studies revealed large variability in partition coefficients [4], while examination of radium adsorption kinetics and surface complexation have only recently started [5]. Accordingly, we present the results of sorption and column experiments of radium with a suite of iron minerals representative of those found within deep saline and near-surface (freshwater) aquifers, and evaluate impacts of varying salinity solutions through artificial waters. Further, we explore the impacts of pyrite oxidation and ferrihydrite transformation to other iron-bearing secondary minerals on the transport and retention of radium. These results will provide critical information on the mineralogical controls on radium retention in subsurface environments, and will therefore improve predictions of radium groundwater transport in natural and contaminated systems. [1] Charette, M.A., Buesseler, K.O. & Andrews, J.E., Limnol. Oceanogr. (2001). [2] Moore, W.S., Ann. Rev. Mar. Sci. (2010). [3] Vengosh, A

  12. Iron Homeostasis in Peripheral Nervous System, Still a Black Box?

    PubMed Central

    Taveggia, Carla

    2014-01-01

    Abstract Significance: Iron is the most abundant transition metal in biology and an essential cofactor for many cellular enzymes. Iron homeostasis impairment is also a component of peripheral neuropathies. Recent Advances: During the past years, much effort has been paid to understand the molecular mechanism involved in maintaining systemic iron homeostasis in mammals. This has been stimulated by the evidence that iron dyshomeostasis is an initial cause of several disorders, including genetic and sporadic neurodegenerative disorders. Critical Issues: However, very little has been done to investigate the physiological role of iron in peripheral nervous system (PNS), despite the development of suitable cellular and animal models. Future Directions: To stimulate research on iron metabolism and peripheral neuropathy, we provide a summary of the knowledge on iron homeostasis in the PNS, on its transport across the blood–nerve barrier, its involvement in myelination, and we identify unresolved questions. Furthermore, we comment on the role of iron in iron-related disorder with peripheral component, in demyelinating and metabolic peripheral neuropathies. Antioxid. Redox Signal. 21, 634–648. PMID:24409826

  13. Transportation System Requirements Document

    SciTech Connect

    Not Available

    1993-09-01

    This Transportation System Requirements Document (Trans-SRD) describes the functions to be performed by and the technical requirements for the Transportation System to transport spent nuclear fuel (SNF) and high-level radioactive waste (HLW) from Purchaser and Producer sites to a Civilian Radioactive Waste Management System (CRWMS) site, and between CRWMS sites. The purpose of this document is to define the system-level requirements for Transportation consistent with the CRWMS Requirement Document (CRD). These requirements include design and operations requirements to the extent they impact on the development of the physical segments of Transportation. The document also presents an overall description of Transportation, its functions, its segments, and the requirements allocated to the segments and the system-level interfaces with Transportation. The interface identification and description are published in the CRWMS Interface Specification.

  14. Transgenic petunia with the iron(III)-phytosiderophore transporter gene acquires tolerance to iron deficiency in alkaline environments.

    PubMed

    Murata, Yoshiko; Itoh, Yoshiyuki; Iwashita, Takashi; Namba, Kosuke

    2015-01-01

    Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of iron(III) to iron(II) and the uptake of iron(II) by the iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble iron(III). Strategy II comprises the synthesis and secretion of iron-chelating phytosiderophores, such as mugineic acids and the Yellow Stripe 1 transporter proteins of the iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to iron deficiency in alkaline soil among graminaceous plants, utilizes mugineic acids and the specific iron(III)-mugineic acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2'-deoxymugineic acid complex, free 2'-deoxymugineic acid and its iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2'-deoxymugineic acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide iron uptake problems to diverse

  15. A vacuolar iron-transporter homologue acts as a detoxifier in Plasmodium

    PubMed Central

    Slavic, Ksenija; Krishna, Sanjeev; Lahree, Aparajita; Bouyer, Guillaume; Hanson, Kirsten K.; Vera, Iset; Pittman, Jon K.; Staines, Henry M.; Mota, Maria M.

    2016-01-01

    Iron is an essential micronutrient but is also highly toxic. In yeast and plant cells, a key detoxifying mechanism involves iron sequestration into intracellular storage compartments, mediated by members of the vacuolar iron-transporter (VIT) family of proteins. Here we study the VIT homologue from the malaria parasites Plasmodium falciparum (PfVIT) and Plasmodium berghei (PbVIT). PfVIT-mediated iron transport in a yeast heterologous expression system is saturable (Km∼14.7 μM), and selective for Fe2+ over other divalent cations. PbVIT-deficient P. berghei lines (Pbvit−) show a reduction in parasite load in both liver and blood stages of infection in mice. Moreover, Pbvit− parasites have higher levels of labile iron in blood stages and are more sensitive to increased iron levels in liver stages, when compared with wild-type parasites. Our data are consistent with Plasmodium VITs playing a major role in iron detoxification and, thus, normal development of malaria parasites in their mammalian host. PMID:26786069

  16. Experimental data to demonstrate the density influenced transport characteristics of stabilized iron nanoparticles

    NASA Astrophysics Data System (ADS)

    Clement, T. P.; Kanel, S. R.; Goswami, R. R.; Barnett, M. O.

    2008-12-01

    Zero valent iron nanoparticles (INP) are often used to treat various types of environmental contaminants. In this study, we synthesized a new class of iron nanoparticles and stabilized it using poly-acrylic acid (PAA). A two dimensional groundwater aquifer model was used to study the fate and transport of pristine INP and SINP (stabilized iron nano particles) under steady-state flow conditions. Transport data for a non-reactive tracer, INP, and SINP were collected under similar experimental conditions. The results clearly demonstrate the ability of PAA to stabilize INP. Furthermore, the transport data indicated that the S-INP plume will sink in a groundwater aquifer, indicating that small density gradients have significant influence on two-dimensional transport. This observation has enormous implication for designing field scale remediation systems that use iron nano particles. We used the variable-density groundwater model SEAWAT to model INP as a density driven tracer. The model results along with the experimental data show that the density influence transport controlled the migration patterns of SINP. Since the influence of density effects cannot be fully discerned using column experiments, two dimensional experiments are essential for fully understanding the transport characteristics of INP.

  17. Subseabed disposal transportation system

    SciTech Connect

    Allen, Jr., G. C.; Vernon, M. E.; Anderson, D. R.

    1980-01-01

    Transportation requirements and interfaces are being considered in the evaluation of the seabed disposal option. Technical direction and planning are on-going to ensure the development of major transportation systems in support of the seabed disposal option. Factors which affect the risk and effectiveness of transportation are being included in site selection criteria. However, detailed development of port facilities and transport/emplacement equipment is still several years into the future. (DMC)

  18. Modeling the processing of mineral iron during dust transport

    NASA Astrophysics Data System (ADS)

    Vogelsberg, Ulrike; Wolke, Ralf; Tilgner, Andreas; Tegen, Ina; Herrmann, Hartmut

    2014-05-01

    The Saharan desert and the Gobi desert are the main contributors to Aeolian desert dust, which is a major source of micronutrients to the remote ocean regions. Micronutrients, such as transition metals like iron or copper, are regarded essential for biological processes of different marine species. In this context recent studies have shown that soluble iron, since it is generally the most abundant transition metal in dust particles, has the ability to control marine productivity and thereby likely influence the CO2- budget. Nevertheless, the processing of desert dust leading to the release of soluble iron still lacks sufficient understanding since several factors control the solubilization process. Especially anthropogenic emissions are regarded to significantly add to the amount of soluble iron by acidification of dust particles or by the direct emission of soluble iron comprised, e.g. in coal fly ash. For the investigation of the dissolution process of iron that takes place during dust transportation the spectral air parcel model SPACCIM is used. A mechanism describing the precipitation and dissolution of mineral particles by heterogeneous surface reactions has been implemented. Trajectory properties were derived from COSMO-MUSCAT simulations or from re-analysis data by HYSPLIT. Differences in the chemical composition and the amount of anthropogenic and naturally emitted species on the North African continent and the highly industrialized region of South-East Asia have considerable impact on the acidification of the desert dust. Under this aspect, special cases of dust outbreaks of the Saharan desert and the Gobi desert are investigated and compared with focus on soluble iron produced.

  19. Payload transportation system study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A standard size set of shuttle payload transportation equipment was defined that will substantially reduce the cost of payload transportation and accommodate a wide range of payloads with minimum impact on payload design. The system was designed to accommodate payload shipments between the level 4 payload integration sites and the launch site during the calendar years 1979-1982. In addition to defining transportation multi-use mission support equipment (T-MMSE) the mode of travel, prime movers, and ancillary equipment required in the transportation process were also considered. Consistent with the STS goals of low cost and the use of standardized interfaces, the transportation system was designed to commercial grade standards and uses the payload flight mounting interfaces for transportation. The technical, cost, and programmatic data required to permit selection of a baseline system of MMSE for intersite movement of shuttle payloads were developed.

  20. Space Transportation Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Stewart, Mark E.; Suresh, Ambady; Owen, A. Karl

    2001-01-01

    This report outlines the Space Transportation Propulsion Systems for the NPSS (Numerical Propulsion System Simulation) program. Topics include: 1) a review of Engine/Inlet Coupling Work; 2) Background/Organization of Space Transportation Initiative; 3) Synergy between High Performance Computing and Communications Program (HPCCP) and Advanced Space Transportation Program (ASTP); 4) Status of Space Transportation Effort, including planned deliverables for FY01-FY06, FY00 accomplishments (HPCCP Funded) and FY01 Major Milestones (HPCCP and ASTP); and 5) a review current technical efforts, including a review of the Rocket-Based Combined-Cycle (RBCC), Scope of Work, RBCC Concept Aerodynamic Analysis and RBCC Concept Multidisciplinary Analysis.

  1. A multidisciplinary study of iron transport and storage in the marine green alga Tetraselmis suecica.

    PubMed

    Hartnett, Andrej; Böttger, Lars H; Matzanke, Berthold F; Carrano, Carl J

    2012-11-01

    The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood with two basic strategies being distinguished: strategy I involves the induction of a Fe(III)-chelate reductase (ferrireductase) along with Fe(II) or Fe(III) transporter proteins while strategy II plants have evolved sophisticated systems based on high-affinity, iron specific, binding compounds called phytosiderophores. In contrast, there is little knowledge about the corresponding systems in marine, plant-like lineages. Herein we report a study of the iron uptake and storage mechanisms in the green alga Tetraselmis suecica. Short term radio-iron uptake studies indicate that iron is taken up by Tetraselmis in a time and concentration dependent manner consistent with an active transport process. Based on inhibitor and other studies it appears that a reductive-oxidative pathway such as that found in yeast and the green alga Chlamydomonas reinhardtii is likely. Upon long term exposure to (57)Fe we have been able, using a combination of Mössbauer and X-ray absorption spectroscopies, to identify three metabolites. The first exhibits Mössbauer parameters typical of a [Fe(4)S(4)](2+) cluster and which accounts for approximately 10% of the total intracellular iron pool. The second displays a spectrum typical of a [Fe(II)O(6)] system accounting for approximately 2% of the total pool. The largest component (ca. 85+%) consists of polymeric iron-oxo mineral species with parameters between that of the crystalline ferrihydrite core of animal ferritins and the amorphous hydrated ferric phosphate of bacterial and plant ferritins.

  2. A solute-binding protein for iron transport in Streptococcus iniae

    PubMed Central

    2010-01-01

    Background Streptococcus iniae (S. iniae) is a major pathogen that causes considerable morbidity and mortality in cultured fish worldwide. The pathogen's ability to adapt to the host affects the extent of infection, hence understanding the mechanisms by which S. iniae overcomes physiological stresses during infection will help to identify potential virulence determinants of streptococcal infection. Grow S. iniae under iron-restricted conditions is one approach for identifying host-specific protein expression. Iron plays an important role in many biological processes but it has low solubility under physiological condition. Many microorganisms have been shown to be able to circumvent this nutritional limitation by forming direct contacts with iron-containing proteins through ATP-binding cassette (ABC) transporters. The ABC transporter superfamilies constitute many different systems that are widespread among living organisms with different functions, such as ligands translocation, mRNA translation, and DNA repair. Results An ABC transporter system, named as mtsABC (metal transport system) was cloned from S. iniae HD-1, and was found to be involved in heme utilization. mtsABC is cotranscribed by three downstream genes, i.e., mtsA, mtsB, and mtsC. In this study, we cloned the first gene of the mtsABC transporter system (mtsA), and purified the corresponding recombinant protein MtsA. The analysis indicated that MtsA is a putative lipoprotein which binds to heme that can serve as an iron source for the microorganism, and is expressed in vivo during Kunming mice infection by S. iniae HD-1. Conclusions This is believed to be the first report on the cloning the ABC transporter lipoprotein from S. iniae genomic DNA. Together, our data suggested that MtsA is associated with heme, and is expressed in vivo during Kunming mice infection by S. iniae HD-1 which indicated that it can be a potential candidate for S. iniae subunit vaccine. PMID:21122131

  3. Smart vehicular transportation systems

    SciTech Connect

    Little, C.Q.; Wilson, C.W.

    1997-05-01

    This work builds upon established Sandia intelligent systems technology to develop a unique approach for the integration of intelligent system control into the US Highway and urban transportation systems. The Sandia developed concept of the COPILOT controller integrates a human driver with computer control to increase human performance while reducing reliance on detailed driver attention. This research extends Sandia expertise in sensor based, real-time control of robotics systems to high speed transportation systems. Knowledge in the form of maps and performance characteristics of vehicles provides the automatic decision making intelligence needed to plan optimum routes, maintain safe driving speeds and distances, avoid collisions, and conserve fuel.

  4. The transferrin-iron import system from pathogenic Neisseria species.

    PubMed

    Noinaj, Nicholas; Buchanan, Susan K; Cornelissen, Cynthia Nau

    2012-10-01

    Two pathogenic species within the genus Neisseria cause the diseases gonorrhoea and meningitis. While vaccines are available to protect against four N. meningitidis serogroups, there is currently no commercial vaccine to protect against serogroup B or against N. gonorrhoeae. Moreover, the available vaccines have significant limitations and with antibiotic resistance becoming an alarming issue, the search for effective vaccine targets to elicit long-lasting protection against Neisseria species is becoming more urgent. One strategy for vaccine development has targeted the neisserial iron import systems. Without iron, the Neisseriae cannot survive and, therefore, these iron import systems tend to be relatively well conserved and are promising vaccine targets, having the potential to offer broad protection against both gonococcal and meningococcal infections. These efforts have been boosted by recent reports of the crystal structures of the neisserial receptor proteins TbpA and TbpB, each solved in complex with human transferrin, an iron binding protein normally responsible for delivering iron to human cells. Here, we review the recent structural reports and put them into perspective with available functional studies in order to derive the mechanism(s) for how the pathogenic Neisseriae are able to hijack human iron transport systems for their own survival and pathogenesis. PMID:22957710

  5. The transferrin-iron import system from pathogenic Neisseria species.

    PubMed

    Noinaj, Nicholas; Buchanan, Susan K; Cornelissen, Cynthia Nau

    2012-10-01

    Two pathogenic species within the genus Neisseria cause the diseases gonorrhoea and meningitis. While vaccines are available to protect against four N. meningitidis serogroups, there is currently no commercial vaccine to protect against serogroup B or against N. gonorrhoeae. Moreover, the available vaccines have significant limitations and with antibiotic resistance becoming an alarming issue, the search for effective vaccine targets to elicit long-lasting protection against Neisseria species is becoming more urgent. One strategy for vaccine development has targeted the neisserial iron import systems. Without iron, the Neisseriae cannot survive and, therefore, these iron import systems tend to be relatively well conserved and are promising vaccine targets, having the potential to offer broad protection against both gonococcal and meningococcal infections. These efforts have been boosted by recent reports of the crystal structures of the neisserial receptor proteins TbpA and TbpB, each solved in complex with human transferrin, an iron binding protein normally responsible for delivering iron to human cells. Here, we review the recent structural reports and put them into perspective with available functional studies in order to derive the mechanism(s) for how the pathogenic Neisseriae are able to hijack human iron transport systems for their own survival and pathogenesis.

  6. Reactive iron transport in an acidic mountain stream in Summit County, Colorado: A hydrologic perspective

    USGS Publications Warehouse

    McKnight, Diane M.; Bencala, K.E.

    1989-01-01

    A pH perturbation experiment was conducted in an acidic, metal-enriched, mountain stream to identify relative rates of chemical and hydrologic processes as they influence iron transport. During the experiment the pH was lowered from 4.2 to 3.2 for three hours by injection of sulfuric acid. Amorphous iron oxides are abundant on the streambed, and dissolution and photoreduction reactions resulted in a rapid increase in the dissolved iron concentration. The increase occurred simultaneously with the decrease in pH. Ferrous iron was the major aqueous iron species. The changes in the iron concentration during the experiment indicate that variation exists in the solubility properties of the hydrous iron oxides on the streambed with dissolution of at least two compartments of hydrous iron oxides contributing to the iron pulse. Spatial variations of the hydrologic properties along the stream were quantified by simulating the transport of a coinjected tracer, lithium. A simulation of iron transport, as a conservative solute, indicated that hydrologie transport had a significant role in determining downstream changes in the iron pulse. The rapidity of the changes in iron concentration indicates that a model based on dynamic equilibrium may be adequate for simulating iron transport in acid streams. A major challenge for predictive solute transport models of geochemical processes may be due to substantial spatial and seasonal variations in chemical properties of the reactive hydrous oxides in such streams, and in the physical and hydrologic properties of the stream. ?? 1989.

  7. Intracellular Iron Transport and Storage: From Molecular Mechanisms to Health Implications

    PubMed Central

    Mackenzie, Elizabeth L.; Iwasaki, Kenta

    2008-01-01

    Abstract Maintenance of proper “labile iron” levels is a critical component in preserving homeostasis. Iron is a vital element that is a constituent of a number of important macromolecules, including those involved in energy production, respiration, DNA synthesis, and metabolism; however, excess “labile iron” is potentially detrimental to the cell or organism or both because of its propensity to participate in oxidation–reduction reactions that generate harmful free radicals. Because of this dual nature, elaborate systems tightly control the concentration of available iron. Perturbation of normal physiologic iron concentrations may be both a cause and a consequence of cellular damage and disease states. This review highlights the molecular mechanisms responsible for regulation of iron absorption, transport, and storage through the roles of key regulatory proteins, including ferroportin, hepcidin, ferritin, and frataxin. In addition, we present an overview of the relation between iron regulation and oxidative stress and we discuss the role of functional iron overload in the pathogenesis of hemochromatosis, neurodegeneration, and inflammation. Antioxid. Redox Signal. 10, 997–1030. PMID:18327971

  8. A Streptococcus pneumoniae pathogenicity island encoding an ABC transporter involved in iron uptake and virulence.

    PubMed

    Brown, J S; Gilliland, S M; Holden, D W

    2001-05-01

    Restricted iron availability is a major obstacle to growth and survival of pathogenic bacteria during infection. In contrast to Gram-negative pathogens, little is known about how Gram-positive pathogens obtain this essential metal. We have identified two Streptococcus pneumoniae genetic loci, pit1 and pit2, encoding homologues of ABC iron transporters that are required for iron uptake by this organism. S. pneumoniae strains containing disrupted copies of either pit1 or pit2 had decreased sensitivity to the iron-dependent antibiotic streptonigrin, and a strain containing disrupted copies of both pit1 and pit2 was unable to use haemoglobin as an iron source and had a reduced rate of iron uptake. The pit2- strain was moderately and the pit1-/pit2- strain strongly attenuated in virulence in mouse models of pulmonary and systemic infection, showing that the pit loci play a critical role during in vivo growth of S. pneumoniae. The pit2 locus is contained within a 27 kb region of chromosomal DNA that has several features of Gram-negative bacterial pathogenicity islands. This probable pathogenicity island (PPI-1) is the first to be described for S. pneumoniae, and its acquisition is likely to have played a significant role in the evolution of this important human pathogen.

  9. Transgenic Petunia with the Iron(III)-Phytosiderophore Transporter Gene Acquires Tolerance to Iron Deficiency in Alkaline Environments

    PubMed Central

    Murata, Yoshiko; Itoh, Yoshiyuki; Iwashita, Takashi; Namba, Kosuke

    2015-01-01

    Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of iron(III) to iron(II) and the uptake of iron(II) by the iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble iron(III). Strategy II comprises the synthesis and secretion of iron-chelating phytosiderophores, such as mugineic acids and the Yellow Stripe 1 transporter proteins of the iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to iron deficiency in alkaline soil among graminaceous plants, utilizes mugineic acids and the specific iron(III)-mugineic acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2′-deoxymugineic acid complex, free 2′-deoxymugineic acid and its iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2′-deoxymugineic acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide iron uptake problems to

  10. Coupled transport protein systems.

    PubMed

    Thatcher, Jack D

    2013-04-16

    This set of animated lessons provides examples of how transport proteins interact in coupled systems to produce physiologic effects. The gastric pumps animation depicts the secretion of hydrochloric acid into the gastric lumen. The animation called glucose absorption depicts glucose absorption by intestinal epithelial cells. The CFTR animation explains how the cystic fibrosis conductance transmembrane regulator (CFTR) functions as a key component of a coupled system of transport proteins that clears the pulmonary system of mucus and inhaled particulates. These animations serve as valuable resources for any collegiate-level course that describes these processes. Courses that might use them include introductory biology, biochemistry, biophysics, cell biology, pharmacology, and physiology.

  11. Iron-induced reactive oxygen species mediate transporter DMT1 endocytosis and iron uptake in intestinal epithelial cells.

    PubMed

    Esparza, Andrés; Gerdtzen, Ziomara P; Olivera-Nappa, Alvaro; Salgado, J Cristian; Núñez, Marco T

    2015-10-15

    Recent evidence shows that iron induces the endocytosis of the iron transporter dimetal transporter 1 (DMT1) during intestinal absorption. We, and others, have proposed that iron-induced DMT1 internalization underlies the mucosal block phenomena, a regulatory response that downregulates intestinal iron uptake after a large oral dose of iron. In this work, we investigated the participation of reactive oxygen species (ROS) in the establishment of this response. By means of selective surface protein biotinylation of polarized Caco-2 cells, we determined the kinetics of DMT1 internalization from the apical membrane after an iron challenge. The initial decrease in DMT1 levels in the apical membrane induced by iron was followed at later times by increased levels of DMT1. Addition of Fe(2+), but not of Cd(2+), Zn(2+), Cu(2+), or Cu(1+), induced the production of intracellular ROS, as detected by 2',7'-dichlorofluorescein (DCF) fluorescence. Preincubation with the antioxidant N-acetyl-l-cysteine (NAC) resulted in increased DMT1 at the apical membrane before and after addition of iron. Similarly, preincubation with the hydroxyl radical scavenger dimethyl sulfoxide (DMSO) resulted in the enhanced presence of DMT1 at the apical membrane. The decrease of DMT1 levels at the apical membrane induced by iron was associated with decreased iron uptake rates. A kinetic mathematical model based on operational rate constants of DMT1 endocytosis and exocytosis is proposed. The model qualitatively captures the experimental observations and accurately describes the effect of iron, NAC, and DMSO on the apical distribution of DMT1. Taken together, our data suggest that iron uptake induces the production of ROS, which modify DMT1 endocytic cycling, thus changing the iron transport activity at the apical membrane.

  12. Local Pathways in Coherent Electron Transport through Iron Porphyrin Complexes: A Challenge for First-Principles Transport Calculations

    SciTech Connect

    Herrmann, C.; Solomon, G.C.; Ratner, Mark A.

    2010-12-09

    We investigate the coherent electron transport properties of a selection of iron porphyrin complexes in their low-spin and high-spin states, binding the system to metallic electrodes with three different substitution patterns. We use a study of the local transmission through the complexes and their molecular orbitals to show the role of the various components of the molecular structure in mediating electron transport. While there are energies where the metal center and the axial ligands participate in transport, in the off-resonant energy range, these components simply form a scaffold, and the transport is dominated by transmission through the porphyrin macrocyle alone. This is still true when going from the low-spin to the high-spin state, except that now, an additional iron-centered MO contributes to transport in the formerly off-resonant region. It is found that while the choice of the exchange-correlation functional can strongly influence the quantitative results, our qualitative conclusions hold irrespective of the functional employed.

  13. Calcium channel blockers ameliorate iron overload-associated hepatic fibrosis by altering iron transport and stellate cell apoptosis.

    PubMed

    Zhang, Ying; Zhao, Xin; Chang, Yanzhong; Zhang, Yuanyuan; Chu, Xi; Zhang, Xuan; Liu, Zhenyi; Guo, Hui; Wang, Na; Gao, Yonggang; Zhang, Jianping; Chu, Li

    2016-06-15

    Liver fibrosis is the principal cause of morbidity and mortality in patients with iron overload. Calcium channel blockers (CCBs) can antagonize divalent cation entry into renal and myocardial cells and inhibit fibrogenic gene expression. We investigated the potential of CCBs to resolve iron overload-associated hepatic fibrosis. Kunming mice were assigned to nine groups (n=8 per group): control, iron overload, deferoxamine, high and low dose verapamil, high and low dose nimodipine, and high and low dose diltiazem. Iron deposition and hepatic fibrosis were measured in mouse livers. Expression levels of molecules associated with transmembrane iron transport were determined by molecular biology approaches. In vitro HSC-T6 cells were randomized into nine groups (the same groups as the mice). Changes in proliferation, apoptosis, and metalloproteinase expression in cells were detected to assess the anti-fibrotic effects of CCBs during iron overload conditions. We found that CCBs reduced hepatic iron content, intracellular iron deposition, the number of hepatic fibrotic areas, collagen expression levels, and hydroxyproline content. CCBs rescued abnormal expression of α1C protein in L-type voltage-dependent calcium channel (LVDCC) and down-regulated divalent metal transporter-1 (DMT-1) expression in mouse livers. In iron-overloaded HSC-T6 cells, CCBs reduced iron deposition, inhibited proliferation, induced apoptosis, and elevated expression of matrix metalloproteinase-13 (MMP-13) and tissue inhibitor of metalloproteinase-1 (TIMP-1). CCBs are potential therapeutic agents that can be used to address hepatic fibrosis during iron overload. They resolve hepatic fibrosis probably correlated with regulating transmembrane iron transport and inhibiting HSC growth. PMID:27095094

  14. Regulation of ferric iron transport in Escherichia coli K12: isolation of a constitutive mutant.

    PubMed

    Hantke, K

    1981-01-01

    The lac genes were inserted with phage Mu(Ap, lac) into the fhuA, fepA, cir and tonB genes which specify components of iron uptake systems. The expression of lac in all these operon fusions was controlled by the availability of iron to the cells, thereby facilitating a quick and simple measurement of the expression of the genes listed above. In an iron rich medium under anaerobic conditions all systems were strongly repressed. fhuA was depressed at higher iron concentration than was fepA or cir, and tonB was repressed only under anaerobic conditions and could be induced by iron limitation. Mutants constitutive for the expression of beta-galactosidase were selected in a fhuA-lac fusion strain. The outer membrane proteins Cir, FhuA, FecA, 76K and 83K were made constitutively in such mutant strains. Therefore, they were termed fur mutants. In these fur mutant strains, the synthesis of a 19K protein was reduced. Furthermore, it was found that transport of ferric enterochelin and ferrichrome was also constitutive in the fur mutant cells, and that ferric citrate uptake could be induced by only 10 microM citrate in the growth medium in contrast to wild-type cells in which at least 100 microM citrate was necessary. The fepA gene was concluded to be under an additional control, because it was not fully derepressed by the fur mutation. PMID:7026976

  15. Transportation Systems Evaluation

    NASA Technical Reports Server (NTRS)

    Fanning, M. L.; Michelson, R. A.

    1972-01-01

    A methodology for the analysis of transportation systems consisting of five major interacting elements is reported. The analysis begins with the causes of travel demand: geographic, economic, and demographic characteristics as well as attitudes toward travel. Through the analysis, the interaction of these factors with the physical and economic characteristics of the transportation system is determined. The result is an evaluation of the system from the point of view of both passenger and operator. The methodology is applicable to the intraurban transit systems as well as major airlines. Applications of the technique to analysis of a PRT system and a study of intraurban air travel are given. In the discussion several unique models or techniques are mentioned: i.e., passenger preference modeling, an integrated intraurban transit model, and a series of models to perform airline analysis.

  16. Transport of carbon colloid supported nanoscale zero-valent iron in porous media

    NASA Astrophysics Data System (ADS)

    Busch, Jan; Oswald, Sascha

    2013-04-01

    The use of nano zero-valent iron (nZVI) for environmental remediation is an emerging technology for in situ remediation of contaminated groundwater. Due to its high surface area and high reactivity nZVI is able to dechlorinate organic contaminants and render them to less harmful substances. Carbo-Iron is a newly developed material consisting of activated carbon particles (d50 = 0.6 - 2.4 µm) that are doted with nZVI particles. These particles combine the sorption capacity of activated carbon and the reactivity of nZVI. Additionally the main limitation for nZVI delivery, a limited mobility due to fast aggregation and sedimentation of nZVI in dispersions and soils, might be solved. According to transport theory, particles with a diameter of approximately 1 µm are more mobile than unsupported nZVI particles in sandy aquifer systems. Results from column tests and a two dimensional laboratory aquifer test system are presented: Column tests using columns of 40 cm length were filled with sand. A particle suspension was pumped against gravity through the system. Results show, addition of a polyanionic stabilizer such as Carboxymethylcellulouse (CMC) is required to enhancing mobility. Ionic strength and pH concentrations in an environmental relevant range do not interfere significantly with transport, but particle size was found to be crucial. Another experiment was performed in a two dimensional aquifer test system. The test system contains a sand filled container with a inner size of 40 x 5 x 110 cm and seven ports on each side. A constant flow of water was applied from the left to the right side through all ports and the middle port was fed with a Carbo-Iron suspension. Results show a transport through the laboratory aquifer within few exchanged pore volumes, and breakthrough of Carbo-Iron at the outlet. Deposits of immobile Carbo-Iron were found to be decreasing with distance from the injection port. No gravity effects were observed. Results suggest high mobility of

  17. A novel MFS transporter encoding gene in Fusarium verticillioides probably involved in iron-siderophore transport.

    PubMed

    López-Errasquín, Elena; González-Jaén, M Teresa; Callejas, Carmen; Vázquez, Covadonga

    2006-09-01

    The major facilitator superfamily (MFS) is a ubiquitous group of proteins involved in the transport of a wide range of compounds, including toxins produced by fungal species. In this paper, a novel MFS encoding gene (Fusarium iron related gene or FIR1), which had shown an up-regulation in fumonisin-inducing conditions, has been identified and characterized. The deduced protein sequence, which predicted 14 transmembrane domains typical of MFS transporters and its phylogenetic relationships with representative members of MFS transporters suggested a possible function of FIR1 as a siderophore transporter. A real-time RT-PCR protocol has been developed to analyse the expression pattern of the FIR1 gene in relation to siderophore production. The results indicated that the synthesis of extracellular siderophores by F. verticillioides observed in absence of extracellular iron was repressed in iron-supplemented cultures and showed a good correspondence with FIR1 gene expression. However, the pattern of FIR1 gene expression observed suggested that this gene did not seem to be functionally related to fumonisin production.

  18. Transportation Anslysis Simulation System

    SciTech Connect

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at the level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not account

  19. Transportation Anslysis Simulation System

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at themore » level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not

  20. A lunar transportation system

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Due to large amounts of oxygen required for space travel, a method of mining, transporting, and storing this oxygen in space would facilitate further space exploration. The following project deals specifically with the methods for transporting liquid oxygen from the lunar surface to the Lunar Orbit (LO) space station, and then to the Lower Earth Orbit (LEO) space station. Two vehicles were designed for operation between the LEO and LO space stations. The first of these vehicles is an aerobraked design vehicle. The Aerobrake Orbital Transfer Vehicle (OTV) is capable of transporting 5000 lbm of payload to LO while returning to LEO with 60,000 lbm of liquid oxygen, and thus meet mission requirements. The second vehicle can deliver 18,000 lbm of payload to LO and is capable of bringing 60,000 lbm of liquid oxygen back to LEO. A lunar landing vehicle was also designed for operation between LO and the established moon base. The use of an electromagnetic railgun as a method for launching the lunar lander was also investigated. The feasibility of the railgun is doubtful at this time. A system of spheres was also designed for proper storing and transporting of the liquid oxygen. The system assumes a safe means for transferring the liquid oxygen from tank to tank is operational. A sophisticated life support system was developed for both the OTV and the lunar lander. This system focuses on such factors as the vehicle environment, waste management, water requirements, food requirements, and oxygen requirements.

  1. Lunar transportation system

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The University Space Research Association (USRA) requested the University of Minnesota Spacecraft Design Team to design a lunar transportation infrastructure. This task was a year long design effort culminating in a complete conceptual design and presentation at Johnson Space Center. The mission objective of the design group was to design a system of vehicles to bring a habitation module, cargo, and crew to the lunar surface from LEO and return either or both crew and cargo safely to LEO while emphasizing component commonality, reusability, and cost effectiveness. During the course of the design, the lunar transportation system (LTS) has taken on many forms. The final design of the system is composed of two vehicles, a lunar transfer vehicle (LTV) and a lunar excursion vehicle (LEV). The LTV serves as an efficient orbital transfer vehicle between the earth and the moon while the LEV carries crew and cargo to the lunar surface. Presented in the report are the mission analysis, systems layout, orbital mechanics, propulsion systems, structural and thermal analysis, and crew systems, avionics, and power systems for this lunar transportation concept.

  2. Heat transport system

    DOEpatents

    Pierce, Bill L.

    1978-01-01

    A heat transport system of small size which can be operated in any orientation consists of a coolant loop containing a vaporizable liquid as working fluid and includes in series a vaporizer, a condenser and two one-way valves and a pressurizer connected to the loop between the two valves. The pressurizer may be divided into two chambers by a flexible diaphragm, an inert gas in one chamber acting as a pneumatic spring for the system.

  3. Transportation Systems Center

    SciTech Connect

    Greer, G.S.

    1992-07-01

    The Transportation Systems Center at Sandia Laboratory performs research, development, and implementation of technologies that enhance the safe movement of people, goods, and information. Our focus is on systems engineering. However, we realize that to understand the puzzle, you must also understand the pieces. This brochure describes some of the activities currently underway at the Center and presents the breadth and depth of our capabilities. Please contact the noted, individuals for more, information.

  4. Competitive adsorption, displacement, and transport of organic matter on iron oxide: II. Displacement and transport

    NASA Astrophysics Data System (ADS)

    Gu, Baohua; Mehlhorn, Tonia L.; Liang, Liyuan; McCarthy, John F.

    1996-08-01

    The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salycylic acids. The transport of SR-NOM is found to involve a complex competitive interaction and displacement of different NOM subcomponents. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning

  5. Localization of Iron in Arabidopsis Seed Requires the Vacuolar Membrane Transporter VIT1

    SciTech Connect

    Kim,S.; Punshon, T.; Lanzirotti, A.; Li, L.; Alonso, J.; Ecker, J.; Kaplan, J.; Guerinot, M.

    2006-01-01

    Iron deficiency is a major human nutritional problem wherever plant-based diets are common. Using synchrotron x-ray fluorescence microtomography to directly visualize iron in Arabidopsis seeds, we show that iron is localized primarily to the provascular strands of the embryo. This localization is completely abolished when the vacuolar iron uptake transporter VIT1 is disrupted. Vacuolar iron storage is also critical for seedling development because vit1-1 seedlings grow poorly when iron is limiting. We have uncovered a fundamental aspect of seed biology that will ultimately aid the development of nutrient-rich seed, benefiting both human health and agricultural productivity.

  6. Role of the Fur Regulon in Iron Transport in Bacillus subtilis

    PubMed Central

    Ollinger, Juliane; Song, Kyung-Bok; Antelmann, Haike; Hecker, Michael; Helmann, John D.

    2006-01-01

    The Bacillus subtilis ferric uptake regulator (Fur) protein mediates the iron-dependent repression of at least 20 operons encoding ∼40 genes. We investigated the physiological roles of Fur-regulated genes by the construction of null mutations in 14 transcription units known or predicted to function in siderophore biosynthesis or iron uptake. We demonstrate that ywbLMN, encoding an elemental iron uptake system orthologous to the copper oxidase-dependent Fe(III) uptake system of Saccharomyces cerevisiae, is essential for growth in low iron minimal medium lacking citric acid. 2,3-Dihydroxybenzoyl-glycine (Itoic acid), the siderophore precursor produced by laboratory strains of B. subtilis, is of secondary importance. In the presence of citrate, the YfmCDEF ABC transporter is required for optimal growth. B. subtilis is unable to grow in minimal medium containing the iron chelator EDDHA unless the ability to synthesize the intact bacillibactin siderophore is restored (by the introduction of a functional sfp gene) or exogenous siderophores are provided. Utilization of the catecholate siderophores bacillibactin and enterobactin requires the FeuABC importer and the YusV ATPase. Utilization of hydroxamate siderophores requires the FhuBGC ABC transporter together with the FhuD (ferrichrome) or YxeB (ferrioxamine) substrate-binding proteins. Growth with schizokinen or arthrobactin is at least partially dependent on the YfhA YfiYZ importer and the YusV ATPase. We have also investigated the effects of a fur mutation on the proteome and documented the derepression of 11 Fur-regulated proteins, including a newly identified thioredoxin reductase homolog, YcgT. PMID:16672620

  7. Competitive adsorption, displacement, and transport of organic matter on iron oxide: II. Displacement and transport

    SciTech Connect

    Gu, B; Mehlhorn, T.L.; Liang, Liyuan

    1996-08-01

    The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salicylic acids. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning and transport. 37 refs., 10 figs.

  8. SUBSURFACE EMPLACEMENT TRANSPORTATION SYSTEM

    SciTech Connect

    T. Wilson; R. Novotny

    1999-11-22

    The objective of this analysis is to identify issues and criteria that apply to the design of the Subsurface Emplacement Transportation System (SET). The SET consists of the track used by the waste package handling equipment, the conductors and related equipment used to supply electrical power to that equipment, and the instrumentation and controls used to monitor and operate those track and power supply systems. Major considerations of this analysis include: (1) Operational life of the SET; (2) Geometric constraints on the track layout; (3) Operating loads on the track; (4) Environmentally induced loads on the track; (5) Power supply (electrification) requirements; and (6) Instrumentation and control requirements. This analysis will provide the basis for development of the system description document (SDD) for the SET. This analysis also defines the interfaces that need to be considered in the design of the SET. These interfaces include, but are not limited to, the following: (1) Waste handling building; (2) Monitored Geologic Repository (MGR) surface site layout; (3) Waste Emplacement System (WES); (4) Waste Retrieval System (WRS); (5) Ground Control System (GCS); (6) Ex-Container System (XCS); (7) Subsurface Electrical Distribution System (SED); (8) MGR Operations Monitoring and Control System (OMC); (9) Subsurface Facility System (SFS); (10) Subsurface Fire Protection System (SFR); (11) Performance Confirmation Emplacement Drift Monitoring System (PCM); and (12) Backfill Emplacement System (BES).

  9. Two iron-regulated transporter (IRT) genes showed differential expression in poplar trees under iron or zinc deficiency.

    PubMed

    Huang, Danqiong; Dai, Wenhao

    2015-08-15

    Two iron-regulated transporter (IRT) genes were cloned from the iron chlorosis resistant (PtG) and susceptible (PtY) Populus tremula 'Erecta' lines. Nucleotide sequence analysis showed no significant difference between PtG and PtY. The predicted proteins contain a conserved ZIP domain with 8 transmembrane (TM) regions. A ZIP signature sequence was found in the fourth TM domain. Phylogenetic analysis revealed that PtIRT1 was clustered with tomato and tobacco IRT genes that are highly responsible to iron deficiency. The PtIRT3 gene was clustered with the AtIRT3 gene that was related to zinc and iron transport in plants. Tissue specific expression indicated that PtIRT1 only expressed in the root, while PtIRT3 constitutively expressed in all tested tissues. Under iron deficiency, the expression of PtIRT1 was dramatically increased and a significantly higher transcript level was detected in PtG than in PtY. Iron deficiency also enhanced the expression of PtIRT3 in PtG. On the other hand, zinc deficiency down-regulated the expression of PtIRT1 and PtIRT3 in both PtG and PtY. Zinc accumulated significantly under iron-deficient conditions, whereas the zinc deficiency showed no significant effect on iron accumulation. A yeast complementation test revealed that the PtIRT1 and PtIRT3 genes could restore the iron uptake ability under the iron uptake-deficiency condition. The results will help understand the mechanisms of iron deficiency response in poplar trees and other woody species.

  10. Mars Equipment Transport System

    NASA Technical Reports Server (NTRS)

    Sorrells, Cindy; Geiger, Michelle; Ohanlon, Sean; Pieloch, Stuart; Brogan, Nick

    1993-01-01

    Mechanical Engineering Senior Design Project 1 (ME4182) is a part of the NASA/University Advanced Design Program. Under this program, NASA allocates money and resources to students to be used in design work for a specified topic. The current topic is the exploration and colonization of Mars. The specific area in which we are to work is the transportation of the modules in which astronauts will live while on Mars. NASA is concerned about the weight of the module transferring system, as the shipping cost to Mars is quite expensive. NASA has specified that the weight of the system is to be minimized in order to reduce the shipping costs.

  11. Mars Equipment Transport System

    NASA Astrophysics Data System (ADS)

    Sorrells, Cindy; Geiger, Michelle; Ohanlon, Sean; Pieloch, Stuart; Brogan, Nick

    1993-12-01

    Mechanical Engineering Senior Design Project 1 (ME4182) is a part of the NASA/University Advanced Design Program. Under this program, NASA allocates money and resources to students to be used in design work for a specified topic. The current topic is the exploration and colonization of Mars. The specific area in which we are to work is the transportation of the modules in which astronauts will live while on Mars. NASA is concerned about the weight of the module transferring system, as the shipping cost to Mars is quite expensive. NASA has specified that the weight of the system is to be minimized in order to reduce the shipping costs.

  12. Space Transportation Systems Technologies

    NASA Technical Reports Server (NTRS)

    Laue, Jay H.

    2001-01-01

    This document is the final report by the Science Applications International Corporation (SAIC) on contracted support provided to the National Aeronautics and Space Administration (NASA) under Contract NAS8-99060, 'Space Transportation Systems Technologies'. This contract, initiated by NASA's Marshall Space Flight Center (MSFC) on February 8, 1999, was focused on space systems technologies that directly support NASA's space flight goals. It was awarded as a Cost-Plus-Incentive-Fee (CPIF) contract to SAIC, following a competitive procurement via NASA Research Announcement, NRA 8-21. This NRA was specifically focused on tasks related to Reusable Launch Vehicles (RLVs). Through Task Area 3 (TA-3), "Other Related Technology" of this NRA contract, SAIC extensively supported the Space Transportation Directorate of MSFC in effectively directing, integrating, and setting its mission, operations, and safety priorities for future RLV-focused space flight. Following an initially contracted Base Year (February 8, 1999 through September 30, 1999), two option years were added to the contract. These were Option Year 1 (October 1, 1999 through September 30, 2000) and Option Year 2 (October 1, 2000 through September 30, 2001). This report overviews SAIC's accomplishments for the Base Year, Option Year 1, and Option Year 2, and summarizes the support provided by SAIC to the Space Transportation Directorate, NASA/MSFC.

  13. Mars transportation system

    NASA Technical Reports Server (NTRS)

    Garrard, William; Vano, Andrew; Rutherford, Dave

    1992-01-01

    The University of Minnesota Advanced Space Design Program has developed a sample Mars exploration scenario. The purpose of the design project is to enhance NASA and university interaction, to provide fresh ideas to NASA, and to provide real world design problems to engineering students. The Mars Transportation System in this paper is designed to transport a crew of six astronauts to the Martian surface and return them to Low Earth Orbit (LEO) starting in the year 2016. The proposed vehicle features such advanced technologies as nuclear propulsion, nuclear power generation, and aerobraking. Three missions are planned. Orbital trajectories are of the conjunction class with an inbound Venus swingby providing a 60-day surface stay at Mars and an average total trip time of 520 days.

  14. IRON REMOVAL PROCESSES: DESIGN OF NEW SYSTEMS

    EPA Science Inventory

    The recently promulgated Arsenic Rule will require that many new drinking water systems treat their water to remove arsenic. Many groundwaters that have arsenic in their source water also have iron in their water. As a result, arsenic treatment at these sites will most likely b...

  15. Chloroplast Iron Transport Proteins – Function and Impact on Plant Physiology

    PubMed Central

    López-Millán, Ana F.; Duy, Daniela; Philippar, Katrin

    2016-01-01

    Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today’s cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field. PMID:27014281

  16. A Golgi-localized MATE transporter mediates iron homoeostasis under osmotic stress in Arabidopsis.

    PubMed

    Seo, Pil Joon; Park, Jungmin; Park, Mi-Jeong; Kim, Youn-Sung; Kim, Sang-Gyu; Jung, Jae-Hoon; Park, Chung-Mo

    2012-03-15

    Iron is an essential micronutrient that acts as a cofactor in a wide variety of pivotal metabolic processes, such as the electron transport chain of respiration, photosynthesis and redox reactions, in plants. However, its overload exceeding the cellular capacity of iron binding and storage is potentially toxic to plant cells by causing oxidative stress and cell death. Consequently, plants have developed versatile mechanisms to maintain iron homoeostasis. Organismal iron content is tightly regulated at the steps of uptake, translocation and compartmentalization. Whereas iron uptake is fairly well understood at the cellular and organismal levels, intracellular and intercellular transport is only poorly understood. In the present study, we show that a MATE (multidrug and toxic compound extrusion) transporter, designated BCD1 (BUSH-AND-CHLOROTIC-DWARF 1), contributes to iron homoeostasis during stress responses and senescence in Arabidopsis. The BCD1 gene is induced by excessive iron, but repressed by iron deficiency. It is also induced by cellular and tissue damage occurring under osmotic stress. The activation-tagged mutant bcd1-1D exhibits leaf chlorosis, a typical symptom of iron deficiency. The chlorotic lesion of the mutant was partially recovered by iron feeding. Whereas the bcd1-1D mutant accumulated a lower amount of iron, the iron level was elevated in the knockout mutant bcd1-1. The BCD1 protein is localized to the Golgi complex. We propose that the BCD1 transporter plays a role in sustaining iron homoeostasis by reallocating excess iron released from stress-induced cellular damage.

  17. The Arabidopsis YELLOW STRIPE LIKE4 and 6 transporters control iron release from the chloroplast.

    PubMed

    Divol, Fanchon; Couch, Daniel; Conéjéro, Geneviève; Roschzttardtz, Hannetz; Mari, Stéphane; Curie, Catherine

    2013-03-01

    In most plant cell types, the chloroplast represents the largest sink for iron, which is both essential for chloroplast metabolism and prone to cause oxidative damage. Here, we show that to buffer the potentially harmful effects of iron, besides ferritins for storage, the chloroplast is equipped with specific iron transporters that respond to iron toxicity by removing iron from the chloroplast. We describe two transporters of the YELLOW STRIPE1-LIKE family from Arabidopsis thaliana, YSL4 and YSL6, which are likely to fulfill this function. Knocking out both YSL4 and YSL6 greatly reduces the plant's ability to cope with excess iron. Biochemical and immunolocalization analyses showed that YSL6 resides in the chloroplast envelope. Elemental analysis and histochemical staining indicate that iron is trapped in the chloroplasts of the ysl4 ysl6 double mutants, which also accumulate ferritins. Also, vacuolar iron remobilization and NRAMP3/4 expression are inhibited. Furthermore, ubiquitous expression of YSL4 or YSL6 dramatically reduces plant tolerance to iron deficiency and decreases chloroplastic iron content. These data demonstrate a fundamental role for YSL4 and YSL6 in managing chloroplastic iron. YSL4 and YSL6 expression patterns support their physiological role in detoxifying iron during plastid dedifferentiation occurring in embryogenesis and senescence.

  18. Analysis of high iron rice lines reveals new miRNAs that target iron transporters in roots

    PubMed Central

    Paul, Soumitra; Gayen, Dipak; Datta, Swapan K.; Datta, Karabi

    2016-01-01

    The present study highlights the molecular regulation of iron transport in soyFER1-overexpressing transgenic rice. Accumulation of iron in three different seed developmental stages, milk, dough, and mature, has been examined. The transgenic seeds of the milk stage showed significant augmentation of iron and zinc levels compared with wild-type seeds, and similar results were observed throughout the dough and mature stages. To investigate the regulation of iron transport, the role of miRNAs was studied in roots of transgenic rice. Sequencing of small RNA libraries revealed 153 known and 41 novel miRNAs in roots. Among them, 59 known and 14 novel miRNAs were found to be significantly expressed. miR166, miR399, and miR408 were identified as playing a vital role in iron uptake in roots of transgenic plants . Most importantly, four putative novel miRNAs, namely miR11, miR26, miR30, and miR31, were found to be down-regulated in roots of transgenic plants. For all these four novel miRNAs, natural resistance-associated macrophage protein 4 (NRAMP4), encoding a metal transporter, was predicted as a target gene. It is hypothesized that the NRAMP4 transporter is activated in roots of transgenic plants due to the lower abundance of its corresponding putative novel miRNAs. The relative transcript level of the NRAMP4 transcript was increased from 0.107 in the wild type to 65.24 and 55.39 in transgenic plants, which demonstrates the elevated amount of iron transport in transgenic plants. In addition, up-regulation of OsYSL15, OsFRO2, and OsIRT1 in roots also facilitates iron loading in transgenic seeds. PMID:27729476

  19. Specific expression of the vacuolar iron transporter, TgVit, causes iron accumulation in blue-colored inner bottom segments of various tulip petals.

    PubMed

    Momonoi, Kazumi; Tsuji, Toshiaki; Kazuma, Kohei; Yoshida, Kumi

    2012-01-01

    Several flowers of Tulipa gesneriana exhibit a blue color in the bottom segments of the inner perianth. We have previously reported the inner-bottom tissue-specific iron accumulation and expression of the vacuolar iron transporter, TgVit1, in tulip cv. Murasakizuisho. To clarify whether the TgVit1-dependent iron accumulation and blue-color development in tulip petals are universal, we analyzed anthocyanin, its co-pigment components, iron contents and the expression of TgVit1 mRNA in 13 cultivars which show a blue color in the bottom segments of the inner perianth accompanying yellow- and white-colored inner-bottom petals. All of the blue bottom segments contained the same anthocyanin component, delphinidin 3-rutinoside. The flavonol composition varied with cultivar and tissue part. The major flavonol in the bottom segments of the inner perianth was rutin. The iron content in the upper part was less than that in the bottom segments of the inner perianth. The iron content in the yellow and white petals was higher in the bottom segment of the inner perianth than in the upper tissues. TgVit1 mRNA expression was apparent in all of the bottom tissues of the inner perianth. The result of a reproduction experiment by mixing the constituents suggests that the blue coloration in tulip petals is generally caused by iron complexation to delphinidin 3-rutinoside and that the iron complex is solubilized and stabilized by flavonol glycosides. TgVit1-dependent iron accumulation in the bottom segments of the inner perianth might be controlled by an unknown system that differentiated the upper parts and bottom segments of the inner perianth. PMID:22313773

  20. Specific expression of the vacuolar iron transporter, TgVit, causes iron accumulation in blue-colored inner bottom segments of various tulip petals.

    PubMed

    Momonoi, Kazumi; Tsuji, Toshiaki; Kazuma, Kohei; Yoshida, Kumi

    2012-01-01

    Several flowers of Tulipa gesneriana exhibit a blue color in the bottom segments of the inner perianth. We have previously reported the inner-bottom tissue-specific iron accumulation and expression of the vacuolar iron transporter, TgVit1, in tulip cv. Murasakizuisho. To clarify whether the TgVit1-dependent iron accumulation and blue-color development in tulip petals are universal, we analyzed anthocyanin, its co-pigment components, iron contents and the expression of TgVit1 mRNA in 13 cultivars which show a blue color in the bottom segments of the inner perianth accompanying yellow- and white-colored inner-bottom petals. All of the blue bottom segments contained the same anthocyanin component, delphinidin 3-rutinoside. The flavonol composition varied with cultivar and tissue part. The major flavonol in the bottom segments of the inner perianth was rutin. The iron content in the upper part was less than that in the bottom segments of the inner perianth. The iron content in the yellow and white petals was higher in the bottom segment of the inner perianth than in the upper tissues. TgVit1 mRNA expression was apparent in all of the bottom tissues of the inner perianth. The result of a reproduction experiment by mixing the constituents suggests that the blue coloration in tulip petals is generally caused by iron complexation to delphinidin 3-rutinoside and that the iron complex is solubilized and stabilized by flavonol glycosides. TgVit1-dependent iron accumulation in the bottom segments of the inner perianth might be controlled by an unknown system that differentiated the upper parts and bottom segments of the inner perianth.

  1. Alternate transportation system

    NASA Technical Reports Server (NTRS)

    Zertuche, Tony; Mckinnie, James

    1988-01-01

    Three missions have been identified by NASA for a Space Shuttle-supplementing Alternate Transportation System (ATS) encompassing combinations of booster vehicles, crew modules, and service modules: (1) to achieve manned access to orbit for Space Station crew rotation every 90 days, (2) the lofting of a logistics module resupplying the Space Station every 180 days, and (3) the simultaneous launch of both crews and logistics to the Space Station. A reentry glider is considered, in conjunction with the Space Shuttle's unmanned cargo version and the Apollo manned capsule, as an important ATS element. The Titan IV/NUS is used as a booster.

  2. Characterization of a Dipartite Iron Uptake System from Uropathogenic Escherichia coli Strain F11*

    PubMed Central

    Koch, Doreen; Chan, Anson C. K.; Murphy, Michael E. P.; Lilie, Hauke; Grass, Gregor; Nies, Dietrich H.

    2011-01-01

    In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His44, Met90, His97, and His127, and CuB, a second degenerate octahedral geometry with the addition of Glu46. The copper ions of each site occupy distinct positions and are separated by ∼1.3 Å. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein. PMID:21596746

  3. Surface Complexation of Actinides with Iron Oxides: Implications for Radionuclide Transport in Near-Surface Aquifers

    NASA Astrophysics Data System (ADS)

    Jerden, J. L.; Kropf, A. J.; Tsai, Y.

    2005-12-01

    The surface complexation of actinides with iron oxides plays a key role in actinide transport and retardation in geosphere-biosphere systems. The development of accurate actinide transport models therefore requires a mechanistic understanding of surface complexation reactions (i.e. knowledge of chemical speciation at mineral/fluid interfaces). Iron oxides are particularly important actinide sorbents due to their pH dependent surface charges, relatively high surface areas and ubiquity in oxic and suboxic near-surface systems. In this paper we present results from field and laboratory investigations that elucidate the mechanisms involved in binding uranium and neptunium to iron oxide mineral substrates in near neutral groundwaters. The field study involved sampling and characterizing uranium-bearing groundwaters and solids from a saprolite aquifer overlying an unmined uranium deposit in the Virginia Piedmont. The groundwaters were analyzed by inductively coupled mass spectrometry and ion chromatography and the aquifer solids were analyzed by electron microprobe. The laboratory study involved a series of batch sorption tests in which U(VI) and Np(V) were reacted with goethite, hematite and magnetite in simulated groundwaters. The pH, ionic strength, aging time, and sorbent/sorbate ratios were varied in these experiments. The oxidation state and coordination environment of neptunium in solutions and sorbents from the batch tests were characterized by X-ray absorption spectroscopy (XAS) at the Advanced Photon Source, Argonne National Laboratory. Results from this work indicate that, in oxidizing near-surface aquifers, the dissolved concentration of uranium may be limited to less than 30 parts per billion due to uptake by iron oxide mineral coatings and the precipitation of sparingly soluble U(VI) phosphate minerals. Results from the batch adsorption tests showed that, in near neutral groundwaters, a significant fraction of the uranium and neptunium adsorbed as strongly

  4. SURFACE COMPLEXATION OF ACTINIDES WITH IRON OXIDES: IMPLICATIONS FOR RADIONUCLIDE TRANSPORT IN NEAR-SURFACE AQUIFERS

    SciTech Connect

    J.L. Jerden Jr.; A.J. Kropf; Y. Tsai

    2005-08-25

    The surface complexation of actinides with iron oxides plays a key role in actinide transport and retardation in geosphere-biosphere systems. The development of accurate actinide transport models therefore requires a mechanistic understanding of surface complexation reactions (i.e. knowledge of chemical speciation at mineral/fluid interfaces). Iron oxides are particularly important actinide sorbents due to their pH dependent surface charges, relatively high surface areas and ubiquity in oxic and suboxic near-surface systems. In this paper we present results from field and laboratory investigations that elucidate the mechanisms involved in binding uranium and neptunium to iron oxide mineral substrates in near neutral groundwaters. The field study involved sampling and characterizing uranium-bearing groundwaters and solids from a saprolite aquifer overlying an unmined uranium deposit in the Virginia Piedmont. The groundwaters were analyzed by inductively coupled mass spectrometry and ion chromatography and the aquifer solids were analyzed by electron microprobe. The laboratory study involved a series of batch sorption tests in which U(VI) and Np(V) were reacted with goethite, hematite and magnetite in simulated groundwaters. The pH, ionic strength, aging time, and sorbent/sorbate ratios were varied in these experiments. The oxidation state and coordination environment of neptunium in solutions and sorbents from the batch tests were characterized by X-ray absorption spectroscopy (XAS) at the Advanced Photon Source, Argonne National Laboratory. Results from this work indicate that, in oxidizing near-surface aquifers, the dissolved concentration of uranium may be limited to less than 30 parts per billion due to uptake by iron oxide mineral coatings and the precipitation of sparingly soluble U(VI) phosphate minerals. Results from the batch adsorption tests showed that, in near neutral groundwaters, a significant fraction of the uranium and neptunium adsorbed as strongly

  5. Effects of electron correlations on transport properties of iron at Earth's core conditions.

    PubMed

    Zhang, Peng; Cohen, R E; Haule, K

    2015-01-29

    Earth's magnetic field has been thought to arise from thermal convection of molten iron alloy in the outer core, but recent density functional theory calculations have suggested that the conductivity of iron is too high to support thermal convection, resulting in the investigation of chemically driven convection. These calculations for resistivity were based on electron-phonon scattering. Here we apply self-consistent density functional theory plus dynamical mean-field theory (DFT + DMFT) to iron and find that at high temperatures electron-electron scattering is comparable to the electron-phonon scattering, bringing theory into agreement with experiments and solving the transport problem in Earth's core. The conventional thermal dynamo picture is safe. We find that electron-electron scattering of d electrons is important at high temperatures in transition metals, in contrast to textbook analyses since Mott, and that 4s electron contributions to transport are negligible, in contrast to numerous models used for over fifty years. The DFT+DMFT method should be applicable to other high-temperature systems where electron correlations are important.

  6. Electron transport in pure and substituted iron oxyhydroxides by small-polaron migration

    SciTech Connect

    Alexandrov, Vitali Y.; Rosso, Kevin M.

    2014-08-12

    Iron oxyhydroxides (FeOOH) are common crystalline forms of iron that play a critical role in technology and the natural environment via a variety of important reduction-oxidation reactions, including electrical semiconduction as an aspect. However, a basic understanding of the electron transport properties of these systems is still lacking. We examine the electron mobility in goethite (α-FeOOH), akaganéite (β-FeOOH), and lepidocrocite (γ -FeOOH) polymorphs by means of density functional theory based (DFT+U) calculations.We show that room temperature charge transport should be dominated by the small-polaron hopping type, and that the attendant mobility should be highest for pure goethite and akaganéite. Hopping pathways through the various lattices are discussed in terms of individual electron exchange steps and rates for each. Given the usual occurrence of compositional impurities in natural iron oxyhydroxides, we also investigate the effect of common stoichiometric defects on the electron hopping activation energies such as Al and Cr substitutional cations in goethite, and Cl anions in the channels of akaganéite.

  7. Electron transport in pure and substituted iron oxyhydroxides by small-polaron migration

    SciTech Connect

    Alexandrov, Vitaly Rosso, Kevin M.

    2014-06-21

    Iron oxyhydroxides (FeOOH) are common crystalline forms of iron that play a critical role in technology and the natural environment via a variety of important reduction-oxidation reactions, including electrical semiconduction as an aspect. However, a basic understanding of the electron transport properties of these systems is still lacking. We examine the electron mobility in goethite (α-FeOOH), akaganéite (β-FeOOH), and lepidocrocite (γ-FeOOH) polymorphs by means of density functional theory based (DFT+U) calculations. We show that room temperature charge transport should be dominated by the small-polaron hopping type, and that the attendant mobility should be highest for pure goethite and akaganéite. Hopping pathways through the various lattices are discussed in terms of individual electron exchange steps and rates for each. Given the usual occurrence of compositional impurities in natural iron oxyhydroxides, we also investigate the effect of common stoichiometric defects on the electron hopping activation energies such as Al and Cr substitutional cations in goethite, and Cl anions in the channels of akaganéite.

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

    NASA Technical Reports Server (NTRS)

    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.

  9. New iron acquisition system in Bacteroidetes.

    PubMed

    Manfredi, Pablo; Lauber, Frédéric; Renzi, Francesco; Hack, Katrin; Hess, Estelle; Cornelis, Guy R

    2015-01-01

    Capnocytophaga canimorsus, a dog mouth commensal and a member of the Bacteroidetes phylum, causes rare but often fatal septicemia in humans that have been in contact with a dog. Here, we show that C. canimorsus strains isolated from human infections grow readily in heat-inactivated human serum and that this property depends on a typical polysaccharide utilization locus (PUL), namely, PUL3 in strain Cc5. PUL are a hallmark of Bacteroidetes, and they encode various products, including surface protein complexes that capture and process polysaccharides or glycoproteins. The archetype system is the Bacteroides thetaiotaomicron Sus system, devoted to starch utilization. Unexpectedly, PUL3 conferred the capacity to acquire iron from serotransferrin (STF), and this capacity required each of the seven encoded proteins, indicating that a whole Sus-like machinery is acting as an iron capture system (ICS), a new and unexpected function for Sus-like machinery. No siderophore could be detected in the culture supernatant of C. canimorsus, suggesting that the Sus-like machinery captures iron directly from transferrin, but this could not be formally demonstrated. The seven genes of the ICS were found in the genomes of several opportunistic pathogens from the Capnocytophaga and Prevotella genera, in different isolates of the severe poultry pathogen Riemerella anatipestifer, and in strains of Bacteroides fragilis and Odoribacter splanchnicus isolated from human infections. Thus, this study describes a new type of ICS that evolved in Bacteroidetes from a polysaccharide utilization system and most likely represents an important virulence factor in this group.

  10. New iron acquisition system in Bacteroidetes.

    PubMed

    Manfredi, Pablo; Lauber, Frédéric; Renzi, Francesco; Hack, Katrin; Hess, Estelle; Cornelis, Guy R

    2015-01-01

    Capnocytophaga canimorsus, a dog mouth commensal and a member of the Bacteroidetes phylum, causes rare but often fatal septicemia in humans that have been in contact with a dog. Here, we show that C. canimorsus strains isolated from human infections grow readily in heat-inactivated human serum and that this property depends on a typical polysaccharide utilization locus (PUL), namely, PUL3 in strain Cc5. PUL are a hallmark of Bacteroidetes, and they encode various products, including surface protein complexes that capture and process polysaccharides or glycoproteins. The archetype system is the Bacteroides thetaiotaomicron Sus system, devoted to starch utilization. Unexpectedly, PUL3 conferred the capacity to acquire iron from serotransferrin (STF), and this capacity required each of the seven encoded proteins, indicating that a whole Sus-like machinery is acting as an iron capture system (ICS), a new and unexpected function for Sus-like machinery. No siderophore could be detected in the culture supernatant of C. canimorsus, suggesting that the Sus-like machinery captures iron directly from transferrin, but this could not be formally demonstrated. The seven genes of the ICS were found in the genomes of several opportunistic pathogens from the Capnocytophaga and Prevotella genera, in different isolates of the severe poultry pathogen Riemerella anatipestifer, and in strains of Bacteroides fragilis and Odoribacter splanchnicus isolated from human infections. Thus, this study describes a new type of ICS that evolved in Bacteroidetes from a polysaccharide utilization system and most likely represents an important virulence factor in this group. PMID:25368114

  11. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    NASA Astrophysics Data System (ADS)

    Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

    2016-11-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

  12. Transportation System Concept of Operations

    SciTech Connect

    N. Slater-Thompson

    2006-08-16

    The Nuclear Waste Policy Act of 1982 (NWPA), as amended, authorized the DOE to develop and manage a Federal system for the disposal of SNF and HLW. OCRWM was created to manage acceptance and disposal of SNF and HLW in a manner that protects public health, safety, and the environment; enhances national and energy security; and merits public confidence. This responsibility includes managing the transportation of SNF and HLW from origin sites to the Repository for disposal. The Transportation System Concept of Operations is the core high-level OCRWM document written to describe the Transportation System integrated design and present the vision, mission, and goals for Transportation System operations. By defining the functions, processes, and critical interfaces of this system early in the system development phase, programmatic risks are minimized, system costs are contained, and system operations are better managed, safer, and more secure. This document also facilitates discussions and understanding among parties responsible for the design, development, and operation of the Transportation System. Such understanding is important for the timely development of system requirements and identification of system interfaces. Information provided in the Transportation System Concept of Operations includes: the functions and key components of the Transportation System; system component interactions; flows of information within the system; the general operating sequences; and the internal and external factors affecting transportation operations. The Transportation System Concept of Operations reflects OCRWM's overall waste management system policies and mission objectives, and as such provides a description of the preferred state of system operation. The description of general Transportation System operating functions in the Transportation System Concept of Operations is the first step in the OCRWM systems engineering process, establishing the starting point for the lower level

  13. Proceedings: 2002 Workshop on Pressurized Water Reactor Elevated Feedwater Iron Transport

    SciTech Connect

    2002-11-01

    Some pressurized water reactor (PWR) stations have experienced difficulty with maintaining feedwater (FW) iron concentrations below recommended concentration on a regular basis. A workshop held on September 17-18 in Dana Point, California, addressed the challenge of elevated feedwater iron transport in PWRs.

