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Sample records for haematology oxygen transport

  1. Artificial oxygen transport protein

    SciTech Connect

    Dutton, P. Leslie

    2014-09-30

    This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

  2. Atomic transport of oxygen

    SciTech Connect

    Routbort, J.L.; Tomlins, G.W.

    1994-06-15

    Atomic transport of oxygen in nonstoichiometric oxides is an extremely important topic which overlaps science and technology. In many cases the diffusion of oxygen controls sintering, grain growth, and creep. High oxygen diffusivity is critical for efficient operation of many fuel cells. Additionally, oxygen diffusivities are an essential ingredient in any point defect model. Secondary Ion Mass Spectrometry (SIMS) is the most accurate modern technique to measure oxygen tracer diffusion. This paper briefly reviews the principles and applications of SIMS for the measurement of oxygen transport. Case studies are taken from recent work on ZnO and some high-temperature superconductors.

  3. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, the possibility of using a more complex interfacial engineering approach to the development of reliable and stable oxygen transport perovskite ceramic membranes/metal seals is discussed. Experiments are presented and ceramic/metal interactions are characterized. Crack growth and fracture toughness of the membrane in the reducing conditions are also discussed. Future work regarding this approach is proposed are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  4. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  5. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-04-01

    This report covers the following tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints; Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability; Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres; Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures; Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability; and Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  6. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The CO-CO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  7. Oxygen Transport Membranes

    SciTech Connect

    S. Bandopadhyay

    2008-08-30

    The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

  8. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-12-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  9. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-05-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, in situ neutron diffraction was used to characterize the chemical and structural properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} (here after as L2SF55T) specimen, which was subject to measurements of neutron diffraction from room temperature to 900 C. It was found that space group of R3c yielded a better refinement than a cubic structure of Pm3m. Oxygen occupancy was nearly 3 in the region from room temperature to 700 C, above which the occupancy decreased due to oxygen loss. Dense OTM bars provided by Praxair were loaded to fracture at varying stress rates. Studies were done at room temperature in air and at 1000 C in a specified environment to evaluate slow crack growth behavior. The X-Ray data and fracture mechanisms points to non-equilibrium decomposition of the LSFCO OTM membrane. The non-equilibrium conditions could probably be due to the nature of the applied stress field (stressing rates) and leads to transition in crystal structures and increased kinetics of decomposition. The formations of a Brownmillerite or Sr2Fe2O5 type structures, which are orthorhombic are attributed to the ordering of oxygen vacancies. The cubic to orthorhombic transitions leads to 2.6% increase in strains and thus residual stresses generated could influence the fracture behavior of the OTM membrane. Continued investigations on the thermodynamic properties (stability and phase-separation behavior) and total conductivity of prototype membrane materials were carried out. The data are needed together with the kinetic information to develop a complete model for the membrane transport. Previously characterization, stoichiometry and conductivity measurements for samples of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} were reported. In this report

  10. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-10-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, Moessbauer spectroscopy was used to study the local environmentals of LSFT with various level of oxygen deficiency. Ionic valence state, magnetic interaction and influence of Ti on superexchange are discussed Stable crack growth studies on Dense OTM bars provided by Praxair were done at elevated temperature, pressure and elevated conditions. Post-fracture X-ray data of the OTM fractured at 1000 C in environment were refined by FullProf code and results indicate a distortion of the parent cubic perovskite to orthorhombic structure with reduced symmetry. TGA-DTA studies on the post-fracture samples also indicated residual effect arising from the thermal and stress history of the samples. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. The initial measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} are reported. Neutron diffraction measurements of the same composition are in agreement with both the stoichiometry and the kinetic behavior observed in coulometric titration measurements. A series of isotope transients under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The COCO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  11. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana

    2003-08-07

    In the present quarter, experiments are presented on ceramic/metal interactions of Zirconia/ Ni-B-Si system and with a thin Ti coating deposited on zirconia surface. Existing facilities were modified for evaluation of environmental assisted slow crack growth and creep in flexural mode. Processing of perovskites of LSC, LSF and LSCF composition were continued for evaluation of mechanical properties as a function of environment. These studies in parallel to those on the LSFCO composition is expect to yield important information on questions such as the role of cation segregation and the stability of the perovskite structure on crack initiation vs. crack growth. Studies have been continued on the La{sub 1-x}Sr{sub x}FeO{sub 3-d} composition using neutron diffraction and TGA studies. A transition from p-type to n-type of conductor was observed at relative low pO{sub 2}, at which the majority carriers changed from the holes to electrons because of the valence state decreases in Fe due to the further loss of oxygen. Investigation on the thermodynamic properties of the membrane materials are continued to develop a complete model for the membrane transport. Data obtained at 850 C show that the stoichiometry in La{sub 0.2}Sr{sub 0.8}Fe{sub 0.8}Cr{sub 0.2}O{sub 3-x} vary from {approx}2.85 to 2.6 over the pressure range studied. From the stoichiometry a lower limit of 2.6 corresponding to the reduction of all Fe{sup 4+} to Fe{sup 3+} and no reduction of Cr{sup 3+} is expected.

  12. Oxygen consumption and haematology of juvenile shortnose sturgeon Acipenser brevirostrum during an acute 24 h saltwater challenge.

    PubMed

    Penny, F M; Kieffer, J D

    2014-04-01

    This study focused on the acute physiological responses to saltwater exposure in juvenile shortnose sturgeon Acipenser brevirostrum. In two separate laboratory experiments, 2 year-old A. brevirostrum were exposed to either full (32) or half-strength (16) seawater for up to 24 h. First, oxygen consumption rates were used to estimate the metabolic costs over 24 h. Secondly, blood and muscle samples were analysed at 6, 12 and 24 h for water loss, various measures of osmoregulatory status (plasma osmolality and ions) and other standard haematological variables. Juveniles exposed to full-strength seawater showed significant decreases in oxygen consumption rates during the 24 h exposure. Furthermore, seawater-exposed fish had significantly increased plasma osmolality, ions (Na(+) and Cl(-)) and a 17% decrease in total wet mass over the 24 h exposure period. To a lesser extent, increases in osmolality, ions and mass loss were observed in fish exposed to half-strength seawater but no changes to oxygen consumption. Cortisol was also significantly increased in fish exposed to full-strength seawater. While plasma protein was elevated following 24 h in full-strength seawater, haemoglobin, haematocrit and plasma glucose levels did not change with increased salinity. These results imply an inability of juvenile A. brevirostrum to regulate water and ions in full-strength seawater within 24 h. Nonetheless, no mortality occurred in any exposure, suggesting that juvenile A. brevirostrum can tolerate short periods in saline environments. PMID:24628001

  13. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-05-01

    the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The CO-CO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  14. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-08-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Modeling of the isotopic transients on operating membranes (LSCrF-2828 at 900 C) and a ''frozen'' isotope profile have been analyzed in conjunction with a 1-D model to reveal the gradient in oxygen diffusivity through the membrane under conditions of high chemical gradients.

  15. Haematological rather than skeletal muscle adaptations contribute to the increase in peak oxygen uptake induced by moderate endurance training.

    PubMed

    Montero, David; Cathomen, Adrian; Jacobs, Robert A; Flück, Daniela; de Leur, Jeroen; Keiser, Stefanie; Bonne, Thomas; Kirk, Niels; Lundby, Anne-Kristine; Lundby, Carsten

    2015-10-15

    It remains unclear whether improvements in peak oxygen uptake (V̇(O2peak)) following endurance training (ET) are primarily determined by central and/or peripheral adaptations. Herein, we tested the hypothesis that the improvement in V̇(O2peak) following 6 weeks of ET is mainly determined by haematological rather than skeletal muscle adaptations. Sixteen untrained healthy male volunteers (age = 25 ± 4 years, V̇(O2peak) = 3.5 ± 0.5 l min(-1)) underwent supervised ET (6 weeks, 3-4 sessions per week). V̇(O2peak), peak cardiac output (Q̇(peak)), haemoglobin mass (Hb(mass)) and blood volumes were assessed prior to and following ET. Skeletal muscle biopsies were analysed for mitochondrial volume density (Mito(VD)), capillarity, fibre types and respiratory capacity (OXPHOS). After the post-ET assessment, red blood cell volume (RBCV) was re-established at the pre-ET level by phlebotomy and V̇(O2peak) and Q̇(peak) were measured again. We speculated that the contribution of skeletal muscle adaptations to the ET-induced increase in V̇(O2peak) would be revealed when controlling for haematological adaptations. V̇(O2peak) and Q̇(peak) were increased (P < 0.05) following ET (9 ± 8 and 7 ± 6%, respectively) and decreased (P < 0.05) after phlebotomy (-7 ± 7 and -10 ± 7%). RBCV, plasma volume and Hb(mass) all increased (P < 0.05) after ET (8 ± 4, 4 ± 6 and 6 ± 5%). As for skeletal muscle adaptations, capillary-to-fibre ratio and total Mito(VD) increased (P < 0.05) following ET (18 ± 16 and 43 ± 30%), but OXPHOS remained unaltered. Through stepwise multiple regression analysis, Q̇(peak), RBCV and Hb(mass) were found to be independent predictors of V̇(O2peak). In conclusion, the improvement in V̇(O2peak) following 6 weeks of ET is primarily attributed to increases in Q̇(peak) and oxygen-carrying capacity of blood in untrained healthy young subjects. PMID:26282186

  16. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham

    2006-12-31

    Ti doping on La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} (LSF) tends to increase the oxygen equilibration kinetics of LSF in lower oxygen activity environment because of the high valence state of Ti. However, the addition of Ti decreases the total conductivity because the acceptor ([Sr{prime}{sub La}]) is compensated by the donor ([Ti{sub Fe}{sup {sm_bullet}}]) which decreases the carrier concentration. The properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 1-x}Ti{sub x}O{sub 3-{delta}} (LSFT, x = 0.45) have been experimentally and theoretically investigated to elucidate (1) the dependence of oxygen occupancy and electrochemical properties on temperature and oxygen activity by thermogravimetric analysis (TGA) and (2) the electrical conductivity and carrier concentration by Seebeck coefficient and electrical measurements. In the present study, dual phase (La{sub 0.2}Sr{sub 0.8}Fe{sub 0.6}Ti{sub 0.4}O{sub 3-{delta}}/Ce{sub 0.9}Gd{sub 0.1}O{sub 2-{delta}}) membranes have been evaluated for structural properties such as hardness, fracture toughness and flexural strength. The effect of high temperature and slightly reducing atmosphere on the structural properties of the membranes was studied. The flexural strength of the membrane decreases upon exposure to slightly reducing conditions at 1000 C. The as-received and post-fractured membranes were characterized using XRD, SEM and TG-DTA to understand the fracture mechanisms. Changes in structural properties of the composite were sought to be correlated with the physiochemical features of the two-phases. We have reviewed the electrical conductivity data and stoichiometry data for La{sub 0.2}Sr{sub 0.8}Cr{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} some of which was reported previously. Electrical conductivity data for La{sub 0.2}Sr{sub 0.8}Cr{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCrF) were obtained in the temperature range, 752 {approx} 1055 C and in the pO{sub 2} range, 10{sup -18} {approx} 0.5 atm. The slope of the plot of log {sigma} vs

  17. Composite oxygen transport membrane

    SciTech Connect

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2014-08-05

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  18. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-01-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals.

  19. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; W.B. Yelon; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and initial studies on newer composition of Ti doped LSF. Dense OTM bars provided by Praxair were loaded to fracture at varying stress rates. Studies were done at room temperature in air and at 1000 C in a specified environment to evaluate slow crack growth behavior. In addition, studies were also begun to obtain reliable estimates of fracture toughness and stable crack growth in specific environments. Newer composition of Ti doped LSF membranes were characterized by neutron diffraction analysis. Quench studies indicated an apparent correlation between the unit cell volume and oxygen occupancy. The studies however, indicated an anomaly of increasing Fe/Ti ratio with change in heat treatment. Ti doped LSF was also characterized for stoichiometry as a function of temp and pO{sub 2}. The non stoichiometry parameter {delta} was observed to increase almost linearly on lowering pO{sub 2} until a ideal stoichiometric composition of {delta} = 0.175 was approached.

  20. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, experiments are presented on ceramic/metal interactions of Zirconia/Ni-B-Si system and with a thin Ti coating deposited on zirconia surface. Processing of perovskites of LSC, LSF and LSCF composition for evaluation of mechanical properties as a function of environment are begun. The studies are to be in parallel with LSFCO composition to characterize the segregation of cations and slow crack growth in environmental conditions. La{sub 1-x}Sr{sub x}FeO{sub 3-d} has also been characterized for paramagnetic ordering at room temperature and the evolution of magnetic moments as a function of temperature are investigated. Investigation on the thermodynamic properties of the membrane materials are continued to develop a complete model for the membrane transport.

  1. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-11-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the current research, the electrical conductivity and Seebeck coefficient were measured as a function of temperature in air. Based on these measurements, the charge carrier concentration, net acceptor dopant concentration, activation energy of conduction and mobility were estimated. The studies on the fracture toughness of the LSFT and dual phase membranes at room temperature have been completed and reported previously. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affects the mechanical properties. To study the effect of temperature on the membranes when exposed to an inert environment, the membranes (LAFT and Dual phase) were heat treated at 1000 C in air and N{sub 2} atmosphere and hardness and fracture toughness of the membranes were studied after the treatment. The indentation method was used to find the fracture toughness and the effect of the heat treatment on the mechanical properties of the membranes. Further results on the investigation of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appears to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model will serve to study ''frozen'' profiles in patterned or composite membranes.

  2. Composite oxygen ion transport element

    DOEpatents

    Chen, Jack C.; Besecker, Charles J.; Chen, Hancun; Robinson, Earil T.

    2007-06-12

    A composite oxygen ion transport element that has a layered structure formed by a dense layer to transport oxygen ions and electrons and a porous support layer to provide mechanical support. The dense layer can be formed of a mixture of a mixed conductor, an ionic conductor, and a metal. The porous support layer can be fabricated from an oxide dispersion strengthened metal, a metal-reinforced intermetallic alloy, a boron-doped Mo.sub.5Si.sub.3-based intermetallic alloy or combinations thereof. The support layer can be provided with a network of non-interconnected pores and each of said pores communicates between opposite surfaces of said support layer. Such a support layer can be advantageously employed to reduce diffusion resistance in any type of element, including those using a different material makeup than that outlined above.

  3. Catalyst containing oxygen transport membrane

    DOEpatents

    Christie, Gervase Maxwell; Wilson, Jamie Robyn; van Hassel, Bart Antonie

    2012-12-04

    A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a high average pore diameter and the intermediate porous layer has a lower permeability and lower pore diameter than the porous support layer. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

  4. Oxygen transport and exchange in oxide ceramics

    NASA Astrophysics Data System (ADS)

    Steele, B. C. H.

    1994-04-01

    Oxygen transport in most oxide ceramics incorporated in solid oxide fuel cells (SOFC) involves the movement of oxygen ion vacancies. It is the relative magnitude of oxygen ion vacancy and electronic charge carrier concentrations and mobilities which determines whether oxide materials can function as effective electrolyte or electrode components. Examination of relevant data suggests that zirconia- and ceria-based electrolytes are unlikely to be replaced in SOFC systems operating in the temperature range 450-950 C. Oxygen ion vacancies are also involved in the cathodic reduction of oxygen and influence the magnitude of the associated exchange current density which can be measured by isotopic oxygen exchange measurements. Oxygen vacancy concentrations are also implicated in thermal expansion coefficient values and chemical stability considerations. It follows that optimisation of the cathode composition requires many conflicting requirements to be satisfied. However for operation at 800 C, electrolyte, electrode and bipolar plate materials are available to ensure power densities approaching 0.5 W sq cm. In contrast, direct methanol SOFC systems operating at 500 C necessitate the development of alternative electrode materials. The successful exploitation of our knowledge about oxygen ion vacancy transport in ceramic oxides has now stimulated research into the role of protons in oxide lattices, and it is postulated that protonic/hydroxyl ion transport could be important in the development of alternative anode components.

  5. Cardiac remodelling, blood chemistry, haematology and oxygen consumption of Atlantic cod, Gadus morhua L., induced by experimental haemolytic anaemia with phenylhydrazine.

    PubMed

    Powell, Mark D; Burke, Melissa S; Dahle, Dalia

    2011-03-01

    Anaemia is a common pathology associated with many infectious and non-infectious diseases. The effects of haemolytic anaemia induced by i.p. injection of phenylhydrazine (PHZ) were studied in Atlantic cod. Phenylhydrazine injection (0.3 mg kg(-1)) in a DMSO and saline vehicle induced a reproducible and stable anaemia reducing haematocrit, (Hct) by 62% over 3 weeks. Controls consisted of fish injected with saline and DMSO/saline vehicle with minimal effects on Hct or whole blood haemoglobin (Hb). Although anaemia resulted in reduced blood lactate and glucose in PHZ injected fish, there were no effects of anaemia on blood, sodium, chloride or potassium. Similarly, there were no changes in the relative proportions of leucocytes in the blood although an increase in the number of immature erythrocytes was observed in the anaemic fish. Anaemic fish showed a 29 and 22% increase in cardiac somatic index (CSI) relative to saline and vehicle controls, respectively, although there were no significant differences in the linear dimensions of the ventricle. Changes in cardiac somatic and ventricular somatic index correlated positively and significantly with Hct but not with whole blood Hb concentration. Anaemic fish had significantly reduced resting routine oxygen consumption compared with vehicle controls but were not able to increase oxygen consumption following a bout of exhaustive exercise. Plasma lactate concentrations increased significantly after exercise to a greater extent in anaemic fish compared with vehicle control fish. Phenylhydrazine is a useful model for studying haemolytic anaemia in Atlantic cod with minimal effects on blood biochemistry and haematology and clearly reduces the aerobic capacity in Atlantic cod. PMID:20585853

  6. Modeling Oxygen Transport in the Human Placenta

    NASA Astrophysics Data System (ADS)

    Serov, Alexander; Filoche, Marcel; Salafia, Carolyn; Grebenkov, Denis

    Efficient functioning of the human placenta is crucial for the favorable pregnancy outcome. We construct a 3D model of oxygen transport in the placenta based on its histological cross-sections. The model accounts for both diffusion and convention of oxygen in the intervillous space and allows one to estimate oxygen uptake of a placentone. We demonstrate the existence of an optimal villi density maximizing the uptake and explain it as a trade-off between the incoming oxygen flow and the absorbing villous surface. Calculations performed for arbitrary shapes of fetal villi show that only two geometrical characteristics - villi density and the effective villi radius - are required to predict fetal oxygen uptake. Two combinations of physiological parameters that determine oxygen uptake are also identified: maximal oxygen inflow of a placentone and the Damköhler number. An automatic image analysis method is developed and applied to 22 healthy placental cross-sections demonstrating that villi density of a healthy human placenta lies within 10% of the optimal value, while overall geometry efficiency is rather low (around 30-40%). In a perspective, the model can constitute the base of a reliable tool of post partum oxygen exchange efficiency assessment in the human placenta. Also affiliated with Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA.

  7. Safety Standard for Oxygen and Oxygen Systems: Guidelines for Oxygen System Design, Materials Selection, Operations, Storage, and Transportation

    NASA Technical Reports Server (NTRS)

    1996-01-01

    NASA's standard for oxygen system design, materials selection, operation, and transportation is presented. Minimum guidelines applicable to NASA Headquarters and all NASA Field Installations are contained.

  8. Case-Based Learning of Blood Oxygen Transport

    ERIC Educational Resources Information Center

    Cliff, William H.

    2006-01-01

    A case study about carbon monoxide poisoning was used help students gain a greater understanding of the physiology of oxygen transport by the blood. A review of student answers to the case questions showed that students can use the oxygen-hemoglobin dissociation curve to make meaningful determinations of oxygen uptake and delivery. However, the…

  9. Radionuclides in haematology

    SciTech Connect

    Lewis, S.M.; Bayly, R.J.

    1986-01-01

    This book contains the following chapters: Some prerequisites to the use of radionuclides in haematology; Instrumentation and counting techniques; In vitro techniques; Cell labelling; Protein labelling; Autoradiography; Imaging and quantitative scanning; Whole body counting; Absorption and excretion studies; Blood volume studies; Plasma clearance studies; and Radionuclide blood cell survival studies.

  10. Mathematical Model of Oxygen Transport in Tuberculosis Granulomas

    PubMed Central

    Datta, Meenal; Via, Laura E.; Chen, Wei; Baish, James W.; Xu, Lei; Barry, Clifton E.; Jain, Rakesh K.

    2016-01-01

    Pulmonary granulomas—the hallmark of Mycobacterium tuberculosis (MTB) infection—are dense cellular lesions that often feature regions of hypoxia and necrosis, partially due to limited transport of oxygen. Low oxygen in granulomas can impair the host immune response, while MTB are able to adapt and persist in hypoxic environments. Here, we used a physiologically based mathematical model of oxygen diffusion and consumption to calculate oxygen profiles within the granuloma, assuming Michaelis–Menten kinetics. An approximate analytical solution—using a priori and newly estimated parameters from experimental data in a rabbit model of tuberculosis—was able to predict the size of hypoxic and necrotic regions in agreement with experimental results from the animal model. Such quantitative understanding of transport limitations can inform future tuberculosis therapeutic strategies that may include adjunct host-directed therapies that facilitate oxygen and drug delivery for more effective treatment. PMID:26253038

  11. Mathematical Model of Oxygen Transport in Tuberculosis Granulomas.

    PubMed

    Datta, Meenal; Via, Laura E; Chen, Wei; Baish, James W; Xu, Lei; Barry, Clifton E; Jain, Rakesh K

    2016-04-01

    Pulmonary granulomas-the hallmark of Mycobacterium tuberculosis (MTB) infection-are dense cellular lesions that often feature regions of hypoxia and necrosis, partially due to limited transport of oxygen. Low oxygen in granulomas can impair the host immune response, while MTB are able to adapt and persist in hypoxic environments. Here, we used a physiologically based mathematical model of oxygen diffusion and consumption to calculate oxygen profiles within the granuloma, assuming Michaelis-Menten kinetics. An approximate analytical solution-using a priori and newly estimated parameters from experimental data in a rabbit model of tuberculosis-was able to predict the size of hypoxic and necrotic regions in agreement with experimental results from the animal model. Such quantitative understanding of transport limitations can inform future tuberculosis therapeutic strategies that may include adjunct host-directed therapies that facilitate oxygen and drug delivery for more effective treatment. PMID:26253038

  12. Oxygen transport by oxygen potential gradient in dense ceramic oxide membranes

    SciTech Connect

    Maiya, P.S.; Balachandran, U.; Dusek, J.T.; Mieville, R.L.; Kleefisch, M.S.; Udovich, C.A.

    1996-05-01

    Numerous studies have been conducted in recent years on the partial oxidation of methane to synthesis gas (syngas: CO + H{sub 2}) with air as the oxidant. In partial oxidation, a mixed-oxide ceramic membrane selectively transports oxygen from the air; this transport is driven by the oxygen potential gradient. Of the several ceramic materials the authors have tested, a mixed oxide based on the Sr-Fe-Co-O system has been found to be very attractive. Extensive oxygen permeability data have been obtained for this material in methane conversion experiments carried out in a reactor. The data have been analyzed by a transport equation based on the phenomenological theory of diffusion under oxygen potential gradients. Thermodynamic calculations were used to estimate the driving force for the transport of oxygen ions. The results show that the transport equation deduced from the literature describes the permeability data reasonably well and can be used to determine the diffusion coefficients and the associated activation energy of oxygen ions in the ceramic membrane material.

  13. Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves

    NASA Astrophysics Data System (ADS)

    Lindbergh, Tobias; Larsson, Marcus; Szabó, Zoltán; Casimir-Ahn, Henrik; Strömberg, Tomas

    2010-03-01

    Intramyocardial oxygen transport was assessed during open-chest surgery in calves by diffuse reflectance spectroscopy using a small intramuscular fiber-optic probe. The sum of hemo- and myoglobin tissue fraction and oxygen saturation, the tissue fraction and oxidation of cytochrome aa3, and the tissue fraction of methemoglobin were estimated using a calibrated empirical light transport model. Increasing the oxygen content in the inhaled gas, 21%-50%-100%, in five calves (group A) gave an increasing oxygen saturation of 19+/-4%, 24+/-5%, and 28+/-8% (p<0.001, ANOVA repeated measures design) and mean tissue fractions of 1.6% (cytochrome aa3) and 1.1% (hemo- and myoglobin). Cardiac arrest in two calves gave an oxygen saturation lower than 5%. In two calves (group B), a left ventricular assistive device (LVAD pump) was implanted. Oxygen saturation in group B animals increased with LVAD pump speed (p<0.001, ANOVA) and with oxygen content in inhaled gas (p<0.001, ANOVA). The cytochrome aa3 oxidation level was above 96% in both group A and group B calves, including the two cases involving cardiac arrest. In conclusion, the estimated tissue fractions and oxygenation/oxidation levels of the myocardial chromophores during respiratory and hemodynamic provocations were in agreement with previously presented results, demonstrating the potential of the method.

  14. Oxygen radicals diminish dopamine transporter function in rat striatum.

    PubMed

    Fleckenstein, A E; Metzger, R R; Beyeler, M L; Gibb, J W; Hanson, G R

    1997-09-01

    Incubation of striatal synaptosomes with the oxygen radical generating enzyme, xanthine oxidase, decreased [3H]dopamine uptake: an effect attributable to a decreased Vmax. Concurrent incubation with the superoxide radical scavenger, superoxide dismutase, abolished the xanthine oxidase-induced decrease. These results indicate that, like methamphetamine administration in vivo, reactive oxygen species diminish dopamine transporter function in vitro. The significance of these findings to mechanisms responsible for effects of methamphetamine is discussed. PMID:9346337

  15. Oxygen Transport in Melts Based on V2O5

    NASA Astrophysics Data System (ADS)

    Klimashin, Anton; Belousov, Valery

    2016-02-01

    An oxygen ion transport model was developed for oxide melts based on V2O5. Within the framework of this model, the values of the parabolic rate constant of catastrophic oxidation of V2O5-deposited copper and the oxygen flux through the slags based on molten V2O5 were calculated and compared with experimental data. The calculated and experimental values are of the same order of magnitude which shows an adequacy of the model.

  16. Method measuring oxygen tension and transport within subcutaneous devices

    PubMed Central

    Weidling, John; Sameni, Sara; Lakey, Jonathan R. T.; Botvinick, Elliot

    2014-01-01

    Abstract. Cellular therapies hold promise to replace the implantation of whole organs in the treatment of disease. For most cell types, in vivo viability depends on oxygen delivery to avoid the toxic effects of hypoxia. A promising approach is the in situ vascularization of implantable devices which can mediate hypoxia and improve both the lifetime and utility of implanted cells and tissues. Although mathematical models and bulk measurements of oxygenation in surrounding tissue have been used to estimate oxygenation within devices, such estimates are insufficient in determining if supplied oxygen is sufficient for the entire thickness of the implanted cells and tissues. We have developed a technique in which oxygen-sensitive microparticles (OSMs) are incorporated into the volume of subcutaneously implantable devices. Oxygen partial pressure within these devices can be measured directly in vivo by an optical probe placed on the skin surface. As validation, OSMs have been incorporated into alginate beads, commonly used as immunoisolation devices to encapsulate pancreatic islet cells. Alginate beads were implanted into the subcutaneous space of Sprague–Dawley rats. Oxygen transport through beads was characterized from dynamic OSM signals in response to changes in inhaled oxygen. Changes in oxygen dynamics over days demonstrate the utility of our technology. PMID:25162910

  17. Oxygen transport as a structure probe for amorphous polymeric systems

    NASA Astrophysics Data System (ADS)

    Liu, Richard Yufeng

    Although permeability of small molecules is often measured as an important performance property, deeper analysis of the transport characteristics provides insight into polymer structure, especially if used in combination with other characterization techniques. Transport of small gas molecules "senses" the permeable amorphous structure and probes the nature of free volume. This work focuses on oxygen transport, supplemented with other methods of physical analysis, as a probe for: (1) the nature of free volume in the oriented glassy state, (2) the role of amorphous phase orientation and strain-induced crystallization on oxygen barrier properties of polyester blends, and (3) the nature of interphase between immiscible amorphous polymers in forced-assemblies. In the first part, the mechanism of oxygen transport in oriented glassy polyesters is examined. PET, PETBB55, and PEN were oriented by cold-drawing. Densification of the glassy state correlates with conformational transformation of glycol linkages from gauche to trans. Orientation is seen as a process of decreasing the amount of excess-hole free volume and bringing the nonequilibrium polymer glass closer to the equilibrium condition. Further insights into the free volume structure are obtained by exploring the relationships between free volume structure and oxygen transport property using a simple lattice-hole model. In the second part, oxygen transport through polyester blends is investigated. It is found that cold-drawing the blocky PET/PETBB55 produces highly oriented PETBB55 frustrated LCP microfibrils, which prevent relaxation of the continuous PET phase. On the other hand, careful examination of oxygen barrier for the PET/PEI blends leads to a two-phase model from which the amount of crystallinity and the amorphous phase density are determined. In the third part, oxygen permeability is utilized as a powerful probe for interphase thickness between immiscible polymers, which is as thin as a few nanometers. We

  18. Transportation of Critically Ill Patients on Extracorporeal Membrane Oxygenation

    PubMed Central

    Broman, L. Mikael; Frenckner, Björn

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) may be a life-saving procedure for patients with severe reversible pulmonary or cardiac failure or for patients in need for a bridge to transplantation. ECMO is provided by specialized centers, but patients in need of ECMO are frequently taken care of at other centers. Conventional transports to an ECMO center can be hazardous and deaths have been described. For this reason, many ECMO centers have developed transport programs with mobile ECMO. After request, the mobile team including all necessary equipment to initiate ECMO is sent to the referring hospital, where the patient is cannulated and ECMO commenced. The patient is then transported on ECMO to the ECMO facility by road, helicopter, or fixed-wing aircraft depending on distance, weather conditions, etc. Eight publications have reported series of more than 50 transports on ECMO of which the largest included over 700. Together, these papers report on more than 1400 patient transports on ECMO. Two deaths during transport have occurred. A number of other adverse events are described, but without effect on patient outcome. Survival of patients transported on ECMO is equivalent to that of non-transported ECMO patients. It is concluded that long-, short-distance interhospital transports on ECMO can be performed safely. The staff should be experienced and highly competent in intensive care, ECMO cannulation, ECMO treatment, intensive care transport, and air transport medicine. PMID:27379221

  19. Transportation of Critically Ill Patients on Extracorporeal Membrane Oxygenation.

    PubMed

    Broman, L Mikael; Frenckner, Björn

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) may be a life-saving procedure for patients with severe reversible pulmonary or cardiac failure or for patients in need for a bridge to transplantation. ECMO is provided by specialized centers, but patients in need of ECMO are frequently taken care of at other centers. Conventional transports to an ECMO center can be hazardous and deaths have been described. For this reason, many ECMO centers have developed transport programs with mobile ECMO. After request, the mobile team including all necessary equipment to initiate ECMO is sent to the referring hospital, where the patient is cannulated and ECMO commenced. The patient is then transported on ECMO to the ECMO facility by road, helicopter, or fixed-wing aircraft depending on distance, weather conditions, etc. Eight publications have reported series of more than 50 transports on ECMO of which the largest included over 700. Together, these papers report on more than 1400 patient transports on ECMO. Two deaths during transport have occurred. A number of other adverse events are described, but without effect on patient outcome. Survival of patients transported on ECMO is equivalent to that of non-transported ECMO patients. It is concluded that long-, short-distance interhospital transports on ECMO can be performed safely. The staff should be experienced and highly competent in intensive care, ECMO cannulation, ECMO treatment, intensive care transport, and air transport medicine. PMID:27379221

  20. Oxygen dynamics and transport in the Mediterranean sponge Aplysina aerophoba.

    PubMed

    Hoffmann, Friederike; Røy, Hans; Bayer, Kristina; Hentschel, Ute; Pfannkuchen, Martin; Brümmer, Franz; de Beer, Dirk

    2008-01-01

    The Mediterranean sponge Aplysina aerophoba kept in aquaria or cultivation tanks can stop pumping for several hours or even days. To investigate changes in the chemical microenvironments, we measured oxygen profiles over the surface and into the tissue of pumping and non-pumping A. aerophoba specimens with Clark-type oxygen microelectrodes (tip diameters 18-30 μm). Total oxygen consumption rates of whole sponges were measured in closed chambers. These rates were used to back-calculate the oxygen distribution in a finite-element model. Combining direct measurements with calculations of diffusive flux and modeling revealed that the tissue of non-pumping sponges turns anoxic within 15 min, with the exception of a 1 mm surface layer where oxygen intrudes due to molecular diffusion over the sponge surface. Molecular diffusion is the only transport mechanism for oxygen into non-pumping sponges, which allows total oxygen consumption rates of 6-12 μmol cm(-3) sponge day(-1). Sponges of different sizes had similar diffusional uptake rates, which is explained by their similar surface/volume ratios. In pumping sponges, oxygen consumption rates were between 22 and 37 μmol cm(-3) sponge day(-1), and the entire tissue was oxygenated. Combining different approaches of direct oxygen measurement in living sponges with a dynamic model, we can show that tissue anoxia is a direct function of the pumping behavior. The sponge-microbe system of A. aerophoba thus has the possibility to switch actively between aerobic and anaerobic metabolism by stopping the water flow for more than 15 min. These periods of anoxia will greatly influence physiological variety and activity of the sponge microbes. Detailed knowledge about the varying chemical microenvironments in sponges will help to develop protocols to cultivate sponge-associated microbial lineages and improve our understanding of the sponge-microbe-system. PMID:24391232

  1. Computation of the unsteady facilitated transport of oxygen in hemoglobin

    NASA Technical Reports Server (NTRS)

    Davis, Sanford

    1990-01-01

    The transport of a reacting permeant diffusing through a thin membrane is extended to more realistic dissociation models. A new nonlinear analysis of the reaction-diffusion equations, using implicit finite-difference methods and direct block solvers, is used to study the limits of linearized and equilibrium theories. Computed curves of molecular oxygen permeating through hemoglobin solution are used to illustrate higher-order reaction models, the effect of concentration boundary layers at the membrane interfaces, and the transient buildup of oxygen flux.

  2. Haematological abnormalities in mitochondrial disorders

    PubMed Central

    Finsterer, Josef; Frank, Marlies

    2015-01-01

    INTRODUCTION This study aimed to assess the kind of haematological abnormalities that are present in patients with mitochondrial disorders (MIDs) and the frequency of their occurrence. METHODS The blood cell counts of a cohort of patients with syndromic and non-syndromic MIDs were retrospectively reviewed. MIDs were classified as ‘definite’, ‘probable’ or ‘possible’ according to clinical presentation, instrumental findings, immunohistological findings on muscle biopsy, biochemical abnormalities of the respiratory chain and/or the results of genetic studies. Patients who had medical conditions other than MID that account for the haematological abnormalities were excluded. RESULTS A total of 46 patients (‘definite’ = 5; ‘probable’ = 9; ‘possible’ = 32) had haematological abnormalities attributable to MIDs. The most frequent haematological abnormality in patients with MIDs was anaemia. 27 patients had anaemia as their sole haematological problem. Anaemia was associated with thrombopenia (n = 4), thrombocytosis (n = 2), leucopenia (n = 2), and eosinophilia (n = 1). Anaemia was hypochromic and normocytic in 27 patients, hypochromic and microcytic in six patients, hyperchromic and macrocytic in two patients, and normochromic and microcytic in one patient. Among the 46 patients with a mitochondrial haematological abnormality, 78.3% had anaemia, 13.0% had thrombopenia, 8.7% had leucopenia and 8.7% had eosinophilia, alone or in combination with other haematological abnormalities. CONCLUSION MID should be considered if a patient’s abnormal blood cell counts (particularly those associated with anaemia, thrombopenia, leucopenia or eosinophilia) cannot be explained by established causes. Abnormal blood cell counts may be the sole manifestation of MID or a collateral feature of a multisystem problem. PMID:26243978

  3. Oxygen transport as a structure probe for heterogeneous polymeric systems

    NASA Astrophysics Data System (ADS)

    Hu, Yushan

    Although permeability of small molecules is often measured as an important performance property, deeper analysis of the transport characteristics provides insight into polymer structure, especially if used in combination with other characterization techniques. Transport of small gas molecules senses the permeable amorphous structure and probes the nature of free volume. This work focuses on oxygen transport, supplemented with other methods of physical analysis, as a probe for: (1) the nature of free volume and crystalline morphology in the crystallized glassy state, (2) the nature of free volume and hierarchical structure in liquid crystalline polymers, and (3) the role of dispersed polyamide phase geometry on oxygen barrier properties of poly(ethylene terephthalate) (PET)/polyamide blends. In the first part, the improvement in oxygen-barrier properties of glassy polyesters by crystallization was examined. Examples included poly(ethylene naphthalate) (PEN), and a copolymer based on PET in which 55 mol% terephthalate was replaced with 4,4'-bibenzoate. Explanation of the unexpectedly high solubility of crystallized PEN required a two-phase transport model consisting of an impermeable crystalline phase of constant density and a permeable amorphous phase of variable density. The resulting relationship between oxygen solubility and amorphous phase density was consistent with free volume concepts of gas sorption. In the second part, oxygen barrier properties of liquid crystalline (LC) polyesters based on poly(diethylene glycol 4,4'-bibenzoate) (PDEGBB) were studied. This study extended the 2-phase transport model for oxygen transport of non-LC crystalline polymers to a smectic LCP. It was possible to systematically vary the solid state structure of (PDEGBB) from LC glass to crystallized LC glass. The results were consistent with a liquid crystalline state intermediate between the permeable amorphous glass and the impermeable 3-dimensional crystal. In this interpretation

  4. Limits for oxygen and substrate transport in mammals.

    PubMed

    Hoppeler, H; Weibel, E R

    1998-04-01

    Environmental oxygen is transported by the respiratory cascade to the site of oxidation in active tissues. Under conditions of heavy exercise, it is ultimately the working skeletal muscle cells that set the aerobic demand because over 90 % of energy is spent in muscle cells. The pathways for oxygen and substrates converge in muscle mitochondria. In mammals, a structural limitation of carbohydrate and lipid transfer from the microvascular system to the muscle cells is reached at a moderate work intensity (i.e. at 40-50 % of VO2max). At higher work rates, intracellular substrate stores must be used for oxidation. Because of the importance of these intracellular stores for aerobic work, we find larger intramyocellular substrate stores in 'athletic' species as well as in endurance-trained human athletes. The transfer limitations for carbohydrates and lipids at the level of the sarcolemma imply that the design of the respiratory cascade from lungs to muscle mitochondria reflects primarily oxygen demand. Comparative studies indicate that the oxidative capacity of skeletal muscle tissue, and hence maximal oxygen demand, is adjusted by varying mitochondrial content. At the level of microcirculatory oxygen supply, it is found that muscle tissue capillarity is adjusted to muscle oxygen demand but that the capillary erythrocyte volume also plays a role. Oxygen delivery by the heart has long been recognized to be a key link in the oxygen transport chain. In allometric variation it is heart rate and in adaptive variation it is essentially stroke volume, and hence heart size, that determines maximal cardiac output. Again, haematocrit is an important variable that allows the heart of athletic species to generate higher flux rates for oxygen. The pulmonary gas exchanger offers only a negligible resistance to oxygen flux to the periphery. However, in contrast to all other steps in the respiratory cascade, the lungs have only a minimal phenotypical plasticity and appear, therefore

  5. Haematological manifestations of lupus

    PubMed Central

    Fayyaz, Anum; Igoe, Ann; Kurien, Biji T; Danda, Debashish; James, Judith A; Stafford, Haraldine A; Scofield, R Hal

    2015-01-01

    Our purpose was to compile information on the haematological manifestations of systemic lupus erythematosus (SLE), namely leucopenia, lymphopenia, thrombocytopenia, autoimmune haemolytic anaemia (AIHA), thrombotic thrombocytopenic purpura (TTP) and myelofibrosis. During our search of the English-language MEDLINE sources, we did not place a date-of-publication constraint. Hence, we have reviewed previous as well as most recent studies with the subject heading SLE in combination with each manifestation. Neutropenia can lead to morbidity and mortality from increased susceptibility to infection. Severe neutropenia can be successfully treated with granulocyte colony-stimulating factor. While related to disease activity, there is no specific therapy for lymphopenia. Severe lymphopenia may require the use of prophylactic therapy to prevent select opportunistic infections. Isolated idiopathic thrombocytopenic purpura maybe the first manifestation of SLE by months or even years. Some manifestations of lupus occur more frequently in association with low platelet count in these patients, for example, neuropsychiatric manifestation, haemolytic anaemia, the antiphospholipid syndrome and renal disease. Thrombocytopenia can be regarded as an important prognostic indicator of survival in patients with SLE. Medical, surgical and biological treatment modalities are reviewed for this manifestation. First-line therapy remains glucocorticoids. Through our review, we conclude glucocorticoids do produce a response in majority of patients initially, but sustained response to therapy is unlikely. Glucocorticoids are used as first-line therapy in patients with SLE with AIHA, but there is no conclusive evidence to guide second-line therapy. Rituximab is promising in refractory and non-responding AIHA. TTP is not recognised as a criteria for classification of SLE, but there is a considerable overlap between the presenting features of TTP and SLE, and a few patients with SLE have concurrent

  6. [Current views on oxygen transport from blood to tissues].

    PubMed

    Ivanov, K P

    2001-01-01

    During the recent 25-30 years, sophisticated experiments and mathematical simulation significantly changed the generally accepted theory of oxygen transport in tissue, which was based on two major postulates, namely: 1) Blood flows in capillaries continuously at uniform velocity, 2) Gas circulation between blood and tissue takes place exclusively in capillaries. As was shown by modern research techniques, blood flow in microvessels has irregular sharp velocity fluctuations in very short time intervals (seconds). In addition, mean velocity of blood flow in microvessels of the same caliber and the same micro-region of tissue may differ several times. Therefore, efficiency of microcirculation reactions may be assessed exclusively witH mean blood velocity in capillaries of the whole micro-region, and with complicated changes of the histogram of mean velocity distribution in capillaries. It was shown that arteriolas and venulas of inactive muscles and brain account for 30 to 50% of gas circulation between blood and tissue. This resulted in fundamental change of the previous postulates in the area of tissue gas circulation physiology, and, in effect, in replacement of oxygen transport paradigm created by A. Krog. This study is an attempt to present a new modern concept of oxygen transport in tissue, to show its research significance, and possible applications. PMID:11764645

  7. Oxygen nonstoichiometry and transport properties of strontium substituted lanthanum ferrite

    SciTech Connect

    Sogaard, Martin Vang Hendriksen, Peter; Mogensen, Mogens

    2007-04-15

    This study presents an investigation of the properties of (La{sub 0.6}Sr{sub 0.4}){sub 0.99}FeO{sub 3-{delta}} (LSF40) covering thermomechanical properties, oxygen nonstoichiometry and electronic and ionic conductivity. Finally, oxygen permeation experiments have been carried out and the oxygen flux has been determined as a function of temperature and driving force. The electrical conductivity was measured using a 4 probe method. It is shown that the electrical conductivity is a function of the charge carrier concentration only. The electron hole mobility is found to decrease with increasing charge carrier concentration in agreement with recent literature. Values of the chemical diffusion coefficient, D{sub Chem}, and the surface exchange coefficient, k{sub Ex}, have been determined using electrical conductivity relaxation. At 800 deg. CD{sub Chem} is determined to be 6.2x10{sup -6}cm{sup 2}s{sup -1} with an activation energy of 137kJmol{sup -1}. The surface exchange coefficient is found to decrease with decreasing oxygen partial pressure. Oxygen permeation experiments were carried out. The flux through a membrane placed between air and wet hydrogen/nitrogen was J{sub O{sub 2}}{approx}1.8x10{sup -6}molcm{sup -2}s{sup -1} (corresponding to an equivalent electrical current density of 670mAcm{sup -2}). The oxygen permeation measurements are successfully interpreted based on the oxygen nonstoichiometry data and the determined transport parameters.

  8. Oxygen transport properties estimation by DSMC-CT simulations

    SciTech Connect

    Bruno, Domenico; Frezzotti, Aldo; Ghiroldi, Gian Pietro

    2014-12-09

    Coupling DSMC simulations with classical trajectories calculations is emerging as a powerful tool to improve predictive capabilities of computational rarefied gas dynamics. The considerable increase of computational effort outlined in the early application of the method (Koura,1997) can be compensated by running simulations on massively parallel computers. In particular, GPU acceleration has been found quite effective in reducing computing time (Ferrigni,2012; Norman et al.,2013) of DSMC-CT simulations. The aim of the present work is to study rarefied Oxygen flows by modeling binary collisions through an accurate potential energy surface, obtained by molecular beams scattering (Aquilanti, et al.,1999). The accuracy of the method is assessed by calculating molecular Oxygen shear viscosity and heat conductivity following three different DSMC-CT simulation methods. In the first one, transport properties are obtained from DSMC-CT simulations of spontaneous fluctuation of an equilibrium state (Bruno et al, Phys. Fluids, 23, 093104, 2011). In the second method, the collision trajectory calculation is incorporated in a Monte Carlo integration procedure to evaluate the Taxman’s expressions for the transport properties of polyatomic gases (Taxman,1959). In the third, non-equilibrium zero and one-dimensional rarefied gas dynamic simulations are adopted and the transport properties are computed from the non-equilibrium fluxes of momentum and energy. The three methods provide close values of the transport properties, their estimated statistical error not exceeding 3%. The experimental values are slightly underestimated, the percentage deviation being, again, few percent.

  9. Oxygen transport in ceria: a first-principles study

    NASA Astrophysics Data System (ADS)

    Sergei, Simak

    2012-02-01

    Ceria (CeO2) is an important material for environmentally benign applications, ranging from solid-oxide fuel cells (SOFC) to oxygen storage [1-2]. The key characteristic needed to be improved is the mobility of oxygen ions. Optimization of ionic transport in ceria has been the topic of many studies. In particular, it has been discovered how the ionic conductivity in ceria might be improved by choosing the proper kind and concentration of dopants [3]. In this presentation we will approach the problem from a different direction by adjusting structural parameters of ceria via the change of external conditions. A systematic first-principles study of the energy landscape and kinetics of reduced ceria as a function of external parameters reveals a physically transparent way to improve oxygen transport in ceria. [4pt] [1] N. Skorodumova, S. Simak, B. Lundqvist, I. Abrikosov, and B. Johansson, Physical Review Letters 89, 14 (2002). [0pt] [2] A. Trovarelli, in Catalysis by Ceria and related materials (Imperial College Press, London, 2002). [0pt] [3] D. A. Andersson, S. I. Simak, N. V. Skorodumova, I. A.Abrikosov, and B. Johansson, Proceedings of the National Academy of Sciences of the United States of America 103, 3518 (2006).

  10. A model for oxygen transport and consumption in the unsaturated zone

    NASA Astrophysics Data System (ADS)

    Refsgaard, J. C.; Christensen, T. H.; Ammentorp, H. C.

    1991-12-01

    An oxygen transport and consumption model has been developed as a submodel to a general numerical model for solute transport in the unsaturated zone. The model comprises diffusive and convective transport of oxygen in soil air, convective transport and oxygen consumption in free water, and diffusive transport and a constant-rate oxygen consumption in the water-saturated soil crumbs. The model also estimates the anaerobic fraction of the water-saturated crumbs where no oxygen consumption takes place. The model dynamics and applicability are illustrated using the examples of the operation of a waste water infiltration plant and of anaerobic zones in the soil of importance for modelling denitrification.

  11. Oxygen transport is not compromised at high temperature in pythons.

    PubMed

    Fobian, Dannie; Overgaard, Johannes; Wang, Tobias

    2014-11-15

    To evaluate whether the 'oxygen and capacity limited thermal tolerance' model (OCLTT) applies to an air-breathing ectothermic vertebrate, we measured oxygen uptake (V̇(O₂)), cardiac performance and arterial blood gases during a progressive rise of temperature from 30 to 40°C in the snake Python regius. V̇(O₂) of fasting snakes increased exponentially with temperature whereas V̇(O₂) of digesting snakes at high temperatures plateaued at a level 3- to 4-fold above fasting. The high and sustained aerobic metabolism over the entire temperature range was supported by pronounced tachycardia at all temperatures, and both fasting and digesting snakes maintained a normal acid-base balance without any indication of anaerobic metabolism. All snakes also maintained high arterial PO2, even at temperatures close to the upper lethal temperature. Thus, there is no evidence of a reduced capacity for oxygen transport at high temperatures in either fasting or digesting snakes, suggesting that the upper thermal tolerance of this species is limited by other factors. PMID:25267848

  12. Improving haematology care in Wales.

    PubMed

    Perett, Shelagh

    2002-04-17

    Care for patients with a malignant haematological disorder in Wales has been revised significantly since the mid-1990s. Recommendations from expert groups stated that a uniformly high standard of care should be provided as close to the patient's home as possible and variations in practice that had been causing concern and distress to patients and their families be reduced. The All Wales Haematology Nurses Group was established to promote and disseminate standards and guidelines that would contribute to achieving these aims. The basis for the group's work was transformational leadership and collaborative practice. Work is ongoing and the group is planning to consolidate achievements to date through country-wide audit and professional education. PMID:11998241

  13. Bone biopsy in haematological disorders.

    PubMed Central

    Burkhardt, R; Frisch, B; Bartl, R

    1982-01-01

    Bone marrow biopsies are now widely used in the investigation and follow-up of many diseases. Semi-thin sections of 8216 undecalcified biopsies of patients with haematological disorders were studied. Observations were made on the cytopenias and the myelodysplastic syndromes, the acute leukaemias the myeloproliferative disorders, Hodgkin's disease and the malignant lymphomas including multiple myeloma, hairy cell leukaemia and angioimmunoblastic lymphadenopathy. Bone marrow biopsies are essential for the differential diagnosis of most cytopenias and for the early recognition of fibrosis which most frequently occurred as a consequence of megakaryocytic proliferation in the myeloproliferative disorders. Different patterns of bone marrow involvement were found in the lymphoproliferative disorders and both their type and extent constituted factors of prognostic significance. A survey of the literature is given and the conclusion is drawn that bone marrow biopsies provide indispensible information for the diagnostic evaluation and the follow-up of patients with haematological disorders. Images PMID:7040489

  14. Managing haematological disorders during pregnancy.

    PubMed

    Koh, Mickey B C; Lao, Zhen Tang; Rhodes, Elizabeth

    2013-12-01

    The management of patients with pre-existing haematological diseases during pregnancy can be particularly challenging. The potential maternal and foetal toxicities from treatment regimens including chemotherapy for malignant haematological disorders mean that joint management between obstetricians and haematologists is essential for achieving good outcomes for both mother and baby. Patients with inherited or acquired disorders of haemostasis including platelets (essential thrombocythaemia) and coagulation (antiphospholipid syndrome) resulting in a pro-thrombotic state also require special consideration as pregnancy is generally considered to be a pro-thrombotic condition which could exacerbate the pre-existing disorder. The choice, timing and duration of anticoagulation or anti-platelet therapy require careful coordination during the antenatal, perinatal as well as postnatal periods to ensure that both maternal and foetal risks are taken into consideration. Pregnancy in women with sickle cell disease has long been identified as high risk with medical and pregnancy related risks being more common compared to women without it. A range of foetal risks have also been reported but improvement in outcomes has been seen with better obstetric and haematological care and the emphasis on multidisciplinary teamwork. The meticulous management of iron overload and risks associated with repeated blood transfusions extends into the care of pregnant women with other haemoglobinopathies like thalassemias. PMID:24060203

  15. Global simulation of coupled carbon and oxygen transport in a Czochralski furnace for silicon crystal growth

    NASA Astrophysics Data System (ADS)

    Gao, B.; Kakimoto, K.

    2010-10-01

    For accurate prediction of carbon and oxygen impurities in a single crystal produced by the Czochralski method, global simulation of coupled oxygen and carbon transport in the whole furnace was implemented. Both gas-phase transportation and liquid-phase transportation of oxygen and carbon were considered. With five chemical reactions considered, SiO and CO concentrations in gas and C and O atom concentrations in silicon melt were solved simultaneously. The simulation results show good agreement with experimental data.

  16. The Pathway for Oxygen: Tutorial Modelling on Oxygen Transport from Air to Mitochondrion: The Pathway for Oxygen.

    PubMed

    Bassingthwaighte, James B; Raymond, Gary M; Dash, Ranjan K; Beard, Daniel A; Nolan, Margaret

    2016-01-01

    The 'Pathway for Oxygen' is captured in a set of models describing quantitative relationships between fluxes and driving forces for the flux of oxygen from the external air source to the mitochondrial sink at cytochrome oxidase. The intervening processes involve convection, membrane permeation, diffusion of free and heme-bound O2 and enzymatic reactions. While this system's basic elements are simple: ventilation, alveolar gas exchange with blood, circulation of the blood, perfusion of an organ, uptake by tissue, and consumption by chemical reaction, integration of these pieces quickly becomes complex. This complexity led us to construct a tutorial on the ideas and principles; these first PathwayO2 models are simple but quantitative and cover: (1) a 'one-alveolus lung' with airway resistance, lung volume compliance, (2) bidirectional transport of solute gasses like O2 and CO2, (3) gas exchange between alveolar air and lung capillary blood, (4) gas solubility in blood, and circulation of blood through the capillary syncytium and back to the lung, and (5) blood-tissue gas exchange in capillaries. These open-source models are at Physiome.org and provide background for the many respiratory models there. PMID:26782201

  17. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M; Kromer, Brian R; Litwin, Michael M; Rosen, Lee J; Christie, Gervase Maxwell; Wilson, Jamie R; Kosowski, Lawrence W; Robinson, Charles

    2014-01-07

    A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.

  18. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  19. Contributions of advective and diffusive oxygen transport through multilayer composite caps over mine waste.

    PubMed

    Kim, Hong; Benson, Craig H

    2004-07-01

    The relative contributions of four mechanisms of oxygen transport in multilayer composite (MLC) caps placed over oxygen-consuming mine waste were evaluated using numerical and analytical methods. MLC caps are defined here as caps consisting of earthen and geosynthetic (polymeric) components where a composite barrier layer consisting of a geomembrane (1-2 mm thick polymeric sheet) overlying a clay layer is the primary barrier to transport. The transport mechanisms that were considered are gas-phase advective transport, gas-phase diffusive transport, liquid-phase advective transport via infiltrating precipitation and liquid-phase diffusive transport. A numerical model was developed to simulate gas-phase advective-diffusive transport of oxygen through a multilayer cap containing seven layers. This model was also used to simulate oxygen diffusion in the liquid phase. An approximate analytical method was used to compute the advective flux of oxygen in the liquid phase. The numerical model was verified for limiting cases using an analytical solution. Comparisons were also made between model predictions and field data for earthen caps reported by others. Results of the analysis show that the dominant mechanism for oxygen transport through MLC caps is gas-phase diffusion. For the cases that were considered, the gas-phase diffusive flux typically comprises at least 99% of the total oxygen flux. Thus, designers of MLC caps should focus on design elements and features that will limit diffusion of gas-phase oxygen. PMID:15145567

  20. Oxygen transport in off-stoichiometric uranium dioxide mediated by defect clustering dynamics

    NASA Astrophysics Data System (ADS)

    Yu, Jianguo; Bai, Xian-Ming; El-Azab, Anter; Allen, Todd R.

    2015-03-01

    Oxygen transport is central to many properties of oxides such as stoichiometric changes, phase transformation, and ionic conductivity. In this paper, we report a mechanism for oxygen transport in uranium dioxide (UO2) in which the kinetics is mediated by defect clustering dynamics. In particular, the kinetic Monte Carlo method has been used to investigate the kinetics of oxygen transport in UO2 under the condition of creation and annihilation of oxygen vacancies and interstitials as well as oxygen interstitial clustering, with variable off-stoichiometry and temperature conditions. It is found that in hypo-stoichiometric UO2-x, oxygen transport is well described by the vacancy diffusion mechanism while in hyper-stoichiometric UO2+x, oxygen interstitial cluster diffusion contributes significantly to oxygen transport kinetics, particularly at high temperatures and high off-stoichiometry levels. It is also found that di-interstitial clusters and single interstitials play dominant roles in oxygen diffusion while other larger clusters have negligible contributions. However, the formation, coalescence, and dissociation of these larger clusters indirectly affects the overall oxygen diffusion due to their interactions with mono and di-interstitials, thus providing an explanation of the experimental observation of saturation or even drop of oxygen diffusivity at high off-stoichiometry.

  1. Oxygen transport in off-stoichiometric uranium dioxide mediated by defect clustering dynamics.

    PubMed

    Yu, Jianguo; Bai, Xian-Ming; El-Azab, Anter; Allen, Todd R

    2015-03-01

    Oxygen transport is central to many properties of oxides such as stoichiometric changes, phase transformation, and ionic conductivity. In this paper, we report a mechanism for oxygen transport in uranium dioxide (UO2) in which the kinetics is mediated by defect clustering dynamics. In particular, the kinetic Monte Carlo method has been used to investigate the kinetics of oxygen transport in UO2 under the condition of creation and annihilation of oxygen vacancies and interstitials as well as oxygen interstitial clustering, with variable off-stoichiometry and temperature conditions. It is found that in hypo-stoichiometric UO(2-x), oxygen transport is well described by the vacancy diffusion mechanism while in hyper-stoichiometric UO(2+x), oxygen interstitial cluster diffusion contributes significantly to oxygen transport kinetics, particularly at high temperatures and high off-stoichiometry levels. It is also found that di-interstitial clusters and single interstitials play dominant roles in oxygen diffusion while other larger clusters have negligible contributions. However, the formation, coalescence, and dissociation of these larger clusters indirectly affects the overall oxygen diffusion due to their interactions with mono and di-interstitials, thus providing an explanation of the experimental observation of saturation or even drop of oxygen diffusivity at high off-stoichiometry. PMID:25747097

  2. Oxygen transport in off-stoichiometric uranium dioxide mediated by defect clustering dynamics

    SciTech Connect

    Yu, Jianguo Bai, Xian-Ming; El-Azab, Anter; Allen, Todd R.

    2015-03-07

    Oxygen transport is central to many properties of oxides such as stoichiometric changes, phase transformation, and ionic conductivity. In this paper, we report a mechanism for oxygen transport in uranium dioxide (UO{sub 2}) in which the kinetics is mediated by defect clustering dynamics. In particular, the kinetic Monte Carlo method has been used to investigate the kinetics of oxygen transport in UO{sub 2} under the condition of creation and annihilation of oxygen vacancies and interstitials as well as oxygen interstitial clustering, with variable off-stoichiometry and temperature conditions. It is found that in hypo-stoichiometric UO{sub 2−x}, oxygen transport is well described by the vacancy diffusion mechanism while in hyper-stoichiometric UO{sub 2+x}, oxygen interstitial cluster diffusion contributes significantly to oxygen transport kinetics, particularly at high temperatures and high off-stoichiometry levels. It is also found that di-interstitial clusters and single interstitials play dominant roles in oxygen diffusion while other larger clusters have negligible contributions. However, the formation, coalescence, and dissociation of these larger clusters indirectly affects the overall oxygen diffusion due to their interactions with mono and di-interstitials, thus providing an explanation of the experimental observation of saturation or even drop of oxygen diffusivity at high off-stoichiometry.

  3. Oxygen transport in off-stoichiometric uranium dioxide mediated by defect clustering dynamics

    SciTech Connect

    Yu, Jianguo; Bai, Xian -Ming; El-Azab, Anter; Allen, Todd R.

    2015-03-05

    In this study, oxygen transport is central to many properties of oxides such as stoichiometric changes, phase transformation and ionic conductivity. In this paper, we report a mechanism for oxygen transport in uranium dioxide (UO2) in which the kinetics is mediated by defect clustering dynamics. In particular, the kinetic Monte Carlo (KMC) method has been used to investigate the kinetics of oxygen transport in UO2 under the condition of creation and annihilation of oxygen vacancies and interstitials as well as oxygen interstitial clustering, with variable offstoichiometry and temperature conditions. It is found that in hypo-stoichiometric UO2-x, oxygen transport is well described by the vacancy diffusion mechanism while in hyper-stoichiometric UO2+x, oxygen interstitial cluster diffusion contributes significantly to oxygen transport kinetics, particularly at high temperatures and high off-stoichiometry levels. It is also found that diinterstitial clusters and single interstitials play dominant roles in oxygen diffusion while other larger clusters have negligible contributions. However, the formation, coalescence and dissociation of these larger clusters indirectly affects the overall oxygen diffusion due to their interactions with mono and di-interstitials, thus providing a explanation of the experimental observation of saturation or even drop of oxygen diffusivity at high off-stoichiometry.

  4. Oxygen transport in off-stoichiometric uranium dioxide mediated by defect clustering dynamics

    DOE PAGESBeta

    Yu, Jianguo; Bai, Xian -Ming; El-Azab, Anter; Allen, Todd R.

    2015-03-05

    In this study, oxygen transport is central to many properties of oxides such as stoichiometric changes, phase transformation and ionic conductivity. In this paper, we report a mechanism for oxygen transport in uranium dioxide (UO2) in which the kinetics is mediated by defect clustering dynamics. In particular, the kinetic Monte Carlo (KMC) method has been used to investigate the kinetics of oxygen transport in UO2 under the condition of creation and annihilation of oxygen vacancies and interstitials as well as oxygen interstitial clustering, with variable offstoichiometry and temperature conditions. It is found that in hypo-stoichiometric UO2-x, oxygen transport is wellmore » described by the vacancy diffusion mechanism while in hyper-stoichiometric UO2+x, oxygen interstitial cluster diffusion contributes significantly to oxygen transport kinetics, particularly at high temperatures and high off-stoichiometry levels. It is also found that diinterstitial clusters and single interstitials play dominant roles in oxygen diffusion while other larger clusters have negligible contributions. However, the formation, coalescence and dissociation of these larger clusters indirectly affects the overall oxygen diffusion due to their interactions with mono and di-interstitials, thus providing a explanation of the experimental observation of saturation or even drop of oxygen diffusivity at high off-stoichiometry.« less

  5. Haemodynamic and oxygen transport response during exchange transfusion for severe falciparum malaria.

    PubMed

    Beards, S C; Joynt, G M; Lipman, J

    1994-11-01

    We describe the haemodynamic and oxygen transport response in a patient undergoing exchange transfusion for severe falciparum malaria. We found that exchange transfusion produced a significant increase in left ventricular stroke work index, systemic oxygen delivery and oxygen consumption. This potentially beneficial effect of exchange transfusion has not been reported previously. PMID:7824413

  6. Manipulating Cofactor Binding Thermodynamics in an Artificial Oxygen Transport Protein

    PubMed Central

    Zhang, Lei; Ross Anderson, J. L.; Ahmed, Ismail; Norman, Jessica A.; Negron, Christopher; Mutter, Andrew C.; Dutton, P. Leslie; Koder, Ronald L.

    2013-01-01

    We report the mutational analysis of an artificial oxygen transport protein, HP-7, which operates via a mechanism akin to human neuroglobin and cytoglobin. This protein destabilizes one of two heme-ligating histidine residues by coupling histidine side chain ligation with the burial of three charged glutamate residues on the same helix. Replacement of these glutamate residues with alanine, which is uncharged, increases the affinity of the distal histidine ligand by a factor of thirteen. Paradoxically, it also decreases heme binding affinity by a factor of five in the reduced state and sixty in the oxidized state. Application of a three-state binding model, in which an initial pentacoordinate binding event is followed by a protein conformational change to hexacoordinate, provides insight into the mechanism of this seemingly counterintuitive result: the initial pentacoordinate encounter complex is significantly destabilized by the loss of the glutamate side chains, and the increased affinity for the distal histidine only partially compensates. These results point to the importance of considering each oxidation and conformational state in the design of functional artificial proteins. PMID:22004125

  7. Oxygen Transport Across Space-Filling Biological Membranes

    NASA Astrophysics Data System (ADS)

    Hou, Chen

    2005-03-01

    Space-filling fractal surfaces play a fundamental role in how organisms function and in how structure determines function at various levels. In this project we developed an efficient and powerful algorithm, rope-walk algorithm, for solving diffusion equations of transport of species across the space-filling fractal surface. We performed analytic computations of the oxygen current across the alveolar membranes in the lung, as a function of diffusion coefficient and membrane permeability, using the rope-walk algorithm, without adjustable parameters. The analytic calculation identifies the four cases as sharply delineated screening regimes and finds that the lung operates in the partial-screening regime, close to the transition to no screening, and in the no-screening regime, for respiration at rest and in exercise respectively. The gas exchange satisfies six criteria of optimal design: maximum current; minimum waste of surface area; minimum permeability; maximum fault tolerance; minimum waiting time and maximum current increase when going from rest to exercise. This extraordinary, multiply optimized performance is a direct consequence of the space-filling membrane architecture.

  8. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation

    PubMed Central

    Gagnon, Louis; Smith, Amy F.; Boas, David A.; Devor, Anna; Secomb, Timothy W.; Sakadžić, Sava

    2016-01-01

    Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These “bottom-up” models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans.

  9. The Pathway for Oxygen: Tutorial Modelling on Oxygen Transport from Air to Mitochondrion

    PubMed Central

    Bassingthwaighte, James B.; Raymond, Gary M.; Dash, Ranjan K.; Beard, Daniel A.; Nolan, Margaret

    2016-01-01

    The ‘Pathway for Oxygen’ is captured in a set of models describing quantitative relationships between fluxes and driving forces for the flux of oxygen from the external air source to the mitochondrial sink at cytochrome oxidase. The intervening processes involve convection, membrane permeation, diffusion of free and heme-bound O2 and enzymatic reactions. While this system’s basic elements are simple: ventilation, alveolar gas exchange with blood, circulation of the blood, perfusion of an organ, uptake by tissue, and consumption by chemical reaction, integration of these pieces quickly becomes complex. This complexity led us to construct a tutorial on the ideas and principles; these first PathwayO2 models are simple but quantitative and cover: 1) a ‘one-alveolus lung’ with airway resistance, lung volume compliance, 2) bidirectional transport of solute gasses like O2 and CO2, 3) gas exchange between alveolar air and lung capillary blood, 4) gas solubility in blood, and circulation of blood through the capillary syncytium and back to the lung, and 5) blood-tissue gas exchange in capillaries. These open-source models are at Physiome.org and provide background for the many respiratory models there. PMID:26782201

  10. Cellular therapy for haematological malignancies.

    PubMed

    Roddie, P H; Turner, M L

    2002-11-01

    The aim of this review was to summarize the recent progress made in the field of cellular therapeutics in haematological malignancy. The review also examined the role that the National Transfusion Services might play in the manufacture of new cellular therapeutic agents, given both their expertise in the safe provision of blood products and their possession of accredited cell manipulation facilities. Cellular therapy is entering an era in which novel cellular products will find increasing clinical use, particularly in the areas of haematopoietic stem cell transplantation and immunotherapy. The production of novel cell-based therapies, both in Europe and North America, is now under strict regulatory control and therefore collaboration with the National Transfusion Services in the manufacture of these agents may well be beneficial if the production standards demanded by the regulatory authorities are to be fulfilled. PMID:12437515

  11. [Haematological adverse effects caused by psychiatric drugs].

    PubMed

    Mazaira, Silvina

    2008-01-01

    Almost all clases of psychiatric drugs (typical and atypical antipsychotics, antidepressants, mood stabilizers, benzodiazepines) have been reported as possible causes of haematological toxicity. This is a review of the literature in which different clinical situations involving red blood cells, white blood cells, platelets and impaired coagulation are detailed and the drugs more frequently involved are listed. The haematological adverse reactions detailed here include: aplastic anemia, haemolitic anemia, leukopenia, agranulocytosis, leukocytosis, eosinophilia, thrombocytosis, thrombocytopenia, disordered platelet function and impaired coagulation. The haematologic toxicity profile of the drugs more frequently involved: lithium, clozapine, carbamazepine, valproic acid and SSRI antidepressants is mentioned. PMID:19424521

  12. Effect of sepsis on skeletal muscle oxygen consumption and tissue oxygenation: interpreting capillary oxygen transport data using a mathematical model.

    PubMed

    Goldman, Daniel; Bateman, Ryon M; Ellis, Christopher G

    2004-12-01

    Inherent in the inflammatory response to sepsis is abnormal microvascular perfusion. Maldistribution of capillary red blood cell (RBC) flow in rat skeletal muscle has been characterized by increased 1) stopped-flow capillaries, 2) capillary oxygen extraction, and 3) ratio of fast-flow to normal-flow capillaries. On the basis of experimental data for functional capillary density (FCD), RBC velocity, and hemoglobin O2 saturation during sepsis, a mathematical model was used to calculate tissue O2 consumption (Vo2), tissue Po2 (Pt) profiles, and O2 delivery by fast-flow capillaries, which could not be measured experimentally. The model describes coupled capillary and tissue O2 transport using realistic blood and tissue biophysics and three-dimensional arrays of heterogeneously spaced capillaries and was solved numerically using a previously validated scheme. While total blood flow was maintained, capillary flow distribution was varied from 60/30/10% (normal/fast/stopped) in control to 33/33/33% (normal/fast/stopped) in average sepsis (AS) and 25/25/50% (normal/fast/stopped) in extreme sepsis (ES). Simulations found approximately two- and fourfold increases in tissue Vo2 in AS and ES, respectively. Average (minimum) Pt decreased from 43 (40) mmHg in control to 34 (27) and 26 (15) mmHg in AS and ES, respectively, and clustering fast-flow capillaries (increased flow heterogeneity) reduced minimum Pt to 14.5 mmHg. Thus, although fast capillaries prevented tissue dysoxia, they did not prevent increased hypoxia as the degree of microvascular injury increased. The model predicts that decreased FCD, increased fast flow, and increased Vo2 in sepsis expose skeletal muscle to significant regions of hypoxia, which could affect local cellular and organ function. PMID:15319199

  13. Modelling the effects of cerebral microvasculature morphology on oxygen transport

    PubMed Central

    Park, Chang Sub; Payne, Stephen J.

    2016-01-01

    The cerebral microvasculature plays a vital role in adequately supplying blood to the brain. Determining the health of the cerebral microvasculature is important during pathological conditions, such as stroke and dementia. Recent studies have shown the complex relationship between cerebral metabolic rate and transit time distribution, the transit times of all the possible pathways available dependent on network topology. In this paper, we extend a recently developed technique to solve for residue function, the amount of tracer left in the vasculature at any time, and transit time distribution in an existing model of the cerebral microvasculature to calculate cerebral metabolism. We present the mathematical theory needed to solve for oxygen concentration followed by results of the simulations. It is found that oxygen extraction fraction, the fraction of oxygen removed from the blood in the capillary network by the tissue, and cerebral metabolic rate are dependent on both mean and heterogeneity of the transit time distribution. For changes in cerebral blood flow, a positive correlation can be observed between mean transit time and oxygen extraction fraction, and a negative correlation between mean transit time and metabolic rate of oxygen. A negative correlation can also be observed between transit time heterogeneity and the metabolic rate of oxygen for a constant cerebral blood flow. A sensitivity analysis on the mean and heterogeneity of the transit time distribution was able to quantify their respective contributions to oxygen extraction fraction and metabolic rate of oxygen. Mean transit time has a greater contribution than the heterogeneity for oxygen extraction fraction. This is found to be opposite for metabolic rate of oxygen. These results provide information on the role of the cerebral microvasculature and its effects on flow and metabolism. They thus open up the possibility of obtaining additional valuable clinical information for diagnosing and treating

  14. Impact of microstructure on oxygen semi-permeation performance of perovskite membranes: Understanding of oxygen transport mechanisms

    NASA Astrophysics Data System (ADS)

    Reichmann, M.; Geffroy, P.-M.; Richet, N.; Chartier, T.

    2016-08-01

    The influence of dense membrane microstructures on semi permeation performance is still not well understood, and no consensus or explanation can be established from the literature. The apparent discrepancy is likely due to a poor understanding of the oxygen transport mechanisms through the membrane and, specifically, to the impact of the microstructure on the oxygen surface exchange kinetics. The aim of this paper is to provide a better understanding of the impact of microstructures on oxygen transport mechanisms through the membrane. Two reference materials, Ba0.5Sr0.5Fe0.7Co0.3O3 (BSFCo) and La0.5Sr0.5Fe0.7Ga0.3O3 (LSFG) perovskites, are considered to explain the discrepancies observed in the literature.

  15. 49 CFR 175.34 - Exceptions for cylinders of compressed oxygen or other oxidizing gases transported within the...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Exceptions for cylinders of compressed oxygen or... Exceptions for cylinders of compressed oxygen or other oxidizing gases transported within the State of Alaska. (a) Exceptions. When transported in the State of Alaska, cylinders of compressed oxygen or...

  16. Seasonal variations of haematological parameters in athletes.

    PubMed

    Banfi, Giuseppe; Lundby, Carsten; Robach, Paul; Lippi, Giuseppe

    2011-01-01

    The influence of training and competition workloads is crucial for evaluation of longitudinal haematological data in athletes. There are only a few papers on the variation of haematological parameters during long-lasting periods and, especially, during an entire competitive season. We summarized that some haematological parameters can be influenced by long-term training and competition periods. Haemoglobin (Hb) and haematocrit (Ht) are decreased during the more intense periods of training, throughout the season. In different sport disciplines, the decline of Hb ranges from 3 to 8% during the competition season, while the range of reticulocytes (Ret%) varies from 5 to 21%. Reticulocytes are also decreased after long periods of training and competitions, but their variation is not necessarily associated with that of Hb. The qualitative variations (trend of modifications) of haematological parameters are roughly independent of the sport discipline, but quantitatively (amount of modifications) dependent on sport discipline. The modifications are more evident in cycling, running, swimming than they are in football and rugby. The variations of haematological parameters within the same sport discipline are qualitatively concordant and quantitatively different among separate but consecutive competitive seasons. These findings are described in aerobic and team sports sportsmen. The definition of reliable reference ranges in sportsmen would only be possible by following the best laboratory practices. For antidoping purposes more studies investigating haematological modifications during the season are advisable. PMID:20842374

  17. PSYCHOLOGICAL ASPECTS OF HAEMATOLOGICAL MALIGNANCIES

    PubMed Central

    Kulhara, P.; Verma, S.C.; Bambery, P.; Nehra, R.