  14. Hereditary causes of disturbed iron homeostasis in the central nervous system.

    PubMed

    Ponka, Prem

    2004-03-01

    Iron is essential for oxidation-reduction catalysis and bioenergetics; however, unless appropriately shielded, this metal plays a crucial role in the formation of toxic oxygen radicals that can attack all biological molecules. Organisms are equipped with specific proteins designed for iron acquisition, export and transport, and storage, as well as with sophisticated mechanisms that maintain the intracellular labile iron pool at an appropriate level. Despite these homeostatic mechanisms, organisms often face the threat of either iron deficiency or iron overload. This review describes several hereditary iron-overloading conditions that are confined to the brain. Recently, a mutation in the L-subunit of ferritin has been described that causes the formation of aberrant L-ferritin with an altered C-terminus. Individuals with this mutation in one allele of L-ferritin have abnormal aggregates of ferritin and iron in the brain, primarily in the globus pallidus. Patients with this dominantly inherited late-onset disease present with symptoms of extrapyramidal dysfunction. Mice with a targeted disruption of a gene for iron regulatory protein 2 (IRP2), a translational repressor of ferritin, misregulate iron metabolism in the intestinal mucosa and the central nervous system. Significant amounts of ferritin and iron accumulate in white matter tracts and nuclei, and adult IRP2-deficient mice develop a movement disorder consisting of ataxia, bradykinesia, and tremor. Mutations in the frataxin gene are responsible for Friedreich's ataxia, the most common of the inherited ataxias. Frataxin appears to regulate mitochondrial iron-sulfur cluster formation, and the neurologic and cardiac manifestations of Friedreich's ataxia are due to iron-mediated mitochondrial toxicity. Patients with Hallervorden-Spatz syndrome, an autosomal recessive, progressive neurodegenerative disorder, have mutations in a novel pantothenate kinase gene (PANK2). The cardinal feature of this extrapyramidal

  15. The Siderocalin/Enterobactin Interaction: a Link Between Mammalian Immunity And Bacterial Iron Transport

    SciTech Connect

    Abergel, R.J.; Clifton, M.C.; Pizarro, J.C.; Warner, J.A.; Shuh, D.K.; Strong, R.K.; Raymond, K.N.

    2009-05-12

    The siderophore enterobactin (Ent) is produced by enteric bacteria to mediate iron uptake. Ent scavenges iron and is taken up by the bacteria as the highly stable ferric complex [Fe{sup III}(Ent)]{sup 3-}. This complex is also a specific target of the mammalian innate immune system protein, Siderocalin (Scn), which acts as an antibacterial agent by specifically sequestering siderophores and their ferric complexes during infection. Recent literature suggesting that Scn may also be involved in cellular iron transport has increased the importance of understanding the mechanism of siderophore interception and clearance by Scn; Scn is observed to release iron in acidic endosomes and [Fe{sup III}(Ent)]{sup 3-} is known to undergo a change from catecholate to salicylate coordination in acidic conditions, which is predicted to be sterically incompatible with the Scn binding pocket (also referred to as the calyx). To investigate the interactions between the ferric Ent complex and Scn at different pH values, two recombinant forms of Scn with mutations in three residues lining the calyx were prepared: Scn-W79A/R81A and Scn-Y106F. Binding studies and crystal structures of the Scn-W79A/R81A:[Fe{sup III}(Ent)]{sup 3-} and Scn-Y106F:[Fe{sup III}(Ent)]{sup 3-} complexes confirm that such mutations do not affect the overall conformation of the protein but do weaken significantly its affinity for [Fe{sup III}(Ent)]{sup 3-}. Fluorescence, UV-vis, and EXAFS spectroscopies were used to determine Scn/siderophore dissociation constants and to characterize the coordination mode of iron over a wide pH range, in the presence of both mutant proteins and synthetic salicylate analogues of Ent. While Scn binding hinders salicylate coordination transformation, strong acidification results in the release of iron and degraded siderophore. Iron release may therefore result from a combination of Ent degradation and coordination change.

  16. The Siderocalin/Enterobactin Interaction: A Link between Mammalian Immunity and Bacterial Iron Transport

    SciTech Connect

    Meux, Susan C.

    2008-05-12

    The siderophore enterobactin (Ent) is produced by enteric bacteria to mediate iron uptake. Ent scavenges iron and is taken up by the bacteria as the highly stable ferric complex [Fe{sup III}(Ent)]{sup 3-}. This complex is also a specific target of the mammalian innate immune system protein, Siderocalin (Scn), which acts as an anti-bacterial agent by specifically sequestering siderophores and their ferric complexes during infection. Recent literature suggesting that Scn may also be involved in cellular iron transport has increased the importance of understanding the mechanism of siderophore interception and clearance by Scn; Scn is observed to release iron in acidic endosomes and [Fe{sup III}(Ent)]{sup 3-} is known to undergo a change from catecholate to salicylate coordination in acidic conditions, which is predicted to be sterically incompatible with the Scn binding pocket (also referred to as the calyx). To investigate the interactions between the ferric Ent complex and Scn at different pH values, two recombinant forms of Scn with mutations in three residues lining the calyx were prepared: Scn-W79A/R81A and Scn-Y106F. Binding studies and crystal structures of the Scn-W79A/R81A:[Fe{sup III}(Ent)]{sup 3-} and Scn-Y106F:[Fe{sup III}(Ent)]{sup 3-} complexes confirm that such mutations do not affect the overall conformation of the protein but do weaken significantly its affinity for [Fe{sup III}(Ent)]{sup 3-}. Fluorescence, UV-Vis and EXAFS spectroscopies were used to determine Scn/siderophore dissociation constants and to characterize the coordination mode of iron over a wide pH range, in the presence of both mutant proteins and synthetic salicylate analogs of Ent. While Scn binding hinders salicylate coordination transformation, strong acidification results in the release of iron and degraded siderophore. Iron release may therefore result from a combination of Ent degradation and coordination change.

  17. Reactive transport modeling at uranium in situ recovery sites: uncertainties in uranium sorption on iron hydroxides

    USGS Publications Warehouse

    Johnson, Raymond H.; Tutu, Hlanganani; Brown, Adrian; Figueroa, Linda; Wolkersdorfer, Christian

    2013-01-01

    Geochemical changes that can occur down gradient from uranium in situ recovery (ISR) sites are important for various stakeholders to understand when evaluating potential effects on surrounding groundwater quality. If down gradient solid-phase material consists of sandstone with iron hydroxide coatings (no pyrite or organic carbon), sorption of uranium on iron hydroxides can control uranium mobility. Using one-dimensional reactive transport models with PHREEQC, two different geochemical databases, and various geochemical parameters, the uncertainties in uranium sorption on iron hydroxides are evaluated, because these oxidized zones create a greater risk for future uranium transport than fully reduced zones where uranium generally precipitates.

  18. Iron transport in the kidney: implications for physiology and cadmium nephrotoxicity.

    PubMed

    Thévenod, Frank; Wolff, Natascha A

    2016-01-01

    The kidney has recently emerged as an organ with a significant role in systemic iron (Fe) homeostasis. Substantial amounts of Fe are filtered by the kidney, which have to be reabsorbed to prevent Fe deficiency. Accordingly Fe transporters and receptors for protein-bound Fe are expressed in the nephron that may also function as entry pathways for toxic metals, such as cadmium (Cd), by way of "ionic and molecular mimicry". Similarities, but also differences in handling of Cd by these transport routes offer rationales for the propensity of the kidney to develop Cd toxicity. This critical review provides a comprehensive update on Fe transport by the kidney and its relevance for physiology and Cd nephrotoxicity. Based on quantitative considerations, we have also estimated the in vivo relevance of the described transport pathways for physiology and toxicology. Under physiological conditions all segments of the kidney tubules are likely to utilize Fe for cellular Fe requiring processes for metabolic purposes and also to contribute to reabsorption of free and bound forms of Fe into the circulation. But Cd entering tubule cells disrupts metabolic pathways and is unable to exit. Furthermore, our quantitative analyses contest established models linking chronic Cd nephrotoxicity to proximal tubular uptake of metallothionein-bound Cd. Hence, Fe transport by the kidney may be beneficial by preventing losses from the body. But increased uptake of Fe or Cd that cannot exit tubule cells may lead to kidney injury, and Fe deficiency may facilitate renal Cd uptake.

  19. Role of clay minerals in the transportation of iron

    USGS Publications Warehouse

    Carroll, D.

    1958-01-01

    The clay minerals have iron associated with them in several ways: 1. (1) as an essential constituent 2. (2) as a minor constituent within the crystal lattice where it is in isomorphous substitution and 3. (3) as iron oxide on the surface of the mineral platelets. Nontronite, "hydromica," some chlorites, vermiculite, glauconite and chamosite contain iron as an essential constituent. Kaolinite and halloysite have no site within the lattice for iron, but in certain environments iron oxide (goethite or hematite) is intimately associated as a coating on the micelles. Analyses of clay minerals show that the content of Fe2O3 varies: 29 per cent (nontronite), 7??3 per cent (griffithite), 4.5 per cent ("hydromica"), 5.5 per cent (chlorite), 4 per cent (vermiculite) and 18 per cent (glauconite). The FeO content is: 40 per cent (chamosite), 7.8 per cent (griffithite), 1-2 per cent ("hydromica"), 3 per cent (glauconite) and 2 per cent (chlorite). The iron associated with the clay minerals remains stable in the environment in which the minerals occur, but if either pH or Eh or both are changed the iron may be affected. Change of environment will cause: 1. (1) removal of iron by reduction of Fe3+ to Fe2+; 2. (2) ion-exchange reactions; 3. (3) instability of the crystal lattice. Experiments using bacterial activity to produce reducing conditions with kaolinite and halloysite coated with iron oxides and with nontronite in which ferric iron is in the octahedral position within the lattice showed that ferric oxide is removed at Eh +0??215 in fresh water and at Eh +0.098 in sea water. Hematite, goethite, and indefinite iron oxides were removed at different rates. Red ferric oxides were changed to black indefinite noncrystalline ferrous sulphide at Eh -0.020 but reverted to ferric oxide under oxidizing conditions. Nontronite turned bright green under reducing conditions and some of the ferrous iron remained within the lattice on a return to oxidizing conditions. Bacterial activity

  20. Helium, Iron and Electron Particle Transport and Energy Transport Studies on the TFTR Tokamak

    DOE R&D Accomplishments Database

    Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))

    1993-03-01

    Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

  1. Helium, iron and electron particle transport and energy transport studies on the TFTR tokamak

    SciTech Connect

    Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Grek, B.; Hill, K.W.; Hulse, R.A.; Johnson, D.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Redi, M.H.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.; Kissick, M.W.

    1993-03-01

    Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

  2. Role of Iron Uptake Systems in Pseudomonas aeruginosa Virulence and Airway Infection.

    PubMed

    Minandri, Fabrizia; Imperi, Francesco; Frangipani, Emanuela; Bonchi, Carlo; Visaggio, Daniela; Facchini, Marcella; Pasquali, Paolo; Bragonzi, Alessandra; Visca, Paolo

    2016-08-01

    Pseudomonas aeruginosa is a leading cause of hospital-acquired pneumonia and chronic lung infections in cystic fibrosis patients. Iron is essential for bacterial growth, and P. aeruginosa expresses multiple iron uptake systems, whose role in lung infection deserves further investigation. P. aeruginosa Fe(3+) uptake systems include the pyoverdine and pyochelin siderophores and two systems for heme uptake, all of which are dependent on the TonB energy transducer. P. aeruginosa also has the FeoB transporter for Fe(2+) acquisition. To assess the roles of individual iron uptake systems in P. aeruginosa lung infection, single and double deletion mutants were generated in P. aeruginosa PAO1 and characterized in vitro, using iron-poor media and human serum, and in vivo, using a mouse model of lung infection. The iron uptake-null mutant (tonB1 feoB) and the Fe(3+) transport mutant (tonB1) did not grow aerobically under low-iron conditions and were avirulent in the mouse model. Conversely, the wild type and the feoB, hasR phuR (heme uptake), and pchD (pyochelin) mutants grew in vitro and caused 60 to 90% mortality in mice. The pyoverdine mutant (pvdA) and the siderophore-null mutant (pvdA pchD) grew aerobically in iron-poor media but not in human serum, and they caused low mortality in mice (10 to 20%). To differentiate the roles of pyoverdine in iron uptake and virulence regulation, a pvdA fpvR double mutant defective in pyoverdine production but expressing wild-type levels of pyoverdine-regulated virulence factors was generated. Deletion of fpvR in the pvdA background partially restored the lethal phenotype, indicating that pyoverdine contributes to the pathogenesis of P. aeruginosa lung infection by combining iron transport and virulence-inducing capabilities. PMID:27271740

  3. Role of Iron Uptake Systems in Pseudomonas aeruginosa Virulence and Airway Infection.

    PubMed

    Minandri, Fabrizia; Imperi, Francesco; Frangipani, Emanuela; Bonchi, Carlo; Visaggio, Daniela; Facchini, Marcella; Pasquali, Paolo; Bragonzi, Alessandra; Visca, Paolo

    2016-08-01

    Pseudomonas aeruginosa is a leading cause of hospital-acquired pneumonia and chronic lung infections in cystic fibrosis patients. Iron is essential for bacterial growth, and P. aeruginosa expresses multiple iron uptake systems, whose role in lung infection deserves further investigation. P. aeruginosa Fe(3+) uptake systems include the pyoverdine and pyochelin siderophores and two systems for heme uptake, all of which are dependent on the TonB energy transducer. P. aeruginosa also has the FeoB transporter for Fe(2+) acquisition. To assess the roles of individual iron uptake systems in P. aeruginosa lung infection, single and double deletion mutants were generated in P. aeruginosa PAO1 and characterized in vitro, using iron-poor media and human serum, and in vivo, using a mouse model of lung infection. The iron uptake-null mutant (tonB1 feoB) and the Fe(3+) transport mutant (tonB1) did not grow aerobically under low-iron conditions and were avirulent in the mouse model. Conversely, the wild type and the feoB, hasR phuR (heme uptake), and pchD (pyochelin) mutants grew in vitro and caused 60 to 90% mortality in mice. The pyoverdine mutant (pvdA) and the siderophore-null mutant (pvdA pchD) grew aerobically in iron-poor media but not in human serum, and they caused low mortality in mice (10 to 20%). To differentiate the roles of pyoverdine in iron uptake and virulence regulation, a pvdA fpvR double mutant defective in pyoverdine production but expressing wild-type levels of pyoverdine-regulated virulence factors was generated. Deletion of fpvR in the pvdA background partially restored the lethal phenotype, indicating that pyoverdine contributes to the pathogenesis of P. aeruginosa lung infection by combining iron transport and virulence-inducing capabilities.

  4. Iron and copper release in drinking-water distribution systems.

    PubMed

    Shi, Baoyou; Taylor, James S

    2007-09-01

    A large-scale pilot study was carried out to evaluate the impacts of changes in water source and treatment process on iron and copper release in water distribution systems. Finished surface waters, groundwaters, and desalinated waters were produced with seven different treatment systems and supplied to 18 pipe distribution systems (PDSs). The major water treatment processes included lime softening, ferric sulfate coagulation, reverse osmosis, nanofiltration, and integrated membrane systems. PDSs were constructed from PVC, lined cast iron, unlined cast iron, and galvanized pipes. Copper pipe loops were set up for corrosion monitoring. Results showed that surface water after ferric sulfate coagulation had low alkalinity and high sulfates, and consequently caused the highest iron release. Finished groundwater treated by conventional method produced the lowest iron release but the highest copper release. The iron release of desalinated water was relatively high because of the water's high chloride level and low alkalinity. Both iron and copper release behaviors were influenced by temperature.

  5. [Transport of dinitrosyl iron complexes into animal lungs].

    PubMed

    Mojokina, G N; Elistratova, N A; Mikoyan, V D; Vanin, A F

    2015-01-01

    Effective accumulation of binuclear dinitrosyl iron complexes with glutathione was shown after a subcutaneous para lymphatic injection of an aqueous solution of a dinitrosyl-iron complex into animal lung tissue at a single-dose of 2 micromoles per kilogram two times a day with a 2-h interval. Two hours later after the administration was repeated the concentration of these complexes was 16 micromoles per kilogram of tissue dropping down for the last two hours to 7 micromoles per kilogram of tissue. At one dose injection of binuclear dinitrosyl iron complexes with glutathione their concentration in 2 and 4 hours was two times lower than in the previous experiments. Presumably at the obtained concentration of dinitrosyl iron complexes a bactericidal effect in lungs can be observed against mycobacterium tuberculosis and rapidly proliferating lung tumors. PMID:26016033

  6. Iron transport across the blood-brain barrier; Development, neurovascular regulation and cerebral amyloid angiopathy

    PubMed Central

    McCarthy, Ryan C; Kosman, Daniel J

    2014-01-01

    There are two barriers for iron entry into the brain: 1) the brain-cerebrospinal fluid (CSF) barrier and 2) the blood-brain barrier (BBB). Here, we review the literature on developmental iron accumulation by the brain, focusing on the transport of iron through the brain microvascular endothelial cells (BMVEC) of the BBB. We review the iron trafficking proteins which may be involved in the iron flux across BMVEC and discuss the plausible mechanisms of BMVEC iron uptake and efflux. We suggest a model for how BMVEC iron uptake and efflux are regulated and a mechanism by which the majority of iron is trafficked across the developing BBB under the direct guidance of neighboring astrocytes. Thus, we place brain iron uptake in the context of the neurovascular unit of the adult brain. Last, we propose that BMVEC iron is involved in the aggregation of amyloid-β peptides leading to the progression of cerebral amyloid angiopathy which often occurs prior to dementia and the onset of Alzheimer's disease. PMID:25355056

  7. Transport of carbon colloid supported nanoscale zero-valent iron in saturated porous media.

    PubMed

    Busch, Jan; Meißner, Tobias; Potthoff, Annegret; Oswald, Sascha E

    2014-08-01

    Injection of nanoscale zero-valent iron (nZVI) has recently gained great interest as emerging technology for in-situ remediation of chlorinated organic compounds from groundwater systems. Zero-valent iron (ZVI) is able to reduce organic compounds and to render it to less harmful substances. The use of nanoscale particles instead of granular or microscale particles can increase dechlorination rates by orders of magnitude due to its high surface area. However, classical nZVI appears to be hampered in its environmental application by its limited mobility. One approach is colloid supported transport of nZVI, where the nZVI gets transported by a mobile colloid. In this study transport properties of activated carbon colloid supported nZVI (c-nZVI; d50=2.4μm) are investigated in column tests using columns of 40cm length, which were filled with porous media. A suspension was pumped through the column under different physicochemical conditions (addition of a polyanionic stabilizer and changes in pH and ionic strength). Highest observed breakthrough was 62% of the injected concentration in glass beads with addition of stabilizer. Addition of mono- and bivalent salt, e.g. more than 0.5mM/L CaCl2, can decrease mobility and changes in pH to values below six can inhibit mobility at all. Measurements of colloid sizes and zeta potentials show changes in the mean particle size by a factor of ten and an increase of zeta potential from -62mV to -80mV during the transport experiment. However, results suggest potential applicability of c-nZVI under field conditions.

  8. Iron, oxidative stress, and redox signaling in the cardiovascular system.

    PubMed

    Gudjoncik, Aurélie; Guenancia, Charles; Zeller, Marianne; Cottin, Yves; Vergely, Catherine; Rochette, Luc

    2014-08-01

    The redox state of the cell is predominantly dependent on an iron redox couple and is maintained within strict physiological limits. Iron is an essential metal for hemoglobin synthesis in erythrocytes, for oxidation-reduction reactions, and for cellular proliferation. The maintenance of stable iron concentrations requires the coordinated regulation of iron transport into plasma from dietary sources in the duodenum, from recycled senescent red cells in macrophages, and from storage in hepatocytes. The absorption of dietary iron, which is present in heme or nonheme form, is carried out by mature villus enterocytes of the duodenum and proximal jejunum. Multiple physiological processes are involved in maintaining iron homeostasis. These include its storage at the intracellular and extracellular level. Control of iron balance in the whole organism requires communication between sites of uptake, utilization, and storage. Key protein transporters and the molecules that regulate their activities have been identified. In this field, ferritins and hepcidin are the major regulator proteins. A variety of transcription factors may be activated depending on the level of oxidative stress, leading to the expression of different genes. Major preclinical and clinical trials have shown advances in iron-chelation therapy for the treatment of iron-overload disease as well as cardiovascular and chronic inflammatory diseases.

  9. Iron, oxidative stress, and redox signaling in the cardiovascular system.

    PubMed

    Gudjoncik, Aurélie; Guenancia, Charles; Zeller, Marianne; Cottin, Yves; Vergely, Catherine; Rochette, Luc

    2014-08-01

    The redox state of the cell is predominantly dependent on an iron redox couple and is maintained within strict physiological limits. Iron is an essential metal for hemoglobin synthesis in erythrocytes, for oxidation-reduction reactions, and for cellular proliferation. The maintenance of stable iron concentrations requires the coordinated regulation of iron transport into plasma from dietary sources in the duodenum, from recycled senescent red cells in macrophages, and from storage in hepatocytes. The absorption of dietary iron, which is present in heme or nonheme form, is carried out by mature villus enterocytes of the duodenum and proximal jejunum. Multiple physiological processes are involved in maintaining iron homeostasis. These include its storage at the intracellular and extracellular level. Control of iron balance in the whole organism requires communication between sites of uptake, utilization, and storage. Key protein transporters and the molecules that regulate their activities have been identified. In this field, ferritins and hepcidin are the major regulator proteins. A variety of transcription factors may be activated depending on the level of oxidative stress, leading to the expression of different genes. Major preclinical and clinical trials have shown advances in iron-chelation therapy for the treatment of iron-overload disease as well as cardiovascular and chronic inflammatory diseases. PMID:24888568

  10. Evaluation of the effect of divalent metal transporter 1 gene polymorphism on blood iron, lead and cadmium levels

    SciTech Connect

    Kayaaltı, Zeliha Akyüzlü, Dilek Kaya; Söylemezoğlu, Tülin

    2015-02-15

    Divalent metal transporter 1 (DMT1), a member of the proton-coupled metal ion transporter family, mediates transport of ferrous iron from the lumen of the intestine into the enterocyte and export of iron from endocytic vesicles. It has an affinity not only for iron but also for other divalent cations including manganese, cobalt, nickel, cadmium, lead, copper, and zinc. DMT1 is encoded by the SLC11a2 gene that is located on chromosome 12q13 in humans and express four major mammalian isoforms (1A/+IRE, 1A/-IRE, 2/+IRE and 2/-IRE). Mutations or polymorphisms of DMT1 gene may have an impact on human health by disturbing metal trafficking. To study the possible association of DMT1 gene with the blood levels of some divalent cations such as iron, lead and cadmium, a single nucleotide polymorphism (SNP) (IVS4+44C/A) in DMT1 gene was investigated in 486 unrelated and healthy individuals in a Turkish population by method of polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The genotype frequencies were found as 49.8% homozygote typical (CC), 38.3% heterozygote (CA) and 11.9% homozygote atypical (AA). Metal levels were analyzed by dual atomic absorption spectrometer system and the average levels of iron, lead and cadmium in the blood samples were 446.01±81.87 ppm, 35.59±17.72 ppb and 1.25±0.87 ppb, respectively. Individuals with the CC genotype had higher blood iron, lead and cadmium levels than those with AA and CA genotypes. Highly statistically significant associations were detected between IVS4+44 C/A polymorphism in the DMT1 gene and iron and lead levels (p=0.001 and p=0.036, respectively), but no association was found with cadmium level (p=0.344). This study suggested that DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, lead and cadmium levels. - Highlights: • DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, cadmium and lead levels.

  11. Nickel-iron battery system safety

    NASA Technical Reports Server (NTRS)

    Saltat, R. C.

    1984-01-01

    The generated flow rates of gaseous hydrogen and gaseous oxygen from an electrical vehicle nickel-iron battery system were determined and used to evaluate the flame quenching capabilities of several candidate devices to prevent flame propagation within batteries having central watering/venting systems. The battery generated hydrogen and oxygen gases were measured for a complete charge and discharge cycle. The data correlates well with accepted theory during strong overcharge conditions indicating that the measurements are valid for other portions of the cycle. Tests confirm that the gas mixture in the cells is always flammable regardless of the battery status. The literature indicated that a conventional flame arrestor would not be effective over the broad spectrum of gassing conditions presented by a nickel-iron battery. Four different types of protective devices were evaluated. A foam-metal arrestor design was successful in quenching gaseous hydrogen and gaseous oxygen flames, however; the application of this flame arrestor to individual cell or module protection in a battery is problematic. A possible rearrangement of the watering/venting system to accept the partial protection of simple one-way valves is presented which, in combination with the successful foam-metal arrestor as main vent protection, could result in a significant improvement in battery protection.

  12. Use of Electrophoresis for Transporting Nano-Iron in Porous Media

    EPA Science Inventory

    Research was conducted to evaluate if electrophoresis could transport surface stabilized nanoscale zero-valent iron (nZVI) through fine grained sand with the intent of remediating a contaminant in situ. The experimental procedure involved determining the transport rates of poly...

  13. MASS TRANSPORT EFFECTS ON THE KINETICS OF NITROBENZENE REDUCTION BY IRON METAL. (R827117)

    EPA Science Inventory

    To evaluate the importance of external mass transport on the overall rates of
    contaminant reduction by iron metal (Fe0), we have compared measured
    rates of surface reaction for nitrobenzene (ArNO2) to estimated rates
    of external mass transport...

  14. Iron

    MedlinePlus

    ... cereals and breads. White beans, lentils, spinach, kidney beans, and peas. Nuts and some dried fruits, such as raisins. Iron in food comes in two forms: heme iron and nonheme iron. Nonheme iron is found in plant foods and iron-fortified food products. Meat, seafood, ...

  15. Getting to the root of plant iron uptake and cell-cell transport: Polarity matters!

    PubMed

    Dubeaux, Guillaume; Zelazny, Enric; Vert, Grégory

    2015-01-01

    Plasma membrane proteins play pivotal roles in mediating responses to endogenous and environmental cues. Regulation of membrane protein levels and establishment of polarity are fundamental for many cellular processes. In plants, IRON-REGULATED TRANSPORTER 1 (IRT1) is the major root iron transporter but is also responsible for the absorption of other divalent metals such as manganese, zinc and cobalt. We recently uncovered that IRT1 is polarly localized to the outer plasma membrane domain of plant root epidermal cells upon depletion of its secondary metal substrates. The endosome-recruited FYVE1 protein interacts with IRT1 in the endocytic pathway and plays a crucial role in the establishment of IRT1 polarity, likely through its recycling to the cell surface. Our work sheds light on the mechanisms of radial transport of nutrients across the different cell types of plant roots toward the vascular tissues and raises interesting parallel with iron transport in mammals.

  16. Getting to the root of plant iron uptake and cell-cell transport: Polarity matters!

    PubMed

    Dubeaux, Guillaume; Zelazny, Enric; Vert, Grégory

    2015-01-01

    Plasma membrane proteins play pivotal roles in mediating responses to endogenous and environmental cues. Regulation of membrane protein levels and establishment of polarity are fundamental for many cellular processes. In plants, IRON-REGULATED TRANSPORTER 1 (IRT1) is the major root iron transporter but is also responsible for the absorption of other divalent metals such as manganese, zinc and cobalt. We recently uncovered that IRT1 is polarly localized to the outer plasma membrane domain of plant root epidermal cells upon depletion of its secondary metal substrates. The endosome-recruited FYVE1 protein interacts with IRT1 in the endocytic pathway and plays a crucial role in the establishment of IRT1 polarity, likely through its recycling to the cell surface. Our work sheds light on the mechanisms of radial transport of nutrients across the different cell types of plant roots toward the vascular tissues and raises interesting parallel with iron transport in mammals. PMID:26479146

  17. Iron

    MedlinePlus

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  18. Normal systemic iron homeostasis in mice with macrophage-specific deletion of transferrin receptor 2.

    PubMed

    Rishi, Gautam; Secondes, Eriza S; Wallace, Daniel F; Subramaniam, V Nathan

    2016-02-01

    Iron is an essential element, since it is a component of many macromolecules involved in diverse physiological and cellular functions, including oxygen transport, cellular growth, and metabolism. Systemic iron homeostasis is predominantly regulated by the liver through the iron regulatory hormone hepcidin. Hepcidin expression is itself regulated by a number of proteins, including transferrin receptor 2 (TFR2). TFR2 has been shown to be expressed in the liver, bone marrow, macrophages, and peripheral blood mononuclear cells. Studies from our laboratory have shown that mice with a hepatocyte-specific deletion of Tfr2 recapitulate the hemochromatosis phenotype of the global Tfr2 knockout mice, suggesting that the hepatic expression of TFR2 is important in systemic iron homeostasis. It is unclear how TFR2 in macrophages contributes to the regulation of iron metabolism. We examined the role of TFR2 in macrophages by analysis of transgenic mice lacking Tfr2 in macrophages by crossing Tfr2(f/f) mice with LysM-Cre mice. Mice were fed an iron-rich diet or injected with lipopolysaccharide to examine the role of macrophage Tfr2 in iron- or inflammation-mediated regulation of hepcidin. Body iron homeostasis was unaffected in the knockout mice, suggesting that macrophage TFR2 is not required for the regulation of systemic iron metabolism. However, peritoneal macrophages of knockout mice had significantly lower levels of ferroportin mRNA and protein, suggesting that TFR2 may be involved in regulating ferroportin levels in macrophages. These studies further elucidate the role of TFR2 in the regulation of iron homeostasis and its role in regulation of ferroportin and thus macrophage iron homeostasis.

  19. Transport characteristics of nanoscale functional zerovalent iron/silica composites for in situ remediation of trichloroethylene.

    PubMed

    Zhan, Jingjing; Zheng, Tonghua; Piringer, Gerhard; Day, Christopher; McPherson, Gary L; Lu, Yunfeng; Papadopoulos, Kyriakos; John, Vijay T

    2008-12-01

    Effective in situ remediation of groundwater requires the successful delivery of reactive iron particles through soil. In this paper we report the transport characteristics of nanoscale zerovalent iron entrapped in porous silica particles and prepared through an aerosol-assisted process. The entrapment of iron nanoparticles into the silica matrix prevents their aggregation while maintaining the particles' reactivity. Furthermore, the silica particles are functionalized with alkyl groups and are extremely efficient in adsorbing dissolved trichloroethylene (TCE). Because of synthesis through the aerosol route, the particles are of the optimal size range (0.1-1 microm) for mobility through sediments. Column and capillary transport experiments confirm that the particles move far more effectivelythrough model soils than commercially available uncoated nanoscale reactive iron particles. Microcapillary experiments indicate that the particles partition to the interface of TCE droplets, further enhancing their potential for dense non-aqueous-phase liquid source-zone remediation.

  20. Droplet transport system and methods

    NASA Technical Reports Server (NTRS)

    Neitzel, G. Paul (Inventor)

    2010-01-01

    Embodiments of droplet transport systems and methods are disclosed for levitating and transporting single or encapsulated droplets using thermocapillary convection. One method embodiment, among others comprises providing a droplet of a first liquid; and applying thermocapillary convection to the droplet to levitate and move the droplet.

  1. The ferrous iron transporter FtrABCD is required for the virulence of Brucella abortus 2308 in mice.

    PubMed

    Elhassanny, Ahmed E M; Anderson, Eric S; Menscher, Evan A; Roop, R Martin

    2013-06-01

    Iron transport has been linked to the virulence of Brucella strains in both natural and experimental hosts. The genes designated BAB2_0837-0840 in the Brucella abortus 2308 genome sequence are predicted to encode a CupII-type ferrous iron transporter homologous to the FtrABCD transporter recently described in Bordetella. To study the role of the Brucella FtrABCD in iron transport, an isogenic ftrA mutant was constructed from B. abortus 2308. Compared with the parental strain, the B. abortus ftrA mutant displays a decreased capacity to use non-haem iron sources in vitro, a growth defect in a low iron medium that is enhanced at pH 6, and studies employing radiolabelled FeCl3 confirmed that FtrABCD transports ferrous iron. Transcription of the ftrA gene is induced in B. abortus 2308 in response to iron deprivation and exposure to acid pH, and similar to other Brucella iron acquisition genes that have been examined the iron-responsiveness of ftrA is dependent upon the iron response regulator Irr. The B. abortus ftrA mutant exhibits significant attenuation in both cultured murine macrophages and experimentally infected mice, supporting the proposition that ferrous iron is a critical iron source for these bacteria in the mammalian host.

  2. Sources, transport and deposition of iron in the global atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, R.; Balkanski, Y.; Boucher, O.; Bopp, L.; Chappell, A.; Ciais, P.; Hauglustaine, D.; Peñuelas, J.; Tao, S.

    2015-06-01

    Atmospheric deposition of iron (Fe) plays an important role in controlling oceanic primary productivity. However, the sources of Fe in the atmosphere are not well understood. In particular, the combustion sources of Fe and the subsequent deposition to the oceans have been accounted for in only few ocean biogeochemical models of the carbon cycle. Here we used a mass-balance method to estimate the emissions of Fe from the combustion of fossil fuels and biomass by accounting for the Fe contents in fuel and the partitioning of Fe during combustion. The emissions of Fe attached to aerosols from combustion sources were estimated by particle size, and their uncertainties were quantified by a Monte Carlo simulation. The emissions of Fe from mineral sources were estimated using the latest soil mineralogical database to date. As a result, the total Fe emissions from combustion averaged for 1960-2007 were estimated to be 5.3 Tg yr-1 (90% confidence of 2.3 to 12.1). Of these emissions, 1, 27 and 72% were emitted in particles < 1 μm (PM1), 1-10 μm (PM1-10), and > 10 μm (PM> 10), respectively, compared to a total Fe emission from mineral dust of 41.0 Tg yr-1 in a log-normal distribution with a mass median diameter of 2.5 μm and a geometric standard deviation of 2. For combustion sources, different temporal trends were found in fine and medium-to-coarse particles, with a notable increase in Fe emissions in PM1 since 2000 due to an increase in Fe emission from motor vehicles (from 0.008 to 0.0103 Tg yr-1 in 2000 and 2007, respectively). These emissions have been introduced in a global 3-D transport model run at a spatial resolution of 0.94° latitude by 1.28° longitude to evaluate our estimation of Fe emissions. The modelled Fe concentrations as monthly means were compared with the monthly (57 sites) or daily (768 sites) measured concentrations at a total of 825 sampling stations. The deviation between modelled and observed Fe concentrations attached to aerosols at the

  3. Sources, transport and deposition of iron in the global atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, R.; Balkanski, Y.; Boucher, O.; Bopp, L.; Chappell, A.; Ciais, P.; Hauglustaine, D.; Peñuelas, J.; Tao, S.

    2015-03-01

    Atmospheric deposition of iron (Fe) plays an important role in controlling oceanic primary productivity. However, the sources of Fe in the atmosphere are not well understood. In particular, the combustion sources of Fe and their deposition over oceans are not accounted for in current biogeochemical models of the carbon cycle. Here we used a mass-balance method to estimate the emissions of Fe from the combustion of fossil fuels and biomass by accounting for the Fe contents in fuel and the partitioning of Fe during combustion. The emissions of Fe attached to aerosols from combustion sources were estimated by particle size, and their uncertainties were quantified by a Monte Carlo simulation. The emissions of Fe from mineral sources were estimated using the latest soil mineralogical database to date. As a result, the total Fe emissions from combustion averaged for 1960-2007 were estimated to be 5.1 Tg yr-1 (90% confidence of 2.2 to 11.5). Of these emissions, 2, 33 and 65% were emitted in particles <1 μm (PM1), 1-10 μm (PM1-10), and >10 μm (PM>10), respectively, compared to total Fe emissions from mineral sources of 41.0 Tg yr-1. For combustion sources, different temporal trends were found in fine and medium-to-coarse particles, with a notable increase in Fe emissions in PM1 and PM1-10 since 2000 due to a rapid increase from motor vehicles. These emissions have been introduced in a global 3-D transport model run at a spatial resolution of of 0.94° latitude by 1.28° longitude to evaluate our estimation of Fe emissions. The modelled Fe concentrations were compared to measurements at 825 sampling stations. The deviation between modelled and observed Fe concentrations attached to aerosols at the surface was within a factor of two at most sampling stations, and the deviation was within a factor of 1.5 at sampling stations dominated by combustion sources. We analyzed the relative contribution of combustion sources to total Fe concentrations over different regions of the

  4. Ndfip2 is a potential regulator of the iron transporter DMT1 in the liver

    PubMed Central

    Foot, Natalie J.; Gembus, Kelly M.; Mackenzie, Kimberly; Kumar, Sharad

    2016-01-01

    The regulation of divalent metal ion transporter DMT1, the primary non-heme iron importer in mammals, is critical for maintaining iron homeostasis. Previously we identified ubiquitin-dependent regulation of DMT1 involving the Nedd4 family of ubiquitin ligases and the Ndfip1 and Ndfip2 adaptors. We also established the in vivo function of Ndfip1 in the regulation of DMT1 in the duodenum of mice. Here we have studied the function of Ndfip2 using Ndfip2-deficient mice. The DMT1 protein levels in the duodenum were comparable in wild type and Ndfip2−/− mice, as was the transport activity of isolated enterocytes. A complete blood examination showed no significant differences between wild type and Ndfip2−/− mice in any of the hematological parameters measured. However, when fed a low iron diet, female Ndfip2−/− mice showed a decrease in liver iron content, although they maintained normal serum iron levels and transferrin saturation, compared to wild type female mice that showed a reduction in serum iron and transferrin saturation. Ndfip2−/− female mice also showed an increase in DMT1 expression in the liver, with no change in male mice. We suggest that Ndfip2 controls DMT1 in the liver with female mice showing a greater response to altered dietary iron than the male mice. PMID:27048792

  5. Iron transport by proteoliposomes containing mitochondrial F(1)F(0) ATP synthase isolated from rat heart.

    PubMed

    Kim, Misun; Song, Eunsook

    2010-04-01

    In this work, we present evidence of Fe(2+) transport by rat heart mitochondrial F(1)F(0) ATP synthase. Iron uptake by the vesicles containing the enzyme was concentration- and temperature-dependent, with an optimum temperature of 37 degrees C. Both ATP and ADP stimulated iron uptake in a concentration-dependent manner, whereas AMP, AMPPCP, and mADP did not. Inhibitors of the enzyme, oligomycin, and resveratrol similarly blocked iron transport. The iron uptake was confirmed by inhibition using specific antibodies against the alpha, beta, and c subunits of the enzyme. Interestingly, slight transport of common divalent and trivalent metal ions such as Mg(+2), Ca(+2), Mn(+2), Zn(+2), Cu(+2), Fe(+3), and Al(+3) was observed. Moreover, Cu(+2), even in the nM range, inhibited iron uptake and attained maximum inhibition of approximately 56%. Inorganic phosphate (Pi) in the medium exerted an opposite effect depending on the type of adenosine nucleotide, which was suppressed with ATP, but enhanced with ADP. A similarly stimulating effect of ATP and ADP with an inverse effect of Pi suggests that the activity of ATPase and ATP synthase may be associated with iron uptake in a different manner, probably via antiport of H(+). PMID:20100539

  6. Biological Electron Transport Systems

    PubMed Central

    Cowan, Dwaine O.; Pasternak, Gavril; Kaufman, Frank

    1970-01-01

    The solid-state electrical conductivities of a number of ferredoxin model compounds are reported. For one of these compounds, (KFeS2)n, an electron transfer rate for a 25 Å unit is shown to be at least 1 × 108 electrons sec-1. The rate becomes proportionally larger for smaller molecular units. This rapid rate is consistant with a short pipe model for electron transport between two reaction sites. Some of the factors leading to this rapid transfer rate are considered. PMID:5269247

  7. Genetic and Functional Analyses of the Actinobacillus actinomycetemcomitans AfeABCD Siderophore-Independent Iron Acquisition System

    PubMed Central

    Rhodes, Eric R.; Tomaras, Andrew P.; McGillivary, Glen; Connerly, Pamela L.; Actis, Luis A.

    2005-01-01

    The Actinobacillus actinomycetemcomitans afeABCD iron transport system, the expression of which is controlled by iron and Fur, was identified in three different isolates. The protein products of this locus are related to bacterial ABC transporters involved in metal transport. Transformation of the Escherichia coli 1017 iron acquisition mutant with a plasmid harboring afeABCD promoted cell growth under iron-chelated conditions. However, insertion disruption of each of the afeABCD coding regions abolished this growth-relieving effect. The replacement of the parental afeA allele with the derivative afeA::EZ::TN drastically reduced the ability of A. actinomycetemcomitans cells to grow under iron-chelated conditions. PMID:15908408

  8. The FupA/B protein uniquely facilitates transport of ferrous iron and siderophore-associated ferric iron across the outer membrane of Francisella tularensis live vaccine strain.

    PubMed

    Ramakrishnan, Girija; Sen, Bhaswati

    2014-02-01

    Francisella tularensis is a highly infectious Gram-negative pathogen that replicates intracellularly within the mammalian host. One of the factors associated with virulence of F. tularensis is the protein FupA that mediates high-affinity transport of ferrous iron across the outer membrane. Together with its paralogue FslE, a siderophore-ferric iron transporter, FupA supports survival of the pathogen in the host by providing access to the essential nutrient iron. The FupA orthologue in the attenuated live vaccine strain (LVS) is encoded by the hybrid gene fupA/B, the product of an intergenic recombination event that significantly contributes to attenuation of the strain. We used (55)Fe transport assays with mutant strains complemented with the different paralogues to show that the FupA/B protein of LVS retains the capacity for high-affinity transport of ferrous iron, albeit less efficiently than FupA of virulent strain Schu S4. (55)Fe transport assays using purified siderophore and siderophore-dependent growth assays on iron-limiting agar confirmed previous findings that FupA/B also contributes to siderophore-mediated ferric iron uptake. These assays further demonstrated that the LVS FslE protein is a weaker siderophore-ferric iron transporter than the orthologue from Schu S4, and may be a result of the sequence variation between the two proteins. Our results indicate that iron-uptake mechanisms in LVS differ from those in Schu S4 and that functional differences in the outer membrane iron transporters have distinct effects on growth under iron limitation.

  9. Transport characteristics of surface-modified nanoscale zero-valent iron in porous media.

    PubMed

    Kanel, S R; Choi, H

    2007-01-01

    Highly efficient, versatile, adsorbent, nanoscale zero-valent iron (NZVI) was synthesised and encapsulated by an anionic polymer to make it a mobile delivery vehicle (DV-NZVI) for in-situ groundwater and soil remediation. NZVI was found to be highly dispersed with surfactant within a size of 1-100 nm. Laboratory column experiments were conducted by employing glass beads as a porous medium to delineate the characteristics of DV-NZVI transport as a reactive material in saturated zones under a number of conditions. It was observed that there was an optimum concentration of polymer, i.e. 6 g/L, for maximum transport of DV-NZVI, at which point, as the flow rate increases, the transport of DV-NZVI increases. Similarly, at the optimum concentration we observed that as the depth of porous media increased, the breakthrough of DV-NZVI was retarded. These results confirmed that DV-NZVI has significant potential for use as a colloidal reactive barrier material in deep groundwater systems in lieu of pump and treat approaches and conventional permeable reactive barriers (PRB).

  10. Heat transport system

    DOEpatents

    Harkness, Samuel D.

    1982-01-01

    A falling bed of ceramic particles receives neutron irradiation from a neutron-producing plasma and thereby transports energy as heat from the plasma to a heat exchange location where the ceramic particles are cooled by a gas flow. The cooled ceramic particles are elevated to a location from which they may again pass by gravity through the region where they are exposed to neutron radiation. Ceramic particles of alumina, magnesia, silica and combinations of these materials are contemplated as high-temperature materials that will accept energy from neutron irradiation. Separate containers of material incorporating lithium are exposed to the neutron flux for the breeding of tritium that may subsequently be used in neutron-producing reactions. The falling bed of ceramic particles includes velocity partitioning between compartments near to the neutron-producing plasma and compartments away from the plasma to moderate the maximum temperature in the bed.

  11. Heat transport system

    DOEpatents

    Harkness, S.D.

    A falling bed of ceramic particles receives neutron irradiation from a neutron-producing plasma and thereby transports energy as heat from the plasma to a heat exchange location where the ceramic particles are cooled by a gas flow. The cooled ceramic particles are elevated to a location from which they may again pass by gravity through the region where they are exposed to neutron radiation. Ceramic particles of alumina, magnesia, silica and combinations of these materials are contemplated as high-temperature materials that will accept energy from neutron irradiation. Separate containers of material incorporating lithium are exposed to the neutron flux for the breeding of tritium that may subsequently be used in neutron-producing reactions. The falling bed of ceramic particles includes velocity partitioning between compartments near to the neutron-producing plasma and compartments away from the plasma to moderate the maximum temperature in the bed.

  12. Understanding and Controlling iron Release in Distribution Systems

    EPA Science Inventory

    Generation of red-water resulting from the release of iron from drinking water distribution system materials is a major consumer complaint of drinking water systems. The objective of this presentation is to provide a fundamental basis for iron release from drinking water distrib...

  13. Advanced Transport Operating Systems Program

    NASA Technical Reports Server (NTRS)

    White, John J.

    1990-01-01

    NASA-Langley's Advanced Transport Operating Systems Program employs a heavily instrumented, B 737-100 as its Transport Systems Research Vehicle (TRSV). The TRSV has been used during the demonstration trials of the Time Reference Scanning Beam Microwave Landing System (TRSB MLS), the '4D flight-management' concept, ATC data links, and airborne windshear sensors. The credibility obtainable from successful flight test experiments is often a critical factor in the granting of substantial commitments for commercial implementation by the FAA and industry. In the case of the TRSB MLS, flight test demonstrations were decisive to its selection as the standard landing system by the ICAO.

  14. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  15. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  16. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  17. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  18. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  19. Nitric oxide reduces nontransferrin-bound iron transport in HepG2 cells.

    PubMed

    Barisani, D; Cairo, G; Ginelli, E; Marozzi, A; Conte, D

    1999-02-01

    Nitric oxide (NO) donors S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside (SNP) modulate iron regulatory protein (IRP) activity and may, therefore, affect iron uptake through transferrin receptor expression. However, iron also enters the cell as nontransferrin-bound iron (NTBI), and the aim of this study was to evaluate the effects of NO donors on NTBI transport in HepG2 cells, a model of liver physiology. Incubation with SNP and SNAP led to a time- and concentration-dependent reduction in Fe3+ and Fe2+ uptake, thus indicating an effect on the transporter rather than on the reductase. In terms of Fe2+ uptake, no variations in the Michaelis-Menten constant (Km) and a reduction in maximum uptake (Vmax) (50, 33, and 16.6 fmol/microgram protein/min in control, SNP-, and SNAP-treated cells, respectively) were detected, which suggested a decrease in the number of putative NTBI transport protein(s). Gel shift assays showed that IRP activity was reduced by SNP and slightly increased by SNAP. Northern blot analysis of transferrin receptor messenger RNA (mRNA) levels showed variations similar to those observed for IRPs, but both NO donors increased L-ferritin mRNA levels and had no effect on the stimulator of Fe transport (SFT) mRNA. In conclusion, NO donors significantly reduce NTBI transport in HepG2 cells, an effect that seems to be IRP and SFT independent. Moreover, the reduction in NTBI uptake after NO treatment suggests that this form of iron may play a minor role in the increased hepatic iron stores observed in inflammation or that other liver cells are more involved in this pathological condition.

  20. Regulation of iron transport related genes by boron in the marine bacterium Marinobacter algicola DG893.

    PubMed

    Romano, Ariel; Trimble, Lyndsay; Hobusch, Ashtian R; Schroeder, Kristine J; Amin, Shady A; Hartnett, Andrej D; Barker, Ryan A; Crumbliss, Alvin L; Carrano, Carl J

    2013-08-01

    While there has been extensive interest in the use of boron isotope ratios as a surrogate of pH in paleoclimate studies in the context of climate change-related questions, the high (0.4 mM) concentration and the depth-independent (conservative or non-nutrient-like) concentration profile of this element have led to boron being neglected as a potentially biologically relevant element in the modern ocean. Here we report that boron affects the expression of a number of protein and genes in the "algal-associated" Gram-negative marine bacterium Marinobacter algicola DG893. Most intriguingly, a number of these proteins and genes are related to iron uptake. In a recent separate publication we have shown that boron regulates one such iron transport related protein, i.e. the periplasmic iron binding protein FbpA via a direct interaction of the metalloid with this protein. Here we show that a number of other iron uptake related genes are also affected by boron but in the opposite way i.e. they are up-regulated. We propose that the differential effect of boron on FbpA expression relative to other iron transport related genes is a result of an interaction between boron and the global iron regulatory protein Fur.

  1. A Trypanosomatid Iron Transporter that Regulates Mitochondrial Function Is Required for Leishmania amazonensis Virulence

    PubMed Central

    Mittra, Bidyottam; Laranjeira-Silva, Maria Fernanda; Perrone Bezerra de Menezes, Juliana; Jensen, Jennifer; Michailowsky, Vladimir; Andrews, Norma W.

    2016-01-01

    Iron, an essential co-factor of respiratory chain proteins, is critical for mitochondrial function and maintenance of its redox balance. We previously reported a role for iron uptake in differentiation of Leishmania amazonensis into virulent amastigotes, by a mechanism that involves reactive oxygen species (ROS) production and is independent of the classical pH and temperature cues. Iron import into mitochondria was proposed to be essential for this process, but evidence supporting this hypothesis was lacking because the Leishmania mitochondrial iron transporter was unknown. Here we describe MIT1, a homolog of the mitochondrial iron importer genes mrs3 (yeast) and mitoferrin-1 (human) that is highly conserved among trypanosomatids. MIT1 expression was essential for the survival of Trypanosoma brucei procyclic but not bloodstream forms, which lack functional respiratory complexes. L. amazonensis LMIT1 null mutants could not be generated, suggesting that this mitochondrial iron importer is essential for promastigote viability. Promastigotes lacking one LMIT1 allele (LMIT1/Δlmit1) showed growth defects and were more susceptible to ROS toxicity, consistent with the role of iron as the essential co-factor of trypanosomatid mitochondrial superoxide dismutases. LMIT1/Δlmit1 metacyclic promastigotes were unable to replicate as intracellular amastigotes after infecting macrophages or cause cutaneous lesions in mice. When induced to differentiate axenically into amastigotes, LMIT1/Δlmit1 showed strong defects in iron content and function of mitochondria, were unable to upregulate the ROS-regulatory enzyme FeSOD, and showed mitochondrial changes suggestive of redox imbalance. Our results demonstrate the importance of mitochondrial iron uptake in trypanosomatid parasites, and highlight the role of LMIT1 in the iron-regulated process that orchestrates differentiation of L. amazonensis into infective amastigotes. PMID:26741360

  2. A Trypanosomatid Iron Transporter that Regulates Mitochondrial Function Is Required for Leishmania amazonensis Virulence.

    PubMed

    Mittra, Bidyottam; Laranjeira-Silva, Maria Fernanda; Perrone Bezerra de Menezes, Juliana; Jensen, Jennifer; Michailowsky, Vladimir; Andrews, Norma W

    2016-01-01

    Iron, an essential co-factor of respiratory chain proteins, is critical for mitochondrial function and maintenance of its redox balance. We previously reported a role for iron uptake in differentiation of Leishmania amazonensis into virulent amastigotes, by a mechanism that involves reactive oxygen species (ROS) production and is independent of the classical pH and temperature cues. Iron import into mitochondria was proposed to be essential for this process, but evidence supporting this hypothesis was lacking because the Leishmania mitochondrial iron transporter was unknown. Here we describe MIT1, a homolog of the mitochondrial iron importer genes mrs3 (yeast) and mitoferrin-1 (human) that is highly conserved among trypanosomatids. MIT1 expression was essential for the survival of Trypanosoma brucei procyclic but not bloodstream forms, which lack functional respiratory complexes. L. amazonensis LMIT1 null mutants could not be generated, suggesting that this mitochondrial iron importer is essential for promastigote viability. Promastigotes lacking one LMIT1 allele (LMIT1/Δlmit1) showed growth defects and were more susceptible to ROS toxicity, consistent with the role of iron as the essential co-factor of trypanosomatid mitochondrial superoxide dismutases. LMIT1/Δlmit1 metacyclic promastigotes were unable to replicate as intracellular amastigotes after infecting macrophages or cause cutaneous lesions in mice. When induced to differentiate axenically into amastigotes, LMIT1/Δlmit1 showed strong defects in iron content and function of mitochondria, were unable to upregulate the ROS-regulatory enzyme FeSOD, and showed mitochondrial changes suggestive of redox imbalance. Our results demonstrate the importance of mitochondrial iron uptake in trypanosomatid parasites, and highlight the role of LMIT1 in the iron-regulated process that orchestrates differentiation of L. amazonensis into infective amastigotes. PMID:26741360

  3. A Trypanosomatid Iron Transporter that Regulates Mitochondrial Function Is Required for Leishmania amazonensis Virulence.

    PubMed

    Mittra, Bidyottam; Laranjeira-Silva, Maria Fernanda; Perrone Bezerra de Menezes, Juliana; Jensen, Jennifer; Michailowsky, Vladimir; Andrews, Norma W

    2016-01-01

    Iron, an essential co-factor of respiratory chain proteins, is critical for mitochondrial function and maintenance of its redox balance. We previously reported a role for iron uptake in differentiation of Leishmania amazonensis into virulent amastigotes, by a mechanism that involves reactive oxygen species (ROS) production and is independent of the classical pH and temperature cues. Iron import into mitochondria was proposed to be essential for this process, but evidence supporting this hypothesis was lacking because the Leishmania mitochondrial iron transporter was unknown. Here we describe MIT1, a homolog of the mitochondrial iron importer genes mrs3 (yeast) and mitoferrin-1 (human) that is highly conserved among trypanosomatids. MIT1 expression was essential for the survival of Trypanosoma brucei procyclic but not bloodstream forms, which lack functional respiratory complexes. L. amazonensis LMIT1 null mutants could not be generated, suggesting that this mitochondrial iron importer is essential for promastigote viability. Promastigotes lacking one LMIT1 allele (LMIT1/Δlmit1) showed growth defects and were more susceptible to ROS toxicity, consistent with the role of iron as the essential co-factor of trypanosomatid mitochondrial superoxide dismutases. LMIT1/Δlmit1 metacyclic promastigotes were unable to replicate as intracellular amastigotes after infecting macrophages or cause cutaneous lesions in mice. When induced to differentiate axenically into amastigotes, LMIT1/Δlmit1 showed strong defects in iron content and function of mitochondria, were unable to upregulate the ROS-regulatory enzyme FeSOD, and showed mitochondrial changes suggestive of redox imbalance. Our results demonstrate the importance of mitochondrial iron uptake in trypanosomatid parasites, and highlight the role of LMIT1 in the iron-regulated process that orchestrates differentiation of L. amazonensis into infective amastigotes.

  4. Tether Transportation System Study

    NASA Technical Reports Server (NTRS)

    Bangham, M. E.; Lorenzini, E.; Vestal, L.

    1998-01-01

    The projected traffic to geostationary earth orbit (GEO) is expected to increase over the next few decades. At the same time, the cost of delivering payloads from the Earth's surface to low earth orbit (LEO) is projected to decrease, thanks in part to the Reusable Launch Vehicle (RLV). A comparable reduction in the cost of delivering payloads from LEO to GEO is sought. The use of in-space tethers, eliminating the requirement for traditional chemical upper stages and thereby reducing the launch mass, has been identified as such an alternative. Spinning tethers are excellent kinetic energy storage devices for providing the large delta vee's required for LEO to GEO transfer. A single-stage system for transferring payloads from LEO to GEO was proposed some years ago. The study results presented here contain the first detailed analyses of this proposal, its extension to a two-stage system, and the likely implementation of the operational system.

  5. Iron-titanium oxyhydroxides which transport water into the deep upper mantle and mantle transition zone

    NASA Astrophysics Data System (ADS)

    Matsukage, K. N.; Nishihara, Y.

    2015-12-01

    We experimentally discovered a new hydrous phase in the system FeOOH-TiO2 at pressures of 10-16 GPa and temperatures of 1000-1600°C which corresponds to conditions of the deep upper mantle and the Earth's mantle transition zone. Seven different compositions in the FeOOH-TiO2 system having molar ratios of x = Ti/(Fe + Ti) = 0, 0.125, 0.25, 0.375, 0.5, 0.75 that were prepared by mixing reagent grade a-FeOOH (goethite) and TiO2 (anatase) powders were used as starting materials. High-pressure and high-temperature experiments were carried out using Kawai-type multi-anvil apparatus (Orange-1000 at Ehime University and SPI-1000 at Tokyo Institute of Technology). In this system, we identified two stable iron-titanium oxyhydroxide phases whose estimated composition is expressed by (FeH)1 - xTixO2 . One is the Fe-rich solid solution (x < 0.23) with e-FeOOH type crystal structure (e-phase, orthorhombic, P21nm) that was described by the previous studies (e.g., Suzuki 2010), and the other is the more Ti-rich solid solution (x > 0.35) with a-PbO2 type structure (a-phase, orthorhombic, Pbcn). The a-phase is stable up to 1500ºC for a composition of x = 0.5 and at least to 1600ºC for x = 0.75. Our result means that this phase is stable at average mantle temperature in the Earth's mantle transition zone. The Iron-titanium-rich hydrous phases was possible to stable in basalt + H2O system (e.g., Hashimoto and Matsukage 2013). Therefore our findings suggest that water transport in the Earth's deep interior is probably much more efficient than had been previously thought.

  6. Effects of aspirin on expression of iron transport and storage proteins in BV-2 microglial cells.

    PubMed

    Xu, Yan Xin; Du, Fang; Jiang, Li Rong; Gong, Jing; Zhou, Yu-Fu; Luo, Qian Qian; Qian, Zhong Ming; Ke, Ya

    2015-12-01

    In the light of recent studies, we hypothesized that aspirin might have the functions to regulate the expression of iron transport proteins and then affect cellular iron levels. To test this hypothesis, we investigated the effects of aspirin on expression of iron uptake protein transferrin receptor 1 (TfR1), iron release protein ferroportin 1 (Fpn1) and iron storage protein ferritin using Western blot analysis and on tumor necrosis factor (TNF)-αlpha, interleukin (IL)-6, interleukin (IL)-10 and hepcidin using quantitative real-time PCR in BV-2 microglial cells treated with lipopolysaccharides (LPS). We found that aspirin significantly down-regulated TfR1, while also up-regulated Fpn1 and ferritin expressions in BV-2 microglial cells in vitro. We also showed that TfR1 and Fpn1 expressions were significantly higher, while ferritin contents, IL-6, TNF-alpha and hepcidin mRNA levels were lower in cells treated with aspirin plus LPS than those in cells treated with LPS only. We concluded that aspirin has a negative effect on cell iron contents under 'normal' conditions and could partly reverse LPS-induced-disruption in cell iron balance under in vitro inflammatory conditions. Our findings also suggested that hepcidin might play a dominant role in the control of TfR1 expression by aspirin in the cells treated with LPS. PMID:26522688

  7. Effects of aspirin on expression of iron transport and storage proteins in BV-2 microglial cells.

    PubMed

    Xu, Yan Xin; Du, Fang; Jiang, Li Rong; Gong, Jing; Zhou, Yu-Fu; Luo, Qian Qian; Qian, Zhong Ming; Ke, Ya

    2015-12-01

    In the light of recent studies, we hypothesized that aspirin might have the functions to regulate the expression of iron transport proteins and then affect cellular iron levels. To test this hypothesis, we investigated the effects of aspirin on expression of iron uptake protein transferrin receptor 1 (TfR1), iron release protein ferroportin 1 (Fpn1) and iron storage protein ferritin using Western blot analysis and on tumor necrosis factor (TNF)-αlpha, interleukin (IL)-6, interleukin (IL)-10 and hepcidin using quantitative real-time PCR in BV-2 microglial cells treated with lipopolysaccharides (LPS). We found that aspirin significantly down-regulated TfR1, while also up-regulated Fpn1 and ferritin expressions in BV-2 microglial cells in vitro. We also showed that TfR1 and Fpn1 expressions were significantly higher, while ferritin contents, IL-6, TNF-alpha and hepcidin mRNA levels were lower in cells treated with aspirin plus LPS than those in cells treated with LPS only. We concluded that aspirin has a negative effect on cell iron contents under 'normal' conditions and could partly reverse LPS-induced-disruption in cell iron balance under in vitro inflammatory conditions. Our findings also suggested that hepcidin might play a dominant role in the control of TfR1 expression by aspirin in the cells treated with LPS.

  8. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  9. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  10. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  11. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  12. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  13. Higher concentrations of nanoscale zero-valent iron (nZVI) in soil induced rice chlorosis due to inhibited active iron transportation.

    PubMed

    Wang, Jie; Fang, Zhanqiang; Cheng, Wen; Yan, Xiaomin; Tsang, Pokeung Eric; Zhao, Dongye

    2016-03-01

    In this study, the effects of concentrations 0, 100, 250, 500, 750 and 1000 mg kg(-1) of nanoscale zero-valent iron (nZVI) on germination, seedlings growth, physiology and toxicity mechanisms were investigated. The results showed that nZVI had no effect on germination, but inhibited the rice seedlings growth in higher concentrations (>500 mg kg(-1) nZVI). The highest suppression rate of the length of roots and shoots reached 46.9% and 57.5%, respectively. The 1000mg kg(-1) nZVI caused the highest suppression rates for chlorophyll and carotenoids, at 91.6% and 85.2%, respectively. In addition, the activity of antioxidant enzymes was altered by the translocation of nanoparticles and changes in active iron content. Visible symptoms of iron deficiency were observed at higher concentrations, at which the active iron content decreased 61.02% in the shoots, but the active iron content not decreased in roots. Interestingly, the total and available amounts of iron in the soil were not less than those in the control. Therefore, the plants iron deficiency was not caused by (i) deficiency of available iron in the soil and (ii) restraint of the absorption that plant takes in the available iron, while induced by (ⅲ) the transport of active iron from the root to the shoot was blocked. The cortex tissues were seriously damaged by nZVI which was transported from soil to the root, these were proved by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). This current study shows that the mechanism of iron deficiency in rice seedling was due to transport of active iron from the root to the shoot blocked, which was caused by the uptake of nZVI.

  14. Higher concentrations of nanoscale zero-valent iron (nZVI) in soil induced rice chlorosis due to inhibited active iron transportation.

    PubMed

    Wang, Jie; Fang, Zhanqiang; Cheng, Wen; Yan, Xiaomin; Tsang, Pokeung Eric; Zhao, Dongye

    2016-03-01

    In this study, the effects of concentrations 0, 100, 250, 500, 750 and 1000 mg kg(-1) of nanoscale zero-valent iron (nZVI) on germination, seedlings growth, physiology and toxicity mechanisms were investigated. The results showed that nZVI had no effect on germination, but inhibited the rice seedlings growth in higher concentrations (>500 mg kg(-1) nZVI). The highest suppression rate of the length of roots and shoots reached 46.9% and 57.5%, respectively. The 1000mg kg(-1) nZVI caused the highest suppression rates for chlorophyll and carotenoids, at 91.6% and 85.2%, respectively. In addition, the activity of antioxidant enzymes was altered by the translocation of nanoparticles and changes in active iron content. Visible symptoms of iron deficiency were observed at higher concentrations, at which the active iron content decreased 61.02% in the shoots, but the active iron content not decreased in roots. Interestingly, the total and available amounts of iron in the soil were not less than those in the control. Therefore, the plants iron deficiency was not caused by (i) deficiency of available iron in the soil and (ii) restraint of the absorption that plant takes in the available iron, while induced by (ⅲ) the transport of active iron from the root to the shoot was blocked. The cortex tissues were seriously damaged by nZVI which was transported from soil to the root, these were proved by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). This current study shows that the mechanism of iron deficiency in rice seedling was due to transport of active iron from the root to the shoot blocked, which was caused by the uptake of nZVI. PMID:26803790

  15. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  16. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  17. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  18. Atmospheric transport of iron and its deposition in the ocean

    SciTech Connect

    Duce, R.A.; Tindale, N.W. )

    1991-12-01

    The atmospheric transport of continental weathering products is responsible for much of the mineral material and Fe entering the open ocean and is probably the dominant source of nutrient Fe in the photic zone. In regions where other nutrients are present in high concentrations, the flux of Fe from the atmosphere may be a limiting factor in primary productivity. Due to the larger source regions for dust north of the equator, {approximately}8 times more atmospheric Fe is deposited in the northern hemisphere than in the southern hemisphere. The mineral aerosol and Fe transport and deposition are highly variable due to the episodic nature of dust generation and its transport and deposition processes. Between 10 and 50% of the total atmospheric Fe entering the world ocean appears to dissolve rapidly when the mineral matter enters the ocean. Much of the atmospheric Fe is present as Fe(II), apparently produced as a result of photochemical reduction reactions taking place during atmospheric transport. This readily soluble Fe(II) should be available immediately for use as a nutrient by phytoplankton. Atmospheric transport from the continents is estimated to supply {approximately}3 times as much dissolved Fe to the oceans as that delivered via rivers.

  19. Transport Systems in Halophilic Fungi.

    PubMed

    Plemenitaš, Ana; Konte, Tilen; Gostinčar, Cene; Cimerman, Nina Gunde

    2016-01-01

    Fungi that tolerate very high environmental NaCl concentrations are good model systems to study mechanisms that enable them to endure osmotic and salinity stress. The whole genome sequences of six such fungal species have been analysed: Hortaea werneckii, Wallemia ichthyophaga and four Aureobasidium spp.: A. pullulans, A. subglaciale, A. melanogenum and A. namibiae. These fungi show different levels of halotolerance, with the presence of numerous membrane transport systems uncovered here that are believed to maintain physiological intracellular concentrations of alkali metal cations. Despite some differences, the intracellular cation contents of H. werneckii, A. pullulans and W. ichthyophaga remain low even under extreme extracellular salinities, which suggests that these species have efficient cation transport systems. We speculate that cation transporters prevent intracellular accumulation of Na(+), and thus avoid the toxic effects that such Na(+) accumulation would have, while also maintaining the high K(+)/Na(+) ratio that is required for the full functioning of the cell - another crucial task in high-Na(+) environments. This chapter primarily summarises the cation transport systems of these selected fungi, and it also describes other membrane transporters that might be involved in their mechanisms of halotolerance.