    1990-01-01

    SUMMMARY Sixty nine patients with various types of haematological malignancies were studied. Chronic myeloid leukaemia (n =32) was the commonest diagnosis. The patients were assessed on Hamilton Rating Scale for Depression, PGI-N2 Health Questionnaire and Presumptive Stressful Life Events Scale and those who had scores above the cut off points for Hamilton Rating Scale and/or PGI-N2 Health Questionnaire were assessed on Present State Examination. The patients were followed up at 3 and 6 months interval. At 3 months 51 patients were re-assessed whilst at 6 months only 26 could be re-evaluated. There were no significant changes in scores of Hamilton Rating scale and PGI-N2 Health Questionnaire at intake and subsequent follow-up assessments. No significant correlations between stressful life experience and severity of illness emerged. Twenty nine patients were interviewed on Present State Examination and of these 20 had diagnosable depressive neuroses- From consultation liaison psychiatric point of view, provision of psychiatric help to these patients is discussed. PMID:21927472

  18. Experimental study of dissolved oxygen transport by regular waves through a perforated breakwater

    NASA Astrophysics Data System (ADS)

    Yin, Zegao; Yu, Ning; Liang, Bingchen; Zeng, Jixiong; Xie, Shaohua

    2016-02-01

    The perforated breakwater is an environmentally friendly coastal structure, and dissolved oxygen concentration levels are an important index to denote water quality. In this paper, oxygen transport experiments with regular waves through a vertical perforated breakwater were conducted. The oxygen scavenger method was used to reduce the dissolved oxygen concentration of inner water body with the chemicals Na2SO3 and CoCl2. The dissolved oxygen concentration and wave parameters of 36 experimental scenarios were measured with different perforated arrangements and wave conditions. It was found that the oxygen transfer coefficient through wave surface, K1 a 1, is much lower than the oxygen transport coefficient through the perforated breakwater, K2 a 2. If the effect of K1 a 1 is not considered, the dissolved oxygen concentration computation for inner water body will not be greatly affected. Considering the effect of a permeable area ratio a, relative location parameter of perforations δ and wave period T, the aforementioned data of 30 experimental scenarios, the dimensional analysis and the least squares method were used to derive an equation of K2 a 2 (K2 a 2=0.0042 a 0.5 δ 0.2 T -1). It was validated with 6 other experimental scenarios data, which indicates an approximate agreement. Therefore, this equation can be used to compute the DO concentration caused by the water transport through perforated breakwater.

  19. Bacterial swimming and oxygen transport near contact lines

    NASA Astrophysics Data System (ADS)

    Tuval, Idan; Cisneros, Luis; Dombrowski, Christopher; Wolgemuth, Charles W.; Kessler, John O.; Goldstein, Raymond E.

    2005-02-01

    Aerobic bacteria often live in thin fluid layers near solid-air-water contact lines, in which the biology of chemotaxis, metabolism, and cell-cell signaling is intimately connected to the physics of buoyancy, diffusion, and mixing. Using the geometry of a sessile drop, we demonstrate in suspensions of Bacillus subtilis the self-organized generation of a persistent hydrodynamic vortex that traps cells near the contact line. Arising from upward oxygentaxis and downward gravitational forcing, these dynamics are related to the Boycott effect in sedimentation and are explained quantitatively by a mathematical model consisting of oxygen diffusion and consumption, chemotaxis, and viscous fluid dynamics. The vortex is shown to advectively enhance uptake of oxygen into the suspension, and the wedge geometry leads to a singularity in the chemotactic dynamics near the contact line. bioconvection | chemotaxis | singularity | Bacillus subtilis

  20. Concepts of oxygen transport at the microcirculatory level.

    PubMed

    Dewhirst, M W

    1998-07-01

    This article compares and contrasts the classic paradigms underlying the development of chronic and acute hypoxia in tumors. The classic theory of Thomlinson and Gray suggested that chronic hypoxia is the result of large intravascular distances. Newer evidence suggests that a multiplicity of effects contribute to this process, including steep longitudinal gradients of partial pressure of oxygen (Po2) along the vascular tree before arteriolar entry into tumor, rheologic effects on red cell deformability brought on by intravascular hypoxia, uneven distribution of red cell fluxes in microvessels leading to plasma channels, irregular vascular geometry, and oxygen demand that is out of balance with the supply. The most common theories have suggested that vascular stasis is the most common source of acute hypoxia. If this were true, the incidence of this form of hypoxia would be relatively rare because most studies indicate that total stasis probably occurs less than 5% of the time. Studies have suggested, however, that spontaneous fluctuation in tumor blood flow, on the microregional level, can lead to tissue hypoxia, and total vascular stasis is not required. Spontaneous fluctuations in flow and Po2 appear to occur commonly. Thus, the most current evidence suggests that tumor oxygenation is in a continuous state of flux. Collectively, this new information has important implications for therapy resistance and gene expression. PMID:9634491

  1. Thermodynamic, transport, and flow properties of gaseous products resulting from combustion of methane-air-oxygen

    NASA Technical Reports Server (NTRS)

    Klich, G. F.

    1976-01-01

    Results of calculations to determine thermodynamic, transport, and flow properties of combustion product gases are presented. The product gases are those resulting from combustion of methane-air-oxygen and methane-oxygen mixtures. The oxygen content of products resulting from the combustion of methane-air-oxygen mixtures was similiar to that of air; however, the oxygen contained in products of methane-oxygen combustion ranged from 20 percent by volume to zero for stoichiometric combustion. Calculations were made for products of reactant mixtures with fuel percentages, by mass, of 7.5 to 20. Results are presented for specific mixtures for a range of pressures varying from 0.0001 to 1,000 atm and for temperatures ranging from 200 to 3,800 K.

  2. A compartmental model for oxygen-carbon dioxide coupled transport in the microcirculation.

    PubMed

    Ye, G F; Moore, T W; Buerk, D G; Jaron, D

    1994-01-01

    We present a multicompartmental model for an oxygen-carbon dioxide transport system. The compartmental equations and their lumped parameters are derived through space averaging of the corresponding distributed model. The model can predict compartmental distributions of oxygen and carbon dioxide partial pressures, oxygen-hemoglobin saturation, and pH. Other unique features include the effects of the radial distribution of partial pressures and the difference in metabolic rates between vessel wall and tissue. A model for the cat brain, based on this formulation, is compared with results of experiments and with two types of earlier models: one without space averaging and one without carbon dioxide transport. The results suggest that space averaging the convective terms significantly affects the behavior of the model. This is consistent with conclusions from our earlier oxygen-only model. Our observations also demonstrate, however, significant differences between the results from the oxygen-carbon dioxide model and the oxygen-only model. For instance, at low blood flow rates or at low level of oxygen input, predicted oxygen partial pressures can differ by as much as 30% between the two models. Results obtained from the present model are supported by available experimental findings. PMID:7825749

  3. Membrane Transport of Singlet Oxygen Monitored by Dipole Potential Measurements

    PubMed Central

    Sokolov, Valerij S.; Pohl, Peter

    2009-01-01

    Abstract The efficiency of photodynamic reactions depends on 1), the penetration depth of the photosensitizer into the membrane and 2), the sidedness of the target. Molecules which are susceptible to singlet oxygen (1O2) experience less damage when separated from the photosensitizer by the membrane. Since 1O2 lifetime in the membrane environment is orders of magnitude longer than the time required for nonexcited oxygen (O2) to cross the membrane, this observation suggests that differences between the permeabilities or membrane partition of 1O2 and O2 exist. We investigated this hypothesis by releasing 1O2 at one side of a planar membrane while monitoring the kinetics of target damage at the opposite side of the same membrane. Damage to the target, represented by dipole-modifying molecules (phloretin or phlorizin), was indicated by changes in the interleaflet dipole potential difference Δϕb. A simple analytical model allowed estimation of the 1O2 interleaflet concentration difference from the rate at which Δϕb changed. It confirmed that the lower limit of 1O2 permeability is ∼2 cm/s; i.e., it roughly matches O2 permeability as predicted by Overton's rule. Consequently, the membrane cannot act as a barrier to 1O2 diffusion. Differences in the reaction rates at the cytoplasmic and extracellular membrane leaflets may be attributed only to 1O2 quenchers inside the membrane. PMID:18931253

  4. Plant hemoglobins: a molecular fossil record for the evolution of oxygen transport.

    PubMed

    Hoy, Julie A; Robinson, Howard; Trent, James T; Kakar, Smita; Smagghe, Benoit J; Hargrove, Mark S

    2007-08-01

    The evolution of oxygen transport hemoglobins occurred on at least two independent occasions. The earliest event led to myoglobin and red blood cell hemoglobin in animals. In plants, oxygen transport "leghemoglobins" evolved much more recently. In both events, pentacoordinate heme sites capable of inert oxygen transfer evolved from hexacoordinate hemoglobins that have unrelated functions. High sequence homology between hexacoordinate and pentacoordinate hemoglobins in plants has poised them for potential structural analysis leading to a molecular understanding of this important evolutionary event. However, the lack of a plant hexacoordinate hemoglobin structure in the exogenously ligand-bound form has prevented such comparison. Here we report the crystal structure of the cyanide-bound hexacoordinate hemoglobin from barley. This presents the first opportunity to examine conformational changes in plant hexacoordinate hemoglobins upon exogenous ligand binding, and reveals structural mechanisms for stabilizing the high-energy pentacoordinate heme conformation critical to the evolution of reversible oxygen binding hemoglobins. PMID:17560601

  5. Plant Hemoglobins: A Molecular Fossil Record for the Evolutin of Oxygen Transport

    SciTech Connect

    Hoy,J.; Robinson, H.; Trent, lll, J.; Kakar, S.; Smagghe, B.; Hargrove, M.

    2007-01-01

    The evolution of oxygen transport hemoglobins occurred on at least two independent occasions. The earliest event led to myoglobin and red blood cell hemoglobin in animals. In plants, oxygen transport 'leghemoglobins' evolved much more recently. In both events, pentacoordinate heme sites capable of inert oxygen transfer evolved from hexacoordinate hemoglobins that have unrelated functions. High sequence homology between hexacoordinate and pentacoordinate hemoglobins in plants has poised them for potential structural analysis leading to a molecular understanding of this important evolutionary event. However, the lack of a plant hexacoordinate hemoglobin structure in the exogenously ligand-bound form has prevented such comparison. Here we report the crystal structure of the cyanide-bound hexacoordinate hemoglobin from barley. This presents the first opportunity to examine conformational changes in plant hexacoordinate hemoglobins upon exogenous ligand binding, and reveals structural mechanisms for stabilizing the high-energy pentacoordinate heme conformation critical to the evolution of reversible oxygen binding hemoglobins.

  6. Oxygen transport deficits in systemic disease and implications for physical therapy.

    PubMed

    Dean, E

    1997-02-01

    The purposes of this article are to discuss the effects of some common systemic diseases on cardiopulmonary function and oxygen transport and to describe the implications for physical therapists. Pathology of every major organ system can manifest secondary effects on cardiopulmonary function and oxygen transport. Such effects are of considerable clinical significance given that they can be life threatening and that physical therapy usually stresses the oxygen transport system. This article reviews the cardiopulmonary effects of hematologic, neuromuscular, musculoskeletal, gastrointestinal, hepatic, renal, collagen vascular and connective tissue, endocrine, and immunologic conditions. The cardiopulmonary manifestations of some common nutritional disorders (eg, obesity, anorexia nervosa) are also discussed. Physical therapists need to be able to anticipate, detect, and manage the cardiopulmonary manifestations of systemic disease given medical advances and the increasing number of patients with multisystem problems, the aging of the population, the expanding scope of physical therapy practice, and the increased professional and ethical responsibility associated with direct patient access. PMID:9037219

  7. A dynamic model of oxygen transport from capillaries to tissue with moving red blood cells.

    PubMed

    Lücker, Adrien; Weber, Bruno; Jenny, Patrick

    2015-02-01

    Most oxygen required to support the energy needs of vertebrate tissues is delivered by diffusion from microvessels. The presence of red blood cells (RBCs) makes blood flow in the microcirculation highly heterogeneous. Additionally, flow regulation mechanisms dynamically respond to changes in tissue energy demand. These spatiotemporal variations directly affect the supply of oxygen to parenchymal cells. Due to various limiting assumptions, current models of oxygen transport cannot fully capture the consequences of complex hemodynamic effects on tissue oxygenation and are often not suitable for studying unsteady phenomena. With our new approach based on moving RBCs, the impact of blood flow heterogeneity on oxygen partial pressure (Po2) in the tissue can be quantified. Oxygen transport was simulated using parachute-shaped solid RBCs flowing through a capillary. With the use of a conical tissue domain with radii 19 and 13 μm, respectively, our computations indicate that Po2 at the RBC membrane exceeds Po2 between RBCs by 30 mmHg on average and that the mean plasma Po2 decreases by 9 mmHg over 50 μm. These results reproduce well recent intravascular Po2 measurements in the rodent brain. We also demonstrate that instantaneous variations of capillary hematocrit cause associated fluctuations of tissue Po2. Furthermore, our results suggest that homogeneous tissue oxygenation requires capillary networks to be denser on venular side than on arteriolar side. Our new model for oxygen transport will make it possible to quantify in detail the effects of blood flow heterogeneity on tissue oxygenation in realistic capillary networks. PMID:25398979

  8. A computational model of oxygen transport in the cerebrocapillary levels for normal and pathologic brain function

    PubMed Central

    Safaeian, Navid; David, Tim

    2013-01-01

    The oxygen exchange and correlation between the cerebral blood flow (CBF) and cerebral metabolic rate of oxygen consumption (CMRO2) in the cortical capillary levels for normal and pathologic brain functions remain the subject of debate. A 3D realistic mesoscale model of the cortical capillary network (non-tree like) is constructed using a random Voronoi tessellation in which each edge represents a capillary segment. The hemodynamics and oxygen transport are numerically simulated in the model, which involves rheological laws in the capillaries, oxygen diffusion, and non-linear binding of oxygen to hemoglobin, respectively. The findings show that the cerebral hypoxia due to a significant decreased perfusion (as can occur in stroke) can be avoided by a moderate reduction in oxygen demand. Oxygen extraction fraction (OEF) can be an important indicator for the brain oxygen metabolism under normal perfusion and misery-perfusion syndrome (leading to ischemia). The results demonstrated that a disproportionately large increase in blood supply is required for a small increase in the oxygen demand, which, in turn, is strongly dependent on the resting OEF. The predicted flow-metabolism coupling in the model supports the experimental studies of spatiotemporal stimulations in humans by positron emission tomography and functional magnetic resonance imaging. PMID:23921901

  9. [Massage and sophrology workshops for haematology professionals].

    PubMed

    Bannier, Christine; Sachot, Claudine; Simon, Armelle

    2014-04-01

    In haematology, the caregivers are confronted with the death of patients and the distress of their families. It is a working environment in which it is essential for the professionals to be taken care of in order to optimise the care provided to patients. At Nantes general hospital, massage and sophrology workshops enable the caregivers to recharge their batteries. PMID:24881242

  10. Erythropoiesis-stimulating agents and other methods to enhance oxygen transport.

    PubMed

    Elliott, S

    2008-06-01

    Oxygen is essential for life, and the body has developed an exquisite method to collect oxygen in the lungs and transport it to the tissues. Hb contained within red blood cells (RBCs), is the key oxygen-carrying component in blood, and levels of RBCs are tightly controlled according to demand for oxygen. The availability of oxygen plays a critical role in athletic performance, and agents that enhance oxygen delivery to tissues increase aerobic power. Early methods to increase oxygen delivery included training at altitude, and later, transfusion of packed RBCs. A breakthrough in understanding how RBC formation is controlled included the discovery of erythropoietin (Epo) and cloning of the EPO gene. Cloning of the EPO gene was followed by commercial development of recombinant human Epo (rHuEpo). Legitimate use of this and other agents that affect oxygen delivery is important in the treatment of anaemia (low Hb levels) in patients with chronic kidney disease or in cancer patients with chemotherapy-induced anaemia. However, competitive sports was affected by illicit use of rHuEpo to enhance performance. Testing methods for these agents resulted in a cat-and-mouse game, with testing labs attempting to detect the use of a drug or blood product to improve athletic performance (doping) and certain athletes developing methods to use the agents without being detected. This article examines the current methods to enhance aerobic performance and the methods to detect illicit use. PMID:18362898

  11. Assessing the performance of reactant transport layers and flow fields towards oxygen transport: A new imaging method based on chemiluminescence

    NASA Astrophysics Data System (ADS)

    Lopes, Thiago; Ho, Matthew; Kakati, Biraj K.; Kucernak, Anthony R. J.

    2015-01-01

    A new, simple and precise ex-situ optical imaging method is developed which allows indirect measurement of the partial pressure of oxygen (as ozone) within fuel cell components. Images of oxygen distribution are recorded with higher spatial (∼20 μm) and time (40 ms) resolutions. This approach is applied to assess oxygen concentration across the face of a pseudo polymer electrolyte fuel cell (PEFC), with a serpentine design flow field. We show that the amount of light produced is directly proportional to the partial pressure of ozone, in the same way as the local current density in a PEFC is proportional to the partial pressure of bimolecular oxygen. Hence the simulated system provides information relevant to a PEFC with the same geometry operating at the same stoichiometric ratio. This new approach allows direct imaging of flow under lands due to pressure gradients between the adjacent channels and non-laminar flow effects due to secondary flow around U-turns. These are major discoveries of fundamental importance in guiding materials development and in validating modelling studies. We find that contrary to many simulation papers, advection is an important mechanism in both the gas diffusion layer (more properly "reactant transport layer") and the microporous layer. Models which do not include these effects may underestimate reactant transport to the catalyst layer.

  12. Automated haematology analysis to diagnose malaria

    PubMed Central

    2010-01-01

    For more than a decade, flow cytometry-based automated haematology analysers have been studied for malaria diagnosis. Although current haematology analysers are not specifically designed to detect malaria-related abnormalities, most studies have found sensitivities that comply with WHO malaria-diagnostic guidelines, i.e. ≥ 95% in samples with > 100 parasites/μl. Establishing a correct and early malaria diagnosis is a prerequisite for an adequate treatment and to minimizing adverse outcomes. Expert light microscopy remains the 'gold standard' for malaria diagnosis in most clinical settings. However, it requires an explicit request from clinicians and has variable accuracy. Malaria diagnosis with flow cytometry-based haematology analysers could become an important adjuvant diagnostic tool in the routine laboratory work-up of febrile patients in or returning from malaria-endemic regions. Haematology analysers so far studied for malaria diagnosis are the Cell-Dyn®, Coulter® GEN·S and LH 750, and the Sysmex XE-2100® analysers. For Cell-Dyn analysers, abnormal depolarization events mainly in the lobularity/granularity and other scatter-plots, and various reticulocyte abnormalities have shown overall sensitivities and specificities of 49% to 97% and 61% to 100%, respectively. For the Coulter analysers, a 'malaria factor' using the monocyte and lymphocyte size standard deviations obtained by impedance detection has shown overall sensitivities and specificities of 82% to 98% and 72% to 94%, respectively. For the XE-2100, abnormal patterns in the DIFF, WBC/BASO, and RET-EXT scatter-plots, and pseudoeosinophilia and other abnormal haematological variables have been described, and multivariate diagnostic models have been designed with overall sensitivities and specificities of 86% to 97% and 81% to 98%, respectively. The accuracy for malaria diagnosis may vary according to species, parasite load, immunity and clinical context where the method is applied. Future

  13. Effect of nitric oxide on the transport and release of oxygen in fetal blood.

    PubMed

    Clementi, Maria Elisabetta; Orsini, Federica; Schininà, Maria Eugenia; Noia, Giuseppe; Giardina, Bruno

    2003-03-14

    It is well known that nitric oxide (NO), the most important vasodilator agent, plays an important role in lowering vascular resistance in the human umbilical-placental circulation and that its deficiency is related to the pathogenesis of pre-eclamptic disorder. Besides it has recently been demonstrated that human hemoglobin (HbA) is able to transport nitric oxide, as S-nitrosohemoglobin (SNO-Hb), from the arterial to the venous blood. In the present study we examine the functional properties of the adult and fetal nitrosated hemoglobins to see if the double transport of oxygen and NO may influence the fetal oxygenation and the relation between maternal and fetal blood. Our results show that S-nitrosation significantly increases the oxygen affinity of the adult Hb (HbA) with respect to native protein (no-nitrosated) while the functional properties of HbF are less influenced. The oxygen affinity modification, found for SNO-HbA, was ascribed to the nitrosation of cysteine beta 93: really, the same residue is also present in the gamma chains of fetal hemoglobin, while the increase of affinity is less evidenced; hence, it is probable that the 39 aminoacidic substitutions between beta and gamma chains allay the effects of S-nitrosation. As regards the physiological modulators (protons, chloride ions, 2,3-diphosphoglyceric acid, and temperature), they influence the oxygen affinity of the two hemoglobins S-nitrosated, in equal mode with respect to the native forms determining the same variation on the oxygen affinity. Hence, our results evidence the fact that the NO release by SNO-HbA "in vivo" would be limited to regions of extremely low oxygen tension (such as hypoxic regions), while in fetus, SNO-HbF would unload nitric oxide and oxygen at pressure values close to normal. PMID:12615064

  14. Cancer stem cells in haematological malignancies

    PubMed Central

    Golab, Jakub

    2015-01-01

    At least several types of human haematological malignancies can now be seen as ‘stem-cell diseases’. The best-studied in this context is acute myeloid leukaemia (AML). It has been shown that these diseases are driven by a pool of ‘leukaemia stem cells (LSC)’, which remain in the quiescent state, have the capacity to survive and self-renew, and are responsible for the recurrence of cancer after classical chemotherapy. It has been understood that LSC must be eliminated in order to cure patients suffering from haematological cancers. Recent advances in LSC research have allowed for description of LSC phenotype and identification of potential targets for anti-LSC therapies. This concise review summarises the current view on LSC biology and targeted approaches against LSC. PMID:25691816

  15. Pressure dependence of the oxygen reduction reaction at the platinum microelectrode/nafion interface - Electrode kinetics and mass transport

    NASA Technical Reports Server (NTRS)

    Parthasarathy, Arvind; Srinivasan, Supramaniam; Appleby, A. J.; Martin, Charles R.

    1992-01-01

    The investigation of oxygen reduction kinetics at the platinum/Nafion interface is of great importance in the advancement of proton-exchange-membrane (PEM) fuel-cell technology. This study focuses on the dependence of the oxygen reduction kinetics on oxygen pressure. Conventional Tafel analysis of the data shows that the reaction order with respect to oxygen is unity at both high and low current densities. Chronoamperometric measurements of the transport parameters for oxygen in Nafion show that oxygen dissolution follows Henry's isotherm. The diffusion coefficient of oxygen is invariant with pressure; however, the diffusion coefficient for oxygen is lower when air is used as the equilibrating gas as compared to when oxygen is used for equilibration. These results are of value in understanding the influence of O2 partial pressure on the performance of PEM fuel cells and also in elucidating the mechanism of oxygen reduction at the platinum/Nafion interface.

  16. Role of tumour angiogenesis in haematological malignancies.

    PubMed

    Medinger, Michael; Passweg, Jakob

    2014-01-01

    Tumour angiogenesis plays a key role in the pathogenesis and progression of haematological malignancies. Thereby, pro- and anti-angiogenic growth factors and cytokines regulate the angiogenic process. The most important growth factor, vascular endothelial growth factor (VEGF) and its signaling through its receptors 1 and 2, is not only involved in solid tumours, but there is also emerging evidence that tumour progression in haematological malignancies also depends on the induction of new blood vessel formation. The evidence supporting this theory includes the finding of increased bone marrow microvessel density and increased levels of plasma pro-angiogenic cytokines. Leukaemia cells interact with surrounding host cells and extracellular matrix, this crosstalk affecting the most important aspects of the malignant phenotype. The pathophysiology of leukaemia induced angiogenesis involves both direct production of angiogenic cytokines by leukaemia cells and their interaction with bone marrow microenvironment. The inhibition of VEGF signalling by monoclonal antibodies or small molecules (kinase inhibitors) has already been successfully used for the treatment of different cancer entities, and multiple new drugs are being tested. This review summarises recent advances in the basic understanding of the role of angiogenesis in haematological malignancies and the translation of such basic findings into clinical studies. PMID:25375891

  17. [Toward pertinent analytical objectives for haematological parameters].

    PubMed

    Iobagiu, Cristina; Nehar, Diane; Denis, Isabelle; de Saint-Trivier, Aurélie; Boyer, Michelle

    2014-01-01

    Usually, the blood cell counting activity in haematology laboratory uses the comparison of IQC values to the target values proposed by the manufacturer. We intended to improve the monitoring of the proper functioning of our analytical measure system for 17 main haematologic parameters. To set the allowable critical limits of IQC, we propose our reflection based on several elements: benchmark and expert recommendation, clinical requirements, statistical indicators of the laboratory calculated using IQC values (3 levels, 2 different lots, 2 haematology analysers and 2 passage modes) and the EEQ values, during four months. We exploited the reports obtained from the middleware (our own IQC values), and the interlaboratory comparison reports (obtained from SNCS and EuroCell websites) and we compared our performances to the Ricos objectives, to set clearly argued allowable limits for IQC values. Finally, the allowable limits correspond to the imprecision limits stated by Ricos for 14 parameters (desirable for 11 parametres and minimal for 3 parameters) and personalized limits (more exigent than desirable Ricos limits) for 3 parameters of blood cell counting. PMID:25486666

  18. Sex differences in circulatory oxygen transport parameters of sockeye salmon (Oncorhynchus nerka) on the spawning ground.

    PubMed

    Clark, Timothy Darren; Hinch, S G; Taylor, B D; Frappell, P B; Farrell, A P

    2009-07-01

    Upon reaching sexual maturity, several species of male salmonids possess a relative ventricular mass (rM(V)) that may be up to 90% larger than females. This can increase maximum cardiac stroke volume and power output, which may be beneficial to increasing the oxygen transport capacity of male salmonids during the spawning period. It may be further hypothesized, therefore, that other variables within the circulatory oxygen transport cascade, such as blood oxygen-carrying capacity and heart rate, are similarly enhanced in reproductively mature male salmonids. To test this idea, the present study measured a range of circulatory oxygen transport variables in wild male and female sockeye salmon (Oncorhynchus nerka) during their spawning period, following a 150 km migration from the ocean. The rM(V) of male fish was 13% greater than females. Conversely, the haemoglobin concentration ([Hb]) of female fish was 19% higher than males, indicative of a greater blood oxygen-carrying capacity (138 vs. 116 ml O2 l(-1), respectively). Surgically implanted physiological data loggers revealed a similar range in heart rate for both sexes on the spawning ground (20-80 beats min(-1) at 10 degrees C), with a tendency for male fish to spend a greater percentage of time (64%) than females (49%) at heart rates above 50 beats min(-1). Male fish on average consumed significantly more oxygen than females during a 13-h respirometry period. However, routine oxygen consumption rates (.)MO2 ranged between 1.5 and 8.5 mg min(-1) kg(-1) for both sexes, which implies that males did not inherently possess markedly higher routine aerobic energy demands, and suggests that the higher [Hb] of female fish may compensate for the smaller rM(V). These findings reject the hypothesis that all aspects of the circulatory oxygen transport cascade are inherently superior in male sockeye salmon. Instead, it is suggested that any differences in (.)MO2 between sexually mature male and female sockeye salmon can likely

  19. Oxygen transport in the internal xenon plasma of a dispenser hollow cathode

    NASA Astrophysics Data System (ADS)

    Capece, Angela M.; Polk, James E.; Mikellides, Ioannis G.; Shepherd, Joseph E.

    2014-04-01

    Reactive gases such as oxygen and water vapor modify the surface morphology of BaO dispenser cathodes and degrade the electron emission properties. For vacuum cathodes operating at fixed temperature, the emission current drops rapidly when oxygen adsorbs on top of the low work function surface. Previous experiments have shown that plasma cathodes are more resistant to oxygen poisoning and can operate with O2 partial pressures one to two orders of magnitude higher than vacuum cathodes before the onset of poisoning occurs. Plasma cathodes used for electric thrusters are typically operated with xenon; however, gas phase barium, oxygen, and tungsten species may be found in small concentrations. The densities of these minor species are small compared with the plasma density, and thus, their presence in the discharge does not significantly alter the xenon plasma parameters. It is important, however, to consider the transport of these minor species as they may deposit on the emitter surface and affect the electron emission properties. In this work, we present the results of a material transport model used to predict oxygen fluxes to the cathode surface by solving the species conservation equations in a cathode with a 2.25 mm diameter orifice operated at a discharge current of 15 A, a Xe flow rate of 3.7 sccm, and 100 ppm of O2. The dominant ionization process for O2 is resonant charge exchange with xenon ions. Ba is effectively recycled in the plasma; however, BaO and O2 are not. The model shows that the oxygen flux to the surface is not diffusion-limited; therefore, the high resistance to oxygen poisoning observed in plasma cathodes likely results from surface processes not considered here.

  20. Oxygen transport in the internal xenon plasma of a dispenser hollow cathode

    SciTech Connect

    Capece, Angela M. Shepherd, Joseph E.; Polk, James E.; Mikellides, Ioannis G.

    2014-04-21

    Reactive gases such as oxygen and water vapor modify the surface morphology of BaO dispenser cathodes and degrade the electron emission properties. For vacuum cathodes operating at fixed temperature, the emission current drops rapidly when oxygen adsorbs on top of the low work function surface. Previous experiments have shown that plasma cathodes are more resistant to oxygen poisoning and can operate with O{sub 2} partial pressures one to two orders of magnitude higher than vacuum cathodes before the onset of poisoning occurs. Plasma cathodes used for electric thrusters are typically operated with xenon; however, gas phase barium, oxygen, and tungsten species may be found in small concentrations. The densities of these minor species are small compared with the plasma density, and thus, their presence in the discharge does not significantly alter the xenon plasma parameters. It is important, however, to consider the transport of these minor species as they may deposit on the emitter surface and affect the electron emission properties. In this work, we present the results of a material transport model used to predict oxygen fluxes to the cathode surface by solving the species conservation equations in a cathode with a 2.25 mm diameter orifice operated at a discharge current of 15 A, a Xe flow rate of 3.7 sccm, and 100 ppm of O{sub 2}. The dominant ionization process for O{sub 2} is resonant charge exchange with xenon ions. Ba is effectively recycled in the plasma; however, BaO and O{sub 2} are not. The model shows that the oxygen flux to the surface is not diffusion-limited; therefore, the high resistance to oxygen poisoning observed in plasma cathodes likely results from surface processes not considered here.

  1. Oxygen isotopic transport and exchange during fluid flow: One-dimensional models and applications

    SciTech Connect

    Bowman, J.R. ); Willett, S.D. ); Cook, S.J. Environ Corp., Houston, TX )

    1994-01-01

    In this work the authors investigate the consequences of fluid flow and fluid-rock interaction to the isotopic evolution of fluids and rock with one-dimensional transport models of fluid flow and oxygen isotope exchange. Transport models dealing with stable isotopes are well established in recent geochemical literature. The authors extend previous treatments by presenting the derivation of both analytical and numerical solutions to the transport equations incorporating simultaneously advection, diffusion and hydrodynamic dispersion, and kinetics of isotopic exchange. The increased generality of numerical solutions allows the incorporation of other effects which control the spatial patterns of [delta][sup 18]O values developed in rocks and fluids including multiple reactive species and temperature gradients. The authors discuss the effects of flow parameters, conditions of isotopic exchange, and temperature gradients on the spatial patterns of isotopic shifts produced in rock sequences subjected to fluid flow, and on conventionally calculated W/R ratios for these rock sequences. Finally, the authors examine the implications of oxygen isotope transport for two natural systems where isotopic shifts or gradients could be interpreted in terms of unidirectional fluid infiltration. Solutions of one-dimensional transport equations including the mechanisms of advection, diffusion, hydrodynamic dispersion, and non-equilibrium exchange between water and rock indicate that the time-space evolution of oxygen isotopic compositions of rock and infiltrating fluid is dependent on (1) the rate of fluid infiltration, (2) the diffusive and dispersive properties of the rock matrix, (3) the rate of isotopic exchange, and (4) the rock-water mass oxygen ratio in a unit volume of water-saturated, porous rock. 56 refs., 18 figs., 2 tabs.

  2. Numerical simulation of oxygen transport during the CZ silicon crystal growth process

    NASA Astrophysics Data System (ADS)

    Chen, Jyh-Chen; Teng, Ying-Yang; Wun, Wan-Ting; Lu, Chung-Wei; Chen, Hsueh-I.; Chen, Chi-Yung; Lan, Wen-Chieh

    2011-03-01

    In this study, the effect of the flow motion and heat transfer generated by the crystal and crucible rotation on the oxygen distribution inside the melt during Czochralski silicon crystal growth is investigated. When the crucible rotates in a direction opposite to the crystal rotation, Taylor-Proundman vortices appear in the region below the crystal. The diffusion of oxygen impurity from the crucible wall to the crystal-melt interface is suppressed by these Taylor-Proundman vortices, while heat transport from the crucible wall to the crystal-melt interface is blocked by the Taylor-Proundman vortices. With a higher crucible rotation rate, the size of the Taylor-Proundman vortices increases and the size of the buoyancy-thermocapillary vortices decreases. This causes the temperature at the crucible wall to rise and the evaporation of oxygen impurity on the free surface to decrease. Hence, the amount of oxygen impurity that diffuses into the melt towards the crystal-melt interface increases. The suppression from the Taylor-Proundman vortices is dominant for the smaller crucible rotation rate, while the enhancement from the oxygen impurity diffusion prevails for the higher crucible rotation rate. Therefore, there is an optimum combination of crucible and crystal rotation for obtaining the lowest oxygen concentration.

  3. Bench-to-bedside review: Microvascular dysfunction in sepsis –hemodynamics, oxygen transport, and nitric oxide

    PubMed Central

    Bateman, Ryon M; Sharpe, Michael D; Ellis, Christopher G

    2003-01-01

    The microcirculation is a complex and integrated system that supplies and distributes oxygen throughout the tissues. The red blood cell (RBC) facilitates convective oxygen transport via co-operative binding with hemoglobin. In the microcirculation oxygen diffuses from the RBC into neighboring tissues, where it is consumed by mitochondria. Evidence suggests that the RBC acts as deliverer of oxygen and 'sensor' of local oxygen gradients. Within vascular beds RBCs are distributed actively by arteriolar tone and passively by rheologic factors, including vessel geometry and RBC deformability. Microvascular oxygen transport is determined by microvascular geometry, hemodynamics, and RBC hemoglobin oxygen saturation. Sepsis causes abnormal microvascular oxygen transport as significant numbers of capillaries stop flowing and the microcirculation fails to compensate for decreased functional capillary density. The resulting maldistribution of RBC flow results in a mismatch of oxygen delivery with oxygen demand that affects both critical oxygen delivery and oxygen extraction ratio. Nitric oxide (NO) maintains microvascular homeostasis by regulating arteriolar tone, RBC deformability, leukocyte and platelet adhesion to endothelial cells, and blood volume. NO also regulates mitochondrial respiration. During sepsis, NO over-production mediates systemic hypotension and microvascular reactivity, and is seemingly protective of microvascular blood flow. PMID:12974969

  4. Enhancing oxygen transport through Mixed-Ionic-and-Electronic-Conducting ceramic membranes

    NASA Astrophysics Data System (ADS)

    Yu, Anthony S.

    Ceramic membranes based on Mixed-Ionic-and-Electronic-Conducting (MIEC) oxides are capable of separating oxygen from air in the presence of an oxygen partial-pressure gradient. These MIEC membranes show great promise for oxygen consuming industrial processes, such as the production of syngas from steam reforming of natural gas (SRM), as well as for electricity generation in Solid Oxide Fuel Cells (SOFC). For both applications, the overall performance is dictated by the rate of oxygen transport across the membrane. Oxygen transport across MIEC membranes is composed of a bulk oxygen-ion diffusion process and surface processes, such as surface reactions and adsorption/desorption of gaseous reactants/products. The main goal of this thesis was to determine which process is rate-limiting in order to significantly enhance the overall rate of oxygen transport in MIEC membrane systems. The rate-limiting step was determined by evaluating the total resistance to oxygen transfer, Rtot. Rtot is the sum of a bulk diffusion resistance in the membrane itself, Rb, and interfacial loss components, Rs. Rb is a function of the membrane's ionic conductivity and thickness, while Rs arises primarily from slow surface-exchange kinetics that cause the P(O2) at the surfaces of the membrane to differ from the P(O 2) in the adjacent gas phases. Rtot can be calculated from the Nernst potential across the membrane and the measured oxygen flux. The rate-limiting process can be determined by evaluating the relative contributions of the various losses, Rs and Rb, to Rtot. Using this method, this thesis demonstrates that for most membrane systems, Rs is the dominating factor. In the development of membrane systems with high oxygen transport rates, thin membranes with high ionic conductivities are required to achieve fast bulk oxygen-ion diffusion. However, as membrane thickness is decreased, surface reaction kinetics become more important in determining the overall transport rate. The two

  5. O2 and CO2 glow-discharge-assisted oxygen transport through Ag

    NASA Astrophysics Data System (ADS)

    Outlaw, R. A.

    1990-08-01

    The permeation of oxygen through Ag normally occurs by a sequence of steps which include the initial dissociative adsorption of molecular oxygen at the upstream surface, the dissolution of the atoms into the bulk, and the subsequent migration of the atoms between octahedral sites of the lattice until they arrive at the vacuum interface downstream. The dissociative adsorption step, however, proceeds slowly, as indicated by the low sticking coefficient of O2 on Ag(10-6-10-3). The application of a dc field in 0.5 Torr of O2 (E/n˜10-14 V cm2) on the upstream side of a Ag membrane generated gas phase atomic oxygen that substantially enhanced the transport. The transport flux was observed to increase from a value of 4.4×1013 cm-2 s-1 to a glow discharge value of 2.83×1014 cm-2 s-1 at a membrane temperature of 650 °C. This suggests that the dissociative adsorption step limits the supply of oxygen atoms to the upstream side of the membrane. When the upstream O2 was replaced by an equal pressure of CO2, only a small permeation signal was observed, but the application of the glow discharge substantially increased the transport flux from 3.25×1012 cm-2 s-1 to 1.74×1014 cm-2 s-1. This method of separating O2 from a CO2 environment may be a possible mechanism for providing a supply of oxygen for astronauts in a manned mission to Mars.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    PubMed

    Muñoz-García, Ana B; Ritzmann, Andrew M; Pavone, Michele; Keith, John A; Carter, Emily A

    2014-11-18

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

  8. Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: considerations on oxygen transport.

    PubMed

    Biasetti, Jacopo; Spazzini, Pier Giorgio; Hedin, Ulf; Gasser, T Christian

    2014-08-01

    Shear-induced migration of red blood cells (RBCs) is a well-known phenomenon characterizing blood flow in the small vessels (micrometre to millimetre size) of the cardiovascular system. In large vessels, like the abdominal aorta and the carotid artery (millimetre to centimetre size), the extent of this migration and its interaction with secondary flows has not been fully elucidated. RBC migration exerts its influence primarily on platelet concentration, oxygen transport and oxygen availability at the luminal surface, which could influence vessel wall disease processes in and adjacent to the intima. Phillips' shear-induced particle migration model, coupled to the Quemada viscosity model, was employed to simulate the macroscopic behaviour of RBCs in four patient-specific geometries: a normal abdominal aorta, an abdominal aortic aneurysm (AAA), a normal carotid bifurcation and a stenotic carotid bifurcation. Simulations show a migration of RBCs from the near-wall region with a lowering of wall haematocrit (volume fraction of RBCs) on the posterior side of the normal aorta and on the lateral-external side of the iliac arteries. A marked migration is observed on the outer wall of the carotid sinus, along the common carotid artery and in the carotid stenosis. No significant migration is observed in the AAA. The spatial and temporal patterns of wall haematocrit are correlated with the near-wall shear layer and with the secondary flows induced by the vessel curvature. In particular, secondary flows accentuate the initial lowering in RBC near-wall concentration by convecting RBCs from the inner curvature side to the outer curvature side. The results reinforce data in literature showing a decrease in oxygen partial pressure on the inner curvature wall of the carotid sinus induced by the presence of secondary flows. The lowering of wall haematocrit is postulated to induce a decrease in oxygen availability at the luminal surface through a diminished concentration of

  9. Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: considerations on oxygen transport

    PubMed Central

    Biasetti, Jacopo; Spazzini, Pier Giorgio; Hedin, Ulf; Gasser, T. Christian

    2014-01-01

    Shear-induced migration of red blood cells (RBCs) is a well-known phenomenon characterizing blood flow in the small vessels (micrometre to millimetre size) of the cardiovascular system. In large vessels, like the abdominal aorta and the carotid artery (millimetre to centimetre size), the extent of this migration and its interaction with secondary flows has not been fully elucidated. RBC migration exerts its influence primarily on platelet concentration, oxygen transport and oxygen availability at the luminal surface, which could influence vessel wall disease processes in and adjacent to the intima. Phillips' shear-induced particle migration model, coupled to the Quemada viscosity model, was employed to simulate the macroscopic behaviour of RBCs in four patient-specific geometries: a normal abdominal aorta, an abdominal aortic aneurysm (AAA), a normal carotid bifurcation and a stenotic carotid bifurcation. Simulations show a migration of RBCs from the near-wall region with a lowering of wall haematocrit (volume fraction of RBCs) on the posterior side of the normal aorta and on the lateral-external side of the iliac arteries. A marked migration is observed on the outer wall of the carotid sinus, along the common carotid artery and in the carotid stenosis. No significant migration is observed in the AAA. The spatial and temporal patterns of wall haematocrit are correlated with the near-wall shear layer and with the secondary flows induced by the vessel curvature. In particular, secondary flows accentuate the initial lowering in RBC near-wall concentration by convecting RBCs from the inner curvature side to the outer curvature side. The results reinforce data in literature showing a decrease in oxygen partial pressure on the inner curvature wall of the carotid sinus induced by the presence of secondary flows. The lowering of wall haematocrit is postulated to induce a decrease in oxygen availability at the luminal surface through a diminished concentration of

  10. Role of reactive oxygen species in regulation of glucose transport in skeletal muscle during exercise.

    PubMed

    Katz, Abram

    2016-06-01

    Glucose derived from extracellular sources serves as an energy source in virtually all eukaryotic cells, including skeletal muscle. Its contribution to energy turnover increases with exercise intensity up to moderately heavy workloads. However, at very high workloads, the contribution of extracellular glucose to energy turnover is negligible, despite the high rate of glucose transport. Reactive oxygen species (ROS) are involved in the stimulation of glucose transport in isolated skeletal muscle preparations during intense repeated contractions. Consistent with this observation, heavy exercise is associated with significant production of ROS. However, during more mild to moderate stimulation or exercise conditions (in vitro, in situ and in vivo) antioxidants do not affect glucose transport. It is noteworthy that the production of ROS is limited or not observed under these conditions and that the concentration of the antioxidant used was extremely low. The results to date suggest that ROS involvement in activation of glucose transport occurs primarily during intense short-term exercise and that other mechanisms are involved during mild to moderate exercise. What remains puzzling is why ROS-mediated activation of glucose transport would occur under conditions where glucose transport is highest and utilization (i.e. phosphorylation of glucose by hexokinase) is low. Possibly ROS production is involved in priming glucose transport during heavy exercise to accelerate glycogen biogenesis during the initial recovery period after exercise, as well as altering other aspects of intracellular metabolism. PMID:26791627

  11. Simulation of oxygen carrier mediated oxygen transport to C3A hepatoma cells housed within a hollow fiber bioreactor.

    PubMed

    Sullivan, Jesse P; Gordon, Jason E; Palmer, Andre F

    2006-02-01

    A priori knowledge of the dissolved oxygen (O2) concentration profile within a hepatic hollow fiber (HF) bioreactor is important in developing an effective bioartificial liver assist device (BLAD). O2 provision is limiting within HF bioreactors and we hypothesize that supplementing a hepatic HF bioreactor's circulating media with bovine red blood cells (bRBCs), which function as an O2 carrier, will improve oxygenation. The dissolved O2 concentration profile within a single HF (lumen, membrane, and representative extra capillary space (ECS)) was modeled with the finite element method, and compared to experimentally measured data obtained on an actual HF bioreactor with the same dimensions housing C3A hepatoma cells. Our results (experimental and modeling) indicate bRBC supplementation of the circulating media leads to an increase in O2 consumed by C3A cells. Under certain experimental conditions (pO2,IN) = 95 mmHg, Q = 8.30 mL/min), the addition of bRBCs at 5% of the average in vivo human red blood cell concentration (% hRBC) results in approximately 50% increase in the O2 consumption rate (OCR). By simply adjusting the operating conditions (pO2,IN) = 25 mmHg, Q = 1.77 mL/min) and increasing bRBC concentration to 25% hRBC the OCR increase is approximately 10-fold. However, the improved O2 concentration profile experienced by the C3A cells could not duplicate the full range of in vivo O2 tensions (25-70 mmHg) typically experienced within the liver sinusoid with this particular HF bioreactor. Nonetheless, we demonstrate that the O2 transport model accurately predicts O2 consumption within a HF bioreactor, thus setting up the modeling framework for improving the design of future hepatic HF bioreactors. PMID:16161160

  12. Study of the oxygen transport through Ag (110), Ag (poly), and Ag 2.0 Zr

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Wu, D.; Davidson, M. R.; Hoflund, Gar B.

    1992-01-01

    The transport of oxygen through high-purity membranes of Ag (110), Ag (poly), Ag (nano), and Ag 2.0 Zr has been studied by an ultrahigh vacuum permeation method over the temperature range of 400-800 C. The data show that there are substantial deviations from ordinary diffusion-controlled transport. A surface limitation has been confirmed by glow-discharge studies where the upstream O2 supply has been partially converted to atoms, which, for the same temperature and pressure, gave rise to over an order of magnitude increase in transport flux. Further, the addition of 2.0 wt percent Zr to the Ag has provided increased dissociative adsorption rates, which, in turn, increased the transport flux by a factor of 2. It was also observed that below a temperature of 630 C, the diffusivity exhibits an increase in activation energy of over 4 kcal/mol, which has been attributed to trapping of the atomic oxygen and/or kinetic barriers at the surface and subsurface of the vacuum interface. Above 630 C, the activation barrier decreases to the accepted value of about 11 kcal/mol for Ag (poly), consistent with zero concentration at the vacuum interface.

  13. Hazardous Off-Gassing of Carbon Monoxide and Oxygen Depletion during Ocean Transportation of Wood Pellets

    PubMed Central

    Svedberg, Urban; Samuelsson, Jerker; Melin, Staffan

    2008-01-01

    Five ocean vessels were investigated for the characterization and quantification of gaseous compounds emitted during ocean transportation of wood pellets in closed cargo hatches from Canada to Sweden. The study was initiated after a fatal accident with several injured during discharge in Sweden. The objective with the investigation was to better understand the off-gassing and issues related to workers' exposure. Air sampling was done during transport and immediately before discharge in the undisturbed headspace air above the wood pellets and in the staircase adjacent to each hatch. The samples were analyzed with Fourier transform infrared spectroscopy and direct reading instruments. The following compounds and ranges were detected in samples from the five ships: carbon monoxide (CO) 1460–14650 ppm, carbon dioxide (CO2) 2960–21570 ppm, methane 79.9–956 ppm, butane equivalents 63–842 ppm, ethylene 2–21.2 ppm, propylene 5.3–36 ppm, ethane 0–25 ppm and aldehydes 2.3–35 ppm. The oxygen levels were between 0.8 and 16.9%. The concentrations in the staircases were almost as high as in the cargo hatches, indicating a fairly free passage of air between the two spaces. A potentially dangerous atmosphere was reached within a week from loading. The conclusions are that ocean transportation of wood pellets in confined spaces may produce an oxygen deficient atmosphere and lethal levels of CO which may leak into adjacent access spaces. The dangerous combination of extremely high levels of CO and reduced oxygen produces a fast-acting toxic combination. Measurement of CO in combination with oxygen is essential prior to entry in spaces having air communication with cargo hatches of wood pellets. Forced ventilation of staircases prior to entry is necessary. Redesign, locking and labeling of access doors and the establishment of rigorous entry procedures and training of onboard crew as well as personnel boarding ocean vessels are also important. PMID:18397907

  14. Impact of renal medullary three-dimensional architecture on oxygen transport.

    PubMed

    Fry, Brendan C; Edwards, Aurélie; Sgouralis, Ioannis; Layton, Anita T

    2014-08-01

    We have developed a highly detailed mathematical model of solute transport in the renal medulla of the rat kidney to study the impact of the structured organization of nephrons and vessels revealed in anatomic studies. The model represents the arrangement of tubules around a vascular bundle in the outer medulla and around a collecting duct cluster in the upper inner medulla. Model simulations yield marked gradients in intrabundle and interbundle interstitial fluid oxygen tension (PO2), NaCl concentration, and osmolality in the outer medulla, owing to the vigorous active reabsorption of NaCl by the thick ascending limbs. In the inner medulla, where the thin ascending limbs do not mediate significant active NaCl transport, interstitial fluid composition becomes much more homogeneous with respect to NaCl, urea, and osmolality. Nonetheless, a substantial PO2 gradient remains, owing to the relatively high oxygen demand of the inner medullary collecting ducts. Perhaps more importantly, the model predicts that in the absence of the three-dimensional medullary architecture, oxygen delivery to the inner medulla would drastically decrease, with the terminal inner medulla nearly completely deprived of oxygen. Thus model results suggest that the functional role of the three-dimensional medullary architecture may be to preserve oxygen delivery to the papilla. Additionally, a simulation that represents low medullary blood flow suggests that the separation of thick limbs from the vascular bundles substantially increases the risk of the segments to hypoxic injury. When nephrons and vessels are more homogeneously distributed, luminal PO2 in the thick ascending limb of superficial nephrons increases by 66% in the inner stripe. Furthermore, simulations predict that owing to the Bohr effect, the presumed greater acidity of blood in the interbundle regions, where thick ascending limbs are located, relative to that in the vascular bundles, facilitates the delivery of O2 to support the

  15. Constraints on oceanic meridional heat transport from combined measurements of oxygen and carbon

    NASA Astrophysics Data System (ADS)

    Resplandy, L.; Keeling, R. F.; Stephens, B. B.; Bent, J. D.; Jacobson, A.; Rödenbeck, C.; Khatiwala, S.

    2016-02-01

    Despite its importance to the climate system, the ocean meridional heat transport is still poorly quantified. We identify a strong link between the northern hemisphere deficit in atmospheric potential oxygen (APO = O_2 + 1.1 × CO_2 ) and the asymmetry in meridional heat transport between northern and southern hemispheres. The recent aircraft observations from the HIPPO campaign reveal a northern APO deficit in the tropospheric column of - 10.4 ± 1.0 per meg, double the value at the surface and more representative of large-scale air-sea fluxes. The global northward ocean heat transport asymmetry necessary to explain the observed APO deficit is about 0.7-1.1 PW, which corresponds to the upper range of estimates from hydrographic sections and atmospheric reanalyses.

  16. Pediatric Extracorporeal Membrane Oxygenation Transport by EC-145 With a Custom-Built Sled.

    PubMed

    Holt, Philip L; Hodge, Ashley B; Ratliff, Todd; Frazier, W Joshua; Ohnesorge, David; Gee, Samantha W

    2016-01-01

    Indications for the use of extracorporeal membrane oxygenation (ECMO) in pediatrics has expanded beyond the initial historic treatment of neonates with respiratory failure. Patients with severe refractory cardiopulmonary failure may benefit from ECMO support until the primary insult has subsided or been treated. More recently, ECMO has been used by some centers as a bridge to transplant for irreversible organ failure. Nationwide Children's Hospital is a referral center that supports the use of ECMO as a bridge to transplant and is able to provide transport services for ECMO patients referred for transplant evaluation. In this report, we describe our design of a unique, custom-built sled designed specifically for the EC-145 helicopter to transport pediatric ECMO patients to our institution. This report is the first, to our knowledge, to describe the safe and successful transport of a pediatric ECMO patient in an EC-145 helicopter. PMID:27255881

  17. Gas Transport Resistance in Polymer Electrolyte Thin Films on Oxygen Reduction Reaction Catalysts.

    PubMed

    Liu, Hang; Epting, William K; Litster, Shawn

    2015-09-15

    Significant reductions in expensive platinum catalyst loading for the oxygen reduction reaction are needed for commercially viable fuel cell electric vehicles as well as other important applications. In reducing loading, a resistance at the Pt surface in the presence of thin perfluorosulfonic acid (PFSA) electrolyte film, on the order of 10 nm thick, becomes a significant barrier to adequate performance. However, the resistance mechanism is unresolved and could be due to gas dissolution kinetics, increased diffusion resistance in thin films, or electrolyte anion interactions. A common hypothesis for the origin of the resistance is a highly reduced oxygen permeability in the thin polymer electrolyte films that coat the catalyst relative to bulk permeability that is caused by nanoscale confinement effects. Unfortunately, the prior work has not separated the thin-film gas transport resistance from that associated with PFSA interactions with a polarized catalyst surface. Here, we present the first characterization of the thin-film O2 transport resistance in the absence of a polarized catalyst, using a nanoporous substrate that geometrically mimics the active catalyst particles. Through a parametric study of varying PFSA film thickness, as thin as 50 nm, we observe no enhanced gas transport resistance in thin films as a result of either interfacial effects or structural changes in the PFSA. Our results suggest that other effects, such as anion poisoning at the Pt catalyst, could be the source of the additional resistance observed at low Pt loading. PMID:26299282

  18. Membrane transporters mediating root signalling and adaptive responses to oxygen deprivation and soil flooding.

    PubMed

    Shabala, Sergey; Shabala, Lana; Barcelo, Juan; Poschenrieder, Charlotte

    2014-10-01

    This review provides a comprehensive assessment of a previously unexplored topic: elucidating the role that plasma- and organelle-based membrane transporters play in plant-adaptive responses to flooding. We show that energy availability and metabolic shifts under hypoxia and anoxia are critical in regulating membrane-transport activity. We illustrate the high tissue and time dependence of this regulation, reveal the molecular identity of transporters involved and discuss the modes of their regulation. We show that both reduced oxygen availability and accumulation of transition metals in flooded roots result in a reduction in the cytosolic K(+) pool, ultimately determining the cell's fate and transition to programmed cell death (PCD). This process can be strongly affected by hypoxia-induced changes in the amino acid pool profile and, specifically, ϒ-amino butyric acid (GABA) accumulation. It is suggested that GABA plays an important regulatory role, allowing plants to proceed with H2 O2 signalling to activate a cascade of genes that mediate plant adaptation to flooding while at the same time, preventing the cell from entering a 'suicide program'. We conclude that progress in crop breeding for flooding tolerance can only be achieved by pyramiding the numerous physiological traits that confer efficient energy maintenance, cytosolic ion homeostasis, and reactive oxygen species (ROS) control and detoxification. PMID:24689809

  19. Modelling the oxygen cost of transport in competitions over ground of variable slope.

    PubMed

    Schroter, R C; Marlin, D J

    2002-09-01

    This study provides an objective method for estimating the oxygen consumption of horses while running on variable slopes so that realistic comparisons may be made of the locomotory transport cost involved in 3-day events, particularly the Speed and Endurance Test, at sites of differing terrain. A knowledge of the work profile over a particular course would enable competitors to plan speed and interval times appropriately along its length. We have developed a semi-empirical, but mechanistically based, model to calculate the oxygen cost of transport [COTpath in ml O2/kg/m path] for running on the flat, up or down a slope of given gradient (from -0.3 to +0.3). The model is then used to calculate the overall effort of running on a number of 3-day event courses of differing standard; the model does not assess the energetic cost of jumping. The cost of transport over the range of gradient of -0.3 to +0.3 was modelled using the following equations: On the flat or uphill: COTpath = 0.123 + 1.561(gradient); Downhill: COTpath = 0.123 + 1.591(gradient) + 9.762(gradient)2 + 14.0(gradient)3. PMID:12405723

  20. Diffusive flux in a model of stochastically gated oxygen transport in insect respiration

    NASA Astrophysics Data System (ADS)

    Berezhkovskii, Alexander M.; Shvartsman, Stanislav Y.

    2016-05-01

    Oxygen delivery to insect tissues is controlled by transport through a branched tubular network that is connected to the atmosphere by valve-like gates, known as spiracles. In certain physiological regimes, the spiracles appear to be randomly switching between open and closed states. Quantitative analysis of this regime leads a reaction-diffusion problem with stochastically switching boundary condition. We derive an expression for the diffusive flux at long times in this problem. Our approach starts with the derivation of the passage probability for a single particle that diffuses between a stochastically gated boundary, which models the opening and closing spiracle, and the perfectly absorbing boundary, which models oxygen absorption by the tissue. This passage probability is then used to derive an expression giving the diffusive flux as a function of the geometric parameters of the tube and characteristic time scales of diffusion and gate dynamics.

  1. Diffusive flux in a model of stochastically gated oxygen transport in insect respiration.

    PubMed

    Berezhkovskii, Alexander M; Shvartsman, Stanislav Y

    2016-05-28

    Oxygen delivery to insect tissues is controlled by transport through a branched tubular network that is connected to the atmosphere by valve-like gates, known as spiracles. In certain physiological regimes, the spiracles appear to be randomly switching between open and closed states. Quantitative analysis of this regime leads a reaction-diffusion problem with stochastically switching boundary condition. We derive an expression for the diffusive flux at long times in this problem. Our approach starts with the derivation of the passage probability for a single particle that diffuses between a stochastically gated boundary, which models the opening and closing spiracle, and the perfectly absorbing boundary, which models oxygen absorption by the tissue. This passage probability is then used to derive an expression giving the diffusive flux as a function of the geometric parameters of the tube and characteristic time scales of diffusion and gate dynamics. PMID:27250273

  2. Oxygen transport pathways in Ruddlesden–Popper structured oxides revealed via in situ neutron diffraction

    DOE PAGESBeta

    Tomkiewicz, Alex C.; Tamimi, Mazin; Huq, Ashfia; McIntosh, Steven

    2015-09-21

    Ruddlesden-Popper structured oxides, general form An+1BnO3n+1, consist of n-layers of the perovskite structure stacked in between rock-salt layers, and have potential application in solid oxide electrochemical cells and ion transport membrane reactors. Three materials with constant Co/Fe ratio, LaSrCo0.5Fe0.5O4-δ (n = 1), La0.3Sr2.7CoFeO7-δ (n = 2), and LaSr3Co1.5Fe1.5O10-δ (n = 3) were synthesized and studied via in situ neutron powder diffraction between 765 K and 1070 K at a pO2 of 10-1 atm. Then, the structures were fit to a tetragonal I4/mmm space group, and were found to have increased total oxygen vacancy concentration in the order La0.3Sr2.7CoFeO7-δ > LaSr3Co1.5Fe1.5O10-δmore » > LaSrCo0.5Fe0.5O4-δ, following the trend predicted for charge compensation upon increasing Sr2+/La3+ ratio. The oxygen vacancies within the material were almost exclusively located within the perovskite layers for all of the crystal structures with only minimal vacancy formation in the rock-salt layer. Finally, analysis of the concentration of these vacancies at each distinct crystallographic site and the anisotropic atomic displacement parameters for the oxygen sites reveals potential preferred oxygen transport pathways through the perovskite layers.« less

  3. Oxygen transport through polyethylene terephthalate (PET) coated with plasma-polymerized acetylene at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Wemlinger, Erik; Pedrow, Patrick; Garcia-Pérez, Manuel; Sablani, Shyam

    2011-10-01

    Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 μm. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film. Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 μm. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film. E.M. Moser, R. Urech, E. Hack, H. Künzli, E. Müller, Thin

  4. Comparison of automated haematology analysers for detection of apoptotic lymphocytes.

    PubMed

    Taga, K; Sawaya, M; Yoshida, M; Kaneko, M; Okada, M; Taniho, M

    2002-06-01

    Automated haematology analysers can rapidly provide accurate blood cell counts and white blood cell differentials. In this study, we evaluated four different haematology analysers for the detection of apoptotic lymphocytes in peripheral blood: MAXM A/L Retic, H*2, Cell-Dyn 3500 and NE-8000. With the MAXM A/L Retic haematology analyser, the apoptotic lymphocyte cluster appeared below the original lymphocyte cluster on the volume/DF1, and to the right under the original lymphocyte cluster on the volume/DF2 scattergrams. With the H*2 haematology analyser, the apoptotic polymorphonuclear lymphocytes produced a higher lobularity index on the BASO channel. With the Cell-Dyn 3500 haematology analyser, the apoptotic lymphocyte cluster appeared to the right side of the original lymphocyte cluster on the 0D/10D scattergram and to the left side of the polymorphonuclear cluster on the 90D/10D scattergram. With the NE-8000 haematology analyser, the apoptotic lymphocyte cluster was not distinguishable. Thus, apoptotic lymphocytes are readily detected on scattergrams generated by selected haematology analysers. PMID:12067276

  5. Oxygen transport and cardiovascular function at extreme altitude: lessons from Operation Everest II

    NASA Technical Reports Server (NTRS)

    Sutton, J. R.; Reeves, J. T.; Groves, B. M.; Wagner, P. D.; Alexander, J. K.; Hultgren, H. N.; Cymerman, A.; Houston, C. S.

    1992-01-01

    Operation Everest II was designed to examine the physiological responses to gradual decompression simulating an ascent of Mt Everest (8,848 m) to an inspired PO2 of 43 mmHg. The principal studies conducted were cardiovascular, respiratory, muscular-skeletal and metabolic responses to exercise. Eight healthy males aged 21-31 years began the "ascent" and six successfully reached the "summit", where their resting arterial blood gases were PO2 = 30 mmHg and PCO2 = 11 mmHg, pH = 7.56. Their maximal oxygen uptake decreased from 3.98 +/- 0.2 L/min at sea level to 1.17 +/- 0.08 L/min at PIO2 43 mmHg. The principal factors responsible for oxygen transport from the atmosphere to tissues were (1) Alveolar ventilation--a four fold increase. (2) Diffusion from the alveolus to end capillary blood--unchanged. (3) Cardiac function (assessed by hemodynamics, echocardiography and electrocardiography)--normal--although maximum cardiac output and heart rate were reduced. (4) Oxygen extraction--maximal with PvO2 14.8 +/- 1 mmHg. With increasing altitude maximal blood and muscle lactate progressively declined although at any submaximal intensity blood and muscle lactate was higher at higher altitudes.

  6. Phenotype-environment association of the oxygen transport system in trimorphic European whitefish (Coregonus lavaretus) populations.

    PubMed

    Evans, Melissa L; Praebel, Kim; Peruzzi, Stefano; Amundsen, Per-Arne; Bernatchez, Louis

    2014-08-01

    Replicated adaptive radiation events, typified by phenotypic divergence across resource axes, provide important insight into the eco-evolutionary dynamics that lead to the formation of new species. Here, we show that in trimorphic adaptive radiations of European whitefish (Coregonus lavaretus), divergence of the oxygen transport system has occurred across the pelagic/littoral (shallow)-profundal (deep) resource axis, and at multiple biological scales. Profundal whitefish exhibited significantly larger red blood cells (RBCs), a greater proportion of cathodic hemoglobin protein components, and higher hemoglobin transcript abundance in kidney compared to littoral and pelagic morphs. Hemoglobin transcript abundance in brain and gill, but not kidney, and anodic hemoglobin protein component diversity in blood were also linked to variation at an intronic single nucleotide polymorphism (SNP). As the whitefish morphs differ in population genetic structure at this SNP, hemoglobin transcript and protein divergence between profundal and pelagic/littoral morphs is likely being driven by genetic divergence. Our findings, along with our previous work on lake whitefish, highlight the importance of the oxygen transport system to the postglacial colonization of novel lacustrine environments by whitefish throughout the northern hemisphere. PMID:24766154

  7. Oxygen transport properties estimation by classical trajectory-direct simulation Monte Carlo

    NASA Astrophysics Data System (ADS)

    Bruno, Domenico; Frezzotti, Aldo; Ghiroldi, Gian Pietro

    2015-05-01

    Coupling direct simulation Monte Carlo (DSMC) simulations with classical trajectory calculations is a powerful tool to improve predictive capabilities of computational dilute gas dynamics. The considerable increase in computational effort outlined in early applications of the method can be compensated by running simulations on massively parallel computers. In particular, Graphics Processing Unit acceleration has been found quite effective in reducing computing time of classical trajectory (CT)-DSMC simulations. The aim of the present work is to study dilute molecular oxygen flows by modeling binary collisions, in the rigid rotor approximation, through an accurate Potential Energy Surface (PES), obtained by molecular beams scattering. The PES accuracy is assessed by calculating molecular oxygen transport properties by different equilibrium and non-equilibrium CT-DSMC based simulations that provide close values of the transport properties. Comparisons with available experimental data are presented and discussed in the temperature range 300-900 K, where vibrational degrees of freedom are expected to play a limited (but not always negligible) role.

  8. Oxygen transport properties estimation by classical trajectory–direct simulation Monte Carlo

    SciTech Connect

    Bruno, Domenico; Frezzotti, Aldo Ghiroldi, Gian Pietro

    2015-05-15

    Coupling direct simulation Monte Carlo (DSMC) simulations with classical trajectory calculations is a powerful tool to improve predictive capabilities of computational dilute gas dynamics. The considerable increase in computational effort outlined in early applications of the method can be compensated by running simulations on massively parallel computers. In particular, Graphics Processing Unit acceleration has been found quite effective in reducing computing time of classical trajectory (CT)-DSMC simulations. The aim of the present work is to study dilute molecular oxygen flows by modeling binary collisions, in the rigid rotor approximation, through an accurate Potential Energy Surface (PES), obtained by molecular beams scattering. The PES accuracy is assessed by calculating molecular oxygen transport properties by different equilibrium and non-equilibrium CT-DSMC based simulations that provide close values of the transport properties. Comparisons with available experimental data are presented and discussed in the temperature range 300–900 K, where vibrational degrees of freedom are expected to play a limited (but not always negligible) role.

  9. Modeling of ambient-meniscus melt interactions associated with carbon and oxygen transport in EFG of silicon ribbon

    SciTech Connect

    Kalejs, J.P.; Chin, L.Y.

    1982-06-01

    Impurity transport processes associated with interaction of reactive ambient gases and meniscus melt during growth of silicon ribbon by the edge-defined film-fed growth (EFG) technique have been investigated with the help of numerical solution of mass and momentum transport equations. The transport of oxygen and carbon is examined in detail. It is shown that oxygen transport from meniscus sources can account for the interstitial oxygen observed to be introduced into ribbon grown with Co/sub 2/ in the meniscus ambient. Growth speed is the process parameter that has the most pronounced influence on ribbon impurity levels when a source or sink for the impurity is present on the meniscus surface. 14 refs.

  10. Oxygen and carbon dioxide transport in time-dependent blood flow past fiber rectangular arrays

    NASA Astrophysics Data System (ADS)

    Zierenberg, Jennifer R.; Fujioka, Hideki; Hirschl, Ronald B.; Bartlett, Robert H.; Grotberg, James B.

    2009-03-01

    The influence of time-dependent flows on oxygen and carbon dioxide transport for blood flow past fiber arrays arranged in in-line and staggered configurations was computationally investigated as a model for an artificial lung. Both a pulsatile flow, which mimics the flow leaving the right heart and passing through a compliance chamber before entering the artificial lung, and a right ventricular flow, which mimics flow leaving the right heart and directly entering the artificial lung, were considered in addition to a steady flow. The pulsatile flow was modeled as a sinusoidal perturbation superimposed on a steady flow while the right ventricular flow was modeled to accurately depict the period of flow acceleration (increasing flow) and deceleration (decreasing flow) during systole followed by zero flow during diastole. It was observed that the pulsatile flow yielded similar gas transport as compared to the steady flow, while the right ventricular flow resulted in smaller gas transport, with the decrease increasing with Re. The pressure drop across the fiber array (a measure of the resistance), work (an indicator of the work required of the right heart), and shear stress (a measure of potential blood cell activation and damage) are lowest for steady flow, followed by pulsatile flow, and then right ventricular flow. The pressure drop, work, shear stress, and Sherwood numbers (a measure of the gas transport efficiency) decrease with increasing porosity and are smaller for AR <1 as compared to AR >1 (AR is the distance between fibers in the flow direction/distance between fibers in direction perpendicular to flow), although for small porosities the Sherwood numbers are of similar magnitude. In general, for any fiber array geometry, high pressure drop, work, and shear stresses correlate with high Sherwood numbers, and low pressure drop, work, and shear stresses correlate with low Sherwood numbers creating a need for a compromise between pressure drop/work/shear stresses

  11. Haematological cancer and quality of life: a systematic literature review.

    PubMed

    Allart-Vorelli, P; Porro, B; Baguet, F; Michel, A; Cousson-Gélie, F

    2015-01-01

    The aim of this study is to examine the impact of haematological cancers on quality of life (QoL). A review of the international literature was conducted from the databases 'PsycInfo' and 'Medline' using the keywords: 'haematological cancer', 'quality of life', 'physical', 'psychological', 'social', 'vocational', 'professional', 'economic', 'cognitive', and 'sexual'. Twenty-one reliable studies were analysed. Among these studies, 12 showed that haematological cancer altered overall QoL, 8 papers found a deterioration of physical dimension, 8 papers reported on functional and role dimensions, 11 papers reported on the psychological component and 9 on the social component. Moreover, one study and two manuscripts, respectively, reported deteriorated sexual and cognitive dimensions. Our review demonstrates that the different dimensions of QoL are deteriorated by haematological malignancies and, probably, by the side effects of treatment. PMID:25909835

  12. Trial of Haploidentical Stem Cell Transplantation for Haematological Cancers

    ClinicalTrials.gov

    2015-12-07

    Hodgkin's Lymphoma; Non-Hodgkin's Lymphoma; Acute Myeloid Leukaemia; Acute Lymphoblastic Leukaemia; Myelodysplastic Syndrome; Chronic Myeloid Leukaemia; Chronic Lymphocytic Leukaemia; Acquired Bone Marrow Failure Syndromes; Other Haematological Malignancies; Unrelated HSCT Indicated

  13. Haematological cancer and quality of life: a systematic literature review

    PubMed Central

    Allart-Vorelli, P; Porro, B; Baguet, F; Michel, A; Cousson-Gélie, F

    2015-01-01

    The aim of this study is to examine the impact of haematological cancers on quality of life (QoL). A review of the international literature was conducted from the databases ‘PsycInfo' and 'Medline' using the keywords: 'haematological cancer', 'quality of life', 'physical', 'psychological', 'social', 'vocational', 'professional', 'economic', 'cognitive', and 'sexual'. Twenty-one reliable studies were analysed. Among these studies, 12 showed that haematological cancer altered overall QoL, 8 papers found a deterioration of physical dimension, 8 papers reported on functional and role dimensions, 11 papers reported on the psychological component and 9 on the social component. Moreover, one study and two manuscripts, respectively, reported deteriorated sexual and cognitive dimensions. Our review demonstrates that the different dimensions of QoL are deteriorated by haematological malignancies and, probably, by the side effects of treatment. PMID:25909835

  14. Oxygen transport pathways in Ruddlesden–Popper structured oxides revealed via in situ neutron diffraction

    SciTech Connect

    Tomkiewicz, Alex C.; Tamimi, Mazin; Huq, Ashfia; McIntosh, Steven

    2015-09-21

    Ruddlesden-Popper structured oxides, general form An+1BnO3n+1, consist of n-layers of the perovskite structure stacked in between rock-salt layers, and have potential application in solid oxide electrochemical cells and ion transport membrane reactors. Three materials with constant Co/Fe ratio, LaSrCo0.5Fe0.5O4-δ (n = 1), La0.3Sr2.7CoFeO7-δ (n = 2), and LaSr3Co1.5Fe1.5O10-δ (n = 3) were synthesized and studied via in situ neutron powder diffraction between 765 K and 1070 K at a pO2 of 10-1 atm. Then, the structures were fit to a tetragonal I4/mmm space group, and were found to have increased total oxygen vacancy concentration in the order La0.3Sr2.7CoFeO7-δ > LaSr3Co1.5Fe1.5O10-δ > LaSrCo0.5Fe0.5O4-δ, following the trend predicted for charge compensation upon increasing Sr2+/La3+ ratio. The oxygen vacancies within the material were almost exclusively located within the perovskite layers for all of the crystal structures with only minimal vacancy formation in the rock-salt layer. Finally, analysis of the concentration of these vacancies at each distinct crystallographic site and the anisotropic atomic displacement parameters for the oxygen sites reveals potential preferred oxygen transport pathways through the perovskite layers.

  15. First experience with the ultra compact mobile extracorporeal membrane oxygenation system Cardiohelp in interhospital transport.