  20. Earthquake damage to transportation systems

    USGS Publications Warehouse

    McCullough, Heather

    1994-01-01

    Earthquakes represent one of the most destructive natural hazards known to man. A large magnitude earthquake near a populated area can affect residents over thousands of square kilometers and cause billions of dollars in property damage. Such an event can kill or injure thousands of residents and disrupt the socioeconomic environment for months, sometimes years. A serious result of a large-magnitude earthquake is the disruption of transportation systems, which limits post-disaster emergency response. Movement of emergency vehicles, such as police cars, fire trucks and ambulances, is often severely restricted. Damage to transportation systems is categorized below by cause including: ground failure, faulting, vibration damage, and tsunamis.

  1. System and method for producing metallic iron

    SciTech Connect

    Englund, David J.; Schlichting, Mark; Meehan, John; Crouch, Jeremiah; Wilson, Logan

    2014-07-29

    A method of production of metallic iron nodules comprises assembling a hearth furnace having a moveable hearth comprising refractory material and having a conversion zone and a fusion zone, providing a hearth material layer comprising carbonaceous material on the refractory material, providing a layer of reducible material comprising and iron bearing material arranged in discrete portions over at least a portion of the hearth material layer, delivering oxygen gas into the hearth furnace to a ratio of at least 0.8:1 ponds of oxygen to pounds of iron in the reducible material to heat the conversion zone to a temperature sufficient to at least partially reduce the reducible material and to heat the fusion zone to a temperature sufficient to at least partially reduce the reducible material, and heating the reducible material to form one or more metallic iron nodules and slag.

  2. Surveillance systems for intermodal transportation

    NASA Astrophysics Data System (ADS)

    Jakovlev, Sergej; Voznak, Miroslav; Andziulis, Arunas

    2015-05-01

    Intermodal container monitoring is considered a major security issue in many major logistic companies and countries worldwide. Current representation of the problem, we face today, originated in 2002, right after the 9/11 attacks. Then, a new worldwide Container Security Initiative (CSI, 2002) was considered that shaped the perception of the transportation operations. Now more than 80 larger ports all over the world contribute to its further development and integration into everyday transportation operations and improve the regulations for the developing regions. Although, these new improvements allow us to feel safer and secure, constant management of transportation operations has become a very difficult problem for conventional data analysis methods and information systems. The paper deals with a proposal of a whole new concept for the improvement of the Containers Security Initiative (CSI) by virtually connecting safety, security processes and systems. A conceptual middleware approach with deployable intelligent agent modules is proposed to be used with possible scenarios and a testbed is used to test the solution. Middleware examples are visually programmed using National Instruments LabView software packages and Wireless sensor network hardware modules. An experimental software is used to evaluate he solution. This research is a contribution to the intermodal transportation and is intended to be used as a means or the development of intelligent transport systems.

  3. Uptake and transport of superparamagnetic iron oxide nanoparticles through human brain capillary endothelial cells.

    PubMed

    Thomsen, L B; Linemann, T; Pondman, K M; Lichota, J; Kim, K S; Pieters, R J; Visser, G M; Moos, T

    2013-10-16

    The blood-brain barrier (BBB) formed by brain capillary endothelial cells (BCECs) constitutes a firm physical, chemical, and immunological barrier, making the brain accessible to only a few percent of potential drugs intended for treatment inside the central nervous system. With the purpose of overcoming the restraints of the BBB by allowing the transport of drugs, siRNA, or DNA into the brain, a novel approach is to use superparamagnetic iron oxide nanoparticles (SPIONs) as drug carriers. The aim of this study was to investigate the ability of fluorescent SPIONs to pass through human brain microvascular endothelial cells facilitated by an external magnet. The ability of SPIONs to penetrate the barrier was shown to be significantly stronger in the presence of an external magnetic force in an in vitro BBB model. Hence, particles added to the luminal side of the in vitro BBB model were found in astrocytes cocultured at a remote distance on the abluminal side, indicating that particles were transported through the barrier and taken up by astrocytes. Addition of the SPIONs to the culture medium did not negatively affect the viability of the endothelial cells. The magnetic force-mediated dragging of SPIONs through BCECs may denote a novel mechanism for the delivery of drugs to the brain.

  4. System and method for producing metallic iron nodules

    DOEpatents

    Bleifuss, Rodney L.; Englund, David J.; Iwasaki, Iwao; Lindgren, Andrew J.; Kiesel, Richard F.

    2011-09-20

    A method for producing metallic iron nodules by assembling a shielding entry system to introduce coarse carbonaceous material greater than 6 mesh in to the furnace atmosphere at location(s) where the temperature of the furnace atmosphere adjacent at least partially reduced reducible iron bearing material is between about 2200 and 2650.degree. F. (1200 and 1450.degree. C.), the shielding entry system adapted to inhibit emission of infrared radiation from the furnace atmosphere and seal the furnace atmosphere from exterior atmosphere while introducing coarse carbonaceous material greater than 6 mesh into the furnace to be distributed over the at least partially reduced reducible iron bearing material, and heating the covered at least partially reduced reducible iron bearing material in a fusion atmosphere to assist in fusion and inhibit reoxidation of the reduced material during fusion to assist in fusion and inhibit reoxidation of the reduced material in forming metallic iron nodules.

  5. Alaska Natural Gas Transportation System

    SciTech Connect

    Jones, V.T.

    1984-04-27

    The proven reserves of natural gas in Prudhoe Bay remain the single largest block of reserves under US control. The sponsors of the Alaska Natural Gas Transportation System, including The Williams Companies, remain convinced that Alaskan gas will be increasingly important to meet future needs here in the lower 48 states. Both Canada and the US will increasingly have to turn to more costly supplies of gas as the closer, traditional areas of gas supply are exhausted. A principal motivation for Canada's participation in the ANGTS was the prospect of a jointly sponsored pipeline through Canada which would facilitate bringing frontier gas to market - through the so-called Dempster lateral. The high cost of transportation systems in the Artic necessitates pipelines with large capacities in order to minimize the cost of transportation per unit of gas delivered. It is clear that Canada still strongly supports the ANGTS project as a means of opening up the frontier resources of both Alaska and Canada.

  6. Diagnosis of energy transport in iron buried layer targets using an extreme ultraviolet laser

    SciTech Connect

    Shahzad, M.; Culfa, O.; Rossall, A. K.; Tallents, G. J.; Wilson, L. A.; Guilbaud, O.; Kazamias, S.; Delmas, O.; Demailly, J.; Maitrallain, A.; Pittman, M.; Baynard, E.; Farjardo, M.

    2015-02-15

    We demonstrate the use of extreme ultra-violet (EUV) laboratory lasers in probing energy transport in laser irradiated solid targets. EUV transmission through targets containing a thin layer of iron (50 nm) encased in plastic (CH) after irradiation by a short pulse (35 fs) laser focussed to irradiances 3 × 10{sup 16} Wcm{sup −2} is measured. Heating of the iron layer gives rise to a rapid decrease in EUV opacity and an increase in the transmission of the 13.9 nm laser radiation as the iron ionizes to Fe{sup 5+} and above where the ion ionisation energy is greater than the EUV probe photon energy (89 eV). A one dimensional hydrodynamic fluid code HYADES has been used to simulate the temporal variation in EUV transmission (wavelength 13.9 nm) using IMP opacity values for the iron layer and the simulated transmissions are compared to measured transmission values. When a deliberate pre-pulse is used to preform an expanding plastic plasma, it is found that radiation is important in the heating of the iron layer while for pre-pulse free irradiation, radiation transport is not significant.

  7. Rice OsYSL15 is an iron-regulated iron(III)-deoxymugineic acid transporter expressed in the roots and is essential for iron uptake in early growth of the seedlings.

    PubMed

    Inoue, Haruhiko; Kobayashi, Takanori; Nozoye, Tomoko; Takahashi, Michiko; Kakei, Yusuke; Suzuki, Kazumasa; Nakazono, Mikio; Nakanishi, Hiromi; Mori, Satoshi; Nishizawa, Naoko K

    2009-02-01

    Graminaceous plants take up iron through YS1 (yellow stripe 1) and YS1-like (YSL) transporters using iron-chelating compounds known as mugineic acid family phytosiderophores. We examined the expression of 18 rice (Oryza sativa L.) YSL genes (OsYSL1-18) in the epidermis/exodermis, cortex, and stele of rice roots. Expression of OsYSL15 in root epidermis and stele was induced by iron deficiency and showed daily fluctuation. OsYSL15 restored a yeast mutant defective in iron uptake when supplied with iron(III)-deoxymugineic acid and transported iron(III)-deoxymugineic acid in Xenopus laevis oocytes. An OsYSL15-green fluorescent protein fusion was localized to the plasma membrane when transiently expressed in onion epidermal cells. OsYSL15 promoter-beta-glucuronidase analysis revealed that OsYSL15 expression in roots was dominant in the epidermis/exodermis and phloem cells under conditions of iron deficiency and was detected only in phloem under iron sufficiency. These results strongly suggest that OsYSL15 is the dominant iron(III)-deoxymugineic acid transporter responsible for iron uptake from the rhizosphere and is also responsible for phloem transport of iron. OsYSL15 was also expressed in flowers, developing seeds, and in the embryonic scutellar epithelial cells during seed germination. OsYSL15 knockdown seedlings showed severe arrest in germination and early growth and were rescued by high iron supply. These results demonstrate that rice OsYSL15 plays a crucial role in iron homeostasis during the early stages of growth. PMID:19049971

  8. A systematic analysis reveals an essential role for high-affinity iron uptake system, haemolysin and CFEM domain-containing protein in iron homoeostasis and virulence in Candida glabrata.

    PubMed

    Srivastava, Vivek Kumar; Suneetha, Korivi Jyothiraj; Kaur, Rupinder

    2014-10-01

    Iron is an essential nutrient for all living organisms and human pathogens employ a battery of factors to scavenge iron from the high-affinity iron-binding host proteins. In the present study, we have elucidated, via a candidate gene approach, major iron acquisition and homoeostatic mechanisms operational in an opportunistic human fungal pathogen Candida glabrata. Phenotypic, biochemical and molecular analysis of a set of 13 C. glabrata strains, deleted for proteins potentially implicated in iron metabolism, revealed that the high-affinity reductive iron uptake system is required for utilization of alternate carbon sources and for growth under both in vitro iron-limiting and in vivo conditions. Furthermore, we show for the first time that the cysteine-rich CFEM (common in fungal extracellular membranes) domain-containing cell wall structural protein, CgCcw14, and a putative haemolysin, CgMam3, are essential for maintenance of intracellular iron content, adherence to epithelial cells and virulence. Consistent with their roles in iron homoeostasis, mitochondrial aconitase activity was lower and higher in mutants disrupted for high-affinity iron transport, and haemolysin respectively. Additionally, we present evidence that the mitochondrial frataxin, CgYfh1, is pivotal to iron metabolism. Besides yielding insights into major in vitro and in vivo iron acquisition strategies, our findings establish high-affinity iron uptake mechanisms as critical virulence determinants in C. glabrata.

  9. Optimal concentrations in transport systems

    PubMed Central

    Jensen, Kaare H.; Kim, Wonjung; Holbrook, N. Michele; Bush, John W. M.

    2013-01-01

    Many biological and man-made systems rely on transport systems for the distribution of material, for example matter and energy. Material transfer in these systems is determined by the flow rate and the concentration of material. While the most concentrated solutions offer the greatest potential in terms of material transfer, impedance typically increases with concentration, thus making them the most difficult to transport. We develop a general framework for describing systems for which impedance increases with concentration, and consider material flow in four different natural systems: blood flow in vertebrates, sugar transport in vascular plants and two modes of nectar drinking in birds and insects. The model provides a simple method for determining the optimum concentration copt in these systems. The model further suggests that the impedance at the optimum concentration μopt may be expressed in terms of the impedance of the pure (c = 0) carrier medium μ0 as μopt∼2αμ0, where the power α is prescribed by the specific flow constraints, for example constant pressure for blood flow (α = 1) or constant work rate for certain nectar-drinking insects (α = 6). Comparing the model predictions with experimental data from more than 100 animal and plant species, we find that the simple model rationalizes the observed concentrations and impedances. The model provides a universal framework for studying flows impeded by concentration, and yields insight into optimization in engineered systems, such as traffic flow. PMID:23594815

  10. Artificial siderophores. 1. Synthesis and microbial iron transport capabilities.

    PubMed

    Lee, B H; Miller, M J; Prody, C A; Neilands, J B

    1985-03-01

    Several di- and trihydroxamate analogues of natural microbial iron chelators have been prepared. The syntheses involved linkage of core structural units, including pyridinedicarboxylic acid, benzenetricarboxylic acid, nitrilotriacetic acid, and tricarballylic acid, by amide bonds to 1-amino-omega-(hydroxyamino)alkanes to provide the polyhydroxamates 1-5. The required protected (hydroxyamino)alkanes 8, 16, and 21 were prepared by different routes. 1-Amino-3-[(benzyloxy)amino]propane di-p-toluenesulfonate (8) was prepared from the N-protected aminopropanol 6 by oxidation to the aldehyde, formation of the substituted oxime, and reduction with NaBH3CN followed by deprotection of the Boc group. The pentyl derivatives 16 and 21 were made by direct alkylation with either benzyl acetohydroxamate or N-carbobenzoxy-O-benzylhydroxylamine. In Escherichia coli RW193 most of the analogues behaved nutritionally as ferrichrome. However, in E. coli AN193, a mutant lacking the ferrichrome receptor, capacity to use other natural siderophores was retained while response to all analogues was lost.

  11. Divalent metal transporter 1 (DMT1) in the brain: implications for a role in iron transport at the blood-brain barrier, and neuronal and glial pathology

    PubMed Central

    Skjørringe, Tina; Burkhart, Annette; Johnsen, Kasper Bendix; Moos, Torben

    2015-01-01

    Iron is required in a variety of essential processes in the body. In this review, we focus on iron transport in the brain and the role of the divalent metal transporter 1 (DMT1) vital for iron uptake in most cells. DMT1 locates to cellular membranes and endosomal membranes, where it is a key player in non-transferrin bound iron uptake and transferrin-bound iron uptake, respectively. Four isoforms of DMT1 exist, and their respective characteristics involve a complex cell-specific regulatory machinery all controlling iron transport across these membranes. This complexity reflects the fine balance required in iron homeostasis, as this metal is indispensable in many cell functions but highly toxic when appearing in excess. DMT1 expression in the brain is prominent in neurons. Of serious dispute is the expression of DMT1 in non-neuronal cells. Recent studies imply that DMT1 does exist in endosomes of brain capillary endothelial cells denoting the blood-brain barrier. This supports existing evidence that iron uptake at the BBB occurs by means of transferrin-receptor mediated endocytosis followed by detachment of iron from transferrin inside the acidic compartment of the endosome and DMT1-mediated pumping iron into the cytosol. The subsequent iron transport across the abluminal membrane into the brain likely occurs by ferroportin. The virtual absent expression of transferrin receptors and DMT1 in glial cells, i.e., astrocytes, microglia and oligodendrocytes, suggest that the steady state uptake of iron in glia is much lower than in neurons and/or other mechanisms for iron uptake in these cell types prevail. PMID:26106291

  12. Lunar articulated remote transportation system

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The students of the Florida A&M/Florida State University College of Engineering continued their design from 1988 to 1989 on a first generation lunar transportation vehicle for use on the surface of the Moon between the years 2010 and 2020. Attention is focused on specific design details on all components of the Lunar Articulated Remote Transportation System (Lunar ARTS). The Lunar ARTS will be a three-cart, six-wheeled articulated vehicle. Its purpose will be the transportation of astronauts and/or materials for excavation purposes at a short distance from the base (37.5 km). The power system includes fuel cells for both the primary system and the back-up system. The vehicle has the option of being operated in a manned or unmanned mode. The unmanned mode includes stereo imaging with signal processing for navigation. For manned missions the display console is a digital readout displayed on the inside of the astronaut's helmet. A microprocessor is also on board the vehicle. Other components of the vehicle include a double wishbone/flexible hemispherical wheel suspension; chassis; a steering system; motors; seat retraints; heat rejection systems; solar flare protection; dust protection; and meteoroid protection. A one-quarter scale dynamic model has been built to study the dynamic behavior of the vehicle. The dynamic model closely captures the mechanical and electrical details of the total design.

  13. Lunar articulated remote transportation system

    NASA Technical Reports Server (NTRS)

    Beech, Geoffrey; Conley, Gerald; Diaz, Claudine; Dimella, Timothy; Dodson, Pete; Hykin, Jeff; Richards, Byron; Richardson, Kroy; Shetzer, Christie; Vandyke, Melissa

    1990-01-01

    A first generation lunar transportation vehicle was designed for use on the surface of the Moon between the years 2010 and 2020. Attention is focussed on specific design details on all components of the Lunar Articulated Remote Transportation System (Lunar ARTS). The Lunar ARTS will be a three cart, six-wheeled articulated vehicle. It's purpose will be for the transportation of astronauts and/or materials for excavation purposes at a short distance from the base (37.5 kilometers). The power system includes fuel cells for both the primary system and the back-up system. The vehicle has the option of being operated in a manned or unmanned mode. The unmanned mode includes stereo imaging with signal processing for navigation. For manned missions the display console is a digital readout displayed on the inside of the asronaut's helmet. A microprocessor is also on board the vehicle. Other components of the vehicle include: a double wishbone/flexible hemispherical wheel suspension; chassis; a steering system; motors; seat restraints, heat rejection systems; solar flare protection; dust protection; and meteoroid protection. A one-quarter scale dynamic model was built to study the dynamic behavior of the vehicle. The dynamic model closely captures the mechanical and electrical details of the total design.

  14. Integrated Intermodal Passenger Transportation System

    NASA Technical Reports Server (NTRS)

    Klock, Ryan; Owens, David; Schwartz, Henry; Plencner, Robert

    2012-01-01

    Modern transportation consists of many unique modes of travel. Each of these modes and their respective industries has evolved independently over time, forming a largely incoherent and inefficient overall transportation system. Travelers today are forced to spend unnecessary time and efforts planning a trip through varying modes of travel each with their own scheduling, pricing, and services; causing many travelers to simply rely on their relatively inefficient and expensive personal automobile. This paper presents a demonstration program system to not only collect and format many different sources of trip planning information, but also combine these independent modes of travel in order to form optimal routes and itineraries of travel. The results of this system show a mean decrease in inter-city travel time of 10 percent and a 25 percent reduction in carbon dioxide emissions over personal automobiles. Additionally, a 55 percent reduction in carbon dioxide emissions is observed for intra-city travel. A conclusion is that current resources are available, if somewhat hidden, to drastically improve point to point transportation in terms of time spent traveling, the cost of travel, and the ecological impact of a trip. Finally, future concepts are considered which could dramatically improve the interoperability and efficiency of the transportation infrastructure.

  15. Cytosolic Iron-Sulfur Cluster Assembly (CIA) System: Factors, Mechanism, and Relevance to Cellular Iron Regulation*

    PubMed Central

    Sharma, Anil K.; Pallesen, Leif J.; Spang, Robert J.; Walden, William E.

    2010-01-01

    FeS cluster biogenesis is an essential process in virtually all forms of life. Complex protein machineries that are conserved from bacteria through higher eukaryotes facilitate assembly of the FeS cofactor in proteins. In the last several years, significant strides have been made in our understanding of FeS cluster assembly and the functional overlap of this process with cellular iron homeostasis. This minireview summarizes the present understanding of the cytosolic iron-sulfur cluster assembly (CIA) system in eukaryotes, with a focus on information gained from studies in budding yeast and mammalian systems. PMID:20522543

  16. Cytosolic iron-sulfur cluster assembly (CIA) system: factors, mechanism, and relevance to cellular iron regulation.

    PubMed

    Sharma, Anil K; Pallesen, Leif J; Spang, Robert J; Walden, William E

    2010-08-27

    FeS cluster biogenesis is an essential process in virtually all forms of life. Complex protein machineries that are conserved from bacteria through higher eukaryotes facilitate assembly of the FeS cofactor in proteins. In the last several years, significant strides have been made in our understanding of FeS cluster assembly and the functional overlap of this process with cellular iron homeostasis. This minireview summarizes the present understanding of the cytosolic iron-sulfur cluster assembly (CIA) system in eukaryotes, with a focus on information gained from studies in budding yeast and mammalian systems.

  17. Preliminary Hazards Assessment: Iron disulfide purification system

    SciTech Connect

    1991-07-30

    A process for the purification (washing) of iron disulfide (FeS{sub 2}) powder is conducted in the Northeast corner (Area 353) of the main plant building (Building 100). This location is about 130 feet from the fenced boundary of the Partnership School/Child Development Center. In the first steps of the process, raw iron disulfide powder is ground and separated by particle size. The ground and sized powder is then purified in a three-step acid washing process using both hydrochloric acid (HCI) and hydrofluoric (HF) acid. The iron disulfide process is an intermittent batch process conducted four to eight times a year. This study is a Preliminary Hazards Assessment (PHA) to assess the hazards associated with the iron disulfide process. This is a preliminary study and will be used to determine if additional safety analysis is necessary. The scope of the PHA includes assessment of the process steps of grinding, size classification, and purification. The purpose is to identify major hazards and determine if the current and newly added safeguards are adequate for operation. The PHA also lists recommendations for additional safety features that should be added to reduce the risks of operation.

  18. Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers

    NASA Astrophysics Data System (ADS)

    Wood, Deborah; Crocket, Kirsty; Brand, Tim; Stutter, Marc; Wilson, Clare; Schröder, Christian

    2016-04-01

    Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers Wood, D.A¹, Crocket, K², Brand, T², Stutter, M³, Wilson, C¹ & Schröder, C¹ ¹Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA ²Scottish Association for Marine Science, University of the Highlands and Islands, Dunbeg, Oban, PA37 1QA ³James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH The biogeochemical iron cycle exerts significant control on the carbon cycle¹. Iron is a limiting nutrient in large areas of the world's oceans and its bioavailability controls CO2 uptake by marine photosynthesizing microorganisms. While atmospheric iron inputs to the open ocean have been extensively measured, global river inputs have likely been underestimated because most major world rivers exhibit extensive iron removal by flocculation and sedimentation during seawater mixing. Iron minerals and organic matter mutually stabilise each other², which results in a 'rusty carbon sink' in sediments³ on the one hand but may also enhance transport beyond the salinity gradient on the other. Humic-rich, high latitude rivers have a higher iron-carrying capacity⁴‑⁶ but are underrepresented in iron flux calculations. The West Coast sea lochs in Scotland are fed by predominantly peatland drainage catchments, and the rivers entering the sea lochs carry a high load of organic matter. The short distance between many of these catchments and the coastal ocean facilitates source-to-sea research investigating transport, fate and mineralogy of iron-bearing colloids providing a good analogue for similar high latitude fjordic systems. We use SeaFAST+ICP-MS and Mössbauer spectroscopy to survey trace metal concentrations, with emphasis on iron concentrations, speciation and mineralogy, across salinity gradients. In combination with ultra-filtration techniques, this allows

  19. Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers

    NASA Astrophysics Data System (ADS)

    Wood, Deborah; Crocket, Kirsty; Brand, Tim; Stutter, Marc; Wilson, Clare; Schröder, Christian

    2016-04-01

    Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers Wood, D.A¹, Crocket, K², Brand, T², Stutter, M³, Wilson, C¹ & Schröder, C¹ ¹Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA ²Scottish Association for Marine Science, University of the Highlands and Islands, Dunbeg, Oban, PA37 1QA ³James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH The biogeochemical iron cycle exerts significant control on the carbon cycle¹. Iron is a limiting nutrient in large areas of the world's oceans and its bioavailability controls CO2 uptake by marine photosynthesizing microorganisms. While atmospheric iron inputs to the open ocean have been extensively measured, global river inputs have likely been underestimated because most major world rivers exhibit extensive iron removal by flocculation and sedimentation during seawater mixing. Iron minerals and organic matter mutually stabilise each other², which results in a 'rusty carbon sink' in sediments³ on the one hand but may also enhance transport beyond the salinity gradient on the other. Humic-rich, high latitude rivers have a higher iron-carrying capacity⁴-⁶ but are underrepresented in iron flux calculations. The West Coast sea lochs in Scotland are fed by predominantly peatland drainage catchments, and the rivers entering the sea lochs carry a high load of organic matter. The short distance between many of these catchments and the coastal ocean facilitates source-to-sea research investigating transport, fate and mineralogy of iron-bearing colloids providing a good analogue for similar high latitude fjordic systems. We use SeaFAST+ICP-MS and Mössbauer spectroscopy to survey trace metal concentrations, with emphasis on iron concentrations, speciation and mineralogy, across salinity gradients. In combination with ultra-filtration techniques, this allows

  20. Docosahexaenoic acid enhances iron uptake by modulating iron transporters and accelerates apoptotic death in PC12 cells.

    PubMed

    Schonfeld, Eldi; Yasharel, Ilanit; Yavin, Ephraim; Brand, Annette

    2007-10-01

    The effect of docosahexaenoic acid (DHA; 22:6 n-3) on Fe(2+)-mediated and/or H(2)O(2)-mediated oxidative stress (OS) was investigated in a PC12 pheochromocytoma cell line in the presence or absence of 50 ng/ml nerve growth factor (NGF). DHA-supplemented cells showed enhanced Fe(2+)-induced cell damage as evident by increased lipid peroxides formation (10-fold) and reduced neutral red (NR) dye uptake in a NGF-independent fashion. DHA caused a nearly 10-fold increase in free iron uptake in NGF-treated cells and doubled iron uptake in nondifferentiated cells. DHA-enrichment induced an elevation in the transferrin receptor protein in the nondifferentiated cells whereas NGF-treatment led to a substantial increase in the ubiquitous divalent metal ion transporter 1 (DMT-1) as detected by mRNA levels using qRT-PCR. The mechanism of action of DHA to accelerate cell death may be associated with the externalization of amino-phosphoglycerides (PG) species of which, increased ethanolamine plasmalogen levels, may be essential for cell rescue as noted in NGF-treated PC12 cells. PMID:17551831

  1. THE EFFECT OF WATER CHEMISTRY ON THE PROPERTIES OF IRON PARTICLES AND IRON SUSPENSIONS

    EPA Science Inventory

    The structure and properties of iron colloids in aquatic systems is important in understanding their behavior in environmental and engineering systems. For example the adsorption of contaminants onto iron colloids and subsequent transport through ground water aquifers and surface...

  2. High-Throughput Screening Assay for Inhibitors of TonB-Dependent Iron Transport.

    PubMed

    Hanson, Mathew; Jordan, Lorne D; Shipelskiy, Yan; Newton, Salete M; Klebba, Phillip E

    2016-03-01

    The TonB-dependent Gram-negative bacterial outer membrane protein FepA actively transports the siderophore ferric enterobactin (FeEnt) into the periplasm. We developed a high-throughput screening (HTS) assay that observes FeEnt uptake through FepA in living Escherichia coli, by monitoring fluorescence quenching that occurs upon binding of FeEnt, and then unquenching as the bacteria deplete it from solution by transport. We optimized the labeling and spectroscopic methods to screen for inhibitors of TonB-dependent iron uptake through the outer membrane. The assay works like a molecular switch that is on in the presence of TonB activity and off in its absence. It functions in 96-well microtiter plates, in a variety of conditions, with Z factors of 0.8-1.0. TonB-dependent iron transport is energy dependent, and the inhibitory effects of the metabolic inhibitors carbonyl cyanide m-chlorophenylhydrazone, 2,4-dinitrophenol, azide, cyanide, and arsenate on FeEnt uptake were readily detected by the assay. Because iron acquisition is a determinant of bacterial pathogenesis, HTS with this method may identify inhibitors that block TonB function and constitute novel therapeutics against infectious disease caused by Gram-negative bacteria.

  3. DIVALENT METAL TRANSPORTER-1 REGULATION BY IRON AND VANADIUM MODULATES HYDROGEN PEROXIDE-INDUCED DNA DAMAGE IN LUNG CELLS

    EPA Science Inventory

    The divalent metal transporter-1 (DMT1) participates in the detoxification of metals that can damage lung epithelium. Elevated iron levels increase the expression of DMT1 in bronchial epithelial cells stimulating its uptake and storage in ferritin, thus making iron unavailable t...

  4. Siderophore-mediated iron transport correlates with the presence of specific iron-regulated proteins in the outer membrane of Rhizobium meliloti.

    PubMed Central

    Reigh, G; O'Connell, M

    1993-01-01

    A universal chemical assay used to detect the production of siderophores in a range of Rhizobium strains showed that production is strain specific. Iron nutrition bioassays carried out on Rhizobium meliloti strains to determine cross-utilization of their siderophores showed that R. meliloti 2011, 220-5, and 220-3 could each use the siderophores produced by the other two but not the siderophore produced by R. meliloti DM4 (and vice versa). Mutants of R. meliloti 2011 and 220-5 defective in siderophore production were isolated by Tn5-mob mutagenesis. The Tn5-mob-containing EcoRI fragment of mutant R. meliloti 220-5-1 was cloned into pUC19. By using this fragment as a probe, the presence of a homologous region was observed in R. meliloti 2011 and 220-3 but not in R. meliloti DM4. A complementing cosmid from a gene bank of R. meliloti 2011 was identified by using the same probe. Introduction of this cosmid into R. meliloti 102F34, a strain not producing a siderophore, resulted in the ability of this strain to produce a siderophore and also in the ability to utilize the siderophores produced by R. meliloti 2011, 220-5, and 220-3 but not the siderophore produced by R. meliloti DM4. A comparative analysis of the outer membrane proteins prepared from iron-deficient cultures of R. meliloti 102F34 and 102F34 harboring the cosmid revealed the presence, in the latter, of a low-iron-induced outer membrane protein corresponding to a low-iron-induced protein in R. meliloti 2011, 220-5, and 220-3. This protein is not present in R. meliloti DM4. The results suggest that R. meliloti 2011, 220-5, and 220-3 produce siderophores that are identical or sufficiently similar in structure to be transported by the membrane transport system of each strain while also indicating that utilization of a particular siderophore is correlated with the presence of specific outer membrane proteins. Images PMID:8416915

  5. System and method for making metallic iron with reduced CO.sub.2 emissions

    SciTech Connect

    Kiesel, Richard F; Englund, David J; Schlichting, Mark; Meehan, John; Crouch, Jeremiah; Wilson, Logan

    2014-10-14

    A method and system for making metallic iron nodules with reduced CO.sub.2 emissions is disclosed. The method includes: assembling a linear hearth furnace having entry and exit portions, at least a conversion zone and a fusion zone, and a moving hearth adapted to move reducible iron bearing material through the furnace on contiguous hearth sections; assembling a shrouded return substantially free of air ingress extending adjacent at least the conversion and fusion zones of the furnace through which hearth sections can move from adjacent the exit portion to adjacent the entry portion of the furnace; transferring the hearth sections from the furnace to the shrouded return adjacent the exit portion; reducing reducible material in the linear hearth furnace to metallic iron nodules; and transporting gases from at least the fusion zone to the shrouded return to heat the hearth sections while in the shrouded return.

  6. Method and system for producing metallic iron nuggets

    SciTech Connect

    Iwasaki, Iwao; Kiesel, Richard F.; Englund, David J; Hendrickson, Dave

    2012-12-18

    A method and system for producing metallic iron nuggets may include providing multiple layers of agglomerates, such as briquettes, balls and extrusions, of a reducible mixture of reducing material (such as carbonaceous material) and of a reducible iron bearing material (such as iron oxide) on a hearth material layer (such as carbonaceous material) and providing a coarse overlayer of carbonaceous material over at least some of the agglomerates. Heating the agglomerates of reducible mixture to 1425.degree. C. or 1400.degree. C. or 1375.degree. C. results in formation of an intermediate product of one or more metallic iron nuggets, which may have a sulfur content of less than 0.03%, and slag, which may have less than 5% mass MgO, which may have a ratio of percent by weight sulfur in the slag over percent by weight sulfur in the metallic nuggets of at least about 12 or at least about 15.

  7. Regulation of iron uptake and transport by transferrin in Caco-2 cells, an intestinal cell line.

    PubMed

    Alvarez-Hernandez, X; Smith, M; Glass, J

    1994-06-22

    Caco-2 cells grown in bicameral chambers, a model of intestinal epithelial iron transport (Biochim. Biophys. Acta (1991) 1070, 205-208), were used to study the effect of apo-transferrin (apo-Tf) in the basal chamber on 59Fe uptake from the apical surface, intracellular 59Fe distribution, and 59Fe transport into the basal chamber. Caco-2 cells were grown with varying amounts of iron to achieve cells that were either iron-deficient (FeD), or normal iron status (FeN), or iron-loaded (FeH). The effect of apo-Tf was most marked in FeD cells with the transport of 59Fe from 1 microM 59Fe-ascorbate on the apical side to the basal chamber measured as (22.2 +/- 3.0) x 10(4), (8.2 +/- 0.6) x 10(4), and (2.7 +/- 0.4) x 10(4) atoms 59Fe/cell/min in the presence of apo-Tf, BSA, and no added protein, respectively. Unexpectedly in FeD cells total 59Fe uptake (i.e., both 59Fe in the cells and that transported into the basal chamber) was decreased by basolateral apo-Tf with total uptake of (2.6 +/- 0.3) x 10(5), (4.8 +/- 0.6) x 10(5), and (4.8 +/- 0.7) x 10(5) atoms/cell/min with apo-Tf, BSA, and no additions, respectively. Analysis of intracellular 59Fe by isoelectrofocusing in polyacrylamide gels demonstrated 59Fe migrating both with a basic pI and with the pI values of ferritin (Ft) at a ratio of 200:1 (basic pI moiety: ferritin) in FeD cells. The presence of Tf further decreased the small amount of 59Fe in Ft. These studies demonstrate that basolateral Tf affects the apical uptake of 59Fe, the intracellular distribution of 59Fe, and the transport of 59Fe across intestinal epithelium, the latter effect occurring even when cellular content of ferritin is high.

  8. Iron acquisition in Vibrio cholerae.

    PubMed

    Wyckoff, Elizabeth E; Mey, Alexandra R; Payne, Shelley M

    2007-06-01

    Vibrio cholerae, the causative agent of cholera, has an absolute requirement for iron and must obtain this element in the human host as well as in its varied environmental niches. It has multiple systems for iron acquisition, including the TonB-dependent transport of heme, the endogenous siderophore vibriobactin and several siderophores that are produced by other microorganisms. There is also a Feo system for the transport of ferrous iron and an ABC transporter, Fbp, which transports ferric iron. There appears to be at least one additional high affinity iron transport system that has not yet been identified. In iron replete conditions, iron acquisition genes are repressed by Fur. Fur also represses the synthesis of a small, regulatory RNA, RyhB, which negatively regulates genes for iron-containing proteins involved in the tricarboxylic acid cycle and respiration as well as genes for motility and chemotaxis. The redundancy in iron transport systems has made it more difficult to determine the role of individual systems in vivo and in vitro, but it may reflect the overall importance of iron in the growth and survival of V. cholerae.

  9. Field-scale transport and transformation of carboxymethylcellulose-stabilized nano zero-valent iron.

    PubMed

    Johnson, Richard L; Nurmi, James T; O'Brien Johnson, Graham S; Fan, Dimin; O'Brien Johnson, Reid L; Shi, Zhenqing; Salter-Blanc, Alexandra J; Tratnyek, Paul G; Lowry, Gregory V

    2013-02-01

    The fate of nano zerovalent iron (nZVI) during subsurface injection was examined using carboxymethylcellulose (CMC) stabilized nZVI in a very large three-dimensional physical model aquifer with detailed monitoring using multiple, complementary detection methods. A fluorescein tracer test in the aquifer plus laboratory column data suggested that the very-aggressive flow conditions necessary to achieve 2.5 m of nZVI transport could be obtained using a hydraulically constrained flow path between injection and extraction wells. However, total unoxidized nZVI was transported only about 1 m and <2% of the injected nZVI concentration reached that distance. The experimental data also indicated that groundwater flow changed during injection, likely due to hydrogen bubble formation, which diverted the nZVI away from the targeted flow path. The leading edge of the iron plume became fully oxidized during transport. However, within the plume, oxidation of nZVI decreased in a fashion consistent with progressive depletion of aquifer "reductant demand". To directly quantify the extent of nZVI transport, a spectrophotometric method was developed, and the results indicated that deployment of unoxidized nZVI for groundwater remediation will likely be difficult.

  10. Research on advanced transportation systems

    NASA Astrophysics Data System (ADS)

    Nagai, Hirokazu; Hashimoto, Ryouhei; Nosaka, Masataka; Koyari, Yukio; Yamada, Yoshio; Noda, Keiichirou; Shinohara, Suetsugu; Itou, Tetsuichi; Etou, Takao; Kaneko, Yutaka

    1992-08-01

    An overview of the researches on advanced space transportation systems is presented. Conceptual study is conducted on fly back boosters with expendable upper stage rocket systems assuming a launch capacity of 30 tons and returning to the launch site by the boosters, and prospect of their feasibility is obtained. Reviews are conducted on subjects as follows: (1) trial production of 10 tons sub scale engines for the purpose of acquiring hardware data and picking up technical problems for full scale 100 tons thrust engines using hydrocarbon fuels; (2) development techniques for advanced liquid propulsion systems from the aspects of development schedule, cost; (3) review of conventional technologies, and common use of component; (4) oxidant switching propulsion systems focusing on feasibility of Liquefied Air Cycle Engine (LACE) and Compressed Air Cycle Engine (CACE); (5) present status of slosh hydrogen manufacturing, storage, and handling; (6) construction of small high speed dynamometer for promoting research on mini pump development; (7) hybrid solid boosters under research all over the world as low-cost and clean propulsion systems; and (8) high performance solid propellant for upper stage and lower stage propulsion systems.

  11. Influence of the electronic structure on the transport properties of some iron pnictides

    NASA Astrophysics Data System (ADS)

    Rullier-Albenque, Florence

    2016-01-01

    An important feature of the iron-based pnictides is their multi-band electronic structure with both electron and hole bands at the Fermi level. The size of these pockets can be changed by different types of substitution, resulting in a variety of original magnetic and electronic properties. The contributions of both types of carriers will thus have important consequences on the evolution of the transport properties versus temperature and doping. It has been pointed out that Hund's rule interaction plays a prominent role in the physics of these compounds by allowing a strong orbital differentiation between the 3d Fe orbitals. As a result, a description in terms of more or less correlated electrons was proposed and may have important consequences on the scattering lifetimes of the different carriers. Finally, the presence of very flat bands at the Fermi level may induce a semiconductor-like behavior, with a change in carrier concentration with temperature. In this paper, we will review the evolution of transport properties with chemical doping/substitution in iron pnictides. We will more particularly focus on the 122 family (Ba(Sr,Ca)Fe2As2) and the 111 LiFeAs compound for which sizeable single crystals required for transport measurements are available. The combined resistivity, Hall effect and magnetoresistance data will be analyzed in association with electronic structure calculations, angle-resolved photoemission measurements and quantum oscillations. In spite of the strong interplay between antiferromagnetism and superconductivity in most part of their phase diagram, direct signatures of spin fluctuations are difficult to identify in the transport properties of iron pnictides. We will show that measurements of the longitudinal magnetoresistance provide a powerful tool for studying the coupling between the charge carriers and the spin degrees of freedom.

  12. The chloroplast permease PIC1 regulates plant growth and development by directing homeostasis and transport of iron.

    PubMed

    Duy, Daniela; Stübe, Roland; Wanner, Gerhard; Philippar, Katrin

    2011-04-01

    The membrane-spanning protein PIC1 (for permease in chloroplasts 1) in Arabidopsis (Arabidopsis thaliana) was previously described to mediate iron transport across the inner envelope membrane of chloroplasts. The albino phenotype of pic1 knockout mutants was reminiscent of iron-deficiency symptoms and characterized by severely impaired plastid development and plant growth. In addition, plants lacking PIC1 showed a striking increase in chloroplast ferritin clusters, which function in protection from oxidative stress by sequestering highly reactive free iron in their spherical protein shell. In contrast, PIC1-overexpressing lines (PIC1ox) in this study rather resembled ferritin loss-of-function plants. PIC1ox plants suffered from oxidative stress and leaf chlorosis, most likely originating from iron overload in chloroplasts. Later during growth, plants were characterized by reduced biomass as well as severely defective flower and seed development. As a result of PIC1 protein increase in the inner envelope membrane of plastids, flower tissue showed elevated levels of iron, while the content of other transition metals (copper, zinc, manganese) remained unchanged. Seeds, however, specifically revealed iron deficiency, suggesting that PIC1 overexpression sequestered iron in flower plastids, thereby becoming unavailable for seed iron loading. In addition, expression of genes associated with metal transport and homeostasis as well as photosynthesis was deregulated in PIC1ox plants. Thus, PIC1 function in plastid iron transport is closely linked to ferritin and plastid iron homeostasis. In consequence, PIC1 is crucial for balancing plant iron metabolism in general, thereby regulating plant growth and in particular fruit development.

  13. Use of electrophoresis for transporting nano-iron in porous media.

    PubMed

    Jones, Edward H; Reynolds, David A; Wood, A Lynn; Thomas, David G

    2011-01-01

    Research has been conducted to evaluate if electrophoresis could transport surface stabilized nanoscale zero-valent iron (nZVI) through fine grained sand with the intent of remediating a contaminant in situ. The experimental procedure involved determining the transport rates of polymer modified nZVI and hematite in fine grained sands under an applied electrical gradient under different physical and chemical conditions. Results indicated transport of polymer modified nZVI and hematite can be accomplished by electrophoresis, with rates found to be much higher than diffusion alone and comparable to those predicted by electrokinetic theory. This study indicates there is potential for this method to deliver polymer modified nZVI into contaminated zones within fine grained sands for the purpose of remediation. PMID:21449091

  14. Influence of permeability on nanoscale zero-valent iron particle transport in saturated homogeneous and heterogeneous porous media.

    PubMed

    Strutz, Tessa J; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-09-01

    Nanoscale zero-valent iron (NZVI) particles can be used for in situ groundwater remediation. The spatial particle distribution plays a very important role in successful and efficient remediation, especially in heterogeneous systems. Initial sand permeability (k 0) influences on spatial particle distributions were investigated and quantified in homogeneous and heterogeneous systems within the presented study. Four homogeneously filled column experiments and a heterogeneously filled tank experiment, using different median sand grain diameters (d 50), were performed to determine if NZVI particles were transported into finer sand where contaminants could be trapped. More NZVI particle retention, less particle transport, and faster decrease in k were observed in the column studies using finer sands than in those using coarser sands, reflecting a function of k 0. In heterogeneous media, NZVI particles were initially transported and deposited in coarse sand areas. Increasing the retained NZVI mass (decreasing k in particle deposition areas) caused NZVI particles to also be transported into finer sand areas, forming an area with a relatively homogeneous particle distribution and converged k values despite the different grain sizes present. The deposited-particle surface area contribution to the increasing of the matrix surface area (θ) was one to two orders of magnitude higher for finer than coarser sand. The dependency of θ on d 50 presumably affects simulated k changes and NZVI distributions in numerical simulations of NZVI injections into heterogeneous aquifers. The results implied that NZVI can in principle also penetrate finer layers.

  15. Disorders associated with systemic or local iron overload: from pathophysiology to clinical practice.

    PubMed

    Sebastiani, Giada; Pantopoulos, Kostas

    2011-10-01

    In healthy subjects, the rate of dietary iron absorption, as well as the amount and distribution of body iron are tightly controlled by hepcidin, the iron regulatory hormone. Disruption of systemic iron homeostasis leads to pathological conditions, ranging from anemias caused by iron deficiency or defective iron traffic, to iron overload (hemochromatosis). Other iron-related disorders are caused by misregulation of cellular iron metabolism, which results in local accumulation of the metal in mitochondria. Brain iron overload is observed in neurodegenerative disorders. Secondary hemochromatosis develops as a complication of another disease. For example, repeated blood transfusions, a standard treatment of various anemias characterized by ineffective erythropoiesis, promote transfusional siderosis, while chronic liver diseases are often associated with mild to moderate secondary iron overload. In this critical review, we discuss pathophysiological and clinical aspects of all types of iron metabolism disorders (265 references).

  16. System and method for producing metallic iron

    DOEpatents

    Bleifuss, Rodney L; Englund, David J; Iwasaki, Iwao; Fosnacht, Donald R; Brandon, Mark M; True, Bradford G

    2013-09-17

    A hearth furnace for producing metallic iron material has a furnace housing having a drying/preheat zone, a conversion zone, a fusion zone, and optionally a cooling zone, the conversion zone is between the drying/preheat zone and the fusion zone. A moving hearth is positioned within the furnace housing. A hood or separation barrier within at least a portion of the conversion zone, fusion zone or both separates the fusion zone into an upper region and a lower region with the lower region adjacent the hearth and the upper region adjacent the lower region and spaced from the hearth. An injector introduces a gaseous reductant into the lower region adjacent the hearth. A combustion region may be formed above the hood or separation barrier.

  17. System and method for producing metallic iron

    DOEpatents

    Bleifuss, Rodney L.; Englund, David J.; Iwasaki, Iwao; Fosnacht, Donald R.; Brandon, Mark M.; True, Bradford G.

    2012-01-17

    A hearth furnace 10 for producing metallic iron material has a furnace housing 11 having a drying/preheat zone 12, a conversion zone 13, a fusion zone 14, and optionally a cooling zone 15, the conversion zone 13 is between the drying/preheat zone 12 and the fusion zone 14. A moving hearth 20 is positioned within the furnace housing 11. A hood or separation barrier 30 within at least a portion of the conversion zone 13, fusion zone 14 or both separates the fusion zone 14 into an upper region and a lower region with the lower region adjacent the hearth 20 and the upper region adjacent the lower region and spaced from the hearth 20. An injector introduces a gaseous reductant into the lower region adjacent the hearth 20. A combustion region may be formed above the hood or separation barrier.

  18. A vacuolar iron transporter in tulip, TgVit1, is responsible for blue coloration in petal cells through iron accumulation.

    PubMed

    Momonoi, Kazumi; Yoshida, Kumi; Mano, Shoji; Takahashi, Hideyuki; Nakamori, Chihiro; Shoji, Kazuaki; Nitta, Akira; Nishimura, Mikio

    2009-08-01

    Blue color in flowers is due mainly to anthocyanins, and a considerable part of blue coloration can be attributed to metal-complexed anthocyanins. However, the mechanism of metal ion transport into vacuoles and subsequent flower color development has yet to be fully explored. Previously, we studied the mechanism of blue color development specifically at the bottom of the inner perianth in purple tulip petals of Tulipa gesneriana cv. Murasakizuisho. We found that differences in iron content were associated with the development of blue- and purple-colored cells. Here, we identify a vacuolar iron transporter in T. gesneriana (TgVit1), and characterize the localization and function of this transporter protein in tulip petals. The amino acid sequence of TgVit1 is 85% similar that of the Arabidopsis thaliana vacuolar iron transporter AtVIT1, and also showed similarity to the AtVIT1 homolog in yeast, Ca(2+)-sensitive cross-complementer 1 (CCC1). The gene TgVit1 was expressed exclusively in blue-colored epidermal cells, and protein levels increased with increasing mRNA expression and blue coloration. Transient expression experiments revealed that TgVit1 localizes to the vacuolar membrane, and is responsible for the development of the blue color in purple cells. Expression of TgVit1 in yeast rescued the growth defect of ccc1 mutant cells in the presence of high concentrations of FeSO(4). Our results indicate that TgVit1 plays an essential role in blue coloration as a vacuolar iron transporter in tulip petals. These results suggest a new role for involvement of a vacuolar iron transporter in blue flower color development.

  19. The Role of the Iron Transporter ABCB7 in Refractory Anemia with Ring Sideroblasts

    PubMed Central

    Nikpour, Maryam; Pushkaran, Beena; Fidler, Carrie; Cattan, Helen; Littlewood, Tim J.; Malcovati, Luca; Della Porta, Matteo G.; Jädersten, Martin; Killick, Sally; Giagounidis, Aristoteles; Bowen, David; Hellström-Lindberg, Eva; Cazzola, Mario; Wainscoat, James S.

    2008-01-01

    Refractory Anemia with Ring Sideroblasts (RARS) is an acquired myelodysplastic syndrome (MDS) characterized by an excess iron accumulation in the mitochondria of erythroblasts. The pathogenesis of RARS and the cause of this unusual pattern of iron deposition remain unknown. We considered that the inherited X-linked sideroblastic anemia with ataxia (XLSA/A) might be informative for the acquired disorder, RARS. XLSA/A is caused by partial inactivating mutations of the ABCB7 ATP-binding cassette transporter gene, which functions to enable transport of iron from the mitochondria to the cytoplasm. Furthermore, ABCB7 gene silencing in HeLa cells causes an accumulation of iron in the mitochondria. We have studied the role of ABCB7 in RARS by DNA sequencing, methylation studies, and gene expression studies in primary CD34+ cells and in cultured erythroblasts. The DNA sequence of the ABCB7 gene is normal in patients with RARS. We have investigated ABCB7 gene expression levels in the CD34+ cells of 122 MDS cases, comprising 35 patients with refractory anemia (RA), 33 patients with RARS and 54 patients with RA with excess blasts (RAEB), and in the CD34+ cells of 16 healthy controls. We found that the expression levels of ABCB7 are significantly lower in the RARS group. RARS is thus characterized by lower levels of ABCB7 gene expression in comparison to other MDS subtypes. Moreover, we find a strong relationship between increasing percentage of bone marrow ring sideroblasts and decreasing ABCB7 gene expression levels. Erythroblast cell cultures confirm the low levels of ABCB7 gene expression levels in RARS. These data provide an important link between inherited and acquired forms of sideroblastic anemia and indicate that ABCB7 is a strong candidate gene for RARS. PMID:18398482

  20. Radioisotope thermoelectric generator transport trailer system

    SciTech Connect

    Ard, K.E.; King, D.A.; Leigh, H.; Satoh, J.A.

    1995-01-20

    The Radioisotope Thermoelectric Generator (RTG) Transportation System, designated as System 100, comprises four major systems. The four major systems are designated as the Packaging System (System 120), Trailer System (System 140), Operations and Ancillary Equipment System (System 160), and Shipping and Receiving Facility Transport System (System 180). Packaging System (System 120), including the RTG packaging is licensed (regulatory) hardware; it is certified by the U.S. Department of Energy to be in accordance with Title 10, {ital Code} {ital of} {ital Federal} {ital Regulations}, Part 71 (10 CFR 71). System 140, System 160, and System 180 are nonlicensed (nonregulatory) hardware. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}

  1. Vesicular transport systems in fungi

    PubMed Central

    Rodrigues, Marcio L; Nosanchuk, Joshua D; Schrank, Augusto; Vainstein, Marilene H; Casadevall, Arturo; Nimrichter, Leonardo

    2014-01-01

    Canonical and unconventional mechanisms of secretion in many eukaryotic cells are relatively well known. In contrast to the situation in animal cells, mechanisms of secretion in fungi must include the capacity for trans-cell wall passage of macromolecules to the extracellular space. Although these mechanisms remain somewhat elusive, several studies in recent years have suggested that vesicular transport is required for trans-cell wall secretion of large molecules. Several fungal molecules, including proteins, lipids, polysaccharides and pigments, are released to the extracellular space in vesicles. In pathogenic fungi, a number of these vesicular components are associated with fungal virulence. Indeed, extracellular vesicles produced by fungi can interfere with the immunomodulatory activity of host cells. Fungal vesicles share many functional aspects with mammalian exosomes and extracellular vesicles produced by bacteria, plants and protozoa, but their cellular origin remains unknown. Here, we discuss the involvement of vesicular transport systems in fungal physiology and pathogenesis, making parallels with the mammalian, bacterial, protozoan and plant cell literature. PMID:22082294

  2. Use of a molecular decoy to segregate transport from antigenicity in the FrpB iron transporter from Neisseria meningitidis.

    PubMed

    Saleem, Muhammad; Prince, Stephen M; Rigby, Stephen E J; Imran, Muhammad; Patel, Hema; Chan, Hannah; Sanders, Holly; Maiden, Martin C J; Feavers, Ian M; Derrick, Jeremy P

    2013-01-01

    FrpB is an outer membrane transporter from Neisseria meningitidis, the causative agent of meningococcal meningitis. It is a member of the TonB-dependent transporter (TBDT) family and is responsible for iron uptake into the periplasm. FrpB is subject to a high degree of antigenic variation, principally through a region of hypervariable sequence exposed at the cell surface. From the crystal structures of two FrpB antigenic variants, we identify a bound ferric ion within the structure which induces structural changes on binding which are consistent with it being the transported substrate. Binding experiments, followed by elemental analysis, verified that FrpB binds Fe(3+) with high affinity. EPR spectra of the bound Fe(3+) ion confirmed that its chemical environment was consistent with that observed in the crystal structure. Fe(3+) binding was reduced or abolished on mutation of the Fe(3+)-chelating residues. FrpB orthologs were identified in other Gram-negative bacteria which showed absolute conservation of the coordinating residues, suggesting the existence of a specific TBDT sub-family dedicated to the transport of Fe(3+). The region of antigenic hypervariability lies in a separate, external sub-domain, whose structure is conserved in both the F3-3 and F5-1 variants, despite their sequence divergence. We conclude that the antigenic sub-domain has arisen separately as a result of immune selection pressure to distract the immune response from the primary transport function. This would enable FrpB to function as a transporter independently of antibody binding, by using the antigenic sub-domain as a 'molecular decoy' to distract immune surveillance.

  3. Influence of electrolyte and voltage on the direct current enhanced transport of iron nanoparticles in clay.

    PubMed

    Gomes, Helena I; Dias-Ferreira, Celia; Ribeiro, Alexandra B; Pamukcu, Sibel

    2014-03-01

    Zero valent iron nanoparticles (nZVI) transport for soil and groundwater remediation is slowed down or halted by aggregation or fast depletion in the soil pores. Direct electric current can enhance the transport of nZVI in low permeability soils. However operational factors, including pH, oxidation-reduction potential (ORP), voltage and ionic strength of the electrolyte can play an important role in the treatment effectiveness. Experiments were conducted to enhance polymer coated nZVI mobility in a model low permeability soil medium (kaolin clay) using low direct current. Different electrolytes of varying ionic strengths and initial pH and high nZVI concentrations were applied. Results showed that the nZVI transport is enhanced by direct current, even considering concentrations typical of field application that favor nanoparticle aggregation. However, the factors considered (pH, ORP, voltage and electrolyte) failed to explain the iron concentration variation. The electrolyte and its ionic strength proved to be significant for pH and ORP measured during the experiments, and therefore will affect aggregation and fast oxidation of the particles.

  4. The yersiniabactin transport system is critical for the pathogenesis of bubonic and pneumonic plague.

    PubMed

    Fetherston, Jacqueline D; Kirillina, Olga; Bobrov, Alexander G; Paulley, James T; Perry, Robert D

    2010-05-01

    Iron acquisition from the host is an important step in the pathogenic process. While Yersinia pestis has multiple iron transporters, the yersiniabactin (Ybt) siderophore-dependent system plays a major role in iron acquisition in vitro and in vivo. In this study, we determined that the Ybt system is required for the use of iron bound by transferrin and lactoferrin and examined the importance of the Ybt system for virulence in mouse models of bubonic and pneumonic plague. Y. pestis mutants unable to either transport Ybt or synthesize the siderophore were both essentially avirulent via subcutaneous injection (bubonic plague model). Surprisingly, via intranasal instillation (pneumonic plague model), we saw a difference in the virulence of Ybt biosynthetic and transport mutants. Ybt biosynthetic mutants displayed an approximately 24-fold-higher 50% lethal dose (LD(50)) than transport mutants. In contrast, under iron-restricted conditions in vitro, a Ybt transport mutant had a more severe growth defect than the Ybt biosynthetic mutant. Finally, a Delta pgm mutant had a greater loss of virulence than the Ybt biosynthetic mutant, indicating that the 102-kb pgm locus encodes a virulence factor, in addition to Ybt, that plays a role in the pathogenesis of pneumonic plague.

  5. Phase stable RF transport system

    DOEpatents

    Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.

    1992-01-01

    An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.

  6. Classical transport in disordered systems

    NASA Astrophysics Data System (ADS)

    Papaioannou, Antonios

    This thesis reports on the manifestation of structural disorder on molecular transport and it consists of two parts. Part I discusses the relations between classical transport and the underlying structural complexity of the system. Both types of molecular diffusion, namely Gaussian and non- Gaussian are presented and the relevant time regimes are discussed. In addition the concept of structural universality is introduced and connected with the diffusion metrics. One of the most robust techniques for measuring molecular mean square displacements is magnetic resonance. This method requires encoding and subsequently reading out after an experimentally controlled time, a phase φ to the spins using magnetic field gradients. The main limitation for probing short diffusion lengths L(t) ˜ 1micro m with magnetic resonance is the requirement to encode and decode the phase φ in very short time intervals. Therefore, to probe such displacements a special probe was developed equipped with a gradient coil capable of delivering magnetic field gradients of approximately 90 G/cmA . The design of the probe is reported. Part I also includes a discussion of experiments of transport in two qualitatively different disordered phantoms and reports on a direct observation of universality in one-dimension. The results reveal the universal power law scaling of the diffusion coefficient at the long-time regime and illustrate the essence of structural universality by experimentally determining the structure correlation function of the phantoms. In addition, the scaling of the diffusive permeability of the phantoms with respect to the pore size is investigated. Additional work presented includes a detailed study of adsorption of methane gas in Vycor disordered glass. The techniques described in Part I of this thesis are widely used for measuring structural parameters of porous media, such as the surface-to-volume ratio or diffusive permeability. Part II of this thesis discusses the

  7. Manned transportation system study - Evaluation of candidate transportation architectures

    NASA Technical Reports Server (NTRS)

    Lance, Nicholas; Klemer, R.; Sooter, C.

    1992-01-01

    The overall evaluation process, the tool developed to perform the evaluation, and the evaluation results in determining the right approach to meet the nation's mannned transportation needs are presented. To address the various considerations, architecture sets consisting of the candidate transportation systems are constructed. As this methodology results in multiple architectures to examine, an architecture evaluation tool was developed to facilitate the evaluation of the architecture attribute values from the system values of the attributes.

  8. Sustainability Analysis of Innovative Transport System

    NASA Astrophysics Data System (ADS)

    Meiere, Ieva; Bazbauers, Gatis

    2011-01-01

    The focus of the research is to develop a new approach to transport solution based on the use of a conveyortype system and to compare the environmental impact of the new system with the existing ones. The new transport system consists of a conveyor driven by an electric motor, with a wind power plant supplying electricity, hydrogen storage and a fuel cell for matching the wind power production with the motor load. The research tasks included the evaluation of the consumption of fossil fuels and the associated environmental impact of existing transport system and a comparison with energy consumption and associated environmental impact of the new system. The energy balance of the conveyor transport system was modelled on an hourly basis by using the EnergyPLAN computer program [1] which allows to analyze a combination of intermittent renewable energy technologies, storage and transport systems. The results show that the existing transport system has greater impact on the environment than the proposed one.

  9. Modeling Polymer Stabilized Nano-scale Zero Valent Iron Transport Experiments in Porous Media to Understand the Transport Behavior

    NASA Astrophysics Data System (ADS)

    Mondal, P.; Krol, M.; Sleep, B. E.

    2015-12-01

    A wide variety of groundwater contaminants can be treated with nano-scale zero valent iron (nZVI). However, delivery of nZVI in the subsurface to the treatment zones is challenging as the bare nZVI particles have a higher tendency to agglomerate. The subsurface mobility of nZVI can be enhanced by stabilizing nZVI with polymer, such as carboxymethyl cellulose (CMC). In this study, numerical simulations were conducted to evaluate CMC stabilized nZVI transport behavior in porous media. The numerical simulations were based on a set of laboratory-scale transport experiments that were conducted in a two-dimensional water-saturated glass-walled sandbox (length - 55 cm; height - 45 cm; width - 1.4 cm), uniformly packed with silica sand. In the transport experiments: CMC stabilized nZVI and a non-reactive dye tracer Lissamine Green B (LGB) were used; water specific discharge and CMC concentration were varied; movements of LGB, and CMC-nZVI in the sandbox were tracked using a camera, a light source and a dark box. The concentrations of LGB, CMC, and CMC-nZVI at the sandbox outlet were analyzed. A 2D multiphase flow and transport model was applied to simulate experimental results. The images from LGB dye transport experiments were used to determine the pore water velocities and media permeabilities in various layers in the sand box. These permeability values were used in the subsequent simulations of CMC-nZVI transport. The 2D compositional simulator, modified to include colloid filtration theory (CFT), treated CMC as a solute and nZVI as a colloid. The simulator included composition dependent viscosity to account for CMC injection and mixing, and attachment efficiency as a fitting parameter for nZVI transport modeling. In the experiments, LGB and CMC recoveries were greater than 95%; however, CMC residence time was significantly higher than the LGB residence time and the higher CMC concentration caused higher pressure drops in the sandbox. The nZVI recovery was lower than 40

  10. Transport of non-newtonian suspensions of highly concentrated micro- and nanoscale iron particles in porous media: a modeling approach.

    PubMed

    Tosco, Tiziana; Sethi, Rajandrea

    2010-12-01

    The use of zerovalent iron micro- and nanoparticles (MZVI and NZVI) for groundwater remediation is hindered by colloidal instability, causing aggregation (for NZVI) and sedimentation (for MZVI) of the particles. Transportability of MZVI and NZVI in porous media was previously shown to be significantly increased if viscous shear-thinning fluids (xanthan gum solutions) are used as carrier fluids. In this work, a novel modeling approach is proposed and applied for the simulation of 1D flow and transport of highly concentrated (20 g/L) non-newtonian suspensions of MZVI and NZVI, amended with xanthan gum (3 g/L). The coupled model is able to simulate the flow of a shear thinning fluid including the variable apparent viscosity arising from changes in xanthan and suspended iron particle concentrations. The transport of iron particles is modeled using a dual-site approach accounting for straining and physicochemical deposition/release phenomena. A general formulation for reversible deposition is herein proposed, that includes all commonly applied dynamics (linear attachment, blocking, ripening). Clogging of the porous medium due to deposition of iron particles is modeled by tying porosity and permeability to deposited iron particles. The numerical model proved to adequately fit the transport tests conducted using both MZVI and NZVI and can develop into a powerful tool for the design and the implementation of full scale zerovalent iron applications.

  11. Transport of carboxymethyl cellulose stabilized nanoscale zerovalent iron in porous media, an experimental and modeling study

    NASA Astrophysics Data System (ADS)

    Sleep, Brent; Mondal, Pulin; Furbacher, Paul; Cui, Ziteng; Krol, Magdalena

    2015-04-01

    Nano-scale zero valent iron (nZVI) is capable of reacting with a wide variety of groundwater contaminants. Therefore, during the last decade nZVI has received significant attention for application in subsurface remediation, particularly for sites contaminated with chlorinated compounds and heavy metals. However, due to agglomeration of the nZVI, delivery into the contaminated subsurface zones is challenging. Polymer stabilization of nZVI can enhance the mobility of the iron particles in the subsurface. In this study, a set of laboratory-scale transport experiments and numerical simulations were performed to evaluate carboxymethyl cellulose (CMC) polymer stabilized nZVI transport in porous media. Experiments were conducted in a two-dimensional water-saturated lab-scale glass-walled sandbox, uniformly packed with silica sand, to identify the effects of water specific discharge and CMC concentration on nZVI transport. Experiments were also performed using Lissamine Green B (LGB) dye as a non-reactive tracer to characterize the sand media. The CMC stabilized nZVI was synthesized freshly at a concentration of 1000 mg/L before each transport experiment. The synthesized CMC-nZVI mixture was characterized using transmission electron microscopy, dynamic light scattering, and UV-visual spectrophotometry. The movement of the LGB dye and nZVI in the sandbox during the experiments was monitored using time-lapsed images captured using a light source and a dark box. The transport of LGB, CMC, and CMC-nZVI was evaluated through analysis of the breakthrough curves at the outlet and the retained nZVI in the sandbox. The LGB, CMC, and nZVI transport was also modeled using a multiphase flow and transport model considering LGB and CMC as solutes, and nZVI as a colloid. Analysis of the breakthrough data showed that the mass recovery of LGB and CMC was greater than 95 % indicating conservative transport in silica sand. However, the mean residence time of CMC was significantly higher than

  12. 20. SIMILAR TO THE SYSTEM INSTALLED IN THE GREY IRON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. SIMILAR TO THE SYSTEM INSTALLED IN THE GREY IRON FOUNDRY, MALLEABLE WORKERS FILLED MOLDS TRAVELING ON A CONVEYOR FROM LADLES ATTACHED TO OVERHEAD RAILS WHILE THEY STOOD ON A PLATFORM MOVING AT THE SAME SPEED AS THE CONVEYOR, CA. 1950 - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  13. Deficiency of a alpha-1-antitrypsin influences systemic iron homeostasis

    EPA Science Inventory

    Abstract Background: There is evidence that proteases and anti-proteases participate in the iron homeostasis of cells and living systems. We tested the postulate that alpha-1 antitrypsin (A1AT) polymorphism and the consequent deficiency of this anti-protease in humans are asso...