    PubMed

    Philipp, Alois; Arlt, Matthias; Amann, Matthias; Lunz, Dirk; Müller, Thomas; Hilker, Michael; Graf, Bernhard; Schmid, Christof

    2011-06-01

    In patients with severe cardiopulmonary failure extracorporeal assist devices are to support patients during resuscitation, for transportation, until organ recovery, and as bridge to further therapeutic modalities. We report on our first experience with the new Cardiohelp system for interhospital transfer of cardiopulmonarily compromised patients. The Cardiohelp system was used for transportation and in-house treatment in six male patients with a mean age of 41±17 years. Five patients suffered respiratory failure; one patient with acute myocardial infarction was in profound cardiogenic shock. Accordingly, the Cardiohelp system was implanted as a venovenous extracorporeal membrane oxygenation (ECMO) in five patients and as a venoarterial system in one patient. The preECMO ventilation time was 0.5-4 days. The patients were transported to our institution by car (n=1) or helicopter (n=5) over a distance of 80-5850 km. The subsequent in-house ECMO support was continued with the Cardiohelp and lasted for 5-13 days. PostECMO ventilation was one to 25 days. A 100% survival was achieved. The portable Cardiohelp system allows location-independent stabilization of cardiopulmonary compromised patients with consecutive interhospital transfer and in-house treatment. The integrated sensors, which register arterial and venous line pressure, blood temperature, hemoglobin as well as SvO(2), greatly alleviate its management and considerably increase safety. PMID:21388980

  16. Constraining Data Mining with Physical Models: Voltage- and Oxygen Pressure-Dependent Transport in Multiferroic Nanostructures

    DOE PAGESBeta

    Strelcov, Evgheni; Belianinov, Alexei; Hsieh, Ying-Hui; Chu, Ying-Hao; Kalinin, Sergei V.

    2015-08-27

    Development of new generation electronic devices requires understanding and controlling the electronic transport in ferroic, magnetic, and optical materials, which is hampered by two factors. First, the complications of working at the nanoscale, where interfaces, grain boundaries, defects, and so forth, dictate the macroscopic characteristics. Second, the convolution of the response signals stemming from the fact that several physical processes may be activated simultaneously. Here, we present a method of solving these challenges via a combination of atomic force microscopy and data mining analysis techniques. Rational selection of the latter allows application of physical constraints and enables direct interpretation ofmore » the statistically significant behaviors in the framework of the chosen physical model, thus distilling physical meaning out of raw data. We demonstrate our approach with an example of deconvolution of complex transport behavior in a bismuth ferrite–cobalt ferrite nanocomposite in ambient and ultrahigh vacuum environments. Measured signal is apportioned into four electronic transport patterns, showing different dependence on partial oxygen and water vapor pressure. These patterns are described in terms of Ohmic conductance and Schottky emission models in the light of surface electrochemistry. Finally and furthermore, deep data analysis allows extraction of local dopant concentrations and barrier heights empowering our understanding of the underlying dynamic mechanisms of resistive switching.« less

  17. Constraining Data Mining with Physical Models: Voltage- and Oxygen Pressure-Dependent Transport in Multiferroic Nanostructures

    SciTech Connect

    Strelcov, Evgheni; Belianinov, Alexei; Hsieh, Ying-Hui; Chu, Ying-Hao; Kalinin, Sergei V.

    2015-08-27

    Development of new generation electronic devices requires understanding and controlling the electronic transport in ferroic, magnetic, and optical materials, which is hampered by two factors. First, the complications of working at the nanoscale, where interfaces, grain boundaries, defects, and so forth, dictate the macroscopic characteristics. Second, the convolution of the response signals stemming from the fact that several physical processes may be activated simultaneously. Here, we present a method of solving these challenges via a combination of atomic force microscopy and data mining analysis techniques. Rational selection of the latter allows application of physical constraints and enables direct interpretation of the statistically significant behaviors in the framework of the chosen physical model, thus distilling physical meaning out of raw data. We demonstrate our approach with an example of deconvolution of complex transport behavior in a bismuth ferrite–cobalt ferrite nanocomposite in ambient and ultrahigh vacuum environments. Measured signal is apportioned into four electronic transport patterns, showing different dependence on partial oxygen and water vapor pressure. These patterns are described in terms of Ohmic conductance and Schottky emission models in the light of surface electrochemistry. Finally and furthermore, deep data analysis allows extraction of local dopant concentrations and barrier heights empowering our understanding of the underlying dynamic mechanisms of resistive switching.

  18. Constraining Data Mining with Physical Models: Voltage- and Oxygen Pressure-Dependent Transport in Multiferroic Nanostructures.

    PubMed

    Strelcov, Evgheni; Belianinov, Alexei; Hsieh, Ying-Hui; Chu, Ying-Hao; Kalinin, Sergei V

    2015-10-14

    Development of new generation electronic devices necessitates understanding and controlling the electronic transport in ferroic, magnetic, and optical materials, which is hampered by two factors. First, the complications of working at the nanoscale, where interfaces, grain boundaries, defects, and so forth, dictate the macroscopic characteristics. Second, the convolution of the response signals stemming from the fact that several physical processes may be activated simultaneously. Here, we present a method of solving these challenges via a combination of atomic force microscopy and data mining analysis techniques. Rational selection of the latter allows application of physical constraints and enables direct interpretation of the statistically significant behaviors in the framework of the chosen physical model, thus distilling physical meaning out of raw data. We demonstrate our approach with an example of deconvolution of complex transport behavior in a bismuth ferrite-cobalt ferrite nanocomposite in ambient and ultrahigh vacuum environments. Measured signal is apportioned into four electronic transport patterns, showing different dependence on partial oxygen and water vapor pressure. These patterns are described in terms of Ohmic conductance and Schottky emission models in the light of surface electrochemistry. Furthermore, deep data analysis allows extraction of local dopant concentrations and barrier heights empowering our understanding of the underlying dynamic mechanisms of resistive switching. PMID:26312554

  19. Effects of deviations from stoichiometry, oxygen excess and substitution of Cr for Fe on the chemical transport of hematite with TeCl 4 as a transporting agent

    NASA Astrophysics Data System (ADS)

    Peshev, P.; Toshev, A.; Krabbes, G.; Gerlach, U.; Opperman, H.

    1984-02-01

    Single crystals of pure hematite (α-Fe 2O 3) and hematite in which the iron is partially replaced by chromium (Fe 2- yCr yO 3) can be obtained by chemical transport using TeCl 4 as a transporting agent. A thermodynamic analysis has shown the transport to be substantially affected by some additional conditions such as slight deviations from stoichiometry and small amounts of excess oxygen and dopants. The transport of pure, practically stoichiometric hematite occurs at temperatures above 900°C in the direction from the hot to the cold zone. At pressures below 1 MPa and temperatures ranging from 750 to 900°C (which correspond to about 12 mg/ml TeCl 4), the transport proceeds in the opposite direction. However, in a similar temperature range, the transport reaction proceeds in the direction hot → cold again, on introducing small excess oxygen amounts into the ampoule and in cases when the hematite shows some oxygen deficiency. From a mixture of Fe 2O 3/Fe 3O 4, the hematite is transferred to the cold zone. Chromium-containing hematite is also transported to the cold zone. The composition of the mixed Fe 2- yCr yO 3 crystals obtained is different from that of the initial substance. All results of the thermodynamic analysis were confirmed by experiments.

  20. KRW oxygen-blown gasification combined cycle: Carbon dioxide recovery, transport, and disposal

    SciTech Connect

    Doctor, R.D.; Molburg, J.C.; Thimmapuram, P.R.

    1996-08-01

    This project emphasizes CO{sub 2}-capture technologies combined with integrated gasification combined-cycle (IGCC) power systems. Complementary evaluations address CO{sub 2} transportation, CO{sub 2} use, and options for the long-term sequestration of unused CO{sub 2}. The intent is to provide the CO{sub 2} budget, or an equivalent CO{sub 2} budget, associated with each of the individual energy-cycle steps, in addition to process design capital and operating costs. The base case is a 458-MW (gross generation) IGCC system that uses an oxygen-blown Kellogg-Rust-Westinghouse agglomerating fluidized-bed gasifier, Illinois No. 6 bituminous coal feed, and low-pressure glycol sulfur removal followed by Claus/SCOT treatment to produce a saleable product. Mining, feed preparation, and conversion result in a net electric power production for the entire energy cycle of 411 MW, with a CO{sub 2} release rate of 0.801 kg/k Whe. For comparison, in two cases, the gasifier output was taken through water-gas shift and then to low-pressure glycol H{sub 2}S recovery, followed by either low-pressure glycol or membrane CO{sub 2} recovery and then by a combustion turbine being fed a high-hydrogen-content fuel. Two additional cases employed chilled methanol for H{sub 2}S recovery and a fuel cell as the topping cycle with no shift stages. From the IGCC plant, a 500-km pipeline took the CO{sub 2} to geological sequestering. In a comparison of air-blown and oxygen-blown CO{sub 2}-release base cases, the cost of electricity for the air-blown IGCC was 56.86 mills/kWh, and the cost of oxygen-blown IGCC was 58.29 mills/kWh.

  1. Basic Regulatory Principles of Escherichia coli's Electron Transport Chain for Varying Oxygen Conditions

    PubMed Central

    Henkel, Sebastian G.; Beek, Alexander Ter; Steinsiek, Sonja; Stagge, Stefan; Bettenbrock, Katja; de Mattos, M. Joost Teixeira; Sauter, Thomas; Sawodny, Oliver; Ederer, Michael

    2014-01-01

    For adaptation between anaerobic, micro-aerobic and aerobic conditions Escherichia coli's metabolism and in particular its electron transport chain (ETC) is highly regulated. Although it is known that the global transcriptional regulators FNR and ArcA are involved in oxygen response it is unclear how they interplay in the regulation of ETC enzymes under micro-aerobic chemostat conditions. Also, there are diverse results which and how quinones (oxidised/reduced, ubiquinone/other quinones) are controlling the ArcBA two-component system. In the following a mathematical model of the E. coli ETC linked to basic modules for substrate uptake, fermentation product excretion and biomass formation is introduced. The kinetic modelling focusses on regulatory principles of the ETC for varying oxygen conditions in glucose-limited continuous cultures. The model is based on the balance of electron donation (glucose) and acceptance (oxygen or other acceptors). Also, it is able to account for different chemostat conditions due to changed substrate concentrations and dilution rates. The parameter identification process is divided into an estimation and a validation step based on previously published and new experimental data. The model shows that experimentally observed, qualitatively different behaviour of the ubiquinone redox state and the ArcA activity profile in the micro-aerobic range for different experimental conditions can emerge from a single network structure. The network structure features a strong feed-forward effect from the FNR regulatory system to the ArcBA regulatory system via a common control of the dehydrogenases of the ETC. The model supports the hypothesis that ubiquinone but not ubiquinol plays a key role in determining the activity of ArcBA in a glucose-limited chemostat at micro-aerobic conditions. PMID:25268772

  2. Regulation of nitrite transport in red blood cells by hemoglobin oxygen fractional saturation.

    PubMed

    Vitturi, Dario A; Teng, Xinjun; Toledo, José C; Matalon, Sadis; Lancaster, Jack R; Patel, Rakesh P

    2009-05-01

    Allosteric regulation of nitrite reduction by deoxyhemoglobin has been proposed to mediate nitric oxide (NO) formation during hypoxia. Nitrite is predominantly an anion at physiological pH, raising questions about the mechanism by which it enters the red blood cell (RBC) and whether this is regulated and coupled to deoxyhemoglobin-mediated reduction. We tested the hypothesis that nitrite transport by RBCs is regulated by fractional saturation. Using human RBCs, nitrite consumption was faster at lower fractional saturations, consistent with faster reactions with deoxyheme. A membrane-based regulation was suggested by slower nitrite consumption with intact versus lysed RBCs. Interestingly, upon nitrite addition, intracellular nitrite concentrations attained a steady state that, despite increased rates of consumption, did not change with decreasing oxygen tensions, suggesting a deoxygenation-sensitive step that either increases nitrite import or decreases the rate of nitrite export. A role for anion exchanger (AE)-1 in the control of nitrite export was suggested by increased intracellular nitrite concentrations in RBCs treated with DIDS. Moreover, deoxygenation decreased steady-state levels of intracellular nitrite in AE-1-inhibited RBCs. Based on these data, we propose a model in which deoxyhemoglobin binding to AE-1 inhibits nitrite export under low oxygen tensions allowing for the coupling between deoxygenation and nitrite reduction to NO along the arterial-to-venous gradient. PMID:19286940

  3. ZERO EMISSION POWER PLANTS USING SOLID OXIDE FUEL CELLS AND OXYGEN TRANSPORT MEMBRANES

    SciTech Connect

    G. Maxwell Christie; Troy M. Raybold

    2003-06-10

    Over 16,700 hours of operational experience was gained for the Oxygen Transport Membrane (OTM) elements of the proposed SOFC/OTM zero-emission power generation concept. It was repeatedly demonstrated that OTMs with no additional oxidation catalysts were able to completely oxidize the remaining depleted fuel in a simulated SOFC anode exhaust at an O{sub 2} flux that met initial targets. In such cases, neither residual CO nor H{sub 2} were detected to the limits of the gas chromatograph (<10 ppm). Dried OTM afterburner exhaust streams contained up to 99.5% CO{sub 2}. Oxygen flux through modified OTMs was double or even triple that of the standard OTMs used for the majority of testing purposes. Both the standard and modified membranes in laboratory-scale and demonstration-sized formats exhibited stable performance over extended periods (2300 to 3500 hours or 3 to 5 months). Reactor contaminants, were determined to negatively impact OTM performance stability. A method of preventing OTM performance degradation was developed and proven to be effective. Information concerning OTM and seal reliability over extended periods and through various chemical and thermal shocks and cycles was also obtained. These findings were used to develop several conceptual designs for pilot (10 kWe) and commercial-scale (250 kWe) SOFC/OTM zero emission power generation systems.

  4. Effect on Oxygen Cost of Transport from 8-Weeks of Progressive Training with Barefoot Running.

    PubMed

    Tam, N; Tucker, R; Astephen Wilson, J L; Santos-Concejero, J

    2015-11-01

    Popular interest in barefoot running has emerged as a result of its alleged performance and injury prevention benefits. Oxygen cost of transport (COT) improvements from barefoot running, however, remains equivocal. The aim of this study was to determine the influence of an 8-week progressive barefoot training program on COT and associated spatiotemporal variables. 15 male runners participated in this study. Variables such as oxygen uptake, biomechanical and spatiotemporal characteristics of gait, including ground contact (GC) and swing time; stride length and frequency and ankle plantar-dorsiflexion were measured pre- and post-intervention. The COT did not differ between barefoot and shod running either pre- or post-training. Improved barefoot COT (p<0.05) but not shod was found between pre- and post-training. Biomechanical differences between barefoot and shod conditions persisted over the training period. A decrease in barefoot COT was associated with a decrease in GC time (p=0.003, r=0.688) and a small increase in stride frequency (p=0.030; r=0.569). Ground contact time and stride frequency, previously associated with COT, only partly contribute (32% - Stride frequency and 47% - GC time) to a decrease in COT after barefoot training. Thus other physiological and biomechanical variables must influence the improvement in COT after a barefoot training intervention. PMID:26332902

  5. Optical imaging measurements of oxygen transport fluctuations and gradients in tumor microvascular networks

    NASA Astrophysics Data System (ADS)

    Sorg, Brian S.; Hardee, Matthew E.; Moeller, Benjamin J.; Dewhirst, Mark W.

    2006-02-01

    It is well established that hypoxia can influence tumor biology and physiology, gene expression, metastatic potential, treatment efficacy, and patient survival. Most human solid tumors have been shown to have some hypoxic regions, thus there is a strong motivation to understand the various causes of hypoxia. One key to understanding tumor hypoxia involves the study of oxygen transport to tumors, and the connection between hypoxia, tumor microvasculature, and the tumor microenvironment. Recent research has suggested that the causes of tumor hypoxia are much more complex than indicated by the classical paradigms ("chronic" and "acute" hypoxia), and several potential factors have been identified. Two such factors are temporal fluctuations in tissue pO II and longitudinal gradients in oxygen transport. Research has shown the existence of low frequency (<2 cycles per minute) fluctuations in tumor pO II without cessation of blood flow that can lead to transient hypoxia. In addition, longitudinal gradients in tumor pO II along the arteriolar afferent direction have been documented in window chamber tumors. However, the causes of the pO II temporal fluctuations and longitudinal gradients are not exactly known, and the clinical significance of these observations is not well understood. In this preliminary study, we demonstrate the potential of optical imaging measurements of hemoglobin saturation to add new information in these areas. Slow temporal fluctuations of hemoglobin saturation (HbSat) and gradients in the average HbSat were observed in some 4T1 mouse mammary carcinoma microvessels. With additional research, the mechanisms behind these phenomena and insights into their clinical significance may be revealed.

  6. Oxygen adsorption and electronic transport properties of Fe-substituted YBaCo{sub 4}O{sub 7} compounds

    SciTech Connect

    Hao, Haoshan; He, Qinglin; Cheng, Yongguang; Zhao, Limin

    2014-05-01

    Graphical abstract: - Highlights: • The conduction mechanism of YBaCo{sub 4}O{sub 7} system was established. • The effect of Fe substitution on the electronic transport was discussed. • The effect of oxygen adsorption/desorption processes on the transport properties was investigated. - Abstract: YBaCo{sub 4−x}Fe{sub x}O{sub 7} (0.0 ≤ x ≤ 0.8) samples were prepared by the solid-state reaction method and the effect of Fe substitution and oxygen adsorption/desorption on the electronic transport properties was investigated from room temperature to 900 °C. Fe for Co substitution results in a slight decline in the oxygen storage capacity at lower temperature (200–400 °C) and an increase of the phase-decomposition temperature at higher temperature (700–900 °C). Both the hole concentration and mobility are reduced in the Fe-containing compositions. Electrical resistivity, Seebeck coefficient, and conduction activation energy increase with the increasing Fe content. A close correlativity between oxygen adsorption and electronic transport behavior was observed in YBaCo{sub 4−x}Fe{sub x}O{sub 7} system. Oxygen adsorption decreases the electrical resistivity and Seebeck coefficients because of the increase of hole concentration at lower temperature and the phase decomposition at higher temperature.

  7. Zero Emission Power Plants Using Solid Oxide Fuel Cells and Oxygen Transport Membranes

    SciTech Connect

    Shockling, Larry A.; Huang, Keqin; Gilboy, Thomas E.; Christie, G. Maxwell; Raybold, Troy M.

    2001-11-06

    Siemens Westinghouse Power Corp. (SWPC) is engaged in the development of Solid Oxide Fuel Cell stationary power systems. SWPC has combined DOE Developmental funds with commercial customer funding to establish a record of successful SOFC field demonstration power systems of increasing size. SWPC will soon deploy the first unit of a newly developed 250 kWe Combined Heat Power System. It will generate electrical power at greater than 45% electrical efficiency. The SWPC SOFC power systems are equipped to operate on lower number hydrocarbon fuels such as pipeline natural gas, which is desulfurized within the SOFC power system. Because the system operates with a relatively high electrical efficiency, the CO2 emissions, {approx}1.0 lb CO2/ kW-hr, are low. Within the SOFC module the desulfurized fuel is utilized electrochemically and oxidized below the temperature for NOx generation. Therefore the NOx and SOx emissions for the SOFC power generation system are near negligible. The byproducts of the power generation from hydrocarbon fuels that are released into the environment are CO2 and water vapor. This forward looking DOE sponsored Vision 21 program is supporting the development of methods to capture and sequester the CO2, resulting in a Zero Emission power generation system. To accomplish this, SWPC is developing a SOFC module design, to be demonstrated in operating hardware, that will maintain separation of the fuel cell anode gas, consisting of H2, CO, H2O and CO2, from the vitiated air. That anode gas, the depleted fuel stream, containing less than 18% (H2 + CO), will be directed to an Oxygen Transport Membrane (OTM) Afterburner that is being developed by Praxair, Inc.. The OTM is supplied air and the depleted fuel. The OTM will selectively transport oxygen across the membrane to oxidize the remaining H2 and CO. The water vapor is then condensed from the totally 1.5.DOC oxidized fuel stream exiting the afterburner, leaving only the CO2 in gaseous form. That CO2 can

  8. Unprecedented Perovskite Oxyfluoride Membranes with High-Efficiency Oxygen Ion Transport Paths for Low-Temperature Oxygen Permeation.

    PubMed

    Zhu, Jiawei; Liu, Gongping; Liu, Zhengkun; Chu, Zhenyu; Jin, Wanqin; Xu, Nanping

    2016-05-01

    Unprecedented perovskite oxyfluoride membranes, a new generation of mixed ionic-electronic conducting (MIEC) membranes, feature extraordinary performance for low-temperature oxygen permeation, which transcend the performance of state-of-the-art MIEC membranes and fulfil commercial requirements. These results provide important progress for MIEC membranes and will potentially open the door to exploring high-performance MIEC compounds. PMID:26970399

  9. Simulating unsteady transport of nitrogen, biochemical oxygen demand, and dissolved oxygen in the Chattahoochee River downstream from Atlanta, Georgia

    USGS Publications Warehouse

    Jobson, Harvey E.

    1985-01-01

    As part of an intensive water-quality assessment of the Chattahoochee River, repetitive water-quality measurements were made at 12 sites along a 69-kilometer reach of the river downstream of Atlanta, Georgia. Concentrations of seven constituents (temperature, dissolved oxygen, ultimate carbonaceous biochemical oxygen demand (BOD), organic nitrogen, ammonia, nitrite, and nitrate) were obtained during two periods of 36 hours, one starting on August 30, 1976, and the other starting on May 31, 1977. The study reach contains one large and several small sewage outfalls and receives the cooling water from two large powerplants. An unsteady water-quality model of the Lagrangian type was calibrated using the 1977 data and verified using the 1976 data. The model provided a good means of interpreting these data even though both the flow and the pollution loading rates were highly unsteady. A kinetic model of the cascade type accurately described the physical and biochemical processes occurring in the river. All rate coefficients, except reaeration coefficients and those describing the resuspension of BOD, were fitted to the 1977 data and verified using the 1976 data. The study showed that, at steady low flow, about 38 percent of the BOD settled without exerting an oxygen demand. At high flow, this settled BOD was resuspended and exerted an immediate oxygen demand. About 70 percent of the ammonia extracted from the water column was converted to nitrite, but the fate of the remaining 30 percent is unknown. Photosynthetic production was not an important factor in the oxygen balance during either run.

  10. Predicted consequences of diabetes and SGLT inhibition on transport and oxygen consumption along a rat nephron.

    PubMed

    Layton, Anita T; Vallon, Volker; Edwards, Aurélie

    2016-06-01

    Diabetes increases the reabsorption of Na(+) (TNa) and glucose via the sodium-glucose cotransporter SGLT2 in the early proximal tubule (S1-S2 segments) of the renal cortex. SGLT2 inhibitors enhance glucose excretion and lower hyperglycemia in diabetes. We aimed to investigate how diabetes and SGLT2 inhibition affect TNa and sodium transport-dependent oxygen consumption [Formula: see text] along the whole nephron. To do so, we developed a mathematical model of water and solute transport from the Bowman space to the papillary tip of a superficial nephron of the rat kidney. Model simulations indicate that, in the nondiabetic kidney, acute and chronic SGLT2 inhibition enhances active TNa in all nephron segments, thereby raising [Formula: see text] by 5-12% in the cortex and medulla. Diabetes increases overall TNa and [Formula: see text] by ∼50 and 100%, mainly because it enhances glomerular filtration rate (GFR) and transport load. In diabetes, acute and chronic SGLT2 inhibition lowers [Formula: see text] in the cortex by ∼30%, due to GFR reduction that lowers proximal tubule active TNa, but raises [Formula: see text] in the medulla by ∼7%. In the medulla specifically, chronic SGLT2 inhibition is predicted to increase [Formula: see text] by 26% in late proximal tubules (S3 segments), by 2% in medullary thick ascending limbs (mTAL), and by 9 and 21% in outer and inner medullary collecting ducts (OMCD and IMCD), respectively. Additional blockade of SGLT1 in S3 segments enhances glucose excretion, reduces [Formula: see text] by 33% in S3 segments, and raises [Formula: see text] by <1% in mTAL, OMCD, and IMCD. In summary, the model predicts that SGLT2 blockade in diabetes lowers cortical [Formula: see text] and raises medullary [Formula: see text], particularly in S3 segments. PMID:26764207

  11. Haematological toxicity of drugs used in psychiatry.

    PubMed

    Flanagan, Robert J; Dunk, Louisa

    2008-01-01

    Almost all classes of psychotropic agents have been reported to cause blood dyscrasias. Mechanisms include direct toxic effects upon the bone marrow, the formation of antibodies against haematopoietic precursors or involve peripheral destruction of cells. Agranulocytosis is probably the most important drug-related blood dyscrasia. The mortality from drug-induced agranulocytosis is 5-10% in Western countries. The manifestations of agranulocytosis are secondary to infection. Aggressive treatment with intravenous broad-spectrum antimicrobials and bone marrow stimulants may be required. Of drugs encountered in psychiatry, antipsychotics including clozapine (risk of agranulocytosis approximately 0.8%, predominantly in the first year of treatment) and phenothiazines (chlorpromazine agranulocytosis risk approximately 0.13%), and antiepileptics (notably carbamazepine, neutropenia risk approximately 0.5%) are the most common causes of drug-related neutropenia/agranulocytosis. Drugs known to cause neutropenia should not be used concomitantly with other drugs known to cause this problem. High temperature and other indicators of possible infection should be looked for routinely during treatment. Clozapine is well known as a drug that can cause blood dyscrasias, but olanzapine and other atypicals may also cause similar problems. In addition to genetic factors, there are likely to be dose-related and immunological components to these phenomena. Important lessons have been learnt from the haematological monitoring that is necessary with clozapine and the monitoring has been very successful in preventing deaths related to clozapine-induced agranulocytosis. Continuing research into the mechanisms of drug-induced neutropenia and agranulocytosis may serve to further enhance the safe use not only of clozapine, but also of other agents. PMID:18098216

  12. Zygomycosis in Immunocompromised non-Haematological Patients

    PubMed Central

    Petrikkos, George; Drogari-Apiranthitou, Miranda

    2011-01-01

    Zygomycoses caused by fungi of the mucorales order (mucormycoses) are emerging fungal diseases with a high fatality rate. The most important risk factors include neutropenia or functional neutropenia, diabetic ketoacidosis, iron overload, major trauma, prolonged use of corticosteroids, illicit intravenous drug (ID) use, neonatal prematurity, malnourishment, and maybe a previous exposure to antifungal agents with no activity against zygomycetes, such as voriconazole and echinocandins. A high index of suspicion is crucial for the diagnosis, as prompt and appropriate management can considerably reduce morbidity and mortality. Suspicion index can be increased through recognition of the differential patterns of clinical presentation. In the non- haematological immunocompromised patients, mucormycosis can manifest in various clinical forms, depending on the underlying condition: mostly as rhino-orbital or rhino-cerebral in diabetes patients, pulmonary infection in patients with malignancy or solid organ transplantation, disseminated infection in iron overloaded or deferoxamine treated patients, cerebral - with no sinus involvement - in ID users, gastrointestinal in premature infants or malnourishment, and cutaneous after direct inoculation in immunocompetent individuals with trauma or burns. Treating a patient’s underlying medical condition and reducing immunosuppression are essential to therapy. Rapid correction of metabolic abnormalities is mandatory in cases such as uncontrolled diabetes, and corticosteroids or other immunosuppressive drugs should be discontinued where feasible. AmphotericinB or its newer and less toxic lipid formulations are the drugs of choice regarding antifungal chemotherapy, while extensive surgical debridement is essential to reduce infected and necrotic tissue. A high number of cases could be prevented through measures including diabetes control programmes and proper pre- and post-surgical hygiene. PMID:21625316

  13. Stem hypertrophic lenticels and secondary aerenchyma enable oxygen transport to roots of soybean in flooded soil

    PubMed Central

    Shimamura, Satoshi; Yamamoto, Ryo; Nakamura, Takuji; Shimada, Shinji; Komatsu, Setsuko

    2010-01-01

    Background and Aims Aerenchyma provides a low-resistance O2 transport pathway that enhances plant survival during soil flooding. When in flooded soil, soybean produces aerenchyma and hypertrophic stem lenticels. The aims of this study were to investigate O2 dynamics in stem aerenchyma and evaluate O2 supply via stem lenticels to the roots of soybean during soil flooding. Methods Oxygen dynamics in aerenchymatous stems were investigated using Clark-type O2 microelectrodes, and O2 transport to roots was evaluated using stable-isotope 18O2 as a tracer, for plants with shoots in air and roots in flooded sand or soil. Short-term experiments also assessed venting of CO2 via the stem lenticels. Key Results The radial distribution of the O2 partial pressure (pO2) was stable at 17 kPa in the stem aerenchyma 15 mm below the water level, but rapidly declined to 8 kPa at 200–300 µm inside the stele. Complete submergence of the hypertrophic lenticels at the stem base, with the remainder of the shoot still in air, resulted in gradual declines in pO2 in stem aerenchyma from 17·5 to 7·6 kPa at 13 mm below the water level, and from 14·7 to 6·1 kPa at 51 mm below the water level. Subsequently, re-exposure of the lenticels to air caused pO2 to increase again to 14–17 kPa at both positions within 10 min. After introducing 18O2 gas via the stem lenticels, significant 18O2 enrichment in water extracted from roots after 3 h was confirmed, suggesting that transported O2 sustained root respiration. In contrast, slight 18O2 enrichment was detected 3 h after treatment of stems that lacked aerenchyma and lenticels. Moreover, aerenchyma accelerated venting of CO2 from submerged tissues to the atmosphere. Conclusions Hypertrophic lenticels on the stem of soybean, just above the water surface, are entry points for O2, and these connect to aerenchyma and enable O2 transport into roots in flooded soil. Stems that develop aerenchyma thus serve as a ‘snorkel’ that enables O2 movement

  14. The Effects of Amiloride and Age on Oxygen Consumption Coupled to Electrogenic Sodium Transport in the Human Sigmoid Colon

    PubMed Central

    Carra, Graciela E.; Matus, Daniel; Ibáñez, Jorge E.; Saraví, Fernando D.

    2015-01-01

    Background/Aim: Aerobic metabolism is necessary for ion transport in many transporting epithelia, including the human colonic epithelium. We assessed the effects of the epithelial sodium channel blocker, amiloride, on oxygen consumption and short-circuit current of the human sigmoid epithelium to determine whether these effects were influenced by the age of the subject. Materials and Methods: Segments of the sigmoid colon were obtained from the safety margin of resections performed in patients of 62–77 years of age. Isolated mucosa preparations were obtained and mounted in airtight Ussing chambers, fit for simultaneous measurement of short-circuit current and oxygen concentration, before and after blocking epithelial sodium channels with amiloride (0.1 mmol/L). Regression analyses were performed to assess the associations between short-circuit current, oxygen consumption, and age of the subject as well as to define the relationship between the decreases in short-circuit current and oxygen consumption after blockade. Results: Epithelial sodium channel blockade caused an 80% reduction in short-circuit current and a 26% reduction in oxygen consumption. Regression analysis indicated that both changes were significantly related (r = 0.884; P = 0.0007). Oxygen consumption decreased by 1 μmol/h/cm2 for each 25 μA/cm2 decrease in short-circuit current. Neither short-circuit current nor oxygen consumption had any significant relationship with the age of the subjects. Conclusion: The decrease in epithelial oxygen consumption caused by amiloride is proportional to the decrease in short-circuit current and independent of the age of the subject. PMID:26458855

  15. Muscle oxygen transport and utilization in heart failure: implications for exercise (in)tolerance

    PubMed Central

    Hirai, Daniel M.; Copp, Steven W.; Musch, Timothy I.

    2012-01-01

    The defining characteristic of chronic heart failure (CHF) is an exercise intolerance that is inextricably linked to structural and functional aberrations in the O2 transport pathway. CHF reduces muscle O2 supply while simultaneously increasing O2 demands. CHF severity varies from moderate to severe and is assessed commonly in terms of the maximum O2 uptake, which relates closely to patient morbidity and mortality in CHF and forms the basis for Weber and colleagues' (167) classifications of heart failure, speed of the O2 uptake kinetics following exercise onset and during recovery, and the capacity to perform submaximal exercise. As the heart fails, cardiovascular regulation shifts from controlling cardiac output as a means for supplying the oxidative energetic needs of exercising skeletal muscle and other organs to preventing catastrophic swings in blood pressure. This shift is mediated by a complex array of events that include altered reflex and humoral control of the circulation, required to prevent the skeletal muscle “sleeping giant” from outstripping the pathologically limited cardiac output and secondarily impacts lung (and respiratory muscle), vascular, and locomotory muscle function. Recently, interest has also focused on the dysregulation of inflammatory mediators including tumor necrosis factor-α and interleukin-1β as well as reactive oxygen species as mediators of systemic and muscle dysfunction. This brief review focuses on skeletal muscle to address the mechanistic bases for the reduced maximum O2 uptake, slowed O2 uptake kinetics, and exercise intolerance in CHF. Experimental evidence in humans and animal models of CHF unveils the microvascular cause(s) and consequences of the O2 supply (decreased)/O2 demand (increased) imbalance emblematic of CHF. Therapeutic strategies to improve muscle microvascular and oxidative function (e.g., exercise training and anti-inflammatory, antioxidant strategies, in particular) and hence patient exercise

  16. On the effect of serum on the transport of reactive oxygen species across phospholipid membranes.

    PubMed

    Szili, Endre J; Hong, Sung-Ha; Short, Robert D

    2015-01-01

    The transport of plasma generated reactive oxygen species (ROS) across a simple phospholipid membrane mimic of a (real) cell was investigated. Experiments were performed in cell culture media (Dulbecco's modified Eagle's medium, DMEM), with and without 10% serum. A (broad spectrum) ROS reporter dye, 2,7-dichlorodihydrofluorescein (DCFH), was used to detect the generation of ROS by a helium (He) plasma jet in DMEM using free DCFH and with DCFH encapsulated inside phospholipid membrane vesicles dispersed in DMEM. The authors focus on the concentration and on the relative rates (arbitrary units) for oxidation of DCFH [or the appearance of the oxidized product 2,7-dichlorofluorescein (DCF)] both in solution and within vesicles. In the first 1 h following plasma exposure, the concentration of free DCF in DMEM was ~15× greater in the presence of serum (cf. to the serum-free DMEM control). The DCF in vesicles was ~2× greater in DMEM containing serum compared to the serum-free DMEM control. These data show that serum enhances plasma ROS generation in DMEM. As expected, the role of the phospholipid membrane was to reduce the rate of oxidation of the encapsulated DCFH (with and without serum). And the efficiency of ROS transport into vesicles was lower in DMEM containing serum (at 4% efficiency) when compared to serum-free DMEM (at 32% efficiency). After 1 h, the rate of DCFH oxidation was found to have significantly reduced. Based upon a synthesis of these data with results from the open literature, the authors speculate on how the components of biological fluid and cellular membranes might affect the kinetics of consumption of plasma generated ROS. PMID:25910641

  17. The Effect of Sustained Compression on Oxygen Metabolic Transport in the Intervertebral Disc Decreases with Degenerative Changes

    PubMed Central

    Malandrino, Andrea; Noailly, Jérôme; Lacroix, Damien

    2011-01-01

    Intervertebral disc metabolic transport is essential to the functional spine and provides the cells with the nutrients necessary to tissue maintenance. Disc degenerative changes alter the tissue mechanics, but interactions between mechanical loading and disc transport are still an open issue. A poromechanical finite element model of the human disc was coupled with oxygen and lactate transport models. Deformations and fluid flow were linked to transport predictions by including strain-dependent diffusion and advection. The two solute transport models were also coupled to account for cell metabolism. With this approach, the relevance of metabolic and mechano-transport couplings were assessed in the healthy disc under loading-recovery daily compression. Disc height, cell density and material degenerative changes were parametrically simulated to study their influence on the calculated solute concentrations. The effects of load frequency and amplitude were also studied in the healthy disc by considering short periods of cyclic compression. Results indicate that external loads influence the oxygen and lactate regional distributions within the disc when large volume changes modify diffusion distances and diffusivities, especially when healthy disc properties are simulated. Advection was negligible under both sustained and cyclic compression. Simulating degeneration, mechanical changes inhibited the mechanical effect on transport while disc height, fluid content, nucleus pressure and overall cell density reductions affected significantly transport predictions. For the healthy disc, nutrient concentration patterns depended mostly on the time of sustained compression and recovery. The relevant effect of cell density on the metabolic transport indicates the disturbance of cell number as a possible onset for disc degeneration via alteration of the metabolic balance. Results also suggest that healthy disc properties have a positive effect of loading on metabolic transport. Such

  18. A potentiostatic study of oxygen transport through poly(2-ethoxyethyl methacrylate-co-2,3-dihydroxypropylmethacrylate) hydrogel membranes.