  14. Non-equilibrium Transport in Carbon based Adsorbate Systems

    NASA Astrophysics Data System (ADS)

    Fürst, Joachim; Brandbyge, Mads; Stokbro, Kurt; Jauho, Antti-Pekka

    2007-03-01

    We have used the Atomistix Tool Kit(ATK) and TranSIESTA[1] packages to investigate adsorption of iron atoms on a graphene sheet. The technique of both codes is based on density functional theory using local basis sets[2], and non-equilibrium Green's functions (NEGF) to calculate the charge distribution under external bias. Spin dependent electronic structure calculations are performed for different iron coverages. These reveal adsorption site dependent charge transfer from iron to graphene leading to screening effects. Transport calculations show spin dependent scattering of the transmission which is analysed obtaining the transmission eigenchannels for each spin type. The phenomena of electromigration of iron in these systems at finite bias will be discussed, estimating the so-called wind force from the reflection[3]. [1] M. Brandbyge, J.-L. Mozos, P. Ordejon, J. Taylor, and K. Stokbro. Physical Review B (Condensed Matter and Materials Physics), 65(16):165401/11-7, 2002. [2] Jose M. Soler, Emilio Artacho, Julian D. Gale, Alberto Garcia, Javier Junquera, Pablo Ordejon, and Daniel Sanchez-Portal. Journal of Physics Condensed Matter, 14(11):2745-2779, 2002. [3] Sorbello. Theory of electromigration. Solid State Physics, 1997.

  15. Method and system for producing metallic iron nuggets

    SciTech Connect

    Iwasaki, Iwao; Lindgren, Andrew J.; Kiesel, Richard F.

    2013-06-25

    Method and system for producing metallic nuggets includes providing reducible mixture of reducing material (such as carbonaceous material) and reducible iron bearing material (such as iron oxide) that may be arranged in discrete portions, such as mounds or briquettes, on at least a portion of a hearth material layer (such as carbonaceous material). A coarse overlayer of carbonaceous material may be provided over at least some of the discrete portions. Heating the reducible mixture to 1425.degree. C. or 1400.degree. C. or 1375.degree. C. results in formation of an intermediate product of one or more metallic iron nuggets, which may have a sulfur content of less than 0.03%, and slag, which may have less than 5% mass MgO, which may have a ratio of percent by weight sulfur in the slag over percent by weight sulfur in the metallic nuggets of at least about 12 or at least about 15.

  16. Arabidopsis copper transport protein COPT2 participates in the cross talk between iron deficiency responses and low-phosphate signaling.

    PubMed

    Perea-García, Ana; Garcia-Molina, Antoni; Andrés-Colás, Nuria; Vera-Sirera, Francisco; Pérez-Amador, Miguel A; Puig, Sergi; Peñarrubia, Lola

    2013-05-01

    Copper and iron are essential micronutrients for most living organisms because they participate as cofactors in biological processes, including respiration, photosynthesis, and oxidative stress protection. In many eukaryotic organisms, including yeast (Saccharomyces cerevisiae) and mammals, copper and iron homeostases are highly interconnected; yet, such interdependence is not well established in higher plants. Here, we propose that COPT2, a high-affinity copper transport protein, functions under copper and iron deficiencies in Arabidopsis (Arabidopsis thaliana). COPT2 is a plasma membrane protein that functions in copper acquisition and distribution. Characterization of the COPT2 expression pattern indicates a synergic response to copper and iron limitation in roots. We characterized a knockout of COPT2, copt2-1, that leads to increased resistance to simultaneous copper and iron deficiencies, measured as reduced leaf chlorosis and improved maintenance of the photosynthetic apparatus. We propose that COPT2 could play a dual role under iron deficiency. First, COPT2 participates in the attenuation of copper deficiency responses driven by iron limitation, possibly to minimize further iron consumption. Second, global expression analyses of copt2-1 versus wild-type Arabidopsis plants indicate that low-phosphate responses increase in the mutant. These results open up new biotechnological approaches to fight iron deficiency in crops.

  17. OsABCB14 functions in auxin transport and iron homeostasis in rice (Oryza sativa L.).

    PubMed

    Xu, Yanxia; Zhang, Saina; Guo, Haipeng; Wang, Suikang; Xu, Ligen; Li, Chuanyou; Qian, Qian; Chen, Fan; Geisler, Markus; Qi, Yanhua; Jiang, De An

    2014-07-01

    Members of the ATP Binding Cassette B/Multidrug-Resistance/P-glyco-protein (ABCB/MDR/PGP) subfamily were shown to function primarily in Oryza sativa (rice) auxin transport; however, none of the rice ABCB transporters have been functionally characterized. Here, we describe that a knock-down of OsABCB14 confers decreased auxin concentrations and polar auxin transport rates, conferring insensitivity to 2,4-dichlorophenoxyacetic acid (2,4-D) and indole-3-acetic acid (IAA). OsABCB14 displays enhanced specific auxin influx activity in yeast and protoplasts prepared from rice knock-down alleles. OsABCB14 is localized at the plasma membrane, pointing to an important directionality under physiological conditions. osabcb14 mutants were surprisingly found to be insensitive to iron deficiency treatment (-Fe). Their Fe concentration is higher and upregulation of Fe deficiency-responsive genes is lower in osabcb14 mutants than in wild-type rice (Nipponbare, NIP). Taken together, our results strongly support the role of OsABCB14 as an auxin influx transporter involved in Fe homeostasis. The functional characterization of OsABCB14 provides insights in monocot auxin transport and its relationship to Fe nutrition.

  18. Brain iron homeostasis.

    PubMed

    Moos, Torben

    2002-11-01

    transferrin were, however, restricted to areas situated in close proximity to the ventricular and pial surfaces. In particular, transferrin injected into the ventricles was never observed in regions distant from the CSF. It was concluded that choroid plexus-derived transferrin is not likely to play a significant role for binding and transporting iron in the brain interstitium. Transferrin secretion from oligodendrocytes probably plays the key role in this process. In the third part of the thesis, the uptake of iron by neurons devoid of projections beyond the blood-brain barrier and glia is addressed. Given the fact that the demonstration of plasma proteins in brain sections can be hampered by several methodological factors, a mapping of the cellular distribution of transferrin in the brain was performed employing extensive use of tissue-processing and staining protocols. In order to aid in the understanding of cellular iron uptake in the intact brain, attempts were made to identify iron, transferrin, and transferrin receptors at the light microscopic level. Consistent with the widespread distribution of transferrin receptors in neurons, the ligand transferrin was also found in neurons throughout the CNS. When examined at high resolution, transferrin was found to be distributed to the cytoplasm of neurons, exhibiting a dotted appearance, which is probably consistent with a distribution in the endosomallysosomal system. In contrast to the consistent presence of transferrin receptors on neurons, it was not possible to detect transferrin receptors on glial cells. Related to these observations, the presence of non-transferrin-bound iron in the brain suggests that glial cells may take it up by a mechanism that does not involve the transferrin receptor. The widespread distribution of ferritin in glial cells clearly indicates that the glial cells acquire iron. Dietary iron-overload did not change the distribution of transferrin receptors or ferritin in the brain. By contrast, iron

  19. Transport in closed nanoscale systems

    NASA Astrophysics Data System (ADS)

    Bushong, Neil

    2005-03-01

    An alternative way to describe electrical transport in nanoscale systems has been recently proposed where two large but finite charged electrodes discharge across a nanoscale junction (M. Di Ventra and T. Todorov, J. Phys. Cond. Matt. 16, 8025 (2004)). We have applied this concept to describe the dynamics of a finite quasi-one dimensional gold wire using both a simple tight-binding model and time-dependent density-functional theory. After an initial transient, a quasi-steady state sets in whose lifetime increases with system size. This quasi-steady state is due to the wave properties of the electron wavefunctions and the resultant uncertainty principle and is established without inelastic effects. The corresponding current-voltage characteristics at steady state are in very good agreement with those calculated from the static scattering approach. We discuss local electron distributions, electrostatic potentials, and local resistivity dipoles formed at the quasi-steady state and compare these findings with the static open-boundary problem. A relation between information entropy and electron dynamics is discussed. Work supported by NSF.

  20. Existing and emerging mechanisms for transport of iron and manganese to the brain.

    PubMed

    Malecki, E A; Devenyi, A G; Beard, J L; Connor, J R

    1999-04-15

    The metals iron (Fe) and manganese (Mn) are essential for normal functioning of the brain. This review focuses on recent developments in the literature pertaining to Fe and Mn transport. These metals are treated together because they appear to share several transport mechanisms. In addition, several neurological diseases such as Alzheimer's Disease, Parkinson's Disease, and Huntington's Disease are all associated with Fe mismanagement in the brain, particularly in the striatum and basal ganglia. Similarly, Mn accumulation in brain also appears to target the same brain regions. Therefore, stringent regulation of the concentration of these metals in the brain is essential. The homeostatic mechanisms for these metals must be understood in order to design neurotoxicity prevention strategies. PMID:10777372

  1. Influence of copper depletion on iron uptake mediated by SFT, a stimulator of Fe transport.

    PubMed

    Yu, J; Wessling-Resnick, M

    1998-03-20

    We recently identified a novel factor involved in cellular iron assimilation called SFT or Stimulator of Fe Transport (Gutierrez, J. A., Yu, J., Rivera, S., and Wessling-Resnick, M. (1997) J. Cell Biol. 149, 895-905). When stably expressed in HeLa cells, SFT was found to stimulate the uptake of both transferrin- and nontransferrin-bound Fe (iron). Assimilation of nontransferrin-bound Fe by HeLa cells stably expressing SFT was time- and temperature-dependent; both the rate and extent of uptake was enhanced relative to the activity of control nontransfected cells. Although the apparent Km for Fe uptake was unaffected by expression of SFT (5.6 versus 5.1 microM measured for control), the Vmax of transport was increased from 7.0 to 14.7 pmol/min/mg protein. Transport mediated by SFT was inhibitable by diethylenetriaminepentaacetic acid and ferrozine, Fe3+- and Fe2+-specific chelators. Because cellular copper status is known to influence Fe assimilation, we investigated the effects of Cu (copper) depletion on SFT function. After 4 days of culture in Cu-deficient media, HeLa cell Cu,Zn superoxide dismutase activity was reduced by more than 60%. Both control cells and cells stably expressing SFT displayed reduced Fe uptake as well; levels of transferrin-mediated import fell by approximately 80%, whereas levels of nontransferrin-bound Fe uptake were approximately 50% that of Cu-replete cells. The failure of SFT expression to stimulate Fe uptake above basal levels in Cu-depleted cells suggests a critical role for Cu in SFT function. A current model for both transferrin- and nontransferrin-bound Fe uptake involves the function of a ferrireductase that acts to reduce Fe3+ to Fe2+, with subsequent transport of the divalent cation across the membrane bilayer. SFT expression did not enhance levels of HeLa cell surface reductase activity; however, Cu depletion was found to reduce endogenous activity by 60%, suggesting impaired ferrireductase function may account for the influence

  2. Metal transports and enrichments in iron depositions hosted in basaltic rocks. II: Metal rich fluids and Fe origin

    NASA Astrophysics Data System (ADS)

    Zhang, Ronghua; Zhang, Xuetong; Hu, Shumin

    2015-12-01

    This study focuses on revealing the mechanism of metal transport, enrichment and Fe origin of iron deposition during water basalt interactions occurred in basaltic rocks. Observations of the iron deposits (anhydrite-magnetite-pyroxene type deposits) hosted in K-rich basaltic rocks in the Mesozoic volcanic area of the Middle-Lower Yangtze River valley, China, indicate that the mechanism of metal transport and enrichment for those deposits are significant objective to scientists, and the Fe origin problem is not well resolved. Here the metal transport, enrichment and iron origin have been investigated in high temperature experiments of water basaltic interactions. These deposits were accompanying a wide zone with metal alteration. The effects of hydrothermal alteration on major rock-forming element concentrations in basaltic rock were investigated by systematically comparing the chemical compositions of altered rocks with those of fresh rocks. In the deposits, these metals are distributed throughout altered rocks that exhibit vertical zoning from the deeper to the shallow. Then, combined with the investigations of the metal-alterations, we performed kinetic experiments of water-basaltic rock interactions using flow-through reactors in open systems at temperatures from 20 °C to 550 °C, 23-34 MPa. Release rates for the rock-forming elements from the rocks have been measured. Experiments provide the release rates for various elements at a large temperature range, and indicate that the dissolution rates (release rates) for various elements vary with temperature. Si, Al, and K have high release rates at temperatures from 300 °C to 500 °C; the maximum release rates (RMX) for Si are reached at temperatures from 300 °C to 400 °C. The RMXs for Ca, Mg, and Fe are at low temperatures from 20 °C to 300 °C. Results demonstrate that Fe is not released from 400 °C to 550 °C, and indicate that when deep circling fluids passed through basaltic rocks, Fe was not mobile, and

  3. THE EFFECT OF CHLORIDE AND ORTHOPHOSPHATE ON THE RELEASE OF IRON FROM A DRINKING WATER DISTRIBUTION SYSTEM CAST IRON PIPE

    EPA Science Inventory

    "Colored water" describes the appearance of drinking water that contains suspended particulate iron although the actual suspension color may be light yellow to red depending on water chemistry and particle properties. The release of iron from distribution system materials such a...

  4. THE EFFECT OF CHLORIDE AND ORTHOPHOSPHATE ON THE RELEASE OF IRON FROM DRINKING WATER DISTRIBUTION SYSTEM CAST IRON MAIN

    EPA Science Inventory

    “Colored water” resulting from suspended iron particles is a common drinking water consumer complaint which is largely impacted by water chemistry. A bench scale study, performed on a 90 year-old corroded cast-iron pipe section removed from a drinking water distribution system, w...

  5. THE EFFECT OF CHLORIDE AND ORTHOPHOSPHATE ON THE RELEASE OF IRON FROM A DRINKING WATER DISTRIBUTION SYSTEM CAST IRON PIPE

    EPA Science Inventory

    Colored water" describes the appearance of drinking water that contains suspended particulate iron although the actual suspension color may be light yellow to red depending on water chemistry and particle properties. The release of iron from distribution system materials such as...

  6. GEOCHEMISTRY OF SULFUR IN IRON CORROSION SCALES FOUND IN DRINKING WATER DISTRIBUTION SYSTEMS

    EPA Science Inventory

    Iron-sulfur geochemistry is important in many natural and engineered environments, including drinking water systems. In the anaerobic environment beneath scales of corroding iron drinking water distribution system pipes, sulfate reducing bacteria (SRB) produce sulfide from natu...

  7. Integration of Genome-Scale Metabolic Nodels of Iron-Reducing Bacteria With Subsurface Flow and Geochemical Reactive Transport Models

    NASA Astrophysics Data System (ADS)

    Scheibe, T. D.; Mahadevan, R.; Fang, Y.; Garg, S.; Long, P. E.; Lovley, D. M.

    2008-12-01

    Several field and laboratory experiments have demonstrated that the growth and activity of iron-reducing bacteria can be stimulated in many subsurface environments by amendment of groundwater with a soluble electron donor. Under strong iron-reducing conditions, these organisms mediate reactions that can impact a wide range of subsurface contaminants including chlorinated hydrocarbons, metals, and radionuclides. Therefore there is strong interest in in-situ bioremediation as a potential technology for cleanup of contaminated aquifers. To evaluate and design bioremediation systems, as well as to evaluate the viability of monitored natural attenuation as an alternative, quantitative models of biogeochemically reactive transport are needed. To date, most such models represent microbial activity in terms of kinetic rate (e.g., Monod- type) formulations. Such models do not account for fundamental changes in microbial functionality (such as utilization of alternative respiratory pathways) that occur as the result of spatial and temporal variations in the geochemical environment experienced by microorganisms. Constraint-based genome-scale in silico models of microbial metabolism present an alternative to simplified rate formulations that provide flexibility to account for changes in microbial function in response to local geochemical conditions. We have developed and applied a methodology for coupling a constraint-based in silico model of Geobacter sulfurreducens with a conventional model of groundwater flow, transport, and geochemical reaction. Two uses of the in silico model are tested: 1) incorporation of modified microbial growth yield coefficients based on the in silico model, and 2) variation of reaction rates in a reactive transport model based on in silico modeling of a range of local geochemical conditions. Preliminary results from this integrated model will be presented.

  8. Expression, purification and functional reconstitution of FeoB, the ferrous iron transporter from Pseudomonas aeruginosa.

    PubMed

    Seyedmohammad, Saeed; Born, Diana; Venter, Henrietta

    2014-09-01

    The FeoB Fe(II) transporter from the drug resistant pathogen, Pseudomonas aeruginosa is essential for ferrous iron transport and is implicated in virulence and biofilm development. Hence it is an attractive target for the development of new anti-infective drugs. FeoB is an intriguing protein that consists of a cytosolic N-terminal GTPase domain and an integral membrane domain which most likely acts as ferrous iron permease. Characterisation of FeoB is critical for developing therapeutics aimed at inhibiting this protein. However, structural and functional analysis of FeoB is hampered by the lack of high yield homogenously pure protein which is monodisperse, stable and active in solution. Here we describe the optimised procedure for the recombinant expression of FeoB from P. aeruginosa and provide an evaluation of the most favourable purification, pH and detergent conditions. The functional reconstitution of FeoB in liposomes is also described. This represents the first detailed procedure for obtaining a pure, active and stable FeoB solution in milligram quantities which would be amenable to biochemical, biophysical and structural studies.

  9. Expression, purification and functional reconstitution of FeoB, the ferrous iron transporter from Pseudomonas aeruginosa.

    PubMed

    Seyedmohammad, Saeed; Born, Diana; Venter, Henrietta

    2014-09-01

    The FeoB Fe(II) transporter from the drug resistant pathogen, Pseudomonas aeruginosa is essential for ferrous iron transport and is implicated in virulence and biofilm development. Hence it is an attractive target for the development of new anti-infective drugs. FeoB is an intriguing protein that consists of a cytosolic N-terminal GTPase domain and an integral membrane domain which most likely acts as ferrous iron permease. Characterisation of FeoB is critical for developing therapeutics aimed at inhibiting this protein. However, structural and functional analysis of FeoB is hampered by the lack of high yield homogenously pure protein which is monodisperse, stable and active in solution. Here we describe the optimised procedure for the recombinant expression of FeoB from P. aeruginosa and provide an evaluation of the most favourable purification, pH and detergent conditions. The functional reconstitution of FeoB in liposomes is also described. This represents the first detailed procedure for obtaining a pure, active and stable FeoB solution in milligram quantities which would be amenable to biochemical, biophysical and structural studies. PMID:24993789

  10. Transport of nano zero-valent iron supported by mesoporous silica microspheres in porous media.

    PubMed

    Yang, Zhangmei; Qiu, Xinhong; Fang, Zhanqiang; Pokeung, Tsang

    2015-01-01

    Effective in situ remediation of groundwater requires the successful delivery of reactive iron particles through sand. However, the agglomeration of nano zero-valent iron (NZVI) particles limits the migration distance, which inhibits their usefulness. In the study described herein, NZVI supported by mesoporous silica microspheres covered with FeOOH (SiO2@FeOOH@Fe) was synthesized, and its mobility was demonstrated on the basis of transport in porous media. Degradation of decabromodiphenyl ether (BDE209) was more efficient by SiO2@FeOOH@Fe than by 'bare' NZVI. Breakthrough curves and mass recovery showed the mobility of SiO2@FeOOH@Fe in granular media was better than that of bare NZVI. It increased greatly in the presence of natural organic matter (NOM) and decreased when high Ca2+ and Mg2+ concentrations were encountered. Analysis of the transport data on the basis of filtration theory showed diffusion to be the main mechanism for particle removal in silicon sand. Increasing the NOM may decrease agglomeration of the grains of sand, which has a positive effect on the mobility of SiO2@FeOOH@Fe. Presumably, increasing the concentrations of Ca2+ and Mg2+ compresses the diffuse double layer of SiO2@FeOOH@Fe, resulting in a reduction of mobility.

  11. Transport of iron oxide nanoparticles in saturated porous media: a large-scale 3D study

    NASA Astrophysics Data System (ADS)

    Velimirovic, Milica; Schmid, Doris; Micić, Vesna; Miyajima, Kumiko; Klaas, Norbert; Braun, Jürgen; Bosch, Julian; Meckenstock, Rainer; von der Kammer, Frank; Hofmann, Thilo

    2016-04-01

    Iron oxide nanoparticles (FeOxNp) have a high potential as electron acceptor for in situ microbial oxidation of a wide range of recalcitrant groundwater contaminants (Bosch et al., 2010). Tosco et al. (2012) reported on high colloidal stability of FeOxNp dispersed in water, their low deposition behavior, and consequently improved transport in column experiments compared to extensively studied zerovalent iron nanoparticles. However, determination of FeOxNp transport behavior at the field-relevant conditions has not been done before. The present work is aimed to evaluate different complementary methods for detection, quantification and transport characterization of FeOxNp in a large-scale three-dimensional (3D) model aquifer. Prior to that, batch-scale experiments were performed in order to elucidate the potential of the selected methods for direct and indirect characterization and detection of FeOxNp. Direct methods included measurements of particle size distribution, particle concentration, Fetot content and turbidity of the FeOxNp suspension. Indirect methods included measurements of particle zeta potential, as well as TOC content and pH of the FeOxNp suspension. The results of the batch experiments indicated that the most suitable approach for detecting and quantifying FeOxNp was measuring Fetot content and suspension turbidity, as well as particle size determined using dynamic light scattering principle. These complementary methods were further applied in a large-scale 3D study containing medium and coarse sand in order to 1) assess the transport of FeOxNp in saturated porous medium during injection (VFeOx = 6 m3, cparticle = 20 g/L, Qinj = 0.7 m3/h), and 2) illustrate their spatial distribution after injection. The outcomes of the large-scale 3D study confirmed that FeOxNp transport can be successfully investigated applying complementary methods. Monitoring data including Fetot content, turbidity and particle size showed the transport of particles towards the

  12. A National MagLev Transportation System

    NASA Technical Reports Server (NTRS)

    Wright, Michael R.

    2003-01-01

    The case for a national high-speed magnetic-levitation (MagLev) transportation system is presented. Focus is on current issues facing the country, such as national security, the economy, transportation, technology, and the environment. NASA s research into MagLev technology for launch assist is also highlighted. Further, current socio-cultural norms regarding motor-vehicle-based transportation systems are questioned in light of the problems currently facing the U.S. The multidisciplinary benefits of a long-distance MagLev system support the idea that such a system would be an important element of a truly multimodal U.S. transportation infrastructure.

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

    NASA Astrophysics Data System (ADS)

    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

  14. Intelligent transportation systems applications to transportation demand management. Final report

    SciTech Connect

    Wallace, C.E.; Kilpatrick, A.K.; Schneider, K.R.

    1996-04-01

    The primary focus of Intelligent Transportation Systems (ITS) is on traffic management systems, advanced traveler information systems, and so forth. Further, ITS is most readily identified with such systems urban areas because the majority of transportation management infrastructures and traffic congestion exist in these densely populated areas. ITS however, must not be restricted to supply-side options. Transportation demand management (TDM) can potentially have a significant impact on congestion, energy conservation and the environment. This paper presents the results of a preliminary study of ITS implications for TDM. It reports on a number of related projects undertaken around the U.S. and in Canada. It offers recommendations for expanding ITS involvement in TDM.

  15. Enhanced transport of Si-coated nanoscale zero-valent iron particles in porous media.

    PubMed

    HonetschlÄgerová, Lenka; Janouškovcová, Petra; Kubal, Martin

    2016-01-01

    Laboratory column experiments were conducted to evaluate the effect of previously described silica coating method on the transport of nanoscale zero-valent iron (nZVI) in porous media. The silica coating method showed the potential to prevent the agglomeration of nZVI. Transport experiments were conducted using laboratory-scale sand-packed columns at conditions that were very similar of natural groundwater. Transport properties of non-coated and silica-coated nZVI are investigated in columns of 40 cm length, which were filled with porous media. A suspension was injected in three different Fe particle concentrations (100, 500, and 1000 mg/L) at flow 5  mL/min. Experimental results were compared using nanoparticle attachment efficiency and travel distances which were calculated by classical particle filtration theory. It was found that non-coated particles were essentially immobile in porous media. In contrast, silica-coated particles showed significant transport distances at the tested conditions. Results of this study suggest that silica can increase nZVI mobility in the subsurface.

  16. Transport and viability of Escherichia coli cells in clean and iron oxide coated sand following coating with silver nanoparticles.

    PubMed

    Ngwenya, Bryne T; Curry, Philip; Kapetas, Leon

    2015-08-01

    A mechanistic understanding of processes controlling the transport and viability of bacteria in porous media is critical for designing in situ bioremediation and microbiological water decontamination programs. We investigated the combined influence of coating sand with iron oxide and silver nanoparticles on the transport and viability of Escherichia coli cells under saturated conditions. Results showed that iron oxide coatings increase cell deposition which was generally reversed by silver nanoparticle coatings in the early stages of injection. These observations are consistent with short-term, particle surface charge controls on bacteria transport, where a negatively charged surface induced by silver nanoparticles reverses the positive charge due to iron oxide coatings, but columns eventually recovered irreversible cell deposition. Silver nanoparticle coatings significantly increased cell inactivation during transit through the columns. However, when viability data is normalised to volume throughput, only a small improvement in cell inactivation is observed for silver nanoparticle coated sands relative to iron oxide coating alone. This counterintuitive result underscores the importance of net surface charge in controlling cell transport and inactivation and implies that the extra cost for implementing silver nanoparticle coatings on porous beds coated with iron oxides may not be justified in designing point of use water filters in low income countries. PMID:26042624

  17. Transport and viability of Escherichia coli cells in clean and iron oxide coated sand following coating with silver nanoparticles.

    PubMed

    Ngwenya, Bryne T; Curry, Philip; Kapetas, Leon

    2015-08-01

    A mechanistic understanding of processes controlling the transport and viability of bacteria in porous media is critical for designing in situ bioremediation and microbiological water decontamination programs. We investigated the combined influence of coating sand with iron oxide and silver nanoparticles on the transport and viability of Escherichia coli cells under saturated conditions. Results showed that iron oxide coatings increase cell deposition which was generally reversed by silver nanoparticle coatings in the early stages of injection. These observations are consistent with short-term, particle surface charge controls on bacteria transport, where a negatively charged surface induced by silver nanoparticles reverses the positive charge due to iron oxide coatings, but columns eventually recovered irreversible cell deposition. Silver nanoparticle coatings significantly increased cell inactivation during transit through the columns. However, when viability data is normalised to volume throughput, only a small improvement in cell inactivation is observed for silver nanoparticle coated sands relative to iron oxide coating alone. This counterintuitive result underscores the importance of net surface charge in controlling cell transport and inactivation and implies that the extra cost for implementing silver nanoparticle coatings on porous beds coated with iron oxides may not be justified in designing point of use water filters in low income countries.

  18. TonB Energy Transduction Systems of Riemerella anatipestifer Are Required for Iron and Hemin Utilization

    PubMed Central

    Liao, HeBin; Cheng, XingJun; Zhu, DeKang; Wang, MingShu; Jia, RenYong; Chen, Shun; Chen, XiaoYue; Biville, Francis; Liu, MaFeng; Cheng, AnChun

    2015-01-01

    Riemerella anatipestifer (R. anatipestifer) is one of the most important pathogens in ducks. The bacteria causes acute or chronic septicemia characterized by fibrinous pericarditis and meningitis. The R. anatipestifer genome encodes multiple iron/hemin-uptake systems that facilitate adaptation to iron-limited host environments. These systems include several TonB-dependent transporters and three TonB proteins responsible for energy transduction. These three tonB genes are present in all the R. anatipestifer genomes sequenced so far. Two of these genes are contained within the exbB-exbD-tonB1 and exbB-exbD-exbD-tonB2 operons. The third, tonB3, forms a monocistronic transcription unit. The inability to recover derivatives deleted for this gene suggests its product is essential for R. anatipestifer growth. Here, we show that deletion of tonB1 had no effect on hemin uptake of R. anatipestifer, though disruption of tonB2 strongly decreases hemin uptake, and disruption of both tonB1 and tonB2 abolishes the transport of exogenously added hemin. The ability of R. anatipestifer to grow on iron-depleted medium is decreased by tonB2 but not tonB1 disruption. When expressed in an E. coli model strain, the TonB1 complex, TonB2 complex, and TonB3 protein from R. anatipestifer cannot energize heterologous hemin transporters. Further, only the TonB1 complex can energize a R. anatipestifer hemin transporter when co-expressed in an E. coli model strain. PMID:26017672

  19. A new analytical approach to understanding nanoscale lead-iron interactions in drinking water distribution systems.

    PubMed

    Trueman, Benjamin F; Gagnon, Graham A

    2016-07-01

    High levels of iron in distributed drinking water often accompany elevated lead release from lead service lines and other plumbing. Lead-iron interactions in drinking water distribution systems are hypothesized to be the result of adsorption and transport of lead by iron oxide particles. This mechanism was explored using point-of-use drinking water samples characterized by size exclusion chromatography with UV and multi-element (ICP-MS) detection. In separations on two different stationary phases, high apparent molecular weight (>669 kDa) elution profiles for (56)Fe and (208)Pb were strongly correlated (average R(2)=0.96, N=73 samples representing 23 single-unit residences). Moreover, (56)Fe and (208)Pb peak areas exhibited an apparent linear dependence (R(2)=0.82), consistent with mobilization of lead via adsorption to colloidal particles rich in iron. A UV254 absorbance peak, coincident with high molecular weight (56)Fe and (208)Pb, implied that natural organic matter was interacting with the hypothesized colloidal species. High molecular weight UV254 peak areas were correlated with both (56)Fe and (208)Pb peak areas (R(2)=0.87 and 0.58, respectively). On average, 45% (std. dev. 10%) of total lead occurred in the size range 0.05-0.45 μm.

  20. Transport of zero-valent iron nanoparticles in carbonate-rich porous aquifers

    NASA Astrophysics Data System (ADS)

    Laumann, S.; Micic, V.; Hofmann, T.

    2012-04-01

    Use of nanoscale zero-valent iron (nZVI) for in situ dechlorination of chlorinated solvents in groundwater is a promising remediation technology, due to a high dechlorination efficiency of nZVI and possible applications in e.g., great depth or under above-ground infrastructure. The success of the in situ nZVI dechlorination strongly depends on the particle delivery to the contaminants. Previous studies reported a limited transport of nZVI through porous media (cm- to dm-range) and this has been recognized as one of the major obstacles in a widespread utilization of this technology (TRATNYEK & JOHNSON, 2006). Factors that limit the transport are particle aggregation and deposition onto the aquifer solids. Both depend on particle properties (e.g., size, shape, iron content, surface coating, surface charge), on concentrations of suspensions, and on site-specific parameters, such as the groundwater chemistry and the properties and inhomogeneity of the aquifer material. Adsorbed anionic polyelectrolyte coatings provide electrostatic double layer repulsions between negatively charged nZVI particles (SALEH ET AL., 2007), hindering their aggregation and also deposition on the negatively charged quartz surfaces (usually prevailing in aquifers). However, it is shown that the presence of surface charge heterogeneities in the aquifer effects the particle transport (JOHNSON ET AL., 1996). Carbonates, iron oxides, and the edges of clay minerals, for instance, carry a positive surface charge at neutral pH (often encountered in groundwater). This leads to a favorable deposition of negatively charged nZVI particles onto carbonates, metal oxide impurities or clay edges, and finally to a decreased particle transport. Considering the high proportion of carbonates commonly encountered in Alpine porous aquifers, in this study we aimed to evaluate the transport of commercially available polyelectrolyte coated nZVI (polyacrylic acid coated-nZVI, NANOIRON s.r.o., CZ) in both quartz and

  1. Overlap of copper and iron uptake systems in mitochondria in Saccharomyces cerevisiae.

    PubMed

    Vest, Katherine E; Wang, Jing; Gammon, Micah G; Maynard, Margaret K; White, Olivia L; Cobine, Jai A; Mahone, Wilkerson K; Cobine, Paul A

    2016-01-01

    In Saccharomyces cerevisiae, the mitochondrial carrier family protein Pic2 imports copper into the matrix. Deletion of PIC2 causes defects in mitochondrial copper uptake and copper-dependent growth phenotypes owing to decreased cytochrome c oxidase activity. However, copper import is not completely eliminated in this mutant, so alternative transport systems must exist. Deletion of MRS3, a component of the iron import machinery, also causes a copper-dependent growth defect on non-fermentable carbon. Deletion of both PIC2 and MRS3 led to a more severe respiratory growth defect than either individual mutant. In addition, MRS3 expressed from a high copy number vector was able to suppress the oxygen consumption and copper uptake defects of a strain lacking PIC2. When expressed in Lactococcus lactis, Mrs3 mediated copper and iron import. Finally, a PIC2 and MRS3 double mutant prevented the copper-dependent activation of a heterologously expressed copper sensor in the mitochondrial intermembrane space. Taken together, these data support a role for the iron transporter Mrs3 in copper import into the mitochondrial matrix.

  2. Overlap of copper and iron uptake systems in mitochondria in Saccharomyces cerevisiae

    PubMed Central

    Wang, Jing; Gammon, Micah G.; Maynard, Margaret K.; White, Olivia L.; Cobine, Jai A.; Mahone, Wilkerson K.

    2016-01-01

    In Saccharomyces cerevisiae, the mitochondrial carrier family protein Pic2 imports copper into the matrix. Deletion of PIC2 causes defects in mitochondrial copper uptake and copper-dependent growth phenotypes owing to decreased cytochrome c oxidase activity. However, copper import is not completely eliminated in this mutant, so alternative transport systems must exist. Deletion of MRS3, a component of the iron import machinery, also causes a copper-dependent growth defect on non-fermentable carbon. Deletion of both PIC2 and MRS3 led to a more severe respiratory growth defect than either individual mutant. In addition, MRS3 expressed from a high copy number vector was able to suppress the oxygen consumption and copper uptake defects of a strain lacking PIC2. When expressed in Lactococcus lactis, Mrs3 mediated copper and iron import. Finally, a PIC2 and MRS3 double mutant prevented the copper-dependent activation of a heterologously expressed copper sensor in the mitochondrial intermembrane space. Taken together, these data support a role for the iron transporter Mrs3 in copper import into the mitochondrial matrix. PMID:26763345

  3. Expression of the two mRNA isoforms of the iron transporter Nramp2/DMTI in mice and function of the iron responsive element.

    PubMed Central

    Tchernitchko, Dimitri; Bourgeois, Monique; Martin, Marie-Elise; Beaumont, Carole

    2002-01-01

    Nramp2/DMT1 is a transmembrane proton-coupled Fe(2+) transporter. Two different mRNAs are generated by alternative splicing; isoform I contains an iron responsive element (IRE), whereas isoform II does not. They encode two proteins differing at their C-terminal end and by their subcellular localization. IRE-mediated stabilization of isoform I mRNA is thought to stimulate DMT1 expression in response to iron deficiency. We have measured the two mRNAs by real-time quantitative PCR in several mouse tissues, in normal conditions or following injection of phenylhydrazine, a potent haemolytic agent. Isoform I mRNA is expressed in the duodenum and is induced by stimulation of erythropoiesis, whereas the non-IRE isoform is mostly induced in erythropoietic spleen. Surprisingly, both isoforms are highly expressed in the kidney and are not regulated by erythropoiesis. To evaluate the role of the IRE in regulating isoform I mRNA stability, in response to variations in cell iron status, several constructs were made in pCDNA3 with either a normal or a mutated IRE placed at the 3' end of a stable mRNA. These constructs were transfected into HT29 cells and mRNAs were analysed after growing cells in the presence or absence of exogenous iron. There was no difference in the level of expression of the different messages, suggesting that the IRE does not regulate stability of isoform I mRNA. The half-life of the endogenous IRE-mRNA was also measured following actinomycin D addition in iron- or desferrioxamine-treated cells. Decay of the mRNA was very similar in both conditions. These results suggest that additional transcriptional regulations at the promoter level, or iron-dependent regulation of alternative splicing are likely to participate in the induction of isoform I mRNA by iron deficiency. PMID:11964145

  4. Dictyostelium Nramp1, which is structurally and functionally similar to mammalian DMT1 transporter, mediates phagosomal iron efflux

    PubMed Central

    Buracco, Simona; Peracino, Barbara; Cinquetti, Raffaella; Signoretto, Elena; Vollero, Alessandra; Imperiali, Francesca; Castagna, Michela; Bossi, Elena; Bozzaro, Salvatore

    2015-01-01

    ABSTRACT The Nramp (Slc11) protein family is widespread in bacteria and eukaryotes, and mediates transport of divalent metals across cellular membranes. The social amoeba Dictyostelium discoideum has two Nramp proteins. Nramp1, like its mammalian ortholog (SLC11A1), is recruited to phagosomal and macropinosomal membranes, and confers resistance to pathogenic bacteria. Nramp2 is located exclusively in the contractile vacuole membrane and controls, synergistically with Nramp1, iron homeostasis. It has long been debated whether mammalian Nramp1 mediates iron import or export from phagosomes. By selectively loading the iron-chelating fluorochrome calcein in macropinosomes, we show that Dictyostelium Nramp1 mediates iron efflux from macropinosomes in vivo. To gain insight in ion selectivity and the transport mechanism, the proteins were expressed in Xenopus oocytes. Using a novel assay with calcein, and electrophysiological and radiochemical assays, we show that Nramp1, similar to rat DMT1 (also known as SLC11A2), transports Fe2+ and manganese, not Fe3+ or copper. Metal ion transport is electrogenic and proton dependent. By contrast, Nramp2 transports only Fe2+ in a non-electrogenic and proton-independent way. These differences reflect evolutionary divergence of the prototypical Nramp2 protein sequence compared to the archetypical Nramp1 and DMT1 proteins. PMID:26208637

  5. STARS: The Space Transportation Architecture Risk System

    NASA Technical Reports Server (NTRS)

    Greenberg, Joel S.

    1997-01-01

    Because of the need to perform comparisons between transportation systems that are likely to have significantly different levels of risk, both because of differing degrees of freedom in achieving desired performance levels and their different states of development and utilization, an approach has been developed for performing early comparisons of transportation architectures explicitly taking into account quantitative measures of uncertainty and resulting risk. The approach considers the uncertainty associated with the achievement of technology goals, the effect that the achieved level of technology will have on transportation system performance and the relationship between transportation system performance/capability and the ability to accommodate variations in payload mass. The consequences of system performance are developed in terms of expected values and associated standard deviations of nonrecurring, recurring and the present value of transportation system life cycle cost. Typical results are presented to illustrate the application of the methodology.

  6. Extracting archaeal populations from iron oxidizing systems

    NASA Astrophysics Data System (ADS)

    Whitmore, L. M.; Hutchison, J.; Chrisler, W.; Jay, Z.; Moran, J.; Inskeep, W.; Kreuzer, H.

    2013-12-01

    Unique environments in Yellowstone National Park offer exceptional conditions for studying microorganisms in extreme and constrained systems. However, samples from some extreme systems often contain inorganic components that pose complications during microbial and molecular analysis. Several archaeal species are found in acidic, geothermal ferric-oxyhydroxide mats; these species have been shown to adhere to mineral surfaces in flocculated colonies. For optimal microbial analysis, (microscopy, flow cytometry, genomic extractions, proteomic analysis, stable isotope analysis, and others), improved techniques are needed to better facilitate cell detachment and separation from mineral surfaces. As a requirement, these techniques must preserve cell structure while simultaneously minimizing organic carryover to downstream analysis. Several methods have been developed for removing sediments from mixed prokaryotic populations, including ultra-centrifugation, nycodenz gradient, sucrose cushions, and cell straining. In this study we conduct a comparative analysis of mechanisms used to detach archaeal cell populations from the mineral interface. Specifically, we evaluated mechanical and chemical approaches for cell separation and homogenization. Methods were compared using confocal microscopy, flow cytometry analyses, and real-time PCR detection. The methodology and approaches identified will be used to optimize biomass collection from environmental specimens or isolates grown with solid phases.

  7. Hexavalent chromium reduction with scrap iron in continuous-flow system. Part 2: Effect of scrap iron shape and size.

    PubMed

    Gheju, M; Balcu, I

    2010-10-15

    Hexavalent chromium reduction with scrap iron has the advantage that two wastes are treated simultaneously. The reduction of hexavalent chromium by scrap iron was investigated in continuous system, using as reducing agent the following scrap iron shapes and sizes: (1) spiral fibers, (2) shavings, and (3) powder. The shape and size of scrap iron were found to have a significant influence on chromium and iron species concentration in column effluent, on column effluent pH and on Cr(VI) reduction mechanism. While for large scrap iron particles (spiral fibers) homogeneous reduction is the dominant Cr(VI) reduction process, for small scrap iron particles (powder) heterogeneous reduction appears to be the dominant reaction contributing to Cr(VI) reduction. All three shapes and sizes investigated in this work have both advantages and disadvantages. If found in sufficient quantities, scrap iron powder seem to be the optimum shape and size for the continuous reduction of Cr(VI), due to the following advantages: (1) the greatest reduction capacity, (2) the most important pH increase in column effluent (up to 6.3), (3) no chromium was detected in the column effluent during the first 60 h of the experiment, and (4) the lowest steady-state Cr(VI) concentration observed in column effluent (3.7 mg/L). But, despite of a lower reduction capacity in comparison with powder particles, spiral fibers and shavings have the advantage to result in large quantities from the mechanic processing of steel.

  8. Molecular and Evolutionary Analysis of NEAr-Iron Transporter (NEAT) Domains

    PubMed Central

    Honsa, Erin S.; Maresso, Anthony W.; Highlander, Sarah K.

    2014-01-01

    Iron is essential for bacterial survival, being required for numerous biological processes. NEAr-iron Transporter (NEAT) domains have been studied in pathogenic Gram-positive bacteria to understand how their proteins obtain heme as an iron source during infection. While a 2002 study initially discovered and annotated the NEAT domain encoded by the genomes of several Gram-positive bacteria, there remains a scarcity of information regarding the conservation and distribution of NEAT domains throughout the bacterial kingdom, and whether these domains are restricted to pathogenic bacteria. This study aims to expand upon initial bioinformatics analysis of predicted NEAT domains, by exploring their evolution and conserved function. This information was used to identify new candidate domains in both pathogenic and nonpathogenic organisms. We also searched metagenomic datasets, specifically sequence from the Human Microbiome Project. Here, we report a comprehensive phylogenetic analysis of 343 NEAT domains, encoded by Gram-positive bacteria, mostly within the phylum Firmicutes, with the exception of Eggerthella sp. (Actinobacteria) and an unclassified Mollicutes bacterium (Tenericutes). No new NEAT sequences were identified in the HMP dataset. We detected specific groups of NEAT domains based on phylogeny of protein sequences, including a cluster of novel clostridial NEAT domains. We also identified environmental and soil organisms that encode putative NEAT proteins. Biochemical analysis of heme binding by a NEAT domain from a protein encoded by the soil-dwelling organism Paenibacillus polymyxa demonstrated that the domain is homologous in function to NEAT domains encoded by pathogenic bacteria. Together, this study provides the first global bioinformatics analysis and phylogenetic evidence that NEAT domains have a strong conservation of function, despite group-specific differences at the amino acid level. These findings will provide information useful for future projects

  9. High P-T diffusive transport properties of liquid iron alloys and peridotite melt

    NASA Astrophysics Data System (ADS)

    Posner, E. S.; Rubie, D. C.; Frost, D. J.; Vlček, V.; Steinle-Neumann, G.

    2015-12-01

    Diffusive transport properties of peridotite melt and molten iron alloys at high pressures and temperatures are important for understanding large-scale geodynamic processes and thermochemical evolution of planetary interiors, such as the time and length scales of metal-silicate equilibration during core formation and chemical exchange across core-mantle boundaries during cooling. In order to determine the pressure and temperature dependence of diffusion in these geologically relevant liquids, we have conducted experiments of Si, O, and Cr diffusion in liquid iron over the P-T range of 1.5—18 GPa and 1850—2450 K, and Si, O, Mg, Ca tracer and Ni, Co chemical diffusion in peridotite liquids over the P-T range of 4—24 GPa and 2248—2623 K in a multi-anvil apparatus. Our results show a very small pressure dependence (< 1 cm3/mol) of alloying element diffusion (Si, O, Cr) in liquid iron over the P-T range of the study and remarkably good consistency with first principles calculations (Pozzo et al. 2013. Phys. Rev. B 87, 014110; Ichikawa and Tsuchiya. 2015. Phys. Earth Planet. Inter., in press) when extrapolated to outer core conditions. Diffusion rates of Si, O, Ca, Mg, Ni, Co in silicate melt decrease with increasing pressure to a minimum at approximately 10 GPa. An anomalous pressure effect is observed above ~10 GPa such that diffusivities rapidly increase with increasing pressure for all elements to a maximum at ~12 GPa, consistent with previous work on peridotite viscosity to 13 GPa (Liebske et al. 2005. Earth Planet. Sci. Lett. 240, 589). Above ~12 GPa, diffusivities decrease with increasing pressure to 24 GPa. Peridotite melt viscosities calculated using the Eyring relation, oxygen self-diffusion rates, and average jump distance (λ) of 5.4 nm yield ~0.01 Pa s at 24 GPa and 2423 - 2623 K.

  10. The barium iron ruthenium oxide system

    NASA Technical Reports Server (NTRS)

    Kemmler-Sack, S.; Ehmann, A.

    1986-01-01

    In the system BaFe(1-x)Ru(x)O(3-y), three phases, separated by immiscibility gaps, are present: an Fe-rich phase (x = 0 to 0.75) with hexagonal BaTiO3 structure (6H; sequence (hcc)2), a Ru-rich phase (x = 0.9) of hexagonal 4H-type (sequence (hc)2), and the pure Ru compounds BaRuO3 with rhombohedral 9R structure (sequence (hhc)3). By vibrational spectroscopic investigations in the 6H phase a transition from n-type semiconduction (Fe-rich compounds with complete O lattice) can be detected. The 4H and 9R stacking polytypes are good, metal-like conductors. The lattice parameters are given.

  11. Transportation of volatile elements in thermally evolving planetesimals: An important role of metallic iron

    NASA Technical Reports Server (NTRS)

    Hashizume, K.; Sugiura, N.

    1994-01-01

    Ordinary chondrites are considered to have experienced thermal metamorphism in small bodies. We are interested in behaviors of volatile elements in such a kind of thermally evolving planetesimals. Volatile elements generally have high vapor pressures at high temperature. In porous bodies, with a high gas permeability, volatile elements are transported efficiently over a long range. Behavior of volatile elements transported by permeable gas flow can be handled by an equation whose form is similar to that of the equation of thermal diffusion. We can follow transportation of heats and volatile elements in planetesimals, when parameters in these equations, initial conditions and chemical behavior of volatile elements are given. Recently, we discovered that nitrogen in equilibrated H-chondrites is mainly trapped in taenite (f.c.c. Fe-Ni), probably dissolved in interstitial sites. Fegley suggests that metallic iron cannot trap nitrogen in the solar nebula gas due to its very low nitrogen partial pressure. Approximately 1 bar of nitrogen pressure is required to explain the nitrogen content in taenite. We may expect high nitrogen gas partial pressure (possibly produced by vaporization of nitrogen-bearing solids such as organic materials) at the interior of thermally evolving planetesimals. Kinetic behavior of nitrogen in taenite suggests that it can easily be equilibrated with the ambient nitrogen gas at temperatures of approximately 500 C or higher. We consider that nitrogen is trapped in taenite through a nitrogen redistribution process occurred during the thermal metamorphic event.

  12. The Newcastle geothermal system, Iron County, Utah

    SciTech Connect

    Blackett, R.E.; Shubat, M.A.; Bishop, C.E. ); Chapman, D.S.; Forster, C.B.; Schlinger, C.M. . Dept. of Geology and Geophysics)

    1990-03-01

    Geological, geophysical and geochemical studies contributed to conceptual hydrologic model of the blind'' (no surface expression), moderate-temperature (greater than 130{degree}C) Newcastle geothermal system, located in the Basin and Range-Colorado Plateau transition zone of southwestern Utah. Temperature gradient measurements define a thermal anomaly centered near the surface trace of the range-bounding Antelope Range fault with and elongate dissipative plume extending north into the adjacent Escalante Valley. Spontaneous potential and resistivity surveys sharply define the geometry of the dominant upflow zone (not yet explored), indicating that most of the thermal fluid issues form a short segment along the Antelope Range fault and discharges into a gently-dipping aquifer. Production wells show that this aquifer lies at a depth between 85 and 95 meter. Electrical surveys also show that some leakage of thermal fluid occurs over a 1.5 km (minimum) interval along the trace of the Antelope Range fault. Major element, oxygen and hydrogen isotopic analyses of water samples indicate that the thermal fluid is a mixture of meteoric water derived from recharge areas in the Pine Valley Mountains and cold, shallow groundwater. A northwest-southeast trending system of faults, encompassing a zone of increased fracture permeability, collects meteoric water from the recharge area, allows circulation to a depth of 3 to 5 kilometers, and intersects the northeast-striking Antelope Range fault. We postulate that mineral precipitates form a seal along the Antelope Range fault, preventing the discharge of thermal fluids into basin-fill sediments at depth, and allowing heated fluid to approach the surface. Eventually, continued mineral deposition could result in the development of hot springs at the ground surface.

  13. Low temperature charge transport and microwave absorption of carbon coated iron nanoparticles–polymer composite films

    SciTech Connect

    Prasad, V.

    2012-06-15

    Highlights: ► Carbon coated Fe nanoparticle–PVC composite films were prepared by solution casting method. ► A low electrical percolation threshold of 2.2 was achieved. ► The low temperature electrical conductivity follows variable range hopping type conduction. ► An EMI shielding of 18 dB was achieved in 200 micron thick film. -- Abstract: In this paper, the low temperature electrical conductivity and microwave absorption properties of carbon coated iron nanoparticles–polyvinyl chloride composite films are investigated for different filler fractions. The filler particles are prepared by the pyrolysis of ferrocene at 980 °C and embedded in polyvinyl chloride matrix. The high resolution transmission electron micrographs of the filler material have shown a 5 nm thin layer graphitic carbon covering over iron particles. The room temperature electrical conductivity of the composite film changes by 10 orders of magnitude with the increase of filler concentration. A percolation threshold of 2.2 and an electromagnetic interference shielding efficiency (EMI SE) of ∼18.6 dB in 26.5–40 GHz range are observed for 50 wt% loading. The charge transport follows three dimensional variable range hopping conduction.

  14. Competitive adsorption, displacement, and transport of organic matter on iron oxide: I. Competitive adsorption

    NASA Astrophysics Data System (ADS)

    Gu, Baohua; Mehlhorn, Tonia L.; Liang, Liyuan; McCarthy, John F.

    1996-06-01

    Different organic compounds or fractions of natural organic matter (NOM) show different adsorption affinities ( K) and capacities ( qm) on mineral surfaces. We hypothesize that these different organic compounds or fractions compete for adsorption when surface adsorption sites are limited. In this study, competitive adsorption of binary mixtures of Suwannee River NOM (SR-NOM), polyacrylic acid (PAA), phthalic acid, and salicylic acid on iron oxide was investigated at a constant solid:solution ratio, temperature, and pressure, but at varying C weight fractions, pH, and solution concentrations of the mixture. Results revealed that, in general, PAA is the most competitive whereas SR-NOM is more competitive than phthalic and salicylic acids. The competitive adsorption of these organic compounds is pH-dependent. At pH < 4, PAA becomes less competitive than SR-NOM or phthalic and salicylic acids. The competition among these organic compounds may be related to their carboxyl functional groups and their molecular structure. The overall strong competitiveness of PAA at pH > 4 in comparison with other organics is attributed to its high carboxyl density and linear molecular structure, which promote strong surface complexation with iron oxide. Because of the heterogeneity or polydispersity of NOM, this research indicates that NOM partitioning and transport in the subsurface soil environment are influenced by the dynamic competitive interactions between NOM subcomponents (or fractions). This process ultimately influences the distribution, interaction, and cotransport of contaminants and mineral colloids that are associated with NOM.

  15. Effects of symmetry and spin configuration on spin-dependent transport properties of iron-phthalocyanine-based devices

    SciTech Connect

    Cui, Li-Ling; Yang, Bing-Chu Li, Xin-Mei; Cao, Can; Long, Meng-Qiu

    2014-07-21

    Spin-dependent transport properties of nanodevices constructed by iron-phthalocyanine (FePc) molecule sandwiched between two zigzag graphene nanoribbon electrodes are studied using first-principles quantum transport calculations. The effects of the symmetry and spin configuration of electrodes have been taken into account. It is found that large magnetoresistance, large spin polarization, dual spin-filtering, and negative differential resistance (NDR) can coexist in these devices. Our results show that 5Z-FePc system presents well conductive ability in both parallel (P) and anti-parallel (AP) configurations. For 6Z-FePc-P system, spin filtering effect and large spin polarization can be found. A dual spin filtering and NDR can also be shown in 6Z-FePc-AP. Our studies indicate that the dual spin filtering effect depends on the orbitals symmetry of the energy bands and spin mismatching of the electrodes. And all the effects would open up possibilities for their applications in spin-valve, spin-filter as well as effective spin diode devices.

  16. Effects of symmetry and spin configuration on spin-dependent transport properties of iron-phthalocyanine-based devices

    NASA Astrophysics Data System (ADS)

    Cui, Li-Ling; Yang, Bing-Chu; Li, Xin-Mei; Cao, Can; Long, Meng-Qiu

    2014-07-01

    Spin-dependent transport properties of nanodevices constructed by iron-phthalocyanine (FePc) molecule sandwiched between two zigzag graphene nanoribbon electrodes are studied using first-principles quantum transport calculations. The effects of the symmetry and spin configuration of electrodes have been taken into account. It is found that large magnetoresistance, large spin polarization, dual spin-filtering, and negative differential resistance (NDR) can coexist in these devices. Our results show that 5Z-FePc system presents well conductive ability in both parallel (P) and anti-parallel (AP) configurations. For 6Z-FePc-P system, spin filtering effect and large spin polarization can be found. A dual spin filtering and NDR can also be shown in 6Z-FePc-AP. Our studies indicate that the dual spin filtering effect depends on the orbitals symmetry of the energy bands and spin mismatching of the electrodes. And all the effects would open up possibilities for their applications in spin-valve, spin-filter as well as effective spin diode devices.

  17. The transportation operations system: A description

    SciTech Connect

    Best, R.E.; Danese, F.L.; Dixon, L.D.; Peterson, R.W. ); Pope, R.B. )

    1990-01-01

    This paper presents a description of the system for transporting radioactive waste that may be deployed to accomplish the assigned system mission, which includes accepting spent nuclear fuel (SNF) and high-level radioactive waste (HLW) from waste generator sites and transporting them to the FWMS destination facilities. The system description presented here contains, in part, irradiated fuel and waste casks, ancillary equipments, truck, rail, and barge transporters, cask and vehicle traffic management organizations, maintenance facilities, and other operations elements. The description is for a fully implemented system, which is not expected to be achieved, however, until several years after initial operations. 6 figs.

  18. Siderophore-mediated iron acquisition systems in Bacillus cereus: identification of receptors for anthrax virulence-associated petrobactin†a

    PubMed Central

    Zawadzka, Anna M.; Abergel, Rebecca J.; Nichiporuk, Rita; Andersen, Ulla N.; Raymond, Kenneth N.

    2009-01-01

    During growth under iron limitation, Bacillus cereus and Bacillus anthracis, two human pathogens from the Bacillus cereus group of Gram-positive bacteria, secrete two siderophores, bacillibactin (BB) and petrobactin (PB), for iron acquisition via membrane-associated substrate-binding proteins (SBPs) and other ABC transporter components. Since PB is associated with virulence traits in B. anthracis, the PB-mediated iron uptake system presents a potential target for antimicrobial therapies; its characterization in B. cereus is described here. Separate transporters for BB, PB, and several xenosiderophores are suggested by 55Fe-siderophore uptake studies. The PB precursor, 3,4-dihydroxybenzoic acid (3,4-DHB), and the photoproduct of FePB (FePBν) also mediate iron delivery into iron-deprived cells. Putative SBPs were recombinantly expressed, and their ligand specificity and binding affinity assessed using fluorescence spectroscopy. The noncovalent complexes of the SBPs with their respective siderophores were characterized using ESI-MS. The differences between solution phase behavior and gas phase measurements are indicative of noncovalent interactions between the siderophores and the binding sites of their respective SBPs. These studies combined with bioinformatics sequence comparison identify SBPs from five putative transporters specific for BB and enterobactin (FeuA), 3,4-DHB and PB (FatB), PB (FpuA), schizokinen (YfiY), and desferrioxamine and ferrichrome (YxeB). The two PB receptors show different substrate ranges: FatB has the highest affinity for ferric 3,4-DHB, iron-free PB, FePB, and FePBν, whereas FpuA is specific to only apo- and ferric PB. The biochemical characterization of these SBPs provides the first identification of the transporter candidates that most likely play a role in the B. cereus group pathogenicity. PMID:19254027

  19. Siderophore-mediated iron acquisition systems in Bacillus cereus: Identification of receptors for anthrax virulence-associated petrobactin .

    PubMed

    Zawadzka, Anna M; Abergel, Rebecca J; Nichiporuk, Rita; Andersen, Ulla N; Raymond, Kenneth N

    2009-04-28

    During growth under iron limitation, Bacillus cereus and Bacillus anthracis, two human pathogens from the Bacillus cereus group of Gram-positive bacteria, secrete two siderophores, bacillibactin (BB) and petrobactin (PB), for iron acquisition via membrane-associated substrate-binding proteins (SBPs) and other ABC transporter components. Since PB is associated with virulence traits in B. anthracis, the PB-mediated iron uptake system presents a potential target for antimicrobial therapies; its characterization in B. cereus is described here. Separate transporters for BB, PB, and several xenosiderophores are suggested by (55)Fe-siderophore uptake studies. The PB precursor, 3,4-dihydroxybenzoic acid (3,4-DHB), and the photoproduct of FePB (FePB(nu)) also mediate iron delivery into iron-deprived cells. Putative SBPs were recombinantly expressed, and their ligand specificity and binding affinity were assessed using fluorescence spectroscopy. The noncovalent complexes of the SBPs with their respective siderophores were characterized using ESI-MS. The differences between solution phase behavior and gas phase measurements are indicative of noncovalent interactions between the siderophores and the binding sites of their respective SBPs. These studies combined with bioinformatics sequence comparison identify SBPs from five putative transporters specific for BB and enterobactin (FeuA), 3,4-DHB and PB (FatB), PB (FpuA), schizokinen (YfiY), and desferrioxamine and ferrichrome (YxeB). The two PB receptors show different substrate ranges: FatB has the highest affinity for ferric 3,4-DHB, iron-free PB, FePB, and FePB(nu), whereas FpuA is specific to only apo- and ferric PB. The biochemical characterization of these SBPs provides the first identification of the transporter candidates that most likely play a role in the B. cereus group pathogenicity.

  20. Systems Studies of DDT Transport

    ERIC Educational Resources Information Center

    Harrison, H. L.; And Others

    1970-01-01

    Major consequences of present and additional environmental quantities of DDT pesticide are predictable by mathematical models of transport, accumulation and concentration mechanisms in the Wisconsin regional ecosystem. High solubility and stability produce increased DDT concentrations at high organism trophic levels within world biosphere…

  1. In Situ Probing Nucleation, Growth, and Aggregation of Iron Oxides in Geochemical Aquatic Systems

    NASA Astrophysics Data System (ADS)

    Jun, Y.; Hu, Y.; Ray, J. R.

    2012-12-01

    dominant mechanism during in situ nanoparticle formation, among process such as nucleation, growth, Ostwald ripening, and aggregation. These results address critical deficits in our understanding of the complex and dynamic nature of surface coatings of iron oxide nanoparticles in geochemical aquatic systems. They will also help connect the gaps between empirical and molecular scale modeling approaches at the nanoscale and further help design a more rigorous reactive transport model to predict the fate and transport of contaminants in mesoscale approaches.

  2. The molecular mechanisms of the metabolism and transport of iron in normal and neoplastic cells.

    PubMed

    Richardson, D R; Ponka, P

    1997-03-14

    Iron uptake by mammalian cells is mediated by the binding of serum Tf to the TfR. Transferrin is then internalized within an endocytotic vesicle by receptor-mediated endocytosis and the Fe released from the protein by a decrease in endosomal pH. Apart from this process, several cell types also have other efficient mechanisms of Fe uptake from Tf that includes a process consistent with non-specific adsorptive pinocytosis and a mechanism that is stimulated by small-Mr Fe complexes. This latter mechanism appears to be initiated by hydroxyl radicals generated by the Fe complexes, and may play a role in Fe overload disease where a significant amount of serum non-Tf-bound Fe exists. Apart from Tf-bound Fe uptake, mammalian cells also possess a number of mechanisms that can transport Fe from small-Mr Fe complexes into the cell. In fact, recent studies have demonstrated that the membrane-bound Tf homologue, MTf, can bind and internalize Fe from 59Fe-citrate. However, the significance of this Fe uptake process and its pathophysiological relevance remain uncertain. Iron derived from Tf or small-Mr complexes is probably transported into mammalian cells in the Fe(II) state. Once Fe passes through the membrane, it then becomes part of the poorly characterized intracellular labile Fe pool. Iron in the labile Fe pool that is not used for immediate requirements is stored within the Fe-storage protein, ferritin. Cellular Fe uptake and storage are coordinately regulated through a feedback control mechanism mediated at the post-transcriptional level by cytoplasmic factors known as IRP1 and IRP2. These proteins bind to stem-loop structures known as IREs on the 3 UTR of the TfR mRNA and 5 UTR of ferritin and erythroid delta-aminolevulinic acid synthase mRNAs. Interestingly, recent work has suggested that the short-lived messenger molecule, NO (or its by-product, peroxynitrite), can affect cellular Fe metabolism via its interaction with IRP1. Moreover, NO can decrease Fe uptake from Tf

  3. Brain capillary endothelium and choroid plexus epithelium regulate transport of transferrin-bound and free iron into the rat brain

    PubMed Central

    Deane, Rashid; Zheng, Wei; Zlokovic, Berislav V.

    2014-01-01

    Iron transport into the CNS is still not completely understood. Using a brain perfusion technique in rats, we have shown a significant brain capillary uptake of circulating transferrin (Tf)-bound and free 59Fe (1 nM) at rates of 136 ± 26 and 182 ± 23 μL/g/min, respectively, while their respective transport rates into brain parenchyma were 1.68 ± 0.56 and 1.52 ± 0.48 μL/g/min. Regional Tf receptor density (Bmax) in brain endothelium determined with 125I-holo-Tf correlated well with 59Fe-Tf regional brain uptake rates reflecting significant vascular association of iron. Tf-bound and free circulating 59Fe were sequestered by the choroid plexus and transported into the CSF at low rates of 0.17 ± 0.01 and 0.09 ± 0.02 μL/min/g, respectively, consistent with a 10-fold brain-CSF concentration gradient for 59Fe, Tf-bound or free. We conclude that transport of circulating Tf-bound and free iron could be equally important for its delivery to the CNS. Moreover, data suggest that entry of Tf-bound and free iron into the CNS is determined by (i) its initial sequestration by brain capillaries and choroid plexus, and (ii) subsequent controlled and slow release from vascular structures into brain interstitial fluid and CSF. PMID:14756801

  4. BACTERIOPHAGE PRD1 AND SILICA COLLOID TRANSPORT AND RECOVERY IN AN IRON OXIDE-COATED SAND AQUIFER. (R826179)

    EPA Science Inventory

    Bacteriophage PRD1 and silica colloids were co-injected into
    sewage-contaminated and uncontaminated zones of an iron oxide-coated sand
    aquifer on Cape Cod, MA, and their transport was monitored over distances up to
    6 m in three arrays. After deposition, the attache...

  5. Transportation Systems. Curriculum Guide for Technology Education.

    ERIC Educational Resources Information Center

    Chastain, Gary K.

    This curriculum guide for a 1-semester or 1-year course in transportation provides activities that show and explain many of the occupations, devices, and systems that are related to transportation on land, water, air, and space. The guide contains competencies (task lists), student competency records, and management sheets. Management sheets,…

  6. Structural interaction with transportation and handling systems

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Problems involved in the handling and transportation of finished space vehicles from the factory to the launch site are presented, in addition to recommendations for properly accounting for in space vehicle structural design, adverse interactions during transportation. Emphasis is given to the protection of vehicle structures against those environments and loads encountered during transportation (including temporary storage) which would exceed the levels that the vehicle can safely withstand. Current practices for verifying vehicle safety are appraised, and some of the capabilities and limitations of transportation and handling systems are summarized.

  7. System for recycling char in iron oxide reducing kilns

    SciTech Connect

    Baker, A.C.; Keran, V.P.

    1983-03-08

    A method and means for improving the efficiency of the process for directly reducing ore containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the charred coal or char found in the discharge product is recycled into the process at the discharge end of the kiln rather than the feed end as in the prior art. In particular, the recovered char, both coarse and finer particles, are transported to a recycle bin from which they are returned at a preselected rate to the kiln process by being injected along with the coal blown into the discharge end of the kiln. Alternatively, the recycle char alone may be fed without any coal at the discharge end of the kiln.

  8. Formation of the first oxidized iron in the solar system

    NASA Astrophysics Data System (ADS)

    Grossman, Lawrence; Fedkin, Alexei V.; Simon, Steven B.

    2012-12-01

    Abstract-For fayalite formation times of several thousand years, and <span class="hlt">systems</span> enriched in water by a factor of ten relative to solar composition, 1 μm radius olivine grains could reach 2 mole% fayalite and 0.1 μm grains 5 mole% by nebular condensation, well short of the values appropriate for precursors of most chondrules and the values found in the matrices of unequilibrated ordinary chondrites. Even 10 μm olivine crystals could reach 30 mole% fayalite above 1100 K in solar gas if condensation of metallic nickel-<span class="hlt">iron</span> were delayed sufficiently by supersaturation. Consideration of the surface tensions of several phases with equilibrium condensation temperatures above that of metallic <span class="hlt">iron</span> shows that, even if they were supersaturated, they would still nucleate homogeneously above the equilibrium condensation temperature of metallic <span class="hlt">iron</span>. This phenomenon would have provided nuclei for heterogeneous nucleation of metallic nickel-<span class="hlt">iron</span>, thus preventing the latter from supersaturating significantly and preventing olivine from becoming fayalitic. Unless a way is found to make nebular regions far more oxidizing than in existing models, it is unlikely that chondrule precursors or the matrix olivine grains of unequilibrated ordinary chondrites obtained their fayalite contents by condensation processes. Perhaps stabilization of FeO occurred after condensation of water ice and accretion of icy planetesimals, during heating of the planetesimals and/or in hot, dense, water-rich vapor plumes generated by impacts on them. This would imply that FeO is a relatively young feature of nebular materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3857035','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3857035"><span id="translatedtitle">The Pharmacokinetics and Pharmacodynamics of <span class="hlt">Iron</span> Preparations</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Geisser, Peter; Burckhardt, Susanna</p> <p>2011-01-01</p> <p>Standard approaches are not appropriate when assessing pharmacokinetics of <span class="hlt">iron</span> supplements due to the ubiquity of endogenous <span class="hlt">iron</span>, its compartmentalized sites of action, and the complexity of the <span class="hlt">iron</span> metabolism. The primary site of action of <span class="hlt">iron</span> is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3–4 weeks. Accordingly, serum <span class="hlt">iron</span> concentration and area under the curve (AUC) are clinically irrelevant for assessing <span class="hlt">iron</span> utilization. <span class="hlt">Iron</span> can be administered intravenously in the form of polynuclear <span class="hlt">iron</span>(III)-hydroxide complexes with carbohydrate ligands or orally as <span class="hlt">iron</span>(II) (ferrous) salts or <span class="hlt">iron</span>(III) (ferric) complexes. Several approaches have been employed to study the pharmacodynamics of <span class="hlt">iron</span> after oral administration. Quantification of <span class="hlt">iron</span> uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total <span class="hlt">iron</span> transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral <span class="hlt">iron</span> preparations are directly related to the molecular weight and the stability of the complex. High oral <span class="hlt">iron</span> doses or rapid release of <span class="hlt">iron</span> from intravenous <span class="hlt">iron</span> preparations can saturate the <span class="hlt">iron</span> <span class="hlt">transport</span> <span class="hlt">system</span>, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia. PMID:24310424</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17448519','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17448519"><span id="translatedtitle">Chromate <span class="hlt">transport</span> through columns packed with surfactant-modified zeolite/zero valent <span class="hlt">iron</span> pellets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Zhaohui; Kirk Jones, H; Zhang, Pengfei; Bowman, Robert S</p> <p>2007-08-01</p> <p>Chromate <span class="hlt">transport</span> through columns packed with zeolite/zero valent <span class="hlt">iron</span> (Z/ZVI) pellets, either untreated or treated with the cationic surfactant hexadecyltrimethylammonium (HDTMA), was studied at different flow rates. In the presence of sorbed HDTMA, the chromate retardation factor increased by a factor of five and the pseudo first-order rate constant for chromate reduction increased by 1.5-5 times. The increase in rate constant from the column studies was comparable to a six-fold increase in the rate constant determined in a batch study. At a fast flow rate, the apparent delay in chromate breakthrough from the HDTMA modified Z/ZVI columns was primarily caused by the increase in chromate reduction rate constant. In contrast, at a slower flow rate, the retardation in chromate <span class="hlt">transport</span> from the HDTMA modified Z/ZVI columns mainly originated from chromate sorption onto the HDTMA modified Z/ZVI pellets. Due to dual porosity, the presence of immobile water was responsible for the earlier breakthrough of chromate in columns packed with zeolite and Z/ZVI pellets. The results from this study further confirm the role of HDTMA in enhancing sorption and reduction efficiency of contaminants in groundwater remediation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25465754','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25465754"><span id="translatedtitle">Influence of silicate on the <span class="hlt">transport</span> of bacteria in quartz sand and <span class="hlt">iron</span> mineral-coated sand.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dong, Zhe; Yang, Haiyan; Wu, Dan; Ni, Jinren; Kim, Hyunjung; Tong, Meiping</p> <p>2014-11-01</p> <p>The influence of silicate on the <span class="hlt">transport</span> and deposition of bacteria (Escherichia coli) in packed porous media were examined at a constant 20 mM ionic strength with different silicate concentrations (from 0 to 1 mM) at pH 7. <span class="hlt">Transport</span> experiments were performed in two types of representative porous media, both bare quartz sand and <span class="hlt">iron</span> mineral-coated quartz sand. In bare quartz sand, the breakthrough plateaus in the presence of silicate in suspensions were lower and the corresponding retained profiles were higher than those without silicate ions, indicating that the presence of silicate in suspensions decreased cell <span class="hlt">transport</span> in bare quartz sand. Moreover, the decrease of bacteria <span class="hlt">transport</span> in quartz sand induced by silicate was more pronounced with increasing silicate concentrations from 0 to 1 mM. However, when EPS was removed from cell surfaces, the presence of silicate in cell suspensions (with different concentrations) did not affect the <span class="hlt">transport</span> behavior of bacteria in quartz sand. The interaction of silicate with EPS on cell surfaces negatively decreased the zeta potentials of bacteria, resulting in the decreased cell <span class="hlt">transport</span> in bare quartz sand when silicate was copresent in bacteria suspensions. In contrast, the presence of silicate in suspensions increased cell <span class="hlt">transport</span> in <span class="hlt">iron</span> mineral-coated sand. Silicate ions competed with bacteria for the adsorption sites on mineral-coated sand, contributing to the increased cell <span class="hlt">transport</span> in mineral-coated sand with silicate present in cell suspensions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3708341','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3708341"><span id="translatedtitle"><span class="hlt">Iron</span> Absorption in Drosophila melanogaster</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis</p> <p>2013-01-01</p> <p>The way in which Drosophila melanogaster acquires <span class="hlt">iron</span> from the diet remains poorly understood despite <span class="hlt">iron</span> absorption being of vital significance for larval growth. To describe the process of organismal <span class="hlt">iron</span> absorption, consideration needs to be given to cellular <span class="hlt">iron</span> import, storage, export and how intestinal epithelial cells sense and respond to <span class="hlt">iron</span> availability. Here we review studies on the Divalent Metal <span class="hlt">Transporter</span>-1 homolog Malvolio (<span class="hlt">iron</span> import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (<span class="hlt">iron</span> export) and the role of ferritin in the process of <span class="hlt">iron</span> acquisition (<span class="hlt">iron</span> storage). We also describe what is known about <span class="hlt">iron</span> regulation in insect cells. We then draw upon knowledge from mammalian <span class="hlt">iron</span> homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, <span class="hlt">systemic</span> <span class="hlt">iron</span> regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal <span class="hlt">iron</span> uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to <span class="hlt">iron</span> sequestration. PMID:23686013</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730007089','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730007089"><span id="translatedtitle">Propulsion <span class="hlt">system</span> for research VTOL <span class="hlt">transports</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gertsma, L. W.; Zigan, S.</p> <p>1973-01-01</p> <p>In anticipation of an eventual VTOL requirement for civil aviation, NASA has been conducting studies directed toward determining and developing the technology required for a commercial VTOL <span class="hlt">transport</span>. In this paper, the commercial <span class="hlt">transport</span> configurations are briefly reviewed; the propulsion <span class="hlt">system</span> specifications and components developed by the engine study contractor are presented and described; and methods for using the lift-propulsion <span class="hlt">system</span> for aircraft attitude control are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988spte....2.1515K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988spte....2.1515K"><span id="translatedtitle">The German Saenger space <span class="hlt">transportation</span> <span class="hlt">system</span> concept</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koelle, D. E.; Kuczera, H.; Hoegenauer, E.</p> <p></p> <p>The vehicle configuration, performance criteria, and technological problems of the Saenger space <span class="hlt">transportation</span> <span class="hlt">system</span> are reviewed. The vehicle consists of a two-stage <span class="hlt">system</span>, including a hypersonic first stage employing turboramjet propulsion. The cruise speed is Mach 4.4, with the capability to accelerate to Mach 6.8 prior to separation of the upper stage. Two different upper stages are proposed to fulfull the different requirements of manned space flight and unmanned payload <span class="hlt">transportation</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3062936','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3062936"><span id="translatedtitle">[Relation of <span class="hlt">iron</span> supply and <span class="hlt">iron</span> metabolism to infectious diseases and parasitoses and the competence of the immune <span class="hlt">system</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kolb, E</p> <p>1988-11-01</p> <p>In many infectious diseases and in several parasitoses the <span class="hlt">iron</span> content in the blood plasma occasionally decreases. By reduction of the saturation of the transferrins with <span class="hlt">iron</span> the bactericidal effect of the blood plasma is increased. In these cases the <span class="hlt">iron</span> absorption into the liver is increased and the <span class="hlt">iron</span> excretion from the reticulohistiocytic <span class="hlt">system</span> decreased. The oral intake of easily soluble <span class="hlt">iron</span> compounds which goes far beyond the need repeatedly an enteral increase of germs of Yersinia enterocolitica and a transition into the blood, respectively, was stated. The parenteral administration of Fe-dextran from time to time leads to an enrichment of this compound in macrophages, the performance of phagocytosis of which is thus restricted. The <span class="hlt">iron</span> deficiency decreases the functional capacity of the immune <span class="hlt">system</span>. The functional ability of the T- and B-lymphocytes as well as of the macrophages is reduced. The importance of the transferrins, of haemopexin, of haptoglobin and of lactoferrin for the defense of infections is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050160165','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050160165"><span id="translatedtitle"><span class="hlt">Systemic</span> Analysis Approaches for Air <span class="hlt">Transportation</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Conway, Sheila</p> <p>2005-01-01</p> <p>Air <span class="hlt">transportation</span> <span class="hlt">system</span> designers have had only limited success using traditional operations research and parametric modeling approaches in their analyses of innovations. They need a <span class="hlt">systemic</span> methodology for modeling of safety-critical infrastructure that is comprehensive, objective, and sufficiently concrete, yet simple enough to be used with reasonable investment. The methodology must also be amenable to quantitative analysis so issues of <span class="hlt">system</span> safety and stability can be rigorously addressed. However, air <span class="hlt">transportation</span> has proven itself an extensive, complex <span class="hlt">system</span> whose behavior is difficult to describe, no less predict. There is a wide range of <span class="hlt">system</span> analysis techniques available, but some are more appropriate for certain applications than others. Specifically in the area of complex <span class="hlt">system</span> analysis, the literature suggests that both agent-based models and network analysis techniques may be useful. This paper discusses the theoretical basis for each approach in these applications, and explores their historic and potential further use for air <span class="hlt">transportation</span> analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005AGUFM.B13A1044V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005AGUFM.B13A1044V&link_type=ABSTRACT"><span id="translatedtitle">Geomicrobiological Regeneration of <span class="hlt">Iron</span> Sulfides in Engineered barrier <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vannela, R.; Adriaens, P.; Hayes, K. F.</p> <p>2005-12-01</p> <p>The reactive capacity of <span class="hlt">iron</span> sulfide-based permeable reactive barriers (PRB) to complex and co-precipitate heavy metal ions from groundwater will depend on the potential for regeneration of reactive FeS during the expected lifetime of the PRB. FeS reactivity may decrease in a PRB in time as the result of the following processes: (i) oxidation of FeS and the formation of ferric <span class="hlt">iron</span> (Fe(III)) oxide solids in the presence of oxygenated groundwater at the entrance of the PRB, (ii) oxidation of FeS in the presence of redox active metals like As(V) with the formation of ferric solids, (iii) co-precipitation of heavy metals within the PRB with the reactive FeS leading to the formation of insoluble metal sulfides co-precipitates with the concomitant release of ferrous <span class="hlt">iron</span> and formation of ferrous (Fe(II) oxide, hydroxide, or carbonate solids, (iv) clogging of the PRB structure due to formation of precipitate products from processes (i) - (iii).. We have demonstrated the formation of triolite in the presence of an oxidized form of hydrous ferric oxide (HFO), various sulfate concentrations, and biomass densities for the sulfate reducing bacterium (SRB) Desulfovibrio vulgaris. This result has allowed us to demonstrate the feasibility of regeneration of FeS from the ferric oxide and hydroxide solids that may be produced under scenarios (i) and (ii) above as well as to establish the electron donor and acceptor requirements for this SRB. Using Desulfobacterium autotrophicum, both HFO and soluble complexed forms of ferric <span class="hlt">iron</span> gave rise to the formation of mackinawite. The latter have been shown to react with As (V) and Cd (II) to form ferric solids. Both organisms will be used to generate FeS solids in the presence of crystalline forms of ferric solids expected to form from scenarios (i) and (ii) (e.g., goethite and the mixed Fe(II)/(Fe(III) magnetite, and green rusts) and ferrous <span class="hlt">iron</span> solids from scenarios (iii) and (iv) (Fe(II) oxides and siderite). Similar to the study</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12076970','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12076970"><span id="translatedtitle">Nitric oxide <span class="hlt">transport</span> and storage in the cardiovascular <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Muller, Bernard; Kleschyov, Andrei L; Alencar, Jacicarlos L; Vanin, Anatoly; Stoclet, Jean-Claude</p> <p>2002-05-01</p> <p>Despite short halflife in biological fluids, nitric oxide (NO) can produce remote or long lasting effect in the cardiovascular <span class="hlt">system</span>. Long distance <span class="hlt">transport</span> or local storage of NO might explain these effects. In blood, recent findings suggest that in addition to being a major consumption pathway, interaction of NO with hemoglobin may permit O(2)-governed <span class="hlt">transport</span> of NO (as S-nitrosohemoglobin) to tissues in which NO may be released together with O(2), via transnitrosation of a <span class="hlt">transport</span> protein. In blood vessels, two different putative NO stores have been characterized. The first is the photosensitive store, formed from endothelium-derived NO. The mechanism of NO release from this store in the body (in absence of light) and its physiological relevance are unknown. The second store is generated in conditions of high tissue NO levels, as a consequence of the inducible NO synthase activity or in various stress conditions. This NO store involves formation of protein-bound dinitrosyl <span class="hlt">iron</span> complexes or S-nitrosated proteins, or both. Low molecular weight thiols can displace NO from these stores and probably transfer it to target membrane protein(s) such as K(+) channels, via transnitrosation reactions. These stores may be involved in defence mechanisms against inflammation or stress. Thus, NO <span class="hlt">transport</span> and storage mechanisms may be implicated in a variety of NO effects. The mechanisms of their formation and of NO release and their physiologic and pathophysiologic relevance deserve further investigations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10107012','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10107012"><span id="translatedtitle">The WIPP <span class="hlt">transportation</span> <span class="hlt">system</span>: Dedicated to safety</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ward, T.; McFadden, M.</p> <p>1993-12-01</p> <p>When developing a <span class="hlt">transportation</span> <span class="hlt">system</span> to <span class="hlt">transport</span> transuranic (TRU) waste from ten widely-dispersed generator sites, the Department of Energy (DOE) recognized and addressed many challenges. Shipments of waste to the Waste Isolation Pilot Plant (WIPP) were to cover a twenty-five year period and utilize routes covering over twelve thousand miles in twenty-three states. Enhancing public safety by maximizing the payload, thus reducing the number of shipments, was the primary objective. To preclude the requirement for overweight permits, the DOE started with a total shipment weight limit of 80,000 pounds and developed an integrated <span class="hlt">transportation</span> <span class="hlt">system</span> consisting of a Type ``B`` package to <span class="hlt">transport</span> the material, a lightweight tractor and trailer, stringent driver requirements, and a shipment tracking <span class="hlt">system</span> referred to as ``TRANSCOM``.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/3372473','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/3372473"><span id="translatedtitle"><span class="hlt">Systemic</span> virulence of Erwinia chrysanthemi 3937 requires a functional <span class="hlt">iron</span> assimilation <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Enard, C; Diolez, A; Expert, D</p> <p>1988-06-01</p> <p>In Erwinia chrysanthemi, conditions of <span class="hlt">iron</span> starvation initiate production of a catechol-type siderophore and enhance production of three outer membrane polypeptides. Twenty-two mutants affected in the different stages of this <span class="hlt">iron</span> assimilation <span class="hlt">system</span> were isolated by mini-Mu insertion mutagenesis. All of them failed to induce <span class="hlt">systemic</span> soft rot on axenically grown Saintpaulia plants. From the siderophore auxotrophs and the <span class="hlt">iron</span> uptake mutants, clones having recovered the missing function(s) were isolated by using the in vivo cloning vector pULB113 (RP4::mini-Mu). An R-prime plasmid containing a ca. 35.5-kilobase-pair DNA insert was identified. Restoration of the <span class="hlt">iron</span> functions restored partially, if not completely, the virulence of the parental strain. PMID:3372473</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EntIS...8..391W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EntIS...8..391W"><span id="translatedtitle">Automatic control <span class="hlt">system</span> for uniformly paving <span class="hlt">iron</span> ore pellets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Bowen; Qian, Xiaolong</p> <p>2014-05-01</p> <p>In <span class="hlt">iron</span> and steelmaking industry, <span class="hlt">iron</span> ore pellet qualities are crucial to end-product properties, manufacturing costs and waste emissions. Uniform pellet pavements on the grate machine are a fundamental prerequisite to ensure even heat-transfer and pellet induration successively influences performance of the following metallurgical processes. This article presents an automatic control <span class="hlt">system</span> for uniformly paving green pellets on the grate, via a mechanism mainly constituted of a mechanical linkage, a swinging belt, a conveyance belt and a grate. Mechanism analysis illustrates that uniform pellet pavements demand the frontend of the swinging belt oscillate at a constant angular velocity. Subsequently, kinetic models are formulated to relate oscillatory movements of the swinging belt's frontend to rotations of a crank link driven by a motor. On basis of kinetic analysis of the pellet feeding mechanism, a cubic B-spline model is built for numerically computing discrete frequencies to be modulated during a motor rotation. Subsequently, the pellet feeding control <span class="hlt">system</span> is presented in terms of compositional hardware and software components, and their functional relationships. Finally, pellet feeding experiments are carried out to demonstrate that the control <span class="hlt">system</span> is effective, reliable and superior to conventional methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22882957','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22882957"><span id="translatedtitle">Morphological and physicochemical characteristics of <span class="hlt">iron</span> corrosion scales formed under different water source histories in a drinking water distribution <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Fan; Shi, Baoyou; Gu, Junnong; Wang, Dongsheng; Yang, Min</p> <p>2012-10-15</p> <p>The corrosion scales on <span class="hlt">iron</span> pipes could have great impact on the water quality in drinking water distribution <span class="hlt">systems</span> (DWDS). Unstable and less protective corrosion scale is one of the main factors causing "discolored water" issues when quality of water entering into distribution <span class="hlt">system</span> changed significantly. The morphological and physicochemical characteristics of corrosion scales formed under different source water histories in duration of about two decades were systematically investigated in this work. Thick corrosion scales or densely distributed corrosion tubercles were mostly found in pipes <span class="hlt">transporting</span> surface water, but thin corrosion scales and hollow tubercles were mostly discovered in pipes <span class="hlt">transporting</span> groundwater. Magnetite and goethite were main constituents of <span class="hlt">iron</span> corrosion products, but the mass ratio of magnetite/goethite (M/G) was significantly different depending on the corrosion scale structure and water source conditions. Thick corrosion scales and hard shell of tubercles had much higher M/G ratio (>1.0), while the thin corrosion scales had no magnetite detected or with much lower M/G ratio. The M/G ratio could be used to identify the characteristics and evaluate the performances of corrosion scales formed under different water conditions. Compared with the pipes <span class="hlt">transporting</span> ground water, the pipes <span class="hlt">transporting</span> surface water were more seriously corroded and could be in a relatively more active corrosion status all the time, which was implicated by relatively higher siderite, green rust and total <span class="hlt">iron</span> contents in their corrosion scales. Higher content of unstable ferric components such as γ-FeOOH, β-FeOOH and amorphous <span class="hlt">iron</span> oxide existed in corrosion scales of pipes receiving groundwater which was less corroded. Corrosion scales on groundwater pipes with low magnetite content had higher surface area and thus possibly higher sorption capacity. The primary trace inorganic elements in corrosion products were Br and heavy metals. Corrosion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22882957','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22882957"><span id="translatedtitle">Morphological and physicochemical characteristics of <span class="hlt">iron</span> corrosion scales formed under different water source histories in a drinking water distribution <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Fan; Shi, Baoyou; Gu, Junnong; Wang, Dongsheng; Yang, Min</p> <p>2012-10-15</p> <p>The corrosion scales on <span class="hlt">iron</span> pipes could have great impact on the water quality in drinking water distribution <span class="hlt">systems</span> (DWDS). Unstable and less protective corrosion scale is one of the main factors causing "discolored water" issues when quality of water entering into distribution <span class="hlt">system</span> changed significantly. The morphological and physicochemical characteristics of corrosion scales formed under different source water histories in duration of about two decades were systematically investigated in this work. Thick corrosion scales or densely distributed corrosion tubercles were mostly found in pipes <span class="hlt">transporting</span> surface water, but thin corrosion scales and hollow tubercles were mostly discovered in pipes <span class="hlt">transporting</span> groundwater. Magnetite and goethite were main constituents of <span class="hlt">iron</span> corrosion products, but the mass ratio of magnetite/goethite (M/G) was significantly different depending on the corrosion scale structure and water source conditions. Thick corrosion scales and hard shell of tubercles had much higher M/G ratio (>1.0), while the thin corrosion scales had no magnetite detected or with much lower M/G ratio. The M/G ratio could be used to identify the characteristics and evaluate the performances of corrosion scales formed under different water conditions. Compared with the pipes <span class="hlt">transporting</span> ground water, the pipes <span class="hlt">transporting</span> surface water were more seriously corroded and could be in a relatively more active corrosion status all the time, which was implicated by relatively higher siderite, green rust and total <span class="hlt">iron</span> contents in their corrosion scales. Higher content of unstable ferric components such as γ-FeOOH, β-FeOOH and amorphous <span class="hlt">iron</span> oxide existed in corrosion scales of pipes receiving groundwater which was less corroded. Corrosion scales on groundwater pipes with low magnetite content had higher surface area and thus possibly higher sorption capacity. The primary trace inorganic elements in corrosion products were Br and heavy metals. Corrosion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS22B..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS22B..03S"><span id="translatedtitle">Basin-Scale <span class="hlt">Transport</span> of Hydrothermal <span class="hlt">Iron</span>, Manganese and Aluminum Across the Eastern South Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sedwick, P. N.; Resing, J. A.; Sohst, B. M.; Jenkins, W. J.; German, C. R.; Moffett, J. W.</p> <p>2014-12-01</p> <p>The U.S. GEOTRACES Eastern Pacific Zonal Transect cruise (GEOTRACES GP06) examined the water-column distribution of trace elements between Peru and Tahiti, crossing the southern East Pacific Rise (EPR) midway along the cruise track. Shipboard measurements made along this ocean section reveal the mid-depth lateral <span class="hlt">transport</span> of hydrothermal dissolved <span class="hlt">iron</span> (dFe), manganese (dMn) and aluminum (dAl) over a distance of more than 4,000 km, from the EPR westward into the deep South Pacific basin. Post-cruise measurements of the conservative hydrothermal tracer helium-3 indicate the loss of at least 85% of the hydrothermal dFe over a distance of ~80 km west from the ridge axis, presumably as a result of oxidation, scavenging and precipitation. Further west of the ridge axis, dFe and excess helium-3 (3Hexs) are linearly correlated (r2 = 0.99), showing a more than 4-fold conservative dilution of hydrothermal dFe over a distance of ~4000 km. This behavior may reflect the lateral <span class="hlt">transport</span> of <span class="hlt">iron</span> as relatively unreactive, colloidal oxyhydroxides; ongoing analyses of cruise samples by other groups will provide data to test this hypothesis. The loss of hydrothermal dMn relative to 3Hexs extends over a greater distance than for dFe, as far as ~250 km to the west of the ridge axis, beyond which dMn exhibits nearly conservative behavior. The hydrothermal dAl anomaly appears to extend over 3,000 km west of the EPR, and is not readily explained based on the known composition of ridge-axis vent fluids. The linear dFe versus 3Hexs relationship in the off-axis hydrothermal plume has a slope of 5.6 x 106 mol/mol, which falls roughly between values estimated for the western South Pacific and the South Atlantic basins. If we assume that our dFe and 3He data are generally representative of mid-ocean ridge hydrothermal emissions, then the estimated global hydrothermal 3He efflux of 530 mol/y yields an effective hydrothermal dFe input of 2.9 Gmol/y to the ocean interior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10190700','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10190700"><span id="translatedtitle">Fire and materials modeling for <span class="hlt">transportation</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Skocypec, R.D.; Gritzo, L.A.; Moya, J.L.; Nicolette, V.F.; Tieszen, S.R.; Thomas, R.</p> <p>1994-10-01</p> <p>Fire is an important threat to the safety of <span class="hlt">transportation</span> <span class="hlt">systems</span>. Therefore, understanding the effects of fire (and its interaction with materials) on <span class="hlt">transportation</span> <span class="hlt">systems</span> is crucial to quantifying and mitigating the impact of fire on the safety of those <span class="hlt">systems</span>. Research and development directed toward improving the fire safety of <span class="hlt">transportation</span> <span class="hlt">systems</span> must address a broad range of phenomena and technologies, including: crash dynamics, fuel dispersion, fire environment characterization, material characterization, and <span class="hlt">system</span>/cargo thermal response modeling. In addition, if the goal of the work is an assessment and/or reduction of risk due to fires, probabilistic risk assessment technology is also required. The research currently underway at Sandia National Laboratories in each of these areas is summarized in this paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol1/pdf/CFR-2011-title49-vol1-sec37-25.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol1/pdf/CFR-2011-title49-vol1-sec37-25.pdf"><span id="translatedtitle">49 CFR 37.25 - University <span class="hlt">transportation</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 1 2011-10-01 2011-10-01 false University <span class="hlt">transportation</span> <span class="hlt">systems</span>. 37.25 Section 37.25 <span class="hlt">Transportation</span> Office of the Secretary of <span class="hlt">Transportation</span> <span class="hlt">TRANSPORTATION</span> SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Applicability § 37.25 University <span class="hlt">transportation</span> <span class="hlt">systems</span>....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol1/pdf/CFR-2013-title49-vol1-sec37-25.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol1/pdf/CFR-2013-title49-vol1-sec37-25.pdf"><span id="translatedtitle">49 CFR 37.25 - University <span class="hlt">transportation</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 1 2013-10-01 2013-10-01 false University <span class="hlt">transportation</span> <span class="hlt">systems</span>. 37.25 Section 37.25 <span class="hlt">Transportation</span> Office of the Secretary of <span class="hlt">Transportation</span> <span class="hlt">TRANSPORTATION</span> SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Applicability § 37.25 University <span class="hlt">transportation</span> <span class="hlt">systems</span>....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol1/pdf/CFR-2012-title49-vol1-sec37-25.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol1/pdf/CFR-2012-title49-vol1-sec37-25.pdf"><span id="translatedtitle">49 CFR 37.25 - University <span class="hlt">transportation</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 1 2012-10-01 2012-10-01 false University <span class="hlt">transportation</span> <span class="hlt">systems</span>. 37.25 Section 37.25 <span class="hlt">Transportation</span> Office of the Secretary of <span class="hlt">Transportation</span> <span class="hlt">TRANSPORTATION</span> SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Applicability § 37.25 University <span class="hlt">transportation</span> <span class="hlt">systems</span>....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol1/pdf/CFR-2010-title49-vol1-sec37-25.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol1/pdf/CFR-2010-title49-vol1-sec37-25.pdf"><span id="translatedtitle">49 CFR 37.25 - University <span class="hlt">transportation</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 1 2010-10-01 2010-10-01 false University <span class="hlt">transportation</span> <span class="hlt">systems</span>. 37.25 Section 37.25 <span class="hlt">Transportation</span> Office of the Secretary of <span class="hlt">Transportation</span> <span class="hlt">TRANSPORTATION</span> SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Applicability § 37.25 University <span class="hlt">transportation</span> <span class="hlt">systems</span>....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3077886','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3077886"><span id="translatedtitle">Ascorbic Acid Offsets the Inhibitory Effect of Bioactive Dietary Polyphenolic Compounds on Transepithelial <span class="hlt">Iron</span> <span class="hlt">Transport</span> in Caco-2 Intestinal Cells12</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kim, Eun-Young; Ham, Soo-Kyung; Bradke, Daniel; Ma, Qianyi; Han, Okhee</p> <p>2011-01-01</p> <p>We previously reported that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) at high concentration nearly blocked intestinal <span class="hlt">iron</span> <span class="hlt">transport</span> across the enterocyte. In this study, we aimed to determine whether small amounts of EGCG, GSE, and green tea extract (GT) are capable of inhibiting <span class="hlt">iron</span> absorption, to examine if ascorbic acid counteracts the inhibitory action of polyphenols on <span class="hlt">iron</span> absorption, and to explore the mechanisms of polyphenol-mediated apical <span class="hlt">iron</span> uptake and basolateral <span class="hlt">iron</span> release. An55Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT using Caco-2 intestinal cells. Polyphenols were found to inhibit the transepithelial 55Fe <span class="hlt">transport</span> in a dose-dependent manner. The addition of ascorbic acid offset the inhibitory effects of polyphenols on <span class="hlt">iron</span> <span class="hlt">transport</span>. Ascorbic acid modulated the transepithelial <span class="hlt">iron</span> <span class="hlt">transport</span> without changing the apical <span class="hlt">iron</span> uptake and the expression of ferroportin-1 protein in the presence of EGCG. The polyphenol-mediated apical <span class="hlt">iron</span> uptake was inhibited by membrane impermeable Fe2+ chelators (P < 0.001), but at a low temperature (4°C), the apical <span class="hlt">iron</span> uptake was still higher than the control values at 37°C (P < 0.001). These results suggest that polyphenols enhance the apical <span class="hlt">iron</span> uptake partially by reducing the conversion of ferric to ferrous ions and possibly by increasing the uptake of polyphenol-<span class="hlt">iron</span> complexes via the energy-independent pathway. The present results indicate that the inhibitory effects of dietary polyphenols on <span class="hlt">iron</span> absorption can be offset by ascorbic acid. Further studies are needed to confirm the current findings in vivo. PMID:21430251</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940004518&hterms=System+transport+articulated&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSystem%2Btransport%2Barticulated','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940004518&hterms=System+transport+articulated&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSystem%2Btransport%2Barticulated"><span id="translatedtitle">Design of a lunar <span class="hlt">transportation</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sankaravelu, A.; Goddard, H.; Gold, R.; Greenwell, S.; Lander, J.; Nordell, B.; Stepp, K.; Styer, M.</p> <p>1989-01-01</p> <p>The development of a good <span class="hlt">transportation</span> infrastructure is a major requirement for the establishment of a permanent lunar base. <span class="hlt">Transportation</span> is characterized by the technology available in a specific time frame and the need to <span class="hlt">transport</span> personnel and cargo between Earth and Moon, and between lunar bases. In our study, attention was first focused on developing a <span class="hlt">transportation</span> <span class="hlt">system</span> for the first generation lunar base. As a first step, a tracked-type multipurpose lunar <span class="hlt">transportation</span> vehicle was considered as a possible mode of <span class="hlt">transportation</span> and a detailed study was conducted on the various aspects of the vehicle. Since the vehicle is composed of many moving parts, exposing it to the environment of the Moon, where fine dust particles are prevalent, can cause problems associated with lubrication and friction. The vehicle also posed problems concerning weight and power. Hence, several modifications were made to the above design ideas conceptually, and a Lunar Articulated Remote <span class="hlt">Transportation</span> <span class="hlt">System</span> (Lunar ARTS) is proposed as a more effective alternative with the following objectives: (1) minimizing the <span class="hlt">transportation</span> of construction material and fuel from Earth or maximizing the use of the lunar material; (2) use of novel materials and light-weight structures; (3) use of new manufacturing methods and technology such as magnetic levitation using superconducting materials; and (4) innovative concepts of effectively utilizing the exotic lunar conditions, i.e., high thermal gradients, lack of atmosphere, lower gravity, etc. To achieve the above objectives of designing <span class="hlt">transportation</span> <span class="hlt">systems</span> from concept to operation, the project was planned in three phases: (1) conceptual design; (2) detailed analysis and synthesis; and (3) construction, testing, evaluation, and operation. In this project, both phases 1 and 2 have been carried out and work on phase 3 is in progress. In this paper, the details of the Lunar ARTS are discussed and the future work on the vehicle are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27150508','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27150508"><span id="translatedtitle">Gallium and its competing roles with <span class="hlt">iron</span> in biological <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chitambar, Christopher R</p> <p>2016-08-01</p> <p>Gallium, a group IIIa metal, shares chemical properties with <span class="hlt">iron</span>. Studies have shown that gallium-based compounds have potential therapeutic activity against certain cancers and infectious microorganisms. By functioning as an <span class="hlt">iron</span> mimetic, gallium perturbs <span class="hlt">iron</span>-dependent proliferation processes in tumor cells. Gallium's action on <span class="hlt">iron</span> homeostasis leads to disruption of ribonucleotide reductase, mitochondrial function, and the regulation of transferrin receptor and ferritin. In addition, gallium nitrate stimulates an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Gallium's anti-infective activity against bacteria and fungi results from disruption of microbial <span class="hlt">iron</span> utilization through mechanisms which include gallium binding to siderophores and downregulation of bacterial <span class="hlt">iron</span> uptake. Gallium compounds lack cross-resistance to conventional chemotherapeutic drugs and antibiotics thus making them attractive agents for drug development. This review will focus on the mechanisms of action of gallium with emphasis on its interaction with <span class="hlt">iron</span> and <span class="hlt">iron</span> proteins. PMID:27150508</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27150508','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27150508"><span id="translatedtitle">Gallium and its competing roles with <span class="hlt">iron</span> in biological <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chitambar, Christopher R</p> <p>2016-08-01</p> <p>Gallium, a group IIIa metal, shares chemical properties with <span class="hlt">iron</span>. Studies have shown that gallium-based compounds have potential therapeutic activity against certain cancers and infectious microorganisms. By functioning as an <span class="hlt">iron</span> mimetic, gallium perturbs <span class="hlt">iron</span>-dependent proliferation processes in tumor cells. Gallium's action on <span class="hlt">iron</span> homeostasis leads to disruption of ribonucleotide reductase, mitochondrial function, and the regulation of transferrin receptor and ferritin. In addition, gallium nitrate stimulates an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Gallium's anti-infective activity against bacteria and fungi results from disruption of microbial <span class="hlt">iron</span> utilization through mechanisms which include gallium binding to siderophores and downregulation of bacterial <span class="hlt">iron</span> uptake. Gallium compounds lack cross-resistance to conventional chemotherapeutic drugs and antibiotics thus making them attractive agents for drug development. This review will focus on the mechanisms of action of gallium with emphasis on its interaction with <span class="hlt">iron</span> and <span class="hlt">iron</span> proteins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21055273','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21055273"><span id="translatedtitle">Multiphase Model of Heat and Mass <span class="hlt">Transport</span> during Laser Alloying of <span class="hlt">Iron</span> with Electrodeposited Chromium Layer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Didenko, T.; Kusinski, J.; Kusinski, G.</p> <p>2008-02-15</p> <p>The aim of this research was to study the laser alloying process of <span class="hlt">iron</span> with chromium. In the paper, a multiphase model of mass and heat transfer for the laser alloying is presented. Laser melting of the chromium layer and the substrate was performed using a continuous laser source operated with a TEM{sub 10} mode, with constant beam diameter ({phi}), scanning velocity (V) and varied output beam power. The partial differential equations of the conservation of mass, momentum and energy in the melted pool for multiphase <span class="hlt">system</span> were solved. The distribution of chromium in <span class="hlt">iron</span> after laser alloying was obtained by including the Volume of Fluid algorithm in the model. The results of the computations were compared with the experimental evaluation of the microstructure and the chromium concentration, which were based on scanning electron microscopy and x-ray microanalysis (Energy Dispersive Spectroscopy) of the laser alloyed layers. The comparison of computational calculations and experimental results is presented and a good accuracy of the proposed model is shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9435E..22B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9435E..22B"><span id="translatedtitle">Hyperspectral imaging utility for <span class="hlt">transportation</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bridgelall, Raj; Rafert, J. Bruce; Tolliver, Denver</p> <p>2015-03-01</p> <p>The global <span class="hlt">transportation</span> <span class="hlt">system</span> is massive, open, and dynamic. Existing performance and condition assessments of the complex interacting networks of roadways, bridges, railroads, pipelines, waterways, airways, and intermodal ports are expensive. Hyperspectral imaging is an emerging remote sensing technique for the non-destructive evaluation of multimodal <span class="hlt">transportation</span> infrastructure. Unlike panchromatic, color, and infrared imaging, each layer of a hyperspectral image pixel records reflectance intensity from one of dozens or hundreds of relatively narrow wavelength bands that span a broad range of the electromagnetic spectrum. Hence, every pixel of a hyperspectral scene provides a unique spectral signature that offers new opportunities for informed decision-making in <span class="hlt">transportation</span> <span class="hlt">systems</span> development, operations, and maintenance. Spaceborne <span class="hlt">systems</span> capture images of vast areas in a short period but provide lower spatial resolution than airborne <span class="hlt">systems</span>. Practitioners use manned aircraft to achieve higher spatial and spectral resolution, but at the price of custom missions and narrow focus. The rapid size and cost reduction of unmanned aircraft <span class="hlt">systems</span> promise a third alternative that offers hybrid benefits at affordable prices by conducting multiple parallel missions. This research formulates a theoretical framework for a pushbroom type of hyperspectral imaging <span class="hlt">system</span> on each type of data acquisition platform. The study then applies the framework to assess the relative potential utility of hyperspectral imaging for previously proposed remote sensing applications in <span class="hlt">transportation</span>. The authors also introduce and suggest new potential applications of hyperspectral imaging in <span class="hlt">transportation</span> asset management, network performance evaluation, and risk assessments to enable effective and objective decision- and policy-making.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23614641','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23614641"><span id="translatedtitle">Antagonistic effects of humic acid and <span class="hlt">iron</span> oxyhydroxide grain-coating on biochar nanoparticle <span class="hlt">transport</span> in saturated sand.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Dengjun; Zhang, Wei; Zhou, Dongmei</p> <p>2013-05-21</p> <p>Biochar land application may result in multiple agronomic and environmental benefits (e.g., carbon sequestration, improving soil quality, and immobilizing environmental contaminants). However, our understanding of biochar particle <span class="hlt">transport</span> is largely unknown in natural environments with significant heterogeneity in solid (e.g., patches of <span class="hlt">iron</span> oxyhydroxide coating) and solution chemistry (e.g., the presence of natural organic matter), which represents a critical knowledge gap in assessing the environmental impact of biochar land application. <span class="hlt">Transport</span> and retention kinetics of nanoparticles (NPs) from wheat straw biochars produced at two pyrolysis temperatures (i.e., 350 and 550 °C) were investigated in water-saturated sand columns at environmentally relevant concentrations of dissolved humic acid (HA, 0, 1, 5, and 10 mg L(-1)) and fractional surface coverage of <span class="hlt">iron</span> oxyhydroxide coatings on sand grains (ω, 0.16, 0.28, and 0.40). <span class="hlt">Transport</span> of biochar NPs increased with increasing HA concentration, largely because of enhanced repulsive interaction energy between biochar NPs and sand grains. Conversely, <span class="hlt">transport</span> of biochar NPs decreased significantly with increasing ω due to enhanced electrostatic attraction between negatively charged biochar NPs and positively charged <span class="hlt">iron</span> oxyhydroxides. At a given ω of 0.28, biochar NPs were less retained with increasing HA concentration due to increased electrosteric repulsion between biochar NPs and sand grains. Experimental breakthrough curves and retention profiles were well described using a two-site kinetic retention model that accounted for Langmuirian blocking or random sequential adsorption at one site. Consistent with the blocking effect, the often observed flat retention profiles stemmed from decreased retention rate and/or maximum retention capacity at a higher HA concentration or smaller ω. The antagonistic effects of HA and <span class="hlt">iron</span> oxyhydroxide grain-coating imparted on the mobility of biochar NPs suggest that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24361705','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24361705"><span id="translatedtitle">Straining of polyelectrolyte-stabilized nanoscale zero valent <span class="hlt">iron</span> particles during <span class="hlt">transport</span> through granular porous media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raychoudhury, Trishikhi; Tufenkji, Nathalie; Ghoshal, Subhasis</p> <p>2014-03-01</p> <p>In this study, the relevance of straining of nano-sized particles of zero valent <span class="hlt">iron</span> coated with carboxymethyl cellulose (CMC-NZVI) during <span class="hlt">transport</span> in model subsurface porous media is assessed. Although deposition of polyelectrolyte stabilized-NZVI on granular subsurface media due to physicochemical attachment processes has been reported previously, there is limited knowledge on the significance of the collector (sand) diameter on the deposition and spatial distribution of the retention of such nanoparticles. Experiments were conducted to assess the <span class="hlt">transport</span> of CMC-NZVI in columns packed with four different-sized sands of mean diameter of 775 μm, 510 μm, 250 μm and 150 μm and at three different particle concentrations of 0.085 g L(-1), 0.35 g L(-1) and 1.70 g L(-1). CMC-NZVI effluent concentrations decreased with smaller sand diameters. High CMC-NZVI particle retention near the inlet, particularly for the finer sands was observed, even with a low ionic strength of 0.1 mM for the electrolyte medium. These observations are consistent with particle retention in porous media due to straining and/or wedging. Two colloid <span class="hlt">transport</span> models, one considering particle retention by physicochemical deposition and detachment of those deposited particles, and the other considering particle retention by straining along with particle deposition and detachment, were fitted to the experimental data. The model accounting for straining shows a better fit, especially to the CMC-NZVI retention data along the length of the column. The straining rate coefficients decreased with larger sand diameters. This study demonstrates that CMC-NZVI particles, despite of their small size (hydrodynamic diameters of 167-185 nm and transmission electron microscopy imaged diameters of approximately 85 nm), may be removed by straining during <span class="hlt">transport</span>, especially through fine granular subsurface media. The tailing effect, observed in the particle breakthrough curves, is attributed to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22334148','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22334148"><span id="translatedtitle">Not planning a sustainable <span class="hlt">transport</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Finnveden, Göran Åkerman, Jonas</p> <p>2014-04-01</p> <p>The overall objective of the Swedish <span class="hlt">transport</span> policy is to ensure the economically efficient and sustainable provision of <span class="hlt">transport</span> services for people and business throughout the country. More specifically, the <span class="hlt">transport</span> sector shall, among other things, contribute to the achievement of environmental quality objectives in which the development of the <span class="hlt">transport</span> <span class="hlt">system</span> plays an important role in the achievement of the objectives. The aim of this study is to analyse if current <span class="hlt">transport</span> planning supports this policy. This is done by analysing two recent cases: the National Infrastructure Plan 2010–2021, and the planning of Bypass Stockholm, a major road investment. Our results show that the plans are in conflict with several of the environmental quality objectives. Another interesting aspect of the planning processes is that the long-term climate goals are not included in the planning processes, neither as a clear goal nor as factor that will influence future <span class="hlt">transport</span> <span class="hlt">systems</span>. In this way, the long-term sustainability aspects are not present in the planning. We conclude that the two cases do not contribute to a sustainable <span class="hlt">transport</span> <span class="hlt">system</span>. Thus, several changes must be made in the processes, including putting up clear targets for emissions. Also, the methodology for the environmental assessments needs to be further developed and discussed. - Highlights: • Two cases are studied to analyse if current planning supports a sustainable <span class="hlt">transport</span> <span class="hlt">system</span>. • Results show that the plans are in conflict with several of the environmental quality objectives. • Long-term climate goals are not included in the planning processes. • Current practices do not contribute to a sustainable planning processes. • Methodology and process for environmental assessments must be further developed and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940014197','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940014197"><span id="translatedtitle">Human <span class="hlt">Transportation</span> <span class="hlt">System</span> (HTS) study, volume 1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lance, N.; Geyer, M. S.; Gaunce, M. T.</p> <p>1993-01-01</p> <p>Work completed under the Human <span class="hlt">Transportation</span> <span class="hlt">System</span> Study is summarized. This study was conducted by the New Initiatives Office at JSC with the technical support of Boeing, General Dynamics, Lockheed, McDonnell-Douglas, Martin Marietta, and Rockwell. The study was designed to generate information on determining the appropriate path to follow for new <span class="hlt">system</span> development to meet the Nation's space <span class="hlt">transportation</span> needs. The study evaluates 18 <span class="hlt">transportation</span> architecture options using a parametric set of mission requirements. These options include use of current <span class="hlt">systems</span> as well as proposed <span class="hlt">systems</span> to assess the impact of various considerations, such as the cost of alternate access, or the benefit of separating people and cargo. The architecture options are compared to each other with six measurable evaluation criteria or attributes. They are the following: funding profile, human safety, probability of mission success, architecture cost risk, launch schedule confidence, and environmental impact. Values for these attributes are presented for the architecture options, with pertinent conclusions and recommendations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940014196','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940014196"><span id="translatedtitle">Human <span class="hlt">Transportation</span> <span class="hlt">System</span> (HTS) study: Executive summary</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lance, N.; Geyer, M. S.; Gaunce, M. T.</p> <p>1993-01-01</p> <p>Work completed under the Human <span class="hlt">Transportation</span> <span class="hlt">System</span> Study is summarized. This study was conducted by the New Initiatives Office at JSC with the technical support of Boeing, General Dynamics, Lockheed, McDonnell-Douglas, Martin Marietta, and Rockwell. The study was designed to generate information on determining the appropriate path to follow for new <span class="hlt">system</span> development to meet the Nation's space <span class="hlt">transportation</span> needs. The study evaluates 18 <span class="hlt">transportation</span> architecture options using a parametric set of mission requirements. These options include use of current <span class="hlt">systems</span> as well as proposed <span class="hlt">systems</span> to assess the impact of various considerations, such as the cost of alternate access, or the benefit of separating people and cargo. The architecture options are compared to each other with six measurable evaluation criteria or attributes. They are the following: funding profile, human safety, probability of mission success, architecture cost risk, launch schedule confidence, and environmental impact. Values for these attributes are presented for the architecture options, with pertinent conclusions and recommendations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17588639','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17588639"><span id="translatedtitle">Column studies on <span class="hlt">transport</span> of deicing additive benzotriazole in a sandy aquifer and a zerovalent <span class="hlt">iron</span> barrier.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jia, Yu; Breedveld, Gijs D; Aagaard, Per</p> <p>2007-11-01</p> <p>Benzotriazole (BTA), a chemical with wide industrial applications, is a typical additive in deicer/anti-icer used at airport. To achieve a better understanding of the <span class="hlt">transport</span> behaviour and environmental fate of BTA, laboratory column studies have been performed on subsoil samples from Oslo Airport, Gardermoen. To explore possibilities for aquifer remediation, BTA behaviour was also studied in a column of granular zerovalent <span class="hlt">iron</span> (Fe(0)). The subsoil column study demonstrates a very limited retardation of BTA. Consecutive loadings of BTA of the subsoil column showed no change of the break-through curve (BTC) and complete desorption was observed. The sorption behaviour of BTA to metallic <span class="hlt">iron</span> (Fe(0)) was rather complex. Considerable retardation was observed in the Fe(0) column and repeated BTA loading resulted in an earlier break-through. Between 20% and 50% of the input concentration was retained permanently in the <span class="hlt">iron</span> (Fe(0)) column. The BTA sorption to metallic <span class="hlt">iron</span> was found to be enhanced by chloride which lowered the break-through concentration (i.e the C/C(0) plateau). The fraction of BTA remaining in the <span class="hlt">iron</span> column was found to vary with the flow rate, indicating a time dependant multilayer sorption mechanism. The steady increase in the amount of adsorbed BTA to the <span class="hlt">iron</span> column during loading corresponds to a rather strong bonding of 4-15 BTA layers to the <span class="hlt">iron</span> surface. A very slow desorption of BTA was observed; even after flushing with 753 pore volumes of BTA free water, 7.5% of the BTA remained in the column. A geochemical model was developed based on PHREEQC-2 to simulate the sorption and <span class="hlt">transport</span> of BTA in the tested materials. The BTA sorption was modelled with Freundlich sorption isotherms, as earlier determined in batch experiments. A slight adjustment of the Freundlich parameters was required to fit the observed column break-through. However, our model was not able to simulate the long-term retainment of BTA in the granular <span class="hlt">iron</span> columns. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850020632','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850020632"><span id="translatedtitle">Advanced secondary power <span class="hlt">system</span> for <span class="hlt">transport</span> aircraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoffman, A. C.; Hansen, I. G.; Beach, R. F.; Plencner, R. M.; Dengler, R. P.; Jefferies, K. S.; Frye, R. J.</p> <p>1985-01-01</p> <p>A concept for an advanced aircraft power <span class="hlt">system</span> was identified that uses 20-kHz, 440-V, sin-wave power distribution. This <span class="hlt">system</span> was integrated with an electrically powered flight control <span class="hlt">system</span> and with other aircraft <span class="hlt">systems</span> requiring secondary power. The resulting all-electric secondary power configuration reduced the empty weight of a modern 200-passenger, twin-engine <span class="hlt">transport</span> by 10 percent and the mission fuel by 9 percent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26498094','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26498094"><span id="translatedtitle">Comparison of the <span class="hlt">transport</span> of the aggregates of nanoscale zerovalent <span class="hlt">iron</span> under vertical and horizontal flow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Jing; Ghoshal, Subhasis</p> <p>2016-02-01</p> <p>Direct injection of nanoscale zerovalent <span class="hlt">iron</span> (NZVI) particles is being considered for remediation of contaminated sites. However, the <span class="hlt">transport</span> characteristics of NZVI under horizontal flow conditions are not fully understood. In this study, NZVI particles were stabilized with carboxymethyl cellulose (CMC) and injected in vertical and horizontal columns to compare the effects of the flow direction on the <span class="hlt">transport</span>. Columns were packed with sand of mean grain diameters of 180, 340 or 1140 µm (referred to as fine, intermediate and coarse sand, respectively), and were injected with CMC-NZVI suspensions of 0.3, 1 or 3 g Fe L(-1). Experimental breakthrough curves showed that with the coarse and intermediate sands, the steady-state effluent concentration in the horizontal column were up to 84% lower than those in the vertical column regardless of the initial NZVI concentration. However, in the fine sand the differences were insignificant, except at the highest NZVI particle concentration. Additionally, in the horizontally-oriented columns containing the coarse or intermediated sand, NZVI aggregates particles were non-uniformly distributed in the cross-section of the columns and there higher deposition in the bottom-half of the cross-section due to gravity effects. These deposition patterns can be accounted for, in part, by the gravitational settling of the large aggregates of NZVI, especially at high NZVI concentrations. A particle trajectory analysis in three dimensions demonstrated that under horizontal flow, gravity forces resulted in lower deposition of NZVI on the bottom-half of a single collector, as particles approaching the bottom-half of the collector were deflected by gravity to collectors below. PMID:26498094</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26498094','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26498094"><span id="translatedtitle">Comparison of the <span class="hlt">transport</span> of the aggregates of nanoscale zerovalent <span class="hlt">iron</span> under vertical and horizontal flow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Jing; Ghoshal, Subhasis</p> <p>2016-02-01</p> <p>Direct injection of nanoscale zerovalent <span class="hlt">iron</span> (NZVI) particles is being considered for remediation of contaminated sites. However, the <span class="hlt">transport</span> characteristics of NZVI under horizontal flow conditions are not fully understood. In this study, NZVI particles were stabilized with carboxymethyl cellulose (CMC) and injected in vertical and horizontal columns to compare the effects of the flow direction on the <span class="hlt">transport</span>. Columns were packed with sand of mean grain diameters of 180, 340 or 1140 µm (referred to as fine, intermediate and coarse sand, respectively), and were injected with CMC-NZVI suspensions of 0.3, 1 or 3 g Fe L(-1). Experimental breakthrough curves showed that with the coarse and intermediate sands, the steady-state effluent concentration in the horizontal column were up to 84% lower than those in the vertical column regardless of the initial NZVI concentration. However, in the fine sand the differences were insignificant, except at the highest NZVI particle concentration. Additionally, in the horizontally-oriented columns containing the coarse or intermediated sand, NZVI aggregates particles were non-uniformly distributed in the cross-section of the columns and there higher deposition in the bottom-half of the cross-section due to gravity effects. These deposition patterns can be accounted for, in part, by the gravitational settling of the large aggregates of NZVI, especially at high NZVI concentrations. A particle trajectory analysis in three dimensions demonstrated that under horizontal flow, gravity forces resulted in lower deposition of NZVI on the bottom-half of a single collector, as particles approaching the bottom-half of the collector were deflected by gravity to collectors below.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1082342','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1082342"><span id="translatedtitle">Alternative battery <span class="hlt">systems</span> for <span class="hlt">transportation</span> uses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Michael Thackeray</p> <p>2012-07-25</p> <p>Argonne Distinguished Fellow Michael Thackeray highlights the need for alternative battery <span class="hlt">systems</span> for <span class="hlt">transportation</span> uses. Such <span class="hlt">systems</span> will not only need to be smaller, lighter and more energy dense, but also able to make electric vehicles more competitive with internal combustion engine vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1279568-monte-carlo-nucleon-meson-transport-code-system','SCIGOV-ESTSC'); return false;" href="http://www.osti.gov/scitech/biblio/1279568-monte-carlo-nucleon-meson-transport-code-system"><span id="translatedtitle">Monte Carlo Nucleon Meson <span class="hlt">Transport</span> Code <span class="hlt">System</span>.</span></a></p> <p><a target="_blank" href=""></a></p> <p></p> <p>2000-11-17</p> <p>Version 00 NMTC/JAERI97 is an upgraded version of the code <span class="hlt">system</span> NMTC/JAERI, which was developed in 1982 at JAERI and is based on the CCC-161/NMTC code <span class="hlt">system</span>. NMTC/JAERI97 simulates high energy nuclear reactions and nucleon-meson <span class="hlt">transport</span> processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/sciencecinema/biblio/1082342','SCIGOVIMAGE-SCICINEMA'); return false;" href="http://www.osti.gov/sciencecinema/biblio/1082342"><span id="translatedtitle">Alternative battery <span class="hlt">systems</span> for <span class="hlt">transportation</span> uses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/sciencecinema/">ScienceCinema</a></p> <p>Michael Thackeray</p> <p>2016-07-12</p> <p>Argonne Distinguished Fellow Michael Thackeray highlights the need for alternative battery <span class="hlt">systems</span> for <span class="hlt">transportation</span> uses. Such <span class="hlt">systems</span> will not only need to be smaller, lighter and more energy dense, but also able to make electric vehicles more competitive with internal combustion engine vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12949888','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12949888"><span id="translatedtitle">Localization of the <span class="hlt">iron</span> <span class="hlt">transport</span> proteins Mobilferrin and DMT-1 in the duodenum: the surprising role of mucin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Simovich, Marcia; Hainsworth, Lucille N; Fields, P A; Umbreit, Jay N; Conrad, Marcel E</p> <p>2003-09-01</p> <p>There are two pathways for inorganic <span class="hlt">iron</span> uptake in the intestine, the ferric pathway, mediated by the key protein mobilferrin, and the ferrous pathway, mediated by DMT-1. Previous studies reported that the amount of DMT-1 increased in the intestinal mucosa in <span class="hlt">iron</span> deficiency and the increase was seen in the apical portion of the villus of the duodenal mucosa. Mobilferrin did not quantitatively increase but became localized at the cell membrane. However, studies on fresh tissue have not previously been performed and the localization to the microvillae has not been demonstrated. In order to more definitively localize these proteins immunofluorescent and electron microscopic studies were undertaken. Samples were also subjected to biochemical analysis and Western analysis. In <span class="hlt">iron</span>-deficient animals both DMT-1 and Mobilferrin were concentrated in the apical surface of the villae. Electron microscopy revealed that the majority of this increase in the amount of these proteins near the luminal surface was due to increased binding of the proteins to mucin in vesicles near the surface. A significant portion of the <span class="hlt">iron</span> <span class="hlt">transport</span> proteins was localized in the goblet cells and outside the cell in the luminal mucin, as demonstrated by immunofluorescence, electron microscopy, and isolation of the mucin by cesium chloride gradient centrifugation and Western analysis. A new model for the <span class="hlt">transport</span> of metal ions was suggested. The metal <span class="hlt">transport</span> proteins travel from vesicles inside the cell out to the lumen mucin. This increases the surface area and allows a greater portion of the lumen contents to be exposed to the binding proteins. Once the metal is bound to the externalized protein it is internalized into the cell. This explains many of the unique properties of the <span class="hlt">iron</span>-binding proteins and suggests that it may be a more general model for the absorption of other nutrients.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22298007','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22298007"><span id="translatedtitle">Refolding, purification and crystallization of the FrpB outer membrane <span class="hlt">iron</span> <span class="hlt">transporter</span> from Neisseria meningitidis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saleem, Muhammad; Prince, Stephen M; Patel, Hema; Chan, Hannah; Feavers, Ian M; Derrick, Jeremy P</p> <p>2012-02-01</p> <p>FrpB is an integral outer membrane protein from the human pathogen Neisseria meningitidis. It is a member of the TonB-dependent <span class="hlt">transporter</span> family and promotes the uptake of <span class="hlt">iron</span> across the outer membrane. There is also evidence that FrpB is an antigen and hence a potential component of a vaccine against meningococcal meningitis. FrpB incorporating a polyhistidine tag was overexpressed in Escherichia coli into inclusion bodies. The protein was then solubilized in urea, refolded and purified to homogeneity. Two separate antigenic variants of FrpB were crystallized by sitting-drop vapour diffusion. Crystals of the F5-1 variant diffracted to 2.4 Å resolution and belonged to space group C2, with unit-cell parameters a = 176.5, b = 79.4, c = 75.9 Å, β = 98.3°. Crystal-packing calculations suggested the presence of a monomer in the asymmetric unit. Crystals of the F3-3 variant also diffracted to 2.4 Å resolution and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 85.3, b = 104.6, c = 269.1 Å. Preliminary analysis suggested the presence of an FrpB trimer in the asymmetric unit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20163828','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20163828"><span id="translatedtitle">Characteristics of two types of stabilized nano zero-valent <span class="hlt">iron</span> and <span class="hlt">transport</span> in porous media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, Yu-Hao; Tseng, Hui-Hsin; Wey, Ming-Yen; Lin, Min-Der</p> <p>2010-04-15</p> <p>Nano-scale zero-valent <span class="hlt">iron</span> (NZVI) has been shown to be suitable for remediating contaminated aquifers. However, they usually aggregate rapidly and result in a very limited migration distance that inhibits their usefulness. This study employed poly acrylic acid (PAA) and carboxymethyl cellulose (CMC) to synthesize two types of stabilized styles of NZVI with finer sizes (namely PNZVI and CNZVI). The mobility of stabilized NZVI was also demonstrated on the basis of <span class="hlt">transport</span> in porous media. The results show that the PNZVI has a uniform particle size of 12 nm. However, tens of CNZVI particles with diameters of 1-3 nm were packed into secondary particles. Both the PNZVI and the CNZVI exhibited amorphous structures, and the stabilizer was bound to particle surfaces in the form of bidentate bridging via the carboxylic group, which could provide both electrostatic and steric repulsion to prevent particle aggregation. This study also proposes presumed stabilized configurations of PNZVI and CNZVI to reasonably illustrate their different dispersed suspension types. On the basis of the breakthrough curves and mass recovery, this study observed that the mobility of PNZVI in classic Ca(2+) concentration of groundwater was superior to CNZVI. Nonetheless, the mobility of CNZVI would be decreased less significantly than PNZVI when encountering high Ca(2+) concentrations (40 mM). Presumably, increasing the pore flow velocity would enhance the mobility of stabilized NZVI. Overall, the results of this study indicate that PNZVI has the potential to become an effective reactive material for in situ groundwater remediation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25820385','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25820385"><span id="translatedtitle">An update on the <span class="hlt">transport</span> and metabolism of <span class="hlt">iron</span> in Listeria monocytogenes: the role of proteins involved in pathogenicity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lechowicz, Justyna; Krawczyk-Balska, Agata</p> <p>2015-08-01</p> <p>Listeria monocytogenes is a Gram-positive bacterium that causes a rare but severe human disease with high mortality rate. The microorganism is widespread in the natural environment where it shows a saprophytic lifestyle. In the human body it infects many different cell types, where it lives intracellularly, however it may also temporarily live extracellularly. The ability to survive and grow in such diverse niches suggests that this bacterium has a wide range of mechanisms for both the acquisition of various sources of <span class="hlt">iron</span> and effective management of this microelement. In this review, data about the mechanisms of <span class="hlt">transport</span>, metabolism and regulation of <span class="hlt">iron</span>, including recent findings in these areas, are summarized with focus on the importance of these mechanisms for the virulence of L. monocytogenes. These data indicate the key role of haem <span class="hlt">transport</span> and maintenance of intracellular <span class="hlt">iron</span> homeostasis for the pathogenesis of L. monocytogenes. Furthermore, some of the proteins involved in <span class="hlt">iron</span> homeostasis like Fri and FrvA seem to deserve special attention due to their potential use in the development of new therapeutic antilisterial strategies. PMID:25820385</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4624760','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4624760"><span id="translatedtitle">Deficiency of Calcium-Independent Phospholipase A2 Beta Induces Brain <span class="hlt">Iron</span> Accumulation through Upregulation of Divalent Metal <span class="hlt">Transporter</span> 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Beck, Goichi; Shinzawa, Koei; Hayakawa, Hideki; Baba, Kousuke; Yasuda, Toru; Sumi-Akamaru, Hisae; Tsujimoto, Yoshihide; Mochizuki, Hideki</p> <p>2015-01-01</p> <p>Mutations in PLA2G6 have been proposed to be the cause of neurodegeneration with brain <span class="hlt">iron</span> accumulation type 2. The present study aimed to clarify the mechanism underlying brain <span class="hlt">iron</span> accumulation during the deficiency of calcium-independent phospholipase A2 beta (iPLA2β), which is encoded by the PLA2G6 gene. Perl’s staining with diaminobenzidine enhancement was used to visualize brain <span class="hlt">iron</span> accumulation. Western blotting was used to investigate the expression of molecules involved in <span class="hlt">iron</span> homeostasis, including divalent metal <span class="hlt">transporter</span> 1 (DMT1) and <span class="hlt">iron</span> regulatory proteins (IRP1 and 2), in the brains of iPLA2β-knockout (KO) mice as well as in PLA2G6-knockdown (KD) SH-SY5Y human neuroblastoma cells. Furthermore, mitochondrial functions such as ATP production were examined. We have discovered for the first time that marked <span class="hlt">iron</span> deposition was observed in the brains of iPLA2β-KO mice since the early clinical stages. DMT1 and IRP2 were markedly upregulated in all examined brain regions of aged iPLA2β-KO mice compared to age-matched wild-type control mice. Moreover, peroxidized lipids were increased in the brains of iPLA2β-KO mice. DMT1 and IRPs were significantly upregulated in PLA2G6-KD cells compared with cells treated with negative control siRNA. Degeneration of the mitochondrial inner membrane and decrease of ATP production were observed in PLA2G6-KD cells. These results suggest that the genetic ablation of iPLA2β increased <span class="hlt">iron</span> uptake in the brain through the activation of IRP2 and upregulation of DMT1, which may be associated with mitochondrial dysfunction. PMID:26506412</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26506412','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26506412"><span id="translatedtitle">Deficiency of Calcium-Independent Phospholipase A2 Beta Induces Brain <span class="hlt">Iron</span> Accumulation through Upregulation of Divalent Metal <span class="hlt">Transporter</span> 1.