    PubMed

    Compañ, Vicente; Tiemblo, Pilar; García, F; García, J M; Guzmán, Julio; Riande, Evaristo

    2005-06-01

    The oxygen permeability and diffusion coefficients of hydrogel membranes prepared with copolymers of 2-ethoxyethyl methacrylate (EEMA)/2,3-dihydroxypropylmethacrylate (MAG) with mole fraction of the second monomer in the range between 0 and 0.75 are described. Values of the permeability and diffusion coefficients of oxygen are determined by using electrochemical procedures involving the measurement of the steady-state current in membranes prepared by radical polymerization of the monomers. The results obtained for the transport properties were analyzed taking into account the fractional free volumes, the cohesive energy densities and the glass transition temperatures of the hydrogels. PMID:15626426

  19. Oxygen transport through soft contact lens and cornea: Lens characterization and metabolic modeling

    NASA Astrophysics Data System (ADS)

    Chhabra, Mahendra

    The human cornea requires oxygen to sustain metabolic processes critical for its normal functioning. Any restriction to corneal oxygen supply from the external environment (e.g., by wearing a low oxygen-permeability contact lens) can lead to hypoxia, which may cause corneal edema (swelling), limbal hyperemia, neovascularization, and corneal acidosis. The need for adequate oxygen to the cornea is a major driving force for research and development of hypertransmissible soft contact lenses (SCLs). Currently, there is no standard technique for measuring oxygen permeability (Dk) of hypertransmissible silicone-hydrogel SCLs. In this work, an electrochemistry-based polarographic apparatus was designed, built, and operated to measure oxygen permeability in hypertransmissible SCLs. Unlike conventional methods where a range of lens thickness is needed for determining oxygen permeabilities of SCLs, this apparatus requires only a single lens thickness. The single-lens permeameter provides a reliable, efficient, and economic tool for measuring oxygen permeabilities of commercial hypertransmissible SCLs. The single-lens permeameter measures not only the product Dk, but, following modification, it measures separately diffusivity, D, and solubility, k, of oxygen in hypertransmissible SCLs. These properties are critical for designing better lens materials that ensure sufficient oxygen supply to the cornea. Metabolism of oxygen in the cornea is influenced by contact-lens-induced hypoxia, diseases such as diabetes, surgery, and drug treatment, Thus, estimation of the in-vivo corneal oxygen consumption rate is essential for gauging adequate oxygen supply to the cornea. Therefore, we have developed an unsteady-state reactive-diffusion model for the cornea-contact-lens system to determine in-vivo human corneal oxygen-consumption rate. Finally, a metabolic model was developed to determine the relation between contact-lens oxygen transmissibility (Dk/L) and corneal oxygen deficiency. A

  20. The role of facilitated diffusion in oxygen transport by cell-free hemoglobins: implications for the design of hemoglobin-based oxygen carriers.

    PubMed

    McCarthy, M R; Vandegriff, K D; Winslow, R M

    2001-08-30

    We compared rates of oxygen transport in an in vitro capillary system using red blood cells (RBCs) and cell-free hemoglobins. The axial PO(2) drop down the capillary was calculated using finite-element analysis. RBCs, unmodified hemoglobin (HbA(0)), cross-linked hemoglobin (alpha alpha-Hb) and hemoglobin conjugated to polyethylene-glycol (PEG-Hb) were evaluated. According to their fractional saturation curves, PEG-Hb showed the least desaturation down the capillary, which most closely matched the RBCs; HbA(0) and alpha alpha-Hb showed much greater desaturation. A lumped diffusion parameter, K*, was calculated based on the Fick diffusion equation with a term for facilitated diffusion. The overall rates of oxygen transfer are consistent with hemoglobin diffusion rates according to the Stokes-Einstein Law and with previously measured blood pressure responses in rats. This study provides a conceptual framework for the design of a 'blood substitute' based on mimicking O(2) transport by RBCs to prevent autoregulatory changes in blood flow and pressure. PMID:11527583

  1. Scaling laws for oxygen transport across the space-filling system of respiratory membranes in the human lung

    NASA Astrophysics Data System (ADS)

    Hou, Chen

    Space-filling fractal surfaces play a fundamental role in how organisms function at various levels and in how structure determines function at different levels. In this thesis, we develop a quantitative theory of oxygen transport to and across the surface of the highly branched, space-filling system of alveoli, the fundamental gas exchange unit (acinar airways), in the human lung. Oxygen transport in the acinar airways is by diffusion, and we treat the two steps---diffusion through the branched airways, and transfer across the alveolar membranes---as a stationary diffusion-reaction problem, taking into account that there may be steep concentration gradients between the entrance and remote alveoli (screening). We develop a renormalization treatment of this screening effect and derive an analytic formula for the oxygen current across the cumulative alveolar membrane surface, modeled as a fractal, space-filling surface. The formula predicts the current from a minimum of morphological data of the acinus and appropriate values of the transport parameters, through a number of power laws (scaling laws). We find that the lung at rest operates near the borderline between partial screening and no screening; that it switches to no screening under exercise; and that the computed currents agree with measured values within experimental uncertainties. From an analysis of the computed current as a function of membrane permeability, we find that the space-filling structure of the gas exchanger is simultaneously optimal with respect to five criteria. The exchanger (i) generates a maximum oxygen current at minimum permeability; (ii) 'wastes' a minimum of surface area; (iii) maintains a minimum residence time of oxygen in the acinar airways; (iv) has a maximum fault tolerance to loss of permeability; and (v) generates a maximum current increase when switching from rest to exercise.

  2. Curriculum Design of a Flipped Classroom to Enhance Haematology Learning

    ERIC Educational Resources Information Center

    Porcaro, Pauline A.; Jackson, Denise E.; McLaughlin, Patricia M.; O'Malley, Cindy J.

    2016-01-01

    A common trend in higher education is the "flipped" classroom, which facilitates active learning during class. The flipped approach to teaching was instituted in a haematology "major" class and the students' attitudes and preferences for the teaching materials were surveyed. The curriculum design was explicit and involved four…

  3. The Potential Role of Aurora Kinase Inhibitors in Haematological Malignancies

    PubMed Central

    Farag, Sherif S.

    2011-01-01

    Summary Aurora kinases play an important role in the control of the cell cycle and have been implicated in tumourigenesis in a number of cancers. Among the haematological malignancies, overexpression of Aurora kinases has been reported in acute myeloid leukaemia, chronic myeloid leukaemia, acute lymphoblastic leukaemia, multiple myeloma, aggressive non-Hodgkin lymphoma and Hodgkin lymphoma. A large number of Aurora kinase inhibitors are currently in different stages of clinical development. In addition to varying in their selectivity for the different Aurora kinases, some also have activity directed at other cellular kinases involved in important molecular pathways in cancer cells. This review summarizes the biology of Aurora kinases and discusses why they may be good therapeutic targets in different haematological cancers. We describe preclinical data that has served as the rationale for investigating Aurora kinase inhibitors in different haematological malignancies, and summarize published results from early phase clinical trials. While the anti-tumour effects of Aurora kinase inhibitors appear promising, we highlight important issues for future clinical research and suggest that the optimal use of these inhibitors is likely to be in combination with cytotoxic agents already in use for the treatment of various haematological cancers. PMID:21980926

  4. A method for estimating the volume of oxygen required by Channel Catfish Ictalurus Punctatus and Blue Catfish Ictalurus Furcatus, during transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most transporters of live fish provide supplemental aeration by diffusing pure oxygen in hauling tanks. Transporters typically use a thumb rule approach, in which knowledge of a particular species, ambient air temperature, haul tank water temperature, loading density, and transport time are consider...

  5. 76 FR 12556 - Airworthiness Directives; Various Transport Category Airplanes Equipped With Chemical Oxygen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-08

    ... 12866, (2) Is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034... Category Airplanes Equipped With Chemical Oxygen Generators Installed in a Lavatory AGENCY: Federal... affected airplanes identified above. This AD requires modifying the chemical oxygen generators in...

  6. Sufficient oxygen can be transported to resting skeletal muscle via arterialization of the vein: theoretical considerations in a rat model.

    PubMed

    Koyama, Tomiyasu; Koyama, Tomiyasu; Sasajima, Tadahiro

    2011-01-01

    The blood supply to the lower limbs is often interrupted in patients suffering from arteriosclerosis obliterans (AO). In this condition, it is necessary to establish an oxygen supply via an alternative route. In the present theoretical study on rats, the possibility that adequate oxygen could be supplied through the venous system has been considered using simple calculations. The study was undertaken in the light of a report of a successful surgical approach in which the capillary bed is bypassed [1].The total lengths of the collecting venules and of the arcade venules per mm3 are reported to be 2.32 and 2.11 mm, respectively [2]. If these vessels were stretched out and connected to form a single, narrow venular tube, the total density would be 4.43 mm/mm(3). From the reciprocal of this value, the tissue cylinder surrounding the venule would have a radius of 268 µm. Taking an oxygen consumption rate for resting skeletal muscle of 0.16 ml/100g/min, and pO2 value of 40 mmHg, the one-dimensional diffusion equation gives a maximal diffusion distance of 328 µm. This is larger than the radius of the tissue cylinder surrounding the venular tube. A calculation for Krogh's tissue cylinder gives an oxygen partial pressure gradient of 54 mmHg between the inflow and the outflow terminals. These calculations suggest the oxygen content of the venous blood is adequate to supply sufficient oxygen to resting skeletal muscle. This is consistent with the successful outcome in patients with direct A-V anastomoses and implies that the capillary network is not essential for oxygen transport to resting skeletal muscle. PMID:21445806

  7. Haematological parameters in Umbrina cirrosa (Teleostei, Sciaenidae): a comparison between diploid and triploid specimens.

    PubMed

    Ballarin, Loriano; Dall'Oro, Manuela; Bertotto, Daniela; Libertini, Angelo; Francescon, Antonia; Barbaro, Alvise

    2004-05-01

    Haematological features were compared between diploid and triploid specimens of the ray-finned fish Umbrina cirrosa. No significant differences between diploids and triploids were reported in haematocrit and total haemoglobin concentration, but erythrocytes and thrombocytes were significantly greater in size in triploids. Glycaemia was significantly lower in diploids, whereas triploid erythrocytes were more resistant to osmotic stress. In triploids, a greater fraction of leukocytes was positive for alkaline phosphatase activity, when stimulated with Bacillus clausii spores, otherwise no significant increase of oxygen consumption was observed in triploid leukocytes after stimulation, based on assays for superoxide anions. Triploids were characterized by a lower concentration of circulating blood cells with a lower surface/volume ratio when compared with diploids. These features may lead to a general disadvantage of triploids in withstanding stress conditions: a situation that needs to be taken into account in aquaculture practice. PMID:15165570

  8. Structural features and enhanced high-temperature oxygen ion transport in SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}}

    SciTech Connect

    Markov, Alexey A.; Shalaeva, Elizaveta V.; Tyutyunnik, Alexander P.; Kuchin, Vasily V.; Patrakeev, Mikhail V.; Leonidov, Ilya A.; Kozhevnikov, Victor L.

    2013-01-15

    Structural features, oxygen non-stoichiometry and transport properties are studied in the oxide series SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}}, where x=0.2, 0.3 and 0.4. X-ray diffraction and electron microscopy data evidence formation of the inhomogeneous materials at x=0.3 and 0.4, which include phase constituents with a cubic perovskite and a double perovskite structure types. The composition, the amount and the typical grain size of the phase inhomogeneities are shown to depend both on doping and oxygen content. The increased oxygen-ion conductivity is observed in oxygen depleted materials, which is explained by the increase in the amount of cubic perovskite-like phase and development of interfacial pathways favorable for enhanced oxygen ion transport. - Graphical abstract: The structural studies, oxygen content and conductivity measurements suggest that oxygen depletion from the double perovskite phase constituent of SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}} for x>0.2 is accompanied by formation of pathways for fast ion transport. Black-Small-Square Highlights: Black-Right-Pointing-Pointer The double perovskite type regions are shown to exist in SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}}. Black-Right-Pointing-Pointer The oxygen depletion is accompanied with phase separation. Black-Right-Pointing-Pointer The phase separation favors formation of pathways for enhanced oxygen ion transport.

  9. Blood flow mechanics and oxygen transport and delivery in the retinal microcirculation: multiscale mathematical modeling and numerical simulation.

    PubMed

    Causin, Paola; Guidoboni, Giovanna; Malgaroli, Francesca; Sacco, Riccardo; Harris, Alon

    2016-06-01

    The scientific community continues to accrue evidence that blood flow alterations and ischemic conditions in the retina play an important role in the pathogenesis of ocular diseases. Many factors influence retinal hemodynamics and tissue oxygenation, including blood pressure, blood rheology, oxygen arterial permeability and tissue metabolic demand. Since the influence of these factors on the retinal circulation is difficult to isolate in vivo, we propose here a novel mathematical and computational model describing the coupling between blood flow mechanics and oxygen ([Formula: see text]) transport in the retina. Albeit in a simplified manner, the model accounts for the three-dimensional anatomical structure of the retina, consisting in a layered tissue nourished by an arteriolar/venular network laying on the surface proximal to the vitreous. Capillary plexi, originating from terminal arterioles and converging into smaller venules, are embedded in two distinct tissue layers. Arteriolar and venular networks are represented by fractal trees, whereas capillary plexi are represented using a simplified lumped description. In the model, [Formula: see text] is transported along the vasculature and delivered to the tissue at a rate that depends on the metabolic demand of the various tissue layers. First, the model is validated against available experimental results to identify baseline conditions. Then, a sensitivity analysis is performed to quantify the influence of blood pressure, blood rheology, oxygen arterial permeability and tissue oxygen demand on the [Formula: see text] distribution within the blood vessels and in the tissue. This analysis shows that: (1) systemic arterial blood pressure has a strong influence on the [Formula: see text] profiles in both blood and tissue; (2) plasma viscosity and metabolic consumption rates have a strong influence on the [Formula: see text] tension at the level of the retinal ganglion cells; and (3) arterial [Formula: see text

  10. Influence of temperature on oxygen permeation through ion transport membrane to feed a biomass gasifier

    NASA Astrophysics Data System (ADS)

    Antonini, T.; Foscolo, P. U.; Gallucci, K.; Stendardo, S.

    2015-11-01

    Oxygen-permeable perovskite membranes with mixed ionic-electronic conducting properties can play an important role in the high temperature separation of oxygen from air. A detailed design of a membrane test module is presented, useful to test mechanical resistance and structural stability of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) capillary membrane in the reactor environment. Preliminary experimental results of membrane permeation tests highlight the positive effect of temperature on perovskite materials. This behaviour is also confirmed by a computational model of char combustion with oxygen permeated through the membrane module, when it is placed inside a gasifier reactor to provide the necessary input of heat to the gasification endothermic process. The results show that the temperature affects the oxygen permeation of the BSCF membrane remarkably.

  11. The Role of Oxygen Partial Pressure in Controlling the Phase Composition of La1- x Sr x Co y Fe1- y O3- δ Oxygen Transport Membranes Manufactured by Means of Plasma Spray-Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Marcano, D.; Mauer, G.; Sohn, Y. J.; Vaßen, R.; Garcia-Fayos, J.; Serra, J. M.

    2016-04-01

    La0.58Sr0.4Co0.2Fe0.8O3 - δ (LSCF) deposited on a metallic porous support by plasma spray-physical vapor deposition is a promising candidate for oxygen-permeation membranes. Ionic transport properties are regarded to depend on the fraction of perovskite phase present in the membrane. However, during processing, the LSCF powder decomposes into perovskite and secondary phases. In order to improve the ionic transport properties of the membranes, spraying was carried out at different oxygen partial pressures p(O2). It was found that coatings deposited at lower and higher oxygen partial pressures consist of 70% cubic/26% rhombohedral and 61% cubic/35% rhombohedral perovskite phases, respectively. During annealing, the formation of non-perovskite phases is driven by oxygen non-stoichiometry. The amount of oxygen added during spraying can be used to increase the perovskite phase fraction and suppress the formation of non-perovskite phases.

  12. In vivo oxygen transport in the normal rabbit femoral arterial wall.

    PubMed Central

    Crawford, D W; Back, L H; Cole, M A

    1980-01-01

    In vivo measurements of tissue oxygen tension were made at 10-micrometer intervals through functioning in situ rabbit femoral arterial walls, using inhalation anesthesia and recessed microcathodes with approximately 4-micrometer external diameters. External environment was controlled with a superfusion well at 30 torr PO2, 35 torr PCO2. Blood pressure, gas tension levels, and blood pH were held within the normal range. Radial PO2 measurements closely fit a mathematical model for unidimensional diffusion into a thick-walled artery with uniform oxygen consumption, and the distances traversed fit measured dimensions of quick-frozen in vivo sections. Using standard values of diffusion and solubility coefficients, mean calculated medial oxygen consumption was 99 nl0/ml-s. Mural oxygen consumption appeared to be related linearly to mean tangential wall stress. Differences in experimental design and technique were compared with previous in vivo and in vitro measurements of wall oxygenation, and largely account for the varying results obtained. Control of environment external to the artery, and maintenance of normally flowing blood in the lumen in vivo appeared critical to an understanding of mural oxygenation in life. If the conditions of this experiment prevailed in arteries with thicker avascular layers, PO2 could have been 20 torr at approximately 156 micrometer and 10 torr at 168 micrometer from blood (average values). Images PMID:7410554

  13. The effect of in-plane arterial curvature on blood flow and oxygen transport in arterio-venous fistulae

    PubMed Central

    Iori, F.; Grechy, L.; Gedroyc, W.; Duncan, N.; Caro, C. G.; Vincent, P. E.

    2015-01-01

    Arterio-Venous Fistulae (AVF) are the preferred method of vascular access for patients with end stage renal disease who need hemodialysis. In this study, simulations of blood flow and oxygen transport were undertaken in various idealized AVF configurations. The objective of the study was to understand how arterial curvature affects blood flow and oxygen transport patterns within AVF, with a focus on how curvature alters metrics known to correlate with vascular pathology such as Intimal Hyperplasia (IH). If one subscribes to the hypothesis that unsteady flow causes IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto the outer-curvature of a curved artery. However, if one subscribes to the hypothesis that low wall shear stress and/or low lumen-to-wall oxygen flux (leading to wall hypoxia) cause IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto a straight artery, or the inner-curvature of a curved artery. We note that the recommendations are incompatible—highlighting the importance of ascertaining the exact mechanisms underlying development of IH in AVF. Nonetheless, the results clearly illustrate the important role played by arterial curvature in determining AVF hemodynamics, which to our knowledge has been overlooked in all previous studies. PMID:25829837

  14. Unusual magnetic and transport properties of oxygen deficient Sr2Fe1-xCoxMoO6-d

    NASA Astrophysics Data System (ADS)

    Chang, Hong; García-Hernández, Mar; Alonso, Jose Antonio

    2006-10-01

    In the title compounds the oxygen voids have a significant influence over the transport properties, compared with the parent stoichiometric compounds (Sr2FeMoO6 and Sr2CoMoO6) where the oxygen defects have little impact on the crystallographic and magnetic properties. For Sr2FeMoO6-d and Sr2Fe0.95Co0.05MoO6-d, the oxygen voids simply decrease the magnetoresistance (MR) without altering the contours, and for x ⩾0.1 at the expense of the decreased low field MR, the oxygen voids enhance MR at high applied field, which is 6%-8% larger than the parent compounds for 0.2⩽x⩽0.7. Remarkably enough, the antiferromagnetic Sr2Fe0.1Co0.9MoO6-d exhibits record negative magnetoresistance ratio MR =((R(H,T)-R(0,T))/R(0,T))×100% as high as 99%.

  15. The role of extracellular histones in haematological disorders.

    PubMed

    Alhamdi, Yasir; Toh, Cheng-Hock

    2016-06-01

    Over the past decades, chromosomal alterations have been extensively investigated for their pathophysiological relevance in haematological malignancies. In particular, epigenetic modifications of intra-nuclear histones are now known as key regulators of healthy cell cycles that have also evolved into novel therapeutic targets for certain blood cancers. Thus, for most haematologists, histones are DNA-chained proteins that are buried deep within chromatin. However, the plot has deepened with recent revelations on the function of histones when unchained and released extracellularly upon cell death or from activated neutrophils as part of neutrophil extracellular traps (NETs). Extracellular histones and NETs are increasingly recognized for profound cytotoxicity and pro-coagulant effects. This article highlights the importance of recognizing this new paradigm of extracellular histones as a key player in host defence through its damage-associated molecular patterns, which could translate into novel diagnostic and therapeutic biomarkers in various haematological and critical disorders. PMID:27062156

  16. Atomic oxygen between 80 and 120 km: Evidence for a rapid spatial variation in vertical transport near the ionosphere

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Wasser, B.

    1977-01-01

    Analysis of OGO-6 OI green line photometer results was carried out for 8 cases when the alignment of the spacecraft was such that local emission rates could be determined below the altitude of maximum emission and down to about 80 km. Results show a variation on a scale of 6 deg to 8 deg in latitude between regions where the emission rate increases rapidly between 90 and 95 km and regions where it increases slowly from 80 km to 95 km. Latitude-altitude maps of iso-emissivity contours and iso-density contours for oxygen concentration are presented. The latter are computed under 3 assumptions concerning excitation mechanisms. Comparisons of the spatial variations of oxygen density with the results of a time dependent theory suggest the regions of strong downward transport alternate on a scale of about 1000 km with regions of weak transport near 90 km. In the first case conversion of O to O3 at night appears to be overwhelmed by downward transport of O.

  17. Thermochemical conversion of biomass in smouldering combustion across scales: The roles of heterogeneous kinetics, oxygen and transport phenomena.

    PubMed

    Huang, Xinyan; Rein, Guillermo

    2016-05-01

    The thermochemical conversion of biomass in smouldering combustion is investigated here by combining experiments and modeling at two scales: matter (1mg) and bench (100g) scales. Emphasis is put on the effect of oxygen (0-33vol.%) and oxidation reactions because these are poorly studied in the literature in comparison to pyrolysis. The results are obtained for peat as a representative biomass for which there is high-quality experimental data published previously. Three kinetic schemes are explored, including various steps of drying, pyrolysis and oxidation. The kinetic parameters are found using the Kissinger-Genetic Algorithm method, and then implemented in a one-dimensional model of heat and mass transfer. The predictions are validated with thermogravimetric and bench-scale experiments and then analyzed to unravel the role of heterogeneous reaction. This is the first time that the influence of oxygen on biomass smouldering is explained in terms of both chemistry and transport phenomena across scales. PMID:26901090

  18. Changes in haematological profile of common pheasant (Phasianus colchicus) induced by transit to pheasantry.

    PubMed

    Voslarova, E; Bedanova, I; Vecerek, V; Pistekova, V; Chloupek, P; Suchy, P

    2006-10-01

    The aim of this study was to assess haematological changes in hand-reared pheasants (Phasianus colchicus) transported from intensive housing facilities to a pheasantry. Selected haematological parameters were monitored in a group of 100 pheasants (50 males and 50 females) aged of 9 weeks that were transported for 4 hours by a covered lorry in crates, with a total body weight of 12 +/- 0.5 kg per crate (Group C12 - floor space: 290 cm2/kg) and with a total body weight of 18 +/- 0.5 kg per crate (Group C18 - floor space: 195 cm2/kg). Blood samples were taken from 10 randomly selected males and 10 females before transport (CON group) and 20 hours after transport (C12 and C18 groups). Examinations consisted in determining the total erythrocyte and leukocyte counts, haematocrit values, haemoglobin levels and differential leukocyte counts, whereby the proportions of heterophil, basophil and eosinophil granulocytes, lymphocytes and monocytes of the total leukocytes were computed. The changes in the parameters of red blood cell count were manifested by an increase (P < 0.01) in the haemoglobin level, MCH (mean cell haemoglobin) and MCHC (mean cell haemoglobin concentration) values and a decrease (P < 0.01) in the total erythrocyte count and haematocrit level in both C12 and C18 pheasants, when compared with the control group of non-transported pheasants. C18 pheasants exhibited also a significant increase (P < 0.05) in MCV (mean cell value) value. When analyzing differential leukocyte counts, C18 pheasants showed a decrease (P < 0.01) in heterophil counts and H/L ratio, whereas values in C12 pheasants did not differ from the non-transported control group. Individual counts of lymphocytes were decreased (P < 0.05) in C12 pheasants, whereas basophil counts were increased (P < 0.01) in both C12 and C18 pheasants. Total leukocyte count was decreased (P < 0.01) in C12 and C18 pheasants. In conclusion, the specific requirements of pheasants, as primarily wild animals, for the

  19. Oxygen Dependence and Extravascular Transport of Hypoxia-Activated Prodrugs: Comparison of the Dinitrobenzamide Mustard PR-104A and Tirapazamine

    SciTech Connect

    Hicks, Kevin O. Myint, Hilary; Patterson, Adam V.; Pruijn, Frederik B.; Siim, Bronwyn G.; Patel, Kashyap; Wilson, William R.

    2007-10-01

    Purpose: To compare oxygen dependence and tissue transport properties of a new hypoxia-activated prodrug, PR-104A, with tirapazamine, and to evaluate the implications for antitumor activity when combined with radiotherapy. Methods and Materials: Oxygen dependence of cytotoxicity was measured by clonogenic assay in SiHa cell suspensions. Tissue transport parameters were determined using SiHa multicellular layers. Spatially resolved pharmacokinetic (PK) and pharmacodynamic (PD) models were developed to predict cell killing in SiHa tumors and tested by clonogenic assay 18 h after treatment with the corresponding phosphate ester, PR-104. Results: The K-value (oxygen concentration to halve cytotoxic potency) of PR-104A was 0.126 {+-} 0.021 {mu}M (10-fold lower than tirapazamine at 1.30 {+-} 0.28 {mu}M). The diffusion coefficient of PR-104A in multicellular layers (4.42 {+-} 0.15 x 10{sup -7} cm{sup 2} s{sup -1}) was lower than that of tirapazamine (1.30 {+-} 0.05 x 10{sup -6} cm{sup 2} s{sup -1}) but PK modeling predicted better penetration to hypoxic cells in tumors because of its slower metabolism. The tirapazamine PK/PD model successfully predicted the measured activity in combination with single-dose radiation against SiHa tumors, and the PR-104A model underpredicted the activity, which was greater for PR-104 than for tirapazamine (at equivalent host toxicity) both with radiation and as a single agent. Conclusion: PR-104/PR-104A has different PK/PD properties from tirapazamine and superior activity with single-dose radiotherapy against SiHa xenografts. We have inferred that PR-104A is better able to kill cells at intermediate partial pressure of oxygen in tumors than implied by the PK/PD model, most likely because of a bystander effect resulting from diffusion of its activated metabolites from severely hypoxic zones.

  20. Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

    NASA Astrophysics Data System (ADS)

    Fan, E. S. C.; Kesler, O.

    2015-08-01

    Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

  1. Transport dynamics of a high-power-density matrix-type hydrogen-oxygen fuel cell

    NASA Technical Reports Server (NTRS)

    Prokopius, P. R.; Hagedorn, N. H.

    1974-01-01

    Experimental transport dynamics tests were made on a space power fuel cell of current design. Various operating transients were introduced and transport-related response data were recorded with fluidic humidity sensing instruments. Also, sampled data techniques were developed for measuring the cathode-side electrolyte concentration during transient operation.

  2. Blood oxygen transport and metabolism of the confined lugworm Arenicola marina (L.).

    PubMed

    Toulmond, A

    1975-12-01

    Oxygen consumption (MO2), haemoglobin oxygen saturation level (SVO2) and pH (pHv) in prebranchial blood were measured in lugworms experimentally confined in sea water at 15 degrees C. Total blood flow through the gills (Vb) was estimated. For sea water oxygen partial pressure (PwO2) between 120 and 150 Torr MO2, SVO2 and Vb were high and nearly constant. For PwO2 less than 120 Torr, Vb fell quickly, MO2 progressively dropped, and metabolism remained aerobic at the expense of the prebrancial blood oxygen store. For PwO2 less than 50 Torr, Vb and SvO2 values were extremely low, and the low pHv and the modified buffer power of the surrounding sea water showed that anaerobic metabolism was occurring. Changes in respiratory gas exchanges and metabolism during the tidal cycle are deduced from the comparison of these results with data obtained in the field. PMID:2646

  3. 78 FR 1765 - Requirements for Chemical Oxygen Generators Installed on Transport Category Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ... Statement can be found in the Federal Register published on April 11, 2000 (65 FR 19477-19478), as well as..., Security Considerations for Lavatory Oxygen Systems (76 FR 12550, March 8, 2011), Docket No. FAA-2011-0186... Airplanes (77 FR 38000, June 26, 2012). Several years ago in an unrelated initiative, the FAA tasked...

  4. Haematology and Serum Biochemistry Parameters and Variations in the Eurasian Beaver (Castor fiber).

    PubMed

    Girling, Simon J; Campbell-Palmer, Roisin; Pizzi, Romain; Fraser, Mary A; Cracknell, Jonathan; Arnemo, Jon; Rosell, Frank

    2015-01-01

    Haematology parameters (N = 24) and serum biochemistry parameters (N = 35) were determined for wild Eurasian beavers (Castor fiber), between 6 months - 12 years old. Of the population tested in this study, N = 18 Eurasian beavers were from Norway and N = 17 originating from Bavaria but now living extensively in a reserve in England. All blood samples were collected from beavers via the ventral tail vein. All beavers were chemically restrained using inhalant isoflurane in 100% oxygen prior to blood sampling. Results were determined for haematological and serum biochemical parameters for the species and were compared between the two different populations with differences in means estimated and significant differences being noted. Standard blood parameters for the Eurasian beaver were determined and their ranges characterised using percentiles. Whilst the majority of blood parameters between the two populations showed no significant variation, haemoglobin, packed cell volume, mean cell haemoglobin and white blood cell counts showed significantly greater values (p<0.01) in the Bavarian origin population than the Norwegian; neutrophil counts, alpha 2 globulins, cholesterol, sodium: potassium ratios and phosphorus levels showed significantly (p<0.05) greater values in Bavarian versus Norwegian; and potassium, bile acids, gamma globulins, urea, creatinine and total calcium values levels showed significantly (p<0.05) greater values in Norwegian versus Bavarian relict populations. No significant differences were noted between male and female beavers or between sexually immature (<3 years old) and sexually mature (≥3 years old) beavers in the animals sampled. With Eurasian beaver reintroduction encouraged by legislation throughout Europe, knowledge of baseline blood values for the species and any variations therein is essential when assessing their health and welfare and the success or failure of any reintroduction program. This is the first study to produce base

  5. Oxygen transport in the Sr{sub 2}Fe{sub 3{minus}x}Co{sub x}O{sub y} system.

    SciTech Connect

    Ma, B.

    1999-01-04

    The mixed-conducting Sr-Fe-Co oxide has potential use as a gas separation membrane. Its superior oxygen transport reveals the feasibility of using oxide membranes in large-scale oxygen separation. Sr{sub 2}Fe{sub 3{minus}x}Co{sub x}O{sub y} (with x = 0.0, 0.3, 0.6, and 1.0) samples were made by solid state reaction. To understand the oxygen transport mechanism in this system, conductivity and thermogravimetry experiments were conducted at high temperature in various oxygen partial pressure environments. The oxygen diffusion coefficient was determined from the time relaxation transient behavior of the specimen after switching the surrounding atmosphere. Mobility of the charge carrier was derived from relative conductivity and weight changes. X-ray diffraction experiments were carried out on these samples to determine their crystal structures.

  6. Two-dimensional concentration distribution of reactive oxygen species transported through a tissue phantom by atmospheric-pressure plasma-jet irradiation

    NASA Astrophysics Data System (ADS)

    Kawasaki, Toshiyuki; Sato, Akihiro; Kusumegi, Shota; Kudo, Akihiro; Sakanoshita, Tomohiro; Tsurumaru, Takuya; Uchida, Giichiro; Koga, Kazunori; Shiratani, Masaharu

    2016-07-01

    The two-dimensional concentration distribution of reactive oxygen species (ROSs) transported through an agarose-film tissue phantom by atmospheric-pressure plasma-jet irradiation is visualized using a KI-starch gel reagent. Oxygen addition to helium enhances ROS transportation through the film. A radial ROS distribution pattern at the plasma-irradiated film surface changes into a doughnut-shaped pattern after passing through the film. The ROS transportation speed is 0.14–0.2 mm/min. We suggest that there are two types of ROS transportation pathways in the plasma-irradiated film: linear and circular. The majority of ROSs are transported through the circular pathway. ROS concentration distributions changed markedly with irradiation distance. Diffusive ROS transportation due to a concentration gradient is negligible in plasma-irradiated films.

  7. Avoiding chromium transport from stainless steel interconnects into contact layers and oxygen electrodes in intermediate temperature solid oxide electrolysis stacks

    NASA Astrophysics Data System (ADS)

    Schlupp, Meike V. F.; Kim, Ji Woo; Brevet, Aude; Rado, Cyril; Couturier, Karine; Vogt, Ulrich F.; Lefebvre-Joud, Florence; Züttel, Andreas

    2014-12-01

    We investigated the ability of (La0.8Sr0.2)(Mn0.5Co0.5)O3-δ (LSMC) and La(Ni0.6Fe0.4)O3-δ (LNF) contact coatings to avoid the transport of Cr from steel interconnects to solid oxide electrolysis electrodes, especially to the anode. The transport of chromium from commercial Crofer 22 APU (ThyssenKrupp) and K41X (AISI441, Aperam Isbergues) steels through LSMC and LNF contact coatings into adjacent (La0.8Sr0.2)MnO3-δ (LSM) oxygen electrodes was investigated in an oxygen atmosphere at 700 °C. Chromium concentrations of up to 4 atom% were detected in the contact coatings after thermal treatments for 3000 h, which also lead to the presence of chromium in adjacent LSM electrodes. Introduction of a dense (Co,Mn)3O4 coating between steel and contact coating was necessary to prevent the diffusion of chromium into contact coatings and electrodes and should lead to extended stack performance and lifetime.

  8. Misconceptions concerning the behavior, fate and transport of the fuel oxygenates TBA and MTBE

    NASA Astrophysics Data System (ADS)

    Woodward, R.; Sloan, R.