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Beck, Goichi; Shinzawa, Koei; Hayakawa, Hideki; Baba, Kousuke; Yasuda, Toru; Sumi-Akamaru, Hisae; Tsujimoto, Yoshihide; Mochizuki, Hideki</p> <p>2015-01-01</p> <p>Mutations in PLA2G6 have been proposed to be the cause of neurodegeneration with brain <span class="hlt">iron</span> accumulation type 2. The present study aimed to clarify the mechanism underlying brain <span class="hlt">iron</span> accumulation during the deficiency of calcium-independent phospholipase A2 beta (iPLA2β), which is encoded by the PLA2G6 gene. Perl's staining with diaminobenzidine enhancement was used to visualize brain <span class="hlt">iron</span> accumulation. Western blotting was used to investigate the expression of molecules involved in <span class="hlt">iron</span> homeostasis, including divalent metal <span class="hlt">transporter</span> 1 (DMT1) and <span class="hlt">iron</span> regulatory proteins (IRP1 and 2), in the brains of iPLA2β-knockout (KO) mice as well as in PLA2G6-knockdown (KD) SH-SY5Y human neuroblastoma cells. Furthermore, mitochondrial functions such as ATP production were examined. We have discovered for the first time that marked <span class="hlt">iron</span> deposition was observed in the brains of iPLA2β-KO mice since the early clinical stages. DMT1 and IRP2 were markedly upregulated in all examined brain regions of aged iPLA2β-KO mice compared to age-matched wild-type control mice. Moreover, peroxidized lipids were increased in the brains of iPLA2β-KO mice. DMT1 and IRPs were significantly upregulated in PLA2G6-KD cells compared with cells treated with negative control siRNA. Degeneration of the mitochondrial inner membrane and decrease of ATP production were observed in PLA2G6-KD cells. These results suggest that the genetic ablation of iPLA2β increased <span class="hlt">iron</span> uptake in the brain through the activation of IRP2 and upregulation of DMT1, which may be associated with mitochondrial dysfunction. PMID:26506412</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020094349','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020094349"><span id="translatedtitle">The Integrated Air <span class="hlt">Transportation</span> <span class="hlt">System</span> Evaluation Tool</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wingrove, Earl R., III; Hees, Jing; Villani, James A.; Yackovetsky, Robert E. (Technical Monitor)</p> <p>2002-01-01</p> <p>Throughout U.S. history, our nation has generally enjoyed exceptional economic growth, driven in part by <span class="hlt">transportation</span> advancements. Looking forward 25 years, when the national highway and skyway <span class="hlt">systems</span> are saturated, the nation faces new challenges in creating <span class="hlt">transportation</span>-driven economic growth and wealth. To meet the national requirement for an improved air traffic management <span class="hlt">system</span>, NASA developed the goal of tripling throughput over the next 20 years, in all weather conditions while maintaining safety. Analysis of the throughput goal has primarily focused on major airline operations, primarily through the hub and spoke <span class="hlt">system</span>.However, many suggested concepts to increase throughput may operate outside the hub and spoke <span class="hlt">system</span>. Examples of such concepts include the Small Aircraft <span class="hlt">Transportation</span> <span class="hlt">System</span>, civil tiltrotor, and improved rotorcraft. Proper assessment of the potential contribution of these technologies to the domestic air <span class="hlt">transportation</span> <span class="hlt">system</span> requires a modeling capability that includes the country's numerous smaller airports, acting as a fundamental component of the National Air space <span class="hlt">System</span>, and the demand for such concepts and technologies. Under this task for NASA, the Logistics Management Institute developed higher fidelity demand models that capture the interdependence of short-haul air travel with other <span class="hlt">transportation</span> modes and explicitly consider the costs of commercial air and other <span class="hlt">transport</span> modes. To accomplish this work, we generated forecasts of the distribution of general aviation based aircraft and GA itinerant operations at each of nearly 3.000 airport based on changes in economic conditions and demographic trends. We also built modules that estimate the demand for travel by different modes, particularly auto, commercial air, and GA. We examined GA demand from two perspectives: top-down and bottom-up, described in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070012359','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070012359"><span id="translatedtitle">A Robust Scalable <span class="hlt">Transportation</span> <span class="hlt">System</span> Concept</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hahn, Andrew; DeLaurentis, Daniel</p> <p>2006-01-01</p> <p>This report documents the 2005 Revolutionary <span class="hlt">System</span> Concept for Aeronautics (RSCA) study entitled "A Robust, Scalable <span class="hlt">Transportation</span> <span class="hlt">System</span> Concept". The objective of the study was to generate, at a high-level of abstraction, characteristics of a new concept for the National Airspace <span class="hlt">System</span>, or the new NAS, under which <span class="hlt">transportation</span> goals such as increased throughput, delay reduction, and improved robustness could be realized. Since such an objective can be overwhelmingly complex if pursued at the lowest levels of detail, instead a <span class="hlt">System-of-Systems</span> (SoS) approach was adopted to model alternative air <span class="hlt">transportation</span> architectures at a high level. The SoS approach allows the consideration of not only the technical aspects of the NAS", but also incorporates policy, socio-economic, and alternative <span class="hlt">transportation</span> <span class="hlt">system</span> considerations into one architecture. While the representations of the individual <span class="hlt">systems</span> are basic, the higher level approach allows for ways to optimize the SoS at the network level, determining the best topology (i.e. configuration of nodes and links). The final product (concept) is a set of rules of behavior and network structure that not only satisfies national <span class="hlt">transportation</span> goals, but represents the high impact rules that accomplish those goals by getting the agents to "do the right thing" naturally. The novel combination of Agent Based Modeling and Network Theory provides the core analysis methodology in the <span class="hlt">System-of-Systems</span> approach. Our method of approach is non-deterministic which means, fundamentally, it asks and answers different questions than deterministic models. The nondeterministic method is necessary primarily due to our marriage of human <span class="hlt">systems</span> with technological ones in a partially unknown set of future worlds. Our goal is to understand and simulate how the SoS, human and technological components combined, evolve.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21177266','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21177266"><span id="translatedtitle">Disorders of <span class="hlt">iron</span> metabolism. Part 1: molecular basis of <span class="hlt">iron</span> homoeostasis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Muñoz, Manuel; García-Erce, José Antonio; Remacha, Angel Francisco</p> <p>2011-04-01</p> <p><span class="hlt">IRON</span> FUNCTIONS: <span class="hlt">Iron</span> is an essential micronutrient, as it is required for satisfactory erythropoietic function, oxidative metabolism and cellular immune response. <span class="hlt">IRON</span> PHYSIOLOGY: Absorption of dietary <span class="hlt">iron</span> (1-2 mg/day) is tightly regulated and just balanced against <span class="hlt">iron</span> loss because there are no active <span class="hlt">iron</span> excretory mechanisms. Dietary <span class="hlt">iron</span> is found in haem (10%) and non-haem (ionic, 90%) forms, and their absorption occurs at the apical surface of duodenal enterocytes via different mechanisms. <span class="hlt">Iron</span> is exported by ferroportin 1 (the only putative <span class="hlt">iron</span> exporter) across the basolateral membrane of the enterocyte into the circulation (absorbed <span class="hlt">iron</span>), where it binds to transferrin and is <span class="hlt">transported</span> to sites of use and storage. Transferrin-bound <span class="hlt">iron</span> enters target cells-mainly erythroid cells, but also immune and hepatic cells-via receptor-mediated endocytosis. Senescent erythrocytes are phagocytosed by reticuloendothelial <span class="hlt">system</span> macrophages, haem is metabolised by haem oxygenase, and the released <span class="hlt">iron</span> is stored as ferritin. <span class="hlt">Iron</span> will be later exported from macrophages to transferrin. This internal turnover of <span class="hlt">iron</span> is essential to meet the requirements of erythropoiesis (20-30 mg/day). As transferrin becomes saturated in <span class="hlt">iron</span>-overload states, excess <span class="hlt">iron</span> is <span class="hlt">transported</span> to the liver, the other main storage organ for <span class="hlt">iron</span>, carrying the risk of free radical formation and tissue damage. REGULATION OF <span class="hlt">IRON</span> HOMOEOSTASIS: Hepcidin, synthesised by hepatocytes in response to <span class="hlt">iron</span> concentrations, inflammation, hypoxia and erythropoiesis, is the main <span class="hlt">iron</span>-regulatory hormone. It binds ferroportin on enterocytes, macrophages and hepatocytes triggering its internalisation and lysosomal degradation. Inappropriate hepcidin secretion may lead to either <span class="hlt">iron</span> deficiency or <span class="hlt">iron</span> overload.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JCHyd.182...51C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JCHyd.182...51C"><span id="translatedtitle">Magnetic resonance imaging reveals detailed spatial and temporal distribution of <span class="hlt">iron</span>-based nanoparticles <span class="hlt">transported</span> through water-saturated porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuny, Laure; Herrling, Maria Pia; Guthausen, Gisela; Horn, Harald; Delay, Markus</p> <p>2015-11-01</p> <p>The application of engineered nanoparticles (ENP) such as <span class="hlt">iron</span>-based ENP in environmental <span class="hlt">systems</span> or in the human body inevitably raises the question of their mobility. This also includes aspects of product optimization and assessment of their environmental fate. Therefore, the key aim was to investigate the mobility of <span class="hlt">iron</span>-based ENP in water-saturated porous media. Laboratory-scale <span class="hlt">transport</span> experiments were conducted using columns packed with quartz sand as model solid phase. Different superparamagnetic <span class="hlt">iron</span> oxide nanoparticles (SPION) were selected to study the influence of primary particle size (dP = 20 nm and 80 nm) and surface functionalization (plain, -COOH and -NH2 groups) on particle mobility. In particular, the influence of natural organic matter (NOM) on the <span class="hlt">transport</span> and retention behaviour of SPION was investigated. In our approach, a combination of conventional breakthrough curve (BTC) analysis and magnetic resonance imaging (MRI) to non-invasively and non-destructively visualize the SPION inside the column was applied. Particle surface properties (surface functionalization and resulting zeta potential) had a major influence while their primary particle size turned out to be less relevant. In particular, the mobility of SPION was significantly increased in the presence of NOM due to the sorption of NOM onto the particle surface resulting in a more negative zeta potential. MRI provided detailed spatially resolved information complementary to the quantitative BTC results. The approach can be transferred to other porous <span class="hlt">systems</span> and contributes to a better understanding of particle <span class="hlt">transport</span> in environmental porous media and porous media in technical applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26335945','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26335945"><span id="translatedtitle">Magnetic resonance imaging reveals detailed spatial and temporal distribution of <span class="hlt">iron</span>-based nanoparticles <span class="hlt">transported</span> through water-saturated porous media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cuny, Laure; Herrling, Maria Pia; Guthausen, Gisela; Horn, Harald; Delay, Markus</p> <p>2015-11-01</p> <p>The application of engineered nanoparticles (ENP) such as <span class="hlt">iron</span>-based ENP in environmental <span class="hlt">systems</span> or in the human body inevitably raises the question of their mobility. This also includes aspects of product optimization and assessment of their environmental fate. Therefore, the key aim was to investigate the mobility of <span class="hlt">iron</span>-based ENP in water-saturated porous media. Laboratory-scale <span class="hlt">transport</span> experiments were conducted using columns packed with quartz sand as model solid phase. Different superparamagnetic <span class="hlt">iron</span> oxide nanoparticles (SPION) were selected to study the influence of primary particle size (d(P)=20 nm and 80 nm) and surface functionalization (plain, -COOH and -NH2 groups) on particle mobility. In particular, the influence of natural organic matter (NOM) on the <span class="hlt">transport</span> and retention behaviour of SPION was investigated. In our approach, a combination of conventional breakthrough curve (BTC) analysis and magnetic resonance imaging (MRI) to non-invasively and non-destructively visualize the SPION inside the column was applied. Particle surface properties (surface functionalization and resulting zeta potential) had a major influence while their primary particle size turned out to be less relevant. In particular, the mobility of SPION was significantly increased in the presence of NOM due to the sorption of NOM onto the particle surface resulting in a more negative zeta potential. MRI provided detailed spatially resolved information complementary to the quantitative BTC results. The approach can be transferred to other porous <span class="hlt">systems</span> and contributes to a better understanding of particle <span class="hlt">transport</span> in environmental porous media and porous media in technical applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6704A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6704A"><span id="translatedtitle">Aquifer Thermal Energy Storage as an ecosystem service for Brussels, Belgium: investigating <span class="hlt">iron</span> (hydr)oxide precipitation with reactive <span class="hlt">transport</span> modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anibas, Christian; Possemiers, Mathias; Huysmans, Marijke</p> <p>2016-04-01</p> <p>In an evolving energy <span class="hlt">system</span> it is important that urbanized areas contribute to their own energy demands. To reduce greenhouse gas emissions sustainable energy <span class="hlt">systems</span> with a high efficiency are required, e.g. using urban aquifers as an ecosystem service. Here the potential of seasonal aquifer thermal energy storage and recovery (ATES) for the Brussels-Capital Region, Belgium is investigated. An important shallow geologic formation in the Brussels Capital Region is the Brussels Sand formation, a 20-60 m thick phreatic aquifer. The Brussels Sand Formation is known for its potential for ATES <span class="hlt">systems</span>, but also for its varying redox and hydraulic conditions. Important limiting factors for ATES <span class="hlt">systems</span> in the Brussels Sand Formation therefore are the hydraulic conductivity and the geochemical composition of the groundwater. Near the redox boundary <span class="hlt">iron</span> hydroxide precipitation can negatively influence ATES well performance due to clogging. The interactions between physical processes (e.g. particle <span class="hlt">transport</span> and clogging in the wider proximity of the ATES well) and chemical processes (e.g. influence of the operation temperatures on precipitation processes) during ATES operation are complex but not well understood. Therefore we constructed numerical groundwater flow models in MODFLOW to estimate maximum pumping and injection rates of different hydraulic conditions and competing water uses in the Brussels Sand Formation. In further steps the thermal potential for ATES was quantified using MT3DMS and the reactive <span class="hlt">transport</span> model PHT3D was applied to assess the effects of operating ATES <span class="hlt">systems</span> near the redox boundary. Results show that initial mixing plays an important role in the development of <span class="hlt">iron</span>(hydr)oxide precipitation around the ATES wells, with the highest concentrations around the cold wells. This behavior is enhanced by the temperature effect; temperature differences of ΔT≈10°C already influence the <span class="hlt">iron</span> (hydr)oxide concentration. The initial injection into the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26934982','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26934982"><span id="translatedtitle">Structural model of FeoB, the <span class="hlt">iron</span> <span class="hlt">transporter</span> from Pseudomonas aeruginosa, predicts a cysteine lined, GTP-gated pore.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Seyedmohammad, Saeed; Fuentealba, Natalia Alveal; Marriott, Robert A J; Goetze, Tom A; Edwardson, J Michael; Barrera, Nelson P; Venter, Henrietta</p> <p>2016-01-01</p> <p><span class="hlt">Iron</span> is essential for the survival and virulence of pathogenic bacteria. The FeoB <span class="hlt">transporter</span> allows the bacterial cell to acquire ferrous <span class="hlt">iron</span> from its environment, making it an excellent drug target in intractable pathogens. The protein consists of an N-terminal GTP-binding domain and a C-terminal membrane domain. Despite the availability of X-ray crystal structures of the N-terminal domain, many aspects of the structure and function of FeoB remain unclear, such as the structure of the membrane domain, the oligomeric state of the protein, the molecular mechanism of <span class="hlt">iron</span> <span class="hlt">transport</span>, and how this is coupled to GTP hydrolysis at the N-terminal domain. In the present study, we describe the first homology model of FeoB. Due to the lack of sequence homology between FeoB and other <span class="hlt">transporters</span>, the structures of four different proteins were used as templates to generate the homology model of full-length FeoB, which predicts a trimeric structure. We confirmed this trimeric structure by both blue-native-PAGE (BN-PAGE) and AFM. According to our model, the membrane domain of the trimeric protein forms a central pore lined by highly conserved cysteine residues. This pore aligns with a central pore in the N-terminal GTPase domain (G-domain) lined by aspartate residues. Biochemical analysis of FeoB from Pseudomonas aeruginosa further reveals a putative <span class="hlt">iron</span> sensor domain that could connect GTP binding/hydrolysis to the opening of the pore. These results indicate that FeoB might not act as a <span class="hlt">transporter</span>, but rather as a GTP-gated channel.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4847171','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4847171"><span id="translatedtitle">Structural model of FeoB, the <span class="hlt">iron</span> <span class="hlt">transporter</span> from Pseudomonas aeruginosa, predicts a cysteine lined, GTP-gated pore</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Seyedmohammad, Saeed; Fuentealba, Natalia Alveal; Marriott, Robert A.J.; Goetze, Tom A.; Edwardson, J. Michael; Barrera, Nelson P.; Venter, Henrietta</p> <p>2016-01-01</p> <p><span class="hlt">Iron</span> is essential for the survival and virulence of pathogenic bacteria. The FeoB <span class="hlt">transporter</span> allows the bacterial cell to acquire ferrous <span class="hlt">iron</span> from its environment, making it an excellent drug target in intractable pathogens. The protein consists of an N-terminal GTP-binding domain and a C-terminal membrane domain. Despite the availability of X-ray crystal structures of the N-terminal domain, many aspects of the structure and function of FeoB remain unclear, such as the structure of the membrane domain, the oligomeric state of the protein, the molecular mechanism of <span class="hlt">iron</span> <span class="hlt">transport</span>, and how this is coupled to GTP hydrolysis at the N-terminal domain. In the present study, we describe the first homology model of FeoB. Due to the lack of sequence homology between FeoB and other <span class="hlt">transporters</span>, the structures of four different proteins were used as templates to generate the homology model of full-length FeoB, which predicts a trimeric structure. We confirmed this trimeric structure by both blue-native-PAGE (BN-PAGE) and AFM. According to our model, the membrane domain of the trimeric protein forms a central pore lined by highly conserved cysteine residues. This pore aligns with a central pore in the N-terminal GTPase domain (G-domain) lined by aspartate residues. Biochemical analysis of FeoB from Pseudomonas aeruginosa further reveals a putative <span class="hlt">iron</span> sensor domain that could connect GTP binding/hydrolysis to the opening of the pore. These results indicate that FeoB might not act as a <span class="hlt">transporter</span>, but rather as a GTP-gated channel. PMID:26934982</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22316080','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22316080"><span id="translatedtitle">Humic acid facilitates the <span class="hlt">transport</span> of ARS-labeled hydroxyapatite nanoparticles in <span class="hlt">iron</span> oxyhydroxide-coated sand.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Dengjun; Bradford, Scott A; Harvey, Ronald W; Gao, Bin; Cang, Long; Zhou, Dongmei</p> <p>2012-03-01</p> <p>Hydroxyapatite nanoparticles (nHAP) have been widely used to remediate soil and wastewater contaminated with metals and radionuclides. However, our understanding of nHAP <span class="hlt">transport</span> and fate is limited in natural environments that exhibit significant variability in solid and solution chemistry. The <span class="hlt">transport</span> and retention kinetics of Alizarin red S (ARS)-labeled nHAP were investigated in water-saturated packed columns that encompassed a range of humic acid concentrations (HA, 0-10 mg L(-1)), fractional surface coverage of <span class="hlt">iron</span> oxyhydroxide coatings on sand grains (λ, 0-0.75), and pH (6.0-10.5). HA was found to have a marked effect on the electrokinetic properties of ARS-nHAP, and on the <span class="hlt">transport</span> and retention of ARS-nHAP in granular media. The <span class="hlt">transport</span> of ARS-nHAP was found to increase with increasing HA concentration because of enhanced colloidal stability and the reduced aggregate size. When HA = 10 mg L(-1), greater ARS-nHAP attachment occurred with increasing λ because of increased electrostatic attraction between negatively charged nanoparticles and positively charged <span class="hlt">iron</span> oxyhydroxides, although alkaline conditions (pH 8.0 and 10.5) reversed the surface charge of the <span class="hlt">iron</span> oxyhydroxides and therefore decreased deposition. The retention profiles of ARS-nHAP exhibited a hyperexponential shape for all test conditions, suggesting some unfavorable attachment conditions. Retarded breakthrough curves occurred in sands with <span class="hlt">iron</span> oxyhydroxide coatings because of time-dependent occupation of favorable deposition sites. Consideration of the above effects is necessary to improve remediation efficiency of nHAP for metals and actinides in soils and subsurface environments. PMID:22316080</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26287170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26287170"><span id="translatedtitle">Route and Regulation of Zinc, Cadmium, and <span class="hlt">Iron</span> <span class="hlt">Transport</span> in Rice Plants (Oryza sativa L.) during Vegetative Growth and Grain Filling: Metal <span class="hlt">Transporters</span>, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yoneyama, Tadakatsu; Ishikawa, Satoru; Fujimaki, Shu</p> <p>2015-08-13</p> <p>Zinc (Zn) and <span class="hlt">iron</span> (Fe) are essential but are sometimes deficient in humans, while cadmium (Cd) is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal <span class="hlt">transport</span> and accumulation in rice plants by examining metal speciation, metal <span class="hlt">transporters</span>, and the xylem-to-phloem <span class="hlt">transport</span> <span class="hlt">system</span>. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem <span class="hlt">transport</span> <span class="hlt">system</span> operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2'-deoxymugineic acid) are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake <span class="hlt">transporter</span> and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot <span class="hlt">transport</span>, respectively, resulting in a reduction of grain Cd accumulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4581289','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4581289"><span id="translatedtitle">Route and Regulation of Zinc, Cadmium, and <span class="hlt">Iron</span> <span class="hlt">Transport</span> in Rice Plants (Oryza sativa L.) during Vegetative Growth and Grain Filling: Metal <span class="hlt">Transporters</span>, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yoneyama, Tadakatsu; Ishikawa, Satoru; Fujimaki, Shu</p> <p>2015-01-01</p> <p>Zinc (Zn) and <span class="hlt">iron</span> (Fe) are essential but are sometimes deficient in humans, while cadmium (Cd) is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal <span class="hlt">transport</span> and accumulation in rice plants by examining metal speciation, metal <span class="hlt">transporters</span>, and the xylem-to-phloem <span class="hlt">transport</span> <span class="hlt">system</span>. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem <span class="hlt">transport</span> <span class="hlt">system</span> operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2′-deoxymugineic acid) are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake <span class="hlt">transporter</span> and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot <span class="hlt">transport</span>, respectively, resulting in a reduction of grain Cd accumulation. PMID:26287170</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4167583','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4167583"><span id="translatedtitle">Superparamagnetic <span class="hlt">Iron</span> Oxide Nanoparticle-Based Delivery <span class="hlt">Systems</span> for Biotherapeutics</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mok, Hyejung; Zhang, Miqin</p> <p>2014-01-01</p> <p>Introduction Superparamagnetic <span class="hlt">iron</span> oxide nanoparticle (SPION)-based carrier <span class="hlt">systems</span> have many advantages over other nanoparticle-based <span class="hlt">systems</span>. They are biocompatible, biodegradable, facilely tunable, and superparamagnetic and thus controllable by an external magnetic field. These attributes enable their broad biomedical applications. In particular, magnetically-driven carriers are drawing considerable interest as an emerging therapeutic delivery <span class="hlt">system</span> because of their superior delivery efficiency. Area covered This article reviews the recent advances in use of SPION-based carrier <span class="hlt">systems</span> to improve the delivery efficiency and target specificity of biotherapeutics. We examine various formulations of SPION-based delivery <span class="hlt">systems</span>, including SPION micelles, clusters, hydrogels, liposomes, and micro/nanospheres, as well as their specific applications in delivery of biotherapeutics. Expert opinion Recently, biotherapeutics including therapeutic cells, proteins and genes have been studied as alternative treatments to various diseases. Despite the advantages of high target specificity and low adverse effects, clinical translation of biotherapeutics has been hindered by the poor stability and low delivery efficiency compared to chemical drugs. Accordingly, biotherapeutic delivery <span class="hlt">systems</span> that can overcome these limitations are actively pursued. SPION-based materials can be ideal candidates for developing such delivery <span class="hlt">systems</span> because of their excellent biocompatibility and superparamagnetism that enables long-term accumulation/retention at target sites by utilization of a suitable magnet. In addition, synthesis technologies for production of finely-tuned, homogeneous SPIONs have been well developed, which may promise their rapid clinical translation. PMID:23199200</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830024244','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830024244"><span id="translatedtitle">Acoustic <span class="hlt">system</span> for material <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barmatz, M. B.; Trinh, E. H.; Wang, T. G.; Elleman, D. D.; Jacobi, N. (Inventor)</p> <p>1983-01-01</p> <p>An object within a chamber is acoustically moved by applying wavelengths of different modes to the chamber to move the object between pressure wells formed by the modes. In one <span class="hlt">system</span>, the object is placed in one end of the chamber while a resonant mode, applied along the length of the chamber, produces a pressure well at the location. The frequency is then switched to a second mode that produces a pressure well at the center of the chamber, to draw the object. When the object reaches the second pressure well and is still traveling towards the second end of the chamber, the acoustic frequency is again shifted to a third mode (which may equal the first model) that has a pressure well in the second end portion of the chamber, to draw the object. A heat source may be located near the second end of the chamber to heat the sample, and after the sample is heated it can be cooled by moving it in a corresponding manner back to the first end of the chamber. The transducers for levitating and moving the object may be all located at the cool first end of the chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/792016','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/792016"><span id="translatedtitle">The Secure, <span class="hlt">Transportable</span>, Autonomous Reactor <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brown, N.W.; Hassberger, J.A.; Smith, C.; Carelli, M.; Greenspan, E.; Peddicord, K.L.; Stroh, K.; Wade, D.C.; Hill, R.N.</p> <p>1999-05-27</p> <p>The Secure, <span class="hlt">Transportable</span>, Autonomous Reactor (STAR) <span class="hlt">system</span> is a development architecture for implementing a small nuclear power <span class="hlt">system</span>, specifically aimed at meeting the growing energy needs of much of the developing world. It simultaneously provides very high standards for safety, proliferation resistance, ease and economy of installation, operation, and ultimate disposition. The STAR <span class="hlt">system</span> accomplishes these objectives through a combination of modular design, factory manufacture, long lifetime without refueling, autonomous control, and high reliability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1413491B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1413491B"><span id="translatedtitle">Carbon supported Nano-<span class="hlt">Iron</span> for environmental remediation: <span class="hlt">Transport</span> observations using column tests, magnet resonance imaging and synchrotron tomography.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Busch, J.; Oswald, S. E.; Mackenzie, K.</p> <p>2012-04-01</p> <p>The use of nano-zerovalent <span class="hlt">iron</span> (nZVI) for environmental remediation is a promising new technique for in situ remediation of contaminated groundwater. Due to its high surface area and high reactivity, nZVI is able to dechlorinate organic contaminants and render them harmless. Limited mobility, however, due to fast aggregation and sedimentation of nZVI, restricts the practical applicability for source and plume remediation. Carbo-<span class="hlt">Iron</span> is a newly developed composite material consisting of activated carbon particles (d50 about 500 nm) that act as carrier for nZVI particles. Together with a polyanionic stabilizer (CMC) Carbo-<span class="hlt">Iron</span> is able to form a stable injectable suspension. These particles are designed to combine the mobility of activated carbon and the reactivity of nZVI. Various methods were used to observe and describe <span class="hlt">transport</span> properties, with a focus on column tests and tomographic methods: Column tests were performed in chromatography columns of 40 and 60 cm length, filled with sand grains or glass beads. Results indicate high mobility and breakthrough after addition of CMC, but changing <span class="hlt">transport</span> properties at different pH and ionic strength. Magnet Resonance Imaging (MRI) and Synchrotron Imaging are technologies of growing interest in observing flow and <span class="hlt">transport</span> in porous media. Even though both methods are based on different physical principles, both are sensible to <span class="hlt">iron</span> loads in colloids and allow two- and three-dimensional reconstruction and visualization. Therefore both methods may principally be suitable for observing Carbo-<span class="hlt">Iron</span> in porous media and might give information complementary to other experimental investigations. A suitable MRI method was developed using a medical MRI. The method based on T1 weighted measurement with short repetition time (TR = 7.0 ms) and echo time (TE = 2.95 ms) can detect different particle concentrations in a porous medium. The synchrotron tomography method used an energy rich (13 keV) parallel X-ray beam to collect</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=246665','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=246665"><span id="translatedtitle">Nitrate <span class="hlt">Transport</span> <span class="hlt">System</span> in Neurospora crassa</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schloemer, Robert H.; Garrett, Reginald H.</p> <p>1974-01-01</p> <p>Nitrate uptake in Neurospora crassa has been investigated under various conditions of nitrogen nutrition by measuring the rate of disappearance of nitrate from the medium and by determining mycelial nitrate accumulation. The nitrate <span class="hlt">transport</span> <span class="hlt">system</span> is induced by either nitrate or nitrite, but is not present in mycelia grown on ammonia or Casamino Acids. The appearance of nitrate uptake activity is prevented by cycloheximide, puromycin, or 6-methyl purine. The induced nitrate <span class="hlt">transport</span> <span class="hlt">system</span> displays a Km for nitrate of 0.25 mM. Nitrate uptake is inhibited by metabolic poisons such as 2,4-dinitrophenol, cyanide, and antimycin A. Furthermore, mycelia can concentrate nitrate 50-fold. Ammonia and nitrite are non-competitive inhibitors with respect to nitrate, with Ki values of 0.13 and 0.17 mM, respectively. Ammonia does not repress the formation of the nitrate <span class="hlt">transport</span> <span class="hlt">system</span>. In contrast, the nitrate uptake <span class="hlt">system</span> is repressed by Casamino Acids. All amino acids individually prevent nitrate accumulation, with the exception of methionine, glutamine, and alanine. The influence of nitrate reduction and the nitrate reductase protein on nitrate <span class="hlt">transport</span> was investigated in wild-type Neurospora lacking a functional nitrate reductase and in nitrate non-utilizing mutants, nit-1, nit-2, and nit-3. These mycelia contain an inducible nitrate <span class="hlt">transport</span> <span class="hlt">system</span> which displays the same characteristics as those found in the wild-type mycelia having the functional nitrate reductase. These findings suggest that nitrate <span class="hlt">transport</span> is not dependent upon nitrate reduction and that these two processes are separate events in the assimilation of nitrate. PMID:4274457</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900007819','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900007819"><span id="translatedtitle">A Mars/phobos <span class="hlt">Transportation</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1989-01-01</p> <p>A <span class="hlt">transportation</span> <span class="hlt">system</span> will be necessary to support construction and operation of bases on Phobos and Mars beginning in the year 2020 or later. An approach to defining a network of vehicles and the types of vehicles which may be used in the <span class="hlt">system</span> are presented. The network will provide a convenient, integrated means for <span class="hlt">transporting</span> robotically constructed bases to Phobos and Mars. All the technology needed for the current plan is expected to be available for use at the projected date of cargo departure from the Earth <span class="hlt">system</span>. The modular design of the <span class="hlt">transportation</span> <span class="hlt">system</span> provides easily implemented contingency plans, so that difficulties with any one vehicle will have a minimal effect on the progress of the total mission. The <span class="hlt">transportation</span> network proposed consists of orbital vehicles and atmospheric entry vehicles. Initially, only orbital vehicles will participate in the robotic construction phase of the Phobos base. The Interplanetary Transfer Vehicle (ITV) will carry the base and construction equipment to Phobos where the Orbital Maneuvering Vehicles (OMV's) will participate in the initial construction of the base. When the Mars base is ready to be sent, one or more ITV's will be used to <span class="hlt">transport</span> the atmospheric entry vehicles from Earth. These atmospheric vehicles are the One Way Landers (OWL's) and the Ascent/Descent Vehicles (ADV's). They will be used to carry the base components and/or construction equipment. The OMV's and the Orbital Transfer Vehicles (OTV's) will assist in carrying the atmospheric entry vehicles to low Martian orbit where the OWL's or ADV's will descent to the planet surface. The ADV's were proposed to accommodate expansion of the <span class="hlt">system</span>. Additionally, a smaller version of the ADV class is capable of <span class="hlt">transporting</span> personnel between Mars and Phobos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25223225','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25223225"><span id="translatedtitle">Influence of welding fume on <span class="hlt">systemic</span> <span class="hlt">iron</span> status.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Casjens, Swaantje; Henry, Jana; Rihs, Hans-Peter; Lehnert, Martin; Raulf-Heimsoth, Monika; Welge, Peter; Lotz, Anne; Gelder, Rainer Van; Hahn, Jens-Uwe; Stiegler, Hugo; Eisele, Lewin; Weiss, Tobias; Hartwig, Andrea; Brüning, Thomas; Pesch, Beate</p> <p>2014-11-01</p> <p><span class="hlt">Iron</span> is the major metal found in welding fumes, and although it is an essential trace element, its overload causes toxicity due to Fenton reactions. To avoid oxidative damage, excess <span class="hlt">iron</span> is bound to ferritin, and as a result, serum ferritin (SF) is a recognized biomarker for <span class="hlt">iron</span> stores, with high concentrations linked to inflammation and potentially also cancer. However, little is known about <span class="hlt">iron</span> overload in welders. Within this study, we assessed the <span class="hlt">iron</span> status and quantitative associations between airborne <span class="hlt">iron</span>, body <span class="hlt">iron</span> stores, and <span class="hlt">iron</span> homeostasis in 192 welders not wearing dust masks. Welders were equipped with personal samplers in order to determine the levels of respirable <span class="hlt">iron</span> in the breathing zone during a working shift. SF, prohepcidin and other markers of <span class="hlt">iron</span> status were determined in blood samples collected after shift. The impact of <span class="hlt">iron</span> exposure and other factors on SF and prohepcidin were estimated using multiple regression models. Our results indicate that respirable <span class="hlt">iron</span> is a significant predictor of SF and prohepcidin. Concentrations of SF varied according to the welding technique and respiratory protection used, with a median of 103 μg l(-1) in tungsten inert gas welders, 125 μg l(-1) in those wearing air-purifying respirators, and 161 μg l(-1) in other welders. Compared to welders with low <span class="hlt">iron</span> stores (SF < 25 μg l(-1)), those with excess body <span class="hlt">iron</span> (SF ≥ 400 μg l(-1)) worked under a higher median concentration of airborne <span class="hlt">iron</span> (60 μg m(-3) versus 148 μg m(-3)). Even though air concentrations of respirable <span class="hlt">iron</span> and manganese were highly correlated, and low <span class="hlt">iron</span> stores have been reported to increase manganese uptake in the gastrointestinal tract, no correlation was seen between SF and manganese in blood. In conclusion, monitoring SF may be a reasonable method for health surveillance of welders. Respiratory protection with air-purifying respirators can decrease <span class="hlt">iron</span> exposure and avoid chronically higher SF in welders working with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25223225','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25223225"><span id="translatedtitle">Influence of welding fume on <span class="hlt">systemic</span> <span class="hlt">iron</span> status.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Casjens, Swaantje; Henry, Jana; Rihs, Hans-Peter; Lehnert, Martin; Raulf-Heimsoth, Monika; Welge, Peter; Lotz, Anne; Gelder, Rainer Van; Hahn, Jens-Uwe; Stiegler, Hugo; Eisele, Lewin; Weiss, Tobias; Hartwig, Andrea; Brüning, Thomas; Pesch, Beate</p> <p>2014-11-01</p> <p><span class="hlt">Iron</span> is the major metal found in welding fumes, and although it is an essential trace element, its overload causes toxicity due to Fenton reactions. To avoid oxidative damage, excess <span class="hlt">iron</span> is bound to ferritin, and as a result, serum ferritin (SF) is a recognized biomarker for <span class="hlt">iron</span> stores, with high concentrations linked to inflammation and potentially also cancer. However, little is known about <span class="hlt">iron</span> overload in welders. Within this study, we assessed the <span class="hlt">iron</span> status and quantitative associations between airborne <span class="hlt">iron</span>, body <span class="hlt">iron</span> stores, and <span class="hlt">iron</span> homeostasis in 192 welders not wearing dust masks. Welders were equipped with personal samplers in order to determine the levels of respirable <span class="hlt">iron</span> in the breathing zone during a working shift. SF, prohepcidin and other markers of <span class="hlt">iron</span> status were determined in blood samples collected after shift. The impact of <span class="hlt">iron</span> exposure and other factors on SF and prohepcidin were estimated using multiple regression models. Our results indicate that respirable <span class="hlt">iron</span> is a significant predictor of SF and prohepcidin. Concentrations of SF varied according to the welding technique and respiratory protection used, with a median of 103 μg l(-1) in tungsten inert gas welders, 125 μg l(-1) in those wearing air-purifying respirators, and 161 μg l(-1) in other welders. Compared to welders with low <span class="hlt">iron</span> stores (SF < 25 μg l(-1)), those with excess body <span class="hlt">iron</span> (SF ≥ 400 μg l(-1)) worked under a higher median concentration of airborne <span class="hlt">iron</span> (60 μg m(-3) versus 148 μg m(-3)). Even though air concentrations of respirable <span class="hlt">iron</span> and manganese were highly correlated, and low <span class="hlt">iron</span> stores have been reported to increase manganese uptake in the gastrointestinal tract, no correlation was seen between SF and manganese in blood. In conclusion, monitoring SF may be a reasonable method for health surveillance of welders. Respiratory protection with air-purifying respirators can decrease <span class="hlt">iron</span> exposure and avoid chronically higher SF in welders working with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022162','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022162"><span id="translatedtitle">Bacteriophage PRD1 and silica colloid <span class="hlt">transport</span> and recovery in an <span class="hlt">iron</span> oxide-coated sand aquifer</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ryan, J.N.; Elimelech, M.; Ard, R.A.; Harvey, R.W.; Johnson, P.R.</p> <p>1999-01-01</p> <p>Bacteriophage PRD1 and silica colloids were co-injected into sewage- contaminated and uncontaminated zones of an <span class="hlt">iron</span> oxide-coated sand aquifer on Cape Cod, MA, and their <span class="hlt">transport</span> was monitored over distances up to 6 m in three arrays. After deposition, the attached PRD1 and silica colloids were mobilized by three different chemical perturbations (elevated pH, anionic surfactant, and reductant). PRD1 and silica colloids experienced less attenuation in the contaminated zone where adsorbed organic matter and phosphate may be hindering attachment of PRD1 and silica colloids to the <span class="hlt">iron</span> oxide coatings. The PRD1 collision efficiencies agree well with collision efficiencies predicted by assuming favorable PRD1 deposition on <span class="hlt">iron</span> oxide coatings for which the surface area coverage was measured by microprobe analysis of sediment thin sections. ?? potentials of the PRD1, silica colloids, and aquifer grains corroborated the <span class="hlt">transport</span> results, indicating that electrostatic forces dominated the attachment of PRD1 and silica colloids. Elevated pH was the chemical perturbation most effective at mobilizing the attached PRD1 and silica colloids. Elevated surfactant concentration mobilized the attached PRD1 and silica colloids more effectively in the contaminated zone than in the uncontaminated zone.Bacteriophage PRD1 and silica colloids were co-injected into sewage-contaminated and uncontaminated zones of an <span class="hlt">iron</span> oxide-coated sand aquifer on Cape Cod, MA, and their <span class="hlt">transport</span> was monitored over distances up to 6 m in three arrays. After deposition, the attached PRD1 and silica colloids were mobilized by three different chemical perturbations (elevated pH, anionic surfactant, and reductant). PRD1 and silica colloids experienced less attenuation in the contaminated zone where adsorbed organic matter and phosphate may be hindering attachment of PRD1 and silica colloids to the <span class="hlt">iron</span> oxide coatings. The PRD1 collision efficiencies agree well with collision efficiencies predicted by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22416861','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22416861"><span id="translatedtitle">Splicing factor SR34b mutation reduces cadmium tolerance in Arabidopsis by regulating <span class="hlt">iron</span>-regulated <span class="hlt">transporter</span> 1 gene</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Wentao; Du, Bojing; Liu, Di; Qi, Xiaoting</p> <p>2014-12-12</p> <p>Highlights: • Arabidopsis splicing factor SR34b gene is cadmium-inducible. • SR34b T-DNA insertion mutant is sensitive to cadmium due to high cadmium uptake. • SR34b is a regulator of cadmium <span class="hlt">transporter</span> IRT1 at the posttranscription level. • These results highlight the roles of splicing factors in cadmium tolerance of plant. - Abstract: Serine/arginine-rich (SR) proteins are important splicing factors. However, the biological functions of plant SR proteins remain unclear especially in abiotic stresses. Cadmium (Cd) is a non-essential element that negatively affects plant growth and development. In this study, we provided clear evidence for SR gene involved in Cd tolerance in planta. <span class="hlt">Systemic</span> expression analysis of 17 Arabidopsis SR genes revealed that SR34b is the only SR gene upregulated by Cd, suggesting its potential roles in Arabidopsis Cd tolerance. Consistent with this, a SR34b T-DNA insertion mutant (sr34b) was moderately sensitive to Cd, which had higher Cd{sup 2+} uptake rate and accumulated Cd in greater amounts than wild-type. This was due to the altered expression of <span class="hlt">iron</span>-regulated <span class="hlt">transporter</span> 1 (IRT1) gene in sr34b mutant. Under normal growth conditions, IRT1 mRNAs highly accumulated in sr34b mutant, which was a result of increased stability of IRT1 mRNA. Under Cd stress, however, sr34b mutant plants had a splicing defect in IRT1 gene, thus reducing the IRT1 mRNA accumulation. Despite of this, sr34b mutant plants still constitutively expressed IRT1 proteins under Cd stress, thereby resulting in Cd stress-sensitive phenotype. We therefore propose the essential roles of SR34b in posttranscriptional regulation of IRT1 expression and identify it as a regulator of Arabidopsis Cd tolerance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992gdc..rept......','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992gdc..rept......"><span id="translatedtitle"><span class="hlt">Transportation</span> <span class="hlt">systems</span> analyses. Volume 1: Executive summary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>1992-11-01</p> <p>The principal objective is to accomplish a <span class="hlt">systems</span> engineering assessment of the nation's space <span class="hlt">transportation</span> infrastructure. This analysis addresses the necessary elements to perform crew delivery and return, cargo transfer, cargo delivery and return, payload servicing, and the exploration of the Moon and Mars. Specific elements analyzed, but not limited to, include: the Space Exploration Initiative (SEI), the National Launch <span class="hlt">System</span> (NLS), the current expendable launch vehicle (ELV) fleet, ground facilities, the Space Station Freedom (SSF), and other civil, military and commercial payloads. The performance of this study entails maintaining a broad perspective on the large number of <span class="hlt">transportation</span> elements that could potentially comprise the U.S. space infrastructure over the next several decades. To perform this <span class="hlt">systems</span> evaluation, top-level trade studies are conducted to enhance our understanding of the relationship between elements of the infrastructure. This broad 'infrastructure-level perspective' permits the identification of preferred infrastructures. Sensitivity analyses are performed to assure the credibility and usefulness of study results. Conceptual studies of <span class="hlt">transportation</span> elements contribute to the <span class="hlt">systems</span> approach by identifying elements (such as ETO node and transfer/excursion vehicles) needed in current and planned <span class="hlt">transportation</span> <span class="hlt">systems</span>. These studies are also a mechanism to integrate the results of relevant parallel studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25662508','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25662508"><span id="translatedtitle">Blood withdrawal affects <span class="hlt">iron</span> store dynamics in primates with consequences on monoaminergic <span class="hlt">system</span> function.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hyacinthe, C; De Deurwaerdere, P; Thiollier, T; Li, Q; Bezard, E; Ghorayeb, I</p> <p>2015-04-01</p> <p><span class="hlt">Iron</span> homeostasis is essential for the integrity of brain monoaminergic functions and its deregulation might be involved in neurological movement disorders such as the restless legs syndrome (RLS). Although <span class="hlt">iron</span> metabolism breakdown concomitantly appears with monoaminergic <span class="hlt">system</span> dysfunction in <span class="hlt">iron</span>-deficient rodents and in RLS patients, the direct consequences of peripheral <span class="hlt">iron</span> deficiency in the central nervous <span class="hlt">system</span> (CNS) of non-human primates have received little attention. Here, we evaluated the peripheral <span class="hlt">iron</span>-depletion impact on brain monoamine levels in macaque monkeys. After documenting circadian variations of <span class="hlt">iron</span> and <span class="hlt">iron</span>-related proteins (hemoglobin, ferritin and transferrin) in both serum and cerebrospinal fluid (CSF) of normal macaques, repeated blood withdrawals (RBW) were used to reduce peripheral <span class="hlt">iron</span>-related parameter levels. Decreased serum <span class="hlt">iron</span> levels were paradoxically associated with increased CSF <span class="hlt">iron</span> concentrations. Despite limited consequences on tissue monoamine contents (dopamine - DA, 3, 4-dihydroxyphenylacetic acid - DOPAC, homovanillic acid, L-3, 4-dihydroxyphenylalanine - L-DOPA, 5-8 hydroxytryptamine - 5-HT, 5-hydroxyindoleacetic acid - 5-HIAA and noradrenaline) measured with post-mortem chromatography, we found distinct and region-dependent relationships of these tissue concentrations with CSF <span class="hlt">iron</span> and/or serum <span class="hlt">iron</span> and/or blood hemoglobin. Additionally, striatal extracellular DA, DOPAC and 5-HIAA levels evaluated by in vivo microdialysis showed a substantial increase, suggesting an overall increase in both DA and 5-HT tones. Finally, a trending increase in general locomotor activity, measured by actimetry, was observed in the most serum <span class="hlt">iron</span>-depleted macaques. Taken together, our data are compatible with an increase in nigrostriatal DAergic function in the event of <span class="hlt">iron</span> deficiency and point to a specific alteration of the 5-HT/DA interaction in the CNS that is possibly involved in the etiology of RLS. PMID:25662508</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150018900','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150018900"><span id="translatedtitle">Crew <span class="hlt">Transportation</span> <span class="hlt">System</span> Design Reference Missions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mango, Edward J.</p> <p>2015-01-01</p> <p>Contains summaries of potential design reference mission goals for <span class="hlt">systems</span> to <span class="hlt">transport</span> humans to andfrom low Earth orbit (LEO) for the Commercial Crew Program. The purpose of this document is to describe Design Reference Missions (DRMs) representative of the end-to-end Crew <span class="hlt">Transportation</span> <span class="hlt">System</span> (CTS) framework envisioned to successfully execute commercial crew <span class="hlt">transportation</span> to orbital destinations. The initial CTS architecture will likely be optimized to support NASA crew and NASA-sponsored crew rotation missions to the ISS, but consideration may be given in this design phase to allow for modifications in order to accomplish other commercial missions in the future. With the exception of NASA’s mission to the ISS, the remaining commercial DRMs are notional. Any decision to design or scar the CTS for these additional non-NASA missions is completely up to the Commercial Provider. As NASA’s mission needs evolve over time, this document will be periodically updated to reflect those needs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1176112','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1176112"><span id="translatedtitle">Ion <span class="hlt">transport</span> membrane module and vessel <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Stein, VanEric Edward; Carolan, Michael Francis; Chen, Christopher M.; Armstrong, Phillip Andrew; Wahle, Harold W.; Ohrn, Theodore R.; Kneidel, Kurt E.; Rackers, Keith Gerard; Blake, James Erik; Nataraj, Shankar; van Doorn, Rene Hendrik Elias; Wilson, Merrill Anderson</p> <p>2007-02-20</p> <p>An ion <span class="hlt">transport</span> membrane <span class="hlt">system</span> comprising (a) a pressure vessel having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion <span class="hlt">transport</span> membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; and (c) one or more gas manifolds in flow communication with interior regions of the membrane modules and with the exterior of the pressure vessel. The ion <span class="hlt">transport</span> membrane <span class="hlt">system</span> may be utilized in a gas separation device to recover oxygen from an oxygen-containing gas or as an oxidation reactor to oxidize compounds in a feed gas stream by oxygen permeated through the mixed metal oxide ceramic material of the membrane modules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/983067','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/983067"><span id="translatedtitle">Ion <span class="hlt">transport</span> membrane module and vessel <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Stein, VanEric Edward; Carolan, Michael Francis; Chen, Christopher M.; Armstrong, Phillip Andrew; Wahle, Harold W.; Ohrn, Theodore R.; Kneidel, Kurt E.; Rackers, Keith Gerard; Blake, James Erik; Nataraj, Shankar; van Doorn, Rene Hendrik Elias; Wilson, Merrill Anderson</p> <p>2008-02-26</p> <p>An ion <span class="hlt">transport</span> membrane <span class="hlt">system</span> comprising (a) a pressure vessel having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion <span class="hlt">transport</span> membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; and (c) one or more gas manifolds in flow communication with interior regions of the membrane modules and with the exterior of the pressure vessel.The ion <span class="hlt">transport</span> membrane <span class="hlt">system</span> may be utilized in a gas separation device to recover oxygen from an oxygen-containing gas or as an oxidation reactor to oxidize compounds in a feed gas stream by oxygen permeated through the mixed metal oxide ceramic material of the membrane modules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1037001','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1037001"><span id="translatedtitle">Ion <span class="hlt">transport</span> membrane module and vessel <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Stein, VanEric Edward; Carolan, Michael Francis; Chen, Christopher M.; Armstrong, Phillip Andrew; Wahle, Harold W.; Ohrn, Theodore R.; Kneidel, Kurt E.; Rackers, Keith Gerard; Blake, James Erik; Nataraj, Shankar; Van Doorn, Rene Hendrik Elias; Wilson, Merrill Anderson</p> <p>2012-02-14</p> <p>An ion <span class="hlt">transport</span> membrane <span class="hlt">system</span> comprising (a) a pressure vessel having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion <span class="hlt">transport</span> membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; and (c) one or more gas manifolds in flow communication with interior regions of the membrane modules and with the exterior of the pressure vessel. The ion <span class="hlt">transport</span> membrane <span class="hlt">system</span> may be utilized in a gas separation device to recover oxygen from an oxygen-containing gas or as an oxidation reactor to oxidize compounds in a feed gas stream by oxygen permeated through the mixed metal oxide ceramic material of the membrane modules.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=209944','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=209944"><span id="translatedtitle">Nucleotide sequences of the fecBCDE genes and locations of the proteins suggest a periplasmic-binding-protein-dependent <span class="hlt">transport</span> mechanism for <span class="hlt">iron</span>(III) dicitrate in Escherichia coli.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Staudenmaier, H; Van Hove, B; Yaraghi, Z; Braun, V</p> <p>1989-01-01</p> <p>The fec region of the Escherichia coli chromosome determines a citrate-dependent <span class="hlt">iron</span>(III) <span class="hlt">transport</span> <span class="hlt">system</span>. The nucleotide sequence of fec revealed five genes, fecABCDE, which are transcribed from fecA to fecE. The fecA gene encodes a previously described outer membrane receptor protein. The fecB gene product is formed as a precursor protein with a signal peptide of 21 amino acids; the mature form, with a molecular weight of 30,815, was previously found in the periplasm. The fecB genes of E. coli B and E. coli K-12 differed in 3 nucleotides, of which 2 gave rise to conservative amino acid exchanges. The fecC and fecD genes were found to encode very hydrophobic polypeptides with molecular weights of 35,367 and 34,148, respectively, both of which are localized in the cytoplasmic membrane. The fecE product was a rather hydrophilic but cytoplasmic membrane-bound protein of Mr 28,189 and contained regions of extensive homology to ATP-binding proteins. The number, structural characteristics, and locations of the FecBCDE proteins were typical for a periplasmic-binding-protein-dependent <span class="hlt">transport</span> <span class="hlt">system</span>. It is proposed that after FecA- and TonB-dependent <span class="hlt">transport</span> of <span class="hlt">iron</span>(III) dicitrate across the outer membrane, uptake through the cytoplasmic membrane follows the binding-protein-dependent <span class="hlt">transport</span> mechanism. FecC and FecD exhibited homologies to each other, to the N- and C-terminal halves of FhuB of the <span class="hlt">iron</span>(III) hydroxamate <span class="hlt">transport</span> <span class="hlt">system</span>, and to BtuC of the vitamin B12 <span class="hlt">transport</span> <span class="hlt">system</span>. FecB showed some homology to FhuD, suggesting that the latter may function in the same manner as a binding protein in <span class="hlt">iron</span>(III) hydroxamate <span class="hlt">transport</span>. The close homology between the proteins of the two <span class="hlt">iron</span> <span class="hlt">transport</span> <span class="hlt">systems</span> and of the vitamin B12 <span class="hlt">transport</span> <span class="hlt">system</span> indicates a common evolution for all three <span class="hlt">systems</span>. Images PMID:2651410</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AIPC.1655e0003D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPC.1655e0003D"><span id="translatedtitle">Low energy beam <span class="hlt">transport</span> <span class="hlt">system</span> developments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.</p> <p>2015-04-01</p> <p>For high brightness beam production it is important to preserve the brightness in the low energy beam <span class="hlt">transport</span> <span class="hlt">system</span> (LEBT) used to <span class="hlt">transport</span> and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam <span class="hlt">transport</span>, reliable electrostatic LEBT operation has been demonstrated with H- beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam <span class="hlt">transport</span>. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H- beams, but such gas densities cause unacceptably high H- beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for <span class="hlt">transport</span> of high current H- beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable <span class="hlt">transport</span> of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27433157','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27433157"><span id="translatedtitle">A Putative Mitochondrial <span class="hlt">Iron</span> <span class="hlt">Transporter</span> MrsA in Aspergillus fumigatus Plays Important Roles in Azole-, Oxidative Stress Responses and Virulence.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Long, Nanbiao; Xu, Xiaoling; Qian, Hui; Zhang, Shizhu; Lu, Ling</p> <p>2016-01-01</p> <p><span class="hlt">Iron</span> is an essential nutrient and enzyme co-factor required for a wide range of cellular processes, especially for the function of mitochondria. For the opportunistic fungal pathogen Aspergillus fumigatus, the ability to obtain <span class="hlt">iron</span> is required for growth and virulence during the infection process. However, knowledge of how mitochondria are involved in <span class="hlt">iron</span> regulation is still limited. Here, we show that a mitochondrial <span class="hlt">iron</span> <span class="hlt">transporter</span>, MrsA, a homolog of yeast Mrs4p, is critical for adaptation to <span class="hlt">iron</span>-limited or <span class="hlt">iron</span>-excess conditions in A. fumigatus. Deletion of mrsA leads to disruption of <span class="hlt">iron</span> homeostasis with a decreased sreA expression, resulted in activated reductive <span class="hlt">iron</span> assimilation (RIA) and siderophore-mediated <span class="hlt">iron</span> acquisition (SIA). Furthermore, deletion of mrsA induces hypersusceptibility to azole and oxidative stresses. An assay for cellular ROS content in ΔmrsA combined with rescue from the mrsA-defective phenotype by the antioxidant reagent L-ascorbic acid indicates that the increased sensitivity of ΔmrsA to the azole itraconazole and to oxidative stress is mainly the result of abnormal ROS accumulation. Moreover, site-directed mutation experiments verified that three conserved histidine residues related to <span class="hlt">iron</span> <span class="hlt">transport</span> in MrsA are required for responses to oxidative and azole stresses. Importantly, ΔmrsA causes significant attenuation of virulence in an immunocompromised murine model of aspergillosis. Collectively, our results show that the putative mitochondrial <span class="hlt">iron</span> <span class="hlt">transporter</span> MrsA plays important roles in azole- and oxidative-stress responses and virulence by regulating the balance of cellular <span class="hlt">iron</span> in A. fumigatus. PMID:27433157</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4922219','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4922219"><span id="translatedtitle">A Putative Mitochondrial <span class="hlt">Iron</span> <span class="hlt">Transporter</span> MrsA in Aspergillus fumigatus Plays Important Roles in Azole-, Oxidative Stress Responses and Virulence</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Long, Nanbiao; Xu, Xiaoling; Qian, Hui; Zhang, Shizhu; Lu, Ling</p> <p>2016-01-01</p> <p><span class="hlt">Iron</span> is an essential nutrient and enzyme co-factor required for a wide range of cellular processes, especially for the function of mitochondria. For the opportunistic fungal pathogen Aspergillus fumigatus, the ability to obtain <span class="hlt">iron</span> is required for growth and virulence during the infection process. However, knowledge of how mitochondria are involved in <span class="hlt">iron</span> regulation is still limited. Here, we show that a mitochondrial <span class="hlt">iron</span> <span class="hlt">transporter</span>, MrsA, a homolog of yeast Mrs4p, is critical for adaptation to <span class="hlt">iron</span>-limited or <span class="hlt">iron</span>-excess conditions in A. fumigatus. Deletion of mrsA leads to disruption of <span class="hlt">iron</span> homeostasis with a decreased sreA expression, resulted in activated reductive <span class="hlt">iron</span> assimilation (RIA) and siderophore-mediated <span class="hlt">iron</span> acquisition (SIA). Furthermore, deletion of mrsA induces hypersusceptibility to azole and oxidative stresses. An assay for cellular ROS content in ΔmrsA combined with rescue from the mrsA-defective phenotype by the antioxidant reagent L-ascorbic acid indicates that the increased sensitivity of ΔmrsA to the azole itraconazole and to oxidative stress is mainly the result of abnormal ROS accumulation. Moreover, site-directed mutation experiments verified that three conserved histidine residues related to <span class="hlt">iron</span> <span class="hlt">transport</span> in MrsA are required for responses to oxidative and azole stresses. Importantly, ΔmrsA causes significant attenuation of virulence in an immunocompromised murine model of aspergillosis. Collectively, our results show that the putative mitochondrial <span class="hlt">iron</span> <span class="hlt">transporter</span> MrsA plays important roles in azole- and oxidative-stress responses and virulence by regulating the balance of cellular <span class="hlt">iron</span> in A. fumigatus. PMID:27433157</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/866233','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/866233"><span id="translatedtitle">Heat <span class="hlt">transport</span> <span class="hlt">system</span>, method and material</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Musinski, Donald L.</p> <p>1987-01-01</p> <p>A heat <span class="hlt">transport</span> <span class="hlt">system</span>, method and composite material in which a plurality of hollow spherical shells or microspheres having an outside diameter of less than or equal to 500 microns are encapsulated or embedded within a bulk material. Each shell has captured therein a volatile working fluid, such that each shell operates as a microsized heat pipe for conducting heat through the composite structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993STIN...9410826.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993STIN...9410826."><span id="translatedtitle"><span class="hlt">Transportation</span> <span class="hlt">systems</span> analyses: Volume 1: Executive Summary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>1993-05-01</p> <p>The principal objective of this study is to accomplish a <span class="hlt">systems</span> engineering assessment of the nation's space <span class="hlt">transportation</span> infrastructure. This analysis addresses the necessary elements to perform man delivery and return, cargo transfer, cargo delivery, payload servicing, and the exploration of the Moon and Mars. Specific elements analyzed, but not limited to, include the Space Exploration Initiative (SEI), the National Launch <span class="hlt">System</span> (NLS), the current expendable launch vehicle (ELV) fleet, ground facilities, the Space Station Freedom (SSF), and other civil, military and commercial payloads. The performance of this study entails maintaining a broad perspective on the large number of <span class="hlt">transportation</span> elements that could potentially comprise the U.S. space infrastructure over the next several decades. To perform this <span class="hlt">systems</span> evaluation, top-level trade studies are conducted to enhance our understanding of the relationships between elements of the infrastructure. This broad 'infrastructure-level perspective' permits the identification of preferred infrastructures. Sensitivity analyses are performed to assure the credibility and usefulness of study results. This executive summary of the <span class="hlt">transportation</span> <span class="hlt">systems</span> analyses (TSM) semi-annual report addresses the SSF logistics resupply. Our analysis parallels the ongoing NASA SSF redesign effort. Therefore, there could be no SSF design to drive our logistics analysis. Consequently, the analysis attempted to bound the reasonable SSF design possibilities (and the subsequent <span class="hlt">transportation</span> implications). No other strategy really exists until after a final decision is rendered on the SSF configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024885','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024885"><span id="translatedtitle"><span class="hlt">Transport</span> and cycling of <span class="hlt">iron</span> and hydrogen peroxide in a freshwater stream: Influence of organic acids</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Scott, D.T.; Runkel, R.L.; McKnight, Diane M.; Voelker, B.M.; Kimball, B.A.; Carraway, E.R.</p> <p>2003-01-01</p> <p>An in-stream injection of two dissolved organic acids (phthalic and aspartic acids) was performed in an acidic mountain stream to assess the effects of organic acids on Fe photoreduction and H2O2 cycling. Results indicate that the fate of Fe is dependent on a net balance of oxidative and reductive processes, which can vary over a distance of several meters due to changes in incident light and other factors. Solution phase photoreduction rates were high in sunlit reaches and were enhanced by the organic acid addition but were also limited by the amount of ferric <span class="hlt">iron</span> present in the water column. Fe oxide photoreduction from the streambed and colloids within the water column resulted in an increase in the diurnal load of total filterable Fe within the experimental reach, which also responded to increases in light and organic acids. Our results also suggest that Fe(II) oxidation increased in response to the organic acids, with the result of offsetting the increase in Fe(II) from photoreductive processes. Fe(II) was rapidly oxidized to Fe(III) after sunset and during the day within a well-shaded reach, presumably through microbial oxidation. H2O 2, a product of dissolved organic matter photolysis, increased downstream to maximum concentrations of 0.25 ??M midday. Kinetic calculations show that the buildup of H2O2 is controlled by reaction with Fe(III), but this has only a small effect on Fe(II) because of the small formation rates of H2O2 compared to those of Fe(II). The results demonstrate the importance of incorporating the effects of light and dissolved organic carbon into Fe reactive <span class="hlt">transport</span> models to further our understanding of the fate of Fe in streams and lakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26685186','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26685186"><span id="translatedtitle">Knocking down mitochondrial <span class="hlt">iron</span> <span class="hlt">transporter</span> (MIT) reprograms primary and secondary metabolism in rice plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vigani, Gianpiero; Bashir, Khurram; Ishimaru, Yasuhiro; Lehmann, Martin; Casiraghi, Fabio Marco; Nakanishi, Hiromi; Seki, Motoaki; Geigenberger, Peter; Zocchi, Graziano; Nishizawa, Naoko K</p> <p>2016-03-01</p> <p><span class="hlt">Iron</span> (Fe) is an essential micronutrient for plant growth and development, and its reduced bioavailability strongly impairs mitochondrial functionality. In this work, the metabolic adjustment in the rice (Oryza sativa) mitochondrial Fe <span class="hlt">transporter</span> knockdown mutant (mit-2) was analysed. Biochemical characterization of purified mitochondria from rice roots showed alteration in the respiratory chain of mit-2 compared with wild-type (WT) plants. In particular, proteins belonging to the type II alternative NAD(P)H dehydrogenases accumulated strongly in mit-2 plants, indicating that alternative pathways were activated to keep the respiratory chain working. Additionally, large-scale changes in the transcriptome and metabolome were observed in mit-2 rice plants. In particular, a strong alteration (up-/down-regulation) in the expression of genes encoding enzymes of both primary and secondary metabolism was found in mutant plants. This was reflected by changes in the metabolic profiles in both roots and shoots of mit-2 plants. Significant alterations in the levels of amino acids belonging to the aspartic acid-related pathways (aspartic acid, lysine, and threonine in roots, and aspartic acid and ornithine in shoots) were found that are strictly connected to the Krebs cycle. Furthermore, some metabolites (e.g. pyruvic acid, fumaric acid, ornithine, and oligosaccharides of the raffinose family) accumulated only in the shoot of mit-2 plants, indicating possible hypoxic responses. These findings suggest that the induction of local Fe deficiency in the mitochondrial compartment of mit-2 plants differentially affects the transcript as well as the metabolic profiles in root and shoot tissues. PMID:26685186</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760011112','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760011112"><span id="translatedtitle">Future space <span class="hlt">transportation</span> <span class="hlt">systems</span> analysis study. Phase 1 extension: <span class="hlt">Transportation</span> <span class="hlt">systems</span> reference data, volume 2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1975-01-01</p> <p><span class="hlt">Transportation</span> mass requirements are developed for various mission and <span class="hlt">transportation</span> modes based on vehicle <span class="hlt">systems</span> sized to fit the exact needs of each mission. The parametric data used to derive the mass requirements for each mission and <span class="hlt">transportation</span> mode are presented to enable accommodation of possible changes in mode options or payload definitions. The vehicle sizing and functional requirements used to derive the parametric data are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=244370','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=244370"><span id="translatedtitle">Elevated <span class="hlt">systemic</span> hepcidin and <span class="hlt">iron</span> depletion in obese pre-menopausal females.</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Hepcidin, the body’s main regulator of <span class="hlt">systemic</span> <span class="hlt">iron</span> homeostasis, is unregulated in response to inflammation, and is thought to play a role in the manifestation of <span class="hlt">iron</span> deficiency (ID) observed in obese populations. We determined <span class="hlt">systemic</span> hepcidin levels and its association with body mass, inflammat...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=162704&keyword=iron+AND+hydroxides&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=79627999&CFTOKEN=65629921','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=162704&keyword=iron+AND+hydroxides&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=79627999&CFTOKEN=65629921"><span id="translatedtitle"><span class="hlt">IRON</span> TUBERCULATION: PHYSIO-CHEMICAL CHARACTERIZATION OF A SINGLE PIPE FROM A DRINKING WATER DISTRIBUTION <span class="hlt">SYSTEM</span></span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The nature of <span class="hlt">iron</span> tubercles inside unlined <span class="hlt">iron</span> pipes of drinking water distribution <span class="hlt">systems</span> are influenced by water quality and therefore susceptible to changes in water chemistry. The underlying assumption is that tubercles in a <span class="hlt">system</span> have similar physio-chemical properties. ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5043597','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5043597"><span id="translatedtitle">Enhanced Histochemical Detection of <span class="hlt">Iron</span> in Paraffin Sections of Mouse Central Nervous <span class="hlt">System</span> Tissue</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sands, Scott A.; Leung-Toung, Regis; Wang, Yingsheng; Connelly, John</p> <p>2016-01-01</p> <p>Histochemical methods of detecting <span class="hlt">iron</span> in the rodent brain result mainly in the labeling of oligodendrocytes, but as all cells utilize <span class="hlt">iron</span>, this observation suggests that much of the <span class="hlt">iron</span> in the central nervous <span class="hlt">system</span> goes undetected. Paraffin embedding of tissue is a standard procedure that is used to prepare sections for microscopic analysis. In the present study, we questioned whether we could modify the <span class="hlt">iron</span> histochemical procedure to enable a greater detection of <span class="hlt">iron</span> in paraffin sections. Indeed, various modifications led to the widespread labeling of <span class="hlt">iron</span> in mouse brain tissue (for instance, labeling of neurons and neuropil). Sites of focal concentrations, such as cytoplasmic punctate or nucleolar staining, were also observed. The modified procedures were applied to paraffin sections of a mouse model (APP/PS1) of Alzheimer’s disease. <span class="hlt">Iron</span> was revealed in the plaque core and rim. The plaque rim had a fibrillary or granular appearance, and it frequently contained <span class="hlt">iron</span>-labeled cells. Further analysis indicated that the <span class="hlt">iron</span> was tightly associated with the core of the plaque, but less so with the rim. In conclusion, modifications to the histochemical staining revealed new insights into the deposition of <span class="hlt">iron</span> in the central nervous <span class="hlt">system</span>. In theory, the approach should be transferrable to organs besides the brain and to other species, and the underlying principles should be incorporable into a variety of staining methods. PMID:27683879</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15105251','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15105251"><span id="translatedtitle"><span class="hlt">Iron</span> metabolism and the IRE/IRP regulatory <span class="hlt">system</span>: an update.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pantopoulos, Kostas</p> <p>2004-03-01</p> <p>Cellular <span class="hlt">iron</span> homeostasis is accomplished by the coordinated regulated expression of the transferrin receptor and ferritin, which mediate <span class="hlt">iron</span> uptake and storage, respectively. The mechanism is posttranscriptional and involves two cytoplasmic <span class="hlt">iron</span> regulatory proteins, IRP1 and IRP2. Under conditions of <span class="hlt">iron</span> starvation, IRPs stabilize the transferrin receptor and inhibit the translation of ferritin mRNAs by binding to "<span class="hlt">iron</span> responsive elements" (IREs) within their untranslated regions. The IRE/IRP <span class="hlt">system</span> also controls the expression of additional IRE-containing mRNAs, encoding proteins of <span class="hlt">iron</span> and energy metabolism. The activities of IRP1 and IRP2 are regulated by distinct posttranslational mechanisms in response to cellular <span class="hlt">iron</span> levels. Thus, in <span class="hlt">iron</span>-replete cells, IRP1 assembles a cubane <span class="hlt">iron</span>-sulfur cluster, which prevents IRE binding, while IRP2 undergoes proteasomal degradation. IRP1 and IRP2 also respond, albeit differentially, to <span class="hlt">iron</span>-independent signals, such as hydrogen peroxide, hypoxia, or nitric oxide. Basic principles of the IRE/IRP <span class="hlt">system</span> and recent advances in understanding the regulation and the function of IRP1 and IRP2 are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5872707','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5872707"><span id="translatedtitle">Inactivation of transferrin <span class="hlt">iron</span> binding capacity by the neutrophil myeloperoxidase <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clark, R.A.; Pearson, D.W.</p> <p>1989-06-05</p> <p>Human serum apotransferrin was exposed to the isolated myeloperoxidase-H2O2-halide <span class="hlt">system</span> or to phorbol ester-activated human neutrophils. Such treatment resulted in a marked loss in transferrin <span class="hlt">iron</span> binding capacity as well as concomitant iodination of transferrin. Each component of the cell-free <span class="hlt">system</span> (myeloperoxidase, H2O2, iodide) or neutrophil <span class="hlt">system</span> (neutrophils, phorbol ester, iodide) was required in order to observe these changes. In the cell-free <span class="hlt">system</span>, the H2O2 requirement was fulfilled by either reagent H2O2 or the peroxide-generating <span class="hlt">system</span> glucose oxidase plus glucose. Both loss of <span class="hlt">iron</span> binding capacity and transferrin iodination by either the myeloperoxidase <span class="hlt">system</span> or activated neutrophils were blocked by azide or catalase. The isolated peroxidase <span class="hlt">system</span> had an acidic pH optimum, whereas the intact cell <span class="hlt">system</span> was more efficient at neutral pH. The kinetics of changes in <span class="hlt">iron</span> binding capacity and iodination closely paralleled one another, exhibiting t1/2 values of less than 1 min for the myeloperoxidase-H2O2 <span class="hlt">system</span>, 3-4 min for the myeloperoxidase-glucose oxidase <span class="hlt">system</span>, and 8 min for the neutrophil <span class="hlt">system</span>. That the occupied binding site is protected from the myeloperoxidase <span class="hlt">system</span> was suggested by (1) a failure to mobilize <span class="hlt">iron</span> from <span class="hlt">iron</span>-loaded transferrin, (2) an inverse correlation between initial <span class="hlt">iron</span> saturation and myeloperoxidase-mediated loss of <span class="hlt">iron</span> binding capacity, and (3) decreased myeloperoxidase-mediated iodination of <span class="hlt">iron</span>-loaded versus apotransferrin. Since as little as 1 atom of iodide bound per molecule of transferrin was associated with substantial losses in <span class="hlt">iron</span> binding capacity, there appears to be a high specificity of myeloperoxidase-catalyzed iodination for residues at or near the <span class="hlt">iron</span> binding sites. Amino acid analysis of iodinated transferrin (approximately 2 atoms/molecule) demonstrated that iodotyrosine was the predominant iodinated species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003909','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003909"><span id="translatedtitle">Space <span class="hlt">Transportation</span> <span class="hlt">System</span> (STS): Emergency support</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Janoski, T.; Nicholson, L.</p> <p>1991-01-01</p> <p>The DSN (Deep Space Network) mission support requirements for emergency support of the Space <span class="hlt">Transportation</span> <span class="hlt">System</span> (STS) are summarized. Coverage would be provided by the DSN during emergencies that would prevent communications between the shuttle and the White Sands TDRSS receiving station. The DSN support requirements are defined through the presentation of tables and narratives describing the spacecraft flight profile; DSN support coverage; frequency assignments; support parameters for telemetry, command and support <span class="hlt">systems</span>; and tracking support responsibility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25320851','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25320851"><span id="translatedtitle"><span class="hlt">Transport</span> characteristics of nanoscale zero-valent <span class="hlt">iron</span> carried by three different "vehicles" in porous media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Su, Yan; Zhao, Yong S; Li, Lu L; Qin, Chuan Y; Wu, Fan; Geng, Nan N; Lei, Jian S</p> <p>2014-01-01</p> <p>This study investigated the <span class="hlt">transport</span> properties of nanoscale zero-valent <span class="hlt">iron</span> (Fe(0)) (nZVI) carried by three vehicles: water, sodium dodecyl sulfate (SDS) solution, and SDS foam. Batch experiments were conducted to assess the sedimentation capability of nZVI particles in these three vehicles. Column experiments were conducted to investigate the <span class="hlt">transport</span> properties of nZVI in porous media formed with different sizes of sand (0.25 mm to 0.5 mm, 0.5 mm to 0.9 mm, and 0.9 mm to 1.4 mm). Three main results were obtained. First, the batch experiments revealed that the stabilities of nZVI particles in SDS solution and SDS foam were improved, compared with that of nZVI particles in water. Moreover, the sedimentation of nZVI in foam was closely associated with the foam drainage volume. The nZVI content in foam was similar to that in the original foaming suspension, and the nZVI particle distribution in foam became significantly more uniform at a stirring speed of 3000 r/min. Second, the <span class="hlt">transport</span> of nZVI was enhanced by foam compared with water and SDS solution for 0.25 mm to 0.5 mm diameter sand. For sand with diameters of 0.5 mm to 0.9 mm and 0.9 mm to 1.4 mm, the mobility of nZVI carried by SDS solution was optimal, followed by that of nZVI carried by foam and water. Thus, the mobility of nZVI in finer sand was significantly enhanced by foam, compared with that in coarse sand. In contrast, compared with the bare nZVI suspension and nZVI-laden foam, the spatial distribution of nZVI particles carried by SDS solution was significantly uniform along the column length. Third, the SDS concentration significantly influenced the migration of nZVI in porous media. The enhancement in the migration of nZVI carried by SDS solution was greater at an SDS dose of 0.25% compared with that at the other three doses (0.2%, 0.5%, and 1%) for sand with a 0.25 mm to 0.5 mm diameter. Increased SDS concentrations positively affected the <span class="hlt">transport</span> of nZVI by foam for sand with a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820021408&hterms=fires+uncontrolled&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfires%2Buncontrolled','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820021408&hterms=fires+uncontrolled&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfires%2Buncontrolled"><span id="translatedtitle">Fireworthiness of <span class="hlt">transport</span> aircraft interior <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, J. A.; Kourtides, D. A.</p> <p>1982-01-01</p> <p>The fire worthiness of air <span class="hlt">transport</span> interiors was evaluated. The effect of interior <span class="hlt">systems</span> on the survival of passengers and crew in an uncontrolled <span class="hlt">transport</span> aircraft fire is addressed. Modification of aircraft interior subsystem components which provide improvements in aircraft fire safety are examined. Three specific subsystem components, interior panels, seats and windows, offer the most immediate and highest payoff by modifying interior materials of existing aircrafts. It is shown that the new materials modifications reduce the fire hazards because of significant reduction in their characteristic flame spread, heat release, and smoke and toxic gas emissions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26220302','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26220302"><span id="translatedtitle">Performance of Nonmigratory <span class="hlt">Iron</span> Chelating Active Packaging Materials in Viscous Model Food <span class="hlt">Systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roman, Maxine J; Decker, Eric A; Goddard, Julie M</p> <p>2015-09-01</p> <p>Many packaged food products undergo quality deterioration due to <span class="hlt">iron</span> promoted oxidative reactions. Recently, we have developed a nonmigratory <span class="hlt">iron</span> chelating active packaging material that represents a novel approach to inhibit oxidation of foods while addressing consumer demands for "cleanˮ labels. A challenge to the field of nonmigratory active packaging is ensuring that surface-immobilized active agents retain activity in a true food <span class="hlt">system</span> despite diffusional limitations. Yet, the relationship between food viscosity and nonmigratory active packaging activity retention has never been characterized. The objective of this study was to investigate the influence of food viscosity on <span class="hlt">iron</span> chelation by a nonmigratory <span class="hlt">iron</span> chelating active packaging material. Methyl cellulose was added to aqueous buffered <span class="hlt">iron</span> solutions to yield model <span class="hlt">systems</span> with viscosities ranging from ∼1 to ∼10(5)  mPa·s, representing viscosities ranging from beverage to mayonnaise. <span class="hlt">Iron</span> chelation was quantified by material-bound <span class="hlt">iron</span> content using colorimetry and inductively coupled plasma-optical emission spectrometry (ICP-OES).  Maximum <span class="hlt">iron</span> chelation was reached in solutions up to viscosity ∼10(2)  mPa·s. In more viscous solutions (up to ∼10(4)  mPa·s), there was a significant decrease in <span class="hlt">iron</span> chelating capacity (P < 0.05). However, materials still retained at least 76% <span class="hlt">iron</span> chelating capacity. Additionally, the influence of different food hydrocolloids on the performance of nonmigratory <span class="hlt">iron</span> chelating active packaging was characterized. Methyl cellulose and carrageenan did not compete with the material for specific <span class="hlt">iron</span> chelation (P > 0.05). Materials retained 32% to 45% chelating capacity when in contact with competitively chelating hydrocolloids guar gum, locust bean gum, and xanthan gum. This work demonstrates the potential application of nonmigratory <span class="hlt">iron</span> chelating active packaging in liquid and semi-liquid foods to allow for the removal of synthetic chelators, while</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26220302','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26220302"><span id="translatedtitle">Performance of Nonmigratory <span class="hlt">Iron</span> Chelating Active Packaging Materials in Viscous Model Food <span class="hlt">Systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roman, Maxine J; Decker, Eric A; Goddard, Julie M</p> <p>2015-09-01</p> <p>Many packaged food products undergo quality deterioration due to <span class="hlt">iron</span> promoted oxidative reactions. Recently, we have developed a nonmigratory <span class="hlt">iron</span> chelating active packaging material that represents a novel approach to inhibit oxidation of foods while addressing consumer demands for "cleanˮ labels. A challenge to the field of nonmigratory active packaging is ensuring that surface-immobilized active agents retain activity in a true food <span class="hlt">system</span> despite diffusional limitations. Yet, the relationship between food viscosity and nonmigratory active packaging activity retention has never been characterized. The objective of this study was to investigate the influence of food viscosity on <span class="hlt">iron</span> chelation by a nonmigratory <span class="hlt">iron</span> chelating active packaging material. Methyl cellulose was added to aqueous buffered <span class="hlt">iron</span> solutions to yield model <span class="hlt">systems</span> with viscosities ranging from ∼1 to ∼10(5)  mPa·s, representing viscosities ranging from beverage to mayonnaise. <span class="hlt">Iron</span> chelation was quantified by material-bound <span class="hlt">iron</span> content using colorimetry and inductively coupled plasma-optical emission spectrometry (ICP-OES).  Maximum <span class="hlt">iron</span> chelation was reached in solutions up to viscosity ∼10(2)  mPa·s. In more viscous solutions (up to ∼10(4)  mPa·s), there was a significant decrease in <span class="hlt">iron</span> chelating capacity (P < 0.05). However, materials still retained at least 76% <span class="hlt">iron</span> chelating capacity. Additionally, the influence of different food hydrocolloids on the performance of nonmigratory <span class="hlt">iron</span> chelating active packaging was characterized. Methyl cellulose and carrageenan did not compete with the material for specific <span class="hlt">iron</span> chelation (P > 0.05). Materials retained 32% to 45% chelating capacity when in contact with competitively chelating hydrocolloids guar gum, locust bean gum, and xanthan gum. This work demonstrates the potential application of nonmigratory <span class="hlt">iron</span> chelating active packaging in liquid and semi-liquid foods to allow for the removal of synthetic chelators, while</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25788528','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25788528"><span id="translatedtitle">Hepcidin Mitigates Renal Ischemia-Reperfusion Injury by Modulating <span class="hlt">Systemic</span> <span class="hlt">Iron</span> Homeostasis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Scindia, Yogesh; Dey, Paromita; Thirunagari, Abhinav; Liping, Huang; Rosin, Diane L; Floris, Matteo; Okusa, Mark D; Swaminathan, Sundararaman</p> <p>2015-11-01</p> <p><span class="hlt">Iron</span>-mediated oxidative stress is implicated in the pathogenesis of renal ischemia-reperfusion injury. Hepcidin is an endogenous acute phase hepatic hormone that prevents <span class="hlt">iron</span> export from cells by inducing degradation of the only known <span class="hlt">iron</span> export protein, ferroportin. In this study, we used a mouse model to investigate the effect of renal ischemia-reperfusion injury on <span class="hlt">systemic</span> <span class="hlt">iron</span> homeostasis and determine if dynamic modulation of <span class="hlt">iron</span> homeostasis with hepcidin has therapeutic benefit in the treatment of AKI. Renal ischemia-reperfusion injury induced hepatosplenic <span class="hlt">iron</span> export through increased ferroportin expression, which resulted in hepatosplenic <span class="hlt">iron</span> depletion and an increase in serum and kidney nonheme <span class="hlt">iron</span> levels. Exogenous hepcidin treatment prevented renal ischemia-reperfusion-induced changes in <span class="hlt">iron</span> homeostasis. Hepcidin also decreased kidney ferroportin expression and increased the expression of cytoprotective H-ferritin. Hepcidin-induced restoration of <span class="hlt">iron</span> homeostasis was accompanied by a significant reduction in ischemia-reperfusion-induced tubular injury, apoptosis, renal oxidative stress, and inflammatory cell infiltration. Hepcidin -: deficient mice demonstrated increased susceptibility to ischemia-reperfusion injury compared with wild-type mice. Reconstituting hepcidin-deficient mice with exogenous hepcidin induced hepatic <span class="hlt">iron</span> sequestration, attenuated the reduction in renal H-ferritin and reduced renal oxidative stress, apoptosis, inflammation, and tubular injury. Hepcidin-mediated protection was associated with reduced serum IL-6 levels. In summary, renal ischemia-reperfusion injury results in profound alterations in <span class="hlt">systemic</span> <span class="hlt">iron</span> homeostasis. Hepcidin treatment restores <span class="hlt">iron</span> homeostasis and reduces inflammation to mediate protection in renal ischemia-reperfusion injury, suggesting that hepcidin-ferroportin pathway holds promise as a novel therapeutic target in the treatment of AKI.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=mathematics+AND+transport&pg=2&id=EJ193208','ERIC'); return false;" href="http://eric.ed.gov/?q=mathematics+AND+transport&pg=2&id=EJ193208"><span id="translatedtitle">A Course in <span class="hlt">Transport</span> Phenomena in Multicomponent, Multiphase, Reacting <span class="hlt">Systems</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Carbonell, R. G.; Whitaker, S.</p> <p>1978-01-01</p> <p>This course concentrates on a rigorous development of the multicomponent <span class="hlt">transport</span> equations, boundary conditions at phase interfaces, and volume-averaged <span class="hlt">transport</span> equations for multiphase reacting <span class="hlt">systems</span>. (BB)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/456744','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/456744"><span id="translatedtitle">The Palm Desert Renewable Hydrogen <span class="hlt">Transportation</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lehman, P.</p> <p>1996-10-01</p> <p>The present paper describes, for purposes of the Department of Energy (DoE) Hydrogen Program Review, Schatz Energy Research Center (SERC) progress on the Palm Desert Renewable Hydrogen <span class="hlt">Transportation</span> <span class="hlt">System</span> Project for the period January through June 1996. This period represents the first six months of the three year project. The estimated cost over three years is $3.9M, $1.859M of which is funded by the DoE ($600 k for fiscal year 1996). The goal of the Palm Desert Project is to develop a clean and sustainable <span class="hlt">transportation</span> <span class="hlt">system</span> for a community. The project will demonstrate the practical utility of hydrogen as a <span class="hlt">transportation</span> fuel and proton exchange membrane (PEM) fuel cells as vehicle power plants. This <span class="hlt">transportation</span> <span class="hlt">system</span> will be developed in the City of Palm Desert in southern California and will include a fleet of 8 fuel cell powered vehicles, solar and wind powered hydrogen generating facilities, a consumer-ready refueling station, and a service infrastructure. The <span class="hlt">system</span> holds the promise of a clean environment and an energy supply that is predictable, domestic, safe, and abundant. During, the first part of 1996 SERC has nearly completed building a fuel cell powered personal utility vehicle, which features an upgraded safety and computer <span class="hlt">system</span>; they have designed and built a test bench that is able to mimic golf cart loads and test fuel cell <span class="hlt">system</span> auxiliary components; they have begun the design of the solar hydrogen generating station; they have worked with Sandia National Laboratory on an advanced metal hydride storage <span class="hlt">system</span>; they have increased the power density of the SERC fuel cell by as much as 50%; and they have reached out to the rest of the world with a new fact sheet, world wide web pages, a press release, video footage for a television program. and instruction within the community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1013841','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1013841"><span id="translatedtitle">Liners for ion <span class="hlt">transport</span> membrane <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Carolan, Michael Francis; Miller, Christopher Francis</p> <p>2010-08-10</p> <p>Ion <span class="hlt">transport</span> membrane <span class="hlt">system</span> comprising (a) a pressure vessel comprising an interior, an exterior, an inlet, an inlet conduit, an outlet, and an outlet conduit; (b) a plurality of planar ion <span class="hlt">transport</span> membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein the inlet and the outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; (c) a gas manifold having an interior surface wherein the gas manifold is in flow communication with the interior region of each of the planar ion <span class="hlt">transport</span> membrane modules and with the exterior of the pressure vessel; and (d) a liner disposed within any of the inlet conduit, the outlet conduit, and the interior surface of the gas manifold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9856986','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9856986"><span id="translatedtitle">Expression of SFT (stimulator of Fe <span class="hlt">transport</span>) is enhanced by <span class="hlt">iron</span> chelation in HeLa cells and by hemochromatosis in liver.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yu, J; Yu, Z K; Wessling-Resnick, M</p> <p>1998-12-25</p> <p>SFT (stimulator of Fe <span class="hlt">transport</span>) is a novel <span class="hlt">transport</span> protein that has been found to facilitate uptake of <span class="hlt">iron</span> presented to cells as either Fe(II) or Fe(III). When HeLa cells are exposed to the <span class="hlt">iron</span> chelator desferrioxamine, levels of SFT mRNA increase in an actinomycin D-sensitive manner. In contrast, cells exposed to high levels of <span class="hlt">iron</span> down-regulate SFT expression in a time-dependent and reversible fashion. Thus, homeostatic regulation of SFT expression not only ensures that sufficient levels of <span class="hlt">iron</span> are maintained but also limits excessive assimilation to prevent potentially harmful effects of this toxic metal. The unexpected observation that SFT transcript levels are up-regulated in hemochromatosis patients therefore suggests that enhanced SFT expression contributes to the etiology of this <span class="hlt">iron</span> overload disorder.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4501554','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4501554"><span id="translatedtitle">Interacting Effects of Light and <span class="hlt">Iron</span> Availability on the Coupling of Photosynthetic Electron <span class="hlt">Transport</span> and CO2-Assimilation in Marine Phytoplankton</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T.; Tortell, Philippe D.</p> <p>2015-01-01</p> <p><span class="hlt">Iron</span> availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of <span class="hlt">iron</span> is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron <span class="hlt">transport</span> in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to <span class="hlt">iron</span> limitation. In this study, we examine the role of <span class="hlt">iron</span> limitation, and the interacting effects of <span class="hlt">iron</span> and light availability, on the coupling of photosynthetic electron <span class="hlt">transport</span> and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron <span class="hlt">transport</span>, particularly under <span class="hlt">iron</span> limiting conditions. We observed that reaction center II specific rates of electron <span class="hlt">transport</span> (ETRRCII, mol e- mol RCII-1 s-1) increased under <span class="hlt">iron</span> limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements. PMID:26171963</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990saei.conf.....R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990saei.conf.....R"><span id="translatedtitle">Thermal protection <span class="hlt">systems</span> for hypersonic <span class="hlt">transport</span> vehicles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reich, G.; Hinger, J.; Huchler, M.</p> <p>1990-07-01</p> <p>Thermal protection <span class="hlt">systems</span> (TPS) for hypersonic <span class="hlt">transport</span> vehicles are described and evaluated. During the flight through the atmosphere moderate to high aerodynamic heating rates with corresponding high surface temperatures are generated. Therefore, a reliable light-weight but effective TPS is required, that limits the heat transfer into the central fuselage with the liquid hydrogen tank and that prevents the penetration of the temperature peak during stage separation to the load carrying structure. The heat transfer modes in the insulation are solid conduction, gas convection and radiation. Thermal protection <span class="hlt">systems</span> based on different phenomena to reduce the heat transfer, like vacuum shingles, inert gas filled shingles, microporous insulations and multiwall structures, are described. It is demonstrated that microporous and multiwall insulations are efficient, light weight and reliable TPSs for future hypersonic <span class="hlt">transportation</span> <span class="hlt">systems</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ASPC..485..109F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ASPC..485..109F"><span id="translatedtitle">DTS: The NOAO Data <span class="hlt">Transport</span> <span class="hlt">System</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fitzpatrick, M.; Semple, T.</p> <p>2014-05-01</p> <p>The NOAO Data <span class="hlt">Transport</span> <span class="hlt">System</span> (DTS) provides high-throughput, reliable, data transfer between telescopes, pipelines and archive centers located in the Northern and Southern hemispheres. It is a distributed application using XML-RPC for command and control, and either parallel-TCP or UDT protocols for bulk data <span class="hlt">transport</span>. The <span class="hlt">system</span> is data-agnostic, allowing arbitrary files or directories to be moved using the same infrastructure. Data paths are configurable in the <span class="hlt">system</span> by connecting nodes as the source or destination of data in a queue. Each leg of a data path may be configured independently based on the network environment between the sites. A queueing model is currently implemented to manage the automatic movement of data, a streaming model is planned to support arbitrarily large transfers (e.g. as in a disk recovery scenario) or to provide a 'pass-thru' interface to minize overheads. A web-based monitor allows anyone to get a graphical overview of the DTS <span class="hlt">system</span> as it runs, operators will be able to control individual nodes in the <span class="hlt">system</span>. Through careful tuning of the network paths DTS is able to achieve in excess of 80-percent of the nominal wire speed using only commodity networks, making it ideal for long-haul <span class="hlt">transport</span> of large volumes of data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21179420','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21179420"><span id="translatedtitle">Role of the Yersinia pestis yersiniabactin <span class="hlt">iron</span> acquisition <span class="hlt">system</span> in the incidence of flea-borne plague.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sebbane, Florent; Jarrett, Clayton; Gardner, Donald; Long, Daniel; Hinnebusch, B Joseph</p> <p>2010-12-17</p> <p>Plague is a flea-borne zoonosis caused by the bacterium Yersinia pestis. Y. pestis mutants lacking the yersiniabactin (Ybt) siderophore-based <span class="hlt">iron</span> <span class="hlt">transport</span> <span class="hlt">system</span> are avirulent when inoculated intradermally but fully virulent when inoculated intravenously in mice. Presumably, Ybt is required to provide sufficient <span class="hlt">iron</span> at the peripheral injection site, suggesting that Ybt would be an essential virulence factor for flea-borne plague. Here, using a flea-to-mouse transmission model, we show that a Y. pestis strain lacking the Ybt <span class="hlt">system</span> causes fatal plague at low incidence when transmitted by fleas. Bacteriology and histology analyses revealed that a Ybt-negative strain caused only primary septicemic plague and atypical bubonic plague instead of the typical bubonic form of disease. The results provide new evidence that primary septicemic plague is a distinct clinical entity and suggest that unusual forms of plague may be caused by atypical Y. pestis strains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870004013','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870004013"><span id="translatedtitle">Automatic braking <span class="hlt">system</span> modification for the Advanced <span class="hlt">Transport</span> Operating <span class="hlt">Systems</span> (ATOPS) <span class="hlt">Transportation</span> <span class="hlt">Systems</span> Research Vehicle (TSRV)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coogan, J. J.</p> <p>1986-01-01</p> <p>Modifications were designed for the B-737-100 Research Aircraft autobrake <span class="hlt">system</span> hardware of the Advanced <span class="hlt">Transport</span> Operating <span class="hlt">Systems</span> (ATOPS) Program at Langley Research Center. These modifications will allow the on-board flight control computer to control the aircraft deceleration after landing to a continuously variable level for the purpose of executing automatic high speed turn-offs from the runway. A bread board version of the proposed modifications was built and tested in simulated stopping conditions. Test results, for various aircraft weights, turnoff speed, winds, and runway conditions show that the turnoff speeds are achieved generally with errors less than 1 ft/sec.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12547240','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12547240"><span id="translatedtitle">Transferrin receptor 1 (TfR1) and putative stimulator of Fe <span class="hlt">transport</span> (SFT) expression in <span class="hlt">iron</span> deficiency and overload: an overview.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barisani, Donatella; Conte, Dario</p> <p>2002-01-01</p> <p>Transferrin Receptor 1 (TfR1) and putative Stimulator of Fe <span class="hlt">Transport</span> (SFT) represent two different proteins involved in <span class="hlt">iron</span> metabolism in mammalian cells. The expression of TfR1 in the duodenum of subjects with normal body <span class="hlt">iron</span> stores has been mainly localized in the basolateral portion of the cytoplasm of crypt cells, supporting the idea that this molecule may be involved in the sensing of body <span class="hlt">iron</span> stores. In <span class="hlt">iron</span> deficiency anemia TfR1 expression demonstrated an inverse relationship with body <span class="hlt">iron</span> stores as assessed by immunohistochemistry with anti-TfR1 antibodies. In <span class="hlt">iron</span> overload, TfR1 expression in the duodenum differed according to the presence or absence of the C282Y mutation in the HFE gene, being increased in HFE-related hemochromatosis and similar to controls in non-HFE-related <span class="hlt">iron</span> overload. SFT is characterized by its ability to increase <span class="hlt">iron</span> <span class="hlt">transport</span> both through the transferrin dependent and independent uptake, and could thus affect <span class="hlt">iron</span> absorption in the intestine. Immunohistochemistry using anti-SFT antibodies which recognize a putative stimulator of Fe <span class="hlt">transport</span> of approximately 80 KDa revealed a localization of this protein in the apical part of the cytoplasm of enterocytes localized at the tip of the villi. The expression of the protein recognized by these antibodies was increased in <span class="hlt">iron</span> deficiency, as well as in patients carrying the C282Y HFE mutation. Thus, the increased expression of both proteins only in patients with HFE-related hemochromatosis suggests that other factors should be involved in determining non-HFE-related <span class="hlt">iron</span> overload.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050207435','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050207435"><span id="translatedtitle">Small Aircraft <span class="hlt">Transportation</span> <span class="hlt">System</span> Concept and Technologies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Holmes, Bruce J.; Durham, Michael H.; Tarry, Scott E.</p> <p>2005-01-01</p> <p>This paper summarizes both the vision and the early public-private collaborative research for the Small Aircraft <span class="hlt">Transportation</span> <span class="hlt">System</span> (SATS). The paper outlines an operational definition of SATS, describes how SATS conceptually differs from current air <span class="hlt">transportation</span> capabilities, introduces four SATS operating capabilities, and explains the relation between the SATS operating capabilities and the potential for expanded air mobility. The SATS technology roadmap encompasses on-demand, widely distributed, point-to-point air mobility, through hired-pilot modes in the nearer-term, and through self-operated user modes in the farther-term. The nearer-term concept is based on aircraft and airspace technologies being developed to make the use of smaller, more widely distributed community reliever and general aviation airports and their runways more useful in more weather conditions, in commercial hired-pilot service modes. The farther-term vision is based on technical concepts that could be developed to simplify or automate many of the operational functions in the aircraft and the airspace for meeting future public <span class="hlt">transportation</span> needs, in personally operated modes. NASA technology strategies form a roadmap between the nearer-term concept and the farther-term vision. This paper outlines a roadmap for scalable, on-demand, distributed air mobility technologies for vehicle and airspace <span class="hlt">systems</span>. The audiences for the paper include General Aviation manufacturers, small aircraft <span class="hlt">transportation</span> service providers, the flight training industry, airport and <span class="hlt">transportation</span> authorities at the Federal, state and local levels, and organizations involved in planning for future National Airspace <span class="hlt">System</span> advancements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25387073','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25387073"><span id="translatedtitle">An uncleaved signal peptide directs the Malus xiaojinensis <span class="hlt">iron</span> <span class="hlt">transporter</span> protein Mx IRT1 into the ER for the PM secretory pathway.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Peng; Tan, Song; Berry, James O; Li, Peng; Ren, Na; Li, Shuang; Yang, Guang; Wang, Wei-Bing; Qi, Xiao-Ting; Yin, Li-Ping</p> <p>2014-11-07</p> <p>Malus xiaojinensis <span class="hlt">iron</span>-regulated <span class="hlt">transporter</span> 1 (Mx IRT1) is a highly effective inducible <span class="hlt">iron</span> <span class="hlt">transporter</span> in the <span class="hlt">iron</span> efficient plant Malus xiaojinensis. As a multi-pass integral plasma membrane (PM) protein, Mx IRT1 is predicted to consist of eight transmembrane domains, with a putative N-terminal signal peptide (SP) of 1-29 amino acids. To explore the role of the putative SP, constructs expressing Mx IRT1 (with an intact SP) and Mx DsIRT1 (with a deleted SP) were prepared for expression in Arabidopsis and in yeast. Mx IRT1 could rescue the <span class="hlt">iron</span>-deficiency phenotype of an Arabidopsis irt1 mutant, and complement the <span class="hlt">iron</span>-limited growth defect of the yeast mutant DEY 1453 (fet3fet4). Furthermore, fluorescence analysis indicated that a chimeric Mx IRT1-eGFP (enhanced Green Fluorescent Protein) construct was translocated into the ER (Endoplasmic reticulum) for the PM sorting pathway. In contrast, the SP-deleted Mx DsIRT1 could not rescue either of the mutant phenotypes, nor direct <span class="hlt">transport</span> of the GFP signal into the ER. Interestingly, immunoblot analysis indicated that the SP was not cleaved from the mature protein following <span class="hlt">transport</span> into the ER. Taken together, data presented here provides strong evidence that an uncleaved SP determines ER-targeting of Mx IRT1 during the initial sorting stage, thereby enabling the subsequent <span class="hlt">transport</span> and integration of this protein into the PM for its crucial role in <span class="hlt">iron</span> uptake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16835119','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16835119"><span id="translatedtitle">Influences of water treatment process on <span class="hlt">iron</span> and copper release in distribution <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shi, Baoyou; Xiao, Weizhong; Taylor, James S</p> <p>2006-01-01</p> <p>A pilot study was conducted to assess the effect of water quality changes on <span class="hlt">iron</span> and copper release in distribution <span class="hlt">systems</span>. Three finished waters were prepared from groundwater source by conventional treatment, lime softening and reverse osmosis (RO). To mimic desalinated seawater, sea salts were added to RO treated water. Both lime softening and RO treatment significantly decreased the calcium concentration and alkalinity of groundwater. During a yearlong investigation, the impact of seasonal changes on <span class="hlt">iron</span> and copper release was also evaluated. The results showed that groundwater after lime softening slightly increased <span class="hlt">iron</span> release potential but significantly decreased copper release. Desalination water caused much higher <span class="hlt">iron</span> release but lower copper release than conventionally treated groundwater. Blended water with conventional groundwater and desalination water resulted in intermediate <span class="hlt">iron</span> release but much high copper release. Both <span class="hlt">iron</span> and copper release could be accelerated by temperature increase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22376189','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22376189"><span id="translatedtitle"><span class="hlt">Iron</span> starvation regulates the type III secretion <span class="hlt">system</span> in Bordetella bronchiseptica.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kurushima, Jun; Kuwae, Asaomi; Abe, Akio</p> <p>2012-06-01</p> <p>The type III secretion <span class="hlt">system</span> (T3SS) plays a key role in the exertion of full virulence by Bordetella bronchiseptica. However, little is known about the environmental stimuli that induce expression of T3SS genes. Here, it is reported that <span class="hlt">iron</span> starvation is a signal for T3SS gene expression in B. bronchiseptica. It was found that, when B. bronchiseptica is cultured under <span class="hlt">iron</span>-depleted conditions, secretion of type III secreted proteins is greater than that in bacteria grown under <span class="hlt">iron</span>-replete conditions. Furthermore, it was confirmed that induction of T3SS-dependent host cell cytotoxicity and hemolytic activity is greatly enhanced by infection with <span class="hlt">iron</span>-depleted Bordetella. In contrast, production of filamentous hemagglutinin is reduced in <span class="hlt">iron</span>-depleted Bordetella. Thus, B. bronchiseptica controls the expression of virulence genes in response to <span class="hlt">iron</span> starvation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/229566','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/229566"><span id="translatedtitle">Road <span class="hlt">Transportable</span> Analytical Laboratory (RTAL) <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Finger, S.M.</p> <p>1995-10-01</p> <p>The goal of the Road <span class="hlt">Transportable</span> Analytical Laboratory (RTAL) Project is the development and demonstration of a <span class="hlt">system</span> to meet the unique needs of the DOE for rapid, accurate analysis of a wide variety of hazardous and radioactive contaminants in soil, groundwater, and surface waters. This laboratory <span class="hlt">system</span> has been designed to provide the field and laboratory analytical equipment necessary to detect and quantify radionuclides, organics, heavy metals and other inorganic compounds. The laboratory <span class="hlt">system</span> consists of a set of individual laboratory modules deployable independently or as an interconnected group to meet each DOE site`s specific needs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940012847','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940012847"><span id="translatedtitle">Human <span class="hlt">Transportation</span> <span class="hlt">System</span> (HTS) study, volume 2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lance, N.; Geyer, M. S.; Gaunce, M. T.</p> <p>1993-01-01</p> <p>This report summarizes work completed under the Human <span class="hlt">Transportation</span> <span class="hlt">System</span> Study. This study was conducted by the New Initiatives Office at JSC with the technical support of Boeing, General Dynamics, Lockheed, McDonnell-Douglas, Martin Marietta, and Rockwell. The study was designed to generate information on determining the appropriate path to follow for new <span class="hlt">system</span> development to meet the Nation's space <span class="hlt">transportation</span> needs. The study evaluates 18 <span class="hlt">transportation</span> architecture options using a parametric set of mission requirements. These options include use of current <span class="hlt">systems</span> (e.g., Shuttle, Titan, etc. ) as well as proposed <span class="hlt">systems</span> (e.g., PLS, Single-Stage-to-Orbit, etc.) to assess the impact of various considerations, such as the cost of alternate access, or the benefit of separating people and cargo. The architecture options are compared to each other with six measurable evaluation criteria or attributes. They are: funding profile, human safety, probability of mission success, architecture cost risk, launch schedule confidence, and environmental impact. Values for these attributes are presented for the architecture options, with pertinent conclusions and recommendations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993nasa.reptQR...L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993nasa.reptQR...L"><span id="translatedtitle">Human <span class="hlt">Transportation</span> <span class="hlt">System</span> (HTS) study, volume 2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lance, N.; Geyer, M. S.; Gaunce, M. T.</p> <p>1993-10-01</p> <p>This report summarizes work completed under the Human <span class="hlt">Transportation</span> <span class="hlt">System</span> Study. This study was conducted by the New Initiatives Office at JSC with the technical support of Boeing, General Dynamics, Lockheed, McDonnell-Douglas, Martin Marietta, and Rockwell. The study was designed to generate information on determining the appropriate path to follow for new <span class="hlt">system</span> development to meet the Nation's space <span class="hlt">transportation</span> needs. The study evaluates 18 <span class="hlt">transportation</span> architecture options using a parametric set of mission requirements. These options include use of current <span class="hlt">systems</span> (e.g., Shuttle, Titan, etc. ) as well as proposed <span class="hlt">systems</span> (e.g., PLS, Single-Stage-to-Orbit, etc.) to assess the impact of various considerations, such as the cost of alternate access, or the benefit of separating people and cargo. The architecture options are compared to each other with six measurable evaluation criteria or attributes. They are: funding profile, human safety, probability of mission success, architecture cost risk, launch schedule confidence, and environmental impact. Values for these attributes are presented for the architecture options, with pertinent conclusions and recommendations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.B11B0366M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.B11B0366M"><span id="translatedtitle">Aqueous <span class="hlt">Iron</span>-Sulfide Clusters in Variably Saturated Soil <span class="hlt">Systems</span>: Implications for <span class="hlt">Iron</span> Cycling and Fluid Flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGuire, J. T.; Hansen, D. J.; Mohanty, B. P.</p> <p>2008-12-01</p> <p><span class="hlt">Iron</span> and sulfur cycling is an important control on contaminant fate and <span class="hlt">transport</span>, the availability of micronutrients and the physics of water flow. This study explores the effects of soil structure (i.e. layers, lenses, macropores, or fractures) on linked biogeochemical and hydrological processes involving Fe and S cycling in the vadose zone using packed soil columns. Three laboratory soil columns were constructed: a homogenized medium-grained sand, homogenized organic-rich loam, and a sand-over-loam layered column. Both upward and downward infiltration of water was evaluated during experiments to simulate rising water table and rainfall events respectively. Water samples extracted by lysimeter were analyzed for reduced species (including total sulfide, Fe(II), and FeSaq) voltammetrically using a mercury drop electrode. In addition to other reduced species, aqueous FeS clusters (FeSaq) were observed in two of the columns, with the greatest concentrations of FeSaq occurring in close proximity to the soil interface in the layered column. To our knowledge, this is the first documentation of aqueous FeS clusters in partially saturated sediments. The aqueous nature of FeSaq allows it to be <span class="hlt">transported</span> instead of precipitating and suggests that current conceptual models of <span class="hlt">iron</span>-sulfur cycling may need to be adapted to account for an aqueous phase. The presence of <span class="hlt">iron</span>-rich soil aggregates near the soil interface may indicate that FeS clusters played a critical role in the formation of soil aggregates that subsequently caused up to an order of magnitude decrease in hydraulic conductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22391440','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22391440"><span id="translatedtitle">Low energy beam <span class="hlt">transport</span> <span class="hlt">system</span> developments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.</p> <p>2015-04-08</p> <p>For high brightness beam production it is important to preserve the brightness in the low energy beam <span class="hlt">transport</span> <span class="hlt">system</span> (LEBT) used to <span class="hlt">transport</span> and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam <span class="hlt">transport</span>, reliable electrostatic LEBT operation has been demonstrated with H{sup −} beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam <span class="hlt">transport</span>. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H{sup −} beams, but such gas densities cause unacceptably high H{sup −} beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for <span class="hlt">transport</span> of high current H{sup −} beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable <span class="hlt">transport</span> of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1745900','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1745900"><span id="translatedtitle"><span class="hlt">Iron</span> deficiency.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Scrimshaw, N S</p> <p>1991-10-01</p> <p>The world's leading nutritional problem is <span class="hlt">iron</span> deficiency. 66% of children and women aged 15-44 years in developing countries have it. Further, 10-20% of women of childbearing age in developed countries are anemic. <span class="hlt">Iron</span> deficiency is identified with often irreversible impairment of a child's learning ability. It is also associated with low capacity for adults to work which reduces productivity. In addition, it impairs the immune <span class="hlt">system</span> which reduces the body's ability to fight infection. <span class="hlt">Iron</span> deficiency also lowers the metabolic rate and the body temperature when exposed to cold. Hemoglobin contains nearly 73% of the body's <span class="hlt">iron</span>. This <span class="hlt">iron</span> is always being recycled as more red blood cells are made. The rest of the needed <span class="hlt">iron</span> does important tasks for the body, such as binds to molecules that are reservoirs of oxygen for muscle cells. This <span class="hlt">iron</span> comes from our diet, especially meat. Even though some plants, such as spinach, are high in <span class="hlt">iron</span>, the body can only absorb 1.4-7% of the <span class="hlt">iron</span> in plants whereas it can absorb 20% of the <span class="hlt">iron</span> in red meat. In many developing countries, the common vegetarian diets contribute to high rates of <span class="hlt">iron</span> deficiency. Parasitic diseases and abnormal uterine bleeding also promote <span class="hlt">iron</span> deficiency. <span class="hlt">Iron</span> therapy in anemic children can often, but not always, improve behavior and cognitive performance. <span class="hlt">Iron</span> deficiency during pregnancy often contributes to maternal and perinatal mortality. Yet treatment, if given to a child in time, can lead to normal growth and hinder infections. However, excess <span class="hlt">iron</span> can be damaging. Too much supplemental <span class="hlt">iron</span> in a malnourished child promotes fatal infections since the excess <span class="hlt">iron</span> is available for the pathogens use. Many countries do not have an effective <span class="hlt">system</span> for diagnosing, treating, and preventing <span class="hlt">iron</span> deficiency. Therefore a concerted international effort is needed to eliminate <span class="hlt">iron</span> deficiency in the world.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830007769','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830007769"><span id="translatedtitle">Controlled ecological life support <span class="hlt">system</span>: <span class="hlt">Transportation</span> analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gustan, E.; Vinopal, T.</p> <p>1982-01-01</p> <p>This report discusses a study utilizing a <span class="hlt">systems</span> analysis approach to determine which NASA missions would benefit from controlled ecological life support <span class="hlt">system</span> (CELSS) technology. The study focuses on manned missions selected from NASA planning forecasts covering the next half century. Comparison of various life support scenarios for the selected missions and characteristics of projected <span class="hlt">transportation</span> <span class="hlt">systems</span> provided data for cost evaluations. This approach identified missions that derived benefits from a CELSS, showed the magnitude of the potential cost savings, and indicated which <span class="hlt">system</span> or combination of <span class="hlt">systems</span> would apply. This report outlines the analytical approach used in the evaluation, describes the missions and <span class="hlt">systems</span> considered, and sets forth the benefits derived from CELSS when applicable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec236-532.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec236-532.pdf"><span id="translatedtitle">49 CFR 236.532 - Strap <span class="hlt">iron</span> inductor; use restricted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 4 2010-10-01 2010-10-01 false Strap <span class="hlt">iron</span> inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal <span class="hlt">Systems</span> Rules and Instructions; Roadway § 236.532 Strap <span class="hlt">iron</span> inductor; use restricted. No railroad shall use strap <span class="hlt">iron</span> inductor or other roadway element...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec236-532.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec236-532.pdf"><span id="translatedtitle">49 CFR 236.532 - Strap <span class="hlt">iron</span> inductor; use restricted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 4 2011-10-01 2011-10-01 false Strap <span class="hlt">iron</span> inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal <span class="hlt">Systems</span> Rules and Instructions; Roadway § 236.532 Strap <span class="hlt">iron</span> inductor; use restricted. No railroad shall use strap <span class="hlt">iron</span> inductor or other roadway element...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec236-532.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec236-532.pdf"><span id="translatedtitle">49 CFR 236.532 - Strap <span class="hlt">iron</span> inductor; use restricted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 4 2012-10-01 2012-10-01 false Strap <span class="hlt">iron</span> inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal <span class="hlt">Systems</span> Rules and Instructions; Roadway § 236.532 Strap <span class="hlt">iron</span> inductor; use restricted. No railroad shall use strap <span class="hlt">iron</span> inductor or other roadway element...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec236-532.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec236-532.pdf"><span id="translatedtitle">49 CFR 236.532 - Strap <span class="hlt">iron</span> inductor; use restricted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 4 2013-10-01 2013-10-01 false Strap <span class="hlt">iron</span> inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal <span class="hlt">Systems</span> Rules and Instructions; Roadway § 236.532 Strap <span class="hlt">iron</span> inductor; use restricted. No railroad shall use strap <span class="hlt">iron</span> inductor or other roadway element...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec236-532.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec236-532.pdf"><span id="translatedtitle">49 CFR 236.532 - Strap <span class="hlt">iron</span> inductor; use restricted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-10-01</p> <p>... 49 <span class="hlt">Transportation</span> 4 2014-10-01 2014-10-01 false Strap <span class="hlt">iron</span> inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal <span class="hlt">Systems</span> Rules and Instructions; Roadway § 236.532 Strap <span class="hlt">iron</span> inductor; use restricted. No railroad shall use strap <span class="hlt">iron</span> inductor or other roadway element...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7246077','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/7246077"><span id="translatedtitle">Heat <span class="hlt">transport</span> <span class="hlt">system</span>, method and material</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Musinski, D.L.</p> <p>1987-04-28</p> <p>A heat <span class="hlt">transport</span> <span class="hlt">system</span>, method and composite material are disclosed in which a plurality of hollow spherical shells or microspheres having an outside diameter of less than or equal to 500 microns are encapsulated or embedded within a bulk material. Each shell has captured therein a volatile working fluid, such that each shell operates as a microsized heat pipe for conducting heat through the composite structure. 1 fig.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MS%26E...86a2016K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MS%26E...86a2016K"><span id="translatedtitle">Stages of vermicular cast <span class="hlt">iron</span> properties modeling in the intelligent design <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klochkova, K. V.; Petrovich, S. V.; Simonova, L. A.; Yusupov, L. R.</p> <p>2015-06-01</p> <p>This article presents the structure of intelligent <span class="hlt">system</span> of the cast <span class="hlt">iron</span> with vermicular graphite <span class="hlt">iron</span> (CGI) design under the conditions of current production, the technique of the optimal process TP parameters of the production of CGI parts in the preparatory phase of production based on mental models is designed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760020076','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760020076"><span id="translatedtitle">Cargo <span class="hlt">transportation</span> by airships: A <span class="hlt">systems</span> study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huang, C. J.; Dalton, C.</p> <p>1976-01-01</p> <p>A <span class="hlt">systems</span> engineering study of a lighter than air airship <span class="hlt">transportation</span> <span class="hlt">system</span> was conducted. The feasibility of the use of airships in hauling cargo was demonstrated. Social, legal, environmental and political factors were considered as well as the technical factors necessary to design an effective airship <span class="hlt">transportation</span> <span class="hlt">system</span>. In order to accomplish an effective airship <span class="hlt">transportation</span> program two phases of implementation were recommended. Phase I would involve a fleet of rigid airships of 3.5 million cubic feet displacement capable of carrying 25 tons of cargo internal to the helium-filled gas bag. The Phase I fleet would demonstrate the economic and technical feasibility of modern-day airships while providing a training capability for the construction and operation of larger airships. The Phase II portion would be a fleet of rigid airships of 12 million cubic feet displacement capable of carrying a cargo of 100 tons a distance of 2,000 miles at a cruising speed of 60 mph. An economic analysis is given for a variety of missions for both Phase I and Phase II airships.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/305627','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/305627"><span id="translatedtitle">The Palm Desert renewable [hydrogen] <span class="hlt">transportation</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chamberlin, C.E.; Lehman, P.</p> <p>1998-08-01</p> <p>This paper describes the Schatz Energy Research Center (SERC) progress on the Palm Desert Renewable Hydrogen <span class="hlt">Transportation</span> <span class="hlt">System</span> Project for the period June 1997 through May 1998. The project began in March 1996. The goal of the Palm Desert Project is to develop a clean and sustainable <span class="hlt">transportation</span> <span class="hlt">system</span> for a community. The project demonstrates the practical utility of hydrogen as a <span class="hlt">transportation</span> fuel and the proton exchange membrane (PEM) fuel cell as a vehicle power <span class="hlt">system</span>. The project includes designing and building 4 fuel cell powered vehicles, a solar hydrogen generating and refueling station, and a fuel cell vehicle diagnostic center. Over this last year, SERC has built a fuel cell powered neighborhood electric vehicle and delivered it to the City of Palm Desert. The design of the hydrogen refueling station is near completion and it is anticipated that construction will be complete in the fall of 1998. The vehicles are currently being refueled at a temporary refueling station. The diagnostic center is being designed and maintenance procedures as well as computer diagnostic programs for the fuel cell vehicles are being developed. City employees are driving the vehicles daily and monitoring data are being collected. The drivers are pleased with the performance of the vehicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26356897','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26356897"><span id="translatedtitle">Visualizing Mobility of Public <span class="hlt">Transportation</span> <span class="hlt">System</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zeng, Wei; Fu, Chi-Wing; Arisona, Stefan Müller; Erath, Alexander; Qu, Huamin</p> <p>2014-12-01</p> <p>Public <span class="hlt">transportation</span> <span class="hlt">systems</span> (PTSs) play an important role in modern cities, providing shared/massive <span class="hlt">transportation</span> services that are essential for the general public. However, due to their increasing complexity, designing effective methods to visualize and explore PTS is highly challenging. Most existing techniques employ network visualization methods and focus on showing the network topology across stops while ignoring various mobility-related factors such as riding time, transfer time, waiting time, and round-the-clock patterns. This work aims to visualize and explore passenger mobility in a PTS with a family of analytical tasks based on inputs from <span class="hlt">transportation</span> researchers. After exploring different design alternatives, we come up with an integrated solution with three visualization modules: isochrone map view for geographical information, isotime flow map view for effective temporal information comparison and manipulation, and OD-pair journey view for detailed visual analysis of mobility factors along routes between specific origin-destination pairs. The isotime flow map linearizes a flow map into a parallel isoline representation, maximizing the visualization of mobility information along the horizontal time axis while presenting clear and smooth pathways from origin to destinations. Moreover, we devise several interactive visual query methods for users to easily explore the dynamics of PTS mobility over space and time. Lastly, we also construct a PTS mobility model from millions of real passenger trajectories, and evaluate our visualization techniques with assorted case studies with the <span class="hlt">transportation</span> researchers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910018897','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910018897"><span id="translatedtitle">Next generation: In-space <span class="hlt">transportation</span> <span class="hlt">system(s</span>)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huffaker, Fredrick; Redus, Jerry; Kelley, David L.</p> <p>1991-01-01</p> <p>The development of the next generation In-Space <span class="hlt">Transportation</span> <span class="hlt">System</span> presents a unique challenge to the design of a propulsion <span class="hlt">system</span> for the Space Exploration Initiative (SEI). Never before have the requirements for long-life, multiple mission use, space basing, high reliability, man-rating, and minimum maintenance come together with performance in one <span class="hlt">system</span> that must protect the lives of space travelers, support the mission logistics needs, and do so at an acceptable cost. The challenge that is presented is to quantify the bounds of these requirements. The issue is one of degree. The length of acceptable life in space, the time it takes for reuse to pay off, and the degree to which space basing is practical (full, partial, or expended) are the issues that determine the reusable bounds of a design and include dependability, contingency capabilities, resilency, and minimum dependence on a maintenance node in preparation for and during a mission. Missions to planet earth, other non-NASA missions, and planetary missions will provide important but less demanding requirements for the <span class="hlt">transportation</span> <span class="hlt">systems</span> of the future. The mission proposed for the SEI require a family of <span class="hlt">transportation</span> vehicles to meet the requirements for establishing a permanent human presence on the Moon and eventually on Mars. Specialized vehicles are needed to accomplish the different phases of each mission. These large scale missions require assembly in space and will provide the greatest usage of the planned integrated <span class="hlt">transportation</span> <span class="hlt">system</span>. The current approach to defining the In-Space <span class="hlt">Transportation</span> <span class="hlt">System</span> for the SEI Moon missions with later Mars mission applications is presented. Several <span class="hlt">system</span> development options, propulsion concepts, current/proposed activities are reviewed, and key propulsion design criteria, issues, and technology challenges for the next generation In-Space <span class="hlt">Transportation</span> <span class="hlt">System(s</span>) are outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1274505-high-energy-particle-transport-code-system','SCIGOV-ESTSC'); return false;" href="http://www.osti.gov/scitech/biblio/1274505-high-energy-particle-transport-code-system"><span id="translatedtitle">High Energy Particle <span class="hlt">Transport</span> Code <span class="hlt">System</span>.</span></a></p> <p><a target="_blank" href=""></a></p> <p></p> <p>2003-12-17</p> <p>Version 00 NMTC/JAM is an upgraded version of the code CCC-694/NMTC-JAERI97, which was developed in 1982 at JAERI and is based on the CCC-161/NMTC code <span class="hlt">system</span>. NMTC/JAM simulates high energy nuclear reactions and nuclear meson <span class="hlt">transport</span> processes. The applicable energy range of NMTC/JAM was extended in principle up to 200 GeV for nucleons and mesons by introducing the high energy nuclear reaction code Jet-Aa Microscopic (JAM) for the intra-nuclear cascade part. For the evaporation andmore » fission process, a new model, GEM, can be used to describe the light nucleus production from the excited residual nucleus. According to the extension of the applicable energy, the nucleon-nucleus non-elastic, elastic and differential elastic cross section data were upgraded. In addition, the particle <span class="hlt">transport</span> in a magnetic field was implemented for beam <span class="hlt">transport</span> calculations. Some new tally functions were added, and the format of input and output of data is more user friendly. These new calculation functions and utilities provide a tool to carry out reliable neutronics study of a large scale target <span class="hlt">system</span> with complex geometry more accurately and easily than with the previous model. It implements an intranuclear cascade model taking account of the in-medium nuclear effects and the preequilibrium calculation model based on the exciton one. For treating the nucleon <span class="hlt">transport</span> process, the nucleon-nucleus cross sections are revised to those derived by the systematics of Pearlstein. Moreover, the level density parameter derived by Ignatyuk is included as a new option for particle evaporation calculation. A geometry package based on the Combinatorial Geometry with multi-array <span class="hlt">system</span> and the importance sampling technique is implemented in the code. Tally function is also employed for obtaining such physical quantities as neutron energy spectra, heat deposition and nuclide yield without editing a history file. The code can simulate both the primary spallation reaction and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990067284&hterms=implementation+System+control+internal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dimplementation%2BSystem%2Bcontrol%2Binternal','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990067284&hterms=implementation+System+control+internal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dimplementation%2BSystem%2Bcontrol%2Binternal"><span id="translatedtitle">Miniature Heat <span class="hlt">Transport</span> <span class="hlt">System</span> for Nanosatellite Technology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Douglas, Donya M,</p> <p>1999-01-01</p> <p>The scientific understanding of key physical processes between the Sun and the Earth require simultaneous measurements from many vantage points in space. Nano-satellite technologies will enable a class of constellation missions for the NASA Space Science Sun-Earth Connections. This recent emphasis on the implementation of smaller satellites leads to a requirement for development of smaller subsystems in several areas. Key technologies under development include: advanced miniaturized chemical propulsion; miniaturized sensors; highly integrated, compact electronics; autonomous onboard and ground operations; miniatures low power tracking techniques for orbit determination; onboard RF communications capable of transmitting data to the ground from far distances; lightweight efficient solar array panels; lightweight, high output battery cells; lightweight yet strong composite materials for the nano-spacecraft and deployer-ship structures. These newer smaller <span class="hlt">systems</span> may have higher power densities and higher thermal <span class="hlt">transport</span> requirements than seen on previous small satellites. Furthermore, the small satellites may also have a requirement to maintain thermal control through extended earth shadows, possibly up to 8 hours long. Older thermal control technology, such as heaters, thermostats, and heat pipes, may not be sufficient to meet the requirements of these new <span class="hlt">systems</span>. Conversely, a miniature two-phase heat <span class="hlt">transport</span> <span class="hlt">system</span> (Mini-HTS) such as a Capillary Pumped Loop (CPL) or Loop Heat Pipe (LBP) is a viable alternative. A Mini-HTS can provide fine temperature control, thermal diode action, and a highly efficient means of heat transfer. The Mini-HTS would have power capabilities in the range of tens of watts or less and provide thermal control over typical spacecraft ranges. The Mini-HTS would allow the internal portion of the spacecraft to be thermally isolated from the external radiator, thus protecting the internal components from extreme cold temperatures during an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=108413','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=108413"><span id="translatedtitle">Molecular Cloning of a 32-Kilodalton Lipoprotein Component of a Novel <span class="hlt">Iron</span>-Regulated Staphylococcus epidermidis ABC <span class="hlt">Transporter</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cockayne, Alan; Hill, Philip J.; Powell, Nick B. L.; Bishop, Keith; Sims, Cate; Williams, Paul</p> <p>1998-01-01</p> <p>Our previous studies identified two <span class="hlt">iron</span>-regulated cytoplasmic membrane proteins of 32 and 36 kDa expressed by both Staphylococcus epidermidis and Staphylococcus aureus. In this study we show by Triton X-114 phase partitioning and tritiated palmitic acid labelling that these proteins are lipoproteins which are anchored into the cytoplasmic membrane by their lipid-modified N termini. In common with those of some other gram-positive bacteria, these highly immunogenic lipoproteins were released from the bacterial cell into the culture supernatants, with release being promoted by growth of the bacteria under <span class="hlt">iron</span>-restricted conditions. Immunoelectron microscopy with a monospecific rabbit antiserum to the 32-kDa S. epidermidis lipoprotein showed that the majority of the antigen was distributed throughout the staphylococcal cell wall. Only minor quantities were detected in the cytoplasmic membrane, and exposure of the lipoprotein on the bacterial surface was minimal. A monoclonal antibody raised to the 32-kDa lipoprotein of S. aureus was used in immunoblotting studies to investigate the conservation of this antigen among a variety of staphylococci. The monoclonal antibody reacted with polypeptides of 32 kDa in S. epidermidis and S. aureus and of 40 kDa in Staphylococcus hominis. No reactivity was detected with Staphylococcus lugdunensis, Staphylococcus cohni, or Staphylococcus haemolyticus. The gene encoding the 32-kDa lipoprotein from S. epidermidis has been isolated from a Lambda Zap II genomic DNA library and found to be a component of an <span class="hlt">iron</span>-regulated operon encoding a novel ABC-type <span class="hlt">transporter</span>. The operon contains three genes, designated sitA, -B, and -C, encoding an ATPase, a cytoplasmic membrane protein, and the 32-kDa lipoprotein, respectively. SitC shows significant homology both with a number of bacterial adhesins, including FimA of Streptococcus parasanguis and ScaA of Streptococcus gordonii, and with lipoproteins of a recently described family of ABC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26948158','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26948158"><span id="translatedtitle">Evolutionary analysis of <span class="hlt">iron</span> (Fe) acquisition <span class="hlt">system</span> in Marchantia polymorpha.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lo, Jing-Chi; Tsednee, Munkhtsetseg; Lo, Ying-Chu; Yang, Shun-Chung; Hu, Jer-Ming; Ishizaki, Kimitsune; Kohchi, Takayuki; Lee, Der-Chuen; Yeh, Kuo-Chen</p> <p>2016-07-01</p> <p>To acquire appropriate <span class="hlt">iron</span> (Fe), vascular plants have developed two unique strategies, the reduction-based strategy I of nongraminaceous plants for Fe(2+) and the chelation-based strategy II of graminaceous plants for Fe(3+) . However, the mechanism of Fe uptake in bryophytes, the earliest diverging branch of land plants and dominant in gametophyte generation is less clear. Fe isotope fractionation analysis demonstrated that the liverwort Marchantia polymorpha uses reduction-based Fe acquisition. Enhanced activities of ferric chelate reductase and proton ATPase were detected under Fe-deficient conditions. However, M. polymorpha did not show mugineic acid family phytosiderophores, the key components of strategy II, or the precursor nicotianamine. Five ZIP (ZRT/IRT-like protein) homologs were identified and speculated to be involved in Fe uptake in M. polymorpha. MpZIP3 knockdown conferred reduced growth under Fe-deficient conditions, and MpZIP3 overexpression increased Fe content under excess Fe. Thus, a nonvascular liverwort, M. polymorpha, uses strategy I for Fe acquisition. This <span class="hlt">system</span> may have been acquired in the common ancestor of land plants and coopted from the gametophyte to sporophyte generation in the evolution of land plants. PMID:26948158</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3751942','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3751942"><span id="translatedtitle">Identification and characterization of the zinc-regulated <span class="hlt">transporters</span>, <span class="hlt">iron</span>-regulated <span class="hlt">transporter</span>-like protein (ZIP) gene family in maize</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>Background Zinc (Zn) and <span class="hlt">iron</span> (Fe) are essential micronutrients for plant growth and development, their deficiency or excess severely impaired physiological and biochemical reactions of plants. Therefore, a tightly controlled zinc and <span class="hlt">iron</span> uptake and homeostasis network has been evolved in plants. The Zinc-regulated <span class="hlt">transporters</span>, <span class="hlt">Iron</span>-regulated <span class="hlt">transporter</span>-like Proteins (ZIP) are capable of uptaking and <span class="hlt">transporting</span> divalent metal ion and are suggested to play critical roles in balancing metal uptake and homeostasis, though a detailed analysis of ZIP gene family in maize is still lacking. Results Nine ZIP-coding genes were identified in maize genome. It was revealed that the ZmZIP proteins share a conserved transmembrane domain and a variable region between TM-3 and TM-4. Transiently expression in onion epidermal cells revealed that all ZmZIP proteins were localized to the endoplasmic reticulum and plasma membrane. The yeast complementation analysis was performed to test the Zn or Fe <span class="hlt">transporter</span> activity of ZmZIP proteins. Expression analysis showed that the ZmIRT1 transcripts were dramatically induced in response to Zn- and Fe-deficiency, though the expression profiles of other ZmZIP changed variously. The expression patterns of ZmZIP genes were observed in different stages of embryo and endosperm development. The accumulations of ZmIRT1 and ZmZIP6 were increased in the late developmental stages of embryo, while ZmZIP4 was up-regulated during the early development of embryo. In addition, the expression of ZmZIP5 was dramatically induced associated with middle stage development of embryo and endosperm. Conclusions These results suggest that ZmZIP genes encode functional Zn or Fe <span class="hlt">transporters</span> that may be responsible for the uptake, translocation, detoxification and storage of divalent metal ion in plant cells. The various expression patterns of ZmZIP genes in embryo and endosperm indicates that they may be essential for ion translocation and storage during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..GECKW3001T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..GECKW3001T"><span id="translatedtitle">Heavy particle <span class="hlt">transport</span> in sputtering <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trieschmann, Jan</p> <p>2015-09-01</p> <p>This contribution aims to discuss the theoretical background of heavy particle <span class="hlt">transport</span> in plasma sputtering <span class="hlt">systems</span> such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the <span class="hlt">transport</span> of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional <span class="hlt">transport</span> through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the <span class="hlt">transport</span> of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the <span class="hlt">transport</span> of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9803E..2YB','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9803E..2YB"><span id="translatedtitle">Hyperspectral range imaging for <span class="hlt">transportation</span> <span class="hlt">systems</span> evaluation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bridgelall, Raj; Rafert, J. B.; Atwood, Don; Tolliver, Denver D.</p> <p>2016-04-01</p> <p><span class="hlt">Transportation</span> agencies expend significant resources to inspect critical infrastructure such as roadways, railways, and pipelines. Regular inspections identify important defects and generate data to forecast maintenance needs. However, cost and practical limitations prevent the scaling of current inspection methods beyond relatively small portions of the network. Consequently, existing approaches fail to discover many high-risk defect formations. Remote sensing techniques offer the potential for more rapid and extensive non-destructive evaluations of the multimodal <span class="hlt">transportation</span> infrastructure. However, optical occlusions and limitations in the spatial resolution of typical airborne and space-borne platforms limit their applicability. This research proposes hyperspectral image classification to isolate <span class="hlt">transportation</span> infrastructure targets for high-resolution photogrammetric analysis. A plenoptic swarm of unmanned aircraft <span class="hlt">systems</span> will capture images with centimeter-scale spatial resolution, large swaths, and polarization diversity. The light field solution will incorporate structure-from-motion techniques to reconstruct three-dimensional details of the isolated targets from sequences of two-dimensional images. A comparative analysis of existing low-power wireless communications standards suggests an application dependent tradeoff in selecting the best-suited link to coordinate swarming operations. This study further produced a taxonomy of specific roadway and railway defects, distress symptoms, and other anomalies that the proposed plenoptic swarm sensing <span class="hlt">system</span> would identify and characterize to estimate risk levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860015926','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860015926"><span id="translatedtitle">An overview of European space <span class="hlt">transportation</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lo, R. E.</p> <p>1985-01-01</p> <p>With the completion of the launch rocket series Ariane 1 to 4, Europe will have reached the same capacity to <span class="hlt">transport</span> commercial payloads as the USA has with the Space Shuttle and the kick stages which are presently operative. The near term development of these capacities would require Europe to develop a larger launch rocket, Araine 5. Further motivations for this rocket are access to manned spaceflight, the development of an European space station, and the demand for shuttle technology. Shuttle technology is the subject of research being done in France on the winged re-entry vehicle Hermes. Operation of the European space station Columbus will require development of an interorbital <span class="hlt">transport</span> <span class="hlt">system</span> to facilitate traffic between the various segments of the space station. All European space <span class="hlt">transportation</span> <span class="hlt">systems</span> will have to match their quality to that of the other countries involve in space flight. All areas of development are marked not only by possible cooperation but also by increased competition because of increasing commercialization of space flight.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910007708','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910007708"><span id="translatedtitle">National Space <span class="hlt">Transportation</span> <span class="hlt">System</span> (NSTS) technology needs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Winterhalter, David L.; Ulrich, Kimberly K.</p> <p>1990-01-01</p> <p>The National Space <span class="hlt">Transportation</span> <span class="hlt">System</span> (NSTS) is one of the Nation's most valuable resources, providing manned <span class="hlt">transportation</span> to and from space in support of payloads and scientific research. The NSTS program is currently faced with the problem of hardware obsolescence, which could result in unacceptable schedule and cost impacts to the flight program. Obsolescence problems occur because certain components are no longer being manufactured or repair turnaround time is excessive. In order to achieve a long-term, reliable <span class="hlt">transportation</span> <span class="hlt">system</span> that can support manned access to space through 2010 and beyond, NASA must develop a strategic plan for a phased implementation of enhancements which will satisfy this long-term goal. The NSTS program has initiated the Assured Shuttle Availability (ASA) project with the following objectives: eliminate hardware obsolescence in critical areas, increase reliability and safety of the vehicle, decrease operational costs and turnaround time, and improve operational capability. The strategy for ASA will be to first meet the mandatory needs - keep the Shuttle flying. Non-mandatory changes that will improve operational capability and enhance performance will then be considered if funding is adequate. Upgrade packages should be developed to install within designated inspection periods, grouped in a systematic approach to reduce cost and schedule impacts, and allow the capability to provide a Block 2 Shuttle (Phase 3).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011tst..conf...38B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011tst..conf...38B"><span id="translatedtitle">Technological Support for Logistics <span class="hlt">Transportation</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bujak, Andrzej; Śliwa, Zdzisław; Gębczyńska, Alicja</p> <p></p> <p>The modern world is changing introducing robots, remotely controlled vehicles and other crewless means of <span class="hlt">transportation</span> to reduce people's mistakes, as the main cause of incidents and crashes during traffic. New technologies are supporting operators and drivers, and according to some studies they can even replace them. Such programs as: AHS, UAH, IVBSS or MTVR are under development to improve traffic flow and its safety, to reduce traffic hazards and crashes. It is necessary to analyze such concepts and implement them boldly, including Polish logistics' companies, new programs, highways' <span class="hlt">system</span> etc., as they will be applied in the future, so it is necessary to prepare logistics infrastructure ahead of time in order to capitalize on these improvements. The problem is quite urgent as <span class="hlt">transportation</span> in the country must not be outdated to meet clients' expectations and to keep pace with competing foreign companies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25939068','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25939068"><span id="translatedtitle">Development of a novel antimicrobial screening <span class="hlt">system</span> targeting the pyoverdine-mediated <span class="hlt">iron</span> acquisition <span class="hlt">system</span> and xenobiotic efflux pumps.