    2003-04-01

    The release of gasoline from underground storage tanks and the subsequent appearance of dissolved constituents in drinking water has focused attention on the use of MTBE in reformulated fuels. Natural biodegradation of MTBE in soil, photo-oxidation in the atmosphere or chemical oxidation during remediation of gasoline releases can produce the intermediate tertiary butyl alcohol (TBA). TBA is also a fuel oxygenate and can be found as a co-product in MTBE synthesized from methanol and TBA. Because the physical properties of ethers and alcohols differ somewhat from the predominant hydrocarbon compounds in gasoline, misconceptions have developed about the behavior of fuel oxygenates in storage and in the subsurface. Critical review of several misconceptions about MTBE and TBA in gasoline reveals the concepts were conceived to rationalize early field observations and/or incomplete data sets. Closer scrutiny, in light of recent laboratory investigations, field data, case studies and world literature, clarifies these misconceptions and assumptions about the behavior of ether oxygenates and their degradation products in the environment. Commonly held misconceptions focus on four general areas of fuel and fuel oxygenate management: storage/dispensing, hydrology, remediation, and health effects. Storage/dispensing misconceptions address materials stability to ethers and alcohols in fuel and the environmental forensics of fuel systems failure. Groundwater and hydrology misconceptions deal with plume dynamics and the impact of fuel on drinking water resources. Remediation misconceptions focus on the performance of traditional hydrocarbon remediation technologies, recent developments in biodegradation and natural attenuation, drivers of remedial design and remediation costs. Health effects misconceptions address both acute and chronic exposure risk evaluations by national and international health agencies. Generally MTBE and TBA are manageable by the same processes and

  9. Direct Evidence of Solution-Mediated Superoxide Transport and Organic Radical Formation in Sodium-Oxygen Batteries.

    PubMed

    Xia, Chun; Fernandes, Russel; Cho, Franklin H; Sudhakar, Niranjan; Buonacorsi, Brandon; Walker, Sean; Xu, Meng; Baugh, Jonathan; Nazar, Linda F

    2016-09-01

    Advanced large-scale electrochemical energy storage requires cost-effective battery systems with high energy densities. Aprotic sodium-oxygen (Na-O2) batteries offer advantages, being comprised of low-cost elements and possessing much lower charge overpotential and higher reversibility compared to their lithium-oxygen battery cousins. Although such differences have been explained by solution-mediated superoxide transport, the underlying nature of this mechanism is not fully understood. Water has been suggested to solubilize superoxide via formation of hydroperoxyl (HO2), but direct evidence of these HO2 radical species in cells has proven elusive. Here, we use ESR spectroscopy at 210 K to identify and quantify soluble HO2 radicals in the electrolyte-cold-trapped in situ to prolong their lifetime-in a Na-O2 cell. These investigations are coupled to parallel SEM studies that image crystalline sodium superoxide (NaO2) on the carbon cathode. The superoxide radicals were spin-trapped via reaction with 5,5-dimethyl-pyrroline N-oxide at different electrochemical stages, allowing monitoring of their production and consumption during cycling. Our results conclusively demonstrate that transport of superoxide from cathode to electrolyte leads to the nucleation and growth of NaO2, which follows classical mechanisms based on the variation of superoxide content in the electrolyte and its correlation with the crystallization of cubic NaO2. The changes in superoxide content upon charge show that charge proceeds through the reverse solution process. Furthermore, we identify the carbon-centered/oxygen-centered alkyl radicals arising from attack of these solubilized HO2 species on the diglyme solvent. This is the first direct evidence of such species, which are likely responsible for electrolyte degradation. PMID:27498623

  10. Role of hemoglobin from blood clam Scapharca kagoshimensis beyond oxygen transport.

    PubMed

    Xu, Bin; Zhao, Jun; Jing, Zhao; Zhang, Yanan; Shi, Ying; Fan, Tingjun

    2015-05-01

    The evolutionary race between hosts and pathogens has led to a variety of adaptations. Little is known about the immunological role of hemoglobin (Hb) in antimicrobial immune responses. Results showed that a 31.2 kDa monodimer Hb (skHbI) and a 57.8 kDa heterotetramer Hb (skHbII) from the blood clam, Scapharca kagoshimensis, had phenoloxidase (PO)-like activities and antimicrobial activities. Both were found capable of oxidizing l-DOPA, catechol and hydroquinone. Their PO-like activities were visibly greatly inhibited by oxidase inhibitors, EDTA, and divalent metal ions, and greatly enhanced by isopropanol and Fe(2+), indicating that they have the properties of a metalloenzyme and a catecholase-type PO as well. They also showed obvious anti-bacterial activities against gram-positive bacteria but not against either gram-negative bacteria nor fungi. The anti-bacterial activities levels were a result of the generation of reactive oxygen species (ROS) of superoxide anions. These results indicate that skHbI and skHbII, not only function as iron-containing oxygen carriers, but also exert anti-bacterial activities and catecholase-type oxidizing activities. The fact that skHbII exerts high level of PO-like activity indicates different roles in the innate immunodefense system. These results may improve understanding of the multiple functions of invertebrate Hbs beyond serving as oxygen carriers and may provide insight into how the fundamental and universal mode of the innate immune system has persisted in respiratory proteins throughout the course of evolution. PMID:25700784

  11. Electrical transport properties of individual WS2 nanotubes and their dependence on water and oxygen absorption

    NASA Astrophysics Data System (ADS)

    Zhang, Chaoying; Ning, Zhiyuan; Liu, Yang; Xu, Tingting; Guo, Yao; Zak, Alla; Zhang, Zhiyong; Wang, Sheng; Tenne, Reshef; Chen, Qing

    2012-09-01

    The electrical properties of WS2 nanotubes (NTs) were studied through measuring 59 devices. Important electrical parameters, such as the carrier concentration, mobility, and effective barrier height at the contacts, were obtained through fitting experimental non-linear I-V curves using a metal-semiconductor-metal model. The carrier mobility was found to be several orders of magnitude higher than that have been reported previously for WS2 NTs. Water absorption was found to decrease the conductivity and carrier mobility of the NTs, and could be removed when the sample was dried. Oxygen absorption also slightly decreased the conductivity of WS2 NTs.

  12. Fluorination of an antiepileptic drug: A self supporting transporter by oxygen enrichment mechanism.

    PubMed

    Natchimuthu, V; Amoros, J; Ravi, S

    2016-03-01

    Drug therapy of seizures involves producing high levels of antiepileptic drugs in the blood. Drug must enter the brain by crossing from the blood into the brain tissue, called a transvascular route (TVR). Even before the drug can reach the brain tissue, factors such as systemic toxicity, macrophage phagocytises and reduction in oxygen content limit the success of this TVR. Encapsulating the drug within a nano scale delivering system, synthesising drugs with low molecular weight are the best mechanisms to deliver the drug to the brain. But through this article, we have explored a possibility of attaching a molecule 4-(trifluoromethyl) benzoic acid (TFMBA), that possess more number of fluorine atom, to benzodiazepine (BDZ) resulting in an ionic salt (S)-(+)-2,3-dihydro-1H-pyrrolo[2,1-c][1,4]benzodiazepine5,11(10H,11aH)-dione with 4-(trifluoromethyl)benzoic acid. By this way, reducing the toxicity of BDZ than the conventional anti-epileptic drugs (AEDs), increasing the solubility, reducing the melting point, enriching the TVR with excess oxygen content with the support of fluorine. With all these important prerequisites fulfilled, the drug along with the attached molecule is expected to travel more comfortably through the TVR without any external support than any other conventional AEDs. FTIR, (1)H NMR, (13)C NMR, HRMS spectroscopy, HRTEM and In vitro cytotoxicity analysis supports this study. PMID:26708322

  13. Transition of care from paediatric to adult services in haematology

    PubMed Central

    Bolton‐Maggs, Paula H B

    2007-01-01

    The need for adequate preparation for transition for young people with health care needs who require long term follow‐up in the adult sector has long been recognised and is a required part of the national service framework for children. The Royal College of Paediatrics and Child Health and the Royal College of Nursing have endorsed this need for improvement in services for adolescents. In 2006 the Department of Health launched guidelines with a wealth of recommendations. Despite these initiatives only slow progress has been made (usually by enthusiasts) and much work is needed to develop good programmes in many specialties, including non‐malignant haematology. PMID:17715443

  14. Haematological profile in leprosy. Part I--general findings.

    PubMed

    Karat, A B; Rao, P S

    1977-04-01

    Haematological studies in 904 adult leprosy patients with different types of leprosy, in various stages of the disease and treatment are described. Haemoglobin, packed cell volume, serum albumin and serum iron are significantly lower among lepromatous leprosy patients as compared with non-lepromatous patients. The serum B12 levels were significantly higher among the lepromatous group. Acid fast bacilli have been demonstrated in skin smear negative leprosy patients with indeterminate and tuberculoid leprosy, suggesting occurrence of bacillaemia in these groups of patients. PMID:909286

  15. Haematological parameters as bioindicators of insecticide exposure in teleosts.

    PubMed

    Singh, Narendra Nath; Srivastava, Anil Kumar

    2010-06-01

    Haematological parameters, such as erythrocyte and leucocyte count, erythrocyte indices and thrombocyte number vis-a-vis coagulation of blood has been considered bioindicators of toxicosis in fish following exposure to organochlorine, organophosphate, carbamate and pyrethroid insecticides. This review deals with the effects of insecticides on the morphology of red blood cells, total erythrocyte count, haemoglobin content, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, erythrocyte sedimentation rate, total and differential leucocyte counts, thrombocyte count and clotting time in the peripheral blood of a number of teleosts. The review also takes stock of knowledge of the subject and explores prospects of additional research in the related area. PMID:20177774

  16. Re-evaluation of the H+/site ratio of mitochondrial electron transport with the oxygen pulse technique.

    PubMed

    Brand, M D; Reynafarje, B; Lehninger, A L

    1976-09-25

    The number of protons ejected per pair of electrons passing each energy-conserving site in the electron transport chain (the H+/site ratio) has been investigated in rat liver mitochondria by means of the oxygen pulse technique introduced by Mitchell and Moyle (1967) (Biochem. J. 105, 1147-1162). The usual H+/site values of 2.0 observed by this method were found to be substantially underestimated as a result of the influx of phosphate into the mitochondria. This was shown by three different kinds of experiments. 1. Addition of N-ethylmaleimide or mersalyl, inhibitors of mitochondrial phosphate transport, increased the H+/site ratio from 2.0 to 3.0. The dependence of this effect on the concentration of either inhibitor was identical with that for inhibition of phosphate transport. Added phosphate diminished the H+/site ratio to values below 2.0 in the absence of N-ethylmaleimide. N-Ethylmaleimide protected the elevated H+/site ratio of 3.0 against the deleterious effect of added phosphate, but did not prevent a lowering effect of weak acid anions such as 3-hydroxybutyrate. 2. Prior washing of mitochondria to remove the endogenous phosphate that leaks out during the anaerobic preincubation led to H+/site ratios near 3.0, which were not increased by N-ethylmaleimide. Addition of low concentrations of phosphate to such phosphate-depleted mitochondria decreased the H+/site ratio to 2.0; addition of N-ethylmaleimide returned the ratio to 3.0. 3. Lowering the temperature to 5 degrees, which slows down phosphate transport, led to H+/site values of 3.0 even in the absence of N-ethylmaleimide. The H+/site ratio of 3.0 observed in the absence of phosphate movements was not dependent on any narrowly limited set of experimental conditions. It occurred with either Ca2+ or K+ (in the presence of valinomycin) as mobile permeant cation. It was independent of the concentration of succinate, oxygen, mitochondria, or rotenone, additions of Ca2+, Li+, or Na+ and was independent of

  17. Negative ion clusters in oxygen: collision cross sections and transport coefficients

    NASA Astrophysics Data System (ADS)

    de Urquijo, J.; Bekstein, A.; Ducasse, O.; Ruíz-Vargas, G.; Yousfi, M.; Benhenni, M.

    2009-12-01

    Using a pulsed Townsend experiment, we have observed the formation of two negative ion species in oxygen over the pressure range 100-600 torr, and the density-normalised electric field strength, E/N, from 2 to 14 Td. The peculiar shape of these transients has led us to propose a scheme of three-body ion-molecule reactions leading to the formation of O4 - and O6 -, which is substantiated by a curve fitting procedure. The resulting mobility data of these two ionic species have been used to calculate their respective momentum transfer collision cross sections, together with the dissociation cross sections that are needed to extend the range of calculation of mobility and diffusion (transverse and longitudinal) to 1000 Td. These calculations were based on an optimised Monte Carlo algorithm, using collision cross sections obtained from a JWKB approximation (Jeffreys-Wentzel-Kramers-Brillouin) or taken from literature.

  18. Reversible modulation of electric transport properties by oxygen absorption and releasing on Nb:SrTiO{sub 3} surface

    SciTech Connect

    Lu, H. X.; Liu, Y. B.; Chen, Y. S. Wang, J.; Shen, B. G.; Sun, J. R.

    2014-11-07

    Pt Schottky contacts on (001)-orientated Nb-doped SrTiO{sub 3} (NSTO) in both ambient air and vacuum were investigated by the conductive atomic force microscope. The co-existed TiO{sub 2} and SrO termination layers were identified on the terrace-structured NSTO surface, where the former possessed a higher forward current than the latter. In ambient air, the barrier height of Pt/NSTO Schottky junction exhibited periodical variation with cyclic terrace plane and step sites, whereas it became homogeneous in ambient vacuum. We suggested that the oxygen absorption and releasing of surface dangling bonds were the origin for reversible changes in transport properties, which indicates a feasible approach for the surface modulation and band structure tailoring of NSTO based heterojunctions.

  19. Reversible modulation of electric transport properties by oxygen absorption and releasing on Nb:SrTiO3 surface

    NASA Astrophysics Data System (ADS)

    Lu, H. X.; Liu, Y. B.; Chen, Y. S.; Wang, J.; Shen, B. G.; Sun, J. R.

    2014-11-01

    Pt Schottky contacts on (001)-orientated Nb-doped SrTiO3 (NSTO) in both ambient air and vacuum were investigated by the conductive atomic force microscope. The co-existed TiO2 and SrO termination layers were identified on the terrace-structured NSTO surface, where the former possessed a higher forward current than the latter. In ambient air, the barrier height of Pt/NSTO Schottky junction exhibited periodical variation with cyclic terrace plane and step sites, whereas it became homogeneous in ambient vacuum. We suggested that the oxygen absorption and releasing of surface dangling bonds were the origin for reversible changes in transport properties, which indicates a feasible approach for the surface modulation and band structure tailoring of NSTO based heterojunctions.

  20. Apoplasmic Barriers and Oxygen Transport Properties of Hypodermal Cell Walls in Roots from Four Amazonian Tree Species1

    PubMed Central

    De Simone, Oliviero; Haase, Karen; Müller, Ewald; Junk, Wolfgang J.; Hartmann, Klaus; Schreiber, Lukas; Schmidt, Wolfgang

    2003-01-01

    The formation of suberized and lignified barriers in the exodermis is suggested to be part of a suite of adaptations to flooded or waterlogged conditions, adjusting transport of solutes and gases in and out of roots. In this study, the composition of apoplasmic barriers in hypodermal cell walls and oxygen profiles in roots and the surrounding medium of four Amazon tree species that are subjected to long-term flooding at their habitat was analyzed. In hypodermal cell walls of the deciduous tree Crateva benthami, suberization is very weak and dominated by monoacids, 2-hydroxy acids, and ω-hydroxycarboxylic acids. This species does not show any morphological adaptations to flooding and overcomes the aquatic period in a dormant state. Hypodermal cells of Tabernaemontana juruana, a tree which is able to maintain its leaf system during the aquatic phase, are characterized by extensively suberized walls, incrusted mainly by the unsaturated C18 ω-hydroxycarboxylic acid and the α,ω-dicarboxylic acid analogon, known as typical suberin markers. Two other evergreen species, Laetia corymbulosa and Salix martiana, contained 3- to 4-fold less aliphatic suberin in the exodermis, but more than 85% of the aromatic moiety of suberin are composed of para-hydroxybenzoic acid, suggesting a function of suberin in pathogen defense. No major differences in the lignin content among the species were observed. Determination of oxygen distribution in the roots and rhizosphere of the four species revealed that radial loss of oxygen can be effectively restricted by the formation of suberized barriers but not by lignification of exodermal cell walls. PMID:12746526

  1. Apoplasmic barriers and oxygen transport properties of hypodermal cell walls in roots from four amazonian tree species.

    PubMed

    De Simone, Oliviero; Haase, Karen; Müller, Ewald; Junk, Wolfgang J; Hartmann, Klaus; Schreiber, Lukas; Schmidt, Wolfgang

    2003-05-01

    The formation of suberized and lignified barriers in the exodermis is suggested to be part of a suite of adaptations to flooded or waterlogged conditions, adjusting transport of solutes and gases in and out of roots. In this study, the composition of apoplasmic barriers in hypodermal cell walls and oxygen profiles in roots and the surrounding medium of four Amazon tree species that are subjected to long-term flooding at their habitat was analyzed. In hypodermal cell walls of the deciduous tree Crateva benthami, suberization is very weak and dominated by monoacids, 2-hydroxy acids, and omega-hydroxycarboxylic acids. This species does not show any morphological adaptations to flooding and overcomes the aquatic period in a dormant state. Hypodermal cells of Tabernaemontana juruana, a tree which is able to maintain its leaf system during the aquatic phase, are characterized by extensively suberized walls, incrusted mainly by the unsaturated C(18) omega-hydroxycarboxylic acid and the alpha,omega-dicarboxylic acid analogon, known as typical suberin markers. Two other evergreen species, Laetia corymbulosa and Salix martiana, contained 3- to 4-fold less aliphatic suberin in the exodermis, but more than 85% of the aromatic moiety of suberin are composed of para-hydroxybenzoic acid, suggesting a function of suberin in pathogen defense. No major differences in the lignin content among the species were observed. Determination of oxygen distribution in the roots and rhizosphere of the four species revealed that radial loss of oxygen can be effectively restricted by the formation of suberized barriers but not by lignification of exodermal cell walls. PMID:12746526

  2. The Ca2+/Mn2+-transporting SPCA2 pump is regulated by oxygen and cell density in colon cancer cells.

    PubMed

    Jenkins, James; Papkovsky, Dmitri B; Dmitriev, Ruslan I

    2016-08-15

    The mammalian SPCA1 and SPCA2 ATPases localize in membranes of the secretory pathway and transport ions of Ca(2+) and Mn(2+) The role of tissue-specific SPCA2 isoform, highly expressed in lungs, mammary gland and gastrointestinal tract, is poorly understood. To elucidate the function of SPCA2, we studied human colon cancer HCT116 cells, grown under ambient and decreased O2 levels. We found that in contrast with other Ca(2+)-ATPase isoforms the expression of SPCA2 was up-regulated under hypoxia (3% O2), in both adherent (2D) and spheroid (3D) cultures. In spheroids, experiencing lowest O2 levels (30-50 μM, measured by phosphorescence lifetime imaging microscopy), we observed lower staining with reactive oxygen species (ROS)-specific fluorescent probe, which correlated with increased SPCA2. However, SPCA2 expression was up-regulated in cells exposed to reactive oxygen and nitrogen species donors, and when grown at higher density. We noticed that the culture exposed to hypoxia showed overall increase in S phase-positive cells and hypothesized that SPCA2 up-regulation under hypoxia can be linked to Mn(2+)-dependent cell cycle arrest. Consequently, we found that SPCA2-transfected cells display a higher number of cells entering S phase. Altogether, our results point at the important role of SPCA2 in regulation of cell cycle in cancer cells. PMID:27316461

  3. Cerebrovascular disease as the initial clinical presentation of haematological disorders.

    PubMed

    Arboix, A; Besses, C

    1997-01-01

    We describe 14 patients (mean age 57 years) in whom stroke or TIA was the presenting manifestation of a haematologic disorder. Twelve patients had an ischaemic stroke and 2 a haemorrhagic stroke. This group represented 1.27% (14/1,099) of the total number of patients with first-ever stroke diagnosed from 1986 to 1992 at our institution, accounted for 1.32% (12/906) of all brain infarcts and 1.03% (2/193) of all haemorrhagic strokes, and was the most common aetiology (25%) of ischaemic stroke of unusual cause. Haematological disorders included essential thrombocythaemia (6), polycythaemia vera (1), smoker's polycythaemia (1), thrombotic thrombocytopenic purpura (1), IgA lambda myeloma (1), acute lymphoblastic leukaemia (1), Waldenström's macroglobulinaemia (1), chronic granulocytic leukaemia (1) and IgG lambda myeloma (1). Stroke subtypes included definitive cerebral infarct (10), TIA (2), parenchymal haemorrhage (1) and spontaneous subdural haematoma (1). Vascular territories in ischaemic stroke were the carotid in 7 patients, the vertebrobasilar in 1 and undetermined in 4. Mean follow-up was 40 months (range, 1-96 months). The mortality rate was 18.7%. PMID:9208259

  4. Haematological investigation of a multiple case leucosis herd.

    PubMed

    Dimmock, C K; Waugh, P D; Rogers, R J

    1979-06-01

    Adult cattle in a Queensland dairy herd with a history of deaths from lymphosarcoma were sampled regularly over a 4 year period for the identification of animals with persistent lymphocytosis (PL). Twenty-one of 94 animals that were sampled at least 6 times had PL. At the initial sampling 27% of the animals had lymphocytosis. Culling of haematologically positive animals in the first 18 months of the investigation reduced this to 5.3%, but cessation of the culling programme resulted in a gradual increase in the percentage of animals with lymphocytosis. Four deaths from lymphosarcoma occurred in adult animals, but only in the first 18 months of the investigation. Two of these animals had lymphocytosis and two lymphoblastic leukaemia. The calf of one of the latter cows developed lymphoblastic leukaemia and lymphosarcoma by the time it was 6 months of age. Although histological evidence of lymphosarcoma was lacking in a number of clinically normal animals with lymphocytosis, haematological investigation identified a group of animals within the herd that may develop lymphosarcoma. PMID:293162

  5. The Role of miRNA in Haematological Malignancy

    PubMed Central

    Gounaris-Shannon, Stephanie

    2013-01-01

    Currently, there are over 1,800 annotated human miRNAs, many of which have tissue-specific expression. Numerous studies have highlighted their role in haematopoietic differentiation and proliferation, acting as master regulators of haematopoietic stem cell function. Aberrant expression of miRNAs has been observed in haematological cancers, exhibiting unique expression signatures in comparison to normal counterparts. Functional and target analyses as well as animal models have attempted to annotate how different miRNA may contribute to the pathophysiology of these malignancies from modulating cancer associated genes, functioning directly as oncogenes or tumour suppressor genes or acting as bystanders or regulators of the epigenetic mechanisms in cancer. miRNAs have also been shown to play a role in modulating drug resistance and determining prognosis between the various subtypes of blood cancers. This review discusses the important role that miRNAs play in haematological malignancies by exploring associations that exist between the two and trying to examine evidence of causality to support the tantalising possibility that miRNAs might serve as therapeutic targets in blood cancers. PMID:24416592

  6. Long Non-Coding RNAs in Haematological Malignancies

    PubMed Central

    Garitano-Trojaola, Andoni; Agirre, Xabier; Prósper, Felipe; Fortes, Puri

    2013-01-01

    Long non-coding RNAs (lncRNAs) are functional RNAs longer than 200 nucleotides in length. LncRNAs are as diverse as mRNAs and they normally share the same biosynthetic machinery based on RNA polymerase II, splicing and polyadenylation. However, lncRNAs have low coding potential. Compared to mRNAs, lncRNAs are preferentially nuclear, more tissue specific and expressed at lower levels. Most of the lncRNAs described to date modulate the expression of specific genes by guiding chromatin remodelling factors; inducing chromosomal loopings; affecting transcription, splicing, translation or mRNA stability; or serving as scaffolds for the organization of cellular structures. They can function in cis, cotranscriptionally, or in trans, acting as decoys, scaffolds or guides. These functions seem essential to allow cell differentiation and growth. In fact, many lncRNAs have been shown to exert oncogenic or tumor suppressor properties in several cancers including haematological malignancies. In this review, we summarize what is known about lncRNAs, the mechanisms for their regulation in cancer and their role in leukemogenesis, lymphomagenesis and hematopoiesis. Furthermore, we discuss the potential of lncRNAs in diagnosis, prognosis and therapy in cancer, with special attention to haematological malignancies. PMID:23887658

  7. Immunophenotyping of Posttraumatic Neutrophils on a Routine Haematology Analyser

    PubMed Central

    Groeneveld, Kathelijne Maaike; Heeres, Marjolein; Leenen, Loek Petrus Hendrikus; Huisman, Albert; Koenderman, Leo

    2012-01-01

    Introduction. Flow cytometry markers have been proposed as useful predictors for the occurrence of posttraumatic inflammatory complications. However, currently the need for a dedicated laboratory and the labour-intensive analytical procedures make these markers less suitable for clinical practice. We tested an approach to overcome these limitations. Material and Methods. Neutrophils of healthy donors were incubated with antibodies commonly used in trauma research: CD11b (MAC-1), L-selectin (CD62L), FcγRIII (CD16), and FcγRII (CD32) in active form (MoPhab A27). Flow cytometric analysis was performed both on a FACSCalibur, a standard flow cytometer, and on a Cell-Dyn Sapphire, a routine haematology analyser. Results. There was a high level of agreement between the two types of analysers, with 41% for FcγRIII, 80% for L-selectin, 98% for CD11b, and even a 100% agreement for active FcγRII. Moreover, analysis on the routine haematology analyser was possible in less than a quarter of the time in comparison to the flow cytometer. Conclusion. Analysis of neutrophil phenotype on the Cell-Dyn Sapphire leads to the same conclusion compared to a standard flow cytometer. The markedly reduced time necessary for analysis and reduced labour intensity constitutes a step forward in implementation of this type of analysis in clinical diagnostics in trauma research. PMID:22523451

  8. Communication during haematological consultations; patients' preferences and professionals' performances.

    PubMed

    van Bruinessen, Inge R; van der Hout, Lotte E; van Weel-Baumgarten, Evelyn M; Gouw, Hans; Zijlstra, Josée M; van Dulmen, Sandra

    2016-06-01

    Many patients with haematological malignancies experience barriers in clinical communication. Reaching effective communication is of great importance as it has been linked to a range of improved patient outcomes such as satisfaction, compliance to treatment, perceived quality of life and physical and mental health. To get a better understanding how communication in haematological consultations can be improved, the current study focussed on patients' preferences and perceived performances regarding the communicative behaviour of their health care professional. Secondly, the mediation of an online communication tool for patients was analysed. Within a controlled pre- post-test design, 78 datasets of clinical consultations could be analysed. Patients considered both affective and instrumental communication aspects important. The affective communication behaviour of the health care professional met the patients' pre-visit preferences well. In the information exchange, more variability and discrepancies were found. Overall, the online intervention did not seem to influence the patients' perceived communication performance of their health care professional much. To further improve the communication during clinical consultations, health care professionals should inquire about patients' expectations, especially during the exchange of information and advices. At the same time, patients should be supported to express their preferences at the start of the consultation. The study was registered in the Netherlands Trial Register, number 3779. PMID:27091348

  9. Optical methods for correction of oxygen-transport characteristics of blood and their biomedical applications

    NASA Astrophysics Data System (ADS)

    Zalesskaya, G. A.; Akulich, N. V.; Marochkov, A. V.; Laskina, O. V.; Mit'kovskaya, N. P.

    2010-07-01

    We have carried out a comprehensive analysis of the spectral characteristics of blood and blood components, gas-exchange and oximetry parameters for venous and arterial blood, central hemodynamic parameters, and the results of a complete blood count and chemistry panel before and after extracorporeal UV irradiation of the blood (UBI, ultraviolet blood irradiation) or intravenous exposure of blood to low-intensity emission from an He-Ne laser (LBI, laser blood irradiation). We have demonstrated the possibility of correcting the oxygentransport characteristics of blood by laser optical methods based on photodissociation of blood oxyhemoglobin. We have shown that the therapeutic effects initiated both by UBI and LBI are based on a single mechanism: a change in the balance between production of active oxygen species and their inhibition by antioxidants. The data obtained are of interest not only for studying the primary (molecular) mechanisms of action for photohemotherapy and their effect on processes occurring in the living body, but also can provide a basis for designing next-generation laser optical instruments and for development of not yet existing methods for assessing the therapeutic efficacy of photohemotherapy.

  10. Transport properties for liquid silicon-oxygen-iron mixtures at Earth's core conditions

    NASA Astrophysics Data System (ADS)

    Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario

    2013-01-01

    We report on the thermal and electrical conductivities of two liquid silicon-oxygen-iron mixtures (Fe0.82Si0.10O0.08 and Fe0.79Si0.08O0.13), representative of the composition of the Earth's outer core at the relevant pressure-temperature conditions, obtained from density functional theory calculations with the Kubo-Greenwood formulation. We find thermal conductivities k=100(160) W m-1 K-1, and electrical conductivities σ=1.1(1.3)×106Ω-1 m-1 at the top (bottom) of the outer core. These values are between two and three times higher than previous estimates, and have important implications for our understanding of the Earth's thermal history and the functioning of the Earth's magnetic field, including rapid cooling rate for the whole core or high level of radiogenic elements in the core. We also show results for a number of structural and dynamic properties of the mixtures, including the partial radial distribution functions, mean square displacements, viscosities, and speeds of sound.

  11. Effect of intermittent hypoxia and exercise on blood rheology and oxygen transport in trained rats.

    PubMed

    Núñez-Espinosa, Cristian; Douziech, Anne; Ríos-Kristjánsson, Juan Gabriel; Rizo, David; Torrella, Joan Ramon; Pagès, Teresa; Viscor, Ginés

    2014-02-01

    Intermittent hypobaric hypoxia (IHH) exposure, accompanied or not with active recovery, can help to skeletal muscle repair. However, the erythropoietic response elicited can disturb blood rheology and thus alter the oxygen delivery to tissues. Male Sprague-Dawley rats were studied in two basal states: untrained and trained and compared with early (1-3 days) and late (7-14 days) stages of damage recovery in three groups of trained rats that had suffered skeletal muscle injury: Control, passive recovery rats; HYP, rats exposed to IHH after muscle damage; and EHYP, trained rats that performed light aerobic exercise sessions in addition to IHH. Hematocrit, RBC count and hemoglobin were only elevated in the late stage of recovery in HYP (13%; 14% and 8%) and EHYP (18%; 13% and 15%) groups. Blood viscosity increased about double for EHYP rats. It is concluded that intermittent exposure to hypobaric hypoxia in combination with light aerobic exercise in normoxia has an erythropoietic effect, but also provides advantageous hemorheological conditions for the perfusion of damaged muscle. PMID:24373840

  12. Economical Speed and Energetically Optimal Transition Speed Evaluated by Gross and Net Oxygen Cost of Transport at Different Gradients

    PubMed Central

    Abe, Daijiro; Fukuoka, Yoshiyuki; Horiuchi, Masahiro

    2015-01-01

    The oxygen cost of transport per unit distance (CoT; mL·kg-1·km-1) shows a U-shaped curve as a function of walking speed (v), which includes a particular walking speed minimizing the CoT, so called economical speed (ES). The CoT-v relationship in running is approximately linear. These distinctive walking and running CoT-v relationships give an intersection between U-shaped and linear CoT relationships, termed the energetically optimal transition speed (EOTS). This study investigated the effects of subtracting the standing oxygen cost for calculating the CoT and its relevant effects on the ES and EOTS at the level and gradient slopes (±5%) in eleven male trained athletes. The percent effects of subtracting the standing oxygen cost (4.8 ± 0.4 mL·kg-1·min-1) on the CoT were significantly greater as the walking speed was slower, but it was not significant at faster running speeds over 9.4 km·h-1. The percent effect was significantly dependent on the gradient (downhill > level > uphill, P < 0.001). The net ES (level 4.09 ± 0.31, uphill 4.22 ± 0.37, and downhill 4.16 ± 0.44 km·h-1) was approximately 20% slower than the gross ES (level 5.15 ± 0.18, uphill 5.27 ± 0.20, and downhill 5.37 ± 0.22 km·h-1, P < 0.001). Both net and gross ES were not significantly dependent on the gradient. In contrast, the gross EOTS was slower than the net EOTS at the level (7.49 ± 0.32 vs. 7.63 ± 0.36 km·h-1, P = 0.003) and downhill gradients (7.78 ± 0.33 vs. 8.01 ± 0.41 km·h-1, P < 0.001), but not at the uphill gradient (7.55 ± 0.37 vs. 7.63 ± 0.51 km·h-1, P = 0.080). Note that those percent differences were less than 2.9%. Given these results, a subtraction of the standing oxygen cost should be carefully considered depending on the purpose of each study. PMID:26383249

  13. Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films

    NASA Astrophysics Data System (ADS)

    Yang, Sang Mo; Lee, Shinbuhm; Jian, Jie; Zhang, Wenrui; Lu, Ping; Jia, Quanxi; Wang, Haiyan; Won Noh, Tae; Kalinin, Sergei V.; MacManus-Driscoll, Judith L.

    2015-10-01

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2 films. By using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness.

  14. Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films.

    PubMed

    Yang, Sang Mo; Lee, Shinbuhm; Jian, Jie; Zhang, Wenrui; Lu, Ping; Jia, Quanxi; Wang, Haiyan; Noh, Tae Won; Kalinin, Sergei V; MacManus-Driscoll, Judith L

    2015-01-01

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2 films. By using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness. PMID:26446866

  15. Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films

    DOE PAGESBeta

    Yang, Sangmo; Lee, Shinbuhm; Jian, Jie; Zhang, Wenrui; Lu, Ping; Jia, Quanxi; Wang, Haiyan; Noh, Tae Won; Kalinin, Sergei V.; MacManus-Driscoll, Judith L.

    2015-10-08

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2 films. Bymore » using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness.« less

  16. Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films

    SciTech Connect

    Yang, Sangmo; Lee, Shinbuhm; Jian, Jie; Zhang, Wenrui; Lu, Ping; Jia, Quanxi; Wang, Haiyan; Noh, Tae Won; Kalinin, Sergei V.; MacManus-Driscoll, Judith L.

    2015-10-08

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2 films. By using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness.

  17. Proline Modulates the Trypanosoma cruzi Resistance to Reactive Oxygen Species and Drugs through a Novel D, L-Proline Transporter

    PubMed Central

    Sayé, Melisa; Miranda, Mariana R.; di Girolamo, Fabio; de los Milagros Cámara, María; Pereira, Claudio A.

    2014-01-01

    Trypanosoma cruzi, the etiological agent of Chagas' disease, has a metabolism largely based on the consumption of glucose and proline. This amino acid is essential for host cells infection and intracellular differentiation. In this work we identified a proline transporter (TcAAAP069) by yeasts complementation assays and overexpression in Trypanosoma cruzi epimastigotes. TcAAAP069 is mono-specific for proline but presents an unusual feature; the lack of stereospecificity, because it is competitively inhibited by the D- enantiomer. Parasites overexpressing TcAAAP069 have an increased intracellular proline concentration, 2.6-fold higher than controls, as a consequence of a higher proline transport rate. Furthermore, augmented proline concentration correlates with an improved resistance to trypanocidal drugs and also to reactive oxygen species including hydrogen peroxide and nitric oxide, emulating natural physiological situations. The IC50s for nifurtimox, benznidazole, H2O2 and NO. were 125%, 68%, 44% and 112% higher than controls, respectively. Finally, proline metabolism generates a higher concentration (48%) of ATP in TcAAAP069 parasites. Since proline participates on essential energy pathways, stress and drug resistance responses, these results provide a novel target for the development of new drugs for the treatments for Chagas' disease. PMID:24637744

  18. Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films

    PubMed Central

    Yang, Sang Mo; Lee, Shinbuhm; Jian, Jie; Zhang, Wenrui; Lu, Ping; Jia, Quanxi; Wang, Haiyan; Won Noh, Tae; Kalinin, Sergei V.; MacManus-Driscoll, Judith L.

    2015-01-01

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2 films. By using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness. PMID:26446866

  19. Low temperature transport measurements on atomically smooth metallic and oxygen deficient strontium titanate

    NASA Astrophysics Data System (ADS)

    Barquist, C. S.; Kwak, I. H.; Bauer, J.; Edmonds, T.; Biswas, A.; Lee, Y.

    2014-12-01

    Atomically smooth, TiO2 terminated SrTiO3 (STO) substrates were prepared using a combination of chemical and thermal annealing treatments. The TiO2 terminated surface was obtained by etching with aqua regia solution and thermal annealing at 1000 °C for 30 min. The subsequent vacuum annealing at 830 °C for 10 min generated an atomically smooth and metallic surface of STO. In this paper, we report low temperature transport measurements down to 50 mK on these samples which clearly exhibit a metallic temperature dependence in the resistance. The samples show no sign of superconductivity down to the lowest temperatures.The Rsquare(T) data provide information on the physical origin of metallic behavior in STO, which might also be relevant to the current research interest in oxide interfaces.

  20. Convective and Diffusive O2 Transport Components of Peak Oxygen Uptake Following Long-duration Spaceflight

    NASA Technical Reports Server (NTRS)

    Ade, Carl J.; Moore, A. D.

    2014-01-01

    Spaceflight reduces aerobic capacity and may be linked with maladaptations in the O2 transport pathway. The aim was to 1) evaluate the cardiorespiratory adaptations following 6 months aboard the International Space Station and 2) model the contributions of convective (Q (raised dot) O2) and peripheral diffusive (DO2) components of O2 transport to changes in peak O2 uptake (V (raised dot) O2PEAK). To date, 1 male astronaut (XX yrs) completed an incremental exercise test to measure V (raised dot) O2PEAK prior to and 2 days post-flight. Cardiac output (Q (raised dot) ) was measured at three submaximal work rates via carbon dioxide rebreathing. The Q (raised dot) :V (raised dot) O2 relationship was extrapolated to V (raised dot) O2PEAK to determine Q (raised dot) PEAK. Hemoglobin concentration was measured at rest via a venous blood sample. These measurements were used to model the changes in Q (raised dot) O2 and DO2 using Fick's principle of mass conservation and Law of Diffusion as established by Wagner and colleagues (Annu. Rev. Physiol 58: 21-50, 1996 and J. Appl. Physiol. 73: 1067-1076, 1992). V (raised dot) O2PEAK decreased postflight from 3.72 to 3.45 l min-1, but Q (raised dot) PEAK increased from 24.5 to 27.7 l min-1. The decrease in V (raised dot) O2PEAK post-flight was associated with a 21.2% decrease in DO2, an 18.6% decrease in O2 extraction, but a 3.4% increase in Q (raised dot) O2. These preliminary data suggest that long-duration spaceflight reduces peripheral diffusing capacity and that it largely contributes to the post-flight decrease in aerobic capacity.

  1. Limiting factors to oxygen transport on Mount Everest 30 years after: a critique of Paolo Cerretelli's contribution to the study of altitude physiology.

    PubMed

    Ferretti, Guido

    2003-10-01

    In 1976, Paolo Cerretelli published an article entitled "Limiting factors to oxygen transport on Mount Everest" in the Journal of Applied Physiology. The paper demonstrated the role of cardiovascular oxygen transport in limiting maximal oxygen consumption (VO2max). In agreement with the predominant view of VO2max limitation at that time, however, its results were taken to mean that cardiovascular oxygen transport does not limit VO2max at altitude. So it was argued that the limiting factor could be in the periphery, and muscle blood flow was proposed as a possible candidate. Despite this suggestion, the conclusion generated a series of papers on muscle structural characteristics. These experiments demonstrated a loss of muscle oxidative capacity in chronic hypoxia, and thus provided an unambiguous refutation of the then widespread hypothesis that an increased muscle oxidative capacity is needed at altitude to compensate for the lack of oxygen. This analysis is followed by a short account of Cerretelli's more recent work, with a special attention to the subject of the so-called "lactate paradox". PMID:14530980

  2. Defects, stoichiometry, and electronic transport in SrTiO3-δ epilayers: A high pressure oxygen sputter deposition study

    NASA Astrophysics Data System (ADS)

    Ambwani, P.; Xu, P.; Haugstad, G.; Jeong, J. S.; Deng, R.; Mkhoyan, K. A.; Jalan, B.; Leighton, C.

    2016-08-01

    SrTiO3 is not only of enduring interest due to its unique dielectric, structural, and lattice dynamical properties, but is also the archetypal perovskite oxide semiconductor and a foundational material in oxide heterostructures and electronics. This has naturally focused attention on growth, stoichiometry, and defects in SrTiO3, one exciting recent development being such precisely stoichiometric defect-managed thin films that electron mobilities have finally exceeded bulk crystals. This has been achieved only by molecular beam epitaxy, however (and to a somewhat lesser extent pulsed laser deposition (PLD)), and numerous open questions remain. Here, we present a study of the stoichiometry, defects, and structure in SrTiO3 synthesized by a different method, high pressure oxygen sputtering, relating the results to electronic transport. We find that this form of sputter deposition is also capable of homoepitaxy of precisely stoichiometric SrTiO3, but only provided that substrate and target preparation, temperature, pressure, and deposition rate are carefully controlled. Even under these conditions, oxygen-vacancy-doped heteroepitaxial SrTiO3 films are found to have carrier density, mobility, and conductivity significantly lower than bulk. While surface depletion plays a role, it is argued from particle-induced X-ray emission (PIXE) measurements of trace impurities in commercial sputtering targets that this is also due to deep acceptors such as Fe at 100's of parts-per-million levels. Comparisons of PIXE from SrTiO3 crystals and polycrystalline targets are shown to be of general interest, with clear implications for sputter and PLD deposition of this important material.

  3. Cord blood transplantation in children with haematological malignancies.

    PubMed

    Bertaina, Alice; Bernardo, Maria Ester; Caniglia, Maurizio; Vinti, Luciana; Giorgiani, Giovanna; Locatelli, Franco

    2010-06-01

    Umbilical cord blood transplantation (UCBT) is largely used to treat children affected by haematological malignant disorders. In comparison to bone marrow transplantation (BMT), advantages of UCBT include lower incidence and severity of graft-versus-host disease, easier procurement and prompter availability of cord blood cells, and the possibility of using donors having HLA disparities with the recipient. The large experience accumulated so far has shown that UCBT offers to children a probability of cure at least comparable to that of patients transplanted with bone marrow cells. Since it has been demonstrated that an inverse correlation between the number of nucleated cord blood cells infused per kg recipient body weight and the risk of dying for transplantation-related causes exists, recently developed strategies aimed at increasing the number of cord blood progenitors and at favouring stem cell homing could further optimize the outcome of children with leukemia or other malignancies receiving UCBT. PMID:20837330

  4. William Hewson (1739-74): the father of haematology.

    PubMed

    Doyle, Derek

    2006-05-01

    William Hewson has been called the father of haematology. Initially working alongside the Hunter brothers in London in the mid-18th century, he advanced our knowledge of red and white cells (but mistakenly thought some red cells started as white cells and could not recognise different varieties of white corpuscles), showed that it was fibrinogen and not the cells that led to coagulation, greatly advanced our knowledge of the lymphatic system in humans, fishes and amphibians, explored the functions of the thymus and spleen and, investigated pneumothorax and surgical emphysema. His life, cut short at 35 years, was often intertwined with those of the Hunters, Alexander Monro secundus and Benjamin Franklin. This paper reviews his work, his relationships and his impact on a nascent science. PMID:16643443

  5. Guidelines for genomic array analysis in acquired haematological neoplastic disorders.

    PubMed

    Schoumans, Jacqueline; Suela, Javier; Hastings, Ros; Muehlematter, Dominique; Rack, Katrina; van den Berg, Eva; Berna Beverloo, H; Stevens-Kroef, Marian

    2016-05-01

    Genetic profiling is important for disease evaluation and prediction of prognosis or responsiveness to therapy in neoplasia. Microarray technologies, including array comparative genomic hybridization and single-nucleotide polymorphism-detecting arrays, have in recent years been introduced into the diagnostic setting for specific types of haematological malignancies and solid tumours. It can be used as a complementary test or depending on the neoplasia investigated, also as a standalone test. However, comprehensive and readable presentation of frequently identified complex genomic profiles remains challenging. To assist diagnostic laboratories, standardization and minimum criteria for clinical interpretation and reporting of acquired genomic abnormalities detected through arrays in neoplastic disorders are presented. © 2016 Wiley Periodicals, Inc. PMID:26774012

  6. Haematology of wild penguins (spenisciformes) in the Falkland Islands.

    PubMed

    Hawkey, C M; Horsley, D T; Keymer, I F

    1989-07-01

    Haematological values were determined in 50 Rockhopper (Eudyptes crestatus), 19 Gentoo (Pygoscelis papua) and 12 Magellanic (Spheniscus magellanicus) penguins from various sites on the Falkland Islands. Adult Magellanic penguins had significantly lower haemoglobin (Hb) levels, packed cell volumes (PCV) and red cell counts (RBC) than adults of the other two species. Hb, PCV and RBC values were also lower in juvenile birds than in adults and lower in post-moult than in pre-moult adults. Comparison of findings in wild Rockhopper and Gentoo penguins with values obtained from captive birds showed slight but significant differences in Hb and mean cell haemoglobin concentration, and in the relative numbers of heterophils, lymphocytes, monocytes and eosinophils present. PMID:18679879

  7. Effects of erythropoietin on systemic hematocrit and oxygen transport in the splenectomized horse.

    PubMed

    McKeever, Kenneth H; McNally, Beth A; Hinchcliff, Kenneth W; Lehnhard, Robert A; Poole, David C

    2016-05-01

    To test the hypotheses that erythropoietin (rhuEPO) treatment increases systemic hematocrit, maximal O2 uptake (VO2max, by elevated perfusive and diffusive O2 conductances) and performance five female horses (4-13 years) received 15 IU/kg rhuEPO (erythropoietin) three times per week for three weeks. These horses had been splenectomized over 1 year previously to avoid confounding effects from the mobilization of splenic red blood cell reserves. Each horse performed three maximal exercise tests (one per month) on an inclined (4°) treadmill to the limit of tolerance; two control trials and one following EPO treatment. Measurements of hemoglobin concentration ([Hb] and hematocrit), plasma and blood volume, VO2, cardiac output as well as arterial and mixed venous blood gases were made at rest and during maximal exercise. EPO increased resting [Hb] by 18% from 13.3 ± 0.6 to 15.7 ± 0.8 g/dL (mean ± SD) corresponding to an increased hematocrit from 36 ± 2 to 46 ± 2% concurrent with 23 and 10% reductions in plasma and blood volume, respectively (all P<0.05). EPO elevated VO2max by 20% from 25.7 ± 1.7 to 30.9 ± 3.4 L/min (P<0.05) via a 17% increase in arterial O2 content and 18% greater arteriovenous O2 difference in the face of an unchanged cardiac output. To achieve the greater VO2max after EPO, diffusive O2 conductance increased ∼ 30% (from 580 ± 76 to 752 ± 166 mL O2/mmHg/min, P<0.05) which was substantially greater than the elevation of perfusive O2 conductance. These effects of EPO were associated with an increased exercise performance (total running time: control, 216 ± 72; EPO, 264 ± 48 s, P<0.05). We conclude that EPO substantially increases VO2max and performance in the splenectomized horse via improved perfusive and diffusive O2 transport. PMID:26853328

  8. Effect of Ionization Potential of Hole Transport Layer on Device Characteristics of Organic Light Emitting Diode with Oxygen Plasma Treated Indium Tin Oxide

    NASA Astrophysics Data System (ADS)

    Hashimoto, Yuichi; Hamagaki, Manabu; Sakakibara, Takeshi

    2001-07-01

    We have investigated the contribution of the oxygen ions and electrons, and of the kinetic energy of these species on oxygen plasma treatment of indium tin oxide (ITO) electrode. In the case of the treatment by positive oxygen ions with kinetic energy of 50 eV, the luminance increased markedly with a lowering of the operating voltage in the organic light emitting diode (OLED). The change in the device characteristics was attributed to an effective removal of organic contaminants from the ITO surface, leading to enhanced hole injection from ITO to a hole transport layer (HTL) due to an increase in work function of the ITO@. Moreover, the highest luminance and luminous efficiency were obtained in the OLED having HTL with ionization potential of 5.4 eV@. These results have suggested that OLEDs fabricated using the oxygen plasma treated ITO can give the best device performance by the selection of an optimum HTL.

  9. GASP - THERMODYNAMIC AND TRANSPORT PROPERTIES OF HELIUM, METHANE, NEON, NITROGEN, CARBON MONOXIDE, CARBON DIOXIDE, OXYGEN, AND ARGON

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.

    1994-01-01

    A computer program, GASP, has been written to calculate the thermodynamic and transport properties of argon, carbon dioxide, carbon monoxide, fluorine, methane, neon, nitrogen, and oxygen. GASP accepts any two of pressure, temperature, or density as input. In addition, entropy and enthalpy are possible inputs. Outputs are temperature, density, pressure, entropy, enthalpy, specific heats, expansion coefficient, sonic velocity, viscosity, thermal conductivity, and surface tension. A special technique is provided to estimate the thermal conductivity near the thermodynamic critical point. GASP is a group of FORTRAN subroutines. The user typically would write a main program that invoked GASP to provide only the described outputs. Subroutines are structured so that the user may call only those subroutines needed for his particular calculations. Allowable pressures range from 0.l atmosphere to 100 to l,000 atmospheres, depending on the fluid. Similarly, allowable pressures range from the triple point of each substance to 300 degrees K to 2000 degrees K, depending on the substance. The GASP package was developed to be used with heat transfer and fluid flow applications. It is particularly useful in applications of cryogenic fluids. Some problems associated with the liquefication, storage, and gasification of liquefied natural gas and liquefied petroleum gas can also be studied using GASP. This program is written in FORTRAN IV for batch execution and is available for implementation on IBM 7000 series computers. GASP was developed in 1971.

  10. Effects of oxygen content on the structural and transport properties in epitaxial Nd0.7Sr0.3MnO thin films

    NASA Astrophysics Data System (ADS)

    Meng, Ying; He, Wenlan; Li, Aixia; Li, Guang; Jin, Shaowei

    2012-07-01

    Epitaxial Nd0.7Sr0.3MnO3-x (NSMO) thin films, 120 nm thickness, were grown coherently on the (0 0 1) (LaAlO3)0.3 (Sr2AlTaO6)0.7 (LSAT) substrates by using pulsed-laser deposition (PLD). Effects of oxygen contents controlled by post-annealing in vacuum on the structural and transport properties of the NSMO films were carefully studied by x-ray reciprocal space maps (RSMs) and resistivity measurements. It is clearly shown that both the out-of-plane lattice parameters of the films and the transition temperatures Tp (peak resistance) can simultaneously change as the oxygen contents, the in-plane lattice coherency is maintained consistently with that of the LSAT substrate at the same time. The larger altered transport properties are chiefly ascribed to the increase of Mn3+ ions and the distortion of MnO6 octahedra in films. The oxygen compositions are deduced from the out-of-plane lattice parameters of coherency epitaxy NSMO films. The Kröger-Vink notation was used for explaining the correlation of oxygen vacancy and transport properties.

  11. Low shear red cell oxygen transport effectiveness is adversely affected by transfusion and further worsened by deoxygenation in sickle cell disease patients on chronic transfusion therapy

    PubMed Central

    Detterich, Jon; Alexy, Tamas; Rabai, Miklos; Dongelyan, Ani; Coates, Thomas; Wood, John; Meiselman, Herbert

    2012-01-01

    BACKGROUND Simple chronic transfusion therapy (CTT) is a mainstay for stroke prophylaxis in sickle cell anemia, but its effects on hemodynamics are poorly characterized. Transfusion improves oxygen carrying capacity, reducing demands for high cardiac output. While transfusion decreases factors associated with vaso-occlusion, including percent HbS, reticulocyte count and circulating cell-free hemoglobin, it increases blood viscosity, which reduces microvascular flow. The hematocrit to viscosity ratio (HVR) is an index of red cell oxygen transport effectiveness that varies with shear stress and balances the benefits of improved oxygen capacity to viscosity-mediated impairment of microvascular flow. We hypothesized that transfusion would improve HVR at high shear despite increased blood viscosity, but would decrease HVR at low shear. STUDY DESIGN AND METHODS To test this hypothesis, we examined oxygenated and deoxygenated blood samples from 15 sickle cell patients on CTT immediately pre-transfusion and again 12–120 hours post-transfusion. RESULTS Comparable changes in hemoglobin, hematocrit, reticulocyte count and hemoglobin S with transfusion were observed in all subjects. Viscosity, hematocrit and high-shear HVR increased with transfusion while low shear HVR decreased significantly. CONCLUSION Decreased low-shear HVR suggests impaired oxygen transport to low-flow regions and may explain why some complications of sickle cell anemia are ameliorated by chronic transfusion therapy and others may be made worse. PMID:22882132

  12. Physical complications in anorexia nervosa. Haematological and neuromuscular changes in 12 patients.

    PubMed

    Alloway, R; Shur, E; Obrecht, R; Russell, G F

    1988-07-01

    Of twelve patients consecutively admitted to the Maudsley Hospital Eating Disorders Unit, four had neuromuscular abnormality, eight haematological abnormality, and four no abnormality. All those having neuromuscular signs had concomitant haematological dysfunction. Vomiting, and food restriction with vegetarianism, appeared more likely to lead to complications than either food restriction alone or laxative abuse. The physical status of severely underweight patients admitted for refeeding needs to be carefully monitored. PMID:3224253

  13. Single- and Bayesian Multi-Marker Genome-Wide Association for Haematological Parameters in Pigs

    PubMed Central

    Ponsuksili, Siriluck; Reyer, Henry; Trakooljul, Nares; Murani, Eduard

    2016-01-01

    Haematological traits are important traits that show associations with immune and metabolic status, as well as diseases in humans and animals. Mapping genome regions that affect the blood cell traits can contribute to the identification of genomic features useable as biomarkers for immune, disease and metabolic status. A genome-wide association study (GWAS) was conducted using PorcineSNP60 BeadChips. Single-marker and Bayesian multi-marker approaches were integrated to identify genomic regions and corresponding genes overlapping for both methods. GWAS was performed for haematological traits of 591 German Landrace pig. Heritability estimates for haematological traits were medium to high. In total 252 single SNPs associated with 12 haematological traits were identified (NegLog10 of p-value > 5). The Bayesian multi-marker approach revealed 102 QTL regions across the genome, indicated by 1-Mb windows with contribution to additive genetic variance above 0.5%. The integration of both methods resulted in 24 overlapping QTL regions. This study identified overlapping QTL regions from single- and multi-marker approaches for haematological traits. Identifying candidate genes that affect blood cell traits provides the first step towards the understanding of the molecular basis of haematological phenotypes. PMID:27434032

  14. [The state of acid-alkaline balance and oxygen-transport function of blood in patients with acute carotid ischemic stroke].

    PubMed

    Zhdanova, S G; Aliev, E S; Kamchatnov, P R; Mikhaĭlova, N A

    2012-01-01

    The gas composition, acid-alkaline state of arterial and venous blood and oxygen-transport function in carotid ischemic stroke was studied in 97 patients admitted to a hospital in the first 24h after stroke. Measurements were made at admission and after 5-7 days and 21-23 days. The relative hyperoxia, which reached maximal values to the first day, was found in patients in the acute stage of ischemic stroke. The increase in partial pressure of CO2 (pCO2) and relative acidosis seen to 5-7 days represent the compensatory reaction and lead to the increase in affinity of hemoglobin to oxygen thus improving the tissue oxygenation. We found the inverse correlations between the parameters of oxygen delivery (OD) and oxygen consumption (OC) in the first day and the severity of neurological deficit assessed with the NIHSS in the 21-23 days (r = -0.42; p < 0.01 and r = -0.55; p < 0.01 for OD and OC, respectively), i.e., the decrease in oxygen delivery and consumption corresponded to the greater severity of the stroke course. PMID:23390649

  15. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham

    2006-06-30

    A non-agglomerated and nanocrystalline-sized powder was successfully produced using ethylene glycol nitrate methods. The LSFT powder prepared using this method exhibits well dispersed and nano-sized particles about 100-200 nm. The density of LSFT sintered at 1300 C was about 90% of the theoretical density at which is 100 C less than that of the previous LSFT which was sintered at 1400 C. The sample sintered at 1400 C exhibited the evidence of a liquid phase at the grain boundaries and 2nd phase formation which probably caused low mechanical stability. The electrical conductivity and Seebeck coefficient were measured as a function of temperature. The LSFT-CGO specimens were cut from the as sintered bars and used for the evaluation of Mechanical Properties after polishing. The effect of strain rate on the flexural strength of the LSFT-CGO test specimens was studied. Three strain rates 6, 60 and 600 {micro}m/ min were chosen for this study. It is observed from the results that with increasing cross head speed the membrane takes higher loads to fail. A reduction in the strength of the membrane was observed at 1000 C in N{sub 2}. Two different routes were investigated to synthesis GDC using either formate or carbonate precursors. The precursor and CGO particle morphologies were examined by scanning electron microscopy. The thermal decomposition behaviors of Ce(Gd)(HCOO){sub 3} and Ce(Gd)(CO{sub 3})(OH) were determined by thermogravimetric analysis (TGA) at a rate of 3 C/min in air. The X-ray powder diffraction patterns of the precursor and CGO were collected and nitrogen adsorption isotherms were measured. Conductivity measurements were made by AC impedance spectroscopy on sintered disks in air using platinum electrodes.

  16. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-05-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  17. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-05-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped Ti-substituted perovskites, La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Ti{sub x}O{sub 3}, with 0 {le} x {le} 0.20, were investigated by neutron diffraction, magnetization, electric resistivity, and magnetoresistance (MR) measurements. All samples show a rhombohedral structure (space group R3C) from 10 K to room temperature. At room temperature, the cell parameters a, c and the unit cell volume increase with increasing Ti content. However, at 10 K, the cell parameter a has a maximum value for x = 0.10, and decreases for x > 0.10, while the unit cell volume remains nearly constant for x > 0.10. The average (Mn,Ti)-O bond length increases up to x = 0.15, and the (Mn,Ti)-O-(Mn,Ti) bond angle decreases with increasing Ti content to its minimum value at x = 0.15 at room temperature. Below the Curie temperature TC, the resistance exhibits metallic behavior for the x {le} 0.05 samples. A metal (semiconductor) to insulator transition is observed for the x {ge} 0.10 samples. A peak in resistivity appears below TC for all samples, and shifts to a lower temperature as x increases. The substitution of Mn by Ti decreases the 2p-3d hybridization between O and Mn ions, reduces the bandwidth W, and increases the electron-phonon coupling. Therefore, the TC shifts to a lower temperature and the resistivity increases with increasing Ti content. A field-induced shift of the resistivity maximum occurs at x {le} 0.10 compounds. The maximum MR effect is about 70% for La{sub 0.7}Sr{sub 0.3}Mn{sub 0.8}Ti{sub 0.2}O{sub 3}. The separation of TC and the resistivity maximum temperature T{sub {rho},max} enhances the MR effect in these compounds due to the weak coupling between the magnetic ordering and the resistivity as compared with La{sub 0.7}Sr{sub 0.3}MnO{sub 3}. The bulk densities of the membranes were determined using the Archimedes method. The bulk density was 5.029 and 5.57 g/cc for LSFT and dual phase membranes, respectively. The microstructure of the dual phase membrane was analyzed using SEM. It is evident from the micrograph that the microstructure is composed of dual phases. The dense circular regions are enclosed by the less dense, continuous phase which accommodates most of the pores. The pores are normally aggregated and found clustered along the dense regions where as the dense regions do not have pores. Upon closer observation of the micrograph it is revealed that the dense region has a clear circular cleavage or crack as their boundary. The circular cleavage clearly encompasses a dense region and which consists of no pore or any flaw that is visible. The size distribution of the dense, discontinuous regions is varying from 5 to 20 {micro}m with a D{sub 50} of 15 {micro}m. The grain size distribution was estimated from the micrographs using image analysis and a unimodal distribution of grains was observed with an average grain size of 1.99 {micro}m. The chemical compositions of the membranes were analyzed using EDS analysis and no other impurities were observed. The XRD analysis was carried out for the membranes and the phase purity was confirmed. The fracture toughness of LSFT membranes at room temperature has to be calculated using the Vickers indentation method. An electrochemical cell has been designed and built for measurements of the ionic conductivity by the use of blocking electrodes. Preliminary measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} are reported. Modifications to the apparatus to improve the data quality have been completed. Electron microscopy studies of the origin of the slow kinetics on reduction of ferrites have been initiated. A series of isotope transients under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradient

  18. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendfra Nagabhushana

    2001-07-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  19. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-07-01

    This is the fourth quarterly report on a new study to develop a ceramic membrane/metal joint. The first experiments using the La-Sr-Fe-O ceramic are reported. Some of the analysis performed on the samples obtained are commented upon. A set of experiments to characterize the mechanical strength and thermal fatigue properties of the joints has been designed and begun. Finite element models of joints used to model residual stresses are described.

  20. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2006-05-01

    In this quarter a systematic analysis on the decomposition behavior of the OTM membranes at air and nitrogen were initiated to understand the structural and stoichiometric changes associated with elevated temperatures. Evaluation of the flexural strengths using 4-point bend test was also started for the dual phase membranes. Initial results on the synthesis of dual phase composite materials have been obtained. The measurements have focused on the compatibility of mixed conductors with the pure ionic conductors yttria stabilized zirconia (YSZ) and gadolinium doped ceria (GDC). The initial results obtained for three different mixed conductors suggest that (GDC) is the better choice. A new membrane permeation system has been designed and tested and sintering studies of biphasic systems are in progress.

  1. Dual-Phase Oxygen Transport Membranes for Stable Operation in Environments Containing Carbon Dioxide and Sulfur Dioxide.

    PubMed

    Garcia-Fayos, Julio; Balaguer, María; Serra, José M

    2015-12-21

    Dual-phase membranes are appealing candidates for oxygen transport membranes owing to their unique combination of ambipolar electron-ion transport and endurance. However, O2 separation in industrial environments demands very high stability and effectiveness in the presence of CO2- and SO2-bearing process gases. Here, the composition of dual-phase membranes based on NiFe2O4-Ce(0.8) Tb(0.2)O(2-δ) (NFO-CTO) was optimized and the effective performance of catalytically-activated membranes was assessed in presence of CO2 and SO2. Further insight into the limiting mechanisms in the permeation was gained through electrical conductivity studies, permeation testing in several conditions and impedance spectroscopy analysis. The dual-phase membranes were prepared by one-pot sol-gel method and their permeability increases with increasing fluorite content. An O2 flux of 0.25 (ml min(-1)  cm(-2)) mm at 1000 °C was obtained for a thick self-standing membrane with 40:60 NFO/CTO composition. An in-depth study mimicking typical harsh conditions encountered in oxyfuel flue gases was performed on a 50:50 NFO/CTO membrane. CO2 content as well as SO2 presence in the sweep gas stream were evaluated in terms of O2 permeation. O2 fluxes of 0.13 and 0.09 mL min(-1)  cm(-2) at 850 °C were obtained for a 0.59 mm thick membrane under CO2 and 250 ppm SO2 in CO2 sweep conditions, respectively. Extended periods at work under CO2- and SO2-containing atmospheres revealed good permeation stability over time. Additionally, XRD, backscattered electrons detector (BSD)-SEM, and energy-dispersive X-ray spectroscopy (EDS) analysis of the spent membrane confirmed material stability upon prolonged exposure to SO2. PMID:26586419

  2. Oxygen evolution from single- and multiple-turnover light pulses: temporal kinetics of electron transport through PSII in sunflower leaves.

    PubMed

    Oja, Vello; Eichelmann, Hillar; Laisk, Agu

    2011-12-01

    Oxygen evolution per single-turnover flash (STF) or multiple-turnover pulse (MTP) was measured with a zirconium O(2) analyzer from sunflower leaves at 22 °C. STF were generated by Xe arc lamp, MTP by red LED light of up to 18000 μmol quanta m(-2) s(-1). Ambient O(2) concentration was 10-30 ppm, STF and MTP were superimposed on far-red background light in order to oxidize plastoquinone (PQ) and randomize S-states. Electron (e(-)) flow was calculated as 4 times O(2) evolution. Q (A) → Q (B) electron transport was investigated firing double STF with a delay of 0 to 2 ms between the two. Total O(2) evolution per two flashes equaled to that from a single flash when the delay was zero and doubled when the delay exceeded 2 ms. This trend was fitted with two exponentials with time constants of 0.25 and 0.95 ms, equal amplitudes. Illumination with MTP of increasing length resulted in increasing O(2) evolution per pulse, which was differentiated with an aim to find the time course of O(2) evolution with sub-millisecond resolution. At the highest pulse intensity of 2.9 photons ms(-1) per PSII, 3 e(-) initially accumulated inside PSII and the catalytic rate of PQ reduction was determined from the throughput rate of the fourth and fifth e(-). A light response curve for the reduction of completely oxidized PQ was a rectangular hyperbola with the initial slope of 1.2 PSII quanta per e(-) and V (m) of 0.6 e(-) ms(-1) per PSII. When PQ was gradually reduced during longer MTP, V (m) decreased proportionally with the fraction of oxidized PQ. It is suggested that the linear kinetics with respect to PQ are apparent, caused by strong product inhibition due to about equal binding constants of PQ and PQH(2) to the Q (B) site. The strong product inhibition is an appropriate mechanism for down-regulation of PSII electron transport in accordance with rate of PQH(2) oxidation by cytochrome b(6)f. PMID:22038184

  3. Why Are High-Altitude Natives So Strong at Altitude? Maximal Oxygen Transport to the Muscle Cell in Altitude Natives.

    PubMed

    Lundby, Carsten; Calbet, Jose A L

    2016-01-01

    In hypoxia aerobic exercise performance of high-altitude natives is suggested to be superior to that of lowlanders; i.e., for a given altitude natives are reported to have higher maximal oxygen uptake (VO2max). The likely basis for this is a higher pulmonary diffusion capacity, which in turn ensures higher arterial O2 saturation (SaO2) and therefore also potentially a higher delivery of O2 to the exercising muscles. This review focuses on O2 transport in high-altitude Aymara. We have quantified femoral artery O2 delivery, arterial O2 extraction and calculated leg VO2 in Aymara, and compared their values with that of acclimatizing Danish lowlanders. All subjects were studied at 4100 m. At maximal exercise SaO2 dropped tremendously in the lowlanders, but did not change in the Aymara. Therefore arterial O2 content was also higher in the Aymara. At maximal exercise however, fractional O2 extraction was lower in the Aymara, and the a-vO2 difference was similar in both populations. The lower extraction levels in the Aymara were associated with lower muscle O2 conductance (a measure of muscle diffusion capacity). At any given submaximal exercise intensity, leg VO2 was always of similar magnitude in both groups, but at maximal exercise the lowlanders had higher leg blood flow, and hence also higher maximum leg VO2. With the induction of acute normoxia fractional arterial O2 extraction fell in the highlanders, but remained unchanged in the lowlanders. Hence high-altitude natives seem to be more diffusion limited at the muscle level as compared to lowlanders. In conclusion Aymara preserve very high SaO2 during hypoxic exercise (likely due to a higher lung diffusion capacity), but the effect on VO2max is reduced by a lower ability to extract O2 at the muscle level. PMID:27343089

  4. Assessment of suspended-sediment transport, bedload, and dissolved oxygen during a short-term drawdown of Fall Creek Lake, Oregon, winter 2012-13

    USGS Publications Warehouse

    Schenk, Liam N.; Bragg, Heather M.

    2014-01-01

    The drawdown of Fall Creek Lake resulted in the net transport of approximately 50,300 tons of sediment from the lake during a 6-day drawdown operation, based on computed daily values of suspended-sediment load downstream of Fall Creek Dam and the two main tributaries to Fall Creek Lake. A suspended-sediment budget calculated for 72 days of the study period indicates that as a result of drawdown operations, there was approximately 16,300 tons of sediment deposition within the reaches of Fall Creek and the Middle Fork Willamette River between Fall Creek Dam and the streamgage on the Middle Fork Willamette River at Jasper, Oregon. Bedload samples collected at the station downstream of Fall Creek Dam during the drawdown were primarily composed of medium to fine sands and accounted for an average of 11 percent of the total instantaneous sediment load (also termed sediment discharge) during sample collection. Monitoring of dissolved oxygen at the station downstream of Fall Creek Dam showed an initial decrease in dissolved oxygen concurrent with the sediment release over the span of 5 hours, though the extent of dissolved oxygen depletion is unknown because of extreme and rapid fouling of the probe by the large amount of sediment in transport. Dissolved oxygen returned to background levels downstream of Fall Creek Dam on December 18, 2012, approximately 1 day after the end of the drawdown operation.

  5. Haematological characteristics associated with parasitism in bream, Abramis brama orientalis.

    PubMed

    Hayatbakhsh, Mohammad Reza; Khara, Hossein; Movahed, Rashideh; Sayadborani, Mohammad; Rohi, Javad Daghigh; Ahmadnezhad, Mohadesseh; Rahbar, Mina; Rad, Amir Sajedi

    2014-12-01

    A parasitological investigation was done on 175 specimens. Infections of A. brama orientalis were analyzed according to the age and sex. The fish also were examined for evaluation changes of haematological parameters in relation to parasitic infection. Four parasites were found, including-Caryophyllaeus laticeps and Ligula intestinalis (Cestoda), Diplostomum spathaceum (Platyhelminthes) and Trichodina sp. (Ciliophora). Among identified parasites maximum prevalence and mean intensity were related to Ligula intestinalis and Caryophyllaeus laticeps respectively. The values of prevalence and mean intensity showed significant differences among ages. Our results revealed prevalence, mean intensity and abundance had not significant difference between males and females. Parasite infection provoked reduction (P < 0.05) in haematocrit, mean cell volume and lymphocyte. On the other hand, significant increase (P < 0.05) in white blood cell (WBC), mean cell haemoglobin concentration and neutrophil in blood of infected fish was observed. Significant differences were detected for the WBC, lymphocyte and neutrophil (infected versus uninfected by Trichodina sp., Diplostomum spathaceum and Caryophyllaeus laticeps). In addition to WBC and lymphocytes, significant change was observed for the haemoglobin (Hb) (infected versus uninfected by Ligula intestinalis). PMID:25320488

  6. A cluster of Candida krusei infections in a haematological unit

    PubMed Central

    Hautala, Timo; Ikäheimo, Irma; Husu, Heidi; Säily, Marjaana; Siitonen, Timo; Koistinen, Pirjo; Vuopio-Varkila, Jaana; Koskela, Markku; Kujala, Pekka

    2007-01-01

    Background Candida krusei infections are associated with high mortality. In order to explore ways to prevent these infections, we investigated potential routes for nosocomial spread and possible clonality of C. krusei in a haematological unit which had experienced an unusually high incidence of cases. Methods We searched for C. krusei contamination of the hospital environment and determined the level of colonization in patients and health care workers. We also analyzed the possible association between exposure to prophylactic antifungals or chemotherapeutic agents and occurrence of C. krusei. The C. krusei isolates found were genotyped by pulsed-field electrophoresis method in order to determine possible relatedness of the cases. Results Twelve patients with invasive C. krusei infection and ten patients with potentially significant infection or mucosal colonization were documented within nine months. We were unable to identify any exogenic source of infection or colonization. Genetic analysis of the isolates showed little evidence of clonal transmission of C. krusei strains between the patients. Instead, each patient was colonized or infected by several different closely related genotypes. No association between medications and occurrence of C. krusei was found. Conclusion Little evidence of nosocomial spread of a single C. krusei clone was found. The outbreak may have been controlled by cessation of prophylactic antifungals and by intensifying infection control measures, e.g. hand hygiene and cohorting of the patients, although no clear association with these factors was demonstrated. PMID:17711592

  7. Current status of chimeric antigen receptor therapy for haematological malignancies.

    PubMed

    Maude, Shannon; Barrett, David M

    2016-01-01

    The field of adoptive cell transfer includes chimeric antigen receptor (CAR) engineered T cells, constructs that emerged from basic research into principles of immunology and have transformed into clinically effective therapies for haematological malignancies. T cells engineered to express these artificial receptors hold great promise, but also carry significant risk. While permanent genetic modification of mature T cells appears safe, modulating their in vivo function is difficult, partly because the robust response can trigger other arms of the immune system. Suicide systems and toxicity management with cytokine blockade or signal transduction modulators have emerged as a new frontier in this field, a far cry from early problems getting CAR T cells to work at all. Currently, clinical trials in patients with relapsed or refractory B cell malignancies treated with CD19-specific CAR T cells have induced durable remissions in adults and children. Results from these trials indicate that more work needs to be done to understand biomarkers of efficacy, the role of T cell persistence and how to integrate this care into standard practice. Cell therapy will not be a 'one size fits all' class of medicine, and here we will discuss the development of this therapy and important questions for its future. PMID:26560054

  8. Use of tunnelled catheters in haematological malignancy patients with neutropenia.

    PubMed

    Sariosmanoglu, N; Uğurlu, B; Turgut, N H; Demirkan, F; Ozsan, H; Ergor, G; Gulay, Z; Hazan, E; Oto, O

    2008-01-01

    This prospective study analysed 83 patients (age 45 +/- 17 years) with haematological neoplasms, implanted with 93 tunnelled catheters, who were neutropenic or developed neutropenia during treatment. Catheters were implanted in the right (n = 82) or left (n = 11) jugular vein by the same surgical team using the same technique. They remained in place for 124 +/- 88 days: 29% were removed due to infection; 18% due to treatment termination and 2% due to mechanical problems. Seventeen patients died with catheters in place. At 30, 60, 90, 120 and 200 days mean catheter duration rates were 82%, 75%, 65%, 60% and 35%, respectively, and freedom from catheter removal due to infection was 92%, 88%, 80%, 77% and 67%, respectively. Patient diagnosis and history of previous catheter infection did not increase catheter infection risk, but patients undergoing stem cell transplantation had an increased infection risk. Tunnelled catheters can be used in high-risk patients with neutropenia. Systemic infections can be managed in most patients without catheter removal. PMID:18831907

  9. Curriculum Design of a Flipped Classroom to Enhance Haematology Learning

    NASA Astrophysics Data System (ADS)

    Porcaro, Pauline A.; Jackson, Denise E.; McLaughlin, Patricia M.; O'Malley, Cindy J.

    2016-06-01

    A common trend in higher education is the "flipped" classroom, which facilitates active learning during class. The flipped approach to teaching was instituted in a haematology `major' class and the students' attitudes and preferences for the teaching materials were surveyed. The curriculum design was explicit and involved four major components (1) the preparation of the students; (2) the weekly pre-class work; (3) the in-class active learning strategies and (4) closing the learning loop using formative quizzes. Each of these components is discussed in detail and was informed by sound pedagogical strategies. Several different sources of information and several freely available software tools to engage the students are discussed. Two iterations are reported here, with improved pass rate for the final examination from 47 to 48 % in the traditional class to 56-65 % in the flipped classroom approach. The majority of students (93 and 89 %) came to the class prepared, after viewing the screencasts and engaged fully with the activities within the face-to-face time. The students perceived that solving case studies (93 %) was the most beneficial activity for their learning and this was closely followed by the production of essay plans (71 %). The majority of students recommended that this approach be repeated the following year (69 and 75 %).

  10. Haematological manifestations of human immune deficiency virus infection.

    PubMed

    Vishnu, Prakash; Aboulafia, David M

    2015-12-01

    Early in the human immunodeficiency virus (HIV) epidemic, infected patients presented to medical attention with striking abnormalities in each of the major blood cell lineages. The reasons for these derangements remain complex and multifactorial. HIV infects multipotent haematopoietic progenitor cells and establish latent cellular reservoirs, disturbs the bone marrow microenvironment and also causes immune dysregulation. These events lead to cytokine imbalances and disruption of other factors required for normal haematopoiesis. Activation of the reticulo-endothelial system can also result in increased blood cell destruction. The deleterious effects of medications, including first and second generation anti-retroviral agents, on haematopoiesis were well documented in the early years of HIV care; in the current era of HIV-care, the advent of newer and less toxic anti-retroviral drugs have had a more beneficial impact on haematopoiesis. Due to impaired regulation of the immune system and potential side effects of one or more anti-retroviral agents, there is also an increase in coagulation abnormalities such as thromboembolism, and less frequently, acquired disorders of coagulation including thrombotic thrombocytopenic purpura, immune thrombocytopenic purpura and acquired inhibitors of coagulation. In this article we review the epidemiology and aetiology of select non-oncological haematological disorders commonly seen in people living with HIV-acquired immune deficiency syndrome. PMID:26452169