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sato, Kazuki; Ushioda, Kenichi; Akiba, Keiji; Matsumoto, Yoshimi; Maseda, Hideaki; Ando, Tasuke; Isogai, Emiko; Nakae, Taiji; Yoneyama, Hiroshi</p> <p>2015-01-01</p> <p>The <span class="hlt">iron</span> acquisition <span class="hlt">systems</span> in Pseudomonas aeruginosa are inducible in response to low-<span class="hlt">iron</span> conditions and important for growth of this organism under <span class="hlt">iron</span> limitation. OprM is the essential outer membrane subunit of the MexAB-OprM xenobiotic efflux pump. We designed and constructed a new model antimicrobial screening <span class="hlt">system</span> targeting both the <span class="hlt">iron</span>-uptake <span class="hlt">system</span> and xenobiotic efflux pumps. The oprM gene was placed immediately downstream of the ferri-pyoverdine receptor gene, fpvA, in the host lacking chromosomal oprM and the expression of oprM was monitored by an antibiotic susceptibility test under <span class="hlt">iron</span> depleted and replete conditions. The recombinant cells showed wild-type susceptibility to pump substrate antibiotics, e.g., aztreonam, under <span class="hlt">iron</span> limitation and became supersusceptible to them under <span class="hlt">iron</span> repletion, suggesting that expression of oprM is under control of the <span class="hlt">iron</span> acquisition <span class="hlt">system</span>. Upon screening of a chemical library comprising 2952 compounds using this strain, a compound-ethyl 2-(1-acetylpiperidine-4-carboxamido)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate-was found to enhance the efficacy of aztreonam under <span class="hlt">iron</span> limitation, suggesting that the compound inhibits either the <span class="hlt">iron</span> acquisition <span class="hlt">system</span> or the MexAB-OprM efflux pump. This compound was subsequently found to inhibit the growth of wild-type cells in the presence of sublethal amounts of aztreonam, regardless of the presence or absence of dipyridyl, an <span class="hlt">iron</span>-chelator. The compound was eventually identified to block the function of the MexAB-OprM efflux pump, showing the validity of this new method. PMID:25939068</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26291756','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26291756"><span id="translatedtitle">Kinetic modeling of pH-dependent antimony (V) sorption and <span class="hlt">transport</span> in <span class="hlt">iron</span> oxide-coated sand.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cai, Yongbing; Li, Lulu; Zhang, Hua</p> <p>2015-11-01</p> <p>Understanding the mechanisms and kinetics controlling the retention and <span class="hlt">transport</span> of antimony (Sb) is prerequisite for evaluating the risk of groundwater contamination by the toxic element. In this study, kinetic batch and saturated miscible displacement experiments were performed to investigate effects of protonation-deprotonation reactions on sorption-desorption and <span class="hlt">transport</span> of Sb(V) in <span class="hlt">iron</span> oxide-coated sand (IOCS). Results clearly demonstrated that Sb(V) sorption was highly nonlinear and time dependent, where both sorption capacity and kinetic rates decreased with increasing solution pH. Breakthrough curves (BTCs) obtained at different solution pH exhibited that mobility of Sb(V) were higher under neutral to alkaline condition than under acidic condition. Because of the nonlinear and non-equilibrium nature of Sb(V) retention and <span class="hlt">transport</span>, multi-reaction models (MRM) with equilibrium and kinetic sorption expressions were utilized successfully to simulate the experiment data. Equilibrium distribution coefficient (Ke) and reversible kinetic retention parameters (k1 and k2) of both kinetic sorption and <span class="hlt">transport</span> experiment showed marked decrease as pH increased from 4.0 to 7.5. Surface complexation is suggested as the dominant mechanism for the observed pH-dependent phenomena, which need to be incorporated into the kinetic models to accurately simulate the reactive <span class="hlt">transport</span> of Sb(V) in vadose zone and aquifers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/842118','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/842118"><span id="translatedtitle">Design of Large Momentum Acceptance <span class="hlt">Transport</span> <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>D.R. Douglas</p> <p>2005-05-01</p> <p>The use of energy recovery to enable high power linac operation often gives rise to an attendant challenge--the <span class="hlt">transport</span> of high power beams subtending large phase space volumes. In particular applications--such as FEL driver accelerators--this manifests itself as a requirement for beam <span class="hlt">transport</span> <span class="hlt">systems</span> with large momentum acceptance. We will discuss the design, implementation, and operation of such <span class="hlt">systems</span>. Though at times counterintuitive in behavior (perturbative descriptions may, for example, be misleading), large acceptance <span class="hlt">systems</span> have been successfully utilized for generations as spectrometers and accelerator recirculators [1]. Such <span class="hlt">systems</span> are in fact often readily designed using appropriate geometric descriptions of beam behavior; insight provided using such a perspective may in addition reveal inherent symmetries that simplify construction and improve operability. Our discussion will focus on two examples: the Bates-clone recirculator used in the Jefferson Lab 10 kW IR U pgrade FEL (which has an observed acceptance of 10% or more) and a compaction-managed mirror-bend achromat concept with an acceptance ranging from 50 to 150 MeV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004PhDT.......187H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004PhDT.......187H"><span id="translatedtitle">Electrodeposition of <span class="hlt">iron</span>-cobalt-nickel-copper quaternary <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Qiang</p> <p></p> <p>Electrodeposition is a cost-effective method to produce thin film materials, which have been used widely in the microelectronic industry, and is advantageous to fabricate metal deposits into recessed and curved areas. In this dissertation, a FeCoNiCu quaternary alloy <span class="hlt">system</span> was investigated, both experimentally and theoretically, for fabrication of multilayers, grating structures, and nanowires. Multilayer structures are composed of alternating ferromagnetic and nonmagnetic nanometric layers, and are of interest due to the giant magnetoresistance (GMR) property it possesses, a change in electric resistance in the presence of an external magnetic field. In addition, the compositional modulation, or the composition contrast, in multilayer structures can be used to develop a grating structured mold for the development of a novel nanoimprinting process. FeCoNiCu was investigated as a more general alloy <span class="hlt">system</span> containing <span class="hlt">iron</span>-group metals and a nonmagnetic element, Cu, which can be simplified and adapted to any binary or ternary <span class="hlt">systems</span>. With a dilute tartrate sulfate bath nanometric multilayers were successfully fabricated with pulse plating and GMR value was reported for this electrodeposited <span class="hlt">system</span> for the first time. A value of -6% was achieved on rotating disk electrode (RDE) and this maximum occurred when the structure had no preferred crystal phase. Over 40% GMR has been achieved when the multilayer was plated onto a polycrystalline Cu foil. A mathematical model was developed to tailor the deposition process on RDE, and both steady state and nonsteady state cases were simulated. A compositional gradient, which is inherent to a nonsteady state deposition process when the layer size is of nanometer scale was predicted. The quaternary <span class="hlt">system</span> was explored for other applications. Selective etching of electrodeposited multilayer structures was investigated for different etching solutions. A diluted K2Cr2O 7/H2SO4 solution was successfully developed to produce grating</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018889','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018889"><span id="translatedtitle">Reactive solute <span class="hlt">transport</span> in an acidic stream: Experimental pH increase and simulation of controls on pH, aluminum, and <span class="hlt">iron</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Broshears, R.E.; Runkel, R.L.; Kimball, B.A.; McKnight, Diane M.; Bencala, K.E.</p> <p>1996-01-01</p> <p>Solute <span class="hlt">transport</span> simulations quantitatively constrained hydrologic and geochemical hypotheses about field observations of a pH modification in an acid mine drainage stream. Carbonate chemistry, the formation of solid phases, and buffering interactions with the stream bed were important factors in explaining the behavior of pH, aluminum, and <span class="hlt">iron</span>. The precipitation of microcrystalline gibbsite accounted for the behavior of aluminum; precipitation of Fe(OH)3 explained the general pattern of <span class="hlt">iron</span> solubility. The dynamic experiment revealed limitations on assumptions that reactions were controlled only by equilibrium chemistry. Temporal variation in relative rates of photoreduction and oxidation influenced <span class="hlt">iron</span> behavior. Kinetic limitations on ferrous <span class="hlt">iron</span> oxidation and hydrous oxide precipitation and the effects of these limitations on field filtration were evident. Kinetic restraints also characterized interaction between the water column and the stream bed, including sorption and desorption of protons from <span class="hlt">iron</span> oxides at the sediment-water interface and post-injection dissolution of the precipitated aluminum solid phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25063698','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25063698"><span id="translatedtitle">Guar gum solutions for improved delivery of <span class="hlt">iron</span> particles in porous media (part 2): <span class="hlt">iron</span> <span class="hlt">transport</span> tests and modeling in radial geometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tosco, Tiziana; Gastone, Francesca; Sethi, Rajandrea</p> <p>2014-10-01</p> <p>In the present work column <span class="hlt">transport</span> tests were performed in order to study the mobility of guar-gum suspensions of microscale zero-valent <span class="hlt">iron</span> particles (MZVI) in porous media. The results were analyzed with the purpose of implementing a radial model for the design of full scale interventions. The <span class="hlt">transport</span> tests were performed using several concentrations of shear thinning guar gum solutions as stabilizer (1.5, 3 and 4g/l) and applying different flow rates (Darcy velocity in the range 1·10(-4) to 2·10(-3)m/s), representative of different distances from the injection point in the radial domain. Empirical relationships, expressing the dependence of the deposition and release parameters on the flow velocity, were derived by inverse fitting of the column <span class="hlt">transport</span> tests using a modified version of E-MNM1D (Tosco and Sethi, 2010) and the user interface MNMs (www.polito.it/groundwater/software). They were used to develop a comprehensive <span class="hlt">transport</span> model of MZVI suspensions in radial coordinates, called E-MNM1R, which takes into account the non Newtonian (shear thinning) rheological properties of the dispersant fluid and the porous medium clogging associated with filtration and sedimentation in the porous medium of both MZVI and guar gum residual undissolved particles. The radial model was run in forward mode to simulate the injection of MZVI dispersed in guar gum in conditions similar to those applied in the column <span class="hlt">transport</span> tests. In a second stage, we demonstrated how the model can be used as a valid tool for the design and the optimization of a full scale intervention. The simulation results indicated that several concurrent aspects are to be taken into account for the design of a successful delivery of MZVI/guar gum slurries via permeation injection, and a compromise is necessary between maximizing the radius of influence of the injection and minimizing the injection pressure, to guarantee a sufficiently homogeneous distribution of the particles around the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19539055','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19539055"><span id="translatedtitle">Responsiveness of Trichomonas vaginalis to <span class="hlt">iron</span> concentrations: evidence for a post-transcriptional <span class="hlt">iron</span> regulation by an IRE/IRP-like <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Torres-Romero, J C; Arroyo, R</p> <p>2009-12-01</p> <p>Trichomonas vaginalis has high <span class="hlt">iron</span>-dependency, favoring its growth and multiplication in culture. <span class="hlt">Iron</span> also regulates some of the trichomonal virulence properties by yet unknown mechanisms. <span class="hlt">Iron</span> is an essential but potentially toxic metal for the majority of organisms. Thus, its concentration must be tightly regulated within the cell. In mammals, the <span class="hlt">iron</span> homeostasis is mainly regulated at the post-transcriptional level by a well known mechanism mediated by the binding of <span class="hlt">iron</span> regulatory proteins (IRP1 and IRP2) to hairpin-loop structures, dubbed <span class="hlt">iron</span>-responsive elements (IREs), localized in the untranslated regions (UTRs) of target mRNAs. The knowledge of <span class="hlt">iron</span> regulation in T. vaginalis is still very limited. An <span class="hlt">iron</span>-responsive promoter and other regulatory elements in the 5'-UTR of the ap65-1 gene were identified as a mechanism for the positive transcriptional regulation of trichomonad genes by <span class="hlt">iron</span>. Recently, two IRE-like hairpin-loop structures in mRNAs of differentially <span class="hlt">iron</span>-regulated TVCP4 and TVCP12 cysteine proteinases, as well as IRP-like trichomonad proteins were identified in T. vaginalis, suggesting the existence in this protozoan of a post-transcriptional <span class="hlt">iron</span> regulatory mechanism by an IRE/IRP-like <span class="hlt">system</span>. The responsiveness of T. vaginalis to distinct <span class="hlt">iron</span> concentrations was examined here. Also, the comparison of the atypical IRE-like sequences of T. vaginalis with the consensus IRE and other putative IRE sequences present in parasite and bacteria mRNAs suggest that these trichomonad IRE-like sequences might be the ancestral forms of the RNA stem-loop structures of the IRE/IRP <span class="hlt">system</span>. PMID:19539055</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19539055','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19539055"><span id="translatedtitle">Responsiveness of Trichomonas vaginalis to <span class="hlt">iron</span> concentrations: evidence for a post-transcriptional <span class="hlt">iron</span> regulation by an IRE/IRP-like <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Torres-Romero, J C; Arroyo, R</p> <p>2009-12-01</p> <p>Trichomonas vaginalis has high <span class="hlt">iron</span>-dependency, favoring its growth and multiplication in culture. <span class="hlt">Iron</span> also regulates some of the trichomonal virulence properties by yet unknown mechanisms. <span class="hlt">Iron</span> is an essential but potentially toxic metal for the majority of organisms. Thus, its concentration must be tightly regulated within the cell. In mammals, the <span class="hlt">iron</span> homeostasis is mainly regulated at the post-transcriptional level by a well known mechanism mediated by the binding of <span class="hlt">iron</span> regulatory proteins (IRP1 and IRP2) to hairpin-loop structures, dubbed <span class="hlt">iron</span>-responsive elements (IREs), localized in the untranslated regions (UTRs) of target mRNAs. The knowledge of <span class="hlt">iron</span> regulation in T. vaginalis is still very limited. An <span class="hlt">iron</span>-responsive promoter and other regulatory elements in the 5'-UTR of the ap65-1 gene were identified as a mechanism for the positive transcriptional regulation of trichomonad genes by <span class="hlt">iron</span>. Recently, two IRE-like hairpin-loop structures in mRNAs of differentially <span class="hlt">iron</span>-regulated TVCP4 and TVCP12 cysteine proteinases, as well as IRP-like trichomonad proteins were identified in T. vaginalis, suggesting the existence in this protozoan of a post-transcriptional <span class="hlt">iron</span> regulatory mechanism by an IRE/IRP-like <span class="hlt">system</span>. The responsiveness of T. vaginalis to distinct <span class="hlt">iron</span> concentrations was examined here. Also, the comparison of the atypical IRE-like sequences of T. vaginalis with the consensus IRE and other putative IRE sequences present in parasite and bacteria mRNAs suggest that these trichomonad IRE-like sequences might be the ancestral forms of the RNA stem-loop structures of the IRE/IRP <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MAR.M1163S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MAR.M1163S"><span id="translatedtitle">Chemically generated convective <span class="hlt">transport</span> in microfluidic <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shklyaev, Oleg; Das, Sambeeta; Altemose, Alicia; Shum, Henry; Balazs, Anna; Sen, Ayusman</p> <p></p> <p>High precision manipulation of small volumes of fluid, containing suspended micron sized objects like cells, viruses, and large molecules, is one of the main goals in designing modern lab-on-a-chip devices which can find a variety of chemical and biological applications. To <span class="hlt">transport</span> the cargo toward sensing elements, typical microfluidic devices often use pressure driven flows. Here, we propose to use enzymatic chemical reactions which decompose reagent into less dense products and generate flows that can <span class="hlt">transport</span> particles. Density variations that lead to flow in the assigned direction are created between the place where reagent is fed into the solution and the location where it is decomposed by enzymes attached to the surface of the microchannel. When the reagent is depleted, the fluid motion stops and particles sediment to the bottom. We demonstrate how the choice of chemicals, leading to specific reaction rates, can affect the <span class="hlt">transport</span> properties. In particular, we show that the intensity of the fluid flow, the final location of cargo, and the time for cargo delivery are controlled by the amount and type of reagent in the <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/933879','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/933879"><span id="translatedtitle">[A flavinogenic mutant of the yeast Pichia guilliermondii with impaired <span class="hlt">iron</span> <span class="hlt">transport</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shavlovskiĭ, G M; Fedorovich, D V; Zviagil'skais, R A</p> <p>1976-01-01</p> <p>A mutant of the yeast Pichia guilliermondii was produced by means of UV; the mutant was capable of riboflavin overproduction in the presence of high concentrations of <span class="hlt">iron</span> in the medium. The content of total and non-hemin <span class="hlt">iron</span> and cytochrome c, and the activity of catalase, were lower in the cells of the mutant than in the parent cells, while the activity of riboflavin synthetase was higher. The content of <span class="hlt">iron</span> in the cells increased when the mutant was cultivated on media with citric acid, siderochromes of Klebsiella aerogenes, Neurospora crassa, Rhodotorula glutinis, cultural broth of Pichia ohmeri, and autolysate of brewer's yeast, whereas the flavinogenous activity of the cells decreased. Rotenone inhibited respiration of the intact cells of the mutant producing elevated amounts of riboflavin; therefore, flavinogenesis was not regulated by non-hemin <span class="hlt">iron</span> on the first segment of the respiratory chain. Overproduction of riboflavin in the mutant of Pichia guilliermondii was proved to be a recessive property. PMID:933879</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/304002','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/304002"><span id="translatedtitle"><span class="hlt">Transportable</span> vitrification <span class="hlt">system</span> demonstration on mixed waste. Revision 1</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zamecnik, J.R.; Whitehouse, J.C.; Wilson, C.N.; Van Ryn, F.R.</p> <p>1998-04-22</p> <p>The <span class="hlt">Transportable</span> Vitrification <span class="hlt">System</span> (TVS) is a large scale, fully integrated, vitrification <span class="hlt">system</span> for the treatment of low-level and mixed wastes in the form of sludges, soils, incinerator ash, and many other waste streams. It was demonstrated on surrogate waste at Clemson University and at the Oak Ridge Reservation (ORR) prior to treating actual mixed waste. Treatment of a combination of dried B and C Pond sludge and CNF sludge was successfully demonstrated at ORR in 1997. The demonstration produced 7,616 kg of glass from 7,328 kg of mixed wastes with a 60% reduction in volume. Glass formulations for the wastes treated were developed using a combination of laboratory crucible studies with the actual wastes and small melter studies at Clemson with both surrogate and actual wastes. Initial characterization of the B and C Pond sludge had not shown the presence of carbon or fluoride, which required a modified glass formulation be developed to maintain proper glass redox and viscosity. The CNF sludge challenges the glass formulations due to high levels of phosphate and <span class="hlt">iron</span>. The demonstration was delayed several times by permitting problems, a glass leak, and electrical problems. The demonstration showed that the two wastes could be successfully vitrified, although the design glass production rate was not achieved. The glass produced met the Universal Treatment Standards and the emissions from the TVS were well within the allowable permit limits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS24E..06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS24E..06F"><span id="translatedtitle">Distal <span class="hlt">transport</span> of hydrothermal <span class="hlt">iron</span> in the deep Eastern South Pacific Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fitzsimmons, J. N.; Jenkins, W. J.; Lee, J.; Kayser, R. A.; Boyle, E. A.</p> <p>2012-12-01</p> <p>While dust deposition and <span class="hlt">transport</span> from continental margin sediments are usually thought to be the main inputs of <span class="hlt">iron</span> to the surface ocean dissolved Fe (dFe) pool, Fe input to the deep ocean has been attributed mostly to remineralization of sinking biogenic particles. Hydrothermal vents are known to emit large amounts of Fe to the deep ocean, but most of this Fe precipitates near the ridge crest, so it is not clear that vents supply a significant amount of dFe to the deep ocean. Several recent studies have seen dFe maxima in the deep ocean near ridge crests and attributed this dFe to hydrothermal activity (Boyle & Jenkins, 2008; Klunder et al. 2011; Wu et al. 2011; Klunder et al. 2012; Noble et al. 2012). Hydrothermally-derived Fe is believed to be maintained in the dissolved phase by a combination of binding by organic ligands (Bennett et al. 2008; Sander & Koschinsky, 2012) and a nanoparticle/colloidal contribution to the dFe class (Yucel et al. 2011). Modeling efforts using the distribution of excess He-3 in deep waters arising from hydrothermal activity have predicted that deep ocean dFe may be much higher than currently believed, especially in the southern hemisphere (Tagliabue et al. 2010). In this presentation, we show the first deep ocean dFe data from two stations in the Eastern South Pacific Ocean (Station 7 at 26.3degS, 104degW and Station 4 at 23.5degS, 88.8degW). He-3 and dissolved manganese (dMn) distributions at these stations imply that hydrothermal activity is a significant source of dFe to the deep ocean in this region. Maximum deep dFe concentrations at 2250m reach 1.5 nmol/kg at Station 7 and are still 0.86 nmol/kg at Station 4, thousands of kilometers from presumed East Pacific Rise hydrothermal sources. Excess He-3 and dFe are correlated in the plume maximum by comparison of the measured dFe with nearby WOCE He-3 stations spatially interpolated on isopycnals. We observe a slope of 1.1-2.0 x 10^6 mol Fe/mol He-3, similar to but somewhat</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992STICA..12..353K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992STICA..12..353K"><span id="translatedtitle">Saenger space <span class="hlt">transportation</span> <span class="hlt">system</span> - Progress report</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koelle, Dietrich E.; Kuczera, Heribert</p> <p>1992-10-01</p> <p>The first part of the Saenger <span class="hlt">System</span> Definition Study within the German National Hypersonics Technology Program (1988 to 1992) was completed by mid-1990. This paper summarizes the progress made and the status of the project as of that milestone which was formally completed by the <span class="hlt">System</span> Study Presentation in July 1990. For the second phase of the study (mid-1990 to end 1992) the original philosophy of different upper stages for manned space operations and for unmanned cargo/payloads <span class="hlt">transportation</span> is being maintained, however, a winged unmanned Horus-C version has been found to be a better solution than the originally conceived expendable ballistic stage Cargus. The advantage of this twin-Horus Concept is the greater commonality of both upper stages as well as the new return capability of payloads up to 7 Mg. The maximum payload capability of the expendable stage was of course higher, but it is assumed that for larger payloads a complementary launch vehicle (i.e. Ariane 5) will be further available. The paper also presents new data about the Horus return flight trajectories as well as on the aerothermodynamic studies and experimental work. Finally, aspects of mission operations and economics are discussed which are of special importance for such an advanced reusable space <span class="hlt">transportation</span> <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5015096','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5015096"><span id="translatedtitle">Involvement of type VI secretion <span class="hlt">system</span> in secretion of <span class="hlt">iron</span> chelator pyoverdine in Pseudomonas taiwanensis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chen, Wen-Jen; Kuo, Tzu-Yen; Hsieh, Feng-Chia; Chen, Pi-Yu; Wang, Chang-Sheng; Shih, Yu-Ling; Lai, Ying-Mi; Liu, Je-Ruei; Yang, Yu-Liang; Shih, Ming-Che</p> <p>2016-01-01</p> <p>Rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive rice diseases worldwide. Therefore, in addition to breeding disease-resistant rice cultivars, it is desirable to develop effective biocontrol agents against Xoo. Here, we report that a soil bacterium Pseudomonas taiwanensis displayed strong antagonistic activity against Xoo. Using matrix-assisted laser desorption/ionization imaging mass spectrometry, we identified an <span class="hlt">iron</span> chelator, pyoverdine, secreted by P. taiwanensis that could inhibit the growth of Xoo. Through Tn5 mutagenesis of P. taiwanensis, we showed that mutations in genes that encode components of the type VI secretion <span class="hlt">system</span> (T6SS) as well as biosynthesis and maturation of pyoverdine resulted in reduced toxicity against Xoo. Our results indicated that T6SS is involved in the secretion of endogenous pyoverdine. Mutations in T6SS component genes affected the secretion of mature pyoverdine from the periplasmic space into the extracellular medium after pyoverdine precursor is transferred to the periplasm by the inner membrane <span class="hlt">transporter</span> PvdE. In addition, we also showed that other export <span class="hlt">systems</span>, i.e., the PvdRT-OpmQ and MexAB-OprM efflux <span class="hlt">systems</span> (for which there have been previous suggestions of involvement) and the type II secretion <span class="hlt">system</span> (T2SS), are not involved in pyoverdine secretion. PMID:27605490</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27605490','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27605490"><span id="translatedtitle">Involvement of type VI secretion <span class="hlt">system</span> in secretion of <span class="hlt">iron</span> chelator pyoverdine in Pseudomonas taiwanensis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Wen-Jen; Kuo, Tzu-Yen; Hsieh, Feng-Chia; Chen, Pi-Yu; Wang, Chang-Sheng; Shih, Yu-Ling; Lai, Ying-Mi; Liu, Je-Ruei; Yang, Yu-Liang; Shih, Ming-Che</p> <p>2016-01-01</p> <p>Rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive rice diseases worldwide. Therefore, in addition to breeding disease-resistant rice cultivars, it is desirable to develop effective biocontrol agents against Xoo. Here, we report that a soil bacterium Pseudomonas taiwanensis displayed strong antagonistic activity against Xoo. Using matrix-assisted laser desorption/ionization imaging mass spectrometry, we identified an <span class="hlt">iron</span> chelator, pyoverdine, secreted by P. taiwanensis that could inhibit the growth of Xoo. Through Tn5 mutagenesis of P. taiwanensis, we showed that mutations in genes that encode components of the type VI secretion <span class="hlt">system</span> (T6SS) as well as biosynthesis and maturation of pyoverdine resulted in reduced toxicity against Xoo. Our results indicated that T6SS is involved in the secretion of endogenous pyoverdine. Mutations in T6SS component genes affected the secretion of mature pyoverdine from the periplasmic space into the extracellular medium after pyoverdine precursor is transferred to the periplasm by the inner membrane <span class="hlt">transporter</span> PvdE. In addition, we also showed that other export <span class="hlt">systems</span>, i.e., the PvdRT-OpmQ and MexAB-OprM efflux <span class="hlt">systems</span> (for which there have been previous suggestions of involvement) and the type II secretion <span class="hlt">system</span> (T2SS), are not involved in pyoverdine secretion. PMID:27605490</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930008858','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930008858"><span id="translatedtitle">Conceptual design of a Mars <span class="hlt">transportation</span> <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1992-01-01</p> <p>In conjunction with NASA Marshall Space Flight Center and several major aerospace corporations the University of Minnesota has developed a scenario to place humans on Mars by the year 2016. The project took the form of a year-long design course in the senior design curricula at the University's Aerospace Engineering and Mechanics Department. Students worked with the instructor, teaching assistants and engineers in industry to develop a vehicle and the associated mission profile to fulfill the requirements of the Mars <span class="hlt">Transportation</span> <span class="hlt">System</span>. This report is a summary of the final design and the process though which the final product was developed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880005617','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880005617"><span id="translatedtitle">A space <span class="hlt">transportation</span> <span class="hlt">system</span> operations model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morris, W. Douglas; White, Nancy H.</p> <p>1987-01-01</p> <p>Presented is a description of a computer program which permits assessment of the operational support requirements of space <span class="hlt">transportation</span> <span class="hlt">systems</span> functioning in both a ground- and space-based environment. The scenario depicted provides for the delivery of payloads from Earth to a space station and beyond using upper stages based at the station. Model results are scenario dependent and rely on the input definitions of delivery requirements, task times, and available resources. Output is in terms of flight rate capabilities, resource requirements, and facility utilization. A general program description, program listing, input requirements, and sample output are included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930020552','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930020552"><span id="translatedtitle">Mars integrated <span class="hlt">transportation</span> <span class="hlt">system</span> multistage Mars mission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1991-01-01</p> <p>In accordance with the objective of the Mars Integrated <span class="hlt">Transport</span> <span class="hlt">System</span> (MITS) program, the Multistage Mars Mission (MSMM) design team developed a profile for a manned mission to Mars. The purpose of the multistage mission is to send a crew of five astronauts to the martian surface by the year 2019. The mission continues man's eternal quest for exploration of new frontiers. This mission has a scheduled duration of 426 days that includes experimentation en route as well as surface exploration and experimentation. The MSMM is also designed as a foundation for a continuing program leading to the colonization of the planet Mars.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830024015','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830024015"><span id="translatedtitle">Space <span class="hlt">transportation</span> <span class="hlt">system</span> biomedical operations support study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>White, S. C.</p> <p>1983-01-01</p> <p>The shift of the Space <span class="hlt">Transportation</span> <span class="hlt">System</span> (STS) flight tests of the orbiter vehicle to the preparation and flight of the payloads is discussed. Part of this change is the transition of the medical and life sciences aspects of the STS flight operations to reflect the new state. The medical operations, the life sciences flight experiments support requirements and the intramural research program expected to be at KSC during the operational flight period of the STS and a future space station are analyzed. The adequacy of available facilities, plans, and resources against these future needs are compared; revisions and/or alternatives where appropriate are proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003IJTSM.123...63H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003IJTSM.123...63H"><span id="translatedtitle">Future Intelligent <span class="hlt">Transportation</span> <span class="hlt">Systems</span> and Sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hosaka, Akio</p> <p></p> <p>A road vehicle traffic contributes to the social improvement greatly, but it has big problems such as safety, congestion, environment, energy, elder people driving and adaptation to information society. ITS (Intelligent <span class="hlt">Transportation</span> <span class="hlt">Systems</span>) is expected as a direction solving these. The intellectual function about a road vehicle traffic depended on most of human beings. ITS helps intellectual functions such as information sensing, situation recognition, judgment, planning and operation. A sensor detecting information is an important key in ITS. I describe expectation to a sensor in ITS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19720029756&hterms=Cherry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCherry','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19720029756&hterms=Cherry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCherry"><span id="translatedtitle">Operating <span class="hlt">systems</span> in the air <span class="hlt">transportation</span> environment.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cherry, G. W.</p> <p>1971-01-01</p> <p>Consideration of the problems facing air <span class="hlt">transport</span> at present, and to be expected in the future. In the Northeast Corridor these problems involve community acceptance, airway and airport congestion and delays, passenger acceptance, noise reduction, and improvements in low-density short-haul economics. In the development of a superior short-haul operating <span class="hlt">system</span>, terminal-configured vs cruise-configured vehicles are evaluated. CTOL, STOL, and VTOL aircraft of various types are discussed. In the field of noise abatement, it is shown that flight procedural techniques are capable of supplementing ?quiet engine' technology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850015589','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850015589"><span id="translatedtitle">National Space <span class="hlt">Transportation</span> <span class="hlt">Systems</span> Program mission report</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Collins, M. A., Jr.; Aldrich, A. D.; Lunney, G. S.</p> <p>1984-01-01</p> <p>The STS 41-C National Space <span class="hlt">Transportation</span> <span class="hlt">Systems</span> Program Mission Report contains a summary of the major activities and accomplishments of the eleventh Shuttle flight and fifth flight of the OV-099 vehicle, Challenger. Also summarized are the significant problems that occurred during STS 41-C, and a problem tracking list that is a complete list of all problems that occurred during the flight. The major objectives of flight STS 41-C were to successfully deploy the LDEF (long duration exposure facility) and retrieve, repair and redeploy the SMM (Solar Maximum Mission) spacecraft, and perform functions of IMAX and Cinema 360 cameras.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810054727&hterms=fires+uncontrolled&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfires%2Buncontrolled','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810054727&hterms=fires+uncontrolled&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfires%2Buncontrolled"><span id="translatedtitle">Fireworthiness of <span class="hlt">transport</span> aircraft interior <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, J. A.; Kourtides, D. A.</p> <p>1981-01-01</p> <p>This paper presents an overview of certain aspects of the evaluation of the fireworthiness of <span class="hlt">transport</span> aircraft interiors. First, it addresses the key materials question concerning the effect of interior <span class="hlt">systems</span> on the survival of passengers and crew in the case of an uncontrolled fire. Second, it examines some technical opportunities that are available today through the modification of aircraft interior subsystem components, modifications that may reasonably by expected to provide improvements in aircraft fire safety. Cost and risk benefits still remain to be determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010LPICo1538.5636P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010LPICo1538.5636P"><span id="translatedtitle">Terrestrial <span class="hlt">Iron</span> Hot Springs as Analogs for Ancient Martian Hydrothermal <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parenteau, M. N.; Farmer, J. D.; Jahnke, L. L.; Cady, S. L.</p> <p>2010-04-01</p> <p>We have been studying a subaerial terrestrial <span class="hlt">iron</span> hot spring as an potential analog for hydrothermal <span class="hlt">systems</span> on Mars. In this multidisciplinary study, we have characterized the aqueous geochemistry, mineralogy, and microbial biosignatures at Chocolate Pots hot springs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1007864','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1007864"><span id="translatedtitle">Mechanisms of <span class="hlt">iron</span> oxide transformation in hydrothermal <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Otake, Tsubasa; Wesolowski, David J; Anovitz, Lawrence {Larry} M</p> <p>2010-11-01</p> <p>Coexistence of magnetite and hematite in hydrothermal <span class="hlt">systems</span> has often been used to constrain the redox potential of fluids, assuming that the redox equilibrium is attained among all minerals and aqueous species. However, as temperature decreases, disequilibrium mineral assemblages may occur due to the slow kinetics of reaction involving the minerals and fluids. In this study, we conducted a series of experiments in which hematite or magnetite was reacted with an acidic solution under H{sub 2}-rich hydrothermal conditions (T = 100-250 C, P{sub H{sub 2}} = 0.05-5 MPa) to investigate the kinetics of redox and non-redox transformations between hematite and magnetite, and the mechanisms of <span class="hlt">iron</span> oxide transformation under hydrothermal conditions. The formation of euhedral crystals of hematite in 150 and 200 C experiments, in which magnetite was used as the starting material, indicates that non-redox transformation of magnetite to hematite occurred within 24 h. The chemical composition of the experimental solutions was controlled by the non-redox transformation between magnetite and hematite throughout the experiments. While solution compositions were controlled by the non-redox transformation in the first 3 days in a 250 C experiment, reductive dissolution of magnetite became important after 5 days and affected the solution chemistry. At 100 C, the presence of maghemite was indicated in the first 7 days. Based on these results, equilibrium constants of non-redox transformation between magnetite and hematite and those of non-redox transformation between magnetite and maghemite were calculated. Our results suggest that the redox transformation of hematite to magnetite occurs in the following steps: (1) reductive dissolution of hematite to Fe{sub (aq)}{sup 2+} and (2) non-redox transformation of hematite and Fe{sub (aq)}{sup 2+} to magnetite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1021991','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1021991"><span id="translatedtitle">Mechanisms of <span class="hlt">iron</span> oxide transformations in hydrothermal <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Otake, Tsubasa; Wesolowski, David J; Anovitz, Lawrence {Larry} M; Allard Jr, Lawrence Frederick; Ohmoto, Hiroshi</p> <p>2010-01-01</p> <p>Coexistence of magnetite and hematite in hydrothermal <span class="hlt">systems</span> has often been used to constrain the redox potential of fluids, assuming that the redox equilibrium is attained among all minerals and aqueous species. However, as temperature decreases, disequilibrium mineral assemblages may occur due to the slow kinetics of reaction involving the minerals and fluids. In this study, we conducted a series of experiments in which hematite or magnetite was reacted with an acidic solution under H2-rich hydrothermal conditions (T = 100 250 C,) to investigate the kinetics of redox and non-redox transformations between hematite and magnetite, and the mechanisms of <span class="hlt">iron</span> oxide transformation under hydrothermal conditions. The formation of euhedral crystals of hematite in 150 and 200 C experiments, in which magnetite was used as the starting material, indicates that non-redox transformation of magnetite to hematite occurred within 24 h. The chemical composition of the experimental solutions was controlled by the non-redox transformation between magnetite and hematite throughout the experiments. While solution compositions were controlled by the non-redox transformation in the first 3 days in a 250 C experiment, reductive dissolution of magnetite became important after 5 days and affected the solution chemistry. At 100 C, the presence of maghemite was indicated in the first 7 days. Based on these results, equilibrium constants of non-redox transformation between magnetite and hematite and those of non-redox transformation between magnetite and maghemite were calculated. Our results suggest that the redox transformation of hematite to magnetite occurs in the following steps: (1) reductive dissolution of hematite to and (2) non-redox transformation of hematite and to magnetite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/97260','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/97260"><span id="translatedtitle">Third-order <span class="hlt">TRANSPORT</span>: A computer program for designing charged particle beam <span class="hlt">transport</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Carey, D.C.; Brown, K.L.; Rothacker, F.</p> <p>1995-05-01</p> <p><span class="hlt">TRANSPORT</span> has been in existence in various evolutionary versions since 1963. The present version of <span class="hlt">TRANSPORT</span> is a first-, second-, and third-order matrix multiplication computer program intended for the design of static-magnetic beam <span class="hlt">transport</span> <span class="hlt">systems</span>. This report discusses the following topics on <span class="hlt">TRANSPORT</span>: Mathematical formulation of <span class="hlt">TRANSPORT</span>; input format for <span class="hlt">TRANSPORT</span>; summaries of <span class="hlt">TRANSPORT</span> elements; preliminary specifications; description of the beam; physical elements; other transformations; assembling beam lines; operations; variation of parameters for fitting; and available constraints -- the FIT command.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3475125','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3475125"><span id="translatedtitle">Factors Influencing the Diversity of <span class="hlt">Iron</span> Uptake <span class="hlt">Systems</span> in Aquatic Microorganisms</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Desai, Dhwani K.; Desai, Falguni D.; LaRoche, Julie</p> <p>2012-01-01</p> <p><span class="hlt">Iron</span> (Fe) is an essential micronutrient for many processes in all living cells. Dissolved Fe (dFe) concentrations in the ocean are of the order of a few nM, and Fe is often a factor limiting primary production. Bioavailability of Fe in aquatic environments is believed to be primarily controlled through chelation by Fe-binding ligands. Marine microbes have evolved different mechanisms to cope with the scarcity of bioavailable dFe. Gradients in dFe concentrations and diversity of the Fe-ligand pool from coastal to open ocean waters have presumably imposed selection pressures that should be reflected in the genomes of microbial communities inhabiting the pelagic realm. We applied a hidden Markov model (HMM)-based search for proteins related to cellular <span class="hlt">iron</span> metabolism, and in particular those involved in Fe uptake mechanisms in 164 microbial genomes belonging to diverse taxa and occupying different aquatic niches. A multivariate statistical approach demonstrated that in phototrophic organisms, there is a clear influence of the ecological niche on the diversity of Fe uptake <span class="hlt">systems</span>. Extending the analyses to the metagenome database from the Global Ocean Sampling expedition, we demonstrated that the Fe uptake and homeostasis mechanisms differed significantly across marine niches defined by temperatures and dFe concentrations, and that this difference was linked to the distribution of microbial taxa in these niches. Using the dN/dS ratios (which signify the rate of non-synonymous mutations) of the nucleotide sequences, we identified that genes encoding for TonB, Ferritin, Ferric reductase, IdiA, ZupT, and Fe2+ <span class="hlt">transport</span> proteins FeoA and FeoB were evolving at a faster rate (positive selection pressure) while genes encoding ferrisiderophore, heme and Vitamin B12 uptake <span class="hlt">systems</span>, siderophore biosynthesis, and IsiA and IsiB were under purifying selection pressure (evolving slowly). PMID:23087680</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19432346','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19432346"><span id="translatedtitle">[Distribution of sediment <span class="hlt">iron</span> of the ditch <span class="hlt">system</span> in Sanjiang Plain, northeast China].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zou, Yuan-Chun; Lü, Xian-Guo; Jiang, Ming; Xi, Min</p> <p>2009-03-15</p> <p>The <span class="hlt">iron</span> distribution of the multi-level ditch <span class="hlt">system</span> (hair canal-field canal-lateral canal-branch canal-main canal) was studied through total <span class="hlt">iron</span> determination of the sediments (0-60 cm). The results showed that the mean concentration was (3.02 +/- 0.10) x 10(4) mg x kg(-1). Extremely significant difference was obseved between different ditch level (F = 6.261, p < 0.001), and the highest and the lowest concentration were present in the farmland lateral canal (3.71 x 10(4) mg x kg(-1)) and wetland canal (2.43 x 10(4) mg x kg(-1)), respectively. The difference of different sediment layers was not significant (F = 0.093, p = 0.693), while the <span class="hlt">iron</span> concentrations of 0-10 cm and 10-20 cm sediments were 51.96% and 62.22% higher than that of the natural wetland soil nearby, respectively. <span class="hlt">Iron</span> can transfer with the runoff in a certain extent, but it was not cumulated along the ditch <span class="hlt">system</span> with the largest cumulation location at the third level. The runoff containing <span class="hlt">iron</span> decreased gradully because of the wetland protection and climate change nowadays. The horizontal transfer of <span class="hlt">iron</span> along the ditch <span class="hlt">system</span> indicated the timing and intensity of <span class="hlt">iron</span> loss in the past since the canals were dredged. PMID:19432346</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21140891','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21140891"><span id="translatedtitle">Intracellular localization and subsequent redistribution of metal <span class="hlt">transporters</span> in a rat choroid plexus model following exposure to manganese or <span class="hlt">iron</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang Xueqian; Miller, David S.</p> <p>2008-07-15</p> <p>Confocal microscopy was used to investigate the effects of manganese (Mn) and <span class="hlt">iron</span> (Fe) exposure on the subcellular distribution of metal <span class="hlt">transporting</span> proteins, i.e., divalent metal <span class="hlt">transporter</span> 1 (DMT1), metal <span class="hlt">transporter</span> protein 1 (MTP1), and transferrin receptor (TfR), in the rat intact choroid plexus which comprises the blood-cerebrospinal fluid barrier. In control tissue, DMT1 was concentrated below the apical epithelial membrane, MTP1 was diffuse within the cytosol, and TfR was distributed in vesicles around nuclei. Following Mn or Fe treatment (1 and 10 {mu}M), the distribution of DMT1 was not affected. However, MTP1 and TfR moved markedly toward the apical pole of the cells. These shifts were abolished when microtubules were disrupted. Quantitative RT-PCR and Western blot analyses revealed a significant increase in mRNA and protein levels of TfR but not DMT1 and MTP1 after Mn exposure. These results suggest that early events in the tissue response to Mn or Fe exposure involve microtubule-dependent, intracellular trafficking of MTP1 and TfR. The intracellular trafficking of metal <span class="hlt">transporters</span> in the choroid plexus following Mn exposure may partially contribute to Mn-induced disruption in Fe homeostasis in the cerebrospinal fluid (CSF) following Mn exposure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780022053','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780022053"><span id="translatedtitle">A study of characteristics of intercity <span class="hlt">transportation</span> <span class="hlt">systems</span>. Phase 1: Definition of <span class="hlt">transportation</span> comparison methodology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>English, J. M.; Smith, J. L.; Lifson, M. W.</p> <p>1978-01-01</p> <p>The objectives of this study are: (1) to determine a unified methodological framework for the comparison of intercity passenger and freight <span class="hlt">transportation</span> <span class="hlt">systems</span>; (2) to review the attributes of existing and future <span class="hlt">transportation</span> <span class="hlt">systems</span> for the purpose of establishing measures of comparison. These objectives were made more specific to include: (1) development of a methodology for comparing long term <span class="hlt">transportation</span> trends arising from implementation of various R&D programs; (2) definition of value functions and attribute weightings needed for further <span class="hlt">transportation</span> goals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.738a2008S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.738a2008S"><span id="translatedtitle">Risk management model in road <span class="hlt">transport</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sakhapov, R. L.; Nikolaeva, R. V.; Gatiyatullin, M. H.; Makhmutov, M. M.</p> <p>2016-08-01</p> <p>The article presents the results of a study of road safety indicators that influence the development and operation of the <span class="hlt">transport</span> <span class="hlt">system</span>. Road safety is considered as a continuous process of risk management. Authors constructed a model that relates the social risks of a major road safety indicator - the level of motorization. The model gives a fairly accurate assessment of the level of social risk for any given level of motorization. Authors calculated the dependence of the level of socio-economic costs of accidents and injured people in them. The applicability of the concept of socio-economic damage is caused by the presence of a linear relationship between the natural and economic indicators damage from accidents. The optimization of social risk is reduced to finding the extremum of the objective function that characterizes the economic effect of the implementation of measures to improve safety. The calculations make it possible to maximize the net present value, depending on the costs of improving road safety, taking into account socio-economic damage caused by accidents. The proposed econometric models make it possible to quantify the efficiency of the <span class="hlt">transportation</span> <span class="hlt">system</span>, allow to simulate the change in road safety indicators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/674664','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/674664"><span id="translatedtitle">Innovative technology summary report: <span class="hlt">Transportable</span> vitrification <span class="hlt">system</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p></p> <p>1998-09-01</p> <p>At the end of the cold war, many of the Department of Energy`s (DOE`s) major nuclear weapons facilities refocused their efforts on finding technically sound, economic, regulatory compliant, and stakeholder acceptable treatment solutions for the legacy of mixed wastes they had produced. In particular, an advanced stabilization process that could effectively treat the large volumes of settling pond and treatment sludges was needed. Based on this need, DOE and its contractors initiated in 1993 the EM-50 sponsored development effort required to produce a deployable mixed waste vitrification <span class="hlt">system</span>. As a consequence, the <span class="hlt">Transportable</span> Vitrification <span class="hlt">System</span> (TVS) effort was undertaken with the primary requirement to develop and demonstrate the technology and associated facility to effectively vitrify, for compliant disposal, the applicable mixed waste sludges and solids across the various DOE complex sites. After 4 years of development testing with both crucible and pilot-scale melters, the TVS facility was constructed by Envitco, evaluated and demonstrated with surrogates, and then successfully <span class="hlt">transported</span> to the ORNL ETTP site and demonstrated with actual mixed wastes in the fall of 1997. This paper describes the technology, its performance, the technology applicability and alternatives, cost, regulatory and policy issues, and lessons learned.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1243322','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1243322"><span id="translatedtitle">Sensor <span class="hlt">system</span> for fuel <span class="hlt">transport</span> vehicle</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Earl, Dennis Duncan; McIntyre, Timothy J.; West, David L.</p> <p>2016-03-22</p> <p>An exemplary sensor <span class="hlt">system</span> for a fuel <span class="hlt">transport</span> vehicle can comprise a fuel marker sensor positioned between a fuel storage chamber of the vehicle and an access valve for the fuel storage chamber of the vehicle. The fuel marker sensor can be configured to measure one or more characteristics of one or more fuel markers present in the fuel adjacent the sensor, such as when the marked fuel is unloaded at a retail station. The one or more characteristics can comprise concentration and/or identity of the one or more fuel markers in the fuel. Based on the measured characteristics of the one or more fuel markers, the sensor <span class="hlt">system</span> can identify the fuel and/or can determine whether the fuel has been adulterated after the marked fuel was last measured, such as when the marked fuel was loaded into the vehicle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900002420','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900002420"><span id="translatedtitle"><span class="hlt">Transport</span> <span class="hlt">systems</span> research vehicle color display <span class="hlt">system</span> operations manual</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Easley, Wesley C.; Johnson, Larry E.</p> <p>1989-01-01</p> <p>A recent upgrade of the <span class="hlt">Transport</span> <span class="hlt">Systems</span> Research Vehicle operated by the Advanced <span class="hlt">Transport</span> Operating <span class="hlt">Systems</span> Program Office at the NASA Langley Research Center has resulted in an all-glass panel in the research flight deck. Eight ARINC-D size CRT color displays make up the panel. A major goal of the display upgrade effort was ease of operation and maintenance of the hardware while maintaining versatility needed for flight research. Software is the key to this required versatility and will be the area demanding the most detailed technical design expertise. This document is is intended to serve as a single source of quick reference information needed for routine operation and <span class="hlt">system</span> level maintenance. Detailed maintenance and modification of the display <span class="hlt">system</span> will require specific design documentation and must be accomplished by individuals with specialized knowledge and experience.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=179080','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=179080"><span id="translatedtitle">Heme compounds as <span class="hlt">iron</span> sources for nonpathogenic Rhizobium bacteria.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Noya, F; Arias, A; Fabiano, E</p> <p>1997-01-01</p> <p>Many animal-pathogenic bacteria can use heme compounds as <span class="hlt">iron</span> sources. Like these microorganisms, rhizobium strains interact with host organisms where heme compounds are available. Results presented in this paper indicate that the use of hemoglobin as an <span class="hlt">iron</span> source is not restricted to animal-pathogenic microorganisms. We also demonstrate that heme, hemoglobin, and leghemoglobin can act as <span class="hlt">iron</span> sources under <span class="hlt">iron</span>-depleted conditions for Rhizobium meliloti 242. Analysis of <span class="hlt">iron</span> acquisition mutant strains indicates that siderophore-, heme-, hemoglobin-, and leghemoglobin-mediated <span class="hlt">iron</span> <span class="hlt">transport</span> <span class="hlt">systems</span> expressed by R. meliloti 242 share at least one component. PMID:9139934</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760004909','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760004909"><span id="translatedtitle">Air support facilities. [interface between air and surface <span class="hlt">transportation</span> <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1975-01-01</p> <p>Airports are discussed in terms of the interface between the ground and air for <span class="hlt">transportation</span> <span class="hlt">systems</span>. The classification <span class="hlt">systems</span>, design, facilities, administration, and operations of airports are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3623912','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3623912"><span id="translatedtitle">“Conjugate Channeling” Effect in Dislocation Core Diffusion: Carbon <span class="hlt">Transport</span> in Dislocated BCC <span class="hlt">Iron</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ishii, Akio; Li, Ju; Ogata, Shigenobu</p> <p>2013-01-01</p> <p>Dislocation pipe diffusion seems to be a well-established phenomenon. Here we demonstrate an unexpected effect, that the migration of interstitials such as carbon in <span class="hlt">iron</span> may be accelerated not in the dislocation line direction , but in a conjugate diffusion direction. This accelerated random walk arises from a simple crystallographic channeling effect. is a function of the Burgers vector b, but not , thus a dislocation loop possesses the same everywhere. Using molecular dynamics and accelerated dynamics simulations, we further show that such dislocation-core-coupled carbon diffusion in <span class="hlt">iron</span> has temperature-dependent activation enthalpy like a fragile glass. The 71° mixed dislocation is the only case in which we see straightforward pipe diffusion that does not depend on dislocation mobility. PMID:23593255</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27112517','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27112517"><span id="translatedtitle"><span class="hlt">Iron</span> <span class="hlt">transport</span> across the skin and gut epithelia of Pacific hagfish: Kinetic characterisation and effect of hypoxia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Glover, Chris N; Niyogi, Som; Blewett, Tamzin A; Wood, Chris M</p> <p>2016-09-01</p> <p>In most animals, the acquisition of the essential trace metal <span class="hlt">iron</span> (Fe) is achieved by the gut, but in hagfishes, the skin is a nutrient absorbing epithelium, and thus may also play a role in Fe uptake. In the current study, the absorption of Fe, as Fe(II), across the intestinal and cutaneous epithelia of Pacific hagfish (Eptatretus cirrhatus) was investigated. Both epithelia absorbed Fe, with saturation at lower tested concentrations, superseded by a diffusive component at higher Fe exposure concentrations. Affinity constants (Km) of 9.4 and 137μM, and maximal Fe <span class="hlt">transport</span> rates (Jmax) of 0.81 and 0.57nmolcm(-2)h(-1) were determined for the skin and the gut, respectively. This characterises the skin as a relatively high-affinity Fe <span class="hlt">transport</span> epithelium. The majority of the absorbed Fe in the skin remained in the tissue, whereas in the gut, most absorbed Fe was found in the serosal fluid, suggesting distinct mechanisms of Fe handling between the two epithelia. To determine if reduced dissolved oxygen altered Fe <span class="hlt">transport</span>, hagfish were subjected to hypoxia for 24h, before Fe <span class="hlt">transport</span> was again assessed. Hypoxia had no effect on Fe <span class="hlt">transport</span> across gut or skin, likely owing to the relative lack of change in haematological variables, and thus an unaltered Fe demand under such conditions. These data are the first to kinetically characterise the absorption of a nutritive trace metal across the epithelia of hagfish and add to the growing understanding of the role of the skin in nutritive <span class="hlt">transport</span> in this group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25462742','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25462742"><span id="translatedtitle">Reduced <span class="hlt">transport</span> potential of a palladium-doped zero valent <span class="hlt">iron</span> nanoparticle in a water saturated loamy sand.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Basnet, Mohan; Di Tommaso, Caroline; Ghoshal, Subhasis; Tufenkji, Nathalie</p> <p>2015-01-01</p> <p>Direct in situ injection of palladium-doped nanosized zero valent <span class="hlt">iron</span> (Pd-NZVI) particles can contribute to remediation of various environmental contaminants. A major challenge encountered is rapid aggregation of Pd-NZVI and hence very limited mobility. To reduce aggregation and concurrently improve particle mobility, the surface of bare Pd-NZVI can be modified with stabilizing surface modifiers. Selected surface-modified Pd-NZVI has shown dramatically improved stability and <span class="hlt">transport</span>. However, little is known regarding the effects of aquifer grain geochemical heterogeneity on the <span class="hlt">transport</span> and deposition behavior of surface-modified Pd-NZVI. Herein, the mobility of surface stabilized Pd-NZVI in two granular matrices representative of model ground water environments (quartz sand and loamy sand) was assessed over a wide range of environmentally relevant ionic strengths (IS). Carboxymethyl cellulose (CMC), soybean flour and rhamnolipid biosurfactant were used as Pd-NZVI surface modifiers. Our results show that, both in quartz sand and loamy sand, an increase in solution IS results in reduced Pd-NZVI <span class="hlt">transport</span>. Moreover, at a given water chemistry, Pd-NZVI <span class="hlt">transport</span> is notably attenuated in loamy sand implying that geochemical heterogeneity associated with loamy sand is a key factor influencing Pd-NZVI <span class="hlt">transport</span> potential. Experiments conducted at a higher Pd-NZVI particle concentration, to be more representative of field conditions, show that rhamnolipid and CMC are effective stabilizing agents even when 1 g/L Pd-NZVI is injected into quartz sand. Overall, this study emphasizes the extent to which variation in groundwater chemistry, coupled with changes in aquifer geochemistry, could dramatically alter the <span class="hlt">transport</span> potential of Pd-NZVI in the subsurface environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780022052','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780022052"><span id="translatedtitle">A study of characteristics of intercity <span class="hlt">transportation</span> <span class="hlt">systems</span>. Phase 1: Definition of <span class="hlt">transportation</span> comparison methodology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>English, J. M.; Smith, J. L.; Lifson, M. W.</p> <p>1978-01-01</p> <p>Decision making in early <span class="hlt">transportation</span> planning must be responsive to complex value <span class="hlt">systems</span> representing various policies and objectives. The assessment of alternative <span class="hlt">transportation</span> concepts during the early initial phases of the <span class="hlt">system</span> life cycle, when supportive research and technology development activities are defined, requires estimates of <span class="hlt">transportation</span>, environmental, and socio-economic impacts throughout the <span class="hlt">system</span> life cycle, which is a period of some 40 or 50 years. A unified methodological framework for comparing intercity passenger and freight <span class="hlt">transportation</span> <span class="hlt">systems</span> is described and is extended to include the comparison of long term <span class="hlt">transportation</span> trends arising from implementation of the various R & D programs. The attributes of existing and future <span class="hlt">transportation</span> <span class="hlt">systems</span> are reviewed in order to establish measures for comparison, define value functions, and attribute weightings needed for comparing alternative policy actions for furthering <span class="hlt">transportation</span> goals. Comparison criteria definitions and an illustrative example are included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5040547','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5040547"><span id="translatedtitle">Convective heat <span class="hlt">transport</span> in geothermal <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lippmann, M.J.; Bodvarsson, G.S.</p> <p>1986-08-01</p> <p>Most geothermal <span class="hlt">systems</span> under exploitation for direct use or electrical power production are of the hydrothermal type, where heat is transferred essentially by convection in the reservoir, conduction being secondary. In geothermal <span class="hlt">systems</span>, buoyancy effects are generally important, but often the fluid and heat flow patterns are largely controlled by geologic features (e.g., faults, fractures, continuity of layers) and location of recharge and discharge zones. During exploitation, these flow patterns can drastically change in response to pressure and temperature declines, and changes in recharge/discharge patterns. Convective circulation models of several geothermal <span class="hlt">systems</span>, before and after start of fluid production, are described, with emphasis on different characteristics of the <span class="hlt">systems</span> and the effects of exploitation on their evolution. Convective heat <span class="hlt">transport</span> in geothermal fields is discussed, taking into consideration (1) major geologic features; (2) temperature-dependent rock and fluid properties; (3) fracture- versus porous-medium characteristics; (4) single- versus two-phase reservoir <span class="hlt">systems</span>; and (5) the presence of noncondensible gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10139739','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10139739"><span id="translatedtitle">Road <span class="hlt">Transportable</span> Analytical Laboratory <span class="hlt">system</span>. Phase 1</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Finger, S.M.; Keith, V.F.; Spertzel, R.O.; De Avila, J.C.; O`Donnell, M.; Vann, R.L.</p> <p>1993-09-01</p> <p>This developmental effort clearly shows that a Road <span class="hlt">Transportable</span> Analytical Laboratory <span class="hlt">System</span> is a worthwhile and achievable goal. The RTAL is designed to fully analyze (radioanalytes, and organic and inorganic chemical analytes) 20 samples per day at the highest levels of quality assurance and quality control. It dramatically reduces the turnaround time for environmental sample analysis from 45 days (at a central commercial laboratory) to 1 day. At the same time each RTAL <span class="hlt">system</span> will save the DOE over $12 million per year in sample analysis costs compared to the costs at a central commercial laboratory. If RTAL <span class="hlt">systems</span> were used at the eight largest DOE facilities (at Hanford, Savannah River, Fernald, Oak Ridge, Idaho, Rocky Flats, Los Alamos, and the Nevada Test Site), the annual savings would be $96,589,000. The DOE`s internal study of sample analysis needs projects 130,000 environmental samples requiring analysis in FY 1994, clearly supporting the need for the RTAL <span class="hlt">system</span>. The cost and time savings achievable with the RTAL <span class="hlt">system</span> will accelerate and improve the efficiency of cleanup and remediation operations throughout the DOE complex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993larc.work...55S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993larc.work...55S"><span id="translatedtitle">Future space <span class="hlt">transportation</span> <span class="hlt">system</span> architecture avionics requirements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stone, Howard; Engelund, Walt</p> <p>1993-12-01</p> <p>NASA began a multi-center study in January 1993 to examine options for providing the most cost effective space <span class="hlt">transportation</span> <span class="hlt">system</span> in the future. The key advanced avionics requirements for these vehicle concepts are envisioned to provide significantly improved operational efficiency and effectiveness. It is very desirable to have adaptive guidance, navigation, and control approaches that will allow launch and return in almost any weather condition. The vehicles must be able to accommodate atmospheric density variations and winds without software changes. The flight operations must become much more autonomous in all flight regimes like an aircraft, and preflight checkout should make use of the onboard <span class="hlt">systems</span>. When the vehicle returns to the launch site, subsystem health must be known and maintenance tasks scheduled accordingly. Ground testing of most subsystems must be eliminated. Also, the health monitoring <span class="hlt">system</span> must be designed to enhance the ability to abort the mission significantly and save the crew and the vehicle. The displays and controls must be much less complex than current <span class="hlt">systems</span> and must significantly reduce pilot work load. It is important to have low power, light weight displays and controls. Rendezvous and docking and all flight phases must have autopilot capability to reduce pilot work load for routine operations and in abort situations. The vehicles must have the demonstrated ability to return to the launch site. Abort from all mission phases can put additional demands on the communications <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8083048','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8083048"><span id="translatedtitle">Benchmark test of neutron <span class="hlt">transport</span> calculations: indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by <span class="hlt">iron</span> simulating the Hiroshima atomic bomb casing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Iwatani, K; Hoshi, M; Shizuma, K; Hiraoka, M; Hayakawa, N; Oka, T; Hasai, H</p> <p>1994-10-01</p> <p>A benchmark test of the Monte Carlo neutron and photon <span class="hlt">transport</span> code <span class="hlt">system</span> (MCNP) was performed using a bare- and energy-moderated 252Cf fission neutron source which was obtained by transmission through 10-cm-thick <span class="hlt">iron</span>. An <span class="hlt">iron</span> plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate 152Eu and 60Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated 252Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen. PMID:8083048</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/54456','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/54456"><span id="translatedtitle">Benchmark test of neutron <span class="hlt">transport</span> calculations: Indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by <span class="hlt">iron</span> simulating the Hiroshima atomic bomb casing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Iwatani, Kazuo; Shizuma, Kiyoshi; Hasai, Hiromi; Hoshi, Masaharu; Hiraoka, Masayuki; Hayakawa, Norihiko; Oka, Takamitsu</p> <p>1994-10-01</p> <p>A benchmark test of the Monte Carlo neutron and photon <span class="hlt">transport</span> code <span class="hlt">system</span> (MCNP) was performed using a bare- and energy-moderated {sup 252}Cf fission neutron source which was obtained by transmission through 10-cm-thick <span class="hlt">iron</span>. An <span class="hlt">iron</span> plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate {sup 152}Eu and {sup 60}Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated {sup 252}Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen. 18 refs., 10 figs., 4 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8083048','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8083048"><span id="translatedtitle">Benchmark test of neutron <span class="hlt">transport</span> calculations: indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by <span class="hlt">iron</span> simulating the Hiroshima atomic bomb casing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Iwatani, K; Hoshi, M; Shizuma, K; Hiraoka, M; Hayakawa, N; Oka, T; Hasai, H</p> <p>1994-10-01</p> <p>A benchmark test of the Monte Carlo neutron and photon <span class="hlt">transport</span> code <span class="hlt">system</span> (MCNP) was performed using a bare- and energy-moderated 252Cf fission neutron source which was obtained by transmission through 10-cm-thick <span class="hlt">iron</span>. An <span class="hlt">iron</span> plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate 152Eu and 60Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated 252Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4356598','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4356598"><span id="translatedtitle">Microbial <span class="hlt">Iron</span> Mats at the Mid-Atlantic Ridge and Evidence that Zetaproteobacteria May Be Restricted to <span class="hlt">Iron</span>-Oxidizing Marine <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Scott, Jarrod J.; Breier, John A.; Luther, George W.; Emerson, David</p> <p>2015-01-01</p> <p>Chemolithoautotrophic <span class="hlt">iron</span>-oxidizing bacteria play an essential role in the global <span class="hlt">iron</span> cycle. Thus far, the majority of marine <span class="hlt">iron</span>-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine <span class="hlt">iron</span>-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of <span class="hlt">iron</span>-oxidizing communities at hydrothermal <span class="hlt">systems</span> along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent <span class="hlt">systems</span> on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit) using the ROV Jason II. The goal of these efforts was to determine if <span class="hlt">iron</span>-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high <span class="hlt">iron</span>(II) concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial <span class="hlt">iron</span> mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of <span class="hlt">iron</span>-oxyhydroxide structures, indicating that active <span class="hlt">iron</span>-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these <span class="hlt">iron</span> mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other <span class="hlt">iron</span>-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an <span class="hlt">iron</span> source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests that this organism</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25760332','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25760332"><span id="translatedtitle">Microbial <span class="hlt">iron</span> mats at the Mid-Atlantic Ridge and evidence that Zetaproteobacteria may be restricted to <span class="hlt">iron</span>-oxidizing marine <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Scott, Jarrod J; Breier, John A; Luther, George W; Emerson, David</p> <p>2015-01-01</p> <p>Chemolithoautotrophic <span class="hlt">iron</span>-oxidizing bacteria play an essential role in the global <span class="hlt">iron</span> cycle. Thus far, the majority of marine <span class="hlt">iron</span>-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine <span class="hlt">iron</span>-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of <span class="hlt">iron</span>-oxidizing communities at hydrothermal <span class="hlt">systems</span> along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent <span class="hlt">systems</span> on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit) using the ROV Jason II. The goal of these efforts was to determine if <span class="hlt">iron</span>-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high <span class="hlt">iron</span>(II) concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial <span class="hlt">iron</span> mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of <span class="hlt">iron</span>-oxyhydroxide structures, indicating that active <span class="hlt">iron</span>-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these <span class="hlt">iron</span> mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other <span class="hlt">iron</span>-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an <span class="hlt">iron</span> source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests that this organism</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25760332','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25760332"><span id="translatedtitle">Microbial <span class="hlt">iron</span> mats at the Mid-Atlantic Ridge and evidence that Zetaproteobacteria may be restricted to <span class="hlt">iron</span>-oxidizing marine <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Scott, Jarrod J; Breier, John A; Luther, George W; Emerson, David</p> <p>2015-01-01</p> <p>Chemolithoautotrophic <span class="hlt">iron</span>-oxidizing bacteria play an essential role in the global <span class="hlt">iron</span> cycle. Thus far, the majority of marine <span class="hlt">iron</span>-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine <span class="hlt">iron</span>-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of <span class="hlt">iron</span>-oxidizing communities at hydrothermal <span class="hlt">systems</span> along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from ru